William E. White

Laser pulses with a power of ${10}^{12}$ W and a duration of ${10}^{\mathrm{\ensuremath{-}}13}$ s were focused onto both gas and solid targets. Strong emission of pulsed radiation at terahertz frequencies was observed from the resulting plasmas. The most intense radiation was detected from solid density targets and was correlated with the emission of MeV x rays and electrons. Results indicate that radiative processes in such plasmas are driven by ponderomotively induced space charge fields in excess of ${10}^{8}$ V/cm. This work constitutes the first direct observation of a laser-induced wake field.

One Protein, Two Probes A central challenge in the use of x-ray diffraction to characterize macromolecular structure is the propensity of the high-energy radiation to damage the sample during data collection. Recently, a powerful accelerator-based, ultrafast x-ray laser source has been used to determine the geometric structures of small protein crystals too fragile for conventional diffraction techniques. Kern et al. (p. 491 , published online 14 February) now pair this method with concurrent x-ray emission spectroscopy to probe electronic structure, as well as geometry, and were able to characterize the metal oxidation states in the oxygen-evolving complex within photosystem II crystals, while simultaneously verifying the surrounding protein structure.

We discuss the use of second-harmonic generation (SHG) as the nonlinearity in the technique of frequency-resolved optical gating (FROG) for measuring the full intensity and phase evolution of an arbitrary ultrashort pulse. FROG that uses a third-order nonlinearity in the polarization-gate geometry has proved extremely successful, and the algorithm required for extraction of the intensity and the phase from the experimental data is quite robust. However, for pulse intensities less than ~1 MW, third-order nonlinearities generate insufficient signal strength, and therefore SHG FROG appears necessary. We discuss the theoretical, algorithmic, and experimental considerations of SHG FROG in detail. SHG FROG has an ambiguity in the direction of time, and its traces are somewhat unintuitive. Also, previously published algorithms are generally ineffective at extracting the intensity and the phase of an arbitrary laser pulse from the SHG FROG trace. We present an improved pulse-retrieval algorithm, based on the method of generalized projections, that is far superior to the previously published algorithms, although it is still not so robust as the polarization-gate algorithm. We discuss experimental sources of error such as pump depletion and group-velocity mismatch. We also present several experimental examples of pulses measured with SHG FROG and show that the derived intensities and phases are in agreement with more conventional diagnostic techniques, and we demonstrate the high-dynamic-range capability of SHG FROG. We conclude that, despite the above drawbacks, SHG FROG should be useful in measuring low-energy pulses.

The Linac Coherent Light Source (LCLS) is an x-ray free-electron laser project presently in a commissioning phase at the SLAC National Accelerator Laboratory. We report here on very low-emittance measurements made at low bunch charge, and a few femtosecond bunch length produced by the LCLS bunch compressors. Start-to-end simulations associated with these beam parameters show the possibilities of generating hundreds of GW at 1.5 \AA{} x-ray wavelength and nearly a single longitudinally coherent spike at 1.5 nm with 2-fs duration.

Although investigations of medieval plague victims have identified Yersinia pestis as the putative etiologic agent of the pandemic, methodological limitations have prevented large-scale genomic investigations to evaluate changes in the pathogen's virulence over time. We screened over 100 skeletal remains from Black Death victims of the East Smithfield mass burial site (1348–1350, London, England). Recent methods of DNA enrichment coupled with high-throughput DNA sequencing subsequently permitted reconstruction of ten full human mitochondrial genomes (16 kb each) and the full pPCP1 (9.6 kb) virulence-associated plasmid at high coverage. Comparisons of molecular damage profiles between endogenous human and Y. pestis DNA confirmed its authenticity as an ancient pathogen, thus representing the longest contiguous genomic sequence for an ancient pathogen to date. Comparison of our reconstructed plasmid against modern Y. pestis shows identity with several isolates matching the Medievalis biovar; however, our chromosomal sequences indicate the victims were infected with a Y. pestis variant that has not been previously reported. Our data reveal that the Black Death in medieval Europe was caused by a variant of Y. pestis that may no longer exist, and genetic data carried on its pPCP1 plasmid were not responsible for the purported epidemiological differences between ancient and modern forms of Y. pestis infections.

Elastic to Plastic When a crystal is mechanically compressed, it first reacts elastically (reversibly), and then enters the plastic regime, in which the structure of the material is irreversibly changed. This process can be studied with molecular dynamics (MD) simulations on very fine temporal and spatial scales, but experimental analysis has lagged behind. Milathianaki et al. (p. 220 ) shocked polycrystalline copper with a laser beam, and then took successive snapshots of the crystal structure at 10-picosecond intervals. The results were compared directly with atomistic simulations and revealed that the yield stress—the point of transition from plastic to elastic response—agreed well with MD predictions.

We report measurements of laser absorption for high-contrast ultrashort pulses on a variety of solid targets over an intensity range of ${10}^{13}$ to ${10}^{18}$ W/ ${\mathrm{cm}}^{2}$. These data give an experimental determination of the target energy content and an indirect measure of dense plasma electrical conductivity. Our calculations accurately reproduce the behavior of aluminum targets, while the other materials show signs of additional absorption mechanisms. At high intensity all target materials reach a ``universal plasma mirror'' state and reflect about 90% of the incident light.

The Linac Coherent Light Source is a SASE x-ray free-electron laser (FEL) project presently under construction at SLAC [J. Arthur et al., SLAC-R-593, 2002.]. The injector section, from drive laser and rf photocathode gun through first bunch compressor chicane, was installed in the fall of 2006. The initial system commissioning with an electron beam was completed in August of 2007, with the goal of a 1.2-micron emittance in a 1-nC bunch demonstrated. The second phase of commissioning, including second bunch compressor and full linac, is planned for 2008, with FEL commissioning in 2009. We report experimental results and experience gained in the first phase of commissioning, including the photocathode drive laser, rf gun, photocathode, S-band and X-band rf systems, first bunch compressor, and the various beam diagnostics.

The first time-resolved x-ray/optical pump-probe experiments at the SLAC Linac Coherent Light Source (LCLS) used a combination of feedback methods and post-analysis binning techniques to synchronize an ultrafast optical laser to the linac-based x-ray laser. Transient molecular nitrogen alignment revival features were resolved in time-dependent x-ray-induced fragmentation spectra. These alignment features were used to find the temporal overlap of the pump and probe pulses. The strong-field dissociation of x-ray generated quasi-bound molecular dications was used to establish the residual timing jitter. This analysis shows that the relative arrival time of the Ti:Sapphire laser and the x-ray pulses had a distribution with a standard deviation of approximately 120 fs. The largest contribution to the jitter noise spectrum was the locking of the laser oscillator to the reference RF of the accelerator, which suggests that simple technical improvements could reduce the jitter to better than 50 fs.

An electrospun liquid microjet has been developed that delivers protein microcrystal suspensions at flow rates of 0.14–3.1 µl min −1 to perform serial femtosecond crystallography (SFX) studies with X-ray lasers. Thermolysin microcrystals flowed at 0.17 µl min −1 and diffracted to beyond 4 Å resolution, producing 14 000 indexable diffraction patterns, or four per second, from 140 µg of protein. Nanoflow electrospinning extends SFX to biological samples that necessitate minimal sample consumption.

The Linac Coherent Light Source free electron laser is a source of high brightness x rays, 2 Â 10 11 photons in a $5 fs pulse, that can be focused to produce double core vacancies through rapid sequential ionization.This enables double core vacancy Auger electron spectroscopy, an entirely new way to study femtosecond chemical dynamics with Auger electrons that probe the local valence structure of molecules near a specific atomic core.Using 1.1 keV photons for sequential x-ray ionization of impulsively aligned molecular nitrogen, we observed a rich single-site double core vacancy Auger electron spectrum near 413 eV, in good agreement with ab initio calculations, and we measured the corresponding Auger electron angle dependence in the molecular frame.

This study reports the results of a collaborative study undertaken by two independent research groups to (a) confirm recent PCR-based detection of Yersinia pestis DNA in human teeth from medieval plague victims in France, and (b) to extend these observations over five different European burial sites believed to contain plague victims dating from the late 13th to 17th centuries. Several different sets of primers were used, including those previously documented to yield positive results on ancient DNA extracts. No Y. pestis DNA could be amplified from DNA extracted from 108 teeth belonging to 61 individuals, despite the amplification of numerous other bacterial DNA sequences. Several methods of extracting dentine prior to the DNA extraction were also compared. PCR for bacterial 16S rDNA indicated the presence of multiple bacterial species in 23 out of 27 teeth DNA extracts where dentine was extracted using previously described methods. In comparison, positive results were obtained from only five out of 44 teeth DNA extracts for which a novel contamination-minimizing embedding technique was used. Therefore, high levels of environmental bacterial DNA are present in DNA extracts where previously described methods of tooth manipulation are used. To conclude, the absence of Y. pestis -specific DNA in an exhaustive search using specimens from multiple putative European plague burial sites does not allow us to confirm the identification of Y. pestis as the aetiological agent of the Black Death and subsequent plagues. In addition, the utility of the published tooth-based ancient DNA technique used to diagnose fatal bacteraemias in historical epidemics still awaits independent corroboration.

Most of the dioxygen on earth is generated by the oxidation of water by photosystem II (PS II) using light from the sun. This light-driven, four-photon reaction is catalyzed by the Mn(4)CaO(5) cluster located at the lumenal side of PS II. Various X-ray studies have been carried out at cryogenic temperatures to understand the intermediate steps involved in the water oxidation mechanism. However, the necessity for collecting data at room temperature, especially for studying the transient steps during the O-O bond formation, requires the development of new methodologies. In this paper we report room temperature X-ray diffraction data of PS II microcrystals obtained using ultrashort (< 50 fs) 9 keV X-ray pulses from a hard X-ray free electron laser, namely the Linac Coherent Light Source. The results presented here demonstrate that the "probe before destroy" approach using an X-ray free electron laser works even for the highly-sensitive Mn(4)CaO(5) cluster in PS II at room temperature. We show that these data are comparable to those obtained in synchrotron radiation studies as seen by the similarities in the overall structure of the helices, the protein subunits and the location of the various cofactors. This work is, therefore, an important step toward future studies for resolving the structure of the Mn(4)CaO(5) cluster without any damage at room temperature, and of the reaction intermediates of PS II during O-O bond formation.

Molecules can efficiently and selectively convert light energy into other degrees of freedom. Disentangling the underlying ultrafast motion of electrons and nuclei of the photoexcited molecule presents a challenge to current spectroscopic approaches. Here we explore the photoexcited dynamics of molecules by an interaction with an ultrafast X-ray pulse creating a highly localized core hole that decays via Auger emission. We discover that the Auger spectrum as a function of photoexcitation--X-ray-probe delay contains valuable information about the nuclear and electronic degrees of freedom from an element-specific point of view. For the nucleobase thymine, the oxygen Auger spectrum shifts towards high kinetic energies, resulting from a particular C-O bond stretch in the ππ* photoexcited state. A subsequent shift of the Auger spectrum towards lower kinetic energies displays the electronic relaxation of the initial photoexcited state within 200 fs. Ab-initio simulations reinforce our interpretation and indicate an electronic decay to the nπ* state.

X-ray free-electron laser (XFEL) sources enable the use of crystallography to solve three-dimensional macromolecular structures under native conditions and without radiation damage. Results to date, however, have been limited by the challenge of deriving accurate Bragg intensities from a heterogeneous population of microcrystals, while at the same time modeling the X-ray spectrum and detector geometry. Here we present a computational approach designed to extract meaningful high-resolution signals from fewer diffraction measurements.

Abstract Experimental results and analyses are reported on the corrosion of carbon steel in CO2-saturated environments that typically represent producing well waters encountered in natural gas rese...

The very bright electron beam required for an x-ray free-electron laser (FEL), such as the linac coherent light source (LCLS), is susceptible to a microbunching instability in the magnetic bunch compressors, prior to the FEL undulator. The uncorrelated electron energy spread in the LCLS can be increased by an order of magnitude to provide strong Landau damping against the instability without degrading the FEL performance. To this end, a ``laser-heater'' system has been installed in the LCLS injector, which modulates the energy of a 135-MeV electron bunch with an IR-laser beam in a short undulator, enclosed within a four-dipole chicane. In this paper, we report detailed measurements of laser-heater-induced energy spread, including the unexpected self-heating phenomenon when the laser energy is very low. We discuss the suppression of the microbunching instability with the laser heater and its impact on the x-ray FEL performance. We also present the analysis of these experimental results and develop a three-dimensional longitudinal space charge model to explain the self-heating effect.

A photosensitive azide derivative of ethidium bromide, 3(8)-amino-8(3)-azido-5-ethyl-6-phenyl phenanthridinium chloride, was prepared which binds covalently to DNA via a light-generated nitrene intermediate. When exposed to light in aqueous solvent the azide loses free nitrogen to yield a reactive nitrene, which reacts with water to form the hydroxylamine derivative. When the drug is photolyzed while tightly bound to DNA, rather than free in solution, a covalent complex is generated in situ due to the attack of the nitrene to form a covalent bond with the nucleic acid. A selectivity for cytoplasmic DNA reported previously for ethidium bromide was also shown for the azido analog by enhanced production of petite mutants in Saccharomyces following the photolysis of the azide in vivo. Isolated mitochondrial DNA following binding of the ethidium analog in vivo also appeared to retain a greater number of drug molecules per nucleotide than nuclear DNA. In vitro binding experiments did not suggest the same extent of preferential binding. This technique of photoaffinity labeling provides a means of studying the precise model of binding nucleic acid active drugs in relation to their biological effects.

The LCLS beam provides revolutionary capabilities for studying the transient behavior of matter in extreme conditions. The particular strength of the Matter in Extreme Conditions instrument is that it combines the unique LCLS beam with high-power optical laser beams, and a suite of dedicated diagnostics tailored for this field of science. In this paper an overview of the beamline, the capabilities of the instrumentation, and selected highlights of experiments and commissioning results are presented.

The matter in extreme conditions end station at the Linac Coherent Light Source (LCLS) is a new tool enabling accurate pump–probe measurements for studying the physical properties of matter in the high-energy density (HED) physics regime. This instrument combines the world's brightest x-ray source, the LCLS x-ray beam, with high-power lasers consisting of two nanosecond Nd:glass laser beams and one short-pulse Ti:sapphire laser. These lasers produce short-lived states of matter with high pressures, high temperatures or high densities with properties that are important for applications in nuclear fusion research, laboratory astrophysics and the development of intense radiation sources. In the first experiments, we have performed highly accurate x-ray diffraction and x-ray Thomson scattering measurements on shock-compressed matter resolving the transition from compressed solid matter to a co-existence regime and into the warm dense matter state. These complex charged-particle systems are dominated by strong correlations and quantum effects. They exist in planetary interiors and laboratory experiments, e.g., during high-power laser interactions with solids or the compression phase of inertial confinement fusion implosions. Applying record peak brightness x-rays resolves the ionic interactions at atomic (Ångstrom) scale lengths and measure the static structure factor, which is a key quantity for determining equation of state data and important transport coefficients. Simultaneously, spectrally resolved measurements of plasmon features provide dynamic structure factor information that yield temperature and density with unprecedented precision at micron-scale resolution in dynamic compression experiments. These studies have demonstrated our ability to measure fundamental thermodynamic properties that determine the state of matter in the HED physics regime.

The ultrabright femtosecond X-ray pulses provided by X-ray free-electron lasers open capabilities for studying the structure and dynamics of a wide variety of systems beyond what is possible with synchrotron sources. Recently, this "probe-before-destroy" approach has been demonstrated for atomic structure determination by serial X-ray diffraction of microcrystals. There has been the question whether a similar approach can be extended to probe the local electronic structure by X-ray spectroscopy. To address this, we have carried out femtosecond X-ray emission spectroscopy (XES) at the Linac Coherent Light Source using redox-active Mn complexes. XES probes the charge and spin states as well as the ligand environment, critical for understanding the functional role of redox-active metal sites. Kβ(1,3) XES spectra of Mn(II) and Mn(2)(III,IV) complexes at room temperature were collected using a wavelength dispersive spectrometer and femtosecond X-ray pulses with an individual dose of up to >100 MGy. The spectra were found in agreement with undamaged spectra collected at low dose using synchrotron radiation. Our results demonstrate that the intact electronic structure of redox active transition metal compounds in different oxidation states can be characterized with this shot-by-shot method. This opens the door for studying the chemical dynamics of metal catalytic sites by following reactions under functional conditions. The technique can be combined with X-ray diffraction to simultaneously obtain the geometric structure of the overall protein and the local chemistry of active metal sites and is expected to prove valuable for understanding the mechanism of important metalloproteins, such as photosystem II.

We measured the relative arrival time between an optical pulse and a soft x-ray pulse from a free-electron laser. This femtosecond cross-correlation measurement was achieved by observing the change in optical reflectivity induced through the absorption of a fraction of the x-ray pulse. The main x-ray pulse energy remained available for an independent pump-probe experiment where the sample may be opaque to soft x-rays. The method was employed to correct the two-pulse delay data from a canonical pump-probe experiment and demonstrate 130 ± 20 fs (FWHM) temporal resolution. We further analyze possible timing jitter sources and point to future improvements.

Abstract The work describes a cellular structure configuration with a rectangular perforation topology exhibiting auxetic (negative Poisson's ratio) in‐plane behaviour. The rectangular voids used in this structure produce a rigid rotating squares effect. Changes in the sizing parameters of aspect ratio, intercell spacing, and number of unit cells are made through non‐dimensional modelling. The effects on the key properties of in‐plane Poisson's ratio, Young's modulus and shear modulus are investigated. Through numerical modelling and experimental testing the auxetic behaviour is confirmed, with increased negative Poisson's ratio values in comparison to rhomboidal patterns of perforations available in open literature.

We report experimental results of x-ray amplification of spontaneous emission in a Ni-like transient collisional excitation scheme. The Ni-like plasma formation, ionization, and collisional excitation requires irradiation of a slab target by two laser pulses: a formation beam with 5 J energy of 800 ps duration and a pump beam of 5 J energy in 1.1 ps. A gain of $35{\mathrm{cm}}^{\ensuremath{-}1}$ and a $\mathrm{gL}$ product of 12.5 are measured on the $4d\ensuremath{\rightarrow}4p$ $J\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0\ensuremath{\rightarrow}1$ transition for Ni-like Pd at 147 \AA{} with an 8 mm line focus. The high efficiency of this scheme at ``table-top'' laser energies is a direct consequence of the nonstationary population inversion produced by the high intensity picosecond pulse.

Ultrashort-duration, high-energy laser pulses have been generated using a titanium-doped-sapphire oscillator and amplifier system. The pulses have an energy of 0.45 J with a duration of 95 fs and an energy of 0.23 J with a duration of 60 fs.

The advent of few femtosecond x-ray light sources brings promise of x-ray/optical pump-probe experiments that can measure chemical and structural changes in the 10-100 fs time regime. Widely distributed timing systems used at x-ray Free-Electron Laser facilities are typically limited to above 50 fs fwhm jitter in active x-ray/optical synchronization. The approach of single-shot timing measurements is used to sort results in the event processing stage. This has seen wide use to accommodate the insufficient precision of active stabilization schemes. In this article, we review the current technique for "measure-and-sort" at the Linac Coherent Light Source at the SLAC National Accelerator Laboratory. The relative arrival time between an x-ray pulse and an optical pulse is measured near the experimental interaction region as a spectrally encoded cross-correlation signal. The cross-correlation provides a time-stamp for filter-and-sort algorithms used for real-time sorting. Sub-10 fs rms resolution is common in this technique, placing timing precision at the same scale as the duration of the shortest achievable x-ray pulses.

The Linac Coherent Light Source (LCLS) at the SLAC National Accelerator Laboratory was the first hard X-ray free-electron laser (FEL) to operate as a user facility. After five years of operation, LCLS is now a mature FEL user facility. Our personal views about opportunities and challenges inherent to these unique light sources are discussed.

The Journal of PhysiologyVolume 80, Issue 2 p. 174-178 ArticleFree Access The growth and regression of follicles in the œstrous rabbit Margaret Hill, Margaret HillSearch for more papers by this authorWilliam E. White, William E. WhiteSearch for more papers by this author Margaret Hill, Margaret HillSearch for more papers by this authorWilliam E. White, William E. WhiteSearch for more papers by this author First published: 05 December 1933 https://doi.org/10.1113/jphysiol.1933.sp003080Citations: 21AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume80, Issue2December 5, 1933Pages 174-178 RelatedInformation

In a previous paper (White, 1932) the survival of spermatozoa in the male rat after ligation of the vasa efferentia was reported, motility being the criterion of survival. An attempt has now been made to determine the duration of fertility in animals similarly treated and to correlate motility with fertility. Data on these subjects are given in the present paper, together with certain observation on the histological changes occuring in the reproductive system after vasa-efferentia ligation. Material and Methods .—Fifty-three males and a larger number of females were used in this work. The procedure of vasa-efferentia ligation was the same as used in previous studies and was briefly as follows: under full anæthesia with ether, a median incision was made in the scrotum, exposing the tunica vaginalis of the testis. The testis and epididymis were then withdrawn, through an opening in this sheath, and the vasa efferentia (ductuli efferentes) dissected out of the fast lying between the testis and the head of the eppidiymis. These ducts were carefully ligated in two places and severed between the ligatures. The testis and epididymis were then replaced in the sheath, which was sutured with silk, and the skin wound closed with suture clips. Aseptic technique was used throughout.

The Journal of PhysiologyVolume 80, Issue 2 p. 193-205 ArticleFree Access Relation of the pituitary gland to the action of insulin and adrenaline A. B. Corkill, A. B. CorkillSearch for more papers by this authorH. P. Marks, H. P. MarksSearch for more papers by this authorW. E. White, W. E. WhiteSearch for more papers by this author A. B. Corkill, A. B. CorkillSearch for more papers by this authorH. P. Marks, H. P. MarksSearch for more papers by this authorW. E. White, W. E. WhiteSearch for more papers by this author First published: 05 December 1933 https://doi.org/10.1113/jphysiol.1933.sp003082Citations: 17AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume80, Issue2December 5, 1933Pages 193-205 RelatedInformation

We have developed a system that provides monotonic tuning of the higher-order frequency-dependent phase of ultrashort laser pulses. This technique utilizes geometric aberrations that arise from adjustments to the relative alignment of the elements of an air-spaced doublet lens. In a system such as a diffraction-grating stretcher, the spectral components of the optical pulses are spatially dispersed, and lens aberrations introduce frequency-dependent phase shifts. A numerical model of a general chirped-pulsed amplification system has been developed and verified by comparison with experimental and analytical results. Numerical results indicating that higher-order phase terms can be compensated by a properly adjusted air-spaced doublet design within the pulse stretcher are presented.

Harmonic seeding of free electron lasers has attracted significant attention as a method for producing transform-limited pulses in the soft x-ray region. Harmonic multiplication schemes extend seeding to shorter wavelengths, but also amplify the spectral phase errors of the initial seed laser, and may degrade the pulse quality and impede production of transform-limited pulses. In this paper we consider the effect of seed laser phase errors in high gain harmonic generation and echo-enabled harmonic generation. We use simulations to confirm analytical results for the case of linearly chirped seed lasers, and extend the results for arbitrary seed laser envelope and phase.

The linac coherent light source (LCLS) is a self-amplified spontaneous emission (SASE) free-electron laser (FEL) operating at fundamental photon energies from 0.5 to 10 keV. Characterization of the higher harmonics present in the FEL beam is important to users, for whom harder x rays can either extend the useful operating wavelength range or increase experimental backgrounds. We present measurements of the power in both the second and third harmonics, and compare the results to expectations from simulations. We also present studies of the transport of harmonics to the users, and the harmonic power as a function of electron beam quality.

Ultrafast optical lasers play an essential role in exploiting the unique capabilities of recently commissioned X-ray free-electron laser facilities such as the Linac Coherent Light Source (LCLS). Pump-probe experimental techniques reveal ultrafast dynamics in atomic and molecular processes and reveal new insights in chemistry, biology, material science and high-energy-density physics. This manuscript describes the laser systems and experimental methods that enable cutting-edge optical laser/X-ray pump-probe experiments to be performed at LCLS.

In recent years the effect of surgically removing the pituitary gland has received considerable attention. two classes of vertebrates, Amphibia and Mammalia, have largely been used in these studies. Practically all the experimental work on ablation in mammals has been done on two species, namely, dogs (Cushing et al ., 1910; Aschner, 1912; Houssay, 1931; and many others), and more recently rats (Smith, 1930; and others). Following the epoch-making discovered of Smith and Engle (1926) and Aschheim and Zondek (1927), that implanted pituitary gland will hasten sexual maturity in the rat, a number of workers have been attempting to isolate the hormones from the anterior lobe. It has become increasingly apparent that adequate test animals are necessary for the physiological assay of the various hormone fractions and it is now equally apparent that only with animals whose pituitaries have been removed may purified products be assayed with any certainty. The peculiarities of the rabbits reproductive cycle and also its possible utility for hormone assay, make it unusually interesting for studies on the effect of hypophysectomy, but the inaccessibility of the gland has somewhat retarded work on this species. In conjunction with Dr. L. L. Smith, however, method for ablating the pituitary was recently elaborated (Smith and White, 1931) which left the animals essentially healthy so that they survived for considerable periods. It therefore seemed interesting to determine the extent of the changes caused by hypophysectomy in the rabbit and to attempt substitution therapy with purified hormones. The data on untreated hypophysectomized animals will be presented in the present paper.

The Journal of PhysiologyVolume 81, Issue 3 p. 335-360 ArticleFree Access The assay of the ovulation-producing substance R. Towner Hill, R. Towner HillSearch for more papers by this authorA. S. Parkes, A. S. ParkesSearch for more papers by this authorW. E. White, W. E. WhiteSearch for more papers by this author R. Towner Hill, R. Towner HillSearch for more papers by this authorA. S. Parkes, A. S. ParkesSearch for more papers by this authorW. E. White, W. E. WhiteSearch for more papers by this author First published: 09 June 1934 https://doi.org/10.1113/jphysiol.1934.sp003139Citations: 15AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume81, Issue3June 9, 1934Pages 335-360 RelatedInformation

The Anatomical RecordVolume 54, Issue 2 p. 253-273 Article The effect of hypophysectomy on the survival of spermatozoa in the male rat† William E. White, William E. White Department of Anatomy, College of Physicians and Surgeons, Columbia UniversitySearch for more papers by this author William E. White, William E. White Department of Anatomy, College of Physicians and Surgeons, Columbia UniversitySearch for more papers by this author First published: October 1932 https://doi.org/10.1002/ar.1090540212Citations: 14 † Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy, in the Faculty of Pure Science, Columbia University. ‡ Columbia University Fellow. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume54, Issue2October 1932Pages 253-273 RelatedInformation

We introduce a technique for simultaneously measuring the time-dependent intensity and phase of two independent and arbitrary ultrashort laser pulses from a single measured spectrogram. This two-pulse method is mathematically equivalent to the problem of blind deconvolution, and we use an algorithm analogous to those used for deblurring two-dimensional images to recover the two pulses. We demonstrate the method by simultaneously retrieving the intensity and the phase of two different pulses from a Ti:sapphire laser, one of which is chirped by propagation through glass.

We measure the spectral phase of femtosecond optical pulses using a time–frequency analog of Young’s double-slit interference. A pair of narrow slits in an opaque sheet selects two spectral frequencies from the femtosecond pulse spectrum in a zero-dispersion pulse stretcher. Measurement of the temporal phase of a family of beat frequencies obtained over a range of slit spacings yields the desired spectral phase directly. We demonstrate this technique by accurately measuring the quadratic phase added to 80-fs optical pulses by a 6.5-cm block of BK-7 glass.

Many observers have noted that the morphological changes that occur in chronic kidney disease (CKD) patients resemble those seen in the geriatric population, with strikingly similar morbidity and mortality profiles and rates of frailty in the two groups, and shared characteristics at a pathophysiological level especially in respect to the changes seen in their vascular and immune systems. However, whilst much has been documented about the shared physical characteristics of aging and uremia, the molecular and cellular similarities between the two have received less attention. In order to bridge this perceived gap we have reviewed published research concerning the common molecular processes seen in aging subjects and CKD patients, with specific attention to altered proteostasis, mitochondrial dysfunction, post-translational protein modification, and senescence and telomere attrition. We have also sought to illustrate how the cell death and survival pathways apoptosis, necroptosis and autophagy are closely interrelated, and how an understanding of these overlapping pathways is helpful in order to appreciate the shared molecular basis behind the pathophysiology of aging and uremia. This analysis revealed many common molecular characteristics and showed similar patterns of cellular dysfunction. We conclude that the accelerated aging seen in patients with CKD is underpinned at the molecular level, and that a greater understanding of these molecular processes might eventually lead to new much needed therapeutic strategies of benefit to patients with renal disease.

Whole blood volume can be measured quite accurately by the use of radiochromium. The amount of radiation is very low; the radiochromium stays fixed in red blood cells for many hours and does not leave the circulation as may happen when plasma tags are employed. Hypervolemia was found in the majority of patients with right ventricular failure but not in those with left ventricular failure or mitral stenosis alone.

We have developed a combined Ti:Al2O3/Cr:LiSrAlF6 laser system capable of producing terawatt pulses with a duration of 120 fs at a 1-Hz repetition rate. Chirped-pulse amplification in Ti:sapphire produces compressed 45-mJ pulses. Further amplification in flash-lamp-pumped Cr:LiSrAlF6 produces 150-mJ compressed pulses with no significant effect on beam quality or pulse shape.

Frameshift mutations have been produced in specific repair-negative Salmonella tester strains by photoaffinity labeling technique using ethidium azide. Reversions requiring a +1 addition or a -2 deletion were specially sensitive. Mutagenesis was reduced by the simultaneous addition of non-mutagenic ethidium bromide, and was prevented by photolysis of the azide prior to culture addition. Identical tester strains active in DNA excision repaire were not mutagenized by the azide. These results are consistent with the interpretation that photolysis of the bound ethidium analog converts the drug from its noncovalent mode of binding (presumably intercalation) to a covalent complex with consequent production of frameshift mutations. Such photoaffinity labeling by drugs which bind to DNA not only confirms the importance of covalent drug attachment for frameshift mutagenesis, but also provides powerful techniques for studying the molecular deatils of a variety of genetic mechanisms.

Ethidium bromide (EB) is known as a highly efficient mutagen of mitochondrial DNA in yeast. The key step to mutagenesis is thought to be a covalent EB attachment to mitochondrial DNA. A light sensitive ethidium azide has been used to produce covalent attachment of ethidium to mitochondrial DNA under conditions where EB mutagenesis does not occur, i.e. at high glucose concentrations, and in the petite negative yeast K. fragilis. A bypass attachment of ethidium through photolysis of the azide was effective in inducing mutagenesis.

The Linac Coherent Light Source is now in operation as an X-ray free-electron laser (FEL) user facility. It produces coherent pulses of 550–10,000 eV X-rays of duration adjustable from <10 fsto500 fs. Typical peak power is in excess of 20 GW. The facility will soon be joined by several X-ray FELs under construction around the world. This article will provide an abridged history of free-electron lasers, a description of some basic physics regarding free-electron laser light amplification, and an overview of the rapidly growing list of examples in which lasers will be used in the control and operation of X-ray FELs.

Rationale: The balance between vascular prostacyclin, which is antithrombotic, and platelet thromboxane A 2 , which is prothrombotic, is fundamental to cardiovascular health. Prostacyclin and thromboxane A 2 are formed after the concerted actions of cPLA 2 α (cytosolic phospholipase A 2 ) and COX (cyclooxygenase). Urinary 2,3-dinor-6-keto-PGF 1α (PGI-M) and 11-dehydro-TXB 2 (TX-M) have been taken as biomarkers of prostacyclin and thromboxane A 2 formation within the circulation and used to explain COX biology and patient phenotypes, despite concerns that urinary PGI-M and TX-M originate in the kidney. Objective: We report data from a remarkable patient carrying an extremely rare genetic mutation in cPLA 2 α, causing almost complete loss of prostacyclin and thromboxane A 2 , who was transplanted with a normal kidney resulting in an experimental scenario of whole-body cPLA 2 α knockout, kidney-specific knockin. By studying this patient, we can determine definitively the contribution of the kidney to the productions of PGI-M and TX-M and test their validity as markers of prostacyclin and thromboxane A 2 in the circulation. Methods and Results: Metabolites were measured using liquid chromatography-tandem mass spectrometry. Endothelial cells were grown from blood progenitors. Before kidney transplantation, the patient’s endothelial cells and platelets released negligible levels of prostacyclin (measured as 6-keto-prostaglandin F 1α ) and thromboxane A 2 (measured as TXB 2 ), respectively. Likewise, the urinary levels of PGI-M and TX-M were very low. After transplantation and the establishment of normal renal function, the levels of PGI-M and TX-M in the patient’s urine rose to within normal ranges, whereas endothelial production of prostacyclin and platelet production of thromboxane A 2 remained negligible. Conclusions: These data show that PGI-M and TX-M can be derived exclusively from the kidney without contribution from prostacyclin made by endothelial cells or thromboxane A 2 by platelets in the general circulation. Previous work relying on urinary metabolites of prostacyclin and thromboxane A 2 as markers of whole-body endothelial and platelet function now requires reevaluation.

1. The concentration of phosphate in the external medium of a suspension of unfertilized Strongylocentrotus eggs remains constant, or increases, while in a suspension of fertilized eggs, the concentration of phosphate in the external medium decreases.2. Fertilized Strongylocentrotus eggs absorb P32 and phosphate from sea water at identical rates, revealing that the exchange of phosphate between the cell interior and the external medium is inappreciable.3. The rate at which phosphate is removed from sea water by fertilized Strongylocentrotus eggs is relatively independent of the external concentration as long as this exceeds 15 to 20 micrograms P per liter.4. When unfertilized and fertilized sea urchin eggs are continuously exposed to sea water containing P32 and more than 20 micrograms P per liter, 95.9 to 96.4 per cent of the P32 which enters the eggs is found in the trichloroacetic acid-soluble fraction, with 3.6 to 4.1 per cent of the P32 being recovered in the acid-insoluble fraction. The distribution of P32 between these two fractions is not significantly different in the unfertilized, as compared to the fertilized eggs. Although a slightly lower proportion of P32 was found in the acid-insoluble residue of unfertilized eggs, outward leaching of P32 during the washing of the unfertilized eggs may well account for the difference noted.5. If fertilized Lytechinus pictus eggs containing P32 are suspended in a non-radioactive medium shortly after insemination, the proportion of P32 in the acid-insoluble fraction increases from 3.6 per cent at the two-celled stage to 7.0 per cent at the blastula stage.6. The concentration of inorganic P in the trichloroacetic acid-soluble extracts of the eggs decreases prominently following insemination. A corresponding increase occurs in the quantity of P liberated after 10 minutes' hydrolysis of the extracts in 1 N HCl at 100° C.7. The major portion of the P32 which enters the eggs is found in the easily hydrolyzable P fraction of the trichloroacetic acid-soluble extracts. After fertilization, the proportion of P32 in the easily hydrolyzable P fraction increases.

N-Acetylglycyl adenylate anhydride has been shown to be readily converted in high yield to N-acetylglycyl imidazolide in the presence of excess imidazole at pH 7. The aminoacyl group can then be transferred from the imidazolide to become esters of mono- or polynucleotides. These observations suggest that histidine may be in the active site of the aminoacyl-tRNA synthetases, catalyzing the transfer of aminoacyl groups from the adenylate to tRNA.

Characterizing muscle requires measuring such properties as force–length, force–activation, and force–velocity curves. These characterizations require large numbers of data points because both what type of function (e.g., linear, exponential, hyperbolic) best represents each property, and the values of the parameters in the relevant equations, need to be determined. Only a few properties are therefore generally measured in experiments on any one muscle, and complete characterizations are obtained by averaging data across a large number of muscles. Such averaging approaches can work well for muscles that are similar across individuals. However, considerable evidence indicates that large inter-individual variation exists, at least for some muscles. This variation poses difficulties for across-animal averaging approaches. Methods to fully describe all muscle’s characteristics in experiments on individual muscles would therefore be useful. Prior work in stick insect extensor muscle has identified what functions describe each of this muscle’s properties and shown that these equations apply across animals. Characterizing these muscles on an individual-by-individual basis therefore requires determining only the values of the parameters in these equations, not equation form. We present here techniques that allow determining all these parameter values in experiments on single muscles. This technique will allow us to compare parameter variation across individuals and to model muscles individually. Similar experiments can likely be performed on single muscles in other systems. This approach may thus provide a widely applicable method for characterizing and modeling muscles from single experiments.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Surface Chemistry of Hydrates. IIV. R. DamerellV. R. DamerellMore by V. R. Damerell, F. HovorkaF. HovorkaMore by F. Hovorka, and W. E. WhiteW. E. WhiteMore by W. E. WhiteCite this: J. Phys. Chem. 1932, 36, 4, 1255–1267Publication Date (Print):April 1, 1932Publication History Published online1 May 2002Published inissue 1 April 1932https://doi.org/10.1021/j150334a016Request reuse permissions Article Views37Altmetric-Citations11LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (543 KB) Get e-Alerts

We have developed an ultrashort-pulse laser system in which the final Ti:sapphire amplifier stage is pumped by the frequency-doubled output of a Nd:glass laser. The laser produces pulses with an energy in excess of 1 J on target and an estimated peak focused irradiance of 5 x 10(19) W/cm(2).

The lactoperoxidase-thiocyanate-hydrogen peroxide system was found to have both bacteriostatic and bactericidal activities against strains of Salmonella typhimurium. The bactericidal activity was clearly dependent on the permeability of the bacterial cell envelope. The deep rough mutant TA1535, with the most permeable cell envelope, was killed both at neutral and acid pH, whereas very little or no killing was observed with the intact cells of the parent strain hisG46. The delta gal mutant, TA1530, representing an intermediate in cell envelope permeability, was inhibited to a much lesser extent than TA1535. Bacteria in log phase of growth were more sensitive to the bactericidal effects than were those in stationary phase. Growth phase had little influence on the bacteriostatic effects. The hisG46 strain produced significant quantities of acid in the presence of glucose. This acid production was inhibited by the lactoperoxidase-thiocyanate-hydrogen peroxide system, and, in contrast to results obtained with several strains of streptococci, this inhibition was not reversed by addition of a reducing agent (2-mercaptoethanol).

Emerging technologies are critically evaluated for their feasibility in future light sources. We consider both new technologies for electron beam generation and acceleration suitable for X-ray free-electron lasers (FELs), as well as alternative photon generation technologies including the relatively mature inverse Compton scattering and laser high-harmonic generation. Laser-driven plasma wakefield acceleration is the most advanced of the novel acceleration technologies, and may be suitable to generate electron beams for X-ray FELs in a decade. We provide research recommendations to achieve the needed parameters for driving future light sources, including necessary advances in laser technology.

Here we present the first angle-resolved, non-resonant (normal) Auger spectra for impulsively aligned nitrogen molecules. We have measured the angular pattern of Auger electron emission following K-shell photoionization by 1.1 keV photons from the Linac Coherent Light Source (LCLS). Using strong-field-induced molecular alignment to make molecular frame measurements is equally effective for both repulsive and quasi-bound final states. The capability to resolve Auger emission angular distributions in the molecular frame of reference provides a new tool for spectral assignments in congested Auger electron spectra that takes advantage of the symmetries of the final diction states. Based on our experimental results and theoretical predictions, we propose the assignment of the spectral features in the Auger electron spectrum.

Overview of the laser systems being built for ELI-Beamlines is presented. The facility will make available high-brightness multi-TW ultrashort laser pulses at kHz repetition rate, PW 10 Hz repetition rate pulses, and kilojoule nanosecond pulses for generation of 10 PW peak power. The lasers will extensively employ the emerging technology of diode-pumped solid-state lasers (DPSSL) to pump OPCPA and Ti:sapphire broadband amplifiers. These systems will provide the user community with cutting-edge laser resources for programmatic research in generation and applications of high-intensity X-ray sources, in particle acceleration, and in dense-plasma and high-field physics.

ArticleOVARIAN RESPONSES TO PROLAN AND ANTERIOR PITUITARY EXTRACT IN HYPOPHYSECTOMIZED RABBITS WITH PARTICULAR REFERENCE TO OVULATIONWilliam E. White, and Samuel L. LeonardWilliam E. WhiteFrom the Department of Anatomy, College of Physicians and Surgeons, Columbia University, and Samuel L. LeonardFrom the Department of Anatomy, College of Physicians and Surgeons, Columbia UniversityPublished Online:31 Mar 1933https://doi.org/10.1152/ajplegacy.1933.104.1.44MoreSectionsPDF (923 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation More from this issue > Volume 104Issue 1March 1933Pages 44-50 Copyright & PermissionsCopyright © 1933 by American Physiological Societyhttps://doi.org/10.1152/ajplegacy.1933.104.1.44History Received 24 November 1932 Published online 31 March 1933 Published in print 31 March 1933 Metrics

1. Fresh-water medusæ were observed in Stallworth Lake, an artificial body of water near Tuscaloosa, Alabama. They were first seen by the writer on September 14, 1928. They disappeared on October ninth of the same year and have not been observed since.2. The hydroid stage was not found.3. A description of the lake where the medusæ were found is given.4. A historical survey of the fresh-water medusæ is made.5. The medusæ agree very closely with Craspedacusta ryderi as described by Payne (1924). There are certain differences which may be developmental or due to dissimilar environmental conditions. The medusæ are assigned to the species C. ryderi.6. The tentacles are grouped into four, instead of the three previously used groups.7. Sections of the gonads demonstrated that all the medusæ examined were males.8. Observations on the spermatogenesis of C. ryderi are included.9. Since all gonads obtained were from adult medusæ, no information concerning the origin of the germ cells can be given.10. The primary spermatocytes are only very slightly larger than the spermatogonia.11. There is a meiotic stage in which the chromatin is stained only very poorly with iron hæmatoxylin.12. There seem to be twelve chromosomes at each pole of the late anaphases of the primary spermatocytes.13. Some portions of the sperm are stained more intensely by Flemming's triple method and others by iron hæmatoxylin. Thus the two methods give different appearances to the sperm.14. Tails are not visible on sperm in fixed and stained preparations.

The technique of self-induced plasma shuttering can be used to suppress prepulse energy from an ultrashort pulse. If a femtosecond pulse is incident upon a transparent target, the leading edge passes through while the peak reflects owing to ionization breakdown at the surface. We describe a fluid jet, enclosed in a vacuum chamber, that allows this technique to be used at high repetition rates. The jet has excellent stability and a fast (~500 μs) recovery time. At normal incidence, we demonstrate a reflection efficiency of 70% with a prepulse-to-main-pulse energy suppression ratio of &gt;10, while at Brewster incidence we measure a reflection efficiency of 38% with a suppression ratio of nearly 400.

Corrosion processes are often complex. Mechanisms, even in simple systems, are not always well understood. Corrosion and corrosion-assisted fracture processes in metal components are usually influenced by localized variations associated with the corrosive environments and/or the microstructures of the metallic components in contact with them. Variations in temperature, pressure, velocity, electrolyte concentrations, and stress (loading), as well as the microstructural variables of grain size, grain morphology, inclusions, second phases, dislocation densities, and others can affect corrosion and fracture mechanisms (and their extent) significantly. In this article, the influences of welding on corrosion and corrosion-related phenomena are discussed. It is shown that the application of heat and/or pressure during welding causes microstructural variations across weld zones and heat-affected zones. These variations, in turn, influence the thermodynamics and kinetics of specific corrosion processes leading to accelerated corrosion and/or fracture of the weldment. Light and electron metallographic techniques, along with accelerated electrochemical test methods, were used to measure and monitor the progression of corrosion and fracture damage as influenced by the supporting weld microstructures. The illustrations used were taken from a variety of field and laboratory corrosion studies. The observed corrosion and/or fracture-related damage reported are discussed an explained in terms of fundamental corrosion theory.

Abstract Accelerated electrochemical techniques were used to study the corrosion of carbon steel in laboratory-simulated aqueous environments representing typical produced waters from natural gas production wells. Specifically, the separate and conjoint effects of the various ionic species in the electrolyte, and the influences of dissolved methane and propane on corrosion of the steel were investigated. Tests were performed at temperatures and pressures up to 95 C and 700 kPa, respectively. Some kinetic parameters were evaluated from both anodic and cathodic polarization measurements. The results showed that the reduction of H2O and HCO3− ions is important in explaining the cathodic polarization characteristics. The partial reactions occurring in the system were defined and explained, in part, from theoretical reconstruction of the experimental polarization curves.

Ab initio calculations were performed on 18 fluorinated and unfluorinated alcohols at the B3LYP and HF levels with the 6-311G∗∗ basis set. Molar volumes of the alcohols were computed at each level and averaged to produce a scale of relative size. From this, various isosteric replacements of potential use in drug design were suggested: ethyl by FCH2CH2 or HCF2CH2, propyl by CF3CH2, isopropyl by CF3(CH3)CH or (FCH2)2CH, isobutyl or t-butyl by (CF3)2CH, and 3-methyl-2-butyl by CF3(CH3)2C. Calculation of the charge on oxygen and the Wiberg index of the CO bond allowed an electronegativity scale to be constructed for the fluoroalkyl groups. Electronegativity decreased in the order: (CF3)3C>(CF3)2CH>C2F5CH2>CF3CH2>CH3(CF3)2C>HCF2CH2>CF3(CH3)CH>(FCH2)2CH>FCH2CH2>CF3(CH3)2C. This ranking agreed with literature acid dissociation data for the alcohols studied.

Both ethidium bromide and propidium iodide stain growing yeast. As visualized in the fluorescence microscope, ethidium stains the nucleus and cytoplasm in wild type yeast and in those grown in 10% dextrose, with brightly fluorescent cytoplasmic granules being present in both. Under the latter conditions, the mitochondria are repressed but not absent. In rho 0 cells, in which the mitochondrial DNA is absent, ethidium appears to bind to the cell wall or membrane preferentially with no cytoplasmic granules being visible. In all cell types, propidium appears to bind the cell wall or membrane with no cytoplasmic granules being visible in any cell. The staining patterns thus suggest greater differences in the binding of these two types to mitochondrial DNA in situ than is suggested by their in vitro behavior. These differences in binding could explain their different mutagenic capacities..

1. The ratio of red cell space for inorganic iodine to that of plasma was found to be about 0.5, in both in vitroc and in vivo studies. 2. The initial red cell-plasma ratio was the same in hyperthyroid, euthyroid, and hypothyroid patients immediately after the oral administration of a test dose of I131. 3. The ratio dropped as the inorganic iodine test dose was incorporated into larger molecules by the thyroid and returned to the blood stream. 4. The drop in red cell-plasma ratio was due to the relative impermeability of the red cell to large iodine-containing molecules. 5. The rate of drop of the red cell-plasma ratio is an expression of thyroid activity.

Through the production of prostacyclin, cyclooxygenase (COX)-2 protects the cardiorenal system. Asymmetric dimethylarginine (ADMA), is a biomarker of cardiovascular and renal disease. Here we determined the relationship between COX-2/prostacyclin, ADMA, and renal function in mouse and human models.We used plasma from COX-2 or prostacyclin synthase knockout mice and from a unique individual lacking COX-derived prostaglandins (PGs) because of a loss of function mutation in cytosolic phospholipase A2 (cPLA2), before and after receiving a cPLA2-replete transplanted donor kidney. ADMA, arginine, and citrulline were measured using ultra-high performance liquid-chromatography tandem mass spectrometry. ADMA and arginine were also measured by enzyme-linked immunosorbent assay (ELISA). Renal function was assessed by measuring cystatin C by ELISA. ADMA and prostacyclin release from organotypic kidney slices were also measured by ELISA.Loss of COX-2 or prostacyclin synthase in mice increased plasma levels of ADMA, citrulline, arginine, and cystatin C. ADMA, citrulline, and arginine positively correlated with cystatin C. Plasma ADMA, citrulline, and cystatin C, but not arginine, were elevated in samples from the patient lacking COX/prostacyclin capacity compared to levels in healthy volunteers. Renal function, ADMA, and citrulline were returned toward normal range when the patient received a genetically normal kidney, capable of COX/prostacyclin activity; and cystatin C positively correlated with ADMA and citrulline. Levels of ADMA and prostacyclin in conditioned media of kidney slices were not altered in tissue from COX-2 knockout mice compared to wildtype controls.In human and mouse models, where renal function is compromised because of loss of COX-2/PGI2 signaling, ADMA levels are increased.

Multiple techniques (CO2 and N2 adsorptions, NMR spin relaxation of adsorbed water, He pycnometry and Hg porosimetry) have been combined in a comprehensive study to determine changes in surface area (CO2 and nitrogen), density (solid, particle and bulk), and pore structure (pore size and volume distributions of micro-, meso- and macro-pores) in high-temperature char formation from rank representative U.S. coals of the ANL and PETC Banks (i.e. Beulah Zap, Dietz, Utah Blind Canyon, Pittsburgh No.8 and Pocahontas No.3). Chars were formed at high heating rates in a flat-frame burner (maximum temperature of 1473 K), a process representative of char formation in pulverized coal combustion. Most of the surface area of the coals was found in micropores with radii less than 1.5 nm, while 95% or more of the pore volume in the coals (85% of that in chars) was contained in mesopores less than 20 nm). During the high-temperature formation of char in a flame: (I) CO2 surface areas (involving mainly micropores, rpore < 1.5 nm) increase two- to three-fold, while N2 surface areas (involving mesopores. 1.5 nm < rpore < 20 nm) increase 20–200-fold; (2) solid densities increase about 25% due to graphitization, while particle densities decrease by about a factor of two due to large increases in particle porosity; (3) pore volumes increase 5–10-fold; and (4) total porosities increase three- to four-fold, most of this increase occurring in the macropore range. The larger surface areas and porosities of chars relative to coals may be explained by (i) the removal by pyrolysis of strongly adsorbed molecules or volatile hydrocarbons from micropores and small mesopores that would otherwise hinder access of CO2 and N2 molecules; (ii) the creation of new pores during the restructuring process involved in charification; and (iii) opening up by gasification with oxygen of new pores previously blocked to gas adsorption. The preparation conditions (e.g. atmosphere, heating rate and temperature) greatly affect the physical properties including the surface area, porosity and density of the resulting chars. The degree of carbon burnout is an important correlating factor affecting these properties.

The ability of 18 gram-negative bacterial isolates to detoxify diisopropyl fluorophosphate, a structural analog of the agents soman and sarin, was investigated. Detoxification by both frozen cell sonicates and acetone powders was assayed by two methods, i.e., the hydrolytic release of fluoride, measured by a fluoride-specific ion electrode, and the disappearance of acetylcholinesterase inhibition in vitro. Frozen cell sonicates for all strains exhibited some activity (F- ion release). In general, acetone powder preparations produced higher activity than frozen cell sonicates did, and the highest activities were exhibited by strains with known parathion hydrolase activity. Two ranges in activity were observed, low level, ranging from 0.1 to 7.0 mumol/min per g of protein, and high level, detected only in parathion hydrolase-producing strains, from 47 to greater than 300 mumol/min per g of protein. Results indicate that parathion hydrolase was nonspecific in phosphoesterase activity. Also, it was an effective detoxicant at low concentrations and near-neutral pH.

The hypothiocyanite ion (OSCN - ) is a normal component of human saliva. It is a highly reactive oxidizing agent, and at concentrations above the values normally found in human saliva, it inhibits the growth and metabolism of oral bacteria. This finding has led to the suggestion that antibacterial properties of human saliva might be enhanced in vivo by appropriate supplements which elevate OSCN - concentrations. Since DNA is sensitive to oxidizing agents (hydrogen peroxide attacks nucleosides), high concentrations of OSCN - in human saliva might damage DNA and produce deleterious effects on the oral mucosa. In the present study, the effect of high OSCN - concentrations on several mutagen-sensitive Salmonella typhimurium strains was determined. These strains are used to detect base-pair substitutions and frameshift mutations. We also studied the effects of OSCN - on a Saccharomyces cerevisiae (yeast) strain commonly employed as a test cell for evaluating the potential of a compound to produce gene conversion, mitotic crossing-over, or reverse mutation. By recording the UV spectra of mixtures of calf thymus DNA and OSCN - , we explored the possible in vitro reactions of this oxidizing agent with eucaryotic genetic material. Our results show that, at concentrations above 10 μM, OSCN - is toxic for the tested Salmonella typhimurium strains. The mutant strains with defects in cell wall lipopolysaccharides are killed more readily by OSCN - than is the strain lacking these defects. However, OSCN - was not mutagenic for any of the tested strains. Saccharomyces cerevisiae was not affected by OSCN - even at concentrations above 800 μM. Calf thymus DNA was not oxidized by OSCN - . We conclude that the elevated concentrations of OSCN - required to produce antibacterial effects in the human mouth pose no threat to the genetic material of host tissues.

This work reports the transfer of the N-acetylglycine from the adenylate anhydride to the 2′OH groups along the backbone of homopolyribonucleotides. This transfer involves an N-acetylglycylimidazole intermediate; no transfer was observed in the absence of imidazole, and the rate of transfer was different for the various polynucleotides: poly U > poly A > poly C = poly G = 0. These results suggest that catalysis is necessary for transfer of aminoacyl from adenylates to polyribonucleotides and the data are consistent with a model involving a histidine residue in the active site of aminoacyl-tRNA synthetases. They are also consistent with a model for primordial protein formation involving polymerization of amino acids which are attached at the 2′OH groups along the polyribonucleotide backbone.

Measuring neuron capacitance is important for morphological description, conductance characterization, and neuron modeling. One method to estimate capacitance is to inject current pulses into a neuron and fit the resulting changes in membrane potential with multiple exponentials; if the neuron is purely passive, the amplitude and time constant of the slowest exponential give neuron capacitance (Major G, Evans JD, Jack JJ. Biophys J 65: 423-449, 1993). Golowasch et al. (Golowasch J, Thomas G, Taylor AL, Patel A, Pineda A, Khalil C, Nadim F. J Neurophysiol 102: 2161-2175, 2009) have shown that this is the best method for measuring the capacitance of nonisopotential (i.e., most) neurons. However, prior work has not tested for, or examined how much error would be introduced by, slow voltage-dependent phenomena possibly present at the membrane potentials typically used in such work. We investigated this issue in lobster (Panulirus interruptus) stomatogastric neurons by performing current clamp-based capacitance measurements at multiple membrane potentials. A slow, voltage-dependent phenomenon consistent with residual voltage-dependent conductances was present at all tested membrane potentials (-95 to -35 mV). This phenomenon was the slowest component of the neuron's voltage response, and failure to recognize and exclude it would lead to capacitance overestimates of several hundredfold. Most methods of estimating capacitance depend on the absence of voltage-dependent phenomena. Our demonstration that such phenomena make nonnegligible contributions to neuron responses even at well-hyperpolarized membrane potentials highlights the critical importance of checking for such phenomena in all work measuring neuron capacitance. We show here how to identify such phenomena and minimize their contaminating influence.

Free electron laser (FEL) based x-ray sources show great promise for use in ultrafast molecular studies due to the short pulse durations and site/element sensitivity in this spectral range. However, the self amplified spontaneous emission (SASE) process mostly used in FELs is intrinsically noisy resulting in highly fluctuating beam parameters. Additionally timing synchronization of optical and FEL sources adds delay jitter in pump-probe experiments. We show how we mitigate the effects of source noise for the case of ultrafast molecular spectroscopy of the nucleobase thymine. Using binning and resorting techniques allows us to increase time and spectral resolution. In addition, choosing observables independent of noisy beam parameters enhances the signal fidelity.

The intramuscular injection of butazolidinR in a daily dose of 1.0 g for 2-3 days reduces I131 uptake by the thyroid gland.

ArticleTHE EFFECT ON OVULATION AND PREGNANCY OF BLOCKING THE PITUITARY CIRCULATION IN THE RABBITWilliam E. WhiteWilliam E. WhiteFrom the Department of Anatomy, College of Physicians and Surgeons, Columbia UniversityPublished Online:31 Oct 1932https://doi.org/10.1152/ajplegacy.1932.102.2.505MoreSectionsPDF (888 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation More from this issue > Volume 102Issue 2October 1932Pages 505-511 Copyright & PermissionsCopyright © 1932 by American Physiological Societyhttps://doi.org/10.1152/ajplegacy.1932.102.2.505History Received 8 July 1932 Published online 31 October 1932 Published in print 31 October 1932 Metrics

We demonstrate continuous tuning of the cubic and quartic phases of the pulse stretcher in a chirped-pulse amplification laser system. We obtain near-bandwidth-limited recompression of 100-fs pulses by minimizing the total phase through fourth order.

2-Azidoisopthalic acid and 5-azidoisopthalic acid were prepared from the corresponding amines through diazonium salt intermediates. Kinetic studies indicate that they are competitive inhibitors of glutamate dehydrogenase. Photolysis of the enzyme-inhibitor complex with light > 300 nm generates a nitrene which reacts irreversibly with the enzyme and exhibits fluorescence emission at 430 nm when excited by 350 nm radiation.

The pyloric network of decapod crustaceans has been intensively studied electrophysiologically in the infraorders Astacidea, Brachyura, and Palinura. The morphology of some or all pyloric neurons has been well described in Astacidea and Brachyura, but less so in Palinura. Given the large evolutionary distance between these three groups, and the large amount of electrophysiology that has been performed in palinuroid species, it is important to fill this gap. We describe here the gross morphology of all six pyloric neuron types in a palinuroid, &lt;i&gt;P. interruptus&lt;/i&gt;. All pyloric neurons had complicated, extended dendritic trees that filled the majority of the neuropil, with most small diameter processes present in a shell near the surface of the ganglion. Certain neuron types showed modest preferences for somata location in the ganglion, but these differences were too weak to use as identifying characteristics. Quantitative measurements of secondary branch number, maximum branch order, total process length, and neuron somata diameter were also, in general, insufficient to distinguish among the neurons, although AB and LP neuron somata diameters differed from those of the other types. One neuron type (VD) had a distinctive neurite branching pattern consisting of a small initial branch followed shortly by a bifurcation of the main neurite. The processes arising from these two branches occupied largely non-overlapping neuropil. Electrophysiological recordings showed that each major branch had its own spike initiation zone and that, although the zones fired correlated spikes, they generated spikes independently. VD neurons in the other infraorders have similar morphologies, suggesting that having two arbors is important for the function of this neuron. These data are similar to those previously obtained in Brachyura and Astacidea. It thus appears that, despite their long evolutionary separation, neuron morphology in these three infraorders has not greatly diverged.

Rose bengal tagged with radioiodine (I-131) injected in the vein of a normal subject is rapidly cleared from the blood by the liver and conveyed by the biliary ducts to the intestine. By counting the radioactivity over the heart, liver, and intestine, the liver function (rate of clearing the blood of activity and rate of liver uptake) and patency of the biliary ducts (appearance of activity in the intestines) can be assessed. Patients with hepatitis clear the blood of dye slowly and exhibit a slow liver uptake. Intestinal activity appears somewhat slower than normal but in normal amount. In patients with biliary atresia, the blood is cleared of activity somewhat more slowly than normal. Liver activity, though rising slowly, continues to increase for a much longer period of time than in the normal subject. No activity reaches the intestine. Sixty-five nose bengal studies were carried out in 50 pediatric patients. The test is of most value in evaluating the jaundiced neonate. More experience with it will be necessary to evaluate fully the usefulness of this test.

<h3>Background and Design:</h3> The precise ablation of skin was studied using an ultrashort-pulsed, high-intensity titanium-sapphire (Ti:Al₂O₃) laser capable of peak intensities of tens of terawatts (TW; 1 TW = 10¹²watts [W]) per square centimeter. Rat skin was exposed in vitro to femtosecond-pulsed Ti:Al₂O₃laser radiation at 800 nm, while varying the number of pulses and the intensity up to 46 TW/cm². Ablation was evaluated by monitoring the amount of tissue removed per pulse as a function of energy, and by light microscopic examination of damage to adjacent, nonirradiated tissue. <h3>Observations:</h3> Ablation depth per pulse was 0.1 μm at threshold intensity, and it was increased with both the energy per pulse and the number of pulses. Minimal damage to adjacent healthy tissue was observed, varying 0 to 30 μm. <h3>Conclusion:</h3> The results suggest that ablation of skin with femtosecond-pulsed, terawatt Ti:Al₂O₃laser may have potential for precision cutaneous surgery, and in vivo studies are indicated. (<i>Arch Dermatol.</i>1993;129:989-993)

Abstract Experimental results and analyses on the corrosion of carbon steel in simulated aqueous sour gas environments are reported. Tests were performed at temperatures and pressures up to 95 C (2...

Several 2-azidofluorenes have been synthesized for use as photoaffinity labels inside bacteria. In the dark they were not mutagenic for any Salmonella typhimurium tested. When photolyzed inside the bacteria, all were mutagenic for strain TA1538 to varying degrees, and were considerably less mutagenic in the corresponding repair positive TA1978. None were mutagenic for strain TA1535 or TA1537, although most compounds were toxic for those strains when photolyzed.

The Journal of PhysiologyVolume 79, Issue 2 p. 180-184 ArticleFree Access Ovulation after blood dilution and cross-circulation M. K. McPhail, M. K. McPhailSearch for more papers by this authorA. S. Parkes, A. S. ParkesSearch for more papers by this authorW. E. White, W. E. WhiteSearch for more papers by this author M. K. McPhail, M. K. McPhailSearch for more papers by this authorA. S. Parkes, A. S. ParkesSearch for more papers by this authorW. E. White, W. E. WhiteSearch for more papers by this author First published: 04 September 1933 https://doi.org/10.1113/jphysiol.1933.sp003038Citations: 3AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume79, Issue2September 4, 1933Pages 180-184 RelatedInformation

The Journal of PhysiologyVolume 79, Issue 2 p. 226-229 ArticleFree to Read The excretion of prolan after intravenous injection into the rabbit A. S. Parkes, A. S. ParkesSearch for more papers by this authorW. E. White, W. E. WhiteSearch for more papers by this author A. S. Parkes, A. S. ParkesSearch for more papers by this authorW. E. White, W. E. WhiteSearch for more papers by this author First published: 04 September 1933 https://doi.org/10.1113/jphysiol.1933.sp003044Citations: 5AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat Citing Literature Volume79, Issue2September 4, 1933Pages 226-229 RelatedInformation

We have studied theoretically and experimentally the x-ray production above 1 keV from femtosecond laser plasmas generated on periodically modulated surface targets. Laser energy coupling to plasma surface waves has been modeled using a numerical differential method. Almost total absorption of incident laser radiation is predicted for optimized interaction conditions. Silicon gratings have been irradiated by a 120 fs Ti: sapphire laser at irradiances in excess of 10<SUP>16</SUP>W/cm<SUP>2</SUP>. X-ray intensities above 1.5 keV (K-shell lines) have been measured as a function of the incidence angle. Results show a distinct x-ray emission maximum for the first order diffraction angle and are in good qualitative agreement with our theoretical predictions.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNotes- Hammett Sigma Constants for m-and p-Benzoyl GroupsWilliam White, Robert Schlitt, and Donald GwynnCite this: J. Org. Chem. 1961, 26, 9, 3613–3615Publication Date (Print):September 1, 1961Publication History Published online7 March 2003Published inissue 1 September 1961https://doi.org/10.1021/jo01067a669RIGHTS & PERMISSIONSArticle Views151Altmetric-Citations9LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (376 KB) Get e-Alerts Get e-Alerts

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCommunications. The Electronic Nature of the Transition State of the Claisen Rearrangement.William White, Carl Slater, and Wilmer FifeCite this: J. Org. Chem. 1961, 26, 2, 627–628Publication Date (Print):February 1, 1961Publication History Published online20 February 2003Published inissue 1 February 1961https://doi.org/10.1021/jo01061a626RIGHTS & PERMISSIONSArticle Views43Altmetric-Citations7LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (185 KB) Get e-Alerts Get e-Alerts

Collision-induced dissociation of metal-cationized N-CBZ-Gly-Pro-Gly-Pro-Ala was studied by Fourier transform mass spectrometry. Lithium-, sodium-, potassium- and rubidium-cationized peptide species were generated by matrix-assisted laser desorption/ionization (MALDI) using 2,5-dihydroxybenzoic acid as matrix, together with appropriate metal salts. The experimental mass spectrometric results were interpreted with the aid of Monte Carlo conformational searches using the Amber(*) force field, together with ab initio molecular orbital calculations with Gaussian-94 for the singly lithium- and potassium-cationized peptides. It is concluded that metal coordination plays a key role in guiding the gas-phase fragmentation of the cationized peptide. In contrast to lithium and sodium, potassium and rubidium apparently do not coordinate to the C-terminal carbonyl. When the peptide is cationized with the two smaller alkali metals, losses corresponding to alanine and CBZ are observed, while the coordination of potassium and rubidium results in only CBZ loss upon dissociation.

This study examines the equity consequence of school finance policy changes in Kentucky. It incorporates traditional school finance concerns regarding equity targets, objects, principles, and statistics. It utilizes adjustments for district economies of scale and interdistrict price differences. Findings indicate that Kentucky experienced marked improvements in equity as a result of school finance reform, including a narrower dispersion of pupil revenue and greater fiscal neutrality. Equity improvements resulted from policy changes that effectively addressed disequalizing attributes of the pre-reform state aid formula. Manipulating this formula further could produce additional marginal gains in system equity but at substantial cost.

A sub-line with increased metastatic ability was previously isolated from an established human colonic carcinoma cell line [Kimball &amp; Brattain (1980) Cancer Res. 40, 1574-1579]. The separation and characterization of the isoenzymes of N-acetyl-beta-D-hexosaminidase from each cell line are reported. The parental cell line contained A and B isoenzymes. The sub-line lacked the A-isoenzyme activity and contained an atypical B isoenzyme that was thermolabile, susceptible to alkylation and of lower molecular weight.

Australian Veterinary JournalVolume 49, Issue 12 p. 587-588 INTESTINAL ATRESIA IN CALVES C. Lenghaus B.V.Sc., C. Lenghaus B.V.Sc. Regional Veterinary Laboratory, Department of Agriculture, Hamilton, Victoria, 3300.Search for more papers by this authorW. E. White M.V.Sc., Ph.D., W. E. White M.V.Sc., Ph.D. Regional Veterinary Laboratory, Department of Agriculture, Hamilton, Victoria, 3300.Search for more papers by this author C. Lenghaus B.V.Sc., C. Lenghaus B.V.Sc. Regional Veterinary Laboratory, Department of Agriculture, Hamilton, Victoria, 3300.Search for more papers by this authorW. E. White M.V.Sc., Ph.D., W. E. White M.V.Sc., Ph.D. Regional Veterinary Laboratory, Department of Agriculture, Hamilton, Victoria, 3300.Search for more papers by this author First published: December 1973 https://doi.org/10.1111/j.1751-0813.1973.tb06740.xCitations: 10AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. References Bremer, J. L. (1953). Cited by Wright and Symmers (1966)— “Systematic Pathology”. 1st edn., Longmans, London . Christl, H. Jr. (1970)—-Dt. tierarztl. Wschr 77: 205. Henricson, B. (1963)—Acta vet. Scand. 4: 263. Jubb, K. V. F. and Kennedy, P. C. (1963)— “Pathology of Domestic Animals”. 1st edn., Academic Press, New York and London . Kernkamp, H. C. H. and Legates, J. E. (1961)—J. Am. vet. med. Ass. 139: 1207. Koch, P., Fischer, H. and Schumann, H. (1957)— “Erbpathologie der landwirtschaftlichen Haustiere”. 1st end., Parey, Berlin and Hamburg . Louw, J. H. (1959)—Ann. Roy. Coll. Surg. Eng. 25: 209. McGready, T. A., Murphy, E. C. and Twomey, T. (1967)—Irish vet. J. 21: 148. Norrish, J. G. and Rennie, J. C. (1968)—J. Hered. 59: 186. Osborne, J. and Legates, J. E. (1963)—J. Am. ver. med. Ass. 142: 1104. Schlotthauer, C. F. (1955)—J. Am vet. med. Ass. 127: 339. Skewes, A. R. (1962)—Vet. Med. 57: 133. Vogt, D. W. (1967)—J. Anim. Sci. 26: 1002. Citing Literature Volume49, Issue12December 1973Pages 587-588 ReferencesRelatedInformation

The scientific potential of femtosecond x-ray pulses at linac-driven free-electron lasers such as the Linac Coherent Light Source is tremendous. Time-resolved pump-probe experiments require a measure of the relative arrival time of each x-ray pulse with respect to the experimental pump laser. An optical timing system based on stabilized fiber links has been developed for the LCLS to provide this synchronization. Preliminary results show synchronization of the installed stabilized links at the sub-20-femtosecond level. We present details of the implementation at LCLS and potential for future development.

Scott(1) has shown that the rat's thyroid takes up 50 to 200% more radioiodine under the influence of hesperidine methyl chalcone (H.M.C.). It was therefore decided to try this drug in human beings in order to determine its effect upon thyroidal accumulation of radioiodine. This drug is known to suppress the output of I131 through the kidney; probably I131 stays in the body in circulation a long enough time to favor increased uptake by the gland. Method. Nineteen patients having the diagnoses shown in Table I were studied. All of these were considered to be euthyroid except K.E. and O.C. who were judged to be hyper-and hypothyroid respectively . Two periods of tests were done on each patient. These were the first or the patient's control period before the administration of H.M.C. and the second or his testing period following the administration of H.M.C. At the start of the control period, 20 μc I131 was given orally. Thyroid gland uptake measurements were done at 24-hour intervals for 96 hours. After a rest period of three days, the same patient's thyroid uptake was again measured for residual I131 then 1.0 g of H.M.C. mixture in water was ingested. After an hour lapse to allow for effective absorption of the drug the patient ingested 80 μc I131. At 24-hour intervals, for 96 hours, his thyroid gland uptake was measured and due correction for decay and effective half-life was made for the residual I131 uptake from the control period. The tracer dose of 80 μ I131 was large enough to be readily measurable in the presence of residual I131 and thus also to minimize statistical differences between the measurements of the two periods. Results. Studies on the nineteen patients summarized in Table I show that the oral administration of one gram of H.M.C. significantly increases the thyroidal accumulation of I131.

The relative rates of reaction of thiirane and thiirane derivatives with NH3, a series of secondary amines including aziridine, and trimethylamine were determined in the gas phase by means of B3LYP/6-31+G(d)//HF/6-31+G(d) computations and transition state theory. Convergence of the results was selectively tested using the 6-311++G(d,p) basis set. Comparison with MP2/6-31 + G(d)//MP2/6-31G(d) computations was made in model cases. These results are significant in that they supplement the only reported gas-phase experimental study of this type of reaction. The reaction rates of thiirane with secondary amines can best be rationalized by means of an interplay of steric and polarizability effects. While beta-halo substituents retard S(N)2 reactions in solution, both 2-fluorothiirane and its acyclic model react more than l0(6) times faster with NH3 than the unsubstituted compounds in the gas phase. 2-Fluorothiirane was calculated to react with NH3 at C2 by a factor of 0.142 with respect to thiirane itself; attack at C3 was found to be 3.42 x 10(6) times faster than the parent compound. 2-Methylthirane reacts with NH3 at 0. 230 the rate of thiirane with a 12.8-fold regioselectivity for C3. In the reaction of 2,2-dimethylthirane and NH3, this preference for C3 increases to a factor of 124. Ground-state destabilization of cis-2,3-dimethylthiirane is sufficient to account for its calculated rate acceleration with respect to the trans isomer.

A recently demonstrated single-shot measurement of the relative delay between x-ray FEL pulses and optical laser pulses has now been improved to ~10 fs rms error and has successfully been demonstrated for both soft and hard x-ray pulses. It is based on x-ray induced step-like reduction in optical transmissivity of a semiconductor membrane (Si₃N₄). The transmissivity is probed by an optical continuum spanning 450 - 650 nm where spectral chirp provides a mapping of the step in spectrum to the arrival time of the x-ray pulse relative to the optical laser system.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNotes-Preparation of Aromatic Nitramines. ALkaline Nitration Using Phenyllithium as BaseWilliam White, Eugene Wolfarth, Joel Klink, James Kindig, Chester Hathaway, and Dagnija LazdinsCite this: J. Org. Chem. 1961, 26, 10, 4124–4126Publication Date (Print):October 1, 1961Publication History Published online3 July 2002Published inissue 1 October 1961https://doi.org/10.1021/jo01068a612RIGHTS & PERMISSIONSArticle Views105Altmetric-Citations5LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (390 KB) Get e-Alerts Get e-Alerts

The fully optimized structures and relative energies of all possible methoxy-1,3,5-cycloheptatriene (MCHT) isomers have been determined by semiempirical, ab initio, and density functional theory (DFT) molecular orbital calculations. All methods identify the boat conformation of 1-methoxy-1,3,5-cycloheptatriene as the most stable species in this group of compounds. In order to evaluate boat interconversion barriers, optimizations of the planar isomers were also performed. For comparison purposes, we applied the same computational methodologies to boat and planar conformations of 1,3,5-cycloheptatriene (CHT). Among the semiempirical methods, the SAM1 approximation was found to best reproduce the ab initio and DFT results. Examination of rotational energy profiles allowed for identification of the factors controlling the preferred orientations of the methoxy group in these compounds. The calculations predict that methoxy substitution has little influence on the preferred conformation of the seven-membered ring and only a minor impact on the energy required for interconversion of boat conformations through a planar transition structure. Inclusion of electron correlation makes little difference on the calculated relative energies of the MCHT isomers and optimized geometries but significantly improves the computed reaction barriers involved in the CHT hydrogen transfer transition structures.

2-Azidofluorene was synthesized to serve as a specific photoaffinity label in chemical carcinogenesis studies. The drug exhibited little toxicity, and was non-transforming in the C3H 10T12 CL8 cells. When photolysed at 360 nm in water to generate N-hydroxy-2-aminofluorene, then added to the cells, the drug again exhibited little toxicity but was very weakly transforming. When it was irradiated inside the cells cytotoxicity was enhanced greatly. Both Types II and III transformed foci were observed in transformation experiments and were comparable to those obtained with N-acetoxy-2-acetylaminofluorene. Irradiation alone was neither toxic nor transforming. These results suggest that photoaffinity labeling is a promising tool in studying chemical carcinogenesis by bypassing metabolic activation.