Research Support Instruments (United States)

Sepsis induces a significant loss of circulating IgG, but the underlying mechanism has remained obscure. Here, we identify a previously unrecognized pathogenic axis that directly links bacterial PAMPs to antibody failure. During bacterial sepsis, LPS and PGN potently activate macrophage STAT1, which in turn transcriptionally silences FcRn, collapsing IgG salvage pathways and driving rapid antibody catabolism. This IgG-destabilizing mechanism is strikingly macrophage-specific in the mouse liver and spleen and is conserved in human macrophages. Loss of macrophage FcRn ablates the antibody protection, whereas inhibition of Toll-like receptor 4 (TLR4) or STAT1 signaling potently enhances antibody efficacy in septic mice. These findings uncover a fundamental mechanism of sepsis-induced immunosuppression and reveal a tractable intervention point for rescuing antibody therapeutics against bacterial sepsis.

X-ray Photoelectron Spectroscopy (XPS), a surface-sensitive technique with atomic-scale sensitivity, provides unique insights into the elemental composition, as well as the chemical and electronic states of elements within a material. Given its ability to analyze surfaces with high precision, XPS has become a prominent tool in battery research. Despite its numerous advantages and high reliability, XPS has certain limitations caused by experimental requirements. Factors such as X-ray radiation, high vacuum conditions, and necessity for charge neutralization can potentially alter the sample composition during analysis, leading to misinterpretations of artificial reaction products as genuine battery reactions processes. This concern is particularly critical in the analysis of nonaqueous battery systems containing liquid electrolytes, where volatile components are highly sensitive to vacuum conditions and X-ray exposure. In this study, we systematically investigate the effects of XPS conditions on Lithium bis(Trifluoromethane)Sulfonimide (LiTFSI), a widely used component in nonaqueous battery electrolytes. We demonstrate how prolonged vacuum exposure, application of a low-energy electron flood gun (eFG) and extended X-ray irradiation contribute to the continuous degradation of LiTFSI. Additionally, we propose partial solutions to mitigate these decomposition processes, thereby improving the reliability of XPS measurements in battery research.

Gas-coupled laser acoustic detection (GCLAD) is an unestablished ultrasonic detection technique based on the displacement that a laser beam sustains when intersected by an acoustic wave travelling in a fluid. In the present work, GCLAD for the noncontact detection of ultrasound is applied to identify surface defects on metal plates. Two GCLAD configurations are analysed, each associated with different sensitivities to cracks; specifically, GCLAD exhibits the highest sensitivity when inclined perpendicularly to the ultrasonic propagation direction in the air. The high angular selectivity allows evidencing only specific waves, those directly travelling in the component or reflected by defects. A higher ultrasonic amplitude is highlighted for GCLAD compared to air-coupled probes. The work ultimately demonstrates GCLAD’s major advantage: the possibility of instantly performing an inspection over an entire line, rather than on a point as for traditional transducers.

The resolution of an imaging system can be quantified using the modulation transfer function (MTF) derived from an image with an edge feature. For Earth-viewing satellites, imaging an appropriate terrestrial edge feature is difficult when optical blur from the atmosphere contaminates the MTF. With a sharp edge and no atmosphere, our Moon has provided researchers with an alternative by deriving the line spread function from the lunar edge. The Moon’s surface, however, has features, e.g., craters and seas, that depart from clean step-like behavior, making curve fitting to the data difficult and diminishing the effectiveness of the method. We demonstrate an improvement in which a reflectance (albedo) map of the Moon, created from a mosaic of the U.S. Department of Defense/NASA Clementine images, is used to flatten the surface features before the edge spread function is measured. The objective is to improve the reliability of MTF measurements for on-orbit calibration of the National Oceanic and Atmospheric Administration/NASA Geostationary Operational Environmental Satellite (GOES) weather satellites and similar missions. The technique is applied to the reflective bands of the Advanced Baseline Imager on GOES-16 and GOES-17 weather monitoring satellites.

A theoretical model based on the method of super transition arrays (STA) is used to compute the emissivities, opacities and average ionization states of carbon (C) and polystyrene (CH) plasmas in the warm-dense matter regime in which the coupling constant varies between 0.02 to 2.0. The accuracy of results of STA calculations is assessed by benchmarking against the available experimental data and results obtained using other theoretical methods, assuming that a state of local thermodynamic equilibrium exists in the plasma. In the case of a carbon plasma, the STA method yields spectral features that are in reasonably-good agreement with Dirac-Fock and Hartree-Fock-Slater theories; in the case of CH, we find that STA-derived opacities are very similar to those derived using quantum-molecular-dynamics density-functional theory and Hartree-Fock method down to plasma temperature of about 20 eV. Our calculations also compare favorably with available experimental measurements of Gamboa {\it et al} [High Energy Density Phys. {\bf 11}, 75 (2014)] of the plasma temperature and average ionization state behind a blast wave in a pure carbon foam. Although the STA-computed average-ionization charge state in the rarefaction region appears to be lower than the experimental data, it is within the experimental uncertainty and the discrepancy is nevertheless consistent with results reported using an atomic kinetic model. In addition, we further predict the temperature dependence of average ionization states of CH plasma in the same temperature range as for the carbon plasma.

We report our recent experimental results on CO2 laser acceleration of protons, with a near-critical hydrogen gas target tailored by a Nd:YAG laser-produced blast wave. Monoenergetic protons with energies up to 2.5 MeV were observed.

The physical processes associated with propagation of a high-power laser beam in a dielectric include self-focusing, stimulated Raman scattering, stimulated Brillouin scattering, thermal blooming, and multiphoton and collisional ionization. The interplay between these processes is analyzed using a reduced model consisting of a few differential equations that can be readily solved, enabling rapid variation of parameters and the development of theoretical results for guiding new experiments. The presentation in this paper is limited to propagation of the pump, the Stokes Raman, and the Brillouin pulses, ignoring the anti-Stokes Raman. Consistent with experimental results in the literature, it is found that self-focusing has a dramatic effect on the propagation of high-power laser beams in water. A significant portion of the pump laser energy is transferred to Stokes Raman forward scatter along with a smaller portion to Brillouin backscatter.

We present our recent experimental results of monoenergetic protons accelerated from the interaction of an intense terawatt CO2 laser pulse with a near-critical hydrogen gas target, with its density profile tailored by a hydrodynamic shock. A 5-ns Nd:YAG laser pulse is focused onto a piece of stainless steel foil mounted at the front edge of the gas jet nozzle orifice. The ablation launches a spherical shock into the near-critical gas column, which creates a sharp density gradient at the front edge of the target, with ~ 6X local density enhancement up to several times of critical density within ~<100 microns. With such density profile, we have obtained monoenergetic proton beams with good shot-to-shot reproducibility and energies up to 1.2 MeV.

In direct drive inertial confinement laser fusion, a pellet containing D-T fuel is imploded by ablation arising from absorption of laser energy at its outer surface. For optimal coupling, the focal spot of the laser would continuously decrease to match the reduction in the pellet's diameter, thereby minimizing wasted energy. A krypton-fluoride laser (λ = 248 nm) that incorporates beam smoothing by induced spatial incoherence has the ability to produce a high quality focal profile whose diameter varies with time, a property known as focal zooming. A two-stage focal zoom has been demonstrated on the Nike laser at the Naval Research Laboratory. In the experiment, a 4.4 ns laser pulse was created in which the on-target focal spot diameter was 1.3 mm (full width at half maximum) for the first 2.4 ns and 0.28 mm for the final 2 ns. These two diameters appear in time-integrated focal plane equivalent images taken at several locations in the amplification chain. Eight of the zoomed output beams were overlapped on a 60 μm thick planar polystyrene target. Time resolved images of self-emission from the rear of the target show the separate shocks launched by the two corresponding laser focal diameters.