Ionization and electron capture in neon K vacancy production from NNe collisions

Our measurements of Ne K and N K X-ray cross sections for N^{3+,4+,5+,6+,7+,} ions incident on a thin Ne target at energies from 9 to 54 MeV indicate that charge exchange plays a minor role compared to ionization in producing Ne K vacancies over that energy range.     

A sensitive technique for detecting chemical changes by AES

The measurement of Auger currents and their associated peak to peak heights from the first derivative spectra has provided the basis for an analysis of the various stages of nitric oxide absorption onto a W(110) surface at room temperature. This chemisorption system is a test case for the method since the nitrogen and oxygen KLL Auger spectra in first derivative form look similar at all stages of adsorption. The results indicate that the method is sensitive to chemical changes in the adsorbate to an extent comparable with XPS.     

Polarization of 22 MeV neutrons elastically scattered from liquid tritium

The asymmetries from elastic scattering of 22.1 MeV incident neutrons was measured for 11 laboratory angles between 40° and 118.5°. The extrema are −60% at 85° (lab) and +98% at 110° (lab).     

Validation of the simultaneous determination of methylprednisolone and methylprednisolone acetate in human plasma by high-performance liquid chromatography.

A reversed-phase high-performance liquid chromatographic procedure was developed that accurately quantitates methylprednisolone (MP) and methylprednisolone acetate (MPA) in human plasma over the range 2.00-50.0 ng/ml. The internal standard, fluorometholone, was added to an aliquot of sodium fluoride-potassium oxalate-derived plasma. Samples were prewashed with hexane and extracted twice with methylene chloride. The extracts were dried with anhydrous sodium sulfate, centrifuged, and the organic layer separated and dried under nitrogen. The samples were reconstituted in mobile phase and washed an additional time with hexane before 100 microliters were injected onto a Beckman/Altex Ultrasphere ODS column with ultraviolet absorbance detection at 254 nm. Composition of the mobile phase was acetonitrile-water-glacial acetic acid (33:62:5, v/v/v). Calibration curves were obtained by unweighted, linear regression of peak-height ratios of MP (or MPA)/internal standard versus theoretical concentrations of MP or MPA using a Hewlett-Packard 3357 Laboratory Automation System. Extraction efficiencies for MP and MPA over the linear range were 86.4 and 84.7%, respectively. This method was successfully implemented for the analysis of specimens generated from a single-dose bioavailability and safety study for a new formulation of Depo-Medrol sterile aqueous suspension.     

Electrically driven multiaxis rotational dynamics of colloidal platelets in nematic liquid crystals

We describe field-induced multiaxis rotations of colloids in a nematic liquid crystal. Anchoring of the nematic director to the colloidal platelet's surface and interplay of dielectric and elastic energies enable robust control over colloid orientation that cannot be achieved in isotropic liquids. Because of the anisotropy of the fluid and the platelike shape of particles, the colloids can be forced to rotate about four different rotational axes even for a fixed direction of the applied field. The time scale of these unexpected voltage-dependent dynamics varies over four orders of magnitude (10?2-102 s) and promises a number of novel electro-optic, photonic, and display applications.     

S‐Nitrosoglutathione‐Based Nitric Oxide‐Releasing Nanofibers Exhibit Dual Antimicrobial and Antithrombotic Activity for Biomedical Applications

The novel use of nanofibers as a physical barrier between blood and medical devices has allowed for modifiable, innovative surface coatings on devices ordinarily plagued by thrombosis, delayed healing, and chronic infection. In this study, the nitric oxide (NO) donor S‐nitrosoglutathione (GSNO) is blended with the biodegradable polymers polyhydroxybutyrate (PHB) and polylactic acid (PLA) for the fabrication of hemocompatible, antibacterial nanofibers tailored for blood‐contacting applications. Stress/strain behavior of different concentrations of PHB and PLA is recorded to optimize the mechanical properties of the nanofibers. Nanofibers incorporated with different concentrations of GSNO (10, 15, 20 wt%) are evaluated based on their NO‐releasing kinetics. PLA/PHB + 20 wt% GSNO nanofibers display the greatest NO release over 72 h (0.4–1.5 × 10^?10 mol mg^?1 min^?1). NO‐releasing fibers successfully reduce viable adhered bacterial counts by ≈80% after 24 h of exposure to Staphylococcus aureus. NO‐releasing nanofibers exposed to porcine plasma reduce platelet adhesion by 64.6% compared to control nanofibers. The nanofibers are found noncytotoxic (>95% viability) toward NIH/3T3 mouse fibroblasts, and 4′,6‐diamidino‐2‐phenylindole and phalloidin staining shows that fibroblasts cultured on NO‐releasing fibers have improved cellular adhesion and functionality. Therefore, these novel NO‐releasing nanofibers provide a safe antimicrobial and hemocompatible coating for blood‐contacting medical devices.     

Ba3V2S4O3: A Mott Insulating Frustrated Quasi‐One‐Dimensional S=1 Magnet

Through a solid‐state reaction, a practically phase pure powder of Ba₃V₂S₄O₃ was obtained. The crystal structure was confirmed by X‐ray single‐crystal and synchrotron X‐ray powder diffraction (P6₃, a=10.1620(2), c=5.93212(1) Å). X‐ray absorption spectroscopy, in conjunction with multiplet calculations, clearly describes the vanadium in charge‐disproportionated V^IIIS₆ and V^VSO₃ coordinations. The compound is shown to be a strongly correlated Mott insulator, which contradicts previous predictions. Magnetic and specific heat measurements suggest dominant antiferromagnetic spin interactions concomitant with a weak residual ferromagnetic component, and that intrinsic geometric frustration prevents long‐range order from evolving.