Ab initio SCF LCAO band structure of poly(SN)

An ab initio SCF LCAO crystal orbital calculation has been performed for the one-dimensional poly(SN) chain. The band structure obtained contains two overlapping (a σ and a π) partially filled bands of a combined width of 6.9 eV.     

A measurement of the Ω− lifetime

In an experiment at the CERN-SPS charged-hyperon beam, a sample of $\text{2500 Ω}{}^{\mathrm{?}}\text{→ ΛK}{}^{\mathrm{?}}$ decays has been collected at Ω^? momenta of 98.5 and 115 GeV/c. The Ω^? lifetime is found to be $\text{τ}{}_{\mathrm{\Omega }}\text{= (0.822 ± 0.028) × 10}{}^{\mathrm{?10}}\text{s}$.     

Ultra-wideband spectral analysis using S2 technology

This paper outlines the efforts to develop an ultra-wideband spectrum analyzer that takes advantage of the broad spectral response and fine spectral resolution (∼25 kHz) of spatial-spectral (S2) materials. The S2 material can process the full spectrum of broadband microwave transmissions, with adjustable time apertures (down to 100 μs) and fast update rates (up to 1 kHz). A cryogenically cooled Tm:YAG crystal that operates on microwave signals modulated onto a stabilized optical carrier at 793 nm is used as the core for the spectrum analyzer. Efforts to develop novel component technologies that enhance the performance of the system and meet the application requirements are discussed, including an end-to-end device model for parameter optimization. We discuss the characterization of new ultra-wide bandwidth S2 materials. Detection and post-processing module development including the implementation of a novel spectral recovery algorithm using field programmable gate array technology (FPGA) is also discussed.     

Recent Studies of Hypernuclei Formation with Electron Beams at MAMI

At the Mainz Microtron MAMI exploratory experiments on the spectroscopy of mesonic weak decays (MWD) of electroproduced Λ-hypernuclei were performed. A unique setup was realized to use the broad momentum-band kaon spectrometer Kaos at zero degree angle with respect to the high-intensity electron beam direction to tag strangeness producing processes. A sample of order 10³ MWD from a beryllium target was collected by the coincidence technique with the high-resolution multi-spectrometer facility of the A1 Collaboration. It is conjectured that this sample contains monochromatic two-body decays from stopped hyperfragment decays as well as a wide momentum distribution of quasi-free produced Λ- and Σ-hyperon decays and three-body decays from hyperfragments. Stopped hyperfragments will be identified as monochromatic peaks in the π ^? momentum spectrum from which their masses can be extracted with a precision of 50 keV/c ².     

Stress relaxation in Fe/Si neutron supermirrors by He irradiation

Magnetic supermirrors are widely used in polarized neutron applications. A key issue in producing these multilayer structures is to avoid residual stress in the layers, which may cause the layers to peel off. In this work He⁺ ion irradiation of 500 keV energy was applied at fluences of 1, 24, 50, 100×10¹⁴ ions/cm² with the aim of reducing residual stress. Structural, magnetic and neutron-optical properties were investigated by grazing incidence high-angle X-ray diffraction, magneto-optical Kerr effect, conversion electron Mössbauer spectroscopy and polarized neutron reflectometry. We find a monotonous decrease of the tensile stress upon irradiation from 1.76 to 0.37 GPa with a coupled decrease of neutron reflectivity at the critical angle and decrease of the maximum polarizing efficiency from 23% to 4% at the highest fluence compared to the as-prepared reference supermirror. The supermirrors exhibit a superposition of uniaxial and fourfold in-plane magnetic anisotropy.     

Biodegradable poly(ethylene carbonate) nanoparticles as a promising drug delivery system with "stealth" potential

The goal of this study was to investigate the suitability of poly(ethylene carbonate) (PEC) nanoparticles as a novel drug delivery system, fulfilling the requirements for a long circulation time. Particles were obtained with a narrow size distribution and nearly neutral zeta potential. Adsorption studies with human plasma proteins revealed that PEC nanoparticles bind much less proteins in comparison to polystyrene (PS) nanoparticles. Cell experiments with fluorescently labeled PEC showed no uptake of the nanoparticles by macrophages. These novel PEC nanospheres with their unique surface properties are a promising candidate for long circulating drug delivery systems in vivo.     

Drug repositioning and pharmacophore identification in the discovery of hookworm MIF inhibitors

The screening of bioactive compound libraries can be an effective approach for repositioning FDA-approved drugs or discovering new pharmacophores. Hookworms are blood-feeding, intestinal nematode parasites that infect up to 600 million people worldwide. Vaccination with recombinant Ancylostoma ceylanicum macrophage migration inhibitory factor (rAceMIF) provided partial protection from disease, thus establishing a "proof-of-concept" for targeting AceMIF to prevent or treat infection. A high-throughput screen (HTS) against rAceMIF identified six AceMIF-specific inhibitors. A?nonsteroidal anti-inflammatory drug (NSAID), sodium meclofenamate, could be tested in an animal model to assess the therapeutic efficacy in treating hookworm disease. Furosemide, an FDA-approved diuretic, exhibited submicromolar inhibition of rAceMIF tautomerase activity. Structure-activity relationships of a pharmacophore based on furosemide included one analog that binds similarly to the active site, yet does not inhibit the Na-K-Cl symporter (NKCC1) responsible for diuretic activity.     

Amphiphilic co-networks with moisture-induced surface segregation for high-performance nonfouling coatings

Herein we report the design of a photocurable amphiphilic co-network consisting of perfluoropolyether and poly(ethylene glycol) segments that display outstanding nonfouling characteristics with respect to spores of green fouling alga Ulva when cured under high humidity conditions. The analysis of contact angle hysteresis revealed that the poly(ethylene glycol) density at the surface was enhanced when cured under high humidity. The nonfouling behavior of nonbiocidal surfaces against marine fouling is rare because such surfaces usually reduce the adhesion of organisms rather than inhibit colonization. We propose that the resultant surface segregation of these materials induced by high humidity may be a promising strategy for achieving nonfouling materials, and such an approach is more important than simply concentrating poly(ethylene glycol) moieties at an interface because the low surface energy has been maintained in our work.     

3He(e,e′pp) and 3He(e,e′pn) reactions at AmPS and MAMI

This paper reports on measurements of the ³He(e,e′pp) reaction measured at AmPS and the ³He(e,e′pn) reaction measured at MAMI. The measurements were performed in similar kinematics to allow a comparison to be made between the cross sections of the two reactions. Results are shown for both reactions together with a comparison for the ³He(e,e′pp) data with continuum Faddeev calculations.