Development and Infrared Applications of Chalcogenide Glass Optical Fibers

Chalcogenide glass fibers based on sulphide, selenide, telluride, and their rare earth doped compositions are being actively pursued both at the Naval Research Laboratory in Washington, D.C. (NRL) and worldwide. Great strides have been made in reducing optical losses using improved chem ical purification techniques, but further improvements are needed in both purification and fiberization technology to attain the theoretical optical losses. Despite this, current singlemode and multimode chalcogenide glass fibers are enabling numerous applications. Some of these applications include laser power delivery, chemical sensing, imaging, scanning near field microscopy spectroscopy, fiber infrared (IR) sources lasers, amplifiers, and optical switches. The authors assert that the research and development of chalcogenide glasses will grow in the foreseeable future, especially with respect to improvements the optical quality of the fibers and the performance of the fibers in existing future applications.     

Differential freeze-out and pion interferometry at RHIC from covariant transport theory

Puzzling discrepancies between recent pion interferometry data on Au+Au reactions at square root of s=30 and 200 AGeV from RHIC and predictions based on ideal hydrodynamics are analyzed in terms of covariant parton transport theory. The discrepancies in the R(out)/R(side) ratio are significantly reduced when the finite opacity of the gluon plasma is taken into account. However, the magnitude of the radii is not well accounted for.     

High-p(T) Tomography of d+Au and Au+Au at SPS,RHIC, and LHC

The interplay of nuclear effects on the p(T)>2 GeV inclusive hadron spectra in d+Au and Au+Au reactions at sqrt[s(NN)]=17, 200, and 5500 GeV is compared to leading order perturbative QCD calculations for elementary p+p (p+p) collisions. The competition between nuclear shadowing, Cronin effect, and jet energy loss due to medium-induced gluon radiation is predicted to lead to a striking energy dependence of the nuclear suppression/enhancement pattern in A+A reactions. We show that future d+Au data can be used to disentangle the initial and final state effects.     

Experimental investigation on the effectiveness of sorption energy recovery wheel in ventilation system

The object of this research was to investigate the effectiveness of sorption energy exchanger and the impact of the operational and thermal environmental conditions on their efficiency under steady-state conditions. To achieve this object, a test facility was installed into the Indoor Air Quality and Thermal Comfort Laboratory of BUTE University. A molecular 3Å sieve sorption wheel with high latent effectiveness is integrated into the experimental setup. In this study, the correlation between the sensible, latent, total effectiveness under different ambient air temperature and humidity values and different rotational speeds of the wheel is investigated in detailed by experimental tests.     

Prevalence of Antimicrobial Resistant Bacteria from Conjunctival Flora in an Eye Infection Prone Breed (Saint Bernard)

The conjunctival bacterial resident and opportunistic flora of dogs may represent a major source of dissemination of pathogens throughout the environment or to other animals and humans. Nevertheless, contamination with bacteria from external sources is common. In this context, the study of the antimicrobial resistance (AMR) pattern may represent an indicator of multidrug resistant (MDR) strains exchange. The present study was focused on a single predisposed breed—Saint Bernard. The evaluated animals were healthy, but about half had a history of ocular disease/treatment. The swabs collected from conjunctival sacs were evaluated by conventional microbiological cultivation and antimicrobial susceptibility testing (AST). The most prevalent Gram-positive was Staphylococcus spp.; regardless of the history, while Gram-negative was Pseudomonas spp.; exclusively from dogs with a history of ocular disease/treatment. Other identified genera were represented by Bacillus, Streptococcus, Trueperella, Aeromonas and Neisseria. The obtained results suggest a possible association between the presence of mixed flora and a history of ocular disease/treatment. A high AMR was generally observed (90%) in all isolates, especially for kanamycin, doxycycline, chloramphenicol and penicillin. MDR was recorded in Staphylococcus spp. and Pseudomonas spp. This result together with a well-known zoonotic potential may suggest an exchange of these strains within animal human populations and the environment.     

Numerical errors and chaotic behavior in docking simulations

This work examines the sensitivity of docking programs to tiny changes in ligand input files. The results show that nearly identical ligand input structures can produce dramatically different top-scoring docked poses. Even changing the atom order in a ligand input file can produce significantly different poses and scores. In well-behaved cases the docking variations are small and follow a normal distribution around a central pose and score, but in many cases the variations are large and reflect wildly different top scores and binding modes. The docking variations are characterized by statistical methods, and the sensitivity of high-throughput and more precise docking methods are compared. The results demonstrate that part of docking variation is due to numerical sensitivity and potentially chaotic effects in current docking algorithms and not solely due to incomplete ligand conformation and pose searching. These results have major implications for the way docking is currently used for pose prediction, ranking, and virtual screening.     

Polyisobutylene-Based Thermoplastic Elastomers. I. Synthesis and Characterization of Polystyrene-Polyisobutylene-Polystyrene Triblock Copolymers

Abstract

Polystyrene-polyisobutylene-polystyrene triblock copolymer thermoplastic elastomers have been synthesized by living carbocationic sequential copolymerization using the tert-butyl dicumyl chloride/TiCl₄/methylcyclohexane:methyl chloride (60:40 v:v)/ ?80°C system in the presence of the proton trap 2,6-di-tert-butylpyridine. Structure-property relationships have been examined by varying the M_n of the PIB middle block (39,000 to 156,000) and that of the PSt end-segment (1,000 to 19,000). The tensile strength is controlled by the molecular weight of the PSt segment and independent of the PIB middle block length in the studied range. Phase separation starts when the M_n of the PSt segment reaches ～ 5,000, and it is complete when the M_n reaches ～ 15,000. These triblocks exhibited 23-25 MPa tensile strength, similar to that of styrenic thermoplastic elastomers obtained by anionic polymerization.     

Analysis of Overlapped and Noisy Hydrogen/Deuterium Exchange Mass Spectra

Noisy and overlapped mass spectrometry data hinder the sequence coverage that can be obtained from hydrogen deuterium exchange analysis, and places a limit on the complexity of the samples that can be studied by this technique. Advances in instrumentation have addressed these limits, but as the complexity of the biological samples under investigation increases, these problems are re-encountered. Here we describe the use of binomial distribution fitting with asymmetric linear squares regression for calculating the accurate deuterium content for mass envelopes of low signal or that contain significant overlap. The approach is demonstrated with a test data set of HIV Env gp140 wherein inclusion of the new analysis regime resulted in obtaining exchange data for 42 additional peptides, improving the sequence coverage by 11 %. At the same time, the precision of deuterium uptake measurements was improved for nearly every peptide examined. The improved processing algorithms also provide an efficient method for deconvolution of bimodal mass envelopes and EX1 kinetic signatures. All these functions and visualization tools have been implemented in the new version of the freely available software, HX-Express v2.