Design and Performance of an Integrated Analytical Swatch Testing System

Abstract

An integrated swatch testing system for precisely quantifying the resistance of chemical protective materials to permeation and penetration by a chemical weapons agent (CWA) simulant is described. The analytical variability of methodologies currently used by Department of Defense testing laboratories was dramatically reduced by modifying the test cell and experimental procedures while maintaining compatibility with military testing specifications. Utilizing an on-line calibration system, cryogen-free preconcentrator, and flame ionization detector, the integrated system has demonstrated excellent repeatability, reproducibility, and high sampling frequency for a variety of non-porous and air-penetrable swatch samples challenged with methyl salicylate.     

The relationship of microstructure to mechanical properties of Al-, Si-, K-doped tungsten wire

Tungsten wire, commercially doped with aluminium, silicon, and potassium, was obtained from six different manufacturers with a diameter of 0.0063 cm. The tensile strength at 1620 °C, a measurement of the quality of the wire used by the General Electric Company, was determined and found to be different for each wire. Additional samples of wire were annealed at 1620 °C under the same conditions employed for the tensile test. To determine the microstructure, these samples were thinned for transmission electron microscopy along with the wires in the as-drawn condition. The widths of from 75 to 125 subgrains were measured for each sample. In addition, in the annealed samples, the spacing of the strings of potassium bubbles was also determined. It was found that the 1620 °C tensile strength was related to the increase in width of the subgrains during the 1620 °C anneal and that the amount of subgrain widening was determined by the spacing of the strings of bubbles. Hence, the 1620 °C tensile strength was related to the bubble string spacing; the closer together were the strings, the higher was the 1620 °C tensile strength. It was also shown that the grain morphology of the wire, as measured by the stretch or sag of a filament during a stress test, is also determined by the spacing of the strings of potassium bubbles.     

Beam plasma neutron sources based on beam-driven mirror

The design and performance of a relatively low-cost, plasma-based, 14-MeV D-T neutron source for accelerated end-of-life testing of fusion reactor materials are described in this article. An intense flux (up to 5×10¹⁸ n/m²·s) of 14-MeV neutrons is produced in a fully-ionized high-density tritium target (n _e 3×10²¹ m^–3) by injecting a current of 150-keV deuterium atoms. The tritium plasma target and the energetic D⁺ density produced by D⁰ injection are confined in a column of diameter 0.16 m by a linear magnet set, which provides magnetic fields up to 12 T. Energy deposited by transverse injection of neutral beams at the midpoint of the column is conducted along the plasma column to the end regions. Longitudinal plasma pressure in the column is balanced by neutral gas pressure in the end tanks. The target plasma temperature is about 200 eV at the beam-injection position and falls to 5 eV or less in the end region. Ions reach the walls with energies below the sputtering threshold, and the wall temperature is maintained below 740 K by conventional cooling technology.     

Tough thiourethane thermoplastics for fused filament fabrication

Fused filament fabrication (FFF) is the most common form of additive manufacturing. Most FFF materials are variants of commercially available engineering plastics. Their performance when printed can widely vary, thus there is an increasing volume of research on alternative materials with thermal and mechanical performance optimized for FFF. In this work, thiol–isocyanate polymerization is used for the development of a one‐pot synthesis for polythiourethane thermoplastics for tough three‐dimensional (3D) printing applications. The thiol–isocyanate reaction mechanism allows for rapid polymer synthesis with minimal byproduct formation and few limitations on reaction conditions. The resulting elastomer has high toughness and a low melting point, making it favorable for use as a 3D printing filament. The elastomer outperforms commercial filaments in tension when printed. Considering the rapid advancement of additive manufacturing and the limitations of many engineering polymers with the 3D printing process, these results are encouraging for the development of bespoke 3D printing thermoplastics. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45574.     

Crystallization of polyamide 11 during injection molding

The semicrystalline morphology of injection moldings of polyamide 11 (PA 11) prepared using mold temperatures of 25, 50, and 80°C was investigated. Regardless of the mold temperature, position‐resolved X‐ray diffraction (XRD) and polarized‐light optical microscopy (POM) revealed presence of poor/imperfect α‐crystals with an almost hexagonal arrangement of molecular stems in a nonspherulitic superstructure in the skin, and formation of α‐crystals and spherulites in the core. With increasing mold temperature, the thickness of the skin layer decreased, and the perfection of α‐crystals and the spherulite size in the core increased. The experimental observations are discussed in terms of predicted crystallization temperatures, with the prediction based on cooling‐rate simulations for the various parts of the injection moldings using Moldflow^® and analysis of crystallization of the relaxed melt using fast scanning chip calorimetry, XRD, and POM. It is shown that the structure gradient in PA 11 injection moldings can be forecast without considering the effects of shear for this particular polymer. POLYM. ENG. SCI., 58:1053–1061, 2018. © 2017 Society of Plastics Engineers     

Molecular phenotype of Fragile X syndrome: FMRP,FXRPs, and protein targets

Fragile X syndrome (FraX) is one of the most prevalent genetic causes of mental retardation. FraX is associated with an unstable expansion of a polymorphism within the 5' untranslated region of the FMR1 gene. The main consequence of this mutation is a reduction in the levels of the gene product (FMRP). FMRP is an RNA-binding protein with multiple spliced variants (isoforms) and high levels of expression in a variety of tissues, including neurons. In the latter cells, it is localized not only to the perikaryon but also to dendrites and dendritic spines. FMRP belongs to a family of proteins that includes the Fragile X Related Proteins or FXRPs. FXRPs share high homology in their functional domains with FMRP, and also associate with mRNA and components of the protein synthesis apparatus. However, FXRPs do not have the same temporo-spatial pattern of distribution (and other properties) of FMRP. Immunochemical assays have confirmed that a functionally uncompensated FMRP deficit is the essence of the FraX molecular phenotype. Here, we report our preliminary study on FXRPs levels in leukocytes from FraX males. By immunoblotting, we found that a marked reduction in FMRP levels is associated with a modest increase in FXR1P and no changes in FXR2P levels. The consequences of this reduced FMRP expression on protein synthesis, in other words, the identification of FMRP targets, can be studied by different molecular approaches including protein interaction and proteomics methods. By two-dimensional gel electrophoresis, we showed that in FraX leukocytes there is a defect in acetylation that involves prominently the regulatory protein annexin-1. Extension of current studies of the molecular phenotype to more brain-relevant tissue samples, a wider range of proteomics-based methods, and correlative analyses of FMRP homologues and FMRP targets with multiple behavioral measures, will greatly expand our understanding of FraX pathogenesis and it will help to develop and monitor new therapeutic strategies.     

Regional economic growth by policy-induced capital flows: II. Policy simulation results

This second part of the paper refers to a model, described in Part I, that has been designed to analyze alternative allocation strategies of regional economic growth policy: movement of the workers to the jobs (passive factor stocks adjustment) or jobs to the workers (active factor stocks adjustment). After concentrating on the main properties of the model structure, the references of the parameters and initial values to empirical data are discussed. Model results derived on the basis of parameters representative for the case of passive adjustment policy are studied, also extensively taking account of the impacts of parameter variations. Then follows the analysis of simulation results of active adjustment. The main purpose of all calculations is to demonstrate that the model is able to generate reasonable and consistent policy effects. Moreover, with respect to the model and its parameters this paper attempts to contribute to finding a solid standpoint as to the preconditions of a successful active regional economic policy.The author is indebted to Petra Leutloff, Darmstadt, for setting up and running the computer program for the numerical implementation of the model. At later dates numerical results were produced by Georg Zink and Hagen Bobzin, Siegen.     

Crystal structure of interleukin 10 reveals an interferon gamma-like fold

The crystal structure of recombinant human interleukin 10 (rhIL-10) has been determined by X-ray crystallography at 2.0 A resolution. Interleukin 10 is a dimer composed of identical polypeptide chains related by a 2-fold axis. The molecule is predominantly alpha-helical. The main-chain fold resembles that of interferon gamma (IFN-gamma) in which the structural integrity of each domain is dependent on the intertwining of helices from each peptide chain. Comparison of rhIL-10 and IFN-gamma reveals differences in helix lengths and orientations of the 2-fold related domains. Interleukin 10 and IFN-gamma contain several conserved residues in their internal cores which suggest a possible "fingerprint" for detection of other members of this fold.     

Constraint-based and SAT-based diagnosis of automotive configuration problems

We compare the concepts and computation of optimized diagnoses in the context of Boolean constraint based knowledge systems of automotive configuration, namely the preferred minimal diagnosis and the minimum weighted diagnosis. In order to restore the consistency of an over-constrained system w.r.t. a strict total order of the user requirements, the preferred minimal diagnosis tries to keep the most preferred user requirements and can be computed, for example, by the FASTDIAG algorithm. In contrast, partial weighted MinUNSAT solvers aim to find a set of unsatisfied clauses with the minimum sum of weights, such that the diagnosis is of minimum weight. It turns out that both concepts have similarities, i.e., both deliver an optimal minimal correction subset. We show use cases from automotive configuration where optimized diagnoses are desired. We point out theoretical commonalities and prove the reducibility of both concepts to each other, i.e., both problems are FP^NP-complete, which was an open question. In addition to exact algorithms we present greedy algorithms. We evaluate the performance of exact and greedy algorithms on problem instances based on real automotive configuration data from three different German car manufacturers, and we compare the time and quality tradeoff.