Enhanced In Vitro Refolding of Soluble Human Glucocorticoid-Induced TNF Receptor-Related Ligand

The glucocorticoid-induced tumor necrosis factor receptor (GITR) is a member of the tumor necrosis factor receptor superfamily. Attachment of GITR to its ligand (GITRL) regulates diverse biological functions, including cell proliferation, differentiation, and survival. In this study, the extracellular region of human GITRL (hGITRL) was cloned, expressed, and purified. The coding sequence of the extracellular region of hGITRL was isolated from human brain cDNA and inserted in pET20b vector. The hGITRL was expressed in Escherichia coli BL21 (DE3) Star at 37 and 25 °C. The majority of the protein was found in inclusion bodies. We identified three important factors for efficient refolding of hGITRL: a ratio of GSH/GSSG, pH, and addition of polyethylene glycol. The renaturated protein was purified by Ni-NTA chromatography. The overall yield of the expression and refolding was higher than 50 mg/l E. coli culture grown at 37 °C. Size exclusion chromatography showed that hGITRL exists as mixture of various multimeric forms in solution. We tested the association of recombinant hGITRL with THP-1 and U937 cell lines and its activity to promote extracellular signal-regulated protein kinase phosphorylation. The results showed that the recombinant protein was biologically active.     

D?→Dπ and D?→Dγ decays: axial coupling and magnetic moment of D? meson

The axial coupling and the magnetic moment of D ^∗-meson or, more specifically, the couplings g_D^*Dpg_{D^{\ast}D\pi} and g_D^*Dgg_{D^{\ast}D\gamma }, encode the non-perturbative QCD effects describing the decays D ^∗→Dπ and D ^∗→Dγ. We compute these quantities by means of lattice QCD with N _f=2 dynamical quarks, by employing the Wilson (“clover”) action. On our finer lattice (a≈0.065 fm) we obtain g_D^*Dp⁺=20±2g_{D^{\ast}D\pi^{+}}=20\pm2, and g_{D^*0 D⁰g}=2.0±0.6 GeV^-1g_{D^{\ast0} D^{0}\gamma}=2.0\pm 0.6~{\rm GeV}^{-1}. This is the first determination of g_{D^*0 D⁰g}g_{D^{\ast0} D^{0}\gamma} on the lattice. We also provide a short phenomenological discussion and the comparison of our result with experiment and with the results quoted in the literature.     

Enhanced conductivity composites for aircraft applications: carbon nanotube inclusion both in epoxy matrix and in carbonized electrospun nanofibers

The potential of carbonized electrospun nanofiber mats to render epoxy resin composites for aircraft applications electrically and thermally more conductive was investigated. The effect of carbon nanotube inclusion both inside the carbon nanofiber and in the epoxy resin matrix material was studied, in order to reveal any synergistic effects of multilevel presence of nanosized reinforcements on the conductivity and mechanical properties. The carbon nanotube inclusion into the carbonized nanofibers increased the electrical conductivity of the samples by 20–50% and the thermal conductivity by approximately three times leading to a higher value than that of the conventional composites. The preparation of layered composites with a conductive upper layer containing nonwoven carbon nanofabric and a load bearing lower layer with conventional unidirectional carbon fiber reinforcement can offer a cost‐effective and weight‐saving solution for the replacement of metal meshes in structural aircraft composites. Copyright © 2014 John Wiley & Sons, Ltd.     

Thermodynamics of Micellization from Heat‐Capacity Measurements

Differential scanning calorimetry (DSC), the most important technique for studying the thermodynamics of structural transitions of biological macromolecules, is seldom used in quantitative thermodynamic studies of surfactant micellization/demicellization. The reason for this could be ascribed to an insufficient understanding of the temperature dependence of the heat capacity of surfactant solutions (DSC data) in terms of thermodynamics, which leads to problems with the design of experiments and interpretation of the output signals. We address these issues by careful design of DSC experiments performed with solutions of ionic and nonionic surfactants at various surfactant concentrations, and individual and global mass‐action model analysis of the obtained DSC data. Our approach leads to reliable thermodynamic parameters of micellization for all types of surfactants, comparable with those obtained by using isothermal titration calorimetry (ITC). In summary, we demonstrate that DSC can be successfully used as an independent method to obtain temperature‐dependent thermodynamic parameters for micellization.     

Development of the HS-SPME-GC-MS/MS method for analysis of chemical warfare agent and their degradation products in environmental samples

After World War II approximately 50,000 tons of chemical weapons were dumped in the Baltic Sea by the Soviet Union under the provisions of the Potsdam Conference on Disarmament. These dumped chemical warfare agents still possess a major threat to the marine environment and to human life. Therefore, continue monitoring of these munitions is essential. In this work, we present the application of new solid phase microextraction fibers in analysis of chemical warfare agents and their degradation products. It can be concluded that the best fiber for analysis of sulfur mustard and its degradation products is butyl acrylate (BA), whereas for analysis of organoarsenic compounds and chloroacetophenone, the best fiber is a co-polymer of methyl acrylate and methyl methacrylate (MA/MMA). In order to achieve the lowest LOD and LOQ the samples should be divided into two subsamples. One of them should be analyzed using a BA fiber, and the second one using a MA/MMA fiber. When the fast analysis is required, the microextraction should be performed by use of a butyl acrylate fiber because the extraction efficiency of organoarsenic compounds for this fiber is acceptable. Next, we have elaborated of the HS-SPME-GC-MS/MS method for analysis of CWA degradation products in environmental samples using laboratory obtained fibers The analytical method for analysis of organosulfur and organoarsenic compounds was optimized and validated. The LOD's for all target chemicals were between 0.03 and 0.65 ppb. Then, the analytical method developed by us, was used for the analysis of sediment and pore water samples from the Baltic Sea. During these studies, 80 samples were analyzed. It was found that 25 sediments and 5 pore water samples contained CWA degradation products such as 1,4-dithiane, 1,4-oxathiane or triphenylarsine, the latter being a component of arsine oil. The obtained data is evidence that the CWAs present in the Baltic Sea have leaked into the general marine environment.     

The helical melamine–Keggin hybrid nanorods: syntheses and characterizations with two strategies,one-step solid-state chemical reaction and experimental solvent diffusion method

Two new Melamine-Keggin hybrid nanorods, MELH-PMo₁₂ and MELH-PW₁₂, for the first time are successfully synthesized by two chemical methods, one-step solid-state chemical reaction method and experimental solvent diffusion method at room temperature. One-step solid-state reactions involve grounded nanorod materials along with grinding of row material and with solvent diffusion method these nanorods synthesized in single crystals form. These compounds crystallized in trigonal space groups P-3. Elemental analysis, infrared spectroscopy, UV spectroscopy and XRD analysis results prove that the samples still possess Keggin type structure. Transmittance electron microscopy and single-crystal X-ray have shown that the samples have nanorod structures.     

A spiro to ansa rearrangement in cyclotriphosphazene derivatives

Nucleophilic substitution reactions of cyclotriphosphazene derivatives having five-membered spiro rings, N(3)P(3)Cl(4)[O(CH(2))(2)X] (X = NH or O) with alkoxides (of tetraethylene glycol and some mono-functional alcohols) give unexpected rearrangements to form stable seven-membered ring ansa compounds, even though crystallographic evidence shows ring distortion and compression of the cyclophosphazene ring. With weaker nucleophiles such as sodium phenoxide and pyrrolidine substitution at a PCl2 group is preferred and no rearrangement takes place. In contrast, reactions of the analogous phosphazenes containing six-membered spiro rings, N(3)P(3)Cl(4)[O(CH(2))(3)X], with all of the above reagents give only normal substitution reactions at the PCl2 moieties and no rearrangement products. The spiro to ansa rearrangements in cyclophosphazenes are remarkable as the reported primary reaction products with the same difunctional reagents HO(CH(2))(2)XH are predominantly spiro, with some dangling and bridging derivatives, but no ansa compounds.     

On suborbital graphs and related continued fractions

In this paper, we study suborbital graphs for congruence subgroup Γ₀(n) of the modular group Γ to have hyperbolic paths of minimal lengths. It turns out that these graphs give rise to a special continued fraction which is a special case of very famous fraction coming out from Pringsheim’s theorem.     

Optimizing Phylogenetic Diversity with Ecological Constraints

Given an edge-weighted tree T{\mathcal {T}} with leaf set X, define the weight of a subset S of X as the sum of the edge-weights of the minimal subtree of T{\mathcal {T}} connecting the elements in S. It is known that the problem of selecting subsets of X of a given size to maximize this weight can be solved using a greedy algorithm. This optimization problem arises in conservation biology where the weight is referred to as the phylogenetic diversity of a taxa set S. Here, we consider the extension of this problem whereby we are only interested in selecting subsets of the taxa set that are ecologically “viable”. Such subsets are specified by an acyclic digraph which represents, for example, a food web. This additional constraint makes the problem computationally hard. In this paper, we analyze the complexity of different variations of the extended problem.