Struktur und Reaktivität heterosubstituierter Nitrile. XVI[1]. Kinetik und Mechanismus der Arylcyanatbildung aus Bromcyan und Phenolen

Structure and Reactivity of Heterosubstituted Nitriles. XVI. Kinetics and Mechanism of the Formation of Arylcyanates from Cyanogen Bromide and Phenoles The first-order and second-order rate constants of the reaction of cyanogen bromide with phenoles in the presence of tertiary aliphatic amines were determined in absolute acetone. The first step of the reaction is the nucleophilic attack of the tertiary amine at the cyanogen bromide. By a fast equilibrium reaction an N-cyano-N,N,N-trialkylammonium bromide is formed, which is attacked by the phenol as a nucleophile or dissociates in the slowest steps of the reaction. The nucleophilicity and the steric hinderance of the tertiary amine, and the nucleophilicity of the phenole as well determine, which of these reactions is favoured.     

Compound Heterozygous FKTN Variants in a Patient with Dilated Cardiomyopathy Led to an Aberrant α-Dystroglycan Pattern

Fukutin encoded by FKTN is a ribitol 5-phosphate transferase involved in glycosylation of α-dystroglycan. It is known that mutations in FKTN affect the glycosylation of α-dystroglycan, leading to a dystroglycanopathy. Dystroglycanopathies are a group of syndromes with a broad clinical spectrum including dilated cardiomyopathy and muscular dystrophy. In this study, we reported the case of a patient with muscular dystrophy, early onset dilated cardiomyopathy, and elevated creatine kinase levels who was a carrier of the compound heterozygous variants p.Ser299Arg and p.Asn442Ser in FKTN. Our work showed that compound heterozygous mutations in FKTN lead to a loss of fully glycosylated α-dystroglycan and result in cardiomyopathy and end-stage heart failure at a young age.     

IKKγ/NEMO Localization into Multivesicular Bodies

The NF-κB pathway is central pathway for inflammatory and immune responses, and IKKγ/NEMO is essential for NF-κB activation. In a previous report, we identified the role of glycogen synthase kinase-3β (GSK-3β) in NF-κB activation by regulating IKKγ/NEMO. Here, we show that NEMO phosphorylation by GSK-3β leads to NEMO localization into multivesicular bodies (MVBs). Using the endosome marker Rab5, we observed localization into endosomes. Using siRNA, we identified the AAA-ATPase Vps4A, which is involved in recycling the ESCRT machinery by facilitating its dissociation from endosomal membranes, which is necessary for NEMO stability and NF-κB activation. Co-immunoprecipitation studies of NEMO and mutated NEMO demonstrated its direct interaction with Vps4A, which requires NEMO phosphorylation. The transfection of cells by a mutated and constitutively active form of Vps4A, Vps4A-E233Q, resulted in the formation of large vacuoles and strong augmentation in NEMO expression compared to GFP-Vps4-WT. In addition, the overexpression of the mutated form of Vps4A led to increased NF-κB activation. The treatment of cells with the pharmacologic V-ATPase inhibitor bafilomycin A led to a dramatic downregulation of NEMO and, in this way, inhibited NF-κB signal transduction. These results reveal an unexpected role for GSK-3β and V-ATPase in NF-κB signaling activation.     

In vitro behavior of layer-by-layer deposited molecular oligoelectrolyte films on Ti–6Al–4V surfaces

Layer-by-layer self-assembled films of molecular oligoelectrolytes were used to modify Ti–6Al–4V surfaces in order to test their ability as potential drug delivery system. With regard to medical application the in vitro behavior of the modified material was investigated. The Ti–6Al–4V (6% aluminium, 4% vanadium) material was treated in a layer-by-layer (LbL) process with 2, 4, 6 and 8 layers of molecular oligoelectrolytes 1 and 2 and thereby doped with a fluorescent reporter molecule 2. Human osteoblasts were cultured for a period up to 5 days on the modified material. Ti–6Al–4V surfaces without modification were used as control. In order to investigate the in vitro behavior of the coating as well as the influence of components of the coating on osteoblastic cells, respectively, cell proliferation, differentiation and attachment of hFOB cells were observed by means of cell number, osteoblastic gene expression and fluorescence microscopy. Degradation behavior of the OEM (oligoelectrolyte multilayer film) was examined using optical spectroscopy. Measurement data imply that the layer-by-layer coating was successfully assembled on the Ti surface and endures steam sterilization. The fluorescence signal in cell culture medium increased strictly linear with increasing pre-assembled number of layers on the surface. Proliferation rates of the cells in experimental groups did not differ significantly from each other (P ≥ 0.783). Differentiation pattern was not significantly changed by the coating. The fluorescent reporter component of the film was absorbed by osteoblastic cells and was detected by fluorescence microscopy.     

Formation of carbonated apatite particles from a supersaturated inorganic blood serum model

Pathological calcification is common among for instance dialysis patients, and this causes an increase in mortality risk. An elevated serum phosphate concentration among those patients strongly correlates to this increase. In this work investigations of the conditions, composition, crystallinity and morphology of in vitro calcification are performed and related to results from in vivo studies. The study was performed under conditions mimicking physiological ones, i.e. a pH around 7.40, a temperature of 37°C, an ionic strength of 150 mM and ion concentrations close to those in human serum including the effects of elevated phosphate concentrations. The course of precipitation involves an initial precipitate that subsequently re-dissolves to give another precipitate, in accordance with the well-known Ostwald ripening theory. The final bulk precipitate consists of a macroscopically amorphous carbonated apatite. The amorphous apatite is formed from assemblies of spherical particles in the μm range, in turn composed of nano-crystalline needles of about 10 × 100 nm. Even the initially formed precipitate, as well as a small amount of precipitate that occurs on the liquid surface, consist of a carbonated calcium phosphate. The in vitro observed carbonated apatite bears strong resemblance to in vivo cardiovascular calcification known from literature.     

Power to the people: Using learner control to improve trainee reactions and learning in web-based instructional environments.

This experimental study investigated the mechanisms by which learner control influences learning in an e-learning environment. The authors hypothesized that learner control would enhance learning indirectly through its effect on trainee reactions and learner engagement (in particular, off-task attention), such that learners who were more satisfied with the training and devoted more cognitive resources toward the instructional content versus off-task thoughts would possess greater posttraining knowledge. The study also examined the role of individual differences (training motivation and goal orientation) in the prediction of these 2 mediating variables. A sample of 274 undergraduates completed an e-learning program, either with or without interactive, learner control tools. Results suggest that both training satisfaction and off-task attention predicted subsequent learning. Learner control had a positive impact on training satisfaction but was not related to off-task attention. The individual difference variables had a differential impact on the mediating variables. In particular, performance orientation was linked to off-task attention, whereas mastery orientation was found to indirectly influence satisfaction via its direct effect on training motivation. Implications for the design and further study of e-learning are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Charge transport properties in the nanostructured ZnO thin film electrode – electrolyte system studied with time resolved photocurrents

The charge transport in nanoporous ZnO was studied by laser flash induced photocurrent transients. The results are discussed using a diffusion model and compared with previous results on TiO₂. The charge transport was highly dependent on the potential giving apparent diffusion coefficients for the electron ranging from 1×10⁻⁴ to 1×10⁻⁶ cm²/s with an applied bias of +100 and +300 mV vs. Ag/AgCl in ethanol, respectively. The electrolyte was 0.5 M LiClO₄ in ethanol. The potential dependence was much more pronounced for ZnO than for TiO₂. The charge transport was also dependent on the electrolyte giving a linear dependence between the conductivity of the electrolyte and the apparent electronic diffusion coefficient. The dependence of the light intensity was also studied. Intensity-dependent losses were observed.     

弥散强化铸造合金制备工艺的研究

 通过铸造实现弥散强化是不同于传统粉末冶金弥散强化的新途径。本文总结了现有的几种用铸造实现弥散强化的工艺。如何在钢液中获得大量超细的第二相粒子、大量超细的第二相粒子在钢液中的行为、第二相粒子在凝固前沿的行为这三个基本问题决定最终强化的效果。本文对这三个基本问题进行了理论分析,指出了工艺的几个关键点。     

Determination of REE,U,Th,Ba,and Zr in simulated hydrogeological leachates by ICP-AES after matrix solvent extraction

A fast, reliable and precise method for the determination of Ba, Zr, Th, U, La, Ce, Eu, Hf and Gd in leaching solutions containing up to 1 mol/L FeCl3 by inductively coupled plasma-atomic emission spectrometry (ICP-AES) was described. Liquid-liquid extraction with diethyl ether was applied for selective and quantitative extraction of the iron with a decontamination factor of 65000. The study has enabled the determination of rare earth elements, U, Th Ba, and Zr, from the solution with high iron content with detection limits in the range of 1-24 ng/ml and a precision of 0.9%-4.6 % relative standard deviation. The developed method was simple and was adopted for implementation in a glove box for handling radioactive materials.