1D p–n Junction Electronic and Optoelectronic Devices from Transition Metal Dichalcogenide Lateral Heterostructures Grown by One-Pot Chemical Vapor Deposition Synthesis

Lateral heterostructures of dissimilar monolayer transition metal dichalcogenides provide great opportunities to build 1D in-plane p–n junctions for sub-nanometer thin low-power electronic, optoelectronic, optical, and sensing devices. Electronic and optoelectronic applications of such p–n junction devices fabricated using a scalable one-pot chemical vapor deposition process yielding MoSe₂-WSe₂ lateral heterostructures are reported here. The growth of the monolayer lateral heterostructures is achieved by in situ controlling the partial pressures of the oxide precursors by a two-step heating protocol. The grown lateral heterostructures are characterized structurally and optically using optical microscopy, Raman spectroscopy/microscopy, and photoluminescence spectroscopy/microscopy. High-resolution transmission electron microscopy further confirms the high-quality 1D boundary between MoSe₂ and WSe₂ in the lateral heterostructure. p–n junction devices are fabricated from these lateral heterostructures and their applicability as rectifiers, solar cells, self-powered photovoltaic photodetectors, ambipolar transistors, and electroluminescent light emitters are demonstrated.     

Surface texturing of Mo–V–Te–Nb–O x selective oxidation catalysts

The paper concentrates on the study of Mo–V–Te–Nb oxide mixtures by electron microscopy combined with catalytic investigation of these materials in the partial oxidation of propane. Surface texturing of catalyst particles composed of two phases referred to in the literature as M1 and M2 is revealed by high-resolution transmission electron microscopy of high performing catalysts. The chemical composition of the catalyst surface is modified by treatment in water to obtain a significant increment in yield of acrylic acid. A chemical realization of the site isolation concept recurring on a supramolecular arrangement of catalyst and reactant rather than on atomic site isolation is suggested. A complex Mo–V–Te–Nb–O _x precursor phase carries nanoparticles made from a network of oxoclusters active as catalyst for the conversion of propane to acrylic acid. The designed synthesis of the multi-element oxide bulk and of the surface structure with a different composition than the precursor phase improved the performance by a factor of 4.     

Stereoregular oligomers of methyl methacrylate

Summary Packed column SFC has been found suitable for the rapid and detailed analysis of the isotactic and syndiotactic oligomers of MMA, when the temperature gradient technique was applied and the modifier was employed. Oligomer components from trimer to 20-mer separated completely. The heptamer fraction collected three times by SFC gave the ¹H NMR spectrum of satisfactorily high S/N ratio; the spectrum agreed well with that of the standard sample. Separation by tacticity as well as by molecular weight was observed for the SFC of a mixture of the isotactic and syndiotactic oligomers. The isotactic oligomers had longer retention time than the syndiotactic oligomers of the corresponding degree of polymerization. Part 3: cf. Ute K. Nishimura T, Hatada K, Polym J (1989) 21: 1027     

Innovativer Bayard‐Alpert Sensor mit ausgetrickster Röntgengrenze

Innovative Bayard‐Alpert gauge beats the X‐ray limit In this contribution typical problems that arise when using Bayard‐Alpert (BA) vacuum gauges at UHV and XHV chambers regarding measurement range, accuracy, and reproducibility are discussed. Besides others BA gauges deliver a minor residual current that is inherent to the design of the sensor and that defines the lower measurement limit of the gauge. An investigation of the basic physical processes that contribute to the residual currents in BA gauges yields a novel approach to minimize the residual current in BA gauges directly in the sensor. Experimental results of a new BA gauge with a compensation of the residual current (BARION® XHV) show an extended lower measurement limit by two decades downto XHV and a significantly increased accuracy in the pressure range 10^?9…10^?11 mbar. Due to a respective design, furthermore, an improved reproducibility is ensured.     

Multivariate analysis of C NMR spectra of methacrylate copolymers and homopolymer blends

¹³C NMR spectra of copolymers of methyl methacrylate and tert-butyl methacrylate with various chemical compositions, the homopolymers of the two methacrylates, and blends of the homopolymers with various blend ratios were subjected to principal component analysis. The first and second principal components correlated chemical composition and the randomness of comonomer sequence, respectively. Chemical composition of the copolymers was determined with high accuracy and precision by the partial least-squares regression without assignment of individual resonance peaks.     

Impacts on decision making of executives: Probabilities versus outcomes.

The determinants of decision making of executives are of special interest for companies. For a long time choices have been investigated based on theories that assume an equal impact of expected outcomes and expected probabilities (Von Neumann and Morgenstern 1953, Savage 1954, Kahneman and Tversky 1979). The influence of probabilities in decision processes is, however, questioned by a growing body of research (Rottenstreich and Kivetz 2006, Shapira 1995, March and Shapira 1987, 1992). To monitor the information acquisition process of board members and high-ranking executives in the German insurance industry we conducted 51 personal interviews, which included computer-aided simulations. These simulations clearly and objectively support former statements of executives (Shapira 1995) that they focus more on the amount of decision outcomes than on the corresponding probabilities. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Oxidative metabolism of the mycotoxins alternariol and alternariol-9-methyl ether in precision-cut rat liver slices in vitro

Scope: Monohydroxylation of alternariol (AOH) and alternariol‐9‐methyl ether (AME) has previously been reported as a prominent metabolic route under cell‐free conditions. This pathway gives rise to several catechol metabolites and may therefore be of toxicological relevance. Methods and results: To clarify whether hydroxylation of AOH and AME occurs under in vivo‐like conditions in the presence of conjugation reactions, the metabolism of the Alternaria toxins has now been studied in precision‐cut rat liver slices. Four catechol metabolites of AOH and two of AME, together with several of their O‐methylation products, as catalyzed by catechol‐O‐methyl transferase, were clearly identified after incubation of the liver slices with AOH and AME. These metabolites were predominantly present as conjugates with glucuronic acid and/or sulfate. In preliminary studies with bile duct‐cannulated male rats dosed with AOH by gavage, the four monohydroxylated metabolites of AOH could also be demonstrated in the bile either as catechols or as O‐methyl ethers. Conclusion: These experiments clearly show that AOH and AME undergo catechol formation in vivo and warrant closer examination of the toxicological significance of this metabolic pathway.     

Intervention with polyphenol-rich fruit juices results in an elevation of glutathione S-transferase P1 (hGSTP1) protein expression in human leucocytes of healthy volunteers

Polyphenols are probably antigenotoxic on account of their antioxidant activities and might alter phase I and II enzymes in a way that results in chemoprotection. We investigated the hypothesis that polyphenols enhance expression of glutathione S-transferases (GSTs), which increases carcinogen detoxification and thereby provides protection against oxidative stress. HGSTP1 protein expression and GST polymorphisms were determined in leucocytes obtained during an intervention study with healthy subjects consuming two fruit juices in an 8 wk trial (polyphenol-free run in phase, juice intervention phase, washout phase, second juice intervention phase, each treatment regime lasted for 2 wk). The study had originally shown that juice intervention significantly reduced oxidative DNA damage in leucocytes at week 8 (Bub, A., Watzl, B., Blockhaus, M., Briviba, K. et al., J. Nutr. Biochem. 2003, 14, 90-98). We reanalysed the levels of DNA damage based on GST genotypes. We also treated leucocytes in vitro with mixtures of polyphenols and determined cytotoxicity and expression of 96 genes related to drug metabolism. Key results with leucocytes of the intervention study were that the initial content of hGSTP1 protein was first suppressed at weeks 4 and 6. At week 8, however, hGSTP1 protein expression was significantly increased. HGSTP1 protein levels and DNA damage were inversely correlated (p = 0.005), but there was no difference for cells obtained from subjects with hGSTM1*1 and hGSTM1*0 genotypes, nor was there any difference between cells from subjects consuming the two different juices. The treatment of leucocytes with polyphenol mixtures in vitro did not result in modulated GST gene expression or total GST activity, but in an up-regulation of other biotransformation enzymes (e. g., members of the cytochrome P450 and the sulphotransferase family). In conclusion, in vitro treatment of leucocytes led to a modulated mRNA expression of selected genes, not directly related to oxidative defence systems. In vivo, however, we observed a delayed enhancement of hGSTP1, which could be associated with an initial repression of oxidative DNA damage in leucocytes from human subjects, consuming juices with high levels of polyphenols.