Bridged aromatic alkenes for the study of carbocation-π interaction

Toward the goal of gaining further insight into carbocation-π interactions, bridged-ring aromatic alkene model systems are being investigated in which one isomer will permit π complexation of an intramolecular tertiary carbocation with a benzene ring, but the other isomer will not. The syntheses of three sets of such isomers, having, respectively, benzobicyclo[3.2.1]octene, benzobicyclo[2.2.1]heptene, and benzobicyclo[4.2.1]nonene structures, are described.     

Peroxisome quality control and dysregulated lipid metabolism in neurodegenerative diseases

In recent decades, the role of the peroxisome in physiology and disease conditions has become increasingly important. Together with the mitochondria and other cellular organelles, peroxisomes support key metabolic platforms for the oxidation of various fatty acids and regulate redox conditions. In addition, peroxisomes contribute to the biosynthesis of essential lipid molecules, such as bile acid, cholesterol, docosahexaenoic acid, and plasmalogen. Therefore, the quality control mechanisms that regulate peroxisome biogenesis and degradation are important for cellular homeostasis. Current evidence indicates that peroxisomal function is often reduced or dysregulated in various human disease conditions, such as neurodegenerative diseases. Here, we review the recent progress that has been made toward understanding the quality control systems that regulate peroxisomes and their pathological implications.Subject terms: Pexophagy, Neurodegenerative diseases     

The structure, Raman spectra, and force fields of methylbromosilanes CH3SiClnBr3−n (n = 0, 1, 2)

The laser-excited Raman spectra of liquid CH₃SiCl_nBr_3?n (n = 0, 1, 2) were studied. Quantumchemical calculations of these substances with geometry optimization were performed to determine their harmonic force fields and vibrational frequencies. The calculations were made using the HF/6-31G* and HF/6-311++G** approximations and density functional theory at the B3LYP/6-31G* and B3LYP/6-311++G** levels. An interpretation of the spectra was suggested and the calculated force fields were discussed in comparison with the data on related compounds.     

Highly Crystallized Nanometer‐Sized Zeolite A with Large Cs Adsorption Capability for the Decontamination of Water

Nanometer‐sized zeolite A with a large cesium (Cs) uptake capability is prepared through a simple post‐milling recrystallization method. This method is suitable for producing nanometer‐sized zeolite in large scale, as additional organic compounds are not needed to control zeolite nucleation and crystal growth. Herein, we perform a quartz crystal microbalance (QCM) study to evaluate the uptake ability of Cs ions by zeolite, to the best of our knowledge, for the first time. In comparison to micrometer‐sized zeolite A, nanometer‐sized zeolite A can rapidly accommodate a larger amount of Cs ions into the zeolite crystal structure, owing to its high external surface area. Nanometer‐sized zeolite is a promising candidate for the removal of radioactive Cs ions from polluted water. Our QCM study on Cs adsorption uptake behavior provides the information of adsorption kinetics (e.g., adsorption amounts and rates). This technique is applicable to other zeolites, which will be highly valuable for further consideration of radioactive Cs removal in the future.     

Nanocomposite of Platinum Particles Embedded into Nanosheets of Polycarbazole for Methanol Oxidation

Nanoparticles of Pt were successfully electrodeposited onto polycarbazole (PCz) film on a stainless steel (SS‐PCz‐Pt) by chronocoulometry (0.2 C). For comparative purposes, Pt particles were deposited into stainless steel (SS‐Pt) under the same condition. Fourier transform infrared spectroscopy (FT‐IR) results confirmed PCz exists in the SS‐PCz‐Pt composite electrode. X‐ray photoelectron spectroscopy (XPS) results indicated that PCz of SS‐PCz can interact easily with Pt particles. The crystalline behavior and morphology of SS‐PCz‐Pt and SS‐Pt were determined by X‐ray diffraction (XRD) analysis, scanning electron microscopy (SEM), and Transmission Electron Microscopy (TEM). The TEM results indicated that Pt particles disperse more uniformly into the nanosheets of polycarbazole than those of SS film. Catalytic activity and stability for the oxidation of methanol were studied by using cyclic voltammetry and chronoamperometry. A high catalytic current for methanol oxidation (8.04 mA cm^?2 mg^?1) was found for the SS‐PCz‐Pt electrode in comparison to SS‐Pt electrode (5.01 mA cm^?2 mg^?1) at about 0.6 V (vs. Ag/AgCl).     

Comparison of four microwave digestion methods for the determination of selenium in fish tissue by using hydride generation atomic absorption spectrometry

Four microwave digestion methods of fish tissue for selenium determination by hydride generation atomic absorption spectrometry were compared, in which potassium hexacyanoferrate(III) was chosen as a masking agent for eliminating matrix interferences. The results showed that the methods employing HNO(3)/H(2)O(2), HNO(3)/K(2)S(2)O(8)/H(2)O(2) and HNO(3)/H(3)PO(4)/H(2)O(2) digestion media were unreliable. However, the decomposition using the digestion media of HNO(3)/H(2)SO(4)/H(2)O(2) enabled adequate digestion of fish tissue and retention of selenium in a state amenable for determination. Therefore, the digestion procedures with HNO(3)/H(2)SO(4)/H(2)O(2) media are proposed for the determination of selenium in fish tissue by hydride generation atomic absorption spectrometry. The recoveries of the spiked samples investigated ranged from 90 to 102%. The result obtained from analyzing the NIES CRM No. 6 mussel was in good agreement with the reference value (reference value: 1.5 mug/g; found: 1.45 +/- 0.05 mug/g). The limit of detection for selenium was 0.03 mug/g dry mass for a 100 mg sample. The contents of selenium in local fish species investigated ranged from 0.49 to 2.90 mug/g, and the relative standard deviation for the determination of selenium was less than 8%.     

A note on singular D-branes in group manifolds

We develop the classification and systematic construction of all possible untwisted D-branes in Lie groups of A-D-E series. D-branes are classified according to their positions in the maximal torus. We construct all untwisted singular D-branes by the method of iterative deletion in the Dynkin diagram and count their dimensions, which turn out to be always even numbers.     

A simple method to unwrap the geometrically discontinuous phase map and its application in the measurement of IC package

Research on the techniques to unwrap the geometrically discontinuous phase map is an active area during the past decade, various algorithm are developed. Basically, these algorithms need a prior knowledge about the spatial extension of the discontinuity area in the sample for correct phase unwrapping, manual mask is often involved and negate the sense of automatic processing to fringe patterns. More ever, current phase unwrapping algorithms are either computationally complex or highly time consuming. In this paper, a refined method is proposed to deal with the geometrical discontinuity problem in an improved automation sense: suppression of background noise and recognition of discontinuity area in the phase map can be finished in the same time, and discontinuous phase map can be unwrapped in a simple way to avoid the effect of discontinuity area. An example of electronic package with complex shape and structure is used to verify the efficiency of this method.