Carbon multi-walled nanotubes grown by HWCVD on a pyroelectric detector

Carbon multi-wall nanotubes (MWNTs) were grown on a lithium niobate (LiNbO₃) pyroelectric detector with a nickel film as the catalyst by hot-wire chemical vapor deposition (HWCVD). Two detectors are documented, each with slightly different deposition conditions. The absolute spectral responsivity of each device was measured from 600 nm to 1800 nm and indicates that the MWNT-coating absorptance is spectrally uniform, with variations of only a few percent. We also discuss growth of MWNTs on LiTaO₃ by CVD and the limitations presented by the Curie temperature of the pyroelectric material.     

Low-temperature conductivity of a two-dimensional disordered semiconductor under power localization conditions

An estimate is given of the temperature dependence of the conductivity under conditions when the Fermi level is in the power localization domain.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 24–26, November, 1982.One of us (V. L. Bonch-Bruevich) is grateful to Dr. M. Pepper for sending a preprint.     

Enzyme-catalyzed synthesis of (R)- and (S)-3-heteroaryl-3-hydroxy-propanoic acids and their derivatives

Starting from the racemic 3-benzofuranyl- and 3-benzo[b]thiophenyl-3-hydroxypropanoic acid ethyl esters as substrates, various multistep enzymatic procedures were developed for the efficient synthesis of the corresponding highly enantiomerically enriched (R)- and (S)-3-heteroaryl-3-hydroxypropanoic acids.     

Green's Functions for Quasi-Hyperbolic Metrics on Degenerating Riemann Surfaces with a Separating Node

In this article, we consider a family of compact Riemann surfaces of genus q 2 degenerating to a Riemann surface with a separating node and many non-separating nodes. We obtain the asymptotic behavior of Green's functions associated to a continuous family of quasi-hyperbolic metrics on such degenerating Riemann surfaces.     

CORRELATION OF ALKALINITY WITH AROMATIZATION SELECTIVITY OF C_6 PARAFFIN OVER Pt/ML(M=Li,Na,K AND Rb)CATALYSTS

The effect of alkaline metals such as I,i, Na, K and Rb on the aromatization of n-C6, paraffin over Pt/ML zeolite catalyst was studied. It was shown that the alkaline cations, especially the Rb with strong basicitv and larger radius, lead Pt particles to disperse well on the surface of L zeolite. A stronger basicity of the modifying cation resulted in higher activity and selectivity to aromatization of n-C6. It is argued that the alkali cations affected the electronic slate of P1. leading to Ptδ-. which caused a decrease of dehvdrogenation activity and an increase of the selectivity to aromatization.     

Growth of Au nanoparticles on phosphorylated zein protein particles for use as biomimetic catalysts for cascade reactions at the oil–water interface

Chemo-enzymatic cascade processes are invaluable due to their ability to rapidly construct high-value products from available feedstock chemicals in a one-pot relay manner. However, they have proven to be challenging because of the mutual inactivation of both catalysts. A conceptually novel strategy based on Pickering interfacial catalysis (PIC) is proposed here to address this challenge. This study aimed to construct a protein-stabilized Pickering system for biphasic cascade catalysis, enabled by phosphorylated zein nanoparticles (ZCPOPs) immobilized in gold nanoparticles (Au NCs). Ultra-small Au NCs, 1–2 nm in diameter, were integrated into ZCPOPs at room temperature. Then, the as-synthesized ZCPOPs–Au NCs were used to stabilize the oil-in-water (o/w) Pickering emulsion. Besides their excellent catalytic activity and recycling ability in a variety of oil phases, ZCPOPs–Au NCs possess unpredictable catalytic activity and exhibit mimicking properties of horseradish peroxidase. Particularly, the cascade reaction is well achieved using a metal catalyst and a biocatalyst at the oil–water interface. The result showed that such a combination of chemo- and biocatalysis improved the catalytic yield more than two times compared with that of sole metal catalysis. This study opened a new avenue to design nanomaterials using the combination of chemo- and biocatalysis in a Pickering emulsion system for multistep syntheses.

A robust chemo- and biocatalytic cascade PIC with a recovery catalyst and a separation product was developed. The results groundbreakingly highlighted the preliminary applications of artificial enzymes and bio-enzymes in a one-pot cascade PIC.     

EPMA and Microstructural Characterization of Yttrium Doped BaTiO3 Ceramics

 Yttrium-doped BaTiO₃ ceramics have been studied as a potential material for positive temperature coefficient resistors (PTCR). The mechanism of Y incorporation into BaTiO₃ plays an important role for displaying good electrical properties. Determination of the amount of yttrium in the BaTiO₃ as well as microstructure characterization of the samples were performed using SEM, EDS and WDS analysis. An optimized trace element WDS quantitative analysis was applied to determine elemental concentrations for Ba, Ti and Y in the samples as accurately as possible. BaTiO₃ and Y₂O₃ were used as standards. Analysis was undertaken using a JEOL JXA 840A electron probe microanalyzer. WDS X-ray intensity measurements were performed under 20 kV, 50 nA beam current and 0.2% preset standard counting deviation (σ_c) using a PET crystal. Measured k-ratios were quantified by ZAF matrix correction. Average results of WDS quantitative analysis showed 20.17 ± 0.08 at % Ti, 19.95 ± 0.09 at % Ba, 0.22 ± 0.03 at % Y, and 59.66 at % O. The results suggest incorporation of yttrium in the BaTiO₃ preferentially at the Ba-sites, however partial incorporation of Y at Ti-sites could not be excluded.     

Determination of the release of hydrolyzed demethylcantharidin from novel traditional chinese medicine-platinum compounds with anticancer activity by gas chromatography

The present paper describes the development of a simple, accurate and reproducible gas chromatographic method for the determination of hydrolyzed demethylcantharidin release from a novel series of traditional Chinese medicine (TCM)-platinum compounds possessing potent anticancer and protein phosphatase 2A (PP2A)-inhibition properties. The salient features of the validated assay were a limit of detection (LOD) of 2 microg/mL, a limit of quantitation (LOQ) of 6 microg/mL, an intra- and inter-day precision of less than 11%, and an accuracy of more than 92%. The developed GC-flame ionization detection (FID) method was successfully utilized for the analysis of hydrolyzed demethylcantharidin, the TCM component that is slowly released from the novel compounds over 24 h, leading to PP2A inhibition. Further structural confirmation was achieved by GC-MS. The GC method is suitable for further mechanistic, pharmacokinetic and metabolic studies of the TCM-Pt compounds that might prove to be new anticancer agents with novel mechanisms of cytotoxic action.