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Skutterudite Na1+xFe4P12whiskers were prepared by a new hydrothermal reduction alloying method. The diameter of the whisker is about 0.5−4 μm and its L/D ratio is about 10−20. Heating temperature and time can control the diameter and length of the skutterudite whisker. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), electronic diffraction (ED), and X-ray fluorescence analysis have been employed to characterize the products. XRD and ED revealed that the whiskers obtained at 200 °C are cubic skutterudite with a= 7.7995 Å. X-ray fluorescence analysis proved that there are sodium atoms in the skutterudite structure. The possible formation mechanism of Na1+xFe4P12is proposed.

Gold nanoparticles are a kind of nanomaterials that have received great interest in field of biomedicine due to their electrical, mechanical, thermal, chemical and optical properties. With these great potentials came the consequence of their interaction with biological tissues and molecules which presents the possibility of toxicity. This paper aims to consolidate and bring forward the studies performed that evaluate the toxicological aspect of AuNPs which were categorized into in vivo and in vitro studies. Both indicate to some extent oxidative damage to tissues and cell lines used in vivo and in vitro respectively with the liver, spleen and kidney most affected. The outcome of these review showed small controversy but however, the primary toxicity and its extent is collectively determined by the characteristics, preparations and physicochemical properties of the NPs. Some studies have shown that AuNPs are not toxic, though many other studies contradict this statement. In order to have a holistic inference, more studies are required that will focus on characterization of NPs and changes of physical properties before and after treatment with biological media. So also, they should incorporate controlled experiment which includes supernatant control Since most studies dwell on citrate or CTAB-capped AuNPs, there is the need to evaluate the toxicity and pharmacokinetics of functionalized AuNPs with their surface composition which in turn affects their toxicity. Functionalizing the NPs surface with more peculiar ligands would however help regulate and detoxify the uptake of these NPs.

Three phospholipase Ds (PLDs; EC 3.1.4.4) have been cloned from Arabidopsis, and they exhibit two distinct types of activities: polyphosphoinositide-requiring PLDbeta and PLDgamma, and polyphosphoinositide-independent PLDalpha. In subcellular fractions of Arabidopsis leaves, PLDalpha and PLDgamma were both present in the plasma membrane, intracellular membranes, mitochondria, and clathrin-coated vesicles, but their relative levels differed in these fractions. In addition, PLDgamma was detected in the nuclear fraction. In contrast, PLDbeta was not detectable in any of the subcellular fractions. PLDalpha activity was higher in the metabolically more active organs such as flowers, siliques, and roots than in dry seeds and mature leaves, whereas the polyphosphoinositide-dependent PLD activity was greater in older, senescing leaves than in other organs. PLDbeta mRNA accumulated at a lower level than the PLDalpha and PLDgamma transcripts in most organs, and the expression pattern of the PLDbeta mRNA also differed from that of PLDalpha and PLDgamma in different organs. Collectively, these data demonstrated that PLDalpha, PLDbeta, and PLDgamma have different patterns of subcellular distribution and tissue expression in Arabidopsis. The present study also provides evidence for the presence of an additional PLD that is structurally more closely related to PLDgamma than to the other two PLDs.

DsbC, a periplasmic disulfide isomerase of Gram-negative bacteria, displays about 30% of the activities of eukaryotic protein disulfide isomerase (PDI) as isomerase and as thiol-protein oxidoreductase. However, DsbC shows more pronounced chaperone activity than does PDI in promoting the in vitro reactivation and suppressing aggregation of denatured D-glyceraldehyde-3-phosphate dehydrogenase (GAPDH) during refolding. Carboxymethylation of DsbC at Cys98 decreases its intrinsic fluorescence, deprives of its enzyme activities, but lowers only partly its chaperone activity in assisting GAPDH reactivation. Simultaneous presence of DsbC and PDI in the refolding buffer shows an additive effect on the reactivation of GAPDH. The assisted reactivation of GAPDH and the protein disulfide oxidoreductase activity of DsbC can both be inhibited by scrambled and S-carboxymethylated RNases, but not by shorter peptides, including synthetic 10- and 14-mer peptides and S-carboxymethylated insulin A chain. In contrast, all the three peptides and the two nonnative RNases inhibit PDI-assisted GAPDH reactivation and the reductase activity of PDI. DsbC assists refolding of denatured and reduced lysozyme to a higher level than does PDI in phosphate buffer and does not show anti-chaperone activity in HEPES buffer. Like PDI, DsbC is also a disulfide isomerase with chaperone activity but may recognize different folding intermediates as does PDI.

High quality BaTiO3 thin films have been epitaxially grown on SrTiO3 (100) substrates by pulsed laser deposition (PLD) using a single crystal target. The BaTiO3/YBa2Cu3O7 bilayer staictures have also been grown on LaAlO3(100) substrate by PLD for ferroelectric thin film devices. All the two kinds of thin films were analysed by x-ray diffraction, high resolution transmission electron microscopy and scanning electron microscopy.

The effect of the structure YBa2Cu3O7-x superconducting thin films on microwave surface resistance was investigated. The electon channeling patterns (ECPs) and X-ray experimental results showed that the microwave surface resistanceRs is strongly correlated with the perfection of the thin films. The films were deposited on LaAlO3(100) and YSZ(100) substrates. For thin film withRs of 280µO, the crystallinity of the thin film shown byw-scanning andf-scanning was excellent and the ECPs were very sharp. For thin film with highRs of 98 mO, only bands from the major zone were visible in the ECPs, which suggested poor crystallinity of the film. From this investigation it was shown that the more perfect the thin films, the lower theRs.

The surface morphology and growth mechanism ofc-oriented YBa2Cu3O7 thin films deposited on Y-stabilized zirconia substrate by laser deposition has been investigated with scanning tunneling microscopy. Both screw dislocation and layered island growth processes took place. Surface features such as screw dislocation, steps, subgrain boundaries, holes, and troughs were present, suggesting that they may act as pinning sites for flux lines. A thin layer of nonsuperconducting material with a thickness of a few angstroms is seen on the surface of the film.

We have investigated the superconducting behavior of high-Tc YBa2Cu3O7 (YBCO) thin films containing BaO impure phase produced by pulsed laser deposition. The thin films were characterized by the standard four-probe method, X-ray diffraction (XRD), and scanning electron microscopy (SEM). XRD showed that all these thin films contained BaO impurity, with thec-axis normal to the surface of the substrates. The presence of impurity existed from substrate temperatureTs of 727 to 796°C. When these thin films with BaO impurity were measured under the magnetic fields, it was found that the critical current densityJc increased slightly with increase in magnetic fieldB within the range ofB=500 G, in the case ofB perpendicular to thec-axis of the film.

YBa2Cu3O7 superconducting thin films were deposited onR-plane sapphire substrates with Yttria-stabilized zirconia buffer layer by laser ablation. The structure of the films was characterized by X-ray diffraction. Superconducting transitional temperatures as high as =90 K and critical current densities up to 2.2×106 A/cm2 (77 K) were achieved. The results of Auger depth profile showed that no obvious diffusion occurred between the substrate and the YBa2Cu3O7 thin film.

Superconducting MgB₂ thin films were fabricated on Al₂O₃(0001) and MgO(100) substrates by a two-step method. Boron thin films were deposited by pulsed laser deposition followed by an ex-situ annealing process. Resistance measurements of the deposited MgB₂ films show a T_c of 38.6 K for MgB₂/Al₂O₃ and 38.1 K for MgB₂/MgO. Atomic force microscopy, scanning electron microscopy and x-ray diffraction were used to study the properties of the films. The results indicate that the MgB₂/Al₂O₃ films consist of well-crystallized grains with a highly c-axis-oriented structure while the MgB₂/MgO films have a dense uniform appearance with an unfixed orientation.

A new ligand, 2-(N-diphenylphosphinomethyl-N-cyclohexyl)aminopyridine (NNP), was prepared by the Mannich reaction of HPPh2 with 2-(N-cyclohexyl)aminopyridine and paraformaldehyde. The ligand NNP reacted with Fe(CO)5 to give the monometallic complex trans-Fe(CO)3(NNP)2 (2). The reaction of complex 2 with [Cu(CH3CN)4]⁺[ClO4]^- gave a novel complex 3, [(OC)3Fe(μ-NNP)2Cu]⁺ClO4^-, which has two seven-membered macrocycles and an Fe(0) → Cu(I) donor−acceptor bond. The molecular structure of complex 3 was determined by X-ray single-crystal analysis.

Des-(B25-B30)-hexapeptide-insulin with B23-glycine replaced by D-alanine was prepared by a combination of enzymic and non-enzymic syntheses. The purified product was homogeneous in polyacrylamide-gel electrophoresis and could be crystallized. The biological activity in vivo of crystalline [B23-D-Ala]des-(B25-B30)-hexapeptide-insulin was determined as 58% of that of standard pig insulin (27 i.u./mg).

The semisynthesis of deshexapeptide insulin (DHI) from desoctapeptide insulin (DOI) reported earlier1showed that DHI was biologically active. However, the product was not quite homogeneous, mainly due to the esterification side reaction and the following saponification2. Recently, the catalytic action of trypsin was successfully used in the preparation of human insulin from porcine insulin3. It was also used in the preparation of insulin analogues with substitutions of B24 or B25 phenylalanine by leucine4,5. Here, we report the synthesis of DHI from DOI and glycylphenylalanine through the catalytic action of trypsin. The product, purified by gel filtration and DEAE-Sephadex ion-exchange chromatography, showed insulin activity of 7.5 IU mg−1in vivoand could be obtained in crystalline form.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.