Reversible haptotropic shift in zirconocene-hexapentaene complexes

Low-valent zirconocene species reacted with 1,1,6,6-tetraalkyl-1,2,3,4,5-hexapentaenes to form both 1-zirconacyclopent-3-ynes and eta2-pi-coordinated complexes according to the alkyl groups (R) and the existence of the neutral ligand (L). Haptotropic interconvertion between these two complexes was observed. It was proposed that double insertion of isocyanide into the Zr-C bond of 1-zirconacyclopent-3-ynes takes place via the isocyanide adduct of the eta2-pi-complex as an intermediate.     

Chemical and Genetic Study of Ligularia cyathiceps in Yunnan Province of China

Root chemicals and evolutionarily neutral DNA regions in L. cyathiceps samples collected in the Zhongdian (Shangrila) County of Yunnan, P. R. China, were examined. Twenty compounds were isolated, including three new ones, 1β,10β‐epoxy‐6β‐(propionyloxy)furanoeremophilan‐9‐one ( 6 ), 1β,10β‐epoxy‐8α‐ethoxyeremophila‐6,11‐diene ( 14 ), and 11αH‐6β‐isobutyryloxy‐1β,10β,7β,8β‐diepoxyeremophilan‐12,8α‐olide ( 15 ). The chemical diversity was found to be limited, with cacalol ( 1 ) and 6‐(acyloxy)furanoeremophilan‐9‐ones ( 4 and/or 5 ) being major components in all the samples. The nuclear ribosomal RNA gene was also found to harbor little variation, although two distinct sequence types were found for the plastid atpB‐rbcL intergenic region.     

Transparent poly(bisphenol A carbonate)-based nanocomposites with high refractive index nanoparticles

Transparent organic-inorganic nanocomposites were successfully synthesized from sulfonic acid-modified poly(bisphenol A carbonate) (SPC) and TiO₂ or ZrO₂ nanoparticles. The dispersibility of nanoparticles was significantly improved by both the surface treatment of nanoparticles with phosphoric acid 2-ethylhexyl esters (PAEH) and the introduction of a sulfonic acid moiety into the PC chain. It was found that in some cases, crystallization of the matrix caused a reduction in transparency. Efficient dispersion of nanoparticles and the absence of crystallization resulted in highly transparent nanocomposites with up to 42 wt% TiO₂ and 50 wt% ZrO₂ nanoparticles. The refractive indices of the nanocomposites based on SPC increased with the increasing amount of nanoparticles. Theoretical equation based on Maxwell-Garnett effective medium theory provided reasonably close estimation of the refractive indices to the experimentally observed values. The prepared nanocomposites had lower thermal stability than the host matrix polymers.     

Creation and application of psychoactive designer drugs data library using liquid chromatography with photodiode array spectrophotometry detector and gas chromatography-mass spectrometry

In order to quickly confirm a potentially hazardous psychoactive designer drug (a compound in which part of the molecular structure of a stimulant or narcotic has been modified), we created a psychoactive drugs data library by performing analysis using liquid chromatography with photodiode array spectrophotometry (LC/PDA) and gas chromatography-mass spectrometry (GC/MS). The data in this library consist of the LC capacity factor (k′) ratios in relation to the internal standard, the ultraviolet (UV) spectra and the MS spectra of 104 compounds. By performing a comparative study of the data in this report with the analytical data for commercial and illegal drug products, it is possible to quickly identify the psychoactive designer drugs in 205 purchased products by using the library. Further, it is possible to analogize the structure of drugs for which there is no matching data in the library using similar data.Furthermore, when structural isomers of controlled substances have detected from the presented library, similarity of their biological effects on human will be predicted, thus leading to regulate their public circulation. Examples of these types of isomers include, for instance, the narcotic 3,4,5-trimethoxyamphetamine (TMA) and its positional isomers 2,4,5-trimethoxyamphetamine (TMA-2) and 2,4,6-trimethoxyamphetamine (TMA-6), or the narcotic 1-(3-chlorophenyl)piperazine (3CPP) and its isomers 1-(o-chlorophenyl)piperazine (2CPP) and 1-(p-chlorophenyl)piperazine (4CPP). Differentiation of these compounds is necessary in regulating them, and we report here the results of a study of a method to confirm these compounds using the present library.     

Tantalum(V) or niobium(V) catalyzed oxidation of sulfides with 30% hydrogen peroxide

Tantalum(V) and niobium(V) are effective catalysts for the oxidation of sulfides with 30% hydrogen peroxide. The reaction of sulfides with 30% hydrogen peroxide catalyzed by tantalum(V) chloride or niobium(V) chloride in acetonitrile, i-propanol or t-butanol selectively provided the corresponding sulfoxides in high yields. The corresponding sulfones are efficiently obtained from the reaction of sulfides with 30% hydrogen peroxide in methanol catalyzed by tantalum(V) or niobium(V).     

Zinc nanowires synthesized on a large scale by a simple carbothermal process

Metallic Zn nanowires have been synthesized by a new carbothermal reduction route in which ZnO and Eucalyptus sp. tar pitch were used as source materials. This simple practical procedure was capable of producing Zn nanowires in large quantities without reoxidation. This process was carried out in inert atmosphere, without vacuum or catalyst, at temperatures (800–900 °C) lower than those required in the carbothermal reduction of ZnO with graphite. A comparative study was performed using graphite that is traditionally used as a ZnO reducer, under the same experimental conditions, however, no reaction was observed. The new process involves the pyrolysis of biopitch to obtain a highly reactive coke and the reduction of ZnO with the release of Zn_(v) for the growth of Zn_(s) nanowires. The resulting Zn nanowires were characterized by X-ray diffractometry, energy-dispersive spectroscopy and scanning electron microscopy. Differential thermal analysis and thermogravimetric analysis coupled with infrared analysis techniques were used in an effort to understand the underlying mechanism and establish the best ratio biopitch/ZnO to be used. This paper presents the characterization of the as-synthesized nanowires and discusses the main reactions involved in their production.     

A fluorous tag-bound fluorescence derivatization reagent, F-trap pyrene, for reagent peak-free HPLC analysis of aliphatic amines

We have developed a novel pre-column fluorescence derivatization reagent for amines, F-trap pyrene. This reagent comprises a fluorescent pyrene moiety, an amine-reactive Marshall linker, and a fluorophilic perfluoroalkyl group known as fluorous tag. When the reagent reacts with aliphatic amines and amino acids to give fluorescent derivatives, the fluorous tag in the reagent is eliminated simultaneously. Therefore, excess unreacted reagents in the derivatization reaction solution still have the fluorous tag and could be removed by fluorous solid-phase extraction selectively before high-performance liquid chromatography (HPLC) analysis. By using this reagent, 13 kinds of aliphatic amine (C₂–C₁₆) derivatives can be separated within 40 min by reversed-phase HPLC with gradient elution. In this chromatogram, unreacted reagents peak at around 28 min, greatly decrease after fluorous solid-phase extraction, and do not interfere with the quantification of each amine. The detection limits (S/N = 3) for examined aliphatic amines are 3.6–25 fmol per 20 μL injection. We have also applied this reagent successfully to the amino acid analysis.

Arc-disjoint in-trees in directed graphs

Given a directed graph D = (V,A) with a set of d specified vertices S = {s ₁,…, s _d } ⊆ V and a function f: S → ℕ where ℕ denotes the set of natural numbers, we present a necessary and sufficient condition such that there exist Σ _i=1 ^d f(s _i ) arc-disjoint in-trees denoted by T _i,1,T _i,2,…, for every i = 1,…,d such that T _i,1,…, are rooted at s _i and each T _i,j spans the vertices from which s _i is reachable. This generalizes the result of Edmonds [2], i.e., the necessary and sufficient condition that for a directed graph D=(V,A) with a specified vertex s∈V, there are k arc-disjoint in-trees rooted at s each of which spans V. Furthermore, we extend another characterization of packing in-trees of Edmonds [1] to the one in our case. Supported by JSPS Research Fellowships for Young Scientists. Supported by the project New Horizons in Computing, Grand-in-Aid for Scientific Research on Priority Areas, MEXT Japan.     

Partial regularity results up to the boundary for harmonic maps into a Finsler manifold

We study the energy functional for maps from a Riemannian m-manifold M   into a Finsler space N=(Rn,F)$N=({\mathbb{R}}^n,F)$. Under the restriction 2?m?4$2?m?4$, we prove the full Hölder regularity of weakly harmonic maps (i.e., weak solutions of its Euler–Lagrange equation) from M to N   in the case that the Finsler structure F(u,X)$F(u,X)$ depends only on vectors X, and a partial Hölder regularity of energy minimizing maps in general cases.