Preparation of (R)-11-hydroxyaporphine directly from (R)-10,11-dihydroxyaporphine ((R)-apomorphine)

A Regioselective synthesis of (R)-11-hydroxyaporphine 2 directly from (R)-10,11-dihydroxyaporphine ((R)-apomorphine, 1 ) is described for the first time. The isopropylidene ketal ring of 10,11-(isopropyl-idenyldioxy)aporphine 5 obtained by the isopropylidenation of apomorphine was regioselectively opened by ten equivalents of trimethylaluminum to give (R)-10-hydroxy-11-tert-butyloxyaporphine 6 . The free 10-hydioxyl position of 6 was triflated with N-pbenyltrifluoromethanesulfonimide and potassium carbonate under reflux to give (R)-10-[(trifluoromethyl)sulfonyloxy]-11-tert-butyloxyaporphine 7 . The reduced product, 11-tert-butyloxyaporphine 8 was prepared from 7 by a palladium-catalyzed hydrogenolysis. The ether cleavage of (R)-11-tert-butyloxyaporphine with 48% hydrobromic acid afforded the desired (R)-11-hydroxyaporphine 2 in good yield.     

Sequential injection analysis system for on-line monitoring of l-cysteine concentration in biological processes

A sequential injection analysis (SIA) system was developed to monitor the concentration of l-cysteine in biological processes on-line. It is based on the redox reaction of l-cysteine with iron(III) in the presence of 1,10-phenanthroline (phen) and the detection of the red-iron(II)-phen complex with a spectrophotometry. The system was fully automated using software written in the LabVIEW™ development environment. A number of system variables such as the flow rate of the carrier buffer solution, the volume ratio of the sample to the reagents, and the reaction coil length, etc., were evaluated to increase the sensitivity and performance of the SIA system. Under partially optimized operating conditions the performance of the SIA system was linear up to a concentration of l-cysteine of 1 mM (R² = 0.998) with a detection limit of 0.005 mM and a sample frequency of 15 hr⁻¹. The SIA system was employed to monitor the concentration of l-cysteine on-line in a continuously stirred reactor and a fermentation process of Saccharomyces cerevisiae. The on-line monitored data were in good agreement with the off-line data measured by a HPLC with a fluorescence detector (n = 15, R² = 09899).     

Factors affecting the catalytic epoxidation of olefins by iron porphyrin complexes and H2O2 in protic solvents

The catalytic epoxidation of cyclohexene by iron(III) porphyrin complexes and H2O2 has been investigated in alcohol solvents to understand factors affecting the catalyst activity in protic solvents. The yields of cyclohexene oxide and the Fe(III/II) reduction potentials of iron porphyrin complexes were significantly affected by the protic solvents, and there was a close correlation between the product yields and the reduction potentials of the iron porphyrin catalysts. The role of alcohol solvents was proposed to control the electronic nature of iron porphyrin complexes that determines the catalyst activity in the epoxidation of olefins by H2O2. We have also demonstrated that an electron-deficient iron porphyrin complex can catalyze the epoxidation of olefins by H2O2 under conditions of limiting substrate with high conversion efficiency in a solvent mixture of CH3OH and CH2Cl2.     

Effective isolation of magnesium lithospermate B and its inhibition of aldose reductase and fibronectin on mesangial cell line

We developed an effective isolation method of magnesium lithospermate B from Salviae miltiorrhizae Radix and found for the first time that magnesium lithospermate B shows strong in vitro inhibition (IC50=0.04 microM) of aldose reductase (AR), 2.5 times than that of clinically used epalrestat (IC50=0.1 microM) and accumulation of fibronectin dose dependently.     

A differential scanning calorimetry study on poly(ethylene terephthalate) isothermally crystallized at stepwise temperatures: multiple melting behavior re-investigated

The multiple melting behavior of poly(ethylene terephthalate) (PET) was investigated with differential scanning calorimetry (DSC) by examining PET samples having been subjected to special schemes of crystallization and annealing treatment at multiple descending temperatures. Upon such step-wise annealing in decreasing temperatures, the existence of doublet melting peaks in addition to a series of multiple minor peaks in the PET has been demonstrated using carefully designed thermal schemes. Using the Hoffman theory, multiple lamellae populations, might be suggested to be simultaneously present in the PET subjected to such thermal treatments. However, direct experimental evidence has yet to be provided. The low-temperature minor crystals simply melt during normal scanning without having time enough to reorganize into higher-melt crystals. Nevertheless, the effect of scanning on non-isothermal crystallization does exist but is primarily confined to the temperature range much below the main melting region where the crystallization of polymer chains can progress at a reasonable rate. At higher temperatures near the main melting region, annealing for extended times is required in order to result in relative changes of the melting endotherms of the upper and lower peaks in the main melting doublet. In all we have shown that interpretations of the multiple melting phenomenon in semicrystalline polymers can be better refined.     

Facile deposition of [60]fullerene and carbon nanotubes on ITO electrode by electrochemical oxidative polymerization of ethylenedioxythiophene

It was found that [60]fullerene encapsulated in p-sulfonatocalix[8]arene and single-walled carbon nanotubes (SWNTs) solubilized by sodium dodecylsulfate can be readily deposited on the ITO electrode by electrochemical oxidative polymerization of ethylenedioxythiophene (EDOT) without chemical modification of these carbon clusters. The driving force for the deposition is an electrostatic interaction between the anionic complexes and the cationic charges of poly(EDOT) formed in the oxidative polymerization process. The surface morphology was thoroughly characterized by scanning electron micrograph: the [60]fullerene/poly(EDOT) film is covered by nano-particles with 20-100 nm diameters whereas the SWNTs/poly(EDOT) film is covered by nanorods with several microm length and ca. 100 nm diameter. The results indicate that the anionic complexes act as nuclei for the polymer growth in the oxidation polymerization. Interestingly, when these modified ITO electrodes were photoirradiated, the appearance of a photocurrent wave was observed. The action spectra showed that the photoexcited energy of [60]fullerene or SWNTs is efficiently collected by the electroconductive poly(EDOT) film and transferred to the ITO electrode.     

Ionizing radiation induces blockade of c-Jun N-terminal kinase-dependent cell death pathway in a manner correlated with p21(Cip/WAF1) induction in primary cultured normal human fibroblasts

During radiotherapy of cancer, neighboring normal cells may receive sub-lethal doses of radiation. To investigate whether such low levels of radiation modulate normal cell responses to death stimuli, primary cultured human fibroblasts were exposed to various doses of gamma-rays. Analysis of cell viability using an exclusion dye propidium iodide revealed that the irradiation up to 10 Gy killed the fibroblasts only to a minimal extent. In contrast, the cells efficiently lost their viability when exposed to 0.5-0.65 mM H(2)O(2). This type of cell death was accompanied by JNK activation, and was reversed by the use of a JNK-specific inhibitor SP600125. Interestingly, H(2)O(2) failed to kill the fibroblasts when these cells were pre-irradiated, 24 h before H(2)O(2) treatment, with 0.25-0.5 Gy of gamma-rays. These cytoprotective doses of gamma-rays did not enhance cellular capacity to degrade H(2)O(2), but elevated cellular levels of p21(Cip/WAF1), a p53 target that can suppress H(2)O(2)-induced cell death by blocking JNK activation. Consistently, H(2)O(2)-induced JNK activation was dramatically suppressed in the pre-irradiated cells. The overall data suggests that ionizing radiation can impart normal fibroblasts with a survival advantage against oxidative stress by blocking the process leading to JNK activation.     

Synthesis and phase relations in the system with garnet-type composition: [Ca1.5GdCe0.5]VIII[ZrFe]VI[Fe x Al3? x ]IVO12

This study was aimed at the synthesis, study of phase relations and characterization of the garnet ([Ca_1.5GdCe_0.5]^VIII[ZrFe]^VI[Fe _x Al_3−x ]^IVO₁₂, x = 0−2) intended as promising matrix for actinides (Pu) immobilization. The optimum temperatures of the fabrication of the garnets ceramics are 1400 °C at x = 2 and 1500 °C at x = 0−1. The garnets lattice parameters and the content of Ce, as an imitator of Pu, increased with the content of iron. It was suggested that the ability of the garnet for incorporation of Pu was closely related to the ionic radii of the elements occupied the four-and six-coordinated sites of the structure.     

Colloidal lithographic nanopatterning via reactive ion etching

We report here a novel colloidal lithographic approach to the fabrication of nonspherical colloidal particle arrays with a long-range order by selective reactive ion etching (RIE) of multilayered spherical colloidal particles. First, layered colloidal crystals with different crystal structures (or orientations) were self-organized onto substrates. Then, during the RIE, the upper layer in the colloidal multilayer acted as a mask for the lower layer and the resulting anisotropic etching created nonspherical particle arrays and new patterns. The new patterns have shapes that are different from the original as a result of the relative shadowing of the RIE process by the top layer and the lower layers. The shape and size of the particles and patterns were dependent on the crystal orientation relative to the etchant flow, the number of colloidal layers, and the RIE conditions. The various colloidal patterns can be used as masks for two-dimensional (2-D) nanopatterns. In addition, the resulting nonspherical particles can be used as novel building blocks for colloidal photonic crystals.     

The study on photoreflectance characteristic of semi-insulating GaAs surface region by its exposure to 6 MeV electron beam

Photoreflectance measurements were performed to investigate the optical properties in the electron beam irradiation semi-insulating GaAs(e-beam irradiation GaAs) and semi-insulating GaAs(SI-GaAs). A considerable increase of the PR amplitudes has been registered after the e-beam irradiation in comparison with the GaAs. It is that result of a higher electron scattering on the lattice defects created by the e-beam.