DiastereoselectiveandEnantioselectiveSynthesisof(1S,2S)-2-Ethyl-1-aminocyclopropaneCarboxylicAcid

During the last decade, 1-aminocyclopropanecarboxylic acid and its derivatives (ACCS) have attracted increasing attention of organic and bioorganic chemists due to their outstanding biological properties, ranging from antimicrobial, insecticidal, plant growth and fruit ripening controls, etc.1. Moreover, the three-membered carbocycle provides building blocks of unprecedented synthetic potential because it undergoes selective ring opening, ring enlargement or cycloaddition reactions2. The mo…     

Sol-gel derived carbon ceramic electrode containing methylene blue-intercalated α-zirconium phosphate micro particles

Methylene blue-intercalated alpha-zirconium phosphate (MBZrP) micro particles in deionized water were deposited onto the surface of graphite powder to prepare graphite powder-supported MBZrP, which was subsequently dispersed into methyltrimethoxysilane-derived gels to yield a conductive composite. The composite was used as electrode material to fabricate a surface-renewable, rigid, leak-free carbon ceramic composite electrode, bulk-modified with methylene blue (MB). In the configuration, alpha-zirconium phosphate was employed as a solid host for MB, which acted as a catalyst. Graphite powder ensured conductivity by percolation, the silicate provided a rigid porous backbone and the methyl groups endowed hydrophobicity and thus limited the wetting section of the modified electrode. Peak currents of the MBZrP-modified electrode were surface-confined at low scan rates but diffusion-controlled at high scan rates. Square-wave voltammetric study revealed that MBZrP immobilized in carbon ceramic matrix presented a two-electron, three-proton redox process in acidic aqueous solution with pH ranged from 0.44 to 2.94. In addition, the chemically modified electrode showed an electrocatalytic activity toward nitrite reduction at +0.15 V ( vs. Ag/AgCl) in acidic aqueous solution (pH=0.44). The linear range and detection limit are 1x10(-6)-4x10(-3) mol x L(-1) and 1.5x10(-7) mol x L(-1), respectively.     

In situ prepared polypyrrole for low humidity QCM sensor and related theoretical calculation

In situ preparation of polypyrrole (Ppy) by photo-polymerization coated on a quartz crystal microbalance (QCM) as a low humidity sensor was reported. Different concentrations of Ppy films say 0 wt.% (as blank), 0.1, 1, and 10 wt.% were investigated to measure humidity concentrations between 14.7 and 5412.5 ppm_v. The adsorption/desorption behavior was also examined at humidity concentration 510.2 ppm_v. The sensitivities of 0, 0.1 and 1 wt.% Ppy films at 51.5 ppm_v were 0.143, 0.219 and 0.427, respectively. For 1 wt.% Ppy, the highest sensitivity was obtained. The slope and correlation coefficients (R²) for 1 wt.% Ppy at the ranges of 14.7–898.6 ppm_v were 0.0646 and 0.9909, respectively. A series of molecular simulations have been carried out to calculate bond energy for the water molecule interaction with Ppy, which was found to be 3 kcal/mol indicating the existence of hydrogen bonding during the sorption process. Based on Langmuir isotherm adsorption assumption, for 0.1 and 1 wt.% Ppy films, the association constants were 2606.30 and 5792.98, respectively. This larger association constant for 1 wt.% Ppy film explains higher sensitivity.     

A pre-irradiation separation procedure based on ion-exchange chromatography for gallium determination in biological and environmental materials by neutron activation analysis

A pre-irradiation separation procedure, for gallium determination in biological and environmental materials by neutron activation analysis (NAA) is reported. The proposed method, based on ion-exchange chromatography, allows to eliminate the radiation risk, while taking the advantages of high sensitivity of NAA. The single comparator method is employed for gallium quantitative evaluation. Since no standard reference materials with certified gallium contents were available, the reliability of the proposed method was extensively investigated by various approaches. Four biological and one environmental standard reference materials, with gallium contents ranging from 54 g/g-3 ng/g, have been analyzed.     

An improved scheme for the identification of antigens recognized by specific antibodies in two-dimensional gel electrophoresis and immunoblotting

This paper describes an improved scheme for the identification of antigens in crude extracts recognized by specific antibodies when analyzed by a combination of two-dimensional gel electrophoresis and immunoblotting. First, protein components in gels are electrophoretically transferred to a polyvinylidene difluoride membrane which does not shrink or change dimensions in organic solvents. The efficiency of transfer and the localization of sample proteins on the membrane are checked and recorded by staining the blotting membrane with Fast Green FCF and recording the profile on a transparency. After blocking and the immunoassay, the results are recorded by photography. The sites of immune reaction are marked and the same membrane is restained briefly with Coomassie Brilliant Blue R-250 for the protein profile. Thus antigens in complex mixtures, recognized by antibodies of interest, can easily be identified from the restained membrane. If the whole protein profile is not well demonstrated, when used in combination with the profile recorded on the transparency, spots appearing on the restained membrane can still be used as useful landmarks in the final unequivocal antigenic identification. This improved scheme circumvents problems arising from membrane shrinkage and difficulties in accurately matching immunoreactive spots by conventional procedures and thus provides an accurate, simple and fast approach in the identification of antigens after immunoblotting.     

Kilogram-scale synthesis of carbon quantum dots for hydrogen evolution,sensing and bioimaging

A facile, low-cost, green, kilogram-scale synthesis of high quality CQDs were synthesized. The throughput of CQDs is 1.4975 kg in one pot and the as-prepared CQDs have a highly crystalline hexagonal structure with remarkable solubility, stability, and biocompatibility. It showed outstanding electrocatalytic activity, Fe³⁺ sensitivity and good biocompatibility.     

Chemistry of O-Benzoquinones and Masked O-Benzoquinones IV. Synthesis of O-Spirodienonelactones from Unsymmetric Catechols

We describe the syntheses of 6, 8-di-tert-butyl-, 7, 9-di-tert-butyl., 6,7-di-n-propyl and 8, 9-di-n-propyl-O-spirodienonelactone from 3, 5-di-tert-butylcatechol and 3, 4-di-n-propylcatechol.     

气相二茂铁双电荷离子的动能谱研究

The unimolecular charge separation reactions of the doubly charged ions FeC_(10)H_(10)~(2+)、FeC_(10)H_9~(2+)、FeC_(10)H_8~(2+) produced in the ion source by electron impact from ferrocene have been studied using Mass analyzed Ion Kinetic Energy Spectrometry (MIKES) technique. From the values of the kinetic energy releases (T), the intercharge distances (R) of the exploding doubly charged ions in their transition structures have been estimated and some structural informations about the transition states can be obtained. The collision induced reactions of the FeC_(10)H_(10)~(2+) ion with Ar have been studied using MIKES, we postulate a new type of continuing reaction which may be "collisional charge separation induced dissociation".     

酰胺型萃取剂N-503的合成

酰胺型萃取剂N-503[N,N-二-(1-甲基庚基)乙酰胺]可以用甲庚醇或2-氯代辛烷为原料来合成。它的重要中间体二-(1-甲基庚基)胺的制备方法有二:一是从甲庚醇制备的方法,将甲庚醇用阮来镍催化,常压氨解,得率95～99％左右;二是从2-氯代辛烷制备,此法需要高压设备,得率35％左右。第一个方法在扩大试验中,产率和产品质量都比较好,是一个较好的制备长碳链仲胺的方法。     

The Adsorption and Thermal Decomposition of CH2CO (CD2CO) on Si(111)-7 × 7

The adsorption and thermal decomposition of ketene on Si(l 11)-7 × 7 were investigated using various surface analysis techniques. When the surface was exposed to ketene at 120 K, two CO stretching modes at 220 and 273 meV appeared in HREELS, corresponding to two adsorbed ketene states. After the sample was annealed at ?250 K, the 273 and the 80 meV peaks vanished, indicating the disappearance of one of the adsorption states by partial desorption of the adsorbate. In a corresponding TPD measurement, a desorption peak for ketene species was noted at 220 K. Annealing the sample at 450 K caused the decomposition of the adsorbate, producing CH_x and O adspecies. Further annealing of the surface at higher temperatures resulted in the breaking of the CH bond, the desorption of H and O species and the formation of Si carbide. The desorption of H at 800 K was confirmed by the appearance of the D₂ (m/e = 4) TPD peak at that temperature when CD₂CO was used instead of CH₂CO.