晶态氮化碳薄膜的低温合成

The synthesis of carbon nitride films at low temperature has been investigated using pulsed arc discharge from methanol solution with nitrogen atmosphere. Raman spectra and X-ray diffraction (XRD) analysis suggest that crystalline carbon nitride films may be prepared at low substrate temperature (220 ℃). At same time, the substrate temperature has a significantly effect on the nitrogen content and structure of the films. Increasing substrate temperature (300 ℃) would decrease the content of nitrogen in the films and result in a formation of carbon films.     

5-Acyl-4-amino-2-phenyl-1,3-oxazin-6-ones

Intramolecular cyclization of acyl(ethoxycarbonyl)keteneN-benzoylaminals in boiling Ph₂O gives 5-acyl-4-amino-2-phenyl-1,3-oxazin-6-ones.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1322–1323, July, 1995.This study was financially supported by the Russian Foundation for Basic Research (Grant No. 94-03-08964).     

Surface modification of proteins by covalent binding of acrylic polymers

Surface modification of enzymes for a potential use in therapy was obtained with a new type of tailor-made copolymers ofNacryloylmorpholine andN-acryloxysuccinimide. The first monomer was designed to confer solubility on the polymer, whereas the second was used to give it reactivity toward protein amino groups. The reactivity of polymers of different composition towards amino acid derivatives and model proteins, such as catalase and ribonuclease-A, is described. Water soluble and catalytically active enzyme derivatives were obained using copolymers prepared with a mixture of N-acryloxysuccinimide andn-acryloylmorpholine in a 1:99 molar ratio. At increasing molar ratio (3:97, 10:90) extensive crosslinking between polymer and enzymes takes place, yielding insoluble adducts.     

Chiroptical detection. Novel possibilities of its application to enantiomers

Summary Polarimetric and/or circular dichroic detection of enantiomers after liquid chromatography on optically active sorberts has been used for the following purposes: determination of enantiomeric purity in spite of peak overlap, investigation of enantiomerization during chromatography, monitoring of racemizations and recording of circular dichrograms without preparative enrichment of enantiomers. Novel examples for all applications are give. The general prospects for chiroptical detection are discussed.     

Fast chromatographic separation of (−)-menthyl chloroformate derivatives of some chiral drugs,with special reference to amlodipine,on porous graphitic carbon

Summary Enantiomeric separation of (–)-menthyl chloroformate derivatives of some chiral cardioactive drugs, on porous graphitic carbon (PGC), Hypercarb-S, is described. Capacity and separation factors of derivatives of the calcium channel blockers; amlodipine and UK52.829, the -blockers; atenolol, sotalol and propranolol, and mexiletine were studied in different chromatographic systems based on dichloromethane. A high content of a carboxylic acid in the mobile phase was found to decrease the retention and positively affect the stereoselectivity of the derivatives. A mobile phase with dichloromethane, acetonitrile and formic acid gave baseline separation of the enantiomers of amlodipine in less than 8 minutes. Results show that acetic acid and formic acid, may be regarded as strong organic solvents in PGC chromatography with nearly the same elution power as dichloromethane.     

Amino acid overproduction by analog resistant mutants of the nitrogen fixing cyanobacteriumAnabaena sp 287

Two amino acid analog resistant mutants of the cyanobacteriumAnabaena sp 287 were isolated after MNNG mutagenesis.Anabaena ST 16, a mutant resistant to the alanine analog D-α-aminobutyric acid andAnabaena ST 25, another mutant resistant to the histidine analog l,2,4-triazole-3-alanine, released alanine and histidine, respectively, into the medium upon immobilization in alginic acid during diazotrophic growth in fluidized bed reactors. The rates of amino acid production by the mutants were 4.3 μmol mg chl^-1 h^-1 of D-alanine byAnabaena ST 16 and 16.6 μnol mg chl^-1 h^-1 of L-histidine byAnabaena ST 25. Nitrogen fixation by the mutants was not affected by the extracellular amino acid concentration. While the radioactive carbon flow was followed, the parent strain retained 93% of fixed¹⁴C and released only 7% into the medium. On the other hand,Anabaena ST 16 released 13% andAnabaena ST 25 released 29% into the medium. These mutants are beneficial in the production of radioactive amino acids using diazotrophic photobiotechnology.     

金在微电极上的电沉积研究

本工作利用微循环伏安法和阶跃电位法研究在ＡｕＣｌ３的酸性溶液中金在玻碳和铂微电极上的电沉积行为。结果表明，金在微电极上成核所需的过电位较高，但成核几率也高，在所研究的微电极尺寸范围内，金可形成大量的临界单核，且核的生长速率很快。铂微电极上金电沉积的Ｉ－ｔ曲线符合连续成核的模式。     

Intrinsic infrared absorption for carbon–fluorine bonding in fluorinated nanodiamond

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Synthese von (±)-Porantherilidin

The synthesis of the title compound is described in detail.

     

Crystal Structure of a Supramolecular Complex Formed between 1-bromo-2-iodo-tetrafluoroethane and N,N,N′,N′-tetramethyl-ethylenediamine

X-ray analysis has revealed that N,N,N′,N′-tetramethyl-ethylenediamine 1 form donor–acceptor complex 3 with 1-bromo-2-iodo-tetrafluoroethane 2, in which the N X (X = Br, I) distances are longer than the average covalent bond length between X and N, but are also definitively shorter than the sum of the corresponding van der Waals radii of X and N, thus that indicating weak interactions between the nitrogen and bromine or iodine atoms. In our experimental section, a valuable method for recrystallization and collect X-ray data from crystals that easily exhibit decay and can be cracked is reported.