线粒体热化学研究──Ⅳ．鱼类肝脏线粒体代谢的微量热学研究

线粒体热化学研究──Ⅳ．鱼类肝脏线粒体代谢的微量热学研究谭安民，刘义，谢昌礼，屈松生，顾贫，邓凤姣（武汉大学化学系武汉４３００７２）（武汉大学生命科学院武汉）关键词鱼肝脏，线粒体，微量热学，热化学线粒体在能量代谢的过程中，除一部分能量用于合成ＡＴＰ外...     

A new piezoelectric response model for population growth of bacteria

A piezoelectric response model on the population growth of microorganism is proposed. This model is based on a novel population growth model, which has a more obvious ecological meaning and the fact that the series piezoelectric quartz crystal (SPQC) sensor responses to conductivity changes of the medium during the growth of the microorganism. From the response model four parameters can be obtained including the maximum specific growth rate mu(m), saturated population size N(m), and two constants C and K(1). The influence of the parameters on the response curve is discussed in which the influences of mu(m) and N(m) are more obvious. With the proposed model the quantitative determination of bacteria may be more accurate than the frequency detection time (FDT) method. Then the growth of Escherichia coliform (E. coli) monitored with a SPQC sensor is compared with the simulated growth curve obtained by the proposed model and a good agreement is obtained.     

Filamentous growth in activated sludge

Applied Biochemistry and Biotechnology - Bulking and foaming in activated sludge have been associated with filamentous overgrowth. FilamentousNocardia amarae and nonfilamentousPseudomonas...     

稀土丙烯酸盐与8－羟基喹啉三元固态配合物的合成与表征

稀土丙烯酸盐与８－羟基喹啉三元固态配合物的合成与表征李长正，王学智，唐宁，谭民裕（兰州大学化学系兰州７３００００）关键词：稀土，丙烯酸，８－羟基喹琳，三元配合物８－羟基喹琳因其具有优良的配位性能而被广泛应用于金属离子的分离和分析中［１］。文献中有关它...     

Study on the new fluorescence enhancement system of Tb-1,10-bis(2′-carboxylphenyl)-1,4,7,10-tetraoxadecane in silver chloride collosol and its analytical application

A new salicylic-based open-chain crown ether ligand, 1,10-bis(2′-carboxylphenyl)-1,4,7,10-tetraoxadecane (BCPTD) was synthesized. Solutions of its complex with Tb³⁺ can emit the intrinsic fluorescence of Tb³⁺. The fluorescence intensity of the complex in KCl solution was enhanced by the addition of silver(I), leading to a new fluorescence enhancement phenomenon. The spectrofluorimetric determination of traces of silver(I) based on the above phenomenon was carried out. The excitation and emission wavelengths are 298 and 545 nm, respectively. Under optimal conditions, the differential value of fluorescence intensity in the absence and presence of Ag⁺ was proportional to the concentration of silver(I) in the range 0.5-20 μg ml⁻¹. The method was applied to the determination of silver(I) in a standard ore sample. The analytical performance is investigated in detail by using common aromatic carboxylic acids or synthetic analogues of BCPTD as ligands to replace BCPTD. It was found that Tb-aromatic acid complexes did not result in fluorescence enhancement of Tb³⁺ in AgCl collosol. The phenomenon was only observed in Tb(III) with BCPTD or its open-chain crown ether analogues solutions.In addition, the enhancement of the fluorescence intensity of terbium(III) in these complexes depends on the extent of formation of the AgCl collosol.     

The determination of calcium in yttrium oxide by alpha-particle activation analysis

The determination of calcium in yttrium oxide through the⁴⁰Ca(α, p)⁴³Sc reaction was studied, using a post-irradiation radiochemical separation procedure. The half-life of⁴³Sc was determined to be 3.87 hr. The chemical recovery was about 70%. The detection limit was about 10 ppb, for a 30 min irradiation at an alpha-particle beam current of 1 μA (E_α=13.4 MeV) and γ−γ coincidence counting (background counts being<1, cpm), with counting starting at 4 hours after the end of irradiation. Four samples of a batch of yttrium oxide (A.R.) were analyzed, and found to contain 13.9±1.0 ppm of calcium.     

Binding of wogonin to human serum albumin: a common binding site of wogonin in subdomain IIA

The binding of wogonin to human serum albumin (HSA) has been studied by spectroscopic method including circular dichroism (CD), infrared spectra (IR) and fluorescence spectra. The fluorescence properties of HSA were examined in presence of wogonin and the fluorescence intensity of HSA was significantly decreased in the presence of wogonin. The binding parameters of wogonin were studied from the fluorescence decreasing of HSA by the fluoremetric titrations. The Stern-Volmer plots indicated that the binding of wogonin to HSA at 296, 303, 310 K is characterized by one binding site with the binding constant K(S-V) at 1.872 x 10(5), 1.561 x 10(5), 1.392 x 10(5), respectively, which are good agreement with the results from the Scatchard plots. The binding process was exothermic, enthalpy driven and spontaneous, as indicated by the thermodynamic analyses, and the major part of the binding energy is hydrophobic interaction, which were consistent with the result of molecule modelling study, and there are also a numbers of hydrogen bonds between wogonin and HSA. Furthermore, the displacement experiments indicate that wogonin can bind to the subdomain IIA, that is, the site I of HSA, which is also good agreement with the result of molecule modelling study.     

Surface chemistry studies of (CdSe)ZnS quantum dots at the air-water interface

Trioctylphosphine oxide- (TOPO-) capped (CdSe)ZnS quantum dots (QDs) were prepared through a stepwise synthesis. The surface chemistry behavior of the QDs at the air-water interface was carefully examined by various physical measurements. The surface pressure-area isotherm of the Langmuir film of the QDs gave an average diameter of 4.4 nm, which matched very well with the value determined by transmission electron microscopy (TEM) measurements if the thickness of the TOPO cap was counted. The stability of the Langmuir film of the QDs was tested by two different methods, compression/decompression cycling and kinetic measurements, both of which indicated that TOPO-capped (CdSe)ZnS QDs can form stable Langmuir films at the air-water interface. Epifluorescence microscopy revealed the two-dimensional aggregation of the QDs in Langmuir films during the early stage of the compression process. However, at high surface pressures, the Langmuir film of QDs was more homogeneous and was capable of being deposited on a hydrophobic quartz slide by the Langmuir-Blodgett (LB) film technique. Photoluminescence (PL) spectroscopy was utilized to characterize the LB films. The PL intensity of the LB film of QDs at the first emission maximum was found to increase linearly with increasing number of layers deposited onto the hydrophobic quartz slide, which implied a homogeneous deposition of the Langmuir film of QDs at surface pressures greater than 20 mN.m(-1).     

Enantioselective transition metal catalysis directed by chiral cations

Enantioselective transition metal catalysis directed by chiral cations is the amalgamation of chiral cation catalysis and organometallic catalysis. Thus far, three strategies have been revealed: ligand scaffolds incorporated on chiral cations, chiral cations paired with transition metal ‘ate’-type complexes, and ligand scaffolds incorporated on achiral anions. Chiral cation ion-pair catalysis has been successfully applied to alkylation, cycloaddition, dihydroxylation, oxohydroxylation, sulfoxidation, epoxidation and C–H borylation. This development represents an effective approach to promote the cooperation between chiral cations and transition metals, increasing the versatility and capability of both these forms of catalysts. In this review, we present current examples of the three strategies and suggest possible inclusions for the future.

Enantioselective transition metal catalysis directed by chiral cations is the amalgamation of chiral cation catalysis and organometallic catalysis.