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1.
Arsenic-tolerant freshwater alga Chlorella vulgaris which had been collected from an arsenicpolluted environment were tested for uptake and excretion of inorganic arsenic. Approximately half the quantity of arsenic taken up by C. vulgaris was estimated to be adhered to the extraneous coat (10 wt %) of the cell. The remainder was bioaccumulated by the cell. Both adhered and accumulated arsenic concentrations increased with an increase in arsenic(V) concentration of the aqueous phase. Arsenic(V) accumulation was affected by the growth phse: arsenic was most actively accumulated when the cell was exposed to arsenic during the early exponential phase and then accumulation decreased with an increase in culture time exposed to arsenic. The alga grew well in the modified Detmer (MD) medium containing 1 mg As(III) dm?3 and the growth curve was approximated by a ‘logistic equation’. Arsenic(III) was accumulated up to the second day of the culture time and arsenic(III) accumulation decreased with an increase in the culture time after that. Arsenic accumulation was also largely affected by various nutrients, especially by managanese, iron and phosphorus compounds. A modified MD medium with the three nutrients was proposed for the purpose of effective removal of arsenic from the aqueous phase. Using radioactive arsenate (Na2H74AsO4), the arsenic accumulated was found to be readily excreted under conditions which were unfavourable for the multiplication of C. vulgaris. 相似文献
2.
Katsunori Nishimura Rie Hidaka Fumitoshi Hirayama Hidetoshi Arima Kaneto Uekama 《Journal of inclusion phenomena and macrocyclic chemistry》2006,54(1-2):85-88
Geometries, electronic properties and NMR-shielding of cucurbit[5]uril, decamethylcucurbit[5]uril, cucurbit[6]uril, cucurbit[7]uril,
and cucurbit[8]uril are investigated with DFT calculations. All molecules are highly symmetrical with a distinct geometric
flexibility. In addition with a characteristic partial charge distribution these findings account for their chemical complex
building ability. 相似文献
3.
4.
The composition of nickel hexacyanoferrate(II) complexes depends on the ratios of sodium hexacyanoferrate(II) and nickel nitrate solutions mixed. The adsorption behavior of nickel hexacyanoferrate(II) is described; acid treatment of Ni2Fe(CN)6 accelerates the adsorption rate of cesium, but does not increase the adsorption capacity. The Ni—Cs exchange ratios of Ni2Fe(CN)6 are discussed. In concentrated salt solutions, the distribution coefficients of 59Fe, 60Co, 65Zn. 137Cs, 95Zr and 144Ce are determined together with those of 85Sr and 106Ru. A simple determination of 137Cs in sea water containing 59Fe, 60Co, 65Zn, 95Zr, 144Ce, 85Sr and 106Ru is described. 相似文献
5.
Matsuda H Morikawa T Toguchida I Harima S Yoshikawa M 《Chemical & pharmaceutical bulletin》2002,50(7):972-975
Two new flavanone glycosides, (2S)- and (2R)-eriodictyol 7-O-beta-D-glucopyranosiduronic acids, and a new phenylbutanoid glycoside, (2S, 3S)-1-phenyl-2,3-butanediol 3-O-beta-D-glucopyranoside, were isolated from the flowers of Chrysanthemum indicum L. cultivated in China together with eight flavonoids. The absolute stereostructures of the new compounds were determined on the basis of chemical and physicochemical evidence. Both of the new flavanone glycosides were found to show inhibitory activity for rat lens aldose reductase. 相似文献
6.
Morikawa T Sun B Matsuda H Wu LJ Harima S Yoshikawa M 《Chemical & pharmaceutical bulletin》2004,52(10):1194-1199
A new beta-carboline-type alkaloidal glycoside, glucodichotomine B, four new neolignan glycosides, dichotomosides A, B, C, and D, and a new phenylpropanoid glycoside, dichotomoside E, were isolated from a Chinese natural medicine, the roots of Stellaria dichotoma L. var. lanceolata. The structures of the new glycosides were determined on the basis of chemical and physicochemical evidence. Among them, dichotomoside D inhibited the release of beta-hexosaminidase (IC(50)=64 microM) as well as tumor necrosis factor-alpha and interleukin-4 (IC(50)=16, 34 microM) in RBL-2H3 cells. These findings suggest that dichotomoside D is more effective against the late-phase reactions in type I allergy than in the immediate phase. 相似文献
7.
Katsuma Hiraki Shigeru Ikeda Shoichi Kaneko Hidefumi Hirai 《Journal of polymer science. Part A, Polymer chemistry》1979,17(8):2363-2369
n-Butyl titanate(IV)–triethylaluminum catalyst at Al/Ti molar ratios greater than 6 polymerizes methyl and n-butyl acrylates at ?78°C. The polymerization system which includes methyl acrylate at ?78°C, gives two ESR signals with g factors of 1.958 and 1.961 that overlap each other. The absorption intensity of the latter signal is approximately proportional to the polymer chain concentration calculated from polymer yield and the molecular weight. The polymerization system at Al/Ti ratios smaller than 3 has no catalytic activity on the polymerization and shows only the ESR signal with the g factor of 1.958. On the basis of these facts the ESR signal with the g factor of 1.961 is attributed to the active growing end of poly(methyl acrylate) with this catalyst. The character of this active growing end is discussed. 相似文献
8.
The competitive inclusion complexations in the ternary phenacetin/competitors/beta-cyclodextrin (beta-CyD) systems were investigated by the solubility method, where m-bromobenzoic acid (m-BBA) and o-toluic acid (o-TA) were used as competitors. The solubility changes of the drug and competitors as a function of beta-CyD concentration in the ternary systems were formulated using their stability constants and intrinsic solubilities. The decrease in solubility of phenacetin by the addition of competitors could be quantitatively simulated by the formulation, when both drug and competitor give A(L) type solubility diagrams. On the other hand, when one of the guests gives a B(S) type solubility diagram, its solubility change was clearly reflected in that of the another guest, i.e., phenacetin gave an A(L) type solubility diagram in the binary phenacetin/beta-CyD system and o-TA gave a B(S) type diagram in the binary o-TA/beta-CyD system, but in the ternary phenacetin/o-TA/beta-CyD system, a new plateau region appeared in the original A(L) type diagram of phenacetin. This was explained by the solubilization theory of Higuchi and Connors. The solubility analysis of the ternary drug/competitor/CyD systems may be particularly useful for determination of the stability constant of a drug whose physicochemical and spectroscopic analyses are difficult, because they can be calculated by monitoring the solubility change of a competitor, without monitoring that of a drug. Furthermore, the present results suggest that attention should be paid to the type of the phase solubility diagram, as well as the magnitude of the stability constant and the solubility of the complex, for a rational formulation design of CyD complexes. 相似文献
9.
Tadashi Kon Tetsuro Kobayashi Shoichi Kitamura Keiichiro Nakamura Shunji Adachi 《Zeitschrift fur Physik C Particles and Fields》1994,61(2):239-246
In the framework of the minimal supersymmetric standard model (MSSM) and theR-parity breaking model (RBM), we investigate production processes of the scalar top (stop) at HERA energies. These models are characterized by the possible existence of the light stop whose mass is lighter than those of the top quark and the other squarks. It is shown that in the MSSM the stop pair production via boson-gluon fusion gives a sizeable cross section and the most serious background $ep \to ec\bar cX$ could be suppressed by appropriate kinematical cuts. We also show that in the RBM the stop is singly produced in the neutral current processes and we have a clear signal as a sharp peak in the Bjorken parameterx distribution of the scattered electron. 相似文献
10.