Uptake and excretion of total inorganic arsenic by the freshwater alga Chlorella vulgaris

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.     

Improvement of Dispersion and Release Properties of Nifedipine in Suppositories by Complexation with 2-Hydroxypropyl-β-cyclodextrin

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.     

Adsorption characteristics of radionuclides on nickel hexacyanoferrate(ii)

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.     

Medicinal flowers. VI. Absolute stereostructures of two new flavanone glycosides and a phenylbutanoid glycoside from the flowers of Chrysanthemum indicum L.: their inhibitory activities for rat lens aldose reductase

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.     

Bioactive constituents from Chinese natural medicines. XIV. New glycosides of beta-carboline-type alkaloid, neolignan, and phenylpropanoid from Stellaria dichotoma L. var. lanceolata and their antiallergic activities

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.     

Electron spin resonance study on polymerization of alkyl acrylates with n-butyl titanate(IV)–triethylaluminum catalyst

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.     

Analysis of the phase solubility diagram of a phenacetin/competitor/beta-cyclodextrin ternary system, involving competitive inclusion complexation

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.     

Signals for scalar top quark atep collider HERA

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.