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1.
Excitation energy transfer from phycobilisomes to photosystem II in high-light adapted cells of Anabaena cylindrica was studied by fluorescence spectroscopy and compared to that of low-light adapted cells. Measurements were made on membrane fragments containing phycobilisomes, photosystem I and II, isolated in 0.75 M K-phosphate. Relative efficiency of 430 to 590 nm light in the excitation of F680 chlorophyll fluorescence was compared in low and high light adapted cells, respectively. The values indicate that light energy absorbed by phycobilisomes is transferred to photosystem II antenna chlorophylls with higher efficiency in high-light adapted cells than in low-light adapted cells. Partial dissociation and uncoupling of energy transfer caused by low ion concentration were different in the membrane fragments isolated from the two kinds of cells and indicated a higher aggregation state of pigment-protein complexes of phycobilisomes in high-light adapted A. cylindrica cells.  相似文献   
2.
Two rapid and popular methods—capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC) have been compared for analysis of cotinine in human urine. Cotinine was analyzed in less than 7 min, with detection limits of 5 and 3.2 ng mL−1 for CE and HPLC, respectively. The performance of the methods was evaluated in terms of sensitivity, specificity, precision, accuracy, and limits of detection and quantification. Calibration plots were linear in the range 50–4,000 ng mL−1, at least, and mean recoveries were satisfactory for both techniques. The methods were successfully used for quantification of cotinine in urine.  相似文献   
3.
Summary A semi-preparative low-pressure liquid-chromatographic procedure using tribenzoylcellulose has been developed for the separation and isolation of the four -bisabolol stereoisomers. Stereochemical assignments were made by HPLC-polarimeter coupling and by using the authentical isomers. This method can be applied to the quality control of chamomile preparations, as it allows the detection of adulterations resulting from admixtures of synthetic -bisabolol. In addition, the isolation of all four -bisabolol stereoisomers from commercially available synthetic -bisabolol has been made possible.  相似文献   
4.
The present work describes the preparation and characterization of a new cobalt(III) porphyrin coordination compound named (chlorido)(nicotinoylchloride)[meso-tetra(para-chlorophenyl)porphyrinato]cobalt(III) dichloromethane monosolvate with the formula [CoIII(TClPP)Cl(NTC)]·CH2Cl2 (4). The single-crystal X-ray molecular structure of 4 shows very important ruffling and waving distortions of the porphyrin macrocycle. The Soret and Q absorption bands of 4 are very red-shifted as a consequence of the very distorted porphyrin core. This coordination compound was also studied by fluorescence and cyclic voltammetry. The efficiency of our four porphyrinic compounds—the H2TClPP (1) free-base porphyrin, the [CoII(TClPP)] (2) and [CoIII(TClPP)Cl] (3) starting materials, and the new Co(III) metalloporphyrin [CoIII(TClPP)Cl(NTC)]·CH2Cl2 (4)—as catalysts in the photochemical degradation was tested on malachite green (MG) dye. The current voltage of complexes 3 and 4 was also studied. Electrical parameters, including the saturation current density (Js) and barrier height (ϕb), were measured.  相似文献   
5.
6.
Differential scanning calorimetry (DSC) has been used for the detection of post-exercise changes in blood serum resulting from participation in the CrossFit (CF) training combined with green tea extract (GTE) supplementation. Blood samples from 20 well-trained men were collected at rest, immediately post-exercise and after 1 h of recovery in two trials: first before and second after CF training combined with GTE or placebo administration in the supplemented (S) and control (C) groups, respectively. Selected muscle damage biomarkers have been compared in different phases of the experiment. A significant increase in blood lactate content has been observed post-exercise in both trials in both participants’ groups. The opposite trends have been noted for the C and S groups in creatine kinase (CK) activity changes recorded during the first to the second trial: an increase in CK for the control and a decrease for the supplemented group in all phases of the experiment: pre-exercise, post-exercise and after recovery. In the second trial, all CK values for the S group have been found significantly lower than the corresponding values recorded in the C group. These results suggest a mitigate effect of GTE supplementation on post-training muscle damage. DSC results did not reveal clear effects of training nor GTE supplementation on serum denaturation transition. However, interesting dependences of thermodynamic parameters describing this transition have been observed in different phases of the experiment. Statistically significant negative correlations have been found between post-training VO2max and post-exercise thermodynamic parameters associated with haptoglobin contribution to serum denaturation transition.  相似文献   
7.
Gaseous products evolved from (NH4)2SO4, NH4HSO4 and NH4NH2SO3 during successive heating and cooling cycles were flushed with inert gas into analyzer Dräger tubes hooked tightly to the terminal port of the DSC cell base. This simple procedure allowed the starting temperature of the decomposition to be determined and the amount of the individual gases in the mixture to be identified and even estimated. NH4NH2SO3 at 523 K in humid air produced HNH2SO3 initially and, on further cycling, (NH4)2SO4 and NH4HSO4 also appeared. The ΔHf values for NH4HSO4 were (kJ mole?1): in an airtight sample holder 12.67, in a dry argon atmosphere 11.93, and in a static air atmosphere 10.92. Endothermic peaks for (NH4)2SO4 and 498 and 411 K represented the incongruent melting point and the polymorphic transition of (NH4)2SO4·NH4HSO4. After the first heating in air to 530 K, (NH4)2SO4 and NH4HSO4 exhibited closely similar cyclic DSC curves. The endothermic peaks at about 393–420 K may be assigned to different combinations of (NH4)2SO4 and NH4HSO4.  相似文献   
8.
Eighteen new 2,4-di-ortho- (meta- and para-) bromo-(chloro- and nitro-)benzylthio-5-bromouracils (and 6-methyluracils) have been prepared. The structures of these compounds were confirmed by spectral (IR, UV/vis, 1H NMR) and elemental analyses. Estimation of pharmacotherapeutic potential has been made for synthesized compounds on the basis of prediction of activity spectra for substances (PASS).  相似文献   
9.
Colourless single crystals of the caffeine adduct of mercurous perchlorate dihydrate, [Hg2(Caf)2](ClO4)2(H2O)2, were grown from aqueous solutions of mercurous perchlorate and caffeine by isothermal evaporation at ambient temperature. The crystal structure (monoclinic, P21/n, Z = 4, a = 1628.0(2), b = 780.4(1), c = 2229.6(3) pm, β = 99.84(1)°, R1(all data) = 0.0894) contains [trans‐Caf‐Hg‐Hg‐Caf]2+ cations with a Hg‐Hg distance of 250.88(6) pm, Hg‐N (bond) distances of 214.4(6) and 215.1(6) pm and Hg‐Hg‐N angles of 176.9(2) and 165.1(2)°, respectively. These cations are attached via weak Hg‐O contacts to dimers which are further arranged to leave large channels into which one crystal water molecule is included. The second water molecule and the two perchlorate anions are weakly attracted to one Hg atom.  相似文献   
10.
Abstract  Modular conditions for the formation of thioureas or pyrimidine-4-one-2-thiones connected to the benzo[b]thiophene, benzene and indole structures were performed. A benzo[b]thiophene isothiocyanate derivative was used as a model to study the condensation with simple aromatic amines and amino-l-sorbose derivative. The construction of pyrimidine-4-one-2-thiones using basic conditions afforded efficiently new heterocyclic aromatics, which were further transformed using the alkylated sulfur as a leaving group in palladium-catalyzed cross-coupling reactions. Graphical abstract     相似文献   
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