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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.
Aranka Pilbáth Ilona Felhősi Gyula Tolnai Erika Kálmán 《Journal of Solid State Electrochemistry》2006,10(9):721-729
Due to the toxic and carcinogenic properties of hexavalent chromium ion, the corrosion protection with chromating technique needs replacement. Several environmentally friendly alternative metal pretreatments have already been proposed. One of these methods is the application of self-assembling molecules to form mono- or multilayers on the metal surfaces. These layers can prevent metal dissolution due to their dense and stable structure. The objective of our studies was to protect zinc surface against corrosion, with a thin phosphonate layer. Aqueous solutions of diphosphonic acid with different alkyl chain lengths were applied with different treatment times. The layer formation, stability, and corrosion protection of these films were monitored by electrochemical impedance spectroscopy and the effect of 1,5-diphosphono-pentane (DPP) on zinc was studied by polarization curves. The wetting properties were determined by static contact angle measurement. 1,5-Diphosphono-pentane forms a thin layer, with a pronounced protective ability in neutral aqueous solutions. The application of self-assembling molecules can be a promising method to replace the chromating technique on zinc surface. 相似文献
3.
Piotr Kowalski Marcin Marszałł Ilona Olędzka Wojciech Czarnowski 《Chromatographia》2007,66(5-6):357-361
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
4.
L. Leite D. Jansone M. Fleisher H. Kazhoka J. Popelis N. Veretennikova I. Shestakova I. Domracheva E. Lukevics 《Chemistry of Heterocyclic Compounds》2004,40(6):715-724
The respective 4-(arylvinyl)lactones and compounds of the Michael adduct type were synthesized by the condensation of substituted benzaldehydes with 3-cyano-4,6,6-trimethyl-5,6-dihydro-2-pyranone in the presence of catalytic amounts of sodium hydroxide. It was shown by the semiempirical AM1 method that the indicated products can be formed through one and the same intermediate compound. Some of the synthesized phenylvinyl-5,6-dihydro-2-pyranones have a cytotoxic effect, and this corresponds to the prognosis of the OREX expert system. 相似文献
5.
G. A. Domrachev B. S. Kaverin E. G. Domracheva S. A. Gusev S. Yu. Ketkov V. L. Karnatsevich A. I. Kirillov I. L. Vasilevskaya M. A. Lopatin 《Russian Chemical Bulletin》1994,43(8):1305-1309
Hexagonal close-packed (HCP) C60 and C70 films have been prepared by the Langmuir method and examined by electron microscopy and electron-diffraction analysis. It has been shown that the vacuum deposition of a C60+C70 mixture results in the formation of a film with small sized grains and a distorted C60-HCP structure. The simultaneous deposition of C60 and ferrocene results in the formation of a film with a changed morphology and an electron-diffraction pattern that contains a variable amount of ferrocene depending on the experimental conditions. The electron-diffraction pattern corresponds to the presence of the known molecular complex C60[(C5H5)2Fe]2. The analogous simultaneous deposition of fullerene C60 and cobaltocene results in the formation of a C60 film stable in air and water, which contains carbon and cobalt (from the data of X-ray fluorescence, electron microscopy and microdiffraction). It has a different morphology and different diffraction patterns than pure C60 films and, depending on the cobaltocene content (relative to that of fullerene), appears to be a fullerite film doped with various amounts of cobaltocenium fullende, which is an ionic compound.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1379–1383, August, 1994.The work was financially supported by the Russian Foundation for Basic Research (Projects 93-03-4676 and 93-03-18368). 相似文献
6.
G. Veinberg R. Bokaldere K. Dikovskaya M. Vorona D. Mucel' Kh. Kazhoka I. Turovskis I. Shestakova I. Kanepe I. Domracheva E. Lukevics 《Chemistry of Heterocyclic Compounds》1998,34(11):1266-1275
By the interaction of heterocyclic thiols with sulfoxides of 6,6-dihydro- and 6-chloropenicillanates, derivatives of 4-heteryldithio-2-azetidinones have been synthesized, as well as products of their cyclization to form 2-heterylthiomethyl-and 2-halomethyl-substituted penicillanates and an ester of 3-chloro-3-methyl-7-chlorocepham-4-carboxylic acid. Also, the desulfurization of 6-chloropenicillanate by Raney nickel has been accomplished. For the substances that have been synthesized, a direct relationship has been established between the intensity of their cytotoxic actionin vitro with respect to tumor cells and the influence of these compounds on the intracellular generation of nitric oxide radicals.Latvian Institute of Organic Synthesis, Riga LV-1006, Translated from Khimiya Geterosiklicheskikh Soedinenii, No. 11, pp. 1494–1503, November, 1998. 相似文献
7.
Kurt Günther Reinhold Carle Ilona Fleischhauer Stefan Merget 《Fresenius' Journal of Analytical Chemistry》1993,345(12):787-790
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
8.
Ilona Konkoly Thege 《Thermochimica Acta》1983,60(2):149-159
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
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.
A. Zablotskaya I. Segal S Germane I. Shestakova I. Domracheva A. Nesterova A. Geronikaki E. Lukevics 《Chemistry of Heterocyclic Compounds》2002,38(7):859-866
Trimethylsilyl ethers of various hydroxyl-containing thiazole derivatives have been synthesized. The psychotropic activity (in vivo) and the cytotoxicity (in vitro on tumor cell lines HT-1080 and MG-22A) of these ethers and of their unsilylated precursors have been studied. It was discovered that the obtained compounds possess a sedative action. A moderate cytotoxic effect was detected for piperidine-containing thiazoles, displayed most strongly in relation to MG-22A cells. 相似文献