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Sample records for pyrocatechin

  1. Effect of hydrogen and oxygen on stability of expanders and performance of lead/acid batteries

    Energy Technology Data Exchange (ETDEWEB)

    Pavlov, D. (Bulgarian Academy of Sciences, Sofia (Bulgaria). Central Lab. of Electrochemical Power Sources); Gancheva, S. (Bulgarian Academy of Sciences, Sofia (Bulgaria). Central Lab. of Electrochemical Power Sources); Andreev, P. (Bulgarian Academy of Sciences, Sofia (Bulgaria). Central Lab. of Electrochemical Power Sources)

    1993-10-15

    Expanders are organic additives to the negative active mass that increase plate capacity, especially at low temperatures. They operate under constant hydrogen and oxygen attack at strongly negative potentials as a result of which they undergo degradation. This leads to changes in plate capacity, which may limit the life of the battery. The aims of the present work are: (i) to suggest a method for determining the effect of hydrogen, oxygen and the potential on the stability of expanders; (ii) to identify some of the structural groups in organic compounds that exert an efficient expander action. The influence of Velex, Mimosa, Quebraco, Syntan NK (SNK) and EZE-Skitan on the electrochemical characteristics and the life of negative battery plates has been investigated. It is established that structural groups of the pyrocatechin type (Quebraco and EZE-Skitan) have effective expander action. Quebraco increases the plate capacity during the first cycles. EZE-Skitan increases the capacity of the plates after 50 to 60 charge/discharge cycles, when disintegration of its structure, probably to pyrocatechin groups, proceeds. By applying a new method for determining the expander stability, it is found that expanders containing pyrocatechin structural groups are more easily oxidized than hydrogenated. It is concluded that the most effective expander should be a combination of several compounds with different stabilities to oxidation and reduction. Appropriate expanders should be selected for each type of battery. (orig.)

  2. Effect of hydrogen and oxygen on stability of expanders and performance of lead/acid batteries

    Science.gov (United States)

    Pavlov, D.; Gancheva, S.; Andreev, P.

    1993-10-01

    Expanders are organic additives to the negative active mass that increase plate capacity, especially at low temperatures. They operate under constant hydrogen and oxygen attack at strongly negative potentials as a result of which they undergo degradation. This leads to changes in plate capacity, which may limit the life of the battery. The influence of Velex, Mimosa, Quebraco, Syntan NK (SNK), and EZE-Skitan on the electrochemical characteristics and the life of negative battery plates has been investigated. It is established that structural groups of the pyrocatechin type have effective expander action.

  3. Microphotokinesigraphic analysis of buffalo spermatozoa I. Characteristic features and significance of the immobile buffalo spermatozoa

    Directory of Open Access Journals (Sweden)

    M. Boichev

    2010-02-01

    Full Text Available The article discusses the results of a study of immobile spermatozoa of buffalo bulls from Bulgarian murrah breed, based on photo images registered in various displays in conditions of dark background photokinesis. The analysis showed the way developer affects the brightness of kinesigrams. The study is based on samples of semen of six buffalos analysed by means of the microphotokinetic method developed by Tchakarov and Natchev. Brightness parameters of the cells and their photokinetic images have been established photometrically; their metric parameters have been defined by means of an eyepiece and object micrometer. It has been found out that the optimal exposure time for a photokinetic analysis of buffalo spermatozoa was(is 5 sec, and the recommended developer for treating of negative registration material is the pyrocatechin developer by Windisch.

  4. Photophysical properties of catechol axially substituted tetra-α-(pentyloxy) titanium (IV) phthalocyanine

    Science.gov (United States)

    Yu, Xinxin; Lin, Ting; Lv, Huafei; Pan, Sujuan; Wu, Shijun; Zeng, Di; Jiang, Yufeng; Wang, Yuhua; Yang, Hongqin; Huang, Yide; Peng, Yiru

    2016-10-01

    Metal phthalocyanines (MPcs) have been found to be a promising photosensitizers for photodynamic therapy (PDT) of cancers and non-cancer diseases. Nevertheless, phthalocyanines are substantially limited in clinical applications owing to their poor solubility, aggregation and insufficient selectivity for cancer cells. Catechol is an important pharmaceutical intermediate, playing important in vivo biological activity in medicine. Using catechol (pyrocatechin) as axial ligands, utilizing of the pharmaceutical effect of catechins, could improve the bioavailability, and achieve synergistic therapeutic effect in PDT. To address these issues, a novel catechol axially substituted tetra-α-(pentyloxy) titanium(IV) (TiPc(OC5H11)4-Catechol) was synthesized. The structure of TiPc(OC5H11)4-Catechol was characterized by elemental analysis, IR, 1HNMR and MS methods. The photophysical properties of TiPc(OC5H11)4 and TiPc(OC5H11)4-Catechol have been studied by UV/Vis and steady-state fluorescence spectra. After being axially substituted with catechin groups, no obviously intensity and position of maximum wavelength in Q-band of TiPc(OC5H11)4 and TiPc(OC5H11)4-Catechol were observed. The fluorescence intensity of TiPc(OC5H11)4 was stronger than that of TiPc(OC5H11)4-Catechol, but the fluorescence lifetime of TiPc(OC5H11)4-Catechol was longer than that of TiPc(OC5H11)4. TiPc(OC5H11)4-Catechol may be considered as a promising photosensitizer for PDT.