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991.
Schoonover JR Dattelbaum DM Malko A Klimov VI Meyer TJ Styers-Barnett DJ Gannon EZ Granger JC Aldridge WS Papanikolas JM 《The journal of physical chemistry. A》2005,109(11):2472-2475
The time scale for triplet-triplet energy transfer (EnT) between a Ru(II) chromophore and a ligand bound anthracene acceptor in [Ru(II)(dmb)2(bpy-an)]2+ (dmb = 4,4'-dimethyl-2,2-bipyridine; bpy-an = 4-(9-anthrylethylene), 4-methyl-2,2-bipyridine) has been measured using femtosecond transient absorption spectroscopy. The appearance of the anthracene excited state is monitored following photoexcitation to a metal-to-ligand charge transfer (MLCT) state via the pi pi* absorption of the triplet excited state of anthracene. Our time-resolved experiments show the presence of fast, sub-100 ps energy transfer to the anthracene occurring on two characteristic time scales of 23 and 72 ps. 相似文献
992.
Determination of para-aminobenzoic acid,a degradation product of procaine hydrochloride,by zero-crossing first-derivative spectrometry 总被引:1,自引:0,他引:1
A first derivative spectrometric method has been developed for the determination of the para-aminobenzoic acid (PABA), a related substance and degradation product of the local anesthetic procaine hydrochloride (PH). The wavelength selected for the determination of para-aminobenzoic acid in the presence of procaine was 290 nm. At this wavelength the calibration graphs relating the amplitude of the signals to the concentration of para-aminobenzoic acid were linear up to 10 mg L(-1). The detection limit of para-aminobenzoic acid was 0.70 mg L(-1). The method is simple and rapid and does not require preliminary treatment of the sample. The method was validated. 相似文献
993.
Composite membranes based on gellan and poly(N-vinylimidazole) were prepared by using the method of solvent evaporation. In acid medium ionic interactions are established and evidenced by measurements of FTIR spectroscopy. The properties of these membranes were investigated by using elemental analysis, thermogravimetric analysis, atomic force microscopy and dynamic swelling experiments. The thermic behavior of the membranes depends on the nature of interactions and swelling degree is highly dependent on pH and composition. The properties of these membranes suggest potential applications in the field of biodegradable materials or as supports for drugs in view of their controlled release. 相似文献
994.
Haim Hacham Nurit Tetro Salit Kochavi-Azolai Nava Stern Dana Mizrahi Anna Lisenker Emanuel Gazit 《Accreditation and quality assurance》2007,12(8):409-413
The Department of Public Health Laboratories consists of five major laboratories located across the country of Israel: four
environmental laboratories performing microbiological and chemical testing of food and water products [accredited according
to International Organization for Standardization (ISO) 17025 since 1999) and a fifth laboratory that is dedicated to virology
testing (certified according to ISO 9000 since 2003). Historically, each laboratory operated independently and developed its
own quality assurance (QA). On November 2004, an important strategic decision was made: to unify all five laboratories’ QA
systems conformed to ISO 17025, ISO 15189, and ISO 9000—a transition from five laboratories operating independently in the
field of QA toward establishing a multisite laboratory. This process was considered and visualized as a major organizational
change and therefore raised some resistance among both QA managers and the professional laboratories’ management. Thus, it
was necessary to overcome the resistance and at the same time induce thoughts of ways of reshaping and formatting the new
and uniform quality manual and uniform standard operating procedures (SOPs). In September 2005, the first phase of the process
was completed, and all four environmental public health laboratories successfully passed a reaccreditation audit using a uniform
QA manual guide and partially uniform SOPs. We shall share our experience and discuss the major contributions of this process
to overall laboratory management.
Presented at the 3rd International Conference on Metrology, November 2006, Tel Aviv, Israel. 相似文献
995.
P. F. Vlad D. P. Popa E. C. Gorincioi M. N. Coltsa G. N. Mironov 《Russian Chemical Bulletin》1990,49(1):98-101
A synthetic route to 11-hydroxydrim-8(9)-en-7-one and 11,12-hydroxydrim-8(9)-en-7-one, valuable key intermediates for the
preparation of naturally occurring biologically active drimanic sesquiterpenoids, starting from easily available drim-8(9)-en-7-one
was developed. 11-Hydroxydrim-8(9)-en-7-one was obtained by peracidic oxidation of the enol acetate of drim-8(9)-en-7-one.
11,12-Dihydroxydrim-8(9)-en-7-one was synthesized from drim-8(9)-en-7-one by two routes, namely, by a five-step procedurevia 11-hydroxydrim-8(9)-en-7-one and by bromination of drim-8(9)-en-7-one with NBS to give 11,12-dibromodrim-8(9)-en-7-one followed
by its acetoxylation and deacetylation.
Deceased
Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 95–98, January, 2000. 相似文献
996.
Summary Two new diterpenoids have been isolated fromMarrubium peregrinum L.: a bicyclic diol C20H36O2, peregrinol — and a hydroxyketolactone C20H25O5, peregrinin. A substance C19H18O6 has been obtained as a by-product.Khimiya Prirodnykh Soedinenii, Vol. 2, No. 4, pp. 249–251, 1966 相似文献
997.
Mitochondrial and endoplasmic reticulum stress-induced apoptotic pathways are activated by 5-aminolevulinic acid-based photodynamic therapy in HL60 leukemia cells 总被引:17,自引:0,他引:17
Grebenová D Kuzelová K Smetana K Pluskalová M Cajthamlová H Marinov I Fuchs O Soucek J Jarolím P Hrkal Z 《Journal of photochemistry and photobiology. B, Biology》2003,69(2):71-85
We studied the mechanism of the cytotoxic effects of 5-aminolevulinic acid-based photodynamic therapy (ALA-PDT; induction with 1 mM ALA for 4 h followed by a blue light dose of 18 J/cm(2)) on the human promyelocytic leukemia cell line HL60 using biochemical and electron microscopy methods. The disruption of mitochondrial membrane potential, deltapsi(m), was paralleled by a decrease in ATP level, unmasking of the mitochondrial antigen 7A6, release of cytochrome c into the cytoplasm, activation of caspases 9 and 3 and cleavage of poly(ADP-ribose) polymerase (PARP). This was followed by DNA fragmentation. These data suggest that ALA-PDT activates the mitochondrial apoptotic pathway. The level of endoplasmic reticulum Ca(2+)-binding chaperones ERp57 and ERp72 and of anti-apoptotic proteins Bcl-2 and Bcl-x(L) was decreased whereas that of Ca(2+)-binding protein calmodulin and the stress protein HSP60 was elevated following ALA-PDT. Inhibition of the initiator caspase 9, execution caspase 3 and Ca(2+)-dependent protease m-calpain, did not prevent DNA fragmentation. We conclude that, in our in vitro model, ALA-based photodynamic treatment initiates several signaling processes in HL60 cells that lead to rapidly progressing apoptosis, which is followed by slow necrosis. Two apoptotic processes proceed in parallel, one representing the mitochondrial pathway, the other involving disruption of calcium homeostasis and activation of the endoplasmic reticulum stress-mediated pathway. 相似文献
998.
Anion binding has been achieved with a resorcinarene substituted with four 2,2'-dipicolylamine moieties on the upper rim. The four dipicolylamine groups reside in proximity on one rim of the cavitand. The dipicolylamine groups were protonated with triflic acid to provide the cationic ammonium sites for anion binding. This anion receptor binds strongly to anions of different geometries, such as H(2)PO(4)(-), Cl(-), F(-), CH(3)CO(2)(-), HSO(4)(-), and NO(3)(-). The association constants for binding these anions are large, on the order of log K = 5 in CD(3)CN, a solvent of intermediate dielectric constant. These values represent significant binding compared to other cavitands with nitrogen pendant groups. Evidence suggests that the cavitand provides two identical receptor sites formed by two dipicolylamine groups, facilitating the simultaneous binding of two anions. Intramolecular binding of anions between two protonated dipicolylamine groups is indicated on the basis of the comparison to a structurally similar monomeric analogue and by semiempirical PM3 molecular modeling. Titrations with the analogue result in much weaker anion association, even at high concentrations, indicating the importance of proximity and preorganization of sites on the cavitand upper rim. 相似文献
999.
It is shown that on the superacid cyclization of esters of bishomobicyclogeranylgeranic and E,E-bishomofarnesic acids fully cyclized hydroxyesters are formed in good yield, while on the interaction of esters of 6-hydroxy- and 6-acyloxy-15-bishomobicyclogeranylgeranic acids with a superacid no carbocyclization takes place.Institute of Chemistry, Moldovian Academy of Sciences, Kishinev. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 645–653, November–December, 1992. 相似文献
1000.
Badea Michaela Emandi Ana Marinescu Dana Cristurean Elena Olar Rodica Braileanu Ana Budrugeac P. Segal E. 《Journal of Thermal Analysis and Calorimetry》2003,72(2):525-531
this paper deals with the first investigation concerning the thermal stability of two 1-(2-benzothiazolyl)-3-methyl-4-azo-pyrazil-5-one
derivatives and their Cu(II) coordination compounds of type ((C4H9)4N)2[Cu(L)2]. The thermal decomposition steps were established.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献