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The content and the three dimensional distribution of impurities play an important role in the production process of high
purity rhenium powder (99.99% purity grade) and for its further use as alloying and coating agent in high temperature applications.
In this paper the characterization of raw Re granulate, Re powder, cleaned by heat treatment, Re coatings, produced by most
common preparation methods (PVD and VPS) and PM Re by means of SIMS is presented. The analysis of the three dimensional distribution
of trace elements is performed by 3D SIMS. The quantification of carbon, which was not possible with other analytical techniques
as a result of the high volatility of Re2O7 until now, has been carried out by SIMS depth profile analysis. It is discussed if internal standards, produced by introduction
of defined amounts of carbon soot to the Re powder lead to useful results. 相似文献
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Anaya M Kwak M Musser AJ Müllen K Herrmann A 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(43):12852-12859
This work describes the synthesis and characterization of a new family of DNA amphiphiles containing modified nucleobases. The hydrophobicity was imparted by the introduction of a dodec-1-yne chain at the 5-position of the uracil base, which allowed precise and simple tuning of the hydrophobic properties through solid-phase DNA synthesis. The micelles formed from these modified DNA sequences were characterized by atomic force microscopy, dynamic light scattering, and polyacrylamide gel electrophoresis. These experiments revealed the role of the quantity and location of the hydrophobic units in determining the morphology and stability of the micelles. The effects of hybridization on the physical characteristics of the DNA micelles were also studied; these results showed potential for the sequence-specific noncovalent functionalization of the self-assembled aggregates. 相似文献
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Abstract A method is described utilizing the tetrazolium salts neotetrazolium chloride (NTC), triphenyltetrazolium chloride (TTC), C,N-diphenyl-N'-4,5-dimethylthiazol-2-yltetrazolium bromide (MTT) and various substrates to elucidate damage to the mitochondrial electron transport chain of intact cells following in vitro photodynamic therapy (PDT). Using this methodology, a portion of the dark toxicity manifested by Photofrin II (PII) was found to occur prior to entry of electrons into the transport chain through Complex I, as evidenced by the fact that the inhibition of MTT reduction was reversible by the addition of malic acid to the culture media. A second site of dark toxicity was found to be Complex IV (cytochrome oxidase). After photoirradiation of the cells, Complex I was found to be affected since malic acid could no longer reverse the inhibition of MTT reduction but it could be reversed by the addition of succinic acid, whose electrons enter the transport chain at Complex II. A second and more sensitive site of photoirradiation damage was found to be Complex IV. A region near cytochrome C was also affected by photoirradiation but appreciably less so than noted for Complexes I and IV. A kinetic analysis of MTT and TTC reduction following photoirradiation indicated that MTT reduction was sustained at a normal rate for 1 h after which it slowed down and eventually plateaued. In contrast, TTC reduction was found to be inhibited almost immediately indicating Complex IV is extremely susceptible to photoirradiation damage. Compared to other assays of mitochondrial function requiring subcellular fractionation, the use of tetrazolium salts is simpler to perform and can be done using physiologically relevant conditions. 相似文献
35.
能带是决定固体特性的头等重要的因素。我们用光谱方法对单相YBa2Cu2Ox高T。超导体进行了研究,测量了样品的反射-吸收谱、Raman光谱和荧光光谱.其350和500nm吸收带以及390nm,560nm荧光峰来自晶格中Cu+发光中心,是跃迁过程1A1g(3d10)-1Eg和~3Eg(3d94s1)。其720nm和860nm荧光峰来自Cu2+发光中心,是由于自由离子光谱项2D在八面体晶场、正交晶系晶场中分裂为5个能级之间的跃迁。此外,还有一些光谱可能来自晶格中Cu3+发光中心,其481cm-1和551cm-1声子对说明了312cm-1处声子对与电子系统是强耦合。 相似文献
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Musser JR Bayes R Davydov YI Depommier P Doornbos J Faszer W Gagliardi CA Gaponenko A Gill DR Green P Gumplinger P Hasinoff MD Henderson RS Hu J Jamieson B Kitching P Koetke DD Krushinsky AA Lachin YY Macdonald JA MacDonald RP Marshall GM Mathie EL Miasoedov LV Mischke RE Nord PM Olchanski K Olin A Openshaw R Porcelli TA Poutissou JM Poutissou R Quraan MA Rodning NL Selivanov V Sheffer G Shin B Sobratee F Stanislaus TD Tacik R Torokhov VD Tribble RE Vasiliev MA Wright DH;TWIST Collaboration 《Physical review letters》2005,94(10):101805
The TWIST Collaboration has measured the Michel parameter rho in normal muon decay, mu(+)--> e(+)nu(e)nu (mu). In the standard model, rho = 3/4. Deviations from this value imply mixing of left- and right-handed muon and electron couplings. We find rho=0.750 80+/-0.000 32(stat) +/- 0.000 97(syst) +/- 0.000 23, where the last uncertainty represents the dependence of rho on the Michel parameter eta. This result sets new limits on the W(L)-W(R) mixing angle in left-right symmetric models. 相似文献