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991.
《Analytical letters》2012,45(7):1265-1279
ABSTRACT Deproteinization of serum was performed by microwave irradiation combined with a small volume of diluted trichloracetic acid. The procedure reduced the protein level of the samples to less than 99% of the total with a small dilution factor (1+1) and allowed the determination of nickel and manganese by electrothermal atomic absorption spectrometry and copper and zinc by flame atomic absorption spectrometry directly without modifiers or matrix interferences. As metallic ions are normally bonded to serum proteins they must be released during protein precipitation. Spiked serum samples were submitted, before the deproteinization, to an incubation treatment to bond the added ions to the proteins. To check the efficiency of the incubation time for each ion, serum samples were ultrafiltered at set time intervals and the metals determined in the ultrafiltrate. The proposed method was compared with the common deproteinization by acids for the separation of the proteins. The reduction of proteins allowed a small dilution of the sample and the use of faster temperature programmes for the determination of nickel and manganese by electrothermal atomic absorption spectrometry and the aspiration of samples more similar to aqueous standards for copper and zinc determination by flame atomic absorption spectrometry. Recoveries from spiked, incubated and deproteinized samples compared to only diluted samples show that the method can satisfactorily be used for atomic absorption spectrometric determination of these elements. 相似文献
992.
A new tetranuclear manganese complex [Mn2IIMn2III(bhmcpH)2(hmp)4Cl2(MeOH)2] ( 1 ) [bhmcpH3 = 2, 6‐bis(hydroxymethyl)‐4‐chlorophenol, hmpH = 2‐(hydroxymethyl)pyridine] was synthesized and characterized. X‐ray diffraction analyses reveal that complex 1 crystallizes in the monoclinic space group P21/c. It has a mixed‐valence tetranuclear dicubane unit, which comprises two MnII and two MnIII ions. The temperature dependence of the magnetic susceptibilities of 1 indicates ferromagnetic interactions between the manganese ions. 相似文献
993.
994.
合成了Cu/Al原子比分别为2.0、3.1、4.1的CuAl类水滑石样品,焙烧得到CuAl复合氧化物。在Cu/Al原子比为3.1的CuAl氧化物表面浸渍碱金属盐溶液,制备改性CuAl复合氧化物,用AES、XRD、FT-IR、BET、H2-TPR、XPS等技术对催化剂进行了结构表征,考察了CuAl复合氧化物组成、碱金属助剂类型和K的前驱物对改性催化剂在有氧气氛中催化分解N2O活性的影响。结果表明,Na、K、Cs改性CuAl复合氧化物均提高了催化剂活性,但K助剂的增强效应最显著;钾的不同前驱物改性CuAl复合氧化物的催化活性有显著差异,加入碳酸钾、草酸钾提高了催化剂的活性,而加入醋酸钾、硝酸钾反而降低了催化剂活性。优化出的K改性CuAl复合氧化物催化剂在含氧含水气氛的N2O分解反应中表现出了较高的活性。 相似文献
995.
《Analytical letters》2012,45(11):1729-1749
Abstract Higher order derivative techniques are mainly used in deconvoluting the overlapping absorption spectra of various analytes in their determination. The procedure utilizing higher order derivatives in molecular absorption spectrophotometry essentially are based on the formation of binary complex viz. metal reacting with a chromogenic reagent. This paper reports a fourth order derivative spectrophotometric procedure for the determination of traces of cobalt based on the liquid-liquid extraction of ternary ion - asociation complex -cobalt, 1, 10-phenanthroline, rose bengal into chloroform. The developed procedure is simple, rapid, reliable and allows the determination of as low as 6 ppb of cobalt in high purity rare earth oxides and salts. 相似文献
996.
We report on the fabrication of a transparent photostable cell circuit composed of drive and resistor diodes which are face‐to‐face connected to each other with different device area. The diodes consisted of e‐beam evaporated p‐NiO on sputter‐deposited n‐ZnO for p/n diode formation on indium‐tin‐oxide glass. Our transparent diodes show photostable rectifying behavior, about 103 on/off current ratio and even dynamic rectification at a maximum frequency of 100 Hz AC input signal in ambient light. The noticeable photo‐responsivity of the circuit was obtained only under ultraviolet (UV) light. We conclude that our transparent diode circuit is promising in enriching the field of transparent device electronics. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
997.
Shengwen Wang 《Crystal Research and Technology》2008,43(8):894-898
To explore the possibility of obtaining the metal‐organic frameworks (MOFs) bearing the 2‐bromo‐1,4‐benzenedicarboxylate ligand, one new Mn(II) and one Co(II) coordination polymers, [Mn(HL)2(bipy)2·2H2O]·bipy ( 1 ) and [Co(L)(bpe)] ( 2 ) (bipy=4,4′‐bipyridine; bpe=1,2‐bis(4‐pyridyl)ethene) were synthesized and characterized by elemental analysis and X‐ray diffraction analysis. Compounds 1 exhibits one‐dimensional coordination chains, which are further connected to form two dimensional supramolecular networks through hydrogen bonding interactions. Compound 2 presents a two‐fold interpenetrating two‐dimensional layer structure. The 2‐bromo‐1,4‐benzenedicarboxylate anion exhibits different coordination modes in the two complexes. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
998.
Highly oriented thin films of cerium oxide with variable ratio of Ce3+/Ce4+ were grown on Ru(0 0 0 1) single crystal surface and loaded with a fixed, low coverage of Rh. The chemisorption of NO on the resulting model catalyst was studied by soft X-ray photoemission which yielded the relative quantities of N containing species on the surface as a function of temperature, and by thermal desorption which yielded the relative yields of NO and N2 desorbed. It is found that the ability of the reduced Rh clusters to dissociate NO depends upon the oxidation state of the ceria upon which it is deposited, and for highly reduced ceria surfaces effectively 100% of Rh-adsorbed NO dissociates by 350 K. Possible causes of this surprising behavior are discussed. 相似文献
999.
First-principles calculations based on density functional theory in the generalised gradient approximation, together with pseudopotentials and plane-wave basis sets, have been used to investigate the energetics of oxygen adsorption on stoichiometric and weakly and strongly reduced SnO2(1 1 0) surfaces. It is shown that, if the surface species formed by oxygen adsorption are restricted to be charge neutral, then oxygen cannot be exothermically adsorbed from the gas phase on the stoichiometric surface. A variety of molecular and dissociative modes of adsorption are examined on the reduced surface produced by removing all bridging oxygens and on the weakly reduced surface that results from removal of only a fraction of these oxygens, with the adsorbed species being in both the singlet and the triplet states, and we identify a number of modes not discussed before in the literature. We use the calculated adsorption energies to propose a tentative assignment of these adsorption modes to the peaks observed in temperature programmed desorption experiments on the SnO2 and TiO2(1 1 0) surfaces. 相似文献
1000.