排序方式: 共有42条查询结果,搜索用时 15 毫秒
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Allred RA Huefner SA Rudzka K Arif AM Berreau LM 《Dalton transactions (Cambridge, England : 2003)》2007,(3):351-357
Treatment of the ebnpa (N-2-(ethylthio)ethyl-N,N-bis((6-neopentylamino-2-pyridyl)methyl)amine) ligand with a molar equivalent amount of Cd(ClO(4))(2).5H(2)O in CH(3)CN followed by the addition of [Me(4)N]OH.5H(2)O yielded the cadmium hydroxide complex [(ebnpaCd)(2)(mu-OH)(2)](ClO(4))(2) (1). Complex 1 has a binuclear cation in the solid-state with secondary hydrogen-bonding and CH/pi interactions involving the ebnpa ligand. In acetonitrile, 1 forms a binuclear/mononuclear equilibrium mixture. The formation of a mononuclear species has been confirmed by conductance measurements of 1 at low concentrations. Variable temperature studies of the binuclear/mononuclear equilibrium provided the standard enthalpy and entropy associated with the formation of the monomer as DeltaH degrees = +31(2) kJ mol(-1) and DeltaS degrees = +108(8) J mol(-1) K(-1), respectively. Enhanced secondary hydrogen-bonding interactions involving the terminal Cd-OH moiety may help to stabilize the mononuclear complex. Treatment of 1 with CO(2) in acetonitrile results in the formation of a binuclear cadmium carbonate complex, [(ebnpaCd)(2)(mu-CO(3))](ClO(4))(2) (2). 相似文献
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The complete orthotropic elastic-stiffness matrix of unidirectional, Borsic-filament-reinforced aluminum composites was experimentally evaluated for three different volume fractions by ultrasonic velocity measurements on thin plates. Longitudinal- and shear-velocity measurements were made in appropriate symmetry directions by direct contact or liquid-immersion techniques. The elastic constants determined by this pulsed through-transmission method were in agreement with micromechanical theories based on the properties of the constituent materials. Agreement was also found between engineering constants determined by mechanical testing and those calculated from the ultrasonic data. Finally, measurement of the ultrasonic-wave velocity has also been shown to be a rapid nondestructive-test method for determining filament-volume fraction in a fabricated part. 相似文献
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Treatment of a dinuclear zinc hydroxide complex ([(bmnpaZn)(2)(mu-OH)(2)](ClO(4))(2) (1) or [(benpaZn)(2)(mu-OH)(2)](ClO(4))(2) (2)) with excess equivalents of an aryl alcohol derivative (p-HOC(6)H(4)X; X = NO(2), CHO, CN, COCH(3), Br, H, OCH(3)) yielded the nitrogen/sulfur-ligated zinc aryloxide complexes [(bmnpa)Zn(p-OC(6)H(4)NO(2))](ClO(4)) (3), [(benpa)Zn(p-OC(6)H(4)NO(2))](ClO(4)) (4), [(benpa)Zn(p-OC(6)H(4)CHO)](ClO(4)) (5), [(benpa)Zn(p-OC(6)H(4)CN)](ClO(4)) (6), [(benpa)Zn(p-OC(6)H(4)COCH(3))](ClO(4)) x 0.5H(2)O (7), [(benpa)Zn(p-OC(6)H(4)Br)](ClO(4)) (8), [(benpa)Zn(p-OC(6)H(5))](ClO(4)) (9), and [(benpa)Zn(p-OC(6)H(5)OCH(3))](ClO(4)) (10). The solid state structures of 2, 3, 5, and 6 have been determined by X-ray crystallography. While 3 and 6 exhibit a mononuclear zinc ion possessing a distorted five-coordinate trigonal bipyramidal geometry, in 5 each zinc center exhibits a distorted six-coordinate octahedral geometry resulting from coordination of the aldehyde carbonyl oxygen of another zinc-bound aryloxide ligand, yielding a chain-type structure. Zinc coordination of the aldehyde carbonyl of 5 is indicated by a large shift (>40 cm(-)(1)) to lower energy of the carbonyl stretching vibration (nu(C[double bond]O) in solid state FTIR spectra of the complex. In the solid state structures of 3, 5, and 6, a hydrogen-bonding interaction is found between N(3)-H of the supporting bmnpa/benpa ligand and the zinc-bound oxygen atom of the aryloxide ligand (N(3)...O(1) approximately 2.78 A). Solution (1)H and (13)C NMR spectra of 3-10 in CD(3)CN and FTIR spectra in CH(3)CN are consistent with all of the aryloxide complexes having a similar solution structure, with retention of the hydrogen-bonding interaction involving N(3)-H and the oxygen atom of the zinc-coordinated aryloxide ligand. For this family of zinc aryloxide complexes, a correlation was discovered between the chemical shift position of the N(3)-H proton resonance and the pK(a) of the parent aryl alcohol. This correlation indicates that the strength of the hydrogen-bonding interaction involving the zinc-bound aryloxide oxygen is increasing as the aryloxide moiety increases in basicity. 相似文献
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Presenda A Allred DB Baneyx F Schwartz DT Sarikaya M 《Colloids and surfaces. B, Biointerfaces》2007,57(2):256-261
Crystalline cell surface layer proteins (S-layers) can be used in electrochemical fabrication to create nanoscale arrays of metals and oxides on surfaces so long as the proteins maintain their long-range order during processing. We have explored the stability of the HPI layer protein (the S-layer protein from the microorganism Deinococcus radiodurans) adsorbed onto platinum surfaces after immersion in sulfuric acid or sodium hydroxide electrolytes ranging in pH from 0 to 14 over time periods ranging from 1 to 1000 s. Topographic data obtained by atomic force microscopy (AFM) was used to characterize the protein stability, judged by its retention of long-range order after immersion. The compiled data revealed that, under these solution conditions and in this environment, the HPI layer protein has a dose-dependent structural stability “envelope” in the acidic range from 1 < pH < 4. The protein retains its long-range order up to 1000 s from pH 4 to 11, and has a sharp stability edge between pH 12 and 13. Interestingly, the more stringent requirement of stability (i.e., retention of long-range order) defined in the context of electrochemical fabrication for this protein narrowed the window of stability in pH and time when compared to previous stability studies reported for this protein. 相似文献
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The EZ Gluten assay is a rapid immunochromatographic screening method for qualitative detection of gluten in raw and cooked foods and beverages and on environmental surfaces. This AOAC Performance Tested Method study evaluated the EZ Gluten assay as an effective method for the detection of gluten in four selected matrixes: rice flour, cooked dough, beer, and dog food. In addition, the method was evaluated for its effectiveness in detecting gluten contamination of > or =1 microg/2 in.2 (25 cm2) stainless steel surface area. The EZ Gluten demonstrated 100% specificity [probability of detection (POD) 0.00, confidence interval (CI) 0.00-0.01] and 99% sensitivity (POD 0.99, CI 0.97-0.995) at the 10 ppm level for all four matrixes, and 100% specificity (POD 0.00, CI 0.00-0.11) and sensitivity (POD 1.00, CI 0.886-1.00) at the 1 microg level on the stainless steel surface. Independent laboratory testing confirmed the internal validation results in one matrix and on the stainless steel surface. Lot-to-lot, stability, and robustness studies provided evidence that the EZ Gluten is a rugged, consistent method for the detection of gluten at levels as low as 10 ppm. 相似文献