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A two-dimensional steady-sate analysis of semi-infinite brittlecrack growth at a constant subcritical rate in an unboundedfully-coupled thermoelastic solid under mixed-mode thermomechanicalloading is made. The loading consists of normal and shear tractionsand heat fluxes applied as point sources (line loads in theout-of-plane direction). A related problem is solved exactly in an integral transformspace, and robust asymptotic forms used to reduce the originalproblem to a set of integral equations. The equations are partiallycoupled and exhibit operators of both Cauchy and Abel types,yet can be solved analytically. The temperature change field at a distance from the moving crackedge is then constructed, and its dominant term is found tobe controlled by the imposed heat fluxes. The role of this termis, indeed, enhanced if the heat fluxes serve to render thecrack as a net heat source/sink for the solid, as opposed tobeing a transmitter of heat across its plane. More generally,the influence of the thermoelastic coupling on this field, aswell as other functions, is found to increase with crack speed. 相似文献
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da Silva RS Marchesi MS Khin C Lunardi CN Bendhack LM Ford PC 《The journal of physical chemistry. B》2007,111(24):6962-6968
The photochemical behavior of the tetraazamacrocyclic complex trans-RuCl([15]ane)(NO)2+ (RuNO2+) in a 10 mM phosphate buffer solution, pH 7.4, and in the presence of Ru(NH3)5pz2+ (Rupz2+) is reported. Irradiation (436 nm) of an aqueous solution containing both cationic complexes as PF6- salts labilizes NO from RuNO2+ with a quantum yield (phiNO) dependent on the concentration of Rupz2+ with a maximum value of phiNO (1.03(11)x10(-3) einstein mol-1) found for a solution with equimolar concentrations (5x10(-5) M) of the two complexes in phosphate buffer solution. The quantitative behavior of this system suggests that the two cations undergo preassociation such that photoexcitation of the visible absorbing Rupz2+ is followed by electron or energy transfer to RuNO2+, which does not absorb appreciably at the excitation wavelength, and this leads to NO release from the reduced nitrosyl complex. Notably, the NO release was not seen in the absence of phosphate buffer; thus, it appears that phosphate ions mediate NO generation, perhaps by facilitating formation of a supramolecular complex between the two ruthenium cations. Reexamination of the cyclic voltammetry of Rupz2+ showed that the electrochemical behavior of this species is also affected by the presence of the phosphate buffer. 相似文献
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Renata Galvão de Lima Marilia Gama Sauaia Camila Ferezin Iuri Muniz Pepe Nádia Mamede José Lusiane M. Bendhack Zênis Novais da Rocha Roberto Santana da Silva 《Polyhedron》2007
The entrapped [Ru(terpy)(L)NO](PF6)3, where terpy = 2,2′:6′,2″-terpyridine and L = 2,2′-bipyridine (bpy) and 3,4-diiminebenzoic acid (NH · NHq) complexes into sol–gel processed polysiloxane and silicone matrices, shows NO release characteristics when submitted to light irradiation at 355 and 532 nm, as judged by NO measurement using a NO-sensor electrode. The pharmacological properties of doped matrix showed vasodilator characteristics by visible light irradiation, which is of great interest because the target delivery system can avoid the occurrence of side effects possibly by the aquo ruthenium species. All matrices obtained showed to be amorphous materials. The scanning electron micrographs of the matrices showed irregularly shaped particles, with a broad size of 1000 μm for both matrices and homogeneous distribution. 相似文献
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Amita Gupta Alexei Yu Ganin Parmanand Sharma Vikrant Agnihotri LM Belova KV Rao Mikhail E Kozlov AA Zakhidov RH Baughman 《Pramana》2002,58(5-6):1051-1059
We present studies of novel nanocomposites of BiNi impregnated into the structure of opals as well as inverse opals. Atomic force microscopy and high resolution elemental analyses show
a highly ordered structure and uniform distribution of the BiNi filler in the matrix. These BiNi-based nanocomposites are
found to exhibit distinct ferromagnetic-like ordering with transition temperature of about 675 K. As far as we know there
exists no report in literature on any BiNi compound which is magnetic. 相似文献
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Mario Sérgio Pereira Marchesi Simone Aparecida Cicillini Ana Carolina Lemos Prazias Lusiane M. Bendhack Alzir Azevedo Batista Roberto Santana da Silva 《Transition Metal Chemistry》2012,37(5):475-479
The nitrosyl ruthenium complex, trans-[RuCl([15]aneN4)NO](PF6)2, ([15]aneN4?=?1,4,8,12-tetraazacyclopentadecane), exhibits vasorelaxation characteristics attributed to its nitric oxide release properties. The observed in vitro and in vivo vasodilation is dependent on noradrenaline concentration. We report here the chemical mechanism of the reaction between noradrenaline and trans-[RuCl([15]aneN4)NO](PF6)2 in aqueous phosphate buffer solution at pH 7.40. NO measurement by NO-sensor electrode, cyclic voltammetry, 31PNMR and HPLC analysis were used to investigate the reduction process as the fundamental step for NO release characteristic of trans-[RuCl([15]aneN4)NO](PF6)2. A supramolecular species containing HPO4 2? as a bridging group between noradrenaline and trans-[RuCl([15]aneN4)NO](PF6)2 is suggested as an intermediate prior to the reduction of the nitrosyl ruthenium complex. 相似文献
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Meredith A. Crisalli Lilian P. Franco Bruno R. Silva Alda K. M. Holanda Lusiane M. Bendhack 《Journal of Coordination Chemistry》2018,71(11-13):1690-1703
AbstractThis research presents the synthesis and characterization of the photochemical nitric oxide (NO) precursor Ru(salenCO2H)(NO)Cl (1, salenCO2H = N,N’-ethylenebis(3,3’-bis-carboxylsalicylideneiminato). This water-soluble ruthenium nitrosyl releases NO upon photolysis with a quantum yield that is pH dependent owing to the nitrosyl to nitrite conversion of that axial ligand at higher pH. Also described are the water, oxygen, and thermal stability of 1 and the cytotoxicity and the vascular relaxivity properties of 1 in the dark and under photolysis. 相似文献
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da Rocha ZN Marchesi MS Molin JC Lunardi CN Miranda KM Bendhack LM Ford PC da Silva RS 《Dalton transactions (Cambridge, England : 2003)》2008,(32):4282-4287
The synthesis of [Ru(NO(2))L(bpy)(2)](+) (bpy = 2,2'-bipyridine and L = pyridine (py) and pyrazine (pz)) can be accomplished by addition of [Ru(NO)L(bpy)(2)](PF(6))(3) to aqueous solutions of physiological pH. The electrochemical processes of [Ru(NO(2))L(bpy)(2)](+) in aqueous solution were studied by cyclic voltammetry and differential pulse voltammetry. The anodic scan shows a peak around 1.00 V vs. Ag/AgCl attributed to the oxidation process centered on the metal ion. However, in the cathodic scan a second peak around -0.60 V vs. Ag/AgCl was observed and attributed to the reduction process centered on the nitrite ligand. The controlled reduction potential electrolysis at -0.80 V vs. Ag/AgCl shows NO release characteristics as judged by NO measurement with a NO-sensor. This assumption was confirmed by ESI/MS(+) and spectroelectrochemical experiment where cis-[Ru(bpy)(2)L(H(2)O)](2+) was obtained as a product of the reduction of cis-[Ru(II)(NO(2))L(bpy)(2)](+). The vasorelaxation observed in denuded aortic rings pre-contracted with 0.1 mumol L(-1) phenylephrine responded with relaxation in the presence of cis-[Ru(II)(NO(2))L(bpy)(2)](+). The potential of rat aorta cells to metabolize cis-[Ru(II)(NO(2))L(bpy)(2)](+) was also followed by confocal analysis. The obtained results suggest that NO release happens by reduction of cis-[Ru(II)(NO(2))L(bpy)(2)](+) inside the cell. The maximum vasorelaxation was achieved with 1 x 10(-5) mol L(-1) of cis-[Ru(II)(NO(2))L(bpy)(2)](+) complex. 相似文献
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Willem de Haan Yolande AL Pijnenburg Rob LM Strijers Yolande van der Made Wiesje M van der Flier Philip Scheltens Cornelis J Stam 《BMC neuroscience》2009,10(1):101-12
Background
Although a large body of knowledge about both brain structure and function has been gathered over the last decades, we still have a poor understanding of their exact relationship. Graph theory provides a method to study the relation between network structure and function, and its application to neuroscientific data is an emerging research field. We investigated topological changes in large-scale functional brain networks in patients with Alzheimer's disease (AD) and frontotemporal lobar degeneration (FTLD) by means of graph theoretical analysis of resting-state EEG recordings. EEGs of 20 patients with mild to moderate AD, 15 FTLD patients, and 23 non-demented individuals were recorded in an eyes-closed resting-state. The synchronization likelihood (SL), a measure of functional connectivity, was calculated for each sensor pair in 0.5–4 Hz, 4–8 Hz, 8–10 Hz, 10–13 Hz, 13–30 Hz and 30–45 Hz frequency bands. The resulting connectivity matrices were converted to unweighted graphs, whose structure was characterized with several measures: mean clustering coefficient (local connectivity), characteristic path length (global connectivity) and degree correlation (network 'assortativity'). All results were normalized for network size and compared with random control networks. 相似文献
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