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81.
Japaridze NJ Okuneva VG Qsovreli MG Surmava AG Lordkipanidze TG Kiladze MT Zhvania MG 《Micron (Oxford, England : 1993)》2012,43(9):948-953
Porosomes are the universal secretory machinery in cells, where membrane-bound secretory vesicles transiently dock and fuse to release intravesicular contents to the outside of the cell during cell secretion. Studies using atomic force microscopy, electron microscopy, electron density and 3D contour mapping, provided rich nanoscale information on the structure and assembly of proteins within the neuronal porosome complex in normal brain. However it remains uncertain whether pathological conditions that alter process of neurotransmission, provoke alterations in the porosome structure also. To determine if porosomes are altered in disease states, the current study was undertaken for first time using high resolution electron microscope. One of pathologies that produce subtle alteration at the presynaptic terminals has been demonstrated to be hypokinetic stress. The central nucleus of amygdale is the brain region, where such alterations are mostly expressed. We have examined the width and depth of the neuronal porosome complex and their alterations provoked by chronic hypokinetic stress in above mentioned limbic region. Specifically, we have demonstrated that despite alterations in the presynaptic terminals and synaptic transmission provoked by this pathological condition in this region, the final step/structure in neurosecretion--the porosome--remains unaffected: the morphometric analysis of the depth and diameter of this cup-shaped structure at the presynaptic membrane point out to the heterogeneity of porosome dimensions, but with unchanged fluctuation in norm and pathology. 相似文献
82.
Botequim D Maia J Lino MM Lopes LM Simões PN Ilharco LM Ferreira L 《Langmuir : the ACS journal of surfaces and colloids》2012,28(20):7646-7656
Here, we present new antimicrobial nanoparticles based on silica nanoparticles (SNPs) coated with a quaternary ammonium cationic surfactant, didodecyldimethylammonium bromide (DDAB). Depending on the initial concentration of DDAB, SNPs immobilize between 45 and 275 μg of DDAB per milligram of nanoparticle. For high concentrations of DDAB adsorbed to SNP, a bilayer is formed as confirmed by zeta potential measurements, thermogravimetry, and diffuse reflectance infrared Fourier transform (DRIFT) analyses. Interestingly, these nanoparticles have lower minimal inhibitory concentrations (MIC) against bacteria and fungi than soluble surfactant. The electrostatic interaction of the DDAB with the SNP is strong, since no measurable loss of antimicrobial activity was observed after suspension in aqueous solution for 60 days. We further show that the antimicrobial activity of the nanoparticle does not require the leaching of the surfactant from the surface of the NPs. The SNPs may be immobilized onto surfaces with different chemistry while maintaining their antimicrobial activity, in this case extended to a virucidal activity. The versatility, relative facility in preparation, low cost, and large antimicrobial activity of our platform makes it attractive as a coating for large surfaces. 相似文献
83.
Imidazolium-based ionic liquids (ILs) containing ester moieties in the side chain were successfully used as an alternative to traditional ILs in the Beckmann rearrangement of ketoximes catalyzed by 2,4,6-trichloro[1,3,5]triazine. The procedure is mild and suitable for both aromatic and cycloaliphatic substrates affording the rearrangement products in good to quantitative yields. The process is eco-sustainable since these ILs are biodegradable and in addition they can be recovered and reused. 相似文献
84.
Tatiana F. Pereira Marcelo F. Oliveira Izaque A. Maia Jorge V. L. Silva Marysilvia F. Costa Rossana M. S. M. Thiré 《Macromolecular Symposia》2012,319(1):64-73
Summary: Poly(3-hydroxybutyrate) (PHB) 3D porous cubes were successfully built with Selective Laser Sintering (SLS), one of the many existing 3D printing technologies. The resulting cubes presented shape and dimensions very close to the corresponding virtual model. Moreover, they were resistant to handling without presenting any visible damage. The PHB powder did not present variation in thermal properties and chemical composition after 32.15 hours of SLS process as observed by proton nuclear resonance (1H NMR) and differential scanning calorimetry (DSC) analysis, indicating that it can be re-utilized to print additional structures without affecting the reproducibility of the process. 相似文献
85.
Maia M. Svanadze 《PAMM》2012,12(1):283-284
In this paper the linear theory of viscoelasticity for Kelvin-Voigt materials with voids is considered. The uniqueness and existence theorems for internal boundary value problem (BVP) of steady vibrations are proved by means of the potential method (boundary integral method) and the theory of singular integral equations. The application of this method to the 3D BVP of the considered theory reduces this problem to 2D singular integral equation. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
86.
We present an axiomatic framework for what we call Mach's mechanics, inspired on the ideas by A. K. T. Assis and P. Graneau about relational mechanics. We show that, in contrast to a suggestion of these authors, Mach's principle does not need to be committed with any Weber's like gravitational force. Actually it is possible to settle an axiomatic framework for non-relativistic classical particle mechanics which incorporates Mach's principle and is still consistent with any force that obeys the Newtonian action-reaction principle. We make further criticisms concerning relational mechanics. 相似文献
87.
本文报导了采用氩离子激光器来泵浦Pr3+:YLF晶体,应用声光调制器实现了主动锁模;同时应用振动─高反射平面镜也实现了被动锁模,两种锁模均得到了ps光脉冲.据作者了解这是这种晶体材料的第一次锁模运转. 相似文献
88.
We present a general method for the linear least-squares solutionof overdetermined and underdetermined systems. The method isparticularly efficient when the coefficient matrix is quasi-square,that is when the number of rows and number of columns is almostthe same. The numerical methods for linear least-squares problemsand minimum-norm solutions do not generally take account ofthis special characteristic. The proposed method is based onLU factorization of the original quasi-square matrix A, assumingthat A has full rank. In the overdetermined case, the LU factorsare used to compute a basis for the null space of AT. The right-handside vector b is then projected onto this subspace and the least-squaressolution is obtained from the solution of this reduced problem.In the case of underdetermined systems, the desired solutionis again obtained through the solution of a reduced system.The use of this method may lead to important savings in computationaltime for both dense and sparse matrices. It is also shown inthe paper that, even in cases where the matrices are quite small,sparse solvers perform better than dense solvers. Some practicalexamples that illustrate the use of the method are included. 相似文献
89.
It is shown that the Einstein and Yang-Mills equations arise from the conditions for the space-time to be a submanifold of
a pseudo-Euclidean space with dimension greater than 5. Some possible applications to cosmology, spin-2 fields, and geometrodynamics
are discussed. 相似文献
90.
Neves Pérson P. Maia Lauro J.Q. Bernardi Maria I.B. Zanatta Antônio R. Mastelaro Valmor R. Zanetti Sônia M. Leite Edson R. 《Journal of Sol-Gel Science and Technology》2004,29(2):89-96
A modified polymeric precursor method based on the Pechini process was used to synthesize -BaB2O4 (-BBO) crystalline phase. D-sorbitol (C6H14O6) was used as a polymerizing agent to avoid the loss of boron during the samples' calcination and crystallization. The -BBO stoichiometric crystalline phase was only obtained when sorbitol was added to the solution. The results of Raman spectroscopy show that the amorphous phase is only completely eliminated when the samples are heat-treated at 750°C for 20 h. Thin films of -BBO phase displaying a preferred orientation were obtained when crystallized at 750°C for 2 h and deposited on sapphire substrate. 相似文献