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排序方式: 共有315条查询结果,搜索用时 15 毫秒
1.
M.G. Pujar N. Parvathavarthini Sidhartha S. Jena B.V.R. Tata R.K. Dayal H.S. Khatak 《Journal of Materials Engineering and Performance》2008,17(6):793-801
In the present work 316LN as well as 316 stainless steel (SS) coupons each of dimensions (0.025 × 0.018 × 0.006 m3) in well-polished condition were used as two nominal electrodes which were immersed in the aerated solution of 0.5 M NaCl.
Correlated current and potential electrochemical noise (EN) signals were collected at 1 Hz sampling frequency for 1 h daily
over a period of 30 days. The detrended EN data were used to calculate the noise resistance (R
N) as well as the spectral noise resistance at zero frequency (R
SNo) values and other statistical parameters. To study the nature of pits and distribution of their diameters as well as depths,
extensive observations of the pitted and the blank specimens were carried out using Confocal Laser Scanning Microscopy (CLSM).
The current and the potential records of the two alloys showed distinct differences in their corrosion behavior. It was observed
that within less than 4 h of immersion, 316SS showed signals indicative of unstable pitting and onset of stable pitting was
noticed after 48 h of exposure. However, until about 24 h, 316LN showed just the random signals and unstable pitting was observed
after 28 h. The signals clearly indicated continuous growth of the stable pits in 316SS as against the repassivation of the
unstable pits in 316LN after 7 days exposure. It was observed that R
N values showed a continuous decrease in the case of 316SS, but were quite stable in the case of 316LN over the exposure period.
Concurrent to these observations it was observed that 316SS specimen was extensively pitted. The frequency distributions of
pit diameters as well pit depths were observed to be highest at 10-20 μm and 5-10 μm, respectively. However, pits with as
large as 70-80 μm diameter and as deep as 20-25 μm too were observed. No pits were observed in case of 316LN even after 30 days
of exposure, an observation that corroborates well with the stable R
N values. Thus, in the present investigation, the long-term tests using EN technique coupled with CLSM studies conclusively
prove that many unstable pits initiated in 316SS turn into stable ones resulting in insidious localized corrosion attack whereas
the unstable pits initiated in 316LN get passivated in the simulated coastal environment. 相似文献
2.
Hrudananda Jena K. V. Govindan Kutty T. R. N. Kutty 《Journal of Alloys and Compounds》2003,350(1-2):102-112
Structural transformation and ionic transport properties are investigated on wet-chemically synthesized La1−xMnO3 (x=0.0–0.18) compositions. Powders annealed in oxygen/air at 1000–1080 K exhibit cubic symmetry and transform to rhombohedral on annealing at 1173–1573 K in air/oxygen. Annealing above 1773 K in air or in argon/helium at 1473 K stabilized distorted rhombohedral or orthorhombic symmetry. Structural transformations are confirmed from XRD and TEM studies. The total conductivity of sintered disks, measured by four-probe technique, ranges from 5 S cm−1 at 298 K to 105 S cm−1 at 1273 K. The ionic conductivity measured by blocking electrode technique ranges from 1.0×10−6 S cm−1 at 700 K to 2.0×10−3 S cm−1 at 1273 K. The ionic transference number of these compositions ranges from 3.0×10−5 to 5.0×10−5 at 1273 K. The activation energy deduced from experimental data for ionic conduction and ionic migration is 1.03–1.10 and 0.80–1.00 eV, respectively. The activation energy of formation, association and migration of vacancies ranges from 1.07 to 1.44 eV. 相似文献
3.
4.
Secretion is one of the most fundamental cellular processes. Porosomes have been demonstrated as the universal secretory machinery in cells. Earlier studies determine the presence of a number of proteins in porosomes, among them the N- and P/Q-type calcium channels, actin, syntaxin-1, synaptotagmin-1, vimentin, the N-ethylmaleimide-sensitive factor (NSF), the chloride channel CLC-3, and the alpha subunit of the heterotrimeric GTP-binding protein G(o). Studies demonstrate that t-SNAREs localize at the base of porosomes, and directly interact with calcium channels. In the present study, we demonstrate that Syntaxin-1 co-localizes with cholesterol in solubilized synaptosomal membrane preparations. Depletion of cholesterol, results in the dissociation of both Syntaxin-1 and N-type calcium channel from neuronal porosomes. Thus, cholesterol participates as an integral component of the neuronal porosome complex, and is required for its stability. 相似文献
5.
Novel wet-chemical methods of synthesis have been adopted to synthesize nano-crystalline CeO2 and Gd-substituted compositions aiming to explore an efficient oxide ion conducting solid electrolyte for intermediate temperature solid oxide fuel cell (IT-SOFC) applications. Nano-crystalline CeO2 powders were synthesized by combustion method using redox mixture of cerric ammonium nitrate or cerium nitrate and maleic acid or 1,3-dimethylurea and compared with high surface area CeO2 powders prepared by hydrothermal technique with microwave precipitated precursor from aqueous solutions of (NH4)2Ce(NO3)6 and urea. The grain size achieved by the hydrothermal technique is ∼7 nm which is smaller than that of commercial nano CeO2 powders. Conventional or microwave sintering was used to prepare dense Ce0.8Gd0.2O1.9 pellets from the ceria powders made of redox mixture of cerium nitrate, 1,3-dimethylurea (DMU) and Gd2O3 as the starting ingredients. The samples were characterized by X-ray diffractometry (XRD), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), and ac impedance spectroscopy. The ionic conductivity measured for the pellet sintered at 1400 °C is 1 × 10−2 and 2.4 × 10−2 S/cm at 700 °C and 800 °C respectively. 相似文献
6.
This paper addresses the effectiveness of soft computing approaches such as evolutionary computation (EC) and neural network (NN) to system identification of nonlinear systems. In this work, two evolutionary computing approaches namely differential evolution (DE) and opposition based differential evolution (ODE) combined with Levenberg Marquardt algorithm have been considered for training the feed-forward neural network applied for nonlinear system identification. Results obtained envisage that the proposed combined opposition based differential evolution neural network (ODE-NN) approach to identification of nonlinear system exhibits better model identification accuracy compared to differential evolution neural network (DE-NN) approach. The above method is finally tested on a one degree of freedom (1DOF) highly nonlinear twin rotor multi-input–multi-output system (TRMS) to verify the identification performance. 相似文献
7.
Chinmay Vijay Tikhe Victor Cardoso-Jaime Shengzhang Dong Natalie Rutkowski George Dimopoulos 《International journal of molecular sciences》2022,23(14)
Cysteine-rich trypsin inhibitor-like domain (TIL)-harboring proteins are broadly distributed in nature but remain understudied in vector mosquitoes. Here we have explored the biology of a TIL domain-containing protein of the arbovirus vector Aedes aegypti, cysteine-rich venom protein 379 (CRVP379). CRVP379 was previously shown to be essential for dengue virus infection in Ae. aegypti mosquitoes. Gene expression analysis showed CRVP379 to be highly expressed in pupal stages, male testes, and female ovaries. CRVP379 expression is also increased in the ovaries at 48 h post-blood feeding. We used CRISPR-Cas9 genome editing to generate two mutant lines of CRVP379 with mutations inside or outside the TIL domain. Female mosquitoes from both mutant lines showed severe defects in their reproductive capability; mutant females also showed differences in their follicular cell morphology. However, the CRVP379 line with a mutation outside the TIL domain did not affect male reproductive performance, suggesting that some CRVP379 residues may have sexually dimorphic functions. In contrast to previous reports, we did not observe a noticeable difference in dengue virus infection between the wild-type and any of the mutant lines. The importance of CRVP379 in Ae. aegypti reproductive biology makes it an interesting candidate for the development of Ae. aegypti population control methods. 相似文献
8.
Chinmay Rao Asok Ray Soumik Sarkar Murat Yasar 《Signal, Image and Video Processing》2009,3(2):101-114
Symbolic dynamic filtering (SDF) has been recently reported in literature as a pattern recognition tool for early detection
of anomalies (i.e., deviations from the nominal behavior) in complex dynamical systems. This paper presents a review of SDF
and its performance evaluation relative to other classes of pattern recognition tools, such as Bayesian Filters and Artificial
Neural Networks, from the perspectives of: (i) anomaly detection capability, (ii) decision making for failure mitigation and
(iii) computational efficiency. The evaluation is based on analysis of time series data generated from a nonlinear active
electronic system.
This work has been supported in part by the U.S. Army Research Laboratory and the U.S. Army Research Office under Grant No.
W911NF-07-1-0376, by the U.S. Office of Naval Research under Grant No. N00014-08-1-380, and by NASA under Cooperative Agreement
No. NNX07AK49A. 相似文献
9.
Kishore K Jena Tapan K Rout Ramanuj Narayan Kothapalli V S N Raju 《Polymer International》2012,61(7):1101-1106
(Hyperbranched polyurethane‐urea)/[(3‐aminopropyl)triethoxysilane]‐ZnO (HBPUU‐APTES‐ZnO) hybrid coatings were synthesized using an inexpensive mixing technique by varying the APTES‐modified ZnO concentration. The mechanical and surface properties of the hybrid coating films were studied and compared with unmodified and modified ZnO. The corrosion, solvent and abrasion resistance show significant enhancement in HBPUU‐APTES‐ZnO hybrids and their properties are increased with increasing APTES‐ZnO concentration. This hybrid coating has opened up an opportunity for automotive topcoat application. Copyright © 2012 Society of Chemical Industry 相似文献
10.
Hybrid coatings of hyperbranched polyurethane‐urea (HBPUU) containing ZnO nanoparticles were prepared by mixing the hyperbranched polyurethane with the nanoparticles. The films were stored at room temperature and laboratory humidity conditions for one week to yield completely cured hybrid films. The ZnO nanoparticles were found to be well dispersed in the polymer up to 3 wt%. The structure–property relationship of various HBPUU–ZnO hybrid coatings was analysed using a Fourier transform infrared peak deconvolution technique with a Gaussian curve‐fitting procedure, while their viscoelastic, thermomechanical and surface morphology were studied using X‐ray diffraction, dynamic mechanical thermal analysis, thermogravimetric analysis, a universal testing machine, scanning electron microscopy, atomic force microscopy and contact angle instruments. The thermal stability and mechanical properties of the hybrid composite films improved with increasing ZnO content, which was believed to be due to thermal insulation in the presence of nanoparticles. Water contact angle data suggested that the hydrophobic character of the hybrid composites increased with increasing nanoparticle concentration. The antimicrobial property of the HBPUU–ZnO hybrid coatings was studied using the disc diffusion method. HBPUU–ZnO hybrid coatings showed good antimicrobial properties compared to HBPUU. Copyright © 2012 Society of Chemical Industry 相似文献