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排序方式: 共有2486条查询结果,搜索用时 78 毫秒
111.
Jignasu P. Mehta Digvijaysinh K. Parmar Haresh D. Nakum Dinesh R. Godhani Nisheeth C. Desai 《Journal of Porous Materials》2016,23(6):1507-1518
Zeolite-Y enslaved complexes were prepared by the Flexible ligand method. Synthesized materials were characterized by various spectral tools like powder X-ray diffraction, spectral studies (UV–Vis and FT-IR), chemical analysis (ICP-OES and elemental), scanning electron microscopy, AAS and 1H-NMR techniques. Further, BET and thermogravimetric (TG) analysis were also done for characterization of surface area, pore volume, thermal behavior, and related parameters. Baeyer–Villiger oxidation of cyclohexanone was carried out over Zeolite-Y enslaved complexes using hydrogen peroxide (H2O2) as an oxidant. The performance of the heterogeneous system with the homogeneous system was compared to determine the protection effect of the zeolitic matrix over the active center on the catalytic properties. In addition, the effect of experimental variables (various solvents, amount of catalyst, the mole ratio of substrate and oxidant, temperature, and reaction time) was examined in order to get absolute reaction conditions. Under the optimized reaction conditions, [Fe(nbab)2]-Y was found to be a potential candidate, achieving 70 % ?-caprolactone selectivity. 相似文献
112.
Multimedia Tools and Applications - Enforcing security and privacy guarantees for biometric users via protecting their unique and personalized attributes is an important area of research. There are... 相似文献
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114.
Chandrakantsing V. Pardeshi Veena S. Belgamwar Avinash R. Tekade Sanjay J. Surana 《Journal of materials science. Materials in medicine》2013,24(9):2101-2115
Here we report fabrication and evaluation of novel surface modified polymer–lipid hybrid nanoparticles (PLN) as robust carriers for intranasal delivery of ropinirole hydrochloride (ROPI HCl). Sustained release, avoidance of hepatic first pass metabolism, and improved therapeutic efficacy are the major objectives of this experiment. PLN were fabricated by emulsification-solvent diffusion technique and evaluated for physicochemical parameters, in vitro mucoadhesion, in vitro diffusion, ex vivo permeation, mucosal toxicity and stability studies. Box-Behnken experimental design approach has been employed to assess the influence of two independent variables, viz. surfactant (Pluronic F-68) and charge modifier (stearylamine) concentration on particle size, ζ-potential and entrapment efficiency of prepared PLN. Numerical optimization techniques were used for selecting optimized formulation sample, further confirmed by three dimensional response surface plots and regression equations. Results of ANOVA demonstrated the significance of suggested models. DSC and SEM analysis revealed the encapsulation of amorphous form of drug into PLN system, and spherical shape. PLN formulation had shown good retention with no severe signs of damage on integrity of nasal mucosa. Release pattern of drug-loaded sample was best fitted to zero order kinetic model with non-Fickian super case II diffusion mechanism. In vivo pharmacodynamic studies were executed to compare therapeutic efficacy of prepared nasal PLN formulation against marketed oral formulation of same drug. In summary, the PLN could be potentially used as safe and stable carrier for intranasal delivery of ROPI HCl, especially in treatment of Parkinson’s disease. 相似文献
115.
Sanjay Sampath 《Journal of Thermal Spray Technology》2010,19(5):921-949
Thermal spray has enjoyed unprecedented growth and has emerged as an innovative and multifaceted deposition technology. Thermal
spray coatings are crucial to the enhanced utilization of various engineering systems. Industries, in recognition of thermal
spray’s versatility and economics, have introduced it into manufacturing environments. The majority of modern thermal spray
applications are “passive” protective coatings, and they rarely perform an electronic function. The ability to consolidate
dissimilar material multilayers without substrate thermal loading has long been considered a virtue for thick-film electronics.
However, the complexity of understanding/controlling materials functions especially those resulting from rapid solidification
and layered assemblage has stymied expansion into electronics. That situation is changing: enhancements in process/material
science are allowing reconsideration for novel electronic/sensor devices. This review critically examines past efforts in
terms of materials functionality from a device perspective, along with ongoing/future concepts addressing the aforementioned
deficiencies. The analysis points to intriguing future possibilities for thermal spray technology in the world of thick-film
sensors. 相似文献
116.
Ayman Abdellatief Bruce A. Welt Jason Butler Eric McLamore Arthur A. Teixeira Sanjay Shukla 《Packaging Technology and Science》2014,27(8):651-662
A model was developed to simulate oxygen accumulation in space and time within cylindrical dynamic accumulation chambers that are used to measure oxygen transmission rate (OTR) of materials. The model is based on Fick's law of diffusion and was validated against actual OTR measurements of polymer film samples. Measured OTR values and thicknesses were inputted into the model and oxygen concentrations outputted by the model. OTRs determined from the output of the model was in close agreement to within 0.3–3% of the measured OTR. Oxygen concentration versus time curves generated from model output oxygen concentrations and experimentally measured oxygen concentrations for three actual films were also in agreement. The model was then used to simulate results from three hypothetical test films at varying chamber lengths in order to evaluate effects of accumulation chamber dimensions relative to films on resulting OTR measurements. A typical design scenario was used, where the oxygen sensor is mounted on the chamber wall opposite the sample film. Results demonstrate that dynamic accumulation OTR instrument designers have considerable flexibility in choosing accumulation chamber dimensions because deviations in OTR are only expected to occur at impractically extreme chamber lengths (>10 m) for the entire envelope of OTRs expected for typical packaging films. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
117.
Mechanical Properties Anisotropy of Cold-Rolled and Solution-Annealed Ni-Based Hastelloy C-276 Alloy
K. K. Mehta Prantik Mukhopadhyay R. K. Mandal A. K. Singh 《Metallurgical and Materials Transactions A》2014,45(8):3493-3504
This work describes a correlation among texture, in-plane anisotropy in tensile properties, and yield locus in Ni-based Hastelloy C-276 alloy. The alloy exhibits moderate values of in-plane anisotropy and anisotropy index, which has been attributed to the presence of moderate overall intensity of texture. The alloy displays two slopes in true plastic stress–strain curve and follows a Ludwigson relation. At low plastic strains, the sample displays the presence of annealing twins and less strain localization at grain boundaries, while the formation of deformation twins and high strain localization within the deformation twins and at the grain boundaries are observed in a high-strained region. The 45-deg and 67.5-deg orientation samples show relatively low ductility and low work-hardening exponent. This has been explained based on dislocation storage capacity and dynamic recovery coefficient using Kock–Mecking–Estrin analysis. 相似文献
118.
Srivastava Sanjay; Tamir Maya; McGonigal Kelly M.; John Oliver P.; Gross James J. 《Canadian Metallurgical Quarterly》2009,96(4):883
There is growing interest in understanding how emotion regulation affects adaptation. The present study examined expressive suppression (which involves inhibiting the overt expression of emotion) and how it affects a critical domain of adaptation, social functioning. This investigation focused on the transition to college, a time that presents a variety of emotional and social challenges. Analyses focused on 2 components of suppression: a stable component, representing individual differences expressed both before and after the transition, and a dynamic component, representing variance specific to the new college context. Both components of suppression predicted lower social support, less closeness to others, and lower social satisfaction. These findings were robustly corroborated across weekly experience reports, self-reports, and peer reports and are consistent with a theoretical framework that defines emotion regulation as a dynamic process shaped by both stable person factors and environmental demands. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
119.
Zn in Athenian Black Gloss Ceramic Slips: A Trace Element Marker for Fabrication Technology 下载免费PDF全文
Marc Walton Karen Trentelman Ilaria Cianchetta Jeffrey Maish David Saunders Brendan Foran Apurva Mehta 《Journal of the American Ceramic Society》2015,98(2):430-436
The black‐colored pottery slips produced in Athens from the 6th to 4th centuries B.C., had a consistent composition achieved through processing and refinement of raw clay. Little direct evidence has been established as to what were these refinement methods. To better understand how the slip material was prepared, the major and trace elemental compositions of 19 slips from different ceramic vessels and their corresponding bodies of Athenian red‐figure and black‐figure vases were determined using laser ablation inductively coupled plasma mass spectrometry (LA‐ICPMS). Notably higher Zn concentrations were found in the slips (271–1959 ppm) than in their corresponding body ceramics (<361 ppm). The Zn concentrations in the slips were also found to be above the natural background for typical clay (between 10 and 300 ppm) suggesting an unintentional anthropogenic enrichment of this metal. Based on the abnormally high Zn content of the slip, it is speculated that the clay was treated using vitriol (concentrated acid mine runoff which is rich in Zn), to induce flocculation and remove carbonate mineral phases from the raw material that, if present, would prevent the slip from vitrifying. This same signature of elevated levels of Zn with a corresponding Ce anomaly is also observed for black glosses produced in Corinthian and Etrurian (Italy) workshops indicating that these trace element signatures were imparted to the material by means of shared methods of manufacturing instead of being indicative of a single unique source for this material. 相似文献
120.