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排序方式: 共有623条查询结果,搜索用时 203 毫秒
31.
Sangeetha Jayakumar T. Nandakumar M. Vadivel C. Thinaharan Rani P. George 《Journal of Adhesion Science and Technology》2020,34(7):713-743
AbstractWe report, here, the corrosion inhibition of mild steel specimen in 1?M HCl by tamarind fruit pulp aqueous (TFPA) extract. The inhibition property in the presence of TFPA extract is studied using weight loss, polarization measurement and electrochemical impedance spectroscopy (EIS). The inhibitor efficiency is found to vary from 74% to 88% (weight loss method) with TFPA concentration of 100–600?ppm. The reduction in Tafel slopes shows that TFPA acts as a mixed-type inhibitor. The adsorption of the inhibitor on the metal surface follows Langmuir isotherm. The standard Gibbs free energy of adsorption value of –40?kJ/mol suggests the chemisorption of inhibitor molecules via coordinate bond. AFM results exhibit a decrease in the surface roughness of mild steel, exposed to 1?M HCl from 299?±?12 to 154?±?6.6?nm, with increasing concentration of inhibitor from 0 to 600?ppm due to the uniform coverage of inhibitor molecules on the metal surface. X-ray photoelectron spectroscopy de-convoluted high resolution profiles of C 1?s (carbon) for mild steel exposed to 1?M HCl with 600?ppm inhibitor show major peaks corresponding to sp3 C–C/C–H (284.9?eV) and oxygen bondings in C–OH, C=O, COOH with a binding energy of 285.9, 286.9, 288.5?eV, respectively, thereby confirming the adsorption of organic moieties on mild steel surface. Fourier transform infrared spectroscopy further confirms the adsorption of inhibitor molecules on the metal surface. Therefore, tamarind fruit pulp extract is a potential corrosion inhibitor for mild steel, which is cost-effective, green and non-toxic. 相似文献
32.
Alessia Costa Barbara Rani Thomaz F. S. Bastiaanssen Francesco Bonfiglio Eoin Gunnigle Gustavo Provensi Moira Rossitto Marcus Boehme Conall Strain Clara S. Martínez Patrizio Blandina John F. Cryan Sophie Lay Renato Corradetti Maria Beatrice Passani 《International journal of molecular sciences》2022,23(2)
Exposure to repeated social stress may cause maladaptive emotional reactions that can be reduced by healthy nutritional supplementation. Histaminergic neurotransmission has a central role in orchestrating specific behavioural responses depending on the homeostatic state of a subject, but it remains to be established if it participates in the protective effects against the insults of chronic stress afforded by a healthy diet. By using C57BL/6J male mice that do not synthesize histamine (Hdc−/−) and their wild type (Hdc+/+) congeners we evaluated if the histaminergic system participates in the protective action of a diet enriched with polyunsaturated fatty acids and vitamin A on the deleterious effect of chronic stress. Behavioural tests across domains relevant to cognition and anxiety were performed. Hippocampal synaptic plasticity, cytokine expression, hippocampal fatty acids, oxylipins and microbiota composition were also assessed. Chronic stress induced social avoidance, poor recognition memory, affected hippocampal long-term potentiation, changed the microbiota profile, brain cytokines, fatty acid and oxylipins composition of both Hdc−/− and Hdc+/+ mice. Dietary enrichment counteracted stress-induced deficits only in Hdc+/+ mice as histamine deficiency prevented almost all the diet-related beneficial effects. Interpretation: Our results reveal a previously unexplored and novel role for brain histamine as a mediator of many favorable effects of the enriched diet. These data present long-reaching perspectives in the field of nutritional neuropsychopharmacology. 相似文献
33.
Heavy metal accumulation in vegetables irrigated with water from different sources 总被引:12,自引:0,他引:12
Monu Arora Bala Kiran Shweta Rani Anchal Rani Barinder Kaur Neeraj Mittal 《Food chemistry》2008,111(4):811-815
The present study was carried out to assess levels of different heavy metals like iron, manganese, copper and zinc, in vegetables irrigated with water from different sources. The results indicated a substantial build-up of heavy metals in vegetables irrigated with wastewater. The range of various metals in wastewater-irrigated plants was 116–378, 12–69, 5.2–16.8 and 22–46 mg/kg for iron (Fe), manganese (Mn), copper (Cu) and zinc (Zn), respectively. The highest mean levels of Fe and Mn were detected in mint and spinach, whereas the levels of Cu and Zn were highest in carrot. The present study highlights that both adults and children consuming vegetables grown in wastewater-irrigated soils ingest significant amount of these metals. However, the values of these metals were below the recommended maximum tolerable levels proposed by the [Joint FAO/WHO Expert Committee on Food Additives (1999). Summary and conclusions. In 53rd Meeting, Rome, June 1–10, 1999]. However, the regular monitoring of levels of these metals from effluents and sewage, in vegetables and in other food materials is essential to prevent excessive build-up of these metals in the food chain. 相似文献
34.
Yew Joon Tam Morvarid Akhavan Rezaei Mohd Lila Mohd Azmi Abdul Rani Bahaman Sewn Cen Lo 《分离科学与技术》2016,51(5):816-829
Univariate screening on factors affecting the purification performance of recombinant hepatitis B surface antigen (HBsAg) on ion exchange chromatography (IEC) and size exclusion chromatography (SEC) and the establishment of a two-step purification strategy were performed. Amongst four IEC adsorbents examined, the use of Q Sepharose XL IEC adsorbent under optimized conditions together with optimized SEC purification was able to efficiently purify HBsAg. An established purification strategy comprising the two techniques further demonstrated adaptability for scale-up operations with a final total purification factor (PF) of 94.82 ± 16.20, HBsAg purity of 95.48% and recovery yield of 78.07%. 相似文献
35.
Galvanic black anodizing on Mg-Li alloys 总被引:7,自引:0,他引:7
A. K. Sharma R. Uma Rani H. Bhojaraj H. Narayanamurthy 《Journal of Applied Electrochemistry》1993,23(5):500-507
A process of galvanic black anodizing on Mg-Li alloys was studied. The influence of various operating parameters, namely galvanic current density, voltage, pH, electrolyte concentration, operating temperature, anodizing time and heat treatment on the anodic film formation have been investigated to optimize the process. The deposits were characterized by optical and scanning electron microscopy, adhesion tests, corrosion studies, thickness measurement and microhardness evaluation. The space worthiness of the coatings has been evaluated by humidity, thermal cycling and thermovacuum tests and measurement of optical properties. The results of all these studies are clearly indicative that the black anodizing process described herein is extremely suitable for ground, as well as space, applications.Nomenclature s
Solar absorbance
- ir
Infrared emittance
-
VHN
Vickers hardness number 相似文献
36.
The research reported in this paper is concerned with gaining a better understanding of human factors issues in machining and the automation of manufacturing tasks. Mismatches between operators' performance and the requirements of machining tasks were experimentally studied with respect to the relationships with various human characteristics, including skill, age, work experience, self-confidence and trust. Twelve hypotheses concerning interrelationships between these characteristics were evaluated and important relationships established. It is considered that this increased knowledge of the rate of mismatches and an understanding of the causes is essential for the successful design of new working environments, machines and tasks. Much of this change to the working environment is likely to involve some degree of automation of the operators' tasks and so a second and important aspect of the study was designed to establish the extent to which preferred levels of automation were related to the same human characteristics. Four further hypotheses relating preferred levels of automation to skill, age, work experience, self-confidence and trust were tested with results that, in some cases, were unexpected and in others contradict the findings of previous research. 相似文献
37.
Sachin D. Kore P. P. Date S. V. Kulkarni Satendra Kumar Dolly Rani M. R. Kulkarni S. V. Desai R. K. Rajawat K. V. Nagesh D. P. Chakravarty 《The International Journal of Advanced Manufacturing Technology》2011,54(9-12):949-955
The ability to manufacture a product using different metal combinations greatly increases flexibility in design and production. Joining of dissimilar metal combinations like Copper-to-Stainless Steel (Cu-to-SS) is, however, a challenging task owing to the large differences in physical and chemical properties. The application of electromagnetic (EM) impact technique is demonstrated for welding copper (Cu) to stainless steel (SS) sheets. The welding Cu-to-SS is accomplished by using Al drivers to accelerate Cu and SS work sheets. The tensile shear strength test and the metallographic studies are carried out for Cu-to-SS EM welds. 相似文献
38.
39.
Studies on the growth and stability of silver nanoparticles synthesized by electron beam irradiation
Manjunatha Pattabi Rani M. Pattabi Ganesh Sanjeev 《Journal of Materials Science: Materials in Electronics》2009,20(12):1233-1238
Stable Ag nanoparticles have been synthesized by irradiating an aqueous solution of AgNO3 and Poly-vinyl alcohol (PVA) with 8 MeV electrons from a Microtron. The rate of formation of nanoparticles could be controlled by changing either the irradiation dosage or the relative concentration of the precursors. The size, shape, and the rate of formation of the nanoparticles depend on the final dosage, as well as the weight ratio of AgNO3 and PVA. The formation of Ag nanoparticles and their size were established through UV–Vis spectroscopy and Transmission electron microscopy (TEM) analysis, respectively. Increasing the irradiation dosage seem to favour the formation of polygonal nanostructures. Differential scanning calorimetry (DSC) measurements show that there exists a strong interaction between the PVA matrix and the Ag nanoparticles. 相似文献
40.
Suman Rani Neetu Ahlawat R. Punia Kanta Maan Sangwan Sunita Rani 《Ceramics International》2018,44(6):5996-6001
In this work, Sr and Zn co-doped calcium copper titanate having nominal formula Ca0.90Sr0.10Cu3Ti3.95Zn0.05O12 has been synthesized and systematically studied for structure, dielectric and electrical properties. The phase purity of the prepared composition has been confirmed by X-ray diffraction (XRD) pattern and various structural parameters are presented here with Rietveld refinement data. The Scanning electron microscopy (SEM) image revealed the presence of homogeneous fine-grained microstructure investigated in the prepared ceramic. The impedance data well fitted with 2 R-CPE model confirmed the non-ideality of the system. Dielectric studies have shown the existence of two relaxation processes in low and high frequency domains. Low frequency dielectric response proposed as a combination of Maxwell-Wagner relaxation and intrinsic defect (Vo++) while high frequency behavior has been interpreted in terms of polaronic relaxation caused by hopping process of an electron between Ti3+ and Ti4+ states. The frequency dependent behavior of conductivity has been well fitted to Dong’s model and interpreted in term of Overlapping Large Polaron Tunneling (OLPT) mechanism. The various parameters; relaxation angular frequency (ω1) of Debye process, ionic hopping frequency (ω2), dc conductivity (σo), cole- cole parameter (α) and frequency exponent (s) have been determined by Dong’s Model fitting. 相似文献