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排序方式: 共有138条查询结果,搜索用时 46 毫秒
1.
2.
Analysis of corrosion resistance behavior of inhibitors in concrete using electrochemical techniques
Reinforced concrete is one of the most durable and cost effective construction materials. However, in high chloride environments,
it can suffer from corrosion due to chloride induced breakdown of the normal passive layer protecting the reinforcing steel
bars inside concrete. One means of protecting embedded steel reinforcement from chloride induced corrosion is the addition
of corrosion inhibiting admixtures. In the present investigation, various inhibitors such as sodium nitrite, zinc oxide, mono
ethanol amine, diethanolamine, and triethanol amine have been used in concrete in different percentages. Their effectiveness
was then studied using various electrochemical techniques such as rapid chloride ion penetration test, open circuit potential
measurement, electrochemical impedance measurement, potentiodynamic polarization measurement, and gravimetric weight loss
measurement. The results thus obtained indicate that the addition of inhibitors enhances the corrosion resistance properties. 相似文献
3.
Ramanathan Saraswathy 《材料科学前沿(英文版)》2017,11(4):385-394
Synthesis of nanostructured Ru-doped SnO2 was successfully carried out using the reverse microemulsion method. The phase purity and the crystallite size were analyzed by XRD. The surface morphology and the microstructure of synthesized nanoparticles were analyzed by SEM and TEM. The vibration mode of nanoparticles was investigated using FTIR and Raman studies. The electrochemical behavior of the Ru-doped SnO2 electrode was evaluated in a 0.1 mol/L Na2SO4 solution using cyclic voltammetry. The 5% Ru-doped SnO2 electrode exhibited a high specific capacitance of 535.6 F/g at a scan rate 20 mV/s, possessing good conductivity as well as the electrocycling stability. The Ru-doped SnO2 composite shows excellent electrochemical properties, suggesting that this composite is a promising material for supercapacitors. 相似文献
4.
Evaluation of Crop Models for Simulating and Optimizing Deficit Irrigation Systems in Arid and Semi-arid Countries Under Climate Variability 总被引:2,自引:2,他引:0
Sebastian?KlossEmail author Raji?Pushpalatha Kefasi?J.?Kamoyo Niels?Schütze 《Water Resources Management》2012,26(4):997-1014
The variability of fresh water availability in arid and semi-arid countries poses a serious challenge to farmers to cope with
when depending on irrigation for crop growing. This has shifted the focus onto improving irrigation management and water productivity
(WP) through controlled deficit irrigation (DI). DI can be conceived as a strategy to deal with these challenges but more
knowledge on risks and chances of this strategy is urgently needed. The availability of simulation models that can reliably
predict crop yield under the influence of soil, atmosphere, irrigation, and agricultural management practices is a prerequisite
for deriving reliable and effective deficit irrigation strategies. In this context, this article discusses the performance
of the crop models CropWat, PILOTE, Daisy, and APSIM when being part of a stochastic simulation-based approach to improve
WP by focusing primarily on the impact of climate variability. The stochastic framework consists of: (i) a weather generator
for simulating regional impacts of climate variability; (ii) a tailor-made evolutionary optimization algorithm for optimal
irrigation scheduling with limited water supply; and (iii) the above mentioned models for simulating water transport and crop
growth in a sound manner. The results present stochastic crop water production functions (SCWPFs) that can be used as basic
tools for assessing the impact on the risk for the potential yield due to water stress and climate variability. Example simulations
from India, Malawi, France and Oman are presented and the suitability of these crop models to be employed in a framework for
optimizing WP is evaluated. 相似文献
5.
Using photo acoustic technique, the thermal properties of CdS thin films grown by spray pyrolysis are measured. Thermal diffusivity
and conductivity in these films decrease at least two orders compared with bulk. These results are compared with our study
on nano CdS and the other available literature. The comparison is good. The dependence of thermal diffusivity on the thickness
of the layer or the size of the particles on the glass substrate are analysed from the present measurement and discussed.
The dependence of thermal diffusivity on the thickness of the layer on the glass substrate is discussed. 相似文献
6.
Phosphating is one of the most important chemical conversion treatments for steel, mainly to improve corrosion resistance and paint adhesion and as an absorbing layer for waxes, oils, lacquers, etc. However, phosphate coating are crystalline and porous and need a sealing treatment after phosphating. Chromate sealing is a well known practice, and due to its toxicity, development of an ecofriendly sealing treatment is very essential. This paper focuses on the effect of zinc phosphate chemical conversion coating with the addition of nano-SiO2 to protect the mild steel rebars against corrosion in chloride contaminated concrete. The coated surfaces were characterised by scanning electron microscopy and X-ray diffraction. Corrosion resistances of coated and uncoated rebars were evaluated by anodic polarisation, linear polarisation resistance, Tafel and alternating current impedance spectroscopy and cyclic polarisation technique. The results indicated that the coated rebars have considerably reduced the corrosion rate even in the presence of 3% chloride environments. 相似文献
7.
Rajangam Vinodh Prem Jyoti Sing Rana Chandu VV Muralee Gopi Zongmin Yang Raji Atchudan Kandan Venkatachalam Hee‐Je Kim 《Polymer International》2019,68(5):929-935
We successfully synthesized 13X zeolite using a hydrothermal method. Then, composites of polyaniline (PANI) with 13X zeolite and PANI–13X with platinum were prepared by chemical oxidative polymerization and chemical reduction, respectively. Field emission scanning electron microscopy, X‐ray diffraction, Raman spectroscopy and Brunauer–Emmett–Teller techniques were used to characterize the PANI–Pt and PANI–Pt–13X composites. Further, the electrocatalytic activity towards methanol oxidation of the synthesized catalysts was explored using cyclic voltammetry in 1 mol L?1 CH3OH + 0.5 mol L?1 H2SO4 solution. From the obtained results, PANI–Pt–13X shows superior performance compared to PANI–Pt towards methanol oxidation and electrical conductivity. Hence, the 13X zeolite‐incorporated PANI–Pt composite could be an efficient catalyst for direct methanol fuel cell applications. © 2019 Society of Chemical Industry 相似文献
8.
Igor Jerković Marina Rajić Zvonimir Marijanović Mate Bilić Stela Jokić 《分离科学与技术》2016,51(18):2925-2931
Supercritical (SC) CO2 extraction of dried Immortelle flowers was performed at different process parameters. The optimal extraction conditions related to the yield were determined by response surface methodology (yield 4.09% at 20 MPa and 52°C). The extracts were analyzed by GC-MS and tremetone derivatives dominated: bitalin A, 12-acetoxytremetone, gnaphaliol, 1-[2-(2-methyl-2,3-dihydroxypropyl)-2,3-dihydro-1-benzofuran-5-yl]ethanone, isobutyl bitalin A, and 1-[2-(acetylprop-1-en-2-yl)-3-hydroxy-2,3-dihydro-1-benzofuran-5-yl]ethanone. Striking differences were found among the essential oil and SC-CO2 extracts composition. The major oil compounds were γ-curcumene, α-pinene, β-selinene, α-selinene, and limonene. Mono- and sesquiterpene were found among minor constituents of the extracts. Neryl acetate was present in the extracts and essential oil. 相似文献
9.
Raji Vijayan Loganathan Chitra Sakayanathan Penislusshiyan 《International Journal of Food Properties》2018,21(1):674-684
Bioactive fraction of brown algae Sargassum wightii (SWE) was obtained using silica column chromatography and preparative Thin Layer Chromatography (TLC). FT-IR and LC–mass spectrometry ESI analysis revealed presence of various phlorotannins in the SWE. The IC50 value of SWE was found to be 59.91, 51.04, and 55.21 μg/ml for scavenging of 2,2-diphenyl-1-picrylhydrazyl, 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid), and Ferric Reducing Antioxidant Power assay, respectively. SWE inhibited angiotensin-I-converting enzyme (ACE) in mixed-type manner with IC50 value of 56.96 µg/ml and Ki value of 45 µg/ml. The dual function such as antioxidant and ACE inhibition of SWE warrants further study to understand the antihypertensive potential in vivo. 相似文献
10.
Moisture sorption isotherms of EX-BORNO and SOSAT C88 millets at temperature range of 30–70 °C and water activity range of 0.07–0.98 were determined using the static gravimetric method. The sorption isotherms of both millet varieties decreased with increasing temperature, exhibited type II behaviour according to BET classification and hysteresis having loop size increasing with increasing temperature. This is as a result of the hard nature of the millet varieties. The moisture sorption and the data fitted well with Modified Henderson, Modified Halsey, Modified Oswin and Modified GAB models. The constants of the equations used in fitting were determined by non-linear regression analysis when the models were compared using the standard error of estimate, mean relative percent deviation, fraction explained variation and residual plots. The Modified Oswin model gave the best fit for the whole set of data. The study has provided information and data useful in large scale drying and processing of millet which have remained at the traditional level despite the importance of the drought resistance crop in poverty alleviation. 相似文献