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排序方式: 共有1399条查询结果,搜索用时 125 毫秒
51.
Arup Jyoti Das Prerna Khawas Tatsuro Miyaji Sankar Chandra Deka 《International Journal of Food Properties》2016,19(9):2087-2101
Phytochemicals content and antimicrobial activity of Artocarpus heterophyllus, Cyclosorus extensa, Oldendia corymbosa, and Alpinia malaccensis were investigated. Maximum alkaloids and terpenoids were found in A. heterophyllus; tannins and saponins in C. extensa; flavonoids, polyphenols, and phytosterols in O. corymbosa and anthraquinone, glycosides, and anthocyaninin A. malaccensis. Aqueous, methanolic, ethyl acetate, and hexane extracts were prepared from all the leaves. Attenuated total reflectance Fourier transform infrared spectrophotometric (ATR-FTIR) analysis revealed that alkanes and alkyl halides were prevalent in all the extracts and the ethyl acetate extracts contained comparatively higher number of functional groups, which were also more effective against Candida albicans, Escherichia coli, and Staphylococcus aureus. The minimum inhibitory concentration values of A. malaccensis against the tested pathogens were found to be lesser than the other species. 相似文献
52.
Material properties and operating configurations of membrane reactors for propane dehydrogenation
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Seung‐Won Choi Christopher W. Jones Sankar Nair David S. Sholl Jason S. Moore Yujun Liu Ravindra S. Dixit John G. Pendergast 《American Institute of Chemical Engineers》2015,61(3):922-935
A modeling‐based approach is presented to understand physically realistic and technologically interesting material properties and operating configurations of packed‐bed membrane reactors (PBMRs) for propane dehydrogenation (PDH). PBMRs composed of microporous or mesoporous membranes combined with a PDH catalyst are considered. The influence of reaction and membrane transport parameters, as well as operating parameters such as sweep flow and catalyst placement, are investigated to determine desired “operating windows” for isothermal and nonisothermal operation. Higher Damköhler (Da) and lower Péclet (Pe) numbers are generally helpful, but are much more beneficial with highly H2‐selective membranes rather than higher‐flux, lower‐selectivity membranes. H2‐selective membranes show a plateau region of conversion that can be overcome by a large sweep flow or countercurrent operation. The latter shows a complex trade‐off between kinetics and permeation, and is effective only in a limited window. H2‐selective PBMRs will greatly benefit from the fabrication of thin (~1 µm or less) membranes. © 2014 American Institute of Chemical Engineers AIChE J, 61: 922–935, 2015 相似文献
53.
Cobalt oxide thin films are prepared by the nebulizer spray pyrolysis technique using cobalt chloride as the precursor material. The structural, optical, morphological and electrical properties are investigated as a function of substrate temperature (300–450 °C). The X-ray diffraction (XRD) analysis reveals that all the films are polycrystalline in nature, having cubic structure with preferential orientation along the (111) plane. The optical spectra show that the films are transparent (68 %) in the IR region. The optical band gap values are calculated for different substrate temperature. Photoluminescence (PL) spectra of the films indicate the presence of indigo, blue and green emission peaks with an ultraviolet emission peak centered around 368nm. SEM images reveals small sphere-like structures for the prepared Co3O4 films. The maximum conductivity obtained is 1.48 x 10?3 S/cm at 350 °C. The activation energy varies between 0.039 and 0.138 eV for the substrate temperature variation from 300-450 Q°C. 相似文献
54.
I. Jerin Leno S. Saravana Sankar S. G. Ponnambalam 《The International Journal of Advanced Manufacturing Technology》2016,84(5-8):787-799
A well-planned arrangement of manufacturing departments on a two-dimensional planar region considerably increases the efficiency of its production systems, which is termed facility layout problem (FLP). Conventional layout design approach often designs intercell layout (determining exact location of each department on shop floor area) and flow path layout design of material handling system (MHS) step by step in a sequential manner. This results in suboptimal solutions for FLP. In this paper, an integrated approach is adopted to design the intercell layout and the flow path layout of MHS simultaneously. The quality of the final layout is evaluated by minimizing total material handling cost. Sequence pair (SP) representation is used for layout encoding. The translation from SP to layout is efficiently made by longest common subsequence (LCS) methodology. An elitist strategy genetic algorithm using simulated annealing (E-GASAA) as a local search mechanism is developed and tested with four test problem instances available in the literature. Elitist strategy is incorporated to enhance convergence characteristic of the proposed algorithm. It is found that the proposed E-GASAA is able to produce best solutions consistently for the test problem instance of different sizes within acceptable computational effort. In addition to that, we tried to reduce the computational load with the help of adopted LCS computation methodology and achieved a good improvement. 相似文献
55.
Jayeeta Chattopadhyay Tara Sankar Pathak Daewon Pak Rohit Srivastava 《Korean Journal of Chemical Engineering》2016,33(5):1514-1529
Metal micro-/nano hollow spheres have been widely applied in numerous fields during the last decade. This review will only focus on the synthetic strategies to synthesize hollow spherical structures in the enhancement of their electrocatalytic activity, especially the metal hollow spherical materials. We present a comprehensive overview of synthetic strategies for metal hollow spherical structures which have been approached specifically in electrochemical reactions. These synthetic methods are mainly categorized as hard templates, soft templates, sacrificial templates and without templates. The review further includes electrocatalytic approaches of hollow spherical metals in different electrochemical processes, especially the methanol electro-oxidation reaction for methanol fuel cell application and hydrogen and oxygen evolution reactions in water electrolyzer, as metal hollow spherical materials are especially applied in these specific reactions. 相似文献
56.
Sellamuthu N. Jaisankar Neelamegan Haridharan Adhigan Murali Ponyrko Sergii Milena Špírková Asit Baran Mandal Libor Matějka 《Polymer》2014
The sidewall functionalization of single-walled carbon nanotubes (SWCNTs) was established by poly (methyl methacrylate) (PMMA) using controlled radical polymerization (CRP) method. A bromide functionalized SWCNT (SWCNT-Br) has been used as an initiator for the synthesis of SWCNT-graft-PMMA (SWCNT-g-PMMA). The efficiency of the sacrificial initiator (S) was monitored during the polymerization process. The obtained polymers possess a uniform distribution of molecular weight with a lower polydispersity index of 1.36. The SWCNTs-based initiator acts as an efficient medium for the controlled growth of polymer on the SWCNTs surfaces. The presence of bimodal gel permeation chromatographic (GPC) curve for the SWCNT-g-PMMA(S) obtained through sacrificial initiator (S) confirms uncontrolled behavior. However, the clear sharp peak for SWCNT-g-PMMA obtained without sacrificial initiator shows its well-controlled process of polymerization, which acts as a mimic to bone cement. The efficiency of the functionalization of SWCNT and the controlled formation of SWCNT-g-PMMA composites were characterized by TGA, Raman, TEM, NMR, XPS and dispersion measurements. 相似文献
57.
Differential scanning calorimetric studies on structured lipids from coconut oil triglycerides containing stearic acid 总被引:1,自引:0,他引:1
Reena Rao Kadimi Udaya Sankar Kari Sambaiah B. R. Lokesh 《European Food Research and Technology》2001,212(3):334-343
Triglycerides from coconut oil contain high levels of lauric acid. They were replaced by incremental amounts of stearic acid by interesterification reactions catalyzed by immobilized lipase (IM 60 from Rhizomucor miehei). The reactions were carried out in organic solvents such as hexane. Maximum incorporation of stearic acid was observed by 4 h at 37vv°C or by 2 h at 60vv°C when triglycerides to fatty acid (stearic acid) ratio was maintained at 1v:Ң. The stearic acid level in coconut oil triglycerides was increased from an initial value of 2% to 60% under these conditions. The stearic acid replaced lauric, myristic, and palmitic acids in unmodified triglycerides. A major portion of stearic acid incorporated was found in positions 1 and 3 of triglycerides. Differential scanning calorimetry indicated that stearic acid enrichment increased the solid fat content and also the higher melting polymorphs in modified lipids. The studies also indicated that low melting polymorphic forms of coconut oil triglycerides are converted to higher melting forms by stearic acid enrichment. The modified lipids thus obtained can find use in various food applications. 相似文献
58.
Based onin-situ Mössbauer and X-ray diffraction studies, it is shown that in the Fe/TiO2 catalyst, the anatase-rutile transformation of the TiO2 support is facilitated by the Fe2+ ions formed during the reduction. The transformation occurs at lower temperatures in Th/TiO2 and Cu/TiO2 compared to pure TiO2. In general, the transformation of anatase to rutile seems to occur at or below the temperature (770 K) at which strong-metal-support-interaction manifests itself.Contribution No. 718 from the Solid State and Structural Chemistry Unit. 相似文献
59.
J. T. Venkatraman D. Pehowich B. Singh R. V. Rajotte A. B. R. Thomson M. T. Clandinin 《Lipids》1991,26(6):441-444
Experimental diabetes may manifest itself in a defect in liver microsomal fatty acid desaturation and increased activity of
glucose-6-phosphatase (G-6-Pase). The present study was designed to determine whether these changes could be normalized by
a change in the dietary fat consumed. Control and streptozotocin-induced diabetic rats were fed nutritionally adequate diets
which varied in fatty acid composition. Fatty acid analysis of liver microsomal phospholipids revealed that non-diabetic control
animals fed saturated fat (beef tallow) or a diet high in ω3 fatty acids (fish oil) exhibited a significantly higher level
of 18∶2ω6 and a lower level of 20∶4ω6 in the phosphatidylcholine and phosphatidylethanolamine fractions compared with diabetic
animals. Control and diabetic animals fed the high linoleic acid diet had similar levels of 18∶2ω6 in the microsomal phosphatidylcholine
and phosphatidylserine fractions. Microsomal G-6-Pase activity was higher in diabetic than in control animals. Activity of
G-6-Pase was lower in microsomes of control animals fed the soybean oil or the fish oil diet, but was not significantly reduced
in diabetic animals fed high polyunsaturated fats. Blood glucose levels were similar in control groups fed the different diets,
but the plasma hemoglobin A1c level was lower in diabetic animals fed the soybean oil diet. Cholesterol and triglyceride levels
were lower in diabetic animals fed the fish oil-based diet. The results suggest that dietary fat manipulation has the potential
to change at least some of the abnormalities in the microsomal membrane in experimental diabetes. 相似文献
60.
Blends of linear low density polyethylene (LLDPE) and ethylene-co-methyl acrylate (EMA) having 60/40 composition was studied
with and without compatibilizing agent. The compatibilizing agent used was maleic anhydride grafted linear low density polyethylene
(LLDPE-g-MA). The LLDPE backbones of the compatibilizer are compatible with LLDPE blend component, whereas the maleic anhydride
is affinated with carbonyl groups of EMA. The effectiveness of the compatibilizing agent was evaluated using different techniques
like mechanical, thermal, scanning electron microscopy and rheological studies. Best compatibilization effect was found in
the blend at a loading of 3 wt% of compatibilizer since at this level of compatibilizer complex viscosity, tensile strength,
modulus, elongation at break, impact strength was found to be higher. The increase in the melt viscosity, storage modulus
and thermal stability of the compatibilized blends indicated enhanced interactions between the discrete LLDPE and EMA phases
induced by the functional compatibilizer. 相似文献