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排序方式: 共有232条查询结果,搜索用时 15 毫秒
21.
A. V. Prasadarao U. Selvaraj S. Komarneni A. S. Bhalla 《Ferroelectrics Letters Section》1992,14(3):65-72
Sol-gel thin films of La2Ti2O17 were deposited on fused silica and Si( 100) substrates by a spin-coating process. The La2Ti2O17 precursor solution for the spin-coating was prepared from lanthanum acetylacetonate and titanium iso-propoxide dissolved in 2-methoxyethanol. Crystalline and crack-free films of ∼ 0.3 μm thickness were deposited on the above sulastrates using a single coating and followed by annealing at a temperature of 800 "C. Microstructural studies revealed that these films contained extremely fine grains of ∼ 0.1 μm. Thin film X-ray diffraction patterns indicated the formation of grain oriented films along [100] direction on these substrates. 相似文献
22.
This article reports the environmentally benign synthesis of gold nanoparticles (GNPs) using methanol extract of Azolla microphylla as the stabilizing and reducing agent. The GNPs were characterized by UV-vis spectrophotometry and FTIR, and the morphological characteristics were analyzed by XRD, FESEM-EDX and HRTEM. The GNPs could be formed in very short time, even in less than 30 min. The nanoparticles measured by UV-spectrophotometer demonstrated a peak at 540 nm corresponding to surface plasmon resonance spectra, and the peaks showed by FTIR suggested the presence of organic biomolecules on the surface of the GNPs. XRD results confirmed the crystalline nature of the GNPs, and FESEM-EDX and HRTEM analyses had been performed in the size ranges of 17-40nm and 1.25-17.5nm respectively. The synthesized GNPs showed excellent antioxidant activity. This study shows the feasibility of using plant sources for the biosynthesis of GNPs. 相似文献
23.
Gold nanoparticles are reported and evaluated as probes for the detection of anticancer drug 6-mercaptopurine (6-MP). The nature of binding between 6-MP and the gold nanoparticles via complexation is investigated using ultraviolet-visible spectrum, cyclic voltammetry, transmission electron microscopy, fluorescence and Fourier transform infrared (FT-IR) spectroscopy. The bound antileukemic drug is fluorescent and the quenching property of gold nanoparticles could be exploited for biological investigations. The 6-MP-colloidal gold complex is observed to have appreciable antibacterial and antifungal activity against Micrococcus luteus, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Aspergillus fumigatus, and Aspergillus niger. The experimental studies suggest that gold nanoparticles have the potential to be used as effective carriers for anticancer drugs. 相似文献
24.
Ulagaraj Selvaraj Chun Ling Liu Sridhar Komarneni Rustum Roy 《Journal of the American Ceramic Society》1991,74(6):1378-1381
Glasses that are extremely difficult to crystallize are generally avoided in making glass-ceramics. It is now possible to crystallize such glasses epitaxially using isostructural seeds. The role of solid-state epitaxy in the crystallization of such albite (NaAlSi3 O8 ) glass to glass-ceramic was investigated. The glass was seeded with extremely fine ZrO2 (nonisostructural) and albite (isostructural) seed crystals. X-ray diffraction results indicated that the albite-seeded glass, heat-treated at 1000°C for 100 h, epitaxially crystallized to albite, while the ZrO2 and unseeded glasses did not crystallize in identical heat-treatment conditions. In addition, the albite-seeded glass, heat-treated at 905°C for 10 d, crystallized mostly to albite, whereas the ZrO2 and unseeded glasses at the same conditions contained only a small amount (<5 wt%) of nepheline (NaAlSiO4 ). The microstructure of the epitaxially grown glass-ceramics showed that extremely fine crystals (∼0.2 μm thickness) were formed around the seed. 相似文献
25.
Chemical modification of poly(vinyl chloride) (PVC) by dehydrochlorination with ethanolic KOH is found to yield modified PVC
with conjugated polyene sequence. The semiconducting nature of ethoxide-modified PVC is illustrated with temperature dependence
of conductivity (σ). The relative ratios (r) of conductivity,σ
modifiedpvc
/σ
unmodifiedpvc
, are greater than unity in the temperature range 50° to 180°C,r being maximum in the vicinity of glass-transition temperature (T
g).T
g inferred from conductivity-temperature profiles is found to be greater for modified PVC relative to unmodified PVC, which
is explicable in terms of restricted free rotation limiting segmental motion. For comparison with the conductivity andT
g of ethoxide-modified PVC, LiCl-modified PVC and (aniline + S2O
8
2−
)-modified PVC have also been studied. 相似文献
26.
The dibasic acids corresponding to the first double bond site in 16 vegetable and 6 animal fats were obtained by standardized
procedures, fractionated by liquid-liquid countercurrent extraction and individual fractions analyzed. Results show that the
site of the first double bond is not restricted exclusively or even predominantly to any single position but is spread over
three or more positions in major proportions. First double bond site distributions show large differences in different biological
species, different varieties from the same species and also different specimens from the same variety. Possible migration
of double bonds in permanganate oxidation at alkaline pH is discussed. 相似文献
27.
Govindasamy Kottur Selvaraj Venkatesan Ramasamy Shanmugasundaram Senthil Kumar Subramanian Murugesan 《Journal of the science of food and agriculture》2010,90(9):1533-1537
BACKGROUND: Quality of tea depends on the cultivar and climatic conditions. Biochemical pathways within the plant and climatic factors can result in noticeable changes in chemical composition, which determine the quality of tea. Black tea quality attributes are influenced by various forms of catechins, namely gallated, non‐gallated, dihydroxylated and trihydroxylated catechins and their ratios. Hence the variations in grouped catechins and their synthesizing enzyme in relation to quality of south Indian black tea grown in different seasons and different cultivars were studied. RESULTS: Gallated, non‐gallated, dihydroxylated, trihydroxylated catechins and catechin index were significantly higher in crop shoots harvested during summer. A significant and wide diversity in various forms of catechins was noticed among the cultivars tested. Among the cultivars, UPASI‐3 registered the higher amount of various forms of catechins and activity of phenylalanine ammonia lyase (PAL), followed by UPASI‐9 and UPASI‐17 respectively, while the lowest amount was exhibited by ‘Assam’ seedlings and TRI‐2043. CONCLUSION: Overall quality as evaluated by tea tasters was positively correlated to the cultivars and seasons tested. This positive correlation can be attributed to higher levels of grouped catechins and PAL activity. Thus the contents of various forms of catechins could be the most important quality parameter of the south Indian black teas. Copyright © 2010 Society of Chemical Industry 相似文献
28.
Direct incorporation of vanadium into three-dimensional KIT-6: 1. Optimization of synthesis conditions 总被引:1,自引:0,他引:1
Balasamy Rabindran Jermy Sang-Yun Kim Kanattukara Vijayan Bineesh Manickam Selvaraj Dae-Won Park 《Korean Journal of Chemical Engineering》2009,26(5):1235-1240
Three dimensional (3-D) cubic KIT-6 with directly incorporated vanadium was hydrothermally synthesized by using Pluronic P123
and n-butanol as the structure-directing mixture, tetraethyl orthosilicate (TEOS) as the silica source and NH4VO3 as the vanadium source. The molar composition was varied in the range of 0.017 P123/0.08–2.4 V/1.0–2.0 TEOS/1.31–1.70 BuOH/1.83–3.00
HCl/195 H2O. The orderness of mesopore structure was estimated by X-ray diffraction, N2 adsorption, and TEM analysis. The effects of the amount of HCl, TEOS and BuOH on the structure of KIT-6 were discussed. The
time and temperature for the synthesis of KIT-6 were also optimized. The amount of vanadium content influenced the framework
structure and crystallinity of the Ia3d phase significantly. 相似文献
29.
Balasamy Rabindran Jermy Sang-Yun Kim Kanattukara Vijayan Bineesh Manickam Selvaraj Seung-Kug Song Jong-Woo Ryu Dae-Won Park 《Korean Journal of Chemical Engineering》2009,26(5):1241-1245
The direct incorporation of vanadium into the three-dimensional (3-D) cubic Ia3d mesostructure designated as V-KIT-6 was prepared,
and the material obtained therein showed a very high specific surface area of ∼1,000 m2/g with tunable pore diameters in a narrow distribution of sizes, ∼5.7 to 6.0 nm. The coordination and nature of the V sites
in V-KIT-6 were characterized by 51V-spin-echo NMR analysis. It shows that after calcination, the V4+ species are totally oxidized to the V5+ state with 4- and 6-coordinated V-O environments in a highly dispersed state with much less crystalline V2O5 formation. The calcined V-KIT-6 materials showed excellent catalytic activity in the direct oxidation of styrene using tert-butyl
hydroperoxide (TBHP) as an oxidant. 相似文献
30.
Perumal Selvaraj Kumaresan Natesan Karuppanna Velusamy Thirumalachari Sundararajan 《传热工程》2019,40(1-2):193-201
To study the effect of irradiation on materials, sample coupons are irradiated in cyclotron facilities. During the irradiation process, these samples produce significant heat. This heat needs to be continuously removed from the samples in order to avoid melting of the samples as well as to keep the samples at a particular temperature during irradiation. The area available for heat transfer is limited due to small size of the samples. To increase the heat transfer rate, jet cooling is used as it provides large heat transfer co-efficient. To understand the heat transfer characteristics of jet cooling under these conditions, experiments have been carried out. Two inclined jets hitting on both sides of the target plate give maximum cooling and uniform temperature distribution. This paper gives the details of the numerical and experimental studies carried out and the discussions about the results obtained. 相似文献