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111.
Flammability of epoxy appears to be one of the greatest threats and hence limits its advanced applications. The present investigation, therefore, reports on vegetable oil-based self-extinguishing epoxy/clay nanocomposites for the first time. These nanocomposites were prepared by the ex-situ technique using mechanical shearing and ultrasonication at different loadings (1, 2.5 and 5 wt%) of nano-clay. Monoglyceride of Mesua ferrea L. seed oil, bisphenol-A and tetrabromobisphenol-A based epoxy resin was used as the matrix. XRD, TEM, SEM, FTIR and rheological studies confirmed partially exfoliated nanocomposites formation. The study demonstrates two fold improvements of tensile strength and scratch hardness, three-fold increase in adhesive strength and 20 units increase in gloss value without any change in impact resistance through nanocomposite formation. TG studied confirmed the enhancement of thermal stability of the nanocomposite by 25 °C. The limiting oxygen index values and UL 94 test indicated the self-extinguishing characteristic of the nanocomposites. 相似文献
112.
Sanjeev Gautam Anup Thakur D.K. Shukla H.J. Shin Keun Hwa Chae K.P. Singh Navdeep Goyal 《Journal of Non》2011,357(11-13):2340-2343
This paper reports the effect of proton irradiation on the electrical properties of a-As2S3 in the temperature range of 323–418 K and frequency range 0.1–100 kHz. The variation of transport property is studied with proton irradiation dose (1 × 1013 ions/cm2 and 1 × 1015 ions/cm2). It has been observed that proton irradiation changes the dc conductivity (σdc), dc activation energy (ΔEdc) and ac conductivity (σac(ω)). The σdc and σac(ω) increases with dose of proton irradiation. The value of frequency exponent (s) decreases with the temperature and irradiation dose. These results are explained in terms of change in density of defect states in these glasses. 相似文献
113.
Sanjeev Gautam Shanshank N. Kane B.–G. Park J.–Y. Kim L.K. Varga J.–H. Song Keun Hwa Chae 《Journal of Non》2011,357(11-13):2228-2231
This paper reports x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) studies at Fe L3,2 and Co L3,2-edges to investigate the electronic structure of (Fe100 ? xCox)78Si9Nb3B9Cu1 (0 < x < 95) alloys. The influence of controlled Co addition on electronic structural and magnetic properties of (Fe100 ? xCox)78Si9Nb3B9Cu1 (x = 0, 20, 40, and 60) alloys has been investigated and it has been observed that Co exists as Co2+/Co3+, while Fe exists as a mixture of Fe0 (metallic) and Fe2+. The XMCD studies confirm these results and reveal that Co-ions are responsible for the room temperature ferromagnetism (RTFM) in the system, while at Fe L3,2-edge it shows a diamagnetic behavior. 相似文献
114.
We wish to study the problem of bumping outwards a pseudoconvex, finite-type domain in such a way that pseudoconvexity is preserved and such that the lowest possible orders of contact of the bumped domain
with ∂Ω, at the site of the bumping, are explicitly realised. Generally, when , the known methods lead to bumpings with high orders of contact—which are not explicitly known either—at the site of the
bumping. Precise orders are known for h-extendible/semiregular domains. This paper is motivated by certain families of non-semiregular domains in . These families are identified by the behaviour of the least-weight plurisubharmonic polynomial in the Catlin normal form.
Accordingly, we study how to perturb certain homogeneous plurisubharmonic polynomials without destroying plurisubharmonicity.
The first-named author is supported by a grant from the UGC under DSA-SAP, Phase IV. 相似文献
115.
Dechlorination of DDT, DDD and DDE in soil (slurry) phase using magnesium/palladium system 总被引:2,自引:0,他引:2
Mg0/Pd4+ was able to dechlorinate >99% of extractable DDT (initial concentration of 10 mg DDT kg(-1) of soil) and >90% of extractable DDT (initial concentration of 50 mg DDT kg(-1) of soil) in soil slurry. Mg0/Pd4+ was also found to be effective in dechlorinating of 50 mg kg(-1) DDD and DDE, in soil aged for varying time periods. GC-MS analyses revealed the formation of 1,1-diphenylethane as an end product from DDT, DDE and DDD. To the best of our knowledge this is the first report describing the application Mg0/Pd4+ system for remediation of DDT, DDD and DDE contaminated soil. We conclude that reductive dechlorination reaction catalyzed by Mg0/Pd4+ may be a promising system to remediate soil contaminated with DDT and its dechlorinated products such as DDD and DDE. 相似文献
116.
Sirtinol, a Schiff base derived from 2-hydroxy-1-naphthaldehyde, is an inhibitor of sirtuin proteins, a family of deacetylases active in gene regulation and relevant to the study of cancer growth. The formation of copper(II) and zinc(II) complexes of sirtinol is investigated by spectroscopic and structural methods. The molecular structure of this protein inhibitor allows for coordination of first-row transition metals in both tridentate and bidentate fashion. In addition, assays in cultured breast cancer cells reveal that CuII(sirtinol?H)2 and previously reported FeIII(sirtinol?H)(NO3)2 present enhanced cytotoxicity when compared to the free ligand, and that the ferric complex causes an increase in intracellular oxidative stress. Transition metal coordination in the biological milieu could therefore contribute additional effects to the biological profile of sirtinol. 相似文献
117.
We study the directed transverse flow for mass asymmetry reactions. This is done by keeping the target fixed and varying the projectile mass from 4He to 131Xe. We find that directed transverse flow is sensitive to the mass of the projectile. We also study the disappearance of flow at a particular impact parameter called Geometry of Vanishing Flow (GVF) for such mass asymmetry reactions. Our results indicate that GVF is sensitive to the beam energy as well as to the mass of the projectile. 相似文献
118.
Parmod Kumar Yogesh Kumar Hitendra K. Malik S. Annapoorni Sanjeev Gautam Keun Hwa Chae K. Asokan 《Applied Physics A: Materials Science & Processing》2014,114(2):453-457
Room-temperature multiferroic properties in Mg-doped ZnO samples are reported wherein Mg replaces Zn in the ZnO matrix and retains hexagonal wurtzite structure. The saturation magnetisation is increased from ~2×10?4 emu/g to 3×10?4 emu/g for the dilute doping of 2 % Mg in pure ZnO and the ferroelectricity is also increased. Higher concentration of Mg does not lead to a significant enhancement in the magnetisation but improves the ferroelectric properties. An X-ray absorption spectroscopic study shows an enhancement in O vacancies with dilute doping of Mg. The origin of the multiferroic behaviour is understood based on their crystal and electronic structures. 相似文献
119.
A new homoisoflavonoid, isointricatinol (1), together with eight known homoisoflavonoids, three flavonoids, bergenin and 11-O-galloylbergenin were isolated from the EtOAc fraction of MeOH extract of Caesalpinia digyna roots and evaluated for the antioxidant activity against DPPH and ABTS free radicals. The structure of 1 was elucidated by various spectroscopic techniques and found to be a Z-isomer of 7,8-dihydroxy-3-(4'-methoxybenzyl)chroman-4-one. Compound 1 was found to exhibit mild to moderate free radical scavenging effect against DPPH (IC(50), 85.50?μM) and ABTS (IC(50), 44.13?μM) radicals. 相似文献
120.
Srinu Tothadi Balakrishna R. Bhogala Asha R. Gorantla Tejender S. Thakur Ram K. R. Jetti Gautam R. Desiraju 《化学:亚洲杂志》2012,7(2):330-342
The crystal polymorphism of the anthelmintic drug, triclabendazole ( TCB ), is described. Two anhydrates (Forms I and II), three solvates, and an amorphous form have been previously mentioned. This study reports the crystal structures of Forms I ( 1 ) and II ( 2 ). These structures illustrate the uncommon phenomenon of tautomeric polymorphism. TCB exists as two tautomers A and B. Form I (Z′=2) is composed of two molecules of tautomer A while Form II (Z′=1) contains a 1:1 mixture of A and B. The polymorphs are also characterized by using other solid‐state techniques (differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), PXRD, FT‐IR, and NMR spectroscopy). Form I is the higher melting form (m.p.: 177 °C, ΔHf=≈105±4 J g?1) and is the more stable form at room temperature. Form II is the lower melting polymorph (m.p.: 166 °C, ΔHf=≈86±3 J g?1) and shows high kinetic stability on storage in comparison to the amorphous form but it transforms readily into Form I in a solution‐mediated process. Crystal structure analysis of co‐crystals 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 further confirms the existence of tautomeric polymorphism in TCB . In 3 and 11 , tautomer A is present whereas in 4 , 5 , 6 , 7 , 8 , 9 , 10 the TCB molecule exists wholly as tautomer B. The DFT calculations suggest that the optimized tautomers A and B have nearly the same energies. Single point energy calculations reveal that tautomer A (in Form I) exists in two low‐energy conformations, whereas in Form II both tautomers A and B exist in an unfavorable high‐energy conformation, stabilized by a five‐point dimer synthon. The structural and thermodynamic features of 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 are discussed in detail. Triclabendazole is an intriguing case in which tautomeric and conformational variations co‐exist in the polymorphs. 相似文献