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91.
Michael P. Curtis William H. Bunnelle Thomas G. Pagano Murali Gopalakrishnan 《合成通讯》2013,43(3):321-326
Small heterocyclic amines such as 1,3‐diaza‐bicyclo[3.2.2]nonane are known to be key components of biologically active molecules. A convenient synthesis of this compound utilizing a key Beckmann rearrangement of (Z)‐1‐aza‐bicyclo[2.2.2]octan‐3‐one oxime (6) with conc. H2SO4 under microwave irradiation was achieved. The desired compound (1) was obtained in 20% yield overall. 相似文献
92.
S. Priya R. K. Gopalakrishnan A. Goswami 《Journal of Radioanalytical and Nuclear Chemistry》2014,302(1):353-359
The commercial Hidex LSC system has been used to measure triple to double coincidence ratio (TDCR), experimental counting efficiency (CE) and the absolute activity for radioactive standards of pure beta emitters viz. 3H, 63Ni and 55Fe, an electron capture nuclide. Colour and chemical quench measurements of 63Ni and 55Fe have been done. An excellent match between TDCR and CE has been obtained for beta emitters, while very large deviations have been observed for 55Fe. The deviation between TDCR and experimental efficiency has been found to be nearly uniform. Based on this, an empirical correction factor for TDCR which gives the correct efficiency has been evaluated, to enable efficient application of this commercial instrument for 55Fe estimation. These TDCR correction factors were further validated by applying for 55Fe activity measurements in ASTM standard steel samples irradiated to a fixed neutron flux in research reactor CIRUS. Finally, 55Fe activity in steel sample from APSARA reactor decommissioning waste was successfully estimated using this modified TDCR. 相似文献
93.
Reshma V. R. Nair Devi Velayudhan Jayasree Prabath Gopalakrishnan Biju 《Natural product research》2020,34(16):2319-2322
Abstract Humboldtia unijuga Bedd., endemic to Agasthyamala in Western Ghats in India, is traditionally used by local Kani tribes for chicken pox, head ache and snake bite. This study reports the isolation of erythrodiol-3-acetate (HU-1) and 2,4-di-tert-butylphenol (HU-2) from H. unijuga roots and their anti-inflammatory and anticancer activities in macrophage, skin and breast cancer cell lines. Effects of HU-1 and HU-2 treatments (50, 100?µg/mL) on gene expression profiles of pro-inflammatory cytokines TNFα, IL-6 and IL-1β, and apoptosis genes p53 and caspase 7 were studied. HU-2 exerted a significantly superior anti-inflammatory effect compared to HU-1 in all three pro-inflammatory genes. HU-2 showed a superior dose dependent anticancer effect through activation of p53 gene over HU-1 in MCF-7 cells. HU-1 exhibited a dose dependent effect on caspase 7 gene in both cell lines while HU-2 was more effective in A431. HU-2 has potential for development as a novel anti-inflammatory and anticancer agent. 相似文献
94.
It is shown that by adopting a very gradual programmed cooling procedure in oxygen environment one can obtain a sharp transition
(ΔT
c⋍1 K) in YBa2Cu3O7−x
while retaining the high-T
c value (⋍105 K) of samples prepared by a semi-wet route. This is attributed to a maximum occupancy of oxygen at 0 1/2 0 sites
and a near-perfect ordering of vacancies at 1/2 0 0 sites in the orthorhombic unit cell which maximizes the availability of
conduction paths in the form of continuous CuO4 chains. Critical current densities (J
c) of 204 A cm−2 are obtained for bulk samples at 77 K. It is suggested that the intergrain coupling is weak and thus limits the transportJ
c-values. 相似文献
95.
R. A. Gunasekaran I. K. Gopalakrishnan J. V. Yakhmi R. M. Iyer
C. V. Tomy
S. K. Malik 《Physica C: Superconductivity and its Applications》1991,180(5-6):324-330Superconducting behaviour of the tetragonal superconductor CaBaLaCu3O7−δ (Tc = 70 K) has been studied as a function of substitution of Ni and Zn for Cu. Both electrical resistivity and AC susceptibility measurements show that Tc decreases monotonically with increasing concentration of the substituent ion, within the composition range where the samples remain single phase, although Zn suppresses Tc more strongly than Ni for equivalent concentrations. It is argued that the suppression of Tc in this system cannot be explained by the Abrikosov-Gorkov mechanism alone. 相似文献
96.
Aravindan A Srinivasan P Vijayan N Gopalakrishnan R Ramasamy P 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,71(2):297-304
A comparative study on the properties of L-alanine and LAAN crystals has been made and discussed. It may be concluded that the protonation of the amino group in the L-alanine molecule is the key factor in increasing the relative SHG efficiency of LAAN. The protonation is justified by the crystal structure analysis, FTIR and photoluminescence studies. The factor group vibrations are compared and found that there is an increase in vibrational modes of LA when reacted with nitric acid forming LAAN. 相似文献
97.
Edison Thomas Nesakumar Jebakumar Immanuel Sethuraman Mathur Gopalakrishnan Lee Yong Rok 《Research on Chemical Intermediates》2016,42(2):713-724
Research on Chemical Intermediates - This study deals with reduction of ortho and para-nitroaniline by NaBH4 with silver nanoparticles (AgNPs), synthesized by use of a green method, as catalyst. In... 相似文献
98.
Developing Intense Blue and Magenta Colors in α‐LiZnBO3: The Role of 3d‐Metal Substitution and Coordination 下载免费PDF全文
S. Tamilarasan Prof. Dr. M. L. P. Reddy Prof. Dr. S. Natarajan Prof. Dr. J. Gopalakrishnan 《化学:亚洲杂志》2016,11(22):3234-3240
We describe the synthesis, crystal structures, and optical absorption spectra/colors of 3d‐transition‐metal‐substituted α‐LiZnBO3 derivatives: α‐LiZn1?xMIIxBO3 (MII=CoII (0<x<0.50), NiII (0<x≤0.05), CuII (0<x≤0.10)) and α‐Li1+xZn1?2xMIIIxBO3 (MIII=MnIII (0<x≤0.10), FeIII (0<x≤0.25)). The crystal structure of the host α‐LiZnBO3, which is both disordered and distorted with respect to Li and Zn occupancies and coordination geometries, is largely retained in the derivatives, which gives rise to unique colors (blue for CoII, magenta for NiII, violet for CuII) that could be of significance for the development of new, inexpensive, and environmentally friendly pigment materials, particularly in the case of the blue pigments. Accordingly, this work identifies distorted tetrahedral MO4 (M=Co, Ni, Cu) structural units, with a long M?O bond that results in trigonal bipyramidal geometry, as new chromophores for blue, magenta, and violet colors in a α‐LiZnBO3 host. From the L*a*b* color coordinates, we found that Co‐substituted compounds have an intense blue color that is stronger than that of CoAl2O4 and YIn0.90Mn0.10O3. The near‐infrared (NIR) reflectance spectral studies indicate that these compounds exhibit a moderate IR reflectivity that could be significant for applications as “cool pigments”. 相似文献
99.
We describe an investigation of Ba3MIIMIVWO9 oxides for MII = Ca, Zn, and other divalent metals and MIV = Ti, Zr. In general, a 1:2-ordered 6H (hexagonal, P63/mmc) perovskite structure is stabilized at high temperatures (1300 degrees C) for all of the Ba3MIITiWO9 oxides investigated. An intermediate phase possessing a partially ordered 1:1 double perovskite (3C) structure with the cation distribution, Ba2(Zn2/3Ti1/3)(W2/3Ti1/3)O6, is obtained at 1200 degrees C for Ba3ZnTiWO9. Sr substitution for Ba in the latter stabilizes the cubic 3C structure instead of the 6H structure. A metastable Ba3CaZrWO9 that adopts the 3C (cubic, Fmm) structure has also been synthesized by a low-temperature metathesis route. Besides yielding several new perovskite oxides that may be useful as dielectric ceramics, the present investigation provides new insights into the complex interplay of crystal chemistry (tolerance factor) and chemical bonding (anion polarization and d0-induced distortion of metal-oxygen octahedra) in the stabilization of 6H versus 3C perovskite structures for the Ba3MIIMIVWO9 series. 相似文献
100.
Narayanan MC Rao PR Shanmugam NN Gopalakrishnan SM Devi K 《Natural product research》2007,21(10):903-909
The roots of Dalbergia horrida yielded two new isoflavanones, Dalhorridin (I) - 5,5'-dihydroxy-3',4'-methylenedioxy-5'-prenyl-6',6'-dimethyl-dihydropyrano(2',3' : 7,8)-isoflavanone and Dalhorridinin (II) - 5,7,5'-trihydroxy-3',4'-methylenedioxy-8-[5-methyl-2-(2-hydroxyisopropyl)-1,4-hexadienyl]isoflavanone along with two known isoflavones, Dalspinin and Dalspinosin. Preliminary biological screening of the enriched extract revealed that it showed analgesic, anti-inflammatory, CNS depressant and mild anti-bacterial properties. 相似文献