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121.
122.
S. Nasir G. Asghar Muhammad Ali Malik M. Anis-ur-Rehman 《Journal of Sol-Gel Science and Technology》2011,59(1):111-116
Zinc doped nickel ferrite nanoparticles having the general formula Ni1−xZnxFe2O4 (x = 0.1, 0.2, 0.3, 0.4, 0.5) were prepared with simplified sol–gel method. The structural and dielectric properties of these
samples sintered at 750 ± 5 °C were studied. X-ray diffraction patterns confirm the single phase spinel structure for prepared
samples. The scanning electron microscope images indicated that the particle size of the samples lies in the nanometer regime.
The dielectric constant (εr) and dielectric loss tangent (tan δ) of nanocrystalline nickel ferrites were investigated as a function of frequency and
Zn concentration. The dependence of εr and tan δ on the frequency of the alternating applied electric field is in accordance with the Maxwell–Wagner model. The
prepared samples have a lowest dielectric constant compared to the already reported samples of the same composition to the
best of our knowledge. The effect of Zn doping on the dielectric properties of nickel ferrites is explained on the basis of
cations distribution in the crystal structure. 相似文献
123.
Heterologous expression characteristics of Trichoderma viride endoglucanase V in the silkworm, Bombyx mori L 总被引:1,自引:0,他引:1
Li XH Wang MX Zhang P Hu JB Sun CG Liu XJ Zhou F Niu YS Malik FA Bhaskar R Yang HJ Miao YG 《Applied biochemistry and biotechnology》2011,165(2):728-736
Efficient degradation of cellulose needs a synergistic reaction of the cellulolytic enzymes, which include exoglucanases, endoglucanases, and β-1,4-glucosidase. In this study, we used an improved Bac-to-Bac/BmNPV baculovirus expression system, which lacks the virus-encoded chitinase cathepsin (v-cath) genes of Bombyx mori nucleopolyhedrovirus (BmNPV), to express the endoglucanase V (EG V) gene from Trichoderma viride in silkworm BmN cells and silkworm larvae, and analyzed the characteristics of the recombinant enzyme in silkworm larvae. The result showed that an around 36-kDa protein was visualized in BmN cells at 48 h after the second-generation recombinant mBacmid/BmNPV/EG V baculovirus infection. The crude enzyme extract from the recombinant baculoviruses-infected silkworms exhibited a significant maximum activity at the environmental condition of pH 5.0 and a temperature of 50 °C, and increased 39.86% and 37.76% compared with that from blank mBacmid/BmNPV baculovirus-infected silkworms and normal silkworms, respectively. It was stable at pH range from 5.0 to 10.0 and at temperature range from 40 to 60 °C. The availability of large quantities of EG V that the silkworm provides might greatly facilitate the future research and the potential application in industries. 相似文献
124.
Chuprakov S Malik JA Zibinsky M Fokin VV 《Journal of the American Chemical Society》2011,133(27):10352-10355
A highly efficient enantioselective C-H insertion of azavinyl carbenes into unactivated alkanes has been developed. These transition metal carbenes are directly generated from readily available and stable 1-sulfonyl-1,2,3-triazoles in the presence of chiral Rh(II) carboxylates and are used for C-H functionalization of alkanes to access a variety of β-chiral sulfonamides. 相似文献
125.
Malik H Kohlen W Jamil M Rutjes FP Zwanenburg B 《Organic & biomolecular chemistry》2011,9(7):2286-2293
Strigolactones are signaling compounds in plants of increasing importance. In this paper the focus is on their activity as germinating agents for seeds of parasitic weeds. The syntheses of aromatic A-ring analogues of the germination stimulant orobanchol have been described. Starting substrate is the ABC unit of the stimulant GR24. Oxidation at the C-4 position gives a 4-oxo derivative which on subsequent reduction produces two C-4 epimeric alcohols, syn and anti in a ratio of 82 : 3. For practical access of the C-4 anti alcohol, the predominant syn epimer is inverted by a Mitsunobu procedure. The anti C-4 alcohol is then coupled with the D-ring in a one-pot two-step process involving a formylation and a reaction with bromobutenolide to give a mixture of the diastereomeric aromatic A-ring analogues of orobanchol. In contrast, the syn C-4 alcohol cannot be coupled directly with the D-ring. Protection of the C-4 syn OH is a prequisite. The best protecting function is the SEM group as deprotection after coupling with the D-ring can then readily be achieved. The structures of these new analogues have been ascertained by X-ray analyses. Both diastereomers of the C-4 syn as well as the C-4 anti orobanchol analogues have been tested as germination agents of seeds of Striga hermonthica and Orobanche ramosa. In addition, the acetates of both epimeric C-4 alcohols have been prepared and tested. Both diastereomers of the 4-oxo derivative have been prepared and bioassayed as well. The bioassays reveal that the diastereomers having the natural relative configuration are most active. The data also suggest that hydrogen bonding is not an important factor in the binding of the stimulant molecules in the receptor. 相似文献
126.
In this paper, a highly selective Sudan IV molecularly imprinted polymer was synthesized by surface molecular imprinting technique in combination with a sol?Cgel process using ??-aminopropyl triethoxysilane as functional monomer, tetraethoxysilane as cross-linker and activated silica gel as support material. The imprinted polymer was characterized by FT-IR spectra, scanning electron micrograph and adsorption experiments and it was exhibited good recognition and selective ability, offered a faster rate for the adsorption of Sudan IV. Using the imprinted material as sorbent, a solid-phase extraction coupled with high-performance liquid chromatography method for determination of trace Sudan IV was presented. The detection limit (S/N = 3) was 25.2 ng L?1, and the RSD for five replicate was 2.86%. With a loading flow rate of 2.5 mL min?1 for loading 30 mL, an enrichment factor of 104 was achieved. This method was applied for extraction and determination of chilli powder and duck egg samples with good recoveries ranging from 85.3 to 98.1%. 相似文献
127.
Caragisides A–C ( 1 – 3 , resp.), three new isoflavone glucosides, were isolated from the BuOH sub‐fraction of the EtOH extract of the whole plant of Caragana conferta, along with ononoside ( 4 ), reported for the first time from this species. The structures of the new compounds were elucidated by spectroscopic techniques including MS and 2D‐NMR spectroscopy. Compounds 1 – 3 showed significant inhibition of platelet aggregation. 相似文献
128.
Sukul PK Asthana D Mukhopadhyay P Summa D Muccioli L Zannoni C Beljonne D Rowan AE Malik S 《Chemical communications (Cambridge, England)》2011,47(43):11858-11860
We report unique and spontaneous formation of hydrogels of perylene derivatives with melamine. The luminescent gel network is formed by H-type aggregation of the perylene core, supramolecularly cross-linked by melamine units. As a result of controlled aggregation in the extended nanofibers, strong exciton fluorescence emission is observed. 相似文献
129.
Lemasson F Tittmann J Hennrich F Stürzl N Malik S Kappes MM Mayor M 《Chemical communications (Cambridge, England)》2011,47(26):7428-7430
Photocleavable polymers based on 9,9-dialkylfluorene backbone and o-nitrobenzylether were designed and synthesized to obtain stable (n,m) enriched suspensions of semiconducting SWNTs in toluene. Photoirradiation of the suspensions triggered the precipitation of the SWNTs and TEM images indicate close packing of SWNTs pointing at partial removal of the coating polymer. 相似文献
130.
Akhtar J Mehmood RF Malik MA Iqbal N O'Brien P Raftery J 《Chemical communications (Cambridge, England)》2011,47(6):1899-1901
We describe for the first time the use of a single source precursor to deposit thin films and nanocrystals of palladium selenide. 相似文献