排序方式: 共有47条查询结果,搜索用时 15 毫秒
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Murat Aydemir Nermin Meric Akin Baysal Yilmaz Turgut Cezmi Kayan Sevil ?eker Mahmut To?rul Bahattin Gümgüm 《Journal of organometallic chemistry》2011,696(8):1541-1546
Enantioselective reduction of prochiral ketones to optically active secondary alcohols is an important subject in synthetic organic chemistry because the resulting chiral alcohols are extremely useful, biologically active compounds. The new chiral ligands (2R)-2-[benzyl{(2-((diphenylphosphanyl)oxy)ethyl)}amino]butyldiphenylphosphinite, 1 and (2R)-2-[benzyl{(2-((dicyclohexylphosphanyl)oxy)ethyl)}amino]butyldicyclohexylphosphinite, 2 and the corresponding ruthenium(II) complexes 3 and 4 have been prepared. The structures of these complexes have been elucidated by a combination of multinuclear NMR spectroscopy, IR spectroscopy and elemental analysis. 31P-{1H} NMR, DEPT, 1H-13C HETCOR or 1H-1H COSY correlation experiments were used to confirm the spectral assignments. These ruthenium(II)-phosphinite complexes have been used as catalysts for the asymmetric transfer hydrogenation of acetophenone derivatives. Under optimized conditions, aromatic ketones were reduced in good conversions and in moderate to good enantioselectivities (up to 85% ee). 相似文献
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Nilhan Kayaman Apohan Sevim Karataş Buket Bilen Atilla Güngör 《Journal of Sol-Gel Science and Technology》2008,46(1):87-97
A series of UV-curable nanocomposite coating materials were prepared by sol–gel technique from tetraethoxysilane (TEOS), methacryloxypropyltrimethoxysilane
(MAPTMS) in the presence of urethane acrylate resin based on polyethylene glycol 400 (PEG400). The sol–gel precursor content
in the hybrid coatings was varied from 0 to 30 wt.%. In addition, acrylated phenylphosphine oxide oligomer (APPO) is replaced
with urethane acrylate resin in order to investigate its effect on the nanocomposite property. The physical and mechanical
properties such as; gel content, hardness, adhesion, gloss, impact strength as well as tensile strength were examined. Results
from these measurements showed that all the properties of the hybrid coatings improved effectively by gradual increase in
sol–gel precursor and APPO resin content. The real time infrared technique was used to follow the degree of acrylic double
bond conversion. The thermal stabilities of the UV-cured nanocomposites were investigated by thermogravimetric analysis. The
results revealed that the addition of sol–gel precursor and APPO oligomer into the organic network leads to an improvement
in the thermal and flame resistance properties of the hybrid materials. It was also determined that the APPO containing hybrid
coating with 20 wt.% silica content gave higher char yield than the coating without APPO. It is a desirable achievement to
improve simultaneously both the flame retardancy and mechanical properties of a protective coating. SEM studies indicated
that inorganic particles were dispersed homogenously through the organic matrix. The hybrids were nanocomposite. It was also
found that, incorporation of APPO resin might govern the silica organization and this leading to formation of nanofibrillar
structure. 相似文献
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Molecular Recognition of the Hybrid‐2 Human Telomeric G‐Quadruplex by Epiberberine: Insights into Conversion of Telomeric G‐Quadruplex Structures
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Dr. Clement Lin Guanhui Wu Dr. Kaibo Wang Dr. Buket Onel Dr. Saburo Sakai Prof. Yong Shao Prof. Danzhou Yang 《Angewandte Chemie (International ed. in English)》2018,57(34):10888-10893
Human telomeres can form DNA G‐quadruplex (G4), an attractive target for anticancer drugs. Human telomeric G4s bear inherent structure polymorphism, challenging for understanding specific recognition by ligands or proteins. Protoberberines are medicinal natural‐products known to stabilize telomeric G4s and inhibit telomerase. Here we report epiberberine (EPI) specifically recognizes the hybrid‐2 telomeric G4 predominant in physiologically relevant K+ solution and converts other telomeric G4 forms to hybrid‐2, the first such example reported. Our NMR structure in K+ solution shows EPI binding induces extensive rearrangement of the previously disordered 5′‐flanking and loop segments to form an unprecedented four‐layer binding pocket specific to the hybrid‐2 telomeric G4; EPI recruits the (?1) adenine to form a “quasi‐triad” intercalated between the external tetrad and a T:T:A triad, capped by a T:T base pair. Our study provides structural basis for small‐molecule drug design targeting the human telomeric G4. 相似文献
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Ozsoz M Erdem A Ozkan D Kara P Karadeniz H Meric B Kerman K Girousi S 《Bioelectrochemistry (Amsterdam, Netherlands)》2005,67(2):199-203
Electrochemical DNA biosensors have become strong candidates for DNA based analysis. Allele-specific genotyping is also one of the important research areas, where electrochemical approaches provide promising advances. Recently reported two methods based on electrochemical guanine and colloidal gold (Au) nanoparticle oxidation signals are reviewed and compared with the existing genotyping methods in this report. 相似文献
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Kara P Cavdar S Meric B Erensoy S Ozsoz M 《Bioelectrochemistry (Amsterdam, Netherlands)》2007,71(2):204-210
Direct electrochemical genosensor was developed for the detection of a probe sequence relative position in a PCR amplicon for the optimum detection of bacterial and microbiological diseases, in this study. The genosensor relies on a label-free electrochemical detection. The amino-linked inosine modified (guanine-free) coequal capture probes which were chosen from different parts of a PCR amplicon, immobilized on to disposable pencil graphite electrodes (PGE) by electrostatically and covalently. As a model case Hepatitis B virus (HBV) genome amplicon was used for the detection and specification. Hybridization was occurred after surface coverage with denatured amplicons. After hybridization, optimum probe sequence position was identified by using the differences between the responses of guanine oxidation signals. The results of this study might have a great convenience for the microbiological diseases detection applications such as DNA micro arrays. 相似文献
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A strategy for the detection of anthrax, which is a potential biological weapon by using an electrochemical genosensing technology, is investigated. An alkanathiol‐linked or unlabeled capture probe related to B. anthracis is immobilized onto gold or graphite electrode surface. A 101‐mer anthrax target is used for hybridization. The extent of hybridization between probe and target sequences is determined by using differential pulse voltammetry (DPV) and electrochemical impedance spectrometry (EIS). EIS analysis are based on electron transfer resistance (Rct) in the presence of [Fe(CN)6]3?/4? and DPV measurements are based on transduction of both guanine oxidation and Meldola's blue (MDB) reduction signal as hybridization indicator. The response of the probe‐modified electrodes which was interacted with a noncomplementary sequence was the same as the responses of probe‐modified surface and proved the specifity of the hybridization with the target. According to these results the developed genosensors based on EIS and DPV techniques can be employed for rapid and selective detection of B. anthracis. 相似文献
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Fatma Meydaneri Buket Saatçi Mehmet Gündüz Mehmet Özdemir 《Continuum Mechanics and Thermodynamics》2013,25(6):691-704
The variations of thermal conductivities of solid phases versus temperature for pure Sn, pure Zn and Sn–9 wt.% Zn, Sn–14 wt.% Zn, Sn–50 wt.% Zn, Sn–80 wt.% Zn binary alloys were measured with a radial heat flow apparatus. The thermal conductivity ratios of liquid phase to solid phase for the pure Sn, pure Zn and eutectic Sn–9 wt.% Zn alloy at their melting temperature are found with a Bridgman-type directional solidification apparatus. Thus, the thermal conductivities of liquid phases for pure Sn, pure Zn and eutectic Sn–9 wt.% Zn binary alloy at their melting temperature were evaluated by using the values of solid phase thermal conductivities and the thermal conductivity ratios of liquid phase to solid phase. 相似文献
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Ultrasonic degradation, mineralization and detoxification of diclofenac in water: Optimization of operating parameters 总被引:2,自引:0,他引:2
V. Naddeo V. Belgiorno D. Kassinos D. Mantzavinos S. Meric 《Ultrasonics sonochemistry》2010,17(1):179-185
The 20 kHz ultrasound-induced degradation of non-steroidal, anti-inflammatory drug diclofenac (DCF) was investigated. Several operating conditions, such as power density (25–100 W/L), substrate concentration (2.5–80 mg/L), initial solution pH (3.5–11), liquid bulk temperature and the type of sparging gas (air, oxygen, argon), were tested concerning their effect on DCF degradation (as assessed measuring absorbance at 276 nm) and hydroxyl radicals generation (as assessed measuring H2O2 concentration). Sample mineralization (in terms of TOC and COD removal), aerobic biodegradability (as assessed by the BOD5/COD ratio) and ecotoxicity to Daphnia magna and Artemia salina were followed too.DCF conversion is enhanced at increased applied power densities and liquid bulk temperatures, acidic conditions and in the presence of dissolved air or oxygen. The reaction rate increases with increasing DCF concentration in the range 2.5–5 mg/L but it remains constant in the range 40–80 mg/L, indicating different kinetic regimes (i.e. first and zero order, respectively). H2O2 production rates in pure water are higher than those in DCF solutions, implying that decomposition basically proceeds through hydroxyl radical reactions. Mineralization is a slow process as reaction by-products are more stable than DCF to total oxidation; nonetheless, they are also more readily biodegradable. Toxicity to D. magna increases during the early stages of the reaction and then decreases progressively upon degradation of reaction by-products; nevertheless, complete toxicity elimination cannot be achieved at the conditions in question. Neither the original nor the treated DCF samples are toxic to A. salina. 相似文献
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