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21.
Acyl phosphonates with alpha-halo ketones in the presence of bases at room temperature afford cis- and trans-epoxyphosphonates in good chemical yields and high selectivities using different bases. The diastereoselectivity of this reaction is easily controlled by changing the base. Changing the base from Cs2CO3 to DBU changed the diastereomeric ratio (trans/cis) from 3/2 to 9/1. Moreover, the treatment of the trans isomer with DBU showed a complete conversion to the corresponding cis isomer. 相似文献
22.
Eser S. Akturk Dr. Glenn P. A. Yap Prof. Dr. Klaus H. Theopold 《Angewandte Chemie (International ed. in English)》2015,54(49):14974-14977
A chromium(I) dinitrogen complex reacts rapidly with O2 to form the mononuclear dioxo complex [TptBu,MeCrV(O)2] (TptBu,Me=hydrotris(3‐tert‐butyl‐5‐methylpyrazolyl)borate), whereas the analogous reaction with sulfur stops at the persulfido complex [TptBu,MeCrIII(S2)]. The transformation of the putative peroxo intermediate [TptBu,MeCrIII(O2)] (S=3/2) into [TptBu,MeCrV(O)2] (S=1/2) is spin‐forbidden. The minimum‐energy crossing point for the two potential energy surfaces has been identified. Although the dinuclear complex [(TptBu,MeCr)2(μ‐O)2] exists, mechanistic experiments suggest that O2 activation occurs on a single metal center, by an oxidative addition on the quartet surface followed by crossover to the doublet surface. 相似文献
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24.
2-Hydroxy-2,2-diphenylacetohydrazide (2), cyclic ketones, and mercaptoalkanoic acids were converted into 2-hydroxy-N-(3-oxo-1-thia-4-azaspiro[4.4]non/[4.5]dec-4-yl)-2,2-diphenylacetamide derivatives (3, 4) in a one pot procedure. Compounds 3 and 4 were tested for in vitro antimycobacterial activity against M. tuberculosis H37Rv. The compounds were found to provide 0–86% inhibition of mycobacterial growth in the primary screen conducted at 6.25 μg/cm3. 相似文献
25.
Asymptotic Iteration Method for Energies of Inversely Linear Potential with Spatially Dependent Mass
The bound-state solution of the position dependent mass Klein-Gordon equation including inversely linear potential is obtained within the framework of the asymptotic iteration method. The relation between the scalar and vector potentials is considered to S(x) = V(x)(β - 1). In particular, it is shown that the corresponding method exactly reproduces the spectrum of linearly inversely potentials with spatially dependent mass. 相似文献
26.
We analyze the tradeoff between efficiency and service quality in tandem systems with flexible servers and finite buffers. We reward efficiency by assuming that a revenue is earned each time a job is completed, and penalize poor service quality by incorporating positive holding costs. We study the dynamic assignment of servers to tasks with the objective of maximizing the long-run average profit. For systems of arbitrary size, structured service rates, and linear or nonlinear holding costs, we determine the server assignment policy that maximizes the profit. For systems with two stations, two servers with arbitrary service rates, and linear holding costs, we show that the optimal server assignment policy is of threshold type and determine the value of this threshold as a function of the revenue and holding cost. The threshold can be interpreted as the best possible buffer size, and hence our results prove the equivalence of addressing service quality via a holding cost and via limiting the buffer size. Furthermore, we identify the optimal buffer size when each buffer space comes at a cost. We provide numerical results that suggest that the optimal policy also has a threshold structure for nonlinear holding costs. Finally, for larger systems with arbitrary service rates, we propose effective server assignment heuristics. 相似文献
27.
?i?dem???hedef Serap?Teks?zEmail author Kamile??enocak Eser?U?ar Ayfer?Yurt?K?l?ar 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(3):845-849
The aim of this study is to prepare radiolabeled guanine with 99mTc(CO)3+ core. For this purpose, guanine has been radiolabeled with 99mTc(CO)3+ core. Quality control study of radiolabeled guanine molecule with 99mTc(CO)3+ core was performed by thin layer radio chromatography (TLRC) and high performance liquid radio chromatography (HPLRC). The
results showed that the radiolabeling yield was quite high (94 ± 3%). Beside that 99mTc(CO)3–Gua complex has showed good in vitro stability during the 24 h period. Radiopharmaceutical potential of this complex was
evaluated in Wistar Albino Rats. It was concluded that 99mTc(CO)3–Gua could be used as a nucleotide radiopharmaceutical for in vivo applications. 相似文献
28.
Half-metallic ferrimagnetism in the Ti2CoAl Heusler compound 总被引:1,自引:0,他引:1
Eser BayarNazmiye Kervan Selçuk Kervan 《Journal of magnetism and magnetic materials》2011,323(23):2945-2948
Density functional calculations performed on the Ti2CoAl Heusler compound confirm it to be a half-metallic ferrimagnet with the spin-down energy gap of 0.49 eV. The Ti2CoAl Heusler compound has a magnetic moment of 2 μB at the equilibrium lattice constant a=6.14 Å. The Ti2CoAl Heusler compound is ferrimagnetic and maintains the half-metallic character having 100% polarization for lattice constants ranging between 5.85 and 6.44 Å. 相似文献
29.
In this paper, a novel method degrading the combined effect of four-wave mixing (FWM) and amplified spontaneous emission (ASE) noise of the amplifier on the most heavily affected channel in an equally channel spaced wavelength division multiplexing (WDM) system containing in-line optical amplifiers is proposed. FWM effect is directly related to input powers of channels. So, FWM effect can be degraded by controlling channel input powers. In the proposed method, varying the input power of each channel in an optical fiber, the output optical signal to noise ratio (OSNR) values are evaluated and input powers of all channels are optimized in order to maximize the OSNR value of the channel having the lowest OSNR. To interpret the results obtained, output OSNR values for the minimum optical input power launched to the system by each channel are also computed. Being compared to the computed results for minimum optical input powers, the lowest output OSNR value among all channels for optimized input powers shows a 5.1867 dB increase in a 5-channel system, a 3.5988 dB increase in a 9-channel system, a 3.0855 dB increase in a 15-channel system and a 1.6795 dB increase for a 21-channel system. Furthermore, output OSNR values of all channels exhibit a significant increase. 相似文献
30.
Lars-Erik Meyer Bekir Engin Eser Selin Kara 《Current Opinion in Green and Sustainable Chemistry》2021
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