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51.
Nagata M Kondo M Suemori Y Ochiai T Dewa T Ohtsuka T Nango M 《Colloids and surfaces. B, Biointerfaces》2008,64(1):16-21
Dialkyl disulfide-linked naphthoquinone, (NQ-Cn-S)2, and anthraquinone, (AQ-Cn-S)2, derivatives with different spacer alkyl chains (Cn: n = 2, 6, 12) were synthesized and these quinone derivatives were self-assembled on a gold electrode. The formation of self-assembled monolayers (SAMs) of these derivatives on a gold electrode was confirmed by infrared reflection-absorption spectroscopy (IR-RAS). Electron transfer between the derivatives and the gold electrode was studied by cyclic voltammetry. On the cyclic voltammogram a reversible redox reaction between quinone (Q) and hydroquinone (QH2) was clearly observed under an aqueous condition. The formal potentials for NQ and AQ derivatives were −0.48 and −0.58 V, respectively, that did not depend on the spacer length. The oxidation and reduction peak currents were strongly dependent on the spacer alkyl chain length. The redox behavior of quinone derivatives depended on the pH condition of the buffer solution. The pH dependence was in agreement with a theoretical value of E1/2 (mV) = E′ − 59pH for 2H+/2e− process in the pH range 3–11. In the range higher than pH 11, the value was estimated with E1/2 (mV) = E′ − 30pH , which may correspond to H+/2e− process. The tunneling barrier coefficients (β) for NQ and AQ SAMs were determined to be 0.12 and 0.73 per methylene group (CH2), respectively. Comparison of the structures and the alkyl chain length of quinones derivatives on these electron transfers on the electrode is made. 相似文献
52.
Cyclopolymerization of a bis-methacrylate monomer derived from trans-cyclohexanediol and 2-methacryloyloxyethyl isocyanate proceeded through 19-membered ring formation. The unusual large ring formation originated from the designed steric regulation by the cyclohexane ring and the hydrogen bonds. The RAFT polymerization employing cumyl dithiobenzoate attained controlled polymerization, which supported the quantitative cyclization. 相似文献
53.
A Tin Analogue of Carbenoid: Isolation and Reactivity of a Lithium Bis(imidazolin‐2‐imino)stannylenoid 下载免费PDF全文
Tatsumi Ochiai Dr. Daniel Franz Dr. Xiao‐Nan Wu Dr. Elisabeth Irran Prof. Dr. Shigeyoshi Inoue 《Angewandte Chemie (International ed. in English)》2016,55(24):6983-6987
The lithium bis(imino)stannylenoid (NIPr)2Sn(Li)Cl ( 1 ; NIPr=bis(2,6‐diisopropylphenyl)imidazolin‐2‐imino) was prepared by the reaction of LiNIPr with 0.5 equiv of SnCl2?diox (diox=1,4‐dioxane) and the ambiphilic character of the compound was demonstrated by investigations into its reactivity. Treatment of 1 with I2 or MeI yielded the oxidative addition products (NIPr)2SnI2 and (NIPr)2Sn(Me)I, respectively. In contrast, the reaction of 1 with one equivalent of Me3SiCl resulted in the formation of Me3SiNIPr and the chlorostannylene dimer [NIPrSnCl]2. Moreover, the substitution reaction of compound 1 with MeLi led to the formation of the methyl‐substituted stannate (NIPr)2Sn(Li)Me. 相似文献
54.
4-(Difluoroiodo)toluene-induced domino lambda(3)-iodanation-1,4-halogen shift-ring enlargement-fluorination reaction of 5-halopentynes with a four-, five-, or six-membered carbocycle afforded the ring-expanded (E)-delta-fluoro-beta-halovinyl-lambda3-iodanes stereoselectively in high yields, probably via the intermediacy of five-membered halonium ions. Use of internal alkynes makes it possible to synthesize tetrasubstituted beta-halovinyl-lambda(3)-iodanes with defined stereochemistry. 相似文献
55.
In this work, we first formulate the Tsallis entropy in the context of complex networks. We then propose a network construction whose topology maximizes the Tsallis entropy. The growing network model has two main ingredients: copy process and random attachment mechanism (C-R model). We show that the resulting degree distribution exactly agrees with the required degree distribution that maximizes the Tsallis entropy. We also provide another example of network model using a combination of preferential and random attachment mechanisms (P-R model) and compare it with the distribution of the Tsallis entropy. In this case, we show that by adequately identifying the exponent factor q, the degree distribution can also be written in the q-exponential form. Taken together, our findings suggest that both mechanisms, copy process and preferential attachment, play a key role for the realization of networks with maximum Tsallis entropy. Finally, we discuss the interpretation of q parameter of the Tsallis entropy in the context of complex networks. 相似文献
56.
T. Nojima K. Takahashi M. Chotoku A. Ochiai H. Aoki H.-G. Lee S.-I. Lee 《Physica C: Superconductivity and its Applications》2009,469(15-20):1055-1058
We have studied the order–disorder transition in high quality MgB2 single crystals, using a torque magnetometry combined with a ‘vortex shaking’ technique. In the wide range of temperature T, field H and the H direction, we succeed in obtaining reversible magnetization curves Mrev(T, H) by shaking the pinned vortices. Especially at low temperatures below 25 K and high fields, where the irreversible magnetization curve exhibits the peak effect due to the order–disorder transition, it is found that the peak is transformed into the clear step in Mrev(H). Similar step-like behavior is also observed in the temperature dependence of magnetization Mrev(T). These results give direct evidence that the order–disorder transition, which is hidden by the large hysteresis of magnetization, has the nature of first-order transition. 相似文献
57.
Kazuaki Sakoda Takashi Kuroda NaokiI keda Takaaki Mano Yoshimasa Sugimoto Tetsuyuki Ochiai Keiji Kuroda Shunsuke Ohkouchi Nobuyuki Koguchi Kiyoshi Asakawa 《中国光学快报(英文版)》2009,7(10):879-881
We fabricate photonic crystal slab microcavities embedded with GaAs quantum dots by electron beam lithography and droplet epitaxy. The Purcell effect of exciton emission of the quantum dots is confirmed by the micro photoluminescence measurement. The resonance wavelengths, widths, and polarization are consistent with numerical simulation results. 相似文献
58.
Chiba J Iimura S Yoneda Y Sugimoto Y Horiuchi T Muro F Ochiai Y Ogasawara T Tsubokawa M Iigou Y Takayama G Taira T Takata Y Yokoyama M Takashi T Nakayama A Machinaga N 《Chemical & pharmaceutical bulletin》2006,54(11):1515-1529
A novel series of benzoic acid derivatives as VLA-4 antagonists were synthesized. Optimization, focusing on activity and lipophilicity needed for cell permeability, resulted in the identification of 15b and 15e with good activity (IC50 = 1.6 nM each) and moderate lipophilicity (Log D = 2.0, 1.8). Furthermore, 15e demonstrated efficacy in murine asthma model by an oral dose of 30 mg/kg. 相似文献
59.
A method for fast screening of pesticide multiresidues in aqueous samples using dual stir bar sorptive extraction-thermal desorption-low thermal mass gas chromatography-mass spectrometry (dual SBSE-TD-LTM-GC-MS) has been developed. Recovery of 82 pesticides - organochlorine, carbamate, organophosphorous, pyrethroid and others - for the SBSE was evaluated as a function of octanol-water distribution coefficients (logK(o/w): 1.7-8.35), sample volume (2-20mL), salt addition (0-30% NaCl), and methanol addition (0-20%). The optimized method consists of a dual SBSE performed simultaneously on respectively a 20-mL sample containing 30% NaCl and a 20-mL sample without modifier (100% sample solution). One extraction with 30% NaCl is mainly targeting solutes with low K(o/w) (logK(o/w)<3.5) and another extraction with unmodified sample solution is targeting solutes with medium and high K(o/w) (logK(o/w)>3.5). After extraction, the two stir bars are placed in a single glass desorption liner and are simultaneously desorbed. The desorbed compounds are analyzed by use of LTM-GC-MS with fast temperature programming (75 degrees Cmin(-1)) using a 0.18mm i.d. narrow-bore capillary column and fast scanning (10.83 scan s(-1)) using quadrupole MS. The method showed good linearity (r(2)>0.9900) and high sensitivity (limit of detection: <10ngL(-1)) for most of the target pesticides. The method was applied to the determination of pesticides at nanograms per liter levels in river water and brewed green tea. 相似文献
60.
Ochiai M Tada N Murai K Goto S Shiro M 《Journal of the American Chemical Society》2006,128(30):9608-9609
Stable aliphatic bromonium ylides (RfSO2)2C--Br+C6H4-p-CF3 (Rf = CF3, CF3(CF2)3) have been synthesized and structurally characterized for the first time. X-ray crystallographic analyses indicated a ylide structure with an sp2 hybridization of the ylide carbanions and with little double-bond character for the ylidic bond. The bromonium ylides selectively undergo transfer of the aryl group to nitrogen heterocycles, such as pyridines, yielding N-arylpyridinium salts. This is in a marked contrast to the reaction of the iodonium ylides, which produces pyridinium ylides through transylidations. 相似文献