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排序方式: 共有1301条查询结果,搜索用时 15 毫秒
1.
Kota Tanaka Saki Okamura Ken Shibata Naoki Ikenaga Nobuyuki Tanaka Kazumi Hakamada Jun Miyake 《Research on Chemical Intermediates》2016,42(11):7723-7730
Renewable energy is regarded as a clean energy source but has some problems, one of which is intermittency. To reduce this, the time-delay of hydrogen production by photosynthetic bacteria can be effective. In this study, we qualitatively evaluated the time-delay of hydrogen production by photosynthetic bacteria under various irradiation conditions, and we also quantitatively evaluated it by fitting the experimental data and the hydrogen production model with a genetic algorithm. As a result of model fitting, we found that the relationship between the lengths of the optimized time-delay of hydrogen production by photosynthetic bacteria and the amount of light irradiation is linear. And we also found that the time-delay of hydrogen production by photosynthetic bacteria had an upper limit under low light intensity. We have suggested the existence of an energy store mechanism in photosynthetic bacteria. 相似文献
2.
Yoichi Makimizu Nhat Truong Nguyen Jiri Tucek Hyo-Jin Ahn JeongEun Yoo Mahshid Poornajar Imgon Hwang Stepan Kment Prof. Dr. Patrik Schmuki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(12):2685-2692
Photoelectrochemical (PEC) water splitting is a promising method for the conversion of solar energy into chemical energy stored in the form of hydrogen. Nanostructured hematite (α-Fe2O3) is one of the most attractive materials for a highly efficient charge carrier generation and collection due to its large specific surface area and the short minority carrier diffusion length. In the present work, the PEC water splitting performance of nanostructured α-Fe2O3 is investigated which was prepared by anodization followed by annealing in a low oxygen ambient (0.03 % O2 in Ar). It was found that low oxygen annealing can activate a significant PEC response of α-Fe2O3 even at a low temperature of 400 °C and provide an excellent PEC performance compared with classic air annealing. The photocurrent of the α-Fe2O3 annealed in the low oxygen at 1.5 V vs. RHE results as 0.5 mA cm−2, being 20 times higher than that of annealing in air. The obtained results show that the α-Fe2O3 annealed in low oxygen contains beneficial defects and promotes the transport of holes; it can be attributed to the improvement of conductivity due to the introduction of suitable oxygen vacancies in the α-Fe2O3. Additionally, we demonstrate the photocurrent of α-Fe2O3 annealed in low oxygen ambient can be further enhanced by Zn-Co LDH, which is a co-catalyst of oxygen evolution reaction. This indicates low oxygen annealing generates a promising method to obtain an excellent PEC water splitting performance from α-Fe2O3 photoanodes. 相似文献
3.
Prof. Yukishige Ito Prof. Yasuhiro Kajihara Prof. Yoichi Takeda 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(67):15461-15470
The introduction of Asn-linked glycans to nascent polypeptides occurs in the lumen of the endoplasmic reticulum of eukaryotic cells. After the removal of specific sugar residues, glycoproteins acquire signals in the glycoprotein quality control (GPQC) system and enter the folding cycle composed of lectin-chaperones calnexin (CNX) and calreticulin (CRT), glucosidase II (G-II), and UDP-Glc:glycoprotein glucosyltransferase (UGGT). G-II initiates glycoproteins’ entry and exit from the cycle, and UGGT serves as the “folding sensor”. This account summarizes our effort to analyze the properties of enzymes and lectins that play important roles in GPQC, especially those involved in the CNX/CRT cycle. To commence our study, general methods for the synthesis of high-mannose-type glycans and glycoproteins were established. Based on these, various substrates to analyze components of the GPQC were created, and properties of CRT, G-II, and UGGT have been clarified. 相似文献
4.
A Strategy to Control the Reactivation of Frustrated Lewis Pairs from Shelf‐Stable Carbene Borane Complexes 下载免费PDF全文
Dr. Yoichi Hoshimoto Takuya Kinoshita Prof. Dr. Masato Ohashi Prof. Dr. Sensuke Ogoshi 《Angewandte Chemie (International ed. in English)》2015,54(40):11666-11671
N‐Phosphine oxide substituted imidazolylidenes (PoxIms) have been synthesized and fully characterized. These species can undergo significant changes to the spatial environment surrounding their carbene center through rotation of the phosphine oxide moiety. Either classical Lewis adducts (CLAs) or frustrated Lewis pairs (FLPs) are thus formed with B(C6F5)3 depending on the orientation of the phosphine oxide group. A strategy to reactivate FLPs from CLAs by exploiting molecular motions that are responsive to external stimuli has therefore been developed. The reactivation conditions were successfully controlled by tuning the strain in the PoxIm–B(C6F5)3 complexes so that reactivation only occurred above ambient temperature. 相似文献
5.
6.
Matthew D. Ryan Jordan C. Theriot Chern-Hooi Lim Haishen Yang Andrew G. Lockwood Nathaniel G. Garrison Sarah R. Lincoln Charles B. Musgrave Garret M. Miyake 《Journal of polymer science. Part A, Polymer chemistry》2017,55(18):3017-3027
The nature of intramolecular charge transfer (CT) of N,N-diaryl dihydrophenazine photocatalysts (PCs) in different solvents is explored in context of their performance in organocatalyzed atom transfer radical polymerization (O-ATRP). PCs having a computationally predicted lowest energy excited state exhibiting CT character can operate a highly controlled O-ATRP in a wide range of solvent polarities, from non-polar hexanes to highly polar N,N-dimethylacetamide. For PCs having a computationally predicted lowest energy excited state not possessing CT character, their ability to operate a controlled O-ATRP is decreased. This study confirms the importance of CT character in the excited state for N,N-diaryl dihydrophenazine PCs, and a deeper understanding of the activity of CT PCs has enabled the synthesis of polymers of low dispersity (<1.10) in a controlled fashion. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3017–3027 相似文献
7.
We give a unified method to obtain the conservativeness of a class of Markov processes associated with lower bounded semi-Dirichlet forms on L 2(X;m), including symmetric diffusion processes, some non-symmetric diffusion processes and jump type Markov processes on X, where X is a locally compact separable metric space and m is a positive Radon measure on X with full topological support. Using the method, we give an example in each section, providing the conservativeness of the processes, that are given by the “increasingness of the volume of some sets(balls)” and “that of the coefficients on the sets” of the Markov processes. 相似文献
8.
Michael Andreas Tandiary Masashi Asano Taiki Hattori Satoshi Takehira Yoichi Masui Makoto Onaka 《Tetrahedron letters》2017,58(20):1925-1928
The solid acid, tin hydroxide-embedded montmorillonite, catalyzes the unprecedented alkylation of various silicon enolates with primary, secondary and tertiary benzylic alcohols as well as secondary allylic alcohols. The acid catalysis of Sn-Mont was not only higher than that of the other ion-exchanged montmorillonites (M-Mont; M = H, Ti, Fe and Al), but also higher than that of the typical homogeneous acid catalysts such as BF3·OEt2, TMSOTf and TfOH. 相似文献
9.
Ilia?NegriEmail authorView authors OrcID profile Yoichi?Nishiyama 《Statistical Inference for Stochastic Processes》2017,20(3):387-397
The problem to establish the asymptotic distribution of statistical estimators as well as the moment convergence of such estimators has been recognized as an important issue in advanced theories of statistics. This problem has been deeply studied for M-estimators for a wide range of models by many authors. The purpose of this paper is to present an alternative and apparently simple theory to derive the moment convergence of Z-estimators. In the proposed approach the cases of parameters with different rate of convergence can be treated easily and smoothly and any large deviation type inequalities necessary for the same result for M-estimators do not appear in this approach. Applications to the model of i.i.d. observation, Cox’s regression model as well as some diffusion process are discussed. 相似文献
10.
T. Suzuki T. Hatsushika M. Miyake 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4)
Abstract The cation-exchange characteristics between Pb2+ ions of aqueous solutions containing counter-anions (F?, C1?) and Ca2+ ions of synthetic hydroxyapatite samples have been investigated in detail under the conditions of low pH values (3.0, 4.0 and 5.0) by a normal batch method. Even at the low pH value of 3.0 the apatite structure in a solution containing F? or C1? ions was maintained via a concurrent ion-exchange effect of Pb2+ ions together with F? or C1?ions, which are known to be exchangeable with OH- ions of the apatite. Moreover, it was found that Ca2+ ions in the apatite sample can easily be exchanged for Pb2+ ions almost without distinction between MI and M2 sites, assisted by the loosening effect of protons even at room temperature. Next, it was found that the hydroxyapatite samples are transformed into amorphous states by the reactions between Ca 2+ ions in the samples and Sn 2+ ions in the SnC12 acidic aqueous solutions with pH of 3.0 or below with a molar ratio of Sn2+/Ca2+ -1.0. The existence of hydroxyapatite as amorphism in acidic aqueous solutions such as SnC12 is quite interesting, because in general the hydroxyapatite has been found to be dissolved in acidic aqueous solutions. Moreover, the obtained amorphism are found to be stable up to at least 500 to 6OO°C but to be unstable in alkaline solutions. The characteristics of Sn2+ ions are found to have been found to form crystalline Pb 2+ apatite even in be quite different from those of homologous Pb2+ ions which have been found to form crystalline pb2+ apatite even in such an acidic atmosphere. 相似文献