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排序方式: 共有370条查询结果,搜索用时 15 毫秒
291.
In this study, the immobilization characteristics of Enterococcus faecalis RKY1 for succinate production were examined. At first, three natural polymers—agar, κ-carrageenan, and sodium alginate—were
tried as immobilizing matrices. Among these, sodium alginate was selected as the best gel for immobilization of E. faecalis RKY1. Efficient conditions for immobilization were established to be with a 2% (w/v) sodium alginate solution and 2-mm-diameter
bead. The bioconversion characteristics of the immobilized cellsat various pH values and temperatures were examined and compared
with those of free cells. The optimum pH and temperature of the immobilized cells were the same as for free cells, 7.0 and
38°C respectively, but the conversion ratio was higher by immobilization for all the other pH and temperature conditions tested.
When the seed volume of the immobilized cells was adjusted to 10% (v/v), 30 g/L of fumarate was completely converted tosuccinate
(0.973 g/g conversion ratio) after 12 h. In addition, the immobilized cells maintained a conversion ratio of >0.95 g/g during
4wk of storageat 4°C in a 2% (w/v) CaCl2 solution. In repetitive bioconversion experiments, the activity of the immobilized cells decreased linearly according to
the number of times of reuse. 相似文献
292.
Summary: A novel experimental set‐up has been devised to measure simultaneously, in real time, the conversion and shrinkage of multi‐acrylates during photopolymerization. The data show that the current practice of assigning the excess volume entirely as excess free volume is inappropriate as this leads to an increasing fractional free volume with conversion. We propose to partition the excess volume into free and occupied volume components. The new model produces satisfactory results.
293.
Siin Kim Jungkweon Choi Dae Won Cho Mina Ahn Seunghwan Eom Jungmin Kim Kyung-Ryang Wee Hyotcherl Ihee 《Chemical science》2022,13(13):3809
Proton-coupled electron transfer (PCET), an essential process in nature with a well-known example of photosynthesis, has recently been employed in metal complexes to improve the energy conversion efficiency; however, a profound understanding of the mechanism of PCET in metal complexes is still lacking. In this study, we synthesized cyclometalated Ir complexes strategically designed to exploit the excited-state intramolecular proton transfer (ESIPT) of the ancillary ligand and studied their photoinduced PCET in both aprotic and protic solvent environments using femtosecond transient absorption spectroscopy and density functional theory (DFT) and time-dependent DFT calculations. The data reveal solvent-modulated PCET, where charge transfer follows proton transfer in an aprotic solvent and the temporal order of charge transfer and proton transfer is reversed in a protic solvent. In the former case, ESIPT from the enol form to the keto form, which precedes the charge transfer from Ir to the ESIPT ligand, improves the efficiency of metal-to-ligand charge transfer. This finding demonstrates the potential to control the PCET reaction in the desired direction and the efficiency of charge transfer by simply perturbing the external hydrogen-bonding network with the solvent.The iridium complex with an ESIPT ligand shows solvent-modulated proton-coupled electron transfer, in which the temporal order of proton transfer and charge transfer is altered by the solvent environment. 相似文献
294.
Wee Teck Gan 《Compositio Mathematica》1999,118(3):323-344
We consider the restriction of the reflection representation to various reductive dual pairs in exceptional groups, and determine the correspondence of generic representations. 相似文献
295.
COINCIDENCEPOINTTHEOREMSiNPROBABILISTICMETRICSPACESWITHACONVEXSTRUCTURESWeeTaePark(朴渭汰)KeunSaengPark(朴根生)YeolJeCho(赵烈济)(Depar... 相似文献
296.
So-Jeong Lee Heon-Woong Kim Suji Lee Ryeong Ha Kwon Hyemin Na Ju Hyung Kim Chi-Do Wee Seon Mi Yoo Sang Hoon Lee 《Molecules (Basel, Switzerland)》2022,27(1)
Platycodon grandiflorum (PG) is known as a high-potential material in terms of its biological activity. The objective of this report is to provide chromatographic and mass fragment ion data of 38 simultaneously identified saponins, including novel compounds, by analyzing them through ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-QToF/MS). In so doing, we investigated their diverse conditions, including morphological parts (stems, roots, buds, and leaves), peeling (or not), and blanching of PG. The total contents of individual saponins indicated an order of roots (containing peel, 1674.60 mg/100 g, dry weight) > buds (1364.05) > roots (without peel, 1058.83) ≈ blanched roots (without peel, 945.17) ≈ stems (993.71) ≈ leaves (881.16). When considering three types of aglycone, the platycodigenin group (55.04 ~ 68.34%) accounted for the largest proportion of the total content, whereas the platycogenic acid A group accounted for 17.83 ~ 22.61%, and the polygalacic acid group represented 12.06 ~ 22.35%. As they are classified as major compounds, novel saponins might be utilized for their role in healthy food for human consumption. Additionally, during blanching, the core temperature of PG was satisfied with the optimal condition, thus activating the enzymes related to biotransformation. Furthermore, through the use of this comprehensive data, additional studies related to buds, as well as roots or the characterization of individual saponins, can be conducted in a rapid and achievable manner. 相似文献
297.
Zonghan Hong Wee Kiang Chong Andrew Yun Ru Ng Mingjie Li Rakesh Ganguly Tze Chien Sum Han Sen Soo 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(11):3494-3498
Two‐dimensional lead and tin halide perovskites were prepared by intercalating the long alkyl group 1‐hexadecylammonium (HDA) between the inorganic layers. We observed visible‐light absorption, narrow‐band photoluminescence, and nanosecond photoexcited lifetimes in these perovskites. Owing to their hydrophobicity and stability even in humid air, we applied these perovskites in the decarboxylation and dehydrogenation of indoline‐2‐carboxylic acids. (HDA)2PbI4 or (HDA)2SnI4 were investigated as photoredox catalysts for these reactions, and quantitative conversion and high yields were observed with the former. 相似文献
298.
Min‐Quan Yang Lei Shen Yuyao Lu See Wee Chee Xin Lu Xiao Chi Zhihui Chen Qing‐Hua Xu Utkur Mirsaidov Ghim Wei Ho 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(10):3109-3113
A persistent challenge in classical photocatalyst systems with extended light absorption is the unavoidable trade‐off between maximizing light harvesting and sustaining high photoredox capability. Alternatively, cooperative energy conversion through photothermic activation and photocatalytic redox is a promising yet unmet scientific proposition that critically demands a spectrum‐tailored catalyst system. Here, we construct a solar thermal‐promoted photocatalyst, an ultrathin “biphasic” ordered–disordered D‐HNb3O8 junction, which performs two disparate spectral selective functions of photoexcitation by ordered structure and thermal activated conversion via disordered lattice for combinatorial photothermal mediated catalysis. This in situ synthetically immobilized lattice distortion, constrained to a single‐entity monolayer structure not only circumvents interfacial incompatibility but also triggers near‐field temperature rise at the catalyst–reactant complexes’ proximity to promote photoreaction. Ultimately, a generic full solar conversion improvement for H2 fuel production, organic transformation and water purification is realized. 相似文献
299.
Yong-Ki Park Chul Wee Lee Na Young Kang Won Choon Choi Sun Choi Seung Hoon Oh Deuk Soo Park 《Catalysis Surveys from Asia》2010,14(2):75-84
A number of important chemicals are made from light olefins such as propylene and ethylene, and it is expected that market
demand for these light olefins will continue to grow at 4–5% annually, and the average overall growth of propylene will be
about 1% higher than that of ethylene. From the viewpoint of supply of feedstock and demand of light olefins, it is anticipated
that the thermal cracking process of naphtha will be gradually transformed to a catalytic process such as ACOTM that can efficiently produce both ethylene and propylene in high yield. Also, together with primary light olefin production
technologies utilizing heavy feedstocks such as DCCTM, and HPFCC, supplementary propylene production technologies utilizing C4–C4 such as SUPERFLEXTM, MOITM, and PROPYLURTM will be applied gradually in commercial production. 相似文献
300.
Wee Han Ang Rosario Scopelliti Kay Severin 《Journal of organometallic chemistry》2009,694(6):968-1067
Organometallic half-sandwich complexes based on ruthenium with aminomethyl-substituted 3-hydroxy-2-pyridone ligands exist in aqueous solution as monomeric O,O′-chelate complexes or trimeric metallamacrocycles depending upon the pH. We hypothesized that administration of the compounds as stable trimers, which subsequently convert to active monomers at the reduced pH of the cancer environment, could facilitate their delivery to cancer cells without undergoing deactivation. Thus, the compounds were evaluated against cancer and fibroblast cell lines in vitro. A series of rhodium complexes, which exist mainly as monomers at neutral pH, were also studied for comparative purposes. 相似文献