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排序方式: 共有1134条查询结果,搜索用时 10 毫秒
31.
Jung CY Kim JS Kim HS Ha JM Kim ST Lim HJ Koo SM 《Journal of colloid and interface science》2012,367(1):257-263
Monodispersed, submicron-sized Janus ORMOSIL particles with multiple functional groups were prepared by the selective surface reaction of a monolayer film formed at a hexane-water interface. A well-ordered monolayer film was obtained by self-assembly of ORMOSIL particles with multiple functional groups at hexane-water interface. The photopolymerization of an ordered monolayer containing ORMOSIL particles yields a rigid film strong enough to maintain its integrity for transfer and further chemical reaction. The chemical reaction of this ordered film with organic and inorganic functional groups produced Janus ORMOSIL particles with multiple functional groups. The morphologies, structures, and chemical compositions of monolayer films and Janus ORMOSIL particles were characterized by FT-IR, solid state NMR, X-ray diffraction (XRD), optical microscopy (OM), electron microscopies (SEM and TEM), and confocal laser scanning microscopy. 相似文献
32.
The magnetic structures of the Cu(2)O(3) spin lattices present in Cu(4)O(3) and Ag(2)Cu(2)O(3) were analyzed by studying their spin exchange interactions on the basis of spin dimer analysis. Calculations of spin exchange parameters were calibrated by studying LiCuVO(4) whose intrachain and interchain antiferromagnetic spin exchange parameters are known experimentally. The magnetic phase transition of Cu(4)O(3) at 42.3 K doubles the unit cell along each crystallographic direction. The spin arrangements of the Cu(2)O(3) lattice consistent with this experimental observation are different from conventional antiferromagnetic ordering. Our analysis indicates that spin fluctuation should occur in Cu(4)O(3), low-dimensional magnetism should be more important than magnetic frustration in Cu(4)O(3), and Ag(2)Cu(2)O(3) and Cu(4)O(3) should have similar structural and magnetic properties. 相似文献
33.
Zhenghua Li Chengbin Li Su Bin Park Gyoung Hee Hong Jin Seo Park Byung Jin Song Chul Wee Lee Ji Man Kim 《Research on Chemical Intermediates》2018,44(6):3687-3695
Oxidative desulfurization (ODS) of organic compounds containing sulfur element from a model oil was performed using tungsten oxide catalysts supported on mesoporous silica with cubic Ia3d mesostructure, well-defined mesopores (7.2 nm), high surface area (719 m2/g), and three-dimensional pore network (WO x /KIT-6). The prepared WO x /KIT-6 catalysts (5–20 wt% WO x ) were characterized by X-ray diffraction analysis, N2 sorption measurements, electron microscopy, H2-temperature programmed reduction, Raman spectroscopy, and thermogravimetric analysis. Among the mesoporous catalysts, 10 wt% WO x /KIT-6 exhibited the best catalytic performance. Sulfur-containing organic compounds, such as dibenzothiophene, 4,6-dimethyldibenzothiophene, and benzothiophene, were completely (100 %) removed from the model oil over 10 wt% WO x /KIT-6 catalyst in 2 h. In addition, the catalyst could be reused several times with only slight decrease in catalytic activity. 相似文献
34.
Plasmonic Hotspots in Air: An Omnidirectional Three‐Dimensional Platform for Stand‐Off In‐Air SERS Sensing of Airborne Species 下载免费PDF全文
Gia Chuong Phan‐Quang Dr. Hiang Kwee Lee Hao Wen Teng Charlynn Sher Lin Koh Barnabas Qinwei Yim Dr. Eddie Khay Ming Tan Wee Lee Tok Dr. In Yee Phang Prof. Dr. Xing Yi Ling 《Angewandte Chemie (International ed. in English)》2018,57(20):5792-5796
Molecular‐level airborne sensing is critical for early prevention of disasters, diseases, and terrorism. Currently, most 2D surface‐enhanced Raman spectroscopy (SERS) substrates used for air sensing have only one functional surface and exhibit poor SERS‐active depth. “Aerosolized plasmonic colloidosomes” (APCs) are introduced as airborne plasmonic hotspots for direct in‐air SERS measurements. APCs function as a macroscale 3D and omnidirectional plasmonic cloud that receives laser irradiation and emits signals in all directions. Importantly, it brings about an effective plasmonic hotspot in a length scale of approximately 2.3 cm, which affords 100‐fold higher tolerance to laser misalignment along the z‐axis compared with 2D SERS substrates. APCs exhibit an extraordinary omnidirectional property and demonstrate consistent SERS performance that is independent of the laser and analyte introductory pathway. Furthermore, the first in‐air SERS detection is demonstrated in stand‐off conditions at a distance of 200 cm, highlighting the applicability of 3D omnidirectional plasmonic clouds for remote airborne sensing in threatening or inaccessible areas. 相似文献
35.
Tschirret-Guth RA Koo LS Hoa GH Ortiz De Montellano PR 《Journal of the American Chemical Society》2001,123(15):3412-3417
The pressure stability of the thermophilic CYP119 from Sulfolobus solfataricus and its active-site Thr213 and Thr214 mutants was investigated. At 20 degrees C and pH 6.5, the protein undergoes a reversible P450-to-P420 inactivation with a midpoint at 380 MPa and a reaction volume change of -28 mL/mol. The volume of activation of the process was -9.5 mL/mol. The inactivation transition was retarded, and the absolute reaction volume was decreased by increasing temperature or by mutations that decrease the size of the active-site cavity. High pressure affected the tryptophan fluorescence yield, which decreased by about 37% at 480 MPa. The effect was reversible and suggested considerable contraction of the protein. Aerobic decomposition of iron-aryl complexes of the CYP119 T213A mutant under increasing hydrostatic pressure resulted in variation of the N-arylprotoporphyrin-IX regioisomer (N(B):N(A):N(C):N(D)) adduct pattern from 39:47:07:07 at 0.1 MPa to 23:36:14:27 at 400 MPa. Preincubation of the protein at 400 MPa followed by complex formation and decomposition gave the same regioisomer distribution as untreated protein. The results indicate that the protein is reversibly inactivated by pressure, in contrast to the irreversible inactivation of P450(cam) and other P450 enzymes, and that this inactivation process is modulated by changes in the active-site cavity dimensions. 相似文献
36.
37.
Colloid Journal - An Erratum to this paper has been published: https://doi.org/10.1134/S1061933X21330012 相似文献
38.
I. A. Alnour H. Wagiran N. Ibrahim S. Hamzah B. S. Wee M. S. Elias J. A. Karim 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(3):1231-1237
In standardization NAA, it is necessary to characterize the neutron spectrum parameters such as epithermal neutron flux shape factor (α), thermal to epithermal neutron flux ratio (f), thermal neutron flux (φ th) and epithermal neutron flux (φ epi) in the irradiation facility to determine the concentration of an element in the sample using absolute and k 0 standardization methods. The α and f were determined using Cd-ratio multi monitor method using experimental data obtained in PUSPATI TRIGA Mark II research reactor at four irradiation positions (10, 20, 30 and 40) of the rotary rack. The calculated values of α and f ranged from 0.006 to 0.0281 and 18.56 to 19.12 respectively. The average values of φ th and φ epi were found as 2.33 × 1012 and 1.23 × 1011 n cm?2 s?1 respectively. Moreover, a comparison of the neutron flux parameters in the present study shows an acceptable level of consistency with those of previous studies. 相似文献
39.
Kaili Ji Wee Siang Lim Sam Fong Yau Li Kishore Bhakoo 《Analytical and bioanalytical chemistry》2013,405(21):6853-6861
Aptamers are single-stranded oligonucleotides that are capable of binding wide classes of targets with high affinity and specificity. Their unique three-dimensional structures present numerous possibilities for recognizing virtually any class of target molecules, making them a promising alternative to antibodies used as molecular probes in biomedical analysis and clinical diagnosis. In recent years, cell-systematic evolution of ligands by exponential enrichment (SELEX) has been used extensively to select aptamers for various cell targets. However, aptamers that have evolved from cell-SELEX to distinguish the “stimulus-response cell” have not previously been reported. Moreover, a number of cumbersome and time-consuming steps involved in conventional cell-SELEX reduce the efficiency and efficacy of the aptamer selection. Here, we report a “two-step” methodology of cell-SELEX that successfully selected DNA aptamers specifically against “inflamed” endothelial cells. This has been termed as stimulus-response cell-SELEX (SRC-SELEX). The SRC-SELEX enables the selection of aptamers to distinguish the cells activated by stimulus of healthy cells or cells isolated from diseased tissue. We report a promising aptamer, N55, selected by SRC-SELEX, which can bind specifically to inflamed endothelial cells both in cell culture and atherosclerotic plaque tissue. This aptamer probe was demonstrated as a potential molecular probe for magnetic resonance imaging to target inflamed endothelial cells and atherosclerotic plaque detection. Schematic of SRC-SELEX selection
The cells are activated with stimulus and incubated with single-stranded DNA library. The sequences bound on the activated cells are released and amplified to incubate with naïve cells without stimulation. The sequences unbound to the naïve cells are then incubated with activated cells again and go into the next round of selection. After the selection reaches the end point, the single-stranded DNA collected from the last round is cloned and sequenced for identification 相似文献
40.
Noorzalila Muhammad Niza Kok Tat Tan Zainal Ahmad Keat Teong Lee 《Chemical Papers》2011,65(5):721-729
In this study, biodiesel has been successfully produced by transesterification using non-catalytic supercritical methanol
and methyl acetate. The variables studied, such as reaction time, reaction temperature and molar ratio of methanol or methyl
acetate to oil, were optimised to obtain the optimum yield of fatty acid methyl ester (FAME). Subsequently, the results for
both reactions were analysed and compared via Response Surface Methodology (RSM) analysis. The mathematical models for both
reactions were found to be adequate to predict the optimum yield of biodiesel. The results from the optimisation studies showed
that a yield of 89.4 % was achieved for the reaction with supercritical methanol within the reaction time of 27 min, reaction
temperature of 358°C, and methanol-to-oil molar ratio of 44. For the reaction in the presence of supercritical methyl acetate,
the optimum conditions were found to be: reaction time of 32 min, reaction temperature of 400°C, and methyl acetate-to-oil
molar ratio of 50 to achieve 71.9 % biodiesel yield. The differences in the behaviour of methanol and methyl acetate in the
transesterification reaction are largely due to the difference in reactivity and mutual solubility of Jatropha curcas oil and methanol/methyl acetate. 相似文献