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991.
Jyun-Yi Yeh Shih-Cheng Li Celine H. Chen Prof. Kevin C.-W. Wu Prof. Yi-Pei Li 《化学:亚洲杂志》2021,16(9):1049-1056
Metal-organic framework (MOF) in biomass valorization is a promising technology developed in recent decades. By tailoring both the metal nodes and organic ligands, MOFs exhibit multiple functionalities, which not only extend their applicability in biomass conversion but also increase the complexity of material designs. To address this issue, quantum mechanical simulations have been used to provide mechanistic insights into the catalysis of biomass-derived molecules, which could potentially facilitate the development of novel MOF-based materials for biomass valorization. The aim of this review is to survey recent quantum mechanical simulations on biomass reactions occurring in MOF catalysts, with the emphasis on the studies of the catalytic activity of active sites and the effects of organic ligand and porous structures on the kinetics. Moreover, different model systems and computational methods used for MOF simulations are also surveyed and discussed in this review. 相似文献
992.
The influence of a charged boundary on the electrophoretic behavior of an entity in a non-Newtonian fluid is studied by considering a sphere at an arbitrary position in a spherical cavity filled with a Carreau fluid under the conditions of low surface potential and weak applied electric field. The dependence of the mobility of a sphere on its position in a cavity, the size of a cavity, the thickness of a double layer, and the nature of a fluid is investigated. In addition to the fact that the effect of shear-thinning is advantageous to the movement of a sphere, several other interesting results are also observed. For instance, if an uncharged sphere is in a positively charged cavity, where the electroosmotic flow and the induced charge on the sphere surface play a role, the effect of shear-thinning is important only if the thickness of the double layer is either sufficiently thin or sufficiently thick. However, this might not be the case if a positively charged sphere is in an uncharged cavity. 相似文献
993.
Wu PC Wang WS Huang YT Sheu HS Lo YW Tsai TL Shieh DB Yeh CS 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(14):3878-3885
A low-temperature solution approach (90-95 degrees C) using FeCl(3) and urea was carried out to synthesize beta-FeOOH nanorods in aqueous solution. The as-synthesized beta-FeOOH nanorods were further calcined at 300 degrees C to form porous nanorods with compositions including both beta-FeOOH and alpha-Fe(2)O(3). The derived porous nanorods were engineered to assemble with four layers of polyelectrolytes (polyacrylic acid (PAA)/polyethylenimine(PEI)/PAA/PEI) on their surfaces as polyelectrolyte multilayer nanocapsules. Fluorescein isothiocyanate (FITC) molecules were loaded into the polyelectrolyte multilayer nanocapsules in order to investigate drug release and intracellular delivery in Hela cells. The as-prepared nanocapsules showed ionic strength-dependent control of the permeability of the polyelectrolyte shells. The release behavior of the entrapped FITC from the FITC-loaded nanocapsules exhibited either controlled- or sustained-release trends, depending on the compactness of the polyelectrolyte shells on the nanorod surfaces. Cytotoxicity measurements demonstrate that the native nanorods and the polymer-coated nanorods have excellent biocompatibility in all dosages between 0.1 ng mL(-1) and 100 microgm L(-1). The time dependence of uptake of FITC-loaded nanocapsules by Hela cancer cells observed by laser confocal microscopy indicates that the nanocapsules can readily be taken up by cancer cells in 15 min, a relatively short period of time, while the slow release of the FITC from the initial perimembrane space into the cytoplasm was followed by release into the nucleus after 24 h. 相似文献
994.
The effect of the presence of a charged boundary on the electrophoretic behavior of a particle is investigated by considering a sphere at an arbitrary position in a spherical cavity under conditions of low surface potential and weak applied electric field. Previous analyses are modified by using a more realistic electrostatic force formula and several interesting results, which are not reported in the literature, are observed. We show that the qualitative behavior of a particle depends largely on its position, its size relative to that of a cavity, and the thickness of the electric double layer. In general, the presence of a cavity has the effect of increasing the conventional hydrodynamic drag on a particle through a nonslip condition on the former. Also, a decrease in the thickness of the double layer surrounding a sphere has the effect of increasing the electrostatic force acting on its surface so that its mobility increases. However, this may not be the case when an uncharged particle in placed in a positively charged cavity, where the electroosmotic flow plays a role; for example, the mobility can exhibit a local maximum and the direction of electrophoresis can change. 相似文献
995.
Kuo‐Chen Chiang Fung Fuh Wong Chih‐Shiang Chang Mann‐Jen Hour Yu‐Ling Wang Shaw‐Bing Wen Mou‐Yung Yeh 《Journal of heterocyclic chemistry》2007,44(3):591-596
Recently, New functionalized oxadiazole‐triazolopyridinone hybrid compounds were investigated as photoluminescent materials. In this work, we introduce triazolopyridinone to synthesize a series of oxadiazole‐triazolopyridinone hybrid derivatives as potential photoluminescent materials and explore the effect of modification of the triazolopyridinone moiety. The λmax values of the photoluminescence (PL) spectra of 1,3,4‐oxadiazole‐triazolopyridinone hybrids are promoted to longer wavelengths (470‐486 nm) than the traditional 1,2,3‐triazole derivatives (410‐425 nm) in solutions. PL spectra 5a, 5d , and 5g of the vacuum evaporated films on quartz substrates, with a maximum at 487 nm, shows a red‐shift (~15‐20 nm), with respect to the solution spectrum. The solution fluorescence quantum yields (Φf) were measured, all of which fell into the range 0.65‐0.76, and were determined relative to that of 2‐phenyl‐5‐(4‐biphenyl)‐1,3,4‐oxadiazole in benzene (Φf = 0.80). 1,3,4‐Oxadiazole‐triazolopyridinone hybrid derivatives show clearly non‐reversible reduction processes in cyclic voltammogram measurements. Following spectroscopic studies and observation of the electrochemical behaviors, 1,3,4‐oxadiazole‐triazolopyridinone derivatives were determined to be potential efficient bluegreenish photoluminescent materials. 相似文献
996.
Controlling size, shape and homogeneity of embryoid bodies using poly(ethylene glycol) microwells 总被引:1,自引:0,他引:1
Karp JM Yeh J Eng G Fukuda J Blumling J Suh KY Cheng J Mahdavi A Borenstein J Langer R Khademhosseini A 《Lab on a chip》2007,7(6):786-794
Directed differentiation of embryonic stem (ES) cells is useful for creating models of human disease and could potentially generate a wide array of functional cell types for therapeutic applications. Methods to differentiate ES cells often involve the formation of cell aggregates called embryoid bodies (EBs), which recapitulate early stages of embryonic development. EBs are typically made from suspension cultures, resulting in heterogeneous structures with a wide range of sizes and shapes, which may influence differentiation. Here, we use microfabricated cell-repellant poly(ethylene glycol) (PEG) wells as templates to initiate the formation of homogenous EBs. ES cell aggregates were formed with controlled sizes and shapes defined by the geometry of the microwells. EBs generated in this manner remained viable and maintained their size and shape within the microwells relative to their suspension counterparts. Intact EBs could be easily retrieved from the microwells with high viability (>95%). These results suggest that the microwell technique could be a useful approach for in vitro studies involving ES cells and, more specifically, for initiating the differentiation of EBs of greater uniformity based on controlled microenvironments. 相似文献
997.
Kuo CK Liu IP Yeh CY Chou CH Tsao TB Lee GH Peng SM 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(5):1442-1451
The neutral, monocationic, and dicationic linear trinuclear ruthenium compounds [Ru(3)(dpa)(4)(CN)(2)], [Ru(3)(dpa)(4)(CN)(2)][BF(4)], [Ru(3)(dpa)(4)Cl(2)][BF(4)], and [Ru(3)(dpa)(4)Cl(2)][BF(4)](2) (dpa=the anion of dipyridylamine) have been synthesized and characterized by various spectroscopic techniques. Cyclic voltammetric and spectroelectrochemical studies on the neutral and oxidized compounds are reported. These compounds undergo three successive metal-centered one-electron-transfer processes. X-ray structural studies reveal a symmetrical Ru(3) unit for these compounds. While the metal--metal bond lengths change only slightly, the metal--axial ligand lengths exhibit a significant decrease upon oxidation of the neutral complex. The electronic configuration of the Ru(3) unit changes as the axial chloride ligands are replaced by the stronger "pi-acid" cyanide axial ligands. Magnetic measurements and (1)H NMR spectra indicate that [Ru(3)(dpa)(4)Cl(2)] and [Ru(3)(dpa)(4)Cl(2)][BF(4)](2) are in a spin state of S=0 and [Ru(3)(dpa)(4)Cl(2)][BF(4)], [Ru(3)(dpa)(4)(CN)(2)], and [Ru(3)(dpa)(4)(CN)(2)][BF(4)] are in spin states of S=1/2, 1, and 3/2, respectively. These results are consistent with molecular orbital (MO) calculations. 相似文献
998.
Jeng J Lin MF Cheng FY Yeh CS Shiea J 《Rapid communications in mass spectrometry : RCM》2007,21(18):3060-3068
We describe an innovative approach - using a high concentration of trypsin-modified magnetic nanoparticles (TMNPs) - for the rapid and efficient digestion of proteins at elevated temperature. The required digestion time could be reduced to less than 10 s. After digestion, the TMNPs were collected magnetically from the sample solution for reuse and the digested peptides were characterized using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Protein digestion was optimized when using the TMNPs (5 microg/microL) at 57 degrees C; a significantly high peptide coverage was achieved for protein identification (e.g., 98% for lysozyme). Although a high concentration of TMNPs was used for digestion, the short digestion time led to much lower amounts of trypsin peptides being produced through self-digestion. As a result, interference in the mass spectrometric detection of the peptide ions was reduced significantly. 相似文献
999.
A density functional approach is applied to investigate the effect of molecular structure on wetting behavior of water+amphiphile mixtures. The interaction-site model is employed to describe isomeric amphiphile structures. The hydrogen bonding between water and amphiphile is mimicked by energy enhancement according to specific molecular orientation. The calculations show that these systems exhibit Cahn-type criticality-related wetting transitions and pronounced adsorption behavior difference between isomeric systems. Excellent qualitative agreements with experiments are achieved. 相似文献
1000.
Yin C Huang GC Kuo CK Fu MD Lu HC Ke JH Shih KN Huang YL Lee GH Yeh CY Chen CH Peng SM 《Journal of the American Chemical Society》2008,130(31):10090-10092
EMACs (extended metal-atom chains) offer a unique platform for the exploration of metal-metal interactions. There has been significant advances on the synthesis of EMACs, such as lengthening the chains up to 11 metal atoms thus far, integrating naphthyridine moieties for tuning the charge carried at metal centers, and manipulation of metal-metal interactions. However, the metal centers in EMACs hitherto are limited to first row transition metals which are more labile than those relatively inert ones with electrons filled in the 4d and 5d shells. In this Communication, the synthesis, crystallographic, magnetic, and electrical conducting studies of [Ru5(mu5-tpda)4Cl2] and [Ru5(mu5-tpda)4(NCS)2], the first pentanuclear EMACs of second-row transition metal, are reported. 相似文献