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991.
Fei Han Guang-Hui Zhang Ping Gu 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(1):369-377
The copper ferrocyanide (CuFC) prepared in this study was characterized using X-ray diffraction and scanning election microscopy. The distribution of particle sizes of the CuFC suspension was determined. The adsorption kinetics data were evaluated for an intraparticle diffusion model, a pseudo-first order model and a pseudo-second order model at temperatures of 288, 298 and 308 K, respectively. It was found that the adsorption process of Cs+ on CuFC was best described by a pseudo-second order kinetic model, with a correlation coefficient (R 2) equal to 1.000, and the adsorption rate constant increased with increasing temperature. This result indicated that chemisorptions took place during the adsorption process. The adsorption equilibrium data fit well to the Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models. The mean adsorption energy (E) between 11 and 13 kJ/mol at different temperatures indicated that ion exchange was the main mechanism during the adsorption process. Thermodynamic parameters were also evaluated during the adsorption. The values of the standard Gibbs free energy change (ΔG o) and standard enthalpy change (ΔH o) suggested that the adsorption was a spontaneous and endothermic process. The distribution coefficient (K d) was more than 2.94 × 106 mL/g when the pH of solution was between 2.6 and 10.9, and the initial Cs+ concentration was 100 μg/L. The existence of K+ and Na+ did not affect the adsorption of Cs+ on CuFC when the concentration of K+ and Na+ in the solution was below 20 and 1,000 mg/L, respectively. 相似文献
992.
采用金属-有机骨架化合物(MOFs)Ce(1,3,5-BTC)(H2O)6为前驱体浸渍Cu2+离子后焙烧得到CuO/CeO2催化剂(B系列),并应用于富氢气氛中CO优先氧化反应(CO-PROX).通过与CuO/CeO2催化剂(A-600)对比发现,不同的MOFs前驱体对催化剂铜活性物种的分散程度有很大影响.X射线衍射分析(XRD)、透射电子显微镜(TEM)和氛气程序升温还原(H2-TPR)等表征均证明B系列催化剂表面铜有聚集现象,由此增加了催化剂的抗H2O和CO2性能. 相似文献
993.
以含巯基官能团有机硅烷修饰的介孔材料MCM-41和SBA-15为载体, 采用浸渍-氢气还原法制备了高分散和高活性的负载型Pd催化剂. X射线衍射、N2吸附-脱附和透射电子显微镜表征结果显示, 所制Pd催化剂Pd-SH-MCM-41和Pd-SH-SBA-15具有很好的长程有序结构、分布均匀的孔径、高比表面积及高度分散的Pd颗粒. 苯酚加氢反应结果表明, 以Pd-SH-MCM-41和Pd-SH-SBA-15为催化剂时, 在80℃, 1.0MPa反应1h, 苯酚转化率达99%以上, 环己酮选择性为98%. 它们的催化活性为商业Pd/C催化剂的5倍, Pd/MCM-41和Pd/SBA-15催化剂的3倍. 这可归因于介孔材料表面修饰的巯基官能团对Pd的锚定作用, 避免了Pd颗粒的团聚, 使其高度分散在介孔材料上. 相似文献
994.
Pradip K. Bhowmik Haesook Han Ivan K. Ndedeltchev James J. Cebe Shin‐Woong Kang Satyendra Kumar 《Liquid crystals》2013,40(8):891-906
Several viologen bis{tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate} salts were prepared by metathesis reaction of the corresponding viologen dibromides (diiodide) with sodium bis{tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate} salt in a polar organic solvent. They were characterized for their physical and thermal properties by experimental techniques including variable temperature X‐ray diffraction. All exhibited low T g and T m, and their T g/T m (K) ratios were in the range 0.66–0.79. Several exhibited polymorphism and formed isotropic ionic melts at <150°C. They were soluble in many common organic solvents such as ethers, alcohols, acetonitrile and methylene chloride. They exhibited photoluminescence in both 1,2‐dimethoxyethane and methanol, as well as in the solid state. In the solid state, the emission spectra exhibited hypsochromic shift when compared with those in solutions of 1,2‐dimethoxyethane and methanol. 相似文献
995.
Yew-Hong Ooi Chun-Chieh Han Hong-Cheu Lin Kenji Kubo Masato M. Ito 《Liquid crystals》2013,40(4):516-527
A series of symmetrical trimeric liquid crystalline compounds of which the molecular structure with a central core of 1,3,5-benzene attached by three rod-like mesogenic Schiff base moieties via the propylene spacers and ether linkages has successfully been synthesised and characterised by infra red and nuclear magnetic resonance spectroscopic techniques. All the star-shaped compounds in this series exhibit predominantly SmC phase except the analogue possessing terminal C8H17 group. It is apparent that the members with even parity from C10H21 to C16H33 show enantiotropic SmC phase while the member with longest terminal chain of C18H37 is inclined to monotropic smectogen. The X-ray diffraction measurements reveal that the tilted smectic layer structures of the SmC phase are confirmed to have an obvious sharp peak at small angles of 2θ ~ 1.03°–1.48° with d-spacing values of 4.01–4.58 nm, which are corresponding to tilt angles of ~48° in the SmC phase. 相似文献
996.
Jie Han Feng-Yan Zhang Juan-Yu Wang Yan-Mei Wang Mei-Li Pang Ji-Ben Meng 《Liquid crystals》2013,40(8):825-833
A series of heterocyclic liquid crystalline compounds containing 1,3,4-oxadiazole/thiadiazole, furan and thiophene units were synthesised and characterised by means of electrospray ionisation-mass spectrometry (ESI-MS), high-resolution mass spectroscopy (HRMS), 1H nuclear magnetic resonance (NMR) and 13C NMR. The thermal behaviours were investigated by differential scanning calorimetry (DSC) and polarised optical microscopy (POM). The effect of the 1,3,4-oxadiazole, 1,3,4-thiadiazole, furan, thiophene and benzene rings on the liquid crystalline properties was discussed briefly in context with the geometrical and electronic factors. The results showed that the tendency to form mesophases follows the sequence: 1,4-disustituted benzene >2,5-disubstituted thiophene >2,5-disustituted furan and 1,3,4-thiadiazole >1,3,4-oxadiazole. 相似文献
997.
Ioan Paraschiv Alistair Tomkinson Marcel Giesbers Ernst J. R. Sudh?lter Han Zuilhof Antonius T. M. Marcelis 《Liquid crystals》2013,40(9):1029-1038
The synthesis and thermotropic properties are reported for a series of hexaalkoxytriphenylenes that contain an amide, urea or thiourea group in one of their alkoxy tails. The intermolecular hydrogen bonding abilities of these molecules have a disturbing influence on the formation and stability of the columnar liquid crystalline phases. The stronger the hydrogen bonding the more the liquid crystallinity is suppressed, probably due to disturbance of the π–π stacking of the triphenylene discs. As a direct result, urea‐ and amide‐containing triphenylene derivatives are not liquid crystalline, but several thiourea derivatives show hexagonal columnar mesophases. 相似文献
998.
Jie Han Feng‐Yan Zhang Zhi Chen Juan‐Yu Wang Li‐Rong Zhu Mei‐Li Pang 《Liquid crystals》2013,40(12):1359-1365
A series of new compounds based on aromatically 2,5‐disubstituted 1,3,4‐oxadiazoles without flexible chains, formulated as p‐R–C6H4–(OC2N2)–(p‐C6H4)2–R′ with (i) R = CH3O, R′ = CH3O, CH3S, F, H (Ia–Id), (ii) R = CH3S, R′ = CH3O, CH3S, F, H (IIa–IId) and (iii) R = F, R′ = CH3O, CH3S, F, H (IIIa–IIId) (p‐C6H4 and OC2N2 represent a p‐phenylene spacer and a 1,3,4‐oxadiazole ring, respectively), were synthesised and characterised by 1H and 13C NMR, MS and HRMS techniques. Mesomorphic properties were investigated using differential scanning calorimetry and polarizing optical microscopy. All of the target compounds (except Id, IId, IIIc and IIId) exhibited an enantiotropic nematic mesophase with high melting temperatures. The liquid crystalline properties of these compounds were influenced greatly by polarity, steric factors and positions of the terminal groups. The effect of the terminal groups on the liquid crystal properties is discussed. 相似文献
999.
Guan Chunfeng Li Xiaozhou Wang Gang Ji Jing Jin Chao Tchouopou Lontchi Josine 《Applied biochemistry and biotechnology》2013,169(2):636-650
Cholera toxin B-subunit (CTB) has been widely used to facilitate antigen delivery by serving as an effective mucosal carrier molecule for the induction of oral tolerance. However, whether CTB can be used as a transmucosal carrier in the delivery of not only vaccines but also therapeutic proteins has not been widely studied. Thus, we investigate here the concept of receptor-mediated oral delivery of lumbrokinase (LK) proteins which is an important fibrinolytic enzyme derived from earthworm. CTB and LK, separated by a furin cleavage site, was expressed via Pichia pastoris. The activity and proper folding of recombinant protein in yeast were confirmed by Western blot analysis, fibrin plate assays, and GM1-ganglioside ELISA. Following oral administration of recombinant protein, the thrombosis model of rats and mice revealed that the oral treatment of rCTB–LK has a more significant anti-thrombotic effect on animals compared with rLK. It is possible to conclude that CTB can successfully enhance its fusion protein LK to be absorbed. The use of CTB as a transmucosal carrier in the delivery of not only vaccines but also therapeutic proteins was supported. 相似文献
1000.
Chang Geun Yoo Chao Wang Chenxu Yu Tae Hyun Kim 《Applied biochemistry and biotechnology》2013,169(5):1648-1658
Photocatalyst-assisted ammonia pretreatment was explored to improve lignin removal of the lignocellulosic biomass for effective sugar conversion. Corn stover was treated with 5.0–12.5 wt.% ammonium hydroxide, two different photocatalysts (TiO2 and ZnO) in the presence of molecular oxygen in a batch reactor at 60 °C. Various solid-to-liquid ratios (1:20–1:50) were also tested. Ammonia pretreatment assisted by TiO2-catalyzed photo-degradation removed 70 % of Klason lignin under the optimum condition (12.5 % ammonium hydroxide, 60 °C, 24 h, solid/liquid?=?1:20, photocatalyst/biomass?=?1:10 with oxygen atmosphere). The enzymatic digestibilities of pretreated corn stover were 85 % for glucan and 75 % for xylan with NH3-TiO2-treated solid and 82 % for glucan and 77 % for xylan with NH3-ZnO-treated solid with 15 filter paper units/g-glucan of cellulase and 30 cellobiase units/g-glucan of β-glucosidase, a 2–13 % improvement over ammonia pretreatment alone. 相似文献