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111.
The dynamic behavior of a spin-1 Ising system with arbitrary bilinear and biquadratic pair interactions is studied by using
the path probability method, and approaches of the system toward the stable or metastable equilibrium states according to
the ratio of interaction parameters and rate constants are presented. In particular, we investigate the relaxation of the
order parameters for temperatures less than, equal to, and greater than the second-order and first-order phase transitions.
From this investigation, the “flatness” property of metastable states is seen explicitly. We also show how a system freezes
in a metastable state as well as how it escapes from one metastable state to the other. 相似文献
112.
Guleli Muge Erdem Safiye S. Ocal Nuket Erden Ihsan Sari Ozlem 《Research on Chemical Intermediates》2019,45(4):2119-2134
Research on Chemical Intermediates - An efficient and general method for the synthesis of substituted 3,4-dimethylisoxazolo[5,4-b]pyridine-5-carboxamide and benzo[b][1,8]naphthyridine-3-carboxamide... 相似文献
113.
Valentin Dybbert Samuel Matthias Fehr Florian Klein Achim Schaadt Anke Hoffmann Elias Frei Emre Erdem Thilo Ludwig Harald Hillebrecht Ingo Krossing 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(37):13069-13073
The influence of a mild difluorine treatment on Cu/ZnO precatalysts for methanol synthesis was investigated. It led to the incorporation of 1.2…1.3±0.1 wt % fluoride into the material. Fluorination considerably increased the amount of ZnOx related defect sites on the catalysts and significantly increased the space‐time yields. Although the apparent activation energy EA,app for methanol formation from CO2 and H2 was almost unchanged, the EA,app for the reverse water‐gas shift (rWGS) reaction increased considerably. Overall, fluorination led to a significant gain in methanol selectivity and productivity. Apparently, also the quantity of active sites increased. 相似文献
114.
A simple method is proposed for the determination and speciation of Mn(II) and Mn(VII) in waters utilizing a macroporous resin, Amberlite XAD-7HP. The batch method was employed and flame atomic absorption spectrometry was used in all determinations. Amberlite XAD-7HP resin was shown to retain Mn(VII) between pH 4 and 12. If the solution contains only one of the species, either Mn(II) or Mn(VII), the resin behaves selectively depending on the pH of the solution. The elution from the sorbent was realized using K2C2O4 in HNO3. The efficiency of the method was checked via spike recovery experiments. The proposed method was successfully applied to industrial wastewater samples and quantitative recoveries (≥96.0%) confirmed the accuracy of the method. 相似文献
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116.
Uzun O Xu H Jeoung E Thibault RJ Rotello VM 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(23):6916-6920
Random polystyrene copolymers grafted with complementary recognition elements were combined in chloroform producing vesicular aggregates, that is, recognition-induced polymersomes (RIPs). Reflection interference contrast microscopy (RICM) in solution, coupled with optical microscopy (OM) and atomic force microscopy (AFM) on solid substrates, were used to determine the wall thickness of the RIPs. Rather than a conventional mono- or bilayer structure (approximately 10 or approximately 20 nm, respectively) the RIP membrane was 43+/-7 nm thick. Structural arrangement of the polymer chains on the RIP wall were characterized by using angle-resolved X-ray photoelectron spectroscopy (AR-XPS). The interior portion of the vesicle membrane was found to be more polar, containing more recognition units, than the exterior part. This gradient suggests that a rapid self-sorting of polymers takes place during the formation of RIPs, providing the likely mechanism for vesicle self-assembly. 相似文献
117.
Metal organic frameworks (MOFs) are a new class of nanoporous materials that have many potential advantages over traditional nanoporous materials for several chemical technologies including gas adsorption, catalysis, membrane-based gas separation, sensing, and biomedical devices. Knowledge on the interaction of guest molecules with the MOF surface is required to design and develop these MOF-based processes. In this review, we examine the importance of identification of gas adsorption sites in MOFs using the current state-of-the-art in experiments and computational modeling. This review provides guidelines to design new MOFs with useful surface properties that exhibit desired performances, such as high gas storage capacity, and high gas selectivity. 相似文献
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120.
Experimental implementation of an optimizing controller based on identified model for the separation of nucleosides in a laboratory scale simulated moving bed (SMB) unit is reported in this study. The manipulative variables are the three external and one internal flow rates while the outputs are productivity, solvent consumption, and purities of extract and raffinate streams averaged over a switching period. The feedback information is the concentration profile of extract and raffinate measured online using two ultraviolet (UV) detectors. Experimental results show that the designed controller is able to operate the SMB units under optimal condition fulfilling the purity requirements. Besides, the controller demonstrated excellent performance in terms of rejecting disturbances that may occur during SMB operations. 相似文献