In the field of biomemorizers, the simultaneous enhancement of resistive switching (RS) performance and environmental robustness, and the understanding the RS mechanism involving interfacial interaction is still challengeable. Herein, the bio-composites by encapsulating graphene (GR), graphene oxide (GO) and reduced graphene oxide (RGO) into chitosan (CS) have been fabricated as memory devices with the structure of FTO/biocomposite/Ag. Among them, FTO/GO@CS(12 %)/Ag biomemorizer exhibits the best RS performance with high ON/OFF ratio (10 5.92 ), and it possesses good thermal (170 degrees C) and irradiation stabilities (UV exposure for 96 h). The RS mechanism is due to the migration of oxygen vacancies accompanied by formation of Ag conducting filaments in the bio-composite films. Therefore, the enhanced resistive switching performance after encapsulating into CS can be explained as the increment of defects, the higher current densities and quenched radicals. Specially, for the first time we find the presence of voltage -induced packing mode changes in GO@CS composite, which can facilitate the migration of oxygen vacancies and render its best RS performance. In all, the more carboxyl groups can strengthen the GO -CS interfacial interactions through the formation of stable hydrogen bonding network and covalent bonds, which can enhance the stabilities and makes the composites be more sensitive to electrical stimulus. The rules drawn in this work will be significant for the construction of new biomemorizers with good environmental robustness.

Micromixing efficiency is an important parameter for evaluating the multiphase mass transfer performance and reaction efficiency of microreactors. In this work, the novel curved capillary reactor with different shapes was designed to generate Dean flow, which was used to enhance the liquid -liquid micromixing performance. The Villermaux-Dushman probe reaction was employed to characterize the micromixing performance in different curved capillary microreactors. The effects of experiment parameters such as liquid flow rate, inner diameter, tube length, and curve diameter on micromixing performance were systematically investigated. Under the optimal conditions, the minimum value of the segmentation factor X-S was 0.008. It was worth noting that at the low Reynolds number (Re < 30), the change of curved shape on the capillary microreactor can significantly improve the micromixing performance with X-S reduced by 37.5%. Further, the correlations of segment index X-S with dimensionless factor such as Reynolds number or Dean number were developed, which can be used to predict the liquidliquid micromixing performance in capillary microreactors.

Electrochemical ammonia synthesis has advantages over the conventional Haber–Bosch process in terms of environment friendliness, sustainability, and cleanliness.

Background: Unbaffled U-shaped mesoscale oscillatory flow reactors (meso-OFRs) are able to achieve low pressure drop, good plug flow and micromixing performance simultaneously at laminar net flow conditions under a wide "operating windows".Method: We focus on the macromixing and micromixing behaviours of unbaffled meso-OFR, where the net flow and oscillation conditions were in the wide range of Ren=17-51 and Reo=16-1350, respectively.Significant findings: The good plug flow and micromixing performance could be achieved simultaneously at low oscillation intensity with the wide "operating windows" of psi<47. It was believed that oscillatory motion led to periodic destruction and reformation of vortices, as the oscillation intensity increased, the large-scale vortices were decomposed into small-scale vortices, resulting in backmixing or axial dispersion. Meanwhile, the empirical formula of micromixing time and velocity ratio in accordance with the power-law relationship was established: tm/t = 0.00277 psi 0.51658. Finally, the oscillatory mechanism was qualitatively validated by Computational Fluid Dynamics (CFD).

d-Allulose is a rare hexose with great application potential, owing to its moderate sweetness, low energy, and unique physiological functions. The current strategies for d-allulose production, whether industrialized or under development, utilize six-carbon sugars such as d-glucose or d-fructose as a substrate and are usually based on the principle of reversible Izumoring epimerization. In this work, we designed a novel route that coupled the pathways of methanol reduction, pentose phosphate (PP), ribulose monophosphate (RuMP), and allulose monophosphate (AuMP) for Escherichia coli to irreversibly synthesize d-allulose from d-xylose and methanol. After improving the expression of AlsE by SUMO fusion and regulating the carbon fluxes by knockout of FrmRAB, RpiA, PfkA, and PfkB, the titer of d-allulose in fed-batch fermentation reached ≈70.7 mM, with a yield of ≈0.471 mM/mM on d-xylose or ≈0.512 mM/mM on methanol.

D-Allulose is an ultra-low calorie sweetener with broad market prospects. As an alternative to Izumoring, phosphorylation-dephosphorylation is a promising method for D-allulose synthesis due to its high conversion of substrate, which has been preliminarily attempted in enzymatic systems. However, in vitro phosphorylation-dephosphorylation requires polyphosphate as a phosphate donor and cannot completely deplete the substrate, which may limit its application in industry. Here, we designed and constructed a metabolic pathway in Escherichia coli for producing D-allulose from D-fructose via in vivo phosphorylation-dephosphorylation. PtsG-F and Mak were used to replace the fructose phosphotransferase systems (PTS) for uptake and phosphorylation of D-fructose to fructose-6-phosphate, which was then converted to D-allulose by AlsE and A6PP. The D-allulose titer reached 0.35 g/L and the yield was 0.16 g/g. Further block of the carbon flux into the Embden-Meyerhof-Parnas (EMP) pathway and introduction of an ATP regeneration system obviously improved fermentation performance, increasing the titer and yield of D-allulose to 1.23 g/L and 0.68 g/g, respectively. The E. coli cell factory cultured in M9 medium with glycerol as a carbon source achieved a D-allulose titer of ≈1.59 g/L and a yield of ≈0.72 g/g on D-fructose.

因催化剂与产物不易分离的问题,氢甲酰化反应催化剂固载化研究受到广泛关注.本文从分子筛、二氧化硅、碳材料、金属氧化物、磁性纳米粒子、有机聚合物和离子液体这些不同负载材料的角度综述了过去十年来的相关研究结果,并对不同载体的优缺点和发展前景进行了简要分析.固载型催化剂分为3种不同的构建方式:载体与配体连接、载体与金属连接以及载体同时与配体和金属连接.第3种构建方式制备的催化剂更稳定,常在二氧化硅作为载体中使用.第一种构建方式为催化剂制备提供了多样性,在无机物和有机物作为载体中都有广泛使用,其中,含磷的有机聚合物在提供良好催化剂效果的同时,也提高了催化剂的稳定性,对未来的研究方向有一定的指导意义.

The solubility of borneol, camphor, and isoborneol in four solvents (i.e., acetone, ethanol, p-cymene, and p-xylene) was measured by the static equilibrium method within the temperature range of 29...

Several Cu/ZnO/Al2O3 catalysts with high Cu and ZnO contents were used to study the influence of solvent polarity on the dehydrogenation and dehydration of isoborneol. The employment of a polar solvent enhanced the activity for the main dehydrogenation reaction, while the use of a non-polar solvent favored the dehydration side-reaction. Different techniques were employed to characterize the fresh, treated, and spent catalysts. X-ray powder diffraction (XRD) showed that the copper was in metallic form and zinc in oxide form, transmission electron microscope (TEM) showed differences in catalyst morphology that depended on the polarity of the solvent used, N2O titration gave the Cu active site density, and temperature-programmed desorption of NH3 (NH3-TPD) provided the acidity of the materials. The characterization results indicated that in non-polar solvents the copper nanoparticles were sintered and this may have been due to the enhanced activity of adventitious water in those solvents or simply because of interactions between the solvents and the copper and zinc oxide components. The sintering resulted in a decrease in the number of active sites and an increase in acidic sites, which enhanced the undesired dehydration reaction. Based on the results of inductively coupled plasma (ICP) and TEM, a model of the catalyst was proposed to illustrate the effect of solvent polarity on the dehydrogenation of isoborneol.

Residue curve maps are a powerful tool for the preliminary design of Reactive Distillation (RD). In this study, residue curve maps of the n-butyl acetate synthesis reaction were calculated based on the Langmuir–Hinshelwood–Hougen–Watson kinetic and UNIQUAC models to calculate the physical properties of the system. The results showed that the unstable node branch emerged from the n-butyl acetate/water edge, moved toward the chemical equilibrium surface with increasing Damkohler number, and no ternary reactive azeotropic point appeared when the reaction was added. Conceptual design of n-butyl acetate synthesis by reactive distillation based on residue curve maps is presented. Based on the simulation results, both the energy consumption and the total annual cost were lower than previously reported values.

以多孔酚醛树脂XAD761为载体,采用表面官能团修饰的方法制备了固载铑膦配合物的催化剂XAD761/P/Rh,实现了均相氢甲酰化反应催化剂的固载化.采用红外光谱、等温氮气吸附和X射线光电子能谱等方法对所制得的催化剂进行表征,证实了二苯基氧磷结构配位中心的存在及铑膦配合物催化中心在酚醛树脂载体表面的形成.经过电感耦合等离子-原子发射光谱测得磷和铑的负载量分别为1.39％和0.40％,催化剂中磷铑比为11.分别以1-辛烯和苯乙烯为底物考察了催化剂的催化性能,结果表明,在一定条件下XAD761/P/Rh在催化活性方面和三苯基膦作配体时的均相催化剂效果相当,1-辛烯和苯乙烯的成醛收率分别可以达到77.9％和99.6％.所制备的催化剂经过简单的过滤分离即可实现循环使用.

The saturated vapor pressures of furfural (FUR), 2-acetylfuran (2AF), and 5-methylfurfural (5MF) and the isobaric vapor–liquid equilibrium (VLE) data for three binary systems (FUR + 2AF, FUR + 5MF, and 2AF + 5MF) at 3.60 and 5.18 kPa were experimentally measured in a Rose–Williams still. The saturated vapor pressures were correlated by the Antoine equation; the binary VLE data were correlated by the nonrandom two-liquid, Wilson, and universal quasichemical models. The VLE of the ternary system of FUR + 2AF + 5MF was predicted by the obtained binary interaction parameters for each model, and the predictions fit well with the experimental data.

The solubility of cefpiramide in five pure solvents (water, ethanol, 1-propanol, 2-propanol, and 1-butanol) and two binary solvent systems (water + ethanol or water + 2-propanol) was measured by a steady-state method, from 278.2 to 303.2 K, under atmospheric pressure. The initial mole fraction of alcohol (ethanol or 2-propanol) in the binary systems ranged from 0 to 1. It is found that the solubility increases with increasing temperature in the experimental range and shows a quasi-S-shaped curve with the increase of the initial mole fraction of alcohol. The modified Apelblat equation was used to simulate the solubility data, and gives a maximum mean relative deviation (MRD) of 0.47% for the single solvent systems, and a maximum MRD of 1.03 and 1.15% for the ethanol + water and 2-propanol + water systems, respectively. The combined model of the Jouyban–Acree and modified Apelblat equations, both temperature-dependent and solvent-composition-dependent, was simplified to correlate the solubility data of binary solvent mixtures in the initial mole fraction range of alcohol from 0 to 0.9, and gives a MRD of 9.83 and 6.49% for the ethanol +water and 2-propanol + water systems, respectively. The dissolution thermodynamic properties in the pure solvents and two binary mixtures were calculated based on the van’t Hoff equation. The calculation results indicate that the dissolution process of cefpiramide is endothermic in the pure solvents, and entropically driven in the four alcohols but not in water. The dissolution process is endothermic in the two binary mixtures.

Cyclohexanol is an important intermediate in the production of adipic acid and ε-caprolactame, and these in turn are used as intermediates for the production of nylons, plasticizers, and pesticides. Traditionally, cyclohexanol is obtained from the oxidation of cyclohexane, however, the process suffer lots of drawbacks including the low selectivity of cyclohexanol, high energy requirement, the explosion risk, and numerous by-products formations. In this paper, a process simulation of reactive distillation using isophorone as cosolvent for the direct hydration of cyclohexene to cyclohexanol was performed. Results showed that the novel process not only got rid of drawbacks owned by the traditional oxidation method, but also improved the conversion and reaction rate of the reactants greatly. Process simulation results also demonstrated that with the increasing Damköhler number (Da), a reactive azeotrope emerged when Da numbers exceeded a critical value of 0.07. Therefore, the reactive distillation could only be practical when Da numbers is below 0.07. During the simulation, the cyclohexene conversion increased with excess water and cosolvent isophorone in the reactive distillation column. Finally, a high-purity cyclohexanol product (99.9mol.%) can be obtained using a decanter and two distillation columns for reactive distillation, with a high cyclohexene conversion of 99.14%, and the isophorone purity well fitted for recycling, and the energy consumption was studied.

The solvent usually forms a large part of the heterogeneous hydration mixture in the biphasic hydration of liquid olefins, and solvent selection greatly affects the hydration conversion. In this work, the hydration of dihydromyrcene (DHM) in two different solvents, i.e., acetone and 1,4-dioxane, was investigated experimentally and mathematically. A theoretical model coupling liquid–liquid phase equilibrium and reaction equilibrium is proposed for evaluating the effects of the solvent on the heterogeneous hydration of DHM. Experiments were performed to obtain unreported parameters for the phase equilibrium and reaction equilibrium and the conversion of DHM in biphasic hydration was then predicted by the coupled model. The effects of the mass feed ratios on the total conversion X of DHM are discussed and varying conversions were observed when different solvents were employed. DHM was more soluble in the acetone system than in 1,4-dioxane, and the conversion of the hydration reaction was higher. This predictive evaluation process based on the overall equilibrium could provide a practical strategy for selecting the optimal solvent for the heterogeneous hydration of DHM and other liquid olefins.

According to the experience of guiding the student to attend the Chemical Engineering Design Competition ( CEDC) , provided by the teachers from Fuzhou University, five promoting effects of CEDC on the cultivation for the students of chemical engineering were summarized. It indicated that this professional competition not only provided a platform for the students to show their talents, but also can promote the cultivation of the students, as well as the teaching reform in several aspects.

Myrcene, an important intermediate for the production of fine chemicals and pharmaceuticals, is mainly produced by the pyrolysis of S-pinene in the industry. The study of the direct pyrolysis of S-pinene was carried out without a catalyst and carrier gas at 573-873 K and under low pressure. In order to clarify the reaction mechanism, the primary intermediates of beta-pinene pyrolysis including myrcene and limonene were also used as raw materials for further pyrolysis. The identification of some small molecules and C10H16 isomers in the products proves that both decomposition reaction and ene reaction take place during the pyrolysis process. Based on the qualitative and quantitative analysis of reaction products, a reaction scheme for the pyrolysis of S-pinene was proposed. With appropriate simplification of the reaction scheme, a phenomenological kinetic model of the competitive parallel and consecutive first-order reaction was built, and exhibited good agreement with the experimental data. The activation energy (E-a) and pre-exponential factor (k(0)) for each pathway were also determined. (C) 2016 Elsevier B.V. All rights reserved.

A packed-bed reactive and extractive distillation column was proposed to recover polyvinyl alcohol by-product methyl acetate. The azeotrope of methyl acetate and methanol from a polyvinyl alcohol plant was used as experimental material. In the reactive and extractive distillation column, methanol was transformed to methyl acetate over a cation-exchange resin. The simulation for this process was carried out by means of the RADFRAC equilibrium stage model in Aspen Plus. The equilibrium-stage model can describe the reactive and extractive distillation column, but heat loss of the laboratory-scale distillation column should be taken into account in the simulation at a low reflux ratio. The effects of several operation parameters, such as the stage number of reaction section, and stage number of non-reaction section, the reflux ratio, the volume ratio of the extractive solvent to the feed mixture, and the feed location on the performance of the reactive and extractive distillation column were investigated. According to the simulation results, a novel process for methyl acetate recovery was developed, and the methyl acetate purity in the distillate and the methanol conversion can reach higher than 99% and 94%, respectively. (C) 2015 Elsevier B.V. All rights reserved.