脱湿过程中红黏土热导率的变化试验研究

自然状态下岩土体中的三相组成处于动态变化之中,对土体热传导性能的准确测试造成困难,通过热导率脱湿曲线(TCDC)可间接获取土体的传热性能。为此,以桂林红黏土为研究对象,采用压力板仪和KD2 Pro土壤热特性分析仪,研究了红黏土在脱湿过程中热导率的变化规律。试验结果表明:在进气值之前,土体饱和度不变,3种干密度的土体热导率都有小幅度增加,此阶段主要与吸力变化引起的土体密实度变化有关;当吸力超过进气值后,热导率随饱和度减小逐渐减小,此阶段含水率为影响热导率的主要因素。基于热导率试验结果,采用Lu模型和William模型对红黏土脱湿过程中热导率变化曲线进行拟合,整体上2模型对试验结果拟合较好,可以用于红黏土脱湿过程中热导率变化的模拟。     

内陆干旱区实施最严格水资源管理的关键技术研究——以新疆呼图壁河流域为典型示范区

以最严格水资源管理理念为前提,从最严格水资源管理下的区域水资源综合模拟、水资源管理分配,以及典型研究区流域水资源监测框架核心技术及考核指标的评价体系这4个方面,研究内陆干旱区实施最严格水资源管理的关键技术,且以天山北坡中段呼图壁河流域为典型示范区,揭示流域内水资源的供需规律,建立适应内陆干旱区的最严格水资源管理制度,为实现区域水资源的可持续利用以及支撑区域经济社会的可持续发展提供科学依据和决策建议,为干旱区贯彻和落实最严格水资源管理制度提供科技支撑。     

云南核桃（Juglans sigillata Dode）对流干燥传质模拟

在菲克定律与质量守恒定律的基础上建立了模拟云南核桃干燥过程的一维非稳态传质数学模型．通过边界条件的处理,结合云南核桃热风干燥试验,对其干燥过程中内部各层水分分布进行了模拟预测．将含水率的预测值与试验值对比可知该模型与试验数据吻合得很好,试验条件下云南核桃的有效水分扩散系数变化范围为1.14×10－9～1.73×10－9 m2／s．干燥初期云南核桃表层的含水率下降速度比内层快得多,之后内层含水率下降速度比表层要快,最终各层含水率稳步下降;从表层到中心,湿度梯度随着干燥时间的增加逐渐减小．分析表明在核桃的干燥过程中,外壳是影响水分扩散的主要阻力之一．该模型有助于云南核桃干燥过程传热传质耦合的研究以及复杂模型的建立．     

“阴阳互转”与武术技法哲理思想的和谐统一

中国古典哲学认为:宇宙间一切事物都存在阴阳,一切事物变化无不是相互对应、阴与阳相互作用的结果。阴阳学说理论所体现的中华武术传统文化及思维方式更是典型,是武术理论必不可少的基本构架之一。通过分析、归纳武术技法哲理思想中所蕴涵的"阴阳互转"的哲学思想,希望最终达到与武术技法哲理思想的和谐统一,为进一步学习武术,修炼武术并以此提升习武者自身内涵起到积极作用。     

超声场强化污泥对流干燥热湿耦合迁移过程的数值模拟

为理论上有效预测超声作用对污泥对流干燥过程的影响,基于非平衡热力学理论,建立了超声场作用下污泥对流干燥热湿耦合迁移过程的数学模型.对不同声能密度作用下污泥内部温度及湿度场分布进行数值模拟.结果表明,超声作用可以有效加速污泥内部的湿迁移过程,但超声强化效果随污泥厚度增大而逐渐减弱.此外,超声热效应使污泥温度有所升高,但污泥内部的温度梯度却略有降低,因此,污泥内部由温度梯度引起的湿分扩散并未因超声波作用而得到强化.     

Gelatin supports with immobilized laccase as sustainable biocatalysts for water treatment

Millimeter-size beads of gelatin are manufactured by dripping process to give enzyme supports qualified for micropollutants biodegradation in alternative wastewater treatment. The bead diameter is dependent on the tip diameter, the gelatin solution viscosity and the swelling of polymer chains in the collecting bath. Chemical crosslinking was performed with glutaraldehyde using optimal concentration to give mechanical and thermal properties suitable for application in stirred reactor in aqueous medium. Laccases from Trametes versicolor are grafted on the gelatin beads with glutaraldehyde. Sixty percentage of the initial enzymatic activity, evaluated by the oxidation of 2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)diammonium salt (ABTS) is maintained after 10 successive cycles of reaction. Thermal stability at 60°C of immobilized biocatalysts is improved when compared to free enzymes (45% vs 10% of relative activity after 6 h of incubation). The simplicity of the procedure to form gelatin beads and their properties make them promising bio-based and biodegradable support for enzyme immobilization.     

Spray-coated PDMS/PVDF composite membrane for enhanced butanol recovery by pervaporation

In this study, spray-coating was used to prepare dihydroxypolydimethylsiloxane (PDMS) composite membranes with high flux and separation factor for biobutanol recovery from aqueous solution. A thin, smooth, and defect-free PDMS layer was prepared by spray-coating on polyvinylidene difluoride ultrafiltration membrane with little PDMS penetration. The effects of process parameters for membrane fabrication and pervaporation on membrane performance were investigated. A membrane with 2 μm active layer was obtained with a high flux of 1306.9 g/m² h. The optimal membrane with the highest pervaporation separation index (PSI) (19.15 kg/m² h) showed a total flux of 530.6 g/m² h and a separation factor of 36.1 at 37°C, and a PSI of 65.61 kg/m² h and a flux of 1927.0 g/m² h at 70°C. Membrane performance was affected by feed composition and temperature. Acetone-butanol-ethanol solution and fermentation broth gave lower butanol fluxes and separation factors compared to butanol model solution.     

Comparison of liquid-phase and methanol-swelling crosslinking processes of polyimide dense membrane for CO2/CH4 separation

To overcome the plasticization effect in polyimide membranes, many researchers have proposed crosslinking method. This can reduce an inter-segmental mobility by tightening and rigidifying the polymer chains. However, it is difficult to modify the whole polymer chains throughout the membrane because the reaction can be hindered by the diffusion rate of the crosslinker. In particular, it is hard for bulky crosslinker to penetrate a dense membrane with a small d-spacing. This study investigated the effect of crosslinking a dense Matrimid membrane with p-phenylenediamine (p-PDA) via two different crosslinking methods (i.e., methanol-swelling crosslinking process [M-SCP] and liquid-phase crosslinking process [L-PCP]). Most of the crosslinking reaction in M-SCP occurs on the membrane surface due to difficulty in penetration of the bulky p-PDA into the Matrimid dense membrane. In contrast, the L-PCP allows uniform crosslinking across the membrane. The membranes crosslinked using L-PCP showed excellent chemical resistance. Furthermore, the plasticization phenomenon was not observed in the membranes crosslinked using L-PCP with p-PDA more than 15%. Meanwhile, the membrane crosslinked using M-SCP exhibited poor plasticization and chemical resistance properties. These results showed that the L-PCP method can be more effective for the crosslinking of dense membrane to deliver both high plasticization and chemical resistance.     

Thin-film composite forward osmosis membrane prepared from polyvinyl chloride/cellulose carbamate substrate and its potential application in brackish water desalination

Synthesized by the reaction between α-cellulose and m-tolyl isocyanate (MTI), cellulose carbamate (CC) was blended with polyvinyl chloride (PVC) to fabricate substrates for thin-film composite (TFC) forward osmosis (FO) membranes. The introduction of CC into substrates improved both membrane structure and performance. The substrates exhibited higher porosity and hydrophilicity, and better connective pore structure; while rejection layer exhibited better morphology but limited cross-linked degree decrease after the introduction of CC. According to the results, the CC blend ratio of 10% was the optimal ratio. With this blend ratio, the TFC-10 membrane presented favorable water permeability (1.86 LMH/bar) and structure parameter (337 μm), which resulted in excellent FO performance (water flux with a value of 40.40 LMH and specific salt flux with a value of 0.099 g/L under rejection layer faces draw solution [DS] mode when 1 M NaCl and deionized water were utilized as DS and feed solution). In addition, the TFC-10 membrane showed good water flux and low-sulfate ion leakage in the potential application of brackish water desalination.     

Synthesis and characterization of eugenol-based silicone modified waterborne polyurethane with excellent properties

A eugenol-based silicone-containing monomer 4,4′-(1,1,3,3-tetramethyldisiloxane-1,3-dipropyl)bis-2-methoxyphenol(EUSi) was synthesized from eugenol and 1,1,3,3-tetramethyldisiloxane via the hydrosilylation reaction. And waterborne polyurethane (WPU) with excellent properties was obtained by using EUSi as a type of diol chain extender. The unique combination of rigidity and flexibility in the chemical structure of EUSi greatly facilitated the mechanical properties, thermal properties, and water resistance of WPU. With only a 3% dosage of EUSi, the maximum tensile strength was increased from 6.2 to 22.4 MPa, while the water absorption was decreased from 31.3% to a surprisingly 7.6%. Our work provides a new convenient strategy for the preparation of organosilicon-modified WPU with improved performance.