《矿业科学技术学报(英文版)》2017,27(5):867-871

A method of hydraulic grid slotting and hydraulic fracturing was proposed to enhance the permeability of low permeability coal seam in China. Micro-structural development and strength characteristics of coal were analysed to set up the failure criterion of coal containing water and gas, which could describe the destruction rule of coal containing gas under the hydraulic measures more accurately. Based on the theory of transient flow and fluid grid, the numerical calculation model of turbulence formed by high pressure oscillating water jet was used. With the high speed photography test, dynamic evolution and pulsation characteristics of water jet water analysed which laid a foundation for mechanism analysis of rock damage under water jet. Wave equation of oscillating water jet slotting was established and the mechanism of coal damage by the impact stress wave under oscillation jet was revealed. These provide a new method to study the mechanism of porosity and crack damage under high pressure jet.Fracture criterion by jet slotting was established and mechanism of crack development controlled by crack zone between slots was found. The fractures were induced to extend along pre-set direction,instead of being controlled by original stress field. The model of gas migration through coal seams after the hydraulic measures for grid slotting and fracking was established. The key technology and equipment for grid slotting and fracking with high-pressure oscillating jet were developed and applied to coal mines in Chongqing and Henan in China. The results show that the gas permeability of coal seam is enhanced by three orders of magnitude, efficiency of roadway excavation and mining is improved by more than 57%and the cost of gas control is reduced by 50%.  相似文献   

    

《Starch - St?rke》2017,69(11-12)

  相似文献   

    

Faiz M. Mahdi  Richard G. Holdich 《分离科学与技术》2017,52(1):1-12

Well-known analytical equations for predicting permeability are generally reported to overestimate this important property of porous media. In this work, more robust models developed from statistical (multivariable regression) and Artificial Neural Network (ANN) methods utilised additional particle characteristics [‘fines ratio’ (x₅₀/x₁₀) and particle shape] that are not found in traditional analytical equations. Using data from experiments and literature, model performance analyses with average absolute error (AAE) showed error of ~40% for the analytical models (Kozeny–Carman and Happel–Brenner). This error reduces to 9% with ANN model. This work establishes superiority of the new models, using experiments and mathematical techniques.  相似文献   

    

Amnon C. Sintov  Giora Enden 《Drug development and industrial pharmacy》2017,43(5):830-838

Abstract

The purpose of this study was to investigate a new polymeric system and production process in which self-assembled doxorubicin-loaded nanoparticles were synthetized by using a water-in-oil microemulsion as a template and calcium ions as cross-linkers. The manufacturing process combined cross-linking of carbomer within a W/O microemulsion followed by a phase-separation technique to avoid using organic solvents for extraction. To assess the sustained release behavior of doxorubicin from the nanoparticles, we have developed a new simple method based on the permeability coefficient of a synthetic membrane mounted on Franz diffusion cell system. Franz cells were preferred over the commonly used dialysis tubing because they provide adequate measures of the diffusion area as well as the volumes of the media in both sides of the membrane. The lower permeability values obtained for nanoparticles have shown that the release is a limiting step of the diffusion process, while the calculated straight lines may imply that the apparent release rate of the nanoparticle ensembles is close to a zero-order kinetics. The new drug release method for the evaluation of nano-carriers, utilizing a simple linear model to determine the permeability coefficient, has been proposed for perfect sink and non-sink conditions.  相似文献   

    

Hyok Kwon  Dowan Kim  Kang‐dae Lee  Jongchul Seo  Hwal‐Jong Lee 《Packaging Technology and Science》2017,30(5):195-208

Tyvek^®, as an ethylene oxide (EtO) gas sterile medical packaging material with a high‐gas permeation and serving as an excellent microbial barrier, must be coated with heat‐sealable adhesives to thermally seal various plastic packaging trays or films. Tyvek^® sheet coated with heat‐sealable adhesives must have both porous structure and good sealing strength to various substrates. In this study, an acid pre‐coating method was distinctively introduced to minimize reactions between the blowing agent and acid during mixing, to resultantly generate ethyl vinyl acetate (EVA) layers with porous structure on Tyvek^® sheets. To determine the feasibility of applying the as‐prepared coated Tyvek^® as a sterile medical packaging material, we investigated the properties of the coating solution and coated Tyvek^® as a function of process and additive composition. Finally, EtO gas sterilization tests were performed, and property changes in the coated Tyvek^® were investigated. Properties of the coated Tyvek^® were strongly dependent on the pre‐coating process and the composition of various additives. Pre‐coating with citric acid led to less of a reaction between citric acid and ammonium carbonate as a blowing agent during mixing and resulted in both good seal strength and air permeation for the coated Tyvek^® sheets. The coated Tyvek^® sheets, composed of a water‐based EVA emulsion solution with various additives, were not affected by the EtO sterilization process and yielded good resistance to humidity, EtO gas and vacuum cycles. The coated Tyvek^® sheets prepared by applying an acid pre‐coating may be a promising candidate for gas sterilizable medical device packaging materials. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

    

Stefano Gazzotti  Marco A. Ortenzi  Giulio Piva  Luciano Piergiovanni 《Packaging Technology and Science》2017,30(10):645-661

Cellulose nanocrystals (CNCs) are unique, renewable top‐down nano particles from which coatings with improved gas barrier properties and new functionalities can be prepared. In this paper, the potential for obtaining such high performing nanocrystals from low‐cost lignocellulosic by‐products or raw materials is proved by a comparison study on CNCs obtained both from cotton linters and kraft pulp, by means of the ammonium persulfate (APS) process. Morphological and chemical characterization of the nanocrystals obtained, as well as the main functional properties of the poly(ethylene terephthalate) coated films, showed quite similar characteristics and performances of CNCs obtained from pure cellulose raw material (cotton linters) and the nanoparticles produced from a potential discard of paper making processes (kraft pulp). In particular, the gas barrier properties of the coating produced with CNCs obtained from kraft pulp were very promising, providing oxygen and carbon dioxide permeability values hundreds of times lower than those of equal thickness in comparison with common barrier synthetic polymers, over a broad range of temperatures. The results obtained are relevant not only for the outstanding performances achieved, but also because they evoke a possible positive example of industrial symbiosis in the packaging field, merging together the requirements and needs of the paper and plastic industries and addressing the way towards a better management of waste and materials. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

    

Wenhui Liu  Shumei Mi  Zheng Ruan  Jing Li  Xugang Shu  Kang Yao  Min Jiang  Zeyuan Deng 《Journal of food science》2017,82(2):562-567

Dietary amino acids provide various beneficial effects for our health. The aim of the present study was to assess the effects of tryptophan (Trp) supplementation on barrier function. Ninety‐six healthy finishing pigs (initial body weight 51.49 ± 1.12 kg) were randomly allocated into 2 treatment groups, control group, and 0.2% Trp group. The control group was fed the basal diet, and 0.2% Trp group was fed basal diet plus 0.2% Trp. The trial period is 60 d. Compared with control group, the mRNA abundance of claudin‐3 and zonula occluden‐1 (ZO‐1) in the jejunum in 0.2% Trp group (P < 0.05) was increased. According to immunohistochemistry and immunoblotting test, the expression of ZO‐1 in jejunum in 0.2% Trp group was also significantly increased compared with the control group (P < 0.05). These results revealed that Trp enhanced the expression of tight junction protein ZO‐1 in the intestine of pig model. Trp may be potential and beneficial dietary functional factor for regulating the intestinal development and inhibiting intestinal aging.  相似文献   

    

《Bautechnik》2017,94(9):613-623

Comparative investigations on spatial passive earth pressure by the kinematic element method The determination of earth pressures belongs to the fundamental tasks in geotechnical engineering and is generally treated as a load capacity problem. Using the Kinematic Element Method (KEM), which is an appropriate method for the prediction of limit states, the spatial passive earth pressure is examined. From the results the earth pressure coefficients are determined for variable friction angles, wall friction angles as well as wall geometries. These coefficients are presented in tables and diagrams. Comparing the KEM results to other kinematic approaches as well as the German standard, it turns out that good estimation of the spatial passive earth pressure is possible already with simple mechanisms. Further refinement may additionally improve the quality of the results.  相似文献   

    

Xiaomeng Guo  Wei Li  Jialin Zhou  Wanqing Hou  Xue Wen  Hanbo Zhang  Fenfen Kong  Lihua Luo  Qingpo Li  Yongzhong Du  Jian You 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(15)

Endometriosis is difficult to treat since the side effects of the current therapeutic method and the high recurrence rate; thus, newer and safer therapeutic approaches are urgently needed. This work investigates the enhanced permeability and retention effect of CdTe quantum dots (QDs) and hollow gold nanospheres (HAuNS) in endometriosis to increase the delivery of HAuNS into lesion cells. The surface of HAuNS is successfully conjugated with a TNYL peptide that has specific affinity for the EphB4 receptor, which is a member of the Eph family of receptor tyrosine kinases. It is found that the EphB4 receptor is overexpressed in endometriosis lesions. The data indicate that both QDs and HAuNS can efficiently accumulate in endometriotic lesions through permeable vessels and the TNYL‐conjugated HAuNS (TNYL‐HAuNS) accumulate more via the interaction with EphB4. The specific photothermal ablation therapy based on TNYL‐HAuNS significantly inhibits the growth of the endometriotic volume and induces the atrophy and degeneration of ectopic endometrium with no detectable toxicity to the normal organs. The level of TNF‐α and estradiol also significantly decreases in the endometriotic lesions, indicating that the treatment enables a recovery from hormonal imbalance and inflammatory injury. This work can be a valuable reference for future endometriosis therapy.  相似文献   

    

《工程（英文）》2017,3(6):863-870

The history of the formation of the alpine region is affected by the activities of the glaciers, which have a strong influence on underground works in this area. Mechanized tunneling must adapt to the presence of sound and altered rock, as well as to inhomogeneous soil layers that range from permeable gravel to soft clay sediments along the same tunnel. This article focuses on past experiences with tunnel-boring machines (TBMs) in Switzerland, and specifically on the aspects of soil conditioning during a passage through inhomogeneous soft soils. Most tunnels in the past were drilled using the slurry mode (SM), in which the application of different additives was mainly limited to difficult zones of high permeability and stoppages for tool change and modification. For drillings with the less common earth pressure balanced mode (EPBM), continuous foam conditioning and the additional use of polymer and bentonite have proven to be successful. The use of conditioning additives led to new challenges during separation of the slurries (for SM) and disposal of the excavated soil (for EPBM). If the disposal of chemically treated soft soil material from the earth pressure balanced (EPB) drive in a manner that is compliant with environmental legislation is considered early on in the design and evaluation of the excavation mode, the EPBM can be beneficial for tunnels bored in glacial deposits.  相似文献