Estimation of the dimensions of nano-capillaries from gas adsorption data

A new approach is presented to determine the dimensions of cylindrical nanopores from adsorption measurements.     

Ethane adsorption in slit-shaped micropores: influence of molecule orientation on adsorption capacity

Adsorption of ethane in a slit shaped micropore system has been studied by Monte Carlo molecular simulation by considering this hydrocarbon as a two interacting sites molecule. Ethane adsorption in pore sizes from 0.41 to 1.66 nm was simulated at 303 K. Microscopic characteristics of the adsorbed phase have been studied for pores of different size, comparing two density profiles: the molecule centre of mass profile and the molecular interaction site profile. Averaged angle distribution of molecule positions with respect to the slit plane across the pore width has been also obtained by simulation. These results were related to ethane molecule packing efficiency, which is also related to the adsorption capacity in terms of the adsorbed phase density. Packing efficiency presents an oscillation shape as the result of the adsorbate disorder inside the pore. Pressure influence on the adsorption has been studied by following pore filling by simulation. When pore condensation takes place and for pressures above condensation, fluid-fluid interactions are determinant in molecule disorder observed between the two adsorbed layers.     

Evaluation of 3D Printed Gelatin‐Based Scaffolds with Varying Pore Size for MSC‐Based Adipose Tissue Engineering

Adipose tissue engineering aims to provide solutions to patients who require tissue reconstruction following mastectomies or other soft tissue trauma. Mesenchymal stromal cells (MSCs) robustly differentiate into the adipogenic lineage and are attractive candidates for adipose tissue engineering. This work investigates whether pore size modulates adipogenic differentiation of MSCs toward identifying optimal scaffold pore size and whether pore size modulates spatial infiltration of adipogenically differentiated cells. To assess this, extrusion‐based 3D printing is used to fabricate photo‐crosslinkable gelatin‐based scaffolds with pore sizes in the range of 200–600 µm. The adipogenic differentiation of MSCs seeded onto these scaffolds is evaluated and robust lipid droplet formation is observed across all scaffold groups as early as after day 6 of culture. Expression of adipogenic genes on scaffolds increases significantly over time, compared to TCP controls. Furthermore, it is found that the spatial distribution of cells is dependent on the scaffold pore size, with larger pores leading to a more uniform spatial distribution of adipogenically differentiated cells. Overall, these data provide first insights into the role of scaffold pore size on MSC‐based adipogenic differentiation and contribute toward the rational design of biomaterials for adipose tissue engineering in 3D volumetric spaces.     

催化剂的孔道限域效应

限域孔道可以调控催化剂的表面电子分布和几何结构,进而影响催化剂的活性、选择性和稳定性.本文结合理论计算和实验方法,从热力学、动力学、几何效应以及电子转移等角度出发,阐明了不同限域体系中催化剂活性组分和反应分子特性的差异,揭示了限域孔道对反应物种扩散、吸附和反应等过程的影响规律,以期为催化剂的微观结构设计和反应性能调控提供借鉴.     

煤的孔结构特征对水煤浆性质的影响

本文选用１７种不同变质程度的中国煤，详细研究了煤孔结构特征对煤浆性质的影响。发现煤孔体积通过影响煤在分散体系中的吸水性，从而影响煤之成浆性。但由于不同变质程度煤表面亲水性的显著差异，煤孔体积在影响煤成浆性的能力方面差别很大，这使得煤吸水性和浆体最高煤浓度与煤孔体积并不存在直接的相关性，而是取决于煤孔体积Ｖ和以煤－水接触角（θ）的余弦值表示的煤表面亲水性因子的乘积，即煤之有效孔体积：Ｖ×ｃｏｓ（θ／     

Influence of Pore-expansion Agent on the Structure and Performance of Activated Alumina Synthesized from Waste Aluminum Sludge

1 INTRODUCTION The reactivity of activated alumina adsorbent is closely related to its specific surface area: the larger the specific surface area, the better its activity and adsorbent capability are. However, in reality, the prac- tically available specific surface area or effective spe- cific area has relationship with its pore structure[1]. Since many reactant molecules are difficult to enter the pores to react with whose radius is shorter than certain critical value, the increase of p…     

Collapse of a charged radiating star with shear

The junction conditions for a magnetohydrodynamic fluid sphere undergoing dissipative gravitational collapse in the form of a radial heat flux with shear are obtained. These conditions extend particular results of earlier treatments. We demonstrate that the pressure is proportional to the magnitude of the heat flux as is the case in shear-free models. However in our case the gravitational potentials must be solutions of the Einstein-Maxwell system of equations. The mass function m(v) is increased by a factor related to the charge Q of the radiating star. Physical quantities relating to the local conservation of momentum and surface redshift are obtained.     

Fabrication of uniform porous alumina materials by radio frequency (RF) magnetron sputtering

Fabrication of porous materials with uniform pore size distribution remains a challenge. In this paper, a kind of uniform porous alumina material was fabricated on a template of polystyrene microspheres by radio frequency (RF) magnetron sputtering. Surface of samples was observed by scanning electron microscopy (SEM), and the phase of porous materials was confirmed by X-ray diffraction (XRD). The pore size distribution of samples was tested by mercury intrusion method.     

Effects of fiber diameter and CO2 activation temperature on the pore characteristics of polyacrylonitrile based activated carbon nanofibers

The effects of fiber diameter and activation temperature on the pore characteristics of polyacrylonitrile based activated carbon nanofibers are investigated. It was found that lower fiber diameters as well as higher activation temperatures lead to a higher weight loss, specific surface area and total pore volume. The nitrogen adsorption capacity of activated carbon nanofibers is almost three times that of activated carbon fiber with a diameter of 10 µm. As far as the size of pores in activated carbon nanofibers is concerned, it is basically the micropores that dominate the scene. Moreover, tailoring the pore characteristics by adjusting the activation temperature and fiber diameter is plausible. Copyright © 2009 John Wiley & Sons, Ltd.     

Fructose-selective calorimetric biosensor in flow injection analysis

A highly selective, interference free biosensor for the measurement of fructose in real syrup samples was developed. The assay is based on the phosphorylation of d(−)fructose to fructose-6-phosphate by hexokinase and subsequent conversion of fructose-6-phosphate to fructose-1,6-biphosphate by fructose-6-phosphate-kinase. The heat liberated in the second reaction is monitored using an enzyme thermistor. The major advantages of this biosensor are rapid and selective measurement of fructose without the need to eliminate glucose and inexpensive FIA-based, mediator-free calorimetric measurement suitable for regular fructose analysis. This method was optimised for parameters, such as pH, ionic strength, interference, operational stability and shelf life. Good and reproducible linearity (0.5-6.0 mM) with a detection limit of 0.12 mM was obtained. Fructose determination in commercial syrup samples and spiked samples confirmed the reliability of this set-up and technique. The biosensor gave reproducible results with good overall stability for continuous measurements over a period of three months besides a useful shelf life of six months. The method could be used for routine fructose monitoring in food samples.