Chromatographic characterisation of aptamer-modified poly(EDMA-co-GMA) monolithic disk format for protein binding and separation

The introduction of aptameric ligands onto disk-monolithic adsorbent, representing a unique strategy for convective isolation of target molecules with high specificity and selectivity, is investigated for the first time. Experimental results showed that the disk monolith possessed a good permeability of 1.67 ± 0.05 × 10^–14 m² (RSD = 3.2%). The aptameric ligand density for the aptamer-modified disk monolith was 480 pmol/uL. Chromatographic analysis of the aptamer disk-monolith efficiency showed an optimum linear velocity of 126 cm/min (≈0.25 mL/min) at room temperatures 25 ± 2°C. The theoretical number of plates corresponding to the optimum linear velocity was 128.2 with an height equivalent to the theoretical plate of 0.022 mm. The disk aptamer-immobilised monolithic system demonstrated good selectivity and isolation of thrombin from non-targets.     

Preparation and characterisation aspects of carbon-coated monoliths

Carbon-coated monoliths have been prepared by dipcoating cordierite monoliths in a polymer solution and subsequent carbonisation. Parameters of preparation that were varied were viscosity of the dipcoating solution, carbon precursor and carbonisation temperature. Two different commercial polymers have been used as carbon precursors, Novolac and Furan resins. Also monoliths have been coated with slurry of such resins and a commercial mesoporous activated carbon (CP-97).

The features of the final carbon that have been optimised are carbon loading, carbon layer thickness, coverage and mesoporosity. Coverage has been tested by leaching test in acid media. Both coverage and mesoporosity are considerably enhanced when the dipcoating mixture was a slurry of Furan resin and a commercial activated carbon. These features makes carbon-coated monoliths very suitable for their use as catalyst support in three-phase reactions.     

Evaluating unidirectional composite thermal conductivities through engineered interphase

ABSTRACT

Effect of fibre/matrix interphase parameters, including thickness and material properties on the equivalent thermal conductivities of unidirectional fibre-reinforced polymer composites. A unit cell-based micromechanical method is proposed to evaluate the thermal conductivities of unidirectional multi-phase composites. The longitudinal thermal conductivity of unidirectional fibre-reinforced polymer matrix composites is seen to be independent of interphase region. When the thermal conductivity of interphase is higher than that of matrix, the increase of interphase thickness leads to an improvement in transverse thermal conductivity of fibre-reinforced polymer composites. The influences of fibre volume fraction, orientation angle and shape of cross-section as well as temperature on the thermal conducting behaviour are widely examined. The model predictions are in good agreement with the experimental data reported in the literature.     

SEPARATION OF AIRBORNE DUST IN ELECTROSTATICALLY ENHANCED FIBROUS FILTERS

The removal of small charged dust particles from a gas stream using an external electric field is common in many industrial applications. In the present paper, the feasibility of using electrostatically enhanced fibrous filters (EEFFs) to separate high concentration dusts from a contaminated gas stream is studied and models to predict both the pressure drop through the filter and the collection efficiency in the dust laden filter are proposed and these models are confirmed by experiments.     

ENHANCEMENT OF THE SEDIMENTATION RATES OF FIBROUS SUSPENSIONS

The settling of suspensions of slender rod-like particles with large aspect ratios was studied. The novel technique of enhancement of sedimentation rates by the addition of buoyant particle promoters was applied to such suspensions. The settling rates could be increased by many times by this simple technique. Sedimentation velocity increases of between 5 to 7 times have been observed for fibrous suspensions of concentrations of about 0.5%. A statistical analysis of the experimental data was performed to establish a correlation for the enhancement in settling velocities. The sediment volume was unaffected by the presence of buoyant particles. The buoyant parjticles were found to adsorb some surfactants onto their surfaces.     

Improvement in the properties of low carbon MgO-C refractories through the addition of graphite-SiC micro-composite

Graphite–SiC micro-composites have been prepared in–house by carbothermal reduction process. Controlling the process parameters including the weight ratio of SiO₂ to graphite as well as carbothermal reduction temperature during the micro-composite preparation favors the homogeneous formation of SiC with preferred morphologies like ribbons and whiskers/fibers. The micro-composite modified low carbon MgO-C refractories have exhibited significantly improved bulk properties over the standard composition. To understand the beneficial role of SiC reinforcement on hot strength performance under air oxidizing conditions, we propose a scaling parameter known as strength factor (fs) based on the ratio of hot strength (HMOR) to cold strength (CCS). Correlating the strength factor data (fs) with oxidative damage provides new insights into the reinforcing effects of distinct SiC morphologies in this new class of micro-composite fortified refractory systems over the standard compositions.     

An experimental investigation of Fischer–Tropsch synthesis over washcoated metallic structured supports

In principle, the application of monolithic catalysts to the Fischer–Tropsch synthesis can solve many of the problems related to the classical Fischer–Tropsch reactors, in particular concerning the necessity to operate with short diffusion distances and low pressure drops, preferably according to the ideal plug-flow behavior, while still maintaining a reasonable inventory of catalytic material in the reactor volume.The preparation of prototype cobalt-based catalysts, washcoated onto metallic structured supports with different geometries, is described herein, together with the evaluation of the catalytic properties of such systems in the Fischer–Tropsch synthesis at industrially relevant process conditions (220–235 °C, 20 bar, 2.1  mol_H2/mol_CO,  5000 cm³(STP)_CO+H2/h/g_cat). Comparative tests with the same catalyst in the powdered form were also carried out at the same process conditions.It was found that the structured catalysts maintained the activity and the selectivity of the original powdered catalyst, provided that the washcoat thickness is sufficiently thin.     

Wound-dressing materials with antibacterial activity from electrospun gelatin fiber mats containing silver nanoparticles

Ultrafine gelatin fiber mats with antibacterial activity against some common bacteria found on burn wounds were prepared from a gelatin solution (22%w/v in 70 vol% acetic acid) containing 2.5 wt% AgNO₃. Silver nanoparticles (nAg), a potent antibacterial agent, first appeared in the AgNO₃-containing gelatin solution after it had been aged for at least 12 h, with the amount of nAg increasing with increasing aging time. The average diameters of the as-formed nAg ranged between 11 and 20 nm. Electrospinning of both the base and the 12 h-aged AgNO₃-containing gelatin solutions resulted in the formation of smooth fibers, with average diameters of ∼230 and ∼280 nm, respectively. The average diameter of the as-formed nAg in the electrospun fibers from the 12 h-aged AgNO₃-containing gelatin solution was ∼13 nm. The nAg-containing gelatin fiber mats were further cross-linked with moist glutaraldehyde vapor to improve their stability in an aqueous medium. Both the weight loss and the water retention of the nAg-containing gelatin fiber mats in acetate buffer (pH 5.5), distilled water (pH 6.9) or simulated body fluid (SBF; pH 7.4) decreased with increasing cross-linking time. The release of Ag⁺ ions from both the 1- and 3 h-cross-linked nAg-containing gelatin fiber mats - by the total immersion method in acetate buffer and distilled water (both at a skin temperature of 32 °C) - occurred rapidly during the first 60 min, and increased gradually afterwards; while that in SBF (at the physiological temperature of 37 °C) occurred more gradually over the testing period. Lastly, the antibacterial activity of these materials, regardless of the sample types, was greatest against Pseudomonas aeroginosa, followed by Staphylococcus aureus, Escherichia coli, and methicillin-resistant S. aureus, respectively.     

梯度纤维多孔材料的吸声特性及结构优化

利用金属纤维为原料,制成内部具有梯度孔结构的金属纤维多孔吸声材料。梯度孔结构可分为孔隙度梯度和丝径梯度,分别研究了这2种梯度结构的吸声特性。结果表明,厚度在6~30 mm范围内时,孔隙度梯度结构按照孔隙度从大到小的顺序排列有利于提高全频的吸声性能;厚度为3 mm时,孔隙度梯度结构的排列顺序对吸声性能的影响规律恰好相反;丝径梯度结构的吸声特点是当厚度为3 mm时,细丝径纤维多孔材料在前,全频吸声性能较好;当厚度≥15mm时,粗丝径纤维多孔材料在前,全频吸声性能好;厚度在3~15 mm之间,2种排列方式的丝径梯度结构的吸声-频率曲线存在一个交点,随着厚度的增加,该交点逐渐向低频方向移动。     

金安桥水电站左岸坡坝段群抗震性能研究

针对金安桥水电站左岸坡坝段群设防烈度高、坝基构造复杂和坝体横缝结构特殊的特点,对横缝进行了一系列合理的简化并应用动力分析方法对左岸坡坝段群进行了抗震性能分析。分析结果表明:金安桥水电站左岸坡坝段群在9度地震作用下,坝踵、坝趾处的抗拉、抗压强度和单个坝段、坝段群的抗震稳定性均满足现行抗震规范要求,说明金安桥水电站大坝设计合理,能够抵御设防地震。