Fast Generation and Surface Structuring Methods for Terrain and Other Natural Phenomena

Fractal geometry has proven to be a powerful tool for modeling natural phenomena. Using discrete approximations to fractional Brownian motion over a finite grid plane, computer graphics terrain-rendering algorithms are able to generate highly realistic topographical displays. Similar procedures can be applied to model other natural phenomena, such as clouds and water. Two important considerations in these algorithms are computational efficiency and the ability to control macroscopic surface features. Here we introduce a technique for structuring surface features so as to conform to a specified “elevation” envelope. We also present methods for implementing this technique using a recursive random midpoint-displacement procedure.     

High-performance liquid chromatography of amino acids, peptides and proteins. CXXXIX. Impact of operating parameters in large-scale chromatography of proteins

Large-scale chromatography has been playing an important role in downstream treatment processing in biotechnology. In order to improve the productivity, the throughput of the chromatographic equipment was often increased by increasing the flow-rate and/or by increasing the column sample loading. This paper reports the results of a study on the impact of these and other operating parameters in affinity and ion-exchange chromatographic columns when used for protein purification. A sectional model was developed to predict protein adsorption processes in a packed column. The formulations of this mathematical model are presented in the Appendix. The present study was carried out with computer simulation based on this model and using data obtained from laboratory-scale columns. This model can simulate both the adsorption and washing stages of the protein purification process for both porous and non-porous particles. The effects of changing operating parameters were simulated and contour plots were generated for the easy identification of these effects. It was shown that both flow-rate and column loading can have a considerable impact on the processing rate and the yield of the column. As for the column capacity utilization, the impact of changing flow-rate is not significant at column loading of less than 80% in the test case. It was suggest that the present investigation provides a systematic predictive strategy which will greatly reduce the need for expensive, labour-intensive and time-consuming experimental work during process scale-up.     

Self-sealing property of concrete—Experimental evidence

Leak-tightness of concrete is often judged in terms of the D'Arcy coefficient determined by the flow of water through saturated concrete at a constant rate. In the case of flow through saturated concrete, this rate often reduces with time and reaching a constant value may take many days. The present experiments were designed to explore various models in order to account for this behaviour. The results obtained support the concept that the dissolution and redeposition of alkalis is the most significant mechanism in the time-dependent reduction of flow of water in saturated concrete. Permeability of saturated concrete and self-sealing may be used as measures of the “immune” systems and potential durability of different concretes.     

THE STABILITY OF LATEX PARTICLES IN AQUEOUS SUSPENSIONS

Monodisperse polystyrene-DVB latices of 2, 4 and 9 µm diameter as supplied by SINTEF* for intended use by BCR** as particle standards with respect to both particle size and particle number density have been studied by a variety of techniques, and under a variety of storage conditions. The sizing and counting techniques employed light microscopy, electron microscopy (both transmission and scanning) and Coulter counting. Polymeric stabilizer and bacteriocide additives were employed at different levels and their effects on long term (3 years) stability monitored at different particle number densities. Accelerated ageing experiments employed included elevated and reduced temperatures, light exposure, centrifugation and freeze - thaw cycles. The latices were shown to be remarkably stable in the presence of the selected stabilizer/bacteriocide combination.     

Characterization of vertebral strength using digital radiographic analysis of bone structure

Bone mineral densitometry (BMD) is useful in predicting fracture risk, but, unfortunately, there is a significant degree of overlap in BMD measurements of patients who have a high risk of fracture and patients with a low risk of fracture. In this study, a method of characterizing trabecular bone structure in digitized radiographs of vertebrae is proposed and assessed. A significant correlation between bone "structure" and the compressive strength of vertebral bodies was found. The utility of the parameter for distinguishing between "weak" and "strong" bone samples was assessed using receiver operating characteristic (ROC) analysis. Using this analysis, the structural parameter produced an area under the ROC of 0.88 +/- 0.05, while a bone density measure produced an area of 0.79 +/- 0.07. The results suggest that the addition of a measure of bone structure to the conventional measures of bone density may prove useful in predicting the quality of bone when considering surgical or medical intervention for osteoporotic conditions.     

Photo-lithographic patterning of biomimetic molecularly imprinted polymer thin films onto silicon wafers

This investigation describes the design and synthesis of molecularly imprinted polymers (MIPs) as patterned thin films, based on molecular modelling of functional monomer-template interactions and validation by NMR-spectroscopy. Several MIP thin films were prepared from a solution containing the template N-boc-l-phenylalanine and functional acrylic monomers at varying ratios with a cross-linker and initiator in a porogenic solvent. This solution was then spin-coated onto 3-(trimethoxysilyl)propyl methacrylate-functionalised silicon wafers and subsequently the film was photo-polymerised. After template extraction, the film thickness and topography of a methacrylic acid MIP was characterised with atomic force microscopy. A 4-vinylpyridine-MIP thin film was then made by depositing the pre-polymerisation solution on top of the methacrylic acid MIP by spin-coating. Photo-lithographic etching through a gold grid and extraction of non-polymerised solution from under the gold mask yielded a grid-patterned surface, in which two different MIPs alternate with dimensionality at the micro- or submicro-meter scale. Selectivity differences between the two MIP surfaces towards fluorescent template analogue N-dansyl-l-phenylalanine were documented using fluorescence microscopy. This side-by-side comparison on the same thin film allows fast and cost-effective assessment of the two very different MIP selectivities towards various biomolecules.     

A New Challenge:The Information Center

To meet ever-increasing user demands for information, many MiS managers are implementing or investigating the concept of the information center (IC). Rather than a competitor for resources and funds, an IC can become an ally between users and the MIS department.     

加工机会原油面临的挑战:污染物

由于欧佩克石油产量减少、全球政治局势紧张、美国页岩油产量与出口量的增加、可替代中东中质含硫原油和委内瑞拉重质油的原油用量日益增长等因素导致原油市场供应的波动与不确定性,给全球炼油商造成了很大的风险。炼油厂越来越多地购买价格便宜的机会原油,但因机会原油质量较差,在可能获利的情况下,也为炼油厂的加工操作带来了不少问题。主要是原油污染物含量的提高会产生污垢、腐蚀、催化剂中毒、产品不合格等问题,以致抵消了购买便宜低质原油的收益。以美国Bakken与Eagle Ford致密油为例介绍了这些机会原油中的污染物及其含量,以及产生的影响。同时介绍了机会原油中污染物的分析标准和可采用的分析技术。结论认为,炼油厂只有选择合适的原油和采取适当的预防措施,才能利用机会原油在动荡的石油市场中生存下来。     

Adsorption and desorption properties for rhenium using a kind of weak-base anion resin

In this paper,a weak-base resin was adopted to recycle rhenium because of its excellent adsorption and desorption properties for rhenium,while the kinetics and thermodynamics properties of adsorbing rhenium from the rhenium stock solution were systematically investigated.The kinetics investigations confirm that the adsorption process of Re belongs to kinetic control by particle diffusion process and the corresponding reaction rate constant is2.68×10~(-3) s~(-1).Then,the Langmuir and Freundlich models were used to describe the adsorption equilibrium behaviors of Re and the thermodynamics parameters are obtained.The results show that the Langmuir model is the best-fitted model,and the Gibbs free energy change of Re adsorption onto ZS15 weak-base resin is△G~0 =-10.59 + 12.66 T.To verify the weak-base resins for extracting rhenium in industrial application,the column experiments were operated in the spray solution generating by roasting the molybdenum concentrates.The results indicate that the weak-base resins possess excellent adsorptive selectivity for rhenium.and the ammonia solution with low concentration could sufficiently desorb rhenium from the resins.