Shear controlled orientation in injection moulding of starch based blends intended for medical applications

Abstract

Biodegradable polymeric implants are considered to be good alternatives to metallic implants in several temporary applications. Aliphatic polyesters have been extensively investigated and have been employed in several biomedical applications. More recently, biodegradable starch based polymeric blends have also been considered as alternative materials. In this study, the effect of shear controlled orientation injection moulding (SCORIM) on the mechanical properties and degradation behaviour of starch-polylactide and starch-poly(ethylene-co-vinyl alcohol) blends has been investigated and compared with those produced by conventional injection moulding. The changes in these properties has also been studied when using an hydroxyapatite filler to reinforce the polymeric matrixes. The SCORIM processing enhanced the unidirectional mechanical properties substantially. The incorporation of hydroxyapatite into the polymer matrix had a stiffening effect but also reduced the strength and toughness. Generally, the mechanical properties deteriorated substantially in vitro. Reinforcement by hydroxyapatite was found to be less effective than expected in a wet environment.     

Velocity of elastic waves in porous ceramic materials: influence of pore structure

Abstract

A review has been undertaken of recently published data on ultrasonic velocity-porosity for a variety of porous ceramic materials, including information on pore structure. These experimental data have been compared with data calculated using a spheroidal pore model incorporating information on pore volume fraction, shape, and orientation. Good agreement is obtained between experimental and calculated values, especially when fractional porosity is less than about 0·25, even when a single 'effective' pore shape is employed in the calculation. The agreement improves if a different pore shape for each porosity level (point by point analysis) is used. The predictive ability of the spheroidal pore model is thus demonstrated.     

A feature extraction method for galvanized steel sheet powdering rates classification

Abstract

This paper describes a feature extraction method for classifying galvanized steel sheet powdering rates. By combining machine vision with statistics, and using the standard deviation's difference between powdered and normal regions, the range of powdered areas is recognized. The method exhibits a number of interesting features: it uses mathematical statistics for image feature analysis, and develops an effective method for analyzing particle size which cannot be measured by manual detection. The experiment result shows that the correction rate of this method to acquire galvanized steel sheet powdered regions is up to 99%, which satisfies the requirements of the application.     

Plans for the future for the Packaging,Transport, Storage and Security of Radioactive Material Journal

Abstract

The regulatory driven design of radioactive material transportation packages leads package vendors to perform analyses that demonstrate the ability of packages to meet the regulatory requirements. For risk assessment and communication, the analysis of package response to thermal environments that are more severe than those described in the regulations is required. In general, experimental and analytical assessments of casks exposed to thermal insults other than the regulatory environment are performed in the USA by the Department of Energy national laboratories. This paper provides a brief summary of some recent thermal analyses of spent fuel transportation packages exposed to thermal environments different from regulatory standards. The analyses were performed by Sandia National Laboratories under several different projects for multiple customers. These analyses examined the response of spent fuel packages exposed to severe thermal environments different from the regulatory hypothetical accident condition. One assessment determined the response of four generic casks to very long duration engulfing fires. The results from these analyses included fire durations necessary to reach critical temperatures of the fuel and seals. In another assessment, two certified spent fuel casks were analysed for exposure to 1 h pool fires. The height of the cask above the pool was varied to study the effect of the vapour dome on the heating of the casks. Another assessment investigated the effect of offset long duration fires on rail cask performance, which showed that casks can withstand offset fires of much longer duration than the regulatory fire. Other assessments examined the response of packages to thermal environments resulting from propane fires and realistic liquid hydrocarbon fires that included various positions of the transportation rail car in the simulation.     

关于教学空间内的展示设计初探南开大学本科生创新科研“百项工程”

展示,顾名思义,是"以综合物、人、场等要素最佳空间关系为手段,以传达特定信息为目的的展览、演示活动(1)"。由于在特定的环境中,不同于其他纯粹的展示空间,造就了别具特色的教学空间内的展示方式。文章以南开大学主楼为研究对象,重点研究和分析了其流线、灯光、色彩、辅助设施等方面,探讨了教学空间内的展示设计意匠。     

40—THE EQUILIBRIUM DISTRIBUTION OF VEGETABLE PARTICLES IN THE BEARD OF A WORSTED RECTILINEAR COMB

A mathematical model is presented that accounts for the distribution of vegetable particles in the beard of a rectilinear comb. The average advancement of a particle in a particular cross-section is dependent on the proportion of moving fibres and the time for which they move in that section.     

41—THE TRANSFER OF VEGETABLE PARTICLES FROM BEARD TO SLIVER IN WORSTED RECTILINEAR COMBING

Vegetable particles found in rectilinear-combed top appear to originate largely from a region near the front of the top comb. From here and elsewhere, their transfer to the combed sliver seems to be dependent on the proportion of the number of fibres in transit and on how firmly they are held. A simple mathematical theory is presented that supports this view. The transfer of neps to combed sliver is also dependent on these factors and on whether they have a fibre extending from them into the detaching zone according to the nep distributions in the detached tufts, many of them originate from behind the top comb.     

37—THE AIR-FLOW FINENESS OF GREASY WOOL: INTER-LABORATORY TESTS OF A PROPOSED STANDARD PROCEDURE

An account is given of an inter-laboratory trial of a method of measuring the fineness of greasy wool by means of a Wira Air-flow Fineness Meter. Eight laboratories took part in two tasks: firstly, a calibration by each laboratory of its own air-flow meter in terms of internationally standardized wools; and, secondly, the measurement of the fineness of greasy-wool core samples by means of the specified method, which included a normal laboratory washing of the wool followed by opening on a wool-type Shirley Analyser.

As a result of the trial, the method was considered to be suitable for use by testing authorities, and tentative limits of precision of the method of measuring the fineness of greasy wool were established. The mean difference between any two laboratories ranged from 0.2 μm at 20-μm diameter to 0.5 μm at 28-μm diameter. This does not include sampling errors.     

12—A CRITIQUE OF SOME HYPOTHESES RELATING TO THE HETEROGENEITY OF THE HIGH-SULPHUR PROTEINS OF WOOL

Joubert and Burns prepared a large number of fractions from the high-sulphur proteins of wool and estimated their molecular weights and amino-acid compositions. Their data have been re-examined in order to look for statistically significant interrelations between amino acids and between the proportion of various amino acids and molecular weight. Statistical analysis of the data is also used to examine the credibility of some hypotheses concerning the mechanism of keratin biosynthesis and to provide further evidence for the existence of families of proteins within the high-sulphur fractions of wool.     

27—THE ANALYSIS OF LIPID-BASED WOOL LUBRICANTS AND SOLVENT EXTRACTS FROM WOOL BY THIN-LAYER CHROMATOGRAPHY

An account is given of a study made by means of thin-layer chromatography of six lipids of the types that may be present in wool lubricants. Residual grease (fatty-matter extract from scoured wool) was also examined. It was found that, by developing a series of chromatograms with solvents differing in polarity, the lipids could be identified. Residual grease did not interfere with the resolution.