Hazard evaluation of organic peroxides

A comprehensive study on the hazard characteristics of organic peroxides was made with a view towards identifying the type of tests that might be usefuResults obtained from the various tests performed indicate that these tests clearly delineate the relative hazards of the peroxides investigated. It ap     

A set of pathological tests to validate new finite elements

The finite element method entails several approximations. Hence it is essential to subject all new finite elements to an adequate set of pathological tests in order to assess their performance. Many such tests have been proposed by researchers from time to time. We present an adequate set of tests, which every new finite element should pass. A thorough account of the patch test is also included in view of its significance in the validation of new elements.     

Drug Dissolution Testing: Today and Tomorrow

This article discusses the present role of dissolution tests both in terms of current compendial requirements and the use of such tests by the pharmaceutical industry.

Insofar as future use is concerned, the suggestion is made that the compendia clearly distinguish between those monographs where dissolution tests have been shown to be of biological significance (i.e., Digoxin Tablets) and those which are simply acting as physical quality control procedures. Logically, a dissolution test should be applied to all solid dosage forms, although from a logistical point of view it might be appropriate to confine this requirement, at least initially, to those drugs having an aqueous solubility of 0.5 per cent or less.

In the future, the pharmaceutical industry should expand its use of dissolution testing both in formulation development and production control, with a view to establishing, in as many instances as possible, dissolution tests having biological significance, i.e., where reliable in vitro - in vivo correlations have been established.     

Utilization of municipal solid waste incineration (MSWI) fly ash in blended cement Part 2. Mechanical strength of mortars and environmental impact

This second of two articles dealing with the utilization of MSWI fly ash in blended cement studies the effects of two variants of the stabilization process on the behavior of the treated fly ash (TFA) introduced into cement-based mortars. From a technological point of view, the modifications of the process are very efficient and eliminate the swelling produced by the introduction of MSWI fly ash in cement-based mortars. TFA has a significant activity in cement-based mortars and can also advantageously replace a part of the cement in cement-based material. From an environmental point of view, the results of traditional leaching tests on monolithic and crushed mortars highlight a poor stabilization of some harmful elements such as antimony and chromium. The use of a cement rich in ground granulated blast furnace slag (GGBFS) with a view to stabilizing the chromium is not efficient. Since neither adequate tests nor quality criteria exist to evaluate the pollutant potential of a waste with a view to reusing it, it is difficult to conclude on the environmental soundness of such a practice. Further experiments are necessary to investigate the environmental impact of TFA introduced in cement-based mortars depending on the reuse scenario.     

Drug Dissolution Testing: Today and Tomorrow

Abstract

This article discusses the present role of dissolution tests both in terms of current compendial requirements and the use of such tests by the pharmaceutical industry.

Insofar as future use is concerned, the suggestion is made that the compendia clearly distinguish between those monographs where dissolution tests have been shown to be of biological significance (i.e., Digoxin Tablets) and those which are simply acting as physical quality control procedures. Logically, a dissolution test should be applied to all solid dosage forms, although from a logistical point of view it might be appropriate to confine this requirement, at least initially, to those drugs having an aqueous solubility of 0.5 per cent or less.

In the future, the pharmaceutical industry should expand its use of dissolution testing both in formulation development and production control, with a view to establishing, in as many instances as possible, dissolution tests having biological significance, i.e., where reliable in vitro - in vivo correlations have been established.     

Shear strength of polymers and fibre composites: 1. thermoplastic and thermoset polymers

The shear strengths of eight thermoplastics and three DGEBA-based epoxies in sheet form have been tested by the punch and Iosipescu tests. The testing temperatures ranged from 20 to 120°C, and the glass transition temperatures were measured as well. The shear strengths of the epoxies were also estimated from compressive tests on short cylinders. The Iosipescu test gave very unreliable results for polymers in the rubbery state because large deformations were induced before failure, and this caused high tensile stresses to develop instead of high shear stresses. With the punch test the force often had two maxima before failure, and the discs punched out did not have straight sides, so there was also much doubt about the purity of the shear stresses developed. The two methods were often in sharp disagreement. However, they gave comparable results with epoxies tested at room temperature. Comparison with compressive tests indicated that the ratio of compressive yield strength to shear yield strength varied from 1.5 to 2.4. In view of the uncertainties in the tests, compressive testing may be a good method to obtain an approximate value for the shear strength. The Tresca criterion (i.e. divide the compressive yield strength by two to get the shear yield strength) is probably good enough in view of the uncertainties in the shear tests. It works equally well for the ultimate shear strength. A new and better test is clearly needed for the estimation of the shear strength of polymers in sheet form.     

Role of hydrostatic stress in hydrogen diffusion in pearlitic steel

The relevant role of hydrostatic stress in hydrogen diffusion in pearlitic steel is outlined from both theoretical and experimental points of view. The theoretical development offers the formulation of hydrogen diffusion equations where hydrogen flux density depends not only on the concentration gradient, but also on the hydrostatic stress distribution in the sample. The experimental programme consisted of slow strain-rate tests on axisymmetric notched samples at different strain rates under simultaneous hydrogen charging by cathodic polarization. The use of different notch geometries allows a study of the influence on hydrogen diffusion of the hydrostatic stress state in the vicinity of the notch tip. A specific microscopic mode of fracture different from classical cleavage was found, associated with hydrogen effects: the tearing topography surface. In the quasi-instantaneous tests, the value of hydrostatic stress at the sample boundary (just the notch tip) at the failure instant is relevant from the fracture point of view. In the quasi-static tests, the tearing topography surface depth equals that of the maximum hydrostatic stress point, and the maximum value of the stress triaxiality in each geometry (ratio of the hydrostatic to the equivalent stress, almost constant during the tests) seems to govern the diffusion process. These facts emphasize the relevant role of hydrostatic stress in the vicinity of the notch in hydrogen diffusion.     

Statistical discrimination of climate modification by urbanization

The statistical significance of observed changes in precipitation characteristics brought about by urbanization is investigated by using several statistical tests, including bivariatex ²,T ², likelihood ratio and conditional-t tests. Annual precipitation data from a number of stations in the LaPorte, St. Louis, Tulsa and Kansas City areas are analysed and the results are presented. The nature and limitations of these tests are discussed from the view points of assumptions made in the tests and the number of observations needed.     

In vitro corrosion characterization and cell proliferation on surface‐modified Ti

Two types of surface treatments (Low pressure metal organic chemical vapor deposition (Ti‐MOCVD) and anodized Ti) have been conducted on Ti to improve their osteointegration properties in view of dental implant application. The two typologies of surfaces have been characterized in vitro both regarding the corrosion and the in biological behaviour in comparison with the Ti machined surface. The corrosion tests showed that both the surface treatments reduced markedly the corrosion rate compared to Ti machined. The biological tests showed that all specimens are cytocompatible and significant differences among them were detected. In particular WST1 tests showed more viable osteoblasts adhering to MOCVD specimens in comparison with the other surfaces.     

Mechanical Characterisation of Metals by Indentation Tests: An Experimental Verification Study for On‐site Applications

Abstract: Mechanical characterisation techniques have been recently proposed, which use as main information source the geometry of the residual imprint left on metal surfaces by hardness or instrumented indentation tests. Relevant identification procedures have been developed but the problem has been investigated, so far, mainly from a methodological point of view, exploiting pseudo‐experimental data. This contribution presents the results of a verification study based on the real deformation measurements, collected from tests performed at scales consistent with those of structural applications. It is shown that the recovered mechanical properties compare satisfactorily well with those resulting from traditional tensile tests.     

也谈加筋土强度模型与应力─应变特性

本文从加筋作用机理的角度，推导了加筋土强度参数的表达式，并提出了判断加筋土破坏形态的方法，最后以三轴试验成果与理论分析进行了对比，二者吻合较好。     

也谈加筋土强度模型与应力─应变特性

本文从加筋作用机理的角度，推导了加筋土强度参数的表达式，并提出了判断加筋土破坏形态的方法，最后以三轴试验成果与理论分析进行了对比，二者吻合较好。     

带状线法测试辐射骚扰的方法浅析

针对常规天线法辐射骚扰测量中，接收天线的位置和被测件不同极化方向影响测试结果的问题，采用带状线法进行辐射骚扰测试的方法，使辐射骚扰的测试过程更为简单便捷。     

Towards standard tests for abrasion resistance of concrete report on a limited number of tests studied,with a critical evaluation

A comparative study on a limited number of existing abrasion tests for concrete has been done, with the intention that it should serve as a basis for the preparation of a recommendation for a standard test or tests. A summary and classification of the tests is presented, together with a critical evaluation. In view of the number of different tests currently being used in various countries, it is clear that no single test has yet been devised that adequately measures the wear resistance of concrete under all conditions. Since concrete is subjected to different kinds of wear, it seems likely that a number of tests, each suited to a particular mode of abrasion, will be required. Further experimental evidence on the correlation of test data with practical performance is required before firm recommendations can be made. prepared while a temporary visitor at the Building Research Station Technion, Haifa, Israel, January, 1983 Prepared for submission to RILEM CPC-14 Concrete Permanent Committee, June 1984.     

Long-time stregth of polymethylmethacrylate

Experimental data produced by short and long-time strength tests on polymethylmethacrylate (PMMA) specimens supported the view that the time-to-rupture of this material under stress is the time required for a defect (crack) to be formed and grow to a critical size as a result of which instantaneous fracture of the specimen takes place.     

真空荧光显示屏玻板的选用

真空荧光显示屏的外壳通常用浮法玻璃做成，要求有足够的强度。本文从材料力学角度出发，分析真空荧光显示屏的外壳所受的剪切应力，吸收他人的经验，并根据自己的试验，确定真空荧光显示屏中浮法玻璃的容许剪切应力。     

Time and temperature dependent mechanical characterization of polymer‐based materials in electronic packaging applications

Abstract

The thermo‐mechanical testing of high performance polyimide films Type HPPST supplied by Dupont^® was conducted at different strain rates and in different temperature environments. The stress‐strain behavior of materials was investigated, and the dependence of Young's modulus on temperature and strain rate is reported. In view of the uncertainty of the Young's modulus determination, the specimens were tested with unloading‐reloading to verify the test results. Constant strain rate uniaxial tensile tests and long‐time creep tests at various temperatures were performed to characterize the time‐temperature‐dependent mechanical property precisely. Cyclic loading tests were also implemented on specimens to investigate cyclic stress‐strain behaviors. This research is expected to enhance finite‐element‐modeling accuracy and characterize material properties precisely.     

改善乌龙泉矿爆破效果的研究

本文就乌龙泉自云石矿台阶识孔爆破进行了有针对性的瀑破优化研究。通过理论分析、模拟台阶试验得出了较优的孔网面积与分段装药参数，并为现场工业试验所验证，大块率降低了３１．４％。     

改善乌龙泉矿爆破效果的研究

本文就乌龙泉自云石矿台阶识孔爆破进行了有针对性的瀑破优化研究。通过理论分析、模拟台阶试验得出了较优的孔网面积与分段装药参数，并为现场工业试验所验证，大块率降低了３１．４％。