Indentation of materials as a new method of micromechanical testing

The method of local loading (MLL) with a rigid indentor was used for the micromechanical testing of materials. This method enabled the construction of σ-∈ deformation curves, and determination of strength and plasticity characteristics, Young modulus, and work hardening. Considering the earlier described methods to determine fracture toughness, ductile-brittle transition temperature, and anisotropy of mechanical properties, MLL can be viewed as a universal method for investigating the mechanical properties of materials. The mechanical properties of brittle materials (including ceramics), thin coatings, phase components of composite materials and of inhomogeneous structures whose properties vary along the cross-section can be determined only by MLL. Institute for Problems of Materials Science, Ukraine National Academy of Sciences, Kiev. Translated from Poroshkovaya Metallurgiya, Nos. 7–8(408), pp 85–93, July–August, 1999.     

基于激光遥测方法的某在役风电塔现场实测分析

风力发电塔作为一类特殊的高柔结构,顶部支撑的风机在工作状态下对塔身产生动态激励,目前的风电塔振动实测通常采用接触式传感器.为发展风电塔现场非接触测试技术,本文对激光遥测方法进行阐述,利用加速度计和激光遥测设备对某1.5 MW风电塔进行环境脉动激励下的动力实测,对两种仪器的现场使用及测试结果进行对比,分析遥测方法的优势.利用得到的多组实测信号,分别采用峰值拾取法和随机子空间识别法进行分析处理,获得该风电塔的自振频率.     

A new endoscopic method of gastric acid secretory testing

OBJECTIVE: To date, the effect of Helicobacter pylori on acid secretion remains controversial. To evaluate changes in the gastric acid secretory response before and after H. pylori eradication in a large number of patients, we devised a new endoscopic method of gastric acid secretory testing, the endoscopic gastrin test (EGT). METHODS: In EGT, endoscopy was begun 15 min after intramuscular injection of 4 microg/kg tetragastrin. Gastric fluid secreted between 20 and 30 min after gastrin injection was aspirated and collected during endoscopic examination. The amount of acid in the sample collected over this 10-min period was estimated by titration and expressed in H+ mEq/10 min. Fifteen subjects underwent a conventional secretory test using a nasogastric tube (conventional method) and EGT on different days to assess the correlation between results obtained with the two methods. In 10 of these subjects, EGT was repeated under the same conditions to assess its reproducibility. RESULTS: EGT values correlated very well with peak acid output determined by the conventional method (n = 15, r = 0.92) and had high reproducibility (n = 10, CV = 5.6). We noted that EGT takes just a little longer to perform than a routine endoscopic examination, and the influence of an endoscope in the stomach on acid secretion was not present. CONCLUSION: The EGT should be very useful as a rapid, simple substitute for conventional secretory testing when repeated gastric secretory tests are required, especially in investigating the effect of H. pylori on acid secretion in a larger population.     

Electron beam surface modification of a porous bronze-graphite composite

Elemental powders were mixed to obtain a 90 wt pct copper, 8 wt pct tin, and 2 wt pct graphite composite. The porosity level of the sintered specimens was reduced from 25 to 10 pct, which resulted in an increase in the macrohardness value from 17 Hv (90 MPa) to 67 Hv (355 MPa); the density of the sintered specimen was 7.80 g · cm⁻³. The synthesized material was then subjected to electron beam (EB) surface melting. The resultant surface was homogeneous and the microstructural features were refined. The segregation level and variation in the microhardness were drastically reduced. The morphology of the otherwise irregular pores changed to spherical, thereby reducing their interfacial energy. An intriguing modification in the EB melted layer had a density gradient with depth that is sensitive to the heating time of the material using EB. At a heating time of 250 ms, the upper region of the melted layer was dense and hard; the density and the hardness were 8.5 g · cm⁻³ and 103 ± 7 Hv, respectively, while the lower region had density of 6.7 g · cm⁻³ (porosity 22 pct). If the heating time was reduced to 17 ms, the distribution of pores was reversed; the density of upper and lower layers changed to 3.9 and 8.2 g · cm⁻³, respectively. In spite of the higher density of pores, the EB processed composite exhibited increased hardness, compressive strength, and tensile strength. The formation of pores in the lower EB melted region was explained using a qualitative fluid flow model. The combination of a dense substrate and porous surface was desirable, since the former improved the strength and the thermal conductivity of the composite and the latter could be impregnated with oil to achieve the required lubrication levels.     

旋风分离器新型减阻疏导器的实验研究

对加设三种不同尺寸的弧形减阻疏导器的旋风器进行实验研究，推导出弧形减阻疏导器的最佳匹配参数。结果表明：对相同规格的旋风筒，采用合适的弧形减阻疏导器，旋风筒阻降降低约20％～35％，而分离效率仅下降3％～5％。     

Development of a new cellulose triacetate membrane with a microgradient porous structure for hemodialysis

Dialytic performance and biocompatibility of a newly developed cellulose triacetate (CTA) membrane with a microgradient porous structure, produced without using polyvinylpyrrolidone (PVP) and liquid paraffin, were compared with those of a conventional polysulfone (PS) membrane dialyzer. In vitro and clinical results demonstrated no significant difference in the dialytic performance and biocompatibility of the two dialyzers, but the CTA dialyzer lost less albumin during dialysis than the PS. These results suggest that a CTA membrane dialyzer with a porous microgradient structure attained comparable performance and biocompatibility to PS, and the risk of albumin loss was suppressed by the new CTA membrane.     

新型液控自动取样机的研制

基于取样系统现状,以及自动取样机的速度特性和负载特性,提出了一种新型液控自动取样方式,该方式由液压缸驱动取样小车,在输送带出料端,垂直于送料方向取样.利用液压系统调速简便、稳定性好的特点,根据取样量大小,调节取样小车速度,且速度均匀稳定,保证了取样的准确性.该机经试运行,性能良好,为实际系统提供了有价值的新方法.     

Safety testing of a new electronic toothbrush

While there have been major advances in understanding the causes and treatments of the inflammatory periodontal diseases in the past decade, there is still high reliance on the patient to prevent progression of disease through daily oral hygiene, primarily toothbrushing and flossing. A new electronic toothbrush, which produces mild fluid cavitation as well as rapid fluid streaming, has been developed and has shown promise in the ease and efficacy with which it removes plaque. In order to determine the safety of frequent and prolonged use of this device, the gingival tissues of 6 mongrel dogs were exposed to excessively long daily exposures to this toothbrush for up to 2 months. Each quadrant of each dog's mouth was randomly assigned a different treatment: no brushing, manual brush 1.0 minute, electronic brush 1.0 minute, or electronic brush 7.5 minutes. The dogs were examined weekly by a periodontist who was blinded to the treatments. Plaque scores and bleeding on probing scores were calculated, and possible gingival irritation was monitored carefully. At the end of the trial gingival biopsies taken from all the test areas. These were processed for conventional histopathologic evaluation and examined by an oral pathologist who was also blinded as to the treatments. The results showed that brushing a single posterior segment of teeth for 7.5 minutes daily for 2 months with the electronic brush did not result in any clinically or histologically evident damage to the gingiva. Rather, the areas so treated showed excellent health as determined by both clinical and histologic criteria.(ABSTRACT TRUNCATED AT 250 WORDS)     

高比表面多孔材料的制备研究进展

介绍了几种多孔材料的制备方法及原理,包括模板法、沉淀法、溶胶-凝胶法等,并对不同方法的应用做了简要说明,最后对高比表面多孔材料的未来应用前景进行了展望。     

Validation of a capillary electrophoresis method for the enantiomeric purity testing of ropivacaine, a new local anaesthetic compound

A capillary electrophoresis method for the determination of the enantiomeric purity of ropivacaine, a new local anaesthetic compound developed by Astra Pain Control AB, has been validated. The method showed the required limit of quantitation of 0.1% enantiomeric impurity and proved to be robust. Good performances were also shown for specificity, linearity, system repeatability and accuracy. The same capillary electrophoresis method can also be used to simultaneously chirally resolve homologues and impurities of ropivacaine.     

Fallopian tissue sampling with a cytobrush during hysteroscopy: a new approach for detecting tubal infection

This study was designed to evaluate a potentially important source of error in T2-hyperintense lesion measurement unique to longitudinal multiple sclerosis treatment trials that would not be detected by the standard intraobserver and interobserver error analyses. The effect of this "error of serial studies" was tested by using the standard-of-reference manual-outlining approach and a modified bi-feature space (statistical) approach applied to a database of five consecutive patients. To simulate the conditions of a longitudinal treatment trial, each patient had immediate repeat MR studies of the brain with imperfect head repositioning. The study hypothesis was confirmed that with an improved quantitative methodology, the "error of serial studies" (interseries error) would exceed the intraobserver error.