Unconventional fractional quantum Hall effect in monolayer and bilayer graphene

The commensurability condition is applied to determine the hierarchy of fractional fillings of Landau levels in monolayer and in bilayer graphene. The filling rates for fractional quantum Hall effect (FQHE) in graphene are found in the first three Landau levels in one-to-one agreement with the experimental data. The presence of even denominator filling fractions in the hierarchy for FQHE in bilayer graphene is explained. Experimentally observed hierarchy of FQHE in the first and second Landau levels in monolayer graphene and in the zeroth Landau level in bilayer graphene is beyond the conventional composite fermion interpretation but fits to the presented nonlocal topology commensurability condition.     

Effect of Vortex Finder Diameter on Flow Field and Collection Efficiency of Cyclone Separators

In this study, aerocyclone separators, with five different vortex finder diameters are simulated using commercially available computational fluid dynamics code Fluent 6.3.26 to analyze flow field pattern and the collection efficiency. It is found that a decrease in vortex finder diameter results in an increase in pressure drop by 47.84% and an increase in the collection efficiency by 9.54%, whereas, the increase in vortex finder diameter leads to a reduction in pressure drop by 23.87% and a decrease in the collection efficiency by 7.70% as compared to the Stairmand high efficiency cyclone. It is also observed that a decrease in vortex finder diameter leads to about 33% increase in axial velocity and about 25% increase in tangential velocity, whereas, an increase in vortex finder diameter results in about 23% decrease in axial velocity and about 12% decrease in tangential velocity as compared to the Stairmand high efficiency cyclone.     

Editorial - Asia Pacific Microwave Conference 2007 (APMC'07)

The Asia Pacific Microwave Conference was first convened in New Delhi in 1986 and then in Beijing in 1988. It was established to foster a close dialogue among engineers and academia in various applied electromagnetic disciplines inside and outside the Asia Pacific Region. It was also designed to serve as a conduit for channelling advanced technologies into the region, in particular, the developing countries. Starting from the fourth one held in 1992 in Sydney, APMC has been held annually throughout the major cities in the region. Thus after APMC'07 held in Bangkok in December 2007, the APMC series of annual conferences continues its successful run at scheduled dates and venues in the Asia Pacific region: APMC'08 in December 2008 in Hong Kong; APMC'09 in December 2009 in Singapore, APMC'10 in Yokohama, Japan; APMC'11 in Melbourne, Australia and APMC'12 in Taipei, Taiwan.     

Effects of loading frequency and environment on delamination fatigue crack growth of CFRP

The delamination fatigue crack growth was investigated with two kinds of unidirectional CF/epoxy laminates. In the T300/3601 laminate, Mode I crack growths in air were cycle dependent, while it was time dependent in water, and the growth rate in water was lower than that in air. Mode II crack propagation rate either in air or in water was also constant with crack extension, and the crack growth was time-dependent. The crack propagation rate in water was faster than that in air, and it increased with prior-immersion period in water. In the M40J/2500 laminate either in air or in water, Mode I delamination fatigue crack growth was cycle-dependent, and the growth rate in water was lower than that in air. Mode II crack propagation rate either in air or in water was almost constant with crack extension, and the crack growth was cycle-dependent. The crack propagation rate in air was almost identical to that in water.     

Research performance in key medical universities in China observed from the scientific productivity

Research activities in the life sciences during the past few years, have increased appreciably in China, both in regard to relative output of publications and in their impact on the international research community. The purpose of this study is to analyze and evaluate quantitatively the scientific productivity of key medical universities in China by using CBMdisc, MEDLINE and SCI databases. The results showed that Tongji Medical University ranks first in terms of paper output in Chinese and in English languages, while Beijing Medical University is placed second in output but is first in citation impact. Shanghai Medical University had the top annual paper output per scientist, with 2.53 papers in Chinese and 0.13 papers in English. The results also showed that the coverage of Chinese biomedical publications by western indexing services is very poor.     

The influence of low atmospheric pressure on carbon monoxide of n-heptane pool fires

Qualitative theoretical analysis about air pressure influence upon the gas concentration of a fire plume was given, different scale n-heptane pool fires were conducted in a small and a standard compartment room in Lhasa and Hefei, respectively. The experimental results show that, in Lhasa, the average mass burning rates in the small room and the standard room both decrease, burning time increases at about 53% in small room and 45% in standard room more than in Hefei. Whereas for maximum changes of CO concentration, in the small room, in Lhasa, CO concentrations reach about twice bigger peak values at larger increase rates than in Hefei. While in the standard room, in Lhasa and Hefei, there are no significant changes for CO concentration, which agrees well with the theoretical analysis results.     

Microbial stability evaluation of cement-based waste forms at different waste to cement ratio

An evaluation of the effect of differences in chromium nitrate to cement ratio on the microbial stability of a chromium nitrate/cement waste form, as reflected in the leaching of chromium, calcium, magnesium and aluminum; was carried out in this study. An increase in the proportion of chromium in the waste form from 4.8 to 8.7% had no noticeable effect on microbial stability, with the total chromium leached essentially unchanged. Further increases in the proportion of chromium in the waste form from 8.7 to 10.7%, and from 10.7 to 15.9% resulted in a substantial decrease in microbial stability, with 3-fold and 1.3-fold increase in the total chromium leached, respectively, observed. For calcium, increases in the chromium proportion were accompanied with increases in the total calcium leached even though the increases were not in direct proportion to the increases in chromium proportion. For magnesium and aluminum, increases in the proportion of chromium within the range 4.8-10.7% were accompanied with increases in the total respective metals leached, with minor variation for each metal. On the whole, the maximum percentage chromium leached from the different waste forms was substantially lower than those of the other metals.     

In vivo and in vitro tracking of erosion in biodegradable materials using non-invasive fluorescence imaging

The design of erodible biomaterials relies on the ability to program the in vivo retention time, which necessitates real-time monitoring of erosion. However, in vivo performance cannot always be predicted by traditional determination of in vitro erosion, and standard methods sacrifice samples or animals, preventing sequential measures of the same specimen. We harnessed non-invasive fluorescence imaging to sequentially follow in vivo material-mass loss to model the degradation of materials hydrolytically (PEG:dextran hydrogel) and enzymatically (collagen). Hydrogel erosion rates in vivo and in vitro correlated, enabling the prediction of in vivo erosion of new material formulations from in vitro data. Collagen in vivo erosion was used to infer physiologic in vitro conditions that mimic erosive in vivo environments. This approach enables rapid in vitro screening of materials, and can be extended to simultaneously determine drug release and material erosion from a drug-eluting scaffold, or cell viability and material fate in tissue-engineering formulations.     

Investigation of collaborative research trends in Indian medical sciences: 1900–1945

The decade beginning 1925 is important in the history of medical science in modern India. This is evident from the bibliometric study of the publications in theIndian Medical Gazette, from 1900 to 1945. The paper studies the evolution of collaboration in the field of medical sciences during this period. In order to do so the study determines the: (i) pattern of collaboration in basic and applied research in medical science; (ii) trends in the multiplicity of authors; and (iii) the type of collaboration for the period 1900–1945. The collaborative and authorship trends discussed in the paper suggests that medical science was still in the developing stage in India in the period 1900–1945, and there was a possibility of its expansion in the near future.     

铝合金的动态再结晶

本文展现了当前铝及铝合金动态再结晶研究的一些进展。分析了铝合金动态再结晶的特点和材料状态,形变条件对动态再结晶的影响。指出了铝合金动态再结晶研究在理论,实际生产中的意义和铝合金动态再结晶研究的方向。     

21世纪之初工程哲学在东西方的同时兴起

科学哲学和技术哲学都是首先在欧美国家兴起的,可是,工程哲学却是于21世纪之初在中国和欧美发达国家同时兴起和基本同步发展的。文章简要介绍了2002年以来工程哲学在中国和欧美国家发展的重要事件和已经发表的重要著作,最后,简要评论了东、西方工程哲学发展的主要特点。     

Gene expressions of Collagen type I,ALP and BMP-4 in osteo-inductive BCP implants show similar pattern to that of natural healing bones

Osteo-inductive materials give rise to ectopic bone formation in vivo either in muscles or in subcutaneous tissue. However, the underlying molecular mechanism is totally unclear. To investigate the expression pattern of bone related genes in osteo-inductive materials, we performed quantitative PCR (qPCR) to detect the expressions of type I collagen, alkaline phosphatase (ALP) and bone morphogenetic protein 4 (BMP-4) in biphasic calcium phosphate (BCP) ceramics implanted in dorsal muscle of dogs. Bone formation in mandibular alveolus defects served as controls showing the expression patterns of these genes in natural healing bones. Histological examinations were performed to show the bone formation in osteo-inductive BCP implants. Data of qPCR indicated that all tested genes had a similar expression pattern with two peaks during the bone formation either in BCP implants or natural healing bones. Type I collagen and ALP were expressed at lower levels with delayed peak in BCP implant than that in natural healing bone. Higher BMP-4 expression level was detected in BCP ceramic implant than in natural healing bone at all the time points. These results demonstrated that expression patterns of bone-related genes in the inductive bone formation are similar to that of natural healing bone formation. As these three genes are important parameters for osteoblast activity in bone formation, our data provide clue to uncover the molecular mechanism of bone formation in osteo-inductive materials.     

我国随机振动研究近10年来的进展

本文回顾了中国振动工程学会随机振动专业委员会成立后的10年间我国学者在随机振动领域所进行的理论、应用技术研究方面取得的一些重要进展,着重介绍了随机非线性响应时域积分方法与空间有限元结合的随机动力有限元方法的发展;对随机振动与其它相关学科的交叉渗透进一步发展的前景也作了展望.     

Biosynthesis of silver nanoparticles in collagen gel improves their medical use in periodontitis treatment

Silver nanoparticles (AgNP) suspensions were biosynthesized by silver ions reduction in the presence of collagen, a nontoxic, organic polymer, intending to improve their medical use in periodontitis treatment. Spectrophotometric measurements showed a time- and concentration-dependent increase of AgNP formation in each suspension variant. Transmission electron microscopy revealed spherical morphology of AgNP in collagen and their mean diameter size was around 30?nm. The particle size distribution and zeta potential values of AgNP in collagen were determined by dynamic light scattering measurements. The surface charge of AgNP in collagen was positive, while commercial AgNP stabilized in citrate had negative surface charge. In vitro cytotoxicity testing of AgNP in collagen showed that they were biocompatible with human gingival fibroblasts in a wider range of concentrations than commercial nanoparticles. The antibacterial activity of AgNP in collagen against two pathogenic strains present in the periodontal pocket was dose-dependent and higher than that of AgNP in citrate. All these results demonstrated that AgNP prepared in collagen gel had improved properties, like small diameter, positive surface charge, high biocompatibility in human gingival fibroblasts, efficiency against bacterial growth and, thus, better therapeutic potential in periodontal disease treatment.     

线切割单晶硅表面损伤的研究

利用台阶仪、扫描电镜（ＳＥＭ）和Ｘ射线双晶衍射仪,研究了线切割硅片和内圆切割硅片的表面切割损伤和损伤层厚度。实验指出线切割硅片表面粗糙度大,外表面损伤大,但损伤层的厚度要小于常规内圆切割硅片。初步讨论了影响线切割硅片表面损伤的原因     

Phenomenological features of diaphragm discharge

Flame formations of relatively little-studied diaphragm discharge in water at low energy of discharge (up to 10 J) are investigated. Its particular features show up in the fundamental difference in shape between the anode and cathode flames on both sides of the diaphragm, in the difference in variation of their shape and size with the variation of electrical conductivity of the medium, in polar development of flames from the diaphragm to their electrodes, in the possibility of existence of “half-breakdowns”, and in the difference between them depending on polarity, in a special form of cathode breakdown.     

Radon in workplaces: first results of an extensive survey and comparison with radon in homes

Extensive radon surveys have been carried out in many countries only in dwellings, whereas surveys in workplaces are rather sparse and generally restricted to specific workplaces/activities, e.g. schools, spas and caves. Moreover, radon-prone areas are generally defined on the basis of radon surveys in dwellings, while radon regulations use this concept to introduce specific requirements in workplaces in such areas. This approach does not take into account that work activities and workplace characteristics can significantly affect radon concentration. Therefore, an extensive survey on radon in different workplaces have been carried out in a large region of Italy (Tuscany), in order to evaluate radon distribution in workplaces over the whole territory and to identify activities and workplace characteristics affecting radon concentration. The results of this extensive survey are compared with the results of the survey carried out in dwellings in the same period. The workplaces monitored were randomly selected among the main work activities in the region, including both public and industrial buildings. The survey monitored over 3500 rooms in more than 1200 buildings for two consecutive periods of ～6 months. Radon concentration was measured by means of passive nuclear track detectors.     

Crystallization rules of calcium oxalate crystals in lithogenic urine and in healthy urine in vitro

Crystallization of calcium oxalate (CaOxa) was comparatively studied in vitro in diluted lithogenic urine and in diluted healthy urine by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy. In healthy urine, the crystallization was a growth-controlled process in the early stage of crystallization and a nucleation-controlled process in the middle and late stage. However, the crystallization of CaOxa was always a growth-controlled process in the lithogenic urine. That is, the size of CaOxa particles grow gradually and at last large size of CaOxa stones formed. Comparing the CaOxa crystals grown in lithogenic urine and in healthy urine, three differentiations were observed. First, the average particle size of CaOxa crystals precipitated in lithogenic urine is larger than that in healthy urine. Second, the morphology of calcium oxalate monohydrate (COM) crystals changes from sharp hexagonal in lithogenic urine to round and blunt in healthy urine. Third, calcium oxalate dihydrate (COD) crystals were induced in healthy urine. The results in this study may provide important clues to cure urinary stones.     

An analysis of the reasons for the reduction in reliability of machinery structures under low temperature climate conditions

The influence of low temperature on the reliability of machine parts and on the characteristics of strength of steels and their weld joints is analyzed. It is established that a drop in temperature in impact cyclic loading causes a decrease in fatigue resistance of weld joints of low-alloy steels and a corresponding increase in relative frequency of crack formation in them. A comparison of experimental and service data shows that the increase in service relative frequency of crack formation in welded machine parts at reduced temperature is an indication of their fatigue origin. It was concluded that the increase in the frequency of failures of welded machine parts with a reduction in temperature observed under service conditions is caused by a reduction in their fatigue resistance and an increase in the tendency of their materials toward brittle fracture.     

AutoCAD与Word和Excel图文转换的效果处理

AutoCAD计算机辅助设计软件、Word字处理软件和Excel电子表格处理软件得到了极为广泛的应用，但Word本身能绘制图形的能力很有限，用于绘制标准的工程图则更难。而使用AutoCAD绘图时，要写入大量的文本和表格也十分不便，利用Word或Excel处理软件的特点写入文字或表格，然后插入到AutoCAD绘图文件中，会取得意想不到的效果。针对在AutoCAD与Word和Excel图文转换过程中存在的问题进行了深入探讨，从而完善了工程文件中不同软件的协同设计。