Effects of Pre-Deformation on Electrochemical Behavior of AISI304 Stainless Steel

AbstractEffect of pre-deformation on corrosion behavior of AISI 304 stainless steel was investigated by electrochmeical measurements, and the influence factors were chacterized by microstructural analysis and electron backscattering diffraction (EBSD). The results of polarization curves and electrochemical impedance spectroscopy indicated that corrosion resistance decreased 15%-20% after 20% pre-deformation. The reason may be due to the martensite transformation and the pile-up of dislocation according to the change of the microstructure. EBSD displays that an increase in grain orientation of austensite and martensite is another factor leading to the decrease of corrosion resistance. Besides corrosion resistance can also be reduced by the increase of the variety and fractions of texture. While corrosion resistance increases because of the increase of low angle boundaries

COMPARISON OF SOME BIOMECHANICS PARAMETERS OF BREASTSTROKE SWIMMERS IN FLUME AND SWIMMING POOL

The purpose of this study was to compare some parameters of breaststroke swimmers in a swimming pool with those for breaststroke swimming in the flume, to search whether there is some difference between two test circumstances of swimming pool and flume in technical parameters. Four male breaststroke swimmers aged between16 and 18 years were studied. Subjects were required to swim in a 25m pool for best or familiar stroke length and tried to decrease stroke rate, and performed at three minute intervals at speeds ranging from 70% to 100% of the best performance of individuals. Subjects were familiarized to flume swimming on the day prior to be tested, then swam at the same speed based upon conversion from pool in swimming flume. According to testing we found that stroke rate, stroke length and efficiency index for pool and swimming flume at corresponding speeds were similar. Of course, there was as expected significant difference in the stroke rate and stroke length used between subjects to swim at the various speeds

A CASE STUDY: EVALUATING THE DIFFERENCE OF TECHNIQUE BY USING EFFICIENCY INDEX IN ELITE MALE FREESTYLE SWIMMERS

The purpose of the study was to evaluating the difference of technique by using efficiency index in elite male freestyle swimmers during their training periods. Two swimmers were selected to take a 6 x 50 m freestyle descend set in a 50 m swimming pool. The mean velocity (MV), stroke length (SL), stroke cycle (Se), efficiency index (El) and concentration of blood lactate (BL) were measured and compared to illuminate the difference of swimming technique and its impact on the performance level. According to previous and present studies, efficiency index is a useful measurement to evaluate the efficiency of the technique of swimmers. From limited number of subjects in the study, we speculated that the most effective intensity of improving efficiency of swimming technique is a little bit higher than anaerobic threshold

Understanding Transport of an Elastic, Spherical Particle through a Confining Channel

The transport of soft particles through narrow channels or pores is ubiquitous in biological systems and industrial processes. On many occasions, the particles deform and temporarily block the channel, inducing a built-up pressure. This pressure buildup often has a profound effect on the behavior of the respective system; yet, it is difficult to be characterized. In this work, we establish a quantitative correlation between the built-up pressure and the material and geometry properties through experiments and mechanics analysis. We fabricate microgels with a controlled diameter and elastic modulus by microfluidics. We then force them to individually pass through a constrictive or straight confining channel and monitor the pressure variation across the channel. To interpret the pressure measurement, we develop an analytical model based on the Neo-Hookean material law to quantify the dependence of the maximum built-up pressure on the radius ratio of the elastic sphere to the channel, the elastic modulus of the sphere, and two constant parameters in the friction constitutive law between the sphere and the channel wall. This model not only agrees very well with the experimental measurement conducted at large microgel deformation but also recovers the classical theory of contact at small deformation. Featuring a balance between accuracy and simplicity, our result could shed light on understanding various biological and engineering processes involving the passage of elastic particles through narrow channels or pores

Active Shape Control and Phase Coexistence of Dielectric Elastomer Membrane With Patterned Electrodes

Various applications of dielectric elastomers (DEs) have been realized in recent years due to their lightweight, low cost, large actuation and fast response. In this paper, experiments and simulations are performed on the active shape control of DE structures with various two-dimensional patterned electrodes by applying voltage. A DE membrane with a pattern of electrodes is mounted on an air chamber. It is first inflated by air pressure and then further deformed by applying voltage, which actively controls the membrane shape. Under higher voltage, an acrylic membrane with larger actuation can induce shape instability and demonstrate multiphase coexistence behavior. In the framework of electromechanical theory, finite element simulations are carried out and the results are in good agreement with those obtained by experiments

Herbivores Alleviate the Negative Effects of Extreme Drought on Plant Community by Enhancing Dominant Species

Aims Both extreme drought and insect herbivores can suppress plant growth in grassland communities. However, most studies have examined extreme drought and insects in isolation, and there is reason to believe that insects might alter the ability of grasslands to withstand drought. Unfortunately, few studies have tested the interactive effects of extreme drought and insect herbivores in grassland communities. Methods Here, we tested the drought–herbivore interactions using a manipulative experiment that factorially crossed extreme drought with the exclusion of insect herbivores in a temperate semiarid grassland in Inner Mongolia. Important Findings Our results demonstrated that both extreme drought and insect herbivores separately decreased total plant cover. When combined, insect herbivores reduced the impact of drought on total cover by increasing the relative abundance of drought-resistant dominant species. Our results highlight that the negative effect of extreme drought on total plant cover could be alleviated by maintaining robust insect herbivore communities

Transcriptome-based Discovery of AP2/ERF Transcription Factors Related to Terpene Trilactones Synthesis in Ginkgo biloba

Ginkgo biloba is a unique tree in China with medicinally and phylogenetically important characteristics. Terpene trilactones (TTL) is a key active pharmaceutical ingredient in Ginkgo, so the content of TTL in Ginkgo has become one of the important indices for evaluating quality of the medicinal materials. By transcriptome sequencing on samples treated by chlormequat, ultraviolet (UV) and drought, totally 59820 contigs and 37564 unigenes were obtained. Furthermore, 18234 unigenes were annotated through COG, KEGG and GO analysis. There were 78 AP2/ERF transcription factors, 23 factors of up-regulation and 66 factors of down-regulation that were related with synthetic pathway of TTL in Ginkgo. Phylogenetic tree clustering analysis indicated that there were 42 AP2s could be clustered into ERF, DREB and RVA subfamilies. EMSA analysis demonstrated that GbERF13, GbERF25 and GbERF27 could bind with regulatory elements, such as E-box, in the upstream of GbMECPs promoter. Expression analysis showed that the expression level of GbERF25 was the highest in root, and GbERF25 and GbERF27 were expressed in relatively high transcription levels in leaf and other tissues. The results of qRT-PCR indicated that CCC treatment could significantly improve expression levels of ERF25 and ERF27, and UV and drought could induce transcription levels of ERF13 and ERF25, respectively. The results implied that ERF25 and ERF27 might involve in the induction and regulation of CCC treatment on synthesis of bilobalide in G. biloba. ERF13 might participate in the regulation of bilobalide synthesis induced by UV, and EFR25 might involve in the regulation of the synthesis induced by drought. During annual cycle of expression, the transcription levels of ERF13, ERF25 and ERF27 had significantly positive correlation with diterpene level with correlation coefficient 0.975. It implied that these transcription factors mainly acted on the MEP pathway that regulated synthesis of bilobalide. The aim of the research was to indicate the mechanism of environment or cultivation measure regulating target gene of TTL metabolic pathway by AP2/ERF, and establish metabolic network of AP2/ERF regulating TTL synthesis