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Surface damages caused by the impact of flying objects are important factors responsible for fatigue performance degradation of high-speed railway axles, both qualitative and quantitative assessment of these damages are necessary for the maintenance of these axles. In this paper, cubical projectiles were used to reproduce actual damages on S38C axle specimens by a compressed-gas gun at varying velocities. Morphologies of simulated impact damages were characterized, and fatigue strengths of specimens under different impact damages were determined by the step-loading method. Results show that fatigue strength of impacted specimens reduces with the increase of damage depth; besides, other factors, including damage orientation, damage shape, and microstructural damage also exert their contributions. Finally, evaluation on fatigue strength reduction has been performed based on the damage tolerance philosophy.

AC withstand voltage test is the most severe, the most direct and the most effective test method of judging the XLPE Power Cable insulation Conditioning, It is of decisive significance in determining weather the Power Cable is measured up. Traditional test transformer is bulky, it requires high-capacity of power supply when it is used in AC withstand voltage test of high-capacity Power Cable. This paper adopted the Frequency Conversion Series Resonance Technology in 220kV Cable Withstand Voltage test program and accomplished the test successfully, Greatly reduced the capacity of the power test equipment, it also helps to promote the test quality and the work efficiency, which proved the feasibility and effectiveness in the long-distance high-voltage XLPE cables grade AC voltage test with the Frequency Conversion Series Resonance Technology.

OBJECTIVES This study investigated the relation between biomechanical properties of the proper hepatic artery and sex in pigs and humans to provide the theoretical basis for selecting suitable donor in pig-to-human liver xenotransplant. MATERIALS AND METHODS The proper hepatic arteries of 32 Chinese Hubei white pigs (8 males, 8 females, 8 castrated males, and 8 ovariectomized females) and 10 deceased donors (5 human men, 5 human women) were obtained. The pressure-diameter relations of the proper hepatic arteries were measured on biomechanical test equipment to calculate the incremental elastic modulus (Einc), pressure-strain elastic modulus (Ep), volume elastic modulus (Ev), and compliance. Each sample was sliced into 5-μm frozen sections and stained with hematoxylin-eosin. RESULTS There were significant differences in Einc (F=10.24; P = .001), Ep (F=3.75; P = .001), and Ev (F=3.41; P = .002) of the proper hepatic arteries of female, male, and gonadectomized pigs; females had the lowest elastic modulus and the gonadectomized group had the highest (P < .01). There was a significant difference in compliance of the porcine proper hepatic arteries between the sexes, highest in the female group and lowest in the gonadectomized group (P < .01). No difference in the elastic modulus and compliance of the proper hepatic artery between the male pig and the human man. There was no difference between the female pig and the human woman. CONCLUSIONS There were differences in the biomechanical properties of the proper hepatic arteries of the female, male, and gonadectomized pigs. The biomechanical properties of the human men/women proper hepatic artery match those of the porcine male/female hepatic artery. The correlation between sex and biomechanical properties of the proper hepatic artery in pigs could imply that a pig of the same sex should be chosen for pig-to-human liver xenotransplant.

To obtain the biomechanical and morphological remodelling of hepatic arteries in swine with portal hypertension. A number of 20 white pigs was used, of which 14 were subjected to liver cirrhosis and portal hypertension (PHT) induced by carbon tetrachloride and pentobarbital; the rest were used as the control group. The biomechanical remodelling of the hepatic arteries was measured, namely, the incremental elastic modulus (E inc), pressure–strain elastic modulus (E p), volume elastic modulus (E v), the incremental compliance (C), the opening angle and the stained microstructural components of the vessels. The percentages for the microstructural components and the histologic data significantly changed in the experimental group, three incremental elastic moduli (E inc, E p, and E v) of the experimental group were significantly larger than those of the control group (P

Background: This study aims to obtain the biomechanical properties of ascending aorta and pulmonary trunk between healthy humans and pigs of different months, so as to provide necessary biomechanical experimental basis for anastomosing blood vessel in pig-to-human heart xenotransplantation. Methods: Ascending aorta and pulmonary trunks of the six deceased donors (male 4, female 2) and 42 Chinese Hubei white pigs aged 1–7 months were performed biomechanical test. The blood vessel was given periodic permanent loading and unloading, and repeated force-deformation data were obtained. The elastic properties of the blood vessels were obtained by curve from experimental data. Results: The biomechanical material constant of ascending aorta and pulmonary trunk of pigs did not increase with the increase of age (F = 14.569, P = 0.126). The biomechanical material constant of humans was basically similar to that of pigs aged 1–7 months (F = 12.264, P = 0.225). The elastic modulus was the biggest in pigs aged 7 months in comparison with that in other ages (F = 27.425, P = 0.032). There was no significant difference of elastic modulus of corresponding blood vessel between humans and pigs of different months (F = 17.328, P = 0.215). Conclusions: Our present study suggests that there was no significant difference of elastic properties of ascending aorta and pulmonary trunks between humans and pigs. From biomechanical aspects, anastomosis of corresponding ascending aorta and pulmonary trunks in the process of pig-to-human heart xenotransplantation may be feasible.

To obtain the morphological and biomechanical remodeling of portal veins in swine with portal hypertension (PHT), so as to provide some mechanical references and theoretical basis for clinical practice about PHT.Twenty white pigs were used in this study, 14 of them were subjected to both carbon tetrachloride- and pentobarbital-containing diet to induce experimental liver cirrhosis and PHT, and the remaining animals served as the normal controls. The morphological remodeling of portal veins was observed. Endothelial nitric oxide synthase expression profile in the vessel wall was assessed at both mRNA and protein level. The biomechanical changes of the hepatic portal veins were evaluated through assessing the following indicators: the incremental elastic modulus, pressure-strain elastic modulus, volume elastic modulus, and the incremental compliance.The swine PHT model was successfully established. The percentages for the microstructural components and the histological data significantly changed in the experimental group. Endothelial nitric oxide synthase expression was significantly downregulated in the portal veins of the experimental group. Three incremental elastic moduli (the incremental elastic modulus, pressure-strain elastic modulus, and volume elastic modulus) of the portal veins from PHT animals were significantly larger than those of the controls (P0.05), whereas the incremental compliance of hepatic portal vein decreased.Our study suggests that the morphological and biomechanical properties of swine hepatic portal veins change significantly during the PHT process, which may play a critical role in the development of PHT and serve as potential therapeutic targets during clinical practice.

Strained-Si technology is the Holy Grail for present semiconductor industry and is used extensively to boost the device performance, recently. However, the limitation of strained-Si technology has greatly perplexed us and need to investigate in detail. In this work, the low temperature ballistic measurement enables us to discriminate the origin of mobility enhancement under stress from the reduction of effective mass and/or the influence of different scattering mechanisms. It is found that the electron mobility enhancement under stress will become less sensitive when the gate length of device reaches ∼100 nm. The real mechanism of this phenomenon have be proved to the characteristic of device ballistic transport and the optimal stress design developed in this work can further extend the limitation of Strained-Si technology to the smaller gate length region (technology node) (Fig. 1).

Myelodysplastic syndromes (MDS) are a heterogeneous group of myeloid neoplasms. Chromosomal abnormalities have been detected in 40-70% patients with primary MDS and are heterogeneous among patients of different races and from different backgrounds. In the current study, 351 Chinese adult patients with primary MDS were retrospectively analyzed for their chromosomal abnormalities by karyotyping. Among the 237 cases (67.5%) of chromosomal abnormalities, 99 were copy number changes alone (41.7%), 70 were structural abnormalities alone (29.5%), and 68 displayed both of these changes (28.8%). Over- all, the frequency of −5/5q−/del(5)(q13-33) was 5.1% in these Chinese MDS patients, which was lower than that in the MDS patients of western countries (8.7-23.4%), and the incidence of 5q− syndrome was only 0.3% in Chinese MDS patients. On the other hand, the frequencies of trisomy 8 (19.1%) and −20/20q−/del(20)(q11-13) (9.4%) were higher than those in western countries (1.2-7.0% and 2.0-3.5%, respectively). Chromosomal translocations were also detected in 31 cases (13.1%) including 12 rare translocations that have not been reported in MDS patients before. In addition, i(17)(q10) was detected in nine cases (3.8%), of which six cases only had this single abnormality. According to the IPSS chromosomal prognostic classification, the incidence of poor-risk karyotypes increased in the advanced WHO subtypes (p < 0.001). Together, we detected the unique cytogenetic features of chromosomal abnormalities and some rare translocations of MDS among Chinese patients.