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The effects of trace Ca and Sr addition on dynamic precipitates, dynamic recrystallization (DRX) behavior, and texture evolution of Mg–5Zn alloy sheets fabricated by high strain rate rolling (HSRR) were investigated by electron backscattered diffraction (EBSD), transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS), and X-ray diffraction (XRD). The Zn-rich precipitates formed with plate shapes, short-rod shapes, and near-spherical shapes, indicating that the most important function of adding Ca and Sr is to promote the precipitation process. The precipitate density increases, but the precipitate size and DRX volume fraction decrease with the addition of the alloying elements. It is concluded that the effects of combined Ca/Sr addition on promoting precipitation and refining precipitate size are more effective than that of single Ca addition, and the reduction in DRX volume fraction can be attributed to the inhibition of fine precipitation on the nucleation and growth of DRX. Moreover, the macro-texture intensity is mainly related to DRX as the DRX grains are much more randomly oriented than deformed grains. In addition, the texture intensity in DRX regions is primarily associated with the precipitates, which can inhibit DRX grain rotation due to their pinning effect on the grain boundaries.
The microstructure evolution, dynamic recrystallization (DRX) and precipitation of the ZM61 alloy sheets prepared with different rolling conditions were studied. The DRX grain sizes (dDRX) at four high strain rate rolling (HSRR) temperatures (275–350 °C) are 1.9, 2.3, 2.6 and 3.1 μm, respectively, while the DRX volume fractions (fVDRX) are 69, 73, 76 and 82%, respectively. 300 °C is selected as the optimal HSRR temperature. The dDRX and fVDRX of the alloys prepared by pre-rolling (PR) at 300 °C + HSRR are 1.0 μm and 91%, respectively. The PR treatment does not change the types of the precipitates but promotes the precipitation. The tensile strength (UTS) of 369 MPa and yield strength (YS) of 261 MPa can be achieved by HSRR at 300 °C, while a further increase in both UTS and YS can be obtained by PR treatment.
This study attempts to figure out the seasonality of the transmissibility of hand, foot and mouth disease (HFMD). A mathematical model was established to calculate the transmissibility based on the reported data for HFMD in Xiamen City, China from 2014 to 2018. The transmissibility was measured by effective reproduction number (Reff) in order to evaluate the seasonal characteristics of HFMD. A total of 43 659 HFMD cases were reported in Xiamen, for the period 2014 to 2018. The median of annual incidence was 221.87 per 100 000 persons (range: 167.98/100,000–283.34/100 000). The reported data had a great fitting effect with the model (R2 = 0.9212, P < 0.0001), it has been shown that there are two epidemic peaks of HFMD in Xiamen every year. Both incidence and effective reproduction number had seasonal characteristics. The peak of incidence, 1–2 months later than the effective reproduction number, occurred in Summer and Autumn, that is, June and October each year. Both the incidence and transmissibility of HFMD have obvious seasonal characteristics, and two annual epidemic peaks as well. The peak of incidence is 1–2 months later than Reff.
Residual strain often occurs in metal when it was subjected to the tension load, random vibration, or high impact. The mild steel was selected as the research object, and the feasibility of using nonlinear ultrasonic technique to characterize the residual strain was investigated in this paper. First, the mild steel specimens were stretched to several different kinds of stress, then the nonlinear effect as well as the microstrain of each sample was measured. The results indicate that the microstrain increases with increasing applied stress and reaches a maximum value of about 0.036% as the tensile stress increases to the elastic limit. Compared with the original specimen, the nonlinear parameter of tensile specimen gradually increased within the elastic limit. This result reveals that the variation of nonlinear parameter was related to microstrain in mild steel, because the microstructure observation demonstrated that the dislocation structure was basically unchanged within the elastic limit. This research indicates that the nonlinear ultrasonic method has the promising potential to characterize the microstrain in metals.
A coaxial-output rolled strip pulse-forming line (RSPFL) with a dry structure is researched for the purpose of miniaturization and all-solid state of pulse-forming lines (PFL). The coaxial-output RSPFL consists of a coaxial-output electrode (COE) and a rolled strip line (RSL). The COE is characterized by quasi-coaxial structure, making the output pulse propagate along the axial direction with a small output inductance. The RSL is rolled on the COE, whose transmission characteristics are analyzed theoretically. It shows that the RSL can be regarded as a planar strip line when the rolling radius of the strip line is larger than 60 times of the thickness of the insulation dielectric layer of RSL. CST modeling was carried out to simulate the discharging characteristic of the coaxial-output RSPFL. It shows that the coaxial-output RSPFL can deliver a discharging pulse with a rise time <6 ns when the impedance of the RSL matches that of the COE, which confirms the theoretical analysis. A prototype of the coaxial-output RSPFL was developed. A 49-kV discharging pulse on a matched load was achieved when it was charged to 100 kV. The discharging waveform has a pulse width of 32 ns, with a rise time of 6 ns, which is consistent with the simulation waveform. An energy-storage density of 1.9 J/L was realized in the coaxial-output RSPFL. By the method of multi-stage connection in series, a much higher output voltage is convenient to be obtained.
Disaster can strike people in any community at any time anywhere in the world. Disasters occur with high frequency, take on multiple forms, and exert wide influence, typically causing property damage, injuries, and death. As the world’s largest developing country, China incurs great costs when a disaster hits. After the Wenchuan earthquake in 2008, the Chinese government focused its attention on the construction of an emergency response system, the creation of disaster prevention and mitigation systems, and the development of a disaster medicine program. Here, we describe the current status of disaster medicine in China, focusing on the following four aspects: the Emergency Management System, Education & Training, Rescue Practices, and Research. We also discuss the future of disaster medicine in China. (Disaster Med Public Health Preparedness. 2018;12:157–165)
Intra-uterine growth restriction (IUGR) impairs postnatal growth and skeletal muscle development in neonatal infants. This study evaluated whether dietary β-hydroxy-β-methylbutyrate Ca (HMB-Ca) supplementation during the early postnatal period could improve muscle growth in IUGR neonates using piglets as a model. A total of twelve pairs of IUGR and normal-birth-weight (NBW) male piglets with average initial weights (1·85 (sem 0·36) and 2·51 (sem 0·39) kg, respectively) were randomly allotted to groups that received milk-based diets (CON) or milk-based diets supplemented with 800 mg/kg HMB-Ca (HMB) during days 7–28 after birth. Blood and longissimus dorsi (LD) samples were collected and analysed for plasma amino acid content, fibre morphology and the expression of genes related to muscle development. The results indicate that, regardless of diet, IUGR piglets had a significantly decreased average daily weight gain (ADG) compared with that of NBW piglets (P<0·05). However, IUGR piglets fed HMB-Ca had a net weight and ADG similar to that of NBW piglets fed the CON diet. Irrespective of body weight (BW), HMB-Ca supplementation markedly increased the type II fibre cross-sectional area and the mRNA expression of mammalian target of rapamycin (mTOR), insulin-like growth factor-1 and myosin heavy-chain isoform IIb in the LD of piglets (P<0·05). Moreover, there was a significant interaction between the effects of BW and HMB on mTOR expression in the LD (P<0·05). In conclusion, HMB-Ca supplementation during the early postnatal period could improve skeletal muscle growth and maturity by accelerating fast-twitch glycolytic fibre development in piglets.
SG-III laser facility is now the largest laser driver for inertial confinement fusion research in China. The whole laser facility can deliver 180 kJ energy and 60 TW power ultraviolet laser onto target, with power balance better than 10%. We review the laser system and introduce the SG-III laser performance here.
A method to design the composite insulation structures in pulsed power systems is proposed in this paper. The theoretical bases for this method include the Weibull statistical distribution and the empirical insulation formula. A uniform formula to describe the reliability (R) for different insulation media such as solid, liquid, gas, vacuum, and vacuum surface is derived. The dependence curves of the normalized applied field on R are also obtained. These curves show that the normalized applied field decreases rapidly as R increases but the declining rates corresponding to different insulation media are different. In addition, if R is required to be higher than a given level, the normalized applied field should be smaller than a certain value. In practical design, the common range of the applied fields for different insulation media should be chosen to meet a global reliability requirement. In the end, the proposed method is demonstrated with a specific coaxial high-voltage vacuum insulator.
To identify the disease-causing gene for a large multi-generational Chinese family affected by familial hypertrophic cardiomyopathy (FHCM), genome-wide screening was carried out in a Chinese family with FHCM using micro-satellite markers, and linkage analysis was performed using the MLINK program. The disease locus was mapped to 1q32 in this family. Screening for a mutation in the cardiac troponin T (cTnT) gene was performed by a PCR and sequencing was done with an ABI Prism 3700 sequencer. A novel C→G transition located in the ninth exon of the cTnT gene, leading to a predicted amino acid residue change from Ile to Met at codon 90, was identified in all individuals with hypertrophic cardiomyopathy (HCM). The results presented here strongly suggest that Ile90Met, a novel mutation in the cTnT gene, is causative agent of HCM in this family.
To evaluate echocardiographically the function and morphology of the right heart subsequent to transcatheter closure of atrial septal defects.
We performed echocardiographic studies in 73 patients undergoing transcatheter closure of atrial septal defects 1 day prior to closure, and then 3 days and 3 months after closure. We calculated the antero-posterior diameter of the right ventricle, the transverse diameter and length of the right atrium, the pulmonary arterial pressure, and the velocities of systolic movement and early and late diastolic movement of the basal parietal walls of the right ventricle.
The atrial septal defects varied in size between 8 and 33 millimetres, and were closed using occluders measuring from 10 to 40 millimetres. At 3 days after closure, the antero-posterior diameter of the right ventricle, the transverse diameter and length of the right atrium, the pulmonary arterial pressure, and the velocities of mural motion were all significantly decreased. After 3 months, the size of the right heart had more or less normalized.
Transcatheter closure of atrial septal defects produces marked improvement in the function and geometry of the chambers of the right heart, reducing pulmonary arterial pressure as well as abolishing the interatrial shunt.
Reports about the role of autoimmunity in amyotrophic lateral sclerosis (ALS) are inconsistent. The aim of this work was to investigate the effect of IgG from patients with ALS on motor neurons in a physiological-like surrounding.
Using affinity chromatography, IgG from six ALS patients, four disease controls and five healthy subjects was purified. Organotypic spinal cord cultures, which conserve the structure of the spinal cord in a horizontal plane and are suitable for studies with long-term treatment, were used and IgG with different concentrations ranging from 0.05 mg/mL to 0.5 mg/mL was added to the culture medium. Ventral motor neuron survival was evaluated by morphology and SMI-32 immunohistochemistry staining. Lactate dehydrogenase (LDH) level in the culture medium was measured by colorimetry.
After cultures were treated with ALS IgG for three weeks, the number and morphology of motor neurons showed little change. In addition, there was no significant difference in lactate dehydrogenase release between cultures treated with medium alone, normal control IgG, disease control IgG or ALS IgG.
The results indicate that IgG from these ALS patients was insufficient per se to induce motor neuron death in Organotypic slice cultures. However, this does not preclude the possibility that other changes may have occurred in the motor neurons. This work offered a new model to evaluate the role of IgG in the pathogenesis of ALS. Organotypic cultures contribute to study of the impact of IgG on motor neurons by mimicking physiological conditions.
Investigation of a program to eradicate amebiasis using consecutive intensive mass screenings followed by medication in a large institute for adults with mental retardation in Taiwan.
Prospective cohort study, with 3 years of follow-up.
A large, 450-bed institution for adults with mental retardation located in southern Taiwan.
All 443 adults with mental retardation in the institution, who have various motor and/or mental handicaps, were included in this study.
A total of 7 consecutive intensive mass screenings for amebiasis for all residents (performed in March, August and November 2001, March and August 2002, January 2003, and May 2004). Infected patients were treated using the standard protocol of the Center for Disease Control of Taiwan.
Enzyme immunoassay testing was used for the amebiasis screening, with the rapid detection of the specific antigen for Entamoeba histolytica in human fecal specimens confirmed by microscopic examination. The serial prevalence and cumulative incidence were then calculated. The prevalence of amebic infection declined in serial screenings, but new infections and reinfections were detected in 5 of 6 follow-up screenings. The prevalence was 10.8% at the beginning of the program and then gradually reduced, falling to 6.3%, 3.6%, 2.7%, 3.4%, and 2.2%. Finally, no more positive cases were identified in the last screening (May 2004). The cumulative incidence rate stabilized at around 40% by the fifth screening. Of the 179 infected patients, 120 had primary infections, with 59 cases of multiple amebic infections.
Active surveillance with intensive mass screening is an effective method of identifying asymptomatic and latent cases of amebiasis in areas where it is endemic, such as an institution for adults with mental retardation.
An amorphous carbon-boron nitride (C-BN) solid was prepared by ball milling the mixture of graphite and hexagonal BN powders for a period of 120 h. After annealing the amorphous C-BN solid for 1 h at atmosphere in the temperature range from 800 to 900 K and then quenching it to room temperature, a small amount of cubic C-BN solid solutions with diamond-like structure, which belong to a high energy phase and can only be synthesized previously under high pressure and temperature (30 GPa, 2000 K), were observed in the annealed amorphous C-BN solid. The lattice constant of the cubic C-BN solid solution was 0.3587 nm, and its grain size was in the range of 10 to 50 nm.
The nanophase ionic conductors Ca1-xLaxF2+x with x=0 and 0.25 were synthesized by an inert gas condensation and in situ compacting technique. The samples with average grain size of 16 na for nanophase CaF2 and 11 nm for nanophase Ca0.75 La0.25F2.25 were prepared under the compacting pressure of 0.5 GPa. The alternating ionic conductivity was deduced from the temperature dependence of the complex impedance.
The results indicated that the logarithm of ionic conductivity obeys Arrhenius relation in the temperature range from 300 °C to 530 °C both for nanophase CaF2 and for nanophase Ca0.75La0.25F2.25. Their activation energies are 1.14 eV and 1.00 eV, respectively. The ionic conductivity of nanophase CaF2 is about one and two orders of magnitude higher than that of polycrystalline and single crystal CaF2, respectively. While the ionic conductivity of nanophase Ca0.75La0.25F2.25 is about one order of magnitude higher than that of nanophase CaF2. Further analysis indicated that the enhanced ionic conductivity of nanophase Ca1-xLaxF2+x is related to the large volume fraction of interfaces.
Ta2O5 films of high reliability and low leakage current density were obtained by low temperature deposition and subsequent high temperature oxygen anneal. At higher temperatures than 410°C, growth was governed by the formation of radicals in gas phase and oxidation on the surface, while at lower temperatures by the dissociation of reactant on the surface of substrates. As a result, the films deposited at lower temperatures had undensified structures, and contained more carbon that might be a leakage current source in Ta2O5 film. During post-deposition heat treatment in 800°C oxidating ambient, carbon was removed away and silicon was diffused from the substrate into the Ta2O5 film efficiently for its as-grown porous structure. After oxygen anneal, low temperature films get denser and are crystallized to mixed phase of orthorhombic and hexagonal Ta2O5, while high temperature films crystallized to orthorhombic single phase. Ta2O5 capacitor with low temperature films showed superior leakage characteristics applicable to sub-half micron memory devices.
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