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As one of the protective components, the high strength low alloy structural steel plate had attracted extensive attention because of frequent threats of explosive loads. In this paper, combining explosion experiment, finite element model (FEM) and multi-scale microscopic observation technique, the relationship between macroscopic dynamic response and microscopic damage of low alloy steel plate under the close-range explosion (i.e., 2 cm, 3 cm, 6 cm, and 10 cm) was investigated. After the explosion experiments and validation of the FEMs of the four steel plates, the thickness sections of the position closest to the explosives were selected for microscopic observation of different scales. According to the observation results, the defects were characterized and mainly divided into four damage types. Subsequently, based on the numerical simulation data and microscopic observation results, three models were established to describe the change rules of impulse-explosive distance (I-E), texture-explosive distance (T-E), as well as impulse-texture (I-T), respectively. The results showed that when the explosive distance was 2–10 cm, I-E and T-E were consistent with the quadratic fit. In addition, the texture of base material (BM) was 3.42, which was 2.36 times larger than that of closest explosive distance sample. The variation law of I-T better revealed the relationship between the macroscopic dynamic response and microscopic damage with different explosive distances which agreed with the linear model. These results can be used to predict and prevent damage propagation of low alloy steel plate under the close-range explosion and improve the protective ability of protective materials. [ABSTRACT FROM AUTHOR]

Human immunodeficiency virus (HIV) infection is a risk factor of cardiovascular diseases (CVDs). HIV-infected patients exhibit cardiac dysfunction coupled with cardiac fibrosis. However, the reason why HIV could induce cardiac fibrosis remains largely unexplored. HIV-1 trans-activator of transcription (Tat) protein is a regulatory protein, which plays a critical role in the pathogenesis of various HIV-related complications. In the present study, recombinant Tat was administered to mouse myocardium or neonatal mouse cardiac fibroblasts in different doses. Hematoxylin–eosin and Masson's trichrome staining were performed to observe the histological changes of mice myocardial tissues. EdU staining and MTS assay were used to evaluate the proliferation and viability of neonatal mouse cardiac fibroblasts, respectively. Real-time PCR and western blot analysis were used to detect CTGF, TGF-β1, and collagen I mRNA and protein expression levels, respectively. The results showed that Tat promoted the occurrence of myocardial fibrosis in mice. Also, we found that Tat increased the proliferative ability and the viability of neonatal mouse cardiac fibroblasts. The protein and mRNA expression levels of TGF-β1 and CTGF were significantly upregulated both in Tat-treated mouse myocardium and neonatal mouse cardiac fibroblasts. However, co-administration of TGF-β inhibitor abrogated the enhanced expression of collagen I induced by Tat in neonatal mouse cardiac fibroblasts. In conclusion, Tat contributes to HIV-related cardiac fibrosis through enhanced TGF-β1-CTGF signaling cascade. [ABSTRACT FROM AUTHOR]

To explore the relationship between the geographical factors and P-R interval reference value of healthy adults, and to elucidate the geographical distribution of the P-R interval reference value in Chinese adults, to provide the basis for the standard of P-R interval reference value in different regions. The P-R interval reference value of 64,753 healthy adults in 341 cities (counties) level hospitals, research institutes, and universities in China was collected, and 15 geographical data and P-R interval reference value of healthy people were studied, and then 10 geographical factors with correlation were extracted for further analysis. Using spatial autocorrelation analysis to determine the autocorrelation of data space, using backward regression and ridge regression to construct forecast model, and the optimal prediction model is selected by comparing and evaluating the prediction effect of each model, the spatial distribution map of P-R interval reference value of Chinese healthy adults was constructed by statistical analysis. There was a significant correlation between normal reference value of adult P-R interval reference value and geographical factors. The regression model of normal reference value and geographical factors of adult P-R interval reference value was established by ridge regression analysis method: Y ̂ =149.2 + 0.02590X2 + 0.0005000X3 + 0.02634X5–0.05890X6 + 0.0008400X7 + 0.01606X8 + 0.2592X9–0.03638X12 + 5.888X13–0.2126X15 ± 8.6, and ArcGIS10.2. In the software interpolation method, the distribution chart of normal reference value of Chinese adult P-R interval reference value was inserted. Knowing the geographical factors of some places in China, we can use this model to estimate the P-R interval reference value in this region, and to obtain the normal P-R interval reference value between adults anywhere in China. [ABSTRACT FROM AUTHOR]

In this paper, experiments and theoretical analysis were conducted to elucidate the internal relation between base metal misorientation and the characteristics of DD5 single-crystal superalloy TLP joints. The alloy was bonded at 1513 K for 10 h in vacuum environment. High-temperature creep rupture tests were carried out to determine the joint’s quality. Results revealed that base metal misorientation exerted a remarkable influence on DD5 alloy TLP joints. The joints of base metals with [001] orientation were used in this research. When the misorientation was smaller than 9°-10°, the single crystallization of joints can be realized and joints can achieve excellent mechanical properties. When the misorientation was more than 10°, there would be second-phase particles distributed in grain boundaries, thus resulting in poor mechanical property of joint; moreover, the characteristics of joint did not change with base metal misorientation in this case. [ABSTRACT FROM AUTHOR]

Potassium (K) plays an important role in the regulation of plant growth and development. However, how potassium works in K channels in strawberry fruit development is yet unknown. Here, a 2205 bp potassium channel cDNA encoding 734 amino acids, named FaKAT1, was cloned from strawberry fruits. Bioinformatics analysis showed that the cis-element ABRE responsive to ABA and conserved domains characteristic to the KAT1 superfamily were found in the promoter and encoding protein of FaKAT1. Transcription analysis revealed that FaKAT1 was expressed higher in stems and leaves, followed by fruits, but was less in roots and flowers, and that coupled with the fruit red-coloring, its transcripts increased rapidly, suggesting that FaKAT1 might play a role in ripening. Using tobacco rattle virus-induced gene silencing, downregulation of the FaKAT1 transcripts resulted in significant unripening of fruits, which is consistent with changes of the ripening-related events and genes, such as fruit firmness, contents of titratable acid, sugar, anthocyanin, and abscisic acid (ABA), as well as transcripts of PYR1, ABI1, SnRK2, GAL6, PE5, EXP2, XYL2, CA4H, CHS, CHI, DFR, and 4CL. Furthermore, ABA and the ABA inhibitor, fluridone, promoted and inhibited the mRNA expression levels of FaKAT1, respectively. Importantly, a K channel blocker, tetraethylammonium, also inhibited FaKAT1 expression and fruit red coloring. In conclusion, FaKAT1 is an ABA-induced K channel, which regulates strawberry fruit ripening. [ABSTRACT FROM AUTHOR]

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The physical process of forming a modified region in soda-lime glass was investigated using 1 kHz intense femtosecond laser pulses from a Ti: sapphire laser at 775 nm. Through the modifications induced by the femtosecond laser radiation using selective chemical etching techniques, we fabricated reproducible and defined microstructures and further studied their morphologies and etching properties. Moreover, a possible physical mechanism for the femtosecond laser modification in soda-lime glass was proposed. [ABSTRACT FROM AUTHOR]

Experimental investigations have been done to verify the effects of hold time during transient liquid-phase bonding on joint microstructure and mechanical properties of a nickel-based single crystal superalloy. The superalloy was bonded at 1473-1513 K for 0.25-12 h in vacuum environment. A set of parameters, 1513 K for 10 h, was determined as the optimum bonding condition. SEM results revealed that the joint without the completion of isothermal solidification is comprised of four different distinct regions, namely, rapid solidification zone (RSZ), isothermal solidification zone (ISZ), diffusion zone, and base metal. EBSD data indicated that the ISZ across the centerline of the bond has an undifferentiated crystallographic orientation being the same as the base metal. At increasing hold times at 1513 K, RSZ and also borides would disappear and result in an improvement of mechanical properties. Mechanical property tests at elevated temperatures have been done to determine the joints' quality. High-temperature creep rupture strength (for 100 h at 1373 K) and tensile strength (at 1273 K) of the joints could both attain 90% of those of the base metal. [ABSTRACT FROM AUTHOR]

With linearly coupled nonlinear Schrodinger equations, numerical analysis has been performed on the mode locking forming procedure of a fiber laser in the linear cavity configuration. The fiber is Yb-doped multi-core photonic crystal fiber and semiconductor saturable absorber mirror (SESAM) is adopted as the nonlinear transmission element to start mode locking. Because of the noise randomness, initial pulse would be picked out by SESAM in one or more cores which makes the multi-core mode locking quite different from single-core one. The two situations are compared and fully discussed. Mode locking in multi-core photonic crystal fiber laser can be realized only if the couple coefficient between the cores and the temporal overlap between the pulses in different cores are large enough. [ABSTRACT FROM AUTHOR]

The influence of the pump pulse, group-velocity mismatch, dispersion and self-phase modulation & cross phase modulation on the phase transfer in the OPA process were analyzed. The results show that very sharp phase modulation can be maintained in mid infrared range by optical parametric amplifier. The period and depth of the periodic modulation can also be maintained due to small group-velocity mismatching in the calculated wavelength range. [ABSTRACT FROM AUTHOR]

A high pulse energy femtosecond fiber laser based on a large-mode-area photonic crystal fiber is demonstrated. A segment of Yb-doped single-polarization large-mode-area photonic crystal fiber with extremely low nonlinearity is explored as gain media of this fiber laser, resulting in intrinsically environmentally stability. The fiber laser is based on a linear cavity with dispersion compensation free configuration, and the stable mode-locking is obtained by a semiconductor saturable absorber mirror (SESAM). The fiber laser directly generates 2.5 W of average power at a repetition rate of 51.4 MHz, corresponding to a single pulse energy of 50 nJ. The output pulse duration is 4.2 ps, which is dechirped to 410 fs after extracavity dispersion compensation. The nonlinear absorption of SESAM determines the pulse shaping at low output power, while the mode-locking mechanism is under the balance between spectrum broadening from self-phase-modulation and gain filtering at the high output power. [ABSTRACT FROM AUTHOR]

Amplified spontaneous emission (ASE) and its restraint in a femtosecond Ti: sapphire chirped-pulse amplifier were investigated. The noises arising from ASE were effectively filtered out in the spatial, temporal and spectral domain. Pulses as short as 38 fs were amplified to peak power of 1.4 MI. The power ratio between the amplified femtosecond pulse and the ASE was higher than 106: 1. [ABSTRACT FROM AUTHOR]

The characteristics of supercontinuum produced by high-intensity femtosecond pulses were investigated under different interaction lengths, various pump intensities, different pump wavelengths at the fundamental 800 nm and its second-harmonic 400 nm. High transfer-efficiency supercontinuum with flat-top in liquid media was produced. As the main nonlinear mechanisms, the effects of self-phase modulation (SPM) and four-photon parametric emission were also investigated. [ABSTRACT FROM AUTHOR]