Research on Dynamic Strength and Inertia Effect of Concrete Materials Based on Large-Diameter Split Hopkinson Pressure Bar Test

The Split Hopkinson Pressure Bar (SHPB) test device is an important tool to study the dynamic characteristics of concrete materials. Inertial effect is one of the main factors that cause inaccurate results in SHPB tests of concrete materials. To solve this problem, Large-diameter SHPB tests on concrete and mortar were performed. A dynamic increase factor (DIF) model considering strain rate effect and inertia effect was established. This model provides a scientific reference for studying the dynamic mechanical properties of concrete materials. The experimental results indicate that the strain rate effect of concrete is more sensitive than that of mortar, but the inertia effect of mortar is more sensitive than that of concrete. Under the same strain rate, the energy utilization rate, average fragment size, and impact potentiality of mortar are higher than concrete.     

Electrochemical Evaluation of Stress Corrosion Cracking Susceptibility of Ti-6Al-3Nb-2Zr-1Mo Alloy Welded Joint in Simulated Deep-Sea Environment

Titanium alloys have high specific strength and excellent corrosion resistance and have been applied in deep-sea engineering fields. However, stress corrosion cracking may become one of the biggest threats to the service safety of a high-strength titanium alloy, as well as its weldment. In this work, stress corrosion cracking of a gas-tungsten-arc-welded Ti-6Al-3Nb-2Zr-1Mo (Ti6321) alloy influenced by the applied potentials in simulated deep-sea and shallow-sea environments was investigated by combining slow strain rate testing with electrochemical measurements. The results showed that the service environment and applied potential have a substantial effect on the stress corrosion cracking behavior of the Ti6321 welded joint. The Ti6321 welded joint exhibited higher stress corrosion susceptibility in a simulated deep-sea environment and at a strong polarization level owing to the diminishing protection of the passive film under passivation inhibition and the enhancement of the hydrogen effect. The fracture of a Ti6321 welded joint in the weld material could be attributed to the softening effect of the thick secondary α within the coarse-grained martensite. The electrochemical evaluation model of stress corrosion cracking susceptibility of a Ti6321 welded joint in a simulated marine environment was established by adding the criterion in the passivation region based on the literature model, and four potential regions corresponding to different stress corrosion cracking mechanisms were classified and discussed. Our study provides useful guidance for the deep-sea engineering applications of Ti6321 alloys and a rapid assessment method of stress corrosion risk.     

A High-Fat Diet Induces Muscle Mitochondrial Dysfunction and Impairs Swimming Capacity in Zebrafish: A New Model of Sarcopenic Obesity

Obesity is a highly prevalent disease that can induce metabolic syndrome and is associated with a greater risk of muscular atrophy. Mitochondria play central roles in regulating the physiological metabolism of skeletal muscle; however, whether a decreased mitochondrial function is associated with impaired muscle function is unclear. In this study, we evaluated the effects of a high-fat diet on muscle mitochondrial function in a zebrafish model of sarcopenic obesity (SOB). In SOB zebrafish, a significant decrease in exercise capacity and skeletal muscle fiber cross-sectional area was detected, accompanied by high expression of the atrophy-related markers Atrogin-1 and muscle RING-finger protein-1. Zebrafish with SOB exhibited inhibition of mitochondrial biogenesis and fatty acid oxidation as well as disruption of mitochondrial fusion and fission in atrophic muscle. Thus, our findings showed that muscle atrophy was associated with SOB-induced mitochondrial dysfunction. Overall, these results showed that the SOB zebrafish model established in this study may provide new insights into the development of therapeutic strategies to manage mitochondria-related muscular atrophy.     

Increasing on-treatment hepatocellular carcinoma risk with decreasing baseline viral load in HBeAg-positive chronic hepatitis B

BACKGROUNDIt is unclear whether the level of serum hepatitis B virus (HBV) DNA at baseline affects the on-treatment risk of hepatocellular carcinoma (HCC) in hepatitis B e antigen–positive (HBeAg-positive), noncirrhotic patients with chronic hepatitis B (CHB).METHODSWe conducted a multicenter cohort study including 2073 entecavir- or tenofovir-treated, HBeAg-positive, noncirrhotic adult CHB patients with baseline HBV DNA levels of 5.00 log₁₀ IU/mL or higher at 3 centers in South Korea between January 2007 and December 2016. We evaluated the on-treatment incidence rate of HCC according to baseline HBV DNA levels.RESULTSDuring a median 5.7 years of continuous antiviral treatment, 47 patients developed HCC (0.39 per 100 person-years). By Kaplan-Meier analysis, the risk of HCC was lowest in patients with baseline HBV DNA levels of 8.00 log₁₀ IU/mL or higher, increased incrementally with decreasing viral load, and was highest in those with HBV DNA levels of 5.00–5.99 log₁₀ IU/mL (P < 0.001). By multivariable analysis, the baseline HBV DNA level was an independent factor that was inversely associated with HCC risk. Compared with HBV DNA levels of 8.00 log₁₀ IU/mL or higher, the adjusted HRs for HCC risk with HBV DNA levels of 7.00–7.99 log₁₀ IU/mL, 6.00–6.99 log₁₀ IU/mL, or 5.00–5.99 log₁₀ IU/mL were 2.48 (P = 0.03), 3.69 (P = 0.002), and 6.10 (P < 0.001), respectively.CONCLUSIONOn-treatment HCC risk increased incrementally with decreasing baseline HBV DNA levels in the range of 5.00 log₁₀ IU/mL or higher in HBeAg-positive, noncirrhotic adult patients with CHB. Early initiation of antiviral treatment when the viral load is high (≥8.00 log₁₀ IU/mL) may maintain the lowest risk of HCC for those patients.FUNDINGPatient-Centered Clinical Research Coordinating Center (PACEN) (grant no. HC20C0062) of the National Evidence-based Healthcare Collaborating Agency; National R&D Program for Cancer Control through the National Cancer Center (grant no. HA21C0110), Ministry of Health and Welfare, South Korea.     

Increased expression of receptor activator of nuclear factor-κB ligand in osteoblasts from adolescent idiopathic scoliosis patients with low bone mineral density

Persistent generalized low bone mineral density (BMD) has been reported in patients with adolescent idiopathic scoliosis (AIS).However,the exact mechanisms and causes of the low BMD in AIS patients are largely unknown.The purpose of this study was to examine the relationship between the receptor activator of NF-κB ligand (RANKL)/osteoprotegerin (OPG) levels in osteoblasts (OBs) from AIS patients with low BMD and with comparison made between the patients and controls.Twenty AIS patients and eight age-matched controls were included in the present study.The BMD of lumbar spine and proximal femur was measured in all subjects.OBs from the cancellous bone of each subject was harvested and primarily cultured.The mRNA and protein expression of RANKL and OPG in OBs was detected by RT-PCR and Western blotting.The results showed BMD was lower in AIS patients than in controls.A significantly higher mRNA and protein expression of RANKL was observed in OBs from AIS patients,while no significant difference was found in the expression of OPG between AIS patients and controls.As a result,RANKL/OPG ratio in patients with AIS was remarkably higher than controls.Our study preliminarily demonstrated expression of RANKL was higher in OBs from AIS patients with low BMD as compared with controls,suggesting the unbalanced RANKL/OPG ratio caused by an over-expression of RANKL in OBs may be responsible for the low BMD in AIS patients.     

S—180肿瘤核糖核酸体外对小鼠脾淋巴细胞蛋白质合成的影响

用~H-Lcu参入的方法,观察到小鼠腹水型Tu—RNA能显著地抑制小鼠脾淋巴细胞的蛋白质合成。这种抑制效应无RNA来源的肿瘤特异性,但具有组织特异性。主要活性成分可能存在于RNasc酶解混合物的Scphadex G—100层析第二组分中。     

银屑病分型论治浅解

银屑病又名牛皮癣,中医称之为白疕,是一种常见易复发的慢性炎症性皮肤病,以云母状鳞屑、红膜症、点状出血为临床特征.近年来,银屑病发病呈上升趋势,其初期有明显的季节性,呈冬重夏轻,无论男女老幼皆可发病,目前病因未明,尚缺乏有效的治疗方法.自2000年以来,我们根据银屑病的临床表现,将其辨证分型为:血热毒盛,寒湿侵袭、脉络瘀阻、血虚风燥、肝肾亏虚等五型,对证治疗取得了比较明显的疗效,现予介绍,以求同道斧正.     

环氧氯丙烷升高血糖作用的动力学特性和肾上腺超微结构改变

环氧氯丙烷具有升高血糖作用。血糖升高有良好的剂量效应关系和时间效应关系。血糖达峰值后恢复10%,50%,90%的效应与持续时间曲线斜率随剂量增加而递减,提示环氧氯丙烷在体内消除和转运具有多房室模型特性,血糖达峰值持续时间较长。说明环氯氧丙烷升高血糖作用部位在周边室。环氧氯丙烷引起肾上腺皮质束状带细胞光面内质网增多和脂滴增加,髓质肾上腺素细胞分泌颗粒增多和高尔基复合体发达。说明环氧氯丙烷作用于肾上腺皮质束状带细胞,引起糖皮质激素增加,诱导髓质肾上腺素细胞内PNMT增加和活性增强,促使肾上腺素增多,导致血糖升高。