The contact force between lunar-based equipment and lunar soil.

Lunar-based equipment plays a vital role in the exploration of the moon because it undertakes the tasks of moving, transporting, digging, and so on. In order to control the gait of lunar-based equipment more precisely and guarantee mobile stability, the contact mechanism between its foot and lunar soil is worthy of in-depth study. In this paper, a contact model is proposed to predict the stress, strain, and displacement both on the contact surface and in the lunar soil when the foot is under vertical load. The axial stress in the proposed contact model is verified through the experiment and its accuracy in the lunar equipment is verified through simulation. The error is in a reasonable range and the influence depth of load conforms to the experiment results. This paper provides a relatively accurate model to describe the contact force between the lunar-based equipment's foot and the lunar soil and will promote the research of lunar exploration.

[Helicobacter pylori infection in the gastric mucosa of patients with HIV/AIDS in different clinical stages].

OBJECTIVE: To analyze Helicobacter pylori infection in the gastric mucosa of patients with HIV/AIDS in different clinical stages. METHODS: This study involved 170 patients with HIV/AIDS and 34 HIV-negative patients. All the patients underwent upper endoscopy and antral gastric biopsy to determine the status of Helicobacter pylori infection using aniline red staining and rapid urease test. The patients with HIV/AIDS were stratified based on CD4(+)T lymphocyte counts and clinical setting into asymptomatic HIV infection (A1, A2) group, symptomatic HIV infection (B1, B2) group and AIDS (A3, B3, C1-3) group. RESULTS: The prevalence of Helicobacter pylori infection in HIV/AIDS patients was 16.5% (28/170), and in the 3 groups classified, the infection rates were 23.4% (11/47), 14.0% (8/57), and 13.6% (9/66), respectively; the infection rate was 47.1% (16/34) in the control group. Helicobacter pylori infection rate in the gastric mucosa of the patients with HIV/AIDS in different clinical stages was significantly lower than that of the control group (P<0.05); the infection rates in symptomatic HIV-infected (B1, B2) group and AIDS (A3, B3, C1-3) group were significantly lower than that in asymptomatic HIV-infected (A1, A2) group (P<0.05). CONCLUSION: The low Helicobacter pylori infection rate in HIV/AIDS patients may result from severe immunodeficiency in the gastric mucosa.

Tumor necrosis factor--alpha gene promoter polymorphisms in Chinese patients with nonalcoholic fatty liver diseases.

BACKGROUND: Nonalcoholic Fatty Liver Disease (NAFLD) encompasses a histopathological spectrum of clinical conditions such as simple fatty liver (steatosis), nonalcoholic steatohepatitis (NASH), and a variant that has degrees of fibrosis. Tumor Necrosis Factor-alpha (TNF-alphalpha) is considered essential for NAFLD. Therefore, we investigated the correlation between TNF-alphalpha gene promoter polymorphism and NAFLD in this human study. PATIENTS AND METHODS: The TNF-alpha gene polymorphisms at position -238 and -308 were analyzed in 189 Chinese patients with NAFLD and 138 healthy controls by using polymerase chain reaction and restriction fragment length polymorphism assay. The serum levels of TNF-alpha in both patient and control groups were measured by ELISA. The associations of TNF-alpha polymorphism and serum TNF-alpha, and/or insulin resistance, and/or clinical features were analyzed. RESULTS: The carrier frequencies of TNF-alpha gene polymorphism with G/A mutation at -238 were significantly higher in the patients with NAFLD than those in the control subjects (p < 0.05). However, there were no significant differences between the NAFLD patients and control subjects in the polymorphisms at -308 (p > 0.05). In addition, the serum level of TNF-alpha was markedly higher in the patients with NAFLD than in the control subjects (p < 0.05). There were significant associations between TNF-alpha gene polymorphism in the -238 A allele and increased serum TNF-alpha, insulin resistance, as well as increased body mass index in the NAFLD patients. CONCLUSIONS: The results indicate that the TNF-alpha gene polymorphism at position -238 is associated with susceptibility of nonalcoholic Fatty Liver Disease in a Chinese population.

[Association of serum leptin and insulin resistance with nonalcoholic fatty liver disease].

OBJECTIVE: To investigate the relationship among serum leptin, homeostasis model assessment of insulin resistance (HOMA-IR), body mass index (BMI) and dyslipidema in patients with nonalcoholic fatty liver disease (NAFLD). METHODS: Eighty-two patients with NAFLD were divided into mild, moderate and severe NAFLD groups according histological examination results of the liver. Twenty healthy volunteers were chosen as the normal control (NC) group. Fasting insulin, glucose, leptin and lipid levels were measured in the 82 patients with NAFLD and the BMI calculated. IR index of the patients was calculated according to the HOMA method. RESULTS: Leptin, HOMA-IR index, BMI and dyslipidemia showed significant differences between NAFLD and NC groups (P<0.05 or 0.01). Leptin and HOMA-IR index increased with the exacerbation of NAFLD, both of which were positively correlated with the severity of NAFLD. CONCLUSION: Increased leptin level, HOMA-IR, BMI and dyslipidemia can be important risk factors of NAFLD, and serum leptin level and HOMA-IR are positively correlated with the severity of NAFLD.