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  • Author: Ling He x
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Human IgG inhibits IgA1 protease-dependent adherence of Haemophilus influenza strains to human lung epithelial cells

Abstract

Background: IgA1 protease may enhance the bacterial infection in human beings. However, the molecular mechanism of bacterial adherence to eukaryotic cells is unclear.

Objective: Reveal the mechanisms of IgA1 protease-dependent and non-protease bacterial adherence to eukaryotic cells.

Method: Type I and type II IgA1 proteases from iga genes (GenBank DQ683355 for NTHi465, DQ683356 for NTHi500 and DQ683357 for Nm430) were cloned, expressed, and purified. Cellular assays for adherence of IgA1 protease-producing and -non-producing and typable and nontypable strains of H. influenzae to human lung carcinoma cells (A549) were carried out in the presence of human antibodies.

Results: Adherence of protease-producing strains and non-producing strains to human epithelial cells was significantly dependent on the enzyme activity. In addition, human IgG was an inhibitor to IgA1 proteasedependent adherence of H. influenzae strains to human cells. However, IgA1 antibodies were irrelevant to IgA1 protease-dependent adherence.

Conclusion: IgA1 protease was required for adherence of pathogenic bacteria to human epithelial cells in IgA1 protease-producing bacteria, and human IgG inhibits the adherence, but not for IgA1 protease non-producing bacteria.

Open access
Self-esteem enhancement as a strategy for promoting the mental health and averting the occupational problems of nurses

Abstract

In recent years, shortage of nurses, high turnover rate, low self-worth, and team instability have become increasingly serious. With the development of positive psychology, more and more nursing managers have begun to attach great importance to the mental health of nurses. Self-esteem, as one of the core indicators of individual mental health, has received extensive attention from researchers in different fields since its inception. This paper reviews and summarizes the research status and development trends of nurses’ self-esteem considering the aspects of self-esteem as a concept, assessment tools, significance, and intervention methods. At the same time, it also puts forward problems that need to be solved by undertaking research into nurses’ self-esteem, in order to provide a reference for further studies on nurses’ self-esteem.

Open access
Analysis and Simulation on the Effect of Rotor Interturn Short Circuit on Magnetic Flux Density of Turbo–Generator

Abstract

The intent of this paper is to investigate the effect of the interturn short circuit fault (ISCF) in rotor on the magnetic flux density (MFD) of turbo-generator. Different from other studies, this work not only pays attention to the influence of the faulty degrees on the general magnetic field, but also investigates the effect of the short circuit positions on the harmonic components of MFD. The theoretical analysis and the digital simulation through the FEM software Ansoft are performed for a QSFN-600-2YHG turbo-generator. Several significant formulas and conclusions drawn from the analysis and the simulation results are obtained to indicate the relation between the harmonic amplitude of the MFD and the faulty degree (via nm, the number of the short circuit turns), and the relation between the MFD harmonic amplitude and the faulty position (via αr, the angle of the two slots in which the interturn short circuit occurs). Also, the developing tendency of the general magnetic field intensity, the distribution of the magnetic flux lines, and the peak-to-peak value of MFD are presented.

Open access
An Experimental Study on the Mechanisms of Ge Hua Jie Cheng Decoction for Rats with Alcoholic Liver Injuries

Abstract

Objective: To explore the effects and underlying mechanisms of Ge Hua Jie Cheng Decoction on rats with alcoholic liver injuries.

Methods: 60 Wistar rats were randomly assigned to six groups: normal group, model group, Yi Gan Ling group, and Ge Hua Jie Cheng Decoction groups in low, middle and high concentrations, 10 rats in each group. Except for the normal group, rats in other groups were administered white wine for eight weeks to establish the liver injury model. During the modeling, the Yi Gan Ling/Ge Hua Jie Cheng Decoction were administered intragastrically to the rats. So the histopathological changes were observed after eight weeks, meanwhile the serum γ- glutamyl endopeptidase (GGT), Glutathione (GSH) and aspartate aminotransferase mitochondrial isoenzyme (m-AST) were assayed by automatic biochemical analyzer.

Results: under the light microscope, the groups of high and middle dosages of Ge Hua Jie Cheng Decoction , especially the high one, had apparent improvement of inflammatory infiltration in liver tissues. Compared with the normal group, the serum GGT and m-AST levels had elevated (P<0.01), whereas the serum GSH level decreased (P<0.01); compared with model group, the high and middle dosages of Ge Hua Jie Cheng Decoction groups had decreased serum GGT and m-AST (P<0.01 or P<0.05), as well as increased serum GSH level (P<0.01).

Conclusion: Ge Hua Jie Cheng Decoction has a protective effect for liver injuries induced by alcohol, and this effect is dose-dependent. The high dosage showed stronger protection effect, which might be related to the increased serum GSH and decreased serum GGT and m-AST.

Open access
Fault Risk Assessment of Underwater Vehicle Steering System Based on Virtual Prototyping and Monte Carlo Simulation

Abstract

Assessing the risks of steering system faults in underwater vehicles is a human-machine-environment (HME) systematic safety field that studies faults in the steering system itself, the driver’s human reliability (HR) and various environmental conditions. This paper proposed a fault risk assessment method for an underwater vehicle steering system based on virtual prototyping and Monte Carlo simulation. A virtual steering system prototype was established and validated to rectify a lack of historic fault data. Fault injection and simulation were conducted to acquire fault simulation data. A Monte Carlo simulation was adopted that integrated randomness due to the human operator and environment. Randomness and uncertainty of the human, machine and environment were integrated in the method to obtain a probabilistic risk indicator. To verify the proposed method, a case of stuck rudder fault (SRF) risk assessment was studied. This method may provide a novel solution for fault risk assessment of a vehicle or other general HME system.

Open access
Moisture Comfort and Antibacterial Properties of Elastic Warp-Knitted Fabrics

Abstract

Multifunction elastic warp-knitted fabrics were fabricated on a crochet machine with the use of metal composite yarns/viscose yarn and bamboo polyester/ crisscross-section polyester hybrid yarns as the front face and back face of the knitted fabric structure, respectively. We investigated the effect of the blend ratio of bamboo charcoal/ crisscross-section polyester multiply yarns on the fabric's moisture comfort properties, such as water vapour transmission (WVT), water evaporation rate (WER), and water absorbency. The results showed that blending ratio significantly influenced WVT and WER. Moreover, antibacterial activity of the elastic warp- knitted fabric was tested against Staphylococcus aureus and Escherichia coli in accordance with AATCC 90-2011. Finally, the extension- stress value curves were used to analyse the elastic stretching property, and the fabric exhibited greater breaking elongation and lower stress value in the walewise than in the weft direction.

Open access
Effects of Al doping on defect behaviors of ZnO thin film as a photocatalyst

Abstract

Al doped ZnO (AZO) thin films were prepared on silica substrates by sol-gel method. The films showed a hexagonal wurtzite structure with a preferred orientation along c-axis. Suitable Al doping dramatically improved the crystal quality compared to the undoped ZnO films. Dependent on the Al dopant concentration, the diffraction peak of (0 0 2) plane in XRD spectra showed at first right-shifting and then left-shifting, which was attributed to the change in defect concentration induced by the Al dopant. Photocatalytic properties of the AZO film were characterized by degradation of methyl orange (MO) under simulated solar light. The transmittance of the films was enhanced by the Al doping, and the maximum transmittance of 80 % in the visible region was observed in the sample with Al concentration of 1.5 at.% (mole fraction). The film with 1.5 at.% Al doping achieved also maximum photocatalytic activity of 68.6 % under solar light. The changes in the film parameters can be attributed to the variation in defect concentration induced by different Al doping content.

Open access
An Outbreak of SARS in a Diabetes Room of a General Hospital without Infected Medical Staff

Abstract

Objective To investigate the epidemiologic features of an outbreak of SARS that occurred in a single diabetes room of a general hospital in Beijing in late March 2003.

Methods Field investigation was carried out in the ward, the nursing log and the hospitalization medical record of correlative patients were consulted. SARS-CoV in serum specimen from SARS patient was detected by PCR.

Results The room where SARS outbreak occurred was on the 13th floor of the 16-story main ward building. There were 6 beds in the room, living with 6 female patients (aged 45-67) who were all hospitalized due to type 2 diabetes. On March 24, 2003, Patient 1 began to have a fever and cough, chest X-ray showed pneumonia. Five and six days later, Patient 2 and Patient 3 began to have a fever, respectively. Finally, all of these 3 patients died. Their beds were all at the same side of the room, and the other 3 patients at the opposite side were not infected. Serum SARS CoV-RNA of the Patient 3 was positive by nest-PCR. The daughter-in-law of Patient 1 who accompanied Patient 1 by the bedside several days, mainly near the window, upwind of Patient 1, was not infected. Medical staff, family members and visitors of the 6 patients were not infected.

Conclusions This outbreak was not transmitted by aerosol. The distance droplets travels could be up to 3.43 meters. Droplet spread has direction, and the droplets direction of propagation is closely related with the wind direction and speed. Those at the downwind position of SARS patients were susceptible to be infected. Medical staff wore face masks and good natural ventilation of this ward building may be important reasons for the prevention of infection.

Open access