Association between short-term exposure to ambient air pollutants and the risk of hospital visits for acute upper respiratory tract infections among adults: a time-series study in Ningbo, China.

OBJECTIVES: Acute upper respiratory tract infections (AURTIs) are prevalent in the general population. However, studies on the association of short-term exposure to air pollution with the risk of hospital visits for AURTIs in adults are limited. This study aimed to explore the short-term exposure to air pollutants among Chinese adults living in Ningbo. METHODS: Quasi-Poisson time serious regressions with distributed lag non-linear models (DLNM) were applied to explore the association between ambient air pollution and AURTIs cases. Patients ≥ 18 years who visit three hospitals, being representative for urban, urban-rural junction and rural were included in this retrospective study. RESULTS: In total, 104,441 cases with AURTIs were enrolled in hospital during 2015-2019. The main results showed that particulate matter with an aerodynamic diameter less than 2.5 µm (PM2.5), nitrogen dioxide (NO2) and nitrogen dioxide (SO2), were positively associated to hospital visits for AURTIs, except for nitrogen dioxide (O3), which was not statistically significant. The largest single-lag effect for PM2.5 at lag 8 days (RR = 1.02, 95%CI: 1.08-1.40), for NO2 at lag 13 days (RR = 1.03, 95%CI: 1.00-1.06) and for SO2 at lag 5 days (RR = 1.27, 95%CI: 1.08-1.48), respectively. In the stratified analysis, females, and young adults (18-60 years) were more vulnerable to PM2.5 and SO2 and the effect was greater in rural areas and urban-rural junction. CONCLUSIONS: Exposure to ambient air pollution was significantly associated with hospital visits for AURTIs. This study provides epidemiological evidence for policymakers to control better air quality and establish an enhanced system of air pollution alerts.

Natural flavonols as probes for direct determination of borax: From conventional fluorescence analysis to paper-based smartphone sensing.

Borax is strictly regulated in the food processing and pharmaceutical industry due to its physiological toxicity, and the development of a direct analytical method is essential for effectively monitoring the borax abuse. In this work, the fluorescence properties of flavonoids, including flavones, isoflavones and flavonols, were systematically investigated from aqueous to borax solutions, and it was found that the weak intrinsic fluorescence of flavonols could be pervasively sensitized by borax. A natural flavonol, morin, was subsequently chosen as a representative probe to develop a turn-on fluorescence sensing method for borax analysis, which achieved a linear response spanning four orders of magnitude with a detection limit of 1.07 µM (0.22 µg mL-1 in terms of Na2B4O7 content). Furthermore, a smartphone-assisted paper-based test device was designed and constructed by 3D printing technology. Using morin-impregnated test strips as the carrier, the borax could be visually detected by the RGB signals of the captured images, with a detection limit of 0.13 mM (27.05 µg mL-1 for Na2B4O7). Combining ion exchange treatment for food samples and sodium periodate oxidation for drug samples, the developed methods were successfully applied for the direct analysis of borax in various products with the recoveries of 86.9-106.3% for traditional fluorescence analysis and 82.7-108.8% for smartphone-assisted fluorescence sensing. The fluorescence property of the morin-borax system was studied using time-dependent density functional theory, and the sensing mechanism was discussed in conjunction with experimental research.

Effectiveness of a WHO self-help psychological intervention to alleviate stress among healthcare workers in the context of COVID-19 in China: a randomised controlled trial.

AIMS: To examine the effectiveness of Self-Help Plus (SH+) as an intervention for alleviating stress levels and mental health problems among healthcare workers. METHODS: This was a prospective, two-arm, unblinded, parallel-designed randomised controlled trial. Participants were recruited at all levels of medical facilities within all municipal districts of Guangzhou. Eligible participants were adult healthcare workers experiencing psychological stress (10-item Perceived Stress Scale scores of ≥15) but without serious mental health problems or active suicidal ideation. A self-help psychological intervention developed by the World Health Organization in alleviating psychological stress and preventing the development of mental health problems. The primary outcome was psychological stress, assessed at the 3-month follow-up. Secondary outcomes were depression symptoms, anxiety symptoms, insomnia, positive affect (PA) and self-kindness assessed at the 3-month follow-up. RESULTS: Between November 2021 and April 2022, 270 participants were enrolled and randomly assigned to either SH+ (n = 135) or the control group (n = 135). The SH+ group had significantly lower stress at the 3-month follow-up (b = -1.23, 95% CI = -2.36, -0.10, p = 0.033) compared to the control group. The interaction effect indicated that the intervention effect in reducing stress differed over time (b = -0.89, 95% CI = -1.50, -0.27, p = 0.005). Analysis of the secondary outcomes suggested that SH+ led to statistically significant improvements in most of the secondary outcomes, including depression, insomnia, PA and self-kindness. CONCLUSIONS: This is the first known randomised controlled trial ever conducted to improve stress and mental health problems among healthcare workers experiencing psychological stress in a low-resource setting. SH+ was found to be an effective strategy for alleviating psychological stress and reducing symptoms of common mental problems. SH+ has the potential to be scaled-up as a public health strategy to reduce the burden of mental health problems in healthcare workers exposed to high levels of stress.

Exposure to polystyrene microplastics and perfluorooctane sulfonate disrupt the homeostasis of intact planarians and the growth of regenerating planarians.

Microplastics (MPs) and perfluorinated compounds (PFAS) are widespread in the global ecosystem. MPs have the ability to adsorb organic contaminants such as perfluorooctane sulfonate (PFOS), leading to combined effects. The current work aims to explore the individual and combined toxicological effects of polystyrene (PS) and PFOS on the growth and nerves of the freshwater planarian (Dugesia japonica). The results showed that PS particles could adsorb PFOS. PS and PFOS impeded the regeneration of decapitated planarians eyespots, whereas the combined treatment increased the locomotor speed of intact planarians. PS and PFOS caused significant DNA damage, while co-treatment with different PS concentrations aggravated and attenuated DNA damage, respectively. Further studies at the molecular level have shown that PS and PFOS affect the proliferation and differentiation of neoblasts in both intact and regenerating planarians, alter the expression levels of neuronal genes, and impede the development of the nervous system. PS and PFOS not only disrupted the homeostasis of intact planarians, but also inhibited the regeneration of decapitated planarians. This study is the first to assess the multiple toxicity of PS and PFOS to planarians after combined exposure. It provides a basis for the environmental and human health risks of MPs and PFAS.

Multiple toxicity evaluations of perfluorooctane sulfonate on intact planarian Dugesia japonica.

Perfluorooctane sulfonate (PFOS) is gaining widespread attention as a persistent organic pollutant with multiple mechanisms of toxicity. In this study, PFOS at different concentrations and different exposure times was used to evaluate the multiple toxicities on intact planarian Dugesia japonica. The proliferation of neoblasts, apoptosis, DNA damage and the expression levels of neuronal genes and the major genes of the Wnt pathway were effectively studied. The results demonstrated that the balance between proliferation and apoptosis of intact planarian cells was disrupted after PFOS exposure, which in turn affected tissue homeostasis and differentiation. PFOS exposure led to increased DNA damage and altered neuronal gene expression. In addition, PFOS exposure could down-regulate the expression of Wnt pathway genes, but the inhibition of the Wnt pathway by PFOS was time- and concentration-dependent. These findings suggest that PFOS has multiple toxic effects on planarians and may interfere with cell proliferation and neurodevelopment by affecting the key gene expression in the Wnt pathway, providing estimable information on the neurodevelopmental toxicity and ecotoxicity of PFOS toxicity in aquatic animals and environments.

Pharmacokinetics and Bioequivalence of Two Formulations of Rosuvastatin Following Single-dose Administration in Healthy Chinese Subjects Under Fasted and Fed Conditions.

The main objective of the study was to evaluate the bioequivalence of two rosuvastatin calcium tablets in healthy Chinese subjects under fasted and fed conditions. The study was carried out using a randomized, open-label, two-formulation, two-sequence, two-period, single-dose crossover design, with a washout period of 7 days. Both the fasted study and fed study enrolled 28 subjects. In each study period, the subjects were administrated a single oral dose of the test product or reference product of rosuvastatin 10 mg. Blood samples were collected from pre-dose to 72 hours after administration with 16 time points in total. Bioequivalence evaluation was performed using ln-transformed pharmacokinetic parameters of rosuvastatin, including Cmax , AUC0-t , and AUC0-∞ . In the present study, 95% confidence intervals (CIs) of test/reference geometric mean ratios (GMRs) of Cmax , AUC0-t , and AUC0-∞ under the fasted and fed conditions were all within the acceptance range of 80%-125%. Additionally, only one subject experienced one adverse event (AE). High-fat meals reduced the Cmax , AUC0-t , and AUC0-∞ , but had no significant effects on the λz, t1/2 , or Tmax of rosuvastatin. In the current study, the test product was bioequivalent to the reference product, and a single dose of rosuvastatin (10 mg) was well-tolerated. Food decreased the systemic exposure of rosuvastatin without the effects on the Tmax or elimination rate.

Psychological stress self-help interventions for healthcare workers in the context of COVID-19 in China: A randomized controlled trial protocol.

Background: Public health emergencies may lead to severe psychological stress, especially for healthcare workers, including frontline healthcare workers and public health workers. However, few stress management interventions have been implemented for healthcare workers even though they require more comprehensive interventions than the general public. Self-Help Plus (SH+) is a novel psychological self-help intervention developed by the World Health Organization. It is accessible, scalable, and cost-effective and has the potential to be quickly applied to help people cope with stress and adversity. The major objective of this study is to evaluate the effectiveness of SH+ interventions on the alleviation of stress levels and mental health problems among healthcare workers. Methods: A randomized controlled trial of SH+ will be conducted to investigate the stress level and mental health status of Chinese healthcare workers and control subjects in Guangzhou. Assessments will be performed before (baseline), at the end of (1 month), and 2 months after (3 months) the intervention. After completing the baseline screening questionnaire, eligible participants will be randomly assigned to one of the two groups in a 1:1 ratio by block randomization. During the 1-month intervention period, the intervention group will receive the SH+ intervention and the control group will receive information about mental health promotion. The intervention will be delivered by the research assistant via social media platforms. The primary outcome is the level of stress, which will be measured by a 10-item Perceived Stress Scale. Secondary outcomes including mental health symptoms will also be collected. Discussion: Given the potential for multiple COVID-19 waves and other infectious disease pandemics in the future, we expect that SH+ will be an effective stress management intervention for healthcare workers. The findings from this study will facilitate the application of SH+, and the trial is expected to be extended to a larger population in the future.

Pharmacokinetics and bioequivalence study of two ciprofloxacin hydrochloride tablets in healthy Chinese subjects under fasting and fed conditions: A randomized, open-label, two-formulation, two-sequence, two-period, single-dose crossover study.

OBJECTIVE: The study mainly aimed to determine the bioequivalence of two branded ciprofloxacin hydrochloride tablets (250 mg) under fasting and fed conditions. MATERIALS AND METHODS: The study was carried out in 48 healthy Chinese subjects under fasting and fed conditions with a randomized, open-label, two-formulation, two-sequence, two-period, single-dose crossover design. In each period of the study, the subjects were assigned to receive a single oral dose of 250 mg ciprofloxacin hydrochloride. Blood samples were collected from 1 hour before dosing to 36 hours after administration with 16 timepoints in total. The bioequivalence analysis was performed after ln-transformation of the ciprofloxacin pharmacokinetic parameters including Cmax, AUC0-t, and AUC0-∞. RESULTS: A total of 48 subjects were enrolled in the fasting and fed studies, and 1 of the subjects was excluded before drug administration. In the fasting study, the 90% CIs for the test/reference geometric mean ratios (GMRs) of the ln-transformed data for Cmax, AUC0-t, and AUC0-∞ were 85.41 - 100.97%, 95.40 - 100.27%, and 95.48 - 100.30%, respectively. For the fed study, the 90% CIs for the test/reference GMRs of the ln-transformed data for Cmax, AUC0-t, and AUC0-∞ were 90.15 - 113.75%, 99.10 - 103.77%, and 99.11 - 103.80%, respectively. These values all fell within the standard acceptance range of 80 - 125%. CONCLUSION: In the study, the generic (test) product of ciprofloxacin hydrochloride 250 mg was bioequivalent to the innovator (reference) product after single-, oral-dose administration under fasting and fed conditions.

[Dynamic change of hippocampal volume in children with recurrent febrile seizures].

OBJECTIVE: To study the change and significance of hippocampal volume (HCV) in children with recurrent febrile seizures. METHODS: A retrospective analysis was performed on the medical data and examination results of 34 children with recurrent febrile seizures who underwent two magnetic resonance plain scans of the head and the hippocampus from January 1, 2013 to September 30, 2019. According to the follow-up time, they were divided into the first follow-up group and the second follow-up group. According to prognosis, they were divided into a febrile seizure group, a non-febrile group and an epilepsy group. The change in HCV was analyzed and compared. RESULTS: Total HCV was positively correlated with age (rs=0.683, P < 0.05). The second follow-up group had a significantly larger total HCV than the first follow-up group (P < 0.05). For both groups, preschool children (≥ 3 years old) had significantly larger total HCV, left HCV, and right HCV than those at an age of < 3 years (P < 0.05). For both groups, the children with persistent seizures had significantly lower average annual increment (ΔV) of total HCV, left HCV, and right HCV than those without persistent seizures (P < 0.05). There was no significant difference in ΔV of total HCV, left HCV, and right HCV among the febrile seizure, non-febrile seizure and epilepsy groups (P > 0.05). CONCLUSIONS: HCV gradually increases with age in children with recurrent febrile seizures. Persistent seizures may damage the development of the hippocampus.

Fault Diagnosis for Rotating Machinery Using Multiscale Permutation Entropy and Convolutional Neural Networks.

In view of the limitations of existing rotating machine fault diagnosis methods in single-scale signal analysis, a fault diagnosis method based on multi-scale permutation entropy (MPE) and multi-channel fusion convolutional neural networks (MCFCNN) is proposed. First, MPE quantitatively analyzes the vibration signals of rotating machine at different scales, and obtains permutation entropy (PE) to construct feature vector sets. Then, considering the structure and spatial information between different sensor measurement points, MCFCNN constructs multiple channels in the input layer according to the number of sensors, and each channel corresponds to the MPE feature sets of different monitored points. MCFCNN uses convolutional kernels to learn the features of each channel in an unsupervised way, and fuses the features of each channel into a new feature map. At last, multi-layer perceptron is applied to fuse multi-channel features and identify faults. Through the health monitoring experiment of planetary gearbox and rolling bearing, and compared with single channel convolutional neural networks (CNN) and existing CNN based fusion methods, the proposed method based on MPE and MCFCNN model can diagnose faults with high accuracy, stability, and speed.

Large-scale optimization of multi-pollutant control strategies in the Pearl River Delta region of China using a genetic algorithm in machine learning.

A scientifically sound integrated assessment modeling (IAM) system capable of providing optimized cost-benefit analysis is essential in effective air quality management and control strategy development. Yet scenario optimization for large-scale applications is limited by the computational expense of optimization over many control factors. In this study, a multi-pollutant cost-benefit optimization system based on a genetic algorithm (GA) in machine learning has been developed to provide cost-effective air quality control strategies for large-scale applications (e.g., solution spaces of ~1035). The method was demonstrated by providing optimal cost-benefit control pathways to attain air quality goals for fine particulate matter (PM2.5) and ozone (O3) over the Pearl River Delta (PRD) region of China. The GA was found to be >99% more efficient than the commonly used grid searching method while providing the same combination of optimized multi-pollutant control strategies. The GA method can therefore address air quality management problems that are intractable using the grid searching method. The annual attainment goals for PM2.5 (< 35 µg m-3) and O3 (< 80 ppb) can be achieved simultaneously over the PRD region and surrounding areas by reducing NOx (22%), volatile organic compounds (VOCs, 12%), and primary PM (30%) emissions. However, to attain stricter PM2.5 goals, SO2 reductions (> 9%) are needed as well. The estimated benefit-to-cost ratio of the optimal control strategy reached 17.7 in our application, demonstrating the value of multi-pollutant control for cost-effective air quality management in the PRD region.

Bearing Fault Diagnosis with a Feature Fusion Method Based on an Ensemble Convolutional Neural Network and Deep Neural Network.

Rolling bearings are the core components of rotating machinery. Their health directly affects the performance, stability and life of rotating machinery. To prevent possible damage, it is necessary to detect the condition of rolling bearings for fault diagnosis. With the rapid development of intelligent fault diagnosis technology, various deep learning methods have been applied in fault diagnosis in recent years. Convolution neural networks (CNN) have shown high performance in feature extraction. However, the pooling operation of CNN can lead to the loss of much valuable information and the relationship between the whole and the part may be ignored. In this study, we proposed CNNEPDNN, a novel bearing fault diagnosis model based on ensemble deep neural network (DNN) and CNN. We firstly trained CNNEPDNN model. Each of its local networks was trained with different training datasets. The CNN used vibration sensor signals as the input, whereas the DNN used nine time-domain statistical features from bearing vibration sensor signals as the input. Each local network of CNNEPDNN extracted different features from its own trained dataset, thus we fused features with different discrimination for fault recognition. CNNEPDNN was tested under 10 fault conditions based on the bearing data from Bearing Data Center of Case Western Reserve University (CWRU). To evaluate the proposed model, four aspects were analyzed: convergence speed of training loss function, test accuracy, F-Score and the feature clustering result by t-distributed stochastic neighbor embedding (t-SNE) visualization. The training loss function of the proposed model converged more quickly than the local models under different loads. The test accuracy of the proposed model is better than that of CNN, DNN and BPNN. The F-Score value of the model is higher than that of CNN model, and the feature clustering effect of the proposed model was better than that of CNN.

An exploratory model for the non-fatal drowning risks in children in Guangdong, China.

BACKGROUND: Drowning is a leading cause of accidental death in children under 14 years of age in Guangdong, China. We developed a statistical model to classify the risk of drowning among children based on the risk factors. METHODS: A multiple-stage cluster random sampling was employed to select the students in Grades 3 to 9 in two townships in Qingyuan, Guangdong. Questionnaire was a self-reported measure consisting of general information, knowledge, attitudes and activities. A univariate logistic regression model was used to preliminarily select the independent variables at a P value of 0.1 for multivariable model. Three-quarters of the participants were randomly selected as a training sample to establish the model, and the remaining were treated as a testing sample to validate the model. RESULTS: A total of 8390 children were included in this study, about 12.18% (1013) experienced drowning during the past one year. In the univariate logistic regression model, introvert personality, unclear distributions of water areas on the way to school, and bad relationships with their classmates and families were positively associated with drowning. However, females, older age and lower swimming skills were negatively associated with drowning. After employing the prediction model with these factors to estimate drowning risk of the students in the testing samples, the results of Hosmer-Lemeshow tests showed non-significant differences between the predictive results and actual risk (χ2 = 5.97, P = 0.65). CONCLUSIONS: Male, younger children, higher swimming skills, bad relationship with their classmates and families, introvert personality and unclear distributions of water areas on the way to school were important risk factors of non-fatal drowning among children. The prediction model based on these variables has an acceptable predictive ability.

Effects of air pollution control measures on air quality improvement in Guangzhou, China.

The ambient air quality of Guangzhou in 2016 has significantly improved since Guangzhou and its surrounding cities implemented a series of air pollution control measures from 2014 to 2016. This study not only estimated the effects of meteorology and emission control measures on air quality improvement in Guangzhou but also assessed the contributions of emissions reduction from various sources through the combination of observation data and simulation results from Weather Research and Forecasting - Community Multiscale Air Quality (WRF-CMAQ) modeling system. Results showed that the favorable meteorological conditions in 2016 alleviated the air pollution. Compared to change in meteorology, implementing emission control measures in Guangzhou and surrounding cities was more beneficial for air quality improvement, and it could reduce the concentrations of SO2, NO2, PM2.5, PM10, and O3 by 9.7 µg m-3 (48.4%), 9.2 µg m-3 (17.7%), 7.7 µg m-3 (14.6%), 9.7 µg m-3 (13.4%), and 12.0 µg m-3 (7.7%), respectively. Furthermore, emission control measures that implemented in Guangzhou contributed most to the concentration reduction of SO2, NO2, PM2.5, and PM10 (46.0% for SO2, 15.2% for NO2, 9.4% for PM2.5, and 9.1% for PM10), and it increased O3 concentration by 2.4%. With respect to the individual contributions of source emissions reduction, power sector emissions reduction showed the greatest contribution in reducing the concentrations of SO2, NO2, PM2.5, and PM10 due to the implementation of Ultra-Clean control technology. As for O3 mitigation, VOCs product-related source emissions reduction was most effective, and followed by transportation source emissions reduction, while the reductions of power sector, industrial boiler, and industrial process source might not be as effective. Our findings provide scientific advice for the Guangzhou government to formulate air pollution prevention and control policies in the future.

Geodermatophilus daqingensis sp. nov., isolated from petroleum-contaminated soil.

A novel Gram-positive actinobacterium, designated WT-2-1T, was isolated from a sample of petroleum-contaminated soil collected in Daqing, Heilongjiang province, China and characterised using a polyphasic taxonomic approach. The optimal growth for strain WT-2-1T was found to be at 25-35 °C and at pH 6.0-9.0 and with 0-4% (w/v) NaCl, forming blackish green-coloured colonies. Chemotaxonomic and molecular characteristics of the isolate match those described for members of the genus Geodermatophilus. The peptidoglycan was found to contain meso-diaminopimelic acid; galactose, glucose and xylose were detected as diagnostic sugars. The main phospholipids were identified as diphosphatidylglycerol, phosphatidylcholine, phosphatidylinositol, phosphatidylethanolamine and phosphatidylglycerol; MK-9(H4) was the dominant menaquinone present. The major cellular fatty acids were identified as iso-C16:0 and iso-C15:0. 16S rRNA gene sequence analysis showed that strain WT-2-1T is a member of the genus Geodermatophilus, with high sequence similarities to Geodermatophilus aquaeductus BMG801T (98.4%), Geodermatophilus saharensis CF5/5T (98.4%), Geodermatophilus bullaregiensis BMG841T (98.3%) and Geodermatophilus normandii CF5/3T (98.3%). Based on the phenotypic characteristics, phylogenetic data and DNA-DNA hybridization results, the isolate is concluded to represent a novel species of the genus Geodermatophilus, for which the name Geodermatophilus daqingensis sp. nov. is proposed. The type strain is WT-2-1T (=CGMCC 4.7381T = DSM 104001T).

Chemokine receptor 7 enhances cell chemotaxis and migration of metastatic squamous cell carcinoma of head and neck through activation of matrix metalloproteinase-9.

The mechanisms leading to squamous cell carcinoma of head and neck (SCCHN) metastasis are not fully understood. Although evidence shows that the chemokine receptor 7 (CCR7) and its ligand CCL19 may regulate tumor dissemination, their role is not clearly defined in SCCHN. Matrix metalloproteinases break consisting of tissue barrier to the surrounding tissue invasion and metastasis by destroying the balance of matrix degradation of the basement membrane of tumor cells and extracellular matrix (ECM). We used chemotaxis and migration assays, western blotting, gelatin zymography, actin polymerization assay, immunofluorescence staining and immunohistochemical analysis to explore whether MMP-9 can be activated by CCL19 (CCR7's ligand) and its role in SCCHN. The experiments were performed in the metastatic SCCHN cell line PCI-37B after pre-incubation of the cells with CCL19 and SB-3CT (inhibitor of MMP-9). Our results demonstrated that CCR7 favors PCI-37B cell chemotaxis and migration, upregulation of MMP-9 protein and motivates the activity of MMP-9 protein, induces reorganization of the actin cytoskeleton and upregulation of MMP-9 protein. SB-3CT can block all these effects. Collectively, our data indicated that CCR7 regulates cell chemotaxis and migration via MMP-9 in metastatic SCCHN, and these results provide a basis for new strategies in preventing metastases of SCCHN.

Infection status and risk factors of HIV, HBV, HCV, and syphilis among drug users in Guangdong, China--a cross-sectional study.

BACKGROUND: China has witnessed a remarkable increase in sexually transmitted infections (STIs) and HIV. The study is to assess the prevalence of HIV, HBV, HCV and syphilis and related risk factors among drug users in mandatory detoxification center Qingyuan, Guangdong, China. METHOD: A cross-sectional study on drug use behaviors, sex behaviors, and presence of antibodies to HIV, HCV, Treponema pallidum, and surface antigen of HBV (HBsAg) was conducted among drug users recruited from 3 detoxification centers in Qingyuan, Guangdong, China. Risk factors for each of four infections were analyzed with logistic regression model. RESULTS: A total of 740 subjects were recruited, the median age was 31 years old (range 24-38). The seroprevalence rates of HIV, HBsAg, HCV and syphilis were 4.6%, 19.3%, 71.6% and 12.6%, respectively. Risk factors for HIV were intravenous drug use and co-infection with syphilis. Having a regular sexual partner who was a drug user was considered to be a risk factor for HBV. Intravenous drug use was a risk factor for HCV. However, the consistent use of condoms with commercial sex partners was protective for HCV infection. Compared to drug users living in urban area, those living in rural areas were more likely to be infected with syphilis, and there was an association between commercial sex and syphilis. CONCLUSION: The prevalence of HIV, HBV, HCV and syphilis were high among drug users in detoxification centers in Qingyuan, thus, risk reduction programs for the drug user population is urgently required.

[The properties of OTFTs and pentacene films deposited onto different insulator layers].

The authors fabricated OTFT devices with different insulator materials. The OTFTs with PMMA as the dielectric layer exhibit better properties, including a mobility of 0.207 cm2 x V1 x s(-1), an on/off current ratio of 4.93 x 10(3), and a threshold voltage of 4.3 V. However, the OTFTs based on oxidized silicon dielectric layer perform not so well, with a mobility of 0.039 cm2 x V(-1) x s(-1), an on/off current ratio of 5.98 x 10(2), and a threshold voltage of 5.4 V. In order to explain the difference in performances, we compared the surface roughness of the oxidized silicon film with that of the PMMA film according to the results of atomic force microscopy, and found that the former had a roughness mean square (RMS) of 1.579 nm and the latter was more smooth with an RMS of 0.216 nm. The quality of the pentacene films deposited onto oxidized silicon and PMMA was also studied by atomic force microscopy and X-ray diffraction. From the results of AFM, the authors found that the pentacene film deposited on PMMA had high thin film quality with larger grain size and less crystal grain boundaries. From the results of XRD, the authors found that the pentacene film deposited on PMMA had clear diffraction peak, showing that the pentacene film deposited on PMMA had greater crystallite quality once again. Therefore, OTFTs with PMMA as insulator layers have advantages over those OTFTs with oxidized silicon dielectric layer.