[Epidemiological characteristics of a 2019-nCoV outbreak caused by Omicron variant BF.7 in Shenzhen]

Objective: To explore the epidemiological characteristic of a COVID-19 outbreak caused by 2019-nCoV Omicron variant BF.7 and other provinces imported in Shenzhen and analyze transmission chains and characteristics. Methods: Field epidemiological survey was conducted to identify the transmission chain, analyze the generation relationship among the cases. The 2019-nCoV nucleic acid positive samples were used for gene sequencing. Results: From 8 to 23 October, 2022, a total of 196 cases of COVID-19 were reported in Shenzhen, all the cases had epidemiological links. In the cases, 100 were men and 96 were women, with a median of age, M (Q₁, Q₃) was 33(25, 46) years. The outbreak was caused by traverlers initial cases infected with 2019-nCoV who returned to Shenzhen after traveling outside of Guangdong Province.There were four transmission chains, including the transmission in place of residence and neighbourhood, affecting 8 persons, transmission in social activity in the evening on 7 October, affecting 65 persons, transmission in work place on 8 October, affecting 48 persons, and transmission in a building near the work place, affecting 74 persons. The median of the incubation period of the infection, M (Q₁, Q₃) was 1.44 (1.11, 2.17) days. The incubation period of indoor exposure less than that of the outdoor exposure, M (Q₁, Q₃) was 1.38 (1.06, 1.84) and 1.95 (1.22, 2.99) days, respcetively (Wald χ²=10.27, P=0.001). With the increase of case generation, the number and probability of gene mutation increased. In the same transmission chain, the proportion of having 1-3 mutation sites was high in the cases in the first generation. Conclusions: The transmission chains were clear in this epidemic. The incubation period of Omicron variant BF.7 infection was shorter, the transmission speed was faster, and the gene mutation rate was higher. It is necessary to conduct prompt response and strict disease control when epidemic occurs.

[Correlation between both neck/shoulder and low back pain and daily behavioral habits among middle school students in Shenzhen]

Objective: To study the relations between neck/shoulder or low back pain and their daily behavioral habits among middle school students in Shenzhen. Methods: We randomly chose 3 952 students from 10 high schools in Shenzhen to complete the questionnaires. Data was gathered and analyzed, using the IBM SPSS 23.0. Results: Of the 3 952 participants, 20.3% had neck/shoulder pain and 15.2% had low back pain. Among students experienced neck/shoulder pain, female (25.3%), high school (24.5%) and boarding students (24.4%) experienced higher rates of neck/shoulder pain (P<0.05). Female students (17.9%) also had higher rate of low back pain (P<0.05). Results from logistic regression analysis showed that factors as: gender, type of school, taking naps on the desk, staying up late, self-perceived stress from learning, overloading homework, time spent on mobile phone and TV, spending long time on computer etc. were related to the neck/shoulder pain (P<0.05). Factors as: gender, naps on the desk, stay up late, self-perceived stress, overloading homework, time spent on mobile phone and TV etc., were related to low back pain (P<0.05). Conclusion: Neck/shoulder pain and low back pain were both commonly seen while high self-perceived stress, sedentary behaviors and poor sleeping habits were associated with both neck/shoulder and low back pain in high school students in Shenzhen.

Natural attenuation model and biodegradation for 1,1,1-trichloroethane contaminant in shallow groundwater

Natural attenuation is an effective and feasible technology for controlling groundwater contamination. This study investigated the potential effectiveness and mechanisms of natural attenuation of 1,1,1-trichloroethane (TCA) contaminants in shallow groundwater in Shanghai by using a column simulation experiment, reactive transport model, and 16S rRNA gene clone library. The results indicated that the majority of the contaminant mass was present at 2–6 m in depth, the contaminated area was approximately 1000 m × 1000 m, and natural attenuation processes were occurring at the site. The effluent breakthrough curves from the column experiments demonstrated that the effectiveness of TCA natural attenuation in the groundwater accorded with the advection-dispersion-reaction equation. The kinetic parameter of adsorption and biotic dehydrochlorination of TCA was 0.068 m³/kg and 0.0045 d^–1. The contamination plume was predicted to diminish and the maximum concentration of TCA decreased to 280 μg/L. The bacterial community during TCA degradation in groundwater belonged to Trichococcus, Geobacteraceae, Geobacter, Mucilaginibacter, and Arthrobacter.

Effects of electrokinetic treatment of contaminated sludge on migration and transformation of Cd, Ni and Zn in various bonding states

This study assesses the effect of electrokinetic processes on the migration and bonding states of various heavy metals in municipal sludge. The transformation and migration are discussed through the examination of sludge characteristics and distribution of Cd, Zn and Ni after electrokinetic treatments. The migration and distribution of the contaminants after the electrokinetic treatments were determined for each sludge sample by sequential extraction. The noticeable changes on the average speciation fractions of Cd, Zn and Ni were observed that oxidizable heavy metals increased and reducible fraction decreased due to the application of voltage. Bivariate correlation analysis indicated that the amounts of different bonding states of Zn and Ni were significantly correlated (P<0.05) with durations and resistance. The oxidizable Zn was negatively correlated with exchangeable and reducible Zn. Moreover, reducible Zn had a close negative relationship with residual Zn. The bonding state of Ni was significantly related to the durations of electrokinetic processes, indicating the existing of mutual transformation between different speciation fractions over time. The analysis also indicated that the exchangeable Cd showed a close negative relationship with reducible Cd (P<0.01), whereas the reducible Cd was negatively related to residual Cd (P<0.05).

[Stabilization and long-term effect of chromium contaminated soil]

Short-term (3 d and 28 d) and long-term (1 a) stabilization effects of Cr contaminated soil were investigated through nature curing, using four amendments including ferrous sulfide, ferrous sulfate, zero-valent iron and sodium dithionite. The results indicated that ferrous sulfide and zero-valent iron were not helpful for the stabilization of Cr(VI) when directly used because of their poor solubility and immobility. Ferrous sulfate could effectively and rapidly decrease total leaching Cr and Cr(VI) content. The stabilization effect was further promoted by the generation of iron hydroxides after long-term curing. Sodium dithionite also had positive effect on soil stabilization. Appropriate addition ratio of the two chemicals could help maintain the soil pH in range of 6-8.

[Effect of desilication treatment using silicate bacteria on the bioleaching efficiency of municipal solid waste incineration fly ash]

One silicate bacteria strain SDB6 with good performance in silicon removal was isolated and screened from soil. Based on the morphological, physiological, biochemical characteristics and 16S rDNA sequence analysis, SDB6 was identified as Bacillus mucilaginosus strain. The effects of nitrogen source, pH, temperature, rotate speed and medium volume on the growth of SDB6 were investigated. The above factors were optimized using the orthogonal design. The optimized condition was described as follows: 10 g/L yeast, 250 mL flask with 50 mL culture medium, pH 7.5, 30 degrees C, 180 r/min. The bioleaching of un-desilicated and desilicated fly ash using the adapted Aspergillus niger AS 3.879M strain was carried out for 20d. The results indicated that the metal extraction yield in bioleaching increased obviously with desilication treatment comparing to that without desilication treatment. The extraction yield of Cu, Mn, Cr, Zn and Fe from desilicated fly ash was 31%, 75%, 60%, 60% and 48%, respectively. The total metals extraction yield of desilicated fly ash increased to 50%. The TCLP results of the fly ash after bioleaching indicated that the leaching toxicities of the treated fly ash were far lower than the regulated levels of China and permitted to the further landfill or reuse.

[Movement-adsorption and its mechanism of Cd in soil under combining effects of electrokinetics and a new type of bamboo charcoal]

The characteristics of migration and its influencing factor of cadmium in sandy loam soil by uniform electrokinetics as well as the adsorption property by a new material-bamboo charcoal were investigated through bench-scale experiments, and the feasibility of using electrokinetic technique combined with the newly developed bamboo charcoal for remediation of cadmium contaminated soils was analyzed as well. The results show that the bamboo charcoal is good adsorption material which has comparably strong adsorption effect on Cd, bearing potential in future use, which could be simulated by both Freundlich and Langmuir models (R2 > 0.96). The migration rates of cadmium in sandy loam were high up to 0. 6786 - 0.6875cm/h under an electric gradient of 1.0V/cm, depending upon the concentration of cadmium and the distribution of electric field density. Electrokinetics effectively transported the heavy metal in the soil. In the new electrokinetic tech combining the bamboo charcoal with the same electric gradient above under the polarity reversal period of 48 hours, the cadmium in the soil could be wiped off with high efficiency (removal efficiency 79.6% in 12 days) and the pH together with water content could be well retained. The electric current in the process changed periodically according to the reversal. As a new technique, the electrokinetic movement-bamboo charcoal adsorption holds high potential in future use.

Effects of tetrandrine on changes of NMDA receptor channel in cortical neurons of rat induced by anoxia

AIM

To study the effects of tetrandrine (Tet) on the changes of NMDA receptor channels in cortical neurons induced by anoxia.

METHODS

Cell-attached configuration of patch-clamp techniques. Anoxia was produced by perfused cells with 95% N2 + 5% CO2 gassed bath solution.

RESULTS

During anoxia, the open time constant (tau 2), open probability (Po) of 35-pS and 100-pS channels increased. Tet 7.5 mumol.L-1 reduced the Po of 35-pS and 100-pS channels, 15 and 30 mumol.L-1 inhibited open of 100-pS channel fully, and changed the open time constant of 35-pS from two to single exponential distribution.

CONCLUSION

Tet inhibition of the open of NMDA receptor channels induced by anoxia was one of its protective mechanisms.

Risk of lung cancer among cigarette and pipe smokers in southern China

Studies in Shanghai and in north-east China indicate that cigarette smoking is a major contributor to the high rates of lung cancer in those areas, but doubts persist regarding the influence of cigarette use on lung cancer rates in other areas of China. In addition, the risk of lung cancer associated with other methods of tobacco consumption--in particular, the use of bamboo water-pipes and long-stem pipes--is uncertain. A population-based case-control study of 427 male lung cancer patients residing in a mining area of Southern China and 1,011 controls was carried out to address this and other issues. Of these patients, 63% smoked cigarettes and (water and long-stem) pipes; 17% and 14% smoked only cigarettes or pipes, respectively; and 6% did not smoke. Compared to non-smokers, smokers of cigarettes only, smokers of pipes only and mixed smokers were at increased risk; OR = 2.6 (95% CI 1.1-6.2), 1.8 (95% CI 0.8-4.2) and 4.1 (95% CI 2.3-9.2), respectively. Risk increased with duration of tobacco use; however, the rate of increase with years of cigarette use was significantly greater than for years of pipe use (p = 0.03). In addition, risks increased 8-fold in the highest quartile of number of cigarettes per day compared to non-cigarette smokers vs. 2.3-fold for the highest quartile of number of liang (50 g) smoked per month compared to non-pipe-smokers; the trends in the ORs differed significantly (p less than 0.001). Results suggest that, in this area of China, tobacco use is an important cause of lung cancer, and that smoking cigarettes may be more deleterious than smoking pipes (primarily water pipes).

Dietary determinants of lung-cancer risk: results from a case-control study in Yunnan Province, China

The relation between diet and lung cancer was studied among male residents of a mining community in Yunnan Province. After obtaining food frequency data from subjects or proxies, we compared diets of 428 cases, aged 35-74 years, and 1,011 age-matched controls. Cases tended to consume slightly more rice, but less protein-rich foods (i.e., bean curd, meat, eggs) and vegetables than did controls. The relative risks of lung cancer across increasing quartiles of meat (i.e., pork) consumption, for example, were 1.00, 0.67, 0.72 and 0.46 (p for trend less than 0.01). The relative risks of lung cancer across increasing quartiles of consumption of dark-green, leafy vegetables were 1.00, 0.62, 0.52 and 0.41 (p for trend less than 0.01). Although specific dietary constituent(s) responsible for the protective effect of vegetable consumption could not be identified, carotenoids other than beta-carotene, or compounds in cruciferous or Allium vegetables, are possibilities.