The lead and cadmium content in rice and risk to human health in China: A systematic review and meta-analysis.

Numerous studies have investigated concentrations of lead (Pb) and cadmium (Cd) in rice in China, but have come to divergent conclusions. Therefore we systematically reviewed and meta-analyzed the available evidence on levels of Pb and Cd in rice in different regions of China in order to assess the potential risk to human health. The meta-analysis included 24 studies of Pb levels and 29 studies of Cd levels, published in 2011-2021. The pooled Pb concentration in rice was 0.10 mg per kg dry weight (95% CI 0.08-0.11), while the pooled Cd concentration was 0.16 mg per kg dry weight (95% CI 0.14-0.18). These levels are within the limits specified by national food safety standards. However, the total target hazard quotient for both metals exceeded 1.0 for adults and children, suggesting that rice consumption poses a health risk.

Research on Key Technologies to Improve Cementing Displacement Efficiency.

The annulus has a wide and narrow clearance due to casing eccentricity in the cementing process and due to the eccentricity of casing in the process of cementing. Because the flow resistance of the drilling fluid in the wide gap is less than that in the narrow gap, the phenomena of a delayed flow or even an overall nonflow occurs in the narrow gap. Based on the existing displacement efficiency calculation model, this paper establishes the cementing displacement efficiency model under the condition of oil-based drilling fluid, explores the residual layer thickness of drilling fluid on the casing side and the sidewall side, and then links the annular displacement efficiency to the injection displacement in combination with the circulating mode resistance pressure drop formula so as to explore the change in the cementing displacement efficiency under different displacements. Considering the change in the physical parameters of annulus fluid, the change in annulus displacement efficiency is obtained. On this basis, the relationship between the wellhead cement injection flow and the annulus retention layer is studied; then, the displacement is calculated. The reasonable cementing displacement is calculated by combining the displacement with annulus displacement efficiency. The results show that the thickness of the annular detention layer increases with the increase in the casing eccentricity in the same well depth, and the growth rate of the detention layer on the wellbore side is greater than that on the casing side at the same circumferential angle. The greater the displacement, the greater the annular circulation pressure drop and circulation equivalent density, thus increasing the cementing risk. The displacement is reasonably designed. The research results in this paper have a certain guiding significance for improving the displacement rate of isolation fluid under oil-based drilling fluid conditions.

Evaluation of Flushing Ability of Cementing Flushing Fluids.

During cementing operation with oil-based drilling fluids, the casing and well wall are in the "oil wet" environment, and the cement slurry cannot achieve good cementation with the second interface, which seriously affects the cementation quality of the cementing interface. Therefore, it is very important to select a flushing fluid with good performance and high flushing efficiency for cementing operation with an oil-based drilling fluid. An integrated measurement system of interface parameters and a rotating liquid interface tension tester is selected in the room. A set of evaluation methods of wetting reversal is developed to evaluate the wetting reversal ability of type A and type-B flushing fluids on site to optimize the reasonable type and concentration of the flushing fluid. The experimental results show that under the same concentration, the surface tension and interfacial tension of type A flushing solution are lower than those of type-B; that is, the hydrophilic effect of type A flushing solution is better than that of type-B. The wettability reduction of type A is better than that of type-B. The wetting reversal ability of type A flushing solution with a surfactant concentration of 30% is better than that of type-B. The evaluation methods include surface tension, interface tension, dewetting ability, and oil washing ability of the flushing fluid, and the evaluation of the wetting reversal ability is carried out on the basis of the sandstone, sheet metal (steel for three open casings on site), and slide glass (as a reference). Then, according to the optimal concentration of the flushing fluid, a mixing experiment of the two kinds of flushing fluids is carried out to evaluate the ability of wetting reversal, and compared with the experimental results of A and B, the reasonable flushing fluid formula is finally selected. A proper analysis of the adaptability of the evaluation method of the flushing fluid is conducive to the reliable evaluation of the performance of the flushing fluid and the enhancement of the operator's ability to grasp the cementing quality. To guide the field practice has a very important practical significance, but it also has a guiding role for the development of new pre-liquid products.

Chitosan oligosaccharide combined with running benefited the immune status of rats.

Chitosan oligosaccharide (COS) degraded by chitosan, is an easily accessible and biocompatible natural molecule, which can facilitate the immune system. Running is one of the most effective forms of exercise. Persistence in running can effectively improve the body's resistance against pathogens. However, whether the combination of COS and running could benefit immune status still remains to be elucidated. We used Sprague-Dawley (SD) rats to explore the combinatory effect of COS and running. The organs and blood of the rats were collected after four weeks and the organ body mass index, biochemical and blood routine examination, cytokines, and T cells in the spleen and blood were detected and analyzed. In the group intragastric administration of COS only, the level of blood lactate dehydrogenase was increased, while the blood creatinine, red blood cells, lymphocytes, and serum TNF were decreased. Furthermore, COS combined with running promoted the development of spleen and lung, the level of lymphocytes, T cell and CD8+ T cell ratio in the blood, and serum TNF level. At the same time, the level of lactate dehydrogenase, serum IL-2, and T cell ratio in spleen were decreased. Therefore, our study indicated that COS combined with running could improve the immune status of rats.

Chitosan combined with swimming promotes health in rats.

PURPOSE: Chitosan is an easily accessible and biocompatible natural molecule which facilitate the immune system. In recent studies, chitosan is being applied to the drug nanosphere to deliver drugs. However, whether chitosan could promote health under exercising condition remains yet to be elucidated. Hence, we designed to investigate the effect of chitosan on swimming rats. METHODS: Sprague-Dawley (SD) rats were divided into four groups, exercise with chitosan, exercise with water, sedentary with chitosan, and sedentary with water. After four weeks of exercise and chitosan/water gavage, the blood was collected, and its biochemical index, complete blood count, and related parameters, and cytokines were detected and analyzed. RESULTS: The level of blood urea nitrogen (p = 0.0380), total cholesterol (p = 0.048), and low-density lipoprotein (p = 0.0338) were decreased, while the number of red blood cells (p = 0.001), hematocrit (p = 0.01), and mean corpuscular volume (p = 0.039) were increased in chitosan group. Furthermore, the combination of chitosan and swimming decreased the red blood cells distribution width. CONCLUSIONS: Our study support that chitosan could facilitate the health during exercise.