Search

With the rapid development of global industrialization, the pollution of hexavalent chromium (Cr(Ⅵ)) in soil and groundwater has become increasingly serious. Field investigation and laboratory tests were carried out for the soil polluted by the chromium slag of a ferroalloy plant. The adsorption, infiltration and dispersion experiments were conducted to study the adsorption characteristics and migration mechanism of Cr(Ⅵ) in silty clay. A three-dimensional kinetic mathematical model of Cr(Ⅵ) migration considering convection-dispersion-adsorption was established. The migration and distribution characteristics of Cr(Ⅵ) in groundwater with the pollution source located upstream or downstream of the contaminated site were obtained using the numerical approach. Meanwhile, the effects of dispersity and distribution coefficient) on the spatial and temporal distribution of Cr(Ⅵ) were revealed. The experimental results show that the Langmuir isotherm model well fits the adsorption data of silty clay. The maximum adsorption capacity of silty clay for Cr(Ⅵ) was 466.6 mg/kg. The hydraulic conductivity of silty clay under the infiltration of distilled water and 160 mg/L Cr(Ⅵ) solution was 6.5×10–7–6.7×10–7 cm/s, while it increased to 4.4×10–6 cm/s under infiltration of Cr(Ⅵ) solution with a concentration of 1 000 mg/L. The hydrodynamic dispersion coefficient (D) of silty clay was 1.4×10–4 m2/d. The value of the retardation factor ( ) was found to be 4.2–10. The results of the numerical simulation indicated that when the downstream was contaminated by Cr(Ⅵ), there was still a risk of pollution in the upstream even if molecular diffusion was not considered. The degree of pollution depended on the dispersity of the aquifer. Considering the adsorption of Cr(Ⅵ) by the aquifer, the higher the soil distribution coefficient, the smaller was the distribution range of the Cr(Ⅵ) pollution plume. Therefore, the transformation processes such as Cr(Ⅵ) adsorption should be focused on when predicting the distribution of Cr(Ⅵ) in contaminated sites.

It is a promising strategy to prepare composite photocatalysts based on MOFs and semiconductors for enhancing photocatalytic reduction of carbon dioxide (CO 2 ). A family of binary composite photocatalysts ( CdS@UiO-66-NH 2 ) with different CdS contents have been designed and synthesized, which have been explored for photocatalytic reduction of CO 2 . CdS@UiO-66-NH 2 can efficiently convert CO 2 into CO under visible light irradiation via the solid-gas mode in the absence of sacrificial agents and photosensitizers. The generation rate of CO can reach up to 280.5 μmol g -1 h -1 , which is 2.13-fold and 2.9-fold improvements over the pristine CdS and UiO-66-NH 2 , respectively, and the selectivity for CO is very high. Furthermore, this kind of photocatalysts can still maintain great photocatalytic activity in CO 2 /N 2 mixed atmosphere with different CO 2 concentrations. The outstanding performances of CdS@UiO-66-NH 2 may be attributed to the existence of the direct Z-scheme heterojunction, which possesses the enhanced separation and migration of photo-generated charge carriers between UiO-66-NH 2 and CdS, available specific surface areas and improved visible light absorption ability as well as abundant reaction active sites. This case reveals that MOF-based composite photocatalysts exhibit promising potential applications in the field of CO 2 conversion.

Photoreduction of carbon dioxide (CO 2 ) provides an effective perspective for solving the energy crisis and environmental problems. Herein, two types of composite photocatalysts (TiO 2 /ZIF-8) based on ZIF-8 and TiO 2 have been designed and synthesized with the help of the grinding method and the solid-synthesis method. Both composite photocatalysts are employed for the photocatalytic reduction of CO 2 . In composite photocatalysts prepared by the grinding method, ZIF-8 particles are distributed on the surface of TiO 2 , and provide extra available spaces for storing CO 2 , which is beneficial for improving their photoreduction performances. As a result, an enhanced CO formation rate of 21.74 μmol g -1 h -1 with a high selectivity of 99% is obtained for this family of composite photocatalysts via the solid-gas mode without photosensitizers and sacrificial agents. For comparison, the other family of composite photocatalysts synthesized via the solid-synthesis method possesses structures similar to ZIF-8, where TiO 2 is encapsulated inside the framework of ZIF-8. This structural feature obstructs the contact between the active sites of TiO 2 and CO 2 , and leads to lower activities. The best CO formation rate of this family is only 10.67 μmol g -1 h -1 with 90% selectivity. Both the structural features of the two families of photocatalysts are described to explain their differences in photoreduction performances. The experimental finding reveals that different synthetic approaches indeed result in diversified structures and varied photocatalytic performances. This work affords a new scalable and efficient approach for the rational design of efficient photocatalysts in the area of artificial photosynthesis., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Aim: To gain a better understanding of possible factors that may influence the decision of diabetes persons to participate in annual eye screening in an urban community setting of China., Methods: A structured interview including questions on attendance of eye screening, knowledge and awareness of diabetic retinopathy was conducted. The presence and degree of retinopathy were assessed using two field non-mydriatic retinal photography., Results: Totally 720 diabetes persons were recruited and 519 were enrolled in this cross-sectional study. In this urban setting of Beijing, among diabetes patients of average of 10y duration, 77% confirmed having undergone at least one eye examination and 61% reported having at least one eye examination with dilated pupil. As for the last 12mo, the number decreased to 210 (47%) and 131 (30%) separately. Most of the participants (95%) were aware that diabetes could affect their vision and that regular eye examination was necessary. Very few of them (12%) however were aware that the early stages of diabetic retinopathy presented without symptoms of vision loss. Having attended patient education on diabetes was effective in building awareness about diabetic eye disease and was a significant positive predictor for attending eye screening [education in a year, Adj. OR=0.47 (0.29-0.74), P <0.001, education years ago, Adj. OR=0.56 (0.33-0.96), P =0.036]. The duration of disease also increased the likelihood of having undergone eye screening (Adj. OR=0.96, P <0.05)., Conclusion: Being exposed to education about the complications of diabetes increases the probability of attending diabetic eye screening. An appropriate patient knowledge building strategy should be made available to patients from the time of diagnosis.

Objective: The pathogenesis of minimal change nephrotic syndrome (MCNS) remains unclear. This study aimed to investigate the expression of interleukin-6 (IL-6) in rats with doxorubicin-induced nephropathy and its possible roles in the pathogenesis of MCNS., Methods: Eighty-three male Wistar rats were randomly assigned into a control group (n=32) and a nephropathy group (n=51). Nephropathy was induced by a single tail vein injection of doxorubicin (5 mg/kg). The control group was injected with normal saline. Twenty-four-hour urinary protein excretion was measured 7, 14, 28 and 42 days after doxorubicin injection. IL-6 expression in urine and renal tissues was determined using ELISA 7, 14, 28 and 42 days after doxorubicin injection., Results: The urinary protein excretion increased significantly in the nephropathy group 7, 14, 28 and 42 days after doxorubicin injection compared with that in the control group (P<0.01). IL-6 expression in urine and renal tissues increased significantly 7, 14, 28 and 42 days after doxorubicin injection compared with that in the control group (P<0.01). IL-6 expression in urine and renal tissues was positively correlated with 24-hour urinary protein excretion in the nephropathy group (r=0.794, P<0.01; r= 0.870, P<0.01). IL-6 expression in urine was positively correlated with that in renal tissues (r=0.739, P<0.01)., Conclusions: IL-6 expression in the urine and renal tissues is increased in MCNS rats. IL-6 might play an important role in the pathogenesis of MCNS.

Objective: To investigate the status of visual disability and the demands for visual rehabilitation services in Beijing., Methods: Five hundred and fifty-five persons with visual disability in Beijing from the Second National Survey on Disability of China were involved in this study. Their visual disability and demands for rehabilitation were evaluated., Results: About three fourth of the visual disabled persons were over 60 years of age. Cataract, retinal and choroidal diseases, and glaucoma were the three leading causes of the visual impairment. Medical service was the number one (82.0%) demand for the persons with visual disability, although 89.4% of them had previously received some kinds of medial services. People who had received visual aid devices or rehabilitation training were 26.7% and 5.8%, respectively, while more people showed their demand for these service (36.6% and 11.9%, respectively). The demand for visual rehabilitation varied in different groups of age and severity of disability., Conclusion: Accessibility of high quality medical services for preventable blindness diseases should be further promoted. Public health education on visual rehabilitation is also needed.

Objective: To investigate the progression of visual field loss and to explore the prognosis of glaucomatous optic neuropathy in patients with chronic angle-closure glaucoma (CACG) after their intraocular pressures were well controlled under 21 mmHg., Methods: Forty-seven eyes of 29 patients in the Department of Ophthalmology in PUMC Hospital were included. All the patients had at least two separate tests of visual fields using the 24-2 program of the Humphery Visual Field Analyzer after their intraocular pressure were well controlled under 21 mmHg after sugery. The visual fields of patients were followed routinely for at least 1 year. In addition, all patients were divided into 2 groups according to follow-up period: 1-2 years group and over 2 years group. Visual field scores were calculated with the Advanced Glaucoma Intervention Study (AGIS) method. The visual fields were divided 5 sections and the sensitivity and defect depth of each section were calculated., Result: No statistically significant differences were found in terms of AGIS scores, localized sensitivities and localized defects within the time interval of the observation., Conclusion: Glaucomatous optic neuropathy is not likely to progressively deteriorate in CACG cases once their intraocular pressure are well controlled under 21 mmHg.