Visual impairment and spectacle coverage rate in Baoshan district, China: population-based study

BACKGROUND: To investigate the prevalence and risk factors of visual impairment associated with refractive error and the unmet need for spectacles in a special suburban senior population in Baoshan District of Shanghai, one of several rural areas undergoing a transition from rural to urban area, where data of visual impairment are limited. METHODS: The study was a population based survey of 4545 Chinese aged (age: >60 years or older ) at Baoshan, Shanghai, in 2009. One copy of questionnaire was completed for each subject. Examinations included a standardized refraction and measurement of presenting and best corrected visual acuity (BCVA) as well as tonometry, slit lamp biomicroscopy, and fundus photography. RESULTS: The prevalence of mild (6/12 to 6/18), moderate (6/18 to 6/60) and severe visual impairment was 12.59%, 8.38% and 0.44%, respectively, and 5.26%, 3.06% and 0.09% with refractive correction. Visual impairment was associated with age, gender, education and career, but not insurance . The prevalence of correctable visual impairment was 5.81% (using 6/18 cutoff) and 13.18% (using 6/12 cutoff). Senior people and women were significantly at a higher risk of correctable visual impairment, while the well-educated on the contrary. The prevalence of undercorrected refractive error (improves by 2 or more lines with refraction) was 24.84%, and the proportion with undercorrected refractive error for mild, moderate , severe and no visual impairment was 61.54%, 67.98%, 60.00% and 14.10%, respectively. The spectacle coverage rate was 44.12%. Greater unmet need for spectacles was observed among elderly people, females, non-peasant, and subjects with less education and astigmatism only. CONCLUSIONS: High prevalence of visual impairment, visual impairment alleviated by refractive correction, and low spectacle coverage existed among the senior population in Baoshan District of Shanghai. Education for the public of the importance of regular examination and appropriate and accessible refraction service might be helpful to solve the problem

Analysis on life quality of children with high myopia

Objective·To explore the association between high myopia and life quality among children.Methods·Cross-sectional study method was adopted in this study. Highly myopic children aged 4‒10 from 16 districts in Shanghai were enrolled through Shanghai Child and Adolescent Large-scale Eye Study-High Myopia Registration Study. Baseline data for spherical equivalent after cycloplegia and questionnaire data in 2020 were collected. Emmetropic children aged 4‒10 from 16 kindergartens and elementary schools in Jing'an District and Pudong New Area were enrolled. The uncorrected visual acuity, corrected visual acuity and spherical equivalent without cycloplegia were measured through myopia screening in schools, and the questionnaire on quality of life was filled out. Quality of life was measured by the Strengths and Difficulties Questionnaire (SDQ) and EuroQol Five Dimensions Questionnaire Visual Analogue Scale (EQ-VAS). After describing and testing the differences in variable distributions between the highly myopic children group and the emmetropic children group, the differences in life quality between the two groups, and the association between spherical equivalent and life quality scores of the highly myopic children were examined by a linear regression model.Results·A total of 193 children with high myopia and 209 children with emmetropia were enrolled. There were statistically significant differences in age [(9.58±0.94) years vs (7.63±1.50) years, P<0.001] and gender distribution (46.6% males vs 62.7% males, P=0.001) between the highly myopic children and emmetropic children. After adjusting for age and gender, it was found that there was no statistically significant difference in SDQ score between the highly myopic children and emmetropic children (β=0.313, 95%CI -0.723‒1.349, P=0.553), but the EQ-VAS score in the highly myopic children was lower than that in the emmetropic children (β=-3.805, 95%CI -6.593‒ -1.017, P=0.008). There was no significant relationship between spherical equivalent and SDQ score (β=0.297, 95%CI -0.035‒0.628, P=0.079) and EQ-VAS score (β=0.579, 95%CI -0.330‒1.489, P=0.211) in the highly myopic children.Conclusion·In children with high myopia, self-evaluated overall health status reflected by EQ-VAS score is poorer compared with that in children with emmetropia. However, the EQ-VAS score is not associated with the degree of high myopia

Beyond the snapshot: identification of the timeless, enduring indicator microbiome informing soil fertility and crop production in alkaline soils

Background Microorganisms are known to be important drivers of biogeochemical cycling in soil and hence could act as a proxy informing on soil conditions in ecosystems. Identifying microbiomes indicative for soil fertility and crop production is important for the development of the next generation of sustainable agriculture. Earlier researches based on one-time sampling have revealed various indicator microbiomes for distinct agroecosystems and agricultural practices as well as their importance in supporting sustainable productivity. However, these microbiomes were based on a mere snapshot of a dynamic microbial community which is subject to significant changes over time. Currently true indicator microbiomes based on long-term, multi-annual monitoring are not available. Results Here, using samples from a continuous 20-year field study encompassing seven fertilization strategies, we identified the indicator microbiomes ecophysiologically informing on soil fertility and crop production in the main agricultural production base in China. Among a total of 29,184 phylotypes in 588 samples, we retrieved a streamlined consortium including 2% of phylotypes that were ubiquitously present in alkaline soils while contributing up to half of the whole community; many of them were associated with carbon and nutrient cycling. Furthermore, these phylotypes formed two opposite microbiomes. One indicator microbiome dominated by Bacillus asahii, characterized by specific functional traits related to organic matter decomposition, was mainly observed in organic farming and closely associated with higher soil fertility and crop production. The counter microbiome, characterized by known nitrifiers (e.g., Nitrosospira multiformis) as well as plant pathogens (e.g., Bacillus anthracis) was observed in nutrient-deficit chemical fertilizations. Both microbiomes are expected to be valuable indictors in informing crop yield and soil fertility, regulated by agricultural management. Conclusions Our findings based on this more than 2-decade long field study demonstrate the exciting potential of employing microorganisms and maximizing their functions in future agroecosystems. Our results report a “most-wanted” or “most-unwanted” list of microbial phylotypes that are ready candidates to guide the development of sustainable agriculture in alkaline soils

VIBRATION PERFORMANCE ENGINEERING OPTIMIZATION FOR INTERNAL COMBUSTION FORKLIFT TRUCK STEERING SYSTEM BASED ON UNIFORM DESIGN

The modal analysis of steering system was made because of the excessive vibration of a certain forklift truck when the engine at medium and low speed conditions at first in this paper. The vibration optimum design was put forward to reduce the vibration of steering wheel by the method of Uniform Design. the test results show that the stiffness of improved steering system is increased and the vibration is decreased obviously on the basis of the invariability of costs,especially when the engine at low speed,the acceleration of vibration on direction x,y,z are reduced 83. 8%,90. 3%,83. 7% respectively. The optimum method provides references for the optimum design of body and frame type structures

Fractal Description Of Pore Structures Of Low Permeability Oil Reservoirs And Its Relationship With Gemini Surfactant Flooding

Gemini surfactant flooding is a promising technique to enhance oil recovery from medium-high permeability oil reservoirs. The screening of the gemini surfactants are mainly based on their capability of lowering the surface tension between oil and water. However, gemini surfactants with high capability of lowering the surface tension do not necessarily enhance oil recovery from low permeability oil reservoirs. Based on fractal method and the mercury injection curve data, the fractal dimensions of the pore structures of low permeability oil reservoirs are different from those of medium-high permeability oil reservoirs. Based on the fractal dimensions of molecular fragments, the fractal dimensions of gemini surfactants are in relation to the fractal dimensions of the pore structures of low permeability oil reservoirs. Based on the fractal dimensions of the pore structures of low permeability oil reservoir Z and molecular fragments, gemini surfactant D is designed and applied in developing the reservoir. Gemini surfactant D enhanced oil recovery 5% more than conventional gemini surfactants. The fractal dimensions of the pore structures of medium-high permeability oil reservoirs range from 2 to 3. The fractal dimensions of the pore structures of low permeability oil reservoir Z are less than 2. The fractal dimension of the spacer group should match with fractal dimensions of the pore structures. The gemini surfactants are absorbed more onto the rock surface as the spacer groups of the gemini surfactants are less complicated than the rock surface. Fractal dimension is supplementary to the parameters (permeability and porosity) that are used to estimate low permeability oil reservoirs. Low permeability oil reservoirs which were not able to be developed are able to be developed. This helps more and more low quality reserves be turned into producing reserves. Copyright 2010, Society of Petroleum Engineers.EI

Microscopic production characteristics of tight oil in the nanopores of different CO2-affected areas from molecular dynamics simulations

Understanding the mechanisms of CO2 extraction or flooding are vital for enhancing oil recovery (EOR) in tight reservoirs. In this study, the CO2 EOR mechanism in the displacement-affected area (DPAA) and diffusionaffected area (DFAA) of quartz nanopores were thoroughly investigated using molecular dynamics simulation techniques. First, the following two contents were mainly simulated, namely CO2 flooding oil in the single/ double nanopores of DPAA and CO2 extraction oil in dead-end nanopores of the DFAA with and without the water film. Then, tight oil potential energy, threshold capillary pressure, CO2 solubility, and oil swelling in nanopores were calculated to clarify the effects of CO2 on oil transport. Moreover, different CO2 injection/ flowback rates and different water film thicknesses on dead-end nanopores on oil recovery were discussed. In the DPAA, the CO2 solubility and the oil swelling factor gradually decreased with distance from the CO2-oil interface (Y = 0 nm), where the higher the injection rate, the more easily the CO2 dissolved in the oil. However, the injection rate of CO2 was inversely proportional to oil recovery. In addition, it took longer for the displacement efficiency in the 6 nm pore of double pores to reach the same displacement efficiency as in the single 6 nm pore. In the DFAA, the effect of flowback rate on the displacement efficiency of oil was relatively low. However, the thickness of the water film was a key factor that affected the oil displacement efficiency in the DFAA

Microscopic production characteristics of tight oil in the nanopores of different CO2-affected areas from molecular dynamics simulations

Understanding the mechanisms of CO2 extraction or flooding are vital for enhancing oil recovery (EOR) in tight reservoirs. In this study, the CO2 EOR mechanism in the displacement-affected area (DPAA) and diffusionaffected area (DFAA) of quartz nanopores were thoroughly investigated using molecular dynamics simulation techniques. First, the following two contents were mainly simulated, namely CO2 flooding oil in the single/ double nanopores of DPAA and CO2 extraction oil in dead-end nanopores of the DFAA with and without the water film. Then, tight oil potential energy, threshold capillary pressure, CO2 solubility, and oil swelling in nanopores were calculated to clarify the effects of CO2 on oil transport. Moreover, different CO2 injection/ flowback rates and different water film thicknesses on dead-end nanopores on oil recovery were discussed. In the DPAA, the CO2 solubility and the oil swelling factor gradually decreased with distance from the CO2-oil interface (Y = 0 nm), where the higher the injection rate, the more easily the CO2 dissolved in the oil. However, the injection rate of CO2 was inversely proportional to oil recovery. In addition, it took longer for the displacement efficiency in the 6 nm pore of double pores to reach the same displacement efficiency as in the single 6 nm pore. In the DFAA, the effect of flowback rate on the displacement efficiency of oil was relatively low. However, the thickness of the water film was a key factor that affected the oil displacement efficiency in the DFAA

Characteristics of micro scale nonlinear filtration

Take the flow characteristics of fluid in micro tube as the object, the characteristics of nonlinear filtration in low permeability reservoirs were studied using micro scale method by simulating the micro pore throat of reservoir with the micro tube which has the similar scale pore throat of low permeability reservoirs. The flow characteristics of de-ionized water flowing through fused silica capillary tubes with radius of 10.0 μm, 7.5 μm, 5.0 μm and 2.5 μm were investigated in experiments. Relationship between average flow rate and pressure gradient, effect of pressure gradient on fluid boundary layer, and relationships between flow resistance coefficient and Reynolds number were analyzed respectively in these experiments with different micro tubes. The flow of fluid through micro tubes with low velocity has nonlinearity, and the extent of nonlinearity increases with the tube radius decreasing. Nonlinear flow experimental points can be matched by quadratic curve. In micro flow, the percentage of effective fluid boundary layer thickness to micro tube radius decreases with the pressure gradient increasing. Research results indicated that Reynolds number can be used as the criteria of nonlinear flow. Flows with Reynolds number less than 10−3 have nonlinear features. Key words: low permeability reservoir, micro scale, nonlinear flow, boundary fluid laye