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γ-Aminobutyric acid (GABA) is a crucial neurotransmitter with wide application prospects. In this study, we focused on a GABA-producing strain from a traditional Chinese fermented beverage system. Among the six isolates, Lactobacillus hilgardii GZ2 exhibited the greatest ability to produce GABA in the traditional Chinese fermented beverage system. To increase GABA production, we optimized carbon sources, nitrogen sources, temperature, pH, and monosodium glutamate and glucose concentrations and conducted fed-batch fermentation. The best carbon and nitrogen sources for GABA production and cell growth were glucose, yeast extract and tryptone. Gradual increases in GABA were observed as the glucose and monosodium glutamate concentrations increased from 10 g/L to 50 g/L. During fed-batch fermentation, lactic acid was used to maintain the pH at 5.56, and after feeding with 0.03 g/mL glucose and 0.4 g/mL sodium glutamate for 72 h, the GABA yield reached 239 g/L. This novel high-GABA-producing strain holds great potential for the industrial production of GABA, as well as the development of health-promoting functional foods and medical fields. [ABSTRACT FROM AUTHOR]

Silkworm pupae are a major by-product of the silkworm mulberry industry, and the high content of tri-alpha-linolenin (glyceryl tri-alpha-linolenate, LnLnLn) in silkworm pupae oil makes it an excellent essential fatty acid supplement. However, the complex triglyceride composition of silkworm pupae oil limits its absorption and utilization by the human body. In this study, a sequential simulated moving bed (SSMB) approach for continuous separation was presented to recover the high-value tri-alpha-linolenin monomer from silkworm pupae oil. C18 particles were used as the stationary phase. Acetonitrile and isopropanol were used as the elution mobile phases. Under optimal SSMB conditions, the purity and yield of the extracted products were 95.15±2.06% and 2.14±0.06 mg/mL, respectively. In comparison to the conventional extraction approach, the yield of tri-alpha-linolenin separated by SSMB was 26.7 times greater, the dose of eluent was lowered by 2 times, and the eluent could be recycled. To validate the experimental parameters, a mass transfer diffusion model was used. The molecular diffusion coefficient of tri-alpha-linolenin was 2.61×10−6 cm2/s, the axial diffusion coefficient was 2.61×10−6+7.56×10−3μ, and the mass transfer diffusion coefficient was 0.87 s−1. The correlation coefficient between the model and the actual measured values was 0.9688. Consequently, the separation of tri-alpha-linolenin monomer in silkworm pupae oil by sequential simulated moving bed chromatography column can be reasonably described and predicted by this model. In conclusion, a novel approach to the commercialization of insect oils was developed by the extraction and purification of tri-alpha-linolenin from silkworm pupae oil using the SSMB approach. [ABSTRACT FROM AUTHOR]

β-Ga2O3 thin films with both a 45 nm Si-doped conductive epilayer and unintentionally doped epilayer were grown on c-plane sapphire substrate by metalorganic chemical vapor deposition. β-Ga2O3 based metal–oxide–semiconductor field-effect transistors (MOSFETs) were fabricated with gate recess depths of 20 nm and 40 nm (it indicated gate depth with 70 nm and 50 nm, respective), respectively, and without said recessing process. The conductivity of β-Ga2O3 epilayers was improved through low in situ doping using a tetraethoxysilane precursor to increase MOSFET forward current density. After recessing, MOSFET operation was transferred from depletion to enhanced mode. In this study, the maximum breakdown voltage of the recessed 40 nm transistor was 770 V. The etching depth of a recessed-gate device demonstrates its influence on device electrical performance. [ABSTRACT FROM AUTHOR]

In this work, we demonstrated Ga2O3-based power MOSFETs grown on c-plane sapphire substrates using in-situ TEOS doping for the first time. The β-Ga2O3:Si epitaxial layers were formed by the metalorganic chemical vapor deposition (MOCVD) with a TEOS as a dopant source. The depletion-mode Ga2O3 power MOSFETs are fabricated and characterized, showing the increase of the current, transconductance, and breakdown voltage at 150 °C. In addition, the sample with the TEOS flow rate of 20 sccm exhibited a breakdown voltage of more than 400 V at RT and 150 °C, indicating that the in-situ Si doping by TEOS in MOCVD is a promising method for Ga2O3 power MOSFETs. [ABSTRACT FROM AUTHOR]

In order to realize the optimal allocation of urban construction and geological environment resources, in this paper, the suitability evaluation index system is established, the comprehensive index method is used to evaluate, and the various evaluation factors are superimposed and analyzed. The results show that the area with good suitability accounts for 44.34%. The area with good suitability accounts for 33.86%. The area with medium suitability accounts for 19.27%, and the area with poor suitability accounts for about 2.49%. In this paper, the comprehensive environmental index method is used to evaluate the geological environment factors affecting the urban construction of Xi'an. The Xi'an urban construction geological environment suitability zoning is obtained. [ABSTRACT FROM AUTHOR]

In order to achieve the goal of mutual coordination between the urban construction and sustainable development of geological and ecological environment, the evaluation method and planning strategy for urban geological and ecological environment quality are proposed. In this study, taking the urban planning of Wansheng Economic Development Zone in Chongqing as an example, the status of geological and ecological environment quality from 2007 to 2019 is analyzed. Twenty evaluation indicators from the five aspects of land, hydrologic, resource, ecologic, and geological environment are selected to construct an evaluation system of urban geological and ecological environment quality. The evaluation indicator system of urban geological and ecological environment quality is established, the weights are determined with the analytic hierarchy process (AHP), and the grading standard of evaluation indicator is given. The urban geological and ecological environment quality is assessed in the way of fuzzy comprehensive evaluation, and the countermeasures for urban and rural planning are proposed. The results show that this system can improve the quality of geological and ecological environment in Wansheng Economic Development Zone in Chongqing; the geological and ecological environment quality of the eco-industrial functional zone 2 (F6) and the eco-industrial functional zone 3 (F7) has been maintained well, while the environment quality of other functional zones has shown a significant downward trend. Finally, the planning suggestions are adapting to the urban geological and ecological environment from three aspects of geological, ecological, and artificial environment. The research in this study provides a good guideline for the overall planning development of the city and rapid assessment of the ecological environment quality. [ABSTRACT FROM AUTHOR]

TiO2/g-C3N4 2D/2D heterojunction nanocomposites were successfully synthesized through a facile self-assembly method. The structure characterization results shows good interaction between TiO2 nanosheets and g-C3N4 nanosheets. The photocatalytic activity of TiO2/g-C3N4 samples were measured by hydrogen production in water splitting under visible light irradiation, which was found that the composites enhance the photocatalytic activity clearly compared to pure g-C3N4 and TiO2 nanosheets. The results could attribute to the formation of 2D heterojunction because of the stimulative charge transfer, promotional separation efficiency of photoexcited electron and hole and the suitable band positions. Besides, the samples exhibited substantial stability under visible light irradiation by the recycling experiments. The feasible photocatalytic mechanism was minutely discussed, which could explain the enhanced photocatalytic activity. [ABSTRACT FROM AUTHOR]

Multi-order radially polarized modes (RPMs), including Bessel-Gaussian, Gaussian, Super Gaussian, and multi-order hollow Gaussian are respectively utilized as the illumination laser to achieve tip-enhanced spectroscopy (TES). Based on the vector diffraction theory and finite difference time domain (FDTD) analysis, we achieve the optimization of RPM illuminated TES system, including the focal spot size, focal depth, and electric field enhancement factor, in which the focal spot size of 5th order hollow Gaussian RPM is smallest (0.54λ) and the focusing depth of super Gaussian RPM is longest (4.71λ). Specially, it is found that the multi-order hollow Gaussian RPM illuminated TES system with the tip cone angle of 45° reveals better focusing ability and 40~60-fold electric field enhancement factor compared to the linearly polarized mode (LPM) illuminated TES system. These results will supply a useful reference for spectral signal enhancement of TES system. [ABSTRACT FROM AUTHOR]

The plasticizer di(2-ethylhexyl) phthalate (DEHP) is ubiquitous in the environment and considered as carcinogen; however, the carcinogenic risk of human exposure to DEHP in the air via inhalation is lacking. A probabilistic incremental lifetime cancer risk (ILCR) model was implemented to quantitatively estimate the potential cancer risk of DEHP via human inhalation by using Monte Carlo simulation. We assessed the cancer risk in different age groups (children, adolescents, and adults) exposed to different DEHP concentrations (background low, indoor moderate, and occupational high) for different durations (2, 8, and 20 years). Results showed that the cancer risk of exposure to DEHP was below the acceptable limit (10) in the ambient air but was serious in indoor and occupational environments even at short exposure duration (2 years). The cancer risk of DEHP via inhalation in children was lower than that in adolescents and adults, but the risk in children via dermal and oral exposure to indoor dust and soft PVC toys should be considered. Sensitivity analysis indicated that the exposure concentration of DEHP was the strongest factor that influenced ILCR. Our work provides the evidence of cancer risk of DEHP via inhalation and highlights the risk in indoor and occupational environments. [ABSTRACT FROM AUTHOR]

Prevalence of allergic rhinitis has rapidly increased among Chinese children, but the reasons are unclear. Recent findings have suggested that exposure to outdoor air pollutants may increase the risk of allergic rhinitis, but the results were inconsistent. This study further investigated the effect of outdoor air pollutants on allergic rhinitis among preschool children. A standardized questionnaire on health, home and environmental factors was conducted for 4988 children aged 1–8 in the city of Changsha, and the concentrations of PM 10 (particle diameter ⩽10 μm), sulfur dioxide (SO 2) and nitrogen dioxide (NO 2) during 2006–2011 were acquired from the official web of Changsha Environmental Protection Agency. Results showed that the prevalence of children’s doctor diagnosed rhinitis was 8.4% (95% confidence interval [CI] 7.0%–10.0%). It was found that the prevalence of rhinitis was not associated with site-specific background concentrations of air pollutants, but significantly positively correlated with age-related accumulative personal exposure of PM 10, SO 2 and NO 2. We conclude that age-related accumulative personal exposure to ambient air pollution may play an important role in the development of rhinitis. [ABSTRACT FROM AUTHOR]

Asthma, rhinitis and eczema (allergic or non-allergic) have increased throughout the world during the last decades, especially among children. Changes in the indoor environment are suspected to be important causes. China has experienced a dramatic change in indoor environmental exposures during the past two decades. However, such changes and their associations with children’s asthma and other health aspects have not been thoroughly studied. China, Children, Homes, Health (CCHH), Phase I, was a cross-sectional questionnaire survey of 48219 children 1–8 years old in 10 Chinese cities during 2010–2012. The questionnaire includes the International Study of Asthma and Allergies in Childhood (ISAAC) core health questions and additional questions regarding housing, life habits and outdoor environment. In health analyses, children aged 3–6 years old were included. The prevalences of doctor diagnosed asthma varied from 1.7% to 9.8% (mean 6.8%), a large increase from 0.91% in 1999 and 1.50% in 2000. The prevalence of wheeze, rhinitis and atopic eczema (last 12 months) varied from 13.9% to 23.7%, 24.0% to 50.8% and 4.8% to 15.8%, respectively. Taiyuan had the lowest prevalences of all illnesses and Shanghai the highest, except for wheezewhere the highest value was for Urumqi. We found (1) no obvious association between disease prevalences and ambient PM 10 concentrations and (2) higher prevalences of disease in humid climates with hot summers and cold winters, but with no centrally heated buildings. Associations between the diseases and economic status as indexed by Gross Domestic Product (GDP) requires further study. [ABSTRACT FROM AUTHOR]

The temporal variation of ventilation coefficient was estimated and a simple model for the prediction of urban ventilation coefficient in Changsha was developed. Firstly, Pearson correlation analysis was used to investigate the relationship between meteorological parameters and mixing layer height during 2005-2009 in Changsha, China. Secondly, the multi-linear regression model between daytime and nighttime was adopted to predict the temporal ventilation coefficient. Thirdly, the validation of the model between the predicted and observed ventilation coefficient in 2010 was conducted. The results showed that ventilation coefficient significantly varied and remained high during daytime, while it stayed relatively constant and low during nighttime. In addition, the diurnal ventilation coefficient was distinctly negatively correlated with PM (particle with the diameter less than 10 μm) concentration in Changsha, China. The predicted ventilation coefficient agreed well with the observed values based on the multi-linear regression models during daytime and nighttime. The urban temporal ventilation coefficient could be accurately predicted by some simple meteorological parameters during daytime and nighttime. The ventilation coefficient played an important role in the PM concentration level. [ABSTRACT FROM AUTHOR]

Source apportionment of particulate matters with aerodynamic diameter less than 10 μm (PM10) was conducted in the suburban area of Changsha, China. PM10 samples for 24 h collected with TEOM 1400a and ACCU system in July and October 2008 were chemically analyzed by the wavelength dispersive X-ray fluorescence (WD-XRF). Source appointment was implemented by the principal component analysis/absolute principal component analysis (PCA/APCA) to identify the possible sources and to quantify the contributions of the sources to PM10. Results show that as the PM10 concentration is increased from (85.6±43.7) μg/m3 in July 2008 to (107.6±35.7) μg/m3 in October 2008, the concentrations of the anthropogenic elements (P, S, Cl, K, Mn, Ni, Cu, Zn, and Pb) are basically increased but concentrations of the natural elements (Na, Mg, Al, Si, Ca, Ti, and Fe) are essentially decreased. Six main sources of PM10 are identified in the suburban of Changsha, China: soil dust, secondary aerosols, domestic oil combustion, waste incineration, traffic emission, and industrial emission contribute 57.7%, 24.0%, 9.8%, 5.0%, 2.0%, and 1.5%, respectively. Soil dust and secondary aerosols are the two major sources of particulate air pollution in suburban area of Changsha, China, so effective measures should be taken to control these two particulate pollutants. [ABSTRACT FROM AUTHOR]