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Objective To analyze the types, origins, fluoride content of brick tea available in the Sanjiangyuan region, and the local residents' consumption of milk tea, providing a scientific basis for assessing the safety of fluoride intake from brick tea. Methods In 2022, based on historical data, a survey was conducted in 11 counties (cities) in the Sanjiangyuan region where residents habitually consume milk tea. Villages with a brick tea consumption habit were selected as the unit of investigation within each county. Ten households were randomly sampled from each village to collect demographic data and information on milk tea consumption. Samples of drinking water, brick tea, and milk tea were collected to measure fluoride content, calculating the daily per capita fluoride intake from milk tea for individuals over 16 years of age. The fluoride content in water and tea was measured using ion-selective electrode methods. Results A total of 82 drinking water samples were collected, with an average fluoride concentration of 0.22 mg/L, ranging from 0.10 to 0.74 mg/L. A total of 873 brick tea samples were collected, primarily consisting of Kang brick and Fu brick, accounting for 42.96% (375/873) and 34.48% (301/873) of the total, respectively. Other varieties included Jin Jian (11.80%, 103/873), Da tea (4.81%, 42/873), Hei brick (4.35%, 38/873), and Qing brick (1.60%, 14/873). There were 69 brands of brick tea available, predominantly produced in Sichuan Province (56.24%, 491/873), followed by Hunan Province (37.46%, 327/873). The average fluoride content in brick tea was 752.3 mg/kg, with a range of 242 to 1 836 mg/kg, with Jin Jian and Kang brick showing significantly higher fluoride levels (P < 0.001). Only three samples of brick tea had fluoride content ≤300 mg/kg, representing 0.34% of all samples. The annual per capita consumption of brick tea for individuals over 16 years was 3.40 kg (1.05-5.37 kg). A total of 554 milk tea samples were collected, with an average fluoride concentration of 2.25 mg/L, ranging from 0.82 to 12.18 mg/L. The daily per capita consumption of milk tea was 2 575 ml, leading to a daily per capita fluoride intake from milk tea of 5.79 mg, with a range of 2.92 to 13.06 mg. In ten counties, the daily per capita fluoride intake from milk tea exceeded the national health standard for total daily fluoride intake (3.50 mg). Conclusion The brick tea circulating in the Sanjiangyuan region is mainly composed of Kang and Fu bricks produced in Sichuan and Hunan, with excessive fluoride content in both brick tea and milk tea. The fluoride intake among the population exceeds safe levels, posing widespread health risks, necessitating the prompt implementation of effective preventive measures. [ABSTRACT FROM AUTHOR]

Copyright of Industrial Water Treatment is the property of CNOOC Tianjin Chemical Research & Design Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The semiconductor industry wastewater is complex due to it contains large amount of pollutants such as heavy metals, toxic cyanide, fluoride, nitrogen, and phosphorus, etc. Meanwhile, the poor biodegradability and low C/N makes it difficult to directly use biological methods for treatment. The sewage treatment plant in a certain high-tech industrial park adopts the treatment process of “grille+aeration sedimentation tank+high-efficiency sedimentation tank+advanced A2/O+MBR+disinfection tank”. The changes of influent and effluent water quality during the actual operation for 5 months were explored. The results showed that the treatment process had a good removal effect on pollutants. During operation, pollutants such as suspended solids, COD, NH4+-N, TN, TP, and fluoride in effluent were maintained below 4, 26, 1, 8, 0.1, and 1.5 mg/L, respectively, which always met the first level class A standards of Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB 18918-2002). In addition, the electricity cost of water treatment was about 0.536 yuan/m3, the chemicals cost was about 0.220 yuan/m3, and the direct operating cost was about 0.756 yuan/m3.

BackgroundHebei Province is located in the North China Plain. In view of the influence of geological background and the acute and chronic hazards caused by excessive drinking water toxicological indicators, coupled with the large coverage of water supply in urban areas and the existence of self-built water supply facilities, it is necessary to understand the drinking water sanitation status in urban areas and conduct health risk assessment. ObjectiveTo investigate main indicators affecting the compliance rate of drinking water quality in urban areas of Hebei and evaluate the chronic non-carcinogenic risks of 11 chemicals. MethodsThe collection, preservation, and testing of 14299 samples of finished water, tap water, and secondary water supply in urban areas of Hebei Province from 2017 to 2021 were conducted following the Standard examination methods for drinking water (GB/T 5750—2006). A total of 11 chemicals were evaluated according to the Hygienic standards for drinking water (GB 5749—2006). The chronic non-carcinogenic risks of the 11 chemicals in drinking water by oral exposure were assessed using the four-step health risk assessment model developed by the United States Environmental Protection Agency and the Technical guide for environmental health risk assessment of chemical substances (WS/T 777—2021). ResultsFrom 2017 to 2021, the compliance rates of arsenic, cadmium, hexavalent chromium, lead, mercury, selenium, cyanide, chloroform, and carbon tetrachloride in drinking water in urban areas of Hebei Province were all 100.00%, and fluoride and nitrate (N) were the main indicators affecting water quality compliance, with compliance rates of 97.68% and 99.53% respectively. The compliance rate of fluoride increased year by year (χ2=178.06, P

BACKGROUND: With the improvement of diet and living standards, acidic diet and orthodontic treatment have become the main causes of enamel surface demineralization. As the first step of dental caries, enamel demineralization should be actively intervened. Mechanical grinding has great damage and does not conform to the concept of minimally invasive medicine. Biomimetic remineralization is the best way to deal with enamel demineralization at present. OBJECTIVE: To summarize the mechanism, application and research progress of biomimetic remineralization of early enamel demineralization, and provide ideas for further overcoming the hot issues of biomimetic remineralization. METHODS: English keywords "enamel demineralization, biomimetic remineralization, amelogenin, amorphous calcium phosphate" were used to search PubMed. Chinese keywords "enamel demineralization, biomimetic remineralization, amelogenin" were used to search CNKI. Through screening, 72 articles were finally obtained for review. RESULTS AND CONCLUSION: (1) At present, there are drug treatments for enamel demineralization, such as fluoride preparations, laser treatment, resin penetration, remineralization treatment and other treatment methods. Biomimetic remineralization is the most ideal repair method for early enamel demineralization. (2) In the narrow sense, enamel remineralization refers to the mineral re-deposition inside the enamel after early enamel demineralization. In the broad sense, enamel remineralization includes the mineralization deposition on the surface and inside of enamel. (3) Clinical biomimetic remineralization reagents are mainly composed of amelogenin, non amelogenin, amelogenin peptide, casein phosphopeptide-amorphous calcium phosphate complex, etc. The advantages of protein and peptide materials are that they conform to the physiological mechanism and can generate high-strength remineralized materials by inducing orientation. The disadvantages are that the manufacturing process is relatively complex and the cost is high. The remineralization effect of amorphous calcium phosphate complex is good, but it needs to be combined with other materials to play a role. Other calcium phosphate materials are easy to carry and beautiful, but they are easy to cause the formation of dental calculus. (4) Future research should focus on the following aspects: increasing experimental data and clinical results, and clarifying the indications of various methods; explore more biomimetic remineralization methods and find suitable alternative materials; find a reasonable way to combine materials, so that their advantages and disadvantages complement each other. The portability of clinical application can be strengthened to increase the frequency of daily use, so that short-term experimental conclusions can be supported by long-term clinical data. [ABSTRACT FROM AUTHOR]

Copyright of Inorganic Chemicals Industry is the property of Editorial Office of Inorganic Chemicals Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Hongjiang—Qianshan fault has abundant medium-low temperature geothermal resources. However, the excessive fluorine concentration in geothermal groundwater restricts the development and utilization of geothermal resources. 20 samples were collected in this region for identifying the genetic mechanism of medium-low temperature of fluoride-enriched geothermal resources. The hydrochemical results indicate that the hydrochemical characteristic of high fluoride geothermal groundwater is HCO3-Na. The groundwater environment is alkaline and weakly alkaline. The fluoride concentration in geothermal groundwater is 2−12 times greater than the upper limited value, while those in the surface water and shallow groundwater are within the permittable threshold range. The isotopic results reveal that the recharge elevations and circulation depth are 797−2186m and 893−1893m, respectively. Quartz provides the most reliable estimations of reservoir temperatures, ranging from 79.4℃ to 113.1℃. The fluoride in geothermal groundwater originates from the rock weathering and mineral dissolution. Cation exchange and alkaline condition are the main influence factors for fluorine enrichment. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Inorganic Analytical Chemistry / Zhongguo Wuji Fenxi Huaxue is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

White light emitting diodes have great advantages over traditional light sources owe to their energy-saving, environmental protection, high efficiency, and so on, which have a wide range of applications in indoor lighting, outdoor lighting, automotive lamps and electronic backlighting devices. It is always the unremitting pursuit of researchers in this field to obtain warm white light emitting diodes with low correlated color temperature (CCT=2 700-4 500 K), high color rendering index (CRI, Ra>80), cost saving and suitable for human eyes. Red phosphor can effectively improve the shortcomings and enhance the luminescent performance of such devices, which plays an important role in high color rendering phosphor-converted white light emitting diodes. Therefore, its research and development is of great significance. In this paper, the research progress of Mn4+-doped fluoride red phosphor in recent years was reviewed, and the conventional and green preparation methods of this phosphor were introduced. In terms of the poor moisture stability of Mn4+-doped fluoride red phosphor, relevant studies on improving its moisture-resistance property were summarized. Prospectively, this review concludes with a brief view of potential challenges and future development directions of high-performance Mn4+ doped fluoride phosphor. [ABSTRACT FROM AUTHOR]

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BackgroundThe burden of chronic kidney diseases (CKD) is continuously increasing in the globe. Environmental factors are one of the trigger factors for chronic kidney diseases of unknown etiology (CKDu). However, the current toxicological evidence on the renal effects induced by environmental high concentrations of multiple ions in drinking water and high temperature exposure is very limited. ObjectiveTo preliminary investigate the renal effects of exposure to drinking water with environmental high concentrations of fluoride, calcium, sodium, and bromide ions alone or in combination with high temperature in mice. MethodsA mouse drinking water exposure model was established using ICR male mouse (8 weeks old) with exposure to 3 mg·L−1 fluoride ions, 250 mg·L−1 calcium ions, 400 mg·L−1 sodium ions, and 1 mg·L−1 bromide ions (to mimic the high concentration of ions in the groundwater in the areas with a high prevalence rate of CKDu in Sri Lanka) and high temperature of 32 ℃. ICR male mice were randomly divided into a mixed fluoride-calcium-sodium-bromide ion and high temperature exposure group, exposure groups of each ion and high temperature alone, a fluoride-calcium-sodium ion exposure group, and a fluoride-calcium-sodium-bromide ion exposure group. In the control group, the animals were given normal purified water at room temperature of (23±2) ℃. After 12 consecutive weeks of exposure, body weights and liver (kidney) organ coefficients were determined. Assessment of renal histopathologic damage was performed by hematoxylin-eosin staining and pathology scoring. At the end of the 12-week exposure period, 24 h urine samples were collected for the measurements of creatinine (UCr), albumin (ALB), neutrophil gelatinase-associated lipocalin (NGAL), and β2-microglobulin (β2-MG) levels. Cell apoptosis was assessed by TUNEL assay. ResultsThe mice in the mixed exposure group showed a significant decrease in body weight and marked increases in the scores of renal histopathological injuries and the urinary levels of β2-MG compared to those of the control mice (P0.05), but the renal histopathological injury scores were significantly increased (P0.05). Furthermore, the renal histopathological injury score showed no significant differences between the fluoride-calcium-sodium ion exposure group and the fluoride-calcium-sodium-bromide ion exposure group (P>0.05). The interaction between bromide ions and fluoride-calcium-sodium ions on renal tissue pathological damage was not statistically significant (P>0.05). Results from the TUNEL assay showed a significant increase in renal cell apoptosis in the fluoride-calcium-sodium ion exposure group (P

Arsenic (As) and fluoride (F) are two typical harmful elements with high concentrations in Yangbajing high-temperature geothermal water, and the release of As and F from geothermal sources to the surface or near-surface environment can be further promoted and accelerated through geothermal development, causing surface water and soil environmental pollution. To understand the enrichment mechanism of As and F in the geothermal water body, hydrochemical characteristics as well as the concentrations of As and F were investigated by water quality analyzer, atomic fluorescence spectrometry, X-ray fluorescence spectrometry, and ion selective electrode method. The results indicate that the main sources of As and F in geothermal water and surface soil are water-rock leaching interaction. Unique hydrochemical characteristics (Na-HCO3 ∙Cl) with high concentration Na+ (reach to 445.5mg/L), poor in Ca2+ (as low as 3.31mg/L), and high pH (7.87−9.42) provided a favourable condition for the leaching of As and F in water. Affected by water vapor evaporation, the concentrations of As and F in hot spring water were higher than those in geothermal water and reached 6.50mg/L and 17.89mg/L, respectively. Notably, the total concentrations of As and F in waters were significantly higher than the maximum allowable emission concentrations for harmful components (0.5mg/L for As, and 10mg/L for F) in the Geothermal Resources Assessment Method (DZ40—85). Moreover, the concentrations of total As and F in the soils were 79.50−99.08mg/kg and 1162.70−1285.10mg/kg, respectively, significantly higher than the background values in Xizang soil. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Asian Journals of Ecotoxicology is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The high incidence and untreated rate of root caries, a common and frequently occurring oral disease with challenging treatment in elderly individuals, is the main cause of tooth loss among elderly people, as rapid development results in pulpitis and periapical periodontitis or residual crown and root, which has been regarded as one of the common chronic oral diseases seriously affecting the quality of life of elderly people. Thus, early intervention and prevention are important. Traditional dental materials for preventing root caries have been widely used in clinical practice; however, they have the disadvantages of tooth coloring, remineralization and low sterilization efficiency. A series of new dental materials for preventing root caries have gradually become a research hotspot recently, which have the advantages of promoting the mineralization of deep dental tissue, prolonging the action time and enhancing adhesion. Future caries prevention materials should be designed according to the characteristics of root surface caries and the application population and should be developed toward simplicity, high efficiency and low toxicity. This review describes current research regarding anti-caries prevention material application, serving as a theoretical underpinning for the research of root caries prevention materials, which is important for both promotion in the effective prevention of root caries and improvement in the status of oral health and the quality of life among old people.

Copyright of Journal of Prevention & Treatment For Stomatological Diseases is the property of Journal of Prevention & Treatment For Stomatological Diseases Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Surfactant Detergent & Cosmetics (2097-2806) is the property of China Surfactant Detergent & Cosmetics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Tea Science is the property of Journal of Tea Science Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Explosives & Propellants is the property of Chinese Journal of Explosives & Propellants Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Treatment and resource utilization of mine drainage is an effective way to protect the ecological environment and address the issue of water shortage in mining areas. According to the characteristics of mine drainage of large water flow, high suspended solid, high salinity and containing fluoride, the purification process of two-stage preprecipitation and clarification was adopted in Zhengtong coal mine, and the mechanical clarification unit was optimized to synergistically remove suspended solid and fluoride. The operation result showed that the average SS removal rates of radial flow sedimentation tank, horizontal flow sedimentation tank and mechanical accelerated clarifier were 72. 5%, 48. 3% and 98.1%, respectively, under the conditions of the average concentration of influent SS was 3342 mg·L^-1 and the dosages of PAC 80 mg·L^-1 and PAM 0.8 mg·L^-1. The influent and effluent concentrations of fluoride were 1.20 mg·L^-1 and 0.93 mg·L^-1, respectively. The fluoride removal rate achieved 31.0%. The effluent quality indexes were better than the design criteria. The operation cost of mine drainage treatment was 0.34 yuan·ton^-1.

Shendong mining area is located in the north of Shaanxi Province and the south of Ordos City, Inner Mongolia, with dry climate, sparse precipitation and water resources scarcity. A large amount of mine water produced in the process of coal mining is an important source of production and living water. However, the concentrations of fluoride in mine water in different regions of Shendong mining areas present significant differences, while the concentration is relatively high in some areas. Therefore, the distribution characteristics and genesis of high fluoride mine water was analyzed in this study, which was of great significance for the resource reuse of mine water. Based on the analysis results of 58 groups of mine water quality at different regions in the Shendong mining area, research methods such as mathematical statistics, piper three-line diagram, gibbs diagram, SI simulation, etc. were used. Meanwhile, XRF analysis was conducted on rock cores and coal seam roof rocks collected from different areas to explore the spatiotemporal distribution characteristics and formation mechanism of fluorine in mine water at different burial depths in the northeastern and central mining areas. The results showed that the concentration of F- in mine water varied from 0.3 to 13.7 mg/L, with an average value of 4.3 mg/L. The pH value of mine water with higher F- concentration was alkaline. In the horizontal direction, the F- concentration in mine water was higher in the north and southwest of Shendong mining area, while it presented lower in the southeast. The fluorine concentration presented an increasing tendency with the enhancement of mining depth in the vertical direction. The F- concentration of mine water replenished by groundwater in different depths of Yan'an Formation aquifer varied greatly. The lower F- concentration was observed in the Yan'an Formation aquifer with a depth of 80-130 meters , whereas the relatively higher value was shown at the 200-500 meters depth. The trend of fluorine concentration in mine water is not obvious with the changes in the season The XRF analysis of fluorinated minerals in rock samples from the Yan'an Group indicated that the contents of fluorinated minerals in the northern and western central mining areas were relatively higher compared with that in the eastern central mining area. The high F- concentration in mine water had a certain relationship with the hydro-chemical environment. Evaporation and concentration process, cation alternately adsorption, and mineral dissolution caused by water-rock interaction led to the enrichment of F- in groundwater.

Using the wetland of Qiangwei Lake in Lianyungang City, Jiangsu Province as the study area, the fluoride content of common aquatic plants and aquatic animals was examined against the background of water fluoride concentration of about 1. 0 mg / L. The results showed that the fluoride content of common aquatic plants ranged from 121. 92 to 2 684. 18 mg / kg, and the submerged plant bitter grass showed a high fluoride enrichment ability, and the fluoride content reached 2 479. 60 mg / kg in its body. The order of fluoride content in aquatic plants from high to low was Vallisneria spinulosa > Myriophyllum verticillatum > Potamogeton malaianus > Typha angustifolia > Ceratophyllum demersum > Trapa bispinosa > Phragmites communis > Najas marina = Hydrocharis dubia > Hydrilla verticillata > Potamogeton pectinatus. For aquatic animals, macrobenthos named Macrobrachium nipponense exhibited high fluoride bioaccumulation ability, with an average fluoride content of 2 757. 62 mg / kg, while the fluoride content in Cipangopaludina chinensis was relatively low. Under the conditions of different influent fluoride concentrations, there was no significant difference in the fluoride concentration of the inlet and outlet water bodies after flowing through each functional area of the wetland, which meaned that the surface wetland had no obvious purification and removal effect on fluoride in the water body. [ABSTRACT FROM AUTHOR]

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Copyright of Storage & Process is the property of Tianjin Academy of Agricultural Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Arid Zone Research / Ganhanqu Yanjiu is the property of Arid Zone Research Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to solve the serious problems of F−、Fe2+ and Mn2+ in underground water of mining area, the serpentine loaded hydroxy-apatite (Srp/HAP) composite adsorbent was prepared by wet chemical coprecipitation method, and the simultaneous removal of fluorine, iron and manganese in underground water was studied. Through batch experiment and CCD response optimization experiment, the effects of dosage, reaction time and pH on the removal efficiency of F−、Fe2+ and Mn2+ were investigated, and a quadratic regression model with the removal rates of F−、Fe2+ and Mn2+ as response values was established. Srp/HAP adsorption and regeneration experiments were carried out to explore its reusability. The results show that the optimal reaction conditions of Srp/HAP treatment of complex water samples with mass concentrations of F−、Fe2+ and Mn2+ of 5 mg/L, 20 mg/L and 5 mg/L respectively are as follows: When 3.64 g/L water sample was added, the reaction time was 120.47 min and the pH value was 6.3, the corresponding removal rates of F−、Fe2+ and Mn2+ were 98.23%, 99.9% and 99.7% respectively. The effluent shall meet the requirements of the 《Standards for drinking water quality》(GB5749—2006).The adsorption process of F−、Fe2+ and Mn2+ by Srp/HAP was well fitted by the CCD optimized experimental model. The absolute error between the predicted value and the experimental value is less than 5%, which proves that the experimental model is reliable. After five times of regeneration, the removal rates of F−、Fe2+ and Mn2+ by Srp/HAP composite particles decreased by 16.13%, 10.5% and 15.4%, respectively, less than 20%. Srp/HAP composite particles can be used as an excellent adsorbent for the treatment of groundwater containing fluoride, iron and manganese ions.

Copyright of Asian Journals of Ecotoxicology is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

ObjectiveTo evaluate the intake level of fluoride and potential health risks for herdsmen in Qinghai province.MethodsThe monitoring data of fluoride content in brick tea from 2019 to 2021 and the data of brick tea consumption by herdsmen in 2015 were used. Based on the deterministic assessment model， the daily intake of fluoride from brick tea by herdsmen was calculated.ResultsThe average fluorine content of brick tea was 464.32 mg/kg， the maximum was 1 206.00 mg/kg， and the over standard rate was 74.74% （213/285）， among which the over standard rate of Kang brick tea was the highest （100%， 12/12）. The average intake level of fluoride was 0.048 mg/kg BW per day， which was close to the tolerable upper intake levels （UL）. The daily fluoride intake of high-consumption group （P95） was 0.177 mg/ kg BW， which was 3.1 times that of UL. The average daily intake of fluoride from brick tea by female consumers was 1.3 times that of men.ConclusionThe concentration of fluoride in brick tea was high， and fluoride might cause health risk to tea drinkers especially for high-consumption groups. Some effective measures should be taken to solve this problem.

Fluoride is one of the important trace elements of human life and health. A proper amount of fluoride is beneficial to health. Excessive intake of fluoride will lead to dental fluorosis, bone fluorosis and urolithiasis, and serious excessive intake will affect the human central nervous system, endocrine hormone levels and reproductive system. The same lack of fluorine can also cause dental caries, Kaschin-beck disease signs and osteoporosis symptoms and cause hematopoietic dysfunction. Due to the chemical characteristics of fluorine, the forms of fluorine in the natural environment are very complex, and the transformation between different forms needs further study. How to quickly and accurately determine the content of fluorine in soil, rocks and minerals is of great significance for evaluating regional geochemical behavior and preventing fluorine-related diseases in humans.In this paper, the research progress of fluorine analysis and testing technology in soil, rocks and minerals in recent years is described. The methods, reagents and processes of sample pretreatment are summarized. The matrix correction, interference control, performance and application status of different testing methods are reviewed. In order to ensure the accuracy and reliability of the test results, it is necessary to eliminate the interference of metal cation, matrix effect and particle size validity, select the appropriate pretreatment and detection technology, reduce the detection limit, and constantly improve the accuracy and precision of the test.At present, the commonly used pretreatment methods mainly include pressed powder pellet, fusion, steam distillation, high temperature combustion hydrolysis, alkali fusion and acid dissolution. Among them, the pressed powder pellet method is simple, employs nondestructive analysis, has high sample preparation efficiency, and can meet the requirements of pretreatment of fluorine in large quantities of soil. The fusion method can effectively reduce the particle size effect and mineral effect, but different matrix samples need to use different oxidants, the preparation process is complicated, and requires high experience of the sample maker. Steam distillation and high temperature combustion hydrolysis are mainly used in rock sample treatment. The interference of metal ions can be effectively reduced by steam distillation or high temperature combustion hydrolysis. The test results of the samples treated by the alkali fusion method are stable and widely used, but there is metal ion interference, which leads to low fluorine test results. The acid dissolution method is used mainly for the decomposition of some specific ore samples, such as phosphate ore, and is rarely used at present.The commonly used determination methods include the ion selective electrode method, ion chromatography, XRF method, spectrophotometry, colorimetric method and liquid chromatography. Among them, the ion selective electrode method is mature and widely used because of its high accuracy and good stability. The detection limit of ion chromatography is low, but the test efficiency is low. X-ray fluorescence spectrometry uses lossless injection, simple environmental protection and can measure multiple elements at the same time. The colorimetric method is not accurate enough, the stability of the method is poor, the analysis steps are more complicated, and it is not suitable for the analysis of daily samples. Liquid chromatography is rarely used at present because of the expensive pretreatment equipment.At present, the alkali fusion method (accounting for 26%) is widely used as the most important pretreatment means, but it has many shortcomings, such as large reagent consumption, long process, complicated steps and cationic interference. Further research and practice are needed to optimize testing techniques and methods. The high temperature combustion hydrolysis method (accounting for 13%) and steam distillation method (accounting for 18%) can reduce cationic interference, but their cumbersome steps and special expensive equipment are currently used less. The ion selective electrode method accounted for more than one third of the test methods. Currently, the pre-treatment method using alkali fusion-ion selective electrode method is one of the most effective test technologies for the determination of fluorine content in soil, rocks and minerals.Pressed powder pellet method (accounting for 17%) has potential research value because of its unique non-destructive injection, simple, fast and environmental protection, and the matching XRF method (accounting for 29%) can realize multi-element combined measurement, which has significant advantages in stability and precision. The future research direction of fluorine determination by X-ray fluorescence spectrometry will be how to reduce the detection limit of the method and eliminate the particle size effect and mineral effect. Other analysis and testing techniques are not recommended because of cumbersome procedures, expensive pre-treatment equipment, only certain types of samples can be processed, and limitations of testing methods.As fluorine is a light element and its occurrence forms are complex and diverse, it is necessary to select appropriate analysis and testing techniques according to the characteristics of sample types.The main research directions of fluorine analysis and testing technology in soil, rocks and minerals and pretreatment methods are focused on non-destructive analysis of samples, safety and environmental protection, rapid and other aspects, and the main research directions of testing technology are focused on the establishment of multi-element simultaneous determination. In conclusion, the determination of fluorine in soil, rocks and minerals by pressed powder pellet-X-ray fluorescence spectrometry has important research value.

Titanium is the most commonly used material for the production of implants,but titanium dental implants are not immune to corrosion due to the complex oral cavity environments.The concentration of titanium ions increases in tissues around the implants due to the corrosion,leading to allergic reactions and inflammation,which hinder the long-term safe service of implants.In this paper,the research progress on corrosion of titanium implants was reviewed based on different types of influencing factors,including corrosion due to the effect of inorganics and organics,corrosion due to microorganisms and tribocorrosion.Besides,the future research was prospected.

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Copyright of Hydrometallurgy of China is the property of Hydrometallurgy of China Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Fluoride is one of the important trace elements of human life and health. A proper amount of fluoride is beneficial to health. Excessive intake of fluoride will lead to dental fluorosis, bone fluorosis and urolithiasis, and serious excessive intake will affect the human central nervous system, endocrine hormone levels and reproductive system. The same lack of fluorine can also cause dental caries, Kaschin - beck disease signs and osteoporosis symptoms and cause hematopoietic dysfunction. Due to the chemical characteristics of fluorine, the forms of fluorine in the natural environment are very complex, and the transformation between different forms needs further study. How to quickly and accurately determine the content of fluorine in soil, rocks and minerals is of great significance for evaluating regional geochemical behavior and preventing fluorine-related diseases in humans. In this paper, the research progress of fluorine analysis and testing technology in soil, rocks and minerals in recent years is described. The methods, reagents and processes of sample pretreatment are summarized. The matrix correction, interference control, performance and application status of d ifferent testing methods are reviewed. In order to ensure the accuracy and reliability of the test results, it is necessary to eliminate the interference of metal cation, matrix effect and particle size validity, select the appropriate pretreatment and detection technology, reduce the detection limit, and constantly improve the accuracy and precision of the test. At present, the commonly used pretreatment methods mainly include pressed powder pellet, fusion, steam distillation, high temperature combustion hydrolysis, alkali fusion and acid dissolution. Among them, the pressed powder pellet method is simple, employs nondestructive analysis, has high sample preparation efficiency, and can meet the requirements of pretreatment of fluorine in large quantities of soil. The fusion method can effectively reduce the particle size effect and mineral effect, but different matrix samples need to use different oxidants, the preparation process is complicated, and requires high experience of the sample maker. Steam distillation and high temperature combustion hydrolysis are mainly used in rock sample treatment. The interference of metal ions can be effectively reduced by steam distillation or high temperature combustion hydrolysis. The test results of the samples treated by the alkali fusion method are stable and widely used, but there is metal ion interference, which leads to low fluorine test results. The acid dissolution method is used mainly for the decomposition of some specific ore samples, such as phosphate ore, and is rarely used at present. The commonly used determination methods include the ion selective electrode method, ion chromatography, XRF method, spectrophotometry, colorimetric method and liquid chromatography. Among them, the ion selective electrode method is mature and widely used because of its high accuracy and good stability. The detection limit of ion chromatography is low, but the test efficiency is low. X-ray fluorescence spectrometry uses lossless injection, simple environmental protection and can measure multiple elements at the same time. The colorimetric method is not accurate enough, the stability of the method is poor, the analysis steps are more complicated, and it is not suitable for the analysis of daily samples. Liquid chromatography is rarely used at present because of the expensive pretreatment equipment. At present,the alkali fusion method (accounting for 26%) is widely used as the most important pretreatment means, but it has many shortcomings, such as large reagent consumption, long process, complicated steps and cationic interference. Further research and practice are needed to optimize testing techniques and methods. The high temperature combustion hydrolysis method (accounting for 13%) and steam distillation method (accounting for 18%) can reduce cationic interference, but their cumbersome steps and special expensive equipment are currently used less. The ion selective electrode method accounted for more than one third of the test methods. Currently, the pre- treatment method using alkali fusion - ion selective electrode method is one of the most effective test technologies for the determination of fluorine content in soil, rocks and minerals. Pressed powder pellet method (accounting for 17%) has potential research value because of its unique nondestructive injection, simple, fast and environmental protection, and the matching XRF method ( accounting for 29%) can realize multi - element combined measurement, which has significant advantages in stability and precision. The future research direction of fluorine determination by X-ray fluorescence spectrometry will be how to reduce the detection limit of the method and eliminate the particle size effect and mineral effect. Other analysis and testing techniques are not recommended because of cumbersome procedures, expensive pre-treatment equipment, only certain types of samples can be processed, and limitations of testing methods. As fluorine is a light element and its occurrence forms are complex and diverse, it is necessary to select appropriate analysis and testing techniques according to the characteristics of sample types. The main research directions of fluorine analysis and testing technology in soil, rocks and minerals and pretreatment methods are focused on non-destructive analysis of samples, safety and environmental protection, rapid and other aspects, and the main research directions of testing technology are focused on the establishment of multi-element simultaneous determination. In conclusion, the determination of fluorine in soil, rocks and minerals by pressed powder pelletX-ray fluorescence spectrometry has important research value. [ABSTRACT FROM AUTHOR]

Mine water poses severe threats to the quality of the water supply and ecological environment of the Shendong mining areas owing to its excessive fluoride (F-) content. Previous studies have revealed the spatial distribution, sources, and geochemical controls that cause F- enrichment in Shendong mine water. However, seasonal distribution and quality assessment of elevated fluoride in the mine water are not fully understood. In total, 35 water samples were collected from the Shendong coal-mining area during the dry and wet seasons, and the seasonal distribution and geochemical sources were characterized and discussed. In addition, the quality assessment posed by mine water fluoride to environment was assessed.The results showed that the F- contents of mine water samples ranged from 0.16 to 13.96mg/L (mean 4.43mg/L) and from 0.16 to 17.60mg/L (mean 4.89mg/L) during the dry and wet seasons, respectively. The F- content of mine water in dry season is obviously higher than that in wet season. F- was significantly negatively correlated with Ca2+ and positively correlated with HCO3- and Na+ in mine water. Important factors identified as having an effect on F- in mine water included the dissolution of F-bearing minerals, cation exchange and competitive adsorption. In addition, the quality assessment of high groundwater fluoride to environment showed that 100% and 66.67% of low F-mine water are suitable for ecological irrigation, while 92.00% and 96.15% of high F-mine water are not suitable for ecological irrigation during the dry and wet seasons, respectively. [ABSTRACT FROM AUTHOR]

BackgroundIt has been found that fluoride may cause cell damage by inducing intracellular calcium overload. Store-operated calcium entry (SOCE) plays an important role in maintaining intracellular calcium homeostasis, but the effect of fluoride on renal SOCE is unknown.ObjectiveTo explore the renal toxicity and the expression levels of the key proteins of SOCE, stromal interaction molecule 1 (STIM1) and calcium release-activated calcium modulator 1 (ORAI1) in the kidney tissues of mice exposed to fluoride subchronically.MethodsTwenty male ICR mice were randomly divided into four groups with five mice in each group, including 0 (control group), 0.3, 3, and 30 mg·L−1 fluoride groups. The mice were given drinking water containing designed fluoride for 12 weeks. Body weight and liver and kidney organ coefficients of the mice were measured after the exposure; histopathological changes of the mouse kidney were observed; 24 h urine was collected at the end of 12 weeks of exposure to determine the levels of urine creatinine (UCr), urine calcium (UCa), albumin (ALB), and β2-microglobulin (β2-MG); the protein expression levels of STIM1 and ORAI1 in the kidney were detected by Western blotting; the fluorescence co-localization of STIM1 and ORAI1 was used to further verify the expression levels of STIM1 and ORAI1.ResultsAfter the exposure, there were no differences in body weight as well as liver and kidney organ coefficients among the groups (P > 0.05). Under optical microscope, the renal tubular cell showed degeneration, apical protrusion, shedding, and dilation in the 3 and 30 mg·L−1 fluoride groups. There was no statistical difference in UCr among the mice in each group (P > 0.05). Compared with the control group, the levels of UCa adjusted by UCr in the 3 and 30 mg·L−1 fluoride groups were (0.075±0.014) and (0.081±0.012) mol·mol−1 (represent by UCr per mol), which had a rising trend but showed no statistical difference. No difference was identified in the level of ALB among the groups (P > 0.05). The levels of β2-MG showed difference in different exposure groups, and the level of urine β2-MG in the 30 mg·L−1 fluoride group was (0.077±0.014) g·mol−1, higher than that in the control group (P

In recent years, the problem of excessive fluoride in mine water is particularly prominent, which not only affects the water quality of reuse after treatment, but also endangers human health.Therefore, the study herein developed a novel adsorbent for fluoride -coffee residual based biochar(CRB)by applying the waste coffee residue as raw material and chemical activation, to realize the purpose of solid waste resource utilization and fluoride removal from mine water at the same time.The authors firstly optimized the preparation protocols of CRB through single factor, including the type of activator, activator concentration and activation temperature; then evaluated the adsorption efficiency of fluoride for CRB before and after optimization by kinetic and isothermal adsorption experiments; finally investigated the adsorption mechanism of fluoride for CRB after optimization(O-CRB)by surface physicochemical characterization.The results showed that the more favorable CRB for fluoride was prepared at the ZnCl2 concentration of 4 mol/L and the activation temperature of 400 ℃.The maximum adsorption capacity of O-CRB for fluoride was 2.20 mg/g, which was 1.30 times higher than that of CRB before activation.In addition, compared with CRB, O-CRB exhibited higher amount of mesopore volume and specific surface area, as well as more oxygen containing functional groups(-COOH)and surface Zeta potential.Thus, the amount of chloride on the O-CRB surface decreased obviously(3.27 % to 0.61 %)after fluoride adsorption, whereas the amount of fluoride increased significantly(0.76 % to 10.34 %).This suggested that the adsorption of fluoride for O-CRB was mainly attributed to the electrostatic adsorption and ion exchange.

Objective：To prepare the novel fluoride loaded poly(prolylene carbonate)(PPC)/sodium fluoride (NaF) dental patch based on PPC and explore its remineralization property and in vitro cytotoxicity, and to clarify its effect of fluorine-containing patches with different concentrations of fluoride in promoting the remineralization of demineralized enamel, and to provide the reference for its clinical application. Methods：The PPC/NaF dental patch with different mass fractions of sodium fluoride(0, 0. 5%, 2. 5%, and 5.0%)were prepared by melt-blending method. The enamel blocks were prepared with extracorporeal tooth and randomly divided into PPC group, 0. 5%PPC/NaF group, 2. 5%PPC/NaF group, and 5.0%PPC/NaF group according to different contents of fluoride in the dental patches, and there were 10 samples in each group. The morphology of surface of enamel specimens was observed under scanning electron microscope (SEM), the microhardness of the enamel surface before and after demineralization and after remineralization was measured by microhardness tester, and the microhardness recovery percentage(SMHR)was calculated. The mouse fibroblast L929 cells were co-cultured with the PPC/NaF dental patch extract, and CCK-8 test was used to detect the relative proliferation rate(RGR)of the fibroblast L929 cells of the mice in various groups, and its cytotoxicity level was evaluated. Results：The microhardness of the enamel specimens in various groups after demineralization was significantly lower than that before demineralization(P<0.05). After being treated with PPC/NaF tooth patches with different contents of sodium fluoride, the microhardness of the enamel specimens in various groups was significantly higher than that before remineralization(P<0.05), but still lower than that before demineralization(P<0.05). The SMHR of enamel specimens in each group from high to low was 5.0% PPC/NaF group, 2. 5% PPC/NaF group, 0. 5% PPC/NaF group, and PPC group. The SEM results showed that the number of pores on the surface of the enamel specimens in PPC group was still large, and the irregular granular sediments were seen；in 0. 5%PPC/NaF group, the number of pores on the enamel surface was decreased significantly, and the obvious enamel collapse was still seen on the surface and mineral crystal deposition was loose and uneven；in 2. 5% PPC/NaF group, there were almost no pores on the enamel surface, and the enamel surface was regular and covered with a large number of needle-like crystals, which were densely arranged；in 5.0% PPC/NaF group, the enamel surface was covered with a large number of needle-like or irregular granular crystals and layered sediments were seen in some areas. Compared with PPC group, the RGR of the fibroblast L929 cells of the mice in 5.0% PPC/NaF group was decreased significantly(P<0.05). The RGR of the fibroblast L929 cells after treated with PPC/NaF tooth patches with different contents of fluoride in various groups was greater than 75%, and the cytotoxicity grade was 0 or 1. Conclusion：PPC/NaF dental patch can effectively promote the demineralization of the demineralized enamel without cytotoxicity；with the increasing of fluorine concentration, its remineralization is also enhanced. [ABSTRACT FROM AUTHOR]

Yan’an Formation groundwater is an important underground drinking aquifer in the Shendong mining area,and the level of its F-content directly affects the safety of drinking water and the surrounding ecological environment. However,the characteristics of F-content,spatial distribution and formation mechanism in groundwater of the Yan’an Formation in this region have received little attention. The project team systematically collected 30 groups of Yan’an Formation groundwater in August-September 2020,and explored the characteristics of F-content,spatial distribution and formation mechanism in Yan’an Formation groundwater in terms of mineral dissolution and precipitation,evaporation,cation exchange,competitive adsorption and anthropogenic pollution effects by using Piper diagram,correlation analysis,PHREEQC simulation,etc. The results showed that the concentration of F-in groundwater of the Yan’an Formation in the Shendong mining area ranged from ND to 17. 60 mg / L,with an average value of 4. 55 mg / L. Compared with the national sanitary standard for domestic drinking water （GB 5749—2006） （1. 0 mg / L）,73. 3% of the samples exceeded the standard. High TDS,Cl-,HCO3-,Na+and low Ca2+and Mg2+water environment are favorable for F-enrichment,and Na-HCO3type,Na-HCO3-Cl type and Na-HCO3-SO4type are the main hydrochemical types of high fluoride water. Fluoride-bearing mineral dissolution is an important source of groundwater F-in the Yan’an Formation. The salt effect under evaporite dissolution and silicate weathering reduces the solubility of fluoride-bearing minerals and promotes the dissolution of F; cation exchange further accelerates the dissolution of fluoride-bearing minerals through sodium-calcium transfer,adsorbed state fluorine under competitive adsorption also provides an additional source of groundwater F-. However,the effects of evaporation and human activities on the elevated F-content of groundwater in the Yan’an Formation are small and negligible. The results provide a scientific basis for the safety of water quality for local drinking water and sustainable development of ecological environment. [ABSTRACT FROM AUTHOR]

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The citric acid, ethylenediamine, salicylic acid and Fe(III) were used as raw materials to synthesize a composite fluorescent carbon dot (RCDs-Fe(III)) that specifically responds to fluoride ions. Subsequently, through a series of experiments, the conditions of carbon dot synthesis and fluoride ion detection were optimized. The optimal raw material ratio for carbon point synthesis is: 2 mL ethylenedia. mine, 2 g citric acid and 0. 2 g salicylic acid; the optimal detection conditions are: the reaction system solvent is a hydrochloric acid solution w让h pH 5. 0, thE Fe(III) concentration is 150 mg/L, the composite carbon dot concentration is 0.5%, and the carbon dot exc让ation and emission wavelengths are 370 nm and 460 nm, respectively. Under the optimal detection conditions, the linear range of fluoride ion detection by RCDs-Fe(III) is 1 〜25 mg/L, and the detection limit is 0. 82 mg/L. Finally, the composite carbon dots were used for the determination of fluoride ion in toothpaste, and the results were consistent with the comparison method. [ABSTRACT FROM AUTHOR]

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Copyright of Journal of China Medical University is the property of Journal of China Medical University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Inorganic Analytical Chemistry / Zhongguo Wuji Fenxi Huaxue is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Inorganic Analytical Chemistry / Zhongguo Wuji Fenxi Huaxue is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective To investigate the oral health behavior of urban and rural students in the 12~15 year age group in Guangdong Province, aiming to provide informational support for adolescent oral health care. Methods A multistage stratified sampling method with equal capacity and simple random sampling was applied to obtain representative samples. A total of 7 680 students aged 12 to 15 were selected from Guangdong Province, with 1 920 in each age group of 12, 13, 14 and 15 years; half were male and half were female, and half were from urban areas and half were from rural areas. According to the Fourth National Oral Health Epidemiology Questionnaire Survey Program, a standard questionnaire was designed to conduct on-the-spot investigations on sugar intake, brushing, dental floss usage, fluoride toothpaste usage. Results ① Eating before a meal and before bed: the proportion of sweet snacks, sweet drinks and sugary drinks consumed ≥2 times/day was higher in the rural group than in the urban group (P < 0.001), with only sugary drinks consumed significantly differently by age (P < 0.001). ② The rural group had a significantly lower proportion of brushing ≥ 2 times/day, flossing habits and fluoride toothpaste habits than the urban group (P < 0.001), whereas only fluoride toothpaste habits were significantly different across age groups (P < 0.001). Conclusions Among the students aged 12 to 15 in Guangdong Province, the rural group had a higher proportion of consuming desserts, sweet drinks and sweetened drinks. The proportion of brushing ≥ 2 times/day was lower, and the usage rate of floss and fluoride toothpaste was lower.

Groundwater is one of the major water sources for production, living, and agricultural irrigation in the Yinchuan Plain. Owing to the influence of the regional environmental background and long-term effects of human activities, groundwater quality is generally inferior. To deeply analyze the formation mechanism and source of hydrochemical components in groundwater in the Yinchuan Plain, the traditional hydrochemical graphic method and mathematical statistics and principal component analysis-multivariate linear statistical model were used. Based on inorganic component contents of 100 phreatic water samples and 46 confined groundwater samples, the hydrochemical characteristics and quality status, spatial distribution of over-limit toxicological components, and contribution rate of hydrochemical components were analyzed. The results showed that the chemical components of groundwater were controlled by rock weathering and evaporation concentration. Dissolution-enrichment （F1）, original geological environment （F2）, and human activities（F3） were the principal factors that influenced groundwater hydrochemistry with the contribution rates of 73.67%, 14.45%, and 11.88%, respectively. The major over-limit toxicity indices in groundwater were NO 3 - -N and F - . High NO 3 - -N phreatic water was mainly influenced by agriculture activities, followed by the discharge of domestic sewage. Enrichment of groundwater F - was mainly caused by leaching of F-bearing minerals and cation exchange adsorption.

In this study, absorption, transportation and bioavailability of fluorine in different extracts of a dark tea were evaluated in the Caco-2 cell line model. The results show that the fluorine contents in different extracts of dark tea were significantly different. The fluorine content of the crude polysaccharide fraction (RTP) was the highest, which was 2.17 times that of the water extract (TE). Fluorine content in dialyzed polysaccharide (DTP) was significantly reduced, which was only 1/22 of the fluorine content in RTP and 1/10 of the fluorine content in TE. The forward and reverse transport of fluorine in cell model had time and dose effects, and increased with the increase of time and concentration. After the first 1 h treatment, the forward and reverse transport of fluorine in NaF was the highest, while that in DTP was the lowest, which were significantly different from other treatments. There was no significant difference between the TE and RTP treatments. The apparent permeability coefficient (Papp) decreased with the prolonging of treatment time. The Papp of fluorine in NaF was more than 1x10-5 cm·s-1 within 4 h, indicating its bioavailability was good. The Papp of fluorine in TE and RTP decreased to less than 1x10-5 cm·s-1 after 2 h of treatment, indicating its bioavailability was moderate. the Papp of fluorine in DTP was the smallest at all stages, and was less than 1x10-5 cm·s-1 after 1 h of treatment, indicating its bioavailability was low. Fluorine in NaF, TE or DTP was mainly transported by passive diffusion within the tested concentration range, while fluorine in RTP had an active transport at a higher concentration. In conclusion, in the intestinal epitheliums model, the fluorine in the dark tea has lower bioavailability than that in NaF, and the binding form of the fluorine in the dark tea might affect its bioavailability. [ABSTRACT FROM AUTHOR]