[Pollution status and exposure assessment of lead, cadmium, total mercury and total arsenic in grains on sale from Shaanxi Province, 2002-2018].

OBJECTIVE: To investigate the pollution status of lead, cadmium, total mercury and total arsenic in grains sold in Shaanxi Province, and to analyze the potential risk of dietary exposure. METHODS: A total of 1873 samples of wheat, wheat flour, rice, maize and their products were randomly collected in circulation. The contents of lead and cadmium were determined by atomic absorption spectrophotometry and inductively coupled plasma mass spectrometry, and total mercury and arsenic were determined by atomic fluorescence spectrometry. The pollution status of four elements in grains was evaluated by single factor pollution index method, margin of exposure(MOE) was used to assess lead exposure, cadmium exposure was assessed by the ratio of estimated monthly intake(EMI) to provisional tolerable monthly intake(PTMI), and exposure to mercury and arsenic was assessed using the ratio of estimated weekly intake(EWI) to provisional tolerable weekly intake(PTWI). RESULTS: The average values of lead, cadmium, total mercury and total arsenic in grains sold in Shaanxi Province were 0.070, 0.022, 0.0079 and 0.030 mg/kg. The over-standard rates of lead, cadmium and total mercury were 6.30%, 1.39% and 4.43%. The average single factor pollution index of lead, cadmium, total mercury and total arsenic was less than 0.7; The MOE value of lead in grains was 0.99-18.41, the intake of cadmium in grains accounted for 19.08% of PTMI, and the intake of mercury and arsenic accounted for 10.28% and 10.67% of PTWI. CONCLUSION: Lead, cadmium, total mercury and total arsenic in all kinds of cereals sold in Shaanxi Province from 2002 to 2018 were less polluted and their intake was within the safe range.

[Analysis of internal exposure levels of manganese, cobalt, selenium and molybdenum in blood and urine among general population in parts of Shaanxi Province].

OBJECTIVE: To investigate the internal exposure levels of manganese(Mn), cobalt(Co), selenium(Se) and molybdenum(Mo) in blood and urine among the general population in parts of Shaanxi Province, and thereby to analyze their population distribution characteristics. METHODS: In 2017, a total of 720 subjects of general people aged 3-79 years were recruited from 5 counties in Shaanxi Province, by stratified random sampling method, blood and urine samples were collected, and the contents of Mn, Co, Se and Mo in blood and urine samples were detected by inductively coupled plasma mass spectrometry(ICP-MS). The test result were statistically analyzed according to different genders, regions and age groups. RESULTS: Among general people in Shaanxi Province, the median of Mn in blood and urine were separately 8. 43 and 0. 60 µg/L. The median of Mn in blood among males and females were 7. 99 and 8. 81 µg/L, the difference was statistically significant(P<0. 05), the difference of blood Mn between urban and rural areas was statistically significant(P<0. 05). The median of Co in blood and urine were separately 0. 13 and 0. 17 µg/L, the median of Co in blood among males and females were 0. 12 and 0. 15 µg/L, the median of Co in urine among males and females were 0. 16 and 0. 20 µg/L, the differences were statistically significant(P<0. 05), the differences of blood Co and urine Co in urban and rural areas were statistically significant(P<0. 05). The median of Se concentration in blood and urine were separately 73. 20 and 13. 30 µg/L, the median of Se in urine among males and females were 14. 40 and 12. 40 µg/L, the difference were statistically significant(P<0. 05), the differences of blood Se and urine Se in urban and rural areas were statistically significant(P<0. 05). The median of Mo concentration in blood and urine were separately 0. 60 and 50. 40 µg/L, the median of Mo in urine among males and females were 56. 60 and 43. 00 µg/L, the difference was statistically significant(P<0. 05), the difference of blood Mo between urban and rural areas was statistically significant(P<0. 05). Within the same gender, all indexes in whole blood(except female blood Se) were statistically significant among age groups(P<0. 05). The differences of male urine Co, urine Se, urine Mo and female urine Co among age groups were statistically significant(P<0. 05). CONCLUSION: Among general population in Shaanxi Province, the Mn, Co, Se and Mo levels in blood and urine are varied by gender age and area, the blood Se level is relatively low.

[Analysis of polycyclic aromatic hydrocarbons pollution characteristics in PM_(2. 5) in two districts of Xi'an City from 2016 to 2018].

OBJECTIVE: To analyze the pollution characteristics of polycyclic aromatic hydrocarbons(PAHs) in atmospheric PM_(2. 5) in Lianhu district and Yanta district of Xi'an City. METHODS: From 2016-2018, PM_(2. 5) samples were regularly collected at monitoring points in two districts of Xi'an City, and analyzed the content of naphthalene, acenaphthylene, fluorene, acenaphthene, phenanthrene, anthracene, fluoranthene, pyrene, chrysene, benz(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, dibenz(a, h)anthracene, benzo(g, h, i)perylene, indeno(1, 2, 3-cd)pyrene in the samples according to Ambient air and stationary source emissions-Determination of gas and particle-phase polycyclic aromatic hydrocarbons-High performance liquid chromatography(HJ 647-2013). The test result were analyzed and evaluated according to different years, regions and seasons. RESULTS: The median total PAHs mass concentrations(ΣPAHs) in Lianhu district and Yanta district were 11. 68 and 12. 53 ng/m~3, respectively, with no significant difference(P>0. 05). The ΣPAHs of the two districts were decreasing year by year(P<0. 05). The median ΣPAHs in Lianhu district and Yanta district were highest in winter(55. 50, 55. 61 ng/m~3) and lowest in summer(4. 62, 4. 57 ng/m~3). The top three single indicators of the median PAHs in Lianhu district were benz(b)fluoranthene(1. 90 ng/m~3), benzo(g, h, i)perylene(1. 67 ng/m~3) and chrysene(1. 34 ng/m~3), In Yanta district, they were benz(b)fluoranthene(1. 95 ng/m~3), benzo(g, h, i)perylene(1. 63 ng/m~3) and pyrene(1. 47 ng/m~3). The average mass concentrations of benzo(a)pyrene in Lianhu district and Yanta district were 1. 33 ng/m~3 and 1. 10 ng/m~3, respectively. Among all the samples, the qualified samples of benzo(a)pyrene accounted for 72. 75% of the total samples, and the Lianhu district and Yanta district were 71. 20% and 74. 30%, respectively(P>0. 05). CONCLUSION: The degree of atmospheric PAHs pollution in Xi'an had decreased year by year, and PAHs pollution in winter was more serious.

[Pollution characteristics and source analysis of metal and metalloid elements in PM_(2. 5)in two districts of Xi'an City from 2016 to 2018].

OBJECTIVE: To investigate the concentration levels and sources of 12 metals and metalloids in PM_(2. 5) in Lianhu district and Yanta district of Xi'an City. METHODS: From 2016-2018, PM_(2. 5) samples were collected periodically in the monitoring points of the two urban areas of Xi'an City. According to the ministry of environmental protection's "Ambient air and stationary source emission-Determination of metals in ambient particulate matter-Inductively coupled plasma/mass spectrometry"(HJ 657-2013) to determine the content of 12 metals and metalloid elements(Sb, Al, As, Be, Cd, Cr, Hg, Pb, Mn, Ni, Se, Ti). To analyse and evaluate of As, Cd, Pb and Hg according to the annual average reference concentration limit of "Ambient air quality standards"(GB 3095-2012). The main sources of 12 metals and metalloid elements were identified by enrichment factor(EF) and factor analysis. RESULTS: The total qualified rates of As, Cd, Pb and Hg were 46. 89%, 83. 03%, 99. 00% and 100. 00%, respectively, and the difference between the years was not statistically significant(P>0. 05). The average concentration of 12 metals and metalloid elements in PM_(2. 5) for three years was as follows: Al>Pb>Mn>As>Se>Sb>Cr>Cd>Ti>Ni>Hg>Be. The average concentration of As was 10. 10 ng/m~3, which was 1. 68 times exceeding the standard. The average concentration of Cd was 2. 68 ng/m~3, and the average concentration of Pb was 81. 26 ng/m~3. Concentration levels of As, Cd and Pb were on the decline. The EF values of Al, Cr, and Ni were all ≤1, the EF value of As was between 1 and 10. The EF values of Sb, Pb and Ti were all >10, and the EF values of Cd and Se were all >300. The main components of each year from 2016 to 2018 were 2, 2 and 3 respectively. The main component 1 included Pb, As, Cd, Se, Sb and Mn, and the main component 2 included Al, Cr and Ni. In 2018, the main component 3 included Ti(Ti was located in the main component 1 in 2016 and 2017). CONCLUSION: The sources of pollution of metals and metalloid elements in PM_(2. 5) in the atmosphere of Xi'an City mainly include motor vehicle emissions, coal combustion, industrial pollution and natural particles.

[Variation characteristics and meteorological influencing factors of PM_(2. 5)mass concentration in Xi'an City from 2015 to 2018].

OBJECTIVE: To master the variation characteristics of PM_(2. 5) mass concentration in Lianhu district and Yanta district of Xi'an City and its relationship with meteorological conditions. METHODS: From 2015 to 2018, according to the environmental monitoring data of six main urban areas in Xi'an City in 2012, including NO_2, SO_2, PM_(10), PM_(2. 5), CO and O_3, air samples were collected in the relatively heavy polluted Lianhu district and the relatively light Yanta district of Xi'an City. The mass concentration test of PM_(2. 5) was carried out in accordance with the Ministry of Environmental Protection's "Determination of atmospheric articles PM_(10) and PM_(2. 5) in ambient air by gravimetric method "(HJ 618-2011). According to the Ambient air quality standards(GB 3095-2012), the average daily secondary concentration limit(75 µg/m~3) was used for statistical analysis and evaluation according to different annual, regional and seasonal test result. Meteorological data of Xi'an City were collected, including daily average temperature, daily average pressure, daily average relative humidity, daily average wind speed, daily precipitation, maximum temperature and minimum temperature, and the relationship between PM_(2. 5)concentration and meteorological factors was analyzed. RESULTS: A total of 660 air samples were collected and qualified, the median concentration of PM_(2. 5) was 71 µg/m~3. 356 air samples were qualified, and the pass rate was 53. 94%. The sample pass rate for each year from high to low was 2017>2018>2016>2015(P<0. 001), The average level of PM_(2. 5) mass concentration from high to low was 2015>2016>2017>2018(P<0. 001). There was no significant difference in the sample pass rate and PM_(2. 5)mass concentration between Lianhu district and Yanta district(P>0. 05). The qualified rate of samples from high to low in different seasons was summer>spring> autumn>winter(P<0. 05). The average concentration of PM_(2. 5) in different seasons from high to low was winter>autumn>spring>summer(P<0. 001). Mean temperature, mean air pressure, average wind speed, average relative humidity, precipitation and lowest temperature were significantly correlated with PM_(2. 5) mass concentration(P<0. 001). The determination coefficients of multiple regression analysis of meteorological factors in Lianhu and Yanta regions were 0. 390 and 0. 373, respectively. CONCLUSION: The air quality in Lianhu district and Yanta district of Xi'an City had improved year by year, and the pollution of PM_(2. 5) in autumn and winter was more serious. Meteorological conditions affected the concentration level of PM_(2. 5) in the atmosphere.

[Analysis on monitoring results of toxicological indicators of rural drinking water in Shaanxi Province from 2016 to 2018].

OBJECTIVE: To understand the toxicological indexes of rural drinking water quality in 2016-2018 in Shaanxi Province. METHODS: From 2016 to2018, rural drinking water monitoring points were set up in all( 102) agriculture-related counties( districts) in Shaanxi Province. Each township selected 1-2 rural water supply systems for terminal water supply and terminal water and waste water for distributed water supply as monitoring points. A total of 18 284 monitoring points were set. Water samples were collected during the dry season from April to June and from July to September, according to the Standard Test Method for Drinking Water( GB/T 5750. 5-2006, GB/T5750. 6-2006, GB/T 5750. 8-2006). Carried out experimental analysis and collected water quality monitoring information through the "National Drinking Water Quality Monitoring Information System ". Experimental analysis according to the Standard Test Method for Drinking Water( GB/T 5750. 5-2006, GB/T 5750. 6-2006, GB/T5750. 8-2006); 11 toxicological indicators of the routine indicators were analyzed and evaluated according to the Standard of Drinking Water Hygiene( GB 5749-2006). RESULTS: From 2016 to 2018, the overall compliance rate of drinking water toxicology indicators in rural areas of Shaanxi Province was 81. 02%. The top four indicators exceeding the standard were fluoride( 9. 74%), nitrate nitrogen( 6. 09%) and hexavalent chromium. ( 4. 50%) and arsenic( 1. 44%), the other indicators exceeding the standard exceeds the range of 0. 01%-0. 32%. The difference of water quality compliance rates of cadmium, selenium, cyanide, fluoride and nitrate nitrogen in different years was statistically significant( P<0. 05), and the compliance rate of selenium, cyanide, fluoride and nitrate nitrogen increased with the year. Increasing trend( P<0. 05). The compliance rate of cadmium and selenium in the wet season was higher than that in the dry season, and the compliance rate of nitrate nitrogen in the dry season was higher than that in the wet season, the difference was statistically significant( P<0. 05). The compliance rate of arsenic, cadmium, hexavalent chromium, lead, selenium, fluoride and nitrate nitrogen in surface water were higher than that of groundwater( P < 0. 05). There was a statistically significant difference in the overall compliance rate of water toxicology between different water supply method in centralized water supply projects( P < 0. 001). The highest standard rate of water quality was observed in conventional water treatment, followed by sedimentation and filtration. There were 10, 10 and 4 types of over-standard indicators in Guanzhong, northern Shaanxi and southern Shaanxi, and the regional differences of 7 indicators including arsenic, cadmium, hexavalent chromium, lead, selenium, fluoride and nitrate nitrogen had statistics significance( P<0. 05). CONCLUSION: The overall compliance rate of toxicological indicators of drinking water in rural areas of Shaanxi Province is low, fluoride, nitrate nitrogen, hexavalent chromium and arsenic are serious and have obvious regional characteristics. In the future, we should focus on the excessive toxicological indicators, and ensure the safety and hygiene of drinking water from the aspects of water supply and treatment technology.

[Fluoride content in rural drinking water in Shaanxi Province during 2008-2018].

OBJECTIVE: To understand the fluoride index of drinking water quality and its trend in rural areas of Shaanxi Province since 2008, to evaluate the effect of water improvement on reducing fluoride. METHODS: In 2008-2018, rural drinking water monitoring points were set up in the jurisdiction of the agriculture-related counties( districts) in Shaanxi Province. Water samples were collected in the April-June dry seasons and July-September wet seasons, and tested according to the Standard Test Method for Drinking Water( GB/T 5750-2006). Collected and sorted water quality monitoring information through the National Drinking Water Quality Monitoring Information System, according to the Sanitary Standards for Drinking Water( GB 5749-2006), the comparison between groups and linear trend analysis were carried out according to different annual, water period, water source type, water supply mode and region. RESULTS: From 2008 to 2018, the overall compliance rate of fluoride in rural drinking water in Shaanxi Province was 93. 37%, the concentration of fluoride in water was in the range of0. 001-9. 880 mg/L, the median was 0. 370 mg/L, and the cumulative coverage of water quality fluoride exceeded the standard project was 3. 669 million. The difference of fluoride compliance rate in different years was statistically significant( χ~2= 120. 962, P<0. 001), and the fluoride compliance rate increased with the increase of the year( χ~2= 9. 241, P =0. 002), the fluoride compliance rate of surface water was higher than that of groundwater( χ~2= 1188. 563, P < 0. 001), there was a statistically significant difference in the compliance rate of fluoride in different water treatment processes in centralized water supply projects( χ~2= 2931. 231, P < 0. 001), the highest rate of fluoride in conventional treatment was 96. 63%( P < 0. 001), and the lowest disinfection rate was 84. 78%( P <0. 001). The distribution of drinking water sources in rural areas of Guanzhong and Northern Shaanxi was mainly groundwater, accounting for 88. 12% and 92. 25%, respectively, while Southern Shaanxi was dominated by surface water, accounting for69. 99%. There were significant differences in the fluoride compliance rates in Guanzhong region, Northern Shaanxi and Southern Shaanxi( χ~2= 1919. 335, P < 0. 001). Among them, the highest in Southern Shaanxi was 99. 84%( P < 0. 001), and the lowest in Northern Shaanxi was 89. 33%( P < 0. 001)( χ~2 SouthernShaanxi, Guanzhong= 1755. 724, χ~2 Southern Shaanxi, Northern Shaanxi= 2033. 8, χ~2 Northern Shaanxi, Guanzhong= 27. 535, P < 0. 001). The overall compliance rate of fluoride in water-reducing projects was 73. 80%, which cannot prove the trend of the overall compliance rate of fluoride in water-reducing projects with the year( χ~2= 3. 168, P = 0. 075). CONCLUSION: While achieving high result in the prevention and control of high fluorine water in Shaanxi Province, it is necessary to continue to implement effective measures to reduce fluorine content in rural drinking water, and to ensure the safety of drinking water from the aspects of water supply and treatment technology.

Tunable Neuromorphic Switching Dynamics via Porosity Control in Mesoporous Silica Diffusive Memristors.

In response to the growing need for efficient processing of temporal information, neuromorphic computing systems are placing increased emphasis on the switching dynamics of memristors. While the switching dynamics can be regulated by the properties of input signals, the ability of controlling it via electrolyte properties of a memristor is essential to further enrich the switching states and improve data processing capability. This study presents the synthesis of mesoporous silica (mSiO2) films using a sol-gel process, which enables the creation of films with controllable porosities. These films can serve as electrolyte layers in the diffusive memristors and lead to tunable neuromorphic switching dynamics. The mSiO2 memristors demonstrate short-term plasticity, which is essential for temporal signal processing. As porosity increases, discernible changes in operating currents, facilitation ratios, and relaxation times are observed. The underlying mechanism of such systematic control was investigated and attributed to the modulation of hydrogen-bonded networks within the porous structure of the silica layer, which significantly influences both anodic oxidation and ion migration processes during switching events. The result of this work presents mesoporous silica as a unique platform for precise control of neuromorphic switching dynamics in diffusive memristors.

3D-structured mesoporous silica memristors for neuromorphic switching and reservoir computing.

Memristors are emerging as promising candidates for practical application in reservoir computing systems that are capable of temporal information processing. Here, we experimentally implement a physical reservoir computing system using resistive memristors based on three-dimensional (3D)-structured mesoporous silica (mSiO2) thin films fabricated by a low cost, fast and vacuum-free sol-gel technique. The in situ learning capability and a classification accuracy of 100% on a standard machine learning dataset are experimentally demonstrated. The volatile (temporal) resistive switching in diffusive memristors arises from the formation and subsequent spontaneous rupture of conductive filaments via diffusion of Ag species within the 3D-structured nanopores of the mSiO2 thin film. Besides volatile switching, the devices also exhibit a bipolar non-volatile resistive switching behavior when the devices are operated at a higher compliance current level. The implementation of mSiO2 thin films opens the route to fabricate a simple and low cost dynamic memristor with a temporal information process functionality, which is essential for neuromorphic computing applications.

Flexible Memristor Devices Using Hybrid Polymer/Electrodeposited GeSbTe Nanoscale Thin Films.

We report on the development of hybrid organic-inorganic material-based flexible memristor devices made by a fast and simple electrochemical fabrication method. The devices consist of a bilayer of poly(methyl methacrylate) (PMMA) and Te-rich GeSbTe chalcogenide nanoscale thin films sandwiched between Ag top and TiN bottom electrodes on both Si and flexible polyimide substrates. These hybrid memristors require no electroforming process and exhibit reliable and reproducible bipolar resistive switching at low switching voltages under both flat and bending conditions. Multistate switching behavior can also be achieved by controlling the compliance current (CC). We attribute the switching between the high resistance state (HRS) and low resistance state (LRS) in the devices to the formation and rupture of conductive Ag filaments within the hybrid PMMA/GeSbTe matrix. This work provides a promising route to fabricate flexible memory devices through an electrodeposition process for application in flexible electronics.

[Terahertz spectroscopic investigation of crystalline beta-D-galactopyranose].

In order to deeply understand the spectral characteristics of beta-D-galactopyranose in the terahertz region, terahertz time-domain spectroscopy was used to measure the absorption coefficient and refractive index in the frequency range 0.3-3.0 THz at room temperature, and Fourier transform infrared spectroscopy was also used to obtain the absorption spectrum between 1.5 and 19.5 THz. In parallel with the experimental study, the 6-311+G * * basis set and density functional theory(DFT) were applied to obtain the structure and vibrational frequencies of the isolated beta-D-galactopyranose molecule at in phase. The observed vibrational spectra were assigned according to the DFT calculations. Results show that the theoretical calculations are in good agreement with the experimental data except somewhat blue shifts due to the intermolecular interactions. The observed resonances at the high frequency above 6 THz originate from distinct intra-molecular vibrational modes, while at the low frequency below 6 THz the observed resonances are dominated by vibrations of hydrogen bonds between the molecules or phonon modes. The comparison of experimental and theoretical studies shows that far-infrared absorption features are highly sensitive to the structure and spatial arrangement of molecules.

Cullin 4A is associated with epithelial to mesenchymal transition and poor prognosis in perihilar cholangiocarcinoma.

AIM: To explore the functional role of cullin 4A (CUL4A), a core subunit of E3 ubiquitin ligase, in perihilar cholangiocarcinoma (PHCC). METHODS: The expression of CUL4A in PHCC cell lines was evaluated by Western blot and quantitative reverse transcription-polymerase chain reaction. Immunohistochemistry (IHC) was adopted to investigate the relationship between CUL4A expression and clinicopathological characteristics of PHCC. Univariate analysis and multivariate regression analysis were performed to analyze the risk factors related to overall survival (OS) and progression-free survival (PFS) of PHCC patients. Wound healing, Transwell and Matrigel assays were utilized to explore the function of CUL4A in PHCC metastasis. Furthermore, expression of epithelial to mesenchymal transition (EMT) markers was verified in cells with CUL4A knockdown or overexpression. The relationship between CUL4A expression and E-cadherin expression was also analyzed by IHC assay. Finally, the role of ZEB1 in regulating CUL4A mediated PHCC was detected by IHC, Western blot, Transwell and Matrigel assays. RESULTS: CUL4A overexpression was detected in PHCC cell lines and clinical specimens. Clinicopathological analysis revealed a close correlation between CUL4A overexpression and tumour differentiation, T, N and TNM stages in PHCC. Kaplan-Meier analysis revealed that high CUL4A expression was correlated with poor OS and PFS of PHCC patients. Univariate analysis identified the following four parameters as risk factors related to OS rate of PHCC: T, N, TNM stages and high CUL4A expression; as well as three related to PFS: N stage, TNM stage and high CUL4A expression. Further multivariate logistic regression analysis identified high CUL4A expression as the only independent prognostic factor for PHCC. Moreover, CUL4A silencing in PHCC cell lines dramatically inhibited metastasis and the EMT. Conversely, CUL4A overexpression promoted these processes. Mechanistically, ZEB1 was discovered to regulate the function of CUL4A in promoting the EMT and metastasis. CONCLUSION: CUL4A is an independent prognostic factor for PHCC, and it can promote the EMT by regulating ZEB1 expression. CUL4A may be a potential therapeutic target for PHCC.

Expression and prognostic significance of livin, caspase-3, and ki-67 in the progression of human ampullary carcinoma.

Livin is a new member of the inhibitor of apoptosis proteins family of proteins that interacts with downstream caspases, such as caspase-3, caspase-7, and caspase-9, however, its role in human ampullary carcinoma has not been clearly defined. Immunohistochemistry was used to evaluate tissue samples from patients with ampullary carcinomas (n=71) using antibodies against livin, Ki-67 (a proliferation marker), and caspase-3. Livin was detected in 33/71 cases (in the cytoplasm of all and in the nucleus of only 2 cases). High livin expression correlated with cell differentiation, tumor-node-metastasis stage, and lymph node metastasis (P=0.001, P<0.001, and P=0.028, respectively). Caspase-3 and Ki-67 expression were significantly associated with differentiation (P<0.001, P=0.008, respectively). There was a significant negative correlation between livin and caspase-3 (r=-0.575, P<0.001), and a positive correlation between livin and Ki-67 (r=0.308, P=0.009). Survival of patients with high livin expression was shorter compared with that of patients with low livin expression (P=0.001). Expression of caspase-3 was not associated with overall survival in this cohort (P=0.335). Livin expression was an independent prognostic factor (hazard ratio 2.693, P=0.017), as was lymph node metastasis (hazard ratio 4.959; P<0.001). In this study livin expression significantly correlated with the proliferation marker Ki-67, but was negatively correlated with caspase-3 expression. These data suggest that livin may be a valuable prognostic factor for human ampullary carcinoma.