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The three-dimensional coordination polymer poly[[bis(μ3-2-aminoacetato)di-μ-aqua-μ3-(naphthalene-1,5-disulfonato)-hexasilver(I)] dihydrate], {[Ag6(C10H6O6S2)(C2H4NO2)4(H2O)2]·2H2O} n, based on mixed naphthalene-1,5-disulfonate ( L1) and 2-aminoacetate ( L2) ligands, contains two AgI centres (Ag1 and Ag4) in general positions, and another two (Ag2 and Ag3) on inversion centres. Ag1 is five-coordinated by three O atoms from one L1 anion, one L2 anion and one water molecule, one N atom from one L2 anion and one AgI cation in a distorted trigonal-bipyramidal coordination geometry. Ag2 is surrounded by four O atoms from two L2 anions and two water molecules, and two AgI cations in a slightly octahedral coordination geometry. Ag3 is four-coordinated by two O atoms from two L2 anions and two AgI cations in a slightly distorted square geometry, while Ag4 is also four-coordinated by two O atoms from one L1 and one L2 ligand, one N atom from another L2 anion, and one AgI cation, exhibiting a distorted tetrahedral coordination geometry. In the crystal structure, there are two one-dimensional chains nearly perpendicular to one another (interchain angle = 87.0°). The chains are connected by water molecules to give a two-dimensional layer, and the layers are further bridged by L1 anions to generate a novel three-dimensional framework. Moreover, hydrogen-bonding interactions consolidate the network. [ABSTRACT FROM AUTHOR]

For crossing to the real condition of a neural system, considering the network composed of Fitzhugh Nagumo neurons with time delay, it was found that not a single firing but a burst of firing fall into synchronization, and they pop out alternatively, this benefits the segmentation of patterns in time. For an input pattern which is an overlapped superposition of several stored patterns, it is shown that the proposed neuronal network model is capable of segmenting out each pattern one after another in the time domain as synchronous bursting of a subgroup of neurons, and if a corrupted input pattern is presented, the network is shown to he able to retrieve one learnt before, that is it has the function of associative memory. [ABSTRACT FROM AUTHOR]

Global warming and regional extreme climates will lead to unbalanced rainfall, melting glaciers, and permafrost degradation in alpine and arid mountain plains, thereby changing the regional hydrological cycle. The relationship between surface water and groundwater conversion is one of the important scientific issues of hydrological cycle climate response in alpine arid areas. Taking the Datong River Basin at the southern foot of the Qilian Mountains as the study area, based on 119 sets of basic hydrochemical parameters and deuterium-oxygen isotope data, using multivariate statistical analysis and isotopic techniques, the hydrochemical characteristics of surface water and groundwater in the basin and their mutual transformation process were studied. The results showed that the surface water was HCO 3 -Mg·Ca type, which was mainly controlled by rock weathering, whereas the groundwater was HCO 3 -Mg·Ca type and Cl·SO 4 -Na type, which was controlled by rock weathering and evaporation concentration. There was a small amount of calcium and magnesium feldspar dissolved in the upstream groundwater, and the chemical components of the midstream groundwater were mainly the weathering and dissolution of carbonate rocks. The contribution rates of weathering filtration, anthropogenic activities, native sedimentary environment, alternating adsorption of cations, and other factors to the chemical components of surface water and groundwater in the study area were 39.1%, 15.0%, 12.6%, 13.8%, and 19.5%, respectively. The deuterium and oxygen isotope contents of Datong River water showed a trend of enrichment to depletion along the groundwater flow direction. The δ D and δ 18 O isotope test results showed that the deuterium and oxygen isotope content in the Datong River along the groundwater flow showed a trend of enrichment to depletion. The upper and middle reaches of the Datong River were mainly recharged by atmospheric precipitation, whereas the lower reaches were affected by geological structure and influenced by hydrogeological conditions, which was mainly due to diving and spring water overflow to supply river water, as the discharge area of groundwater.

The high concentration of iron and manganese in groundwater is harmful to human health, and the sources of manganese in rapidly urbanization areas are complex. Based on more than 2500 sets of hydrochemical data in different historical periods, the spatial distribution characteristics, sources, and genesis of groundwater manganese in different aquifers and areas with different urbanization levels in the Pearl River Delta were studied by using mathematical statistics and principal component analysis. The results showed that the concentration of manganese in groundwater in the pore aquifer was obviously higher than that in the fissure and karst aquifer. The proportion of high-manganese groundwater in the pore aquifer was twice that in the fissure and karst aquifer. The proportion of high-manganese groundwater in urbanized and suburban areas was significantly higher than that in non-urbanized areas. On a regional scale, the decomposition of organic matter and the reductive dissolution of Fe-Mn (oxygen) hydroxide in sedimentary strata under reductive conditions may have been the main factors controlling the increase in manganese concentration in pore aquifers. High-manganese groundwater in fissured aquifers may have been affected by low-oxygen domestic sewage leakage accompanying urbanization and industrial wastewater leakage and infiltration accompanying industrialization. The pore high-manganese groundwater was controlled by reduction conditions, and the weakly acidic environment of fissure and karst high-manganese groundwater was the important influencing factor. In the past 10 years, the groundwater environment in the study area has been improving, and the increase in groundwater redox potential and pH was not conducive to the formation of high-manganese groundwater, which was also the main cause of the overall decrease in Mn 2+ concentration in groundwater of different types of aquifers in the process of urbanization.

The source of iodine in the groundwater of coastal urbanization areas is complex, and high-iodine groundwater is a potential threat to the safety of drinking water. Based on this, this study took the Pearl River Delta, which is developing rapidly in urbanization, as the research area. Additionally, the occurrence characteristics and driving factors of iodide in shallow groundwater of different aquifers and different urbanization levels in the Pearl River Delta were studied using mathematical statistics, principal component analysis, and other methods. The results showed that the concentration of iodide in the shallow groundwater was 2.34 mg·L -1 and undetected in the form of I - . Among 1567 groundwater samples in the study area, there were 120 groups of groundwater with high iodine content greater than 0.1 mg·L -1 , accounting for 7.7%. Among them, 84 and 36 groups were detected in shallow porous and shallow fissure high-iodine groundwater, respectively, whereas no high-iodine groundwater was detected in the karst aquifer. The proportion of high-iodine groundwater was 8.0% in the shallow porous aquifer and 7.5% in the shallow fissure aquifer. Both the porous aquifer and the fissured aquifer with high iodine content were mainly distributed in the urbanized areas, the proportion of which was more than three times that of the non-urbanized areas. The chemical types of the high-iodine groundwater were mainly HCO 3 ·Cl-Ca·Na and Cl-Na type water, which have the characteristics of high pH and low redox potential. The reduction and dissolution of iodine-containing Fe/Mn (oxygen) hydroxides and the decomposition of iodine-rich organics in sediments may be the main sources of high-iodine groundwater in the shallow porous aquifers of the Pearl River Delta Plain. The degradation and urbanization of organic matter in carbonate-rich rocks is accompanied by the leakage of reducing sewage, which may be the main source of high-iodine groundwater in shallow fissured aquifers. The neutral to weakly alkaline reduction environment with rich organic matter was the main cause of high-iodine groundwater in the Delta Plain area. Weathering, leaching, cation exchange, and sea-land interactions are the main hydrogeochemical processes in the evolution of high-iodine groundwater in the Pearl River Delta.

In response to rapid economic development, nitrate pollution of groundwater is becoming a serious issue in many parts of China. Urbanization and industrialization are the main drivers of NO 3 -type groundwater expansion. Focusing on the Pearl River Delta, the occurrence and driving factors of shallow nitrate groundwater are discussed. Overall, groundwater nitrate concentrations are generally high in this region. Of 1538 groundwater samples, 5.7% had nitrate concentrations higher than the groundwater quality standard(88.6 mg·L -1 ) and 18.5% were classified as NO 3 -type waters, which are mainly distributed in the hilly and piedmont areas. Guangzhou, Dongguan, Foshan, Zhuhai and other areas show high total dissolved solid(TDS)-concentration NO 3 -type waters, which are affected by urbanization and industrialization. In comparison, low-TDS NO 3 -type waters are distributed in the hilly and valley areas. In the Xijiang and Dongjiang plains, the TDS concentrations on groundwater increased significantly due to inputs of industrial wastewater and saline seawater. The NO 3 - concentration in the groundwater in this area exceeded the class III water standard but did not change the hydrochemical type classification. However, industrialization has led to the frequent appearance of SO 4 -type water in this area. The NO 3 -type water occurs in acidic or weakly acidic environments, typically characterized by low TDS and total hardness concentrations, and high Cl - , SO 4 2- , and K + concentrations. The formation of NO 3 -type water is mainly affected by domestic sewage, industrial wastewater, agricultural nitrogen fertilizer, septic tank outflows, and landfill leachate leakage. Generally, the pollution loads of high-TDS NO 3 -type waters are higher than low-TDS NO 3 -type waters. The delineation of NO 3 -type waters, especially the low-TDS type, is helpful for identifying groundwaters posing greater risks for human activities, and those with low nitrate concentrations but potential pollution risk, which is of great significance in the prevention and control of groundwater pollution.

Objective: To establish a nicotine intravenous self-administration rat model, and to examine, with this model, the effects of two flavoring additives, menthol and cineole, on nicotine dependence., Methods: Thirty male Sprague-Dawley (SD) rats were included in the study. After jugular venous catheterization was performed, fixed concentration of nicotine was administered in order to train the rats and establish the rat model of intravenous self-administration groups, receiving intraperitoneal injection of menthol, cineole, and dimethyl sulfoxide (DMSO), the vehicle that was used for the control group. The rats were tested with different fixed-ratio (FR) schedules, including FR1 schedule, in which the rat received one nicotine infusion for every active nose poke, FR2 schedule, in which the rat received one nicotine infusion for every two active nose pokes, and FR5 schedule, in which the rat received one nicotine infusion for every five active nose pokes. The number of active and inactive poke responses and the number of nicotine infusion were documented accordingly., Results: After 10 days of training in nicotine self-administration, the 30 rats demonstrated significant increase in the number of active poke responses and the number of nicotine infusion, which were maintained at a stable and relatively high level. The number of active poke responses was significantly higher that of inactive poke responses ( P < 0.001). The rat model of intravenous nicotine self-administration was successfully established. In the testing phase, under the FR2 schedule, the menthol group showed a reduced number of active poke responses ( P =0.020). Under the FR5 schedule, the groups showed obvious interaction between time and the number of active poke responses ( P <0.011), with the menthol group showing reduced number of active poke responses on day three ( P =0.011) and the cineole group showing rising number of active poke responses on day three ( P =0.003). The DMSO control group did not show any significant change., Conclusions: Menthol and cineole are shown to have an effect on nicotine dependence. When there is relative difficulty involved in obtaining nicotine, menthol suppresses nicotine dependence, whereas cineole enhances nicotine dependence., (Copyright© by Editorial Board of Journal of Sichuan University (Medical Sciences).)

With the development of the local economy, the volume of groundwater production has increased continuously in the past decades in the Tacheng Basin of the Xinjiang Uygur Automous Region. Previous studies have not provided a clear pattern of the chemical composition evolution of groundwater and its driving force in this basin, which makes the future development and utilization of groundwater riskier. This study carried out systematic sampling and analysis of groundwater chemistry in this basin, and the chemical evolution of groundwater in the basin was analyzed by comparison with historical hydrochemical data. The results show that Ca 2+ and Na + are the main cations in the groundwater, HCO 3 - , SO 4 2- are the main anions in the groundwater, and freshwater is widely distributed. The chemical types of groundwater changed from HCO 3 -Ca and HCO 3 ·SO 4 -Ca·Mg in the source zone in front of the mountains to SO 4 ·HCO 3 -Na·Ca type in the plain area. In comparison with the hydrochemical data of 1979, HCO 3 and SO 4 ·HCO 3 type groundwater increased significantly. SO 4 and Cl type groundwater with high total dissolved solids decreased significantly. However, the Cl - and SO 4 2- concentration and total hardness in the groundwater around the cities and towns increased. Aquifer material and the change of flowing field are the two controlling factors of groundwater chemical change, but the leakage of waste water from city drainage channels also affects the groundwater chemistry drastically.

The three-dimensional coordination polymer poly[[bis(μ₃-2-aminoacetato)di-μ-aqua-μ₃-(naphthalene-1,5-disulfonato)-hexasilver(I)] dihydrate], {[Ag₆(C₁₀H₆O₆S₂)(C₂H₄NO₂)₄(H₂O)₂]·2H₂O}n, based on mixed naphthalene-1,5-disulfonate (L1) and 2-aminoacetate (L2) ligands, contains two Ag(I) centres (Ag1 and Ag4) in general positions, and another two (Ag2 and Ag3) on inversion centres. Ag1 is five-coordinated by three O atoms from one L1 anion, one L2 anion and one water molecule, one N atom from one L2 anion and one AgI cation in a distorted trigonal-bipyramidal coordination geometry. Ag2 is surrounded by four O atoms from two L2 anions and two water molecules, and two AgI cations in a slightly octahedral coordination geometry. Ag3 is four-coordinated by two O atoms from two L2 anions and two AgI cations in a slightly distorted square geometry, while Ag4 is also four-coordinated by two O atoms from one L1 and one L2 ligand, one N atom from another L2 anion, and one AgI cation, exhibiting a distorted tetrahedral coordination geometry. In the crystal structure, there are two one-dimensional chains nearly perpendicular to one another (interchain angle = 87.0°). The chains are connected by water molecules to give a two-dimensional layer, and the layers are further bridged by L1 anions to generate a novel three-dimensional framework. Moreover, hydrogen-bonding interactions consolidate the network.