A novel colorimetric fluorescent probe for detecting hydrazine in living cells and zebrafish.

Hydrazine (NH2 NH2 ) is a highly toxic organic substance that poses a threat to human health. Monitoring hydrazine with high sensitivity and selectivity is very important. Here, a simple colorimetric fluorescent probe for hydrazine detection, which is a seminaphthorhodafluor derivative containing thiophene-2-carboxylic acid ester reaction site, was rationally constructed. The probe itself exhibits weak fluorescence. The fluorescence is significantly enhanced when hydrazine is added. The probe exhibited a broad linear range (0-1 mM) with satisfactory selectivity and sensitivity (limit of detection 36.4 µM), which turned out to be an excellent fluorescent probe for monitoring hydrazine. Additionally, the probe was used to track hydrazine in living cells and zebrafish with great success, and the detection performance was satisfying. These results proved that this type of fluorescent probe with the thiophene-2-carboxylic acid ester structure can detect hydrazine with higher selectivity and sensitivity.

Groundwater hydrogeochemical formation and evolution in a karst aquifer system affected by anthropogenic impacts.

Karst groundwater, an important water source, is often highly influenced by human impacts, causing environmental damage and threats to human health. However, studies on the anthropogenic influences on the hydrogeochemical evolution of karst groundwater are relatively rare. To assess hydrogeochemical formation and evolution, we focused on a typical karst groundwater system (Jinan, China) which is composed of cold groundwater (av. temperature 13-17 °C), springs and geothermal water (av. temperature > 30 °C) and is significantly affected by human activities. The study was performed by means of water samples collecting and analyzing and isotope analysis (2H, 18O and 14C). The statistical analysis and inverse models were also applied to further understand geochemical processes and anthropogenic influences. The 2H, 18O and 14C results indicate that the cold karst groundwater is easily influenced and contaminated by the local environment, while geothermal water is relatively old with a slow rate of recharge. The hydrochemical types of cold karst groundwater are mainly HCO3-Ca and HCO3·SO4-Ca, while geothermal water hydrochemical types are SO4-Ca·Na and SO4-Ca. Groundwater Ca2+, Mg2+, HCO3- and SO42- are mainly controlled by carbonate equilibrium, gypsum dissolution and dedolomitization. Groundwater Na+, K+ and Cl- are mainly derived from halite dissolution, and in geothermal water, they are also affected by incongruent dissolution of albite and K-feldspar. Anthropogenic nitrogen produces ammonium resulting in nitrification and reduction in CO2(g) consumption and HCO3- release from carbonate dissolution. Principal component analysis and inverse models also indicate that nitrification and denitrification have significantly affected water-rock interactions. Our study suggests that karst groundwater quality is dominated by water-rock interactions and elucidates the influence of anthropogenic nitrogen. We believe that this paper will be a good reference point to study anthropogenic influences on the groundwater environment and to protect karst groundwater globally.

A highly selective colorimetric and fluorescent dual-modal probe for the rapid determination of fluoride anions.

In this work, 4-(p-hydroxybenzylidenehydrazino)-N-butyl-1,8-naphthalimide (1) has been designed and synthesized as a colorimetric and fluorescent dual-modal probe for F- . Compound 1 immediately detected inorganic fluoride salts using UV/vis absorption and fluorescence spectroscopy methods, and served as a 'naked-eye' indicator for F- with high selectivity and sensitivity. Both the absorption and fluorescence spectra show excellent linearity with the concentration of F- . Real-life applications demonstrated that our proposed analytical system provided a satisfactory method for the determination of F- . In addition, the reaction mechanism of deprotonation was confirmed by 1 H NMR.

Effect of egg freshness on texture and baking characteristics of batter systems formulated using egg, flour and sugar.

BACKGROUND: The aim of this work was to evaluate the effects of egg freshness on baking properties and final qualities in batter systems. Batters were made with eggs of different freshness, and the properties of batter systems were studied through rheological analysis, rapid viscosity analysis (RVA), differential scanning calorimetry (DSC), batter density and expansion rate during the baking and cooling processes. Moreover, the qualities of final baked systems were investigated, including specific volume and texture profile analysis (TPA). RESULTS: The flow behavior of batters showed that the consistency index (K) decreased as the Haugh unit (HU) value decreased, while the flow behavior index (n) increased. Both the storage modulus (G') and loss modulus (G″) determined by mechanical spectra at 20 °C decreased with decreasing HU. RVA and DSC determinations revealed that lower-HU samples had a lower viscosity in the baking process and a shorter time for starch gelatinization and egg protein denaturation. Observation of the batter density revealed an increasing change, which was reflected by a decrease in the specific volume of final models. TPA showed significant differences in hardness and chewiness, but no significant differences in springiness and cohesiveness were found. CONCLUSION: The egg freshness affected the properties of batter systems.

Numerical simulation and protection of the dynamic change of Jinan karst spring based on coupling of seepage and conduit flow.

The objective of this study was to predict the dynamic change in the spring water level more precisely, to provide timely solutions for karst spring protection. Using the Jinan spring region as a case study, this study established a numerical model of a karst groundwater system, and optimized the mining layout. The calculated maximum extraction volume following the optimized exploitation layout was 0.69 m3/s, in order to ensure the continuous flow of spring water in the median water year. A coupled karst groundwater numerical model with dual structure was developed using the MODFLOW-Conduit Flow Process (CFP), which simulates and then precisely predicts changes in the water level of the karst springs. Here, the plane extension direction of the karst conduit was determined by a tracer test and correlation analysis of the spring water levels and groundwater levels of the observation wells. Meanwhile, the vertical location of the karst conduit was determined by layered monitoring of the groundwater temperature and conductivity. Based on this, a coupling model of seepage and conduit flow was created to simulate the dynamic change in the spring water level, and the dual-media coupling model improved the simulation accuracy of the spring water level. The current study confirmed that, compared to the porous media seepage model, the dual-media coupling model can simulate the groundwater level dynamic change more accurately in a heterogeneous karst aquifer in northern China. The coupling model was used to analyze the effect of supplementation and optimize mining, to ensure that spring water continues to flow during the dry season while supplying the mining demand.

Modeling the effects of temperature on the migration and transformation of nitrate during riverbank filtration using HYDRUS-2D.

Riverbank filtration is a natural aquifer-based process. The nitrogen dynamics in a riverbank filtration system are affected by many factors, including temperature, water quality, and travel time, which cannot be quantified easily. In this study, a field experiment was conducted to investigate nitrogen transport during riverbank filtration. The HYDRUS-2D software package was used to investigate and quantify the factors that affect the fate of nitrogen. The effects of temperature, water quality, and travel time on nitrate transport were considered. The model was calibrated and validated using field experimental data from the river water and groundwater during riverbank filtration at different periods. The results showed that HYDRUS-2D adequately simulated nitrate transport during riverbank filtration. The denitrification rate constant exhibited a positive exponential relationship with temperature. An empirical formula describing this relationship in riverbank filtration was developed and validated. In addition, the denitrification rate can be quantified within a specified temperature data range under field conditions. Compared with indoor experimental conditions, for the same temperature, there was a 10-fold increase in the denitrification rate constant under field conditions. The results showed that most of the nitrate removal occurred in the riparian zone at high temperatures during riverbank filtration. We concluded that the fate of nitrate in the riparian zone is strongly controlled by groundwater temperature. Travel time also plays an important role in nitrate removal during riverbank filtration.

Research Progress in Membrane Lipid Metabolism and Molecular Mechanism in Peanut Cold Tolerance.

Early sowing has been extensively used in high-latitude areas to avoid drought stress during sowing; however, cold damage has become the key limiting factor of early sowing. To relieve cold stress, plants develop a series of physiological and biochemical changes and sophisticated molecular regulatory mechanisms. The biomembrane is the barrier that protects cells from injury as well as the primary place for sensing cold signals. Chilling tolerance is closely related to the composition, structure, and metabolic process of membrane lipids. This review focuses on membrane lipid metabolism and its molecular mechanism, as well as lipid signal transduction in peanut (Arachis hypogaea L.) under cold stress to build a foundation for explicating lipid metabolism regulation patterns and physiological and molecular response mechanisms during cold stress and to promote the genetic improvement of peanut cold tolerance.

The Blocking Effect of Clay in Groundwater Systems: A Case Study in an Inland Plain Area.

In order to increase understanding of the hydrogeochemical effects that influence changes in the quality of salt water, we investigated the distribution of saline and fresh water in an inland plain area and, in particular, the scarcity of fresh water resources. Taking the inland plain in Jiyang County as a specific case study, samples of undisturbed clay and underground saline water from different depths were collected to examine hydrogeological changes. A wide variety of methods was used to analyze the blocking effect of clay on the chemical characteristics of the groundwater. These include real-time monitoring for field water quality, tests for isothermal adsorption, a factor analysis model, physiochemical analysis, and correlation analysis. Our results show that the optimal adsorption isotherm of clay for Na⁺, Ca2+ and Mg2+ in groundwater conform to the established Henry and Langmuir equations for adsorption isotherms. The influence of clay mineral types and content on the blockage of Na⁺, Ca2+ and Mg2+ in groundwater samples were evident at different depths, with the clay adsorption capacity increasing in line with increases in the clay mineral content. Clay at different depths was found to have the strongest blocking effect on Na⁺ in groundwater, being systematically greater than its effect on Ca2+ and Mg2+. It is believed that the blocking effect of clay has an important influence on the hydrochemical zoning of groundwater in inland plains and the formation of saline water in groundwater systems. This study therefore provides concrete evidence in support of this supposed effect.

Parallel Processing Transport Model MT3DMS by Using OpenMP.

Solute transport modeling resolves advection, dispersion, and chemical reactions in groundwater systems with its accuracy depending on the resolution of domain at all scales, thus the computational efficiency of a simulator becomes a bottleneck for the wide application of numerical simulations. However, the traditional serial numerical simulators have reached their limits for the prohibitive computational time and memory requirement in solving large-scale problems. These limitations have greatly hindered the wide application of groundwater solute transport modeling. Thus, the development of an efficient method for handling large-scale groundwater solute transport simulation is urgently required. In this study, we developed and assessed a parallelized MT3DMS (Modular Three-Dimensional Multispecies Transport Model) by using OpenMP (Open specifications for Multi-Processing) to accelerate the solute transport simulation process. The parallelization was achieved by adding OpenMP compile directives (i.e., defining various types of parallel regions) into the most time-consuming packages, including the Advection package (ADV), Dispersion package (DSP), and Generalized Conjugate Gradient Solver package (GCG). This allows parallel processing on shared-memory multiprocessors, i.e., both the memory requirement and computing efforts are automatically distributed among all processors. Moreover, we discussed two different parallelization strategies for handling numerical models with either many layers or few layers. The performance of parallelized MT3DMS was assessed by two benchmark numerical models with different model domain sizes via a workstation with two quad-core processors. Results showed that the running time of parallelized MT3DMS can be 4.15 times faster than that using sequential MT3DMS. The effects of using different preconditioners (procedures that transform a given problem into a form that is more suitable for numerical solving methods) in the GCG package were additionally evaluated. The modified strategy for handling numerical models with few layers also achieved satisfactory results with running time two times faster than that via sequential simulation. Thus, the proposed parallelization allows high-resolution groundwater transport simulation with higher efficiency for large-scale or multimillion-cell simulation problems.

[Variation of air pollution in new Tangshan industrial area during winter heating period].

To illuminate the air pollution situation of the new Tangshan industrial area in the heating period, the observation of atmospheric pollutants was conducted in Tangshan City, Qianan City and Caofeidian Town from Oct. 2009 to Apr. 2010. The result showed that air pollution was serious in the area in winter. The regional mean concentration of NO, NO2, SO2, CO, PM2.5 and PM10 reached (26 +/- 28), (52 +/- 27), (72 +/- 53), (3 500 +/- 3 600), (82 +/- 65), (164 +/- 121) microg x m(-3) in the heating period, respectively. The concentration of NO and SO2 was 2.5 times in the heating period more than in the non-heating period. The concentration of NO2 and PM10 increased by -30%. The rates that CO and PM10 exceeded the National Ambient Air Quality Standard II were 27% and 40%; and the rate that PM2.5 exceeded the WHO IT1 Standard was 38%. The typical diurnal variations of NO, NO2, SO2, PM2.5 and PM10 were similar with peaking at 08:00 and 18:00, but the diurnal variation of CO was single peak at 08:00 with accumulating in evening. The peaks of NO, CO and SO2 were very high in morning because of the rush hours and the heating, which were 50, 90, and 5100 microg x m(-3), respectively. The peaks of NO2, PM2.5 and PM10 were relatively gentle, which were 56, 105, and 202 microg x m(-3), respectively. The cluster analysis of backward trajectories showed only the northerwinds, the cold airs can wash away the air pollution, while the southerwinds and easternwinds can easily accumulate the pollutants or transport the pollutants to the Beijing-Tianjin region.