Source Of Ions Research Articles

Spatio-seasonal patterns and sources of major ions in the Longjiang River catchment, Southern China.

River water quality is closely related to the major ion sources and hydrological conditions. However, there is a limited cognition about the geochemical sources and the seasonal variations of major ions. Thus, in this study, a total of 90 water samples were collected from the Longjiang River and its three tributaries in the dry and wet seasons. The samples were analyzed, including major ion concentrations and physicochemical parameters. Statistical analysis, such as correlation analysis and principal component analysis (PCA), was employed to investigate the spatial and seasonal variations in major ion composition and their respective sources. Our study revealed that the predominant major ions in the studied samples are Ca2+, Mg2+, HCO - 3, and SO2 - 4. Most of ions exhibited notable spatial disparities attributable to variations in geological settings and human activities. Regions characterized by igneous rock outcrops tend to exhibit higher levels of K+ and Na+, while areas with higher population densities in the middle and downstream segments show elevated concentrations of Cl-, NO - 3, SO2 - 4, Na+, and K+. The observed peak SO2 - 4 levels may be attributed to active mining operations. Most parameters displayed higher values in flood season than those in dry season due to dilution effects. Stoichiometric analysis indicated that carbonate weathering inputs contribute to over 85% of the mean total cation concentrations in the water, followed by contributions from silicates, atmospheric deposition, and anthropogenic inputs. On the whole, although the water quality remains non-polluted and is suitable for drinking and irrigation purposes, the enrichment of SO2 - 4 and NO - 3 may contribute to water eutrophication. Caution is warranted during the dry season due to reduced water flow resulting from dam interceptions and limited dilution capacity, potentially leading to elevated pollutant concentrations. Taken together, our results provided a scientific basis for water quality managements of monsoon rivers.

Embedded ZnO nanorod in ZIF-8 as a high-efficiency core–shell structural electrocatalyst for subnanomole level sensing of diethylstilbestrol

In view of the core–shell nanocomposites can complement the functions of the core and shell components, we here demonstrate a facile self-template strategy for synthesizing a one-dimensional rod-like hierarchical ZnO@ZIF-8 core–shell structure composed of a stabilized core and an active shell. The ZnO nanorods not only served as the template, but also as source of Zn ions for the in situ formation of zeolitic imidazolate framework-8 (ZIF-8) crystal shell, and the well-stabilized ZnO core preserved its own nature during the growth of the ZIF-8 shell. Furthermore, a sensing platform using ZnO@ZIF-8 as electrocatalyst was developed, which demonstrated salient electrocatalytic activity for diethylstilbestrol (DES) oxidation. The concentration of DES was directly proportional to its anodic peak current in the range of 2 nmol/L to 2 µmol/L, and ultralow detection limit of 0.73 nmol/L ( S/ N = 3) was achieved. The proposed method also gave excellent selectivity, reproducibility, and stability, showing promising analytical performance for the measurement of DES in food samples of animal origin.

Injectable, self-healing hydrogels based on gelatin, quaternized chitosan, and laponite as localized celecoxib delivery system for nucleus pulpous repair

Utilization of injectable hydrogels stands as a paradigm of minimally invasive intervention in the context of intervertebral disc degeneration treatment. Restoration of nucleus pulposus (NP) function exerts a profound influence in alleviating back pain. This study introduces an innovative class of injectable shear-thinning hydrogels, founded on quaternized chitosan (QCS), gelatin (GEL), and laponite (LAP) with the capacity for sustained release of the anti-inflammatory drug, celecoxib (CLX). First, synthesis of Magnesium-Aluminum-Layered double hydroxide (LDH) was achieved through a co-precipitation methodology, as a carrier for celecoxib and a source of Mg ions. Intercalation of celecoxib within LDH layers (LDH-CLX) was verified through a battery of analytical techniques, including FTIR, XRD, SEM, EDAX, TGA and UV–visible spectroscopy confirmed a drug loading efficiency of 39.22 ± 0.09 % within LDH. Then, LDH-CLX was loaded in the optimal GEL-QCS-LAP hydrogel under physiological conditions. Release behavior (15 days profile), mechanical properties, swelling ratio, and degradation rate of the resulting composite were evaluated. A G* of 15–47 kPa was recorded for the hydrogel at 22–40 °C, indicating gel stability in this temperature range. Self-healing properties and injectability of the composite were proved by rheological measurements. Also, ex vivo injection into intervertebral disc of sheep, evidenced in situ forming and NP cavity filling behavior of the hydrogel. Support of GEL-QCS-LAP/LDH-CLX (containing mg2+ ions) for viability and proliferation (from ~94 % on day 1 to ~134 % on day 7) of NP cells proved using MTT assay, DAPI and Live/Dead assays. The hydrogel could significantly upregulate secretion of glycosaminoglycan (GAG, from 4.68 ± 0.1 to 27.54 ± 1.0 μg/ml), when LHD-CLX3% was loaded. We conclude that presence of mg2+ ion and celecoxib in the hydrogel can lead to creation of a suitable environment that encourages GAG secretion. In conclusion, the formulated hydrogel holds promise as a minimally invasive candidate for degenerative disc repair.

Europa Modifies Jupiter's Plasma Sheet

AbstractJupiter's plasma sheet has been understood to be primarily composed of Io‐genic sulfur and oxygen, along with protons at lower mass density. These ions move radially away from Jupiter, filling its magnetosphere. The material in the plasma sheet interacts with Europa, which is also a source of magnetospheric pickup ions, primarily hydrogen and oxygen. Juno's thermal plasma instrument JADE, the Jovian Auroral Distributions Experiment, has provided comprehensive in situ observations of the composition of Jupiter's plasma sheet ions with its Time‐of‐Flight mass‐spectrometry capabilities. Here, we present observations of the magnetospheric composition in the Europa‐Ganymede region of Jupiter's magnetosphere. We find material from Europa is intermittently present at comparable densities to Io‐genic plasma. The intermittency of Europa‐genic signatures suggests Europa's neutral oxygen toroidal cloud is more localized to Europa's vicinity than its hydrogen cloud. These observations reveal a more complex and compositionally diverse magnetosphere than previously thought.

Large-scale kinetic simulations of colliding plasmas within a hohlraum of indirect-drive inertial confinement fusion.

The National Ignition Facility has recently achieved successful burning plasma and ignition using the inertial confinement fusion (ICF) approach. However, there are still many fundamental physics phenomena that are not well understood, including the kinetic processes in the hohlraum. Shan etal. [Phys. Rev. Lett. 120, 195001 (2018)0031-900710.1103/PhysRevLett.120.195001] utilized the energy spectra of neutrons to investigate the kinetic colliding plasma in a hohlraum of indirect drive ICF. However, due to the typical large spatial-temporal scales, this experiment could not be well simulated by using available codes at that time. Utilizing our advanced high-order implicit PIC code, LAPINS, we were able to successfully reproduce the experiment on a large scale of both spatial and temporal dimensions, in which the original computational scale was increased by approximately seven to eight orders of magnitude. Not only is the validity of the explanation of the experiment confirmed by our simulations, i.e., the abnormally large width of neutron spectra comes from beam-target nuclear fusions, but also a different physical insight into the source of energetic deuterium ions is provided. The acceleration of deuterium ions can be categorized into two components: one is propelled by a sheath electric field created by the charge separation at the onset, while the other is a result of the reflection of the potential of the shock wave. The robustness of the acceleration mechanism is analyzed with varying initial conditions, e.g., temperatures, drifting velocity, and ion components. This paper might serve as a reference for benchmark simulations of upcoming simulation codes and may be relevant for future research on mixtures and entropy increments at plasma interfaces.

Acidity-activated degradable Mn-engineered silicon nanohybrids coordinated with iprodione for high-efficiency management of Sclerotinia sclerotiorum and nutrient enhancement to crops

Nanocarriers that respond to environmental stimuli are highly desirable in optimizing the bioavailability of pesticides while minimizing side effects. Manganese-engineered nanomaterials hold promising prospects in agriculture as versatile carriers for both intelligent controlled pesticide delivery and crop nutrient enhancement. Here, Mn-engineered hollow silicon nanospheres (Mn-HSNs) with a bubble-like structure were synthesized for encapsulating iprodione (IPR) to obtain IPR-loaded Mn-HSNs (IPR@Mn-HSNs). Due to its high surface area of 261.28 m2/g and surface-enriched active sites, Mn-HSNs demonstrated a commendable loading capacity of 56.4 % for IPR. Results indicated that the -Si-O-Mn- hybrid framework of IPR@Mn-HSNs not only facilitated acidity-triggered IPR release capability but also served as a plentiful source of Mn ion and orthosilicic acid (Si(OH)4) to promote crop growth. The release amount of IPR in an acidic environment generated by Sclerotinia sclerotiorum of oilseed rape was 3.14 times higher than that under neutral conditions. In vitro experiments demonstrated that the antibacterial activity of IPR@Mn-HSNs was about 1.2 times higher than that of commercial IPR suspension concentrate. Appreciably, IPR@Mn-HSNs could be effectively transported to different parts of rapeseed plants through foliar spray, thereby enhancing the effectiveness of pesticide utilization. More importantly, IPR@Mn-HSNs had no discernible impact on the survival of Harmonia axyridis and were relatively safe for HL-7702 and HK-2 cells. Therefore, this work offers valuable insights into the development of an efficient and environmentally friendly pesticide nanoformulation for sustainable and eco-friendly plant protection in agriculture.

One-step in situ preparation of Zr(Ti)-MOFs on titanium alloys at a low temperature of 80 °C and atmospheric pressure

Preparing metal-organic frameworks (MOFs) film in situ on the surface of the Ti-6Al-4V (TC4) titanium alloy is challenging owing to the dense and stable surface TiO2 passive film. In this study, titanium-doped zirconium-based MOFs (Zr(Ti)-MOFs) film was constructed in situ on the TC4 alloy in one step at a low temperature and atmospheric pressure, with ZrCl4 as the source of Zr metal ions. ZrCl4 attacked and dissolved the TiO2 film to form Zr-O-Ti bonds on the surface of TC4 to provide nucleation sites for further reactions. At the same time, Zr4+ and dissolved Ti4+ combined in solution to form Ti containing Zr-O cluster nodes, which aggregated and grafted to the Zr-O-Ti bonds on the substrate surface, and reacted with organic ligands (terephthalic acid) to form Zr(Ti)-MOFs film. The Ti4+ dissolved from the TC4 participate in the Zr-MOFs formation, thereby changing the high temperature and high-pressure conditions required for the traditional preparation of Zr-MOFs (UiO-66). The in situ preparation of Zr(Ti)-MOFs on TC4 was achieved at 80 °C under atmospheric pressure conditions. This study elucidated the growth mechanism of Zr(Ti)-MOFs on the TC4 surface, providing a reference for the design and In-situ preparation of multifunctional MOFs on the TC4 titanium alloy.

POTENTIAL THREATS TO THE ECOLOGICAL STATE OF WATER IN THE SEVASTOPOL BAY

The purpose of the work is to discuss the main environmental problems of the state of waters in the Sevastopol Bay and to identify the causes affecting their quality. Four seasonal surveys of the Sevastopol Bay water area in 2022 confirmed the prime impact of the Black River runoff, a main source of nutrients, on the hydrochemical composition of the bay waters.At the same time, it is noted that the hydrochemical parameters of the South Bay waters are predominantly affected by freshwater runoff in the estuarine part of the area rather than by the Black River water. It is assumed that the runoff is permanent, and not emergency, as previously thought. With the winds of the southern directions, the spread of the South Bay water to the central part of the Sevastopol Bay is possible, thus affecting the state of its ecosystem.In summer an additional source of ammonium ions was recorded in the estuarine part of the Artillery Bay, next to which the Crystal city beach is located, with concentrations 80 times higher than the background. Since ammonium is a product of organic matter oxidation, its appearance may indicate the predominance of destructive processes, which affect living conditions of biological organisms and, in general, the ecological state of waters. In the warm season a constant deficiency of oxygen was observed in the bottom waters of an artificial depression under the floating dock, which in some cases leads to the formation of hydrogen sulfide. All detected threats affect the ecological state of entire ecosystem of the bay, the living conditions of biological organisms and the recreational potential of the bay

Exploring the Potential of Sr2+ for Improving the Post-Hardening Strength and Durability Characteristics of Cement Paste Composites

This study investigates the effects of strontium ions on enhancing the post-hardening strength and durability characteristics of hydrated cement composites, exploring their potential use as a rehabilitation method for aging concrete structures. A 30% strontium nitrate solution served as the source of strontium ions. Cement paste specimens with a water-to-cement ratio of 0.5, cured for 28 days, were submerged in the 30% strontium nitrate solution to facilitate strontium ion penetration. Compressive and flexural strength tests were conducted on the specimens and compared to those cured in deionized water. Moreover, the durability performance, including surface abrasion resistance, water sorptivity, and porosity, was examined. Scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray diffractometry (XRD) analyses were also carried out to investigate the microscopic morphology and chemical characteristics of the specimens. Results indicated that the strontium-treated specimens exhibited notable enhancements in both compressive and flexural strengths, especially in flexural strength. The specimens also demonstrated improved surface abrasion resistance, decreased water absorption, and a marked reduction in porosity. SEM analysis revealed a densified microstructure in the strontium-treated cement paste specimens, and EDS and XRD analyses showed changes in their morphology and chemical compositions and structures, indicating the formation of new types of hydrates. Accordingly, this study suggests that the strontium ion treatment method has significant potential for the maintenance and restoration of aging cementitious materials.

Influence of industrial effluent treatment ettringite on the compressive and tensile strength and microstructure of soil-cement mixtures

It is increasingly important to find solutions for the problem of the aluminium anodising industry which generates a large amount of acid and alkaline wastewater, composed of high amounts of phosphates, sulphates, nitrates and aluminium. The sulphate removal trough ettringite precipitation is a simple process and involves a low-cost operating. The ettringite can be also formed during the cement hydration in soil-cement mixtures which causes several damages such as expansion. However, the effect of ettringite on the compressive strength, tensile strength and microstructure have few studies. This paper presents a novel experimental study on the influence of the industrial effluent treatment ettringite in resistance and microstructure of soil-cement mixtures. Experimental tests were performed using natural soil, soil mixed with 5% and 6% of cement and soil mixed with 5% and 6% of cement and ettringite for each material. The resistance of the materials was evaluated by unconfined compressive strength and indirect tensile strength, after 3, 7 and 14 days of cure. Additionally, several characterization tests and microstructure analysis were performed. Regarding the experimental results, the compressive strength and tensile strength decreases about 75% and 85%, respectively, when ettringite was added in soil-cement mixtures. The microstructure of natural soil, soil-cement and soil-cement-ettringite mixtures shows that the addition of cement and ettringite, simultaneously, increases the ettringite crystal formation mainly because the cement functions as a source of sulfate ions contributing with the formation of more crystals. Experimental results indicate that the incorporation of ettringite in soil-cement mixtures is not suitable for geotechnical applications.

Investigation on fluorescent sensing properties of Cd(II)-coordination polymers synthesized by nitrogen-containing carboxylic acid ligand

In this study, two-dimensional (2D) cadmium-based coordination polymer (CP) (Cd-1, [Cd4L8]n) and one-dimensional (1D) cadmium-based CP (Cd-2, [CdL(H2O)(NO3)·H2O]n) have been obtained by mixing 1-(4-benzoic acid)-3-(pyrazinyl)-1H-1,2,4-triazole (HL) as organic ligand and CdCO3 as a source of metal ions in hydrothermal/solvent-thermal reaction. The structures and properties of two examples of Cd(II) CPs were characterized and analyzed. The results from infrared spectroscopy, thermogravimetric analysis, and X-ray single-crystal diffraction analysis indicated that the CPs have a stable framework structure and better thermal stability. In addition, in the study of fluorescence properties, two Cd(II)-CPs were found to have high sensitivity to the specific recognition of Fe3+, CrO42− and Cr2O72− ions in metal nitrate and anionic aqueous solutions, and the stability and recyclability of which were further demonstrated through cycling tests, which are expected to be used for the development of the new Cd(II)-CPs and to be an excellent fluorescent probe material.

Evidence the Isc iron–sulfur cluster biogenesis machinery is the source of iron for [NiFe]-cofactor biosynthesis in Escherichia coli

[NiFe]-hydrogenases have a bimetallic NiFe(CN)2CO cofactor in their large, catalytic subunit. The 136 Da Fe(CN)2CO group of this cofactor is preassembled on a distinct HypC–HypD scaffold complex, but the intracellular source of the iron ion is unresolved. Native mass spectrometric analysis of HypCD complexes defined the [4Fe–4S] cluster associated with HypD and identified + 26 to 28 Da and + 136 Da modifications specifically associated with HypC. A HypCC2A variant without the essential conserved N-terminal cysteine residue dissociated from its complex with native HypD lacked all modifications. Native HypC dissociated from HypCD complexes isolated from Escherichia coli strains deleted for the iscS or iscU genes, encoding core components of the Isc iron–sulfur cluster biogenesis machinery, specifically lacked the + 136 Da modification, but this was retained on HypC from suf mutants. The presence or absence of the + 136 Da modification on the HypCD complex correlated with the hydrogenase enzyme activity profiles of the respective mutant strains. Notably, the [4Fe–4S] cluster on HypD was identified in all HypCD complexes analyzed. These results suggest that the iron of the Fe(CN)2CO group on HypCD derives from the Isc machinery, while either the Isc or the Suf machinery can deliver the [4Fe–4S] cluster to HypD.

Relative Humidity Dominances in Negative Air Ion Concentration: Insights from One–Year Measurements of Urban Forests and Natural Forests

Forests are one of the most important sources of negative oxygen ions (NAIs). NAIs have been recognized as beneficial for both physical and mental well–being, and higher concentrations of NAIs have been associated with improved health. However, the environmental factors that predominantly influence NAI concentration and their relationship with NAIs remain uncertain. This study aims to investigate the dominant factors and their impact on NAI concentration by observing NAIs and various environmental factors in two different environments (natural forest and urban forest) in the Beijing region over a one–year period. Through our investigation, we aimed to identify the key factor as well as other influential variables affecting NAI concentration. Our analysis encompassed the examination of dynamic concentration changes over multiple time scales, revealing uniform trends in both forest types. Notably, natural forests consistently demonstrated higher NAI concentration across these time scales, attributable to greater vegetation density and the stability of the forest microenvironment. By utilizing regression, correlation analysis, and structural equation analysis, we determined that relative humidity (RH) has the most significant effect on NAI concentration. Notably, both NAI concentration and RH displayed similar patterns across multiple time scales. When considering hourly average daily variation, the lowest values for both NAI concentration and RH were observed at noon, followed by an increase that persisted throughout the night. Seasonal average variation showed that both NAI concentration and RH peaked in the summer, followed by autumn. In terms of daily average annual variation, summer exhibited more days with high NAI concentration and high RH, which can be attributed to the increased rainfall during that season. Rainy weather was found to contribute to higher NAI concentration and RH levels. Furthermore, our findings revealed that on a daily scale, high RH and high NAI concentration occurred more frequently under conditions of high air temperature and low wind speed. However, the air quality index demonstrated only a minor effect in urban forest, while net radiation exhibited no significant influence on NAI concentration and RH. The fitted equations and trends of the aforementioned environmental factors with NAI concentration and RH were found to be comparable. The path analysis further corroborates these conclusions. The findings of this study indicate that RH is the primary factor driving the fluctuations in NAI concentration across various time scales, including hourly, daily, and seasonal variations. The study revealed that wind speed indirectly impacts NAI concentration by modulating RH. In contrast, air temperature influences NAI concentration both indirectly through RH and directly. The environmental factors affecting NAI concentration in the two types of forests are similar, but the degrees vary; in urban forests, wind speed, air quality index, and RH are slightly higher, while in natural forests, air temperature is slightly higher. This discovery further enhances our understanding of the underlying mechanisms and dynamic changes in NAI concentration within urban forests and natural forests. Moreover, it confirms the reliability and effectiveness of using RH as an indicator to monitor changes in NAI concentration over time.

Preparation of manganese-based metal organic framework (MOF) and its characterization properties

Metal-organic frameworks (MOFs) are produced by the reaction of metal ions and organic linkers with extremely crystalline and porous coordination networks. The applications of MOF cover from gas purification, gas separation, catalysis and super-capacitors. This work reports on the synthesization of metal-organic framework (MOF), using mangan (II) nitrate tetrahydrate as source of metal ions, 2-methylimidazole as organic ligand and ethanol as solvent. The material was prepared using precipitation method, at room temperature for 48 hours. The characterization of this material were carried out including X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The SEM analysis shows an irregular structure with a few petals. XRD shows several peaks, indicating crystallinity of the material, and amorphous state. To study the electrochemical property of the material, Cyclic Voltammetry (CV) was conducted. The cyclic voltammetry result shows peak at 0.23 V, with current output of 0.14 μA, with no changes in peak position as the scanning rate increases from 10 to 100 mV/s.

Assessing wet season water quality and health risks of Chaobai River: impacts of natural weathering and anthropogenic activities in a small urban watershed

ABSTRACT Small urban watersheds are susceptible to external influences, facing increased solute inputs during high-flow periods without sufficient dilution. This study determined the sources of major ions in the Chaobai River, which is the essential surface water source of North China. The dominant river water type was HCO3-Ca·Mg based on the Piper diagram. PCA and ion ratios revealed that natural weathering (evaporate dissolution, carbonate, and silicate weathering by carbonic and sulfuric acid) and anthropogenic activities (urban domestic sewage and industrial effluent) were the dominant factors affecting the chemical composition. Sodium adsorption ratio (SAR), soluble sodium percentage (Na%), and residual sodium carbonate (RSC) assessments indicated potential sodium and moderate salinity hazards. Meanwhile, the non-carcinogenic health risks of riverine solutes evaluated by health risk assessment need to be noticed, particularly for children. The limitation of urban sewage discharge is crucial for improving water quality in urban watershed and needs further studies.

Laser optogalvanic spectroscopy of lead lines — Isotope shifts and hyperfine structure studies

Six atomic lines of Pb I in the 569–612 nm wavelength range and two lines of Pb II in the wavelength range of 560-608 nm were examined using optogalvanic spectroscopy. A hollow cathode discharge lamp was the source of Pb atoms and ions. Hyperfine structure constants were measured for levels associated with the observed transitions. The result of the research was also the determination of isotope shifts in the studied lines. The experimental data we have obtained complement or correct the existing database. We determined six values of the A constants of the hyperfine structure of Pb I, including one value determined for the first time and clarified one value of the A constant for Pb II. We determined seven new values of isotopic shifts between individual isotopes for two Pb I lines and one Pb II line. Furthermore, ab-initio MCDHF calculations of the observed isotope shifts and hyperfine structure constants were performed. Theoretical results are in good agreement with experimental data.

Heap sulphuric-thiocyanate leaching of gold and uranium

The article evaluates the main parameters of simultaneous heap leaching of gold and uranium from oxidised gold-uranium ore using sulphuric acid thiocyanate solutions. Pilot tests for the simultaneous heap leaching of gold and uranium were carried out using oxidised crushed gold-uranium ore with a size of -40+0 mm. The gold and uranium content in the ore was 0.80 and 266 g/t, respectively. Experiments were carried out using a percolation column with a diameter of 300 mm and a height of 2000 mm The ore mass in the column was 180 kg. The temperature during the tests was in the range of 17–25°C. Leaching was carried out under the following conditions: H2SO4 concentration – 5 g/dm3, SCN– concentration – 0.5 g/dm3, Eh – 490–510 mV, Fe3+ ion concentration – 1.0–1.5 g/dm3. Acid-soluble minerals contained in the ore comprised the source of iron ions. Hydrogen peroxide was used to oxidise Fe2+ ions. Pilot tests were carried out in a closed cycle with separate sorption of gold and uranium. Based on the research results, gold recovery reached 90%, while uranium recovery was 55%. Following gold and uranium leaching, the loaded activated carbons and ion exchange resins were obtained. It was established that the gold content on activated carbons was 0.5–0.6 mg/g, while the uranium content on ion exchange resins amounted to 30–35 mg/g. The reagent consumption was as follows: H2SO4 – 10.5 kg/t, KSCN – 0.94 kg/t, H2O2 – 0.65 kg/t. It is shown that the technology for simultaneous heap leaching of gold and uranium with sulphuric acid thiocyanate solutions offers efficient processing of the ore. The recovery rates of gold and uranium are comparable to those obtained during pilot tests for heap leaching of the ore using conventional technology, involving the individual twostage leaching of these metals using sulphuric acid and cyanide solutions.

Controlling Factors of Groundwater Salinization and Pollution in the Oasis Zone of the Cherchen River Basin of Xinjiang

Groundwater is a vital resource for local human life and production in the oasis zone of the Cherchen River Basin of Xinjiang. Understanding the controlling factors of groundwater salinization and pollution is of great significance for the sustainable utilization of groundwater resources and protection of the ecological environment in desert oasis areas. In light of this, a total of 36 single structure unconfined groundwater samples and 54 multi-layered structure unconfined and confined groundwater samples were collected from the oasis zone of the Cherchen River Basin and evaluated for the distribution characteristics and pollution status of major ions. Hydrogeochemical methods (e.g., Piper diagram, multivariate statistics, Gibbs model, and relationships among ions) were used to determine the main controlling factors of groundwater salinization and pollution. Differences in hydrogeochemical zonation were found from the single structure unconfined aquifers in sloping plains of piedmont areas to the multi-layered structure unconfined and confined aquifers in alluvial-proluvial plain areas, and Cl-Na (87.8%) was the main hydrochemical type in the groundwater of the study area. The quality of single structure unconfined groundwater was starkly better than that of the multi-layered unconfined and confined groundwater, which was mainly caused by Na+ (mean value of 9 969 mg·L-1), Cl- (13 687 mg·L-1), and SO42- (5 840 mg·L-1). Moreover, the natural hydrogeochemical process was the main reason for the deterioration of groundwater quality. The hydrochemistry was mainly controlled by the water-rock interaction and evaporation processes. The mineral dissolution of silicates and evaporites was an important source of chemical ions in the groundwater. Furthermore, the chemical weathering of evaporites combined with the processes of evaporation and cation exchange had a significant influence on the salinization of multi-layered unconfined and confined groundwater in alluvial-proluvial plain areas. In addition, synthetic fertilizers were the main pollution sources of NO3- in groundwater in the intensive agricultural zones.

The Experimental Setup for the Study of Sources of Positive and Negative Ions

The Experimental Setup for the Study of Sources of Positive and Negative Ions

Electrosynthesis and Characterizations of Aluminum Silver Selenide (Alagse2), Thin Films for Possible Device Applications

The semiconductor thin films of Aluminum Silver selenide (AlAgSe2) have been successfully deposited onto FTO glass substrate using electrodeposition method. AgNO3, AlCl3.6H2O and Selenium powder were the precursors used for sources of Ag, Al and Se ions respectively. Prototype of the films were again made and subjected to annealing at temperature of 150°C for 5 minutes to remove the element of moisture content in the as deposited films. The properties of the films such as optical, structural and compositional were investigated using UV-VIS Spectrophotometry, X-ray diffractometry and Rutherford Backscattering Spectroscopy (RBS) analysis respectively to determine the possible areas of applications of the films. Optical analysis revealed that the films have high absorbance in the UV region but decreased in the visible and near infrared regions. The increase in the concentration of selenide ions however decrease the absorbance of the films but annealing tends to increases the absorbance. The films also exhibited very high values of refractive index with minimum value in the order of 2.0 for both the annealed and as deposited samples. The bandgap energies of the films were found to be 1.7 eV, 1.8 eV, 2.2 eV, 2.8 eV and 2.9 eV for as deposited, but decreased to the values of 1.5 eV, 1.6 eV, 1.92 eV, 2.15 eV and 2.5 eV after annealing for the films deposited with 0.1 M, 0.2 M, 0.3 M, 0.4 M and 0.5 M Se ions respectively. The structural analysis indicates that AlAgSe2 films are crystalline in nature with most preferential crystalline plane of (112). The RBS compositional analysis showed that the deposited thin films are rich in silver content. These properties exhibited by the deposited thin films of AlAgSe2 are desirable for photovoltaic devices and for many other optical and optoelectronic applications.