In situ DRIFTS study of hygroscopic behavior of mineral aerosol

In situ diffusion reflectance infrared Fourier transform spectroscopy was used to study the water adsorption on mineral oxides （SiO2, a-Al2O3, MgO, Fe2O3, TiO2）. The results showed that all the water adsorption isotherms were well fitted with the Brunauer-Emmett-Teller （BET）-Ⅲ type equation, with the calculated monolayers occurring at 24%-30% relative humidity. It showed that about 1-5 layers of water adsorbed on oxides surfaces in ambient relative humidity （20%-90%）. The measured deliquescence relative humidity of NaCl was （74 ± 1）%, which demonstrated that DRIFTS is a useful method for the study the hygroscopic behavior of mineral dust. In addition, the limits of DRIPTS were also discussed.

Spatial Heterogeneity of Soil Mineral Oxide Components in Depression Between Karst Hills,Southwest China

In karst regions,the spatial heterogeneity of soil mineral oxides and environmental variables is still not clear.We investigated the spatial heterogeneity of SiO2,Al2O3,Fe2O3,CaO,MgO,P2O5,K2O,and MnO contents in the soils of slope land,plantation forest,secondary forest,and primary forest,as well as their relationships with environmental variables in a karst region of Southwest China.Geostatistics,principal component analysis(PCA),and canonical correlation analysis(CCA)were applied to analyze the field data.The results show that SiO2was the predominant mineral in the soils(45.02%–67.33%),followed by Al2O3and Fe2O3.Most soil mineral oxide components had a strong spatial dependence,except for CaO,MgO,and P2O5in the plantation forest,MgO and P2O5in the secondary forest,and CaO in the slope land.Dimensionality reduction in PCA was not appropriate due to the strong spatial heterogeneity in the ecosystems.Soil mineral oxide components,the main factors in all ecosystems,had greater influences on vegetation than those of conventional soil properties.There were close relationships between soil mineral oxide components and vegetation,topography,and conventional soil properties.Mineral oxide components affected species diversity,organic matter and nitrogen levels.

Typical roles of metal ions in mineral flotation:A review

In flotation,metal ions possess significant roles that are usually fulfilled by either selectively activating or depressing the target minerals.Despite that tremendous efforts have been made to address the roles of metal ions in flotation,it still lacks a comprehensive review,especially to compare various ions instead of focusing on a specific one.This review begins by elaborately categorizing the factors involved in affecting the roles of metal ions in flotation.After that,well-accepted mechanisms are updated and discussed from the ore type.Furthermore,typical approaches to explore the underlying mechanisms are emphasized,including traditional techniques such as micro-flotation,contact angle measurement,zeta potential measurement,and other recent prevailing methodologies,like computational method,solution chemistry calculation,and cyclic voltammetry.This work will pave the way to promote flotations via activities like selectively adding/reducing metal ions,choosing reagents,and regulating the slurry chemistry.

Mineralogy of Manganese Oxide Minerals in Iron Manganese Nodules of Several Main Soils in China

X-ray diffraction and selective chemical dissolution methods were used to investigate the composition of Mn oxide minerals in Fe-Mn nodules of several main types of soils in China. The changes of relative intensity of X-ray diffraction patterns were studied both before and after chemically selective dissolution. It was found that lithiophorite was a common Mn oxide in all examined Fe-Mn nodules. Todorokite, however, was a predominant Mn oxide in Fe-Mn nodules in caf-aquic Vertisols of Linyi, Shandong Province. The Fe-Mn nodules of arp-udic Luvisols in Wuhan and Zaoyang, Hubei Province, contained birnessite and vernadite. Hollandite was found in Fe-Mn nodules of alt-udic Ferrisols of Yizhang, Hunan Province; arp-udic Luvisols of Zaoyang, Hubei Province; and cal-aquic Vertisols of Linyi, Shandong Province. The Fe-Mn nodules in alt-udic Ferrisols of Guiyang, Hunan Province, had a few coronadites. Mineralogy of Mn oxide minerals in soil Fe-Mn nodules was related to soil environment, soil types and quantities of relevant cations.

Flotation of copper oxide minerals:A review

Copper oxide minerals are important copper resources,which include malachite,azurite,chrysocolla,cuprite,etc.Flotation is the most widely used method for the enrichment of copper oxide minerals in the mineral processing industry.In this paper,the surface properties of copper oxide minerals and their effects on the mineral flotation behavior are systematically summarized.The flotation methods of copper oxide minerals and the interaction mechanism with reagents are reviewed in detail.Flotation methods include direct flotation(using chelating reagents or a fatty acid as collector),sulfidization flotation(using xanthate as collector),and activation flotation(using chelating reagents,ammonium/amine salts,metal ions,and oxidant for activation).An effective way to realize efficient flotation of copper oxide minerals is to increase active sites on the surface of copper oxide minerals to enhance the interaction of collector with the mineral surface.Besides,various perspectives for further investigation on the efficient recovery of copper oxide minerals are proposed.

Provenance Study of Fe–Ti Oxide Minerals in the Quaternary Sediments in Yichang Area and Its Implication of Formation Time of the Yangtze Three Gorges, China

The Three Gorges are considered to be critical to understand the formation of Yangtze River. Recent research results suggest that the Yangtze Three Gorges was created during the Quaternary but the exact time is debatable. Fe-Ti oxide minerals are seldom used to study sediment provenance, expecially using scanning electron microscopy （SEM）, and energy dispersive spectrometer （EDS）. In this study, the provenance of Quaternary sediments in Yichang area, which is located to the east of the Yangtze Three Gorges, was investigated by using SEM and EDS to research Fe-Ti oxides. The Panzhihua vanadium titanomagnetite and Emeishan basalt outcrop are located to the west of the Three Gorges. Further, the materials from them are observed in the Quaternary sediments of Yichang area. Fe-Ti oxide minerals from the Huangling granite are observed in the Yunchi and Shanxiyao Formations, which were formed before 0.75 Ma B.P., whereas Fe-Ti oxide minerals from the Huangling granite, Panzhihua vanadium titanomagnetite, and Emeishan basalt are observed in the riverbed and fifth-terrace sediments of the Yangtze River, which were formed after 0.73 Ma B.P.. Thus, we can infer that the Three Gorges formed after the deposition of the Shanxi Formation and before the fifth-terrace; i.e., 0.75-0.73 Ma B.P..

Oxidation of As^Ⅲ by Several Manganese Oxide Minerals in Absence and Presence of Goethite

Oxidation of As^Ⅲ by three types of manganese oxide minerals affected by goethite was investigated by chemical analysis, equilibrium redox, X-ray diffraction （XRD） and transmission electron microscopy （TEM）. Three synthesized Mn oxide minerals of different types, birnessite, todorokite, and hausmannite, could actively oxidize As^Ⅲ to Asv, and greatly varied in their oxidation ability. Layer structured birnessite exhibited the highest capacity of As^Ⅲ oxidation, followed by the tunnel structured todorokite. Lower oxide hansmannite possessed much low capacity of As^Ⅲ oxidation, and released more Mn^2＋ than birnessite and todorokite during the oxidation. The maximum amount of Asv produced during the oxidation of As^Ⅲ by Mn oxide minerals was in the order： birnessite （480.4 mmol/kg） 〉 todorokite （279.6 mmol/kg） 〉 hansmannite （117.9 mmol/kg）. The oxidation capacity of the Mn oxide minerals was found to be relative to the composition, crystallinity, and surface properties. In the presence of goethite oxidation of As^Ⅲ by Mn oxide minerals increased, with maximum amounts of Asv being 651.0 mmol/kg for birnessite, 332.3 mmol/kg for todorokite and 159.4 mmol/kg for hansmannite. Goethite promoted As^Ⅲ oxidation on the surface of Mn oxide minerals through adsorption of the Asv produced, incurring the decrease of Asv concentration in solutions. Thus, the combined effects of the oxidation （by Mn oxide minerals）-adsorption （by goethite） lead to rapid oxidation and immobilization of As in soils and sediments and alleviation of the As^Ⅲ toxicity in the environments.

Bioleaching of a kind of alkaline mixed copper oxide and sulphide mineral

We conducted two-stage acidification-bioleaching experiments to probe the feasibility of bioleaching for a kind of mixed alkaline copper oxide and sulphide mineral. We used the uniform design method for data analysis and experimental optimization, with initial pH value, pulp density, inoculation of bacteria and ferrous iron concentration selected as the influential factors. Polynomial regression shows that the four factors sequentially influence the copper recovery by 14.430%, 8.555%, 1.982% and 3.895%. Acid equilibrium in the bioleaching system is mainly influenced by alkaline gangue content, chemical reactions and bacterial activity. A maximal portion of refractory copper extracted reaches 71.08%. The dynamic analysis of copper recovery indicates that bioleaching goes through a lag leaching phase, prime leaching phase and leaching stationary phase corresponding to the growth phases of bacteria. Compared with the predicted value of 80.87%, the confirmatory experiment observes a 78.21% copper recovery under the optimal conditions of pH of 1.5, pulp density of 5%, bacteria inoculation of 30% and initial ferrous iron concentration of 9 g L-1. Results suggest that bioleaching is technically feasible to improving total copper recovery.

Advance in Matrix Effect Study of LA-MC-ICPMS U-Pb Dating on U-Bearing Oxide Minerals

Objective With the development of analytic technologies, in-situ dating on U-bearing oxide minerals （e.g., cassiterite, rutile and baddeleyite） has been widely used in geological chronological researches and has attracted remarkable attention to explore evolution of the earth and obtain age information of various geological processes. Matrix effect related studies are especially important during in-situ U- Pb dating based on Laser Ablation Multiple Collector Inductively Coupled Plasma Mass Spectrometry （LA-MC- ICPMS）. However, to our knowledge, only few thorough and systematical matrix effect study of U-bearing oxide minerals has been reported. In this study, we systematically analyzed the matrix effect of U-bearing oxide minerals in order to take place the standards which are difficult to prepare with available standards.

Antioxidant capacity and concentration of redox-active trace mineral in fully weaned intra-uterine growth retardation piglets

Background： The redox status of intra-uterine growth retardation（IUGR） piglets post-weaning has been poorly studied.Methods： Newborns from twenty-four sows were weighted, weaned at 21 d and fed a starter diet until sampling.Sampling was done at 14 d post-weaning. A piglet was defined as IUGR when its birth weight was 2 SD below the mean birth weight of the total population. At weaning, eighteen piglets with nearly equal body weight from each category（i.e. IUGR or normal birth weight（NBW） piglets） were selected and then allocated to two treatments,consisted of six replicates with each pen having three piglets.Results： Compared with NBW group, IUGR significantly decreased average daily gain（P 〈 0.001）, average daily feed intake（P = 0.003）, and feed efficiency（P 〈 0.001） of piglets during the first two weeks post-weaning. IUGR decreased the activities of total antioxidant capacity（P = 0.019）, total superoxide dismutase（T-SOD, P = 0.023）,and ceruloplasmin（P = 0.044） but increased the levels of malondialdehyde（P = 0.040） and protein carbonyl（P = 0.010） in plasma. Similarly, the decreased activities of T-SOD（P = 0.005）, copper- and zinc-containing superoxide dismutase（Cu/Zn-SOD, P = 0.002）, and catalase（P = 0.049） was observed in the liver of IUGR piglets than these of NBW piglets. IUGR decreased hepatic Cu/Zn-SOD activity（P = 0.023） per unit of Cu/Zn-SOD protein in piglets when compared with NBW piglets. In addition, IUGR piglets exhibited the decreases in accumulation of copper in both plasma（P = 0.001） and liver（P = 0.014）, as well as the concentrations of iron（P = 0.002） and zinc（P = 0.048） in liver. Compared with NBW, IUGR down-regulated m RNA expression of Cu/Zn-SOD（P = 0.021） in the liver of piglets.Conclusions： The results indicated that IUGR impaired antioxidant capacity and resulted in oxidative damage in fully weaned piglets, which might be associated with the decreased levels of redox-active trace minerals. This study highlights the importance of redox status in IUGR offspring and provides a rationale for alleviating oxidative damage by dietary interventions aiming to supplement trace minerals and to restore redox balance in the future.

Study on Oxygen Isotope Fractionation in RE Oxide Minerals

The oxygen isotope fractionation equations are calculated for major rare earth oxide minerals by using an increment model. The effects of the variation of RE composition, the isomorphic replacement of Ti 4+ , Nb 5+ , Ta 5+ , and Th 4+ and the metamictization on the oxygen isotope fractionation in minerals are also discussed. The rare earth oxides are not applicable for geothermometry due to their changeable oxygen isotope fractionation coefficients.

Preliminary Study of the Characteristics and Genesis of Arsenate Minerals in the Oxidized Zone of the Debao Skarn-Type Cu-Sn Ore Deposit in Guangxi

Through the study of the oxidized zone of the Debao skarn-type Cu-Sn deposit in Guangxi, the authorshave found 14 arsenate minerals, most of which are for the first time reported in China. They are mainly Cuarsenate minerals with subordinate Cu-Pb arsenate minerals and minor Fe-Pb-Ba varieties. Based on their paragenesis these minerals may be divided into the following series: (1) the clinoclasite-olivenite-cornwallite- cornubite- debaoite- copper silicarsenate association, (2) the scorodite- carminite- beudan-tite-bayldonite- duftite association, and (3) the scorodite-Ba-bearing pharmacosiderite- dussertite association. Arsenate minerals are formed generally in the oxidized zone of the sulfide-type deposits which lie in thewarm, humid and rainy torrid-subtropical zone with pH=6-8 and contain large amounts of arsenopyrite andcarbonate rocks.

Lead Exposure and Oxidative Stress in Coal Miners

We aimed to investigate the short-term correlation between blood lead levels and oxidative stress generation in coal miners. The study involved 94 male coal miners from the Velenje Coal mine, arranged into four groups： three groups according to the number of consecutive working days, and a fourth control group. Miners who worked for three consecutive days had higher blood levels of lead and 8-isoprostane than the control group（P 〈 0.001）. Correlation between lead and 8-isoprostane was of medium strength（r = 0.512, P 〈 0.001）. Short-term lead environmental exposure can potentially harmful and should be considered when formulating improvements in working processes.

Structural Analysis of Hydroxamate Reagents by X-Ray Diffraction

Axis House manufactures and supplies alkyl hydroxamate reagent of various carbon chain lengths for application in flotation of oxide copper and other minerals. As a part of reagent performance improvement, the structural factors of hydroxamate are examined by various analytical tools in particular with X-ray diffraction of single crystals. In a recent publication, the structures of n-octyl hydroxamic acid and its corresponding potassium salt are presented with findings of hydroxamic functional group geometric preference, H-bonding, keto-enol tautomerisation, acid-salt aggregation and alignment of carbon chain. In this paper, an example of branched alkyl hydroxamate3,5,5-trimethyl hexyl hydroxamate. hydroxamate is presented and compared with the result of linear alkyl

Fabrication of nc-Si/SiO_2 structure by thermal oxidation method and its luminescence characteristics

Nano-crystalline silicon/silicon oxide （nc-Si/SiO2） structures have been prepared from amorphous silicon films on both silicon and quartz substrates by using electron-beam evaporation approach and annealing at temperatures about 600 ℃ in air. As a thermal oxidation procedure, the annealing treatment is not only a crystallization process but also an oxidation process. Scanning electron microscopy is employed to characterize the surface morphology of the nc-Si/SiO2 layers. Transmission electron microscopy study shows the sizes of nc-Si grains on the two different substrates. The nc-Si/SiO2 structures exhibit visible luminescence at room temperature as confirmed by photoluminescence spectroscopy. Comparing the photoluminescence spectra of different samples, our results agree with the quantum confinement-luminescence center model.

High energy optically pumped NH_3 terahertz laser with simple cavity

A high energy pulsed terahertz（THz） laser is studied experimentally.The laser cavity simply consists of a quartz glass waveguide,a coated GaAs input window,and a crystal quartz output window.NH3 is filled in the cavity as gain medium,and pumped by an 8-J line-tunable transversely excited atmospheric（TEA） CO_2 laser.When 9R（16） transition acts as the pump line,55.6-mJ THz radiation（90μm） is obtained at 730-Pa NH_3 pressure.The corresponding conversion efficiency is 13.54%.Energy and optimal pressure of amplified spontaneous emission and laser oscillation are compared.

Widely tunable optical parametric oscillator in periodically poled congruently grown lithium tantalite whispering gallery mode resonators

We demonstrate a tunable optical parametric oscillator in a periodically poled congruently grown lithium tantalite whispering gallery mode resonator. The resonator is mechanically polished to millimeter size, and the quality factor is approximately 107 at 1064 nm. Our experiments show that this kind of resonator is capable of reaching a very low threshold and having a wide tuning range. Combined with its narrow resonant linewidth,it is potentially used as a compact, widely tunable, and narrow-linewidth infrared to mid-infrared laser source.

Effect of sodium tartrate concentrations on morphology and characteristics of anodic oxide film on titanium alloy Ti–10V–2Fe–3Al

The effect of sodium tartrate concentrations on morphology and characteristics of anodic oxide film on titanium alloy was investigated. The alloy substrates were anodized in different concentration solutions of sodium tartrate with the addition of PTFE emulsion and their morphology and characteristics were analyzed. The anodic oxide film presented a uniform petaloid drums and micro-cracks morphology. Additionally, micro-cracks dramatically swelled with the increase of the tartrate concentrations. The thickness of the anodic oxide film increased with the concentrations until the concentration reached 15 g/L. The results of Raman analysis illustrate that all samples have similarity in the crystal structure, consisting of mainly amorphous TiO2, some anatase TiO2and a small amount of rutile TiO2. And the ratios of anatase TiO2and rutile TiO2increase with the concentrations until it reaches 15 g/L. Furthermore, the intensity of the peaks increases with enhanced concentrations until the concentration reaches 15 g/L. The corrosion resistance of the anodic oxide film is increased by the sodium tartrate with higher concentrations before 15 g/L. The coefficient of friction of the anodic oxide film reduces with the concentrations until the concentration reaches 15 g/L, then the coefficient of friction of the anodic oxide film increases with the concentrations. © 2015 The Authors

Photooxidation of arsenic(Ⅲ) to arsenic(Ⅴ) on the surface of kaolinite clay

As one of the most toxic heavy metals, the oxidation of inorganic arsenic has drawn great attention among environmental scientists. However, little has been reported on the solar photochemical behavior of arsenic species on top-soil. In the present work, the influencing factors（p H, relative humidity（RH）, humic acid（HA）, trisodium citrate, and additional iron ions） and the contributions of reactive oxygen species（ROS, mainly HO^- and HO2^-/O2^-） to photooxidation of As（Ⅲ） to As（Ⅴ） on kaolinite surfaces under UV irradiation（λ = 365 nm）were investigated. Results showed that lower p H facilitated photooxidation, and the photooxidation efficiency increased with the increase of RH and trisodium citrate.Promotion or inhibition of As（Ⅲ） photooxidation by HA was observed at low or high dosages, respectively. Additional iron ions greatly promoted the photooxidation, but excessive amounts of Fe^2＋competed with As（Ⅲ） for oxidation by ROS. Experiments on scavengers indicated that the HOUradical was the predominant oxidant in this system.Experiments on actual soil surfaces proved the occurrence of As（Ⅲ） photooxidation in real topsoil. This work demonstrates that the photooxidation process of As（Ⅲ） on the soil surface should be taken into account when studying the fate of arsenic in natural soil newly polluted with acidic wastewater containing As（Ⅲ）.

Synthesis of ZnO Nanoparticles onto Sepiolite Needles and Determination of Their Sensitivity toward Humidity, NO_2 and H_2

This work investigated the sensitivity toward humidity, NO2 and H2 of ZnO modified sepiolite （Si12Mg8O30（OH）4.（H2O）4.8H2O）. To this aim, sepiolite powder was first modified by leaching magnesium ions in HCI then by precipitating nano-sized Zn-based compounds under basic conditions. A subse- quent thermal treatment at 550 ℃ for 1 h was performed. The powders were characterized by X-ray diffraction （XRD）, specific surface area measurements, thermogravimetric and differential thermal anal- ysis and field emission scanning electron microscopy, as well as high resolution transmission electron microscopy. The XRD patterns showed that all leached heat treated samples were made of anhydrous sepiolite and of ZnO. Sensors were then obtained by screen printing these materials onto commercial alumina substrates with Pt electrodes. All the investigated compositions were capable of detecting NO2 down to ppm level and 20 ppm H2, at an optimal working temperature of 300°C. These detection limits are in line with the current best results reported in literature.