Rb Concentrations Research Articles

Optoelectronic properties of all-Inorganic lead-free halide double perovskites (RbxCs1-x)2AgBiBr6 for solar cell applications

Solar cells based on lead-free double perovskites as absorber layer is an environment friendly, stable alternative for the conventional lead based hybrid halide perovskites. A comprehensive theoretical study on the optical and electronic properties of all-inorganic double perovskite with A2BB’X6 stoichiometry is done using density functional theory. Doping studies on (RbxCs1-x )2AgBiBr6 perovskite is done using the virtual crystal approximation method within density functional theory. It is found that as increasing the Rb content (x) from 0.0 to 1.0 in RbxCs1-xAgBiBr6, the lattice parameter, dielectric constant and band gap are found to be decreasing linearly in accordance with Vegard's law. The lattice constant decreases linearly in x with a function of a(x) = 11.516 - 0.0057 x (Å), while the band gap decreases linearly as a function of x, Eg(x) = 1.472 - 0.0009 x (eV). Opto-electronic properties of substitutional doping of Rb in (RbxCs1-x)2AgBiBr6 is compared with Cs2AgBiX6 (X=Cl, Br, I) and Br doped Cs2AgIn(BrxCl1-x)6.

Tracing the past from the analysis of Cu, Zn, Mn, Sr, and Rb in Archaeological Dark Earth soils from the tropics and temperate zone

The analysis of minor/microelements in anthropogenic soils resulting from past settlement activities in different environmental conditions and geographical regions is not well-known. The study aimed to determine whether minor/microelements are suitable proxy indicators of past human activities of Archaeological Dark Earth (ADE) soils from two past hilltop settlements- Ziavi-Galenkuito in Ghana and Dřevíč hillfort, Czech Republic. Total and plant-available (Mehlich 3) contents of minor/microelements were determined using portable X-Ray Fluorescence spectrometry and Inductively coupled plasma mass spectrometry, respectively. The black color of the soils from Ziavi-Galenkuito and Dřevíč hillfort contrasted the brownish Ferric Acrisol and greyish Luvic Cambisol control, respectively. The contents of total and plant-available Cu, Zn, Mn, Sr, and total Rb was substantially higher in both sites compared to their control of the same geological substrates. The highest total and plant-available Mn content in Ziavi-Galenkuito may indicate specific intensive settlement activities in a comparatively shorter duration. The highest total Cu, Zn, Sr, and Rb content in the soil from Dřevíč hillfort compared to Ziavi-Galenkuito related to longevity and intensity of the past human activities. Total Cu, Zn, Mn, and Sr can well reflect past human activities from different geographical regions according to their significant correlations from both studied sites. Except for Mn and Sr, total and plant-available content of Cu and Zn were not well correlated. Except for Mn and Sr, total and plant-available content of Cu and Zn were not well correlated. In the calculation of enrichment factors in ADE soils for geoarchaeological purposes, total Mn, Cu, Zn, and Sr are more suitable. Enrichment by minor/microelements can be reliable enough in predicting past human activities in ADE soils of different geology and climatic conditions, even after hundreds of years.

The role of melting on the geochemical evolution and isotopic variability of an anatectic complex in the Iberian Variscides

The genesis and evolution of migmatite-granite terranes usually involve several complex petrological and geochemical processes that leave their imprint on elemental and isotopic signatures. In this paper, we assess the role of melting reactions on the genesis of the variscan Figueira de Castelo Rodrigo-Lumbrales Anatectic Complex (FCR-LAC) in the Central Iberian Zone that culminated in the generation of abundant S-type granites. At odds with the proposed for several anatectic complexes elsewhere, here we demonstrate that no isotopic (Sr-Nd-Hf-Pb) disequilibrium occurred in the FCR-LAC, either in the transitions from metatexites to diatexites nor to granites. However, variable contribution of the source minerals generated batches of melts characterized by distinct parent/daughter ratios, which explain the significant heterogeneity of present-day isotopic signatures. While Rb/Sr ratios and the Pb budget of the successively generated lithotypes were mainly controlled by major minerals such as muscovite, K-feldspar and plagioclase, the accessory phases played a major control on the Sm/Nd and Lu/Hf ratios. Our study also demonstrates the existence of two distinct diatexite groups produced by different melting reactions. Type-1 diatexites, having high Rb contents and fractionated HREE, are geochemically akin to the associated S-type granites. They were produced by dehydration-melting of muscovite with production of peritectic K-feldspar, sillimanite and melt. The less abundant type-2 diatexites required influx of external fluids for melting, which consumed more plagioclase than muscovite.Isotopic data reveal the existence of two groups with distinct initial compositions (εNd320 = −5.05 to −6.03 and εHf320 = −3.42 to −4.45 vs. εNd320 = −7.30 to −8.89 and εHf320 = −6.45 to −8.47), both composed of metatexites, diatexites and granites, due to source heterogeneity. The main source of the anatectic complex was the metasedimentary Neoproterozoic – lower Cambrian Douro-Beiras Supergroup, with minor contribution of Ordovician, Ollo de Sapo magmatic rocks.

Rabeprazole inhibits several functions of Entamoeba histolytica related with its virulence.

Amoebiasis is a human parasitic disease caused by Entamoeba histolytica. The parasite can invade the large intestine and other organs such as liver; resistance to the host tissue oxygen is a condition for parasite invasion and survival. Thioredoxin reductase of E. histolytica (EhTrxR) is a critical enzyme mainly involved in maintaining reduced the redox system and detoxifying the intracellular oxygen; therefore, it is necessary for E. histolytica survival under both aerobic in vitro and in vivo conditions. In the present work, it is reported that rabeprazole (Rb), a drug widely used to treat heartburn, was able to inhibit the EhTrxR recombinant enzyme. Moreover, Rb affected amoebic proliferation and several functions required for parasite virulence such as cytotoxicity, oxygen reduction to hydrogen peroxide, erythrophagocytosis, proteolysis, and oxygen and complement resistances. In addition, amoebic pre-incubation with sublethal Rb concentration (600μM) promoted amoebic death during early liver infection in hamsters. Despite the high Rb concentration used to inhibit amoebic virulence, the wide E. histolytica pathogenic-related functions affected by Rb strongly suggest that its molecular structure can be used as scaffold to design new antiamoebic compounds with lower IC50 values.

Geochemistry and Sr-Nd Isotopes of the Oligo-Miocene Bagh-e-Khoshk Granitoid in SE of the UDMA, Iran: Implications for Petrogenesis and Geodynamic Setting

Oligo-Miocene Bagh-e-Khoshk granitoid stock is intruded into the Eocene volcanic rocks in the southeastern part of the Urumieh-Dukhtar Magmatic assemblage in Iran. The granitoids are mainly consisting of diorite, quartz diorite and granodioritic rock types. They are metaluminous to slightly peraluminous, medium to high K calc-alkaline, with SiO2 ranging from 50.2 to 66 wt.%. The major elements mostly define linear trends and negative slopes with increasing of SiO2, while K2O is positively correlated with silica. There is a higher content of Ba, Rb, Nb and Zr elements with increasing SiO2, whereas Sr shows an opposite behavior. Primordial mantle-normalized multi-element patterns show enrichment in LILE relative to HFSE with distinctive Nb, Ta, Ti negative anomalies. These signatures are typical of subduction related magmas that formed in an active continental margin. The high Ba/La Ba/TiO2, Ba/Nb and Th/Nb ratios emphasizes the significant involvement of fluids during subduction processes. The chondrite-normalized REE patterns of the Bagh-e-Khoshk granitoids show an enrichment in light REEs ((La/Yb)n = 3.84, 7.41), very slightly HREE fractionation patterns ([Gd/Yb]n=1.26–1.83) and small positive Eu anomalies (EuN/EuN* = 1.01, 1.44) in diorites. Whole-rock Sm–Nd isotope analysis give eNd values (+2.91 to +3.29) and Sr ratios (0.7046–0.7053). The geochemical characteristics, positive eNd and low Sr ratios of the Baghe-Khoshk granitoids suggest their formation from partial melting of the mantle wedge source, at pressures below the garnet stability field, modified by fluids during subduction processes.

On the age of pyrochlore carbonatites from the Ilmeno-Vishnevogorsky Alkaline Complex, the Southern Urals (insights from Rb-Sr and Sm-Nd isotopic data)

Research subject. In this research, we carried out Sm-Nd- и Rb-Sr-dating of pyrochlore carbonatite from the Vishnevogorsky niobium deposit, Ilmeno-Vishnevogorsky Alkaline Complex, Southern Urals. IVC is located in the Ural fold region and is a carbonatite complex of the linear type. Rare metal (Nb-Zr-TR) deposits and occurrences are related to IVC. The age and the duration of IVC deposits formation remains a matter of debate. To determine the age of IVC carbonatites and related niobium ore, we measured Sm-Nd and Rb-Sr isotopic compositions and concentrations of the elements in the minerals (pyrochlore, calcite, apatite, biotite) and bulk sample of pyrochlore carbonatite. Materials and methods. The Sm and Nd isotopic compositions and concentrations were determined on a Finnigan MAT-262L (RPQ) seven-collector mass spectrometer in the static regime at the Geological Institute of the Kola Scientific Center, Apatity, Russia. The Sr and Rb isotopic compositions and concentrations were determined on thermos-ionization mass spectrometer Triton Plus (“Geoanalitik”, IGG UD RAN, Ekaterinburg, Russia). Results. Age of pyrochlore carbonatites from ore zone 140 (Vishnevogorsky deposit, IVC) defined by Sm-Nd and Rb-Sr isotopic methods. Mineral Sm-Nd-isochron (5 points) indicated age 229 ± 16 Ma, mineral Rb-Sr-isochron (5 points) showed similar age 250.5 ± 1.2 Ma. Conclusions. Results Sm-Nd и Rb-Sr dating indicate that the pyrochlore сarbonatites of ore zone 140 crystallized ≈ 250 Ma ago, at the stage of the postcollisional extension, possibly, in connection with exhumation complex, which was accompanied by decompression, partial melting of rocks, involving fluids, dissolution and precipitation of Ordovician-Silurian alkaline-carbonatitе complex. Thus, the formation of the IVC carbonatites and related Nb-ore, which began in Silurian (S), continued in Permian (P) and Triassic (T1-2) and was associated with the post-collision stage of tectonic activity in the Ural Fold Belt.

The Southeastern Saurashtra dyke swarm, Deccan Traps: Magmatic evolution of a tholeiitic basalt–basaltic andesite–andesite–rhyolite suite

The Deccan Traps continental flood basalt (CFB) province of India contains several dyke swarms, which are dominated by tholeiitic basalts and basaltic andesites. The Southeastern Saurashtra dyke swarm, containing mainly these rock types, also contains an andesite and several rhyolites. Based on petrographic, mineral chemical, and whole-rock major and trace element and Sr-Nd isotopic data, we discuss the magmatic evolution and pressure-temperature conditions of crystallisation of these dyke magmas. The tholeiitic basalts and basaltic andesites have low to moderate TiO2 contents. The andesite and the rhyolites have low CaO, MgO, Fe2O3t, TiO2 and P2O5, and high K2O, Rb, Ba and light rare earth element contents. Thermobarometric calculations for equilibrium mineral–whole-rock pairs indicate plagioclase crystallisation at 1200–1170 °C, overlapping with clinopyroxene crystallisation at 1181–1143 °C, and a pressure range of 0.1–3.6 kbar indicating crystallisation during magma ascent or storage at shallow crustal levels. Major and trace element modelling is consistent with the rhyolites being produced by advanced fractional crystallisation of basaltic parental magmas. However, a broad trend of increasingly radiogenic Sr and nonradiogenic Nd isotopic ratios, from the mafic rocks through the andesite to the rhyolites, suggests a combined assimilation and fractional crystallisation (AFC) process between basaltic magma and ancient granitic crust. The rhyolites contain the largest crustal contributions and display the most “enriched” Sr-Nd isotopic characteristics yet recorded from the Deccan Traps (εNdt = −20.6, (87Sr/86Sr)t = 0.74855). The widespread occurrence of mafic enclaves in the rhyolite dykes suggests that processes such as magma mixing may also be responsible for some of the andesitic rocks known in Saurashtra.

Peculiarities of the Rb–Sr Isotope System in Granites: Comparative Study Results for Fresh and Altered Plagioclase Varieties from the Raumid Pluton Leucogranites (Pamirs)

Plagioclase varieties from leucogranites of the Raumid pluton (Pamirs) were studied by isotope Rb–Sr method. The studied varieties are: (1) fresh, crystal-clear magmatic oligoclase and (2) altered by deuteric saussuritization, turbid plagioclase. Comparison of data obtained for the coexisting varieties shows that saussuritization of the leucogranites led to Rb and Sr content and 87Rb/86Sr growth, and (87Sr/86Sr)0 distortion. This imply gain of alkaline and alkaline earth elements during saussuritization. The case of the Raumid pluton suggests a possibility of the gain from country rocks.

A cell size sensor

Cell Cycle Efforts continue to uncover the long-sought mechanism by which cells coordinate growth and cell division to maintain a constant size. Zatulovskiy et al. propose that human cells sense the concentration of the retinoblastoma family protein Rb. Rb itself acts on transcription factors to inhibit progression through the cell cycle. As cells grow, the concentration of Rb decreases by dilution, and the cell can then divide. In mice heterozygous or homozygous for an Rb gene deletion, the size of liver hepatocytes decreased—and variability in cell size increased—as each Rb allele was lost. Science , this issue p. [466][1] [1]: /lookup/doi/10.1126/science.aaz6213

Coupled controls of climate, lithology and land use on dissolved trace elements in a karst river system

As an important factor affecting water quality, dissolved trace element (DTE) is not well studied in the karst region. Here, eighteen DTEs were analyzed to investigate their contents, seasonal-spatial variations, sources and controlling factors, and to evaluate water quality and health risks in a karst river system (Chishui River, southwestern China). The results showed that dissolved trace element concentrations (DTECs) in this river were at a relatively low level compared with other Chinese rivers. Except for Cr, Ni, Sr and U, other DTEs had a higher median concentration in the wet period than in the dry period. Water quality and health risk assessments indicated that the water quality in this river had no extensive heavy metal pollution, and the DTECs were below the hazard level. Correlation analysis and principal component analysis identified that Al, Co, Cu, Li, Mn, Ni, U, Mo, Sb and Sr were mainly derived from natural sources, while As, Ba, Cr, Ga, Pb, Rb, V and Zn were dominated by anthropogenic sources. Carbonate and urban land distributions control the DTECs of river waters, indicated by correlations of DTECs with coverage of carbonate and urban land within the draining area. Further analyses found that for mono-lithological sub-catchments with low urban land coverage, the water samples from carbonate catchments had a higher concentration of Co, Cr, Ni, U, Mo, Li and Sr and a lower concentration of Ga, Pb, Sb, Cu, As, Rb, V, Mn, Zn, Al and Ba than the water samples from silicate catchments. These differences would be changed with the increasing of urban land coverage in mono-lithological sub-catchments, suggesting that the impacts of urban land on DTEs are not limited to As and Rb indicated by correlation analyses. Seasonal changes in contents of DTEs and in their correlations with analyzed factors reflect the regulations of seasonal hydrologic conditions. This study highlights that the DTECs of river waters in the Chishui River basin, a region with low level of urbanization, are significantly related to urban land distribution. Future urban planning and watershed management need consider the impacts of urbanization on the DTEs and water quality in rivers in karst areas.

Chemical signature of quartz from S- and A-type rare-metal granites – A summary

About 800 new and 1200 already published laser ablation inductively coupled plasma mass spectrometry analyses of quartz from rare-metal granites and related greisens, quartz-tourmaline rocks and quartz veins were evaluated in order to define typical trace-element signatures of quartz of different origin. The studied dataset comprises typical examples of sub-aluminous to slightly peraluminous plutons (A-type granites of the Kimi stock, Finland; Eastern Erzgebirge, Czech Republic; Orlovka, Russia and Ongon Chairchan, Mongolia), and strongly peraluminous plutons (S-type granites of Beauvoir, France; Cornwall, England; Panasqueira and Argemela, Portugal; Western Erzgebirge, Czech Republic). Additional 700, mostly already published, analyses of quartz from barren granites of all geochemical types (I, S, A-type), rhyolites and barren and rare-element pegmatites were evaluated for comparison. Compiled data reveal high diversity in the contents of trace elements in quartz even among rocks of similar geochemical composition. The most common trace elements in magmatic quartz are Al, Li and Ti with medians of 447, 39.6 and 17.4 ppm in S-type rare-metal granites, and 160, 15 and 6.6 ppm in A-type rare-metal granites. The contents of all these elements in greisens and quartz veins are significantly lower than in their parental granites. Al contents above 450 ppm should serve as a reliable indicator of S-affinity of the analyzed granite, while contents <250 ppm Al are typical for A-type rocks. The contents of Al, Ge and Rb generally increase in the course of magmatic fractionation, while the contents of Ti decrease. The Ge/Ti value can be taken as a valuable indicator of fractionation of granitic melt from which quartz crystallized: this value was found to generally range from 0.002 to 0.2 in quartz from common granites. It may, however, reach 1 in most rare-metal granites (Erzgebirge, Panasqueira, Cornwall), 10 at Beauvoir, 35 at Orlovka, and 50 at Argemela. The uptake of Li into quartz is limited by Al contents in quartz and affected by the contents of volatiles in the melt; it does not correlate with Li contents in parental melt and cannot be used as an indicator of Li-rich magmatic systems.

Diverse origins of pyroxenite xenoliths from Yangyuan, North China Craton: implications for the modification of lithosphere by magma underplating and melt-rock interactions

We present detailed major-, trace-element and Sr-Nd-Mg isotopic geochemistry for a suite of pyroxenite xenoliths entrained in Oligocene basalts in Yangyuan county, North China Craton, to reveal their origins and to further constrain the evolution of the lithospheric mantle beneath this area. The Yangyuan pyroxenites exhibit a lithologic spectrum ranging from orthopyroxenite, through orthopyroxene-rich websterite and clinopyroxene-rich websterite to clinopyroxenite. Their equilibrium temperatures (874–975 °C), which are within the temperature range of the upper mantle and lower crust, suggest that they came from the crust-mantle transition zone. The Yangyuan pyroxenite xenoliths can be subdivided into three types based on the compositions of their constituent clinopyroxene. Clinopyroxenes in the type I pyroxenites are characterized by high Mg# (88.3–92.0; Mg# = Mg/(Mg + Fe2+)*100) and Cr2O3 contents (0.86–1.63 wt.%). Their resemblance to those from the peridotite xenoliths, together with their light rare earth element (LREE) enrichment, indicates that the type I pyroxenites should be produced by lithological heterogeneity in the mantle, which may have including metasomatism. Clinopyroxenes in the type II pyroxenites have intermediate Mg# (81.0–86.7) and Cr2O3 contents (0.53–0.73 wt.%), which are similar to those of strongly metasomatized mantle-derived Fe-lherzolite xenoliths. Their LREE-enriched compositions, as well as the high Ni contents of the orthopyroxenes and clinopyroxenes, suggest that the type II pyroxenites were produced by melt-peridotite interactions. Clinopyroxenes from type III pyroxenites have the lowest Mg# (65.2–76.5) and Cr2O3 contents (0.05–0.38 wt.%), which are comparable to those formed by fractional crystallization of primary basalts, suggesting that they are the products of fractional crystallization. The high Mg#, Ti/Eu ratios, the low (La/Yb)N and Ca/Al ratios, and Rb and Ba contents of the clinopyroxenes, as well as the depleted Sr-Nd isotopes of most of the Yangyuan pyroxenites, suggest that asthenosphere or juvenile lithospheric mantle-derived silicate melts were probably involved in their formation, whereas the enriched Sr-Nd isotopes of sample YY17-5 indicate that its source may have mixed with melts derived from recycled ancient lower crust. The light and variable Mg isotopic compositions (δ26Mg = −0.23 to −0.46‰) of the Yangyuan pyroxenites suggest contributions from a subducted oceanic slab. The diverse origins of these pyroxenite xenoliths provide evidence that the deep lithosphere beneath Yangyuan has been modified by multiple melt-rock interactions and magma underplating.

Early Evolution of Himalayan Orogenic Belt and Generation of Middle Eocene Magmatism: Constraint From Haweng Granodiorite Porphyry in the Tethyan Himalaya

Although the Himalayan orogenic belt is dominant by Oligocene to Miocene leucogranites, it initiated magmatic activity from middle Eocene. However, the exact distribution and genesis of early magmatism is yet to be resolved. This study identified new outcrops of middle Eocene magmatism, Haweng granodiorite porphyries, from northwest Langkazi in the northern Tethyan Himalaya, southern Tibet. Identical zircon U–Pb ages were obtained by secondary ion mass spectrometry (SIMS) (17JT13: 45.3±0.4 Ma; 17JT16: 44.5±0.8 Ma) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) (17JT15: 44.3±0.8 Ma; 12FW75: 44.4±0.6 Ma) method for different outcrops there. Titanite LA-ICP-MS U-Pb analyses also gave consistent lower intercept ages for samples 17JT13 (45.3 ± 0.5 Ma) and 17JT15 (44.5 ± 0.6 Ma). Zircon metamorphic rims of sample 17JT15 recorded a younger thermal event of 29.9±0.4 Ma. The analyzed samples possess high SiO2 (69.98–73.53 wt.%), Al2O3 (15.07–16.15 wt.%), variable Na2O (3.94–5.81 wt.%) with Na2O/K2O ratios of 1.57–7.88, and A/CNK values of 1.08–1.27 indicative of sodic peraluminous series. They show variable Sr (342–481 ppm), Rb (37.9–133 ppm) concentrations, and low Rb/Sr ratios (0.10–0.39), radiogenic Sr isotopes (87Sr/86Sr(t): 0.7190 to 0.7251) and unradiogenic Nd–Hf isotopes with eNd(t) values of -13.54 to -11.55 and eHf(t) values of -11.97 to -9.37, respectively. The variation of major and trace elements, such increase of Na2O and Sr, and decreases of K2O and Rb, resulted from cumulation of plagioclase and crystal fractionation of K-feldspar during magma evolution. The Haweng granodiorite porphyries were derived from partial melting of dominant amphibolites and variable metasedimentary rocks. The newly identified outcrops help conform the EW trending middle Eocene magmatic belt along the Yarlung Tsangpo suture zone, resulting from breakoff of Neo-Tethyan slab at ca. 45 Ma.

Combined LA-ICP-MS and cryo-SEM-EDS: An improved technique for quantitative analysis of major, minor, and trace elements in fluid inclusions in halite

Quantitative multi-element analyses of single fluid inclusions in halite and other sedimentary minerals can provide information on the origin and chemical evolution of ancient surface waters on Earth. Integrated laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and cryogenic-scanning electron microscopy-energy dispersive spectroscopy (cryo-SEM-EDS) were used here for the quantitative analysis of fluid inclusions in halite. Single phase fluid inclusions in modern and ancient halite were analyzed using a 193 nm ArF excimer laser ablation system coupled with a quadrupole mass spectrometer to test a new calibration technique using magnesium (Mg) as an internal standard. Mg concentrations obtained by cryo-SEM-EDS analyses of fluid inclusions were used to convert LA-ICP-MS concentration ratios into absolute elemental concentrations. Mg concentrations of ancient fluid inclusions from cryo-SEM-EDS analyses were reproducible to better than 5% relative standard deviation (RSD). Comparison between the chemical composition of modern Dead Sea brine measured using ICP-OES (optical emission spectroscopy) and the composition of fluid inclusions in Dead Sea halite formed from those brines, shows that fluid inclusions in halite faithfully record the chemistry of the brines from which they precipitated.Overall LA-ICP-MS analytical precision for major ions K, Ca, S in SO4 (above 50 mmol/kg H2O) is better than 10% RSD and accuracies range from 2% to 21%. Mean concentrations of Li, B, Sr, Rb and Ba agree within 7% of their expected values and are reproducible within 15%, whereas Cs concentrations above detection limit are typically reproducible to within 15 to 25% RSD. For trace elements in seawater, such as U and Mo, quantitative analyses in fluid inclusions are achieved at concentrations above 20 nmol/kg H2O. The results from this study confirm that the precision and accuracy of major and minor elemental analysis is improved with Mg as an internal standard instead of Na and Cl used in previous studies. Controlled, optimized ablation of >30 μm fluid inclusions in halite improved the accuracy and precision and reduced the overall limit of detection (LOD) by one order of magnitude compared to previous studies. Wide ranges of LODs, between 0.7 nmol/kg H2O and 10 mmol/kg H2O, reflect variations in inclusion volume and elemental concentrations. Analytical accuracies obtained for major elements demonstrate that cryo-SEM-EDS and LA-ICP-MS are complementary microbeam techniques for chemical analysis of individual fluid inclusions in halite.

Distribution, sources and ecological risk of trace elements and polycyclic aromatic hydrocarbons in sediments from a polluted urban river in central Bangladesh

To assess the spatial and layer-wise distributions of 26 elements (Na, Al, Mg, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Sb, Co, Ba, Zn, Rb, Cs, La, Ce, Sm, Eu, Yb, Ta, Hf, Th and U) as well as the spatial distributions of polycyclic aromatic hydrocarbons (PAHs) in a polluted urban river (Turag, Bangladesh), benthic sediment samples from 11 different sampling stations were analyzed. Concentrations of Ti, Cr, Mn, Zn, Rb and Cs ranged from 2330 to 5490, 23–116, 186–4298, 34–7345, 77–186 and 2.19–12.0 μg.g−1(dw), respectively, whereas concentrations of ∑PAHs ranged from 45.8 to 1901 with an average value of 432 μg.kg−1(dw) in surface sediments. Geo-accumulation index, enrichment factor and pollution load index were used to assess the contamination level. Among the 26 elements, Zn is identified as the major elemental contaminant which shows significant layer-wise variations (RSDs: 21.7–221 %) at all sampling sites. Similarly, Cr, Mn, Ti, V, Fe and Co show layer-wise variation in some specific sampling sites which invokes variable contamination flux over the industrialization and/or urbanization period. Principal component analysis (PCA) and correlation study ascertained several anthropogenic sources for heavy metal contaminations. Although rare earth elements (La, Ce, Sm, Eu and Yb) seem to have crustal origin, their layer-wise variations are assumed to represent the sediment response toward the pollution load. Integrated study based on the diagnostic ratios and PCA depicted that pyrolytic origins mostly govern the PAHs distributions. Sediments quality guidelines (SQGs) indicated that the highest potential ecological risks occurred for Zn and fluorene at some specific sampling sites.

Expression analysis of transcription factor ERF gene family of Panax ginseng

Ethylene responsive factor(ERF), one of the largest families of transcriptional factors in plants, plays a key role in se-condary metabolism of herbal plants. To analyze the expression of ERF family genes, the heat map clustering method was used by analyzing the ginseng transcriptomes of different parts and different growth years. The contents of ginsenosides Rg_1, Re and Rb_1 in various concentrations of MeJA-treated ginseng adventitious roots were determined by UPLC-MS/MS method. The expression of key genes of ginsenoside biosynthesis(DDS, CYP716A47, CYP716A53v2) and ERF family genes in MeJA-treated ginseng adventitious roots were determined by using real-time quantitative PCR. Pearson correlation was adopted to analyze the gene expression pattern of DDS, CYP716A47, CYP716A53v2 gene and ERF family. The results showed that the content of ginseng diol ginsenoside Rb_1 in ginseng adventitious roots treated with different concentrations of MeJA increased, and the content of ginseng triol ginsenoside Rg_1 and Re decreased. It is consistent with the increase of DDS and CYP716A47 expression and the decrease of CYP716A53v2 gene expression. The expression of ERF003, ERF118 and ERF012 genes was significantly positively correlated with CYP716A53v2, but negatively correlated with DDS. While the expression of ERF1B was significantly negatively correlated with CYP716A47.It is proved that ERF003, ERF118 and ERF012 were likely to inhibit the expression of DDS and promote the expression of CYP716A53v2, and ERF1B was likely to inhibit CYP716A47. This work could provide theoretical basis of ERF functional verification of regulating the biosynthesis of ginsenosides.

GEOLOGY, PETROGEOCHEMISTRY AND CRYSTALLIZATION CONDITIONS OF PLASTOVSKY GRANITOIDS MASSIVE (EASTERN URAL TROUGH)

The article describes the geological structure of the Plastovsky granitoid massif located in the northern part of the East Ural trough. It is composed of granitoids, the formation of which took place in two stages: in the first of them granodiorites, quartz diorites and biotite granites were formed, and in the second - plagiogranites. The massif lies among the metamorphic rocks of the yeremkinsky, oseysky strata and volcanic rocks of the silurian-lower carboniferous age. Chemical composition of the granitoids corresponds to normal alkaline granodiorites and plagiogranites with a predominantly sodium type of alkalinity. According to the content of Rb and Sr, they are derivatives of orogenic andesite magma, clearly fit into the field of tonalite-granodiorite formation and fall into the field of continental trondjemites and quartz diorites. The distribution of rare earth elements in granodiorites and muscovite-biotite granites of the plastovsky complex corresponds to the trondjemites of the continental margins, and in plagiogranites - to the interior of the continents. It was established that the crystallization of the Plastovsky granitoid massif occurred at a temperature of 850 - 1030 °С. The presence of melt inclusions in quartz indicates their primary magmatic nature. The water pressure in the melt was 1460 - 3380 bar, which corresponds to depths of 5 - 11 km (abyssal zone). High content of water (1.0 - 3.1 wt. %), chlorine (0.09 - 0.16 wt. %) and salts (6.2 - 10.2 wt. %) in melt inclusions in quartz granitoids, providing the extraction and transfer of many metals, they make it possible to attribute them to ore-bearing granites of the final plutonic series.

Source and pressure effects in the genesis of the Late Triassic high Sr/Y granites from the Songpan-Ganzi Fold Belt, eastern Tibetan Plateau

The petrogenesis of granites with high Sr/Y signatures similar to adakitic rocks in continental settings is much debated. It is especially controversial whether these rocks are indicative of high-pressure magmatism (i.e., partial melting or crystallization fractionation) related to a thickened crust, or their high Sr/Y signatures are merely inherited from a high Sr/Y source. To address this, new chronological and geochemical data are presented for high Sr/Y granites from the Riluku batholith in eastern Tibetan Plateau. Zircon U-Pb dating and amphibole barometry suggest a final granite crystallization stage of ca. 207 Ma and an emplacement depth of ~14 km (~ 4 kbar), respectively. They are geochemically characterized by high Sr and low Y contents (481–1195 ppm and 6.62–20.6 ppm, respectively) with high Sr/Y and (La/Yb)N ratios (35–112 and 15–113, respectively). Enriched isotope character of the high Sr/Y granites, in combination with regional tectonics, indicates that these rocks are unlikely to be derived from partial melting of subducting oceanic crust. Low Cr (0.8–1.0 ppm), Ni (0.9–3.2 ppm), and Mg# (24–41) suggest that derivation from the partial melting of delaminated lower crust is also unlikely. Water-fluxed partial melting of crustal rocks at low pressure, which preferentially consumes plagioclase over micas, is inconsistent with the high contents of Rb (mostly >150 ppm) and low Sr/Rb ratios (mostly <5) of the samples. Reverse geochemical modeling, which simulated source composition under different pressures, indicates that evaluation of source compositions is critical to constrain the derivation pressure of the high Sr/Y granites. Our study emphasizes that high Sr/Y granites cannot be simply used to deduce a thickened crust at the time of magmatism without a priori knowledge of the nature of the source.

Major, trace and rare earth elements geochemistry of geothermal waters from the Rehai high-temperature geothermal field in Tengchong of China

Major and trace elements geochemistry of high-temperature geothermal waters are important for understanding the subsurface transport and transfer of mass during groundwater circulation. The major constituents and trace elements, including rare earth elements, are discussed to reveal the source of elements and the hydrogeochemical processes occurring in the geothermal waters in the Rehai high-temperature geothermal field in Southwest China. Neutral-alkaline bicarbonate geothermal waters and acid sulfate waters are observed in Rehai due to different genesises. The bicarbonate waters contain higher concentrations of Na, K, Cl, HCO3, Li, Be, F, Sc, Ti, V, Cr, Ga, Rb, Nb, Sb, Cs, W, Tl, Zr and Si and less SO4 than the sulfate waters. The hydrogeochemical analyses show that the recharge of magmatic fluids, mixing with cold water and water-rock interaction affect the concentration of the elements. The geothermal waters and host rock REE chondrite-normalized patterns and the Eu anomalies are inherited from the host rock signature. Negative Ce anomalies may result from oxidative scavenging process of Ce and/or adsorbtion by the precipitation of Fe oxyhydroxides. T, TDS, pH and Fe/Mn minerals all affect the REE concentrations of geothermal waters. Calculations of REE speciation show that in the alkaline waters, Ln(CO3)2- is the major speciation. In the neutral waters, Ln(CO3)2- and LnCO3+ are the main speciation. In the weak acid waters, LnCO3+ is the main speciation and LnSO4+ are the major speciation in the strong acid water.

The Jurassic volcanic–intrusive complex in the Dehua gold orefield, coastal region of SE China: Implications for the tectonic setting and epithermal mineralization

The Dehua gold orefield is an important epithermal gold metallogenic district closely related to volcanic–subvolcanic rocks in the coastal region of the Cathaysia Block, southeastern China. This paper presents new LA-ICP-MS zircon U–Pb ages, elemental and Hf isotopic data for volcanic and intrusive rocks in the Dehua gold orefield. Our results show that the volcanic rocks were produced during the Middle Jurassic (ca. 169–164 Ma), whereas the intrusive rocks were formed in the Late Jurassic (ca. 163–157 Ma). Geochemically, these rocks are characterized by high-K calc-alkaline series and are commonly enriched in LILEs and LREE, depleted in HFSE with negative Nb, Ta, and Ti anomalies, and have lower Ta, Yb, Y and Rb contents, suggesting an arc magma geochemical affinities. Hence, this study firstly reports the Middle Jurassic high-K continental arc volcanic rocks in SE China, implying that the initial subduction of the paleo-Pacific plate began at least in the Middle Jurassic. Besides, in situ Hf isotopic analyses for dated zircon from the volcanic and intrusive rocks yield εHf(t) values range from −9.03 to +1.46 and the Paleo- to Mesoproterozoic two stage Hf model ages. The partial melting of the mixture of ancient continental crust materials and newly underplated potassic-rich mantle-derived mafic magmas likely explains the genesis of volcanic and intrusive rocks in the Dehua gold orefield. In addition, the exposed areas of the Jurassic volcanic rocks in the coastal region of SE China may have great potential to prospect the epithermal deposits.