Barium Concentrations Research Articles

Electrical and magnetic characteristics of barium doped bismuth ferrite via sol–gel auto combustion technique

This study is devoted to the preparation of barium doped bismuth ferrites by sol–gel auto combustion method using different concentrations of barium nitrates Bi1-xBaxFeO3 (x = 0, 0.10, 0.20, 0.30). The Electrical, structural properties, and crystallite size of all samples had been studied. The electrical properties, of the samples, showed compromising results to use in electrical applications. The X-ray diffraction analysis of the samples showed the rhombohedra shape of the samples. The crystallite size were measured and noted to be 24 nm with the enhancement of Ba concentration. The electrical conductivity and resistivity are measured by the mean of two probe methods and results showed an increase in conductivity with the addition of barium. The activation energy were also calculated and recorded to be a 2.07 eV. The magnetic susceptibility of all samples was measured and the response was enhanced by the increase of the Ba concentration. SEM study revealed the morphology of the all prepared samples. The nanoparticles have average particle sizes of 15 and 75 nm, were observed by using image software. The FTIR analysis of all samples resulted the transmittance and the functional group of the all samples.

An experimental study on the effects copper and lead on the seedlings of some economically important vegetable species

Bioaccumulation of toxic heavy metals in vegetables is closely related to the problems of safety concerns as they negatively affect plants in particular those consumed by the humans. Among the food systems the vegetables are the most noticeable foods affected by environmental pollution. Vegetables can take up the metals like copper and lead and store them in excessive levels. Keeping this in view this investigation was undertaken to study the effect of copper and lead concentrations (20, 40, 80, 160, 240, 320, 640, and 1280 µM) and assess their toxic affects on germination and seedling growth at early stages of eight vegetable cultivars; kidney bean, peas, black-eyed bean, artichoke, kale, lettuce, rocket and radish. The results were evaluated by multivariate analysis of variance and Pearson correlation statistical analysis. Our results indicate that the seeds of the vegetables studied by us are generally tolerant to both copper as well lead, except higher concentration exposures which showed no improvement when applied to artichoke (for Cu 1280 µM) and lettuce seeds (Cu 1280 µM; Pb 1280 µM). An application of copper and lead ended up with a decrease in barium, calcium, iron, magnesium, manganese, sodium and zinc content in all seedlings studied. In all vegetables exposed to copper and lead a promotion in copper and lead accumulation was recorded. There was a decrease in nutrient element intake which interrupted the mineral element uptake in the seedlings.

Metal levels in waste pickers in Brasilia, Brazil: hair and nail as exposure matrices

ABSTRACT The aim of this cross-sectional study was to compare workplace conditions and metal exposures in 431 waste pickers who worked nearby at the Estrutural Dump in Brasilia utilizing hair (n = 310) and nail (n = 355) as matrices of exposure. Waste pickers were grouped according to their workplace (open waste dump: G1 and sorting plants: G2). Hair and nail samples were collected and analyzed using ICP-MS. The work duration in the facilities was significantly different between the groups with averages of 16.46 (8.48) yrs and 9.26 (6.28) yrs for hair donors in G1 and G2, and 15.92 (7.72) yrs and 8.55 (5.77) yrs for toenail donors in G1 and G2, respectively. The arithmetic means (μg/g) of cadmium, copper, lead, and manganese in hair were significantly higher in G2 (0.076 ± 0.133; 19.61 ± 18.16; 2.27 ± .56 and 3.87 ± 5.59, respectively) compared to G1 (0.069 ± 0.235; 15.72 ± 15.18; 1.72 ± 4.04 and 3.65 ± 5.5, respectively). Concentrations of arsenic, barium, cadmium, copper, cobalt, lead, manganese, and molybdenum in nail were significantly higher in G2 (0.57 ± 0.39; 22.74 ± 42.06; 0.1 ± 0.08; 22.7 ± 51.60; 0.48 ± 0.45; 4.69 ± 9.43; 19.07 ± 20.75; 1.80 ± 1.76, respectively) compared to G1 (0.40 ± 0.28; 15.32 ± 22.31; 0.08 ± 0.11; 11.91 ± 16.25; 0.37 ± 0.37; 3.94 ± 15.04; 13.01 ± 19.08; 1.16 ± 1.80, respective. Our findings suggest that the studied population was exposed to toxic metals and indicates the need for chemical exposure prevention policies to monitor chemical risk exposures in waste pickers.

Trace Element Geochemistry in North Pacific Red Clay Sediment Porewaters and Implications for Water‐Column Studies

AbstractGeochemical analyses of trace elements in the ocean water column have suggested that pelagic clay‐rich sediments are a major source of various elements to bottom‐waters. However, corresponding high‐quality measurements of trace element concentrations in porewaters of pelagic clay‐rich sediments are scarce, making it difficult to evaluate the contributions from benthic processes to global oceanic cycles of trace elements. To bridge this gap, we analyzed porewater and bulk sediment concentrations of vanadium, chromium, cobalt, nickel, copper, arsenic, molybdenum, barium and uranium, as well as concentrations of the major oxidants nitrate, manganese, iron, and sulfate in the top 30 cm of cores collected along a transect from Hawaii to Alaska. The data show large increases in porewater concentrations of vanadium, manganese, cobalt, nickel, copper, and arsenic within the top cm of the sediment, consistent with the release of these elements from remineralized organic matter. The sediments are a sink for sulfate, uranium, and molybdenum, even though conditions within the sampled top 30 cm remain aerobic. Porewater chromium concentrations generally increase with depth due to release from sediment particles. Extrapolated to the global aerial extent of pelagic clay sediment, the benthic fluxes in mol yr−1 are Ba 3.9 ± 3.6 × 109, Mn 3.4 ± 3.5 × 108, Co 2.6 ± 1.3 × 107, Ni 9.6 ± 8.6 × 108, Cu 4.6 ± 2.4 × 109, Cr 1.7 ± 1.1 × 108, As 6.1 ± 7.0 × 108, V 6.0 ± 2.5 × 109. With the exception of vanadium, calculated fluxes across the sediment–water interface are consistent with the variability in bottom‐water concentrations and ocean residence time of the studied elements.

Structure, morphology, dielectric study of Ba-doped SrTiO3 by sol-gel method for optical applications

The goal of this study is to fabricate barium-doped strontium titanate nanomaterial utilizing the sol–gel technique and a range of barium nitrate concentrations. Electrical Structural properties, CV, FTIR, and SEM of all samples had been studied. The X-ray diffraction (XRD) results of the samples showed the cubic structure of strontium titanate. The Cyclic Voltammetry (CV) is performed on all the samples in light and dark conditions, the results showed enhanced current in the CV graph with the increase of Barium concentration from 5, 10, 15, and 20%. The increase in absorption characteristics were also observed when the doping of Ba increased. The bandgap was measured through resistivity and a decrease in bandgap was noted. Pure SrTiO3 morphology showed an oval/spherical crystalline phase when the dopant concentration was increased to 20%, the results show an asymmetrical shape. Keithley's source meter was used to measure all samples' dielectric characterization, which included the dielectric constant, dielectric loss, electrical susceptibility, and conductivity. The results revealed a decline in the dielectric characteristics. It was also observed that when the doping concentrations increase, the dependency of the samples on frequency as well as on temperature also increases.

Source of inorganic components in the Middle Jurassic inertinite-rich coals of the Southern Ordos Basin, China: With emphasis on formation of Sr- and Ba-bearing minerals

The Middle Jurassic coal seams located in the southern Ordos Basin display notably high concentrations of barium (Ba) and strontium (Sr). To acquire a comprehensive understanding of the source and occurrence of the elevated contents of Ba- and Sr-bearing minerals and their formation mechanism in the coal, a suite of petrological, mineralogical, and geochemical analyses was conducted on the Middle Jurassic coals of the Gaojiapu mine (No. 4 Coal) from the Binchang mining area, using optical microscopy, field emission-scanning electron microscopy, X-ray diffraction, X-ray fluorescence, and inductively coupled plasma mass spectrometry. The results indicate that the No. 4 Coal is a high volatile B bituminous coal, which is characterized by low ash, medium sulfur, and high inertinite contents. The modes of occurrence of minerals identified in the coal, including calcite, dolomite, pyrite, quartz, kaolinite, anatase, barite, and celestine, indicate that the No. 4 Coal may have been subjected to multiple stages of solutions injection. Barium and Sr in the investigated coals are significantly enriched, exhibiting maximum values of 19738 μg/g and 9932 μg/g, respectively, while concentrations of other trace elements are generally depleted. Barite and celestine, generally coexisting with carbonate minerals, commonly occur as cell- and fracture-fillings. Furthermore, the strong correlation coefficients (r) for Ba vs. Ca + Mg and Sr vs. Ca + Mg (0.78 and 0.61, respectively) indicate that most barite and celestine have a close association with carbonate minerals of epigenetic origin. The highly elevated concentrations of Ba and Sr are thought to be primarily derived from solutions leaching barite deposits developed in the Qinling Orogenic Belt, which is located in the south of the Ordos Basin. When mapped spatially, the distributions of Ba and Sr concentrations are fan-shaped, decreasing from the NW to the SE of the mining area. Meteoric water containing dissolved CO2 induced partial dissolution of carbonate rocks, and during this process, selected metal ions (e.g., Ca2+, Mg2+, Al3+, Si2+, Fe2+, Ba2+, and Sr2+) were redistributed and subsequently migrated along fracture zones to the coal seam. The fracture systems and abundant cavities within inertinite in the coal provided sufficient space and conduits for solutions migration.

Single-phase nanopowders of Sr0.85-xBaxEu0.15F2.15: Investigation of structure and X-ray luminescent properties

Novel scintillating and visualizing materials are an essential part of the development of high-power X-ray sources like synchrotrons and free-electron lasers. One of the latest approaches is the formation of composite materials composed of X-ray luminescent nanoparticles in a robust transparent matrix with high thermal conductivity. Here, such Sr0.85-xBaxEu0.15F2.15 nanopowders with a particle size of ≈50 nm were synthesized by precipitation from aqueous solutions. Single-phase solid solutions are formed up to a barium concentration of 70 mol.%. The most intense luminescence band is the band of trivalent europium with a maximum at 590.4 nm, corresponding to the 5D0 → 7F1 transition. The concentration dependence of the X-ray luminescence intensity on the barium content was revealed, and the most optimal composition Sr0.35Ba0.50Eu0.15F2.15 with the brightest luminescence response was determined. The obtained type of nanoparticles has potential applications for the fabrication of new scintillating and visualizing composites.

Barium Promoted Seed Germination and Seedling Growth of Higher Plants in Solution Culture

The effects of various concentrations of barium (Ba) on seed germination and early seedling growth of wheat and mung bean were studied. Ba influenced the seedling growth of wheat and mung bean in similar fashion. Ba enhanced the germination relative index at lower concentration (upto 10 μg ml-1). The relative yield of biomass increased at lower doses of Ba and decreased at higher concentration (>100 μg ml-1). Lower applied doses of Ba showed a maximum index of tolerance while higher applied doses of metal showed a toxic effect on plant growth. The toxic effect of barium on mung bean was more marked than on wheat.

Bioaccumulation of Non-Essential Trace Elements Detected in Women's Follicular Fluid, Urine, and Plasma Is Associated with Poor Reproductive Outcomes following Single Euploid Embryo Transfer: A Pilot Study.

This study aims to determine the association of non-essential trace elements present in follicular fluid, plasma, and urine with reproductive outcomes of women undergoing intracytoplasmic sperm injection (ICSI), preimplantation genetic testing for aneuploidies (PGT-A) and single frozen euploid embryo transfer (SET/FET). This single-center, prospective cohort study included sixty women undergoing ICSI with PGT-A and SET/FET between 2018 and 2019. Urine, plasma and follicular fluid samples were collected on the vaginal oocyte retrieval day to simultaneously quantify ten non-essential trace elements (i.e., Ba, Sr, Rb, Sn, Ti, Pb, Cd, Hg, Sb, and As). We found several associations between the levels of these non-essential trace elements and clinical IVF parameters. Specifically, the increased levels of barium in follicular fluid were negatively associated with ovarian function, pre-implantation development and embryo euploidy, while elevated strontium concentrations in this biofluid were negatively associated with impaired blastulation and embryo euploidy. Elevated plasma strontium levels were negatively associated with ovarian function, fertilization and blastulation. Enhanced presence of other trace elements in plasma (i.e., rubidium and arsenic) were associated with a diminished ovarian function and limited the number of recovered oocytes, mature oocytes and zygotes, respectively. Fully adjusted models suggested significantly lower odds of achieving a live birth when increased concentrations of barium and tin were found in urine.

Associations of circulating multiple metals with the risk of incident hyperuricemia and the average annual change in uric acid levels

BackgroundHyperuricemia has been linked to exposure to certain metals in cross-sectional studies. However, prospective studies evaluating the associations of multiple metal exposures with incident hyperuricemia are scarce. ObjectivesTo prospectively investigate the associations of multiple metal/metalloid concentrations with incident hyperuricemia as well as average annual change in uric acid levels in a longitudinal cohort. MethodsA longitudinal cohort study included 3957 subjects who were free of cardiovascular disease with certain risk factors for cardiovascular disease at baseline. Incident hyperuricemia was ascertained if serum uric acid level was ≥ 420 μmol/L for men and ≥ 360 μmol/L for women during the follow-up visit in 2013. The relationships between 17 single plasma metals/metalloids and incident hyperuricemia were assessed using unconditional logistic regression models. For metals/metalloids significantly related to incident hyperuricemia, we further utilized generalized linear regression models to evaluate their associations with the average annual change in uric acid levels. Finally, we applied the weighted quantile sum (WQS) regression to investigate the joint effects of metals/metalloids on hyperuricemia risk and uric acid changes, and to identify the most significant metals. ResultsAfter adjusting for potential confounders, plasma aluminum, arsenic, barium, lead, strontium, vanadium, and zinc concentrations were positively associated with incident hyperuricemia in both main analyses and sensitivity analyzes. Compared to the lowest quartiles, participants in the highest quartiles had 63 %−125 % higher risks of incident hyperuricemia (all FDR < 0.05). Furthermore, the positive associations of these seven metals with an average annual uric acid increase reinforced the findings. Finally, the WQS analyses showed that plasma metals mixtures were positively associated with the risk of incident hyperuricemia (OR: 1.47; 95 % CI: 1.23, 1.76) and the average annual change in uric acid levels (β: 3.17; 95 % CI: 2.42, 3.93), and strontium and vanadium were the most heavily weighted metals, respectively. ConclusionOur findings identify aluminum, arsenic, barium, lead, strontium, vanadium, and zinc exposures as independent risk factors for hyperuricemia and provide new insights into the prevention of hyperuricemia.

Thermodynamic investigations of steel deoxidation process with calcium and barium

The use of alloys with alkaline earth metals (AEM) it possible to optimize the processes of deoxidation and refining of steel from non-metallic inclusions. The technologies of ladle treatment of the melt with the use of AEM complexes to obtain high-quality metal products even if it is impossible to use expensive equipment (vacuumers, tribe apparatus, etc.), which is often typical for small steel foundries. At the same time, a number of issues related to the mechanisms implemented during the refining of liquid steel with calcium and barium require further study. In the course of this work, the authors constructed state diagrams of double (CaO–BaO) and ternary (FeO–CaO–BaO) oxide systems and carried out thermodynamic modeling of equilibria in the Fe–Ca–Ba–C–O system. It is noted that in this system there is an extensive equilibrium region of the oxide melt with solid solutions of CaO-based oxides. The solubility surfaces of components for the temperatures of steel ladle treatment (1550–1600 °С) and for different carbon contents (0; 0,1; 0,4 % С) are constructed for the studied system. A comparative analysis of the constructed diagrams suggests that a change in the carbon content within the indicated limits does not significantly affect the type of the diagrams. It follows that the revealed patterns will be maintained in the production of a wide range of economically alloyed low-carbon steels. It is shown that during the deoxidation of steel without aluminum, and with a calcium content typical for real production processes (about 30 ppm), the expected active oxygen content is about 30 ppm (log[O] = –2.5), which does not meet modern requirements for purity become. At the same time, a change of the barium content has practically no effect on the degree of deoxidation of the metal. Thus, it is shown that the main role of calcium and, especially, barium in the processing of liquid steel is modification and removal of non-metallic inclusions from the melt

Geobotanical and Biogeochemical Prospecting Method of Complex Sulphide Ore of Pb-Zn-Cu-Ba in Abuni-Adudu areas of the Middle Benue Trough, Nigeria

This research work focused on two plant species namely, the Anogeissus leiocarpus (DC.) and Dichrostachys cinerea for mineral prospecting. The two plants were sampled based on their occurrence, abundance and outlook. Twelve samples (six each of Anogeissus leiocarpus (DC.) and Dichrostachys cinerea) were collected around Abuni-Adudu mining communities in the Middle Benue Trough, Nigeria. In addition, bulk ore and twelve soil samples were also collected and analysed for correlation. Geologically, the study area is made up compacted shale, baked shale (hornfels), and sandstones of sedimentary origin, which are intruded by tertiary basalts of igneous origin. Samples were analysed for elemental composition, using inductively coupled plasma mass spectrometry method. Analysis revealed that the geobotanical method of prospecting for Pb-Zn-Cu-Ba mineralization in the area is promising as biogeochemical data indicated that the Dichrostachys cinerea are good indicator of Pb-Zn-Cu mineralization while the Anogeissus leiocarpus were indicative of Barium. Given the relatively low concentration of Barium in the ore (3.8 ppm) as against concentration in the soil samples, which ranges from 83 ppm (sample YS6) to 552 ppm (sample YS12), Barium has its source from the shale and sandstone or nearby Barite mineralization and not the ore.

Trimester-specific effects of maternal exposure to single and mixed metals on cord serum inflammatory cytokines levels: A prospective birth cohort study

BackgroundCord blood inflammatory cytokines are vital in early-life programming. An increasing number of studies concern the effect of maternal exposure to different metal elements during pregnancy on inflammatory cytokines, but limited studies have explored the association between maternal exposure to mixed metals and cord blood inflammatory cytokine levels. MethodsWe measured serum concentrations of vanadium (V), copper (Cu), arsenic (As), cadmium (Cd), and barium (Ba) in the first, second, and third trimesters and eight cord serum inflammatory cytokines (IFN-γ, IL-1β, IL-6, IL-8, IL-10, IL-12p70, IL-17A, and TNF-α) in 1436 mother-child dyads from the Ma'anshan Birth Cohort. Generalized linear models and Bayesian kernel machine regression (BKMR) were performed to assess the association of single and mixed metal exposure during each trimester with cord serum inflammatory cytokine levels, respectively. ResultsRegarding metal exposure in the first trimester, V was positively associated with TNF-α (β = 0.33, 95 % CI: 0.13, 0.53); Cu was positively associated with IL-8 (β = 0.23, 95 % CI: 0.07, 0.39); Ba was positively associated with IFN-γ and IL-6; As was negatively associated with IFN-γ and IL-17A; and Cd was negatively associated with IFN-γ, IL-1β, IL-12p70, IL-17A, and TNF-α. BKMR revealed that exposure to metal mixtures in the first trimester was positively associated with IL-8 and TNF-α but negatively associated with IL-17A. Moreover, V contributed the most to these associations. Interaction effects were observed between Cd and As and between Cd and Cu with IL-8, and between Cd and V with IL-17A. Among males, As decreased inflammatory cytokines; among females, Cu increased inflammatory cytokine levels, whereas Cd decreased inflammatory cytokine concentrations. ConclusionsMaternal exposure to metal mixtures in the first trimester interfered with cord serum inflammatory cytokine levels. The associations of maternal exposure to As, Cu and Cd with inflammatory cytokines showed sex differences. Further studies are warranted to support the findings and explore the mechanism of the susceptibility window and sex-specific disparity.

Investigation of Ga2O3-BaO-GeO2 glasses for ultrafast laser inscription

From the perspective of developing robust mid-infrared (mid-IR) integrated photonic devices, barium-gallium-germanium (BGG) oxide glasses are strong candidates among other mid-IR glasses. Indeed, compared to fluoride, tellurite or chalcogenide glasses, BGG glasses present the highest thermal and chemical stabilities, while transmitting light up to 6 µm. In parallel to this, technological advances in ultrafast direct laser writing (UDLW)-based devices are driving the development of novel photonic glasses. Specifically, there is a need to identify the most efficient mid-infrared transmitting BGG glass compositions for sustaining the UDLW process. In this article, we thoroughly investigate the BGG physicochemical properties through absorption and Raman spectroscopies, refractive index, density, and glass transition temperature measurements in two relevant glass series: one via a Ga3+/Ge4+ ratio fixed to 1 and a barium content varying from 25 to 40 cationic percent, the other via a 2Ba2+/Ga3+ ratio fixed to 1 and a germanium content varying from 20 to 80 cationic percent. In the meantime, we explore the photosensitivity of these glasses under UDLW. Our findings reveal the valuable role of both barium and gallium ions, notably through their concentration, structural stabilization sites and viscosity influence. Finally, we demonstrate the fabrication of an 8.2 cm-long UDLW-induced waveguide with propagation losses of &lt; 0.3 dB.cm-1 at 1550 nm.

Migration and Reaction Mechanism of Barium in BaSO4–CaCO3–Fe2O3 System during Sintering

With the increasingly strict requirements of blast furnaces on the sinter quality, analyzing the phase transition process and reaction mechanism of special elements in the sintering process plays an important role in understanding the sintering process and improving the sinter quality. Herein, the decomposition process of barite during sintering and the influence mechanism on the bonding phase of calcium ferrite are studied by laboratory experiments and thermodynamic calculations. The results show that calcium ferrite and ferric oxide can promote the decomposition of barite and reduce the decomposition temperature in the sintering process. The generated barium enters the calcium ferrite phase and affects the strength and melting point of calcium ferrite. With the increase of barium content, the strength of calcium ferrite sample increases from 1.62 to 2.00 kPa, and the initial melting temperature of calcium ferrite sample stays at 1473 K. However, with the further increase of barium, the sample strength and melting temperature both show a worsening trend. Finally, based on the research results, some suggestions for sintering production are put forward, and the optimal barite content is determined. Results help to better understand the reaction process and action mechanism of barium in the sintering process.

Characterization, risk assessment, and potential utilization of fly ash from PLTSa Merah Putih at Bantargebang, Bekasi, Indonesia

Municipal solid waste incineration (MSWI) has been adopted in Indonesia to reduce the volume and mass of municipal solid waste. However, as a by-product of waste combustion, fly ash generation cannot be avoided. It can cause an environmental problem if not managed properly. Hence, this study aims to investigate the characteristics of fly ash generated from Indonesia’s first waste-to-energy incineration pilot plant and its potential utilization. Fly ash was characterized using X-Ray fluorescence (XRF), BET surface area measurement, pore size distribution (PSD), scanning electron microscopy with energy-dispersive spectrometry (SEM-EDS), and X-ray diffraction (XRD). The characterization results showed that calcium was predominant, around 28%, followed by titanium, silica, iron, and aluminum, with values of 7.10%, 5.70%, 4.40%, and 4.30%, respectively. These results demonstrated that MSW incineration fly ash was classified as a very active high-calcium fly ash. The surface structure of fly ash was flaky and complex, with some irregular material. The particle size distribution of fly ash shows that the diameters of most particles were nearly 12 μm. The specific surface area of fly ash was 3.06 m2/g, the total-pore volume was 0.01 cm3/g, and the average pore size was 11.82 nm. In addition, the environmental risk assessment was evaluated using the toxicity characteristic leaching procedure (TCLP). TCLP concentrations of heavy metals, including arsenic, barium, beryllium, cadmium, chromium hexavalent, copper, lead, mercury, nickel, selenium, and zinc, were lower than the regulatory level, indicating a low environmental risk. Therefore, it has great potential for utilization as a paving block mixture material.

Morphology and Composition of the Third Body on the Friction Surface of an Organic Composite Railway Brake Shoe

Friction properties are significantly affected by third bodies (films formed on friction surfaces). However, the study of their composition and structure remains incomplete. For this reason, an organic composite railway brake shoe was tested at an initial braking speed of 125 km/h using a full-scale dynamometer. A third body with a thickness of ~120 μm was obtained, and its morphology and composition were analyzed using a multiple techniques. The results indicated that the third body had a layered structure. The upper surface was smoother than the lower surface. The carbon content on the upper surface decreased by 68.01%, and the iron content increased by 11.85 times in relation to that on the lower surface. Compared to the brake shoe, the iron content of the third body increased by 272.81%, and most of the iron was oxidized. Furthermore, the content of barium, calcium, and silicon decreased by more than 33%, and the crystalline structures of the inorganic filler materials, such as graphite and barium sulfate, were destroyed, with new crystalline structures appearing. Finally, the residual weight at 650 °C increased from 90.35% to 96.59%. This research could provide a reference for exploring the friction and wear mechanisms of organic composite railway brake shoes.

Continuous production of gamma aminobutyric acid by engineered and immobilized Escherichia coli whole-cells in a small-scale reactor system

γ-Amino butyric acid (GABA) is a non-proteinogenic amino acid and a human neurotransmitter. Recently, increasing demand for food additives and biodegradable bioplastic monomers, such as nylon 4, has been reported. Consequently, considerable efforts have been made to produce GABA through fermentation and bioconversion. To realize bioconversion, wild-type or recombinant strains harboring glutamate decarboxylase were paired with the cheap starting material monosodium glutamate, resulting in less by-product formation and faster production compared to fermentation. To increase the reusability and stability of whole-cell production systems, this study used an immobilization and continuous production system with a small-scale continuous reactor for gram-scale production. The cation type, alginate concentration, barium concentration, and whole-cell concentration in the beads were optimized and this optimization resulted in more than 95 % conversion of 600 mM monosodium glutamate to GABA in 3 h and reuse of the immobilized cells 15 times, whereas free cells lost all activity after the ninth reaction. When a continuous production system was applied after optimizing the buffer concentration, substrate concentration, and flow rate, 165 g of GABA was produced after 96 h of continuous operation in a 14-mL scale reactor. Our work demonstrates the efficient and economical production of GABA by immobilization and continuous production in a small-scale reactor.

Mineralogie sulfidických rud z Měděné štoly ve zlatohorském rudním revíru

Until 1993, sulfide ores of copper, lead and zinc, as well as native gold were mined in the Zlaté Hory ore district in the Jeseníky Mountains. These deposits occur in the Devonian volcano-sedimentary complex of the Vrbno Group, which consists of quartzites, phyllites, limestones and metamorphic igneous rocks of intrusive and extrusive nature. The main ore bodies are located in a quartzite horizon containing lenses of felsic metavolcanic rocks or in the underlying and overlying rocks (mainly phyllites). Sulfide mineralization of the Měděná Adit in the Zlaté Hory ore district concentrated in greenschists containing three mineral assembblages: i) chlorite + quartz + albite + barian feldspar + siderite + dolomite (ankerite) ± ilmenite, ii) chlorite + phlogopite + quartz + albite + siderite + dolomite (ankerite) ± magnetite ± ilmenite, iii) chlorite + muscovite + quartz + albite + ilmenite ± siderite ± magnetite. Micas have elevated barium contents (2.2 to 5.5 wt. % BaO in phlogopite, 2.6 to 4.6 wt. % BaO in muscovite) and represent the dominant carrier of this element in the rock. In the case that mica is absent in the rock, barium is bound in barian feldspar. When content of quartz in these greenschists is high, they pass into quartzite. Three types of sulfide ore were found in the Měděná Adit: A) banded copper ore in biotite-chlorite greenschist, which is formed dominantly by disseminated pyrite and pyrrhotite, accompanied by a small amount of chalcopyrite (the ore contains approx. 0.7 wt.% Cu), B) disseminated copper mineralization in quartz-rich bands or quartzite intercalations in chlorite greenschist, consisting mainly of pyrrhotite, less voluminous pyrite, and small amounts of chalcopyrite and galena (the ore contains approx. 0.3 wt.% Cu, the lead content is highly variable, up to 0.15 wt.% Pb), C) vein-like copper ore in greenschist with chalcopyrite dominating over pyrrhotite and pyrite (the ore has a very high copper content, 13.6 and 24.7 wt.% Cu in two analyzed samples). With its mineral composition, structural features and the character of the ore-bearing rocks, disseminated copper mineralization is similar to the Cyprus-type ores (so-called Cu-pyrite ores). The vein copper mineralization is probably a result of copper remobilization during regional metamorphism.

Spatial and Temporal Variability of Groundwater Quality Parameters in the Bauru Aquifer System (São Paulo State, Brazil)

Chemical substances can be harmful to humans when present in water at concentrations above the limits permitted by legislation. The present study analyzes the spatial-temporal variability of barium, chromium, nitrate and vanadium concentrations in groundwaters of the Bauru Aquifer System (BAS). For this purpose, triennial water-quality monitoring data (2016-2018) were acquired from CETESB (São Paulo Environmental Company). Descriptive statistical methods and geostatistical techniques (kriging) were applied. Results attest the spatial dependence of the water-quality parameters along time. Variograms indicate spatial determination coefficients (R²) between 0.435 and 0.961. The municipality of Presidente Prudente has the worst scenario, with estimates chromium and vanadium above the Maximum Allowed Values (MAV). The fact that most of licensed wells exploit water for urban supply makes the results worrying and shows up that public agencies must take some actions to decrease these concentrations.