High Concentrations Of Mg Research Articles

Microstructure of cementitious materials under the coupling effects of Cl− and Mg2+ in a marine tidal environment

To reveal the deterioration mechanism of cementitious materials serving in the marine tidal environment, this study investigates the microstructures of cementitious materials under the coupling effects of Cl− and Mg2+. This study mainly analyzes the phase composition, pore structure distribution, and micromorphology of the hardened cementitious materials with 30 % fly ash (FA), 30 % ground granulated blast furnace slag (GGBS), or a combination of 15 % FA and 15 % GGBS under different Mg2+ concentrations. The effects of Mg2+ concentration and mineral admixture type on chemically bound chloride ions and their microstructures are investigated. The results show that a large amount of Friedel’s salt is formed under the coupling effects of 0.6 mol/l Cl− and 0.1 mol/l Mg2+. A corrosive solution with a high concentration of Mg2+ is not conducive to the forming of Friedel’s salt. In a Cl− or Cl−-Mg2+ environment, GGBS can chemically bind more chloride ions than FA. With the increase of Mg2+ concentration, more pores and cracks appear on the sample surface. In a Cl−-Mg2+ corrosive solution, cementitious materials with mineral admixtures are more porous than pure cementitious materials. Cementitious materials hardened with GGBS are more porous than those materials hardened with FA. Thus, GGBS is more conducive to improving the materials’ resistance to chloride ions than FA.

Study of Microstructure and Corrosion Behavior of Cast Zn–Al–Mg Alloys

Zn-based alloys have found increasing interest as orthopedic biodegradable implantable materials, hence it was the aim of this work to investigate the microstructure and corrosion behavior of Zn–0.5Al–xMg cast alloys with different Mg additions in simulated body fluid (SBF). The cast samples were prepared using a simple stir casting method and the molten alloys were poured in a cast iron mold. The SEM results showed that adding Mg greatly influenced the microstructure of the Zn-based alloys where the degree of fineness of the microstructure increased with a rise in the Mg content. Moreover, polarization measurements revealed that the Zn–0.5Al–0.6Mg alloy attained the lowest degradation rate of 0.33 mm/year as compared to the other investigated alloys which complies the requirements of ideal corrosion rates for biodegradable bone implants. This corrosion rate helps the implantable metal alloy to last in the body until healing of the bone tissue proceeds. The fine structure and uniform distribution of Aluminum oxide and MgZn2 intermetallic phases along the grain boundaries were most likely the main factors in the superior corrosion stability of the Zn–0.5Al–0.6Mg alloy in SBF. However, higher concentrations of Mg (1 wt%) lowered the corrosion resistance of the Zn–Al–Mg alloy which was attributed to the accelerated galvanic corrosion between Zn and Mg2 Zn11 phases and the inhomogeneous distribution of corrosion products on the alloy surface due to the increased grain size and the coarse structure of the Zn alloy.

Impact of amino acids as performance-controlling additives on the hydration of reactive MgO

Since reactive magnesia (MgO) is produced at a lower temperature than CaO and is capable of sequestering significant quantities of CO2, it is considered to be a technically superior and more sustainable alternative to Portland cement. To obtain maximum carbonation and associated high strength, a variety of additives are investigated for MgO. Using amino acids as an additive is a new concept to control the polymorphism of carbonates. As the hydration of magnesia plays an important role in magnesia carbonation, this study investigates the impact of amino acids (i.e. L-arginine (L-Arg) and L-aspartic (L-Asp)) on the hydration of magnesia. Subsequent tests, including X-ray diffraction (XRD), pH tests, inductively coupled plasma optical emission spectrometry (ICP-OES), thermogravimetry (TG) - differential thermogravimetry (DTG), and scanning electron microscopy-Energy-dispersive X-ray spectroscopy (SEM-EDX) were conducted after the measurement of their strength development. The results revealed that magnesia hydrated with/without amino acids only formed brucite (Mg(OH)2) as the hydration product. A lower hydration degree was observed in the hydrated composites with the presence of amino acids, regardless of the type of amino acids. Specifically, the use of L-Asp not only delayed the hydration of MgO but also reduced the amount of brucite. The increasing amorphousness of brucite with increasing L-Asp concentration was also observed, compared to the control batch. Additionally, Mg2+ concentration was increased with the addition of L-Asp, allowing the blends to absorb more CO2 with a higher concentration of Mg2+.

DIFFERENTIATING TOURMALINE SPECIES VIA CHEMISTRY AND REFLECTANCE SPECTROSCOPY AT THE GIANT COPPER PORPHYRY DEPOSIT AND ASSOCIATED TOURMALINE BRECCIA PIPES: TESTING TOURMALINE AS A MINERAL VECTOR

Abstract The A.M. breccia is part of the Giant Copper porphyry deposit in southern British Columbia. It is the only well-defined zoned tourmaline breccia pipe in the Canadian Cordillera. Tourmaline is a common alteration mineral within the A.M. breccia and is spatially associated with Cu mineralization. Observed changes in tourmaline chemistry range from alkali (schorlitic-dravitic) to calcic (feruvitic-uvitic). Tourmaline subspecies vary based on their spatial location within the A.M. breccia. Tourmaline outside of the pipe contains higher concentrations of Mg, whereas tourmaline preferentially incorporates Fe within the pipe. These chemical variations are indistinguishable in hand specimens. Spectral reflectance data were collected from 587 tourmaline grains to determine if discerning chemical changes in tourmaline can be made field-based and thus more cost-effective. Spectral reflectance differentiates tourmaline associated with mineralization and breccia textures from tourmaline occurring distal to the pipe contact or within barren tourmaline breccia pipes. Fe-rich tourmaline within the A.M. breccia shows spectral characteristics of end-member schorl (Fe-rich) spectra. Tourmaline distal to the A.M. breccia and within barren pipes demonstrates spectra of end-member dravite (Mg-rich). This grouping suggests that tourmaline subspecies can be inferred by spectral reflectance, enhancing the efficiency of tourmaline as a mineral vector. Tourmaline was also identified via airborne spectral surveys. However, the airborne spectral survey did not identify the end-member spectral properties identified by in situ analysis. Airborne spectral surveys can rapidly identify tourmaline breccia pipe exposures and expedite early stages of exploration in ore districts where tourmaline is a known gangue mineral.

Fabrication of highly positively charged nanofiltration membranes by novel interfacial polymerization: Accelerating Mg2+ removal and Li+ enrichment

Li+, a vital green energy source, is mainly extracted from salt lakes, which also contain high concentration of Mg2+. Therefore, there is an imminent need for separation of Li+ and Mg2+. Recent innovations highlight the great potential of positively charged nanofiltration (NF) membranes for separating Mg2+ and Li+. Typically, positively charged NF membranes are prepared by the interfacial polymerization approach, where the most commonly applied aqueous phase monomer is polyethyleneimine (PEI). In this work, a new class of polyallylamine (PAA)-based NF membrane with a high density of positive charge, was developed to achieve high perm-selectivity for separating Mg2+ and Li+. The results indicated that the abundant primary amine (-NH2) groups on the PAA molecular chain endowed the NF membrane with a highly hydrophilic and positively charged polyamide layer. The resulting NF membrane exhibited superior Mg2+/Li+ separation ability with a high separation factor SMg2+/Li+ of 82.8 and a water permeance of 7.39 L/(m2hbar). It is also noteworthy that the SMg2+/Li+ value is more than 4 times higher than that of the previously reported PEI-based membrane. Moreover, our work also provides a new potential candidate for the future development of positive charged NF membranes.

Antibacterial Potential Analysis of Novel α-Helix Peptides in the Chinese Wolf Spider Lycosa sinensis.

The spider Lycosa sinensis represents a burrowing wolf spider (family Lycosidae) widely distributed in the cotton region of northern China, whose venom is rich in various bioactive peptides. In previous study, we used a combination strategy of peptidomic and transcriptomic analyses to systematically screen and identify potential antimicrobial peptides (AMPs) in Lycosa sinensis venom that matched the α-helix structures. In this work, the three peptides (LS-AMP-E1, LS-AMP-F1, and LS-AMP-G1) were subjected to sequence analysis of the physicochemical properties and helical wheel projection, and then six common clinical pathogenic bacteria (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) with multiple drug-resistance were isolated and cultured for the evaluation and analysis of antimicrobial activity of these peptides. The results showed that two peptides (LS-AMP-E1 and LS-AMP-F1) had different inhibitory activity against six clinical drug-resistant bacteria; they can effectively inhibit the formation of biofilm and have no obvious hemolytic effect. Moreover, both LS-AMP-E1 and LS-AMP-F1 exhibited varying degrees of synergistic therapeutic effects with traditional antibiotics (azithromycin, erythromycin, and doxycycline), significantly reducing the working concentration of antibiotics and AMPs. In terms of antimicrobial mechanisms, LS-AMP-E1 and LS-AMP-F1 destroyed the integrity of bacterial cell membranes in a short period of time and completely inhibited bacterial growth within 10 min of action. Meanwhile, high concentrations of Mg2+ effectively reduced the antibacterial activity of LS-AMP-E1 and LS-AMP-F1. Together, it suggested that the two peptides interact directly on bacterial cell membranes. Taken together, bioinformatic and functional analyses in the present work sheds light on the structure-function relationships of LS-AMPs, and facilitates the discovery and clinical application of novel AMPs.

Adsorption of Hydrated Pr3+ and NH4+/Mg2+ Ions onto the (001) Surface of Montmorillonite: A DFT Analysis with Experimental Verification

Montmorillonite is a major mineral present in ion-adsorption rare earth ores, and the microscopic adsorption states of rare earth ions on its surface are of a great significance for the efficient exploitation of ion-adsorption rare earth ores. In this article, density functional theory calculations were used to investigate the adsorption mechanisms and bonding characteristics of hydrated Pr, Mg and NH4 ions on the (001) surface of montmorillonite. Pr3+ exhibited a directed tendency geometry with Pr(H2O)103+, which was adsorbed onto montmorillonite by hydrogen bonding with an adsorption energy of −1182 kJ/mol, and one coordinated H2O ligand was separated from the first hydration layer of Pr. Both hydrated Mg and NH4 ions were adsorbed onto the montmorillonite surface through hydrogen bonds, and the adsorption energies were −206 and −188 kJ/mol, respectively, indicating that the adsorption stability of the hydrated Mg ion was slightly higher than that of the hydrated NH4 ion, but both were lower than that of hydrated Pr (−1182 kJ/mol). Hence, higher concentrations of Mg and NH4 ions than rare earth ions would be necessary in the leaching process of ion-adsorption rare earth ores. Additionally, desorption experiments revealed that the recovery of Pr3+ by Mg2+ with a concentration of 38 mmol/L is 80%, while it is only 65% with the same concentration of NH4+, and the concentrations of Mg2+ and NH4+ were much higher than that of Pr3+ in lixivium, which is consistent with the DFT calculations.

Characterization of macro and micro-minerals in cassava leaves from genotypes planted in three different agroecological locations in Nigeria

Diversity in the mineral composition of cassava leaves bred in sub-Saharan Africa has not been fully investigated. This study characterized macro and micro-minerals in 400 genotypes of Cassava leaves planted in three different agroecological environments in Nigeria. Laboratory analysis of the leaves was done using an Inductively Coupled Optical Emission Spectrometer. Across all three locations sampled in this study, the iron content ranged from 43 to 660 mg/kg, zinc from 16 to 440 mg/kg, Manganese 16–61mg/kg, Copper 0.7–14 mg/kg, Aluminum 5.3–630 mg/kg. Among the macro elements, Calcium ranged from 3600 to 17600 mg/kg, Magnesium 1760–6500 mg/kg, Sodium 0.4–720 mg/kg, Potassium 3100–27000 mg/kg. When the location effect was tested, there was a significant difference among the genotypes for all elements. Cluster analysis resulted in five clusters containing 187, 147, 60, 2, and 4 genotypes, respectively. Cluster 2 contained eight varieties (01/0046, 94/0020, 93/0098, 88/112-7(3X), I00/0017, 91/00417, I00/0017, 88/112-7(3X)) that possessed the highest mineral compositions in Fe, Al, Ti, Na, K, S, Mn, and B, respectively. Genotypes 93/0681(4X), 92/0430, and 95/0460 in cluster 3 had the highest concentrations of Mg, Na, and Zn, respectively. The correlation results showed a notable positive relationship among iron with zinc, copper, aluminum, and titanium (r = 0.33, 0.39, 0.48, and 0.56, respectively), zinc with nickel, titanium, and sulphur (r = 0.52, 0.3,2 and 0.51, respectively) while calcium negatively correlated with potassium (r = ‒ 0.31), phosphorus (r = ‒0.41). This study provides evidence that genotypic diversity exists for mineral composition in cassava leaves and, therefore, can be exploited for genetic improvement by breeders seeking solutions to reduce persistent mineral deficiencies in sub-Saharan Africa.

Electronic and Optical Properties of Rocksalt Mg1-xZnxO and Wurtzite Zn1-xMgxO with Varied Concentrations of Magnesium and Zinc.

The structural, electronic and optical properties of rocksalt Mg1-xZnxO and wurtzite Zn1-xMgxO with the concentration of Zn and Mg varying from 0.125 to 0.875 were investigated using density functional theory (DFT), DFT+U, linear response theory and the Bethe-Salpeter equation. According to the experimental band gap for varied concentrations of magnesium and zinc, modeling the supercell was utilized for the varied concentrations of Mg/Zn/O compounds in order to not only avoid constructing the complicated interface systems that are observed in the experiments but also take into account the excitonic effects that usually require huge computational resources. From the calculated density of states, the Zn states are highly related to the edge of the conduction band minimum and responsible for the width of bandgap. In addition, the contribution of Zn-d states is below expectations as they are located away from the VBM. As for the optical response, an increase in Zn concentration would cause a red-shifted spectrum, on the whole. In contrast, the higher concentration of Mg also triggers the blue-shift of the optical spectrum. In addition, anisotropic properties could be found in the spectrum with consideration of the excitonic effects, whereas there is no apparent difference in optical response based on linear response theory. In addition, the optical features of this work reflect the characteristic peaks of the literature around the absorption onset.

The Mineral Composition of Bone Marrow, Plasma, Bones and the First Antlers of Farmed Fallow Deer.

Simple SummaryYoung cervids build their skeleton during the growth of their first antlers, which is why this is a period of great demand for minerals. The mineral compositions of bone marrow, plasma, bones, and antlers are good indicators of changes that occur in the metabolism of farmed fallow deer. The aim of the study was to analyze the concentrations of 21 mineral elements (bulk elements: Ca, P, Mg, K, Na; trace elements: Li, Cr, Mn, Co, Cu, Zn, Se, Mo; and toxic elements: Be, Al, As, Cd, Sb, Ba, Pb, Ni) in the aforementioned tissues. The highest content was characterized by bulk elements whose content increased in bone, bone marrow and antlers according to the following series: Ca > P > Na > Mg > K. The plasma was characterized by a different concentration of individual elements in the order of Na > K > Ca > P > Mg. The analysis of trace and toxic elements indicated that higher levels were recorded in bone tissues (in antlers and then in bones). It is worth emphasizing that the research indicates a negative correlation between Ca and Cd and between Ca and Pb and between P and Pb in tissues.An adequate supply of essential nutrients is particularly important during the skeletal growth and development of young deer, especially in males, who build new antlers each year. The aim of the research was to analyze the levels of 21 mineral elements (including the bulk elements: Ca, P, Mg, K, Na; trace elements: Li, Cr, Mn, Co, Cu, Zn, Se, Mo; and toxic elements: Be, Al, As, Cd, Sb, Ba, Pb, Ni) in the bone marrow, plasma, bones, and first antlers of farmed fallow deer (Dama dama). The mineral compositions of tissues were analyzed using inductively coupled plasma mass spectrometry. Higher concentrations of Ca, P, Mg, Cr, Zn, Se, Al, Ba and Ni were found in bone marrow than in plasma. The highest concentrations of Ca, P and Ba were recorded in fallow deer bone, while the highest concentrations of Mg, K, Na, Li, Cr, Mn, Co, Cu, Zn, Se, Mo, Be, Al, As, Sb, Pb and Ni were found in the antlers. Moreover, the research showed a significant negative relationship between Ca and Cd, and between Ca and Pb, and P and Pb (rS = −0.70, rS = −0.80, and rS = −0.66, respectively; p < 0.05) in the tissues.

Insight into leaching of rare earth and aluminum from ion adsorption type rare earth ore: Adsorption and desorption

Clay minerals are inferred to be the primary host materials for ion-exchangeable rare earth in ion adsorption type rare earth ore (IAREO). During the rare earth leaching process, the adsorption and desorption reactions of the cations controlling the leaching process continue to occur at the clay minerals-leaching agent solution interface. In order to understand the leaching mechanism and behavior of rare earth and co-leached aluminum, adsorption, competitive adsorption, and desorption experiments were carried out using kaolin as a typical clay mineral. The powerful electrostatic attraction and concentration driving forces facilitate the adsorption of cations. The adsorption ability and competitive adsorption ability of cations depend on their charge, hydration radius, and hydrolysis properties, and decrease in the order of La3+, Y3+, Al3+, Mg2+, and NH4+. The desorption of rare earth and aluminum is positively affected by the concentration-driving force exerted by high concentrations of Mg2+ and NH4+, with the order of the desorption ability being opposite to the adsorption ability. However, unspecified interactions between clay mineral particles enhanced by high-concentration desorbents, especially by Mg2+ than NH4+, will adversely affect desorption reactions, which result in lower desorption efficiencies of rare earth and aluminum obtained with magnesium sulfate compared to those obtained with ammonium sulfate at high concentrations. Solid-phase Al(OH)3 generated at a high peak aluminum concentration leads to a considerably delayed aluminum efflux, thereby partially separating the rare earth from aluminum during the actual column leaching process. To advance the mining technology of IAREO by selectively improving the rare earth leaching efficiency with minimal leaching agent consumption, higher charged cations with concentrations limited to suitable levels should be preferred as leaching agents.

Seasonal Differences in the Hydrochemical Characteristics of Karst Wetlands and the Associated Mechanisms in Huixian, China

The present study aimed to identify the seasonal changes in the hydrochemical characteristics of the Huixian karst wetland and the underlying mechanism. Conventional ions and isotopes of 130 groundwater samples collected during the wet and dry seasons were analyzed. The hydrochemical characteristics of groundwater in the Huixian karst wetland were clarified using mathematical statistics and hydrochemical methods, including Durov diagrams, ionic ratios, Gibbs diagrams, and H and O isotopes. The hydrochemical evolution and sources of major ions in the Huixian karst wetland were also investigated. The results showed that cations and anions in groundwater in the study area were dominated by Ca2+ and HCO3−, respectively, sourced mainly from calcite weathering. The ions of some groundwater samples were regulated by weathering of dolomite, dolomitic limestone, and pyrite, resulting in relatively high concentrations of Mg2+ and SO42−. K+, Na+, SO42−, NO3−, and Cl− in groundwater originated from precipitation, Na+ and Cl− originated from domestic sewage, K+ was related to the application of potassium fertilizer in agriculture, and NO3− mainly originated from chemical fertilizer. Groundwater ions were primarily controlled by rock weathering, followed by evaporative concentration. The sources of major ions were dependent on the dissolution and precipitation of carbonate rock, as well as the chemical weathering of silicate rock and evaporite. Samples from the various water sources were scattered on both sides of the local meteoric water line (δD = 3.13δ18O − 13.9), which indicated isotopic composition was affected by evaporation and precipitation.

Dolomitization Mechanism in the Chorgali Formation (Eocene), Pakistan: Evidences from Field observations, Petrography, Mineralogical and SEM analysis

The subject of dolomite formation has always put researchers in the challenge. In this study, the origin of the dolomites of the Chorgali Formation near Chorgali Pass was explored through field observation, petrographic characteristics, mineralogical and geochemical analysis. Analytical analyses used in the present studies include XRD, SEM-EDS, and stable isotopes studies. The dolomites were categorized into three major genetic types based on their textural and structural features showing their distinct origins. These dolomites are named fine crystalline dolomite (Df), medium crystalline dolomite (Dm), and coarse crystalline dolomite (Dc). The analytical approaches linked with field observations and petrographic examinations identified that; the first type of dolomites (i.e., Df) is related to the early stage of diagenesis and contain the presence of mineral dolomite (40%), gypsum (27%), quartz (17%) and albite (16%) and are low stochiometric low ordered in character as recognized by XRD results. The SEM-EDS analysis identified low Mg, Ca, O, Na, Si, and Fe concentrations. Further, the stable isotopes (δ18O) values for Df (i.e., -5.95 to -396‰V-PDB) are less depleted. Moreover, Dm and Dc revealed 100% mineral dolomite and are stochiometric ordered dolomites. High concentrations of Mg, Ca and O are observed in Dm and Dc respectively. Stable isotopes (δ18O) result in exhibiting highly depleted values for Dm (-7.947‰V-PDB) and Dc (-9.227 to -8.302‰V-PDB) showing its formation with the elevated temperature at depth. In addition, δ13C values of Df, Dm, and Dc lie in the range of the original marine signature of Eocene times.

HwMR is a novel magnesium-associated protein

Microbial rhodopsins (MRho) are vital proteins in Haloarchaea for solar light sensing in extreme living environments. Among them, Haloquadratum walsbyi (Hw) is a species known to survive high MgCl2 concentrations, with a total of three MRhos identified, including a high-acid-tolerance light-driven proton outward pump, HwBR, a chloride-insensitive chloride pump, HwHR, and a functionally unknown HwMR. Here, we showed that HwMR is the sole magnesium-sensitive MRho among all tested MRho proteins from Haloarchaea. We identified at least D84 as one of the key residues mediating such magnesium ion association in HwMR. Sequence analysis and molecular modeling suggested HwMR to have an extra H8 helix in the cytosolic region like those in signal-transduction-type MRho of deltarhodopsin-3 (dR-3) and Anabaena sensory rhodopsin (ASR). Further, HwMR showed a distinctly prolonged M-state formation under a high concentration of Mg2+. On the other hand, an H8 helix truncated mutant preserved photocycle kinetics like the wild type, but it led to missing M-state structure. Our findings clearly suggested not only that HwMR is a novel Mg2+-associated protein but that the association with both Mg2+ and the H8 domain stabilizes M-state formation in HwMR. We conclude that Mg2+ association and H8 are crucial in stabilizing HwMR M state, which is a well-known photoreceptor signaling state.

Structural and Functional Characterization of the Holliday Junction Resolvase RuvC from Deinococcus radiodurans.

Holliday junctions (HJs) are four-way DNA structures, which are an important intermediate in the process of homologous recombination. In most bacteria, HJs are cleaved by specific nucleases called RuvC resolvases at the end of homologous recombination. Deinococcus radiodurans is an extraordinary radiation-resistant bacterium and is known as an ideal model organism for elucidating DNA repair processes. Here, we described the biochemical properties and the crystal structure of RuvC from D. radiodurans (DrRuvC). DrRuvC exhibited an RNase H fold that belonged to the retroviral integrase family. Among many DNA substrates, DrRuvC specifically bound to HJ DNA and cleaved it. In particular, Mn2+ was the preferred bivalent metal co-factor for HJ cleavage, whereas high concentrations of Mg2+ inhibited the binding of DrRuvC to HJ. In addition, DrRuvC was crystallized and the crystals diffracted to 1.6 Å. The crystal structure of DrRuvC revealed essential amino acid sites for cleavage and binding activities, indicating that DrRuvC was a typical resolvase with a characteristic choice for metal co-factor.

Glucose-mediated one-pot hydrothermal synthesis of hollow magnesium oxide-zinc oxide (MgO-ZnO) microspheres with enhanced natural sunlight photocatalytic activity.

Glucose -mediated one-pot hydrothermal method has been utilized to synthesize hollow spherical MgO-ZnO (xMgO-(1-x)ZnO, x = 0, 0.2, 0.4, 0.6) microstructures which are highly efficient in high-energy ultraviolet (UV) region of natural sunlight. In this process, glucose formed roundish spheres, and simultaneously metal precursors were coated on that spheres during the hydrothermal reaction. X-ray diffraction analysis (XRD) supports the formation of highly crystalline wurtzite structure of MgO-ZnO for Mg loading less than 20%. Higher concentration of Mg produces wurtzite hexagonal ZnO and cubic MgO in the composites. The widening in band gap energy of synthesized MgO-ZnO microspheres compared to ZnO was analyzed by UV-visible diffuse reflectance spectroscopy (UV-DRS) result. Brunauer-Emmett-Teller (BET) surface area analysis showed that with the increase in Mg loading, the specific surface area increases up to 14.27 times as compared to pristine ZnO. The synthesized catalysts were used as an efficient photocatalyst towards the degradation of rhodamine B (RhB), methylene blue (MB), and phenol under natural solar irradiation. Results illustrated that MB and RhB dye solutions were 100% degraded by 0.6 MgO-ZnO in 100min and 150min, respectively, whereas pure ZnO samples showed only 65% and 79% degradation. Also, for phenol solution, 0.6 MgO-ZnO showed enhanced degradation efficiency of 72% in 240min in comparison with 58% degradation shown by ZnO. Additionally, the MgO-ZnO catalysts were stable and showed excellent degradation efficiency up to four consecutive cycles which open a new direction towards potential industrial applications. Hence, the novelty of the current work is to prepare hollow MgO-ZnO microspheres by a single-step hydrothermal process where separate carbon template preparation is not required and to utilize these hollow microspheres as a highly efficient photocatalyst by harnessing the high-energy UV fraction of natural sunlight.

Prebiotic Environments with Mg2+ and Thiophilic Metal Ions Increase the Thermal Stability of Cysteine and Non-cysteine Peptides.

Wet-dry cycles driven by heating to high temperatures are frequently invoked for the prebiotic synthesis of peptides. Similarly, iron-sulfur clusters are often cited as an example of an ancient catalyst that helped prune early chemical systems into metabolic-like pathways. Because extant iron-sulfur clusters are metallocofactors of protein enzymes and nearly ubiquitous across biology, a reasonable hypothesis is that prebiotic iron-sulfur peptides formed on the early Earth. However, iron-sulfur clusters are coordinated by multiple cysteine residues, and the stability of cysteines to the heat steps of wet-dry cycles has not been determined. It, therefore, has remained unclear if the peptides needed to stabilize the formation of iron-sulfur clusters could have formed. If not, then iron-sulfur-dependent activity may have emerged later, when milder, more biological-like peptide synthesis machinery took hold. Here, we report the thermal stability of cysteine-containing peptides. We show that temperatures of 150 °C lead to the rapid degradation of cysteinyl peptides. However, the presence of Mg2+ at environmentally reasonable concentrations leads to significant protection. Thiophilic metal ions also protect against degradation at 150 °C but require concentrations not frequently observed in the environment. Nevertheless, cysteine-containing peptides are stable at lower, prebiotically plausible temperatures in seawater, carbonate lake, and ferrous lake conditions. The data are consistent with the persistence of cysteine-containing peptides on the early Earth in environments rich in metal ions. High concentrations of Mg2+ are common intra- and extra-cellularly, suggesting that the protection afforded by Mg2+ may reflect conditions that were present on the prebiotic Earth.

Effects of short term acidogenic diet feeding on metabolic parameters of dairy cows with induced subclinical hypocalcemia

The objective of was to evaluate whether the provision of an acidogenic diet in late gestation influences the metabolism of cows with experimentally induced subclinical hypocalcemia. Nine multiparous Holstein cows were divided into 3 groups according to the duration of supply of the acidogenic diet: G0 = without acidogenic diet; G9 = nine days and G15 = fifteen days. All animals underwent an experimental induction of subclinical hypocalcemia for 6 hours, performed after the last day of feeding with the diet. Urine samples were collected weekly to evaluate the effectiveness of the diet and blood samples were collected performed one day (-1) and immediately (0) before the induction, every hour until 6 h after the induction and at the end of 72 hours for the evaluation of metabolic parameters. During INDUCTION, G15 had the lowest concentration of CaT, globulins, TP, HCO¬¬ 3, pCO2, K and the highest concentration of creatinine (P &lt; 0.05); G9 and G15 had the lowest concentration of iCa and higher concentration of Mg (P &lt;0.05). In the POST-INDUCTION period, G15 again had the lowest concentration of globulins, TP, HCO¬- 3 and lowest serum pH, in addition to having the highest concentration of creatinine, glucose, and Na (P &lt;0.05). G9 and G15 had the lowest CaT and K concentration and the highest Mg (P &lt; 0.05) in that period. Provision of 15 days of an acidogenic diet to cows with induced hypocalcemia modulated other parameters besides calcium, demonstrated may not be suitable for animals.

Variation of Macro- and Microelements, and Trace Metals in Spring Wheat Genetic Resources in Siberia.

Western Siberia is one of the major spring wheat regions of Russia, cultivating over 7 Mha. The objective of the study was to evaluate the variation of macro- and microelements, and of trace metals in four distinct groups of genetic resources: primary synthetics from CIMMYT (37 entries), primary synthetics from Japan (8), US hard red spring wheat cultivars (14), and material from the Kazakhstan–Siberian Network on Spring Wheat Improvement (KASIB) (74). The experiment was conducted at Omsk State Agrarian University, using a random complete block design with four replicates in 2017 and 2018. Concentrations of 15 elements were included in the analysis: macroelements, Ca, K, Mg, P, and S; microelements, Fe, Cu, Mn, and Zn; toxic trace elements, Cd, Co, Ni; and trace elements, Mo, Rb, and Sr. Protein content was found to be positively correlated with the concentrations of 11 of the elements in one or both years. Multiple regression was used to adjust the concentration of each element, based on significant correlations with agronomic traits and macroelements. All 15 elements were evaluated for their suitability for genetic enhancement, considering phenotypic variation, their share of the genetic component in this variation, as well as the dependence of the element concentration on other traits. Three trace elements (Sr, Mo, and Co) were identified as traits that were relatively easy to enhance through breeding. These were followed by Ca, Cd, Rb, and K. The important biofortification elements Mn and Zn were among the traits that were difficult to enhance genetically. The CIMMYT and Japanese synthetics had significantly higher concentrations of K and Sr, compared to the local check. The Japanese synthetics also had the highest concentrations of Ca, S, Cd, and Mo. The US cultivars had concentrations of Ca as high as the Japanese synthetics, and the highest concentrations of Mg and Fe. KASIB’s germplasm had near-average values for most elements. Superior germplasm, with high macro- and microelement concentrations and low trace-element concentrations, was found in all groups of material included.

In situ LA-ICP-MS trace element analysis of magnetite as a vector towards mineral exploration: A comparative case study of Fe-skarn deposits from SW Iberia (Ossa-Morena Zone)

The Azenhas and Alvito Fe-deposits are located at SW of the Iberian Variscan belt, in a wide Fe-Zn ore district (Montemor-Ficalho Belt), part of the Ossa-Morena Zone. Both deposits are dominantly composed of magnetite ores that display distinct ore formation processes and, at the Azenhas deposit, massive magnetite ores are mainly hosted in amphibolites (Middle Cambrian – Ordovician), with a genesis arguably associated with metamorphic-metasomatic reactions promoted by fluid circulation through several thrust faults that led to and expressive tectonic pilling. Contrastingly, the Alvito massive magnetite ores are formed by the emplacement of a gabbro-dioritic suite in contact with calcite-dolomite marbles, constituting a typical calcic exoskarn Fe-skarn deposit. Primary and secondary magnetite were identified and characterized, and further selected for in situ laser ablation coupled inductively mass spectroscopy (LA-ICP-MS) trace element analysis. Results show that primary magnetite (Mag I) from the Azenhas deposit is discriminated by higher concentrations of Mg, Cr, Mn, Zn, Co, and Sn, whereas secondary magnetite (Mag II) is depleted in most trace elements, although displaying relatively higher concentrations of V, Ga, Mo, and Pb. The application of TMg-Mag geothermometer reinforced the discriminatory indexes, with Mag I displaying higher-temperature estimations (ca. 770 °C) when compared to Mag II (ca. 420 °C), thus suggesting that primary ores are associated to higher temperature processes than previously assumed.Characterization of the ores from Alvito deposit revealed primary magnetite characterized by abundant ilmenite and Al-spinel oxy-exsolutions which led to high measured Al concentrations in magnetite. The trace element content indicates high-temperature hydrothermal magnetite, underlining the contribution of hot hydrothermal fluids from the igneous body emplacement, also supported by the TMg-Mag geothermometer (ca. 685 °C). The anomalous presence of Co (max. 156 ppm) and Ni (max. 100 ppm) concentrations in Mag I from Alvito, along with pentlandite-magnetite assemblages, suggest that prone conditions were sustained for the development of Ni-bearing ores and that magnetite composition could be an interesting geochemical proxy for the exploration of such mineralization.The Mn + Al versus Ti + V discriminant diagram shows that primary ores from both deposits plot in the skarn field. The combination of magnetite analyses with whole-rock geochemistry and field geology, allowed us to define criteria that can be applied in the discrimination of Fe-deposits and contribute to improve the geological models of the studied ore deposits, thus beneficiating future exploration in SW Iberia.