Mg In Solution Research Articles

In situ High-Energy Synchrotron X-ray Studies in Thermodynamics of Mg-In-Ti Hydrogen Storage System

Achieving dual regulation of the kinetics and thermodynamics of MgH 2 is essential for the practical applications. In this study, a novel nanocomposite (In@Ti-MX) architected from single-/few-layered Ti 3 C 2 MXenes and ultradispersed indium nanoparticles was prepared by a bottom-up self-assembly strategy and introduced into MgH 2 to solve the above-mentioned problems. The MgH 2 +In@Ti-MX composites demonstrate excellent hydrogen storage performance: The resultant In@Ti-MX demonstrated a positive effect on the hydrogen storage performance of MgH 2 /Mg: the dehydrogenated rate of MgH 2 +15 wt%In@Ti-MX reached the maximum at 330 °C, which was 47 °C lower than that of commercial MgH 2 ; The hydrogenation enthalpy of the dehydrided MgH 2 +15 wt%In@Ti-MX and MgH 2 +25 wt%In@Ti-MX were determined to be −66.2 ± 1.1 and −61.7 ± 1.4 kJ·mol −1 H 2 . In situ high-energy synchrotron x-ray diffraction technique together with other microstructure analyses revealed that synergistic effects from Ti 3 C 2 MXenes and In nanoparticles (NPs) contributed to the improved kinetics and thermodynamics of MgH 2 (Mg): Ti/TiH 2 derived from Ti 3 C 2 MXenes accelerated the dissociation and recombination of hydrogen molecule/atoms, while In NPs reduced the thermodynamic stability of MgH 2 by forming the Mg-In solution. Such a strategy of using dual-active hybrid structures to modify MgH 2 /Mg provides a new insight for tuning both the hydrogen storage kinetics and thermodynamics of Mg-based hydrides.

Effect of alpha-lipoic acid on rat kidney and liver microsomes subjected to oxidative stress induced by ascorbate-Fe++

Metabolic changes during kidney and liver disease can induce increased production of oxygen radicals that play an important role in the progression of kidney and liver damage and in the appearance of important comorbidities. In the study reported here, the effect of alpha-lipoic acid (ALA) on the chemiluminescence (CL) and TBARS determination of microsomes isolated from rat kidney and liver was analyzed. Oxidative stress in microsomes was induced by subjecting samples (1 mg of protein) to an ascorbate-Fe++-dependent (0.4 mM)-Fe++ (2.15 μM) prooxidant system at 37 °C for 120 min. Oxidative damage was quantified by two methods, TBARS and CL: CL was determined using a Packard 1900 TR liquid scintillation counter (Meriden CT, USA). CL was expressed as cpm (counts per minute) was read every 10 minutes to establish the course of peroxidation as a function of time. Likewise, the total value of cpm (sum of the readings) was used to compare the inhibitory effect of ALA using different concentrations corresponding to 0.05; 0.15 and 0.25 μg of ALA per mg of microsomal protein. Controls were run simultaneously without the addition of ascorbate-Fe++. It was observed that the CL was lower in the kidney and liver microsomes obtained from the ALA group than in the control group (without ALA). In addition, -ALA was found to be concentration-dependent (0.05, 0.15 and 0.25 μg of ALA per mg of solution) reduced in CL, measured as total cpm. After that it was done the determination of lipid peroxidation products (Thiobarbituric Acid Reactive Substances—TBARS). TBARS were measured in the microsomal samples. Lipoperoxidation inhibition depended on the concentration of ALA in the incubation mixture. The results show that for all the concentrations tested, a protective effect on the induced oxidative damage was found. CL and TBARS level analyzes indicate that ALA may act as an antioxidant protecting rat kidney and liver microsomes from lipoperoxidative damage.

An Mg-MOFs based multifunctional medicine for the treatment of osteoporotic pain

Bone pain is the primary problem for patients with osteoporosis. Ketoprofen is clinically used to treat osteoporotic pain, while long-term oral administration of ketoprofen can cause some side effects. In addition, osteoporosis is also accompanied by bone mass loss and inflammation. In this study, we designed a multifunctional drug (Ket@Mg-MOF-74) adopted Mg-MOF-74 to load ketoprofen to treat osteoporotic pain, bone loss and inflammation comprehensively. Mg-MOF-74 was prepared, and the physicochemical characterization proved that it had excellent physical and chemical stability. Ket@Mg-MOF-74 was synthesized by post-synthetic modification method and a high loading rate of ketoprofen was confirmed. Drug release and ion release experiments indicated Ket@Mg-MOF-74 had a good controlled release of ketoprofen and Mg in solution. Cell experiments in vitro proved the compound drug could significantly reduce the expression of pain-related genes of cyclooxygenase 2 (COX2), obviously up-regulated the expression of osteogenic cytokines and remarkably down-regulated the secretion of pro-inflammatory factors. Therefore, Ket@Mg-MOF-74 is believed a promising painkiller for osteoporotic bone pain, with the function of anti-inflammatory and promoting bone formation.

NaPi-IIb Inhibition for Hyperphosphatemia in CKD Hemodialysis Patients

IntroductionChronic kidney disease (CKD) has a prevalence of 9.1% globally, and frequently results in elevated serum phosphate, increasing cardiovascular morbidity and mortality risk in hemodialysis (HD) patients. DS-2330b, an oral NaPi-IIb inhibitor, reduced intestinal phosphate absorption in preclinical studies, but its effect in patients with CKD is unknown. This 2-part, randomized, placebo- and active-controlled, single- and repeated-dose, phase 1b study evaluated safety and efficacy of DS-2330b in patients with CKD on HD.MethodsPart A, a 2-period, 2-way study, evaluated safety and pharmacokinetics of DS-2330b 250 mg in solution and tablet formulations. Part B assessed the safety of DS-2330b in solution (chosen based on results of part A) and its effect on serum phosphate. Patients were randomized to placebo 3 times daily (TID), DS-2330b 400 mg TID, DS-2330b 400 mg with sevelamer 1.6 g TID, and sevelamer 1.6 g with placebo TID for 14 days. Safety endpoints included adverse event (AE) monitoring.ResultsSix patients completed part A. Two patients experienced serious AEs considered unrelated to DS-2330b treatment. Thirty-two patients enrolled and completed part B. Serum phosphate mean change from baseline ± SD was −2.2±1.5 mg/dl versus −1.9 ± 1.1 mg/dl for DS-2330b monotherapy versus placebo. Patients receiving DS-2330b with sevelamer or sevelamer with placebo experienced the greatest serum phosphate decrease from baseline. Nine patients (28.1%) experienced ≥1 treatment-emergent AE (TEAE); 7 patients experienced drug-related TEAEs. The TEAE incidence was comparable between DS-2330b and control groups.ConclusionsDS-2330b, alone or in combination with sevelamer, was safe and well tolerated but did not demonstrate clinically meaningful efficacy in HD patients.

Hydrogeochemistry of authigenic mineral formation in Upper Jurassic sediments (the Nadym-Taz interfluve area, Arctic regions of Western Siberia)

This paper presents a novel numerical modelling approach to physicochemical evolution of water – rock interactions in Upper Jurassic sediments in the Nadym–Taz interfluve (Arctic regions of Western Siberia). The results show that the authigenic mineral formation proceeds continuously and strictly successively (kaolinite – montmorillonite – illite – mica – chlorite – albite – microcline), involving definite geochemical parameters of the medium (pH, concentrations of SiO2, Al, Na, K, Ca, Mg in solution). For example, the widely spread kaolinite cement forms in the medium with near neutral pH (on average, рH = 7.2) with silica concentration in solution 15–20 mg/dm3, while the formation of authigenic illite begins at silica concentration of 25–40 mg/dm3 and pH about 7.3–7.4. Despite rather low salinity (up to 63 g/dm3) of the investigated groundwater and long-term interaction of water with the rocks (spanning ca. 165 Ma), the equilibrium with primary (endogenous) minerals such as albite, anorthite, microcline is practically unobserved. At the same time, the groundwater is in equilibrium with mica, illite, Ca–, Na– and Mg–montmorillonites, kaolinite, more rarely with Mg–chlorite. The state of groundwater equilibrium with primary aluminosilicate minerals is always challenged by a carbonate barrier, so rocks carbonatization in various degree is observed almost everywhere.

Selectivity coefficients of K, Na, Ca, and Mg in binary exchange systems in some calcareous soils.

One of the major issues in surveying the sorption and mobility of elements is awareness of the behavior and reactions of elements in soils and their distribution coefficient (Kd) values. This study was conducted to investigate the adsorption of potassium (K), sodium (Na), calcium (Ca), and magnesium (Mg) in six calcareous soils saturated with mentioned cations. The initial equivalent fraction of K, Na, Ca, and Mg in solutions increased from 0.1 to 1 at a total electrolyte of 30meqL-1. The shape of isotherm curves and the amount of cations adsorbed varied in different binary exchange systems. The adsorption of cations increased gradually with increasing initial concentrations. The average values of Kd (Lkg-1) in different binary systems were arranged in the following order: Ca-Mg (23.4) > Mg-Na (21.5) > Mg-K (20.7) > Mg-Ca (20.1) > Ca-Na (16.0) > Ca-K (15.4) > K-Mg (5.6) > K-Na (5.0) > K-Ca (4.6) > Na-Ca (2.7) > Na-Mg (1.9) > Na-K (1.7). The average values of Gaines-Thomas selectivity coefficients of cations in different binary exchange systems followed this order: K-Ca (16.5) > K-Mg (7.8) > Ca-Mg (4.1) > Mg-Ca (3.1) > Mg-Na (2.1) > K-Na (1.7) > Mg-K (1.0) > Ca-Na (0.8) > Ca-Na (0.6) > Na-Ca (0.5) > Na-Mg (0.1) = Na-K (0.1). So, the affinity of cations for adsorption by soils followed this order: K > Ca > Mg > Na which differed from the classical lyotropic series. The high affinity of K for adsorption by soils was attributed to the presence of illite. The free cations were the most abundant species (above 90%) in all soil solutions after reaching equilibrium with initial concentrations of 3 and 30meqL-1. The saturation index (SI) values of minerals in all exchange systems were negative.

The combined influence of Mg and Ca on microstructural evolution of alumina

AbstractThe solubility limits of Ca and Mg co‐doped in alumina at 1600°C were determined by equilibrating alumina saturated with Ca and Mg. This resulted in the formation of MgAl2O4 (Mg spinel), CaO·6Al2O3 (CA6), Ca2Mg2Al28O46 (CAM‐II), and alumina grains saturated with Mg and Ca. Under these conditions, the amount of Ca and Mg in the alumina grains represents the solubility limits. The solubility limits were measured using a fully standardized wavelength dispersive spectrometer mounted on a scanning electron microscope. In the co‐doped state, the solubility limit of Ca in alumina was 32 ± 13 ppm, and the solubility limit of Mg in alumina was 210 ± 43 ppm. The presence of Ca results in an increase of the solubility limit of Mg in alumina from 132 to 210 ppm, suggesting that the increased Mg in solution results in more Mg excess at the alumina grain boundaries, thus contributing to a decreased grain‐boundary mobility by solute‐drag.

EDTA-Fe(III) Fenton-like oxidation for the degradation of malachite green

Industrial waste, urban sewage and aquaculture have led to severely increased grades of environment pollutants such as dyes, pesticides and fertilizer. The use of technologies for purifying contaminated waters can be difficult and toxic due to the anti-photolysis, anti-oxidation and anti-bio-oxidation characteristics of organic pollutants, and there is therefore a significant need for new approaches. Here, we report methods of Fenton oxidation and EDTA-Fe(III) Fenton-like oxidation which can be used to degrade malachite green (MG: a dye and antibiotic-like substance) from contaminated water. Compared with the degradation rate (59.34%) of the Fe(III)/H2O2 Fenton process, the EDTA-Fe(III) Fenton-like oxidation got a better degradation rate (92.7%) at neutral pH conditions. By conducting a series of parallel controlled experiments (changing parameters such as the reactant concentration, temperature, and pH), we report the relationships between the degradation effect and different parameters, and we fitted their pseudo first order kinetic curves. Furthermore, we repeated to adjustment of the concentrations of MG in solutions to test the cycle performance and catalytic activities of EDTA-Fe(III)/H2O2 system and it showed good repeatability in the first five rounds and all of them keep the degradation efficiencies greater than 80%. By conducting comparative spin-trapping electron paramagnetic resonance (EPR) experiments, we showed indirectly that the OH contributes to the degradation of MG. Additionally, the results of the EPR experiments showed that EDTA contributes to the generation of OH in the EDTA-Fe(III)/H2O2 Fenton-like system. By conducting total organic carbon (TOC) analysis experiments, we found that EDTA was also oxidized to some extent during the degradation of MG. In all, the findings of this work widen the range of the optimal pH values up to neutral condition for degradation of MG by use of EDTA-Fe(III) Fenton-like system. And this system could be used as one approach for the degradation of organic pollutants at neutral conditions and provide some initial information regarding EDTA-Fe(III) Fenton-like oxidations. It's significant for the expansion of the homogenous Fenton-like family and its application in the field of water treatment.

Nutrient Dynamics in Soil Solution and Wheat Response after Biomass Ash Amendments

Among the possible methods for biomass ash (BA) utilization, land application represents an important nutrient‐saving approach of BA management. The land application of BA results in an increase of soil pH, but in contrast to conventional liming, ash application on agricultural land can supply additional nutrients to soil, such as K, Mg, or P. However, due to the complex mineral phase composition of ashes, release of nutrients from the ash matrix into soil solution is not well understood. In the presented pot experiment, two agricultural soils were amended using two common types of BA (wood and straw ash) at rate 1% (w/w). During the vegetation period of spring wheat (Triticum aestivum L.), soil solution was sampled and monitored for the concentrations of Ca, K, Mg, and P. Subsequently, yield and nutrient uptake of wheat were determined. The effect of ash application on the investigated parameters differed substantially between the tested soils. Positive yield responses were found in soil with higher N content. Straw ash application increased concentrations of all monitored nutrients in soil solution but simultaneously increased plant uptake of K and P only. Wood ash increased concentrations of Ca and Mg in solution, while its effect on nutrient uptake strongly differed between soils. Generally, higher relative increases of nutrients in soil solution were surprisingly found in soil with higher pH and higher cation exchange capacity (CEC). Factors influencing dynamics of ash‐contained nutrients in soil solution are discussed. Nutrient leaching from straw and wood ash matrix in soil‐plant conditions is investigated. The influence of ashes on yield and nutrient uptake differed substantially depending on types of ash and soil. Highly soluble K‐compounds in straw ash revealed by X‐ray powder diffraction. Straw ash is a much more efficient P source than wood ash.

Perspectives for diagnostic and treatment in alcoholic encephalopathy at early disease stage

101 patients with alcoholic encephalopathy, aged from 30 to 60 years, were enrolled in the study. Patients were divided into three groups: 34 patients in the treatment group received neiromidin in a dose of 15 mg in solution during 10 days and then in tabs in a dose of 20 mg three times a day during 2 months; 32 patients in the treatment group received vasoactive, antioxidant treatment and metadoxil in a dose of 500 mg three times a day during 2 months. The comparison group included 35 patients receiving only vasoactive and antioxidant treatment. To the end of treatment, the positive changes in the state of patients reflected in the decrease in the number of complaints and neurological symptoms were seen in the treatment groups.

Evolution of calcite growth morphology in the presence of magnesium: Implications for the dolomite problem

The effect of magnesium on calcite growth morphology was known to occur as step rounding in some cases and surface segmentation in others. What remains unknown are the conditions for and the relations between the different effects, suggesting a lack of comprehensive understanding of the fundamental cause. Here we investigated the evolution of spiral hillock morphology on calcite cleavage surfaces in solutions with increasing Ca to Mg ratios and supersaturation levels using in situ atomic force microscopy. We isolated the effects of Mg and saturation by conducting experiments under conditions of constant pH, ionic strength, and Ca2+/CO32−. Our results revealed three types of morphological variations, ranging from step rounding in one direction (type I), to all directions (type II), and finally to a mosaic-like surface segmentation associated with monolayer buckling and step bunching (type III). These results suggest that the effect of magnesium on calcite growth depends upon multiple parameters including the concentration of Mg in solution, the step speed, as well as the extensiveness of Mg for Ca substitution in calcite lattice. We propose that the morphological variation may be understood by a model taken into consideration of (1) the lifespan and flux size of Mg ions at kinks in comparison to step kinetics, and (2) the diffusion and alignment of point defects created by the substitution of Mg for Ca in the crystal lattice. Stress calculations show that the maximum amount of Mg which calcite lattice can sustain before plastic deformation is ∼40%, suggesting that lattice stress due to the mismatch between MgCO3 and CaCO3 is likely the ultimate cause for the difficulty of ambient condition dolomite crystallization.

Efficient Loading of cisplatin into Superabsorbent Polymer Microsphere in the treatment of hepatocellular carcinoma.

Background: Although Superabsorbent Polymer (SAP) microsphere has been useful in treatment of multiple and large hepatocellular carcinoma, efficient loading procedure of cisplatin onto SAP was not established. Loading efficiency of cisplatin was evaluated from the viewpoint of passive concentration gradient and ionic strength. Methods: To load cisplatin into SAP particle, 50mg of cisplatin powder was dissolved in three manners of aqueous solutions: (a) 50mg of cisplatin powder plus 35ml of warmed physiological saline solution (0.9%), (b) 5ml of physiological saline solution (0.9%) plus a half of solution (5ml) of the product made from 50mg of cisplatin powder in 10ml of iohexol 350mgI/ml, and (c) 10ml of iohexol 350mgI/ml plus 0.25ml of 10% NaCl solution Results: Cisplatin dissolved sufficiently in all the three methods. Average amounts of loaded cisplatin into SAP particles were 1.7mg in solution (a), 6.6mg in solution (b), and 11.8mg in solution (c). Since alteration of ionic strength in the method (c) significantly affect the extent of SAP swelling, addition of 0.25ml of 10% NaCl was unquestionably necessary. Release of cisplatin from SAP was evidently gradual, showing 83.1% after 6 hours in static elution experiment and 68.6% after 1 hour in dynamic elution experiment. Conclusions: Cisplatin-loaded SAP may act as a drug delivery system for treatment of liver cancer, and loading of cisplatin should be consciously performed considering cisplatin concentration and ionic strength. (225words)

Effects of somatostatin against oxidative stress in mouse model of acute lung injury

Objective To investigate the effects and potential mechanisms of somatostatin (SST)against oxidative stress in a mouse model of lipopolysaccharide (LPS)-induced acute lung injury (ALI).Methods A total of 96 ICR male mice of specific pathogen free (SPF) were divided randomly (random number) into four groups:normal control group (n =24),SST control group (n =24),ALI group (n =24) and SST treated group (n =24).The mice of ALI group were given the intra-peritoneal injection of LPS in dose of 12 mg in solution of 40 mL/kg.Mice of normal control group were given the intra-peritoneal injection of equivalent volume of normal saline (NS 40 mL/kg) instead,and mice of SST control group were given the intra-peritoneal injection of equivalent volume of normal saline (40 mL/kg) instead,then hypodermic injection of SST (20 μg:20 mL/kg) at 0.5,2,6 or 12 h after normal saline administration,and mice of SST treated group were given the intra-peritoneal injection of LPS (12 mg:40 mL/kg),then hypodermic injection of SST (20 μg:20 mL/kg) at 0.5,2,6 or 12 h after LPS administration.All mice were sacrificed at 3,8 h or 16 h after the first injection of LPS or NS.The lung wet/dry ratios were calculated.Pathological changes of lung tissues were observed under light microscope after HE staining.The levels of malondialdehyde (MDA),superoxide dismutase (SOD) and catalase (CAT) in the lung tissues were determined by chemical colorimetry; quinone oxidoreductase (NQO-1) levels in the lung tissues were measured by ELISA ; the expressions of nuclear factor-E2-related factor2 (Nrf2) and its protein levels in the lung tissues were measured by RT-PCR and Western blotting,respectively.One-way analysis of variance (ANOVA) was employed for statistical analysis by using SPSS version 19.0 to compare values among all groups.Results There were no significant differences in all biomarker variables between normal control group and SST control group (P ＜ 0.05).Lung wet/dry ratios in ALI group at 8 h and 16 h were significantly higher than those in normal control group (P =0.000) and obviously lower in SST treated group (5.21 ±0.13) vs.(5.78±0.20),(5.39±0.29) vs.(6.17 ±0.17) (P=0.000).Compared with normal control group,the damage of lung tissues in ALI group was more severe.In contrast,histopathological lesions observed in SST treated group were milder significantly.The MDA and NQO-1 in the lung tissues were much higher in ALI group than those in normal control group,while the activities of SOD and CAT were much lower in ALI group (P =0.000).Compared with ALI group,the MDA level (ng/mg) in SST treated group decreased remarkably (2.66 ±0.18) vs.(3.58 ±0.26),(3.52 ±0.31)vs.(4.37 ±0.19),(3.81 ±0.38) vs.(4.92 ±0.25) (P=0.000),whereas CAT activity (U/mg)increased significantly (9.21± 0.47) vs.(7.90±0.32),(10.06±0.51) vs.(8.39±0.41),(10.98 ± 0.33) vs.(9.52 ± 0.55) (P =0.000) ; SOD activity and NQO-1 level at 3 h had no obvious increase (P =0.359、0.111),but SOD activities and NQO-1 levels were markedly increased at 8 h and 16 h [SOD (U/mg):(75.34±5.5) vs.(67.89±3.8),P=0.021; (64.82±4.2) vs.(50.31 ±5.0),P=0.000],[NQO-1 (ng/mg):(1.052 ±0.041) vs.(0.715±0.038),(1.338±0.027)vs.(0.532 ± 0.028),P =0.000].Compared with normal control group,the Nrf2 mRNA and protein levels in ALI group were higher markedly (P =0.000),and Nrf2 mRNA in SST treated group were much higher (P =0.023-0.000),while Nrf2 protein level at 3 h showed no significant difference (P =0.101)but increased obviously at 8 h,16 h (P =0.000).Conclusions Our study has shown that SST can upregulate Nrf2 signal pathway,which may have the effects on regulating the immune response and protections against oxidative damages in ALI. Key words: Lipopolysaccharide ; Acute lung injury; Somatostatin ; Oxidative Stress ; Nuclear factor-E2-related factor 2 ; Mice

Dolomite effect on borosilicate glass alteration

Dolomite (CaMg(CO3)2) is one of the common rock-forming minerals in many geological media, in particular in clayey layers that are currently considered as potential host formations for a deep radioactive waste disposal facility. Magnesium in solution is one of the elements known to potentially enhance the alteration of nuclear glasses. The alteration of borosilicate glasses with dolomite as a Mg-bearing mineral source was investigated for 8months in batch tests at 90°C. Glass composition effects were investigated through two compositions (SiBNaAlCaZrO and SiBNaAlZrO) differing in their Ca content. The Ca-rich glass alteration is slightly enhanced in the presence of dolomite compared to the alteration observed in pure water. This greater alteration is explained by the precipitation of Mg silicate phases on the dolomite and glass surfaces. In contrast, the Ca-free glass alteration decreases in the presence of dolomite compared to the alteration observed in pure water. This behavior is explained by Ca incorporation in the amorphous layer (formed during glass alteration) coming from dolomite dissolution. Calcium acts as a layer reorganizer and limits glass alteration by reducing the diffusion of reactive species through the altered layer. Modeling was performed using the GRAAL model implemented within the CHESS/HYTEC geochemical code to discriminate and interpret the mechanisms involved in glass/dolomite interactions. Magnesium released by dolomite dissolution reacts with silica provided by glass alteration to form Mg silicates. This reaction leads to a pH decrease. The main mechanism controlling glass alteration is the ability of dolomite to dissolve. During the experiment the quantities of secondary phases formed were very small, but for longer time scales, this mechanism could supply sufficient Mg in solution to form large amounts of Mg silicates and sustain glass alteration. The ability of the GRAAL model to reproduce the concentrations of elements in solution and solid phases regardless of the amount of dolomite and the glass composition strongly supports the basic modeling hypothesis.

Calcium and magnesium enhance arsenate rhizotoxicity and uptake in Triticum aestivum

Cations such as calcium (Ca) and magnesium (Mg) alleviate toxicities of cationic toxicants and increase those of anionic toxicants such as arsenic (As) present as arsenate under aerobic conditions. Increasing evidence exists that these phenomena are related to the outer surface electrical potential (ψ 0°) of the root cell plasma membrane (PM). Short-term (48-h) nutrient culture experiments with wheat (Triticum aestivum L.) seedlings investigated Ca and Mg effects on arsenate rhizotoxicity and uptake. Increased Ca and Mg in solution from 0.2 to 3.5 mM equally reduced the negativity of ψ 0° from -45 to -15 mV. This increased arsenate activity at the PM surface from 0.3 to 0.9 µM at the same bulk concentration of 2.0 µM NaH(2) AsO(4) consequently increased arsenate uptake and rhizotoxicity. However, increased Mg was more effective than Ca in enhancing As uptake by roots, especially with the activity of As in the range of 0.5 to 1.5 µM in the bulk medium. This was explained by a modified electrostatic uptake model which indicated a mechanism other than through an effect on ψ 0°. Subcellular fractionation of roots indicated that > 95% of As was associated with cellular debris and heat-stable protein (HSP). The results of the present study show that Ca and Mg reduce the negativity of ψ 0°, increasing arsenate uptake and rhizotoxicity, and suggest that Mg is more efficient than Ca in enhancing the uptake of As due, in large part, to inducing greater As binding by peptides in the HSP fraction.

Method development for the determination of cadmium in fertilizer samples using high-resolution continuum source graphite furnace atomic absorption spectrometry and slurry sampling

The determination of cadmium (Cd) in fertilizers is of major interest, as this element can cause growth problems in plants, and also affect animals and humans. High-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS) with charge-coupled device (CCD) array detection overcomes several of the limitations encountered with conventional line source AAS, especially the problem of accurate background measurement and correction. In this work an analytical method has been developed to determine Cd in fertilizer samples by HR-CS GF AAS using slurry sampling. Both a mixture of 10 μg Pd + 6 μg Mg in solution and 400 μg of iridium as permanent modifier have been investigated and aqueous standards were used for calibration. Pyrolysis and atomization temperatures were 600 °C and 1600 °C for the Pd-Mg modifier, and 500 °C and 1600 °C for Ir, respectively. The results obtained for Cd in the certified reference material NIST SRM 695 (Trace Elements in Multi-Nutrient Fertilizer) of 16.7 ± 1.3 μg g −1 and 16.4 ± 0.75 μg g −1 for the Pd–Mg and Ir modifier, respectively, were statistically not different from the certified value of 16.9 ± 0.2 μg g −1 on a 95% confidence level; however, the results obtained with the Ir modifier were significantly lower than those for the Pd–Mg modifier for most of the samples. The characteristic mass was 1.0 pg for the Pd–Mg modifier and 1.1 pg Cd for the Ir modifier, and the correlation coefficients (R 2) of the calibration were > 0.99. The instrumental limits of detection were 7.5 and 7.9 ng g −1, and the limits of quantification were 25 and 27 ng g −1 for Pd–Mg and Ir, respectively, based on a sample mass of 5 mg. The cadmium concentration in the investigated samples was between 0.07 and 5.5 μg g −1 Cd, and hence below the maximum value of 20 μg g −1 Cd permitted by Brazilian legislation.

A sol–gel method for growing superconductingMgB2 films

In this paper we report a new sol–gel method for the fabrication ofMgB2 films.Polycrystalline MgB2 films were prepared by spin-coating a precursor solution ofMg(BH4)2 diethylether on (001)Al2O3 substrates followed with annealing in Mg vapor. In comparison with theMgB2 films grownby other techniques, our films show medium qualities including a superconducting transition temperature ofTC ∼ 37 K, a critical currentdensity of JC(5 K, 0 T) ∼ 5 × 106 A cm − 2, anda critical field of HC2(0) ∼ 19 T. Such a sol–gel technique shows potential in the commercial fabrication of practically usedMgB2 films aswell as MgB2 wires and tapes.

Glucocorticoids reduce nitric oxide concentration in middle ear effusion from lipopolysaccharide induced otitis media

Objective Otitis media with effusion (OME) is a common childhood disease that is characterized by an accumulation of fluid in the middle ear. Chronic OME can also lead to sensorineural hearing loss (SNHL). Nitric oxide (NO), an inflammatory mediator (IM) of OME, is a free radical known to regulate cell proliferation, cell death, and angiogenesis. Previous studies have shown that nitric oxide may cause SNHL through outer hair cell (OHC) cytotoxicity. This experiment was designed to determine whether glucocorticoids, dexamethasone, fluticasone propionate, or rimexolone, can reduce the concentration of NO in middle ear effusion (MEE). Methods Fifty-three chinchillas were divided into 7 groups, vehicle vs. each glucocorticoid at 0.1% and 1.0% concentrations. Due to anesthesia complications, N ranged from 6 to 9 per group. Two hundred microlitres of each test article was injected into the bullae of each animal. Two hours later, lipopolysaccharide (LPS) (0.3 mg in solution) was added. Test articles were re-administered at 24 and 48 h post-LPS induction. After 96 h, animals were euthanized and the MEE was collected. Results All three glucocorticoids numerically reduced NO concentration in the middle ear when administered at 0.1%, but only FP showed a significant reduction. At 1.0% concentrations, all 3 steroids significantly reduced NO concentration. Conclusion This study suggests that glucocorticoid treatment reduces NO concentration in the MEE and may protect the ear from the SNHL caused by NO.

Three-Dimensional Micro-Actuator Fabrication by Aluminum Anodizing, Laser Irradiation, and Electrodepopsition

Three-dimensional micro-actuators, consisting of three-layer structure of acrylic acid resin / Au / polypyrrole, were fabricated by aluminum anodizing, laser irradiation, and electrochemical techniques. Anodized aluminum tube specimens were irradiated with a pulsed Nd-YAG laser to remove anodic oxide films, and then an Au layer was deposited at the area where film had been removed. The subsequent electrophoretic deposition of acrylic acid resin on the Au layer, dissolution of anodic oxide film and the metal substrate, and deposition of polypyrrole on backside of Au layer by electro-polymerization enabled the fabrication of a three-layer actuator. Cyclic voltammetry of the actuator showed that redox reactions of polypyrrole are accompanied with doping and dedoping of hydrated cations. The three-dimensional micro-actuator showed good performance as a manipulator, gripping and moving objects of several mg in solutions.

Adsorption of arsenite and arsenate onto muscovite and biotite mica

Arsenite and arsenate sorption was studied on two silt-sized phyllosilicates, namely muscovite and biotite, as a function of solution pH (pH 3–8 for muscovite, and 3–11 for biotite) at an initial As concentration of 13 μM. The amount of arsenic adsorbed increases with increasing pH, exhibiting a maximum value, before decreasing at higher pH values. Maxima correspond to 3.22 ± 0.06 mmol kg −1 As(V) at pH 4.6–5.6 and 2.86 ± 0.05 mmol kg −1 As(III) at pH 4.1–6.2 for biotite, and 3.08 ± 0.06 mmol kg −1 As(III) and 3.13 ± 0.05 mmol kg −1 As(V) at pH 4.2–5.5 for muscovite. The constant capacitance surface complexation model was used to explain the adsorption behavior. Biotite provides greater reactivity than muscovite toward arsenic adsorption. Isotherm data obeyed the Freundlich or Langmuir equation for the arsenic concentration range 10 −7–10 −4 M. Released total Fe, Si, K, Al, and Mg in solution were analyzed. Calculation of saturation indices by PHREEQC indicated that the solution was undersaturated with respect to aluminum arsenate (AlAsO 4⋅2H 2O), scorodite (FeAsO 4⋅2H 2O), and claudetite/arsenolite (As 4O 6).