Study on the Adsorption of Cr3+ by Peanut Shell: Adsorption Kinetics, Thermodynamics, and Isotherm Properties.

The pollution of heavy metals in soil to the environment is becoming more and more serious, resulting in the reduction of crop production and the occurrence of medical accidents. In order to remove heavy metal ions from soil and reduce the harm of heavy metals to the environment, modified peanut shell was used to adsorb Cr3+ in this article. The effects of different adsorption conditions on the adsorption rate and adsorption capacity of Cr3+ on ZnCl2 modified peanut shell were studied, the best adsorption conditions were explored, and the relationship of kinetics, thermodynamics and adsorption isotherm properties of adsorption process were explored. The results showed that the optimum adsorption pH value, dosage, initial concentration, adsorption temperature and contact time of ZnCl2 modified peanut shell were 2.5, 2.5 g/L, 75 µg/mL, 25 °C and 40 min, respectively. The prepared materials were characterized and analyzed by scanning electron microscope (SEM) and X-ray diffraction (XRD) analyzer. It was concluded that the modified peanut shell had a good adsorption capacity to Cr3+ . The kinetic study showed that the adsorption process of Cr3+ on peanut shell modified by zinc chloride was in accordance with the quasi-second-order kinetic model. The adsorption process belonged to exothermic reaction and belonged to spontaneous reaction process. In summary, it is proved that zinc chloride modified peanut shell can efficiently adsorb Cr3+ , which can be used for the treatment of heavy metal wastes in industry, which is beneficial to environmental protection and avoid heavy metal pollution.

New insights into two yeast BDHs from the PDH subfamily as aldehyde reductases in context of detoxification of lignocellulosic aldehyde inhibitors.

At least 24 aldehyde reductases from Saccharomyces cerevisiae have been characterized and most function in in situ detoxification of lignocellulosic aldehyde inhibitors, but none is classified into the polyol dehydrogenase (PDH) subfamily of the medium-chain dehydrogenase/reductase (MDR) superfamily. This study confirmed that two (2R,3R)-2,3-butanediol dehydrogenases (BDHs) from industrial (denoted Y)/laboratory (denoted B) strains of S. cerevisiae, Bdh1p(Y)/Bdh1p(B) and Bdh2p(Y)/Bdh2p(B), were members of the PDH subfamily with an NAD(P)H binding domain and a catalytic zinc binding domain, and exhibited reductive activities towards lignocellulosic aldehyde inhibitors, such as acetaldehyde, glycolaldehyde, and furfural. Especially, the highest enzyme activity towards acetaldehyde by Bdh2p(Y) was 117.95 U/mg with cofactor nicotinamide adenine dinucleotide reduced (NADH). Based on the comparative kinetic property analysis, Bdh2p(Y)/Bdh2p(B) possessed higher specific activity, substrate affinity, and catalytic efficiency towards glycolaldehyde than Bdh1p(Y)/Bdh1p(B). This was speculated to be related to their 49% sequence differences and five nonsynonymous substitutions (Ser41Thr, Glu173Gln, Ile270Leu, Ile316Met, and Gly317Cys) occurred in their conserved NAD(P)H binding domains. Compared with BDHs from a laboratory strain, Bdh1p(Y) and Bdh2p(Y) from an industrial strain displayed five nonsynonymous mutations (Thr12, Asn61, Glu168, Val222, and Ala235) and three nonsynonymous mutations (Ala34, Ile96, and Ala369), respectively. From a first analysis with selected aldehydes, their reductase activities were different from BDHs of laboratory strain, and their catalytic efficiency was higher towards glycolaldehyde and lower towards acetaldehyde. Comparative investigation of kinetic properties of BDHs from S. cerevisiae as aldehyde reductases provides a guideline for their practical applications in in situ detoxification of aldehyde inhibitors during lignocellulose bioconversion.Key Points• Two yeast BDHs have enzyme activities for reduction of aldehydes.• Overexpression of BDHs slightly improves yeast tolerance to acetaldehyde and glycolaldehyde.• Bdh1p and Bdh2p differ in enzyme kinetic properties.• BDHs from strains with different genetic backgrounds differ in enzyme kinetic properties.

Nitrogen Regulating the Expression and Localization of Four Glutamine Synthetase Isoforms in Wheat (Triticum aestivum L.).

Glutamine synthetase (GS), the key enzyme in plant nitrogen assimilation, is strictly regulated at multiple levels, but the most relevant reports focus on the mRNA level. Using specific antibodies as probes, the effects of nitrogen on the expression and localization of individual wheat GS (TaGS) isoforms were studied. In addition to TaGS2, TaGS1;1 with high affinity to substrate and TaGS1;3 with high catalytic activity were also localized in mesophyll, and may participate in cytoplasmic assimilation of ammonium (NH4+) released from photorespiration or absorbed by roots; TaGS1;2 was localized in xylem of leaves. In roots, although there were hundreds of times more TaGS1;1 than TaGS1;2 transcripts, the amount of TaGS1;1 subunit was not higher than that of TaGS1;2; NH4+ inhibited TaGS1;1 expression but stimulated TaGS1;3 expression. In root tips, nitrate stimulated TaGS1;1, TaGS1;3, and TaGS2 expression in meristem, while NH4+ promoted tissue differentiation and TaGS1;2 expression in endodermis and vascular tissue. Only TaGS1;2 was located in vascular tissue of leaves and roots, and was activated by glutamine, suggesting a role in nitrogen transport. TaGS1;3 was induced by NH4+ in root endodermis and mesophyll, suggesting a function in relieving NH4+ toxicity. Thus, TaGS isoforms play distinct roles in nitrogen assimilation for their different kinetic properties, tissue locations, and response to nitrogen regimes.

Glycosylation of ß1 subunit plays a pivotal role in the toxin sensitivity and activation of BK channels.

BACKGROUND: The accessory ß1 subunits, regulating the pharmacological and biophysical properties of BK channels, always undergo post-translational modifications, especially glycosylation. To date, it remains elusive whether the glycosylation contributes to the regulation of BK channels by ß1 subunits. METHODS: Herein, we combined the electrophysiological approach with molecular mutations and biochemical manipulation to investigate the function roles of N-glycosylation in ß1 subunits. RESULTS: The results show that deglycosylation of ß1 subunits through double-site mutations (ß1 N80A/N142A or ß1 N80Q/N142Q) could significantly increase the inhibitory potency of iberiotoxin, a specific BK channel blocker. The deglycosylated channels also have a different sensitivity to martentoxin, another BK channel modulator with some remarkable effects as reported before. On the contrary to enhancing effects of martentoxin on glycosylated BK channels under the presence of cytoplasmic Ca2+, deglycosylated channels were not affected by the toxin. However, the deglycosylated channels were surprisingly inhibited by martentoxin under the absence of cytoplasmic Ca2+, while the glycosylated channels were not inhibited under this same condition. In addition, wild type BK (α+ß1) channels treated with PNGase F also showed the same trend of pharmacological results to the mutants. Similar to this modulation of glycosylation on BK channel pharmacology, the deglycosylated forms of the channels were activated at a faster speed than the glycosylated ones. However, the V1/2 and slope were not changed by the glycosylation. CONCLUSION: The present study reveals that glycosylation is an indispensable determinant of the modulation of ß1-subunit on BK channel pharmacology and its activation. The loss of glycosylation of ß1 subunits could lead to the dysfunction of BK channel, resulting in a pathological state.

Thermoluminescence of single wall carbon nanotubes synthesized by hydrogen-arc-discharge method.

Single Wall Carbon Nanotubes (SWNT) synthesized by the hydrogen-arc-discharge method were tested as thermoluminescent (TL) material and found to be highly resistant to gamma radiation. Gamma irradiation of the as-prepared material with doses between 1 and 20 kGy induced changes on the morphology of the SWNT, such as nanoloops, as observed by Scanning Electron Microscopy. From X-ray diffraction, the as-prepared material shows content of various forms of carbon, including nanotubes, hexagonal carbon (graphite), and rhombohedral carbon too. The full width at half maximum (FWHM) of diffraction peaks remain practically unchanged after irradiation. The glow curves show a single TL peak centered at about 449 K. Because the complex structure of the glow curves, it seems that the TL signal could be produced by a trap distribution instead of a single level of traps. To dilucidate the mechanism responsible of glow curves and the value of activation energy of traps, kinetic parameters like Eeff, ΔE, and s of experimental the glow curves have been analyzed using computerized glow curve deconvolution (CGCD) considering a continuous distribution of trapping levels, peak shape and initial rise methods, as well as heuristic equations. The measured TL dosimetric properties may be summarized as follows: (a) moderate reproducibility of the TL signal (coefficient of variation 24.87%); (b) main peak activation energy of 1.206 eV; (c) threshold dose of ~1 kGy; (d) TL-sensitivity of ~7.0 × 10-4; (e) human bone equivalence, i.e., high-Z material, Zeff = 15 and, (f) wide linear range of TL dose-response in the range 0.170-2.5 kGy.

Exfoliated graphite with graphene flakes as potential candidates for TL dosimeters at high gamma doses.

Graphite powder (GP) subjected to microwave radiation (MWG) results in exfoliation of graphite particles into few-layered graphene flakes (GF) intermixed with partially exfoliated graphite particles (PEG). Characterization of MWG by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and Raman spectroscopy reveal few-layer GF with sizes ranging from 0.2 to 5 µm. Raman D, G, and 2D (G') bands characteristic of graphitic structures include evidence of the presence of bilayered graphene. The thermoluminescent (TL) dosimetric properties of MWG are evaluated and can be characterized as a gamma-ray sensitive and dose-resistant material with kinetic parameters (activation energy for the main peak located at 400 and 408 K is 0.69 and 0.72 eV) and threshold dose (~1 kGy and 5 kGy respectively). MWG is a low-Z material (Zeff = 6) with a wide linear range of TL dose-response (0.170-2.5 kGy) tested at doses in the 1-20 kGy range with promising results for applications in gamma-ray dosimetry. Results obtained in gamma irradiated MWG are compared with those obtained in graphite powder samples (GP) without microwave treatment.

Glycosylation of ß1 subunit plays a pivotal role in the toxin sensitivity and activation of BK channels

The accessory ß1 subunits, regulating the pharmacological and biophysical properties of BK channels, always undergo post-translational modifications, especially glycosylation. To date, it remains elusive whether the glycosylation contributes to the regulation of BK channels by ß1 subunits. Methods: Herein, we combined the electrophysiological approach with molecular mutations and biochemical manipulation to investigate the function roles of N-glycosylation in ß1 subunits. Results: The results show that deglycosylation of ß1 subunits through double-site mutations (ß1 N80A/N142A or ß1 N80Q/N142Q) could significantly increase the inhibitory potency of iberiotoxin, a specific BK channel blocker. The deglycosylated channels also have a different sensitivity to martentoxin, another BK channel modulator with some remarkable effects as reported before. On the contrary to enhancing effects of martentoxin on glycosylated BK channels under the presence of cytoplasmic Ca2+, deglycosylated channels were not affected by the toxin. However, the deglycosylated channels were surprisingly inhibited by martentoxin under the absence of cytoplasmic Ca2+, while the glycosylated channels were not inhibited under this same condition. In addition, wild type BK (α+ß1) channels treated with PNGase F also showed the same trend of pharmacological results to the mutants. Similar to this modulation of glycosylation on BK channel pharmacology, the deglycosylated forms of the channels were activated at a faster speed than the glycosylated ones. However, the V1/2 and slope were not changed by the glycosylation. Conclusion: The present study reveals that glycosylation is an indispensable determinant of the modulation of ß1-subunit on BK channel pharmacology and its activation. The loss of glycosylation of ß1 subunits could lead to the dysfunction of BK channel, resulting in a pathological state.(AU)

Novel nanoemulsion based lipid nanosystems for favorable in vitro and in vivo characteristics of curcumin.

The goal of this study was to assess the enhanced elementary characteristics, in vitro release, anti-cancer cytotoxicity, in situ absorption and in vivo bioavailability of a novel nanoemulsion based lipid nanosystems containing curcumin (CNELNs) when administered orally. The CNELNs were first fabricated by loading water-in-oil nanoemulsions into lipid nanosystems using a nanoemulsion-film dispersion-sonication method. The gastro-intestinal absorption, in vitro release and in vivo kinetic property of CNELNs were investigated using an in situ perfusion method, a dialysis method and a concentration-time curve based method, respectively. The inhibitory effects of CNELNs on human lung cancer A549 cell growth were determined using MTT assay. The absorption constants and effective permeabilities of CNELNs in different gastro-intestinal tracts increased 2.29-4.04 times and 4.06-8.27 times that of curcumin (CUR), respectively. The relative bioavailability of CNELNs to free CUR was 733.59%. CNELNs inhibited A549 growth in a dose- and time-dependent manner. CNELNs markedly improved the oral bioavailability of CUR which was probably due to the increased gastro-intestinal absorption. CNELNs had stronger inhibitory effects on the viabilities of A549 cells than that of free CUR. CNELNs might be promising nanosystems for oral delivery of CUR to satisfy clinical requirements.

Thermoluminescence and photoluminescence analyses of MEH-PPV, MDMO-PPV and RU(bpy)3 gamma-irradiated polymer thin films.

Effects of irradiation with (60)Co gamma photons on poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), poly[2-methoxy-5-(3',7' dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) and tris(2,2'-bipyridyl)dichlororuthenium(II) hexahydrate (Ru(bpy)3) thin films were analyzed regarding their thermoluminescence (TL) and photoluminescence (PL) properties. A linear TL dose response was obtained from the MEH-PPV and MDMO-PPV polymer films in dose ranges of approximately 0.170-4.08kGy and 0.170-0.850kGy, respectively, followed by a supralinear behavior. A dependence on the conjugation length of the polymer chains which was favored by heating of the film, was observed, and irradiation generated a blue-shift in MEH-PPV and Ru(bpy)3. Furthermore, the PL structure was not modified. The most likely effect involved in the TL emission was trapping. The high activation energy values of the traps in the TL may be attributed in part to the binding energy of the exciton. A deconvolution process was carried out to obtain the kinetic parameters from the TL glow curves and PL spectra.