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1.
Biochim Biophys Acta Proteins Proteom ; 1868(8): 140439, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32371148

RESUMO

The present article reviews the results of solid-state vibrational circular dichroism (SD-VCD) measurements on the crystals of amino acids. The investigated series were Ala, Ile, Leu, Phe, Ser, Val, and Thr. Spectra were recorded for the samples containing both D- and L-enantiomers. The molecular conformation in a crystalline state was compared among the series. Molecule optimization of their conformation under intermolecular interactions in crystalline states was revealed. One noteworthy aspect was that some VCD peaks were remarkably enhanced in comparison with the solution states. This fact was rationalized in terms of vibrationally coupled delocalization in a closely stacked pair. In addition, for a molecule with two asymmetric carbons, the signs of the VCD peaks were determined by the interplay between the two chiral centers. Lastly, the roles of the theoretical approach based on density functional theory calculations were described.


Assuntos
Aminoácidos/química , Dicroísmo Circular/métodos , Brometos/química , Cristalização , Conformação Molecular , Compostos de Potássio/química , Teoria Quântica , Estereoisomerismo , Vibração
2.
Poult Sci ; 99(3): 1717-1723, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32115039

RESUMO

The effect of high-pressure processing (200 MPa, 10 min) on the solubility of chicken breast myosin with 25% molar substitution of Na+ by 3 anion types of potassium salts (KCl, K-lactate, and K-citrate) was investigated. The results showed that the lower hydrophobic group and reactive sulfhydryl group of nonpressurized myosin with the replacement of organic K-lactate or K-citrate possibly contributed to the aggregation of myosin molecules compared with the KCl group and thus decreased the solubility of both. In the presence of lactate or citrate, the high-pressure processing caused an increase in the surface hydrophobicity and reactive sulfhydryl group, indicating the unfolding of myosin molecule. Meanwhile, the increased hydration state and the decreased apparent viscosity suggested the disruption of protein-protein interactions and the strengthening of myosin-water interactions in pressurized myosin, ultimately resulting in increased solubility of the pressurized myosin with both organic potassium salts. The compensation of high-pressure processing is interesting for the efficient selection of the anion type in developing sodium-reduced industrial meat products.


Assuntos
Galinhas , Manipulação de Alimentos/métodos , Miosinas/química , Compostos de Potássio/química , Animais , Produtos Avícolas , Pressão , Solubilidade
3.
Nat Commun ; 11(1): 1449, 2020 03 19.
Artigo em Inglês | MEDLINE | ID: mdl-32193375

RESUMO

Pollen's practically-indestructible shell structure has long inspired the biomimetic design of organic materials. However, there is limited understanding of how the mechanical, chemical, and adhesion properties of pollen are biologically controlled and whether strategies can be devised to manipulate pollen beyond natural performance limits. Here, we report a facile approach to transform pollen grains into soft microgel by remodeling pollen shells. Marked alterations to the pollen substructures led to environmental stimuli responsiveness, which reveal how the interplay of substructure-specific material properties dictates microgel swelling behavior. Our investigation of pollen grains from across the plant kingdom further showed that microgel formation occurs with tested pollen species from eudicot plants. Collectively, our experimental and computational results offer fundamental insights into how tuning pollen structure can cause dramatic alterations to material properties, and inspire future investigation into understanding how the material science of pollen might influence plant reproductive success.


Assuntos
Ciência dos Materiais , Microgéis/química , Pólen/química , Biomimética/métodos , Química Computacional , Epitopos/química , Epitopos/imunologia , Esterificação , Dureza , Hidrólise , Hidróxidos/química , Microscopia de Fluorescência , Pectinas/química , Pectinas/imunologia , Pólen/imunologia , Polinização/fisiologia , Compostos de Potássio/química , Espectroscopia de Infravermelho com Transformada de Fourier
4.
Carbohydr Polym ; 235: 115952, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32122487

RESUMO

Chitin is the second most abundant and renewable polysaccharide, next to cellulose. Hydrolysis of abundant and highly crystalline α-chitin, pretreated with KOH and KOH-urea aqueous solutions, by a single modular endo-chitinase from Enterobacter cloacae subsp. cloacae (EcChi1) was investigated. The hydrolysis of untreated α-chitin and colloidal chitin by EcChi1 produced N-acetylglucosamine and N, N'-diacetylchitobiose, whereas, hydrolysis of treated substrates generated N, N', N''-triacetylchitotriose, in addition to N-acetylglucosamine and N, N'-diacetylchitobiose. The total amount of chitooligosaccharides (COS) generated by EcChi1 from pretreated substrates was 10 to 25-fold higher compared to untreated α-chitin at 24 h (depending on the solvent type and state of substrate). EcChi1 released higher amount of DP1 and DP2 products on treated α-chitin, with a fold change of 45 and 18, respectively. Treatment of α-chitin with KOH/KOH-urea is, therefore, a promising approach for an efficient conversion of rich source of chitin to soluble COS by chitinases like EcChi1.


Assuntos
Quitina/química , Quitinases/química , Enterobacter cloacae/enzimologia , Hidróxidos/química , Compostos de Potássio/química , Ureia/química , Quitina/metabolismo , Quitinases/metabolismo , Hidrólise , Hidróxidos/metabolismo , Compostos de Potássio/metabolismo , Ureia/metabolismo
5.
Braz Oral Res ; 34: e018, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32187304

RESUMO

The objective of this study was to evaluate the influence of hydrofluoric acid (HF) concentration, etching time, and application of phosphoric acid (PA) followed by neutralization with sodium bicarbonate on the bond strength between a feldspar ceramic and resin cement. Thus, 80 blocks (10 x 12 x 2 mm) of glass ceramic (VM - Vita Mark II - Vita Zahnfabrik) were made and randomly assigned to eight groups (n = 10) according to the factors: HF concentration (5 and 10%), etching time (60 and 120 s), and use of phosphoric acid (PA) (with and without). According to the experimental group, 37% PA (Condac, FGM) was applied after HF etching for 60s. Afterwards, samples were immersed in sodium bicarbonate for 1 min then in an ultrasonic bath in distilled water (5 min) for cleaning. After surface bonding treatment, cylinders (Ø = 2 mm; h = 2 mm) of dual resin cement (AllCem / FGM) were made in the center of each block. The samples were then stored in water (37ºC) for 90 days and submitted to the shear bond test (50 KgF, 1 mm/min). Failure analysis was performed by stereomicroscope and scanning electron microscopy. Data (MPa) were analyzed with 3-way ANOVA and Tukey's test. Only the factor "HF concentration" was significant (p = 0.02). Most failures were of cohesive in ceramic (40%) and mixed types (42.5%). The 10% HF resulted in higher shear bond strength value than the 5% HF. Surface cleaning with phosphoric acid followed by sodium bicarbonate and HF time (60 or 120 seconds) did not influence the resin bond strength to feldspar ceramic.


Assuntos
Silicatos de Alumínio/química , Colagem Dentária/métodos , Ácido Fluorídrico/química , Ácidos Fosfóricos/química , Compostos de Potássio/química , Análise de Variância , Porcelana Dentária/química , Teste de Materiais , Metacrilatos/química , Microscopia Eletrônica de Varredura , Valores de Referência , Reprodutibilidade dos Testes , Cimentos de Resina/química , Resistência ao Cisalhamento/efeitos dos fármacos , Silanos/química , Propriedades de Superfície , Fatores de Tempo
6.
Chemosphere ; 248: 126094, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32041073

RESUMO

Microalgae have been considered as promising alternative for CO2 fixation and wastewater purification. In our previous work, a hybrid microalgae CO2 fixation concept has been put forward, which initially used carbonate solution absorb CO2, and then provided obtained bicarbonate as nutrition for microalgae growth to avoid the challenge of low CO2 solubility and carbon fixation efficiency in the conventional process. In this work, the proposed hybrid system was further intensified via integrating soybean wastewater nutrition removal with bicarbonate-carbon (NH4HCO3 and KHCO3) conversion. The investigation results indicated that the maximum biomass productivity (0.74 g L-1) and carbon bioconversion efficiency (46.9%) were achieved in low-NH4HCO3 concentration system with pH adjusted to 7. pH adjustment of different bicarbonate systems also enhanced total nitrogen (TN), total phosphorus (TP) and chemical oxygen demand (COD) removal efficiency up to 87.5%, 99.5% and 77.6%, respectively. In addition, maximum neutral lipid (14.4 mg L-1·d-1) and polysaccharide (14.5 mg L-1·d-1) productivities could be obtained in the KHCO3 systems, while higher crude protein productivity (48.1 mg L-1·d-1) was yielded in the NH4HCO3 systems.


Assuntos
Bicarbonatos/química , Ciclo do Carbono , Microalgas/metabolismo , Compostos de Potássio/química , Soja/metabolismo , Águas Residuárias/química , Purificação da Água/métodos , Análise da Demanda Biológica de Oxigênio , Biomassa , Carbono/metabolismo , Dióxido de Carbono/metabolismo , Concentração de Íons de Hidrogênio , Microalgas/crescimento & desenvolvimento , Nitrogênio/metabolismo , Fósforo/metabolismo , Reciclagem
7.
Org Biomol Chem ; 18(4): 666-670, 2020 01 28.
Artigo em Inglês | MEDLINE | ID: mdl-31894805

RESUMO

A metal-free K2S2O8-HFIP synergistically promoted double Friedel-Crafts alkylation between a glycine derivative and N-substituted aniline was developed to efficiently synthesize diarylmethane derivatives with high para-selectivity. The reaction proceeded smoothly in the absence of any metal and ligand, and exhibited a good tolerance of functional groups.


Assuntos
Ésteres/química , Glicina/análogos & derivados , Compostos de Potássio/química , Propanóis/química , Sulfatos/química , Alquilação , Compostos de Anilina/síntese química , Compostos Benzidrílicos/síntese química , Modelos Químicos , Estrutura Molecular , Oxirredução
8.
Chemosphere ; 243: 125331, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31995863

RESUMO

The effects of reaction temperature, residence time, sulfuric acid and potassium hydroxide on the total concentration and speciation of N and P, potentially toxic elements (salts and metal elements) of pig manure during its hydrothermal carbonization (HTC) were investigated. Concentrations of Cl, K, Na and Mg in the hydrochars were much lower but total N, P and nitrate-nitrogen (NO3--N) contents were significantly higher than in untreated pig manure. The acid-extractable fractions of Cu and Zn in hydrochars were 0.03-0.63 and 0.17-0.66 times lower than those in pig manure and decreased significantly with increasing reaction temperature. The addition of sulfuric acid (H2SO4) or potassium hydroxide (KOH) in HTC reduced the contents of P, Ca, Mg, Cl and heavy metal elements (HMEs) in hydrochars, and the removal rates of Cu and Zn were up to 55% and 59%, respectively. Overall, the rapid treatment of pig manure by HTC reduced the harm of salts and HMEs, and effectively recovered the nutrients in pig manure. The HTC under alkaline conditions was desirable for optimizing the main elemental composition of the hydrochars.


Assuntos
Esterco , Eliminação de Resíduos Líquidos/métodos , Animais , Carbono , Hidróxidos/química , Esterco/análise , Metais Pesados/análise , Minerais/análise , Nitrogênio/análise , Fósforo/química , Compostos de Potássio/química , Ácidos Sulfúricos/química , Suínos , Temperatura , Fatores de Tempo
9.
Artigo em Inglês | MEDLINE | ID: mdl-31903843

RESUMO

In order to treat selenium pollution, the study presents the use of potassium ferrate (K2FeO4) as an environmentally friendly agent for in situ removal of Se(IV) from aqueous media. Batch experiments were carried out to evaluate the influences of various factors including dosage of K2FeO4, ex-situ and in-situ adsorption, initial pH, and adsorption isotherms. The results showed that increasing dosage of K2FeO4 benefited the removal of total selenium with the efficiency up to 97.0% and Se(IV) removal significantly depended on pH, and as the pH increases, the decrease in Se(IV) adsorption efficiency is a general trend of pH dependence. The X-ray powder diffraction, Fourier transformed infrared spectrometer and high-resolution X-ray photoelectron spectroscopy analysis indicated that Se(IV) was removed from the aqueous solution by adsorbing on the surface of the decomposition products of K2FeO4 which are ferric oxide nanoparticles, and the selenium adsorbed on the generated ferric oxide nanoparticles existed in the forms of Se(IV) and Se(VI). Se(IV) and Se(VI) were adsorbed to the decomposition products of K2FeO4 by forming an inner-sphere complexes and an outer-sphere complexes, respectively.


Assuntos
Compostos Férricos/química , Compostos de Ferro/química , Nanopartículas/química , Compostos de Potássio/química , Selênio/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Adsorção , Concentração de Íons de Hidrogênio , Oxirredução , Espectroscopia Fotoeletrônica , Selênio/química , Poluentes Químicos da Água/química , Difração de Raios X
10.
J Pharm Biomed Anal ; 177: 112846, 2020 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-31522097

RESUMO

The ß-lactam core is a key structure responsible for inducing both IgE-mediated acute-onset hypersensitivity and T-cell-mediated delayed-onset hypersensitivity with penicillins in humans. There is essentially no clinically significant immunologic cross-reactivity noted between the ß-lactam cores of penicillins and cephalosporins based on challenge studies in humans. The side-chains appear to be more important in inducing IgE-mediated acute-onset hypersensitivity and T-cell delayed-onset hypersensitivity with cephalosporins in humans. Despite these clinical findings, the U. S. Food and Drug Administration (FDA) still requires the level of ß-lactam-related antibiotic residues to be controlled at very low levels in manufacturing facilities. Ceftolozane is Merck & Co., Inc., Kenilworth, NJ, USA's (MSD's) 5th generation broad spectrum cephalosporin antibiotic against gram-negative bacteria. In searching for the optimal decontamination method of ceftolozane, most methods were found to be very slow in opening the ß-lactam ring in ceftolozane. Moreover, most of the previously reported decontamination methods applied analytical methods that only monitored the disappearance of the parent molecule as the endpoint of degradation. In this way, many of the ß-lactam-containing degradation products could be overlooked. In order to develop an efficient decontamination solution for ceftolozane, a sensitive ultra high performance liquid chromatography-high resolution-electrospray ionization-tandem mass spectrometry (UHPLC-HRMS/MS) method was first developed to ensure the detection of the ß-lactam ring in all degradation products. Through online UHPLC-UV-HRMS monitoring, 2.5 N KOH in 50% aqueous MeOH or 50% aqueous EtOH was identified as the best condition to fully degrade the ß-lactam ring in ceftolozane. This decontamination could be done within 15 min, even at 100 mg/mL concentration, and thus enable a quick turnaround time for equipment cleaning in the ß-lactam manufacturing facility. This method was also successfully applied to 12 other commercially available ß-lactam antibiotics.


Assuntos
Antibacterianos/análise , Cefalosporinas/análise , Descontaminação/métodos , Composição de Medicamentos/instrumentação , Contaminação de Equipamentos/prevenção & controle , Antibacterianos/química , Antibacterianos/toxicidade , Cefalosporinas/química , Cefalosporinas/toxicidade , Cromatografia Líquida de Alta Pressão/métodos , Composição de Medicamentos/métodos , Composição de Medicamentos/normas , Etanol/química , Hidróxidos/química , Metanol/química , Compostos de Potássio/química , Solventes/química , Espectrometria de Massas por Ionização por Electrospray/métodos , Espectrometria de Massas em Tandem/métodos
11.
Food Chem ; 309: 125672, 2020 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-31671374

RESUMO

Shrimp waste containing a substantial amount of valuable nutrients presents a challenge for food industry. In this work, extraction of astaxanthin from shrimp waste via aqueous biphasic systems (ABS) composed of ionic liquids (ILs) and potassiumphosphate (K3PO4) was investigated. The influence of phosphonium- and ammonium-based ILs and temperature on the phase behavior and astaxanthin extraction was evaluated. The hydrogen-bond basicity of each IL studied shows a negative linear correlation with tie-line lengths of ABS and a positive linear correlation with extraction efficiency (EEAst). In general, lower temperature are favourable for astaxanthin extraction. Tributyloctylphosphonium bromide ([P4448]Br) resulted in the strongest ABS formation ability and bonding interactions between the anion and astaxanthin. Compared with organic solvents, [P4448]Br + K3PO4 ABS achieved higher EEAst of 93.08% at 308 K. The chemical properties provide the possibility of prescreening appropriate ILs for ABS formation and predicting the partition of a target molecule.


Assuntos
Líquidos Iônicos/química , Fosfatos/química , Compostos de Potássio/química , Água/química , Concentração de Íons de Hidrogênio , Solventes/química , Temperatura , Termodinâmica , Viscosidade , Xantofilas/análise , Xantofilas/isolamento & purificação
12.
Braz Oral Res ; 33: e095, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31618283

RESUMO

This study evaluates the shear bond strength (SBS) of various resin cements to different ceramics. Composite resin cylinders of Z100 were fabricated and cemented to disks of feldspathic ceramic (Creation), leucite-reinforced feldspathic ceramic (Empress I), and densely sintered aluminum oxide ceramic (Procera AllCeram) using five resin cements: Panavia F (PAN), RelyX ARC (ARC), RelyX Unicem (RXU), RelyX Veneer, and Variolink II. SBS was measured after three days of water storage (baseline) and after artificial aging (180 days of water storage along with 12,000 thermal cycles). Failure mode of fractured specimens also was evaluated. Data were analyzed with Kruskal-Wallis and Mann-Whitney tests (α=0.05). RXU showed 1) the lowest baseline median SBS to feldspathic ceramic, which was not statistically different from PAN; 2) the lowest median baseline SBS to leucite-reinforced feldspathic and densely sintered aluminum-oxide ceramics. All cements performed similarly after aging, except for ARC (median 0.0 MPa) and PAN (median 16.2 MPa) in the densely sintered aluminum-oxide ceramic group. Resin cements perform differently when bonded to different ceramic substrates. While all test resin cements worked similarly in the long-term to feldspathic and leucite-reinforced feldspathic ceramics, only the MDP-containing resin cement provided durable bonds to densely sintered aluminum-oxide ceramic.


Assuntos
Cerâmica/química , Colagem Dentária/métodos , Cimentos de Resina/química , Alumínio/química , Silicatos de Alumínio/química , Teste de Materiais , Compostos de Potássio/química , Valores de Referência , Reprodutibilidade dos Testes , Resistência ao Cisalhamento , Estatísticas não Paramétricas , Propriedades de Superfície
13.
Anal Chim Acta ; 1090: 57-63, 2019 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-31655646

RESUMO

Electrochemiluminescence resonance energy transfer (ECL-RET) between quantum dots (QDs) was firstly proposed. In this work, boron nitride quantum dots (BNQDs) as the donor and nitrogen doped graphene quantum dots (NGQDs) as the acceptor were confirmed by the absorption spectrum, the emission spectrum and fluorescence spectrum. Based on the reaction between FA and the SO4•- in the ECL system of NGQDs/BNQDs/K2S2O8, the ECL sensing platform for FA was successfully constructed. Surprisingly, a stable and strong ECL signal was obtained based on the RET, which was used for signal-off detection of FA in the presence of coreactant K2S2O8. Notably, about 10-fold enhancement was observed compared with the absence of BNQDs. The proposed sensor showed wide linear ranges of 1.0 × 10-11 M to 1.0 × 10-4 M and a low detection limit of 5.13 × 10-12 M. Simultaneously, the sensor was successfully applied to detection of FA in human serum samples with excellent recoveries. Therefore, the NGQDs/BNQDs system provided a new perspective for development of novel ECL-RET sensors.


Assuntos
Compostos de Boro/química , Ácido Fólico/sangue , Grafite/química , Compostos de Potássio/química , Pontos Quânticos/química , Sulfatos/química , Técnicas Eletroquímicas/métodos , Transferência de Energia , Humanos , Limite de Detecção , Medições Luminescentes/métodos , Nitrogênio/química , Reprodutibilidade dos Testes
14.
Carbohydr Polym ; 224: 115176, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31472871

RESUMO

Weak mechanical properties, lack biocompatibility and relatively bioinert are formidable obstruct in application of bone repair materials. Multifunctional composite materials have been considered as a viable solution to this problem. Here, a new double network (DN) hydrogel was constructed by physical cross-linking of medical grade poly (vinyl alcohol) (PVA) and chitosan in KOH/urea dissolution system. The obtained hydrogel demonstrated excellent tensile strength (0.24 MPa), elongation at break (286%), and high compressive strength (0.11 MPa on the strain of 60%). Our studies showed that the prepared hydrogel had excellent biocompatibility in vitro and the introduction of hydroxyapatite (HAp) by surface mineralization imparted hydrogel the ability to induce rat bone marrow stem cells (rBMSCs) differentiation. The in vivo experiments revealed that the surface mineralized double network hydrogel significantly accelerated simultaneous regeneration of bone defects in a rabbit bone defect model. All the results indicated that this hydrogel has the potential as a bone repair material.


Assuntos
Osso e Ossos/efeitos dos fármacos , Quitosana/química , Hidrogéis/química , Hidrogéis/farmacologia , Minerais/química , Álcool de Polivinil/química , Adsorção , Animais , Osso e Ossos/citologia , Osso e Ossos/fisiologia , Adesão Celular/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Força Compressiva , Hidróxidos/química , Osteogênese/efeitos dos fármacos , Compostos de Potássio/química , Coelhos , Soroalbumina Bovina/química , Propriedades de Superfície , Resistência à Tração , Engenharia Tecidual , Ureia/química
15.
Sci Total Environ ; 692: 844-853, 2019 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-31539990

RESUMO

High-quality meso/micropore-controlled hierarchical porous carbon (HPC) was synthesized by a hard template method utilizing rice husk biochar and then used to adsorb copper ions from an aqueous solution. The preparation procedure included two main steps: base leaching and physicochemical activation. During the activation process, the porosity characteristics (i.e., specific surface area and meso/micropore ratio) were controlled by altering the KOH impregnation ratio, activation time, and temperature under the CO2 atmosphere. In addition, a copper adsorption study was performed using three HPC samples with different pore structures and characteristics. The results of this study indicate that the adsorption capacity of HPC material derived from rice husk biochar is strongly influenced by its meso/micropore ratio. As evidenced, HPC 3-0.5-800, which was impregnated by a KOH:biochar ratio of 3 and activated at 800°C for 0.5h under a CO2 atmosphere, has a very high specific surface area of 2330 m2g-1 with an 81% mesopore to total specific surface area. Importantly, it exhibited a superior adsorption capacity of 265mgg-1 and rapid adsorption kinetics for copper ions. The improvement is ascribed to the high specific surface area and favorable hierarchical structure. The findings demonstrate the feasibility of controlling the hierarchical pore structure of rice husk biochar-derived carbons as high-performance adsorbents for copper ion removal from water.


Assuntos
Carvão Vegetal/química , Cobre/análise , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Adsorção , Hidróxidos/química , Cinética , Oryza/química , Porosidade , Compostos de Potássio/química , Eliminação de Resíduos Líquidos/instrumentação , Purificação da Água/instrumentação
16.
Environ Pollut ; 255(Pt 1): 113179, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31542670

RESUMO

The immobilization effectiveness between Pb and phosphorus in soil varies with soil types. To clarify the effect of phosphate on the availability of Pb in agricultural soil, a culture experiment with three types of paddy soil was performed with potassium dihydrogen phosphate (KDP) added. EDTA, DGT and in-situ solution extraction methods were used to represent different available Pb content. Results showed that the concentration of EDTA-Pb in HN soil was slightly elevated after exogenous KDP added. The supplement of 300 mg/kg KDP significantly increased the content of soluble Pb in both acid silty clay loam soil and neutral silty loam soil (increased by 104.65% and 65.12%, respectively). However, there was no significant influence of KDP on the concentration of DGT extracted Pb. XANES results showed that Pb(OH)2, PbHPO4, humic acid-Pb and GSH-Pb were the major speciation of Pb in soil colloids. The proportion of Pb(OH)2 and humic acid-bounded Pb in soil colloids were elevated after exogenous KDP added. Our results indicated that there was a mobilization effect of KDP on Pb by increasing the amount of colloidal Pb in soil solution, especially in acid silty clay loam paddy soil. Such colloid-facilitated transport might promote the uptake of Pb in rice and pose a potential threat to human health.


Assuntos
Chumbo/química , Fosfatos/química , Compostos de Potássio/química , Poluentes do Solo/química , Solo/química , Agricultura , Argila/química , Chumbo/análise , Oryza/metabolismo , Poluentes do Solo/análise
17.
Molecules ; 24(19)2019 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-31547080

RESUMO

The manuscript presents the results of the development of new material for high-level waste (HLW) management: the magnesium potassium phosphate (MKP) compound. The possibility of using zeolite (Sokyrnytsya deposit) to increase the mechanical, thermal, and hydrolytic resistance of this compound with immobilized HLW was studied. The main component of the used natural zeolite is a mineral of the clinoptilolite-heulandite series, and quartz, microcline, and clay minerals (illite, sepiolite, and smectite) are present as impurities. The compressive strength of the compound, containing at least 4.2 wt % zeolite, is about 25 MPa. Compound containing 28.6 wt % zeolite retains high compressive strength (at least 9.0 MPa), even after heat treatment at 450 °C. The adding of zeolite to the composition of the compound increases its hydrolytic stability, while the leaching rate of the mobile nuclides 137Cs and 90Sr decreases up to one order of values. Differential leaching rate of radionuclides from the compound containing 28.6 wt % zeolite is 2.6 × 10-7 for 137Cs, 2.9 × 10-6 for 90Sr, 1.7 × 10-9 for 239Pu, and 2.9 × 10-9 g/(cm2∙day) for 241Am. Thus, the properties of the resulting compound correspond to the requirements for solidified HLW in Russia.


Assuntos
Césio/química , Magnésio/química , Fosfatos/química , Plutônio/química , Compostos de Potássio/química , Estrôncio/química , Zeolitas/química
18.
Chemosphere ; 236: 124399, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31548172

RESUMO

Nonylphenol (NP) and nonylphenol monoethoxylate (NP1EO) have toxic and persistent characteristics, and are incompletely degraded in conventional wastewater treatment processes. These compounds are present in sewage sludge that can be reused as fertilizers or soil conditioners. Accordingly, NP and NP1EO should be properly removed before being discharged in the environment. In this study, potassium ferrate (K2FeO4) containing hexavalent iron (Fe(VI)) was used as an environment-friendly oxidizing agent to mediate NP and NP1EO degradation. The aim of this study was to investigate the effects of pH and Fe(VI) dosage on the degradation of NP and NP1EO in water and anaerobically digested sewage sludge samples. In water samples, under conditions examined in this study, maximum removal efficiencies for NP and NP1EO were 98% and 92%, respectively. For digested sewage sludge samples, the maximum removal efficiencies of NP and NP1EO were 58% and 96%, respectively. The results demonstrated that Fe(VI) can potentially degrade NP and NP1EO in water and digested sewage sludge samples. However, organic matter as a matrix in the sludge sample would inhibit the degradation of NP and NP1EO by Fe(VI). The pH values before and after adding K2FeO4 to the samples had an obvious influence on the removal of NP and NP1EO.


Assuntos
Ferro/química , Fenóis/química , Esgotos/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química , Anaerobiose , Concentração de Íons de Hidrogênio , Compostos de Ferro/química , Fenóis/análise , Compostos de Potássio/química , Águas Residuárias/química , Poluentes Químicos da Água/análise
19.
Chemosphere ; 237: 124547, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31549659

RESUMO

Novel ZnS-ZnFe2O4 composites were successfully synthesized via a simple and green hydrothermal route. X-ray diffraction (XRD) patterns of the synthesized composite proved the presence of both ZnS and ZnFe2O4. The other characteristics of the composites were further characterized in detail using Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (UV-vis DRS) and vibrating sample magnetometry (VSM). The performance of ZnS-ZnFe2O4 in the presence of persulfate (PS, K2S2O8) as a co-catalyst was tested for degrading rhodamine B (RhB) under UV light illumination. ZnS-ZnFe2O4 composites could remove about 97.67% of RhB in 90 min, which was much higher removal than either ZnS or ZnFe2O4 alone. Moreover, the recovery of catalyst and its recycling performance were found to be good after testing three times. A feasible mechanism analysis of RhB degradation was validated by simple classical quenching experiments. The enhanced performance was attributed to the high-efficiency separation rate of photo induced electron-hole pairs and highly active free radicals of O2-, OH and SO4-.


Assuntos
Nanopartículas Metálicas/química , Compostos de Potássio/química , Rodaminas/química , Sulfatos/química , Catálise , Compostos Ferrosos/química , Corantes Fluorescentes/química , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Fotólise , Reprodutibilidade dos Testes , Sulfetos/química , Raios Ultravioleta , Difração de Raios X , Compostos de Zinco/química
20.
Biosens Bioelectron ; 144: 111676, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31522100

RESUMO

The point of fabricating ultrasensitive electrochemiluminescence (ECL)-based biosensors should be focused on how to maintain high immune recognition of antigens by antibodies in whole process. That is not effortless due to the structure of the protein can be destroyed root in toxic nanocarriers, excessive cyclic potential and superoxide radicals in coreactant, all of which can lead to reduce the bioactivity of antigen and antibody. In this work, the effect of negative voltage and divers coreactant on protein bioactivity were verified. Based on that, a motivated ECL biosensor with good biocompatibility was fabricated for procalcitonin (PCT) detection using Au nanoclusters (Au NCs) as low-potential cathodic luminophor and K2S2O8 as non-toxic coreactant, respectively. Besides, highly-branched Cu2O was utilized to catalyze K2S2O8 and produce more radical anion SO4•-, which can oxidize Au NCs•- to generate more high-energy-state Au NCs*, thus doubling the ECL intensity to meet the requirements of trace analysis. In addition, protein A (PA) as specific antibody capturer was employed to bind the Fc region of anti-PCT in an orientated way, further maintaining the physiological activity of antibody. As expected, all strategies undoubtedly practically improved the immune recognition of the biosensor and reduced the detection limit to 2.90 fg/mL.


Assuntos
Técnicas Biossensoriais , Técnicas Eletroquímicas , Nanopartículas Metálicas/química , Pró-Calcitonina/isolamento & purificação , Anticorpos/química , Antígenos/química , Catálise , Ouro/química , Limite de Detecção , Medições Luminescentes , Compostos de Potássio/química , Pró-Calcitonina/química , Sulfatos/química
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