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1.
J Agric Food Chem ; 67(33): 9203-9209, 2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31369261

RESUMO

With the monitoring of hundreds of pesticides in food and feed, the comminution step is equally crucial as any other to achieve valid results. However, sample processing is often underestimated in its importance and practical difficulty to produce consistent test portions for analysis. The scientific literature is rife with descriptions of microextraction methods, but ironically, sample comminution is often ignored or dismissed as being prosaic, despite it being the foundation upon which the viability of such techniques relies. Cryogenic sample processing using dry ice (-78 °C) is generally accepted in practice, but studies have not shown it to yield representative test portions of <1 g. Remarkably, liquid nitrogen has rarely been used as a cryogenic agent in pesticide residue analysis, presumably as a result of access, cost, and safety concerns. However, real-world implementation of blending unfrozen bulk food portions with liquid nitrogen (-196 °C) using common food processing devices has demonstrated this approach to be safe, simple, fast, and cost-effective and yield high-quality results for various commodities, including increased stability of labile or volatile analytes. For example, analysis of dithiocarbamates as carbon disulfide has shown a significant increase of thiram recoveries (up to 95%) using liquid nitrogen during sample comminution. This perspective is intended to allay concerns among working laboratories about the practical use of liquid nitrogen for improved sample processing in the routine monitoring of pesticide residues in foods and feeds, which also gives promise for feasible test sample size reduction in high-throughput miniaturized methods.


Assuntos
Ração Animal/análise , Contaminação de Alimentos/análise , Liofilização/métodos , Resíduos de Praguicidas/análise , Gelo-Seco , Liofilização/instrumentação , Frutas/química , Nitrogênio/química
2.
Top Curr Chem (Cham) ; 377(4): 20, 2019 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-31273478

RESUMO

Form a green and sustainable chemistry point of view, cross-dehydrogenative coupling (or oxidative cross-coupling) reactions have been recognized as environmentally sustainable and atom economical synthetic routes for the construction of new carbon-carbon and carbon-heteroatom bonds, since no pre-functionalization of starting materials is required. In the past few years, the direct coupling of sp-hybridized C-H bonds with heteroatom-H bonds has received much attention because of the importance of heteroatom-substituted alkynes in organic and medicinal chemistry. This review examines the recent developments in cross-dehydrogenative coupling reactions between C(sp)-H and X-H (X = N, P, S, Si, Sn) bonds, with a particular focus on the mechanistic aspects of the reactions.


Assuntos
Alquinos/química , Carbono/química , Hidrogênio/química , Hidrogenação , Nitrogênio/química , Fósforo/química , Silício/química , Enxofre/química , Estanho/química
3.
Chem Biodivers ; 16(8): e1900205, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31294527

RESUMO

The importance of phenolic compounds for responding to various environmental conditions has been widely emphasized. However, the role of interactions between polyphenols and ecological factors, especially C, N, and P stoichiometry was little studied. Here, 15 sites across five provinces of Pinus bungeana in temperate regions of China were studied. The results showed that the higher values of total phenolic contents (TPC) of leaf and litter were distributed among the north distribution area of P. bungeana, lower values were in the south, whereas soil TPC were contrary to leaf and litter TPC. The stepwise regression, path analysis and decision index of path analysis for leaf TPC and ecological factors showed that altitude had the most direct impact on leaf TPC. Moreover, the principal determinants of leaf, litter and soil TPC were soil C/P ratios, longitude, and soil N/P ratios, respectively. In addition, the leaf, litter and soil TPC of P. bungeana were limited by soil C/N ratios, mean annual temperature, and soil P, respectively. Overall, our study provided evidence that ecological factors affected strongly the leaf, litter and soil TPC of P. bungeana.


Assuntos
Pinus/química , Polifenóis/química , Solo/química , Carbono/química , China , Colorimetria , Ecossistema , Nitrogênio/química , Fósforo/química , Pinus/metabolismo , Folhas de Planta/química , Folhas de Planta/metabolismo , Polifenóis/análise , Temperatura Ambiente
4.
J Photochem Photobiol B ; 197: 111545, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31326847

RESUMO

Proper waste utilization in order to promote value added product is a promising scientific practice in recent era. Inspiring from the recurring trend, we propose a single step oxidative pyrolysis derived fluorescent carbon dots (C-dots) from Allium sativum peel, which is a natural, nontoxic, and waste raw material. Because of its excellent optical properties, and photostability this C-dots have been used in versatile area of applications. Due to its immediate water dispersing character, C-dots reinforced Poly(acrylic acid) (PAA) films revealed improvement in uniaxial stretching behavior and can be used as transparent sunlight conversion film. The nanocomposite film has been tested against rigorous simulated sunlight which proved almost identical sunlight conversion behavior with no photo-bleachable character which is definitely added an extra quality of transparent polymer films. Moreover, the C-dots dispersion has been used as in vitro biomarker for living cells owing to its ease in solubility, biocompatibility, non-cytotoxicity and bright fluorescence even in subcutaneous environment. For this case, adipose derived mesenchymal stem cells (ADMSCs) have been chosen and injected to rabbit ear skin to perform two-photon imaging experiment. The present work opens a new avenue towards the large-scale synthesis of bio-waste based fluorescent C-dots, paving the way for their versatile applications.


Assuntos
Allium/química , Nitrogênio/química , Fotodegradação/efeitos da radiação , Pontos Quânticos/química , Enxofre/química , Luz Solar , Resinas Acrílicas/química , Tecido Adiposo/citologia , Allium/metabolismo , Animais , Materiais Biocompatíveis/química , Carbono/química , Sobrevivência Celular/efeitos dos fármacos , Frutas/química , Frutas/metabolismo , Química Verde , Masculino , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/efeitos dos fármacos , Células-Tronco Mesenquimais/metabolismo , Microscopia de Fluorescência , Pontos Quânticos/toxicidade , Coelhos , Pele/efeitos dos fármacos , Pele/patologia , Solubilidade
5.
Anal Chim Acta ; 1078: 125-134, 2019 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-31358210

RESUMO

We synthesized three kinds of nitrogen-doped nanoporous carbon nanomaterials (represented by N-mC) through a cost-effective method, that is, pyrolysis of plant biomasses (grass, flower, and peanut shells). We further explored their potential as sensitive bioplatforms for electrochemical label-free aptasensors to facilitate the early detection of alpha-fetoprotein (AFP). Chemical structure characterizations revealed that rich functional groups coexisted in as-synthesized N-mC nanomaterials, such as C-C, C-O, C=O, C-N, and COOH. Among the three kinds of N-mC nanomaterials, the one derived from grass (N-mCg) exhibited the lowest carbon defect degree, the highest ID/IG ratio in the Raman spectra, and the largest specific surface area (186.2 m2 g-1). Consequently, N-mCg displayed excellent electrochemical activity and strong affinity toward aptamer strands, further endowing the corresponding aptasensor with sensitive detection ability for AFP. Electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) were used to investigate the whole detection procedure for AFP. The EIS and DPV results showed that the fabricated N-mCg-based aptasensor possessed an extremely low limit of detection of 60.8 and 61.8 fg·mL-1 (s/n = 3), respectively, for detecting AFP within a wide linear range from 0.1 pg mL-1 to 100 ng mL-1. Moreover, the aptasensor displayed acceptable selectivity and applicability, high reproducibility, and excellent stability in serum samples of cancer patients. Therefore, the proposed cost-effective and label-free strategy based on the nitrogen-doped nanoporous carbon derived from plant biomass is a promising approach for the early detection of various tumor markers.


Assuntos
Biomassa , Técnicas Biossensoriais/métodos , Carbono/química , Técnicas Eletroquímicas/métodos , Nanoestruturas/química , alfa-Fetoproteínas/análise , Adolescente , Adulto , Idoso , Aptâmeros de Nucleotídeos/química , Sequência de Bases , Técnicas Biossensoriais/instrumentação , DNA/química , Técnicas Eletroquímicas/instrumentação , Eletrodos , Feminino , Humanos , Limite de Detecção , Masculino , Pessoa de Meia-Idade , Nitrogênio/química , Plantas/química , Porosidade , Reprodutibilidade dos Testes , Adulto Jovem
6.
Bioresour Technol ; 289: 121754, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31323714

RESUMO

Acetonitrile (ACN) is a very volatile, toxic and nitrogen-rich organic compound. To enhance ACN wastewater treatment, a novel hybrid membrane-aerated bioreactor (MAB) containing aerated and non-aerated zones was established. A polypropylene hollow fiber membrane module (HF) and a silicone rubber membrane module (SR) were separately used as the bubble-free aeration diffuser and the biofilm carrier, and the non-aerated zones of these two types of reactors were packed with ceramsite. When the influent ACN loading was 1.200 kg/m3·d, under aeration pressures of 20 kPa in the HF-MAB and 40 kPa in the SR-MAB, ACN removal loadings of 1.116 kg/m3·d and 1.004 kg/m3·d, respectively, were achieved, and the TN (total nitrogen) removal loadings were 0.267 kg/m3·d and 0.246 kg/m3·d, respectively. In the MABs, different stratified biofilm structures of the two zones and the diffusion and counter-diffusion of oxygen synergistically promoted ACN degradation, nitrification and denitrification.


Assuntos
Reatores Biológicos , Águas Residuárias/química , Acetonitrilos/metabolismo , Biofilmes , Análise da Demanda Biológica de Oxigênio , Desnitrificação , Nitrificação , Nitrogênio/química , Oxigênio/metabolismo , Eliminação de Resíduos Líquidos
7.
J Chromatogr A ; 1602: 168-177, 2019 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-31303311

RESUMO

In this work, we presented the preparation of magnetic carbon nanotubes (MCNTs) functionalized with molecularly imprinted polymers (MIPs) for effective removal of aristolochic acid I (AAI) in traditional Chinese medicine (TCM). MCNTs@AAI-MIPs was obtained via a facile and environmental friendly sol-gel process. Firstly, MCNTs were synthesized by a solvothermal method. Then, the template molecules were self-assembled with the functional monomer phenyltrimethoxysilane (PTMOS) in the presence of ethanol and water. Finally, AAI-MIPs film was coated on the MCNTs to obtain product MCNTs@AAI-MIPs using tetraethyl-orthosilicate (TEOS) as cross-linker. The morphology and structure of prepared MIPs were characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray diffraction (XRD), nitrogen gas adsorption and vibrating sample magnetometer (VSM). The adsorption properties were demonstrated by kinetic, isothermal and selective adsorption experiments. The results showed that the imprinted nanocomposites exhibited fast separation rate (10 s), high adsorption capacity (18.54 µg∙mg-1), short kinetic equilibrium time (15 min), and good selectivity to template molecule with imprinting factor (IF) of 3.17. A regression equation (y=57294x-4734.1) with good linearity was obtained in the concentration range of 0.1-200 µg∙mg-1 for AAI with a correlation coefficient (R2) of 0.9998. The limit of detection (LOD, S/N=3) was 0.034 µg∙mg-1. Moreover, high recoveries ranged from 80% to 110% (RSD=3.27%-8.16%) were received in spiked TCM samples. The results suggested that the proposed MCNTs@AAI-MIPs could efficiently and specifically capture AAI from an actual complex TCM samples.


Assuntos
Ácidos Aristolóquicos/isolamento & purificação , Magnetismo , Impressão Molecular/métodos , Nanotubos de Carbono/química , Polímeros/química , Adsorção , Cinética , Nanotubos de Carbono/ultraestrutura , Nitrogênio/química , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura Ambiente , Difração de Raios X
8.
Environ Sci Pollut Res Int ; 26(22): 22990-23001, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31183755

RESUMO

The aim of this meta-analysis was to synthesize the effects of biochar amendment on soil enzyme activities (SEAs) related to carbon (C), nitrogen (N), and phosphorus (P) cycling. Based on 401 paired comparisons from 43 published studies, the SEAs and main influential factors were analyzed in response to biochar characteristics, soil properties, and experiment conditions. Results showed that biochar additions to soils overall increased the N- and P-cycling SEAs by 14 and 11%, respectively. The enhancement of the N- and P-cycling SEAs was mainly attributable to the microbial stimulation by biochar properties (i.e., nutrient content and porosity) and soil nutrients (e.g., soil organic C and total N). The enhancement was the most significant under the conditions with biochars produced at low temperatures and using feedstock materials with high nutrient content, and biochar applications in acidic or neutral soils, coarse or fine soils, and farmland soils. Biochar additions to soils overall reduced the C-cycling SEAs by 6.3%. The C-cycling SEAs were greatly suppressed under the conditions with low and very high biochar loads, biochars produced at high temperatures and with feedstock materials of herb and lignocellulose, and biochar applications in alkaline, fine, and forest soils. The results were mainly related to the adsorption and inhibition effects of biochars and soil properties (e.g., liming effect, high biochar porosity and aromatic C content) on fungi and the enzymes. Biochar feedstock, C/N and load, and soil total N were the main influential factors on the SEAs. The results from this study demonstrate that biochar amendment is beneficial to improving soil N and P cycling and C sequestration.


Assuntos
Carbono/química , Carvão Vegetal/química , Nitrogênio/análise , Adsorção , Nitrogênio/química , Fósforo , Solo
9.
Environ Sci Pollut Res Int ; 26(22): 22971-22978, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31183756

RESUMO

The electrochemical conversion of inorganic nitrogen forms (i.e., NO3--N, NO2--N, and NH4+-N) to N2 was studied using Ti as cathode and Ti/PbO2 as anode in the simulated wastewater. According to linear sweep voltammetry, nitric nitrogen was effectively converted to N2 on Ti cathode at the working potential more negative than - 1.1 V (vs. SCE). Ti/PbO2 anode had the working potential of + 0.8 V (vs. SCE) for NH4+-N converted to N2. The apparent rate constants of NO3--N to NO2--N and NO2--N to N2 were 2.46 × 10-2 min-1 and 4.03 × 10-2 min-1, respectively. The kinetic analyses revealed that the reduction of NO3--N was a two-step process, and NO2--N was an unstable intermediate, which could be easily oxidized to NO3--N or reduced to NH4+-N. The majority of NH4+-N could be effectively converted to N2 on Ti/PbO2 anode with the apparent rate constants of 5.12 × 10-2 min-1. The dual-chamber (DC) reactor with circulation was used in the batch electrolysis of simulated and actual wastewater. The results verified the pathways of NH4+-N oxidation and NO3--N reduction and achieved high conversion rate of total nitrogen (TN) to N2.


Assuntos
Nitrogênio/química , Titânio/química , Eletrodos , Eletrólise , Cinética , Oxirredução
10.
Croat Med J ; 60(3): 265-272, 2019 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-31187955

RESUMO

AIM: To assess the effect of air, gas mixture composed of 50% nitrogen and 50% oxygen (nitrox 50), or gas mixture composed of 1% nitrogen and 99% oxygen (nitrox 99) on bubble formation and vascular/endothelial function during decompression after self-contained underwater breathing apparatus diving. METHODS: This randomized controlled study, conducted in 2014, involved ten divers. Each diver performed three dives in a randomized protocol using three gases: air, nitrox 50, or nitrox 99 during ascent. The dives were performed on three different days limited to 45 m sea water (msw) depth with 20 min bottom time. Nitrogen bubbles formation was assessed by ultrasound detection after dive. Arterial/endothelial function was evaluated by brachial artery flow mediated dilatation (FMD) before and after dive. RESULTS: Nitrox 99 significantly reduced bubble formation after cough compared with air and nitrox 50 (grade 1 vs 3 and vs 3, respectively, P=0.026). Nitrox 50 significantly decreased post-dive FMD compared with pre-dive FMD (3.62 ± 5.57% vs 12.11 ± 6.82% P=0.010), while nitrox 99 did not cause any significant change. CONCLUSION: Nitrox 99 reduced bubble formation, did not change post-dive FMD, and decreased total dive duration, indicating that it might better preserve endothelial function compared with air and nitrox 50 dive protocols.


Assuntos
Doença da Descompressão/prevenção & controle , Descompressão/métodos , Mergulho/fisiologia , Endotélio Vascular/fisiopatologia , Nitrogênio/uso terapêutico , Oxigênio/uso terapêutico , Adulto , Ar , Artéria Braquial/fisiopatologia , Doença da Descompressão/diagnóstico por imagem , Doença da Descompressão/fisiopatologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Nitrogênio/química , Oxigênio/química , Ultrassonografia , Vasodilatação
11.
Plant Physiol Biochem ; 141: 122-132, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31151078

RESUMO

Most of the hot spots about rice research are related to roots; increasing rice yield is mainly associated with improving root traits. Understanding phenotype-gene regulation relationship in different rice cultivars can contribute to the genetic improvement of root system. The expression pattern of root genes in moroberekan (deep and thick roots and high root/shoot ratio "R/S") was compared to that in Giza178 and PM12 (numerous but shallow roots) and IR64 (fewer but deeper roots than the latter ones). In contrast to the other genotypes, moroberekan did not cease developing deep and thick roots even after 60 days from sowing, perhaps because of not only the consistent upregulation but also the interaction of root genes. Xylem sap flow was significantly higher even under drought (low water content) in moroberekan. Auxin signaling-related ARF12 and PIN1 genes could play key roles in improving root traits in response to low water or nitrogen content. Their concurrent upregulation was coincided with developing 1) deeper roots in moroberekan under drought, 2) thicker and deeper roots in PM12 under low nitrogen content (LN) and 3) new roots with thicker and deeper characteristics in the four genotypes after root trimming. The upregulation of PIN1 or ARF12 in Giza178 at LN, PM12 at drought or in IR64 under drought or LN did not greatly change the root traits. Hierarchical analysis showed that ARF12 and PIN1 were distantly related, but overlapped with other genes controlling root traits. Overexpression of ARF12 and PIN1 could improve root traits in rice cultivars.


Assuntos
Regulação da Expressão Gênica de Plantas , Nitrogênio/química , Oryza/genética , Oryza/fisiologia , Raízes de Plantas/fisiologia , Água/química , Análise por Conglomerados , Secas , Perfilação da Expressão Gênica , Genes de Plantas , Genótipo , Fenótipo , Locos de Características Quantitativas
12.
Food Chem ; 295: 530-536, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31174792

RESUMO

In this work, new detection route for ascorbic acid was designed. First, highly luminescent sulfur and nitrogen doped graphene quantum dots (S,N-GQDs) were prepared via simple hydrothermal method using citric acid and thiourea as the C, N and S sources respectively. The prepared S,N-GQDs are characterized by XRD, HRTEM, FTIR, EDS and PL. Investigations showed that prepared S,N-GQDs have a good photostability and excitation-dependent emission fluorescence. Prepared S,N-GQDs showed maximum excitation wavelength and emission wavelength at 400 and 462 nm, respectively. In the following, prepared S,N-GQDs were applied as a photoluminescence probe for detection of ascorbic acid (AA). The designed sensor was based on "off-on" detection mode. The developed sensor had a linear response to AA over a concentration range of 10-500 µM with a detection limit of 1.2 µM. The regression equation is Y = 0.0014 X + 1.2036, where Y and X denote the fluorescence peak intensity and AA concentration, respectively.


Assuntos
Ácido Ascórbico/análise , Grafite/química , Pontos Quânticos/química , Espectrometria de Fluorescência/métodos , Limite de Detecção , Nanoestruturas/química , Nitrogênio/química , Enxofre/química
13.
Plant Physiol Biochem ; 141: 466-476, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31252252

RESUMO

The present study was aimed to investigate adaptation in physiology and biochemistry of Solanum lycopersicum seedlings under NaCl (NaCl0; 0.0 g NaCl kg-1 sand, NaCl1; 0.3 g NaCl/kg sand and NaCl2; 0.5 g NaCl/kg sand) stress, simultaneously supplemented with different (deprived; 0 mg/kg sand, LN; 105 mg/kg sand, MN; 210 mg/kg sand and HN; 270 mg/kg sand) levels of nitrogen (N). NaCl at both doses caused significant loss in growth, K+ content, K+/Na+ ratio, total chlorophyll and photosynthetic oxygen evolution. Further, N supplementation influences growth of test seedlings, that attained maximum growth in HN followed by MN, LN and deprived N conditions. N at HN level significantly declined Na+ accumulation in the cell and enhanced level of K+. NaCl treatment enhanced level of oxidative stress biomarkers: superoxide radical (O2•-), hydrogen peroxide (H2O2), MDA equivalents contents and electrolyte leakage in leaf as well as root despite enhanced activity of SOD, POD, CAT and GST, and enzymes participating in the ascorbate-glutathione cycle (AsA-GSH cycle) viz. APX, DHAR and GR. At the same time, higher contents of total AsA (AsA + DHA) and total GSH (GSH + GSSG), and maintained ratios of AsA/DHA and GSH/GSSG in HN fed seedlings were observed. Overall, the results suggest that HN supplementation was able in alleviating NaCl induced toxicity in test seedlings which was mainly due to the up-regulation of the AsA-GSH cycle, K+ and K+/Na+ ratio, which resulted into better growth performance of HN fed seedlings under NaCl stress while reverse was noticed for LN and deprive N conditions.


Assuntos
Lycopersicon esculentum/metabolismo , Nitrogênio/química , Espécies Reativas de Oxigênio/metabolismo , Salinidade , Antioxidantes/metabolismo , Ácido Ascórbico/metabolismo , Biomarcadores/metabolismo , Clorofila/metabolismo , Glutationa/metabolismo , Peróxido de Hidrogênio/metabolismo , Peroxidação de Lipídeos , Malondialdeído/metabolismo , Estresse Oxidativo , Oxigênio/metabolismo , Fotossíntese , Pigmentação , Folhas de Planta/metabolismo , Raízes de Plantas/metabolismo , Brotos de Planta/metabolismo , Potássio/química , Plântula/metabolismo , Cloreto de Sódio/química
14.
Environ Sci Pollut Res Int ; 26(22): 23095-23107, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31183761

RESUMO

Nitrous oxide (N2O) generated during biological nitrogen removal in wastewater treatment processes has contributed an important proportion to the global warming effect. To evaluate the possibility of N2O emission mitigating by changing carbon source supply strategies, nitrogen transformation characteristics and N2O emissions with methanol one-time dosing and step dosing were investigated. Two sets of laboratory-scale sequencing batch biofilm reactors (SBBRs) were conducted to treat real domestic wastewater with low carbon source. The results revealed that reactors with methanol step dosing showed a lower N2O emission of 0.0402 ± 0.0016 mg/(L·h), together with a higher total nitrogen and ammonia nitrogen removal efficiencies of 83.30% ± 1.21 and 93.45% ± 1.20, respectively. While N2O emission from conventional one-time dosing reactors was 0.0741 ± 0.0025 mg/(L·h), total nitrogen and ammonia nitrogen removal efficiencies were 75.71% ± 0.54 and 88.45% ± 0.59, respectively. The N2O emission factor of SBBR was reduced from 6.26% ± 0.21 to 3.40% ± 0.14 with methanol step dosing. Moreover, nitrification rates in aerobic phases were reduced, while denitrification rates in anoxic phases were elevated. Hence, carbon source step dosing enhanced nitrogen removal and reduced N2O emission compared with one-time dosing, which is a simply achievable strategy for N2O emission reduction in highly automated systems like wastewater treatment plants.


Assuntos
Amônia/química , Carbono/química , Nitrogênio/química , Óxido Nitroso/análise , Águas Residuárias/análise , Biofilmes/efeitos dos fármacos , Reatores Biológicos , Desnitrificação , Nitrificação , Óxido Nitroso/química
15.
Environ Sci Pollut Res Int ; 26(22): 23082-23094, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31187376

RESUMO

Layered combined bio-ceramic, zeolite, and anthracite were used as substrates in vertical-flow constructed wetlands (VFCWs) for enhancing contaminant removal from synthetic municipal wastewater. Plant growth and propagation and the removal of organic matter, nitrogen, and phosphorus as well as its spatiotemporal variation were evaluated systematically. The results demonstrated that three different substrates were adequate for the establishment of Canna indica L., especially for zeolite. All small-scale VFCW units were simultaneous efficient in removing CODCr (73.9-78.7%), NH4+-N (83.8-89.9%), TN (88.3-91.5%), SRP (93.8-98.6%), and TP (87.1-90.9%) with a little significant difference on treatment performance. Different pollution removal processes followed a different trend because of their different removal mechanisms driven by the synergy of substrate, plant, and microorganism. Purification space moved down due to the adsorption capacity consumption of upper layer substrate over time. It was concluded that VFCWs filled with layered combined bio-ceramic, zeolite, and anthracite had great potential for treating municipal wastewater.


Assuntos
Nitrogênio/análise , Fósforo/análise , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Zeolitas/química , Carvão Mineral , Nitrogênio/química , Fósforo/química , Desenvolvimento Vegetal , Áreas Alagadas , Zingiberales
16.
Chemosphere ; 233: 207-215, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31173958

RESUMO

Rain garden is a typical facility with many applications in urban low impact development (LID). It plays an important role in regulating runoff water quantity and quality. Two rain gardens with the discharge ratios of 20:1 and 15:1 were used as studied facilities. Seven soil sampling events were conducted from April 2017 to February 2019 to study the influences of stormwater concentration infiltration in rain gardens on soil nitrogen (N), phosphorus (P) and TOC and their relations with enzymes. The results showed that the contents of soil TN and NO2-N + TON in gardens gradually decreased with time, while those of NH3-N and TP increased with time. The content of NO3-N varied greatly with time, and there was no obvious rule. TOC increased first and then decreased. Vertical distributions of N, P and TOC showed that the contents of NH3-N, NO2-N + TON and TN at 0-50 cm were high, so the upper soil was the sensitive area to the influence of stormwater concentration infiltration in rain gardens. The content of NH3-N decreased gradually with the increase of soil depth, but those of NO3-N and TP increased with the soil depth. Therefore, NO3-N and TP migrated down with water infiltration in soil, and preventing NO3-N and P leaching was critical for effective N and P removal though rain gardens. Soil urease (SU), sucrose (SS), protease (SP) and acid phosphatase (SAP) had a good linear relationship with N, P and TOC, and R2were all greater than 0.5.


Assuntos
Carbono/química , Enzimas/metabolismo , Nitrogênio/análise , Fósforo/análise , Solo/química , Carbono/análise , China , Monitoramento Ambiental , Enzimas/química , Jardins , Nitrogênio/química , Fósforo/química , Chuva
17.
Environ Sci Pollut Res Int ; 26(22): 22431-22449, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31154652

RESUMO

We investigated the treatment efficiency of micro-polluted NO3--dominated river water with low C/N ratio by five parallel pilot-scale IVCWs with different plant and substrate collocation. When the mean concentration was 2.24 and 0.193 mg L-1 in influent, IVCWs achieved an average (mass) removal rate of (0.09 g m-2 day-1) 46.8% and (0.77 g m-2 day-1) 62.3% for TN and TP, respectively, during 1 year of operation. Water quality was significantly improved from grade V to meet the criterion of grade IV of surface water. Through the comparison of removal rate by different IVCWs, we found that lack of carbon sources in influent limited the denitrification in the middle and bottom layers (ML, BL) of IVCW. Zeolites deployed in the upper layer (UL) of IVCW reduced the overall N removal efficiency compared with gravels, due to a stronger nitrification but weaker denitrification. Canna indica (C. indica) was superior to Arundo donax (A. donax) and Thalia dealbata (T. dealbata) for N removal in the UL of IVCW due to higher aboveground biomass accumulation and microbial removal during the first 10 months. Stronger nitrification and denitrification were simultaneously facilitated near the rhizosphere of C. indica. When entered into Dec., A. donax performed higher N removal efficiency than the other two species. The internal replenishment of peats in the ML as carbon sources significantly improved N and P removal efficiency. Zeolites with stronger capacity of ammonium (NH4+) adsorption was more in favor of anammox in the BL, when compared with roseites, but both of them were not conducive to the growth of denitrifiers. However, the deployment of shale ceramisites obtained an opposite result. Gemmata and Pirellula as anammox bacteria were more enriched in the zeolite layer, whereas some anaerobic denitrifiers (Corynebacterium and Paludibacter) and heterotrophic denitrifiers including Bacillus, Geobacter, Pseudomonas, and Lactococcus were more found in shale ceramisite. Supply of peats as carbon sources in the ML was beneficial for the adhesion of anammox bacteria and denitrifiers in the BL of shale ceramisites. An ideal model composed of C. indica + A. donax (DFU)-gravel (UL)-anthracite+peat (ML)-zeolite+shale ceramsite (BL)-Acorus calamus (UFU) was proposed for treating this type of river water to achieve high efficiency.


Assuntos
Carbono/química , Nitrogênio/química , Poaceae/química , Zeolitas/química , Adsorção , Bactérias , Carbono/análise , China , Desnitrificação , Nitrificação , Nitrogênio/análise , Projetos Piloto , Rios , Poluição da Água , Áreas Alagadas
18.
Talanta ; 200: 186-192, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31036172

RESUMO

In this work, different paper surface modification strategies were compared to obtain an amine functionalized SBA-15 (N-SBA-15) composite for paper-based device development. The synthesized N-SBA-15 was characterized by N2 adsorption-desorption isotherm, and infrared spectroscopy (FTIR), and it was incorporated to different polymer matrices (κ-carrageenan (CA), polyvinyl alcohol (PVA) and polyethylenimine (PEI)) for the development of the composite modified paper-based device. The retention, interactions, and morphology of the obtained composites were investigated by absorbance measurement, FTIR and scanning electron microscopy (SEM), respectively. To demonstrate the applicability of the modified paper-based device, ascorbic acid (AA) quantification was carried out. Horseradish peroxidase (HRP) was immobilized onto the modified paper surface. HRP in the presence of H2O2 catalyzes the oxidation of 10-acetyl-3,7-dyhidroxyphenoxazine (ADHP) to highly fluorescent resorufin, which was measured by LIF detector. Thus, when AA was added to the solution, it decreases the relative fluorescence signal proportionally to the AA concentration. The linear range from 50 nmol L-1 to 1500 nmol L-1 and a detection limit of 15 nmol L-1 were obtained for AA quantitation. The obtained results allowed us to conclude that N-SBA-15/PEI composite could be considered an excellent choice for the paper-based device modification procedure due to its inherent simplicity, low cost, and sensitivity.


Assuntos
Ácido Ascórbico/análise , Papel , Polímeros/química , Dióxido de Silício/química , Adsorção , Peroxidase do Rábano Silvestre/química , Peroxidase do Rábano Silvestre/metabolismo , Peróxido de Hidrogênio/química , Nitrogênio/química , Tamanho da Partícula , Dióxido de Silício/síntese química , Espectroscopia de Infravermelho com Transformada de Fourier , Propriedades de Superfície
19.
Ultrason Sonochem ; 56: 430-436, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31101281

RESUMO

We report a facile and ultrasound assisted sonochemical synthesis of a Tungsten disulfide nanorods decorated nitrogen-doped reduced graphene oxide based nanocomposite. The WS2 NRs/N-rGOs nanocomposite was characterized by FESEM, HRTEM, XRD, XPS and electrochemical methods and its application towards the electrochemical detection of organo-arsenic drug (coccidiostat). The WS2 NRs/N-rGOs modified SPCE was used for the electrochemical reduction of roxarsone (ROX) and it showed superior electrocatalytic performance in terms of reduction peak current and shift in overpotential when compared to those of WS2 NRs/SPCE, N-rGOs/SPCE and based SPCE. The WS2 NRs/N-rGOs modified SPCE showed an excellent sensing ability towards ROX in nitrogen saturated phosphate buffer (PB) then the other controlled modified and unmodified electrodes. The WS2 NRs/N-rGOs/SPCE displays high sensitive response towards ROX and gives wide linearity in the range of 0.1-442.6 µM ROX in neutral phosphate buffer (pH 7.0) and the sensitivity of the sensor is calculated as 14.733 µA µM-1 cm-2. The WS2 NRs/N-rGOs nanocomposite modified sensor also exhibits valuable ability of anti-interference to electroactive analytes. Furthermore, the as-prepared WS2 NRs/N-rGOs/SPCE has been applied to the determination of ROX in biological and pharmaceutical samples.


Assuntos
Antibacterianos/análise , Eletroquímica/instrumentação , Grafite/química , Limite de Detecção , Nanotubos/química , Nitrogênio/química , Roxarsona/análise , Antibacterianos/química , Catálise , Técnicas de Química Sintética , Eletrodos , Concentração de Íons de Hidrogênio , Cinética , Porosidade , Roxarsona/química
20.
Food Chem ; 294: 194-202, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31126453

RESUMO

The changes in physico-chemical and rheological properties of kithul starch by the impact of energetic neutral nitrogen atoms produced by the glow discharge air plasma with novel technique were analysed. Here, treatment was carried out at different power levels (5 W & 15 W) and treatment time (30 min & 60 min). Decrease in amylose and moisture content and increase in swelling index and solubility of plasma treated kithul starch were observed. Fourier transform infrared spectra of plasma treated starch showed variation in the peaks corresponding to CH2 and OH groups. Relative crystallinity significantly (p ≤ 0.05) decreased after plasma treatment. Scanning electron microscopy showed severe damages on the starch granular surface by the effect of energetic neutral nitrogen atoms. Pasting properties increased and thermal properties showed significant (p ≤ 0.05) changes after plasma treatment. Storage modulus (G') and loss modulus (G″) reduced at higher levels of plasma power and it indicated to its weak gel formation.


Assuntos
Nitrogênio/química , Gases em Plasma , Amido/química , Arecaceae/química , Arecaceae/metabolismo , Microscopia Eletrônica de Varredura , Reologia , Solubilidade , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura Ambiente
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