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1.
Food Chem ; 302: 125267, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31400701

RESUMO

A study was to determine the correlation between the fine structure and the physicochemical properties of pre-gelatinized corn starch (PGCS) and the quality of noodles with added PGCS. Drum-dried corn starch (DDCS) and extrusion-cooked corn starch (ECCS) were used. The results revealed that the cold-water viscosity of ECCS and DDCS was about 10 and 100 times greater, respectively, than that of native corn starch (NCS), and the gel strength of DDCS was 1.67 times greater than that of ECCS. The average hydrodynamic radius of whole molecular (R¯h) and Ap were approximately half that of native corn starch in ECCS. Dough sheets prepared with various concentrations of PGCS (5-10%, w/w) had significantly greater tensile strength, and the addition of PGCS significantly increased the smoothness of the cooked noodles. DDCS was better than ECCS for increasing the noodles' processing quality.


Assuntos
Culinária , Qualidade dos Alimentos , Gelatina/química , Amido/química , Farinha/análise , Viscosidade , Água/química
2.
Food Chem ; 303: 125341, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31442898

RESUMO

To find the determining factors for 3-acetyl-deoxynivalenol (3-ADON) deacetylation during wheat-based food production, wheat flours with different heat treatments, different matrixes of the starch-gluten mixture, and different protein fractions (Osborne classification) were evaluated. The deacetylation behavior of 3-ADON was significantly suppressed for heat-treated wheat flours, indicating that heating induced change of the functional or chemical properties of wheat grain components, especially for proteins. Among the different matrixes, only 3% of the 3-ADON in starch was converted to DON, however, this value reached 60-75% for wheat flour. The results showed that proteins were responsible for the deacetylation of 3-ADON. After separation, only albumins mediated the deacetylation of 3-ADON into DON in four protein fractions. The proteins were identified by LC-MS/MS, and the results suggested that cytochrome P450, acetylesterase and histone deacetylase were the potential targeted enzymes that mediated the deacetylation of 3-ADON during dough preparation for wheat-based food production.


Assuntos
Pão/análise , Farinha/análise , Proteínas de Plantas/química , Tricotecenos/química , Triticum/química , Água/química , Glutens/química , Solubilidade , Amido/química
3.
Food Chem ; 303: 125364, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31445176

RESUMO

Lipid oxidation was considered as a problem in food conservation. The present study aims to investigate the effect of lipopeptides DCS1 on the conservation of food models against lipid oxidation by determining the primary and the secondary oxidation products. Lipopeptides DCS1 are able to preserve the nutritional properties of the emulsion during 23 days of storage, at a concentration of 0.0125% (w/w of emulsion), by slowing down the formation of hydroperoxides and malondialdehyde (MDA) compounds. The direct incorporation of lipopeptides in ground beef patties at a concentration of 0.5% (w/w of meat) was found to be more effective than gelatin film enriched with lipopeptides (2.5%, w/w of gelatin) as a coating, in inhibiting lipid oxidation. Furthermore, lipopeptides DCS1 are not toxic to human kidney cells HEK293 up to a concentration of 250 µg/ml. The results indicate that lipopeptides DCS1 are effective for the preservation of fatty foods against lipid oxidation.


Assuntos
Bacillus/química , Lipopeptídeos/farmacologia , Carne Vermelha , Óleo de Girassol/química , Água/química , Animais , Bovinos , Emulsões , Conservação de Alimentos , Células HEK293 , Humanos , Lipídeos/química , Oxirredução/efeitos dos fármacos
4.
Water Res ; 168: 115149, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31604175

RESUMO

Strategically important elements are those that are vital to advanced manufacturing, low carbon technologies and other growing industries. Ongoing depletion and supply risks to these elements are a critical concern, and thus, recovery of these elements from low-grade ores and brines has generated significant interest worldwide. Among the strategically important elements, this paper focuses on rare earth elements (REEs), the platinum-group metals and lithium due to their wide application in the advanced industrial economics. We critically review the current methods such as precipitation, ion exchange and solvent extraction for extracting these elements from low-grade ores and brines and provide insight into the technical challenges to the practical realisation of metal extraction from these low-grade sources. The challenges include the low concentration of the target elements in brines and inadequate selectivity of the existing methods. This review also critically analyzes the potential applicability of an integrated clean water production and metal extraction process based on conventional pressure-driven membrane and emerging membrane technologies (e.g., membrane distillation). Such a process can first enrich the strategically important elements in solution for their subsequent recovery along with clean water production.


Assuntos
Metais Terras Raras , Destilação , Metais , Água
5.
Water Res ; 168: 115108, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31604178

RESUMO

This study addressed the effectiveness of light emitting diodes to achieve inactivation of three different Aspergillus species (Aspergillus fumigatus, Aspergillus niger and Aspergillus terreus) in a real water matrix. Three single small ultraviolet-C diodes emitting light at two different wavelengths were tested: 255 nm that is similar to the wavelength emitted by low pressure mercury lamps and 265 nm that is closer to the maximum absorbance wavelength of DNA. The ultraviolet-C diodes emitting light at 265 nm were found to be more effective than the 255 nm, achieving 3-log, 1-log and 5-log inactivations of Aspergillus fumigatus, Aspergillus niger and Aspergillus terreus using less than 20 mJ/cm2 (13,97 mJ/cm2; 7,28 mJ/cm2; 19,74 mJ/cm2). The diodes have also affected the morphology of the fungal spores and increased the percentage of damaged and dead spores.


Assuntos
Desinfecção , Água , Aspergillus , Raios Ultravioleta , Microbiologia da Água
6.
Water Res ; 168: 115169, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31629231

RESUMO

Nitrite formation during Vacuum UV (VUV) photolysis of nitrate-containing water has been studied in this research. Here the goal was to understand the effect of water matrix, specifically dissolved organic carbon (DOC), dissolved inorganic carbon (DIC) and dissolved oxygen (DO), on the formation of nitrite in nitrate-containing water during treatment with VUV AOP. The results confirmed that the formation of nitrite was considerable during the VUV irradiation, and it increased with increasing the UV fluence. However, the rate of nitrite formation was not linearly correlated with the UV fluence. Also, nitrite formation increased with increasing the DOC in water. Tert-butanol, as OH radical scavenger, was used to elucidate the mechanism behind the impact of DOC. The effect of DIC was only pronounced at very high DIC concentration, which led to lower formation of nitrite. When both DOC and DIC were present in water, DOC had the dominant effect on nitrite formation. DO in water had the impact of reducing the formation of nitrite. All these results can help to understand the mechanisms involved in the transformation of nitrate to nitrite in various water matrices, and guide VUV applications for scientific and industrial proposes.


Assuntos
Nitritos , Água , Carbono , Fotólise , Raios Ultravioleta , Vácuo
7.
Water Res ; 168: 115179, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31639593

RESUMO

The transport of per- and poly-fluoroalkyl substances (PFAS) in the vadose zone is complicated by the fact that multiple mass-transfer processes can contribute to their retention and retardation. In addition, PFAS transport at some sites can be further complicated by the presence of organic immiscible liquids (OIL). Mass-transfer processes are inherently rate limited and, therefore, have the potential to cause nonideal transport of PFAS. The objectives of this research were to: (1) develop a solute-transport model that explicitly accounts for multiple retention processes, including adsorption at air-water and OIL-water interfaces, adsorption by the solid phase, and diffusive mass-transfer between advective and nonadvective domains, and (2) apply the model to measured transport data to delineate which processes are rate limited and contribute to observed nonideal transport. Breakthrough curves for transport of two PFAS and one hydrocarbon surfactant in sand obtained from prior miscible-displacement experiments exhibited nonideal transport. The multiprocess model effectively simulated the measured transport data. The results of the analyses indicate that adsorption at the air-water and OIL-water interface can generally be treated as effectively instantaneous for transport in porous media. The rate limitations associated with solid-phase adsorption and diffusive mass transfer between advective and nonadvective domains were of greater significance.


Assuntos
Fluorcarbonetos , Adsorção , Porosidade , Dióxido de Silício , Água
8.
Water Res ; 168: 115192, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31654962

RESUMO

Ultraviolet filters (UVFs) are emerging organic compounds found in most water systems. They are constituents of personal care products, as well as industrial ones. The concentration of UVFs in the water bodies in space and time is mostly determined by degradation and sorption, both processes being determinant of their bioavailability and toxicity to ecosystems and humans. UVFs are a wide group of compounds, with different sorption behavior expected depending on the individual chemical properties (pKa,Koc,Kow). The goal of this work is framed in the context of improving our understanding of the sorption processes of UVFs occurring in the aquifer; that is, to evaluate the role of biomass growth, solid organic matter (SOM) and redox conditions in the characterization of sorption of a set of UVFs. We constructed a conceptual and a numerical model to evaluate the fate of selected UV filters, focused on both sorption and degradation. The models were validated with published data by Liu et al. (2013), consisting in a suite of batch experiments evaluating the fate of a cocktail of UVs under different redox conditions. The compounds evaluated included ionic UV filters (Benzophenone-3; 2-(3-t-butyl-2-hydroxy-5-methylphenyl)5-chloro-benzotriazole; 2-(2'-hydroxy-5'-octylphenyl)-benzotriazole) and neutral ones (octyl 4-methoxycinnamatte; and octocrylene).


Assuntos
Poluentes Químicos da Água , Biomassa , Ecossistema , Protetores Solares , Água
9.
Water Res ; 168: 115204, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31669779

RESUMO

Effect-directed analysis (EDA) has shown its added value for the detection and identification of compounds with varying toxicological properties in water quality research. However, for routine toxicity assessment of multiple toxicological endpoints, current EDA is considered labor intensive and time consuming. To achieve faster EDA and identification, a high-throughput (HT) EDA platform, coupling a downscaled luminescent Ames and cell-based reporter gene assays with a high-resolution fraction collector and UPLC-QTOF MS, was developed. The applicability of the HT-EDA platform in the analysis of aquatic samples was demonstrated by analysis of extracts from WWTP influent, effluent and surface water. Downscaled assays allowed detection of mutagenicity and androgen, estrogen and glucocorticoid agonism following high-resolution fractionation in 228 fractions. From 8 masses tentatively identified through non-target analysis, 2 masses were further investigated and chemically and biologically confirmed as the mutagen 1,2,3-benzotriazole and the androgen androstenedione. The compatibility of the high-throughput EDA platform with analysis of water samples and the incorporation of mutagenic and endocrine disruption endpoints allow for future application in routine monitoring in drinking water quality control and improved identification of (emerging) mutagens and endocrine disruptors.


Assuntos
Disruptores Endócrinos , Poluentes Químicos da Água , Monitoramento Ambiental , Mutagênicos , Águas Residuárias , Água
10.
Am J Dent ; 32(5): 229-234, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31675190

RESUMO

PURPOSE: To evaluate the influence of ceramic laminate on color stability, surface microhardness, water sorption, and solubility of resin luting agents. METHODS: Disk-shaped specimens (10 × 2 mm) of dual-cured resin cements (RelyX ARC or RelyX Ultimate) were obtained, and a light-cured luting agent (RelyX Veneer) was used. In Experiment 1, disk-shaped resin cements (n = 10) were submitted to: I) polymerization with or without ceramic laminate (0.7 mm), and II) immersion in distilled water or coffee, 3 hours daily for 20 days. The surface microhardness loss (%SML) was determined, and the color variables were assessed by the CIE L*a*b* system (ΔE, ΔL*) and the shade guide units (ΔSGU). In Experiment 2, other disk-shaped specimens (n = 5) were submitted to polymerization with or without ceramic laminate to assess their water sorption (WS) and solubility (S). Statistical analysis was performed using 3-way ANOVA and Tukey's test for ΔE, ΔL* and %SML; Mann-Whitney, Kruskal-Wallis, and Dunn's tests for ΔSGU; and 2-way ANOVA and Tukey's test for WS and S. The significance level was set at 5%. RESULTS: No statistically significant differences among the resin cements was observed for %SML, WS, or S, regardless of stain exposure or presence of ceramic laminate during light activation. Coffee caused a significant decrease in ΔL* values. All the resin cements presented visually detectable color alteration for ΔE; however, RelyX Ultimate showed less color change after coffee exposure. RelyX ARC showed the greatest color change in water. RelyX Veneer presented the highest values of ΔSGU, compared with the other resin cements. The WS, S, and %SML of resin cements were not influenced by the staining solution or the presence of ceramic laminate during light activation; however, RelyX Ultimate resin cement presented the best color stability. CLINICAL SIGNIFICANCE: Resin cements can present color changes over time, affecting the long-term esthetic success of laminate ceramic restorations. RelyX Ultimate resin cement presented the best color stability, thus making it a suitable indication for cementing ceramic laminates.


Assuntos
Porcelana Dentária , Cimentos de Resina , Cerâmica , Cor , Teste de Materiais , Solubilidade , Água
11.
Bioresour Technol ; 294: 122184, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31683452

RESUMO

To explore the feasibility of scaling up hydrothermal liquefaction (HTL) of algal biomass, a pilot-scale continuous flow reactor (CFR) was operated to produce bio-crude oil from algal biomass cultivated in urban wastewater. The CFR system ran algal slurry (5 wt.% solids loading) at 350 °C and 17 MPa for 4 h without any clogging issues. Bio-crude oil chemistry was characterized by high-resolution Fourier transform mass spectroscopy (FT-MS), proton nuclear magnetic resonance spectroscopy (1H NMR), bomb calorimetry, and elemental analysis. Bio-crude oil yield of 28.1 wt% was obtained with higher heating values of 38-39 MJ/kg. The quality of light bio-crude oil produced from the CFR system was comparable in terms of molecular structures to bio-crude oil produced in a batch reactor.


Assuntos
Microalgas , Petróleo , Biocombustíveis , Biomassa , Cromatografia Gasosa-Espectrometria de Massas , Temperatura Ambiente , Águas Residuárias , Água
12.
J Environ Qual ; 48(4): 1074-1081, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31589666

RESUMO

Concentrations of in bottom sediments can influence the assessment of microbial stream water quality. Runoff events bring nutrients to streams that can support the growth of in sediments. The objective of this work was to evaluate depth-dependent changes in populations after nutrients are introduced to the water column. Bovine feces were collected fresh and mixed into sediment. Studies were performed in a microcosm system with continuous flow of synthetic stream water over inoculated sediment. Dilutions of autoclaved bovine manure were added to water on Day 16 at two concentrations, and KBr tracer was introduced into the water column to evaluate ion diffusion. Concentrations of , total coliforms, and total aerobic heterotrophic bacteria, along with orthophosphate-P and ammonium N, were monitored in water and sediment for 32 d. Sediment samples were analyzed in 0- to 1-cm and 1- to 3-cm sectioned depths. Concentrations of and total coliforms in top sediments were approximately one order of magnitude greater than in bottom sediments throughout the experiment. Introduction of nutrients to the water column triggered an increase of nutrient levels in both top and bottom sediments and increased concentrations of bacteria in the water. However, the added nutrients had a limited effect on in sediment where bacterial inactivation continued. Vertical gradients of concentrations in sediments persisted during the inactivation periods both before and after nutrient addition to the water column.


Assuntos
Sedimentos Geológicos , Água , Animais , Bactérias , Bovinos , Fezes , Nutrientes
13.
J Environ Qual ; 48(4): 1016-1028, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31589678

RESUMO

Effective management of dairy manure is important to minimize N losses from cropping systems, maximize profitability, and enhance environmental sustainability. The objectives of this study were (i) to calibrate and validate the DeNitrification-DeComposition (DNDC) model using measurements of silage corn ( L.) biomass, N uptake, soil temperature, tile drain flow, NO leaching, NO emissions, and soil mineral N in eastern Canada, and (ii) to investigate the long-term impacts of manure management under climate variability. The treatments investigated included a zero-fertilizer control, inorganic fertilizer, and dairy manure amendments (raw and digested). The DNDC model overall demonstrated statistically "good" performance when simulating silage corn yield and N uptake based on normalized RMSE (nRMSE) < 10%, index of agreement () > 0.9, and Nash-Sutcliffe efficiency (NSE) > 0.5. In addition, DNDC, with its inclusion of a tile drainage mechanism, demonstrated "good" predictions for cumulative drainage (nRMSE < 20%, > 0.8, and NSE > 0.5). The model did, however, underestimate daily drainage flux during spring thaw for both organic and inorganic amendments. This was attributed to an underestimation of soil temperature and soil water under frequent soil freezing and thawing during the 2013-2014 overwinter period. Long-term simulations under climate variability indicated that spring applied manure resulted in less NO leaching and NO emissions than fall application when manure rates were managed based on crop N requirements. Overall, this study helped highlight the challenges in discerning the short-term climate interactions on fertilizer-induced N losses compared with the long-term dynamics under climate variability.


Assuntos
Fertilizantes , Zea mays , Agricultura , Canadá , Esterco , Nitrogênio , Silagem , Solo , Água
14.
J Environ Qual ; 48(5): 1127-1132, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31589703

RESUMO

After its discovery in 1669, phosphorus (P) was named ("the miraculous bearer of light"), arising from the chemoluminescence when white P is exposed to the atmosphere. The metaphoric association between P and light resonates through history: from the discovery of P at the start of the Enlightenment period to the vital role of P in photosynthetic capture of light in crop and food production through to new technologies, which seek to capitalize on the interactions between novel ultrathin P allotropes and light, including photocatalysis, solar energy production, and storage. In this introduction to the special section "Celebrating the 350th Anniversary of Discovering Phosphorus-For Better or Worse," which brings together 22 paper contributions, we shine a spotlight on the historical and emerging challenges and opportunities in research and understanding of the agricultural, environmental, and societal significance of this vital element. We highlight the role of P in water quality impairment and the variable successes of P mitigation measures. We reflect on the need to improve P use efficiency and on the kaleidoscope of challenges facing efficient use of P. We discuss the requirement to focus on place-based solutions for developing effective and lasting P management. Finally, we consider how cross-disciplinary collaborations in P stewardship offer a guiding light for the future, and we explore the glimmers of hope for reconnecting our broken P cycle and the bright new horizons needed to ensure future food, water, and bioresource security for growing global populations.


Assuntos
Mirabilis , Fósforo , Agricultura , Água
15.
J Environ Qual ; 48(5): 1380-1396, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31589740

RESUMO

Since its discovery in 1669, phosphorus (P) in the form of fertilizer has become an essential input for many agroecosystems. By introducing a concentrated P source, fertilizers increase short-term P export potential soon after their application and longer-term export potential by increasing soil fertility (legacy P). The 4R concept was developed to help mitigate P exports from the fertilizers that sustain agricultural productivity. This review investigates the factors affecting P exports soon after the application of mineral fertilizers to pasture-based grazing systems and studies quantifying its potential impact in different systems, with an emphasis on Australasia. Initially, P fertilizers and reactions that might affect their short-term P export potential are reviewed, along with P transport pathways, the forms of P exported from grazing systems, factors affecting P mobilization into water, and studies demonstrating the possible short-term effects of fertilizer application on P exports. Using that foundation, we review studies quantifying the short-term impact of fertilizer application in different regions; they show that under poor management, recently applied fertilizer can contribute a considerable proportion (30-80%) of total farm P exports in drainage, but when fertilizer is well-managed, that figure is expected to be <10%. We then use three model systems of varying hydrology that are common to Australasia to demonstrate the principles for selecting fertilizers that are likely to minimize P exports soon after their application.


Assuntos
Fertilizantes , Fósforo , Agricultura , Solo , Água
16.
J Appl Oral Sci ; 27: e20180663, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31596368

RESUMO

OBJECTIVE: To investigate the use of polymethyl methacrylate (PMMA) electrospun fiber mats containing different amounts of polyethylene oxide (PEO) as a doxycycline delivery system and to test antibacterial activity against an oral pathogen. METHODOLOGY: PMMA powders or PEO (mol wt 200 Kd) (10,20,30% w/w/) were dissolved in N, N-dimethylformamide (DMF) to obtain a final polymer concentration of 15% in DMF (w/v). 2% Doxycycline monohydrate was added to the solutions and submitted to vortex mixing. The solution was transferred to a plastic syringe and fit into a nanofiber electrospinning unit. The parameters applied were: voltage at 17.2 kV; distance of 20 cm between the needle tip and the collector plate; target speed at 2 m/min; and transverse speed at 1cm/min. Syringe pump speed was 0.15 mm/min. The drug release analysis was performed by removing aliquots of the drug-containing solution (in PBS) at specific periods. Doxycycline release was quantified using RP-HPLC. Fiber mats from all groups had their antibacterial action tested against S. mutans based on inhibition halos formed around the specimens. The experiments were performed in triplicate. Gravimetric analysis at specific periods was performed to determine any polymer loss. Morphological characterization of the electrospun fibers was completed under an optical microscope followed by SEM analysis. RESULTS: The addition of PEO to the PMMA fibers did not affect the appearance and diameter of fibers. However, increasing the %PEO caused higher doxycycline release in the first 24 h. Fibers containing 30% PEO showed statistically significant higher release when compared with the other groups. Doxycycline released from the fibers containing 20% or 30% of PEO showed effective against S. mutans. CONCLUSION: The incorporation of PEO at 20% and 30% into PMMA fiber mat resulted in effective drug release systems, with detected antibacterial activity against S. mutans.


Assuntos
Antibacterianos/farmacocinética , Doxiciclina/farmacocinética , Nanofibras/química , Polietilenoglicóis/farmacocinética , Polimetil Metacrilato/farmacocinética , Análise de Variância , Antibacterianos/química , Cromatografia Líquida de Alta Pressão/métodos , Doxiciclina/química , Imersão , Microscopia Eletrônica de Varredura , Peso Molecular , Polietilenoglicóis/química , Polimetil Metacrilato/química , Reprodutibilidade dos Testes , Streptococcus mutans/efeitos dos fármacos , Fatores de Tempo , Água/química
17.
J Environ Manage ; 252: 109611, 2019 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-31586748

RESUMO

In this study, the ZnO nanoparticles were doped with Ag and then hybridized on graphite (GP) layer (Ag-ZnO/GP) by a hydrothermal method, which was used as photocatalysts to remove metronidazole (MNZ) antibiotic from aqueous solutions. The fine structure, morphologies, and optical properties of the synthesized composites were first examined. The incorporation of Ag would readily reduce the rate of the recombination of electron-hole pairs and enhance the photocatalytic activity in a wide range of light wavelength. The graphite surface also acted as an electron sink to efficiently inhibit the photocorrosion of ZnO, thereby improving the photostability of the composites. The composition of the composite was optimized to be 0.5 wt% GP/ZnO and 1.0 wt% Ag/ZnO according to the extent of the enhancement of photocatalytic activity. In a solution containing 30 mg L-1 of MNZ and 0.5 g L-1 of Ag-ZnO/GP composite, it was shown that 88.5% and 97.3% of MNZ was removed after 60 min of 100-W UV and 180-min solar irradiation, respectively. Moreover, six over a total of eleven transformation products formed during UV photocatalysis were ascribed to the roles of reactive holes (h+), all which were detected and identified by high-resolution liquid chromatography-mass spectrometry (LC-MS). Finally, the pathways of MNZ degradation over Ag-ZnO/GP composite were proposed.


Assuntos
Grafite , Nanopartículas , Óxido de Zinco , Antibacterianos , Catálise , Metronidazol , Prata , Água
18.
Mymensingh Med J ; 28(4): 872-880, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31599254

RESUMO

V. cholerae and V. parahaemolyticus are responsible for majority of the Vibrio-related infections world wide. In this observational study, we selected three important river and pondsites of Dhaka city, Bangladesh to observe the presence of pathogenic V. cholerae, and V. parahaemolyticus. Surface water samples were collected from July 2013 to April 2014. Identification of V. cholerae was confirmed by the presence of ompW gene by PCR. Vibrio cholerae was found in the unique dual peak (March to May and September to November) patternin Mirpur-1 Mazar pond and Abdullahpur bridge river site, like many other studies reported earlier in Dhaka with only one exception of finding V. cholerae in the month of July 2013 in Mirpur-1 Mazar pond. A single peak was found from September to November in Mirpur-1 river sites. The ctxB positive non- O1 V. cholerae has also been reported. The presence of ctxB gene was observed by MAMA PCR. The O1 and O139 serogroups were confirmed by O1rfb and O139 rfb genes in PCR. Both classical and El-Tor biotypes were observed in this one year round study. V. paraheamolyticus was confirmed by the presence of ToxRVP gene and all the strains were negative for tdh pathogenic gene by PCR. This study observed for the first time the seasonal pattern of V. parahaemolyticus in water bodies in Bangladesh showing a peak from February to April in all three sampling sites and another additional peak which span from August to September in Mirpur-1 Mazar pond, Dhaka, Bangladesh.


Assuntos
Cólera/epidemiologia , Vibrio cholerae , Bangladesh/epidemiologia , Humanos , Estações do Ano , Água
19.
Chem Commun (Camb) ; 55(86): 12928-12931, 2019 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-31599273

RESUMO

Herein we report for the first time the site-selective C-H bond arylation of tryptophan and tryptophan residues in proteins in aqueous media at room temperature by using a PdNP bionanohybrid as a heterogeneous catalyst. The reaction proceeds using a stable aryldiazonium salt without a base.


Assuntos
Nanopartículas Metálicas/química , Paládio/química , Proteínas/química , Triptofano/química , Carbono/química , Catálise , Hidrogênio/química , Temperatura Ambiente , Água/química
20.
Top Curr Chem (Cham) ; 377(6): 29, 2019 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-31605243

RESUMO

Sustainable and high performance energy devices such as solar cells, fuel cells, metal-air batteries, as well as alternative energy conversion and storage systems have been considered as promising technologies to meet the ever-growing demands for clean energy. Hydrogen evolution reaction (HER) is a crucial process for cost-effective hydrogen production; however, functional electrocatalysts are potentially desirable to expedite reaction kinetics and supply high energy density. Thus, the development of inexpensive and catalytically active electrocatalysts is one of the most significant and challenging issues in the field of electrochemical energy storage and conversion. Realizing that advanced nanomaterials could engender many advantageous chemical and physical properties over a wide scale, tremendous efforts have been devoted to the preparation of earth-abundant transition metals as electrocatalysts for HER in both acidic and alkaline environments because of their low processing costs, reasonable catalytic activities, and chemical stability. Among all transition metal-based catalysts, nickel compounds are the most widely investigated, and have exhibited pioneering performances in various electrochemical reactions. Heterostructured nickel phosphide (NixPy) based compounds were introduced as promising candidates of a new category, which often display chemical and electronic characteristics that are distinct from those of non-precious metals counterparts, hence providing an opportunity to construct new catalysts with an improved activity and stability. As a result, the library of NixPy catalysts has been enriched very rapidly, with the possibility of fine-tuning their surface adsorption properties through synergistic coupling with nearby elements or dopants as the basis of future practical implementation. The current review distils recent advancements in NixPy compounds/hybrids and their application for HER, with a robust emphasis on breakthroughs in composition refinement. Future perspectives for modulating the HER activity of NixPy compounds/hybrids, and the challenges that need to be overcome before their practical use in sustainable hydrogen production are also discussed.


Assuntos
Hidrogênio/química , Níquel/química , Água/química , Catálise , Complexos de Coordenação/síntese química , Complexos de Coordenação/química , Técnicas Eletroquímicas , Nanoestruturas/química , Elementos de Transição/química
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