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1.
Chemosphere ; 241: 125120, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31683447

RESUMO

FeCl3 is a valuable iron salt used in the synthesis of magnetic waste cotton woven-based activated carbon. Although it has received extensive research attention, more information is required regarding its interactions with the carbon matrix. This systematic study describes the potential reactions of FeCl3 and waste cotton woven. First, the textural properties of waste cotton woven-based activated carbon synthesized under various conditions were investigated via element analysis, N2 sorption/desorption isotherms, and scanning electron microscopy. Then, the possible reaction mechanisms were deduced through various characterization methods. The results demonstrate that FeCl3 can lower the initial decomposition temperature of WCW to 135 °C and catalyze decarboxylation and decarbonylation at 100-330 °C to elevate the formation of microporous structures. Moreover, FeCl3 can also form Lewis acid sites at 330-700 °C and promote the cross-linking reaction to develop intricate microporous structures and carbonaceous materials with the synergistic effect of Fe3+ and Cl-. FeCl3 could be used as a template-like agent to form mesoporous structures. Meanwhile, it can also act as a magnetizer that Fe3O4 derived from the decomposition of FeCl3 would insert into the carbon matrix and combine with C-Cl to tailor the magnetic controllable activated carbon. Finally, we confirmed that extending the activation time could convert the structure of waste cotton woven-based activated carbon and increase the number of active sites, thereby further improving the catalytic properties of FeCl3 in pore formation.


Assuntos
Carbono/química , Cloretos/química , Compostos Férricos/química , Fenômenos Magnéticos , Têxteis , Adsorção , Fibra de Algodão , Microscopia Eletrônica de Varredura , Porosidade , Temperatura Ambiente
2.
Chemistry ; 26(4): 888-899, 2020 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-31696989

RESUMO

The anion-binding and transport properties of an extensive library of thiophene-based molecules are reported. Seventeen bis-urea positional isomers, with different binding conformations and lipophilicities, have been synthesized by appending α- or ß-thiophene or α-, ß-, or γ-benzo[b]thiophene moieties to an ortho-phenylenediamine central core, yielding six subsets of positional isomers. Through 1 H NMR, X-ray crystallography, molecular modelling, and anion efflux studies, it is demonstrated that the most active transporters adopt a pre-organized binding conformation capable of promoting the recognition of chloride, using urea and C-H binding groups in a cooperative fashion. Additional large unilamellar vesicle-based assays, carried out under electroneutral and electrogenic conditions, together with N-methyl-d-glucamine chloride assays, have indicated that anion efflux occurs mainly through an H+ /Cl- symport mechanism. On the other hand, the most efficient anion transporter displays cytotoxicity against tumor cell lines, while having no effects on a cystic fibrosis cell line.


Assuntos
Ânions/química , Cloretos/química , Tiofenos/química , Ureia/química , Transporte Biológico , Linhagem Celular Tumoral , Cristalografia por Raios X , Humanos , Transporte de Íons , Espectroscopia de Ressonância Magnética
3.
Chemosphere ; 241: 124985, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31606001

RESUMO

Municipal solid waste incineration (MSWI) bottom ash is an environmentally harmful solid waste that cannot be recycled without pre-treatment. The chloride content in bottom ash (BA) is a major obstacle that restricts its application as secondary building materials. Here, the chemical speciation of the chlorides in BA is systematically studied with multiple analytical techniques, i.e., quantitative XRD, microanalysis and XPS. In addition to halite (NaCl), several chloride-rich minerals are present in BA. These phases are hydrous metal oxides, ettringite, decomposed hydration products (C4A3) and incineration slag with a chloride content of 3.2%, 1.4%, 2.1% and 1.3%, respectively. For the first time, the real-time leaching profiles of chloride (up to 80 h) from BA were obtained with a chloride-ion specific electrode to explain the leaching mechanism. In the initial stage of leaching, highly soluble alkali salts (NaCl) and physisorbed chlorides (especially those adsorbed on hydrous metal oxides) are released, which is controlled by diffusion. Later, the leaching is controlled by the solubility/reactivity of the chloride-containing phases, such as ettringite and incineration slag. The results show that the release of chloride is not only a diffusion-controlled process, as reported in the literature, but also a reaction-controlled phenomenon, during which the chloride-rich phases decompose and release chlorides that are associated with them via sorption/incorporation.


Assuntos
Cloretos/análise , Cinza de Carvão/química , Incineração , Resíduos Sólidos , Adsorção , Cloretos/química , Cidades , Materiais de Construção , Reciclagem , Sais , Resíduos Sólidos/análise
4.
Chemosphere ; 241: 124971, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31590024

RESUMO

Organophosphate triesters (OPEs) have caused great concern as a class of emerging environmental contaminants due to their widespread use and their toxicity to organisms. However, the phototransformation behavior of OPE is still not fully understood, which is important for understanding their environmental fate. In the present study, the photodegradation of tricresyl phosphate (TCP), one of the most widely detected OPEs in aqueous environments, was investigated including the direct photolysis and in the presence of several natural water factors, NO2-, Fe3+ and humic acid. The degradation process followed the pseudo-first-order kinetics, with rate constant increasing slightly with increasing initial TCP concentration. The presence of NO2- and Fe3+ was observed to promote the photochemical loss of TCP, while humic acid played a negative role on TCP transformation. Electron spin resonance (EPR) analysis showed that carbon-centered radical was produced in the photolysis process of TCP, and hydroxyl radical contributed to the promotion of rate constant for Fe3+ and NO2-. Four photolysis products were tentatively identified by HPLC-LTQ-Orbitrap MS analysis, and the possible degradation pathways of TCP were proposed. These findings provide a meaningful reference for the fate and transformation of OPEs in natural water.


Assuntos
Fotólise , Tritolil Fosfatos/química , Poluentes Químicos da Água/química , Cloretos/química , Compostos Férricos/química , Substâncias Húmicas/análise , Radical Hidroxila/análise , Cinética , Nitrito de Sódio/química , Tritolil Fosfatos/análise , Tritolil Fosfatos/efeitos da radiação , Água/química , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/efeitos da radiação
5.
Sci Total Environ ; 702: 134887, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31726343

RESUMO

In contrast to some salts such as chlorides (Cl) that enhance cadmium (Cd) phyto-uptake, complex soil organics like humates (HA) potentially minimise Cd uptake, but are depleted in soils low in organic matter. Organically-depleted and salt-affected areas frequently coincide in (semi)arid agroecosystems where inappropriate management practices may load topsoils with Cd. We evaluated the impact of HA (0-100 mg/kg) and NaCl (0-60 mM) in Cd-contaminated (0-5 mg/kg) soil on the chemical changes in the rhizosphere and Cd uptake by two radish (Raphanus sativus L.) cultivars. In the rhizosphere solution the significant HAxCd interaction resulted in a decrease in Cd concentration with increasing HA rates, whereas the NaClxCd interaction was brought about by an increase in Cd concentration with NaCl rising. Also, the NaClxCd interaction increased Cd concentration in radish hypocotyl with increasing NaCl addition; in contrast, the HAxCd interaction reduced Cd concentration in hypocotyl, notably at the highest Cd rate, with increasing soil humification. The addition of HA acted as a biostimulant in both radish cultivars and decreased Cd accumulation (up to 44%), whereas NaCl stress reduced the root growth and enhanced total Cd accumulation (by almost 50%). Dose-dependent severity of Cd toxicity was confirmed in both cultivars by reduced growth and progressive (up to 2 orders of magnitude) Cd accumulation (vs. uncontaminated soil). Ion speciation modelling suggested that chemistry of deprotonated humates and chlorides is crucial for complexation of the most bioavailable Cd2+ species, thus driving Cd mobility within the soil matrix, including uptake by plants. Detected differences between the tested cultivars (e.g. lower Cd concentration in Sparkler vs. Cherry Belle) and their impacts on rhizosphere chemistry and Cd soil-plant acquisition/root-hypocotyl-shoot (re)distribution, suggest that genetic improvements (by developing and introducing salt- and/or metal-resistant varieties) should be exploited in phytoremediation of contaminated soils or for minimising metal accumulation in sustainable food production.


Assuntos
Cádmio/metabolismo , Substâncias Húmicas , Raphanus/metabolismo , Poluentes do Solo/metabolismo , Biodegradação Ambiental , Cádmio/química , Cloretos/química , Rizosfera , Solo , Poluentes do Solo/química
6.
Chemosphere ; 239: 124769, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31526997

RESUMO

In this study, Cerium chloride-induced conformational changes of Bovine Liver Catalase (BLC) has been investigated by molecular docking and further supported by various biophysical techniques. The temporal change of catalytic activity of BLC has also been studied in presence of Ce(III) with different buffer solution in vitro at 25 °C. The differential binding of Ce(III) to BLC observed by simulation study was well supported by the differential regulation of BLC activity in different buffers. After 1 h of incubation with CeCl3, the reduction in activity of BLC was maximum in MOPS, HEPES and Tris buffer, whereas no change in activity was noticed in phosphate buffer. Isothermal Titration Calorimetric (ITC) study also supports the differential binding of Ce(III) to BLC in different buffers. Ce(III)-induced conformational transition in BLC was followed as a function of concentration. Nevertheless, with 24 h incubation of CeCl3 the activity of BLC was highest with higher molar concentration of CeCl3 suggesting the conformational stability of BLC in presence of Ce(III). The compromised activity of BLC in response to Ce(III) is due to the induced conformational change and the degree of change in secondary conformation of BLC was maximum in MOPS, HEPES and Tris and least in phosphate buffer. Therefore, the reduced activity of BLC is controlled by the direct interaction of Ce(III) in the active site of BLC in Tris buffer or indirect interaction of Ce(III) in the non-active site of BLC in MOPS and HEPES buffer.


Assuntos
Catalase/química , Catalase/metabolismo , Cério/química , Fígado/enzimologia , Animais , Tampões (Química) , Calorimetria , Domínio Catalítico , Bovinos , Cério/metabolismo , Cloretos/química , Simulação de Acoplamento Molecular , Conformação Proteica
7.
Chemosphere ; 238: 124675, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31524615

RESUMO

A synergistic combination of chloride and copper powder was proposed as a new method to reductively remove arsenic from highly-acidic wastewater with high arsenic content (HAWA). As(III) was reduced to As(0) by copper powder in the presence of chloride and were effectively removed from HAWA. The procedure to remove arsenic was optimized as follows: initial H+ concentration of 5 mol L-1, Cu-to-As molar ratio of 8, Cl-to-As molar ratio of 10, a reaction temperature of 60 °C, copper powder particle size of 68-24 µm, and a stirring speed of 300 r min-1. Under these optimal conditions, the removal rate of arsenic was close to 100%. Kinetics results suggested that the arsenic removal process was controlled by both diffusion and chemical reactions with an apparent activation energy of 29.78 kJ mol-1. The XRD results showed that the removed arsenic in the residue existed primarily in the form of AsCu3 alloy.


Assuntos
Arsênico/análise , Águas Residuárias/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Cloretos/química , Cloro , Cobre/química , Concentração de Íons de Hidrogênio
8.
J Photochem Photobiol B ; 200: 111646, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31655457

RESUMO

Antimicrobial Photodynamic Therapy (aPDT) is an alternative to conventional treatments of local infections such as the use of antibiotics, which may lead to the development of resistance. aPDT besides requiring the use of a photosensitiser also needs a light source do be carried out. In the search for efficient and low-cost procedure the use of multispectral polarized light (λ400-2000 nm) emerges as a possibility for the execution of aPDT. The use of a highly effective photosensitizer is also of great importance. 1,9-Dimethyl-Methylene Blue Zinc Chloride Double Salt - DMMB is a potent phenothiazine derivative that presents high photodynamic action due to its high lipophilicity as well as a greater quantum yield of Singlet oxygen and phototoxicity when compared to other Photosensitizers. The aim of this study was to assess, In Vitro, the efficacy of aPDT on Staphylococcus aureus (ATCC 25923) using different concentrations of DMMB associated to a Polarized light source (Bioptron®, 40 mW, ᴓ = 15.8 cm2) using different energy densities. Based on the IC50, 150 and 300 ng/mL of DMMB concentrations were chosen for this study. Twelve experimental groups were used: (Control, PLs, PSs and aPDTs). Serial dilutions (up to 10-8) of the bacterial inoculum were used and the DMMB was added using the two previously determined concentrations. After 5 min of preincubation the dilutions of the inoculum were illuminated by the polarized light source. Subsequently, 100 µL of each dilution, in triplicate, were inoculated into Petri dishes containing TSA medium and incubated in a bacteriological oven at 37 °C for 24-h and quantification of UFCs was done. The results showed significant exponential reduction (p < .0001) of 99.93% (150 ng/mL + LP 10 J/cm2) and 99.97% (300 ng/mL + LP 5 J/cm2) the CFU counts in comparison to non-illuminated control. The results of this study allow to conclude that aPDT carried out with 1,9-Dimethyl-Methylene Blue Zinc Chloride Double Salt-DMMB and a PL souce was efficacious on the reduction (99.97%), in vitro, of the bacterial counts of S. aureus.


Assuntos
Anti-Infecciosos/farmacologia , Cloretos/química , Azul de Metileno/análogos & derivados , Fármacos Fotossensibilizantes/química , Staphylococcus aureus/efeitos dos fármacos , Compostos de Zinco/química , Anti-Infecciosos/química , Luz , Azul de Metileno/química , Fotoquimioterapia , Fármacos Fotossensibilizantes/farmacologia
9.
Molecules ; 24(20)2019 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-31614959

RESUMO

It was recently shown that tetramethylammonium chloride presented negative deviations to ideality when mixed with tetraethylammonium chloride or tetrapropylammonium chloride, leading to a strong decrease of the melting points of these salt mixtures, in a behavior akin to that observed in the formation of deep eutectic solvents. To better rationalize this unexpected melting point depression between two structurally similar compounds devoid of dominant hydrogen bonding capability, new solid-liquid equilibria data for tetramethylammonium-based systems were measured and analyzed in this work. Molecular dynamics was used to show that the strong negative deviations from ideality presented by these systems arise from a synergetic share of the chloride ions. A transfer of chloride ions seems to occur from the bigger cation in the mixture (which possesses a more disperse charge) to the smaller cation (tetramethylammonium), resembling the formation of metal-chloride complexes in type I deep eutectic solvents. This rearrangement of the charged species leads to an energetic stabilization of both components in the mixture, inducing the negative deviations to the ideality observed. The conclusions presented herein emphasize the often-neglected contribution of charge delocalization in deep eutectic solvents formation and its applicability toward the design of new ionic liquid mixtures.


Assuntos
Complexos de Coordenação/química , Líquidos Iônicos/química , Solventes/química , Cátions/química , Cloretos/química , Ligações de Hidrogênio , Simulação de Dinâmica Molecular , Estrutura Molecular , Compostos de Amônio Quaternário/química , Ureia/química
10.
Pharmacol Rev ; 71(4): 571-595, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31551350

RESUMO

Endogenous ions play important roles in the function and pharmacology of G-protein coupled receptors (GPCRs). Historically the evidence for ionic modulation of GPCR function dates to 1973 with studies of opioid receptors, where it was demonstrated that physiologic concentrations of sodium allosterically attenuated agonist binding. This Na+-selective effect was distinct from effects of other monovalent and divalent cations, with the latter usually counteracting sodium's negative allosteric modulation of binding. Since then, numerous studies documenting the effects of mono- and divalent ions on GPCR function have been published. While ions can act selectively and nonselectively at many sites in different receptors, the discovery of the conserved sodium ion site in class A GPCR structures in 2012 revealed the unique nature of Na+ site, which has emerged as a near-universal site for allosteric modulation of class A GPCR structure and function. In this review, we synthesize and highlight recent advances in the functional, biophysical, and structural characterization of ions bound to GPCRs. Taken together, these findings provide a molecular understanding of the unique roles of Na+ and other ions as GPCR allosteric modulators. We will also discuss how this knowledge can be applied to the redesign of receptors and ligand probes for desired functional and pharmacological profiles. SIGNIFICANCE STATEMENT: The function and pharmacology of GPCRs strongly depend on the presence of mono and divalent ions in experimental assays and in living organisms. Recent insights into the molecular mechanism of this ion-dependent allosterism from structural, biophysical, biochemical, and computational studies provide quantitative understandings of the pharmacological effects of drugs in vitro and in vivo and open new avenues for the rational design of chemical probes and drug candidates with improved properties.


Assuntos
Receptores Acoplados a Proteínas-G/antagonistas & inibidores , Receptores Acoplados a Proteínas-G/metabolismo , Sódio/metabolismo , Sítio Alostérico , Ânions/química , Ânions/metabolismo , Sítios de Ligação , Cátions Bivalentes/química , Cátions Bivalentes/metabolismo , Cátions Monovalentes/química , Cátions Monovalentes/metabolismo , Cloretos/química , Cloretos/metabolismo , Cristalografia por Raios X , Humanos , Ligantes , Conformação Proteica , Receptores Acoplados a Proteínas-G/química , Sódio/química , Relação Estrutura-Atividade , Zinco/química , Zinco/metabolismo
11.
Chemosphere ; 235: 1015-1021, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31561290

RESUMO

Phosphate is one of the main contaminations in water, so an effective method of decreasing or removing phosphate is needed. The main purpose of this paper is to synthesize CaFe-LDHs and MgFe-LDHs from the mixture of calcined dolomite and ferric chloride to remove orthophosphate and pyrophosphate. The study showed that removal of orthophosphate was attributed to the precipitation by Ca2+ and adsorption by MgFe-LDHs, where the former played a main role. As for pyrophosphate, it was mainly removed by precipitation at the initial pyrophosphate concentration ranging from 3.228 to 17.04 mmol/L. When the initial concentrations became relatively higher, the removal efficiency of pyrophosphate decreased because the complexation effects by Fe3+, Ca2+ and Mg2+ took place.


Assuntos
Carbonato de Cálcio/química , Cloretos/química , Difosfatos/análise , Compostos Férricos/química , Hidróxidos/química , Magnésio/química , Fosfatos/análise , Poluentes Químicos da Água/análise , Difosfatos/isolamento & purificação , Fosfatos/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos
12.
Environ Int ; 132: 105128, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31479958

RESUMO

The roles of chloride in enhanced oxidative degradation of refractory organic pollutants are recently identified in the Cu(II)/H2O2/Cl- system, but the identity of the reactive oxidants and potential conversion of inorganic chloride to organochlorine in such oxidizing environment remain obscure. Here we report that Cu(II)/H2O2/Cl- system is a unique "halotolerant" Fenton-like process that works most efficiently in saline water among the five tested redox-active metals ions (i.e. Cr(VI), Ce(III), Co(II), Mn(II) and Cu(II)). The observed pseudo first-order rate constant for 2,4,6-trichlorophenol (TCP) degradation was linearly correlated with the elevated Cl- content. The TCP degradation rate at [Cl-]0 = 1000 mM by the Cu(II)/H2O2 system was approximately 46-fold higher than that at [Cl-]0 = 5 mM. The optimal mineralization rate of TCP and percentage of absorbable organic halogens (AOX) decrease were 31.6% and 63.8%, respectively, in the tested Cu(II)/H2O2/Cl- system. However, the detection of fused chlorinated byproducts (i.e. chloro-anthracene-pentaol, dioxine, chlorinated dibenzofuran) reminds us of cautiousness in evaluating the applicability of Cu(II)-catalyzed Fenton-like reaction, particularly while it is to be applied to the treatment of wastewater contaminated with chlorophenols. Two independent models (i.e. "Cu(III) model" and "OH model") were developed to describe the kinetics of Cu(II)/H2O2/Cl- system. The failure of "OH model" to rationalize the observed AOX decay has disproved the "OH model" through reductio ad absurdum. The ability of "Cu(III) model" to adequately explain the experimental data demonstrates that Cu(III)-chloro complexes, rather than OH, is the major product resulting from reactions between Cu(I)-chloro complexes and H2O2 at neutral pH.


Assuntos
Cloretos/química , Clorofenóis/química , Cobre/química , Peróxido de Hidrogênio/química , Poluentes Químicos da Água/química , Catálise , Concentração de Íons de Hidrogênio , Cinética , Oxirredução , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química
13.
J Agric Food Chem ; 67(41): 11489-11497, 2019 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-31560530

RESUMO

The design of gelatin-based hydrogels with high mechanical strength, high gelation temperature, and a rapid self-healing property still presents a challenge to researchers. In the present study, single cross-linked gelatin-oxidized tannic acid (SC-GT/OTA) hydrogels were fabricated through covalent cross-linking between gelatin and tannic acid (TA) oxidized by using sodium periodate (NaIO4). Double cross-linked gelatin-OTA-FeCl3·6H2O (DC-GT/OTA/FeIII) hydrogels were also created using metal coordination bonds formed between the catechol groups present in OTA and FeIII in ferric chloride. As a result, the maximum gelling temperature of the SC-GT/OTA hydrogel (37 °C) was considerably higher than that of the pure gelatin hydrogel (15.4 °C). Moreover, the maximum values of compressive stress of SC-GT/OTA hydrogels increased significantly by almost seven times the original value as the molar ratio of NaIO4 to TA increased from 3:1 to 5:1. When the molar ratio of NaIO4 to TA was maintained at the constant of 4:1, the storage modulus values of DC-GT/OTA/FeIII hydrogels with the FeIII-to-TA molar ratio of 1.5:1 were three to 4 orders of magnitude higher than those of SC-GT/OTA hydrogels in the whole angular frequency range. The double cross-linked gelatin hydrogels developed in this research can be used widely in agriculture and material science fields.


Assuntos
Cloretos/química , Compostos Férricos/química , Gelatina/química , Hidrogéis/química , Taninos/química , Fenômenos Biomecânicos , Reagentes para Ligações Cruzadas/química , Oxirredução , Temperatura Ambiente
14.
Anal Chim Acta ; 1080: 138-145, 2019 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-31409463

RESUMO

The test of sweat chloride is routinely performed as a worldwide newborn screening (NBS) to the diagnosis of cystic fibrosis (CF) in infants. However, the available methods for measurement of chloride in sweat suffer from such limitations as either low selectivity and/or requiring relatively large sample size. In this work, we have designed an analytical ruler that can measure chloride ion in sweat and hence can be used for the diagnosis of cystic fibrosis. This micro-pad (µ-PAD) device is fabricated by making hydrophilic micro-channel on a filter paper impregnated with silver dichromate. After addition of chloride ion-containing sweat sample, it moves through the channel, leading to the formation of an AgCl sediment, which deposits as a white color stain, the length of which in the channel being proportional to the amount of chloride ion in sweat. A well-defined linear relation was observed between the length of white color stain and the concentration of chloride ion in the sample solutions with a relative standard deviation of 3.6% (n = 3) for an artificial sweat sample containing 100 mM chloride ion. The possible interfering effects of several different cations and anions on the detection of chloride ion were investigated and the results well-confirmed the selectivity of the proposed method. With the use of only 2.0 µL of the sample solution, the µPAD was able to measure the chloride content of sweat over a concentration range of 20.0-100.0 mM, which covers both the healthy range (˂ 40 mM) and the risky range (˃60 mM) of chloride ion. Analysis of chloride content of sweat samples by the µPAD agreed well with those obtained by a standard electrochemical method (with relative errors of lower than 10%).


Assuntos
Calorimetria/métodos , Cloretos/análise , Fibrose Cística/diagnóstico , Papel , Suor/química , Calorimetria/instrumentação , Cloretos/química , Cromatos/química , Humanos , Recém-Nascido , Limite de Detecção , Compostos de Potássio/química , Nitrato de Prata/química
15.
J Appl Oral Sci ; 27: e20180453, 2019 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-31411261

RESUMO

OBJECTIVE: This study was designed for the chemical activation of a 35% hydrogen peroxide (H2O2) bleaching gel to increase its whitening effectiveness and reduce its toxicity. METHODOLOGY: First, the bleaching gel - associated or not with ferrous sulfate (FS), manganese chloride (MC), peroxidase (PR), or catalase (CT) - was applied (3x 15 min) to enamel/dentin discs adapted to artificial pulp chambers. Then, odontoblast-like MDPC-23 cells were exposed for 1 h to the extracts (culture medium + components released from the product), for the assessment of viability (MTT assay) and oxidative stress (H2DCFDA). Residual H2O2 and bleaching effectiveness (DE) were also evaluated. Data were analyzed with one-way ANOVA complemented with Tukey's test (n=8. p<0.05). RESULTS: All chemically activated groups minimized MDPC-23 oxidative stress generation; however, significantly higher cell viability was detected for MC, PR, and CT than for plain 35% H2O2 gel. Nevertheless, FS, MC, PR, and CT reduced the amount of residual H2O2 and increased bleaching effectiveness. CONCLUSION: Chemical activation of 35% H2O2 gel with MC, PR, and CT minimized residual H2O2 and pulp cell toxicity; but PR duplicated the whitening potential of the bleaching gel after a single 45-minute session.


Assuntos
Peróxido de Hidrogênio/química , Peróxido de Hidrogênio/toxicidade , Clareadores Dentários/química , Clareadores Dentários/toxicidade , Clareamento Dental/métodos , Análise de Variância , Catalase/química , Sobrevivência Celular , Células Cultivadas , Cloretos/química , Cor , Polpa Dentária/química , Polpa Dentária/diagnóstico por imagem , Dentina/química , Dentina/efeitos dos fármacos , Compostos Ferrosos/química , Compostos de Manganês/química , Odontoblastos/efeitos dos fármacos , Peroxidase/química , Valores de Referência , Reprodutibilidade dos Testes , Estatísticas não Paramétricas , Fatores de Tempo
16.
Environ Sci Pollut Res Int ; 26(29): 30365-30373, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31435909

RESUMO

Environmental benefits of biochar require a simple and effective method for preparation of functional N-doped biochar. In this study, urea/ZnCl2 was developed to prepare N-doped biochar via in situ hydrothermal carbonization (HTC) of Camellia sinensis waste at 120-280 °C for 2 h under 1.0-9.8 MPa. Physicochemical and structural properties of the N-doped biochar were investigated by Raman spectra, elemental analysis, BET surface area, SEM, TEM, XRD, and XPS. The results showed that the N content in biochar could reach up to 7.79% at 280 °C. Surface chemistry suggested that pyridinic N, pyrollic N, and graphitic N were the major N species on the biochar. Moreover, the N-doped biochar was successfully employed to remove metal ions Cu2+, Pb2+, Zn2+, and Cr6+. Adsorption data fit closely to the pseudo-second-order kinetic equation and the Langmuir adsorption isotherm model for all metal ions.


Assuntos
Camellia sinensis/química , Carvão Vegetal/química , Metais Pesados/isolamento & purificação , Ureia/química , Adsorção , Carbono/química , Cloretos/química , Cinética , Microscopia Eletrônica de Varredura , Nitrogênio/química , Espectroscopia Fotoeletrônica , Análise Espectral Raman , Resíduos , Poluentes Químicos da Água/isolamento & purificação , Difração de Raios X , Compostos de Zinco/química
17.
Environ Sci Pollut Res Int ; 26(27): 28361-28371, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31372953

RESUMO

Aging effects play a crucial role in determining applications of green-synthesised iron-based nanoparticles in wastewater treatment from laboratory scale to practical applications. In this study, iron-based nanoparticles (Ec-Fe-NPs) were synthesised using the extract of Eichhornia crassipes and ferric chloride. Scanning electron microscopy (SEM) revealed that the fresh Ec-Fe-NPs were spherical and had a narrow particle size range (50 to 80 nm). X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) demonstrated that the Ec-Fe-NPs were mainly amorphous in nature and consisted of Fe0, FeO, Fe2O3 and Fe3O4. As they aged, the particle size of the liquid Ec-Fe-NPs gradually increased and then tended to stabilise. Ec-Fe-NPs that were aged for 28 days were only 19% less efficient than fresh material at removing Cr(VI). Extracts aged up to 28 days were also tested, and their antioxidant capacity was found to be 15.4% lower than that of the fresh extracts. Furthermore, the removal efficiency of Cr(VI) using iron-based nanoparticles synthesised with the aged extracts was 67.2%. Finally, the active components of the extracts, which were responsible for the reactivity and stability of the iron-based nanoparticles, were identified by liquid chromatography-mass spectrometry. Overall, green-synthesised iron-based nanoparticles show promise for Cr(VI) removal from wastewater in practical applications.


Assuntos
Cloretos/química , Eichhornia/química , Compostos Férricos/química , Compostos de Ferro/síntese química , Nanopartículas Metálicas/química , Extratos Vegetais/química , Águas Residuárias/análise , Compostos de Ferro/química , Microscopia Eletrônica de Varredura , Tamanho da Partícula , Espectroscopia Fotoeletrônica , Difração de Raios X
18.
Water Sci Technol ; 79(11): 2046-2055, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31318342

RESUMO

The purpose of this study was to optimize the coagulation-flocculation effect of a wastewater treatment system using the response surface methodology (RSM) and three-step method to minimize phosphorus concentration in the distillate wastewater. In order to minimize the concentration of total phosphorus (TP), experiments were carried out using 33-factorial designs with three levels and three factors. A Box-Behnken design, which is the standard design of RSM, was used to evaluate the effects and interactions of three major factors (Fe:P (w/w) ratio, coagulation pH and fast mixing speed (FMS)) on the treatment efficiency. A multivariable quadratic model developed for studying the response indicated that the values for optimum conditions for Fe:P (w/w) ratio, coagulation pH and FMS were 2.40, 6.48 and 100 rev min-1, respectively. Under optimal process conditions, the TP concentration in the distillery effluent was reduced from 10 mg L-1 to 0.215 mg L-1, representing a removal efficiency of 97.85%. Based upon the statistical evaluation of results, it is inferred that RSM can be used as an appropriate approach to optimize the coag-flocculation process. Meanwhile, the study has shown that, for the equivalent dose of ferric chloride, the average three-step effect is better than that of the one-time addition.


Assuntos
Fósforo/análise , Eliminação de Resíduos Líquidos/métodos , Cloretos/química , Compostos Férricos/química , Floculação , Fósforo/química
19.
Nanoscale ; 11(30): 14426-14433, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31334729

RESUMO

Nanopore DNA sequencing with a solid-state nanopore requires deceleration of the ultrafast translocation speed of single-stranded DNA (ssDNA). We report an unexpected phenomenon: controlled dielectric breakdown (CBD) with a divalent metal cation, especially Ca2+, provides a silicon nitride nanopore with the ability to decelerate ssDNA speed to 100 µs per base even after solution replacement. This speed is two orders of magnitude slower than that for CBD with a conventional monovalent metal cation. Temperature dependence experiments revealed that the enthalpic barrier for a nanopore created via CBD with Ca2+ is 25-30kBT, comparable to that of a biological nanopore. The slowing effect originates from the strong interaction between ssDNA and divalent cations, which were coated on the sidewall of the nanopore during the CBD process. In addition, we found that the nanopore created via CBD with Ca2+ can decelerate the speed of even single-nucleotide monomers, dNMPs, to 0.1-10 ms per base. The four single nucleotides could be statistically identified according to their blockade currents. Our approach is simple and practical because it simultaneously allows nanopore fabrication, ssDNA deceleration and the identification of nucleotide monomers.


Assuntos
Nanoporos , Compostos de Silício/química , Cátions Bivalentes/química , Césio/química , Cloretos/química , DNA de Cadeia Simples/química , DNA de Cadeia Simples/metabolismo , Nucleotídeos/análise , Análise de Sequência de DNA/métodos , Temperatura Ambiente
20.
J Pharm Biomed Anal ; 174: 639-643, 2019 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-31279893

RESUMO

Heparin is a carbohydrate polymer, which is clinically used as an anticoagulant for the treatment of thrombotic disorders. The anticoagulant process is mainly mediated by the interaction of heparin with antithrombin followed by inhibition of clotting factors IIa (FIIa) and Xa (FXa). The influence of polymer disaccharide structure, average molecular weight and impurity profiling (e.g., chloride and water content) was investigated by NMR spectrometry and principal component analysis (PCA) for a representative dataset of porcine heparin samples (n = 509). A significant linear dependence was found between anticoagulant activity and scores on the third principal component (PC3) based on the non-targeted analysis of 1H NMR fingerprints. The correlation between average molecular values and anticoagulant activity for the 24 porcine heparin samples from two manufacturers was linear (R = 0.85) over typical values for porcine heparin preparations. Chloride and water contents were identified as negatively influencing factors for the actual activity values as their presence decrease the "pharmaceutically active" organic part of heparin preparations. Some suggestions regarding manufacturing process are made according to the results.


Assuntos
Anticoagulantes/análise , Heparina/análise , Espectroscopia de Ressonância Magnética , Animais , Anticoagulantes/química , Cloretos/química , Dissacarídeos/química , Fator Xa/química , Inibidores do Fator Xa/análise , Inibidores do Fator Xa/química , Heparina/química , Heparina de Baixo Peso Molecular/análise , Modelos Lineares , Peso Molecular , Polímeros/química , Análise de Componente Principal , Protrombina/química , Suínos , Água/química
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