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1.
J Chem Phys ; 151(15): 154304, 2019 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-31640364

RESUMO

The dynamics of iodide-uracil-water (I-·U·H2O) clusters following π-π* excitation of the nucleobase are probed using time-resolved photoelectron spectroscopy. Photoexcitation of this cluster at 4.77 eV results in electron transfer from the iodide moiety to the uracil, creating a valence-bound anion within the cross correlation of the pump and probe laser pulses. This species can decay by a number of channels, including autodetachment and dissociation to I- or larger anion fragments. Comparison of the energetics of the photoexcited cluster and its decay dynamics with those of the bare iodide-uracil (I-·U) complex provides a sensitive probe of the effects of microhydration on these species.


Assuntos
Iodetos/química , Uracila/química , Água/química , Elétrons , Iodetos/efeitos da radiação , Oxirredução , Espectroscopia Fotoeletrônica , Raios Ultravioleta , Uracila/efeitos da radiação
2.
Anal Chim Acta ; 1083: 150-156, 2019 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-31493805

RESUMO

Most of the on-site approaches for inferring of the post-mortem interval are still based on observative data from the direct body inspection, whereas, objective and quantitative analyses, such as potassium in the vitreous humor, are require laboratory instrumentation and skilled personnel. The present paper presents a simple and low cost analytical method suitable for use at the crime scene for inferring the time since death. The method uses a microfluidic paper-based device (µPAD) for the determination of ammonium in the vitreous humor (VH) based on the selective interaction between the ammonium and the Nessler's reagent. The color change was measured in terms of "RGB distance" by using a simple and free smartphone application. The optimized device showed a limit of detection of 0.4 mmol L-1, with between days precision less than 9.3% expressed as relative standard deviation, and accuracy between days from 94.5% to 104.5%. The selectivity of the Nessler's reaction was tested towards the main vitreous humor compounds, and no significant interferences were found. This paper-based analytical device was successfully used for the determination of ammonium ion in VH samples from forensic autopsies. The results obtained with the proposed method, although for a limited number of cases (n = 25), showed a close correlation with the data obtained with an instrumental analysis based on capillary electrophoresis. Moreover, in order to make the evaluation of results as simple as possible, a direct correlation between the color intensity, expressed as RGB distance, and the post-mortem interval was studied and a significant correlation was found (R2 > 0.78). In conclusion, the present preliminary study showes that the proposed device could be an additional tool to the traditional methods for a more accurate, although still presumptive, estimation of the time of death directly at the crime scene.


Assuntos
Compostos de Amônio/análise , Medicina Legal/métodos , Papel , Mudanças Depois da Morte , Corpo Vítreo/química , Adulto , Idoso , Colorimetria/instrumentação , Colorimetria/métodos , Medicina Legal/instrumentação , Humanos , Iodetos/química , Limite de Detecção , Compostos de Mercúrio/química , Técnicas Analíticas Microfluídicas/instrumentação , Técnicas Analíticas Microfluídicas/métodos , Pessoa de Meia-Idade , Estudo de Prova de Conceito , Reprodutibilidade dos Testes , Fatores de Tempo , Adulto Jovem
3.
J Phys Chem Lett ; 10(18): 5343-5350, 2019 Sep 19.
Artigo em Inglês | MEDLINE | ID: mdl-31452370

RESUMO

In this work, a sensitive deep ultraviolet (DUV) light photodetector based on inorganic and lead-free Cs3Cu2I5 crystalline film derived by a solution method was reported. Optoelectronic characterization revealed that the perovskite device exhibited nearly no sensitivity to visible illumination with wavelength of 405 nm but exhibited pronounced sensitivity to both DUV and UV light illumination with response speeds of 26.2/49.9 ms for rise/fall time. The Ilight/Idark ratio could reach 127. What is more, the responsivity and specific detectivity were calculated to be 64.9 mA W-1 and 6.9 × 1011 Jones, respectively. In addition, the device could keep its photoresponsivity after storage in air environment for a month. It is also found that the capability of Cs3Cu2I5 crystalline film device can readily record still DUV image with acceptable resolution. The above results confirm that the DUV photodetector may hold great potential for future DUV optoelectronic device and systems.


Assuntos
Compostos de Cálcio/química , Césio/química , Cobre/química , Desenho de Equipamento/instrumentação , Iodetos/química , Óxidos/química , Titânio/química , Cristalização , Técnicas Eletroquímicas/métodos , Cinética , Membranas Artificiais , Processos Fotoquímicos , Fenômenos Físicos , Propriedades de Superfície , Termodinâmica , Raios Ultravioleta
4.
Molecules ; 24(15)2019 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-31366075

RESUMO

The aim of this study was to estimate the mode of thyroid peroxidase (TPO) inhibition by polyphenols: Chlorogenic acid, rosmarinic acid, quercetin, and rutin. All the tested polyphenols inhibited TPO; the IC50 values ranged from 0.004 mM to 1.44 mM (for rosmarinic acid and rutin, respectively). All these pure phytochemical substances exhibited different modes of TPO inhibition. Rutin and rosmarinic acid showed competitive, quercetin-uncompetitive and chlorogenic acid-noncompetitive inhibition effect on TPO. Homology modeling was used to gain insight into the 3D structure of TPO and molecular docking was applied to study the interactions of the inhibitors with their target at the molecular level. Moreover, the type and strength of mutual interactions between the inhibitors (expressed as the combination index, CI) were analyzed. Slight synergism, antagonism, and moderate antagonism were found in the case of the combined addition of the pure polyphenols. Rutin and quercetin as well as rutin and rosmarinic acid acted additively (CI = 0.096 and 1.06, respectively), while rutin and chlorogenic acid demonstrated slight synergism (CI = 0.88) and rosmarinic acid with quercetin and rosmarinic acid with chlorogenic acid showed moderate antagonism (CI = 1.45 and 1.25, respectively). The mixture of chlorogenic acid and quercetin demonstrated antagonism (CI = 1.79). All the polyphenols showed in vitro antiradical ability against 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid), ABTS. The highest ability (expressed as IC50) was exhibited by rosmarinic acid (0.12 mM) and the lowest value was ascribed to quercetin (0.45 mM).


Assuntos
Ácido Clorogênico/química , Cinamatos/química , Depsídeos/química , Iodeto Peroxidase/química , Iodetos/química , Quercetina/química , Rutina/química , Motivos de Aminoácidos , Animais , Antioxidantes/química , Benzotiazóis/antagonistas & inibidores , Domínio Catalítico , Inibidores Enzimáticos/química , Expressão Gênica , Iodeto Peroxidase/antagonistas & inibidores , Iodeto Peroxidase/isolamento & purificação , Iodeto Peroxidase/metabolismo , Iodetos/metabolismo , Cinética , Simulação de Acoplamento Molecular , Ligação Proteica , Conformação Proteica em alfa-Hélice , Conformação Proteica em Folha beta , Domínios e Motivos de Interação entre Proteínas , Homologia de Sequência de Aminoácidos , Especificidade por Substrato , Ácidos Sulfônicos/antagonistas & inibidores , Suínos , Termodinâmica , Glândula Tireoide/química , Glândula Tireoide/enzimologia
5.
Nat Commun ; 10(1): 3555, 2019 08 07.
Artigo em Inglês | MEDLINE | ID: mdl-31391472

RESUMO

Poly-substituted aromatic sulfur compounds are widely found in pharmaceuticals, agrochemicals and organic materials. However, the position that a sulfur moiety can be introduced to is largely restricted to a pre-functionalized site; otherwise, use of electronically biased substrates or auxiliary groups that direct catalysis is required. Here we report a general ortho thiolation of common aryl and heteroaryl iodides via palladium-norbornene cooperative catalysis. Using this approach, an aryl or alky sulfur moiety can be site-selectively introduced at the arene ortho position without using sterically or electronically biased substrates. The arene ipso functionalization is simultaneously achieved through Heck, Suzuki or Sonogashira termination. The reaction is enabled by a unique class of electrophiles in palladium-norbornene cooperative catalysis, which are sulfenamides derived from seven-membered lactams. The broad substrates scope and high chemoselectivity could make this method attractive for synthesis of complex sulfur-containing aromatic compounds.


Assuntos
Técnicas de Química Sintética/métodos , Iodetos/química , Compostos de Sulfidrila/síntese química , Amidas/química , Catálise , Norbornanos/química , Paládio/química , Enxofre/química
6.
Molecules ; 24(14)2019 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-31331092

RESUMO

Hypervalent iodine reagents are of considerable relevance in organic chemistry as they can provide a complementary reaction strategy to the use of traditional transition metal chemistry. Over the past two decades, there have been an increasing number of applications including stoichiometric oxidation and catalytic asymmetric variations. This review outlines the main advances in the past 10 years in regard to alkene heterofunctionalization chemistry using achiral and chiral hypervalent iodine reagents and catalysts.


Assuntos
Alcenos/química , Iodetos/química , Catálise , Oxirredução
7.
Pan Afr Med J ; 32: 174, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31303943

RESUMO

Introduction: Precancerous cervical lesion is significantly a health problem globally. Thus, screening targeting women between the ages of 17-60 is being undertaken in developing countries, including Cameroon. Over 50% (7.8 per 100,000) women die of cervical cancer every year. This study was to determine the prevalence of precancerous cervical lesion, the age demography and access the risk factor. Methods: A hospital-based cross-sectional study was conducted from August 09th to October 17th 2017. A total of 60 women participated, and were screened for precancerous cervical lesion. Data were collected by using a questionnaire. Visual inspection with acetic acid and visual inspection with Lugol's iodine was applied for the screening. SPSS version 16.0 was used for data entry and analysis. Logistic regression analysis was fitted and odds ratios with 95% confidence intervals and p-values were computed to identify factors associated with precancerous cervical cancer lesion. Results: Out of 60 study participants, 2(3.33%) were found to be positive for precancerous cervical cancer lesion. Conclusion: The prevalence of precancerous cervical lesion in women that consulted at the Mezam polyclinic is high.


Assuntos
Colo do Útero/patologia , Programas de Rastreamento/métodos , Lesões Pré-Cancerosas/epidemiologia , Neoplasias do Colo do Útero/diagnóstico , Ácido Acético/química , Adolescente , Adulto , Camarões/epidemiologia , Estudos Transversais , Feminino , Humanos , Iodetos/química , Modelos Logísticos , Pessoa de Meia-Idade , Lesões Pré-Cancerosas/diagnóstico , Prevalência , Fatores de Risco , Inquéritos e Questionários , Neoplasias do Colo do Útero/epidemiologia , Adulto Jovem
8.
ACS Appl Mater Interfaces ; 11(30): 27279-27287, 2019 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-31265242

RESUMO

This work introduces a piezoelectric-pyroelectric nanogenerator (P-PNG) based on methylammonium lead iodide (CH3NH3PbI3) incorporated electrospun poly(vinylidene fluoride) (PVDF) nanofibers that are able to harvest mechanical and thermal energies. During the application of a periodic compressive contact force at a frequency of 4 Hz, an output voltage of ∼220 mV is generated. The P-PNG has a piezoelectric coefficient (d33) of ∼19.7 pC/N coupled with a high durability (60 000 cycles) and quick response time (∼1 ms). The maximum generated output power density (∼0.8 mW/m2) is sufficient to charge up a variety of capacitors, with the potential to replace an external power supply to drive portable devices. In addition, upon exposure to cyclic heating and cooling at a temperature of 38 K, a pyroelectric output current of 18.2 pA and a voltage of 41.78 mV were achieved. The fast response time of 1.14 s, reset time of 1.25 s, and pyroelectric coefficient of ∼44 pC/m2 K demonstrate a self-powered temperature sensing capability of the P-PNG. These characteristics make the P-PNG suitable for flexible piezoelectric-pyroelectric energy harvesting for self-powered electronic devices.


Assuntos
Fontes de Energia Elétrica , Metilaminas/química , Nanofibras/química , Iodetos/química , Chumbo/química , Transição de Fase , Polivinil/química
9.
Environ Sci Pollut Res Int ; 26(23): 23850-23860, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31214887

RESUMO

The environmental fate of iodine is of general geochemical interest as well as of substantial concern in the context of nuclear waste repositories and reprocessing plants. Soils, and in particular soil organic matter (SOM), are known to play a major role in retaining and storing iodine. Therefore, we investigated iodide and iodate sorption by four different reference soils for contact times up to 30 days. Selective sequential extractions and X-ray absorption spectroscopy (XAS) were used to characterize binding behavior to different soil components, and the oxidation state and local structure of iodine. For iodide, sorption was fast with 73 to 96% being sorbed within the first 24 h, whereas iodate sorption increased from 11-41% to 62-85% after 30 days. The organic fraction contained most of the adsorbed iodide and iodate. XAS revealed a rapid change of iodide into organically bound iodine when exposed to soil, while iodate did not change its speciation. Migration behavior of both iodine species has to be considered as iodide appears to be the less mobile species due to fast binding to SOM, but with the potential risk of mobilization when oxidized to iodate.


Assuntos
Iodatos/química , Iodo/química , Solo/química , Adsorção , Iodetos/química , Oxirredução , Espectroscopia por Absorção de Raios X
10.
Talanta ; 200: 511-517, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31036217

RESUMO

Microfluidic paper-based analytical devices (µPADs) for detection of hydrogen peroxide and glucose have been developed. The analytical performance of colorimetric detection using the conventional starch-iodine color reaction has been significantly improved by using gelatin as the surface modifier which retains the enzyme activity in the dry filter paper strip, improves antioxidability, as well as decreases the strong background signal. Under optimal conditions, the color intensities show a good linear relationship with glucose concentration ranging from 0.5 to 5 mM and hydrogen peroxide concentration from 0.5 to 6 mM, with the detection limit of 0.05 mM and 0.1 mM, respectively. In addition, the accuracy of colorimetric sensor has been successfully assessed in detecting glucose from real human serum samples and recovery value ranges from 95.7% to 97%, which are approaching to the glucose oxidase endpoint. The new colorimetric assay exhibits high sensitivity, good selectivity, acceptable stability and reproducibility. The present approach is promising for monitoring glucose for point of care diagnostic applications, especially in regions with resource-limited settings.


Assuntos
Colorimetria , Gelatina/química , Glucose/análise , Peróxido de Hidrogênio/análise , Iodetos/química , Técnicas Analíticas Microfluídicas , Papel , Amido/química , Humanos
11.
J Phys Chem Lett ; 10(11): 3013-3018, 2019 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-31091107

RESUMO

Direct, label-free sequence analysis of DNA hybridization has been achieved by surface-enhanced Raman spectroscopy. In this work, aluminum-ion-aggregated and iodide-modified silver nanoparticles were used as substrates to obtain Raman spectra of the DNA strands with the same base composition but different sequences, which form random coils or various hairpin conformations. Upon DNA hybridization, reproducibly enhanced bands were easily observed, corresponding well to the formation of Watson-Crick hydrogen bonds, base ring breathing vibrations, and hairpin loops. These characteristic bands can be used to unambiguously distinguish the hairpins from the random DNA conformation. Moreover, by using the deoxyribose band (959 cm-1) as an internal standard to normalize the characteristic bands at 1703 cm-1 corresponding to the dG νC=O H bond, the guanine-cytosine base-pair contents and sequence in DNA hairpins can be accurately measured. Applying this method, a single base mutation in a functional double helix was confidently identified.


Assuntos
DNA/química , Alumínio/química , Composição de Bases , Pareamento Incorreto de Bases , Pareamento de Bases , Sequência de Bases , Citosina/química , Guanina/química , Ligações de Hidrogênio , Iodetos/química , Nanopartículas Metálicas/química , Tamanho da Partícula , Prata/química , Análise Espectral Raman , Propriedades de Superfície
12.
Molecules ; 24(10)2019 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-31137910

RESUMO

In inverted perovskite solar cells (PSCs), high-quality perovskite film grown on hole-transporting material (HTM) with pinhole-free coverage and a large grain size is crucial for high efficiency. Here, we report on the growth of pinhole-free and large grain CH3NH3PbI3 crystals favored by a hydrophobic small molecular HTM, namely, 4,4'-Bis(4-(di-p-toyl)aminostyryl)biphenyl (TPASBP). The hydrophobic surface induced by TPASBP suppressed the density of the perovskite nuclei and heterogeneous nucleation, thus promoting the perovskite to grow into a dense and homogeneous film with a large grain size. The CH3NH3PbI3 deposited on the TPASBP exhibited better crystallization and a lower trap density than that on the hydrophilic surface of indium tin oxide (ITO), resulting in a significant reduction in carrier recombination. Combined with the efficient hole extraction ability of TPASBP, a high efficiency of 18.72% in the inverted PSCs fabricated on TPASBP was achieved.


Assuntos
Compostos de Cálcio/química , Iodetos/química , Chumbo/química , Metilaminas/química , Óxidos/química , Energia Solar , Titânio/química , Cristalização , Eletricidade , Interações Hidrofóbicas e Hidrofílicas , Espectrofotometria Ultravioleta , Compostos de Estanho/química , Difração de Raios X
13.
Phys Chem Chem Phys ; 21(14): 7239-7255, 2019 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-30855623

RESUMO

Iodide-nucleobase (I-·N) clusters studied by time-resolved photoelectron spectroscopy (TRPES) are an opportune model system for examining radiative damage of DNA induced by low-energy electrons. By initiating charge transfer from iodide to the nucleobase and following the dynamics of the resulting transient negative ions (TNIs) with femtosecond time resolution, TRPES provides a novel window into the chemistry triggered by the attachment of low-energy electrons to nucleobases. In this Perspective, we examine and compare the dynamics of electron attachment, autodetachment, and photodissociation in a variety of I-·N clusters, including iodide-uracil (I-·U), iodide-thymine (I-·T), iodide-uracil-water (I-·U·H2O), and iodide-adenine (I-·A), to develop a more unified representation of our understanding of nucleobase TNIs. The experiments probe whether dipole-bound or valence-bound TNIs are formed initially and the subsequent time evolution of these species. We also provide an outlook for forthcoming applications of TRPES to larger iodide-containing complexes to enable the further investigation of microhydration dynamics in nucleobases, as well as electron attachment and photodissociation in more complex nucleic acid constituents.


Assuntos
Adenina/química , Citosina/química , Iodetos/química , Timina/química , Uracila/química , Elétrons , Lasers , Espectroscopia Fotoeletrônica , Fotólise , Teoria Quântica
14.
J Antibiot (Tokyo) ; 72(6): 449-460, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30886347

RESUMO

Steryl glycosides are prevalent in nature and have unique biological activities dictated by sterol structure, sugar composition, and the stereochemical attachment of the aglycone. A single configurational switch can have profound biological consequences meriting the systematic study of structure and function relationships. Steryl congeners of N-acetyl neuraminic acid (NANA) impact neurobiological processes and may also mediate host/microbe interactions. In order to study these processes, a platform for the synthesis of ß-steryl sialosides has been established. Promoter-free glycosidations using a novel α-linked sialyl iodide donor efficiently provide unique amphiphilic sialoglycoconjugates for examining bioactivities in various systems.


Assuntos
Iodetos/síntese química , Ácidos Siálicos/química , Glicosídeos/química , Iodetos/química , Estrutura Molecular , Esteróis/química
15.
Environ Int ; 126: 576-584, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30852445

RESUMO

Silver-impregnated zeolite (AgIZ) has been used for removing radioiodine from contaminated groundwater and nuclear waste streams and the worldwide inventory of such secondary waste is rapidly increasing. The objective of this study was to 1) quantify the effectiveness of two grout waste forms for disposing of the used AgIZ, and 2) determine the I speciation leached from AgIZ encapsulated in grout. A 60-day kinetics batch experiment demonstrated that AgIZ encapsulated in slag-free grout was extremely effective at immobilizing I and Ag, a potential non-radioactive carcinogen. However, AgIZ encapsulated in slag-containing grout, the most common type of grout used for low-level radioactive waste disposal, was entirely ineffective at immobilizing I. While the slag-free grout with AgIZ released only 3.3 µg/L Itotal into the contact solution, the slag-containing grout released 19,269 µg/L Itotal. Based on thermodynamic calculations, the strongly reducing conditions of the slag-containing system (Eh was -392 mV) promoted the reductive dissolution of the AgI, forming Ag0(aq) and releasing iodide (I-) into the aqueous phase. The slag-free grout system was maintained under more oxidizing conditions (Eh was 439 mV) and a minimal amount of I was released from the grout. In both grout systems, the aqueous I, originally added to the AgZ as iodide, was composed primarily of iodide and org-I, and essentially no iodate was detected. More organo-I was detected in the slag-free than the slag-containing grout system because the high redox potential of the former system was more conducive to the formation of oxidized I species, such as I2, which may be intermediates in the covalent bonding of I with organic C in grout. Iodine K-edge XANES analysis indicated that I existed exclusively as silver iodide in both AgIZ-grout samples. Together, these results indicate that subsurface grout disposal of AgIZ waste should be done under oxidizing conditions and that radioiodide released from AgIZ can undergo speciation transformations that have important implications on subsequent mobility and estimated risk.


Assuntos
Iodetos/química , Radioisótopos do Iodo/química , Poluentes Radioativos/química , Resíduos Radioativos , Compostos de Prata/química , Zeolitas/química , Água Subterrânea/química , Iodo/química , Oxirredução , Gerenciamento de Resíduos/métodos
16.
Molecules ; 24(5)2019 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-30857232

RESUMO

Bisindolyl alkaloids represent a large family of natural and synthetic products that display various biological activities. Among the bisindole compounds, 6,7,12,13-tetrahydro-5H-cyclohepta[2,1-b:3,4-b']diindoles have received little attention. Only two methods have been developed for the construction of the 6,7,12,13-tetrahydro-5H-cyclohepta[2,1-b:3,4-b']diindole scaffold thus far, including the classical Fischer indole synthesis conducted by reacting indole-fused cycloheptanone and hydrazines, and the condensation reaction to build the seven-membered ring. Here, we report for the first time a new route to synthesize 6,7,12,13-tetrahydro-5H-cyclohepta[2,1-b:3,4-b']diindoles through intramolecular oxidative coupling of 1,3-di(1H-indol-3-yl)propanes in the presence of PIFA, DDQ and TMSCl with moderate to excellent yields.


Assuntos
Indóis/química , Iodo/química , Indicadores e Reagentes/química , Iodetos/química , Iodobenzenos/química , Estrutura Molecular , Ácido Trifluoracético/química
17.
Environ Int ; 125: 172-183, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30716577

RESUMO

In this work, potassium iodide (KI) and graphene oxide (GO) were utilized to promote the selectivity of photocatalytic process for alkali lignin oxidation over ZnO. Different concertation of GO was added during the microwave synthesis procedure of ZnO, and the characterization results revealed that graphene can shift the conduction band to more reducing potential, resulting to higher production of superoxide anion radicals (O2-) compared to OH. Response Surface Methodology revealed the most suitable interaction among loading of GO, KI and irradiation time on lignin and total phenolic compound (TPC) degradation. Specifically, the optimal conditions (i.e. maximum lignin (52%) and minimum TPC (55%) degradation) were at [KI] = 0.64 mM; GO content into ZnO 1.2 mg/mL; 240 min of irradiation time. The results showed that higher addition of graphene into structure of ZnO could preserve more phenolics from degradation due to less production of OH. Furthermore, the addition of KI at optimized conditions could enhance the selectivity of degradation of lignin and phenolics via producing I radicals and quenching the excess amount of generated OH, respectively. The lower generation of OH at optimized conditions was quantitatively confirmed by a photoluminescence simplified technique. In addition, the effect of the photocatalytic process on substrate's anaerobic degradability was examined in order to evaluate the suitability of the pretreated solution for energy recovery. Indeed, besides the higher TPC concentration, the biogas production of treated straw at optimized conditions was increased by 35% compared to the untreated sample.


Assuntos
Grafite/química , Lignina/química , Nanopartículas Metálicas/química , Óxido de Zinco/química , Biocombustíveis , Catálise , Iodetos/química , Oxirredução , Raios Ultravioleta
18.
Environ Pollut ; 246: 717-727, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30616062

RESUMO

The antibacterial agent norfloxacin (NOR) and sodium hypochlorite (NaClO), which are both widely used in marine culture, react with each other to form the halogenated disinfection byproducts (X-DBPs). The effects of the water characteristics and iodide concentration on the reaction kinetics were investigated. The results showed that the reaction rate of NOR with NaClO increases from 0.0586 min-1 to 0.1075 min-1 when the iodide concentration was changed from 0 µg-1 to 50 µg-1. This demonstrated the enhancement of NOR oxidation in the presence of iodide ions. Four novel iodinated DBPs (I-DBPs) were identified in the marine culture water. Iodine substitutions occurred at the C3 and C8 positions of NOR. The formation mechanisms of X-DBPs in the marine culture water were proposed based on the intermediate and final products. NOR may undergo a ring-opening reaction, a de-carbonyl reaction and substitution to form intermediates and finally generate the X-DBPs. Furthermore, the predicted logKOW and logBCF values of the I-DBPs were higher than that of the Br-DBPs and Cl-DBPs. The AOX concentration in the synthetic water samples decreased in the following order: seawater (8.49 mg L-1) > marine culture water (4.05 mg L-1) > fresh water (1.89 mg L-1). The amount of AOX also increased with the increase in iodide concentration. These results indicated that the I-DBPs were more toxic than their brominated and chlorinated analogues.


Assuntos
Organismos Aquáticos/efeitos dos fármacos , Desinfetantes/química , Desinfecção/métodos , Iodetos/química , Norfloxacino/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Halogenação , Cinética , Oxirredução
19.
Anal Bioanal Chem ; 411(5): 997-1007, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30637437

RESUMO

A fluorescent sensing platform using KI3-quenched bovine serum albumin stabilized gold nanoclusters has been designed and used as a fluorescent probe for the turn-on detection of homocysteine/cysteine (Cys/Hcy). The fluorescence of gold nanoclusters was quenched by iodine. The fluorescence of quenched gold nanoclusters was effectively switched on by Cys/Hcy devoid of the interference of glutathione. The transmission electron microscopy image, X-ray photoelectron spectroscopy analysis, time-correlated single photon counting analysis, and dynamic light scattering data confirmed the aggregation-induced quenching of fluorescence of gold nanoclusters by iodine. The turn-on response of Cys/Hcy shows two linear ranges from 0.0057 to 5 µM and from 8 to 25 µM, with a limit of detection of 9 nM for cysteine and 12 nM for homocysteine. Real samples were analyzed to monitor Cys/Hcy added to human serum. The fluorescence turn-on response of the probe on a paper strip in the presence of Cys/Hcy was studied. Graphical abstract ᅟ.


Assuntos
Cisteína/sangue , Corantes Fluorescentes/química , Ouro/química , Homocisteína/sangue , Iodetos/química , Nanopartículas Metálicas/química , Humanos , Limite de Detecção , Nanopartículas Metálicas/ultraestrutura , Fitas Reagentes/análise , Espectrometria de Fluorescência/métodos
20.
Spectrochim Acta A Mol Biomol Spectrosc ; 207: 150-155, 2019 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-30223249

RESUMO

Hydrogen sulfide (H2S) can undergo dual nucleophilic reaction, which is a wise and effective way to distinguish biothiols and H2S. A novel H2S fluorescence probe, 4-{2-[4-(2-disulfide pyridyl-benzoyloxy)-phenyl]-vinyl}-1-methyl-pyridinium[e]iodide (DSPBP), with two nucleophilic reaction sites has been developed. The spectra results showed that DSPBP could detect H2S in ratiometric and colorimetric signals and has excellent selectivity and sensitivity. The fluorescence ratiometric signals (F520/F450) displayed a prominent increase from 0.74 to 7.08, the fluorescence color turned to yellow form blue simultaneously. The linear range was 2-14 µM and its detection limit was 25.7 nM. Moreover, the biocompatibility of DSPBP was fine and its toxicity was very low. It has been successfully used for imaging H2S in cells.


Assuntos
Dissulfetos/química , Corantes Fluorescentes/química , Sulfeto de Hidrogênio/análise , Iodetos/química , Células HeLa , Humanos , Microscopia de Fluorescência/métodos , Imagem Óptica/métodos , Espectrometria de Fluorescência/métodos , Água/análise , Poluentes Químicos da Água/análise
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