Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 37
Filtrar
1.
Environ Sci Technol ; 58(1): 432-439, 2024 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-38111081

RESUMO

Reactive oxygen species (ROS) are widespread in nature and play central roles in numerous biogeochemical processes and pollutant dynamics. Recent studies have revealed ROS productions triggered by electron transfer from naturally abundant reduced iron minerals to oxygen. Here, we report that ROS productions from pyrite oxidation exhibit a high facet dependence. Pyrites with various facet compositions displayed distinct efficiencies in producing superoxide (O2• -), hydrogen peroxide (H2O2), and hydroxyl radical (•OH). The 48 h •OH production rates varied by 3.1-fold from 11.7 ± 0.4 to 36.2 ± 0.6 nM h-1, showing a strong correlation with the ratio of the {210} facet. Such facet dependence in ROS productions primarily stems from the different surface electron-donating capacities (2.2-8.6 mmol e- g-1) and kinetics (from 1.2 × 10-4 to 5.8 × 10-4 s-1) of various faceted pyrites. Further, the Fenton-like activity also displayed 10.1-fold variations among faceted pyrites, contributing to the facet depedence of •OH productions. The facet dependence of ROS production can greatly affect ROS-driven pollutant transformations. As a paradigm, the degradation rates of carbamazepine, phenol, and bisphenol A varied by 3.5-5.3-fold from oxidation of pyrites with different facet compositions, where the kinetics were in good agreement with the pyrite {210} facet ratio. These findings highlight the crucial role of facet composition in determining ROS production and subsequent ROS-driven reactions during iron mineral oxidation.


Assuntos
Poluentes Ambientais , Peróxido de Hidrogênio , Espécies Reativas de Oxigênio/química , Espécies Reativas de Oxigênio/metabolismo , Peróxido de Hidrogênio/química , Peróxido de Hidrogênio/metabolismo , Ferro/química , Oxirredução , Oxigênio
2.
Environ Sci Technol ; 58(24): 10623-10631, 2024 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-38781516

RESUMO

Iron minerals are widespread in earth's surface water and soil. Recent studies have revealed that under sunlight irradiation, iron minerals are photoactive on producing reactive oxygen species (ROS), a group of key species in regulating elemental cycling, microbe inactivation, and pollutant degradation. In nature, iron minerals exhibit varying crystallinity under different hydrogeological conditions. While crystallinity is a known key parameter determining the overall activity of iron minerals, the impact of iron mineral crystallinity on photochemical ROS production remains unknown. Here, we assessed the photochemical ROS production from ferrihydrites with different degrees of crystallinity. All examined ferrihydrites demonstrated photoactivity under irradiation, resulting in the generation of hydrogen peroxide (H2O2) and hydroxyl radical (•OH). The photochemical ROS production from ferrihydrites increased with decreasing ferrihydrite crystallinity. The crystallinity-dependent photochemical •OH production was primarily attributed to conduction band reduction reactions, with the reduction of O2 by conduction band electrons being the rate-limiting key process. Conversely, the crystallinity of iron minerals had a negligible influence on photon-to-electron conversion efficiency or surface Fenton-like activity. The difference in ROS productions led to a discrepant degradation efficiency of organic pollutants on iron mineral surfaces. Our study provides valuable insights into the crystallinity-dependent ROS productions from iron minerals in natural systems, emphasizing the significance of iron mineral photochemistry in natural sites with abundant lower-crystallinity iron minerals such as wetland water and surface soils.


Assuntos
Ferro , Minerais , Espécies Reativas de Oxigênio , Ferro/química , Espécies Reativas de Oxigênio/química , Minerais/química , Radical Hidroxila/química , Peróxido de Hidrogênio/química
3.
Environ Sci Technol ; 58(6): 2808-2816, 2024 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-38227742

RESUMO

Hydroxyl radical (•OH) is a powerful oxidant abundantly found in nature and plays a central role in numerous environmental processes. On-site detection of •OH is highly desirable for real-time assessments of •OH-centered processes and yet is restrained by a lack of an analysis system suitable for field applications. Here, we report the development of a flow-injection chemiluminescence analysis (FIA-CL) system for the continuous field detection of •OH. The system is based on the reaction of •OH with phthalhydrazide to generate 5-hydroxy-2,3-dihydro-1,4-phthalazinedione, which emits chemiluminescence (CL) when oxidatively activated by H2O2 and Cu3+. The FIA-CL system was successfully validated using the Fenton reaction as a standard •OH source. Unlike traditional absorbance- or fluorescence-based methods, CL detection could minimize interference from an environmental medium (e.g., organic matter), therefore attaining highly sensitive •OH detection (limits of detection and quantification = 0.035 and 0.12 nM, respectively). The broad applications of FIA-CL were illustrated for on-site 24 h detection of •OH produced from photochemical processes in lake water and air, where the temporal variations on •OH productions (1.0-12.2 nM in water and 1.5-37.1 × 107 cm-3 in air) agreed well with sunlight photon flux. Further, the FIA-CL system enabled field 24 h field analysis of •OH productions from the oxidation of reduced substances triggered by tidal fluctuations in coastal soils. The superior analytical capability of the FIA-CL system opens new opportunities for monitoring •OH dynamics under field conditions.


Assuntos
Radical Hidroxila , Luminescência , Radical Hidroxila/análise , Radical Hidroxila/química , Peróxido de Hidrogênio , Oxirredução , Água
4.
Environ Sci Technol ; 57(2): 1177-1185, 2023 01 17.
Artigo em Inglês | MEDLINE | ID: mdl-36538289

RESUMO

Photochemically generated reactive oxygen species (ROS) play numerous key roles in earth's surface biogeochemical processes and pollutant dynamics. ROS production has historically been linked to the photosensitization of natural organic matter. Here, we report the photochemical ROS production from three naturally abundant iron minerals. All investigated iron minerals are photoactive toward sunlight irradiation, with photogenerated currents linearly correlated with incident light intensity. Hydroxyl radicals (•OH) and hydrogen peroxide (H2O2) are identified as the major ROS species, with apparent quantum yields ranging from 1.4 × 10-8 to 3.9 × 10-8 and 5.8 × 10-8 to 2.5 × 10-6, respectively. Photochemical ROS production exhibits high wavelength dependence, for instance, the •OH quantum yield decreases with the increase of light wavelength from 375 to 425 nm, and above 425 nm it sharply decreases to zero. The temperature shows a positive impact on •OH production, with apparent activation energies ranging from 8.0 to 17.8 kJ/mol. Interestingly, natural iron minerals with impurities exhibit higher ROS production than their pure crystal counterparts. Compared with organic photosensitizers, iron minerals exhibit higher wavelength dependence, higher selectivity, lower efficiency, and long-term stability in photochemical ROS production. Our study highlights natural inorganic iron mineral photochemistry as a ubiquitous yet previously overlooked source of ROS.


Assuntos
Ferro , Luz Solar , Espécies Reativas de Oxigênio , Peróxido de Hidrogênio/química , Minerais
5.
Environ Sci Technol ; 57(23): 8610-8616, 2023 06 13.
Artigo em Inglês | MEDLINE | ID: mdl-37226678

RESUMO

The hydroxyl radical (•OH) is a potent oxidant and key reactive species in mediating element cycles and pollutant dynamics in the natural environment. The natural source of •OH is historically linked to photochemical processes (e.g., photoactivation of natural organic matter or iron minerals) or redox chemical processes (e.g., reaction of microbe-excreted or reduced iron/natural organic matter/sulfide-released electrons with O2 in soils and sediments). This study revealed a ubiquitous source of •OH production via water vapor condensation on iron mineral surfaces. Distinct •OH productions (15-478 nM via water vapor condensation) were observed on all investigated iron minerals of abundant natural occurrence (i.e., goethite, hematite, and magnetite). The spontaneous •OH productions were triggered by contact electrification and Fenton-like activation of hydrogen peroxide (H2O2) at the water-iron mineral interface. Those •OH drove efficient transformation of organic pollutants associated on iron mineral surfaces. After 240 cycles of water vapor condensation and evaporation, bisphenol A and carbamazepine degraded by 25%-100% and 16%-51%, respectively, forming •OH-mediated arene/alkene hydroxylation products. Our findings largely broaden the natural source of •OH. Given the ubiquitous existence of iron minerals on Earth's surface, those newly discovered •OH could play a role in the transformation of pollutants and organic carbon associated with iron mineral surfaces.


Assuntos
Poluentes Ambientais , Ferro , Radical Hidroxila , Vapor , Peróxido de Hidrogênio , Minerais , Oxirredução
6.
Environ Sci Technol ; 57(23): 8628-8637, 2023 06 13.
Artigo em Inglês | MEDLINE | ID: mdl-37254500

RESUMO

Reactive oxygen species (ROS) play key roles in driving biogeochemical processes. Recent studies have revealed nonphotochemical electron transfer from redox-active substances (e.g., iron minerals) to oxygen as a new route for ROS production. Yet, naturally occurring iron minerals mainly exist in thermodynamically stable forms, restraining their potential for driving ROS production. Here, we report that tide-induced redox oscillations can activate thermodynamically stable iron minerals for enhanced ROS production. •OH production in intertidal soils (15.8 ± 0.5 µmol/m2) was found to be 5.9-fold more efficient than those in supratidal soils. Moreover, incubation of supratidal soils under tidal redox fluctuations dramatically enhanced •OH production by 4.3-fold. The tidal hydrology triggered redox alternation between biotic reduction and abiotic oxidation and could accelerate the production of reactive ferrous ions and amorphous ferric oxyhydroxides, making thermodynamically stable iron minerals into redox-active metastable iron phases (RAMPs) with reduced crystallinity and promoting surface electrochemical activities. Those RAMPs displayed enhanced redox activity for ROS production. Investigations of nationwide coastal soils verified that tide-induced redox oscillations could ubiquitously activate soils for enhanced ROS production. Our study demonstrates the effective formation of RAMPs from redox oscillations by hydrological perturbations, which provides new insights into natural ROS sources.


Assuntos
Ferro , Minerais , Ferro/química , Espécies Reativas de Oxigênio , Minerais/química , Compostos Férricos , Oxirredução , Solo
7.
Environ Sci Technol ; 56(16): 11888-11896, 2022 08 16.
Artigo em Inglês | MEDLINE | ID: mdl-35816724

RESUMO

We report an unrecognized, tidal source of reactive oxygen species (ROS). Using a newly developed ROS-trapping gel film, we observed hot spots for ROS generation within ∼2.5 mm of coastal surface soil. Kinetic analyses showed rapid production of hydroxyl radicals (•OH), superoxide (O2•-), and hydrogen peroxide (H2O2) upon a shift from high tide to low tide. The ROS production exhibited a distinct rhythmic fluctuation. The oscillations of the redox potential and dissolved oxygen concentration followed the same pattern as the •OH production, suggesting the alternating oxic-anoxic conditions as the main geochemical drive for ROS production. Nationwide coastal field investigations confirmed the widespread and sustainable production of ROS via tidal processes (22.1-117.4 µmol/m2/day), which was 5- to 36-fold more efficient than those via classical photochemical routes (1.5-7.6 µmol/m2/day). Analyses of soil physicochemical properties demonstrated that soil redox-metastable components such as redox-active iron minerals and organic matter played a key role in storing electrons at high tide and shuttling electrons to infiltrated oxygen at low tide for ROS production. Our work sheds light on a ubiquitous but previously overlooked tidal source of ROS, which may accelerate carbon and metal cycles as well as pollutant degradation in coastal soils.


Assuntos
Peróxido de Hidrogênio , Solo , Radical Hidroxila , Oxirredução , Oxigênio , Espécies Reativas de Oxigênio/metabolismo
8.
Macromol Rapid Commun ; 42(11): e2100085, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33864308

RESUMO

Continuous morphological control of anisotropic particles is always an important challenge in the field of materials. In this study, a new strategy for continuous fabrication of polymer particles with various morphologies induced by electricity is reported using complex emulsions as template. A synthetic electro-responsive surfactant containing ferrocene group is used to prepare complex emulsions, which contain a polymerizable monomer as inner phase. With the increasing time of electrical stimulation on the complex emulsions, hollow, hemispherical, mushroom-like, and spherical particles are constructed successively after photopolymerization. The Marangoni effect caused by the heterogeneity in the interfacial tension at the droplet surface is the reason for the reconfigurable morphology of the complex emulsion. The controllable complex emulsions by electricity present a versatile platform for constructing fine control of the microstructure and shape anisotropy of particles having customized shapes and functionalities, opening a new possibility for designing sophisticated architectures.


Assuntos
Polímeros , Tensoativos , Anisotropia , Emulsões , Tensão Superficial
9.
Anal Chem ; 92(12): 8081-8089, 2020 06 16.
Artigo em Inglês | MEDLINE | ID: mdl-32401011

RESUMO

In Raman-activated cell ejection and sequencing (RACE-Seq), success rate and sequence coverage have generally been low for shotgun sequencing of individual post-RACE cells. Here we quantitatively evaluated the influence of cell lysis condition, nucleic acid amplification condition, and parameters of Raman measurement on RACE-Seq performance. Variations in laser energy input during Raman signal acquisition, but not duration of alkaline lysate lysis, temperature, or measurement under dry or aqueous conditions, are vital to the success of multiple displacement amplification (MDA). In fact, laser irradiation is reversely linked to MDA product quality. However, introduction of oils prior to MDA, by mitigating such negative effects of Raman irradiation, elevates genome coverage of post-RACE Escherichia coli cells from <20% to ∼50%, while greatly improving the success rate of RACE-Seq for soil microbiota. Our findings provide a practical solution for enhancing RACE-Seq performance and pinpoint protection of cells from laser irradiation as a priority in method development.


Assuntos
DNA Bacteriano/genética , Escherichia coli K12/genética , Análise de Sequência de DNA , Escherichia coli K12/citologia , Técnicas de Amplificação de Ácido Nucleico , Análise Espectral Raman
10.
Chem Rev ; 118(10): 4946-4980, 2018 05 23.
Artigo em Inglês | MEDLINE | ID: mdl-29638112

RESUMO

Surface-enhanced Raman spectroscopy (SERS) inherits the rich chemical fingerprint information on Raman spectroscopy and gains sensitivity by plasmon-enhanced excitation and scattering. In particular, most Raman peaks have a narrow width suitable for multiplex analysis, and the measurements can be conveniently made under ambient and aqueous conditions. These merits make SERS a very promising technique for studying complex biological systems, and SERS has attracted increasing interest in biorelated analysis. However, there are still great challenges that need to be addressed until it can be widely accepted by the biorelated communities, answer interesting biological questions, and solve fatal clinical problems. SERS applications in bioanalysis involve the complex interactions of plasmonic nanomaterials with biological systems and their environments. The reliability becomes the key issue of bioanalytical SERS in order to extract meaningful information from SERS data. This review provides a comprehensive overview of bioanalytical SERS with the main focus on the reliability issue. We first introduce the mechanism of SERS to guide the design of reliable SERS experiments with high detection sensitivity. We then introduce the current understanding of the interaction of nanomaterials with biological systems, mainly living cells, to guide the design of functionalized SERS nanoparticles for target detection. We further introduce the current status of label-free (direct) and labeled (indirect) SERS detections, for systems from biomolecules, to pathogens, to living cells, and we discuss the potential interferences from experimental design, measurement conditions, and data analysis. In the end, we give an outlook of the key challenges in bioanalytical SERS, including reproducibility, sensitivity, and spatial and time resolution.


Assuntos
Materiais Biocompatíveis/análise , DNA/análise , Nanoestruturas/análise , Proteínas/análise , Análise Espectral Raman/normas , Técnicas Biossensoriais , Humanos , Propriedades de Superfície
11.
Anal Chem ; 91(13): 8383-8389, 2019 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-31140782

RESUMO

Intracellular pH is an important modulator of cell functions, and its subtle change may dramatically affect the cellular activities and cause diseases. A reliable imaging of the intracellular pH is still a great challenge. We imaged the intracellular pH during the cell cycle at the single living cell level using newly designed cell-penetrating peptide conjugated pH nanosensors on a home-built in situ microscopic cell culture platform. The conjugated cell-penetrating peptide greatly enhanced the uptake of nanosensors without sacrificing the pH response. We observed a gradual alkalization from interphase to prophase and rapid acidification from prometaphase to telophase, reflecting variation and consumption of the species related to the energy storage during cell cycle. We realized SERS-based pH and fluorescence dual-mode imaging when the pH sensor was further modified with fluorescence dye. The integration of SERS imaging with in situ microscopic cell culture system offers great opportunity for revealing the intracellular pH-related biological and pathological processes.


Assuntos
Técnicas Biossensoriais/métodos , Ciclo Celular , Peptídeos Penetradores de Células/química , Nanopartículas Metálicas/química , Nanotecnologia/métodos , Análise Espectral Raman/métodos , Neoplasias do Colo do Útero/patologia , Fenômenos Fisiológicos Celulares , Feminino , Corantes Fluorescentes/química , Ouro/química , Humanos , Concentração de Íons de Hidrogênio , Células Tumorais Cultivadas
12.
J Am Chem Soc ; 137(8): 2828-31, 2015 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-25671760

RESUMO

Constructing nanoparticles into well-defined structures at mesoscale and larger to create novel functional materials remains a challenge. Inspired by atomic epitaxial growth, we propose an "epitaxial assembly" method to form two-dimensional nanoparticle arrays (2D NAs) directly onto desired materials. As an illustration, we employ a series of surfactant-capped nanoparticles as the "artificial atoms" and layered hybrid perovskite (LHP) materials as the substrates and obtain 2D NAs in a large area with few defects. This method is universal for nanoparticles with different shapes, sizes, and compositions and for LHP substrates with different metallic cores. Raman spectroscopic and X-ray diffraction data support our hypothesis of epitaxial assembly. The novel method offers new insights into the controllable assembly of complex functional materials and may push the development of materials science at the mesoscale.

13.
Small ; 11(28): 3395-406, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25873340

RESUMO

Raman spectroscopy can not only provide intrinsic fingerprint information about a sample, but also utilize the merits of the narrow bandwidth and low background of Raman spectra, offering itself as a promising multiplex analytical technique. Raman microscopy has become particularly attractive recently because it has demonstrated itself as an important imaging technique for various samples, from biological samples and chemical systems to industrially important silicon-based wafers. In this Concept article, some of the most recent advances in Raman imaging techniques are critically reviewed, and the advantages and problems associated with the current techniques are discussed. Particular emphasis is placed on its future directions, from both the technical and application sides.


Assuntos
Teste de Materiais/métodos , Microscopia/tendências , Imagem Molecular/tendências , Nanotecnologia/tendências , Análise Espectral Raman/métodos , Tomografia Óptica/tendências
14.
Anal Chem ; 86(24): 12250-7, 2014 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-25418952

RESUMO

Local microenvironment pH sensing is one of the key parameters for the understanding of many biological processes. As a noninvasive and high sensitive technique, surface-enhanced Raman spectroscopy (SERS) has attracted considerable interest in the detection of the local pH of live cells. We herein develop a facile way to prepare Au-(4-MPy)-BSA (AMB) pH nanosensor. The 4-MPy (4-mercaptopyridine) was used as the pH sensing molecule. The modification of the nanoparticles with BSA not only provides a high sensitive response to pH changes ranging from pH 4.0 to 9.0 but also exhibits a high sensitivity and good biocompatibility, stability, and reliability in various solutions (including the solutions of high ionic strength or with complex composition such as the cell culture medium), both in the aggregation state or after long-term storage. The AMB pH nanosensor shows great advantages for reliable intracellular pH analysis and has been successfully used to monitor the pH distribution of live cells and can address the grand challenges in SERS-based pH sensing for practical biological applications.


Assuntos
Concentração de Íons de Hidrogênio , Nanopartículas , Soroalbumina Bovina/química , Análise Espectral Raman
15.
Anal Chem ; 86(4): 2238-45, 2014 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-24460183

RESUMO

Proteins perform vital functional and structural duties in living systems, and the in-depth investigation of protein in its native state is one of the most important challenges in the postgenomic era. Surface-enhanced Raman spectroscopy (SERS) can provide the intrinsic fingerprint information of samples with ultrahigh sensitivity but suffers from the reproducibility and reliability issues. In this paper, we proposed an iodide-modified Ag nanoparticles method (Ag IMNPs) for label-free detection of proteins. The silver nanoparticles provide the huge enhancement to boost the Raman signal of proteins, and the coated iodide layer offers a barrier to prevent the direct interaction between the proteins and the metal surface, helping to keep the native structures of proteins. With this method, highly reproducible and high-quality SERS signals of five typical proteins (lysozyme, avidin, bovine serum albumin, cytochrome c, and hemoglobin) have been obtained, and the SERS features of the proteins without chromophore were almost identical to the respective normal Raman spectra. This unique feature allows the qualitative identification of them by simply taking the intensity ratio of the Raman peaks of tryptophan to phenylalanine residues. We further demonstrated that the method can also be used for label-free multiplex analysis of protein mixture as well as to study the dynamic process of protein damage stimulated by hydrogen peroxide. This method proves to be very promising for further applications in proteomics and biomedical research.


Assuntos
Iodetos/química , Nanopartículas/química , Proteínas/análise , Análise Espectral Raman/métodos , Animais , Bovinos , Galinhas , Hemoglobinas/análise , Muramidase/análise , Soroalbumina Bovina/análise
16.
Sci Total Environ ; 916: 170414, 2024 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-38272084

RESUMO

Sunlight-induced photochemical transformations greatly affect the persistence of organic pollutants in natural environment. Whereas sunlight intensity is well-known to affect pollutant phototransformation rates, the reliance of pollutant phototransformation kinetics on sunlight spectrum remains poorly understood, which may greatly vary under different spatial-temporal, water matrix, and climatic conditions. Here, we systematically assessed the wavelength-dependent direct and indirect phototransformations of 12 organic pollutants. Their phototransformation rates dramatically decreased with light wavelength increasing from 375 to 632 nm, with direct photolysis displaying higher wavelength-dependence than indirect photolysis. Remarkably, UV light dominated both direct (90.4-99.5 %) and indirect (64.6-98.7 %) photochemical transformations of all investigated organic pollutants, despite its minor portion in sunlight spectrum (e.g., 6.5 % on March 20 at the equator). Based on wavelength-dependent rate constant spectrum, the predicted phototransformation rate of chloramphenicol (4.5 ± 0.7 × 10-4 s-1) agreed well with the observed rate under outdoor sunlight irradiation (4.3 ± 0.0 × 10-4 s-1), and there is no significant difference between the predicted rate and the observed rate (p-value = 0.132). Moreover, rate constant and quantum yield coefficient (QYC) spectrum could be applied for facilely investigate the influence of spectral changes on the phototransformation of pollutants under varying spatial-temporal (e.g., season, latitude) and climatic conditions (e.g., cloud cover). Our study highlights the wavelength-dependence of both direct and indirect phototransformation of pollutants, and the UV part of natural sunlight plays a decisive role in the phototransformation of pollutants.

17.
J Cheminform ; 16(1): 79, 2024 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-38972994

RESUMO

BACKGROUND: Previous deep learning methods for predicting protein binding pockets mainly employed 3D convolution, yet an abundance of convolution operations may lead the model to excessively prioritize local information, thus overlooking global information. Moreover, it is essential for us to account for the influence of diverse protein folding structural classes. Because proteins classified differently structurally exhibit varying biological functions, whereas those within the same structural class share similar functional attributes. RESULTS: We proposed LVPocket, a novel method that synergistically captures both local and global information of protein structure through the integration of Transformer encoders, which help the model achieve better performance in binding pockets prediction. And then we tailored prediction models for data of four distinct structural classes of proteins using the transfer learning. The four fine-tuned models were trained on the baseline LVPocket model which was trained on the sc-PDB dataset. LVPocket exhibits superior performance on three independent datasets compared to current state-of-the-art methods. Additionally, the fine-tuned model outperforms the baseline model in terms of performance. SCIENTIFIC CONTRIBUTION: We present a novel model structure for predicting protein binding pockets that provides a solution for relying on extensive convolutional computation while neglecting global information about protein structures. Furthermore, we tackle the impact of different protein folding structures on binding pocket prediction tasks through the application of transfer learning methods.

18.
Water Res ; 229: 119450, 2023 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-36495853

RESUMO

Black carbon (BC) is ubiquitous in sunlit waters and atomosphere. Recent studies revealed that under sunlight irradiation BC is photoactive on producing photochemically produced reactive intermediates (PPRIs), a group of key species in accelerating earth's surface biogeochemical processes and pollutant dynamics. Nevertheless, reported PPRIs productions from BC exhibit large inconsistency and the intrinsic capacities of BC in producing PPRIs remain poorly characterized. This work provided a wavelength-dependent quantum yields (QYs) assessment of four environmentally-relevant PPRIs (excited triplet state BC (3BC*), singlet oxygen (1O2), hydrogen peroxide (H2O2), and hydroxyl radical (·OH)) from various BC. The QYs of all investigated PPRIs exhibit high dependence on incident light wavelength. For instance, the QYs of 1O2 dramatically decreased from 4.4% to 0.4% with light wavelength increasing from 375 to 490 nm and decreased to 0 above 490 nm. Suprisingly, PPRIs QYs only varied by 2.0-2.5-fold among BC prepared from different biomasses (i.e., pine needle, shell, straw, and wood), while the pyrolysis temperature and size of BC demonstrate higher impacts on the PPRIs QYs by up to 30.3- and 7.1-fold variations, respectively. Analyses on the physicochemical properties of BC demonstrate that QYs of 3BC* and 1O2 were linked to the optical properties of BC, while the QYs of H2O2 and ·OH were determined by multiple factors including the surface redox characteristics. Further, PPRIs productions from BC follow similar paths and efficiencies compared to those from natural organic matter. The revealed QYs of BC-derived PPRIs establish a key basis for evaluating PPRIs-mediated element cycles and pollutant transformation in natural waters, which are becoming increasingly important in the context of higher BC input from more frequent wildfires and artificial sources.


Assuntos
Peróxido de Hidrogênio , Luz Solar , Oxigênio Singlete/química , Radical Hidroxila/química , Carbono
19.
Chemosphere ; 310: 136686, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36202373

RESUMO

Effective photoexcitation and carrier migration are the essential aspects to strengthen semiconductor-engaged redox reaction. Herein, a three-dimensional thin-wall hollow porous cystic-like g-C3N4 (HPCN) with curved layer edge was successfully fabricated via a non-template thermal-condensation strategy. The construction of unique distorted structure can evoke the hard-to-activate n→π* electronic transition to some extent, broadening the absorption spectrum to 800 nm. And benefiting from the multiple reflections of incident light, the effective photoactivation can be further achieved. Moreover, the thin-wall porous framework can shorten the diffusion distance and accelerate migration of photogenerated charge, favouring interfacial redox reactions. The optimized HPCN1.0 demonstrated an excellent photocatalytic degradation of SMX under blue-LED light irradiation, which was dramatically superior to that of pristine g-C3N4 (CN, 11.4 times). Ultimately, in consideration of reactions under several influencing factors with four different water samples, we demonstrated that the HPCN photocatalyst could be utilized far more productively for the elimination of SMX under real-world aqueous conditions. This work provides a straightforward approach for the removal of SMX and has immense potential to contribute to global scale environmental remediation.


Assuntos
Eletrônica , Sulfametoxazol , Porosidade , Catálise
20.
Pest Manag Sci ; 79(9): 3090-3102, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-36994611

RESUMO

BACKGROUND: Efficient deposition of high-speed droplets on superhydrophobic leaf surfaces remains an important challenge. For anisotropic wired superhydrophobic leaf surfaces, the splashing phenomenon is especially serious because it leads to the low effective utilization of pesticides by biological targets. The lost pesticides cause serious ecological environment pollution, therefore there is an urgent need to develop a green and sustainable cost-effective strategy to achieve efficient deposition of high-speed droplets on anisotropic superhydrophobic leaf surfaces at low dosage. RESULTS: One type of green pseudogemini surfactant is constructed based on fatty acids and hexamethylenediamine by electrostatic interaction to control the splashing and spreading of high-speed droplets on superhydrophobic surfaces. The formed surfactant can not only achieve complete inhibition of the bouncing of droplets, but also promote rapid spreading on superhydrophobic leaf surfaces at very low usage. The efficient deposition and superspreading phenomenon are attributed to the rapid migration and adsorption of the surfactant from the dynamic spherical micelles at the newly formed solid-liquid interface, the network-like aggregated spherical micelles, and the Marangoni effect caused by the surface tension gradient. Moreover, the surfactant shows an excellent synergistic effect with herbicides to control weeds by inhibiting droplet splashing. CONCLUSION: This work provides a simpler, more effective and sustainable approach to utilize aggregated spherical micelles rather than conventional vesicles or wormlike micelles to improve the droplet deposition on superhydrophobic leaf surfaces and reduce the impact of surfactants and pesticides on the ecological environment. © 2023 Society of Chemical Industry.


Assuntos
Praguicidas , Tensoativos , Tensoativos/farmacologia , Micelas , Folhas de Planta , Interações Hidrofóbicas e Hidrofílicas
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA