- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Elucidating molecular level impact of peat fire on soil organic matter by laser desorption ionization Fourier transform ion cyclotron resonance mass spectrometry
摘要： In this work, laser desorption ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry (LDI–FTICRMS) was used to investigate the molecular composition of a peat fire and laboratory heated soil organic matter (SOM). SOM isolated from soils obtained from unburned and burned sites at Central Kalimantan, Indonesia, were analyzed with LDI–FTICRMS. About 7500 peaks were found and assigned with molecular formulas for each mass spectrum. SOM isolated from fire-affected soil sites are relatively more abundant in low oxygenated classes (e.g., O1–O5) and thermally stable compounds, including condensed hydrocarbon and nitrogen heterocyclic compounds. Abundances of highly condensed hydrocarbon compounds with carbon number > 30 were increased for the fire-affected SOM. In vivo heating experiments were conducted for SOM extracted from unburned sites, and the prepared SOMs were analyzed with LDI–FTICRMS. Overall, the same trend of change at the molecular level was observed from both the laboratory heated and the peat fire-affected SOM samples. In addition, it was observed that heat caused the degradation of SOM, generating lignin and tannin-type molecules. It was hypothesized that they were formed by thermal degradation of high molecular weight SOM. All the information presented in this study was obtained by consuming ~ 5 μg of sample. Therefore, this study shows that LDI–FTICRMS is a sensitive analytical technique that is effective in obtaining molecular level information of SOM.
关键词： Soil organic matter,Molecular transformation,LDI–FTICRMS,Peat fire
更新于2025-09-11 14:15:04
-
Flower-like gold nanoparticles for enhanced photothermal anticancer therapy by the delivery of pooled siRNA to inhibit heat shock stress response
摘要： Reported reaction kinetics of metal nanoparticles in natural and engineered systems commonly have used proxy measurements to infer chemical transformations, but extension of these methods to complex media has proven difficult. Here, we compare the sulfidation rate of AgNPs using two ion selective electrode (ISE)-based methods, which rely on either (i) direct measurement of free sulfide, or (ii) monitor the free Ag+ available in solution over time in the presence of sulfide species. Most experiments were carried out in moderately hard reconstituted water at pH 7 containing fulvic acid or humic acid, which represented a broad set of known interferences in ISE. Distinct differences in the measured rates were observed between the two proxy-based methods and details of the divergent results are discussed. The two ISE based methods were then compared to direct monitoring of AgNP chemical conversion to Ag2S using synchrotron-based in situ X-ray diffraction (XRD). Using XRD, distinct rates from both ISE-based technique were observed, which demonstrated that ISE measurements alone are inadequate to discriminate both the rate and extent of AgNP sulfidation. XRD rate data elucidated previously unidentified reaction regimes that were associated with AgNP coating (PVP and citrate acid) and NOM components, which provided new mechanistic insight into metallic NP processing. In general, the extent of Ag2S formation was inversely proportional to surface coverage of the initial AgNP. Overall, methods to determine reaction kinetics of nanomaterials in increasingly complex media and heterogeneous size distributions to improve NP-based design and performance will require similar approaches.
关键词： ion selective electrode,X-ray diffraction,natural organic matter,silver nanoparticles,sulfidation kinetics
更新于2025-09-11 14:15:04
-
Dynamic intermolecular interactions control adsorption from mixtures of natural organic matter and protein onto titanium dioxide nanoparticles
摘要： Engineered nanoparticles (NPs) will obtain macromolecular coatings in environmental systems, changing their subsequent interactions. The matrix complexity inherent in natural waters and wastewaters greatly complicates prediction of the corona formation. Here, we investigate corona formation on titanium dioxide (TiO2) NPs from mixtures of natural organic matter (NOM) and a protein, bovine serum albumin (BSA), to thoroughly probe the role of mixture interactions in the adsorption process. Fundamentally different coronas were observed under different NP exposure conditions and time scales. In mixtures of NOM and protein, the corona composition was kinetically determined, and the species initially co-adsorbed but were ultimately limited to monolayers. On the contrary, sequential exposure of the NPs to pure solutions of NOM and protein resulted in extensive multilayer formation. The intermolecular complexation between NOM and BSA in solution and at the NP surface was the key mechanism controlling these distinctive adsorption behaviors, as determined by size exclusion chromatography (SEC) and in situ attenuated total reflectance – Fourier transform infrared (ATR-FTIR) spectroscopy. Overall, this study demonstrates that dynamic intermolecular interactions and the history of the NP surface must be considered together to predict corona formation on NPs in complex environmental media.
关键词： corona formation,adsorption,bovine serum albumin,Engineered nanoparticles,titanium dioxide nanoparticles,natural organic matter,intermolecular interactions
更新于2025-09-11 14:15:04
-
Marine coastal zones monitoring by shipborne semiautomatic passive optical complex
摘要： For studying of the environmental status of marine coastal areas, it is often necessary to obtain operatively detailed data about water constituents and their distribution over the area. The three-channel passive optical complex for Ecological Monitoring of Marine Areas (EMMA), developed by us, was applied in the Feodosia Bay, the Black Sea, to obtain remotely the absorption indices for the suspended matter, coloured dissolved organic matter, and phytoplankton pigments. It operated from board a vessel for more than 4 h and gave data for approximately 15,000 sea radiance coe?cient spectra. The obtained spectra were processed by the original method giving possibility to suppress negative in?uence of the weather and experiment conditions and to get the absorption index spectra of the water constituents. The data of shipborne remote sensing using EMMA were compared to the estimates retrieved from the measurements on water samples taken at special stations on the route; their correlation turned out to be quite reasonable. The distributions of the suspended matter and coloured organic matter, obtained remotely over the studied area, were discussed. This research showed the possibility of EMMA application for ground truth measurements and for exploring the sea areas close to the coastal line, which cannot be seen from satellites because of cloudiness.
关键词： phytoplankton pigments,coloured dissolved organic matter,marine coastal zones,suspended matter,absorption indices,monitoring,Black Sea,semiautomatic passive optical complex,EMMA,shipborne
更新于2025-09-11 14:12:44
-
Characterization and bioavailability of rainwater dissolved organic matter at the southeast coast of China using absorption spectroscopy and fluorescence EEM-PARAFAC
摘要： Rainwater brings considerable amounts of dissolved organic matter (DOM) from atmosphere to freshwater and marine environments, but little is known about the chemical composition and bioavailability of rainwater DOM. The quantity, quality, and bioavailability of DOM were investigated for 21 rain events at a coastal site in southeast China, using dissolved organic carbon (DOC) measurements, absorption spectroscopy, and fluorescence excitation-emission matrices-parallel factor analysis (EEM-PARAFAC). The DOC concentration ranged from 35 to 457 μM, which was affected by the prevailing monsoon, rainfall amount and terrestrial/anthropogenic inputs. The volume-weighted average DOC was 118 μM, corresponding to a rainwater DOC flux of 1.98 g m?2 yr?1. Four fluorescent components were identified with EEM-PARAFAC, including three humic-like components (C1-C3) and one tyrosine-like component C4. Absorption coefficient (aCDOM(300)) and fluorescence intensities of C2-C4 strongly correlated with DOC, indicating they can be used for DOC estimation. Rainwater DOM was characterized by low DOC-specific UV absorbance (SUVA254) and humification index (HIX), which indicated a low aromaticity and humification degree. Principal component analysis (PCA) based on DOM indices revealed two principal factors, which were related to the DOM concentration and humification degree respectively. PCA, together with air-mass trajectory analysis, successfully separated different rain events with variable inputs from living plants/local sources, soil organic matter/humified materials, and the marine source. Rainwater DOM generally showed a high bioavailability of 50% ± 19%, with higher degradability of non-chromophoric constituents and C1-C2 than other components. This study demonstrated the applicability of absorption and EEM-PARAFAC combined with PCA and air-mass trajectory analysis in differentiating rain events and tracking organic matter sources, and revealed different effects of microbial degradation on individual PARAFAC components in rainwater.
关键词： Dissolved organic matter,Absorption spectroscopy,EEM-PARAFAC,Rainwater,Bioavailability
更新于2025-09-10 09:29:36
-
Electrospray-Surface Enhanced Raman Spectroscopy (ES-SERS) for probing surface chemical compositions of atmospherically relevant particles
摘要： We present electrospray-surface enhanced Raman spectroscopy (ES-SERS) as a new approach to measuring the surface chemical compositions of atmospherically relevant particles. The surface-sensitive SERS is realized by electrospraying Ag nanoparticle aerosols over analyte particles. Spectral features at v(SO42-), v(C-H) and v(O-H) modes were observed from the normal Raman and SERS measurements of laboratory-generated supermicron particles of ammonium sulfate (AS), AS mixed with succinic acid (AS/SA) and AS mixed with sucrose (AS/sucrose). SERS measurements showed strong interaction (or chemisorption) between Ag nanoparticles and surface aqueous sulfate [SO42-] with [SO42-]AS/sucrose > [SO42-]AS/SA > [SO42-]AS. Enhanced spectra of the solid AS and AS/SA particles revealed the formation of surface-adsorbed water on their surfaces at 60% relative humidity. These observations of surface aqueous sulfate and adsorbed water demonstrate a possible role of surface-adsorbed water in facilitating the dissolution of sulfate from the bulk phase into its water layer(s). Submicron ambient aerosol particles collected in Hong Kong exhibited non-enhanced features of black carbon and enhanced features of sulfate and organic matter (carbonyl group), indicating an enrichment of sulfate and organic matter on the particle surface.
关键词： Electrospray-Surface Enhanced Raman Spectroscopy,succinic acid,atmospherically relevant particles,surface chemical compositions,ES-SERS,sucrose,Ag nanoparticles,surface-adsorbed water,organic matter,ammonium sulfate,black carbon
更新于2025-09-09 09:28:46
-
Dark recovery of photodegraded dissolved organic matter as a source of a protein-like fluorophore in natural waters
摘要： Excitation-emission matrix (EEM) fluorescence spectroscopy is being widely used to characterize dissolved organic matter in aquatic environments. The main types of fluorophores in natural waters, defined by this technique, are humic-like and the protein-like ones. The latter is generally thought to be of biological origin. In this study, we show that the emergence of the protein-like fluorophore may be the result of DOM phototransformation. Samples of natural waters were irradiated using ultraviolet radiation in the solar wavelength range. Their EMM spectra were recorded before and directly after irradiation, and after 72 h long dark storage. Fluorescence of the photodegraded water samples partially recovered during the storage. The highest increase in fluorescence was observed in the spectral range ascribed to the protein-like fluorophore. It suggests that microbial production is not the only source of this component of DOM.
关键词： Dissolved organic matter,Photodegradation,Protein-like fluorescence
更新于2025-09-09 09:28:46