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1.
Anal Chim Acta ; 1177: 338785, 2021 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-34482890

RESUMO

The methanol sensors are of significance to maintain the efficient and stable operation of direct methanol fuel cells (DMFCs). The issues, including stability, the relationship between temperature, current density and concentration need, however, urgent attention. A novel electrochemical methanol sensor which is based on current output limited by methanol diffusion is developed. The stability of sensors was lifted steeply through introducing a reference electrode, narrowing the methanol flow channel, and adding a water container. The relationship between the temperature, response current and methanol concentration was determined with the help of theoretical derivation and the validity was verified by the fitting result. Other sensors can avail of this relationship to correct the temperature effect. Application test indicated that the sensor may be of great potential for the accurate monitoring of methanol concentration at the levels of DMFCs application.


Assuntos
Metanol , Água , Difusão , Temperatura
2.
Anal Chim Acta ; 1177: 338790, 2021 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-34482898

RESUMO

For the first time, Diffusive Gradient in Thin-films (DGT) focuses on the inorganic iodine species iodate (IO3-) and iodide (I-). A silver-doped Cl resin (AgdCl), which is known to selectively accumulate I-, was used to make a binding gel. Laboratory investigations were designed to verify the suitability of the AgdCl-DGT method to measure the total I- concentration in environmental waters. Total recovery of I- was obtained using an elution solution containing 100 mmol L-1 KCN. DGT validation experiments in 10 mmol L-1 NaCl showed linear accumulation of I- over time, contrary to IO3-, thus confirming the selectivity of AgdCl-binding gel. The AgdCl-DGT measurement of total I- concentration was independent of pH (4.5-8.8) and was not impacted by the presence of bicarbonate (1-5 mmol L-1). Finally, the performance of AgdCl-DGT samplers were tested in two continental waters and a synthetic seawater. The AgdCl-DGT samplers measured 27-33% of the total I- concentration in the two continental waters up to 24 h of deployment time, whereas the AgdCl-DGT response retrieved the total I- concentration in seawater up to 72 h (106 ± 7%). The difference in DGT response was attributed to the low ionic strength of the two continental waters, limiting the application of AgdCl-DGT method to media with higher ionic strength.


Assuntos
Monitoramento Ambiental , Poluentes Químicos da Água , Difusão , Iodetos , Água do Mar , Poluentes Químicos da Água/análise
3.
Chaos ; 31(8): 083125, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34470253

RESUMO

In the present article, we demonstrate the emergence and existence of the spiral wave chimera-like transient pattern in coupled ecological systems, composed of prey-predator patches, where the patches are connected in a three-dimensional medium through local diffusion. We explore the transition scenarios among several collective dynamical behaviors together with transient spiral wave chimera-like states and investigate the long time behavior of these states. The transition from the transient spiral chimera-like pattern to the long time synchronized or desynchronized pattern appears through the deformation of the incoherent region of the spiral core. We discuss the transient dynamics under the influence of the species diffusion at different time instants. By calculating the instantaneous strength of incoherence of the populations, we estimate the duration of the transient dynamics characterized by the persistence of the chimera-like spatial coexistence of coherent and incoherent patterns over the spatial domain. We generalize our observations on the transient dynamics in a three-dimensional grid of diffusive ecological systems by considering two different prey-predator systems.


Assuntos
Quimera , Ecossistema , Difusão
4.
Environ Monit Assess ; 193(10): 650, 2021 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-34523050

RESUMO

In view of the advantages of CFD technology in the simulation of small and medium-scale chemical hazard diffusion, one near-field prediction model of chemical hazard diffusion named CHDNFP is constructed based on CFD technology, and the accuracy and efficiency of the model are improved by improved differential evolution algorithm (DEA) and fireworks algorithm (FWA). Firstly, based on the component conservation equation, momentum conservation equation, and turbulence control equation, CHDNFP model is constructed, whose basic solution process is proposed from three aspects: non-uniform mesh refinement in diffusion space, model discretization, and iterative solution of control equation. Secondly, comprehensive considering the global search ability, local search ability, and convergence characteristics of integrated DEA and FWA, a hybrid optimization algorithm IDEFWA is designed, which is suitable for predictive model solving. Finally, the CHDNFP model and IDEFWA are verified by tracer experiments. The result shows that: IDEFWA can reduce the relative root mean square error between the predicted concentration field and the observed concentration field to about 25%, with the calculation accuracy of 10-19 and the standard deviation accuracy of 10-9; compared with ABCA and GA, IDEFWA can get more accurate solutions faster under the same algebraic and population conditions; the calculation accuracy of CHDNFP-IDEFWA and PISOFOAM is almost the same, where the relative difference is about 3%, and CHDNFP-IDEFWA has better calculation accuracy than PISOFOAM, which is improved by about 26.05%.


Assuntos
Algoritmos , Monitoramento Ambiental , Simulação por Computador , Difusão
5.
Sensors (Basel) ; 21(16)2021 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-34450906

RESUMO

The production process of a wafer in the semiconductor industry consists of several phases such as a diffusion and associated defectivity test, parametric test, electrical wafer sort test, assembly and associated defectivity tests, final test, and burn-in. Among these, the fault detection phase is critical to maintain the low number and the impact of anomalies that eventually result in a yield loss. The understanding and discovery of the causes of yield detractors is a complex procedure of root-cause analysis. Many parameters are tracked for fault detection, including pressure, voltage, power, or valve status. In the majority of the cases, a fault is due to a combination of two or more parameters, whose values apparently stay within the designed and checked control limits. In this work, we propose an ensembled anomaly detector which combines together univariate and multivariate analyses of the fault detection tracked parameters. The ensemble is based on three proposed and compared balancing strategies. The experimental phase is conducted on two real datasets that have been gathered in the semiconductor industry and made publicly available. The experimental validation, also conducted to compare our proposal with other traditional anomaly detection techniques, is promising in detecting anomalies retaining high recall with a low number of false alarms.


Assuntos
Algoritmos , Semicondutores , Difusão
6.
Sensors (Basel) ; 21(16)2021 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-34451105

RESUMO

This paper presents the first photoplethysmographic (PPG) signal dynamic-based biometric authentication system with a Siamese convolutional neural network (CNN). Our method extracts the PPG signal's biometric characteristics from its diffusive dynamics, characterized by geometric patterns in the (p,q)-planes specific to the 0-1 test. PPG signal diffusive dynamics are strongly dependent on the vascular bed's biostructure, unique to each individual. The dynamic characteristics of the PPG signal are more stable over time than its morphological features, particularly in the presence of psychosomatic conditions. Besides its robustness, our biometric method is anti-spoofing, given the complex nature of the blood network. Our proposal trains using a national research study database with 40 real-world PPG signals measured with commercial equipment. Biometric system results for input data, raw and preprocessed, are studied and compared with eight primary biometric methods related to PPG, achieving the best equal error rate (ERR) and processing times with a single attempt, among all of them.


Assuntos
Identificação Biométrica , Biometria , Bases de Dados Factuais , Difusão , Redes Neurais de Computação
7.
Molecules ; 26(15)2021 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-34361707

RESUMO

The mechanism by which proteins are solvated in hydrated ionic liquids remains an open question. Herein, the photoexcitation dynamics of photoactive yellow protein dissolved in hydrated choline dihydrogen phosphate (Hy[ch][dhp]) were studied by transient absorption and transient grating spectroscopy. The photocyclic reaction of the protein in Hy[ch][dhp] was similar to that observed in the buffer solution, as confirmed by transient absorption spectroscopy. However, the structural change of the protein during the photocycle in Hy[ch][dhp] was found to be different from that observed in the buffer solution. The known change in the diffusion coefficient of the protein was apparently suppressed in high concentrations of [ch][dhp], plausibly due to stabilization of the secondary structure.


Assuntos
Proteínas de Bactérias/química , Líquidos Iônicos/química , Fosforilcolina/química , Fotorreceptores Microbianos/química , Água/química , Tampões (Química) , Difusão , Luz , Solubilidade , Análise Espectral/métodos
8.
Int J Mol Sci ; 22(16)2021 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-34445534

RESUMO

Enzymes activity in a cell is determined by many factors, among which viscosity of the microenvironment plays a significant role. Various cosolvents can imitate intracellular conditions in vitro, allowing to reduce a combination of different regulatory effects. The aim of the study was to analyze the media viscosity effects on the rate constants of the separate stages of the bacterial bioluminescent reaction. Non-steady-state reaction kinetics in glycerol and sucrose solutions was measured by stopped-flow technique and analyzed with a mathematical model developed in accordance with the sequence of reaction stages. Molecular dynamics methods were applied to reveal the effects of cosolvents on luciferase structure. We observed both in glycerol and in sucrose media that the stages of luciferase binding with flavin and aldehyde, in contrast to oxygen, are diffusion-limited. Moreover, unlike glycerol, sucrose solutions enhanced the rate of an electronically excited intermediate formation. The MD simulations showed that, in comparison with sucrose, glycerol molecules could penetrate the active-site gorge, but sucrose solutions caused a conformational change of functionally important αGlu175 of luciferase. Therefore, both cosolvents induce diffusion limitation of substrates binding. However, in sucrose media, increasing enzyme catalytic constant neutralizes viscosity effects. The activating effect of sucrose can be attributed to its exclusion from the catalytic gorge of luciferase and promotion of the formation of the active site structure favorable for the catalysis.


Assuntos
Glicerol/metabolismo , Luciferases/química , Luciferases/metabolismo , Modelos Teóricos , Photobacterium/enzimologia , Sacarose/metabolismo , Catálise , Domínio Catalítico , Difusão , Simulação de Dinâmica Molecular , Viscosidade
9.
Nat Commun ; 12(1): 5042, 2021 08 19.
Artigo em Inglês | MEDLINE | ID: mdl-34413297

RESUMO

Food production must increase significantly to sustain a growing global population. Reducing plant water loss may help achieve this goal and is especially relevant in a time of climate change. The plant cuticle defends leaves against drought, and so understanding water movement through the cuticle could help future proof our crops and better understand native ecology. Here, via mathematical modelling, we identify mechanistic properties of water movement in cuticles. We model water sorption in astomatous isolated cuticles, utilising three separate pathways of cellulose, aqueous pores and lipophilic. The model compares well to data both over time and humidity gradients. Sensitivity analysis shows that the grouping of parameters influencing plant species variations has the largest effect on sorption, those influencing cellulose are very influential, and aqueous pores less so but still relevant. Cellulose plays a significant role in diffusion and adsorption in the cuticle and the cuticle surfaces.


Assuntos
Celulose/metabolismo , Plantas/metabolismo , Água/metabolismo , Adsorção , Transporte Biológico , Difusão , Secas , Umidade , Modelos Biológicos , Permeabilidade , Epiderme Vegetal/metabolismo , Folhas de Planta/metabolismo
10.
Anal Chem ; 93(35): 11937-11945, 2021 09 07.
Artigo em Inglês | MEDLINE | ID: mdl-34432435

RESUMO

Plutonium, americium, and uranium contribute to the radioactive contamination of the environment and are risk factors for elevated radiation exposure via ingestion through food or water. Due to the significant environmental inventory of these radioelements, a sampling method to accurately monitor their bioavailable concentrations in natural waters is necessary, especially since physicochemical factors can cause significant temporal fluctuations in their waterborne concentrations. To this end, we engineered novel diffusive gradients in thin-film (DGT) configurations using resin gels, which are selective for UO22+, Pu(IV + V), and Am(III) among an excess of extraneous cations. In this work, we also report an improved synthesis of our in-house ion-imprinted polymer resin, which we used to manufacture a resin gel to capture Am(III). The effective diffusion coefficients of Pu, Am, and U in agarose cross-linked polyacrylamide were determined in freshwater and seawater simulants and in natural seawater, to calibrate these configurations for environmental deployments.


Assuntos
Plutônio , Urânio , Amerício/análise , Difusão , Água Doce , Plutônio/análise , Urânio/análise
11.
Anal Chem ; 93(36): 12472-12479, 2021 09 14.
Artigo em Inglês | MEDLINE | ID: mdl-34455787

RESUMO

Single-particle levitation methods provide an effective platform for probing the physical properties of atmospheric aerosol via micrometer-sized particles. Until recently, chemical composition measurements on levitated particles were limited to spectroscopy, yielding only basic chemical information. Here, we describe, benchmark, and discuss the applications of an approach for probing the physical properties and chemical composition of single levitated particles using high-resolution mass spectrometry (MS). Using a linear quadrupole electrodynamic balance (LQ-EDB) coupled to paper spray mass spectrometry, we report accurate measurements of the evolving size within 5 nm (using broadband light scattering) and relative composition (using MS) of evaporating multicomponent levitated particles in real time. Measurements of the evaporation dynamics of semivolatile organic particles containing a range of n-ethylene glycols (n = 3, 4, and 6) in various binary and ternary mixtures were made under dry conditions and compared with predictions from a gas-phase diffusion evaporation model. Under assumptions of ideal mixing, excellent agreement for both size and composition evolution between measurements and models were obtained for these mixtures. At increased relative humidity, the presence of water in particles causes the assumption of ideality to break down, and the evaporative mass flux becomes a function of the mole fraction and activity coefficient. Through compositionally resolved evaporation measurements and thermodynamic models, we characterize the activity of organic components in multicomponent particles. Our results demonstrate that the LQ-EDB-MS platform can identify time-dependent size and compositional changes with high precision and reproducibility, yielding an effective methodology for future studies on chemical aging and gas-particle partitioning in suspended particles.


Assuntos
Evolução Química , Aerossóis , Difusão , Tamanho da Partícula , Reprodutibilidade dos Testes
12.
Water Sci Technol ; 84(3): 697-711, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34388128

RESUMO

Carboxylic acids are the main pollutant of industrial wastewater during the advanced oxidation process (AOPs). In this study, a resin-based spherical activated carbon (RSAC, AF5) as an adsorbent was examined and acetic acid was used as a model substrate for adsorption investigation. The pH = 3, temperature = 298 K were fixed by batch technique. The pseudo-second-order kinetic model, the intraparticle and external models are fitted well, and it was found that the adsorption of acetic acid onto AF5 was controlled by liquid film diffusion. A Freundlich model indicated that the adsorption process was heterogeneous multimolecular layer adsorption on the surface. AF5 shows good regenerative ability; the recovery rate of adsorption capacity was ∼88% after five cycles. Chemical oxygen demand (COD) adsorption removal rate could be maintained at 100% for over 35 h in an actual AOPs effluent, and could be eluted for 100% after 8 h by 0.8wt% NaOH. Characterizations, including XRF, XRD, TG/DSC,FTIR, SEM and N2 adsorption, showed that the excellent adsorption performance was mainly due to the microporous structure and large specific surface area (1,512.88 m2/g), the adsorption mechanism mainly included pore filling effect and electrostatic attraction. After five adsorption recycles, AF5's pore characteristic did not change significantly. This study provides a scientific basis for the wastewater standard discharge process of AOPs coupled adsorption.


Assuntos
Carvão Vegetal , Poluentes Químicos da Água , Ácido Acético , Adsorção , Difusão , Concentração de Íons de Hidrogênio , Cinética , Termodinâmica
13.
Sci Total Environ ; 790: 148194, 2021 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-34380251

RESUMO

Fluoroquinolones (FQs) have raised significant concerns due to their ubiquitous occurrence and promoting of antimicrobial resistance (AMR). In this study, a molecularly imprinted polymer-diffusive gradient in thin-films (MIP-DGT) sampler is developed for selective measurement of FQs in waters by using a commercial available MIP material as the binding agent. The MIP-DGT shows selective adsorption of the FQs and linearly accumulates the FQs over the deployment time. MIP-DGT measurement is independent of pH (6-8) and ionic strength (IS) (0.01-0.5 M) but is affected by DOM at higher concentrations (~10 mg•L-1), which is due to the altered diffusion coefficients and reduced adsorption on the MIP binding gel. Significant interaction effects of DOM with pH or IS indicate that this is the predominant influence on the MIP-DGT performance, which results in a lower measurement by the MIP-DGT but this is curtailed to some extend with increasing IS or pH. The MIP-DGT measurements, however, correlate well with those by grab sampling in a wastewater treatment plant, suggesting it is reliable for measuring FQs in waters. For the first time, we demonstrate that key water chemistry parameters do have interaction effects on the DGT measurements, which should be considered for the data interpretation. The MIP-DGT is a promising tool to understand the interaction effects of the environmental parameters on the fate, behaviours and bioavailability/toxicity of organic contaminants and improve environmental risk assessments in the environment and modelling.


Assuntos
Monitoramento Ambiental , Poluentes Químicos da Água , Antibacterianos/análise , Difusão , Fluoroquinolonas , Polímeros Molecularmente Impressos , Poluentes Químicos da Água/análise
14.
Int J Nanomedicine ; 16: 4713-4737, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34267519

RESUMO

Background: Amiodarone (AMD) is a widely used anti-arrhythmic drug, but its administration could be associated with varying degrees of pulmonary toxicity. In attempting to circumvent this issue, AMD-loaded polymeric nanoparticles (AMD-loaded NPs) had been designed. Materials and Methods: AMD was loaded in NPs by the nanoprecipitation method using two stabilizers: bovine serum albumin and Kolliphor® P 188. The physicochemical properties of the AMD-loaded NPs were determined. Among the prepared NPs, two ones were selected for further investigation of spectral and thermal analysis as well as morphological properties. Additionally, in vitro release patterns were studied and kinetically analyzed at different pH values. In vitro cytotoxicity of an optimized formula (NP4) was quantified using A549 and Hep-2 cell lines. In vivo assessment of the pulmonary toxicity on Sprague Dawley rats via histopathological and immunohistochemical evaluations was applied. Results: The developed NPs achieved a size not more than 190 nm with an encapsulation efficiency of more than 88%. Satisfactory values of loading capacity and yield were also attained. The spectral and thermal analysis demonstrated homogeneous entrapment of AMD inside the polymeric matrix of NPs. Morphology revealed uniform, core-shell structured, and sphere-shaped particles with a smooth surface. Furthermore, the AMD-loaded NPs exhibited a pH-dependent and diffusion-controlled release over a significant period without an initial burst effect. NP4 demonstrated a superior cytoprotective efficiency by diminishing cell death and significantly increasing the IC50 by more than threefold above the pure AMD. Also, NP4 ameliorated AMD-induced pulmonary damage in rats. Significant downregulation of inflammatory mediators and free radicle production were noticed in the NP4-treated rats. Conclusion: The AMD-loaded NPs could ameliorate the pulmonary injury induced by the pure drug moieties. Cytoprotective, anti-fibrotic, anti-inflammatory, and antioxidant properties were presented by the optimized NPs (NP4). Future studies may be built on these findings for diminishing AMD-induced off-target toxicities.


Assuntos
Amiodarona/química , Amiodarona/toxicidade , Portadores de Fármacos/química , Pulmão/efeitos dos fármacos , Nanopartículas/química , Copolímero de Ácido Poliláctico e Ácido Poliglicólico/química , Células A549 , Animais , Morte Celular/efeitos dos fármacos , Difusão , Células Hep G2 , Humanos , Tamanho da Partícula , Ratos , Ratos Sprague-Dawley
15.
Anal Chem ; 93(30): 10644-10652, 2021 08 03.
Artigo em Inglês | MEDLINE | ID: mdl-34279080

RESUMO

In UHPLC, frictional heating from the eluent flowing through the column at pressures of ca. 10-15 Kpsi causes radial diffusion via temperature differences between the center of the column and its walls. Longitudinal dispersion also occurs due to temperature gradients between the inlet and outlet. These effects cause band broadening but can be mitigated via a combination of vacuum jacketed stainless steel tubing, reduced column end nut mass, and a constant temperature in the column from heating the inlet fitting. Here, vacuum jacketed column (VJC) technology, employing a novel column housing located on the source of the mass spectrometer and minimized tubing from the column outlet to the electrospray probe, was applied to profiling metabolites in urine. For a 75 s reversed-phase gradient separation, the average peak widths for endogenous compounds in urine were 1.2 and 0.6 s for conventional LC/MS and VJC systems, respectively. The peak tailing factor was reduced from 1.25 to 1.13 when using the VJC system compared to conventional UHPLC, and the peak capacity increased from 65 to 120, with a 25% increase in features detected in urine. The increased resolving power of the VJC system reduced co-elution, simplifying MS and MS/MS spectra, providing a more confident metabolite identification. The increased LC performance also gave more intense MS peaks, with a 10-120% increase in response, improving the quality of the MS data and detection limits. Reducing the LC gradient duration to 37 s gave peak widths of ca. 0.4 s and a peak capacity of 84.


Assuntos
Espectrometria de Massas em Tandem , Cromatografia Líquida de Alta Pressão , Cromatografia Líquida , Difusão , Vácuo
16.
Soft Matter ; 17(29): 6910-6928, 2021 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-34235519

RESUMO

Cell membranes - primarily composed of lipids, sterols, and proteins - form a dynamic interface between living cells and their environment. They act as a mechanical barrier around the cell while selectively facilitating material transport, signal transduction, and various other functions necessary for the cell viability. The complex functionality of cell membranes and the hierarchical motions and responses they exhibit demand a thorough understanding of the origin of different membrane dynamics and how they are influenced by molecular additives and environmental cues. These dynamic modes include single-molecule diffusion, thermal fluctuations, and large-scale membrane deformations, to name a few. This review highlights advances in investigating structure-driven dynamics associated with model cell membranes, with a particular focus on insights gained from neutron scattering and spectroscopy experiments. We discuss the uniqueness of neutron contrast variation and its remarkable potential in probing selective membrane structure and dynamics on spatial and temporal scales over which key biological functions occur. We also present a summary of current and future opportunities in synergistic combinations of neutron scattering with molecular dynamics (MD) simulations to gain further understanding of the molecular mechanisms underlying complex membrane functions.


Assuntos
Bicamadas Lipídicas , Lipídeos de Membrana , Membrana Celular , Difusão , Simulação de Dinâmica Molecular
17.
Anal Chem ; 93(28): 9697-9703, 2021 07 20.
Artigo em Inglês | MEDLINE | ID: mdl-34227809

RESUMO

A novel approach, concentration-ordered NMR spectroscopy (CORDY), is being proposed based on the principle that the ratio of the NMR peak area to its associated number of spins is proportional to the concentration of the assigned compound. Besides, prior information of chemical shift distribution and line shape characteristics of different chemical groups is utilized to shrink the solution space. CORDY generates a pseudo-two-dimensional NMR spectrum with chemical shifts in one axis and concentrations in the other, resulting in both separation and quantitation of components in complex samples. The method was validated by application to three samples-a model mixture containing six amino acids, sugar-free Red Bull, and human urine. It was demonstrated that CORDY could successfully separate the components with up to 2 orders of magnitude in the concentration dimension for the samples used in the current study. In addition, a combination of CORDY and DOSY (CORDY-DOSY) has been found to be more efficient in resolving the molecules with similar concentrations or self-diffusion coefficients.


Assuntos
Carboidratos , Imageamento por Ressonância Magnética , Aminoácidos , Difusão , Humanos , Espectroscopia de Ressonância Magnética
18.
Anal Chem ; 93(29): 10365-10371, 2021 07 27.
Artigo em Inglês | MEDLINE | ID: mdl-34258992

RESUMO

Moment theory was applied to the kinetic study of intermolecular interactions. The association equilibrium constant (KA) and association (ka) and dissociation (kd) rate constants of chemical reactions were analytically determined on the basis of the moment theory from elution peak profiles measured by high-performance liquid chromatography (HPLC). The HPLC data were measured under the conditions that neither immobilization nor fluorescence labeling of solute and ligand molecules is required. These are the advantages of the moment analysis method for determining accurate values of KA, ka, and kd. Moment equations were developed on the basis of the Einstein equation for diffusion, the random walk model, and the general rate model of chromatography. The moment analysis method was applied to the inclusion complex formation system between dibenzo-18-crown-6 or dibenzo-15-crown-5 and alkali metal cations. It was demonstrated that the values of KA, ka, and kd can be determined on the assumption that the stoichiometry between crown ethers and cations is 1:1 or 2:1. The influence of the difference in the size between the inner cavity of crown ethers and cations on the association and dissociation of the inclusion complex was considered. The moment analysis method using HPLC is effective for analyzing intermolecular interactions from various perspectives because it is based on the separation technique and has different characteristics from other methods such as spectroscopy. The results of this study contribute to the dissemination of an opportunity for studying intermolecular interactions from equilibrium and kinetic points of view to many researchers because HPLC is widespread.


Assuntos
Cinética , Cromatografia Líquida de Alta Pressão , Difusão , Ligantes , Soluções
19.
Anal Chem ; 93(31): 10772-10778, 2021 08 10.
Artigo em Inglês | MEDLINE | ID: mdl-34320315

RESUMO

Untargeted metabolomics using liquid chromatography coupled to mass spectrometry (LC-MS) allows the detection of thousands of metabolites in biological samples. However, LC-MS data annotation is still considered a major bottleneck in the metabolomics pipeline since only a small fraction of the metabolites present in the sample can be annotated with the required confidence level. Here, we introduce mWISE (metabolomics wise inference of speck entities), an R package for context-based annotation of LC-MS data. The algorithm consists of three main steps aimed at (i) matching mass-to-charge ratio values to the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, (ii) clustering and filtering the potential KEGG candidates, and (iii) building a final prioritized list using diffusion in graphs. The algorithm performance is evaluated with three publicly available studies using both positive and negative ionization modes. We have also compared mWISE to other available annotation algorithms in terms of their performance and computation time. In particular, we explored four different configurations for mWISE, and all four of them outperform xMSannotator (a state-of-the-art annotator) in terms of both performance and computation time. Using a diffusion configuration that combines the biological network obtained from the FELLA R package and raw scores, mWISE shows a sensitivity mean (standard deviation) across data sets of 0.63 (0.07), while xMSannotator achieves a sensitivity of 0.55 (0.19). We have also shown that the chemical structures of the compounds proposed by mWISE are closer to the original compounds than those proposed by xMSannotator. Finally, we explore the diffusion prioritization separately, showing its key role in the annotation process. mWISE is freely available on GitHub (https://github.com/b2slab/mWISE) under a GPL license.


Assuntos
Algoritmos , Metabolômica , Cromatografia Líquida , Difusão , Espectrometria de Massas , Software
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