Concentrations Of Components Research Articles

Rapid Raman spectroscopy analysis assisted with machine learning: a case study on Radix Bupleuri.

Radix Bupleuri has been widely used for its plentiful pharmacological effects. But it is hard to evaluate their safety and efficacy because the concentrations of components are tightly affected by the surrounding environment. Thus, Radix Bupleuri samples from different regions and varieties were collected. Based on the experimental and computational Raman spectrum, machine learning is emphasized for certain obscured characteristics; for example, linear discriminant analysis (LDA), support vector machine (SVM), eXtreme gradient boosting (XGBoost) and light gradient boosting machine (LightGBM). After dimension reduction by LDA, models of SVM, XGBoost and LightGBM were trained for classification and regression prediction of Bupleurum production regions. Support vector classifiers achieved the best accuracy of 98% and an F1 score above 0.96 on the test set. Support vector regression has a good fitting performance with an R2 score above 0.90 and a relatively low mean square error. However, complex models were prone to overfitting, resulting in poor generalization ability. Among these machine learning models, the typical LDA-SVM models, consistent with the high-performance liquid chromatography results, demonstrate great performance and stability. We envision that this rapid classification and regression technique can be extended to predictions for other herbs. © 2024 Society of Chemical Industry.

Solvent- and Catalyst-Free Environmentally Benign High Hydrostatic Pressure-Assisted Synthesis of Bioactive Hydrazones and the Evaluation of Their Stability Under Various Storage Conditions

Our group has seen great promise in using substituted diaryl-hydrazones to alleviate oxidative stress in preeclampsia. Specifically, fluorinated diaryl-hydrazones have shown great efficacy, confirmed via antioxidant assays and animal trials using pregnant mice. In addition to efficient antioxidant properties, these diaryl-hydrazones are also considered non-toxic. While the synthesis of these compounds is relatively simple, it commonly utilizes undesirable solvents and glacial acetic acid as the catalyst; additional solvents are needed for the isolation of the desired products, which negatively affects the green synthesis of the hydrazones. To combat this possible industrial roadblock, we have begun incorporating the use of hydrostatic high pressure (HHP) in the synthesis. The use of HHP allowed us to synthesize substituted diaryl-hydrazones in a 1:1 molar ratio without the need for solvents or acid catalysts. The optimized procedure can produce nearly quantitative yields, leading to an easier isolation of the products. Different HHP methodologies, such as constant high-pressure treatment and cycling (with different number of cycles, holding and decompression times) were applied and cycling was observed to be the most efficient activation for the majority of the reactions. Stability experiments were also conducted with one of the products and observed that although the solid-state storage does not alter the hydrazone, storing it in various solvents may significantly decrease the concentration of the active component which should be considered when performing the biochemical/biological assays.

Chemical Profiles of Particulate Matter Emitted from Anthropogenic Sources in Selected Regions of China

Particulate matter (PM) emissions from anthropogenic sources contribute substantially to air pollution. The unequal adverse health effects caused by source-emitted PM emphasize the need to consider the discrepancy of PM-bound chemicals rather than solely focusing on the mass concentration of PM when making air pollution control strategies. Here, we present a dataset about chemical compositions of real-world PM emissions from typical anthropogenic sources in China, including industrial (power, industrial boiler, iron & steel, cement, and other industrial process), residential (coal/biomass burning, and cooking), and transportation sectors (on-road vehicle, ship, and non-exhaust emission). The data was obtained under the same strict quality control condition on field measurements and chemical analysis, minimizing the uncertainty caused by different study approaches. The concentrations of PM-bound chemical components, including toxic elements and PAHs, exhibit substantial discrepancies among different emission sectors. This dataset provides experimental data with informative inputs to emission inventories, air quality simulation models, and health risk estimation. The obtained results can gain insight into understanding on source-specific PMs and tailoring effective control strategies.

Continuous solid-phase extraction spectroscopy and its quantification method for trace analysis

This study designed and developed an innovative online detection device based on Continuous Solid-Phase Extraction Spectroscopy (CSPES) for rapid quantitative analysis of environmental water pollutants. The device is highly automated, eliminating environmental interference. Leveraging CSPES technology and adsorption kinetics theory, an online quantitative analysis model between the spectrum and component concentrations was established, along with a concentration calculation method based on the least squares method. The quantitative analysis method was validated using single-component and binary-component sample systems containing Fluoranthene, Benzo[k]Fluoranthene, and Rhodamine 6G. The model exhibited excellent predictive performance, with overall prediction concentration relative errors (RE) ranging from 0.45 % to 8.75 % and relative standard deviations (RSD) of less than 3 %. In real sample applications, recovery rates ranged from 86.8 % to 124.4 %, with RSDs between 0.33 % and 2.22 %. This method provides a robust tool for water quality monitoring and environmental analysis, holding significant potential for application across various fields.

The prospective associations of fetal growth-related pregnancy complications with subsequent breastfeeding duration and markers of human milk production.

The development of the breast for lactation occurs throughout pregnancy. It is unknown whether pregnancy complications resulting in poor fetal growth can affect breastfeeding success. We examined whether fetal growth-related pregnancy complications were associated with earlier breastfeeding cessation and changes in the concentrations of human milk biomarkers of low milk production. We used data from the Growing Up in Singapore Toward healthy Outcomes (GUSTO) study (n=954). Human milk concentrations of protein, lactose, citrate, sodium, potassium and zinc at 3 weeks postpartum were available for 180 mother-infant dyads. We examined the associations of fetal growth measures, including term infants born small-for-gestational-age (SGA) (<10th percentile), pregnancies complicated by fetal growth deceleration (FGD) (2nd - 3rd trimester fetal growth dropped between major centiles), elevated umbilical artery resistance (UAR) (> 90th percentile) or hypertensive disorders of pregnancy (HDP) with (i) risk of ceasing breastfeeding (Cox regression) and (ii) concentrations of human milk components (weighted linear regression). Adjusting for maternal education, smoking exposure, breastfeeding intentions and pre-pregnancy BMI, individuals who delivered SGA infants, and those with HDP were more likely to breastfeed for a shorter duration when compared to those with uncomplicated pregnancies (adjusted hazard ratio [95% CI]: 1.45 [1.11, 1.89] and 1.61 [1.14, 2.29], respectively); associations were not significant for FGD and UAR. SGA was not associated with concentrations of human milk biomarkers, but compared to participants with uncomplicated pregnancies, milk produced by those with HDP contained lower zinc concentrations (adjusted beta coefficient [95% CI]: -0.56 mg/L [-1.08, -0.04]). Individuals with HDP and those with SGA infants tend to breastfeed for a shorter duration; however, only HDP appeared to be associated with biomarkers of compromised milk production. Further research and support are needed to help individuals with HDP and SGA achieve their breastfeeding goals. This study was registered as NCT01174875, and can be accessed at https://clinicaltrials.gov/study/NCT01174875.

Comprehensive analysis of bacterial succession and flavor components in Xiguajiang with different watermelon juice supplementation during fermentation

This study investigated the physicochemical factors, bacterial communities, and volatile aromatic components in watermelon soybean pastes (WSP) prepared with different ratios of different watermelon juice to koji during the fermentation process. The results indicated that high concentration of watermelon juice could significantly increase the contents of amino acid nitrogen, reducing sugar, and free amino acids, but decreased bacterial diversity. Enterococcus, Bacillus, Enterobacter, Staphylococcus, Pediococcus, Lactobacillus, and Weissella were identified as the dominant genus bacteria in WSP samples, while Enterococcus and Pediococcus were found to account for more than 50% in WSP-4 samples. In WSP samples, this study identified 142 volatile components, the concentration of volatile components was more abundant in WSP-4 samples compared to WSP-2 and WSP-3 samples, especially in the pyrazine family. Furthermore, E-nose results showed that the influence of watermelon juice on the aroma components of WSP samples was mainly focused on the late fermentation periods, but aroma profiles were relatively similar in all WSP samples regardless of watermelon juice concentration throughout the fermentation period. Therefore, this study discovered that controlling the amount of watermelon juice and fermentation time can affect the aroma profiles of WSP samples to a certain extent, and improve the industrial production and food quality.

Features of changes in nonspecific factors of immunological reactivity in obesity

Introduction. The study of pathogenetic factors of obesity is an urgent task of modern medicine. The formation of obesity is characterized by changes in the activity of individual mechanisms of innate immunity. At the same time, the values of laboratory indicators that characterize them are often within the current boundaries of the reference values of laboratory indicators of the immunity of a healthy person. This complicates the pathogenetic assessment of the mechanisms of nonspecific immunological reactivity in obesity and determines the need for further study of the characteristics of nonspecific immune defense factors in this pathology.Aim. To identify the features of changes in cellular and humoral factors of nonspecific immunological reactivity in obesity.Materials and methods. A single-center cross-sectional, one-time controlled study was conducted with the participation of 118 people, of which 87 people were obese patients (BMI 37.2 [34.1; 42.05] kg/m2), 31 people had normal body weight (BMI 21.9 [ 20.2; 23.5] kg/m2) and were included in the control group. All patients underwent a study of lipid profile (total cholesterol, high-density lipoproteins, low-density lipoproteins, very low-density lipoproteins, triglycerides), carbohydrate metabolism (glucose, insulin, glycated hemoglobin), C-reactive protein, indicators of cellular and humoral factors of nonspecific immunity (leukogram, cytokine profile, C3-C4 complement components).Results. An increase in the total number of leukocytes was revealed, due to neutrophil granulocytes against the background of the development of a disproportion between the percentage and absolute value of the number of lymphocytes and monocytes, the concentration of C3 and C4 complement components, C-reactive protein, as well as an increase in the level of IL-6, which confirms the presence of low-grade chronic inflammation in obese patients. Statistically significant correlations of immunological parameters with anthropometric data, indicators of carbohydrate and lipid metabolism were revealed.Conclusion. The results of the study indicate that obesity causes activation of certain cellular and humoral mechanisms of nonspecific immune defense involved in the formation of the inflammatory process. Confirmation of the presence of a latent inflammatory process in obesity is an increase in the level of leukocytes and their individual cellular forms, C-reactive protein, C3 and C4 complement components, IL-6. A feature of the changes is the presence of fluctuations in the values of the studied indicators within the current boundaries of the reference values of laboratory indicators, which makes it difficult to timely diagnose chronic inflammation in obesity

High-performance red mud as an electrocatalyst for nitrate reduction toward ammonia synthesis

Red mud (RM) is a solid waste generated in the aluminum industry after the extraction of alumina oxide; its multiple elements and higher pH value likely pose a severe threat to the environment after treatment. However, RM's higher concentrations of metal components, particularly Fe2O3 and rare earth elements (REEs), render RM promising for catalytic application. Hence, this work showed an efficient high-speed RM to catalyze electrocatalytic nitrate-to-ammonia reduction reaction (NARR). RM calcined at 500 °C (RM-500) exhibited excellent catalytic performance. Faradaic efficiency of ammonia (FENH3) in an electrolyte solution containing 1 mol/L NO3− achieved a maximum value of 92.3% at −0.8 V (vs. RHE). Additionally, 24-hour cycle testing and post-reaction PXRD and SEM indicated that the RM-500 electrocatalyst is stable during NARR. The RM-500 demonstrated a high FE of NH3-to-NO3− of 89.7% at 1.85 V (vs. RHE), showing great potential in the ammonia fuel cells technology and achieving the nitrogen cycle.

Airway epithelium damage in acute respiratory distress syndrome

BackgroundThe airway epithelium (AE) fulfils multiple functions to maintain pulmonary homeostasis, among which ensuring adequate barrier function, cell differentiation and polarization, and actively transporting immunoglobulin A (IgA), the predominant mucosal immunoglobulin in the airway lumen, via the polymeric immunoglobulin receptor (pIgR). Morphological changes of the airways have been reported in ARDS, while their detailed features, impact for mucosal immunity, and causative mechanisms remain unclear. Therefore, this study aimed to assess epithelial alterations in the distal airways of patients with ARDS.MethodsWe retrospectively analyzed lung tissue samples from ARDS patients and controls to investigate and quantify structural and functional changes in the small airways, using multiplex fluorescence immunostaining and computer-assisted quantification on whole tissue sections. Additionally, we measured markers of mucosal immunity, IgA and pIgR, alongside with other epithelial markers, in the serum and the broncho-alveolar lavage fluid (BALF) prospectively collected from ARDS patients and controls.ResultsCompared to controls, airways of ARDS were characterized by increased epithelial denudation (p = 0.0003) and diffuse epithelial infiltration by neutrophils (p = 0.0005). Quantitative evaluation of multiplex fluorescence immunostaining revealed a loss of ciliated cells (p = 0.0317) a trend towards decreased goblet cells (p = 0.056), and no change regarding cell progenitors (basal and club cells), indicating altered mucociliary differentiation. Increased epithelial permeability was also shown in ARDS with a significant decrease of tight (p < 0.0001) and adherens (p = 0.025) junctional proteins. Additionally, we observed a significant decrease of the expression of pIgR, (p < 0.0001), indicating impaired mucosal IgA immunity. Serum concentrations of secretory component (SC) and S-IgA were increased in ARDS (both p < 0.0001), along other lung-derived proteins (CC16, SP-D, sRAGE). However, their BALF concentrations remained unchanged, suggesting a spillover of airway and alveolar proteins through a damaged AE.ConclusionThe airway epithelium from patients with ARDS exhibits multifaceted alterations leading to altered mucociliary differentiation, compromised defense functions and increased permeability with pneumoproteinemia.

Nanosecond Pulse-Driven Oxygen Bubble Plasma Activation of Low-Concentration Alcohol Solutions and its Sterilization Mechanism.

To address the current use of high-concentration (70-75%) alcohol solutions as disinfectants, which are known for their drawbacks such as flammability and strong odor, a new approach based on nanosecond pulse-driven bubble discharge in low-concentration ethanol solutions is proposed. Research findings indicate that O2 bubble plasma activated ethanol solution (PAES) exhibits superior sterilization efficacy. A 3 min treatment using 10% alcohol eliminated all bacteria (reducing the bacterial count by 7 orders of magnitude) with an energy requirement of only 10.9 J/ml, whereas the same treatment with air PAES achieved less than a one-order reduction and O2/N2/air plasma activated water (PAW) achieved even less. Furthermore, to delve deeper into the key factors of PAES sterilization, concentrations of inorganic reactive species (H2O2, NO2 -, NO3 -, ONOO-, pH) and organic components resulting from alcohol decomposition (CH3CHO, CH3CH2OH, CH3COOH, and CH3COOOH) were analyzed using assay kits and GC-MS. Their variations at different storage temperatures (4 °C and -20 °C) were compared with the corresponding bactericidal effects. The results identified peroxyacetic acid (CH3COOOH) as a key bactericidal factor in PAES, showing that CH3COOOH over time at different storage temperatures correlated with their bactericidal effects. The study also revealed that O2 PAES stored at -20 °C maintained complete bacterial elimination even after 4 days. Therefore, PAES has the potential to replace high-concentration alcohol solutions for sterilization.

Theoretical framework for calibrating the depth-dependent optical scattering in layered human skin using spatially offset measurements.

Spatially offset spectroscopy offers an alternative non-invasive method for enabling deep probing of structures and chemical molecules, which is clinically significant for the characterization of chemical and physical alterations in human skin. However, a more precise depth-resolved quantification using the spatially offset measurements still remains a challenge due to the mixed inhomogeneous scattering. Herein, we report a Monte-Carlo-based quantification modeling platform combined with a novel, to the best of our knowledge, scattering spectrum decomposition method to explore the depth-dependent optical scattering contributions in human skin. In the simplified modeling, human skin was empirically set to be composed of multiple layers, and each layer possessed different photon weights for the spatially offset scattering intensity measurements. The modeling results of photon transportation in-and-out of the layered skin substantially discovered that the layer-dependent scattering contribution was compositely encoded into the spatially offset measurements and varied with the illumination incidence angle. For calibrating the layer-dependent scattering contribution, a modified nonlinear independent component processing algorithm was applied to the spatially offset measurements by decomposing the photon weights of each layer. The calibration results figured out the major scattering contribution of each layer along the offset axis under different incidence angles, which were consistent with previous experimental observations. The proposed theoretical framework establishes a feasible approach for spatially offset optical spectroscopies enabling non-invasive quantitative A-line characterization of the concentrations of skin components.

Development of a chemical mechanism for ammonia/hydrogen blends for engines

ABSTRACT Ammonia/hydrogen blend fuels have been extensively used as alternative fuel for engines. The combustion and emissions characteristics of ammonia/hydrogen engines have been investigated utilising a CFD model. Developing a robust and accurate chemical reaction mechanism for ammonia/hydrogen blend fuels is of utmost importance. In this paper, a chemical mechanism has been developed and validated for the combustion characteristics of ammonia/hydrogen, which includes 31 species and 223 reactions. Extensive validation has been conducted using experimental data as the basis. The obtained data indicate that the simulated values for the ignition delay times of the shock tube and the concentration of the main components in the stirred jet reactor align well with the measured values. The simulated laminar flame speed under turbulent flow conditions shows a remarkable agreement with the corresponding experimental data. The study compared simulated flame evolution values with experimental data from a constant volume combustion bomb. The results indicate that the proposed mechanism is able to produce favourable flame evolution and combustion characteristics. The presented detailed mechanism demonstrates credible overall performance in terms of combustion behaviours, indicating its suitability for effectively modelling ammonia/hydrogen combustion in real engines.

Main spatial-temporal regularities of the state of the chemical composition of groundwater of the oligocene aquifer in the Shaim oil and gas bearing area

The constantly growing need for fresh water in the Shaim oil and gas region necessitates the exploration of new areas and the development of measures to improve the operation of water intakes. To predict the quality of groundwater, which is an operational parameter of the aquifer aquifer, it is needed up-to-date information on the chemical composition of ground-water. The aim of this study to identify main spatial-temporal regularities of the state of the chemical composition of groundwater of the oligocene aquifer in the Shaim oil and gas bearing area, compared to average values from adjacent areas. Research methods include the systematization of laboratory data on water samples, analysis of groundwater chemistry, and mapping of the main spatial-temporal patterns in component concentration changes. The average values of chemical composition indicators in the studied area are similar to those of neighbouring areas, with some indicators exceeding drinking water standards. Similarities are observed in the variability of the chemical composition, spatial patterns of changes in most chemical indicators, and the presence of areas with extreme values. Current data on the chemical composition of the oligocene aquifer ground-water, including key characteristics and spatial-temporal trends presented in distribution maps, can be used in designing groundwater intakes and forecasting long-term groundwater quality.

Numerical Study of the Combustion Process in the Vertical Heating Flue of Air Staging Coke Oven

To investigate the combustion process and reduce Nitric Oxide (NO) emissions in the vertical heating flue of air-staged coke ovens, a three-dimensional computational fluid dynamics method was applied to simulate the combustion process. The model integrates the k-ε turbulence model with a multi-component transport combustion model. The impact of air staging on the flow field and NO emissions in the vertical fire chamber was assessed through comparative validation with experimental data. The impact of air staging on the flow field and NO emissions in the vertical fire chamber was assessed through comparative validation with experimental data. Based on this research, the effects of the excess air coefficient and air inlet distribution ratio on NO emission levels at the flue gas outlet were further investigated. Analysis of the flow field structure, temperature at the center cross-section, component concentration, and NO emission levels indicates that as the excess air coefficient increases, the NO emission levels at the flue gas outlet initially decrease and then increase, accompanied by corresponding changes in outlet temperature. At an air excess factor of 1.3 and an air inlet distribution ratio of 7:3, NO emission levels are at their lowest—53% lower than those in a conventional coke oven—and the temperature distribution in the riser channel is more uniform. These results provide a theoretical foundation for designing the air-staged coke oven standing fire channel structure.

CFD Investigation on Air-Staged Combustion Characteristics of Deep Peak Shaving Wall-Fired Burner Boilers

ABSTRACT In alignment with China’s ambitious goals of reaching peak carbon emissions and achieving carbon neutrality, stringent load peak regulations are being enforced for coal-fired power generation. This underlines the significance of deploying deep load peaking strategies in coal-fired units. The current research focus is on wall-fired boilers operating under ultra-low loads of 600 MWe. It delves into the flow dynamics, combustion characteristics, component concentration field, and NOx emission characteristics under varying air coefficients in the primary combustion zones (α). The findings suggest the formation of a consistently high-temperature region in the primary combustion zone, where temperatures surpass 1500 K. The middle burner exhibits superior combustion stability compared to the bottom burner. As α diminishes, several changes occur. The flow field intensity in the primary combustion zone lessens, the ignition distance contracts, and the O2 concentration in this area drops. This engenders a reducing atmosphere characterized by low O2 and high CO levels, which hampers the formation of NOx. At α = 0.95, the NO concentration peaks, with the primary generation mechanism being temperature-driven. At this juncture, the NO concentration at the furnace flue gas outlet is 287.36 mg/m3.

The Biological Effect of Enriching the Plasma Content in Platelet-Rich Plasma: An In Vitro Study.

Platelet-rich plasma (PRP) formulations have become valuable therapeutic tools in regenerative medicine. In addition, these blood derivates have been successfully included in cell therapy as fetal bovine serum substitutes, due to the real need to avoid the risk of host immunologic reactions and the animal disease transmission associated with reagents from animal origin. However, the protocols for obtaining them should be optimized to improve their biological potential. PRP-derived preparations with different concentrations of the platelet and plasma components were obtained from the blood of five donors by freeze-drying. Measurements of the pH, protein, and growth factor concentration were performed. Moreover, their biological effects on cell proliferation and migration and their angiogenic potential were assessed. An increased plasma component concentration resulted in an augmented quantity of the total protein content, a significative variation in the hepatocyte growth factor concentration, and an experimental but clinically irrelevant alteration of the pH value. No significant changes were induced in their potential to enhance proliferative and migratory responses in epithelial cells, with the latter being reduced for dermal fibroblasts. The endothelial cell capacity for tube formation was significatively reduced. An increased blood plasma content did not improve the biological potential of the formulations. However, they have emerged as a promising approach for regenerative therapies where neovascularization must be avoided.

Numerical Investigation on the Effect of Air Humidification and Oxygen Enrichment on Combustion and Emission Characteristics of Gas Boiler

Gas boilers exhibit thermal inefficiency and unsatisfying pollutant emissions. In this study, numerical simulations were conducted to examine the effect of humidified oxygen-enriched air on methane combustion in a furnace and the effects of different premixed ratios of air on the temperature field inside the furnace, intermediate product OH groups, component concentration distribution, and pollutants. Although humidification of ambient air effectively reduced the flame center temperature and mass concentration of the NOx generated during combustion in the furnace, the highest growth rate of CO concentration at the furnace outlet was 18.6%. Humidification of oxygen-enriched air increased the center temperature and outlet NO concentration of the furnace compared with those during no oxygen enrichment, but the outlet CO concentration showed a decreasing trend, with the highest decrease rate of 34.6%. This study determined an optimal CO–air premix ratio with a moisture concentration of 50 g/kg dry air and an oxygen concentration of 23%. The air humidification and oxygen enrichment technology proposed in this article provides a technical reference for low nitrogen transformation of existing gas boilers.

Hydrochemical variation characteristics and driving factors of surface water in arid Areas—a case study of Beichuan River in Northwest China

Examining the chemical properties of river water and the controlling factors is crucial for devising efficacious strategies in water resources management and ecological conservation. This study investigates the hydrochemical characteristics and driving factors of the Beichuan River in the arid region of Northwest China. Surface water samples were collected during wet and dry seasons, and analyzed using hydrochemical diagrams, mathematical statistics, and principal component analysis (PCA). The results show that the pH value of Beichuan River is generally weakly alkaline, the main hydrochemical types are HCO3-Ca, and the average TDS are 224 mg/L and 236 mg/L respectively, which are higher than the world average level (115 mg/L). The seasonal variation of hydrochemical components is mainly controlled by rainfall, showing that the concentrations of Na+, Cl− and NO3− in the wet season are higher than those in the dry season, while the concentrations of other chemical components show an opposite trend, while the spatial variation is mainly controlled by human activities, and the concentrations of hydrochemical components show a gradual increasing trend from upstream to downstream, especially Na+, Mg2+, Cl− and NO3−. Rock weathering is the key natural factor controlling the Hydrochemical Composition of Beichuan River. Na+ and Cl− are mainly from the dissolution of silicate, Ca2+ and Mg2+ are mainly from the weathering of carbonate rocks and silicate, and SO42- is mainly from the dissolution of evaporite. It is noted that human activities, especially domestic sewage and agricultural runoff, contribute significantly to NO3− in the water body. PCA identified rock weathering and agricultural runoff as major wet-season factors, while domestic sewage predominantly affects the dry season. This study can provide a scientific basis for the rational development of water resources and ecological environment protection in arid areas.

Speedy Component Resolution Using Spatially Encoded Diffusion NMR Data.

Diffusion-ordered NMR spectroscopy (DOSY) is a powerful tool to analyse mixtures. Spatially encoded (SPEN) DOSY enables recording a full DOSY dataset in just one scan by performing spatial parallelisation of the gradient dimension. The simplest and most widely used approach to processing DOSY data is to fit each peak in the spectrum with a single or multiple exponential decay. However, when there is peak overlap, and/or when the diffusion decays of the contributing components are too similar, this method has limitations. Multivariate analysis of DOSY data, which is an attractive alternative, consists of decomposing the experimental data, into compound-specific diffusion decays and 1D NMR spectra. Multivariate analysis has been very successfully used for conventional DOSY data, but its use for SPEN DOSY data has only recently been reported. Here, we present a comparison, for SPEN DOSY data, of two widely used algorithms, SCORE and OUTSCORE, that aim at unmixing the spectra of overlapped species through a least square fit or a cross-talk minimisation, respectively. Data processing was performed with the General NMR Analysis Toolbox (GNAT), with custom-written code elements that now expands the capabilities, and makes it possible to import and process SPEN DOSY data. This comparison is demonstrated on three different two-component mixtures, each with different characteristics in terms of signal overlap, diffusion coefficient similarity, and component concentration.

Long-range transport of air pollutants increases the concentration of hazardous components of PM2.5 in northern South America

Abstract. Long-range transport (LRT) of air pollutants from a range of sources can substantially enhance background pollution levels, especially in urbanized regions, which can exacerbate high-pollution episodes. In the Aburrá Valley (AV), Colombia, and other cities in northern South America, biomass burning (BB), dust, and volcanic degassing have been identified as sources of long-range aerosol transport. However, the impact of these sources on air quality and the characterization of these sources have yet to be thoroughly studied. This work investigates the influence of these sources on the chemical composition of PM2.5 during annual and intra-annual high-load aerosol events in the AV. We identified, tracked, and meteorologically characterized LRT events and evaluated their influence on PM2.5 concentration and chemical composition. We found that the LRT of aerosols from BB, dust, and volcanic degassing influenced approximately 13 %, 8 %, and 13 % of days in the year, respectively. We applied the positive-matrix-factorization (PMF) statistical model to quantify PM2.5 concentrations and chemical compositions for the different LRT event types (e.g., BB). For BB events, we identified large contributions from organic carbon (OC1 and OC2), F−, and secondary aerosol tracers (SO42- and NO3-). For dust LRT events, crustal mineral components, along with Ti and Ca, were the primary contributors to aerosol composition, while SO42-, Na, Al, and Ca were the primary contributors during volcanic events. The concentrations of some ions and toxic heavy metals (Cr, Mn, Cd, and Ni) were also elevated during BB and volcanic-degassing events. BB contributed the most to PM2.5 levels during the LRT events (∼11 µg m−3), while contributions from aerosols arising from dust and volcanic events were also substantial (&lt;7 µg m−3). Our study identifies the Orinoco and the Middle Magdalena Valley as sizable sources of BB aerosols and Nevado del Ruiz as a source of volcanic aerosols. Additionally, we found that African dust reached the Andean region via the Caribbean route. As a result, we identify the need for future chemical-transport modeling studies in the region and new support strategies to manage internal and external pollution sources that degrade air quality in the AV and the surrounding region.