Chemical Components Research Articles

Aligners: review of their chemical components, recycling, mechanical properties and therapeutic needs - Part 1

The aligner is a thermoformed plastic device composed of various chemical components: polyurethane, polyethylene terephthalate glycol, polypropylene…All these plastics must be sufficiently resistant to abrasion and translucent for aesthetic purposes, but their solubility to salivary enzymes, insertion-disinsertion fatigue and recyclability vary according to material. From an orthodontic point of view, they must facilitate tooth movement. However, their behavior differs from that of orthodontic archwires: their Young's modulus, resilience and unloading curve are distinct, resulting in mechanical properties that fall significantly below the orthodontic requirements of multi-bracket systems. The aim of this article was to review the chemical composition, recycling and mechanical properties of aligners, and to put them into perspective with therapeutic indications. Literature data were approximated to orthodontic needs. Neither plastic nor direct printing can match the mechanical properties of our archwires or the procedures of a reliable vestibular multi-attachment appliance. Aligners remain an interesting tool in targeted indications.

A Data-Driven DNN Model to Predict the Ultimate Strength of a Ship’s Bottom Structure

Plates and curved plates are essential components in ship construction. In the design stage, the methods used to evaluate the ultimate strength required to confirm the structural safety of plates include prediction through analytical methods, finite-element analysis (FEA), and empirical formulas. However, with nonlinear buckling, the results of the empirical formula and the FEA differ for small flank angles (1~9). As a result, the prediction of the nonlinear ultimate strength of flank angle (1~9) plates still requires significant computation time and cost. To compensate for this, this study performed an ultimate strength prediction method utilizing a deep neural network together with the 4050 curved plate analysis. In addition, this paper presents the analysis results of the nonlinear finite-element method and the geometric shape and ratio of curved plates as training data. Based on the results of this study, designers can more efficiently design appropriate curved plate members by considering the ultimate strength.

Investigation on Calm Water Resistance of Wind Turbine Installation Vessels with a Type of T-BOW

Given the typical characteristics of self-propulsion and jack-up wind turbine installation vessels (WTIVs), including their full and blunt hull form and complex appendages, this paper combines the model test method with the RANS-based CFD numerical prediction method to experimentally and numerically study the resistance of the optimized hull at different spudcan retraction positions. The calm water resistance components and their mechanisms of WTIVs based on T-BOW were obtained. Furthermore, using the multivariate nonlinear least squares method, an empirical formula for rapid resistance estimation based on the Holtrop method was derived, and its prediction accuracy and applicability were validated with a full-scale ship case. This study indicates that the primary resistance components of such low-speed vessels are viscous pressure resistance, followed by frictional resistance and wave-making resistance. Notably, the spudcan retraction well area, as a unique appendage of WTIVs, exhibits a significant “moonpool additional resistance” effect. Different spudcan retraction positions affect the total calm water resistance by approximately 20% to 30%. Therefore, in the resistance optimization design of WTIVs, special attention should be paid to the matching design of the spudcan structure and the hull shell plate lines in the spudcan retraction well area.

Estimation and Management of Wind Energy in Ikorodu Lagos Lagoon, Using Weibull Parametric Measurement to Electricity Production in Nigeria

This paper is an approach on the estimation and approximation management of wind energy production around the lagoon axis of Ikorodu, Lagos state, Nigeria. The article concentrates on the availability of renewable resource such as wind to generate electrical energy in the greater Ikorodu metropolis of Lagos state Nigeria. Here, probability distribution function is used to generate the wind data. In this paper, three distinct methods are presented; Data time series analysis, Weibull probability function, and theoretical comparison with analytical concept. This research uses two important parameters for analyzing wind data: shape factor “k” and scale factor “c” from Weibull distribution function. The theoretical uses mathematical equations of popular methods such as: (a) Moment method, (b) Empirical Formula, or statistical standard deviation, (c) Peak likelihood, (d) modified peak likelihood, (e) double modified peak likelihood (f) graphical method or smallest mean square, and (g) energy sequence factor. The results obtained are tested to optimize the value from the Weibull parameters by adopting five techniques: (i) root average square error methodology, X2, power of agreement , MAPE, and RRMSE. The results expatiated on the practical and theoretical techniques design to confront the outcome of wind energy harnessed per 1.5 km2. Here, a differential optimization technique is used to determine the precision report. This serve as the basis of error litmus check existing between the wind energy determined by theory of statistical and mathematical Weibull Parametric function and the practical time-series data analysis in LSTM. Again, the wind data (speed and energy/power) were measured and recorded between January 2020 to December 2023 in the Ijede-Ikorodu Lagoon area of Lagos State. The optimized value for the shape factor k and scale factor c parametric measurement and management for maximizing the output electrical energy are obtained by using a well robust Weibull distribution function techniques and by absolutely determining and selecting the best position and location for installing the wind/wave alternators/generator. These generators come with turbines as a single unit. The measurement of the yearly average wind speed and average wind power are 10.09 ms-1 and 10.1 KWm-2, concurrently.

Impact of thermal treatment on the properties of assacú (Hura crepitans L.) and murici (Byrsonima crispa A.Juss.) Amazon woods

Background: White and low-density Amazon woods, such as assacú (Hura crepitans L.) and murici (Byrsonima crispa A.Juss.), have restricted use, given their low physical-mechanical strength and low natural durability. Physicochemical changes caused by heat treatment can improve different quality traits of these woods, such as changing the visual appearance from white to brown tones, improving dimensional stability, moisture control, and resistance to attack from biological organisms. Methods: Assacú and murici wood samples were heat treated (180 and 220°C) for 60 minutes in a muffle kiln. The physical (moisture, mass loss, density, shrinkage, swelling), mechanical (dynamic modulus of elasticity), and chemical (extractives, solubility in hot water, lignin, and holocellulose) properties were evaluated following treatment and compared with those measured before treatment. Results: The heat treatments T2 (180°C) and T3 (220°C) reduced the moisture content; however, the T3 treatment caused a more intense mass loss. For murici wood, this mass loss was 14%. The anisotropy coefficient was reduced for assacú wood by 1.30 and 1.03% for the T2 and T3 treatments, respectively, improving the dimensional stability of this wood. The density and modulus of elasticity were affected by the treatment, thus reducing the strength of the wood. The extractive content of the woods increased by 4.99 and 7.49% for sampled of assacú and murici, respectively, that were treated at 220°C. For the primary metabolites, holocellulose and lignin, degradation of these compounds occurred due to the decrease in their concentrations. The linear analysis of the studied variables indicated a high correlation between the physical properties and the chemical components of the woods (e.g., anisotropy coefficient x lignin and holocellulose x apparent density, r > 0.95). Conclusions: The heat treatment of Amazon woods directly influenced their physical-mechanical and chemical properties. In general, the higher temperature treatment caused the greatest changes in the studied species, and the exposure to heat caused noticeable changes in their colour. Heat treatment is a useful process for the forestry sector since heat-treated wood can be used to manufacture high-value-added products, such as fine furniture, residential floors, musical instruments, and non-structural components.

Phytochemical Composition and Antimicrobial and Antibiofilm Effect of Myrciaria cauliflora Hydroethanolic Extract against Staphylococcus aureus and Acinetobacter baumannii

Staphylococcus aureus and Acinetobacter baumannii are opportunistic pathogens, and both are involved in different oral infections. This work aimed to analyze the phytochemical composition of Myrciaria cauliflora hydroethanolic extract and to evaluate its antimicrobial and antibiofilm action against Staphylococcus aureus (ATCC 6538) and Acinetobacter baumannii (ATCC 19606; multi-resistant clinical strains 58004, 50098, 566006, and H557). Myrciaria cauliflora hydroethanolic extract was prepared, and the content of soluble solids, flavonoids, and phenols was quantified. High-performance liquid chromatography (HPLC) was performed later. The minimum inhibitory concentration was determined using the broth microdilution method according to the Clinical and Laboratory Standards Institute, standard M7-A6, and subsequently, its minimum bactericidal concentration was determined. Then, the most effective concentrations were analyzed against biofilms. Statistical analysis was performed using the ANOVA method with Tukey’s test. The soluble solids content in the prepared hydroethanolic extract of M. cauliflora was 2.22%. Additionally, the total flavonoid content, measured using the quercetin standard curve, was 0.040 mg/mL. Furthermore, the total phenol content, determined using the gallic acid standard curve, was 0.729 mg/mL. HPLC analysis presented peaks of gallic acid (11.80 m), p-coumaric acid (12.09 m), cinnamic acid derivative (19.02 m), and ellagic acid (29.83 m). The extract demonstrated antimicrobial and antibiofilm action against all tested strains. However, the most effective antibacterial concentration against all the tested bacteria was 5.55 mg/mL. Therefore, these chemical components justify that M. cauliflora hydroethanolic extract is effective in reducing biofilm formation in S. aureus (standard strain) and A. baumannii (standard and clinical strains).

Beyond the empirical pillar design method: The strain criterion and the pillar load inversion concepts

Pillar design is a crucial aspect of underground mining engineering, as it directly impacts the safety, stability, and overall effectiveness of mining operations. In this paper we present a method to calculate pillar stability based on the strain criterion and pillar load inversion concept, which complements the empirical pillar strength formulae. Those formulae do not account for certain parameters that can affect the stability of the pillars, e.g. weak layers, changes in stress orientations due to mining, orebody dip, mining layout complexity, and the influence of regional stabilizing pillars. The approach presented here is not intended to replace the empirical method; rather, we suggest using it as the initial step in the pillar design process. This should be followed by iterative numerical modelling to study pillar behaviour, define pillar stability, and optimize the pillar design by considering site-specific and representative rock mass properties and criteria.

Studies on Nigerian cashew nut shell liquid: Greening-up extraction process, chemical composition and cost effectiveness

Extractions of cashew nut shell liquid (CNSL) have always widely been carried out with non-environmentally friendly solvents. Hence, greener solvents are desired as alternative to currently used solvents. Herein, batch extractions of Nigerian CNSL with greener solvents: ethyl acetate and cyclohexane mixture in different ratios were investigated in hot and cold system and results compared with conventional solvent (petroleum ether). Compositional studies of the extracted CNSL and its isolated components were done with Fourier-Transformed Infrared (FTIR), Nuclear Magnetic Resonance (NMR) spectroscopy and Ultra High-Performance Liquid Chromatography-Mass Spectrometry (UHPLC-MS). Cost effectiveness analysis for the extraction solvents and methods was also investigated. It was revealed that ethyl acetate and ethyl acetate-cyclohexane mixture at cold and hot conditions recorded higher CNSL yields than previous reports even at a lower liquid-to-solid ratio. Chemical composition and component quantity extracted did not significantly change under hot or cold system. The present composition of the Nigerian CNSL contains unusually higher amount of anarcardic acid (79 %) and cardanol (14 %) than ever reported. Additionally, degree of unsaturation in the alkyl chain of the CNSL is in the order triene>monoene>diene in the anarcardic acid and cardanol components of the liquid. Cost effectiveness analysis at a kilogramme scale revealed that the order of greenness of extraction route based on solvent type, energy requirement and condition of extraction is ethyl acetate-solvent cold system> ethyl acetate-hot system> ethyl acetate-cyclohexane-system> cyclohexane system > pet. ether system.

Chemical Profile and In Vitro Gut Microbiota Modulation of Wild Edible Mushroom Phallus atrovolvatus Fruiting Body at Different Maturity Stages

Phallus atrovolvatus, a wild edible mushroom, has attracted increasing interest for consumption due to its unique taste and beneficial health benefits. This study determined the chemical components in the so-called fruiting body during the egg and mature stages and investigated its gut microbiota-modulating activities. The egg stage contained higher total carbohydrates, dietary fiber, glucans, ash, and fat, while the total protein content was lower than in the mature stage. Two consumption forms, including cooked mushrooms and a mushroom aqueous extract from both stages, were used in this study. An in vitro gut fermentation was performed for 24 h to assess gut microbiota regulation. All mushroom-supplemented fermentations increased short-chain fatty acid (SCFA) production compared to the blank control. Furthermore, all mushroom supplementations promoted the growth of Bifidobacterium and Streptococcus. Samples from the mature stage increased the relative abundance of Clostridium sensu stricto 1, while those from the egg stage increased the Bacteroides group. The inhibition of harmful bacteria, including Escherichia-Shigella, Klebsiella, and Veillonella, was only observed for the mature body. Our findings demonstrate that P. atrovolvatus exhibits potential benefits on gut health by promoting SCFA production and the growth of beneficial bacteria, with the mature stage demonstrating superior effects compared to the egg stage.

Using DPF to Control Particulate Matter Emissions from Ships to Ensure the Sustainable Development of the Shipping Industry

PM (particulate matter) emissions from ships are the main sources of marine atmosphere pollution. Controlling the emissions of particulate matter from ships is related to the sustainable development of the shipping industry. To reduce PM emissions from marine four-stroke diesel engines, DPFs are effective. Our results show that DPF had more than 90% capturing efficiency for both the number and mass emissions of PM, and the capturing efficiency for the accumulation mode was higher than that of the nuclear mode. DPF can also significantly reduce the chemical components of PM in marine diesel exhaust gas. The removal efficiencies for OC and EC were 89.7–91.6% and 84.8–92.8%, respectively, with each particle size range showing over 80% efficiency. SO42− was the ion with the highest content, followed by NH4+, NO3−, Na+, NO2−, and Cl−, with their reduced proportions remaining consistent with the removal efficiency of particulate matter. DPF can also effectively reduce PAH content and toxicity. The use of DPF can greatly improve the impact of ship emissions on the marine atmospheric environment. The appropriate DPF with the best performance can be selected according to the exhaust parameters and particle size distributions with different characteristics.

In-situ immobilization of ZIF-67/ZIF-8 on wood biomass for degradation of methylene blue and formaldehyde

Metal-organic frameworks (MOFs) have been extensively studied for the removal of pollutants in wastewater and air. However, the existence of MOF materials in powder form with easy agglomeration and difficult separation has greatly confined their application potential. To address this challenge, ZIF-67/ZIF-8 composites were in-situ grown on wood biomass, with its porous structure providing channels for the growth of MOFs and active sites for MOFs catalysis. The structure, i.e., morphology, crystallinity and chemical components, and optical properties were characterized. The degradation efficiency of methylene blue (MB) by the ZIF-67/ZIF-8@wood composites photocatalyst was more than 85.7 % under visible light irradiation within 90 mins, reflecting the good photocatalytic activity of the composites. The ZIF-67/ZIF-8@wood composites completely adsorbed and decomposed HCHO (22.3 ppm) within 30 mins. The high catalytic performance of the ZIF-67/ZIF-8@wood composites can be attributed to the high surface area of wood that results in a high absorption of contaminants. This simple, low-cost, and green preparation method has promoted the sustainable utilization of biomass resources with great significance for practical environmental remediation.

Unveiling the Acoustic Signature of Collichthys lucidus: Insights from X-ray Morphometry-Informed Acoustic Modeling and Empirical Analysis

Collichthys lucidus is an important small-scale economic fish species in the Yangtze River Estuary. To improve the accuracy of acoustic stock assessments for C. lucidus, it is necessary to accurately measure its target strength (TS). This study obtained precise morphological parameters of C. lucidus through X-ray scanning and established a Kirchhoff ray mode (KRM) model to simulate the changes in TS of the fish body and swimbladder at different acoustic frequencies and pitch angles. At the same time, the TS was measured using the tethered method to analyze and compare the broadband scattering characteristics obtained from both methods. An empirical formula of C. lucidus relating TS to body length at two conventional frequencies was established using the least squares method. The results show that the C. lucidus TS changes, with body length ranging from 10.91 to 16.61 cm, are significantly influenced by the pitch angle at 70 kHz and 200 kHz frequencies, and the fluctuation of TS for both the fish body and swimbladder increases with the rise in frequency. The broadband TS values estimated by the KRM model and measured by the tethered method fluctuate within in the ranges from −45 dB to −55 dB and −40 dB to −55 dB, respectively. The TS of C. lucidus tends to increase with the increase in swimbladder length. When the probability density function of the pitch angle is N(−5°, 15°), the b20 measured by the KRM and the tethered method at 70 kHz are −71.94 dB and −69.21 dB, respectively, while at 200 kHz they are −72.58 dB and −70.55 dB. This study provides a scientific basis for future acoustic target discrimination and stock assessment of C. lucidus in the Yangtze River Estuary.

Overview and limitations of database in global traditional medicines: A narrative review.

The study of traditional medicine has garnered significant interest, resulting in various research areas including chemical composition analysis, pharmacological research, clinical application, and quality control. The abundance of available data has made databases increasingly essential for researchers to manage the vast amount of information and explore new drugs. In this article we provide a comprehensive overview and summary of 182 databases that are relevant to traditional medicine research, including 73 databases for chemical component analysis, 70 for pharmacology research, and 39 for clinical application and quality control from published literature (2000-2023). The review categorizes the databases by functionality, offering detailed information on websites and capacities to facilitate easier access. Moreover, this article outlines the primary function of each database, supplemented by case studies to aid in database selection. A practical test was conducted on 68 frequently used databases using keywords and functionalities, resulting in the identification of highlighted databases. This review serves as a reference for traditional medicine researchers to choose appropriate databases and also provides insights and considerations for the function and content design of future databases.

Implications of Water Quality Index and Multivariate Statistics for Improved Environmental Regulation in the Irtysh River Basin (Kazakhstan)

The selection of sites for permanent environmental monitoring of natural water bodies should rely on corresponding source apportionment studies. Tools like the water quality index (WQI) assessment may support this objective. This study aims to analyze a decade-long dataset of measurements of 26 chemical components at 26 observation points within the Irtysh River Basin, aiming to identify priority zones for stricter environmental regulations. It was achieved through the WQI tool integrated with geoinformation systems (GISs) and multivariate statistical techniques. The findings highlighted that both upstream sections of tributaries (Oba and Bukhtarma rivers) and the mainstream of the basin are generally in good condition, with slight fluctuations observed during flooding periods. Areas in the basin experiencing significant impacts from mining and domestic wastewater treatment activities were identified. The rivers Glubochanka (GL) and Krasnoyarka (KR) consistently experienced marginal water quality throughout the observation period. Various contaminant sources were found to influence water quality. The impact of domestic wastewater treatment facilities was represented by twofold elevated concentrations of chemical oxygen demand, reaching 22.6 and 27.1 mg/L for the KR and GL rivers, respectively. Natural factors were indicated by consistent slight exceedings of recommended calcium levels at the KR and GL rivers. These exceedances were most pronounced during the cold seasons, with an average value equal to 96 mg/L. Mining operations introduced extremal concentrations of trace elements like copper, reaching 0.046–0.051 mg/L, which is higher than the threshold by 12–13 times; zinc, which peaked at 1.57–2.96 mg/L, exceeding the set limit by almost 50–100 times; and cadmium, peaking at levels surpassing 1000 times the safe limit, reaching 0.8 mg/L. The adverse impact of mining activities was evident in the Tikhaya, Ulba, and Breksa rivers, showing similar trends in trace element concentrations. Seasonal effects were also investigated. Ice cover formation during cold seasons led to oxygen depletion and the exclusion of pollutants into the stream when ice melted, worsening water quality. Conversely, flooding events led to contaminant dilution, partially improving the WQI during flood seasons. Principal component analysis and hierarchical cluster analysis indicated that local natural processes, mining activities, and domestic wastewater discharge were the predominant influences on water quality within the study area. These findings can serve as a basis for enhanced environmental regulation in light of updated ecological legislation in Kazakhstan, advocating for the establishment of a comprehensive monitoring network and the reinforcement of requirements governing contaminating activities.

Rapid identification of back-flow in three distributaries of Jingjiang Reach, middle Yangtze River, China

Unusual back-flow events occurred in 2015 and 2017 at the near-mainstream ends of the three distributaries of the Jingjiang Reach, middle Yangtze River, China. It is presently challenging to precisely quantify back-flow discharges at river distributary ends where normal-flow discharges are measured chronically. This problem is more complicated at the ends of the three Jingjiang distributaries, each of which is more than 100 km long, and thus favors the generation of different back-flow forms. We use empirical formulae based on the Saint-Venant Equation and the Fall Index Method to quantify impacts on flow discharges at the two ends of each distributary of three key hydrodynamic variables: (1) water discharge at Zhicheng hydrological station, (2) total discharge from the four southwest tributary rivers, and (3) water levels at the two ends of the distributaries. We use the variable control approach to identify the contribution ratios of natural and human driving factors to flow discharges at the two ends of the distributaries during five historical stages. The empirical formulae provide reasonable results, with high values of correlation coefficients (R2 = 0.84 ∼ 0.98) obtained, demonstrating that the total water discharge from the four southwest tributary rivers is negligible. These formulae perform well in reproducing observed flow discharges at the two ends of the distributaries, especially the maximum discharges and cumulative volumes for normal-flow and back-flow events. Three charts are devised for different flow conditions at the two ends, from which back-flow events can be rapidly identified. Before impoundment of the Three Gorges Dam (TGD), riverbed adjustment caused by the lower Jingjiang Cutoff Projects and the Gezhou Dam contributed the most to flow discharge changes (≥50 %) at the near-mainstream ends of the distributaries. Afterwards, precipitation dominated (>60 %). In the future, back-flow events are expected only to occur at Mituosi (i.e., Taipingkou) and Nanxian hydrological stations, for which optimal reservoir operation and water resource utilization could remedy the back-flow crisis. Use of climate models and more advanced technologies such as remote sensing and GIS are recommended to enhance the reliability of predictions.

Modeling simulation and output characteristic analysis of PEMFC

Abstract Facing the dual problems of environmental pollution and energy shortage, PEMFC has become a research hotspot because of its high energy conversion efficiency and non-pollution. In this paper, theoretical voltage and various loss voltages of PEMFC were analyzed in detail, and PEMFC was modeled in Simulink using an empirical formula. The influence of temperature, gas pressure, and film water content on output characteristics of PEMFC was explored by using the control variable method, and it was concluded that the parameter values of the three could be improved within a certain range. Both can improve the output characteristics of PEMFC, which provides certain reference significance for the control of PEMFC.

Seasonal variation of water-soluble inorganic ions and carbonaceous components of PM2.5 and PM1 in industrial and residential areas of Suizhou, China

Seasonal variations of fine particulate matter (PM) and its chemical components in Suizhou are investigated by collecting PM2.5 and PM1 samples from industrial and residential areas between March 2017 and February 2018. The findings reveal more severe PM pollution in industrial areas compared to residential areas. Concentrations and percentages of water-soluble inorganic ions (WSII) in PM are higher in spring and winter. Notably, the high levels of SO42− and NO3− in PM1-2.5 indicate that secondary transformation of SO2 and NOx significantly contribute to the rapid increase in PM1-2.5. The conversion of NO2 to NO3− is a key factor in the winter increase of mass concentrations of PM2.5 [ρ(PM2.5)], while photochemical reactions involving NO2 drive the summer increase of ρ(PM2.5). Organic carbon (OC) and elemental carbon (EC) are mainly distributed in PM1, with OC peaking in winter. Chemical fractionation of PM reveals that carbonaceous components have a greater impact on PM1 concentration than WSII, whereas WSII more significantly affects ρ(PM2.5) than carbonaceous components. The OC to EC ratio in industrial areas (2.5 ± 1.4) and residential areas (1.9 ± 0.8) suggests more prominent secondary aerosol pollution in industrial areas. Significant correlations between secondary organic carbon (SOC), SOC conversion rate (ηSOC), and concentrations of O3-8h and NO2 in Suizhou further indicate that O3 and NO2 levels in the atmosphere influence the generation of SOC and ηSOC.

Oxidation failure behavior and repair of the damaged SiC-ZrB2/SiC coating of C/C composites

The impacts of damage on the thermal barrier performance of SiC-ZrB2/SiC coating of C/C composites were investigated. The microstructure, chemical components, and thermal protection performance of the damaged coating before and after repair were analyzed, and the failure behavior of the damaged coated C/C composites was studied. After oxidation at 1500 °C for 360 min, the weight loss of the undamaged sample was −0.38 %, while that of the damaged sample reached 21.16 %. A repair method using polysiloxane and SiC-ZrB2 powder as repair agent was employed to recover the oxidation resistance property of the damaged coating. The repair agent generated SiOC ceramics after high-temperature treatment, covering the damaged area and bonding well with the original coating. The weight loss of the repaired sample was 2.4 %, which was significantly improved compared to the damaged coating. This work offers a research foundation for the optimization of the repair of damaged silicon-based ceramic coatings.

Rapid identification of various chemical components in Cinnamomi ramulus by UPLC-Q-Orbitrap-MS.

Cinnamomi ramulus (CR) is a common Chinese herbal medicine with a long history. It is often used to treat exogenous wind-cold diseases in clinic, but its chemical compositions remain to be studied. In this study, CR was extracted with 75% ethanol, and UPLC-Q-Orbitrap-MS combined with data post-processing method was used to identify the chemical components in the extract. Through this technology, the components in CR can be separated and accurately identified. A total of 61 compounds were identified, including 14 simple phenylpropanoids, 3 coumarins, 5 lignans, 14 flavonoids, 10 benzoic acids, 8 organic acids, and 7 others. This study confirmed the existence of these compounds in CR and speculated the cleavage pathways of each compound, which enriched the mass spectrometry data and cleavage rules. This study can provide a reference for CR and other research.

Chemical weathering and CO2 consumption rates of the Koshi River Basin: modelling and quantifying

The Koshi River is a typical river originating from the Tibetan Plateau that drains into the Indian Plain. To quantify the chemical weathering and CO2 consumption rates of the upstream alpine meltwater-supplied mountainous and downstream rainfall-impacted temperate plain regions, 46 river water samples were collected at 23 sites during monsoon and post-monsoon seasons, and major ions concentrations were measured in the laboratory. The forward model was applied to calculate carbonate weathering rate (CWR), silicate weathering rate (SWR), and their CO2 consumption rates ([CO2]car and [CO2]sil). For investigating the hydrological impacts, correlation analysis was applied between the chemical weathering rates and different runoff components based on the Spatial Process in Hydrology model at each sampling site. Results show that carbonate and silicate rock weathering control the river water chemistry. The average silicate weathering rate is 7.37 tons/km2/yr, consuming 3.40 × 105 mol/km2/yr CO2 while considering sulfide-involved carbonate weathering, the carbonate weathering rate is 26.35 tons/km2/yr, consuming 3.82 × 105 mol/km2/yr CO2. Overall, chemical weathering and CO2 consumption rates are enhanced in monsoon season in both the upstream and downstream regions owing to the intense hydrological cycle. These rates are relatively higher in the alpine upstream region during the post-monsoon season due to intense physical erosion, and higher in downstream during the monsoon season due to the greater volume of water. The significant positive correlations between snowmelt runoff with CWR and [CO2]car indicated that the rising precipitation and temperature leading to enhanced snowmelt would increase the carbonate weathering rate. Hence, this study provides a valuable understanding of the spatiotemporal variations in river hydrochemistry and the role of hydrology in shaping chemical budget within the snow and glacier-fed Himalaya River Basins.