Changes In Composition Research Articles

Predictive modeling of ash and moisture content in acid-treated walnut shells using artificial neural networks

ABSTRACT In this paper, the use of artificial neural networks (ANN) to predict changes in ash and moisture content (MC) of walnut shells after acidic pretreatment was investigated. The physicochemical and structural properties of walnut shells were analyzed, as well as the influential parameters on the changes of these studied variables. The study aimed to determine the changes in the walnut shells composition and evaluate the possibility of using the ANN model to predict the above-mentioned initial variables. The ANN model showed extremely high performance in modeling, with a coefficient of determination (R2) of 0.99 for ash and 0.90 for MC and low values of root mean square error (RMSE) and χ2, indicating the accuracy of the model in predicting the composition of walnut shells after acidic pretreatment. This study confirms the potential of ANN in accurately modeling changes in the composition of walnut shells and paves the way for further research on a wider range of crops and different pretreatments.

Rhizosphere microecological mechanism of carbon sequestration and its emission mitigation in rice ratooning

Rice ratooning plays a critical role in mitigating global climate change and enhancing soil carbon sequestration due to its properties of carbon fixation and emission reduction. The rhizosphere micro-ecosystem emerges as one of the key determinants, thus it is highly significant to investigate the impact changes in rhizosphere microbial composition on the ecological mechanisms associated with carbon sequestration and emission reduction in paddy fields. Over two consecutive years, this study analyzed greenhouse gas emission characteristics, photosynthetic carbon assimilation patterns, and rhizosphere microenvironmental differences between the main crop (MC) and ratoon season rice (RSR) using four rice varieties with distinct growth stages and genetic traits. The results demonstrated that compared to MC, RSR reduced the daily average methane (CH₄) emissions from paddy field by 57.78∼64.31 %, while decreasing the distribution of photosynthetic products to the rhizosphere soil by 78.15 %. 16S rRNA sequencing revealed a significant increase in the abundance of autotrophic microorganisms, and the carbon-fixing bacterium Pseudarthrobacter was isolated and identified in RSR soil. The exogenous addition of this microorganism increased the soil organic carbon (SOC) content of RSR by 4.65 %, while simultaneously reducing CH₄ emissions from paddy fields by 26.25 %. The significant increase in autotrophic carbon-fixing bacteria in the rhizosphere soil is one of the key micro-ecological mechanisms driving carbon sequestration and emission reduction in paddy fields. This is attributed to the reduced allocation of photosynthetic carbon assimilation products to the belowground components, thereby promoting the abundance of autotrophic carbon-fixing bacteria in RSR field. Consequently, the ecological niche width of heterotrophic microorganisms, such as methanogens, is reduced, while autotrophic carbon-fixing bacteria mitigate greenhouse gas emissions from RSR field by fixing CO₂ and increasing SOC content. The findings offer valuable theoretical and practical perspectives on attaining the overarching objectives of carbon neutrality and food security.

Effect of Uremic Toxins and Methoxy-PEO Chain Density on Plasma Protein Adsorption.

Protein adsorption can direct the host response to blood-contacting biomaterials. Poly(ethylene oxide) (PEO) is commonly employed to minimize nonspecific protein adsorption. Although chain density has been observed to play a role in the inherent resistance of protein adsorption by end-tethered films of PEO, only a few papers correlate the change in PEO chain densities with the adsorbed plasma protein composition. Almost all studies rely upon blood from healthy patients for these studies even though they are applied to the unhealthy. In the case of patients with kidney failure, there is a remarkable change in the blood composition due to retained metabolites. In the pursuit of personalized dialysis, we must address this dearth in the literature regarding the effect of metabolite accumulation in the blood compartment on the adsorption of protein to blood-contacting biomaterials. To this end, surface films of different methoxy-PEO (mPEO) chain densities were used to evaluate the changes in adsorbed proteins in the presence of uremic metabolites (i.e., uremic toxins). End-tethered mPEO films were characterized using contact angles, ellipsometry, and X-ray photoelectron spectroscopy. Plasma protein adsorption was conducted with and without uremic toxins commonly found in patients with end stage kidney disease, and the adsorbed protein profile was identified using immunoblots. It was found that the presence of uremic toxins led to a notable increase in the adsorption of almost all of the proteins. It was evident that while chain density plays a role in overall protein resistance, the effect of uremic toxins led to substantial increases in adsorbed proteins and needs to be considered when designing next-generation blood-contacting materials.

Defining the extracellular matrix in non-cartilage soft-tissues in osteoarthritis: a systematic review.

Extracellular matrix (ECM) is a critical determinant of tissue mechanobiology, yet remains poorly characterized in joint tissues beyond cartilage in osteoarthritis (OA). This review aimed to define the composition and architecture of non-cartilage soft joint tissue structural ECM in human OA, and to compare the changes observed in humans with those seen in animal models of the disease. A systematic search strategy, devised using relevant matrix, tissue, and disease nomenclature, was run through the MEDLINE, Embase, and Scopus databases. Demographic, clinical, and biological data were extracted from eligible studies. Bias analysis was performed. A total of 161 studies were included, which covered capsule, ligaments, meniscus, skeletal muscle, synovium, and tendon in both humans and animals, and fat pad and intervertebral disc in humans only. These studies covered a wide variety of ECM features, including individual ECM components (i.e. collagens, proteoglycans, and glycoproteins), ECM architecture (i.e. collagen fibre organization and diameter), and viscoelastic properties (i.e. elastic and compressive modulus). Some ECM changes, notably calcification and the loss of collagen fibre organization, have been extensively studied across osteoarthritic tissues. However, most ECM features were only studied by one or a few papers in each tissue. When comparisons were possible, the results from animal experiments largely concurred with those from human studies, although some findings were contradictory. Changes in ECM composition and architecture occur throughout non-cartilage soft tissues in the osteoarthritic joint, but most of these remain poorly defined due to the low number of studies and lack of healthy comparator groups.

Problems and challenges of lichen inventory in a changing environment: The case of the “Mszar” and “Redykajny” reserves in Olsztyn

The paper presents the state of knowledge of the lichen biota of the “Mszar” and “Redykajny” nature reserves, located in the “Las Miejski” urban forest complex in Olsztyn (north-eastern Poland). The results of the inventory conducted in 2024 are described, which are compared with published data collected in 1999–2001. So far, a total of 118 lichenized and three non-lichenized fungi have been identified in this area. Recent studies did not confirm the occurrence of 18 species, but at the same time showed 32 species new to the study area. The article discusses possible causes of changes in the species composition of the lichen biota over almost 25 years and the effectiveness of various methods of collecting data in the field. The results prove that both reserves are still important refuges of forest lichen biodiversity on a scale larger than just the area of Olsztyn’s urban forests.

Influence of gut bile acid composition on the glucose‐lowering effect and safety of metformin

AimsThis study evaluates how changes in intestinal bile acid composition, induced by cholestyramine, a bile acid sequestrant, affect metformin's pharmacodynamics (PD).MethodsAn open‐label, 2‐period 1‐sequence crossover study was conducted with healthy male adults. Each period consisted of both before and after metformin treatments. Cholestyramine was administered during the second period to change the bile acid pool. For, PD assessment, an oral glucose tolerance test was conducted at each treatment in both periods. Metformin was administered 3 times during each period, and cholestyramine was administered 3 times per day for 7 days during the second period. Maximum serum glucose concentration, area under the glucose concentration curve and homeostatic model assessment of insulin resistance were calculated. Baseline‐corrected PD parameters were derived by subtracting pre‐metformin values from post‐metformin values. Lipid and panels and bile acid profiles in stool were measured. Adverse events were monitored throughout the study.ResultsFourteen subjects completed the study. The mean values of 3 PD parameters were all decreased after metformin administration in both periods. Cholestyramine administration led to a further decrease in baseline‐corrected PD parameters, significantly reducing the area under the glucose concentration curve by 44.7%. Diarrhoea, the most common adverse event, was reported in 10 subjects during the metformin alone treatment and in 1 subject during the cholestyramine combined treatment (P < .01).ConclusionCholestyramine affected the glucose‐lowering effect of metformin by the possible change in the bile acid pool in the gut, and metformin‐associated diarrhoea was improved by cholestyramine.

Assessment of the effectiveness of overseeding methods for hardwood meadows under various pluviothermal conditions

The aim of this study is to evaluate the effects of improving the state of hardwood meadows using two methods of overseeding: strip-till and disc seeding (Vredo), with mixtures of grass and legume seeds under diverse pluvial and thermal conditions in eastern and central Poland. The field experiments were conducted in three farms: Zimna Woda (experiment I), Racibory (experiment II), and Ranna (experiment III). The measures to improve permanent grassland (PG) were carried out after the second cut in 2016 and in spring 2017. The effectiveness of both methods was evaluated based on changes in the botanical composition of the sward and the yield of total protein and soluble sugars (Preś and Rogalski, 1997). Positive effects of both methods on the floristic composition were achieved in 2017 in all meadow habitats on mineral soils: brown soils formed from loamy sand (Zimna Woda), proper brown soils (Racibory) on light and medium loam, and alluvial soils on light loam (Ranna). Despite adverse pluvial and thermal conditions, both methods improved the utility value of the sward, increasing the yields of dry matter, protein, and soluble sugars in subsequent years. The study showed that improving the state of PG by overseeding with diploid and tetraploid grass varieties and legume plants is effective, with its level of effectiveness depending on the pluvial and thermal conditions after treatment.

Rainfall and Soil Moisture Jointly Drive Differences in Plant Community Composition in Desert Riparian Forests of Northwest China

Extreme rainfall and soil moisture play important roles in the survival, community composition, and ecosystem function of desert plants. This study focused on arid desert riparian forests ecosystems in the Ebinur Lake Basin of Xinjiang, China. We analyzed the effects of rainfall and soil moisture on species composition, indicator species, β diversity, species turnover, and nestedness using three consecutive years of community surveys. A zero-model combined with a Bayesian framework was used to explore the response of species turnover and nestedness to soil moisture and rainfall, and variance decomposition was used to quantify the relative importance of spatial distance, rainfall, and soil factors in determining species composition. The results indicated the following: (1) when rainfall was high, the richness and abundance of annual herbaceous plants increased. The proportion of the community based on richness (32%) and abundance (58.1%) of annual herbaceous plants in 2016 was higher than that in 2015 and 2017. The Jaccard, Bray–Curtis, and Chao indexes of the community in years with higher rainfall were significantly higher than in years with lower rainfall; however, a lag effect was also observed. (2) Soil factors explained 5% of the changes in community composition, rainfall explained 12% of the changes in community composition, and spatial distance, soil factors, and rainfall jointly explained 32% of the changes in community composition. (3) We also showed that high soil moisture leads to greater β diversity than low soil moisture. Rainfall had the greatest explanatory power on the measured values of β diversity (19.6%) and species turnover (38%), and the factor with the greatest explanatory power for species nestedness was the interaction between rainfall and soil moisture (26.2%). Our findings indicate that drought and rainfall drive differences in plant community composition, with rainfall playing a dominant role. These results provide a basis for understanding the impact of extreme rainfall events on arid ecosystem functions.

High-temperature (800 °C) performance of spodumene slag-based ternary sulphate composite phase change materials with improved mechanical property

The large deployment of electric vehicles leads to decarbonised road transport. However, the mining and smelting of lithium resources will continue to increase, which generates lithium slag and urgently needs to be recycled. The integration of spodumene slag with ternary sulphate presents a green and promising approach to achieve resource recycling and high-performance composite phase change material (CPCM). Herein, toughened and strengthened CPCMs are prepared by the hybrid sintering method with mechanical properties better than reinterned glass, even after high-temperature thermal cycling. After the cold compression and hot sintering process, the production of colloidal sodium silicate bonds the ternary sulphate with the spodumene slag skeleton, which greatly enhances the strength of the CPCM for efficient and durable thermal energy storage (TES). The Hydroxyl polar group of sodium silicate interacts with the skeleton and leads to a record-breaking compressive strength of 155.23 MPa, and the CPCM can support its stacking of 23.6 m and 15 kg loading test at 700 °C. A negligible mass loss of 0.26 wt% was observed after 50 thermal cycles at 800 °C. Moreover, the CPCMs exhibit a high TES density of up to 873.0 J/g in the temperature range of 100–800 °C. High charging and round-trip efficiency in the heat recovery process from spodumene roasting is also achieved, as it is 5 % and 19 % higher than the common magnesium bricks, respectively. The CPCM achieves high thermal efficiency TES, and it is the effective resource recycling of lithium slag with simple material preparation, which, from two angles at once, attacks the carbon emission from the life cycle of the lithium-ion battery.

Tribo-oxidation mechanism of gradient nanostructured Inconel 625 alloy during high-temperature wear

The tribo-oxidation layer is typically formed at the contact interface of high temperature wear, which exhibits a significant effect on the friction behavior of gradient nanostructured (GNS) materials. This study systematically investigated the wear resistance, near-surface microstructure, and compositional changes of ultra-thick GNS Inconel 625 alloy subjected to surface mechanical rolling treatment (SMRT) under high-temperature sliding wear conditions. The experimental results indicated that as the temperature increased to 500 °C, a tribo-oxidation layer was formed on the surface of the GNS sample, thereby resulting in an abnormal increase in the coefficient of friction (COF) and a rapid decrease in the wear rate. The gradient nanostructures facilitated oxidation diffusion channels, promoting the formation of a protective Cr2O3 film and spinel oxides, reducing the wear rate. At lower temperatures, a rapidly formed Cr2O3 film shielded the matrix, forming a tribo-oxidation layer composed of Cr2O3 and nickel. At 800 °C, the tribo-oxidation layer exhibited complex structures, including glaze, spinel oxide, Cr2O3, and Cr2O3/Ni mixed layers. This complexity was attributable to the oxidation diffusion rate of the gradient nanostructures and tribo-oxide layers. The findings not only elucidated the tribo-oxidation mechanism of GNS nickel-based superalloys but also offered valuable insights for designing wear-resistant materials.

Whole mount preparation and analysis of rabbit mammary gland

The mammary gland undergoes dynamic structural and compositional changes throughout life, influenced significantly by hormonal fluctuations and environmental factors. From embryonic development through menopause, this tissue adapts to accommodate phases such as postnatal expansion, pregnancy-induced lactation, and post-weaning involution. Hormones, growth factors, cytokines, and exogenous factors regulate these innate processes, affecting mammary epithelial cell proliferation and sensitivity, particularly in terminal end buds (TEB) and lobules, which are highly susceptible to endocrine disruption. Rodent models have provided invaluable insights into mammary gland biology, yet differences exist compared to human development, prompting the exploration of alternative models like rabbits. Additionally, there is momentum to move away from the use of nonhuman primates in safety assessments, increasing the need for evaluation tools for all tissues in the rabbit model. Rabbit mammary glands exhibit similarities to humans, making them promising for studying breast biology and pathology. However, protocols for whole-mount analysis of rabbit mammary glands are lacking due to the technical challenges of working with thicker tissue than rodent mammary glands. Here, we developed a methodology modified from rodent studies for preparing and analyzing rabbit mammary gland whole mounts, which is essential for advancing research in mammary gland biology and understanding the effects of hormonal and toxicant-induced disruption of mammary gland growth and function.

Short-term continuous cropping leads to a decline in rhizosphere soil fertility by modulating the perilla root exudates

Continuous cropping obstacles are a prevalent issue in agricultural production worldwide. However, the key factors leading to these obstacles differ among various crops. This study utilized high-throughput sequencing and metabolomics to assess the community structure of microbes and the types and abundance of metabolites in rhizosphere soil after different continuous cropping years of Perilla frutescens L. Britt. (perilla). The results indicate that differential metabolites in soils of varying continuous cropping years are primarily associated with pathways for cellular lipid formation, oxidative stress responses, and energy metabolism. These findings suggest that the changes in soil composition over time are linked to specific biological processes related to lipid formation, oxidative stress, and energy metabolism. The relative abundance of beneficial bacteria in the soil, such as Sphingomonas, Gemmatimonas, and Blastococcus, decreased significantly (p < 0.05), while harmful fungi, such as Neocosmospora and Didymella, increased in response to the increase in continuous cropping years (p < 0.05). The symbiotic network between bacteria and fungi has become less dense and stable after continuous cropping. Enzymatic activities in rhizosphere soil decreased significantly (p < 0.05). Soil organic matter, total nitrogen, total phosphorus, total potassium, available phosphorus, and available potassium declined significantly (p < 0.05). Pearson correlation analysis identified 10 differential secondary metabolites that were closely related to the relative abundance of key microorganisms. Among them, cinnamic acid and flavonoid compounds are key factors leading to changes in microbial diversity, and they can regulate the microorganisms-soil- plants interactions. In summary, this study provides a novel scientific explanation for how continuous cropping can reduce soil fertility and a theoretical basis for subsequent cultivation strategies of perilla.

Drug-Resistant Epilepsy and Gut-Brain Axis: an Overview of a New Strategy for Treatment.

Drug-resistant epilepsy (DRE), also known as intractable epilepsy or refractory epilepsy, is a disease state with long-term poorly controlled seizures attack. Without effective treatment, patients are at an elevated risk of injury, premature death, mental disorders, and poor quality of life, increasing the need for a fresh perspective on the etiology and treatment of DRE. The gut is known to harbor a wide variety of microorganisms that can regulate the host's response to exogenous signals and participate in various physiological and pathological processes in the human body. Interestingly, emerging evidence has uncovered the changes in gut microbiota in patients with epilepsy, particularly those with DRE. In addition, both dietary interventions and specific antibiotic therapy have been proven to be effective in restoring the microecological environment and, more importantly, reducing seizures. Here, we reviewed recent studies on DRE and the involvement of gut microbiota in it, describing changes in the gut microflora composition in patients with DRE and corresponding animal models. Furthermore, the influence of the ketogenic diet, probiotics, fecal microbiota transplantation (FMT), and antibiotics as microbiome-related factors on seizure control and its possible mechanisms are broadly discussed. Finally, we highlighted the significance of gut microbiome in DRE, in order to provide a new prospect for early identification and individualized treatment of patients with DRE.

ERICH4 is not involved in the assembly and secretion of intestinal lipoproteins

Background and AimsThe small intestine plays a central role in lipid metabolism, most notably the uptake of dietary fats that are packaged into chylomicrons and secreted into the circulation for utilisation by peripheral tissues. While microsomal triglyceride transfer protein (MTP) is known to play a key role in this pathway, the intracellular assembly, trafficking, and secretion of chylomicrons is incompletely understood. Methods and ResultsUsing human transcriptome datasets to find genes co-regulated with MTTP, we identified ERICH4 as a top hit. The gene encodes for glutamate-rich protein 4, a protein of unknown function. REACTOME gene-function prediction tools indicated that ERICH4 is involved in intestinal lipid metabolism. In addition, GWAS data point to a strong relationship between ERICH4 and plasma lipids. To validate ERICH4 as a lipid gene, we generated whole-body Erich4 knockout (Erich4-/-) mice. ERICH4 deficiency, however, did not result in changes in body weight and composition, food intake, circulating plasma lipids, energy absorption and excretion, and tissue weights compared to controls. Additionally, there were no morphological abnormalities seen in the small intestine. Challenging mice with a high-fat diet did not give rise to a phenotype either. ConclusionsDespite prediction tools indicating ERICH4 as a strong candidate gene in intestinal lipid metabolism, we here show that ERICH4 does not play a role in intestinal lipid metabolism in mice. It remains to be established whether ERICH4 plays a role in human lipid metabolism.

Characterization of the soybean oil body interface: revealing the mechanism of changes in the interfacial protein composition, structure, and function of oil bodies extracted under different denaturation conditions

We investigated the stability and rheological properties of extracts from soybean oil bodies (OB) obtained under different denaturing conditions (heating, guanidine hydrochloride, urea, and sodium dodecyl sulfate (SDS)). Differences in the interfacial and antioxidant properties exhibited by the different compositions of interfacial proteins in the extracted OB were also assessed. SDS disrupted the interfacial structure of OB, whereas the treatments under the other three denaturing conditions effectively increased the ability of the OB proteins to form a network structure. The analysis of the secondary and tertiary structures of proteins showed that all denaturation conditions affected both hydrogen bonding and hydrophobic interactions of the protein molecules, with urea leading to the most pronounced structural unfolding and rearrangement of the OB proteins. The microstructure results of the protein indicated that the protein treated with GuHCl and urea exhibited a 'shell-like' structure and structural decomposition, which can promote the pre-encapsulation of active substances through hydrogen bonding or hydrophobic interactions. The electrophoretic results further confirmed that SDS could displace 24-kDa proteins and disrupt the original membrane structure of OB, whereas urea removed most of the extrinsic proteins. The interfacial proteins extracted from OB using the four denaturing methods were different but all had enhanced interfacial and antioxidant properties compared to the control. Therefore, the extraction of OB under different denaturation conditions facilitated the hierarchical extraction of its interfacial proteins, thereby broadening its application in the food industry.

A Call for a Different Plant Modelling Paradigm and a New Generation of Software

This paper is an invitation to change the plant modeling paradigm to achieve much easier convergence and ensure model consistency between different incarnations of the plant model, while retaining accuracy on par with the rigorous models. Rigorous physical properties [property/mole] are replaced by [property/mass] approximation at local conditions, making bulk properties much less sensitive to changes in stream composition. This eliminates the need for stream mole fractions and stream compositions can be described by linear component mass flows. Detailed process flow diagram is a common topology for all models. Different incarnations of node models are employed at different levels of abstraction (planning, scheduling, optimization, control, design), ensuring inheritance, consistency and increasing accuracy of solutions as plant model instances move from mass to mass-energy, to mass-energy-and-approximate-stream-properties. After the plant model with approximate properties is solved, they are updated via rigorous thermodynamic methods and the plant model is resolved until convergence.

Microbiome shifts elicited by ornamental lighting of granite facades identified by MinION sequencing

Night-time outdoor illumination in combination with natural sunlight can influence the visible phototrophic colonizers (mainly algae) growing on stone facades; however, the effects on the microbiome (invisible to the naked eye) are not clear. The presence of stone-dwelling microbes, such as bacteria, diatoms, fungi, viruses and archaea, drives further biological colonization, which may exacerbate the biodeterioration of substrates. Considering the microbiome is therefore important for conservation of the built heritage. The impact of the following types of lighting on the relative abundance and diversity of the microbiome on granite ashlars was evaluated in a year-long outdoor pilot study: no lighting; lighting with a metal halide lamp (a traditional lighting system currently used to illuminate monuments); and lighting with a novel LED lamp (an environmentally sound prototype lamp with a biostatic effect, halting biological colonization by phototrophs, currently under trial). Culturable fractions of microbiome and whole-genome sequencing by metabarcoding with Oxford Nanopore Sequencing (MinION) was conducted for bacteria and fungi in order to complement both community characterization strategies. In addition, the possible biodeteriorative profiles of the isolated strains, relative to calcium carbonate precipitation/solubilisation and iron oxidation/reduction, were investigated by plate assays. Alpha and beta diversity indexes were also determined, along with the abundance of biocide and antibiotic resistance genes. Culture-dependent microbiological analysis failed to properly show changes in community composition, for which metagenomic approaches like MinION are better suited. Thus, MinION analysis identified shifts in the granite microbiome elicited by ornamental lighting. The novel LED lamp with the biostatic effect on phototrophs caused an increase in the diversity of bacteria and fungi. In this case, the microbiome was more similar to that in the unlit samples. In the samples illuminated by the metal halide lamp, dominance of bacteria was favoured and the presence of fungi was negligible.

Ecological indicators for restoration success: Development of fish diversity in a large restored floodplain over twelve years

The restoration of rivers and their floodplains is complex, requires substantial financial efforts, intensive stakeholder involvement and long recovery times, making the identification of appropriate ecological indicators for restoration success a key challenge. Herein, one of the largest floodplain restorations along the European Danube was repeatedly assessed over a 12-year period. Changes in the fish community composition in relation to chemical and morphological habitat variables were assessed in all three restored habitat types free-flowing rivers (RS), reconnected oxbows (OS), and small floodplain ponds (FP) which are only temporarily connected to the main stem Danube. Fish species composition of RS, OS, FP and the Danube differed significantly. Species numbers (34 detected in 2022) remained largely constant since the last monitoring in 2013, whereas abundance increased by 15%. Small-bodied target species with short generation times were able to establish populations comprising all size classes shortly after restoration, whilst large-bodied species needed a decade after the restoration for full demographic representation. Highly specialised species such as the rheophilic Chondrostoma nasus used restored RS only during the life stages spawning and juvenile growth. Restoration increased habitat heterogeneity and the initialized hydromorphological processes are still ongoing, supporting the high species diversity. The observed differences in colonization patterns can be explained by species-specific life histories, resulting in diverse short and long-term responses of different fish species and life stages following restoration. Consequently, a comprehensive assessment of restoration success only becomes possible if multiple fish species as ecological indicators are combined in a long-term monitoring.

Decadal changes in summer aerosol composition and secondary aerosol formation mechanisms in Beijing

Abstract Aerosol chemistry in China has undergone significant transformation due to stringent emission control measures, leading to great shifts in aerosol composition and formation mechanisms. This study investigates the summer chemical evolution of aerosol species in Beijing over the past decade based on two summertime measurements using aerosol chemical speciation monitors. The results reveal a substantial decrease in fine particulate matter concentrations by 72.7% in summer over the past decade, particularly primary species that dropped by 86.3-95.1%. However, this improvement in particulate matter was accompanied by a worsening of ozone pollution between 2011 and 2022. In contrast, secondary components such as sulfate and secondary organic aerosol (SOA) exhibited significant increases in their contributions, rising from 18.2-25.5% to 21.4-41%. The varying responses of aerosol species to emission reductions are closely tie to changes in emission sources, aerosol chemistry, and meteorology. By decoupling the influence of meteorology through machine learning, our analysis highlights the crucial role of emission reductions in improving air quality, though with different impacts on aerosol chemistry. The dominant formation mechanisms of secondary components varied between the two summers, likely influenced by shifts in aerosol liquid water content and atmospheric oxidation capacity due to NOx reductions. Compared to the summer of 2011, the formation of sulfate and SOA in summer 2022 was primarily driven by photochemical processes related to ozone, with less impacts from aqueous-phase formation, while nitrate was predominantly formed via N2O5 heterogeneous hydrolysis. Considering the complex nature of secondary aerosol formation, future summer pollution control strategies should prioritize stricter collaborative regulation of precursors for both secondary aerosol and ozone.

Study the Structural and Optical Properties (Energy Gap) of Polythiophene/MWCNT/SnO2 Nanocomposite as an NO2 Gas Sensor

The polythiophene (PTh) is of great interest in various applications due to its unique electrical, mechanical and structural. In this work, PTh was synthesized using the oxidation method by employing ferric chloride (FeCl3) as an oxidizing agent, Then the nanocomposite polythiophene: Multi walled carbon nanotubes: Tin (IV) oxide (PTh/MWCNT/SnO2) was prepared by adding constant weight ratio of MWCNT(0.7g) and different weight ratios of SnO2 (0.1, and 0.5g) using the oxidation method. The FE-SEM images of the pure PTh and the nanocomposite showed an apparent change in the morphological composition of the surface. The X-ray diffraction (XRD) pattern of PTh/ MWCNT/SnO2 nanocomposites show the appearance of clear peaks for SnO2, while there are broad peaks for MWCNT. As for the polymer, its behavior is random. The morphology of these nanocomposites shows that the nanotubes were not well aligned and were randomly entangled. The Fourier transformer infrared (FT-IR) spectra of the pure and nanocomposite samples prepared by chemical method in the range of 450-4000 cm-1 wave number are recognized the chemical pledges (bonds) as well as functional groups in the compound. The band gap energy decreased from 3.53 into 2.78 and 2.97 when SnO2 was added. The sensitivity of the two nanocomposites shows a good enhancement 14.6% and 62% at temperature 150oC as gas sensor.