Theoretical Basis Research Articles

The relationship between loneliness and psychological distress among Chinese college students: the mediating role of mobile phone addiction and the moderating role of core self-evaluation.

Previous studies showed that loneliness and psychological distress are related. However, the potential mechanisms involved in this relationship are unknown. This study examined the mediating effect of mobile phone addiction and the moderating effect of core self-evaluation on the relationship between mobile phone addiction and psychological distress. A total of 826 college students were recruited. A cross-sectional study design and an online questionnaire survey were employed to measure loneliness, mobile phone addiction, core self-evaluation, and psychological distress in college students, and used the PROCESS macro program to conduct moderated mediation analysis. Loneliness was significantly and positively associated with psychological distress, mobile phone addiction partially mediated the relation between Loneliness and college students' psychological distress and this indirect path was moderated by core self-evaluations. Specifically, the effect of mobile phone addiction on psychological distress was stronger for college students with lower core self-evaluations than for those with higher core self-evaluations. The results are helpful to comprehend the producing mechanism of psychological distress and provide a theoretical basis for the intervention of psychological distress.

Simultaneous dehalogenation and oxidation of dichloroacetamide by Cu-modified CoFe-LDH in three-dimensional continuous flow aerated electrocatalytic reactor

Searching for catalysts and degradation systems for synchronous dehalogenation and oxidation of haloacetamides (HAcAms) is pressing. In this study, a novel three-dimensional continuous flow aerated electrocatalytic reactor (3D CFAER) system, which employed Cu-modified CoFe layered double hydroxides (CoFe-LDH) composite/activated carbon as a catalytic particle electrode for the degradation of dichloroacetamide (DCAcAm) was constructed. Under the experiment’s optimal operating parameters, the maximum degradation rate of DCAcAm reached 91.7 %. The superior performance for the degradation of DCAcAm was due to the enhanced electron transfer induced by the modification of Cu in CoFe-LDH. Moreover, Density Functional Theory (DFT) calculations indicated that Cu doping improved the ability of LDH to dissociate water, thereby enhancing its electrocatalytic performance. Scavenger experiments and Electron Paramagnetic Resonance (EPR) results revealed that •OH, O2•– and electrochemical direct dehalogenation were responsible for DCAcAm removal. Additionally, the electrocatalytic stability of the electrode was tested upon repeated use with DCAcAm degradation remaining as high as 81.7 % after five consecutive experiments. More importantly, in 3D CFAER, electrocatalytic treatment lasting 90 min reduced the TOC and COD of the actual chlorine disinfection wastewater by 64.1 % and 74.9 %, respectively. This study provides new theoretical basis and technical support for control of HAcAms.

The chromosome-level Elaeagnus mollis genome and transcriptomes provide insights into genome evolution, glycerolipid and vitamin E biosynthesis in seeds

Elaeagnus mollis, which has seeds with high lipid and vitamin E contents, is a valuable woody oil plant with potential for utilization. Currently, the biosynthesis and regulation mechanism of glycerolipids and vitamin E are still unknown in E. mollis. Here, we present the chromosome-level reference genome of E. mollis (scaffold N50: ~40.66Mbp, genome size: ~591.48Mbp) by integrating short-read, long-read, and Hi-C sequencing platforms. A total of 36,796 protein-coding sequences, mainly located on 14 proto-chromosomes, were predicted. Additionally, two whole genome duplication (WGD) events were suggested to have occurred ~54.07 and ~35.06 million years ago (MYA), with Elaeagnaceae plants probably experiencing both WGD events. Furthermore, the long terminal retrotransposons in E. mollis were active ~0.23MYA, and one of them was inferred to insert into coding sequence of the negative regulatory lipid synthesis gene, EMF2. Through transcriptomic and metabonomic analysis, key genes contributing to the high lipid and vitamin E levels of E. mollis seeds were identified, while miRNA regulation was also considered. This comprehensive work on the E. mollis genome not only provides a solid theoretical foundation and experimental basis for the efficient utilization of seed lipids and vitamin E, but also contributes to the exploration of new genetic resources.

Effects of Scandium doping on the deuterium absorption and desorption behavior of titanium films

Understanding the effects of Scandium (Sc) on the hydrogen absorption and desorption capabilities and the underlying mechanisms within Ti–Sc alloys is crucial for their applications as hydrogen storage materials. In this study, we explore the influence of Sc on deuterium (D) behavior in Titanium (Ti) films through a combination of experimental characterization and theoretical simulations. The Sc-doped Ti films with different Sc ratio were prepared using magnetron sputtering. Our findings indicate that Sc doping raises the D absorption temperature from 350 °C to 500 °C, and the Sc-doped Ti deuteride films exhibit higher apparent activation energies and temperatures for D desorption. Results from both experiments and DFT calculations indicate that these phenomena are attributed to the atomic size effect, in which the larger Sc atoms reduce the Ti–H spacing, thereby strengthening the interaction between the adjacent Ti atoms and H atoms. The enhanced interaction presents a greater challenge for H atom diffusion within α-Ti and complicates the dissociation of TiH2. This study provides a vital theoretical and experimental basis for understanding the effects of Sc doping on the hydrogen absorption and desorption properties in titanium alloys.

Effect of microwave heating on rock damage and energy evolution

Rock fragmentation efficiency can be increased by microwave heating. The mechanical properties and energy evolution characteristics of coarse sandstone specimens under different microwave heating conditions are compared in this paper. The effects of microwave heating time and power on coarse sandstone specimens of peak stress, elastic modulus, brittleness index, damage variable, and impact energy index are analyzed. The results indicate that the microwave heating power and microwave heating time are inversely proportional to peak stress and elastic modulus and directly proportional to peak strain. With the increase of microwave heating power and microwave heating time, the brittleness index and damage variable of rock specimens increase, the impact energy index decreases. The microwave heating power and microwave heating time increase the rock brittleness index. The energy absorption rate of rock specimens decreases with the increase of microwave heating time. The impact energy index is inversely proportional to microwave heating power and microwave heating time. High-power and long-time microwave heating can reduce the possibility of rockbursts and the intensity of potential dynamic disasters. The research conclusion can provide the theoretical and technical basis for breaking rock by microwave heating.

Microstructure evolution of CdZnTe crystals irradiated by heavy ions

Consideration of irradiation effects is important for in-orbit operation and radiation protection in aerospace applications. The configuration of irradiation defects and their impact on deteriorating the carrier transport properties of CZT crystals need to be clarified. In this study, the microdefect evolution mechanism of CdZnTe (CZT) crystals under 10 MeV Chlorine (Cl) ion irradiation at flux of 1×1010∼1×1012 n·cm-2 are investigated. The stacking faults first appear in the CZT crystal at 4.5×10-4 displacement per atom (dpa), which are categorized into slip-type, gap-type and vacancy-type. In order to hinder the further expansion of stacking fault, S-shaped stacking fault dipole appears. When the dpa reaches 4.5×10-2, the local phase transition occurs in the damage zone to form CuPt-A ordered phase with ZnTe/CdTe periodic arrangement because the fluctuation in local composition and strain caused by cascade collisions. The deterioration of electric field distribution and charge collection caused by irradiation damage layer leads to the decrease of γ-ray detection ability. The energy resolution (ER) of the CZT detector for γ-ray can be maintained at 30.6% when the ion flux accumulates to 1×1012 n·cm-2, revealing high irradiation hardness. Consequently, these findings provide a theoretical basis for the radiation damage recovery of CZT detectors, further demonstrating that CZT crystals are the most competitive new generation of room-temperature nuclear radiation detection materials, and can provide radiation protection strategies for similar compound semiconductor materials.

BoMYBL2b, an R3-MYB transcription factor, inhibits anthocyanin accumulation via directly repressing BoDFR1 gene transcription in kale

Kale is a globally popular edible and ornamental plant with colorful inner leaves. Anthocyanin is one of the most major pigments for kale. However, the underlying regulatory mechanism for the accumulation of anthocyanin in kale has not been well understood to date. Here, we characterized an R3-MYB transcription factor, BoMYBL2b, whose mRNA was missing in the anthocyanin-rich kale inbred line, but abundant in the anthocyanin-less line. Knockdown of BoMYBL2b enhanced the anthocyanin accumulation. Y1H and DLR assays showed that BoMYBL2b directly inhibited the BoDFR1 gene expression by binding to the MRE sites on the ProBoDFR1. Besides, we found that BoMYBL2b did not interact with the bHLH proteins, indicating that the BoMYBL2b might not be part of the MBW complex. BoMYBL2b expression was significantly repressed by BoMYB1R1 under high light and cold stimulus, suggesting the possibility that BoMYB1R1-BoMYBL2b module might act as a cross-node for integrating light and temperature signals to regulate anthocyanin accumulation in kale. These findings provided a theoretical basis for molecular breeding of new kale cultivars and a reference for understanding the regulatory mechanism of anthocyanin accumulation in Brassica.

Proteomic analysis identified proteins that are differentially expressed in the flavonoid and carotenoid biosynthetic pathways of Camellia Nitidissima flowers

BackgroundCamellia nitidissima Chi is a popular ornamental plant because of its golden flowers, which contain flavonoids and carotenoids. To understand the regulatory mechanism of golden color formation, the metabolites of C. nitidissima petals at five different developmental stages were detected, a proteome map of petals was first constructed via tandem mass tag (TMT) analysis, and the accuracy of the sequencing data was validated via parallel reaction monitoring (PRM).ResultsNineteen color components were detected, and most of these components were carotenoids that gradually accumulated, while some metabolites were flavonoids that were gradually depleted. A total of 97,647 spectra were obtained, and 6,789 quantifiable proteins were identified. Then, 1,319 differentially expressed proteins (DEPs) were found, 55 of which belong to the flavonoid and carotenoid pathways, as revealed by pairwise comparisons of protein expression levels across the five developmental stages. Notably, most DEPs involved in the synthesis of flavonoids, such as phenylalanine ammonium lyase and 4-coumarate-CoA ligase, were downregulated during petal development, whereas DEPs involved in carotenoid synthesis, such as phytoene synthase, 1-deoxy-D-xylulose-5-phosphate synthase, and β-cyclase, tended to be upregulated. Furthermore, protein‒protein interaction (PPI) network analysis revealed that these 55 DEPs formed two distinct PPI networks closely tied to the flavonoid and carotenoid synthesis pathways. Phytoene synthase and chalcone synthase exhibited extensive interactions with numerous other proteins and displayed high connectivity within the PPI networks, suggesting their pivotal biological functions in flavonoid and carotenoid biosynthesis.ConclusionProteomic data on the flavonoid and carotenoid biosynthesis pathways were obtained, and the regulatory roles of the DEPs were analyzed, which provided a theoretical basis for further understanding the golden color formation mechanism of C. nitidissima.

Effect of anionic polyacrylamide amendment on the climatic durability of solidified waste rock fine

In order to improve the climatic durability of solidified waste rock fine (WRF), anionic polyacrylamide (APAM) was innovatively introduced to amend solidified WRF in this study. The effects of APAM content, freeze-thaw (F-T), and wet-dry (W-D) cycles on the mechanical behaviors of solidified WRF were explored. After that, zeta potential, fourier transform infrared (FTIR) spectroscopy, and scanning electron microscope (SEM) tests were initiated to understand the behavioral mechanisms of APAM. The results show that APAM can significantly improve the mechanical properties and durability of solidified WRF, and there exist a threshold content of APAM (0.3%~0.8% in this study), beyond which the strength will decrease. The microscopic test shows that the bridging effect and the filming effect induced by APAM are considered to be the two decisive factors affecting the mechanical behavior of S-WRF. On the one hand, the linear APAM long chain enables the cohesion between particles to be stronger through ion bridging, on the other hand, the long chains cross-link with each other to form a network interwoven inside the structure, thus playing a microfabric reinforcement role and enhancing the crack resistance of the solidified matrix. In addition, life cycle assessment (LCA) further confirmed the advantages of using industrial by-products combined with APAM to amend solidified-WRF. These results provide a theoretical basis for using APAM as trace additives to mitigate climatic durability-related issues.

The mechanism of supply chain efficiency in enterprise digital transformation and total factor productivity

Digital transformation (DT) represents a crucial measure for enterprises to enhance production efficiency. Supply chain construction has become a key strategic focus, and its efficient operation serves as a vital safeguard for elevating overall production efficiency within the enterprise. Based on the data of China's A-share listed enterprises from 2001 to 2022, this paper employed econometric models to investigate the impact of enterprise DT on total factor productivity (TFP),with a particular emphasis on examining the mechanistic role played by supply chain efficiency (SCE). The research findings reveal that: (1) Enterprise DT can significantly enhance TFP. The robustness of these results persists even after undergoing a series of endogeneity tests. (2) SCE plays a crucial mechanistic role in the impact of enterprise DT on TFP. The research results have been fully empirically tested, enterprises can significantly promote the inventory turnover with the help of digital technology, and then improve the TFP. The research findings and corresponding policy recommendations can provide a theoretical basis for enterprises in formulating DT strategies and delineating the supply chain development direction. This holds significant practical implications for enhancing enterprise production efficiency and achieving carbon neutral goal.

Effect of Induced Wheel and Impeller Inlet Diameter on the Hydrodynamic Performance of High-speed Centrifugal Pumps

The high-speed centrifugal pump plays a crucial role in fields such as aerospace and petrochemical industries, owing to its characteristics of elevated rotational speed and high head. During high-speed operation, the centrifugal pump is prone to cavitation, which alters the fluid flow state within the pump, leading to vibrations, noise, and a sudden decrease in pump head and efficiency. Simultaneously, the collapse of cavitation bubbles generates impact pressure that can damage the pump's internal flow components, significantly reducing its operational lifespan and causing severe consequences. Moreover, under constant-flow conditions, the absolute and relative velocities of the fluid at the impeller inlet are functions of the suction pipe diameter. Therefore, there exists an optimal value for the impeller inlet diameter to enhance the centrifugal pump's resistance to cavitation. Similarly, the different geometric and structural parameters of the inducer also influence the hydraulic performance of the centrifugal pump. The focus of this study is on the external characteristics and internal flow patterns of an optimized high-speed centrifugal pump. In this paper, the entire flow field of the model pump is numerically simulated using ANSYS CFX software. The performance and overall flow field state of the high-speed centrifugal pump under different impeller configurations and inlet diameters are explored. The influence of blade wrap angle and inlet diameter on the high-speed centrifugal pump is revealed, providing a theoretical basis for subsequent optimal design.

A novel passive method to regulate the performance of photocatalytic-Trombe wall by horizontal fins

Constrained by the inadequate percentage of ultraviolet in solar irradiation and the low transmittance of photocatalytic layer, the purification and thermal performance of photocatalytic-Trombe wall (PC-TW) need to be improved urgently. To address this, a novel passive method to regulate PC-TW performance using horizontal fins was proposed. Aiming at this innovation, by numerical method, a three dimensional model was constructed to investigate the impact of relative fins height h* and spacing s*, and the mechanism about how these parameters affect the performance was also discussed. The results indicate that: under natural ventilation strategy, compared with PC-TW without fins, the thermal efficiency ηth, purification efficiency ηHCHO and total efficiency ηtotal are improved to some extent and there exist optimal fins parameters. However, horizontal fins will instead lower the efficiencies when h* exceeds 0.4. Under forced ventilation strategy, the increase in h* contributes to all efficiencies, making ηHCHO increasing monotonically, while ηth and ηtotal present a parabolic trend. In addition, the increase in s* lowers the improved efficiencies but can still keep them in a high range. For different ventilation strategies, considering the performance and manufacturing cost, the suggested h* and s* are 0.2 and 2.5. h* and s* respectively regulate the performance by affecting the size and amount of vortex between adjacent fins, and h* has a greater impact on the performance than s*. This study not only paves a new approach for performance regulation of PC-TW, but also provides theoretical basis for structural design and operation of PC-TW with fins.

Change Patterns of Major Functional Components in the Loquat Summer Shoot Leaf during Annual Growth

Loquat leaves are widely used in traditional Chinese medicine and food processing as raw materials. To provide a theoretical basis for suitable harvesting periods based on the utilization of distinct components, the change patterns of major functional components in the annual growth of loquat leaves were investigated. In this study, the summer loquat leaves were sampled regularly during their annual growth, and the contents of seven main functional components and 13 monomer components were determined. The results showed that there was a regular change pattern for major functional components during loquat annual growth from Jul 2020 to Jun 2021; however, the change trend was different among different components. Among them, the contents of total flavonoids, total phenols, total triterpenoid acids, vitamin C, asiatic acid, quillaic acid, corosolic acid, and chlorogenic acid presented an overall upward trend. The content of maslinic acid showed a downward trend, whereas the content of neochlorogenic acid did not change much throughout the whole growth period. The content changes in the loquat leaves were affected by the light durations and temperature changes in different seasons, with mutual transit during the flowering and fruit growth processes. Sampling in May to June was found to be a most optimized option when applied in Chinese medicine processing; however, the degree of fibrosis is another indicator when it is used as food raw material. This study revealed the change pattern of major functional components of loquat leaves during the annual growth period and provides a theoretical basis for the reasonable harvesting period of loquat leaves as raw materials for processing different types of products.

Pecan-medicinal crops intercropping improved soil fertility and promoted interactions between soil microorganisms and metabolites

BackgroundPecan [Carya illinoinensis (Wangenh.) Koch] is a widely cultivated dried fruit and woody oil tree with high economic value. Continuous sole planting of pecan caused some land to lie idle and deterioration of soil conditions. Tree and medicinal crops intercropping represents an environmental-friendly and economically feasible solution to these issues. Thus, we aimed to explore the underlying mechanism by which intercropping improved soil condition by regulating the interactions of the soil microbiome and metabolome. In this study, pecans were intercropped with medicinal crops caper spurge and honeysuckle on a tree farm in China. A combined analysis of soil microbiomes and metabolomes was performed to discover the effects of intercropping on bulk and rhizosphere soils.ResultsThe results showed that intercropping improved the edaphic properties of bulk soil and promoted the growth of pecan and caper spurge. Intercropping also significantly altered the structures of both bacterial and fungal communities in bulk soil, stabilised the enrichment of nitrogen-cyclic bacteria, for instance, Bacillus, and decreased the relative abundances of plant–pathogenic fungi, for instance, Fusarium. In addition, the result of metabolomic analysis showed that intercropping promoted the synthesis of functional compounds, such as trehalose and ethanolamine, which enhanced plant disease resistance in bulk soils. Moreover, the co-occurrence networks of microbiomes and metabolomes of bulk soils revealed that Bacillus was significantly correlated with Fusarium, Alternaria, and trehalose under intercropping patterns. Furthermore, analysis of microbiomes and metabolomes in the rhizosphere soil of caper spurge and honeysuckle revealed that Penicillium and Rhizomicrobium were significantly increased by intercropping and showed more dynamic connections with other genera and metabolites compared with single planting.ConclusionsOverall, intercropping pecans with caper spurge and honeysuckle can improve soil conditions and promote plant growth through microbiological and metabolomics integrated analyses. This study provides valuable information and theoretical basis for optimizing land resource utilisation and improving soil conditions in tree fields like pecan fields via intercropping, thereby reducing production losses and ensuring economic benefits.Graphical

Vegetation greening mitigates the positive impacts of climate change on water availability in Northwest China

Climate change alters water availability (precipitation minus evapotranspiration, i.e., water yield, WY), especially in arid regions like Northwest China (NWC) where water resources are limited. Despite large-scale implementation of ecological restoration projects has contributed to greener vegetation, this may exacerbate dryland water stress, which in turn interferes with climate change impacts on WY. To better understand this issue we used the random forest model to differentiate the effects of climate change and human activities on WY. We also employed the structural equation model to explore how vegetation greening influenced climate-induced WY trends. The results showed that the multi-year average WY in NWC was 2162.21 t and demonstrated a rising trend from 1982 to 2018, primarily driven by climate change. In contrast, anthropogenic activities had minimal effects on WY but were effective in amplifying the warming and wetting effects of climate (6.64 %-7.98 %) and counteracting unfavorable climate stress effects. Vegetation greening exacerbated soil water depletion, leading to increased evapotranspiration and mitigating the positive effects of climate change on WY. Our results are crucial for an effective comprehension of the role of vegetation in regulating terrestrial water fluxes in arid regions, providing a theoretical basis for ecological restoration.

Clinical Significance of HHLA2 as a Novel Therapeutic Target for Colorectal Cancer.

Colorectal cancer (CRC) is a high-indence malignance of the digestive system with a high mortality rate in the world. The results are desired to provide an important theoretical basis for discovering new therapeutic targets for CRC. The expression of human endogenous retrovirus-H-long terminal repeat association protein 2 (HHLA2) in human CRC was detected to explore its correlationship with clinicopathological features and prognosis of patients and its potential in treating CRC. Western blot was employed to detect HHLA2 expression in fresh tissues obtained from 6 CRC patients' excisions, including cancer, paracancer, and normal issues. Immunohistochemical staining was employed to determine HHLA2 expression in paraffin-embedded specimens of 139 patients with colorectal cancer, and its relationship with the clinicopathological profiles and survival was analyzed. Small interfering RNA (siRNA) targeting HHLA2 was used to transfect CRC cells to silent HHLA2. MTT, plate colony formation, cell scratch, and Transwell assay were conducted to observe the proliferation, migration, and invasion of CRC cells. HHLA2 protein was expressed in human colorectal cancer tissues, paracancer tissues and normal tissues, which was significantly upregulated in cancer tissues (P<0.01). HHLA2 expression level in CRC tissues showed a close correlationship with the invasion depth of the tumor (P=0.000), metastasis of regional lymph nodes (P=0.018), clinical stage (P=0.010), and patient survival (P=0.011). Correlation with gender (P=0.873), age (P=0.864), location of the tumor (P=0.768), degree of tumor differentiation (P=0.569) and distant metastasis (P=0.494) exhibited no significance. The survival time of CRC patients with high and low HHLA2 expression groups was 43.231 months and 55.649 months, respectively, with a statistical difference between the two groups (P=0.001). Silencing HHLA2 inhibited proliferation, migration and invasion of CRC cells significantly. HHLA2 is overexpressed in CRC tissues which is associated with poor prognosis of patients. HHLA2 might be recognized as a new candidate for adjuvant diagnosis and prognosis of CRC, as well as a promised new target for immunotherapy of CRC.

Load-bearing characteristics of surface conductor in deepwater gas hydrate formations

The surface conductor is the first structural casing in deepwater natural gas hydrate (NGH) development, bearing the top load while suspending the casings of various layers. NGH decomposition leads to formation settlement, changing the mechanical properties of the formation and reducing the bearing capacity of the surface conductor, threatening the safety and stability of the wellhead. Understanding the bearing characteristics of the surface conductor in the hydrate formation can guide the safe drilling operation in the field. By introducing the negative skin friction theory of pile foundations and based on conventional bearing capacity models, a method for calculating the bearing capacity of surface conductors in NGH formations was developed. Using an NGH drilling simulation apparatus, the accuracy of the bearing capacity theoretical model was verified, empirical coefficients under different conditions were obtained, and the influence of soil parameters, hydrate saturation, and decomposition temperature on the bearing capacity of surface conductors was quantified. The results indicated that compared to clay, sandy soils have higher porosity and significantly weakened strength after the decomposition of NGH; when the hydrate saturation in the formation is 20%, the reduction in bearing capacity of the surface conductor in sand exceeds 30%, and in clay soils, it decreases by 25% after complete decomposition of NGH; as the hydrate saturation increases, the reduction in the bearing capacity of surface conductors after decomposition becomes more significant. Verified through Experimentation, the error of the hydrate-bearing strata-bearing capacity model is around 10%. For short-term test production operations of NGH in water, the design depth for surface conductors is around 100 meters. These research results can provide a scientific theoretical basis for the design of conductor depth below the mud， and reduce operational risks.

The source of volatile organic compounds pollution and its effect on ozone in high-altitude areas

Volatile organic compounds (VOCs) are crucial precursors in the formation of ozone (O3). The sources of pollution are complex and significantly impact O3 generation. Long-term exposure to high-concentration O3 environments causes serious damage to organisms. High-altitude areas experience continuous high temperatures and strong solar radiation, which can easily produce O3 through photochemical reactions, making these areas prone to frequent air pollution. This study utilizes the National Positioning Station of the Yinchuan Urban Ecosystem in Ningxia to conduct field synchronous observations, gathering data on VOCs, meteorological variables, and O3. By employing machine learning algorithms, we examined the seasonal distribution characteristics of VOCs, their pollution sources, and their impact on O3. The results show that the seasonal distribution of VOCs areas is low in spring and autumn and high in summer and winter. The components with higher volume fraction contribution are m-tolualdehyde in spring and summer, ethane in autumn, and acetylene in winter. The main emission sources of VOCs pollution are hydrocarbon volatile emission in spring and winter, solvent volatilization emission in summer, and industrial sources in autumn. VOCs have a negative effect on O3, with a greater impact in winter and spring, evidenced by standardized effect values of −0.26 and −0.24. The key components affecting O3 in VOCs vary by season. Aromatic hydrocarbons are the key components in spring and winter, with contribution rates of 22 % and 21.3 %. Alkenes are the key components in summer and autumn (24.5 % and 26.8 %). Among meteorological variables, temperature is the key factor affecting O3, while wind speed is the key factor affecting O3 only in winter. This study aims to clarify the sources of VOCs pollution in different seasons and their impact on O3, providing a theoretical basis and technical support for the prevention and control of VOCs and O3 pollution in high-altitude areas.

Mechanical characteristics and microscopic mechanism of polypropylene fiber modified recycled road solid waste fine aggregate mortar

Recycled fine aggregate (RFA) is a recycled building material obtained by crushing and screening waste concrete, which is the main raw material for producing recycled aggregate mortar (RAM). However, due to the defects of RFA such as many cracks, high porosity and large fragmentation index, RAM has problems such as low compressive strength and poor flexural strength, which limits its large-scale application in mortar engineering. In this paper, a series of experiments were carried out to verify that the addition of polypropylene fiber (PPF) improves the mechanical strength of RAM. Four lengths (3mm, 6mm, 9mm, 12mm) and three dosages (0.3%, 0.6%, 0.9%) of PPF were added, and their effects on the compressive strength and flexural strength of RAM were studied. The test results show that the addition of PPF can improve the compressive strength and flexural strength of RAM and increase the toughness of RAM. The addition of PPF with 0.6% dosage and 12mm length can increase the compressive strength of RAM by 57% and the residual strength by 73%. The addition of PPF with 0.9% dosage and 12mm length can increase the flexural strength of RAM by 58% and the fracture energy by 163%. Scanning electron microscopy (SEM) results show that PPF can improve the microstructure of RAM. The effective bonding between the matrix and PPF is observed, which increases the mechanical strength of RAM. In addition, PPF is pulled out and broken, proving that PPF effectively plays its bridging and stretching role in the matrix. Moreover, a prediction model for the effect of PPF length and dosage on the compressive strength and flexural strength of RAM is proposed, which can provide theoretical basis for practical engineering and reference for related researches. This study proposes a negative carbon method for applying road solid waste to engineering mortar, which can provide theoretical basis for practical engineering and reference for related research.

Fluid–rock interaction controlled by integrated hydrothermal fluid and fault: Implications for reservoir development

Hydrothermal activity is prevalent in petroliferous basins, particularly in fractured reservoirs. Hydrothermal fluids enter the reservoirs and cause significant fluid–rock interaction, which ultimately controls reservoir development. The Mahu Sag in western China is a hydrocarbon-rich region where hydrothermal fluids and faults control the reservoirs, making it challenging to understand the development mechanism of the shale reservoirs. This study focused on the Fengcheng Formation in the Mahu Sag. Based on a range of previous lithological test results, numerical models of hydrothermal fluid charging were established to explore differences in fluid–rock interactions under varying temperature, fluid, and flow rates. Results revealed that within a specific range, increasing temperature and Mg2+ concentration promoted hydrothermal processes. The hydrothermal flow rate influenced ion accumulation on the fluid-rock contact surface, thus controlling mineral dissolution rates. In a certain range, when the flow rate is increased by 3 times, the growth rate of dolomite content is increased by more than 15 times. Hydrothermal fluid flowing near the fault underwent chemical action more readily than in other areas. The influence of hydrothermal fluid and fault on reservoir development was both constructive and destructive. The decrease and increase of porosity are 30 % and 25 %, respectively. This study could provide a theoretical basis for identifying factors influencing shale reservoir development.