共检索到 66

An analytical methodology was developed for the first time in this work enabling the simultaneous enantiomeric separation of the fungicide fenpropidin and its acid metabolite by Capillary Electrophoresis. A dual cyclodextrin system consisting of 4 % (w/v) captisol with 10 mM methyl-beta-cyclodextrin was employed in a 100 mM sodium acetate buffer at pH 4.0. Optimal experimental conditions (temperature 25 degrees C, separation voltage -25 kV, and hydrodynamic injection of 50 mbar x 10 s) allowed the simultaneous separation of the four enantiomers in <10.7 min with resolutions of 3.1 (fenpropidin) and 3.2 (its acid metabolite). Analytical characteristics of the method were evaluated and found adequate for the quantification of both chiral compounds with a linearity range from 0.75 to 70 mg L-1, good accuracy (trueness included 100 % recovery, precision with RSD<6 %), and limits of detection and quantification of 0.25 and 0.75 mg L-1, respectively, for the four enantiomers. No significant differences were found between the concentrations determined and labelled of fenpropidin in a commercial agrochemical formulation. The stability over time (0-42 days) of fenpropidin enantiomers using the commercial agrochemical formulation was evaluated in two sugar beet soils, revealing to be stable at any time in one sample, while in the other a decrease of 45 % was observed after 42 days. Individual and combined toxicity of fenpropidin and its metabolite was determined for the first time for marine organism Vibrio fischeri, demonstrating higher damage caused by parent compound. Synergistics and antagonists' interactions were observed at low and high effects levels of contaminants.

期刊论文 2025-12-01 DOI: 10.1016/j.talanta.2025.128233 ISSN: 0039-9140

The aerosol scattering phase function (ASPF), a crucial element of aerosol optical properties, is pivotal for radiative forcing calculations and aerosol remote sensing detection. Current detection methods for the ASPF include multi-sensor detection, single-sensor rotational detection and imaging detection. However, these methods face challenges in achieving high-resolution full-angle measurement, particularly for small forward (i.e., less than 10 degrees) or backward (i.e., more than 170 degrees) scattering angles in open path. In this work, a full-angle ASPF detection system based on the multi-field-of-view Scheimpflug lidar technique has been proposed and demonstrated. A 450 nm continuous-wave semiconductor laser was utilized as the light source and four CMOS image sensors were employed as detectors. To detect the full-angle ASPF, four receiving units capture angular scattering signals across different angle ranges, namely 0 degrees-20 degrees, 10 degrees-96 degrees, 84 degrees-170 degrees, 160 degrees-180 degrees, respectively. The influence of the relative illumination and angular response of the used image sensors have been corrected, and a signal stitching algorithm was developed to obtain a complete 0-180 degrees angular scattering signal. Atmospheric measurements have been conducted by employing the full-angle ASPF detection system in open path. The experimental results of the ASPF have been compared with the AERONET data from the Socheongcho station and simulated ASPF based on the typical aerosol models in mainland China, showing excellent agreement. The promising results demonstrated in this work have shown a great potential for detecting the full-angle ASPF in open path.

期刊论文 2025-12-01 DOI: 10.1016/j.optlastec.2025.113386 ISSN: 0030-3992

The presence of exotic species of plants in a region is associated with anthropogenic activities due to their economic and commercial benefits. When these exotic species hinder the development of native species, they are considered invasive. In Brazil, two species stand out: Pinus spp. and Eucalyptus spp. Their presence within ecosystems may result in environmental imbalances caused by allelopathy. The allelochemicals released by these invasive species can enter the environment through rainfall, decomposition of plant material, root exudation, and volatilization. The high solubility of phenolic compounds produced by these plants allows them to reach water bodies and potentially affect aquatic organisms. In light of this, a toxicological evaluation was conducted by exposing Daphnia magna, Aliivibrio fischeri, Landoltia punctata, and Lactuca sativa seeds to soil elutriates from areas with exotic and native vegetation. The samples were collected in close proximity, with the primary difference being the type of vegetation cover. Upon characterization, the soil covered by native species was found to contain higher levels of organic matter and moisture, whereas the soil with exotic species appeared drier. Overall, the toxicological evaluation revealed that elutriates from native vegetation induced greater toxic effects on the aquatic organisms D. magna and A. fischeri. Conversely, elutriates from exotic vegetation showed lower concentrations of total phenolic compounds but still exhibited toxic effects on the development of L. sativa seeds and caused notable structural damage to the aquatic macrophyte L. punctata.. This study highlights the importance of investigating reforested areas dominated by exotic species to better understand the potential environmental impacts caused by invasive plants.

期刊论文 2025-09-01 DOI: 10.1016/j.actao.2025.104085 ISSN: 1146-609X

Tree architecture is an important component of forest community dynamics - taller trees with larger crowns often outcompete their neighbors, but they are generally at higher risk of wind-induced damage. Yet, we know little about wind impacts on tree architecture in natural forest settings, especially in complex tropical forests. Here, we use airborne light detection and ranging (LiDAR) and 30 yr of forest inventory data in Puerto Rico to ask whether and how chronic winds alter tree architecture. We randomly sampled 124 canopy individuals of four dominant tree species (n = 22-39). For each individual, we measured slenderness (height/stem diameter) and crown area (m2) and evaluated whether exposure to chronic winds impacted architecture after accounting for topography (curvature, elevation, slope, and soil wetness) and neighborhood variables (crowding and previous hurricane damage). We then estimated the mechanical wind vulnerability of trees. Three of four species grew significantly shorter (2-4 m) and had smaller crown areas in sites exposed to chronic winds. A short-lived pioneer species, by contrast, showed no evidence of wind-induced changes. We found that three species' architectural acclimation to chronic winds resulted in reduced vulnerability. Our findings demonstrate that exposure to chronic, nonstorm winds can lead to architectural changes in tropical trees, reducing height and crown areas. La arquitectura de los & aacute;rboles es un componente importante de la din & aacute;mica de la comunidad forestal: los & aacute;rboles m & aacute;s altos con copas m & aacute;s grandes suelen sobrepasar a sus vecinos, pero por lo general corren m & aacute;s riesgo de sufrir da & ntilde;os inducidos por el viento. Sin embargo, es poco lo que se sabe sobre el impacto del viento en la arquitectura de los & aacute;rboles en entornos forestales naturales, sobre todo en bosques tropicales complejos. En este caso, utilizamos LiDAR y 30 a & ntilde;os de datos de campo en Puerto Rico para preguntarnos si los vientos cr & oacute;nicos alteran la arquitectura de los & aacute;rboles. Se tom & oacute; una muestra aleatoria de 124 individuos del dosel de cuatro especies arb & oacute;reas dominantes (n = 22-39). De cada individuo, medimos la esbeltez (altura/di & aacute;metro) y el & aacute;rea de la copa (m2) y evaluamos si la exposici & oacute;n a vientos cr & oacute;nicos influ & iacute;a en la arquitectura teniendo en cuenta la topograf & iacute;a (curvatura, elevaci & oacute;n, pendiente, humedad del suelo) y las variables del vecindario (aglomeraci & oacute;n y da & ntilde;os previos por huracanes). Luego, estimamos la vulnerabilidad mec & aacute;nica de los & aacute;rboles al viento. En los lugares expuestos a vientos cr & oacute;nicos, tres de las cuatro especies crecieron mucho menos (2-4 m) y tuvieron & aacute;reas de copa m & aacute;s peque & ntilde;as. Cecropia schreberiana, en cambio, no mostr & oacute; indicios de cambios inducidos por el viento. La aclimataci & oacute;n arquitect & oacute;nica de tres especies a los vientos cr & oacute;nicos llevaba a una reducci & oacute;n de la vulnerabilidad. Nuestros hallazgos demuestran que la exposici & oacute;n a vientos cr & oacute;nicos puede provocar cambios arquitect & oacute;nicos en los & aacute;rboles tropicales, reduciendo su altura y la superficie de sus copas.

期刊论文 2025-06-12 DOI: 10.1111/nph.70294 ISSN: 0028-646X

This study investigates the underlying causes of pier displacement and cracking in a highway link bridge. The initial geological assessment ruled out slope instability as a contributing factor to pier movement. Subsequently, a comprehensive analysis, integrating in situ soil investigation and finite element modeling, was conducted to evaluate the influence of additional fill loads on the piers. The findings reveal that the additional filled soil loads were the primary driver of pier tilting and lateral displacement, leading to a significant risk of cracking, particularly in the mid- of the piers. Following the removal of the filled soil, visual inspection of the piers confirmed the development of circumferential cracks on the columns of Pier 7, with the crack distribution closely aligning with the high-risk zones predicted by the finite element analysis. To address the observed damage and residual displacement, a reinforcement strategy combining column strengthening and alignment correction was proposed and validated through load-bearing capacity calculations. This study not only provides a scientific basis for analyzing the causes of accidents and bridge reinforcement but, more importantly, it provides a systematic method for analyzing the impact of additional filled soil loads on bridge piers, offering guidance for accident analysis and risk assessment in similar engineering projects.

期刊论文 2025-06-02 DOI: 10.3390/buildings15111929

In high-mountain contexts, rainfall can trigger various flow-like mass movements, from debris flows to hyperconcentrated flows and flash floods. Despite similar runout and velocity, propagation mechanisms are different. In such complex phenomena, also the existing protection structures play a fundamental role. In this paper, a multi-phase mathematical framework is adopted to simulate the propagation of a mixture of soil and water along a 3D terrain model. The mass and momentum conservation equations are solved including the rheological behavior models for the materials involved: frictional for soil, Newtonian for water. Some selected scenarios are discussed for a site-specific case study in Northern Italy. The controversial role played by two storage basins located at the toe of the gully is explored numerically and compared to the field evidence. The novelty of the paper is to show how the water temporarily impounded in the basins enhanced the mobility of an incoming debris flow, which turned into an hyperconcentrated flow and went out of the protections structure.

期刊论文 2025-05-01 DOI: 10.1007/s10064-025-04268-1 ISSN: 1435-9529

Soil thermal conductivity (STC) plays a crucial role in regulating the energy distribution of both the surface and underground soil layers. It is widely applied in various fields, including engineering design, geothermal resource development and climate change research. A rapid and accurate estimation of STC remains a key focus in the study of soil thermodynamic parameters. However, the methods for estimating STC and their distinct characteristics have yet to be systematically reviewed. In this study, we used bibliometrics to comprehensively and systematically review the literature on STC, focusing on knowledge graph characteristics to analyze the development trend of calculation schemes. The main conclusions drawn from the study are as follows: (1) In recent years, most studies have been focused on soil thermal characteristics and their main contributing factors, the soil hydrothermal process in the Qinghai-Tibet Plateau, geothermal equipment and numerical simulations, and the exploration of geothermal resources. (2) A systematic review of various schemes indicates that no single scheme is universally applicable to all soil types. Moreover, a single parameterization scheme fails to meet the practical requirements of land surface process models. We evaluated the advantages and disadvantages of the traditional heat conduction schemes, parameterization schemes, and machine learning-based schemes and the findings suggest that a comprehensive scheme that integrates these three different schemes for STC simulations should be urgently developed.

期刊论文 2025-05-01 DOI: 10.1007/s00704-025-05483-2 ISSN: 0177-798X

Numerous endorheic lakes in the Qinghai-Tibet Plateau (QTP) have shown a dramatic increase in total area since 1996. These expanding lakes are mainly located in the interior regions of the QTP, where permafrost is widely distributed. Despite significant permafrost degradation due to global warming, the impact of permafrost thawing on lake evolution in QTP has been underexplored. This study investigated the permafrost degradation and its correlation with lake area increase by selecting four lake basins (Selin Co, Nam Co, Zhari Namco, and Dangqiong Co) in QTP for analysis. Fluid-heat-ice coupled numerical models were conducted on the aquifer cross-sections in these four lake basins, to simulate permafrost thawing driven by rising surface temperatures, and calculate the subsequent changes in groundwater discharge into the lakes. The contribution of these changes to lake storage, which is proportional to lake area, was investigated. Numerical simulation indicates that from 1982 to 2011, permafrost degradation remained consistent across the four basins. During this period, the active layer thickness first increased, then decreased, and partially transformed into talik, with depths reaching up to 25 m. By 2011, groundwater discharge had significantly risen, exceeding 2.9 times the initial discharge in 1988 across all basins. This increased discharge now constitutes up to 17.67 % of the total lake water inflow (Selin Co). The dynamic lake water budget further suggests that groundwater contributed significantly to lake area expansion, particularly since 2000. These findings highlight the importance of considering permafrost thawing as a crucial factor in understanding the dynamics of lake systems in the QTP in the context of climate change.

期刊论文 2025-04-01 DOI: 10.1016/j.jhydrol.2024.132529 ISSN: 0022-1694

Desertification is a global environmental issue that significantly threatens ecosystem stability and vegetation restoration in arid regions. This study proposes a multiple treatment strategy combining Artemisia sphaerocephala Krasch. gum (ASKG) with Enzyme-Induced Carbonate Precipitation (EICP) to enhance wind erosion control and seed germination. The effects of this approach were evaluated through field experiments. The results showed that single EICP treatment improved soil water retention and surface strength. However, high-concentration EICP treatment (>= 0.2 mol/L Cementation Solution, CS) induced salt stress, which suppressed plant survival. In contrast, when low-concentration EICP (0.1 mol/L CS) was combined with ASKG, a stable crust formed, improving surface strength and crust thickness, while preventing damage to the crust during early plant growth. The addition of 1.0 g/L ASKG reduced wind erosion depth by 67%, increased average moisture content to 7.4%, and promoted better seed germination, showing strong ecological compatibility and long-term stability. Furthermore, the second EICP treatment optimized the soil pore structure by adding CaCO3 precipitates, which increased average moisture content to 10.6% and increased surface strength by 114.5%. Microstructural analysis revealed that ASKG formed film or mesh structure around CaCO3 crystals, enhancing soil wind erosion resistance and water retention. Overall, the findings suggest that the multiple treatment strategy of EICP combined with ASKG successfully overcomes the ecological limitations of traditional high-concentration EICP, providing a sustainable solution for wind erosion control and vegetation restoration in desert areas.

期刊论文 2025-03-20 DOI: 10.1002/ldr.5589 ISSN: 1085-3278

This paper is based on the construction of the underground Pile-Beam-Arch station at Beitaipingzhuang Station of Beijing Metro Line 12. It employs finite element software for three-dimensional numerical modeling, faithfully reproducing the entire station construction process. The results indicate that the excavation of the pilot tunnel and the stage of the secondary lining buckle arch are the main causes of surface deformation. Additionally, the construction of the secondary lining buckle arch is the primary factor inducing deformation in the middle column and side pile. On this basis, the paper investigates the influence of four crucial factors: the stagger distance of the pilot tunnel excavation, the sequence of the secondary lining buckle arch, the excavation sequence of the lower soil, and the excavation depth on the stress and deformation characteristics of the stratum and the station structure. The results suggest that when the distance between adjacent pilot tunnel faces is 1.5 to 3 times the diameter of the pilot tunnel, it has the greatest influence on surface settlement. When the first side is followed by the middle, closely aligning the second lining with the initial support, and simultaneously installing buckle arches on both sides minimizes deformation of the stratum and station structure. During excavation of the lower soil in the station, reducing the single excavation depth and prioritizing excavation on both sides help control deformation of the vertical bearing structure. The optimal construction scheme is derived through multi-criteria optimization and implemented in the field. Field monitoring results are in good agreement with simulation outcomes, offering valuable reference for the construction of stations under similar geological conditions.

期刊论文 2025-03-13 DOI: 10.1038/s41598-025-92929-2 ISSN: 2045-2322
  • 首页
  • 1
  • 2
  • 3
  • 4
  • 5
  • 6
  • 7
  • 末页
  • 跳转
当前展示1-10条  共66条,7页