Water Coverage Research Articles

Effects of droplet dynamical behavior in flow channel of proton exchange membrane fuel cell under vibration conditions on cell performance

Proton exchange membrane fuel cells are subjected to severe vibration in aerospace applications. Understanding the droplet transport characteristics in the flow channelunder vibration conditions is essential for improving cell performance. However, the underlying patterns and mechanisms of the vibration effects on cell performance and its internal water transport remain unclear, and there is a lack of improvement methods for drainage under vibration conditions. This study experimentally investigates the effect of vibration on cell performance. Experimental results indicate that vibration predominantly affects cell performance through its modulation of water transport. Therefore, the droplet dynamic behavior in the flow channel is further studied using the volume of fluid method. The results indicate that vibrations can enhance the average performance of the fuel cells, with the largest increase of 8.30 %. This is attributed to vibrations promoting the detachment of droplets from the gas diffusion layer surface and reducing the water coverage ratio on said surface. Under conditions of low gas velocity, high surface hydrophobicity, and large droplet size, droplets exhibited oscillatory and jumping behavior in the flow channel due to vibration, resulting in the largest 53.5 % increase in peak water coverage ratio on the gas diffusion layer surface compared to no-vibration conditions. Furthermore, enhancing the hydrophobicity of the gas diffusion layer and the hydrophilicity of the channel walls promotes droplet detachment and discharge compared to no-vibration, as well as contributing to the improvement of vibration effects on the drainage process.

Strain Effects on the Adsorption of Water on Cerium Dioxide Surfaces and Nanoparticles: A Modeling Outlook.

Nanocrystalline ceria exhibits significant redox activity and oxygen storage capacity. Any factor affecting its morphology can tune such activities. Strain is a promising method for controlling particle morphology, whether as core@shell structures, supported nanoparticles, or nanograins in nanocrystalline ceria. A key challenge is to define routes of controlling strain to enhance the expression of more active morphologies and to maintain their shape during the lifespan of the particle. Here, we demonstrate a computational route to gain insights into the strain effects on particle morphology. We use density functional theory to predict surface composition and particle morphology of strained ceria surfaces, as a function of environmental conditions of temperature and partial pressure of water. We find that adsorbed molecular water is not sufficient to shift stability and as such under all compressive and tensile strains studied, the most stable particle is of octahedral shape, similarly to the unstrained case. When dissociative water is involved at the surfaces of the particle, then the most stable particle morphology changes under high water coverage and tensile strain to cuboidal or truncated cuboidal shapes. This shift in shape is due to strain effects that affect the strength of water adsorption.

Dust aerosol from the Aralkum Desert influences the radiation budget and atmospheric dynamics of Central Asia

Abstract. The Aralkum is a new desert created by the desiccation of the Aral Sea and is an efficient source of dust aerosol which perturbs the regional Central Asian radiation balance. COSMO–MUSCAT model simulations are used to quantify the direct radiative effects (DREs) of Aralkum dust, and investigate the associated perturbations to the atmospheric environment. Considering scenarios of “Past” (end of 20th century) and “Present” (beginning of 21st century) defined by differences in surface water coverage, it is found that in the Present scenario the simulated yearly mean net surface DRE across the Aralkum is −1.34 W m−2 with a standard deviation (±) of 6.19 W m−2, of which −0.15 ± 1.19 W m−2 comes from dust emitted by the Aralkum. In the atmosphere the yearly mean DRE is −0.62 ± 2.91 W m−2, of which −0.05 ± 0.51 W m−2 is from Aralkum dust: on the yearly timescale, Aralkum dust is cooling both at the surface and in the atmosphere, due to its optically scattering properties. The daytime surface cooling effect (solar zenith angle ≲ 70–80°) outweighs the nighttime heating effect and the atmospheric daytime (solar zenith angle ≲ 60–70°) heating and nighttime cooling effects. Instantaneous Aralkum dust DREs contribute up to −116 W m−2 of surface cooling and +54 W m−2 of atmospheric heating. Aralkum dust perturbs the surface pressure in the vicinity of the Aralkum by up to +0.76 Pa on the monthly timescale, implying a strengthening of the Siberian High in winter and a weakening of the Central Asian heat low in summer. These results highlight the impacts of anthropogenic lakebed dust on regional atmospheric environments.

Forecasting malaria dynamics based on causal relations between control interventions, climatic factors, and disease incidence in western Kenya.

Malaria remains one of the deadliest diseases worldwide, especially among young children in sub-Saharan Africa. Predictive models are necessary for effective planning and resource allocation; however, statistical models suffer from association pitfalls. In this study, we used empirical dynamic modelling (EDM) to investigate causal links between climatic factors and intervention coverage with malaria for short-term forecasting. Based on data spanning the period from 2008 to 2022, we used convergent cross-mapping (CCM) to identify suitable lags for climatic drivers and investigate their effects, interaction strength, and suitability ranges on malaria incidence. Monthly malaria cases were collected at St. Elizabeth Lwak Mission Hospital. Intervention coverage and population movement data were obtained from household surveys in Asembo, western Kenya. Daytime land surface temperature (LSTD), rainfall, relative humidity (RH), wind speed, solar radiation, crop cover, and surface water coverage were extracted from remote sensing sources. Short-term forecasting of malaria incidence was performed using state-space reconstruction. We observed causal links between climatic drivers, bed net use, and malaria incidence. LSTD lagged over the previous month; rainfall and RH lagged over the previous two months; and wind speed in the current month had the highest predictive skills. Increases in LSTD, wind speed, and bed net use negatively affected incidence, while increases in rainfall and humidity had positive effects. Interaction strengths were more pronounced at temperature, rainfall, RH, wind speed, and bed net coverage ranges of 30-35°C, 30-120 mm, 67-80%, 0.5-0.7 m/s, and above 90%, respectively. Temperature and rainfall exceeding 35°C and 180 mm, respectively, had a greater negative effect. We also observed good short-term predictive performance using the multivariable forecasting model (Pearson correlation coefficient = 0.85, root mean square error = 0.15). Our findings demonstrate the utility of CCM in establishing causal linkages between malaria incidence and both climatic and non-climatic drivers. By identifying these causal links and suitability ranges, we provide valuable information for modelling the impact of future climate scenarios.

Potentials of Green Hydrogen Production in P2G Systems Based on FPV Installations Deployed on Pit Lakes in Former Mining Sites by 2050 in Poland

Green hydrogen production is expected to play a major role in the context of the shift towards sustainable energy stipulated in the Fit for 55 package. Green hydrogen and its derivatives have the capacity to act as effective energy storage vectors, while fuel cell-powered vehicles will foster net-zero emission mobility. This study evaluates the potential of green hydrogen production in Power-to-Gas (P2G) systems operated in former mining sites where sand and gravel aggregate has been extracted from lakes and rivers under wet conditions (below the water table). The potential of hydrogen production was assessed for the selected administrative unit in Poland, the West Pomerania province. Attention is given to the legal and organisational aspects of operating mining companies to identify the sites suitable for the installation of floating photovoltaic facilities by 2050. The method relies on the use of GIS tools, which utilise geospatial data to identify potential sites for investments. Basing on the geospatial model and considering technical and organisational constraints, the schedule was developed, showing the potential availability of the site over time. Knowing the surface area of the water reservoir, the installed power of the floating photovoltaic plant, and the production capacity of the power generation facility and electrolysers, the capacity of hydrogen production in the P2G system can be evaluated. It appears that by 2050 it should be feasible to produce green fuel in the P2G system to support a fleet of city buses for two of the largest urban agglomerations in the West Pomerania province. Simulations revealed that with a water coverage ratio increase and the planned growth of green hydrogen generation, it should be feasible to produce fuel for net-zero emission urban mobility systems to power 200 buses by 2030, 550 buses by 2040, and 900 buses by 2050 (for the bus models Maxi (40 seats) and Mega (60 seats)). The results of the research can significantly contribute to the development of projects focused on the production of green hydrogen in a decentralised system. The disclosure of potential and available locations over time can be compared with competitive solutions in terms of spatial planning, environmental and societal impact, and the economics of the undertaking.

Microhabitat coverage influences avian species composition more than habitat heterogeneity in Hong Kong urban parks

The relationship between habitat heterogeneity and diversity can underpin design of urban spaces for biodiversity conservation. The area-heterogeneity trade-off hypothesis predicts that higher habitat heterogeneity should result in an increase in species richness but only up to a point, beyond which habitat micro-fragmentation leads to decreases in species diversity. However, the strength of area-heterogeneity trade-offs at small spatial scales is not well studied. We studied the relationship between avian diversity and habitat heterogeneity in 16 small urban parks across Hong Kong during the winter dry season across 2016 and 2017 (ten repeated surveys in total for each park). Habitat heterogeneity was assessed by measuring the evenness of microhabitat coverage of seven habitats as well as vertical canopy cover. In total, 12,973 individuals of 73 bird species were recorded in the study. Habitat heterogeneity had a small but negligible effect on total bird species richness or abundance. However, water coverage was positively related to total, intermediately rare and habitat specialist bird species richness, and shrub coverage was positively related to total and common bird species richness. These results demonstrate that environmental heterogeneity had little effect on avian species richness in urban green spaces at small spatial scales. We also found that microhabitat coverage can affect avian diversity and abundance, and these effects are specific to certain groups of bird species. When managing urban green spaces for biodiversity conservation in densely urbanized cities, a decrease in management disturbance (e.g. tree topping or pesticide application) will likely benefit avian species. Together with the fact that some locally uncommon species were observed throughout the study, capacity exists for environmental enhancement of these small urban parks to contribute to local avian conservation.

Carbon emission from the Lower Ob River floodplain during spring flood

Carbon emission from Arctic rivers constitutes a positive feedback between the climate warming and C cycle. However, in case of rivers with extensive floodplains, the impacts of temporary water bodies and secondary channels on CO2 exchange with atmosphere, compared to the main stem and tributaries, remain strongly understudied. In order to quantify the relative role of various water bodies of the Arctic river basin in the C cycle, the hydrochemical variables and greenhouse gases GHG concentrations and fluxes were measured within the floodplain of the largest Arctic River, Ob, in its low reaches located in the permafrost zone. These included the main stem, secondary channels, tributaries and floodplain lakes sampled over a 900 km north-south transect (25,736 km2 of the main stem and adjacent floodplain area; 7893 km2 water surface) during peak of spring flood (May 2023). In addition to main stem and tributaries, providing less than a half of overall C flux, floodplain lakes and secondary channels acted as important factor of C emission from the floodplain water surfaces. Multi-parametric statistical treatment of the data suggested two main processes of C emission from the Ob River floodplain waters: terrestrial organic matter-rich flooded wetlands (fens) provided elevated pCO2, whereas the sites of possible groundwater discharge in the secondary channels decreased the CO2 fluxes due to more alkaline environments, rich in labile metals and anionic elements.Based on available high-resolution Landsat-8 images, which matched the period of field work, it was found that the total water coverage of the floodplain during spring 2023 was 30 % of overall territory, compared to 18 % during the baseflow. Based on chamber-measured CO2 fluxes (1.56 ± 0.47 g C-CO2 m−2 d−1), overall CO2 emissions during 2 months of the spring flood from the entire Lower Ob River floodplain water surfaces including the main stem amounted to 0.73 ± 0.25 Tg C. Diffuse CH4 flux represented <1 % of total C flux. The main stem of the Ob River accounted for 34 % and 18 % of CO2 and CH4 emissions, respectively, whereas the floodplain lakes provided 59 % and 50 % of CO2 and CH4 emission, respectively. Considering that the low reaches of the Ob River represent >70 % of total river basin floodplain, and that during some years, the entire floodplain can be covered by water, emissions from the river – if assessed solely from summer (July–August) measurements – can be at least 3 times underestimated. It is therefore important to account for extended water surface during high water levels on Arctic rivers when assessing global riverine C emissions.

Implication of Urban Domestic Water Distribution on Human Health in Machakos Central Ward, Machakos County

The world's water resources are running out, and this situation is made worse by how quickly people are populating new areas, particularly in developing nations. This has highlighted the critical requirement for prepared action to manage water resources for sustainable development efficiently. Increasing water demands due to climate change, global pressures from urbanization, the already-existing unsustainable variables, and challenges of water supply systems in urban centres pose a challenge in managing water resource effectively. The purpose of the study was to investigate the implication of urban domestic water supply on human health in Machakos Central Ward, Machakos County. Using a Survey Research Design (SRD) both primary and secondary data was collected by use of questionnaires, face-to-face interviews, photography, use of GIS, authors’ observation, and the review of relevant literature in order to (1) document household water supply, (2) determine water quality for the identified categories of households and domestic water supply systems, and (3) Determine how the distribution and coverage of domestic water in a household or home affects the prevalence of water-borne illnesses. The target population was 8,331 households, from which a sample size of 381 respondents was selected. These included households, water vendors and key informants from the Machakos Water and Sewerage Company. Questionnaires (for households and vendors), interview schedules (for water officers and chiefs) and observation schedules were used as instruments for data collection. Data was analysed using Microsoft Excel and Statistical Package for Social Sciences (SPSS) software. The results revealed that the major factors attributed to lower accessibility are shortage of water, high cost of piped water connection, poor coordination, and participation of stakeholders, repairing of old and broken pipes. As a result, nearly half of the dwellers prefer to use alternative sources, exposing them to the risks of water-born diseases

Disparities in access to water, sanitation, and hygiene (WASH) services and the status of SDG-6 implementation across districts and states in India

IntroductionAccess to affordable and improved Water, Sanitation, and Hygiene (WASH) facilities is essential for people's daily lives, and it is the primary goal of Sustainable Development Goal 6 (SDG-6). However, achieving this goal is a significant challenge for many countries, including India. The aim of this study is to assess the progress made towards achieving SDG-6 targets in Indian districts, states, and Union Territories (UTs) and to identify clusters by measuring spatial inequality of WASH coverage in India. Aim and objectiveThe primary objective of this study is to measure the progress made towards achieving the SDG-6 targets for WASH facilities in Indian districts, states, and UTs. To fulfill this objective, the study used the household data of the National Family Health Survey-5 (NFHS-5) conducted from 2019 to 21. Data and methodsThe study used the household data of NFHS-5, which is a nationally representative survey that provides information on household and individual-level characteristics related to health and nutrition. The study identified the variables associated with WASH and created a composite index to measure WASH coverage separately and combined. The study used Gini coefficient to show WASH inequality, and Moran's statistics were used to show spatial dependency. ResultThe study found that the inequality of improved water coverage sources in Indian districts was high. Western and northeastern districts need to catch up in terms of achieving the SDG-6 targets. The value of the Gini coefficient (0.29) indicates that inequality in sanitation coverage is also high. All states have reached close to SDG-6 achievement in hygiene indicators. Goa, Sikkim, Andaman & Nicobar Islands, and Lakshadweep are close to the overall WASH coverage achievements of SDG-6. However, Jharkhand, Orissa, Tripura, Assam, and Rajasthan are behind in meeting the goal of SDG-6. ConclusionThe study suggests that more government initiatives and investments are needed to increase the availability, accessibility, and affordability of WASH facilities to improve WASH conditions in western and northeastern Indian districts. The localization or bottom-up approach by giving responsibility to rural and urban local bodies can also help enforce the achievement of SDG-6. The findings of this study can be used to guide policymakers in developing targeted interventions to improve WASH conditions and reduce inequality in India.

Temperature dependence of the near infrared absorption spectrum of single-wall carbon nanotubes dispersed by sodium dodecyl sulfate in aqueous solution: experiments and molecular dynamics study.

Single-wall carbon nanotubes (SWCNT) dispersed in water with the help of sodium dodecyl sulfate (SDS) surfactants exhibit a temperature dependent near infrared (NIR) exciton spectrum. Due to their biocompatibility and NIR spectrum falling within the transparent window for biological tissue, SWCNTs hold potential for sensing temperature inside cells. Here, we seek to elucidate the mechanism responsible for this temperature dependence, focusing on changes in the water coverage of the SWCNT as the surfactant structure changes with temperature. We compare optical absorption spectra in the UV-Vis-IR range and fully atomistic molecular dynamics (MD) simulations. The observed temperature dependence of the spectra for various SWCNTs may be attributed to changes in the dielectric environment and its impact on excitons. MD simulations reveal that the adsorbed SDS molecules effectively shield the SWCNT, with ~ 70% of water molecules removed from the first two adlayers; this coverage shows a modest temperature dependence. Although we are not able to directly demonstrate how this influences the NIR spectrum, this represents a potential pathway given the strong influence of the water environment on the excitons in SWCNTs. Optical absorption measurements were carried out in the UV-Vis-NIR range using a Varian Cary 5000 spectrophotometer in a temperature-controlled environment. PeakFit™ v. 4.06 was used as peak-fitting program in the spectral range 900-1400nm (890-1380meV) as a function of the temperature. Fully atomistic molecular dynamics simulations were conducted using the NAMD2 package. The CHARMM force field comprising two-body bond stretching, three-body angle deformation, four-body dihedral angle deformation, and nonbonded interactions (electrostatic and Lennard-Jones 6-16 potentials) was employed.

Quantitative analysis of spatial gene in traditional villages: a case study of Korean traditional villages in Northeast China

ABSTRACT Traditional villages possess distinct regional cultural traits and serve as a concrete manifestation and inheritance of traditional culture. In today’s era, where the preservation of traditional villages is emphasized, the study of Korean traditional villages in Northeast China, with their ethnic culture and unique spatial patterns, becomes significantly important. In this paper, we adopt the spatial gene perspective and establish a framework for analyzing spatial genes in traditional villages. Based on frequency analysis of qualitative data obtained from NVivo 14, 16 spatial gene entries were identified. Village spatial gene entries were quantified using ArcGIS, FRAGSTATS and other software. Additionally, 47 spatial gene fragments were extracted using the natural breaks method. Spatial gene sequences were mined using Spearman correlation analysis, and spatial gene maps were created. The study results indicate that: (1) the primary genes of traditional Korean villages include close to mountain, close to water, globular boundary, low integration road, etc. (2) There are significant correlations between spatial genes such as distance from mountains, mountain coverage and road integration, water coverage and boundary shape index. (3) Plain, mountain, and hill-type villages differ in characteristics such as road linear density, water coverage, and courtyard type.

Impact of greenery and waterbody on the cooling of city’s environment: a case of Rajshahi City

ABSTRACT Both plants and bodies of water are crucial to the health of the urban landscape. The degree to which these factors contribute to cooling appears, however, to change depending on factors such as location, time of year, and the mix of land use and land cover. The purpose of this study was to investigate the potential role of trees and water in Rajshahi City Corporation in reducing urban heat island effect. As a first step, satellite images are processed to generate the normalized difference vegetation index (NDVI) and the modified normalized difference water index (MNDWI). The second step is to produce maps of vegetation and water features by using a decision tree (DT) algorithm fed with threshold values from the indices. After that, thermal bands from the Landsat 8 OLI and MODIS Terra Earth observation data are used to create a map of the land surface temperature (LST). Finally, this study assessed the effect of vegetation and water coverage on global surface temperatures by analyzing their spatial distributions. Different kinds of land cover can be found in and around urban centers. Therefore, this study chose two types of water bodies (big and small) and two types of vegetation (sparse and attached/compact) for experiment. Water bodies produce cooler temperatures than other land cover types, as shown by the data. It has been found, however, that cooling rates differ across large and small bodies of water. The surface temperatures of large bodies of water are typically lower than those of smaller bodies of water. Accordingly, it appears that expansive areas significantly impact the cooling of metropolitan environments. The findings also demonstrate a difference in surface temperature between areas of dense and sparse vegetation. The cooling impact of the sparse vegetation is much less than that of the dense and widespread vegetation. There was a significant relationship between surface warming and vegetation cover in this study (R2 = 0.81). Contrarily, the presence of water and vegetation is strongly correlated (R2 = 0.88) with surface warming. The findings also show that surface warming differs depending on land use. According to a study of four typical RCC locations, business districts and industrial zones have a far greater impact on local surface temperatures than do residential developments. The experiment demonstrates that the residential area with a high proportion of vegetation had a lower average temperature by nearly 2°C. The study’s findings highlight the value of maintaining urban parks and water features.

A Combination of Remote Sensing Datasets for Coastal Marine Habitat Mapping Using Random Forest Algorithm in Pistolet Bay, Canada

Marine ecosystems serve as vital indicators of biodiversity, providing habitats for diverse flora and fauna. Canada’s extensive coastal regions encompass a rich range of marine habitats, necessitating accurate mapping techniques utilizing advanced technologies, such as remote sensing (RS). This study focused on a study area in Pistolet Bay in Newfoundland and Labrador (NL), Canada, with an area of approximately 170 km2 and depths varying between 0 and −28 m. Considering the relatively large coverage and shallow depths of water of the study area, it was decided to use airborne bathymetric Light Detection and Ranging (LiDAR) data, which used green laser pulses, to map the marine habitats in this region. Along with this LiDAR data, Remotely Operated Vehicle (ROV) footage, high-resolution multispectral drone imagery, true color Google Earth (GE) imagery, and shoreline survey data were also collected. These datasets were preprocessed and categorized into five classes of Eelgrass, Rockweed, Kelp, Other vegetation, and Non-Vegetation. A marine habitat map of the study area was generated using the features extracted from LiDAR data, such as intensity, depth, slope, and canopy height, using an object-based Random Forest (RF) algorithm. Despite multiple challenges, the resulting habitat map exhibited a commendable classification accuracy of 89%. This underscores the efficacy of the developed Artificial Intelligence (AI) model for future marine habitat mapping endeavors across the country.

Lot quality assurance sampling survey for water, sanitation and hygiene monitoring and evidence-based advocacy in Bentiu IDP camp, South Sudan.

Every year, 60% of deaths from diarrhoeal disease occur in low and middle-income countries due to inadequate water, sanitation, and hygiene. In these countries, diarrhoeal diseases are the second leading cause of death in children under five, excluding neonatal deaths. The approximately 100,000 people residing in the Bentiu Internally Displaced Population (IDP) camp in South Sudan have previously experienced water, sanitation, and hygiene outbreaks, including an ongoing Hepatitis E outbreak in 2021. This study aimed to assess the gaps in Water, Sanitation, and Hygiene (WASH), prioritise areas for intervention, and advocate for the improvement of WASH services based on the findings. A cross-sectional lot quality assurance sampling (LQAS) survey was conducted in ninety-five households to collect data on water, sanitation, and hygiene (WASH) coverage performance across five sectors. Nineteen households were allocated to each sector, referred to as supervision areas in LQAS surveys. Probability proportional to size sampling was used to determine the number of households to sample in each sector block selected using a geographic positioning system. One adult respondent, familiar with the household, was chosen to answer WASH-related questions, and one child under the age of five was selected through a lottery method to assess the prevalence of WASH-related disease morbidities in the previous two weeks. The data were collected using the KoBoCollect mobile application. Data analysis was conducted using R statistical software and a generic LQAS Excel analyser. Crude values, weighted averages, and 95% confidence intervals were calculated for each indicator. Target coverage benchmarks set by program managers and WASH guidelines were used to classify the performance of each indicator. The LQAS survey revealed that five out of 13 clean water supply indicators, eight out of 10 hygiene and sanitation indicators, and two out of four health indicators did not meet the target coverage. Regarding the clean water supply indicators, 68.9% (95% CI 60.8%-77.1%) of households reported having water available six days a week, while 37% (95% CI 27%-46%) had water containers in adequate condition. For the hygiene and sanitation indicators, 17.9% (95% CI 10.9%-24.8%) of households had handwashing points in their living area, 66.8% (95% CI 49%-84.6%) had their own jug for cleansing after defaecation, and 26.4% (95% CI 17.4%-35.3%) of households had one piece of soap. More than 40% of households wash dead bodies at funerals and wash their hands in a shared bowl. Households with sanitary facilities at an acceptable level were 22.8% (95% CI 15.6%-30.1%), while 13.2% (95% CI 6.6%-19.9%) of households had functioning handwashing points at the latrines. Over the previous two weeks, 57.9% (95% CI 49.6-69.7%) of households reported no diarrhoea, and 71.3% (95% CI 62.1%-80.6%) reported no eye infections among children under five. The camp's hygiene and sanitation situation necessitated immediate intervention to halt the hepatitis E outbreak and prevent further WASH-related outbreaks and health issues. The LQAS findings were employed to advocate for interventions addressing the WASH gaps, resulting in WASH and health actors stepping in.

Effect of high-intensity vibration parameter on droplet transport characteristics in gas channel of proton exchange membrane fuel cell

In aerospace applications, proton exchange membrane fuel cells are subject to high-intensity vibration. Vibration has a substantial effect on water transport in fuel cells. However, there is a lack of research on the effects of multi-directional and high-intensity vibration conditions on fuel cells. In this study, the droplet transport characteristics in the gas channel under high-intensity vibration conditions are investigated for the first time. Moreover, the effects of vibration direction and vibration frequency on the droplet dynamic transport process are specifically studied. The droplet transport state, drainage performance, and pressure drop variation in the gas channel under different vibration conditions are analyzed and interpreted. The results show that low-frequency vibration in the longitudinal direction is more conducive to the droplet discharge, and the pressure drop undergoes a periodic change corresponding to the vibration frequency. Vertical vibration promotes droplet detachment from the gas diffusion layer surface, which contributes to the reduction in water coverage ratio on its surface, despite an increase in the channel pressure drop. Under the influence of horizontal vibration, droplets are more susceptible to adsorption on the channel sidewalls and turn into a liquid film, which leads to a longer discharge time and a reduction in pressure drop.

Construction of ecological security pattern of arid area based on landscape ecological risk assessment: a case study of the Wu-Chang-Shi urban agglomeration.

The construction of ecological security pattern (ESP) holds paramount importance in ensuring regional environment sustainability. This study introduces an innovative approach to ESP construction grounded in landscape ecological risk (LER) assessment, with Wu-Chang-Shi urban agglomeration in Xinjiang, China, serving as a case study. Initially, LER within the area was evaluated using the LER Index (LERI) method. Subsequently, the Geodetector model was employed to discern the relationship between multi-source data and LER. Furthermore, ecological resistance and corridors were delineated utilizing the minimum cumulative resistance (MCR) model. Lastly, the corridors were optimized using the gravity model, finalizing the ESP construction. Study results reveal that LER was always fluctuating from 1990 to 2010, and tended to stabilize from 2010 to 2020. Factor detection underscores the predominant influence of land use on LER, followed by elevation and vegetation distribution. The ESP shows the imperative for improving connectivity of the natural areas that are fragmented by urban land, highlighting the great significance of the woodland-originating corridors. Finally, strategies are proposed to enhance woodland and water coverage, boost landscape diversity in nature reserves, and prioritize ecological conservation in corridor regions. In summation, the study furnishes a framework for analyzing arid regions in Eurasia. Furthermore, the research idea of evaluation-analysis-remodeling also offers insights into environmental management in developing areas with more diverse climate types.

Exogenous alpha-lipoic acid treatments reduce the oxidative damage caused by drought stress in two grapevine rootstocks.

Drought represents the predominant and most critical abiotic stress challenge within the domain of viticulture, necessitating the identification and application of efficacious strategies to ameliorate its deleterious effects. In the contemporary realm of abiotic stress management, the deployment of α-lipoic acid (α-Lipo), known for its antioxidant capabilities, as an exogenous treatment has been investigated for mitigating various abiotic stresses in numerous plant species, yet a detailed exploration of its efficacy in alleviating drought stress in grapevines remains to be conclusively determined. This study aimed to elucidate the adaptive mechanisms against drought stress by examining the effects of different α-Lipo concentrations (0, 1, 25 and 50 μM) applied on the foliar under well-irrigated and drought conditions on American grapevine rootstocks '1103 P' (drought tolerant) and '3309 C' (drought sensitive). Our findings revealed that the efficacy of α-Lipo varied significantly depending on rootstock type and irrigation status. 1103 P rootstock treated with 1 μM α-Lipo under well-irrigated conditions showed greater positive effects on growth traits, photosynthetic and osmotic parameters. In contrast, in rootstock 3309 C under the same conditions, the highest effects were obtained at 25 and 50 μM α-Lipo concentrations. Under drought stress conditions, 50 μM α-Lipo treatment improved physiological parameters (chlorophyll content, proportional water coverage and stomatal conductance), proline content and antioxidant enzyme activities (SOD, CAT and APX), while reducing electrolyte leakage and MDA levels in both rootstocks, showing a strong potential to increase oxidative stress tolerance and sustain plant growth. Heatmap visualization analysis confirmed the data obtained from Principal Component Analysis (PCA) and revealed that 1103 P treated with 50 μM α-Lipo under drought stress conditions exhibited superior physiological performance compared to 3309 C under the same conditions. This indicates the importance of potential rootstock differences in stress adaptation or α-Lipo uptake efficiency. These findings suggest that α-Lipo holds promise as an eco-friendly, natural bio-stimulant for use in arid environments, contributing to the advancement of sustainable agricultural practices in the foreseeable future.

A dataset of vector and coverage of river and lake surface water in Guangxi, Yunnan, Guizhou (China), and the ASEAN member states

Runoff plays an important role in the water cycle, and information on the distribution of rivers in a watershed is essential for water resources, ecology, environment as well as socio-economic activities in a certain region. The region involving Guangxi, Yunnan and Guizhou in China, and the ASEAN member states is known for cloudy rainfall and distinct mountainous terrain. A comparative analysis of existing river datasets highlights the insufficient characterization of river information in this unique region. To obtain more accurate river distribution data for assessing water resources and the ecological environments, we integrated in this paper the Eurasian continental river vector data (2010) and the ESA land classification data (2020). Following this, we employed an expansion and contraction buffer analysis method to address the issue of river discontinuity. And in this way, we produced a dataset of river surface water in Guangxi, Yunnan and Guizhou in China and the ASEAN member states. After further processing the ESA land classification data, we derived a vector dataset of lake surface water encompassing Guangxi, Yunnan, and Guizhou in China, along with the ASEAN member states. Finally, we calculated the coverage of river and lake surface water and compiled a coverage dataset with a resolution of 1km grid across Guangxi, Yunnan, Guizhou in China, and the ASEAN member states. Comparing with the HydroRIVERS dataset and our water remote sensing datasets (Global Surface water, Esri Land Cover, Dynamic World V1, GRWL), this dataset excels in characterizing the river system in the study area, and provides richer details than the input datasets, as evidenced by the following. This dataset can fill in gaps in the mountainous tributary sections of the Eurasian continent's river vector data from 2010, and effectively address the issue of discontinuous and missing rivers. The dataset can be used to provide basic prior data for water extraction in Guangxi, Guizhou, Yunnan and the ASEAN state members, and it holds great value in flood forecasting and water resources management. Moreover, it can also serve social and economic activities such as ecological preservation, transportation planning, agricultural irrigation and energy use.

The importance of global synchronous observation for estimating oceanic chlorophyll-a

Over the last three decades, ocean color satellites have recorded continuous change in phytoplankton concentration, and in doing so, the satellites have helped marine remote sensing to become an emerging discipline. However, ocean color satellite has provided the state of global phytoplankton only around midday whereas phytoplankton have significant diurnal variation characteristics over an entire day-night cycle, which would lead to large estimation uncertainty in downstream products. A large global field observations show that the diurnal variation curves can be constructed as the sum of an exponential and a polynomial function. After correction with our diurnal variation curves, the intermission difference between MODISA and MODIST phytoplankton product could be decreased from 7.57% to 6%, which is critical to monitor the long-term changing trend with multi-mission data. When the satellite-recorded chlorophyll-a concentration is simply equal to a daily average value, it results in overestimating uncertainties of 16% and 54% for the northern and southern hemispheric oceans, respectively. Moreover, as a typical example of downstream product of the chlorophyll-a, the coverage of oligotrophic waters can oscillate 76% from day to night simulated from satellite images with our diurnal variation curves, further confirming the importance of global synchronous observation. The geostationary satellite might be an efficient regional tool for diurnal observation, but it must account for its limitations under the weak light conditions of early morning and late afternoon. In the real world, the effects of diurnal variations in ocean properties reach far beyond chlorophyll-a in the global oceans. We anticipate these quantitatively findings to be a starting point for quantitatively re-examining the proper application of ocean color products in scientific communication.

Hydration mechanism of molybdenite affected by surface oxidation: New insights from DFT and MD simulations

The oxidation and hydration of molybdenite surfaces cannot be avoided during the crushing and flotation processes in industry, which adversely affects its clean separation and extraction. In this study, the hydration mechanism under the influence of molybdenite surface oxidation was investigated using density functional theory (DFT) and molecular dynamics (MD) simulations. The results showed that the adsorption energy of a single water molecule on the molybdenite (0 0 1) surface changed from −0.33 kcal/mol to −2.07 kcal/mol after oxidation. Dissociated O acted as a bridging link on the molybdenite (0 0 1) surface, inducing hybridization of the Hw 1 s orbitals with the Os 2p orbitals, thereby enhancing the adsorption of water molecules. The adsorption energy of a single water molecule on the molybdenite (1 1 0) surface changed from −33.97 kcal/mol to −3.37 kcal/mol after oxidation. The dissociated O hindered the hybridization of the Mo 4d and Ow 2p orbitals, thus preventing the adsorption of water molecules on the (1 1 0) surface. After oxidation, the interfacial interaction between the molybdenite (0 0 1) surface and water molecules was enhanced, while the interfacial interaction between the molybdenite (1 1 0) surface and water molecules was weakened. The water molecules near the surface of molybdenite are adsorbed through hydrogen bonding and gradually form a hydrated film consisting of three layers of water molecules with a thickness of 8–9 Å as the water coverage increases.