This study reports the use of tin oxide (SnO2) octahedral nanoparticles with exposed high-energy facets as sensing material in inkjet-printed carbon monoxide (CO) gas sensors. The nanoparticles were synthesized via a hydrothermal method aimed at encouraging high-indexed (221) crystal planes to be exposed as facets, since their high surface energy may encourage interactions with gases. Studies by X-ray diffraction (XRD) confirmed the identity of the SnO2, while transmission electron microscopy (TEM) revealed formations of octahedral-shaped SnO2 nanoparticles, with features confirming the exposure of high-energy (221) crystal facets. The nanoparticles’ reductive behavior in a CO environment was studied using temperature-programmed reduction (TPR). A stable ink based on the SnO2 nanoparticles was successfully prepared and utilized to fabricate, via inkjet printing, homogenous films onto electrically conductive graphene-based interdigitated electrodes. Optimizing the inkjet printing parameters enhanced the CO gas sensing performance of the fabricated sensors. For example, at 200 ppm, the sensor with 10 printed layers recorded a sensitivity of about 20%, as compared to a sensitivity of not more than 14% recorded in each of the sensors with 5, 15, and 20 printed layers. As a result of having homogenous films, the inkjet-printed sensors also exhibited almost double the sensitivity of similar sensors prepared by drop-casting method.

Tannery wastewater is a major environmental pollutant that introduces toxic compounds, including chromium (Cr), into agricultural soils, posing significant challenges to plant growth and productivity. This research uniquely evaluates the efficacy of three specific plant growth-promoting rhizobacteria (PGPR)—Paenibacillus polymyxa, Bacillus amyloliquefaciens, and Pseudomonas putida—for mitigating Cr stress in rice (Oryza sativa L.). In this study, O. sativa plants were exposed to different levels of tannery wastewater (0%, 50%, and 100%) in a controlled pot experiment to assess the impact of P. polymyxa, B. amyloliquefaciens and P. putida on various morpho-physio-biochemical traits. Results from the present study revealed that the Cr toxicity induced a substantial decrease in shoot length, root length, number of leaves, leaf area, shoot fresh weight, root fresh weight, shoot dry weight, root dry weight, chlorophyll-a, chlorophyll-b, total chlorophyll, carotenoid content, net photosynthesis, stomatal conductance, transpiration rate, soluble sugar, reducing sugar, non-reducing sugar contents, calcium (Ca²⁺), magnesium (Mg²⁺), iron (Fe²⁺), and phosphorus (P) contents in the plants. However, Cr stress also induced oxidative stress in the plants by increasing malondialdehyde (MDA) and hydrogen peroxide (H₂O₂), which also led to an increase in various enzymatic and nonenzymatic antioxidants and also the gene expression and sugar content. Furthermore, a significant (P < 0.05) increase in proline metabolism, the AsA–GSH cycle, and the pigmentation of cellular components was observed. Addition of P. polymyxa, B. amyloliquefaciens and P. putide into the soil significantly alleviated Cr toxicity effects on O. sativa by improving photosynthetic capacity and ultimately plant growth. Increased activities of antioxidant enzymes in organic acid and PGPRs-treated plants seem to play a role in capturing stress-induced reactive oxygen species as was evident from lower levels of MDA and H₂O₂. Moreover, the application of different PGPRs enhanced both the abundance and diversity of the rhizosphere microbiome, with bacterial population levels and Shannon diversity indices significantly increasing. A marked reduction in daily Cr intake and associated health risks was also observed under these treatments, and proteomic responses under Cr stress. Research findings, therefore, suggested that the application of PGPRs can ameliorate Cr toxicity in O. sativa seedlings and resulted in improved plant growth and composition under metal stress.

Soil contamination with toxic heavy metals such as aluminum (Al) is becoming a serious global problem due to the rapid development of the social economy. Organic acid and earthworms (Eisenia fetida) are efficient, environmentally friendly, and biodegradable and they enhance the solubility, absorption, and stability of metals. Therefore, the present study was conducted to investigate the individual and combined effects of organic chelating agents such as ascorbic acid and malic acid (5.0 µM L⁻¹ each) and earthworms (Eisenia fetida, 10 individuals per pot) on plant growth and biomass, photosynthetic pigments, gas exchange attributes, oxidative stress and response of antioxidant compounds (enzymatic and nonenzymatic), ASA–GSH cycle, cellular fractionation, and their specific gene expression, sugars, nutritional status of the plant, Al accumulation from the different parts of the plants, Al uptake, rhizosphere microbiome, health risk, and proteomic responses, in rice (Oryza sativa L. cv. IR-64) grown in soil spiked with Al [100 mg kg⁻¹ ]. Results from the present study revealed that the Al toxicity induced a substantial decrease in shoot length, root length, number of leaves, leaf area, shoot fresh weight, root fresh weight, shoot dry weight, root dry weight, chlorophyll-a, chlorophyll-b, total chlorophyll, carotenoid content, net photosynthesis, stomatal conductance, transpiration rate, soluble sugar, reducing sugar, non-reducing sugar contents, calcium (Ca^2 +)^, magnesium (Mg²⁺), iron ( Fe²⁺), and phosphorus (P) contents in the plants. However, Al stress also induced oxidative stress in the plants by increasing malondialdehyde (MDA) and hydrogen peroxide (H₂O₂), which also led to an increase in various enzymatic and non-enzymatic antioxidants and also the gene expression and sugar content. Furthermore, a significant (P < 0.05) increase in proline metabolism, the AsA–GSH cycle, and the pigmentation of cellular components was observed. Addition of organic acid and E. fetida into the soil significantly alleviated Al toxicity effects on O. sativa by improving photosynthetic capacity and ultimately plant growth. Increased activities of antioxidant enzymes in organic acid and E. fetida-treated plants seem to play a role in capturing stress-induced reactive oxygen species as was evident from lower levels of MDA and H₂O₂. Moreover, the application of organic acids and E. fetida enhanced both the abundance and diversity of the rhizosphere microbiome, with bacterial population levels and Shannon diversity indices significantly increasing. A marked reduction in daily Al intake and associated health risks was also observed under these treatments, and proteomic responses showed downregulation of HSP70, MT2A, and PRP under Al stress. Research findings, therefore, suggested that individual and combined application of organic acid and E. fetida can ameliorate Al toxicity in O. sativa seedlings and resulted in improved plant growth and composition under metal stress.

Study region

This study focuses on an arid zone of Saudi Arabia that is experiencing rapid urban growth and escalating water scarcity. The region encompasses major cities such as Mecca, Jeddah, Khulays, and Rabigh, where the demand for sustainable water resource management is becoming increasingly urgent due to the limited availability of natural freshwater sources. The challenge is further intensified by ongoing urbanization and large-scale economic developments, particularly around Mecca, Jeddah, King Abdullah Economic City, and Yanbu Industrial City, which place additional pressure on the region’s fragile water systems.

Study focus

The objective of this research is to assess and map the suitability of rainwater harvesting (RWH) sites using an integrated approach that combines Geographic Information System (GIS), the Analytic Hierarchy Process (AHP), and Multi-Criteria Decision Analysis (MCDA). The analysis incorporates hydrological, geological, and infrastructural criteria, guided by Food and Agriculture Organization (FAO) guidelines. The study also evaluates the performance and contribution of existing RWH infrastructure and identifies optimal locations for future dam construction.

New hydrological insights for the region

The results indicate that approximately 6000 km² (∼26 % of the study area) is highly suitable for RWH, with an estimated surface runoff potential of about 730 million m³ . Existing dams—Khlays, Rabiigh, and Fatima—play a significant role in regional water supply. Four primary locations—Ghoran, Thule, Qahah, and Fatima—were identified as optimal for new dam sites, with estimated water storage capacities calculated. These findings demonstrate the potential of integrated RWH planning to enhance renewable water resources, support long-term water security, and inform policy and infrastructure development in arid regions like Western Saudi Arabia.

Integrating passive and active seismic approaches is essential to yield reliable geotechnical site characterization, particularly in forthcoming industrial and/or urbanized regions. The primary objective of this study is to deliver reliable geotechnical site characterizations and address uncertainty-related repeatability of different techniques to derive S-wave velocity structures (). We employed three comprehensive field survey measurements, including 10 shallow P-wave refraction tomography profiles, 10 multi-channel analyses of surface waves (MASW) profiles, and 20 horizontal-to-vertical spectral ratios of microtremor (MHVSR) measurements. These measurements were carried out on the forthcoming industrial zone in Aswan, Egypt. We newly introduced a straightforward approach based on the allowable bearing capacity () and the local geological information to examine the resulting uncertainty.

Thus, we addressed the repeatability of different techniques to derive the  using MASW and MHVSR. The  based on MHVSR-derived  considered as the safest lower boundary. Consequently, the criticism of MASW and MHVSR inversion uncertainty is addressed for the future-planned low-rise buildings in the forthcoming industrial zone in Aswan, Egypt. The derived seismic vulnerability index () exhibits very high, high, and low categories. The NS and EW directional MHVSRs are transverse to the EW and NS main strikes of the seismogenic active fault system, respectively. There is a remarkable correlation between  and the time-averaged S-wave velocity of the upper 30 m () derived from MHVSR. Finally, we found that high densities, empirically calculated based on P-wave velocity, correlate well with the high-gravity anomalies observed in the southern portion of the study area.

This study presents the first integrated geographic and predictive modeling assessment of Hofmeister ions in groundwater and their potential link to chronic kidney disease of unknown etiology (CKDu) in South Sinai, Egypt. A total of 25 groundwater samples were collected from Wadi Feiran and Wadi El Sheikh and analyzed for major ions, nutrients, and key physicochemical parameters. The results revealed alarmingly high levels of nitrate (mean = 478.1 ppm) and total dissolved solids (TDS, mean = 2093 ppm), far exceeding World Health Organization (WHO) safety standards, and pointing to substantial potential risks to public health in these arid communities. Although the weighted arithmetic Water Quality Index (WQI) classified all samples as “good” to “excellent,” detailed hydrochemical assessment showed that concentrations of Hofmeister ions—particularly calcium and sodium—surpassed safe average daily intake thresholds in many samples (21 and 16, respectively). Such exceedances raise concerns over the potential development of hypercalcemia, hypertension, and the progression of CKDu, particularly among populations with limited access to alternative drinking water sources. Hydrochemical interpretations suggest that rock–water interactions, evaporation, and anthropogenic inputs are likely contributors to the observed ion levels. Predictive modeling using multiple linear regression (MLR) demonstrated excellent performance (R² = 99.71 % for nitrate), highlighting its value in forecasting contamination trends and identifying groundwater vulnerability hotspots in data-scarce arid regions. These findings underscore the urgent need for targeted groundwater quality monitoring, the integration of predictive risk modeling into management frameworks, and the implementation of preventive public health measures. By bridging geochemical data with health risk metrics, this research provides a scientific basis for developing evidence-based policies to safeguard communities and promote the sustainable use of groundwater resources in arid environments.

Morelia City stands in central México, within the Trans-Mexican Volcanic Belt and the Michoacán-Guanajuato volcanic field. With a population of about 850,000, it is the largest and most populated city in the state of Michoacán. In 1991, UNESCO designated its historic center as a World Heritage Site, attracting millions of tourists yearly. However, the city is vulnerable to regional intraplate and inter-plate earthquakes and the municipality’s outdated building regulations. Recently, the strong shaking experienced in the metropolitan area due to the November 19th, 2022 (Mw7.7) subduction earthquake on November 19th, 2022 (Mw 7.7), emphasizes the need to understand the site's effects and to update the municipality’s building regulations. This study presents a comprehensive seismic microzonation of Morelia, using the ambient noise horizontal-to-vertical spectral ratio (HV) technique as an initial step toward mitigating seismic risk. Because of several peaks in the HV, we presented the HV amplification at several frequencies and not only at the dominant frequency, as is usually the case. We identified amplification levels of up to 6.0. We also inverted the HVs, considering the thicknesses identified by geological data, to create a velocity model of the subsurface extending to a depth of 400 m. The results indicate the existence of a local half-graben where the sediment thickness ranges from 50 to 110 m and define the regions with the most significant amplification. Furthermore, we reported the existence of long-period ground vibrations that could affect high-rise buildings, long-span bridges, and historical buildings. Since HV ambient noise amplification maps do not always effectively predict earthquake responses, we also compared these maps with acceleration maps from two recorded earthquakes at similar frequencies. One of these earthquakes was a subduction event, while the other originated from a local source. They exhibited low and high central frequency sources, respectively, as recorded by the accelerograph network of the Universidad Michoacana. The excellent correspondence between all the output results indicates the reliability of the used approach.