Search Results (72)

In this study, the stationary chloride permeability of ordinary Portland cement mortar exposed to salt fog–dry cycles is investigated. An original salt fog–dry cycling test setup, comprising an outer upstream tank and four inner downstream reservoirs, is established to explore chloride transport behavior through the bulk material. Steady-state chloride flux is discovered from the chloride profile, which exhibits a linear concentration gradient in both the convection and diffusion zones, following months of salt fog–dry cycles. Based on experimental observations, this study proposes a double-broken-line model to mathematically represent the chloride profile. An equivalent diffusion zone is then proposed by considering the deposited convection factor. Correspondingly, the diffusion coefficient of the equivalent diffusion zone is determined using Fick’s first law. Considering the effects of water-to-cement ratio and fog temperature, the stationary chloride permeabilities range from 0.283 × 10⁻¹² m²/s to 0.674 × 10⁻¹² m²/s, which are generally consistent with field data for concrete exposed to salt aerosols/dry environments. Although chloride permeability is temperature-dependent and, to some degree, affected by mixture proportion, the researchers recognize the aggregate/sample size effect on the variance of diffusivity values. Recommendations are drawn to upgrade the chloride transport scenario for a reliable evaluation of coarse-sand mortar and concrete. Full article

Background: Long-term care facility (LTCF) residents are highly susceptible to healthcare-associated infections, and prevention is challenging given frailty, dementia, communal living, and resource constraints. Environmental surface and air contamination contribute to transmission. Novel no-touch automated disinfection technologies have been studied in hospitals, but evidence specific to LTCFs is scarce. This scoping review summarizes recent LTCF-focused interventions, their effectiveness, and implementation considerations. Methods: This scoping review was conducted following the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) Checklist. We searched PubMed, Medline, Embase, CINAHL, and Scopus for observational or experimental studies evaluating environmental disinfection in LTCFs/nursing homes, excluding body decolonization, non-LTCF settings, and reviews/protocols. Two reviewers independently screened and extracted data via Covidence. This review has been registered on OSF (Open Science Framework). Results: Of 1491 records, 7 studies met the inclusion criteria (6 from the USA, 1 from Australia): one cluster randomized trial, one interrupted time series studies, three prospective observational studies, and two pre–post designs. Interventions included physical methods (HVAC-integrated UV/UVGI, continuous UVGI) and chemical approaches (dry hydrogen peroxide, room fogging plus chlorine dioxide wipes, hydrogen peroxide wipes). Outcomes were heterogeneous (surface SARS-CoV-2 RNA, COVID-19 attack/case rates, airborne/surface microbial loads, and one clinical endpoint—acute respiratory illness). Several studies reported reductions in environmental or airborne bioburden; however, UV-based studies did not demonstrate statistically significant reductions in clinical infections. Certainty was limited by small numbers, non-randomized designs, and diverse outcome measures. Conclusions: No-touch automated disinfection methods appear promising as supplements to standard infection prevention control bundles for reducing environmental contamination in LTCFs. Nevertheless, consistent clinical benefits are unproven. Rigorous, LTCF-tailored, adequately powered trials with standardized clinical and environmental outcomes, plus implementation and cost-effectiveness evaluations, are needed. Full article

Fog-dependent Tillandsia landbeckii in the hyper-arid Atacama Desert lacks the red-edge reflectance pattern that supports vegetation monitoring, motivating shortwave infrared (SWIR) approaches. We evaluated a newly developed UAV-borne multispectral SWIR camera system for estimating plant water status and additional plant functional traits (fresh and dry biomass, and N uptake) from four spectral bands (1100, 1200, 1510, and 1650 nm) across 20 destructively sampled plots. Of five traits tested, only canopy water content (CWC) retained statistically robust spectral associations after multiple-testing correction, with most significant predictors concentrated in the 1200–1510 nm wavelength region. A physically interpretable predictor, the mean spectral slope between 1200 and 1510 nm, yielded conditional cross-validated $R_{\mathrm{cv}}^2=0.51$ (${\mathrm{RMSE}}_{\mathrm{cv}}\approx 170$ g m⁻²), though fully selection-corrected estimates were substantially lower ($R_{\mathrm{cv}}^2=0.10$–$0.20$), reflecting feature-selection instability at the given sample size. The absence of robust biomass- and nitrogen-related signals is physically interpretable given the species’ atypical surface optics. While expanded sampling and independent validation remain necessary to establish transferable performance estimates, these results demonstrate that SWIR-based water-status retrieval is feasible for this spectrally challenging species, opening a pathway toward functional monitoring of fog-dependent desert ecosystems. Full article

Approaches, methods, and corresponding ground-based and air/space-borne instrumentation currently utilized for detecting, studying, and monitoring fogs (including in situ and remote sensing techniques) are summarized. Special attention is paid to the existing and some emerging methods enabling reliable assessments and quantification of basic fog parameters, such as visibility, liquid water content, droplet number/volume concentration, effective radius, and size distribution. Along with purely natural fogs and those resulting directly or indirectly from industrial, combustive, or other human activities (smog, chemical fogs), entirely artificially created fogs are also subject to consideration in this study. Systems and apparatuses for the generation and control of artificial fogs are presented and discussed in terms of operational principles, design, and applicability. Methods and devices for fog water collection/harvesting are presented in view of their importance for solving the lack of water problem in dry and desert regions. Some other actual and potential applications of natural and artificial fogs are summarized and discussed related to air freshening or cleaning from chemicals and radioactive aerosols, fire extinguishing, nebulized therapies in medicine, spray coating of tablets or material surfaces, aeroponic agriculture, dust-proof coatings, etc. Full article

Soiling is one of the main performance risks for bifacial photovoltaic (PV) technology, particularly in arid environments such as the Atacama Desert, where dust is deposited asymmetrically on the front and rear surfaces of the modules. This study evaluates one year (July 2022 to June 2023) of soiling behavior in bifacial modules installed in fixed-tilt and horizontal single-axis tracking (HSAT) configurations, enabling a comparison to be made between static and moving structures. The average dust accumulation was found to be 0.33 mg/cm² on the front surface and 0.15 mg/cm² on the rear surface of the fixed modules. In contrast, the respective values for the HSAT systems were found to be lower at 0.25 mg/cm² and 0.035 mg/cm². These differences resulted in performance losses of 5.8% for fixed modules and 3.7% for HSAT systems. Microstructural analysis revealed that wetting and drying cycles had formed dense, cemented layers on the front surface of fixed modules, whereas tracking modules exhibited looser deposits. Natural cleaning events, such as fog, dew and frost, only provided partial and temporary mitigation. These findings demonstrate that bifaciality introduces differentiated soiling dynamics between the front and rear surfaces, emphasizing the importance of tailored cleaning strategies and the integration of monitoring systems that consider bifacial gain as a key operational parameter. These insights are crucial for developing predictive models and cost-effective O&M strategies in large-scale bifacial PV deployments under desert conditions. Full article

Recent climatic extremes, characterized by hot and dry summers, threaten grape yield and berry composition, increasing the need for sustainable mitigation strategies. In this study, a fruit-zone cooling system was tested to reduce sunburn damage and improve vine performance. The system integrates proximal sensors and an automatic misting actuator, triggered when the air temperature exceeds 35 °C. Over two seasons (2022–2023), trials were conducted on Pignoletto vines subjected to four treatments: control (C), misted without defoliation (C + FOG), defoliated (DEF), and defoliated plus misted (DEF + FOG). The effects on microclimate, yield, berry sunburn, and berry composition were evaluated. Misting consistently reduced both air and berry temperature. Treated vines showed increased yield, mainly due to reduced sunburn and higher cluster weight. Although no clear differences in technological maturity were observed, misted vines tended to retain higher acidity under extreme heat. Flavonol synthesis was unaffected by cooling but stimulated by increased light exposure, being higher in defoliated vines. Volatile compounds analysis highlighted misting’s moderating effect on oxidative stress and aroma profile shifts, particularly during the hotter season. Overall, the cooling system proved effective in mitigating summer stress, offering a promising tool for preserving yield and berry composition in white cultivars under climate change. Full article

The continuous demand for uninterrupted super-fast wireless communication services can only be fulfilled by transmitting electromagnetic waves at high frequencies. This study investigates the impacts of atmospheric visibility on Free Space Optical (FSO) Communication links operating at three Near-Infrared (NIR) frequencies, 353 THz (850 nm), 273 THz (1100 nm), and 194 THz (1550 nm), in some selected business-hub cities (Ikeja, Calabar, Abuja and Kano) in Nigeria. Fifteen years (2009–2023) of visibility data retrieved from the archive of the National Oceanic and Atmospheric Administration (NOAA) were utilized to investigate the impacts of seasonal visibility on fog-induced specific attenuation. Kernel density estimation (KDE) was used to estimate and categorize seasonal visibility as low-visibility (LV) and high-visibility (HV) during wet and dry seasons. The triangular kernel provides the best estimation across all the stations with lowest Integrated Square Errors (ISEs). Similar seasonal trends were observed for the computed fog-induced specific attenuations at the selected wavelengths. Specific attenuation shows double peaks noticed in LV dry and LV wet seasons. Maximum specific attenuations of about 0.27 dB/km, 0.22 dB/km, 0.23 dB/km, and 0.27 were observed at 850 nm in Ikeja, Calabar, Abuja, and Kano, respectively, during the LV dry season. The variability of visibility and its effects on specific attenuation is moderate in Abuja compared to other stations. The results will find applications in the design and implementation of the FSO communication link for optimum performance in tropical regions. Full article

Asphalt pavements are widely used in airports due to their excellent skid resistance, vibration damping, and ease of construction. However, traditional fog seal materials often suffer from insufficient adhesion between fine sand and the emulsified asphalt binder, resulting in limited durability of the maintenance effect. This study aims to optimize the design of traditional fog seal materials and systematically evaluate their surface and durability performance. Firstly, a composite modified emulsified asphalt was prepared as the sand suspension slurry for the sand-containing fog seal. Through the dry wheel abrasion test, the optimal fine aggregates content was determined for four different spraying amounts (0.8, 0.9, 1.0, and 1.1 kg/m²). When the proportion of fine aggregates increases, the spraying amount needs to be increased accordingly to ensure the wrapping effect. Subsequently, pavement performance evaluation was conducted based on several indicators, including surface curing time, British Pendulum Number (BPN) friction coefficient, permeability coefficient, and mass loss rate. The results showed that the designed sand-containing fog seal significantly reduced surface curing time and exhibited superior skid resistance and permeability property compared to styrene-butadiene rubber (SBR)-modified emulsified asphalt. After freeze–thaw cycles, the maximum decrease in friction coefficient was 10.2%, and the mass loss rate after abrasion was approximately 67%, which were lower than those of SBR-modified emulsified asphalt (22.2% and 81%, respectively). Finally, considering the comprehensive performance comparison and evaluation, the optimal mix proportion was determined as 1.0 kg/m² spraying amount with 30% fine aggregates content. The findings of this study provide practical support for improving the durability and service life of airport asphalt pavements. Full article

A total of 1.6 million tons of personal protective equipment (PPE) waste has been generated daily since 2019 and this production has not abated since that time. Within PPEs, isolation gowns make up the largest percentage by weight of landfill waste. This study aimed to evaluate the effectiveness of rapid, reproducible disinfection protocols to help facilitate safe reuse and minimize risks from microbial contamination. Disinfection of isolation gowns via fogging with hydrogen peroxide (HP) and hypochlorous acid (HC) were evaluated in the present study compared to standard ethylene oxide (EO) sterilization. This study was conducted at VCA West Coast Specialty and Emergency Animal Hospital in the United States. Ten isolation gowns (control) were cultured on tryptic soy agar contact plates in 10 predetermined areas to determine microbial load and morphology/types on non-sterile gowns before use. Following this, 10 gowns were fogged with 12% HP, and then once drying was complete, they were cultured in the predetermined areas for microbial load and morphology/types. This procedure was repeated with another set of 10 gowns fogged with 500 ppm HC. Lastly, 10 gowns were sterilized with EO using standard protocol and cultures were performed similarly. Median CFU (colony-forming unit) counts at 48 h for control, EO, HP, and HC were 4.5, 0, 0, and 0; at 72 h, they were 107, 0, 0, and 0, respectively. No significant difference was noted between the disinfection groups; post hoc pairwise analysis showed that the CFU counts for the disinfection groups were significantly lower than those for the control. The median percent reduction at 48 h for EO, HP, and HC was 100, 100, and 100; at 72 h, it was 100, 100, and 100, respectively. No significant difference was detected among the groups. The median number of microbe types for control, EO, HP, and HC was 2.5, 0, 0, and 0; there was no difference between the disinfection groups, but the number of microbe types was significantly higher for the control than for the disinfection groups. EO is environmentally toxic, expensive, and carcinogenic; it requires prolonged disinfection cycle times, expensive equipment, and trained personnel. This study suggests that HP and HC provide a cost-effective, relatively nontoxic, environmentally safe, and comparatively short disinfection time option for the disinfection and reuse of isolation gowns that does not require trained personnel or specialized equipment. Full article

Potassium dihydrogen phosphate (KDP) crystals, vital for high-power laser systems, pose significant machining challenges due to their brittleness, low hardness, and hygroscopic properties. Achieving crack-free, high-precision surfaces is essential but complex. Single-point diamond fly-cutting (SPDF) is the primary method, yet it exposes tools to high mechanical stress and heat, accelerating wear. In dry cutting, worn tools develop adhesive layers that detach, causing scratches and degrading surface quality. Traditional wet cutting improves surface finish but leaves residual fluids that contaminate the surface with metal ions, leading to optical degradation and fogging. To address these issues, this study explores mixed-fat-based minimum quantity lubrication (MQL) as a sustainable alternative, comparing two lubricants: biodegradable-base mixed ester lubrication (BBMEL) and hydrocarbon-based synthetic lubricant (HCBSL). A comprehensive evaluation method was developed to analyze surface roughness, tool wear, and subsurface damage under dry cutting, MQL-BBMEL, and MQL-HCBSL conditions. Experimental results show that MQL-BBMEL significantly enhances machining performance, reducing average surface roughness by 27.77% (Sa) and 44.77% (Sq) and decreasing tool wear by 25.16% compared to dry cutting, outperforming MQL-HCBSL. This improvement is attributed to BBMEL’s lower viscosity and higher proportion of polar functional groups, which form stable lubricating films, minimizing friction and thermal effects. Structural analyses confirm that MQL-BBMEL prevents KDP crystal deliquescence and surface fogging. These findings establish MQL-BBMEL as an eco-friendly, high-performance solution for machining brittle optical materials, offering significant advancements in precision machining for high-power laser systems. Full article

Water scarcity presents one of the greatest challenges of our time. Especially in naturally water-scarce regions, the need for additional water resources is rising, requiring innovative and site-adapted technologies. The decision for a specific technology is mostly associated with high investment costs and a long life cycle time, which requires a conscientious and transparent decision-making process. In this review, such a framework is developed for selected non-conventional water technologies and strategically evaluated with the goal to support a sustainable technology application based on specific boundary conditions. This is achieved by a matrix-based assessment and the development of key indicators respecting the availability, applicability, environmental impact, scalability, and economic viability of the selected technologies. Based on a wide literature review, the developed methodology involves a systematic comparison of technologies for desalination, water reuse, groundwater utilization, agricultural reuse, and unconventional approaches like cloud seeding, dew water, and fog water harvesting. The developed indicators cover most parameters of the respective categories based on the individual designs. Subsequently, the different technologies are analyzed by a matrix-based evaluation, highlighting various strengths and weaknesses and providing insights into technology application based on regional conditions. The discussion interprets the findings, deriving implications for dry environments, acknowledging limitations, and suggesting pathways for future research. The matrix-based evaluation is illustrated by an example from the Jordan Valley for a brackish water desalination plant. Through this analytical framework, this study contributes to the discourse on sustainable water solutions and a transparent decision-making process, as well as offers valuable insights for policymakers, researchers, and industries during a decision-making progress. Full article

This study aims to assess the stability of silica gel/polymer composites designed for open-cycle air dehumidification, humidification, and heat storage by employing a comprehensive set of characterization methods. To evaluate their resistance to various environmental factors, the materials were subjected to a series of aging treatments: (i) repeated adsorption/desorption cycles under representative operational conditions; (ii) post-drying at 30 °C, 40 °C, and 60 °C; (iii) immersion in water for 30 days; (iv) exposure to a salt–fog environment for 30 days; and (v) accelerated aging by alternation between wet and dry cycles. Prolonged exposure to liquid water significantly reduced the material’s stability, resulting in an 83% reduction in tensile strength after 30 days of immersion. However, discontinuous exposure to liquid water at low drying temperatures did not critically affect the material’s mechanical properties during wet/dry cycles. Furthermore, post-drying (performed at 22 °C and 50% RH) allows the recovery of mechanical performance, with a tensile strength reached comparable to those of the unaged composites. Similarly, adsorption/desorption cycles in water vapor did not trigger degradation in the material, with its water vapor adsorption capacity remaining comparable to the unaged material after 100 cycles. The results confirm the reliability of these composite materials as to their potential uses in open-cycle dehumidification, humidification, and heat-storage applications. Full article

Background/Objectives: In healthcare environments with high microbial loads, effective infection control measures are critical for reducing airborne and surface contamination. One of the novel modalities in the achievement of these goals is the use of antimicrobial mists, such as droplets, in the form of dry fog. Although the usage of dry fog in the disinfection of contained healthcare microenvironments is well known, the effect of such a system in terms of a meaningful reduction in the microbial burden in an open inpatient ward is unclear. Our objective was to assess the impact of scheduled dry fogging on microbial reduction in such settings. Methods: We collected air and surface samples from rooms receiving daily, biweekly, or no fogging (controls) over six months, establishing the baseline contamination and evaluating the reduction trends in treated rooms. The “reduction effect” was measured by tracking microbial isolation trends before and after treatment, while the “degree of reduction” assessed differences across rooms with varied disinfection schedules. Results: The results indicate that scheduled dry fogging significantly reduced microbial loads in treated rooms, especially with daily disinfection (SE = 64.484, p = 0.002). The airborne contamination in treated rooms showed a strong downward trend over time (SE = 19.192, p < 0.001). Surface contamination remained challenging due to frequent recontamination; however, treated rooms exhibited a consistent reduction in microbial presence (SE = 2.002, p = 0.010), confirming dry fogging’s role as a valuable adjunct to routine cleaning. Conclusions: In conclusion, this study highlights that dry fogging effectively reduces microbial loads in open, high-traffic healthcare environments, supporting its use as part of a multimodal infection control strategy. Full article

Collecting fog water is crucial for dry areas since natural moisture and fog are significant sources of freshwater. Sustainable and energy-efficient water collection systems can take a page out of the cactus’s playbook by mimicking its native fog gathering process. Inspired by the unique geometric structure of the cactus spine, we fabricated a bioinspired artificial fog collector consisting of cactus spines featuring barbs of different sizes and angles on the surfaces for water collection and a series of microcavities within microchannels inspired by Nepenthes Alata on the bottom to facilitate water flowing to the reservoir. However, replicating the actual shape of the cactus spine using conventional manufacturing techniques is challenging, and research in this area has faced a limitation in enhancing water-collecting efficiency. Here, we turned to 3D printing technology (vat photopolymerization) to create bio-mimetic fog collectors with a variety of geometric shapes that would allow for the most effective conveyance and gathering of water. Various barb sizes, angles between each barb in a single array, spine and barb arrangements, and quantity of barbs were tested experimentally and numeric analysis was carried out to measure the volume of water collected and optimize the mass rate. The result shows that optimal fog collection is with a mass flow rate of 0.7433 g/min, with L_i = 900 μm, θ = 45°, ϕ = 90°, N_b = 2, and N_s = 5. This study presents a sustainable and ecologically sound method for efficiently collecting humid air, which is expected to be advantageous for the advancement of future-oriented fog-collection, water-transportation, and separation technologies. Full article

The quality of indoor air is dependent on a number of factors, including the presence of microorganisms that colonize the building materials. The potential for health risks associated with microbial contamination is a significant concern during the renovation of buildings. The aim of this study was to assess the impact of two reconstruction methods for historic buildings on air quality. The two reconstruction procedures were facadism, which preserves only the façade, demolishing the rest of the building and constructing a new building, and complete reconstruction, which involves internal renovation with a less intensive demolition. A total of 70 + 70 air samples, as well as surface and dust samples, were collected throughout the course of the reconstruction of the two buildings. In the case of facadism, total colony counts were found to be 2–4 times higher indoors than outdoors, even at the initial stage of the works. High concentrations of Aspergillus and Penicillium spp. were detected. During the less intensive reconstruction, the total colony count in the indoor air samples was initially lower at almost every sampling point than at the outdoor levels. With regard to fungi, Penicillium species were initially present at lower conidia concentrations, followed by Aspergillus species over time. In both buildings, elevated concentrations of airborne fungi were detected during the main reconstruction period. The fungal genera found in the indoor air were also detected on surfaces and in dust samples. Outdoor air samples collected from the vicinity of the buildings revealed elevated fungal counts at multiple sampling points, particularly in the case of facadism. Disinfection with dry fogging was implemented twice throughout the entire interior of the buildings. Following the first disinfection process, there was no notable decrease in colony-forming unit (CFU) counts in either building. However, the second disinfection resulted in a reduction in microbial concentration in the air. Our study confirms that the renovation of historical buildings can result in an elevated prevalence of fungal bioaerosols, which can be harmful to occupants. While the impact of the reconstruction remained within the range of urban background variability at distant (>1 km) locations, it caused local microbial contamination, often exceeding the detection limit in near-site samples. Full article