Search Results (35)

This study evaluated whether commonly used household cleaning agents affect the surface microhardness of acrylic and copolyester materials used in pediatric removable appliances and sought to identify safe options for daily home cleaning. Standardized acrylic and copolyester specimens were exposed to a short-term, clinically relevant brushing regimen using tap water (control), children’s toothpaste, liquid soap, antibacterial liquid soap, 20% saline solution, or 20% sodium bicarbonate (“carbonated”) solution. Surface microhardness was assessed with Vickers testing, and surface features were examined by light microscopy. In the acrylic group, antibacterial liquid soap and the carbonated solution were associated with reduced microhardness (Spearman ρ = −0.622 and −0.532, respectively; both p < 0.001) and more pronounced surface alterations. In the copolyester group, antibacterial liquid soap showed a significant inverse association with microhardness in regression analysis (p = 0.032), while the other agents showed no statistically significant relationships (p > 0.05). Clinically, antibacterial liquid soap should be avoided for routine cleaning of both acrylic and copolyester appliances, and sodium bicarbonate–based carbonated solutions may be detrimental to acrylic. Children’s toothpaste and ordinary liquid soap appear to be practical, safer alternatives for daily use. Full article

Controlling banana aphid (Pentalonia nigronervosa) vectors of banana bunchy-top disease is crucial for integrated disease management. Synthetic insecticides, though effective in aphid control, pose health and environmental risks. Biorational pesticides (including botanicals and soaps) are safer alternatives. This study screened four fresh and fermented aqueous plant extracts (chili pepper, garlic, neem, and peppermint) and three soaps (bathing, laundry bar, and liquid soap) singly or in mixtures against banana aphids through in vitro and in vivo experiments. Aphid-inoculated banana leaf-blade disks were used for the in vitro studies over 96 h. Potted plantlets were used for the in vivo studies over eight weeks. Applying these preparations resulted in significant (p ≤ 0.05) aphid mortality (28.6 to 100%) compared to the water control (3.3%) at 96 h post-spray (hps). In vitro, a single application of nimbecidine^® (Azadirachtin 0.03%), garlic, chili-pepper botanicals, insecticidal, and bathing soap caused >50% mortality at 96 hps. Mixed applications of chili pepper, garlic-based, and neem botanicals with soap caused >70% mortality at 96 hps in vitro. Binary mixtures of neem oil, garlic, fermented garlic, or fermented peppermint with insecticidal soap, and neem oil with bar soap, were promising in vivo, reducing the aphid populations to <20/plant compared to the control, which had >200 aphids after week 8. However, these potential preparations incurred a higher cost (USD 1.30/banana mat) compared to the synthetic pesticide (USD 0.022/mat). Thus, biorational mixtures have a potential to effectively control banana aphids. Full article

Biomass briquettes are increasingly used as renewable solid fuels, yet their durability under humid storage remains a key limitation. This study evaluated the mechanical performance and water resistance of briquettes made from fine (0–1 mm) and coarse (0–3 mm) charcoal fractions using molasses as a primary binder, polyvinyl alcohol (PVA, 3–7%) as a synthetic binder, and liquid soap (1–9%) as a surfactant additive. Compressive strength was measured in the dry state, after four days of water immersion, and after re-drying, while water absorption was monitored over immersion times from 15 min to 4 days. Fine-fraction briquettes showed higher strength and lower water uptake than coarse fractions, with optimal PVA contents of 6–7% providing maximum dry and post-drying strength. Moderate soap addition (2–3%) improved binder dispersion and early wet strength, whereas higher levels (>5%) reduced durability. Water absorption kinetics indicated that particle size controlled early swelling, while binder composition influenced the rate but not the final saturation. The best performance in humid storage was achieved by 0–1 mm + 4% PVA and 0–1 mm + 5% PVA + 3% soap formulations. These results support the formulation of eco-friendly binder systems that balance strength, moisture resistance, and cost for large-scale biomass briquette production. Full article

This article presents a collection of schlieren visualizations captured using a custom-built, laboratory-based imaging system, designed to explore a wide range of flow and refractive phenomena. The experiments were conducted as a series of observational case studies, serving as educational bloc notes for students and researchers working in fluid mechanics, optics, and high-speed imaging. High-resolution images illustrate various phenomena including shockwave propagation from bursting balloons, vapor plume formation from volatile liquids, optical surface imperfections in transparent materials, and the dynamic collapse of soap bubbles. Each image is accompanied by brief experimental context and interpretation, highlighting the physical principles revealed through the schlieren technique. The resulting collection emphasizes the accessibility of flow visualization in a teaching laboratory, and its value in making invisible physical processes intuitively understandable. Full article

Studies assessing the long-term effects of brushing with cleaning and disinfecting agents on surface roughness and biofilm accumulation on the three-dimensionally (3D) printed resins remain scarce. This study aimed to evaluate the effects of different solutions and simulated brushing times on the surface roughness and biofilm formation on heat-cured and 3D-printed denture base resins. Discs samples (10 mm × 1.2 mm) were prepared and randomly assigned to brushing treatments using the following solutions: distilled water, disinfectant liquid soap and dentifrice. The specimens (n = 9) were subjected to 10,000, 20,000 and 50,000 cycles to simulate 1, 2 and 5 years of brushing, respectively. The control group consisted of unbrushed samples. Surface roughness (Ra) was measured. Candida albicans biofilm formation was evaluated by counting colony forming units, cellular metabolic activity, and qualitative and quantitative analysis through confocal fluorescence microscopy. A significant increase in roughness was observed in both resins after two years of simulated brushing, mainly with dentifrice. After two years of brushing, an increase in the number of cells and metabolism of C. albicans was observed, in agreement with the fluorescence and biofilm thickness results. Brushing with dentifrice increased the roughness of heat-cured and 3D-printed resins and potentially increased C. albicans biofilm formation. Full article

In this study, canola oil was used as a natural enriched source of C18 fatty acids and coconut oil as a natural enriched source of C12 fatty acids. The study synthesized five potassium carboxylate (RCOO⁻K⁺) liquid soaps via saponification of coconut–canola oil blends (100:0, 75:25, 50:50, 25:75, 0:100) using a novel in situ dissolution method with controlled KOH addition to prevent solid paste formation. The water demand required to dissolve RCOO⁻K⁺ and mitigate soap crystallization was determined, increasing from 1.76 to 5.18 g H₂O/g oil as canola oil content rose, with soap concentration decreasing from 55.1% (100:0) to 18.5% (0:100). Reaction kinetics revealed faster KOH depletion in coconut oil-rich blends (100:0, 75:25, 50:50; 2 h) compared to canola oil-rich blends (25:75, 0:100; 8 h). Key soap properties, including foam stability, detergency, wettability, viscosity, and thermal behavior, were assessed. The 50:50 blend exhibited the highest foam stability due to the synergistic effects of medium-chain saturated (e.g., laurates) and long-chain unsaturated (e.g., oleates) RCOO⁻K⁺. The short, saturated chains promoted rapid foam formation, while the longer, unsaturated chains enhanced foam film stability. RCOO⁻K⁺ detergency on hair tresses with artificial sebum ranged from 16.9% to 29.7% and was relatively higher compared to sodium lauryl sulfate, sodium laureth sulfate, cocamidopropyl betaine, and sodium cocoyl glutamate (6.1–13.2%) but lower compared to sodium isethionates (34.2%). RCOO⁻K⁺ wettability on cotton textiles improved with higher coconut oil content. RCOO⁻K⁺ contact angles on artificial sebum surface (6.1–13.7°) demonstrated excellent wettability, effectively penetrating and emulsifying hydrophobic residues. Viscosity ranged from 13–45 mPa·s with Newtonian Flow-type behavior. No crystals were observed in the soaps when cooled in the range of 60 to −30 °C. These results demonstrate RCOO⁻K⁺ soaps as tunable, sustainable liquid soaps with performance optimized by adjusting the oil blend ratios. Full article

This research assesses the impacts of five cleaner production (CP) profiles of soap products and the overall equipment effectiveness (OEE) of liquid detergent production lines. A simulation model was built to depict the “As-Is” condition, and then the overall equipment effectiveness was calculated. Results showed high rejection rates and bottlenecks, resulting in long average cycle times and waiting times, as well as low production rates and machine utilization. Consequently, lean, agile, and resilient actions were utilized to enhance the OEE of the line’s processes. The improvement results showed that the bottle placement, filling, labeling, and taping processes were enhanced by 237%, 4.67%, 5.41%, and 26.02%, respectively. Moreover, the smallest percentages of availability, quality, and performance were 97.46%, 99.82%, and 81.56%, respectively, indicating a considerable enhancement in the performance of the line’s processes. Further, cleaner production assessment was performed on soap products to estimate environmental profile indices for raw material, energy, product, waste, and packaging. The estimated overall environmental index was 107.93, with liquid waste contributing the largest index value. Therefore, a proposal for a water treatment system was suggested and then assessed. In conclusion, lean, agile, and resilient actions were found to be effective in enhancing the OEE of production processes. Moreover, cleaner production provided valuable support to decision-makers in determining the appropriate actions for improving the OEE and environmental performance of the technological processes and products of detergent production lines. Full article

In the silk production process, cocoons from Bombyx mori worm are degummed and separated from their components. This step generates large residual quantities of an aqueous solution containing various chemical substances, including sericin—a protein that, when discarded improperly, negatively impacts the environment. Sodium bicarbonate and coconut soap are commonly used in the degumming process. The phosphates in the soap and the sodium bicarbonate increase the biological oxygen demand (BOD) and chemical oxygen demand (COD), leading to water contamination. In this study, a Box–Behnken experimental design was used to maximize the extraction of sericin through a conventional extraction under chemical-free conditions. From a total of 45 experiments, the optimal extraction conditions were identified as a solid-to-liquid ratio of 1:20 w/v, a temperature of 120 °C, and 90 min of extraction time. Sericin yields ranged from 9% to 18%. Infrared spectroscopic characterization of the extracted sericin confirmed the presence of protein-specific functional groups and common interactions associated with β-sheet structures. Fractions of high molecular weight (50 kDa to 200 kDa), identified by means of Sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) analysis, demonstrate the potential functionality of extracted sericin for the development of biopolymer films useful in biomedical and food industry applications. The optimized methodology is a good alternative to recycle the waste of sericulture chain for obtaining extracts enriched in sericin, as well as to promote the mechanization of artisanal production processes. Full article

This research aims to investigate and quantify the possible presence of microplastics (MPs) in usual skin-cleansing products (i.e., liquid soap, micellar water, and micellar cleansing oil), the most popular from the market in terms of brand and customer confidence. Therefore, optical microscopy and micro-Fourier transform infrared spectroscopy (micro-FTIR) were used to determine the MPs’ number, color, shape, size, and chemical composition. For the first time, the results were correlated with the possible exposure paths (i.e., inhalation, ingestion, or adsorption) to assess the human health risk of the analyzed micellar-based cleansers in terms of chronic total exposure dose to microplastics. Finally, a statistical analysis was added to this study for source prediction of MPs in skin-cleansing samples in terms of morphology, chemical composition, and other factors (i.e., brand, packaging, etc.). The various exposures and toxicities of MPs were assessed in terms of potential health risk, knowing that their toxic effect depends on the polymeric structure strongly linked with the size, shape, and concentration in the products. Full article

Slips and fall-related accidents cause a significant number of injuries in hospitals. Due to constant movement of doctors and nurses across different departments in hospitals such as OPD, trauma centres, and ICUs, there are possible interactions of their footwear with slippery floorings (e.g., wet or with soap suds), which may cause unexpected slips. To date, there is a lack of understanding on the traction of different footwear worn by hospital staff. This impedes the selection of appropriate floorings and footwear for preventing slips and falls in hospitals. In this work, the traction performances of twelve common footwear designs, worn by hospital staff, were tested on three different floorings at important locations, i.e., an outpatient department, trauma centre, and ICU entrance, at a busy public hospital. Oblique tread patterns are recommended for moderately rough floors under dry and Lizol conditions. Horizontally oriented patterns are better for smoother floors in dry conditions, while vertically oriented patterns are ideal for areas with frequent contaminant exposure. No specific recommendation can be made for soap-contaminated floors due to the contaminant’s high viscosity. The results also indicated the strong influence of flooring roughness on the measured traction, over footwear tread parameters. Also, liquid soaps were observed to significantly reduce footwear–floor traction. The findings are anticipated to be valuable to hospital management for the selection of appropriate high-traction floorings, and provide important guidelines for footwear selection, for the mitigation of slips and falls in hospitals. Full article

Gelled fuels are rheologically complex, non-Newtonian fluids. They combine the benefits of both liquid and solid states, reducing risks of leakage, spilling, and sloshing during storage while maintaining the ability to be sprayed inside a combustion chamber. Additionally, suspending energetic particles, such as metal powders of aluminum and boron, can significantly enhance their energy density compared to conventional liquid fuels. In this study, several kerosene-based and ethanol-based formulations were experimentally investigated, using both organic and inorganic gelling agents. The compositions were optimized in terms of the gellant amount and manufacturing process. Some of the most promising gellants for kerosene include fatty acids, such as Thixcin^® R or THIXATROL^® ST, and metallic soaps, such as aluminum stearate and zinc stearate. The effects of various co-solvents were assessed, including ketones (methyl isoamyl ketone, methyl ethyl ketone, and acetone) and alcohols (ethanol and octadecanol). Sugar polymers like hydroxypropyl cellulose were tested as gelling agents for ethanol. A preliminary rheological analysis was conducted to characterize their behavior at rest and under shear stress. Finally, a novel approach was introduced to study the stability of the gels under vibration, which was derived from a realistic mission profile of a ramjet. Finally, the ideal gravimetric specific impulse was evaluated through ideal thermochemical computations. The results showed that promising formulations can be found in both kerosene-based and ethanol-based gels. Such compositions are of interest in practical airbreathing applications as they have demonstrated excellent stability under vibration, ideal combustion properties, and pronounced shear-thinning behavior. Full article

In this study, online ambient volatile organic compounds (VOCs) were collected at an urban site of Zhengzhou in Central China during February 2018. The VOCs characteristics, source contributions and the Chinese New Year (CNY) effects have been investigated. During the sampling period, three haze periods have been identified, with the corresponding VOCs concentrations of (92 ± 45) ppbv, (62 ± 18) ppbv and (83 ± 34) ppbv; in contrast, the concentration during non-haze days was found to be (57 ± 27) ppbv. In addition, the festival effects of the CNY were investigated, and the concentration of particulate matter precursor decreased significantly. Meanwhile, firework-displaying events were identified, as the emission intensity had been greatly changed. Both potential source contribution function (PSCF) and the concentration weighted trajectory (CWT) models results indicated that short-distance transportation was the main influencing factor of the local VOCs pollution, especially by transport from the northeast. Source contribution results by the positive matrix factorization (PMF) model showed that vehicle exhaust (24%), liquid petroleum gas and natural gas (LPG/NG, 23%), coal combustion (21%), industrial processes (16%) and solvent usages (16%) were the major sources of ambient VOCs. Although industry and solvents have low contribution to the total VOCs, their secondary organic aerosol (SOA) contribution were found to be relatively high, especially in haze-1 and haze-3 periods. The haze-2 period had the lowest secondary organic aerosol potential (SOAp) during the sampling period; this is mainly caused by the reduction of industrial and solvent emissions due to CNY. Full article

The objective of this study was to develop effervescent cleansing tablets that can be dissolved and turned into liquid soap, which can be used for bathing or soaking the body. The asiatic-acid-loaded solid lipid microparticles (AASLMs) were prepared via the hot emulsification method followed by cold re-solidification and then freeze-dried to obtained dry powder. The physicochemical properties such as morphology and % entrapment efficiency (%EE) were evaluated. The results revealed that AASLMs have an irregular shape, and the %EE for the resulting AASLMs was 92.04 ± 3.43%. The tablets were manufactured via the direct compression technique. The compatibility test was conducted to ensure that the excipients are compatible with the active ingredient. The angle of repose, Carr’s index, and Hausner’s ratio were studied to evaluate the flowability of the powder blend before compression. The weight of each tablet was set to 1000 mg, and physicochemical characteristics, in vitro dissolution, ex vivo cleansing efficacy, and stability were evaluated. The results showed that the active ingredient was compatible with other excipients, as the results obtained from FTIR spectra indicated the absence of potential chemical interaction between the active ingredient and excipients used in this study. Additionally, all formulations had good flow properties. The effervescence times of selected formulations, F2 and F3, were <5 min, with favorable pH and hardness values. The friability values of all formulations exceeded 1% because the excipients used in effervescent tablets are very fragile. The release of asiatic acid (AA) from the tablets was dependent on the concentration of SLS. In an ex vivo test, it was discovered that the developed products F2 and F3 showed much more effective cleansing efficacy than water. Nevertheless, brown spots appeared in the tablets and the AA content was significantly decreased in both tested formulations after 3 months’ storage at 40 ± 2 °C/75% RH ± 5% RH. The stability study revealed that the developed products were not stable at high temperature and humidity. Therefore, it is recommended that the developed effervescent tablets are not stored at a high temperature. Full article

Antiseptics, disinfectants, and hand hygiene products can act as reservoirs of Gram-negative bacteria causing healthcare-associated infections. This problem is rarely documented in low- and middle-income countries, particularly in sub-Saharan Africa. In a cross-sectional survey, we assessed the bacterial contamination of antiseptics, disinfectants, and hand hygiene products in two university hospitals in Burkina Faso and Benin. During ward visits and staff interviews, in-use products were cultured for the presence of Gram-negative bacteria. The growth of Gram-negative bacteria was absent or rare in alcohol-based products, povidone iodine, and Dakin solution. Contamination was highest (73.9% (51/69)) for liquid soap products (versus antiseptic/disinfectants (4.5%, 7/157) (p < 0.0001)), mostly used in high-risk areas and associated with high total bacterial counts (>10,000 colony-forming units/mL). Contaminating flora (105 isolates) included Enterobacterales and the Vibrio non-cholerae/Aeromonas group (17.1%) and non-fermentative Gram-negative rods (82.8%). Multidrug resistance was present among 9/16 Enterobacterales (Klebsiella and Enterobacter spp.) and 3/12 Acinetobacter spp., including carbapenem resistance (Acinetobacter baumannii: NDM, Pseudomonas stutzeri: VIM). The risk factors for contamination included the type of product (cleaning grade and in-house prepared liquid soap), use of recycled disposable containers and soft drink bottles, absence of labeling, topping-up of containers, dilution with tap water (pharmacy and ward), and poor-quality management (procurement, stock management, expiry dates, and period after opening). Full article

We conducted a systematic review of healthcare-associated outbreaks and cross-sectional surveys related to the contamination of antiseptics, disinfectants, and hand hygiene products in healthcare settings in low- and middle-income countries (PROSPERO CRD42021266271). Risk of bias was assessed by selected items of the ORION and MICRO checklists. From 1977 onwards, 13 outbreaks and 25 cross-sectional surveys were found: 20 from Asia and 13 from Africa. Products most associated with outbreaks were water-based chlorhexidine, chlorhexidine-quaternary ammonium compound combinations (7/13), and liquid soap products (4/13). Enterobacterales (including multidrug-resistant Enterobacter cloacae, Klebsiella pneumoniae, and Serratia marcescens) and non-fermentative Gram-negative rods were found in 5 and 7 outbreaks and in 34.1% and 42.6% of 164 isolates, respectively, from cross-sectional surveys. Risk factors included preparation (place, utensils, or tap water high and incorrect dilutions), containers (reused, recycled, or inadequate reprocessing), and practices (topping-up or too long use). Potential biases were microbiological methods (neutralizers) and incomplete description of products’ identity, selection, and denominators. External validity was compromised by low representativeness for remote rural settings and low-income countries in sub-Saharan Africa. Outstanding issues were water quality, biofilm control, field-adapted containers and reprocessing, in-country production, healthcare providers’ practices, and the role of bar soap. A list of “best practices” to mitigate product contamination was compiled. Full article