Short Contact Time Research Articles

Nonlinear low-velocity impact of magneto-electro-elastic plates with initial geometric imperfection

Magneto-electro-elastic (MEE) materials are widely used in the aviation and spaceflight area, attributed to magneto-electric coupling effect of MEE materials which can achieve mutual energy conversion in complex physical fields. This article takes the imperfect MEE plate as the research object to explore the nonlinear low-velocity behaviors, and the influence of multiple physical fields such as electric, magnetic and temperature fields are taken into account. Based on Maxwell's equations and first-order shear deformation theory (FSDT), the constitutive equation of MEE plate is obtained, and the nonlinear motion equations are derived using the Euler-Lagrange principle. Subsequently, with the aid of the Galerkin method, the ordinary differential equations are obtained by discretizing the partial differential equations. Then the low-velocity impact problem is solved using the Runge-Kutta method. Finally, the impacts of unknown factors upon the dynamic behaviors of the MEE plate are illustrated particularly. It can be found that the magnetic and electric potentials have opposite effects on the impact displacement of the plate, and the MEE plate with the lowest volume fraction of BaTiO3 has the smallest center displacement and the shortest contact time, but has the maximum contact force.

Preparation of Highly Effective Antibacterial Cotton Fabrics Based on Bifunctional Reactive N-Halamine

Two novel halogenated triazine amine N-halamine antimicrobial precursors, sulfuric acid mono-(2-{4-[4-chloro-6-(2,2,6,6-tetramethyl-piperidin-4-yloxy)-[1,3,5]triazin-2-ylamino]-benzenesulfonyl}-ethyl) ester sodium (PT) and sulfuric acid mono-(2-{4-[4-(3-pyridinecarboxylic sodium)-6-(2,2,6,6-tetramethyl-piperidin-4-yloxy)-[1,3,5]triazin-2-ylamino]-benzenesulfonyl}-ethyl) ester sodium (CPT), were designed, synthesized, and applied onto cotton fabrics to obtain antibacterial properties. The molecular structures of PT and CPT contained two reactive groups of vinyl sulfone and nicotinic acid, which increased the reaction with cotton fabrics compared with other antibacterial agents. The dyeing process of reactive dye was selected as the finishing method due to the similar structures of antibacterial agents to bifunctional group reactive dyes. The treated cotton fabrics were chlorinated with sodium hypochlorite to obtain antibacterial functionality. The chlorinated fabrics achieved outstanding antibacterial properties against Escherichia coli O157:H7 and Staphylococcus aureus with short contact time. Moreover, the stability measurement exhibited that the chlorine on the samples could be repaired by the diluted sodium hypochlorite solution after washing and long-time storage. In addition, the mild low-temperature process reduced fabric damage, and only about 10% and 15% of the original tensile strength was missing after finishing and chlorination in both the warp and weft directions. Compared to the traditional pad–dry–cure technique, the process developed of antimicrobial cotton had some advantages such as low salt, energy savings, and maintaining tensile strength.

Excellent adsorption properties of Mg/Al/Fe LDOs for Cr(VI) in water

Cr(VI), a common wastewater pollutant discharged from metallurgical, electroplating and other industries poses a threat to human health and the ecological environment. Layered double hydroxides (LDHs), which have a strong anion exchange capacity and memory effect, are excellent adsorbents that are widely used for heavy metal adsorption. In this study, we found that Mg-Al-Fe ternary metal oxides (MAF-LDOs) obtained by the calcination of Mg-Al-Fe hydrotalcite-like compounds (MAF-LDHs) had great potential for the treatment of Cr(VI)-containing wastewater. The influences of the adsorption time, Cr(VI) concentrations, pH value and coexisting metal ions were also considered. By using batch adsorption experiments and various characterization tools, it was found that the mechanism of Cr(VI) adsorbed by MAF-LDO involved the use of a memory effect that involved HCrO4- in the reconstruction of laminates. In addition, some laminate -OH groups were protonated to electrostatically attract HCrO4-. The -OH groups in the laminate acted as electron donors to reduce Cr(VI) to Cr(III) that then underwent complexation for the effective removal of Cr(VI). The maximum theoretical adsorption capacity of MAF/LDOs for Cr(VI) was 122.85 mg/g at 20 °C. Furthermore, the MAF-LDO demonstrated excellent stability and reusability. In conclusion, the MAF-LDO exhibited a simple synthesis process, superior adsorption capacity with a short contact time, and a wide pH range of application. Hence, it is well-suited for industrial wastewater treatment and provides new insights for treating Cr(VI)-containing wastewater.

Hydrothermal integration of MoO2–MoS2@rGO nanoframe networks: A promising approach for efficient bacterial disinfection in wastewater

The efficient disinfection of bacterial contaminants in wastewater is a critical challenge in the field of environmental remediation. Herein, we present a novel approach for efficient bacterial disinfection using hydrothermally integrated MoO2–MoS2@rGO nanoframe networks. The developed nanoframe networks exhibit a unique architecture comprising of molybdenum dioxide (MoO2) and molybdenum disulfide (MoS2) impregnated on algae biomass reduced graphene oxide (rGO). The as-synthesized nanoframe networks demonstrate exceptional antibacterial activity against Escherichia coli bacteria. The disinfection efficiency was evaluated by measuring the bacterial viability and observing the morphological changes using scanning electron microscopy. The MoO2–MoS2@rGO nanoframe networks exhibited a remarkable antibacterial effect, achieving a high disinfection rate of 95.8% within a short contact time of 10 min. The efficient bacterial disinfection capability of the nanoframe networks can be attributed to the synergistic effects of MoO2, MoS2, and rGO components. The MoO2 nanoparticles generate reactive oxygen species (ROS), persuading oxidative stress and leading to bacterial inactivation. The MoS2 nanoparticles possess inherent antibacterial properties through the release of Mo and S ions. The rGO nanosheets provide a conductive and stable platform, facilitating the charge transfer during the antibacterial process. Furthermore, the hydrothermal integration method enables easy scalability and cost-effectiveness of the MoO2–MoS2@rGO nanoframe networks. The nanoframe networks can be easily recovered and reused, reducing waste generation and promoting sustainability. Overall, this study presents a promising approach for efficient bacterial disinfection in wastewater using hydrothermally integrated MoO2–MoS2@rGO nanoframe networks. The remarkable antibacterial performance, along with the advantages of scalability and reusability, makes these nanoframe networks a potential candidate for practical applications in environmental remediation and water treatment processes.

Larger Achilles and plantar fascia induce lower duty factor during barefoot running

ObjectivesTendons play a crucial role allowing the storage and release of mechanical energy during the running cycle. Running kinematics, including duty factor, constitute a basic element of the runner's biomechanics, and can determine their performance. This study aimed to analyze the link between Achilles tendon and plantar fascia morphology and running parameters, considering the influence of wearing shoes versus running barefoot. DesignCross-sectional study. Methods44 participants (30 men and 14 women) engaged in two running sessions, one with shoes and one without, both lasting 3 min at a consistent speed of 12 km/h. We captured running kinematic data using a photoelectric cell system throughout the sessions. Before the trials, we measured the thickness and cross-sectional area of both the Achilles tendon and plantar fascia using ultrasound. ResultsThe Pearson test revealed a significant correlation (p < 0,05) between Achilles tendon and plantar fascia morphology and contact time (r > −0.325), flight time (r > −0.325) and duty factor (ratio of ground contact to stride time) (r > −0.328) during barefoot running. During the shod condition, no significant correlation was found between connective tissue morphology and kinematic variables. ConclusionsIn barefoot running, greater size of the Achilles tendon and plantar fascia results in a reduced duty factor, attributed to longer flight times and shorter contact times.

Spent tea waste extract as a green modifying agent of chitosan for aspirin adsorption: Fixed-bed column, modeling and toxicity studies

Aspirin is a prevalent over-the-counter medicine that has been categorized as an emerging contaminant due to its danger to both living things and the environment. This work presents chitosan modified with spent tea waste extract (STWE) via the wet impregnation method as an adsorbent for the enhanced removal of aspirin in a fixed-bed column. The adsorbent (named chitosan-STWE) was successfully synthesized and exhibited a low crystallinity structure, good stability against thermal and acidic conditions, as depicted by HNMR, XRD, TGA, and the dissolution rate of the adsorbent. The adsorption column study reveals that increasing bed height (up to 6 cm) increases the percentage of aspirin removal (up to 40.8 %). Increasing aspirin concentration enhances the amount of aspirin that comes into contact with the chitosan-STWE adsorbent, thereby increasing the adsorption capacity. On the other hand, higher flow rates result in shorter contact times between the adsorbent and adsorbates, which lowers the quantity of aspirin adsorbed. The experimental data are in accordance with the values generated by the Thomas and Yoon-Nelson models, with the maximum adsorption capacity of 61.7 mg/g. The chitosan-STWE adsorbent was determined to be non-toxic, thus safe to be used in wastewater treatment applications.

Polyhexamethylene guanidine hydrochloride as promising active ingredient for oral antiseptic products to eliminate microorganisms threatening the health of endangered wild cats: a comparative study with chlorhexidine digluconate.

The aim of this study was to evaluate the antimicrobial efficacy of polyhexamethylene hydrochloride guanidine (PHMGH) compared to chlorhexidine digluconate (CLX) for use as an oral antiseptic during dental procedures in wild cats. This research is crucial due to limited information on the diversity of oral microorganisms in wild cats and the detrimental local and systemic effects of oral diseases, which highlights the importance of improving prevention and treatment strategies. Samples were collected from the oral cavities of four Puma concolor, one Panthera onca, and one Panthera leo, and the number of colony-forming units per milliliter (CFU/mL) was counted and semi-automatically identified. The antimicrobial susceptibility profile of bacterial isolates was determined using minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and time-kill kinetics of PHMGH and CLX. A total of 16 bacterial isolates were identified, consisting of six Gram-positive and 10 Gram-negative. PHMGH displayed MIC and MBC from 0.24 to 125.00 μg/mL, lower than those of CLX against three isolates. Time-kill kinetics showed that PHMGH reduced the microbial load by over 90% for all microorganisms within 30 min, whereas CLX did not. Only two Gram-positive isolates exposed to the polymer showed incomplete elimination after 60 min of contact. The results could aid in the development of effective prevention and treatment strategies for oral diseases in large felids. PHMGH showed promising potential at low concentrations and short contact times compared to the commercial product CLX, making it a possible active ingredient in oral antiseptic products for veterinary use in the future.

Stable and impalement-resistant superamphiphobic coatings enabled by phase-separated adhesive for anti-adhesion of viscous liquids with low surface tension

Superamphiphobic coatings have great potential in various fields but surfer from weak mechanical stability, low impalement resistance and poor repellency to viscous liquids with low surface tension. Here, we report stable and impalement-resistant superamphiphobic coatings enabled by phase-separated adhesive for anti-adhesion of viscous liquids with low surface tension. By fluorination of silica (F-silica) nanoparticles and solvent induced phase separation of an adhesive, a homogeneous suspension was obtained, which could be readily used for preparing superamphiphobic coatings via spray-coating. The effects of phase separation degree and adhesive/F-silica mass ratio on superamphiphobicity, impalement resistance and mechanical stability of the coatings were studied. The coatings have a hierachical micro-/nanostructure and numerous perfluorodecyl groups on the surface. Thus, the coatings show excellent static and dynamic superamphiphobicity, e.g., high contact angles, low sliding angles, high maximum release height, short solid-liquid contact time and large bouncing height for various liquids with high viscosity and low surface tension. The coatings also show excellent mechanical stability, good chemical and temperature stability. Furthermore, the coatings are applicable onto diverse substrates and could be easily scaled-up.

Merits and Limitations of Radical vs. Nonradical Pathways in Persulfate-Based Advanced Oxidation Processes.

Urbanization and industrialization have exerted significant adverse effects on water quality, resulting in a growing need for reliable and eco-friendly treatment technologies. Persulfate (PS)-based advanced oxidation processes (AOPs) are emerging as viable technologies to treat challenging industrial wastewaters or remediate groundwater impacted by hazardous wastes. While the generated reactive species can degrade a variety of priority organic contaminants through radical and nonradical pathways, there is a lack of systematic and in-depth comparison of these pathways for practical implementation in different treatment scenarios. Our comparative analysis of reaction rate constants for radical vs. nonradical species indicates that radical-based AOPs may achieve high removal efficiency of organic contaminants with relatively short contact time. Nonradical AOPs feature advantages with minimal water matrix interference for complex wastewater treatments. Nonradical species (e.g., singlet oxygen, high-valent metals, and surface activated PS) preferentially react with contaminants bearing electron-donating groups, allowing enhancement of degradation efficiency of known target contaminants. For byproduct formation, analytical limitations and computational chemistry applications are also considered. Finally, we propose a holistically estimated electrical energy per order of reaction (EE/O) parameter and show significantly higher energy requirements for the nonradical pathways. Overall, these critical comparisons help prioritize basic research on PS-based AOPs and inform the merits and limitations of system-specific applications.

Open-framework hybrid zinc/tin selenide as an ultrafast adsorbent for Cs+, Ba2+, Co2+, and Ni2+

Efficient adsorption of radioactive 137Cs+ and 60Co2+ and their decay products 137Ba2+ and 60Ni2+ bears significance for hazard elimination in case of nuclear emergency, which relies on the adsorption rate enhancement that takes advantages of compositional and structural optimization. Herein, we report a zinc-doped selenidostannate constructed from T2-supertetrahedral clusters, namely K3.4(CH3NH3)0.45(NH4)0.15Zn2Sn3Se10·3.4 H2O (ZnSnSe‐1K). The soft Se and micro-porosity synergistically endow this material with a binding affinity to Cs+, Ba2+, Co2+, and Ni2+ ions and ultrafast kinetics with R > 97.6% in 2–60 min. In particular, ZnSnSe‐1K can remove 99.34% of Cs+ in 2 min (KdCs > 1.5 × 105 mL g−1), contributing to a record rate constant k2 of 9.240 g mg−1 min−1 that surpasses all metal chalcogenide adsorbents. ZnSnSe‐1K exhibits good acid/base tolerance (pH = 0–12), and the adsorption capacities at neutral are 253.61 ± 9.15, 108.94 ± 25.32, 45.76 ± 14.19 and 38.49 ± 2.99 mg g−1 for Cs+, Ba2+, Co2+, and Ni2+, respectively. The adsorption performances resist well co-existing cations and anions, and the removal rates can keep above or close to 90% even in sea water. ZnSnSe‐1K is employed in continuous column and membrane filtration, both of which shows excellent elimination efficiency (R > 99%) for mixed Cs+, Ba2+, Co2+, and Ni2+. Especially, the membrane with an ultrathin (70 µm) ZnSnSe‐1K layer can remove 97–100% Cs+ in suction filtration with a short contact time of 0.33 s. Combined with the simple synthesis, facile elution and great irradiation resistance, ZnSnSe‐1K emerges as a selenide adsorbent candidate for use in environmental remediation especially that involving nuclear waste disposal.

Reverse osmosis pretreatment by a fluidized magnetic ion exchange resin for application in a power plant: Pilot-scale and high-rate operations and foulant characterization

Biofouling is one of the most serious problems in reverse osmosis (RO) operations. Here, we operated a pilot-scale MIEX® system with a high-rate configuration as a pretreatment for an RO system in a water purification plant. The goal was to investigate the RO foulants obtained with and without pretreatment by MIEX®. The MIEX® resin (10 to 300 mL/L) removed dissolved organic matter (DOM) within 5 min. A pilot-scale fluidized reactor with 100 mL/L of MIEX® removed 35.6%, 49.4%, and 56.2% of dissolved organic carbon (DOC) for effective resin doses of 0.03, 0.06, and 0.12 mL/L, respectively. Unknown screening analysis by Orbitrap mass spectrometry revealed that the MIEX® pretreatment decreased or removed 165–363 DOM features with carbon, hydrogen, and oxygen (CHO features) and 145–220 CHO features with N heteroatoms (CHON features) with effective resin doses of 0.03–0.12 mL/L. Moreover, fluorescence EEM revealed the preferential removal of terrestrial DOM, resulting in over half of the protein-like substances remaining in the RO feed. MIEX® selectively removed highly oxygenated DOM features within a short contact time, while condensed aromatic structures and lignin-like compounds were removed after 30 min. Increasing the MIEX® dose resulted in the additional removal of DOM features with less oxygenated characters and longer alkyl chains. The RO system with and without MIEX® pretreatment was similarly fouled by protein-like substances and CHON features; however, the MIEX® pretreatment decreased CHO features and terrestrial DOM foulants. The MIEX® pretreatment decreased organic and irreversible fouling and doubled the RO system lifetime, resulting in lower chemical cleaning and pressure requirements for an identical permeate volume.

Vertical jump performance and the relationship with sprint speed at 20 m and 50 m in professional soccer players.

Background: Jumping and sprinting are essential skills for several sports, especially for soccer, since they allow to determine neuromuscular function and maximum power of the lower extremities in athletes. This study aimed to establish the relationship between vertical jump performance and sprint speed at 20 m and 50 m in professional soccer players. Methods: This study took place from June 2020 to November 2021 with participants from the U20 category of the Colombian professional team Fortaleza CEIF, and the U18 category of the Brazilian professional team Boston City. The vertical jump was assessed with the countermovement jump (CMJ), squat jump (SJ), and rebound jump (RJ) variants using the WheelerJump jump sensor while the sprint was measured using the Winlaborat horizontal encoder. Results: 200 participants from the selected teams were included in this study. Almost perfect correlations (p &lt; 0,05 – r: 0.97) and excellent coefficients of determination (R2: 0.95 – 0.93) were observed between the reactive force index with the mean height of the different jump protocols and the 50-meter sprint speed, indicating that the higher the altitude and/or the higher the reactive force index, the higher the 50-meter sprint speed. The same behavior was found with the 20-meter race, but the correlation levels (p &lt;0,05, r: 0.63-0.62) and the determination coefficients were lower (0.40). Conclusions: The results of this study suggest that, in professional soccer players, long sprint performance like 50 m is strongly correlated and could be accuracy explained by the average height reached in SJ, CMJ, and RJ and by the ability to perform repeated jumps using short contact times, thus increasing the ground reaction forces, which translates into a similar behavior during successive contacts of the player's feet against the ground during the race.

Ni4 complex anchored porous silica for enhanced adsorption of organic pollutants in the wastewater.

In the current study, tetranuclear Ni complex [Ni4(LH)4]·CH3CN (1) (LH3=(E)-2-(hydroxymethyl)-6-(((2-hydroxyphenyl)imino)methyl)phenol) was prepared and incorporated in sulfonic acid functionalized MCM-48 material. This composite nanoporous material was investigated for the adsorption of toxic cationic water pollutant dyes like crystal violet (CV) and methylene blue (MB) from the water solution. Thorough characterization was carried out using a variety of techniques, including NMR, ICP, powder XRD, TGA, SEM, BET, and FT-IR, to verify the phase purity, existence of guest moiety, material morphology, and other crucial variables. The adsorption property was increased with the metal complex immobilization on the porous support. The effect of various parameters on the adsorption process was discussed, including adsorbent dosage, temperature, pH, NaCl concentration, and contact time. Maximum dye adsorption was found at 0.2 mg/ml adsorbent dosage, 10 ppm dye concentration, 6-7 pH, 25 °C temperature, and 15 minutes of contact time. The adsorption of MB (methylene blue) and CV (crystal violet) dyes by Ni complex integrated MCM-48 was effective, with over 99% adsorption achieved in 15 minutes. A recyclability test was also performed, and the material is reusable up to the third cycle, with no notable decline in adsorption found. From the previous literature survey, it is clear that very high adsorption efficiency was achieved using MCM-48-SO3-Ni in considerably short contact time which proves the novelty and effectiveness of the modified material. Ni4 was prepared, characterized, and immobilized in sulfonic acid functionalized MCM-48, and this robust and reusable adsorbent was highly effective for the adsorption of methylene blue and crystal violet dyes with >99% adsorption efficiency in short duration.

Chemical recycling of plastic waste to monomers: Effect of catalyst contact time, acidity and pore size on olefin recovery in ex-situ catalytic pyrolysis of polyolefin waste

The catalytic upgrading of post-consumer mixed polyolefinic waste pyrolysis vapors has been studied over five different solid acid catalysts to understand the effect of vapor-catalyst contact time and catalyst properties on the recovery of light olefins (C2-C4). HZSM-5 with Si/Al ratio of 11 and 27 produced the highest light olefins yields (83.4 wt% and 72.1 wt%, respectively) at a very short contact time of ∼5 ms while extending the contact time (≥23 ms) decreased the olefin yields and resulted in higher yields of aromatics (∼30.0 wt% and ∼40.0 wt%, respectively). Short contact time (5 ms) was not sufficient for HZSM-22 to crack pyrolysis vapors to C2-C4 olefins (8.0 wt%) but increasing contact time improved C2-C4 yields to 53.5 wt% without increased production of aromatics, which may be attributed to its small pore size (shape selectivity). SAPO-34, SAPO-11, and Al-MCM-41 were not selective to light olefins at any studied contact time.

Influences of probe shape and surface roughness on tack properties measured by the probe tack test and characterization of crosslinked polyacrylic pressure‐sensitive adhesives

AbstractFor a probe tack test for a pressure‐sensitive adhesive (PSA) under the conditions of light contact pressure and short contact time, probes with shapes and surface roughnesses suitable to achieve better wettability were investigated. A smooth, polished probe that became slightly convex at its center was found to be superior to flat‐ended. High surface roughness decreased tack. Debonding observations showed that fibrillation started from the probe edge and extended to the center. The fibril grew, without peeling, until the peak of the force–displacement curve was reached. After the peak, the fibril growth and peeling advanced simultaneously. The fibrillation was important to tack development. The test conditions necessary to observe the deformation behavior of PSA tape with sufficient interfacial adhesion were investigated. The system was preheated at 60°C for 1 h after the probe and PSA tape contacted each other, and was then cooled. The PSA performance of crosslinked random copolymers poly(n‐butyl acrylate‐acrylic acid) (A) and poly(2‐ethylhexyl acrylate‐acrylic acid) (B) were compared. A shoulder formed by fibrillation after the peak in the force–displacement curve was observed only for B. Copolymer B exhibited better interfacial adhesion and deformability. The preheating method was found to be useful for characterizing PSAs.

Dose–response effect of incremental lateral-wedge hardness on the lower limb Biomechanics during typical badminton footwork

ABSTRACT Badminton footwork has been characterised with jump-landing, cross step, side side and lunges, which requires movement agility to facilitate on-court performance. A novel badminton shoe design with systematic increase of lateral wedge hardness (Asker C value of 55, 60, 65, and 70) was developed and investigated in this study, aiming to analyse the dose–response effect of incremental wedge hardness on typical badminton footwork. Stance time and joint stiffness were employed to investigate the footwork performance, and the factorial Statistical non-Parametric Mapping and Principal Component Analysis (PCA) were used to quantify the biomechanical responses over the stance. As reported, shorter contact times (decreased by 8.9%–13.5%) and increased joint stiffness (in side step) of foot-ankle complex were found, suggesting improved footwork stability and agility from increased hardness. Time-varying differences were noted during the initial landing and driving-off phase of cross and side steps and drive-off returning of lunges, suggesting facilitated footwork performance. The reconstructed modes of variations from PCA further deciphered the biomechanical response to the wedge dosage, especially during drive-off, to understand the improved footwork agility and stability.

Phytic Acid Demonstrates Rapid Antibiofilm Activity and Inhibits Biofilm Formation When Used as a Surface Conditioning Agent.

Root canal infections are associated with biofilms and are treated with chemical irrigants with a high success rate. However, treatment failure does arise, which is attributed primarily to resistance exhibited by biofilms. Currently used irrigants in root canal treatment have disadvantages, and there is therefore a need for more biocompatible alternatives with antibiofilm properties to reduce root canal treatment failure and complications. The aim of this study was to evaluate the in vitro antibiofilm properties of phytic acid (IP6), which is a potential alternative treatment agent. Single- and dual-species biofilms of Enterococcus faecalis and Candida albicans were developed on the well surfaces of 12-well plates and on hydroxyapatite (HA) coupons, and then exposed to IP6. In addition, selected HA coupons were preconditioned with IP6 before biofilm development. IP6 demonstrated bactericidal effects and altered the metabolic activity of biofilm cells. Confocal laser-scanning microscopy showed that IP6 caused significant and rapid reduction in live biofilm cells. At sublethal concentrations, IP6 did not alter the expression of tested virulence genes except for C. albicans hwp1, the expression of which was upregulated but not reflected by a change in hyphal transformation. IP6-preconditioned HA coupons led to extensive inhibition of dual-species biofilm formation. The results of this study highlight for the first time the antibiofilm inhibitory properties of IP6 and the potential for its exploitation in several clinical applications. IMPORTANCE Root canal infections are biofilm associated, and despite mechanical and chemical treatment procedures, infection recurrence occurs, and this is likely due to the high tolerance of associated biofilms to antimicrobials. The currently used treatment agents have several disadvantages, which necessitates the search for new improved agents. In this study, the natural chemical phytic acid was found to exhibit antibiofilm activity against established mono and dual mature biofilms over a short contact time. Most importantly, phytic acid was found to cause significant inhibition of dual-species biofilm formation when used as a surface preconditioning agent. The findings of this study identified a novel use of phytic acid as a potential antibiofilm agent that can be used in several clinical applications.

Graphene oxide/zeolitic imidazolate framework-8 nanocomposite for lead ion removal

Adsorption for heavy metal removal is extensively explored due to its economical and straightforward nature. In this study, the nanocomposites of graphene oxide (GO)/zeolitic imidazolate framework-8 (ZIF-8) adsorbents were prepared as adsorbents, with the solvent utilized was reverse osmosis (RO) water for a greener approach. Also, the synthesis was performed using the room temperature synthesis method which required less energy consumption. 10, 30, and 50 wt% GO were utilized to produce ZIF-8/GO composites of ZG1, ZG3, and ZG5, respectively. Based on the field emission scanning electron microscopy (FESEM) images, the adsorbents consisted of cubic and rhombic dodecahedron shapes of ZIF-8 grown on top and in between the layers of GO sheets. This inhibits the agglomeration nature of GO which increased the number of active sites, thus improving the lead ions adsorption capacity. From the batch tests conducted, ZG3 showed the greatest adsorption capacity of lead solution, followed by ZG5, ZG1, ZIF-8, and GO. The optimum conditions for adsorption using ZG3 were using the initial amount of lead solution of 20–100 mg/L at pH 5 to 6, and the sorbent dosage used was 10 mg. The equilibrium time obtained for lead adsorption was short, within 10 min for both ZG3 and ZG5. On the other hand, ZG1 reached equilibrium within 180, ZIF-8 within 240 min, and the longest time was GO, within 300 min. Therefore, ZG3 demonstrates a good potential as heavy metal adsorbent in wastewater treatment technology with ease of synthesis, sufficient amount of GO used, less dosage required, and shorter contact time needed.

On the Possibility of Thermokinetic Oscillations in the Reaction of Methane Oxidation on Nickel

The paper demonstrates the possibility of occurrence of thermokinetic oscillations during the methane oxidation on a nickel industrial catalyst at real values of the parameters. It is shown that reaction rate oscillations can originate under the conditions of short contact times and in the region where periodic oxidation–reduction processes do not occur. The origin of these thermokinetic oscillations is the periodic blocking of the surface with carbon and its cleaning by removing carbon from the catalyst surface.

Clear polyurethane coatings with excellent virucidal properties: Preparation, characterization and rapid inactivation of human coronaviruses 229E and SARS-CoV-2

Commercial polyurethane (PU) coating formulations have been modified with 1-(hydroxymethyl)-5,5-dimethylhydantoin (HMD) both in bulk (0.5 and 1% w/w) and onto the coatings surface as an N-halamine precursor, to obtain clear coatings with high virucidal activity. Upon immersion in diluted chlorine bleaching, the hydantoin structure on the grafted PU membranes was transformed into N-halamine groups, with a high surface chlorine concentration (40-43μg/cm2). Fourier transform infrared spectroscopy (FTIR) spectroscopy, thermogravimetric analysis (TGA), energy-dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS) and iodometric titration were used to characterize the coatings and quantify the chlorine contents of the PU membranes after chlorination. Biological evaluation of their activity against Staphylococcus aureus (Gram-positive bacteria) and human coronaviruses HCoV-229E and SARS-CoV-2 was performed, and high inactivation of these pathogens was observed after short contact times. The inactivation of HCoV-229E was higher than 98% for all modified samples after just 30 minutes, whereas it was necessary 12 hours of contact time for complete inactivation of SARS-CoV-2. The coatings were fully rechargeable by immersion in diluted chlorine bleach (2% v/v) for at least 5 chlorination-dechlorination cycles. Moreover, the performance of the antivirus efficiency of the coatings is considered as long-lasting, because experiments of reinfection of the coatings with HCoV-229E coronavirus did not show any loss of the virucidal activity after three consecutive infection cycles without reactivation of the N-halamine groups.