Short Contact Time Research Articles

Efficient defluoridation of drinking water using mesoporous magnetic malachite nanocomposites

The study evaluated the efficacy of magnetic mesoporous Malachite nanoparticles (NPs) in eliminating fluoride (F−) from drinking water. Screening experiments were conducted to gauge the F− adsorption capabilities of the synthesized material under different Fe3O4 loading conditions. Among the various nanomaterials examined, 0.25-Fe-M demonstrated optimal performance, exhibiting consistent Fe3O4 distribution with a crystal size of 16.66 nm with revealed irregular morphology exhibiting magnetic properties, a surface area of 13.595 m2/g and a pore size of 1.6574 nm. The optimized reaction conditions determined were: 10 min of contact time, a NC dose of 0.5 mg/mL, and an F− concentration of 10 mg/L. The maximum adsorption capacities recorded were 6.57 mg/g for Fe3O4 NPs and 7.87 mg/g for malachite NPs. Notably, the optimal adsorption capacity for F− removal was achieved with 0.25 Fe-M-NCs, reaching 8.44 mg/g, demonstrating superior performance compared to other NCs. The interplay between surface area, pore volume, and adsorption is intricate and contingent upon the unique properties of the adsorbent and adsorbate, with specific interactions governing the adsorption process. Furthermore, this study unveiled accelerated adsorption with shorter contact time and high adsorption capacity at the working pH.

Sustainable fluoride removal with scrap aluminum: Co-producing cryolite and hydrogen

This study presents a novel continuous process for fluoride removal and re- source recovery as cryolite, using a scrap aluminum-packed column. Efficient aluminum dissolution in hydrofluoric acid (HF) generates hydrogen gas and provides cost-saving alkalinity. The process achieves high efficiency (Al/F molar ratio of 2/6) within short Empty Bed Contact Times (15 min) and at low HF concentrations (500 mg/L). Solution pH plays a crucial role, with Al/F ratios above 1 achievable at pH below 4. The exothermic reaction requires temperature control, with a strong correlation (R²=0.99) between HF concentration and heat generation. Hydrogen production matches theoretical predictions. Cryolite synthesis was confirmed at optimized pH (5–5.5) with a 1:1 bypass ratio, achieving 98 % fluoride removal. XRD and SEM- EDS analyses verified cryolite formation. This approach offers a promising solution for industrial fluoride management, resource recovery, and clean hydrogen production.

Green synthesis of nano silver-modified date syrup 3D graphene for adsorptive removal of heavy metals from wastewater and its antibacterial efficiency

Abstract Many researchers are focusing on the eco-friendly and cost-effective green synthesis of materials for removing heavy metals from wastewater using materials made from natural sources. In this research, date syrup was used as a rich carbon source while potassium chloride particles were used as a substrate. Green synthesized silver nanoparticles modified the graphene foam to enhance its heavy metal removal and antibacterial efficiency. The morphology and structure of the graphene foam were examined using scanning electron microscopy and Raman spectroscopy. The Brunauer-Emmett-Teller method examines textural features such as surface area, pore volume and diameter. The study focused on evaluating the efficiency of removing heavy metals including cadmium, lead, zinc, and chromium from water. The results indicated that the date syrup graphene foam has high heavy metal removal efficiency despite the short contact time, especially for Cd2+ and Pb2+, with removal efficiencies of 68% and 39%, respectively. It shows a relatively lower efficacy for Zn2+ and Cr2+, with removal efficiencies of 10% and 27%, respectively. The addition of silver nanoparticles greatly improved the removal efficiency of Cd2+ (75%), Zn+2 (22%), and Cr2+ (33%). Moreover, the antibacterial efficacy test showed significant improvement after the nanosilver modification to reach a 100% bacterial-killing rate.

Sonolysis-ozonation and peroxidation method for removal of atenolol and amoxicillin in wastewater

Pharmaceutical compounds represent a significant challenge as water pollutants due to their persistence and adverse impacts on both the environment and human health. In the present study, the degradation of two pharmaceuticals- atenolol and amoxicillin was assessed in three advanced oxidation processes (AOPs), namely sonolysis, ozonation, and electrochemical peroxidation (ECP) under varying operational conditions using sewage as water matrix. The degradation of atenolol and amoxicillin was found to be over 95% at 1350W, contact time of 15min and pH of 3 during sonolysis. Ozonation proved very effective in the removal of both pharmaceuticals (>95%) in a short contact time of 30seconds using 0.32g/L-min ozone dose at pH 9. The removal of pharmaceuticals was highest at pH 9 compared to pH 4, and an ozone dosage of 0.21g/L-min was found to be adequate for achieving good degradation for both pharmaceuticals (>85%). In ECP, the maximum removal obtained for atenolol and amoxicillin was 94% and 91%, respectively, by using a current intensity of 10mA/cm2 and a hydrogen peroxide dose of 3mM. Ozonation rapidly degraded (>95%) atenolol and amoxicillin in just 30seconds, showcasing its superior performance.

Assessing the effectiveness of performic acid disinfection on effluents: focusing on bacterial abundance and diversity.

Poorly-treated wastewater harbors harmful microorganisms, posing risks to both the environment and public health. To mitigate this, it is essential to implement robust disinfection techniques in wastewater treatment plants. The use of performic acid (PFA) oxidation has emerged as a promising alternative, due to its powerful disinfection properties and minimal environmental footprint. While PFA has been used to inactivate certain microbial indicators, its potential to tackle the entire microbial community in effluents, particularly resistant bacterial strains, remains largely unexplored. The present study evaluates the efficacy of PFA disinfection on the microbial communities of a WWTP effluent, through microbial resistance mechanisms due to their membrane structure. The effluent microbiome was quantified and identified. The results showed that the number of damaged cells increases with CT, reaching a maximum for CT = 240mg/L•min and plateauing around 60mg/L•min, highlighting the optimal conditions for PFA-disinfection against microbial viability. A low PFA level with a 10-min contact time significantly affected the microbial composition. It is worth noting the sensitivity of several bacterial genera such as Flavobacterium, Pedobacter, Massilia, Exiguobacterium, and Sphingorhabdus to PFA, while others, Acinetobacter, Leucobacter, Thiothrix, Paracoccus, and Cloacibacterium, showed resistance. The results detail the resistance and sensitivity of bacterial groups to PFA, correlated with their Gram-positive or Gram-negative membrane structure. These results underline PFA effectiveness in reducing microbial levels and remodeling bacterial composition, even with minimal concentrations and short contact times, demonstrating its suitability for widespread application in WWTPs.

Zeolite-modified alumina-bead catalyst for hierarchical cracking of bulky molecules

A novel zeolite-modified alumina-bead catalyst (ZSM-5/Al2O3-b) was prepared via calcining zeolite-coated alumina-bead material (Al2O3-b@ZSM-5) to graft zeolitic acid sites on the alumina-bead surface. The acid catalyst proved high activity and more 8 times catalytic efficiency than the corresponding ZSM-5(5 %) + Al2O3 mechanically mixed catalyst for cracking of 1, 3, 5-triisopropylbenzene (TIPB) in the FCC simulation reactor with short contact time. The characterization results showed that the surface property of the alumina-beads has been modified and the interface connection of Si-O-Al bonds between zeolitic nanoparticles and alumina resulted in stable zeolite particles on the alumina surface and the structural stability in hot water. The excellent catalytic performances are ascribed to the decrease of diffusion limitation of reactants and intermediates and the increase of Brønsted acid sites on the ZSM-5/Al2O3-b catalyst. The grafted/modified alumina-bead catalyst can be directly used in practical catalytic cracking of large molecules without forming. This strategy can be extended to the preparation of other types of zeolite-containing catalysts and industrial applications.

Removal of Trace Cu2+ from Water by Thermo-Modified Micron Bamboo Charcoal and the Effects of Dosage

Chronic copper intoxication via drinking water induces diseases and physiological toxicity. Bamboo charcoal has been applied in the treatment of copper (Cu2+) in water. However, the adsorption by micron bamboo charcoal (MBC) of trace Cu2+ in tap drinking water and the underlying factors behind it have not been sufficiently reported. In this study, to improve the adsorption by MBC of trace levels of Cu2+ in drinking water, MBC was thermo-modified and characterized. Through batch experiments, the adsorption equilibrium was analyzed, and isotherm models were simulated. The removal rates and the optimization were investigated through a general full factorial design including the thermo-modified temperature (MT), initial concentration (C0), and dosage. The results indicated that the thermo-modification significantly improved the removal by MBC of Cu2+ at trace level C0. The satisfactorily low level of 0.12 ± 0.01 mg⋅L−1 was achieved in the range of C0 from 0.5 to 2.0 mg⋅L−1 within the short contact time of 0.5 h. The processes conformed to the Freundlich and Langmuir adsorption isothermal models at a C0 lower than 4.0 mg⋅L−1 and higher than 8.0 mg⋅L−1. The correlation between C0 and dosage played an important role in the removal of Cu2+. This work proposes the application of the ecofriendly material MBC and an optimization mode in the removal of trace Cu2+ from tap drinking water. It is also revealed that the positive and negative correlation and the “critical point” of the removal rate with dosage depend on the initial concentrations.

Carbon-Based Materials in Combined Adsorption/Ozonation for Indigo Dye Decolorization in Constrain Contact Time.

This study presents a comprehensive evaluation of catalytic ozonation as an effective strategy for indigo dye bleaching, particularly examining the performance of four carbon-based catalysts, activated carbon (AC), multi-walled carbon nanotubes (MWCNT), graphitic carbon nitride (g-C3N4), and thermally etched nanosheets (C3N4-TE). The study investigates the efficiency of catalytic ozonation in degrading Potassium indigotrisulfonate (ITS) dye within the constraints of short contact times, aiming to simulate real-world industrial wastewater treatment conditions. The results reveal that all catalysts demonstrated remarkable decolorization efficiency, with over 99% of indigo dye removed within just 120 s of mixing time. Besides, the study delves into the mechanisms underlying catalytic ozonation reactions, elucidating the intricate interactions between the catalysts, ozone, and indigo dye molecules with the processes being influenced by factors such as PZC, pKa, and pH. Furthermore, experiments were conducted to analyze the adsorption characteristics of indigo dye on the surfaces of the materials and its impact on the catalytic ozonation process. MWCNT demonstrated the highest adsorption efficiency, effectively removing 43.4% of the indigo dye color over 60 s. Although the efficiency achieved with C3N4-TE was 21.4%, which is approximately half of that achieved with MWCNT and less than half of that with AC, it is noteworthy given the significantly lower surface area of C3N4-TE.

Time-dependent underwater interaction between polyhydroxyalkanoate coatings and functionalized surfaces

Polyhydroxyalkanoates (PHAs), a family of naturally occurring biodegradable polyester, are considered environmentally friendly alternatives to conventional commodity plastics derived from petrochemicals.; however, their molecular interaction in water has not been elucidated. Here, we investigated the surface- and contact time-dependent underwater interaction characteristics of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB-co-4HB)), the most common PHA, using a surface forces apparatus (SFA). We found that PHA showed weak adhesion with functionalized surface and cohesion for a short-contact time (<30 mins) in the water. The adhesion to the functionalized surface was strong in the order of mica (negatively charged hydrophilic), APTES (positively charged hydrophilic), and PS (hydrophobic). However, the adhesive strength of PHA to the functionalized surfaces increased as contact time increased, which may be attributed to chain rearrangement, reorientation, or van der Waals forces of PHA in water. We also confirmed results similar to those for SFA by bulk testing on hydrophilic surfaces. As PHAs have attracted people’s attention as eco-friendly and biocompatible polymers, these results provide insights for the development of PHA-based composite, as well as for the biodegradation and fate of PHA post-use.

Calculation of the Rate Constants of Vacuum Residue Hydrogenation Reactions in the Presence of a Chrysotile/NiTi Nanocatalyst

The paper presents the results of an investigation into the kinetics of catalytic hydrogenation of vacuum residue at temperatures of 380, 400 and 420 °C and different durations, ranging from 30 to 70 min, using a nanocatalyst containing the active metals nickel and titanium supported on chrysotile. It was found that the yield of oils from 30 to 50 wt.% and tars from 12 to 18 wt.% increased with increasing temperatures and reaction times. A slight increase in the proportion of solids in the range of 2.0 to 6.0 wt.% is explained by the activity of the nanocatalyst used. In the study of the kinetics of vacuum residue hydrogenation, using the nanocatalyst developed by the authors, we were able to achieve a low yield of solids with a short contact time as well as a high yield of low-molecular-weight compounds such as oils and tars. To determine the kinetic parameters (rate constants and activation energies), Simpson’s integral method and a random search engine optimization method were used. High values of rate constants are characteristic of reactions in the formation of oils k1, tars k2 and asphaltenes k3 in the temperature range of 380–420 °C. The high values of the rate constants k1, k2 and k3 in the catalytic hydrogenation of the vacuum residue indicate the high reaction rate and activity of the nanocatalyst used. With an increase in temperature from 380 to 420 °C, the rate constant of the formation of gas products from vacuum residue and the conversion of asphaltenes into oils significantly increase, which indicates the accumulation of low-molecular-weight compounds in oils. The activation energy for reactions leading to the formation of oils, tars, asphaltenes, gas and solid products was 75.7, 124.8, 40.7, 205.4 and 57.2 kJ/mol, respectively. These data indicate that the processes of vacuum residue hydrogenation with the formation of oils and asphaltenes require the lowest energy inputs. Reducing the process temperature to increase the selectivity of the vacuum residue hydrogenation process when using the prepared nanocatalyst is recommended. The formation of oils at the initial stage plays a key role in the technology of the heavy hydrocarbon feedstock (HHF) hydrogenation process. Perhaps the resulting oils can serve as an additional solvent for high-molecular-weight products such as asphaltenes, as evidenced by the low activation energy of the process.

The Effective Separation of Gallium, Vanadium, and Aluminum from a Simulated Bayer Solution by Resin Exchange.

The effective recovery of gallium from wastewater discharge in the Bayer process is promising for the long-term development of gallium resources. The adsorption and desorption behavior of gallium (Ga), vanadium (V), and aluminum (Al) ions on a strong acidic styrene cation exchange resin (JK resin) from a simulated Bayer solution was systematically investigated by static experiments. The results showed that the optimum conditions for separating Ga from V and Al were at low temperatures and short contact times, with 78.30%, 15.16%, and 6.63% of the adsorption efficiency at 25 °C and 60 min, respectively, for Ga, V, and Al. The adsorption kinetics of Ga3+ conformed to the pseudo-second order model, and the static saturation adsorption capacity was 18.25 mg/g. The Langmuir model fitted the adsorption isotherm of gallium well, and the maximum adsorption capacity was 1.11 mg/g at 25 °C. FT-IR spectroscopy and XPS showed that the mechanism of the Ga3+ adsorption was only related to the interaction of the oxygen atoms of the amide oxime group (C=NOH). The separation of Ga, V, and Al can be achieved by desorbing 98% of Al with low concentrations of ammonia and 90% of Ga with low concentrations of hydrochloric acid. The results indicate that JK resin is an efficient adsorbent for separating gallium and vanadium in alkaline solutions.

Preparation of CMC-MF/FeO(OH) by growing ferric nanoparticles on melamine foam in-situ for effective phosphate removal

Nanocomposite adsorbents composed of a bulk matrix and metal nanoparticles have garnered significant attention for phosphorus (P) removal. However, many nanocomposite adsorbents have been synthesized in harsh environments involving high temperature or high energy consumption, which do not meet industrial requirements; on the other hand, lots of adsorbents are synthesized by directly depositing metal hydroxides on bulk matrixs, leading to the active components shedding from the matrix due to the lack of chemical anchoring sites to immobilize metal oxide. To overcome the limitations of the existing methods, we synthesized a nanocomposite adsorbent named CMC-MF/FeO(OH) using a facile method in a mild environment. It involved coating an anchoring film prepared with carboxymethyl cellulose sodium (CMCNa) on melamine foam (MF) for in-situ growth of ferric nanoparticles. Our results demonstrated that the CMC-MF/FeO(OH) adsorbent showed promising efficiency in phosphate removal. The adsorption process was effectively described by Elovich kinetic model and Freundlich isotherm model. The adsorption mechanism was ascribed to the chemisorption by inner-sphere complex along with physical adsorption. A maximum adsorption capacity of 31.579 mg P/g which calculated by Langmuir isotherm model was achieved at 45 °C and natural pH condition in experimental range. The adsorbent exhibited effective P adsorption even in harsh environments, with the process being spontaneous and exothermic. In column applications, the CMC-MF/FeO(OH) adsorbent reduce the P content of wastewater from 4 mg P/L to 0.5 mg P/L within a short empty bed contact time of 190.95 s. Furthermore, the adsorption capacity reached 8.87 mg P/g in a column study, and trace P levels in lake water decreased to undetectable levels in a lake experiment, effectively inhibiting algae growth.

ECMSH: An Energy-efficient and Cost-effective data harvesting protocol for Mobile Sink-based Heterogeneous WSNs using PSO-TVAC

Efficient energy consumption is crucial in Wireless Sensor Networks (WSNs). Uncontrolled energy usage can lead to the hotspot issue, hindering network lifetime and successful packet delivery. Sink mobility has been suggested as a solution, but it comes with challenges such as high data gathering delay and poor packet reception. These problems stem from the short contact time of nodes with the Mobile Sink (MS). To tackle these issues, we present an MS-based heterogeneous WSN with super and normal nodes. Most previous studies only considered the energy heterogeneity of sensors. These methods also suffered from different issues such as fixed MS tours, including inappropriate criteria in cluster construction, proposing greedy schemes, and employing basic metaheuristic algorithms. In our proposed model, super nodes are richer in initial energy and transmission range than normal sensors. In each round, the nodes are organized into clusters, and the MS visits the Cluster Heads (CHs) to gather data packets. Super nodes, owing to their elevated initial energy, are more adept at executing energy-sensitive tasks compared to normal sensors. Additionally, as CH, super nodes extend the contact time with the MS due to their longer transmission range, delivering more packets. The clusters are constructed using a variant of Particle Swarm Optimization (PSO), namely PSO-TVAC. We empower this method with effective initialization and decoding methods. Furthermore, we propose a heuristic intra-cluster multi-hop routing algorithm to enhance network lifetime. Our other contribution is to propose an efficient algorithm to determine the time to reconfigure the network, while the other algorithms mainly reconfigure the WSN periodically. Simulation results demonstrate superior performance compared to state-of-the-art algorithms, showcasing lower energy consumption, higher energy efficiency, higher lifetime, reduced packet delivery delay, and higher number of received packets by 30%, 38.2%, four times, 20.6%, and 22.6%, respectively.

Enhancing and sustaining arsenic removal in a zerovalent iron-based magnetic flow-through water treatment system

In areas affected by arsenicosis, zerovalent iron (ZVI)/sand filters are extensively used by households to treat groundwater, but ZVI surface passivation and filter clogging limit their arsenic (As) removal performance. Here we present a magnetic confinement-enabled column reactor coupled with periodic ultrasonic depassivation (MCCR-PUD), which efficiently and sustainably removes As by reaction with continuously generated iron (oxyhydr)oxides from ZVI oxidative corrosion. In the MCCR, ZVI microparticles self-assemble into stable millimeter-scale wires in forest-like arrays in a parallel magnetic field (0.42−0.48 T, produced by two parallel permanent magnets), forming a highly porous structure (87 % porosity) with twice the accessible reactive surface area of a ZVI/sand mixture. For a feed concentration of 100 μg/L As(III), the MCCR-PUD, with a short empty bed contact time (1.6 min), treated ca. 7340 empty bed volume (EBV) of water at breakthrough (10 μg/L), 9.4 folds higher than that of a ZVI/sand filter. Due to the large interspace between ZVI wires, the MCCR-PUD effectively prevented column clogging that occurred in the ZVI/sand filter. The high water treatment capacity was attributed to the much enhanced ZVI reactivity in the magnetic field, sustained through rejuvenation by PUD. Furthermore, most of As was structurally incorporated into the produced iron (oxyhydr)oxides (mostly ferrihydrite) in the MCCR-PUD, as revealed by Mössbauer spectroscopy, X-ray absorption spectroscopy, and sequential extraction experiments. This finding evinced a different mechanism from the surface adsorption in the ZVI/sand filter. The structural incorporation of As also resulted in much less As remobilization from the produced corrosion products during aging in water, in total ∼1 % in 28 days. Furthermore, the MCCR-PUD exihibted robust performance when treating complex synthetic groundwater containing natural organic matter and common ions (∼3700 EBV at breakthrough). Taken together, our study demonstrates the potential of the magnetic confinement-enabled ZVI reactor as a promising decentralized As treatment platform.

Adsorptive removal of phosphate from water with biochar from acacia tree modified with iron and magnesium oxides

A novel biochar (BC) from Acaciatortilis trees pruning waste was synthesized and tested for the removal of phosphate from aqueous solutions. The BC was prepared by calcination at 600 °C and doped with Fe3O4 and MgO by hydrothermal process. The presence of iron and magnesium ions in the modified BC was confirmed by EDS analysis and X-ray diffraction (XRD) methods. Both unmodified and doped BCs were tested for phosphate removal from synthetic 1–500 ppm aqueous solutions. While the unmodified BC did not show any significant removal of phosphate from aqueous solutions, the modified BC almost completely removed phosphate from water. The enhancement in removal efficiency is due to an increase in the overall surface charge and surface area of BC as a result of doping with Fe3O4 and MgO salts. The average porosity and BET surface area corresponding to the plain BC increased by more than 20% from 322 to 394 m2/g after modification by impregnation with iron oxide and magnesium oxide. The modificaiton of BC with Fe3O4 and MgO nanoparticles was observed to increase the point of zero electric charge (PZC) from pH 3.4 (corresponding to plain BC) to pH 5.3 (corresponding to modified BC). The adsorption process was very fast and a phosphate removal value of 82.5% was reached only after 30 min of adsorption, while the removal efficiency after 4 h of adsorption was 97.5%. The rapid removal efficiency in short contact time is attributed to the high surface area of BC and strong bonding between the modified BC surface and PO43− ions. The highest adsorption capacity was observed to correspond to 98.5 mg/g which was achieved at PO43− concentration of 500 ppm and pH 8.5. Moreover, after fitting the adsorption data onto four of the most widely used adsorption isotherm models, the adsorption of PO43− onto BC can be better described by the Langmuir isotherm model.

Novel boehmite and η-alumina nanostructures synthesized using a green ultrasonic-assisted hydrothermal method by clove extract for water treatment

In the paper, a novel three-dimensional self-assembly flower-like structure consisting of one-dimensional needle-like η-alumina as well as spherical boehmite and η-alumina nanoparticles synthesized through the green ultrasonic-assisted hydrothermal method (GUAH) is introduced. Also, the effects of clove extract and calcination of nanoparticles (NPs) at 550 °C on the properties of the NPs are studied. The results declare that the extract concentration and calcination affect the crystallinity of the NPs, and amorphous NPs are formed at a higher concentration of clove extract. Notably, the extract concentration predominantly impacts the optical properties of the NPs, yielding a wide range of bandgap energies from 2.3 to 4.7 eV. Moreover, the specific surface area of 173 to 330 m2/g, and 195 to 327 m2/g are obtained for boehmite and η-alumina NPs, respectively. Evaluating the efficiencies of the NPs in treating water containing copper ions (194 ppm) under varying pH conditions demonstrates high removal rates at short contact times (10 min) achieved by specific η-alumina NPs as a good candidate for water treatment from Cu2+ ions.

Impacts of Wearable Resistance Placement on Running Efficiency Assessed by Wearable Sensors: A Pilot Study.

Wearable resistance training is widely applied to enhance running performance, but how different placements of wearable resistance across various body parts influence running efficiency remains unclear. This study aimed to explore the impacts of wearable resistance placement on running efficiency by comparing five running conditions: no load, and an additional 10% load of individual body mass on the trunk, forearms, lower legs, and a combination of these areas. Running efficiency was assessed through biomechanical (spatiotemporal, kinematic, and kinetic) variables using acceleration-based wearable sensors placed on the shoes of 15 recreational male runners (20.3 ± 1.23 years) during treadmill running in a randomized order. The main findings indicate distinct effects of different load distributions on specific spatiotemporal variables (contact time, flight time, and flight ratio, p ≤ 0.001) and kinematic variables (footstrike type, p < 0.001). Specifically, adding loads to the lower legs produces effects similar to running with no load: shorter contact time, longer flight time, and a higher flight ratio compared to other load conditions. Moreover, lower leg loads result in a forefoot strike, unlike the midfoot strike seen in other conditions. These findings suggest that lower leg loads enhance running efficiency more than loads on other parts of the body.

Recycling polyolefin plastic waste at short contact times via rapid joule heating

The chemical deconstruction of polyolefins to fuels, lubricants, and waxes offers a promising strategy for mitigating their accumulation in landfills and the environment. Yet, achieving true recyclability of polyolefins into C2-C4 monomers with high yields, low energy demand, and low carbon dioxide emissions under realistic polymer-to-catalyst ratios remains elusive. Here, we demonstrate a single-step electrified approach utilizing Rapid Joule Heating over an H-ZSM-5 catalyst to efficiently deconstruct polyolefin plastic waste into light olefins (C2-C4) in milliseconds, with high productivity at much higher polymer-to-catalyst ratio than prior work. The catalyst is essential in producing a narrow distribution of light olefins. Pulsed operation and steam co-feeding enable highly selective deconstruction (product fraction of >90% towards C2-C4 hydrocarbons) with minimal catalyst deactivation compared to Continuous Joule Heating. This laboratory-scale approach demonstrates effective deconstruction of real-life waste materials, resilience to additives and impurities, and versatility for circular polyolefin plastic waste management.

Filtered handheld far-ultraviolet disinfection device in reducing environmental pathogens from high-touch clinical surfaces

Background: Healthcare-acquired infections (HAIs) continue to be a major challenge. In fact, an increased risk of HAIs has been linked to high-touch surfaces contaminated with multidrug-resistant organisms (MDROs), and enhanced environmental disinfection is linked to reduced HAI rates. Recently, more focus has been placed on emerging disinfection technologies, such as UV light-producing portable device that emits light at a wavelength of 222 nm, which has previously demonstrated germicidal capabilities at short contact times. In this study, we aim i) to evaluate the efficacy of a filtered far-UV-C handheld device (FFUHH) to reduce bacterial loads on high-touch surfaces in clinical workrooms in a cancer center, and ii) to isolate, identify and establish a genetic relationship between these environmental clinically significant pathogens and the ones recovered from patients. Methods: Samples were collected weekly on a rotating schedule over a 24-week period from five high-touch items (dictation device, mouse, armchair, desk, and keyboard) in multiple clinical work rooms on hematologic malignancy and stem cell transplant units. Contact plates for colony count and swabs were collected pre- and post-intervention with the FFUHH on standardized adjacent areas respectively for each surface. The swabs were enriched and cultured on selective media to isolate clinically significant pathogens. Whole genome sequencing (WGS) was then performed on environmental pathogens validated by MALDI-TOF as well as clinical samples collected from patients in the same unit around the time of environmental sample collection. Results: A total of 440 plates, 220 pre- and 220 post-interventions, were collected and analyzed. The highest mean colony count pre-treatment was detected from the armchairs and the lowest for the keyboards. The mean reduction of colony forming units (CFUs) ranged between 53% for the keyboard and 83% for the mouse. The reduction was statistically significant across all surfaces with P values &lt; 0.05, except for the keyboard (Figure 1). We isolated many pathogens of the human microbiota identified by MALDI-TOF such as Micrococcus luteus, S. capitis as well as methicillin-resistant S. epidermidis, S. haemolyticus and S. hominis. We also identified several Candida parapsilosis, Pseudomonas stutzeri, one Listeria grayi and one Acinetobacter baumanni. Finally, WSG allowed us to further characterize an environmental multi-drug resistant S. epidermidis ST5 strain associated with patient bacteremia, and ST16 strains detected on surfaces both pre- and post-FFUHH treatment. Conclusion: The FFUHH effectively reduced the microbial burden on high-touch surfaces in clinical workrooms on hematologic malignancy and stem cell units.

Experimental analysis of the kinematics in the elastic collision between two bodies during the contact time

The elastic collision between two bodies is a fleeting event challenging to observe due to its infinitesimally short contact time, usually lasting mere hundredths or even thousandths of a second. This brief duration poses significant challenges for accurately measuring velocities and impulsive forces and establishing representative functions. Consequently, this study aims to address these challenges. Experimental measurements of velocity, acceleration, and force changes during the contact period are crucial for validating theoretical models and functions that accurately represent the dynamics of collisions under realistic conditions. These measurements are critical in optimizing the activation response of airbag and restraint systems in vehicles and are fundamental in reconstructing physical scenarios of accidents. The experiments were conducted in a practical computer-assisted laboratory, utilizing wireless sensors embedded within the test vehicles and positioned on a low-friction track. The collision setup was designed to be horizontal and frontal, ensuring that the bodies involved did not undergo permanent deformations. The primary methodology adopted in this analysis integrates both quantitative and qualitative approaches, focusing on collecting and analyzing numerical data to identify patterns and establish mathematical relationships between variables. This integrated approach offers a more comprehensive understanding of the kinematics of colliding vehicles during the contact period.