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The 'gas‒liquid‒solid' mechanism annealing method was used to create a superhydrophobic boron nitride nanotube (BNNT) stainless steel mesh in a tube furnace at 1250 °C in an NH3 environment. Fe powder was used as a catalyst, and B:B2O3 = 4:1 was used as the raw material. The water droplets on the surface of the superhydrophobic material had a contact angle of approximately 150° and a slide angle of approximately 3°. By using molecular dynamics (MD) simulation technology, a three-dimensional braided physical model of nanodroplets and superhydrophobic BNNT mesh surfaces with the same contact angle and rolling angle was prepared via the function weaving method. The Weber number (We) was used as the entrance point to establish the relationship between macroscale experimental studies and nanoscale MD simulation analysis on the basis of these efforts. A study was conducted on the dynamic behaviour of droplets impacting a superhydrophobic BNNT filter surface. We suggest that the wettability, substrate structure, and impact velocity are connected to the impact dynamic behaviour of droplets on the basis of the data obtained at various scales. The findings demonstrate that when the droplet impact velocity increases, several droplet phenomena—such as impact–rebound, impact–spread–rebound, and impact–spread–breaking–polymerisation–spatter—appear on the substrate surface sequentially. The mechanism of impact behaviour at various scales is explained in light of these events. Furthermore, a better theoretical model is proposed to assess the droplet wetting transition at the nanoscale. This model accurately predicts the boundary Weber number that starts the wetting transition. Moreover, the connections among the impact velocity, spreading diameter, and contact time (or We) are examined. The tendencies found via MD simulations match the outcomes of the experiments. Our discoveries and outcomes broaden our understanding of how droplet impact affects the dynamic behaviour of superhydrophobic surfaces. A scientific foundation for examining the dynamic behaviour of droplets is provided by combining simulations and experiments. [ABSTRACT FROM AUTHOR]

Copyright of Industrial Minerals & Processing / Huagong Kuangwu yu Jiagong is the property of Industrial Minerals & Processing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

AbstractContinuous processes in most applications are measured discretely with error. This complicates the task of detecting intersections and the number of intersections between two continuous processes (i.e., when the processes have the same value). Intersections of continuous processes are scientifically important, but challenging to estimate from data. For example, in the field of animal ecology, intersections of the paths of moving animals tracked with satellite technologies can be used to understand disease transmission. We illustrate how to quantify contact between animals using telemetry data (i.e., the recorded locations of an animal over time). We introduce our method to quantify contact time with accessible concepts from introductory stochastic process literature, such as Brownian motion. Then, we provide two data examples using white-tailed deer (Odocoileus virginianus) and mule deer (Odocoileus hemionus) telemetry data in a region with high prevalence of chronic wasting disease. Our work provides a needed connection between existing model-based literature for animal movement and rule-based literature for animal interaction. Further, our work illustrates a unique statistical problem receiving minimal attention with broad applicability in human and livestock tracking. Supplementary materials for this article are available online. [ABSTRACT FROM AUTHOR]

Abstract The ‘gas‒liquid‒solid’ mechanism annealing method was used to create a superhydrophobic boron nitride nanotube (BNNT) stainless steel mesh in a tube furnace at 1250 °C in an NH3 environment. Fe powder was used as a catalyst, and B:B2O3 = 4:1 was used as the raw material. The water droplets on the surface of the superhydrophobic material had a contact angle of approximately 150° and a slide angle of approximately 3°. By using molecular dynamics (MD) simulation technology, a three-dimensional braided physical model of nanodroplets and superhydrophobic BNNT mesh surfaces with the same contact angle and rolling angle was prepared via the function weaving method. The Weber number (We) was used as the entrance point to establish the relationship between macroscale experimental studies and nanoscale MD simulation analysis on the basis of these efforts. A study was conducted on the dynamic behaviour of droplets impacting a superhydrophobic BNNT filter surface. We suggest that the wettability, substrate structure, and impact velocity are connected to the impact dynamic behaviour of droplets on the basis of the data obtained at various scales. The findings demonstrate that when the droplet impact velocity increases, several droplet phenomena—such as impact–rebound, impact–spread–rebound, and impact–spread–breaking–polymerisation–spatter—appear on the substrate surface sequentially. The mechanism of impact behaviour at various scales is explained in light of these events. Furthermore, a better theoretical model is proposed to assess the droplet wetting transition at the nanoscale. This model accurately predicts the boundary Weber number that starts the wetting transition. Moreover, the connections among the impact velocity, spreading diameter, and contact time (or We) are examined. The tendencies found via MD simulations match the outcomes of the experiments. Our discoveries and outcomes broaden our understanding of how droplet impact affects the dynamic behaviour of superhydrophobic surfaces. A scientific foundation for examining the dynamic behaviour of droplets is provided by combining simulations and experiments.

Background and Study Aim. Sprinting performance is crucial in many sports, and even marginal improvements in sprint mechanics can provide significant competitive advantages. The aim of this study is to examine the influence of step distance, contact time, and flight time on sprint speed. Material and Methods. The study was conducted on 26 athletes (20 males and 6 females). Body composition was measured using a bioimpedance analysis device. Sprint kinematics (step distance, contact time, and flight time) and sprint speed parameters were assessed using an optical measurement system during a 30-meter sprint test. Multiple linear regression analysis was employed to determine the effects of sprint kinematic parameters on sprint speed, as well as the effects of body composition parameters on sprint kinematics and speed. The linear regression models included one dependent variable and three independent variables. Results. Linear regression analysis revealed that step distance, contact time, and flight time were significant predictors of sprint speed, with the exception of the first step of sprint running (p < 0.05). Furthermore, the effects of body composition parameters (age, body weight, and height) on sprint kinematics and speed were found to be significant (p < 0.05). The proportions of variance explained by body composition parameters were highest for step distance and sprint speed, with R2 values of 0.719 and 0.686, respectively. Conclusions. This study confirms that step distance, contact time, and flight time are significant predictors of sprint speed. Additionally, the results underscore the substantial influence of body composition parameters such as age, body weight, and height on sprint kinematics and speed. These findings highlight the importance of considering both kinematic and physiological factors in the training and development of athletes for optimized sprint performance.

When a water drop is impinged upon a superhydrophobic surface with submillimetric surface structures, unconventional impact dynamics such as pancake-like bouncing and asymmetric drop spreading can occur. However, the fabrication of such surface structures often requires an unconventional fabrication approach, which is either time-consuming or costly. In this study, we propose a simple lithography-based approach to manufacture submillimetric cone-shaped pillars over a large area by taking advantage of a unique optical property of hydrogels: a change of refractive index after UV-curing. With an additional hydrophobic nanoparticle coating, we demonstrate that such structures can be used to reduce the contact time during drop impact and induce a drop rotation during rebound. Moreover, the flexibility of hydrogels enables the transfer of surface structures to non-planar substrates. [ABSTRACT FROM AUTHOR]

Dry reforming of methane (DRM) reaction is advantageous in producing syngas with a low H2/CO, relevant to many industries. Effect of contact time on catalytic activity and carbon deposition is studied for DRM using Ni−Al catalysts, along with the effect of metal loading, reaction temperature, and reactant partial pressure (CO2/CH4). Maximum CH4 conversion (58 %) and CO2 (59 %) were achieved at a higher contact time of 4.009 kg‐cat. h/kgCH4. A maximum of 46 % CH4 conversion was achieved at 1023 K with a contact time of 0.134 kg‐cat. h/kgCH4. Higher CH4 and CO2 conversion were achieved with an excellent H2 and CO yield due to the RWGS reaction with increased metal (Ni) loading (10–30 wt. %). When the reactant partial pressure (CO2) changed from 0.1–0.3, the CH4 conversion increased whereas CO2 conversion decreased. FESEM images revealed the formation of whisker‐like carbon fibers for all loadings. For the best syngas output and stability in a Ni‐based catalyst, a combination of a basic support (alumina) at a higher contact time (~4.009 kg‐cat. h/kgCH4) and a CO2/CH4 ratio of 1–1.5 at a moderate temperature of 873 K may provide best CO2 adsorption with minimal coking. [ABSTRACT FROM AUTHOR]

Background and Study Aim Sprinting performance is crucial in many sports, and even marginal improvements in sprint mechanics can provide significant competitive advantages. The aim of this study is to examine the influence of step distance, contact time, and flight time on sprint speed. Material and Methods The study was conducted on 26 athletes (20 males and 6 females). Body composition was measured using a bioimpedance analysis device. Sprint kinematics (step distance, contact time, and flight time) and sprint speed parameters were assessed using an optical measurement system during a 30-meter sprint test. Multiple linear regression analysis was employed to determine the effects of sprint kinematic parameters on sprint speed, as well as the effects of body composition parameters on sprint kinematics and speed. The linear regression models included one dependent variable and three independent variables. Results Linear regression analysis revealed that step distance, contact time, and flight time were significant predictors of sprint speed, with the exception of the first step of sprint running (p < 0.05). Furthermore, the effects of body composition parameters (age, body weight, and height) on sprint kinematics and speed were found to be significant (p < 0.05). The proportions of variance explained by body composition parameters were highest for step distance and sprint speed, with R2 values of 0.719 and 0.686, respectively. Conclusions This study confirms that step distance, contact time, and flight time are significant predictors of sprint speed. Additionally, the results underscore the substantial influence of body composition parameters such as age, body weight, and height on sprint kinematics and speed. These findings highlight the importance of considering both kinematic and physiological factors in the training and development of athletes for optimized sprint performance. [ABSTRACT FROM AUTHOR]

Copyright of Ingenius, Revista Ciencia y Tecnología is the property of Universidad Politecnica Salesiana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revija Šport is the property of Sport: Revija Za Teoreticna in Praticna Vprasanja Sporta and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Applied Mechanics is the property of Chinese Journal of Applied Mechanics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Running poses a high risk of developing running-related injuries (RRIs). The majority of RRIs are the result of an imbalance between cumulative musculoskeletal load and load capacity. A general estimate of whole-body biomechanical load can be inferred from ground reaction forces (GRFs). Unfortunately, GRFs typically can only be measured in a controlled environment, which hinders its wider applicability. The advent of portable sensors has enabled training machine-learned models that are able to monitor GRF characteristics associated with RRIs in a broader range of contexts. Our study presents and evaluates a machine-learning method to predict the contact time, active peak, impact peak, and impulse of the vertical GRF during running from three-dimensional sacral acceleration. The developed models for predicting active peak, impact peak, impulse, and contact time demonstrated a root-mean-squared error of 0.080 body weight (BW), 0.198 BW, 0.0073 BW ⋅ seconds, and 0.0101 seconds, respectively. Our proposed method outperformed a mean-prediction baseline and two established methods from the literature. The results indicate the potential utility of this approach as a valuable tool for monitoring selected factors related to running-related injuries.

The primary goal of the current research was predicting the optimum operational parameters for removing of Fe (II) from aqueous solutions by Exhausted Coffee Husk (ECH) biochar, through batch mode experiments using a Box-Behnken Design (BBD) within a Response Surface Methodology (RSM) framework. The effect operational factors for instance, pH, contact time and the dosage of ECH-biochar were investigated in a certain range, prior to conducting the BBD experiments. The pH was in a range of 4–9, while the contact time was in between 30 and 150 minutes and the dosage 0.05–2.5 g. The results showed that the optimum operational parameters for ECH biochar as biosorbent for Fe ions removal were 7, 0.102 g, 54.49 minutes for pH, contact time and dosage, respectively, with the RE and biosorption capacity (qt) were 99.91 % and 73.09 mg/g. The validation test showed the similar results were obtained for RE and qt with %RSD were 0.7 %. The process of Fe biosorption corresponds effectively with a modified Langmuir isotherm model, and the prediction of the rate constant is reliably achieved using the pseudo-second-order kinetic model. Furthermore, analyses of scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) and X-ray diffraction (XRD) showed ion exchange as the Fe removal mechanism by the ECH-BC, while Fourier-transform infrared spectroscopy (FT-IR) also showed the role of structural alterations on the surface of ECH-BC subsequent to the biosorption of Fe.

The aim of this study was to investigate the hold-by-hold climbing fluency dynamics by using an instrumented holds system that measured the contact time on each hold. Forty-four competitive climbers have been analysed in a regional lead climbing competition during a route composed of 41 instrumented holds on 11 m high artificial climbing wall and with a grade of difficulty 6b on the French scale (IRCRA reported scale: 13). After removing 10 climbers who fell before the top of the route, the 34 remaining climbers who completed the route were clustered according to their total contact time on each hold. The hierarchical cluster analysis distinguished four profiles of climbing fluency dynamics, on the basis of six 'crux' points, showing that the fastest climbers at the crux points were those with the shortest climbing time. This new instrumented-holds system appeared very innovative as it provides an instantaneous feedback to coaches regarding inter-limbs fluency and subsequent motor organisations. [ABSTRACT FROM AUTHOR]

Gait mechanics alternation is one of side effects after anterior cruciate ligament reconstruction (ACLR). Foot roll-off characteristics shows whole gait mechanics and is not well known in ACLR patients. The purpose of present study was to investigate the roll-off process characteristics while walking and running in patients with ACLR history. Is there any difference in walking and running roll-off characteristics between patients with ACLR history and healthy individuals? 48 physically active males (24 healthy and 24 with ACLR history) participated in this study. Participants walked and ran on a footscan (Rsscan International) which was mounted in the midway of a 18 m runway at the speeds of 2 m·s−1 and 3.3 m·s−1. Center of pressure (COP) trajectory, timing of stance subphases, foot progression angle and contact time were calculated bilaterally in walking and running. Mixed-design MANOVA was used to examine effect of ACLR on the outcomes. The results showed that ACLR participants had greater foot progression angle (p =.001) and more medially oriented COP trajectory in forefoot push-off phase (FFPOP) of waking (p =.001) and running (p =.001), but showed shorter contact time in running compared to healthy group (p =.02). Involved leg in ACLR group showed greater foot progression angle (p =.001) and more medially directed COP trajectory in FFPOP of walking (p =.001) and running (p =.01) compared to uninvolved side. Also, involved leg had shorter contact time (p =.04) and shorter relative time in the forefoot contact phase (p =.001), and longer relative time in forefoot flat phase (p =.001) during running. Based on the results, it can be concluded that ACLR affects running and walking roll-off characteristics which can show altered mechanics. Running shows remarkable differences in roll-off process than walking. So, it is recommended to use running in post-ACLR assessments rather than walking. • ACLR patients show altered roll-off patterns in walking and running. • ACLR patients show medially directed COP in FFPOP subphase in running and walking. • ACLR patients exhibit greater foot progression angle in walking and running. • Injured leg showed shorter contact time while running. • Running is more sensitive in showing roll-off characteristics in ACLR patients. [ABSTRACT FROM AUTHOR]

The phenomenon of droplet impact on moving surfaces is widely observed in fields such as transportation, rotating machinery, and inkjet printing. Droplets exhibit non-axisymmetric behavior due to the motion of solid surfaces which significantly determines core parameters such as contact time, maximum spreading radius, and bounding velocity, thereby affecting the efficiency of related applications. In this study, we focus on the kinetics and morphology of the non-axisymmetric bouncing behaviors for droplets impacting on a moving superhydrophobic surface (SHPS) within the normal (Wen) and tangential (Wet) Weber numbers. Considering the influences of the moving surface on the contact area and contact time, the previous scaling formula for the horizontal velocity of droplets has been improved. Based on the velocity superposition hypothesis, we establish a theoretical model for the ratio of the maximum spreading radius at both ends depending on Wen and Wet. This research provides both experimental and theoretical evidence for understanding and controlling the non-axisymmetric behavior of droplets impacting on moving surfaces. [ABSTRACT FROM AUTHOR]

We aimed to investigate the initial foot contact and contact time in experienced endurance runners at individualized speeds, in running shoes and barefoot. Forty-eight participants (33.71±7.49 y, 70.94±8.65 kg, 175.07±7.03 cm, maximum aerobic speed 18.41±1.54 km. h-1) were distributed into three groups according to athletic performance: highly-trained runners, middle-trained runners, and control group. An incremental running test until exhaustion was performed for assessing maximum aerobic speed. After≥24 h of recovery participants randomly walked and ran, barefoot and in running shoes, over a pressure plate at ~4.7 km. h-1 and 85% of the maximum aerobic speed, respectively. They wore the same model of running shoes with homogeneous lacing pattern. A rearfoot strike was performed by 68.8% and 77.1% of participants when running barefoot and in running shoes, respectively. Considering the tendency to develop a rearfoot strike was lower in the barefoot condition, runners with higher performance may benefit from training in minimalist running shoes because their foot contact pattern could tend towards a non-rearfoot strike. Our results suggest that initial foot contact and contact time are related to running performance and may also be influenced by running shoes. [ABSTRACT FROM AUTHOR]

Rotational moulding is a versatile polymer shaping process used to create enclosed parts from powdered precursors using heat and multi-axis rotation. Controlling the heating process and mould motion is critical to producing high-quality parts, and failures due to incorrect mould coverage or variable wall thickness are common. To date, limited simulation tools exist to predict the motion of the powder within the mould, and operators rely on unreliable prior experience to avoid defects. This paper presents an SPH simulation framework to predict particle flow patterns and powder contact time within a rotating mould. The powder-to-wall contact time was derived from the transient rigid body force (RBF) of different sensors on the mould. The method was compared with the results of DEM simulation and validated by the particle flow pattern of two experimental results. Results showed that the SPH method was capable of simulating particle flow macroscopic properties. The great computing efficiency of SPH compared to DEM simulation was also demonstrated. • Couple the SPH framework with a soil material model to simulate the polymer flow motion during rotational moulding process. • Modelling framework validated by two experimental benchmarks. • Present a significant benefit compared to the DEM method when simulating particle flow with millions of particles. [ABSTRACT FROM AUTHOR]

The use of an ozonized bubble column reactor (OBCR) in wastewater treatment is advantageous due to its efficient mixing and mass transfer characteristics. Among all high-performance features, the ozonation reaction in a BCR undergoes a low dissolution of O3 in the reactor with a limited reaction rate. In this study, the ozonation reaction of phenol in an OBCR was tested using a ZnO nanocatalyst and alumina balls as packing material. Three concentrations of O3 were evaluated (i.e., 10, 15, and 20 ppm), and 20 ppm was found to be the optimum concentration for phenol degradation. Also, two doses (i.e., 0.05 and 0.1 g/L) of ZnO nanocatalysts were applied in the reaction mixture, with the optimal dose found to be 0.1 g/L. Accordingly, three phenol concentrations were investigated in the OBCR (i.e., 15, 20, and 25 ppm) using four treatment methods (i.e., O3 alone, O3/Al2O3, O3/ZnO nanocatalyst, and O3/Al2O3/ZnO nanocatalyst). At a contact time of 60 min and phenol concentration of 15 ppm, the removal rate was 66.2, 73.1, 74.5, and 86.8% for each treatment method, respectively. The treatment experiment that applied the O3/Al2O3/ZnO nanocatalyst produced the highest phenol conversion into CO2 and H2O in the shortest contact time for all phenol concentrations. Thus, the OBCR employed with a ZnO nanocatalyst plus packing material is a promising technology for the rapid and active removal of phenol because it enhances the number of hydroxyl radicals (•OH) generated, which ultimately increases the oxidation activity in the OBCR. Also, the results showed efficient flow characteristics in the OBCR, with channeling problems averted due to appropriate gas movement resulting from the use of packing materials. Finally, it was found that the ozonation process in an OBCR is an efficient method for phenol conversion with good economic feasibility. [ABSTRACT FROM AUTHOR]

Copyright of Revija Šport is the property of Sport: Revija Za Teoreticna in Praticna Vprasanja Sporta and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The purpose of this study was to investigate the correlation between the reactive strength index (RSI) using the drop jump (DJ) and the isometric rate of torque development (RTD) with weightlifting performance in national-level weightlifters. Seven male weightlifters (age: 28.3 ± 5.7 years, body mass: 80.5 ± 6.7 kg, body height: 1.73 ± 0.07 m) participated in this study. Measurements were performed 2 weeks prior to the national championship and included the countermovement jump (CMJ), the squat jump (SJ), the DJ from three different drop heights (20, 30, and 40 cm), and the isometric peak torque (IPT) and RTD. Performance in CMJ and SJ was significantly correlated with weightlifting performance (r ranging from 0.756 to 0.892). Significant correlations were found between weightlifting performance with DJ contact time (r ranging from −0.759 to −0.899) and RSI (r ranging from 0.790 to 0.922). Moreover, the best RSI was significantly correlated with the snatch (r = 0.921, p = 0.003) and total performance (r = 0.832, p = 0.020). Small to very large correlations were found between IPT and RTD with weightlifting performance (r ranging from 0.254 to 0.796). These results suggest that RSI and contact time variables from DJ may predict weightlifting performance in well-trained weightlifters. Additionally, IPT and RTD may provide useful insights into the neuromuscular fitness condition of the weightlifter. [ABSTRACT FROM AUTHOR]

Mining waste such as copper slag contains different types of potentially toxic metal elements. Transportation, crushing and subsequent storage of copper slag in undesignated areas can increase the potential of these elements being released to the environment, resulting in negative environmental impacts. This study investigated the leaching behavior of copper and cobalt from Nkana smelter copper slag dump under different conditions. The effect of particle size, pH of the leaching agent, and contact time on the release of copper and cobalt was investigated. The slag samples were granulated into six different grain sizes and subjected to different pH levels treated for 33 days. To assess the hazardous nature of a material within the natural environment, batch leaching techniques, as outlined in EN 12457–2:2002, were employed.The results showed that the pH 2.0 of the leaching agent had a more significant effect on the release of both copper and cobalt than residence time and particle size. The optimal particle sizes for copper and cobalt release were 0.075–0.150 and 0.150–0.250 mm, respectively. The optimal leaching time was 33 days for both metals. In order to prevent the mobility of copper and cobalt from Nkana slag dump into the aquatic environment, acidic pH levels and smaller particles

Abstract Background Disinfectant towelettes are increasingly being used as a means to prevent transmission of clinically important pathogens which could lead to healthcare-associated infections (HAIs). However, the efficacy of disinfectant towelette products when tested under realistic use conditions is understudied. A test model was designed to replicate realistic wiping conditions. The objective of this study was to determine the impact of varied contact time on disinfectant towelette efficacy under these conditions. Methods Five product types were tested against Staphylococcus aureus (ATCC 6538) and Pseudomonas aeruginosa (ATCC 15,442) at five contact times (30 s, one min, two min, three min, and 10 min) on hard, non-porous laminate templates to determine the impact of contact time on disinfectant towelette efficacy when tested under realistic use. Results Product type had a significant impact on the efficacy of disinfectant towelettes when tested under conditions reflective of realistic use. The effect of contact time was limited and no differences in efficacy were seen at a contact time of one min compared with the other contact times tested. Only one disinfectant towelette product achieved a mean 5-log reduction under the tested conditions. Conclusion Efficacy of disinfectant towelettes was primarily impacted by product type when applied in a model designed to replicate realistic use in which only a limited effect of contact time was observed. There is a need for further investigation into which factors have the greatest impact on disinfectant towelette efficacy when applied in clinical settings.

A study on the removal of hexavalent chromium by adsorption of rice husk nanosilica was attempted. The usage of chromium causes immense pollution as it is used in the leather industry, metal finishing, electroplating, and chromate preparations. To understand the adsorption capacity and its behavior, as well as the adsorption potential of rice husk nanosilica, the effluent used in this experiment is tannery wastewater. The experiment was conducted in tannery industrial wastewater using nanosilica extracted from rice husks ash for various pH, contact time, and adsorbent dosages. The result shows 88.3% chromium removal using rice husk ash nanosilica (RHANS) at pH 4, 1.75 mg adsorbent dosage, and 50 min of contact time. Removal of chromium by this method was a more economical and alternative process. RHANS was selected due to its source availability and antimicrobial properties. [ABSTRACT FROM AUTHOR]

Background: Cyanazine (CYZ) is one of the triazine herbicides to prevent broadleaf grass and weeds in crops. Despite its affordability and productivity in increasing crop yield, the extensive usage of CYZ contributes to environmental pollution and poses risks to living organisms. Most research has focused on detecting CYZ in the environment and its toxicity to humans and the ecosystem. For these reasons, molecular imprinting technology (MIT) can be applied to produce an effective adsorbent material of high binding affinity and selectivity towards its target compound which is known as molecularly imprinted polymers (MIPs). In this study, MIP was prepared by precipitation polymerization using CYZ as a template molecule, methacrylic acid (MAA), acrylamide (AAm) and 4-vinylpyridine (4VP) as functional monomers, and ethylene glycol dimethacrylate (EGDMA) as cross-linker in the ratio of 1:6:12, respectively. The effects of contact time, initial concentration, pH, and polymer dosages on the adsorption efficiencies of MIPs were also investigated in this study. Results: MIPs of CYZ were successfully synthesized by precipitation polymerization method with a non-covalent approach using different functional monomers such as methacrylic acid (MAA), acrylamide (AAm) and 4-vinylpyridine (4VP). For the comparison study, the non-imprinted polymer (NIP) was synthesized without the addition of CYZ, the template molecule. The FTIR analysis indicated the interactions among CYZ and functional monomers (MAA, AAm or 4VP) in the presence of EGDMA as a cross-linker. The FESEM analysis showed that only MIP (AAm) and NIP (AAm) had regular and spherical polymer particles while MIP (MAA), NIP (MAA), MIP (4VP) and NIP (4VP) were agglomerated and irregular in shape. The EDX analysis showed that the MIPs were mainly composed of carbon and oxygen. Meanwhile, the BET analysis of MIP (AAm) had higher surface area, total pore volume and average pore radius than that NIP (AAm). Based on the batch binding study, MIP (AAm) (83.30%) had the highest binding efficiency than the MIP (MAA) (76.96%) and MIP (2VP) (76.90%) at a contact time of 240 min. The optimum conditions for the highest binding efficiency of MIP (AAm) were obtained at an initial concentration of 6 ppm, pH 7 and polymer dosage of 0.1 g polymer beads. The adsorption efficiency of MIP (AAm) with CYZ at the optimum parameters resulted in 86.39%. The selectivity test showed that MIP (AAm) was more selective towards CYZ than AME, the competitive compound with relative selectivity coefficient of 2.36. The kinetic isotherm of MIP (AAm) was best explained according to the pseudo-second-order kinetic model while the adsorption isotherm of MIP (AAm) was based on the Langmuir adsorption isotherm model. The MIP (AAm) was tested in the distilled water (DIW), tap water and river water spiked with CYZ and a substantial amount of CYZ was removed with a recovery of 86.67%, 84.75% and 84.69%, respectively. Conclusion: The MIPs of CYZ were successfully synthesized by the precipitation polymerization method using different functional monomers. Among those MIPs, MIP (AAm) showed the highest rebinding efficiency and therefore this MIP was selected for further studies. The best combination of CYZ, AAm was the main factor that contributed to the morphological and chemical properties, as well as the efficiency and selective binding performance of MIP (AAm). Since MIP (AAm) showed a substantial removal efficiency of CYZ in the environment specifically water sources, it has the capability to act as an adsorbent material for various purposes such as solid-phase extraction techniques and a stationary phase in various chromatographic techniques. [ABSTRACT FROM AUTHOR]

In this study, the effect of the use of environmentally friendly materials (sawdust) in the reduction of some heavy elements of industrial wastewater was studied. The removal of lead and copper elements was tested. In order to evaluate the effect of this material and other factors in increasing the efficiency of removal, different concentrations of heavy elements of lead and copper 5, 10, 15, and 20 mg/l and contact time (10, 20, 30, and 40 s) were tested. The effect of pH was also investigated at levels of (3, 5, 7, and 10, as well as the impact of the amount of sawdust used and the rate of speed of mixing was 75, 100, 150, and 250 rpm. The results showed that the highest lead removal efficiency was (95%) when using 2 gm of sawdust at ten pH. In comparison, the highest removal efficiency of copper was 92.5%, when the pH 7 and the study of the number of revolutions and contact time. The results were good indicators when the value of the agitation speed was 75 rpm. Lead removal was 98%, and copper was 94.5% at a speed of 100 rpm. The result also recorded significant effect of time on the removal efficiency; the efficiency of removal of copper was 90-94% at 30 min, while the removal efficiency of lead was 70-73% at 34-40 minute period. [ABSTRACT FROM AUTHOR]

Purpose: To examine the effect of a 10-week plyometric training (PT) on the kinematic and kinetic properties of prepubescent girls during squat jump, countermovement jump, and drop jumps. Methods: Twenty-four untrained girls (aged 9–11 y) were assigned to a training group (TG) and a control group. The TG followed twice a week PT for 10 weeks. Squat jump, countermovement jump, and drop jumps performed from heights of 20, 35, and 50 cm were tested before and after PT. Jump height, kinematic, and kinetic parameters were evaluated using a motion analysis system and a force plate. Results: Jumping height in all jump types increased significantly after PT for the TG (P <.001). After training, the TG presented increased power (P <.001) and knee angular velocity (P <.001), higher knee flexion at the deepest point during the braking phase (P <.001), longer contact time (P <.001), and unchanged stiffness and reaction strength index (P >.05). No differences were observed in the control group (P >.05). Conclusion: These findings indicate that a 10-week PT positively affected jumping performance in prepubescent girls who improved their drop jump performance after training not by adopting a stiff/bouncing jumping style of short contact time and increased stiffness, but a compliant/absorbing style of prolonged contact time. [ABSTRACT FROM AUTHOR]

Background: Disinfectant towelettes are increasingly being used as a means to prevent transmission of clinically important pathogens which could lead to healthcare-associated infections (HAIs). However, the efficacy of disinfectant towelette products when tested under realistic use conditions is understudied. A test model was designed to replicate realistic wiping conditions. The objective of this study was to determine the impact of varied contact time on disinfectant towelette efficacy under these conditions. Methods: Five product types were tested against Staphylococcus aureus (ATCC 6538) and Pseudomonas aeruginosa (ATCC 15,442) at five contact times (30 s, one min, two min, three min, and 10 min) on hard, non-porous laminate templates to determine the impact of contact time on disinfectant towelette efficacy when tested under realistic use. Results: Product type had a significant impact on the efficacy of disinfectant towelettes when tested under conditions reflective of realistic use. The effect of contact time was limited and no differences in efficacy were seen at a contact time of one min compared with the other contact times tested. Only one disinfectant towelette product achieved a mean 5-log reduction under the tested conditions. Conclusion: Efficacy of disinfectant towelettes was primarily impacted by product type when applied in a model designed to replicate realistic use in which only a limited effect of contact time was observed. There is a need for further investigation into which factors have the greatest impact on disinfectant towelette efficacy when applied in clinical settings. Highlights: Contact time had limited impact on the efficacy of disinfectant towelettes. Product type significantly impacted the efficacy of disinfectant towelettes. Disinfectant towelettes did not achieve expected log reductions under conditions of realistic use. [ABSTRACT FROM AUTHOR]

Aqueous solution containing different concentrations of methylene blue dye was treated with chemically modified aluminium foil/PVA blends. There have been impressive decolourisation of the dye molecules in the aqueous system treated with the blends. Contact time and amount of composite facilitate more decolourisation of the dye solution. 97 % dye removal has been recorded at optimum conditions of the experiment. Energy dispersive X-ray fluorescence (EDXRF) analysis was used to determine the elemental composition of the aluminium foil and FTIR analysis was used to ascertain the composite formation between the foil and PVA. The blends have shown an impressive swelling property in aqueous system and poor to moderate in other organic solvents. [ABSTRACT FROM AUTHOR]

The overuse and misuse of antibiotics can pose the risk of spreading mutant strains that show antimicrobial resistance (AMR), with negative impacts on the management of bacterial infections and economic implications for healthcare systems. The research and development of natural antibacterial agents could be a priority in the next years to improve a number of effective antibacterial molecules and to reduce the AMR phenomenon and its development. The present study identified the most effective concentration and contact time of Thymus vulgaris L. essential oil (TEO) to obtain bactericidal effects in vitro against different Gram-positive and Gram-negative bacterial strains. Six clinically isolated (wild types) bacterial strains, (Citrobacter freundii, Enterococcus feciorum, Proteus mirabilis, Acinetobacter cioffi, Pseudomonas putrefaciens and Klebsiella pneumoniae) and two ATCCs (Staphylococcus aureus and Streptococcus mutans) were tested after 1 min, 3 min and 5 min of contact with TEO. The preliminary results on S. aureus after 24 h of incubation revealed a TEO concentration of 9.28 mg/mL (w/v) that completely inhibited bacteria growth, keeping cell viability. The total suppression of bacterial growth at all tested contact times was observed for all tested bacterial strains, and the results were confirmed after 48 h of incubation. Bacterial growth suppression was confirmed even with the presence of organic components. These preliminary results showed the in vitro antimicrobial efficacy of TEO against different Gram-positive and Gram-negative bacterial strains. Future studies are necessary to confirm the reproducibility of these results even on other strains and to define the exact molecular mechanisms of EOs in order to consider TEO as a valid alternative to classic antibiotic therapies and subsequently to reduce the occurrence of AMR. [ABSTRACT FROM AUTHOR]

Background: The aim was to analyze changes in normal functional parameters of gait analysis by aging, sex, and body mass index (BMI). Methods: A cross-sectional study with a consecutive sample of asymptomatic subjects was performed between 2014 and 2020. Primary outcomes were time and force parameters (contact time and center of force [CoF] time), in the heel, midfoot, and metatarsal areas, measured using an in-office force platform. Results: A total of 156 subjects (312 feet) were included, including 67% of women with a mean age of 47 years. The mean of total contact time was similar in males and females (P = .695) and across BMI (P = .413). Contact time did not show differences by region (P = .648 heel, P = .286 midfoot, and P = .690 metatarsal). CoF time in the heel and metatarsal areas did not change between males and females (P = .288 and P = .879, respectively); meanwhile, it was different in midfoot (P = .002). Maximum force showed a reduction between sexes in the heel (P = .039) but did not in the midfoot and metatarsal areas. By age, differences were detected in the heel and metatarsal areas in females (P = .002 and P = .001) and the metatarsal area in males (P = .001). According to the age groups, total contact time increased in females (P = .001) but not in males (P = .018), and no differences were detected between foot areas. In females, CoF time did not change either foot areas or age groups. In males, CoF time values increased in the midfoot area in the older group (P = .001). Conclusion: Time variables did not change by foot region, independent of age, sex, and BMI. Heel maximum force decreased in females, probably linked to adaptive phenomena by aging. The midfoot remains stable, and acts as an undamaged "bridge." These parameters could be interpreted as normal in asymptomatic subjects. [ABSTRACT FROM AUTHOR]

Humic acid is one of the green materials for wastewater treatment including for removal dyes as an adsorbent. Humic acid was isolated from peat soil, Gambut Regency, South Kalimantan following International Humic Substances Society method, and used to adsorb Congo red. The adsorption process was carried out in a batch system and the effect of pH, contact time, and adsorption capacity of Congo red on humic acid were studied. The adsorbent characterization by using FTIR. The results showed that the adsorption of Congo red on humic acid occurred at the optimum pH of pH 6, the optimum contact time was 120 minutes. The adsorption capacity of Congo red onto humic acid of 33.33 mg/g and follows the Langmuir model with R² = 0.9926. The characterization of humic acid functional groups before and after adsorption of Congo red showed that the signal at 1,712.79 cm-1 were shifted to 1,705.07 cm-1 and 1,273.02 cm-1 were shifted to 1,265.30 cm-1. These suggested that the mechanism interaction was the electrostatic interaction between -NH3+ functional group of Congo red group and -COO- functional group of humic acid. It means that humic acid isolated from peat soil could be used as an adsorbent for the removal Congo red. [ABSTRACT FROM AUTHOR]

Abstract The runoff of textile dye effluents into public water bodies is a major environmental and health problem. Color removal, in particular, has recently become of substantial scientific interest, as revealed by the multitude of related research reports. The present study focused on measuring the efficiency of two marine algae, Ulva fasciata and Pterocladia capillacea, in bio-removal of four synthetic dyes (RY2, RR195, RB19, and RB5) based on the fresh and dried biomass of the tested algal species. According to the highest removal efficiencies of the dyes, two algal species were chosen from among nine different algae. Bio-removal efficiency was examined under the effects of salinity and contact time. The results of this experiment revealed that algae achieved high bio-removal efficiency of the examined dyes in both fresh and saline water, but the removal percentages were higher in saline water compared to fresh conditions. The highest removal percentage recorded after 8 h by fresh U. fasciata in saline water reached 82.75 and 83.23% for RY2 and RR195 dyes, respectively. Contact time has the highest impact on dye removal in both algal species. The highest removal values were obtained in the case of dried U. fasciata, which achieved impressive removal percentages that reached 100% for RB195 and RB5 and fresh P. capillacea which had high removal percentages of 91.11, 94.85 and 97.13% for RR195, RB19, and RB5 dyes, respectively, after 8 h. Our results revealed that the used algal species were highly significant in the biosorption of most used dyes.

The purpose of this study was to determine if running biomechanical variables measured by wearable technology were prospectively associated with running injuries in Active Duty Soldiers. A total of 171 Soldiers wore a shoe pod that collected data on running foot strike pattern, step rate, step length and contact time for 6 weeks. Running-related injuries were determined by medical record review 12 months post-study enrollment. Differences in running biomechanics between injured and non-injured runners were compared using independent t-tests or ANCOVA for continuous variables and chi-square analyses for the association of categorical variables. Kaplan–Meier survival curves were used to estimate the time to a running-related injury. Risk factors were carried forward to estimate hazard ratios using Cox proportional hazard regression models. Forty-one participants (24%) sustained a running-related injury. Injured participants had a lower step rate than non-injured participants, but step rate did not have a significant effect on time to injury. Participants with the longest contact time were at a 2.25 times greater risk for a running-related injury; they were also relatively slower, heavier, and older. Concomitant with known demographic risk factors for injury, contact time may be an additional indicator of a running-related injury risk in Active Duty Soldiers. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate individual variations in running kinematics at various running intensities by considering the potential differences in runners' abilities. It is essential to recognize that running kinematic dynamics may not remain identical at different intensities, even among runners with similar performance abilities. To avoid assumptions based solely on group data, this study focused on individual variations as a key objective. The research involved three male runners who demonstrated similar 3000 m running times, ranging from 9:02 to 9:08 min. These participants underwent a series of running tests on a leveled treadmill, during which comprehensive measurements of running kinematics, heart rate, and blood lactate values were recorded. The running velocity was in the range of 12-20 km/h, and nine individual tests were conducted with a randomized order of velocities. Analysis of the heart rate data revealed variations in exercise response both within and between individuals. However, among these three runners, general physiological responses, including the heart rate and lactate concentration, were similar. This study shows that running velocity significantly affects various kinematic characteristics of running such as the step length, step frequency, contact time, and flight time. The findings indicate that with an increase in the running velocity, there is a corresponding increase in the step length and stride frequency, a decrease in the contact time, and an increase in the flight time. Furthermore, a strong positive correlation between the step length and running velocity is observed; there is also a general trend of stride frequency increasing with higher running velocity, although this result is not always statistically significant. In conclusion, this study highlights the importance of considering individual variations in running kinematics when assessing the effects of different running intensities. [ABSTRACT FROM AUTHOR]

Superhydrophobic surfaces could repel water due to the capillary force associated with surface roughness, which has a large range of applications, such as underwater drag reduction, heat transfer enhancement, oil/water separation, and so on. However, the engineering applications of superhydrophobic surfaces rely on the stability of the superhydrophobic surfaces. In this study, a hydrophilic metal mesh was modified to be superhydrophobic. The resulting superhydrophobic mesh was designed as a bowl capable of holding water without leaking and as a boat floating on top of water without sinking. The stability of an impacting droplet on a superhydrophobic mesh was investigated using both experiments and theoretical analysis. It was demonstrated that the capillary force is able to prevent water from passing through the mesh and maintain the stability of the air–water interface under dynamic pressure. Furthermore, a theoretical model was developed to diagnose the stability of the air–water interface on the superhydrophobic mesh when in contact with water, and the results are consistent with the experimental findings. The results of this work can be utilized to design robust superhydrophobic meshes and advance the field of droplet manipulation. [ABSTRACT FROM AUTHOR]

The runoff of textile dye effluents into public water bodies is a major environmental and health problem. Color removal, in particular, has recently become of substantial scientific interest, as revealed by the multitude of related research reports. The present study focused on measuring the efficiency of two marine algae, Ulva fasciata and Pterocladia capillacea, in bio-removal of four synthetic dyes (RY2, RR195, RB19, and RB5) based on the fresh and dried biomass of the tested algal species. According to the highest removal efficiencies of the dyes, two algal species were chosen from among nine different algae. Bio-removal efficiency was examined under the effects of salinity and contact time. The results of this experiment revealed that algae achieved high bio-removal efficiency of the examined dyes in both fresh and saline water, but the removal percentages were higher in saline water compared to fresh conditions. The highest removal percentage recorded after 8 h by fresh U. fasciata in saline water reached 82.75 and 83.23% for RY2 and RR195 dyes, respectively. Contact time has the highest impact on dye removal in both algal species. The highest removal values were obtained in the case of dried U. fasciata, which achieved impressive removal percentages that reached 100% for RB195 and RB5 and fresh P. capillacea which had high removal percentages of 91.11, 94.85 and 97.13% for RR195, RB19, and RB5 dyes, respectively, after 8 h. Our results revealed that the used algal species were highly significant in the biosorption of most used dyes. [ABSTRACT FROM AUTHOR]

The phenomenon of droplet impact on moving surfaces is widely observed in fields such as transportation, rotating machinery, and inkjet printing. Droplets exhibit non-axisymmetric behavior due to the motion of solid surfaces which significantly determines core parameters such as contact time, maximum spreading radius, and bounding velocity, thereby affecting the efficiency of related applications. In this study, we focus on the kinetics and morphology of the non-axisymmetric bouncing behaviors for droplets impacting on a moving superhydrophobic surface (SHPS) within the normal (Wen) and tangential (Wet) Weber numbers. Considering the influences of the moving surface on the contact area and contact time, the previous scaling formula for the horizontal velocity of droplets has been improved. Based on the velocity superposition hypothesis, we establish a theoretical model for the ratio of the maximum spreading radius at both ends depending on Wen and Wet. This research provides both experimental and theoretical evidence for understanding and controlling the non-axisymmetric behavior of droplets impacting on moving surfaces.

Purpose: To examine the net oxygen cost, oxygen kinetics, and kinematics of level and uphill running in elite ultralrail runners. Methods: Twelve top-level ultradistance trail runners performed two 5-min stages of treadmill running (level, 0%, men 15 km⋅-1, women 13 km⋅-1; uphill, 12%, men 10 km⋅h-1, women 9 km&#8901-1). Gas exchanges were measured to obtain the net oxygen cost and assess oxygen kinetics. In addition, running kinematics were recorded with inertial measurement unit motion sensors on the wrist, head, belt, and foot. Results: Relationships resulted between level and uphill running regarding oxygen uptake (...O2), respiratory exchange ratio, net energy, and oxygen cost, as well as oxygen kinetics parameters of amplitude and time delay of the primary phase and time to reach ...O2 steady state. Of interest, net oxygen cost demonstrated a significant correlation between level and uphill conditions (r= .826, P < .01). Kinematics parameters demonstrated relationships between level and uphill running, as well (including contact time, aerial time, stride frequency, and stiffness; all P < .01). Conclusion: This study indicated strong relationships between level and uphill values of net oxygen cost, the time constant of the primary phase of oxygen kinetics, and biomechanical parameters of contact and aerial time, stride frequency, and stiffness in elite mountain ultratrail runners. The results show that these top-level athletes are specially trained for uphill locomotion at the expense of their level running performance and suggest that uphill running is of utmost importance for success in mountain ultratrail races. [ABSTRACT FROM AUTHOR]

The antibacterial action of the carob tree offers the possibility of using it for the disinfection of treated wastewater in biological process wastewater treatment plants. This paper reviews studies conducted to investigate the effect of carob tree on the reduction of indicator bacteria of fecal contamination that cannot be removed after the secondary stage of biological treatment. The aim is to use the wastewater safely in irrigation and expand the list of irrigable plants with this unexploited resource. Physico-chemical and bacteriological parameters were used to determine the optimal conditions and evaluate the treatment’s efficiency. A contact time of 1 h and a dose of 1 mL of disinfectant reduced E. coli and fecal coliforms from 5.105 CFU to 1 237 CFU (99.75%) and from 7.106 CFU to 1 505 CFU (99.98%), respectively. For the same contact time, the fecal streptococci were reduced from 4.105 CFU to 59 CFU (99.99%). According to WHO standards, this dose and contact time are sufficient to use this water for irrigation. A minimum contact time of 2 h with a dose of 1 mL of the aqueous extract of the green pod of the carob is required to obtain a reduction of E. coli and fecal coliforms from 5.105 CFU to 5 254 CFU (99.95%) and from 7.106 CFU to 340 CFU (99. 99%) to meet the Algerian standards of reuse of treated wastewater being more stringent. The results show that the same conditions reduce fecal streptococci from 4.105 CFU to 5 CFU (99.99%). This elimination level shows that green carob juice can be used for disinfection with the necessary doses for each bacterial load and sufficient contact time.

Machine learning (ML) was used to predict contact ( t c ) and flight ( t f ) time, duty factor (DF) and peak vertical force ( F v , m a x ) from IMU-based estimations. One hundred runners ran on an instrumented treadmill (9–13 km/h) while wearing a sacral-mounted IMU. Linear regression (LR), support vector regression and two-layer neural-network were trained (80 participants) using IMU-based estimations, running speed, stride frequency and body mass. Predictions (remaining 20 participants) were compared to gold standard (kinetic data collected using the force plate) by calculating the mean absolute percentage error (MAPE). MAPEs of F v , m a x did not significantly differ among its estimation and predictions (P = 0.37), while prediction MAPEs for t c , t f and DF were significantly smaller than corresponding estimation MAPEs (P ≤ 0.003). There were no significant differences among prediction MAPEs obtained from the three ML models (P ≥ 0.80). Errors of the ML models were equal to or smaller than (≤32%) the smallest real difference for the four variables, while errors of the estimations were not (15–45%), indicating that ML models were sufficiently accurate to detect a clinically important difference. The simplest ML model (LR) should be used to improve the accuracy of the IMU-based estimations. These improvements may be beneficial when monitoring running-related injury risk factors in real-world settings. [ABSTRACT FROM AUTHOR]

[Display omitted] The unbalanced capillary force provided by wettability patterns, non-uniform/asymmetric microtextures enables directional droplet transport, while macrotextures have shown potentials in reducing the contact time. Inspired by these findings, we design millimeter superhydrophobic stepped surfaces to simultaneously achieve highly steerable directional bouncing and contact time reduction of impacting droplets. The stepped surfaces are fabricated by computerized numerical control, chemical oxidation, hydrophobic treatment. Systematic impact experiments are conducted under Weber number ranging from 10.5 to 20.5, two step heights (0.5 mm and 1.0 mm) and extensive impact positions. Compared with known microtextured surfaces, the stepped surfaces exhibit excellent performance with the maximum lateral movement distance about 8 times of droplet radius, controllable rebound angle ranging from ∼ 32° to ∼ 90° and up to ∼ 30 % reduction in contact time. Particularly, we divide the directional bouncing characteristics into six regimes and attribute the variation of rebound velocity by the synergistic effects of viscous dissipation, excess surface energy, excess kinetic energy. It is demonstrated that the contact time is reduced by liquid mass redistribution and asymmetry enhancement. Predictive models of contact time that incorporate the coupling effects of impact position, impact velocity and step height are also established. [ABSTRACT FROM AUTHOR]

• The multiple droplets impact is compared under symmetrical and asymmetrical impact condition. • Distinct rebound modes are found under symmetrical and asymmetrical impact condition. • The contact time of multiple droplets impact is analyzed under various rebound modes. • The effect of angular momentums on the contact time is revealed for multiple droplets impacts. The rebound dynamics of multiple impinging droplets is investigated and compared under the symmetrical and asymmetrical impact conditions. The result shows that at various relative velocities, when multiple droplets symmetrically impinge macrotextured superhydrophobic surfaces, the rebound modes consist of the left–right non-simultaneous rebound (LRNSR), the coalescence-split simultaneous rebound (CSSR) and the right-left non-simultaneous rebound (RLNSR). With the transition of rebound modes, the contact time is first reduced under the LRNSR mode and then constant under the CSSR and RLNSR modes as the relative velocity is increased. Whereas when multiple droplets asymmetrically impinge macrotextured superhydrophobic surfaces, the rebound modes consist of the left-ridge-right rebound (LRIRR), the left–right-ridge rebound (LRRIR) and LRNSR. When the relative velocity is increased, the contact time is first reduced under the LRIRR mode and then constant under the LRRIR mode. But under the LRNSR mode, the first reduced and then constant contact time appears with increased relative-velocities. [ABSTRACT FROM AUTHOR]