Longer Contact Time Research Articles

Mechanisms and application of the IAST-EBC model for predicting 2-MIB adsorption by PAC in authentic raw waters: Correlation between NOM competitiveness and water quality parameters

Natural organic matter (NOM) exerts negative impacts on 2-methylisoborneol (2-MIB) removal by powdered activated carbon (PAC), thus adding to the difficulty in accurate PAC dose prediction. Our study investigated the application of the ideal adsorbed solution theory-equivalent background compound (IAST-EBC) model and its simplified version for PAC dose prediction. Four raw water samples were employed, and the corresponding C0,EBC values, indicating NOM competitiveness, were calculated. The results showed that the IAST-EBC model presented ideal predictive performance in 2-MIB adsorption under both equilibrium and nonequilibrium conditions and the C0,EBC values of the Huangpu River (8800 ng/L) and Qiantang River (10300 ng/L) were high, representing the higher NOM competitiveness in these two rivers, which may be caused by municipal effluent and industrial wastewater discharge. In contrast, Tai Lake water showed a lower C0,EBC value (6400 ng/L), which was likely associated with algae and other microbial activities. The fluorescence index (FI, the ratio of Ex/Em = 370/470 nm to Ex/Em = 370/520 nm) can be applied to estimate C0,EBC, thus facilitating prediction. Our study also showed that the IAST-EBC model can be further simplified under lower initial 2-MIB concentrations or longer contact times, which is particularly useful for practical applications.

Optimization of Ultrasound-Assisted Extraction of Spent Coffee Grounds Oil Using Response Surface Methodology

Spent coffee grounds (SCGs) generated in coffee processing for beverages and other products are a very significant organic residue that needs to be properly treated. Waste valorization via oil extraction has the potential to obtain compounds that can be used for producing biodiesel or other high-value products, such as polymers. This work focuses on the ultrasound-assisted extraction of SCG oil using n-hexane as a solvent. Three key process parameters are analyzed: temperature, extraction time, and liquid/solid (L/S) rate of solvent, using a central composite rotatable design (CCRD), an analysis that, to the author’s knowledge, is not yet available in the literature. The data were analyzed using the software StatSoft STATISTICA 13.1 (TIBCO Software Inc., Palo Alto, CA, USA). Results show that all parameters have a statistical influence on the process performance (p < 0.05), being the L/S ratio the most significant, followed by extraction time and temperature. An analysis of variance (ANOVA) showed that the empirical model is a good fit to the experimental data at a 95% confidence level. For the range of conditions considered in this work, the optimal operating conditions for obtaining an oil extraction yield in the range of 12 to 13%wt are a solvent L/S ratio of around 16 mL g−1, for a temperature in the range of 50 to 60 °C, and the longest contact time, limited by the process economics and health and safety issues and also, by the n-hexane boiling temperature.

Lipid oxidation during the beating of cake batter containing yellow pea (Pisum sativum L.) flour

The aim of this study was to understand the impact of ingredients and processes on reactivity during sponge cake batter making using yellow pea flour. Numerous volatiles were identified, mainly originating from the degradation of linoleic and linolenic acid catalyzed by 10- and 13-lipoxygenases. The extent of lipid oxidation depended on the beating process, owing to the effect on local ingredient distribution and the exposure time of lipoxygenase to its substrates. Although prolonged beating after the addition of either flour or oil did not favor volatile formation, the latter led to elevated quantities of hydroperoxides. This intensified oxidation was assigned to an improved homogeneity and reduced size of lipid droplets and air cells. A sequential increase in both mixing times significantly increased the amount of volatiles, which could be attributed to a larger reaction interface and longer contact time between reactive ingredients. These results highlight the importance of parameter controls to limiting the generation of volatiles with odor activity.

Leveraging slow DOTA f-element complexation kinetics to enable separations by kinetic design

The design of metal-concerned solvent extraction systems frequently leverages thermodynamically derived differences in selectivity. An alternative approach, leveraging kinetic control, has been considered much less seriously. Our recent manuscript describing DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) complexation kinetics across the lanthanide series shows the observed rate constant steadily increases across the series, with some non-monotonic behavior observed at terbium and thulium. This contrasts the thermodynamic stability constant trend, where lanthanide-DOTA stability constants initially increase and then plateau as a function of ionic radii after samarium. To leverage the kinetic differences of DOTA with the lanthanides across the series, kinetically based separations must be utilized. Since DOTA has very slow complexation kinetics, a separations system must expedite DOTA-metal complexation to allow a separation approximating practical application. In this report, a DOTA-based solvent extraction system, where DOTA is the aqueous holdback reagent and bis-2,4,4-trimethylpentylphosphinic acid (Cyanex 272) is the organic phase extractant, is demonstrated and compares the separations chemistry of Nd, Eu and Am. The slowness of DOTA complexation was addressed by heating the system. Results showed, in general, separation between metals is better during early phase contact, and diminishes under longer contact times. Under all conditions, separations are better than would be predicted based on a thermodynamic basis. This report suggests that while slowly complexing ligands classically used for biological applications may not be appropriate for thermodynamically designed metal separations, their use for kinetically based systems may be appropriate and enable a new design basis for f-element separations.

Formation of Interface Layers between Corundum‐Based Refractory Ceramics with Carbon Additions and Molten 42CrMo4 Steel

The formation of reaction layers between corundum‐based (Al2O3 + C) filter materials covered with functional Al2O3C coatings having different carbon contents and molten steel 42CrMo4 is investigated at the reaction temperature of 1600 °C. Within the first 60 s, an amorphous reaction layer is formed at the interface between the original filter surface and the molten steel. This layer consists mainly of Fe and O with small, varying amounts of Al and Si. After a longer contact time (120 s), nanocrystalline phases, which are identified as iron‐based oxides, formed within this amorphous interlayer. After 5 min, the amorphous interface layer is replaced by a dense corundum layer, on which thin corundum platelets are attached. The formation of the amorphous interface layer, its transformation to dense corundum, and the effect of the carbon content in the functional Al2O3C coating on the nucleation and growth of the corundum platelets are discussed. The reaction experiments are carried out in a spark plasma sintering device to avoid liquid metal convection and as immersion tests in a steel casting simulator to obtain relevant information about the filtering process.

Recovery of Au, Ag and Cu from printed circuit board leachate using activated carbon derived from foxtail fruit

Printed circuit boards (PCBs) are the e-waste generated from the end-of-life electronic equipment such as laptops and mobile phone. PCBs contain various metals including precious metals (gold, silver, copper) and detrimental heavy metals as well (arsenic, mercury) [9]. Recycling of e-waste is potentially to be one of the best mechanisms to overcome the human and environmental health threat hence, the valuable metals can be recovered and could avoid the depletion of our ore resources. In this paper, hydrometallurgical process on PCBs was carrying out to recover the precious metals. The PCBs were immersed into aqua regia leaching solution and later the targeted metals were leached out and extracted using activated carbon through adsorption process. The precious metals were then recovered by desorbing the spent activated carbon using hydrochloric acid (HCl) as desorbing agent. In this study, foxtail palm fruit was used to produce activated carbon for metals recovery process. Therefore, the objective of this study was to evaluate the efficiency of the prepared activated carbon derived from foxtail fruit for the recovery of Au, Ag and Cu contain in the PCB leachate. The effect of adsorbent dosage (1, 2, 3, 4, 5g), contact time (20, 40, 60, 80, 100 min) and desorption process of spent activated were investigated. The characterization of the prepared activated carbon was determined using field emission scanning electron microscope (FESEM) whereas the PCBs leachate solution before and after metal recovery process were quantified using flame atomic absorption spectrophotometer (FAAS). The obtained result showed that, the adsorption percentage of Au, Ag and Cu at high adsorbent dosage (5g) with longer contact time (100 min) were 65.51%, 30.30% and 62.51% respectively. However, the attained result for desorption percentage of the metals recovery for Au, Ag and Cu were recorded to be higher at shorter contact time (20 min) as the spent activated carbon could deteriorate at longer contact time with concentrated HCl. The percentage recovery values for 20 minutes desorption process were 99.77% (Au) when 5g of activated carbon was used, whilst 97.41% (Ag) and 98.83% (Cu) were obtained when 2g of activated carbon were applied, respectively. Thus, it can be concluded that the adsorption of Au, Ag and Cu were greater when higher dosage of activated carbon and longer contact time were applied. Meanwhile, shorter contact time were needed to recover the metals. Therefore, this study could be one of the finding in safeguarding our environment by minimizing the e-waste pollution as well as practicing metal recycling in community.

Peroxyacetic acid and chlorine dioxide unlike chlorine induce viable but non-culturable (VBNC) stage of Listeria monocytogenes and Escherichia coli O157:H7 in wash water

The elaboration of guidelines for the industry to establish minimum concentration to prevent cross-contamination during washing practices based on operational limits is the core of the recommended criteria for the use of sanitizers. Several studies have evidenced that sanitizers reduced the levels of foodborne pathogens. However, they might lead to the progress into a viable but non-culturable (VBNC) state of the cells. This evidence has raised concerns regarding the effectiveness of the recommended washing practices for the inactivation of microbial cells present in the process wash water (PWW). The present study evaluated if the most commonly used sanitizers, including sodium hypochlorite (chlorine), peroxyacetic acid (PAA) and chlorine dioxide (ClO2) at established operational limits induced the VBNC stage of Listeria monocytogenes and Escherichia coli O157:H7. Prevention of cross-contamination was examined in four different types of PWW from washing shredded lettuce and cabbage, diced onions, and baby spinach under simulated commercial conditions of high organic matter and 1 min contact time. The results obtained for chlorine showed that recommended operational limits (20–25 mg/L free chlorine) were effective in inactivating L. monocytogenes and E. coli O157:H7 in the different PWWs. However, the operational limits established for PAA (80 mg/L) and ClO2 (3 mg/L) reduced the levels of culturable pathogenic bacteria but induced the VBNC state of the remaining cells. Consequently, the operational limits for chlorine are satisfactory to inactivate foodborne pathogens present in PWW and prevent cross-contamination but higher concentrations or longer contact times should be needed for PAA and ClO2 to reduce the likelihood of the induction of VBNC bacteria cells, as it represents a hazard.

ADSORPTION OF Zn2+ ONTO UNMODIFIED AND CITRIC ACID MODIFIED GROUNDNUT SEED SHELL FROM AQEOUS SOLUTION.

This work studied the removal of Zn2+ from aqueous solution using unmodified and citric acid modified groundnut seed shell. Batch experiment was carried to ascertain the effects of adsorbent dose, particle size, and contact time on such adsorption with initial metal ions concentration of 100 mg/l at a temperature of 25 oC and pH of 7.5. It was deduced from the experiment that the amount of metal ion adsorbed increased as the adsorbent dose was increasing in both unmodified and citric acid modified ones; 97.27 mg/g at adsorbent dose of 4 g for the unmodified and 98.91 mg/g at adsorbent dose of 5 g for the modified. 250 µm and 354 µm were the optimum particle sizes for both unmodified and modified groundnut seed shell respectively, values given as 89.4 mg/g for the unmodified and 84.3 mg/g for the modified. Maximum adsorptions were all favoured at longer contact time; 90.31 mg/g at 120 minutes and 76.2 mg/g at 90 minutes for unmodified and modified, respectively. Generally, it was observed that the unmodified groundnut seed shell showed greater adsorption capacity than the modified groundnut seed shell. Lagergren’s first-order and Ho-McKay’s pseudo-second-order kinetics hypothesis were used to study the kinetic of metal ions adsorption onto unmodified and modified groundnut seed shell. It was observed that the removal of metal ions over the adsorbents showed a better fit with the pseudo-second-order process than the pseudo-first-order process with R2 values given as 0.957 and 0.967 for both unmodified and modified groundnut seed shell. Kinetics of Zn2+ adsorption obeyed the Pseudo-second order model which suggests chemisorption as the rate-determining step in adsorption process. Based on the results of the study, it was shown that the groundnut seed shell is capable of adsorbing Zn2+ from aqueous solutions especially when unmodified.

Gamma Knife radiosurgery and refractory glossopharyngeal neuralgia: a single-center series with long-term follow-up.

We present our experience with Gamma Knife surgery (GKS) and refractory glossopharyngeal neuralgia (GPN), analyzing its usefulness and safety in patients with or without previous surgeries, another concomitant neuralgia, or retreats. In addition, we study some factors that could condition the outcome of this technique. According to our review, our follow-up is the longest in the literature. We performed the prospective study of 8 patients submitted to GKS between 2008 and 2020. We employed the Leksell radiosurgery Gamma Knife system. The cases were evaluated before and after surgery (3, 6, 12months and then annually). The VAS (Visual Analogue Scale) and BNI (Barrow Neurological Institute) scale were used. The data were assessed with SPSS25. Our series was composed of 6 (75%) women and 2 (25%) men, with an average age of 59.5 ± 14.04years. Six patients (75%) had one or more than one previous surgeries. The median follow-up time was 7.22 ± 3.66years (1.08-12.5years). In the short-term postoperative period (1year), eight patients (100%) experienced significant pain relief (VAS, p = 0.012; BNI I-IIIb). After the last interview, 5 patients felt pain relief (62.5%) (BNI grade I = 3; BNI grade IIIa = 2); 3 patients (37.5%) (BNI grade IV) were retreated (MVD, 2; GKS, 1). We found no association between patients with long evolution time of disease (p = 0.356), previous surgeries (p = 0.206), or vascular contact (p = 0.673) and worse clinical results after GKS. Both morbidity and mortality were 0%. Our results suggest that GKS for treating drug-resistant GPN with high initial doses is both a minimally invasive and useful and effective therapeutic strategy, without permanent complications. It presents good results even in patients with one or more previous surgical interventions. These findings encourage us to use this non-invasive technique as initial therapy against the invasive options.

Adhesive Behavior of Propolis on Different Substrates

Propolis is a sticky substance used by bees to seal their hive and protect the colony against pathogens. Its main components are plant resins, beeswax, essential oils, pollen, and other organic substances. The chemical and medicinal properties of propolis have been extensively studied, but little is known about its physical and especially adhesive properties. To gain a better understanding of propolis and its potential for adhesive applications, we performed several experiments, including adhesion tests with propolis in different conditions and on various substrates, differential scanning calorimetry analysis, and compression tests. Propolis shows clear viscoelastic behavior and temperature-dependent mechanical properties. Our results demonstrate that propolis adheres well to a wide range of substrates from glass to PTFE, but also enables stronger adhesion at higher temperatures and longer contact times. Even underwater, in wet conditions, quite a substantial adhesion was measured. The data are interpreted from a biomechanical point of view, and the significance of the obtained results for bee biology is discussed.

Evidence for the transfer of methadone and EDDP by sweat to children\u2019s hair

In cases where there is a question as to whether children have come into contact with drugs, examinations of their scalp hair are frequently carried out. Positive test results are often discussed in the forensic community due to the various possible modes via which drugs and their metabolites can be incorporated into the hair. These include drug uptake by the child (e.g. oral ingestion or inhalation), but also contamination of hair via contact with the sweat from drug users. In this study, the possibility of methadone and its metabolite EDDP being incorporated into children’s hair by contact with sweat from persons undergoing opiate maintenance therapy (methadone) was examined. The transfer of methadone and EDDP via sweat from methadone patients (n = 15) to children’s hair was simulated by close skin contact of drug-free children’s hair, encased in mesh-pouches, for 5 days. Sweat-collecting patches (hereafter referred to as ‘sweat patches’) were applied to the test persons’ skin. One strand of hair and one sweat patch were collected daily from each patient. Analyses were performed using GC–MS/MS (hair) and LC–MS/MS (serum, sweat patches). After 4 days of skin contact, methadone was detectable in the formerly drug-free hair strands in all 15 study participants. EDDP was detectable in 34 of 75 hair strands, with the maximum number of positive results (11 EDDP-positive hair strands) being detected after 5 days. These results show that transfer of methadone and EDDP to drug-free hair is possible through close skin contact with individuals taking part in methadone substitution programmes. A correlation between serum concentration, sweat concentration and substance concentration in hair strands could not be demonstrated, but a tendency towards higher concentrations due to longer contact time is clearly evident.

Footstrike patterns and race performance in the 2017 IAAF World Championship men’s 10,000 m final

ABSTRACT Midfoot- (MFS) and forefoot-striking (FFS) runners usually switch to rearfoot-striking (RFS) during marathons. However, world-class runners might resist modifications during shorter races. The purpose of this study was to analyse footstrike patterns, ground contact times and running speeds in a World Championship men’s 10,000 m final. Footstrike patterns and contact times of the top 12 finishing men (24 ± 5 years) were recorded (150 Hz) during laps 1, 5, 11, 15, 20 and 25. Split times for each 100-m segment were obtained. No RFS patterns were observed; there was no difference between the number of FFS and MFS athletes at any distance (p ≥ 0.581) and no change in the proportions of FFS and MFS occurred (p = 0.383). No link between race performance and footstrike pattern appeared given the similar number who used FFS or MFS and their similar finishing times. Despite slower running speeds and longer contact times in the middle of the race (p ≤ 0.024), no effect on footstrike patterns occurred. The prevalence of anterior footstrike patterns in this world-class race reflects the capability of maintaining fast paces (>22 km/h). Changes in footstrike pattern might accompany the physiological and neuromuscular effects of fatigue over longer distances.

Analysis on medical observation of 1 665 close contacts of COVID-19 cases

Objective: To understand the identification and medical observation of close contacts of COVID-19 cases in a city and provide scientific basis for the adjustment of the epidemic prevention and control strategies. Methods: Descriptive epidemiological methods were used to analyze the general characteristics of all the close contacts of COVID-19 cases in a city. Throat swabs were collected from the close contacts for real-time fluorescent RT-PCR. The confirmed cases were diagnosed according to diagnosis and treatment of COVID-19 (trial version 5). Results: Among the 1 665 close contacts of COVID-19 cases in a city, 10 were diagnosed as COVID-19 cases during the medical observation period, accounting for 30.30% of all the confirmed cases in a city, most of them were close relatives of the confirmed cases. The longest contact time with the confirmed cases was 8 days and the shortest was 0 days. Ten COVID-19 cases in close contacts constituted to six family clusters. Conclusions: In COVID-19 prevention and control in a city, the active tracking of the transmission chains of the confirmed cases and timely identification of the close contacts were conducted. The people who had close contacts with the confirmed COVID-19 cases within 14 days before onset were all placed under medical observation, which played a key role in the effective prevention and control of COVID-19 epidemic in a city. Nearly one third of COVID-19 cases occurred during the medical observation period, so the infection sources were effectively controlled and transmission routes were effectively blocked, which greatly facilitated the prevention of the clusters of COVID-19 cases.

Effect of active resisted 30 m sprints upon step and joint kinematics and muscle activity in experienced male and female sprinters

ABSTRACT This study compared the kinematics (step and joint) and muscle activity of unresisted and active resisted 30 m sprints with different loads (10–40% body mass) in experienced male and female sprinters. Step kinematics were measured using a laser gun and contact mat in 28 male and female participants during unresisted 30 m sprint, and sprints with 10–40% of body mass (BM) active resistance, while peak angular velocities of lower limb was measured, together with muscle activation of nine muscles. Increased resisted loads resulted in slower 30 m times, as a result of lower step velocity mainly caused by shorter step lengths and frequencies, flight times and longer contact times, with a greater effect on women than on men. These step kinematic differences, due to increasing load were accompanied with lower peak joint movements. However, gender differences were only found for peak plantar flexion with unresisted and 10% BM resisted sprints. Furthermore, increasing load decreased calf and hamstring muscles activity, while medial vastus activity increased. Based upon these findings, it was concluded that when introducing active resisted sprints, women should sprint with approximately 10% less active loads than men to have equal step and joint kinematics development over the sprint distance.

Effectiveness and Reliability of Foot Orthoses on Impact Loading and Lower Limb Kinematics When Running at Preferred and Nonpreferred Speeds.

This study examined the effect of foot orthoses used on ground reaction forces, ankle, and knee kinematics when running at preferred and nonpreferred speeds. Sixteen runners ran on instrumented treadmills at various speeds (90%, 100%, and 110% of preferred speed) when wearing arch-support and flat-control orthoses. Two-way repeated analysis of variance (ANOVA) was performed on the mean and coefficient of variation of all variables. Results indicated that arch-support orthoses experienced larger maximum loading rates than flat-control orthoses (P = .017, 95% CI, 2.22 to 19.53). Slower speed was related to smaller loading rates (preferred: P = .002, 95% CI, -17.02 to -4.20; faster: P = .003, 95% CI, -29.78 to -6.17), shorter stride length (preferred: P < .001, 95% CI, -0.204 to -0.090; faster: P < .001, 95% CI, -0.382 to -0.237), and longer contact time (preferred: P < .001, 95% CI, 0.006-0.021; faster: 95% CI, 0.012-0.042). In arch-support condition, preferred speed induced higher stride length coefficient of variation (P = .046, 95% CI, 0.035-1.117) than faster speed, while displaying no differences in flat-control condition. These findings suggest that the use of arch-support orthoses would influence impact loading, but not spatial-temporal and joint kinematics in recreational runners.

Inactivation of Salmonella Typhimurium by Non-Thermal Plasma Bubbles: Exploring the Key Reactive Species and the Influence of Organic Matter.

The key reactive species generated by non-thermal plasma bubbles for the inactivation of Salmonella Typhimurium and the effects of organic matter on the inactivation efficacy were investigated. Plasma, which is primarily composed of ozone (O3), was generated by dielectric barrier discharge and injected into a solution (400 mL) as a bubble. The surviving population of S. Typhimurium decreased in proportion to the treatment time, resulting in a 5.29 log reduction after 5 min of treatment. Verification tests to specify key reactive species were conducted using an O3 destruction unit and reactive oxygen species scavengers. The results indicated that singlet oxygen (1O2) contributes substantially to the inactivation of S. Typhimurium, and that the presence of superoxide anion radicals (O2·−) from O3 is essential for the production of 1O2. When a S. Typhimurium suspension containing organic matter (final concentration: 0, 0.005, 0.05, 0.1, and 0.5 g/L), consisting of beef extract and peptone, was treated with plasma bubbles for 5, 10, 15, 20, 25, and 30 min, respectively, the potential of the plasma bubbles for inactivating S. Typhimurium successfully was verified with longer contact time, despite organic matter attenuating the inactivation efficiency in a dose-dependent manner.

A novel method for metals extraction from municipal solid waste using a microwave-assisted acid extraction

This paper investigated the development and evaluation of an extraction process for copper, chromium, cobalt, iron, manganese, zinc, lead, cadmium, barium, magnesium, and vanadium from municipal solid waste incineration ash (bottom and fly ashes) based on microwave-assisted acid extraction method. In this study, a novel conventional microwave-mediated technique was applied by using various acidic extracting agents, namely, hydrochloric acid, nitric acid, and phosphoric acid. Several experimental conditions and parameters were modified and optimized to determine the most effective conditions for maximizing metal extraction. The results were also compared with our preliminary research, which investigated the optimization of conventional heating for extracting the same metals. The current study concluded that the microwave-assisted acid extraction method was much more effective than conventional heating. The metals from the bottom ash were much easier to extract in contrast with the fly ash. For the bottom ash, 71 wt% of Co, 75.69 wt% of Cr, 56.19 wt% of Cd, 35.23 wt% of Ba, 30.2 wt% of Pb, and 5.41 wt% of Mn were effectively extracted using the protocol C (2 M HCl and 3 M H3PO4). 13.87 wt% of Al, 10.59 wt% of Cu, 7.2 wt% of Fe, 5.25 wt% of Mg were also extracted using the protocols D and E (3 M HNO3 and 3 M H2O2) from MSW-BA. On the other hand, for the fly ash, 2.27 wt% of Cu, 0.93 wt% of Fe, 2.32 wt% of Zn, 6.28 wt% of Cd, 1.98 wt% of Ba, 3.46 wt% of Mg and 4.7 wt% of V were extracted by using the protocol A (5 M HCl and 5 M HNO3). 1.48 wt% of Cr, 0.93 wt% of Fe, 1.19 wt% of Mn, and 1.18 wt% of Al were extracted using the protocol C (2 M HCl and 3 M H3PO4). It was also confirmed that higher microwave power levels had a positive effect on the metal extraction, and longer contact times had an adverse effect. When comparing the cost analyses for both methods, it was found that the microwave-assisted acid extraction was less expensive than the conventional heating. The present study offers a promising method, which is simple and cost-effective and presents a minimal environmental risk to extract metals from municipal solid waste incineration ash.

Effect of Approach Distance and Change of Direction Angles Upon Step and Joint Kinematics, Peak Muscle Activation, and Change of Direction Performance.

The aim of the study was to compare the step kinematics, joint angles, and muscle activations between change of direction (COD) maneuvers with different angles and approach distances, suggested to require different strength and velocity demands. Twenty-three male soccer players completed eight COD tests consisting of both 4 and 20-m sprint approaches with one directional change which varied between each COD test (45, 90, 135, and 180°). Peak muscle activity, step and joint kinematics of the lower limbs of the plant, and re-acceleration step were measured. Compared to 4-m CODs, the 20-m COD approach distances increased vertical center of mass displacement (p < 0.001), number of deceleration steps (p < 0.001), revealing no statistical differences upon joint angles (p > 0.05). Greater COD angles resulted in increased ankle dorsiflexion, hip abduction and flexion, greater displacement of the center of mass and tibia angle, longer contact times, and more deceleration steps (p < 0.034). The CODs categorized as velocity-dominant revealed higher peak muscle activity in the adductor longus, semitendinosus, biceps femoris, and gastrocnemius. It was concluded that velocity-dominant CODs revealed higher muscle activity due to a higher eccentric loading, implicating task-specific training considerations for enhancing COD performance.

Post-impact dynamics of droplet on bare stranded overhead power transmission lines with varying surface properties

Overhead transmission lines are the most key component in power transmission systems, the bare transmission lines with stranded conductors are the main type for long-range power transmission. However, the long range makes the transmission lines easily be affected by rain icing problem in winter or cold regions, therefore the understandings of how the rain droplet interacting with surfaces of this kind of transmission lines are significant. By using many-body dissipative particle dynamics, the present work simulates the droplet impact on the stranded conductors with varying surface properties, such as surface wettability, number of strands, and twist pitch. The simulation results show that hydrophilic surfaces can retain most of the liquid while the superhydrophobic ones can repel most liquid after impact. A large number of strands, which means a large size of grooves, will force the liquid to flow along the grooves after impact. In this circumstance, grooves on surfaces with short twist pitch can guide the liquid to flow to a more downward direction, while grooves on surfaces with long twist pitch can guide the liquid flow closer to the axial direction of the transmission line and retain more liquid on the surface after impact. Besides, for bouncing cases, longer twist pitch can cause longer contact time.

Cr(VI) Removal Using the Combination of the Cr(VI)-Resistant and Cr(VI)-Reducing Biofilm and the Alum-Polyacrylamide

This paper describes the removal of Cr(VI) using the combination of bacterial reduction of Cr(VI) to Cr(III) by wood husk–packed column containing the Cr(VI)-reducing biofilm followed by Cr(III) removal using the coagulation-flocculation technique. The chromium removal process was carried out at the laboratory-scale for 90 days using different batches of Cr(VI) ranging from 35 to 231 mg L−1. Analysis of variance (ANOVA) showed a high coefficient of determination (R2) value of 0.9941, thus ensuring a satisfactory adjustment of the second-order regression model with the experimental data. The experimental observations were in reasonable agreement with the modeled values. The biofilm was able to completely reduce 100 mg L−1 Cr(VI) in 6 h while a longer contact time (18 h) was needed for higher Cr(VI) concentrations. In this study, ORP (oxidation-reduction potential) was used as the control parameter during the Cr(VI) reduction process. The coagulation/flocculation process using the combination of alum and polyacrylamide results in complete removal of color, 85% Cr(III), and 97% turbidity. The field emission scanning electron microscope (FESEM) analysis of the biofilm revealed the embedding of bacterial cells in extracellular polymeric substances (EPS). This study successfully demonstrated the potential application of a bacterial biofilm and chemical systems to remove chromium contamination from water systems.