Total Contact Time Research Articles

Developing a Novel Contact Tracing Mobile Application for Coronavirus Disease 2019 (COVID-19) for Improving Testing Capacity and Controlling the Spread of COVID-19 in Nigeria

In this study, a novel contact tracing model that leverages smartphone technology to enhance efficiency, reduce costs, and extend the duration of contact tracing efforts is developed. This model utilizes smartphones as identification systems, collecting data on the proximity of other smartphone users through integrated Bluetooth and GPS technology. The study examines the frequency, duration, and proximity of interactions between smartphone devices in a clinical setting, highlighting potential implications for infectious disease transmission to pilot the mobile application developed. Contact data from six pairs of devices were analyzed, focusing on metrics such as total contacts, total contact time, average contact time, average distance, and the percentage of contacts occurring within 1.5 meters. The results showed varying levels of interaction across device pairs, with Devices 1 & 3 showing the highest number of contacts (175), and Devices 3 & 4 displaying the longest average contact time (20,133,193.01 seconds). Correlation analysis revealed weak and statistically insignificant relationships between total contacts and average distance (r = 0.13, p = 0.81), contact time and the percentage of close contacts (r = -0.15, p = 0.78). These findings suggest that while there are observable trends in contact patterns, the statistical insignificance highlights the need for further investigation to establish stronger associations that could inform infection control practices in healthcare settings.

Current Formulation Strategies to Design Novel Carriers for Targeted Drug Delivery and Management of Infectious Keratitis: A Comprehensive Review on the Present State of the Art

Objective: Infectious keratitis is a pernicious disease that affects the anterior segment of the eye and is one the leading causes of blindness worldwide. This disease may cause severe visual impairment or permanent vision damage if left untreated. Discussion: No doubt there are many conventional drug delivery systems to treat ocular keratitis, yet it is the fifth leading cause of blindness globally. This is the result of the eye's complex anatomy and barrier system, which restricts the total ocular contact time of the conventional formulations resulting in underdosing. The widely used traditional formulations to treat keratitis, like antibiotic eye drops and ointments, are rendered useless due to less ocular contact time and low therapeutic drug levels at the target ocular site. The main requirement of the present time is to develop novel drug delivery-backed stratagems to overcome the shortcomings of conventional formulations, which will reduce the morbidity associated with infectious keratitis and improve clinical outcomes. It is worth mentioning that there are documented incidents of Herpetic keratitis of the cornea followed by COVID-19 infection and vaccination. Conclusion: This paper is a rigorous review of all the novel drug delivery strategies to combat ocular keratitis. These future drug delivery strategies will pave the way for the present time researcher and formulation chemists to develop multi-dimensional novel formulations that are safe, patient-compliant, and surpass the ocular barriers to maintain therapeutic drug levels in ocular tissues.

Influence of the Beiring Sorenson Hold and the Barbell Back Squat on Running Cadence in Military Ruck Marching: A Cross-Sectional Observational Study

Ruck marching is a key performance indicator for tactical preparation; however, marching under load causes changes in biomechanics, which can increase injury risk. Although this risk of injury from changes is known, current methods commonly used for assessing physical fitness have not adequately identified how to minimize these changes. In this observational study, 14 ROTC cadets underwent a series of physical muscular fitness tests prior to performing a six-mile ruck march. These included an evaluation of postural endurance via the Biering Sorenson hold, lower body strength via the back squat, and upper body strength via bench press. After the tests were performed, ruck march performance was evaluated by total time to completion and running dynamics. Multiple regression analysis was performed to determine if bench press maximum, back squat maximum, or Sorenson hold were predictors of the performance of the ruck March. Average cadence shared a positive significant relationship with the Sorenson hold (r = 0.76, p = 0.02) and a negative significant relationship with the back squat (r = -0.76, p = 0.02). Additionally, the Sorenson hold did not share any significant relationships with total ruck time (r = -0.3, p = 0.29) or ground contact time (r = -0.41, p = 0.31). The back squat did not share significant relationships with ground contact time (r = -0.37, p = 0.37) or average smoothness (r = -0.38, p = 0.31). This study highlights the potential relationship that the Sorenson hold and back squat can have on running cadence, which has shown significant changes in previous research evaluating the changes in running performance and characteristics from weight ruck marching. Further investigation of the relationship of these assessments on the performance of ruck marching should be performed with larger numbers of cadets in the future.

An analysis of the contact time of nanodroplets impacting superhydrophobic surfaces with square ridges

Reducing the contact time between liquid droplets and solid surfaces is important in numerous engineering applications. Mechanisms for reducing the contact time have been extensively studied. However, there is still a lack of systematic research on the mechanisms governing the changes in the contact time of nanodroplets impacting superhydrophobic surfaces with square ridges. Additionally, there has been relatively little examination of the differences between nanodroplets and macroscopic droplets in this scenario. In this work, we investigate the impact of nanodroplets on both superhydrophobic planes and superhydrophobic surfaces with square ridges. When nanodroplets impact a superhydrophobic plane, we find that the droplet contraction time determines the total contact time. When nanodroplets impact superhydrophobic surfaces with square ridges, we find for the first time that the critical factor determining its contact time is the detachment time of the droplet from the square ridges as it lifts off. Compared to millimeter-sized droplets, nanodroplets exhibit stronger adhesion to solid surfaces. Additionally, we propose for the first time that nanodroplets are more resistant to deformation and splitting. We define the Weber number (We) at which the droplet rebounds as the critical rebound Weber number (We), and use this to evaluate the effect of square ridges on improving droplet rebound. We observe that a moderate increase in the square ridge height is beneficial to reducing the contact time. By altering the square ridge width, we find that a narrower ridge is more favorable for reducing the contact time and for facilitating droplet splitting.

Comprehensive profiling of social mixing patterns in resource poor countries: A mixed methods research protocol.

Low-and-middle-income countries (LMICs) bear a disproportionate burden of communicable diseases. Social interaction data inform infectious disease models and disease prevention strategies. The variations in demographics and contact patterns across ages, cultures, and locations significantly impact infectious disease dynamics and pathogen transmission. LMICs lack sufficient social interaction data for infectious disease modeling. To address this gap, we will collect qualitative and quantitative data from eight study sites (encompassing both rural and urban settings) across Guatemala, India, Pakistan, and Mozambique. We will conduct focus group discussions and cognitive interviews to assess the feasibility and acceptability of our data collection tools at each site. Thematic and rapid analyses will help to identify key themes and categories through coding, guiding the design of quantitative data collection tools (enrollment survey, contact diaries, exit survey, and wearable proximity sensors) and the implementation of study procedures. We will create three age-specific contact matrices (physical, nonphysical, and both) at each study site using data from standardized contact diaries to characterize the patterns of social mixing. Regression analysis will be conducted to identify key drivers of contacts. We will comprehensively profile the frequency, duration, and intensity of infants' interactions with household members using high resolution data from the proximity sensors and calculating infants' proximity score (fraction of time spent by each household member in proximity with the infant, over the total infant contact time) for each household member. Our qualitative data yielded insights into the perceptions and acceptability of contact diaries and wearable proximity sensors for collecting social mixing data in LMICs. The quantitative data will allow a more accurate representation of human interactions that lead to the transmission of pathogens through close contact in LMICs. Our findings will provide more appropriate social mixing data for parameterizing mathematical models of LMIC populations. Our study tools could be adapted for other studies.

Do lower limb kinetic and kinematic differences in drop jump landings persist when players have returned to sport following knee ligamentous injuries?

Knee injuries (KI) are identified as one of the most burdensome lower limb injuries in football with long and complicated rehabilitation and high re-injury risk. Current research often describes technique deficits being present upon RTS, often being a result of poor return to sport (RTS) testing procedures. More recently, research has advocated the use of single leg vertical jump assessments, due to the specificity of the movement to injury mechanisms and the ability to consider different phases of the task to inform practitioners of joint contributions to the propulsion and landing phases. The aim of this research is to identify whether these functional deficits exist 12-24 months post RTS authorisation, to help inform future RTS in applied practice. Twenty-four semi-professional male footballers (mean ± SD: age 25 ± 4 years; stature 182 ± 7 cm; body mass 80 ± 8 kg) were recruited into a previously injured and a control group. Participants completed 5 repetitions of single leg drop jump (SLDJ). Jump height, ground contact time, reactive strength index, peak moments, angles and power contributions for the hip, knee and ankle were measured using Qualisys Track Manager then exported to Visual 3D. This study was approved by the Edge Hill University Ethics Committee. No significant findings were identified for landing one however, during the propulsion phase there was a difference between groups (P = 0.026, d=1.14) for knee flexion at take-off. Most differences were identified during landing two bilaterally in both groups. Within the injured group, differences were identified for peak hip (P = 0.011, d = 0.028) and knee powers (P < 0.001, d = 1.269), hip (P < 0.001, d = 1.924) and knee power contribution % (P < 0.001, d = 1.269). No differences were identified for the performance measures or through performing statistical parametric mapping for hip and knee powers for all three phases. Joint coupling analysis was conducted for the total ground contact time amalgamating the landing and propulsion phase, this was analysed as Hip-Knee, Hip-Ankle and Knee-Ankle, with significant findings in Hip-Knee and Hip-ankle. Both groups elicited bilateral differences however, no differences between the injured limb and dominant control limb were identified. To better apply this form of analysis to RTS testing, functional movements such should be undertaken when athletes are injury free to provide baseline measurements to refer to if undertaking rehabilitation from KI. Likewise, the current study identified that joint contributions could be identified in a more applied setting using the range of motion data from each joint.

Long-term consumption of rooibos herbal tea affects hypothalamic neurotransmission and social behavior of adult Sprague–Dawley male rats

Abundant in phenolic compounds, “fermented” rooibos herbal tea (FRHT) improves the cognitive performance and exploration of rats, as well as alters the content of monoamines and amino acids in some brain structures. Here, we aim to extend knowledge about the neurochemical and behavioral outcomes of long-term oral FRHT consumption by examining its impact on hypothalamus functions. FRHTs of different leaf-to-water ratios were given to adult male SD rats for 3 months. Their behavior was evaluated in social interaction test. The concentration of hypothalamic monoamines and amino acids was analyzed by HPLC-ECD whereas BDNF/TrkB by Elisa method. It was shown that sustained FRHT consumption did not affect aggression of the rats but was able to increase social deficits, expressed as diminished total time of contact and shorter active social interaction. Upon biochemical investigation, the changes were primarily linked to serotonergic, glutaminergic, and BDNF/TrkB pathway. Decreased 5-HT and TrkB content in the hypothalamus could be linked with social deficits and suggested positive effect on central energy balance, yet the main body mass of animals in the experiment remained unaffected. On the other hand, the reduced hypothalamic serotonin signaling anticipated the influence on hypothalamic–pituitary–adrenal axis and possible diminution of plasma corticosterone level with subsequent behavioral aftermath and lower obesity risk. Our research contributes toward better understanding of the mechanism of action of rooibos tea and its effects within the central nervous system.Graphical abstract

Rate dependence in adhesive particle–particle contacts affect ceramic suspension bulk flow behavior

Particle–fluid mixtures are known for displaying a wide variety of interesting flow mechanisms, such as thickening and thinning under shear. It is now becoming increasingly evident that even molecular scale effects are relevant for this macroscopic flow behavior of suspensions. Here we show that even 50μm ceramic beads in a non-density matched solvent are affected by the pH of the solvent. We trace the origin of the pH dependence to the contact mechanics using colloidal probe atomic force microscopy (CP-AFM). The gel-like structure of the pH 3 samples suggests that adhesion effects play a major role, but which adhesion timescale competes with shear rate to affect the rheology is not obvious. We test here two time scales in the contact mechanics: total contact time tc and contact retraction speed vr. We observe that contact time is the most important variable to correlate with rheology. The ceramic particle suspension so serves as a model system to help understand which adhesive mechanism affects flow behavior in the suspension.

Comparison of ground reaction force and contact time during various-direction lunges between badminton shoes without and with a lateral forefoot wedge sole

This study compared the ground reaction force (GRF), GRF ratio, and contact time between badminton shoes without and with a lateral forefoot wedge sole during lunges in three directions. Fifteen collegiate athletes wore forefoot wedge shoes (5° incline) and control shoes without a lateral forefoot wedge sole (in random order) and performed three typical badminton lunge movements (forward, lateral, and backward directions). A total of nine GRF, GRF ratio, and contact time parameters were analyzed. A paired t test was performed to assess the differences between two shoes. The significance level was set at p < 0.0056 (0.05/9) based on Bonferroni correction to avoid chances of type 1 errors. In the forward lunge, the forefoot wedge shoes resulted in a significantly higher average vertical ground reaction force (GRFv, 3.9%), average horizontal GRF (GRFh, 7.8%) in the braking phase and higher average GRFh (3.9%) in the propulsion phase than the control shoes. In the lateral lunge, the forefoot wedge shoes resulted in a significantly shorter total contact time (−4.6%) than the control shoes in the backward lunge, the forefoot wedge shoes resulted in a significantly higher GRFh to GRFv ratio (6.4%) in the braking phase compared with the control shoes. Thus, shoes with a lateral forefoot wedge sole can effectively enhance mechanical performance in direction changes during forward and backward badminton lunges, and shorter the contact time during lateral badminton lunges. Shoes with a lateral forefoot wedge sole can be considered when designing athletic footwear.

Quality of Life, Pedobarographic Parameters, and Foot Disorders in Patients with Extreme Obesity: Preliminary Results on Changes After Bariatric Surgery with Gastric Bypass

PurposeObesity is a growing health problem that affects a high percentage of the population. In podiatry context, few studies have addressed obesity because most pedobarographic systems are unable to bear the weight of patients with obesity, making it difficult to examine and manage these patients. The objective of this study was analyzed the sociodemographic characteristics, quality of life, foot disorders, and pedobarographic parameters of patients with extreme obesity who are candidates for bariatric surgery and determine the changes after weight loss post-surgery.Materials and MethodsWe conducted a foot examination, a pedobarographic study using a Podoprint® pressure platform, and a quality of life questionnaire (EQ-5D) on 23 patients with extreme obesity and analyzed the changes 12–18 months after surgery in 11 of them.ResultsWe observed foot disorders, high plantar pressure, greater rearfoot contact, flat footprint, asymmetries, and alterations in toe contact. Almost 73.9% of participants said they had foot pain, 56.5% said they had impaired mobility, and more than 40% said they had limitations in carrying out daily activities and suffered from anxiety. After weight loss, we observed improved quality of life; more foot disorders; changes in total contact area, plantar pressures, barycenter, contact time, and footprint; decreased pain perception, walking problems and anxiety situations. Moreover, medication decreased, but they need to take more vitamins and calcium.ConclusionWeight loss improved the quality of life of the participating patients but altered their foot disorders. All parameters need regular reassessment to detect changes and modify initially prescribed treatments.Graphical

Relaxation phase during droplet impact on superhydrophobic surfaces with high contact angle hysteresis

The droplet impact process on a solid surface is divided into a spreading phase where the droplet reaches the maximum deformation followed by a retracting phase. However, in the case of surfaces with high contact angle hysteresis, these two phases are connected by a relaxation phase where the contact angle changes from the advancing to the receding contact angle almost without motion of the contact line. Although the relaxation time can represent a significant part of the total droplet contact time, this relaxation regime has been less explored, especially for superhydrophobic surfaces due to the challenge of designing such surfaces with controlled wetting properties. Here, we show that for superhydrophobic surfaces with large contact angle hysteresis, the relaxation time can be comparable to the spreading and retracting time. Our results indicate that both the contact angle hysteresis and the capillary forces play a major role in defining the relaxation time and that relaxation time scales with the inertial–capillary time when using the droplet relative deformation as the characteristic length scale for this relaxation regime.

Quantifying unmet need in General Practice: a retrospective cohort study of administrative data

ObjectivesTo assess whether patients attending general practices (GPs) in socioeconomically (SE) deprived areas receive the same amount of care, compared with similar patients (based on age, sex and level of...

Universality of Scaling Laws Governing Contact and Spreading Time Spans of Bouncing Liquid Marbles and its Physical Origin.

The impact of liquid marbles coated with a diversity of hydrophobic powders with various solid substrates, including hydrophobic, hydrophilic, and superhydrophobic ones, was investigated. The contact time of the bouncing marbles was studied. Universal scaling behavior of the contact time tc as a function of the Weber number (We) was established; the scaling law tc = tc(We) was independent of the kind of powder and the type of solid substrate. The total contact time consists of spreading time and retraction time. It is weakly dependent on We and this is true for all kinds of studied powders and substrates. This observation hints to the surface tension/inertia spring model governing the impact. By contrast, the spreading time ts scales as [Formula: see text], n = 0.28 - 0.30 ± 0.002. We relate the origin of this scaling law to the viscous dissipation occurring within the spreading marbles. The retraction time tr grows weakly with the Weber number. The scaling law was changed at threshold values of We ≅ 15-20. It is reasonable to explain this change with the breaking of the Leidenfrost regime of spreading under high values of We.

Age, Gender, Body Mass Index, and Foot Loading During Gait.

The aim was to analyze changes in normal functional parameters of gait analysis by aging, sex, and body mass index (BMI). 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. 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). 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. Level III, diagnostic and prognostic.

EFFECT OF MECHANICAL ACTIVATION ON THE POTASSIUM AVAILABILITY OF PHONOLITE ROCK

Background: Researchers are carried out to assess rocks containing potassium as an alternative source of fertilizers. These studies are important in reducing the external dependence of Brazil on this commodity. Phonolite is a rock of volcanic origin that has in its mineralogical composition the predominance of feldspar and has been potential to use as an alternative potassium source. The studied rock has 6% total-K but is unavailable to plants in natural rock. Aim: This project evaluated the effect of mechanical activation, wet and dry, on K availability for extractors different and its K leaching curves of phonolite from Poços de Caldas, MG, Brazil. Methods: Phonolite rock was subjected to mechanical activation for 30 and 60 min by wet and dry processes. Particle size distribution, XRD, and FTIR analyses characterized phonolite activated. These results were compared to the behavior of the rock with no activation. K availability (total; water-soluble; exchangeable, non-exchangeable, and structural) was determined in samples activated and no activation. K leaching curves were obtained by successive extractions with 0.01 mol L-1 citric acid and Mehlich-1 solutions to 1812 h and analyzed by FAAS. Results: The samples mechanical activation promoted a reduction in the intensity of the diffraction peaks. In the sample dry mechanical activation for 60 min, K released increased by 15% in relation to the no activation sample. K leaching curves were observed with similar behavior for the extractors and higher K availability after 235 h of total contact time. Discussion: Mechanical activation promoted a decrease in structural K and an increase in non-exchangeable K, released into the soil solution in the medium term. Since the mineralogical composition was not changed, the process action is more efficient in creating the structural defects suggested. K leaching curves corroborate these results, with a continuous and slow K released for a longer contact time. Conclusions: It was concluded that the phonolite activated by dry mechanical activation for 60 min increased K-released content compared with the wet process and ratified the possibility of the activated phonolite rock as a slow-release fertilizer.

Antioxidant properties and antibacterial activity of water extracts from Sambucus nigra L. under different conditions

In folk medicine, dried white flowers of Sambucus nigra L. are used to make infusions, decoctions, and juices. The present article aims to study and compare the antioxidant activity of aqueous solutions of leaves and flowers of Sambucus nigra L obtained at different exposure times and assess the antibacterial activity of these solutions against Escherichia coli ATCC 8739, Salmonella NCTC 6017, Listeria monocytogenes NCTC 11994, and Staphylococcus aureus ATCC 25093. We studied the physicochemical properties of aqueous extracts of leaves (fresh) and flowers (fresh and dry) of Sambucus nigra L collected from the Rhodope region of Bulgaria. The samples from Sambucus nigra L were analyzed to determine their total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP). The diameters (in millimeters) of the growth inhibition zones of four pathogens were measured, and a comparative assessment of their antibacterial activity was made. The infusions of fresh blossoms and fresh leaves of Sambucus nigra L had the highest antioxidant activity at the total contact time of 30 minutes (82.7mmol TE/100ml) and 35 minutes (36.5mmol TE/100ml), respectively. The phenol-richest infusions were those made from dried flowers of Sambucus nigra L after a 30-minute contact time (86.7mg GAE/ml). Of the four pathogens we studied, we found that the extracts affected partially only the pathogenic bacteria of Salmonella. The highest content of bioactive components was obtained from dried blossoms of Sambucus nigra L. for infusions with a total contact time of 30 minutes and for decoctions at a contact time of 45 minutes.

Polycyclic aromatic hydrocarbon (PAH) leachates from post-consumption waterpipe tobacco waste (PWTW) into aquatic environment- a primary study

Post-consumption waterpipe tobacco waste (PWTW) is an unrecognized type of hazardous waste that is produced and released in large quantities into the aquatic environment. It may contain high amounts of various pollutants including PAH, and to date, there has been no research on the potential for contamination by PAH from PWTW leaching into aquatic environments. In this study, the concentrations of PAH via PWTW of fruit-flavored and traditional tobacco leachate into three water types, including distilled water (DW), tap water (TW) and sea water (SW) at different contact times were evaluated. There were significantly higher concentration levels of ƩPAH in waters with leachates from fruit-flavored PWTW than traditional tobacco (P-value<0.05). The concentration levels of ƩPAH in DW, TW and SW at a total contact time of two months ranged from 0.13 to 3.51, 0.12 to 3.63 and 0.11–3.64 μg/L, respectively. Lower molecular weight PAH such as naphthalene (Naph), acenaphthylene (Acen) and fluorine (Flu) were detected in leachates immediately after a short contact time of 15 min. Higher molecular weight PAH including benzo [a]anthracene (BaA), benzo [b]fluoranthene (BbF), benzo [k]fluoranthene (BkF), chrysene (Chr), and benzo [a]pyrene (BaP) were detected after one month contact time, while indeno [1,2,3-cd] pyrene (Indp), benzo [ghi]perylene (BghiP) and dibenz [a,h]anthracene (DahA) were only observed at the contact time measurement of two months. By adding sodium azide as an antimicrobial agent and chemical preservative to SW samples, higher concentrations of PAH including IP, DahA and BghiP were observed. The concentration levels of PAH in water samples after two months contact time were higher than water quality standards provided by the World Health Organization (WHO) and other international organizations.

A numerical investigation of droplet bouncing behaviors on the superhydrophobic surfaces with different micro-structures

Better understanding of the droplet bouncing behaviors and microscopic mechanisms on superhydrophobic surfaces is of significance for a large number of energy applications. In this study, the bouncing process of droplets on superhydrophobic surfaces was investigated by lattice Boltzmann method (LBM). Four types of micro-structures for superhydrophobic surface were investigated: perfectly smooth surface, perfectly regular surface, randomly regular surface, and randomly rough surface. Random rough surfaces were described by skewness (−0.9 to 0.9), kurtosis (1.0–5.0) and standard deviation (0.3–1.1). The basic morphology and roughness parameters of the randomly rough surfaces were obtained by atomic force microscopy (AFM) and was developed by numerical reconstruction method. After the experimental verification, the droplet bouncing characteristics on the superhydrophobic surface with different micro-structures are compared and summarized. The maximum spreading length, the contact time and post-bounce morphology of droplet bouncing process are analyzed. It was found that the maximum spreading length of the droplet is reduced with the increasing of surface skewness, kurtosis and standard deviation. In the random regular surface, the increase of parameters from minimum to maximum reduced the maximum spreading length by 8.22%. The total contact time increased by 16.61%. When the number of surface sharp edges are smaller or the groove-like structures are wider, the contact time of droplet bouncing process can be obviously reduces. The droplet has the best bouncing performance on superhydrophobic surface that satisfy a skewness of 0.3–0.5, kurtosis of 3.0 and standard deviation of 0.7–0.9. The dynamic processes study of the droplets on surfaces with four gradations of roughness has not been done before. The gradual roughness can reflect the change process from theoretical superhydrophobic surfaces to practically prepared superhydrophobic surfaces with droplet bouncing. We have discovered a new law of droplet bouncing from progressively more complex surface microstructures. The main contribution of this work is to give simulation data of droplet bouncing on four surfaces simultaneously. The most suitable surfaces for bouncing are compared and conclusions are drawn. The influence of different surface micro-structures on the droplet bouncing behaviors obtained in this paper may be useful for the optimal design of superhydrophobic surface.

Optimal Drop Height in Prepubertal Boys Is Revealed by the Performance in Squat Jump.

Drop jump (DJ) performance gain with increasing drop height is well documented in adults, but there is still no clear evidence of such gain in children. This study aimed to examine the differences in DJ performance gain in male adults and prepubescent boys by comparing drop heights tailored to each individual's performance and expressed as a percentage of their squat jump (SJ) performance. Fifteen boys (9-11 y) and 15 men (19-27 y) executed DJs from drop heights that were set at 75%, 100%, 125%, and 150% of their best performance in SJ (DJ75, DJ100, DJ125, and DJ150, respectively). Vertical ground reaction force (vGRF), contact time and kinematics of the lower extremities were captured. The results showed that boys jumped significantly lower than adults in DJs, and both age groups presented jumping gain with increasing drop height, up to DJ125. Boys demonstrated longer total contact time, lower angular velocity and vGRF during the propulsive phase, as well as smaller knee flexion at touchdown and lower reactive strength index. vGRF in DJ75 and DJ100 was lower than in DJ125 and DJ150. The highest value for maximum knee flexion was also presented at DJ150. It is concluded that in prepubescent boys, the appropriate drop height for an effective DJ is linked to their performance in SJ and might be between 75% and 125% of their maximum SJ performance.

YENİLİKÇİ KENDİNDEN İYİLEŞEN HİDROJEL KOMPOZİT OLARAK AZOT KATKILI KARBON KUANTUM DOTS-GELLAN GUM

Tension sensors can be widely applied to detect body movements and monitor physiological signals. Hydrogels with conductive properties draw attention among the studies in this field. However, their application is limited because hydrogels can be easily damaged during use. In this study, a self-healing conductive hydrogel was produced by adding nitrogen-doped carbon quantum dots (NCQDs) to gellan gum (GG) polymer. The self-healing property of the hydrogen bonds in the prepared polymeric matrix network to a certain extent and the conductivity were supported by the addition of NCQDs. The electrical recovery process of the hydrogel in the 1, 2, and 3 cutting/healing cycles was illustrated by a visually designed LED bulb serial circuit. As a result of connecting the obtained 3D hydrogel to a real-time resistance change measurement system, the resistance changes in the cutting/healing cycles were monitored. The duration of the total cut-healing process, including cut and contact time, was 2.12 s. In addition, a free-standing gel bridge was formed after joining the two cut pieces of cylindrical hydrogels. Due to the resulting hydrogel composite properties, it has promising potential in various applications such as personal health diagnosis, human activity monitoring, and human-motion sensors.