Final Contact Research Articles

Effect of Cr, Al and Mo additives on the wetting characteristics of molten Ni on (Ti, Zr, Hf, Nb, Ta)C high entropy ceramics

For the first time, the wetting behavior of the (Ti, Zr, Hf, Nb, Ta)C) high entropy carbide ceramics by molten Ni-based alloys was investigated using a sessile drop technique in a vacuum environment. Adding 10wt% of Cr, Mo, or Al into Ni resulted in final contact angles of 14°, 10°, and 14° on the (Ti, Zr, Hf, Nb, Ta)C substrate, respectively. The interaction mechanism between (Ti, Zr, Hf, Nb, Ta)C and Ni-based alloys occurs in two stages: the dissolution and interaction of the elements Ti, Zr, Hf with the alloys and the dissolution of NbC and TaC at the grain boundaries. SEM observations revealed that Cr and Al additives do not interact with carbides, while Mo was dissolved in carbides. Due to the low contact angle, minimal interaction region between alloy and ceramic, and short time of drop spreading, NiAl alloy is proven to be a promising binder for the HEC-based composites.

Partner Characteristics and HIV Outcomes among Partners Reached by Phone vs. In-person for Assisted Partner Services in Western Kenya.

Assisted partner services (APS) is an effective strategy for testing people with undiagnosed HIV but there is limited information on the relative reach and effectiveness of phone versus in-person contact. We analyzed data from 31 facilities in Western Kenya providing APS to female index clients newly HIV-diagnosed, their male partners, and female partners of men newly HIV-diagnosed. APS providers attempted contacting partners using phone first and, if unsuccessful, in-person in the community. Using log-linear mixed models, we estimated relative risks (RR) between phone being the final contact method and partner characteristics and HIV outcomes. From May 2018-March 2020, 2534 female index clients named 7614 male partners, of whom 772 (10.1%) tested positive and named an additional 4956 non-index female partners. Of 11,912 (94.7%) partners reached, 5179 (43.5%) were via phone and 6733 (56.5%) in-person. Of 8076 testing-eligible partners, 99.7% tested and 11.2% first-time tested. Of those tested, 13.1% were newly-diagnosed, of whom 87.0% linked to care. Newly-diagnosed partners were less likely to have been reached by phone vs. in-person (9.8% vs. 15.9%; adjusted RR:0.61, 95%CI:0.53-0.70). Being reached by phone was not significantly associated with testing, first-time testing, or linkage to care. In an APS program that reached 94% of elicited partners, fewer than half were successfully contacted by phone. A combined phone and in-person approach is likely essential for equitable, effective APS.

Wetting behavior of Ti-Ni-xNb filler alloy on (HfTaZrNbTi)C high-entropy carbide ceramic

Exploring the wetting behavior of active filler alloys on high-entropy ceramic is critical to clarifying the solid/liquid interface reaction mechanism and guiding the preparation of high-performance composites. The wetting and spreading behaviors of the molten Ti-Ni-xNb filler alloys, both without and with different Nb concentrations, on (HfTaZrNbTi)C high-entropy carbide (HEC) ceramic were investigated at 1330 °C under a vacuum atmosphere using a sessile drop method. The wetting process of the Ti-Ni-xNb filler alloys was characterized by four distinct stages: (i) adhesion stage, (ii) rapid decreasing stage, (iii) sluggish spreading stage, and (iv) final equilibrium stage. The Ti-Ni-xNb filler alloys all exhibited good wettability on the HEC ceramic, with the final contact angle remaining around 47-48°. The interfacial structure was identified as a sequence of HEC/Ti-based HEC’ diffusion layer/TiCx reaction layer/Ti2Ni layer/alloy droplet in all wetting systems. Notably, the introduced Nb element participated in the interfacial reactions between HEC and the filler alloy, modifying the morphology of the solidified droplet and accelerating the rapidly decreasing stage of the alloys on the ceramic. Nb atoms replaced some of the Ti atoms in the TiCx reaction layer, which restrained the atomic diffusion, leading to the formation of thinner reaction layers. The spreading kinetics were initially governed by interfacial reactions and later by the diffusion of Ti and Ni into the ceramic substrate, exhibiting a transition from reaction-controlled to diffusion-controlled spreading.

Sistem Informasi Bimbingan Tugas Akhir Mahasiswa menggunakan Model SDLC Berbasis Iconix Process

The final thesis assignment plays a crucial role in enabling students to meet the graduation requirements from college. However, the process of scheduling guidance for the final assignment between students and lecturers still relies on several common applications such as WhatsApp or email, which are not specifically designed for this purpose. The accumulation of incoming messages and various types of message information poses a challenge in the guidance process, leading to missed messages between students and lecturers and a lack of recorded information regarding the history of the process and guidance materials. These are some of the current issues. This paper aims to evaluate the functionality, quality, and reliability of the system by conducting black box testing on the application developed for the student final project guidance information system. This application uses the Iconix process-based SDLC (system development life cycle) model, covering student and lecturer profile information, guidance information, proposal submission, progress of the final thesis assignment, meeting schedule, guidance material, discussion forum, survey evaluation, and contact information. The SDLC model is employed in this research because it can effectively and efficiently achieve project targets, enhance software quality standards, and assist in better risk management and adaptation to change. The model comprises planning, needs analysis, design using the Iconix process, implementation, system testing, and maintenance. The Iconix process is utilized for system design modeling and analysis. Black box testing is performed on the system to verify that the system’s functional requirements are operating correctly. The findings of this research can serve as a control for management in the service and administration of final assignment guidance in higher education.

Interfacial microstructure and mechanical properties of CBN brazed in a continuous tunnel furnace with low-temperature Sn-Cu-Ti filler alloy

Currently, the most common process for manufacturing brazed cubic boron nitride (CBN) tools is vacuum brazing using Cu-based active filler alloys. However, the high brazing temperature of Cu-based alloys and the long heating time in a vacuum furnace inevitably cause severe thermal damage, thereby compromising the mechanical properties of the brazed CBN abrasives. In this study, CBN abrasives were brazed using low-temperature Sn-Cu-Ti filler alloys in a continuous tunnel furnace. The final contact angles of the Sn-Cu-Ti filler alloys on the surfaces of the brazed CBN abrasives were determined at 650 °C. When the Ti content in the alloy was 4 %, the final contact angle was 37.2° and the CBN maintained a good exposure height and achieved a firm holding force. The interfacial microstructure was analysed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). It was found that a layer of needle-like compounds, primarily comprising TiB2 and TiN, with an approximate thickness of 5 μm, was formed at the interface, indicating the formation of a chemical–metallurgical bond between the Sn-Cu-Ti alloy and CBN abrasive. The residual stresses and mechanical properties of brazed CBN abrasives with Sn-Cu-Ti and traditional Cu-based alloys were measured and compared. The results showed that compared to the brazed CBN with the Cu-based alloy, the average residual stress of the brazed CBN with the Sn-Cu-Ti alloy was reduced by 25.2 %, while the compressive strength and impact toughness increased by 25.3 % and 13.8 %, respectively. The experimental results provide new insights into reducing thermal damage to CBN for improving the processing performance of brazed CBN tools.

Study on wetting mechanism of Sn3Sc alloy on silica and sapphire surfaces

To further investigate the wetting mechanism of filler alloys containing active elements on oxide ceramics surfaces, we prepared a new filler alloy (Sn-3at.%Sc filler alloy) containing trace rare earth elements by vacuum melting furnace. Under high vacuum, its wetting behavior on silica and sapphire substrates was studied using a modified sessile drop method. The final contact angles of liquid Sn-3at.%Sc filler alloy on silica and sapphire surfaces are 6.0° and 9.8°, respectively, showing good wetting properties, and exhibiting similar wetting behavior at the same temperature. The same interfacial product Sc2O3 was detected at the interface of Sn-3at.%Sc/silica and Sn-3at.%Sc/sapphire systems. However, thermodynamic and spreading analysis suggests that Sc2O3 is precipitated in different ways at the interface of the two systems. The former is generated by an interfacial reaction, while the latter precipitates during the cooling process. The wettability of the Sn-3at.%Sc/silica system may depend on the interaction between the interface reaction products and residual scandium adsorption at the solid/liquid interface, while the wettability of Sn-3at.%Sc/sapphire system may depend on the adsorption of Sc-O clusters at the interface. These findings provide a theoretical basis and design ideas for further development of tin-based filler alloys and design of new type filler alloys.

Solid-liquid particle flow sealing mucus (PFSM) in enhancing coalbed methane (CBM) recovery: Multiple-perspectives analysis and mechanism insights

The paper presents an in-depth investigation of solid-liquid two-phase particle flow sealing mucus (PFSM) for enhanced coalbed methane (CBM) recovery. PFSM is composed of solid waste particles such as fly ash and rubber particles. The PFSM is assessed using multiple-perspectives analysis, which includes measurements of water retention, pressure expansion, rheological characteristics, adhesion, wettability, microscopy and field case studies. Single-factor and multi-factor studies are used to optimize slurry material ratios. The results show that PFSM has outstanding water retention characteristics, with over 80 % retention for 30 days at 30 °C, and impressive expansion performance, with 9.52 % at 0.6 MPa. The shear thinning curve conforms to the Cross model. After 30 s, the final contact angle is 75.17 °, which is about 6 ° smaller than that of cement based materials. Field experiments show that, after applying PFSM, the drainage gas concentration can be improved at least 60 % comparing to other sealing materials. This research findings could offer novel insights into enhancing CBM extraction, indicating potential for safer and more efficient coal mine production.

Pronounced modification of the wetting and spreading behavior of molten Ag-Cu alloy on TC4 substrate in response to high magnetic fields

This study investigated the wetting of TC4 substrate by molten Ag-Cu alloy under various high magnetic fields (HMFs) during the heating process. By examining changes in melt morphology, variations in contact angle, and characterizing the interface microstructure, we elucidated the underlying mechanism through which HMFs affected wetting behavior. The findings suggest that higher magnetic flux density resulted in smaller contact angles and more extensive spreading at the same temperature, culminating in a greater final spreading diameter. However, there was no significant difference in the final contact angle under various HMFs. Moreover, higher magnetic flux density resulted in a longer precursor zone and thicker reaction layer. The composition of precursor zones and reaction layers remained consistent with and without an HMF. The spreading process was divided into two stages regardless of the presence or absence of an HMF. In the absence of an HMF, the sluggish formation and spreading of precursor zone led to a lower spreading rate in the first spreading stage. Subsequently, as temperature rose, interface reactions drove rapid melt spreading, accelerating the spreading rate during the second spreading stage. In the presence of HMFs, the strong thermo-electromagnetic convection within melt and at liquid/solid interface notably promoted interface reactions and rapid formation of precursor zones, leading to a substantially heightened spreading rate in the first spreading stage. The slowing reaction rate and the limited volume of the melt collectively resulted in a slower spreading rate in the second spreading stage. This study provides new insights into modifying reactive wetting, with potential applications in advanced brazing techniques.

Effects of dental implant diameter and tapered body design on stress distribution in rigid polyurethane foam during insertion

Anchorage, evaluated by the maximum insertion torque (IT), refers to mechanical engagement between dental implant and host bone at the time of insertion without external loads. Sufficient anchorage has been highly recommended in the clinic. In several studies, the effects of implant diameter and taper body design under external loading have been evaluated after insertion; however, there are few studies, in which their effects on stress distribution during insertion have been investigated to understand establishment of anchorage. Therefore, the objective of this study was to investigate the effects of dental implant diameter and tapered body design on anchorage combining experiments, analytical modeling, and finite element analysis (FEA). Two implant designs (parallel-walled and tapered) with two implant diameters were inserted into rigid polyurethane (PU) foam with corresponding straight drill protocols. The IT was fit to the analytical model (R2 = 0.88–1.0). The insertion process was modeled using explicit FEA. For parallel-walled implants, normalized IT and final FEA contact ratio were not related to the implant diameter while the implant diameter affected normalized IT (R2 = 0.90, p < 0.05, β1 = 0.20 and β2 = 0.93, standardized regression coefficients for implant diameter and taper body design) and final FEA contact ratio of tapered implants. The taper design distributed the PU foam stress further away from the thread compared to parallel-walled implants, which demonstrated compression in PU foam established by the tapered body during insertion.

Robust and durable superlubricity enabled by carboxylated graphene quantum dots in lubricated steel contacts

Achieving macroscale superlubricity on engineering steel by utilizing aqueous green lubricants has gained growing interest, given its substantial potential to reduce energy consumption and carbon footprint. However, maintaining superlubricity under diverse sliding conditions over a prolonged duration is a major obstacle for real-scale applications. Herein, we report that a robust and durable tribofilm enabled by a unique lubrication mechanism based on carboxylated graphene quantum dots (CGQDs) in aqueous glycerol triggers macroscale superlubricity in self-mated steel contacts. A dedicated intermittent test was designed to show the superlubricity's robustness and the ability of the tribofilm to adapt to a variety of relevant sliding conditions. Moreover, the boundary film provides an average coefficient of friction of around 0.007 and up to 69 % wear reduction (compared to the base lubricant), resulting in the maintenance of superlubricity at a real final contact pressure of 123 MPa, which increases the upper limit of the contact pressure compared to current aqueous-lubricated steel contacts. The new superlubricity mechanism was enabled by the chemical adsorption of the CGQDs onto the worn metal surface, coupled with the tribo-induced structural degradation and transformation of the CGQDs into layered graphitic structures that generate an adaptable low-shear interface. This work provides new insights into the role of chemical adsorption and structural transformation of CGQDs in achieving superlubricity and is an important step forward for implementing energy-efficient and green lubrication technologies for industrial applications.

Experimental study on dynamic wetting behavior of liquid droplets on the aluminum surfaces excited by ultrasonic waves

In this paper, an anti-frosting strategy utilizing ultrasonic excitation to drive droplets away from cold surfaces was proposed. Based on this strategy, experimental studies were conducted to investigate the dynamic wetting behavior of droplets on aluminum surfaces under ultrasonic excitation. Specifically, the vibration characteristics of the plate and the properties of the droplets were revealed under the influence of ultrasonic waves. The results indicate that the droplet will undergo three stages of spreading-movement-contraction under ultrasonic excitation and the maximum contact angle hysteresis and maximum diameter spreading rate exhibit a positive correlation with droplet volume and ultrasonic power. It is also found that ultrasonic excitation can significantly reduce the droplet contact angle, which can be reduced by up to 70°. The contact angle hysteresis, diameter spreading rate and movement velocity show almost the same trend with time under ultrasonic action, that is, increasing first and then decreasing. Notably, the contact angle hysteresis and the diameter spreading rate reached a peak later than the movement velocity, which is attributed to the droplet's deformation relies on the full propagation of the ultrasonic vibration inside the droplet, resulting in hysteresis. Finally, it is found that the droplet-wetting state is permanently changed under ultrasonic action and the final contact angle is greatly reduced compared to the initial value even after stopping ultrasonic excitation.

Application of artificial neural networks and Langmuir and Freundlich isotherm models to the removal of textile dye using biosorbents: A comparative study among methodologies

AbstractAdsorption isotherms are valuable tools for describing the interaction between adsorbate and adsorbent since they demonstrate the equilibrium relationship. The Langmuir and Freundlich models are the most commonly used isotherm models to describe these relationships; still, they cannot consistently deliver efficient results due to the assumptions of the model not predicting more complex situations as occurs in biosorption. Artificial neural networks (ANN) are a set of algorithms modelled loosely after the human brain and are designed to recognize patterns. The ANN tool can overcome problems isotherm models have in describing the interactions mentioned and help define the best conditions for a given adsorption process. This paper reports the application of ANNs for predicting the removal efficiency of textile dye Neolan Black WA (Acid Black 52) using orange peel and sugarcane bagasse as biosorbents. The Freundlich, Langmuir, pseudo‐first‐order, and pseudo‐second‐order models were applied and compared to the ANN model. The parameters evaluated were initial dye concentration (10–600 mg/L), final dye concentration (0–83.44 mg/L), biosorbent mass (1.5 g), pH (2), and contact time of dye (0.167–24 h). Two classes of ANNs, Elman and feed‐forward networks, were tested with a mean square error of 0.0212 and 0.7274 for the isotherm and kinetics, respectively. Compared to the conventional isotherm and kinetic models, the Elman network predicted the amount adsorbed by the biosorbents with higher precision, acquiring a determination coefficient of 0.9998 and a mean square error of 8.75 × 10−5.

Wettability Characteristics of Nanoporous Carbon Bricks Incorporated with Al2O3 Phase and Molten Iron in Sustainable and Low‐Carbon Blast Furnace

Analyzing the wetting behavior between carbon brick and molten iron in a blast furnace is crucial for understanding prolonging the furnace's lifespan. This study investigates the wetting behavior between microporous carbon brick and molten iron. The contact angle between the carbon brick and molten iron is measured at various temperatures and carbon saturation conditions, while the microscopic morphology of the reacted interface is examined. Furthermore, the wetting mechanism of molten iron on the carbon brick surface is elucidated. The findings reveal that both the microporous carbon brick and molten iron remain in a never‐wetting state within the furnace. As the temperature rises from 1150 to 1450 °C, the contact angle decreases from 138° to 128°, whereas the initial carbon content in the molten iron increases from 2.6 wt% to 4.1 wt%. Additionally, the initial contact angles gradually increase from 128.3° to 133.6°, with final equilibrium contact angles of 119.2° to 127.0°, indicating a nonwetting state. The carbon dissolution reaction occurs within the carbon matrix region of the microporous carbon brick prior to carbon saturation in the molten iron. Conversely, the presence of a ceramic phase in the ceramic area hampers both chemical erosion and physical penetration of the molten iron.

Effects of Sulfate Ions on Crude Oil Adsorption/Desorption on Carbonate Rocks: Experimental and Molecular Simulations.

In the background of the strong oil wettability and low production by water flooding in carbonate reservoirs, low-salinity water containing sulfate ions can significantly change the surface wettability of carbonate rocks and thus increase the sweeping area; however, the absorption and desorption mechanisms of the oil film in the carbonate rock surface remain unclear. This paper analyzed the wettability alternation of carbonate rocks' surface in pure water and sodium sulfate solution. At the same time, MD (Materials Studio) software was used to simulate the formation process of the oil film and the effect of sulfate ions on the desorption of the oil film on the surface of carbonate rocks. The experimental results showed that sodium sulfate solution could accelerate the rate from oil-wet to water-wet and the final contact angle (49°) was smaller than that in pure water. The simulation results showed that dodecane molecules moved to the surface of calcite to form a double layer of the oil film and that the oil film near the calcite surface had a high-density stable structure under the van der Waals and electrostatic action. The hydrating sulfate ions above the oil film broke through the double oil film to form a water channel mainly under the action of electrostatic force and a hydrogen bond and then adsorbed on the calcite surface. A large number of water molecules moved down the water channel based on a strong hydrogen bonding force and crowded out the oil molecules on the surface of the calcite, resulting in the oil film detachment. This work aims to explain the interaction of oil molecules, water molecules, and SO42- ions at the molecular scale and guide the practical application of low-salinity water flooding in carbonate reservoirs.

Differences in run-up, take-off, and flight characteristics: successful vs. unsuccessful high jump attempts at the IAAF world championships.

Studies previously conducted on high jump have yielded important information regarding successful performance. However, analyses in competitive scenarios have often disregarded athletes' unsuccessful attempts. This study aimed to investigate the biomechanical differences between successful and unsuccessful jumps during competition. High-speed video footage (200 Hz) was obtained from 11 athletes during the 2018 Men's World Athletics Indoor Championship Final. From each athlete, one successful (SU) and one unsuccessful (UN) jump at the same bar height were included in the analysis, leaving seven athletes in total. Following whole-body 3D manual digitization, several temporal and kinematic variables were calculated for the run-up, take-off, and flight phases of each jump. During SU jumps, athletes raised the center of mass to a greater extent (p < 0.01) from take-off. Touchdown in SU jumps was characterized by a faster anteroposterior velocity (p < 0.05), lower backward lean (p < 0.05), and changes in joint angles for the stance and trail limbs (p < 0.05). Athletes also shortened the final contact time during SU jumps (p < 0.01) after producing a longer flight time in the final step of the run-up (p < 0.05). Elite-level high jumpers undertake a series of adjustments to successfully clear the bar after UN jumps. These adjustments reinforce the importance of the run-up in setting the foundations for take-off and bar clearance. Furthermore, the findings demonstrate the need for coaches to be mindful of the adjustments required in stance and trail limbs when looking to optimize feedback to athletes during training and competition.

Anti-bacterial films developed by incorporating shikonin extracted from radix lithospermi and nano-ZnO into chitosan/polyvinyl alcohol for visual monitoring of shrimp freshness

In recent years, the utilization of smart colorimetric packaging films for monitoring food freshness has garnered significant concentration. However, their limited tensile strength, hydrophobicity, antioxidant, and antibacterial properties have been substantial barriers to widespread adoption. In this study, we harnessed the potential of biodegradable materials, specifically chitosan/polyvinyl alcohol, alongside shikonin extracted from Radix Lithospermi and ZnO nanoparticles, to create a novel colorimetric sensing film. This film boasts an impressive tensile strength of 82.36 ± 2.13 MPa, enhanced hydrophobic characteristics (exemplified by a final contact angle of 99.81°), and outstanding antioxidant and antibacterial properties. It is designed for real-time monitoring of shrimp freshness. Additionally, we verified the effectiveness of this sensing film in detecting shrimp freshness across varying temperature conditions, namely 25 °C and 4 °C was validated through the measurement of total volatile basic nitrogen (TVB-N). Visual inspection unequivocally revealed a transition in color from dark red to purple-light blue and finally to dark bluish providing a clear indication of shrimp spoilage, which demonstrated a strong correlation with the TVB-N content in shrimp measured through standard laboratory procedures. The colorimetric sensing film developed in this study holds great promise for creating smart labels with exceptional antioxidant and antibacterial properties, tailored for visual freshness monitoring of shrimp.

Wettability, reactivity, and interface structure in Mg/Ni system

The sessile drop method was applied to the experimental investigation of the wetting and spreading behaviors of liquid Mg drops on pure Ni substrates. For comparison, the experiments were performed in two variants: (1) using the Capillary Purification (CP) procedure, which allows the non-contact heating and squeezing of a pure oxide-free Mg drop; (2) by classical Contact Heating (CH) procedure. The high-temperature tests were performed under isothermal conditions (CP: 760 °C for 30 s; CH: 715 °C for 300 s) using Ar + 5 wt% H2 atmosphere. During the sessile drop tests, images of the Mg/Ni couples were recorded by CCD cameras (57 fps), which were then applied to calculate the contact angles of metal/substrate couples. Scanning and transmission electron microscopy analyses, both coupled with energy-dispersive X-ray spectroscopy, were used for detailed structural characterization of the solidified couples.It was found that an oxide-free Mg drop obtained by the CP procedure showed a wetting phenomenon on the Ni substrate (an average contact angle θ < 90° in < 1 s), followed by fast spreading and good wetting over the Ni substrate (θ(CP) ∼ 20° in 5 s) to form a final contact angle of θf(CP) ∼ 18°. In contrast, a different wetting behavior was observed for the CH procedure, where the unavoidable primary oxide film on the Mg surface blocked the spreading of liquid Mg showing apparently non-wetting behavior after 300 s contact at the test temperature.However, in both cases, the deep craters formed in the Ni substrates under the Mg drops and significant change in the structure of initially pure Mg drops to Mg-Ni alloys suggest a strong dissolution of Ni in liquid Mg and apparent values of the final contact angles measured for the Mg/Ni system.

An analytical framework for predicting the total freezing delay time of water droplet impact on hydrophobic solid surfaces

An analytical framework is developed to investigate the impact and freezing delay of a water droplet on solid surfaces, particularly hydrophobic ones, at subfreezing temperatures. Submodules for droplet dynamics, supercooling, nucleation and recalescence, and equilibrium solidification are developed for different droplet impact and freezing stages. These submodules are then integrated to estimate the total freezing delay time per unit mass of the water droplet. It is found that the nucleation time depends on the impact height, surface temperature, droplet impact temperature, and the droplet-substrate contact angle, while the solidification time depends on the droplet size, the nucleation temperature, and the droplet final contact diameter, which is related to the initial droplet diameter, the Weber number, the Reynolds number, and contact angle. The analytical model is validated with results from droplet freezing experiments in a subfreezing environment. By simplifying the complex droplet dynamics, nucleation, and freezing processes, the new analytical framework provides a useful way to estimate the total freezing time of impacting water droplets on hydrophobic surfaces. Its accuracy needs to be improved for practical engineering applications.

Between-day reliability of inertial measurement unit parameters during soccer-specific change of direction test

This study assessed the between-day reliability of change of direction (COD) biomechanics and speed in youth soccer players using inertial measurement units (IMUs) and high-speed video. A soccer-specific COD test including a 180° pivot turn was performed in both directions by 15 elite female (age: 15.3 ± 0.6 years; height 162.6 ± 5.5 cm; body mass: 56.7 ± 7.1 kg) and 22 elite male (age: 15.4 ± 0.5 years; height 169 ± 5.9 cm; body mass: 58.5 ± 8.5 kg) youth soccer players in two consecutive days. The reliability of the variables was quantified by using intra-class correlation coefficient (ICC) analysis with limits of agreement (LoA) and Bland–Altman plots. Based on the results, neither peak resultant acceleration (PRA) nor peak angular velocity (PAV) during final foot contact was sufficiently reliable for 180° pivot turn biomechanics (poor reliability, &lt; 0.5), but the reliability of players’ running time to turn and total time was between acceptable to good (0.9&gt;; &gt; 0.7). However, when analyzing females and males separately, the PRA and angular velocity ICC's for females had poor to acceptable reliability, when turning left, and were statistically different from males ( Z-score &gt; 1.96). Acceptable to good reliability with reasonable (max 15% difference) LoA implies that speed measures in different phases of COD could reliably reproduce individual differences in 180° pivot turn COD speed. Sex-related differences in repeatability of acceleration and angular velocity call for more comprehensive research in the future. PAV and PRA would not be recommended for the purpose of analyzing individual repeatability of specific steps of COD movement.

Microbiological contamination of the inner surface of finished water filling taps at bottled drinking water producers in Khanh Hoa province

The finished water filling tap is the final contact point of filtered drinking water before&amp;nbsp;bottling. Therefore, microbial contamination at this site may result in cross-contamination&amp;nbsp;into the finished water in the bottle. This study was conducted to evaluate microbiological&amp;nbsp;contamination on the inner surface of the finished water filling tap at the bottled drinking&amp;nbsp;water producers in Khanh Hoa in 2022. A total of 93 swab samples of the inside surface of&amp;nbsp;the tap at 93 producers were subjected to a test for ATP (Adenosine Triphosphate), total&amp;nbsp;plate count (TPC), coliform, Escherichia coli, Pseudomonas aeruginosa, Streptococci&amp;nbsp;feacal, and Clostridia. There were 72/93 (77.4%) samples with ATP values higher than 300&amp;nbsp;RLU/cm2. The geometric mean of ATP and TPC were 3.1&amp;plusmn;0.8 log (RLU/cm2) and 3.5&amp;plusmn;1.2&amp;nbsp;log (CFU/cm2), respectively. The ATP and TPC were linear correlated, indicating that the&amp;nbsp;surface ATP value inside the finished water filling tap was mainly formed by&amp;nbsp;microorganisms. In addition, 6/93 (6.5%) samples were found to be positive for coliform,&amp;nbsp;including 3 strains of Enterobacter cloacae, 2 strains of Klebsiella pneumoniae and 1 strain&amp;nbsp;of Enterobacter aerogenes. Moreover, 1/93 (1.1%) samples were infected with P.&amp;nbsp;aeruginosa. All 7 strains of these bacteria were biofilm producers under laboratory&amp;nbsp;conditions. Our results demonstrated that the cleaning and decontamination of finished water&amp;nbsp;filling taps were not properly processed, thereby increasing the risk of microbial&amp;nbsp;contamination into finished bottled water.