Pad Material Research Articles

Psychological, Informational, and Material Factors Impacting Girls’ Menstruation-related School Absenteeism in Rural Tanzania

Girls’ education remains a significant challenge in sub-Saharan Africa as it is estimated that 1 in 10 adolescent girls miss school during their menstrual cycle. In Tanzania, girls must attend school regularly to be sufficiently prepared for the National Examinations that serve as gatekeepers to higher education levels and advanced careers. Our current study focuses on contextual factors that limit Tanzanian girls’ school attendance during menstruation (ADM). Using descriptive and inferential statistical techniques and survey data from post-menarche adolescent girls (N = 610) in the Mara region of Tanzania, the findings revealed that psychological, physiological, informational, and material factors increase the likelihood of girls’ school absenteeism during menstruation. The results from this study indicate that generalized anxiety, depression, worry about menstruation, menstruation preparation, and menstrual pad material have a direct impact on ADM. The findings from this study have implications for educational policy and school leadership

Comparative tribological study of the material intended for a lightweight HAMNC brake rotor sliding against NAO brake pad material

Abstract The present work studies the lightweight Hybrid Aluminium Metal Matrix Nanocomposite (HAMNC) for brake rotor application. The novel HAMNC brake rotor material is fabricated by reinforcing 1 wt. % nano Boron carbide (nB4C) and 0.75 wt.% nano Titanium dioxide (nTiO2) employing ultrasonic-squeeze-assisted stir-casting process. The developed HAMNC and a commercial Gray Cast Iron (GCI) brake rotor material was subjected to density, hardness, thermal, corrosion, and tribological studies. The results indicated that the HAMNC brake rotor material is 60% lighter and extremely corrosive resistant compared with GCI material. Also, the dry sliding wear study done using Non Asbestos Organic (NAO) commercial brake pad as the pin material exhibited that the HAMNC brake rotor material possessed a higher wear-resistant behavior compared to GCI.

Design Issues and Solutions for Improving the Comfort of Neo-Ming Style Chair

This paper explores the design issues and solutions for improving the comfort of new Ming-style chairs. It first analyzes the historical origins, traditional aesthetics, and modern users' new demands for comfort in these chairs. Then, it highlights the comfort-related challenges in terms of chair form, materials, structure, and usage scenarios. The study proposes design principles from the perspectives of ergonomics, material innovation, structural optimization, and modern usage scenarios. Specific strategies to enhance comfort are provided, such as optimizing the angle between the chair back and chair surface, improving cushion materials, optimizing the chair's supporting structure, and incorporating intelligent design. This paper also discusses the challenges of integrating technology with traditional design, the application of eco-friendly materials, and the diverse demands of consumer groups. Finally, it summarizes the future trends and challenges in the comfort-focused design of Neo-Ming style chair.

Effects of straws on greenhouse gas emissions in the ectopic fermentation system

Straws are commonly used padding materials in the ectopic fermentation system, but their effects on greenhouse gas emissions are not well understood. This study compared the effects of rape, rice and corn straws on the fermentation performance of the ectopic fermentation system. Compared with corn straw, the treatment groups with rape straw and rice straw significantly increased the alpha diversity of the fermentation system, and simultaneously mitigated the cumulative emissions of CO2 and N2O by up to 32.4% and 93.9%, respectively. The CO2 and N2O peak emission in the treatment group with corn straw reached 1.4 × 106 and 36.2 mg/m2/d, respectively. CH4 peak emission was one order of magnitude lower than that of N2O in the ectopic fermentation system. Redundancy analysis showed that Pseudoxanthomonas sp000510725 was the key specie that positively affect the fermentation temperature, CO2 and N2O emissions in the fermentation system. Nitrogen metabolism genes, such as nosZ, nirK, and nirS were more abundant in the surface layer of the fermentation system, indicating more active nitrogen metabolism in this region, and the core zone could be the primary source of N2O emissions. Those findings indicated that rape and rice straw can be potential padding materials for mitigating greenhouse gas emissions in large-scale ectopic fermentation system.

Enhanced material removal modeling in cylindrical bonnet tool polishing: Incorporating time-dependent pad wear effects

To enhance the accuracy and stability of the material removal model for cylindrical bonnet tool polishing (CBTP), this study introduces a model incorporating the time-varying wear effect of the polishing pad. Initially, the functional principles of the CBTP method are systematically outlined. An advanced material removal model is then proposed, which accounts for the impact of pad wear on pressure and velocity distributions within the contact area. Experimental methods were employed to explore how pad wear affects the pad surface morphology, polishing quality, and material removal rates. Findings reveal that pad wear considerably influences both the depth of material removal and the quality of the polished surface. Validation experiments demonstrate that the enhanced model is accurate and stable. Including the time-varying factor, the discrepancy between the predicted and experimental values of the polishing spot size was 9.29 %, while the accuracy of the predicted material removal depth reached 90.74 %. Additionally, the removal profiles generated by the improved model closely matched those observed experimentally.

Experimental study of rotational friction damper for seismic response control: friction material comparison and configuration optimization

Rotational friction dampers (RFDs) can be incorporated into structures flexibly as energy-dissipation devices for seismic response control. However, the basic primary form of RFD has three main challenges and objectives in enhancing its performance: (1) avoiding strength fluctuation and jittering, namely, improving the stability of the performance, (2) enhancing the strength, and (3) relieving the basic assumption that the clamping pressure is uniformly distributed on the friction pads and ensuring the accuracy of the theoretical equation. To address these issues, this study proposes four potential approaches: (1) selecting a friction material with a stable performance, (2) increasing the friction coefficient, (3) increasing the clamping force, and (4) optimizing key configurations. Based on these concepts, two sets of experimental studies, including 27 friction pad material comparison tests and 17 lug plate and clamping bolt configuration optimization tests, were conducted. According to the test results, the fiber-reinforced resin-based composite (FRRC) material was found to be better than H62 brass and 7075 aluminum alloy in realizing a high friction coefficient and stable performance, as well as achieving uniformly distributed pressure. The four-bolt lug plate and six-bolt lug plate with stiffening ribs were found to be effective in realizing a high clamping force and, thus, a high RFD strength, as well as in achieving a uniformly distributed pressure. In contrast, the single-bolt lug plate could not realize a high clamping force because of the tightening torque limit. A six-bolt lug plate can cause pressure concentration and edge damage to the friction pad.

Research on the Application of Cushion and Isolation Materials in Protecting the over Shield Tunnel

The portal frame, as an innovative subway protection structure, primarily serves the development of underground spaces above shield tunneling for subways. It comprises foundation piles along both sides of the tunnel and a transition thick plate. When the transfer thick plate sustains loads at its midspan, deformation occurs, interacting with the underlying soil to generate additional stresses, thereby potentially impacting the subway tunnel beneath negatively. This study, anchored in the real-case scenario of Qianhai Exchange Square, employs finite element analysis to investigate the interaction mechanisms between the transfer thick plate under midspan loading and soils of varying properties. Findings revealed a characteristic distribution pattern of additional stresses in the soil—smaller at the edges and larger at the center. Furthermore, under equal loading conditions, there's a positive correlation between soil stiffness and induced additional stress, while an inverse relationship exists with the vertical deformation of the transfer thick plate. In response to this issue, the paper innovatively proposes embedding a cushioning and isolation layer under the transfer thick plate. Based on the results of full-scale tunnel tests carried out during the early stages of the project, and by employing high-precision finite element simulations, the bearing capacity of the tunnel was determined. This analysis, in turn, informed the formulation of selection principles for the cushioning and isolation materials in a feedback manner. Computational verifications showed that appropriately designing the cushioning and isolation layer can significantly reduce additional stresses in the foundation soil, thereby effectively alleviating the impact of concentrated upper loads on the shield tunnel.

On the Use of Pad Mechanical Properties as a Proxy for Conditioning Response

A proliferation of pad materials in recent years, coupled with the increasing complexity of process integration and limited resources available for process development, has highlighted the need for a more in depth understanding of conditioning interactions and better predictive tools for process and consumable design. We have previously noted a range of conditioning response as illustrated in Figure 1. As the figure illustrates, on some materials the surface height distribution imparted by the pad conditioner is shifted to the left relative to the exponential signature of the pad native porosity which is used as a reference. Denoted regime 1, these surfaces are characterized by the prevalence of “eyelid” features which obscure the line-of-sight path to the bottoms of the pores. In regime 2, the surface height distribution is more balanced, with a smooth transition between the exponential porosity signature and the conditioning signature. In regime 3, there is an abrupt disconnect between the exponential porosity signature and the conditioner signature. Such surfaces are characterized by deep gouges.We are investigating pad material tensile properties as a proxy to help understand and predict these conditioning responses. Figure 2 illustrates the range of typical tensile behavior for polymers. While Figure 2 invokes temperature as the variable that drives these behaviors, note that strain rate can also drive tensile behavior across this range with high temperature being analogous to low strain rate and vice versa.Figure 3 and Table 1 summarize some results from our testing of IC1000, VP5000, VP6000, IK4250H and IK4350L. We have determined that grooved pad materials at their nominal dimensions are adequate for testing according to ASTM D638: Standard Test Method for Tensile Properties of Plastics. Typical delivered pad thickness is within the specifications for sample thickness, and as long as the grooves are oriented to be substantially parallel with the strain axis (pulling direction) reproducible results can be obtained. A range of properties spanning at least about 2x is observed in these pads.Figure 4 gives one example of how this information can be directly applied. The figure illustrates a manifestation of the threshold behavior that is typically observed when conditioning with a pad conditioner with uniform tip height, where all the cutting points are controlled within a height range of about 10 µm. As opposed to a conventional conditioning platform, where there is a much wider range of tip heights, the uniform height-controlled conditioner exhibits a threshold behavior where no measurable cutting occurs below a limiting condition down-force (cdf). Figure 4 illustrates the disconnect between a high down-force, accelerated cutting test, using 14 lbs cdf and designed to return the “CR” value for a conditioner, and typical process cdf levels, in the range of 5 lbs cdf. Note that CR values are generally about an order of magnitude higher than comparable polishing tool level pad wear rates. Whereas conventional platforms yield a linear response between CR and tool level pad wear rates, the uniform height design exhibits an offset, such that at low CR levels, low pad wear rates are observed. The position of this threshold is a function of pad type. These data suggest that this threshold can be correlated with the mechanical strength of the pad material, as determined by the tensile test results.We have also explored the effect of strain rate on tensile response. Strain rates in a typical CMP process may be as high as 105 s-1, and as shown in Figure 2, strain rate can have a significant effect on material behavior. Figure 5 illustrates typical results, illustrating the extremes of response for this group of pads, and Figure 6 shows the normalized response of offset yield and tensile strength as a function of strain rate. Of these materials, only IK4350L exhibits a divergent response, and as shown in Figure 7, IK4350L typically exhibits the most abrupt transition between the exponential porosity signature and the conditioner cutting signature, indicating a tendency towards the gross over-conditioning behavior characteristic of regime 3.Over the range of strain rates explored here, all of these materials can be characterized as “rubbery”. This rubbery behavior can be understood in the context of reported property measurements of CMP pads, which indicate distinct glass transitions related to the soft and hard phases of the polyurethane from which the pad is made. This analysis suggests that pad behavior is dominated by the “rubbery plateau” of the soft segment of the polymer, with the glass transition of the hard segment occurring above typical polishing temperatures. Figure 1

Evolving Preston’s Equation in Chemical Mechanical Planarization

The evolution of semiconductor devices necessitates greater control parameters for enhancing CMP process controllability. Historically, CMP engineers have sought to improve polishing process performance by real-time control of time, pressure, and velocity using Preston’s equation. However, Preston’s equation has traditionally addressed blanket-wafer or non-patterned wafer’s vertical or horizontal scale controllability, such as wafer center to edge or the in-wafer non-uniformity expressed by percentage. However, limited control variables cannot determine patterning profile changes.Upon closer examination of the basic Preston’s equation, other factors were considered constant or environmental parameters, excluding pressure and velocity. Current and future scaled-down devices demand additional control parameters to achieve nanometer-scale vertical controllability with patterned wafers. This presentation introduces an extended Preston’s equation by incorporating more control parameters, including temperature and slurry concentration. The study reveals that lowering and controlling the polishing temperature induces slurry selectivity changes by modulating the activation energy between the slurry and wafer. This temperature control also drives pad material changes that impact selectivity. Furthermore, the study evaluates in-situ slurry composition control to assess its real-time impact on wafer performance. When all five active parameters are combined into the extended Preston’s equation, it is demonstrated that real-time nanometer vertical scaling is achievable. The results of this study provide insights into the future design direction of CMP equipment, which will be communicated in this talk along with the concept of future CMP equipment.

Research on friction and wear properties of new energy micro logistics vans brake materials under different ambient temperature and humidity conditions

This study explores the friction and wear performance of brake materials for new energy micro logistics vans under different ambient temperature (3 °C, 23 °C, 43 °C) and humidity conditions (35 %, 65 %, 95 %) using pin-disc experimental device. The findings reveal that at 3 °C, the friction coefficient exhibits extreme sensitivity to changes in humidity, with a significant reduction as humidity increases. Simultaneously, the increase of humidity leads to the transition from adhesive wear to abrasive wear and fatigue wear. At room temperature (23 °C) and 43 °C, humidity has minimal impact on the friction coefficient; however, higher humidity promotes oxidation film formation on the friction surface leading to dominant oxidation wear. Notably, in low-humidity environments, temperatures at 3 °C and 43 °C cause severe brake pad wear. The severity is greater at 43 °C because the resin-based components within the brake pad material decompose at elevated temperatures. Under such circumstances, appropriately increased humidity helps mitigate brake pad wear rates. However, too much humidity can increase fatigue wear of brake pad materials.

Acoustic noise reduction in the NexGen 7 T scanner.

Driven by the Lorentz force, acoustic noise may arguably be the next physiological challenge associated with ultra-high field MRI scanners and powerful gradient coils. This work consisted of isolating and mitigating the main sound pathway in the NexGen 7 T scanner equipped with the investigational Impulse head gradient coil. Sound pressure level (SPL) measurements were performed with and without the RF coil to assess its acoustic impact. Vibration measurements were carried out on the gradient coil, the RF coil, and on the patient table to distinguish the different vibration mechanisms and pathways. Vibrations of the RF coil were modified by either making contact with the patient bore liner with padding material or by changing directly the RF shield with phosphor bronze mesh material. SPL and vibration measurements demonstrated that eddy-currents induced in the RF shield were the primary cause of acoustic noise. Replacing the conventional solid copper shield with phosphor bronze mesh material altered the vibrations of the RF shield and decreased SPL by 6 to 8 dB at the highest frequencies in EPI, depending on the gradient axis, while boosting the transmit B1 + field by 15%. Padding led to slightly less sound reduction on the X and Z gradient axes, but with minimal impact for the Y axis. This study demonstrates the potential importance of eddy-current induced vibrations in the RF coil in terms of acoustic noise and opens new horizons for mitigation measures.

Dynamic response of rock sheds to successive rockfall impacts using lightweight expanded clay aggregate (LECA) cushions: An experimental and numerical study

This study investigates the effectiveness of Lightweight Expanded Clay Aggregate (LECA) as a novel cushion material mitigating repeated rockfall impacts on reinforced concrete (RC) slabs in rock sheds. Small-scale impact tests and finite element simulations analyze LECA particle size, cushioning material, block shape, and impact energy level influence on the dynamic response and damage. Results show LECA outperforms sand in attenuating impact forces and transmitted loads under successive impacts, which indicates a better protection effect on the substructure. Smaller LECA particles lead to wider stress distribution angles, longer impact durations, and lower peak forces. Block shape significantly influences impact force, with higher unified nose factors increasing forces. LECA cushions exhibit a dynamic amplification factor less than 1, indicating reduced transmitted loads compared to sand. Under high-impact energy conditions, the LECA cushion limits RC slab deflection within the elastic limit across all block shapes, while sand exceeds the elastic limit, potentially leading to structural failure. LECA mitigates flexural cracking and redistributes loads more uniformly, reducing overall RC slab damage compared to sand. However, localized failure modes require further optimization. This study highlights LECA's potential for enhancing rock shed structural safety and resilience against severe rockfall events, providing insights for optimal mitigation strategies.

Development and Process Integration of an Alternative Demoulding System for High-Pressure Die Casting Using a Contoured Vacuum Mask

This study presents the development and process integration of an alternative demoulding system for high-pressure die casting. The system is aimed at the removal of large structural castings, which are becoming increasingly popular in the industry under the terms mega- and gigacasting. The development differs from conventional systems in the fact that it completely avoids ejectors and realises the demoulding via the principle of vacuum suction cups. Preliminary tests were carried out in which various established materials for vacuum cups were initially identified and the suitability of the selected cup concept was investigated by varying influencing variables from the high-pressure die casting. These tests showed that a suction pad material combination of an elastomer with a thermal barrier and an aramid felt on the surface provides the best results under the given process boundary conditions. Based on this, a multi-segmented vacuum mask with contour adaptation to the casting to be removed was developed. This vacuum mask is used to build up the holding force between the casting and the removal device. The necessary removal force is applied via pneumatic cylinders. The functional capability of the concept and the system integration was verified by experiments on a real die-casting mould for test specimens. The shrinkage and demoulding process can be successfully modelled in the simulation and the real measured demoulding force is only approx. 15% higher than in the simulation. During demoulding in the high-pressure die-casting process, vacuums of up to 88.7% were achieved at temperatures up to 395 °C.

Determination of Performance of Different Pad Materials and Energy Consumption Values of Direct Evaporative Cooler

The purpose of this study is to determine the performances of luffa and greenhouse shading netting (which can be used as alternatives to commercial cellulose pads, that are popular for cooling greenhouses), the contribution of external shading to the evaporative cooling performance, and the energy consumption of the direct evaporative cooler. In this experiment, eight different applications were evaluated: natural ventilation (NV), natural ventilation combined with external shading net (NV + ESN), cellulose pad (CP), cellulose pad combined with external shading net (CP + ESN), luffa pad (LP), luffa pad combined with external shading net (LP + ESN), shading net pad (SNP), and shading net pad combined with external shading net (SNP + ESN). The cooling efficiencies of CP, CP + ESN, LP, LP + ESN, SNP, and SNP + ESN were found to be 37.6%, 45.0%, 38.9%, 41.2%, 24.4%, 29.1%, respectively. Moreover, their cooling capacities were 2.6 kW, 3.0 kW, 2.8 kW, 3.0 kW, 1.7 kW, 2.0 kW, respectively. The system water consumption values were 2.9, 3.1, 2.8, 3.2, 2.4, 2.4 l h−1, respectively. The performance coefficients of the system were determined to be 10.2, 12.1, 11.3, 11.9, 6.6, 7.8. The system’s electricity consumption per unit area was 0.15 kWh m−2. As a result of the study, it was determined that commercially used cellulose pads have advantages over luffa and shading net materials. However, luffa pads can be a good alternative to cellulose pads, considering their local availability, initial cost, cooling efficiency, and capacity.

Striking Differences in Kendo Headgear.

Kendo, a martial art developed by the samurai, is rooted deep in Japanese culture with traditional armor that has seen little change over the past centuries.Despite its century-old design, kendo helmets are manufactured without third-party testing to verify their quality and effectiveness against head trauma. To evaluate the effectiveness of different helmet stitching patterns and padding materials in mitigating impact forces that could lead to sports-related concussions (SRC) in kendo, and to assess variations in safety performance across different genders and kendo ranks (Dan and Kyu). We collected data from 10 kendo practitioners (six males and four females), analyzing over 4,000 strikes using shinai on a sensor-equipped mannequin. Various helmet stitching patterns (ranging from 2 mm to 9 mm) and padding types (polyurethane-based and different thicknesses of cotton-based pads) were tested under controlled conditions simulating realistic impacts encountered in kendo practice. The results indicated that helmets with wider stitching patterns (e.g. 8 mm and 9 mm) generally offered better energy absorption, exhibiting statistically significant lower mean g-forces with a 95% confidence interval compared to tighter patterns (2 mm, 4 mm, 6 mm, and 8 mm x 2 mm) (p < 0.001). Additionally, the polyurethane-based padding outperformed cotton-based padding by a statistically significant reduction of impact force (p < 0.001). Significant differences in striking force were also observed between genders and ranks, with male and higher-rank (Dan) practitioners delivering stronger impacts (both p < 0.001). This study highlights the critical influence of helmet stitching patterns and padding materials on the protective capabilities against concussions in kendo. Even though helmets with narrower stitching patterns cost more, helmets with wider stitching patterns and polyurethane padding material provide enhanced safety benefits. We do not know how the difference in striking force between genders and ranks affects the outcome of a kendo match.

Mechanically robust poly(urethane-imide) aerogels with excellent thermal insulation and sound absorption by ambient drying

Polyimide (PI) aerogels are the great candidates for sound absorption, thermal insulation and mechanical cushioning materials due to their low density, excellent mechanical properties and good thermal stability. However, the high shrinkage and hydrophilicity of PI aerogels, as well as the time-consuming and complexity of the process directly limit their wide application in many fields. Herein, a facile one-step method for the synthesis of porous monolithic poly(urethane-imide) (PUI) aerogels was successfully developed. Hydrothermal synthesis and ambient drying methods were adopted in the construction of monolithic chemically cross-linked PUI aerogels, which avoids the complex imidization process. PUI aerogels were homogeneously produced by a chemical cross-linking copolymerization reaction between polyurethane (PU) oligomers, Benzene-1,2,4,5-tetracarboxylic dianhydride (PMDA) and 1, 3, 5-tris (6-isocyanatohexyl)-1, 3, 5-triazine-2, 4, 6(1H, 3H, 5H)-trione without any catalysts. Interestingly, the introduction of linear flexible PU oligomers chain segments effectively prevented the shrinkage of the network backbone and enhanced the hydrophobicity of PUI aerogels. The obtained PUI aerogels have low density (0.196 g/cm3), low shrinkage (9.30%), high porosity (79.54%) and hydrophobicity (water contact angle of 129.2°). Under high pressure, PUI aerogel was compressed but not break and the compression Young's modulus as high as 3.638 MPa. Moreover, the thermal conductivity of PUI aerogels was only 59.92 mW/m/K at 150 °C. When the back cavity depth was 5 mm, the highest sound absorption coefficient of PUI aerogel was up to 0.7219. This work provides a new method for the development of lightweight, high-mechanical-strength polymer aerogels, and the prepared aerogels have a potential application in the field of multifunctional integrated sound absorption materials.

Development of functionally gradient Cu-Fe based sintered brake pad materials

The world is seeking a sustainable co-existence with nature to preserve the balance of our ecosystem. This has opened a wider market for green and renewable forms of energy to realize the energy requirements of global countries. Among the various renewable energy sources, harnessing the kinetic energy of the wind through a turbine to generate electricity has seen an ardent growth. Wind turbines, in general, function between 2 m s−1 and 25 m s−1 wind speed. When the winds cross the cut-out speed (25 m s−1) or during the maintenance of wind turbine components, the brakes are implemented. The primary aerodynamic and secondary mechanical brakes comprise the wind turbine braking system. The mechanical brake pads are fixed to the brake caliper. On braking, the brake caliper pushes the brake pads against the brake disc. This recurring action gradually wears the brake material. The presence of ceramic particles in the traditionally used bulk composite pads imparts poor joint properties between the brake pad and caliper. These mandate frequent replacement of the brake pads. The current research work developed a functionally gradient brake pad through the powder metallurgy technique. The microstructure, microhardness, and tribological properties of the fabricated brake pads are tested and analyzed. Microstructural analysis revealed a homogeneous distribution of the reinforcements in the metal matrix. COF was observed to be within the desired range of between 0.3 and 0.4. The brake pad exhibited a combination of adhesive-abrasive-oxidative wear.

Current Advances and Gaps in Knowledge on Personalizing Masks for Noninvasive Respiratory Support.

Noninvasive respiratory support delivered through a face mask has become a cornerstone treatment for adults and children with acute or chronic respiratory failure. However, an imperfect mask fit by using commercially available interfaces is frequently encountered, which may result in patient discomfort and treatment inefficiency or failure. To overcome this challenge, over the past decade, increasing attention has been given to the development of personalized face masks, which are custom-made to address the specific facial dimensions of an individual patient. With this scoping review, we aim to provide a comprehensive overview of the current advances and gaps in knowledge with regard to the personalization masks for CPAP and NIV. We performed a systematic search of the literature and identified and summarized a total of 23 studies. Most studies included were involved in the development of nasal masks. Studies that targeted adult respiratory care mainly focused on chronic (home) ventilation and included some clinical testing in a relevant subject population. In contrast, pediatric studies focused mostly on respiratory support in the acute setting, whereas testing was limited to bench or case studies only. Most studies were positive with regard to the performance (ie, comfort, level of air leak, and mask pressure applied to the skin) of personalized masks in bench testing or in human, healthy or patient, subjects. Advances in the field of 3-dimensional scanning and soft material printing were identified, but important gaps in knowledge remain. In particular, more insight into cushion materials, headgear design, clinical feasibility, and cost-effectiveness is needed before definite recommendations can be made with regard to implementation of large-scale clinical programs that personalize noninvasive respiratory support masks for adults and children.

Analysis of tribological behavior, pin temperature, and surface roughness of a brake pad material with nano coating

The present work is concentrated on the novel multi-nano particle coating of CoNiCrAlY matrix on brake pad material. The tribological behavior of plasma sprayed CoNiCrAlY particle composite coating with nano inert particles like ZrO2, Al2O3, and AT40 were compared. A comparison was made with respect to structure and morphology of coating. The coatings were characterized with Scanning electron microscopy(SEM) and Energy dispersive X-ray spectroscopy(EDAX) technique. The tribological performance of these coatings were studied using pin-on-disc test rig under dry sliding conditions. The wear study revealed CoNiCrAlY+nano Al2O3 particle coating showed better specific wear rate compared to ZrO2 and AT40 composite coating. The observed tribological behaviour is very much influenced by the ability of nano particles to get distributed in the CoNiCrAlY matrix. The CoNiCrAlY coating with nano particles showed significant specific wear resistance of brake pad material. They coated samples also resulted in minimum rise in pin temperature. This is attributed to the homogeneous distribution of nano particles in the coating. These composite coating also showed lower coefficient of friction values. Although referring to other simplified and extreme conditions, the results obtained provides a new window for using nano hard coatings to enhance the life and efficiency of the commercially available four-wheel vehicle brake pad.

The Impact of Dissolved Salts on the Erosion of Physically Purified Compacted Bentonite

Compressed bentonite is an appropriate cushion material for getting rid of spent nuclear waste below the surface storage. The contact of compressed bentonite with water, its immersion in water and subsequently its swelling into the neighboring gaps are the principal processes for the development of colloid fines. In this study, to examine the impact of ionic strength on the erosion of compacted bentonite, only the ionic power values of the water contacting the bentonite were changed by keeping the flow rates constant. Sodium chloride was used to change the ionic power of the water contacting the bentonite throughout the experiment. Turbidity meter (TM) was used to determine the amount of eroded particles. The dissolution of bentonite fragments is critical not only due to their physical stability but also due to the radioactive isotopes they contain. An experimentation methodology is introduced. The implemented flow rates were 0.06 ml/min and 0.22 ml/min, and the selected waters were distilled water and 0.05 M NaCl ionic strength water. The dry densities of the compressed bentonite samples used were 1.67 g/cm3, 1.72 g/cm3, 1.72 g/cm3 and 1.72 g/cm3. With distilled water, the total erosion value measured at the end of the 24th day using a flow rate of 0.06 ml/min was 1002.7 mg, whereas the final erosion value measured at the end of the 24th day using water containing 0.05 M NaCl salt was 31.13 mg. In the case of distilled water, the total erosion value measured at the end of the 24th day using a flow rate of 0.22 ml/min was 1774.85 mg, while the total erosion value measured at the end of the 24th day using water containing 0.05 M NaCl salt was 73.6 mg. This demonstrates that the influence of the ionic strongness of the water on erosion is too important to be neglected.