Tribological Properties of Novel Multi-Walled Carbon Nanotubes and Phosphorus Containing Ionic Liquid Hybrids in Grease

A continuing quest exists to develop high-performance grease capable of meeting extreme demands of high energy efficiency and durability of modern mechanical systems. In this study, multi-walled carbon nanotubes (MWCNT) and ionic liquids (IL) either singly or as a binary additive system were prepared to study the tribological performance of lithium greases under boundary lubrication condition. The combination of MWCNT and IL can benefit from their respective lubricating mechanism to minimize friction and wear. To test this hypothesis, MWCNT and IL are tested individually and compared with combined MWCNT-IL additive mixture within lithium-based greases. MWCNT-IL gelatinous hybrids were prepared by inducing physical non-covalent interactions between MWCNTs and phosphorous based ILs through ultrasonication and magnetic stirring. Four different phosphorous based ILs, Choline bis (2-ethylhexyl)-phosphate, Choline dibutyl-dithiophosphate, Methyl-tributyl-phosphonium dimethyl-phosphate, Tetra-n-butyl-phosphonium O,O-diethyl-dithiophosphate were used. Four ball tribological test configuration was used to assess wear and friction properties of fabricated greases. The lubrication mechanism of these additives was elucidated through analysis of worn surfaces using surface characterization techniques like SEM, EDS, and stereo optical microscopy. All greases that contain ionic liquid exhibited better tribological performance compared to grease with ZDDP. The maximum reduction of the coefficient of friction (COF) of 60% and wear scar diameter (WSD) reduction of 25% was observed for greases containing MWCNTs and phosphonium cation based ILs hybrids as an additive. Results indicated either worse or comparable anti-wear behavior in greases with MWCNT-IL hybrids as compared to greases that only contained IL or MWCNT. The antagonistic interaction between MWCNT and IL has been postulated to occur when MWCNT adversely interacts with IL formed tribofilms, negating the benefit from IL resulting in increased wear in greases with binary mixtures of MWCNT-IL

Controlled release nanoparticulate matter delivery system

A controlled release nanoparticulate matter delivery system includes a plurality of thermoresponsive modules containing a respective nanoparticulate matter. Each thermoresponsive module is selectively operable in at least one of a heating mode that releases the nanoparticulate matter and a cooling mode that inhibits release of the nanoparticulate matter. A control module is in electrical communication with the plurality of thermoresponsive modules. The control module is configured to determine a temperature of each thermoresponsive module and to select the at least one heating mode and cooling mode based on the temperature. The heating and cooling mode may be selected in response to a desired dosing profile and/or a biometric condition.Board of Regents, University of Texas Syste

Mechanism of Friction and Wear in MoS2 and ZDDP/F-PTFE Greases under Spectrum Loading Conditions

Two different greases formulated using MoS2 and a combination of ZDDP and functionalized PTFE (F-PTFE) were examined under spectrum loading conditions where loads, frequency, and duration of the steps were treated as variables. Combination of ZDDP and F-PTFE were synergistic resulting in a significant reduction in the wear and friction under spectrum loading condition. Decreasing the time step during the ramp up and ramp down cycles resulted in larger wear for the grease containing MoS2 particles in comparison to ZDDP/F-PTFE in grease. The tribofilm formed on the surface was analyzed using various characterization techniques like SEM, EDS, and Stereo Optical Microscopy. Tribofilms from MoS2 additives had extensive amounts of abrasive and adhesive wear and showed the formation of MoS2 on the surface on the other hand the tribofilms from ZDDP/F-PTFE had smaller amounts of severe wear and exhibited patchy tribofilms of Zn-phosphates as well as sulfides of Zn and Fe

Properties of Concrete with Tire Derived Aggregate Partially Replacing Coarse Aggregates

Tire derived aggregate (TDA) has been proposed as a possible lightweight replacement for mineral aggregate in concrete. The role played by the amount of TDA replacing coarse aggregate as well as different treatment and additives in concrete on its properties is examined. Conventional concrete (without TDA) and concrete containing TDA are compared by examining their compressive strength based on ASTM C39, workability based on ASTM C143, splitting tensile strength based on ASTM C496, modulus of rupture (flexural strength) based on ASTM C78, and bond stress based on ASTM C234. Results indicate that while replacement of coarse aggregates with TDA results in reduction in strength, it may be mitigated with addition of silica fume to obtain the desired strength. The greatest benefit of using TDA is in the development of a higher ductile product while utilizing recycled TDA

Amorphous silicon oxide, amorphous silicon oxynitride, and amorphous silicon nitride thin films and uses thereof

Amorphous SiOx (SiO2), SiONx, silicon nitride (Si3N4), surface treatments are provided, on both metal (titanium) and non-metal surfaces. Amorphous silicon-film surface treatments are shown to enhance osteoblast and osteoblast progenitor cell bioactivity, including biomineral formation and osteogenic gene panel expression, as well as enhanced surface hydroxyapatite (HA) formation. A mineralized tissue interface is provided using the amorphous silicon-based surface treatments in the presence of osteoblasts, and provides improved bone cell generation/repair and improved interface for secure attachment/bonding to bone. Methods for providing PEVCD-based silicon overlays onto surfaces are provided. Methods of increasing antioxidant enzyme (e.g., superoxide dismutase) expression at a treated surface for enhanced healing are also provided. Continuous generation and release of Si4+ ion into an in vitro or in vivo environment in the presence of osteoblasts/osteoblast progenitor cells, methods of employing same for enhancing the rate of bone healing/bone regeneration, is also described.U

Silicon Ions Enhance Myogenic Differentiation in C2C12 Skeletal Muscle Cells

The regeneration of bone and muscle tissue following musculoskeletal injuries is essential in sports medicine in order to restore function and prevent chronic musculoskeletal disorders related to physical inactivity. According to data collected by the American Academy of Orthopaedic Surgeons from 2012 to 2014, 8.3% (approximately 2.6 million people) of the adult population in the United States received treatment for musculoskeletal injuries, costing an aggregate total of $213 billion dollars. Recent regenerative musculoskeletal research suggests that the restoration of function and structure for normal physical activity is dependent on the synergy of regeneration processes found in bone and muscle tissue. Current treatments for severe musculoskeletal defects lack biocompatibility and rarely restore full function, so focus has shifted to regenerative biomaterials. Recent evidence indicates that bioactive gels and implants incorporating silicon (e.g. silicon ion, orthosilicate acid, amorphous silica) markedly increased osteogenesis in vitro, but little research has been conducted over the effect of these biomaterials on myogenesis. Establishing the existence of myogenic properties in silicon could lead to the development of a biomaterial that enhances the synergistic capacities of bone and muscle regeneration. PURPOSE: The purpose of this study was to investigate the effect of silicon ions on C2C12 skeletal muscle cells in vitro, in order to determine the regenerative viability of musculoskeletal gels and implants incorporating silicon. METHODS: In order to evaluate the effect of Silicon ions on myogenesis, in vitro cell culture studies were performed using C2C12 mouse myoblast cell lines. Cells were differentiated for four and seven days in media containing three different concentrations of silicon ions (0.1, 0.5, and 1.0 mM) and a silicon free control. Samples were immunohistochemically stained and imaged using a Zeiss fluorescent microscope. Cellsens software was used to determine total nuclei count and ImageJ was used to count the number of fused nuclei within myotubules. Rates of myogenic differentiation were determined based on fusion index, the percent of nuclei found within myotubes relative to the total nuclei. RESULTS: After four days there was a significant increase in fusion index (p\u3c0.001) in the 0.1mM group (41±3.4) compared to the control (31±4.2) . After seven days all three silicon groups exhibited significantly higher fusion indices (0.1mM 60±3.2, p\u3c0.001; 0.5mM 57.8±2.9, p\u3c0.01; 1.0mM 54.8±3.6 p\u3c0.05) compared to the control (50±2.4). Both four and seven day studies confirmed that the 0.1 Mm group had a markedly higher fusion index, indicating the highest rate of myogenic differentiation. CONCLUSION: Based on these results it can be concluded that silicon ions enhance myogenic differentiation. The myogenic potential of silicon ions exhibited by these results, combined with previously reported osteogenic effects, prompt further investigation into the potential of silicon-containing biomaterials to accelerate musculoskeletal regeneration, and decrease the risk of acute and chronic complications of injury

Si--O--N--P related fabrication methods, surface treatments and uses thereof

Disclosed are compositions, methods and processes for fabricating and using a device or other implement including a surface or surfaces having a nanoscale or microscale layer or coating of Si--O--N--P. These coatings and/or layers may be continuous, on the surface or discontinuous (e.g., patterned, grooved), and may be provided on silica surfaces, metal (e.g., titanium), ceramic, and combination/hybrid materials. Methods of producing an implantable device, such as a load-bearing or non-load-bearing device, such as a bone or other structural implant device (load-bearing), are also presented. Craniofacial, osteogenic and disordered bone regeneration (osteoporosis) uses and applications of devices that include at least one surface that is treated to include a nanoscale or microscale layer or coating of Si--O--N--P are also provided. Methods of using the treated and/or coated devices to enhance enhanced vascularization and healing at a treated surface of a device in vivo, is also presented.U

Structure and Chemistry of Soot and Its Role in Wear of Diesel Engines

Environmental regulations to reduce the emissions using exhaust gas recirculation (EGR) have resulted in higher soot level in the crankcase oil of diesel engines. Longer drain intervals have resulted in engines running 80000 kilometers or more before an oil change. This results in longer residence times of EGR soot in the crankcase and other parts of the engine drivetrain. The primary structure of soot from in-cylinder combustion is turbostratic carbon, as soot spends more time in the combustion chamber and in the crankcase it incorporates some of the chemistry of the aged oil as well as debris from the wear processes making the soot more abrasive. This study focuses on the use of multiple tools to examine the nature of soot from different engines of the same type but different age all using the same engine oil and similar duty cycles. This soot is compared with soot derived from a typical EGR diesel engine driven for a period of 80000 kilometers

In vivo live 3D printing of regenerative bone healing scaffolds for rapid fracture healing

Bio-Inks and methods of using compositions comprising the bio-Inks are disclosed. 3-D tissue repair and regeneration through precise and specific formation of biodegradable tissue scaffolds in a tissue site using the bio-inks are also provided. Specific methylacrylated gelatin hydrogels (MAC) and methacrylated chitosan (MACh) preparations formulated with sucrose, a silicate-containing component (such as laponite), and/or a cross-linking agent (such as a photo-initiator or chemical initiator), as well as powdered preparations of these, are also disclosed. Kits containing these preparations are provided for point-of-care tissue repair in vivo. Superior, more complete (up to 99.85% tissue regeneration within 4 weeks applied in situ), and rapid in situ tissue repair and bone formation are also demonstrated.U

In vivo live 3D printing of regenerative bone healing scaffolds for rapid fracture healing

Bio-Inks and methods of using compositions comprising the bio-Inks are disclosed. 3-D tissue repair and regeneration through precise and specific formation of biodegradable tissue scaffolds in a tissue site using the bio-inks are also provided. Specific methylacrylated gelatin hydrogels (MAC) and methacrylated chitosan (MACh) preparations formulated with sucrose, a silicate-containing component (such as laponite), and/or a cross-linking agent (such as a photo-initiator or chemical initiator), as well as powdered preparations of these, are also disclosed. Kits containing these preparations are provided for point-of-care tissue repair in vivo. Superior, more complete (up to 99.85% tissue regeneration within 4 weeks applied in situ), and rapid in situ tissue repair and bone formation are also demonstrated.U