High Contact Surface Research Articles

Lead Crowning and Anti-Twist for Tooth Flank of a Heat Treated Helical Gear on Internal CNC Honing Machine

The internal gear honing is more popular than the external gear honing by its advantages such as higher contact surface and easier correct profile errors. It is usually applied for modifying the gear surface to compensate for the distortions after heat treatment process. However, the lead crowning and anti-twist tooth flank of a helical gear on internal CNC gear honing has not studied yet. Therefore, a novel method for lead crowning tooth flank of work gear surfaces is proposed by using a linear swivel angle function of the honing wheel and a variable pressure angle (VPA) honing wheel is also applied for anti-twist of the crowned tooth flank in honing process.

Impact of aluminum wire and ribbon bonding technologies on D2PAK package reliability during thermal cycling applications

This paper highlights the impact of bonding techniques (Al wire and Al ribbon) on the aging of Schottky diodes, assembled in D2PAK package, subjected to temperature cycling. The experimental test results coupled with failure analyses exhibit a better robustness and a lifetime about 2.3 times higher for the ribbon bonding assembly. A higher contact surface, the low loop profile and stiffness of ribbons allow slowing down crack initiation and propagation between the Al bond and Al metallization on the top of the silicon die.

Joining of carbon fiber reinforced polymer laminates by a novel partial cross‐linking process

ABSTRACTDirect joining of partially cross‐linked and freshly infiltrated carbon fiber reinforced epoxy resin plates made from HTA/RTM6 is investigated as function of the partial curing degree. Partial cross‐linking maintains a certain chemical reactivity of the thermosetting resin which can be used for bonding to a second, freshly infiltrated resin part. A final curing cycle guarantees complete cross‐linking of the joined component. The bonding behavior and the interface morphology of the joined plates are analyzed by mechanical testing, acoustic emission analysis and microscopy. A significant dependence of the bonding and interfacial properties on the partial curing degree is found. Very low and very high partial curing degrees (below 70% and above 80%) result in low fracture toughness and discontinuous crack propagation. Intermediate curing degrees between 70% and 80% mainly show high fracture toughness, stable crack propagation and a ripple like interface morphology. The latter is created by the surface morphology of the partially cross‐linked plate with the typical peel‐ply imprint and results in a high contact surface and mechanical interlocking. The combination of chemical reactivity and high contact surface seems to be advantageous for the enhanced fracture toughness and the improved failure mode of samples with intermediate partial curing degree. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42159.

Determination of β-caryophyllene skin permeation/retention from crude copaiba oil (Copaifera multijuga Hayne) and respective oil-based nanoemulsion using a novel HS-GC/MS method

Copaiba oil is largely used in the Amazonian region for the treatment of inflammation, and recent studies demonstrated that one of the major components of the oil, β-caryophyllene (CAR), is a potent anti-inflammatory. The nanoemulsification of this oleoresin, which has unctuous character, converts it in a more acceptable hydrophilic formulation and may improve CAR penetration through the skin due to the small droplet size and the high contact surface afforded by the nanoemulsions. This paper describes the validation of a novel, sensitive, practical and solvent free method that uses gas chromatography in headspace mode coupled with mass spectrometry to evaluate the skin permeation/retention of CAR from the crude copaiba oil and its nanoemulsion. Our results show that the bioanalytic method was fully validated, demonstrating linearity (r2>0.99), specificity (no peaks co-eluting with CAR retention time), precision (RSD<15%) and accuracy (recovery>90%) within the accepted parameters and that the copaiba oil nanoemulsion presented a better skin penetration compared to the crude oil, with CAR achieving the most profound layer of the skin, the dermis.

Performance of lithium ion batteries using a carbon nanotube film as a cathode current collector

A carbon nanotube (CNT) film was used as the current collector and LiCoO 2 as the cathode for a lithium ion battery. The battery showed a high initial discharge capacity of 132.8 mAh g −1 , a high retention rate of over 80% after 500 cycles under 1 C and a low self-discharge rate of 1.5%. When the areal density of the CNT film is 16 mg cm −2 , the energy density of the LiCoO 2 –CNT battery is 25% larger than that of a LiCoO 2 –Al battery. The superior properties of the battery may be attributed to the high electrochemical stability of the graphitic structure of CNTs and the porous surface of the CNT film that ensures a high contact surface area between the current collector and the cathode material. The CNT film is promising as a new current collector for lithium ion batteries. [New Carbon Materials 2014, 29(4): 322–328]

Assessing the Level of Bioburden and Rate of Contamination of High Contact Surfaces in Private, Semi-private and Ward Patient Rooms

Contamination of environmental surfaces in patient rooms presents a potential for transmission of healthcare-associated pathogens. The level and rate of contamination may be linked to the Number of patients per room and the type of high contact surface. A quantitative assessment of bioburden on high contact surfaces in the patient environment, pre- and post-cleaning was conducted and the rebound time to pre-cleaning levels in private, semi-private and ward rooms was compared.

Self-Supported Li4Ti5O12–C Nanotube Arrays as High-Rate and Long-Life Anode Materials for Flexible Li-Ion Batteries

Self-supported Li4Ti5O12-C nanotube arrays with high conductivity architectures are designed and fabricated for application in Li-ion batteries. The Li4Ti5O12 nanotube arrays grow directly on stainless steel foil by a facile template-based solution route, further enhancing electronic conductivity by uniform carbon-coating on the inner and outer surfaces of Li4Ti5O12 nanotubes. Owing to the shortened Li(+) diffusion distance, high contact surface area, sufficient conductivity, and very good structure stability of the nanotube arrays, the self-supported Li4Ti5O12-C nanotube arrays exhibit remarkable rate capability (a reversible capability of 135 mA h g(-1), 105 mA h g(-1), and 80 mA h g(-1) at 30C, 60C, and 100C, respectively) and cycling performance (approximate 7% capacity loss after 500 cycles at 10C with a capacity retention of 144 mA h g(-1)).

Enhancement in supercapacitive properties of CuO thin films due to the surfactant mediated morphological modulation

The complex hierarchical CuO nanostructures (woolen clumps, stacked nanosheets and nanobuds) have been developed through a chemical bath deposition method using surfactant assisted approach. The morphology of CuO nanostructures can be easily tuned using different surfactants as a soft chemical template. Nanobuds clusters deliver a superior 3D conductive framework, which allows well electrolytic accessible surface area and provides a shortest path for ions. The porous and well defined nanostructure renders a high contact surface area for the intercalation/deintercalation of ions into/out of active materials and reduces the path length for electrolyte ion transport. The maximum specific capacitance of 396Fg−1 at 5mVs−1 is calculated for CuO nanobuds structured electrode. Moreover, all the CuO nanostructures reveal better power performance, excellent rate as well as long term cycling stability. Such a study will encourage for the preparation of 3D nanostructures framework of the other materials using surfactant assisted approach.

Thermal decomposition of calcium carbonate polymorphs precipitated in the presence of ammonia and alkylamines

Precipitated calcium carbonate was obtained by CO2 bubbling in CaCl2 solution. Ammonia and alkylamines were used to enhance CO2 absorption and control the polymorphic phases. Vaterite and calcite mixtures were obtained, mainly vaterite in ammonia and mono-methylamine and mostly calcite in tri-methylamine environment. The thermal decomposition of precipitated calcium carbonate leads to high purity CaO. During the thermal decomposition the vaterite to calcite transformation was noticed but the final spherical shape of vaterite was maintained. As the use of CaO as catalyst in biodiesel synthesis may recommend a spherical shape and high contact surface, a precipitated calcium carbonate, rich in vaterite phase, may be a good precursor for CaO catalyst preparation.

Adsorption kinetics, thermodynamic studies, and high performance of CdO cauliflower-like nanostructure on the removal of Congo red from aqueous solution

In this work, CdO cauliflower-like nanostructure synthesized by mechanochemical method was employed to evaluate the adsorption ability of Congo red (CR) from the aqueous solution for the first time. UV-visible absorption spectroscopy was used to record the adsorption behavior. This special structure composed of nanorods and tubes with the high contact sites and surface area of 104 m2 g−1 can be operated as a capable adsorbent to absorb the dye molecules via adsorption process. The adsorption capacity of this material (0.01 g) was studied in high concentrations of CR (50 to 300 mg L−1) and represented an excellent efficiency to eliminate this toxic dye. Maximum adsorption capacity (qmax) calculated using Langmuir isotherm model, at room temperature and neutral pH, was found to be 588.24 mg g−1. Electrostatic interactions were conceived as the main adsorption mechanism, and the calculated dimensionless separation factor (R L ), 0.023, indicated a favorable adsorption process. The kinetic and thermodynamic parameters for this proceeding were evaluated and confirmed the high performance of the synthesized adsorbent.

Evaluation on tribological design coatings of Al2O3, Ni–P–PTFE and MoS2 on aluminium alloy 7075 under oil lubrication

The current work evaluated the friction and wear properties of tribological design surface coatings on aluminium alloy 7075 under various speed and nominal contact pressure. Hard-anodized Aluminium Oxide (Al2O3), burnished Refractory Metal Sulfide (MoS2) and composite electroless nickel coatings with polytetrafluoroethylene (Ni–P–PTFE) particles were subjected to pin-on-disc sliding test against grey cast iron (GCI) under Mach 5 SL SAE 10W-30 lubrication. The results indicated that Ni–P–PTFE composite coating possessed excellent friction–reduction capability but limited wear resistance due to low mechanical strength. Al2O3 coated sample showed outstanding wear resistance with high friction characteristic leading to high surface contact temperature. Furthermore, MoS2 coating improved the wear resistance of the aluminium alloy.

Comparative Spread of Facultative Anaerobic Bacteria in Inanimate Hospital Environment in One Tertiary Care Hospital in Iran

Inanimate hospital environment can serve as reservoirs of potential pathogen and is important in chain of infection. Health care-associated infections (HAI) remain a major cause of patient morbidity and mortality. In this study we comparative spread of bacteria in high and low contact surfaces in one tertiary care hospital in Iranian. Materials and Materials The present study was performed during a 30 month period a total study 194 environmental Bacteria. Environmental samples collected from low and high contact surface with swab in TSB. Identification of bacteria, were performed with microbiological methods. Results According to result, coagulase negative Staphylococcus species, consist the more bacteria isolated from high and low contact hospital surfaces. Conclusion Some microbes can survive on surfaces for long times. These environmental surfaces can be involved in the transfer of microorganisms to patients and subsequently in the development of hospital-associated infections.

Through-plane thermal conductivity of the microporous layer in a polymer electrolyte membrane fuel cell

Understanding the thermal properties of the microporous layer (MPL) is critical for accurate thermal analysis and improving the performance of proton exchange membrane (PEM) fuel cells operating at high current densities. In this study, the effective through-plane thermal conductivity and contact resistance of the MPL have been investigated. Gas diffusion layer (GDL) samples, coated with 5%-wt. PTFE, with and without an MPL are measured using the guarded steady-state heat flow technique described in the ASTM standard E 1225-04. Thermal contact resistance of the MPL with the iron clamping surface was found to be negligible, owing to the high surface contact area. Effective thermal conductivity and thickness of the MPL remained constant for compression pressures up to 15 bar at 0.30 W/m°K and 55 μm, respectively. The effective thermal conductivity of the GDL substrate containing 5%-wt. PTFE varied from 0.30 to 0.56 W/m°K as compression was increased from 4 to 15 bar. As a result, GDL containing MPL had a lower effective thermal conductivity at high compression than the GDL without MPL. At low compression, differences were negligible. The constant thickness of the MPL suggests that the porosity, as well as heat and mass transport properties, remain independent of the inhomogeneous compression by the bipolar plate. Despite the low effective thermal conductivity of the MPL, thermal performance of the GDL can be improved by exploiting the excellent surface contact resistance of the MPL.

The Processing Method and Discuss of Curved Surface Based on Spatial Linkage Mechanism

Compared with the free surface, the ruled surface is a linear set of parameters, and is obtained by a straight line moving in space along the curve trajectory, and tts modern processing methods are all complex and high cost. Spatial linkage mechanism has many features such as simple structure, easily control, sports continuous and so on, and the initiative crank continuous rotating drives the mechanism, at the same time, the rod length, the motion pair length or the twist angle is changed, which the cutter with start position fixed on a point of the rod main moves along the given curve, and feed moves straightly along the rod itself, so, the ruled surface was processed. The method is uncomplicated, and achieves high efficiency and high precision continuous line contact surface parts finishing, operating easily and saving cost.

Study on fabrication and photoluminescence of SiC nanorods synthesised by carbothermal reduction

SiC nanorods were synthesised from SiO2 xerogel containing carbon nanoparticles at 1550°C in argon flow. The morphology and structure of the materials were determined by transmission electron microscopy, scanning electron microscopy, X-ray diffraction and Raman scattering methods. The static photoluminescence and time-resolved photoluminescence of SiC nanorods were examined under different thermal contact surface areas in the synthesis process. The results showed that products with high thermal contact surface areas have strong photoluminescence. The emission peaks were around 490 nm and shifted to longer wavelength regions when annealed at high temperature. The nature of photoluminescence emission observed in different synthesis conditions is discussed in this report.

The role of methacrylate polymerized as porous‐layered and nanoparticle‐bound phases for open‐tubular capillary electrochromatography: Substitution of a charged monomer for a bulk monomer

The bulk monomer, butyl methacrylate (BMA), was copolymerized with an ionizable monomer (mono-(2-(methacryloyloxy)ethyl) succinate (MES)) and carbon nanotubes (CNTs) by ethylene dimethacrylate (EDMA) crosslinking to form the porous-layered and nanoparticle-bound stationary phases for open-tubular CEC. Here, two new phases were synthesized to check the role of BMA on the BMA-MES and BMA-CNT phases and the suitability of the MES monomer for concurrently acting as a bulk monomer. One phase, MES-EDMA, was simply composed of MES monomer and EDMA crosslinker and exhibited a phase construction of molecular layers, in contrast to the polymeric phases of BMA-MES. Another phase studied was MES-CNT, which SEM images showed that MES could be a good bulk monomer for a CNT-polyacrylate composite phase with embedded CNTs. For all the modified capillaries, the EOF profiles observed in phosphate buffers between pH 3.6 and 9.6 were comparable with each other and conformed to their corresponding SEM images. The residual silanols retained their influence on the EOF profiles in the MES-EDMA and BMA-MES capillaries, but diminished in the CNT-bound capillaries. In a comparison with the MES-EDMA capillary, the BMA-MES capillary afforded a stronger interaction with flavonoids and phenolic acids and still retained positive capacity factor values. Additionally, the capacity factors obtained from the BMA-CNT capillary were higher than those from the MES-CNT capillary, as the BMA-CNT phase had hydrophobic BMA units and a high surface contact area of bound CNTs.

Selective Radioactive Decontamination employing Dual Stimuli Responsive N-Aza crown ether containing polymer hydrogels

AbstractWe report the synthesis and properties of two different hydrogels based on N-isopropylacrylamide/acrylic acid and copolymers of oligo-ethylene glycol methacrylates incorporating N-Aza crown ethers. Both hydrogels show rapid response to environmental stimuli and their size can be tuned by pH and temperature. Swollen states lead to high adsorption of water and high contact surface area with ions whereas in the collapsed state the material releases water and the ions not selectively retained by the polymer.Preliminary autoradiography tests show that these materials strongly bind 90Sr and both pH and temperature can be used to fine tune binding selectivity. This results in such materials being promising candidates for use as smart scavenging agents for radioactive decontamination.

Role of drug substance material properties in the processibility and performance of a wet granulated product

The purpose of this study was to establish a relationship between the material properties of an active pharmaceutical ingredient (API) and its behavior during high-shear wet granulation. Using several actives and excipients as material probes, the influence of aqueous solubility, wettability, water holding capacity, mean and width of the particle size distribution, and surface area was examined. The effect of these variables on the processibility and performance of the granulations was evaluated by monitoring such responses as granule growth, compactability and flow changes upon wet granulation. The prominent findings from this study include: (a) controlled growth is highest in readily wettable APIs with low surface area, (b) uncontrolled growth is high in APIs of high solubility and low water holding capacity, (c) polydisperse granulations are produced from APIs of high contact angle and surface area, (d) improvement in compactability is high in APIs with large surface area and broader size distributions and (e) flow enhancement as a result of wet granulation is highest in APIs of large size distributions. These results are physically interpreted in this manuscript based on the prevailing wet granulation theories. Findings from this study are useful in mapping a new material to predict its performance in a high-shear wet granulation process.

Macronized aligned carbon nanotubes for use as catalyst support and ceramic nanoporous membrane template

An aligned carbon nanotube carpet was synthesized by catalytic chemical vapor deposition (CCVD) process at 800 °C with a mixture of ferrocene and toluene, using a removable quartz substrate as macroscopic pre-form. The strong anchorage of the aligned nanotube array at the macroscopic host surface allows the nano–macro-composite to be considered as a nano-ordered macroscopic material and self-supported aligned nanotubes could be obtained by substrate removal. The carpet thickness could be accurately controlled from few tenth micrometers to more than few millimeters by tuning the synthesis duration. Such a nano–macro-composite could be used as high contact surface catalyst support with low pressure drop. The aligned nanotube array was efficiently used as removable precursor template in the design of β-SiC ceramic nanoporous membranes.

Friction Drive Simulation of Surface Acoustic Wave Motor Characteristics Based on Contact Mechanics

A physical analysis model of a surface acoustic wave (SAW) motor that is driven by frictional force resulting in nanometer elastic vibration has been proposed. In the case of the SAW motor, the vibration amplitude is from 3 to 30 nm at most. The vibration amplitude is almost the same as that of elastic deformation caused by the preload between a slider and a stator. In the analysis model, the elastic deformation, stick, and slip were considered. Numerical simulation was carried out successfully. Experimental results for the SAW motor at 9.6 MHz operation frequency were compared with simulation results. It was observed that a smaller projection slider with many projections has a high contact surface stiffness, thus, superior performances are obtained in terms of speed and thrust.