Mcgeesharp1097

Human joints support us to reduce the impact on our body and move them smoothly. As they are composed of gel-like structures, gel materials with soft and resilient properties are expected, as lubricants, to provide high efficiency and a long lifetime for mechanical parts. While double network gels including ionic liquids as swelling agents possess high mechanical strength and stable low friction under high temperature or vacuum, their fabrication process is complex and time-consuming. In this study, we applied one-pot synthesis to a double network ion gel (DNIG) to obtain a thin gel film by a simple coating method and examined its thermal, mechanical and tribological properties. The DNIG was obtained by one-pot synthesis (DNIG-1) combining polycondensation of tetraethoxysilane and radical polymerization of methyl methacrylate to form silica and poly(methyl methacrylate) as a 1st and 2nd network, respectively. Such obtained DNIG-1 was characterized and compared with DNIG obtained by a conventional two-step process (DNIG-2). Thermogravimetric analysis and the compressive stress-strain test showed high thermal stability and mechanical strength of DNIG-1. As friction at the glass/DNIG-1 interface showed high friction compared with that at glass/DNIG-2, various counterface materials were applied to examine their effect on the friction of DNIG-1. As SUS304/DNIG-1 showed much lower friction compared with glass/DNIG-1, the difference in the friction was presumably due to the different adsorption forces and compatibility between the materials.Although several studies indicated that the addition of Styrene-Butadiene-Styrene (SBS) and Styrene-Butadiene Rubber (SBR) bring a lot of benefits on properties of asphalt binders, high production costs and poor storage stability confine the manufacture of better modified asphalt. To reduce the production costs, polyphosphoric acid (PPA) was applied to prepare better compound modified asphalt binders. In this research, five PPA (0.5%, 0.75%, 1.0%, 1.25% and 1.5%) and two SBR/SBS (4% and 6%) concentrations were selected. Dynamic shear rheometer (DSR) and Bending Beam Rheometer (BBR) tests were performed to evaluate the rheological properties of the compound modified asphalt. Rolling Thin Film Oven (RTFO) test was performed to evaluate the aging properties of the compound modified asphalts. The results indicate that SBS/SBR modified asphalts with the addition of PPA show better high-temperature properties significantly, the ability of asphalt to resist rutting is improved, and the elastic recovery is increased. However, the low-temperature properties of the compound modified asphalts are degraded by increasing the creep stiffness (S) and decreasing the creep rate (m). At the same time, RTFO tests results show that PPA was less prone to oxidation to improve the anti-aging ability of modified asphalts. Overall, the combination of 4% SBS and 0.75-1.0% PPA, the combination of 4% SBR and 0.5-0.75% PPA is recommended based on a comprehensive analysis of the performance of compound modified asphalt, respectively, which can be equivalent to 6% SBS/SBR modified asphalt with high-temperature properties, low-temperature properties, temperature sensitivity and aging properties.Functional nanoporous materials are categorized as an important class of nanostructured materials because of their tunable porosity and pore geometry (size, shape, and distribution) and their unique chemical and physical properties as compared with other nanostructures and bulk counterparts. Progress in developing a broad spectrum of nanoporous materials has accelerated their use for extensive applications in catalysis, sensing, separation, and environmental, energy, and biomedical areas. The purpose of this review is to provide recent advances in synthesis strategies for designing ordered or hierarchical nanoporous materials of tunable porosity and complex architectures. Furthermore, we briefly highlight working principles, potential pitfalls, experimental challenges, and limitations associated with nanoporous material fabrication strategies. Finally, we give a forward look at how digitally controlled additive manufacturing may overcome existing obstacles to guide the design and development of next-generation nanoporous materials with predefined properties for industrial manufacturing and applications.High-energy heavy ion irradiation can produce permanent damage in the target material if the density of deposited energy surpasses a material-dependent threshold value. It is known that this threshold can be lowered in the vicinity of the surface or in the presence of defects. In the present study, we established threshold values for Al2O3, MgO and CaF2 under the above-mentioned conditions, and found those values to be much lower than expected. By means of atomic force microscopy and Rutherford backscattering spectrometry in channelling mode, we present evidence that ion beams with values of 3 MeV O and 5 MeV Si, despite the low density of deposited energy along the ion trajectory, can modify the structure of investigated materials. The obtained results should be relevant for radiation hardness studies because, during high-energy ion irradiation, unexpected damage build-up can occur under similar conditions.The substitution of river sand with glass aggregate (GA) and cement with glass powder (GP) is a mainstream method to recycle waste glass. Traditionally, standard curing was widely used for glass-based mortars. However, it is time-consuming and cannot address low mechanical strengths of the early-age mortars. Therefore, the effect of water curing at 80 °C on the properties of GA mortars is investigated. Furthermore, the effect of the GP size is also considered. Results show that compared with the expansion of alkali-silica reaction (ASR), water curing at 80 °C has a negligible effect on the volume change. Moreover, the compressive strength of GA mortars under 1-day water curing at 80 °C is comparable with that under 28-day water curing at 20 °C. Therefore, the 1-day water curing at 80 °C is proposed as an accelerated curing method for GA mortars. On the other hand, the addition of GP with the mean size of 28.3 and 47.9 μm can effectively mitigate the ASR expansion of GA mortars. Compared with the size of 28.3 μm, GA mortars containing GP (47.9 μm) always obtain higher compressive strength. In particular, when applying the 1-day water curing at 80 °C, GA mortars containing GP (47.9 μm) can even gain higher strength than those containing fly ash.In this study, a numerical and experimental investigation of the quasi-static crushing behavior of steel tubular structures was conducted. As the crushing failure behavior involves a high level of nonlinearity for the numerical simulations, these were compared with previous experimental works, including crushing tests of steel square tubes to calibrate the numerical results. Six parameters for the numerical simulations, namely (1) loading boundary condition, (2) geometrical imperfection, (3) friction coefficient, (4) element size, (5) element type, and (6) material nonlinearity model, were examined using a series of finite element analyses. Through the sensitivity study for each parameter, the deformation and crushing load of the steel tube were investigated, and the value that best matched the experimental results was selected. The results of the numerical analysis for the determined model were compared with the experimental results. Finally, the authors provided recommendations that should be considered when performing nonlinear finite element simulations of crushing failure events.In this paper, a frequency-adjustable tuning fork electromagnetic energy harvester is introduced. The electromagnetic vibration energy harvester can adjust its natural frequency according to a change in the environmental excitation frequency without any change to the structure. see more In the frequency-adjustable range, it can make the energy harvester resonant with the environment excitation, and the output frequency stays the same. The frequency-adjustable tuning fork electromagnetic energy harvester significantly increases the range of frequencies used. The operating frequency of the centre can be easily switched from 9.2 to 20 Hz, enabling the application of multiple excitation frequencies. In addition, the output power and power density are significantly increased compared to a piezoelectric tuning fork energy harvester of the same size. The peak power is 23.59 mW at 9.2 Hz, the power increases by 14.85 mW, and the power density increases by 169.88%. The experimental results show that the electromagnetic tuning fork frequency-adjustable conversion energy harvester can make the LED lamp work.This article reports an extended investigation into the precision hard turning of AISI 4340 alloy steel when machined by two different types of inserts wiper nose and conventional round nose. It provides a closer look at previously published work and aims at determining the optimal process parameters for simultaneously minimizing surface roughness and maximizing productivity. In the mathematical models developed by the authors, surface roughness at different cutting speeds, depths of cut and feed rates is treated as the objective function. Three robust multi-objective techniques, (1) multi-objective genetic algorithm (MOGA), (2) multi-objective Pareto search algorithm (MOPSA) and (3) multi-objective emperor penguin colony algorithm (MOEPCA), were used to determine the optimal turning parameters when either the wiper or the conventional insert is used, and the results were experimentally validated. To investigate the practicality of the optimization algorithms, two turning scenarios were used. These were the machining of the combustion chamber of a gun barrel, first with an average roughness (Ra) of 0.4 µm and then with 0.8 µm, under conditions of high productivity. In terms of the simultaneous achievement of both high surface quality and productivity in precision hard turning of AISI 4340 alloy steel, this work illustrates that MOPSA provides the best optimal solution for the wiper insert case, and MOEPCA results are the best for the conventional insert. Furthermore, the results extracted from Pareto front plots show that the wiper insert is capable of successfully meeting both the requirements of Ra values of 0.4 µm and 0.8 µm and high productivity. However, the conventional insert could not meet the 0.4 µm Ra requirement; the recorded global minimum was Ra = 0.454 µm, which reveals the superiority of the wiper compared to the conventional insert.The present study aimed to prepare nanofibers by electrospinning in the system polylactic acid-hydroxyapatite-doxycycline (PLA-HAP-Doxy) to be used as a drug delivery vehicle. Two different routes were employed for the preparation of Doxy-containing nanofibers Immobilization on the electrospun mat's surface and encapsulation in the fiber structure. The nanofibers obtained by Doxy encapsulation were characterized using Fourier transform infrared (FTIR) spectroscopy, thermogravimetric (TG) and differential thermal analyses (DTA) and scanning electron microscopy (SEM). The adsorption properties of pure PLA and PLA-HAP nanofibers were investigated for solutions with different Doxy concentrations (3, 7 and 12 wt%). Moreover, the desorption properties of the active substance were tested in two different fluids, simulated body fluid (SBF) and phosphate buffer solution (PBS), to evidence the drug release properties. In vitro drug release studies were performed and different drug release kinetics were assessed to confirm the use of these nanofiber materials as efficient drug delivery vehicles.