Abstract: Thermoplastic urethane (TPU) nonwoven is characterized by high elasticity, tensile strength, large elongation and structural stability and widely used in biomaterial. However, the hydrophobic nature of TPU nonwoven restricts its application. To improve surface hydrophilicity and hydrophobicity, the surface modification of materials is carried out by plasma treatment or ion-beam irradiation. According to the wettability treatment experiences that substrate usually using two processing or more to get one side hydrophilic and another side hydrophobic. In this study, use of cold plasma treatment in enhancing surface wettability of TPU nonwoven was studied. The surface properties of plasma treated films are characterized by Atomic Force Microscope (AFM), water contact angle measurement, and scanning electron microscopy (SEM). This study has demonstrated that Argon plasma treatment produces hydrophobic or hydrophilic surface on the TPU nonwoven. The method is performed by first placing a hydrophobic material on one side of substrate and bring this side to face the lower electrode. By controlling the RF power of the reactor, hydrophilic or hydrophobic surface can be prepared on the other side. This technique can be applied to wound dressing.
Abstract: In order to generate bactericidal effects in the oral cavity, several alternatives have been studied, including the use of silver nanoparticles but presents problems such as toxicity and low biocompatibility. From human-inspired systems, the antibacterial efficiency of the hydroxyapatite nanoparticles depends strongly on the type of composites and nanoparticles size. Several types of hydroxyapatite nanoparticles and their derivatives have received much attention for their antibacterial potential effect, including magnesium oxide nanoparticles. The purpose of this research was to produce a biocompatible antimicrobial compound of nanoparticles of hydroxyapatite doped with magnesium oxide to generate antibacterial effects in the oral cavity. The solvothermal method was used to produce hydroxyapatite nanoparticles doped with magnesium oxide. Antibacterial activity of as synthesized nanopowders against cariogenic Streptococcus mutans was tested by the CLSI disk-diffusion method. As result of this research, hydroxyapatite doped with magnesium nanoparticles (nHAMg) were successfully synthetized by the solvothermal method where in structural characterization indicates magnesium substitution and FTIR analysis gives a broader spectrum of the nHAMg when compared to pure nHA and crystallite size of nHA decreased. Furthermore, results of antibacterial assays showed that nHAMg allow to inhibit the grown of S. mutans by showing a halo of inhibition around the discs. Moreover, this antibacterial activity is enhanced by the addition of silver ion in an amount below to known toxic concentration, showing a synergetic effect that can further potentiate even more these HA nanoparticles. This work demonstrates that solvothermal method is a promising synthesis way for producing antibacterial hydroxyapatites nanoparticles for biomedical applications such as oral tissue regeneration.
Abstract: Tin oxide material has been extensively used for gas sensing application. Due to high operating temperature of metal oxide gas sensors, around 600 K and long term instability, research has been carried out to improve the material properties and reducing operating temperature. nanostructure materials have shown higher sensitivity and better stability towards gas environment. Air pollutants from automobiles and industry waste are the primary sources of environmental pollutants and there is need to develop low temperature, sensitive and selective gas sensors to monitor the gas content. In this paper, we have discussed the effect of Tungsten (W) doping in SnO2 nanostructures on the structural and gas sensing properties. The nanostructures have been synthesized by thermal evaporation process. The structural and surface morphology studies confirm the growth of nanowires on silicon substrates. The corresponding EDX spectra also confirm the doping of W into SnO2 nanowires. The gas sensor response of W-doped SnO2 nanowires was investigated upon exposure to various gases. It has been observed that doping of W enhances the NO2 sensitivity of nanowire based sensors at low temperature and the sensor response improves with increase in gas concentration.
Abstract: The He separation performance of the N-modified graphdiyne monolayer (N-GDY) was studied by using both the first-principles density functional theory (DFT) and molecular dynamics (MD) simulations. The high cohesive energy of 7.24 eV/atom confirmed the strong stability of N-GDY for a gas separation membrane. Based on the calculations, the N-GDY membrane was found to exhibit extremely high He permeance (4.8 ×10-3 mol/m2·s·Pa at 100 K) and selectivities of He/H2O, He/Ar, He/N2, He/CO, He/CO2, and He/CH4 (102~1012 at 300 K). Therefore, N-GDY should be a good candidate for He separation from natural gas.
Abstract: In this work, we designed and synthesized two photoresponsive materials with 3-indoleacetic acid (IAA) plant hormone which can be monitored from the photoreposive properties of coumarin. The varied position of the long alkoxy side chain (-OC16H33) was purposely introduced to adhesive on the plant leaves. Two coumarin-caged nanomaterials showed average particle diameter about 400 nm and gave the maximum emission wavelength at 425 and 450 nm. The formulated nanoemulsion showed good wettability (θ=48o) with Cassia fistula leave surface. Interestingly, CM2 gave the short photoresponse of photolysis within one day.
Abstract: To describe the thermal stability of the nanocrystalline solid solution with weak segregation such as Cu-Zn system, we developed a hybrid model combining the first principles calculation and thermodynamic evaluation. The dependence of the solute segregation behavior on the solute concentration, grain size and temperature were demonstrated. We found that the segregation energy does not change with the solute concentration monotonically. At a constant solute concentration and a given temperature, a nanograin structure can remain stable if the initial grain size is kept in a critical range. The model predictions were confirmed by the experimental measurements that a state of steady nanograin growth can be achieved by designing a certain solute concentration and a proper initial grain size.
Abstract: This paper studies the structure and mechanical properties of the Mg-1%Zn-xCa system subjected to high-pressure torsion (HPT) treatment. It was found that the chemical composition had a notable effect on the processes of grain refinement in the alloy. As is shown, HPT of Mg-1%Zn-0.005%Ca resulted in the formation of grains with a mean size of 250 nm, while HPT of the alloy with an increased content of Са up to 0.2% led to the formation of a nanostructure with a mean grain size of 90 nm. It is demonstrated that high microhardness is typical of all HPT-processed samples. The formation of fine Mg2Ca particles was established to increase the heat resistance of the alloy.
Abstract: The following paper deals with the manufacturing of composite and hybrid materials by using semi-solid forming technologies. On the one hand, there is presented a process for producing Interpenetrating Phase Composites (IPC) consisting of ceramic open-cell structures which are infiltrated by a semi-solid aluminium alloy. On the other hand, a new process for manufacturing hybrid metallic materials is described. Thereby, semi-finished materials made of two different aluminium alloys are simultaneously heated using an induction system and subsequently formed in the semi-solid state. The paper shows numerical investigations as well as experimental results for both processes.
Abstract: The sintering methods of quartz sand porous ceramics were researched with the low grade quartz sand along the Yangtze River via the vacuum sintering method in this paper, which lay technology foundation for researching new heat insulating materials. The quartz porous ceramics is obtained with the high performance cost, the quartz porous ceramics is sintered at 1050°C via the vacuum conditions, the density of ceramics is 1.267g/cm3, the porosity is 51.6%, the compressive strength is 3.184MPa, the porous ceramics show the homogeneous distribution micro-pore and good shape. The density and the compressive strength of prepared ceramics via the vacuum sintering both are higher than that of prepared ceramics via the atmosphere sintering, however, the porosity is shown the opposite results.