Refractive index determination in fuel cells using high-resolution laser heterodyne interferometer

In this paper, we present an interferometry method for refractive index determination in membranes of fuel cells. This technique is based on the use of an improved laser heterodyne interferometer. The photocurrents of the avalanche photodiodes, resulting from reflected beams of the optical head, are led to the signal conditioner and digital signal processing sections. The optical path difference between the target and reference paths is fixed, and as a result, the phase shift is calculated in terms of the refractive index shift. In addition, nonlinearity of this system is analyzed and modeled with different neural networks and adaptive filter algorithms. For neural networks, the radial basis function (RBF), the multi-layer perceptron (MLP), and the stacked generalization method are simulated. In adaptive filter algorithms, the least mean square (LMS), the normalized least mean square (NLMS), the recursive least squares (RLS), and the affine projection algorithm (APA) are applied. The simulation results indicate that the RLS method is faster and contains minimum mean square error (MSE) compared to the other approaches. Also, comparison between two main approaches shows that the nonlinearity of refractive index determination can be effectively modeled with adaptive filter algorithms.     

Tuning and optimization of structure and surface properties of thin and fine hydrophilic nanofibrous substrates through low-pressure heat-press treatment

The properties of electrospun nanofibrous membranes (ENMs), including pore size, surface roughness, and hydrophilicity, significantly affect crosslinking, thickness, and morphology of the polyamide selective layer formed on top of ENM substrate in thin film composite membranes, and, ultimately the performance of membranes. We produced polyamide 66 nanofiber layers with a thickness of 10 μm and a fiber diameter of 55 nm, considerably thinner and finer than usual ENM substrates. We then subjected this thin layer to post-production treatment using the efficient low-pressure heat-press (LPHP) method at a pressure of 3 kPa at three different temperatures and two different time intervals. It was found that the morphology of the nanofiber layer was preserved, and its structural characteristics, including pore structure, surface roughness, wettability, crystallinity, and specific surface area, were favorable with LPHP treatment. The optimal conditions were obtained with treatment at 190°C for 3600 s, in which the roughness of the nanofiber substrate decreased from 64 to 25 nm. Using these substrates offers new, less-explored opportunities for optimizing the LPHP treatment of the substrate. These substrates are proposed for a new generation of TFC membranes in a continuous production line, with the possibility of scaling up for pressure- and osmosis-driven membranes.     

An Investigation on Reasons Causing Inferiority in Unlubricated Sliding Wear Performance of 60NiTi as Compared to 440C Steel

60NiTi is gaining recognition as an alternative to 440C steel in ball bearing components due to its intrinsic corrosion resistance and unusually high static load capacity. 440C steel and 60NiTi exhibit comparable Rockwell hardness and would be expected to exhibit similar sliding wear behavior using hardness based models. However, results show that under unlubricated sliding conditions, 60NiTi shows inferior wear properties than 440C steel. In this study, a series of indentation and single pass scratching experiments are conducted to elucidate the reasons behind this unexpected observation. Moreover, sliding wear tests carried out under moderate and extreme tensile stress conditions were used to identify sliding conditions under which these materials exhibit similar and dissimilar behavior. The results show that 440C steel exhibits more microscopic plasticity than 60NiTi, halting the propagation of generated tensile microcracks. In contrast, the intrinsic brittleness of 60NiTi leads to the formation and growth of microcracks between the shear bands causing subsequent wear particle generation. These lead to the occurrence of wear through more aggressive abrasion processes in 60NiTi than 440C steel. These findings help explain why 60NiTi performs well when lubricated. 60NiTi is expected to tolerate ～912?MPa tensile stress before yielding. Under good lubricated conditions where a perfect lubricating film is formed, friction induced tensile stresses fall below the tensile strength of 60NiTi and wear is prevented. However, inadequate lubrication combined with high contact stress leads to damage and wear.     

Prolonged drug release using PCL–TMZ nanofibers induce the apoptotic behavior of U87 glioma cells

In situ prolonged delivery of drugs at the site of tumor can be satisfactorily accelerated patient recovery. We compared the effect of temozolomide while incorporated by polycaprolactone nanofibers on the apoptotic behavior of U87 glioma cells. After biocompatibility evaluation of nanofibers by scanning electron microscope and 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide analysis, the apoptosis of U87 cells was evaluated using p53, Bcl2 and Bax genes expression. It was found that nanofiber-temozolomide group showed a greater ability to induce apoptosis as well as have a significantly diminished initial burst release of drug compared with other groups and have promising potential in treating cancer.     

Effect of baking in different ovens on the quality and structural characteristics of saltine crackers

The aim of the study was to evaluate the physical and microstructural characteristics of crackers baked in four different industrial baking ovens (indirect radiation-cyclotherm, indirect convection, hybrid and industrial tunnel-ITO). Indirect convection and cyclotherm ovens provide the highest (5685.43 ± 51 W m⁻²) and the lowest (4860 ± 38.87 W m⁻²) amount of heat flux, respectively. Despite the amount of heat flux, indirect convection led to crackers with the highest moisture (7.86% vs. 4.82% in clyclotherm) and specific volume, but the lowest hardness. Cyclotherm resulted in crackers with lower specific volume, surface area, porosity, smooth and regular surface. Conversely, the hybrid and ITO ovens showed closer heat flux, leading to crackers with similar moisture content, texture parameters, specific volume, browning and inner porosity. Overall results show the potential of baking using different ovens for modifying the quality parameters of the crackers.     

Improving the performance of novel polysulfone-based membrane via sulfonation method: Application to water desalination

High-performance polymers for water desalination were designed. A novel polysulfone was prepared via reaction between a new synthesized pyridine-based diol and bis(4-fluorophenyl) sulfone. Also a series of disulfonated copolymers with sulfonation content of 20–50 wt% were prepared to compare the hydrophilicity with the pristine polymer. The generated membranes were characterized by microscopic, mechanical, and thermal methods, and the influence of sulfonation degree on hydrophilicity, water flux, and salt rejection was followed. Water flux of sulfonated membranes was increased compare to pristine membrane as sulfonation increased, while the salt rejection decreased. Optimum application performance was obtained for membrane with 30 wt% sulfonation content. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48568.     

Embedded of Nanogel into Multi-responsive Hydrogel Nanocomposite for Anticancer Drug Delivery

Hydrogels, nanogels, and nanocomposites show increasing potential for application in drug delivery systems due to their good chemical and physical properties. Therefore, we were encouraged to combine them to produce a new compound with unique properties for drug release systems. To this aim, we first prepared poly [(N-isopropylacrylamide)-co-(2-dimethylamino ethyl methacrylate) nanogel by copolymerization processes and then added it into the solution of poly (2-dimethylamino ethyl methacrylate)] grafted onto salep. Through dropwise addition of mixed aqueous solution of iron salts into the prepared polymeric solution, a novel hydrogel nanocomposite with excellent pH, thermo, and magnetic responsive was fabricated. The obtained hydrogel nanocomposite were characterized by Fourier transform infrared spectroscopy, thermo gravimetric analysis, X-ray diffraction, scanning electron microscopy, vibrating sample magnetometer, and atomic force micrographs. The dependence of swelling properties of hydrogel nanocomposite on the temperature, pH, and magnetic field were investigated. The release behavior of doxorubicin hydrochloride (DOX) drug from DOX loaded into synthesized hydrogel nanocomposite was investigated at different pHs, temperatures, and magnetic field. In addition, the drug release behavior from obtained hydrogel nanocomposite was monitored via different kinetic models. Lastly, the toxicity of the DOX and DOX-loaded hydrogel nanocomposite were studied on MCF-7 cells at different times. These results suggested that the obtained hydrogel nanocomposite might have high potential applications in drug delivery systems.     

Synthesis and properties of a poly(sodium acrylate) bioadhesive nanocomposite

Poly(sodium acrylate) (PNaA) based nanocomposites were synthesized using different nanosilver loadings via redox solution polymerization at room temperature and under full exposure to the atmosphere. The nanocomposites exhibited increasing antibacterial activity with increased nanosilver content. Biocompatibility was determined using an MTT assay; no significant cytotoxicity was observed at the examined nanosilver loadings. Adhesion was measured using a tensile test and the stress versus strain curve showed an acceptable stress development in the model tissue using bioadhesive containing 2 wt% nanosilver. Introducing a second, more degradable polymer to the system as an interpenetrating polymer network enabled tuning the bioadhesive degradation rate.     

Characterization and the hydrogen storage capacity of titania-coated electrospun boron nitride nanofibers

In the present work, titania-coated (TiO₂) boron nitride nanofibers were produced by the electrospinning method, and the effect of heat treatment on the nanofibers was studied. Electrospinning method is often adopted for the synthesis of one-dimensional nanofibers due to high productivity, simplicity, and cost-effectiveness. In this study, boric oxide was deposited on co-electrospun polyacrylonitrile and TiO₂. TiO₂-coated boron nitride nanofibers, with a diameter of 100 nm, were obtained after heat treatment and nitridation. The effects of heat treatment on the morphology, surface area and hydrogen storage capacity were studied extensively. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM) showed long, bead-free nanofibers and the presence of TiO₂ nanoparticles on the nanofibers. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy depicted hexagonal structures of boron nitride. The hydrogen uptake capacities of the nanofibers were investigated by pressure composition isotherm (PCI) in the pressure range of 1–70 bar at room temperature.