Thermal buckling analysis of laminated composite beams using hyperbolic refined shear deformation theory

In this article, thermal buckling of laminated composite beams, based on hyperbolic refined shear deformation theory, presented for the first time, is formulated using the principle of minimum total potential energy. Navier’s analytical solution is derived to analytically solve the differential equations and the thermal critical buckling is presented in closed-form solution. The effects of temperature distribution, length to thickness ratio, modulus ratio, and thermal expansion coefficient ratio on thermal buckling of isotropic, orthotropic and laminated composite beams are investigated. The accuracy of the numerical model is verified by comparison with the available results in the literature.     

Ge-doped ZnO nanorods grown on FTO for photoelectrochemical water splitting with exceptional photoconversion efficiency

In this study, a considerable effort has been devoted for the synthesis of Ge-doped ZnO nanorods on FTO as an efficient and robust photoanode material for solar water splitting. A unique, optimized, and ultra-rapid fabrication method to produce uniform nanorods (30–70 nm in diameter) has been demonstrated using radio frequency sputtering followed by electrochemical anodization. The effect of Ge doping on the conductivity, charge carrier concentration, optical, and photoelectrochemical properties of ZnO was investigated using scanning electron microscope (SEM), glancing angle X-ray diffraction (GAXRD), UV–Vis spectrometer, and Mott Schottky analysis. Glancing angle XRD confirmed the presence of wurtzite structure with a preferable orientation around (101) plane, which is of particular interest for many applications. As evidenced by the photoelectrochemical and transient photocurrent measurements, the fabricated Ge-doped ZnO nanorods exhibited enhanced photocurrent (12 mA/cm²) with an exceptional open circuit voltage of ?1.07 V_SCE (?0.416 V_RHE) under AM1.5G illumination, compared to the undoped ZnO based-photoanodes. Moreover, the Ge-doped ZnO nanorods showed unprecedented photoconversion efficiency of 3.6% under AM1.5G illumination. Therefore, the fabricated Ge-doped ZnO nanorods could be a promising conductive photoanode for water splitting.     

Synthesis and characterization of partially crystalline nanosized ZSM-5 zeolites

Partially crystalline nanosize ZSM-5 with high surface area (678 m²/g) was synthesized successfully without using organic template by a two-step temperature process. Aluminum nitrate was used as aluminum source for the first time to synthesize ZSM-5 materials. The presence of MFI structure of the materials was analyzed by XRD, FTIR, Raman spectroscopy and TEM techniques. Addition of commercial HZSM-5 as a seeding agent to the reactants resulted an increase in crystallinity of the ZSM-5 sample and subsequent decrease in specific surface area. The partially crystalline samples exhibited low microporosity and remarkably high meso/macropore volume with pore diameters around 30 nm.     

Sequential Template Decomposition to Adjust the Performance of Imperfect Zeolite BEA Membranes

Zeolite membranes offer superior thermal, chemical, and mechanical stability compared to polymeric membranes. However, it is still a challenge to prepare completely defect‐free membranes without any intercrystalline voids, which is necessary for gas separation processes. In this study zeolite beta (*BEA) membranes on stainless‐steel supports were prepared by applying the multiple in situ crystallization technique. The membranes were used as a model system to systematically study the decomposition of the organic structure directing agent tetraethylammoniumhydroxide (TEA‐OH). It was evaluated if the organic decomposition products of TEA‐OH can be used for enhancing the membranes selectivity. Post‐treatment experiments have been carried out to adjust surface properties and pore size dimensions in the zeolitic membrane layer. The results show that membranes calcined at lower temperatures exhibit a higher gas selectivity.     

Synthesis,characterization and electrochemical performance of Sn3F3PO4 anode material for lithium-ion batteries

Tin fluorophosphate (Sn₃F₃PO₄) powder was synthesized via a microemulsion route. Physical properties of the synthesized material were investigated by means of X-ray powder diffractometry (XRD) and field emission scanning electron microscopy (FE-SEM). The investigation showed that the synthesized powder was crystalline Sn₃F₃PO₄ with needle-like morphology with a thickness of 300–500 nm and length of 5–10 μm. The electrochemical performance of the synthesized powder as a negative electrode for Li-ion batteries was studied. The results showed that the synthesized Sm₃F₃PO₄ possessed an initial discharge capacity of 1370 mAh g^?1 and charge capacity of 968 mAh g^?1 in a potential range of 0.005–3 V. In addition, the material showed capacity retention of 70.8% after 30 cycles at a constant current density of 100 mA g^?1.     

Dehydration of potato slices following brief dipping in osmotic solutions: Effect of conditions and understanding the mechanism of water loss

A novel variant of osmotic dehydration, named here as postdipping dehydration—where a material is dipped in a salt or sugar solution for a very short time followed by simple exposure to ambient conditions was explored with the aim of lowering water content of potato slices but at the same time not gain a high level of sugar/salt. The rate of water loss, which was rapid initially, was found to approach equilibrium. This article also explored whether the water loss process could subsequently be kick started once again, by employing a multistage process, where each stage consisted of osmotic solution dipping followed by ambient holding of the potato slices that had reached equilibrium in the earlier stage. Water loss values comparable to conventional osmotic dehydration could be achieved thus, but with significantly lower overall solid gain (<50%)—which can potentially yield a significantly healthy product option.     

About the influence of temperature and environmental relative humidity on the longitudinal and transverse mechanical properties of elementary alfa fibers

Composites reinforced with plant-based fibers present a high potential for valorization in new industrial applications due to their good specific mechanical characteristics, renewability, and recyclability. In order to accelerate their wide industry adoption, it is critical to assess their behavior and durability in heat and humid environments. This article aims at investigating the effects of temperature and relative humidity (RH) on the longitudinal and transverse mechanical properties of the lignocellulosic fibers extracted from alfa plant (Stipa tenacissima L). For this purpose, tensile and nanoindentation tests were performed on elementary alfa fibers subjected to a thermal cycle of 200°C. The fibers were held at various periods of 15, 30, 60 and 120 min. The test results showed that the longitudinal and transverse Young's moduli are moderately affected by short thermal cycles having duration of 15–30 min. However, for longer thermal cycle (i.e., 2 hr), a degradation of 21% for the transverse modulus was recorded. This degradation doubled for the longitudinal modulus (43 vs. 21%). A similar trend was observed for the breaking strength. This study also showed that the RH strongly affects the mechanical performances of alfa fibers.     

Photovoltaic enhancement of nanostructured boron-doped rutile phase TiO2 nanorods via facile hydrothermal method

Journal of Materials Science: Materials in Electronics - Several doping processes are being investigated for the enhancement and efficient utilization of TiO2 properties with increased focus on the...     

Dealing with feature interactions for prismatic parts in STEP-NC

Determining the precedence of machining features is a critical issue in feature-based process planning. It becomes more complex when geometric interaction occurs between machining features. STEP-NC, the extension of STEP (ISO 10303) standard developed for CNC controllers, is a feature-based data model. It represents all the geometric and topological product data minus feature interactions. In this paper, machining precedence of interactive and non-interactive STEP-NC features is discussed. Local and global precedence of machining features are defined on the basis of geometric constraints, such as geometric interaction of features and feature approach face and technological constraint such as access direction of the cutting tool. A software tool has been developed to visualize the STEP-NC part model and to generate the graphs of feature interaction and feature precedence. The output can be then used to augment the STEP-NC data in order to generate the optimal sequence of operations.