Dependence of Semiconductor to Metal Transition of VO2(011)/NiO{100}/MgO{100}/TiN{100}/Si{100} Heterostructures on Thin Film Epitaxy and Nature of Strain

We have studied semiconductor to metal transition (SMT) characteristics of VO₂(011) thin films integrated epitaxially with Si(100) through NiO{001}/MgO{001}/TiN{001} buffer layers and correlated with the details of epitaxy and nature of residual stresses and strains across the VO₂/NiO interface. Thin film epitaxy at both room and elevated temperatures is studied in detail by electron microscopy and in situ high‐temperature X‐ray diffraction techniques. The epitaxial relationship across the interface between monoclinic VO₂ and NiO is determined to be (011)_VO2||{100}_NiO and [01]_VO2||[001]_NiO at room temperature. The epitaxial alignment at the temperature of growth where tetragonal VO₂ is stable is determined as: (110)_VO2||{100}_NiO and [001]_VO2||[100]_NiO. A cube‐on‐cube crystallographic alignment is established across the NiO{100}/MgO{100}/TiN{100}/Si{100} interfaces. The misfit strains across the VO₂/NiO interface at the growth temperature are calculated and the mechanism of strain relaxation is discussed. The out‐of‐plane orientation is found to be relaxed in both monoclinic and tetragonal states of VO₂. It is shown that a compressive strain of 31.65% along the [001] direction of tetragonal VO₂ is fully relaxed via matching of multiple domains. However, a small tensile misfit strain of about 5% along [10] direction cannot relax and remains in the lattice. This tensile residual strain leads to a compressive strain along [001] axis which, in turn, results in an SMT temperature slightly lower than that of freestanding strain‐free VO₂. SMT characteristics of VO₂(011) epilayers are assessed where an amplitude of near five orders of magnitude, and a hysteresis of less than 3.6 ^°C are obtained. This study introduces VO₂/NiO thin film heterostructure integrated with silicon as a promising candidate for multifunctional devices with novel characteristics where a combination of sensing, manipulation, and response functions is needed.     

Micro arc oxidation of nano-crystalline Ag-doped TiO2 semiconductors

Simple synthesis of silver doped TiO₂ nanostructured layers by micro arc oxidation process is reported for the first time. The layers consisted of anatase and rutile phases whose characteristic XRD-peaks shifted toward lower diffraction angles when compared to the pure micro arc oxidized TiO₂ layers. Silver-doping was confirmed by XPS technique. The anatase phase crystalline size was determined as 27.6 and 21.8 nm for the layers grown under the voltages of 350 and 500 V. Employing a UV-Vis spectrophotometer, a red shift in the absorption edge of the layers was observed when silver was incorporated into the titania lattice.     

Hydrothermal synthesis and characterization of TiO2 nanostructures using LiOH as a solvent

In the present study, we performed hydrothermal method as a simple and efficient route for the synthesis of rutile TiO₂ nanostructures in various concentrations of lithium hydroxide solutions. TiO₂ nanopowders with average sizes of 15 and 23 nm were prepared using 4 M and 7 M LiOH solutions. X-ray diffraction analysis (XRD), transmission electron microscope (FEG-STEM), scanning electron microscopy (SEM), and Brunauer–Emmet–Teller (BET) analyses were used in order to characterize the obtained products and comparison of the morphology of the powders obtained in different concentrations of LiOH solvent. It was shown that alkali solution concentration has affected the crystallinity, agglomeration ratio, particle size and specific surface area of the obtained rutile phases.     

A new cerium (III) ion selective electrode based on 2,9-dihydroxy-1,10-diphenoxy-4,7-dithia decane, a novel synthetic ligand

In the present study, a novel electrode based on 2,9-dihydroxy-1,10-diphenoxy-4,7-dithiadecane (DHDPDTD) that is selective to cerium (III) cations was evaluated electrochemically, and a Nerenstian slope (19.3 ± 1 mV decade⁻¹) over a concentration range of 1.0 × 10⁻⁸–1.0 × 10⁻¹ M and a detection limit of 2.1 × 10⁻⁹ M were observed. The proposed electrochemical sensor displayed a rapid response time of 10 s, improved selectivity towards Ce (III) cations in the presence of alkali, alkaline earth, transition and heavy metal cations, and could be used in a pH range of 5.0–8.0. Additionally, the proposed sensor was used as an indicator in the potentiometric titration of fluoride and the determination of F⁻ ions in real samples.     

Influence of multi-walled carbon nanotubes on creep behavior of adhesively bonded joints subjected to elevated temperatures

Polymeric materials are prone to creep loading. This paper is aimed to study the effect of multi-walled carbon nanotubes (MWCNTs) on creep behavior of adhesively bonded joints. Neat and MWCNTs-reinforced adhesively bonded joints were manufactured and tested under creep loading at elevated temperatures. Two MWCNT weight percentages of 0.1 and 0.3 were used for reinforcing the single lap joints (SLJs) and the joints were tested at different temperature and load levels. The results showed that 0.1 wt% of MWCNTs resulted maximum improvements in creep behavior of adhesive joints. Adding 0.1 wt% of MWCNTs into the adhesive layer caused maximum reductions of 57%, 60% and 47% in the steady-state creep rates of the joints tested at 30, 40 and 50°C, respectively. Furthermore, 0.1 wt% of MWCNTs resulted maximum reductions of 29%, 33% and 37% in the creep strains corresponding to a specific creep loading time and maximum reductions of 23%, 45% and 49% in the elastic strains corresponding to the time at which creep loading started.     

Fecal Microbiota Transplantation during and Post-COVID-19 Pandemic

COVID-19 is a major pandemic facing the world today, which has implications on current microbiome-based treatments such as fecal microbiota transplantation (FMT) used for recurrent Clostridioides difficile infections. The bidirectional relationship between the inhabitants of our gut, the gut microbiota, and COVID-19 pathogenesis, as well as the underlying mechanism involved, must be elucidated in order to increase FMT safety and efficacy. In this perspective, we discuss the crucial cross-talk between the gut microbiota and the lungs, known as the gut–lung axis, during COVID-19 infection, as well as the putative effect of these microorganisms and their functional activity (i.e., short chain fatty acids and bile acids) on FMT treatment. In addition, we highlight the urgent need to investigate the possible impact of COVID-19 on FMT safety and efficacy, as well as instilling stringent screening protocols of donors and recipients during COVID-19 and post-COVID-19 pandemic to produce a cohesive and optimized FMT treatment plan across all centers and in all countries across the globe.     

Selective uranyl cation detection by polymeric ion selective electrode based on benzo-15-crown-5

A uranyl cation selective electrode based on benzo-15-crown-5(B15C5) incorporated into a polyvinylchloride (PVC) membrane has been developed. The electrode was prepared by coating the surface of a graphite rod by a membrane containing dioctylphtalate (DOP) as plasticizer, B15C5 as an ionophore, carbon powder and polyvinylchloride (PVC) in tetrahydrofuran (THF). The best composition of the coated membrane (w/w%) was found to be: 4% ionophore, 20% plasticizer, 56% PVC and 20% carbon powder. The electrode exhibits a Nernstian slope (29.5 ± 2 mv) over the concentration range from 1.0 × 10^? 4 to 1.0 × 10^? 1 M. The detection limit of the electrode is 1.0 × 10^? 4 M. The effects of the pH and the possible interfering cations and anions were investigated and the optimized conditions for electrode were evaluated. The response time of the electrode is about 15 s and it can be used for more than 6 weeks without observing any divergence in potentiometric response. The electrode was applied as indicator electrode in potentiometric titrations.     

Structure,magnetic and transmission characteristics of the Co substituted Mg ferrites synthesized via a standard ceramic route

Co-Mg ferrites, ${\mathrm{Co}}_{\mathrm{x}}{\mathrm{Mg}}_{1?\mathrm{y}}{\mathrm{Fe}}_{2?\mathrm{z}}{\mathrm{O}}_4$ (x?=?0.0, 0.2, 0.4, 0.6, 0.8 and 1.0, 0?<?y?<?0.34 and 0?<?z?<?0.67), were synthesized via a standard ceramic route, and the structural, morphological, magnetic properties and transmission parameter of the samples were studied. The thermal behavior of the ground powder was characterized using a differential thermal analysis technique (DTA). The XRD patterns proved the formation of single phase Mg-ferrite in the samples with "x" contents varying from 0.0 to 0.8. The sample with x?=?1.0 showed two phases: a spinel Mg-ferrite and a secondary (Co,Mg)O phase. The lattice parameter and crystallite size of the samples increased remarkably by increasing the x content. The SEM images revealed that Co substitution in Mg ferrite at x?=?0.2 causes the particle growth, but their growth was not significant until x?=?0.8. For x?=?1.0, a remarkable particle growth was again observed. A maximum bulk density of 4.94?g/cm³ was obtained for x?=?0.8. Magnetic properties of the sintered samples showed an increase in coercive force up to 113?Oe by increasing Co substitution up to x?=?1.0. Saturation magnetization reached a maximum value of ~45.40?emu/g at x?=?0.8. Studying the microwave transmission behavior of the samples, using a vector network analyzer (VNA), indicated that by increasing Co, the transmission loss was reduced from $~$??15?dB for x?=?0.0 to less than ??10?dB for x?=?0.8 in the frequency range of 8–12?GHz.     

Incorporating supplier selection and order allocation into the vehicle routing and multi-cross-dock scheduling problem

In the vehicle routing problem with cross-docking (VRPCD), it is assumed that the selected suppliers and the quantity of the products purchased from each supplier are known. This paper presents an MILP model which incorporates supplier selection and order allocation into the VRPCD in a multi-cross-dock system minimising the total costs, including purchasing, transportation, cross-docking, inventory and early/tardy delivery penalty costs. The sensitivity of the model on the key parameters of the objective function is analysed and the supply decisions are evaluated when the coefficients of the distribution cost are changed. A two-stage solution algorithm (TSSA) is proposed and the results of the TSSA for small-sized instances are compared with the exact solutions. Finally, a large-sized real case of an urban freight transport is solved using the TSSA.