Design of dual‐band microstrip patch antenna with right‐angle triangular aperture slot for energy transfer application

This work focusing on the dual‐band antenna design with rectifying circuit for energy transfer system technology for enhancement gain performance. The air gap technique is applied on this microstrip antenna design work to enhance the antenna gain. The work begins with designing and analyzing the antenna via the CST Microwave Studio software. After validation on acceptable performance in simulation side is obtained, the return loss, S₁₁ of the antenna is measured using vector network analyzer equipment. The rectifier circuit is used to convert the captured signal to DC voltage. This projected dual‐band antenna has successfully accomplished the target on return loss of ?44.707 dB and ?32.163 dB at dual resonant frequencies for 1.8 GHz and 2.4 GHz, respectively. This proposed antenna design benefits in low cost fabrication and has achieved high gain of 6.31 dBi and 7.82 dBi for dual‐band functioning frequencies.     

Potential of sodium alginate/titanium oxide biomembrane nanocomposite in DMFC application

A proton exchange membrane was synthesized consuming a sodium alginate biopolymer as the matrix and titanium oxide as the nanofiller. The titanium oxide content varied from 5 to 25 wt%. The biomembrane nanocomposite performs better than the pristine sodium alginate membrane based on liquid uptake, methanol permeability, proton conductivity, ion exchange capacity, and oxidative stability outcomes. The unique properties of sodium alginate and titanium oxide lead to outstanding interconnections, thus producing new materials with great characteristics and enhanced performance. The highest proton conductivity achieved in this study is 17.3 × 10^‐3 S cm^‐1, which performed by SAT5 (25 wt%) membranes at 70°C. An optimal content of titanium oxide enhances the conductivity and methanol permeability of the membrane. Additionally, the hydrophilicity of pure sodium alginate is greatly reduced and achieves a good liquid uptake capacity and swelling ratio. The characteristics of the SA/TiO₂ biomembrane nanocomposite were determined with field emission scanning electron microscope, Fourier transform infrared, X‐ray diffraction, thermal gravimetric analysis/differential scanning calorimetry, and mechanical strength analysis.     

The Effect of Polar Head and Chain Length on the Physicochemical Properties of Micellization and Adsorption of Amino Alcohol-Based Surfactants

In this work, we have synthesized a series of quaternary ammonium from amino alcohols and n-bromoalkanes. The compounds are referred to as C_nEtOH, C_nPrOH, and C_niPrOH (where n = 12 and 14 carbons, EtOH = ethanol, PrOH = propanol, iPrOH = iso-propanol). Their structures were checked using the usual spectroscopic methods [¹H, ¹³C nuclear magnetic resonance (NMR) and infrared (IR)]. Their physicochemical properties in aqueous solution were studied using conductivity, surface tension, and ultra violet (UV)–visible absorption spectroscopy measurements. This study was conducted to show the effect of the linear hydrophobic chain and the location of the OH polar group with respect to the N⁺ quaternary ammonium on the physicochemical properties of the surfactants. The comparison between the physicochemical properties of the surfactants studied shows a distinct effect of the position of the OH group on the critical micelle concentration (CMC), the ionization degree (α), the area occupied at the interface (A_min), the free energy of adsorption (), and the free energy of micellization (). The intermolecular interaction between the synthetic surfactants and the methyl orange (OM) dye is related to the degree of hydration of the micelle, proven by the hypsochromic displacement of OM wavelength (λ_max) and ionization (α) of the micelles. The CMC, the degree of ionization, and the degree of hydration of the micelle follow the same trend.     

n-Hexane hydroisomerization over Zr-modified bicontinuous lamellar silica mordenite supported Pt as highly selective catalyst: Molecular hydrogen generated protonic acid sites and optimization

Zr-modified bicontinuous lamellar silica mordenite supported Pt catalysts were synthesized using the zirconyl chloride oxahydrate as the precursor for Zr species by the incipient wetness impregnation method. The influence of zirconium loading on the properties of Zr-modified HM@KCC-1 catalysts for n-hexane isomerization were studied. The results of XRD and lattice structure from IR study indicated that increasing zirconium loading did not change the properties of catalysts. The IR study with pre-adsorbed 2,6-dimethylpyridine as a probe molecule affirmed that increasing zirconium loading could increase the Lewis acid sites. The generation of protonic acid sites which were active in n-hexane hydroisomerization was mainly from molecular hydrogen through a hydrogen spill-over mechanism as established by in situ-IR study. The results for the catalytic testing indicated that PtZr/HM@KCC-1 catalyst was highly selective in n-hexane hydroisomerization due to abundant permanent Lewis acid sites for its promotive effect in the generation of protonic acid sites. However, the incorporation of excessive zirconium amount up to 10 wt percent loading led to a decline in the amount of protonic acid sites generated, thus reduced the hydroisomerization performance in the process. The optimum conditions for hydroisomerization of n-hexane over Pt5Zr/HM@KCC-1 were reaction temperature of 293 °C, treatment temperature of 474 °C and F/W of 502 mL/g.min with the predicted value for isomer yield of 83.9%.     

Evaluation of Quaternized polyvinyl alcohol/graphene oxide-based membrane towards improving the performance of air-breathing passive direct methanol fuel cells

Graphene oxide (GO) nanosheets are introduced to a Quaternized polyvinyl alcohol (QPVA) polymer matrix to obtain an anion exchange membranes (AEMs) for application of fuel cells. QPVA/GO nanocomposite membranes provide desirable properties such as low fuel uptake and permeability, excellent ionic conductivity, and cell performance, all of which are favorable for AEMs based on our previous works. Passive direct methanol fuel cells (DMFCs) are recognized as suitable technologies for use in portable devices. Nevertheless, the commercialization of DMFCs remains restricted due to a number of issues related to the conventional membrane; one of these issues is high fuel crossover problems due to high fuel uptake and permeability of Nafion membrane. This study aimed to expand the potential applications of QPVA/GO nanocomposite membranes in air-breathing passive DMFCs. The ionic conductivity, methanol uptakes (MUs), and permeabilities of self-synthesis QPVA/GO nanocomposites are examined to evaluate the ability to operate in methanol atmosphere. At 30°C, the ionic conductivity of the membranes reached 1.74 × 10⁻² S cm⁻¹. The MUs and permeabilities were as low as 35% and 7.6 × 10⁻⁷ cm² s⁻¹, respectively. The performance of air-breathing passive DMFCs bearing QPVA/GO nanocomposite membrane is much higher compared to conventional membranes. The maximum power density of air-breathing passive DMFCs was achieved 27.2 mW cm⁻² under the optimum condition of 2 M methanol + 4 M KOH at 70°C. Single-cells could be sustained for 1000 hours. This article is the first to optimize and highlight the performance air-breathing passive DMFCs by using a QPVA-based membrane.     

Performance of quaternized poly(vinyl alcohol)-based electrolyte membrane in passive alkaline DEFCs application: RSM optimization approach

Direct ethanol fuel cells (DEFCs) have emerged as potential tools for producing sustainable energy for portable devices due to their high energy density and their safe and nontoxic fuel source. However, the main problem of DEFCs is the sluggish oxidation of ethanol and fuel crossover from the anode side to the cathode side. Nafion membranes are commonly used as the electrolyte membrane in DEFCs, but they have a high production cost and high ethanol permeability. Thus, this work studies the performance of an alternative electrolyte membrane that is based on a quaternized poly(vinyl alcohol) (QPVA) polymer in passive alkaline DEFCs. The composition of the QPVA-based membranes was optimized with potassium hydroxide (KOH) as an ion charge carrier and by the inorganic filler graphene oxide (GO). The membrane properties were influenced by KOH and GO. The effect of these two parameters on the performance of the QPVA-based membranes was investigated for its ion-exchange capacity and ionic conductivity and selectivity using the response surface methodology to optimize the membrane composition. The QPVA-based membranes were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and field emission scanning electron microscope. The membrane properties were influenced by KOH concentration doping and GO filler loading, which affect the membrane selectivity and, consequently, the overall performance of the passive alkaline DEFCs. Finally, the maximum power density of the passive DEFCs was improved from 5.8 to 11.3 W cm⁻² at 30 °C, 13.7 mW cm⁻² at 60 °C, and 19.3 mW cm⁻² at 90 °C, respectively, in ambient air. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47526.     

Formation and analysis of stack cracks in a pipeline steel

Extensive cracking of the type known as stack cracking was demonstrated in a cathodically charged X65 microalloyed pipeline steel containing a weldment. It is shown that the formation and propagation of rolling-plane cracks, which constitute the primary stages of the stack cracking, is due to local concentration of hydrogen gas pressure and a lowering of the cohesive strength of a number of interfaces by hydrogen. The characteristic S-shape of individual cracks which occurred during the linking up of cracks was attributed to stress interactions at crack tips and cleavage cracking normal to the rolling plane. An explanation of hydrogen embrittlement fracture is given in terms of electronic state modifications of the steel, including charge polarization.     

Gamma irradiation of (styrene butadiene rubber)/(devulcanized waste rubber) blends modified by organoclay

In this study, the physicomechanical properties and morphology evolution of irradiated (styrene butadiene rubber)/(devulcanized waste rubber)/(organically modified montmorillonite) nanocomposites were realized. The improvement in the physicomechanical properties provides a possible mechanism on how organically modified montmorillonite influences the general properties of irradiated nanocomposites. X‐ray diffraction data illustrated that there is an increase in the basal spacing of sodium montmorillonite clay due to modification and/or polymer intercalation. The results of mechanical properties showed that the as‐prepared nanocomposites have superior irradiation‐resistant properties to the (styrene butadiene rubber)/(devulcanized waste rubber) blend. J. VINYL ADDIT. TECHNOL., 24:50–57, 2018. © 2015 Society of Plastics Engineers