Synthesis of manganese (IV) oxide at activated carbon on reduced graphene oxide sheets via laser irradiation technique for organic binder-free electrodes in flexible supercapacitors

We report a novel, green, scalable technique to synthesize binder-free, high-purity conductive composite comprising activated carbon (AC), manganese dioxide nanorods (MnO₂), and reduced graphene oxide sheets (rGO) for flexible supercapacitors with outstanding electrochemical performance. UV pulsed laser irradiation of GO-based composite dispersion (AC/GO or MnO₂@AC/GO) in ethanol aqueous medium was used to induce a photocatalytic reduction of GO and simultaneous anchor AC particles or AC loaded MnO₂ nanorods (MnO₂@AC) on the reduced GO sheets (rGO) at room temperature and atmospheric pressure. rGO sheets serve as a large surface area, conductive binder to enhance the ion adsorption, electrical conductivity, and mechanical flexibility of supercapacitor electrodes. This laser-induced photocatalytic reduction method was used to prepare two different rGO-based colloidal composites AC/rGO (CG) and MnO₂@AC/rGO (MCG). The prepared rGO-based colloidal composites were used to fabricate symmetric supercapacitors (CG//CG and MCG//MCG) and asymmetric supercapacitors (MCG//CG) in which MCG is the positive electrode and CG is the negative one. All prepared rGO-based supercapacitors demonstrated significant improvement in their electrochemical performance compared with rGO-free AC based supercapacitors. The enhancement in the electrochemical properties of rGO-based supercapacitors could be attributed to the intrinsic characteristics of rGO, such as high surface area, excellent electrical conductivity, and super mechanical flexibility. Our approach is a one-step, scalable, cost-effective synthesis technique to produce all binder-free AC/rGO based composites for flexible energy-storage devices.     

An updated review of dietary isoflavones: Nutrition,processing, bioavailability and impacts on human health

Isoflavones (genistein, daidzein, and glycitein) are bioactive compounds with mildly estrogenic properties and often referred to as phytoestrogen. These are present in significant quantities (up to 4–5 mg·g^?1 on dry basis) in legumes mainly soybeans, green beans, mung beans. In grains (raw materials) they are present mostly as glycosides, which are poorly absorbed on consumption. Thus, soybeans are processed into various food products for digestibility, taste and bioavailability of nutrients and bioactives. Main processing steps include steaming, cooking, roasting, microbial fermentation that destroy protease inhibitors and also cleaves the glycoside bond to yield absorbable aglycone in the processed soy products, such as miso, natto, soy milk, tofu; and increase shelf lives. Processed soy food products have been an integral part of regular diets in many Asia–Pacific countries for centuries, e.g. China, Japan and Korea. However, in the last two decades, there have been concerted efforts to introduce soy products in western diets for their health benefits with some success. Isoflavones were hailed as magical natural component that attribute to prevent some major prevailing health concerns. Consumption of soy products have been linked to reduction in incidence or severity of chronic diseases such as cardiovascular, breast and prostate cancers, menopausal symptoms, bone loss, etc. Overall, consuming moderate amounts of traditionally prepared and minimally processed soy foods may offer modest health benefits while minimizing potential for any adverse health effects.     

Laser cutting of thick-section circular blanks: thermal stress prediction and microstructural analysis

Laser cutting of thick-section circular mild-steel blanks of 10 mm thickness is examined. Thermal and stress fields developed in the cutting zone are predicted using finite element method and the simulation conditions are selected in line with the experimental parameters. An experiment is carried out to assess the geometric features of the cut surfaces. The morphology of the cut sections are examined using optical and scanning electron microscopes and energy dispersive spectroscopy is carried out for elemental composition of the cut surface. It is found that laser cutting of thick steel blanks results in substantial conduction loss from the cutting zone, which results in high-temperature gradients and large stress levels in the cutting section. The cut edge features such as local dross attachment, striation patterns, and microcrack formation in the cut section are also examined.     

Synthesis and polymerization of 1,5-bis( N -carbazolyl)pentane with its structural and behavioral highlights

Carbazole, the well-known electron donor and hole-transporting organic light-emitting molecule was modified into 1,5-bis[N-carbazolyl]pentane (1,5-BNCP) by introducing the saturated pentane spacer. Such insertion fixed the certain space between growing polymer chains and demonstrated π–π stacking effect over its morphology and structure. Its contribution in improving the thermal stability and photosensitization was also investigated. The FT-IR and 1H NMR was used to characterize monomer. Morphology of subsequently polymerized material was seen under SEM. The position of polymerization and structural change were studied by FT-IR and XRD, respectively. Thermal study with reference to glass transition temperature and stability was analyzed by DSC and TGA. Optical properties of monomer and polymer were investigated by UV–visible and photoluminescent spectrophotometer. The material was found crystalline, thermally stable, highly photosensitized and white light emitter.     

On enhancing model‐based expectation maximization source separation in dynamic reverberant conditions using automatic Clifton effect

Source separation algorithms based on spatial cues generally face two major problems. The first one is their general performance degradation in reverberant environments and the second is their inability to differentiate closely located sources due to similarity of their spatial cues. The latter problem gets amplified in highly reverberant environments as reverberations have a distorting effect on spatial cues. In this paper, we have proposed a separation algorithm, in which inside an enclosure, the distortions due to reverberations in a spatial cue based source separation algorithm namely model‐based expectation‐maximization source separation and localization (MESSL) are minimized by using the Precedence effect. The Precedence effect acts as a gatekeeper which restricts the reverberations entering the separation system resulting in its improved separation performance. And this effect is automatically transformed into the Clifton effect to deal with the dynamic acoustic conditions. Our proposed algorithm has shown improved performance over MESSL in all kinds of reverberant conditions including closely located sources. On average, 22.55% improvement in SDR (signal to distortion ratio) and 15% in PESQ (perceptual evaluation of speech quality) is observed by using the Clifton effect to tackle dynamic reverberant conditions.     

A‐shaped wideband dielectric resonator antenna for wireless communication systems and its MIMO implementation

In this article, a new A‐shaped dielectric resonator antenna (DRA) excited by a conformal strip is proposed for wideband applications. The wide bandwidth is achieved by combining two adjacent modes that is, TM₁₀₁ and TM₁₀₃. The experimental results demonstrate that the proposed DRA offers an impedance bandwidth (for S11?10 dB) of 59.7% (3.24‐6.0 GHz), covering IEEE 802.11 and U‐NII bands. The antenna provides a fairly stable radiation pattern with the gain ranging from 5.29 to 7 dBi across the operating bandwidth. A dual‐element multiple‐input multiple‐output (MIMO) system is also realized using the proposed wideband DRA. The impedance bandwidth of the dual‐element MIMO antenna is 59.2% and 60.9% for Port1 and Port2, respectively and the isolation between the ports is better than 20 dB across the bandwidth. For Port1, the gain of the MIMO antenna ranging from 6.03 to 7.45 dBi is obtained across the bandwidth. Furthermore, the diversity performance of the MIMO antenna is found to be good with envelope correlation coefficient below 0.003 over the operating band. The proposed antenna could be the potential candidate for worldwide interoperability for microwave access (WiMAX), wireless local area network (WLAN) and lower European UWB frequency band (3.4‐5.0 GHz) applications.