Fabrication of Hollow Microspheres Using Single Step Electrospraying Process

In this study, a single step method for large scale fabrication of hollow microspheres with a narrow size distribution is presented. PolyBenzoThiadiazole (PolyBT), a conducting polymer, was electrosprayed at high voltage to obtain microspheres. Hollow spheres of size ranging from 4.1 to 7.3 µm were observed through scanning electron microscope images, without any chemical degradation as shown by FTIR studies. In addition, these microspheres demonstrated a change in optical and hydrophobic properties as exhibited by the UV-visible and contact angle measurements. Thus providing interesting opportunities for use in biomedical applications, sensors as well as optoelectronic devices

Benzimidazole-modified polyaniline micro-shells for electrochemical detection of cadmium in aqueous solution

Benzimidazole-functionalized polyaniline (BMPANI) was synthesized by interfacial poly­merization technique and used for electrochemical sensing of cadmium ions in an aqueous solution. The material was characterized for its structural and morphological features using Fourier-transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), and scanning electron microscopy (SEM). The BMPANI has a micro-shell structure produced from the self-assembly of the monomer units in solution before the polymerization reaction. The material was trialed for cadmium ion sensing using a BMPANI-modified carbon paste electrode (BMPANI-CPE). Electrochemical techniques, i.e., cyclic voltammetry (CV) and differential pulse anodic stripping voltammetry (DPASV), were performed to assess the sensing characteristics of the material. Various electrode preparation parameters, i.e., deposition potential, pH of deposition solution, and thickness of the active layer, were optimized to achieve the highest level of sensitivity. The selectivity towards cadmium ions, interference from other ions, as well as stability and reusability of the BMPANI-CPE, were also examined and found to be satisfactory

Functionalization of textile cotton fabric with reduced graphene oxide/MnO2/polyaniline based electrode for supercapacitor

In this work, a new cotton electrode has been synthesized by coating ternary materials of reduced graphene oxide (rGO), manganese dioxide (MnO2), and polyaniline (PANi) on textile cotton fabric. First, Graphene oxide was deposited on cotton fibers by a simple 'dip and dry' method and chemically reduced into rGO/cotton fabric. MnO2 nanoparticles were accumulated on rGO/cotton fabric by in situ chemical deposition method. PANi layer was coated on rGO/MnO2/cotton fabric by in situ oxidative polymerization technique. A thin PANi coating layer acts as a protective layer on rGO/MnO2/cotton fabric to restrain MnO2 nanoparticles and rGO from dissolution in H2SO4 acidic electrolyte. The specific surface area of cotton electrode was measured using the Brenauer-Emmett-Teller (BET) method. The cyclic voltammetry (CV) results show that the cotton electrode has good capacitive behavior. The ternary cotton electrode exhibits high specific capacitance values of 888 F g(-1) and 252 F g(-1) at a discharge current density of 1 A g(-1) and 25 A g(-1) in 1MH(2)SO(4) electrolyte solution. The high areal specific capacitance of 444 Fcm(-2) was achieved for as-fabricated electrode. Also, the cotton electrode retains around 70% of specific capacitance after 3000 cycles at charge-discharge current density of 15 A g(-1). The slow decrease in specific capacitance is observed with increased discharge current density which proves its excellent rate capability. These results of rGO/MnO2/PANi/cotton fabric electrode show that this can be an excellent electrode for supercapacitor in energy storage devices

Evaluating effectiveness of non-water based cleaning mechanisms for PV systems

Paper presented to the 3rd Southern African Solar Energy Conference, South Africa, 11-13 May, 2015.PV systems in tropical regions are gifted with ample sunshine, but also vulnerabilities to high cell temperatures and dust settlement. Dust related degradation is progressive and if left unattended, can severely inhibit by more than 40% the efficiency and output of the system. Current mechanisms of cleaning PV systems adopt large quantities of clean water, making the system unsustainable. The current study thereby investigates the effectiveness of non-water based cleaning mechanisms based on traditional palm-leaf brooms. These brooms were found to be more than 90% effective in comparison to water based cleaning. The reason for this effective cleaning has been further scrutinized based on micro-structure studies and dust adhering propertiesdc201

Gadolinium silicide (Gd5Si4) nanoparticles for tuneable broad band microwave absorption

Soft magnetic Gd5Si4 nanoparticles exhibit excellent microwave absorption in the Ku-band (12.4-18 GHz) when dispersed in poly (dimethyl siloxane), PDMS. The minimum experimentally recorded reflection loss (RL) of Gd5Si4-PDMS nanocomposite is −69 dB, with a large bandwidth for a single 6 mm-thick layer. The bandwidth can be further extended by using a novel design where 1 mm-thick layers of the nanocomposite are arranged into a modified pyramid-shaped absorber. Standard electromagnetic (EM) simulations confirm experimental results

Enhancement of microwave absorption bandwidth of polymer blend using ferromagnetic gadolinium silicide nanoparticles

Ferromagnetic gadolinium silicide (Gd5Si4) nanoparticles significantly enhance the microwave absorption bandwidth of a polymer blend (PVB-PEDOT:PSS). These materials are critically needed for various military and civilian applications such as X-band (8.2–12.4 GHz) and Ku-band (12.4–18 GHz) absorption. A single 1.2 mm thick layer of PVB-PEDOT:PSS-Gd5Si4 (PPGS) nanocomposite film shows the most promising bandwidth (8.2–18 GHz) with a minimum reflection loss of -14 dB. Mechanistically, dielectric loss (tan δe ≈2.4) and magnetic loss (tan δm ≈1.1) contributes more efficiently, and standard microwave simulation confirms the stored energy is predominant in PPGS nanocomposite which enhances the bandwidth

Self‐powered e‐Skin based on integrated flexible organic photovoltaics and transparent touch sensors

There is a growing interest in the large area, lightweight, low-power electronic skin (e-Skin), consisting of a multitude of sensors over conformable surfaces. The use of multifunctional sensors is always challenging, especially when their energy requirements are considered. Herein, the heterogeneous integration of custom-made flexible organic photovoltaic (OPV) cells is demonstrated with a large area touch sensor array. The OPV can offer power density of more than 0.32 μW cm−2 at 1500 lux, which is sufficient to meet the instantaneous demand of the array of touch sensors. In addition to energy harvesting, it is shown that the OPVs can perform shadow sensing for proximity and gesture recognition, which are crucial features needed in the e-Skin, particularly for safe interaction in the industrial domain. Along with pressure sensing (sensitivity of up to 0.26 kPa−1 in the range of 1–10 kPa) and spatial information, the touch sensors made of indium tin oxide and monolayer graphene have shown >70% transparency, which allow light to pass through them to reach the bottom OPV layer. With better resource management and space utilization, the presented stacked integration of transparent touch-sensing layer and OPVs can evolve into a futuristic energy-autonomous e-Skin that can “see” and “feel.

evidence of bipolar resistive switching memory in perovskite solar cell

In hybrid inorganic-organic perovskite solar cells a very stable bipolar resistive switching behavior in the dark current-voltage characteristics at low-voltages has been observed. The possible use of the solar cell as an electrical memory with a moderate on-off contrast but very good stability over a prolonged time has been suggested. The reversible behavior and the long dynamics during the write/erase processes indicate that the physical mechanism behind the switching is related to polarization effects. A detailed analysis of the charge carrier trapping/detrapping, transport, and recombination mechanisms has been performed by taking the ion migration and the consequent charge carrier accumulation within the device into account. The charge transport during the write operation can be described by space-charge-limited conduction process. The formation and subsequent interruption of conducting pathways due to ion migration have been identified as the main cause of the resistive switching within the perovskite material. The strong interaction between the ion movement and the electron transport enables the operation of the perovskite solar cell also as a non-volatile memory

Evidence-based assessment of antiosteoporotic activity of petroleum-ether extract of Cissus quadrangularis Linn. on ovariectomy-induced osteoporosis

The increasing incidence of postmenopausal osteoporosis and its related fractures have become global health issues in the recent days. Postmenopausal osteoporosis is the most frequent metabolic bone disease; it is characterized by a rapid loss of mineralized bone tissue. Hormone replacement therapy has proven efficacious in preventing bone loss but not desirable to many women due to its side-effects. Therefore we are in need to search the natural compounds for a treatment of postmenopausal symptoms in women with no toxic effects. In the present study, we have evaluated the effect of petroleum-ether extract of Cissus quadrangularis Linn. (CQ), a plant used in folk medicine, on an osteoporotic rat model developed by ovariectomy. In this experiment, healthy female Wistar rats were divided into four groups of six animals each. Group 1 was sham operated. All the remaining groups were ovariectomized. Group 2 was fed with an equivolume of saline and served as ovariectomized control (OVX). Groups 3 and 4 were orally treated with raloxifene (5.4 mg/kg) and petroleum-ether extract of CQ (500 mg/kg), respectively, for 3 months. The findings were assessed on the basis of animal weight, morphology of femur, and histochemical localization of alkaline phosphatase (ALP) (an osteoblastic marker) and tartrate-resistant acid phosphatase (TRAP) (an osteoclastic marker) in upper end of femur. The study revealed for the first time that the petroleum-ether extract of CQ reduced bone loss, as evidenced by the weight gain in femur, and also reduced the osteoclastic activity there by facilitating bone formation when compared to the OVX group. The osteoclastic activity was confirmed by TRAP staining, and the bone formation was assessed by ALP staining in the femur sections. The color intensity of TRAP and ALP enzymes from the images were evaluated by image analysis software developed locally. The effect of CQ was found to be effective on both enzymes, and it might be a potential candidate for prevention and treatment of postmenopausal osteoporosis. The biological activity of CQ on bone may be attributed to the phytogenic steroids present in it