Humidity sensing and electrical properties of polyaniline/cobalt oxide composites

Polyaniline/cobalt oxide composites were synthesized by an in situ chemical polymerization method with ammonium persulfate as an oxidizing agent. This was a single‐step polymerization process for the direct synthesis of the emeraldine salt phase of the polymer. The polymers were characterized with X‐ray diffraction, scanning electron microscopy, and Fourier transform infrared spectral analysis. The formation of mixed phases of the polymer together with the conducting emeraldine salt phase was confirmed by spectroscopic techniques. High‐temperature conductivity measurements showed thermally activated behavior. A change in the resistance was observed with respect to the relative humidity when the pellets were exposed to a wide humidity range of 10–95%. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 653–658, 2007     

A decision-making approach for energy efficiency improvement in municipal water pumps during water scarcity scenario

Cities in Sub-Saharan Africa suffer from widespread disparities in water supply due to depletion in groundwater and global-warming-induced changes in weather patterns. The offset of water head from the design considerations of water pumping systems has increased energy requirements leading to worsening of the situation with respect to availability of energy and water. Consequently, highly capitalized water supply schemes, which have been designed to meet the demand, are underutilized leading to operational inefficiencies. Robust empirical equations can help detect inefficiencies in water pumping systems, and this paper discusses the equations which were developed by analysing data obtained from various water supply utilities facing water scarcity. These equations provide cost-benefit analysis for decision making in water utilities and can bring about energy efficiency in municipal pumping operations.     

Predicting the customer’s opinion on amazon products using selective memory architecture-based convolutional neural network

The Journal of Supercomputing - Opinion mining and sentiment analysis are useful to extract subjective information out of bulk text documents. Predicting the customer’s opinion on amazon...     

Frequency‐dependent conductivity and dielectric permittivity of polyaniline/CeO2 composites

The PANI/CeO₂ composites were synthesized using in situ deposition technique by placing fine graded CeO₂ in polymerization mixture of aniline. This is the single step polymerization process for the direct synthesis of emeraldine salt phase of polymer. Low frequency dielectric studies were carried out on pressed pellets of PANI/CeO₂ with various concentrations of cerium oxide (10, 20, 30, 40, and 50 wt % of CeO₂ in PANI). The results are interpreted in terms of polarons and bipolarons, which are responsible for the dielectric relaxation mechanism and frequency dependence of conductivity. It is found that a.c. measurements at room temperature may well serve as a parallel way to the time consuming d.c. conductivity versus temperature technique, to detect the thermal degradation of the transport properties in conducting polymers. It is observed that the charge motion via creation/annihilation of polarons and bipolarons increases as the weight percentage of the composite is increased. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1403–1405, 2006     

Biobanked Glioblastoma Patient-Derived Organoids as a Precision Medicine Model to Study Inhibition of Invasion

Glioblastoma (GBM) is highly resistant to treatment and invasion into the surrounding brain is a cancer hallmark that leads to recurrence despite surgical resection. With the emergence of precision medicine, patient-derived 3D systems are considered potentially robust GBM preclinical models. In this study, we screened a library of 22 anti-invasive compounds (i.e., NF-kB, GSK-3-B, COX-2, and tubulin inhibitors) using glioblastoma U-251 MG cell spheroids. We evaluated toxicity and invasion inhibition using a 3D Matrigel invasion assay. We next selected three compounds that inhibited invasion and screened them in patient-derived glioblastoma organoids (GBOs). We developed a platform using available macros for FIJI/ImageJ to quantify invasion from the outer margin of organoids. Our data demonstrated that a high-throughput invasion screening can be done using both an established cell line and patient-derived 3D model systems. Tubulin inhibitor compounds had the best efficacy with U-251 MG cells, however, in ex vivo patient organoids the results were highly variable. Our results indicate that the efficacy of compounds is highly related to patient intra and inter-tumor heterogeneity. These results indicate that such models can be used to evaluate personal oncology therapeutic strategies.     

Spectroscopic and electrical properties of polyaniline/CeO2 composites and their application as humidity sensor

Polyaniline/CeO₂ composites were synthesized by in situ chemical polymerization method using ammonium persulphate as an oxidizing agent. This is the single step polymerization process for the direct synthesis of emeraldine salt phase of polymer. The polymers were characterized by using FTIR spectral analysis, SEM, and XRD studies. Formation of conducting emeraldine salt phase is confirmed by spectroscopic techniques. High temperature conductivity measurements show “thermal activated behavior.” The change in resistance with respect to percentage relative humidity (% RH) is observed, when the pressed pellets of the polymer were exposed to the broad range of humidity (humidity ranging between 10 and 95% RH). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:5533–5537, 2006     

Synthesis,transport and dielectric properties of polyaniline/Co<Subscript>3</Subscript>O<Subscript>4</Subscript> composites

Conducting polyaniline/cobaltous oxide composites have been synthesized using in situ deposition technique by placing fine graded/cobaltous oxide in polymerization mixture of aniline. The a.c. conductivity and dielectric properties are studied by sandwiching the pellets of these composites between the silver electrodes. It is observed that the values of conductivities increase up to 30 wt% of cobaltous oxide in polyaniline and decrease thereafter. Initial increment in conductivity is due to extended chain length of polyaniline where polarons possess sufficient energy to hop between favourable sites. Beyond 30 wt% of cobaltous oxide in polyaniline, blocking of charge carriers takes place reducing the conductivity values. It can be noted that the value of dielectric constant increases up to 10 wt% of cobaltous oxide. Thereafter, it decreases up to 30 wt% of cobaltous oxide and again increases up to 40 wt% of cobaltous oxide and decreases thereafter. The observed behaviour is attributed to the variation of a.c. conductivity. And it is observed that the dielectric loss increases up to 10 wt% of cobaltous oxide in polyaniline, decreases to a lower value of 20 wt% of cobaltous oxide and increases to 35 wt% and thereafter decreases. These values go in accordance with the values of dielectric constant. The results obtained for these composites are of greater scientific and technological importance.     

Potential of aflatoxin B1 production by Aspergillus flavus strains on commercially important food grains

In this study, we investigated the potential of aflatoxin B₁ (AFB1) production by five Aspergillus flavus strains previously isolated from sorghum grains on cereals (barley, maize, rice, wheat and sorghum), oilseeds (peanuts and sesame) and pulses (greengram and horsegram). Five strains of A. flavus were inoculated on all food grains and incubated at 25 °C for 7 days; AFB1 was extracted and estimated by enzyme‐linked immunosorbent assay. All A. flavus strains produced AFB1 on all food grains ranging from 245.4 to 15 645.2 μg kg^?1. Of the five strains tested, strain Af 003 produced the highest amount of AFB1 on all commodities ranging from 2245.2 to 15 645.2 μg kg^?1. Comparatively, the AFB1 accumulation was high on rice grains ranging from 3125.2 to 15 645.2 μg kg^?1, followed by peanuts ranging from 2206.2 to 12 466.5 μg kg^?1. Less AFB1 accumulation was observed in greengram and sesame seeds ranging from 645.8 to 2245.2 and 245.4 to 2890.6 μg kg^?1, respectively. Our results showed that all food grains tested are susceptible to A. flavus growth and subsequent AFB1 production.     

Electrochromic switching and nanoscale electrical properties of a poly(5-cyano indole)-poly(3,4-ethylenedioxypyrrole) device with a free standing ionic liquid electrolyte

Poly(5-cyano indole) or PCIND and poly(3,4-ethylenedioxy pyrrole) or PEDOP films have been electro-synthesized for the first time in a hydrophobic ionic liquid: trihexyl(tetradecyl)phosphonium tris(pentafluoroethyl)trifluorophosphate. PCIND, is an anodically coloring electrochrome, and exhibited a reversible switching between a transmissive yellow and a saturated green hue, with an absorption maximum at 650 nm in the fully oxidized state. Conducting atomic force microscopy studies revealed the PCIND film to be composed of an ensemble of segregated high current islands with a nanoscale electronic conductivity of 0.1 S cm⁻¹ and a band gap of 1.41 eV. The cathodically coloring PEDOP film comprised of uniformly distributed and inter-connected high current carrying domains with a band gap of 1.82 eV and a conductivity of 5.4 S cm⁻¹. Prototype electrochromic devices were fabricated using PEDOP and PCIND as cathode and anode with a thermally stable ionic liquid based, free standing polymeric gel film with a high ionic conductivity of 1.19 × 10⁻³ S cm⁻¹ as the electrolyte. The device showed large coloration efficiencies of 480 and 796 cm² C⁻¹ at visible and NIR wavelengths of 475 and 1100 nm respectively which far exceeded the coloration efficiencies of the individual electrochromes, thereby demonstrating the synergy between the two colorants. The performance attributes of the device, which switched reversibly between red, green and blue hues, are an outcome of an interplay between the high nanolevel electron conduction capabilities (enable fast charge transport) and high ion storage capacities (increase optical contrast as more number of electrochemically addressable sites are accessed by the electrolyte ions) of the PEDOP and PCIND films. Our studies demonstrate the applicability of PCIND films as anodic electrochromes in energy efficient windows.