Electrical,thermal and microwave shielding properties of printable silver nanowires

Silver nanowires find use in a myriad of applications, including communication systems, sensors, medical devices and electrical equipment. Temperature-dependent electrical and thermal properties of chemically derived silver nanowires are rarely explored. In the present work, seed-mediated synthesis of silver nanowires has been carried out, and their electrical and thermal conductivity at 300 K is found to be 1.848?×?10⁷ S/m and 64.8 W/mK, respectively. A screen-printable ink of silver nanowires is formulated and printed on low-cost and widely used substrates like paper and cotton fabrics. Flexible printed electrodes could be made possible with uniform printed structures obtained in cotton fabric and paper substrate. The printed pattern exhibited sheet resistance of 0.7 Ω/sq. Screen-printed silver nanowires on paper show shielding efficiency of 99.9% in X band, which promotes them as excellent candidates in fabricating lightweight electronic devices by a one-step printing process.

Graphical abstract

     

Single-Component CMOS-Like Logic using Diketopyrrolopyrrole-Based Ambipolar Organic Electrochemical Transistors

Complementary circuits based on organic electrochemical transistors (OECTs) are attractive for the development of inexpensive and disposable point-of-care bioelectronic devices. Ambipolar OECTs, which employ a single channel material, could decrease the fabrication complexity and manufacturing costs of such circuits. An ideal channel material for ambipolar OECTs should be electrochemically stable in aqueous environments, afford facile ion insertion for both cations and anions, and also facilitate high and balanced electron and hole transport. In this study, triethylene glycol functionalized diketopyrrolopyrrole (DPP)-based polymer is proposed for the development of ambipolar OECTs. It is shown that DPP-based OECTs have a high and comparable figure of merit for both n- and p-type operations. Logic NOT, NAND, and NOR operations with corresponding complementary circuits constructed from identical DPP-based OECT devices are demonstrated. This study is an important step toward the development of sophisticated complementary metal–oxide–semiconductor-like logic circuits using single-component OECTs.     

Rare‐earth‐doped SiO2‐CaF2 glass ceramic nano‐particle with upconversion properties

Rare‐earth‐doped upconversion nano‐phosphor shows new possibilities in the field of bioimaging because of its unique properties like higher penetration depth, low signal to noise ratio (SNR), good photo stability, and zero auto fluorescence. The oxyfluoride glass system is the combination of both fluoride and oxide where fluoride host offers high optical transparency due to low phonon energy and oxide network offers high physical stability. Thus, in the present work, an attempt has been made to synthesize 1 mol% Er³⁺ doped SiO₂‐CaF₂ glass ceramic nano‐particles through sol‐gel route. The synthesized glass ceramic particles were heat treated at 4 different temperatures starting from 600°C to 900°C.The X‐ray diffraction (XRD) analysis and Transmission electron microscopy (TEM) analysis confirmed the formation of CaF₂ nano‐crystals in the matrix which is 20‐30 nm in size. The vibrational spectroscopic analysis of the glass ceramics sample has been investigated by Fourier transform infrared (FTIR) spectroscopy. The UV‐Visible‐NIR spectroscopy analysis was carried out to analyze the absorption intensity in the near infrared region. Upon 980 nm excitation, the sample shows red emission corresponds to ⁴F_9/2→⁴I_15/2 energy level transition. The prepared nano‐particles showed excellent biocompatibility when tasted on MG‐63 osteoblast cells.     

Overview on mitigation of acrylamide in starchy fried and baked foods

Acrylamide in fried and baked foods has the potential to cause toxic effects in animals and humans. A major challenge lies in developing an effective strategy for acrylamide mitigation in foods without altering its basic properties. Food scientists around the world have developed various methods to mitigate the presence of acrylamide in fried food products. Mitigation techniques using additives such as salts, amino acids, cations and organic acids along with blanching of foods have reduced the concentration of acrylamide. The use of secondary metabolites such as polyphenols also reduces acrylamide concentration in fried food products. Other mitigation techniques such as asparaginase pre‐treatment and low‐temperature air frying with chitosan have been effective in mitigating the concentration of acrylamide. The combined pre‐treatment process along with the use of additives is the latest trend in acrylamide mitigation. © 2018 Society of Chemical Industry     

Synthesis of Phytonanocomposite of Zinc Oxide by <Emphasis Type="Italic">Ixora coccinea Linn</Emphasis> for Cancer Treatment

Bioactive peptides from Ixora coccinea Linn flowers have been reported to have anticancer activity against various cancer cells. Zinc oxide nanoparticle is the promising metal nanoparticle for anticancer applications. In the present work, ZnO was synthesized using I. coccinea Linn flower extract. The synthesized ZnO nanoparticle was found as phytonanocomposite of ZnO nanoparticle and bioactive components. The synthesized ZnO phytonanocomposite was confirmed using UV Spectroscopic analysis with maximum wavelength at 357.6 nm. The presence of bioactive peptides in the nanophytocomposite was confirmed using FT-IR analysis with strong peaks at 3402 and 1629 cm^?1. The particle size and surface characteristics of bioactive phytonanocomposite of ZnO was studied using Scanning Electron Microscope. The anticancer activity of zinc oxide nanocomposite of I. coccinea Linn flower extract was found to be efficient on MCF-7 cell line.     

Non-Targeted Metabolite Profiling Reveals Host Metabolomic Reprogramming during the Interaction of Black Pepper with Phytophthora capsici

Phytophthora capsici is one of the most destructive pathogens causing quick wilt (foot rot) disease in black pepper (Piper nigrum L.) to which no effective resistance has been defined. To better understand the P. nigrum–P. capsici pathosystem, we employed metabolomic approaches based on flow-infusion electrospray–high-resolution mass spectrometry. Changes in the leaf metabolome were assessed in infected and systemic tissues at 24 and 48 hpi. Principal Component Analysis of the derived data indicated that the infected leaves showed a rapid metabolic response by 24 hpi whereas the systemic leaves took 48 hpi to respond to the infection. The major sources of variations between infected leaf and systemic leaf were identified, and enrichment pathway analysis indicated, major shifts in amino acid, tricarboxylic acid cycle, nucleotide and vitamin B6 metabolism upon infection. Moreover, the individual metabolites involved in defensive phytohormone signalling were identified. RT-qPCR analysis of key salicylate and jasmonate biosynthetic genes indicated a transient reduction of expression at 24 hpi but this increased subsequently. Exogenous application of jasmonate and salicylate reduced P. capsici disease symptoms, but this effect was suppressed with the co-application of abscisic acid. The results are consistent with abscisic acid reprogramming, salicylate and jasmonate defences in infected leaves to facilitate the formation of disease. The augmentation of salicylate and jasmonate defences could represent an approach through which quick wilt disease could be controlled in black pepper.     

Enzymatic mitigation of acrylamide in fried potato chips using asparaginase from Aspergillus terreus

Acrylamide in foods is declared as carcinogen. In the present work, the effect of enzymatic pretreatment and other parameters like enzyme concentration, frying conditions with respect to temperature and time, size of potato chips, and effect of sodium chloride and citric acid on mitigation of acrylamide were studied. The concentration of acrylamide in fried potatoes after the pretreatment was found to be 815.63 μg kg^?1. The optimised asparaginase concentration for the mitigation of acrylamide was calibrated as 4 U mL^?1, and optimised frying time and temperature were 15 min and 170 °C, respectively. An in‐depth kinetic relationship for the effect of asparaginase on the mitigation of acrylamide was studied. The prime novelty of the project is focused on the immobilisation of asparaginase to nanomagnetic particles for redundant usage with stabilised enzyme activity. The work projected three stables cycles of asparaginase activity and on further usage of the immobilised enzyme resulted in decreased activity. The repeated use of immobilised asparaginase provides the advantage of decreasing cost in processing.     

Mosquito-larvicidal efficacy of gold nanoparticles synthesized from the seaweed,Turbinaria ornata (Turner) J.Agardh 1848

Malaria is considered a dreadful mosquito-borne infectious disease of human beings caused and spread by biting of the female mosquito Anopheles stephensi infected with a parasitic protozoan Plasmodium falciparum. Continuous application of chemicals/synthetic insecticides for vector control causes various problems such as resistant mechanism of mosquito, toxicity to nontarget aquatic organisms and disturbance to the microbial community of the soil. Currently, green synthesized nanoparticles are being employed in various biological processes including insect and pest control. The present investigation focused on the mosquito-larvicidal property of Turbinaria ornata-mediated gold nanoparticles (To-AuNPs) and its boiled aqueous extract (To-AE) against the malarial vector A. stephensi. The recorded lethal concentration (LC₅₀ and LC₉₀) values (µg/ml) of To-AE and To-AuNPs against fourth instar larvae of A. stephensi were 37.77 and 159.55 and 12.79 and 78.70, respectively. The To-AuNPs were characterized through UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive x-ray spectroscopy (EDX), zeta potential and dynamic light scattering (DLS) method. The presently synthesized gold nanoparticles through the single-step, eco-friendly method is a potentially effective mosquitocidal agent.     

Dual-cavity spectrometer for monitoring broadband light extinction by atmospheric aerosols

Abstract

Atmospheric Aerosols affect Earth’s climate directly by scattering and absorbing solar radiation. In order to study the optical properties of aerosols, we developed a broadband cavity-enhanced spectrometer that uses a supercontinuum laser source and a compact spectrometer, to measure simultaneously the extinction coefficient of aerosols over a broad wavelength region from 420 to 540?nm. The system employs a dual cavity approach with a reference and a sample cavity, accounting for changes in gases background and for laser spectral and intensity fluctuations. We tested the system with aerosolized salt particles and polystyrene latex spheres. We performed calculations using Mie theory and found good agreement with the measured extinction. We also found that the extinction coefficient of non-absorbing aerosol favorably compares with the scattering coefficient measured by a nephelometer. Finally, we generated soot particles and found an extinction Ångström exponent in good agreement with values reported in the literature. Wavelength dependent detection limits (1σ) for the instrument at 5?nm wavelength resolution and for an integration time of ～10?min were found to be in the range ～5?Mm^?1 to 13?Mm^?1. The broadband dual-cavity extinction spectrometer is simple and robust and might be particularly useful for laboratory measurements of the extinction coefficient of brown carbon aerosol. The laboratory tests suggest that the prototype is promising for future developments of a field-deployable instrument.

Copyright © 2020 American Association for Aerosol Research