Biosynthesised silver and copper nanoformulation as foliar spray to control bird's eye spot disease in tea plantations

Tea leaves have economic importance in preparation of the popular beverage of the world “tea”. Bird’s eye spot disease of tea leaves creates significant revenue loss in tea trade of many tea plant cultivating countries. Management of this disease by silver (AgNps) and copper (CuNps) nanoparticles that are biosynthesised by efficient antagonists was studied. The biocontrol agents like Pseudomonas fluorescens, Trichoderma atroviride and Streptomyces sannanensis were evaluated for nanoparticle synthesis against Cercospora theae isolates namely KC10, MC24 and VC38. Initially, the freshly prepared extracellular AgNps showed high disease control (59.42 – 79.76%), but the stability of antagonistic property in stored nanoparticles were significantly high in CuNps (58.71 – 73.81%). Greenhouse studies on various treatments imposed also showed reduced disease incidence percentage of 13.4, 7.57 and 10.11% when treated with CuNps synthesized by P. fluorescens, T. atroviride and S. sannanensis respectively. Various treatment schedule in fields suggested the use of Bionanocopper@1.5 ppm for highest yield (3743 kg/ha) with 66.1% disease prevention. The results suggest the use of biosynthesised CuNps using Streptomyces sannanensis for controlling the tea plant pathogens causing foliar disease with higher stability in releasing the antagonistic activity during sporadic disease incidence of bird’s eye spot disease in tea plants.Inspec keywords: silver, copper, crops, plant diseases, nanoparticles, air pollution, agrochemicals, nanobiotechnologyOther keywords: biosynthesised silver, biosynthesised copper, nanoformulation, foliar spray, bird eye spot disease control, tea plantations, tea leaves, economic importance, revenue loss, tea trade, tea plant cultivating countries, silver nanoparticles, AgNps, copper nanoparticles, CuNps, biocontrol agents, nanoparticle synthesis, Cercospora theae isolates, KC10, MC24, VC38, greenhouse studies, antagonistic property, P. fluorescens, T. atroviride, S. sannanensis, fungicides, synthetic nanomaterials, bionanomaterials, disease prevention, green leaf yield, BionanoCu, tea plant pathogens, foliar disease     

Temperature rise in microwave p-i-n diodes: A computer aided analysis

Results of a computer aided thermal analysis of microwave p-i-n diodes are presented in this paper. The nonlinear heat flow equations in one dimension are solved using the central finite difference method of Leibman's formulation taking into account the temperature dependence of thermal conductivity and specific heat. Results are presented showing the temperature profile inside the device as a function of microwave pulsewidth and power dissipation. The effect of a heat sink on the temperature rise is also shown. The main conclusion arrived at is that the nonlinear thermal properties lead to higher temperature rise in the device and larger thermal time constants than could be expected otherwise. The method used for calculation is applicable for other solid state devices like the TRAPATT, the fast recovery thyristor, and power transistors where similar orders of power levels are involved.     

Synthesis of titanium oxide and titanium nitride nano-particles with narrow size distribution by supersonic thermal plasma expansion

The paper reports the synthesis of nano-crystalline ceramics like titanium dioxide and titanium nitride using a plasma chemical experimental reactor powered by a multi-segment (cascaded) arc plasma torch. The precursor-laden plasma beam emerging from the torch anode section expands supersonically through a converging nozzle to a low-pressure collection chamber. This results in a uniform and controlled gas dynamic quenching ensuring rapid synthesis of pure, un-coagulated free-flowing particles with a narrow size distribution. Simple Langmuir probes and calorimetric energy balance methods are used for plasma and reactor characterization, while X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS), Raman and X-ray photoelectron spectroscopy (XPS) techniques have been used for product analysis. It is shown that size distribution of both the product particles is comparatively narrower than that found in most thermal plasma assisted laboratory synthesis studies. The expansion process was observed to produce a non-equilibrium electron population, which could charge up the particles after nucleation and hence could curb unwanted coagulation.     

Numerical investigation of nanoparticle synthesis in supersonic thermal plasma expansion

In this communication, we are numerically investigating the nucleation and growth of nanoparticles in the context of a supersonically expanded thermal plasma assisted process, using the Nodal General Dynamic Equations (NGDE) model. The dependence of particle size distribution on reactant injection rate and sample collection chamber pressure is investigated. The possible effect of particle charging in the plasma environment on nucleation and growth of particle sizes is also studied. Results are compared with findings from an actual experimental reactor system in the laboratory of the authors.     

Hydrothermal synthesis of PtRu nanoparticles supported on graphene sheets for methanol oxidation in direct methanol fuel cell

Platinum–ruthenium (PtRu) nanoparticles are dispersed on graphene nanosheets and multi-walled carbon nanotubes (MWCNTs) via a hydrothermal method. Transmission electron microsocopy (TEM) observation shows the uniformly dispersed nanoparticles and the average nanoparticle size has been calculated. The electrochemical measurements demonstrate that the Pt–Ru/graphene catalyst exhibits about two times higher mass activity and better tolerance to poisoning species in methanol electro-oxidation than the Pt–Ru/MWCNTs catalyst. This study indicates that the PtRu anodic catalyst synthesized by hydrothermal method can be applied for direct methanol fuel cells (DMFC).     

Efficient composite bipolar plate reinforced with carbon fiber and graphene for proton exchange membrane fuel cell

The composite bipolar plates are developed using natural graphite, carbon black, and carbon fiber, along with 1% graphene with phenol formaldehyde (resole) resin. The graphene is developed by thermo-chemical exfoliation of natural graphite and characterized by XRD, Raman, FESEM, and AFM analyses. The synthesized graphene is monolayer graphene with a minimum thickness of 1 Å. The bipolar plates are developed using compression molding technique and thoroughly characterized considering stringent benchmarks (US-DOE and Plug Power Inc.) for PEMFC viz., electrical conductivity, flexural strength, deflection at mid-point, and corrosion current density. The composite bipolar plate showed excellent corrosion resistance to the rigorous fuel cell environment. All the required properties are achieved by the developed composite bipolar plate for PEMFC application. The fuel cell is fabricated with the developed bipolar plate and the performance of the fuel cell is studied. The incorporation of graphene has improved the fuel cell performance significantly.     

A 640-Gbps, 15.2344-b/s/Hz full-duplex optical fiber/wireless single-channel coherent communication system using IQM-based DP-256-QAM and DSP techniques

Photonic Network Communications - A full-duplex optical fiber/wireless single-channel coherent communication system is presented for high-speed data center interconnections. In-phase and quadrature...     

Experimental and Numerical Investigation of Hybrid River Training Works using OpenFOAM

Water Resources Management - Riverbank erosion is widespread in alluvial rivers in India and elsewhere. River training works are frequently used to aid in the prevention of these losses by...     

Effect of the reaction conditions on the photopolymerization of methyl methacrylate by diethyl dithiocarbamato‐(1,2)‐propane diol

The photopolymerization of methyl methacrylate (MMA) through the use of diethyl dithiocarbamato‐(1,2)‐propane diol (DCPD) was studied. The photoinitiator was synthesized from 3‐chloro‐1,2‐propane diol and sodium diethyl dithiocarbamate in a solvent mixture of acetone and anhydrous ethanol. The photopolymerization was carried out in a Heber multilamp photochemical reactor (COMPACT‐LP‐MP88) (Heber Scientific, Chennai, India) at 254 nm. The effects of the reaction conditions on the polymerization of MMA were studied. The conversion and molecular weight increased with an increase in the monomer concentration and reaction time. However, for the DCPD‐to‐MMA molar ratio, a critical value was found for maximum conversion. The results suggested the living radical nature of the photoinitiator, which was further investigated by the preparation of a block copolymer with styrene. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2320–2328, 2005