A QUAD-BAND MONOPOLE ANTENNA WITH DEFECTED GROUND PLANE FOR L-BAND/WIMAX/WLAN APPLICATIONS

In this paper, a planar quad band monopole antenna excited by the microstrip line feed is proposed for L-band, WiMAX and WLAN applications. The proposed antenna is composed of radiating element in the form of L, U and inverted L-shaped strips on the top surface of substrate and defected ground plane on the bottom surface. By adjusting the length of the strips, the resonant frequencies can be reformed individually. The overall dimension of the prototype of the proposed quad band antenna is 50x35x1.6mm³. From the measured results it is found that the proposed antenna has exhibited four distinct operating bands (return loss less than -10dB) of 170MHz (from 1.16 to 1.33GHz), 550MHz (from 1.53 to 2.08GHz), 470MHz (from 2.43 to 2.90GHz) and 3930MHz (from 3.77 to 7.70GHz). First two bands operated in L-band, third band can be used for WiMAX lower band (2.5GHz) and bandwidth of fourth band may be used for WLAN (5.2/5.8 GHz) and WiMAX (5.5GHz) applications. It is also observed that the proposed antenna has good radiation patterns and acceptable gains over the whole operating bands. The design process and parametric analyses are explained with the help of simulation software HFSS v.11

Soil conservation issues in India

Despite years of study and substantial investment in remediation and prevention, soil erosion continues to be a major environmental problem with regard to land use in India and elsewhere around the world. Furthermore, changing climate and/or weather patterns are exacerbating the problem. Our objective was to review past and current soil conservation programmes in India to better understand how production-, environmental-, social-, economic- and policy-related issues have affected soil and water conservation and the incentives needed to address the most critical problems. We found that to achieve success in soil and water conservation policies, institutions and operations must be co-ordinated using a holistic approach. Watershed programmes have been shown to be one of the most effective strategies for bringing socio-economic change to different parts of India. Within both dryland and rainfed areas, watershed management has quietly revolutionized agriculture by aligning various sectors through technological soil and water conservation interventions and land-use diversification. Significant results associated with various watershed-scale soil and water conservation programmes and interventions that were effective for reducing land degradation and improving productivity in different parts of the country are discussed

A simple electrochemical approach to fabricate functionalized MWCNT-nanogold decorated PEDOT nanohybrid for simultaneous quantification of uric acid, xanthine and hypoxanthine

Medical diagnostics and detection of food spoilage require estimation of hypoxanthine (HX), xanthine (XN), and uric acid (UA). A selective sensing platform has been proposed for simultaneous detection of all these species. Functionalized multi-walled carbon nanotube (fMWCNT) stabilized nanogold decorated PEDOT:TOS polymeric nanocomposite (Au-PEDOT-fMWCNT) was synthesized through rapid one-step electropolymerization to enhance conductivity and active surface area by several folds. Electrochemical activities of the proposed sensing platform were analyzed by cyclic voltammetry (CV) and differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS). Analyses through SEM, FESEM and TEM were performed to explore the surface morphology and elemental analysis of the polymeric nanohybrid was investigated by XPS, Raman, FTIR, XRD spectroscopy. Electro-catalysis of UA, XN and HX occurred at low oxidation potentials i.e. 0.082, 0.463 and 0.808 V, respectively in the optimized conditions. The uniquely designed simple, interference free Au-PEDOT-fMWCNT/GCE sensor exhibited high selectivity, good reproducibility, reusability (similar to 180 times) and stability (similar to 3 month) with excellent sensitivity of 1.73, 14.31 and 3.82 mu A mu M-1 cm(-2) for UA, XN and HX, respectively. The sensor exhibited linear ranges of detection as 0.1-800, 0.05-175 and 0.1-150 mu M with detection limits of 199.3, 24.1 and 90.5 nM for quantification of UA, XN and HX respectively. The performance of the proposed sensor was validated by addition of UA, XN and HX in human serum, urine and fish samples by comparing to those using HPLC. The results indicated good applicability of the proposed sensor for simultaneous detection of UA, XN, HX in real biological fluids. (C) 2020 Elsevier B.V. All rights reserved

A new diagnostic tool for measuring total antioxidants in tea

The purpose of this research was to develop a sensory system to measure antioxidant level in tea with a view to assessing the quality of different grades of tea available in the market. We proposed an easy, reliable sensory system to quantify the total antioxidant capacity (TAC) of tea infusion. A preformed ABTS [2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate)] radical cation (ABTS(+)) was used in the bulk electrolyte in presence of glassy carbon (GC) or platinum (Pt) working electrode. Total antioxidant present in sample was determined by amperometric response at optimum redox potential of 0.552 V dictated by cyclic voltammogram. Linear calibrations for standard antioxidants such as gallic acid, caffeic acid, ascorbic acid, catechin hydrate and chlorogenic acid were obtained in the range of 1-250 mu g/mL. Quantitative estimation of antioxidants in tea samples were expressed as gallic acid equivalent (GAE) with a detection limit of 2.34 mu g/mL. The amperometric sensor showed optimum response at pH 5.8 at around 25 degrees C. Excellent correlations were obtained with standard spectrophotometric assays. The system might be useful for quality control of various grades of tea due to its specificity, simplicity and quick response of measurement procedures. The present research gave excellent opportunity to grade tea on the basis of antioxidant levels. Similarly the system might have useful applications in determining antioxidants in other common food items such as fruit juices and other beverages

Dynamic simulation of propylene polymerization in continuous flow stirred tank reactors

The dynamic operation of an ideal continuous-flow stirred tank slurry reactor for propylene polymerization has been studied. A simple model is developed, which could be used for optimal computer control using advanced strategies. Step increases in input feed rates of propylene, solvent, and catalyst are used as the stimuli or forcing functions. It is assumed that the volume of the slurry in the reactor is maintained constant during the period. Responses of three output variables are studied, namely, monomer concentration in the liquid, volume-fraction of solids in the exiting slurry, and average mass fraction of catalyst in the exiting macroparticles. It is found that the transients last for about five times the mean residence time of the reactor. Competing effects of changes in the diffusional resistance, number density of catalyst particles, and washout and dilution effects lead to interesting dynamic results

Simulation of propylene polymerization: an efficient algorithm

Multigrain type models for propylene polymerization suffer from the drawback that they take excessive computer time to predict the degree of polymerization (DP) and the polydispersity index (Q) of the polymer produced. An efficient algorithm using adaptive grid-point spacing in a finite-difference technique has been developed to overcome this defect. Using this algorithm, we have studied the effects of catalyst deactivation as well as multiplicity of catalyst sites, on the rate of polymerization, and on the values of DP and Q. The improved algorithm can easily be used to model industrial reactors where additional physicochemical effects are present

Steady state simulation of continuous-flow stirred-tank slurry propylene polymerization reactors

Methodologies are developed for studying the steady-state operation of propylene polymerization in continuous-flow stirred tank reactors (CFSTRs). The effect of several reactor operating variables and reaction variables (e.g., mean residence time, catalyst deactivation rate, multisite catalyst activity, etc.) on polymer properties is obtained. It is found that a compromise has to be made between the yield of the polymer and its polydispersity index, since they usually show opposing trends with the mean residence time

Interference-Free Electrochemical Detection of Nanomolar Dopamine Using Doped Polypyrrole and Silver Nanoparticles

This paper presents a new approach to detect dopamine in nanomolar range using an electrochemical sensor utilizing a composite made of chitosan-stabilized silver nanoparticles and p-toluene sulfonic acid-doped ultrathin polypyrrole film. Studies included cyclic voltammogram, amperometry, differential pulse voltammetry and also investigation by electrochemical impedance spectroscopy. A detection limit of 0.58 nM was achieved in the linear range 1 x 10(-9) M to 1.2 x 10(-7) M. High sensitivity towards DA, good reproducibility and long-term stability have been demonstrated without interference from ascorbic acid, uric acid, epinephrine, l-dopa, glucose. The sensing system was successfully applied for quantitative determination of dopamine in commercially available human blood serum.Funding Agencies|DST (INSPIRE), New Delhi</p