654 research outputs found
Sort by
Synthesis and investigation of photonic properties of surface modified ZnO nanoparticles with imine linked receptor as coupling agent- for application in LEDs
No full textWet chemical precipitation route is developed for the synthesis of ZnO nanoparticles using a dipodal receptor as capping agent to control the size and shape of ZnO nanoparticles and also to passivate the surface defects. The capping of ZnO nanoparticles with dipodal receptor is characterized with NMR and IR spectroscopy. EDX analyses also confirmed the presence of organic receptors together with ZnO nanoparticles. The morphology and size of surface modified ZnO nanoparticles is checked by SEM, TEM and DLS spectroscopic techniques. The surface decorated ZnO nanoparticles demonstrate emission peak at 333 nm. The emission peak at 333 nm in case of surface capped ZnO demonstrate fewer surface defects present in comparison to their bulk counterpart, where blue, red, green, yellowish green emission peaks are present. The photophysical studies of ZnO nanoparticles are further carried in presence of metal ions where it is observed that the binding with Mn(II) result in increase in fluorescence intensity. The three fold increase in fluorescence intensity of ZnO nanoparticles in presence of Mn(II) can be utilized in case of lighting devices, where high quantum yield is desirable. To the best of our knowledge, this manuscript represents the first surface decorated ZnO nanoparticles for their application in lighting devices
Split-nanotube-based negative index metamaterial for midinfrared wavelengths
No full textA design of split-nanotube-based negative index metamaterial for the infrared spectrum has been proposed. The proposed design and its operation are similar to that of a split-ring resonator (SRR) without inheriting the fabrication difficulties associated with conventional SRR. A negative refractive index has been achieved using a split-nanotube in combination with a periodic array of metallic wires between 1.5 and 3.3 μ m .
© 2017 Society of Photo-Optical Instrumentation Engineers (SPIE
Classification of heavy metal ions present in multi-frequency multi-electrode potable water data using evolutionary algorithm
No full textAccess to potable water for the common people is one of the most challenging tasks in the present era. Contamination of drinking water has become a serious problem due to various anthropogenic and geogenic events. The paper demonstrates the application of evolutionary algorithms, viz., particle swan optimization and genetic algorithm to 24 water samples containing eight different heavy metal ions (Cd, Cu, Co, Pb, Zn, Ar, Cr and Ni) for the optimal estimation of electrode and frequency to classify the heavy metal ions. The work has been carried out on multi-variate data, viz., single electrode multi-frequency, single frequency multi-electrode and multi-frequency multi-electrode water samples. The electrodes used are platinum, gold, silver nanoparticles and glassy carbon electrodes. Various hazardous metal ions present in the water samples have been optimally classified and validated by the application of Davis Bouldin index. Such studies are useful in the segregation of hazardous heavy metal ions found in water resources, thereby quantifying the degree of water quality
Electrochemical sensing of nitro-aromatic explosive compounds using silver nanoparticles modified electrochips
No full textIn the present study an electrochemical deposition method for glycine-stabilized silver nanoparticles (Glyc-AgNPs) at screen printed electrodes is shown in a single step with minimal sample preparation. The advantage of this method is the direct assembly of Glyc-AgNPs at the electrode surface without external modification. The Glyc-AgNPs were characterized for their size, crystallinity and redox activity. The nanoparticles were further used for electrochemical sensing of 2,4,6-tri-nitro toluene (TNT) and di-nitro benzene (DNB), i.e. nitro-aromatic explosive compounds using differential pulse voltammetry (DPV). The Glyc-AgNP modified electrochip revealed significantly more sensitivity towards TNT as compared to DNB, as evident from the current intensity obtained due to the electrochemical reduction process. Earlier studies have suggested that tri-nitro compounds are more easily reduced as compared to mono- and di-nitro compounds, which is hypothesized as the main reason for the observed sensitivity for TNT. A linear response was observed in the range from 1 × 10−10 to 0.1 M for TNT, and 1 × 10−7 to 0.1 M for DNB. The results obtained with spiked samples provided solid grounds for future field trials with the developed sensing device
Long period fiber grating based sensor for the detection of triacylglycerides
No full textIn this paper, stable, label free enzyme based sensor using long period fiber grating (LPG) is described for the detection of triacylglycerides. A stable covalent binding technique for lipase enzyme immobilization on an optical fiber is reported. An active and stable attachment of the functional group of the enzyme on the fiber surface is achieved using this method. Enzyme immobilization is confirmed by Scanning Electron Microscopy (SEM) and Raman Spectroscopy. The stability is confirmed by lipase p-nitrophenyl palmitate (PNP) assay. In contrast to widely used amperometric based biosensor, where a number of enzymes are required, only one enzyme, namely, lipase is required in our sensor. The sensor shows optimum response within one minute at a temperature of 37 °C and pH of 7.4. The sensor is based on the shift in resonance wavelength of the LPG transmission spectrum due to the interaction of triacylglycerides with the enzyme. The biosensor is highly specific towards triacylglycerides and is unaffected by the presence of many other interfering substances in serum. Interaction between the bio-molecules and the long period grating surface is also modeled theoretically using a four layer model for the LPG fiber with the bio-recognition layer and the results obtained are consistent with experimentally obtained results. The sensor shows a high sensitivity of 0.5 nm/mM and a low detection limit of 17.71 mg/dl for the physiological range of triacylglycerides in human blood
Low temperature processed graphene thin film transparent electrodes for supercapacitor applications
No full textThe highest conductivity in graphene oxide based thin film electrodes has been achieved using high temperature annealing at 1100 °C. This is unfavorable for low cost production and application over plastic substrates. Here we report highly conducting graphene thin films using spin coating of a functionalized graphene solution over various substrates. The bridged graphene nanoflakes provide higher conducting pathways in the thin film, enabling electrodes to be fabricated at low temperatures of the order 150 °C. These thin film electrodes show remarkable sheet resistance of the order 0.4 kΩ sq.−1 and transmittance up to 94%. This work demonstrates that graphene based transparent electrodes have the potential to replace existing doped metal oxide based electrodes. The electrochemical performance of graphene thin films as active supercapacitor electrodes was evaluated using cyclic voltammetry. The calculated specific capacitance was found to be ≈49, 48, 48 and 68 F g−1 for the graphene thin film electrodes fabricated at spin speeds of 1000, 1200, 1400 and 1600 rpm, respectively. The above electrochemical performance indicates that the graphene electrodes show large specific capacitance and could be very attractive for several applications including wearable electronics, smart windows and advanced display panels
A Web Server and Mobile App for Computing Hemolytic Potency of Peptides
No full textNumerous therapeutic peptides do not enter the clinical trials just because of their high hemolytic activity. Recently, we developed a database, Hemolytik, for maintaining experimentally validated hemolytic and non-hemolytic peptides. The present study describes a web server and mobile app developed for predicting, and screening of peptides having hemolytic potency. Firstly, we generated a dataset HemoPI-1 that contains 552 hemolytic peptides extracted from Hemolytik database and 552 random non-hemolytic peptides (from Swiss-Prot). The sequence analysis of these peptides revealed that certain residues (e.g., L, K, F, W) and motifs (e.g., “FKK”, “LKL”, “KKLL”, “KWK”, “VLK”, “CYCR”, “CRR”, “RFC”, “RRR”, “LKKL”) are more abundant in hemolytic peptides. Therefore, we developed models for discriminating hemolytic and non-hemolytic peptides using various machine learning techniques and achieved more than 95% accuracy. We also developed models for discriminating peptides having high and low hemolytic potential on different datasets called HemoPI-2 and HemoPI-3. In order to serve the scientific community, we developed a web server, mobile app and JAVA-based standalone softwar
Design and analysis of a highly nonlinear composite photonic crystal fiber for supercontinuum generation: visible to mid-infrared
No full textA composite photonic crystal fiber structure has been designed with tellurite as the cladding and chalcogenide as a core material. To increase nonlinearity, rods of the chalcogenide glass material have been inserted around the core region. The reported structure offers very high nonlinearity of 1042 W−1 Km−11042 W−1 Km−1 at 2800 nm pump wavelength with low and flattened dispersion of approximately −11 ps·nm−1 Km−1−11 ps·nm−1 Km−1. An effective mode area of 6.46 μm26.46 μm2 of the propagating mode has been achieved as at pump wavelength. Such a highly nonlinear composite photonic crystal fiber structure is a potential candidate for nonlinear applications, such as slow-light and supercontinuum generation. Pumping at 2800 nm results in a supercontinuum spectrum spanning 0.5–4.7 μm using 8 mm long photonic crystal fiber pumped with femtosecond laser pulses with peak power of 3 kW
Characterization of Quality Assurance Properties of Biogenic Volatile Organic Compounds with an Emphasis on the Breakthrough Behavior, Recovery, and Temporal Stability
No full textIn this research, we investigated the breakthrough volume (BTV) and temporal performance of two types of sorbent tube (ST) sorbent beds toward 10 (target) biogenic volatile organic compounds (BVOCs) ((1) isoprene, (2) (+)-α-pinene, (3) camphene, (4) (+)-β-pinene, (5) (+)-3-carene, (6) α-phellandrene, (7) α-terpinene, (8) (R)-(+)-limonene, (9) γ-terpinene, and (10) p-cymene) and two (reference) anthropogenic volatile organic compounds (AVOCs) ((11) benzene and (12) toluene). The analysis of their vaporized liquid-phase working standards was carried out using thermal desorption–gas chromatography–mass spectrometry (TD-GC/MS). To this end, the performance of two ST types (CC (Carbopack C) and CBX (Carbopack C, Carbopack B, and Carbopack X)) was tested as a function of a few key variables, e.g., sorbent type, N2 gas purge volume, and sampling temperature. The CBX ST gave recoveries of 100 ± 10% at 60 °C for two BVOCs (camphene and α-terpinene). However, three compounds (isoprene, (+)-α-pinene, and (+)-β-pinene) showed poor recoveries (0.7, 59.3, and 11.3%, respectively), whilst p-cymene recorded an excess recovery (~ 190%). In contrast, for the CC ST, BT for (+)-α-pinene and camphene increased with purge volume, while isoprene was not detected. Accordingly, the range of BTV5% and BTV50% values (L/g) for each compound with CC ST were 1.7 (toluene)–17 (camphene) and 15 (toluene)–570 ((+)-α-pinene), respectively. In summary, a three-bed CBX with the higher BTV is the preferred choice for environmental sampling for a wide range of BVOCs compared to a one-bed CC ST. The recovery of CBX ST for 10 out of 12 analytes (after > 150 reconditioning/loading/TD cycles) remained constant in terms of response factor, while the response factors of isoprene and β-pinene were highly variable. Both the present work and the reported literature recoveries showed similar and divergent results which are discussed in terms of high temperature on-sorbent reaction
Improved performance of carbon nanotubes—manganese doped cadmium sulfide quantum dot nanocomposite based solar cell
No full textThe nanocomposites of carbon nanotubes with quantum dots (MWCNT-QDS) display the capability of light induced charge dissociation and transport, which make them suitable for photovoltaic applications. The present work reports the coupling of multiwalled CNT (MWCNT) with L-cysteine (2-amino 3-mercaptopropionic acid) capped manganese doped cadmium sulfide QDs (CdS:Mn). The confirmation of the MWCNT-CdS:Mn nanocomposite formation is done with various instrumental techniques. Current–voltage studies of the MWCNT-CdS:Mn thin film indicate their semiconducting behavior. Further, cyclic voltammetry and frequency response analyses of the above MWCNT-CdS:Mn thin film have highlighted their potential application as a photoanode material in dye sanitized solar cells. It has been demonstrated that the use of MWCNT-CdS:Mn nanocomposite as a photoanode material offer better photocurrent characteristics as compared to QDS alone