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Rare earth metal oxide (RE2O3; RE = Nd, Gd, and Yb) incorporated polyindole composites: gravimetric and volumetric capacitive performance for supercapacitor applications
No full textIncorporation of rare earth metal oxides in the polyindole (PIn) matrix seems to be an effective way for improving the electrochemical and stability features of PIn. PIn being a member of the fused aromatic molecular structural family draws attention as a potential electrode material for supercapacitors. Incorporation of rare earth metal oxides improves the gravimetric performance of PIn by introducing additional pseudocapacitance and also exhibits fair volumetric capacitance owing to its high packing density. PIn composites with RE2O3 (RE = Nd, Gd, and Yb) show augmented gravimetric and volumetric capacitance. An Nd2O3 incorporated PIn composite with a ratio of 1 : 1 exhibits an enhanced gravimetric capacitance of 401 F g(-1) and a volumetric capacitance of 516 F cm(-3). This composite also exhibits markedly enhanced values of cyclic stability, coulombic efficiency, power density, and energy density. The established synergy between RE2O3 and PIn together with structural modifications results in much improved electrochemical properties of the developed composites
Carbonaceous Species of PM2.5 in Megacity Delhi, India During 2012-2016
No full textOrganic carbon (OC) and elemental carbon (EC) in PM2.5 were estimated to study the seasonal and inter-annual variability of atmospheric total carbonaceous aerosols (TCA) at an urban site of megacity Delhi, India for 5 years from January, 2012 to December, 2016. The annual average (+/- standard deviation) concentrations of PM2.5, OC, EC and TCA were 128 +/- 81, 16.6 +/- 12.2, 8.4 +/- 5.8 and 34.5 +/- 25.2 A mu g m(-3), respectively. During the study, significant seasonal variations in mass concentrations of PM2.5, OC, EC and TCA were observed with maxima in winter and minima in monsoon seasons. Significant correlations between OC and EC, and OC/EC ratio suggested that vehicular emissions, fossil fuel combustion and biomass burning could be major sources of carbonaceous aerosols of PM2.5 at the sampling site of Delhi, India
Characterization of Capacitance Standards at High Frequency at National Physical Laboratory, India
No full textFour-terminal-pair air dielectric capacitance standards with nominal values of 1000 and 100 pF have been characterized up-to 10 MHz at NPLI. The procedure employed involves the determination of all capacitive and inductive parameters of the simple electrical-equivalent-circuit-model of these capacitance standards. The effective capacitance of each standard has also been computed as a function of frequency from 1 kHz to 10 MHz. The capacitive parameters have been measured at 1 kHz while inductive parameters have been estimated up to 10 MHz using linear regression analysis by employing least-squares-approximation method. The paper highlights the computation procedure of impedance terms which further requires the determination of various capacitive and inductive terms involved in the calculation of effective capacitance. The method employed for the estimation of inductive parameters as a function of frequency is also discussed in detail. The present work will help in the establishment of metrological traceability of capacitance standards at high-frequency at NPLI which will be further used to establish calibration facility for LCR meters and RF impedance analyzers for capacitance parameter up-to 10 MHz
Consequences of phase separation on magnetotransport in dc magnetron sputtered Sm0.50Sr0.50MnO3 thin films on LSAT substrate
No full textSingle crystalline thin films of Sm0.50Sr0.50MnO3 (SSMO) (thickness similar to 200 nm) were prepared on LSAT (100) single crystal substrates by dc magnetron sputtering. The X-ray diffraction theta-2 theta and omega-2 theta scan reveals that these films (i) have very good crystallinity, (ii) are oriented along out-of-plane c-direction, and (iii) are under small tensile strain. Temperature and magnetic field dependent electrical transport of these films shows (i) sharp paramagnetic insulator (PMI) to ferromagnetic metal (FMM) transition, (ii) large enhancement in TIM when subjected to magnetic field, (iii) hysteretic variation in resistivity with magnetic field, and (iv) huge occurrence of magnetoresistance near PMI-FMM transition. The magnetic state in the FMM (T < T-C) regime resembles cluster glass, which is formed by the presence of charge ordered-antiferromagnetic clusters in the ferromagnetic matrix. The results shown in the present study could be regarded as the consequence of strong nature of phase separation in these films due to competing FMM and AFM-COI phases in these films which is known to be the generic feature of low bandwidth manganites
Thermoelectric properties of p-type sb-doped Cu2SnSe3 near room and mid temperature applications
No full textIn this study, we report low and mid temperature range thermoelectric properties of Sb-substituted Cu2SnSe3 compounds. The Cu2Sn1-xSbxSe3 (0 <= x <= 0.04) alloys were prepared using conventional solid-state reaction followed by spark plasma sintering. The crystal structure was characterized using XRD and it reveals that all the samples exhibit cubic structure with space group 4 3m. The electrical transport characteristics indicate degenerate semiconducting behavior. Electrical resistivity was found to follow small polaron hopping (SPH) model in the entire temperature range of investigation. The Seebeck coefficient data reveals that the majority of charge carriers are holes and the analysis of Seebeck coefficient data gives negative values of Fermi energy indicating that the Fermi energy is below the edge of valence band. The electronic contribution (kappa(e)) for total thermal conductivity is found to be less than 1%. The maximum ZT value of 0.64 is observed for the sample with x = 0.03 (at 700 K) which is approximately 2.3 times that of the pristine sample
Biospectroscopic analysis of human breast cancer tissue: probing infrared signatures to comprehend biochemical alterations
No full textBreast cancer (BC) is one of the most studied and lead-
ing form of malignancy in human females. Currently,
studies conducted in the field of breast cancer focuses on
its early detection using noninvasive or minimally inva-
sive techniques in lieu of traditional excisional biopsy, as
cancer treatment is often simpler and effective, when
diagnosed at an early stage. Mammography is the first
step, usually performed in diagnosing breast cancer, but
at times mammogram may not be able to provide a clear
picture. In addition, biopsy is performed to confirm the presence or absence of tumor, which is associated with false-positive results. Consequently, the limitations of current screening methods have shifted the focal area of
on cological research in applying biospectroscopy tech-
niques for diagnostics (Gajjar et al.,2014
Spatial variations of intra-city urban heat island in megacity Delhi.
No full textThis study examines the variation of intra-city Urban Heat Island (UHI) in megacity Delhi by the mobile transverse measurement technique and spatial maps of UHI along the mobile routes have been generated for the city by using the ordinary kriging interpolation tool of ArcGIS. Meteorological data was collected by mobile surveys under clear sky weather days in monsoon and winter months of 2014 using two HOBO data loggers installed on a vehicle along the routes which covered many parts of Delhi intersecting vertical and horizontal transects capturing different land use patterns of the city. UHI values obtained through interpolation were validated with UHI obtained from temperature measurements at five fixed sites spread over the Delhi region, which were found in good agreement (R-2 = 0.91). The variability existing in the two seasons studied has been shown by low UHI values obtained in the monsoon season and high UHI values in winter season. The diurnal pattern of UHI showed higher UHI during the nighttime period, compared to morning and noon periods. The results show variable UHI in different regions of Delhi covered by mobile routes with high UHI values of >6 degrees C observed during the winter period
Fabrication of a p-n Heterojunction Using Topological Insulator Bi2Te3-Si and Its Annealing Response
No full textA junction device has been fabricated by growing p-type Bi2Te3 topological insulator (TI) film on an n-type silicon (Si) substrate using a thermal evaporation technique. Annealing using different temperatures and durations was employed to improve the quality of the film, as confirmed by microstructural study using x-ray diffraction (XRD) analysis and atomic force microscopy (AFM). The p-n diode characteristics of the junction devices were studied, and the effect of annealing investigated. An improved diode characteristic with good rectification ratio (RR) was observed for devices annealed for longer duration. Reduction in the leakage or reverse saturation current (I-R) was observed with increase in the annealing temperature. The forward-bias current (I-F) dropped in devices annealed above 400 degrees C. The best results were observed for the sample device annealed at 450 degrees C for 3h, showing figure of merit (FOM) of 0.621 with RR approximate to 504 and = 0.25 mu A. In terms of ideality factor, the sample device annealed at 550 degrees C for 2h was found to be the best with n = 6.5, RR approximate to 52.4, I-R = 0.61 mu A and FOM = 0.358. The majority-carrier density (N-A) in the p-Bi2Te3 film of the heterojunction was found to be on the order of 10(9)/cm(3) to 10(11)/cm(3), quite close to its intrinsic carrier concentration. These results are significant for fundamental understanding of device applications of TI materials as well as future applications in solar cells
Non lithographic block copolymer directed self-assembled and plasma treated self-cleaning transparent coating for photovoltaic modules and other solar energy devices
No full textThrough a combination of sol-gel based self-assembly and plasma based approach we have developed highly transparent, self-ordered, superhydrophilic and photoactive TiO2 thin film coatings. TiO2 sol used for such coatings comprises a block copolymer which functions as a structure directing agent. This structure directing agent aid to formation of regular pores in the TiO2 thin film, thereby, remarkably reducing the refractive index values (similar to 1.31) and enhancing the transparency (4% antireflection gain) of the coatings. Further, such porous TiO2 coatings show an excellent ability to photo-decompose organic pollutants, due to the photocatalytic ability of such metal oxide semiconductor. Enhancement in the photocatalytic activity has been obtained by porous surface created using a block copolymer and shifting the band gap energy by incorporating nitrogen so as to utilize part of the visible region of the solar spectrum for photocatalysis. An optimum condition is achieved by varying the RF self-bias potential and time of plasma treatment. Nitrogen plasma treatment, in addition to enhancing the photocatalytic activity of TiO2 is also found to enhance the mechanical stability and hydrophilicity, without hampering the optical transmission of coatings. Such coatings are also found to exhibit superhydrophilicity with water contact angle (WCA) < degrees 5 under optimized condition. Thus, the coatings developed, qualify as a suitable candidate to be applied on solar PV panel and other energy devices. Treatment with nitrogen plasma extends the photocatalytic activity towards visible region of the spectrum and also ensures the mechanical stability of the otherwise porous network
Tailoring of the chlorine sensing properties of substituted metal phthalocyanines non-covalently anchored on single-walled carbon nanotubes
No full textTo investigate how central metal tunes the synergetic interactions between substituted metallo-phthalocyanine and single-walled carbon nanotubes in enhancing the gas sensing properties, a comparative study has been performed by varying the central metal ion in fluorinated metal phthalocyanines and single-walled carbon nanotube hybrid. Hybrids of metal(ii)-1,2,3,4,8,9,10,11,15,16,17,18-24,25-hexa-decafluoro-29H,31H-phthalocyanine/single-walled carbon nanotube (F16MPc/SWCNTs-COOH, where M = Co, Zn) have been synthesized through - stacking interactions using the solution route. Spectroscopic (FT-IR, UV-vis, XPS and Raman), electron microscopic (TEM and FE-SEM) and TGA investigations have confirmed the successful functionalization and interaction of SWCNTs-COOH with F16MPc. Parts per billion (ppb) level Cl-2-selective chemiresistive gas sensors have been fabricated on glass substrates with precoated gold electrodes by using these hybrids. The responses of various F16MPc/SWCNTs-COOH sensors have demonstrated the central metal ion-dependence in the sensitivity of Cl-2