IR@NPL
Not a member yet
3815 research outputs found
Sort by
An accurate inner diameter measurement
No full textThe inaccurate deflection behavior of the probing system degrades the performance of the diameter-measuring machines. In this experiment, the probing is improved, applying an autocollimator and an angular positioning datum. We have devised this datum using a liquid wedge. A ring gauge is chosen as a workpiece to evaluate the deflection behavior of the probing system. The improved uncertainty of the probing is found as low as 40 nm. Subsequently, the inner diameter of the ring gauge is measured on this experimental setup. By employing a simulation, we aligned the workpiece. The deflections of the stylus are optimized to achieve zero deflection error at the zenith points. Consequently, the swing of the probe at the zenith points is combined with the rectilinear displacement of the workpiece to estimate the inner diameter. The uncertainty of the measurement of the ring gauge is improved up to 140 nm
New dithienosilole- and dithienogermole- based BODIPY for solar cell applications.
No full textWe report two efficient donor materials for organic solar cells, namely Si- BDP and Ge- BDP, composed by the novel union of thienyl Bodipy wings and a dithienosilole/ dithienogermole core. These new donor molecules exhibited excellent solubility in organic solvents, extended p- conjugation and low- lying energy levels that matched with fullerene acceptors, supporting their application as donors in OSCs. Under optimized conditions and using PC70BM as an acceptor, desirable PCEs of 4.58% and 4.12% were observed for Si- BDP and Ge- BDP, respectively
A comparative investigation of pressure distortion coefficient of a pneumatic piston gauge and its associated uncertainty using varied approaches
No full textThis paper reports the evaluation of the measurement uncertainty of the pressure distortion coefficient () of a piston gauge using the Monte Carlo method (MCM) and its comparison with results obtained from the GUM (Guide to the expression of Uncertainty in Measurement) approach using the law of propagation of uncertainty. A reference pressure standard NPLI-4 was cross-floated against our pneumatic primary pressure standard NPLI-10, which is a large diameter piston gauge. The MCM was used for the simulated estimation. A good agreement is observed between the two methodologies, and the results are discussed in detail
Appearance of the persistently low tropopause temperature and ozone over the Bay of Bengal region
No full textThis paper reports the observation of persistently low tropopause temperatures (100hPa temperatures, T-100) and ozone at 100hPa throughout the year as compared to the corresponding zonal mean values over the Bay of Bengal (BOB) region. The long term mean T-100 (i.e., from January 2006-December 2009) over the BOB is similar to 2.2K lower than the zonal mean values over this region. The multiple linear regression analysis has been carried out to study the role of convection and ozone in giving rise to the persistently low T-100 over the BOB. Results show that the low ozone mixing ratios contributes similar to 1.2K and convection contributes similar to 0.35K to the persistently low T-100. The contribution of convection to the persistent low T-100 is mainly during the boreal monsoon season
A Study and analysis of stratum 1 set up establishment at NIC-NKN Delhi for IST synchronization of NKN network
Get PDFCSIR- National Physical Laboratory (CSIR-NPL) has set up stratum 1 services at two locations of NIC- NKN.
This paper explains the study and analysis of stratum 1 set up establishment at NIC-NKN Delhi for IST
synchronization of NKN networ
Comparative Charge Transport Study of MEHPPV-TiO2 and P3HT-TiO2 Nanocomposites for Hybrid Bulk Heterojunction Solar Cells
No full textTiO2 nanorods integrated with poly[2-methoxy, 5-(2-ethylhexyloxy)-p-phenylenevinylene] (MEHPPV) and poly(3-hexylthiophene) (P3HT) matrixes were investigated for charge transport properties to evaluate their potential application in a hybrid solar cell device. An exhaustive characterization was performed to identify the best hybrid nanocomposite among MEHPPV-TiO2 and P3HT-TiO2. The analysis involved optical and electrical characterization techniques such as the X-ray diffraction, field emission scanning electron microscope, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, photoluminescence, atomic force microscopy, X-ray photoelectron spectroscopy, and I-V measurements. TiO2 nanorods exhibited excellent dispersion in both polymer matrixes, thus significantly improving the photocurrent generation and net efficiency. Therefore, the overall device performance was improved. The findings of this study demonstrated that the P3HT-TiO2 photovoltaic device exhibited superior performance than the MEHPPV-TiO2 photovoltaic device. We believe that this evaluation would certainly contribute to the understanding of interfacial exciton dissociation in nanoscale morphology for the next-generation hybrid bulk heterojunction solar cells
Enhanced near-infrared luminescence in zinc aluminate bestowed by fuel-blended combustion approach
No full textFuel-blend combustion method using urea and monoethanolamine (MEA) fuels, is employed to tune the defect states and hence luminescence properties of nanocrystalline ZnAl2O4. Prepared nanocrystals flaunt a ravishing blue and intensified near-infrared (NIR) emission with varying intensities. Sample prepared using 80% MEA blended with 20% urea exhibits highest NIR emission, seven-fold intense than that prepared by 100% MEA, attributed to larger amount of deep band gap defects. Presence of multiple defects viz. vacancies of zinc, aluminium and oxygen is probed by means of Rietveld refinement, X-ray absorption near edge spectroscopy and photoluminescence spectroscopy. Band tailing and presence of shallow defect states are indicated by optical band gap and Urbach energy values. Broad range visible to NIR emission envisages application of ZnAl2O4 nanocrystals for bioimaging purposes. Radiative transitions among various defect levels contributing toward the emission have been depicted through a band model diagram
Optimization of a Piezoelectric Mechanical Amplifier Actuator for Nano-Indentation
Get PDFIn the present investigation, a piezo-stack actuator coupled with a flexible diamond shaped frame has been investigated for its mechanical amplification property. The piezo-stack under electrical excitation produces a longitudinal strain along major diagonal of the frame which gets amplified due to its diamond shape along the shorter diagonal. The effect of the thickness of flexural hinges used in the diamond frame on amplification has been studied with a view to optimize the stress and displacement. The effectiveness of the piezoelectric mechanical amplifier actuator as a nano-indenter has been studied and discussed in this paper
Nickel nanoparticles-super yellow (PDY-132) nanoblends for organic light emitting devices
No full textWe report the synthesis of nickel nanoparticles (NPs) by wet chemical route and its blend with emissive PDY-132(super yellow) matrix for application in Organic Light-Emitting Devices (OLEDs). Wet Chemical Synthesis allows the successful synthesis of CTAB (Cetyl Trimethyl Ammonium Bromide) capped nickel (Ni) nanoparticles having a size of 5-7 nm. The synthesized colloidal having nanoparticles can be easily mixed with emissive polymer solutions to obtain a blend for OLED application. From the experimental results, it is observed that turn on voltage decreases to 3.54V from 9V and current increases to 14mA from 4mA after adding Ni NPs into the emissive layer. The narrowing and sharpening of electroluminescence were observed
A Green Route Strategy for the Synthesis of Multifunctional Polymer Nanocomposites for Environmental Sustainability
No full textHerein, one-step green strategy is demonstrated for the synthesis of multifunctional polymer nanocomposite material using eco-friendly thiol-enephotopolymerization reaction at room temperature without use of any crosslinking agents. The greener route of thiol-ene click reaction results in the formation of extremely high functional groups incorporated crosslinked surface as the thiol groups are reacted with each double bond in the nanograpite network, which is difficult to obtain by any other conventional method. In an attempt to encounter with environmental issues, this facile nanocomposite material can not only detect organic vapor in air but also degrades organic pollutant and microorganisms in water. The response time obtained by thiol-ene functionalized nanocomposite (TE-f-NC) material is recorded as 6 seconds and the recovery is not more than 60 seconds towards formaldehyde vapors. The TE-f-NCs for detection of formaldehyde vapor will make a value-added ultimate product and their commercialization will directly benefit to the society. Moreover, the photocatalytic activity of the obtained TE-f-NC material for the degradation of methyl blue (MB) under UV irradiation source was investigated, and found more than 50% of the initial concentration of MB dye degraded within first 3 min using TE-f-NC (0.6%) polymer nanocomposite. Along with photocatalytic activity, It is worth pointing out that the hybrid material can be readily used for antimicrobial activity toward various pathogenic microbes depicting the growth inhibition of microorganism by disrupting the cell walls