National Physical Laboratory

About: National Physical Laboratory is a facility organization based out in London, United Kingdom. It is known for research contribution in the topics: Dielectric & Thin film. The organization has 7615 authors who have published 13327 publications receiving 319381 citations.

Comparative studies of pure BiFeO 3 prepared by sol–gel versus conventional solid-state-reaction method

Abstract: In this article, we studied the effect of synthesis route on the multifunctional properties of multiferroic BiFeO3. BiFeO3 powders were prepared by conventional solid-state-reaction and sol–gel route. X-ray diffraction (XRD) patterns for these samples were collected at different stages of synthesis to analyze the phase purity of the formation. The XRD patterns reveal that sample prepared by sol–gel route attains the low temperature phase formation as compared to the solid state route. Rietveld refinement has been performed for these samples and lattice parameters, cell volume bond length etc. have been calculated from XRD patterns. Phonon modes were studied by Fourier transform infrared spectroscopy measurements and bond length calculated from XRD shows the good agreement with the bond length calculated from IR spectra. UV–visible spectra showed that BFO nanoparticles exhibit absorption peak at wavelength ~521 nm and band gap is more for the sample prepared by sol–gel route than solid state. The room temperature (RT) magnetic hysteresis (M–H) curve shows the large value magnetization in the sample prepared by sol–gel route in comparison to the sample prepared by solid state route. Similar behaviour is seen in the P–E hysteresis curve. Room temperature dielectric properties of these samples revealed that there is dispersion in the low frequency range that shows normal dielectric characteristics.

Coimmobilization of urease and glutamate dehydrogenase in electrochemically prepared polypyrrole-polyvinyl sulfonate films.

Abstract: Immobilization of urease and glutamate dehydrogenase enzymes in electrochemically prepared polypyrrole-polyvinyl sulfonate films (PPY-PVS) was carried out using physical adsorption and electrochemical entrapment techniques. Detailed studies on optimum pH, Fourier transform infrared spectroscopy, cyclic voltammetry, and scanning electron microscopy of the enzymes in the immobilized state were conducted. The value of the apparent Michaelis-Menten constant was experimentally determined to be 2.5 and 2.7 for physically adsorbed and electrochemically entrapped urease in PPY-PVS films, respectively.

Ambient mass spectrometry: advances and applications in forensics

Abstract: Ambient surface mass spectrometry is a powerful and rapidly growing new field that provides high sensitivity mass spectrometry direct from surfaces at ambient pressure. There is now a rich evidence base in the published literature of the success of these methods for forensic analysis including: detection of explosives at ng levels; chemical composition of pharmaceutical tablets, drug detection from biological liquids such as urine and plasma; breath analysis of metabolites; imaging analysis for document verification and fingerprint identification. Recent developments in miniaturised (shoe box sized) mass spectrometers have enabled these developments to be translated to portable on-scene detection and first responder usage. In this review, we illustrate and compare the effectiveness of the most popular and promising techniques of Desorption Electrospray Ionisation (DESI), Direct Analysis in Real Time (DART), Plasma Assisted Desorption Ionisation (PADI) and Extractive Electrospray Surface Ionisation (EESI). Forensic analysis by its very definition must stand up to scrutiny in a court of law. It is therefore essential that measurements are repeatable, valid and fit for purpose. The establishment of a measurement infrastructure is therefore essential to ensure that the methods used may be accredited and conform to relevant quality systems and procedures