Scanning Electron Probe Microanalysis

Scanning electron probe microanalysis has grown over the pastthree decades into a powerful technique for the microchemicalcharacterisation of materials. This paper describes the principles andvarious features of a typical microanalyser, and illustrates its uniquecapabilities in the study of materials by means of selected case histories

Sequential sporadic-E layers at low latitudes in the Indian sector

International audienceA study of the formation and movement of sequential Sporadic-E layers observed during the night-time hours at two Indian low-latitude stations, SHAR (dip 10°N) and Waltair (dip 20°N) shows that the layer are formed around 19:00 h. IST at altitudes of ~180 km. They descend to the normal E-region altitude of about 100 km in three to four hours and becomes blanketing type of Es before they disappear. However, the absence of these descending layers at an equatorial station, Trivandrum (dip 2°N) gives the experimental evidence for wind shear theory. The meridional neutral wind derived from the height variation of the F-layer showed significant poleward wind during the descent of these layers. Hence it is inferred that these layers are formed as a consequence of the convergence of plasma by the poleward wind and the equatorward propagating gravity waves (inferred from the height fluctuations of F-layer)

Transient isomerisation and inverse electronic relaxation of infrared multiple-photon excited Pentafluoropyridine

Pentafluoropyridine (PFP) undergoes fast structural isomerisation to fulvenes when irradiated with 9R(16) CO2 laser line in the fluence range 0.5-1.5 J/cm2. The unstable fulvenes slowly decay back to PFP in ms time scale. No detectable permanent dissociation of PFP was observed in the above low fluence experiments. However, by using focused CO2 laser beam for the irradiation of PFP, an emission of light in the visible/near-UV was observed. The time evolution of the luminescence reveals three peaks at 390, 460 and 500 nm on a broad background emission of 300-680 nm. These bands are assigned to the fluorescence of PFP via inverse electronic relaxation (IER) and C2 Swan bands. On prolonged irradiation of PFP in focused condition a small extent of permanent dissociation was observed with the major products as C2F4, a sooty yellow deposit and another compound presumed to be Dewar PFP

HYDROGEL: RESPONSIVE STRUCTURES FOR DRUG DELIVERY

Hydrogels are water-swollen 3D networks made of polymers, proteins, small molecules, or colloids. They are porous in structure and entrap/encapsulate large amounts of therapeutic agents and biopharmaceuticals. Their unique properties like biocompatibility, biodegradability, sensitivity to various stimuli, and the ability to be easily conjugated with hydrophilic and hydrophobic drugs with a controlled-release profile make hydrogels a smart drug delivery system. Smart hydrogel systems with various chemically and structurally responsive moieties exhibit responsiveness to external stimuli including temperature, pH, ionic concentration, light, magnetic fields, electrical fields, and chemical and biological stimuli with selected triggers includes polymers with multiple responsive properties have also been developed elegantly combining two or more stimuli-responsive mechanisms. This article emphasized the types, features, and various stimuli systems that produce responsive delivery of drugs

Characteristics of VHF radiowave scintillations over a solar cycle (1983?1993) at a low-latitude station: Waltair (17.7°N, 83.3°E)

International audienceThe characteristics of VHF radiowave scintillations at 244 MHz (FLEETSAT) during a complete solar cycle (1983?93) at a low-latitude station, Waltair (17.7°N, 83.3°E), are presented. The occurrence of night-time scintillations shows equinoctial maxima and summer minima in all the epochs of solar activity, and follows the solar activity. The daytime scintillation occurrence is negatively correlated with the solar activity and shows maximum occurrence during the summer months in a period of low solar activity. The occurrence of night-time scintillations is inhibited during disturbed days of high solar activity and enhanced during low solar activity

Selective IR laser chemistry of CDF<SUB>3</SUB> in natural fluoroform

Selective decomposition of CDF3 at natural abundance level (&#8776;150ppm) in fluoroform has been achieved by infra-red multiple-photon excitation at moderate substrate pressure using 100 ns FWHM CO2 laser pulses. Effects of energy fluence, number of laser pulses, buffer gas pressure and substrate pressure on decomposition yield and bulk selectivity are reported and discussed

A Comprehensive Survey of Convolutional Neural Networks for Skin Cancer Classification and Prediction

Skin cancer, a prevalent and potentially fatal condition, requires early detection and precise classification to ensure effective treatment. In recent years, there has been a significant rise in the popularity of Convolutional Neural Networks (CNNs) prominence as a robust solution for image processing and analysis, significantly surpassing conventional techniques in skin cancer prediction and classification. This survey paper offers a thorough examination of CNNs and their diverse applications in diagnosing skin cancer, emphasizing their benefits, existing obstacles, and potential avenues for future research