Modelling and simulation of the operation of a calorimetric sensor for medical application

Journal of Thermal Analysis and Calorimetry - In this study, the crystallization process in a directional solidification furnace is studied by using the transient numerical simulation. The flow...     

Quantum Bianchi Type IX Cosmology in K-Essence Theory

We use one of the simplest forms of the K-essence theory and apply it to the anisotropic Bianchi type IX cosmological model, with a barotropic perfect fluid modeling the usual matter content. We show that the most important contribution of the scalar field occurs during a stiff matter phase. Also, we present a canonical quantization procedure of the theory which can be simplified by reinterpreting the scalar field as an exotic part of the total matter content. The solutions to the Wheeler-DeWitt equation were found using the Bohmian formulation Bohm (Phys. Rev. 85(2):166, 1952) of quantum mechanics, employing the amplitude-real-phase approach Moncrief and Ryan (Phys. Rev. D 44:2375, 1991), where the ansatz for the wave function is of the form Ψ(? ^μ )=χ(?)W(? ^μ ) \(e^{- S(\ell ^{\mu })},\) , where S is the superpotential function, which plays an important role in solving the Hamilton-Jacobi equation.     

Quintom Potentials from Quantum Cosmology Using the FRW Cosmological Model

We construct the quintom potential of dark energy models in the framework of spatially flat Friedmann–Robertson Walker universe in the inflationary epoch, using the Bohm like approach, known as amplitude-real-phase. We find some potentials for which the wave function of the universe is found analytically and we have obtained the classical trajectories in the inflation era.     

Injection effect on the sensitivity in an isothermal titration calorimeter

By using electrical calibrations and with the injection of liquids with very different heating capacities (water and cyclohexane), it is made a thorough evaluation of the ‘injection effect’ in terms of the parameter ρc _p f (ρc _p – volumetric heat capacity, f – injection flow) in an isothermal titration calorimeter. This effect can be evaluated accurately in the case of non-volatile liquids, however, when dealing with volatile liquids, the uncertainty in their determination increases because of the vaporization heat.     

Amperometric determination of acetylsalicylic acid in drugs by batch injection analysis at a copper electrode in alkaline solutions

This paper describes the determination of acetylsalicylic acid (ASA) as salicylate (SA) in pharmaceutical formulations by using amperometric detection with copper electrodes in 0.10 mol l(-1) NaOH solution. Batch injection analysis (BIA) was explored for this application. The system exhibited sharp current response peaks, rapid washout and excellent repeatability. A large linear dynamic range from 1 to 1000 mumol l(-1) was obtained by using an injected volume of 100 mul, with a detection limit of 0.48 mumol l(-1). R.S.D. of 0.37% for 30 repetitive (1x10(-4) mol l(-1)) injections and sampling frequency of 60 h(-1) were achieved. The results obtained using this system for ASA determination in seven different drug samples compared well with those found by spectrophotometry (Trinder test).     

Ring-Opened Adducts of the Anticancer Drug Carboplatin with Sulfur Amino Acids

Reactions of the anticancer drug carboplatin ("Paraplatin") with a variety of sulfur-containing amino acids have been investigated by (1)H and (15)N NMR spectroscopy and by HPLC. Thiols react very slowly and sulfur-bridged species containing four-membered Pt(2)S(2) rings are the predominant products. In contrast, reactions with thioether ligands are much more rapid, and kinetics for the initial stages of the reaction with L-methionine have been determined (k = 2.7 x 10(-)(3) M(-)(1) s(-)(1)). Surprisingly, very stable ring-opened species are formed such as cis-[Pt(CBDCA-O)(NH(3))(2)(L-HMet-S)] which has a half-life for Met-S,N ring-closure of 28 h at 310 K. A study of the formation of the analogous product for N-acetyl-L-methionine and its subsequent ring closure is reported. Reactions such as these may play a role in the biological activity of carboplatin.     

Digital holographic interferometry applied to the study of tympanic membrane displacements

Quantitative studies of the mechanical properties of tympanic membrane (TM) are needed for better understanding of its role in detailed clinical evaluation, its research being of extreme importance because it is one of the most important structures of the middle ear. By finding the membrane's vibration patterns and quantifying the induced displacement it is possible to characterize and determine its physiological status. Digital holographic interferometry (DHI) has proved to be a reliable optical non-invasive and full-field-of-view technique for the investigation of different mechanical parameters of biological tissues, i.e., DHI has demonstrated an ability to detect displacement changes in quasi-real time and without the need to contact the sample's surface under study providing relevant information, such as clinical and mechanical sample properties. In this research fresh tympanic membrane specimens taken from post-mortem cats are subjected to acoustic stimuli in the audible frequency range producing resonant vibration patterns on the membrane, a feature that results in an ideal application for DHI. An important feature of this approach over other techniques previously used to study the tympanic membrane vibrations is that it only requires two images and less hardware to carry out the measurements, making of DHI a simpler and faster technique as compared to other proposed approaches. The results found show a very good agreement between the present and past measurements from previous research work, showing that DHI is a technique that no doubt will help to improve the understanding of the tympanic membrane's working mechanisms.     

Flow microcalorimetry and thermokinetics of liquid mixtures

The identification of the calorimetric curves corresponding to liquid mixtures for different injection flows, given by a flow microcalorimeter, permits to classify in a kinetic way the studied mixtures. For this purpose, it is determined the establishment time constant of the mixture (τ_mix) that allows us to estimate the length occupied by the dissipation (through the parameter λ_mix) and thus to justify the sensitivity variation obtained in different chemical calibrations.