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.     

Comparison of a high‐performance liquid chromatography method for quantification of carbamazepine with chemiluminescent microparticle immunoassay

Carbamazepine is an antiepileptic drug widely used for the treatment of epilepsy. In the National Institute of Neurology, monitoring has been performed using the technique chemiluminescent microparticle immunoassay (CMIA) in an automated way during the last five years. The aim of this study was to develop a simple and rapid HPLC analytical method coupled to DAD‐UV detection for the determination of plasma concentrations of carbamazepine and compare its feasibility with those used in routine analysis. The developed HPLC method was fully validated and the applicability of the proposed method was verified through the analysis of plasma samples of patients and later compared with the quantification of the same plasma samples with the CMIA method. The limit of quantification obtained was 0.5 μg/mL. The mean value for recovery was 99.05% and the coefficient of variation (CV) was 5.6%. The precision and accuracy of this method were within the acceptable limits; inter‐ and intraday CV values were <10%. The correlation between the CMIA method and the developed HPLC method was very good (r ≈ 0.999). A Bland–Altman plot showed no significant bias between the results. The HPLC‐DAD method may be an alternative to determine and monitoring the carbamazepine levels in human plasma or serum. Copyright © 2015 John Wiley & Sons, Ltd.     

Information-theoretical complexity for the hydrogenic identity S N 2 exchange reaction

We investigate the complexity of the hydrogenic identity S _N 2 exchange reaction by means of information-theoretic functionals such as disequilibrium (D), exponential entropy (L), Fisher information (I), power entropy (J) and joint information-theoretic measures, i.e., the I–D, D–L and I–J planes and the Fisher–Shannon (FS) and López-Mancini-Calbet (LMC) shape complexities. The several information-theoretic measures of the one-particle density were computed in position (r) and momentum (p) spaces. The analysis revealed that the chemically significant regions of this reaction can be identified through most of the information-theoretic functionals or planes, not only the ones which are commonly revealed by the energy, such as the reactant/product (R/P) and the transition state (TS), but also those that are not present in the energy profile such as the bond cleavage energy region (BCER), the bond breaking/forming regions (B–B/F) and the charge transfer process (CT). The analysis of the complexities shows that the energy profile of the identity S _N 2 exchange reaction bears no simple behavior with respect to the LMC and FS measures. Most of the chemical features of interest (BCER, B–B/F and CT) are only revealed when particular information-theoretic aspects of localizability (L or J), uniformity (D) and disorder (I) are considered.     

Nanocap-shaped tin phthalocyanines: synthesis, characterization, and corrosion inhibition activity

Thermal and microwave reactions between [PcSn(IV)Cl2] (1) and the potassium salts of eight fatty acids (2 a-h) led to cis-[(RCO2)2Sn(IV)Pc] compounds (3 a-h) in yields ranging from 54 to 90 %. Compounds 3 a-h were fully characterized by elemental analysis, spectroscopy (IR, UV/Vis, multinuclear NMR), and seven X-ray diffraction structures, whereby two different allotropes were observed in two cases. The two carboxylates in 3 have a cis anisobidentate binding mode, octacoordination of the tin atoms with square-antiprismatic geometry, and pi-electron-rich nanocap shapes. On account of the latter characteristics, 3 a-h compounds have anticorrosion properties. LPR and Tafel electrochemical methods were used to characterize the behavior of these derivatives in naturally aerated sour brine, which is a common environment in petroleum production and refinery operations. The measurement of the corrosion rate of carbon steel AISI 1018 in the presence of 3 a-h (500 ppm) gave efficiencies of 61-87 % for the inhibitor performance. Of the different derivatives examined, compounds 3 e and 3 h were the most effective corrosion inhibitor prototypes.     

Shake-up satellites in x-ray photoelectron (ESCA) spectra of 5f0 Th(IV) compounds

X-ray photoelectron (ESCA) spectra of the Th 4f levels have been recorded in 12 Th compounds. Weak satellites are observed in all the 4f spectra at binding energies 4–6 eV from the primary photolines. On the basis of a multiple scattering calculation in ThO₂, these satellites are assigned to ligand (e.g. O 2p) to Th 5f shake-up transitions. As with La 3d satellites, the satellite intensities correlate well with the nephelauxetic order of ligands.     

Rearranged icetexane diterpenoids from the roots of Salvia thymoides (Labiatae)

From the roots of Salvia thymoides Benth., three new rearranged icetexane diterpenoids (2-4) were isolated together with the previously described quinone tilifolidione (1). The proposed structures were established by extensive NMR analysis, including HMBC and HMQC pulse sequences.     

Ingested and biomineralized magnetic material in the prey Neocapritermes opacus termite: FMR characterization

The temperature dependence of Ferromagnetic Resonance spectra, from 5K to 280K, was used to study the magnetic material present in Neocapritermes opacus termite, the only prey of the Pachycondyla marginata ant. The analysis of the resonant field and peak-to-peak linewidth allowed estimating the particle diameters and the effective anisotropy energy density, K(EFF), as a sum of the bulk and surface contributions. It allowed to magnetically distinguish the particles of termites as collected in field from those of termites after 3 days under a cellulose diet, introduced to eliminate ingested/digested material. The data also, suggest the presence of oriented magnetite nanoparticles with diameters of 11.6+/-0.3nm in termites as collected in field and (14.0+/-0.4nm) in that under a cellulose diet. Differences between their K(EFF) and its components are also observed. Two transitions are revealed in the resonant field temperature dependence, one at about 50K that was associated to surface effects and the other at about 100K attributed to the Verwey transition.     

Jensen-Shannon divergence in conjugate spaces: The entropy excess of atomic systems and sets with respect to their constituents

The disorder of a composite system or of a set of different systems is always higher than the mere sum of the internal disorder of its constituents. One of the most widely used functionals employed for measuring the randomness of a single distribution is the Shannon entropy, from which the increase of disorder within the composite system with respect to those of the constituents is quantified by means of the Jensen-Shannon Divergence (JSD). In this work two different applications of the JSD in the study of the information content of atomic electron densities are carried out: (i) finding the contribution for a given atom of its composing subshells to the total atomic information; (ii) and similarly for selected sets of atoms, such as periods and groups throughout the Periodic Table as well as isoelectronic series. In both cases, the analysis is performed in the two conjugate position and momentum spaces, and the results are interpreted according to physically relevant quantities such as the ionization potential.