The structure and energetics of 3He and 4He nanodroplets doped with alkaline earth atoms

We present systematic results, based on density functional calculations, for the structure and energetics of 3He and 4He nanodroplets doped with alkaline earth atoms. We predict that alkaline earth atoms from Mg to Ba go to the center of 3He drops, whereas Ca, Sr, and Ba reside in a deep dimple at the surface of 4He drops, and Mg is at their center. For Ca and Sr, the structure of the dimples is shown to be very sensitive to the He-alkaline earth pair potentials used in the calculations. The 5s5p <-- 5s2 transition of strontium atoms attached to helium nanodroplets of either isotope has been probed in absorption experiments. The spectra show that strontium is solvated inside 3He nanodroplets, supporting the calculations. In the light of our findings, we emphasize the relevance of the heavier alkaline earth atoms for analyzing mixed 3He-4He nanodroplets, and in particular, we suggest their use to experimentally probe the 3He-4He interface.     

Analysis of Voice and Quantitative Measurement of Glottal Gap After Thyroplasty Type I in the Treatment of Unilateral Vocal Paralysis

Thyroplasty type I is one of several surgical treatments in which improving the voice of unilateral vocal fold paralysis is the ultimate objective. The goal of the surgery is the medialization of the paralyzed vocal fold. The purpose of this study is to evaluate the effectiveness of thyroplasty type I through acoustical analysis, aerodynamic measures, and quantitative videostroboscopic measurements. We report on 20 patients with unilateral vocal cord paralysis who underwent thyroplasty type I. We performed preoperative and postoperative video image analysis (normalized glottal gap area) and computer-assisted voice analysis (fundamental frequency, jitter, shimmer, noise-to-harmonic ratio, mean phonation time, mean flow rate, mean subglottic pressure) in all patients. The glottal gap was significantly reduced after thyroplasty type I. Postoperative voice quality was characterized by an improved pitch and amplitude pertubation (jitter and shimmer), phonation time (mean phonation time), and subglottic pressure (mean subglottic pressure). Thyroplasty type I is an effective method for regaining glottal closure and vocal function.     

Laryngeal Gestures During Stop Production Using High-Speed Digital Images

On acoustic and fiberscopic studies of stop consonants, voice onset time and glottal width have been shown to be greatest in heavily aspirated stops, next greater for slightly aspirated stops, and least for unaspirated stops. Integrated activity of the thyroarytenoid and posterior cricoarytenoid muscles has been reported to be involved in differentiating aspirate characteristics of the stops. However, the fine movement of mucosal edges of vocal folds during the production of stops has not been well documented. In recent years, a new method for high-speed digital recording of laryngeal dynamics has made this possible. In the current study, the movements of vocal fold edges were documented during the period of stop production using a fiberscopic system of high-speed digital images. By observing the glottal width and the visual vibratory movements of vocal folds before voice onset, the heavily aspirated stop was characterized as being more prominent and dynamic than the slightly aspirated and unaspirated stops.     

Hyaluronic Acid: Its Role in Voice

The extracellular matrix (ECM), once regarded simply as a structural scaffold, is now recognized as an important modulator of cellular behavior and function. One component that plays a prominent role in this process is hyaluronic acid (HA)--a molecule found in many different tissues. Research into the roles of HA indicates that it plays a key role in tissue viscosity, shock absorption, and space filling. Specifically, research into the role of HA in laryngology indicates that it has profound effects on the structure and viscosity of vocal folds. This article provides an introduction to the structure and biological functions of HA and its importance in voice. In addition, an overview of the pharmaceutical applications of HA is discussed.     

Vocal Nodules and Laryngeal Morphology

Our purpose was to study the occurrence of vocal fold nodules under conditions of habitual vocal abuse associated with increased laryngeal muscle tension, to identify the existence of a relationship between vocal nodules and laryngeal morphology. We studied one group of 30 subjects with vocal nodules, 18 to 50 years old, who were compared with two control groups, one of females and one of males, consisting of 30 subjects each. The parameters evaluated were: type of vocal folds coaptation, glottic proportion (GP) and abduction angle (AA), obtained by videotelelaryngoscopy. In the nodules group, the larynges presented a mean value of GP similar to that of the female group, both of which were lower than the mean GP value of the male group. On the other hand, the mean AA was lower than the one in the female group, and closer to the one in the male group. We concluded that vocal nodules were present only in larynges with a predominantly young female morphology, with functional limitations of abduction.     

A practical, one-pot synthesis of highly substituted thiophenes and benzo[b]thiophenes from bromoenynes and o-alkynylbromobenzenes

An efficient synthesis of thiophenes and benzo[b]thiophenes has been developed from easily available bromoenynes and o-alkynylbromobenzene derivatives. This novel one-pot procedure involves a Pd-catalyzed C-S bond formation using a hydrogen sulfide surrogate followed by a heterocyclization reaction. Moreover, in situ functionalization with selected electrophiles further expands the potential of this methodology to the preparation of the corresponding highly substituted sulfur heterocycles.     

Development of a solvent-free method for the simultaneous identification/quantification of drugs of abuse and their metabolites in environmental water by LC-MS/MS

This work details a rapid analytical method using direct sample injection for the simultaneous identification/quantification of 22 drugs of abuse, including some of their major metabolites, in environmental samples. This has been developed using a hybrid triple quadrupole-linear ion trap-mass spectrometer (QqLIT). With the increasing sensitivity of today's tandem mass spectrometers, direct injection analysis of water samples has become an attractive alternative to traditional analytical protocols, which often include a preliminary pre-concentration step. What's more, this kind of analysis is in accordance with many of the main objectives of so-called green analytical chemistry, or environmentally friendly practice. The analytical performance of the LC-MS/MS method was evaluated in three different water matrices (surface water, influent and effluent wastewater). Data acquisition was carried out in selected reaction monitoring (SRM) mode under time-scheduled conditions, monitoring two SRM transitions for simultaneous identification/quantification of all target compounds in the samples. Additionally, an experiment was performed using the information-dependent acquisition (IDA) scan to carry out the identification of those analytes for which the second transition was present at a low intensity. Finally, the two methodologies developed were applied to real samples for evaluation.     

Finite Tarski algebras are determined by their endomorphisms

We prove that if two finite Tarski algebras have isomorphic endomorphism monoids then they are isomorphic.     

Geometrothermodynamics of black holes

The thermodynamics of black holes is reformulated within the context of the recently developed formalism of geometrothermodynamics. This reformulation is shown to be invariant with respect to Legendre transformations, and to allow several equivalent representations. Legendre invariance allows us to explain a series of contradictory results known in the literature from the use of Weinhold’s and Ruppeiner’s thermodynamic metrics for black holes. For the Reissner–Nordström black hole the geometry of the space of equilibrium states is curved, showing a non trivial thermodynamic interaction, and the curvature contains information about critical points and phase transitions. On the contrary, for the Kerr black hole the geometry is flat and does not explain its phase transition structure.     

Fast domain wall dynamics in amorphous glass-coated microwires

Here we report on the domain wall dynamics in amorphous glass-coated FeCuNbSiB microwires measured in the temperature range from 77 up to 400 K. At low temperatures below 200 K, the domain wall velocity is proportional to the applied magnetic field. At temperatures above 200 K, two regions have been found: one with low domain wall mobility at low fields and another one with high domain wall mobility at high fields. The different regions of the domain wall dynamics are treated in terms of the change of the domain wall configuration from transversal to vortex one. Moreover, non-linear regime is shown at low fields at the temperature 373 K as a result of the domain wall interaction with the local defects.