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41.
MK Bhide RM Kadam MD Sastry Ajay Singh Shashwati Sen Manmeet Kaur DK Aswal SK Gupta VC Sahni 《Pramana》2002,58(5-6):799-802
Microwave absorption studies have been carried out on MgB2 superconductor using a standard X-band EPR spectrometer. The modulated low-field microwave absorption signals recorded for
polycrystalline (grain size ∼ 10 μm) samples suggested the absence of weak-link character. The field dependent direct microwave
absorption has been found to obey a ✓H dependence with two different slopes, which indicated a transition from strongly pinned lattice to flux flow regime. 相似文献
42.
The action of 1,10-phenanthroline (phen) on the THF solutions of RHgCl (R = 2,5-C6H3Cl2; 2,3,4? and 2,4,6-C6H2Cl3; 2,3,4,5?, 2,3,4,6?, and 2,3,5,6-C4HCl4 and C6Cl5) gives RHgCl (phen) when R contains two chlorine substituents in ortho (R = 2,4,6-C6H2Cl3; 2,3,4,6?, and 2,3,5,6-C6HCl4 and C6Cl5), but the symmetrisation reaction occurs when R = 2,5-C6H3Cl2; 2,3,4-C6H2Cl3 and 2,3,4,5-C6HCl4. The action of phen on HgR2 only gives HgR2 (phen) when R = 2,3,4,5-C6HCl4. Compounds of the type RHgMe do not react with phen. These results indicate that steric citects are as important as the electronegativity of R in the formation of tetracoordinated mercury compounds. 相似文献
43.
Analysis of Voice and Quantitative Measurement of Glottal Gap After Thyroplasty Type I in the Treatment of Unilateral Vocal Paralysis 总被引:2,自引:0,他引:2
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. 相似文献
44.
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. 相似文献
45.
Hyaluronic Acid: Its Role in Voice 总被引:8,自引:0,他引:8
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. 相似文献
46.
Paulo Pontes MD Leny Kyrillos Mara Behlau Noemi De Biase Antonio Pontes 《Journal of voice》2002,16(3):408-414
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. 相似文献
47.
Olliges-Stadler I Stötzel J Koziej D Rossell MD Grunwaldt JD Nachtegaal M Frahm R Niederberger M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(8):2305-2312
Insight into the complex chemical mechanism for the formation of tungstite nanoparticles obtained by the reaction of tungsten hexachloride with benzyl alcohol is presented herein. The organic and inorganic species involved in the formation of the nanoparticles were studied by time-dependent gas chromatography and X-ray diffraction as well as by time-resolved in situ X-ray absorption near-edge structure and extended X-ray absorption fine structure spectroscopy. Principal component analysis revealed two intermediates, which were identified as WCl(4) and WOCl(4) by using linear combination analysis. Quick-scanning extended X-ray absorption fine structure spectroscopy enabled the time-dependent evolution of the starting compound, the intermediates and the product to be monitored over the full reaction period. The reaction starts with fast chlorine substitution and partial reduction during the dissolution of the tungsten hexachloride in benzyl alcohol followed by the generation of intermediates with W=O double bonds and finally the construction of the W-O-W network of the tungstite structure. 相似文献
48.
Inma Angurell Dr. Oriol Rossell Prof. Miquel Seco Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(12):2932-2940
Onion structures : Carbosilane dendrimers containing up to four metal layers have been constructed (see picture). The metal layers are linked by di‐ or tritopic N,P ligands. Selective deconstruction of the dendrimers is achieved by using salts of chloride or iodide anions.
49.
A. S. Ahmad MD N. Hoda M. Ahmad F. Islam S. Z. Qureshi 《Journal of Analytical Chemistry》2006,61(9):870-874
A simple, sensitive, and selective kinetic spectrophotometric method for the determination of kanamycin in pure form and pharmaceutical
formulations is described. The method is based on the measurement of the intensity of the yellow chromogen formed by the reaction
between kanamycin and acetylacetone-formaldehyde reagent in a N,N′-dimethyl formamide medium. The variable-time method was used to evaluate the rate of reaction of the colored chromogen formed
at 410 nm. The reaction conditions were optimized and the calibration graph was found to be linear in the range 60–160 μg/mL.
The results obtained by the developed and reference methods are in good agreement. Various statistical parameters were evaluated
to establish the precision, accuracy, repeatability, and reproducibility of the proposed method.
The text was submitted by the authors in English. 相似文献
50.
H.J. Rossell 《Journal of solid state chemistry》1979,27(1):115-122
The crystal structures of the orthorhombic fluorite-related compounds La3NbO7 (Cmcm), Y3TaO7, and Y2GdSbO7, (C2221) have been determined from X-ray powder diffraction intensities and single-crystal electron diffraction data. The structures are basically similar. One third of the Ln cations are 8-coordinated, and lie in [001] rows which alternate with parallel rows of corner-linked MO6 coordination octahedra within slabs parallel to (100). The remaining Ln cations lie in between these slabs in seven-fold coordination. This interslab cation arrangement distinguishes the structure from the closely related pyrochlore (A2B2O7) and weberite (Na2MgAlF7) structures. The compounds YGdScSbO7 and Nd2ScNbO7, also examined, have the pyrochlore structure, with Sc and Sb, or Sc and Nb distributed on the octahedral B sites. 相似文献