Assessment of the Formant Frequencies in Normal and Laryngectomized Individuals Using Linear Predictive Coding

The objective of this study was to assess the difference in voice quality as defined by acoustical analysis using sustained vowel in laryngectomized patients in comparison with normal volunteers. This was designed as a retrospective single center cohort study. An adult tertiary referral unit formed the setting of this study. Fifty patients (40 males) who underwent total laryngectomy and 31 normal volunteers (18 male) participated. Group comparisons with the first three formant frequencies (F1, F2, and F3) using linear predictive coding (LPC) (Laryngograph Ltd, London, UK) was performed. The existence of any significant difference of F1, F2, and F3 between the two groups using the sustained vowel /i/ and the effects of other factors namely, tumor stage (T), chemoradiotherapy, pharyngectomy, cricothyroid myotomy, closure of pharyngoesophageal segment, and postoperative complication were analyzed. Formant frequencies F1, F2, and F3 were significantly different in male laryngectomees compared to controls: F1 (P<0.001, Mann-Whitney U test), F2 (P<0.001, Student's t test), and F3 (P=0.008, Student's t test). There was no significant difference between females in both groups for all three formant frequencies. Chemoradiotherapy and postoperative complications (pharyngocutaneous fistula) caused a significantly lower formant F1 in men, but showed little effect in F2 and F3. Laryngectomized males produced significantly higher formant frequencies, F1, F2, and F3, compared to normal volunteers, and this is consistent with literature. Chemoradiotherapy and postoperative complications significantly influenced the formant scores in the laryngectomee population. This study shows that robust and reliable data could be obtained using electroglottography and LPC in normal volunteers and laryngectomees using a sustained vowel.     

The thiazolium-catalyzed Sila-Stetter reaction: conjugate addition of acylsilanes to unsaturated esters and ketones

A new acyl anion addition reaction between acylsilanes and alpha,beta-unsaturated conjugate acceptors promoted by a nucleophilic organic catalyst has been disclosed. The 1,4-dicarbonyl products produced in this reaction are highly useful synthons. Neutral carbenes (or zwitterions) generated in situ from commercial thiazolium salts are used as effective catalysts for the reaction which is in contrast to established anionic catalysts typically employed to promote the required Brook rearrangement (1,2-silyl shift from carbon to oxygen) involved in the reported reaction. This process successfully utilizes acylsilanes as tunable acyl anion progenitors and is tolerant of a wide range of structural diversity on the acylsilane or the conjugate acceptor.     

Differential thermal and thermogravimetric analyses of bound water content in cellulosic substrates and its significance during cellulose hydrolysis by alkaline active fungal cellulases

Various cellulosic substrates were examined for bound water content by differential thermal analysis (DTA) and thermogravimetry (TG). Samples were heated in the range of 30-100 degrees C at a rate of 3 degrees C/min. DTA vaporization curves for different cellulose samples indicated that the bound water (Wf) was vaporized at higher temperature than free water (Wf) at the surface. Weight loss was observed in two stages, corresponding to Wf and Wb in TG curves. The bound water content was dependent on the degree of crystallinity of cellulose. Among different cellulosic substrates, Walseth cellulose showed the highest bound water content, and it also was found to be the least crystalline. The alkaline-active, alkali-stable cellulase was obtained from the alkalotolerant Fusarium sp. The substrate specificity and viscometric characteristics confirmed the enzyme to be an endoglucanase. The Wb content of Walseth cellulose was lowered during the enzymatic hydrolysis. The possible application of bound water analysis in understanding the hydrolysis of cellulosic substrates of different crystallinity is discussed.     

Asymmetric synthesis of functionalized trans-2,6-disubstituted piperidines with N-sulfinyl delta-amino beta-ketoesters. Synthesis of (-)-lasubine I

[reaction: see text] The hydroxy-directed reduction of 1,2-dehydropiperidines with the "ate" complex of DIBAL-H and n-BuLi affords functionalized trans-2,6-disubstituted piperidines. This methodology was employed in the asymmetric synthesis of the quinolizidine alkaloid (-)-lasubine I.     

Catalytic asymmetric synthesis of β-triazolyl amino alcohols by asymmetric transfer hydrogenation of α-triazolyl amino alkanones

The synthesis of optically active β-triazolyl amino alcohols was carried out via ruthenium catalyzed asymmetric transfer hydrogenation of α-triazolyl amino alkanones. This reaction proceeds under mild reaction conditions with up to 99% yield and 99.9% enantiomeric excess (ee). This protocol was applied to the synthesis of an enantiopure antitubercular agent and its arylated product with retention in enantiomeric purity. The absolute configuration at the stereogenic center of the chiral product as found to be (S).     

Electron spin resonance in pyrolyzed lignin

An investigation has been made into electron spin resonance (ESR) occurring in the ranges of carbons prepared from periodate lignin by vacuum pyrolysis. Line shape, line width, g-factors, saturation effects, and free spin concentration have been measured and the effect of oxygen on these parameters has been examined. A g-shift and lines with inhomogeneous broadening have been observed. In the presence of oxygen the lower-temperature carbons showed an unexpected increase in the detectable free spin concentration. The discussion includes factors affecting the nature of the free spins in the pyrolyzed material.     

Spectral and electrochemical investigation of 1,8-diaminonaphthalene upon encapsulation of p-sulfonatocalix[4]arene

The ligand salt, Me₆[14]diene·2HClO₄ (L·2HClO₄) was prepared by condensation of acetone and ethylene diamine in the presence of perchloric acid. On reduction of this diene ligand salt, L·2HClO₄ with sodium borohydride, the two isomeric ligands, ‘tet-a’ and ‘tet-b’ were produced. The ligands, on reaction with ZnX₂ (X=Cl, ClO₄, NO₃ or CH₃COO) and ZnSO₄ produced the corresponding complexes. These complexes have been characterized on the basis of elemental analyses; IR, UV–Vis and ¹H-NMR spectroscopies; magnetic and conductance data. Based on these data, all of the complexes of the diene ligand L, as well as the perchlorate complexes of all of the ligands attained a square-pyramidal arrangement, whereas the complexes of ‘tet-a’ and ‘tet-b’, with X=NO₃, Cl or CH₃COO and with ZnSO₄ salt, were octahedral. Moreover, all complexes were monometallic except the nitrato complex, [(ZnL)₂(µ-NO₃)](ClO₄)₃ which is bimetallic. The structure of [(ZnL)₂(µ-NO₃)](ClO₄)₃ has been confirmed by X-ray crystallography. In this complex the zinc centres lie within a N₄O donor set, with the four nitrogen donors from L and one of the oxygen atom stemming from the bridging NO₃. The complexes show different electrolytic behavior in different solvents. The antibacterial activities of the ligands and complexes towards different phytopathogenic bacteria have been investigated.     

Asymmetric Synthesis Using Sulfinimines (N-Sulfinyl Imines)

Abstract

Sulfinimine-derived polyfunctionalized chiral building blocks, often prepared in one pot, provide efficient access, with a minimum of chemical manipulation, to enantiopure, multifunctional amine derivatives including piperidines and pyrrolidines.     

Glutamine: fructose-6-phosphate amidotransferase (GFAT): homology modelling and designing of new inhibitors using pharmacophore and docking based hierarchical virtual screening protocol

Glutamine: fructose-6-phosphate amidotransferase (GFAT), also termed GFPT1 and GFAT1, catalyzes the first committed step of the hexosamine biosynthesis pathway in mammals and consequently plays an important role in type 2 diabetes. In the present study, a combination of pharmacophore modelling, homology modelling, and molecular docking analysis was performed to design new glutamine competitive inhibitors of human GFAT, and to investigate important interaction details of inhibitor molecules. A pharmacophore model of GFAT inhibitors was developed, subsequently validated, and utilized for the screening by the PHASE database to identify new molecules. Afterwards, homology modelling was performed to construct the glutamine-binding site of the GFAT protein. The modelled active site was utilized to dock the studied molecules to investigate important receptor-ligand interactions and to scrutinize database-screened molecules on the basis of essential interactions. This systematic in silico protocol helped us to identify new molecules that would be explored for the treatment of type 2 diabetes and its complications.