Using Raman Spectroscopy to Investigate the Molecular Level Characteristics of Endometriosis

Optics and Spectroscopy - Endometriosis is a benign gynecologic disorder. It is particularly common among young women and may make pregnancy difficult. In this study molecular level...     

Re-Evaluation of a Fulvene-Based Self-Replicating Diels–Alder Reaction System

We re-evaluate our claim of a high diastereoselectivity in the self-relicating Diels–Alder reaction between maleimide 1 and fulvene 3 . It was shown that the system has a diastereoselectivity of 1.8:1 for NN-4 : NX-4 , which is contrary to the 16:1 ratio claimed by Dieckmann et al. The analysis of ¹H NMR monitoring of the reaction revealed that both replicators show sigmoidal growth which is typical for auto-catalytic systems.     

Molecular Structure,Vibrational Spectra,Molecular Docking,and ADMET Study of Cellulose Triacetate II

Optics and Spectroscopy - People have started to look for alternative sources because of the health problems created by petrochemical products used in all areas of human life and environmental...     

Role of polydimethylsiloxane in properties of ternary materials based on polyimides containing zeolite Y

Mixed matrix materials, containing poly(dimethylsiloxane), phosphine oxide-based polyimide, and zeolite Y were prepared by means of blending hybridisation. The thermal stability of the materials and the hydrophobic properties were enhanced. The decrease in the glass transition temperature of the materials with the increase in poly(dimethylsiloxane) content supported the polymer-chain flexibility. The pristine polyimide and the zeolite-filled polyimide exhibited the highest transparency. Fourier transform infrared (FTIR) spectroscopy confirmed that the increase in the amount of the lowest molecular mass poly(dimethylsiloxane) ingredient indicated strong alkyl and Si-O-Si stretching modes, whilst the alkyl and Si-O-Si stretching intensity decreased in the presence of the highest amount of and the highest molecular mass poly(dimethylsiloxane). The hydrophobic poly(dimethylsiloxane) moiety created an inverse relationship between the porosity of the materials (surface roughness) and the hydrophilicity. The nanocrystallite domain, identified by X-ray diffraction analysis (XRD) and possessing an exotherm crystallisation peak, occurred in the lowest amount of poly(dimethylsiloxane) with the highest molecular mass-based hybrid material. The nanocrystallite enhanced the storage modulus as determined by the dynamic mechanical analyser (DMA). The nanocrystalline formation resulted in a slight increase in the alkyl stretching and the Si-O-Si stretching of the lowest amount of and the highest molecular mass poly(dimethylsiloxane)-containing material over those of the lowest molecular mass poly(dimethylsiloxane) in the same amounts of material involved.     

A proficiency test scheme for the quality control of black tea and development of quality control material for internal quality control

A proficiency test (PT) was organized for quality control analysis of black tea. Test materials for the analyses of total content of powder tea, moisture, total ash, acid-insoluble ash, water-soluble ash, alkalinity of water-soluble ash, water extract, crude fiber and caffeine were sent to the participant laboratories (n:43) in 2009. The assigned value, standard deviation of the parameters and z-scores of the participant laboratories were calculated using the data reported by the participants. The percentage of the reported results for analytes was found to be ranged from 67.5 to 100%. Acceptable z-scores were achieved by 80.5–97.5% of the participant laboratories. More than 15% of unacceptable results were obtained for acid-insoluble ash and caffeine analyses. The quality control material for quality control analysis of black tea was developed from the remaining material.     

IR spectroscopic studies on the transmission of substituent effects to carbonyl and thiocarbonyl stretching frequencies in 4-substituted phenyl-4,5-dihydrobenzo [f] [1,4] oxazepin-3 (2H)-ones (thiones)

Single and dual substituent correlation analysis were applied to study transmission of substituent effects on IR carbonyl and thiocarbonyl stretching frequencies of 4-substituted phenyl-4,5-dihydrobenzo [f] [1,4] oxazepin-3 (2H)-ones (5a–n) and -thiones (6a–n). The substituent effects were estimated on the basis of results of the statistical analysis. The differences among the regression coefficients were discussed in terms of the relative importance of the substituent field and resonance effects. For a better understanding of the results, density functional theory (DFT) calculations were performed to determine the preferred geometry and to calculate the theoretical carbonyl and thiocarbonyl stretching frequencies.     

Novel anhydrous proton conducting copolymers of 1‐vinyl‐1,2,4‐triazole and diisopropyl‐p‐vinylbenzyl phosphonate

Phosphonic acid functional polymers are currently of interest because of their high proton conductivity in humidified and anhydrous systems. In addition, heterocyclic compounds are used in anhydrous proton conducting polymer membranes. In that study, a new copolymer based on 1‐vinyl‐1,2,4‐triazole (VTri) and diisopropyl‐p‐vinylbenzyl phosphonate (VBP) was synthesized, and their thermal, chemical, and proton conducting properties were investigated. The copolymers were synthesized by free radical copolymerization of the corresponding monomers at several monomer feed ratios to obtain P(VTri‐co‐VBP) copolymers. The copolymer samples were then hydrolyzed to produce poly(vinyl triazole‐co‐vinyl phosphonic acid) copolymers. The composition of the copolymers was determined by elemental analysis. The copolymerization and hydrolysis reactions were verified by Fourier transform infrared spectroscopy and ion exchange capacity measurements. Thermogravimetry analysis indicates that the copolymers are thermally stable up to 300°C. In order to increase the proton conductivity, the copolymers were doped with H₃PO₄ at several stoichometric ratios. The proton conductivity increases with triazole and phosphoric acid content. In the absence of humidity, the copolymer electrolyte, P(VTri‐co‐VBPA)1:0.5 X = 2, showed a proton conductivity of 0.005 S/cm at 150°C. Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis and proton conductivity studies of polystyrene‐based triazole functional polymer membranes

In this study, poly(vinylbenzylchloride) (PVBC) was produced by free‐radical polymerization of 4‐vinylbenzylchloride, and then it was functionalized with 3‐amino‐1,2,4‐triazole (ATri) and 1H‐1,2,4‐triazole (Tri). The composition of the polymers was verified by elemental analysis, and the structure was characterized by Fourier transform infrared and ¹³C‐nuclear magnetic resonance spectra. PVBC was modified by ATri with 68% and Tri with 50% yield. The polymers were doped with trifluoromethanesulfonic acid (TA) at various molar ratios, X = 0.5, 1, 2, and 3 with respect to aminotriazole and triazole units. Proton transfer from TA to the triazole rings was proved with Fourier transform infrared spectroscopy. Thermogravimetric analysis showed that the samples are thermally stable up to approximately 200 °C. Differential scanning calorimetry results illustrated the homogeneity of the materials. Under anhydrous conditions, PVBCATri3TA and PVBCTri3TA showed highest proton conductivity of 0.086 and 0.042 S/cm, respectively. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Synthesis and proton conductivity studies of azole functional organic electrolytes

As an attempt to produce azole functional proton conductors, organic electrolytes with triazole and tetrazole functional groups were synthesized via substitution reaction of 1,3,5-benzenetricarbonyl trichloride with aminotriazole and aminotetrazole. The samples were doped with triflic acid with molar ratios of 0.25 and 0.50. FTIR, nuclear magnetic resonance (NMR), and elemental analysis were used to characterize the resulting materials. Thermogravimetric analysis showed that the samples are thermally stable up to 150?°C. The effect of acid doping on proton conductivity was investigated with impedance spectrometer. Both pure samples and the doped ones revealed high proton conductivity. In anhydrous conditions (TMA)-TriTA_0.50 and TMA-TetTA_0.50 have proton conductivities of 1.8 and 19?mS/cm at 150?°C, respectively. Solid-state NMR studies revealed that there are three different types of hydrogen-bonded acidic proton in the systems. Moreover, these different types of acidic protons present at different ratio in triazole and tetrazole systems.