Polymerization by phase transfer catalysis. 24. Synthesis of condensation polymers derived from halogenated diphenol-amides with the amide group in the side chain

SUMMARY Poly(amide-ester)s, poly(amide-carbonate)s and poly(amide-thiocarbonate)s derived from the diphenols-amides N-(2,6-dibromo-4-nitrophenyl)-4,4-bis(4-hydroxyphenyl)-pentanamide (I) and N-(2,6-diiodo-4-nitrophenyl)-4,4-bis(4-hydroxyphenyl)-pentanamide (II) and terephthaloyl chloride (a), isophthaloyl chloride (b), and adipoyl chloride (c), and phosgene (d) and thiophosgene (e) respectively, have been synthesized under phase transfer conditions using several quaternary ammonium salts as phase transfer catalysts. Benzyltriethylammonium chloride (BTEAC) was effective in practically all cases due to the hydrophilicity of this catalyst. Poly(amido-ester)s derived from II and aromatic diacids were insoluble in all the organic solvents, and the effectivity of the process was evaluated by the increase of the yields with respect to the essays without catalysts. Received: 26 January 1999/Revised version: 17 May 1999/Accepted: 17 May 1999     

Structural symmetry breaking of silicon‐containing poly(amide‐imide) oligomers and its relation to electrical conductivity and Raman‐active vibrations

Optically active poly(amide‐imide) oligomers were synthesized by direct polycondensation between an aromatic diamine and a dicarboxylic acid both containing a diphenylsilylene unit. The reaction was carried out using triphenyl phosphite/pyridine in the presence of CaCl₂ and N‐methyl‐2‐pyrrolidone as solvent. Oligomers were obtained in good yields and showed high solubility in common aprotic polar solvents. The precursors, monomers and poly(amide‐imide) oligomers were characterized using elemental analysis and Fourier transform infrared and NMR (¹H, ¹³C, ²⁹Si) spectroscopy. Additionally, the main vibrations of the functional groups (C?O, C?C or N? H) in the oligomers with respect to temperature were characterized using Raman spectroscopy. The glass transition temperature was determined by studying the Raman spectra and corroborated using differential scanning calorimetry. The thermal stability was studied using thermogravimetric analysis. The molecular mass of the compounds was obtained from matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry and their optical properties were analyzed using UV‐visible diode array spectrophotometry. The electronic properties of the oligomers as well as the delocalization of charge carriers within their structures were analyzed using conductance‐voltage curves, which showed that these materials are excellent candidates for integrated optoelectronic applications. Copyright © 2011 Society of Chemical Industry     

Polymeric thin films of controlled complex refractive index formedby the electrostatic self-assembled monolayer process

This letter reports a method, the electrostatic self-assembled monolayer process, for the synthesis of multilayer thin-film materials with controlled complex refractive index. By incorporating appropriate precursor molecules in each monolayer and organizing the physical order of the multiple monolayers through the material, it is possible to achieve designed complex refractive index properties. In this work, the real part of the refractive index of materials formed by this process was controlled from 1.424 to 1.615, and the imaginary part was controlled from 0.00001 to 0.035, both at a wavelength of 550 nm. To our knowledge, this is the first time that experimental measurements of self-assembled thin films are presented to demonstrate that this method is useful for the design and synthesis of thin films of controllable refractive index     

In vitro and in vivo inhibition of Hass avocado polyphenol oxidase enzymatic browning by paeonol, β-cyclodextrin,and paeonol:β-cyclodextrin inclusion complex

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Assessment of production efficiency,physicochemical properties and storage stability of spray-dried propolis,a natural food additive,using gum Arabic and OSA starch-based carrier systems

The aim of this work was to obtain propolis in a powder, alcohol-free, water-dispersed and shelf-stable form. Propolis extract was spray-dried using gum Arabic and octenyl succinic anhydride (OSA) starch as carriers in two different weight ratios (1:4 and 1:6). Spray-dried propolis samples were evaluated for morphology, moisture, water activity, water dispersibility, hygroscopicity, particle size, particle distribution, entrapping efficiency, stability, isotherms and antioxidant properties. The spray-drying process produced round particles with sizes ranging from 15 to 24 μm. This process preserved the antioxidant activity of propolis and also allowed propolis to be obtained in a powder form, which was stable during storage at room temperature, had low hygroscopicity and was highly dispersible in cold water. The application of this technology could increase the use of propolis in various industrial applications, such as an antimicrobial and as an antioxidant in food.     

Mapping and characterization of novel (CAG)n repeat cDNAs from adult human brain derived by the oligo capture method

BACKGROUND: The role of chest CT scan in the assessment of patients with hemoptysis is uncertain. AIM: To evaluate the usefulness of CT scan in patients with non massive hemoptysis. PATIENTS AND METHODS: Ninety six patients, 60 male, aged 23 to 76 years old, who presented with hemoptysis to an University Hospital, were studied. All patients were studied with a chest radiograph, a fiberoptic bronchoscopy and a high resolution CT scan. RESULTS: The final causes of hemoptysis were bronchiectasis in 27 cases, bronchogenic carcinoma in 24 cases and lung infections in nine. The source of bleeding was not identified in 18 patients (19%). CT scan clarified abnormalities seen in the chest radiograph in 30 patients (31%) and provided new diagnostic information in 13 (14%). CT scan correctly localized the source of bleeding found by fiberoptic bronchoscopy in 35 of 43 patients (81%), whereas chest radiograph did so in 27 (77%). All patients with bronchogenic carcinoma were identified by chest radiograph or bronchoscopy. Twenty of the 27 patients with bronchiectasis had radiological abnormalities in the chest radiograph. In only two patients, with lung metastases and non conclusive chest radiograph and bronchoscopy, CT scan provided information that significantly modified clinical management. CONCLUSIONS: CT scan was useful to stage patients with bronchogenic carcinoma and to assess the extension of bronchiectasis, but its impact in the management and clinical evolution of patients was limited. Therefore we do not recommend the routine use of CT scan in the assessment of patients with hemoptysis.     

Substantial narrowing of the Niemann-Pick C candidate interval by yeast artificial chromosome complementation

Niemann-Pick disease type C (NP-C) is an autosomal recessive lipidosis linked to chromosome 18q11-12, characterized by lysosomal accumulation of unesterified cholesterol and delayed induction of cholesterol-mediated homeostatic responses. This cellular phenotype is identifiable cytologically by filipin staining and biochemically by measurement of low-density lipoprotein-derived cholesterol esterification. The mutant Chinese hamster ovary cell line (CT60), which displays the NP-C cellular phenotype, was used as the recipient for a complementation assay after somatic cell fusions with normal and NP-C murine cells suggested that this Chinese hamster ovary cell line carries an alteration(s) in the hamster homolog(s) of NP-C. To narrow rapidly the candidate interval for NP-C, three overlapping yeast artificial chromosomes (YACs) spanning the 1 centimorgan human NP-C interval were introduced stably into CT60 cells and analyzed for correction of the cellular phenotype. Only YAC 911D5 complemented the NP-C phenotype, as evidenced by cytological and biochemical analyses, whereas no complementation was obtained from the other two YACs within the interval or from a YAC derived from chromosome 7. Fluorescent in situ hybridization indicated that YAC 911D5 was integrated at a single site per CT60 genome. These data substantially narrow the NP-C critical interval and should greatly simplify the identification of the gene responsible in mouse and man. This is the first demonstration of YAC complementation as a valuable adjunct strategy for positional cloning of a human gene.     

Alternative configuration for an optical ring resonator angular rate sensor by using a standard laser diode

In this work, we present an alternative approach to angular velocity optical sensing based on two-ring resonators. This configuration admits the use of a standard laser diode source (0.1 nm, 10,000 MHz, FWHM) reaching higher sensitivities when narrow spectral laser sources (1 MHz, FWHM) are used. We compare this configuration with the standard single-ring resonator angular rate sensor (SRARS), which must use a narrow laser at input. Finally, we conclude that the sensitivity of this new approach can also be enhanced by coupling high-power broadband laser sources in a large range (from 1°/h to 10,000°/h), reaching performance similar to that of a standard SRARS configuration.     

Solution properties of poly(thiocarbonates)

Poly(thiocarbonates) with alkyl side chains have been prepared, and the solution properties of these polymers were studied in different solvents. Comparison with other poly(thiocarbonate) analogues and poly(carbonates) shows that the conformational parameter (K_θ) and rigidity factor increase as the volume of the side chain increases. The effect of the side-chain structure on the solution properties is analyzed.     

Halogenated polymers with high thermal stability and flame-resistance

A series of polyamides and poly(amido-imides) with variable chlorine content in the nitrogen monomer as in the carboxylic monomer have been prepared. All the polymers showed excellent thermal properties and fairly good flame-resistance characteristics.