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Spectrophotometric Determination of Zinc Using 7-(4-Nitrophenylazo)-8-Hydroxyquinoline-5-Sulfonic Acid
Korn, Maria das Gra?as Andrade;Ferreira, Adriana Costa;Teixeira, Leonardo Sena Gomes;Costa, Antonio Celso Spínola;
Journal of the Brazilian Chemical Society , 1999, DOI: 10.1590/S0103-50531999000100008
Abstract: a sensitive and selective spectrophotometric method is proposed for the rapid determination of zinc(ii) using an 8-hydroxyquinoline derivative, 7-(4-nitrophenylazo)-8-hydroxyquinoline-5-sulfonic acid (p-niazoxs), as a new spectrophotometric reagent. the reaction between the p-niazoxs and zinc(ii) is instantaneous at ph 9.2 (borax buffer) and the absorbance remains stable for over 24 h. the method allows the determination of zinc over the range of 0.05-1.0 mg ml-1 with a molar absorptivity of 3.75x104 l mol-1 cm-1 and features a detection limit of 15 ng ml-1. the proposed method has been successfully applied to the determination of zinc in several pharmaceutical preparations and copper alloys. the precision (r.s.d. < 2%) and the accuracy obtained were satisfactory.
Spectrophotometric Determination of Zinc Using 7-(4-Nitrophenylazo)-8-Hydroxyquinoline-5-Sulfonic Acid  [cached]
Korn Maria das Gra?as Andrade,Ferreira Adriana Costa,Teixeira Leonardo Sena Gomes,Costa Antonio Celso Spínola
Journal of the Brazilian Chemical Society , 1999,
Abstract: A sensitive and selective spectrophotometric method is proposed for the rapid determination of zinc(II) using an 8-hydroxyquinoline derivative, 7-(4-nitrophenylazo)-8-hydroxyquinoline-5-sulfonic acid (p-NIAZOXS), as a new spectrophotometric reagent. The reaction between the p-NIAZOXS and zinc(II) is instantaneous at pH 9.2 (borax buffer) and the absorbance remains stable for over 24 h. The method allows the determination of zinc over the range of 0.05-1.0 mug mL-1 with a molar absorptivity of 3.75x10(4) L mol-1 cm-1 and features a detection limit of 15 ng mL-1. The proposed method has been successfully applied to the determination of zinc in several pharmaceutical preparations and copper alloys. The precision (R.S.D. < 2%) and the accuracy obtained were satisfactory.
Investigation on stability of directionally solidified CBr4--C2Cl6 lamellar eutectic by using multiphase field simulation
Investigation on stability of directionally solidified CBr4-C2Cl6 lamellar eutectic by using multiphase field simulation

Zhu Yao-Chan,Wang Jin-Cheng,Yang Gen-Cang,Zhao Da-Wen,
朱耀产
,王锦程,杨根仓,赵达文

中国物理 B , 2007,
Abstract: With the multiphase field method, the stability of lamellar basic state is investigated during the directional solidification of eutectic alloy CBr4--C2Cl6. A great number of lamellar patterns observed in experiments are simulated, and a stability diagram for lamellar pattern selections is presented. The simulated growth behaviours of these patterns are found to be qualitatively consistent with Karma \textit{et al}'s numerical calculations and experimental results. The formation of the primary instability is attributed to the destabilization of solute boundary layer.
Lamellar ceramics of Ca2SiO4 prepared by mechanical activation of powders
Cabrera, A.B.;Mendoza, M.E.;
Revista mexicana de física , 2006,
Abstract: stoichiometric mixtures of calcium carbonate and silicon oxide have been mechanically activated by milling during several hours (29 and 50) previous to the solid state reaction, in order to obtain dicalcium silicate, ca2sio4. x-ray powder diffraction and differential thermal analysis studies show that the mechanical processing of the powders induces changes in the orientational uniformity of crystallites and the diminution of the decomposition temperature of the calcium carbonate. microlamellar particles of β-ca2sio4 were obtained when the solid state reaction was achieved at 1450°c, whereas β-ca2sio4 and α'l-ca2sio4 phases were obtained when the reaction took place at 1000°c. by means of the powder processing described in this work, we can prepare phase β-ca2sio4 without any chemical stabilizer and with an unusual lamellar morphology.
Molecular Interactions in Binary Mixture of Polymethylmethacrylate with Acetic Acid  [cached]
Richa Saxena,S.C. Bhatt
International Journal of Chemistry , 2010, DOI: 10.5539/ijc.v2n2p164
Abstract: Solution is prepared by mixing Polymethylmethacrylate in solid form with acetic acid, which at different concentration were used to measure density, viscosity & ultrasonic velocity in the temperature range 300C-650C, using ultrasonic interferometer at 1MHz. Using these measured values of density, viscosity & sound velocity, different parameters like, adiabatic compressibility, acoustic impedance and relaxation time have been measured for solution of polymethylmethacrylate with acetic acid under different conditions of temperature and concentration. Variations of above parameters with respect to temperature and concentration have been discussed in terms of molecular interactions.
Photonic engineering of hybrid metal-organic chromophores  [PDF]
Micka?l P. Busson,Brice Rolly,Brian Stout,Nicolas Bonod,Jér?me Wenger,Sébastien Bidault
Physics , 2012, DOI: 10.1002/anie.201205995
Abstract: We experimentally demonstrate control of the absorption and emission properties of individual emitters by photonic antennas in suspension. The method results in a new class of water-soluble chromophores with unprecedented photophysical properties, such as short lifetime, low quantum yield but high brightness.
Photoresponsive Block Copolymers Containing Azobenzenes and Other Chromophores  [PDF]
Haifeng Yu,Takaomi Kobayashi
Molecules , 2010, DOI: 10.3390/molecules15010570
Abstract: Photoresponsive block copolymers (PRBCs) containing azobenzenes and other chromophores can be easily prepared by controlled polymerization. Their photoresponsive behaviors are generally based on photoisomerization, photocrosslinking, photoalignment and photoinduced cooperative motions. When the photoactive block forms mesogenic phases upon microphase separation of PRBCs, supramolecular cooperative motion in liquid-crystalline PRBCs enables them to self-organize into hierarchical structures with photoresponsive features. This offers novel opportunities to photocontrol microphase-separated nanostructures of well-defined PRBCs and extends their diverse applications in holograms, nanotemplates, photodeformed devices and microporous films.
Reactions of lignin chromophores of the enal and enone types with sulfite  [cached]
Lundquist, Knut,Jim Park?s,Magnus Paulsson,Cyril Heitner
BioResources , 2007,
Abstract: In NaHSO3-solutions of coniferaldehyde and its methyl ether (models for lignin chromophores of the cinnamaldehyde type) a dynamic equilibrium between the aldehydes and their hydrogen sulfite adducts is set up. A comparatively slow addition of hydrogen sulfite to the double bond leading to 1,3-disulfonic acid derivatives occurs; coniferaldehyde reacts slower than its methyl ether. In Na2SO3-solution both aldehydes are rapidly converted to 1,3-disulfonic acid derivatives. The results suggest that in both NaHSO3-solution and Na2SO3-solution the free cinnamaldehydes and sulfite ion are the reactants in the formation of disulfonic acid derivatives. Alkaline treatment of the 1,3-disulfonic acids leads to regeneration of the cinnamaldehydes. On prolonged storage in Na2SO3-solution, the 1,3-disulfonic acid derivative of the methyl ether of coniferaldehyde undergoes reactions leading to colored products and regeneration of the cinnamaldehyde on alkaline treatment fails. A model compound representative of lignin chromophores of enone type (trans-3,3’,4,4’-tetramethoxychalcone) rapidly undergoes addition to the double bond with formation of a sulfonic acid derivative in Na2SO3-solution. Treatment of a second model of enone type, 2,6-dimethoxy-p-quinone, with NaHSO3/Na2SO3-solution results in formation of a sulfonic acid derivative. The reactions of lignin chromophores of the enone and enal types with hydrogen sulfite/sulfite are discussed.
Conjugated donor-acceptor chromophores in solution: non-linearity at work  [PDF]
Francesca Terenziani,Anna Painelli
Physics , 2001,
Abstract: We propose a model that, accounting for the intrinsic non-linearity of the electronic system, is able to rationalize steady-state electronic and vibrational spectra of polar chromophores in solution, as well as time-resolved experiments.
Evaluation of polymethylmethacrylate as ocular implant in rabbits subjected to evisceration
Oriá, Arianne Pontes;Dórea Neto, Francisco de Assis;Santos, Luís Alberto dos;Piza, Evandro de Toledo;Brunelli, Adriana Torrecilhas Jorge;Nishimori, Celina Tie;Souza, Ana Letícia Groszewicz de;Gomes Junior, Deusdete Concei??o;Laus, José Luiz;
Revista Ceres , 2012, DOI: 10.1590/S0034-737X2012000400004
Abstract: spheres of different types of material are used for the replacement of lost volume after removal of the eye bulb or its content to prevent contraction of the orbital cavity. the aim of this study was to evaluate the scope of polymethylmethacrylate (pmma) used as intraocular implant in eviscerated rabbit eye. twelve new zealand rabbits underwent unilateral evisceration of the left eye, with subsequent implantation of pmma sphere 12 mm in diameter. clinical evaluation was performed daily during the first 15 days after surgery and every 15 days until the end of the study period (180 days). for the histopathological analysis, three animals per trial underwent enucleation at 15, 45, 90 and 180 days after evisceration. there was no wound dehiscence, signs of infection or implant extrusion in any animal throughout the study period. histological examination revealed the formation of fibrovascular tissue around the implants. the pmma behaved as inert and non-integrable.
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