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Maximum Absorption (maximum + absorption)
Terms modified by Maximum Absorption Selected AbstractsAn in vitro evaluation of various Rosa damascena flower extracts as a natural antisolar agentINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 6 2003H. Tabrizi Synopsis The aim of this work was to evaluate ultraviolet (UV) absorption ability of various extracts of Rosa damascena flowers as an antisolar agent. Extracts were prepared using the following solvent mixtures: water:ethanol (50 : 50), ethyl acetate:ethanol (80 : 20) and ether. The hydroalcoholic and ethyl acetate:ethanol extracts were prepared by maceration, and ether extract was prepared by soxhletion. Preliminary studies on the extracts prepared confirmed the presence of flavonoids as the major components of all extracts. Next, the UV absorption spectra (in the range of 200,400 nm) of all extracts were obtained. Results show that all three extracts can effectively absorb UV radiation in the range of 200,400 nm. However, the range giving maximum absorption for the hydroalcoholic, ethyl acetate:ethanol and ether extracts were 200,320, 250,360 and 230,370 nm, respectively. In the next stage, extracts prepared were incorporated into an oil in water cream base (prepared based on preliminary studies), at two concentrations of 5 and 8%. The sun protection factor (SPF) of these creams were determined. Based on the findings, the hydroalcoholic extract seems to give the highest SPF among the three extracts evaluated, when incorporated to the cream base. On the other hand, by performing a few physicochemical tests on the prepared creams, cream containing 5% ether extract showed the most desirable appearance and stability among the creams investigated. The UV absorption ability of these extracts is suggested to be because of the presence of flavonoid compounds within the extracts. However, it should be noted that in order to obtain an effective suncare product with high SPF values, these extracts could be used along with other synthetic antisolar agents. Résumé Le but de ce travail était d'évaluer la capacité d'absorption des Ultraviolets (UV) de différents extraits de fleurs de Rosa damascena en tant qu'agents de protection solaire. Les extraits ont été préparés par utilization des mélanges de solvants suivants: Eau:ethanol (50 : 50), Acetate d'éthyle:ethanol (80 : 20) et l'Ether. Les extraits hydro-alcoolique et d'acétate d'ethyle:ethanol ont été réalisés par macération tandis que l'extrait d'éther était obtenu par l'utilization d'un soxhlet. Les études préliminaires des extraits ainsi préparés confirmaient la présence de flavonoïdes en tant que constituants majeurs de tous les extraits. Les spectres d'absorption UV (échelle 200,400 nm) furent ensuite obtenus. Les résultats montrent que tous les extarits peuvent absorber fortement les radiations UV dans l'échelle de 200 à 400 nm. Cependant, les domaines donnant le maximum d'absorption pour les extraits hydroalcoolique, acétate d'éthyle:ethanol et ether étaient respectivement de 200,320, 250,360 et 230,370 nm. Dans une étape ultérieure, les extraits ont été incorporés dans une base type crème huile dans l'eau (préparée selon des études préliminaires) aux deux concentrations de 5 et 8%. Les facteurs de protection solaire (SPF) de ces crèmes étaient ensuite déterminés. Les résultats ont montré que l'extrait hydroalcoolique semblait, parmi les trois, conduire au plus fort SPF, quand incorporé dans une base type crème. De plus, en conduisant quelques tests physioco chimiques sur les crèmes préparées, la crème contenant 5% de l'extrait par éther, comparé aux autres crèmes, offrait l'aspect le plus désirable et le plus stable. Il est suggéré que la capacité d'absorption UV de ces extraits est due à la présence des composés de type flavonoïdes en leur sein. On doit noter, cependant, qu'afin d'obtenir un produit solaire efficace à haut SPF, ces extraits pourraient être adjoints à d'autres filtres solaires synthétiques. [source] Comparative bioavailability study in dogs of a self-emulsifying formulation of progesterone presented in a pellet and liquid form compared with an aqueous suspension of progesteroneJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 6 2004Catherine Tuleu Abstract A pellet formulation of progesterone in a self-emulsifying system (SES) was prepared by the process of extrusion/spheronization to provide a good in vitro drug release (100% within 30 min, T50% at 13 min). A three-way randomized crossover study was performed in six fasted male beagle dogs with these pellets and the same SES liquid formulation, both contained in a hard shell capsule, and an aqueous suspension. The same dose of progesterone (16 mg) in pellets and in the SES liquid formulation resulted in similar AUC, Cmax and Tmax values, estimated from progesterone plasma levels by 125I radioimmunoassay. Although the maximum absorption was slightly retarded (0.5 to 1 h) by SES (pellets and liquid), AUC and Cmax were approximately seven and nine times greater then those obtained when an aqueous suspension formulation of the same dose of progesterone was administered to the same dogs. These results showed that it was possible to improve the bioavailability of the poorly soluble, poorly permeable progesterone when administered in SES. Moreover, presenting the progesterone in the form of a pellet did not prevent the release of the drug in vivo. These data demonstrate the utility of extrusion/spheronization in delivering a nonaqueous system in a novel solid dosage form. © 2004 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 93:1495,1502, 2004 [source] Theoretical design study on multifunctional triphenyl amino-based derivatives for OLEDsJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 11 2009Lu-Yi Zou Abstract The use of triphenyl amino-based derivatives in organic light-emitting diodes (OLEDs) can significantly improve their efficiency and stability and especially their electroluminescence characteristics , most of the new hole-transport materials have this feature. In this study, a series of triphenyl amino-based compounds were computed, including two newly designed molecules. They can function as charge transport materials and emitters with high efficiency and stability. To reveal the relationship between the properties and structures of these bifunctional and multifunctional electroluminescent materials, the ground and excited state geometries were optimized at the B3LYP/6-31G(d), HF/6-31G(d), TD-B3LYP/6-31G(d), and CIS/6-31G(d) levels, respectively. The ionization potentials (IPs) and electron affinities (EAs) were computed. The lowest excitation energies, the maximum absorption, and emission wavelengths of these compounds were calculated by employing the time-dependent density functional theory (TD-DFT) method. Also, the mobilities of holes and electrons were studied computationally based on the Marcus electron transfer theory. The CH2Cl2 solvent effect on the absorption spectra of N,N,-di-1-naphthyl- N,N,-diphenylbenzidine (NPB) was considered by polarizable continuum model (PCM). The results obtained for these compounds are in good agreement with the experimental values. These data show that the proposed compounds 1 and 2 (N,B-di-1-naphthyl-N,B-diphenylbenzidine and Mes2N[p-4,4,-biphenyl-NPh(1-naphthyl)]), are multifunctional and bifunctional materials similar to Mes2B[p -4,4,-biphenyl-NPh(1-naphthyl)] (BNPB) and NPB, respectively. Copyright © 2009 John Wiley & Sons, Ltd. [source] 3H -1,2-Dithiole-3-thione derivatives as novel solvatochromic dyesJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 11 2008Alejandro M. Fracaroli Abstract The UV,Vis spectrum of 5-(1-butylthio)-3H -1,2-dithiole-3-thione (1a) and that of the chromium pentacarbonyl complex of 5-methyl-3H -1,2-dithiole-3-thione (3) present significant changes with the solvent polarity. The two absorption bands shown by the compounds in the region above 300,nm were identified by theoretical calculations. For Compound 1a these are n,,* and ,,* transitions and for Compound 3 the longest wavelength absorption corresponds to a charge transfer band and shows a remarkably negative solvatochromism. Not only has the wavelength of maximum absorption changed with the solvent but also the ratio of the absorbances at the two wavelengths. The effect of solvents was correlated with solvatochromic parameters such as ,* and ,. The spectrum of 5-(1-butylthio)-3H -1,2-dithiole-3-one (2) was also measured in different solvents but in this case the changes observed are less significant than for the other two compounds. The spectra of 1a and 3 were also determined in the presence of anionic (SDS), cationic (CTAB), and neutral surfactants (Brig-35) and it is shown that these compounds can be used as probes for the polarity of the binding sites of organized assemblies. Copyright © 2008 John Wiley & Sons, Ltd. [source] Optical properties of a novel fluorene-based thermally stable conjugated polymer containing pyridine and unsymmetric carbazole groupsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 4 2009Der-Jang Liaw Abstract A new diiodo monomer containing heterocyclic pyridine and carbazole groups was synthesized via Chichibabin reaction and used in the preparation of a conjugated polymer via Suzuki coupling approach. The conjugated polymer was highly soluble in common organic solvents such as NMP, THF, dichloromethane, chloroform, toluene, xylene, and benzene at room temperature. The polymer had high glass transition temperature at 191 °C and Td10 at 434 °C in nitrogen atmosphere. The pristine polymer exhibited the UV,vis maximum absorption at 355 nm and shifted to 420 nm after protonation. The emission of the polymer in THF solution changed from the blue region with maximum peak at 400 nm to the yellow region with maximum peak at 540 nm after protonated by HCl, and the intensity of emission depended on the concentration of acid. The polymer also showed electrochromic behavior under applied voltage. The emission color of the polymer film changed from blue (435 nm) to yellow (570 nm) when 2.5 V bias voltage was applied. The polymer also exhibited write-once and read-many-times (WORM) polymer memory effect with tristable states. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 991,1002, 2009 [source] A versatile preparation of azobenzene-dye functionalized colored polymer nanoparticles by surface modificationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 10 2008Caroline Cannizzo Abstract A series of stable and translucent colored nanolatex, that is, colloidal aqueous suspensions of dye-tagged polymer nanoparticles (NPs) in the 15- to 20-nm diameter range, have been prepared by covalent attachment of azobenzene chromophores to the surface of reactive NPs. Primary crosslinked NPs bearing chlorobenzyl groups were produced by microemulsion copolymerization of styrene and vinylbenzylchloride. Amine-functionalized NPs were obtained after a second functionalization step with polyamines (cyclam and polypropyleneimine dendrimers of first and third generations). Dye-doped particles were obtained by reacting pyridylazo-dimethylaminobenzene (PADA) with chlorobenzyl-NPs and by reacting amine-reactive dimethylaminoazobenzene dyes (DABsyl, DAB-ITC) as well as Disperse Red 1 acrylate with polyamine-coated NPs. Regardless the dye solubility, the grafting readily proceeded in aqueous suspensions at room temperature in the presence of a cationic surfactant without added solvent. Purple, red, and orange suspensions (maximum absorption around 550, 500, 430 nm), with dye loads ranging from 0.3 to 1.2 mmol/g, corresponding to 400,1800 azobenzene residues per NP, are obtained. The reported results indicate that functional polymer NPs, with remarkably accessible multiple anchoring sites, are useful building blocks. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3375,3386, 2008 [source] Synthesis of hyperbranched polymers with precise conjugation lengthJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 6 2007Jing Li Abstract A set of AB2 type monodisperse conjugated oligomers carrying two bromo functional groups and one boronic ester functional group were prepared by iterative deprotection and Sonogashira cross-coupling reactions. Suzuki polycondensation of these AB2 type monodisperse oligomers afforded hyperbranched polymers. The hyperbranched conjugated polymers we prepared possess not only precisely controlled conjugation length like monodisperse conjugated oligomers but also the structural feature of hyperbranched polymers. Optical property investigation demonstrated that the maximum absorption and emission wavelength red-shifted along with the increasing of the conjugation length between the two branching points and the hyperbranched structure could effectively reduce the aggregation of the conjugated polymer chains. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1084,1092, 2007 [source] Polymeric Photoinitiator Containing In-Chain Thioxanthone and Coinitiator AminesMACROMOLECULAR RAPID COMMUNICATIONS, Issue 6 2004Xuesong Jiang Abstract Summary: A polymeric photoinitiator (PTXP) containing in-chain thioxanthone (TX) and coinitiator amines was synthesized by step-growth polymerization, as well as low-molecular-weight model compounds. Photopolymerizations of methyl methacrylate (MMA) initiated by these photoinitiator systems were studied. Compared with corresponding low-molecular-weight model compounds, PTXP has a similar UV-vis spectrum with a red-shifted maximum absorption, and weaker fluorescence emission, and can photoinitiate the polymerization of MMA more effectively. The structure of PTXP, the photoinitiator synthesized here. [source] Primary Photophysical Properties of Moxifloxacin, A Fluoroquinolone AntibioticPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 5 2008Fernando Lorenzo The photophysical properties of the fluoroquinolone antibiotic moxifloxacin (MOX) were investigated in aqueous media. MOX in water, at pH 7.4, shows two intense absorption bands at 287 and 338 nm (, = 44 000 and 17 000 dm3 mol,1 cm,1, respectively). The absorption and emission properties of MOX are pH-dependent, pKa values for the protonation equilibria of both the ground (6.1 and 9.6) and excited singlet states (6.8 and 9.1) of MOX were determined spectroscopically. MOX fluoresces weakly, the quantum yield for fluorescence emission being maximum (0.07) at pH 8. Phosphorescence from the excited triplet state in frozen ethanol solution has a quantum yield of 0.046. Laser flash photolysis and pulse radiolysis studies have been carried out to characterize the transient species of MOX in aqueous solution. On laser excitation, MOX undergoes monophotonic photoionization with a quantum yield of 0.14. This leads to the formation of a long-lived cation radical whose absorption is maximum at 470 nm (,470 = 3400 dm3 mol,1 cm,1). The photoionization process releases hydrated electron which rapidly reacts (k = 2.8 × 1010 dm3 mol,1 s,1) with ground state MOX, yielding a long-lived anion radical with maximum absorption at 390 nm (,390 = 2400 dm3 mol,1 cm,1). The cation radical of MOX is able to oxidize protein components tryptophan and tyrosine. The bimolecular rate constants for these reactions are 2.3 × 108 dm3 mol,1 s,1 and 1.3 × 108 dm3 mol,1 s,1, respectively. Singlet oxygen sensitized by the MOX triplet state was also detected only in oxygen-saturated D2O solutions, with a quantum yield of 0.075. [source] pH sensor based on polyaniline and aniline,anthranilic acid copolymer films using quartz crystal microbalance and electronic absorption spectroscopyPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 8 2008M. M. Ayad Abstract The pH sensitivity based on conducting polyaniline (PANI) and copolymer of aniline and o -anthranilic acid (AA) films were studied using quartz crystal microbalance (QCM) technique and UV,Vis spectroscopy. The sensor was constructed from these polymer films coated on the electrode of the QCM. The resonant frequency changes as a function of pH in the range of 2,12 were measured. These changes are quantitative indication of the degree of dedoping or redoping of the polymer films upon the subsequent exposure of the electrode to 0.25,M sulfuric acid and different pH solutions. There are two linear regressions between the frequency change and pH with two different and opposite slopes in the regions from 2 to 9 and 9 to 12. The pH sensitivity of the copolymer film was found to be less than using the PANI film. Thin films of PANI and copolymer, which were chemically polymerized in a sulfuric acid solution, were deposited onto the inner walls of the quartz cuvettes. The UV,Vis absorption spectra of these films were measured in different pH solutions. Relations between the maximum absorption and its wavelength versus pH were constructed. The copolymer film shows some advantages over the PANI film. The difference between the PANI and copolymer films as pH sensors using the QCM and electronic absorption extends from the determination of pKa for both films. Copyright © 2008 John Wiley & Sons, Ltd. [source] Two-photon Dissociation Study of Carbon Disulfide in Acetonitrile at 266 nmCHINESE JOURNAL OF CHEMISTRY, Issue 1 2006Hao-Jie Fang Abstract Using laser flash photolysis/transient absorption technique for the study of two photon photodissociation of carbon disulfide in acetonitrile solution at 266 nm, the transient UV-Vis absorption spectrum of Rydberg state CS2 (6s,g) within 240,370 nm and subsequent dissociation product CS (,3,) with the maximum absorption at 260 nm were directly observed. The lifetime of CS (,3,) in the nitrogen and oxygen saturated solution is also studied in our experiment. [source] | |||||||||||||