Polyfluorene based blends for white light emission

Single layer white light emitting diodes were constructed with blends containing as blue emitter and matrix host poly(9,9-dihexyl-2,7-fluorene) (LaPPS10), and the green and red emitters poly[(9,9-dihexyl-9H-fluorene-2,7-diyl)-1,2-ethenediyl-1,4-phenylene-1,2-ethenediyl] (LaPPS16) and poly[2-methoxy-5-(2-ethylhexoxy)-1,4-phenylene vinylene] (MEH-PPV), respectively, as guests components. Two blends were studied: LaPPS10:LaPPS16:MEH-PPV = 100:0.01:0.20 (w/w) (JF14) and another with the same components and a second blue emitter: a copolymer of poly(methyl methacrylate-co-methyl antracenyl methacrylate), P(MMA-co-MMAnt), with the composition LaPPS10:P(MMA-co-MMAnt):LaPPS16:MEH-PPV = 100:40:0.01:0.20 (w/w) (JF17). The PL spectra of JF14 and JF17 in the higher energy edge are characteristic of the matrix (LaPPS 10). The morphological characterization showed the formation of a biphasic structure with a matrix of LaPPS10 and segregated domains of MEH-PPV in the case of JF14 and of P(MMA-co-MMAnt) in the case of JF17. Significant differences between EL and PL spectra were observed for the blends indicating that the mechanism for the excited states or quenching processes are very different in both cases. In addition, the EL emissions suggested that the cascade mechanism for the charge migration or charge recombination or energy transfer processes are also incomplete allowing more than one type of emission. EL spectra were red-shifted in relation to PL, which was partly attributed to the trapping of energy carriers that may occur in EL, apart from energy transfer. The CIE coordinates for EL emission of JF14 blend the coordinates are (0.30, 0.32) and for JF17 blend are (0.29, 0.38) corresponding to white light emission. Spectroscopic data brought evidence of the formation of the β phase in the polyfluorene matrix, and due to differences in band gap, it was concluded that hole carriers tend to be injected into that phase rather than into the disordered one, leading to the proposal that EL emission was predominantly originated from the β phase.CNPqFAPESPINCT-INE

Self-aggregated nanoparticles of N-dodecyl,N′-glycidyl(chitosan) as pH-responsive drug delivery systems for quercetin

In this study, pH-responsive amphiphilic chitosan (CS) nanoparticles were used to encapsulate quercetin (QCT) for sustained release in cancer therapy. The novel CS derivatives were obtained by synthesis with 2,3-epoxy-1-propanol, also known as glycidol, followed by acylation with dodecyl aldehyde. Characterization was performed by spectroscopic, viscosimetric, and size-determination methods. Critical aggregation concentration, morphology, entrapment efficiency, drug release profile, cytotoxicity, and hemocompatibility studies were also carried out. The average size distribution of the self-assembling nanoparticles measured by dynamic light scattering ranged from 140 to 300 nm. In vitro QCT release and Korsmeyer–Peppas model indicated that pH had a major role in drug release. Cytotoxicity assessments indicated that the nanoparticles were non-cytotoxic. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay further revealed that QCT-loaded nanoparticles could inhibit MCF-7 cell growth. In vitro erythrocyte-induced hemolysis indicated the good hemocompatibility of the nanoparticles. These results suggest that the synthesized copolymers might be potential carriers for hydrophobic drugs in cancer therapy

A profundidade óptica em 45 e 90 GHz no observatório do El Leoncito

A profundidade óptica é um parâmetro importante de ajuste na obtenção correta do fluxo de energia que caracteriza uma explosão solar. Portanto, conhecer seu valor e as variáveis que influenciam em sua modificação através do ano, em determinada localidade é fundamental. Assim, foi feito uma análise estatística dos valores da opacidade nos anos de 2012 e 2013 para as frequências de operação dos radiotelescópios POEMAS. Sendo que os valores da opacidade foram obtidos através do método “tipping” para 45 GHZ e 90 GHz. Como resultado foi obtido do valor médio da profundidade óptica para o ano de 2012 para as frequências de 45 GHz e 90 GHZ (0,069 ± 0,005 Np e 0,057 ± 0,014 Np respectivamente) e para 2013 os valores de 0,068 ± 0,005 Np para 45 GHz e 0,057 ± 0,017 para 90 GHz. Também se fez um estudo para essas mesmas frequências, dos valores de opacidade para diversas estações do ano, para os anos de 2012 e 2013, observando-se um padrão diferenciado de opacidade para a estação úmida (verão/início do outono), do resto do ano (estação seca) para ambas frequências de estudo. Das análises foi notado que as medidas de opacidade de 90 GHz eram mais instáveis que as de 45 GHz, e que, os valores da opacidade não eram crescentes com a frequência, contrariando o esperado na literatura. Obtivemos também, para os dois anos, uma relação das frequências entre si no período seco, e se observou que as opacidades eram intercambiáveis, o que resulta importante para a frequência de 90 GHz que produz menos dados pelo método “tipping” e é mais ruidosa. Portanto, obtivemos para o ano de 2012 a relação 90= (3,499±0,063).45-(0,181±4,5x10-3) e para 2013 obtivemos 90= (3,173±0,0070).45+(0,158±4,5x10-3), por fim. Para o biênio 2012/2013 o resultado obtido foi de 90 =(3,384±0,041).45-(0,173±2,9x10-3).Também foram realizados estudos estatísticos para o PWV nos períodos analisados (2012/2013) e os valores do PWV (obtidos através da rede AERONET situada em EL Leoncito) relacionados com a opacidade gerando expressões para as duas frequências do POEMAS: 90=(8,3x10-3±2,3x10-5).PWV+(3,3x10-2±2,7x10-4) e 45=(2,2x10-3±2,3x10- 5).PWV+(6,2x10-2±8,5x10-5). Por fim, foram realizadas algumas simulações com o software ATM - Atmospheric Transmission at Microwaves que mostraram concordância entre os valores do modelo e a opacidade obtida experimentalmente.The optical depth is an important parameter of adjustment in obtaining the correct energy flow that characterizes a solar explosion. Therefore, knowing its value and the variables that influence its modification through the year, in each locality is fundamental. Thus, A statistical analysis of the opacity values was made in the years 2012 and 2013 for the operating frequencies of the radio telescopes poems. The opacity values were obtained through the "tipping" method for 45 GHz and 90 GHz. As a result it was obtained from the average value of the optical depth for the year 2012 for the frequencies of 45 GHz and 90 GHz (0.069 ± 0.005 np and 0.057 ± 0.014 NP respectively) and for 2013 the values of 0.068 ± 0.005 NP for 45 GHz and 0.057 ± 0.017 for 90 GHz. Also if f EZ A study for these same frequencies, of the opacity values for several seasons of the year, for the years 2012 and 2013, observing a differentiated pattern of opacity for the wet season (Summer/early autumn), the rest of the year (dry season) for both Study frequencies. From the analyses it was noted that the opacity measurements of 90 GHz were more unstable than those of 45 GHz, and that the opacity values were not increasing with the frequency, contradicting what was expected in the literature. For the two years, we also obtained a relationship between the frequencies of each other in the dry season, and it was observed that the opacities were interchangeable, which is important for the frequency of 90 GHz that produces less data by the "tipping" method and is noisiest. Therefore, the ratio 90= (3,499±0.063).45-(0,181±4,5x10-3) and for 2013 we obtained 90= (3,173± 0.0,070).45+(0.158±4, 5x10-3), at last. For the biennium 2012/2013 the obtained result was 90 = (3,384 ± 0,041).45-(0,173 ± 2, 9x10-3). Statistical studies were also performed for PWV in the analyzed periods (2012/2013) and PWV values (obtained through The AERONET network located in EL Leoncito) related to the opacity generating expressions for the two frequencies of POEMAS: 90 =(8,3x10- 3±2,3x10-5).PWV + (3,3x10-2±2,7x10-4) and 45= (2, 2x10-3±2,3x10-5).PWV+(6, 2x10- 2±8,5x10-5). Finally, some simulations were performed with the ATM - Atmospheric Transmission at microwaves software that showed concordance between the model values and the opacity obtained Experimentally.Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorFundo Mackenzie de Pesquis

Role of surfactants in the sorption of the whitening agent Tinopal CBS onto viscose fibers: A fluorescence spectroscopy study

In the present work, we studied the role of an anionic surfactant, sodium dodecyl sulfate, and a cationic surfactant, dodecyltrimethylammonium chloride, in the sorption of 4,4'-distyrylbiphenyl sodium sulfonate (Tinopal CBS) onto modified cellulose fibers. Fluorescence spectroscopy was used to quantify the amount of sorbed Tinopal CBS on the fiber surface. Differences in the spectral properties and the efficiency of sorption of the whitener/surfactant/fiber system are explained in terms of electrostatic interactions. Our results also show that the sorption efficiency is greater for solutions containing cationic surfactants only below the critical micelle concentration, while anionic surfactants show a smooth influence on the sorption process.22249866987

Whitening regenerated cellulose fibers using fluorescent agent, surfactants, and saltucolor indices measurements

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)The whitening efficiency of regenerated cellulose fibers using sodium 4,4'-distyrylbiphenyl sulfonate in the presence of an anionic surfactant (sodium dodecylsulfate) and a cationic surfactant (dodecyl trimethyl ammonium chloride) and salt (NaCl) was determined by fluorescence spectroscopy and color index values (brightness, whiteness, and yellowness). Epifluorescence images gave an intense blue color with an apparent uniform emission distribution. In absence of salt, the whitening efficiency was higher for aqueous solutions containing cationic surfactant below critical micellar concentration (cmc). In presence of salt, whitening efficiency was higher for anionic surfactant and more important. The concentration of surfactant required for greater brightness, whiteness, and yellowness was lower than that required in absence of salt. These data were discussed by the decrease of the cmc and by the screening of the modified cellulose fibers by counter ions coming from the salt. The role of surfactants was explained by the admicelization during the sorption process. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012124543714380Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Whitening Regenerated Cellulose Fibers Using Fluorescent Agent, Surfactants, And Salt-color Indices Measurements

The whitening efficiency of regenerated cellulose fibers using sodium 4,4′-distyrylbiphenyl sulfonate in the presence of an anionic surfactant (sodium dodecylsulfate) and a cationic surfactant (dodecyl trimethyl ammonium chloride) and salt (NaCl) was determined by fluorescence spectroscopy and color index values (brightness, whiteness, and yellowness). Epifluorescence images gave an intense blue color with an apparent uniform emission distribution. In absence of salt, the whitening efficiency was higher for aqueous solutions containing cationic surfactant below critical micellar concentration (cmc). In presence of salt, whitening efficiency was higher for anionic surfactant and more important. The concentration of surfactant required for greater brightness, whiteness, and yellowness was lower than that required in absence of salt. These data were discussed by the decrease of the cmc and by the screening of the modified cellulose fibers by counter ions coming from the salt. The role of surfactants was explained by the admicelization during the sorption process. © 2011 Wiley Periodicals, Inc.124543714380Blackburn, R.S., Harvey, A., Kettle, L.L., Manian, A.P., Payne, J.D., Russell, S.J., (2007) J Phys Chem B, 111, p. 8775Mischnick, P., Heinrich, J., Gohdes, M., Wilke, O., Rogmann, N., (1985) Macromol Chem Phys, 2000, p. 201Jakob, H.F., Fengel, D., Tschegg, S.E., Fratzl, P., (1995) Macromolecules, 28, p. 8782Ha, M.A., Apperley, D.C., Evans, B.W., Huxham, M., Jardine, W.G., Vietor, R.J., Reis, D., Jarvis, M.C., (1998) Plant J, 16, p. 183Muller, M., Hori, R., Itoh, T., Sugiyama, J., (2002) Biomacromolecules, 3, p. 182Abu-Rous, M., Ingolic, E., Schuster, K.C., (2006) Cellulose, 13, p. 411Kreze, T., Strnad, S., Stana-Kleinschek, K., Ribitsch, V., (2001) Mater Res Innov, 4, p. 107Krassig, H., (1978) Tappi, 61, p. 93Kotek, R., (2007) Handbook of Fiber Chemistry, p. 667. , In, 3rd ed. Lewin, M. Ed.CRC Press: New YorkStana-Kleinschek, K., Strnad, S., Ribitsch, V., (1999) Polym Eng Sci, 39, p. 1412Stana, K.K., Pohar, C., Ribitsch, V., (1995) Colloid Polym Sci, 273, p. 1174Timofei, S., Schmidt, W., Kurunczi, L., Simon, Z., (2000) Dyes Pigments, 47, p. 5Sarrazin, P., Beneventi, D., Chaussy, D., Vurth, L., Stephan, O., (2009) Colloids Surf A: Physicochem Eng Aspects, 334, p. 80Iamazaki, E.T., Atvars, T.D.Z., (2007) Langmuir, 23, p. 12886Leaver, I.H., Milligan, B., (1984) Dyes Pigments, 5, p. 109Canonica, S., Kramer, J.B., Reiss, D., Gygax, H., (1997) Environm Sci Tech, 31, p. 1754Choudhury, A.K.R., (2006) Textile Preparation and Dyeing, , Science Publishers: New YorkIamazaki, E.T., Atvars, T.D.Z., (2006) Langmuir, 22, p. 9866Lewis, D.M., (1998) J Soc Dyers Col, 114, p. 264Vigil, M.R., Bravo, J., Baselga, J., Yamaki, S.B., Atvars, T.D.Z., (2003) Curr Org Chem, 7, p. 197Schurr, O., Yamaki, S.B., Wang, C.H., Atvars, T.D.Z., Weiss, R.G., (2003) Macromolecules, 36, p. 3485Baldi, L.D.C., Iamazaki, E.T., Atvars, T.D.Z., (2008) Dyes Pigments, 76, p. 669Iamazaki, E.T., Pereira-Da-Silva, M.A., Carvalho, A.J.F., Romero, R.B., Gonôalves, M.C., Atvars, T.D.Z., (2010) J Appl Polym Sci, p. 118. , electronic version available since junePinto, R., Amaral, A.L., Ferreira, E.C., Mota, M., Vilanova, M., Ruel, K., Gama, M., (2008) BMC Biotechnol, 8, p. 7Berns, R.S., Reiman, D.M., (2002) Col Res Appl, 27, p. 360Billmeyer Jr., F.W., Saltzman, M., (1981) Principles of Color Technology, , 2nd ed. Wiley-Interscience: New YorkSenthilkumar, A., (2007) Dyes Pig, 75, p. 356Imura, K., (2007) Color Res Appl, 32, p. 195Imura, K., (2007) Color Res Appl, 32, p. 449Smit, K.J., Ghiggino, K.P., (1991) J Polym Sci Part B-Polym Phys, 29, p. 1397Aloulou, F., Boufi, S., Belgacem, N., Gandini, A., (2004) Colloid Polym Sci, 283, p. 344Alila, S., Boufi, S., Belgacem, M.N., Beneventi, D., (2005) Langmuir, 21, p. 8106O'Haver, J.H., Harwell, J.H., (1995) Surfactant Adsorption and Surface Solubilization, p. 49. , Sharma, R. Ed.ACS Symposium Series 615, American Chemical Society: Washingto

Sorption Of A Fluorescent Whitening Agent (tinopal Cbs) Onto Modified Cellulose Fibers In The Presence Of Surfactants And Salt.

The combined effect of salt (10 mmol L(-1)) and surfactants on the sorption of the fluorescent brightener 4,4'-distyrylbiphenyl sodium sulfonate (Tinopal CBS) onto modified cellulose fibers was studied. Sorption efficiencies with both cationic and anionic surfactants were evaluated. Emission spectroscopy was used for quantitative analysis since Tinopal has an intense fluorescence. The sorption efficiency of the brightener is greater for solutions containing a cationic surfactant (DTAC) below the critical micelle concentration (cmc), while for an anionic surfactant (SDS) above its cmc the efficiency is greater. The profile of the sorption isotherms were interpreted in terms of the evolution of surfactant aggregation at the fiber/solution interface. Salt influences the efficiency of the Tinopal sorption on the modified cellulose fibers either because it decreases the cmc of the surfactants or because the ions screen the surface charges of the fiber which decreases the electrostatic interaction among the charged headgroup of the surfactant and the charged fiber surface.2312886-9

Role Of Surfactants In The Sorption Of The Whitening Agent Tinopal Cbs Onto Viscose Fibers: A Fluorescence Spectroscopy Study.

In the present work, we studied the role of an anionic surfactant, sodium dodecyl sulfate, and a cationic surfactant, dodecyltrimethylammonium chloride, in the sorption of 4,4'-distyrylbiphenyl sodium sulfonate (Tinopal CBS) onto modified cellulose fibers. Fluorescence spectroscopy was used to quantify the amount of sorbed Tinopal CBS on the fiber surface. Differences in the spectral properties and the efficiency of sorption of the whitener/surfactant/fiber system are explained in terms of electrostatic interactions. Our results also show that the sorption efficiency is greater for solutions containing cationic surfactants only below the critical micelle concentration, while anionic surfactants show a smooth influence on the sorption process.229866-7

Evaluation of the polarity of polyamide surfaces using the fluorescence emission of pyrene

This paper reports the static and dynamic fluorescence emission of pyrene sorbed onto the surface of 6 different polyamides classified in two categories: AB (polyamide-6 and -11) or AABB (polyamide-6,6, -6,9, -6,10 and -6,12). Pyrene is a well known fluorescent probe for the polarity evaluation of different media for which the ratio of intensities of the vibronic bands (I-1/I-3) decreases in less polar medium and the fluorescence decay from the singlet electronic excited state increases with decreasing polarity. The steady-state vibronic ratio I-1/I-3 of the pyrene fluorescence emission decreases with decreasing polarity for polyamides AB but for polyamides AABB, this ratio undergoes a significant decrease for polyamides-6,9 compared with -6,6 but remains almost constant for polyamides-6,10 and -6,12. This shows that the steady-state fluorescence of pyrene is only sensitive to the polarity of sorption sites whose dimensions are similar to the van der Waals radius of the molecule. In contrast, fluorescence decays decrease with decreasing polarity of the polyamide from tau(F) = 250 ns for polyamide-6,6 to tau(F) = 310 ns for polyamide-6,12 and thus this parameter is always sensitive to the polarity of the medium. We also discuss the advantages of these spectroscopic methodologies that include their applicability to samples without any further sample manipulation and which is independent of their form, powder, pellet or film, and of their thicknesses and sizes. (c) 2007 Elsevier Ltd. All rights reserved.76366967