Phase-resolved Photoacoustic Spectroscopy And Epr Investigation Of Mno2- And Coo-doped Soda-lime Glasses

A discussion on the use of the phase shifts of the photoacoustic signal of different constituents of a composite sample for resolving their individual spectra is presented. It is experimentally shown that as long as we are interested in a qualitative analysis the method is simple and fast. For a quantitative analysis in which the nonradiative relaxation time and the characteristic diffusion time within the optical-absorption depth are sought, the method presents some limitations. This is demonstrated using MnO2- and CoO-doped soda-lime silica glass samples. © 1989 The American Physical Society.40318801884CAS; Chinese Academy of Sciences; DFG; Chinese Academy of Sciences; NRF; Chinese Academy of Sciences; NSFC; Chinese Academy of Sciences; PSI; Chinese Academy of Sciences; RAS; Chinese Academy of Sciences; RFBR; Chinese Academy of Sciences; RPF; Chinese Academy of Sciences; STFC; Chinese Academy of Science

Photoacoustic And Esr Studies Of Iron-doped Soda-lime Glasses: Thermal Diffusivity

The photoacoustic technique is used to measure the thermal diffusivity of iron-doped soda-lime glasses. To explain the thermal diffusivity behavior as a function of the iron content in the samples, electron-spin-resonance data were used. It is concluded that the main reason for the observed changes in the thermal diffusivity is the ferric ion entering substitutionally at the Si4+ sites. © 1989 The American Physical Society.40117912791

Mucoadhesive emulgel systems containing curcumin for oral squamous cell carcinoma treatment: from pre-formulation to cytotoxicity in tissue-engineering oral mucosa

Current oral squamous cell carcinoma chemotherapies demonstrate off-target toxicity, which could be reduced by local delivery. Curcumin acts via many cellular targets to give anti-cancer properties; however the bioavailability is hindered by its physicochemical characteristics. The incorporation of curcumin into emulgel systems could be a promising approach for its solubilization and delivery. The aim of this work was to develop emulgel systems containing curcumin for the treatment of oral cancer. The emulgels containing curcumin were prepared with poloxamer 407, acrylic acid derivatives, oil phase (sesame oil or isopropyl myristate). The more stable system was evaluated for mechanical and rheological properties, as well as, the in vitro drug release profile, permeation and cytotoxic potential to oral mucosa models. The flow-throw system evidenced that the formulations could keep 5 min over porcine oral mucosa. Emulgel showed pseudoplastic behavior and a gelation temperature of 33°C, which ensure their higher consistency. In addition, 70% of the incorporated curcumin was released within 24 hours in an in vitro drug release study and could permeate porcine oral mucosa. Monolayers cultures and tissue-engineered models showed the selectivity of the drug and systems for tumor cells. The physicochemical properties, subsequent release and permeation of curcumin to selectivity kill cancer cells could be improved by the incorporation into emulgel systems

Design of a nanostructured mucoadhesive system containing curcumin for buccal application : from physicochemical to biological aspects

Mucoadhesive nanostructured systems comprising poloxamer 407 and Carbopol 974P® have already demonstrated good mucoadhesion, as well as improved mechanical and rheological properties. Curcumin displays excellent biological activity, mainly in oral squamous cancer; however, its physicochemical characteristics hinder its application. Therefore, the aim of this study was to develop nanostructured formulations containing curcumin for oral cancer therapy. The photophysical interactions between curcumin and the formulations were elucidated by incorporation kinetics and location studies. They revealed that the drug was quickly incorporated and located in the hydrophobic portion of nanometer-sized polymeric micelles. Moreover, the systems displayed plastic behavior with rheopexy characteristics at 37 °C, viscoelastic properties and a gelation temperature of 36 °C, which ensures increased retention after application in the oral cavity. The mucoadhesion results confirmed the previous findings with the nanostructured systems showing a residence time of 20 min in porcine oral mucosa under flow system conditions. Curcumin was released after 8 h and could permeate through the porcine oral mucosa. Cytotoxicity testing revealed that the formulations were selective to cancer cells over healthy cells. Therefore, these systems could improve the physicochemical characteristics of curcumin by providing improved release and permeation, while selectivity targeting cancer cells

Thermal Diffusivity Anisotropy In Calamitic-nematic Lyotropic Liquid Crystal

The temperature dependence of the thermal diffusivity of a lyotropic liquid crystal was studied using thermal lens technique. The sample under study was aligned in a magnetic field before measurements thus allowing the determination of the thermal diffusivity in both directions. The results show that the thermal diffusivity sharply decreases in the phase transition temperatures, and presents an anisotropy in the nematic phase.741 II822824Shen, J., Snook, R.D., (1993) J. Appl. Phys., 73, p. 5286Baesso, M.L., Shen, J., Snook, R.D., (1994) J. Appl. Phys., 75, p. 3732Bento, A.C., Palangana, A.J., Evangelista, L.R., Baesso, M.L., Pereira, J.R.D., Da Silva, E.C., Mansanares, A.M., (1996) Appl. Phys. Lett., 68, p. 3371Pereira, J.R.D., Mansanares, A.M., Palangana, A.J., Baesso, M.L., (1999) Mol. Cryst. Liq. Cryst., 332, p. 569Glorieux, C., Bozoki, Z., Fivez, J., Thoen, J., (1995) J. Appl. Phys., 78, p. 3096Mercuri, F., Zammit, U., Marinelli, M., (1998) Phys. Rev. E, 57, p. 596Touloukian, Y.S., Powel, R.W., Ho, C.Y., Nicolau, M.C., (1983) Thermal Properties of Matter, 10. , Plenum, New YorkGarlene, Y., Moarcerou, J.P., (1983) Phys. Rev. Lett., 51, p. 210

Fourier transform infrared photoacoustic spectroscopy to study the penetration of substances through skin

Step-scan Fourier Transform Inflared (FT-IR) Photoacoustic Spectroscopy (PAS) has been used to study the penetration of substances through abdominal pig skin. The experiments were performed in vitro and dimethylsulfoxide (DMSO) was applied either onto the surface or the bottom of the sample. The results demonstrated that DMSO propagated fast through the skin from the bottom surface. The ease of identification of this substance in this spectral range showed the potential of the technique, suggesting that penetration and distribution of other chemicals through the skin can be investigated by FT-IR PAS

A thermal lens study of undoped and Fe2O3-doped silicate glasses at different wavelengths

The mode mismatched thermal lens technique has been wed to determine the temperature coefficient of optical path length, ds/dT, of undoped and 2% Fe2O3-doped silicate glasses, at different wavelengths. The aberrant model, which takes into account the thickness change of the sample, was used as the theoretical model. The results showed that ds/dT is (2.1 ± 0.1) x 10-6 K-1 at 632.8 nm and (2.4 ± 0.1) x 10-6 K-1 at 442 nm for the undoped sample and (4.66 ± 0.03) x 10-6 K-1 at 632.8 nm and (6.1 ± 0.1) x 10-6 K-1 at 442 nm for the iron doped sample. The greater value of this parameter found for the doped sample at the Fe3+ absorption band (442 nm), was associated with the bigger value of the temperature coefficient of the electronic polarizability caused by the presence and environment of Fe3+ iron in the structure of the glass

Probe beam image detection for mode-mismatched dual beam thermal lens spectrometry

A model for CW induced mode-mismatched dual-beam thermal lens spectrometry using the whole probe beam profile has been developed. This model quantitatively describes the intensity distribution before and after the thermal lens has been created. It is considered that after passing through the thermal lens, the TM00 Gaussian probe beam becomes the superposition of several Gaussian beams of different parameters. A compact mathematical expression was obtained, which allows absolute measurements of opthothermal properties of transparent samples. Experimental proofs have been displayed

Thermo-optical Properties Of Oh-free Erbium-doped Low Silica Calcium Aluminosilicate Glasses Measured By Thermal Lens Technique

Thermal lens spectrometry (TLS) of thermo-optical properties of low silica content calcium aluminosilicate glasses (27.1 Al2O3, 58.1 CaO, 7.9 SiO2 and 6.9 MgO in mol%) was performed. The thermal diffusivity was 5.7 × 10-3 cm2/s for undoped sample and 4.7 × 10-3 cm2/s for 1.48 mol% Er2O3-doped one. The ds/dT for undoped samples was 8.6 ± 0.1 × 10-6 K-1. The thermal conductivity was around 14 mW/cm K with some dependence on Er2O3 concentration. The fraction of the absorbed energy converted into heat by Er2O3-doped samples was about 60%. © 2001 Elsevier Science B.V.2841-3210216Baesso, M.L., Bento, A.C., Andrade, A.A., Catunda, T., Sampaio, J.A., Gama, S., (1997) J. Non-Cryst. Solids, 219, p. 165Baesso, M.L., Shen, J., Snook, R.D., (1994) J. Appl. Phys., 75, p. 3232Baesso, M.L., Bento, A.C., Andrade, A.A., Sampaio, J.A., Pecoraro, E., Nunes, L.A.O., Catunda, T., (1998) Phys. Rev. B, 57, p. 10545Shen, J., Lowe, R.D., Snook, R.D., (1992) Chem. Phys., 165, p. 385Lima, S.M., Sampaio, J.A., Catunda, T., Lebullenger, R., Hernandes, A.C., Baesso, M.L., Bento, A.C., Gandra, F.C.G., (1999) J. Non-Cryst. Solids, 256-257, p. 337Weber, M.J., (1990) J. Non-Cryst. Solids, 123, p. 208Lucas, L., Chanthanasinh, M., Poulain, M., Brun, P., Weber, M.J., (1978) J. Non-Cryst. Solids, 27, p. 273Kohli, J.T., Shelby, J.E., (1991) Phys. Chem. Glasses, 32, p. 67Shelby, J.E., Kohli, J.T., (1990) J. Am. Ceram. Soc., 73, p. 39Shelby, J.E., (1985) J. Am. Ceram. Soc., 68, p. 155Higby, P.L., Ginther, R.J., Aggarwal, I.D., Friebele, E.J., (1990) J. Non-Cryst. Solids, 126, p. 209Tanabe, S., Ohyagi, T., Hanada, T., Soga, N., (1993) J. Ceram. Soc. Jpn., 101, p. 74Baesso, M.L., Bento, A.C., Duarte, A.R., Neto, A.M., Miranda, L.C.M., Sampaio, J.A., Catunda, T., Gandra, F.C.G., (1999) J. Appl. Phys., 85, p. 8112Sheperd, E.S., Rankin, G.A., Wright, F.E., (1909) Am. J. Sci., 28, p. 293Zou, X., Izumitani, T., (1993) J. Ceram. Soc. Jpn., 101, p. 80Zou, X., Izumitani, T., (1993) J. Ceram. Soc. Jpn., 101, p. 85Zou, X., Izumitani, T., (1993) J. Non-Cryst. Solids, 162, p. 68Uhlmann, E.V., Weinberg, M.C., Kreidl, N.J., Burgner, L.L., Zanoni, R., Church, K.H., (1994) J. Non-Cryst. Solids, 178, p. 15Kinoshita, T., Yamazaki, M., Kawazoe, H., Hosono, H., (1999) J. Appl. Phys., 86, p. 3729Hosono, H., Kinoshita, T., Kawazoe, H., (1998) J. Phys. Condens. Matter, 10, p. 9541De Souza, D.F., Zonetti, L.F.C., Bell, M.J.V., Sampaio, J.A., O. Nunes, L.A., Baesso, M.L., Bento, A.C., Miranda, L.C.M., (1999) Appl. Phys. Lett., 74, p. 908Digonnet, M.J.F., (1993) Rare-earth Doped Fibers Lasers and Amplifiers, , New York: Marcel DekkerMansanares, A.M., Baesso, M.L., Silva, E.C., Gandra, F.C.G., Vargas, H., Miranda, L.C.M., (1989) Phys. Rev. B, 40, p. 7912Hewak, D., (1993) Glass and Rare-Earth Doped Glasses for Optical Fibers, , Short Run Pres

Thermal Diffusivity Measurements In Lyotropic Ferronematics: Mode Mismatched Thermal Lens

The mode mismatched thermal lens technique was used in the determination of thermal diffusivity of oriented lyotropic liquid crystal doped with ferrofluid. It was found that the behavior of the parallel thermal diffusivity as a function of ferrofluid content could not be explained in terms of the order parameter alone. Additional contribution coming from the ferrofluid itself seems to be necessary for the interpretation of the experimental data.332569575Shen, J., Snook, R.D., (1993) J. Appl. Phys., 73, p. 5286Baesso, M.L., Shen, J., Snook, R.D., (1994) J. Appl. Phys., 75, p. 3732Bento, A.C., Palangana, A.J., Evangelista, L.R., Baesso, M.L., Pereira, J.R.D., Da Silva, E.C., Mansanares, A.M., (1996) Appl. Phys. Lett., 68, p. 3371Shibli, S.M., Dantas, A.L.L., Walton, D., (1998) Appl. Phys. Lett., 72, p. 674Mercuri, F., Zammit, U., Marinelli, M., (1998) Phys. Rev. E, 57, p. 59