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Sample records for thermal reversible microemulsion

  1. Thermal stability and microstructure characterization of MgAl{sub 2}O{sub 4} nanoparticles synthesized by reverse microemulsion method

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Ping; Lu, Wenzhong; Lei, Wen, E-mail: lwz@mail.hust.edu.cn [Department of Electronic Science and Technology, HuaZhong University of Science and Technology - HUST, Wuhan (China); Wu, Ke; Xu, Yong [Department of Materials Science and Engineering, Wuhan Institute of Technology - WIT, Wuhan (China); Wu, Jiamin [Key Lab of Functional Materials for Electronic Information(B) MOE, HuaZhong University of Science and Technology - HUST, Wuhan (China)

    2013-11-01

    Magnesium aluminate (MgAl{sub 2}O{sub 4}) spinel nanoparticles were synthesized by reverse microemulsion process in cyclohexane by using two kinds of surfactants, n-amyl alcohol as cosurfactant and mixture of aluminic/magnesic salt aqueous solution as basic reagents. The effects of surfactant types and titration methods on the morphologies and sizes of the MgAl{sub 2}O{sub 4} nanoparticles were characterized by TEM, TGA-DTA, XRD, HR-TEM and FT-IR. TEM images show that the particles prepared by forward titration method with SPAN-80/Triton X-100 compound emulsifier have uniform spherical shape and good monodispersity with an average size of 9.5 nm. However, the average size of the particles prepared by reverse-titration method was about 10 nm and some particles have irregular plate like appearance. The products prepared with NP-40 surfactant and forward-titration method were agglomerated with an average size of 13 nm. TGA and XRD results show that the reverse microemulsion method has dramatically lowered the calcination temperature of MgAl{sub 2}O{sub 4} with a degree of 700 Degree-Sign C, and the precursor can transform to single spinel phase at 900 Degree-Sign C. (author)

  2. Influence of polyethylene glycol on percolation dynamics of reverse microemulsions

    Science.gov (United States)

    Geethu, P. M.; Yadav, Indresh; Aswal, V. K.; Satapathy, D. K.

    2018-04-01

    We explore the influence of a hydrophilic polymer, polyethylene glycol (PEG), on the structure and the percolation dynamics of reverse microemulsions (ME) stabilized by an anionic surfactant AOT (sodium bis(2-ethylhexyl) sulfosuccinate). The percolation transition of MEs is probed using dielectric relaxation spectroscopy (DRS). Notably, an increase in percolation temperature is observed by the incorporation of PEG-polymer into larger ME droplets which is explained by considering the model of polymer adsorption at surfactant-water interface. The stability of the droplet phase of microemulsion after the incorporation of PEG is confirmed by small-angle neutron scattering (SANS) experiment. Further, a net decrease in percolation transition temperature is observed with the addition of PEG polymer for smaller ME droplets and is discussed in relation with the destabilization of droplets owing to the polymer induced bridging and the associated clustering of droplets. We conjecture that the adsorption of PEG polymer chains at the surfactant-water interface as well as the PEG-induced bridging of droplets are due to the strong ion-dipole interaction between anionic head group of AOT surfactant and dipoles present in PEG polymer chains.

  3. Highly efficient upconversion luminescence in hexagonal NaYF4:Yb3+, Er3+ nanocrystals synthesized by a novel reverse microemulsion method

    Science.gov (United States)

    Gunaseelan, M.; Yamini, S.; Kumar, G. A.; Senthilselvan, J.

    2018-01-01

    A new reverse microemulsion system is proposed for the first time to synthesize NaYF4:Yb,Er nanocrystals, which demonstrated high upconversion emission in 550 and 662 nm at 980 nm diode laser excitation. The reverse microemulsion (μEs) system is comprised of CTAB and oleic acid as surfactant and 1-butanol co-surfactant and isooctane oil phase. The surfactant to water ratio is able to tune the microemulsion droplet size from 14 to 220 nm, which eventually controls the crystallinity and particulate morphology of NaYF4:Yb,Er. Also, the microemulsion precursor and calcination temperature plays certain role in transforming the cubic NaYF4:Yb,Er to highly luminescent hexagonal crystal structured upconversion material. Single phase hexagonal NaYF4:YbEr nanorod prepared by water-in-oil reverse microemulsion (μEs) gives intense red upconversion emission. Both nanosphere and nanorod shaped NaYF4:Yb,Er was obtained, but nanorod morphology resulted an enhanced upconversion luminescence. The structural, morphological, thermal and optical luminescence properties of the NaYF4:Yb,Er nanoparticles are discussed in detail by employing powder X-ray diffraction, dynamic light scattering, high resolution electron microscopy, TGA-DTA, UV-DRS, FTIR and photoluminescence spectroscopy. Intense upconversion emission achieved in the microemulsion synthesized NaYF4:Yb3+,Er3+ nanocrystal can make it as useful optical phosphor for solar cell applications.

  4. Reverse microemulsion synthesis of layered gadolinium hydroxide nanoparticles

    Science.gov (United States)

    Xu, Yadong; Suthar, Jugal; Egbu, Raphael; Weston, Andrew J.; Fogg, Andrew M.; Williams, Gareth R.

    2018-02-01

    A reverse microemulsion approach has been explored for the synthesis of layered gadolinium hydroxide (LGdH) nanoparticles in this work. This method uses oleylamine as a multifunctional agent, acting as surfactant, oil phase and base. 1-butanol is additionally used as a co-surfactant. A systematic study of the key reaction parameters was undertaken, including the volume ratio of surfactant (oleylamine) to water, the reaction time, synthesis temperature, and the amount of co-surfactant (1-butanol) added. It proved possible to obtain pristine LGdH materials at temperatures of 120 °C or below with an oleylamine: water ratio of 1:4. Using larger amounts of surfactant or higher temperatures caused the formation of Gd(OH)3, either as the sole product or as a major impurity phase. The LGdH particles produced have sizes of ca. 200 nm, with this size being largely independent of temperature or reaction time. Adjusting the amount of 1-butanol co-surfactant added permits the size to be varied between 200 and 300 nm.

  5. Synthesis of Brushite Particles in Reverse Microemulsions of the Biosurfactant Surfactin

    Directory of Open Access Journals (Sweden)

    Young-Fo Chang

    2011-06-01

    Full Text Available In this study the “green chemistry” use of the biosurfactant surfactin for the synthesis of calcium phosphate using the reverse microemulsion technique was demonstrated. Calcium phosphates are bioactive materials that are a major constituent of human teeth and bone tissue. A reverse microemulsion technique with surfactin was used to produce nanocrystalline brushite particles. Structural diversity (analyzed by SEM and TEM resulted from different water to surfactin ratios (W/S; 250, 500, 1000 and 40,000. The particle sizes were found to be in the 16–200 nm range. Morphological variety was observed in the as-synthesized microemulsions, which consisted of nanospheres (~16 nm in diameter and needle-like (8–14 nm in diameter and 80–100 nm in length noncalcinated particles. However, the calcinated products included nanospheres (50–200 nm in diameter, oval (~300 nm in diameter and nanorod (200–400 nm in length particles. FTIR and XRD analysis confirmed the formation of brushite nanoparticles in the as-synthesized products, while calcium pyrophosphate was produced after calcination. These results indicate that the reverse microemulsion technique using surfactin is a green process suitable for the synthesis of nanoparticles.

  6. Synthesis of brushite particles in reverse microemulsions of the biosurfactant surfactin.

    Science.gov (United States)

    Maity, Jyoti Prakash; Lin, Tz-Jiun; Cheng, Henry Pai-Heng; Chen, Chien-Yen; Reddy, A Satyanarayana; Atla, Shashi B; Chang, Young-Fo; Chen, Hau-Ren; Chen, Chien-Cheng

    2011-01-01

    In this study the "green chemistry" use of the biosurfactant surfactin for the synthesis of calcium phosphate using the reverse microemulsion technique was demonstrated. Calcium phosphates are bioactive materials that are a major constituent of human teeth and bone tissue. A reverse microemulsion technique with surfactin was used to produce nanocrystalline brushite particles. Structural diversity (analyzed by SEM and TEM) resulted from different water to surfactin ratios (W/S; 250, 500, 1000 and 40,000). The particle sizes were found to be in the 16-200 nm range. Morphological variety was observed in the as-synthesized microemulsions, which consisted of nanospheres (~16 nm in diameter) and needle-like (8-14 nm in diameter and 80-100 nm in length) noncalcinated particles. However, the calcinated products included nanospheres (50-200 nm in diameter), oval (~300 nm in diameter) and nanorod (200-400 nm in length) particles. FTIR and XRD analysis confirmed the formation of brushite nanoparticles in the as-synthesized products, while calcium pyrophosphate was produced after calcination. These results indicate that the reverse microemulsion technique using surfactin is a green process suitable for the synthesis of nanoparticles.

  7. Polyaniline/silver nanocomposites synthesized via UV-Vis-Assisted aniline polymerization with a reversed micellar microemulsion system

    NARCIS (Netherlands)

    Li, Z.; Li, Y.; Lin, W.; Zheng, F.; Laven, J.

    Polyaniline (PANI)/silver (Ag) nanocomposites were successfully synthesized within a sodium dodecyl sulfate reverse micro-emulsion system and characterized by Fourier transform infrared spectroscopy, X-ray diffraction, ultraviolet spectrometry, thermogravimetric analysis, scanning electron

  8. Preparation of ultrasmall porous carbon nanospheres by reverse microemulsion-hydrothermal method

    Science.gov (United States)

    Wang, Jiasheng; Zhao, Yahong; Wang, Wan-Hui; Bao, Ming

    Porous carbon nanospheres (CNSs) have wide applications. A big challenge in materials science is synthesis of discrete ultrasmall porous carbon nanospheres. Herein, we report a facile reverse microemulsion-hydrothermal method to prepare discrete porous CNSs. The obtained CNSs possess an average diameter of 20nm and pores of 0.7nm and 3.4nm. Our work has provided a convenient method for the controllable synthesis of ultrasmall porous CNSs with potential applications.

  9. Reverse microemulsion prepared Ni–Pt catalysts for methane cracking to produce COx-free hydrogen

    KAUST Repository

    Zhou, Lu

    2017-09-08

    A monodispersed 15 nm Ni9Pt1 catalyst synthesized via a reverse microemulsion method, shows a lower activation energy than both Ni and Pt catalysts during the methane cracking reaction. Thanks to the synergic effect of Ni–Pt alloy, this catalyst presents a stable H2 formation rate at 700 °C, and forms carbon nanotubes, anchoring the catalyst particles on top.

  10. Reverse microemulsion prepared Ni–Pt catalysts for methane cracking to produce COx-free hydrogen

    KAUST Repository

    Zhou, Lu; Harb, Moussab; Enakonda, Linga Reddy; Al Mana, Noor; Hedhili, Mohamed N.; Basset, Jean-Marie

    2017-01-01

    A monodispersed 15 nm Ni9Pt1 catalyst synthesized via a reverse microemulsion method, shows a lower activation energy than both Ni and Pt catalysts during the methane cracking reaction. Thanks to the synergic effect of Ni–Pt alloy, this catalyst presents a stable H2 formation rate at 700 °C, and forms carbon nanotubes, anchoring the catalyst particles on top.

  11. Chitosan-Coated Magnetic Nanoparticles Prepared in One Step by Reverse Microemulsion Precipitation

    OpenAIRE

    Hened Saade; Salvador Fernández; Ramón Díaz de León; Gilberto Hurtado; María G. Pineda; Raúl G. López; Darío Bueno

    2013-01-01

    Chitosan-coated magnetic nanoparticles (CMNP) were obtained at 70 ?C and 80 ?C in a one-step method, which comprises precipitation in reverse microemulsion in the presence of low chitosan concentration in the aqueous phase. X-ray diffractometry showed that CMNP obtained at both temperatures contain a mixture of magnetite and maghemite nanoparticles with ?4.5 nm in average diameter, determined by electron microscopy, which suggests that precipitation temperature does not affect the particle si...

  12. Preparation and self-assembly of nanostructured BaCrO4 from CTAB reverse microemulsions

    International Nuclear Information System (INIS)

    Li Zhonghao; Zhang Jianling; Du Jimin; Han Buxing; Mu Tiancheng; Gao Yanan; Liu Zhimin

    2005-01-01

    Well-defined superstructures of rectangular-shaped BaCrO 4 and extensive network of BaCrO 4 nanoparticles constructed by self-assembly were prepared in cetyltrimethylammonium bromide (CTAB) reverse microemulsions. The effects of aging time and reactant concentrations on the morphology and the self-assemble pattern of the nanostructured BaCrO 4 were investigated. TEM combined with the electron diffraction was used to characterize the morphology and the crystal structure of the prepared nanostructured BaCrO 4 at different conditions

  13. Chitosan-coated magnetic nanoparticles prepared in one step by reverse microemulsion precipitation.

    Science.gov (United States)

    López, Raúl G; Pineda, María G; Hurtado, Gilberto; León, Ramón Díaz de; Fernández, Salvador; Saade, Hened; Bueno, Darío

    2013-09-27

    Chitosan-coated magnetic nanoparticles (CMNP) were obtained at 70 °C and 80 °C in a one-step method, which comprises precipitation in reverse microemulsion in the presence of low chitosan concentration in the aqueous phase. X-ray diffractometry showed that CMNP obtained at both temperatures contain a mixture of magnetite and maghemite nanoparticles with ≈4.5 nm in average diameter, determined by electron microscopy, which suggests that precipitation temperature does not affect the particle size. The chitosan coating on nanoparticles was inferred from Fourier transform infrared spectrometry measurements; furthermore, the carbon concentration in the nanoparticles allowed an estimation of chitosan content in CMNP of 6%-7%. CMNP exhibit a superparamagnetic behavior with relatively high final magnetization values (≈49-53 emu/g) at 20 kOe and room temperature, probably due to a higher magnetite content in the mixture of magnetic nanoparticles. In addition, a slight direct effect of precipitation temperature on magnetization was identified, which was ascribed to a possible higher degree of nanoparticles crystallinity as temperature at which they are obtained increases. Tested for Pb2+ removal from a Pb(NO3)2 aqueous solution, CMNP showed a recovery efficacy of 100%, which makes them attractive for using in heavy metals ion removal from waste water.

  14. Synthesis of highly fluorescent silica nanoparticles in a reverse microemulsion through double-layered doping of organic fluorophores

    International Nuclear Information System (INIS)

    Yoo, Hyojong; Pak, Joonsung

    2013-01-01

    Water-soluble, highly fluorescent double-layered silica nanoparticles (FL-DLSN) have been successfully synthesized through a reverse (water-in-oil) microemulsion method. The microemulsion was prepared by mixing a surfactant (Brij35), co-surfactant, organic solvent, water, and fluorescein as an organic fluorophore. The sizes of the silica nanoparticles were successfully controlled in the reverse microemulsion using Brij35 by changing the water-to-Brij35 ratio and by adding HCl. Initially, tetraethylorthosilicate was hydrolyzed by adding NH 4 OH as a catalyst and then polymerized to generate core fluorescent silica nanoparticles with fluorescein. 3-(Aminopropyl)triethoxysilane (APTS) was sequentially added into the reaction mixture, and reacted on the surface of pre-generated core silica nanoparticles to form the second layer in the form of a shell. The second silica layer that was derived from the condensation of APTS effectively protected the fluorescein dye within the silica matrix. This is a novel and simple synthetic approach to generate highly fluorescent, monodispersed silica nanoparticles by doping organic molecules into a silica matrix.Graphical Abstract

  15. Synthesis of highly fluorescent silica nanoparticles in a reverse microemulsion through double-layered doping of organic fluorophores

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Hyojong, E-mail: hyojong@hallym.ac.kr; Pak, Joonsung [Hallym University, Department of Chemistry (Korea, Republic of)

    2013-05-15

    Water-soluble, highly fluorescent double-layered silica nanoparticles (FL-DLSN) have been successfully synthesized through a reverse (water-in-oil) microemulsion method. The microemulsion was prepared by mixing a surfactant (Brij35), co-surfactant, organic solvent, water, and fluorescein as an organic fluorophore. The sizes of the silica nanoparticles were successfully controlled in the reverse microemulsion using Brij35 by changing the water-to-Brij35 ratio and by adding HCl. Initially, tetraethylorthosilicate was hydrolyzed by adding NH{sub 4}OH as a catalyst and then polymerized to generate core fluorescent silica nanoparticles with fluorescein. 3-(Aminopropyl)triethoxysilane (APTS) was sequentially added into the reaction mixture, and reacted on the surface of pre-generated core silica nanoparticles to form the second layer in the form of a shell. The second silica layer that was derived from the condensation of APTS effectively protected the fluorescein dye within the silica matrix. This is a novel and simple synthetic approach to generate highly fluorescent, monodispersed silica nanoparticles by doping organic molecules into a silica matrix.Graphical Abstract.

  16. Synthesis and characterization of α-NaYF{sub 4}: Yb, Er nanoparticles by reverse microemulsion method

    Energy Technology Data Exchange (ETDEWEB)

    Gunaseelan, M.; Senthilselvan, J., E-mail: jsselvan@hotmail.com [Department of Nuclear Physics, University of Madras, Chennai, Tamil Nadu (India)

    2016-05-06

    A simple and cost effective reverse microemulsion system was newly designed to synthesis NaYF{sub 4}:20%Yb,2%Er upconverting luminescent nanoparticles. XRD results confirms the cubic structure of NaYF{sub 4} nanophosphor in the as prepared condition without any other impurity phases. The as-prepared sample itself having highly crystalline nanoparticle with well dispersed uniform morphology is the advantage of this reverse microemulsion process. HRTEM images of as prepared and calcined samples revealed spherical nanoclusters morphology with size of ~210 nm and ~245 nm respectively. The characteristic absorption wavelength that occurs at 980 nm due to transition of energy levels {sup 2}F{sub 5/2} to {sup 2}F{sub 7/2} for Yb{sup 3+} rare earth ion in as prepared and calcined upconversion nanoparticle confirms the presence of Yb{sup 3+} by UV-Visible spectroscopy which can act as a sensitizer for photonic upconversion. Therefore the absorption at NIR region and emission spectrum at visible region suggests that NaYF{sub 4}:20%Yb,2%Er is suitable for upcoversion process, due to its optical property and chemical stability this material also be useful for bio imaging applications.

  17. Design of a core–shell Pt–SiO2 catalyst in a reverse microemulsion system: Distinctive kinetics on CO oxidation at low temperature

    KAUST Repository

    Al Mana, Noor; Phivilay, Somphonh Peter; Laveille, Paco; Hedhili, Mohamed N.; Fornasiero, Paolo; Takanabe, Kazuhiro; Basset, Jean-Marie

    2016-01-01

    The mechanism of formation of Pt@SiO2 as a model of core–shell nanoparticles via water-in-oil reverse microemulsions was studied in detail. By controlling the time of growth of Pt precursors, Pt(OH)x, after hydrolysis in NH3 aq. before adding SiO2

  18. Low-Temperature Reverse Microemulsion Synthesis, Characterization, and Photocatalytic Performance of Nanocrystalline Titanium Dioxide

    Directory of Open Access Journals (Sweden)

    Zhang Liu

    2012-01-01

    Full Text Available Nanocrystalline titanium dioxide (TiO2 was synthesized in microemulsions by using cetyltrimethylammonium bromide (CTAB as surfactant. In order to investigate the crystal transformation and photoactivity at low temperature, the as-prepared precipitates were aged at 65°C or calcined at various temperatures. Analyses using powder X-ray diffraction (XRD and Fourier transform infrared microscopy (FT-IR showed that precursors without aging or calcination were noncrystal and adsorbed by surfactant. After aging for 6 h, the amorphous TiO2 began to change into anatase. The obtained catalysts, which were synthesized in microemulsions with weight ratios of n-hexanol/CTAB/water as 6 : 3 : 1 and calcined at 500°C, presented the highest photocatalytic degradation rate on methyl orange (MO, while the catalysts, which were aged at 65°C for 90 h, also exhibited an outstanding photocatalytic performance and a little higher than that of the commercial titania photocatalyst Degussa P25.

  19. Methods to synthesize NiPt bimetallic nanoparticles by a reversed-phase microemulsion, deposition of NiPt bimetallic nanoparticles on a support, and application of the supported catalyst for CO.sub.2 reforming of methane

    KAUST Repository

    Biausque, Gregory; Laveille, Paco; Anjum, Dalaver H.; Caps, Valerie; Basset, Jean-Marie

    2015-01-01

    Methods to synthesize NiPt bimetallic nanoparticles by a reversed-phase microemulsion, deposition of NiPt bimetallic nanoparticles on a support, and application of the supported catalyst for CO.sub.2 reforming of methane

  20. Methods to synthesize NiPt bimetallic nanoparticles by a reversed-phase microemulsion, deposition of NiPt bimetallic nanoparticles on a support, and application of the supported catalyst for CO.sub.2 reforming of methane

    KAUST Repository

    Biausque, Gregory

    2015-04-28

    Methods to synthesize NiPt bimetallic nanoparticles by a reversed-phase microemulsion, deposition of NiPt bimetallic nanoparticles on a support, and application of the supported catalyst for CO.sub.2 reforming of methane

  1. Chitosan-coated magnetic nanoparticles prepared in one-step by precipitation in a high-aqueous phase content reverse microemulsion.

    Science.gov (United States)

    Pineda, María Guadalupe; Torres, Silvia; López, Luis Valencia; Enríquez-Medrano, Francisco Javier; de León, Ramón Díaz; Fernández, Salvador; Saade, Hened; López, Raúl Guillermo

    2014-07-02

    Chitosan-coated magnetic nanoparticles (CMNP) were prepared in one-step by precipitation in a high-aqueous phase content reverse microemulsion in the presence of chitosan. The high-aqueous phase concentration led to productivities close to 0.49 g CMNP/100 g microemulsion; much higher than those characteristic of precipitation in reverse microemulsions for preparing magnetic nanoparticles. The obtained nanoparticles present a narrow particle size distribution with an average diameter of 4.5 nm; appearing to be formed of a single crystallite; furthermore they present superparamagnetism and high magnetization values; close to 49 emu/g. Characterization of CMNP suggests that chitosan is present as a non-homogeneous very thin layer; which explains the slight reduction in the magnetization value of CMNP in comparison with that of uncoated magnetic nanoparticles. The prepared nanoparticles show high heavy ion removal capability; as demonstrated by their use in the treatment of Pb2+ aqueous solutions; from which lead ions were completely removed within 10 min.

  2. Chitosan-Coated Magnetic Nanoparticles Prepared in One-Step by Precipitation in a High-Aqueous Phase Content Reverse Microemulsion

    Directory of Open Access Journals (Sweden)

    María Guadalupe Pineda

    2014-07-01

    Full Text Available Chitosan-coated magnetic nanoparticles (CMNP were prepared in one-step by precipitation in a high-aqueous phase content reverse microemulsion in the presence of chitosan. The high-aqueous phase concentration led to productivities close to 0.49 g CMNP/100 g microemulsion; much higher than those characteristic of precipitation in reverse microemulsions for preparing magnetic nanoparticles. The obtained nanoparticles present a narrow particle size distribution with an average diameter of 4.5 nm; appearing to be formed of a single crystallite; furthermore they present superparamagnetism and high magnetization values; close to 49 emu/g. Characterization of CMNP suggests that chitosan is present as a non-homogeneous very thin layer; which explains the slight reduction in the magnetization value of CMNP in comparison with that of uncoated magnetic nanoparticles. The prepared nanoparticles show high heavy ion removal capability; as demonstrated by their use in the treatment of Pb2+ aqueous solutions; from which lead ions were completely removed within 10 min.

  3. Zero field reversal probability in thermally assisted magnetization reversal

    Science.gov (United States)

    Prasetya, E. B.; Utari; Purnama, B.

    2017-11-01

    This paper discussed about zero field reversal probability in thermally assisted magnetization reversal (TAMR). Appearance of reversal probability in zero field investigated through micromagnetic simulation by solving stochastic Landau-Lifshitz-Gibert (LLG). The perpendicularly anisotropy magnetic dot of 50×50×20 nm3 is considered as single cell magnetic storage of magnetic random acces memory (MRAM). Thermally assisted magnetization reversal was performed by cooling writing process from near/almost Curie point to room temperature on 20 times runs for different randomly magnetized state. The results show that the probability reversal under zero magnetic field decreased with the increase of the energy barrier. The zero-field probability switching of 55% attained for energy barrier of 60 k B T and the reversal probability become zero noted at energy barrier of 2348 k B T. The higest zero-field switching probability of 55% attained for energy barrier of 60 k B T which corespond to magnetif field of 150 Oe for switching.

  4. Design of Embedded Metal Catalysts via Reverser Micro-Emulsion System: a Way to Suppress Catalyst Deactivation by Metal Sintering

    KAUST Repository

    AlMana, Noor

    2016-06-19

    The development of highly selective and active, long-lasting, robust, low-cost and environmentally benign catalytic materials is the greatest challenge in the area of catalysis study. In this context, core-shell structures where the active sites are embedded inside the protecting shell have attracted a lot of researchers working in the field of catalysis owing to their enhanced physical and chemical properties suppress catalyst deactivation. Also, a new active site generated at the interface between the core and shell may increases the activity and efficiency of the catalyst in catalytic reactions especially for oxide shells that exhibit redox properties such as TiO2 and CeO2. Moreover, coating oxide layer over metal nanoparticles (NPs) can be designed to provide porosity (micropore/mesopore) that gives selectivity of the various reactants by the different gas diffusion rates. In this thesis, we will discuss the concept of catalyst stabilization against metal sintering by a core-shell system. In particular we will study the mechanistic of forming core-shell particles and the key parameters that can influence the properties and morphology of the Pt metal particle core and SiO2 shell (Pt@SiO2) using the reverse micro-emulsion method. The Pt@SiO2 core-shell catalysts were investigated for low-temperature CO oxidation reaction. The study was further extended to other catalytic applications by varying the composition of the core as well as the chemical nature of the shell material. The Pt NPs were embedded within another oxide matrix such as ZrO2 and TiO2 for CO oxidation reaction. These materials were studied in details to identify the factors governing the coating of the oxide around the metal NPs. Next, a more challenging system, namely, bimetallic Ni9Pt NPs embedded in TiO2 and ZrO2 matrix were investigated for dry reforming of methane reaction at high temperatures. The challenges of designing Ni9Pt@oxide core-shell structure with TiO2 and ZrO2 and their tolerance

  5. Electrodeposition of mesoscopic Pt-Ru on reticulated vitreous carbon from reverse emulsions and microemulsions: Application to methanol electro-oxidation

    International Nuclear Information System (INIS)

    Cheng, Tommy T.; Gyenge, Elod L.

    2006-01-01

    High surface area Pt-Ru (between 120 and 400 cm 2 mg -1 ) meso-sized particles and mesoporous coatings were electrodeposited on reticulated vitreous carbon (RVC) three-dimensional electrodes using reverse emulsions and microemulsions. The organic phase of the colloidal media was composed of cyclohexane, Triton X-100 non-ionic surfactant and tetrabutylammonium perchlorate (for ionic conductivity) while the aqueous phase contained H 2 PtCl 6 and RuCl 3 (or (NH 4 ) 2 RuCl 6 ). For microemulsification to occur isopropanol was also added as co-surfactant. The catalytic activity for the electro-oxidation of methanol was assessed by cyclic voltammetry and chronopotentiometry in conjunction with surface area measurement by Cu underpotential deposition. The composition and morphology of the Pt-Ru deposit was analyzed by inductively coupled plasma atomic emission spectroscopy and scanning electron microscopy, respectively. The effects on the catalytic activity of the deposition current density, temperature, RVC pretreatment and plating bath composition are presented. It was found that the electrodeposition of Pt-Ru in reverse microemulsion yielded the highest specific surface area (400 cm 2 mg -1 ) and catalytic activity toward CH 3 OH electro-oxidation as shown, for example, by a 50-200 mV more negative anode potential determined by chronopotentiometry compared to a catalyst obtained by pure aqueous and emulsion electroplating

  6. Electrodeposition of mesoscopic Pt-Ru on reticulated vitreous carbon from reverse emulsions and microemulsions: Application to methanol electro-oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Tommy T. [2360 East Mall, Department of Chemical and Biological Engineering, University of British Columbia, Vancouver, BC, V6T 1Z3 (Canada); Gyenge, Elod L. [2360 East Mall, Department of Chemical and Biological Engineering, University of British Columbia, Vancouver, BC, V6T 1Z3 (Canada)]. E-mail: egyenge@chml.ubc.ca

    2006-05-20

    High surface area Pt-Ru (between 120 and 400 cm{sup 2} mg{sup -1}) meso-sized particles and mesoporous coatings were electrodeposited on reticulated vitreous carbon (RVC) three-dimensional electrodes using reverse emulsions and microemulsions. The organic phase of the colloidal media was composed of cyclohexane, Triton X-100 non-ionic surfactant and tetrabutylammonium perchlorate (for ionic conductivity) while the aqueous phase contained H{sub 2}PtCl{sub 6} and RuCl{sub 3} (or (NH{sub 4}){sub 2}RuCl{sub 6}). For microemulsification to occur isopropanol was also added as co-surfactant. The catalytic activity for the electro-oxidation of methanol was assessed by cyclic voltammetry and chronopotentiometry in conjunction with surface area measurement by Cu underpotential deposition. The composition and morphology of the Pt-Ru deposit was analyzed by inductively coupled plasma atomic emission spectroscopy and scanning electron microscopy, respectively. The effects on the catalytic activity of the deposition current density, temperature, RVC pretreatment and plating bath composition are presented. It was found that the electrodeposition of Pt-Ru in reverse microemulsion yielded the highest specific surface area (400 cm{sup 2} mg{sup -1}) and catalytic activity toward CH{sub 3}OH electro-oxidation as shown, for example, by a 50-200 mV more negative anode potential determined by chronopotentiometry compared to a catalyst obtained by pure aqueous and emulsion electroplating.

  7. Size Control of Iron Oxide Nanoparticles Using Reverse Microemulsion Method: Morphology, Reduction, and Catalytic Activity in CO Hydrogenation

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Housaindokht

    2013-01-01

    Full Text Available Iron oxide nanoparticles were prepared by microemulsion method and evaluated in Fischer-Tropsch synthesis. The precipitation process was performed in a single-phase microemulsion operating region. Different HLB values of surfactant were prepared by mixing of sodium dodecyl sulfate (SDS and Triton X-100. Transmission electron microscopy (TEM, surface area, pore volume, average pore diameter, pore size distribution, and XRD patterns were used to analyze size distribution, shape, and structure of precipitated hematite nanoparticles. Furthermore, temperature programmed reduction (TPR and catalytic activity in CO hydrogenation were implemented to assess the performance of the samples. It was found that methane and CO2 selectivity and also the syngas conversion increased as the HLB value of surfactant decreased. In addition, the selectivity to heavy hydrocarbons and chain growth probability (α decreased by decreasing the catalyst crystal size.

  8. Two-step preparation of nano-scaled magnetic chitosan particles using Triton X-100 reversed-phase water-in-oil microemulsion system

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Zhengkun; Jiang, Feihong [College of Food Science and Engineering, Northwest A and F University, Yangling, Shaanxi 712100 (China); Lee, Tung-Ching, E-mail: lee@aesop.rutgers.edu [Department of Food Science, Rutgers, the State University of New Jersey, 65 Dudley Road, New Brunswick, NJ 08901 (United States); Yue, Tianli, E-mail: yuetl305@nwsuaf.edu.cn [College of Food Science and Engineering, Northwest A and F University, Yangling, Shaanxi 712100 (China)

    2013-12-25

    Highlights: •A new two-step route for nano-scaled magnetic chitosan particles preparation. •Triton X-100 reversed-phase microemulsion system was used for chitosan coating. •Narrow size distribution of magnetic chitosan nanoparticles was achieved. •Quantitative evaluation of recoverability for the magnetic chitosan nanoparticles. -- Abstract: A new two-step route for the preparation of nano-scaled magnetic chitosan particles has been developed, different from reported one-step in situ preparation and two-step preparation method of reversed-phase suspension, Triton X-100 reversed-phase water-in-oil microemulsion encapsulation method was employed in coating the pre-prepared Fe{sub 3}O{sub 4} nanoparticles with chitosan. The resultant magnetic chitosan particles owned a narrow size distribution ranging from 50 to 92 nm. X-ray diffraction patterns (XRD) indicated that the chitosan coating procedure did not change the spinal structure of Fe{sub 3}O{sub 4} magnetic nanoparticles. The results of Fourier transform infrared (FTIR) analysis and thermogravimetric analysis (TGA) demonstrated that the chitosan was coated on Fe{sub 3}O{sub 4} nanoparticles and its average mass content was ∼50%. The saturated magnetization of the magnetic Fe{sub 3}O{sub 4}/chitosan nanoparticles reached 18.62 emu/g, meanwhile, the nanoparticles showed the characteristics of superparamagnetism. The magnetic chitosan nanoparticles showed a high recoverability of 99.99% in 10 min when pH exceeded 4. The results suggested that the as-prepared magnetic chitosan particles were nano-scaled with a narrow size distribution and a high recoverability.

  9. Two-step preparation of nano-scaled magnetic chitosan particles using Triton X-100 reversed-phase water-in-oil microemulsion system

    International Nuclear Information System (INIS)

    Zhou, Zhengkun; Jiang, Feihong; Lee, Tung-Ching; Yue, Tianli

    2013-01-01

    Highlights: •A new two-step route for nano-scaled magnetic chitosan particles preparation. •Triton X-100 reversed-phase microemulsion system was used for chitosan coating. •Narrow size distribution of magnetic chitosan nanoparticles was achieved. •Quantitative evaluation of recoverability for the magnetic chitosan nanoparticles. -- Abstract: A new two-step route for the preparation of nano-scaled magnetic chitosan particles has been developed, different from reported one-step in situ preparation and two-step preparation method of reversed-phase suspension, Triton X-100 reversed-phase water-in-oil microemulsion encapsulation method was employed in coating the pre-prepared Fe 3 O 4 nanoparticles with chitosan. The resultant magnetic chitosan particles owned a narrow size distribution ranging from 50 to 92 nm. X-ray diffraction patterns (XRD) indicated that the chitosan coating procedure did not change the spinal structure of Fe 3 O 4 magnetic nanoparticles. The results of Fourier transform infrared (FTIR) analysis and thermogravimetric analysis (TGA) demonstrated that the chitosan was coated on Fe 3 O 4 nanoparticles and its average mass content was ∼50%. The saturated magnetization of the magnetic Fe 3 O 4 /chitosan nanoparticles reached 18.62 emu/g, meanwhile, the nanoparticles showed the characteristics of superparamagnetism. The magnetic chitosan nanoparticles showed a high recoverability of 99.99% in 10 min when pH exceeded 4. The results suggested that the as-prepared magnetic chitosan particles were nano-scaled with a narrow size distribution and a high recoverability

  10. One-Pot Synthesis of Size- and Composition-Controlled Ni-Rich NiPt Alloy Nanoparticles in a Reverse Microemulsion System and Their Application

    KAUST Repository

    Biausque, Gregory

    2017-08-16

    Bimetallic nanoparticles have been the subject of numerous research studies in the nanotechnology field, in particular for catalytic applications. Control of the size, morphology, and composition has become a key challenge due to the relationship between these parameters and the catalytic behavior of the particles in terms of activity, selectivity, and stability. Here, we present a one-pot air synthesis of 2 nm NiPt nanoparticles with a narrow size distribution. Control of the size and composition of the alloy particles is achieved at ambient temperature, in the aqueous phase, by the simultaneous reduction of nickel and platinum precursors with hydrazine, using a reverse microemulsion system. After deposition on an alumina support, this Ni-rich nanoalloy exhibits unprecedented stability under the harsh conditions of methane dry reforming.

  11. One-Pot Synthesis of Size- and Composition-Controlled Ni-Rich NiPt Alloy Nanoparticles in a Reverse Microemulsion System and Their Application

    KAUST Repository

    Biausque, Gregory; Laveille, Paco; Anjum, Dalaver H.; Zhang, Bei; Zhang, Xixiang; Caps, Valerie; Basset, Jean-Marie

    2017-01-01

    Bimetallic nanoparticles have been the subject of numerous research studies in the nanotechnology field, in particular for catalytic applications. Control of the size, morphology, and composition has become a key challenge due to the relationship between these parameters and the catalytic behavior of the particles in terms of activity, selectivity, and stability. Here, we present a one-pot air synthesis of 2 nm NiPt nanoparticles with a narrow size distribution. Control of the size and composition of the alloy particles is achieved at ambient temperature, in the aqueous phase, by the simultaneous reduction of nickel and platinum precursors with hydrazine, using a reverse microemulsion system. After deposition on an alumina support, this Ni-rich nanoalloy exhibits unprecedented stability under the harsh conditions of methane dry reforming.

  12. Magnetic properties of iron-based soft magnetic composites with SiO{sub 2} coating obtained by reverse microemulsion method

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Shen [School of Material Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Sun, Aizhi, E-mail: sunaizhi@126.com [School of Material Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Lu, Zhenwen; Cheng, Chuan [School of Material Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Gao, Xuexu [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China)

    2015-05-01

    In this work, iron-based soft magnetic composites coated with the amorphous SiO{sub 2} layer have been fabricated by utilizing tetraethoxysilane in the reverse microemulsion method, and then the effects of addition amount of SiO{sub 2} and annealing temperature on the magnetic properties were investigated. The results show that the surface of iron powders contains a thin amorphous SiO{sub 2} insulation layer, which effectively decreases the magnetic loss of synthesized magnets. The magnetic loss of coated samples decreased by 87.8% as compared with that of uncoated samples at 150 kHz. Magnetic measurements show that the sample with 1.25 wt% SiO{sub 2} has an acceptable real part and minimum imaginary part of permeability in comparison with other samples. Also, the annealing treatment increased the initial permeability, the maximum permeability and the magnetic induction and decreased the coercivity with increasing temperature in the range 300–600 °C. The results of the loss separation imply that the annealed SMCs have a higher hysteresis loss coefficient (k{sub 2}) and lower eddy current loss coefficient (k{sub 3}) as compared with the pure iron compacts after the same heat treatment due to the preservation of the SiO{sub 2} layer. - Highlights: • SiO{sub 2} coated the iron powder by reverse microemulsion method, decreased the magnetic loss of SMCs. • 25 wt% is the optimum coating amount to attain the desired permeability. • The influence of annealing temperature on the magnetic performance of the core was discussed. • Compare with the pure iron compacts, the annealed SMCs have lower value of eddy current coefficient.

  13. Reclaimable Thermally Reversible Polymers for AM Feedstock, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Cornerstone Research Group Inc. (CRG) proposes to design and develop thermally-reversible polymeric materials that will function as reprocessable thermosetting...

  14. Reverse microemulsion synthesis of nickel-cobalt hexacyanoferrate/reduced graphene oxide nanocomposites for high-performance supercapacitors and sodium ion batteries

    Science.gov (United States)

    Qiu, Xiaoming; Liu, Yongchang; Wang, Luning; Fan, Li-Zhen

    2018-03-01

    Prussian blue analogues with tunable open channels are of fundamental and technological importance for energy storage systems. Herein, a novel facile synthesis of nickel-cobalt hexacyanoferrate/reduced graphene oxide (denoted as Ni-CoHCF/rGO) nanocomposite is realized by a reverse microemulsion method. The very fine Ni-CoHCF nanoparticles (10-20 nm) are homogeneously anchored on the surface of reduced graphene oxide by electrostatic adsorption and reduced graphene oxide is well-separated by Ni-CoHCF particles. Benefiting from the combined advantages of this structure, the Ni-. It CoHCF/rGO nanocomposite can be used as electrodes for both supercapacitors and sodium ion batteries exhibits excellent pseudocapacitve performance in terms of high specific capacitance of 466 F g-1 at 0.2 A g-1 and 350 F g-1 at 10 A g-1, along with high cycling stabilities. As a cathode material for sodium ion batteries, it also demonstrates a high reversible capacity of 118 mAh g-1 at 0.1 A g-1, good rate capability, and superior cycling stability. These results suggest its potential as an efficient electrode for high-performance energy storage and renewable delivery devices.

  15. Design of a core–shell Pt–SiO2 catalyst in a reverse microemulsion system: Distinctive kinetics on CO oxidation at low temperature

    KAUST Repository

    Al Mana, Noor

    2016-06-28

    The mechanism of formation of Pt@SiO2 as a model of core–shell nanoparticles via water-in-oil reverse microemulsions was studied in detail. By controlling the time of growth of Pt precursors, Pt(OH)x, after hydrolysis in NH3 aq. before adding SiO2 precursor (TEOS), Pt nanoparticles with a narrow size distribution were produced, from ultrafine metal nanoparticles (<1 nm) to 6 nm nanocrystals. Separately, the thickness of SiO2 was controllably synthesized from 1 to 15 nm to yield different Pt@SiO2 materials. The Pt@SiO2 core–shell catalysts exhibited a higher rate of CO oxidation by one order of magnitude with a positive order regarding CO pressure. The SiO2 shell did not perturb the Pt chemical nature, but it provided different coverage of CO in steady-state CO oxidation. © 2016 Elsevier Inc.

  16. Microemulsions theory and practice

    CERN Document Server

    Prince, Leon

    1977-01-01

    Microemulsions: Theory and Practice covers the development of the theory and practice of microemulsion systems. This book is divided into seven chapters that explore the physics and chemistry of microemulsions. This book deals first with the commercial history of microemulsions, from the discovery of carnauba wax emulsions to polymer emulsions. This topic is followed by discussions on the theoretical aspects of microemulsion formulation techniques and the design of other products. The subsequent chapter describes the microemulsion formulation with less solubilizer or emulsifier together wi

  17. Reclaimable Thermally Reversible Polymers for AM Feedstock, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — CRG proposes to continue efforts from the 2016 NASA SBIR Phase I topic H5.04 Reclaimable Thermally Reversible Polymers for AM Feedstock. In Phase II, CRG will refine...

  18. Reversible thermal gelation in soft spheres

    DEFF Research Database (Denmark)

    Kapnistos, M.; Vlassopoulos, D.; Fytas, G.

    2000-01-01

    Upon heating, concentrated solutions of star polymers and block copolymer micelles in a good solvent, representing soft spheres, undergo a reversible gelation. This phenomenon is attributed to the formation of clusters causing a partial dynamic arrest of the swollen interpenetrating spheres at hi...

  19. Reversible thermal denaturation of immobilized rhodanese

    International Nuclear Information System (INIS)

    Horowitz, P.; Bowman, S.

    1987-01-01

    For the first time, the enzyme rhodanese had been refolded after thermal denaturation. This was previously not possible because of the strong tendency for the soluble enzyme to aggregate at temperatures above 37 degrees C. The present work used rhodanese that was covalently coupled to a solid support under conditions that were found to preserve enzyme activity. Rhodanese was immobilized using an N-hydroxymalonimidyl derivative of Sepharose containing a 6-carbon spacer. The number of immobilized competent active sites was measured by using [ 35 S]SO 3 (2-) to form an active site persulfide that is the obligatory catalytic intermediate. Soluble enzyme was irreversibly inactivated in 10 min at 52 degrees C. The immobilized enzyme regained at least 30% of its original activity even after boiling for 20 min. The immobilized enzyme had a Km and Vmax that were each approximately 3 times higher than the corresponding values for the native enzyme. After preincubation at high temperatures, progress curves for the immobilized enzyme showed induction periods of up to 5 min before attaining apparently linear steady states. The pH dependence of the activity was the same for both the soluble and the immobilized enzyme. These results indicate significant stabilization of rhodanese after immobilization, and instabilities caused by adventitious solution components are not the sole reasons for irreversibility of thermal denaturation seen with the soluble enzyme. The results are consistent with models for rhodanese that invoke protein association as a major cause of inactivation of the enzyme. Furthermore, the induction period in the progress curves is consistent with studies which show that rhodanese refolding proceeds through intermediate states

  20. Thermally activated magnetization reversal in magnetic tunnel junctions

    International Nuclear Information System (INIS)

    Guang-Hong, Zhou; Yin-Gang, Wang; Xian-Jin, Qi; Zi-Quan, Li; Jian-Kang, Chen

    2009-01-01

    In this paper, the magnetization reversal of the ferromagnetic layers in the IrMn/CoFe/AlO x /CoFe magnetic tunnel junction has been investigated using bulk magnetometry. The films exhibit very complex magnetization processes and reversal mechanism. Thermal activation phenomena such as the training effect, the asymmetry of reversal, the loop broadening and the decrease of exchange field while holding the film at negative saturation have been observed on the hysteresis loops of the pinned ferromagnetic layer while not on those of the free ferromagnetic layer. The thermal activation phenomena observed can be explained by the model of two energy barrier distributions with different time constants. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  1. Polymeric bicontinuous microemulsions

    DEFF Research Database (Denmark)

    Bates, F.S.; Maurer, W.W.; Lipic, P.M.

    1997-01-01

    High molecular weight block copolymers can be viewed as macromolecular surfactants when blended with thermodynamically incompatible homopolymers. This Letter describes the formation of polymeric bicontinuous microemulsions in nurtures containing a model diblock copolymer and two homopolymers. Alt...

  2. Introduction to Microemulsions

    Directory of Open Access Journals (Sweden)

    Gotić, M.

    2013-11-01

    Full Text Available Hoar and Schulman were the first (in 1943 to describe the transparent water-in-oil dispersion. They noted that a certain combination of water, oil, surfactant and alcohol cosurfactant would produce a clear homogeneous "solution", which Schulman in 1959 termed microemulsion. Schulman’s model of the inverse submicroscopic micelle is shown in Fig. 1. The IUPAC definitiondescribes microemulsion as a dispersion made of water, oil, and surfactant(s, which is an isotropic and thermodynamically stable system with dispersed domain diameter varying approximately from 1 to 100 nm, usually 10 to 50 nm. Water-in-oil microemulsions are important for the synthesis of various inorganic materials. In contrast to inverse micelle, water-in-oil micro-emulsion aggregates have mobile or free water in the core of the aggregate (Fig. 2. Reactions take place in a small volume of water inside a microdroplet, which results in improved properties of the products in terms of purity and particle size distribution. Microdroplet size can be controlled by suitable choice and mixing ratio of surfactant and cosurfactant (Fig. 3 and by the chemical composition of the oil and water phases. Microemulsions may have complex phase behaviour, commonly displayed in a phase diagram (Fig. 5 and Fig. 12. Surfactants are amphiphile molecules with hydrophilic head and lypophilic tail, thus bringing them affinity both to water and oil. Their main characteristics are adsorption at the interface and self-organization into supramolecular structures. By forming the interface layer, surfactants decrease surface tension and stabilize the microemulsion. According to the character of the hydrophilic head, surfactants are divided into anionic, cationic, nonionic, and amphoteric. Chemical structures of typical representatives are given in Fig. 6. Microemulsion aggregates may have various shapes, e.g. spherical, ellipsoidal, cylindrical, worm-like or bilayer (Fig. 7. Bicontinuous phase also occurs in

  3. SMA bellows as reversible thermal sensors/actuators

    International Nuclear Information System (INIS)

    Damanpack, A R; Bodaghi, M; Liao, W H

    2015-01-01

    In this paper, the feasibility of reversible bellows made of shape memory alloys (SMAs) in sensory and actuated applications to transfer pressure and/or temperature into a linear motion is investigated. An analytical three-dimensional model is developed to simulate key features of SMAs including martensitic transformation, reorientation of martensite variants, the shape memory effect, and pseudo-elasticity. Axisymmetric two-dimensional theory of thermo-inelasticity based on the non-linear Green–Lagrange strain tensor is employed to derive the equilibrium equations. A finite element method along with an iterative incremental elastic-predictor–inelastic-corrector procedure is developed to solve the governing equations with both material and geometrical non-linearities. The feasibility of reversible SMA bellows in transferring pressure and/or temperature into a linear motion is numerically demonstrated. In this respect, the effects of geometric parameters, magnitude of thermo-mechanical loadings and end conditions on the performances of SMA bellows are evaluated and discussed in depth. This study provides pertinent results toward an efficient and reliable design of reversible thermally-driven SMA bellows. (paper)

  4. Microemulsion Synthesis of Nanoparticles

    Directory of Open Access Journals (Sweden)

    Gotić, M.

    2013-11-01

    Full Text Available Nanoparticles and nanomaterials have wide applications in electronics, physics, material design, being also utilized as sensors, catalysts, and more and more in biomedicine. Microemulsions are an exceptionally suitable medium for the synthesis of nanoparticles due to their thermodynamical stability, great solubility of both polar and nonpolar components, as well as their ability to control the size, dispersity and shape of the particles. This review presents microemulsion techniques for the synthesis of inorganic nanoparticles. It takes place in water-in-oil microemulsions by mixing one microemulsion with a cationic precursor, and the other with a precipitating or reducing agent, or by direct addition of reducing agents or gas (O2, NH3 ili CO2 into microemul sion (Fig. 1. Metal nanoparticles are used as catalysts, sensors, ferrofluids etc. They are produced by reducing the metal cation with a suitable reducing agent. In a similar way, one can prepare nanoparticles of alloys from the metal salts, provided that the metals are mutually soluble. The microemulsion technique is also suitable for depositing nanoparticles onto various surfaces. Highly active catalysts made from nanoparticles of Pt, Pd, Rh and other noble metals may be obtained in this way. Metal oxides and hydroxides may be prepared by hydrolysis or precipitation in the water core of microemulsion. Precipitation can be initiated by adding the base or precipitating agent into the microemulsion with water solution of metal ions. Similarly, nanoparticles may be prepared of sulphides, halogenides, cyanides, carbonates, sulphates and other insoluble metal salts. To prevent oxidation of nanoparticles, especially Fe, the particles are coated with inert metals, oxides, various polymers etc. Coating may provide additional functionality; e.g. coating with gold allows subsequent functionalization with organic compounds containing sulphur, due to the strong Au–S bond. Polymer coatings decrease

  5. Thermally reversible cross-linked poly(ether-urethanes

    Directory of Open Access Journals (Sweden)

    V. Gaina

    2013-07-01

    Full Text Available Cross-linked poly(ether-urethanes were prepared by Diels-Alder (DA reaction of the furan-containing poly(ether-urethane to bismaleimides and showed thermal reversibility evidenced by differential scanning calorimetry and attenuated total reflectance in conjunction with Fourier transform infrared spectroscopy (ATR-FTIR. The furan-containing poly(ether-urethanes were synthesized by the polyaddition reaction of 1,6-hexamethylene diisocyanate (HMDI or 4,4'- dibenzyl diisocyanate (DBDI to poly(tetramethylene ether glycol (PTMEG having Mn = 250, 650, 1000, 1500 and 2000 and 2-[N,N-bis(2-methyl-2-hydroxyethylamino]furfuryl as chain extender by the solution prepolymer method. The molar ratio of isocyanate: PTMEG:chain extender varied from 2:1:1 to 4:1:3, which produces a molar concentration of furyl group ranging between 3.65•10–4 and 1.25•10–3 mol/g.

  6. Adjustable thermal resistor by reversibly folding a graphene sheet.

    Science.gov (United States)

    Song, Qichen; An, Meng; Chen, Xiandong; Peng, Zhan; Zang, Jianfeng; Yang, Nuo

    2016-08-11

    Phononic (thermal) devices such as thermal diodes, thermal transistors, thermal logic gates, and thermal memories have been studied intensively. However, tunable thermal resistors have not been demonstrated yet. Here, we propose an instantaneously adjustable thermal resistor based on folded graphene. Through theoretical analysis and molecular dynamics simulations, we study the phonon-folding scattering effect and the dependence of thermal resistivity on the length between two folds and the overall length. Furthermore, we discuss the possibility of realizing instantaneously adjustable thermal resistors in experiment. Our studies bring new insights into designing thermal resistors and understanding the thermal modulation of 2D materials by adjusting basic structure parameters.

  7. Microemulsion Electrokinetic Chromatography.

    Science.gov (United States)

    Buchberger, Wolfgang

    2016-01-01

    Microemulsion electrokinetic chromatography (MEEKC) is a special mode of capillary electrophoresis employing a microemulsion as carrier electrolyte. Analytes may partition between the aqueous phase of the microemulsion and its oil droplets which act as a pseudostationary phase. The technique is well suited for the separation of neutral species, in which case charged oil droplets (obtained by addition of an anionic or cationic surfactant) are present. A single set of separation parameters may be sufficient for separation of a wide range of analytes belonging to quite different chemical classes. Fine-tuning of resolution and analysis time may be achieved by addition of organic solvents, by changes in the nature of the surfactants (and cosurfactants) used to stabilize the microemulsion, or by various additives that may undergo some additional interactions with the analytes. Besides the separation of neutral analytes (which may be the most important application area of MEEKC), it can also be employed for cationic and/or anionic species. In this chapter, MEEKC conditions are summarized that have proven their reliability for routine analysis. Furthermore, the mechanisms encountered in MEEKC allow an efficient on-capillary preconcentration of analytes, so that the problem of poor concentration sensitivity of ultraviolet absorbance detection is circumvented.

  8. Microstructure characterization of a food-grade U-type microemulsion system by differential scanning calorimetry and electrical conductivity techniques.

    Science.gov (United States)

    Zhang, Hui; Taxipalati, Maierhaba; Que, Fei; Feng, Fengqin

    2013-12-01

    The microstructure transitions of a food-grade U-type microemulsion system containing glycerol monolaurate and propionic acid at a 1:1 mass ratio as oil phase and Tween 80 as surfactant were investigated along a water dilution line at a ratio of 80:20 mass% surfactant/oil phase, based on a previously studied phase diagram. From the water thermal behaviours detected by differential scanning calorimetry, three structural regions are identified along the dilution line. In the first region, all water molecules are confined to the water core of the reverse micelles, leading to the formation of w/o microemulsion. As the water content increases, the water gains mobility, transforms into bicontinuous in the second region, and finally the microemulsion become o/w in the third region. The thermal transition points coincide with the structural phase transitions by electrical conductivity measurements, indicating that the structural transitions occur at 35 and 65 mass% of water along the dilution line. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Chemical and Photochemical Reactivity in Microemulsions and Waterless Microemulsions.

    Science.gov (United States)

    1988-02-10

    virtually the same as that found in the alcohol rich microemulsion A. This value is also close to that found in pure butanol (= 5.0 - table I). It would...formamide or alcohol rich). RESEARCH PATTERN -Supplementing the physical chemical study of the microemulsion medium involving ionic surfactants with density...SAMII (1/02/1988) Ii&N 3 Part II - OXYDATIONS BY HYDROPEROXIDES IN MICROEMULSIONS E. OLIVEROS and M.T. MAURETTE During the past six months, the financial

  10. Preparation of Silver Nanostructures from Bicontinuous Microemulsions

    Directory of Open Access Journals (Sweden)

    M. A. Pedroza-Toscano

    2012-01-01

    Full Text Available Precipitation of silver nanoparticles at 70°C was carried out by dosing a 1.3 M sodium borohydride aqueous solution over bicontinuous microemulsions formed with a mixture of sodium bis(2-ethylhexyl sulfosuccinate (AOT and sodium dodecylsulfate (SDS as surfactants, a 0.5 M silver nitrate aqueous solution, and toluene. Weight ratios of 2.5/1 and 3/1 AOT/SDS were used in the precipitation reactions. Silver nanoparticles were characterized by transmission electronic microscopy, X-ray diffraction, and atomic absorption spectroscopy. A mixture of isolated spheroidal nanoparticles (≈15 wt.% with an average diameter around 10 nm and wormlike structures (≈85 wt.% with an average length close to 480 nm and an average diameter ca. 40 nm was obtained, regardless of the AOT/SDS ratio. Higher yields were obtained compared with those reported when reverse microemulsions were employed. Formation of wormlike structures was ascribed to one-dimensional aggregation of crystal and particles within the channels of bicontinuous microemulsions, which performed as templates.

  11. Microemulsion prepared Ni88Pt12 for methane cracking

    KAUST Repository

    Zhou, Lu

    2017-01-16

    Monodispersed NiPt nanoparticles of 10 nm were synthesized by water-in-oil microemulsion. The Ni-Pt alloy structure was stable during the thermal treatment between 330 and 1037 °C, whereas the relatively low temperature range of 600-700 °C was favorable for methane cracking to produce hydrogen and carbon nanotubes.

  12. Microemulsion prepared Ni88Pt12 for methane cracking

    KAUST Repository

    Zhou, Lu; Harb, Moussab; Hedhili, Mohamed N.; Mana, Noor Al; Basset, Jean-Marie

    2017-01-01

    Monodispersed NiPt nanoparticles of 10 nm were synthesized by water-in-oil microemulsion. The Ni-Pt alloy structure was stable during the thermal treatment between 330 and 1037 °C, whereas the relatively low temperature range of 600-700 °C was favorable for methane cracking to produce hydrogen and carbon nanotubes.

  13. Polarizability of Fluid Droplets and the Kerr Effect on Microemulsions

    CERN Document Server

    Lisy, V

    2001-01-01

    Spheroidal fluid droplets immersed in another fluid and thermally fluctuating in the shape are considered. The polarizability of the droplet is evaluated up to the second order in the fluctuation amplitudes. The correlation functions of the polarizability tensor components are found and used to describe the polarized and depolarized scattering of light, and the Kerr effect on microemulsions. By comparison of the theoretical results with the Kerr constant measurements from the literature, we estimate the bending rigidity of the surfactant monolayer that separates the oil and water phases in droplet microemulsions.

  14. Precipitation of Zinc Oxide Nanoparticles in Bicontinuous Microemulsions

    Directory of Open Access Journals (Sweden)

    Liliana E. Romo

    2011-01-01

    Full Text Available Zinc oxide nanoparticles were obtained directly, avoiding the calcination step, by precipitation at 70°C in bicontinuous microemulsions stabilized with a mixture of surfactants sodium bis (2-ethylhexyl sulfosuccinate/sodium dodecyl sulfate (2/1, wt./wt. containing 0.7 M zinc nitrate aqueous solution. Two concentrations of aqueous solution of precipitating agent sodium hydroxide were used under different dosing times on microemulsion. Characterization by X-ray diffraction and electron microscopy allowed us to identify particles with an acicular rod-like morphology and a hexagonal wurtzite crystal structure as small as 8.5 and 30 nm in average diameter and length, respectively. Productivities much higher than those typical in the preparation of zinc oxide nanoparticles via reverse microemulsions were obtained. Particle size was the same at the two studied sodium hydroxide concentrations, while it increases as dosing time of the precipitant agent increases. It is believed that the surfactant film on the microemulsion channels restricts the particle diameter growth.

  15. Reversible temperature regulation of electrical and thermal conductivity using liquid–solid phase transitions

    Science.gov (United States)

    Zheng, Ruiting; Gao, Jinwei; Wang, Jianjian; Chen, Gang

    2011-01-01

    Reversible temperature tuning of electrical and thermal conductivities of materials is of interest for many applications, including seasonal regulation of building temperature, thermal storage and sensors. Here we introduce a general strategy to achieve large contrasts in electrical and thermal conductivities using first-order phase transitions in percolated composite materials. Internal stress generated during a phase transition modulates the electrical and thermal contact resistances, leading to large contrasts in the electrical and thermal conductivities at the phase transition temperature. With graphite/hexadecane suspensions, the electrical conductivity changes 2 orders of magnitude and the thermal conductivity varies up to 3.2 times near 18 °C. The generality of the approach is also demonstrated in other materials such as graphite/water and carbon nanotube/hexadecane suspensions. PMID:21505445

  16. Reversible temperature regulation of electrical and thermal conductivity using liquid-solid phase transitions.

    Science.gov (United States)

    Zheng, Ruiting; Gao, Jinwei; Wang, Jianjian; Chen, Gang

    2011-01-01

    Reversible temperature tuning of electrical and thermal conductivities of materials is of interest for many applications, including seasonal regulation of building temperature, thermal storage and sensors. Here we introduce a general strategy to achieve large contrasts in electrical and thermal conductivities using first-order phase transitions in percolated composite materials. Internal stress generated during a phase transition modulates the electrical and thermal contact resistances, leading to large contrasts in the electrical and thermal conductivities at the phase transition temperature. With graphite/hexadecane suspensions, the electrical conductivity changes 2 orders of magnitude and the thermal conductivity varies up to 3.2 times near 18 °C. The generality of the approach is also demonstrated in other materials such as graphite/water and carbon nanotube/hexadecane suspensions.

  17. Cessations and reversals of the large-scale circulation in turbulent thermal convection.

    Science.gov (United States)

    Xi, Heng-Dong; Xia, Ke-Qing

    2007-06-01

    We present an experimental study of cessations and reversals of the large-scale circulation (LSC) in turbulent thermal convection in a cylindrical cell of aspect ratio (Gamma) 1/2 . It is found that cessations and reversals of the LSC occur in Gamma = 1/2 geometry an order-of-magnitude more frequently than they do in Gamma=1 cells, and that after a cessation the LSC is most likely to restart in the opposite direction, i.e., reversals of the LSC are the most probable cessation events. This contrasts sharply to the finding in Gamma=1 geometry and implies that cessations in the two geometries are governed by different dynamics. It is found that the occurrence of reversals is a Poisson process and that a stronger rebound of the flow strength after a reversal or cessation leads to a longer period of stability of the LSC. Several properties of reversals and cessations in this system are found to be statistically similar to those of geomagnetic reversals. A direct measurement of the velocity field reveals that a cessation corresponds to a momentary decoherence of the LSC.

  18. Damping Dependence of Reversal Magnetic Field on Co-based Nano-Ferromagnetic with Thermal Activation

    Directory of Open Access Journals (Sweden)

    Nadia Ananda Herianto

    2015-02-01

    Full Text Available Currently, hard disk development has used HAMR technology that applies heat to perpendicular media until near Curie temperature, then cools it down to room temperature. The use of HAMR technology is significantly influence by Gilbert damping constants. Damping affects the magnetization reversal and coercivity field. Simulation is used to evaluate magnetization reversal by completing Landau-Lifshitz-Gilbert explicit equation. A strong ferromagnetic cobalt based material with size 50×50×20 nm3 is used which parameters are anisotropy materials 3.51×106 erg/cm3, magnetic saturation 5697.5 G, exchange constant 1×10-7 erg/cm, and various Gilbert damping from 0.09 to 0.5. To observe the thermal effect, two schemes are used which are Reduced Barrier Writing and Curie Point Writing. As a result, materials with high damping is able to reverse the magnetizations faster and reduce the energy barrier. Moreover, it can lower the minimum field to start the magnetizations reversal, threshold field, and probability rate. The heating near Curie temperature has succeeded in reducing the reversal field to 1/10 compared to writing process in absence of thermal field.

  19. "Phase diagrams of Lecithin-based microemulsions containing Sodium Salicylate "

    Directory of Open Access Journals (Sweden)

    "Aboofazeli R

    2000-08-01

    Full Text Available Partial phase diagrams were constructed at 25°C to investigate the phase behaviour of systems composed of soybean lecithin, water, sodium salicylate, alcohol and isopropyl myristate. The lecithins used were the commercially available soy bean lecithins, namely E200 and E170 (phosphatidyl choline purities greater than 95% and 68-72% respectively. The cosurfactants employed were n-propanol, 2-propanol and n-butanol and these were used at lecithin/alcohol weight ratios (Km of 1:1 and 1.5:1. At a given Km, the aqueous phase consisted of a 2% w/w sodium salicylate solution. Phase diagrams showed the area of existence of a stable isotropic region along the surfactant/oil axis (i.e., reverse microemulsion area. The extension of the microemulsion domain was influenced by the purity of surfactant, the lecithin/alcohol weight ratios and the kind of the alcohol.

  20. Selectivity in microemulsion electrokinetic chromatography

    DEFF Research Database (Denmark)

    Pedersen-Bjergaard, S; Gabel-Jensen, Charlotte; Honoré Hansen, S

    2000-01-01

    Microemulsion electrokinetic chromatography (MEEKC) is a most promising separation technique providing good selectivity and high separation efficiency of anionic, cationic as well as neutral solutes. In MEEKC lipophilic organic solvents dispersed as tiny droplets in an aqueous buffer by the use...

  1. Effects of Anisotropic Thermal Conductivity in Magnetohydrodynamics Simulations of a Reversed-Field Pinch

    International Nuclear Information System (INIS)

    Onofri, M.; Malara, F.; Veltri, P.

    2010-01-01

    A compressible magnetohydrodynamics simulation of the reversed-field pinch is performed including anisotropic thermal conductivity. When the thermal conductivity is much larger in the direction parallel to the magnetic field than in the perpendicular direction, magnetic field lines become isothermal. As a consequence, as long as magnetic surfaces exist, a temperature distribution is observed displaying a hotter confined region, while an almost uniform temperature is produced when the magnetic field lines become chaotic. To include this effect in the numerical simulation, we use a multiple-time-scale analysis, which allows us to reproduce the effect of a large parallel thermal conductivity. The resulting temperature distribution is related to the existence of closed magnetic surfaces, as observed in experiments. The magnetic field is also affected by the presence of an anisotropic thermal conductivity.

  2. Promising and Reversible Electrolyte with Thermal Switching Behavior for Safer Electrochemical Storage Devices.

    Science.gov (United States)

    Shi, Yunhui; Zhang, Qian; Zhang, Yan; Jia, Limin; Xu, Xinhua

    2018-02-28

    A major stumbling block in large-scale adoption of high-energy-density electrochemical devices has been safety issues. Methods to control thermal runaway are limited by providing a one-time thermal protection. Herein, we developed a simple and reversible thermoresponsive electrolyte system that is efficient to shutdown the current flow according to temperature changes. The thermal management is ascribed to the thermally activated sol-gel transition of methyl cellulose solution, associated with the concentration of ions that can move between isolated chains freely or be restricted by entangled molecular chains. We studied the effect of cellulose concentration, substituent types, and operating temperature on the electrochemical performance, demonstrating an obvious capacity loss up to 90% approximately of its initial value. Moreover, this is a cost-effective approach that has the potential for use in practical electrochemical storage devices.

  3. Thermal Cycling and High Temperature Reverse Bias Testing of Control and Irradiated Gallium Nitride Power Transistors

    Science.gov (United States)

    Patterson, Richard L.; Boomer, Kristen T.; Scheick, Leif; Lauenstein, Jean-Marie; Casey, Megan; Hammoud, Ahmad

    2014-01-01

    The power systems for use in NASA space missions must work reliably under harsh conditions including radiation, thermal cycling, and exposure to extreme temperatures. Gallium nitride semiconductors show great promise, but information pertaining to their performance is scarce. Gallium nitride N-channel enhancement-mode field effect transistors made by EPC Corporation in a 2nd generation of manufacturing were exposed to radiation followed by long-term thermal cycling and testing under high temperature reverse bias conditions in order to address their reliability for use in space missions. Result of the experimental work are presented and discussed.

  4. Study of surfactant-free microemulsions and microemulsions with fatty acid salts

    OpenAIRE

    Marcus, Julien

    2016-01-01

    This thesis deals with the study of microemulsions and is composed of two main parts. In the first part, surfactant-free microemulsions are studied, whereas in the second part microemulsions with surfactants and cosurfactants are investigated. Over the last few years, surfactant-free microemulsions became a major topic at our institute and were thoroughly studied using the reference system water/ethanol/1-octanol. As explained later in the Fundamentals part (see section 1.2), fluctuating ...

  5. A functionalizable reverse thermal gel based on a polyurethane/PEG block copolymer

    Science.gov (United States)

    Park, Daewon; Wu, Wei; Wang, Yadong

    2010-01-01

    Injectable reverse thermal gels have great potentials as biomaterials for tissue engineering and drug delivery. However, most existing gels lack functional groups that can be modified with biomolecules that can guide cell/material interactions. We created an amine-functionalized ABA block copolymer, poly(ethylene glycol)-poly(serinol hexamethylene urethane), or ESHU. This reverse thermal gel consists of a hydrophobic block (B): poly(serinol hexamethylene urethane) and a hydrophilic block (A): poly(ethylene glycol). The polymer was characterized by GPC, FTIR and 1H FTNMR. Rheological study demonstrated that ESHU solution in phosphate-buffered saline initiated phase transition at 32°C and reached maximum elastic modulus at 37°C. The in vitro degradation tests performed in PBS and cholesterol esterase solutions revealed that the polymer was hydrolyzable and the presence of cholesterol esterase greatly accelerated the hydrolysis. The in vitro cytotoxicity tests carried out using baboon smooth muscle cells demonstrated that ESHU had good cytocompatibility with cell viability indistinguishable from tissue culture treated polystyrene. Subcutaneous implantation in rats revealed well tolerated accurate inflammatory response with moderate ED-1 positive macrophages in the early stages, which largely resolved 4 weeks post-implantation. We functionalized ESHU with a hexapeptide, Ile-Lys-Val-Ala-Val-Ser (IKVAVS), which gelled rapidly at body temperature. We expect this new platform of functionalizable reverse thermal gels to provide versatile biomaterials in tissue engineering and regenerative medicine. PMID:20937526

  6. Pressure-induced reversal between thermal contraction and expansion in ferroelectric PbTiO3.

    Science.gov (United States)

    Zhu, Jinlong; Zhang, Jianzhong; Xu, Hongwu; Vogel, Sven C; Jin, Changqing; Frantti, Johannes; Zhao, Yusheng

    2014-01-15

    Materials with zero/near zero thermal expansion coefficients are technologically important for applications in thermal management and engineering. To date, this class of materials can only be produced by chemical routes, either by changing chemical compositions or by composting materials with positive and negative thermal expansion. Here, we report for the first time a physical route to achieve near zero thermal expansion through application of pressure. In the stability field of tetragonal PbTiO3 we observed pressure-induced reversals between thermal contraction and expansion between ambient pressure and 0.9 GPa. This hybrid behavior leads to a mathematically infinite number of crossover points in the pressure-volume-temperature space and near-zero thermal expansion coefficients comparable to or even smaller than those attained by chemical routes. The observed pressures for this unusual phenomenon are within a small range of 0.1-0.9 GPa, potentially feasible for designing stress-engineered materials, such as thin films and nano-crystals, for thermal management applications.

  7. Like night and day: Reversals of thermal gradients across ghost crab burrows and their implications for thermal ecology

    Science.gov (United States)

    Watson, Gregory S.; Gregory, Emily A.; Johnstone, Charmaine; Berlino, Manuel; Green, David W.; Peterson, Nicola R.; Schoeman, David S.; Watson, Jolanta A.

    2018-04-01

    Ghost crabs, Ocypode cordimanus, inhabit relatively hostile environments subject to thermal fluctuations, including both diurnal and seasonal cycles. For many ectotherms, including ghost crabs, a major challenge is to remain cool during hot daytime temperatures. This can be achieved by adopting a fossorial lifestyle, taking advantage of thermal refuge afforded by burrows of sufficient depth. Another consideration, often overlooked, is the potential advantage associated with ready access to a thermal energy source (a "charging station") when surface temperatures are cooler. Being able to rapidly elevate body temperature during cool periods would enhance the crab's ability to maintain rate processes and carry out essential activities. We have measured ghost crab burrow temperature profiles at two times of the day with contrasting sun exposure (06:00 and 14:00), demonstrating how effective burrow depth (up to a maximum of 40 cm) provides thermal regulation below the surface of the sand (e.g., at dawn (06:00) and early afternoon (14:00) at a depth of 5 cm, temperatures (±SD) of 16.32 ± 0.96 °C and 25.04 ± 1.47 °C were recorded, respectively. Corresponding temperatures at a depth of 30 cm were 19.17 ± 0.59 °C and 19.78 ± 1.60 °C, respectively). This demonstrates that while temperature conditions at the surface vary dramatically from night to day, ghost crab burrows can maintain relatively constant temperatures at the burrow base throughout the diurnal cycle, at least during winter. As a consequence, the burrow heat signatures undergo a corresponding thermal gradient reversal between night and day, as revealed by infra-red photography. Complementing these field observations, we also determined heating and cooling times/constants for O. cordimanus in the laboratory (τ = 17.54 and 16.59 JK-1, respectively), and analysed chemical composition of their carapace (external (with β Chitin evident) and internal (predominance of α Chitin)), which is the primary thermal

  8. Microemulsion based approach for nanospheres assembly into anisotropic nanostructures of NiMnO3 and their magnetic properties

    Science.gov (United States)

    Jha, Menaka; Kumar, Sandeep; Garg, Neha; Ramanujachary, Kandalam V.; Lofland, Samuel E.; Ganguli, Ashok K.

    2018-02-01

    The present study focuses on synthesis of anisotropic nanostructures of nickel manganese oxide (NiMnO3) obtained by thermal decomposition of nanocrystalline nickel manganese oxalate precursor, Ni0.5Mn0.5(C2O4)·2H2O which crystallized as nanorods. The synthesis of the oxalate precursor has been carried out via microemulsion-mediated process with cationic and non-ionic surfactants. The microemulsion led to reverse micelles, and the film flexibility of the micelle in presence of non-ionic surfactant (Tergitol) was reduced by increasing the chain length of the co-surfactant (1-butanol, 1-hexanol and 1-octanol) which led to the increase in reaction rate and hence increase in the aspect ratio of the nickel manganese oxalate by up to four times. However, in the presence of cationic surfactant, highly uniform nickel manganese oxalate nanorods were obtained. Further, the decomposition of the oxalate precursor was optimized to maintain the anisotropy of the rods of ternary metal oxide (NiMnO3). An electron microscopy study showed that the rods were made up of an assembly of ultrafine nanospheres. The NiMnO3 nanostructures were all ferrimagnetic with Curie temperature ranging between 437 and 467 K showing increasing saturation magnetization with increase in aspect ratio of the nanorods.

  9. Adapalene microemulsion for transfollicular drug delivery.

    Science.gov (United States)

    Bhatia, Gaurav; Zhou, Yingcong; Banga, Ajay K

    2013-08-01

    The aim of this study was to develop a microemulsion formulation of adapalene for transfollicular delivery. A pseudoternary phase diagram was developed for microemulsion consisting of oleic acid as oil phase, tween 20 as surfactant, Transcutol® as cosurfactant, and deionized water. Differential tape stripping and confocal laser scanning microscopy were performed to determine the penetration of microemulsion through hair follicles. Transmission electron microscopy, dynamic light scattering, polarizing light microscopy, and differential scanning calorimetry were performed to characterize the microstructures of microemulsion. The pH and viscosity of the microemulsions were also determined. Permeation studies were carried out in vitro on porcine ear skin over a period of 24 h using Franz diffusion cells. The drug penetration in the hair follicles increased from 0.109 ± 0.03 to 0.292 ± 0.094 μg, as the microstructure of microemulsion shifted from oil-in-water to bi-continuous, with increase in water content of microemulsion. Confocal laser scanning microscopy images suggested that hair follicles provided the path for transfollicular permeation of adapalene microemulsion. These results suggest that microemulsion penetrated through hair follicles and are promising for transfollicular drug delivery. Copyright © 2013 Wiley Periodicals, Inc.

  10. Microemulsion Drug Delivery Systems for Radiopharmacy Studies

    Directory of Open Access Journals (Sweden)

    Emre Ozgenc

    2016-11-01

    Full Text Available Microemulsions have been used increasingly for last year’s because of ideal properties like favorable drug delivery, ease of preparation and physical stability. They have been improved the solubility and efficacy of the drug and reduce the side effects. Use of radiolabeled microemulsions plays an alternative role in drug delivery systems by investigating the formation, stability and application of microemulsions in radiopharmacy. Gama scintigraphic method is well recognized for developing and detecting the biodistribution of newly developed drugs or formulation. This review will focus on how radionuclides are able to play role with characterization studies of microemulsion drug delivery systems.

  11. Microemulsions based transdermal drug delivery systems.

    Science.gov (United States)

    Vadlamudi, Harini C; Narendran, Hyndavi; Nagaswaram, Tejeswari; Yaga, Gowri; Thanniru, Jyotsna; Yalavarthi, Prasanna R

    2014-01-01

    Since the discovery of microemulsions by Jack H Schulman, there has been huge progress made in applying microemulsion systems in plethora of research and industrial process. Microemulsions are optically isotropic systems consisting of water, oil and amphiphile. These systems are beneficial due to their thermodynamic stability, optical clarity, ease of preparation, higher diffusion and absorption rates. Moreover, it has been reported that the ingredients of microemulsion can effectively overcome the diffusion barrier and penetrate through the stratum corneum of the skin. Hence it becomes promising for both transdermal and dermal drug delivery. However, low viscosity of microemulsion restrains its applicability in pharmaceutical industry. To overcome the above drawback, the low viscous microemulsions were added to viscous gel bases to potentiate its applications as topical drug delivery systems so that various drug related toxic effects and erratic drug absorption can be avoided. The present review deals with the microemulsions, various techniques involved in the development of organic nanoparticles. The review emphasized on microemulsion based systems such as hydrogels and organogels. The physicochemical characteristics, mechanical properties, rheological and stability principles involved in microemulsion based viscous gels were also explored.

  12. Open loop, auto reversing liquid nitrogen circulation thermal system for thermo vacuum chamber

    International Nuclear Information System (INIS)

    Naidu, M C A; Nolakha, Dinesh; Saharkar, B S; Kavani, K M; Patel, D R

    2012-01-01

    In a thermo vacuum chamber, attaining and controlling low and high temperatures (-100 Deg. C to +120 Deg. C) is a very important task. This paper describes the development of 'Open loop, auto reversing liquid nitrogen based thermal system'. System specifications, features, open loop auto reversing system, liquid nitrogen flow paths etc. are discussed in this paper. This thermal system consists of solenoid operated cryogenic valves, double embossed thermal plate (shroud), heating elements, temperature sensors and PLC. Bulky items like blowers, heating chambers, liquid nitrogen injection chambers, huge pipe lines and valves were not used. This entire thermal system is very simple to operate and PLC based, fully auto system with auto tuned to given set temperatures. This system requires a very nominal amount of liquid nitrogen (approx. 80 liters / hour) while conducting thermo vacuum tests. This system was integrated to 1.2m dia thermo vacuum chamber, as a part of its augmentation, to conduct extreme temperature cycling tests on passive antenna reflectors of satellites.

  13. Role of anisotropic thermal conductivity in the reversed-field pinch dynamics

    International Nuclear Information System (INIS)

    Onofri, M.; Malara, F.; Veltri, P.

    2011-01-01

    Two compressible magnetohydrodynamics simulations of the reversed-field pinch are performed, with isotropic and anisotropic thermal conductivity. We describe in detail the numerical method we use to reproduce the effect of a large parallel thermal conductivity, which makes magnetic field lines almost isothermal. We compare the results of the two simulations, showing that the anisotropic thermal conductivity causes the formation of a hot island when closed magnetic surfaces exist, while temperature becomes almost uniform when the magnetic field is chaotic. After a transient single-helicity state that is formed in the initial phase, a stationary state is reached where the RFP configuration exists in a multiple helicity state, even though the Hartmann number is below the threshold found in previous simulations for the formation of multiple helicity states.

  14. Reversibility and two state behaviour in the thermal unfolding of oligomeric TIM barrel proteins.

    Science.gov (United States)

    Romero-Romero, Sergio; Costas, Miguel; Rodríguez-Romero, Adela; Alejandro Fernández-Velasco, D

    2015-08-28

    Temperature is one of the main variables that modulate protein function and stability. Thermodynamic studies of oligomeric proteins, the dominant protein natural form, have been often hampered because irreversible aggregation and/or slow reactions are common. There are no reports on the reversible equilibrium thermal unfolding of proteins composed of (β/α)8 barrel subunits, albeit this "TIM barrel" topology is one of the most abundant and versatile in nature. We studied the eponymous TIM barrel, triosephosphate isomerase (TIM), belonging to five species of different bacterial taxa. All of them were found to be catalytically efficient dimers. The three-dimensional structure of four enzymes was solved at high/medium resolution. Irreversibility and kinetic control were observed in the thermal unfolding of two TIMs, while for the other three the thermal unfolding was found to follow a two-state equilibrium reversible process. Shifts in the global stability curves of these three proteins are related to the organismal temperature range of optimal growth and modulated by variations in maximum stability temperature and in the enthalpy change at that temperature. Reversibility appears to correlate with the low isoelectric point, the absence of a residual structure in the unfolded state, small cavity volume in the native state, low conformational stability and a low melting temperature. Furthermore, the strong coupling between dimer dissociation and monomer unfolding may reduce aggregation and favour reversibility. It is therefore very thought-provoking to find that a common topological ensemble, such as the TIM barrel, can unfold/refold in the Anfinsen way, i.e. without the help of the cellular machinery.

  15. Preparation of silver nanocrystals in microemulsion by the γ-radiation method

    International Nuclear Information System (INIS)

    Hongkai Wu; Xiangling Xu; Xuewu Ge; Zhicheng Zhang

    1997-01-01

    Silver colloids of well-defined shape, size were synthesized by γ-ray irradiating silver salt in reversed microemulsions, and then pure silver dry powders were obtained. The sols were studied by absorption spectroscopy, and the silver powders were characterized by Transmission Electron Micrographs (TEM) and X-ray Diffraction (XRD). The effect of radiation dose and aging time was discussed. (Author)

  16. Micro-scale displacement of NAPL by surfactant and microemulsion in heterogeneous porous media

    Science.gov (United States)

    Javanbakht, Gina; Arshadi, Maziar; Qin, Tianzhu; Goual, Lamia

    2017-07-01

    Industrial processes such as remediation of oil-contaminated aquifers and enhanced oil recovery (EOR) often utilize chemical additives to increase the removal of non-aqueous phase liquids (NAPLs) from subsurface formations. Although the majority of crude oils are classified as LNAPLs, they often contain heavy molecules (DNAPLs) such as asphaltenes that tend to adsorb on minerals and alter their wettability. Effective additives are therefore those that can reduce the threshold capillary pressure, thus mobilizing LNAPL inside pore spaces and solubilizing DNAPL from rock surfaces. Nonionic surfactants in brine have often been injected to oil or contaminated aquifer formations in order to enhance NAPL displacement through IFT reduction. Recent studies revealed that surfactant-based microemulsions have a higher tendency to alter the wettability of surfaces, compared to surfactants alone, leading to more effective NAPL removal. However, the impact of these additives on pore-scale displacement mechanisms and multi-phase fluid occupancy in porous media is, to date, still unclear. In this study, x-ray microtomography experiments were performed to investigate the impact of surfactants and microemulsions on the mobilization and solubilization of NAPL in heterogeneous rocks. Saturation profiles indicated that an incremental NAPL removal was attained by addition of microemulsion to brine, compared with surfactant. Residual cluster size distributions revealed that microemulsions could break up large clusters into smaller disconnected ones, improving their mobilization in the rock. In-situ contact angle measurements showed that microemulsions could reverse the wettability of rough contaminated surfaces to a higher extent than surfactants. Unlike surfactant alone, the surfactant-solvent blend in the carrier fluid of microemulsions was able to penetrate rough grain surfaces, particularly those of dolomite cement, and desorb asphaltenes in the form of small-emulsified NAPL droplets

  17. Stochastic simulation of thermally assisted magnetization reversal in sub-100 nm dots with perpendicular anisotropy

    International Nuclear Information System (INIS)

    Purnama, Budi; Koga, Masashi; Nozaki, Yukio; Matsuyama, Kimihide

    2009-01-01

    Thermally assisted magnetization reversal of sub-100 nm dots with perpendicular anisotropy has been investigated using a micromagnetic Langevin model. The performance of the two different reversal modes of (i) a reduced barrier writing scheme and (ii) a Curie point writing scheme are compared. For the reduced barrier writing scheme, the switching field H swt decreases with an increase in writing temperature but is still larger than that of the Curie point writing scheme. For the Curie point writing scheme, the required threshold field H th , evaluated from 50 simulation results, saturates at a value, which is not simply related to the energy barrier height. The value of H th increases with a decrease in cooling time owing to the dynamic aspects of the magnetic ordering process. Dependence of H th on material parameters and dot sizes has been systematically studied

  18. Modelling reverse characteristics of power LEDs with thermal phenomena taken into account

    International Nuclear Information System (INIS)

    Ptak, Przemysław; Górecki, Krzysztof

    2016-01-01

    This paper refers to modelling characteristics of power LEDs with a particular reference to thermal phenomena. Special attention is paid to modelling characteristics of the circuit protecting the considered device against the excessive value of the reverse voltage and to the description of the temperature influence on optical power. The network form of the worked out model is presented and some results of experimental verification of this model for the selected diodes operating at different cooling conditions are described. The very good agreement between the calculated and measured characteristics is obtained

  19. Optical roughness BRDF model for reverse Monte Carlo simulation of real material thermal radiation transfer.

    Science.gov (United States)

    Su, Peiran; Eri, Qitai; Wang, Qiang

    2014-04-10

    Optical roughness was introduced into the bidirectional reflectance distribution function (BRDF) model to simulate the reflectance characteristics of thermal radiation. The optical roughness BRDF model stemmed from the influence of surface roughness and wavelength on the ray reflectance calculation. This model was adopted to simulate real metal emissivity. The reverse Monte Carlo method was used to display the distribution of reflectance rays. The numerical simulations showed that the optical roughness BRDF model can calculate the wavelength effect on emissivity and simulate the real metal emissivity variance with incidence angles.

  20. Extraction and LC determination of lysine clonixinate salt in water/oil microemulsions.

    Science.gov (United States)

    Pineros, I; Ballesteros, P; Lastres, J L

    2002-02-01

    A new reversed-phase high performance liquid chromatography method has been developed and validated for the quantitative determination of lysine clonixinate salt in water/oil microemulsions. The mobile phase was acetonitrile-buffer phosphate pH 3.3. Detection was UV absorbance at 252 nm. The precision and accurately of the method were excellent. The established linearity range was 5-60 microg ml(-1) (r(2)=0.999). Microemulsions samples were dispersed with chloroform and extracted lysine clonixinate salt with water. This easy method employing chloroformic extraction has been done three times. The recovery of lysine clonixinate salt from spiked placebo and microemulsion were >90% over the linear range.

  1. Influence of microemulsions on cutaneous drug delivery

    DEFF Research Database (Denmark)

    Kreilgaard, Mads

    2002-01-01

    In attempt to increase cutaneous drug delivery, microemulsion vehicles have been more and more frequently employed over recent years. Microemulsion formulations have been shown to be superior for both transdermal and dermal delivery of particularly lipophilic compounds, but also hydrophilic...... compounds appear to benefit from application in microemulsions compared to conventional vehicles, like hydrogels, emulsions and liposomes. The favourable drug delivery properties of microemulsions appear to mainly be attributed to the excellent solubility properties. However, the vehicles may also act...... as penetration enhancers depending on the oil/surfactant constituents, which involves a risk of inducing local irritancy. The correlation between microemulsion structure/composition and drug delivery potential is not yet fully elucidated. However, a few studies have indicated that the internal structure...

  2. Structure-activity relationship of a u-type antimicrobial microemulsion system.

    Directory of Open Access Journals (Sweden)

    Hui Zhang

    Full Text Available The structure-activity relationship of a U-type antimicrobial microemulsion system containing glycerol monolaurate and ethanol at a 1∶1 mass ratio as oil phase and Tween 20 as surfactant were investigated along a water dilution line at a ratio of 80∶20 mass% surfactant/oil phase, based on a pseudo-ternary phase diagram. The differential scanning calorimetry results showed that in the region of up to 33% water, all water molecules are confined to the hydrophilic core of the reverse micelles, leading to the formation of w/o microemulsion. As the water content increases, the water gains mobility, and transforms into bicontinuous in the region of 33-39% water, and finally the microemulsion become o/w in the region of above 39% water. The microstructure characterization was confirmed by the dynamic light scattering measurements and freeze-fracture transmission electron microscope observation. The antimicrobial activity assay using kinetics of killing analysis demonstrated that the microemulsions in w/o regions exhibited relatively high antimicrobial activity against Escherichia coli and Staphylococcus aureus due to the antimicrobial oil phase as the continuous phase, while the antimicrobial activity started to decrease when the microemulsions entered the bicontinuous region, and decreased rapidly as the water content increased in the o/w region, as a result of the dilution of antimicrobial oil droplets in the aqueous continuous phase.

  3. Recording-media-related morphology and magnetic properties of crystalline CoPt{sub 3} and CoPt{sub 3}-Au core-shell nanoparticles synthesized via reverse microemulsion

    Energy Technology Data Exchange (ETDEWEB)

    Bahmanrokh, Ghazaleh, E-mail: ghazalehbahmanrokh@yahoo.com; Hashim, Mansor; Matori, Khamirul Amin; Kanagesan, Samikannu; Sabbaghizadeh, Rahim; Ezzad Shafie, Mohd Shamsul [Materials Synthesis and Characterization Laboratory, Institute of Advanced Technology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Navasery, Manizheh; Soltani, Nayereh [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor (Malaysia); Vaziri, Parisa [Department of Medical Physics and Biomedical Engineering, Shahid Beheshti University of Medical Sciences, Tehran (Iran, Islamic Republic of)

    2014-09-07

    A comparative experimental study of the magnetic properties of CoPt{sub 3} and CoPt{sub 3}/Au nanoparticles as well as a detailed study of the structural properties of the samples by X-ray diffraction, Transmission electron microscopy, and vibrating sample magnetometer is presented in this work. In addition, the effect of particle size on the structure and magnetic properties of nanoparticles prepared by microemulsion is studied. The correlation between particle size, crystallinity, and magnetization was studied as well. CoPt nanoparticles have been studied intensively over the last decade because of their increased magnetic anisotropy in the ordered phase that can be interesting for high density magnetic recording. A significant high coercivity for as-prepared CoPt{sub 3} and CoPt{sub 3}-Au nanoparticles was obtained at room temperature and enhanced after annealing. The focused aim of our study is to obtain high coercivity at room temperature that follows the Curie-Weiss law. This indicates an interacting system in which the nanoparticles behave like single domain ferromagnetic materials in the particle size range of 8 to 35 nm. In addition, the interaction increases by cooling the samples to low temperature around 15 K. Temperature dependence 1/M graph was obtained to investigate the behavior of nanoparticles at low temperature and shows the best fit with Curie-Weis mode.

  4. Thermal instabilities in the edge region of reversed-field pinches

    International Nuclear Information System (INIS)

    Goedert, J.; Mondt, J.P.

    1984-04-01

    Thermal stability of the edge region of reversed-field pinch configurations is analyzed within the context of a two-fluid model. Two major sources of instability are identified in combination with a parallel electric field: either an electron temperature gradient and/or a density gradient that leads to rapid growth (of several to many ohmic heating rates) over a region of several millimeters around the mode-rational surfaces in the edge region. The basic signature of both instabilities is electrostatic. In the case of the density gradient mode, the signature relies on the effects of electron compressibility, whereas the temperature gradient mode can be identified as the current-convective instability by taking the limit of zero diamagnetic drift, density gradient, thermal force, drift heat flux, and electron compressibility

  5. Pore Scale Dynamics of Microemulsion Formation.

    Science.gov (United States)

    Unsal, Evren; Broens, Marc; Armstrong, Ryan T

    2016-07-19

    Experiments in various porous media have shown that multiple parameters come into play when an oleic phase is displaced by an aqueous solution of surfactant. In general, the displacement efficiency is improved when the fluids become quasi-miscible. Understanding the phase behavior oil/water/surfactant systems is important because microemulsion has the ability to generate ultralow interfacial tension (microemulsion formation and the resulting properties under equilibrium conditions. However, the majority of applications where microemulsion is present also involve flow, which has received relatively less attention. It is commonly assumed that the characteristics of an oil/water/surfactant system under flowing conditions are identical to the one under equilibrium conditions. Here, we show that this is not necessarily the case. We studied the equilibrium phase behavior of a model system consisting of n-decane and an aqueous solution of olefin sulfonate surfactant, which has practical applications for enhanced oil recovery. The salt content of the aqueous solution was varied to provide a range of different microemulsion compositions and oil-water interfacial tensions. We then performed microfluidic flow experiments to study the dynamic in situ formation of microemulsion by coinjecting bulk fluids of n-decane and surfactant solution into a T-junction capillary geometry. A solvatochromatic fluorescent dye was used to obtain spatially resolved compositional information. In this way, we visualized the microemulsion formation and the flow of it along with the excess phases. A complex interaction between the flow patterns and the microemulsion properties was observed. The formation of microemulsion influenced the flow regimes, and the flow regimes affected the characteristics of the microemulsion formation. In particular, at low flow rates, slug flow was observed, which had profound consequences on the pore scale mixing behavior and resulting microemulsion properties.

  6. Experiment-based thermal micromagnetic simulations of the magnetization reversal for ns-range clocked nanomagnetic logic

    Science.gov (United States)

    Ziemys, Grazvydas; Breitkreutz-v. Gamm, Stephan; Csaba, Gyorgy; Schmitt-Landsiedel, Doris; Becherer, Markus

    2017-05-01

    Extensive thermal micromagnetic simulations, based on experimental data and parameters, were performed to investigate the magnetization reversal in Co/Pt nanomagnets with locally reduced perpendicular anisotropy on the nanosecond range. The simulations were supported by experimental data gained on manufactured Co/Pt nanomagnets, as used in nanomagnetic logic. It is known that magnetization reversal is governed by two mechanisms. At pulse lengths longer than 100 ns, thermal activation dominates the magnetization reversal processes and follows the common accepted Arrhenius law. For pulse lengths shorter than 100 ns, the dynamic reversal dominates. With the help of thermal micro-magnetic simulations we found out that the point where the both mechanisms meet is determined by the damping constant α of the multilayer film stack. The optimization of ferromagnetic multilayer film stacks enables higher clocking rates with lower power consumption and, therefore, further improve the performance of pNML.

  7. Co-surfactant free microemulsions: Preparation, characterization and stability evaluation for food application.

    Science.gov (United States)

    Xu, Zhenbo; Jin, Jun; Zheng, Minying; Zheng, Yan; Xu, Xuebing; Liu, Yuanfa; Wang, Xingguo

    2016-08-01

    The aim of the study is to prepare co-surfactant free microalgal oil microemulsions and investigate their properties as well as processing stability for food application. The physicochemical characteristics of the microemulsions were investigated by dynamic light scattering (DLS), turbidity, conductivity, rheological measurements and transmission electron microscopy (TEM). Within the microemulsion region, when the surfactant to oil ratio was 9:1, the hydrodynamic diameter (Dh) was 18nm; when the surfactant to oil ratio was 7.5:1, the hydrodynamic diameter (Dh) was 50nm. Rheological studies proved that the microemulsion system was a pseudoplastic fluid, which followed a shear thinning flow behavior. The loss rate of docosahexaenoic acid (DHA) was less than 5%wt after ultra high temperature (UHT) and high temperature short time (HTST) thermal treatments. A high content of CaCl2 (10.0%wt) could not destroy the microemulsion system, and it could be stored at 4°C for two years. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. The convection patterns in microemulsions

    International Nuclear Information System (INIS)

    Korneta, W.; Lopez Quintela, M.A.; Fernandez Novoa, A.

    1991-07-01

    The Rayleigh-Benard convection in the microemulsion consisting of water (7.5%), cyclohexan (oil-61.7%) and diethylenglycolmonobutylether (surfactant-30.8%) is studied from the onset of convection to the phase separation. The five classes of convection patterns are observed and recorded on the video: localized travelling waves, travelling waves, travelling waves and localized steady rolls, steady rolls and steady polygons. The Fourier transforms and histograms of these patterns are presented. The origin of any pattern is discussed. The intermittent behaviour close to the phase separation was observed. Possible applications of the obtained results are suggested. (author). 6 refs, 4 figs

  9. Anionic microemulsion to solvent stacking for on-line sample concentration of cationic analytes in capillary electrophoresis.

    Science.gov (United States)

    Kukusamude, Chunyapuk; Srijaranai, Supalax; Quirino, Joselito P

    2014-05-01

    The common SDS microemulsion (i.e. 3.3% SDS, 0.8% octane, and 6.6% butanol) and organic solvents were investigated for the stacking of cationic drugs in capillary zone electrophoresis using a low pH separation electrolyte. The sample was prepared in the acidic microemulsion and a high percentage of organic solvent was included in the electrolyte at anodic end of capillary. The stacking mechanism was similar to micelle to solvent stacking where the micelles were replaced by the microemulsion for the transport of analytes to the organic solvent rich boundary. This boundary is found between the microemulsion and anodic electrolyte. The effective electrophoretic mobility of the cations reversed from the direction of the anode in the microemulsion to the cathode in the boundary. Microemulsion to solvent stacking was successfully achieved with 40% ACN in the anodic electrolyte and hydrodynamic sample injection of 21 s at 1000 mbar (equivalent to 30% of the effective length). The sensitivity enhancement factors in terms of peak height and corrected peak area were 15 to 35 and 21 to 47, respectively. The linearity R(2) in terms of corrected peak area were >0.999. Interday precisions (%RSD, n = 6) were 3.3-4.0% for corrected peak area and 2.0-3.0% for migration time. Application to spiked real sample is also presented. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Mechanism of Thermal Reversal of the (Fulvalene)tetracarbonyldiruthenium Photoisomerization: Toward Molecular Solar-Thermal Energy Storage

    Energy Technology Data Exchange (ETDEWEB)

    Kanai, Y; Srinivasan, V; Meier, S K; Vollhardt, K P; Grossman, J C

    2010-02-18

    In the currently intensifying quest to harness solar energy for the powering of our planet, most efforts are centered around photoinduced generic charge separation, such as in photovoltaics, water splitting, other small molecule activation, and biologically inspired photosynthetic systems. In contrast, direct collection of heat from sunlight has received much less diversified attention, its bulk devoted to the development of concentrating solar thermal power plants, in which mirrors are used to focus the sun beam on an appropriate heat transfer material. An attractive alternative strategy would be to trap solar energy in the form of chemical bonds, ideally through the photoconversion of a suitable molecule to a higher energy isomer, which, in turn, would release the stored energy by thermal reversal. Such a system would encompass the essential elements of a rechargeable heat battery, with its inherent advantages of storage, transportability, and use on demand. The underlying concept has been explored extensively with organic molecules (such as the norbornadiene-quadricyclane cycle), often in the context of developing photoswitches. On the other hand, organometallic complexes have remained relatively obscure in this capacity, despite a number of advantages, including expanded structural tunability and generally favorable electronic absorption regimes. A highly promising organometallic system is the previously reported, robust photo-thermal fulvalene (Fv) diruthenium couple 1 {l_reversible} 2 (Scheme 1). However, although reversible and moderately efficient, lack of a full, detailed atom-scale understanding of its key conversion and storage mechanisms have limited our ability to improve on its performance or identify optimal variants, such as substituents on the Fv, ligands other than CO, and alternative metals. Here we present a theoretical investigation, in conjunction with corroborating experiments, of the mechanism for the heat releasing step of 2 {yields} 1 and

  11. Influence of microemulsion-mucin interaction on the fate of microemulsions diffusing through pig gastric mucin solutions.

    Science.gov (United States)

    Zhang, Jianbin; Lv, Yan; Wang, Bing; Zhao, Shan; Tan, Mingqian; Lv, Guojun; Ma, Xiaojun

    2015-03-02

    Mucus layer, a selective diffusion barrier, has an important effect on the fate of drug delivery systems in the gastrointestinal tract. To study the fate of microemulsions in the mucus layer, four microemulsion formulations with different particle sizes and lipid compositions were prepared. The microemulsion-mucin interaction was demonstrated by the fluorescence resonance energy transfer (FRET) method. Moreover, the microemulsions were observed aggregated into micron-sized emulsions by laser confocal microscopy. We concluded the microemulsion-mucin interaction not only led to microemulsions closely adhered to mucins but also destroyed the structure of microemulsions. At last, the diffusion of blank microemulsions and microemulsion-carried drugs (resveratrol and hymecromone) through mucin solutions was determined by the fluorescence recovery after photobleaching (FRAP) method and the Franz diffusion cell method. The results demonstrated the diffusion of microemulsions was significantly hindered by mucin solutions. The particle size of microemulsions had a negligible effect on the diffusion coefficients. However, the type of lipid played an important role, which could form hydrophobic interactions with mucins. Interestingly, microemulsion-carried drugs with different core/shell locations seemed to suffer different fates in the mucin solutions. The drug incorporated in the oil core of microemulsions, resveratrol, was transported through the mucus layer by the carriers, while the drug incorporated in the surfactant shell of microemulsions, hymecromone, was separated from the carriers and diffused toward the epithelium in the form of free molecules.

  12. Magnetic Reversal and Thermal Stability of CoFeB Perpendicular Magnetic Tunnel Junction Arrays Patterned by Block Copolymer Lithography

    KAUST Repository

    Tu, Kun-Hua

    2018-04-10

    Dense arrays of pillars, with diameters of 64 and 25 nm, were made from a perpendicular CoFeB magnetic tunnel junction thin film stack using block copolymer lithography. While the soft layer and hard layer in the 64 nm pillars reverse at different fields, the reversal of the two layers in the 25 nm pillars could not be distinguished, attributed to the strong interlayer magnetostatic coupling. First order reversal curves were used to identify the steps that occur during switching, and the thermal stability and effective switching volume were determined from scan rate dependent hysteresis measurements.

  13. Thermally responsive polymer systems for self-healing, reversible adhesion and shape memory applications

    Science.gov (United States)

    Luo, Xiaofan

    Responsive polymers are "smart" materials that are capable of performing prescribed, dynamic functions under an applied stimulus. In this dissertation, we explore several novel design strategies to develop thermally responsive polymers and polymer composites for self-healing, reversible adhesion and shape memory applications. In the first case described in Chapters 2 and 3, a thermally triggered self-healing material was prepared by blending a high-temperature epoxy resin with a thermoplastic polymer, poly(epsilon-caprolactone) (PCL). The initially miscible system undergoes polymerization induced phase separation (PIPS) during the curing of epoxy and yields a variety of compositionally dependent morphologies. At a particular PCL loading, the cured blend displays a "bricks-and-mortar" morphology in which epoxy exists as interconnected spheres ("bricks") within a continuous PCL matrix ("mortar"). A heat induced "bleeding" phenomenon was observed in the form of spontaneous wetting of all free surfaces by the molten PCL, and is attributed to the volumetric thermal expansion of PCL above its melting point in excess of epoxy brick expansion, which we term differential expansive bleeding (DEB). This DEB is capable of healing damage such as cracks. In controlled self-healing experiments, heating of a cracked specimen led to PCL bleeding from the bulk that yields a liquid layer bridging the crack gap. Upon cooling, a "scar" composed of PCL crystals was formed at the site of the crack, restoring a significant portion of mechanical strength. We further utilized DEB to enable strong and thermally-reversible adhesion of the material to itself and to metallic substrates, without any requirement for macroscopic softening or flow. After that, Chapters 4--6 present a novel composite strategy for the design and fabrication of shape memory polymer composites. The basic approach involves physically combining two or more functional components into an interpenetrating fiber

  14. Evaluation of using ferrofluid as an interface material for a field-reversible thermal connector

    Science.gov (United States)

    Yousif, Ahmed S.

    The electrical functionality of an avionics chassis is limited due to heat dissipation limits. The limits arise due to the fact that components in an avionic computer boxes are packed very compactly, with the components mounted onto plug-in cards, and the harsh environment experienced by the chassis limits how heat can be dissipated from the cards. Convective and radiative heat transfer to the ambient are generally not possible. Therefore it is necessary to have heat transferred from the components conducted to the edge of the plug-in cards. The heat then needs to conduct from the card edge to a cold block that not only holds the card in place, but also removes the generated heat by some heat transfer fluid that is circulated through the cold block. The interface between the plug-in card and the cold block typically has a high thermal resistance since it is necessary for the card to have the capability to be re-workable, meaning that the card can be removed and then returned to the chassis. Reducing the thermal resistance of the interface is the objective of the current study and the topic of this thesis. The current design uses a pressure interface between the card and cold block. The contact pressure is increased through the addition of a wedgelock, which is a field-reversible mechanical connector. To use a wedgelock, the cold block has channels milled on the surface with widths that are larger than the thickness of the plug-in card and the un-expanded wedgelock. The card edge is placed in the channel and placed against one of the channel walls. A wedgelock is then placed between the card and the other channel wall. The wedgelock is then expanded by using either a screw or a lever. As the wedgelock expands it fills in the remaining channel gap and bears against the other face of the plug-in card. The majority of heat generated by the components on the plug-in card is forced to conduct from the card into the wall of the cold block, effectively a single sided, dry

  15. Microemulsion and Microemulsion-Based Gels for Topical Antifungal Therapy with Phytochemicals.

    Science.gov (United States)

    Boonme, Prapaporn; Kaewbanjong, Jarika; Amnuaikit, Thanaporn; Andreani, Tatiana; Silva, Amélia M; Souto, Eliana B

    2016-01-01

    Skin fungal infections are regular injuries suffered by people living in tropical areas. Most common pathogens are Trichophyton, Microsporum and Epidermophyton which can cause skin lesions in many parts of body. Topical antifungal phytochemicals are commonly used to avoid systemic adverse events and are more convenient for patient application than those administered by other routes. However, the effectiveness of topical treatments in eradicating fungal infection is more limited since the stratum corneum acts as the skin barrier, resulting in long treatment duration and low patient's compliance. The goal of this work is to identify optimized drug delivery systems to improve topic clinical efficacy. Microemulsions i.e. liquid dispersions of oil and water stabilized with an interfacial film of surfactant are well known drug delivery systems. A thickening agent may be included to form microemulsion-based gels to increase skin adhesion. Microemulsions and microemulsion-based gels can be loaded with several hydrophilic and lipophilic drugs because they are composed of both water and oil phases. Microemulsions and microemulsion-based gels can also be used for the delivery of many drugs including antifungal drugs through stratum corneum due to their capacity to act as skin penetration enhancement. In addition to a comprehensive review of microemulsion and microemulsion-based gels as suitable carriers for skin delivery of various antifungal drugs, this review also aims to discuss the delivery of antifungal phytochemicals.

  16. The Reverse Thermal Effect in Epoxy Resins and Moisture Absorption in Semi-Interpenetrating Polymer Networks.

    Science.gov (United States)

    El-Sa'Ad, Leila

    1989-12-01

    termed the "reverse thermal effect". The swelling results suggested that it is more tightly bound water in the polymer which takes part in the reverse thermal effect. The absorption results for the Semi-Interpenetrating Polymer Networks suggested that the two key parameters which affected the moisture uptake were the morphology of the network and the percentage of epoxy resin in the system.

  17. Reversible switching of wetting properties and erasable patterning of polymer surfaces using plasma oxidation and thermal treatment

    Science.gov (United States)

    Rashid, Zeeshan; Atay, Ipek; Soydan, Seren; Yagci, M. Baris; Jonáš, Alexandr; Yilgor, Emel; Kiraz, Alper; Yilgor, Iskender

    2018-05-01

    Polymer surfaces reversibly switchable from superhydrophobic to superhydrophilic by exposure to oxygen plasma and subsequent thermal treatment are demonstrated. Two inherently different polymers, hydrophobic segmented polydimethylsiloxane-urea copolymer (TPSC) and hydrophilic poly(methyl methacrylate) (PMMA) are modified with fumed silica nanoparticles to prepare superhydrophobic surfaces with roughness on nanometer to micrometer scale. Smooth TPSC and PMMA surfaces are also used as control samples. Regardless of their chemical structure and surface topography, all surfaces display completely reversible wetting behavior changing from hydrophobic to hydrophilic and back for many cycles upon plasma oxidation followed by thermal annealing. Influence of plasma power, plasma exposure time, annealing temperature and annealing time on the wetting behavior of polymeric surfaces are investigated. Surface compositions, textures and topographies are characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and white light interferometry (WLI), before and after oxidation and thermal annealing. Wetting properties of the surfaces are determined by measuring their static, advancing and receding water contact angle. We conclude that the chemical structure and surface topography of the polymers play a relatively minor role in reversible wetting behavior, where the essential factors are surface oxidation and migration of polymer molecules to the surface upon thermal annealing. Reconfigurable water channels on polymer surfaces are produced by plasma treatment using a mask and thermal annealing cycles. Such patterned reconfigurable hydrophilic regions can find use in surface microfluidics and optofluidics applications.

  18. Formulation and In-vivo Pharmacokinetic Consideration of Intranasal Microemulsion and Mucoadhesive Microemulsion of Rivastigmine for Brain Targeting.

    Science.gov (United States)

    Shah, Brijesh; Khunt, Dignesh; Misra, Manju; Padh, Harish

    2018-01-02

    Presence of tight junctions in blood brain barrier (BBB) pose a major hurdle for delivery of drug and severely affects adequate therapeutic concentration to reach the brain. In present work, we have selected Rivastigmine hydrogen tartrate (RHT), a reversible cholinesterase inhibitor, which exhibits extensive first-pass metabolism, resulting in limited absolute bioavailability (36%). RHT shows extremely low aqueous solubility and poor penetration, resulting in inadequate concentration reaching the brain, thus necessitating frequent oral dosing. To overcome these problems of RHT, microemulsion (ME) and mucoadhesive microemulsion (MME) of RHT were formulated for brain targeting via intranasal delivery route and compared on the basis of in vivo pharmacokinetics. ME and MME formulations containing RHT were developed by water titration method. Characterization of ME and MME was done for various physicochemical parameters, nasal spray pattern, and in vivo pharmacokinetics quantitatively and qualitatively (gamma scintigraphy studies). The developed ME and MME were transparent having globule size approximately in the range of 53-55 nm. Pharmacokinetic studies showed higher values for C max and DTP for intranasal RHT: CH-ME over RHT-ME, thus indicating the effect of chitosan in modulating tight junctions, thereby enhanced paracellular transport of RHT. Gamma scintigraphy and in vivo pharmacokinetic study suggested enhanced RHT concentration, upon intranasal administration of RHT:CH-ME, compare with other groups administered formulations intranasally. These findings suggested the potential of non-invasive intranasal route for brain delivery, especially for therapeutics, facing challenges in oral administration.

  19. Transdermal delivery of diclofenac using microemulsions.

    Science.gov (United States)

    Kweon, Jang-Hoon; Chi, Sang-Cheol; Park, Eun-Seok

    2004-03-01

    A transdermal preparation containing diclofenac diethylammonium (DDA) was developed using an O/W microemulsion system. Of the oils tested, lauryl alcohol was chosen as the oil phase of the microemulsion, as it showed a good solubilizing capacity and excellent skin permeation rate of the drug. Pseudoternary phase diagrams were constructed to obtain the concentration range of oil, surfactant and cosurfactant for microemulsion formation, and the effect of these additives on skin permeation of DDA was evaluated with excised rat skins. The optimum formulation of the microemulsion consisted of 1.16% of DDA, 5% of lauryl alcohol, 60% of water in combination with the 34.54% of Labrasol (surfactant)/ethanol (cosurfactant) (1:2). The efficiency of formulation in the percutaneous absorption of DDA was dependent upon the contents of water and lauryl alcohol as well as Labrasol:ethanol mixing ratio. It was concluded that the percutaneous absorption of DDA from microemulsions was enhanced with increasing the lauryl alcohol and water contents, and with decreasing the Labrasol:ethanol mixing ratio in the formulation.

  20. Microemulsion systems applied to breakdown petroleum emulsions

    Energy Technology Data Exchange (ETDEWEB)

    Neuma de Castro Dantas, Tereza; Avelino Dantas Neto, Afonso; Ferreira Moura, Everlane [Deptos de Quimica e Eng. Quimica, Universidade Federal do Rio Grande do Norte, Campus Universitario s/n, 59072.970, Natal/RN Campinas (Brazil)

    2001-12-29

    Microemulsion systems obtained using commercial surfactants with demulsifier and emulsion prevention properties have been employed to break down Brazilian crude water-in-oil (W/O) emulsions. These crude oils were supplied by the Brazilian oil company-PETROBRAS-and were characterized by the different Balance sheet of Sediment and Water (BSW) values of 48%, 36%, and 32%. The microemulsion systems formed in this study were composed of an aqueous phase (HCl 5.2% solution); an oil phase (toluene); a cosurfactant/surfactant (C/S) phase (isopropyl alcohol (C)/surfactants (S) with a ratio C/S of 9.0). The microemulsion efficiency to break down oil emulsions was evaluated by a direct contact method between the microemulsions and crude (W/O) emulsions. The Scheffe net statistical planning for mixtures was used to relate the component mass fractions to the relative breakdown of petroleum emulsions. The best composition of the microemulsion system for the complete breakdown of oil emulsions with high BSW values had the lowest C/S phase percentage.

  1. Reversal mechanisms and interactions in magnetic systems: coercivity versus switching field and thermally assisted demagnetization

    Directory of Open Access Journals (Sweden)

    Cebollada, F.

    2005-06-01

    Full Text Available In this paper we present a comparative analysis of the magnetic interactions and reversal mechanisms of two different systems: NdFeB-type alloys with grain sizes in the single domain range and Fe-SiO2 nanocomposites with Fe concentrations above and below the percolation threshold. We evidence that the use of the coercivity as the main parameter to analyse them might be misleading due to the convolution of both reversible and irreversible magnetization variations. We show that the switching field and thermally assisted demagnetization allow a better understanding of these mechanisms since they involve just irreversible magnetization changes. Specifically, the experimental analysis of the coercivity adquisition process for the NdFeB-type system suggests that the magnetization reversal is nucleated at the spin misalignments present due to intergranular exchange interactions. On the other hand, the study of the magnetic viscosity and of the isothermal remanent magnetization (IRM and direct field demagnetization (DCD remanence curves indicates that the dipolar interactions are responsible for the propagation of the switching started at individual particles.

    En este artículo presentamos un análisis comparativo de la influencia de la microestructura a través de las interacciones magnéticas en los mecanismos de inversión de la magnetización en dos sistemas diferentes: aleaciones tipo NdFeB con tamaños de grano en el rango de monodominio y nanocompuestos de Fe-SiO2 con concentraciones de Fe tanto por encima como por debajo del umbral de percolación. Ponemos de manifiesto que el uso del campo coercitivo como parámetro de análisis puede llevar a equívocos debido a la coexistencia de variaciones reversibles e irreversibles de la magnetización. También mostramos que el campo de conmutación y la desimanación térmicamente asistida permiten una mejor comprensión de dichos mecanismos ya que reflejan exclusivamente cambios irreversibles de

  2. Non-monotonic probability of thermal reversal in thin-film biaxial nanomagnets with small energy barriers

    Directory of Open Access Journals (Sweden)

    N. Kani

    2017-05-01

    Full Text Available The goal of this paper is to investigate the short time-scale, thermally-induced probability of magnetization reversal for an biaxial nanomagnet that is characterized with a biaxial magnetic anisotropy. For the first time, we clearly show that for a given energy barrier of the nanomagnet, the magnetization reversal probability of an biaxial nanomagnet exhibits a non-monotonic dependence on its saturation magnetization. Specifically, there are two reasons for this non-monotonic behavior in rectangular thin-film nanomagnets that have a large perpendicular magnetic anisotropy. First, a large perpendicular anisotropy lowers the precessional period of the magnetization making it more likely to precess across the x^=0 plane if the magnetization energy exceeds the energy barrier. Second, the thermal-field torque at a particular energy increases as the magnitude of the perpendicular anisotropy increases during the magnetization precession. This non-monotonic behavior is most noticeable when analyzing the magnetization reversals on time-scales up to several tens of ns. In light of the several proposals of spintronic devices that require data retention on time-scales up to 10’s of ns, understanding the probability of magnetization reversal on the short time-scales is important. As such, the results presented in this paper will be helpful in quantifying the reliability and noise sensitivity of spintronic devices in which thermal noise is inevitably present.

  3. Application of microemulsion in oil production operations; Emprego de microemulsao na producao de petroleo

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Marcia Cristina K. de; Gonzalez, Gaspar [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil). Centro de Pesquisas

    2008-07-01

    Microemulsions are thermodynamically stable liquid-liquid dispersions that present a wide range of potential applications in the Petroleum Industry due to their high stability, ultralow interfacial tension and capacity to modify the wettability of the solids eventually present in the system. In this work some specific application such as removal of deposits from solid surfaces, oily sludge separation, heavy oil recovery from consolidated porous media and oil mobilization from limestone cores, currently under examination at PETROBRAS, are reviewed. It has been found that heavy oil fraction strongly attached to solid surfaces can be removed up to above 90% in the case solids contaminated with oil previously treated by thermal desorption or for sand contaminated with crude oil. Tests with field samples of oily sludge showed that these contaminants can readily be resolved into oil, water and free loose solid particles. In fluid injection tests using consolidated porous media it was observed that the injection of microemulsion after secondary oil removal with sea water conduced to an additional recovery of 59%. Qualitative tests carried out with consolidated limestone cores impregnated with crude oil showed that the oil was efficiently displaced by microemulsion. This effect has been ascribed to the rock matrix wettability inversion caused by the microemulsion. (author)

  4. Overcoming the Cutaneous Barrier with Microemulsions

    Science.gov (United States)

    Lopes, Luciana B.

    2014-01-01

    Microemulsions are fluid and isotropic formulations that have been widely studied as delivery systems for a variety of routes, including the skin. In spite of what the name suggests, microemulsions are nanocarriers, and their use as topical delivery systems derives from their multiple advantages compared to other dermatological formulations, such as ease of preparation, thermodynamic stability and penetration-enhancing properties. Composition, charge and internal structure have been reported as determinant factors for the modulation of drug release and cutaneous and transdermal transport. This manuscript aims at reviewing how these and other characteristics affect delivery and make microemulsions appealing for topical and transdermal administration, as well as how they can be modulated during the formulation design to improve the potential and efficacy of the final system. PMID:24590260

  5. Overcoming the Cutaneous Barrier with Microemulsions

    Directory of Open Access Journals (Sweden)

    Luciana B. Lopes

    2014-02-01

    Full Text Available Microemulsions are fluid and isotropic formulations that have been widely studied as delivery systems for a variety of routes, including the skin. In spite of what the name suggests, microemulsions are nanocarriers, and their use as topical delivery systems derives from their multiple advantages compared to other dermatological formulations, such as ease of preparation, thermodynamic stability and penetration-enhancing properties. Composition, charge and internal structure have been reported as determinant factors for the modulation of drug release and cutaneous and transdermal transport. This manuscript aims at reviewing how these and other characteristics affect delivery and make microemulsions appealing for topical and transdermal administration, as well as how they can be modulated during the formulation design to improve the potential and efficacy of the final system.

  6. Transdermal delivery of curcumin via microemulsion.

    Science.gov (United States)

    Sintov, Amnon C

    2015-03-15

    The objective of this study was to evaluate the transdermal delivery potential of a new curcumin-containing microemulsion system. Three series of experiments were carried out to comprehend the system characteristics: (a) examining the influence of water content on curcumin permeation, (b) studying the effect of curcumin loading on its permeability, and (c) assessing the contribution of the vesicular nature of the microemulsion on permeability. The skin permeability of curcumin from microemulsions, which contained 5%, 10%, and 20% of water content (1% curcumin), was measured in vitro using excised rat skin. It has been shown that the permeability coefficient of CUR in a formulation containing 10% aqueous phase (ME-10) was twofold higher than the values obtained for formulations with 5% and 20% water (Papp=0.116 × 10(-3)± 0.052 × 10(-3)vs. 0.043 × 10(-3)± 0.022 × 10(-3) and 0.047 × 10(-3)± 0.025 × 10(-3)cm/h, respectively. A reasonable explanation for this phenomenon may be the reduction of both droplet size and droplets' concentration in the microemulsion as the aqueous phase decreased from 20% to 5%. It has also been shown that a linear correlation exists between the decrease in droplet size and the increase of curcumin loading in the microemulsion. In addition, it has been demonstrated that a micellar system, S/O-mix, and a plain solution of curcumin resulted in a significantly lower curcumin permeation relative to that presented by the microemulsion, Papp=0.018 × 10(-3)± 0.011 × 10(-3), 0.005 × 10(-3)± 0.002 × 10(-3), and 0.002 × 10(-3)± 0.000 × 10(-3)cm/h, respectively, vs. 0.110 × 10(-3)± 0.021 × 10(-3)cm/h for the microemulsion. The enhancement ratio (ER=Jss-ME/Jss-solution) of CUR permeated via 1% loaded microemulsion was 55. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Extensively Reversible Thermal Transformations of a Bistable, Fluorescence-Switchable Molecular Solid: Entry into Functional Molecular Phase-Change Materials.

    Science.gov (United States)

    Srujana, P; Radhakrishnan, T P

    2015-06-15

    Functional phase-change materials (PCMs) are conspicuously absent among molecular materials in which the various attributes of inorganic solids have been realized. While organic PCMs are primarily limited to thermal storage systems, the amorphous-crystalline transformation of materials like Ge-Sb-Te find use in advanced applications such as information storage. Reversible amorphous-crystalline transformations in molecular solids require a subtle balance between robust supramolecular assembly and flexible structural elements. We report novel diaminodicyanoquinodimethanes that achieve this transformation by interlinked helical assemblies coupled with conformationally flexible alkoxyalkyl chains. They exhibit highly reversible thermal transformations between bistable (crystalline/amorphous) forms, along with a prominent switching of the fluorescence emission energy and intensity. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Monte Carlo simulation for thermal assisted reversal process of micro-magnetic torus ring with bistable closure domain structure

    Energy Technology Data Exchange (ETDEWEB)

    Terashima, Kenichi; Suzuki, Kenji; Yamaguchi, Katsuhiko, E-mail: yama@sss.fukushima-u.ac.jp

    2016-04-01

    Monte Carlo simulations were performed for temperature dependences of closure domain parameter for a magnetic micro-torus ring cluster under magnetic field on limited temperature regions. Simulation results show that magnetic field on tiny limited temperature region can reverse magnetic closure domain structures when the magnetic field is applied at a threshold temperature corresponding to intensity of applied magnetic field. This is one of thermally assisted switching phenomena through a self-organization process. The results show the way to find non-wasteful pairs between intensity of magnetic field and temperature region for reversing closure domain structure by temperature dependence of the fluctuation of closure domain parameter. Monte Carlo method for this simulation is very valuable to optimize the design of thermally assisted switching devices.

  9. Catalytic Study on TiO2 Photo catalyst Synthesised Via Microemulsion Method on Atrazine

    International Nuclear Information System (INIS)

    Ruslimie, C.A.; Hasmizam Razali; Khairul, W.M.

    2011-01-01

    Titanium dioxide photo catalyst was synthesised by microemulsions method under controlled hydrolysis of titanium butoxide, Ti(O(CH 2 ) 3 )CH 3 . The synthesised TiO 2 photo catalyst was compared with Sigma-commercial TiO 2 by carrying out the investigation on its properties using scanning electron microscopy (SEM), x-ray diffraction (XRD) analysis and thermal gravimetric analysis (TGA). The photo catalytic activities for both photo catalysts were studied for atrazine photodegradation. (author)

  10. Thermally reversible rubber-toughened thermoset networks via Diels-Alder chemistry

    NARCIS (Netherlands)

    Araya-Hermosilla, R.; Fortunato, G.; Pucci, A.; Raffa, P.; Polgar, L.; Broekhuis, A. A.; Pourhossein, P.; Lima, G. M. R.; Beljaars, M.; Picchioni, F.

    In this work we present a reversible and toughened thermoset system based on the covalent incorporation of a furane functionalized ethylene-propylene rubber (EPM-Fu) into a thermoset furane functionalized polyketone (PK-Fu) via Diels-Alder (DA) reversible cross-linking with bismaleimide (b-MA).

  11. Length scale for configurational entropy in microemulsions

    NARCIS (Netherlands)

    Reiss, H.; Kegel, W.K.; Groenewold, J.

    1996-01-01

    In this paper we study the length scale that must be used in evaluating the mixing entropy in a microemulsion. The central idea involves the choice of a length scale in configuration space that is consistent with the physical definition of entropy in phase space. We show that this scale may be

  12. Polymer association in a microemulsion system

    International Nuclear Information System (INIS)

    Fountain, L.E.; Shahidan Radiman; Toprakcioglu, C.

    1997-01-01

    Using small angle neutron scattering technique with appropriate contrast we have been able to elucidate some associations structures of polystyrene (PS) and triblock co-polymers of polyethylene oxide-polystyrene- polyethylene oxide (PEO-PS-PEO) in a water-in-oil microemulsion system

  13. Pressure-induced reversal between thermal contraction and expansion in ferroelectric PbTiO3

    OpenAIRE

    Jinlong Zhu; Jianzhong Zhang; Hongwu Xu; Sven C. Vogel; Changqing Jin; Johannes Frantti; Yusheng Zhao

    2014-01-01

    Materials with zero/near zero thermal expansion coefficients are technologically important for applications in thermal management and engineering. To date, this class of materials can only be produced by chemical routes, either by changing chemical compositions or by composting materials with positive and negative thermal expansion. Here, we report for the first time a physical route to achieve near zero thermal expansion through application of pressure. In the stability field of tetragonal P...

  14. Preparation of AgBr Nanoparticles in Microemulsions Via Reaction of AgNO3 with CTAB Counterion

    International Nuclear Information System (INIS)

    Husein, Maen M.; Rodil, Eva; Vera, Juan H.

    2007-01-01

    Nanoparticles of AgBr were prepared by precipitating AgBr in the water pools of microemulsions consisting of CTAB, n-butanol, isooctane and water. An aqueous solution of AgNO 3 added to the microemulsion was the source of Ag + ions. The formation of AgBr nanoparticles in microemulsions through direct reaction with the surfactant counterion is a novel approach aimed at decreasing the role of intermicellar nucleation on nanoparticle formation for rapid reactions. The availability of the surfactant counterion in every reverse micelle and the rapidity of the reaction with the counterion trigger nucleation within individual reverse micelles. The effect of the following variables on the particle size and size distribution was investigated: the surfactant and cosurfactant concentrations, moles of AgNO 3 added, and water to surfactant mole ratio, R. High concentration of the surfactant or cosurfactant, or high water content of the microemulsion favored intermicellar nucleation and resulted in the formation of large particles with broad size distribution, while high amounts of AgNO 3 favored nucleation within individual micelles and resulted in small nanoparticles with narrow size distribution. A blue shift in the UV absorption threshold corresponding to a decrease in the particle size was generally observed. Notably, the variation of the absorption peak size with the nanoparticle size was opposite to those reported by us in previous studies using different surfactants

  15. Development of cyclosporine A microemulsion for parenteral delivery.

    Science.gov (United States)

    Yuan, Yue; Che, Xin; Zhao, Mingyi; Wang, Yan; Liu, Yajun; Schwendeman, Anna; Li, Sanming

    2015-01-01

    The goal of this study was to develop a parenteral microemulsion formulation of cyclosporine A (CyA). The CyA solubility in caprylic capric triglyceride (GTCC), ethyl oleate and soybean oil were determined. The pseudo-ternary diagrams of oil (GTCC), surfactant (Solutol® HS-15), cosurfactants (ethanol/polyethylene glycol 400 [PEG 400] mixture) and water were constructed to identify boundaries for microemulsion existence. The CyA was added at 3, 6 and 9% w/w to the optimal microemulsion composition. Microemulsion particle size, solution viscosity and conductivity were examined. The microemulsion stability and haemolytic potential were examined after dilution in 5% dextrose solution for injection to 1 mg/mL CyA. Microemulsion stability was examined after a three-month storage at 4 and 25 °C. The GTCC was selected as an oil phase for CyA microemulsion based on solubility results. The optimum CyA microemulsion formulation consisted of 2.5% CyA, 9% GTCC, 24% Solutol® HS 15, 8% PEG 400, 4% ethanol and 52.5% water based on weight percent. The average particle sizes of the optimized blank and drug-loaded microemulsions were 68.7 nm and 71.6 nm, respectively and remained unchanged upon 25-fold dextrose dilution. The results of microemulsion physical and CyA chemical were confirmed by a three-month stability study at 4 and 25 °C. In vitro haemolysis studies indicated that CyA microemulsions were well tolerated by erythrocytes. The novel microemulsion formulation of CyA was developed that is suitable for parenteral administration. This new formulation could potentially have less vehicle-associated side effects that current commercial formulation of CyA based on Cremophor® EL and ethanol solution.

  16. Thermally activated magnetization reversal in monatomic magnetic chains on surfaces studied by classical atomistic spin-dynamics simulations

    International Nuclear Information System (INIS)

    Bauer, David S G; Mavropoulos, Phivos; Bluegel, Stefan; Lounis, Samir

    2011-01-01

    We analyse the spontaneous magnetization reversal of supported monatomic chains of finite length due to thermal fluctuations via atomistic spin-dynamics simulations. Our approach is based on the integration of the Landau-Lifshitz equation of motion of a classical spin Hamiltonian in the presence of stochastic forces. The associated magnetization lifetime is found to obey an Arrhenius law with an activation barrier equal to the domain wall energy in the chain. For chains longer than one domain wall width, the reversal is initiated by nucleation of a reversed magnetization domain primarily at the chain edge followed by a subsequent propagation of the domain wall to the other edge in a random-walk fashion. This results in a linear dependence of the lifetime on the chain length, if the magnetization correlation length is not exceeded. We studied chains of uniaxial and triaxial anisotropy and found that a triaxial anisotropy leads to a reduction of the magnetization lifetime due to a higher reversal attempt rate, even though the activation barrier is not changed.

  17. Microemulsion utility in pharmaceuticals: Implications for multi-drug delivery.

    Science.gov (United States)

    Callender, Shannon P; Mathews, Jessica A; Kobernyk, Katherine; Wettig, Shawn D

    2017-06-30

    Emulsion technology has been utilized extensively in the pharmaceutical industry. This article presents a comprehensive review of the literature on an important subcategory of emulsions, microemulsions. Microemulsions are optically transparent, thermodynamically stable colloidal systems, 10-100nm diameter, that form spontaneously upon mixing of oil, water and emulsifier. This review is the first to address advantages and disadvantages, as well as considerations and challenges in multi-drug delivery. For the period 1 January 2011-30 April 2016, 431 publications related to microemulsion drug delivery were identified and screened according to microemulsion, drug classification, and surfactant types. Results indicate the use of microemulsions predominantly in lipophilic drug delivery (79.4%) via oil-in-water microemulsions and non-ionic surfactants (90%) for oral or topical administration. Cancer is the disease state most targeted followed by inflammatory diseases, microbial infections and cardiovascular disease. Key generalizations from this analysis include: 1) microemulsion formulation is largely based on trial-and-error despite over 1200 publications related to microemulsion drug delivery since their discovery in 1943; 2) characterization using methods including interfacial tension, droplet size, electrical conductivity, turbidity and viscosity may provide additional information for greater predictability; 3) microemulsion drug delivery publications arise primarily from China (27%) and India (21%) suggesting additional research opportunities elsewhere. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. A pulse radiolysis study of oil/water microemulsions

    International Nuclear Information System (INIS)

    Wu, Guozhong; Katsumura, Yosuke; Chitose, Norihisa; Zuo, Zhihua

    2000-01-01

    The spectrum and yield of e aq - in quaternary benzene/water and dodecane/water microemulsions were found to be identical with those in pure water. This indicates probably the scavenging of excess electrons produced in the oil by water. To the contrary, the yield of OH radicals, determined after scavenging and conversion into (SCN) 2 -· , was proportional to water content of the microemulsion. The e aq - decay and the total yield of peroxides in aerated microemulsion were determined and the characteristics of oxidation in microemulsion was discussed. (author)

  19. Preparation and Evaluation of Emamectin Benzoate Solid Microemulsion

    OpenAIRE

    Lei Feng; Bo Cui; Dongsheng Yang; Chunxin Wang; Zhanghua Zeng; Yan Wang; Changjiao Sun; Xiang Zhao; Haixin Cui

    2016-01-01

    The solid microemulsions of emamectin benzoate with the same content of surfactants were prepared by a self-emulsifying method. Emulsifier 600# and emulsifier 700# (3/2, w/w) screened from eleven kinds of commonly used surfactants displayed great emulsifying properties. The redispersed solution of the solid microemulsion presented aqueous microemulsion characteristic. The mean particle size and polydispersity index were 10.34 ± 0.10 nm and 0.283 ± 0.013, respectively. The solid microemulsion ...

  20. Reverse Non-Equilibrium Molecular Dynamics Demonstrate That Surface Passivation Controls Thermal Transport at Semiconductor-Solvent Interfaces.

    Science.gov (United States)

    Hannah, Daniel C; Gezelter, J Daniel; Schaller, Richard D; Schatz, George C

    2015-06-23

    We examine the role played by surface structure and passivation in thermal transport at semiconductor/organic interfaces. Such interfaces dominate thermal transport in semiconductor nanomaterials owing to material dimensions much smaller than the bulk phonon mean free path. Utilizing reverse nonequilibrium molecular dynamics simulations, we calculate the interfacial thermal conductance (G) between a hexane solvent and chemically passivated wurtzite CdSe surfaces. In particular, we examine the dependence of G on the CdSe slab thickness, the particular exposed crystal facet, and the extent of surface passivation. Our results indicate a nonmonotonic dependence of G on ligand-grafting density, with interfaces generally exhibiting higher thermal conductance for increasing surface coverage up to ∼0.08 ligands/Å(2) (75-100% of a monolayer, depending on the particular exposed facet) and decreasing for still higher coverages. By analyzing orientational ordering and solvent penetration into the ligand layer, we show that a balance of competing effects is responsible for this nonmonotonic dependence. Although the various unpassivated CdSe surfaces exhibit similar G values, the crystal structure of an exposed facet nevertheless plays an important role in determining the interfacial thermal conductance of passivated surfaces, as the density of binding sites on a surface determines the ligand-grafting densities that may ultimately be achieved. We demonstrate that surface passivation can increase G relative to a bare surface by roughly 1 order of magnitude and that, for a given extent of passivation, thermal conductance can vary by up to a factor of ∼2 between different surfaces, suggesting that appropriately tailored nanostructures may direct heat flow in an anisotropic fashion for interface-limited thermal transport.

  1. Exchange coupling mechanism for magnetization reversal and thermal stability of Co nanoparticles embedded in a CoO matrix

    International Nuclear Information System (INIS)

    Givord, Dominique; Skumryev, Vassil; Nogues, Josep

    2005-01-01

    A model providing a semi-quantitative account of the magnetic behavior of Co nanoparticles embedded in a CoO matrix is presented. The results confirm that exchange coupling at the interface between ferromagnetic (FM) and antiferromagnetic (AFM) nanostructures could provide an extra source of magnetic anisotropy, leading to thermal stability of the FM nanoparticles. It is shown that perpendicular coupling between the AFM and FM moments may result in large coercivities. The energy barrier, which works against reversal is due to the AFM susceptibility anisotropy. The experimentally observed exchange bias is tentatively ascribed to pre-existing intrinsic canting of the AFM moments at the interface

  2. Effect of microemulsion component purity on the chromatographic figures of merit in chiral microemulsion electrokinetic chromatography.

    Science.gov (United States)

    Kojtari, Adeline B; Foley, Joe P

    2009-04-17

    Numerous combinations of one-, two-, and three-chiral-component microemulsions have been previously prepared in our group, using N-dodecoxycarbonylvaline (DDCV), 2-hexanol, and ethyl acetate, dibutyl tartrate, or diethyl tartrate. A few results of the various formulations investigated suggested the possible presence of minor impurities in one or more components of the microemulsion. In this study, the purity of the current lots of R- and S-surfactant were measured, as was the subsequent effect of minor impurities on the relevant chromatographic figures of merit (CFOMs) that describe a chiral separation, i.e., efficiency, enantioselectivity, retention, migration window (elution range), and resolution. Two related methods are proposed for correcting enantioselectivities measured in the presence of chiral impurities in the chiral microemulsion.

  3. Preparation and evaluation of cilnidipine microemulsion

    Science.gov (United States)

    Tandel, Hemal; Raval, Krunal; Nayani, Anil; Upadhay, Manish

    2012-01-01

    Cilnidipine, a calcium channel blocker having neuroprotective action and BCS Class II drug, hence formulating in Microemulsion will increase solubility, absorption and bioavailability. The formulation was prepared using titration method by tocotrienol, tween 20 and transcutol HP as oil, surfactant and co-surfactant and characterized for dilutability, dye solubility, assay (98.39±0.06), pH (6.6±1.5), Viscosity (98±1.0 cps) and Conductivity (0.2±0.09 μS/cm). The formulation was optimized on basis of percentage transmittance (99.269±0.23 at 700 nm), Globule size (13.31±4.3 nm) and zeta potential (–11.4±2.3 mV). Cilnidipine microemulsion was found to be stable for 3 months. PMID:23066184

  4. Preparation and evaluation of cilnidipine microemulsion

    Directory of Open Access Journals (Sweden)

    Hemal Tandel

    2012-01-01

    Full Text Available Cilnidipine, a calcium channel blocker having neuroprotective action and BCS Class II drug, hence formulating in Microemulsion will increase solubility, absorption and bioavailability. The formulation was prepared using titration method by tocotrienol, tween 20 and transcutol HP as oil, surfactant and co-surfactant and characterized for dilutability, dye solubility, assay (98.39±0.06, pH (6.6±1.5, Viscosity (98±1.0 cps and Conductivity (0.2±0.09 μS/cm. The formulation was optimized on basis of percentage transmittance (99.269±0.23 at 700 nm, Globule size (13.31±4.3 nm and zeta potential (-11.4±2.3 mV. Cilnidipine microemulsion was found to be stable for 3 months.

  5. Waste cleaning using CO2-acid microemulsion

    International Nuclear Information System (INIS)

    Park, Kwangheon; Sung, Jinhyun; Koh, Moonsung; Ju, Minsu

    2011-01-01

    Frequently we need to decontaminate radioactive wastes for volume reduction purposes. Metallic contaminants in wastes can be removed by dissolution to acid; however, this process produces a large amount of liquid acid waste. To reduce this 2ndary liquid waste, we suggest CO 2 -acid emulsion in removing metallic contaminants. Micro- and macro-emulsion of acid in liquid/supercritical CO 2 were successfully made. The formation region of microemulsion (water or acid in CO 2 ) was measured, and stability of the microemulsion was analyzed with respect to surfactant types. We applied micro- and macro-emulsion containing acid to the decontamination of radioactive metallic parts contaminated on the surface. The cleaning methods of micro- and macro-emulsion seemed better compared to the conventional acid cleaning. Moreover, these methods produce very small amount of secondary wastes. (author)

  6. Microemulsion formulation of clonixic acid: solubility enhancement and pain reduction.

    Science.gov (United States)

    Lee, Jung-Mi; Park, Kyung-Mi; Lim, Soo-Jeong; Lee, Mi-Kyung; Kim, Chong-Kook

    2002-01-01

    Clonixic acid is currently marketed as a salt form because of its poor water-solubility. However, the commercial dosage form causes severe pain after intramuscular or intravenous injection. To improve the solubility of clonixic acid and to reduce pain on injection, clonixic acid was incorporated into oil-in-water microemulsions prepared from pre-microemulsion concentrate composed of varying ratios of oil and surfactant mixture. As an oil phase for drug incorporation, up to 14% castor oil could be included in the pre-microemulsion concentrate without a significant increase in droplet size. Both drug contents and droplet size increased as the weight ratio of Tween 20 to Tween 85 decreased. Taken together, when microemulsions were prepared from pre-microemulsion concentrate composed of 5:12:18 weight ratio of castor oil:Tween 20:Tween 85, clonixic acid could be incorporated at 3.2 mg mL(-1) in the microemulsion with a droplet size of less than 120 nm. The osmotic pressure of this microemulsion was remarkably lower than the commercial formulation, irrespective of the dilution ratios. The rat paw-lick test was used to compare pain responses among formulations. The microemulsion formulation significantly reduced the number of rats licking their paws as well as the total licking time, suggesting less pain induction by the microemulsion formulation. The pharmacokinetic parameters of clonixic acid after intravenous administration of the clonixic acid microemulsion to rats were not significantly different from those of the commercial formulation, lysine clonixinate. The present study suggests that microemulsion is an alternative formulation for clonixic acid with improved characteristics.

  7. Design and Development of Repaglinide Microemulsion Gel for Transdermal Delivery.

    Science.gov (United States)

    Shinde, Ujwala A; Modani, Sheela H; Singh, Kavita H

    2018-01-01

    Microemulsion formulation of repaglinide, a BCS class II hypoglycemic agent with limited oral bioavailability, was developed considering its solubility in various oils, surfactants, and cosurfactants. The pseudo-ternary phase diagrams for microemulsion regions were constructed by water titration method at K m 1:1 and characterized for optical birefringence, percentage transmittance, pH, refractive index, globule size, zeta potential, viscosity, drug content, and thermodynamic stability. To enhance the drug permeation and residence time, the optimized microemulsions having mean globule size of 36.15 ± 9.89 nm was gelled with xanthan gum. The developed microemulsion-based gel was characterized for globule size, zeta potential, pH, and drug content. All evaluation parameters upon gelling were found to be satisfactory. Ex vivo permeability study across rat skin demonstrated higher steady-state flux (P microemulsion of repaglinide in comparison to the repaglinide microemulsion gel. At the end of 24 h, the cumulative drug permeation from microemulsion and microemulsion gel was found to be 229.19 ± 24.34 and 180.84 ± 17.40 μg/cm 2 , respectively. The microemulsion formulation showed 12.30-fold increase in flux as compared to drug suspension with highest enhancement ratio (E r ) of 12.36. Whereas microemulsion gel exhibited 10.97-fold increase in flux (with highest E r , 11.78) as compared to repaglinide (RPG) suspension. In vivo efficacy study was performed in normal Sprague-Dawley rats by using oral glucose tolerance test. Results of RPG transdermal microemulsion gel demonstrated remarkable advantage over orally administered RPG by reducing the glucose level in controlled manner. Hence, it could be a new, alternative dosage form for effective therapy of type 2 diabetes mellitus.

  8. Microstructure of microemulsion modified with ionic liquids in microemulsion electrokinetic chromatography and analysis of seven corticosteroids.

    Science.gov (United States)

    Ni, Xinjiong; Yu, Meijuan; Cao, Yuhua; Cao, Guangqun

    2013-09-01

    In this work, the influences of ionic liquid (IL) as a modifier on microemulsion microstructure and separation performance in MEEKC were investigated. Experimental results showed that synergetic effect between IL 1-butyl-3-methylimidazolium tetrafluoro-borate (BmimBF4 ) and surfactant SDS gave a decreased CMC. With increment of IL in microemulsion, negative ζ potential of the microdroplets reduced gradually. The influence of IL on the dimensions of microdroplet was complicated. At BmimBF4 less than 8 mM, IL made microemulsion droplet smaller in size. While at BmimBF4 more than 10 mM, the size increased and reached to a maximum value at 12 mM, where the microdroplets were larger than that without IL. After that, the micreodroplet size decreased again. Relative fluorescence intensity of the first vibration band of pyrene to the third one (I1 /I3 ) enhanced as IL was added to microemulsion, which indicated that this addition increased environmental polarity in the inner core of microdroplets. Prednisone, hydrocortisone, prednisolone, hydrocortisone acetate, cortisone acetate, prednisolone acetate, and triamcinolone acetonide were analyzed with MEEKC modified with IL to evaluate the separation performance. Cortisone acetate and prednisolone acetate could not be separated at all in typical microemulsion. The seven analytes could be separated by the addition of 10 mM BmimBF4 into the microemulsion system. The method has been used for analysis of corticosteroids in cosmetic samples with simple extraction; the recoveries for seven analytes were between 86 and 114%. This method provides accuracy, reproducibility, pretreatment simplicity, and could be applied to the quality control of cosmetics. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Chemical reactions in reverse micelle systems

    Science.gov (United States)

    Matson, Dean W.; Fulton, John L.; Smith, Richard D.; Consani, Keith A.

    1993-08-24

    This invention is directed to conducting chemical reactions in reverse micelle or microemulsion systems comprising a substantially discontinuous phase including a polar fluid, typically an aqueous fluid, and a microemulsion promoter, typically a surfactant, for facilitating the formation of reverse micelles in the system. The system further includes a substantially continuous phase including a non-polar or low-polarity fluid material which is a gas under standard temperature and pressure and has a critical density, and which is generally a water-insoluble fluid in a near critical or supercritical state. Thus, the microemulsion system is maintained at a pressure and temperature such that the density of the non-polar or low-polarity fluid exceeds the critical density thereof. The method of carrying out chemical reactions generally comprises forming a first reverse micelle system including an aqueous fluid including reverse micelles in a water-insoluble fluid in the supercritical state. Then, a first reactant is introduced into the first reverse micelle system, and a chemical reaction is carried out with the first reactant to form a reaction product. In general, the first reactant can be incorporated into, and the product formed in, the reverse micelles. A second reactant can also be incorporated in the first reverse micelle system which is capable of reacting with the first reactant to form a product.

  10. Dissolution of alpha-prime precipitates in thermally embrittled S2205-duplex steels during reversion-heat treatment

    Directory of Open Access Journals (Sweden)

    V. Shamanth

    2015-01-01

    Full Text Available Duplex stainless steels offer an attractive combination of strength, corrosion resistance and cost. In annealed condition duplex steels will be in thermodynamically metastable condition but when they are subjected to intermediate homologous temperature of ∼475 °C and below significant embrittlement occurs, which is one of the key material degradation properties that limits its upper service temperature in many applications. Hence the present study is aimed to study the effect of reversion heat treatment and its time on mechanical properties of the thermally embrittled steel. The results showed that 60 min reversion heat treated samples were able to recover the mechanical properties which were very close to annealed properties because when the embrittled samples were reversion heat treated at an elevated temperature of 550 °C which is above the (α + α′ miscibility gap, the ferritic phase was homogenized again. In other words, Fe-rich α and Cr-rich α′ prime precipitates which were formed during ageing become thermodynamically unstable and dissolve inside the ferritic phase.

  11. Reversible thermal transition in GrpE, the nucleotide exchange factor of the DnaK heat-shock system.

    Science.gov (United States)

    Grimshaw, J P; Jelesarov, I; Schönfeld, H J; Christen, P

    2001-03-02

    DnaK, a Hsp70 acting in concert with its co-chaperones DnaJ and GrpE, is essential for Escherichia coli to survive environmental stress, including exposure to elevated temperatures. Here we explored the influence of temperature on the structure of the individual components and the functional properties of the chaperone system. GrpE undergoes extensive but fully reversible conformational changes in the physiologically relevant temperature range (transition midpoint at approximately 48 degrees C), as observed with both circular dichroism measurements and differential scanning calorimetry, whereas no thermal transitions occur in DnaK and DnaJ between 15 degrees C and 48 degrees C. The conformational changes in GrpE appear to be important in controlling the interconversion of T-state DnaK (ATP-liganded, low affinity for polypeptide substrates) and R-state DnaK (ADP-liganded, high affinity for polypeptide substrates). The rate of the T --> R conversion of DnaK due to DnaJ-triggered ATP hydrolysis follows an Arrhenius temperature dependence. In contrast, the rate of the R --> T conversion due to GrpE-catalyzed ADP/ATP exchange increases progressively less with increasing temperature and even decreases at temperatures above approximately 40 degrees C, indicating a temperature-dependent reversible inactivation of GrpE. At heat-shock temperatures, the reversible structural changes of GrpE thus shift DnaK toward its high-affinity R state.

  12. Dermal pharmacokinetics of microemulsion formulations determined by in vivo microdialysis

    DEFF Research Database (Denmark)

    Kreilgaard, Mads

    2001-01-01

    To investigate the potential of improving dermal drug delivery of hydrophilic and lipophilic substances by formulation in microemulsion vehicles and to establish a reliable pharmacokinetic model to analyze cutaneous microdialysis data.......To investigate the potential of improving dermal drug delivery of hydrophilic and lipophilic substances by formulation in microemulsion vehicles and to establish a reliable pharmacokinetic model to analyze cutaneous microdialysis data....

  13. Interfacial properties and phase behaviour of an ionic microemulsion system

    NARCIS (Netherlands)

    Kegel, W.K.

    1993-01-01

    This thesis reports a study of a microemulsion model system composed of the ionic surfactant SDS (Sodium Dodecyl Sulfate), the cosurfactant pentanol and/or hexanol, water, salt and cyclohexane. Depending on the concentrations of the constituent parts, this system may form microemulsion phases and

  14. Design and Evaluation of Microemulsion Gel System of Nadifloxacin

    Science.gov (United States)

    Shinde, Ujwala; Pokharkar, Sharda; Modani, Sheela

    2012-01-01

    Topical microemulsion systems for the antiacne agent, nadifloxacin were designed and developed to overcome the problems associated with the cutaneous delivery due to poor water solubility. The solubility of nadifloxacin in oils, surfactants and cosurfactants was evaluated to screen the components of the microemulsion. Various surfactants and cosurfactants were screened for their ability to emulsify the selected oily phase. The pseudoternary diagrams were constructed to identify the area of microemulsion existence. The influence of km (surfactant/cosurfactant) ratio on the microemulsion existence region was determined and optimum systems were designed. The systems were assessed for drug-loading efficiency and characterised for optical birefringence, pH and refractive index, robustness to dilution, globule size, drug content and thermodynamic stability. Optimised microemulsion systems were formulated into gel form and evaluated for viscosity, spreadability, drug content, ex vivo skin permeation and antibacterial activity. The maximum solubility of nadifloxacin in the microemulsion system was found to be 0.25%. The nadifloxacin microemulsions had a small and uniform globule size (67.3-121.23 nm). The stability results revealed that all formulations showed a stable globule size and the polydispersity index under stress conditions. Incorporation of nadifloxacin in microemulsion gel increased the ex vivo skin permeation and antibacterial activity when compared to marketed cream. PMID:23439454

  15. Cytotoxicity of Gemcitabine-Loaded-Microemulsions in Breast and ...

    African Journals Online (AJOL)

    Purpose: To evaluate the antitumor activity of gemcitabine (GEM), incorporated in microemulsions with varying surfactant-to-oil (S/O) ratio, against MCF-7 breast cancer cells and HCT 116 colon cancer cells. Methods: The microemulsion formulations consisted of Tween 80, Span 20, isopropyl myristate (IPM) and aqueous ...

  16. Evolution of thermal ion transport barriers in reversed shear/ optimised shear plasmas

    International Nuclear Information System (INIS)

    Voitsekhovitch, I.; Garbet, X.; Moreau, D.; Bush, C.E.; Budny, R.V.; Gohil, P.; Kinsey, J.E.; Talyor, T.S.; Litaudon, X.

    2001-01-01

    The effects of the magnetic and ExB rotation shears on the thermal ion transport in advanced tokamak scenarios are analyzed through the predictive modelling of the evolution of internal transport barriers. Such a modelling is performed with an experimentally validated L-mode thermal diffusivity completed with a semi-empirical shear correction which is based on simple theoretical arguments from turbulence studies. A multi-machine test of the model on relevant discharges from the ITER Data Base (TFTR, DIII-D and JET) is presented. (author)

  17. Enhancement of transdermal delivery of ibuprofen using microemulsion vehicle.

    Science.gov (United States)

    Hu, Liandong; Hu, Qiaofeng; Yang, Jianxue

    2014-10-01

    The objective of this study was to find a stable microemulsion vehicle for transdermal delivery of ibuprofen to improve the skin permeability. Microemulsion was prepared using different sorts of oils, surfactants and co-surfactants. Pseudo-ternary phase diagrams were used to evaluate the microemulsion domain. The effects of oleic acid and surfactant mixture on skin permeation of ibuprofen were evaluated with excised skins. The optimum formulation F3 consisting of 6% oleic acid, 30% Cremophor RH40/Transcutol P (2:1, w/w) and 59% water phase, showed a high permeation rate of 42.98 µg/cm(2)/hr. The mean droplet size of microemulsion was about 43 nm and no skin irritation signs were observed on the skin of rabbits. These results indicated that this novel microemulsion is a useful formulation for the transdermal delivery of ibuprofen.

  18. Reversible change of birefringence sign by optical and thermal processes in an azobenzene polymethacrylate

    International Nuclear Information System (INIS)

    Rodriguez, F.J.; Sanchez, C.; Villacampa, B.; Alcala, R.; Cases, R.; Millaruelo, M.; Oriol, L.

    2005-01-01

    Birefringence (Δn) induced in an azobenzene polymethacrylate by combination of biphotonic and thermotropic processes has subsequently been changed in sign by room temperature illumination with linearly polarized blue light. The sign of Δn can be reversed again, by simply heating up the film to 100 deg. C. This change of Δn between positive and negative values can be repeated several times. Besides, by appropriate choice of film thickness and blue light irradiation conditions the same absolute value for positive and negative Δn values can be obtained

  19. Synthesis of tin monosulfide (SnS) nanoparticles using surfactant free microemulsion (SFME) with the single microemulsion scheme

    Science.gov (United States)

    Tarkas, Hemant S.; Marathe, Deepak M.; Mahajan, Mrunal S.; Muntaser, Faisal; Patil, Mahendra B.; Tak, Swapnil R.; Sali, Jaydeep V.

    2017-02-01

    Synthesis of monomorphic, SnS nanoparticles without using a capping agent is a difficult task with chemical route of synthesis. This paper reports on synthesis of tin monosulfide (SnS) nanopartilces with dimension in the quantum-dot regime using surfactant free microemulsion with single microemulsion scheme. This has been achieved by reaction in microreactors in the CME (C: chlorobenzene, M: methanol and E: ethylene glycol) microemulsion system. This is an easy and controllable chemical route for synthesis of SnS nanoparticles. Nanoparticle diameter showed prominent dependence on microemulsion concentration and marginal dependence on microemulsion temperature in the temperature range studied. The SnS nanoparticles formed with this method form stable dispersion in Tolune.

  20. Application of a reversible chemical reaction system to solar thermal power plants

    Science.gov (United States)

    Hanseth, E. J.; Won, Y. S.; Seibowitz, L. P.

    1980-01-01

    Three distributed dish solar thermal power systems using various applications of SO2/SO3 chemical energy storage and transport technology were comparatively assessed. Each system features various roles for the chemical system: (1) energy storage only, (2) energy transport, or (3) energy transport and storage. These three systems were also compared with the dish-Stirling, using electrical transport and battery storage, and the central receiver Rankine system, with thermal storage, to determine the relative merit of plants employing a thermochemical system. As an assessment criterion, the busbar energy costs were compared. Separate but comparable solar energy cost computer codes were used for distributed receiver and central receiver systems. Calculations were performed for capacity factors ranging from 0.4 to 0.8. The results indicate that SO2/SO3 technology has the potential to be more cost effective in transporting the collected energy than in storing the energy for the storage capacity range studied (2-15 hours)

  1. Radiative thermal emission from silicon nanoparticles: a reversed story from quantum to classical theory

    International Nuclear Information System (INIS)

    Roura, P.; Costa, J.

    2002-01-01

    Among the rush of papers published after the discovery of visible luminescence in porous silicon, a number of them claimed that an extraordinary behaviour had been found. However, after five years of struggling with increasingly sophisticated but not completely successful models, it was finally demonstrated that it was simply thermal radiation. Here, we calculate thermal radiation emitted by silicon nanoparticles when irradiated in vacuum with a laser beam. If one interprets this radiation as being photoluminescence, its properties appear extraordinary: non-exponential excitation and decay transients and a supralinear dependence on laser power. Within the (quantum) theory of photoluminescence, this behaviour can be interpreted as arising from a non-usual excitation mechanism known as multiphoton excitation. Although this erroneous interpretation has, to some extent, a predictive power, it is unable to give a sound explanation for the quenching of radiation when particles are not irradiated in vacuum but inside a gas. The real story of this error is presented both to achieve a deeper understanding of the radiative thermal emission of nanoparticles and as a matter of reflection on scientific activity. (author)

  2. Reversible thermal fusing model of carbon black current-limiting thermistors

    International Nuclear Information System (INIS)

    Martin, James E.; Heaney, Michael B.

    2000-01-01

    Composites of carbon black particles in polyethylene exhibit an unusually rapid increase in resistivity as the applied electric field is increased, making this material commercially useful as current-limiting thermistors, also known as automatically resettable fuses. In this application the composite is in series with the circuit it is protecting: at low applied voltages the circuit is the load, but at high applied voltages the composite becomes the load, limiting the current to the circuit. We present a simple model of this behavior in terms of a network of nonlinear resistors. Each resistor has a resistance that depends explicitly and reversibly on its instantaneous power dissipation. This model predicts that in the soft fusing, or current-limiting, regime, where the current through the composite decreases with increasing voltage, a platelike dissipation instability develops normal to the applied field, in agreement with experimental observations, which is solely due to fluctuations in the microstructure

  3. PREPARATION AND PROPERTIES OF COMPOUND ARNEBIAE RADIX MICROEMULSION GEL.

    Science.gov (United States)

    Chen, Jing; He, Yanping; Gao, Ting; Zhang, Licheng; Zhao, Yuna

    2017-01-01

    Compound Arnebiae radix oil has been clinically applied to treat burns and scalds for a long time. However, it is unstable and inconvenient to use. The aim of this study was to prepare a compound Arnebiae radix microemulsion gel for transdermal delivery system and evaluate its characteristics. Based on the solubility of Shikonin, the active component of Arnebiae radix and the results of phase studies, adequate ratio of each component in microemulsion was determined. The optimized microemulsion gel was prepared using Carbomer 940. The gels were characterized in terms of appearance, preliminary stability test and the content of Shikonin in the compound Arnebiae radix microemulsion gel with HPLC analysis. The optimized conditions for preparing microemulsion were Tween-80, glycerin, isopropyl myristate (IPM) with the ratio of 6:3:2. The optimal microemulsion gel was obtained with Carbomer 940 (1.0%). The prepared compound Arnebiae radix microemulsion gel showed good stability over time. It is more convenience in application than the previous used formulations.

  4. Evaluation of Ocular Irritation and Bioavailability of Voriconazole Loaded Microemulsion.

    Science.gov (United States)

    Kumar, Rakesh; Sinha, Vivek Ranjan

    2017-01-01

    Voriconazole (VCZ), a second-generation antifungal with excellent attributes like, broad-spectrum activity, targeted delivery, and tolerability. VCZ loaded microemulsion could be an effective strategy for efficient ocular delivery of the drug. To perform corneal irritation studies and in vivo delivery of VCZ microemulsion to establish its potential as an efficient ocular delivery system. Ocular irritancy was performed by HETCAM (Hen's Egg Test Chorio Allantoic Membrane) assay, corneal histopathology and Draize test. Ex vivo and in vivo studies were performed to determine permeation efficiency of VCZ microemulsion. The irritation studies suggested the non-irritant nature of the microemulsion. The ex vivo studies performed on excised cornea displayed significant enhancement in drug permeation/penetration from microemulsion in contrast to the drug suspension. Further, the in vivo study confirmed the higher availability of VCZ (from microemulsion) in aqueous humor with minimal nasolacrimal drainage (lower plasma drug content) when compared with the drug suspension. The non-irritant nature and high corneal permeation of VCZ encourages the role of microemulsion as a potential ocular delivery system. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  5. Evaluation of nicotinamide microemulsion on the skin penetration enhancement.

    Science.gov (United States)

    Boonme, Prapaporn; Boonthongchuay, Chalida; Wongpoowarak, Wibul; Amnuaikit, Thanaporn

    2016-01-01

    This study purposed to evaluate a microemulsion containing nicotinamide for its characteristics, stability, and skin penetration and retention comparing with a solution of nicotinamide in 2:1 mixture of water and isopropyl alcohol (IPA). The microemulsion system was composed of 1:1 mixture of Span80 and Tween80 as a surfactant mixture, isopropyl palmitate (IPP) as an oil phase, and 2:1 mixture of water and IPA as an aqueous phase. Nicotinamide microemulsion was prepared by dissolving the active in the aqueous phase before simply mixing with the other components. It was determined for its characteristics and stability under various conditions. The skin penetration and retention studies of nicotinamide microemulsion and solution were performed by modified Franz diffusion cells, using newborn pig skin as the membrane. The results showed that nicotinamide microemulsion could be obtained as clear yellowish liquid, was water-in-oil (w/o) type, possessed Newtonian flow, and exhibited physicochemical stability when kept at 4 °C and room temperature (≈30 ± 2 °C) during 3 months. From the skin penetration data, the microemulsion could enhance the skin penetration of nicotinamide comparing with the solution. Additionally, nicotinamide microemulsion could provide much higher amount of skin retention than that of skin penetration, resulting in suitability for a cosmeceutical product.

  6. Microemulsion systems studied by positron annihilation techniques. II

    International Nuclear Information System (INIS)

    Lopez, R.; Olea, O.; Fucugauchi, L.A.

    1982-01-01

    The positron annihilation technique was applied to assess the effect of the double bond of the surfactant molecule on the microemulsion formation mechanism by replacing sodium stearate by sodium oleate in surfactant-cosurfactant-solvent-water systems. Diameters of microemulsions were measured by dynamic laser light scattering, and the obtained values concur with the present positron annihilation data. Structures of these microemulsions have been assessed by considering the available conformation and shapes of the surfactant-cosurfactant-solvent-assemblies. Volumes of the same aggregates have been calculated by taking into consideration the packing constraint imposed upon kink formation. (Auth.)

  7. Size Controlled Synthesis of Starch Nanoparticles by a Microemulsion Method

    Directory of Open Access Journals (Sweden)

    Suk Fun Chin

    2014-01-01

    Full Text Available Controllable particles sizes of starch nanoparticles were synthesized via a precipitation in water-in-oil microemulsion approach. Microemulsion method offers the advantages of ultralow interfacial tension, large interfacial area, and being thermodynamically stable and affords monodispersed nanoparticles. The synthesis parameters such as stirring rates, ratios of oil/cosurfactant, oil phases, cosurfactants, and ratios of water/oil were found to affect the mean particle size of starch nanoparticles. Starch nanoparticles with mean particles sizes of 109 nm were synthesized by direct nanoprecipitation method, whereas by using precipitation in microemulsion approach, starch nanoparticles with smaller mean particles sizes of 83 nm were obtained.

  8. Effect of microemulsions on cell viability of human dermal fibroblasts

    Science.gov (United States)

    Li, Juyi; Mironava, Tatsiana; Simon, Marcia; Rafailovich, Miriam; Garti, Nissim

    Microemulsions are optically clear, thermostable and isotropic mixture consisting of water, oil and surfactants. Their advantages of ease preparation, spontaneous formation, long-term stability and enhanced solubility of bioactive materials make them great potentials as vehicles in food and pharmaceutical applications. In this study, comparative in vitro cytotoxicity tests were performed to select a best formulation of microemulsion with the least toxicity for human dermal fibroblasts. Three different kinds of oils and six different kinds of surfactants were used to form microemulsions by different ratios. The effect of oil type and surfactant type as well as their proportions on cell proliferation and viability were tested.

  9. Frozen Microemulsions for MAPLE Immobilization of Lipase

    Directory of Open Access Journals (Sweden)

    Valeria Califano

    2017-12-01

    Full Text Available Candida rugosa lipase (CRL was deposited by matrix assisted pulsed laser evaporation (MAPLE in order to immobilize the enzyme with a preserved native conformation, which ensures its catalytic functionality. For this purpose, the composition of the MAPLE target was optimized by adding the oil phase pentane to a water solution of the amino acid 3-(3,4-dihydroxyphenyl-2-methyl-l-alanine (m-DOPA, giving a target formed by a frozen water-lipase-pentane microemulsion. Fourier transform infrared (FTIR spectroscopy and atomic force microscopy (AFM were used to investigate the structure of MAPLE deposited lipase films. FTIR deconvolution of amide I band indicated a reduction of unfolding and aggregation, i.e., a better preserved lipase secondary structure in the sample deposited from the frozen microemulsion target. AFM images highlighted the absence of big aggregates on the surface of the sample. The functionality of the immobilized enzyme to promote transesterification was determined by thin layer chromatography, resulting in a modified specificity.

  10. Solubilization of paraffinic deposits for microemulsions

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, Erika A.S.; Soares, Ranieri G.F.; Nascimento, Roseane E.S.; Dantas Neto, Afonso A.; Barros Neto, Eduardo L. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil)

    2008-07-01

    The oil company has been intensifying its efforts to find more efficient solutions for the problems related to the paraffin in wells and transport lines. When applied in the flow lines, the solvents dissolve the paraffin and they must be used hot, since the temperature increases the solubility of the wax and, consequently, its removal rate. The microemulsions appear as an alternative capable of acting in the solubilization and in the inhibition of the formation of deposits due to its great interfacial area, low superficial tension and high capacity of solubilization. They present some advantages in relation to the methods of use of chemical products due to its flexibility of composition in which they can be used, presenting low toxicity and inflammability, without any loss of its capacity of solubilization. The use of oil-in-water microemulsion aims to solubilized paraffin in the disperse phase, where one can find the apolar part of the molecule of the surfactant and the also apolar chain of paraffin, occurring, therefore the 'encapsulation' of the crystal, prohibiting the growth of the chain due to the affinity of paraffin and oil. In this in case, it is possible to transport the inserted paraffin in direct micelles, reducing the precipitation and optimizing the transport. (author)

  11. Investigating the evolution of the phase behavior of AOT-based w/o microemulsions in dodecane as a function of droplet volume fraction.

    Science.gov (United States)

    Ganguly, R; Choudhury, N

    2012-04-15

    AOT-based water in oil (w/o) microemulsions are one of the most extensively studied reverse micellar systems because of their rich phase behavior and their ability to form in the absence of any co-surfactant. The aggregation characteristics and interaction of the microemulsion droplets in these systems are known to be governed by AOT-oil compatibility and water to AOT molar ratio (w). In this manuscript by using Dynamic Light Scattering (DLS) and viscometry techniques, we show that droplet volume fraction too plays an important role in shaping the phase behavior of these microemulsions in dodecane. The phase separation characteristics and the evolution of the viscosity and the hydrodynamic radius of the microemulsion droplets on approaching the cloud points have thus been found to undergo complete transformation as one goes from low to high droplet volume fraction even at a fixed 'w'. Modeling of the DLS data attributes this to the weakening of inter droplet attractive interaction caused by the growing dominance of the excluded volume effect with increase in droplet volume fraction. In the literature, the inter droplet attractive interaction driven phase separation in these microemulsions is explained based on gas-liquid type phase transition, conceptualized in the framework of Baxter adhesive hard sphere theory. The modeling of our viscosity data, however, does not support such proposition as the characteristic stickiness parameter (τ(-1)) of the microemulsion droplets in this system remains much lower than the critical value (τ(c)(-1)≈10.25) required to enforce such phase transition. Copyright © 2012 Elsevier Inc. All rights reserved.

  12. Preparation and Evaluation of Emamectin Benzoate Solid Microemulsion

    Directory of Open Access Journals (Sweden)

    Lei Feng

    2016-01-01

    Full Text Available The solid microemulsions of emamectin benzoate with the same content of surfactants were prepared by a self-emulsifying method. Emulsifier 600# and emulsifier 700# (3/2, w/w screened from eleven kinds of commonly used surfactants displayed great emulsifying properties. The redispersed solution of the solid microemulsion presented aqueous microemulsion characteristic. The mean particle size and polydispersity index were 10.34 ± 0.10 nm and 0.283 ± 0.013, respectively. The solid microemulsion showed excellent storage stability and the bioassay compared with water dispersible granules against diamondback moths provided a proof of its improved biological activities. This formulation could significantly reduce surfactants and is perspective in plant protection for improving bioavailability and environmental friendliness.

  13. Nanoscopic dynamics of bicontinous microemulsions: effect of membrane associated protein.

    Science.gov (United States)

    Sharma, V K; Hayes, Douglas G; Urban, Volker S; O'Neill, Hugh M; Tyagi, M; Mamontov, E

    2017-07-19

    Bicontinous microemulsions (BμE) generally consist of nanodomains formed by surfactant in a mixture of water and oil at nearly equal proportions and are potential candidates for the solubilization and purification of membrane proteins. Here we present the first time report of nanoscopic dynamics of surfactant monolayers within BμEs formed by the anionic surfactant sodium dodecyl sulfate (SDS) measured on the nanosecond to picosecond time scale using quasielastic neutron scattering (QENS). BμEs investigated herein consisted of middle phases isolated from Winsor-III microemulsion systems that were formed by mixing aqueous and oil solutions under optimal conditions. QENS data indicates that surfactants undergo two distinct motions, namely (i) lateral motion along the surface of the oil nanodomains and (ii) localized internal motion. Lateral motion can be described using a continuous diffusion model, from which the lateral diffusion coefficient is obtained. Internal motion of surfactant is described using a model which assumes that a fraction of the surfactants' hydrogens undergoes localized translational diffusion that could be considered confined within a spherical volume. The effect of cytochrome c, an archetypal membrane-associated protein known to strongly partition near the surfactant head groups in BμEs (a trend supported by small-angle X-ray scattering [SAXS] analysis), on the dynamics of BμE has also been investigated. QENS results demonstrated that cytochrome c significantly hindered both the lateral and the internal motions of surfactant. The lateral motion was more strongly affected: a reduction of the lateral diffusion coefficient by 33% was measured. This change is mainly attributable to the strong association of cytochrome c with oppositely charged SDS. In contrast, analysis of SAXS data suggested that thermal fluctuations (for a longer length and slower time scale compared to QENS) were increased upon incorporation of cytochrome c. This study

  14. Transdermal delivery of paeonol using cubic gel and microemulsion gel

    Science.gov (United States)

    Luo, Maofu; Shen, Qi; Chen, Jinjin

    2011-01-01

    Background The aim of this study was to develop new systems for transdermal delivery of paeonol, in particular microemulsion gel and cubic gel formulations. Methods Various microemulsion vehicles were prepared using isopropyl myristate as an oil phase, polyoxyethylated castor oil (Cremophor® EL) as a surfactant, and polyethylene glycol 400 as a cosurfactant. In the optimum microemulsion gel formulation, carbomer 940 was selected as the gel matrix, and consisted of 1% paeonol, 4% isopropyl myristate, 28% Cremophor EL/polyethylene glycol 400 (1:1), and 67% water. The cubic gel was prepared containing 3% paeonol, 30% water, and 67% glyceryl monooleate. Results A skin permeability test using excised rat skins indicated that both the cubic gel and microemulsion gel formulations had higher permeability than did the paeonol solution. An in vivo pharmacokinetic study done in rats showed that the relative bioavailability of the cubic gel and microemulsion gel was enhanced by about 1.51-fold and 1.28-fold, respectively, compared with orally administered paeonol suspension. Conclusion Both the cubic gel and microemulsion gel formulations are promising delivery systems to enhance the skin permeability of paeonol, in particular the cubic gel. PMID:21904450

  15. Physicochemical, in vitro and in vivo evaluation of flurbiprofen microemulsion.

    Science.gov (United States)

    Naeem, Muhammad; Ur Rahman, Nisar; Tavares, Guilherme D; Barbosa, Sávio F; Chacra, Nádia B; Löbenberg, Raimar; Sarfraz, Muhammad K

    2015-09-01

    Flurbiprofen, a potent nonsteroidal anti-inflammatory drug, is widely used for relief of pain in patients suffering from rheumatic diseases, migraine, sore throat and primary dysmenorrheal. However, this drug has many gastrointestinal side effects produced by its oral administration, such as gastric bleeding and peptic ulcer. These effects were responsible for non-compliance among patients, which ultimately results in treatment failure. The physicochemical properties of flurbiprofen, make it a suitable candidate for transdermal drug delivery, which can overcome the drawbacks of oral administration. In this sense, microemulsions have been proved to increase the cutaneous absorption of lipophilic drugs when compared to conventional drug delivery systems. The purpose of this study was to formulate and characterize gel based microemulsions, for topical delivery of flurbiprofen. Different gel bases, containing microemulsion and hydro-alcoholic solution of flurbiprofen, were developed and compared. In vitro study showed that gels containing microemulsion had a higher permeation rate than those containing hydro-alcoholic solutions. Additionally, formulation of Carbopol-I (microemulsion) showed higher percent of inhibition of inflammation than others bases. Further, skin irritation study demonstrated that Carbopol-I was none irritating. Flurbiprofen microemulsion incorporated on Carbopol-I showed physicochemical, in vitro and in vivo characteristics suitable for the development of alternative transdermal delivery formulation.

  16. Physicochemical, in vitro and in vivo evaluation of flurbiprofen microemulsion

    Directory of Open Access Journals (Sweden)

    MUHAMMAD NAEEM

    2015-09-01

    Full Text Available ABSTRACTFlurbiprofen, a potent nonsteroidal anti-inflammatory drug, is widely used for relief of pain in patients suffering from rheumatic diseases, migraine, sore throat and primary dysmenorrheal. However, this drug has many gastrointestinal side effects produced by its oral administration, such as gastric bleeding and peptic ulcer. These effects were responsible for non-compliance among patients, which ultimately results in treatment failure. The physicochemical properties of flurbiprofen, make it a suitable candidate for transdermal drug delivery, which can overcome the drawbacks of oral administration. In this sense, microemulsions have been proved to increase the cutaneous absorption of lipophilic drugs when compared to conventional drug delivery systems. The purpose of this study was to formulate and characterize gel based microemulsions, for topical delivery of flurbiprofen. Different gel bases, containing microemulsion and hydro-alcoholic solution of flurbiprofen, were developed and compared. In vitro study showed that gels containing microemulsion had a higher permeation rate than those containing hydro-alcoholic solutions. Additionally, formulation of Carbopol-I (microemulsion showed higher percent of inhibition of inflammation than others bases. Further, skin irritation study demonstrated that Carbopol-I was none irritating. Flurbiprofen microemulsion incorporated on Carbopol-I showed physicochemical, in vitro and in vivo characteristics suitable for the development of alternative transdermal delivery formulation.

  17. Photopyroelectric Calorimetry Investigations of 8CB Liquid Crystal-Microemulsion System

    Science.gov (United States)

    Paoloni, S.; Zammit, U.; Mercuri, F.

    2018-02-01

    In this work, the photopyroelectric technique has been used to investigate the phase transitions in a liquid crystal microemulsion by combining the simultaneous high temperature resolution thermal diffusivity measurements and optical polarization microscopy observations. It has been found that, during the conversion from the isotropic phase into the nematic one, the micelles are expelled from the nematic domains and remain confined in islands of isotropic material which survive down to the smectic temperature range. A hysteresis in the thermal diffusivity profiles between heating and cooling run over the isotropic-nematic transition temperature range has been observed which has been ascribed to the different micelles distribution into the sample volume during cooling and heating runs. Finally, the almost bulk-like behavior of the thermal diffusivity over the nematic-smectic phase transition confirms that a significant fraction of the micelles are expelled during the nucleation of the nematic phase.

  18. Topical Nano and Microemulsions for Skin Delivery

    Directory of Open Access Journals (Sweden)

    Christofori M. R. R. Nastiti

    2017-09-01

    Full Text Available Nanosystems such as microemulsions (ME and nanoemulsions (NE offer considerable opportunities for targeted drug delivery to and via the skin. ME and NE are stable colloidal systems composed of oil and water, stabilised by a mixture of surfactants and cosurfactants, that have received particular interest as topical skin delivery systems. There is considerable scope to manipulate the formulation components and characteristics to achieve optimal bioavailability and minimal skin irritancy. This includes the incorporation of established chemical penetration enhancers to fluidize the stratum corneum lipid bilayers, thus reducing the primary skin barrier and increasing permeation. This review discusses nanosystems with utility in skin delivery and focuses on the composition and characterization of ME and NE for topical and transdermal delivery. The mechanism of skin delivery across the stratum corneum and via hair follicles is reviewed with particular focus on the influence of formulation.

  19. Salt effects in surfactant-free microemulsions

    Science.gov (United States)

    Schöttl, Sebastian; Horinek, Dominik

    2018-06-01

    The weakly associated micellar aggregates found in the so-called "pre-ouzo region" of the surfactant-free microemulsion water/ethanol/1-octanol are sensitive to changes in the system composition and also to the presence of additives like salt. In this work, we study the influence of two salts, sodium iodide and lithium chloride, on aggregates in water/ethanol/1-octanol by molecular dynamics simulations. In both cases, ethanol concentration in the nonpolar phase and at the interface is increased due to a salting out effect on ethanol in the aqueous pseudo-phase. In addition, minor charging of the interface as a consequence of differential adsorption of anions and cations occurs. However, this charge separation is overall weakened by the erratic surface of octanol aggregates, where polar hydroxyl groups and hydrophobic patches are both present. Furthermore, ethanol at the interface shields hydrophobic patches and reduces the preferential adsorption of iodide and lithium.

  20. Polyisoprene Nanoparticles Prepared by Polymerization in Microemulsion

    Directory of Open Access Journals (Sweden)

    Y. Apolinar

    2010-01-01

    Full Text Available Batch polymerization of isoprene was carried out at 25∘C in a normal microemulsion stabilized with sodium dodecyl sulfate and initiated with the redox couple tert-butyl hydroperoxide/tetraethylene-pentamine. Characterization by transmission electronic microscopy showed that polyisoprene nanoparticles with number-average diameter close to 20 nm were obtained. The low molecular weights obtained, as determined by gel permeation chromatography, were probably due to chain scission as inferred from the oxidative ambient at which polymerization was carried out. Microstructure calculated from infrared spectroscopy data indicates that the obtained polyisoprene contains around 80% total 1,4 units, which is in accordance with its glass transition temperature (-60.8∘C determined by differential scanning calorimetry.

  1. Poly(dodecyl methacrylate) as solvent of paraffins for phase change materials and thermally reversible light scattering films.

    Science.gov (United States)

    Puig, Julieta; Williams, Roberto J J; Hoppe, Cristina E

    2013-09-25

    Paraffins are typical organic phase change materials (PCM) used for latent heat storage. For practical applications they must be encapsulated to prevent leakage or agglomeration during fusion. In this study it is shown that eicosane (C20H42 = C20) in the melted state could be dissolved in the hydrophobic domains of poly(dodecyl methacrylate) (PDMA) up to concentrations of 30 wt %, avoiding the need of encapsulation. For a 30 wt % solution, the heat of phase change was close to 69 J/g, a reasonable value for its use as a PCM. The fully converted solution remained transparent at 80 °C with no evidence of phase separation but became opaque by cooling as a consequence of paraffin crystallization. Heating above the melting temperature regenerated a transparent material. A high contrast ratio and abrupt transition between opaque and transparent states was observed for the 30 wt % blends, with a transparent state at 35 °C and an opaque state at 23 °C. This behavior was completely reproducible during consecutive heating/cooling cycles, indicating the possible use of this material as a thermally reversible light scattering (TRLS) film.

  2. Les microémulsions Microemulsions

    Directory of Open Access Journals (Sweden)

    Bavière M.

    2006-11-01

    Full Text Available Depuis une quinzaine d'années, les microémulsions intéressent l'industrie pétrolière, en effet, leur miscibilité apparente avec l'eau et les hydrocarbures, jointe à des propriétés originales de stabilité et de viscosité, en fait des fluides de drainage de l'huile, même résiduelle, extrêmement efficaces, leur emploi est également recommandé pour la stimulation des puits d'injection ou de production. La présente étude bibliographique s'applique à situer d'abord les microémulsions dans le contexte des solutions micellaires, puis à présenter les théories qui expliquent leur formation, leur structure et leurs propriétés, et enfin à décrire le procédé de récupération du pétrole tel qu'il a été étudié au laboratoire, et mis en oeuvre sur champ pendant la dernière décennie. In the last fifteen years, the petroleum industry has become interested in microemulsions. Their apparent miscibility with water and hydrocarbons as well as their original properties of stability and viscosity make them extremely effective oil drainage fluids, even for residual oil. They are also recommended for stimulating injection or production wells. This bibliographic survey attempts first to situate microemulsions with in the context of micellar solutions and then to review theories explaining their formation, structure and properties. lastly, a description is given of an oil recovery process that has been laboratory researched and applied in the field during the last decade.

  3. Development of a novel microemulsion for oral absorption enhancement of all-trans retinoic acid.

    Science.gov (United States)

    Subongkot, Thirapit; Ngawhirunpat, Tanasait

    2017-01-01

    This study was aimed to develop a novel microemulsion that contained oleth-5 as a surfactant to enhance the oral absorption of all-trans retinoic acid (ATRA). The prepared microemulsion was evaluated for its particle size, shape, zeta potential, in vitro release, in vitro intestinal absorption, intestinal membrane cytotoxicity and stability. The obtained microemulsion was spherical in shape with a particle size of microemulsion was best fit with the zero-order model. This microemulsion significantly improved the intestinal absorption of ATRA. Confocal laser scanning microscopy analysis using a fluorescent dye-loaded microemulsion also confirmed the intestinal absorption result. The intestinal membrane cytotoxicity of the ATRA-loaded microemulsion did not differ from an edible oil (fish oil). Stability testing showed that the ATRA-loaded microemulsion was more stable at 25°C than 40°C.

  4. Characterization of nanoparticles of lidocaine in w/o microemulsions using small-angle neutron scattering and dynamic light scattering

    International Nuclear Information System (INIS)

    Shukla, A.; Kiselev, M.A.; Hoell, A.; Neubert, R.H.H.

    2004-01-01

    Microemulsions (MEs) are of special interest because a variety of reactants can be introduced into the nanometer-sized aqueous domains, leading to materials with controlled size and shape. In the past few years, significant research has been conducted in the reverse ME-mediated synthesis of organic nanoparticles. In this study, a w/o ME medium was employed for the synthesis of lidocaine by direct precipitation in w/o microemulsion systems: water/isopropylpalmitat/Tween80/Span80. The particle size as well as the location of nanoparticles in the ME droplet were characterized by means of dynamic light scattering (DLS) and small angle neutron scattering (SANS). It is observed that lidocaine precipitated in the aqueous cores because of its insolubility in water. Hydrodynamic radius and gyration radius of microemulsion droplets were estimated as ∼15 nm and ∼4.50 nm from DLS and SANS respectively. Furthermore, different size parameters obtained by DLS and SANS experiments were compared. (author)

  5. Characterization of nanoparticles of lidocaine in w/o microemulsions using small-angle neutron scattering and dynamic light scattering

    Science.gov (United States)

    Shukla, A.; Kiselev, M. A.; Hoell, A.; Neubert, R. H. H.

    2004-08-01

    Microemulsions (MEs) are of special interest because a variety of Reactants can be introduced into the nanometer-sized aqueous domains, leading to materials with controlled size and shape [1,2]. In the past few years, significant research has been conducted in the reverse ME-mediated synthesis of organic nanoparticles [3,4]. In this study, a w/o ME medium was employed for the synthesis of lidocaine by direct precipitation in w/o microemulsion systems: water/isopropylpalmitat/Tween80/Span80. The particle size as well as the location of nanoparticles in the ME droplet were characterized by means of dynamic light scattering (DLS) and small angle neutron scattering (SANS). It is observed that lidocaine precipitated in the aqueous cores because of its insolubility in water. Hydrodynamic radius and gyration radius of microemulsion droplets were estimated as ~15 nm and ~4.50 nm from DLS and SANS respectively. Furthermore, different size parameters obtained by DLS and SANS experiments were compared

  6. Development and characterization of morin hydrate loaded microemulsion for the management of Alzheimer's disease.

    Science.gov (United States)

    Sharma, Dheeraj; Singh, Manpreet; Kumar, Punnet; Vikram, Vir; Mishra, Neeraj

    2017-12-01

    The aim of this study is to prepare and characterize intranasal delivery of morin hydrate loaded microemulsion for the management of Alzheimer's diseases. After intranasal delivery, brain and blood drug concentrations were found to be higher for optimized morin hydrate loaded microemulsion as compared to plain morin hydrate. Significant (P microemulsion as compared to sham control group. Daily chronic treatment with morin loaded microemulsion till the 21st day significantly increased the memory in wistar rats with STZ-induced dementia.

  7. Design and development of microemulsion drug delivery system of acyclovir for improvement of oral bioavailability

    OpenAIRE

    Ghosh, Pradip Kumar; Majithiya, Rita J.; Umrethia, Manish L.; Murthy, Rayasa S. R.

    2006-01-01

    The main purpose of this work was to develop an oral microemulsion formulation for enhancing the bioavailability of acyclovir. A Labrafac-based microemulsion formulation with Labrasol as surfactant and Plurol Oleique as cosurfactant was developed for oral delivery of acyclovir. Phase behavior and solubilization capacity of the microemulsion system were characterized, and in vivo oral absorption of acyclovir from the microemulsion was investigated in rats. A single isotropic region, which was ...

  8. Two-photon fluorescent polysiloxane-based films with thermally responsive self switching properties achieved by a unique reversible spirocyclization mechanism.

    Science.gov (United States)

    Zuo, Yujing; Yang, Tingxin; Zhang, Yu; Gou, Zhiming; Tian, Minggang; Kong, Xiuqi; Lin, Weiying

    2018-03-14

    Responsiveness and reversibility are present in nature, and are ubiquitous in biological systems. The realization of reversibility and responsiveness is of great importance in the development of properties and the design of new materials. However, two-photon fluorescent thermal-responsive materials have not been reported to date. Herein, we engineered thermally responsive polysiloxane materials ( Dns-non ) that exhibited unique two-photon luminescence, and this is the first report about thermally responsive luminescent materials with two-photon fluorescence. The fluorescence of Dns-non could switch from the "on" to "off" state through a facile heating and cooling process, which could be observed by the naked eye. Monitoring the temperature of the CPU in situ was achieved by easily coating D1-non onto the CPU surface, which verified the potential application in devices of Dns-non . A unique alkaline tuned reversible transition mechanism of rhodamine-B from its spirocyclic to its ring-open state was proposed. Furthermore, Dns-non appeared to be a useful cell adhesive for the culture of cells on the surface. We believe that the constructed thermally responsive silicon films which have promising utilization as a new type of functional fluorescent material, may show broad applications in materials chemistry or bioscience.

  9. Epoxy-Based Organogels for Thermally Reversible Light Scattering Films and Form-Stable Phase Change Materials.

    Science.gov (United States)

    Puig, Julieta; Dell' Erba, Ignacio E; Schroeder, Walter F; Hoppe, Cristina E; Williams, Roberto J J

    2017-03-29

    Alkyl chains of β-hydroxyesters synthesized by the capping of terminal epoxy groups of diglycidylether of bisphenol A (DGEBA) with palmitic (C16), stearic (C18), or behenic (C22) fatty acids self-assemble forming a crystalline phase. Above a particular concentration solutions of these esters in a variety of solvents led to supramolecular (physical) gels below the crystallization temperature of alkyl chains. A form-stable phase change material (FS-PCM) was obtained by blending the ester derived from behenic acid with eicosane. A blend containing 20 wt % ester was stable as a gel up to 53 °C and exhibited a heat storage capacity of 161 J/g, absorbed during the melting of eicosane at 37 °C. Thermally reversible light scattering (TRLS) films were obtained by visible-light photopolymerization of poly(ethylene glycol) dimethacrylate-ester blends (50 wt %) in the gel state at room temperature. The reaction was very fast and not inhibited by oxygen. TRLS films consisted of a cross-linked methacrylic network interpenetrated by the supramolecular network formed by the esters. Above the melting temperature of crystallites formed by alkyl chains, the film was transparent due to the matching between refractive indices of the methacrylic network and the amorphous ester. Below the crystallization temperature, the film was opaque because of light dispersion produced by the organic crystallites uniformly dispersed in the material. Of high significance for application was the fact that the contrast ratio did not depend on heating and cooling rates.

  10. Oral microemulsions of paclitaxel: in situ and pharmacokinetic studies.

    Science.gov (United States)

    Nornoo, Adwoa O; Zheng, Haian; Lopes, Luciana B; Johnson-Restrepo, Boris; Kannan, Kurunthachalam; Reed, Rachel

    2009-02-01

    The overall goal of this study was to develop cremophor-free oral microemulsions of paclitaxel (PAC) to enhance its permeability and oral absorption. The mechanism of this enhancement, as well as characteristics of the microemulsions relevant to the increase in permeability and absorption of the low solubility, low permeability PAC was investigated. Phase diagrams were used to determine the macroscopic phase behavior of the microemulsions and to compare the efficiency of different surfactant-oil mixtures to incorporate water. The microemulsion region on the phase diagrams utilizing surfactant-myvacet oil combinations was in decreasing order: lecithin: butanol: myvacet oil (LBM, 48.5%)>centromix CPS: 1-butanol: myvacet oil (CPS, 45.15%)>capmul MCM: polysorbate 80: myvacet oil (CPM, 27.6%)>capryol 90: polysorbate 80: myvacet oil (CP-P80, 23.9%)>capmul: myvacet oil (CM, 20%). Oil-in-water (o/w) microemulsions had larger droplet sizes (687-1010 nm) than the water-in-oil (w/o) microemulsions (272-363 nm) when measured using a Zetasizer nano series particle size analyzer. Utilizing nuclear magnetic resonance spectroscopy (NMR), the self-diffusion coefficient (D) of PAC in CM, LBM and CPM containing 10% of deuterium oxide (D(2)O) was 2.24x10(-11), 1.97x10(-11) and 0.51x10(-11) m(2)/s, respectively. These values indicate the faster molecular mobility of PAC in the two w/o microemulsions (CM and LBM) than the o/w microemulsion--CPM. The in situ permeability of PAC through male CD-IGS rat intestine was 3- and 11-fold higher from LBM and CM, respectively, than that from the control clinical formulation, Taxol (CE, cremophor: ethanol) in a single pass perfusion study. PAC permeability was significantly increased in the presence of the pgp/CYP3A4 inhibitor cyclosporine A (CsA). This enhancement may be attributed to the pgp inhibitory effect of the surfactants, oil and/or the membrane perturbation effect of the surfactants. The oral disposition of PAC in CM, LBM and CPM compared

  11. Kinetic studies of Chromobacterium viscosum lipase in AOT water in oil microemulsions and gelatin microemulsion-based organogels.

    Science.gov (United States)

    Jenta, T R; Batts, G; Rees, G D; Robinson, B H

    1997-06-05

    Kinetic studies have shown that octyl decanoate synthesis by Chromobacterium viscosum (CV) lipase in sodium bis-2-(ethylhexyl) sulfosuccinate (AOT) water in oil (w/o) microemulsions occurs via the nonsequential (ping-pong) bi bi mechanism. There was evidence of single substrate inhibition by decanoic acid at high concentrations. Initial rate data yielded estimates for acid and alcohol Michaelis constants of ca. 10(-1) mol dm(-3) and a maximum rate under saturation conditions of ca. 10(-3) mol dm(-3) s(-1) for a lipase concentration of 0.36 mg cm(-3). CV lipase immobilized in AOT microemulsion-based organogels (MBGs) was also found to catalyze the synthesis of octyl decanoate according to the ping-pong bi bi mechanism. Reaction rates were similar in the free and immobilized systems under comparable conditions. Initial rates at saturating (but noninhibiting) substrate concentrations were first order with respect to CV lipase concentration in both w/o microemulsions and the MBG/oil systems. Gradients yielded an apparent k(cat) = 4.4 x 10(-4) mol g(-1) s(-1) in the case of w/o microemulsions, and 6.1 x 10(-4) mol g(-1) s(-1) for CV lipase immobilized in the MBGs. A third system comprising w/o microemulsions containing substrates and gelatin at concentrations comparable to those employed in the MBG formulations, provided a useful link between the conventional liquid microemulsion medium and the solid organogels. The nongelation of these intermediate systems stems from the early inclusion of substrate during a modified preparative protocol. The presence of substrate appears to prevent the development of a percolated microstructure that is thought to be a prerequisite for MBG formation. FT-NMR was employed as a semicontinuous in situ assay procedure. The apparent activity expressed by CV lipase in compositionally equivalent liquid and solid phase gelatin-containing systems was similar. An apparent activation energy of 24 +/- 2 kJ mol(-1) was determined by (1)H-NMR for

  12. Graphite furnace atomic absorption spectrometric determination of Ni and Pb in diesel and gasoline samples stabilized as microemulsion using conventional and permanent modifiers

    International Nuclear Information System (INIS)

    Matos Reyes, Mariela N.; Campos, Reinaldo C.

    2005-01-01

    A procedure for the graphite furnace atomic absorption spectrometric determination of Ni and Pb in diesel and gasoline samples was developed. Sample stabilization was necessary because of evident analyte losses that occurred immediately after sampling. Excellent long-term sample stabilization was observed by mixing different organic solvents with propan-1-ol and 50% vol/vol HNO 3 at a 3.3:6.5:1 volume ratio. For Pb, efficient thermal stabilization was obtained using aqueous Pd-Mg modifier as well as for Ir as permanent modifier. The drying temperature and ramp rate influenced the sensitivity obtained for Ni, and had to be carefully optimized. Taking this into account, the same sensitivity was attained in all investigated organic media stabilized as microemulsion. Thus, calibration with microemulsions prepared with a single organic solvent was possible, using aqueous or organic stock solutions. Commercial gasoline and diesel samples were directly analyzed after stabilization as microemulsion and by comparative UOP procedures. n-Hexane microemulsions were used for calibration, and good agreement was obtained between the results using the proposed and comparative procedures. Typical coefficients of variation (n = 6) ranged from 1% to 4%, and from 1% to 3% for Ni and Pb, respectively. Detection limits (k = 3) in the original gasoline or diesel samples, derived from 10 blank measurements, were 4.5 and 3.6 μg l -1 for Ni and Pb, respectively, comfortably below the values found in the analyzed samples

  13. To Model Chemical Reactivity in Heterogeneous Emulsions, Think Homogeneous Microemulsions.

    Science.gov (United States)

    Bravo-Díaz, Carlos; Romsted, Laurence Stuart; Liu, Changyao; Losada-Barreiro, Sonia; Pastoriza-Gallego, Maria José; Gao, Xiang; Gu, Qing; Krishnan, Gunaseelan; Sánchez-Paz, Verónica; Zhang, Yongliang; Dar, Aijaz Ahmad

    2015-08-25

    Two important and unsolved problems in the food industry and also fundamental questions in colloid chemistry are how to measure molecular distributions, especially antioxidants (AOs), and how to model chemical reactivity, including AO efficiency in opaque emulsions. The key to understanding reactivity in organized surfactant media is that reaction mechanisms are consistent with a discrete structures-separate continuous regions duality. Aggregate structures in emulsions are determined by highly cooperative but weak organizing forces that allow reactants to diffuse at rates approaching their diffusion-controlled limit. Reactant distributions for slow thermal bimolecular reactions are in dynamic equilibrium, and their distributions are proportional to their relative solubilities in the oil, interfacial, and aqueous regions. Our chemical kinetic method is grounded in thermodynamics and combines a pseudophase model with methods for monitoring the reactions of AOs with a hydrophobic arenediazonium ion probe in opaque emulsions. We introduce (a) the logic and basic assumptions of the pseudophase model used to define the distributions of AOs among the oil, interfacial, and aqueous regions in microemulsions and emulsions and (b) the dye derivatization and linear sweep voltammetry methods for monitoring the rates of reaction in opaque emulsions. Our results show that this approach provides a unique, versatile, and robust method for obtaining quantitative estimates of AO partition coefficients or partition constants and distributions and interfacial rate constants in emulsions. The examples provided illustrate the effects of various emulsion properties on AO distributions such as oil hydrophobicity, emulsifier structure and HLB, temperature, droplet size, surfactant charge, and acidity on reactant distributions. Finally, we show that the chemical kinetic method provides a natural explanation for the cut-off effect, a maximum followed by a sharp reduction in AO efficiency with

  14. Formulation and kinetic modeling of curcumin loaded intranasal mucoadhesive microemulsion

    Directory of Open Access Journals (Sweden)

    B Mikesh Patel

    2012-01-01

    Full Text Available It is a challenge to develop the optimum dosage form of poorly water-soluble drugs and to target them due to limited bioavailability, intra and inter subject variability. In this investigation, mucoadhesive microemulsion of curcumin was developed by water titration method taking biocompatible components for intranasal delivery and was characterized. Nasal ciliotoxicity studies were carried out using excised sheep nasal mucosa. in vitro release studies of formulations and PDS were performed. Labrafil M 1944 CS based microemulsion was transparent, stable and nasal non-ciliotoxic having particle size 12.32±0.81nm (PdI=0.223 and from kinetic modeling, the release was found to be Fickian diffusion for mucoadhesive microemulsion.

  15. Capillary condensation and gelling of microemulsions with clay additives.

    Science.gov (United States)

    Gvaramia, Manuchar; Mangiapia, Gaetano; Falus, Peter; Ohl, Michael; Holderer, Olaf; Frielinghaus, Henrich

    2018-04-22

    The capillary condensation in bicontinuous microemulsions takes place when two parallel surfaces are narrowed that result in a completely lamellar microemulsion. We expected that this phase transition is also observable when the amount of hydrophilic surfaces from clay particles is raised, because hydrophilic surfaces induce lamellar ordering locally. Using small angle neutron scattering, the structure of microemulsions was observed as a function of clay content. The critical concentration is indicated by discontinuous structural changes and depends on the platelet diameter and is explained by the free energy of the platelets competing with the fluctuating medium. The gel phase transition is observed in the spectroscopic measurements where the diffusion motion is widely suppressed in the gel phase, but otherwise superimposes with the membrane undulations. Copyright © 2018. Published by Elsevier Inc.

  16. Optimization of Microemulsion Based Transdermal Gel of Triamcinolone.

    Science.gov (United States)

    Jagdale, Swati; Chaudhari, Bhagyashree

    2017-01-01

    Triamcinolone is a long acting corticosteroid used in the treatment of arthritis, eczema, psoriasis and similar conditions which cause inflammation. Triamcinolone has half-life of 88min. Prolonged oral use is associated with gastrointestinal adverse effects as peptic ulcer, abdominal distention and ulcerative esophagitis as described in various patents. Microemulgel offers advantage of better stability, better loading capacity and controlled release especially for drug with short half life. Objective of the present study was to optimize microemulgel based transdermal delivery of triamcinolone. Saturated solubility of triamcinolone in various oils, surfactants and co-surfactants is estimated. Pseudo-ternary phase diagrams were constructed to determine the region of transparent microemulsion. Microemulsion was evaluated for globule size (FE-SEM, zetasizer), % transmittance, pH, viscosity, conductivity etc. Design of experiment was used to optimize microemulsion based gel. Carbopol 971P and HPMC K100M were used as independent variables. Microemulsion based gel was evaluated for in-vitro as well as ex-vivo parameters. Microemulsion was formulated with oleic acid, lauroglycol FCC and propylene glycol. PDI 0.197 indicated microemulsion is mono-disperse. 32 factorial design gave batch F8 as optimized. Design expert suggested drug release; gel viscosity and bio-adhesive strength were three significant dependant factors affecting the transdermal delivery. F8 showed drug release 92.62.16±1.22% through egg membrane, 95.23±1.44% through goat skin after 8hr and Korsmeyer-Peppas release model was followed. It can be concluded that a stable, effective controlled release transdermal microemulgel was optimised for triamcinolone. This would be a promising tool to deliver triamcinolone with enhanced bioavailability and reduced dosing frequency. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  17. Decontamination of radioactive clothing using microemulsion in carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Jaeryong; Jang, Jina; Park, Kwangheon; Kim, Hongdoo; Kim, Hakwon [Kyunghee Univ., Seoul (Korea, Republic of); Yim, Sanghak; Yoon, Weonseob [Ulchin Nuclear Power Site, Ulchin (Korea, Republic of)

    2006-07-01

    Nuclear power is intrinsically a clean energy source due to its high energy density and low generation of waste. However, as the nuclear industry grows, a variety of radioactive wastes are increased gradually. Major subjects include contaminated components, tools, equipment, containers and facilities as well as nuclear waste such as uranium scrap and radioactive clothing. The radioactive waste can be classified by its creation. There are Trans-Uranium Nuclides (TRU), Fission Products (FP) and corrosion products. Nuclear decontamination has become an important issue in the nuclear industry. The conventional methods have some problems such as the production of secondary wastes and the use of toxic solvents. We need to develop a new method of decontamination and suggest a use of microemulsion in carbon dioxide to overcome these disadvantages. The microemulsion is the clear solution that contains the water, surfactant and carbon dioxide. The surfactant surrounded the droplet into carbon dioxide and this state is thermodynamically stable. That is, the microemulsion has a structure similar to that of a conventional water-based surfactant system. Generally, the size of droplet is about 5 {approx} 10nm. The microemulsion is able to decontaminate radioactive waste so that the polar substance is removed by water and the non-polar substance is removed by carbon dioxide. After the decontamination process, the microemulsion is separated easily to surfactant and water by decreasing the pressure under the cloud point. This way, only radioactive wastes are left in the system. Cleaned carbon dioxide is then collected and reused. Thus, there are no secondary wastes. Carbon dioxide is considered an alternative process medium. This is because it is non-toxic, non-flammable, inexpensive and easy to handle. Additionally, the tunable properties of carbon dioxide through pressure and temperature control are versatile for use in extracting organic materials. In this paper, we examine the

  18. Decontamination of radioactive clothing using microemulsion in carbon dioxide

    International Nuclear Information System (INIS)

    Yoo, Jaeryong; Jang, Jina; Park, Kwangheon; Kim, Hongdoo; Kim, Hakwon; Yim, Sanghak; Yoon, Weonseob

    2006-01-01

    Nuclear power is intrinsically a clean energy source due to its high energy density and low generation of waste. However, as the nuclear industry grows, a variety of radioactive wastes are increased gradually. Major subjects include contaminated components, tools, equipment, containers and facilities as well as nuclear waste such as uranium scrap and radioactive clothing. The radioactive waste can be classified by its creation. There are Trans-Uranium Nuclides (TRU), Fission Products (FP) and corrosion products. Nuclear decontamination has become an important issue in the nuclear industry. The conventional methods have some problems such as the production of secondary wastes and the use of toxic solvents. We need to develop a new method of decontamination and suggest a use of microemulsion in carbon dioxide to overcome these disadvantages. The microemulsion is the clear solution that contains the water, surfactant and carbon dioxide. The surfactant surrounded the droplet into carbon dioxide and this state is thermodynamically stable. That is, the microemulsion has a structure similar to that of a conventional water-based surfactant system. Generally, the size of droplet is about 5 ∼ 10nm. The microemulsion is able to decontaminate radioactive waste so that the polar substance is removed by water and the non-polar substance is removed by carbon dioxide. After the decontamination process, the microemulsion is separated easily to surfactant and water by decreasing the pressure under the cloud point. This way, only radioactive wastes are left in the system. Cleaned carbon dioxide is then collected and reused. Thus, there are no secondary wastes. Carbon dioxide is considered an alternative process medium. This is because it is non-toxic, non-flammable, inexpensive and easy to handle. Additionally, the tunable properties of carbon dioxide through pressure and temperature control are versatile for use in extracting organic materials. In this paper, we examine the

  19. Optimized mixed oils remarkably reduce the amount of surfactants in microemulsions without affecting oral bioavailability of ibuprofen by simultaneously enlarging microemulsion areas and enhancing drug solubility.

    Science.gov (United States)

    Chen, Yizhen; Tuo, Jue; Huang, Huizhi; Liu, Dan; You, Xiuhua; Mai, Jialuo; Song, Jiaqi; Xie, Yanqi; Wu, Chuanbin; Hu, Haiyan

    2015-06-20

    The toxicity and irritation associated with high amounts of surfactants restrict the extensive utilization of microemulsions. To address these shortcomings, employing mixed oils to enlarge microemulsion areas therefore reducing surfactant contents is a promising strategy. However, what kinds of mixed oils are more efficient in enlarging microemulsion areas still remains unclear. In this research, we found that the chain length and degree of unsaturation of oils play a key role in enlarging microemulsion areas. The combination of moderate chain saturated oil caprylic/capric triglyceride (GTCC) with long chain unsaturated oil glycerol trioleate significantly increased the microemulsion areas. Solubility of ibuprofen in the mixed oils was unexpectedly and remarkably increased (almost 300mg/mL) compared with that (around 100mg/mL) of the single oil (GTCC), which also resulted in greatly increased solubility of ibuprofen in mixed oils-containing microemulsions. By optimizing the mixed oil formulation, the absolute amount of surfactant in drug-loaded microemulsions was reduced but increased drug oral bioavailability in rats was maintained. It could be concluded that the combined use of moderate chain oils and long chain unsaturated oils could not only acquire enlarged microemulsion areas but also enhanced drug solubility, therefore doubly reducing surfactant amount, which is extremely beneficial for developing safe microemulsions. Copyright © 2015. Published by Elsevier B.V.

  20. Tc-99m Radiolabeled Alendronate Sodium Microemulsion: Characterization and Permeability Studies Across Caco-2 Cells.

    Science.gov (United States)

    Elitez, Yetkin; Ekinci, Meliha; Ilem-Ozdemir, Derya; Gundogdu, Evren; Asikoglu, Makbule

    2018-01-01

    Alendronate sodium (ALD) is used orally but it is poorly absorbed from the gastrointestinal (GI) tract. For this reason, microemulsion system was chosen to evaluate ALD from the GI tract after oral delivery. This study was aimed to prepare water-in-oil (w/o) microemulsion formulation of ALD and evaluate the permeability of ALD microemulsion from Caco-2 cell lines with radioactive and nonradioactive studies. The ALD microemulsion was developed by using pseudo-ternary phase diagram and composed of Soybean oil, Colliphor EL, Tween 80, Transcutol and distilled water. The prepared ALD microemulsion was characterized by physical appearance, droplet size, viscosity, pH, electrical conductivity and refractive index. The stability of the formulation was investigated for 6 months at 25±2°C/60±5% of relative humidity (RH) as well as at 40±2°C/75±5% RH. After that 1 mg of ALD was radiolabeled with 99mTc and added to microemulsion. The permeability studies were performed with both 99mTc-ALD microemulsion and ALD microemulsion. The experimental results suggested that ALD microemulsion presented adequate stability with droplet size varying from 37.8±0.9 to 39.9±1.2 nm during incubation time. In addition, ALD microemulsion was radiolabeled with high labeling efficiency (>95%). In a non-radioactive study, ALD permeability was found to be 45 µg.mL-1 and microemulsion has high permeability percentage when compared to another study. The novel w/o microemulsion formulation has been developed for oral delivery of ALD. Based on the results, permeability of ALD could be significantly improved by the microemulsion formulation. In addition, 99mTc-ALD microemulsion in capsule can be used for bone disease treatment and diagnosis. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  1. Formulation and evaluation of microemulsion-based hydrogel for topical delivery.

    Science.gov (United States)

    Sabale, Vidya; Vora, Sejal

    2012-07-01

    The purpose of this study was to develop microemulsion-based hydrogel formulation for topical delivery of bifonazole with an objective to increase the solubility and skin permeability of the drug. Oleic acid was screened as the oil phase of microemulsions, due to a good solubilizing capacity of the microemulison systems. The pseudo-ternary phase diagrams for microemulsion regions were constructed using oleic acid as the oil, Tween 80 as the surfactant and isopropyl alcohol (IPA) as the cosurfactant. Various microemulsion formulations were prepared and optimized by 3(2) factorial design on the basis of percentage (%) transmittance, globule size, zeta potential, drug release, and skin permeability. The abilities of various microemulsions to deliver bifonazole through the skin were evaluated ex vivo using Franz diffusion cells fitted with rat skins. The Hydroxy Propyl Methyl Cellulose (HPMC) K100 M as a gel matrix was used to construct the microemulsion-based hydrogel for improving the viscosity of microemulsion for topical administration. The optimized microemulsion-based hydrogel was evaluated for viscosity, spreadability, skin irritancy, skin permeability, stability, and antifungal activity by comparing it with marketed bifonazole cream. The mechanism of drug release from microemulsion-based hydrogel was observed to follow zero order kinetics. The studied optimized microemulsion-based hydrogel showed a good stability over the period of 3 months. Average globule size of optimized microemulsion (F5) was found to be 18.98 nm, zeta potential was found to be -5.56 mv, and permeability of drug from microemulsion within 8 h was observed 84%. The antifungal activity of microemulsion-based hydrogel was found to be comparable with marketed cream. The results indicate that the studied microemulsion-based hydrogel (F5) has a potential for sustained action of drug release and it may act as promising vehicle for topical delivery of ibuprofen.

  2. Peroxyl radical reactions with carotenoids in microemulsions: Influence of microemulsion composition and the nature of peroxyl radical precursor.

    Science.gov (United States)

    El-Agamey, Ali; McGarvey, David J

    2016-01-01

    The reactions of acetylperoxyl radicals with different carotenoids (7,7'-dihydro-β-carotene and ζ-carotene) in SDS and CTAC microemulsions of different compositions were investigated using laser flash photolysis (LFP) coupled with kinetic absorption spectroscopy. The primary objective of this study was to explore the influence of microemulsion composition and the type of surfactant used on the yields and kinetics of various transients formed from the reaction of acetylperoxyl radicals with carotenoids. Also, the influence of the site (hydrocarbon phases or aqueous phase) of generation of the peroxyl radical precursor was examined by using 4-acetyl-4-phenylpiperidine hydrochloride (APPHCl) and 1,1-diphenylacetone (11DPA) as water-soluble and lipid-soluble peroxyl radical precursors, respectively. LFP of peroxyl radical precursors with 7,7'-dihydro-β-carotene (77DH) in different microemulsions gives rise to the formation of three distinct transients namely addition radical (λmax=460 nm), near infrared transient1 (NIR, λmax=700 nm) and 7,7'-dihydro-β-carotene radical cation (77DH(•+), λmax=770 nm). In addition, for ζ-carotene (ZETA) two transients (near infrared transient1 (NIR1, λmax=660 nm) and ζ-carotene radical cation (ZETA(•+), λmax=730-740 nm)) are generated following LFP of peroxyl radical precursors in the presence of ζ-carotene (ZETA) in different microemulsions. The results show that the composition of the microemulsion strongly influences the observed yield and kinetics of the transients formed from the reactions of peroxyl radicals (acetylperoxyl radicals) with carotenoids (77DH and ZETA). Also, the type of surfactant used in the microemulsions influences the yield of the transients formed. The dependence of the transient yields and kinetics on microemulsion composition (or the type of surfactant used in the microemulsion) can be attributed to the change of the polarity of the microenvironment of the carotenoid. Furthermore, the nature of

  3. Microemulsion based hybrid biofuels using glycerol monooleate

    International Nuclear Information System (INIS)

    Bora, Plaban; Konwar, Lakhya Jyoti; Deka, Dhanapati

    2016-01-01

    Highlights: • Fuel quality of GMO based MHBFs. • Effect of externally added monoglyceride surfactant (GMO) on fuel characteristics of MHBF. • Structural and dynamic behaviors of GMO based MHBFs. • Can offer strong candidature for future biofuel industry. - Abstract: The present investigation aims to highlighten the effect of monoglyceride surfactant (GMO) on structure and dynamic behavior and other fuel characteristics of microemulsion based hybrid biofuels (MHBFs). Fuel quality of MHBFs formulated using purified GMO (>90%), which was prepared by esterification of glycerol, was investigated in the study. Phase behaviors, droplet size distribution, number of droplets present in the system, average droplet size and average length of surface active agents were studied as a part of structural investigations of the GMO based MHBFs. Diffusion coefficient, energy barrier to droplet coalescence and rate of coalescence of droplets were also investigated for the formulated MHBFs. The number of droplets, length of surface active agent and the diffusion co-efficient were in the ranges of 1.87 × 10"2"1–5.66 × 10"2"1/m"3, 0.92–1.07 nm and 1.00 × 10"−"1"1–1.79 × 10"−"1"1 m"2/s, respectively. The rate of droplet coalescence was obtained in the range 2.77 × 10"−"4–8.78 × 10"−"4 times the collision factor. MHBFs incorporating the glycerol derived bio-based nonionic surfactant GMO exhibited viscosity of 4.12 mm"2/s (at 40 °C), gross calorific value (GCV) of 39.17 MJ/kg and pour point of −7 °C.

  4. Enhanced effect and mechanism of water-in-oil microemulsion as an oral delivery system of hydroxysafflor yellow A

    Science.gov (United States)

    Qi, Jianping; Zhuang, Jie; Wu, Wei; Lu, Yi; Song, Yunmei; Zhang, Zhetao; Jia, Jia; Ping, Qineng

    2011-01-01

    Background: A microemulsion is an effective formulation for improving the oral bioavailability of poorly soluble drugs. In this paper, a water-in-oil (w/o) microemulsion was investigated as a system for enhancing the oral bioavailability of Biopharmaceutic Classification System (BCS) III drugs. Methods: The microemulsion formulation was optimized using a pseudoternary phase diagram, comprising propylene glycol dicaprylocaprate (PG), Cremophor® RH40, and water (30/46/24 w/w). Results: The microemulsion increased the oral bioavailability of hydroxysafflor yellow A which was highly water-soluble but very poorly permeable. The relative bioavailability of hydroxysafflor yellow A microemulsion was about 1937% compared with a control solution in bile duct-nonligated rats. However, the microemulsion showed lower enhanced absorption ability in bile duct-ligated rats, and the relative bioavailability was only 181%. In vitro experiments were further employed to study the mechanism of the enhanced effect of the microemulsion. In vitro lipolysis showed that the microemulsion was digested very quickly by pancreatic lipase. About 60% of the microemulsion was digested within 1 hour. Furthermore, the particle size of the microemulsion after digestion was very small (53.3 nm) and the digested microemulsion had high physical stability. An everted gut sac model demonstrated that cumulative transport of the digested microemulsion was significantly higher than that of the diluted microemulsion. Conclusion: These results suggested that digestion of the microemulsion by pancreatic lipase plays an important role in enhancing oral bioavailability of water-soluble drugs. PMID:21720510

  5. Development and Evaluation of a Novel Microemulsion of Dexamethasone and Tobramycin for Topical Ocular Administration.

    Science.gov (United States)

    Bachu, Rinda Devi; Stepanski, Marina; Alzhrani, Rami M; Jung, Rose; Boddu, Sai H S

    2018-05-01

    The purpose of this study was to develop and evaluate a novel dexamethasone- and tobramycin-loaded microemulsion for its potential for treating anterior segment eye infections. The microemulsion was evaluated for pH, particle size, zeta potential, light transmittance, morphology, and in vitro drug release. Sterility of the microemulsion was evaluated by direct as well as plate inoculation methods. Anti-inflammatory activity of dexamethasone, bactericidal activity of tobramycin, and cytotoxicity of the microemulsion were assessed and compared to that of the marketed eye drop suspension (Tobradex ® ). Histological evaluation was performed in bovine corneas to assess the safety of microemulsion in comparison to Tobradex suspension. In addition, the stability of the microemulsion was studied at 4°C, 25°C, and 40°C. The pH of the microemulsion was close to the pH of tear fluid. The microemulsion displayed an average globule size under 20 nm, with light transmittance around 95%-100%. The aseptically prepared microemulsion remained sterile for up to 14 days. The cytotoxicity of the microemulsion in bovine corneal endothelial cells was comparable to that of the Tobradex suspension. The anti-inflammatory activity of dexamethasone and the antibacterial activity of tobramycin from the microemulsion were significantly higher than those of the Tobradex suspension (P microemulsion was found to be stable at 4°C and 25°C for 3 months. In conclusion, the developed microemulsion could be explored as a suitable alternative to the marketed suspension for treating anterior segment eye infections.

  6. In vitro cellular uptake of evodiamine and rutaecarpine using a microemulsion.

    Science.gov (United States)

    Zhang, Yong-Tai; Huang, Zhe-Bin; Zhang, Su-Juan; Zhao, Ji-Hui; Wang, Zhi; Liu, Ying; Feng, Nian-Ping

    2012-01-01

    To investigate the cellular uptake of evodiamine and rutaecarpine in a microemulsion in comparison with aqueous suspensions and tinctures. A microemulsion was prepared using the dropwise addition method. Mouse skin fibroblasts were cultured in vitro to investigate the optimal conditions for evodiamine and rutaecarpine uptake with different drug concentrations and administration times. Under optimal conditions, the cellular uptake of microemulsified drugs was assayed and compared to tinctures and aqueous suspensions. Rhodamine B labeling and laser scanning confocal microscopy (LSCM) were used to explore the distribution of fluorochrome transferred with the microemulsion in fibroblasts. Cellular morphology was also investigated, using optical microscopy to evaluate microemulsion-induced cellular toxicity. The maximum cellular drug uptake amounts were obtained with a 20% concentration (v/v) of microemulsion and an 8 hour administration time. Drug uptake by mouse skin fibroblasts was lowest when the drugs were loaded in microemulsion. After incubation with rhodamine B-labeled microemulsion for 8 hours, the highest fluorescence intensity was achieved, and the fluorochrome was primarily distributed in the cytochylema. No obvious cellular morphologic changes were observed with the administration of either the microemulsion or the aqueous suspension; for the tincture group, however, massive cellular necrocytosis was observed. The lower cellular uptake with microemulsion may be due to the fact that most of the drug loaded in the microemulsion vehicle was transported via the intercellular space, while a small quantity of free drug (released from the vehicle) was ingested through transmembrane transport. Mouse skin fibroblasts rarely endocytosed evodiamine and rutaecarpine with a microemulsion as the vehicle. The microemulsion had no obvious effect on cellular morphology, suggesting there is little or no cellular toxicity associated with the administration of microemulsion on

  7. Structural and magnetic characterization of YIG particles prepared using microemulsions

    International Nuclear Information System (INIS)

    Teijeiro, A.G.; Baldomir, D.; Rivas, J.; Paz, S.; Vaqueiro, P.; Lopez Quintela, A.

    1995-01-01

    Yttrium-iron-garnet (YIG) particles have been synthesized using the microemulsion technique. A comparison of ferrite powders obtained by this method and those prepared by sol-gel and solid state reactions is reported. We have studied both the magnetic and structural properties and have found a dependence on annealing temperatures. ((orig.))

  8. Microemulsions in the Preparation of Highly Active Combustion Catalysts

    Czech Academy of Sciences Publication Activity Database

    Rymeš, Jan; Ehret, G.; Hilaire, L.; Boutonnet, M.; Jirátová, Květa

    2002-01-01

    Roč. 75, 1-4 (2002), s. 297-303 ISSN 0920-5861 R&D Projects: GA ČR GA106/02/0523 Institutional research plan: CEZ:AV0Z4072921 Keywords : microemulsion s * catalytic combustion * VOC Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.146, year: 2002

  9. Acute and sub-chronic toxicity studies of honokiol microemulsion.

    Science.gov (United States)

    Zhang, Qianqian; Li, Jianguo; Zhang, Wei; An, Quan; Wen, Jianhua; Wang, Aiping; Jin, Hongtao; Chen, Shizhong

    2015-04-01

    The purpose of this study was to investigate the acute and sub-chronic toxicity of honokiol microemulsion. In the acute toxicity tests, the mice were intravenously injected graded doses of honokiol microemulsion and were observed for toxic symptoms and mortality daily for 14 days. In the sub-chronic toxicity study, rats were injected honokiol microemulsion at doses of 100, 500, 2500 μg/kg body weight (BW) for 30 days. After 30 days treatment and 14 days recovery, the rats were sacrificed for hematological, biochemical and histological examination. In the acute toxicity tests, the estimated median lethal dosage (LD50) was 50.5mg/kg body weight in mice. In the sub-chronic toxicity tests, the non-toxic reaction dose was 500 μg/kg body weight. In each treatment group, degeneration or/and necrosis in vascular endothelial cells and structure change of vessel wall can be observed in the injection site (cauda vein) of a few animals while there were no changes in the vessels of other organs. The overall findings of this study indicate that the honokiol microemulsion is non-toxic up to 500 μg/kg body weight, and it has irritation to the vascular of the injection site which should be paid attention to in clinical medication. Copyright © 2015. Published by Elsevier Inc.

  10. Microemulsion-enhanced remediation of soils contaminated with organochlorine pesticides.

    Science.gov (United States)

    Zhang, Yanlin; Wong, Jonathan W C; Zhao, Zhenyong; Selvam, Ammaiyappan

    2011-12-01

    Soil contaminated by organic pollutants, especially chlorinated aromatic compounds such as DDT (1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane), is an environmental concern because of the strong sorption of organochlorine pesticide onto the soil matrix and persistence in the environment. The remediation of organochlorine pesticide contaminated soils through microemulsion is an innovative technology to expedite this process. The remediation efficiency was evaluated by batch experiments through studying the desorption of DDT and hexachlorocyclohexane (y-HCH) and sorption of microemulsion composed of Triton X-100, 1-pentanol and linseed oil in the soil-surfactant-water suspension system. The reduction of desorption efficiency caused by the sorption loss of microemulsion components onto the soil could be corrected by the appropriate adjustment of C/S (Cosurfactant/Surfactant) and O/S (Oil/Surfactant) ratio. The C/S and O/S ratios of 1:2 and 3:20 were suitable to desorb DDT and gamma-HCH from the studied soils because of the lower sorption of Triton X-100 onto the soil. Inorganic salts added in microemulsion increased the pesticides desorption efficiency of pesticides and calcium chloride has a stronger ability to enhance the desorption of DDT than sodium chloride. From the remediation perspective, the balance of surfactant or cosurfactant sorbed to soil and desorption efficiency should be taken into consideration to enhance the remediation of soils contaminated by organochlorine pesticides.

  11. Singlet oxygenation in microemulsion catalysed by vanadium chloroperoxidase

    NARCIS (Netherlands)

    Renirie, R.; Pierlot, C.; Wever, R.; Aubry, J.-M.

    2009-01-01

    Non-ionic microemulsions compatible with the enzyme vanadium chloroperoxidase were designed to perform singlet oxygenation of apolar substrates. The media were based on mono- and polydisperse ethoxylated fatty alcohols (CiEj). octane and aqueous buffer. "Fish" diagrams were determined to identify

  12. Antinociceptive activity of Delta9-tetrahydrocannabinol non-ionic microemulsions.

    Science.gov (United States)

    Lazzari, P; Fadda, P; Marchese, G; Casu, G L; Pani, L

    2010-06-30

    Delta(9)-Tetrahydrocannabinol (Delta(9)-THC), the major psychoactive constituent of Cannabis sativa L., has been widely studied for its potential pharmaceutical application in the treatment of various diseases and disturbs. This sparingly soluble terpeno-phenolic compound is not easy to handle and to be formulated in pharmaceutical preparations. The aim of this work was to develop a stable aqueous Delta(9)-THC formulation acceptable for different ways of administration, and to evaluate the therapeutic properties of the new Delta(9)-THC based preparation for pain treatment. Due to the thermodynamic stability and advantages of microemulsion based systems, the study was focused on the identification of aqueous microemulsion based systems containing Delta(9)-THC. Oil in water Delta(9)-THC microemulsions were individuated through phase diagrams construction, using the non-ionic surfactant Solutol HS15, being this surfactant acceptable for parenteral administration in human. A selected microemulsion samples containing 0.2 wt% of Delta(9)-THC, stable up to 52 degrees C, was successfully assayed on animal models of pain. Significant antinociceptive activity has been detected by both intraperitoneal and intragastric administration of the new Delta(9)-THC pharmaceutical preparation. The effect has been highlighted in shorter time if compared to a preparation of the same active principle based on previously reported conventional preparation. 2010 Elsevier B.V. All rights reserved.

  13. NMR characterisation and transdermal drug delivery potential of microemulsion systems

    DEFF Research Database (Denmark)

    Kreilgaard, Mads; Pedersen, E J; Jaroszewski, J W

    2000-01-01

    The purpose of this study was to investigate the influence of structure and composition of microemulsions (Labrasol/Plurol Isostearique/isostearylic isostearate/water) on their transdermal delivery potential of a lipophilic (lidocaine) and a hydrophilic model drug (prilocaine hydrochloride), and ...

  14. Thermally conductive, electrically insulating and melt-processable polystyrene/boron nitride nanocomposites prepared by in situ reversible addition fragmentation chain transfer polymerization

    International Nuclear Information System (INIS)

    Huang, Xingyi; Wang, Shen; Zhu, Ming; Yang, Ke; Jiang, Pingkai; Bando, Yoshio; Golberg, Dmitri; Zhi, Chunyi

    2015-01-01

    Thermally conductive and electrically insulating polymer/boron nitride (BN) nanocomposites are highly attractive for various applications in many thermal management fields. However, so far most of the preparation methods for polymer/BN nanocomposites have usually caused difficulties in the material post processing. Here, an in situ grafting approach is designed to fabricate thermally conductive, electrically insulating and post-melt processable polystyrene (PS)/BN nanosphere (BNNS) nanocomposites by initiating styrene (St) on the surface functionalized BNNSs via reversible addition fragmentation chain transfer polymerization. The nanocomposites exhibit significantly enhanced thermal conductivity. For example, at a St/BN feeding ratio of 5:1, an enhancement ratio of 1375% is achieved in comparison with pure PS. Moreover, the dielectric properties of the nanocomposites show a desirable weak dependence on frequency, and the dielectric loss tangent of the nanocomposites remains at a very low level. More importantly, the nanocomposites can be subjected to multiple melt processing to form different shapes. Our method can become a universal approach to prepare thermally conductive, electrically insulating and melt-processable polymer nanocomposites with diverse monomers and nanofillers. (paper)

  15. On Small-Angle Neutron Scattering from Microemulsion Droplets the Role of Shape Fluctuations

    CERN Document Server

    Lisy, V

    2001-01-01

    The form factor and intensity of static neutron scattering from microemulsion droplets are calculated. The droplet is modeled by a double-layered sphere consisting of a fluid core and a thin surfactant layer, immersed in another fluid. All the three components are incompressible and characterized by different scattering length densities. As distinct from previous descriptions of small-angle neutron scattering (SANS), we consistently take into account thermal fluctuations of the droplet shape, to the second order of the fluctuations of the droplet radius. The properties of the layer are described within Helfrich's concept of the elasticity of curved interfaces. It is shown that in many cases the account for the fluctuations is essential for the interpretation of SANS. Information about two elastic constants \\kappa and \\bar\\kappa (so far extracted from the experiments in the combination 2\\kappa+\\bar\\kappa) can be now simultaneously obtained from SANS for system in conditions of two-phase coexistence. As an illu...

  16. Investigation of microemulsion system for transdermal delivery of itraconazole

    Science.gov (United States)

    Chudasama, Arpan; Patel, Vineetkumar; Nivsarkar, Manish; Vasu, Kamala; Shishoo, Chamanlal

    2011-01-01

    A new oil-in-water microemulsion-based (ME) gel containing 1% itraconazole (ITZ) was developed for topical delivery. The solubility of ITZ in oils and surfactants was evaluated to identify potential excipients. The microemulsion existence ranges were defined through the construction of the pseudoternary phase diagrams. The optimized microemulsion was characterized for its morphology and particle size distribution. The optimized microemulsion was incorporated into polymeric gels of Lutrol F127, Xanthan gum, and Carbopol 934 for convenient application and evaluated for pH, drug content, viscosity, and spreadability. In vitro drug permeation of ME gels was determined across excised rat skins. Furthermore, in vitro antimycotic inhibitory activity of the gels was conducted using agar-cup method and Candida albicans as a test organism. The droplet size of the optimized microemulsion was found to be <100 nm. The optimized Lutrol F 127 ME gel showed pH in the range of 5.68±0.02 and spreadability of 5.75±1.396 gcm/s. The viscosity of ME gel was found to be 1805.535±542.4 mPa s. The permeation rate (flux) of ITZ from prepared ME gel was found to be 4.234 μg/cm/h. The release profile exhibited diffusion controlled mechanism of drug release from ME ITZ gel. The developed ME gels were nonirritant and there was no erythema or edema. The antifungal activity of ITZ showed the widest zone of inhibition with Lutrol F127 ME gel. These results indicate that the studied ME gel may be a promising vehicle for topical delivery of ITZ. PMID:22171289

  17. Reversible Thermoset Adhesives

    Science.gov (United States)

    Mac Murray, Benjamin C. (Inventor); Tong, Tat H. (Inventor); Hreha, Richard D. (Inventor)

    2016-01-01

    Embodiments of a reversible thermoset adhesive formed by incorporating thermally-reversible cross-linking units and a method for making the reversible thermoset adhesive are provided. One approach to formulating reversible thermoset adhesives includes incorporating dienes, such as furans, and dienophiles, such as maleimides, into a polymer network as reversible covalent cross-links using Diels Alder cross-link formation between the diene and dienophile. The chemical components may be selected based on their compatibility with adhesive chemistry as well as their ability to undergo controlled, reversible cross-linking chemistry.

  18. Food grade microemulsion systems: canola oil/lecithin:n-propanol/water.

    Science.gov (United States)

    Abbasi, Soleiman; Radi, Mohsen

    2016-03-01

    In this study, the capability of a natural surfactant, lecithin, and the influence of ionic strength, pH, and temperature on some properties of a food grade microemulsion system were evaluated. For this purpose, the pseudoternary phase diagrams of canola oil/lecithin:n-propanol/water microemulsions in the presence of different salts (NaCl and CaCl2), ionic strengths, pHs, and temperatures were constructed. Our findings showed that the presence of salts slightly increased the W/O areas on the phase diagrams, whereas pH variation was not effective on the microemulsion formation. The expansion of microemulsion areas with temperature indicated the greater triglycerides solubilization capacity of lecithin based microemulsions at higher temperatures. These findings revealed the efficiency of lecithin-based microemulsion system for solubilization of triglycerides which can potentially be used for extraction of edible vegetable oils particularly canola oil. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Magnetic Reversal and Thermal Stability of CoFeB Perpendicular Magnetic Tunnel Junction Arrays Patterned by Block Copolymer Lithography

    KAUST Repository

    Tu, Kun-Hua; Fernandez Martin, Eduardo; almasi, hamid; Wang, Weigang; Navas Otero, David; Ntetsikas, Konstantinos; Moschovas, Dimitrios; Avgeropoulos, Apostolos; Ross, Caroline A

    2018-01-01

    Dense arrays of pillars, with diameters of 64 and 25 nm, were made from a perpendicular CoFeB magnetic tunnel junction thin film stack using block copolymer lithography. While the soft layer and hard layer in the 64 nm pillars reverse at different

  20. Augmented bioavailability of felodipine through an α-linolenic acid-based microemulsion.

    Science.gov (United States)

    Singh, Mahendra; Kanoujia, Jovita; Parashar, Poonam; Arya, Malti; Tripathi, Chandra B; Sinha, V R; Saraf, Shailendra K; Saraf, Shubhini A

    2018-02-01

    The oral bioavailability of felodipine, a dihydropyridine calcium channel antagonist, is about 15%. This may be due to poor water solubility, and a lower intestinal permeability than a BCS class I drug, and hepatic first-pass metabolism of the drug. Many drugs are unpopular due to solubility issues. The goal of this study was to develop and optimize a felodipine-containing microemulsion to improve the intestinal permeability and bioavailability of the drug. The felodipine microemulsions were developed with the selected components, i.e., α-linolenic acid as the oil phase, Tween 80 as a surfactant, and isopropyl alcohol as co-surfactant using Box-Behnken design and characterized for in vitro release and particle size. The optimized felodipine-loaded microemulsion was investigated for physicochemical interaction, surface morphology, intestinal permeability, rheology, cytotoxicity, cellular uptake, pharmacodynamic (electrocardiogram and heart rate variability), and pharmacokinetic studies to explore its suitability as a promising oral drug delivery system for the treatment of hypertension. The optimized felodipine-loaded microemulsion showed significantly higher (P microemulsion showed biocompatibility and no cytotoxicity. Cellular uptake studies confirmed payload delivery to a cellular site on the J774.A1 cell line. The rheology study of the optimized felodipine-loaded microemulsion revealed Newtonian-type flow behavior and discontinuous microemulsion formation. In pharmacodynamic studies, significant differences in parameters were observed between the optimized felodipine-loaded microemulsion and marketed formulation. The optimized felodipine-loaded microemulsion showed significantly higher (p microemulsion (84.53 ± 10.73 μg h/ml) was significantly higher (p microemulsion was about 308.3% higher than that of the marketed formulation. The results demonstrate that the prepared microemulsion is an advanced and efficient oral delivery system of felodipine

  1. Lower irritation microemulsion-based rotigotine gel: formulation optimization and in vitro and in vivo studies.

    Science.gov (United States)

    Wang, Zheng; Mu, Hong-Jie; Zhang, Xue-Mei; Ma, Peng-Kai; Lian, Sheng-Nan; Zhang, Feng-Pu; Chu, Sheng-Ying; Zhang, Wen-Wen; Wang, Ai-Ping; Wang, Wen-Yan; Sun, Kao-Xiang

    2015-01-01

    Rotigotine is a potent and selective D1, D2, and D3 dopaminergic receptor agonist. Due to an extensive first-pass effect, it has a very low oral bioavailability (approximately 0.5% in rats). The present investigation aimed to develop a microemulsion-based hydrogel for transdermal rotigotine delivery with lower application site reactions. Pseudoternary phase diagrams were constructed to determine the region of oil in water (o/w)-type microemulsion. Central composite design was used to support the pseudoternary phase diagrams and to select homogeneous and stable microemulsions with an optimal amount of rotigotine permeation within 24 hours. In vitro skin permeation experiments were performed, using Franz diffusion cells, to compare rotigotine-loaded microemulsions with rotigotine solutions in oil. The optimized formulation was used to prepare a microemulsion-based hydrogel, which was subjected to bioavailability and skin irritancy studies. The selected formulations of rotigotine-loaded microemulsions had enhanced flux and permeation coefficients compared with rotigotine in oil. The optimum microemulsion contained 68% water, 6.8% Labrafil(®), 13.44% Cremophor(®) RH40, 6.72% Labrasol(®), and 5.04% Transcutol(®) HP; the drug-loading rate was 2%. To form a microemulsion gel, 1% Carbomer 1342 was added to the microemulsion. The bioavailability of the rotigotine-loaded microemulsion gel was 105.76%±20.52% with respect to the marketed rotigotine patch (Neupro(®)). The microemulsion gel irritated the skin less than Neupro. A rotigotine microemulsion-based hydrogel was successfully developed, and an optimal formulation for drug delivery was identified. This product could improve patient compliance and have broad marketability.

  2. Development and Characterization of a Microemulsion System Containing Amphotericin B with Potential Ocular Applications.

    Science.gov (United States)

    da Silveira, Walteçá Louis Lima; Damasceno, Bolivar P G L; Ferreira, Laura F; Ribeiro, Izabel L S; Silva, Karolyne S; Silva, André Leandro; Giannini, Maria José Mendes; da Silva-Júnior, Arnóbio Antônio; de Oliveira, Anselmo Gomes; do Egito, E Sócrates Tabosa

    2016-01-01

    Amphotericin B eye drops are widely used in the treatment of ocular infections. However, amphotericin's toxicity leads to low patient compliance and aggravation of symptoms. This work describes the development of a microemulsion system containing amphotericin B, aiming for its use in ocular applications. The microemulsion was developed by the titration technique. The physicochemical characteristics were determined with both loaded and unloaded amphotericin B-microemulsion. The nanostructures were analyzed by polarized light microscopy. The microdilution method was used to establish the minimum inhibitory concentration against fungal strains, and, therefore, evaluate the microemulsion activity. Additionally, in order to evaluate the microemulsion toxicity an in vitro toxicity assay against red blood cells was performed. The performed studies showed that the presence of amphotericin B loaded into the system did not induce serious changes in the physicochemical properties of the microemulsion when compared to the unloaded system. The spectrophotometric studies depicted amphotericin B-self-associated species, which allow predicting its behavior in vitro. The high pressure liquid chromatography results revealed high drug content entrapment in the microemulsion droplet. Finally, the amphotericin B-microemulsion in vitro susceptibility test showed high activity against Candida strains and a low toxicity profile against red blood cells when compared to Fungizone®. The physicochemical characterization of the microemulsion demonstrated that its characteristics are compatible with the topical ocular route, making it eligible for consideration as a new and interesting amphotericin B-deliverydosage form to be used as eye drop formulation.

  3. Photoionization of oxidized coenzyme Q in microemulsion: laser flash photolysis study in biomembrane-like system.

    Science.gov (United States)

    Li, Kun; Wang, Mei; Wang, Jin; Zhu, Rongrong; Sun, Dongmei; Sun, Xiaoyu; Wang, Shi-Long

    2013-01-01

    Photoexcitation to generate triplet state has been proved to be the main photoreaction in homogeneous system for many benzoquinone derivatives, including oxidized coenzyme Q (CoQ) and its analogs. In the present study, microemulsion of CoQ, a heterogeneous system, is employed to mimic the distribution of CoQ in biomembrane. The photochemistry of CoQ(10) in microemulsion and cyclohexane is investigated and compared using laser flash photolysis and results show that CoQ(10) undergoes photoionization via a monophotonic process to generate radical cation of CoQ(10) in microemulsion and photoexcitation to generate excited triplet state in cyclohexane. Meanwhile, photoreactions of duroquinone (DQ) and CoQ(0) in microemulsion are also investigated to analyze the influence of molecular structure on the photochemistry of benzoquinone derivatives in microemulsion. Results suggest that photoexcitation, which is followed by excited state-involved hydrogen-abstraction reaction, is the main photoreaction for DQ and CoQ(0) in microemulsion. However, photoexcited CoQ(0) also leads to the formation of hydrated electrons. The isoprenoid side chain-involved high resonance stabilization is proposed to explain the difference in photoreactions of CoQ(0) and CoQ(10) in microemulsion. Considering that microemulsion is close to biomembrane system, its photoionization in microemulsion may be helpful to understand the real photochemistry of biological quinones in biomembrane system. © 2012 Tongji University. Photochemistry and Photobiology © 2012 The American Society of Photobiology.

  4. Novel microemulsion-based gel formulation of tazarotene for therapy of acne.

    Science.gov (United States)

    Patel, Mrunali Rashmin; Patel, Rashmin Bharatbhai; Parikh, Jolly R; Patel, Bharat G

    2016-12-01

    The objective of this study was to develop and evaluate a novel microemulsion based gel formulation containing tazarotene for targeted topical therapy of acne. Psudoternary phase diagrams were constructed to obtain the concentration range of oil, surfactant, and co-surfactant for microemulsion formation. The optimized microemulsion formulation containing 0.05% tazarotene was formulated by spontaneous microemulsification method consisting of 10% Labrafac CC, mixed emulsifiers 15% Labrasol-Cremophor-RH 40 (1:1), 15% Capmul MCM, and 60% distilled water (w/w) as an external phase. All plain and tazarotene-loaded microemulsions were clear and showed physicochemical parameters for desired topical delivery and stability. The permeation profiles of tazarotene through rat skin from optimized microemulsion formulation followed the Higuchi model for controlled permeation. Microemulsion-based gel was prepared by incorporating Carbopol®971P NF in optimized microemulsion formulation having suitable skin permeation rate and skin uptake. Microemulsion-based gel showed desired physicochemical parameters and demonstrated advantage over marketed formulation in improving the skin tolerability of tazarotene indicating its potential in improving its topical delivery. The developed microemulsion-based gel may be a potential drug delivery vehicle for targeted topical delivery of tazarotene in the treatment of acne.

  5. Microemulsion for simultaneous transdermal delivery of benzocaine and indomethacin: in vitro and in vivo evaluation.

    Science.gov (United States)

    El Maghraby, Gamal M; Arafa, Mona F; Osman, Mohamed A

    2014-12-01

    This study investigated simultaneous transdermal delivery of indomethacin and benzocaine from microemulsion. Eucalyptus oil based microemulsion was used with Tween 80 and ethanol being employed as surfactant and cosurfactant, respectively. A microemulsion formulation comprising eucalyptus oil, polyoxyethylene sorbitan momooleate (Tween 80), ethanol and water (20:30:30:20) was selected. Indomethacin (1% w/w) and benzocaine (20% w/w) were incorporated separately or combined into this formulation before in vitro and in vivo evaluation. Application of indomethacin microemulsion enhanced the transdermal flux and reduced the lag time compared to saturated aqueous control. The same trend was evident for benzocaine microemulsion. Simultaneous application of the two drugs in microemulsion provided similar enhancement pattern. The in vivo evaluation employed the pinprick method and revealed rapid anesthesia after application of benzocaine microemulsion with the onset being 10 min and the action lasting for 50 min. For indomethacin microemulsion, the analgesic effect was recorded after 34.5 min and lasted for 70.5 min. Simultaneous application of benzocaine and indomethacin provided synergistic effect. The onset of action was achieved after 10 min and lasted for 95 min. The study highlighted the potential of microemulsion formulation in simultaneous transdermal delivery of two drugs.

  6. Analysis and antibacterial activity of Nigella sativa essential oil formulated in microemulsion system.

    Science.gov (United States)

    Shaaban, Hamdy A; Sadek, Zainab; Edris, Amr E; Saad-Hussein, Amal

    2015-01-01

    The Essential oil (EO) of Nigella sativa (black cumin) was extracted from the crude oil and the volatile constituents were characterized using gas chromatographic analysis. The EO was formulated in water-based microemulsion system and its antibacterial activity against six pathogenic bacteria was evaluated using the agar well diffusion method. This activity was compared with two other well known biologically active natural and synthetic antimicrobials namely eugenol and Ceftriaxone(®). Results showed that N. sativa EO microemulsion was highly effective against S. aureus, B. cereus and S. typhimurium even at the lowest tested concentration of that EO in the microemulsion (100.0 μg/well). Interestingly, the EO microemulsion showed higher antibacterial activity than Ceftriaxone solution against S. typhimurium at 400.0 μg/well and almost comparable activity against E. coli at 500.0 μg/well. No activity was detected for the EO microemulsion against L. monocytogenes and P. aeruginosa. Eugenol which was also formulated in microemulsion was less effective than N. sativa EO microemulsion except against P. aeruginosa. The synthetic antibiotic (Ceftriaxone) was effective against most of the six tested bacterial strains. This work is the first report revealing the formulation of N. sativa EO in microemulsion system and investigating its antibacterial activity. The results may offer potential application of that water-based microemulsion in controlling the prevalence of some pathogenic bacteria.

  7. Reversible flexible structural changes in multidimensional MOFs by guest molecules (I{sub 2}, NH{sub 3}) and thermal stimulation

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yang; Li, Libo; Yang, Jiangfeng; Wang, Shuang; Li, Jinping, E-mail: Jpli211@hotmail.com

    2015-03-15

    Three metal–organic frameworks (MOFs), [Cu(INA){sub 2}], [Cu(INA){sub 2}I{sub 2}] and [Cu(INA){sub 2}(H{sub 2}O){sub 2}(NH{sub 3}){sub 2}], were synthesized with 3D, 2D, and 0D structures, respectively. Reversible flexible structural changes of these MOFs were reported. Through high temperature (60–100 °C) stimulation of I{sub 2} or ambient temperature stimulation of NH{sub 3}, [Cu(INA){sub 2}] (3D) converted to [Cu(INA){sub 2}I{sub 2}] (2D) and [Cu(INA){sub 2}(H{sub 2}O){sub 2}(NH{sub 3}){sub 2}] (0D); as the temperature increased to 150 °C, the MOFs changed back to their original form. In this way, this 3D MOF has potential application in the capture of I{sub 2} and NH{sub 3} from polluted water and air. XRD, TGA, SEM, NH{sub 3}-TPD, and the measurement of gas adsorption were used to describe the changes in processes regarding the structure, morphology, and properties. - Graphical abstract: Through I{sub 2}, NH{sub 3} molecules and thermal stimulation, the three MOFs can achieve reversible flexible structural changes. Different methods were used to prove the flexible reversible changes. - Highlights: • [Cu(INA){sub 2}] can flexible transform to [Cu(INA){sub 2}I{sub 2}] and [Cu(INA){sub 2}(H{sub 2}O){sub 2}(NH{sub 3}){sub 2}] by adsorbing I{sub 2} or NH{sub 3}. • The reversible flexible transformation related to material source, temperature and concentration. • Potential applications for the capture of I{sub 2} and NH{sub 3} from polluted water or air.

  8. Pt Combustion Catalysts Prepared from W/O Microemulsions

    Czech Academy of Sciences Publication Activity Database

    Rymeš, Jan; Ehret, G.; Hilaire, L.; Jirátová, Květa

    2002-01-01

    Roč. 143, - (2002), s. 121-129 ISSN 0167-2991. [International Symposium Scientific Bases for the Preparation of Heterogeneous Catalysts /8./. Louvain-la-Neuve, 09.09.2002-12.09.2002] R&D Projects: GA AV ČR IAA4072904 Keywords : combustion catalysts * microemulsion s Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 3.468, year: 2002

  9. Anesthetic Properties of a Propofol Microemulsion in Dogs

    Science.gov (United States)

    Morey, Timothy E.; Modell, Jerome H.; Shekhawat, Dushyant; Shah, Dinesh O.; Klatt, Brian; Thomas, George P.; Kero, Frank A.; Booth, Matthew M.; Dennis, Donn M.

    2010-01-01

    Microemulsions of propofol with nanometer droplet diameter are alternative agents to soybean macroemulsions to induce anesthesia and may have important advantages. We used a propofol (10 mg/ml) microemulsion (particle diameter 24.5±0.5 nm) and a commercial macroemulsion to induce anesthesia in dogs (n=10) using a randomized, crossover design separated by a 7 day rest interval. Endpoints were loss of leg withdrawal following a toe pinch and changes in vital signs. Venous blood samples were acquired at multiple times to measure plasma propofol concentrations and indices of erythrocytes, leukocytes and coagulation. All dogs were rendered insensitive to pain followed by successful recovery without noticeable complications. Comparing indices between microemulsion and macroemulsion formulations, no differences were noted with respect to dose (10.3±1.2 and 9.7±1.6 mg/kg, respectively, P=0.39), time to induction (1.0±0.1 and 1.0±0.2 min, P=0.39), time to recovery (17.4±4.6 and 18.2±3.8 min, P=0.70), heart rate (P=0.62), blood pressure (P=0.81), respiratory rate (P=0.60), hemogram parameters, prothrombin time (P=0.89), activated partial thromboplastin time (P=0.76), fibrinogen concentration (P=0.52), platelet concentration (P=0.55), or plasma propofol concentrations (P=0.20). Induction with a propofol microemulsion or macroemulsion did not significantly vary to with respect to vital signs, the hemogram, clotting parameters, and plasma propofol concentrations. PMID:17000798

  10. Room-temperature synthesis of MnMoO{sub 4}{center_dot}H{sub 2}O nanorods by the microemulsion-based method and its photocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Mi Yan; Huang Zaiyin; Zhou Zeguang; Hu Feilong; Meng Qiufeng [College of Chemistry and Ecological Engineering, Guangxi University for Nationalities, Nanning 530006 (China)], E-mail: hzy210@yahoo.cn

    2009-09-01

    Manganese molybdate hydrates (MnMoO{sub 4}{center_dot}H{sub 2}O) nanorods have been synthesized at room temperature by a facile water-in-oil reverse microemulsion method. This technique was carried out in the reverse microemulsion of OP-10 (Polyoxyethylene octylphenol ether)-n-octanol-water-cyclohexane with a water/surfactant molar ratio {omega} = 10. Field-emission scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed that the diameters of these formed nanorods about 70 nm and lengthe up to 4 {mu}m, respectively. High-resolution transmission electron microscopy (HRTEM) results showed that each nanorod was formed by serveral nanobelts which are stacked by a layer-by-layer process. These unique nanorods demonstrate good photocatalytic properties.

  11. The lesser known challenge of climate change: thermal variance and sex-reversal in vertebrates with temperature-dependent sex determination.

    Directory of Open Access Journals (Sweden)

    Jennifer L Neuwald

    Full Text Available Climate change is expected to disrupt biological systems. Particularly susceptible are species with temperature-dependent sex determination (TSD, as in many reptiles. While the potentially devastating effect of rising mean temperatures on sex ratios in TSD species is appreciated, the consequences of increased thermal variance predicted to accompany climate change remain obscure. Surprisingly, no study has tested if the effect of thermal variance around high-temperatures (which are particularly relevant given climate change predictions has the same or opposite effects as around lower temperatures. Here we show that sex ratios of the painted turtle (Chrysemys picta were reversed as fluctuations increased around low and high unisexual mean-temperatures. Unexpectedly, the developmental and sexual responses around female-producing temperatures were decoupled in a more complex manner than around male-producing values. Our novel observations are not fully explained by existing ecological models of development and sex determination, and provide strong evidence that thermal fluctuations are critical for shaping the biological outcomes of climate change.

  12. Optimization of minoxidil microemulsions using fractional factorial design approach.

    Science.gov (United States)

    Jaipakdee, Napaphak; Limpongsa, Ekapol; Pongjanyakul, Thaned

    2016-01-01

    The objective of this study was to apply fractional factorial and multi-response optimization designs using desirability function approach for developing topical microemulsions. Minoxidil (MX) was used as a model drug. Limonene was used as an oil phase. Based on solubility, Tween 20 and caprylocaproyl polyoxyl-8 glycerides were selected as surfactants, propylene glycol and ethanol were selected as co-solvent in aqueous phase. Experiments were performed according to a two-level fractional factorial design to evaluate the effects of independent variables: Tween 20 concentration in surfactant system (X1), surfactant concentration (X2), ethanol concentration in co-solvent system (X3), limonene concentration (X4) on MX solubility (Y1), permeation flux (Y2), lag time (Y3), deposition (Y4) of MX microemulsions. It was found that Y1 increased with increasing X3 and decreasing X2, X4; whereas Y2 increased with decreasing X1, X2 and increasing X3. While Y3 was not affected by these variables, Y4 increased with decreasing X1, X2. Three regression equations were obtained and calculated for predicted values of responses Y1, Y2 and Y4. The predicted values matched experimental values reasonably well with high determination coefficient. By using optimal desirability function, optimized microemulsion demonstrating the highest MX solubility, permeation flux and skin deposition was confirmed as low level of X1, X2 and X4 but high level of X3.

  13. Synthesis and characterization of silver nanoparticles in AOT microemulsion system

    International Nuclear Information System (INIS)

    Zhang Wanzhong; Qiao Xueliang; Chen Jianguo

    2006-01-01

    Colloidal silver nanoparticles have been synthesized in water-in-oil microemulsion using silver nitrate solubilized in the water core of one microemulsion as source of silver ions, hydrazine hydrate solubilized in the water core of another microemulsion as reducing agent, dodecane as the oil phase, sodium bis(2-ethylhexyl) sulfosuccinate (AOT) as the surfactant. The UV-vis absorption spectra and transmission electron microscopy (TEM) have been used to trace the growth process and elucidate the structure of the silver nanoparticles. UV-vis spectra show that the Ag 4 + intermediates formed at early stages of the reaction and then the clusters grow or aggregate to larger nanoparticles. TEM micrographs confirm that the silver nanoparticles are all spherical. The resulting particles have a very narrow size distribution. Meanwhile, the diameter size of the particles is so small that the smallest mean diameter is only 1.6nm. IR results show that the surfactant molecules are strongly adsorbed on the surface of silver particles through a coordination bond between the silver atom and the sulfonic group of AOT molecules, which endows the particles with a good stability in oil solvents. As dodecane is used as oil solvent to prepare silver nanoparticles, the formed nano-silver sol is almost nontoxic. As a result, the silver nanoparticles need not be separated from the reaction solution and the silver sol may be directly used in antibacterial fields

  14. Formulation development and in vitro evaluation of solidified self-microemulsion in the form of tablet containing atorvastatin calcium.

    Science.gov (United States)

    Ali, Kazi Asraf; Mukherjee, Biswajit; Bandyopadhyay, Amal Kumar

    2013-11-01

    The objective of our present study was to prepare solid self-microemulsion in the form of tablet of a poorly water soluble drug, Atorvastatin calcium (ATNC) to increase the solubility, dissolution rate, and minimize the hazards experienced from liquid emulsions. Self-microemulsifying ATNC tablet was formulated mainly by using self-emulsifying base, solidifying agent silicon dioxide and sodium starch glycolate as tablet disintegrant. Self-emulsifying base containing Transcutol P, Gelucire 44/14, and Lutrol F68 with their ratios in the formulation, were best selected by solubility study and ternary phase diagram in different vehicles. Particle size of microemulsion from tablet, physical parameters of the tablet and drug content has been checked. In vitro drug release rate has been carried out in phosphate buffer medium (pH 6.8). Physicochemical characterization of the drug in the optimized formulation has been performed to check drug-excipient incompatibility, if any. Average particle diameter of the emulsions formed from the tablet was found to be below 100 nm in case of formulation F4 and F5, which indicated microemulsions has been formed. In vitro drug release from the formulations F3, F4, and F5 was found to be >90%, indicated the enhancement of solubility of ATNC compared to parent drug. Differential thermal analysis (DTA), Powder X-ray Diffraction (X-RD) and Fourier transform infra red (FTIR) study proved the identity of the drug in the optimized formulation. The tablet form of self-microemulsifying (SME) drug delivery is good for solubility enhancement.

  15. Heteropolytungstate nanoparticles: Microemulsion-mediated preparation and investigation of their catalytic activity in the epoxidation of olefins

    Energy Technology Data Exchange (ETDEWEB)

    Masteri-Farahani, M., E-mail: mfarahany@yahoo.com; Ghorbani, M.

    2016-04-15

    Highlights: • Keggin type Q{sub 3}PW{sub 12}O{sub 40} nanoparticles were synthesized by using microemulsion system. • The nanoparticles have uniform size of about 25 nm and spherical morphologies. • The prepared nanoparticles act as reusable catalyst in the epoxidation of olefins with H{sub 2}O{sub 2}. - Abstract: Keggin type Q{sub 3}PW{sub 12}O{sub 40} nanoparticles (Q = cetyltrimethylammonium cation) were synthesized in water-in-oil (w/o) microemulsion consisted of water/cetyltrimethylammonium bromide/n-butanol/isooctane. Reaction of Na{sub 2}WO{sub 4}, Na{sub 2}HPO{sub 4} and hydrochloric acid within water containing nanoreactors of reverse micelles resulted in the preparation of Q{sub 3}PW{sub 12}O{sub 40} nanoparticles. The resultant nanoparticles were analyzed by physicochemical methods such as FT-IR spectroscopy, X-ray diffraction, energy-dispersive X-ray analysis, thermogravimetric analyses (TGA-DTA), scanning and transmission electron microscopy and atomic force microscopy which show nearly uniform spherical nanoparticles with size of about 15 nm. Finally, catalytic activity of the Q{sub 3}PW{sub 12}O{sub 40} nanoparticles was examined in the epoxidation of olefins with H{sub 2}O{sub 2}. The prepared nanoparticles acted as recoverable and reusable catalyst in the epoxidation of olefins with H{sub 2}O{sub 2}.

  16. Influence of microemulsion chirality on chromatographic figures of merit in EKC: results with novel three-chiral-component microemulsions and comparison with one- and two-chiral-component microemulsions.

    Science.gov (United States)

    Kahle, Kimberly A; Foley, Joe P

    2007-08-01

    Novel microemulsion formulations containing all chiral components are described for the enantioseparation of six pairs of pharmaceutical enantiomers (atenolol, ephedrine, metoprolol, N-methyl ephedrine, pseudoephedrine, and synephrine). The chiral surfactant dodecoxycarbonylvaline (DDCV, R- and S-), the chiral cosurfactant S-2-hexanol, and the chiral oil diethyl tartrate (R- and S-) were combined to create four different chiral microemulsions, three of which were stable. Results obtained for enantioselectivity, efficiency, and resolution were compared for the triple-chirality systems and the single-chirality system that contained chiral surfactant only. Improvements in enantioselectivity and resolution were achieved by simultaneously incorporating three chiral components into the aggregate. The one-chiral-component microemulsion provided better efficiencies. Enantioselective synergies were identified for the three-chiral-component nanodroplets using a thermodynamic model. Additionally, two types of dual-chirality systems, chiral surfactant/chiral cosurfactant and chiral surfactant/chiral oil, were examined in terms of chromatographic figures of merit, with the former providing much better resolution. The two varieties of two-chiral-component microemulsions gave similar values for enantioselectivity and efficiency. Lastly, the microemulsion formulations were divided into categories based on the number of chiral microemulsion reagents and the average results for each pair of enantiomers were analyzed for trends. In general, enantioselectivity and resolution were enhanced while efficiency was decreased as more chiral components were used to create the pseudostationary phase (PSP).

  17. [Exploration of one-step preparation of Ganoderma lucidum multicomponent microemulsion].

    Science.gov (United States)

    He, Jun-Jie; Chen, Yan; Du, Meng; Cao, Wei; Yuan, Ling; Zheng, Li-Yan

    2013-03-01

    To explore one-step method for the preparation of Ganoderma lucidum multicomponent microemulsion, according to the dissolution characteristics of triterpenes and polysaccharides in Ganoderma lucidum, formulation of the microemulsion was optimized. The optimal blank microemulsion was used as a solvent to sonicate the Ganoderma lucidum powder to prepare the multicomponent microemulsion, besides, its physicochemical properties were compared with the microemulsion made by conventional method. The results showed that the multicomponent microemulsion was characterized as (43.32 +/- 6.82) nm in size, 0.173 +/- 0.025 in polydispersity index (PDI) and -(3.98 +/- 0.82) mV in zeta potential. The contents of Ganoderma lucidum triterpenes and polysaccharides were (5.95 +/- 0.32) and (7.58 +/- 0.44) mg x mL(-1), respectively. Sonicating Ganoderma lucidum powder by blank microemulsion could prepare the multicomponent microemulsion. Compared with the conventional method, this method is simple and low cost, which is suitable for industrial production.

  18. Novel Fluorescent Microemulsion: Probing Properties, Investigating Mechanism, and Unveiling Potential Application.

    Science.gov (United States)

    Hou, Mengna; Dang, Leping; Liu, Tiankuo; Guo, Yun; Wang, Zhanzhong

    2017-08-09

    Nanoscale microemulsions have been utilized as delivery carriers for nutraceuticals and active biological drugs. Herein, we designed and synthesized a novel oil in water (O/W) fluorescent microemulsion based on isoamyl acetate, polyoxyethylene castor oil EL (CrEL), and water. The microemulsion emitted bright blue fluorescence, thus exhibiting its potential for active drug detection with label-free strategy. The microemulsion exhibited excitation-dependent emission and distinct red shift with longer excitation wavelengths. Lifetime and quantum yield of fluorescent microemulsion were 2.831 ns and 5.0%, respectively. An excellent fluorescent stability of the microemulsion was confirmed by altering pH, ionic strength, temperature, and time. Moreover, we proposed a probable mechanism of fluorochromic phenomenon, in connection with the aromatic ring structure of polyoxyethylene ether substituent in CrEL. Based on our findings, we concluded that this new fluorescent microemulsion is a promising drug carrier that can facilitate active drug detection with a label-free strategy. Although further research is required to understand the exact mechanism behind its fluorescence property, this work provided valuable guidance to develop new biosensors based on fluorescent microemulsion.

  19. Pulsed-laser studies on the free-radical polymerization kinetics of styrene in microemulsion

    NARCIS (Netherlands)

    Manders, L.G.; Herk, van A.M.; German, A.L.; Sarnecki, J.; Schomäcker, R.; Schweer, J.

    1993-01-01

    A mean value of 339 L mol-1 s-1 was obtained for the propagation const. derived from pulsed-laser polymn. (PLP) of styrene in aq. AOT microemulsions. For accurate detns., simulations accounting for the esp. high radical concn. after the laser pulse in microemulsions were recommended. PLP with

  20. Formulation and Physical Characterization of Microemulsions Based Carboxymethyl Cellulose as Vitamin C Carrier

    International Nuclear Information System (INIS)

    Suria Ramli; Safiah Mohd Jaafar; Muhd Asri Abd Sisak; Norhidayu Zainuddin; Irman Abdul Rahman

    2015-01-01

    The main purpose of this research is to develop a cellulose derivative based microemulsion for transdermal delivery system. In this research, cellulose derivative used is carboxymethyl cellulose (CMC) that was converted from cellulose by etherification reaction and analysed by FTIR instrument. The degree of substitution (DS) for carboxymethyl cellulose is 0.492. Microemulsion system consists of oleic acid as oil phase, Tween 20 as surfactant and propylene glycol as co-surfactant. The active ingredient used in this system is vitamin C. Determination of microemulsion area in the ternary phase diagram was done by titration method. From the result, microemulsion system with surfactant/co-surfactant ratio (K m =3:1) produced the largest surface area in the ternary phase diagram. Microemulsions with and without vitamin C and CMC were characterized using dynamic light scattering (DLS), electrical conductivity and rheometer. For size particle analysis, system without vitamin C and CMC have microemulsion droplet size between 20-200 nm. Based on the electrical conductivity and viscosity test, phase transition occurred in the microemulsion system from water-in-oil (w/o) to bicontinuous phase at 20 wt. % water percentage. The stability test showed microemulsion systems with the percentage of water up to 30 wt. % were stable at temperatures 4, 25 and 40 degree Celsius upon three weeks storage. (author)

  1. Investigation on the thermal properties of new thermo-reversible networks based on poly(vinyl furfural and multifunctional maleimide compounds

    Directory of Open Access Journals (Sweden)

    C. Gaina

    2012-02-01

    Full Text Available New thermo-reversible networks were obtained from poly(vinyl furfural and multifunctional maleimide monomers by Diels-Alder (DA and retro-DA reactions. The poly(vinyl furfural having acetalization degree of 15 and 25% were obtained by the acid-catalyzed homogenous acetalization of poly(vinyl alcohol with 2-furfural in a nonaqueous media. The thermal and viscoelastic behaviour of the cross-linked materials have been studied via differential scanning calorimetry, dynamic mechanical analysis and thermogravimetric analysis. The networks exhibit considerable swelling in those organic solvents that dissolve both poly(vinyl furfural and bismaleimides; by heating in aprotic dipolar solvents at 150°C, they become soluble.

  2. Synthesis of Thermally Switchable Chromatographic Materials with Immobilized Ti4+ for Enrichment of Phosphopeptides by Reversible Addition Fragmentation Chain Transfer Polymerization

    Science.gov (United States)

    Wang, Di; Cao, Zhihan; Pang, Xinzhu; Deng, Yulin; Li, Bo; Dai, Rongji

    2018-01-01

    Reversible phosphorylation of proteins is one of the most crucial types of post-translational modifications (PTMs). And it shows significant work in diversified biological processes. However, the separation technology of phosphorylated peptides is still an analytical challenge in phosphoproteomics, because phosphopeptides are alway in low stoichiometry. Thus, enrichment of phosphopeptides before detection is indispensable. In this study, a novel temperature regulated separation protocol was developed. Silica@p (NIPAAm-co-IPPA)-Ti4+, a new Ti(IV)-IMAC (Immobilized Metal Affinity chromatography) materials was synthesized by reversible addition fragmentation chain transfer polymerization (RAFT). By the unique thermally responsive properties of poly(N-isopropylacrylamide) (PNIPAAm), the captured phosphorylated peptides could be released by changing temperature only without applying any other eluant which could damage the phosphopeptides. We employed isopropanol phosphonic acid (IPPA) as an IMAC ligand for the immobilization of Ti(IV) which could increase the specific adsorption of phosphopeptides. The enrichment and release properties were examined by treatment with pyridoxal 5’-phosphate (PLP) and casein phosphopeptides (CPP). Two phosphorylated compounds above have temperature-stimulated binding to Ti4+. Finally, silica@p (NIPAAm-co-IPPA)-Ti4+ was successfully employed in pretreatment of phosphopeptides in a tryptic digest of a-casein and human serum albumin (HSA). The results indicated a great potential of this new temperature-responsive material in phosphoproteomics study.

  3. Effect of surfactant chain length on drug release kinetics from microemulsion-laden contact lenses.

    Science.gov (United States)

    Maulvi, Furqan A; Desai, Ankita R; Choksi, Harsh H; Patil, Rahul J; Ranch, Ketan M; Vyas, Bhavin A; Shah, Dinesh O

    2017-05-30

    The effect of surfactant chain lengths [sodium caprylate (C 8 ), Tween 20 (C 12 ), Tween 80 (C 18 )] and the molecular weight of block copolymers [Pluronic F68 and Pluronic F 127] were studied to determine the stability of the microemulsion and its effect on release kinetics from cyclosporine-loaded microemulsion-laden hydrogel contact lenses in this work. Globule size and dilution tests (transmittance) suggested that the stability of the microemulsion increases with increase in the carbon chain lengths of surfactants and the molecular weight of pluronics. The optical transmittance of direct drug-laden contact lenses [DL-100] was low due to the precipitation of hydrophobic drugs in the lenses, while in microemulsion-laden lenses, the transmittance was improved when stability of the microemulsion was achieved. The results of in vitro release kinetics revealed that drug release was sustained to a greater extent as the stability of microemulsion was improved as well. This was evident in batch PF127-T80, which showed sustained release for 15days in comparison to batch DL-100, which showed release up to 7days. An in vivo drug release study in rabbit tear fluid showed significant increase in mean residence time (MRT) and area under curve (AUC) with PF-127-T80 lenses (stable microemulsion) in comparison to PF-68-SC lenses (unstable microemulsion) and DL-100 lenses. This study revealed the correlation between the stability of microemulsion and the release kinetics of drugs from contact lenses. Thus, it was inferred that the stable microemulsion batches sustained the release of hydrophobic drugs, such as cyclosporine from contact lenses for an extended period of time without altering critical lens properties. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. [Optimize preparation of compound licorice microemulsion with D-optimal design].

    Science.gov (United States)

    Ma, Shu-Wei; Wang, Yong-Jie; Chen, Cheng; Qiu, Yue; Wu, Qing

    2018-03-01

    In order to increase the solubility of essential oil in compound licorice microemulsion and improve the efficacy of the decoction for treating chronic eczema, this experiment intends to prepare the decoction into microemulsion. The essential oil was used as the oil phase of the microemulsion and the extract was used as the water phase. Then the microemulsion area and maximum ratio of water capacity was obtained by plotting pseudo-ternary phase diagram, to determine the appropriate types of surfactant and cosurfactant, and Km value-the mass ratio between surfactant and cosurfactant. With particle size and skin retention of active ingredients as the index, microemulsion prescription was optimized by D-optimal design method, to investigate the in vitro release behavior of the optimized prescription. The results showed that the microemulsion was optimal with tween-80 as the surfactant and anhydrous ethanol as the cosurfactant. When the Km value was 1, the area of the microemulsion region was largest while when the concentration of extract was 0.5 g·mL⁻¹, it had lowest effect on the particle size distribution of microemulsion. The final optimized formulation was as follows: 9.4% tween-80, 9.4% anhydrous ethanol, 1.0% peppermint oil and 80.2% 0.5 g·mL⁻¹ extract. The microemulsion prepared under these conditions had a small viscosity, good stability and high skin retention of drug; in vitro release experiment showed that microemulsion had a sustained-release effect on glycyrrhizic acid and liquiritin, basically achieving the expected purpose of the project. Copyright© by the Chinese Pharmaceutical Association.

  5. Thalamic VPM nucleus in the behaving monkey. III. Effects of reversible inactivation by lidocaine on thermal and mechanical discrimination.

    Science.gov (United States)

    Duncan, G H; Bushnell, M C; Oliveras, J L; Bastrash, N; Tremblay, N

    1993-11-01

    1. The present study evaluates the necessity of the ventroposterior medial thalamic nucleus (VPM) for discrimination of the intensity of noxious heating, innocuous cooling, and innocuous tactile (airpuff) stimulation of the maxillary skin. 2. Two rhesus monkeys were trained to detect small differences (Lidocaine hydrochloride (2%) was microinjected into regions of thalamus where single-unit recordings had identified neuronal responses to the noxious heating and/or cooling stimuli. The effectiveness of the anesthetic blockade was monitored by multiunit recordings using microelectrodes positioned 1-3 mm from the orifice of the injection cannula. The monkey's ability to detect near-threshold changes in stimulus intensity was compared before and after each injection. 3. During six experimental sessions, single injections of 1-4 microliters lidocaine near the dorsomedial border of VPM did not significantly alter the monkey's ability to detect small changes in the intensity of noxious heat, cool, airpuff, or visual stimuli despite neurophysiological evidence that spontaneous neuronal activity was blocked within parts of VPM. 4. During three experiments, dual simultaneous microinjections of lidocaine (delivered through 2 microcannulae separated by approximately 1 mm) resulted in profound deficits in noxious heat discrimination, with lesser deficits in cool and airpuff discrimination; visual discrimination was never altered. Monitoring of adjacent microelectrodes revealed that although activity ventral to the injection sites was blocked, activity in medial thalamic nuclei, implicated in nociceptive processing, was probably not altered by these injections. 5. These data suggest that VPM is important for the perception of noxious and innocuous thermal stimuli as well as for the perception of tactile stimuli. However, considering the ineffectiveness of small single microinjections of lidocaine, it appears that some critical proportion of VPM must be inactivated to disrupt

  6. Structural and thermal investigations of an amorphous GaSe9 alloy using EXAFS, cumulant expansion, and reverse Monte Carlo simulations

    International Nuclear Information System (INIS)

    Siqueira, M. C.; Maia, R. N. A.; Araujo, R. M. T.; Machado, K. D.; Stolf, S. F.

    2015-01-01

    In this article, we investigated structural and thermal properties of an amorphous alloy of the Ga–Se system. The amorphous GaSe 9 alloy was produced by mechanical alloying and it was studied using EXAFS spectroscopy and cumulant expansion method. We also made reverse Monte Carlo simulations using the total structure factor S(K) obtained from x-ray diffraction and the EXAFS χ(k) oscillations on Se and Ga K edges as input data. Several parameters, such as average coordination numbers and interatomic distances, structural and thermal disorders, asymmetry of the partial distribution functions g ij (r), and Einstein and Debye temperatures, were determined. The g ij E (r) functions were reconstructed from the cumulants C 1 , C 2 , and C 3 obtained from the Einstein model, and they were compared to the g ij RMC (r) functions obtained from the simulations. The simulations also furnished the partial bond angle distribution functions Θ ijℓ (cosθ), which describe the angular distribution of bonds between first neighbors, and give information about the kind of structural units present in the alloy

  7. Reversible bulk-phase change of anthroyl compounds for photopatterning based on photodimerization in the molten state and thermal back reaction.

    Science.gov (United States)

    Kihara, Hideyuki; Yoshida, Masaru

    2013-04-10

    As new organic materials for rewritable photopatterning, 2-anthroyl and 9-anthroyl ester compounds were synthesized. Their bulk-phase changes (we use "bulk-phase change" as complete phase change in a mass of a material neither in a surface nor in a small quantity in this study) triggered by photodimerization under melting conditions (melt-photodimerization) and subsequent thermal back reactions were investigated. All the anthroyl compounds exhibited melting points lower than ca. 160 °C, and they were nearly quantitatively converted to the corresponding photodimers by UV irradiation at temperatures of ∼5 °C higher than their respective melting points. We found that there were two kinds of bulk-phase change behaviors through the photoreaction. Two of the anthroyl compounds remained isotropic and lost fluidity during the melt-photodimerization. The obtained photodimers exhibited robust solid-state amorphous phases at room temperature. In contrast, the other three anthroyl compounds showed crystallization during the melt-photodimerization. The resulting photodimers changed from isotropic to crystalline phases, even at high temperature. Various experiments revealed that the bulk phase of the photodimers was affected not by the existence of regioisomers but by their fluidity at the photoirradiation temperature. The latter three photodimers retained enough fluidity, reflecting their high molecular mobilities at the photoirradiation temperature at which the isothermal crystallization occurred. The other two products were not able to crystallize due to low fluidity, resulting in amorphous phases. We also found that all the photodimers reverted to the corresponding monomers by thermal back reaction and recovered their initial photochemical and thermal properties. Using these reversible bulk-phase changes of the anthroyl compounds, we successfully demonstrated rewritable photopatterning in not only negative images but also positive ones, based on the optical contrast

  8. Analysis of polyethoxylated surfactants in microemulsion-oil-water systems III. Fractionation and partitioning of polyethoxylated alcohol surfactants

    International Nuclear Information System (INIS)

    Marquez, N.; Bravo, B.; Ysambertt, F.; Chavez, G.; Subero, N.; Salager, J.L.

    2002-01-01

    Oligomer distribution of polyethoxylated alcohol and polyethoxylated nonylphenol surfactants is studied by normal and reverse-phase high performance liquid chromatography (HPLC). A RP8 column is able to efficiently separate these surfactants according to their alkyl chain (lipophilic) group, while silica and amino columns separate them according to their polyether chain length (hydrophilic group). Polyethoxylated alcohol and polyethoxylated nonylphenol oligomers selectively partition between the microemulsion-oil-water phases of a Winsor III system. Partitioning of these oligomers was analyzed by HPLC with RI detection. The logarithm of the partition coefficient between the water and oil linearly increases with the number of ethylene oxide groups per molecule of oligomer. For a same ethoxylation degree, the partition coefficient of a polyethoxylated tridecanol is found to be higher than the one of the corresponding nonylphenol specie. On the other hand, a polyethoxylated nonylphenol exhibits a higher solubilization than the matching polyethoxylated alcohol

  9. Electrochemical capacitance of nanostructured ruthenium-doped tin oxide Sn1- x Ru x O2 by the microemulsion method

    Science.gov (United States)

    Saraswathy, Ramanathan

    2017-12-01

    Synthesis of nanostructured Ru-doped SnO2 was successfully carried out using the reverse microemulsion method. The phase purity and the crystallite size were analyzed by XRD. The surface morphology and the microstructure of synthesized nanoparticles were analyzed by SEM and TEM. The vibration mode of nanoparticles was investigated using FTIR and Raman studies. The electrochemical behavior of the Ru-doped SnO2 electrode was evaluated in a 0.1 mol/L Na2SO4 solution using cyclic voltammetry. The 5% Ru-doped SnO2 electrode exhibited a high specific capacitance of 535.6 F/g at a scan rate 20 mV/s, possessing good conductivity as well as the electrocycling stability. The Ru-doped SnO2 composite shows excellent electrochemical properties, suggesting that this composite is a promising material for supercapacitors.

  10. Preparation of submicrometer monodispersed magnetic silica particles using a novel water in oil microemulsion: properties and application for enzyme immobilization.

    Science.gov (United States)

    Tuttolomondo, Maria Victoria; Villanueva, Maria Emilia; Alvarez, Gisela Solange; Desimone, Martín Federico; Díaz, Luis Eduardo

    2013-10-01

    The synthesis of monodispersed magnetic silica nanoparticles (MSN) is described using a water-in-oil reverse microemulsion system that does not require the use of co-surfactants. Sodium silicate, Tween 20 as a neutral surfactant and 1-butanol as the organic phase were used. There are several advantages of the proposed method including a saturation magnetization value of 10 emu/g for the particles obtained, uniformity of size and that they are easily functionalized to bind urease covalently. Moreover, the intra-day, inter-day and long-term stability results confirm that the procedure was successful and the enzyme-linked MSNs were stable over repeated uses and storage retaining more than 75% activity after 4 months.

  11. Microemulsion extrusion technique: a new method to produce lipid nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Jesus, Marcelo Bispo de, E-mail: dejesusmb@gmail.com; Radaic, Allan [University of Campinas-UNICAMP, Department of Biochemistry, Institute of Biology (Brazil); Zuhorn, Inge S. [University of Groningen, Department of Membrane Cell Biology, University Medical Center (Netherlands); Paula, Eneida de [University of Campinas-UNICAMP, Department of Biochemistry, Institute of Biology (Brazil)

    2013-10-15

    Solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) have been intensively investigated for different applications, including their use as drug and gene delivery systems. Different techniques have been employed to produce lipid nanoparticles, of which high pressure homogenization is the standard technique that is adopted nowadays. Although this method has a high efficiency, does not require the use of organic solvents, and allows large-scale production, some limitations impede its application at laboratory scale: the equipment is expensive, there is a need of huge amounts of surfactants and co-surfactants during the preparation, and the operating conditions are energy intensive. Here, we present the microemulsion extrusion technique as an alternative method to prepare lipid nanoparticles. The parameters to produce lipid nanoparticles using microemulsion extrusion were established, and the lipid particles produced (SLN, NLC, and liposomes) were characterized with regard to size (from 130 to 190 nm), zeta potential, and drug (mitoxantrone) and gene (pDNA) delivery properties. In addition, the particles' in vitro co-delivery capacity (to carry mitoxantrone plus pDNA encoding the phosphatase and tensin homologue, PTEN) was tested in normal (BALB 3T3 fibroblast) and cancer (PC3 prostate and MCF-7 breast) cell lines. The results show that the microemulsion extrusion technique is fast, inexpensive, reproducible, free of organic solvents, and suitable for small volume preparations of lipid nanoparticles. Its application is particularly interesting when using rare and/or costly drugs or ingredients (e.g., cationic lipids for gene delivery or labeled lipids for nanoparticle tracking/diagnosis)

  12. Microemulsion extrusion technique: a new method to produce lipid nanoparticles

    International Nuclear Information System (INIS)

    Jesus, Marcelo Bispo de; Radaic, Allan; Zuhorn, Inge S.; Paula, Eneida de

    2013-01-01

    Solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) have been intensively investigated for different applications, including their use as drug and gene delivery systems. Different techniques have been employed to produce lipid nanoparticles, of which high pressure homogenization is the standard technique that is adopted nowadays. Although this method has a high efficiency, does not require the use of organic solvents, and allows large-scale production, some limitations impede its application at laboratory scale: the equipment is expensive, there is a need of huge amounts of surfactants and co-surfactants during the preparation, and the operating conditions are energy intensive. Here, we present the microemulsion extrusion technique as an alternative method to prepare lipid nanoparticles. The parameters to produce lipid nanoparticles using microemulsion extrusion were established, and the lipid particles produced (SLN, NLC, and liposomes) were characterized with regard to size (from 130 to 190 nm), zeta potential, and drug (mitoxantrone) and gene (pDNA) delivery properties. In addition, the particles’ in vitro co-delivery capacity (to carry mitoxantrone plus pDNA encoding the phosphatase and tensin homologue, PTEN) was tested in normal (BALB 3T3 fibroblast) and cancer (PC3 prostate and MCF-7 breast) cell lines. The results show that the microemulsion extrusion technique is fast, inexpensive, reproducible, free of organic solvents, and suitable for small volume preparations of lipid nanoparticles. Its application is particularly interesting when using rare and/or costly drugs or ingredients (e.g., cationic lipids for gene delivery or labeled lipids for nanoparticle tracking/diagnosis)

  13. Room temperature ferromagnetism in ZnO prepared by microemulsion

    Directory of Open Access Journals (Sweden)

    Qingyu Xu

    2011-09-01

    Full Text Available Clear room temperature ferromagnetism has been observed in ZnO powders prepared by microemulsion. The O vacancy (VO clusters mediated by the VO with one electron (F center contributed to the ferromagnetism, while the isolated F centers contributed to the low temperature paramagnetism. Annealing in H2 incorporated interstitial H (Hi in ZnO, and removed the isolated F centers, leading to the suppression of the paramagnetism. The ferromagnetism has been considered to originate from the VO clusters mediated by the Hi, leading to the enhancement of the coercivity. The ferromagnetism disappeared after annealing in air due to the reduction of Hi.

  14. Design of microemulsion system suitable for the oral delivery of poorly aqueous soluble beta-carotene.

    Science.gov (United States)

    Peng, Cheng; Svirskis, Darren; Lee, Sung Je; Oey, Indrawati; Kwak, Hae-Soo; Chen, Guanyu; Bunt, Craig; Wen, Jingyuan

    2017-02-14

    Beta-carotene is a potent antioxidant for maintaining human health. However, its oral absorption is low due to poor aqueous solubility of less than 1 μg/ml. A microemulsion delivery system was designed to solubilize beta-carotene toward enhancing its oral bioavailability. From seven pseudoternary diagrams constructed, three systems were selected with large microemulsion areas suitable for oral administration and dilution in the predominately aqueous gastrointestinal fluids. Conductivity and rheology characterization were conducted along four dilution lines within the selected systems. Three pseudoternary-phase diagrams were selected with large microemulsion regions, >60% of the total phase diagram area, which provide microemulsions with higher drug-loading capacity. A phenomenon was observed by which both propylene glycol and Capmul MCM EP stabilize the microstructure of the microemulsions has been proposed based on the characterization studies. An optimal bicontinuous microemulsion formulation was selected comprising 12% orange oil, 24% Capmul MCM, 18% Tween 20, 6% Labrasol, 20% propylene glycol and 20% water, with a high beta-carotene loading capacity of 140.8 μg/ml and droplet size of 117.4 nm. In conclusion, the developed novel microemulsion formulation allows solubilizing beta-carotene and is a promising basis for further development as a functional beverage.

  15. Formulation and optimization of mucoadhesive microemulsion containing mirtazapine for intranasal delivery

    Directory of Open Access Journals (Sweden)

    Hetal P Thakkar

    2014-01-01

    Full Text Available Background: Mirtazapine, an antidepressant drug, has absolute bioavailability of only 50% due to high first pass metabolism. Aim: The purpose of this study was to develop and optimize mucoadhesive microemulsion containing mirtazapine for intranasal delivery. Materials and Methods: Based on solubility study, Capmul Medium chain Monoglyceride, Tween 80 and polyethylene glycol (PEG 400 were selected as oil, surfactant and co surfactant respectively. Microemulsions were prepared using water titration method. 3:1% w/w ratio (Tween 80: PEG 400 was selected for formulation development. The prepared microemulsions were optimized for globule size, zeta potential, % transmittance and polydispersity index. The optimized batch was further characterized for % drug content, conductivity and transmission electron microscopy. Results and Conclusion: All the parameters showed the suitability of microemulsion of mirtazapine for intranasal delivery. Chitosan (0.5% w/w was used as a polymer for the preparation of mucoadhesive microemulsion to enhance the retention time in the nasal mucosa. Results of nasal toxicity study using excised sheep nasal mucosa showed comparatively no damage to epithelium and so formulation was considered safe for nasal administration. mirtazapine mucoadhesive microemulsion showed the highest percentage of diffusion (57.11 ± 0.710% after 210 min during in-vitro drug diffusion study through sheep nasal mucosa, followed by mirtazapine microemulsion (46.08 ± 0.674% and finally by mirtazapine solution (17.63 ± 0.612%.

  16. Microemulsion-Based Topical Hydrogels of Tenoxicam for Treatment of Arthritis.

    Science.gov (United States)

    Goindi, Shishu; Narula, Manleen; Kalra, Atin

    2016-06-01

    Tenoxicam (TNX) is a non-steroidal anti-inflammatory drug (NSAID) used for the treatment of rheumatoid arthritis, osteoarthritis, ankylosing spondylitis, backache and pain. However, prolonged oral use of this drug is associated with gastrointestinal adverse events like peptic ulceration, thus necessitating its development as topical formulation that could obviate the adverse effects and improve patient compliance. The present study was aimed at development of microemulsion-based formulations of TNX for topical delivery at the affected site. The pseudoternary phase diagrams were developed and microemulsion formulations were prepared using Captex 300/oleic acid as oil, Tween 80 as surfactant and n-butanol/ethanol as co-surfactant. Optimized microemulsions were characterized for drug content, droplet size, viscosity, pH and zeta potential. The ex vivo permeation studies through Laca mice skin were performed using Franz diffusion cell assembly, and the permeation profile of the microemulsion formulation was compared with aqueous suspension of drug and drug incorporated in conventional cream. Microemulsion formulations of TNX showed significantly higher (p Microemulsion formulations were found to be superior in controlling inflammation as compared to conventional topical dosage forms and showed efficacy equivalent to oral formulation. Results suggest that the developed microemulsion formulations may be used for effective topical delivery of TNX to treat various inflammatory conditions.

  17. Formulation, physicochemical characterization and stability study of lithium-loaded microemulsion system.

    Science.gov (United States)

    Mouri, Abdelkader; Legrand, Philippe; El Ghzaoui, Abdeslam; Dorandeu, Christophe; Maurel, Jean Claude; Devoisselle, Jean-Marie

    2016-04-11

    Lithium biocompatible microemulsion based on Peceol(®), lecithin, ethanol and water was studied in attempt to identify the optimal compositions in term of drug content, physicochemical properties and stability. Lithium solubilization in microemulsion was found to be compatible with a drug-surfactant binding model. Lithium ions were predominantly solubilized within lecithin head group altering significantly the interfacial properties of the system. Pseudo-ternary phase diagrams of drug free and drug loaded microemulsions were built at constant ethanol/lecithin weight ratio (40/60). Lithium loaded microemulsion has totally disappeared in the Peceol(®) rich part of phase diagram; critical fractions of lecithin and ethanol were required for the formation of stable microemulsion. The effect of lithium concentration on the properties and physical stability of microemulsions were studied using microscopy, Karl Fischer titrations, rheology analyses, conductivity measurements and centrifugation tests. The investigated microemulsions were found to be stable under accelerated storage conditions. The systems exhibited low viscosity and behaved as Newtonian fluid and no structural transition was shown. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Microemulsion of babassu oil as a natural product to improve human immune system function.

    Science.gov (United States)

    Pessoa, Rafael Souza; França, Eduardo Luzia; Ribeiro, Elton Brito; Lanes, Patrícia Kelly Dias; Chaud, Natalina Galdeano Abud; Moraes, Lucélia Campelo Albuquerque; Honorio-França, Adenilda Cristina

    2015-01-01

    The aim of this study was to develop and characterize a babassu oil microemulsion system and determine the effect of this microemulsion on the functional activity of phagocytes. The microemulsion was formulated using distilled water, babassu as the oil phase component, Sorbitan monooleate-Span 80(®) (SP), Polysorbate 80-Tween 80(®) (TW), and 1-butanol (BT). Pseudoternary diagrams were prepared, and microemulsion diagram regions were preselected. Rheological characterization and preliminary and accelerated stability tests were performed. The effect of the microemulsion on the interactions between leukocytes and bacteria was determined by superoxide release, phagocytosis, and microbicidal activity. The developed formulation SP/TW/BT (4.2/4.8/1.0) was classified as oil/water, showed a Newtonian profile, and had linear viscosity. When we assessed the interaction of the microemulsion or babassu oil with phagocytes, we observed an increase in superoxide, phagocytosis, and microbicidal activity. The babassu oil microemulsion system is an option for future applications, including for vaccine delivery systems. Babassu oil is a natural product, so is an alternative for future immunotherapy strategies, in particular for infectious diseases.

  19. Development of w/o microemulsion for transdermal delivery of iodide ions.

    Science.gov (United States)

    Lou, Hao; Qiu, Ni; Crill, Catherine; Helms, Richard; Almoazen, Hassan

    2013-03-01

    The objective of this study was to develop a water-in-oil (w/o) microemulsion which can be utilized as a transdermal delivery for iodide ions. Several w/o microemulsion formulations were prepared utilizing Span 20, ethanol, Capryol 90®, and water. The selected formulations had 5%, 10%, 15%, 20%, and a maximum of 23% w/w water content. Potassium iodide (KI) was incorporated in all formulations at 5% w/v. Physicochemical characterizations were conducted to evaluate the structure and stability. These studies included: mean droplet size, pH, viscosity, conductivity, and chemical stability tests. In vitro human skin permeation studies were conducted to evaluate the diffusion of the iodide ion through human skin. The w/o microemulsion formulations were stable and compatible with iodide ions with water content ranging from 5% to 23% w/w. The addition of KI influenced the physicochemical properties of microemulsion as compared to blank microemulsion formulations. In vitro human skin permeation studies indicated that selected formulations improved iodide ion diffusion significantly as compared to control (KI solution; P valuemicroemulsion. Span 20, ethanol and Capryol 90 protected the iodide ions against oxidation and formed a stable microemulsion. It is worth to note that according to Hofmeister series, iodide ions tend to lower the interfacial tension between water and oil and consequently enhance overall stability. This work illustrates that microemulsion system can be utilized as a vehicle for the transdermal administration of iodide.

  20. Microemulsion-loaded hydrogel formulation of butenafine hydrochloride for improved topical delivery.

    Science.gov (United States)

    Pillai, Anilkumar B; Nair, Jyothilaksmi V; Gupta, Nishant Kumar; Gupta, Swati

    2015-09-01

    Topical microemulsion systems for the antifungal drug, butenafine hydrochloride (BTF) were designed and developed to overcome the problems associated with the cutaneous delivery due to poor water solubility. The solubility of BTF in oils, surfactants and co-surfactants was evaluated to screen the components of the microemulsion. Isopropyl palmitate was used as the oil phase, aerosol OT as the surfactant and sorbitan monooleate as co-surfactant. The pseudoternary diagrams were constructed to identify the area of microemulsion existence and optimum systems were designed. The systems were assessed for drug-loading efficiency and characterized for pH, robustness to dilution, globule size, drug content and stability. Viscosity analysis, spreadability, drug content assay, ex vivo skin permeation study and antifungal activity assay were performed for the optimized microemulsion-loaded hydrogel. The optimized BTF microemulsion had a small and uniform globule size. The incorporation of microemulsion system into Carbopol 940 gel was found to be better as compared to sodium alginate or hydroxyl propyl methyl cellulose (HPMC K4 M) gel. The developed gel has shown better ex vivo skin permeation and antifungal activity when compared to marketed BTF cream. Thus, the results provide a basis for the successful delivery of BTF from microemulsion-loaded hydrogel formulation, which resulted in improved penetration of drug and antifungal activity in comparison with commercial formulation of BTF.

  1. Formation of nanoparticles on reverse micelles: SANS studies

    International Nuclear Information System (INIS)

    Sim, Jae-Hyun; Park, Jaejung; Kim, Myungwoong; Hwan Bang, Jeong; Park, Sangwook; Sohn, Daewon

    2006-01-01

    The structure of polymethyl methacrylate (PMMA) on the surface of reverse micelles was investigated by small-angle neutron scattering (SANS). The water-in-oil microemulsion containing initiators in the inner part of reverse micelle was prepared with surfactant, poly(oxyethylene) nonylphenyl ether (NP5, H(CH 2 ) 9 Ph(OC 2 H 4 ) 5 OH), water, cyclohexane and adequate initiators, sodium metabisulfate (SDS) and potassium persulfate (KPS), for aimed polymerization (PMMA). Various model fittings such as the core-shell sphere model and hard sphere model containing smearing effect reveal that polymer shell thickness changes from 52 to 60 A, respectively, with increase of monomer concentration

  2. Stability and solubility improvement of Sompoi (Acacia concinna Linn. pod extract by topical microemulsion

    Directory of Open Access Journals (Sweden)

    Worrapan Poomanee

    2017-07-01

    Full Text Available The aim of this study was to enhance the solubility and stability of Acacia concinna extract by loading in a microemulsion for topical application. Both physical appearance and biological activities of the extract-loaded microemulsion were determined in comparison with the extract solution. Pseudoternary phase diagrams of three oil types including tea seed oil, grape seed oil, and sesame oil, together with polysorbate 85 or the mixture of polysorbate 85 and sorbitan oleate as surfactants, and absolute ethanol as a co-surfactant were constructed to optimize the microemulsion area. The selected microemulsion was then characterized for droplet size, polydispersity index, and viscosity. Tea seed oil exhibited the highest microemulsion area in the phase diagram because it had the highest unsaturated fatty acid content. The microemulsion composed of tea seed oil (5%, polysorbate 85 (40%, ethanol (20%, and water (35% exhibited Newtonian flow behavior with the droplet size and polydispersity index of 68.03 ± 1.09 nm and 0.44 ± 0.04, respectively. After 4% w/w of the extract was incorporated into the microemulsion, larger droplets size was observed (239.77 ± 12.69 nm with a lower polydispersity index (0.37 ± 0.02. After storage in various conditions, both physical appearances and the stability of biological activity of the extract-loaded microemulsion were improved compared to the solution. Therefore, the A. concinna loaded microemulsion may be a promising carrier for further development into a topical formulation and clinical trials for pharmaceutical and cosmeceutical applications are also suggested.

  3. Preparation of poly (alkylcyanoacrylate) nanoparticles by polymerization of water-free microemulsions

    DEFF Research Database (Denmark)

    Krauel, Karen; Graf, Anja; Hook, Sarah M

    2006-01-01

    designated as droplet, bicontinuous or solution type microemulsions using conductivity, viscosity and self-diffusion NMR. Nanoparticles were prepared by polymerization of selected microemulsions with ethyl-2-cyanoacrylate and the morphology of the particles was investigated. Addition of monomer to all types...... that polymerization is expected to occur at a water-oil interface by base-catalysed polymerization. It would appear that propylene glycol is sufficiently nucleophilic to initiate the polymerization. The use of water-free microemulsions as templates for the preparation of poly (alkylcyanoacrylate) nanoparticles opens...

  4. Tacrolimus loaded biocompatible lecithin-based microemulsions with improved skin penetration: Structure characterization and in vitro/in vivo performances.

    Science.gov (United States)

    Savić, Vedrana; Todosijević, Marija; Ilić, Tanja; Lukić, Milica; Mitsou, Evgenia; Papadimitriou, Vassiliki; Avramiotis, Spyridon; Marković, Bojan; Cekić, Nebojša; Savić, Snežana

    2017-08-30

    In order to improve skin penetration of tacrolimus we aimed to develop potentially non-irritant, lecithin-based microemulsions containing ethanol, isopropanol and/or propylene glycol as cosurfactants, varying caprylic/capric triglycerides and propylene glycol monocaprylate as oil phase. The influence of excipients on the size of microemulsion region in pseudo-ternary phase diagrams and their ability to form different types of microemulsions was evaluated. The comprehensive physicochemical characterization of microemulsions and the evaluation of their structure was performed, while the localization of tacrolimus in microemulsions was further investigated using electron paramagnetic resonance spectroscopy. Moreover, stability studies proved no change in tacrolimus content during one year of storage at room temperature. In addition, in vivo skin performance indicated no skin irritation potential of blank microemulsions, whereas in vitro release testing using Franz diffusion cells showed superior release rate of tacrolimus from microemulsions (0.98±0.10 and 0.92±0.11μg/cm 2 /h for two bicontinuous and 1.00±0.24μg/cm 2 /h for oil-in-water microemulsion) compared to referent Protopic ointment (0.15±0.08μg/cm 2 /h). Furthermore, ex vivo penetration assessed through porcine ear skin using tape stripping, confirmed superiority of two microemulsions related to the reference, implying developed microemulsions as promising carriers for dermal delivery of tacrolimus. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Organic, cross-linking, and shape-stabilized solar thermal energy storage materials: A reversible phase transition driven by broadband visible light

    International Nuclear Information System (INIS)

    Wang, Yunming; Tang, Bingtao; Zhang, Shufen

    2014-01-01

    Graphical abstract: Organic shape-stabilized solar thermal energy storage materials (OCSPCMs) with broadband harvesting for visible light were obtained by crosslinking and color matching, which provided a new platform for improving the efficiency of solar radiation utilization. - Highlights: • Novel phase change materials (OCSPCMs) were obtained by crosslinking and color matching. • The η of the OCSPCM was higher than 0.74 (visible light from 400 nm to 700 nm). • The phase change latent heats of the OCSPCMs were more than 120 J/g. • The OCSPCM has excellent form-stable effect during phase change process. - Abstract: Broadband visible sunlight usage and shape-stabilized effect were achieved using organic, cross-linking, and shape-stabilized phase-changed materials (OCSPCMs) with broadband visible light absorption, which were obtained by cross-linking reticulation and color matching (yellow, red, and blue) according to solar irradiation energy density. The obtained OCSPCMs exhibited excellent form-stable phase-change energy storage and broadband visible light-harvesting. Under broadband irradiation (from 400 nm to 700 nm), the light-to-heat conversion and the thermal energy storage efficiency (η > 0.74) of the OCSPCMs were significantly improved upon solar irradiation by color matching compared with those of OCSPCMs with single-band selective absorption of visible light (yellow, red, or blue). Differential scanning calorimetric results indicated that the phase change temperatures and latent heats of OCSPCMs ranged from 32.6 °C to 60.2 °C and from 120.1 J/g to 132.7 J/g, respectively. The novel materials show a reversible (more than 200 cycles) phase transition via ON/OFF switching of visible light irradiation

  6. Reversible p-type conductivity in H passivated nitrogen and phosphorous codoped ZnO thin films using rapid thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Mannam, Ramanjaneyulu, E-mail: ramu.nov9@gmail.com [Department of Physics, Nano Functional Materials Technology Centre and Materials Science Research Centre, Indian Institute of Technology Madras, Chennai 600036 (India); Kumar, E. Senthil [SRM Research Institute, Department of Physics and Nanotechnology, SRM University, Kattankulathur 603203, Tamil Nadu (India); DasGupta, Nandita [Microelectronics and MEMS Laboratory, Electrical Engineering Department, Indian Institute of Technology Madras, Chennai 600036 (India); Ramachandra Rao, M.S., E-mail: msrrao@iitm.ac.in [Department of Physics, Nano Functional Materials Technology Centre and Materials Science Research Centre, Indian Institute of Technology Madras, Chennai 600036 (India)

    2017-04-01

    Highlights: • Electrical transport measurements revel that the (P, N) codoped ZnO thin films exhibited change in conductivity from p-type to n-type over a span of 120 days. • Hydrogen and carbon are found to be the main unintentional impurities in n-type (P, N) codoped ZnO thin films. • Rapid thermal annealing has been used to remove both H and C from the films. • Carbon can be removed at an annealing temperature of 600 °C, whereas, the dissociation of N−H complex takes place only at 800 °C. • The n-type (P, N) codoped ZnO thin film exhibited change in conductivity to p-type at an annealing temperature of 800 °C. - Abstract: We demonstrate reversible p-type nature of pulsed laser deposited (P, N) codoped ZnO thin films using rapid thermal annealing process. As grown thin films exhibited change in conductivity from p to n-type over a span of 120 days. Non-annealed n-type thin films contain unintentional donor impurities such as hydrogen and carbon. X-ray photoelectron spectroscopy and Raman measurements conclusively show that hydrogen passivates nitrogen acceptors by forming N−H complex. Carbon can be annealed out at 600 °C, whereas, the dissociation of N−H complex takes place at 800 °C. The films revert its p-type nature at an annealing temperature of 800 °C.

  7. Antifungal activity of topical microemulsion containing a thiophene derivative

    Directory of Open Access Journals (Sweden)

    Geovani Pereira Guimarães

    2014-06-01

    Full Text Available Fungal infections have become a major problem of worldwide concern. Yeasts belonging to the Candida genus and the pathogenic fungus Cryptococcus neoformans are responsible for different clinical manifestations, especially in immunocompromised patients. Antifungal therapies are currently based on a few chemotherapeutic agents that have problems related to effectiveness and resistance profiles. Microemulsions are isotropic, thermodynamically stable transparent systems of oil, water and surfactant that can improve the solubilization of lipophilic drugs. Taking into account the need for more effective and less toxic drugs along with the potential of thiophene derivatives as inhibitors of pathogenic fungi growth, this study aimed to evaluate the antifungal activity of a thiophene derivative (5CN05 embedded in a microemulsion (ME. The minimum inhibitory concentration (MIC was determined using the microdilution method using amphotericin B as a control. The formulations tested (ME- blank and ME-5CN05 showed physico-chemical properties that would allow their use by the topical route. 5CN05 as such exhibited moderate or weak antifungal activity against Candida species (MIC = 270-540 µg.mL-1 and good activity against C. neoformans (MIC = 17 µg.mL-1. Candida species were susceptible to ME-5CN05 (70-140 µg.mL-1, but C. neoformans was much more, presenting a MIC value of 2.2 µg.mL-1. The results of this work proved promising for the pharmaceutical industry, because they suggest an alternative therapy against C. neoformans.

  8. Phenobarbital loaded microemulsion: development, kinetic release and quality control

    Directory of Open Access Journals (Sweden)

    Kayo Alves Figueiredo

    Full Text Available ABSTRACT This study aimed to obtain and characterize a microemulsion (ME containing phenobarbital (PB. The PB was incorporated in the proportion of 5% and 10% in a microemulsion system containing Labrasol(r, ethanol, isopropyl myristate and purified water. The physicochemical characterization was performed and the primary stability of the ME was evaluated. An analytical method was developed using spectrophotometry in UV = 242 nm. The kinetics of the in vitro release (Franz model of the ME and the emulsion (EM containing PB was evaluated. The incorporation of PB into ME at concentrations of 5 and 10% did not change pH and resistance to centrifugation. There was an increase in particle size, a decrease of conductivity and a change in the refractive index in relation to placebo ME. The ME remained stable in preliminary stability tests. The analytical method proved to be specific, linear, precise, accurate and robust. Regarding the kinetics of the in vitro release, ME obtained an in vitro release profile greater than the EM containing PB. Thus, the obtained ME has a potential for future transdermal application, being able to compose a drug delivery system for the treatment of epilepsy.

  9. In situ microemulsion synthesis of hydroxyapatite-MgFe{sub 2}O{sub 4} nanocomposite as a magnetic drug delivery system

    Energy Technology Data Exchange (ETDEWEB)

    Foroughi, Firoozeh [Young Researchers and Elite Club, Najafabad Branch, Islamic Azad University, Najafabad (Iran, Islamic Republic of); Hassanzadeh-Tabrizi, S.A., E-mail: tabrizi1980@gmail.com [Young Researchers and Elite Club, Najafabad Branch, Islamic Azad University, Najafabad (Iran, Islamic Republic of); Bigham, Ashkan [Advanced Materials Research Center, Department of Materials Engineering, Najafabad Branch, Islamic Azad University, Najafabad (Iran, Islamic Republic of)

    2016-11-01

    In this study, an innovative synthesis process has been developed to produce hydroxyapatite-magnesium ferrite (HA-MgFe{sub 2}O{sub 4}) nanocomposite. In addition, the effect of calcination temperature on drug delivery behavior of produced samples was investigated. HA-MgFe{sub 2}O{sub 4} nanocomposite was prepared via one-step modified reverse microemulsion synthesis route. The resulting products were characterized by X-ray Diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), and Brunauer–Emmett–Teller surface area analysis (BET). The calcined samples at 500 and 700 °C demonstrated mesoporous characteristics and large specific surface areas of 88 and 32 m{sup 2}/g, respectively. TEM and VSM results showed that the nanocomposite calcined at 700 °C has core–shell morphology and a maximum saturation magnetization of 9.47 emu g{sup −1}. - Highlights: • A one-step modified reverse microemulsion method has been used to produce hydroxyapatite-magnesium ferrite. • Nanocomposites were loaded with ibuprofen as a magnetic drug delivery system. • The drug release behavior of nanocomposites were studied at different calcination temperature.

  10. Testing of resveratrol microemulsion photostability and protective effect against UV induced oxidative stress.

    Science.gov (United States)

    Juškaitė, Vaida; Ramanauskienė, Kristina; Briedis, Vitalis

    2017-06-27

    Resveratrol is well known for its antioxidant activity and susceptibility to ultraviolet radiation. Development of formulations providing improved stability and relevant drug delivery of resveratrol is still a challenging task. The aim of this study was to determine protective characteristics of formulated microemulsions by evaluating photoisomerization of resveratrol and to investigate the effects of resveratrol on human keratinocyte cells under oxidative stress caused by ultraviolet radiation. Incorporation of resveratrol into microemulsions resulted in increased photostability of active compounds and the results demonstrated that photodegradation of resveratrol was significantly delayed. Results of biopharmaceutical evaluation in vitro demonstrated that up to 60 % of resveratrol was released from microemulsions within 6 hours under a constant release rate profile. In vivo biological testing confirmed the ability of resveratrol to protect cells from oxidative stress and to increase cell viability. It was concluded that microemulsions might be considered in the development of UV light sensitive compounds.

  11. Testing of resveratrol microemulsion photostability and protective effect against UV induced oxidative stress

    Directory of Open Access Journals (Sweden)

    Juškaitė Vaida

    2017-06-01

    Full Text Available Resveratrol is well known for its antioxidant activity and susceptibility to ultraviolet radiation. Development of formulations providing improved stability and relevant drug delivery of resveratrol is still a challenging task. The aim of this study was to determine protective characteristics of formulated microemulsions by evaluating photoisomerization of resveratrol and to investigate the effects of resveratrol on human keratinocyte cells under oxidative stress caused by ultraviolet radiation. Incorporation of resveratrol into microemulsions resulted in increased photostability of active compounds and the results demonstrated that photodegradation of resveratrol was significantly delayed. Results of biopharmaceutical evaluation in vitro demonstrated that up to 60 % of resveratrol was released from microemulsions within 6 hours under a constant release rate profile. In vivo biological testing confirmed the ability of resveratrol to protect cells from oxidative stress and to increase cell viability. It was concluded that microemulsions might be considered in the development of UV light sensitive compounds.

  12. Reverse Algols

    Science.gov (United States)

    Leung, K. C.

    1989-01-01

    Reverse Algols, binary systems with a semidetached configuration in which the more massive component is in contact with the critical equipotential surface, are examined. Observational evidence for reverse Algols is presented and the parameters of seven reverse Algols are listed. The evolution of Algols and reverse Algols is discussed. It is suggested that, because reverse Algols represent the premass-reversal semidetached phase of close binary evolution, the evolutionary time scale between regular and reverse Algols is the ratio of the number of confirmed systems of these two Algol types.

  13. On small-angle neutron scattering from microemulsion droplets: the role of shape fluctuations

    International Nuclear Information System (INIS)

    Lisy, V.; Brutovsky, B.

    2001-01-01

    The form factor and intensity of static neutron scattering from microemulsion droplets are calculated. The droplet is modeled by a double-layered sphere consisting of a fluid core and a thin surfactant layer, immersed in another fluid. All the three components are incompressible and characterized by different scattering length densities. As distinct from previous descriptions of small-angle neutron scattering (SANS), we consistently take into account thermal fluctuations of the droplet shape, to the second order of the fluctuations of the droplet radius. The properties of the layer are described within Helfrich's concept of the elasticity of curved interfaces. It is shown that in many cases the account for the fluctuations is essential for the interpretation of SANS. Information about two elastic constants k and k bar (so far extracted from the experiments in the combination 2k + k bar) can be now simultaneously obtained from SANS for the system in conditions of two-phase coexistence. As an illustration, the theory is applied for the quantitative description of SANS experiments from the literature

  14. Influence of the solubilization of ribonuclease and of its hydrophobic derivatives on water-in-oil microemulsions

    International Nuclear Information System (INIS)

    Michel, Fabienne

    1993-01-01

    This research thesis addresses the study of the structural disruption of a water-in-oil microemulsion during the solubilization of an enzyme. More precisely, the microemulsion is the water/isooctane system, stabilised by the commonly named AOT anionic surfactant, and the disrupting agent is an enzymatic protein, ribonuclease A. The author addresses the following topics: interactions in microemulsion, percolation in microemulsion, use of microemulsions as micro-reactor, chemical modification of enzymes, and reactivity of enzymes. After a recall of the main results concerning AOT inverse micelles, the author addresses the influence of ribonuclease solubilisation on the micellar system. The micellar environment is then used as a micro-reactor in order to fix hydrophobic molecules in a covalent way onto the ribonuclease A, and then to promote the percolation process. The author then studies the structure of the microemulsion in presence of modified enzymes [fr

  15. Nanostructured lipid carriers versus microemulsions for delivery of the poorly water-soluble drug luteolin.

    Science.gov (United States)

    Liu, Ying; Wang, Lan; Zhao, Yiqing; He, Man; Zhang, Xin; Niu, Mengmeng; Feng, Nianping

    2014-12-10

    Nanostructured lipid carriers and microemulsions effectively deliver poorly water-soluble drugs. However, few studies have investigated their ability and difference in improving drug bioavailability, especially the factors contributed to the difference. Thus, this study was aimed at investigating their efficiency in bioavailability enhancement based on studying two key processes that occur in NLC and ME during traverse along the intestinal tract: the solubilization process and the intestinal permeability process. The nanostructured lipid carriers and microemulsions had the same composition except that the former were prepared with solid lipids and the latter with liquid lipids; both were evaluated for particle size and zeta potential. Transmission electron microscopy, differential scanning calorimetry, and X-ray diffraction were performed to characterize their properties. Furthermore, in vitro drug release, in situ intestinal absorption, and in vitro lipolysis were studied. The bioavailability of luteolin delivered using nanostructured lipid carriers in rats was compared with that delivered using microemulsions and suspensions. The in vitro analysis revealed different release mechanisms for luteolin in nanostructured lipid carriers and microemulsions, although the in situ intestinal absorption was similar. The in vitro lipolysis data indicated that digestion speed and extent were higher for microemulsions than for nanostructured lipid carriers, and that more of the former partitioned to the aqueous phase. The in vivo bioavailability analysis in rats indicated that the oral absorption and bioavailability of luteolin delivered using nanostructured lipid carriers and microemulsions were higher than those of luteolin suspensions. Nanostructured lipid carriers and microemulsions improved luteolin's oral bioavailability in rats. The rapid lipid digestion and much more drug solubilized available for absorption in microemulsions may contribute to better absorption and

  16. Microemulsion of babassu oil as a natural product to improve human immune system function

    Directory of Open Access Journals (Sweden)

    Pessoa RS

    2014-12-01

    Full Text Available Rafael Souza Pessoa,1 Eduardo Luzia França,1,2­ Elton Brito Ribeiro,1 Patrícia Kelly Dias Lanes,1 Natalina Galdeano Abud Chaud,1 Lucélia Campelo Albuquerque Moraes,2 Adenilda Cristina Honorio-França1,2 1Post Graduate Program in Material Science, 2Institute of Biological and Health Science, Federal University of Mato Grosso, Barra do Garças, MT, Brazil Background: The aim of this study was to develop and characterize a babassu oil microemulsion system and determine the effect of this microemulsion on the functional activity of phagocytes.Methods: The microemulsion was formulated using distilled water, babassu as the oil phase component, Sorbitan monooleate-Span 80® (SP, Polysorbate 80-Tween 80® (TW, and 1-butanol (BT. Pseudoternary diagrams were prepared, and microemulsion diagram regions were preselected. Rheological characterization and preliminary and accelerated stability tests were performed. The effect of the microemulsion on the interactions between leukocytes and bacteria was determined by superoxide release, phagocytosis, and microbicidal activity.Results: The developed formulation SP/TW/BT (4.2/4.8/1.0 was classified as oil/water, showed a Newtonian profile, and had linear viscosity. When we assessed the interaction of the microemulsion or babassu oil with phagocytes, we observed an increase in superoxide, phagocytosis, and microbicidal activity.Conclusion: The babassu oil microemulsion system is an option for future applications, including for vaccine delivery systems. Babassu oil is a natural product, so is an alternative for future immunotherapy strategies, in particular for infectious diseases. Keywords: vegetable oil, babassu, microemulsion, phagocytes, delivery systems

  17. Sustained release of nucleic acids from polymeric nanoparticles using microemulsion precipitation in supercritical carbon dioxide.

    Science.gov (United States)

    Ge, Jun; Jacobson, Gunilla B; Lobovkina, Tatsiana; Holmberg, Krister; Zare, Richard N

    2010-12-21

    A general approach for producing biodegradable nanoparticles for sustained nucleic acid release is presented. The nanoparticles are produced by precipitating a water-in-oil microemulsion in supercritical CO(2). The microemulsion consists of a transfer RNA aqueous solution (water phase), dichloromethane containing poly(l-lactic acid)-poly(ethylene glycol) (oil phase), the surfactant n-octyl β-D-glucopyranoside, and the cosurfactant n-butanol.

  18. Antimicrobial effects of a microemulsion and a nanoemulsion on enteric and other pathogens and biofilms

    OpenAIRE

    Teixeira, Paula C.; Leite, Gonçalo M.; Domingues, Ricardo J.; Silva, Joana; Gibbs, Paul A.; Ferreira, João Paulo

    2007-01-01

    Some microemulsions and nanoemulsions may have antimicrobial properties and be effective anti-biofilm agents. We examined the abilities of two fine emulsions, designated BCTP and TEOP, to inactivate suspensions of vegetative cells of Salmonella spp. Escherichia coli 0157:H7 (VT-), Pseudomonas aeruginosa, Staphylococcus aureus and Listeria monocytogenes. BCTP is an O/W nanoemulsion of soybean oil and tri-n-butyl phosphate emulsified with Triton X-100, while TEOP is an O/W microemulsion of ethy...

  19. Reverse Logistics

    OpenAIRE

    Kulikova, Olga

    2016-01-01

    This thesis was focused on the analysis of the concept of reverse logistics and actual reverse processes which are implemented in mining industry and finding solutions for the optimization of reverse logistics in this sphere. The objective of this paper was the assessment of the development of reverse logistics in mining industry on the example of potash production. The theoretical part was based on reverse logistics and mining waste related literature and provided foundations for further...

  20. Solubility limit of methyl red and methylene blue in microemulsions and liquid crystals of water, sds and pentanol systems

    OpenAIRE

    Beri, D.; Pratami, A.; Gobah, P. L.; Dwimala, P.; Amran, A.

    2017-01-01

    Solubility of dyes in amphiphilic association structures of water, SDS and penthanol system (i.e. in the phases of microemulsions and liquid crystals) was attracted much interest due to its wide industrial and technological applications. This research was focused on understanding the solubility limitation of methyl red and methylene blue in microemulsion and liquid crystal phases. Experimental results showed that the highest solubility of methyl red was in LLC, followed by w/o microemulsion a...

  1. Water/oil type microemulsion systems containing lidocaine hydrochloride: in vitro and in vivo evaluation.

    Science.gov (United States)

    Dogrul, Ahmet; Arslan, Seyda Akkus; Tirnaksiz, Figen

    2014-01-01

    The purpose of this study was to develop a water/oil microemulsion containing lidocaine hydrochloride (4%) and to compare its local anaesthetic efficacy with commercial products. A pseudoternary diagram (Km:1/1 or 1/2) was constructed using lecithin/ethanol/oil/water. The droplet size, viscosity and release of the microemulsions were evaluated. Tail flick tests were conducted for in vivo effectiveness; the initiation time of effect, maximum effect, time to reach maximum effect, and relative efficacy were evaluated. The drug caused a significant increase in droplet size. The use of olive oil resulted in a decrease in the solubilisation parameter, as well as a reduction in the release. The droplet size and viscosity of the microemulsion composed of Miglyol/lecithin/ethanol/water/drug (Km:1/2) was lower than other microemulsions (8.38 nm, 6.9 mPa), and its release rate (1.61 mg/h) was higher. This system had a faster and more efficient anaesthetic effect than the other microemulsions and commercial products. Results indicate that a water/oil type microemulsion (Miglyol/lecithin/ethanol/water) has promising potential to increase the local anaesthetic effect.

  2. Enhanced Solubility and Permeability of Salicis cortex Extract by Formulating as a Microemulsion.

    Science.gov (United States)

    Piazzini, Vieri; Bigagli, Elisabetta; Luceri, Cristina; Bilia, Anna Rita; Bergonzi, Maria Camilla

    2018-04-24

    A microemulsion system was developed and investigated as a novel oral formulation to increase the solubility and absorption of Salicis cortex extract. This extract possesses many pharmacological activities, in particular, it is beneficial for back pain and osteoarthritic and rheumatic complaints. In this work, after qualitative and quantitative characterization of the extract and the validation of an HPLC/diode array detector analytical method, solubility studies were performed to choose the best components for microemulsion formulation. The optimized microemulsion consisted of 2.5 g of triacetin, as the oil phase, 2.5 g of Tween 20 as the surfactant, 2.5 g of labrasol as the cosurfactant, and 5 g of water. The microemulsion was visually checked, characterized by light scattering techniques and morphological observations. The developed formulation appeared transparent, the droplet size was around 40 nm, and the ζ -potential result was negative. The maximum loading content of Salicis cortex extract resulted in 40 mg/mL. Furthermore, storage stability studies and an in vitro digestion assay were performed. The advantages offered by microemulsion were evaluated in vitro using artificial membranes and cells, i.e., parallel artificial membrane permeability assay and a Caco-2 model. Both studies proved that the microemulsion was successful in enhancing the permeation of extract compounds, so it could be useful to ameliorate the bioefficacy of Salicis cortex. Georg Thieme Verlag KG Stuttgart · New York.

  3. Microemulsion formulation design and evaluation for hydrophobic compound: Catechin topical application.

    Science.gov (United States)

    Lin, Yu-Hsiang; Tsai, Ming-Jun; Fang, Yi-Ping; Fu, Yaw-Syan; Huang, Yaw-Bin; Wu, Pao-Chu

    2018-01-01

    The aim of the present study was to design a microemulsion for catechin topical application. A mixture experimental design with five independent variables (X 1 : oil, X 2 : surfactant, X 3 : catechin, X 4 : cosurfactant and X 5 : water) was developed, and the response surface methodology was used to study the effect of formulation components on physiochemical characteristics and penetration capacity of a catechin-loaded microemulsion, and to obtain an optimal microemulsion formulation. The results showed that the drug-loaded microemulsion formation and characteristics were related to many parameters of the components. The transdermal amounts in receiver cells and skin deposition amount remarkably increased about 4.1-111.6-fold and 0.6-7.6-fold respectively. The lag time was significantly shortened from 10h to 1.0-6.7h. The optimal formulation with 20% surfactant, 30% cosurfactant and 2.6% Catechin was subjected to stability and irritation tests. The results showed that the physicochemical characteristics and catechin level of the drug-loaded microemulsion did not show significant degradation after 3 months of storage at 25°C.The catechin-loaded microemulsion did not cause significant irritation compared to the water-treated group. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Synthesis of Polysiloxanes In Microemulsion Via ring opening of D4

    Directory of Open Access Journals (Sweden)

    Liu Jiesheng

    2016-07-01

    Full Text Available Polydimethylsiloxane (PDMS has been synthesized by ring-opening polymerization of octamethylcyclotetrasiloxane (D4 in microemulsion with acidic catalyst. The structure and properties of microemulsion were characterized by Transmission Electron Microscopy (TEM, Fourier Transform Infrared Spectroscopy (FT-IR, Photo Correlation Spectroscopy (PCS. The effect of the variation in pH value, amount of catalyst, emulsifier and monomer dropping rate on the properties of microemulsion were investigated and discussed. The results showed that the particle size of the latex becomes smaller, and the distribution size becomes wider with increasing the content of catalyst and emulsifier. When pH value changed, the reaction rate of ring-opening of D4 was faster with strong acid than that under the weak acid condition. The emulsification of 2 % OP-10 (Alkylphenol polyoxyethylene ether and 3.0% DBSA (Dodecyl benzenesulfonic acid reached to equilibrium in microemulsion. As the amount of OP-10 increases, the size of particles lowered and their corresponding  distribution widened. It is observed that emulsifier (OP-10 does not affect the transparency of the microemulsion in the case of the application of DBSA. As the monomer dropping time increased, the grain size diminished and the size distribution widened. PCS results showed that the smallest particle size was around 20nm. Taking into account of the stability of the microemulsions, the dropping time of the monomer was around 30 min.

  5. Water-in-Oil Microemulsions for Protein Delivery: Loading Optimization and Stability.

    Science.gov (United States)

    Perinelli, Diego R; Cespi, Marco; Pucciarelli, Stefania; Vincenzetti, Silvia; Casettari, Luca; Lam, Jenny K W; Logrippo, Serena; Canala, Elisa; Soliman, Mahmoud E; Bonacucina, Giulia; Palmieri, Giovanni F

    2017-01-01

    Microemulsions are attractive delivery systems for therapeutic proteins and peptides due to their ability to enhance bioavailability. Although different proteins and peptides have been successfully delivered through such ternary systems, no information can be found about protein loading and the formulation stability when such microemulsions are prepared with pharmaceuticallyapproved oils and surfactants. The aim of this work was to optimise a ternary system consisting of water/ ethyl oleate/Span® 80-Tween® 80 and to determine its protein loading capacity and stability, using bovine serum albumin (BSA) as a model of biomolecule. The optimization was carried out using a Central Composite Design and all the prepared formulations were characterised through dynamic light scattering, rheology, optical and polarized microscopy. Subsequently, the maximum loading capacity was determined and the stability of the final microemulsion with the highest content of protein was followed over six months. To investigate the structural features of the protein, BSA was recovered from the microemulsion and analysed through fluorescence spectroscopy. After incorporation of the protein in the microemulsion, a decrease of its aqueous solubility was observed. However, the formulation remained stable over six months and the native-like state of the recovered protein was demonstrated by fluorescence spectroscopy Conclusion: This study demonstrated the feasibility of preparing microemulsions with the highest content of protein and their long-term stability. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  6. The use of microemulsion and flushing solutions to remediate diesel-polluted oil

    Energy Technology Data Exchange (ETDEWEB)

    Dnatas, T.N.C.; Moura, M.C.P.A.; Dants Neto, A.A; Pinheiro, F.S.H.T.; Barros Neto, E.L. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Dept. de Engenharia Quimica], E-mail: carlenise@eq.ufrn.br

    2007-07-15

    The applicability of a surfactant derived from coconut oil (saponified coconut oil - SCO) to remove diesel oil from contaminated soil was investigated. This surfactant was applied in aqueous solutions and in a microemulsion precursory solution (surfactant/cosurfactant/water). Bench-scale tests were carried out using both column and batch setups with artificially contaminated soil. Parameters tested, that have influence in microemulsion formation, include: cosurfactant nature, cosurfactant/surfactant ratio (C/S), and presence or absence of an electrolyte in the aqueous phase (NaCl). Upon construction of pseudo ternary phase diagrams it was observed that increasing C/S ratio and presence of electrolyte cause a reduction in the microemulsion region. Five washing solutions were tested: distilled water, distilled water with 0.5 wt.% NaCl, surfactant solution (0.5 wt.% SCO - above critical micelle concentration - CMC), and a microemulsion precursory solution with and without NaCl in its aqueous phase. It was observed that the formation of diesel-in-oil microemulsion makes easy the removal of contaminants from the used soil. It was found that in batch experiments a 74% contaminant removal can be achieved and in column experiments up to 75% diesel oil could be removed, showing the potential applicability of this surfactant in microemulsion systems for cleaning up contaminated sandy soils. (author)

  7. [Structure and dynamics of microemulsions in bulk, at interfaces, and in confined geometries

    International Nuclear Information System (INIS)

    1993-01-01

    The authors have been constructing a special purpose small angle neutron scattering spectrometer (SAND) in collaboration with IPNS of Argonne National Laboratory and Texaco Research Laboratories in Beacon, New York. The spectrometer, having a moderate neutron flux, will be uniquely suited for detailed studies of complex fluids in their various phases. This spectrometer will be fully available to general users of the small angle scattering community after a year of testing and upon installation of the auxiliary equipment. The general research objective of the MIT group is to continue studies of the microstructural relationship to phase-behavior in three-component microemulsion systems. Specifically, they shall study the (1) variation of bulk structures when a microemulsion undergoes a non-wetting to wetting transition, (2) correlating interfacial reflectivity measurements of these wetting transitions to the SANS results, (3) use the contrast variation technique they recently developed for measuring the mean and Gaussian curvatures of the surfactant sheet to study the structural inversion of water-in-oil to oil-in-water microemulsions and the transition of disordered bicontinuous microemulsion to ordered lamellar phases, (4) investigation of the effects of spatial confinement on the phase behavior and structure of bicontinuous microemulsions, and finally (5) they shall continue the study of the recently discovered non-exponential relaxation of droplet density fluctuations near the critical and percolation points in water-in-oil droplet microemulsions

  8. [Study on extracting and separating curcuminoids from Curcuma longa rhizome using ultrasound strengthen by microemulsion].

    Science.gov (United States)

    Yue, Chun-Hua; Zheng, Li-Tao; Guo, Qi-Ming; Li, Kun-Ping

    2014-05-01

    To establish a new method for the extraction and separation of curcuminoids from Curcuma longa rhizome by cloud-point preconcentration using microemulsions as solvent. The spectrophotometry was used to detect the solubility of curcumin in different oil phase, emulsifier and auxiliary emulsifier, and the microemulsion prescription was used for false three-phase figure optimization. The extraction process was optimized by uniform experiment design. The curcuminoids were separated from microemulsion extract by cloud-point preconcentration. Oil phase was oleic acid ethyl ester; Emulsifier was OP emulsifier; Auxiliary emulsifier was polyethylene glycol(peg) 400; The quantity of emulsifier to auxiliary emulsifier was the ratio of 5: 1; Microemulsion prescription was water-oleic acid ethyl ester-mixed emulsifier (0.45:0.1:0.45). The optimum extraction process was: time for 12.5 min, temperature of 52 degrees C, power of 360 W, frequency of 400 kHz, and the liquid-solid ratio of 40:1. The extraction rate of curcuminoids was 92.17% and 86.85% in microemulsion and oil phase, respectively. Curcuminoids is soluble in this microemulsion prescription with good extraction rate. This method is simple and suitable for curcuminoids extraction from Curcuma longa rhizome.

  9. A propofol microemulsion with low free propofol in the aqueous phase: formulation, physicochemical characterization, stability and pharmacokinetics.

    Science.gov (United States)

    Cai, WeiHui; Deng, WanDing; Yang, HuiHui; Chen, XiaoPing; Jin, Fang

    2012-10-15

    The purpose of this study was to develop a propofol microemulsion with a low concentration of free propofol in the aqueous phase. Propofol microemulsions were prepared based on single-factor experiments and orthogonal design. The optimal microemulsion was evaluated for pH, osmolarity, particle size, zeta potential, morphology, free propofol in the aqueous phase, stability, and pharmacokinetics in beagle dogs, and comparisons made with the commercial emulsion, Diprivan(®). The pH and osmolarity of the microemulsion were similar to those of Diprivan(®). The average particle size was 22.6±0.2 nm, and TEM imaging indicated that the microemulsion particles were spherical in appearance. The concentration of free propofol in the microemulsion was 21.3% lower than that of Diprivan(®). Storage stability tests suggested that the microemulsion was stable long-term under room temperature conditions. The pharmacokinetic profile for the microemulsion showed rapid distribution and elimination compared to Diprivan(®). We conclude that the prepared microemulsion may be clinically useful as a potential carrier for propofol delivery. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Multinuclear NMR characterization of CTAB-hexanol-water, sodium oleate-butanol-water and triton X-100-decanol-water microemulsions

    International Nuclear Information System (INIS)

    Nagy, J.B.; Bodart-Ravet, I.; Derouane, E.G.; Gourgue, A.; Verfaillie, J.P.

    1989-01-01

    Multinuclear NMR is a very valuable tool to characterize micellar systems or microemulsions. It allows one to determine c.m.c. values, to study the dissolution of organic molecules, the solvation of cations and anions, the structural changes occurring in a ternary diagram, the mobility of the molecules, etc. This review paper essentially deals with the characterization of cationic (CTAB-hexanol-water), anionic (sodium oleate-butanol-water) and neutral (Triton X-100-decanol-water) reversed micelles. The use of paramagnetic ions [Ni(II), CO(II), Fe(III), etc.] is particularly emphasized to characterize the site of solubilization and their interaction with surfactant and cosurfactant molecules 13 C-NMR). It is concluded, that the metallic ions are basically solvated in the inner water cores and one or more hexanol molecules are included in their first coordination shells in the CTAB-hexanol-water microemulsions. In the Triton X-100-decanol-water microemulsions, both decanol and Triton X-100 molecules enter the first coordination shell of Co(II) ions which are dissolved in both aqeous water cores and the organic medium. 19 F-NMR of a fluorinated probe molecule is particularly useful to study the size of the inner water cores. The method is based on the partition of the molecules between the interface and the organic medium. However, this method has to be applied with great care, and the computed data have to be compared to other physico-chemical results. Both 19 F- and 23 Na-NMR results show a great variation of the behaviour of the sodium oleate-butanol-water system in the so-called bicontinuous region. The Na + ions are oriented independently on a hypothetical inverse micellar droplet. (author). 43 refs.; 18 figs.; 7 tabs

  11. Syntheses of crosslinked latex nanoparticles using differential microemulsion polymerization

    Science.gov (United States)

    Hassmoro, N. F.; Rusop, M.; Abdullah, S.

    2013-06-01

    The differential microemulsion polymerization was used to synthesize latex nanoparticles. In this paper, 1, 3-butylene glycol dimethacrylate (1, 3-BGDMA) was used as a crosslinker respectively 1-5 weight% of monomer total. Butyl acrylate (BA), butyl methacrylate (BMA), and methacrylic acid (MAA) was used as the monomer. The thin film of latex nanoparticles were prepared by using spin coating method and have been dried at 100°C for 5 minutes. The amount of the crosslinker added in the polymerization was optimized and we found that the particle sizes fall in the range of 30-60 nm. The structural morphology of the uncrosslinked latex represented the most homogeneous image compared to the crosslinked latex. The effect of the amount of crosslinker on the particle sizes investigated by the Zeta-sizer Nano series while Atomic Force microscopy (AFM) was used to study the structural properties of latex nanoparticles.

  12. Syntheses of crosslinked latex nanoparticles using differential microemulsion polymerization

    International Nuclear Information System (INIS)

    Hassmoro, N F; Abdullah, S; Rusop, M

    2013-01-01

    The differential microemulsion polymerization was used to synthesize latex nanoparticles. In this paper, 1, 3-butylene glycol dimethacrylate (1, 3-BGDMA) was used as a crosslinker respectively 1–5 weight% of monomer total. Butyl acrylate (BA), butyl methacrylate (BMA), and methacrylic acid (MAA) was used as the monomer. The thin film of latex nanoparticles were prepared by using spin coating method and have been dried at 100°C for 5 minutes. The amount of the crosslinker added in the polymerization was optimized and we found that the particle sizes fall in the range of 30–60 nm. The structural morphology of the uncrosslinked latex represented the most homogeneous image compared to the crosslinked latex. The effect of the amount of crosslinker on the particle sizes investigated by the Zeta-sizer Nano series while Atomic Force microscopy (AFM) was used to study the structural properties of latex nanoparticles.

  13. Use of micro-emulsions in liquid-liquid extraction

    International Nuclear Information System (INIS)

    Komornicki, Jacques

    1982-01-01

    As liquid-liquid extraction of metallic cations is an important method of separation and concentration of metals present in diluted aqueous solutions, and as the extraction rate is limited by one or several steps of matter transfer at the liquid-liquid interface, the extraction kinetics can be improved by creating a wide surface interface and by allowing an increased reactivity between species. In this research thesis, the author aims at determining to which extent systems of interface with a wide surface obtained by using for example amphiphile molecules to create micro-emulsions, can be used as reaction media for physical-chemical processes of liquid-liquid extraction. He also aims at identifying their applicability limitations and problems which might arise with their application. The author notably focuses of the liquid-liquid extraction of metallic cations exhibiting particularly slow extraction kinetics

  14. Synthesis of polyalkylacrylate nanolatexes by microemulsion polymerization method

    Directory of Open Access Journals (Sweden)

    A.M. Al-Sabagh

    2012-12-01

    Full Text Available The paper concerns with the radical polymerization of [octadecyl acrylate (ODA, isooctyl acrylate (iso-OA and α-olefins 1-Octene (n-O]. These microemulsions were stabilized by sodium dodecyl sulfate (SDS and initiated by water-soluble initiator potassium persulfate (KPS. The nanolatex particle sizes were determined by transmission electron microscope (TEM. They were situated between 10 and 100 nm. The microstructures were confirmed by FT-IR and molecular weights determined by Gel permeation chromatography (GPC. The obtained M. wt. were (≈70 × 103, 101 × 103 and 153 × 103 g/mol. The polydispersity, molecular weights, and particle sizes were discussed in the light of micelle formation and shape of the alkyl group via emulsion polymerization.

  15. A modified microemulsion method for fabrication of hydrogel Tragacanth nanofibers.

    Science.gov (United States)

    Ghayempour, Soraya; Montazer, Majid

    2018-04-09

    Tragacanth is a nontoxic, biodegradable and biocompatible polymer applied as a nanostructure form in various fields such as biomedicine and food industry. Here, hydrogel Tragacanth nanofibers were fabricated using a modified microemulsion method. The effective parameters on the fabrication of nanofibers such as emulsifier type, stirrer type, processing time and concentrations of emulsifier, Tragacanth and aluminum chloride were studied and the conditions were optimized for high quality nanofibers. SEM images indicated Tragacanth nanofiberswere successfully synthesized with average diameter of 50 nm and uniformdistribution. Appear a peak at 1110 cm -1 related to Al-C bonds and reduce intensity ofthe peaks at 1742 and 1629 cm -1 and in FT-IR spectrum of nanofibersprove the successfully synthesis. Further, the hydrogel properties of the synthesized nanofibers can be proved by the swelling of 142% and drying time of 3 h. Copyright © 2018 Elsevier B.V. All rights reserved.

  16. A Thermal Degradation (Thermolysis) Study of Rotenone Extracted from Derris elliptica Roots Using Reverse-Phase High Performance Liquid Chromatography (RP-HPLC)

    International Nuclear Information System (INIS)

    Saiful Irwan Zubairi; Mohamad Roji Sarmidi; Ramlan Abdul Aziz

    2015-01-01

    Bio-pesticides are becoming increasingly important as pest management tools in various cropping systems in the tropics essentially to remedy problems associated with the indiscriminate use of hard and non-environmental friendly inorganic pesticide. In these past few decades, many bio-pesticidal products, both microbial-based (bacteria, fungi, microsprodia, entomopathogenic nematodes and viruses) and plant-based botanicals (rotenone and azadiracthin) have been studied for their use against insect pests in the tropics. In this study, the effects of the concentration process with respect to the yield of rotenone (mg) and its concentration (mg/mL) are presented extensively. The raw plants were collected from Kota Johor Lama, Johor and sorted to obtain the roots and stems. Only the roots and stems were utilized as raw materials of the extraction process. The rotenone from roots and stems was extracted using the normal soaking extraction (NSE) at 28 to 30 degree Celsius with 95 % (v/v) of acetone as a solvent and the solvent-to-solid ratio of 10 mL/ g. The extraction was carried out for 24 h. Next, the liquid crude extract was concentrated using the rotary evaporator at 50 degree Celsius and 80 mbar of vacuum pressure to remove approximately 90 % of solvent. The fractions of the liquid crude extract were collected (15 min/ mL/ fraction), diluted (1/100 with acetone) and cleaned up (to remove any fine debris) prior to determination of rotenone content (mg) and concentration (mg/mL) by using the reverse-phase high performance liquid chromatography (RP-HPLC). Finally, the results showed that there was a significant effect of thermal degradation or dissipation of rotenone content at higher operating temperature (greater than 40 degree Celsius) with a rapid rotenone reduction for the first 15 min of exposure. The possibilities for better exploitation and identification of the effective operating parameters based on the above mentioned results will be perhaps discussed in the

  17. Improving the reversibility of thermal denaturation and catalytic efficiency of Bacillus licheniformis α-amylase through stabilizing a long loop in domain B.

    Directory of Open Access Journals (Sweden)

    Zhu Li

    Full Text Available The reversibility of thermal denaturation and catalytic efficiency of Bacillus licheniformis α-amylase were improved through site-directed mutagenesis. By using multiple sequence alignment and PoPMuSiC algorithm, Ser187 and Asn188, which located within a long loop in Domain B of Bacillus licheniformis α-amylase, were selected for mutation. In addition, Ala269, which is adjacent to Ser187 and Asn188, was also investigated. Seven mutants carrying the mutations S187D, N188T, N188S, A269K, A269K/S187D, S187D/N188T, and A269K/S187D/N188T were generated and characterized. The most thermostable mutant, A269K/S187D/N188T, exhibited a 9-fold improvement in half-life at 95°C and pH 5.5, compared with that of the wild-type enzyme. Mutant A269K/S187D/N188T also exhibited improved catalytic efficiency. The catalytic efficiency of mutant A269K/S187D/N188T reached 5.87×103±0.17 g·L-1·s-1 at pH 5.5, which is 1.84-fold larger than the corresponding value determined for the wild-type enzyme. Furthermore, the structure analysis showed that immobilization of the loop containing Ser187 and Asn188 plays a significant role in developing the properties of Bacillus licheniformis α-amylase.

  18. Improving the reversibility of thermal denaturation and catalytic efficiency of Bacillus licheniformis α-amylase through stabilizing a long loop in domain B.

    Science.gov (United States)

    Li, Zhu; Duan, Xuguo; Chen, Sheng; Wu, Jing

    2017-01-01

    The reversibility of thermal denaturation and catalytic efficiency of Bacillus licheniformis α-amylase were improved through site-directed mutagenesis. By using multiple sequence alignment and PoPMuSiC algorithm, Ser187 and Asn188, which located within a long loop in Domain B of Bacillus licheniformis α-amylase, were selected for mutation. In addition, Ala269, which is adjacent to Ser187 and Asn188, was also investigated. Seven mutants carrying the mutations S187D, N188T, N188S, A269K, A269K/S187D, S187D/N188T, and A269K/S187D/N188T were generated and characterized. The most thermostable mutant, A269K/S187D/N188T, exhibited a 9-fold improvement in half-life at 95°C and pH 5.5, compared with that of the wild-type enzyme. Mutant A269K/S187D/N188T also exhibited improved catalytic efficiency. The catalytic efficiency of mutant A269K/S187D/N188T reached 5.87×103±0.17 g·L-1·s-1 at pH 5.5, which is 1.84-fold larger than the corresponding value determined for the wild-type enzyme. Furthermore, the structure analysis showed that immobilization of the loop containing Ser187 and Asn188 plays a significant role in developing the properties of Bacillus licheniformis α-amylase.

  19. Reverse Osmosis

    Indian Academy of Sciences (India)

    many applications, one of which is desalination of seawater. The inaugural Nobel Prize in Chemistry was awarded in 1901 to van 't Hoff for his seminal work in this area. The present article explains the principle of osmosis and reverse osmosis. Osmosis and Reverse Osmosis. As the name suggests, reverse osmosis is the ...

  20. Determination of mercury in gasoline by cold vapor atomic absorption spectrometry with direct reduction in microemulsion media

    Energy Technology Data Exchange (ETDEWEB)

    Brandao, Geisamanda Pedrini [Department of Chemistry, Pontifical Catholic University of Rio de Janeiro, Rua Marques de S. Vicente, 225, Gavea, 22453-900, Rio de Janeiro, RJ (Brazil); Calixto de Campos, Reinaldo [Department of Chemistry, Pontifical Catholic University of Rio de Janeiro, Rua Marques de S. Vicente, 225, Gavea, 22453-900, Rio de Janeiro, RJ (Brazil)]. E-mail: rccampos@rdc.puc-rio.br; Luna, Aderval Severino [Department of Analytical Chemistry, Rio de Janeiro State University, Rua S. Francisco Xavier, s/n, Maracana, 20550-900, Rio de Janeiro, RJ (Brazil)

    2005-06-30

    The determination of Hg in gasoline by cold vapor atomic absorption spectrometry, after direct aqueous NaBH{sub 4} reduction in a three-component (microemulsion) medium, was investigated. Microemulsions were prepared by mixing gasoline with propan-1-ol and 50% v / v HNO{sub 3} at a 20 : 15 : 1 volume ratio. A long-term homogeneous system was immediately formed this way. After reduction, the Hg vapor generated in a reaction flask was transported to an intermediate K{sub 2}Cr{sub 2}O{sub 7}/H{sub 2}SO{sub 4} trap solution in order to avoid poisoning of the Au-Pt trap by the gasoline vapors. A second reduction step was then conducted and the generated Hg vapor transported to the Au-Pt trap, followed by thermal release of Hg{sup 0} and atomic absorption measurement. Purified N{sub 2} was used as purge and transport gas. After multivariate optimization by central composite design calibration graphs showed coefficients of correlation of 0.9999 and a characteristic mass of 2 ng was obtained. Typical coefficients of variation of 5% and 6% were found for ten consecutive measurements at concentration levels of 1 and 8 {mu}g L{sup -1} of Hg{sup 2+}, respectively. The limit of detection was 0.10 {mu}g L{sup -1} (0.14 {mu}g kg{sup -1}) in the original sample. A total measurement cycle took 11 min, permitting duplicate analysis of 3 samples per hour. The results obtained with the proposed procedure in the analysis of commercial gasoline samples were in agreement with those obtained by a comparative procedure. Gasoline samples of the Rio de Janeiro city have shown Hg concentrations below 0.27 {mu}g L{sup -1}.

  1. Thermosensory reversal effect quantified

    NARCIS (Netherlands)

    Bergmann Tiest, W.M.; Kappers, A.M.L.

    2008-01-01

    At room temperature, some materials feel colder than others due to differences in thermal conductivity, heat capacity and geometry. When the ambient temperature is well above skin temperature, the roles of 'cold' and 'warm' materials are reversed. In this paper, this effect is quantified by

  2. Thermosensory reversal effect quantified

    NARCIS (Netherlands)

    Bergmann Tiest, W.M.; Kappers, A.M.L.

    2008-01-01

    At room temperature, some materials feel colder than others due to differences in thermal conductivity, heat capacity and geometry. When the ambient temperature is well above skin temperature, the roles of ‘cold’ and ‘warm’ materials are reversed. In this paper, this effect is quantified by

  3. A Novel Paclitaxel Microemulsion Containing a Reduced Amount of Cremophor EL: Pharmacokinetics, Biodistribution, and In Vivo Antitumor Efficacy and Safety

    Science.gov (United States)

    Wang, Ying; Wu, Ke-Chun; Zhao, Bing-Xiang; Zhao, Xin; Wang, Xin; Chen, Su; Nie, Shu-Fang; Pan, Wei-San; Zhang, Xuan; Zhang, Qiang

    2011-01-01

    The purpose of this study was to prepare a novel paclitaxel (PTX) microemulsion containing a reduced amount of Cremophor EL (CrEL) which had similar pharmacokinetics and antitumor efficacy as the commercially available PTX injection, but a significantly reduced allergic effect due to the CrEL. The pharmacokinetics, biodistribution, in vivo antitumor activity and safety of PTX microemulsion was evaluated. The results of pharmacokinetic and distribution properties of PTX in the microemulsion were similar to those of the PTX injection. The antitumor efficacy of the PTX microemulsion in OVCRA-3 and A 549 tumor-bearing animals was similar to that of PTX injection. The PTX microemulsion did not cause haemolysis, erythrocyte agglutination or simulative reaction. The incidence and degree of allergic reactions exhibited by the PTX microemulsion group, with or without premedication, were significantly lower than those in the PTX injection group (P microemulsion had similar pharmacokinetics and anti-tumor efficacy to the PTX injection, but a significantly reduced allergic effect due to CrEL, indicating that the PTX microemulsion overcomes the disadvantages of the conventional PTX injection and is one way of avoiding the limitations of current injection product while providing suitable therapeutic efficacy. PMID:21331356

  4. Transdermal delivery of diclofenac using water-in-oil microemulsion: formulation and mechanistic approach of drug skin permeation.

    Science.gov (United States)

    Thakkar, Priyanka J; Madan, Parshotam; Lin, Senshang

    2014-05-01

    The objective of the present investigation was to enhance skin permeation of diclofenac using water-in-oil microemulsion and to elucidate its skin permeation mechanism. The w/o microemulsion formulations were selected based on constructed pseudoternary phase diagrams depending on water solubilization capacity and thermodynamic stability. These formulations were also subjected to physical characterization based on droplet size, viscosity, pH and conductivity. Permeation of diclofenac across rat skin using side-by-side permeation cells from selected w/o microemulsion formulations were evaluated and compared with control formulations. The selected w/o microemulsion formulations were thermodynamically stable, and incorporation of diclofenac sodium into microemulsion did not affect the phase behavior of system. All microemulsion formulations had very low viscosity (11-17 cps) and droplet size range of 30-160 nm. Microemulsion formulations exhibited statistically significant increase in diclofenac permeation compared to oily solution, aqueous solution and oil-Smix solution. Higher skin permeation of diclofenac was observed with low Smix concentration and smaller droplet size. Increase in diclofenac loading in aqueous phase decreased the partition of diclofenac. Diclofenac from the oil phase of microemulsion could directly partition into skin, while diclofenac from the aqueous droplets was carried through skin by carrier effect.

  5. Evaluation of cinnamon essential oil microemulsion and its vapor phase for controlling postharvest gray mold of pears (Pyrus pyrifolia).

    Science.gov (United States)

    Wang, Yifei; Zhao, Ruipeng; Yu, Ling; Zhang, Yunbin; He, Yan; Yao, Jie

    2014-03-30

    Essential oil of cinnamon (CM) is a potential alternative to chemical fungicides. Thus this work aimed to investigate the possible effects of CM microemulsions on decay developments and qualitative properties of pears. The decay incidence of samples treated with 500 µg L⁻¹ microemulsion was significantly reduced by 18.7% in comparison to that of 500 µg L⁻¹ non-microemulsion after 4 days' storage at 20 °C. In the vapor phase, the CM microemulsion with the lowest concentration had the best control for decay incidence and lesion diameter. The interval between inoculations also influenced decay development. Pears treated with Botrytis cinerea and immediately followed by CM microemulsion showed the lowest decay incidence. Moreover, in the natural decay experiment, the percentage of rotted pears was 3.8% in the CM microemulsion treatment and 5.8% in the control. CM microemulsion delayed the loss of ascorbic acid, yet it had no significant influence on pear qualities such as firmness and color. CM microemulsion may be an alternative way to control the gray mold of pears without a negative influence on its qualities. © 2013 Society of Chemical Industry.

  6. Transdermal delivery of hydrophobic and hydrophilic local anesthetics from o/w and w/o Brij 97-based microemulsions

    DEFF Research Database (Denmark)

    Junyaprasert, Varaporn Buraphacheep; Boonme, Prapaporn; Songkro, Sarunyoo

    2007-01-01

    To characterize the physicochemical properties of drug-loaded oil-in-water (o/w) and water-in-oil (w/o) Brij 97-based microemulsions in comparison to their blank counterparts and to investigate the influence of microemulsion type on in vitro skin permeation of model hydrophobic drugs...

  7. Formation mechanism of CdS nanoparticles with tunable luminescence via a non-ionic microemulsion route

    International Nuclear Information System (INIS)

    Angelescu, Daniel G.; Munteanu, Gabriel; Anghel, Dan F.; Peretz, Sandu; Maraloiu, Adrian V.; Teodorescu, Valentin S.

    2013-01-01

    We investigated the synthesis of CdS nanoparticles via an optimized water-in-oil microemulsion route that used the non-ionic surfactant-based system H 2 O–n-octane–Brij30/1-octanol. For that purpose, a microemulsion that contained Cd(II) ions (μe1) and another microemulsion that contained S 2− ions (μe2) were combined. To investigate the ways in which the non-ionic microemulsion characteristics controlled the size and emission properties of colloidal CdS quantum dots, μe1 and μe2 with tunable and robust similar structure were prepared. This requirement was fulfilled by matching the water emulsification failure boundary (wefb) of the two microemulsions and carrying out synthesis along this boundary. Dynamic light scattering and fluorescence probe techniques were used to investigate the size and interfacial organization of the microemulsion water droplets, and the CdS nanoparticles were characterized by UV–Vis and static fluorescence spectrometry, TEM and HRTEM. Nanoparticles of diameter 4.5–5.5 nm exhibiting enhanced band edge emission were produced by increasing the water content of the precursor microemulsions. The experimental results were combined with a Monte Carlo simulation approach to demonstrate that growth via coagulation of seed nuclei represented the driving mechanism for the CdS nanoparticle formation in the water-in-oil microemulsion.

  8. Formation mechanism of CdS nanoparticles with tunable luminescence via a non-ionic microemulsion route

    Energy Technology Data Exchange (ETDEWEB)

    Angelescu, Daniel G., E-mail: dangelescu@hotmail.com; Munteanu, Gabriel [Quantum Chemistry and Molecular Structure Laboratory, Romanian Academy, ' Ilie Murgulescu' Institute of Physical Chemistry (Romania); Anghel, Dan F.; Peretz, Sandu [Romanian Academy, ' Ilie Murgulescu' Institute of Physical Chemistry, Colloidal Laboratory (Romania); Maraloiu, Adrian V.; Teodorescu, Valentin S. [National Institute of Materials Physics, Institute of Atomic Physics (Romania)

    2013-01-15

    We investigated the synthesis of CdS nanoparticles via an optimized water-in-oil microemulsion route that used the non-ionic surfactant-based system H{sub 2}O-n-octane-Brij30/1-octanol. For that purpose, a microemulsion that contained Cd(II) ions ({mu}e1) and another microemulsion that contained S{sup 2-} ions ({mu}e2) were combined. To investigate the ways in which the non-ionic microemulsion characteristics controlled the size and emission properties of colloidal CdS quantum dots, {mu}e1 and {mu}e2 with tunable and robust similar structure were prepared. This requirement was fulfilled by matching the water emulsification failure boundary (wefb) of the two microemulsions and carrying out synthesis along this boundary. Dynamic light scattering and fluorescence probe techniques were used to investigate the size and interfacial organization of the microemulsion water droplets, and the CdS nanoparticles were characterized by UV-Vis and static fluorescence spectrometry, TEM and HRTEM. Nanoparticles of diameter 4.5-5.5 nm exhibiting enhanced band edge emission were produced by increasing the water content of the precursor microemulsions. The experimental results were combined with a Monte Carlo simulation approach to demonstrate that growth via coagulation of seed nuclei represented the driving mechanism for the CdS nanoparticle formation in the water-in-oil microemulsion.

  9. Thermal and UV stability of β-carotene dissolved in peppermint oil microemulsified by sunflower lecithin and Tween 20 blend.

    Science.gov (United States)

    Chen, Huaiqiong; Zhong, Qixin

    2015-05-01

    Microemulsions are suitable for simultaneous delivery of flavour oils and lipophilic bioactive compounds in transparent beverages. In the present study, the feasibility of delivering β-carotene in microemulsions formulated with peppermint oil and a blend of Tween® 20 and various amounts of sunflower lecithin was investigated. The poorly water- and oil-soluble β-carotene was dissolved in the transparent microemulsions that had particles smaller than 10nm and were stable during ambient storage for 65 d. The inclusion of β-carotene did not change the flow-behaviour and Newtonian viscosity. The degradation of β-carotene in microemulsions during ambient storage, ultraviolet radiation, and thermal treatments at 60 and 80 °C followed first order kinetics and was greatly suppressed when compared to the solution control. The antioxidant potential of peppermint oil and a greater content of lecithin in microemulsions enabled the better protection of β-carotene. The studied microemulsions may find various applications in manufacturing transparent beverages. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Stability assessment of lycopene microemulsion prepared using tomato industrial waste against various processing conditions.

    Science.gov (United States)

    Amiri-Rigi, Atefeh; Abbasi, Soleiman

    2017-11-01

    Green separation techniques are growing at a greater rate than solvent extraction as a result of the constant consumer drive to 'go natural'. Considering the increasing evidence of the health benefits of lycopene and massive tomato industrial waste, in the present study, lycopene was extracted from tomato industrial waste using microemulsion technique and its mean droplet size and size distribution was determined. Moreover, the effects of pasteurization, sterilization, freeze-thaw cycles and ultraviolet (UV) irradiation on the thermodynamic stability, turbidity and lycopene concentration of the lycopene microemulsion were monitored. Freeze-thaw cycles, pasteurization and short exposure to UV irradiation showed no or negligible influence on lycopene content and turbidity of the microemulsion. However, long exposure to UV (260 min) reduced the lycopene content and turbidity by 34% and 10%, respectively. HHST (higher-heat shorter-time) and sterilization also reduced lycopene content (25%) and increased turbidity (32%). The lycopene microemulsion showed satisfactory stability over a process where its monodispersity and nanosize could be of potential advantage to the food and related industries. Regarding the carcinogenicity of synthetic colourants, potential applications of the lycopene microemulsion include in soft drinks and minced meat, which would result in a better colour and well-documented health-promoting qualities. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  11. Optimizing the dermal accumulation of a tazarotene microemulsion using skin deposition modeling.

    Science.gov (United States)

    Nasr, Maha; Abdel-Hamid, Sameh

    2016-01-01

    It is well known that microemulsions are mainly utilized for their transdermal rather than their dermal drug delivery potential due to their low viscosity, and the presence of penetration enhancing surfactants and co-surfactants. Applying quality by design (QbD) principles, a tazarotene microemulsion formulation for local skin delivery was optimized by creating a control space. Critical formulation factors (CFF) were oil, surfactant/co-surfactant (SAA/CoS), and water percentages. Critical quality attributes (CQA) were globular size, microemulsion viscosity, tazarotene skin deposition, permeation, and local accumulation efficiency index. Increasing oil percentage increased globular size, while the opposite occurred regarding SAA/CoS, (p = 0.001). Microemulsion viscosity was reduced by increasing oil and water percentages (p microemulsion viscosity, and drug deposition. A combination of 40% oil and 45% SAA/CoS showed the maximum drug deposition of 75.1%. Clinical skin irritation study showed that the aforementioned formula was safe for topical use. This article suggests that applying QbD tools such as experimental design is an efficient tool for drug product design.

  12. Collagen and hyaluronic acid hydrogel in water-in-oil microemulsion delivery systems.

    Science.gov (United States)

    Kupper, Sylwia; Kłosowska-Chomiczewska, Ilona; Szumała, Patrycja

    2017-11-01

    The increase in skin related health issues has promoted interest in research on the efficacy of microemulsion in dermal and transdermal delivery of active ingredients. Here, we assessed the water-in-oil microemulsion capacity to incorporate two natural polymers, i.e. collagen and hyaluronic acid with low and high molecular weight. Systems were extensively characterized in terms of conductivity, phase inversion studies, droplet diameter, polydispersity index and rheological properties. The results of this research indicate that the structure and extent of water phase in microemulsions is governed by ratio and amount of surfactant mixture (sorbitan ester derivatives). However, results have also shown that collagen, depending upon the weight of the molecule and its surface activity, influence the droplet size of the microemulsions. While the hyaluronic acid, especially with high molecular weight, due to the water-binding ability and hydrogel formation alters the rheological properties of the microemulsion, thus providing viscous consistency of the formulation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. In vitro and in vivo evaluation of capsaicin-loaded microemulsion for enhanced oral bioavailability.

    Science.gov (United States)

    Zhu, Yuan; Zhang, Jiajia; Zheng, Qianfeng; Wang, Miaomiao; Deng, Wenwen; Li, Qiang; Firempong, Caleb Kesse; Wang, Shengli; Tong, Shanshan; Xu, Ximing; Yu, Jiangnan

    2015-10-01

    Capsaicin, as a food additive, has attracted worldwide concern owing to its pungency and multiple pharmacological effects. However, poor water solubility and low bioavailability have limited its application. This study aims to develop a capsaicin-loaded microemulsion to enhance the oral bioavailability of the anti-neuropathic-pain component, capsaicin, which is poorly water soluble. In this study, the microemulsion consisting of Cremophor EL, ethanol, medium-chain triglycerides (oil phase) and water (external phase) was prepared and characterized (particle size, morphology, stability and encapsulation efficiency). The gastric mucosa irritation test of formulated capsaicin was performed in rats to evaluate its oral feasibility, followed by the pharmacokinetic study in vivo. Under these conditions, the encapsulated capsaicin revealed a faster capsaicin release in vitro coupled with a greater absorption in vivo when compared to the free capsaicin. The oral bioavailability of the formulated capsaicin-loaded microemulsions was 2.64-fold faster than that of free capsaicin. No significant irritation was observed on the mucosa from the pathological section of capsaicin-loaded microemulsion treated stomach. These results indicate that the developed microemulsion represents a safe and orally effective carrier for poorly soluble substances. The formulation could be used for clinical trials and expand the application of capsaicin. © 2014 Society of Chemical Industry.

  14. Development and evaluation of a novel microemulsion formulation of elacridar to improve its bioavailability

    Science.gov (United States)

    Sane, Ramola; Mittapalli, Rajendar K.; Elmquist, William F.

    2014-01-01

    The study objective was to develop a formulation of elacridar to overcome its dissolution-rate limited bioavailability. Elacridar is a P-gp and BCRP inhibitor that has been used to improve the brain distribution of drugs that are substrates of P-gp and BCRP. The chronic use of elacridar is restricted due to poor solubility leading to poor oral bioavailability. A microemulsion formulation using Cremophor EL, Carbitol and Captex 355 (6:3:1) was developed. The elacridar microemulsion was effective in the inhibition of P-gp and Bcrp in MDCKII-transfected cells. FVBn mice were used to determine the bioavailability of elacridar after a 10 mg/kg dose of elacridar in the microemulsion, intraperitoneally and orally; and the absolute bioavailability was determined to be 1.3 and 0.47, respectively. Co-administration of elacridar microemulsion intraperitoneally with oral erlotinib in FVBn mice improved the erlotinib brain penetration three-fold. The current study shows that a microemulsion formulation of elacridar is effective in improving the bioavailability of elacridar and is an effective inhibitor of P-gp and Bcrp; in-vitro and in-vivo. It offers an alternative to the suspension and allows a decrease in the dose required to achieve a significant inhibitory effect at the blood-brain barrier. PMID:23334925

  15. Microemulsion-Based Mucoadhesive Buccal Wafers: Wafer Formation, In Vitro Release, and Ex Vivo Evaluation.

    Science.gov (United States)

    Pham, Minh Nguyet; Van Vo, Toi; Tran, Van-Thanh; Tran, Phuong Ha-Lien; Tran, Thao Truong-Dinh

    2017-10-01

    Microemulsion has the potentials to enhance dissolution as well as facilitate absorption and permeation of poorly water-soluble drugs through biological membranes. However, its application to govern a controlled release buccal delivery for local treatment has not been discovered. The aim of this study is to develop microemulsion-based mucoadhesive wafers for buccal delivery based on an incorporation of the microemulsion with mucoadhesive agents and mannitol. Ratio of oil to surfactant to water in the microemulsion significantly impacted quality of the wafers. Furthermore, the combination of carbopol and mannitol played a key role in forming the desired buccal wafers. The addition of an extra 50% of water to the formulation was suitable for wafer formation by freeze-drying, which affected the appearance and distribution of carbopol in the wafers. The amount of carbopol was critical for the enhancement of mucoadhesive properties and the sustained drug release patterns. Release study presented a significant improvement of the drug release profile following sustained release for 6 h. Ex vivo mucoadhesive studies provided decisive evidence to the increased retention time of wafers along with the increased carbopol content. The success of this study indicates an encouraging strategy to formulate a controlled drug delivery system by incorporating microemulsions into mucoadhesive wafers.

  16. Microemulsion based on Pterodon emarginatus oil and its anti-inflammatory potential

    Directory of Open Access Journals (Sweden)

    Henrique Pascoa

    2015-03-01

    Full Text Available This article reports the development of a pharmaceutical product containing vegetable actives from a Brazilian medicinal plant. The possibility of forming a microemulsion using Pterodon emarginatus ("sucupira" oil was evaluated and the anti-inflammatory potential of this microemulsion was also examined. A formulation was developed using P. emarginatus oil, a mixture of ethoxylated Castor Oil (Ultramone(r R-540/propylene glycol 2:1 (surfactant/cosurfactant and distilled water at a ratio of 10:15:75, respectively. The microemulsion which was selected was then subjected to the preliminary stability test and analyzed in terms of average diameter of droplets, pH, zeta potential, and polydispersity index, on the 1st, 7th, 15th, and 30th days after preparation and stored at different temperatures (5 ± 2 °C, 25 ± 2 °C, and 40 ± 2 °C. The anti-inflammatory in vivo activity of both oil and formulation were evaluated, using the experimental model of croton oil-induced ear edema. The preliminary stability test showed that the microemulsion stored at 5 and 25 °C retained its original features throughout the 30-day period. The anti-inflammatory potential of both oil and formulation was shown to be statistically significant (p < 0.001, when compared to the control group, however, the microemulsion proved to be more effective (p < 0.05 than the oil when applied directly to the ear.

  17. The novel oral imatinib microemulsions: physical properties, cytotoxicity activities and improved Caco-2 cell permeability.

    Science.gov (United States)

    Gundogdu, Evren; Karasulu, Hatice Yesim; Koksal, Cinel; Karasulu, Ercüment

    2013-01-01

    The objective of this study was to formulate imatinib (IM) loaded to water-in-oil (w/o) microemulsions as an alternative formulation for cancer therapy and to evaluate the cytotoxic effect of microemulsions Caco-2 and MCF-7. Moreover, permeability studies were also performed with Caco-2 cells. W/o microemulsion systems were developed by using pseudo-ternary phase diagram. According to cytotoxicity studies, all formulations did not exert a cytotoxic effect on Caco-2 cells. Furthermore, all formulations had a significant cytotoxic effect on MCF-7 cells and the cytotoxic effect of M3IM was significantly more than that of other microemulsions and IM solution (p < 0.05). The permeability studies of IM across Caco-2 cells showed that permeability value from apical to basolateral was higher than permeability value of other formulations. In conclusion, the microemulsion formulations as a drug carrier, especially M3IM formulation, may be used as an effective alternative breast cancer therapy for oral delivery of IM.

  18. Behavior of microemulsion systems of virgin coconut oil (VCO) using igepal CO-520 and tween 80 surfactant

    Science.gov (United States)

    Safuan, A.; Hamdan, S.; Laili, C. R.

    2017-09-01

    Virgin Coconut Oil (VCO) has been applied in many application and products. Formation of microemulsion region with surfactant was investigated by using phase diagram. The surfactants used are igepal CO-520 and tween 80. The studies showed that formation of microemulsion region were dependent on the behaviour of the surfactant toward VCO. The result showed that microemulsion regions were present in igepal CO-520 system formed a larger water-in-oil microemulsion region compared to tween 80 system. Certain weight ratios of VCO to surfactants were studied by using evaporation test in order to study the water loss of the microemulsion in ambient condition. The evaporation rate of samples was varies depending their compositon of VCO, surfactant and water.

  19. Assessment of Aprotinin Loaded Microemulsion Formulations for Parenteral Drug Delivery: Preparation, Characterization, in vitro Release and Cytotoxicity Studies.

    Science.gov (United States)

    Okur, Neslihan Üstündağ; Özdemir, Derya İlem; Kahyaoğlu, Şennur Görgülü; Şenyiğit, Zeynep Ay; Aşıkoğlu, Makbule; Genç, Lütfi; Karasulu, H Yeşim

    2015-01-01

    The object of the current study was to prepare novel microemulsion formulations of aprotinin for parenteral delivery and to compare in vitro characteristics and release behaviour of different Technetium-99m ((99m)Tc)-Aprotinin loaded microemulsion formulations. In addition, cytotoxicity of microemulsion formulation was evaluated with cell culture studies on human immortalized pancreatic duct epithelial-like cells. For this aim, firstly, pseudo-ternary phase diagrams were plotted to detect the formulation region and optimal microemulsions were characterized for their thermodynamic stability, conductivity, particle size, zeta potential, viscosity, pH and in vitro release properties. For in vitro release studies aprotinin was labelled with (99m)Tc and labelling efficiency, radiochemical purity and stability of the radiolabeled complex were determined by several chromatography techniques. Radiolabeling efficiency of (99m)Tc-Aprotinin was found over than 90% without any significant changes up to 6 hours after labelling at room temperature. After that, in vitro release studies of (99m)Tc-Aprotinin loaded microemulsions were performed with two different methods; dissolution from diffusion cells and dialysis bags. Both methods showed that release rate of (99m)Tc- Aprotinin from microemulsion could be controlled by microemulsion formulations. Drug release from the optimized microemulsion formulations was found lower compared to drug solution at the end of six hours. According to stability studies, the optimized formulation was found to be stable over a period of 12 months. Also, human immortalized pancreatic duct epithelial-like cells were used to evaluate the cytotoxicity of optimum formulation. Developed microemulsion did not reveal cytotoxicity. In conclusion the present study indicated that the M1-APT microemulsion is appropriate for intravenous application of aprotinin.

  20. Two-chiral-component microemulsion electrokinetic chromatography-chiral surfactant and chiral oil: part 1. dibutyl tartrate.

    Science.gov (United States)

    Kahle, Kimberly A; Foley, Joe P

    2007-06-01

    The first simultaneous use of a chiral surfactant and a chiral oil for microemulsion EKC (MEEKC) is reported. Six stereochemical combinations of dodecoxycarbonylvaline (DDCV: R, S, or racemic, 2.00% w/v), racemic 2-hexanol (1.65% v/v), and dibutyl tartrate (D, L, or racemic, 1.23% v/v) were examined as chiral pseudostationary phases (PSPs) for the separation of six pairs of pharmaceutical enantiomers: pseudoephedrine, ephedrine, N-methyl ephedrine, metoprolol, synephrine, and atenolol. Subtle differences were observed for three chromatographic figures of merit (alpha(enant), alpha(meth), k) among the chiral microemulsions; a moderate difference was observed for efficiency (N) and elution range. Dual-chirality microemulsions provided both the largest and smallest enantioselectivities, due to small positive and negative synergies between the chiral microemulsion components. For the ephedrine family of compounds, dual-chiral microemulsions with surfactant and oil in opposite stereochemical configurations provided higher enantioselectivities than the single-chiral component microemulsion (RXX), whereas dual-chiral microemulsions with surfactant and oil in the same stereochemical configurations provided lower enantioselectivities than RXX. Slight to moderate enantioselective synergies were confirmed using a thermodynamic model. Efficiencies observed with microemulsions comprised of racemic dibutyl tartrate or dibutyl-D-tartrate were significantly higher than those obtained with dibutyl-L-tartrate, with an average difference in plate count of about 25 000. Finally, one two-chiral-component microemulsion (RXS) provided significantly better resolution than the remaining one- and two-chiral-component microemulsions for the ephedrine-based compounds, but only slightly better or equivalent resolution for non-ephedrine compounds.

  1. Avalanche criticality in thermal-driven martensitic transitions: the asymmetry of the forward and reverse transitions in shape-memory materials

    Science.gov (United States)

    Planes, Antoni; Vives, Eduard

    2017-08-01

    Martensitic transitions take place intermittently as a sequence of avalanches which are accompanied by the emission of acoustic waves. The study of this acoustic emission (AE) reveals the scale-free nature of the avalanches. In a number of shape memory materials undergoing a martensitic transition it has been found that, in spite of relatively low hysteresis, the dynamics of forward and reverse transitions are different, which may explain the fact that the AE activity is different in both forward and reverse transitions. The asymmetry could be a consequence of the fact that, while nucleation is required for the transition from the parent to martensitic phase to take place, reverse transition occurs by fast shrinkage of martensitic domains. We have analysed in detail the distribution of avalanches in cooling and heating runs in Fe-Pd and Cu-Zn-Al shape-memory alloys. In the former, the martensitic transition is weakly first order while it shows a significant first order character in the latter. We have found that in Fe-Pd the distributions are power law for the forward and reverse transitions characterized by the same critical exponents. For Cu-Zn-Al the distribution of avalanches is critical in forward transitions but exponentially damped in the reverse transition. It is suggested that this different behaviour could originate from the different dynamic mechanisms in forward and reverse transitions. This paper is dedicated to our friend Ekhard Salje in the occasion of his 70th birthday.

  2. Synthesis of acrylated palm oil nanoparticles using microemulsion polymerization initiated by gamma ray

    International Nuclear Information System (INIS)

    Rida Tajau; Wan Md Zin Wan Yunus; Khairul Zaman Mohd Dahlan; Mohd Hilmi Mahmood; Kamaruddin Hashim; Sim, Flora; Sharila Muhd Faizal

    2010-01-01

    The use of microemulsion in the development of nanoparticle based on acrylated palm oil product is demonstrated. The microemulsion polymerization was initiated by gamma ray for synthesizing crosslinked nanoparticle. Polymerization of acrylated palm oil in three-component ionic microemulsions was prepared with sodium dodecyl sulphate (SDS) and water. The resulted nanoparticle, before and after initiated by gamma ray, were evaluated in terms of particle diameter, surface charge and molecular structure. Type and concentration of surfactants, monomer concentration, radiation dose and time of storage strongly affected the size, charge and size stability of the particles. For the development of new microscopic polymer acrylated palm oil can be synthesized into nano sized particle and it has potential to be developed in medical devices and controlled-drug-release-applications. (author)

  3. Microemulsions as model fluids for enhanced oil recovery: dynamics adjacent to planar hydrophilic walls

    Directory of Open Access Journals (Sweden)

    Mattauch S.

    2012-10-01

    Full Text Available After the dynamics of microemulsions adjacent to a planar hydrophilic wall have been characterized using grazing incidence neutron spin echo spectroscopy, the model of Seifert was employed to explain the discovered acceleration for the surface near lamellar ordered membranes. Reflections of hydrodynamic waves by the wall – or the volume conservation between the membrane and the wall – explain faster relaxations and, therefore, a lubrication effect that is important for flow fields in narrow pores. The whole scenery is now spectated by using different scenarios of a bicontinuous microemulsion exposed to clay particles and of a lamellar microemulsion adjacent to a planar wall. The Seifert concept could successfully be transferred to the new problems.

  4. Synthesis and characterization of superparamagnetic nanoparticles obtained by precipitation in inverse microemulsion for biomedical applications

    International Nuclear Information System (INIS)

    Puca Pacheco, Mercedes; Guerrero Aquino, Marco; Tacuri Calanchi, Enrique; Lopez Campos, Raul G.

    2013-01-01

    In this work the preparation of nanoparticles of magnetite by methods of precipitation in inverse microemulsions and the conventional method 'Chemical Co-precipitation' is reported. Magnetite nanoparticles were characterized by X-ray diffraction, Moessbauer spectroscopy and vibrating sample magnetometer (VSM). The results showed that the nanoparticles obtained by the method of precipitation in inverse microemulsion showed a superparamagnetic behavior and had a particle average diameter of 9 nm, while by the conventional method 'Chemical Co-precipitation' were 17 nm. In addition, other benefits observed in the application of the method of precipitation in inverse microemulsion with regard to the conventional method is that it allowed obtaining spheroidal magnetite nanoparticles, monodisperse and with magnetic and chemical properties which might have better results in medical applications. (author)

  5. Preparation of nanoparticles from acrylated palm oil microemulsion using radiation technique

    International Nuclear Information System (INIS)

    Rida Tajau; Wan Mohd Zin Wan Yunus; Khairul Zaman Mohd Dahlan; Mohd Hilmi Mahmood; Kamaruddin Hashim; Mohd Yusof Hamzah

    2011-01-01

    The use of microemulsion in the development of nanoparticle based on acrylated palm oil product is demonstrated. Acrylated palm oil microemulsions were prepared using ionic surfactant. Combination methods of emulsion polymerization and radiation crosslinking were applied to the microemulsion system for synthesizing nanoparticle. The ionizing radiation technique was introduced to generate a crosslinking reaction in the development of nanoparticle. The nanoparticle was evaluated in terms of particle diameter, surface charge, pH and conductance. Their image was captured using Transmission electron microscopy (TEM). Results show that the size, charge and shape of the particles are influenced by concentration of surfactants, monomer concentration, radiation dose and time of storage. The study showed a promising method to produced nanoparticle. This nano-sized product has the potential to be utilized as controlled-drug-release-carrier. (Author)

  6. Microemulsion and Sol-Gel Synthesized ZrO2-MgO Catalysts for the Liquid-Phase Dehydration of Xylose to Furfural

    Directory of Open Access Journals (Sweden)

    Almudena Parejas

    2017-12-01

    Full Text Available Two series of catalysts were prepared by sol-gel and microemulsion synthetic procedure (SG and ME, respectively. Each series includes both pure Mg and Zr solids as well as Mg-Zr mixed solids with 25%, 50% and 75% nominal Zr content. The whole set of catalysts was characterized from thermal, structural and surface chemical points of view and subsequently applied to the liquid-phase xylose dehydration to furfural. Reactions were carried out in either a high-pressure autoclave or in an atmospheric pressure multi-reactor under a biphasic (organic/water reaction mixture. Butan-2-ol and toluene were essayed as organic solvents. Catalysts prepared by microemulsion retained part of the surfactant used in the synthetic procedure, mainly associated with the Zr part of the solid. The MgZr-SG solid presented the highest surface acidity while the Mg3Zr-SG one exhibited the highest surface basicity among mixed systems. Xylose dehydration in the high-pressure system and with toluene/water solvent mixture led to the highest furfural yield. Moreover, the yield of furfural increases with the Zr content of the catalyst. Therefore, the catalysts constituted of pure ZrO2 (especially Zr-SG are the most suitable to carry out the process under study although MgZr mixed solids could be also suitable for overall processes with additional reaction steps.

  7. Microemulsion and Sol-Gel Synthesized ZrO₂-MgO Catalysts for the Liquid-Phase Dehydration of Xylose to Furfural.

    Science.gov (United States)

    Parejas, Almudena; Montes, Vicente; Hidalgo-Carrillo, Jesús; Sánchez-López, Elena; Marinas, Alberto; Urbano, Francisco J

    2017-12-18

    Two series of catalysts were prepared by sol-gel and microemulsion synthetic procedure (SG and ME, respectively). Each series includes both pure Mg and Zr solids as well as Mg-Zr mixed solids with 25%, 50% and 75% nominal Zr content. The whole set of catalysts was characterized from thermal, structural and surface chemical points of view and subsequently applied to the liquid-phase xylose dehydration to furfural. Reactions were carried out in either a high-pressure autoclave or in an atmospheric pressure multi-reactor under a biphasic (organic/water) reaction mixture. Butan-2-ol and toluene were essayed as organic solvents. Catalysts prepared by microemulsion retained part of the surfactant used in the synthetic procedure, mainly associated with the Zr part of the solid. The MgZr-SG solid presented the highest surface acidity while the Mg3Zr-SG one exhibited the highest surface basicity among mixed systems. Xylose dehydration in the high-pressure system and with toluene/water solvent mixture led to the highest furfural yield. Moreover, the yield of furfural increases with the Zr content of the catalyst. Therefore, the catalysts constituted of pure ZrO₂ (especially Zr-SG) are the most suitable to carry out the process under study although MgZr mixed solids could be also suitable for overall processes with additional reaction steps.

  8. Microemulsions and Aggregation Formation in Extraction Processes for Used Nuclear Fuel: Thermodynamic and Structural Studies

    Energy Technology Data Exchange (ETDEWEB)

    Nilsson, Mikael [Univ. of California, Irvine, CA (United States)

    2016-05-04

    Advanced nuclear fuel cycles rely on successful chemical separation of various elements in the used fuel. Numerous solvent extraction (SX) processes have been developed for the recovery and purification of metal ions from this used material. However, the predictability of process operations has been challenged by the lack of a fundamental understanding of the chemical interactions in several of these separation systems. For example, gaps in the thermodynamic description of the mechanism and the complexes formed will make predictions very challenging. Recent studies of certain extraction systems under development and a number of more established SX processes have suggested that aggregate formation in the organic phase results in a transformation of its selectivity and efficiency. Aggregation phenomena have consistently been interfering in SX process development, and have, over the years, become synonymous with an undesirable effect that must be prevented. This multiyear, multicollaborative research effort was carried out to study solvation and self-organization in non-aqueous solutions at conditions promoting aggregation phenomena. Our approach to this challenging topic was to investigate extraction systems comprising more than one extraction reagent where synergy of the metal ion could be observed. These systems were probed for the existence of stable microemulsions in the organic phase, and a number of high-end characterization tools were employed to elucidate the role of the aggregates in metal ion extraction. The ultimate goal was to find connections between synergy of metal ion extraction and reverse micellar formation. Our main accomplishment for this project was the expansion of the understanding of metal ion complexation in the extraction system combining tributyl phosphate (TBP) and dibutyl phosphoric acid (HDBP). We have found that for this system no direct correlation exists for the metal ion extraction and the formation of aggregates, meaning that the

  9. Microneedle-Assisted Percutaneous Delivery of a Tetramethylpyrazine-Loaded Microemulsion

    Directory of Open Access Journals (Sweden)

    Qiang Zu

    2017-11-01

    Full Text Available This study examined the efficacy of the percutaneous delivery of a tetramethylpyrazine-loaded microemulsion (TMP-ME on skin pretreated with microneedles (MN. The TMP-ME formulation was optimized in vitro with skin permeation experiments, using a uniform experimental design, guided by a pseudo-ternary phase diagram, in which the TMP skin permeation level and mean particle size were indices. The effects of MN pretreatment on skin permeation by TMP-ME were assessed using in vitro skin permeation, in vivo skin microdialysis, and pharmacokinetic studies in rats. The influence of MN pretreatment on the skin barrier function was evaluated by measuring the electrical resistance of rat skin before and after MN insertion. In the optimal formulation of TMP-ME, the weight percentages of Maisine® 35-1 (oil phase, Labrasol® (surfactant, and Transcutol® P (co-surfactant were 7%, 30% and 10%, respectively, with 1.5% TMP loading. In the in vitro skin permeation study, MN-assisted TMP-ME exhibited a two-fold increase in a 24-h cumulative TMP permeation compared with TMP-ME alone (p < 0.05. In the skin microdialysis study, TMP in MN-assisted TMP-ME exhibited a 1.25-fold increase in Cmax, a 0.93-fold decrease in Tmax, and a 0.88-fold increase in AUC0–t (p < 0.05. Similarly, in the pharmacokinetic study, TMP in MN-assisted TMP-ME exhibited a 2.11-fold increase in Cmax, a 0.67-fold decrease in Tmax, and a 1.07-fold increase in AUC0–t (p < 0.05. The percutaneous electrical resistance of rat skin before and after MN insertion was 850 ± 50 Ω/cm2 and 283 ± 104 Ω/cm2 respectively, indicating that MN dramatically compromises the skin barrier. These results suggest that MN assistance increases the skin permeation rate and the extent of percutaneous absorption of TMP-ME, and that the mechanism may involve the reversible barrier perturbation effect. The rate and extent of percutaneous absorption of TMP-ME can be significantly enhanced by MN assistance, possibly

  10. Microemulsions and Aggregation Formation in Extraction Processes for Used Nuclear Fuel: Thermodynamic and Structural Studies

    International Nuclear Information System (INIS)

    Nilsson, Mikael

    2016-01-01

    Advanced nuclear fuel cycles rely on successful chemical separation of various elements in the used fuel. Numerous solvent extraction (SX) processes have been developed for the recovery and purification of metal ions from this used material. However, the predictability of process operations has been challenged by the lack of a fundamental understanding of the chemical interactions in several of these separation systems. For example, gaps in the thermodynamic description of the mechanism and the complexes formed will make predictions very challenging. Recent studies of certain extraction systems under development and a number of more established SX processes have suggested that aggregate formation in the organic phase results in a transformation of its selectivity and efficiency. Aggregation phenomena have consistently been interfering in SX process development, and have, over the years, become synonymous with an undesirable effect that must be prevented. This multiyear, multicollaborative research effort was carried out to study solvation and self-organization in non-aqueous solutions at conditions promoting aggregation phenomena. Our approach to this challenging topic was to investigate extraction systems comprising more than one extraction reagent where synergy of the metal ion could be observed. These systems were probed for the existence of stable microemulsions in the organic phase, and a number of high-end characterization tools were employed to elucidate the role of the aggregates in metal ion extraction. The ultimate goal was to find connections between synergy of metal ion extraction and reverse micellar formation. Our main accomplishment for this project was the expansion of the understanding of metal ion complexation in the extraction system combining tributyl phosphate (TBP) and dibutyl phosphoric acid (HDBP). We have found that for this system no direct correlation exists for the metal ion extraction and the formation of aggregates, meaning that the

  11. Microneedle-Assisted Percutaneous Delivery of a Tetramethylpyrazine-Loaded Microemulsion.

    Science.gov (United States)

    Zu, Qiang; Yu, Yanyan; Bi, Xiaolin; Zhang, Ren; Di, Liuqing

    2017-11-21

    This study examined the efficacy of the percutaneous delivery of a tetramethylpyrazine-loaded microemulsion (TMP-ME) on skin pretreated with microneedles (MN). The TMP-ME formulation was optimized in vitro with skin permeation experiments, using a uniform experimental design, guided by a pseudo-ternary phase diagram, in which the TMP skin permeation level and mean particle size were indices. The effects of MN pretreatment on skin permeation by TMP-ME were assessed using in vitro skin permeation, in vivo skin microdialysis, and pharmacokinetic studies in rats. The influence of MN pretreatment on the skin barrier function was evaluated by measuring the electrical resistance of rat skin before and after MN insertion. In the optimal formulation of TMP-ME, the weight percentages of Maisine ® 35-1 (oil phase), Labrasol ® (surfactant), and Transcutol ® P (co-surfactant) were 7%, 30% and 10%, respectively, with 1.5% TMP loading. In the in vitro skin permeation study, MN-assisted TMP-ME exhibited a two-fold increase in a 24-h cumulative TMP permeation compared with TMP-ME alone ( p < 0.05). In the skin microdialysis study, TMP in MN-assisted TMP-ME exhibited a 1.25-fold increase in C max , a 0.93-fold decrease in T max , and a 0.88-fold increase in AUC 0-t ( p < 0.05). Similarly, in the pharmacokinetic study, TMP in MN-assisted TMP-ME exhibited a 2.11-fold increase in C max , a 0.67-fold decrease in T max , and a 1.07-fold increase in AUC 0-t ( p < 0.05). The percutaneous electrical resistance of rat skin before and after MN insertion was 850 ± 50 Ω/cm² and 283 ± 104 Ω/cm² respectively, indicating that MN dramatically compromises the skin barrier. These results suggest that MN assistance increases the skin permeation rate and the extent of percutaneous absorption of TMP-ME, and that the mechanism may involve the reversible barrier perturbation effect. The rate and extent of percutaneous absorption of TMP-ME can be significantly enhanced by MN assistance, possibly

  12. Flow of gasoline-in-water microemulsion through water-saturated soil columns

    International Nuclear Information System (INIS)

    Ouyang, Y.; Mansell, R.S.; Rhue, R.D.

    1995-01-01

    Much consideration has been given to the use of surfactants to clean up nonaqueous phase liquids (NAPLs) from contaminated soil and ground water. Although this emulsification technique has shown significant potential for application in environmental remediation practices, a major obstacle leading to low washing efficiency is the potential formation of macroemulsion with unfavorable flow characteristics in porous media. This study investigated influences of the flow of leaded-gasoline-in-water (LG/W) microemulsion upon the transport of gasoline and lead (Pb) species in water-saturated soil columns. Two experiments were performed: (1) the immiscible displacement of leaded gasoline and (2) the miscible displacement of LG/W microemulsion through soil columns, followed by sequentially flushing with NaCl solution and a water/surfactant/cosurfactant (W/S/CoS) mixture. Comparison of breakthrough curves (BTC) for gasoline between the two experiments shows that about 90% of gasoline and total Pb were removed from the soil columns by NaCl solution in the LG/W microemulsion experiment as compared to 40% removal of gasoline and 10% removal of total Pb at the same process in the leaded gasoline experiment. Results indicate that gasoline and Pb species moved much more effectively through soil during miscible flow of LG/W microemulsion than during immiscible flow of leaded gasoline. In contrast to the adverse effects of macroemulsion on the transport of NAPLs, microemulsion was found to enhance the transport of gasoline through water-saturated soil. Mass balance analysis shows that the W/S/CoS mixture had a high capacity for removing residual gasoline and Pb species from contaminated soil. Comparison of water-pressure differences across the soil columns for the two experiments indicates that pore clogging by gasoline droplets was greatly minimized in the LG/W microemulsion experiment

  13. Two-chiral component microemulsion EKC - chiral surfactant and chiral oil. Part 2: diethyl tartrate.

    Science.gov (United States)

    Kahle, Kimberly A; Foley, Joe P

    2007-08-01

    In this second study on dual-chirality microemulsions containing a chiral surfactant and a chiral oil, a less hydrophobic and lower interfacial tension chiral oil, diethyl tartrate, is employed (Part 1, Foley, J. P. et al.., Electrophoresis, DOI: 10.1002/elps.200600551). Six stereochemical combinations of dodecoxycarbonylvaline (DDCV: R, S, or racemic, 2.00% w/v), racemic 2-hexanol (1.65% v/v), and diethyl tartrate (D, L, or racemic, 0.88% v/v) were examined as pseudostationary phases (PSPs) for the enantioseparation of six chiral pharmaceutical compounds: pseudoephedrine, ephedrine, N-methyl ephedrine, metoprolol, synephrine, and atenolol. Average efficiencies increased with the addition of a chiral oil to R-DDCV PSP formulations. Modest improvements in resolution and enantioselectivity (alpha(enant)) were achieved with two-chiral-component systems over the one-chiral-component microemulsion. Slight enantioselective synergies were confirmed using a thermodynamic model. Results obtained in this study are compared to those obtained in Part 1 as well as those obtained with chiral MEEKC using an achiral, low-interfacial-tension oil (ethyl acetate). Dual-chirality microemulsions with the more hydrophobic oil dibutyl tartrate yielded, relative to diethyl tartrate, higher efficiencies (100,000-134,000 vs. 80,800-94,300), but lower resolution (1.64-1.91 vs. 2.08-2.21) due to lower enantioselectivities (1.060-1.067 vs. 1.078-1.081). Atenolol enantiomers could not be separated with the dibutyl tartrate-based microemulsions but were partially resolved using diethyl tartrate microemulsions. A comparable single-chirality microemulsion based on the achiral oil ethyl acetate yielded, relative to diethyl tartrate, lower efficiency (78 300 vs. 91 600), higher resolution (1.99 vs. 1.83), and similar enantioselectivities.

  14. XPS analysis of supported catalysts prepared in water-in-oil microemulsion system

    International Nuclear Information System (INIS)

    Mohd Ambar Yarmo; Wong Hoi Jin; Tan Chew Khim; Anita Ramli; Shahidan Radiman

    2002-01-01

    Catalysts supported on γ-alumina prepared by water-in-oil microemulsion were studied by X-ray photoelectron spectroscopy for comparison with catalysts prepared by wet impregnation. Comparable shifts to higher binding energies indicated a metal-support interaction where metal obtained via microemulsion is very small in size and highly dispersed. The positive binding energy shifts could be explained from a net unit positive charge remaining on the cluster in the photoemission final state in addition to the metallic screening from a redistribution of states within the bands. (Author)

  15. High monomer content batch microemulsion polymerization of butyl acrylate initiated with gamma ray

    Energy Technology Data Exchange (ETDEWEB)

    Chen Jun [Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026 (China)]. E-mail: chjun04@mail.ustc.edu.cn; Zhang Zhicheng [Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026 (China)]. E-mail: zczhang@ustc.edu.cn

    2007-05-15

    Radiation polymerization of butyl acrylate was performed in a microemulsion stabilized with a mixture of sodium of 12-acryloxy-9-octadecenoic acid and sodium dodecyl sulfate in a weight ratio of 2 at room temperature. BA content in microemulsion can be successfully improved up to 40 wt% with low surfactant concentration (lower than 10 wt%). The resulted stable, translucent microlatex contain particles with average diameter from 28.1 to 38.1 nm with different monomer content. Particle size depends on the dose rate and surfactant concentration. Effects of monomer content and dose rate on the maximum polymerization rate are discussed.

  16. Preparation, characterization and relative bioavailability of oral elemene o/w microemulsion

    Directory of Open Access Journals (Sweden)

    Zhaowu Zeng

    2010-08-01

    Full Text Available Zhaowu Zeng1, Guanglin Zhou1, Xiaoli Wang2, Eric Zhijian Huang1, Xiaori Zhan1, Jun Liu1, Shuling Wang1, Anming Wang1, Haifeng Li1, Xiaolin Pei1, Tian Xie11Research Center for Biomedicine and Health, Hangzhou Normal University, Hangzhou, Zhejiang, China; 2Yichun University of Jiangxi Province, Yichun, Jiangxi, ChinaAbstract: The objective was to develop an elemene oil/water (o/w microemulsion and evaluate its characteristics and oral relative bioavailability in rats. Elemene was used as the oil phase and drug, polysorbate 80 as a surfactant along with ethanol, propylene glycol, and glycerol as the cosurfactants. The microemulsion was prepared by mixing method, or ultrasonication method in an ultrasonic bath. Its three-dimensional response surface diagram was drawn by Mathcad software. The microemulsion was characterized by visual observation, cross-polarized microscopy, size, zeta potential, acidity, viscosity, and surface tension measurement. The drug content and entrapment efficiency were determined by ultra fast liquid chromatography (UFLC and liquid surface method. Blood was drawn from rats at different time points after oral administration of an elemene microemulsion or a commercial elemene emulsion for measurement of the drug in plasma by UFLC to establish the pharmacokinetic parameters and relative bioavailability. The elemene microemulsion as a clarified and isotropic system containing 1% elemene (w/v, 5% ethanol (v/v, 15% propylene glycol (v/v, 15% glycerol (v/v, and 5% polysorbate 80 (w/v, was characterized as (57.7 ± 2.8 nm in size, 0.485 ± 0.032 in polydispersity index, (3.2 ± 0.4 mv in zeta potential, (5.19 ± 0.08 in pH, 6 mpa•s in viscosity, (31.8 ± 0.3 mN•m-1 in surface tension, (8.273 ± 0.018 mg•mL-1 in content of ß-elemene, and (99.81 ± 0.24% in average entrapment efficiency. The area under the concentration-time curves from 0 h to 24 h (AUC0→24h of the elemene microemulsion and commercial elemene emulsion were

  17. Radiation Induced Formation of Acrylated Palm Oil Nanoparticles using Cetyltrimethylammonium Bromide Microemulsion System

    International Nuclear Information System (INIS)

    Rida Tajau; Rida Tajau; Wan Mohd Zin Wan Yunus

    2011-01-01

    In this study, we report the preparation of Acrylated Palm Oil (APO) nanoparticles using aqueous Cetyltrimethylammonium bromide (CTAB) microemulsion system. This microemulsion system which contains the dispersed APO nano droplets was subjected to the gamma irradiation to induce the formation of the crosslinked APO nanoparticle. After irradiation at higher doses, the size of APO nanoparticles was transformed from a submicron-sized to a nano-sized of the particles. Size decreasing might be due to the intermolecular and the intramolecular crosslinking reactions of the APO nanoparticles during the irradiation process. (author)

  18. Growth of polymer nanoparticles in microemulsion polymerization initiated with γ ray

    International Nuclear Information System (INIS)

    Xu Xiangling; Ge Xuewu; Ye Qiang; Zhang Zhicheng; Zuo Ju; Niu Aizhen; Zhang Manwei

    1999-01-01

    In microemulsion polymerization of styrene, butyl acrylate and methyl methacrylate initiated with gamma ray, growth of polymer nanoparticles was observed with photon correlation spectroscopy, and the conversion curve was recorded with a dilatometer. There is some similarity in the growth of polymer particles. The size of polymer particles rapidly increases up to their maximum at the early stage. With the increase of conversion, the large particles supply their monomer to newly formed particles and become smaller. In all these three microemulsion polymerizations, the evidence of continuous nucleation was observed. When monomer is styrene or butyl acrylate, a plateau of polymerization rate emerges. When monomer is methyl methacrylate, no plateau of polymerization is observed

  19. Novel Montmorillonite/TiO2/MnAl-Mixed Oxide Composites Prepared from Inverse Microemulsions as Combustion Catalysts

    Directory of Open Access Journals (Sweden)

    Bogna D. Napruszewska

    2017-11-01

    Full Text Available A novel design of combustion catalysts is proposed, in which clay/TiO2/MnAl-mixed oxide composites are formed by intermixing exfoliated organo-montmorillonite with oxide precursors (hydrotalcite-like in the case of Mn-Al oxide obtained by an inverse microemulsion method. In order to assess the catalysts’ thermal stability, two calcination temperatures were employed: 450 and 600 °C. The composites were characterized with XRF (X-ray fluorescence, XRD (X-ray diffraction, HR SEM (high resolution scanning electron microscopy, N2 adsorption/desorption at −196 °C, and H2 TPR (temperature programmed reduction. Profound differences in structural, textural and redox properties of the materials were observed, depending on the presence of the TiO2 component, the type of neutralization agent used in the titania nanoparticles preparation (NaOH or NH3 (aq, and the temperature of calcination. Catalytic tests of toluene combustion revealed that the clay/TiO2/MnAl-mixed oxide composites prepared with the use of ammonia showed excellent activity, the composites obtained from MnAl hydrotalcite nanoparticles trapped between the organoclay layers were less active, but displayed spectacular thermal stability, while the clay/TiO2/MnAl-mixed oxide materials obtained with the aid of NaOH were least active. The observed patterns of catalytic activity bear a direct relation to the materials’ composition and their structural, textural, and redox properties.

  20. Novel Montmorillonite/TiO₂/MnAl-Mixed Oxide Composites Prepared from Inverse Microemulsions as Combustion Catalysts.

    Science.gov (United States)

    Napruszewska, Bogna D; Michalik-Zym, Alicja; Rogowska, Melania; Bielańska, Elżbieta; Rojek, Wojciech; Gaweł, Adam; Wójcik-Bania, Monika; Bahranowski, Krzysztof; Serwicka, Ewa M

    2017-11-19

    A novel design of combustion catalysts is proposed, in which clay/TiO₂/MnAl-mixed oxide composites are formed by intermixing exfoliated organo-montmorillonite with oxide precursors (hydrotalcite-like in the case of Mn-Al oxide) obtained by an inverse microemulsion method. In order to assess the catalysts' thermal stability, two calcination temperatures were employed: 450 and 600 °C. The composites were characterized with XRF (X-ray fluorescence), XRD (X-ray diffraction), HR SEM (high resolution scanning electron microscopy, N₂ adsorption/desorption at -196 °C, and H₂ TPR (temperature programmed reduction). Profound differences in structural, textural and redox properties of the materials were observed, depending on the presence of the TiO₂ component, the type of neutralization agent used in the titania nanoparticles preparation (NaOH or NH₃ (aq)), and the temperature of calcination. Catalytic tests of toluene combustion revealed that the clay/TiO₂/MnAl-mixed oxide composites prepared with the use of ammonia showed excellent activity, the composites obtained from MnAl hydrotalcite nanoparticles trapped between the organoclay layers were less active, but displayed spectacular thermal stability, while the clay/TiO₂/MnAl-mixed oxide materials obtained with the aid of NaOH were least active. The observed patterns of catalytic activity bear a direct relation to the materials' composition and their structural, textural, and redox properties.

  1. Lecithin-based microemulsion of a peptide for oral administration: preparation, characterization, and physical stability of the formulation.

    Science.gov (United States)

    Cilek, Ayşe; Celebi, Nevin; Tirnaksiz, Figen

    2006-01-01

    The objective of our study was to prepare and characterize a stable microemulsion formulation for oral administration of a peptide, e.g., rh-insulin. The microemulsions were prepared using Labrafil M 1944 CS, Phospholipon 90G (lecithin), absolute alcohol, and bidistilled water. Commercially available soybean lecithins (namely, Phospholipon 80, phosphatidylcholine purity 76 +/- 3%, and Phospholipon 90G, phosphatidylcholine purity 93 +/- 3%) were used in the study. The results showed that the phase diagram obtained using a low purity lecithin was not similar to that obtained with a high purity lecithin. We observed that the microemulsion area was wider at the phase diagram obtained with the higher purity lecithin. We found that the extent of the microemulsion region depended upon both the purity of the lecithin and the surfactant/co-surfactant (s/co-s) mixing ratios (K(m)). The rheological studies showed that microemulsions followed a Newtonian behavior. Such physical characteristics as viscosity, turbidity, density, conductivity, refractive index, droplet size, physical appearance, and phase separation of the microemulsion were measured at different temperatures (4 degrees C, 25 degrees C, and 40 degrees C) during 6 months. The results indicated that the physical characteristics of the developed microemulsions did not change under different storage temperatures (p > 0.05).

  2. Intravenous microemulsion of docetaxel containing an anti-tumor synergistic ingredient (Brucea javanica oil): formulation and pharmacokinetics.

    Science.gov (United States)

    Ma, Shilin; Chen, Fen; Ye, Xiaohui; Dong, Yingjie; Xue, Yingna; Xu, Heming; Zhang, Wenji; Song, Shuangshuang; Ai, Li; Zhang, Naixian; Pan, Weisan

    2013-01-01

    The purpose of this study was to develop a docetaxel microemulsion containing an anti-tumor synergistic ingredient (Brucea javanica oil) and to investigate the characteristics of the microemulsion. Brucea javanica oil contains oleic acid and linoleic acids that have been shown by animal and human studies to inhibit tumor formation. The microemulsion containing Brucea javanica oil, medium-chain triglyceride, soybean lecithin, Solutol®HS 15, PEG 400, and water was developed for docetaxel intravenous administration. A formulation with higher drug content, lower viscosity, and smaller particle size was developed. The droplet size distribution of the dispersed phase of the optimized microemulsion was 13.5 nm, determined using a dynamic light scattering technique. The small droplet size enabled the microemulsion droplets to escape from uptake and phagocytosis by the reticuloendothelial system and increased the circulation time of the drug. The zeta potential was -41.3 mV. The optimized microemulsion was pale yellow, transparent, and non-opalescent in appearance. The value of the combination index was 0.58, showing that there was a synergistic effect when docetaxel was combined with Brucea javanica oil. After a single intravenous infusion dose (10 mg/kg) in male Sprague Dawley rats, the area under the curve of the microemulsion was higher and the half-time was longer compared with that of docetaxel solution alone, and showed superior pharmacokinetic characteristics. These results indicate that this preparation of docetaxel in emulsion is likely to provide an excellent prospect for clinical tumor treatment.

  3. Properties of surfactant films in water-in-CO2 microemulsions obtained by small-angle neutron scattering.

    Science.gov (United States)

    Yan, Ci; Sagisaka, Masanobu; James, Craig; Rogers, Sarah; Alexander, Shirin; Eastoe, Julian

    2014-12-01

    The formation, stability and structural properties of normal liquid phase microemulsions, stabilized by hydrocarbon surfactants, comprising water and hydrocarbon oils can be interpreted in terms of the film bending rigidity (energy) model. Here, this model is tested for unusual water-in-CO2 (w/c) microemulsions, formed at high pressure with supercritical CO2 (sc-CO2) as a solvent and fluorinated surfactants as stabilizers. Hence, it is possible to explore the generality of this model for other types of microemulsions. High Pressure Small-Angle Neutron Scattering (HP-SANS) has been used to study w/c microemulsions, using contrast variation to highlight scattering from the stabilizing fluorinated surfactant films: these data show clear evidence for spherical core-shell structures for the microemulsion droplets. The results extend understanding of w/c microemulsions since previous SANS studies are based only on scattering from water core droplets. Here, detailed structural parameters for the surfactant films, such as thickness and film bending energy, have been extracted from the core-shell SANS profiles revealed by controlled contrast variation. Furthermore, at reduced CO2 densities (∼0.7gcm(-3)), elongated cylindrical droplet structures have been observed, which are uncommon for CO2 microemulsions/emulsions. The implications of the presence of cylindrical micelles and droplets for applications of CO2, and viscosity enhancements are discussed. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. In vitro and in vivo evaluation of a water-in-oil microemulsion system for enhanced peptide intestinal delivery.

    Science.gov (United States)

    Liu, Dongyun; Kobayashi, Taku; Russo, Steven; Li, Fengling; Plevy, Scott E; Gambling, Todd M; Carson, Johnny L; Mumper, Russell J

    2013-01-01

    Peptide and protein drugs have become the new generation of therapeutics, yet most of them are only available as injections, and reports on oral local intestinal delivery of peptides and proteins are quite limited. The aim of this work was to develop and evaluate a water-in-oil (w/o) microemulsion system in vitro and in vivo for local intestinal delivery of water-soluble peptides after oral administration. A fluorescent labeled peptide, 5-(and-6)-carboxytetramethylrhodamine labeled HIV transactivator protein TAT (TAMRA-TAT), was used as a model peptide. Water-in-oil microemulsions consisting of Miglyol 812, Capmul MCM, Tween 80, and water were developed and characterized in terms of appearance, viscosity, conductivity, morphology, and particle size analysis. TAMRA-TAT was loaded and its enzymatic stability was assessed in modified simulated intestinal fluid (MSIF) in vitro. In in vivo studies, TAMRA-TAT intestinal distribution was evaluated using fluorescence microscopy after TAMRA-TAT microemulsion, TAMRA-TAT solution, and placebo microemulsion were orally gavaged to mice. The half-life of TAMRA-TAT in microemulsion was enhanced nearly three-fold compared to that in the water solution when challenged by MSIF. The treatment with TAMRA-TAT microemulsion after oral administration resulted in greater fluorescence intensity in all intestine sections (duodenum, jejunum, ileum, and colon) compared to TAMRA-TAT solution or placebo microemulsion. The in vitro and in vivo studies together suggested TAMRA-TAT was better protected in the w/o microemulsion in an enzyme-containing environment, suggesting that the w/o microemulsions developed in this study may serve as a potential delivery vehicle for local intestinal delivery of peptides or proteins after oral administration.

  5. Preparation methods for monodispersed garlic oil microspheres in water using the microemulsion technique and their potential as antimicrobials.

    Science.gov (United States)

    Zheng, Hua Ming; Li, Hou Bin; Wang, Da Wei; Liu, Dun

    2013-08-01

    Garlic oil is considered as a natural broad-spectrum antibiotic because of its well-known antimicrobial activity. However, the characteristics of easy volatility and poor aqueous solubility limit the application of garlic oil in industry. The purpose of the present work is to develop and evaluate an oil-free microemulsion by loading garlic oil in microemulsion system. Microemulsions were prepared with ethoxylated hydrogenated castor (Cremophor RH40) as surfactant, n-butanol (or ethanol) as cosurfactant, oleic acid-containing garlic oil as oil phase, and ultrapure water as water phase. The effects of the ratio of surfactant to cosurfactant and different oil concentration on the area of oil-in-water (O/W) microemulsion region in pseudoternary phase diagrams were investigated. The particle size and garlic oil encapsulation efficiency of the formed microemulsions with different formulations were also investigated. In addition, the antimicrobial activity in vitro against Escherichia coli and Staphylococcus aureus was assessed. The experimental results show that a stable microemulsion region can be obtained when the mass ratio of surfactant to cosurfactant is, respectively, 1:1, 2:1, and 3:1. Especially, when the mixture surfactants of RH40/n-butanol 2/1 (w/w) is used in the microemulsion formulation, the area of O/W microemulsion region is 0.089 with the particle size 13.29 to 13.85 nm and garlic oil encapsulation efficiency 99.5%. The prepared microemulsion solution exhibits remarkable antibacterial activity against S. aureus. © 2013 Institute of Food Technologists®

  6. The effect of water on the microstructure of 1-butyl-3-methylimidazolium tetrafluoroborate/TX-100/benzene ionic liquid microemulsions.

    Science.gov (United States)

    Gao, Yan'an; Li, Na; Zheng, Liqiang; Zhao, Xueyan; Zhang, Jin; Cao, Quan; Zhao, Mingwei; Li, Zhen; Zhang, Gaoyong

    2007-01-01

    The ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) forms nonaqueous microemulsions with benzene with the aid of nonionic surfactant TX-100. The phase diagram of the ternary system was prepared, and the microstructures of the microemulsion were recognized. On the basis of the phase diagram, a series of ionic liquid-in-oil (IL/O) microemulsions were chosen and characterized by dynamic light scattering (DLS), which shows a similar swelling behavior to typical water-in-oil (W/O) microemulsions. The existence of IL pools in the IL/O microemulsion was confirmed by UV/Vis spectroscopic analysis with CoCl2 and methylene blue (MB) as the absorption probes. A constant polarity of the IL pool is observed, even if small amounts of water are added to the microemulsion, thus suggesting that the water molecules are solubilized in the polar outer shell of the microemulsion, as confirmed by FTIR spectra. 1H NMR spectroscopic analysis shows that these water molecules interact with the electronegative oxygen atoms of the oxyethylene (OE) units of TX-100 through hydrogen-bonding interactions, and the electronegative oxygen atoms of the water molecules attract the electropositive imidazolium rings of [bmim][BF4]. Hence, the water molecules are like a glue that stick the IL and OE units more tightly together and thus make the microemulsion system more stable. Considering the unique solubilization behavior of added water molecules, the IL/O microemulsion system may be used as a medium to prepare porous or hollow nanomaterials by hydrolysis reactions.

  7. Controlled synthesis of size-tunable nickel and nickel oxide nanoparticles using water-in-oil microemulsions

    International Nuclear Information System (INIS)

    Kumar, Ajeet; Saxena, Amit; Shankar, Ravi; Mozumdar, Subho; De, Arnab

    2013-01-01

    Industrial demands have generated a growing need to synthesize pure metal and metal–oxide nanoparticles of a desired size. We report a novel and convenient method for the synthesis of spherical, size tunable, well dispersed, stable nickel and nickel oxide nanoparticles by reduction of nickel nitrate at room temperature in a TX-100/n-hexanol/cyclohexane/water system by a reverse microemulsion route. We determined that reduction with alkaline sodium borohydrate in nitrogen atmosphere leads to the formation of nickel nanoparticles, while the use of hydrazine hydrate in aerobic conditions leads to the formation of nickel oxide nanoparticles. The influence of several reaction parameters on the size of nickel and nickel oxide nanoparticles were evaluated in detail. It was found that the size can be easily controlled either by changing the molar ratio of water to surfactant or by simply altering the concentration of the reducing agent. The morphology and structure of the nanoparticles were characterized by quasi-elastic light scattering (QELS), transmission electron microscopy (TEM), x-ray diffraction (XRD), electron diffraction analysis (EDA) and energy dispersive x-ray (EDX) spectroscopy. The results show that synthesized nanoparticles are of high purity and have an average size distribution of 5–100 nm. The nanoparticles prepared by our simple methodology have been successfully used for catalyzing various chemical reactions. (paper)

  8. Quantification of the level of fat-soluble vitamins in feed based on the novel microemulsion electrokinetic chromatography (MEEKC) method.

    Science.gov (United States)

    Olędzka, Ilona; Kowalski, Piotr; Bałuch, Alicja; Bączek, Tomasz; Paradziej-Łukowicz, Jolanta; Taciak, Marcin; Pastuszewska, Barbara

    2014-02-01

    Simultaneous quantification of liposoluble vitamins is not a new area of interest, since these compounds co-determine the nutritional quality of food and feed, a field widely explored in the human and animal diet. However, the development of appropriate methods is still a matter of concern, especially when the vitamin composition is highly complex, as is the case with feed designated for laboratory animals, representing a higher health and microbiological status. A method combining microemulsion electrokinetic chromatography (MEEKC) with liquid-liquid extraction was developed for the determination of four fat-soluble vitamins in animal feed. A separation medium consisting of 25 mmol L⁻¹ phosphate buffer (pH 2.5), 2-propanol, 1-butanol, sodium dodecyl sulfate and octane allowed the simultaneous determination of vitamins A, D, E and K within a reasonable time of 25 min. The polarity of the separation voltage was reversed in view of the strongly suppressed electro-osmotic flow, and the applied voltage was set at 12 kV. The fat-soluble vitamins were separated in the order of decreasing hydrophobicity. It was proved that the proposed MEEKC method was sufficiently specific and sensitive for screening fat-soluble vitamins in animal feed samples after their sterilization. © 2013 Society of Chemical Industry.

  9. [Analysis of phthalate esters in plastic-packaging bags on-line sample stacking-microemulsion electrokinetic chromatography].

    Science.gov (United States)

    Xiao, Jia; Huang, Ying; Wang, Minyi; Chen, Guonan

    2012-09-01

    Two convenient, effective, and reproducible methods using microemulsion electrokinetic chromatography (MEEKC)-normal stacking mode (NSM) and reversed electrode polarity stacking mode (REPSM) were developed for the on-line sample stacking of phthalate esters (PAEs). REPSM coupled with MEEKC increased the sensitivity of 937.5 to 7,143 times for four PAEs compared to the conventional MEEKC. The separating conditions in the MEEKC method were studied, and many factors influencing the two sample stacking processes were investigated in detail. The optimum sample matrices for the two stacking methods were as follows: 30 mmol/L sodium cholate (SC) and 30.0 mmol/L borate (pH 8.5). Additionally, sample injections as large as 3.45 kPa x 40 s and 3.45 kPa x 90 s were applied for NSM-MEEKC and REPSM-MEEKC, respectively. The linear relationship and reproducibility were also examined. Under the optimum conditions, the detection limits (S/N = 3) of the PAEs were in the ranges of 0.021 - 0.33 mg/L and 0.7 - 4 microg/L for NSM-MEEKC and REPSM-MEEKC, respectively. The proposed REPSM-MEEKC has been successfully applied to determine PAEs in plastic-packaging bags, and the spiked recoveries were in the range of 89.1% - 105.6% with satisfactory results.

  10. Synthesis of Zn/Co/Fe-layered double hydroxide nanowires with controllable morphology in a water-in-oil microemulsion

    Energy Technology Data Exchange (ETDEWEB)

    Wu Hongyu; Jiao Qingze [School of Chemical Engineering and Environment, Beijing Institute of Technology, Beijing, 100081 (China); Zhao Yun, E-mail: zhaoyun@bit.edu.cn [School of Chemical Engineering and Environment, Beijing Institute of Technology, Beijing, 100081 (China); Huang Silu; Li Xuefei; Liu Hongbo; Zhou Mingji [School of Chemical Engineering and Environment, Beijing Institute of Technology, Beijing, 100081 (China)

    2010-02-15

    The Zn/Co/Fe-layered double hydroxide nanowires were synthesized via a reverse microemulsion method by using cetyltrimethyl ammonium bromide (CTAB) /n-hexane/n-hexanol/water as Soft-Template. ZnSO{sub 4}, CoSO{sub 4}, Fe{sub 2}(SO{sub 4}){sub 3} and urea were used as raw materials. The influence of reaction temperature, time, urea concentration and Cn (molar ratio of cetyltrimethyl ammonium bromide to water) on the structure and morphology of Zn/Co/Fe-layered double hydroxides was investigated. The samples were characterized using Transmission Electron Microscopy (TEM), Inductively Coupled Plasma (ICP), X-ray Diffraction (XRD) and Infrared Absorption Spectrum (IR). The results indicate that higher temperature is beneficial to the formation of layered double hydroxides, but particles apart from nanowires could be produced if temperature is up to 120 deg. C. By varying the temperature, reaction time, urea concentration and Cn, we got the optimum conditions of synthesizing uniform Zn/Co/Fe-layered double hydroxide nanowires: 100 deg. C, more than 12 h, Cn: 30-33, urea concentration: 0.3 M.

  11. Characterization of nanoparticles of lidocaine in w/o microemulsions ...

    Indian Academy of Sciences (India)

    drophilic phase and a hydrophobic phase, stabilized with the use of surfactants. Regular MEs consist of nanometer-sized hydrocarbon domains (termed micelles) surrounded by amphiphilic molecules, stabilized in a continuous aqueous phase. In contrast, reverse (w/o) MEs consist of aqueous domains (termed reverse ...

  12. Design of a microemulsion-based drug delivery system for diclofenac sodium

    International Nuclear Information System (INIS)

    Kkizibash, N.A.; Asif, S.; Nazar, M.F.; Alenizi, D.; Shah, S.S.

    2011-01-01

    A microemulsion-based drug delivery system has been designed for Diclofenac Sodium(DS) comprising Span 60, 1-Propanol, Water, and Lemon Oil. The microemulsion system has been characterized by a pseudo-ternary phase diagram using the water titration method. The properties and structure of this system have been studied by the use of refractive index, electrical conductivity, viscosity and UV-Visible spectroscopy. The conductivity (s) and viscosity (k nu) measurements have provided evidence for percolation behavior with variation in F (weight fraction of aqueous phase). This phase transition corresponds to the structural change from water-in-oil to a bicontinuous microemulsion system. The percolation threshold (FC) obtained from conductivity measurements was in accordance with that obtained by viscosity measurements. Five microemulsion samples were selected and the changes in microstructure after incorporation of the drug, Diclofenac Sodium (DS) were examined by centrifugation, conductivity measurements, viscosity measurements and spectroscopic studies. The conductivity measurements showed that DS-loaded samples have higher conductivity values when compared to non-loaded samples. It was also found that DS is inter facially active. In addition, loading of DS had no negative effect on the stability of the system. (author)

  13. Static and dynamic scattering from ternary polymer blends: Bicontinuous microemulsions, Lifshitz lines, and amphiphilicity

    Czech Academy of Sciences Publication Activity Database

    Morkved, T. L.; Štěpánek, Petr; Krishnan, K.; Bates, F. S.; Lodge, T. P.

    2001-01-01

    Roč. 114, č. 16 (2001), s. 7247-7259 ISSN 0021-9606 R&D Projects: GA AV ČR IAA1050902; GA AV ČR KSK2050602 Institutional research plan: CEZ:AV0Z4050913 Keywords : Polymer blends * microemulsion * small-angle neutron scattering Subject RIV: BJ - Thermodynamics Impact factor: 3.147, year: 2001

  14. Structure Study on Microemulsion System with an Ionic Liquid (IL) by Small-Angle Neutron Scattering

    Science.gov (United States)

    Kang, Tae Hui; Qian, Shuo; Smith, Gregory S.; Do, Changwoo; Heller, William T.

    The self-assembly of IL with a long alkyl chains provides molecular level control on the structure enabling applications, including, creating microemulsion with dual functions of extractant and surfactant. The IL, C14MIMCl is not soluble in alkane solvents, even with the addition of octanol. However, with a small amount of water, a water-in-oil micromemulsion forms, that obeys the swelling law with water content. The mixed surfactant system, C14MIMCl/octanol, has different chemistry and molecular geometries depending on its composition. Through the use of SANS, it is possible to determine the impact of the surfactant system on the structure of the microemulsion, as well as to learn the composition of various regions in the structure. The microemulsion system was studied by dilution with octane from 10 to 70 wt%. A strong intensity peak was observed near 0.1 Å-1, and the stable phase shows a structural transition at 30 wt% octane. Contrast variation experiments were done with d-octane and h-octane to understand the structure of the microemulsion, as well as the structural transition. Further, systematic concentration studies of surfactant at constant water-to-oil molar ratio and of water at constant 30 wt% surfactant were performed.

  15. Competition between a lamellar and a microemulsion phase in an ionic surfactant system

    NARCIS (Netherlands)

    Kegel, W.K.; Lekkerkerker, H.N.W.

    1993-01-01

    An experimental study of a microemulsion system consisting of equal volumes of brine (water plus salt) and oil (cyclohexane), sodium dodecyl sulfate (SDS) as surfactant, and a mixture of hexanol and pentanol as cosurfactant is presented. Increasing the hexanol fraction in the cosurfactant mixture

  16. Small angle neutron scattering study on a phase separation in a 3-component microemulsion system

    DEFF Research Database (Denmark)

    Seto, H.; Yokoi, E.; Komura, S.

    1993-01-01

    In literature, the 3-component microemulsion system consisting of AOT, water and n-decane is known to belong to 3D-Ising universality class so far. Recently, we have found that the critical exponent of the susceptibility is the meanfield value at near-critical region, and at the same time we have...

  17. Preparation of MgFe2O4 nanoparticles by microemulsion method and their characterization

    Czech Academy of Sciences Publication Activity Database

    Holec, Petr; Plocek, Jiří; Nižňanský, D.; Vejpravová, J.P.

    2009-01-01

    Roč. 51, č. 3 (2009), s. 301-305 ISSN 0928-0707 R&D Projects: GA ČR GA106/07/0949 Institutional research plan: CEZ:AV0Z40320502 Keywords : magnesium ferrite * microemulsion * nanoparticles Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.393, year: 2009

  18. Preparation of starch nanoparticles in water in oil microemulsion system and their drug delivery properties.

    Science.gov (United States)

    Wang, Xinge; Chen, Haiming; Luo, Zhigang; Fu, Xiong

    2016-03-15

    In this research, 1-hexadecyl-3-methylimidazolium bromide C16mimBr/butan-1-ol/cyclohexane/water ionic liquid microemulsion was prepared. The effects of n-alkyl alcohols, alkanes, water content and temperature on the properties of microemulsion were studied by dilution experiment. The microregion of microemulsion was identified by pseudo-ternary phase diagram and conductivity measurement. Then starch nanoparticles were prepared by water in oil (W/O) microemulsion-cross-linking methods with C16mimBr as surfactant. Starch nanoparticles with a mean diameter of 94.3nm and narrow size distribution (SD=3.3) were confirmed by dynamic light scattering (DLS). Scanning electron microscope (SEM) data revealed that starch nanoparticles were spherical granules with the size about 60nm. Moreover the results of Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) demonstrated the formation of cross-linking bonds in starch molecules. Finally, the drug loading and releasing properties of starch nanoparticles were investigated with methylene blue (MB) as drug model. This work may provide an efficient pathway to synthesis starch nanoparticles. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Embryo-fetal development toxicity of honokiol microemulsion intravenously administered to pregnant rats.

    Science.gov (United States)

    Zhang, Qianqian; Ye, Xiangfeng; Wang, Lingzhi; Peng, Bangjie; Zhang, Yingxue; Bao, Jie; Li, Wanfang; Wei, Jinfeng; Wang, Aiping; Jin, Hongtao; Chen, Shizhong

    2016-02-01

    The aim of this study was to evaluate the embryo-fetal development toxicity of honokiol microemulsion. The drug was intravenously injected to pregnant SD rats at dose levels of 0, 200, 600 and 2000 μg/kg/day from day 6-15 of gestation. All the pregnant animals were observed for body weights and any abnormal changes and subjected to caesarean-section on gestation day (GD) 20; all fetuses obtained from caesarean-section were assessed by external inspection, visceral and skeletal examinations. No treatment-related external alterations as well as visceral and skeletal malformations were observed in honokiol microemulsion groups. There was no significant difference in the body weight gain of the pregnant rats, average number of corpora lutea, and the gravid uterus weight in the honokiol microemulsion groups compared with the vehicle control group. However, at a dose level of 2000 μg/kg/day, there was embryo-fetal developmental toxicity observed, including a decrease in the body length and tail length of fetuses. In conclusion, the no-observed-adverse-effect level (NOAEL) of honokiol microemulsion is 600 μg/kg/day, 75 times above the therapeutic dosage and it has embryo-fetal toxicity at a dose level of 2000 μg/kg/day, which is approximately 250 times above the therapeutic dosage. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Analysis of small-angle scattering data from micelles and microemulsions

    DEFF Research Database (Denmark)

    Pedersen, J.S.

    1999-01-01

    The free-form methods for analyzing small-angle scattering data have, during the last years, found more widespread use for micelles and microemulsions. Recent developments have made them applicable also to systems with size polydispersity and particle correlations, however, model fitting still...

  1. Transdermal agomelatine microemulsion gel: pyramidal screening, statistical optimization and in vivo bioavailability.

    Science.gov (United States)

    Said, Mayada; Elsayed, Ibrahim; Aboelwafa, Ahmed A; Elshafeey, Ahmed H

    2017-11-01

    Agomelatine is a new antidepressant having very low oral drug bioavailability less than 5% due to being liable to extensive hepatic 1st pass effect. This study aimed to deliver agomelatine by transdermal route through formulation and optimization of microemulsion gel. Pyramidal screening was performed to select the most suitable ingredients combinations and then, the design expert software was utilized to optimize the microemulsion formulations. The independent variables of the employed mixture design were the percentages of capryol 90 as an oily phase (X 1 ), Cremophor RH40 and Transcutol HP in a ratio of (1:2) as surfactant/cosurfactant mixture 'S mix ' (X 2 ) and water (X 3 ). The dependent variables were globule size, optical clarity, cumulative amount permeated after 1 and 24 h, respectively (Q1 and Q 24 ) and enhancement ratio (ER). The optimized formula was composed of 5% oil, 45% S mix and 50% water. The optimized microemulsion formula was converted into carbopol-based gel to improve its retention on the skin. It enhanced the drug permeation through rat skin with an enhancement ratio of 37.30 when compared to the drug hydrogel. The optimum ME gel formula was found to have significantly higher C max , AUC 0-24 h and AUC 0-∞ than that of the reference agomelatine hydrogel and oral solution. This could reveal the prosperity of the optimized microemulsion gel formula to augment the transdermal bioavailability of agomelatine.

  2. Some aspects of nanocrystalline nickel and zinc ferrites processed using microemulsion technique

    NARCIS (Netherlands)

    Misra, RDK; Kale, A; Kooi, BJ; De Hosson, JTM

    2003-01-01

    Nanocrystalline nickel and zinc ferrites synthesised using a microemulsion technique were characterised by high resolution transmission electron microscopy and vibrating sample magnetometry. A narrow and uniform distribution of crystals of size range 5-8 nm, distinguished by a clear lack of

  3. Phase behaviour of an ionic microemulsion system as a function of the cosurfactant chain length

    NARCIS (Netherlands)

    Kegel, W.K.; Lekkerkerker, H.N.W.

    1993-01-01

    The phase behaviour of a microemulsion system consisting of equal volumes of brine and oil, sodium dodecyl sulphate (SDS) as surfactant and alcohols of different chain lengths (pentanol, hexanol and heptanol) as cosurfactant was studied. In the case of pentanol, at low surfactant concentrations and

  4. Microemulsion-based lycopene extraction: Effect of surfactants, co-surfactants and pretreatments.

    Science.gov (United States)

    Amiri-Rigi, Atefeh; Abbasi, Soleiman

    2016-04-15

    Lycopene is a potent antioxidant that has received extensive attention recently. Due to the challenges encountered with current methods of lycopene extraction using hazardous solvents, industry calls for a greener, safer and more efficient process. The main purpose of present study was application of microemulsion technique to extract lycopene from tomato pomace. In this respect, the effect of eight different surfactants, four different co-surfactants, and ultrasound and enzyme pretreatments on lycopene extraction efficiency was examined. Experimental results revealed that application of combined ultrasound and enzyme pretreatments, saponin as a natural surfactant, and glycerol as a co-surfactant, in the bicontinuous region of microemulsion was the optimal experimental conditions resulting in a microemulsion containing 409.68±0.68 μg/glycopene. The high lycopene concentration achieved, indicates that microemulsion technique, using a low-cost natural surfactant could be promising for a simple and safe separation of lycopene from tomato pomace and possibly from tomato industrial wastes. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Novel extraction induced by microemulsion breaking: a model study for Hg extraction from Brazilian gasoline.

    Science.gov (United States)

    Vicentino, Priscila O; Cassella, Ricardo J

    2017-01-01

    This paper proposes a novel approach for the extraction of Hg from Brazilian gasoline samples: extraction induced by microemulsion breaking (EIMB). In this approach, a microemulsion is formed by mixing the sample with n-propanol and HCl. Afterwards, the microemulsion is destabilized by the addition of water and the two phases are separated: (i) the top phase, containing the residual gasoline and (ii) the bottom phase, containing the extracted analyte in a medium containing water, n-propanol and the ethanol originally present in the gasoline sample. The bottom phase is then collected and the Hg is measured by cold vapor atomic absorption spectrometry (CV-AAS). This model study used Brazilian gasoline samples spiked with Hg (organometallic compound) to optimize the process. Under the optimum extraction conditions, the microemulsion was prepared by mixing 8.7mL of sample with 1.2mL of n-propanol and 0.1mL of a 10molL -1 HCl solution. Emulsion breaking was induced by adding 300µL of deionized water and the bottom phase was collected for the measurement of Hg. Six samples of Brazilian gasoline were spiked with Hg in the organometallic form and recovery percentages in the range of 88-109% were observed. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Use of micro-emulsion technology for the directed evolution of antibodies.

    Science.gov (United States)

    Buhr, Diane L; Acca, Felicity E; Holland, Erika G; Johnson, Katie; Maksymiuk, Gail M; Vaill, Ada; Kay, Brian K; Weitz, David A; Weiner, Michael P; Kiss, Margaret M

    2012-09-01

    Affinity reagents, such as antibodies, are needed to study protein expression patterns, sub-cellular localization, and post-translational modifications in complex mixtures and tissues. Phage Emulsion, Secretion, and Capture (ESCape) is a novel micro-emulsion technology that utilizes water-in-oil (W/O) emulsions for the identification and isolation of cells secreting phage particles that display desirable antibodies. Using this method, a large library of antibody-displaying phage will bind to beads in individual compartments. Rather than using biopanning on a large mixed population, phage micro-emulsion technology allows us to individually query clonal populations of amplified phage against the antigen. The use of emulsions to generate microdroplets has the promise of accelerating phage selection experiments by permitting fine discrimination of kinetic parameters for binding to targets. In this study, we demonstrate the ability of phage micro-emulsion technology to distinguish two scFvs with a 300-fold difference in binding affinities (100nM and 300pM, respectively). In addition, we describe the application of phage micro-emulsion technology for the selection of scFvs that are resistant to elevated temperatures. Copyright © 2012. Published by Elsevier Inc.

  7. Anti-Inflammatory Activity of Babassu Oil and Development of a Microemulsion System for Topical Delivery

    Science.gov (United States)

    Reis, Mysrayn Y. F. A.; dos Santos, Simone M.; Silva, Danielle R.; Navarro, Daniela M. A. Ferraz; Santos, Geanne K. N.; Hallwass, Fernando; Bianchi, Otávio; Silva, Alexandre G.; Melo, Janaína V.; Machado, Giovanna; Saraiva, Karina L. A.

    2017-01-01

    Babassu oil extraction is the main income source in nut breakers communities in northeast of Brazil. Among these communities, babassu oil is used for cooking but also medically to treat skin wounds and inflammation, and vulvovaginitis. This study aimed to evaluate the anti-inflammatory activity of babassu oil and develop a microemulsion system with babassu oil for topical delivery. Topical anti-inflammatory activity was evaluated in mice ear edema using PMA, arachidonic acid, ethyl phenylpropiolate, phenol, and capsaicin as phlogistic agents. A microemulsion system was successfully developed using a Span® 80/Kolliphor® EL ratio of 6 : 4 as the surfactant system (S), propylene glycol and water (3 : 1) as the aqueous phase (A), and babassu oil as the oil phase (O), and analyzed through conductivity, SAXS, DSC, TEM, and rheological assays. Babassu oil and lauric acid showed anti-inflammatory activity in mice ear edema, through inhibition of eicosanoid pathway and bioactive amines. The developed formulation (39% A, 12.2% O, and 48.8% S) was classified as a bicontinuous to o/w transition microemulsion that showed a Newtonian profile. The topical anti-inflammatory activity of microemulsified babassu oil was markedly increased. A new delivery system of babassu microemulsion droplet clusters was designed to enhance the therapeutic efficacy of vegetable oil. PMID:29430254

  8. Shear-induced nano-macro structural transition in a polymeric bicontinuous microemulsion

    DEFF Research Database (Denmark)

    Krishnan, K.; Almdal, K.; Burghardt, W.R.

    2001-01-01

    structure. In situ neutron scattering shows flow-induced anisotropy in the nanometer-scale microemulsion structure at moderate shear rates, while higher rates induce bulk phase separation, with micron-size morphology, which is characterized with in situ light scattering and optical microscopy....

  9. Anti-Inflammatory Activity of Babassu Oil and Development of a Microemulsion System for Topical Delivery

    Directory of Open Access Journals (Sweden)

    Mysrayn Y. F. A. Reis

    2017-01-01

    Full Text Available Babassu oil extraction is the main income source in nut breakers communities in northeast of Brazil. Among these communities, babassu oil is used for cooking but also medically to treat skin wounds and inflammation, and vulvovaginitis. This study aimed to evaluate the anti-inflammatory activity of babassu oil and develop a microemulsion system with babassu oil for topical delivery. Topical anti-inflammatory activity was evaluated in mice ear edema using PMA, arachidonic acid, ethyl phenylpropiolate, phenol, and capsaicin as phlogistic agents. A microemulsion system was successfully developed using a Span® 80/Kolliphor® EL ratio of 6 : 4 as the surfactant system (S, propylene glycol and water (3 : 1 as the aqueous phase (A, and babassu oil as the oil phase (O, and analyzed through conductivity, SAXS, DSC, TEM, and rheological assays. Babassu oil and lauric acid showed anti-inflammatory activity in mice ear edema, through inhibition of eicosanoid pathway and bioactive amines. The developed formulation (39% A, 12.2% O, and 48.8% S was classified as a bicontinuous to o/w transition microemulsion that showed a Newtonian profile. The topical anti-inflammatory activity of microemulsified babassu oil was markedly increased. A new delivery system of babassu microemulsion droplet clusters was designed to enhance the therapeutic efficacy of vegetable oil.

  10. Microemulsion flame pyrolysis for hopcalite nanoparticle synthesis: a new concept for catalyst preparation

    OpenAIRE

    Kaskel, Stefan; Biemelt, Tim; Wegner, Karl; Teichert, Johannes

    2016-01-01

    A new route to highly active hopcalite catalysts via flame spray pyrolysis of an inverse microemulsion precursor is reported. The nitrate derived nanoparticles are around 15 nm in diameter and show excellent conversion of CO under ambient conditions, outperforming commercial reference hopcalite materials produced by co-precipitation.

  11. Microemulsion flame pyrolysis for hopcalite nanoparticle synthesis: a new concept for catalyst preparation.

    Science.gov (United States)

    Biemelt, T; Wegner, K; Teichert, J; Kaskel, S

    2015-04-07

    A new route to highly active hopcalite catalysts via flame spray pyrolysis of an inverse microemulsion precursor is reported. The nitrate derived nanoparticles are around 15 nm in diameter and show excellent conversion of CO under ambient conditions, outperforming commercial reference hopcalite materials produced by co-precipitation.

  12. On Metal Segregation of Bimetallic Nanocatalysts Prepared by a One-Pot Method in Microemulsions

    Directory of Open Access Journals (Sweden)

    Concha Tojo

    2017-02-01

    Full Text Available A comparative study on different bimetallic nanocatalysts prepared from microemulsions using a one-pot method has been carried out. The analysis of experimental observations, complemented by simulation studies, provides detailed insight into the factors affecting nanoparticle architecture: (1 The metal segregation in a bimetallic nanocatalysts is the result of the combination of three main kinetic parameters: the reduction rate of metal precursors (related to reduction standard potentials, the material intermicellar exchange rate (determined by microemulsion composition, and the metal precursors concentration; (2 A minimum difference between the reduction standard potentials of the two metals of 0.20 V is needed to obtain a core-shell structure. For values ∆ε0 smaller than 0.20 V the obtaining of alloys cannot be avoided, neither by changing the microemulsion nor by increasing metal concentration; (3 As a rule, the higher the film flexibility around the micelles, the higher the degree of mixture in the nanocatalyst; (4 A minimum concentration of metal precursors is required to get a core-shell structure. This minimum concentration depends on the microemulsion flexibility and on the difference in reduction rates.

  13. Development and evaluation of a microemulsion formulation for transdermal delivery of terbinafine.

    Science.gov (United States)

    Baboota, S; Al-Azaki, A; Kohli, K; Ali, J; Dixit, N; Shakeel, F

    2007-01-01

    The aim of the present study is to develop and evaluate microemulsion formulations for Terbinafine (TB) with a view to enhance its permeability through the skin and provide release for 24 h. Various o/w microemulsions were prepared by the spontaneous emulsification method. Oleic acid was chosen as the oil phase, Caprylo caproyl macrogol-8- glyceride (Labrasol S) and purified diethylene glycol monoethyl ether (Transcutol P) were used as surfactant and cosurfactant, respectively, on the basis of solubility studies. Pseudoternary phase diagrams were constructed to obtain the concentration range of oil, surfactant, cosurfactant, and water for microemulsion formulation. The optimized microemulsion consisted of 2% w/w TB, 8% w/w oleic acid, 31% w/w labrasol S, 31% w/w transcutol P, and 30% w/w distilled water. Permeability parameters like Jss and Kp were found to be significantly higher for formulation F4 as compared to other formulations (P activity against Candida albicans and Aspergillus flavus as compared to marketed product (P < 0.05).

  14. Mucoadhesive microemulsion of ibuprofen: design and evaluation for brain targeting efficiency through intranasal route

    Directory of Open Access Journals (Sweden)

    Surjyanarayan Mandal

    2015-09-01

    Full Text Available This study aimed at designing mucoadhesive microemulsion gel to enhance the brain uptake of Ibuprofen through intranasal route. Ibuprofen loaded mucoadhesive microemulsion (MMEI was developed by incorporating polycarbophil as mucoadhesive polymer into Capmul MCM based optimal microemulsion (MEI and was subjected to characterization, stability, mucoadhesion and naso-ciliotoxicity study. Brain uptake of ibuprofen via nasal route was studied by performing biodistribution study in Swiss albino rats. MEI was found to be transparent, stable and non ciliotoxic with 66.29 ± 4.15 nm, -20.9 ± 3.98 mV and 98.66 ± 1.01% as average globule size, zeta potential and drug content respectively. Transmission Electron Microscopy (TEM study revealed the narrow globule size distribution of MEI. Following single intranasal administration of MMEI and MEI at a dose of 2.86 mg/kg, uptake of ibuprofen in the olfactory bulb was around 3.0 and 1.7 folds compared with intravenous injection of ibuprofen solution (IDS. The ratios of AUC in brain tissues to that in plasma obtained after nasal administration of MMEI were significantly higher than those after intravenous administration of IDS. Findings of the present investigation revealed that the developed mucoadhesive microemulsion gel could be a promising approach for brain targeting of ibuprofen through intranasal route.

  15. Preparation, characterization and relative bioavailability of oral elemene o/w microemulsion

    Science.gov (United States)

    Zeng, Zhaowu; Zhou, Guanglin; Wang, Xiaoli; Huang, Eric Zhijian; Zhan, Xiaori; Liu, Jun; Wang, Shuling; Wang, Anming; Li, Haifeng; Pei, Xiaolin; Xie, Tian

    2010-01-01

    The objective was to develop an elemene oil/water (o/w) microemulsion and evaluate its characteristics and oral relative bioavailability in rats. Elemene was used as the oil phase and drug, polysorbate 80 as a surfactant along with ethanol, propylene glycol, and glycerol as the cosurfactants. The microemulsion was prepared by mixing method, or ultrasonication method in an ultrasonic bath. Its three-dimensional response surface diagram was drawn by Mathcad software. The microemulsion was characterized by visual observation, cross-polarized microscopy, size, zeta potential, acidity, viscosity, and surface tension measurement. The drug content and entrapment efficiency were determined by ultra fast liquid chromatography (UFLC) and liquid surface method. Blood was drawn from rats at different time points after oral administration of an elemene microemulsion or a commercial elemene emulsion for measurement of the drug in plasma by UFLC to establish the pharmacokinetic parameters and relative bioavailability. The elemene microemulsion as a clarified and isotropic system containing 1% elemene (w/v), 5% ethanol (v/v), 15% propylene glycol (v/v), 15% glycerol (v/v), and 5% polysorbate 80 (w/v), was characterized as (57.7 ± 2.8) nm in size, 0.485 ± 0.032 in polydispersity index, (3.2 ± 0.4) mv in zeta potential, (5.19 ± 0.08) in pH, 6 mpa·s in viscosity, (31.8 ± 0.3) mN·m−1 in surface tension, (8.273 ± 0.018) mg·mL−1 in content of β-elemene, and (99.81 ± 0.24)% in average entrapment efficiency. The area under the concentration-time curves from 0 h to 24 h (AUC0→24h) of the elemene microemulsion and commercial elemene emulsion were integrated to be 3.092 mg·h·L−1 and 1.896 mg·h·L−1 respectively, yielding a relative bioavailability of 163.1%. The present study demonstrates the elemene microemulsion as a new formulation with ease of preparation, high entrapment efficiency, excellent clarity, good stability, and improved bioavailability. PMID:20856831

  16. Preparation, characterization and relative bioavailability of oral elemene o/w microemulsion.

    Science.gov (United States)

    Zeng, Zhaowu; Zhou, Guanglin; Wang, Xiaoli; Huang, Eric Zhijian; Zhan, Xiaori; Liu, Jun; Wang, Shuling; Wang, Anming; Li, Haifeng; Pei, Xiaolin; Xie, Tian

    2010-09-07

    The objective was to develop an elemene oil/water (o/w) microemulsion and evaluate its characteristics and oral relative bioavailability in rats. Elemene was used as the oil phase and drug, polysorbate 80 as a surfactant along with ethanol, propylene glycol, and glycerol as the cosurfactants. The microemulsion was prepared by mixing method, or ultrasonication method in an ultrasonic bath. Its three-dimensional response surface diagram was drawn by Mathcad software. The microemulsion was characterized by visual observation, cross-polarized microscopy, size, zeta potential, acidity, viscosity, and surface tension measurement. The drug content and entrapment efficiency were determined by ultra fast liquid chromatography (UFLC) and liquid surface method. Blood was drawn from rats at different time points after oral administration of an elemene microemulsion or a commercial elemene emulsion for measurement of the drug in plasma by UFLC to establish the pharmacokinetic parameters and relative bioavailability. The elemene microemulsion as a clarified and isotropic system containing 1% elemene (w/v), 5% ethanol (v/v), 15% propylene glycol (v/v), 15% glycerol (v/v), and 5% polysorbate 80 (w/v), was characterized as (57.7 ± 2.8) nm in size, 0.485 ± 0.032 in polydispersity index, (3.2 ± 0.4) mv in zeta potential, (5.19 ± 0.08) in pH, 6 mpa·s in viscosity, (31.8 ± 0.3) mN·m(-1) in surface tension, (8.273 ± 0.018) mg·mL(-1) in content of β-elemene, and (99.81 ± 0.24)% in average entrapment efficiency. The area under the concentration-time curves from 0 h to 24 h (AUC(0→24h)) of the elemene microemulsion and commercial elemene emulsion were integrated to be 3.092 mg·h·L(-1) and 1.896 mg·h·L(-1) respectively, yielding a relative bioavailability of 163.1%. The present study demonstrates the elemene microemulsion as a new formulation with ease of preparation, high entrapment efficiency, excellent clarity, good stability, and improved bioavailability.

  17. Spontaneous and Flow-Driven Interfacial Phase Change: Dynamics of Microemulsion Formation at the Pore Scale.

    Science.gov (United States)

    Tagavifar, Mohsen; Xu, Ke; Jang, Sung Hyun; Balhoff, Matthew T; Pope, Gary A

    2017-11-14

    The dynamic behavior of microemulsion-forming water-oil-amphiphiles mixtures is investigated in a 2.5D micromodel. The equilibrium phase behavior of such mixtures is well-understood in terms of macroscopic phase transitions. However, what is less understood and where experimental data are lacking is the coupling between the phase change and the bulk flow. Herein, we study the flow of an aqueous surfactant solution-oil mixture in porous media and analyze the dependence of phase formation and spatial phase configurations on the bulk flow rate. We find that a microemulsion forms instantaneously as a boundary layer at the initial surface of contact between the surfactant solution and oil. The boundary layer is temporally continuous because of the imposed convection. In addition to the imposed flow, we observe spontaneous pulsed Marangoni flows that drag the microemulsion and surfactant solution into the oil stream, forming large (macro)emulsion droplets. The formation of the microemulsion phase at the interface distinguishes the situation from that of the more common Marangoni flow with only two phases present. Additionally, an emulsion forms via liquid-liquid nucleation or the Ouzo effect (i.e., spontaneous emulsification) at low flow rates and via mechanical mixing at high flow rates. With regard to multiphase flow, contrary to the common belief that the microemulsion is the wetting liquid, we observe that the minor oil phase wets the solid surface. We show that a layered flow pattern is formed because of the out-of-equilibrium phase behavior at high volumetric flow rates (order of 2 m/day) where advection is much faster than the diffusive interfacial mass transfer and transverse mixing, which promote equilibrium behavior. At lower flow rates (order of 30 cm/day), however, the dynamic and equilibrium phase behaviors are well-correlated. These results clearly show that the phase change influences the macroscale flow behavior.

  18. Development of Microemulsion Based Nabumetone Transdermal Delivery For Treatment of Arthritis.

    Science.gov (United States)

    Jagdale, Swati; Deore, Gokul; Chabukswar, Anuruddha

    2018-02-26

    Background Nabumetone is biopharmaceutics classification system (BCS) class II drug, widely used in the treatment of osteoarthritis and rheumatoid arthritis. The most frequently reported adverse reactions for the drug involve disturbance in gastrointestinal tract , diarrhea, dyspepsia and abdominal pain. Microemulgel has advantages of microemulsion for improving solubility for hydrophobic drug. Patent literature had shown that the work for drug has been carried on spray chilling, enteric coated tablet, and topical formulation which gave idea for present research work for development of transdermal delivery. Objective Objective of the present research work was to optimize transdermal microemulgel delivery for Nabumetone for treatment of arthritis. Method Oil, surfactant and co-surfactant were selected based on solubility study for the drug. Gelling agents used were Carbopol 934 and HPMC K100M. Optimization was carried out using 32 factorial design. Characterization and evaluation were carried out for microemulsion and microemulsion based gel. Results Field emission-scanning electron microscopy (FE-SEM) study of the microemulsion revealed globules of 50-200 nm size . Zeta potential -9.50 mV indicated good stability of microemulsion. Globule size measured by dynamic light scattering (zetasizer) was 160 nm. Design expert gave optimized batch as F7 which contain 0.2% w/w drug, 4.3% w/w liquid paraffin, 0.71% w/w tween 80, 0.35% w/w propylene glycol, 0.124% w/w Carbopol 934, 0.187% w/w HPMC K100M and 11.68% w/w water. In-vitro diffusion study for F7 batch showed 99.16±2.10 % drug release through egg membrane and 99.15±2.73% drug release in ex-vivo study. Conclusion Nabumetone microemulgel exhibiting good in-vitro and ex-vivo controlled drug release was optimized. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  19. Preparation, characterization and in vitro evaluation of microemulsion of raloxifene hydrochloride.

    Science.gov (United States)

    Golmohammadzadeh, Shiva; Farhadian, Nafiseh; Biriaee, Amir; Dehghani, Faranak; Khameneh, Bahman

    2017-10-01

    Raloxifene hydrochloride (RLX) is a selective estrogen receptor modulator which is orally used for treatment of osteoporosis and prevention of breast cancer. The drug has low aqueous solubility and bioavailability. The aim of the present study is to formulate and characterize oil-in-water microemulsion systems for oral delivery of RLX. To enhance the drug aqueous solubility, microemulsion based on sesame oil was prepared. Sesame oil and Tween 80 were selected as the drug solvent oil and surfactant, respectively. In the first and second formulations, Edible glycerin and Span 80 were applied as co-surfactant, respectively. Pseudo-ternary phase diagrams showed that the best surfactant/co-surfactant ratios in the first and second formulations were 4:1 and 9:1, respectively. The particle size of all free drug-loaded and drug loaded samples were in the range of 31.25 ± 0.3 nm and 60.9 ± 0.1 nm, respectively. Electrical conductivity coefficient and refractive index of all microemulsion samples confirmed the formation of oil-in-water type of microemulsion. In vitro drug release profile showed that after 24 hours, 46% and 63% of the drug released through the first formulation in 0.1% (w/v) Tween 80 in distilled water as a release medium and phosphate buffer solution (PBS) at pH = 5.5, respectively. These values were changed to 57% and 98% for the second formulation. Results confirmed that the proposed microemulsion system containing RLX could improve and control the drug release profile in comparison to conventional dosage form.

  20. Uniform-sized silicone oil microemulsions: preparation, investigation of stability and deposition on hair surface.

    Science.gov (United States)

    Nazir, Habiba; Lv, Piping; Wang, Lianyan; Lian, Guoping; Zhu, Shiping; Ma, Guanghui

    2011-12-01

    Emulsions are commonly used in foods, pharmaceuticals and home-personal-care products. For emulsion based products, it is highly desirable to control the droplet size distribution to improve storage stability, appearance and in-use property. We report preparation of uniform-sized silicone oil microemulsions with different droplets diameters (1.4-40.0 μm) using SPG membrane emulsification technique. These microemulsions were then added into model shampoos and conditioners to investigate the effects of size, uniformity, and storage stability on silicone oil deposition on hair surface. We observed much improved storage stability of uniform-sized microemulsions when the droplets diameter was ≤22.7 μm. The uniform-sized microemulsion of 40.0 μm was less stable but still more stable than non-uniform sized microemulsions prepared by conventional homogenizer. The results clearly indicated that uniform-sized droplets enhanced the deposition of silicone oil on hair and deposition increased with decreasing droplet size. Hair switches washed with small uniform-sized droplets had lower values of coefficient of friction compared with those washed with larger uniform and non-uniform droplets. Moreover the addition of alginate thickener in the shampoos and conditioners further enhanced the deposition of silicone oil on hair. The good correlation between silicone oil droplets stability, deposition on hair and resultant friction of hair support that droplet size and uniformity are important factors for controlling the stability and deposition property of emulsion based products such as shampoo and conditioner. Copyright © 2011 Elsevier Inc. All rights reserved.

  1. The comparison of oxidative thermokinetics between emulsion and microemulsion diesel fuel

    International Nuclear Information System (INIS)

    Leng, Lijian; Yuan, Xingzhong; Zeng, Guangming; Wang, Hou; Huang, Huajun; Chen, Xiaohong

    2015-01-01

    Highlights: • Microemulsion fuel (>90 days) was much more stable than emulsion (≈2 days). • Microemulsification decreased activation energy of the fuel system by 5 kJ mol −1 . • Emulsification increased activation energy of the fuel system by 15 kJ mol −1 . • Microemulsification was more competitive for fuel upgrading than emulsification. - Abstract: Water fuel emulsion has been widely studied with the advantages of saving energy, enhancing engine torque, improving engine performance, and reducing the pollutant emissions. However, it has unfavorable disadvantages such as phase separation and long ignition delay. Water fuel microemulsion with rhamnolipid as the surfactant was formed in this study and characterized in comparison to water fuel emulsion. Water fuel microemulsion was thermodynamically stable without phase separation after 90 days vs. the milky-white emulsion fuel, separated within 2 days. In the thermogravimetric analysis, the TG and DTG curves were shifted to higher temperatures as the increment of heating rate. However, the shift for emulsion at 40 K min −1 was inconspicuous, which implies the reduction in heat transfer, mass transfer, and vaporization rates and further the lengthened ignition delay upon combustion in diesel engine. The activation energies (E a ) predicted by Ozawa–Flynn–Wall (OFW), Kissinger–Akhira–Sunose (KAS), and Starink’s methods indicate that the formation of microemulsion could decrease the activation energy of the fuel by about 5 kJ mol −1 , while the formation of emulsion would increase by 15 kJ mol −1 . The lower activation energy of microemulsion fuel is an indication of easy ignition or shortened ignition delay. Thus, microemulsification may be a more competitive technique for fuel upgrading compared to emulsification

  2. CoFe2O4-TiO2 Hybrid Nanomaterials: Synthesis Approaches Based on the Oil-in-Water Microemulsion Reaction Method

    Directory of Open Access Journals (Sweden)

    Arturo Adrián Rodríguez-Rodríguez

    2017-01-01

    Full Text Available CoFe2O4 nanoparticles decorated and wrapped with TiO2 nanoparticles have been prepared by mixing well-dispersed CoFe2O4 with amorphous TiO2 (impregnation approach and growing amorphous TiO2 over the magnetic core (seed approach, respectively, followed by thermal treatment to achieve TiO2 crystallinity. Synthesis strategies were based on the oil-in-water microemulsion reaction method. Thermally treated nanomaterials were characterized in terms of structure, morphology, and composition, to confirm hybrid nanoparticles formation and relate with the synthesis approaches; textural, optical, and magnetic properties were evaluated. X-ray diffraction revealed coexistence of cubic spinel-type CoFe2O4 and tetragonal anatase TiO2. Electron microscopy images depicted crystalline nanoparticles (sizes below 25 nm, with homogeneous Ti distribution for the hybrid nanoparticles synthesized by seed approach. EDX microanalysis and ICP-AES corroborated established chemical composition. XPS evidenced chemical states, as well as TiO2 predominance over CoFe2O4 surface. According to BET measurements, the hybrid nanoparticles were mesoporous. UV-Vis spectroscopy showed optical response along the UV-visible light region. Magnetic properties suggested the breaking order of magnetic domains due to modification with TiO2, especially for mediated seed approach sample. The properties of the obtained hybrid nanoparticles were different in comparison with its individual components. The results highlight the usefulness of designed microemulsion approaches for the straightforward synthesis of CoFe2O4-TiO2 nanostructured hybrids.

  3. Antioxidant and antimicrobial activities of clove bud essential oil and eugenol nanoparticles in alcohol-free microemulsion.

    Science.gov (United States)

    Hamed, Said Fatouh; Sadek, Zainab; Edris, Amr

    2012-01-01

    Clove bud essential oil (CEO) and its major individual phenolic constituent eugenol were formulated as nanoparticles in water-based microemulsion systems. The oil titration method was used to incorporate different amounts of the oil and eugenol in the micellar solution of Tween-20. The Antioxidant and antimicrobial activities were evaluated using the DPPH* free radical scavenging assay and the agar disc dilution method, respectively. Results showed that microemulsion improved the evaluated activities of CEO and eugenol compared with the crude counterparts. Individual eugenol microemulsion was more effective than CEO microemulsion which contained only 61.7% eugenol among its constituents. The results of this study could have potential applications in water-based disinfectants, preservation and flavoring of food and in personal hygiene products. It may also have promising applications in the nutraceutical and functional beverage field.

  4. Topical microemulsion containing Punica granatum extract: its control over skin erythema and melanin in healthy Asian subjects.

    Science.gov (United States)

    Parveen, Rashida; Akhtar, Naveed; Mahmood, Tariq

    2014-12-01

    Punica granatum is apotent source of polyphenolic compounds with strong free radicals scavenging activity. The skin lightening effects of Punica granatum are assumed due to ellagic acid which acts by chelating copper at the active site of tyrosinase. To explore a topical microemulsion (O/W) of pomegranate (Punica granatum) extract for its control on skin erythema and melanin. Microemulsions were formulated using a polysorbate surfactant (Tween 80(®)) along with cosurfactant (propylene glycol) and were characterized regarding their stability. The placebo microemulsion (without extract) and the active microemulsion (containing Punica extract) were applied in a split face fashion by the volunteers (n = 11) for a period of 12 weeks. Skin erythema and melanin were measured at baseline and after every 15 days to determine any effect produced by these formulations. Active formulation showed a significant impact on skin erythema and melanin (p Punica granatum extract for conditions where elevated skin melanin and erythema have significantly prone skin physiology.

  5. Polymeric Bicontinuous Microemulsions as Templates for Nanostructured Materials

    Science.gov (United States)

    Jones, Brad Howard

    Ternary blends of two homopolymers and a diblock copolymer can self-assemble into interpenetrating, three dimensionally-continuous networks with a characteristic length scale of ˜ 100 nm. In this thesis, it is shown that these liquid phases, known as polymeric bicontinuous microemulsions (BμE), can be designed as versatile precursors to nanoporous materials having pores with uniform sizes of ˜ 100 nm. The model blends from which the porous materials are derived are composed of polyethylene (PE) and a sacrificial polyolefin. The liquid BμE structure is captured by crystallization of the PE, and a three-dimensionally continuous pore network with a narrow pore size distribution is generated by selective extraction of the sacrificial component. The original BμE structure is retained in the resultant nanoporous PE. This monolithic material is then used as a template in the synthesis of other nanoporous materials for which structural control at the nm scale has traditionally been difficult to achieve. These materials, which include a high-temperature ceramic, polymeric thermosets, and a conducting polymer, are produced by a simple nanocasting process, providing an inverse replica of the PE template. On account of the BμE structure of the template, the product materials also possess three-dimensionally continuous pore networks with narrow size distributions centered at ˜ 100 nm. The PE template is further used as a template for the production of hierarchically structured inorganic and polymeric materials by infiltration of mesostructured compounds into its pore network. In the former case, a hierarchically porous SiO2 material is demonstrated, simultaneously possessing two discrete, bicontinuous pore networks with sizes differing by over an order of magnitude. Finally, the templating procedures are extended to thin films supported on substrates and novel conductive polymer films are synthesized. The work described herein represents an unprecedented suite of

  6. KDP Aqueous Solution-in-Oil Microemulsion for Ultra-Precision Chemical-Mechanical Polishing of KDP Crystal

    Directory of Open Access Journals (Sweden)

    Hui Dong

    2017-03-01

    Full Text Available A novel functional KH2PO4 (KDP aqueous solution-in-oil (KDP aq/O microemulsion system for KDP crystal ultra-precision chemical-mechanical polishing (CMP was prepared. The system, which consisted of decanol, Triton X-100, and KH2PO4 aqueous solution, was available at room temperature. The functional KDP aq/O microemulsion system was systematically studied and applied as polishing solution to KDP CMP technology. In this study, a controlled deliquescent mechanism was proposed for KDP polishing with the KDP aq/O microemulsion. KDP aqueous solution, the chemical etchant in the polishing process, was caged into the micelles in the microemulsion, leading to a limitation of the reaction between the KDP crystal and KDP aqueous solution only if the microemulsion was deformed under the effect of the external force. Based on the interface reaction dynamics, KDP aqueous solutions with different concentrations (cKDP were applied to replace water in the traditional water-in-oil (W/O microemulsion. The practicability of the controlled deliquescent mechanism was proved by the decreasing material removal rate (MRR with the increasing of the cKDP. As a result, the corrosion pits on the KDP surface were avoided to some degree. Moreover, the roughnesses of KDP with KDP aq/O microemulsion (cKDP was changed from 10 mM to 100 mM as polishing solutions were smaller than that with the W/O microemulsion. The smallest surface root-mean-square roughness of 1.5 nm was obtained at a 30 mmol/L KDP aq solution, because of the most appropriate deliquescent rate and MRR.

  7. Intravenous microemulsion of docetaxel containing an anti-tumor synergistic ingredient (Brucea javanica oil: formulation and pharmacokinetics

    Directory of Open Access Journals (Sweden)

    Ma S

    2013-10-01

    Full Text Available Shilin Ma,1 Fen Chen,1 Xiaohui Ye,2 Yingjie Dong,2 Yingna Xue,1 Heming Xu,1 Wenji Zhang,1 Shuangshuang Song,1 Li Ai,2 Naixian Zhang,2 Weisan Pan1 1School of Pharmacy, Shenyang Pharmaceutical University, Shenyang, 2Liaoning Institute of Pharmaceutical Industry, Liaoning, The People's Republic of China Abstract: The purpose of this study was to develop a docetaxel microemulsion containing an anti-tumor synergistic ingredient (Brucea javanica oil and to investigate the characteristics of the microemulsion. Brucea javanica oil contains oleic acid and linoleic acids that have been shown by animal and human studies to inhibit tumor formation. The microemulsion containing Brucea javanica oil, medium-chain triglyceride, soybean lecithin, Solutol®HS 15, PEG 400, and water was developed for docetaxel intravenous administration. A formulation with higher drug content, lower viscosity, and smaller particle size was developed. The droplet size distribution of the dispersed phase of the optimized microemulsion was 13.5 nm, determined using a dynamic light scattering technique. The small droplet size enabled the microemulsion droplets to escape from uptake and phagocytosis by the reticuloendothelial system and increased the circulation time of the drug. The zeta potential was -41.3 mV. The optimized microemulsion was pale yellow, transparent, and non-opalescent in appearance. The value of the combination index was 0.58, showing that there was a synergistic effect when docetaxel was combined with Brucea javanica oil. After a single intravenous infusion dose (10 mg/kg in male Sprague Dawley rats, the area under the curve of the microemulsion was higher and the half-time was longer compared with that of docetaxel solution alone, and showed superior pharmacokinetic characteristics. These results indicate that this preparation of docetaxel in emulsion is likely to provide an excellent prospect for clinical tumor treatment. Keywords: microemulsion, docetaxel

  8. Preparation and Characterization of Cyanocobalamin (Vit B12 Microemulsion Properties and Structure for Topical and Transdermal Application

    Directory of Open Access Journals (Sweden)

    Anayatollah Salimi

    2013-07-01

    This study showed that both microemulsions provided good solubility of Vit B12 with a wide range of internal structure. Low water solubilization capacity is a common property of microemulsions that can affect drug release and permeability through the skin. Based on Vit B12 properties, specially, intermediate oil and water solubility, better drug partitioning into the skin may be obtained by traditional formulations with wide range of structure and high amount of free and bounded water.

  9. Formulation Optimization and Ex Vivo and In Vivo Evaluation of Celecoxib Microemulsion-Based Gel for Transdermal Delivery.

    Science.gov (United States)

    Cao, Mengyuan; Ren, Lili; Chen, Guoguang

    2017-08-01

    Celecoxib (CXB) is a poorly aqueous solubility sulfonamide non-steroidal anti-inflammatory drug (NSAID). Hence, the formulation of CXB was selected for solubilization and bioavailability. To find out suitable formulation for microemulsion, the solubility of CXB in triacetin (oil phase), Tween 80 (surfactant), and Transcutol-P (co-surfactant) was screened respectively and optimized by using orthogonal experimental design. The Km value and concentration of oil, S mix , and water were confirmed by pseudo-ternary phase diagram studies and central composite design. One percent carbopol 934 was added to form CXB microemulsion-based gel. The final formulation was evaluated for its appearance, pH, viscosity, stability, drug content determination, globule size, and zeta potential. Its ex vivo drug permeation and the in vivo pharmacokinetic was investigated. Further research was performed to ensure the safety and validity by skin irritation study and in vivo anti-inflammatory activity study. Ex vivo permeation study in mice was designed to compare permeation and transdermal ability between microemulsion formulation and conventional gel. The results revealed that optimized microemulsion-based gel gained higher permeation based on smaller globule size and high drug loading of microemulsion. Transdermal ability was also greatly improved. Bioavailability was compared to market Celebrex® by the in vivo pharmacokinetic study in rabbits. The results indicated that CXB microemulsion-based gel had better bioavailability than Celebrex®.

  10. Formulation and In-vitro Evaluation of Tretinoin Microemulsion as a Potential Carrier for Dermal Drug Delivery.

    Science.gov (United States)

    Mortazavi, Seyed Alireza; Pishrochi, Sanaz; Jafari Azar, Zahra

    2013-01-01

    In this study, tretinoin microemulsion has been formulated based on phase diagram studies by changing the amounts and proportions of inactive ingredients, such as surfactants, co-surfactants and oils. The effects of these variables have been determined on microemulsion formation, particle size of the dispersed phase and release profile of tretinoin from microemulsion through dialysis membrane. In released studies, static Franz diffusion cells mounted with dialysis membrane were used. Sampling was conducted every 3 h at room temperature over a period of 24 h. The amount of released drug was measured with UV-spectrophotometer and the percentage of drug released was calculated. Based on the results obtained, the oil phase concentration had a proportional effect on particle size which can consequently influence on drug release. The particle size and the amount of released drug were affected by the applied surfactants. The components of the optimized microemulsion formulation were 15% olive oil, 12% propylene glycol (as co-surfactant), 33% Tween(®)80 (as surfactant) and 40% distilled water, which was tested for viscosity and rheological behavior. The prepared tretinoin microemulsion showed pseudoplastic-thixotropic behavior. The profile of drug release follows zero order kinetics. The optimized tretinoin microemulsion showed enhanced in-vitro release profile compared to the commercial gels and creams.

  11. Formation, thermodynamic properties, microstructures and antimicrobial activity of mixed cationic/non-ionic surfactant microemulsions with isopropyl myristate as oil.

    Science.gov (United States)

    Bardhan, Soumik; Kundu, Kaushik; Das, Sajal; Poddar, Madhumita; Saha, Swapan K; Paul, Bidyut K

    2014-09-15

    Modification of the interface by blending of surfactants produces considerable changes in the elastic rigidity of the interface, which in turn affects the physicochemical properties of w/o microemulsions. Hence, it could be possible to tune the thermodynamic properties, microstructures and antimicrobial activity of microemulsions by using ionic/non-ionic mixed surfactants and polar lipophilic oil, which are widely used in biologically relevant systems. The present report was aimed at precise characterization of mixed cetyltrimethylammonium bromide and polyoxyethylene (23) lauryl ether microemulsions stabilized in 1-pentanol (Pn) and isopropyl myristate at different physicochemical conditions by employing phase studies, the dilution method, conductivity, DLS, FTIR (with HOD probing) and (1)H NMR measurements. Further, microbiological activities at different compositions were examined against two bacterial strains Bacillus subtilis and Escherichia coli at 303 K. The formation of mixed surfactant microemulsions was found to be spontaneous at all compositions, whereas it was endothermic at equimolar composition. FTIR and (1)H NMR measurements showed the existence of bulk-like, bound and trapped water molecules in confined environments. Interestingly, composition dependence of both highest and lowest inhibitory effects was observed against the bacterial strains, whereas similar features in spontaneity of microemulsion formation were also evidenced. These results suggested a close relationship between thermodynamic stability and antimicrobial activities. Such studies on polar lipophilic oil derived mixed surfactant microemulsions have not been reported earlier. Copyright © 2014 Elsevier Inc. All rights reserved.

  12. Flow of microemulsion through soil columns contaminated with asphaltic residue; Fluxo de microemulsoes atraves do solo contaminado com residuos asfalticos

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Marcia C.K.; Oliveira, Jose F. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE); Oliveira, Roberto C.G.; Gonzalez, Gazpar [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas

    2004-07-01

    Nowadays, soil contamination with nonaqueous phase liquids (NAPLs) such as petroleum hydrocarbons is a major environmental problem. Significant efforts have been devoted to the development of processes to remediate sites contaminated with NAPLs. Unfortunately, most of the developed processes proved to be inefficient to remove the organic heavy fraction present in the NAPLs. Nevertheless, in our preliminary bench scale tests it was observed that, due to their high solubilization capacity and stability, microemulsions are able to remove organic heavy fractions like asphaltenes and resins, typically present in crude oils. The present work was dimensioned to evaluate, under up-flow condition, the performance of different microemulsions specially designed to remove asphaltenes fractions from soils using a column test set-up. The contaminant residual concentration was quantified by UV spectroscopy and the microemulsion efficiency determined using mass balance. The results showed that the microemulsions tested have a high capacity for removing asphaltenes fractions from contaminated soils. It was also observed that the predominant removal mechanism, solubilization or mobilization, depends essentially on the microemulsion's chemical formulation. Finally it was verified that microemulsion's formulations based on natural solvents compounds are also efficient for removing asphaltic residues. (author)

  13. Microemulsions containing long-chain oil ethyl oleate improve the oral bioavailability of piroxicam by increasing drug solubility and lymphatic transportation simultaneously.

    Science.gov (United States)

    Xing, Qiao; Song, Jia; You, Xiuhua; Xu, Dongling; Wang, Kexin; Song, Jiaqi; Guo, Qin; Li, Pengyu; Wu, Chuanbin; Hu, Haiyan

    2016-09-25

    Drug solubility and lymphatic transport enhancements are two main pathways to improve drug oral bioavailability for microemulsions. However, it is not easy to have both achieved simultaneously because excipients used for improving lymphatic transport were usually insufficient in forming microemulsions and solubilizing drugs. Our research is to explore whether ethyl oleate, an oil effective in developing microemulsions with desired solubilizing capability, could increase bioavailability to a higher extent by enhancing lymphatic transport. As a long-chain oil, ethyl oleate won larger microemulsion area than short-chain tributyrin and medium-chain GTCC. In contrast, long-chain soybean oil failed to prepare microemulsions. The solubility of piroxicam in ethyl oleate microemulsions (ME-C) increased by about 30 times than in water. ME-C also won significantly higher AUC0-t compared with tributyrin microemulsions (ME-A) and GTCC microemulsions (ME-B). Oral bioavailability in ME-C decreased by 38% after lymphatic transport was blocked by cycloheximide, severer than those in ME-A and ME-B (8% and 34%). These results suggest that improving lymphatic transport and solubility simultaneously might be a novel strategy to increase drug oral bioavailability to a higher extent than increasing solubility only. Ethyl oleate is a preferred oil candidate due to its integrated advantages of high solubilizing capability, large microemulsion area and effective lymphatic transport. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Antitumor efficacy of a novel CLA-PTX microemulsion against brain tumors: in vitro and in vivo findings.

    Science.gov (United States)

    Li, Dan; Yang, Ke; Li, Jie-Si; Ke, Xi-Yu; Duan, Yu; Du, Ruo; Song, Ping; Yu, Ke-Fu; Ren, Wei; Huang, Dan; Li, Xing-Huo; Hu, Xin; Zhang, Xuan; Zhang, Qiang

    2012-01-01

    Considering the observations that linoleic acid conjugated with paclitaxel (CLA-PTX) possesses antitumor activity against brain tumors, is able to cross the blood-brain barrier, but has poor water solubility, the purpose of this study was to prepare a novel CLA-PTX microemulsion and evaluate its activity against brain tumors in vitro and in vivo. The in vitro cytotoxicity of a CLA-PTX microemulsion was investigated in C6 glioma cells. The in vivo antitumor activity of the CLA-PTX microemulsion was evaluated in tumor-bearing nude mice and rats. The pharmacokinetics of the CLA-PTX microemulsion were investigated in rats, and its safety was also evaluated in mice. The average droplet size of the CLA-PTX microemulsion was approximately 176.3 ± 0.8 nm and the polydispersity index was 0.294 ± 0.024. In vitro cytotoxicity results showed that the IC(50) of the CLA-PTX microemulsion was 1.61 ± 0.83 μM for a C6 glioma cell line, which was similar to that of free paclitaxel and CLA-PTX solution (P > 0.05). The antitumor activity of the CLA-PTX microemulsion against brain tumors was confirmed in our in vivo C6 glioma tumor-bearing nude mice as well as in a rat model. In contrast, Taxol(®) had almost no significant antitumor effect in C6 glioma tumor-bearing rats, but could markedly inhibit growth of C6 tumors in C6 glioma tumor-bearing nude mice. The pharmacokinetic results indicated that CLA-PTX in solution has a much longer circulation time and produces higher drug plasma concentrations compared with the CLA-PTX microemulsion. The results of the acute toxicity study showed that the LD(50) of CLA-PTX solution was 103.9 mg/kg. In contrast, the CLA-PTX microemulsion was well tolerated in mice when administered at doses up to 200 mg/kg. CLA-PTX microemulsion is a novel formulation with significant antitumor efficacy in the treatment of brain tumors, and is safer than CLA-PTX solution.

  15. Amphiphilic block copolymers as efficiency boosters in microemulsions a SANS investigation of the role of polymers

    CERN Document Server

    Endo, H; Mihailescu, M; Monkenbusch, M; Gompper, G; Richter, D; Jakobs, B; Sottmann, T; Strey, R

    2002-01-01

    The effect of amphiphilic block copolymers on ternary microemulsions (water, oil and non-ionic surfactant) is investigated. Small amounts of PEP-PEO block copolymer lead to a dramatic expansion of the one-phase region where water and oil can be solubilized by the mediation of surfactant molecules. Small-angle neutron-scattering experiments employing a high-precision two-dimensional contrast-variation technique demonstrate that the polymer is distributed uniformly on the surfactant membrane, where it modifies the membrane curvature elasticity. Furthermore, a new approach to determine the bending rigidity of an amphiphilic membrane is proposed, which is precise enough to measure the logarithmic scale dependence of the bending rigidity and its universal prefactor in bicontinuous microemulsions. (orig.)

  16. Predicting for thermodynamic instabilities in water/oil/surfactant microemulsions: A mesoscopic modelling approach

    Energy Technology Data Exchange (ETDEWEB)

    Duvail, Magali, E-mail: magali.duvail@icsm.fr; Zemb, Thomas; Dufrêche, Jean-François [Institut de Chimie Séparative de Marcoule (ICSM), UMR 5257, CEA-CNRS-Université Montpellier 2-ENSCM, Site de Marcoule, Bâtiment 426, BP 17171, F-30207 Bagnols-sur-Cèze Cedex (France); Arleth, Lise [Niels Bohr Institute, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C (Denmark)

    2014-04-28

    The thermodynamics and structural properties of flexible and rigid nonionic water/oil/surfactant microemulsions have been investigated using a two level-cut Gaussian random field method based on the Helfrich formalism. Ternary stability diagrams and scattering spectra have been calculated for different surfactant rigidities and spontaneous curvatures. A more important contribution of the Gaussian elastic constants compared to the bending one is observed on the ternary stability diagrams. Furthermore, influence of the spontaneous curvature of the surfactant points out a displacement of the instability domains which corresponds to the difference between the spontaneous and effective curvatures. We enlighten that a continuous transition from a connected water in oil droplets to a frustrated locally lamellar (oil in water in oil droplets) microstructure is found to occur when increasing the temperature for an oil-rich microemulsion. This continuous transition translated in a shift in the scattering functions, points out that the phase inversion phenomenon occurs by a coalescence of the water droplets.

  17. Neutron spin-echo investigation of the microemulsion dynamics. in bicontinuous lamellar and droplet phases

    CERN Document Server

    Mihailescu, M; Endo, H; Allgaier, J; Gompper, G; Stellbrink, J; Richter, D; Jakobs, B; Sottmann, T; Faragó, B

    2002-01-01

    Using neutron spin-echo (NSE) spectroscopy in combination with dynamic light scattering (DLS), we performed an extensive investigation of the bicontinuous phase in ternary water-surfactant-oil microemulsions, with extension to lamellar and droplet phases. The dynamical behavior of surfactant monolayers of decyl-polyglycol-ether (C sub 1 sub 0 E sub 4) molecules, or mixtures of surfactant with long amphiphilic block-copolymers of type poly-ethylene propylene/poly-ethylene oxide (PEP-PEO) was studied, under comparable conditions. The investigation techniques provide access to different length scales relative to the characteristic periodicity length of the microemulsion structure. Information on the elastic bending modulus is obtained from the local scale dynamics in view of existing theoretical descriptions and is found to be in accordance with small angle neutron scattering (SANS) studies. Evidence for the modified elastic properties and additional interaction of the amphiphilic layers due to the polymer is mo...

  18. Superswollen microemulsions stabilized by shear and trapped by a temperature quench.

    Science.gov (United States)

    Roger, Kevin; Olsson, Ulf; Zackrisson-Oskolkova, Malin; Lindner, Peter; Cabane, Bernard

    2011-09-06

    We studied the solubilization of oil in the C(16)E(8)/hexadecane/H(2)O system. Close to the phase inversion temperature (PIT), the system, at equilibrium, can form either homogeneous states (i.e., microemulsions) at high surfactant concentrations or three-phase states at lower concentrations. We show that, under gentle shear, at a line we named the clearing boundary (CB), located a few degrees below the PIT, the system is homogeneous regardless of the surfactant concentration. We relate this shift of the microemulsion boundary to shear-induced disruption of the asymmetric bicontinuous structure. Although this state quickly relaxes to equilibrium when shear is stopped, we show that it is still possible to trap it into a metastable state through a temperature quench. This method is the sub-PIT emulsification that we described in a previous work (Roger Langmuir 2010, 26, 3860-3867). © 2011 American Chemical Society

  19. AOT-microemulsions-based formation and evolution of PbWO$_{4}$ crystals

    CERN Document Server

    Chen, D; Tang Kai Bin; Liang Zhen Hua; Zheng Hua Gui

    2004-01-01

    Anionic surfactant-AOT-microemulsions-assisted formation and evolution of PbWO//4 nanostructures with bundles rodlike, ellipsoidlike, and spherelike prepared at different media conditions were studied by powder X-ray diffraction pattern, field emission scanning electron microscopy, and transmission electron microscopy. The possible mechanisms for the formation of PbWO//4 samples in series of microemulsion systems were discussed. Various comparison experiments show that several experimental parameters, such as the AOT concentration, the water content, and reaction temperature play important roles in the morphological control of PbWO//4 nanostructures. Room-temperature photoluminescence of PbWO//4 samples with different morphologies has also been investigated and the results reveal that all these samples showed similar features with emissions at 480 similar to 510 nm but different luminescence intensity. 40 Refs.

  20. Slow relaxation mode in concentrated oil-in-water microemulsions consisting of repulsive droplets

    Science.gov (United States)

    Hattori, Y.; Ushiki, H.; Courbin, L.; Panizza, P.

    2007-02-01

    The present contribution reports on the observation of two diffusive relaxation modes in a concentrated microemulsion made of repulsive droplets. These two modes can be interpreted in the frame of Weissman’s and Pusey’s theoretical pioneering works. The fast mode is associated to the collective diffusion of droplets whereas the slow one corresponds to the relaxation of droplet concentration fluctuations associated with composition and/or size. We show that (i) repulsive interactions considerably slow down the latter and (ii) a generalized Stokes Einstein relationship between its coefficient of diffusion and the Newtonian viscosity of the solutions, similar to the Walden’s rule for electrolytes, holds for concentrated microemulsion systems made of repulsive droplets.

  1. APPLICATION OF AN EXPERIMENTAL METHODOLOGY IN THE OPTIMIZATION OF A TUNGSTEN CONCENTRATION PROCESS BY MICROEMULSIONS

    Directory of Open Access Journals (Sweden)

    A.C.S. RAMOS

    1997-06-01

    Full Text Available Abstract - In this work, we applied an experimental planning methodology in order to correlate the necessary amounts with the description of the a tungsten extraction process by microemulsions. The result is a mathematical modelling carried out using the Sheffe Net method, where the mixtures concentration values are represented inside an equilateral triangle. The tungsten concentration process occurs in two stages: extraction and reextraction. The extraction stage was determined by monitoring: phase relative volume (Vr, extraction percentage (%E and tungsten concentration in the microemulsion phase (Ctm e. The reextraction phase was determined by monitoring: reextraction percentage (%Re and tungsten concentration in the aqueous phase (Ctaq. Finally, we obtained equations that relate the extraction / reextraction properties to the composition of specific points inside the extraction region, obeying the error limits specified for the acceptance of each parameter. The results were evaluated through the construction of isoresponse diagrams and correlation graphics between experimental values and those obtained through use of equations.

  2. Effect of AOT Microemulsion Composition on the Hydrodynamic Diameter and Electrophoretic Mobility of Titanium Oxide Nanoparticles

    Science.gov (United States)

    Shaparenko, N. O.; Beketova, D. I.; Demidova, M. G.; Bulavchenko, A. I.

    2018-05-01

    The hydrodynamic diameter and electrophoretic mobility of titania nanoparticles in AOT microemulsions are studied depending on their water content (from 0 to 1.5 vol %), chloroform content in n-decane-chloroform mixture (from 0 to 30 vol %) and temperature (from 0 to 60°C). Considerable changes in diameter (from 20 to 400 nm) are detected upon adding water to the microemulsion. The electrophoretic mobility grows by 2-3 times upon adding chloroform, or as the temperature falls. The observed features allow us to halve the time of electrophoretic concentration for 140 nm TiO2 nanoparticles, and to concentrate 14 nm nanoparticles that do not exhibit electrophoretic mobility in the absence of chloroform.

  3. Quality by Design approach for an in situ gelling microemulsion of Lorazepam via intranasal route.

    Science.gov (United States)

    Shah, Vidhi; Sharma, Mukesh; Pandya, Radhika; Parikh, Rajesh K; Bharatiya, Bhavesh; Shukla, Atindra; Tsai, Hsieh-Chih

    2017-06-01

    The present study illustrates the application of the concept of Quality by Design for development, optimization and evaluation of Lorazepam loaded microemulsion containing ion responsive In situ gelator gellan gum and carbopol 934. A novel approach involving interactions between surfactant and polymer was employed to achieve controlled drug release and reduced mucociliary clearance. Microemulsion formulated using preliminary solubility study and pseudo ternary phase diagrams showed significantly improved solubilization capacity of Lorazepam with 54.31±6.07nm droplets size. The effect of oil to surfactant/cosurfactant ratio and concentration of gelling agent on the drug release and viscosity of microemulsion gel (MEG) was evaluated using a 3 2 full factorial design. The gel of optimized formulation (MEG 1 ) showed a drug release up to 6h of 97.32±1.35% of total drug loaded. The change in shear-dependent viscosity for different formulations on interaction with Simulated Nasal Fluid depicts the crucial role of surfactant-polymer interactions on the gelation properties along with calcium ions binding on the polymer chains. It is proposed that the surfactant-polymer interactions in the form of a stoichiometric hydrogen bonding between oxyethylene and carboxylic groups of the polymers used, provides exceptional ME stability and adhesion properties. Compared with the marketed formulation, optimized MEG showed improved pharmacodynamic activity. Ex vivo diffusion studies revealed significantly higher release for MEG compared to microemulsion and drug solution. MEG showed higher flux and permeation across goat nasal mucosa. According to the study, it could be concluded that formulation would successfully provide the rapid onset of action, and decrease the mucociliary clearance due to formation of in situ gelling mucoadhesive system. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Microemulsion Formulation of Carbendazim and Its In Vitro Antifungal Activities Evaluation

    Science.gov (United States)

    Leng, Pengfei; Zhang, Zhiming; Li, Qian; Zhao, Maojun; Pan, Guangtang

    2014-01-01

    The fungus Rhizoctonia solani Kuhn is a widespread and destructive plant pathogen with a very broad host range. Although various pathogens, including R. solani, have been traditionally controlled using chemical pesticides, their use faces drawbacks such as environmental pollution, development of pesticide resistance, and other negative effects. Carbendazim is a well-known antifungal agent capable of controlling a broad range of plant diseases, but its use is hampered by its poor aqueous solubility. In this study, we describe an environmentally friendly pharmaceutical microemulsion system using carbendazim as the active ingredient, chloroform and acetic acid as solvents, and the surfactants HSH and 0204 as emulsifiers. This system increased the solubility of carbendazim to 30 g/L. The optimal microemulsion formulation was determined based on a pseudo-ternary phase diagram; its physicochemical characteristics were also tested. The cloud point was greater than 90°C and it was resistant to freezing down to −18°C, both of which are improvements over the temperature range in which pure carbendazim can be used. This microemulsion meets the standard for pesticide microemulsions and demonstrated better activity against R. solani AG1-IA, relative to an aqueous solution of pure carbendazim (0.2 g/L). The mechanism of activity was reflected in the inhibition of against R. solani AG1-IA including mycelium growth, and sclerotia formation and germination were significantly better than that of 0.2 g/L carbendazim water solution according to the results of t-test done by SPSS 19. PMID:25310219

  5. In-site synthesis of monodisperse, oleylamine-capped Ag nanoparticles through microemulsion approach

    Science.gov (United States)

    Chen, Shun; Ju, Yanyun; Guo, Yi; Xiong, Chuanxi; Dong, Lijie

    2017-03-01

    Ag NPs were in-site synthesized through microemulsion method by reducing silver acetate with oleylamine-mediated at 70 °C with highly monodisperse and narrow size from 10 to 20 nm. The synthesis of Ag NPs was aided by oleylamine and the role of oleylamine was researched. This in-site synthesis approach to Ag NPs was reproducibility and high yield more than 80% with stable store about 6 months.

  6. Utilization of Microemulsions from Rhinacanthus nasutus (L.) Kurz to Improve Carotenoid Bioavailability

    Science.gov (United States)

    Ho, Nai-Hsing; Inbaraj, Baskaran Stephen; Chen, Bing-Huei

    2016-01-01

    Carotenoids have been known to reduce the risk of several diseases including cancer and cardiovascular. However, carotenoids are unstable and susceptible to degradation. Rhinacanthus nasutus (L.) Kurz (R. nasutus), a Chinese medicinal herb rich in carotenoids, was reported to possess vital biological activities such as anti-cancer. This study intends to isolate carotenoids from R. nasutus by column chromatography, identify and quantify by HPLC-MS, and prepare carotenoid microemulsions for determination of absolute bioavailability in rats. Initially, carotenoid fraction was isolated using 250 mL ethyl acetate poured into an open-column packed with magnesium oxide-diatomaceous earth (1:3, w/w). Fourteen carotenoids including internal standard β-apo-8′-carotenal were resolved within 62 min by a YMC C30 column and gradient mobile phase of methanol-acetonitrile-water (82:14:4, v/v/v) and methylene chloride. Highly stable carotenoid microemulsions were prepared using a mixture of CapryolTM90, Transcutol®HP, Tween 80 and deionized water, with the mean particle being 10.4 nm for oral administration and 10.7 nm for intravenous injection. Pharmacokinetic study revealed that the absolute bioavailability of carotenoids in microemulsions and dispersion was 0.45% and 0.11%, respectively, while a much higher value of 6.25% and 1.57% were shown for lutein, demonstrating 4-fold enhancement in bioavailability upon incorporation of R. nasutus carotenoids into a microemulsion system. PMID:27150134

  7. In-site synthesis of monodisperse, oleylamine-capped Ag nanoparticles through microemulsion approach

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shun; Ju, Yanyun [Wuhan University of Technology, School of Materials Science and Engineering (China); Guo, Yi [Wuhan University of Technology, Center for Materials Research and Analysis (China); Xiong, Chuanxi; Dong, Lijie, E-mail: dong@whut.edu.cn [Wuhan University of Technology, School of Materials Science and Engineering (China)

    2017-03-15

    Ag NPs were in-site synthesized through microemulsion method by reducing silver acetate with oleylamine-mediated at 70 °C with highly monodisperse and narrow size from 10 to 20 nm. The synthesis of Ag NPs was aided by oleylamine and the role of oleylamine was researched. This in-site synthesis approach to Ag NPs was reproducibility and high yield more than 80% with stable store about 6 months.

  8. Microemulsion Transdermal Formulation for Simultaneous Delivery of Valsartan and Nifedipine: Formulation by Design.

    Science.gov (United States)

    Sood, Jatin; Sapra, Bharti; Tiwary, Ashok K

    2017-08-01

    The objective of the study was to optimize the proportion of different components for formulating oil in water microemulsion formulation meant for simultaneous transdermal delivery of two poorly soluble antihypertensive drugs. Surface response methodology of Box-Behnken design was utilized to evaluate the effect of two oils (Captex 500 - x1 and Capmul MCM - x2) and surfactant (Acrysol EL135 - x3) on response y1 (particle size), y2 (solubility of valsartan), and y3 (solubility of nifedipine). The important factors which significantly affected the responses were identified and validated using ANOVA. The model was diagnosed using normal plot of residuals and Box-Cox plot. The design revealed an inverse correlation between particle size and concentration of Capmul MCM and Acrysol EL 135. However, an increase in concentration of Captex 500 led to an increase in particle size of microemulsion. Solubility of valsartan decreased while that of nifedipine increased with increase in concentration of Captex 500. Capmul MCM played a significant role in increasing the solubility of valsartan. The effect of Acrysol EL 135 on solubility of both drugs, although significant, was only marginal as compared to that of Captex 500 and Capmul MCM. The optimized microemulsion was able to provide an enhancement ratio of 27.21 and 63.57-fold for valsartan and nifedipine, respectively, with respect to drug dispersion in aqueous surfactant system when evaluated for permeation studies. The current studies candidly suggest the scope of microemulsion systems for solubilizing as well as promoting the transport of both drugs across rat skin at an enhanced permeation rate.

  9. The development of Cutina lipogels and gel microemulsion for topical administration of fluconazole

    OpenAIRE

    Ellaithy, H. M.; El-Shaboury, K. M. F.

    2002-01-01

    The influence of the vehicle on the release and permeation of fluconazole, a topical antifungal drug dissolved in Jojoba oil was evaluated. Series of Cutina lipogels (Cutina CPA [cetyl palmitate], CBS [mixture of glyceryl stearate, cetearyl alcohol, cetyl palmitate, and cocoglycerides], MD [glyceryl stearate], and GMS [glyceryl monostearate]) in different concentrations as well as gel microemulsion were prepared. In-vitro drug release in Sorensens citrate buffer (pH 5.5) and permeation throug...

  10. Application of positron annihilation techniques to the study of micels and microemulsions

    International Nuclear Information System (INIS)

    Olea C, O.

    1981-01-01

    The molecular auto-association mechanisms in sodium-oleate-alcohol-alkane-water systems were studied, applying positron and positronium annihilation techniques. The effects of the different component structures of these systems and of their concentrations on the swelled micel formation process which eventually produce microemulsions, were also investigated. The influences studied were: a) co-surfactant (alcohol) hydrocarbon chain lengths, b) alkane (oil) hydrocarbon chain lengths, c) surfactant concentrations, and d) surfactant double link alkylic chains. (author)

  11. Microemulsion-based oxyresveratrol for topical treatment of herpes simplex virus (HSV) infection: physicochemical properties and efficacy in cutaneous HSV-1 infection in mice.

    Science.gov (United States)

    Sasivimolphan, Pattaraporn; Lipipun, Vimolmas; Ritthidej, Garnpimol; Chitphet, Khanidtha; Yoshida, Yoshihiro; Daikoku, Tohru; Sritularak, Boonchoo; Likhitwitayawuid, Kittisak; Pramyothin, Pornpen; Hattori, Masao; Shiraki, Kimiyasu

    2012-12-01

    The physicochemical properties of the optimized microemulsion and the permeating ability of oxyresveratrol in microemulsion were evaluated, and the efficacy of oxyresveratrol microemulsion in cutaneous herpes simplex virus type 1 (HSV-1) infection in mice was examined. The optimized microemulsion was composed of 10% w/w of isopropyl myristate, 35% w/w of Tween 80, 35% w/w of isopropyl alcohol, and 20% w/w of water. The mean particle diameter was 9.67 ± 0.58 nm, and the solubility of oxyresveratrol in the microemulsion was 196.34 ± 0.80 mg/ml. After accelerated and long-term stability testing, the microemulsion base and oxyresveratrol-loaded microemulsion were stable. The cumulative amount of oxyresveratrol permeating through shed snake skin from microemulsion at 6 h was 93.04 times compared to that of oxyresveratrol from Vaseline, determined at 20% w/w concentration. In cutaneous HSV-1 infection in mice, oxyresveratrol microemulsion at 20%, 25%, and 30% w/w, topically applied five times daily for 7 days after infection, was significantly effective in delaying the development of skin lesions and protecting from death (p microemulsion at 25% and 30% w/w was significantly more effective than that of 30% w/w of oxyresveratrol in Vaseline (p  0.05). These results demonstrated that topical oxyresveratrol microemulsion at 20-30% w/w was suitable for cutaneous HSV-1 mouse infection.

  12. Intravenous microemulsion of docetaxel containing an anti-tumor synergistic ingredient (Brucea javanica oil): formulation and pharmacokinetics

    Science.gov (United States)

    Ma, Shilin; Chen, Fen; Ye, Xiaohui; Dong, Yingjie; Xue, Yingna; Xu, Heming; Zhang, Wenji; Song, Shuangshuang; Ai, Li; Zhang, Naixian; Pan, Weisan

    2013-01-01

    The purpose of this study was to develop a docetaxel microemulsion containing an anti-tumor synergistic ingredient (Brucea javanica oil) and to investigate the characteristics of the microemulsion. Brucea javanica oil contains oleic acid and linoleic acids that have been shown by animal and human studies to inhibit tumor formation. The microemulsion containing Brucea javanica oil, medium-chain triglyceride, soybean lecithin, Solutol®HS 15, PEG 400, and water was developed for docetaxel intravenous administration. A formulation with higher drug content, lower viscosity, and smaller particle size was developed. The droplet size distribution of the dispersed phase of the optimized microemulsion was 13.5 nm, determined using a dynamic light scattering technique. The small droplet size enabled the microemulsion droplets to escape from uptake and phagocytosis by the reticuloendothelial system and increased the circulation time of the drug. The zeta potential was −41.3 mV. The optimized microemulsion was pale yellow, transparent, and non-opalescent in appearance. The value of the combination index was 0.58, showing that there was a synergistic effect when docetaxel was combined with Brucea javanica oil. After a single intravenous infusion dose (10 mg/kg) in male Sprague Dawley rats, the area under the curve of the microemulsion was higher and the half-time was longer compared with that of docetaxel solution alone, and showed superior pharmacokinetic characteristics. These results indicate that this preparation of docetaxel in emulsion is likely to provide an excellent prospect for clinical tumor treatment. PMID:24179332

  13. Synthesis and Characterization of InS Nanorods in Sucrose Ester Water-in-Oil Microemulsion

    Directory of Open Access Journals (Sweden)

    N. M. Huang

    2011-01-01

    Full Text Available We report the synthesis of In2S3 nanorods in a nonionic sugar-based water-in-oil (w/o microemulsion system using food grade sucrose ester as biosurfactant. In2S3 was formed by mixing indium (III chloride and thioacetamide in the water core of the microemulsion system. The as-prepared yellowish In2S3 was characterized by X-ray diffractometry (XRD, UV-visible absorption spectroscopy (UV-Vis, transmission electron microscopy (TEM, and Fourier transform infrared spectroscopy (FTIR. Formation of spherical or rod-like In2S3 nanomaterials was dependent on reaction time. Rod-like In2S3, arranged in bundles, was formed only after 2 days of reaction time. Upon longer aging time, a mixture of rod-like and spherical In2S3 was formed. A plausible formation mechanism of the In2S3 nanorods in the sucrose ester microemulsion was postulated. The diameter of the In2S3 nanorods was found to be very small, which is 8.97±2.36 nm with aspect ratio of 20 : 1 (length : diameter.

  14. Preparation and Evaluation of Tretinoin Microemulsion Based on Pseudo-Ternary Phase Diagram

    Directory of Open Access Journals (Sweden)

    Fatemeh Leis

    2012-06-01

    Full Text Available Purpose: The aim of the present research was to formulate a transparent microemolsion as a topical delivery system for tretinoin for the treatment of acne. Methods: Microemulsion formulations prepared by mixing appropriate amount of surfactant including Tween 80 and Labrasol, co-surfactant such as propylene glycol (PG and oil phase including isopropyl myristate – transcutol P (10:1 ratio. The prepared microemolsions were evaluated regarding their particle size, zeta potential, conductivity, stability, viscosity, differential scanning calorimetry (DSC, scanning electron microscopy (SEM, refractory index (RI and pH. Results: The results showed that maximum oil was incorporated in microemolsion system that was contained surfactant to co-surfactant ratio (Km of 4:1. The mean droplets size range of microemulsion formulation were in the range of 14.1 to 36.5 nm and its refractory index (RI and pH were 1.46 and 6.1, respectively. Viscosity range was 200-350 cps. Drug release profile showed 49% of the drug released in the first 8 hours of experiment belong to ME-7. Also, Hexagonal and cubic structures were seen in the SEM photograph of the microemulsions. Conclusion: physicochemical properties and in vitro release were dependent upon the contents of S/C, water and, oil percentage in formulations.Also, ME-7 may be preferable for topical tretinoin formulation.

  15. Water solubilization capacity of pharmaceutical microemulsions based on Peceol®, lecithin and ethanol.

    Science.gov (United States)

    Mouri, Abdelkader; Diat, Olivier; Lerner, Dan Alain; El Ghzaoui, Abdeslam; Ajovalasit, Alessia; Dorandeu, Christophe; Maurel, Jean-Claude; Devoisselle, Jean-Marie; Legrand, Philippe

    2014-11-20

    Biocompatible microemulsions composed of Peceol(®), lecithin, ethanol and water developed for encapsulation of hydrophilic drugs were investigated. The binary mixture Peceol(®)/ethanol was studied first. It was shown that the addition of ethanol to pure Peceol(®) has a significant fluidifying and disordering effect on the Peceol(®) supramolecular structure with an enhancement in water solubilization. The water solubilization capacity was improved by adding lecithin as a third component. It was then demonstrated that the ethanol/lecithin weight ratio played an important role in determining the optimal composition in term of water solubilization efficiency, a necessary property for a nutraceutical or pharmaceutical application. The optimal ethanol/lecithin weight ratio in the Peceol(®) rich region was found to be 40/60. Combination different techniques such as SAXS, fluorimetry, rheology and conductivity, we analyzed the water uptake within the microemulsion taking into account the partitioning of ethanol between polar and apolar domains. This ethanol distribution quantified along a water dilution line has a major effect on microemulsion properties. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Small-angle light scattering studies of dense AOT-water-decane microemulsions

    International Nuclear Information System (INIS)

    Micali, N.; Trusso, S.; Mallamace, F.; Chen, S.H.

    1996-01-01

    It is performed extensive studies of a three-component microemulsion system composed of AOT-water-decane using small-angle light scattering (SALS). The small-angle scattering intensities are measured in the angular interval 0.001-0.1 radians, corresponding to a Bragg wave number range of 0.14 μm -1 -1 . The measurements were made by changing temperature and volume fraction φ of the dispersed phase in the range 0.65< φ < 0.75. All samples have a fixed water-to-AOT molar ratio, w [water[/[AOT[ = 40.8, in order to keep the same average droplet size in the stable one-phase region. With the SALS technique it is observed all the phase boundaries of a very complex phase diagram with a percolation line and many structural organizations within it. It is observed at the percolation transition threshold, a scaling behavior of the intensity data. In addition it is described in detail a structural transition from a droplet microemulsion to a bi continuous one a suggested by a recent small-angle neutron scattering experiment. From the data analysis it is show that both the percolation phenomenon and this novel structural transition are described from a large-scale aggregation between microemulsion droplets

  17. Kinetic model for reactivity in quaternary water-in-oil microemulsions.

    Science.gov (United States)

    García-Río, Luis; Hervella, Pablo

    2006-11-06

    A study was carried out on the nitrosation of piperazine (PIP) and N-methylbenzylamine (MeBzAm) by N-methyl-N-nitroso-p-toluenesulfonamide (MNTS) in quaternary microemulsions of tetradecyltrimethylammonium bromide (TTABr)/isooctane/alcohol/water, varying the nature and the concentration of the following alcohols: 1-pentanol, 1-hexanol, 1-heptanol, 1-octanol and 1-decanol keeping the [1-alcohol]/[TTABr] = 4 relationship constant. In addition a study was carried out on the influence of the alcohol concentration, working with molar relationships [1-hexanol]/[TTABr]=3, 4 and 5. On the basis of the molar volumes of the alcohol and surfactant and the concentration of alcohol at the interface it was possible to calculate the change in its volume with as varying compositions of the microemulsion. In order to interpret the experimental results a kinetic model was devised which takes into account the distribution of the reactants between the different pseudophases and the change in the volume of the interface. The rate constants at the interface of the microemulsion are lower than in pure water and are independent of the nature of the alcohol used as a cosurfactant and the molar relationship [alcohol]/[TTABr]. This independence indicates that the main role of the cosurfactant is to increase the volume of the interface with the consequent dilution of the reactants.

  18. Determination of drug lipophilicity by phosphatidylcholine-modified microemulsion high-performance liquid chromatography.

    Science.gov (United States)

    Xuan, Xueyi; Xu, Liyuan; Li, Liangxing; Gao, Chongkai; Li, Ning

    2015-07-25

    A new biomembrane-mimetic liquid chromatographic method using a C8 stationary phase and phosphatidylcholine-modified (PC-modified) microemulsion mobile phase was used to estimate unionized and ionized drugs lipophilicity expressed as an n-octanol/water partition coefficient (logP and logD). The introduction of PC into sodium dodecyl sulfate (SDS) microemulsion yielded a good correlation between logk and logD (R(2)=0.8). The optimal composition of the PC-modified microemulsion liquid chromatography (PC-modified MELC) mobile phase was 0.2% PC-3.0% SDS-6.0% n-butanol-0.8% ethyl acetate-90.0% water (pH 7.0) for neutral and ionized molecules. The interactions between the analytes and system described by this chromatographic method is more similar to biological membrane than the n-octanol/water partition system. The result in this paper suggests that PC-modified MELC can serve as a possible alternative to the shake-flask method for high-throughput unionized and ionized drugs lipophilicity determination and simulation of biological processes. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Antimicrobial edible coatings and films from micro-emulsions and their food applications.

    Science.gov (United States)

    Guo, Mingming; Yadav, Madhav P; Jin, Tony Z

    2017-12-18

    This study focused on the use of antimicrobial edible coatings and films from micro-emulsions to reduce populations of foodborne pathogens in foods. Corn-Bio-fiber gum (C-BFG) was used as an emulsifier with chitosan. Allyl isothiocyanate (AIT) and lauric arginate ester (LAE) served as antimicrobials. Micro-emulsions were obtained from a solution consisting of 1% chitosan, 0.5% C-BFG, and 1-4% AIT or LAE which was subject to high pressure homogenization (HPH) processing at 138MPa for 3cycles. Coatings and films produced from the micro-emulsions had micro-pores with sizes ranging from 100 to 300nm and micro-channels that hold antimicrobials effectively and facilitate the release of antimicrobials from the center to the surface of the films or coatings, thus enhancing their antimicrobial efficacy. The coatings and films with 1% AIT reduced populations of Listeria innocua by over 5, 2, and 3 log CFU in culture medium (Tryptic soy broth, TSB), ready-to-eat meat, and strawberries, respectively. The coatings and films with 1% LAE reduced populations of Escherichia coli O157:H7 and Salmonella spp. by over 5 and 2 log CFU in TSB and strawberries, respectively. This study provides an innovative approach for the development of effective antimicrobial materials to reduce food borne pathogenic contaminants on ready-to-eat meat, strawberries, or other food. Published by Elsevier B.V.

  20. Effect of water content on partial ternary phase diagram water-in-diesel microemulsion fuel

    Science.gov (United States)

    Mukayat, Hastinatun; Badri, Khairiah Haji; Raman, Ismail Ab.; Ramli, Suria

    2014-09-01

    Introduction of water in the fuel gave a significant effect to the reduction of pollutant such as NOx emission. In this work, water/diesel microemulsion fuels were prepared using compositional method by mixing water and diesel in the presence of non-ionic surfactant and co-surfactant. The effects of water composition on the partial ternary phase diagram were studied at 5%, 10%, 15% and 20% (w/w). The physical stability of the microemulsion was investigated at 45°C over a period of one month. The optimum formulae obtained were diesel/T80/1-penthanol/water 60:20:15:5 wt% (System 1), 55:20:15:10 wt% (System 2), 50:20:15:15 wt% (System 3) and 45:20:15:20 wt% (System 4). Physicochemical characterizations of optimum formulae were studied. The results showed that water content has a significant effect to the formation of microemulsion, its stability, droplet size and viscosity.

  1. Rapid determination of water- and fat-soluble vitamins with microemulsion electrokinetic chromatography.

    Science.gov (United States)

    Yin, Changna; Cao, Yuhua; Ding, Shaodong; Wang, Yun

    2008-06-06

    A rapid, reliable and reproducible method based on microemulsion electrokinetic chromatography (MEEKC) for simultaneous determination of 13 kinds of water- and fat-soluble vitamins has been developed in this work. A novel microemulsion system consisting of 1.2% (w/w) sodium lauryl sulphate (SDS), 21% (v/v) 1-butanol, 18% (v/v) acetonitrile, 0.8% (w/w) n-hexane, 20mM borax buffer (pH 8.7) was applied to improve selectivity and efficiency, as well as shorten analysis time. The composition of microemulsion used as the MEEKC running buffer was investigated thoroughly to obtain stable separation medium, as well as the optimum determination conditions. Acetonitrile as the organic solvent modifier, pH of the running buffer and 1-butanol as the co-surfactant played the most important roles for the separation of the fat-soluble vitamins, water-soluble vitamins and stabilization of system, respectively. The 13 water- and fat-soluble vitamins were baseline separated within 30 min. The system was applied to determine water- and fat-soluble vitamins in commercial multivitamin pharmaceutical formulation, good accuracy and precision were obtained with recoveries between 97% and 105%, relative standard derivations (RSDs) less than 1.8% except vitamin C, and acceptable quantitative results corresponding to label claim.

  2. Hydrolysis of triolein in phospholipid vesicles and microemulsions by a purified rat liver acid lipase.

    Science.gov (United States)

    Burrier, R E; Brecher, P

    1983-10-10

    An acid lipase was purified from rat liver lysosomes. Lipase purification involved affinity chromatography, gel filtration, and stabilization of the purified preparation using ethylene glycol and Triton X-100. A molecular weight of 67,000-69,000 was determined independently using density gradient centrifugation, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and gel filtration. To study enzyme action, model substrates were prepared by incorporating radiolabeled triolein into either unilamellar vesicles or microemulsions. Substrates were prepared by cosonicating aqueous dispersions of lecithin and triolein. Formation of vesicles or emulsions depended on the relative amount of each lipid and on sonication conditions. Vesicles were prepared at molar ratios between 70:1 and 26:1 (lecithin:triolein) and the microemulsion preparation at a molar ratio of 1:1. The substrate particles were of similar size (220-250 A) as determined by Bio-Gel A-15m chromatography. Hydrolysis of triolein contained in vesicles or emulsions was similar with respect to pH, temperature, and reaction products. Kinetic studies on vesicles with increasing triolein content showed progressively greater Vmax values (0-0.6 mumol/min/mg), and Vmax for the emulsion was 3.1 mumol/min/mg. Addition of human very low or low density lipoprotein produced a dose-dependent inhibition with both substrates. The results show that synthetically prepared microemulsions are stable and effective substrates for the acid lipase and indicate that surface-oriented triolein is hydrolyzed in both preparations.

  3. Delivery systems for biopharmaceuticals. Part II: Liposomes, Micelles, Microemulsions and Dendrimers.

    Science.gov (United States)

    Silva, Ana C; Lopes, Carla M; Lobo, José M S; Amaral, Maria H

    2015-01-01

    Biopharmaceuticals are a generation of drugs that include peptides, proteins, nucleic acids and cell products. According to their particular molecular characteristics (e.g. high molecular size, susceptibility to enzymatic activity), these products present some limitations for administration and usually parenteral routes are the only option. To avoid these limitations, different colloidal carriers (e.g. liposomes, micelles, microemulsions and dendrimers) have been proposed to improve biopharmaceuticals delivery. Liposomes are promising drug delivery systems, despite some limitations have been reported (e.g. in vivo failure, poor long-term stability and low transfection efficiency), and only a limited number of formulations have reached the market. Micelles and microemulsions require more studies to exclude some of the observed drawbacks and guarantee their potential for use in clinic. According to their peculiar structures, dendrimers have been showing good results for nucleic acids delivery and a great development of these systems during next years is expected. This is the Part II of two review articles, which provides the state of the art of biopharmaceuticals delivery systems. Part II deals with liposomes, micelles, microemulsions and dendrimers.

  4. Solubilization of tea seed oil in a food-grade water-dilutable microemulsion.

    Directory of Open Access Journals (Sweden)

    Lingli Deng

    Full Text Available Food-grade microemulsions containing oleic acid, ethanol, Tween 20, and water were formulated as a carrier system for tea seed oil (Camellia oleifera Abel.. The effect of ethanol on the phase behavior of the microemulsion system was clearly reflected in pseudo-ternary diagrams. The solubilization capacity and solubilization efficiency of tea seed oil dispersions were measured along the dilution line at a 70/30 surfactant/oil mass ratio with Tween 20 as the surfactant and oleic acid and ethanol (1:3, w/w as the oil phase. The dispersed phase of the microemulsion (1.5% weight ratio of tea seed oil to the total amount of oil, surfactant, and tea seed oil could be fully diluted with water without phase separation. Differential scanning calorimetry and viscosity measurements indicated that both the carrier and solubilized systems underwent a similar microstructure transition upon dilution. The dispersion phases gradually inverted from the water-in-oil phase ( 45% water along the dilution line.

  5. Cage-like effect in Au-Pt nanoparticle synthesis in microemulsions: a simulation study.

    Science.gov (United States)

    Tojo, C; de Dios, M; Buceta, D; López-Quintela, M A

    2014-09-28

    The different distributions of metals in bimetallic nanoparticles synthesized in microemulsions were studied by computer simulation. The simulations demonstrated that if the difference between the reduction potentials of both metals is about 0.15-0.3 V, the compartmentalization of the reaction media causes the accumulation of slower reduction reactants in the microemulsions droplets, which favours the chemical reaction like a cage effect: increasing the local concentration of the slower reduction metal salt gives rise to a faster reduction, so the differences in reduction rates of both metals are attenuated. A more coincidental reduction of both metals deeply affects the nanoparticle structure, causing a better mixed alloy. This effect will be more pronounced when the concentration is higher and the intermicellar exchange rate is faster. This means that for any fixed microemulsion the nanoparticle structure can be modified by changing the reactant concentration: the core can be enriched in the faster reduction metal by lower concentrations, and the shell can be enriched in the slower metal by higher concentrations. Based on these observations, this study suggests a route to help experimentalists better create nanoparticles with a pre-defined structure.

  6. Mixture experiment methods in the development and optimization of microemulsion formulations.

    Science.gov (United States)

    Furlanetto, S; Cirri, M; Piepel, G; Mennini, N; Mura, P

    2011-06-25

    Microemulsion formulations represent an interesting delivery vehicle for lipophilic drugs, allowing for improving their solubility and dissolution properties. This work developed effective microemulsion formulations using glyburide (a very poorly-water-soluble hypoglycaemic agent) as a model drug. First, the area of stable microemulsion (ME) formations was identified using a new approach based on mixture experiment methods. A 13-run mixture design was carried out in an experimental region defined by constraints on three components: aqueous, oil and surfactant/cosurfactant. The transmittance percentage (at 550 nm) of ME formulations (indicative of their transparency and thus of their stability) was chosen as the response variable. The results obtained using the mixture experiment approach corresponded well with those obtained using the traditional approach based on pseudo-ternary phase diagrams. However, the mixture experiment approach required far less experimental effort than the traditional approach. A subsequent 13-run mixture experiment, in the region of stable MEs, was then performed to identify the optimal formulation (i.e., having the best glyburide dissolution properties). Percent drug dissolved and dissolution efficiency were selected as the responses to be maximized. The ME formulation optimized via the mixture experiment approach consisted of 78% surfactant/cosurfacant (a mixture of Tween 20 and Transcutol, 1:1, v/v), 5% oil (Labrafac Hydro) and 17% aqueous phase (water). The stable region of MEs was identified using mixture experiment methods for the first time. Copyright © 2011 Elsevier B.V. All rights reserved.

  7. Clotrimazole microemulsion and microemulsion-based gel: evaluation of buccal drug delivery and irritancy using chick chorioallantoic membrane as the model.

    Science.gov (United States)

    Kaewbanjong, Jarika; Wan Sia Heng, Paul; Boonme, Prapaporn

    2017-12-01

    To investigate the efficacy of clotrimazole microemulsion (CTZ-ME) and its gel form, clotrimazole microemulsion-based gel (CTZ-MBG), for the treatment of oral candidiasis. CTZ-ME and CTZ-MBG were characterized for droplet size and texture, respectively. The ex-vivo permeation study and irritancy assessment of CTZ-ME and CTZ-MBG were performed using chick chorioallantoic membrane (CAM) as the model. Antifungal activity against Candida albicans ATCC 10 231 of CTZ-ME and CTZ-MBG was determined by agar diffusion method compared to the blank counterparts. CTZ-ME contained nano-sized droplets and CTZ-MBG had acceptable firmness and spreadability. CTZ-ME exhibited faster CAM permeation of the drug and larger inhibition zone than CTZ-MBG as the increased viscosity of CTZ-MBG resulted in more retardation and higher fluctuations in drug diffusion. As there were no detectable visual changes in CAM blood vessels after applying CTZ-ME or CTZ-MBG, both formulations were non-irritants. CTZ-ME and CTZ-MBG could deliver the drug through CAM, the model for buccal delivery. Additionally, they did not cause irritancy and had effective antifungal activity against C. albicans. The results indicated that CTZ-ME and CTZ-MBG were potential effective antifungal formulations to treat oral candidiasis. © 2017 Royal Pharmaceutical Society.

  8. Sub-paresthesia spinal cord stimulation reverses thermal hyperalgesia and modulates low frequency EEG in a rat model of neuropathic pain.

    Science.gov (United States)

    Koyama, Suguru; Xia, Jimmy; Leblanc, Brian W; Gu, Jianwen Wendy; Saab, Carl Y

    2018-05-08

    Paresthesia, a common feature of epidural spinal cord stimulation (SCS) for pain management, presents a challenge to the double-blind study design. Although sub-paresthesia SCS has been shown to be effective in alleviating pain, empirical criteria for sub-paresthesia SCS have not been established and its basic mechanisms of action at supraspinal levels are unknown. We tested our hypothesis that sub-paresthesia SCS attenuates behavioral signs of neuropathic pain in a rat model, and modulates pain-related theta (4-8 Hz) power of the electroencephalogram (EEG), a previously validated correlate of spontaneous pain in rodent models. Results show that sub-paresthesia SCS attenuates thermal hyperalgesia and power amplitude in the 3-4 Hz range, consistent with clinical data showing significant yet modest analgesic effects of sub-paresthesia SCS in humans. Therefore, we present evidence for anti-nociceptive effects of sub-paresthesia SCS in a rat model of neuropathic pain and further validate EEG theta power as a reliable 'biosignature' of spontaneous pain.

  9. Novel microemulsion in situ electrolyte-triggered gelling system for ophthalmic delivery of lipophilic cyclosporine A: in vitro and in vivo results.

    Science.gov (United States)

    Gan, Li; Gan, Yong; Zhu, Chunliu; Zhang, Xinxin; Zhu, Jiabi

    2009-01-05

    The objective of the present study was to design a novel microemulsion in situ electrolyte-triggered gelling system for ophthalmic delivery of a lipophilic drug, cyclosporine A (CsA). A CsA-loaded microemulsion was prepared using castor oil, Solutol HS 15 (surfactant), glycerol and water. This microemulsion was then dispersed in a Kelcogel solution to form the final microemulsion in situ electrolyte-triggered gelling system. In vitro, the viscosity of the CsA microemulsion Kelcogel system increased dramatically on dilution with artificial tear fluid and exhibited pseudo-plastic rheology. In vivo results revealed that the AUC(0-->32 h) of corneal CsA for the microemulsion Kelcogel system was approximately three-fold greater than for a CsA emulsion. Moreover, at 32 h after administration, CsA concentrations delivered by the microemulsion Kelcogel system remained at therapeutic levels in the cornea. This CsA microemulsion in situ electrolyte-triggered gelling system might provide an alternative approach to deliver prolonged precorneal residence time of CsA for preventing cornea allograft rejection.

  10. Development and in vitro-in vivo evaluation of a water-in-oil microemulsion formulation for the oral delivery of troxerutin.

    Science.gov (United States)

    Xu, Man; Yu, Qing; Zhao, Qianru; Chen, Wei; Lin, Yuanjie; Jin, Yong

    2016-01-01

    The main objective of this study was to develop and evaluate a W/O microemulsion formulation of troxerutin to improve its oral bioavailability. The W/O microemulsion was optimized using a pseudo-ternary phase diagram and evaluated for physical properties. In vitro MDCK cell permeability studies were carried out to evaluate the permeability enhancement effect of microemulsion, and in vivo absorption of troxerutin microemulsion in the intestine was compared with that of solution after single-dose administration (56.7 mg/kg) in male Wistar rats. The optimal formulation consisted of lecithin, ethanol, isopropyl myristate and water (23.30/11.67/52.45/12.59 w/w) was physicochemical stable and the mean droplet size was about 50.20 nm. In vitro study, the troxerutin-loaded microemulsion showed higher intestinal membrane permeability across MDCK monolayer when compared with the control solution. The W/O microemulsion can significantly promote the intestinal absorption of troxerutin in rats in vivo, and the relative bioavailability of the microemulsion was about 205.55% compared to control solution. These results suggest that novel W/O microemulsion could be used as an effective formulation for improving the oral bioavailability of troxerutin.

  11. Phase behaviour and microstructure of the micro-emulsions composed of cholinium-based ionic liquid, Triton X-100 and water

    International Nuclear Information System (INIS)

    Pei, Yuanchao; Huang, Yanjie; Li, Lin; Wang, Jianji

    2014-01-01

    Highlights: • The microemulsions composed of cholinium-based ionic liquid, Triton X-100 and water have been prepared and characterised. • Ternary phase diagrams of the microemulsions have been established at T = 298.15 K. • The microemulsions exhibit IL-in-water, bicontinuous and water-in-IL microstructures. • Droplets with the size smaller than 20 nm are formed in these IL-based microemulsions. - Abstract: In this paper, micro-emulsions composed of cholinium-based ionic liquids (ILs), octylphenol ethoxylate (Triton X-100) and water were prepared. These ternary systems were found to be stable over 12 months at room temperature. Their phase behaviour was investigated by using cloud titrations, and their microstructures were characterised by means of cyclic voltammetry and electrical conductance measurements at T = 298.15 K. It was shown that the micro-emulsions exhibited IL-in-water, bi-continuous and water-in-IL microstructures. Dynamic light scattering data suggest that Triton X-100 forms micelles in water, which were swelled by the ILs added. Droplets with the size about 20 nm were formed in these IL-based micro-emulsions, and the droplet size increased with the increase of the IL concentrations. These IL-based micro-emulsions may have potential in drug delivery, chemical reactions and nanomaterial preparation as a new type of nanoreactors

  12. Characterization and evaluation of an oral microemulsion containing the antitumor diterpenoid compound ent-11alpha-hydroxy-15-oxo-kaur-16-en-19-oic-acid

    Directory of Open Access Journals (Sweden)

    Lu Y

    2013-05-01

    Full Text Available Yingnian Lu,1,2 Kefeng Wu,2 Li Li,2 Yuhui He,2 Liao Cui,2 Nianci Liang,2 Bozhong Mu11Department of Chemistry, East China University of Science and Technology, Shanghai, 2Guangdong Key Laboratory for Research and Development of Natural Drugs, Guangdong Medical College, Zhanjiang, People’s Republic of ChinaAbstract: The objective of this study was to develop an oral microemulsion formulation of the antitumor diterpenoid agent, ent-11a-hydroxy-15-oxo-kaur-16-en-19-oic- acid (henceforth referred to as 5F, to enhance its bioavailability and evaluate its hepatotoxicity. Pseudoternary phase diagrams showed that the optimal microemulsion formulation contained 45% water, 10% castor oil as the oil phase, 15% Cremophor EL as the surfactant, and 30% as a cosurfactant mixture of 1,2-propanediol and polyethylene glycol (PEG-400 (2:1, w/w. The microemulsion preparation was characterized and its droplet diameter was within 50 nm. Release of 5F in vitro from the microemulsion was slightly increased compared with a suspension containing the same amount of active drug. Pharmacokinetic parameters in vivo indicated that bioavailability was markedly improved, with the relative bioavailability being 616.15% higher for the microemulsion than for the suspension. Toxicity tests showed that the microemulsion had no hepatotoxicity in mice. These results suggest the potential for 5F microemulsion to be administered by the oral route.Keywords: antitumor, diterpenoid, microemulsion, pharmacokinetics, toxicity

  13. Droplet polydispersity and shape fluctuations in AOT [bis(2-ethylhexyl)sulfosuccinate sodium salt] microemulsions studied by contrast variation small-angle neutron scattering

    DEFF Research Database (Denmark)

    Arleth, L.; Pedersen, J.S.

    2001-01-01

    Microemulsions consisting of AOT water, and decane or iso-octane are studied in the region of the phase diagram where surfactant covered water droplets are formed. The polydispersity and shape fluctuations of the microemulsion droplets are determined and compared in the two different alkane types...

  14. Study of the protective effect of hydroalcoholic extract microemulsion of Teucrium polium .L against bromobenzene -induced hepatotoxicity in mice

    Directory of Open Access Journals (Sweden)

    alihasan Rahmani

    2015-01-01

    Full Text Available Background : Liver is a major organ of the body, which can be exposed to various chemicals, drugs and many other xenobiotics such as bromobenzene. The aim of this study was to find out the protective effect of hydroalcoholic extract microemulsion of Teucrium polium against hepatotoxicity induced by bromobenzene. Materials and Methods: Animals were divided into eight groups, with ten animals in each group. Group 1-3 received respectively normal saline base of microemulsion and extract microemulsions in dose of 400 mg/kg orally for 10 days. Group 4 received bromobenzene (0.36 ml/kg, ip only on the 10th day groups 5-8 received extract microemulsions orally in doses of 50, 100, 200 and 400 mg/kg respectively, during 10 days and bromobenzene (0.36 ml/kg, ip on the 10th day 1 hour after last dose of extract. 24 hours later, the animals were bled and enzymes ALT, AST and ALP were measured. Animal liver was removed for histological studies. Results: The results showed a significant increase in liver enzyme activity by bromobenzene. The treated groups with Teucrium polium showed a significant decrease in liver enzyme activity in doses of 100, 200 and 400 mg/kg (P<0.05. Histological observations also confirmed the results. Conclusion: The results revealed that hydroalcoholic extract microemulsion of Teucrium polium has protective effect on liver toxicity induced by bromobenzene

  15. Environmentally friendly ionic liquid-in-water microemulsions for extraction of hydrophilic and lipophilic components from Flos Chrysanthemi.

    Science.gov (United States)

    Chen, Jue; Cao, Jun; Gao, Wen; Qi, Lian-Wen; Li, Ping

    2013-10-21

    Ionic liquids (ILs) have numerous chemical applications as environmentally green solvents that are extending into microemulsion applications. In this work, a novel benign IL-in-water microemulsion system modified by an IL surfactant has been proposed for simultaneous extraction of hydrophilic and lipophilic constituents from Flos Chrysanthemi (Chrysanthemum morifolium). Constituents were analyzed by rapid-resolution liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. A mixture-design approach was used to optimize the IL surfactant and the IL oil phase in the microemulsion system. Microemulsions consisting of 6.0% 1-dodecyl-3-methylimidazolium hydrogen sulfate, 0.1% 1-vinyl-3-methylimidazolium hexafluorophosphate and 93.9% water offered the acceptable extract efficiency that are comparable to or even better than conventional volatile organic solvents. This assay was fully validated with respect to the linearity of response (r(2) > 0.999 over two orders of magnitude), precision (intra-RSD < 0.49 and inter-day RSD < 2.21), and accuracy (recoveries ranging from 93.73% to 101.84%). The proposed IL-in-water microemulsion method provided an environmentally friendly alternative for efficient extraction of compounds from Flos Chrysanthemi and could be extended to complex environmental and pharmaceutical samples.

  16. [Optimizing synthesis of conjugates of superoxide dismutase and catalase with aldehyde dextrans in surfactant microemulsions in heptane].

    Science.gov (United States)

    Eremin, A N; Metelitsa, D I

    1997-01-01

    Stable microemulsions in heptane retaining considerable amounts of the polar phase were obtained by using Aerosol OT (AOT), Triton X-45, and catalase. Conjugates of superoxide dismutase (SOD) and catalase with aldehyde dextrans (AD) were synthesized in surfactant microemulsions in heptane. Effects of the reaction duration, the microemulsion polar phase volume, and concentrations of enzymes and modifiers on the properties of these conjugates were studied. The catalytic properties of conjugates depended on the nature of the surfactants used to stabilize the microemulsions, the initial concentration of protein in the reaction mixture, and the enzyme: modifier ratio. The degree of modification of the enzymes and the stabilities of their conjugates during isolation from microemulsions by a water-acetone solution depended on the concentration of the AD used. The catalytic properties of the conjugates synthesized were compared, and their stabilities in the presence of H2O2 were described. We suggested a simple method of transformation of whole kinetic curves of H2O2 conversion in coordinates 1/ln([H2O2]0/[H2O2]t - 1/t for simultaneous measurement of the constant of the catalase inactivation rate by H2O2 (Cin, S-1) and the rate constant of the catalase complex 1 interaction with the second H2O2 molecule (C2, M-1 S-1). This method was tested experimentally. Values C2 and Cin for catalase and its conjugates with ADs were compared, and these results were discussed.

  17. Reversible Statistics

    DEFF Research Database (Denmark)

    Tryggestad, Kjell

    2004-01-01

    The study aims is to describe how the inclusion and exclusion of materials and calculative devices construct the boundaries and distinctions between statistical facts and artifacts in economics. My methodological approach is inspired by John Graunt's (1667) Political arithmetic and more recent work...... within constructivism and the field of Science and Technology Studies (STS). The result of this approach is here termed reversible statistics, reconstructing the findings of a statistical study within economics in three different ways. It is argued that all three accounts are quite normal, albeit...... in different ways. The presence and absence of diverse materials, both natural and political, is what distinguishes them from each other. Arguments are presented for a more symmetric relation between the scientific statistical text and the reader. I will argue that a more symmetric relation can be achieved...

  18. Reversible manipulation of the adhesive forces of TiO{sub 2}/polybenzoxazine nanoassembled coatings through UV irradiation and thermal treatment

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Sheng-Feng; Kao, Tzu-Hao [Department of Materials Science and Engineering, National Taiwan University of Science and Technology, 43, Section 4, Keelung Road, Taipei 106, Taiwan, ROC (China); Cheng, Chih-Chia [Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei 10607, Taiwan, ROC (China); Chang, Chi-Jung [Department of Chemical Engineering, Feng Chia University, 100, Wenhwa Road, Seatwen, Taichung 40724, Taiwan, ROC (China); Chen, Jem-Kun, E-mail: jkchen@mail.ntust.edu.tw [Department of Materials Science and Engineering, National Taiwan University of Science and Technology, 43, Section 4, Keelung Road, Taipei 106, Taiwan, ROC (China)

    2015-12-01

    Graphical abstract: We developed a simple approach, mixing TiO{sub 2} nanoparticles and 3-phenyl-3,4-dihydro-2H-1,3-benzoxazine (BA), to obtain a UV-responsive surfaces after thermal treatment. Because the wettability between TiO{sub 2} nanoparticles and BA, a nanoassembled structure was generated on the surface during the coating process. Results indicate that the mixing 30 wt% TiO{sub 2} nanoparticles into PBA matrix generated the superhydrophobic surface (static water contact angle > 150°) with ca. 1° of sliding angle. The superhydrophobic TiO{sub 2}/PBA nanoassembled surface can be converted by photocatalytic oxidation into a highly hydrophilic one (static water contact angle ∼ 0°) within five minimums. Interestingly, the hydrophilic surface can be converted back into a superhydrophobic surface by heat treatment. A water droplet can be transported among the surfaces that UV-irradiated for various times. Velocity of the droplet on the 15°-titled surface could be also manipulated with UV irradiation for various times. The correlations between PBA and TiO{sub 2} nanoparticles would provide insight into the designing and developing of light-responsive surfaces. - Highlights: • Nanoassembly of PBA and TiO{sub 2} NPs are generated with superhydrophobicity. • The superhydrophobicity can be converted to hydrophilic surface within 5 min. • The hydrophilic surface can be converted back into a superhydrophobic surface. • Adhesive force of the nanoassemblies can be manipulated by UV illumination time. - Abstract: In this study we mixed TiO{sub 2} nanoparticles (NPs) with 3-phenyl-3,4-dihydro-2H-1,3-benzoxazine (BA), as a precursor to a polybenzoxazine (PBA), to generate nanocomposite surfaces possessing low surface free energies. Because of extreme phase separation between the TiO{sub 2} NPs and BA, their mixtures featured nanoassembled structures on their surfaces. After thermal curing, we obtained PBA/TiO{sub 2} nanoassembled (PTN) surfaces possessing

  19. Enhancing mechanism of intestinal absorption of highly lipophilic compounds using microemulsion – Quantitative analysis of the partitioning to the mesenteric lymph in intestinal cells

    Directory of Open Access Journals (Sweden)

    Kazunori Iwanaga

    2015-06-01

    Full Text Available The purpose of this study was to quantify the effect of the fatty acid alkyl-chain length of a polyethylene glycol (PEG glyceryl ester, which was used as a microemulsion oil component, on the partitioning of highly lipophilic compounds to the mesenteric lymph after oral administration. Oil blue N, a highly lipophilic anthraquinone derivative, was orally administered to lymph duct-cannulated and untreated rats in two kinds of different microemulsions. Gelucire® 50/13 and Gelucire® 44/14 were used as the oil component with long chain and medium chain fatty acid portions, respectively, of PEG glyceryl esters in microemulsions. The cumulative amount of oil blue N in lymph fluid was almost the same between the two microemulsions, although the transferred amount of oil component (triglyceride in the lymph after administration of the Gelucire® 50/13 microemulsion was significantly higher than that of the Gelucire® 44/14 microemulsion. On the other hand, the solubility of oil blue N in Gelucire® 44/14 was much higher than that in Gelucire® 50/13. No significant differences were observed between microemulsions in the bioavailability of oil blue N. From these data, the partitioning of oil blue N to the lymph was calculated using a mathematical model, showing that the partitioning ratios of oil blue N to the lymph fluid were almost the same for both microemulsions. The solubility of oil blue N to the oil component of the microemulsions and the transfer of triglycerides to the lymph after administration of the microemulsions counteract each other, leading to similar partitioning ratios of oil blue N to the lymph.

  20. Improvement of effect of water-in-oil microemulsion as an oral delivery system for fexofenadine: in vitro and in vivo studies

    Science.gov (United States)

    Gundogdu, E; Alvarez, I Gonzalez; Karasulu, E

    2011-01-01

    Fexofenadine (FEX) has high solubility and low permeability (BCS, Class III). In this work, novel FEX loaded water in oil microemulsion (w/o) was designed to improve bioavailability and compared with Fexofen® syrup in in vitro and in vivo studies. In addition, pharmacokinetic parameters in permeability studies were estimated by using WinNonLin software program. w/o microemulsion system was optimized using a pseudoternary phase diagram, composed of span 80/lutrol F 68 (9.5:0.5 w/w), oleic acide, isopropyl alcohol and water as surfactant mixture; oil and cosurfactant was developed for oral drug delivery. w/o microemulsion systems were characterized by phase behavior, particle size, viscosity and solubilization capacity. In vitro studies were studied using Caco-2 cell monolayer. Pharmacokinetic parameters of w/o microemulsion were investigated in rabbits and compared to Fexofen® syrup. Fexofen® syrup and microemulsion were administered by oral gavage at 6 mg/kg of the same concentration. The experimental results indicated that microemulsion (HLB = 5.53) formed nanometer sized droplets (33.29 ± 1.76) and had good physical stability. This microemulsion increased the oral bioavailability of FEX which was highly water-soluble but fairly impermeable. The relative bioavailability of FEX microemulsion was about 376.76% compared with commercial syrup in rabbits. In vitro experiments were further employed for the enhanced effect of the microemulsion for FEX. These results suggest that novel w/o microemulsion plays an important role in enhancing oral bioavailability of low permeability drugs. PMID:21904453

  1. Mechanisms of microemulsion enhancing the oral bioavailability of puerarin: comparison between oil-in-water and water-in-oil microemulsions using the single-pass intestinal perfusion method and a chylomicron flow blocking approach

    Directory of Open Access Journals (Sweden)

    Tang TT

    2013-11-01

    Full Text Available Tian-Tian Tang,1,2,3 Xiong-Bin Hu,1,2,3 De-Hua Liao,1,2,3 Xin-Yi Liu,1,2,3 Da-Xiong Xiang1,2,31Department of Pharmacy, The Second Xiangya Hospital, Central South University, Changsha, People's Republic of China; 2Institute of Clinical Pharmacy, The Second Xiangya Hospital, Central South University, Changsha, People's Republic of China; 3Key Laboratory for New Technology of Chinese Medicine Preparations of Hunan Province, Changsha, People's Republic of ChinaAbstract: The purpose of the present work was to determine the mechanisms by which microemulsions (MEs enhance the oral bioavailability of puerarin. The in situ perfusion method was used in rats to study the absorption mechanisms of an oil-in-water (O/W microemulsion (O/W-ME and a water-in-oil (W/O microemulsion (W/O-ME. The possibility of lymphatic transport of the MEs was investigated using a chylomicron flow blocking approach. The results for the absorption mechanisms in the stomach and intestines indicated that the absorption characteristics of the O/W-ME and W/O-ME depend on the segment. The W/O-ME had higher internal membrane permeability than the O/W-ME. The results of the lymphatic transport analyses showed that both the O/W-ME and W/O-ME underwent lymphatic transport and that this pathway was a major contributor to the oral bioavailability of MEs. Furthermore, the type of ME can significantly affect the absorption of puerarin through the lymphatic system due to the oil content and the form of the microemulsion after oral administration. In conclusion, these data indicate that microemulsions are an effective and promising delivery system to enhance the oral bioavailability of poorly water-soluble drugs.Keywords: microemulsion, lymphatic transport, oral bioavailability, chylomicron

  2. Preparation and Characterization of Polystyrene-Silver NanocompositeUsing MicroemulsionMethod and its Antibacterial Activity

    Directory of Open Access Journals (Sweden)

    A. Salabat

    2014-07-01

    Full Text Available Polymer nanocomposites containing metals have been used in a wide range of applications due to their versatility, and tunable characteristics including physical, chemical, biological and mechanical properties. In this research work polystyrene-silver nanocomposite has been produced using polymerization of a w/o microemulsion system. Styrene monomer was used as the oil or continues phase of the microemulsion system and polymerized following formation of Ag nanoparticles in the fluid medium. The UV-vis absorption and dynamic light scattering methods have been used to trace the growth process and size distribution of the Ag nanoparticles in the microemulsion system. Scanning electron microscopy (SEM was used to determine the morphology and particle size of the Ag particles in the synthesized nanocomposites.

  3. Preparation of starch nanoparticles in a water-in-ionic liquid microemulsion system and their drug loading and releasing properties.

    Science.gov (United States)

    Zhou, Gang; Luo, Zhigang; Fu, Xiong

    2014-08-13

    An ionic liquid microemulsion consisting of 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim]PF₆), surfactant TX-100, 1-butanol, and water was prepared. The water-in-[Bmim]PF₆ (W/IL), bicontinuous, and [Bmim]PF₆-in-water (IL/W) microregions of the microemulsion were identified by conductivity measurements. Starch nanoparticles with a mean diameter of 91.4 nm were synthesized with epichlorohydrin as cross-linker through W/IL microemulsion cross-linking reaction at 50 °C for 4 h. Fourier transform infrared spectroscopy (FTIR) data demonstrated the formation of cross-linking bonds in starch molecules. Scanning electron microscopy (SEM) revealed that starch nanoparticles were spherical and that some particles showed aggregation formation. Furthermore, drug loading and releasing properties of starch nanoparticles were investigated with mitoxantrone hydrochloride as a drug model. This work provides an efficient and environmentally friendly approach for the preparation of starch nanoparticles, which is beneficial to their further application.

  4. Fabrication of a novel scaffold of clotrimazole-microemulsion-containing nanofibers using an electrospinning process for oral candidiasis applications.

    Science.gov (United States)

    Tonglairoum, Prasopchai; Ngawhirunpat, Tanasait; Rojanarata, Theerasak; Kaomongkolgit, Ruchadaporn; Opanasopit, Praneet

    2015-02-01

    Clotrimazole (CZ)-loaded microemulsion-containing nanofiber mats were developed as an alternative for oral candidiasis applications. The microemulsion was composed of oleic acid (O), Tween 80 (T80), and a co-surfactant such as benzyl alcohol (BzOH), ethyl alcohol (EtOH) or isopropyl alcohol (IPA). The nanofiber mats were obtained by electrospinning a blended solution of a CZ-loaded microemulsion and a mixed polymer solution of 2% (w/v) chitosan (CS) and 10% (w/v) polyvinyl alcohol (PVA) at a weight ratio of 30:70. The nanofiber mats were characterized using various analytical techniques. The entrapment efficiency, drug release, antifungal activity and cytotoxicity were investigated. The average diameter of the nanofiber mats was in the range of 105.91-125.56 nm. The differential scanning calorimetry (DSC) and powder X-ray diffractometry (PXRD) results revealed the amorphous state of the CZ-loaded microemulsions incorporated into the nanofiber mats. The entrapment efficiency of CZ in the mats was approximately 72.58-98.10%, depended on the microemulsion formulation. The release experiment demonstrated different CZ release characteristics from nanofiber mats prepared using different CZ-loaded microemulsions. The extent of drug release from the fiber mats at 4h was approximately 64.81-74.15%. The release kinetics appeared to follow Higuchi's model. In comparison with CZ lozenges (10mg), the nanofiber mats exhibited more rapid killing activity. Moreover, the nanofiber mats demonstrated desirable mucoadhesive properties and were safe for 2h. Therefore, the nanofiber mats have the potential to be promising candidates for oral candidiasis applications. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Kinetics of low temperature polyester dyeing with high molecular weight disperse dyes by solvent microemulsion and agrosourced auxiliaries

    OpenAIRE

    Radei, Shahram; Carrión-Fité, Francisco Javier; Ardanuy Raso, Mònica; Canal Arias, José Ma

    2018-01-01

    This work focused on the evaluation of the kinetics of dyeing polyester fabrics with high molecular weight disperse dyes, at low temperature by solvent microemulsion. This study also compared the effect of two non-toxic agro-sourced auxiliaries (o-vanillin and coumarin) using a non-toxic organic solvent. A dyeing bath consisting of a micro-emulsion system involving a small proportion of n-butyl acetate was used, and the kinetics of dyeing were analysed at four temperatures (83, 90, 95 and 100...

  6. Kinetics of Low Temperature Polyester Dyeing with High Molecular Weight Disperse Dyes by Solvent Microemulsion and AgroSourced Auxiliaries

    OpenAIRE

    Shahram Radei; F. Javier Carrión-Fité; Mònica Ardanuy; José María Canal

    2018-01-01

    This work focused on the evaluation of the kinetics of dyeing polyester fabrics with high molecular weight disperse dyes, at low temperature by solvent microemulsion. This study also compared the effect of two non-toxic agro-sourced auxiliaries (o-vanillin and coumarin) using a non-toxic organic solvent. A dyeing bath consisting of a micro-emulsion system involving a small proportion of n-butyl acetate was used, and the kinetics of dyeing were analysed at four temperatures (83, 90, 95 and 100...

  7. New method to access hyperbranched polymers with uniform structure via one-pot polymerization of inimer in microemulsion.

    Science.gov (United States)

    Min, Ke; Gao, Haifeng

    2012-09-26

    A facile approach is presented for successful synthesis of hyperbranched polymers with high molecular weight and uniform structure by a one-pot polymerization of an inimer in a microemulsion. The segregated space in the microemulsion confined the inimer polymerization and particularly the polymer-polymer reaction within discrete nanoparticles. At the end of polymerization, each nanoparticle contained one hyperbranched polymer that had thousands of inimer units and low polydispersity. The hyperbranched polymers were used as multifunctional macroinitiators for synthesis of "hyper-star" polymers. When a degradable inimer was applied, the hyper-stars showed fast degradation into linear polymer chains with low molecular weight.

  8. Xingnaojing mPEG2000-PLA modified microemulsion for transnasal delivery: pharmacokinetic and brain-targeting evaluation.

    Science.gov (United States)

    Wen, Ran; Zhang, Qing; Xu, Pan; Bai, Jie; Li, Pengyue; Du, Shouying; Lu, Yang

    2016-01-01

    Xingnaojing microemulsion (XNJ-M) administered intranasally is used for stroke treatment. In order to decrease the XNJ-M-induced mucosal irritation, XNJ-M modified by mPEG2000-PLA (XNJ-MM) were prepared in a previous work. The present work aimed to assess the impact of mPEG2000-PLA on pharmacokinetic features and brain-targeting ability of XNJ-M. The bioavailability and brain-target effects of borneol and geniposide in XNJ-M and XNJ-MM were compared in mice after intravenous (i.v.) and intranasal (i.n.) administrations. Gas chromatography, high-performance liquid chromatography, and ultra-performance liquid chromatography/tandem mass spectrometry methods were developed for the quantification of borneol and geniposide. Blood and brain samples were collected from mice at different time points after i.v. and i.n. treatments with borneol at 8.0 mg/kg, geniposide at 4.12 mg/kg. In addition, near-infrared fluorescence dye, 1,1'-dioctadecyl-3,3,3',3'-tetramethyl indotricarbocyanine iodide was loaded into microemulsions to evaluate the brain-targeting ability of XNJ-M and XNJ-MM by near-infrared fluorescence imaging in vivo and ex vivo. For XNJ-M and XNJ-MM, the relative brain targeted coefficients (Re) were 134.59% and 198.09% (borneol), 89.70% and 188.33% (geniposide), respectively. Besides, significant near-infrared fluorescent signal was detected in the brain after i.n. administration of microemulsions, compared with that of groups for i.v. administration. These findings indicated that mPEG2000-PLA modified microemulsion improved drug entry into blood and brain compared with normal microemulsion: the introduction of mPEG2000-PLA in microemulsion resulted in brain-targeting enhancement of both fat-soluble and water-soluble drugs. These findings provide a basis for the significance of mPEG2000-PLA addition in microemulsion, defining its effects on the drugs in microemulsion.

  9. Laundry Detergency of Solid Non-Particulate Soil Using Microemulsion-Based Formulation.

    Science.gov (United States)

    Chanwattanakit, Jarussri; Chavadej, Sumaeth

    2018-02-01

    Laundry detergency of solid non-particulate soil on polyester and cotton was investigated using a microemulsion-based formulation, consisting of an anionic extended surfactant (C 12,13 -4PO-SO 4 Na) and sodium mono-and di-methyl naphthalene sulfonate (SMDNS) as the hydrophilic linker, to provide a Winsor Type III microemulsion with an ultralow interfacial tension (IFT). In this work, methyl palmitate (palmitic acid methyl ester) having a melting point around 30°C, was used as a model solid non-particulate (waxy) soil. A total surfactant concentration of 0.35 wt% of the selected formulation (4:0.65 weight ratio of C 12,13 -4PO-SO 4 Na:SMDNS) with 5.3 wt% NaCl was able to form a middle phase microemulsion at a high temperature (40°C),which provided the highest oil removal level with the lowest oil redeposition and the lowest IFT, and was much higher than that with a commercial detergent or de-ionized water. Most of the detached oil, whether in liquid or solid state, was in an unsolubilized form. Hence, the dispersion stability of the detached oil droplets or solidified oil particles that resulted from the surfactant adsorption played an important role in the oil redeposition. For an oily detergency, the lower the system IFT, the higher the oil removal whereas for a waxy (non-particulate) soil detergency, the lower the contact angle, the higher the solidified oil removal. For a liquefied oil, the detergency mechanism was roll up and emulsification with dispersion stability, while that for the waxy soil (solid oil) was the detachment by wettability with dispersion stability.

  10. Enhanced percutaneous permeability of diclofenac using a new U-type dilutable microemulsion.

    Science.gov (United States)

    Shevachman, Marina; Garti, Nissim; Shani, Arnon; Sintov, Amnon C

    2008-04-01

    Enhanced systemic absorption in vivo and percutaneous penetration in vitro was demonstrated after transdermal administration of diclofenac sodium formulated in U-type microemulsion. Diclofenac sodium was solubilized in a typical four-component system consisting of an oil, polyoxyethylene-10EO-oleyl alcohol (Brij 96V) as the surfactant, and 1-hexanol along water dilution line W46 (40 wt % surfactant and 60 wt % oil phase before water titration). Viscosity and small angle X-ray scattering measurements have evidenced bicontinuous structures within water fractions of 0.25 and 0.5 along the dilution line. Self-diffusion NMR studies showed that drug molecules accumulated in the interfacial film and, to some extent, dissolved in the oil. Relative to a commercial macro-emulsion cream (Voltaren Emulgel), microemulsions containing paraffin oil or isopropyl myristate increased the in vivo transdermal penetration rate of diclofenac by two order of magnitude, whereas the rat plasma levels were increased by one order of magnitude. The in vitro data obtained from excised rat skin were comparable to the in vivo results, but suffered from discrepancies from the ideal in vivo-in vitro correlation, which might be explained by optimal in vitro conditions of perfusion and hydration. It has also been found that when jojoba oil is formulated as the oil phase in the microemulsion, the penetration rate of the drug decreases significantly. Based on the three-dimensional structure of jojoba oil, the wax is presumed to prevent the drug from being freely diffused into the skin while migrating from the interfacial film into the continuous oil phase.

  11. Photolysis study of octyl p-methoxycinnamate loaded microemulsion by molecular fluorescence and chemometric approach

    Science.gov (United States)

    Nascimento, Danielle Silva; Insausti, Matías; Band, Beatriz Susana Fernández; Grünhut, Marcos

    2018-02-01

    Octyl p-methoxycinnamate (OMC) is one of the most widely used sunscreen agents. However, the efficiency of OMC as UV filter over time is affected due to the formation of the cis-isomer which presents a markedly lower extinction coefficient (εcis = 12,600 L mol- 1 cm- 1 at 291 nm) than the original trans-isomer (εtrans = 24,000 L mol- 1 cm- 1 at 310 nm). In this work, a novel carrier for OMC based on an oil-in-water microemulsion is proposed in order to improve the photostability of this sunscreen. The formulation was composed of 29.2% (w/w) of a 3:1 mixture of ethanol (co-surfactant) and decaethylene glycol mono-dodecyl ether (surfactant), 1.5% (w/w) of oleic acid (oil phase) and 69.2% (w/w) of water. This microemulsion was prepared in a simple way, under moderate stirring at 25 °C and using acceptable, biocompatible and accessible materials for topical use. OMC was incorporated in the vehicle at a final concentration of 5.0% (w/w), taking into account the maximum permitted levels established by international norms. Then, a photolysis study of the loaded formulation was performed using a continuous flow system. The direct photolysis was monitored over time by molecular fluorescence. The recorded spectra data between 370 y 490 nm were analyzed by multivariate curve resolution-alternating least squares algorithm. The kinetic rate constants corresponding to the photolysis of the trans-OMC were calculated from the concentration profiles, resulting in 0.0049 s- 1 for the trans-OMC loaded microemulsion and 0.0131 s- 1 for the trans-OMC in aqueous media. These results demonstrate a higher photostability of the trans-OMC when loaded in the proposed vehicle with respect to the free trans-OMC in aqueous media.

  12. Locus-specific microemulsion catalysts for sulfur mustard (HD) chemical warfare agent decontamination.

    Science.gov (United States)

    Fallis, Ian A; Griffiths, Peter C; Cosgrove, Terence; Dreiss, Cecile A; Govan, Norman; Heenan, Richard K; Holden, Ian; Jenkins, Robert L; Mitchell, Stephen J; Notman, Stuart; Platts, Jamie A; Riches, James; Tatchell, Thomas

    2009-07-22

    The rates of catalytic oxidative decontamination of the chemical warfare agent (CWA) sulfur mustard (HD, bis(2-chlororethyl) sulfide) and a range (chloroethyl) sulfide simulants of variable lipophilicity have been examined using a hydrogen peroxide-based microemulsion system. SANS (small-angle neutron scattering), SAXS (small-angle X-ray scattering), PGSE-NMR (pulsed-gradient spin-echo NMR), fluorescence quenching, and electrospray mass spectroscopy (ESI-MS) were implemented to examine the distribution of HD, its simulants, and their oxidation/hydrolysis products in a model oil-in-water microemulsion. These measurements not only present a means of interpreting decontamination rates but also a rationale for the design of oxidation catalysts for these toxic materials. Here we show that by localizing manganese-Schiff base catalysts at the oil droplet-water interface or within the droplet core, a range of (chloroethyl) sulfides, including HD, spanning some 7 orders of octanol-water partition coefficient (K(ow)), may be oxidized with equal efficacy using dilute (5 wt. % of aqueous phase) hydrogen peroxide as a noncorrosive, environmentally benign oxidant (e.g., t(1/2) (HD) approximately 18 s, (2-chloroethyl phenyl sulfide, C(6)H(5)SCH(2)CH(2)Cl) approximately 15 s, (thiodiglycol, S(CH(2)CH(2)OH)(2)) approximately 19 s {20 degrees C}). Our observations demonstrate that by programming catalyst lipophilicity to colocalize catalyst and substrate, the inherent compartmentalization of the microemulsion can be exploited to achieve enhanced rates of reaction or to exert control over product selectivity. A combination of SANS, ESI-MS and fluorescence quenching measurements indicate that the enhanced catalytic activity is due to the locus of the catalyst and not a result of partial hydrolysis of the substrate.

  13. Influence of a multiple emulsion, liposomes and a microemulsion gel on sebum, skin hydration and TEWL.

    Science.gov (United States)

    Mahrhauser, D; Nagelreiter, C; Baierl, A; Skipiol, J; Valenta, C

    2015-04-01

    In this study, the influence of three cosmetically relevant, priorly characterized vehicles on skin hydration, sebum content and transepidermal water loss was investigated. The chosen vehicles included a liposomal pre-formulation, a multiple W/O/W emulsion and a microemulsion gel. The in vivo effects of these vehicles were demonstrated and compared among them. The stability of the prepared vehicles was determined visually, microscopically, rheologically by pH measurements and particle size. Interactions with skin were assessed by non-invasive biophysical techniques using the Corneometer(®), Aqua Flux(®) and Sebumeter, measuring skin hydration, TEWL and skin sebum content, respectively. All vehicles remained stable over an observation period of 6 weeks. The multiple emulsion increased sebum content and skin hydration. In case of the liposomes, each monitored parameter remained almost constant. In contrast, the microemulsion gel lowered skin hydration and increased TEWL values, but even 1 week after termination of the treatment TEWL decreased almost close to control levels. All produced vehicles were proven to remain physically stable over the duration of this study. The used multiple emulsion showed very skin-friendly properties by increasing sebum and skin hydration. Likewise, the liposomal pre-formulation exhibited no negative effects. On the contrary, the investigated microemulsion gel seemed to have skin dehydrating and TEWL increasing features. However, the multiple emulsion as well as liposomes was identified to be well-tolerated vehicles for skin which might qualify them for the use in cosmetic formulations. © 2014 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

  14. Microemulsion-based synergistic dual-drug codelivery system for enhanced apoptosis of tumor cells.

    Science.gov (United States)

    Qu, Ding; Ma, Yihua; Sun, Wenjie; Chen, Yan; Zhou, Jing; Liu, Congyan; Huang, Mengmeng

    2015-01-01

    A microemulsion-based synergistic dual-drug codelivery system was developed for enhanced cell apoptosis by transporting coix seed oil and etoposide into A549 (human lung carcinoma) cells simultaneously. Results obtained by dynamic light scattering showed that an etoposide (VP16)-loaded coix seed oil microemulsion (EC-ME) delivery system had a small size around 35 nm, a narrow polydispersity index, and a slightly negative surface charge. The encapsulating efficiency and total drug loading rate were 97.01% and 45.48%, respectively, by high-performance liquid chromatography. The release profiles at various pH values showed an obvious pH-responsive difference, with the accumulated amount of VP16 released at pH 4.5 (and pH 5.5) being 2.7-fold higher relative to that at pH 7.4. Morphologic alteration (particle swelling) associated with a mildly acidic pH environment was found on transmission electron microscopy. In the cell study, the EC-ME system showed a significantly greater antiproliferative effect toward A549 cells in comparison with free VP16 and the mixture of VP16 and coix seed oil. The half-maximal inhibitory concentration of the EC-ME system was 3.9-fold and 10.4-fold lower relative to that of free VP16 and a mixture of VP16 and coix seed oil, respectively. Moreover, fluorescein isothiocyanate and VP16 (the green fluorescent probe and entrapped drug, respectively) were efficiently internalized into the cells by means of coix seed oil microemulsion through intuitive observation and quantitative measurement. Importantly, an EC-ME system containing 20 μg/mL of VP16 showed a 3.3-fold and 3.5-fold improvement in induction of cell apoptosis compared with the VP-16-loaded microemulsion and free VP16, respectively. The EC-ME combination strategy holds promise as an efficient drug delivery system for induction of apoptosis and treatment of lung cancer.

  15. Small angle neutron scattering study on a phase separation in a 3-component microemulsion system

    International Nuclear Information System (INIS)

    Seto, Hideki; Yokoi, Eiji; Komura, Shigehiro; Schwahn, Dietmar; Mortensen, Kell; Suzuki, Junichi; Funahashi, Satoru; Ito, Yuji.

    1993-01-01

    The mixture of three components, water, n-decane and 2-ethylhexylsulfosuccinate (AOT), is a well-known system that forms a 'water-in-oil' microemulsion at room temperature and decomposes with increasing temperature, thereby being associated with a critical phenomenon. Experimental results in previous literature, indicate that the phenomenon is interpreted to be that of the 3D-Ising, but we obtained the meanfield behavior of the susceptibility at 'near-critical region' by a small angle neutron scattering. The observed spinodal and binodal points were well explained assuming the van der Waals free energy expression. (author)

  16. A microemulsion preparation of nanoparticles of europium in silica with luminescence enhancement using silver

    International Nuclear Information System (INIS)

    Ma Zhiya; Dosev, Dosi; Kennedy, Ian M

    2009-01-01

    A facile one-pot microemulsion method has been developed for the synthesis of spherical silver core-silica shell (Ag-SiO 2 ) nanoparticles with europium chelates doped in the shell through a silane agent. The method is significantly more straightforward than other extant methods. Measurements of the luminescent emissions from the Ag-SiO 2 nanoparticles, in comparison with control silica nanoparticles without silver cores, showed that the presence of the silver cores can increase the fluorescence intensity approximately 24-fold and decrease the luminescence lifetime. This enhancement offers a potential increase in overall particle detectability with increased fluorophore photostability.

  17. Neutron spin echo studies of the effects of temperature and pressure in a ternary microemulsion

    CERN Document Server

    Kawabata, Y; Seto, H; Takeda, T; Komura, S; Schwahn, D

    2002-01-01

    In order to clarify the self-assembling mechanisms in complex fluids involving amphiphiles, we have investigated dynamic features of amphiphilic membranes and droplets at high temperature and at high pressure in a ternary microemulsion, consisting of AOT, water, and n-decane. A high-pressure cell for neutron spin echo (NSE) experiments has been improved, and the static and dynamic features of droplets are observed in detail by means of small angle neutron scattering and NSE. It is found that the size fluctuation and the diffusion of droplets are enhanced by increasing temperature, while they are suppressed by increasing pressure. (orig.)

  18. Study of ignition characteristics of microemulsion of coconut oil under off diesel engine conditions

    Directory of Open Access Journals (Sweden)

    Mahir H. Salmani

    2015-09-01

    Full Text Available The increasing awareness of the depletion of fossil fuel resources and the environmental benefits motivates the use of vegetable oils, however there is little known information about ignition and combustion characteristics of vegetable oil based fuels under off diesel engine conditions. These conditions are normally reached either during starting or when the engine is sufficiently worn out. A fuel was prepared by co-solvent blending of coconut oil with 20% butyl alcohol and was analysed. An experimental study of the measurement of ignition delay (ID characteristics of conical fuel sprays impinging on hot surface in cylindrical combustion chamber was carried out. The objective of the study was to investigate the effect of hot surface temperatures on ignition delays of microemulsion of coconut oil at various ambient air pressures and temperatures which would have reached under off diesel engine conditions. An experimental set-up was designed and developed for a maximum air pressure of 200 bar and a maximum temperature of 800 °C with the emphasis on optical method for the measurement of ignition delay. Hot surface temperature range chosen was 300–450 °C and ambient air pressure (inside the combustion chamber range chosen was 10–25 bar. Present study shows that at fixed injection pressure and fixed ambient (hot surface temperature, at higher ambient air pressure (25 bar inside the combustion chamber, ignition delay of diesel and microemulsion of coconut oil are comparable and therefore are having matching combustion characteristics. Although a pressure of 25 bar is much less than the precombustion pressure of most diesel engines but again conclusively establish that combustion characteristics are same despite lower air pressure, temperature and lower injection pressure. At higher injection pressure ignition delay of microemulsion of coconut oil and pure diesel attains the lower value at the same ambient air pressure inside the

  19. High-Yield Synthesis of Zinc Oxide Nanoparticles from Bicontinuous Microemulsions

    Directory of Open Access Journals (Sweden)

    S. López-Cuenca

    2011-01-01

    Full Text Available The high-yield synthesis of zinc oxide (ZnO primary nanoparticles with high purity and with diameters between 6 and 22 nm using bicontinuous microemulsions is reported in this work. The ZnO nanoparticles were made by hydrolysis of Zn(NO32 with NaOH aqueous solution and precipitation, followed by calcination of the precipitate. Higher yields and productivities of ZnO nanoparticles were obtained compared to values produced with w/o micremulsions reported in the literature. Particles were characterized by transmission electronic microscopy (TEM, X-ray diffraction, and atomic absorption spectroscopy.

  20. An environment-friendly microemulsion approach to α-FeOOH nanorods at room temperature

    International Nuclear Information System (INIS)

    Geng Fengxia; Zhao Zhigang; Cong Hongtao; Geng Jianxin; Cheng Huiming

    2006-01-01

    α-FeOOH nanorods have been prepared at room temperature by an environment-friendly microemulsion approach. X-ray diffraction and transmission electron microscopy revealed that the single-crystalline orthorhombic α-FeOOH nanorods are 8.2 ± 1.5 nm in diameter and 106 ± 16 nm in length. Furthermore, the mechanism for the formation of α-FeOOH nanorods is preliminarily presented. This method may be widely used for reference to fabricate other inorganic one-dimensional nanostructured materials and easily realized in industrial-scale synthesis

  1. Determination of in vivo behavior of mitomycin C-loaded o/w soybean oil microemulsion and mitomycin C solution via gamma camera imaging.

    Science.gov (United States)

    Kotmakçı, Mustafa; Kantarcı, Gülten; Aşıkoğlu, Makbule; Ozkılıç, Hayal; Ertan, Gökhan

    2013-09-01

    In this study, a microemulsion system was evaluated for delivery of mitomycin C (MMC). To track the distribution of the formulated drug after intravenous administration, radiochemical labeling and gamma scintigraphy imaging were used. The aim was to evaluate a microemulsion system for intravenous delivery of MMC and to compare its in vivo behavior with that of the MMC solution. For microemulsion formulation, soybean oil was used as the oil phase. Lecithin and Tween 80 were surfactants and ethanol was the cosurfactant. To understand the whole body localization of MMC-loaded microemulsion, MMC was labeled with radioactive technetium and gamma scintigraphy was applied for visualization of drug distribution. Radioactivity in the bladder 30 minutes after injection of the MMC solution was observed, according to static gamma camera images. This shows that urinary excretion of the latter starts very soon. On the other hand, no radioactivity appeared in the urinary bladder during the 90 minutes following the administration of MMC-loaded microemulsion. The unabated radioactivity in the liver during the experiment shows that the localization of microemulsion formulation in the liver is stable. In the light of the foregoing, it is suggested that this microemulsion formulation may be an appropriate carrier system for anticancer agents by intravenous delivery in hepatic cancer chemotherapy.

  2. Characterization and evaluation of an oral microemulsion containing the antitumor diterpenoid compound ent-11alpha-hydroxy-15-oxo-kaur-16-en-19-oic-acid.

    Science.gov (United States)

    Lu, Yingnian; Wu, Kefeng; Li, Li; He, Yuhui; Cui, Liao; Liang, Nianci; Mu, Bozhong

    2013-01-01

    The objective of this study was to develop an oral microemulsion formulation of the antitumor diterpenoid agent, ent-11α-hydroxy-15-oxo-kaur-16-en-19-oic-acid (henceforth referred to as 5F), to enhance its bioavailability and evaluate its hepatotoxicity. Pseudoternary phase diagrams showed that the optimal microemulsion formulation contained 45% water, 10% castor oil as the oil phase, 15% Cremophor EL as the surfactant, and 30% as a cosurfactant mixture of 1,2-propanediol and polyethylene glycol (PEG)-400 (2:1, w/w). The microemulsion preparation was characterized and its droplet diameter was within 50 nm. Release of 5F in vitro from the microemulsion was slightly increased compared with a suspension containing the same amount of active drug. Pharmacokinetic parameters in vivo indicated that bioavailability was markedly improved, with the relative bioavailability being 616.15% higher for the microemulsion than for the suspension. Toxicity tests showed that the microemulsion had no hepatotoxicity in mice. These results suggest the potential for 5F microemulsion to be administered by the oral route.

  3. Design of Embedded Metal Catalysts via Reverser Micro-Emulsion System: a Way to Suppress Catalyst Deactivation by Metal Sintering

    KAUST Repository

    Al Mana, Noor

    2016-01-01

    are embedded inside the protecting shell have attracted a lot of researchers working in the field of catalysis owing to their enhanced physical and chemical properties suppress catalyst deactivation. Also, a new active site generated at the interface between

  4. Reverse osmosis application studies

    International Nuclear Information System (INIS)

    Golomb, A.

    1982-02-01

    To assess the feasibility of applying reverse osmosis (RO) and ultrafiltration (UF) for effective treatment of process and waste streams from operations at Ontario Hydro's thermal and nuclear stations, an extensive literature survey has been carried out. It is concluded that RO is not at present economic for pretreatment of Great Lakes water prior to ion exchange demineralization for boiler makeup. Using both conventional and novel commercial membrane modules, RO pilot studies are recommended for treatment of boiler cleaning wastes, fly ash leachates, and flue gas desulphurization scrubber discharges for removal of heavy metals. Volume reduction and decontamination of nuclear station low-level active liquid waste streams by RO/UF also appear promising. Research programmes are proposed

  5. Microemulsions based on a sunflower lecithin-Tween 20 blend have high capacity for dissolving peppermint oil and stabilizing coenzyme Q10.

    Science.gov (United States)

    Chen, Huaiqiong; Guan, Yongguang; Zhong, Qixin

    2015-01-28

    The objectives of the present study were to improve the capability of microemulsions to dissolve peppermint oil by blending sunflower lecithin with Tween 20 and to study the possibility of codelivering lipophilic bioactive compounds. The oil loading in microemulsions with 20% (w/w) Tween 20 increased from 3% (w/w) to 20% (w/w) upon gradual supplementation of 6% (w/w) lecithin. All microemulsions had particles of lecithin. Therefore, natural surfactant lecithin can reduce the use of synthetic Tween 20 to dissolve peppermint oil and protect the degradation of dissolved lipophilic bioactive components in transparent products.

  6. Ageing, fragility and the reversibility window in bulk alloy glasses

    International Nuclear Information System (INIS)

    Chakravarty, S; Georgiev, D G; Boolchand, P; Micoulaut, M

    2005-01-01

    Non-reversing relaxation enthalpies (ΔH nr ) at glass transitions T g (x) in the P x Ge x Se 1-2x ternary display wide, sharp and deep global minima (∼0) in the 0.09 g s become thermally reversing. In this reversibility window, glasses are found not to age, in contrast to ageing observed for fragile glass compositions outside the window. Thermal reversibility and lack of ageing seem to be paradigms of self-organization which molecular glasses share with protein structures which repetitively and reversibly change conformation near T g and the folding temperature respectively. (letter to the editor)

  7. Assessment of improved buccal permeation and bioavailability of felodipine microemulsion-based cross-linked polycarbophil gel.

    Science.gov (United States)

    Singh, Mahendra; Kanoujia, Jovita; Parashar, Poonam; Arya, Malti; Tripathi, Chandra B; Sinha, V R; Saraf, Shailendra K; Saraf, Shubhini A

    2018-06-01

    The oral bioavailability of felodipine (FEL) is very low, i.e., about 15%. This could be due to low water solubility and hepatic first-pass effect. The objective of the present study was to develop FEL microemulsion-based gel, to bypass the first pass effect, for buccal delivery. The optimized FEL microemulsion (OPT-MEF) was used to prepare buccoadhesive gels, with varying concentrations of hydroxypropyl methylcellulose (HPMC) E4M and polycarbophil (PCP), and evaluated. The cross-linking of the PCP gelling agent was done by adjusting the pH with a neutralizing agent, triethanolamine (TEA). The formulations, namely drug suspension, OPT-MEF, microemulsion-based buccal gel containing 1% w/v (MEF-E4M1), 2% w/v (MEF-E4M2), and 3% w/v (MEF-E4M3) of HPMC K4M and 1% w/v (MEF-PCP1), 2% w/v (MEF-PCP2), and 3% w/v (MEF-PCP3) of PCP were prepared and optimized on the basis of ex vivo permeation study, mucoadhesion force, and viscosity. The optimized buccal gel (MEF-PCP1) showed significantly higher (p microemulsion, with improved buccal permeation and pharmacokinetic parameters was developed successfully to improve the bioavailability of FEL.

  8. The crossover from mean-field to 3D-Ising critical behaviour in a 3-component microemulsion

    DEFF Research Database (Denmark)

    Seto, H.; Schwahn, D.; Yokoi, E.

    1995-01-01

    Density fluctuations and associated critical phenomena of water droplets in a water-in-oil microemulsion system have been studied, We have recently found a mean-field behavior in the ''near-critical region'', and this evidence suggested that a crossover from mean-field to non-mean-field behavior...

  9. Structure and magnetic properties of Co and Ni nano-ferrites prepared by a two step direct microemulsions synthesis

    Czech Academy of Sciences Publication Activity Database

    Pulišová, Petra; Kováč, J.; Voigt, A.; Raschman, P.

    2013-01-01

    Roč. 341, september (2013), s. 93-99 ISSN 0304-8853 Institutional support: RVO:61388980 Keywords : Precipitation in microemulsion s * Ferrite nano-powder * Magnetic properties * ZFC * FC measurements Subject RIV: CA - Inorganic Chemistry Impact factor: 2.002, year: 2013

  10. Crossover from mean field to three-dimensional ising critical behavior in a three-component microemulsion system

    DEFF Research Database (Denmark)

    Seto, H.; Schwahn, D.; Nagao, M.

    1996-01-01

    Critical density fluctuations of water droplets in an oil-rich three-component microemulsion system have been studied by small-angle neutron scattering as a function of temperature near and far from the boundary of phase decomposition. The observed data in the one-phase region are well described...

  11. Sulfur Nanoparticles Synthesis and Characterization from H2S Gas, Using Novel Biodegradable Iron Chelates in W/O Microemulsion

    Directory of Open Access Journals (Sweden)

    Harle Arti

    2008-01-01

    Full Text Available AbstractSulfur nanoparticles were synthesized from hazardous H2S gas using novel biodegradable iron chelates in w/o microemulsion system. Fe3+–malic acid chelate (0.05 M aqueous solution was studied in w/o microemulsion containing cyclohexane, Triton X-100 andn-hexanol as oil phase, surfactant, co-surfactant, respectively, for catalytic oxidation of H2S gas at ambient conditions of temperature, pressure, and neutral pH. The structural features of sulfur nanoparticles have been characterized by X-ray diffraction (XRD, transmission electron microscope (TEM, energy dispersive spectroscopy (EDS, diffused reflectance infra-red Fourier transform technique, and BET surface area measurements. XRD analysis indicates the presence of α-sulfur. TEM analysis shows that the morphology of sulfur nanoparticles synthesized in w/o microemulsion system is nearly uniform in size (average particle size 10 nm and narrow particle size distribution (in range of 5–15 nm as compared to that in aqueous surfactant systems. The EDS analysis indicated high purity of sulfur (>99%. Moreover, sulfur nanoparticles synthesized in w/o microemulsion system exhibit higher antimicrobial activity (against bacteria, yeast, and fungi than that of colloidal sulfur.

  12. New insights into the microemulsion-based chromatographic NMR resolution mechanism and its application to fragrance/flavor molecules

    Science.gov (United States)

    Hoffman, Roy E.; Aserin, Abraham; Garti, Nissim

    2012-07-01

    The NMR chromatography method is applied to a class of molecules with similar physical properties. We correlate the separation ability of microemulsions to the physical properties of the analyzed molecules. Flavor and aroma compounds are very widespread. Compositional analysis is in many cases tedious. Any new method of analysis is always useful and challenging. Here we show a new application to a class of fragrance molecules, with only a moderate variation in their chemical and physical characteristics. Up to 11 selected compounds in one mixture are resolved in one spectrum by NMR chromatography, despite the similarity of the compounds. The differences between O/W and W/O microemulsions and their resolution mechanism as applied to fragrance molecules are explained in terms of hydrophilicity and lipophilicity and effective critical packing parameters of the microemulsions. The observed diffusion rates are shown to correlate with solvation parameters. These results can be used to estimate the diffusion rates of molecules to be separated, allowing selection of the microemulsion or NMR chromatography solvent appropriate for each specific application.

  13. In vivo evaluation of anticonvulsant and antioxidant effects of phenobarbital microemulsion for transdermal administration in pilocarpine seizure rat model.

    Science.gov (United States)

    Figueiredo, Kayo Alves; Medeiros, Shirlene Cesário; Neves, Jamilly Kelly Oliveira; da Silva, José Alexsandro; da Rocha Tomé, Adriana; Carvalho, André Luis Menezes; de Freitas, Rivelilson Mendes

    2015-04-01

    This study aimed to evaluate a microemulsion system (ME) containing phenobarbital in epilepsy model induced by pilocarpine in rats and to oxidative stress and histologic lesions in hippocampus. The microemulsion was applied to the shaved back of Wistar rats. The animals were divided into the following groups: control group (P400); ME50 40mg/kg, topically-t.p.; ME100, 40mg/kg, t.p.; EM50, 40mg/kg, t.p.; phenobarbital solution 40mg/kg (PS), oral. After 60min, behavioral changes were evaluated for 1h in the model of epileptical crisis induced by pilocarpine. Phenobarbital in microemulsion was able to increase the latency for status epilepticus (SE) (p<0.05), decrease the number of epileptical crisis (ME50: p<0.001; ME100: p<0.01) and decrease mortality rate by 80% compared to P400. In EM50 and PS groups, deaths were decreased by 53.3% and 100% respectively. The ME50 and ME100 groups were able to reduce oxidative stress in experimental animals when compared to the P400. The microemulsion was still capable of reducing neuronal damage in the hippocampal areas. The results of this study come in an innovative way, demonstrating the ability of transdermal ME50 and ME100 to reduce pilocarpine-induced epileptical crisis, oxidative stress, besides neuronal damages. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. Influence of a microemulsion vehicle on cutaneous bioequivalence of a lipophilic model drug assessed by microdialysis and pharmacodynamics

    DEFF Research Database (Denmark)

    Kreilgaard, Mads; Kemme, M J; Burggraaf, J

    2001-01-01

    The aim of the study was to investigate the cutaneous bioequivalence of a lipophilic model drug (lidocaine) applied in a novel topical microemulsion vehicle, compared to a conventional oil-in-water (O/W) emulsion, assessed by a pharmacokinetics microdialysis model and a pharmacodynamic method....

  15. Food grade microemulsion systems: Sunflower oil/castor oil derivative-ethanol/water. Rheological and physicochemical analysis.

    Science.gov (United States)

    Mori Cortés, Noelia; Lorenzo, Gabriel; Califano, Alicia N

    2018-05-01

    Microemulsions are thermodynamically stable systems that have attracted considerable attention in the food industry as delivery systems for many hydrophobic nutrients. These spontaneous systems are highly dependent on ingredients and composition. In this work phase diagrams were constructed using two surfactants (Kolliphor RH40 and ELP), water, sunflower oil, and ethanol as cosurfactant, evaluating their physicochemical properties. Stability of the systems was studied at 25 and 60 °C, monitoring turbidity at 550 nm for over a month to identify the microemulsion region. Conductivity was measured to classify between water-in-oil and oil-in-water microemulsions. The phase diagram constructed with Kolliphor RH40 exhibited a larger microemulsion area than that formulated with Kolliphor ELP. All formulations showed a monomodal droplet size distribution with low polydispersity index (<0.30) and a mean droplet size below 20 nm. Systems with higher water content presented a Newtonian behavior; increasing the dispersed phase content produced a weak gel-like structure with pseudoplastic behavior under flow conditions that was satisfactorily modeled to obtain structural parameters. Copyright © 2018 Elsevier Ltd. All rights reserved.

  16. Microemulsion mediated synthesis of triangular shape SnO{sub 2} nanoparticles: Luminescence application

    Energy Technology Data Exchange (ETDEWEB)

    Luwang, Meitram Niraj, E-mail: mn.luwang@ncl.res.in

    2014-01-30

    The triangular prism shapes of SnO{sub 2}·xH{sub 2}O nanoparticles are prepared using microemulsion route. The effect of variation of water pool value on the formation of SnO{sub 2} nanoparticles was studied. There is the quantum size effect in absorption study of SnO{sub 2} nanoparticles. With the increase of the water pool value, there is a decrease in the band edge absorption energy suggesting the weak quantum confinement effect (QCE) in SnO{sub 2} nanoparticles. Quenching effect increases with increase of water to surfactant ratio in luminescence. There is no significant effect in lifetime values for SnO{sub 2} nanoparticles in both microemulsion and powder form. SnO{sub 2} nanoparticles show green emission due to oxygen vacancy. SnO{sub 2} nanoparticles when doped with Eu{sup 3+} ions give the enhanced luminescence of Eu{sup 3+} due to the surface mediated energy transfer from SnO{sub 2} to Eu{sup 3+} ion.

  17. Structure, viscoelasticity, and interfacial dynamics of a model polymeric bicontinuous microemulsion

    Energy Technology Data Exchange (ETDEWEB)

    Hickey, Robert J.; Gillard, Timothy M.; Irwin, Matthew T.; Lodge, Timothy P.; Bates, Frank S. (UMM)

    2016-01-01

    We have systematically studied the equilibrium structure and dynamics of a polymeric bicontinuous microemulsion (BμE) composed of poly(cyclohexylethylene) (PCHE), poly(ethylene) (PE), and a volumetrically symmetric PCHE–PE diblock copolymer, using dynamic mechanical spectroscopy, small angle X-ray and neutron scattering, and transmission electron microscopy. The BμE was investigated over an 80 °C temperature range, revealing a structural evolution and a rheological response not previously recognized in such systems. As the temperature is reduced below the point associated with the lamellar-disorder transition at compositions adjacent to the microemulsion channel, the interfacial area per chain of the BμE approaches that of the neat (undiluted) lamellar diblock copolymer. With increasing temperature, the diblock-rich interface swells through homopolymer infiltration. Time–temperature-superposed linear dynamic data obtained as a function of frequency show that the viscoelastic response of the BμE is strikingly similar to that of the fluctuating pure diblock copolymer in the disordered state, which we associate with membrane undulations and the breaking and reforming of interfaces. This work provides new insights into the structure and dynamics that characterize thermodynamically stable BμEs in the limits of relatively weak and strong segregation.

  18. Fluorescence quenching of uric acid solubilized in bicontinuous microemulsion by nitrobenzene

    Directory of Open Access Journals (Sweden)

    Maurice O. Iwunze

    2013-02-01

    Full Text Available Abstract: Uric Acid is known to be practically insoluble in aqueous and alcoholic media. However, it exhibits a reasonable solubility in a Bicontinuous Microemulsion system – a 15-fold or more increase in solubility in this system compared to its solubility in water. The bicontinuous microemulsion is made up of three components –Dodecane-Surfactant-water. Uric acid solubilized in this system is quenched by nitrobenzene. The obtained fluorescence data do not obey the Stern-Volmer equation when plotted accordingly. Therefore, the modified Stern-Volmer equation was used to analyze the data. It was observed that only one third (1/3 of uric acid is accessible to quenching in this medium and the reaction is diffusion-limited. The Stern-Volmer quenching constant, KSV, was calculated to be 130 M-1 and the fluorescence lifetime, 0, the quantum yield,, and the bimolecular quenching rate constant, kq, were calculated as 10.6 nanoseconds, 0.06 and 1.231010 M-1s-1, respectively.

  19. Microemulsion synthesis and magnetic properties of FexNi(1-x) alloy nanoparticles

    Science.gov (United States)

    Beygi, H.; Babakhani, A.

    2017-01-01

    This paper investigates synthesis of FexNi(1-x) bimetallic nanoparticles by microemulsion method. Through studying the mechanism of nanoparticles formation, it is indicated that synthesis of nanoparticles took placed by simultaneous reduction of metal ions and so nanoparticles structure is homogeneous alloy. FexNi(1-x) nanoparticles with different sizes, morphologies and compositions were synthesized by changing the microemulsion parameters such as water/surfactant/oil ratio, presence of co-surfactant and NiCl2·6H2O to FeCl2·4H2O molar ratio. Synthesized nanoparticles were characterized by transmission electron microscopy, particle size analysis, X-ray diffraction, atomic absorption and thermogravimetric analyses. The results indicated that, presence of butanol as co-surfactant led to chain-like arrangement of nanoparticles. Also, finer nanoparticles were synthesized by decreasing the amount of oil and water and increasing the amount of CTAB. The results of vibrating sample magnetometer suggested that magnetic properties of FexNi(1-x) alloy nanoparticles were affected by composition, size and morphology of the particles. Spherical and chain-like FexNi(1-x) alloy nanoparticles were superparamagnetic and ferromagnetic, respectively. Furthermore, higher iron in the composition of nanoparticles increases the magnetic properties.

  20. Microemulsion mediated synthesis of triangular shape SnO2 nanoparticles: Luminescence application

    International Nuclear Information System (INIS)

    Luwang, Meitram Niraj

    2014-01-01

    The triangular prism shapes of SnO 2 ·xH 2 O nanoparticles are prepared using microemulsion route. The effect of variation of water pool value on the formation of SnO 2 nanoparticles was studied. There is the quantum size effect in absorption study of SnO 2 nanoparticles. With the increase of the water pool value, there is a decrease in the band edge absorption energy suggesting the weak quantum confinement effect (QCE) in SnO 2 nanoparticles. Quenching effect increases with increase of water to surfactant ratio in luminescence. There is no significant effect in lifetime values for SnO 2 nanoparticles in both microemulsion and powder form. SnO 2 nanoparticles show green emission due to oxygen vacancy. SnO 2 nanoparticles when doped with Eu 3+ ions give the enhanced luminescence of Eu 3+ due to the surface mediated energy transfer from SnO 2 to Eu 3+ ion.

  1. A new biocompatible microemulsion increases extraction yield and bioavailability of Andrographis paniculata.

    Science.gov (United States)

    Liu, Xiao-Yan; Niu, Xin; Feng, Qian-Jin; Yang, Xue-Zhi; Wang, Dan-Wei; Zhao, Tong; Li, Lei; DU, Hong

    2016-09-01

    The purpose of this study was to design and prepare a biocompatible microemulsion of Andrographis paniculata (BMAP) containing both fat-soluble and water-soluble constituents. We determined the contents of active constituents of BMAP and evaluated its bioavailability. The biocompatible microemulsion (BM), containing lecithin and bile salts, was optimized in the present study, showing a good physical stability. The mean droplet size was 19.12 nm, and the average polydispersity index (PDI) was 0.153. The contents of andrographolide and dehydroandrographolide in BMAP, as determined by high performance liquid chromatography (HPLC), were higher than that in ethanol extraction. The pharmacokinetic results of BMAP showed that the AUC0-7 and AUC0→∞ values of BMAP were 2.267 and 27.156 μg·mL(-1)·h(-1), respectively, and were about 1.41-fold and 6.30-fold greater than that of ethanol extraction, respectively. These results demonstrated that the bioavailability of and rographolide extracted by BMAP was significantly higher than that extracted by ethanol. In conclusion, the BMAP preparation displayed ann improved dose form for future clinical applications. Copyright © 2016 China Pharmaceutical University. Published by Elsevier B.V. All rights reserved.

  2. Enhancement of anti-cholinesterase activity of Zingiber cassumunar essential oil using a microemulsion technique.

    Science.gov (United States)

    Okonogi, S; Chaiyana, W

    2012-10-01

    The aim of the present study was to enhance the cholinesterase inhibitory activity of Zingiber cassumunar (ZC) oil using a microemulsion (ME) technique. Pseudoternary phase diagrams of the oil, water, and surfactant/co-surfactant mixture were constructed using a water titration method. Effects of co-surfactant, surfactant/co-surfactant ratio, ionic strength, and pH were examined by means of the microemulsion region which existed in the phase diagrams. The inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) were tested by Ellman's colorimetric assay. It was found that ZC oil possesses inhibitory activity against not only AChE but also BChE. Formulation of ZC oil as ME revealed that alkyl chain length and number of hydroxyl groups of co-surfactant exhibited a remarkable effect on the pseudoternary phase diagram. Longer alkyl chains and more hydroxyl groups gave smaller regions of MEs. Ionic strength also affected the ME region. However, the phase behavior was hardly influenced by pH. The suitable ZC oil ME was composed of Triton X-114 in combination with propylene glycol. The anti-cholinesterase activity of this ME was much higher than that of native ZC oil. It exhibited twenty times and twenty five times higher inhibitory activity against AChE and BChE, respectively. ZC oil loaded ME is an attractive formulation for further characterization and an in vivo study in an animal model with Alzheimer's disease.

  3. Separation of corticosteroids by microemulsion EKC with diethyl L-tartrate as the oil phase.

    Science.gov (United States)

    Wu, Chi-Hung; Chen, Tse-Hsien; Huang, Kuan-Pin; Wang, Guan-Ren; Liu, Chuen-Ying

    2007-10-01

    A novel microemulsion based on a mixture of diethyl L-tartrate (DET) and SDS was developed for the microemulsion EKC (MEEKC) determination of structurally related steroids. The system consisted of 0.5% w/w DET, 1.7% w/w SDS, 1.2% w/w 1-butanol, 89.6% w/w phosphate buffer (40 mM, pH 7.0), and 7% w/w ACN. With an applied voltage of +10 kV, a baseline separation of aldosterone (A), cortisone acetate (CA), dexamethasone (D), hydrocortisone (H), hydrocortisone acetate (HA), prednisolone (P), prednisolone acetate (PA), prednisone (Ps), triamcinolone (T), and triamcinolone acetonide (TA) could be achieved. Under the optimized conditions, the reproducibility of the retention time (n = 4) for most of the compounds was less than +/-0.8% with the exception of A, Ps, and T. The average number of theoretical plates was 18 800 plates/m. The results were compared with those achieved by the modified micellar EKC (MEKC). MEEKC showed obvious advantages over MEKC for the separation of highly hydrophobic substances. To further evaluate the system, we tested the MEEKC method by analyzing corticosteroids in a spiked urine sample.

  4. Crystallization from microemulsions ? a novel method for the preparation of new crystal forms of aspartame

    Science.gov (United States)

    Füredi-Milhofer, Helga; Garti, N.; Kamyshny, A.

    1999-03-01

    Solubilization and crystallization of the artificial sweetener aspartame (APM), in water/isooctane microemulsions stabilized with sodium diisooctyl sulfosuccinate (AOT) has been investigated. The amount of aspartame that could be solubilized depended primarily on the amount of surfactant and on the temperature. The maximum AOT/aspartame molar ratio at the w/o interface is shown to be 6.2 at 25°C. It was concluded that the dipeptide is located at the w/o interface interspersed between surfactant molecules and that it acts as a cosurfactant. A new crystal form, APM III, was obtained by cooling of hot w/isooctane/AOT microemulsions containing solubilized aspartame. The new crystal form exhibits a distinct X-ray diffraction powder pattern, as well as changes in the FTIR spectra, thermogravimetric and DSC patterns. H-NMR spectra of APM III dissolved in D 2O were identical to the spectrum of commercial aspartame recorded under the same conditions. The new crystal form has greatly improved dissolution kinetics.

  5. Fine tuning of size and morphology of magnetite nanoparticles synthesized by microemulsion

    Science.gov (United States)

    Singh, Pinki; Upadhyay, Chandan

    2018-05-01

    The synthesis parameters crucially affect the physical and chemical parameters of nanoparticles. Magnetite (Fe3O4) nanoparticles were synthesized using microemulsion method. This method does not require high temperature synthesis, nitrogen environment and/or pH regulation during synthesis process. We are presenting here a systematic study on role of different associated parameters of microemulsion synthesis method on the formation of Fe3O4 nanoparticles. From X-ray Diffraction and Transmission Electron Micoscopy data analysis the size of synthesized particles were observed to be <10 nm. The critical concentration of ferrous-ferric solution to obtain particles in single phase has been found to be ≤0.09 M and ≤0.184 M, respectively. The variation of molar concentration (0.01 M ≤x≤ 0.1 M) of CTAB leads to formation of Fe3O4 nano-scale particles of distinct morphologies e.g. nano-cubes, pentagons and spheres. The number of ferrous and ferric ions involved in the formation decides the size of the nanoparticles. The single crystallographic phase is obtained in reaction temperature range of 65° C

  6. Comparison and functionalization study of microemulsion-prepared magnetic iron oxide nanoparticles.

    Science.gov (United States)

    Okoli, Chuka; Sanchez-Dominguez, Margarita; Boutonnet, Magali; Järås, Sven; Civera, Concepción; Solans, Conxita; Kuttuva, Gunaratna Rajarao

    2012-06-05

    Magnetic iron oxide nanoparticles (MION) for protein binding and separation were obtained from water-in-oil (w/o) and oil-in-water (o/w) microemulsions. Characterization of the prepared nanoparticles have been performed by TEM, XRD, SQUID magnetometry, and BET. Microemulsion-prepared magnetic iron oxide nanoparticles (ME-MION) with sizes ranging from 2 to 10 nm were obtained. Study on the magnetic properties at 300 K shows a large increase of the magnetization ~35 emu/g for w/o-ME-MION with superparamagnetic behavior and nanoscale dimensions in comparison with o/w-ME-MION (10 emu/g) due to larger particle size and anisotropic property. Moringa oleifera coagulation protein (MOCP) bound w/o- and o/w-ME-MION showed an enhanced performance in terms of coagulation activity. A significant interaction between the magnetic nanoparticles and the protein can be described by changes in fluorescence emission spectra. Adsorbed protein from MOCP is still retaining its functionality even after binding to the nanoparticles, thus implying the extension of this technique for various applications.

  7. Ferroelectric self-assembled PbTiO{sub 3} perovskite nanostructures onto (100)SrTiO{sub 3} substrates from a novel microemulsion aided sol-gel preparation method

    Energy Technology Data Exchange (ETDEWEB)

    Calzada, M L [Institucion Ciencia de Materiales de Madrid (CSIC), Cantoblanco, E-28049 Madrid (Spain); Torres, M [Institucion Ciencia de Materiales de Madrid (CSIC), Cantoblanco, E-28049 Madrid (Spain); Fuentes-Cobas, L E [Centro de Investigacion en Materiales Avanzados, Chihuahua (Mexico); Mehta, A [Stanford Synchrotron Radiation Laboratory, Menlo Park, CA (United States); Ricote, J [Institucion Ciencia de Materiales de Madrid (CSIC), Cantoblanco, E-28049 Madrid (Spain); Pardo, L [Institucion Ciencia de Materiales de Madrid (CSIC), Cantoblanco, E-28049 Madrid (Spain)

    2007-09-19

    A novel preparation method, which involves the use of microemulsions, sol-gel chemistry and chemical solution deposition, has been developed in this work for the preparation of layers of PbTiO{sub 3} nanostructures supported on SrTiO{sub 3} substrates. A transparent solution was first prepared by mixing a PbTiO{sub 3} precursor sol and a microemulsion formed by water, cyclohexane and the surfactant Brij 30 (polyoxyethylene(4) lauryl ether). The solution was deposited onto the SrTiO{sub 3} substrate by spin-coating and dried under controlled conditions (temperature, time and relative humidity) to favor the rearrangement of the micelles in the deposited coat. After a rapid thermal treatment of crystallization at 650 deg. C, nanostructures with uniform sizes of {approx}40 nm diameter and showing periodicity in some zones of the substrate are obtained. The analysis of these nanostructures by grazing-incidence x-ray synchrotron radiation indicates that they have a perovskite structure with a <100> preferred orientation and that they are under strained conditions. Thermal treatments at higher temperatures produce the collapse of the ordered nanoparticles' network and the formation of larger isolated particles of PbTiO{sub 3} with a truncated-pyramid morphology. Piezoresponse force microscopy studies demonstrate that the spontaneous polarization of these PbTiO{sub 3} nanostructures can be switched and that they have piezoelectric activity. These results support the fabrication strategy here proposed as a promising approach for the preparation of nanoferroelectrics onto substrates of possible interest in future nanoelectronic devices.

  8. Curcumin Protects Skin against UVB-Induced Cytotoxicity via the Keap1-Nrf2 Pathway: The Use of a Microemulsion Delivery System

    Directory of Open Access Journals (Sweden)

    Maya Ben Yehuda Greenwald

    2017-01-01

    Full Text Available Curcumin was found to be beneficial in treating several skin pathologies and diseases, providing antioxidant protection due to its reducing properties and its electrophilic properties (the ability to activate the Nrf2 pathway and induce phase II cytoprotective enzymes. Nevertheless, clinical applications of curcumin are being hampered by its insufficient solubility, chemical instability, and poor absorption, leading to low efficacy in preventing skin pathologies. These limitations can be overcome by using a nanotechnology-based delivery system. Here, we elucidated the possibility of using curcumin encapsulated in a microemulsion preserving its unique chemical structure. We also examined whether curcumin microemulsion would reduce UVB-induced toxicity in skin. A significant curcumin concentration was found in the human skin dermis following topical application of a curcumin microemulsion. Moreover, curcumin microemulsion enhanced the reduction of UV-induced cytotoxicity in epidermal cells, paving the way for other incorporated electrophiles in encapsulated form protecting skin against stress-related diseases.

  9. Curcumin Protects Skin against UVB-Induced Cytotoxicity via the Keap1-Nrf2 Pathway: The Use of a Microemulsion Delivery System

    Science.gov (United States)

    Ben Yehuda Greenwald, Maya; Frušić-Zlotkin, Marina; Soroka, Yoram; Ben Sasson, Shmuel; Bitton, Ronit; Bianco-Peled, Havazelet

    2017-01-01

    Curcumin was found to be beneficial in treating several skin pathologies and diseases, providing antioxidant protection due to its reducing properties and its electrophilic properties (the ability to activate the Nrf2 pathway and induce phase II cytoprotective enzymes). Nevertheless, clinical applications of curcumin are being hampered by its insufficient solubility, chemical instability, and poor absorption, leading to low efficacy in preventing skin pathologies. These limitations can be overcome by using a nanotechnology-based delivery system. Here, we elucidated the possibility of using curcumin encapsulated in a microemulsion preserving its unique chemical structure. We also examined whether curcumin microemulsion would reduce UVB-induced toxicity in skin. A significant curcumin concentration was found in the human skin dermis following topical application of a curcumin microemulsion. Moreover, curcumin microemulsion enhanced the reduction of UV-induced cytotoxicity in epidermal cells, paving the way for other incorporated electrophiles in encapsulated form protecting skin against stress-related diseases. PMID:28757910

  10. Oral bioavailability enhancement of raloxifene by developing microemulsion using D-optimal mixture design: optimization and in-vivo pharmacokinetic study.

    Science.gov (United States)

    Shah, Nirmal; Seth, Avinashkumar; Balaraman, R; Sailor, Girish; Javia, Ankur; Gohil, Dipti

    2018-04-01

    The objective of this work was to utilize a potential of microemulsion for the improvement in oral bioavailability of raloxifene hydrochloride, a BCS class-II drug with 2% bioavailability. Drug-loaded microemulsion was prepared by water titration method using Capmul MCM C8, Tween 20, and Polyethylene glycol 400 as oil, surfactant, and co-surfactant respectively. The pseudo-ternary phase diagram was constructed between oil and surfactants mixture to obtain appropriate components and their concentration ranges that result in large existence area of microemulsion. D-optimal mixture design was utilized as a statistical tool for optimization of microemulsion considering oil, S mix , and water as independent variables with percentage transmittance and globule size as dependent variables. The optimized formulation showed 100 ± 0.1% transmittance and 17.85 ± 2.78 nm globule size which was identically equal with the predicted values of dependent variables given by the design expert software. The optimized microemulsion showed pronounced enhancement in release rate compared to plain drug suspension following diffusion controlled release mechanism by the Higuchi model. The formulation showed zeta potential of value -5.88 ± 1.14 mV that imparts good stability to drug loaded microemulsion dispersion. Surface morphology study with transmission electron microscope showed discrete spherical nano sized globules with smooth surface. In-vivo pharmacokinetic study of optimized microemulsion formulation in Wistar rats showed 4.29-fold enhancements in bioavailability. Stability study showed adequate results for various parameters checked up to six months. These results reveal the potential of microemulsion for significant improvement in oral bioavailability of poorly soluble raloxifene hydrochloride.

  11. Managing Reverse Logistics or Reversing Logistics Management?

    OpenAIRE

    Brito, Marisa

    2004-01-01

    textabstractIn the past, supply chains were busy fine-tuning the logistics from raw material to the end customer. Today an increasing flow of products is going back in the chain. Thus, companies have to manage reverse logistics as well.This thesis contributes to a better understanding of reverse logistics. The thesis brings insights on reverse logistics decision-making and it lays down theoretical principles for reverse logistics as a research field.In particular it puts together a framework ...

  12. Physicochemical studies of mixed surfactant microemulsions with isopropyl myristate as oil.

    Science.gov (United States)

    Bardhan, Soumik; Kundu, Kaushik; Saha, Swapan K; Paul, Bidyut K

    2013-07-15

    The present study is focused on evaluation of interfacial compositions and thermodynamic properties of w/o mixed surfactant [(sodium dodecylsulfate, SDS/polyoxyethylene (23) lauryl ether, Brij-35)/1-pentanol (Pn)/isopropyl myristate (IPM)] microemulsions under various physicochemical conditions by the dilution method. The number of moles of Pn at the interface (n(a)(i)) and bulk oil (n(a)(o)), and various thermodynamic parameters [viz. standard Gibbs free energy (ΔG(o→i)(0)), standard enthalpy (ΔH(o→i)(0)), and standard entropy (ΔS(o→i)(0)) of the transfer of Pn from bulk oil to the interface] have been found to be dependent on the molar ratio of water to surfactant (ω), concentration of Brij-35 (X(Brij-35)), and temperature. Temperature-insensitive microemulsions with zero specific heat capacity (ΔC(p)(0))(o→i) have been formed at specific compositions. The intrinsic enthalpy change of the transfer process (ΔH(0))(o→i)* has been evaluated from linear correlation between ΔH(o→i)(0) and ΔS(o→i)(0) at different experimental temperatures. The present report also aims at a precise characterization on the basis of molecular interactions between the constituents and provides insight into the nature of the oil/water interfaces of these systems by conductivity and dynamic light scattering studies as a function of ω and X(Brij-35). Conductivity studies reveal that incorporation of Brij-35 in non-percolating water/SDS/Pn/IPM systems makes them favorable for ω-induced percolation behavior up to X(Brij-35) ≤ 0.5. But further addition of Brij-35 causes a decrease in conductivity with increasing ω. Furthermore, the hydrodynamic diameters of the microemulsion droplets increase with increase in both X(Brij-35) and ω. Correlations of the results in terms of the evaluated physicochemical parameters have been attempted. Copyright © 2013 Elsevier Inc. All rights reserved.

  13. Investigation of surfactant/cosurfactant synergism impact on ibuprofen solubilization capacity and drug release characteristics of nonionic microemulsions.

    Science.gov (United States)

    Djekic, Ljiljana; Primorac, Marija; Filipic, Slavica; Agbaba, Danica

    2012-08-20

    The current study investigates the performances of the multicomponent mixtures of nonionic surfactants regarding the microemulsion stabilisation, drug solubilization and in vitro drug release kinetic. The primary surfactant was PEG-8 caprylic/capric glycerides (Labrasol). The cosurfactants were commercially available mixtures of octoxynol-12 and polysorbate 20 without or with the addition of PEG-40 hydrogenated castor oil (Solubilisant gamma 2421 and Solubilisant gamma 2429, respectively). The oil phase of microemulsions was isopropyl myristate. Phase behaviour study of the pseudo-ternary systems Labrasol/cosurfactant/oil/water at surfactant-to-cosurfactant weight ratios (K(m)) 40:60, 50:50 and 60:40, revealed a strong synergism in the investigated tensides mixtures for stabilisation of microemulsions containing up to 80% (w/w) of water phase at surfactant +cosurfactant-to-oil weight ratio (SCoS/O) 90:10. Solubilization of a model drug ibuprofen in concentration common for topical application (5%, w/w) was achieved at the water contents below 50% (w/w). Drug free and ibuprofen-loaded microemulsions M1-M6, containing 45% (w/w) of water phase, were prepared and characterized by polarized light microscopy, conductivity, pH, rheological and droplet size measurements. In vitro ibuprofen release kinetics from the microemulsions was investigated using paddle-over-enhancer cell method and compared with the commercial 5% (w/w) ibuprofen hydrogel product (Deep Relief, Mentholatum Company Ltd., USA). The investigated microemulsions were isotropic, low viscous Bingham-type liquids with the pH value (4.70-6.61) suitable for topical application. The different efficiency of the tensides mixtures for microemulsion stabilisation was observed, depending on the cosurfactant type and K(m) value. Solubilisant gamma 2429 as well as higher K(m) (i.e., lower relative content of the cosurfactant) provided higher surfactant/cosurfactant synergism. The drug molecules were predominantly

  14. Duloxetine loaded-microemulsion system to improve behavioral activities by upregulating serotonin and norepinephrine in brain for the treatment of depression.

    Science.gov (United States)

    Sindhu, Pardeep; Kumar, Shobhit; Iqbal, Babar; Ali, Javed; Baboota, Sanjula

    2018-04-01

    Duloxetine is a well-known antidepressant molecule which is used in the treatment of depression but due to poor solubility it suffers with the drawback of low oral bioavailability. The objective of present work was to formulate and characterize duloxetine loaded microemulsion to enhance the oral bioavailability. Prepared microemulsion was studied for droplet size, zeta potential, refractive index, polydispersity index (PDI), percentage transmittance, viscosity and in vitro release study. Optimized microemulsion (D1) showed spherical droplets with mean diameter of 35.40 ± 3.11 nm, PDI of 0.170 and zeta potential values of -25.8 mV. Formulation showed good transmittance (greater than 99%), viscosity (0.205 Pa s) and refractive index (1.43 ± 0.01). Increased duloxetine release was obtained with microemulsion in comparison to drug suspension. Behavioral tests like mobility test, tail suspension test and forced swimming test performed in depressed and treated rats with duloxetine microemulsion significantly improved the behavioral activities in comparison to duloxetine suspension. Pharmacokinetic studies showed that microemulsion exhibited 1.8 times increment in bioavailability in comparison to duloxetine suspension. Copyright © 2018 Elsevier Ltd. All rights reserved.

  15. Pharmacokinetics and efficiency of brain targeting of ginsenosides Rg1 and Rb1 given as Nao-Qing microemulsion.

    Science.gov (United States)

    Li, Tao; Shu, Ya-Jun; Cheng, Jia-Yin; Liang, Run-Cheng; Dian, Shao-Na; Lv, Xiao-Xun; Yang, Meng-Qi; Huang, Shu-Ling; Chen, Gang; Yang, Fan

    2015-02-01

    Nao-Qing solution has been shown to be clinically effective in the treatment of acute ischemic stroke (AIS). The purpose of this study was to improve the pharmacokinetics and brain uptake of Nao-Qing, administered as an oil-in-water microemulsion. Sprague-Dawley (SD) rats were given Nao-Qing microemulsion by intranasal or intragastric routes. Samples of blood, brain, heart, liver, lung and kidney were collected at pre-determined time intervals, and the contents of ginsenosides Rg1 and Rb1 (active ingredients of the Nao-Qing microemulsion) were analyzed by high-performance liquid chromatography (HPLC). The results showed that contents of ginsenosides Rg1 and Rb1 in Nao-Qing microemulsion was 8475.13 ± 54.61 μg/ml and 6633.42 ± 527.27 μg/ml, respectively, and that the particle size, pH and viscosity of the microemulsion were 19.9 ± 5.07 nm, 6.1 and 3.056 × 10(-3 )Pas, respectively. Absorption of ginsenoside Rg1 was higher than that of ginsenoside Rb1, which was barely detectable after intragastric administration; furthermore, the concentration of ginsenoside Rg1 in blood and other tissues at each time point was lower for intragastric than for intranasal administration. Compared with intragastric administration, intranasal administration resulted in a shorter tmax (0.08 versus 1 h), a higher Cmax (16.65 versus 11.29 μg/ml), and a higher area under the concentration-time curve (AUC) (592.91 versus 101.70 μgċh/ml) in the brain. The relative rates of uptake (Re) and the ratio of peak concentration (Ce) in the brain were 126.31% and 147.48% for ginsenoside Rg1, respectively. These data illustrate that intranasal administration can promote the absorption of drugs in Nao-Qing microemulsion and achieve fast effect.

  16. Effect of microemulsions on transdermal delivery of citalopram: optimization studies using mixture design and response surface methodology

    Directory of Open Access Journals (Sweden)

    Huang CT

    2013-06-01

    Full Text Available Chi-Te Huang,1 Ming-Jun Tsai,2,3 Yu-Hsuan Lin,1 Yaw-Sya Fu,4 Yaw-Bin Huang,5 Yi-Hung Tsai,5 Pao-Chu Wu11School of Pharmacy, Kaohsiung Medical University, Kaohsiung City, 2Department of Neurology, China Medical University Hospital, Taichung, 3School of Medicine, Medical College, China Medical University, Taichung, 4Faculty of Biomedical Science and Environmental Biology, 5Graduate Institute of Clinical Pharmacy, Kaohsiung Medical University, Kaohsiung City, Taiwan, Republic of ChinaAbstract: The aim of this study was to evaluate the potential of microemulsions as a drug vehicle for transdermal delivery of citalopram. A computerized statistical technique of response surface methodology with mixture design was used to investigate and optimize the influence of the formulation compositions including a mixture of Brij 30/Brij 35 surfactants (at a ratio of 4:1, 20%–30%, isopropyl alcohol (20%–30%, and distilled water (40%–50% on the properties of the drug-loaded microemulsions, including permeation rate (flux and lag time. When microemulsions were used as a vehicle, the drug permeation rate increased significantly and the lag time shortened significantly when compared with the aqueous control of 40% isopropyl alcohol solution containing 3% citalopram, demonstrating that microemulsions are a promising vehicle for transdermal application. With regard to the pharmacokinetic parameters of citalopram, the flux required for the transdermal delivery system was about 1280 µg per hour. The microemulsions loaded with citalopram 3% and 10% showed respective flux rates of 179.6 µg/cm2 and 513.8 µg/cm2 per hour, indicating that the study formulation could provide effective therapeutic concentrations over a practical application area. The animal study showed that the optimized formulation (F15 containing 3% citalopram with an application area of 3.46 cm2 is able to reach a minimum effective therapeutic concentration with no erythematous reaction

  17. Morphological evolution of copper nanoparticles: Microemulsion reactor system versus batch reactor system

    Science.gov (United States)

    Xia, Ming; Tang, Zengmin; Kim, Woo-Sik; Yu, Taekyung; Park, Bum Jun

    2017-07-01

    In the synthesis of nanoparticles, the reaction rate is important to determine the morphology of nanoparticles. We investigated morphology evolution of Cu nanoparticles in this two different reactors, microemulsion reactor and batch reactor. In comparison with the batch reactor system, the enhanced mass and heat transfers in the emulsion system likely led to the relatively short nucleation time and the highly homogeneous environment in the reaction mixture, resulting in suppressing one or two dimensional growth of the nanoparticles. We believe that this work can offer a good model system to quantitatively understand the crystal growth mechanism that depends strongly on the local monomer concentration, the efficiency of heat transfer, and the relative contribution of the counter ions (Br- and Cl-) as capping agents.

  18. Patterns in the bubble-free Belousov-Zhabotinsky reaction dissolved in a microemulsion

    Science.gov (United States)

    Dähmlow, P.; Almeida, J.; Müller, S. C.

    2016-12-01

    A newly created system, namely a bubble-free Belousov-Zhabotinsky reaction embedded in a microemulsion is experimentally studied, with 1,4-cyclohexanedione used as substrate. Initially, this system shows oscillations or waves. After some minutes, waves do not form a refractory state in their wake, but the system remains excited. However, within this excited regime, a new wave emerges directly behind the initial one, causing an acceleration of the latter. The excited state lasts for several minutes. Subsequently, three different types of patterns emerge, depending on the initial chemical concentrations: wave turbulence, transient lines (TL) and an intermediate state. TL are neither Turing structures nor excitation waves. The intermediate state is a mixed pattern of TL and wave turbulence.

  19. Formulation of microemulsion propolis fluoride (PF) as varnish topical agent to stop activity of teeth caries

    Science.gov (United States)

    Sahlan, Muhamad; Prakoso, Chandra Dwi; Darwita, Risqa Rina; Hermansyah, Heri

    2017-02-01

    Topical fluoride is proven to have higher efficacy in preventing dental caries with low production cost and easy to apply. The objective of this research is to formulate alternative agent topical fluoride NH4F 5% mixed with extract ethanol propolis (EEP) in the micro-emulsion system that has high stability, antimicrobial activity, and remineralization capability to arrest teeth caries activity. By using total plate count (TPC) analysis, formulation 2.7% EEP; 6,3% surfactant; and 90,9% NH4F shows good perform to inhibit cariogenic bacteria development around 78-80%. Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray (EDX) result also showed that sample successfully remineralized enamel surface. In addition, sample showed good pH, flavonoid, and polyphenol stability for 40 days.

  20. Evaluation of Microemulsion and Lamellar Liquid Crystalline Systems for Transdermal Zidovudine Delivery.

    Science.gov (United States)

    Carvalho, André Luis Menezes; Silva, José Alexsandro da; Lira, Ana Amélia Moreira; Conceição, Tamara Matos Freire; Nunes, Rogéria de Souza; de Albuquerque Junior, Ricardo Luiz Cavalcanti; Sarmento, Victor Hugo Vitorino; Leal, Leila Bastos; de Santana, Davi Pereira

    2016-07-01

    This study proposed to investigate and to compare colloidal carrier systems containing Zidovudine (3'-azido-3'-deoxythymidine) (AZT) for transdermal administration and optimization of antiretroviral therapy. Microemulsion (ME) and lamellar phase (LP) liquid crystal were obtained and selected from pseudoternary diagrams previously developed. Small-angle X-ray scattering and rheology analysis confirmed the presence of typical ME and liquid crystalline structures with lamellar arrangement, respectively. Both colloidal carrier systems, ME, and LP remained stable, homogeneous, and isotropic after AZT addition. In vitro permeation study (using pig ear skin) showed that the amount of permeated drug was higher for ME compared to the control and LP, obtaining a permeation enhancing effect on the order of approximately 2-fold (p drug permeation without causing apparent skin irritation. On the order hand, LP functioned as a drug reservoir reducing AZT partitioning into the skin. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  1. High-temperature nanoporous ceramic monolith prepared from a polymeric bicontinuous microemulsion template.

    Science.gov (United States)

    Jones, Brad H; Lodge, Timothy P

    2009-02-11

    Nanoporous ceramic with a unique pore structure was derived from an all-hydrocarbon polymeric bicontinuous microemulsion (BmuE). The BmuE was designed to allow facile removal of one phase, resulting in a nanoporous polymer monolith with BmuE-like structure. The pores were filled with a commercially available, polymeric precursor to nonoxide, Si-based ceramics. Pyrolysis resulted in a monolith of nanoporous ceramic, stable to at least 1000 degrees C, with a BmuE-like pore structure. The pore structure is disordered and 3-D continuous. Microscopy and gas sorption measurements suggest a well-defined pore size distribution spanning roughly 60-100 nm, sizes previously unattainable through related techniques.

  2. Capmul MCM/Solutol HS15-Based Microemulsion for Enhanced Oral Bioavailability of Rebamipide.

    Science.gov (United States)

    Kim, Ki Taek; Lee, Jae-Young; Park, Ju-Hwan; Cho, Hyun-Jong; Yoon, In-Soo; Kim, Dae-Duk

    2017-04-01

    Rebamipide (RBP) is a potent anti-ulcer and anti-oxidative agent, which is a BCS class IV drug with a low oral bioavailability of less than 10%. Thus, the systemic absorption of RBP into the blood circulation is an essential prerequisite for exerting its pharmacological activities after oral dosing. Herein, we report on microemulsion (ME) systems for the enhancement of oral RBP bioavailability. In this study, MEs consisting of Capmul MCM (oil), Solutol HS15 (surfactant), and ethanol (co-surfactant) were prepared by the construction of pseudo-ternary phase diagram. The RBP-loaded MEs had spherical nano-sized droplets with narrow size distribution and neutral zeta potential. Moreover, the prepared MEs significantly enhanced the dissolution and oral bioavailability of RBP with no discernible intestinal toxicity. These results suggest that the present ME system could be further developed as an alternative oral formulation for RBP.

  3. Interaction between droplets in a ternary microemulsion evaluated by the relative form factor method

    International Nuclear Information System (INIS)

    Nagao, Michihiro; Seto, Hideki; Yamada, Norifumi L.

    2007-01-01

    This paper describes the concentration dependence of the interaction between water droplets coated by a surfactant monolayer using the contrast variation small-angle neutron scattering technique. In the first part, we explain the idea of how to extract a relatively model free structure factor from the scattering data, which is called the relative form factor method. In the second part, the experimental results for the shape of the droplets (form factor) are described. In the third part the relatively model free structure factor is shown, and finally the concentration dependence of the interaction potential between droplets is discussed. The result indicates the validity of the relative form factor method, and the importance of the estimation of the model free structure factor to discuss the nature of structure formation in microemulsion systems

  4. The synthesis of PbF2 nanorods in a microemulsion system

    International Nuclear Information System (INIS)

    Xu Ke; Mao Changjie; Geng Jun; Zhu Junjie

    2007-01-01

    Single-crystalline PbF 2 nanorods with a diameter of 100-500 nm and length of 1-10 μm have been successfully synthesized by a simple sonochemical route in a microemulsion system at room temperature. The morphologies and structures of the nanorods were characterized by x-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, and high-resolution transmission electron microscopy. The experimental results showed that polyethylene glycol 6000 played an important role in the formation of PbF 2 nanorods. Room-temperature photoluminescence measurements indicated that the as-prepared PbF 2 nanorods had strong green emission, which could have potential applications in optoelectronic devices

  5. [Preparation of Oenothera biennis Oil Solid Lipid Nanoparticles Based on Microemulsion Technique].

    Science.gov (United States)

    Piao, Lin-mei; Jin, Yong; Cui, Yan-lin; Yin, Shou-yu

    2015-06-01

    To study the preparation of Oenothera biennis oil solid lipid nanoparticles and its quality evaluation. The solid lipid nanoparticles were prepared by microemulsion technique. The optimum condition was performed based on the orthogonal design to examine the entrapment efficiency, the mean diameter of the particles and so on. The optimal preparation of Oenothera biennis oil solid lipid nanoparticles was as follows: Oenothera biennis dosage 300 mg, glycerol monostearate-Oenothera biennis (2: 3), Oenothera biennis -RH/40/PEG-400 (1: 2), RH-40/PEG-400 (1: 2). The resulting nanoparticles average encapsulation efficiency was (89.89 ± 0.71)%, the average particle size was 44.43 ± 0.08 nm, and the Zeta potential was 64.72 ± 1.24 mV. The preparation process is simple, stable and feasible.

  6. Managing Reverse Logistics or Reversing Logistics Management?

    NARCIS (Netherlands)

    M.P. de Brito (Marisa)

    2004-01-01

    textabstractIn the past, supply chains were busy fine-tuning the logistics from raw material to the end customer. Today an increasing flow of products is going back in the chain. Thus, companies have to manage reverse logistics as well.This thesis contributes to a better understanding of reverse

  7. Improvement of effect of water-in-oil microemulsion as an oral delivery system for fexofenadine: in vitro and in vivo studies

    Directory of Open Access Journals (Sweden)

    Gundogdu E

    2011-08-01

    Full Text Available E Gundogdu1,2, I Gonzalez Alvarez3, E Karasulu1,21Faculty of Pharmacy, Department of Biopharmaceutics and Pharmacokinetics, 2Center For Drug Research and Development and Pharmacokinetic Applications, Ege University, Izmir, Turkey; 3Faculty of Pharmacy, Department of Engineering, Pharmaceutical Technical Section, Research Group on Drug Absorption, Universidad Miguel Hernández, Alicante, SpainAbstract: Fexofenadine (FEX has high solubility and low permeability (BCS, Class III. In this work, novel FEX loaded water in oil microemulsion (w/o was designed to improve bioavailability and compared with Fexofen® syrup in in vitro and in vivo studies. In addition, pharmacokinetic parameters in permeability studies were estimated by using WinNonLin software program. w/o microemulsion system was optimized using a pseudoternary phase diagram, composed of span 80/lutrol F 68 (9.5:0.5 w/w, oleic acide, isopropyl alcohol and water as surfactant mixture; oil and cosurfactant was developed for oral drug delivery. w/o microemulsion systems were characterized by phase behavior, particle size, viscosity and solubilization capacity. In vitro studies were studied using Caco-2 cell monolayer. Pharmacokinetic parameters of w/o microemulsion were investigated in rabbits and compared to Fexofen® syrup. Fexofen® syrup and microemulsion were administered by oral gavage at 6 mg/kg of the same concentration. The experimental results indicated that microemulsion (HLB = 5.53 formed nanometer sized droplets (33.29 ± 1.76 and had good physical stability. This microemulsion increased the oral bioavailability of FEX which was highly water-soluble but fairly impermeable. The relative bioavailability of FEX microemulsion was about 376.76% compared with commercial syrup in rabbits. In vitro experiments were further employed for the enhanced effect of the microemulsion for FEX. These results suggest that novel w/o microemulsion plays an important role in enhancing oral

  8. Synthesis and toxicity test of magnetic nanoparticle via biocompatible microemulsion system as template for application in targeted drug delivery

    Science.gov (United States)

    Kader, Razinah Abdul; Rose, Laili Che; Suhaimi, Hamdan; Manickam, Mariessa Soosai

    2017-09-01

    This work reports the preparation of magnetic nanoparticles (FeNPs) using biocompatible W/O microemulsion for biomedical applications. W/O microemulsion was formed using decane as oil phase, water, tween 80 as non-ionic surfactant and hexanol as organic solvent. The synthesized FeNPs were characterised by using Fourier Transform Infrared Resonance Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). The FTIR showed that Fe-O bond exist on 581cm-1 having strong magnetic strength whereas SEM showed the morphology surface of magnetic nanoparticles (FeNPs). Furthermore, analysis of XRD pattern magnetic nanoparticles (FeNPs) reveals a cubic iron oxide phase with good crystallize structure. Furthermore, toxicity test on human liver cells proved that it is 70% safe on human and proved to be a safety nanomedicine.

  9. Tubal Ligation Reversal

    Science.gov (United States)

    ... seal off the fallopian tubes, such as the Essure or Adiana systems, generally aren't reversible. Why ... electrocautery). Some types of sterilization, such as the Essure or Adiana systems, aren't considered reversible. Risks ...

  10. Enhanced effect and mechanism of water-in-oil microemulsion as an oral delivery system of hydroxysafflor yellow A

    OpenAIRE

    Qi, Jianping; Ping ,Qineng

    2011-01-01

    Jianping Qi1,2, Jie Zhuang1, Wei Wu2, Yi Lu2, Yunmei Song3, Zhetao Zhang1, Jia Jia1, Qineng Ping11School of Pharmacy, China Pharmaceutical University, Nanjing, People’s Republic of China; 2School of Pharmacy, Fudan University, Shanghai, People’s Republic of China; 3School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, AustraliaBackground: A microemulsion is an effective formulation for improving the oral bioavailability of poorly soluble drugs. ...

  11. Evaluation of local tolerance of the antiretroviral spermicide (WHI-07)-loaded gel-microemulsion in the porcine female reproductive tract.

    Science.gov (United States)

    D'Cruz, Osmond J; Uckun, Fatih M

    2008-04-01

    The local tolerance of the antiretroviral spermicide, WHI-07 (5-bromo-6-methoxy-5,6-dihydro-3'-azidothymidine-5'-(p-bromophenyl)-methoxyalaninyl phosphate)-loaded gel-microemulsion was evaluated in a physiologically relevant and sensitive porcine model. Gilts (Duroc) in nonestrus stages of the reproductive cycle received either a single or a daily intravaginal application of 2.0% WHI-07 via a gel-microemulsion for 6 days. Cervicovaginal lavage (CVL) fluid was obtained for up to 72 h after a single exposure and the cellular profile and levels of inflammatory cytokines (IL-1beta, IL-8, IFN-gamma and TNF-alpha) were quantitated by flow cytometry and chemiluminescence-based multiplex immunoassay, respectively. The reproductive tract (vagina, cervix, uteri and Fallopian tubes) harvested on day 7 was scored histologically for evidence of mucosal irritation using a new scoring criterion for ten histological endpoints that reflect pathological changes in the epithelial/ subepithelial and vascular/perivascular compartments. When compared with irritant reactions caused by the detergent-type spermicide, benzalkonium chloride (BZK), the scatter profile of CVL immune cells and basal levels of proinflammatory cytokines (IL-1beta, IL-8, IFN-gamma and TNF-alpha) in CVL fluid were unaffected by intravaginal exposure to 2% WHI-07. Unlike BZK, endpoint histology of the proximal and distal regions of the reproductive tract from gilts treated with 2.0% WHI-07 via gel-microemulsion for 6 days did not result in mucosal irritation or alteration in the epithelium, subepithelium/lamina propria, vessels/perivascular tissues and underlying/surrounding muscles. Based on surrogate markers for inflammation, leukocyte profile and histologic data for local tolerance, repeated intravaginal administration of WHI-07 via gel-microemulsion as a prophylactic contraceptive is unlikely to cause vaginal irritation.

  12. Electrical percolation in the presence of attractive interactions: An effective medium lattice approach applied to microemulsion systems

    Science.gov (United States)

    Hattori, Y.; Ushiki, H.; Engl, W.; Courbin, L.; Panizza, P.

    2005-08-01

    Within the framework of an effective medium approach and a mean-field approximation, we present a simple lattice model to treat electrical percolation in the presence of attractive interactions. We show that the percolation line depends on the magnitude of interactions. In 2 dimensions, the percolation line meets the binodal line at the critical point. A good qualitative agreement is observed with experimental results on a ternary AOT-based water-in-oil microemulsion system.

  13. Rapid analysis of caffeine in “smart drugs” and “energy drinks” by microemulsion electrokinetic chromatography (MEEKC)

    Czech Academy of Sciences Publication Activity Database

    Liotta, E.; Gottardo, R.; Seri, C.; Rimondo, C.; Mikšík, Ivan; Serpelloni, G.; Tagliaro, F.

    2012-01-01

    Roč. 220, 1-3 (2012), s. 279-283 ISSN 0379-0738 R&D Projects: GA ČR(CZ) GA203/08/1428 Institutional research plan: CEZ:AV0Z50110509 Institutional support: RVO:67985823 Keywords : caffeine * energy drink * smart drug * microemulsion electrokinetic chromatography Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 2.307, year: 2012

  14. 微乳液聚合法制备放射源%Preparation of Radioactive Source by Polymerization of Microemulsions

    Institute of Scientific and Technical Information of China (English)

    卢金辉; 李忠勇

    2015-01-01

    采用微乳液聚合方法制备放射源。选择甲基丙烯酸甲酯(MMA)/甲基丙烯酸羟乙酯(HEMA)/水(H 2 O)为微乳液体系,利用滴定法绘制三元相图,研究了温度与促进剂 N,N-二甲基对甲苯胺(DMT)对聚合的影响,利用 MMA(DMT)/HEMA/H 2 O 反向无皂微乳液聚合制备了99 Mo 和125 I 线源,并测定了放射源活度分布均匀性。结果表明,微乳液聚合是一种制备放射源的良好方法。%A new method for preparation of radioactive source by polymerization of microemulsions was introduced.Methyl methacrylate (MMA)/hydroxyethyl methylac-rylate (HEMA)/water (H 2 O)was selected as the microemulsions system.The ternary phase diagram was figured out by the conventional titration technique,and the influ-ences of temperature and N,N-dimethyl toluidine (DMT)as the accelerator on the polymerization were investigated.Then,line sources of 9 9 Mo and 1 2 5 I were obtained by polymerization of MMA (DMT)/HEMA/H 2 O soap-free inverse microemulsions,and the radioactivity distribution was measured.The results showed that preparation of radioactive source by polymerization of microemulsions was a good method.

  15. The addition of a pH-sensitive gel improves microemulsion stability for the targeted removal of colonic ammonia

    Directory of Open Access Journals (Sweden)

    Zhang Wen-Jun

    2011-05-01

    Full Text Available Abstract Background We prepared an oral W/O microemulsion for the removal of colonic ammonia (ME-RCA. The effect of this microemulsion was influenced by the digestion process in the gastrointestinal tract. In this paper, we aim to show that stability was improved by using a microemulsion-based gel for the removal of colonic ammonia (MBG-RCA. Methods MBG-RCA was prepared by adding sodium alginate to the ME-RCA. MBG-RCA and ME-RCA were passed through a simulated gastrointestinal environment, and the amount of colonic ammonia present was then determined by titration with a standard solution of hydrochloric acid. The pH of the gastrointestinal fluid was measured using a pH test paper and the size and form of the microemulsions were examined under the microscope. 18 healthy rats were randomly divided into three groups, fasted for 24 hours and allowed to drink normally. Three-way pipes were placed at the gastroduodenal junction in Group I, and at the terminal ileum in Group II. After the intragastric administration of ME-RCA, the stomach contents in Group I, the effluent from the terminal ileum in Group II and discharge from the anus in Group III were collected. The pH values of the gastrointestinal juice were measured by the pH test paper and those of the colon were determined by a universal indicator. These animal experiments were also used to test the effect of MBG-RCA. Results MBG-RCA showed a better removal rate of artificial colonic ammonia than ME-RCA (P Conclusions MBG-RCA was more stable in the gastrointestinal tract and more effective at removing colonic ammonia when a higher concentration of ammonia was present. This made it possible to achieve the targeted removal of colonic ammonia and is a promising method to prevent hepatic encephalopathy (HE in future studies.

  16. Enhanced biodegradation of lindane using oil-in-water bio-microemulsion stabilized by biosurfactant produced by a new yeast strain, Pseudozyma VITJzN01.

    Science.gov (United States)

    Abdul Salam, Jaseetha; Das, Nilanjana

    2013-11-28

    Organochlorine pesticide residues continue to remain as a major environmental threat worldwide. Lindane is an organochlorine pesticide widely used as an acaricide in medicine and agriculture. In the present study, a new lindane-degrading yeast strain, Pseudozyma VITJzN01, was identified as a copious producer of glycolipid biosurfactant. The glycolipid structure and type were elucidated by FTIR, NMR spectroscopy, and GC-MS analysis. The surface activity and stability of the glycolipid was analyzed. The glycolipids, characterized as mannosylerythritol lipids (MELs), exhibited excellent surface active properties and the surface tension of water was reduced to 29 mN/m. The glycolipid was stable over a wide range of pH, temperature, and salinity, showing a very low CMC of 25 mg/l. Bio-microemulsion of olive oil-in-water (O/W) was prepared using the purified biosurfactant without addition of any synthetic cosurfactants, for lindane solubilization and enhanced degradation assay in liquid and soil slurry. The O/W bio-microemulsions enhanced the solubility of lindane up to 40-folds. Degradation of lindane (700 mg/l) by VITJzN01 in liquid medium amended with bio-microemulsions was found to be enhanced by 36% in 2 days, compared with degradation in 12 days in the absence of bio-microemulsions. Lindane-spiked soil slurry incubated with bio-microemulsions also showed 20-40% enhanced degradation compared with the treatment with glycolipids or yeast alone. This is the first report on lindane degradation by Pseudozyma sp., and application of bio-microemulsions for enhanced lindane degradation. MEL-stabilized bio-microemulsions can serve as a potential tool for enhanced remediation of diverse lindanecontaminated environments.

  17. Microemulsion Using Polyoxyethylene Sorbitan Trioleate and its Usage for Skin Delivery of Resveratrol to Protect Skin against UV-Induced Damage.

    Science.gov (United States)

    Yutani, Reiko; Teraoka, Reiko; Kitagawa, Shuji

    2015-01-01

    We examined the phase behavior of various polyoxyethylene sorbitan fatty acid ester (polysorbates)/ethanol/isopropyl myristate (IPM)/150 mM NaCl solution (NaClaq) systems in order to prepare a microemulsion containing a low ratio of ethanol, which is more suitable for in vivo application. Using polyoxyethylene sorbitan trioleate (Tween 85), which has a large lipophilic moiety, as a surfactant component, single-phase domain of the phase diagram was the largest of all the polysorbates examined, and in particular a large oil-rich single-phase domain was obtained. When the ratio of Tween 85 to ethanol was changed from 1 : 1 to 3 : 1, the oil-rich single-phase domain further expanded, which led to a reduced ethanol concentration in the preparation. Thus, we determined the composition of the microemulsion to be Tween 85 : ethanol : IPM : NaClaq=30 : 10 : 53 : 7, and used it for skin delivery of resveratrol. Microemulsion gel was also prepared by adding 6.5% Aerosil) 200 into the microemulsion for ease of topical application. When applied with each vehicle, delivery of resveratrol into guinea pig skin in vitro was significantly enhanced compared with that by IPM, and resveratrol incorporated into the skin by microemulsion gel decreased lipid peroxidation to 29.5% compared with that of the control. Pretreatment of guinea pig dorsal skin with the microemulsion gel containing resveratrol almost completely prevented UV-B-induced erythema formation in vivo. These findings demonstrate that the microemulsion using Tween 85 containing a minimal concentration of ethanol enhanced the skin delivery of resveratrol and the incorporated resveratrol exhibited a protective effect against UV-induced oxidative damage.

  18. Preparation of Essential Oil-Based Microemulsions for Improving the Solubility, pH Stability, Photostability, and Skin Permeation of Quercetin.

    Science.gov (United States)

    Lv, Xia; Liu, Tiantian; Ma, Huipeng; Tian, Yan; Li, Lei; Li, Zhen; Gao, Meng; Zhang, Jianbin; Tang, Zeyao

    2017-11-01

    Quercetin can bring many benefits to skin based on its various bioactivities. However, the therapeutic effect of quercetin is limited due to the poor water solubility, pH instability, light instability, and skin permeation. The aim of the present work was applying essential oil-based microemulsions to improve the solubility, pH stability, photostability, and skin permeation of quercetin for topical application. Peppermint oil (PO-ME), clove oil (CO-ME), and rosemary oil (RMO-ME) were selected as model essential oils. Microemulsions composed of Cremophor EL/1,2-propanediol/essential oils (47:23:30, w/w) were selected as model formulations, based on the pseudo-ternary phase diagram and the characterizations. In the solubility study, the solubility of quercetin was improved dozens of times by microemulsions. Quercetin was found instable under alkaline condition, with 50% degraded in the solution of pH 13. However, PO-ME, CO-ME, and RMO-ME could protect quercetin from the hydroxide ions, with 47, 9, and 12% of quercetin degraded. In the photostability study, the essential oil-based microemulsions showed the capability of protecting quercetin from degradation under UV radiation. Where more than 67% of quercetin was degraded in aqueous solution, while less than 7% of quercetin degraded in microemulsions. At last, the in vitro skin permeation study showed that the essential oil-based microemulsions could enhance the permeation capacity of quercetin by 2.5-3 times compared to the aqueous solution. Hence, the prepared essential oil microemulsions could improve the solubility, pH stability, photostability, and skin permeation of quercetin, which will be beneficial for its topical application.

  19. Reverse logistics - a framework

    NARCIS (Netherlands)

    M.P. de Brito (Marisa); R. Dekker (Rommert)

    2002-01-01

    textabstractIn this paper we define and compare Reverse Logistics definitions. We start by giving an understanding framework of Reverse Logistics: the why-what-how. By this means, we put in context the driving forces for Reverse Logistics, a typology of return reasons, a classification of

  20. Constraining the reversing and non-reversing modes of the geodynamo. New insights from magnetostratigraphy.

    Science.gov (United States)

    Gallet, Y.; Pavlov, V.; Shatsillo, A.; Hulot, G.

    2015-12-01

    Constraining the evolution in the geomagnetic reversal frequency over hundreds of million years is not a trivial matter. Beyond the fact that there are long periods without reversals, known as superchrons, and periods with many reversals, the way the reversal frequency changes through time during reversing periods is still debated. A smooth evolution or a succession of stationary segments have both been suggested to account for the geomagnetic polarity time scale since the Middle-Late Jurassic. Sudden changes from a reversing mode to a non-reversing mode of the geodynamo may also well have happened, the switch between the two modes having then possibly been controlled by the thermal conditions at the core-mantle boundary. There is, nevertheless, a growing set of magnetostratigraphic data, which could help decipher a proper interpretation of the reversal history, in particular in the early Paleozoic and even during the Precambrian. Although yielding a fragmentary record, these data reveal the occurrence of both additional superchrons and periods characterized by extremely high, not to say extraordinary, magnetic reversal frequencies. In this talk, we will present a synthesis of these data, mainly obtained from Siberia, and discuss their implication for the magnetic reversal behavior over the past billion years.