New Organic Sensitizer for Stable Dye-Sensitized Solar Cells with Solvent-Free Ionic Liquid Electrolytes

We report a high molar extinction coefficient metal-free sensitizer composed of a triarylamine donor in combination with the 2-(2,2'-bithiophen-5-yl)acrylonitrile conjugation unit and cyanoacrylic acid as an acceptor. In conjugation with a volatile acetonitrile-based electrolyte or a solvent-free ionic liquid electrolyte, we have fabricated efficient dye-sensitized solar cells showing a corresponding 7.5% or 6.1% efficiency measured under the air mass 1.5 global sunlight. The ionic liquid cell exhibits excellent stability during a 1000 h accelerated test under the light-soaking and thermal dual stress. Intensity-modulated photocurrent and photovolatge spectroscopies were employed along with the transient photoelectrical decay measurements to detail the electron transport in the mesoporous titania films filled with these two electrolytes.

Effect of immersion in various media on the sorption, solubility, elution of unreacted monomers, and flexural properties of two model dental composite compositions

Immersion in various media has different effect on the properties of dental composites, such as sorption, solubility, elution of unreacted monomers, flexural strength, and flexural elastic modulus. In the present work, the effect of immersion in various media and the relationship between the variation of these properties and the components of dental composite were investigated.

Lattice Boltzmann study of hydrodynamic effects in lamellar ordering process of two-dimensional quenched block copolymers

By incorporating self-consistent field theory with lattice Boltzmann method, a model for polymer melts is proposed. Compared with models based on Ginzburg-Landau free energy, our model does not employ phenomenological free energies to describe systems and can consider the chain topological details of polymers. We use this model to study the effects of hydrodynamic interactions on the dynamics of microphase separation for block copolymers. In the early stage of phase separation, an exponential growth predicted by Cahn-Hilliard treatment is found. Simulation results also show that the effect of hydrodynamic interactions can be neglected in the early stage.

Reversed micelle formation in a model liquid-liquid extraction system

The formation of reversed micelles and the roles of extractant and extracted complexes were investigated in the Cyanex923/n-heptane/H2SO4 system. Interfacial tension (gamma), electrical conductivity (kappa), and water content measurements showed that Cyanex923 had a tendency to self-assemble, forming reversed micelles. The changes in electrical conductivity with concentration of H2SO4 in the organic phase (CH2SO4,(0)) exhibited an S-type curve: a correlation was found between the change in electrical conductivity and the water content as a function of CH2SO4,(0),.

Defect evolution and hydrodynamic effects in lamellar ordering process of two-dimensional quenched block copolymers

The effects of hydrodynamic interactions on the lamellar ordering process for two-dimensional quenched block copolymers in the presence of extended defects and the topological defect evolutions in lamellar ordering process are numerically investigated by means of a model based on lattice Boltzmann method and self-consistent field theory. By observing the evolution of the average size of domains, it is found that the domain growth is faster with stronger hydrodynamic effects. The morphological patterns formed also appear different. To study the defect evolution, a defect density is defined and is used to explore the defect evolutions in lamellar ordering process. Our simulation results show that the hydrodynamics effects can reduce the density of defects. With our model, the relations between the Flory-Huggins interaction parameter chi, the length of the polymer chains N, and the defect evolutions are studied.

NMR titration and molecular model MOPAC calculation of protonation processes of two MRI ligands

The protonation process of two DTPA bis(amide) derivatives, DTPA-BDMA and DTPA-BDEA, was studied by using H-1 NMR titration and MOPAC calculation. Their protonation process was proposed in the order of the central amine, the terminal amines, the central carboxyl, the terminal carboxyl, the other terminal carboxyl and central amine. During the protonation of the terminal amine, there existed a large fraction of proton transfer from the central amine to the other terminal amine.

Synthesis and properties of two series of H-bonded and non-H-bonded thermotropic liquid crystal monomers

Two series of monomers, namely n-1-bromo-(4-(4-nitrophenylazo)phenyloxy]alkanes (Bn, n = 2, 3, 4, 5, 6, 8, 10) and N-n-[4-(4-nitrophenylazo)phenyloxy]alkyl diethanolamines (Cn, n = 3, 5, 6, 10), were synthesized and characterized. Their thermal behaviour was studied by differential scanning calorimetry (DSC), wide angle X-ray diffractometry (WAXD) and polarizing optical microscopy (POM) equipped with a hot stage. The results showed that the Bns (n greater than or equal to 6) exhibit monotropic nematic liquid crystalline behaviour; no liquid crystalline phase was found for the Bns (n < 6), while for the Cns, enantiotropic smectic liquid crystallinity for n = 5, 6, 10 was seen, and for n = 3 monotropic smectic phases were found. This different phase behaviour between Bn and Cn compounds is attributed to their different end groups. The FTIR analysis of Cn indicated that there exists an intermolecular hydrogen bond between hydroxy groups, so that more stable liquid crystalline phase are formed. The effect of the length of the flexible chain on the thermal behaviour is also discussed.

Bilayer formation of two chiral ferroelectric liquid crystal molecules at the air-water interface

The bilayer formation behavior of two chiral ferroelectric liquid crystal molecules at the air-water interface was studied.

ELECTRON-DIFFRACTION STUDY ON MONOLAYER LB FILMS OF LIQUID-CRYSTALLINE POLYACRYLATE CONTAINING PARA-NITRO AZOBENZENE

Monolayers of liquid-crystalline polyacrylate containing para-nitro azobenzene (HP6) on the water subphase were characterized by the surface pressure (pi)-area per monomer unit (A) isotherm and were successfully transferred onto glass substrates by the vertical lifting method. The monolayer Langmuis-Blodgett (LB) films transferred at different surface pressures were studied by electron diffraction. The thickness of the monolayer LB film was measured by the transmission electron microscopy folding method. The results of the electron diffraction of the monolayer LB films of HP6 showed that a two-dimensional arrangement exists in the transferred films. According to the results of the pi-A isotherm, electron diffraction and the measured thickness of the monolayer LB film, a molecular arrangement model of HP6 on the water subphase was proposed. The ordered monolayer formation of HP6 showed it to be promising as a second-order non-linear optical material.

Total analytical method for Radix astragali extract using two-binary multi-segment gradient elution liquid chromatography

There is an urgent need for thorough analysis of Radix astragali, a widely used Chinese herb, for quality control purposes. This paper describes the development of a total analytical method for Radix astragali extract, a multi-component complex mixture. Twenty-four components were separated step by step from the extract using a series of isocratic isopropanol-methanol elutions, and then 42 components were separated similarly using methanol-water elutions. Based on the log k(w) and -S of the 66 components obtained from the above procedure and the optimization software developed in our laboratory, an optimum elution program consisting of seven methanol-water segments and four isopropanol-methanol segments was developed to finish the task of analyzing the total components in a single run. Under optimized gradient conditions, the sample of Radix astragali extract was analyzed. As expected, most of the components were well separated and the experimental chromatogram was in a good agreement with the predicted one.

Drug-protein interaction studied by technique of microdialysis combined with high performance liquid chromatography

Drug-protein binding is an important process in determining the activity and fate of a pharmaceutical agent once it has entered the body. This review examines the method of microdialysis combined with high-performance liquid chromatography (HPLC) that has been developed;by ours to study such interactions, in which the microdialysis was applied to sample the free drug in the mixed solution of drug with protein, and HPLC to quantify the concentration of free drug in the microdialysate. This technique has successfully been used for determining various types of binding interactions between the low affinity drugs, high affinity drugs and enantiomers to HSA. For the case of competitive binding of two drugs to a protein in solution, a displacement equation has been derived and examined with four nonsteroidal anti-inflammatory drugs and HSA as model drugs and protein, respectively. Microdialysis with HPLC was adopted to determine simultaneously the free solute and displacing agent in drug-protein solutions. The method is able to locate the binding site and determine affinity constants even up to 10(7) L/mol accurately.

Deconvolution of overlapped peaks based on the exponentially modified Gaussian model in comprehensive two-dimensional gas chromatography

Comprehensive two-dimensional gas chromatography (GC x GC) has attracted much attention for the analys is of complex samples. Even with a large peak capacity in GC x GC, peak overlapping is often met. In this paper, a new method was developed to resolve overlapped peaks based on the mass conservation and the exponentially modified Gaussian (EMG) model. Linear relationships between the calculated sigma, tau of primary peaks with the corresponding retention time (t(R)) were obtained, and the correlation coefficients were over 0.99. Based on such relationships, the elution profile of each compound in overlapped peaks could be simulated, even for the peak never separated on the second-dimension. The proposed method has proven to offer more accurate peak area than the general data processing method. (c) 2005 Elsevier B.V. All rights reserved.

Theranostic applications of fluorescent liquid crystalline nanoparticles

Lipid liquid crystalline nanoparticles can find application as nanocarriers in several fields of the daily life but, very likely, the pharmaceutical arena is the most relevant. Indeed, several problems encountered in drugs administration (e.g. critical sideeffects from antitumor drugs) require alternative, less invasive, but simultaneously efficient therapeutic routes to be explored. Novel fields of personalized nanomedicine are developing in this direction. One of the most interesting is theranostic, which calls for the design of platforms capable of combining therapeutic and diagnostic functionalities. In this optic, we explored the potential of monoolein-based cubosomes and hexosomes as nanocarriers for theranostic purposes. Our work focussed on the design of lipid nanoparticles able to deliver antineoplastic drugs and imaging probes for fluorescent optical in vitro and in vivo imaging. We developed cubosome formulations loaded with antineoplastic drugs and useful for the fluorescence imaging of cells. Such formulations were also actively targeted to cancer cells and coupled with a NIR-emitting fluorophore, which was the promise for in vivo applications. We also investigated hexosomes with encouraging results encapsulating in their lipid matrix a BODIPY derivative with solvatochromic properties, helpful for the understanding of the dye localization. Importantly, we reported (manuscript submitted) the first proof-of-principle for in vivo fluorescence optical imaging application using monoolein-based cubosomes in a healthy mouse animal model. Finally, since relatively little is known about the interaction of cubosomes with biological systems, their effects on lipid droplets, mitochondria and lipid profile of HeLa cells were deeply studied. This thesis is divided in two main parts. The introduction section reports on the essential background of the research field, and it is followed by the publications (published or submitted) resulting from these three years of work.

Topological changes in a two-dimensional foam cluster

Cox, S.J., Vaz, M.F. and Weaire, D. (2003) Topological changes in a two-dimensional foam cluster. The European Physical Journal E - Soft Matter . 11:29-35.

Steady drainage in emulsions: corrections for surface Plateau borders and a model for high aqueous volume fraction

Peron, N., Cox, S.J., Hutzler, S. and Weaire, D. (2007) Steady drainage in emulsions: corrections for surface Plateau borders and a model for high aqueous volume fraction. The European Physical Journal E - Soft Matter. 22: 341-351. Sponsorship: This research was supported by the European Space Agency (14914/02/NL/SH, 14308/00/NL/SG) (AO-99-031) CCN 002 MAP Project AO-99-075) and Science Foundation Ireland (RFP 05/RFP/PHY0016). SJC acknowledges support from EPSRC (EP/D071127/1).