Prediction of Aphasia Severity in Patients with Stroke Using Diffusion Tensor Imaging.

This study classified the severity of aphasia through the Western Aphasia Battery and determined the optimal cut-off value for each Language-Related White Matter fiber and their combinations, we further examined the correlations between Language-Related White Matter and Western Aphasia Battery subscores. This retrospective study recruited 64 patients with aphasia. Mild/moderate and severe aphasia were classified according to cut-off Aphasia Quotient score of 51 points. Diffusion tensor imaging and fractional anisotropy reconstructed Language-Related White Matter in multiple fasciculi. We determined the area under the covariate-adjusted receiver operating characteristic curve to evaluate the accuracy of predicting aphasia severity. The optimal fractional-anisotropy cut-off values for the individual fibers of the Language-Related White Matter and their combinations were determined. Their correlations with Western Aphasia Battery subscores were analyzed. The arcuate and superior longitudinal fasciculi showed fair accuracy, the inferior frontal occipital fasciculus poor accuracy, and their combinations fair accuracy. Correlations between Language-Related White Matter parameters and Western Aphasia Battery subscores were found between the arcuate, superior longitudinal, and inferior frontal occipital fasciculi and spontaneous speech, auditory verbal comprehension, repetition, and naming. Diffusion-tensor-imaging-based language-Related White Matter analysis may help predict the severity of language impairment in patients with aphasia following stroke.

Fabrications of electrospun nanofibers containing inorganic fillers for dye-sensitized solar cells.

Poly(vinylidenefluoride-co-hexafluoropropylene) (PVDF-HFP) nanofibers containing inorganic fillers were fabricated by electrospinning. Dye-sensitized solar cells (DSSCs) using these nanofibers showed improved short circuit currents without degraded fill factors or open circuit voltages. The long-term stabilities of cells using electrospun PVDF-HFP/titanium isopropoxide (TIP) nanofibers were significantly improved.

Photovoltaic and thermal properties of electrolytes based on electrospun poly(vinylidene fluoride-hexafluoro propylene)/poly(methyl methacrylate) nanofibers for dye-sensitized solar cells.

We prepared electrospun polymer nanofibers by electrospnning method and investigated about their applications to dye-sensitized solar cells (DSSCs). Electrospun polymer nanofibers applied to the polymer matrix in electrolyte for DSSCs. To improve the stiffness of polymer nanofiber, poly(vinylidene fluoride-hexafluoro propylene)/Poly(methyl methacrylate) (PVDF-HFP/PMMA) blend nanofibers were prepared and examined. In the electrospun PVDF-HFP/PMMA (1:1) blend nanofibers, the best results of VOC, JSC, FF, and efficiency of the DSSC devices showed 0.71 V, 12.8 mA/cm2, 0.61, and 5.56% under AM 1.5 illumination.

Development of dye-sensitized solar cells composed of liquid crystal embedded, electrospun poly(vinylidene fluoride-co-hexafluoropropylene) nanofibers as polymer gel electrolytes.

In order to overcome the problems associated with the use of liquid electrolytes in dye-sensitized solar cells (DSSCs), a new system composed of liquid crystal embedded, polymer electrolytes has been developed. For this purpose, three types of DSSCs have been fabricated. The cells contain electrospun poly(vinylidene fluoride-co-hexafluoropropylene) (e-PVdF-co-HFP) polymer gel electrolyte, with and without doping with the liquid crystal E7 and with a liquid electrolyte. The morphologies of the newly prepared DSSCs were explored using field emission scanning electron microscopy (FE-SEM). Analysis of the FE-SEM images indicate that the DSSC composed of E7 embedded on e-PVdF-co-HFP polymer gel electrolyte has a greatly regular morphology with an average diameter. The ionic conductivity of E7 embedded on e-PVdF-co-HFP polymer gel electrolyte was found to be 2.9 × 10(-3) S/cm at room temperature, a value that is 37% higher than that of e-PVdF-co-HFP polymer gel electrolyte. The DCCS containing the E7 embedded, e-PVdF-co-HFP polymer gel electrolyte was observed to possess a much higher power conversion efficiency (PCE = 6.82%) than that of an e-PVdF-co-HFP nanofiber (6.35%). In addition, DSSCs parameters of the E7 embedded, e-PVdF-co-HFP polymer gel electrolyte (V(oc) = 0.72 V, J(sc) = 14.62 mA/cm(2), FF = 64.8%, and PCE = 6.82% at 1 sun intensity) are comparable to those of a liquid electrolyte (V(oc) = 0.75 V, J(sc) = 14.71 mA/cm(2), FF = 64.9%, and PCE = 7.17%, both at a 1 sun intensity).

Preparation and characterization of acrylated-SiO2@TiO2 hollow hybrid nanospheres.

Novel inorganic-organic hybrid hollow nanospheres, acrylated SiO2 and SiO2@TiO2, were synthesized via a sol-gel polymerization, using crown-appended sugar gelator 1 as an organic template for the unique nanospherical structures in demand for a fast expanding area in nanomaterial research. In this work, hollow SiO2 nanospheres were obtained by a simple sol-gel method followed by calcination and rather rough TiO2 nanolayers were coated onto the highly dispersed surface of SiO2 nanospheres and further copolymerization of MPA on the surface of SiO2 and SiO2@TiO2 nanosphseres was successfully conducted. The morphological properties of those hollow nanospheres were characterized by TEM, SEM and powder-XRD. Furthermore, the physical and chemical properties of the synthesized nanocomposites were characterized by the analysis of EDX, FT-IR, TGA and ESCA.

Chiral molecular arrangement behaviour of unsymmetrical sugar-based gelators by introduction of steroisomeric alanine moiety.

We have newly synthesized unsymmetrical D-sugar-based hydrogelators, which have either D-alanine (1) or L-alanine (2) moieties and their chiral molecular arrangements were characterized by TEM, powder-XRD, CD and FT-IR spectroscope. The D-sugar-based hydrogelator, which contained D-alanine, showed remarkably slow chiral molecular packing by intermolecular hydrogen bonding interaction in gel formation. Hydrogelator 1 possesses the orthorhombic perpendicular (O(perpendicular)) subcell type according to the wide-angle region of the XRD pattern and the CH2 scissoring band delta(CH2) in the IR spectrum. On the other hand, hydrogel 2, which contained the D-sugar, but L-alanine, did not undergo the chiral molecular arrangement.

Miscibility and hydrolytic behavior of poly(trimethylene carbonate) and poly(L-lactide) and their blends in monolayers at the air/water interface.

In this study, two biodegradable polymers, poly(trimethylene carbonate) (PTMC) and poly(L-lactide) (PLLA) along with a series of PTMC/PLLA blends, were used as spreading materials to form LB monolayers at the air/water interface to study hydrolytic reaction kinetics of the monolayers with the Langmuir film balance technique. The pi-A isotherms of each homopolymer and their blends showed that blends of PTMC and PLLA were miscible on the neutral subphase (pH 7.4), whereas there was evidence of phase separation on the basic subphase (pH 10.7). The hydrolysis behavior of each homopolymer was investigated at these two different pH conditions. The PTMC monolayer showed faster hydrolysis on the neutral subphase (pH 7.4) than on the basic subphase (pH 10.7). However, in the case of the PLLA monolayer, the hydrolysis on the basic subphase is faster than that on the neutral subphase. On the basis of this result, hydrolysis mechanisms of PTMC and PLLA, considering a general hydrolysis mechanism and their stereo structures, are proposed. The hydrolysis rates of blends of PTMC and PLLA were much faster than that of each homopolymer on the basic subphase (pH 10.7). This result, which can be explained by a "dilution effect", was supported by the structure based mechanism proposed here.

Interfacial degradation of biodegradable polyester monolayers at the air/enzyme-containing water interface.

The initial enzymatic degradation behavior of Langmuir monolayer films of a series of biodegradable polyesters at a constant surface pressure was investigated at the air/water interface. The initial degradation of polyester monolayers strongly depended on the structural formula of the polyesters. By the co-polymerization of 3-hydroxyvalerate (3HV) into the poly[(R)-3-hydroxybutyrate] backbone, the critical surface pressure at which the degradation occurs was increased and the rate of enzymatic degradation was retarded because of the inactivity of the enzyme and the hydrophobicity of 3HV. The decrease in the optical purity of poly(l-lactide) (PLLA) delayed the time when the degradation occurred at a constant surface pressure. However, the degradation rate after the critical time was accelerated as the optical purity decreased. These results can be explained by the mutual competition of the preferential degradation of l-lactide units and the density.

Dye-sensitized solar cells using polymer electrolytes based on poly(vinylidene fluoride-hexafluoro propylene) nanofibers by electrospinning method.

The dye-sensitized solar cell (DSSC) devices using polymer electrolytes based on electrospun poly(vinylidene fluoride-hexafluoro propylene) (PVDF-HFP) nanofibers were fabricated and investigated the photovoltaic performances. The electrospun PVDF-HFP nanofibers were prepared by various parameters such as; polymer concentrations, applied voltages, and tip to collector distances (TCD) by the electrospinning method. The open circuit voltage (V(OC)), short circuit current (J(SC)), fill factor (FF), and overall power conversion efficiency (eta) of DSSC devices using electro-spun PVDF-HFP nanofibers were 0.7180-0.7420 V, 9.7200-10.8837 mA/cm2, 0.5610-0.6250, and 4.1700-5.0186%, respectively. When 15 wt% of polymer concentration, 14 kV of applied voltage, and 14 cm of TCD is applied to fabricate the PVDF-HFP nanofiber, the electrospun PVDF-HFP nanofiber should be the regular diameter of a nanofiber, the power conversion efficiency of the DSSC device reached 5.0186% as the best result.

Synthesis, characterization, and photovoltaic properties of soluble TiOPc derivatives.

We have synthesized soluble TiOPc derivatives containing alkoxy groups for use as additives in dye-sensitized solar cells (DSSCs). The DSSC devices containing these TiOPc derivatives exhibited short-circuit current densities of 8.49~10.04 mA/cm(2) and power conversion efficiencies of 2.73~3.62 % under AM 1.5 illumination and 100 mW/cm(2) irradiation.