Orientational orders in binary mixtures of hard HGO molecules

studied liquid crystal phases of binary mixtures of non-spherical molecules. The components of the mixtures are two kinds of hard Gaussian overlap (HGO) molecules, one kind of molecules with a small molecular-elongation parameter (small HGO molecules) cannot form stable liquid crystal phase in bulk, and other with a large elongation parameter (large HGO molecules) can form liquid crystal phase easily. In the mixtures, like the large HGO molecules, the small HGO molecules can also form an orientation-ordered phase, which is because that the large HGO molecules can form complex confining surfaces to induce the alignment of the small molecules and generate an isotropic-anisotropic phase transition in the whole binary mixtures. We also study the transition on different mixtures composed of small and large HGO molecules with different elongations and different concentrations of the large molecules. The obtained result implies that small anisotropic molecules might show liquid crystal behavior in confinement.Comment: 5 pages, 3 figure

Orientational orders of small anisotropic molecules confined in slit pores

We have studied phase behavior of hard gaussian overlap molecules with small anisotropic parameter confined in two plane parallel structureless hard walls. Our investigation based on standard constant-NPT Monte Carlo molecular simulation led us to some interesting findings. For small anisotropic molecules the nematic phase is instable in bulk, while, if the distance between the walls is small enough, an orientation-ordered phase can form. This result indicates that the required molecular elongation forming liquid-crystal phases is smaller in confinement than that in bulk. Considering the value of the elongation of molecules, the computed result inplies that small molecule liquid crystals may exist in confinement.Comment: 5 pages, 7 figure

Heat Conduction and Long-Range Spatial Correlation in 1D Models

Heat conduction in one-dimensional (1D) systems is studied based on an analytical S-matrix method, which is developed in the mesoscopic electronic transport theory and molecular dynamic (MD) simulations. It is found that heat conduction in these systems is related to spatial correlation of particle motions. Randomizations of scatterers is found to break the correlation, hence results in normal thermal conduction. Our MD simulations are in agreement with the theoretical expectations. The results are useful for an understanding of the relation between heat conduction and dynamic instablities or other random behavior in 1D systems.Comment: 7 pages, 4 figure

Vertical orientation with a narrow distribution of helical peptides immobilized on a quartz substrate by stereocomplex formation

Second-harmonic generation (SHG) of a donor–π–acceptor (D–π–A) chromophore attached to helical peptides was used for the evaluation of the self-assembled monolayer (SAM) structure of a stereocomplex of helical peptides. A stereocomplex SAM of a left-handed helical conjugate (D17) and a right-handed helical conjugate (L17) showed an SHG intensity four times larger than a stereocomplex SAM of a left-handed helical D17 and a right-handed helical peptide without the D–π–A chromophore (LA16), which agrees well with dependence of SHG intensities on the surface densities of the D–π–A chromophore. The SHG intensities of enantiopure SAMs of D17 and L17 are, however, 47% and 27% of the stereocomplex SAM of D17 and L17, respectively. These differences can be explained only after taking a larger distribution of the tilt angle of the chromophore in the enantiopure SAMs than in the stereocomplex SAM of D17 and L17. On the basis of these analyses, it is concluded that the stereocomplex SAM of a left-handed helix and a right-handed helix constitutes a well-ordered structure, where the tilt angle of the helical peptide from the surface normal becomes small with a narrow distribution due to stereocomplex formation

Probing of Transient Electric Field Distribution in ITO/PI/P3HT/Au By Time-Resolved Optical Second Harmonic Generation Measurement

AbstractBy using time-resolved optical second harmonic generation (TR-SHG) measurements, we studied carrier behaviors in poly(3-hexylthiophene) (P3HT) metal-insulator-semiconductor (MIS) diodes. TR-SHG measurements probed transients of electric fielddistribution in the P3HT active layer. Results showed that hole injection and removal processes were non-reversal, where the response times were different from each other and the relaxation time of the transient electric field strongly depended on the hole injection process

Dynamic disorder in receptor-ligand forced dissociation experiments

Recently experiments showed that some biological noncovalent bonds increase their lifetimes when they are stretched by an external force, and their lifetimes will decrease when the force increases further. Several specific quantitative models have been proposed to explain the intriguing transitions from the "catch-bond" to the "slip-bond". Different from the previous efforts, in this work we propose that the dynamic disorder of the force-dependent dissociation rate can account for the counterintuitive behaviors of the bonds. A Gaussian stochastic rate model is used to quantitatively describe the transitions observed recently in the single bond P-selctin glycoprotein ligand 1(PSGL-1)$-$P-selectin force rupture experiment [Marshall, {\it et al.}, (2003) Nature {\bf 423}, 190-193]. Our model agrees well to the experimental data. We conclude that the catch bonds could arise from the stronger positive correlation between the height of the intrinsic energy barrier and the distance from the bound state to the barrier; classical pathway scenario or {\it a priori} catch bond assumption is not essential.Comment: 4 pages, 2 figure

Correlation between 18F-fluorodeoxyglucose Positron Emission Tomography/computed Tomography and Clinicopathological Features in Invasive Ductal Carcinoma of the Breast

We evaluated the usefulness of preoperative 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) examinations to predict the pathological features in primary breast cancer. In particular, we evaluated the correlation between the maximum standardized uptake values (SUVmax) obtained by 18F-FDG PET/CT and the Ki67 expression in estrogen receptor (ER)-positive invasive ductal carcinoma (IDC). Primary IDC patients operated between March 2009 and July 2013 at Okayama University Hospital were enrolled. We evaluated the correlations between the SUVmax and age, postoperative pT, histological grade, lymph vascular invasion, status of hormone receptor, human epidermal growth factor receptor 2 (HER2), Ki67 expression and node status. The Ki67 expression was classified as high (>14%) versus low (<14%). We enrolled 138 patients with IDC. Their median SUVmax was 3.85 (range:0-52.57). In a univariate analysis, the SUVmax was significantly related to age, pT, histological grade, lymphovascular invasion, hormone receptor status, HER2 status, node status and Ki67. In the 113 patients with ER-positive IDC, there was a significant correlation between Ki67 and SUVmax (p=0.0030). The preoperative 18F-FDG PET/CT results of IDC patients had significant relationships with pathological status parameters. The determination of the preoperative SUVmax might help classify Luminal A and Luminal B patients among luminal-type breast cancer patients

UV- ozone treated graphene oxide/ PEDOT:PSS bilayer as a novel hole transport layer in highly efficient and stable organic solar cells

The utilization of UV-ozone (UVO) treated graphene oxide (GO)/PEDOT:PSS bilayer as hole transport layer (HTL) in solution processed organic solar cells (OSCs) is demonstrated. The HTLs were treated with UVO for 0, 5, 10 and 15 min. The 10 min treated OSC showed the best performance and displayed power conversion efficiency (PCE) of 5.24%, much higher than the untreated OSC device. This enhanced performance is mainly driven by improvements in the short circuit current (∼10.82 mA/cm2) as well as the fill factor (∼57%) that is ascribed to the moderate reduction of GO and increased work function (WF) of PEDOT:PSS after UVO treatment, which improved the contact conditions between the HTL and photoactive layer. Consequently, extraction efficiency of the photogenerated holes is increased, while recombination probability of holes and electrons in the photoactive layer is decreased. Moreover, the UVO-reduction of GO and consequently increased conductivity of reduced-GO (r-GO) has been modeled and proved using the density functional theory (DFT) simulation. Meanwhile, the 15 min UVO-treated OSC device showed severe reduction in the PCE that dropped to 2.11%, possibly due to couple of factors such as decomposition of chemical bonds, significant increase in the series resistance and pronounced drop in the photovoltaic performance parameters