Search

A dye-doped LC/polymer light shutter with a polymer structure that is formed using the thermally-induced phase separation (TIPS) method is demonstrated. The TIPS method does not include any chemical reaction, and thus there is no degradation of the dye during the fabrication process. The light shutter can be fabricated quickly because the optical performance is not affected by the cooling time. The fabricated TIPS cell exhibits excellent optical performance, such as a low haze value of 0.5% in the initial transparent state, and a high haze value of 99.1% in the opaque state with a superior black color. This approach can be used for the high image quality of see-through displays using organic light-emitting diodes.

A polarization model which accounts for electric field-induced charge transfer between fullerene molecules is introduced. Application of this model to the C60 dimer and trimer shows that intermolecular charge transfer makes a significant contribution to the polarizabilities of these clusters. This polarization model is incorporated into a one-electron Hamiltonian for describing non-valence correlation-bound anions, allowing us to further demonstrate that intermolecular charge transfer also results in increased stability of these anion states.

In this paper, we propose a new statistical corner model for the precise variation analysis of CMOS logic gate delay. The conventional corner model includes pessimism in its prediction of delay variation as a result of inadequate statistical consideration of device characteristics. Therefore, to develop an accurate delay corner model, we analytically derive corner modeling targets for device characteristics, which are statistically shrunk when considering the variation and the correlation of transistor and parasitic resistance and capacitance ( RC ). Then, the derived targets are obtained by multiplying the conventional corner parameters using the newly proposed corner scaling factors. Simulation results verify that the corner model fitted to the proposed targets accurately predicts the three standard deviation limits of delay variation. To implement the parasitic RC aware delay corner in compact models of the process design kit, an artificial neural network is used to model the complex relationship between the parasitic RC and the delay corner model. The delay variations predicted by the proposed model match well with the Monte Carlo simulation results at various simulation conditions, unlike the conventional corner model, which introduces pessimism.

In this paper, we present the effects of curing temperature on switching between the transparent and translucent states in a polymer-stabilized liquid-crystal (PSLC) cell. When cured at a low temperature, polymer structures are formed without disturbing the initial alignment of LCs so that haze in the transparent state is dramatically reduced. Moreover, we can achieve very fast switching between the haze-free transparent and high-haze translucent states because there is a little degradation in the performance of the transparent and translucent states when the polymer concentration is increased. We demonstrated an ON–OFF response time of less than 3 ms and a gray-to-gray response time of less than 6 ms in a PSLC cell.

The adsorption, formation, and interaction energies between carbon dioxide (CO2) and carbon oxide functional groups on porous carbon surface were analyzed through XPS, textural analysis, CO2 gas adsorption, and theoretical study. Carbon molecular sieves (CMSs) as porous carbon were modified by several concentrations of hydrogen peroxide (H2O2) solution under atmospheric conditions in an attempt to introduce carbon oxide groups and increase their CO2 adsorption capacity. Created oxide groups on carbon surface of CMSs were determined by XPS analysis and the CO2 adsorption capacities were investigated through the CO2 adsorption isotherms at 273 and 298 K at low pressure (max. 800 mmHg). The CO2 uptake capacity on CMSs modified by H2O2 was increased compared to an unmodified CMS and increased with increasing carboxylic (-COOH) group concentration on the carbon surface of CMSs. For a theoretical approach, binding energies between CO2 and various functional groups on the surface of CMSs have been investigated using several electronic structure calculations. As the result of the computational study by the MP2 method, a carboxylic group has the highest binding energy for CO2 (-COOH····CO2) of 4.45 kcal/mol, compared to quinone (dbndO) of 3.9, phenol (-OH) of 3.2 and lactone (-O-C=O) of 3.57 kcal/mol. This work demonstrates that introducing -COOH groups on CMS by H2O2 are a suitable modification for CO2 adsorption.

We report control of the haze value in a liquid crystal (LC) cell driven by a fringe electric field. When a fringe field is applied to a vertically aligned (VA) cell, a large spatial phase differen...

In this paper, we present a diffractive liquid crystal (LC) device capable of rapid switching between the transparent and translucent states for window display applications. In contrast to previously reported LC light shutters based on light scattering, the proposed LC device relies on diffraction of white incident light by an electric field-induced periodic continuous LC profile. It can be switched between the transparent and translucent states without a complicated driving scheme or a polymer structure. This device exhibits outstanding features for window display applications, such as a high transparency and a wide viewing angle in the transparent state, a low operating voltage, and a short response time.

We report a simple method for reducing the response time of homogeneously aligned liquid crystal (LC) cells by using two-dimensional confinement of the LCs. We have shown that the switching speed can be increased by serval fold in in-plane switching and fringe-field switching cells by introducing interdigitated electrodes parallel to the LC alignment direction. We also report an interdigitated pixel electrode structure with alternating tilts for a much wider viewing angle by aligning the LCs without a pretilt. In addition to a short response time and wide viewing angle, this device allows a much larger deviation of the LC alignment direction which is essential for mass production. Moreover, LCs with negative dielectric anisotropy can be used to minimize the transmittance decrease.

The effects of water vapor on the catalytic activity of a Fe-BEA catalyst in the NH 3 -SCR reaction for N 2 O and NO were investigated using diffusive reflectance infrared Fourier transform spectroscopy (DRIFTS) tests and SCC-DFTB calculation. It was found that water vapor only decreased the N 2 O conversion rate and did not affect the conversion rates of NO. The DRIFTS analysis revealed that the presence of water increased the adsorption strength of nitrous oxide (N 2 O) on the catalyst surface. On the other hand, nitric oxide (NO) conversion route was only altered from NO 2 -SCR to standard selective catalytic reduction (SCR) upon injection of water vapor. It was confirmed that the water vapor not only inhibited the desorption of N 2 O during the reduction step but also induced stronger adsorption of N 2 O during the NH 3 -SCR reaction. A computational chemical model that includes hydroxyl zeolite, N 2 O, and NO supported the experimental result showing binding force between the hydroxyl zeolite and N 2 O is much higher than that between hydroxyl zeolite and NO. It is believed that the stronger adsorption induced by water vapor caused delayed dissociation of N 2 O thereby not allowing for catalytic conversion.

A polarization model which accounts for electric field-induced charge transfer between fullerene molecules is introduced. Application of this model to the C60 dimer and trimer shows that intermolecular charge transfer makes a significant contribution to the polarizabilities of these clusters. This polarization model is incorporated into a one-electron Hamiltonian for describing non-valence correlation-bound anions, allowing us to further demonstrate that intermolecular charge transfer also results in increased stability of these anion states.

The effects of the interplay between pressure and surface chemistry on the transformation of few-layer graphene into an sp 3 -bonded carbon film were investigated with first-principles density functional theory calculations including ab initio molecular dynamics. N 2 H 4 , H 2 O, and He were each considered as a candidate pressure medium. Compared with the bulk graphite, the surface chemistry overwhelmingly governed the conversion energetics for nanometer-thick graphene layers. A hydrogen-donating medium reduced the required conversion pressure compared with an inert one; the conversion pressure obtained by using N 2 H 4 was 40% of the corresponding pressure obtained with He. We suggest that pressurizing the cell through hydrogen-donating pressure media has the advantage from the surface chemistry by concentrating hydrogen atoms on carbon surfaces.

Low-frequency driving of a liquid crystal display (LCD) panel to minimise power consumption has drawn much attention recently. In case an LCD panel is driven by a low-frequency fringe field, image flickering phenomenon is detected by the naked human eye when the sign of the applied electric field is reversed. We investigated the effect of electrode spacing on the image flickering phenomenon induced by the flexoelectric effect in a fringe-field-switching (FFS) liquid crystal cell. We found that the image flicker in an FFS cell under low-frequency driving can be eliminated in a simple manner by changing the electrode spacing.

Natural triterpenoids are of great interest to researchers of various fields as they possess diverse physicochemical and biological properties. In medicinal chemistry, detailed information about the chemical structures of bioactive triterpenoids often helps find new lead compounds. Herein, the low-energy structures of (20S)-protopanaxadiol and (20S)-protopanaxatriol, the aglycones of various triterpenoid saponins found in Panax ginseng, and their (20R)-epimers have been predicted by the geometry optimization of the conformers extracted from molecular dynamics simulations with the self-consistent-charge density functional tight-binding method. By performing quantum mechanical calculations on the low-energy conformers, we have estimated the NMR chemical shifts of the compounds, which display good agreement with the most recently reported experimental values within an expected range of errors. Our results indicate that theoretical estimation of the NMR parameters of a relatively large molecule with a molecular mass of 500 is feasible. Copyright © 2015 John Wiley & Sons, Ltd.

We report a method for fast gray-to-gray (GTG) switching of a homogeneously aligned liquid crystal (LC) cell. Homogeneously aligned LCs are instantly vertically aligned by applying a vertical electric field for a short period of time before switching to a target gray level. Once the LCs are vertically aligned, we apply an in-plane voltage higher than the data voltage that corresponds to a target gray level, while maintaining the vertical electric field. Then, at the time the vertical field is removed, we apply a data voltage required for switching to the target gray level. We experimentally demonstrate GTG switching of a homogeneously aligned LC cell at a low temperature (-20°C), which is 7.5 times faster than a fringe-field switching (FFS) cell at the same temperature, which is comparable to the switching speed of a fringe-field switching cell at room temperature (23°C).

We propose a method for fast grey-to-grey (GTG) switching of a homogeneously aligned liquid crystal (LC) cell. Homogeneously aligned LCs are instantly vertically aligned by applying a vertical electric field for a short time before switching to a target grey level. Once the LCs are vertically aligned, we apply an in-plane voltage higher than the data voltage that corresponds to a target grey level, while maintaining the vertical electric field. Then, at the time the vertical field is removed, we apply a data voltage required for switching to the target grey level. We experimentally demonstrated GTG switching of a homogeneously aligned LC cell, which is 11 times faster than a fringe-field switching cell.

Scaling factors have been applied to the estimation of the spectroscopic constants of pure isotopologues of two polyatomic molecules: ammonia (NH 3 ) and formaldehyde (HCHO). Vibrational frequencies and rotational constants of four isotopologues of each molecule have been calculated using the resolution-of-the-identity second-order coupled cluster (RICC2) and coupled cluster singles and doubles (CCSD) methods with the aug-cc-pVDZ and aug-cc-pVTZ basis sets. It has been observed that the scaling factors for the vibrational frequencies and rotational constants of the isotopologues are dependent on the isotopic mass. With the given scaling factors calculated at the CCSD/aug-cc-pVTZ level of theory, the experimental spectroscopic data are reproduced with an error range of 0.6% for the D 13 CD 16 O isotopologue. In addition, the spectrum of H 13 CH 16 O is accurately predicted with the scaling factors calculated from the other isotopologues. The estimated spectrum is in good agreement with the experimental spectrum.

Recently, we reported n-type graphene can be achieved simply using H2 molecules. It was understood by the attachment of hydrogen atoms dissociated on the surface of graphene. However, the amount of attached hydrogen has not been yet investigated. Here, we show the possibility of the formation of C H bonds due to the H2 exposure theoretically and the mass of the attached hydrogen atoms on graphene experimentally. The amount of the attached hydrogen atoms has been measured by a quartz crystal microbalance (QCM). After exposure of a multilayer graphene (MLG) to 20 bar of H2 pressure at 353 K for 20 h, the resonance frequency (RF) of QCM decreased. It indicates that the mass of the MLG increases. On the basis of the RF variation, we concluded that the hydrogen atoms were bonded to 3.84% of carbon atoms in the MLG. In order to confirm the C H bonding of MLG, Raman spectroscopy was performed before and after exposure to H2 pressure. On exposure, the D peak developed and the peak for 2-D graphite in 2D band increased. The experimental results and theoretical calculation demonstrate that the H2 molecules on the surface of the graphene are dissociated and that some of dissociated H atoms are attached on graphene.

The like-charge ion pairings of hydronium and hydroxide were investigated using both ab initio cluster calculations and QM/MM-MD aqueous simulations. While only a two-water-bridged H3O(+)(H2O)2H3O(+) is found in hydronium cluster calculations, three clusters of HO(-)(H2O)2HO(-), HO(-)(H2O)3HO(-) and HO(-)(H2O)4HO(-) are stable dihydroxide aggregates. In addition, an interesting yet very stable parallelogram structure of [O-H···H-O](2-) without any bridging water was also discovered using QM/MM-MD simulations. According to our analysis, its unique structure reduces the electrostatic repulsion and allows stable coordination with solvents at the same time. In conclusion, hydroxide can form stronger like-ion pairs than hydronium in aqueous solution mostly due to its versatile coordination ability with solvents.

We investigated the two-dimensional (2D) confinement effect on the switching of vertically-aligned negative liquid crystals (LCs) by an electric field applied between the top and bottom patterned electrodes. When an electric field is applied to a patterned vertical alignment (PVA) cell, virtual walls form in the middle of the gaps between and at the center of the patterned electrodes. These virtual walls formed in a PVA cell results in the turn-off time being dependent on the pitch of the patterned electrodes as well as the cell gap. We found that a short response time can be achieved by the fine patterning of pixel electrodes with little decrease in the transmittance. The obtained numerical results agree well with the model based on the 2D confinement effect of LCs.

In this paper, we propose a method for sub- millisecond switching of hybrid-aligned nematic liquid crystals (LCs). The LCs are switched to the bright state through downward tilting and twist deformation initiated by applying an in-plane electric field, whereas they are switched back to the initial dark state through optically hidden relaxation initiated by applying a vertical electric field for a short duration. Using the proposed device, we experimentally obtained a total response time of 0.75 ms .

This report introduces Gaussian electrostatic models (GEMs) to account for charge penetration effects in water−water interactions, allowing electrostatic interactions to be accurately described. Three different Gaussian electrostatic models, GEM-3S, GEM-5S, and GEM-6S are designed with s-type Gaussian functions. The coefficients and exponents of the Gaussian functions are optimized using the electrostatic potential (ESP) fitting procedure based on that of the MP2/aug-cc-pVTZ method. The electrostatic energies of ten different water dimers that were calculated with GEM-6S agree well with the results of symmetry-adapted perturbation theory (SAPT), indicating that this designed model can be effectively applied to future water models.

We propose a method for fast switching of vertically aligned (VA) negative liquid crystals (LCs) by hiding the relaxation process of LCs. During the turn-off process, a strong in-plane electric fie...

We present a method to eliminate the image flicker effect in a fringe-field switching liquid crystal display by doping a small amount of bent-core liquid crystal (BLC) molecules. We found that, by adding 2.0 wt% of BLC, the transmittance during positive and negative frames could be balanced and the image flicker was eliminated. At the same time, both the transmittance and response time were also improved.

Summary Background Ischemic preconditioning (IPC) is a powerful mechanism for limiting myocardial infarction during or after ischemia–reperfusion (IR) injury. However, effective target genes and proteins for IPC are unknown. We characterized global changes in gene expression in the heart during IR, and identified effective target genes for IPC. Methods Hearts were isolated from Sprague-Dawley rats under control, IR, and IPC conditions. We generated expressed-sequence-tags (ESTs) for each group and investigated their functions and the major biological processes in which they are involved using the eukaryotic clusters of orthologous groups (KOG) database and bioinformatics analysis tools. Results IR modified the expression of 126 genes. Of these, 62 were upregulated, 64 were downregulated, and 77 were found to be effective target genes for IPC. In KOG analysis, most of the genes whose expression was modified were involved in energy production and conversion and the cytoskeleton. A gene-to-gene interaction map revealed that IR modified the expression of genes in four major functional modules: electron transport chain/oxidative phosphorylation; tricarboxylic acid cycle/glucose metabolism/amino acid metabolism; cellular structure and contraction; and gene transcription, translation, and protein folding. At the individual gene level, the genes encoding mitochondrial cytochrome c oxidase subunits 2 and 3 were downregulated, and those encoding the major cytoskeleton components tropomyosin, myosin light chain, myomesin 2, and myosin regulatory light chain 2, as well as the gene encoding the iron-storage protein ferritin, were upregulated, and thus were identified as potential target genes. Real time PCR evaluated expression patterns of three mitochondrial IPC effective genes. Two-dimensional electrophoresis proteomic analyses revealed altered expression of 14 target proteins. The expression patterns of six proteins matched the corresponding EST expression patterns. Conclusion The global profiling of cardiac ischemia-related genes provides the possible mechanisms of IR and IPC and ways of treating IR injury.

In this research, a multi-stage cold forging process for a spring guide pin of stamping die set is designed through alternative process for sustainable production. Highly energy and material consuming process needs to be converted to an energy saving process. Up to now, a spring guide pin for stamping die set is usually manufactured by machining process in order to achieve dimensional accuracy. However, machining process has some disadvantages such as excessive material loss, low productivity, and poor mechanical properties. In order to overcome these problems, a multi-stage cold forging process is applied to manufacturing spring guide pin for achieving less material loss and higher productivity. Multi-stage forging process requires careful design steps to prevent the defects of the final product. So, the design must consider the material flow during the whole process and the loading limit of the press in order to avoid product defects such as folding and underfilling. To develop multi-stage forging process for spring guide pin the forming load and material flow at each step is analyzed using a commercial finite element code, DEFORM. The guide pin is then manufactured by the developed multistage forging process, and is compared to the simulation results. Also the efficiency of the developed forging process is compared to the machining process. The developed process is a green manufacturing process minimizing material loss, which achieves cost reduction through improved material usage and productivity compared to the more widely used machining process.

In this paper we introduce drive schemes for sub-millisecond switching of a liquid crystal display panel using a three-terminal electrode structure. By applying a vertical trigger pulse method, we obtained the turn-off switching time of 0.52 ms without any decrease of transmittance. By applying a vertical bias field, we obtained the total response time of 0.70 ms.

Local minima and first-order saddle points on the potential energy surface of the ( H 2 O ) 6 - cluster as described by a recently introduced one-electron model Hamiltonian are located using a combination of the basin-hopping Monte Carlo, doubly-nudged elastic band, and eigenvector-following methods. The minimum energy pathways connecting the transition states and minima are identified and used to construct disconnectivity diagrams. The implications of the calculated rearrangement pathways for experimental studies of ( H 2 O ) 6 - are discussed.

Resonant two-photon ionization (R2PI), UV hole-burning (UVHB), and resonant ion-dip infrared (RIDIR) spectroscopy have been used to study the single-conformation infrared and ultraviolet spectroscopy of 3-(4-hydroxyphenyl)-N-benzylpropionamide (HNBPA, HOC6H5CH2CH2(CO)NHCH2C6H5) cooled in a supersonic expansion. UVHB determines the presence of three conformers, two of which dominate the spectrum. RIDIR spectra in the OH stretch (3600-3700 cm(-1)), amide NH stretch (3450-3500 cm(-1)), and CO stretch (1700-1750 cm(-1)) regions reveal the presence of small shifts in these fundamentals that are characteristic of the folding of the flexible chain and the ring-ring and ring-chain interactions. On the basis of a comparison of the experimental frequency shifts with calculations, the two major experimentally observed conformers are assigned to two folded structures in which the two aromatic rings are (nominally) face-to-face and perpendicular to one another. The perpendicular structure has a transition assignable to the S0-S2 origin, while the face-to-face structure does not, consistent with a faster nonradiative process in the latter case. The calculated structures and vibrational frequencies are quite sensitive to the level of theory due to the flexibility of the interconnecting chain and the importance of dispersive interactions between the two aromatic rings.

A key factor for realising an Internet-based virtual manufacturing system (VMS) and virtual enterprise (VE) is how to represent the manufacturing elements and process mechanics precisely and effectively. This paper presents methods to represent the motion paths and operation of CNC machine tools on the Web. The method is composed of: 1. Geometrical modelling of the machine tools. 2. Kinematic modelling of the movements of machine tools. 3. Representation of the developed model in the internet infrastructure. 4. Development of a prototype Web-based virtual machine tools (WVMT). WVMT is available on the internet URL http://wvmt. post-ech.ac.kr, by which the client can interactively operate CNC machine tools, and verify the part program via graphic simulation.

Purpose To examine the role of epithelial cells in inducing the differentiation of keratocytes into myofibroblasts and to determine whether this effect may be inhibited by amniotic membrane matrix. Methods In vivo, a 9-mm diameter, partial-thickness corneal flap was created in 12 rabbit eyes (6 rabbits), which were equally subdivided into three groups. The first group was implanted with one layer of a 6-mm diameter human amniotic membrane, from which the epithelium had been removed by dispase. The second group received an implantation of dispase-treated amniotic membrane with cultured rabbit corneal epithelial cells. The third group received the same implantation as the second group except that the cultured corneal epithelial cells were sandwiched between two layers of membrane. All corneas were removed 2 weeks later and were subjected to Masson trichrome staining and immunofluorescence staining with monoclonal antibodies to alpha-smooth muscle (alpha-SM) actin for myofibroblasts and cytokeratins for epithelial cells. In vitro collagen gels impregnated with different types of human ocular surface fibroblasts were seeded with or without rabbit corneal epithelial cells before testing for gel contraction. Results Positive staining of alpha-SM actin was noted only in keratocytes adjacent to corneal epithelial cells at the incision site and those grown on the basement membrane side of the amniotic membrane. Negative staining was noted when epithelial cells were removed by dispase or when cultured corneal epithelial cells were sandwiched between two layers of membrane. Gel contraction by fibroblasts was significantly promoted when epithelial cells were seeded on the gel. In the latter situation, positive staining of alpha-SM actin was noted in fibroblasts subjacent to epithelial cells but not in those impregnated in the gel. Conclusion Epithelial cells are capable of inducing the differentiation of adjacent fibroblasts into myofibroblasts; such an induction requires a close epithelial-mesenchymal contact. Amniotic membrane alone does not induce this effect and can help block such induction by epithelial cells.

A radio-frequency equivalent circuit model for the symmetric vertical natural capacitor (VNCAP) in a 45 nm low-standby-power CMOS process is presented. The average effective capacitance density of 2.24 fF/ mum2 is obtained from VNCAPs of 1 times (M1 - M5) + 2 times (M6 - M7) metal-layer configuration after the open-short de-embedding procedure. The proposed model consists of main series capacitance network and lossy substrate network. The accuracy of the VNCAP model is verified S-parameters, effective capacitance Ceff, and quality factor (Q) up to 15 GHz. The proposed model can accurately describe the frequency characteristics of S-parameters, Ceff, and Q-factor up to 15 GHz for VNCAPs with different widths and lengths.