Effects of Surface Relaxation on Enantiospecific Adsorption on Naturally Chiral Pt Surfaces

Many high Miller index metals surfaces are naturally chiral, offering opportunities for performing enantiospecific chemistry. Previous theoretical treatments of adsorption on these surfaces have used surfaces truncated from bulk crystals. This paper examines the effect of surface relaxation on enantiospecific adsorption on chiral Pt surfaces by using relaxed surface structures determined using density functional theory.     

Model algorithmic control of grade change operations in paper mills

In this work, the Model Algorithmic Control (MAC) method is applied to control the grade change operations in paper mills. The neural network model for the grade change operations is identified first and the impulse model is extracted from the neural network model. Results of simulations for MAC control of grade change operations are compared with plant operation data. The major contribution of the present work is the application of MAC in the industrial plants based on the identification of neural network models. We can confirm that the proposed MAC method exhibits faster responses and less oscillatory behavior compared to the plant operation data in the grade change operations.     

Case-based context ontology construction using fuzzy set theory for personalized service in a smart home environment

To provide context-based personalized services utilizing smart appliances in a smart home environment, we propose a framework for PersonAlized Service disCovery Using FuZZY-based CBR and Context Ontology (PASCUZZY). Basically, the PASCUZZY framework is implemented on case-based context ontology. To generate and manage the case instances on the case-based context ontology, we adopt the fuzzy set theory to transpose numerical-type context data sensed from the surrounding environment. The context is transposed to linguistic-type context instances on the context ontology. In addition, to formalize and manage the context and services as multi-attributed data, the context ontology was developed reflecting the structure of cases borrowed from case-based reasoning. Furthermore, we propose adaptation methods to adjust the generic fuzzy membership functions depending on the inhabitants’ context. It is performed by modifying the values of the membership number and/or modifying the numbers of the linguistic terms that are based on the inhabitants’ context to affect the membership numbers. The adapted membership functions return the personalized degree of memberships depending on the specialized context of a specific fuzzy variable. Inevitably, the number of cases on the case-based context ontology will be increased from time to time. We apply Ward’s method not only to reduce the search effort via a hierarchical clustering on the case-based context ontology but also to find the most similar service as a solution to the new context. To verify the superiority of the PASCUZZY framework, we perform two kinds of evaluations. First, we evaluate the effectiveness of the adaptation of the fuzzy membership functions. Second, we verify the effectiveness of the application of a clustering method to the case instances of the case-based context ontology to identify the most similar service. Results of the experiment verified the effectiveness and superiority of the PASCUZZY framework.     

Preparation and characterization of cellulose acetate organic/inorganic hybrid films

A series of organic/inorganic hybrid (OIH) films were prepared using cellulose acetate (CA) as the organic component and tetraethyl orthosilicate (TEOS) as the inorganic component. The chemical, morphological, and mechanical properties of these films were evaluated with a variety of analytical techniques. The results of these evaluations showed that crosslinked CA OIH films were formed during the sol-gel reactions. The structure of OIH films was very sensitive to the CA/TEOS ratio and film formation conditions. All of the films with added TEOS were two phase on a molecular level, i.e., inorganic TEOS domains surrounded by a CA matrix. Under some film formation conditions the presence of TEOS, a nonsolvent for CA, led to solvent/nonsolvent phase separation on the micron scale. © 1995 John Wiley & Sons, Inc.     

Adsorption of aroma chemicals on cotton fabric from aqueous systems

The adsorption of aroma chemicals on cotton fabric was studied relative to the surfactant concentration, surfactant type, water solubility, and fiber morphology. The adsorption increased with increasing surfactant concentration to a maximum near the critical micelle concentration, then decreased with further increases in surfactant concentration. The adsorption also was found to be highly dependent on the fiber surface area and pore structure; dramatic differences were observed between untreated and mercerized cotton fabric and are believed to be due to morphological differences. Cationic and anionic surfactants increased the aroma chemical adsorption, which varied with surfactant type, with cetyltrimethylammonium chloride (CTAC)>sodium dodecyl sulfate (SDS)>H₂O. Water solubility also influenced adsorption; in most cases, adsorption increased with water solubility. In addition, adsorption was also influenced by chemical structure and hydrophobic interactions. The adsorption of aroma chemicals on cotton fabric can be attributed to the aqueous solution being physically held in capillaries and pore structures within the fibular structure of cotton fiber and also to molecular interactions among the aroma chemical molecules, surfactants, and cotton substrate.     

Synthesis and luminescence properties of new blue‐light‐emitting polyconjugated poly{1,1′‐biphenyl‐4,4′‐diyl‐[1‐(4‐t‐butylphenyl)]vinylene} polymers and copolymers

Three new soluble polyconjugated polymers, all of which emitted blue light in photoluminescence and electroluminescence, were synthesized, and their luminescence properties were studied. The polymers were poly{1,1′‐biphenyl‐4,4′‐diyl‐[1‐(4‐t‐butylphenyl)]vinylene}, poly((9,9‐dioctylfluorene‐2,7‐diyl)‐alt‐{1,4‐phenylene‐[1‐(4‐t‐butylphenyl)vinylene‐1,4‐phenylene]}) [P(DOF‐PVP)], and poly([N‐(2‐ethyl) hexylcarbazole‐3,6‐diyl]‐alt‐{1,4‐phenylene‐[1‐(4‐t‐butylphenyl)]vinylene‐1,4‐phenylene}). The last two polymers had alternating sequences of the two structural units. Among the three polymers, P(DOF‐PVP) performed best in the light‐emitting diode devices of indium–tin oxide/poly(ethylenedioxythiophene) doped with poly(styrene sulfonate) (30 nm)/polymer (150 nm)/Li:Al (100 nm). This might have been correlated with the balance in and magnitude of the mobility of the charge carriers, that is, positive holes and electrons, and also the electronic structure, that is, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels, of the polymers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 307–317, 2006     

Thermotropic phase properties of the hydroxyceramide/cholesterol system

The interaction of cholesterol with ceramides containing α-hydroxy fatty acyl chains (hydroxyceramides) has been studies as a foundation for characterizing the lipid bilayers of thestratum corneum. A relatively large quantity of cerebrosides was obtained from bovine brain and converted to ceramides through removal of the carbohydrate side chain. The ceramides were separated based on the absence or presence of hydroxy fatty acyl chains. The lyophilized hydroxyceramides showed a broad melting region at 92°C. Hydroxyceramides dispersed in water produced a relatively narrow, thermotropic transition at 75°C. The effect of cholesterol on this thermotropic phase transition of hydroxyceramides was determined by differential scanning calorimetry. With respect to the main transition, cholesterol caused a broadening of the phase transition at relatively low levels as well as a decrease in the peak transition temperature. The presence of cholesterol at levels in excess of 7 wt% gave rise to an additional low-temperature transition at 55°C. Upon immediate rescanning, this transition was exothermic, but with increasing incubation time the area under the excess heat capacity curve as a function of temperature became smaller. After two days or more, the transition observed was endothermic. At cholesterol levels between 40 and 50 wt%, multiple peaks were observed. From comparisons with related systems, the cooperative thermal transitions of hydroxyceramides with cholesterol are suggested to result from changes in hydrogen bonding or be due to phase separation. The composition of isolated brain ceramides is being compared with that reported for thestratum corneum.     

Polyurethane‐infiltrated carbon foams: A coupling of thermal and mechanical properties

The thermal and mechanical properties of polyurethane‐infiltrated carbon foam of various densities were investigated. By combining the high thermal conductivity of the carbon foam with the mechanical toughness of the pure polyurethane, a mechanically tough composite (relative to the unfilled foam) that could be used at higher temperatures than the polyurethane's degradation was formed. Both the tensile strength and the modulus increased by an order of magnitude for the composites compared to unfilled foam, while the compressive and shear strengths and moduli of the composites approached values exhibited by pure polyurethane. At both 300 and 400°C, the rectangular blocks of pure polyurethane lost their mechanical integrity due to decomposition in air. Thermogravimetric analysis confirms substantial initial weight loss above 290°C. Filled carbon foam blocks, however, maintain their mechanical integrity at both 300 and 400°C indefinitely, although the bulk of the rectangular block mass is polyurethane. Three different carbon foam densities are examined. As expected, the higher density foams show greater heat transfer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2348–2355, 2003     

Synthesis and characterizations of a polyimide containing a triphenylamine derivative as an interlayer in polymer light-emitting diode

Polyimide containing triphenylamine derivative (TPD-PI) was synthesized to prepare a polymer interlayer having insolubility in common nonpolar solvent for light-emitting polymers. N,N′-diphenyl-N,N′-bis(4-aminophenyl)-1,1-biphenyl-4,4′-diamine, as a new triphenylamine-containing diamine monomer, was synthesized by the palladium-catalyzed amination reaction between 4-nitrodiphenylamine and 4,4′-dibromobiphenyl and subsequent reduction of the nitro-intermediate. The TPD-PI was prepared from the synthesized diamine monomer and 4,4′-(hexafluoropropylidene)-diphthalic anhydride by the standard two-step polymerization method, which involved ring-opening polymerization and subsequent cyclodehydration. The structures and properties of the monomer and the resulting polyimide were characterized with ¹H and ¹³C NMR, elemental analysis, gel permeation chromatography, UV-visible spectroscopy, etc. The TPD-PI is readily soluble in aprotic polar solvents such as N-methyl-2-pyrrolidinone and N,N-dimethylformamide and insoluble in nonpolar solvents such as toluene and xylene. The highest occupied molecular orbital (HOMO) level of the TPD-PI was measured to be 5.5 eV by a photoelectron spectrometer in air, and the band gap was calculated as 3.1 eV from the onset of UV-vis spectrum. The polymer light-emitting diode with the thin TPD-PI layer between a hole injection layer and an emitting polymer layer was fabricated to examine the performance of the polyimide as an polymer interlayer. Although the luminous efficiency of the device is lowered by the introduction of the TPD-PI interlayer, the lifetime of the device is improved.