New SmCG phases in a hydrogen-bonded bent-core liquid crystal featuring a branched siloxane terminal group

In this study, we synthesized three analogous bent-core molecules, a hydrogen-bonded complex and a covalent-bonded compound with branched siloxane units (H-SiO and C-SiO, respectively) and a hydrogen-bonded complex with an alkyl unit (H-Alk), and investigated the effects of the hydrogen bonding and branched siloxane terminal units on their mesomorphic properties. The covalent-bonded compound C-SiO and the hydrogen-bonded complex H-Alk exhibited typical SmCP phases; in contrast, the hydrogen-bonded complex H-SiO exhibited a series of general tilt smectic (SmCG) phases with highly ordered layer structures (i.e., SmC?G(2)P(F)-USmCG(2)P(A)-SmCG(2)P(F)-SmCGP(F) upon cooling). During the SmCG-type phase transition process, a 2D-modulated ribbon structure transferred into highly ordered layers via undulated layers, as the hydrogen-bonding strength increased with reduced temperatures. As the SmCG domains were aligned under dc electric fields, a gradual decrease in the leaning angle from ca. 60° to 50° (while the tilt angle kept at ca. 31°) could be determined by in situ wide-angle X-ray scattering (WAXS). Combined with Fourier transform infrared and Raman spectroscopic data, our results suggest that the change in the leaning angle was governed by the competition of the hydrogen bonds and microsegregation of siloxane units within the bilayer structure of the hydrogen-bonded complex H-SiO. In addition, the ferroelectric-(antiferroelectric)-ferroelectric transitions proven by the switching current responses in the SmCG-type phases of H-SiO reveal that the polar switching occurred through collective rotations around the long axis of H-SiO. Therefore, novel SmCG phases with a series of highly ordered 2D-structures were induced by the effects of the hydrogen bonding and branched terminal siloxane unit in the bent-core hydrogen-bonded LC complex H-SiO.     

Microscopic modeling and control logic for incident-responsive automatic vehicle movements in single-automated-lane highway systems

Automatic response to lane-blocking incidents is a critical issue in the field of automated highway systems (AHS). Accordingly, this paper presents a microscopic vehicular control methodology for automatic-control (AC) vehicular movements in response to lane-blocking incidents in the AHS environment. The embedded traffic control logic is based on the basic safety requirements for automatic-control lane traffic maneuvers responding to lane-blocking incidents in the single-automated-lane AHS environment. Accordingly, respective automated vehicular control models are proposed to deal with AC vehicles moving in three corresponding sequential phases, i.e., (1) AC platoon approaching the incident site from the blocked lane, (2) mandatory lane changing and mixed car following in the adjacent lane, and (3) AC platoon reforming downstream from the incident site in the blocked automated lane. Using a microscopic simulation model which embeds these proposed models, preliminary tests are conducted to investigate the relative performance of the proposed method in various traffic flow and control scenarios. The resulting numerical results, including simplified sensitivity analyses, indicate that the proposed microscopic traffic control logic permits regulating automatic-control vehicular movements in response to the effects of lane-blocking incidents on traffic flows either in control-free lanes or in the automatic-control lanes. Implications of the results and some findings are discussed for further research.     

Adsorption and nucleation on smooth surfaces

The nucleation and growth of condensate nuclei on smooth surfaces, e.g., an immiscible liquid or a smooth solid, can occur both by the direct addition of molecules from the vapor and from those adsorbed on the substrate. We show how to generalize nucleation theory to allow for the simultaneous occurrence of both mechanisms. The vapor-condensate-substrate interfacial forces, the contact angle, the critical supersaturation, and the coefficient in the adsorption isotherm are different ways of expressing the affinity between vapor molecules and the substrate surface. The critical supersaturations for nucleation on the surface of an immiscible liquid and nucleation on the surface of a perfectly smooth solid are predicted in terms of these parameters and the relationships among them. For most values of these parameters we find that adsorbed molecules are usually far more important to the nucleation process than those in the vapor phase.     

Spectrophotometric determination of a thiobarbituric acid-reactive substance in human hair.

A simple and sensitive spectrophotometric method for the determination of a thiobarbituric acid-reactive substance (TBARS) in human hair has been developed. The proposed method is based on the formation of a red-colored product by the reaction of products of lipid peroxidation with thiobarbituric acid in an acidic medium. The absorbance of the resulting red product was measured at 534 nm. The linear dynamic range was between 1.0 and 20 micromol/L. The recoveries were 98.3-105.0%, and the relative standard deviations (RSD) were 0.32-1.24, respectively. TBARS in digested hair sample was stable for 3 days at room temperature. It was found that, using this method, the hair TBARS concentration in smokers (0.116 +/- 0.030 micromol/g, n = 30) was significantly higher than that in non-smokers (0.096 +/- 0.015 micromol/g, n = 30) (p < 0.05).     

A fuzzy clustering approach to real-time demand-responsive bus dispatching control

Quick response (QR) to passenger needs is a key objective for advanced public transportation systems (APTS), and it has become increasingly important for contemporary metropolitan bus operations to gain a competitive advantage over private transportation. This paper presents a real-time control methodology for demand-responsive bus operations that respond quickly to passenger needs. The proposed method primarily involves two levels of functionality: (1) short-term forecasting of passenger demands using time-series prediction models, and (2) identification of service strategies coupled with the associated bus service segments using fuzzy clustering technologies in response to variances in passenger demand attributes and traffic conditions. The proposed bus operations method identifies the demand-responsive vehicle service strategies primarily according to the predicted up-to-date attributes of passengers’ demands, rather than deterministic passenger arrival rates, which were generally used in previous literature. In addition, the variation of traffic conditions along bus lines is considered in the proposed method. Results from numerical studies using real data of passengers’ demands, including passenger volume at each bus stop and the passenger origin-destination (O-D) patterns, are presented to demonstrate the effectiveness of the proposed method for real-world applications.     

Quantization of the PoissonSU(2) and its Poisson homogeneous space — The 2-sphere

We show that deformation quantizations of the Poisson structures on the Poisson Lie groupSU(2) and its homogeneous space, the 2-sphere, are compatible with Woronowicz's deformation quantization ofSU(2)'s group structure and Podles' deformation quantization of 2-sphere's homogeneous structure, respectively. So in a certain sense the multiplicativity of the Lie Poisson structure onSU(2) at the classical level is preserved under quantization.With an Appendix by Jiang-Hua Lu and Alan Weinstein Department of Mathematics, University of California, Berkely, CA 94720 USAPartially supported by NSF-Grant DMS-8505550     

Differential Games of inf-sup Type and Isaacs Equations

Motivated by the work of Fleming, we provide a general framework to associate inf-sup type values with the Isaacs equations. We show that upper and lower bounds for the generators of inf-sup type are upper and lower Hamiltonians, respectively. In particular, the lower (resp. upper) bound corresponds to the progressive (resp. strictly progressive) strategy. By the Dynamic Programming Principle and identification of the generator, we can prove that the inf-sup type game is characterized as the unique viscosity solution of the Isaacs equation. We also discuss the Isaacs equation with a Hamiltonian of a convex combination between the lower and upper Hamiltonians.     

Semiconducting tellurium-iron-copper carbonyl polymers

The unprecedented ternary Te-Fe-Cu chain polymers [{Et4N}{TeFe3(CO)9Cu}]infinity and [{TeFe3(CO)9Cu2}(mu-4,4'-dipyridyl)1.5]infinity were prepared from the self-assembly of [Et4N]2[TeFe3(CO)9] with [Cu(MeCN)4][BF4] in THF or in the presence of 4,4'-dipyridyl in THF. These two chain polymers, which can also be constructed from the precursor complex TeFe3(CO)9Cu2(MeCN)2, show semiconducting behaviors with low band gaps of 0.59 and 0.41 eV, respectively. In addition, their conductivity and the effect of the bridging ligand are further elucidated by theoretical calculations.