Solitary and compact-like shear waves in the bulk of solids

We show that a model proposed by Rubin, Rosenau, and Gottlieb [J. Appl. Phys. 77 (1995) 4054], for dispersion caused by an inherent material characteristic length, belongs to the class of simple materials. Therefore, it is possible to generalize the idea of Rubin, Rosenau, and Gottlieb to include a wide range of material models, from nonlinear elasticity to turbulence. Using this insight, we are able to fine-tune nonlinear and dispersive effects in the theory of nonlinear elasticity in order to generate pulse solitary waves and also bulk travelling waves with compact support

Actively controllable topological phase transition in phononic beam systems

Topological insulators, which allow edge or interface waves but forbid bulk waves, have revolutionized our scientific cognition of acoustic/elastic systems. Due to their nontrivial topological characteristics, edge (interface)waves are topologically protected against defects and disorders. This superior and unique characteristic could lead to a wealth of new opportunities in applications of quantum and acoustic/elastic information processing. However, current acoustic/elastic topological insulators are still at an infancy stage where the theory and prediction only work in laboratories and there are still many problems left open before promoting their practical applications. One of the apparent disadvantages is their narrow working frequency range, which is the main concern in this paper. We design a one-dimensional phononic beam system made of a homogeneous epoxy central beam sandwiched by two homogeneous piezoelectric beams, and covered with extremely thin electrodes, periodically and separately placed. These electrodes are connected to external electric circuits with negative capacitors. We show that a topological phase transition can be induced and tuned by changing the values of the negative capacitors. It follows that the working frequency of the topologically protected interface mode can be widely changed, such that the working frequency range of the topological insulator can be considerably `broadened'. This intelligent topological device may also find wide applications in intelligent technologies that need controllable information processing of high precision

Bend and splay elastic constants of a discotic nematic

We report the dielectric constants and the splay and bend elastic constants of hexan-dodecanoyloxy truxene in the nematic phase, which occurs between two columnar phases. The dielectric anisotropy is positive. The elastic constants are ∼10−7 dyne, which is of the same order as for nematics of rod-like molecules. Further, k33 > k11, probably as a consequence of the columnar short range order in the medium

Electrooptic soft mode response of compounds exhibiting the antiferroelectric phase

We report measurements on the electrooptic response of thin samples (~2-5 μm) of two antiferroelectric liquid crystals. All the phase transitions in these compounds can be very easily detected using this technique. We have been able to measure such an electrooptic effect for the first time in the antiferroelectric and smectic I∗ phases of a tolane compound. The response shows a relaxation at high frequencies (~10 KHz) and is at-tributed to a soft mode which produces an asymmetry in the molecular tilt in successive layers

Effet à long terme d'injections intracérébroventriculaires d'anticorps dopaminergiques sur l'hypersensibilité comportementale chez la souris

ln the present study the effect ofrepeated intracerebroventricular (ICV) of anti-conjugated dopamine antibodies (Acm anti-DAc) was investigated on behavioural supersensitivity and eating behavior. Mice were injected in ICV (with an ICV cannula) with either Acm anti-DAc or no immuns immunoglobulins (IgNI) twice a week for 5 weeks, their behavioural supersensitivity to apomorphine (0.05 mglkg) were measured. The results showed that Repeated intracerebroventricular injections of anti conjugated dopamine antibodies produced a behavioural supersensitivity to apomorphine. Immunohistochemical analysis showed that the behavioural supersensitivity is not due to DA celllosses in the substantia nigra or the ventral tegmentum area. Key words: Dopaminergic antibodies, Intracerebroventricular injections, Behavioural supersensitivity, Mice  Des injections intracérébroventriculaires répétées de l'anticorps monoclonal anti-dopamine conjuguée (ACm antiDAc) chez des souris Balb/c entraînent, pendant 8 semaines après la fin des injections, une hypersensibilité comportementale. L'analyse immunohistochimique montre que cette hypersensibilité ne semble pas liée directement à une perte des cellules DA dans la substance noire et dans l'aire tegmentale ventrale. Mots clés: Anticorps dopaminergiques, Injections intracérébroventriculaires, Hypersensibilité comportementale, Souri

A π-Extended Donor-Acceptor-Donor Triphenylene Twin linked via a Pyrazine-bridge

Beta-amino triphenylenes can be accessed via palladium catalyzed amination of the corresponding triflate using benzophe-none imine. Transformation of amine 6 to benzoyl amide 18 is also straightforward and its wide mesophase range demon-strates that the new linkage supports columnar liquid crystal formation. Amine 6 also undergoes clean aerobic oxidation to give a new twinned structure linked through an electron-poor pyrazine ring. The new discotic liquid crystal motif contains donor and acceptor fragments, and is more oval in shape rather than disk-like. It forms a wide range columnar mesophase. Absorption spectra are strong and broad; emission is also broad and occurs with a Stokes shift of ca. 0.7 eV, indicative of charge-transfer characte