Conductive liquid crystalline compounds having a piperazine structure

New conductive thermotropic liquid crystalline materials having a piperazine ring in the central core: 1-[4-(9-decenyloxy)phenyl]-4-alkylpiperazines ( 6 ) were synthesized. The mesomorphic behaviours of these compounds and their conductivity in the liquid crystal phase were measured. The principal features of these compounds are to exhibit a smectic B phase around room temperature (for example 6 : Cr 50 SmB 81 I, °C) and to exhibit a large dark current (6d: 430 μA cm^-2, applied voltage 20 V, at 70°C) in the smectic B phase.     

Composite wraps for aging infra-structure

The post war years, with Australia's rapid economic growth, was the period which began the construction of much of the current infra-structure. However, there are now doubts on its durability and structural integrity. Composite repairs and external composite reinforcement, may well be one method for addressing the problems of aging infra-structure. To this end the present paper evaluates the ability of externally bonded composite wraps to increase the load carrying capacity of concrete columns and beams. In this study the failure loads were found to occur when the composite wraps reached a critical strain level.     

Use of a birefringent filter for tuning a synchronously pumped optical parametric oscillator

Design considerations are presented for birefringent filters suitable for use as tuning elements in synchronously pumped optical parametric oscillators. A particular design aspect that is important, since typical gains are rather high, is the adequate suppression of subsidiary transmission maxima, in order to maximize the tuning range. Results are presented on the performance of a picosecond synchronously pumped optical parametric oscillator based on periodically poled lithium niobate with an appropriately designed four-plate birefringent filter. PACS 42.65.Yj; 42.72.Ai     

High pT π0 production from αα and αp collisions at the CERN ISR

The invariant cross sections for π⁰ meson production in alpha—alpha and alpha—proton collisions at the ISR were meas- ured up to transverse momenta of $\text{7}\text{GeV}\text{c}$ and $\text{8}\text{GeV}\text{c}$, respectively. These measurements are compared with π⁰ production in pp collisions at the same values of $\text{s}\text{/}$nucleon, and the variation of the nuclear A-dependence with p_T is determined.     

High power,single frequency operation of a Q-switched TEM00 Mode NdYAG laser

An actively Q-switched NdYAG laser, using a telescopic resonator configuration has produced single longitudinal mode, TEM₀₀ outputs of 100 mJ with output pulses free from any observable mode-beating.     

In-beam implantation of iron into germanium in an external magnetic field studied by the Mössbauer effect

In order to determine whether the doublet observed in the Mössbauer spectra of⁵⁷Fe after in-beam, recoil implantation into Ge is due to a quadrupole interaction or corresponds to two implantation sites, this implantation experiment was performed in the presence of a 35 kG external magnetic field. The resulting Mössbauer spectrum favors a dominant quadrupole interaction hypothesis.     

Performance of a Nd: YAG oscillator/ampflifier with phase-conjugation via stimulated Brillouin scattering

Phase conjugation via stimulated Brillouin scattering in CH₄ gas has been used to correct amplifier aberrations in a Nd: YAG oscillator/amplifier system. The single amplifier stage has been used in two-pass and four-pass arrangements. Using the four-pass arrangement incorporating compensation for thermal birefringence, a single-frequency diffraction-limited output of 350 mJ, in a compressed 6 ns pulse is achieved at 15 Hz repetition rate.