Steric hindrance in the amine–epoxide reaction

The effect of steric hindrance on the reaction of silicon-containing aliphatic amines with phenylglycidyl ether (PGE) has been studied using ¹³C-NMR, a technique described by Sojka and Moniz [J. Appl. Polym. Sci., 20 , 1977 (1976)]. It was found that steric hindrance produced a large change in the reaction rate of the primary and secondary amine hydrogens, thus leading to a separation of the polymerization and cross-linking reactions.     

Banana‐shaped dopants for flexoelectric nematic mixtures

The synthesis is reported of new meta‐substituted quaterphenyls and several related dimers as dopants for nematic mixtures with flexoelectric properties. The number and nature of the terminal substituents is varied from apolar with a small dipole moment to polar with a strong dipole moment. The number of methylene units in the flexible aliphatic spacer between the polyfluorinated aromatic groups of the dimers is also varied. Dimers capable of banana‐shaped conformers induce an increase in the flexoelectric coefficients of mixtures containing them and reduce the clearing point to a small extent.     

Unsteady gravity-driven slender rivulets of a power-law fluid

Unsteady gravity-driven flow of a thin slender rivulet of a non-Newtonian power-law fluid on a plane inclined at an angle α to the horizontal is considered. Unsteady similarity solutions are obtained for both converging sessile rivulets (when 0 < α < π/2) in the case x < 0 with t < 0, and diverging pendent rivulets (when π/2 < α < π) in the case x > 0 with t > 0, where x denotes a coordinate measured down the plane and t denotes time. Numerical and asymptotic methods are used to show that for each value of the power-law index N there are two physically realisable solutions, with cross-sectional profiles that are ‘single-humped’ and ‘double-humped’, respectively. Each solution predicts that at any time t the rivulet widens or narrows according to |x | ^{(2N+1)/2(N+1)} and thickens or thins according to |x | ^N/(N+1) as it flows down the plane; moreover, at any station x, it widens or narrows according to |t | ^?N/2(N+1) and thickens or thins according to |t | ^?N/(N+1). The length of a truncated rivulet of fixed volume is found to behave according to |t | ^N/(2N+1).     

Facile asymmetric construction of a functionalized dodecahydrobenz[a]indolo[3,2-h]quinolizine template

We report a highly diastereoselective approach for the synthesis of a functionalized dodecahydrobenz[a]indolo[3,2-h]quinolizine ring system that is present as the heterocyclic core of the manadomanzamine alkaloids. We have achieved complete control over the relative and absolute stereochemistries at the three contiguous stereocentres at ring positions 1, 10 and 24 in only two linear synthetic steps. The introduction of useful functionality to the heterocyclic skeleton is significant as this may allow for future derivatization, and application of this route in an asymmetric synthesis of the manadomanzamine natural products.     

A Baseline Study of Metal Ion Content of Irish Canals by ICP-MS

The first systematic study of the metal ion content of the four main Irish Canal Systems is presented. Samples were collected seasonally over a twelve month period and analysed for 16 trace elements and metals by ICP-MS. The results show that three of the four canals (Royal, Grand, Shannon-Erne) have distinctly different elemental profiles, while the fourth (Barrow) is similar to the Grand Canal, which is to be expected, as they are broadly part of the same system, with a common main feeder. Spatial plots reveal local variations in certain elements, which are related to the nature of feeders in those localities. Simple tests based solely on the 16 elements measured showed that it may be possible to broadly define 'normal' compositions for each canal system, which can be then used to identify 'abnormal' data, and hence provide indicators for environmental change.     

Rod-shaped dopants for flexoelectric nematic mixtures

We report the synthesis and liquid crystalline behaviour of two series of para-substituted terphenyls as dopants with a rigid rod-like shape, rather than a wedge-, pear- or banana-shape, for guest–host nematic mixtures with flexoelectric properties. One series of liquid crystalline dopants is of low-to-strongly negative dielectric anisotropy and the other is of low-to-strongly positive dielectric anisotropy. The usefulness of apolar and polar rod-like dopants as components of flexoelectric nematic mixtures of positive dielectric anisotropy for use in LCDs is investigated in general and the dependence of the flexoelectric properties of the doped nematic mixtures on the polarity of the dopants is studied in particular. The correlation between the concentration of the dopant and the magnitude of the flexoelastic ratio of several guest–host nematic mixtures is investigated.     

Junctionless nanowire transistor fabricated with high mobility Ge channel

The junctionless nanowire metal–oxide–semiconductor field‐effect transistor (JNT) has recently been proposed as an alternative device for sub‐20‐nm nodes. The JNT architecture eliminates the need for forming PN junctions, resulting in simple processing and competitive electrical characteristics. In order to further boost the drive current, alternative channel materials such as III–V and Ge, have been proposed. In this Letter, JNTs with Ge channels have been fabricated by a CMOS‐compatible top–down process. The transistors exhibit the lowest subthreshold slope to date for JNT with Ge channels. The devices with a gate length of 3 μm exhibit a subthreshold slope (SS) of 216 mV/dec with an I_ON/I_OFF current ratio of 1.2 × 10³ at V_D = –1 V and drain‐induced‐barrier lowering (DIBL) of 87 mV. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)