A Nematic to Nematic Transformation Exhibited by a Rod-Like Liquid Crystal

A novel, highly polar rod-like liquid crystal was found to exhibit two distinct nematic mesophases (N and Nx). When studied by microscopy and X-ray scattering experiments, and under applied electric fields, the nematic phases are practically identical. However, calorimetry experiments refute the possibility of an intervening smectic mesophase, and the transformation between the nematic phases was associated with a weak thermal event. Analysis of measured dielectric data, along with molecular properties obtained from DFT calculations, applying the Maier-Meier relationship allowed for the degree of antiparallel pairing of dipoles in both nematic phases to be quantified. Based on the results, we conclude that the onset of the lower temperature phase is driven by the formation of antiparallel molecular associations

Evaluation of 4-alkoxy-40-nitrobiphenyl liquid crystals for use in next generation scattering LCDs

We have prepared nine members of the 4-alkoxy-40-nitrobiphenyl family of liquid crystals and evaluated their thermal behaviour by a combination of polarised optical microscopy, differential scanning calorimetry and small angle X-ray scattering, as well as in single pixel scattering devices for use in backlight free liquid crystal displays (LCDs). Whereas homologues with shorter terminal aliphatic chains are nematogenic, those with longer aliphatic chain lengths exhibit an additional smectic A phase, identified as the subtype SmAD by SAXS with all materials having a D/L ratio (smectic layer spacing divided by molecular length) of 1.4. When doped with 0.1 wt% hexadecyltrimethylammonium perchlorate we observed that the SmAD phase of compound 9 could be switched with a relatively low voltage (58 VRMS, roughly half that required for the analogous nitrile). This apparent reduction in threshold voltage, which occurs as a consequence of switching from a nitrile- to a nitro- group, provides a new impetus to study alternative polar terminal groups when designing host materials for smectic A scattering devices

A Survey of Monte Carlo Tree Search Methods

Monte Carlo tree search (MCTS) is a recently proposed search method that combines the precision of tree search with the generality of random sampling. It has received considerable interest due to its spectacular success in the difficult problem of computer Go, but has also proved beneficial in a range of other domains. This paper is a survey of the literature to date, intended to provide a snapshot of the state of the art after the first five years of MCTS research. We outline the core algorithm's derivation, impart some structure on the many variations and enhancements that have been proposed, and summarize the results from the key game and nongame domains to which MCTS methods have been applied. A number of open research questions indicate that the field is ripe for future work

Experimental and molecular dynamics studies of anthraquinone dyes in a nematic liquid-crystal host: a rationale for observed alignment trends

Five anthraquinone dyes with bis(4-propylphenyl) substituents, connected via sulfide or amine linking groups at the 1,5-positions or directly at the 2,6-positions, have been studied as guests in the nematic liquid crystal host, E7. Polarized UV-visible absorption spectra of aligned samples were used to obtain experimental dichroic order parameters, which exhibit values in the range 0.51-0.74. Fully atomistic MD simulations of these guest-host systems were carried out, generally using default parameters but using new force constants derived here for the dyes containing flexible phenyl-sulfide and phenyl-amine linking groups. An analysis of the alignment of the dye molecules in these simulations provides calculated molecular order parameters, which are combined with calculated order parameters for the alignment of the transition dipole moments within the dyes, reported previously, to give calculated dichroic order parameters. The trend in the calculated dichroic order parameters between the dyes shows a good match with the trend in the experimental values, enabling the observed variation to be rationalised primarily by changes in the alignment of the calculated transition dipole moments within the dyes; the calculated molecular order parameters show a relatively small variation between the dyes. The results indicate that this computational approach may be used generally to rationalise trends in the alignment of guest molecules in liquid crystal hosts, suggesting that it may also be able to provide a predictive aid in the design of guest dyes

Characterizing the role of haloperidol for analgesia in the Emergency Department

The purpose of this study was to characterize emergency department (ED) physicians' beliefs and current practices regarding the use of haloperidol for the management of acute and acute on chronic pain. METHODS: A survey regarding haloperidol use was distributed by email to attending physicians, resident physicians, nurse practitioners, and physician assistants at emergency medicine departments in the Indiana University Health System and at St Joseph Mercy Ann Arbor. RESULTS: Of the 129 responses received, the majority (89.1%) of providers had used haloperidol for control of pain in the ED. The most common reason that respondents used haloperidol to treat pain was that they did not want to use an opioid or other agent (91.3%). The majority of providers (73.9%) believed that haloperidol was effective because there is a psychiatric component to pain, while over half of respondents (58.3%) chose haloperidol as they believed it to have analgesic properties. When haloperidol was used as a first line medication, providers felt that it was effective in controlling pain about 69.0% of the time without the need for further medication. The most common presentations for use were for unspecified abdominal pain, headache, and gastroparesis. CONCLUSION: ED providers reported using haloperidol most often as a second line treatment to manage both acute and acute on chronic pain. When haloperidol was used as a first line agent, providers claimed that additional medicines were not usually required. Haloperidol may provide an effective alternative to opioids in treatment of acute pain and acute exacerbations of chronic pain in the ED

Magnetic and Dyed Microcapsules From the Spores of Clubmoss

In this article we describe the preparation of bioavailable microcapsules derived from spores of clubmoss (Lycopodium clavatum) that are composed of protein-free, non-allergenic, and porous sporopollenin, often described as nature’s most robust polymeric system. We describe the adsorption of magnetic materials onto the exterior surfaces of the empty microcapsules and the incorporation of molecular passengers, thereby producing stable, monodispersed, bifunctional particles/vehicles of 25 microns in size that can respond to, or targeted by, applied fields

Relationship between community drug administration strategy and changes in trachoma prevalence, 2007 to 2013

Australia is the only high income country with persisting endemic trachoma and a national control program has been in place since 2006. The program involves annual screening of children for trachoma in communities designated to be at high risk of disease and treatment of those affected with the antibiotic azithromycin. Depending on the level of trachoma detected in children, antibiotic treatment is also given to households and other community members. We used data collected annually from 2007 to 2013 to examine what effect the extent of azithromycin treatment had on subsequent levels of trachoma in children aged 5–9 years. We found that in communities with high levels of trachoma, when all community members received azithromycin (community-wide treatment), the greatest reduction in trachoma level was achieved. However in communities with moderate levels of trachoma, using either community-wide treatment or more targeted (household) treatment resulted in equivalent reductions in trachoma. This observation needs to be confirmed in other studies before changes to current recommendations regarding trachoma control strategies are considered

A three-dimensional numerical method for modelling weakly ionized plasmas

Astrophysical fluids under the influence of magnetic fields are often subjected to single-fluid or two-fluid approximations. In the case of weakly ionized plasmas however, this can be inappropriate due to distinct responses from the multiple constituent species to both collisional and non-collisional forces. As a result, in dense molecular clouds and proto-stellar accretion discs for instance, the conductivity of the plasma may be highly anisotropic leading to phenomena such as Hall and ambipolar diffusion strongly influencing the dynamics. Diffusive processes are known to restrict the stability of conventional numerical schemes which are not implicit in nature. Furthermore, recent work establishes that a large Hall term can impose an additional severe stability limit on standard explicit schemes. Following a previous paper which presented the one-dimensional case, we describe a fully three-dimensional method which relaxes the normal restrictions on explicit schemes for multifluid processes. This is achieved by applying the little known Super TimeStepping technique to the symmetric (ambipolar) component of the evolution operator for the magnetic field in the local plasma rest-frame, and the new Hall Diffusion Scheme to the skew-symmetric (Hall) component.Comment: 13 pages, 9 figures, accepted for publication in MNRA