Douglas-FIR Bark. III. Sterol and Wax Esters of The n-Hexane WAX

Sterol and wax esters were isolated as chemically intact compounds from the n-hexane-soluble fraction of Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] bark in a continuing effort to elucidate the properties of this wax. The sterol esters were composed of sitosterol and campesterol esterified to any or all of the fatty acids, n-tridecanoic acid, n-hexadecanoic acid, n-heptadecanoic acid, cis-9-octadecenoic acid, n-nonadecanoic acid, n-eicosanoic acid, n-docosanoic acid, and n-tetracosanoic acid. The wax esters were composed of 1-docosanol and 1-tetracosanol, also esterified to the above-named acids. The fact that any or all of the fatty acids can be esterified to each of the sterols and alcohols, producing a great mixture of different sterol and wax esters, may partly account for the softness and low melting point of Douglas-fir n-hexane wax

Origin of the large phonon band-gap in SrTiO3 and the vibrational signatures of ferroelectricity in ATiO3 perovskite: First principles lattice dynamics and inelastic neutron scattering of PbTiO3, BaTiO3 and SrTiO3

We report first principles density functional perturbation theory calculations and inelastic neutron scattering measurements of the phonon density of states, dispersion relations and electromechanical response of PbTiO3, BaTiO3 and SrTiO3. The phonon density-of-states of the quantum paraelectric SrTiO3 is found to be fundamentally distinct from that of ferroelectric PbTiO3 and BaTiO3 with a large 70-90 meV phonon band-gap. The phonon dispersion and electromechanical response of PbTiO3 reveal giant anisotropies. The interplay of covalent bonding and ferroelectricity, strongly modulates the electromechanical response and give rise to spectacular signatures in the phonon spectra. The computed charge densities have been used to study the bonding in these perovskites. Distinct bonding characteristics in the ferroelectric and paraelectric phases give rise to spectacular vibrational signatures. While a large phonon band-gap in ATiO3 perovskites seems a characteristic of quantum paraelectrics, anisotropy of the phonon spectra correlates well with ferroelectric strength. These correlations between the phonon spectra and ferroelectricity, can guide future efforts at custom designing still more effective piezoelectrics for applications. These results suggest that vibrational spectroscopy can help design novel materials.Comment: 11 pages, 4 color figures and 2 Table

Endobronchial ultrasound-guided transbronchial needle aspiration in lung cancer: the first experience in Hong Kong.

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Magnons in real materials from density-functional theory

We present an implementation of the adiabatic spin-wave dynamics of Niu and Kleinman. This technique allows to decouple the spin and charge excitations of a many-electron system using a generalization of the adiabatic approximation. The only input for the spin-wave equations of motion are the energies and Berry curvatures of many-electron states describing frozen spin spirals. The latter are computed using a newly developed technique based on constrained density-functional theory, within the local spin density approximation and the pseudo-potential plane-wave method. Calculations for iron show an excellent agreement with experiments.Comment: 1 LaTeX file and 1 postscript figur

Dialkylimidazolium chloroaluminates: Ab initio calculations, Raman and neutron scattering measurements

The Raman and neutron scattering spectra of 46 mol% AlCl[sub 3] -54 mol% 1-ethyl-3-methyl imidazolium chloride (EMIC) and 67 mol% AlCl[sub 3] - 33 mol% EMIC melts are presented. Ab initio molecular orbital calculations have been carried out on structures of chloroaluminate anion and EMI cation and the interaction between anion and cation

Dialkylimidazolium Chloroaluminates: Ab Initio Calculations, Raman and Neutron Scattering Measurements

The Raman and neutron scattering spectra of 46 mol% AlCl{sub 3} -54 mol% 1-ethyl-3-methyl imidazolium chloride (EMIC) and 67 mol% AlCl{sub 3} - 33 mol% EMIC melts are presented. Ab initio molecular orbital calculations have been carried out on structures of chloroaluminate anion and EMI cation and the interaction between anion and cation

Linear Response Calculations of Spin Fluctuations

A variational formulation of the time--dependent linear response based on the Sternheimer method is developed in order to make practical ab initio calculations of dynamical spin susceptibilities of solids. Using gradient density functional and a muffin-tin-orbital representation, the efficiency of the approach is demonstrated by applications to selected magnetic and strongly paramagnetic metals. The results are found to be consistent with experiment and are compared with previous theoretical calculations.Comment: 11 pages, RevTex; 3 Figures, postscript, high-resolution printing (~1200dpi) is desire

Electron-phonon coupling induced pseudogap and the superconducting transition in Ba0.67K0.33BiO3

We study the single particle density of states (DOS) across the superconducting transition (Tc = 31 K) in single-crystal Ba0.67K0.33BiO3 using ultrahigh resolution angle-integrated photoemission spectroscopy. The superconducting gap opens with a pile-up in the DOS, Delta(5.3 K) = 5.2 meV and 2Delta(0)/kBTc = 3.9. In addition, we observe a pseudogap below and above Tc, occurring as a suppression in intensity over an energy scale up to the breathing mode phonon(~ 70 meV). The results indicate electron-phonon coupling induces a pseudogap in Ba0.67K0.33BiO3.Comment: 5 pages with 4 figures, submitted to Phys. Rev. Let

The potential and challenges of Ampang Jaya Municipal Council (MPAJ) towards achieving low carbon city (LCC): community perspectives

The goal of reducing carbon emissions by 30% by 2030 in Ampang Jaya requires participation from local authorities and the community itself. Thus, this study has been done to evaluate the potential Ampang Jaya Municipal Council (MPAJ) to achieve low carbon city (LCC). The Ampang Jaya area was selected as the area of observation because of its high population density and its high potential to achieve LCC. The study was conducted qualitatively using an in-depth semi-structured interview method and the data obtained were analysed using thematic analysis. Seven themes emerged from the in-depth interviews which can be incorporated into three dimensions namely themes execution and planning, enforcement of policies and, ongoing works by MPAJ under the dimension of readiness of local authorities; themes cleaner and healthier environment and, LCC in Ampang Jaya under the dimension of achievable milestones; and the themes of community’s daily lifestyle changes and roles by local authorities under the dimension of responsibilities. In principle, this research concludes that MPAJ has a high potential to achieve LCC while being able to overcome the challenges they face to achieve this feat