Search results for "Polar"

Theoretical study of 1,3-dipolar cycloaddition reactions with inverse electron demand - A DFT study of the lewis acid catalyst and solvent effects in…

2000

The molecular mechanism for the inverse electron demand 1,3-dipolar cycloaddition of nitrones with vinyl ethers has been characterized using density functional theory methods with the B3LYP functional and the 6−31G* basis set. Relative rates, regioselectivity, endo/exo stereoselectivity, Lewis acid catalyst and solvent effects are analyzed and discussed. Four reactive channels associated with the formation of two pairs of diasteromeric regioisomers have been characterized. Analysis of the geometries of the corresponding transition structures shows that the reaction in the gas phase takes place by an asynchronous concerted mechanism. These 1,3-dipolar cycloadditions present a large ortho reg…

ChemInform Abstract: Gas-Phase and Solution Basicities of Some Alkyl 2,6-Dialkylphenyl Ketones: A Comparative Analysis.

2000

Abstract The gas-phase basicity of a number of alkyl 2,6-dialkylphenyl ketones (2,6-R2C6H3COR′) has been found to be almost insensitive to structural variations, as a result of a compensation of steric and electronic effects associated with the bulkiness and to the polarizability, respectively, of R and/or R′. On the contrary, the basicity in concentrated sulfuric acid undergoes, along the same series of compounds, a variation of nearly 8 pK units, as a consequence of steric inhibition of solvation of the protonated carbonyl as the main effect played by R and/or R′. The results in the condensed phase agree very nicely with recent findings relevant to some 4-substituted 2,6-dimethylacetophen…

Flavour Separation of Helicity Distributions from Deep Inelastic Muon-Deuteron Scattering

2009

We present a LO evaluation of helicity densities of valence, \Delta u_v+\Delta d_v, non-strange sea, \Delta\bar{u}+\Delta\bar{d}, and strange quarks, \Delta s (assumed to be equal to \Delta\bar{s}). They have been obtained from the inclusive asymmetry A_{3,d} and the semi-inclusive asymmetries A^{\pi+}_{1,d}, A^{\pi-}_{1,d}, A^{K+}_{1,d}, A^{K-}_{1,d} measured in polarised deep inelastic muon-deuteron scattering. The full deuteron statistics of COMPASS (years 2002-2004 and 2006) has been used. The data cover the range Q^2 > 1 (GeV/c)^2 and 0.004<x<0.3. Both non-strange densities are found to be in a good agreement with previous measurements. The distribution of \Delta s(x) is compatible wit…

Real time optical immunosensing with flow-through porous alumina membranes

2014

Through the presentation of analytical data from bioassay experiments, measured by polarimetry, we demonstrate for the first time a real time immunoassay within a free standing macroporous alumina membrane. The 200 nm nominal pore diameter of the membrane enables flow-through, thereby providing an ideal fluidic platform for the targeted delivery of analytes to bioreceptors immobilized on the pore walls, enabling fast sensing response times and the use of small sample volumes (<100 mu L). For the immunoassay, the pore walls were first coated with the functional copolymer, copoly(DMA-NAS) using a novel coupling process, before immobilization of the allergen protein, beta-lactoglobulin, by spo…

Effects of illumination on the dielectric response of barium-strontium niobate ceramics

2013

A study of the effects of white light on the low and infra-low frequency relaxation of polarization in the barium-strontium niobate (SBN) ceramics is reported. The light is found considerably decreasing the contribution of space charge at temperatures corresponding to the range of the relaxor phase (it is, around the Tm).

Luigi Sturzo: un uomo, un sacerdote, un politico. Riflessioni sul libro di Eugenio Guccione, Luigi Sturzo.

2010

A premodern legacy: the "easy" criminalization of homosexual acts between women in the Finnish Penal Code of 1889.

1998

Homosexual acts between women were criminalized in Finland in the 1889 Penal Code which also criminalized men's homosexual acts for the first time explicitly in Finnish legislation. The inclusion of women in the Penal Code took place without much ado. In the article it is argued that the uncomplicated juxtaposing of men and women was due to the legacy of a cultural pattern where man and woman, as categories, were not in an all-pervasive polarity to each other, for example, in sexual subjectivity. A cultural pattern of low gender polarization was typical of preindustrial rural culture, and it can help us apprehend also certain other features in contemporary Finnish social and political life,…

Resolving the forbidden band of SF6

2013

Sulfur hexafluoride is an important molecule for modeling thermophysical and polarizability properties. It is also a potent greenhouse gas of anthropogenic origin, whose concentration in the atmosphere, although very low is increasing rapidly; its global warming power is mostly conferred by its strong infrared absorption in the ν3 S-F stretching region near 948 cm(-1). This heavy species, however, features many hot bands at room temperature (at which only 31% of the molecules lie in the ground vibrational state), especially those originating from the lowest, v6 = 1 vibrational state. Unfortunately, the ν6 band itself (near 347 cm(-1)), in the first approximation, is both infrared- and Raman…

A set-up for simultaneous measurement of second harmonic generation and streaming potential and some test applications.

2018

We present a measurement cell that allows simultaneous measurement of second harmonic generation (SHG) and streaming potential (SP) at mineral-water interfaces with flat specimen that are suitable for non-linear optical (NLO) studies. The set-up directly yields SHG data for the interface of interest and can also be used to obtain information concerning the influence of flow on NLO signals from that interface. The streaming potential is at present measured against a reference substrate (PTFE). The properties of this inert reference can be independently determined for the same conditions. With the new cell, for the first time the SHG signal and the SP for flat surfaces have been simultaneousl…

APPLICATION OF UNMANNED AERIAL VEHICLES FOR GLACIER RESEARCH IN THE ARCTIC AND ANTARCTIC

2019

Unmanned aerial vehicles or drones are nowadays widely used in a broad field of scientific and commercial applications. Despite this, it is quite a new method for glacier mapping in polar regions and has a lot of advantages, as well as disadvantages over more classical remote sensing instruments. Here we examine the main issues associated with the application of drones for glacier research from our experience in Iceland, Greenland and the Antarctic. We use DJI Phantom series drones for the obtaining of aerial photographs and produce digital surface models (resolution of 8 – 16 cm) and orthomosaics (resolution of 2 – 4 cm) for glacier mapping. Several issues related to the ground control poi…