Small-angle neutron scattering

Small-angle neutron scattering is an experimental technique that uses elastic neutron scattering at small scattering angles to investigate the structure of various substances at a mesoscopic scale of about 1–100 nm. Small angle neutron scattering is in many respects similar to small-angle X-ray scattering. Advantages of SANS over SAXS are its sensitivity to light elements, the possibility of isotope labelling, the strong scattering by magnetic moments. During a SANS experiment a beam of neutrons is directed at a sample, which can be an aqueous solution, a solid, a powder, or a crystal; the neutrons are elastically scattered by nuclear interaction with the nuclei or interaction with magnetic momentum of unpaired electrons. In X-ray scattering, photons interact with the electronic cloud so the bigger the element, the bigger the effect is. In neutron scattering, neutrons interact with nuclei and the interaction depends on the isotope. In zero order dynamical theory of diffraction the refractive index is directly related to the scattering length density and is a measure of the strength of the interaction of a neutron wave with a given nucleus.

The following table shows the neutron scattering length for a few chemical elements. Note that the relative scale of the scattering lengths is the same. Another important point is. Hydrogen is one of the few elements that has a negative scatter, which means that neutrons deflected from hydrogen are 180° out of phase relative to those deflected by the other elements; these features are important for the technique of contrast variation. SANS uses collimation of the neutron beam to determine the scattering angle of a neutron, which results in an lower signal-to-noise ratio for data that contains information on the properties of a sample at long length scales, beyond ~1 μm; the traditional solution is to increase the brightness of the source, as in Ultra Small Angle Neutron Scattering. As an alternative Spin-echo Small-angle Neutron Scattering was introduced, using neutron spin echo to track the scattering angle, expanding the range of length scales which can be studied by neutron scattering to well beyond 10 μm.

Grazing-incidence small-angle scattering of neutron reflectometry. A crucial feature of SANS that makes it useful for the biological sciences is the special behavior of hydrogen compared to deuterium. In biological systems hydrogen can be exchanged with deuterium which has minimal effect on the sample but has dramatic effects on the scattering; the technique of contrast variation relies on the differential scatter of hydrogen vs. deuterium. Figure 1 shows the scattering length density for water and various biological macromolecules as a function of the deuterium concentration. Biological samples are dissolved in water, so their hydrogens are able to exchange with any deuteriums in the solvent. Since the overall scatter of a molecule depends on the scatter of all its components, this will depend on the ratio of hydrogen to deuterium in the molecule. At certain ratios of H2O to D2O, called match points, the scatter from the molecule will equal that of the solvent, thus be eliminated when the scatter from the buffer is subtracted from the data.

For instance the match point for proteins is around 40-45% D2O, at that concentration the scatter from the protein will be indistinguishable from that of the buffer. To use contrast variation, different components of a system must scatter differently; this can be based on inherent scattering differences, e.g. DNA vs. protein, or arise from differentially labeled components, e.g. having one protein in a complex deuterated while the rest are protonated. In terms of modelling, small-angle X-ray and neutron scattering data can be combined with the program MONSA. An example in which SAXS, SANS and EM data has been used to build an atomic model of a large multi-subunit enzyme has been published. For some examples of this method see. There are numerous SANS instruments available worldwide at Neutron Facilities such as research reactors or spallation sources. Neutron microscope Fejgin, Lev A.: Structure analysis by small-angle X-ray and neutron scattering. New York: Plenum. Higgins, Julia S.. Oxford: Clarendon Press.

The Small-Angle Scattering portal, link collection, with elaborate software list World directory of SANS instruments B. Hammouda: Probing Nanoscale Structures - The SANS Toolbox Small Angle Scattering at ISIS Neutron and Muon Source

Keeva Fennelly

Keeva Fennelly is a camogie player and financial reporter. She played in the 2009 All Ireland camogie final, she won an All-Ireland Junior medal in 2002 and a National League medal in 2008. She was the 2009 league-winning captain. Keeva's father Ger and uncles all gave distinguished service to Kilkenny, she has two first cousins, Leann Fennelly and Kelly Ann Cotterell, on the 2009 All Ireland panel, while another cousin, Michael Fennelly, captained the Kilkenny hurlers in 2009. Official Camogie Website Kilkenny Camogie Website of 2009 championship in On The Ball Official Camogie Magazine Fixtures and results] for the 2009 O'Duffy Cup All-Ireland Senior Camogie Championship: Roll of Honour Video highlights of 2009 championship Part One and part two Video Highlights of 2009 All Ireland Senior Final Report of All Ireland final in Irish Times Independent and Examiner

Liberalism in Slovenia

This article gives an overview of liberalism in Slovenia. It is limited to liberal parties with substantial support proved by having had a representation in parliament; the sign ⇒ means a reference to another party in that scheme. For inclusion in this scheme it isn't necessary so that parties labeled themselves as a liberal party. After the independence of Slovenia former young socialists claim to have restarted the liberal tradition of former Austria-Hungary, their organized liberalism became a major political force. The Liberal Democracy of Slovenia and profiles itself as a left of center liberal party. Others argue that there have been no liberal parties in Slovenia since independence in 1991, they say that claims of the former communist youth and LDS that they represent liberal parties with liberal doctrines are political propaganda and that facts demonstrate that both ZSMS and LDS followed socialist and anti liberal policies. 1894: Ivan Tavčar led the Young Slovenes to establish the National Party of Carniola.

In Gorizia related groups formed the National Progressive Party in 1900 1905: The Carniolan party is renamed National Progressive Party. In Upper Styria related groups formed the National Party of Styria 1918: The three party merged into the Yugoslav Democratic Party 1919: The party merged with Serbian and Croatian into the pan-Yugoslav more or less liberal State Party of Serbian and Slovene Democrats; some of the Slovene liberals did not join JDS and founded Independent Agrarian Party and National-Socialist Party. Except the name, the latter did not have much in common with German Nazis and could have been described as a social liberal party. 1919: The party is renamed into the Democratic Community 1920: The party is renamed into the Democratic Party. Leader is Ljubomir Davidović 1924: A faction, including the majority of prominent Slovene liberals formed the Independent Democratic Party active in Croatia, Bosnia and Slovenia 1929: After the royal coup, all parties were banned. 1931: Slovene liberals leaders joined the government party, from 1934 Yugoslav National Party.

*1935-1941: JNS was in opposition. 1941-1945: Following the Axis occupation of Yugoslavia, political parties were dissolved but continued activities in underground. Facing the communist insurgence, Slovene liberals co-founded the underground national organization Slovene Covenant. 1945: All democratic parties were dissolved and banned. 1989: The Socialist Youth League of Slovenia changes its name into Za Svobodo Mislecega Sveta and is shortly after reorganised into the Liberal Party 1990: The party is renamed into the Liberal Democratic Party 1994: The party merged with the ⇒ Democratic Party, a faction of the Slovenian Greens' and the Socialist Party of Slovenia into the Liberal Democracy of Slovenia, led by Janez Drnovšek 1989: Oppositionals established the Slovenian Democratic League 1991: The party is renamed Democratic Party, led by Dimitrij Rupel 1994: Most of the party merged into the ⇒ Liberal Democracy of Slovenia. A faction continued under the label Democratic Party of Slovenia Janez Drnovšek - Anton Rop Free Society Institute History of Slovenia Politics of Slovenia List of political parties in Slovenia