Modele de »gaz oriente« applique a l\u27etude du spectre Raman externe du cristal d\u27anthracene

Une etude du spectre Raman de basses frequences est faite en utilisant !\u27excitation par un laser a gaz He-Ne. Une methode de mesure des intensites pour les spectres des cristaux est proposee. Les mesures d\u27intensite sont comparees avec les intensites calculees par le modele de gaz oriente

Modele de »gaz oriente« applique a l\u27etude du spectre Raman externe du cristal d\u27anthracene

Une etude du spectre Raman de basses frequences est faite en utilisant !\u27excitation par un laser a gaz He-Ne. Une methode de mesure des intensites pour les spectres des cristaux est proposee. Les mesures d\u27intensite sont comparees avec les intensites calculees par le modele de gaz oriente

Far Infrared and Raman Spectroscopic Investigations of the Lattice:Modes of Crystalline Thiophene

Vibrational spectroscopic measurements combined with the lattice statics and lattice mod es calculations have been applied in order to derive the most probable structure of the low temperature (stable) phase V of thiophene (below 112 K). The far infrared spectrum has been recorded from 135 to 30 cm? of this phase of thiophene at 20 K. The low frequency Raman spectrum from 150 to 10 cm" has also been record ed for the phase V at 35 K. From the fact that there is coincidence between lattice mode frequencies observed in the infrared and Raman spectra, one can exclude centrosymmetric space groups. The observations of 20 lattice modes in the Raman spectrum and 14 modes in the FIR spectrum eliminate the possibility of tetragonal symmetry, but the data are consistent with orthorhombic symmetry with the unit cell containing 4 molecules on Cl sites. In spite of the glassy-like transition observed for this phase at 42 K, both spectra bear striking resemblance to the typical low frequency spectra of molecular crystals. Therefore, it is assumed, for the purposes of the static and dynamic studies, that the thiophene in phase V can be considered as an ideally ordered crystal. Calculations of the lattice energy and lattice mode frequencies, based on the atom-atom potential, appear to be most consistent with space group Pca2l (C2v5) which is in agreement with most of the earlier predictions made for the structure of the thiophene phase V. The Raman spectrum of the metastable phase II2 is also given

Far Infrared and Raman Spectroscopic Investigations of the Lattice:Modes of Crystalline Thiophene

Vibrational spectroscopic measurements combined with the lattice statics and lattice mod es calculations have been applied in order to derive the most probable structure of the low temperature (stable) phase V of thiophene (below 112 K). The far infrared spectrum has been recorded from 135 to 30 cm? of this phase of thiophene at 20 K. The low frequency Raman spectrum from 150 to 10 cm" has also been record ed for the phase V at 35 K. From the fact that there is coincidence between lattice mode frequencies observed in the infrared and Raman spectra, one can exclude centrosymmetric space groups. The observations of 20 lattice modes in the Raman spectrum and 14 modes in the FIR spectrum eliminate the possibility of tetragonal symmetry, but the data are consistent with orthorhombic symmetry with the unit cell containing 4 molecules on Cl sites. In spite of the glassy-like transition observed for this phase at 42 K, both spectra bear striking resemblance to the typical low frequency spectra of molecular crystals. Therefore, it is assumed, for the purposes of the static and dynamic studies, that the thiophene in phase V can be considered as an ideally ordered crystal. Calculations of the lattice energy and lattice mode frequencies, based on the atom-atom potential, appear to be most consistent with space group Pca2l (C2v5) which is in agreement with most of the earlier predictions made for the structure of the thiophene phase V. The Raman spectrum of the metastable phase II2 is also given

Possible Superconducting State up to 210 K in the new Composition of Y-Ba-Cu-O

We have observed the zero resistance state up to 210 K in the mixed system of nominal composition Yj.2BaOSCu04-prepared under simultaneous action oi pulsed electric field up to 30 kV/cm and uniaxial force of 180 kN. The onset of the decrease of the resistance at 281 K in the repeated cycles and preliminary data diamagnetism are understood by us as a possible superconductivity event related to a particular composition

Pionska apsorpcija u 4He

This paper presents a large solid angle measurement of the positive pion absorption cross-section on 4He and its decomposition into partial channels. A large fraction of the absorption cross-section at incident pion kinetic energies of Tπ+ =70, 118, 162, 239, and 330 MeV is due to multinucleon channels.Daju se ishodi mjerenja pod velikim prostornim kutom udarnog presjeka za apsorpciju pozitivnih piona u He4 i razdjela na pojedine kanale. Velik dio apsorpcijskog udarnog presjeka za energije upadnih piona od Tπ+ =70, 118, 162, 239 i 330 MeV je posljedica višenukleonskih kanala

Pionska apsorpcija u 4He

This paper presents a large solid angle measurement of the positive pion absorption cross-section on 4He and its decomposition into partial channels. A large fraction of the absorption cross-section at incident pion kinetic energies of Tπ+ =70, 118, 162, 239, and 330 MeV is due to multinucleon channels.Daju se ishodi mjerenja pod velikim prostornim kutom udarnog presjeka za apsorpciju pozitivnih piona u He4 i razdjela na pojedine kanale. Velik dio apsorpcijskog udarnog presjeka za energije upadnih piona od Tπ+ =70, 118, 162, 239 i 330 MeV je posljedica višenukleonskih kanala

Transverse-spin dependence of the p-p total cross section ΔσT from 0.8 to 2.5 GeV/c

The difference ΔσT=σ(↓↑)-σ(↑↑) between the proton-proton total cross sections for protons in pure transverse-spin states, was measured at incident momenta 0.8 to 2.5 GeV/c in experiments performed at the Los Alamos Clinton P. Anderson Meson Physics Facility and the Argonne Zero Gradient Synchrotron. In agreement with other data, peaks were observed at center-of-mass energies of 2.14 and 2.43 GeV/c2, where 1D2 and 1G4 dibaryon resonances have been proposed

Measurement of the imaginary part of the I=1 N-barN S-wave scattering length

The survival time spectrum of slow antineutrons produced in a liquid-hydrogen target has been measured. From these data the imaginary part of the I=1 spin-averaged S-wave antineutron proton scattering length has been deduced to be Ima1=-0.83±0.07 fm. The result lies within the range of values calculated from current potential models. In addition, by combining a1 with the antiproton-proton scattering length deduced from antiprotonic atoms, the imaginary part of the I=0 spin-averaged N¯N scattering length was calculated to be Ima0=-1.07±0.16 fm

Toxicological Effects of Weapons of Mass Destruction and Noxious Agents in Modern Warfare and Terorrism

Oružja za masovno uništavanje najbolji su primjer uporabe civilizacijskih tehnoloških dostignuća u štetne svrhe i protiv ljudske civilizacije. Unatoč nastojanjima oko kontrole i smanjenja njihove količine, rizik zbog samoga postojanja pa čak i širenja zahtijeva da se o njihovoj uporabi i dalje vodi računa i da se povećaju obrambene mjere – nuklearno-biološko-kemijske obrane (NBKO). Osim suvremenog vojnika koji je u vojnim i mirovnim operacijama diljem svijeta izložen raznim noksama kemijskog, biološkog i radiološkog podrijetla, nezaštićeno i uglavnom slabo educirano civilno stanovništvo može biti izloženo terorističkim napadima. Oružja za masovno uništavanje i nokse kemijskog, biološkog i radiološkog podrijetla uzrokuju razne toksikološke posljedice, a bez obzira na njihovo podrijetlo, imaju zajednički nazivnik djelovanja – poremećaj fi ziološkog stanja u organizmu. Poremećaji proizašli nakon izlaganja tim noksama nerijetko se teško determiniraju, dijagnosticiraju i liječe. U ovome su radu s biomedicinskog aspekta obrađene važnije nokse kemijskog, biološkog i radiološkog podrijetla na temelju odabranih primjera iz terorizma i suvremenog ratovanja: polonij-210, osiromašeni uran, salmonela, bedrenica (antraks), genetički modifi cirane bakterije, polimerno predivo “paučina” i bojni otrovi sarin i iperit.Weapons of mass destruction (WMD) best portray the twisted use of technological achievements against the human species. Despite arm control efforts, WMD threat continues to exist and even proliferate. This in turn calls for improvement in defensive measures against this threat. The modern soldier is exposed to a number of chemical, biological, and radiological agents in military and peace operations, while civilians are mainly exposed to terrorist attacks. Regardless of origin or mode of action, WMDs and other noxious agents aim for the same – to make an organism dysfunctional. Because their effects are often delayed, these agents are hard to spot on time and treat. This review presents a biomedical aspect of agents used in warfare and terrorism, including polonium-210, depleted uranium, salmonella, anthrax, genetically modifi ed bacteria, cobweb-like polymer fi bre, sarin, and mustard gas