X-ray diffraction and structure of water

With the help of X-ray diffraction, liquid water at 25°C has been studied. The results agree fairly well with previous work, including the work of van Panthaleon van Eck, Mendel & Boog (1957-1962). The radial distribution function obtained is in accordance with an irregular network model, resembling ice I and the high pressure modifications, ice II, ice III, ice V and ice VI. Unlike the situation in the ice structures, in water a fraction of the hydrogen bonds are broken and all hydrogen bonds have approximately the same chance of being broken. Accordingly, each molecule is not surrounded by 4 hydrogen-bonded neighbours but by a somewhat smaller number, probably 3.2 (on average); moreover, there appear to be 4.6 non-bonded neighbours at a distance of less than 4 Å from the reference molecule

Magnetic catalyst bodies

After a discussion about the importance of the size of the catalyst bodies with reactions in the liquid-phase with a suspended catalyst, the possibilities of magnetic separation are dealt with. Deficiencies of the usual ferromagnetic particles are the reactivity and the clustering of the particles. A procedure to produce more suitable magnetic particles is to deposit a nickel± iron precursor on a support and to obtain small metal particles by reduction. Subsequently the metal particles are encapsulated in layers of graphitic carbon by exposure to methane at 700°C. Exposure to methane at lower temperature leads to growth of carbon fibrils, which can be controlled by raising the temperature. The alumina support is dissolved in hydrochloric acid. The magnetic properties of nickel-iron alloys prevent clustering of the ferromagnetic particles

An algorithm for calculating the Lorentz angle in silicon detectors

Future experiments will use silicon sensors in the harsh radiation environment of the LHC (Large Hadron Collider) and high magnetic fields. The drift direction of the charge carriers is affected by the Lorentz force due to the high magnetic field. Also the resulting radiation damage changes the properties of the drift. In this paper measurements of the Lorentz angle of electrons and holes before and after irradiation are reviewed and compared with a simple algorithm to compute the Lorentz angle.Comment: 13 pages, 7 figures, final version accepted by NIMA. Mainly clarifications included and slightly shortene

Процес «Спілки Визволення України» та зростання селянського опору в умовах суцільної колективізації

Мета даної роботи полягає у з’ясуванні механізму використання матеріалів процесу «СВУ» на території сучасної Чернігівщини, пропагандистських цілях та реакції на нього з боку як населення, лояльного до влади, так і селян, які вперто чинили опір політиці колективізації

Diamond thin Film Detectors for Beam Monitoring Devices

Diamonds offer radiation hard sensors, which can be used directly in primary beams. Here we report on the use of a polycrystalline CVD diamond strip sensor as beam monitor of heavy ion beams with up to 2.10^9 lead ions per bunch. The strips allow for a determination of the transverse beam profile to a fraction of the pitch of the strips, while the timing information yields the longitudinal bunch length with a resolution of the order of a few mm.Comment: 6 pages, 7 figures, to appear in the Proceedings of the Hasselt Diamond Workshop (Hasselt, Belgium, Feb. 2006), v4: accidentally submitted figure, appearing at end, remove

Monitoring communication development between teachers and their students with congenital deafblindness:An application of the Layered Communication Model

The Layered Communication Model (LCM) consists of three layers of intersubjective development divided into different communicative behaviors per layer. Earlier research showed that the LCM can be used to describe the communication level between teachers and their students with congenital deafblindness (CDB). This study analyzed whether the LCM can also be used to monitor the development of LCM behaviors over time. Videos of eight student-teacher dyads recorded at the start of this study (baseline phase) and 5 months later (follow-up phase) were coded using 10-s partial interval coding. The presence of the communicative behaviors at the three layers of the LCM during baseline and follow-up were calculated and compared between dyads and phases. The results on the presence of LCM behaviors were in line with earlier research. The presence of primary layer behaviors was comparable between dyads, confirming that this is a basic communication layer. The differences found between dyads in the presence of secondary and tertiary layer behaviors shows that these can be used to determine a dyad's communicative level. Results also showed that the LCM can be used to monitor communication development. Small increases were found in the presence of LCM behaviors between baseline and follow-up for the primary layer behaviors, but larger increases were found for secondary and tertiary layer behaviors, showing that development can be monitored. In conclusion, this study again showed that the LCM can be used to describe a dyad's communicative level. We also found increases in the presence of certain behaviors between baseline and follow-up for all dyads, which shows that the LCM can also be used to monitor communication over time. More insight into the period between the analyzed phases is suggested to analyze what might have caused the increase in presence of behaviors. This would reveal more about the use of the LCM as a tool to improve communication development

The hydration of divalent cations in aqueous solution : an x-ray investigation with isomorphous replacement

The x-ray diffraction patterns of M solns. of the nitrates of Co2+, Ni2 +, Zn2+, Mg2+, Cd2+, and Ca2+ were recorded with an Enraf-Nonius liq . jet diffraction camera. These cations were paired into 4 isomorphous groups based on the similarities of the cation-water distances in their cryst. hydrates. A theoretical expression was derived relating the electron distribution function to the difference in the intensities diffracted by a pair of isomorphous solns., and this function was obtained by calcg. the Fourier transform, using the measured intensities. The resulting electron distribution function exhibited a peak near 2 g, ascribed to the primary hydration layer, and a 2nd, less clear-cut, peak near 4 .ANG., attributed to the secondary hydration layer. Least-squares fits of these peaks yielded primary coordination nos. and cation water distances at 25°, and a secondary coordination no. of 12 ± 2. Cation-water distances were also obtained when minor deviations from isomorphism were taken into account

On Rank Problems for Planar Webs and Projective Structures

We present old and recent results on rank problems and linearizability of geodesic planar webs.Comment: 31 pages; LaTeX; corrected the abstract and Introduction; added reference