Temperature dependence of doping element incorporation with the chemical vapour deposition of epitaxial silicon (V). Incorporation of arsenic

Based on the knowledge previously obtained with regard to the incorporation of phosphorus as an equilibrium-determined process, theoretical values of the enthalpies of the different possible incorporation equilibria are calculated for the incorporation of arsenic into the growing silicon epitaxial layer. The sublimation enthalpies of elemental arsenic, the formation enthalpy of arsine and the enthalpy of solubility enter into the equation. The results compared to the present experimental data of other authors are discussed.     

Absorption and Distribution of Toltrazuril and Toltrazuril Sulfone in Plasma,Intestinal Tissues and Content of Piglets after Oral or Intramuscular Administration

Piglet coccidiosis due to Cystoisospora suis is a major cause of diarrhea and poor growth worldwide. It can effectively be controlled by application of toltrazuril (TZ), and oral formulations have been licensed for many years. Recently, the first parenteral formulation containing TZ in combination with iron (gleptoferron) was registered in the EU for the prevention of coccidiosis and iron deficiency anemia, conditions in suckling piglets requiring routine preventive measures. This study evaluated the absorption and distribution of TZ and its main metabolite, toltrazuril sulfone (TZ-SO₂), in blood and intestinal tissues after single oral (20 mg/kg) or single intramuscular (45 mg/piglet) application of TZ. Fifty-six piglets were randomly allocated to the two treatment groups. Animals were sacrificed 1-, 5-, 13-, and 24-days post-treatment and TZ and TZ-SO₂ levels were determined in blood, jejunal tissue, ileal tissue, and mixed jejunal and ileal content (IC) by high performance liquid chromatography (HPLC). Intramuscular application resulted in significantly higher and more sustained concentrations of both compounds in plasma, intestinal tissue, and IC. Higher concentrations after oral dosing were only observed one day after application of TZ in jejunum and IC. Toltrazuril was quickly metabolized to TZ-SO₂ with maximum concentrations on day 13 for both applications. Remarkably, TZ and TZ-SO₂ accumulated in the jejunum, the primary predilection site of C. suis, independently of the administration route, which is key to their antiparasitic effect.     

Struktur und Komplexbildung kleiner 1,3-dithiol-anellierter Thiakronenverbindungen

Structure and Complex Formation of Small 1,3-Dithiol Anellated Thia Crown Compounds The molecular structures of two 1,3-dithiol anellated nine membered thia crown compounds have been determined by X-ray diffraction. Their complex formation behaviour towards Ag^I and Hg^II is studied and discussed using solvent extraction experiments and molecular modeling calculations.     

Multicomponent latex IPN materials: 2. Damping and mechanical behavior

The integrals of the linear loss shear modulus vs. temperature (loss area, LA) and linear tan δ vs. temperature (tan δ area, TA) were characterized for various core/shell latex particles with synthetic rubber, poly(butadiene-stat-styrene) [P (Bd/S), 90/10], and interpenetrating polymer networks (IPN) as the cores. The IPN cores were composed of P(Bd/S) (T_g ≃ − 70°C) and an acrylate based copolymer (T_g around 10°C) for potential impact and damping improvement in thermoplastics. Poly(styrene-stat-acrylonitrile) (SAN, 72/28) was the shell polymer for all these polymers. Under the same loading, for both toughening and damping controls, among the IPN core/shell, blend of separate core/shell, and multilayered core/shell polymers, the IPN core/shell polymers were the best dampers. However, the other core/shell polymers also showed higher LA values than P(Bd/S)/SAN core/shell polymer. A comparison of LA values via a group contribution analysis method was made, the effect of particle morphology and phase continuity on damping being studied. Inverted core/shell latex particles (glassy polymer SAN was synthesized first) showed much higher LA and TA values than normal core/shell ones (rubbery polymer was synthesized first). Models for maximum LA and TA behavior are proposed. The damping property was essentially controlled by the phase miscibility and morphology of the core/shell latex particles. The LA values for each peak in these multiphase materials provided some indication of the several fractional phase volumes. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 1501–1514, 1997     

Simultaneous interpenetrating networks of a polyurethane and poly([methyl methacrylate]-stat-[N,N-dimethylacrylamide])

In a previous study, tetrahedron metastable phase diagrams were presented for a model simultaneous interpenetrating network (SIN) system of cross-polyurethane-inter-cross-poly(methyl methacrylate) (PU-PMMA). One triangular face of the overall tetrahedron diagram represented the ternary system MMA-PMMA-“U”, wherein “U” denotes the monomer/prepolymer mixture for the PU. In this article, a comonomer, N,N-dimethylacrylamide (DMA), is incorporated into the PMMA network. Thus, the above-mentioned ternary system is altered to “A”-PA-“U,” where “A” denotes the acrylic monomer mixture [MMA + DMA] and PA denotes the resulting copolymer. Glass transitions of fully cured samples were determined by dynamic mechanical spectroscopy (DMS). Phase separation was determined by the onset of turbidity, and gelation of the first gelling polymer was determined by the sudden resistance of the system to flow. The critical point, representing simultaneous phase separation and PA gelation, divides the overall composition for the reaction mixture (and the final SIN) into two parts. For one, gelation of the acrylic network precedes phase separation, and vice versa for the other part. In the absence of DMA in the PA network, the gelation-first region is very narrow, but with increasing amounts of copolymerized DMA, the critical point moves along the triangular face to increase the working area of the gelation-first region. © 1996 John Wiley & Sons, Inc.     

The current status of interpenetrating polymer networks

An interpenetrating polymer network, IPN, is defined as a combination of two or more polymers in network form, at least one of which is polymerized and/or crosslinked in the immediate presence of the other(s). The synthesis, morphology and mechanical properties of recent works are reviewed, with special emphasis on dual phase continuity, and the number of physical entanglements that arise in homo-IPNs. The concepts of phase diagrams are applied, especially to simultaneous interpenetrating network phase separations and gelations. Recent engineering applications are discussed.     

On-line Determination of Particle Size Distribution during the manufacture of compound feed

Experimental investigations were carried out with mainly a Mogensen-Sizer, compared with test screening and additionally laser diffraction and light extinction, in order to check the qualification for on-line determination of particle size distribution under the specific conditions of feed milling. The different components of compound feed, the degree of milling, the difference in measured particle characteristics and the possibility of sample dispersion affect the comparability of the results. The results show that laser diffraction is a manysided method with accurate recording of the distribution. The modified Mogensen-Sizer can be a robust low-price alternative if the control of selected distribution parameters is sufficient.     

Structural Principles for Anion‐Deficient,Fluorite‐Related Superstructures in the Zirconia‐Scandia System

The concept of the coordination defect (CD) was used recently by Bevan and Martin [6] to describe the fluorite‐related superstructures of the intermediate Pr/Tb oxides. The CD is an octahedron of corner‐shared OM_4/8 tetrahedra enclosing a □M_4/8 tetrahedron, where □ represents an oxygen vacancy. Various linkages of CDs can define a polyhedral prism with contents appropriate to the phase composition, and this is designated the “structural motif”. The identical, parallel top and bottom planes of this prism are the “motif plane”. This concept is now extended to explore the structures of the ordered phases, delta, gamma and beta, which occur in the zirconia‐scandia system, the respective formulae being Zr₃Sc₄O₁₂, Zr₁₀Sc₄O₂₆ and Zr₄₈Sc₁₄O₁₁₇ to Zr₅₀Sc₁₂O₁₁₈. It is shown that the motif plane is the same in each of the known structures (delta and gamma), thus defining the close relationship between them. Possible models for the as‐yet unknown structure of the beta phase, in which this same motif plane occurs, can then be proposed.