Copolymerisation von polaren Vinylmonomeren mit Butadien in Gegenwart von Lewis-S?uren

Ohne Zusammenfassung     

Etude de la Reactivite Entre L'orthophosphate Tricalcique Apatitique et L'oxalate de Calcium

Several difficulties arise when studying the mineral component of calcified tissues: This material is complex due to the large number of atomic components, its heterogeneous composition, and varying factors. It is linked strongly to the organic component, and today no available technique allows a complete separation of these two components without alteration of one of them. In the present work the interaction of apatitic calcium phosphate with calcium oxalate has been studied. By heating stoechiometric amounts of these two solids, it was found that the presence of CO 3 2 m and CaO produced by calcium oxalate induces a decrease in P 2 O 7 4 m arising from HPO 4 2 m content of apatitic calcium phosphate. L'étude physico-chimique de la partie minérale des tissus calcifiés est extrêmement étendue et complexe. Fortement liée à des composés organiques, des difficultés de séparation, d'identification et d'étude du comportement de ces matériaux ont été signalées par de nombreux auteurs. En vue d'identifier l'effet des ions carbonate CO 3 2 m et du CaO sur la détermination de la teneur des ions (HPO 4 2 m ) des apatites synthétiques, les interactions entre le phosphate tricalcique apatitique et l'oxalate de calcium ont été étudiées. Il a été constaté que les ions CO 3 2 m produits par le carbonate de calcium issu de l'oxalate de calcium, conduisent à une diminution relative de la teneur des ions P 2 O 7 4 m (provenant des ions HPO 4 2 m ) dans le mélange équimolaire de phosphate apatitique et d'oxalate de calcium, dans le domaine de températures 400-520°;C. Au-delà de 520°;C la seconde diminution de la teneur des ions P 2 O 7 4 m est attribuée aux interactions des ions P 2 O 7 4 m et du CaO.     

Two-component organogelators: combination of Nε-alkanoyl-L-lysine with various N-alkanoyl-L-amino acids: additional level of hierarchical control

Synthesis of two-component organogelation system was performed very easy and concise manner from N^ε-palmitoyl-L-lysine ethyl ester and N^ε-miristoyl-L-lysine ethyl ester in which they were used as base component and N-lauroyl-L-amino acids (amino acids:, alanine, leucine and phenylalanine as acid components.). And their organogelation properties were examined in different pharmaceutical fluids such as liquid paraffin, fatty acid ethyl, and isopropyl esters. In this way, gelation efficiency was ascertained variations of alkanoyl moieties and combination of different amino acids in the gelator structures. Characterization of gelators was performed via thermal measurement such as Tg and gel–sol enthalpy change; SEM and FTIR as optical methods.     

The effect of Benzo Substitution on Complexation of Diaza 18-crown-6 ethers Derivatives with NaClO4

The complexation of the crown ethers with Na⁺ ion was studied. ¹H-NMR chemical shifts are discussed in terms of structural modification as well as also binding studies with UV–vis spectra were included. This revised version was published online in July 2005 with a corrected issue number. An erratum to this article is available at .     

Enhanced ferroelectric polarization by induced Dy spin order in multiferroic DyMnO3

Neutron powder diffraction and single crystal x-ray resonant magnetic scattering measurements suggest that Dy plays an active role in enhancing the ferroelectric polarization in multiferroic DyMnO3 above T(Dy)(N)=6.5 K. We observe the evolution of an incommensurate ordering of Dy moments with the same periodicity as the Mn spiral ordering. It closely tracks the evolution of the ferroelectric polarization. Below T(Dy)(N), where Dy spins order commensurately, the polarization decreases to values similar for those of TbMnO3. The higher P(s) found just above T(Dy)(N) arises from the contribution of Dy spins so as to effectively increase the amplitude of the Mn spin spiral.     

Coupling of frustrated ising spins to the magnetic cycloid in multiferroic TbMnO(3)

We report on diffraction measurements on multiferroic TbMnO(3) which demonstrate that the Tb- and Mn-magnetic orders are coupled below the ferroelectric transition T(FE) = 28 K. For T相似文献   

Facile,single-pot preparation of nanoporous SiO2 particles (carrier) with AgNPs at core and crust for controlled disinfectant release

This study demonstrates a novel, facile and one-pot approach to synthesize silica nanoparticles with silver at core and crust (SiNP-AgCC). A modified Stöber method was used to make SiNP-AgCC. A significant reduction in the size of SiO₂ nanoparticles was seen, with 2–5 nm AgNPs being uniformly distributed on the surface and 10–20 nm AgNPs in the center. A typical mesoporous SiO₂ particle (SiNP) produced using the Stöber method was transformed to nanoporous SiO₂ by this modified Stöber method. Nanoporous SiO₂ particles with silver in the center are advantageous for slow and consistent Ag⁺ release, which was confirmed by Ag⁺ ion release test. Antibacterial activities of the samples were tested to evaluate the disinfection performance of the samples on gram-negative bacteria (Escherichia coli) using disk diffusion and the LB-agar method. SiNP-AgCC showed prolonged silver release for more than 20 days and improved antibacterial properties even after five days of incubation.     

Sol-gel thin films with anti-reflective and self-cleaning properties

Self-cleaning photocatalytic TiO₂ films are beneficial since they reduce the maintenance cost and enhance the efficiency of various optical systems, especially thermal and photovoltaic solar systems. However, the presence of a TiO₂ layer on glass reduces the transmission of incident light, which leads to a decrease in efficiency. This drawback can be overcome by applying a layer of anti-reflective coating beneath the TiO₂ layer. Generally, the anti-reflective layer is porous silica. The presence of the anti-reflective layer compensates for the loss of light transmittance caused by the photocatalytic TiO₂ top layer. This paper reviews some of the previous and the latest fundamental studies in the literature on anti-reflective, self-cleaning and multi-functional films.     

Magnetic structure of CuCrO?: a single crystal neutron diffraction study

This paper presents results of a recent study of multiferroic CuCrO(2) by means of single crystal neutron diffraction. This system has two close magnetic phase transitions at T(N) = 24.2 K and T(mf) = 23.6 K. The low temperature magnetic structure below T(mf) is unambiguously determined to be a fully three-dimensional proper screw. Between T(N) and T(mf) antiferromagnetic order is found that is essentially two-dimensional. In this narrow temperature range, magnetic near neighbor correlations are still long range in the (H,K) plane, whereas nearest neighbors along the L direction are uncorrelated. Thus, the multiferroic state is realized only in the low temperature three-dimensional state and not in the two-dimensional state.     

Novel polydentate phosphonic acids: Protonation and stability constants of complexes with Fe(III) and Cu(II) in aqueous medium

The acido‐basic and the complexation properties of di‐, tri‐, and tetra‐phosphonic acids (H₆L1, H₈L2, and H₁₀L3) toward Fe(III) and Cu(II) were determined by potentiometric titration in aqueous media at 25.0 ± 0.1°C with constant ionic strength (0.1 M, NaClO₄). We have determined six, ten, and eight pK_a values for the di, tri, and tetra‐phosphonic acids, respectively. In acidic conditions, e.g., 0 ≤ pH ≤ 5; iron and copper presented a high affinity toward these ligands to give complex species. With the ligand H₁₀L3, [FeL3H₇], and [CuL3H₆]²⁻ were easily obtained at pH 1.8 and 2.7, respectively. We have determined ten stability constants for the H₁₀L3/Fe system and nine for the H₁₀L3/Cu one; six and four in the cases of H₈L2/Fe and H₈L2/Cu systems, respectively. Finally, five stability constants were calculated for the H₆L1/Fe system and four for the H₆L1/Cu one. We have not observed any insoluble species in these complexes in acidic medium as well as in alkaline solutions. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:51–62, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20575