Highly aminated mesoporous silica nanoparticles with cubic pore structure

Mesoporous silica with cubic symmetry has attracted interest from researchers for some time. Here, we present the room temperature synthesis of mesoporous silica nanoparticles possessing cubic Pm3?n symmetry with very high molar ratios (>50%) of 3-aminopropyl triethoxysilane. The synthesis is robust allowing, for example, co-condensation of organic dyes without loss of structure. By means of pore expander molecules, the pore size can be enlarged from 2.7 to 5 nm, while particle size decreases. Adding pore expander and co-condensing fluorescent dyes in the same synthesis reduces average particle size further down to 100 nm. After PEGylation, such fluorescent aminated mesoporous silica nanoparticles are spontaneously taken up by cells as demonstrated by fluorescence microscopy.     

A model of the properties of colloidal dispersions of weakly interacting fine ferromagnetic particles

A Monte Carlo technique has been used to simulate the magnetic properties of a colloidal dispersion of weakly interacting fine ferromagnetic particles. The initial susceptibility is shown to obey a Curie-Weiss like law in its variation with temperature. The ordering temperature in the Curie-Weiss law is found to increase with the diameter of the particles, the increase being associated with an increase in the local order in the system. Data from the Monte Carlo simulation is also used to assess the effects of interactions on the determination of particle size parameters from magnetic measurements. Investigation of the spatial correlation within the system reveals evidence of field induced particle agglomeration.     

Die chemische Zusammensetzung von Wolle. IX. Abtrennung und Analyse von Makrofibrillen

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Comparison of methods of calculation of 13C-NMR chemical shifts of diene polymers with applications to isomerized natural rubber

Natural rubber was isomerized by two methods that involved either dehydrobromination of hydrobrominated natural rubber or heating natural rubber with butadiene sulfone. The ¹³C-NMR spectra of the methylene region of isomerized natural rubber was interpreted in terms of dyad arrangements for which assignments were made by calculating chemical shifts according to three different published methods. One method [Gronski, Murayama, Cantow, and Miyamoto, Polymer, 17 , 358 (1976)] gave the best overall agreement with the experimental chemical shifts; another [Sato, Ono, and Tanaka, Polymer, 18 , 580 (1977)] was better for C-1 and C-3 methylene carbon atoms; and still another [Khatchaturov, Dolinsky, Prozenko, Abramenko, and Kormer, Polymer 18 , 871 (1977)] gave results which deviated considerably from the other methods. From ¹³C-NMR intensity measurements it was shown that the elimination of HBr from hydrobrominated natural rubber occurred by a random process. Contrary to literature reports, it was found that the sulphur dioxide catalyzed isomerization of natural rubber was accompanied by a significant amount of double bond migration; a possible reaction scheme was proposed.     

Measurement of the Temperature Dependence of the ddμ-Molecule Formation Rate in Dense Deuterium at Temperatures 300–800 K

Muon catalyzed fusion in deuterium was studied by the MCF collaboration at JINR phasotron. The measurements were carried out with a high-pressure deuterium target at the JINR phasotron in the temperature range 300–800 K at densities ≃0.5 LHD. The first experimental results for ddμ-molecule formation rate λ _ddμ in the temperature range 400–800 K with deuterium density 0.5 LHD are presented. This revised version was published online in August 2006 with corrections to the Cover Date.     

Nonlinear prediction of crown–of–thorns outbreaks on the great barrier reef

The Zakai form of nonlinear prediction theory is used to estimate yearto-year state changes in crown-of-thorns starfish populations of the Great Barrier Reef. Taking the previously defined coral-state diffusion as observation process and the starfish-state diffusion as signal process, a least squares polynomial regression curve recently derived for simultaneously collected starfish/coral state data is used to set up the prediction preliminaries, Numerical results are not inconsistant with starfish outbreak values of the last 5 years and yield an expected high value for 1987. However, because of large error in the data it is doubtful that a more refined mesh for the Mihlstein approximations used to evaluate the Îto stochastic integrals involved in Zakai theory would improve the accuracy of predictions.     

Pseudo-steady-state solutions for solidification in a wedge

Polubarinova-Kochina's analytical differential equation methodis used to determine the pseudo-steady-state solution to problemsinvolving the freezing (solidification) of wedges of liquidwhich are initially at their fusion temperature. In particular,we consider four distinct problems for wedges which are: freezingwith the same constant boundary temperature, freezing with thesame constant boundary heat fluxes, freezing with distinct constantboundary temperatures and freezing with distinct constant fluxesat the boundaries. For the last two problems, a Heun's differentialequation with an unknown singularity is derived, which in bothcases admits a particularly elegant simple solution for thespecial case when the wedge angle is . The moving boundariesobtained are shown pictorially.     

Synthesis of analogs of prostacyclin containing a thiazone ring

Thiazole analogs of prostacyclin were prepared from the cyclopentene (9), itself, obtained $\text{via}$ novel opening of 3,4-epoxycyclopentene with the lithioallylthioether (4).     

Die chemische Zusammensetzung der Wolle XIII. Abtrennung und Analyse von Mikrofibrillen

Ohne Zusammenfassung