Mezopórusos hibrid anyagok új típusú előállítása = New preparation of mesoporous hybrid materials

Az alumínium-szilikát gélrendszerekkel végzett kísérletek célja a szol-gél módszerrel előállított gélminták törékenységének csökkentése volt az elért nagymértékű Al-beépülés megőrzése mellett. Polimerek adagolásával 4-5-szörös mechanikai szilárdságnövelést lehetett elérni, a hibridrendszerek vizes közegű mosása pedig 8-szorosra növelte a szilárdságot a fraktál szerkezetű alumínium-szilikát gélek szárított mintáihoz hasonlítva. A tenzidek alkalmazása az alumínium-szilikát géleknél szilárdság csökkenést okozott a fraktál szerkezet megbontása, széttöredezése miatt. Legnagyobb szilárdságnövelő hatást az alumínium-, ill. szilicium-prekurzorok szilárdság szempontjából optimális kiválasztásával értük el. A környezetvédelmi szempontoknak is jól megfelelő Al-acetát és az olcsó vízüveg adta egy új alumínium-szilikát előállítás alapanyagait. A vízüvegből és Al-acetátból nyert gélminta nagy szilárdsága egy nanokompozit szerkezetnek köszönhető, nanoméretű alumíniumtartalmú kristályos részecskék ágyazódnak be egy amorf alumínium-szilikát, háromdimenziós térhálóba. Ezt a kiváló mechanikai paramétert csak egy meghatározott Al/Si mólarány felett (? 2) lehetett elérni. A nagyobb szilárdságú anyagok jellemzésére szolgáló Vickers mérővel 100-300 HV értékek adódtak a megnövelt szilárdságú minták mérésekor, az összehasonlításul szolgáló fraktál szerkezetű, szárított alumínium-szilikát minták HV értéke 0 volt. | The aim of this work was to decrease the fragility of the gel samples prepared by sol-gel method and to retain the high Al incorporation into the silica network. The strength of the dried gel samples increases about four- or fivefold by the addition of polymers to the aluminosilicate component. A washing step improves the strength of these hybrid systems by seven- or eightfold. The tenside treatments gel samples decreased the mechanical strength, reduced the porosity by 30-80 % owing to the distortion of fractal structure. The largest increase of mechanical strength can be obtained by change of Al and Si precursors. Replacing the TEOS by cheap water glass solution (sodium metasilicate) and adding to the Al acetate aqueous solution, a hard, compact composite system developed in basic medium. Al-containing, crystalline nanoparticles are inserted in amorphous aluminosilicate network. The excellent hardness can be achieved only at or above 2 mole ratio of Al/Si. Vickers test detected the best values for mechanical property in the gel derived samples prepared from aluminum acetate and water glass solution (100-300 HV), the Vickers value of other gel derived aluminosilicate samples was 0

Carboxylic acid-functionalized porous silica particles by a co-condensation approach

Andrea Feinle, Franz Leichtfried, Sonja Straßer, Nicola Hüsin

Reversibly compressible and freestanding monolithic carbon spherogels

We present a versatile strategy to tailor the nanostructure of monolithic carbon aerogels. By use of an aqueous colloidal solution of polystyrene in the sol-gel processing of resorcinol-formaldehyde gels, we can prepare, after supercritical drying and successive carbonization, freestanding monolithic carbon aerogels, solely composed of interconnected and uniformly sized hollow spheres, which we name carbon spherogels. Each sphere is enclosed by a microporous carbon wall whose thickness can be adjusted by the polystyrene concentration, which affects the pore texture as well as the mechanical properties of the aerogel monolith. In this study, we used monodisperse polystyrene spheres of approximately 250 nm diameter, which result in an inner diameter of the final hollow carbon spheres of approximately 200 ± 5 nm due to shrinkage during the carbonization process. The excellent homogeneity of the samples, as well as uniform sphere geometries, are confirmed by small- and angle X-ray scattering. The presence of macropores between the hollow spheres creates a monolithic network with the benefit of being reversibly compressible up to 10% linear strain without destruction. Electrochemical tests demonstrate the applicability of ground and CO2 activated carbon spherogels as electrode materials

Advanced Materials Technologies / 3D Printing of Hierarchical Porous Silica and -Quartz

The ability to macroscopically shape highly porous oxide materials while concomitantly tailoring the porous network structure as desired by simple and environmentally friendly processes is of great importance in many fields. Here, a purely aqueous printing process toward deliberately shaped, hierarchically organized amorphous silica and the corresponding polycrystalline quartz analogues based on a direct ink writing process (DIW) is presented. The key to success is the careful development of the solgel ink, which is based on an acidic aqueous sol of a glycolated silane and structuredirecting agents. The resulting 3D (DIW) printed silica consists of a macroporous network of struts comprising hexagonally arranged mesopores on a 2D hexagonal lattice. Together with a printed porous superstructure on the millimeter scale, welldefined pore sizes and shapes on at least three hierarchy levels can thus be fabricated. The introduction of devitrifying agents in the printed green part and subsequent heat treatment allows for the transformation of the silica structure into polycrystalline quartz. While small pores (micro and mesopores below 10 nm) are lost, the printed morphology and the macroporous network of struts is preserved during crystallization.1605N20(VLID)266643

In situ SAXS study on cationic and non-ionic surfactant liquid crystals using synchrotron radiation

In situ synchrotron small-angle X-ray scattering was used to investigate various surfactant/water systems with hexagonal and lamellar structures regarding their structural behaviour upon heating and cooling. Measurements of the non-ionic surfactant Triton X-45 (polyethylene glycol 4-tert-octylphenyl ether) at different surfactant concentrations show an alignment of the lamellar liquid-crystalline structure close to the wall of the glass capillaries and also a decrease in d-spacing following subsequent heating/cooling cycles. Additionally, samples were subjected to a weak magnetic field (0.3-0.7 T) during heating and cooling, but no influence of the magnetic field was observed

Common germline polymorphisms associated with breast cancer-specific survival

Abstract Introduction Previous studies have identified common germline variants nominally associated with breast cancer survival. These associations have not been widely replicated in further studies. The purpose of this study was to evaluate the association of previously reported SNPs with breast cancer-specific survival using data from a pooled analysis of eight breast cancer survival genome-wide association studies (GWAS) from the Breast Cancer Association Consortium. Methods A literature review was conducted of all previously published associations between common germline variants and three survival outcomes: breast cancer-specific survival, overall survival and disease-free survival. All associations that reached the nominal significance level of P value <0.05 were included. Single nucleotide polymorphisms that had been previously reported as nominally associated with at least one survival outcome were evaluated in the pooled analysis of over 37,000 breast cancer cases for association with breast cancer-specific survival. Previous associations were evaluated using a one-sided test based on the reported direction of effect. Results Fifty-six variants from 45 previous publications were evaluated in the meta-analysis. Fifty-four of these were evaluated in the full set of 37,954 breast cancer cases with 2,900 events and the two additional variants were evaluated in a reduced sample size of 30,000 samples in order to ensure independence from the previously published studies. Five variants reached nominal significance (P <0.05) in the pooled GWAS data compared to 2.8 expected under the null hypothesis. Seven additional variants were associated (P <0.05) with ER-positive disease. Conclusions Although no variants reached genome-wide significance (P <5 x 10−8), these results suggest that there is some evidence of association between candidate common germline variants and breast cancer prognosis. Larger studies from multinational collaborations are necessary to increase the power to detect associations, between common variants and prognosis, at more stringent significance levels

Polysiloxane-based block copolymers as structure-directing agents in the synthesis of hierarchically organized silica monoliths

In this work the successful application of commercially available, linear PEO-PDMS-PEO block copolymers in the synthesis of hierarchically organized silica monoliths comprising a periodic arrangement of mesopores as well as a well-defined macroporous morphology is presented. All silica monoliths were synthesized via the sol-gel approach with an ethylene glycol-modified silane (EGMS) as precursor. Beyond their use as structure-directing agents, these siloxane surfactants can also be employed as agents to tailor the surface polarity by controlled thermal decomposition of the hydrophilic PEO blocks resulting in a hydrophobic organosiloxane-covered surface