Проблематика переходу до інформаційного суспільства

Аналізуються фундаментальні передумови, що є первинними в процесі творення інформаційного суспільства. Обґрунтовується теза, що електронна готовність та електронне залучення є основоположними факторами переходу суспільства від індустріального до інформаційного устрою. Подано основні характеристики цих понять та наголошено на їх значенні

Glycerol etherification over highly active CaO-based materials: new mechanistic aspects and related colloidal particle formation

Glycerol is an attractive renewable building block for the synthesis of di- and triglycerols, which have numerous applications in the cosmetic and pharmaceutical industries. In this work, the selective etherification of glycerol to di- and triglycerol was studied in the presence of alkaline earth metal oxides and the data are compared with those obtained with Na2CO3 as a homogeneous catalyst. It was found that glycerol conversion increased with increasing catalyst basicity; that is, the conversion increases in the order: MgO90 % at 60 % conversion) are obtained over CaO, SrO, and BaO. For these catalysts no substantial acrolein formation was observed. Furthermore, at the start of the reaction mainly linear diglycerol was produced, whereas at higher conversion degrees branched diglycerol started to form. In another series of experiments different types of CaO materials were prepared. It was found that these CaO-based materials not only differed in their surface area and number of basic sites, but also in their Lewis acid strength. Within this series the CaO material possessing the strongest Lewis acid sites had the highest catalytic activity, comparable to that of BaO, pointing towards the important role of Lewis acidity for this etherification reaction. Based on these observations a plausible alternative reaction scheme for glycerol etherification is presented, which considers the facilitation of the hydroxyl leaving process. Finally, the stability of the catalytic solids under study was investigated and it was found that colloidal CaO particles of about 50-100 nm can be spontaneously generated during reaction. Catalytic testing of these CaO colloids, after isolation from the reaction medium, revealed a very high etherification activity. Understanding the nature of these Ca-based colloids opens new opportunities for investigating supported colloidal particle catalysts to take advantage of both their hetero- and homogeneous nature

Electron Tomography Resolves a Novel Crystal Structure in a Binary Nanocrystal Superlattice

The self-assembly of different nanocrystals into a binary superlattice is of interest for both colloidal science and nanomaterials science. New properties may emerge from the interaction between the nanocrystal building blocks that are ordered in close contact in three dimensions. Identification of the superlattice structure including its defects is of key interest in understanding the electrical and optical properties of these systems. Transmission electron microscopy (TEM) has been very instrumental to reach this goal but fails for complex crystal structures and buried defects. Here, we use electron tomography to resolve the three-dimensional crystal structure of a binary superlattice that could not be resolved by TEM only. The structure with a [PbSe]6[CdSe]19 stoichiometry has no analogue in the atomic world. Moreover we will show how tomography can overcome the clouding effects of planar defects on structure identification by TEM

Interplay between pore size and nanoparticle spatial distribution: consequences for the stability of CuZn/SiO2 methanol synthesis catalysts

Particle growth is a major deactivation mechanism for supported metal catalysts. This study reveals that the impact of pore size on catalyst stability is very sensitive to the nanoscale metal distribution. A set of ex-nitrate CuZn/SiO2 catalysts was synthesised using SiO2-gel supports (pore size 5-23 nm). The catalyst compositions were adjusted to attain series of catalysts with either constant pore volumetric (1.6 Cu nm-3) or surface (2.0 Cu nm-2) overall metal loading. The procedures of thermal decomposition of the metal nitrate precursors were adjusted to achieve <10 nm Cu particles displaying markedly different nanospatial distributions, i.e either gathered in high-metaldensity domains with small interparticle spacings or evenly distributed over the support with maximum interparticle spacings. Under industrially relevant methanol synthesis conditions, a strong increase of the deactivation rate with the support pore size is observed for catalysts with high-density domains of Cu particles. For these samples the local, nanoscale Cu surface loading is determined by pore size rather than by the overall metal content, as ascertained by HAADF-STEM/EDX. Conversely, Cu nanoparticles evenly spaced on the surface of the SiO2 carrier show improved stability, being the deactivation rate chiefly independent of the support pore size. The differences in catalyst stability are ascribed to the dominance of different particle growth mechanisms. Our study highlights the significance of local, nanoscale properties for rationalizing the relevance of structural parameters such as pore size for catalyst stability

Interplay between pore size and nanoparticle spatial distribution: consequences for the stability of CuZn/SiO2 methanol synthesis catalysts

Particle growth is a major deactivation mechanism for supported metal catalysts. This study reveals that the impact of pore size on catalyst stability is very sensitive to the nanoscale metal distribution. A set of ex-nitrate CuZn/SiO2 catalysts was synthesised using SiO2-gel supports (pore size 5-23 nm). The catalyst compositions were adjusted to attain series of catalysts with either constant pore volumetric (1.6 Cu nm-3) or surface (2.0 Cu nm-2) overall metal loading. The procedures of thermal decomposition of the metal nitrate precursors were adjusted to achieve <10 nm Cu particles displaying markedly different nanospatial distributions, i.e either gathered in high-metaldensity domains with small interparticle spacings or evenly distributed over the support with maximum interparticle spacings. Under industrially relevant methanol synthesis conditions, a strong increase of the deactivation rate with the support pore size is observed for catalysts with high-density domains of Cu particles. For these samples the local, nanoscale Cu surface loading is determined by pore size rather than by the overall metal content, as ascertained by HAADF-STEM/EDX. Conversely, Cu nanoparticles evenly spaced on the surface of the SiO2 carrier show improved stability, being the deactivation rate chiefly independent of the support pore size. The differences in catalyst stability are ascribed to the dominance of different particle growth mechanisms. Our study highlights the significance of local, nanoscale properties for rationalizing the relevance of structural parameters such as pore size for catalyst stability

Synthesis and characterization of {Mo72Fe30}-coated large hexagonal gibbsite γ-Al(OH)3 platelets

The polyoxometalates or POMs (clusters comprising at least two metal and many oxygen atoms) have recently gained significant interest owing to their versatile architecture and especially their catalytic activities. Due to their high catalytic activity but low surface area, there is always a demand for making high surface area POMs. This work demonstrates the attachment of the anionic {Mo72Fe30} POMs to gibbsite nanoplatelets with a residual positive charge to form large surface area composites. The resulting composite reported here has been characterized using cryo-TEM imaging, EDX/STEM (elemental) analysis, ATR-IR spectroscopy, SAXS, electrophoretic mobility determination and XRD. The composite reported here could find application in catalysis

Ruthenium-decorated lipid vesicles: light-induced release of [Ru(terpy)(bpy)(oh2)]2+ and thermal back coordination

Electrostatic forces play an important role in the interaction between large transition metal complexes and lipid bilayers. In this work, a thioether-cholestanol hybrid ligand (4) was synthesized, which coordinates to ruthenium(II) via its sulfur atom and intercalates into lipid bilayers via its apolar tail. By mixing its ruthenium complex [Ru(terpy)(bpy)(4)]2+ (terpy = 2,2′;6′,2′′-terpyridine; bpy = 2,2′-bipyridine) with either the negatively charged lipid dimyristoylphosphatidylglycerol (DMPG) or with the zwitterionic lipid dimyristoylphosphatidylcholine (DMPC), large unilamellar vesicles decorated with ruthenium polypyridyl complexes are formed. Upon visible light irradiation the ruthenium−sulfur coordination bond is selectively broken, releasing the ruthenium fragment as the free aqua complex [Ru(terpy)(bpy)(OH2)]2+. The photochemical quantum yield under blue light irradiation (452 nm) is 0.0074(8) for DMPG vesicles and 0.0073(8) for DMPC vesicles (at 25 °C), which is not significantly different from similar homogeneous systems. Dynamic light scattering and cryo-TEM pictures show that the size and shape of the vesicles are not perturbed by light irradiation. Depending on the charge of the lipids, the cationic aqua complex either strongly interacts with the membrane (DMPG) or diffuses away from it (DMPC). Back coordination of [Ru(terpy)(bpy)(OH2)]2+ to the thioether-decorated vesicles takes place only at DMPG bilayers with high ligand concentrations (25 mol %) and elevated temperatures (70 °C). During this process, partial vesicle fusion was also observed. We discuss the potential of such ruthenium-decorated vesicles in the context of light-controlled molecular motion and light-triggered drug delivery

Electron Tomography Resolves a Novel Crystal Structure in a Binary Nanocrystal Superlattice

The self-assembly of different nanocrystals into a binary superlattice is of interest for both colloidal science and nanomaterials science. New properties may emerge from the interaction between the nanocrystal building blocks that are ordered in close contact in three dimensions. Identification of the superlattice structure including its defects is of key interest in understanding the electrical and optical properties of these systems. Transmission electron microscopy (TEM) has been very instrumental to reach this goal but fails for complex crystal structures and buried defects. Here, we use electron tomography to resolve the three-dimensional crystal structure of a binary superlattice that could not be resolved by TEM only. The structure with a [PbSe]6[CdSe]19 stoichiometry has no analogue in the atomic world. Moreover we will show how tomography can overcome the clouding effects of planar defects on structure identification by TEM