Developed smectics: when exact solutions agree

In the limit where the bending modulus vanishes, we construct layer configurations with arbitrary dislocation textures by exploiting a connection between uniformly spaced layers in two dimensions and developable surfaces in three dimensions. We then show how these focal textures can be used to construct layer configurations with finite bending modulus.     

Stabilization of Titanium Dioxide Nanoparticles at the Surface of Carbon Nanomaterials Promoted by Microwave Heating

TiO₂ is frequently combined with carbon materials, such as reduced graphene oxide (RGO), to produce composites with improved properties, for example for photocatalytic applications. It is shown that heating conditions significantly affect the interface and photocatalytic properties of TiO₂@C, and that microwave irradiation can be advantageous for the synthesis of carbon‐based materials. Composites of TiO₂ with RGO or amorphous carbon were prepared from reaction of titanium isopropoxide with benzyl alcohol. During the synthesis of the TiO₂ nanoparticles, the carbon is involved in reactions that lead to the covalent attachment of the oxide, the extent of which depends on the carbon characteristics, heating rate, and mechanism. TiO₂ is more efficiently stabilized at the surface of RGO than amorphous carbon. Rapid heating of the reaction mixture results in a stronger coupling between the nanoparticles and carbon, more uniform coatings, and smaller particles with narrower size distributions. The more efficient attachment of the oxide leads to better photocatalytic performance.     

Soft x-ray absorption of FePS3 and NiPS3

With the partial yield technique we measured the absorption spectra of several core levels in FePS₃ and NiPS₃. The M_{2, 3} spectra of Fe and Ni are interpreted as localized transitions 3p⁶3d^m?3p⁵ 3d^m+1 of the transition metal ion, split into a multiplet by final state multiconfiguration interaction. The P L_{2, 3}, S L_{2, 3}, and S L₁ spectra are similar to each other and are interpreted in terms of the projected density of states of the conduction bands derived from the states of the (P₂S₆)^4? cluster.     

Resolution of an iridoid synthon, gastrolactol, by means of dynamic acetylation and lipase-catalyzed alcoholysis

A short synthetic route to asymmetric iridoids was developed. The three key steps were an intramolecular [4 + 2] cycloaddition reaction of an enamine derivative of 8-oxocitral (2), a dynamic acetylation, and an enzymatic resolution of the gastrolactyl acetates 5a and 5b, iridoids with three stereocenters. Some regio- and stereoselective heterogeneous catalytic hydrogenations of double bonds in iridoid aglucones were discussed.     

Correlation between carbon nanotube microstructure and their catalytic efficiency towards the p-coumaric acid degradation

Pristine and annealed multi-walled C nanotubes are preliminarily tested as catalysts towards the degradation of p-coumaric acid with better performances than the widely used activated carbon. In order to clarify the origin of their different catalytic efficiency, the samples are analysed by means of high-resolution transmission electron microscopy, X-ray photoemission, reflection electron energy loss and micro-Raman spectroscopy. Chemical composition, mass density, bonding configurations and threefold- to fourfold-coordinated carbon bonding ratios are determined. The comparative discussion of the results obtained leads to attribute the higher catalytic activity of the pristine nanotubes to their larger sp²/sp³ carbon bonding fraction and greater amount of oxygen containing functional groups.     

Approximating functions in hydrology of unsaturated soils—II

Summary Analytical expressions of conductivity and diffusivity have been obtained for an unsaturated sandy soil in the whole range of admissible values of volumetric water content. Besides fitting experimental values they satisfy a set of relations which guarantee that unphysical situations cannot be reached. The matric potential has been obtained by the numerical integration of a known relation which connects conductivity, diffusivity and matric potential.

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Riassunto Per un suolo sabbioso non saturo sono state ottenute delle espressioni analitiche della conducibilità idraulica e della diffusività per tutto l'intervallo di valori che il contenuto di acqua può assumere. Oltre ad approssimare i valori sperimentali, queste espressioni soddisfano alle condizioni imposte per garantire che non vengano raggiunte situazioni non fisiche. Il potenziale di matrice è stato ottenuto dalla integrazione numerica di una nota espressione analitica che lega tra loro conducibilità, diffusività e potenziale di matrice.

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Резюме Получаются аналитические выражения для проводимости и температуропроводности для ненасьщенных песчаных почв во всей области допустимых значений обьемных концентраций воды. Эти выражения аппроксимируют экспериментальные данные, а также удовлетворяют системе соотношений, которые гарантируют, что нефизические ситуации не могут возникать. Получается матричный потенциал с помощью численного интегрирования известного соотношения, которое связывает проводимость, температуропроводность и матричный потенциал.