Capillary electrochromatography without external pressure assistance. Use of packed columns with a monolithic inlet frit

A fused silica capillary column was packed with RP(18) silica stationary phase entrapping the particles between two frits obtained by two different procedures. The inlet frit consisted of a short organic polymer made via a thermopolymerization process while the outlet frit was prepared by sintering the octadecylsilica (ODS) material. The packed column was employed in capillary electrochromatography (CEC) experiments for the separation of three selected test compounds. Retention time and separation efficiency were evaluated. Results were compared with those ones obtained with a packed capillary containing the same stationary phase entrapped between two sinterized frits. The novel packed column exhibited comparable separation efficiency and resolution with the traditional one. However, it allowed experiments without pressure support during the runs with no bubble formation.     

Intercalation of tris-(2,2′-bipyridyl) ruthenium (II) in α- and γ-zirconium phosphate: synthesis, thermal behaviour and X-ray characterization

Intercalation compounds such as the ruthenium trisbipyridyl complex in inorganic layered ion-exchangers (α- and γ-zirconium phosphate) have been synthesized using the batch method. There is no loss of bipyridyl ligand from the metal ion during the exchange of the ruthenium trisbipyridyl complex in these host matrices. The materials obtained are thermally stable up to ~330 °C (γ-phase) or ~380 °C (α-phase). The complex decomposition occurs in one or more steps and at ~600 °C the complex decomposition is complete. The X-ray patterns of ruthenium materials show a new phase with an increase in the interlayer distance with respect to the initial phase. Microanalysis measurements confirm the fact that the ruthenium complex is not modified when exchanged and the complex decomposition depends on its position in the host matrices.     

The Relevance of the Collaborative Effect in Determining the Performances of Photorefractive Polymer Materials

A derivative of 2‐methylindole, 3‐[2‐(4‐nitrophenyl)ethenyl]‐1‐allyl‐2‐methylindole, NPEMI‐A, is studied for its photoconductivity and photorefractivity behaviour. Its blends with the organic polymer poly‐(2,3‐dimethyl‐N‐vinylindole), PVDMI, are also investigated. Due to the expected and devised mutual solubility of the two components of the blends, it is possible to carry out measurements with the weight percent of the chromophore NPEMI‐A changing from zero to 100. Films were produced by a squeezing process between two ITO‐covered glass sheets. No opacity phenomena, that are so common for many other organic blends due to the segregation of the dissolved chromophore, are observed. The photorefractive optical gain Γ₂ is obtained as a function of the chromophore content. Differential scanning calorimetry measurements (DSC) are also carried out to obtain the whole change of the glass transition temperature T_g as a function of the amount of chromophore contained in the blends. From the experimental trend of T_g a meaningful quantitative estimate of the value of the electrostatic interactions acting in the studied blends, is obtained. The importance of the value of T_g, and of the electrostatic interactions, in determining the extent of the photorefractivity is clearly evident. The results are compared for NPEMI‐A (Γ₂=210 cm^?1) and for NPEMI‐E (Γ₂ ≈ 2000 cm^?1) that has a N‐2‐ethylhexyl group instead of a N‐allyl group. The Pockels and Kerr contributions and—for the first time—a “collaborative effect” of the photorefractivity of NPEMI‐A are distinguished and quantitatively evaluated.     

Zinc ions and zinc sulfide particles in sol-gel zirconium phosphate synthesis, thermal behavior and X-ray characterization

Zinc ions can be exchanged in sol-gel zirconium phosphate by using the batch or hydrothermal method. The zinc materials obtained that undergo thermal treatment after complete dehydration, can rehydrate fully or partially depending on whether half or all the zinc ions are exchanged. At high temperature syntherization is evident. By flowing sulfide acid over the zinc forms, zinc sulfide particles are formed and their amount depends on the length of time of the gas flow and on the state of hydration of the original material. This is not the case in the half exchanged zinc zirconium phosphate material. The decomposition temperature of the ZnS particles depends on their position in the exchanger: whether on the surface or between the layers of the host matrix. The XRD patterns of the materials obtained are similar to those of the sol-gel zirconium phosphate. The presence of ZnS particles is evident.     

How Strong Is the Coordination Bond between a Histidine Tag and Ni - Nitrilotriacetate? An Experiment of Mechanochemistry on Single Molecules

Isolation of a His-tagged protein by means of a Ni - nitrilotriacetate-functionalized chromatographic matrix or biosensor was simulated in a single-molecule experiment, and the mechanochemistry-that is, the interplay between mechanical and chemical forces (shown schematically)-was studied with a scanning force microscope.     

k—Very Ample Line Bundles on Del Pezzo Surfaces

A k-very ample line bundle L on a Del Pezzo Surface is numerically characterized, improving the results of Biancofiore— Ceresa in [7].