Ionic conductances in water-sulfolane mixtures at 30°C

Conductances of solutions of triisoamyl-n-butylammonium (iAm₃BuN⁺) iodide and sodium tetraphenylboride, iodide, and bromide have been measured in water-sulfolane mixtures at 30°C. Experimental data were analyzed by the 1965 Fuoss-Onsager-Skinner equations. The limiting equivalent conductances of triisoamyl-n-butylammonium tetraphenylboride (iAm₃BuNBPh₄) in each solvent mixture were obtained by the equation $$\Lambda _0 (iAm_3 BuNBPh_4 ) = \Lambda _0 ({\text{i}}Am_3 BuNI) + \Lambda _0 (NaBPh_4 ) - \Lambda _0 (NaI)$$ Limiting ionic equivalent conductances in water-sulfolane mixtures were calculated on the assumption thatι ₀(iAm ₃ BuNBPh ₄)/2λ₀(iAm ₃ BuN ⁺)=λ₀(BPh _- ⁴ ). The variations of the limiting ionic Walden product with solvent composition are discussed with respect to current information concerning solvent structural effects and ion-solvent interaction.     

High-throughput optics for X-ray astronomy (*)(**)

Summary High-throughput X-ray optics are required for future X-ray astronomy missions. These optics are composed of a large number of nested confocal mirrors with very thin thickness in order to reduce the losses due to the obstruction of the mirrors wall and to keep the weight within acceptable values. The replica technique by electroforming the mirrors from mandrels provides a cost-effective solution for the manufacture of these X-ray optical systems. In the paper is reported the application of the electroforming process for the fabrication of the X-ray imaging concentrators for the SAX project and for the JET-X X-ray telescope. Moreover some considerations are given concerning a possible use of more elaborated electroforming processes for manufacturing light-weight large-aperture X-ray optics. To speed up publication, the proofs were not sent to the authors and were supervised by the Scientific Committee.     

Analysis of the A1

We develop a unitary isobar model, and apply it to a study of partial wave analyses of the available three-pion and $\text{K}{}^1\text{K}$ data.     

General requirements for a dedicated observing system in a systematic search for superfast pulsars

Summary The observational panorama about radio pulsars is Briefly rewieved with emphasis on those selection effects which could have linited the detection of a class of fast and superfast pulsars. Some technical requirements useful to reduce these effects are taken in consideration and discussed. Paper presented at the 2^o Convegno Nazionale di Fisica Cosmica, held at L'Aquila, 29 May–2 June 1984.     

The conductance of tetrabutylammonium salts in water-sulfolane mixtures at 30°C

Conductance measurements are reported for Bu ₄ NCl, Bu ₄ NBr, Bu ₄ NI, and Bu ₄ NClO ₄ at 30°C in water-sulfolane mixtures over the entire solvent composition range. Experimental data were analyzed by the 1965 Fuoss-Onsager-Skinner equation. The limiting equivalent conductances in water and in sulfolane were compared with literature values. The trends of the Walden products are discussed in terms of water structural changes caused by addition of sulfolane. As expected, on the basis of previous results reported in the literature, a significant amount of association was detected for Bu ₄ NI in water. Very small association constants were also found for Bu ₄ NI and Bu ₄ NClO ₄ at 10 wt.% sulfolane.     

Urea solid-state biosensor suitable for continuous dialysis control

A solid state potentiometric biosensor for urea determination was assembled coupling a nonactin-based ISE without an internal solution with immobilized urease. The system proved to be useful for continuous monitoring of urea during dialysis treatment using the ultrafiltrate of blood as sample. A noticeable shift of potential occurred during the dialysis (probably due to continuous extraction of ionophore by the ultrafiltrate). Therefore a flow injection analysis assembly was necessary to control the shift of electrode potential.     

Photo-Induced Microfluidic Production of Ultrasmall Glyco Gold Nanoparticles

Ultra-small gold nanoparticles (UAuNPs) are extremely interesting for applications in nanomedicine thanks to their good stability, biocompatibility, long circulation time and efficient clearance pathways. UAuNPs engineered with glycans (Glyco-UAuNPs) emerged as excellent platforms for many applications since the multiple copies of glycans can mimic the multivalent effect of glycoside clusters. Herein, we unravel a straightforward photo-induced synthesis of Glyco-UAuNPs based on a reliable and robust microfluidic approach. The synthesis occurs at room temperature avoiding the use of any further chemical reductant, templating agents or co-solvents. Exploiting ¹H NMR spectroscopy, we showed that the amount of thiol-ligand exposed on the UAuNPs is linearly correlated to the ligand concentration in the initial mixture. The results pave the way towards the development of a programmable synthetic approach, enabling an accurate design of the engineered UAuNPs or smart hybrid nano-systems.     

Characterization and catalytic activity of iron(III) mono(4-N-methyl pyridyl)-tris(halophenyl) porphyrins in homogeneous and heterogeneous systems

The synthesis, characterization and catalytic activity of the cationic iron porphyrins Fe[M(4-N-MePy)TDCPP]Cl₂ and Fe[M(4-N-MePy)TFPP]Cl₂ in the epoxidation of (Z)-cyclooctene by PhIO in homogeneous solution and supported on silica gel (SG), imidazole propyl gel (IPG) or SG modified with 2-(4-sulfonatophenyl)ethyl groups (SiSO₃) have been accomplished. When supported on IPG, both cationic FeP bind to the support via Fe–imidazole coordination. Fe[M(4-N-MePy)TDCPP]IPG contains a mixture of low-spin bis-coordinated Fe^IIIP and high-spin mono-coordinated Fe^IIIP species, whereas Fe[M(4-N-MePy)TFPP]IPG only contains high-spin mono-coordinated Fe^IIIP. These FePIPG catalysts also contain Fe^IIP species, whose presence was confirmed by EPR spectroscopy using NO as a paramagnetic probe. Both cationic FePs coordinate to SG through Fe–O ligation and they are present as high-spin Fe^IIIP species. The cationic FePs supported on SiSO₃⁻ are also high-spin Fe^IIIP species and they bind to the support via electrostatic interaction between the 4-N-methylpyridyl groups and the SO₃⁻ groups present on the matrix. In homogeneous solution, both Fe[M(4-N-MePy)TDCPP]Cl₂ and Fe[M(4-N-MePy)TFPP]Cl₂ have similar catalytic activity to Fe(TDCPP)Cl and Fe(TFPP)Cl, leading to cis-epoxycyclooctane yields of 92%. When supported on inorganic matrices, both FePs lead to epoxide yields comparable to their homogeneous analogues and their anchoring enables catalyst recovery and re-use. Recycling of Fe[M(4-N-MePy)TDCPP]SiSO₃⁻ shows that this FeP maintains its activity in a second reaction.