Polymers with silicon-carbon chains framed by silacycloalkane groups

We have synthesized spiran compounds with the silicon-carbon heterocycles and their analogs with alkyl radicals; and also the tricyolic compound. Their heat-induced polymerization and the properties of the resulting polymers have been investigated. The influence of the groups framing the main chain of the polymers on the stability of the chain to thermal oxidation and on its flexibility has been studied.     

Convolutions, Transforms, and Convex Bodies

The paper studies convex bodies and star bodies in Rⁿ by usingRadon transforms on Grassmann manifolds, p-cosine transformson the unit sphere, and convolutions on the rotation group ofRⁿ. It presents dual mixed volume characterizations of i-intersectionbodies and L_p-balls which are related to certain volume inequalitiesfor cross sections of convex bodies. It considers approximationsof special convex bodies by analytic bodies and various finitesums of ellipsoids which preserve special geometric properties.Convolution techniques are used to derive formulas for mixedvolumes, mixed surface measures, and p-cosine transforms. Theyare also used to prove characterizations of geometric functionals,such as surface area and dual quermassintegrals. 1991 MathematicsSubject Classification: 52A20, 52A40.     

Excited states dynamics under high pressure in lanthanide-doped solids

Emission related to rare earth ions in solids takes place usually due to 4fⁿ→4fⁿ and 4fⁿ⁻¹5d¹→4fⁿ internal transitions. In the case of band to band excitation the effective energy transfer from the host to optically active impurity is required. Among other processes one of the possibilities is capturing of the electron at the excited state and the hole at the ground state of impurity.The latest results on high pressure investigations of luminescence related to Pr³⁺ and Eu²⁺ in different lattices are briefly reviewed. The influence of pressure on anomalous luminescence and 4fⁿ⁻¹5d¹→4fⁿ luminescence in BaSrF₂:Eu²⁺ and LiBaF₃:Eu²⁺ systems and Pr³⁺ 4fⁿ→4fⁿ emission quenching is presented and discussed. A theoretical model describing the impurity-trapped exciton as a system where a hole is localized at the impurity and an electron is captured by Coulomb potential at Rydberg-like states is developed. The results show the importance of local lattice relaxation for the creation of stable impurity-trapped exciton states. The ligands shifts create a potential barrier that controls the effect of mixing between the Rydberg-like electron and localized electron wave functions.     

Influence of high hydrostatic pressure on Eu-luminescence in KMgF3:Eu crystal

Spectroscopic investigations are presented of KMgF₃:Eu²⁺ crystal under high hydrostatic pressure from ambient to 310 kbar. The sample was excited by 30 ps pulses generated by optical parametric generator (OPG) system with wavelength controlled between 210 and 325 nm. The Grüneisen parameters of individual phonons are obtained from the pressure shift of the Eu²⁺ emission related to the ⁶P_7/2→⁸S_7/2 transition accompanied by phonon sideband. The luminescence decays exponentially for the pressure below 135 kbar with lifetime of 3.30 ms and slightly nonexponential above 135 kbar, while the average decay time is nearly independent of the pressure. The results obtained for KMgF₃:Eu²⁺ are compared with those for LiBaF₃:Eu²⁺ in which the ⁶P_7/2→⁸S_7/2 emission is replaced by the broadband emission of the 4f⁶5d¹→4f⁷ transition at high hydrostatic pressure.     

Application of vegetable oils for electrocatalytic synthesis of hydrocarbons

Conditions of Kolbe cross-electrosynthesis of 10-undecylenic and acetic acids are studied on different catalyst anodes. It is shown that the key anodic process stages are the stages of formation of vinyl radicals from anions of unsaturated and methyl radicals under electrosynthesis of acetate anions. As dependent on the conditions of the process, the main product formed on the anode of the Pt-10% Ir alloy is either hydrocarbon CH₃CH₂CH(CH₃)(CH₂)7CH₂CH₃ (58 wt %) being the product of addition of three methyl radicals to a vinyl radicals or olefin CH₂=CH(CH₂)₇CH₂CH₃ (57 wt %) being the product of dimerization of vinyl and methyl radicals.     

Antibody modified Bovine Serum Albumin microspheres for targeted delivery of anticancer agent Gemcitabine

Inhibition of the EGFR signaling pathway is one of the attractive therapeutic targets for pancreatic cancer as recent studies demonstrated that EGFR is over‐expressed in pancreatic cancer. In this article we have demonstrated the design of targeted drug delivery system containing Bovine Serum Albumin (BSA) microspheres as delivery vehicle, gemcitabine as anticancer drug and anti‐EGFR (epidermal growth factor receptor) monoclonal antibody as targeting agent. The conjugated BSA microspheres were characterized by several physico‐chemical techniques such as scanning electron microscope, optical microscopy, fluorescent microscopy etc. Administration of these BSA microspheres containing gemcitabine and anti‐EGFR (BSA‐Gem‐EGFR) shows significant inhibition of pancreatic cancer cells (AsPC1) compared to the cells treated with only BSA microspheres, BSA with gemcitabine (BSA‐Gem), and free gemcitabine. This strategy could be used as a generalized approach for the treatment of pancreatic cancer along with other cancers which overexpress EGFR on cell surface. Copyright © 2012 John Wiley & Sons, Ltd.     

Luminescence kinetics in silica gel doped with Tb3+ ions and ZnS:Mn2+ nanocrystals

Luminescence kinetics and time-resolved luminescence spectra of SiO₂, SiO₂ doped with ZnS:Mn²⁺ nanocrystals and SiO₂ doped with ZnS:Mn²⁺, and additionally co-doped with Tb³⁺, are presented. The purposes of the paper are the analysis of the kinetics of the Tb³⁺ and Mn²⁺ intra-shell luminescence and the elucidation of the energy-transfer mechanism between the ZnS:Mn²⁺ nanocrystals and the Tb³⁺ ions. We have found a blue luminescence related to defects in the ZnS nanocrystals and an intrinsic luminescence of the SiO₂ lattice, which decays in few ns. A yellow luminescence related to the Mn^{2+ 4}T₁(G)→⁶A₁ transition and yellow sharp lines related to the ⁵D₄→⁷F₆, ⁷F₅, ⁷F₄ and ⁷F₃ transitions in Tb³⁺ are found to decay in ms. A very effective energy transfer between ZnS:Mn²⁺ nanoparticles and Tb³⁺ ions has been observed.     

ChemInform Abstract: The Ground-State Potential Energy Surface of Diazene

has been studied by using a complete active space MCSCF wave function generated by distributing eight electrons among eight orbitals.