Liposomi rivastigmina za isporuku u mozak intranazalnim putem

The present study is mainly aimed at delivering a drug into the brain via the intranasal route using a liposomal formulation. For this purpose, rivastigmine, which is used in the management of Alzheimer’s disease, was selectd as a model drug. Conventional liposomes were formulated by lipid layer hydration method using cholesterol and soya lecithin as lipid components. The concentration of rivastigmine in brain and plasma was studied in rat models after intranasal and oral administration of liposomes and free drug. A significantly higher level of drug was found in the brain with intranasal liposomes of rivastigmine compared to the intranasal free drug and the oral route. Intranasal liposomes had a longer half-life in the brain than intranasally or orally administered free drug. Delivering rivastigmine liposomes through the intranasal route for the treatment of Alzheimer’s disease might be a new approach to the management of this condition.Glavni cilj rada je razvoj liposoma za intranazalnu primjenu za isporuku lijeka u mozak. U tu svrhu izabran je rivastigmin kao modelni lijek koji se upotrebljava u terapiji Alzheimerove bolesti. Liposomi su pripravljeni metodom hidratacije lipidnog sloja koristeći kolesterol i lecitin iz soje kao lipidne komponente. Praćena je koncentracija rivastigmina u mozgu i plazmi nakon intranazalne i peroralne primjene liposoma i slobodnog lijeka. S intranazalnim liposomima rivastigmina postignuta je značajno veća koncentracija lijeka u mozgu. Osim toga intranazalni liposomi imaju dulje vrijeme poluživota u mozgu. Intranazalna primjena liposoma rivastigmina mogla bi predstavljati novi pristup terapiji Alzheimerove bolesti

Choice of the electronic basis for field-induced surface hopping

A method combining an Ehrenfest-like approach, which minimizes the number of surface hops, with Tully's fewest switches surface hopping is proposed for the description of nonadiabatic molecular dynamics in the presence of an external electromagnetic field. When two states are strongly coupled by the applied light field, an Ehrenfest-like approach is employed, which allows the system to be in a coherent superposition. Tully's fewest switches surface hopping (FSSH) is used for the weak- and no-coupling regimes to improve the asymptotic behavior of the method. The decision of which approach to employ at a given time is made based on a simple analysis of Rabi oscillations in a two-state model. The method is tested for two exactly solvable model systems, i.e., a stimulated emission scenario in a pulsed laser field and a photoexcitation scenario in a cw laser field. Position and momentum densities of the nuclei compare well with exact quantum dynamics simulations and improve on both a pure Ehrenfest and a pure FSSH approach. The method is efficient and easily implemented

Infrared-laser-pulse-enhanced ultrafast fragmentation of N22+N_2^{2+} following Auger decay: Mixed quantum-classical simulations

We employ mixed quantum-classical molecular dynamics simulations to investigate the fragmentation of $N_2$ molecules after core-level photoionization by an x-ray laser, subsequent Auger decay, and followed by a femtosecond IR pulse that interacts with $N_2^{2+}$. The delayed IR pulse couples the dissociative electronic states of $N_2^{2+}$ with electronic states that can support long-lived vibrational resonances. We compare our simulations with previous quantum dynamics calculations in a quasidiabatic representation, which employed a small number of electronic states. Good agreement for both the Auger spectrum as well as the influence of the delayed IR pulse is found. By employing the mixed quantum-classical treatment, we can greatly reduce the computational cost to simulate the fragmentation dynamics compared to the quantum dynamics simulations. Furthermore, we reinvestigate the title process by employing an extended set of adiabatic potential energy surfaces and also investigate the role of nonadiabatic coupling in the process. The use of the full set of adiabatic potentials increases the dissociation probability and changes the details of the interaction with the IR pulse, but no effect due to the nonadiabatic coupling is found

Ferroelectric domain structure studies on PbTiO3 single crystals by polarizing microscope, SEM and AFM

Ferroelectrics2311 -4 pt 3637/49 - 642/54FERO

Growth and characterization of Pb1-xCaxTiO3 single crystals by self-flux technique

Materials Chemistry and Physics573281-284MCHP

Field-enabled quantum interference in atomic Auger decay

We demonstrate that an external terahertz (THz) field enables the formation of interference between two distinct Auger pathways leading to the same final ionic state. The kinetic energy of Auger electrons ejected from either of two spin-orbit split one-hole states of magnesium cations is recorded. In the presence of the THz field, a clear oscillatory structure in the Auger spectrum emerges, which we find to be in very good agreement with an analytical model based on perturbation theory. For this interference to occur, the THz field has to chirp the energy of both Auger electrons and photoelectrons simultaneously, in order to create states with indistinguishable quantum properties