A. V. Petrov

A new preservation solution for lung transplantation: Evaluation in a porcine transplantation model

BACKGROUND Lung preservation injury is still a major problem in lung transplantation. The aim of the current study was to evaluate the effects of a new preservation solution (Custodiol-N) for lung preservation. METHODS Using an in vivo pig model, 7 lungs each were preserved for 24 hours after perfusion with: low-potassium dextran (LPD) solution as control (Group I); base solution of Custodiol-N without iron chelators (Group II); Custodiol-N (Group III); or Custodiol-N supplemented with dextran 40 (Group IV). Four animals received a sham operation. After left lung transplantation and contralateral lung exclusion, hemodynamics and blood gases were monitored for 6 hours; tissue samples were taken at the end of the experiments. RESULTS All animals survived the transplantation procedure. Base solution- and Custodiol-N-preserved lungs (Groups II and III) showed graft function similar to that of LPD-preserved lungs (Group I), showing a trend toward improved values. Custodiol-N with dextran (Group IV) led to a significant reduction of mean pulmonary arterial pressure (20 ± 2 vs 28 ± 3 mm Hg, p < 0.01) and pulmonary vascular resistance (410 ± 51 vs 588 ± 83 dyne/s/cm(5), p < 0.01), and oxygenation ratio was significantly higher (536 ± 52 vs 313 ± 107 mm Hg at 6 hours, p < 0.01) and PCO(2) values were significantly lower (51 ± 9 vs 77 ± 5 mm Hg at 6 hours, p < 0.01) at 6 hours compared with LPD (Group I). Custodiol-N (Groups II to IV) showed a trend toward a lower wet/dry ratio and reduced oxidative stress; in the presence of dextran (Group IV), the difference was again statistically significant, when compared with LPD (Group I). CONCLUSIONS Custodiol-N solution is a new alternative preservation solution for lung transplantation that offers significantly superior protection compared with LPD when dextran 40 is added.

Electronic structure of fluorite-type crystals

The results of the electronic structure calculations made in the large-unit-cell complete neglect of differential overlap approach are given for the crystals MF2 (M=Ca, Sr, Ba, Cd, Pb or Sn) and PbSnF4. The same approach is used for the impurity centre MF2:Cd (M=Ca, Sr, Ba and Pb) and the lattice distortion introduced by the symmetrical shift of the nearest cation neighbour. It is shown that the influence on the band structure of this lattice distortion is not large.

Structural features and transport processes of superionic conductors based on tin(II) fluoride

The thermal behavior and transport properties of lead(II) tetrafluorostannate(II) have been investigated by impedance spectroscopy,19F NMR and high hydrostatic pressure techniques. It is shown that these experimental methods are powerful tools to clarify ionic transport processes in the investigated solid electrolytes with predominant fluorine mobility.

Molecular dynamics simulation of silver bromide nanostructures in single-walled carbon nanotubes

Nanostructures formed upon filling single-walled carbon nanotubes of different diameters (ranging from 11.5 to 17.6 Å) with silver bromide have been investigated using the molecular dynamics method. The results of molecular dynamics computer simulation have demonstrated that, in such tubes, AgBr nanotubes in the form of rolled-up two-dimensional crystalline networks (including structures both with a trigonal coordination and with a tetragonal coordination of ions) can be produced as well as fragments of the NaCltype structure, which is typical of bulk AgBr crystals. In the initial stage of their filling, the carbon nanotubes in the silver bromide melt are deformed, on average, to a greater extent than those in a similar system with AgI. After taking out from the melt, the degree of deformation of the nanotubes decreases and, in the majority of cases, AgBr nanotubular structures based on a hexagonal network are formed inside them.

Computer simulation of AgI nanostructures in single-wall carbon nanotubes

Nanostructures resulting from the incorporation of silver iodide into single-wall carbon nanotubes (SWCNTs) of various diameters have been studied using molecular dynamics simulation. The results indicate the formation of single-wall silver iodide nanotubes when the SWCNT diameter is within 14.2 Å, whereas thicker carbon tubes contain, in addition, an axial “filament” of silver and iodide ions. AgI nanotubes in SWCNTs typically have a hexagonal structure (with the ions in trigonal coordination).

Electronic Structure of Fullerene Derivatives with Malonic Acid Fragments

The electronic structure of fullerene C60 derivatives containing malonic acid fragments used as dopants in nanocomposite polymer electrolytic membranes was calculated by the density functional method. Charge states of atoms, thus determined, are necessary for molecular-dynamic simulation of proton mobility in these membranes.

Exfoliation, point defects and hydrogen storage properties of monolayer TiS3: an ab initio study

The possibility of H2 molecule adsorption on the basal plane of monolayer TiS3 at various sites has been studied. Among the studied adsorption sites, few sites were found to be suitable for physisorption with binding energy up to 0.10 eV per H2. To increase the activity of hydrogen sorption, the possibility of generating S-vacancies, by removing sulfur atoms from the basal plane of monolayer TiS3, was investigated. Despite the fact that the structures containing vacancies were found to be stable enough, there was no increase in the activity towards hydrogen adsorption. The same effect was obtained with the use of common methods of increasing of the H2 adsorption energy: the decoration of the two-dimensional material with alkali metals (Li, Na). This might be caused by the negatively charged surfaces of single layer TiS3, which hinder the increase in binding by alkali metals through a weak electrostatic interaction.

Geometry and electronic structure of (SiO 2 ) 3 clusters

Electronic structure of (SiO2)3 clusters was calculated by the density functional method. Charge states were determined using various functionals, bond lengths and total energies of clusters were estimated.

Molecular dynamics simulation of SnF2 nanostructures in the internal channels of single-walled carbon nanotubes

A molecular dynamics simulation of solid tin(II) fluoride nanostructures formed in internal channels of single-walled carbon nanotubes (SWCNTs) has been performed using two types of model potentials—without and with inclusion of the polarization of ions. For the potential taking into account the polarization of ions, an ordered SnF2@SWCNT structure is reproduced: in SWCNT(10, 10), it has the form of the SnF2 internal nanotube. At the same time, the SnF2@SWCNT(11,11) structure is substantially disordered (glass-like). It has been found that heating of the SnF2@SWCNT model system produces a superionic state characterized by a high mobility of fluorine ions without migration of tin ions. The model potentials disregard the covalent character of Sn-F bonds and the specific interactions of a lone electron pair of the Sn2+ ion. This makes it impossible to completely reproduce the properties of SnF2 at normal pressures. However, some characteristics of the SnF2 high-pressure modification can be reproduced if the polarization of ions is taken into account.

Electronic structure of lead (II) fluoride and lead (II) chloride crystals

The method of complete neglect of differential overlap was used to calculate the electronic structure of α PbF2, β PbF2, and PbCl2 crystals which form the basic matrices for the synthesis of new superionic conductors. It was shown that the electronic subsystem is fairly stable on transition from the high-symmetry β PbF2 crystal to the low-symmetry α PbF2. The electronic structure of the cotunnite crystal PbCl2 was calculated for the first time.