Criteria for Carotid Atherosclerotic Plaque Instability.

Background: The study aim is to determine the criteria for carotid atherosclerotic plaque instability with the use of an advanced ultrasound technology, immunohistochemical analysis, and electron paramagnetic resonance (EPR) and assess their correlations with histologic results.

Methods: A total of 92 patients were included in the study and were examined by ultrasound duplex scanning and ultrasound elastography. Plaques harvested during carotid endarterectomy were obtained for histologic analysis, immunofluorescent assay, and EPR spectroscopic measurements.

Long-Term Results of Endovascular Treatment of Chronic Iliofemoral Venous Obstructive Lesions.

Objective: To evaluate the long-term results in endovascular treatment of iliofemoral venous obstructive lesions.

Methods: From January 2009 to March 2017, 75 patients were admitted for endovascular treatment of chronic obstructive lesions of the iliofemoral veins. Of these, 60 patients underwent stenting of postthrombotic obstructions and 15 patients stenting of nonthrombotic obstructive lesions of the iliac veins (May-Thurner syndrome in 11, for tumor-induced compression and cicatricial stenosis in 4).

First Experience of Performing Hybrid Operations in Chronic Venous Obstructions of Iliofemoral Segments in Patients With Postthrombotic Syndrome.

Objective: To assess the first results of hybrid operations in chronic venous obstructions of iliofemoral segments in patients with postthrombotic syndrome (PTS).

Methods: Hybrid operations (open endovenectomy from the common femoral vein with arteriovenous fistula creation and iliac vein stenting) were performed in 12 patients diagnosed with PTS. All of the patients were diagnosed with severe chronic venous insufficiency.

Paramagnetic Manganese in the Atherosclerotic Plaque of Carotid Arteries.

The search for adequate markers of atherosclerotic plaque (AP) instability in the context of assessment of the ischemic stroke risk in patients with atherosclerosis of the carotid arteries as well as for solid physical and chemical factors that are connected with the AP stability is extremely important. We investigate the inner lining of the carotid artery specimens from the male patients with atherosclerosis (27 patients, 42-64 years old) obtained during carotid endarterectomy by using different analytical tools including ultrasound angiography, X-ray analysis, immunological, histochemical analyses, and high-field (3.4 T) pulse electron paramagnetic resonance (EPR) at 94 GHz.

Bacterial Communities Associated with Atherosclerotic Plaques from Russian Individuals with Atherosclerosis.

Atherosclerosis is considered a chronic disease of the arterial wall and is the major cause of severe disease and death among individuals all over the world. Some recent studies have established the presence of bacteria in atherosclerotic plaque samples and suggested their possible contribution to the development of cardiovascular disease. The main objective of this preliminary pilot study was to better understand the bacterial diversity and abundance in human atherosclerotic plaques derived from common carotid arteries of individuals with atherosclerosis (Russian nationwide group) and contribute towards the further identification of a main group of atherosclerotic plaque bacteria by 454 pyrosequencing their 16S ribosomal RNA (16S rRNA) genes.

Long-term results of the monocusp valve formation in the common femoral vein in patients with avalvular deep veins of the lower extremities.

Background: Aim of the study was to evaluate the long-term results of the monocusp valve formation in the common femoral vein (CFV) in patients with avalvular deep veins (ADV) of the lower extremities.

Methods: A total of 36 patients (24 women and 12 men) at the age varying from 37 to 58 years old were given surgical treatment during the period from 2008 to 2014. Six patients presented with congenital ADV, while the remaining 30 ADV had a consequence of the post-thrombotic lesion in the valves with the complete recanalization and manifested deep venous axial reflux.

DFT study of the hydrolysis reaction in atranes and ocanes: the influence of transannular bonding.

Thermochemical kinetics of hydrolysis reactions of compounds with transannular intramolecular M…N bonds, i.e., atranes RM(OCH2CH2)3N and ocanes R2M(OCH2CH2)2NH (M = Si, Ge; R = F, Cl, Me), is studied at the B3LYP/aug-cc-pVDZ theoretical level.

Recycling of polymers: a review.

Plastics are inexpensive, easy to mold, and lightweight. These and many other advantages make them very promising candidates for commercial applications. In many areas, they have substantially suppressed traditional materials.

An assessment of DFT methods for predicting the thermochemistry of ion-molecule reactions of group 14 elements (Si, Ge, Sn).

Experimental mass-spectrometry data on thermochemistry of methide transfer reactions (CH₃)₃M(+) + M'(CH₃)₄ ↔ M(CH₃)₄ + (CH₃)₃M'(+) (M, M' = Si, Ge or Sn) and the formation energy of the [(CH₃)₃Si-CH₃-Si(CH₃)₃](+) complex are used as benchmarks for DFT methods (B3LYP, BMK, M06L, and ωB97XD). G2 and G3 theory methods are also used for the prediction of thermochemical data. BMK, M06L, and ωB97XD methods give the best fit to experimental data (close to chemical accuracy) as well as to G2 and G3 results, while B3LYP demonstrates poor performance.

Quantum chemical study of silanediols as metal binding groups for metalloprotease inhibitors.

DFT (B3LYP and M06L) as well as ab initio (MP2) methods with Dunning cc-pVnZ (n=2,3) basis sets are employed for the study of the binding ability of the new class of protease inhibitors, i.e., silanediols, in comparison to the well-known and well-studied class of inhibitors with hydroxamic functionality (HAM).

Vibrational spectra of silatranes and germatranes XM(OCH₂CH₂)₃N (X=F,Cl,H; M=Si,Ge). The problem of the theoretical prediction of condensed phase spectra.

The structures of silatranes and germatranes XM(OCH(2)CH(2))(3)N (X=F,Cl,H; M=Si,Ge) were optimized and their vibrational spectra were calculated at the B3LYP/aug-cc-pVDZ level of theory. Theoretical frequencies of vibrations perpendicular to the C(3) axis (E type) are in good agreement with experimental values, while the axial vibrations (MX and M..

Effect of substituents and hydrogen bonding on barrier heights in dehydration reactions of carbon and silicon geminal diols.

Activation barrier heights for the dehydration reaction of geminal carbinols and silanediols R'R″X(OH)(2) (X = C, Si) were estimated at the B3LYP and MP2 levels of theory employing Dunning's correlation-consistent triple-zeta basis sets. It was shown that the barrier height for carbon derivatives steadily decreases upon substitution by R groups, usually termed as electron-donating, such as alkyl and amino groups. Substitution by electron-withdrawing groups leads, however, only to small changes in barrier heights compared to that of methanediol.

Theoretical study of the mechanisms of the hydrolysis and condensation reactions of silicon and titanium alkoxides: similarities and differences.

Stationary states for hydrolysis reactions in M(OCH(3))(4) + nH(2)O (M = Si, Ti; n = 1-3) systems are optimized at the B3LYP and MP2 levels with the Wachters basis set for titanium and the cc-pVDZ set for other atoms. Geometries of these states for M = Ti are characterized by trigonal bipyramidal (water molecules in front-side position) and octahedral coordination (for back-side position). Barrier heights for hydrolysis and condensation are substantially lower than those for silicon in keeping with experimental results.

Reductive splitting of cellulose in the ionic liquid 1-butyl-3-methylimidazolium chloride.

The depolymerization of cellulose is carried out in the ionic liquid 1-butyl-3-methylimidazolium chloride in the presence of hydrogen gas. First, the ketal 1,1-diethoxycyclohexane and cellobiose were used as model substrates. For the depolymerization of cellulose itself, the combination of a heterogeneous metal catalyst and a homogeneous ruthenium catalyst proved effective.

Rearrangements of [C(6)H(7)Si](+) cations. A radiochemical and quantum chemical study.

Nucleogenic cations were formed by beta-decay of phenylsilane tritiated at ortho- and para-positions of the benzene ring as well as at the silyl group and the products of their reactions with methyl tert-butyl ether were analyzed by radiochromatography. We found that the o-silatolyl cation was isomerized into the silabenzyl cation while the p-silatolyl cation was not. Furthermore, the silabenzyl cation was not converted into other isomers.

Role of structures with penta- and hexacoordinate silicon in the nucleophile-catalyzed hydrolysis of tetramethoxysilane.

The mechanism of the base catalyzed hydrolysis of tetramethoxysilane (TMOS), proposed earlier on the basis of experimental data, is assessed by theoretical methods, i.e. MP2 and B3LYP with 6-31G(d) and Dunning correlation-consistent basis sets.

Mechanism of the catalytic activity of nucleophiles in the stepwise hydrolysis and condensation reactions of tetramethoxysilane.

Active ingredients: A model for the simplest hydrolysis reaction is applied to all stages of stepwise hydrolysis and condensation taking place during a sol-gel process. The picture shows the molecular structures of the transition states of the ammonia- (left) and OH(-)-promoted (right) condensation reactions of two Si(OH)(4) molecules, including an additional water molecule.The previously proposed model of the catalytic activity of nucleophiles in the hydrolysis reaction of tetramethoxysilane is expanded to the subsequent stages of hydrolysis, that is, the stepwise hydrolysis of (MeO)(4-x)(OH)(x)Si (x=1-3) molecules, and to the condensation reaction of completely hydrolysed species.

Structure and vibrational spectra of Ti(IV) hydroxides and their clusters with expanded titanium coordination. DFT study.

Equilibrium structures of H(4-n)Ti(OH)n (n = 2-4) molecules and the Ti(OH)4 dimer and trimers were optimized at the B3LYP level of theory. Theoretical vibrational frequencies of TiO stretching modes obtained with several basis sets were compared with the existing experimental frequencies of these vibrations, and the 6-31+G(d) set was chosen for cluster calculations. Only one energy minimum was found for the [Ti(OH)4](2) dimer, but two isomers without symmetry elements stabilized by internal hydrogen bonds and two isomers, belonging to C(s) and C(i) point groups, with free OH groups were found as minima at the [Ti(OH)4](3) potential energy surface.

Dihydrogen and methane elimination from adducts formed by the interaction of carbenium and silylium cations with nucleophiles.

Stationary points for reactions R'R' 'HX(+) + YH --> [R'R' 'X-Y](+) + H(2) (I) and R'(CH(3))HX(+) + YH -->[R'HX-Y](+) + CH(4) (II) (R', R' ' = CH(3), H; X = C, Si; Y = CH(3)O, (CH(3))(2)N, and C(6)H(5)) are located and optimized by the B3LYP/aug-cc-pVDZ method. A similar mechanism was found to be operative for both types of reactions with X = C and X = Si. Formation of the intermediate (adduct) results in the transfer of electron density from the electron-rich bases to the X atoms and in the growth of a positive charge on a hydrogen atom attached to Y.

Vibrational spectra of trimethylsilanol. The problem of the assignment of the SiOH group frequencies.

The assignment of the SiOH group vibrations of trimethylsilanol, which is still controversial, is proposed. This assignment is based on theoretical B3LYP force field scaled using the constants of the (CH3)3Si group optimized to fit experimental vibrational frequencies of (CH3)3SiF and (CD3)3SiF molecules as well as the OH stretching scale factor from methanol. The ab initio force field defined in this way gives a good agreement of the theoretical vibrational frequencies of trimethylsilanol with the positions of IR and Raman bands observed in the gas phase.