EVALUATION OF THE ECOLOGICAL SITUATION OF RURAL GEOSYSTEMS OF NORTHEN BUKOVINA

The article presents the theoretical and methodological foundations of landscape- geochemical analysis and an evaluation of Northern Bukovina rural geosystems. Based on the results of field and chemical analysis, calculations of environmental and geochemical indicators, characterizations of the degree of geochemical pollution load and the intensity of natural components, an environmental assessment of the geosystems of the study area is mad

Half-sandwich silane complexes of ruthenium and iron : synthesis, structure and application to catalysis

The present thesis describes syntheses, structural studies, and catalytic reactivity of new non-classical silane complexes of ruthenium and iron. The ruthenium complexes CpRu(PPri3)CI(T]2-HSiR3) (1) (SiR3 = SiCh (a), SiClzMe (b), SiCIMe2 (c), SiH2Ph (d), SiMe2Ph (e» were prepared by reactions of the new unsaturated complex CpRu(PPri3)CI with silanes. According to NMR studies and X-ray analyses, the complexes la-c exhibit unusual simultaneous Si··· H and Si··· CI-Ru interactions. The complex CpRu(PPri3)CI was also used for the preparation of the first examples of late transition metal agostic silylamido complexes CpRu(PPri3)(N(T]2-HSiMe2)R) (2) (R= Ar or But), which were characterized by NMR spectroscopy. The iron complexes CpFe(PMePri2)H2(SiR3) (3) (SiR3 = SiCh (a), SiClzMe (b), SiCIMe2 (c), SiH2Ph (d), SiMe2Ph (e» were synthesized by the reaction of the new borohydride iron complex CpFe(PMePri2)(B~) with silanes in the presence NEt3. The complexes 3 exhibit unprecedented two simultaneous and equivalent Si··· H interactions, which was confirmed by X-ray analyses and DFT calculations. A series of cationic ruthenium complexes [CpRu(PR3)(CH3CN)(112-HSiR'3)]BAF (PR3 = PPri 3 (4), PPh3 (5); SiR'3 = SiCh (a), SiClzMe (b), SiClMe2 (c), SiH2Ph (d), SiMe2Ph (e» was obtained by substitution of one of the labile acetonitrile ligands in [CpRu(PR3)(CH3CNh]BAF with sHanes. Analogous complexes [TpRu(PR3)(CH3CN)(T]2 -HSiR' 3)]BAF (5) were obtained by the reaction of TpRu(PR3)(CH3CN)CI with LiBAF in the presence of silanes. The complexes 4-5 were characterized by NMR spectroscopy, and the observed coupling constants J(Si-H) allowed us to estimate the extent of Si-H bond activation in these compounds. The catalytic activity in hydrosilylation reactions of all of the above complexes was examined. The most promising results were achieved with the cationic ruthenium precatalyst [CpRu(PPri3)(CH3CN)2t (6). Complex 6 shows good to excellent catalytic activity in the hydrosilylation of carbonyls, dehydrogenative coupling of silanes with alcohols, amines, acids, and reduction of acid chlorides. We also discovered very selective reduction of nitriles and pyridines into the corresponding N-silyl imines and l,4-dihydropyridines, respectively, at room temperature with the possibility of catalyst recycling. These chemoselective catalytic methods have no analogues in the literature. The reactions were proposed to proceed via an ionic mechanism with intermediate formation of the silane a-complexes 4

Multi-Criteriality as a Factor of Project Risk

The article considers the project risk as a potential danger regarding the achievement of the project’s objectives in the objective impossibility of operating full and reliable information about the status of the environment. The methodical bases of planning of the project-oriented development of enterprise are elaborated taking into view various conditions. The procedure includes the following successive stages: determining the vision and objectives of the enterprise development; analyzing the business processes and determining the directions and risks of development; evaluating the potential and conditions of development to ensure further changes; forming the set of alternative business-projects of the enterprise development; forming the optimal program as to the risk level. It is defined that development of industrial enterprise envisages implementation of project actions for active change of business environment. The instrument of such actions is the development program, which includes groups of projects. The economic-mathematical model of formation of an optimum program of development of enterprise in accordance with the chosen goal and vision of development is elaborated

Activation of Water, Ammonia, and Other Small Molecules by PC_carbeneP Nickel Pincer Complexes

Nickel complexes of a PC_carbeneP pincer ligand framework are described. Dehydrobromination of the precursor (PC_sp³P)­NiBr in the presence of a donor (PPh₃ or NC^tBu) leads to the title complexes, which feature a rare nickel–carbene linkage as the pincer ligand anchor point. This strongly donating, nucleophilic carbene center engages in a variety of E–H bond activations (E = H, C, N, O), some of which are reversible. This represents a new mode of bond activation by ligand cooperativity in nickel pincer complexes

Dimerization of Ethylene by Nickel Phosphino–Borate Complexes

Trifluoroborate-functionalized phosphine ligands react with a variety of nickel­(II) precursors to cleanly yield a number of κ²(P,F)-bound nickel complexes, which were characterized crystallographically. In comparison to related palladium complexes, ancillary ligands in the nickel complexes were observed to be generally more weakly bound, and the trifluoroborate ligands were more easily displaced by coordinating solvents that did not cause a similar displacement in a related palladium system. Such weaker ligand coordination resulted in a much faster dimerization of ethylene. Experiments conducted under constant ethylene pressure saw the suppression of the isomerization of 1-butene observed in related palladium complexes; higher oligomers were also generated under such conditions

Biological tissues high-frequency electric welding in biliodigestive anastomoses formation in the experimental and clinical conditions

The aim of the study – to improve the treatment results of patients with main bile duct disturbances, using the modern method of tissues high-frequency electric welding (HFEW) for the hepaticojejunic anastomoses formation. Material and methods. The formation of 15 models of termino-lateral hepaticojejunic anastomoses were performed experimentally. The modelings were done using “bioimitators” in the form of both hepaticocholedochus and small intestine fragments, removed during pancreatoduodenal resections. The HFEW method was used in 14 patients with the main biliary outflow disturbances for hepaticojejunic anastomoses formation: 6 patients were operated as the result of a periampular zone malignant tumor complicated by mechanical jaundice, 2 patients with chronic pancreatitis presented tubular stenosis of the distal part of the common bile duct, 6 patients presented scars and bile ducts iatrogenic lesions. The control group consisted of 60 patients in whom hepaticojejunic anastomoses was formed traditionally. Results. Hepaticojejunic anastomoses formed by biological tissues radio-frequency (RF)-welding method were passable, completely sealed and had sufficient strength (706.9±70.0 H2O mm). The primary narrowing of anastomoses lumen, formed by the HFEW method, was smaller (13.6±2.1%), compared to the same in the anastomoses formed by the suture method (49.1±3.4%). It was proved histologically that a coagulation suture was formed during electrowelding, and tissue joining was due to changes in the protein conformation of the intercellular substance and the destructed cells. The comparative analysis of clinical and laboratory data in patients of both main and control groups, provided during the postoperative period, revealed better results in the main group patients compared to the control group – the duration of anastomoses formation in case of RF-welding was averagely by 19 minutes (43.2%) shorter comparing to the duration in case of ligature use; the total bilirubin level throughout the postoperative period decreased quicker in the main group (40.4±6.2 μmol/l) comparing to the decrease in the control group (55.0±8.0 μmol/l); one could register both AlAT and AsAT levels quicker. Ultrasound investigation and Magnetic Resonance Cholangiopancreatography, performed at different times of the postoperative period, also proved HFEW anastomoses good patency and tightness. Conclusions. HFEW method for soft biological tissues in clinical practice allows to create reliable biodigestive anastomoses, especially in conditions of inflammation. One could see decrease in early postoperative complications frequency and both bilirubin and transaminases levels faster normalization while using HFEW methods, which indicates liver function rapid recovery