Modeling of Complex Formation Equilibria and Proton and Ligand Exchange Reactions in Aqueous Solutions of Oxovanadium(IV) with L- and DL-Histidine

For the further development of the magnetic relaxation method, the STABLAB program was implemented, which makes it possible to calculate both thermodynamic equilibrium parameters and kinetic characteristics of the proton and ligand exchange reactions from the results of parallel measurements of the spin relaxation times T1 and T2, of solvent nuclei. With this program, the nuclear magnetic relaxation data on water protons were used to calculate the stability constants and proton and ligand exchange rates for the complexes formed in the oxovanadium(IV)-L-histidine (LH) and oxovanadium(IV)-DL-histidine systems at pH 0.5-10: VOLH, VO(LH)2, VOL, VOL2H, VOL2, VOL2H1, and (VO)2L2H-2. The structures of these complexes were determined based on the comparison of isotropic EPR parameters, stability constants, and molar proton relaxation coefficients. LH is coordinated in the equatorial plane of oxovanadium(IV) through the NH2 and COO- groups or through the imidazole nitrogen atom and the carboxy group; both of these coordination modes concurrently occur in the VO(LH)2 structure. The occurrence of two ligands exerts a synergistic effect on stabilization of the VO(LH)2, VOL2H, and VOL2 bis-complexes, which is explained by the effect of d-π bonding in the complexes with the trans arrangement of the imidazole nitrogen atom of one ligand and the COO- group of the other ligand in the equatorial plane. This d-π bonding is the main cause of some other unusual effects - the stereoselectivity in the formation of the VOL2 complex and the fast spontaneous proton exchange for VOL2H-1. In the proton exchange reactions, the enhanced kinetic activity of the LH2 form is attributed to the occurrence of the intraligand microequilibrium of the proton migration from the imidazole moiety to the carboxy group in interaction with VO2+ and to the fast interligand proton transfer in interaction with VOLH. A significant stereoeffect in the ligand exchange reactions was found for the first time: the rate constant of the exchange between VOL2 and L in solutions with L-histidine is 1.5 times the constant in solutions with DL-histidine. This is rationalized by the fact that the imidazole nitrogen atom in the VOL2 meso form efficiently protect the axial position from the attack of the entering ligand. The extremely high kinetic activity of the LH form in the ligand exchange with the oxovanadium(IV) complexes as compared to the complexes of other metal ions is attributed to a special mechanism that implies the formation of the hydrogen bond involving the protonated nitrogen atom of LH and the oxygen atom of V=O, as well as to a rather high nucleophilicity of the imidazole nitrogen atom of LH

Technique of Professionally-Applied Physical Training of Students of Building Specialties by Means of Orienteering

The problems of optimization of the educational process of physical culture in a higher educational institution are considered. Attention is paid to the development of professionally applied physical qualities of students in building specialties. The question of professional training with means of orienteering is being raised. The authors proceed from the assumption that the use of means and methods of orienteering in the classroom will lead to an improvement in the indexes of physical qualities, functional training and the working capacity of the civil engineer. It is noted that orienteering, as a sport, has a direct applied transfer of motor and associated skills. It is emphasized that the competences formed at students can find application in labor activity of the building specialist. The conclusion is made that the technique used leads to changes in the morphofunctional and motor components of physical readiness for labor activity. The results of a comparative analysis of the experimental and control groups on the indexes of physical development, functional state and physical qualities peculiar to builders are presented. The authors dwell on the development and approbation of the methodology used directly in the physical training classes for building students. It is proved that orienteering is an applied sport for the building specialties of the university, the means of which lead to the development of the physical qualities of a civil engineer

Hernia or hernia Defect? Experimental herniology Models in Laboratory Animals

Hernias of the anterior abdominal wall remain one of the most common surgery pathologies. There is no unified approach to modeling anterior abdominal wall hernias in the world scientific community. In order to systematize the available knowledge in this field and to contribute to the formation of a unified idea of how to create a hernia model in a laboratory animal, it seems logical to study the accumulated experience of researchers in the field of experimental herniology. We found out that hernia defects generally modeled on male laboratory rats. To understand the tissue reaction to the prosthetic material a fenestration was performed in the anterior abdominal wall (including peritoneum) except for the skin and subcutaneous fat. A replacement or prosthetic material tailored to the fenestration was sutured end-to-end into the abdominal wall. We chose laboratory rats because they are easy to take care of and cheaper than larger laboratory animals

ОЦЕНКА КОМБИНАЦИОННОЙ СПОСОБНОСТИ ПАРТЕНОКАРПИЧЕСКИХ ГИНОЦИЙНЫХ И МОНОЦИЙНЫХ ЛИНИЙ ОГУРЦА ПО ПРОДУКТИВНОСТИ КОРНИШОНОВ И ПРОДУКТИВНОСТИ СТАНДАРТНЫХ ПЛОДОВ

The results of a study of the genetic control and evaluation of combining ability for productivity of pickling cucumbers and standard fruits of 20 cucumber lines obtained after crossing 10 parthenocarpic gynoecious and 10 monoecious lines resistant to downy mildew are presented in the article. The cucumber lines with the high combining ability were identified. In the future, these lines will be used in breeding programs.Представлены результаты изучения генетического контроля и комбинационной способности 20 линий огурца по продуктивности корнишонов и продуктивности стандартных плодов при скрещивании 10 партенокарпических гиноцийных с 10 моноцийными устойчивыми к пероноспорозу линиями огурца. Выявлены линии с высокой комбинационной способностью для дальнейшего использования в селекционной программе

Modeling of Complex Formation Equilibria and Proton and Ligand Exchange Reactions in Aqueous Solutions of Oxovanadium(IV) with L- and DL-Histidine

For the further development of the magnetic relaxation method, the STABLAB program was implemented, which makes it possible to calculate both thermodynamic equilibrium parameters and kinetic characteristics of the proton and ligand exchange reactions from the results of parallel measurements of the spin relaxation times T1 and T2, of solvent nuclei. With this program, the nuclear magnetic relaxation data on water protons were used to calculate the stability constants and proton and ligand exchange rates for the complexes formed in the oxovanadium(IV)-L-histidine (LH) and oxovanadium(IV)-DL-histidine systems at pH 0.5-10: VOLH, VO(LH)2, VOL, VOL2H, VOL2, VOL2H1, and (VO)2L2H-2. The structures of these complexes were determined based on the comparison of isotropic EPR parameters, stability constants, and molar proton relaxation coefficients. LH is coordinated in the equatorial plane of oxovanadium(IV) through the NH2 and COO- groups or through the imidazole nitrogen atom and the carboxy group; both of these coordination modes concurrently occur in the VO(LH)2 structure. The occurrence of two ligands exerts a synergistic effect on stabilization of the VO(LH)2, VOL2H, and VOL2 bis-complexes, which is explained by the effect of d-π bonding in the complexes with the trans arrangement of the imidazole nitrogen atom of one ligand and the COO- group of the other ligand in the equatorial plane. This d-π bonding is the main cause of some other unusual effects - the stereoselectivity in the formation of the VOL2 complex and the fast spontaneous proton exchange for VOL2H-1. In the proton exchange reactions, the enhanced kinetic activity of the LH2 form is attributed to the occurrence of the intraligand microequilibrium of the proton migration from the imidazole moiety to the carboxy group in interaction with VO2+ and to the fast interligand proton transfer in interaction with VOLH. A significant stereoeffect in the ligand exchange reactions was found for the first time: the rate constant of the exchange between VOL2 and L in solutions with L-histidine is 1.5 times the constant in solutions with DL-histidine. This is rationalized by the fact that the imidazole nitrogen atom in the VOL2 meso form efficiently protect the axial position from the attack of the entering ligand. The extremely high kinetic activity of the LH form in the ligand exchange with the oxovanadium(IV) complexes as compared to the complexes of other metal ions is attributed to a special mechanism that implies the formation of the hydrogen bond involving the protonated nitrogen atom of LH and the oxygen atom of V=O, as well as to a rather high nucleophilicity of the imidazole nitrogen atom of LH

Modeling of Complex Formation Equilibria and Proton and Ligand Exchange Reactions in Aqueous Solutions of Oxovanadium(IV) with L- and DL-Histidine

For the further development of the magnetic relaxation method, the STABLAB program was implemented, which makes it possible to calculate both thermodynamic equilibrium parameters and kinetic characteristics of the proton and ligand exchange reactions from the results of parallel measurements of the spin relaxation times T1 and T2, of solvent nuclei. With this program, the nuclear magnetic relaxation data on water protons were used to calculate the stability constants and proton and ligand exchange rates for the complexes formed in the oxovanadium(IV)-L-histidine (LH) and oxovanadium(IV)-DL-histidine systems at pH 0.5-10: VOLH, VO(LH)2, VOL, VOL2H, VOL2, VOL2H1, and (VO)2L2H-2. The structures of these complexes were determined based on the comparison of isotropic EPR parameters, stability constants, and molar proton relaxation coefficients. LH is coordinated in the equatorial plane of oxovanadium(IV) through the NH2 and COO- groups or through the imidazole nitrogen atom and the carboxy group; both of these coordination modes concurrently occur in the VO(LH)2 structure. The occurrence of two ligands exerts a synergistic effect on stabilization of the VO(LH)2, VOL2H, and VOL2 bis-complexes, which is explained by the effect of d-π bonding in the complexes with the trans arrangement of the imidazole nitrogen atom of one ligand and the COO- group of the other ligand in the equatorial plane. This d-π bonding is the main cause of some other unusual effects - the stereoselectivity in the formation of the VOL2 complex and the fast spontaneous proton exchange for VOL2H-1. In the proton exchange reactions, the enhanced kinetic activity of the LH2 form is attributed to the occurrence of the intraligand microequilibrium of the proton migration from the imidazole moiety to the carboxy group in interaction with VO2+ and to the fast interligand proton transfer in interaction with VOLH. A significant stereoeffect in the ligand exchange reactions was found for the first time: the rate constant of the exchange between VOL2 and L in solutions with L-histidine is 1.5 times the constant in solutions with DL-histidine. This is rationalized by the fact that the imidazole nitrogen atom in the VOL2 meso form efficiently protect the axial position from the attack of the entering ligand. The extremely high kinetic activity of the LH form in the ligand exchange with the oxovanadium(IV) complexes as compared to the complexes of other metal ions is attributed to a special mechanism that implies the formation of the hydrogen bond involving the protonated nitrogen atom of LH and the oxygen atom of V=O, as well as to a rather high nucleophilicity of the imidazole nitrogen atom of LH

EVALUATION OF COMBINING ABILITY OF PARTHENOCARPIC GENOECIOUS AND MONOECIOUS LINES FOR PRODUCTIVITY OF PICKLING CUCUMBERS AND STANDARD FRUITS

The results of a study of the genetic control and evaluation of combining ability for productivity of pickling cucumbers and standard fruits of 20 cucumber lines obtained after crossing 10 parthenocarpic gynoecious and 10 monoecious lines resistant to downy mildew are presented in the article. The cucumber lines with the high combining ability were identified. In the future, these lines will be used in breeding programs

Effect of cultivation factors on embryogenesis in isolated microspore culture of carrot (Daucus carota L.)

Using doubled haploid technologies inbreeding can significantly reduce the time to obtain homozygous parental lines required for the production of F1-hybrid of vegetable crops. This study aims to investigate the influence of factors on the efficiency of carrot embryogenesis in isolated microspore culture to optimise the elements of protocol for producing doubled haploids. Microspores were isolated from inflorescences of 21 genotypes and incubated in NLN13 medium supplemented with 0.1 mg·dm-3 2,4-dichlorophenoxyacetic acids, 0.1 mg·dm-3 1-naphthyl acetic acids, 130 g·dm-3 sucrose, and 400 mg·dm-3 casein hydrolysate and its modifications. Embryoids and their groups were formed after 2–6 months, in some cases after 12 months of cultivation. Depending on the variant, the embryogenesis efficiency averaged from 0 to 4.9 embryoids or groups of embryoids per Petri dish (10 cm3). Embryoids within the group were formed from different microspores. No significant effects of inflorescence position on the plant (branching order), sucrose, and casein hydrolysate concentration in the medium were observed. Significant advantages (p ≥ 0.05) for some genotypes were shown: 1) microspore suspension density 4·104 cells·cm-3 (5.0 embryoids per Petri dish were formed at a microspore suspension density of 4·104 cells·cm-3, 0.0 embryoids per Petri dish at a density of 8·104 cells·cm-3); 2) cultivating microspores of tetrad and early mononuclear stage (4.9 ±3.1 embryoids per Petri dish were obtained by culturing tetrads and early mononuclear microspores, while 0.6 ±0.7 embryoids per Petri dish were obtained by culturing of later developmental stages); 3) high-temperature treatment duration of five days (4.9 ±2.1 embryoids per Petri dish were obtained after five days of high-temperature treatment, 2.7 ±2.6 embryoids per Petri dish formed after two days of high-temperature treatment; 9.8 ±4.7, 10.1 ±6.1, 0.0 ±0.0 embryoids per Petri dish formed after two, five and eight days of high-temperature treatment respectively); 4) adding colchicine 0.5 mg·dm-3 to the nutrient medium for two days of high-temperature treatment, followed by medium replacement (3.3 ±2.6 embryoids per Petri dish were obtained by using a nutrient medium with colchicine, while 1.7 ±1.5 embryoids per Petri dish were obtained by culturing in the reference variant)