Characterization and design of hydrogen bonding interactions in oxygen reduction by engineered myoglobins

Proteins participate in nearly every function of living cells, and an estimated 50% are associated with a metal ion or cofactor. Most, if not all, of the fundamental chemical processes necessary for life, including photosynthesis and respiration, are facilitated by one or more metalloenzymes or metalloproteins. Metal-nucleic acid interactions are also clinically important in cancer and infection treatment, and are useful in industrial purposes. The relationship between macromolecule and metal can almost be viewed as symbiotic – metals often function at extreme limits when free in solution, with minimal ligands; on the other had, amino and nucleic acid polymers have limited functional capabilities. By capturing and precisely holding metal ions, biomolecules tame their reactivities by tuning their electronic and geometric – and therefore functional – properties, allowing the metal and protein together to perform precise chemical functions. However, despite decades of research, the intricate details of how this precision is imparted, in each case and more generally, are not entirely understood. In particular, the roles of long-range (beyond 1-2 bonds), non-covalent interactions are understood to be important; however, exactly how they impart function, is difficult to disentangle, due to the delicate balance resulting from evolution. Moreover, many of these systems, such as the oxidases and photosystems responsible for respiration and photosynthesis, respectively, are large, difficult to purify, and contain multiple cofactors that complicate investigations of the active site chemistry. Therefore, in the Lu lab, we have been pioneers of the "biosynthetic" modeling approach, in which the active sites of complex enzymes are structurally reconstructed in small, experimentally tractable proteins. In this vein, the active site of heme-copper oxidases (HCOs) – a bimetallic heme-copper center known as CuB – was previously structurally modeled in sperm whale myoglobin, by introducing two additional histidine residues, giving a protein called CuBMb. Further structural modeling of this protein to include additional structural features, such as a tyrosine residue, brought about not only partial HCO-like oxygen reduction activity, but an unexpected observation – the Cu ion was found to not be necessary for imparting this function, nor did it seem to improve it, in the designed protein. On the other hand the presence and positioning of the tyrosine had a dramatic effect on this activity. This thesis describes efforts to first understand the reaction of these CuBMbs with oxygen. It is found that the extended hydrogen bonding network, stabilized by the introduced residues and consisting of water molecules, is critical for imparting oxygen reduction activity to an oxygen binding protein. Based on this observation, further designs are pursued to improve this hydrogen-bonding network, in an effort to improve activity. It is found that incorporation of a glutamate within hydrogen bonding distance of one of the water molecules composing the extended hydrogen bonding network improves the function of the enzyme by eliminating the ROS release. Moreover, spectroscopic and crystallographic evidence support that this improvement is due to enhanced hydrogen bonding and protonation to the oxygen intermediate. This design demonstrates the critical importance of long-range interactions in enzymes, and should inspire enzyme engineers to pursue incorporation of these types of features. In addition to these studies, this thesis also reports the computational design of a novel heterobimetallic heme-Fe4S4 site, and progress in obtaining the first crystal structure of a metal mediated catalytic DNA construct

Changes in the Efficiency of Photovoltaic Energy Conversion in Temperature Range with Extreme Limits

The efficiency of the photovoltaic energy conversion depends on the temperature significantly. We monitored the behavior of I-V characteristics of the PV cell based on monocrystalline silicon in temperature range with extreme limits from-170 °C to +100 °C. We have not yet found a similar measurement in this temperature interval. The temperature of PV modules without radiation concentration can reach values of-100 °C to +100 °C on the Earth\u27s surface. The temperature range may be few wider in space. Changes of I-V characteristics and P-V characteristics are discussed in terms of the theory of solids. The open-circuit voltage dependence is approximately linear over a wide temperature range, but saturation occurs at temperatures around-150 °C, which is also explained in accordance with the theory of semiconductors. The decrease in energy conversion efficiency with increasing temperature has a value of about 0.5%/°C throughout the whole temperature range possible on the Earth\u27s surface. If there are large changes in the temperature of the PV modules during operation of the PV system, the electrical voltage of the PV modules will also change considerably. In space applications, these fluctuations may be greater. This must be taken into account when designing PV systems (especially for deep space missions). For example, electronic inverters are sensitive to overvoltage or undervoltage

Features of the economical yield formation of apple plants under non-root nutrition in the Southern Russia organic plantings

In this work are determined the prospects of application new complex fertilizer chelate “Naliv” for apple plants non-root nutrition in connection with optimization of economic yield formation in the Southern Russia organic plantations. The field experiment was carried out in the organic apple tree plantations of the educational farm "Kuban" of the KubSAU, planted in 2002. The experimental field soil is leached chernozem. Trees foliar dressing was carried out with organic fertilizer 40-45 days before harvest. Control variant was trees treatment with water. The accumulation of glucose and fructose, associated with a significant (1.4 times) increase in their average weight, activate in ripening fruits under fertilizer application as a late-summer foliar dressing. Equally, the economic yield increases by 14% compared to control value. The fertilizer application accelerates the generative apple bud dormancy beginning and, accordingly, dormancy ending. An increase in the abscisic acid content in generative buds in late autumn, initiated by the fertilizer action, plays a certain role in achieving this effect. Equally, the plants resistance to low temperatures of the spring increases. Thus, favorable conditions are created to improve the commercial quality of fruits and optimize fruiting in adjacent years under fertilizers application in organic apple plantations

Features of the economical yield formation of apple plants under non-root nutrition in the Southern Russia organic plantings

In this work are determined the prospects of application new complex fertilizer chelate “Naliv” for apple plants non-root nutrition in connection with optimization of economic yield formation in the Southern Russia organic plantations. The field experiment was carried out in the organic apple tree plantations of the educational farm "Kuban" of the KubSAU, planted in 2002. The experimental field soil is leached chernozem. Trees foliar dressing was carried out with organic fertilizer 40-45 days before harvest. Control variant was trees treatment with water. The accumulation of glucose and fructose, associated with a significant (1.4 times) increase in their average weight, activate in ripening fruits under fertilizer application as a late-summer foliar dressing. Equally, the economic yield increases by 14% compared to control value. The fertilizer application accelerates the generative apple bud dormancy beginning and, accordingly, dormancy ending. An increase in the abscisic acid content in generative buds in late autumn, initiated by the fertilizer action, plays a certain role in achieving this effect. Equally, the plants resistance to low temperatures of the spring increases. Thus, favorable conditions are created to improve the commercial quality of fruits and optimize fruiting in adjacent years under fertilizers application in organic apple plantations.</jats:p

EVALUATION OF MOTOR WHEEL MOVEMENT IN DIFFICULT OPERATING CONDITIONS

The operational properties of the automotive system determine the performance of the automotive system of its production functions (properties that determine the average speed, fuel consumption, traffic safety, the ability to drive on different roads and off them, and the like). The main performance properties of the automotive system are defined by the main manufacturers as dynamics, fuel economy, controllability, stability, smoothness, passability, capacity, strength, reliability, durability, suitability of the car for maintenance and repair, suitability for loading and unloading. The main characteristic of the automotive system in terms of trouble-free operation is its dynamism, which is characterized by maximum speeds of rectilinear traffic in various road conditions, as well as the ability to quickly change the speed and accident-free encounter with an obstacle. The dynamics of the automotive system includes traction and brake dynamics. Traction dynamics is determined by the maximum speeds and accelerations, and braking dynamics – the ability to quickly reduce the speed. Fuel efficiency of the automotive system is characterized by fuel consumption associated with the performance of production functions. Fuel costs make up a significant part of the cost of transportation. Therefore, the lower the fuel consumption, the cheaper the operation of the car. The controllability of the car system is characterized by its ability to change or maintain driving parameters as a result of the driver’s influence on the steering. The safety of the car largely depends on the handling. In the article the dynamics of the car wheel movement of the car system and the interaction of the wheel drive of the truck with the obstacle of the support surface is considered, which allows the process of moving the truck to subject the rolling process directly through the resistance of the obstacle surface. To this end, a physico-mathematical model of the movement of a car wheel through an obstacle of the supporting surface was proposed, which also corresponds to the movement of the wheel drive of a truck. In developing a mathematical model, we used a theorem that describes the occurrence of a kinetic moment during the impact of a car wheel in the obstacle of the support surface. Calculations and graphical dependencies were performed in Excel. The results of these calculations showed the area of most efficient rolling of the wheel drive by rotational motion. Keywords: automobile wheel, obstacle, bearing surface, car, resistance, movement, rolling.</jats:p

PECULIARITIES OF TRANSFORMATION OF THE CONCEPT OF THE INFANTRY COMBAT MACHINE IN MODERN CONDITIONS

The analysis of concepts and technologies of improvement and transformation of infantry fighting vehicles at the present stage of development is carried out. The problem of inconsistency of combat capabilities of modern infantry fighting vehicles with their original purpose, the so-called problem of passivity, is covered. A detailed analysis of the characteristics of modern and promising infantry fighting vehicles and armored personnel carriers is presented in order to assess their combat and technical characteristics. According to the results of the analysis, it is indicated that none of the considered samples of combat armored vehicles is fully applied to autonomous or joint actions along with tanks due to insufficient level of protection, limited capabilities or complete passivity of the landing party. Particular attention is paid to the study of ways of constructive transformation of the infantry fighting vehicle on the platform of the T-64 tank of domestic production. Compromise approaches to the layout of modern infantry fighting vehicles with an optimal combination of fire capabilities, security, mobility and improving the maintainability and operational qualities of the combat vehicle are proposed. A well-founded analysis of the existing models of heavy infantry fighting vehicles in service in the armies of different countries has been carried out. Tactical and technical requirements for a promising heavy infantry fighting vehicle of domestic production based on the T-64 tank are substantiated. Conceptual directions of transformation of the infantry fighting vehicle in modern conditions of conducting military operations are defined. Ways of modernization of samples of armored combat vehicles on the basis of developments of the Kharkiv design bureau on mechanical engineering named after A.A. Morozov with the introduction of the Russian military-industrial complex. Keywords: infantry fighting vehicle, combat capabilities, security, combat effectiveness, enemy, tank, concept, design, transformation.</jats:p