The Synthesis,Physicochemical Properties,and Thermo-Oxidative Stability of Esters of a Tricarboxylic Acid of the Adamantane Series

A series of triesters of 3,5-bis(carboxymethyl)-1-adamantanecarboxylic acid have been synthesized and their physicochemical and thermo-oxidative properties have been studied. The properties of the obtained triesters have been compared to those of trioctyl trimellitate, which is used as a plasticizer and a component of various lubricating materials.     

Measuring the heat-transfer coefficient of nanofluid based on copper oxide in a cylindrical channel

The heat-transfer coefficient of nanofluid during its flow in a cylindrical channel is studied experimentally. The studied nanofluid was prepared based on distilled water and CuO nanoparticles. Nanoparticle concentration varied in the range from 0.25 to 2% in the volume. The nanofluid was stabilized using a xanthane gum biopolymer the mass concentration of which did not exceed 0.03%. Considerable intensification of heat transfer was found. The nanofluid appeared to be Newtonian when particle concentrations exceeded 0.25%. Estimates for rheological parameters of the nanofluid and thermal conductivity coefficient have been obtained.     

Experience in using the acoustic emission method when constructing hydraulic tunnels

Conclusions  1. The curve of AE intensity in a hole with observance of certain recording conditions adequately reflects the structure and stage of regions being deformed in the vicinity of workings. 2. Both recording parameters and geometric characteristics of the section of observations (form of the contour of the working, presence of interfaces, etc.) affect the value of the recorded AE intensity. 3. The results of using the AE method at the site of the Zhinvala hydrostation and Dnestr pumped-storage station showed its high effectiveness for determining the structure and state of the rock mass as part of the set of static and dynamic methods of investigation. Translated from Gidrotekhnicheskoe Stroitel’stvo, No. 1, pp. 17–19, January, 1998.     

Optimizing Operation of Diesel Fuel Hydrotreating Plants

Two two-unit diesel fuel hydrotreating plants — L-24-6 (started up in 1964) and LCh-24-7 (started up in 1970) were planned to produce 900,000 and 1,200,000 tons/year using cold separation and a working pressure of 3–3.5 MPa in the system. In 1976-1979, hot separation, developed by refinery specialists, was introduced for the first time in plants of this type.     

Influence of the physical properties of the material of nanoparticles on their diffusion in rarefied gases

The influence of the physical properties of nanoparticle materials and the parameters of the molecule-particle-interaction potential on the diffusion of nanoparticles has been studied on the basis of kinetic theory. It has been established that unlike Brownian particles, the diffusion of fairly small nanoparticles is substantially dependent on their material. This effect becomes stronger with growth in the carrier-gas temperature. In all cases the use of the well-known Cunningham-Milliken-Davies correlation brings about considerable errors in determining the diffusion coefficient of nanoparticles. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 3, pp. 496–500, May–June, 2008.     

Measuring of critical density of heat flow during boiling of nanoliquids on a cylindrical heater

Saturated boiling of nanoliquids on a cylindrical heater is experimentally studied. The studied nanoliquids were prepared using distilled water and Fe3O4 iron oxide or diamond nanoparticles. The volume concentration of the nanoparticles was changed from 0.25 to 1%. It has been measured that the critical density of heat flow in nanoliquids is far higher than in water. Moreover, it depends on size of nanoparticles.     

Nanoparticle velocity relaxation in a condensed carrying medium

The interaction of a nanoparticle occurring in a carrying condensed medium with fluctuations of the medium momentum caused by the particle motion have been studied. The space-time velocity correlation functions of the nanoparticle and surrounding molecules were determined by the molecular dynamics method. These functions exhibit one or two maxima, depending on the system parameters. The first maximum is related to an acoustic wave propagating in the medium, and the second, to multiple collisions between the nanoparticle and nearest neighbor molecules. It is established that collective effects significantly influence both the velocity autocorrelation function and the diffusion coefficient of the nanoparticle.     

Aggregation gatekeepers modulate protein homeostasis of aggregating sequences and affect bacterial fitness

The most common mechanism by which proteins aggregate consists in the assembly of short hydrophobic primary sequence segments into extended β-structured agglomerates. A significant enrichment of charged residues is observed at the flank of these aggregation-prone sequence segments, suggesting selective pressure against aggregation. These so-called aggregation gatekeepers act by increasing the intrinsic solubility of aggregating sequences in vitro, but it has been suggested that they could also facilitate chaperone interactions. Here, we address whether aggregation gatekeepers affect bacterial fitness. In Escherichia coli MC4100 we overexpressed GFP fusions with an aggregation-prone segment of σ32 (further termed σ32β) flanked by gatekeeper and non-gatekeeper residues and measured pairwise competitive growth. We found that the identity of flanking residues had significant effect on bacterial growth. Overexpression of σ32β flanked by its natural gatekeepers displayed the greatest competitive fitness, followed by other combinations of gatekeepers, while absence of gatekeepers strongly affects bacterial fitness. Further analysis showed the diversity of effects of gatekeepers on the proteostasis of σ32β including synthesis and degradation rates, in vivo aggregation propensity and chaperone response. Our results suggest that gatekeeper residues affect bacterial fitness not only by modulating the intrinsic aggregation propensity of proteins but also by the manner in which they affect the processing of σ32β-GFP by the protein quality control machinery of the cell. In view of these observations, we hypothesize that variation at gatekeeper positions offers a flexible selective strategy to modulate the proteostatic regulation of proteins to the match intrinsic aggregation propensities of proteins with required expression levels.