Differential Response of Leafminer Flies Liriomyza trifolii (Burgess) and Liriomyza sativae (Blanchard) to Rapid Cold Hardening

Rapid cold hardening (RCH) is a rapid and critical adaption of insects to sudden temperature changes but is often overlooked or underestimated as a component of survival. Thus, interspecific comparisons of RCH are needed to predict how phenotypes will adapt to temperature variability. RCH not only enhances cold survival but also protects against non-lethal cold injury by preserving essential functions such as locomotion, reproduction, and energy balance. This study investigated the difference in basal cold tolerance and RCH capacity of L. trifolii and L. sativae. In both species, the cold tolerance of pupae was significantly enhanced after short-term exposure to moderately cold temperatures. The effect of RCH last for 4 h in L. sativae but only 2 h in L. trifolii. Interestingly, L. trifolii adults had a RCH response but L. sativae adults failed to acclimate. Short-term acclimation also lowered the supercooling point significantly in the pupae of both species. Based on these results, we propose a hypothesis that these differences will eventually affect their competition in the context of climate change. This study also provides the basis for future metabolomic and transcriptomic studies that may ultimately uncover the underlying mechanisms of RCH and interspecific competition between L. trifolii and L. sativae.

Measuring diameter of water jets affecting propeller blade surface under cavitation wear

The article analyses the structure of cavitated areas of the ship propeller blades made from aluminum bronzes with different composition. The most informative zones of cavitation wear are the cold-hardening zone and the peripheral one that help estimate the mechanical parameters causing the cavities to collapse. The dents formed on the metal surface in the process of hydrodynamic cavitation wear have spherical parts on their bottoms, in which it is possible to inscribe a circle of a definite diameter. There were conducted the experiments on forcing the ball indentors into the surface of different metal alloys. The first run of the experiments includes forcing of a steel ball with a diameter of 1.588 mm into the surface of 33 alloys with different hardness under the loads of 1 470, 980 and 588 N. The impression diameters were measured using Brinell magnifying glass. There has been found the power dependence between deformation of dents on the metals tested under hydrodynamic cavitation and hardness of the materials, which is similar to the dependence of deformation after forcing the ball indentors into the alloys of different hardness. The second run of the experiments included modeling the cold-hardening zone of the cavitation wear area by repeated forcing the ball indentors with the diameters of 1.588, 2.5, 3.175 and 5.0 mm into the bronze BrAZhNMts9-4-4-1 plates with area of 100 × 50 × 20 mm. Forcing was made into the side 100 × 50 mm previously ground and polished. The equal strain rate in impressions of different diameters was observed during forcing. A direct proportional relationship was obtained between the arithmetic mean deviation of the surface profile and the indenter diameter. The arithmetical mean deviation of the assessed profile of the side plotted against the ball indentor yields a direct proportional relationship. Using the dependence for the case of cavitation attack on the propeller blades helps to infer that the diameter of water jets striking against the propeller blade surface with diameter of 3 700 mm makes about 10 mm. The obtained value allows to choose reasonably the experimental equipment and the parameters of testing the ship propeller materials for cavitation wear.

Plasticity in thermal hardening of the invasive Asian house gecko

The Asian house gecko (Hemidactylus frenatus) is a tropical invasive species that has established and spread throughout several temperate regions around the world. In some invasive species, rapid thermal acclimation (thermal hardening) may contribute to their success in occupying a wide range of climates. In this study, we investigated whether invasive house geckos from southeastern Australia show differing thermal hardening responses than individuals from the native range in Thailand. In the laboratory, we measured the basal heat tolerance (CTmax) of the geckos and their heat hardening response after being subjected to the second thermal stress after 1, 3, 5, 7, 9, or 11 hours. When geckos had recovered, we measured their basal cold tolerance (CTmin) and cold hardening response over the same time intervals. We then explored whether hardening responses differed between populations or among time intervals. We found that basal heat tolerances did not differ between populations, but geckos from Australia had lower cold tolerance than geckos from Thailand. The magnitude of the heat hardening was similar between populations, but the introduced geckos had a higher magnitude of cold hardening. The native geckos could maximize their cold tolerance capacity for only 0.6 °C, comparing to 0.9 °C of the introduced geckos. Also, geckos from Australia exhibited faster responses to thermal stress than did geckos from Thailand. Maximum thermal tolerances as a result of hardening responses peaked within three hours after thermal stress in Australian geckos (adjusted means = 44.0 °C for CTmax and 9.9 °C for CTmin) and at five hours after thermal stress in Thai geckos (adjusted means = 44.2 °C and 10.2 °C, respectively). The plasticity in the thermal hardening of the invasive gecko should enable it to survive rapid temperature fluctuations, especially cold snap, that occasionally occur in temperate regions.

Analysis of the mixing efficiency of the components of the iron-phosphate mixture in the dry state

The results of researches of influence of time of mixing of initial components in a dry condition on degree of assimilation of iron-containing component of forming and core iron-phosphate cold-hardening mixes are presented. The percentage of assimilation of the dispersed iron-containing component after each minute of mixing in laboratory runners with a total mixing time of 15 minutes was determined experimentally. Using the original method of particle separation, under the microscope were separated scale particles that were not assimilated (not distributed on the surface of the sand), and weighed them. The dependences of the degree of assimilation of the metal component of the iron-phosphate mixture on the mixing time at different initial contents are obtained. It is shown that the highest degree of absorption of the iron-containing component of iron-phosphate mixtures is achieved by mixing the components of the mixture for the first four to five minutes. Then this figure begins to decrease as the grains begin to collapse under the action of the rolls of the runners, and the forces of electrostatic interaction between the surfaces of the grains and the dispersion medium are reduced compared to the forces of mutual gravity between the dispersed particles of iron-containing component of the mixture. Based on the analysis of theoretical positions and the results of experimental studies, the assumption is made about the possibility of adjusting the conditions and parameters of solidification of phosphate binder systems, in particular using iron-containing filler of a certain dispersion and mixing the components in the dry state for some time. It is known that for mixing the components and assimilation of the required part of the iron-containing component of the mixture uses a significant amount of energy (depending on the type of unit used). To reduce the energy consumption of this process, the urgent task is to determine the degree of assimilation of the iron-containing component of phosphate cold-hardening mixtures in their manufacture by mixing the components in the dry state. Keywords: iron-phosphate cold-hardening mixture, mixing in the dry state, interaction, adhesion, experiment, research, dependence

The content of secondary metabolites in triticale seedlings of different genotypes under cold hardening conditions

The mechanisms of low-temperature adaptation of triticale (w Triticosecale Wittm.), an intergeneric hybrid that combining high productivity and frost resistance, are not well understood. In particular, the question remains open about the contribution of secondary metabolites to the functioning of its antioxidant system during the formation of frost resistance. The dynamics of the total content of phenolic compounds, flavonoids, and separately the amount of anthocyanins under cold hardening conditions (6 days at temperature of 2—4 °C) of seedlings of varieties with different frost resistance: Buket and Raritet (winter, high-frost-resistant), and Alexandra (winter, notfrostresistant) and Pidzymok kharkivskiy (facultative, less resistant) were studied. The content of phenolic compounds in non-hardened seedlings of various genotypes differed slightly, only in the Pidzymok kharkivskiy variety was slightly lower compared with other studied genotypes. Hardening caused a slight increase in the total content of phenolic compounds in all studied varieties. The total amount of flavonoids in non-hardened seedlings of various genotypes differed slightly. Six-day hardening led to an increase in the content of flavonoids in the seedlings of all studied varieties by 1.7—1.9 times, with no significant differences between varieties. The content of anthocyanins in the non-hardened seedlings of various varieties was different: it was the highest for the Buket variety, and the lowest for the Pidzymok kharkivskiy variety. During the process of cold hardening, it was increasing and had reached approximately the same values in the varieties Buket, Raritet and Alexandra, however, in the least frost-resistant variety Pidzymok kharkivskiy this index was significantly lower. The conclusion about the contribution of anthocyanins, but not secondary metabolites in general, to the formation of frost resistance of triticale seedlings and the antioxidant defense system at low temperatures was made.

Improving the Quality of Production of Sand Core on Core Shooting Machines

The article is devoted to the study of the method of modeling the core shooting process of manufacturing core from cold hardening mixtures (CHM) in the software package Flow-3D, as well as consideration of recommendations on the parameters of the core shooting process, to ensure quality castings of cast iron and steel. This technology of production of cores belongs to technologies which are widely used in foundry production.