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Peculiarities of Embryonic and Post-Embryonic Development of Оesophagostomum dentatum (Nematoda, Strongylidae) Larvae Cultured in Vitro

Abstract

Morphometric peculiarities of the development of Оesophagostomum dentatum Rudolphi, 1803 from egg to infective larva were studied under laboratory conditions at various temperatures. The determined optimum temperature for embryonic and post-embryonic development of О. dentatum larvae from domestic pig (Sus scrofa domesticus Linnaeus, 1758) is 22 °С. At this temperature, 81 % of larvae develop to the third stage (L3) on the 10th day. Temperatures of 24 °С and 20 °С are less favorable for the development of the nematode, at those temperatures only 67 and 63 % of larvae, respectively, reached infective stage by the 10th day of cultivation. Embryonic development of О. dentatum eggs is characterized by their lengthening (by 8.87-9.50 %, р < 0.01) and widening (by 6.77-9.35 %, р < 0.05-0.01), and post-embryonic larval development is associated with lengthening (by 4.59-17.33 %, р < 0.01-0.001).

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Study of the Germination Capacity of Maize Seeds Exposed to Low Temperatures

Abstract

In this paper, were studied three maize hybrids in terms of seed germination capacity when they were exposed to low temperatures. Also, some elements regarding the seed vigor were analyzed, namely the length of the coleoptile, the length of the root and the weight of the germ. Exposure temperatures were 25 ° C (control), 6 ° C and 5 ° C and the hybrids analyzed were Olt, F 376 and Turda 201. The researches were realized under laboratory controlled conditions, and the obtained results showed a strict dependence of the parameters analyzed by the temperature factor.

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Design And Construction Problems Connected With Ensuring Even Thermal Insulation Of Single-Layer Walls

Abstract

The design of single-layer walls appears to be extremely simple. In the opinion of many designers, the additional insulation of tie beams and balconies continues to solve all problems. However, tests on single-layer walls show that the expressed opinion is not valid. The study quotes the results of tests on single-layer walls with strong signs of freezing. The conducted analysis of the design solution and calculation of the fRsi temperature factor on the internal surface and its comparison with fRsi determined empirically enabled reasons behind failure in the construction of the tested walls to be identified. The study presents problems connected with ensuring uniformity of the temperature field in walls, possibilities for detecting areas susceptible to the development of mold, and protection of partitions from the occurrence of this phenomenon by performing appropriate repair works preceding necessary renovations of the building which takes place after the occurrence of mold on walls and ceilings.

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Thermal Bridges At Wood Frame Construction

Abstract

The paper presents the results of numerical analysis on the effects of thermal bridges at wood frame buildings with or without thermal insulation placed on the exterior surface of the wall. The heat flow crossing the wooden thermal bridges, respectively the linear heat transfer coefficients ψ and the temperature factors fRsi, can be established based on the plane temperature field in stationary thermal regime. The “PSIPLAN” computer program used to determine the temperature field, derived from the original program “CIMPLAN” with its first version developed in 1980. The program allows graphic description of the plane section of a thermal bridge and discretizes automatically the section on both axes in accordance with the stipulations of the EN ISO 10211-1:1995 standard and EN ISO 10211:2007 standard. The computer program generates automatically the system of equations that is solved using iterative methods until the heat flows on the two surfaces of the section are balanced. The calculation results are presented with numerical values and in a graphical manner by isothermal surfaces. The program has various libraries that include several types of wood thermal bridges.

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Three-dimensional biomechanical study of functional stresses in composite restorations of masticatory teeth

ABSTRACT

OBJECTIVE: The aim of the present work was to study and evaluate the intensity of stresses in the adhesive bond in composite restorations of masticatory teeth after light-curing, under temperature changes and masticatory loads.

MATERIALS AND METHODS: Data for the 3D model generation of a maxillary premolar were obtained during a routine CT head scan. Thirty-three cross-sections of tooth 25 were selected and used to create a 3D geometric model enmeshed using the fi nite element method (FEM) (made up of 106556 elements and 608724 nodes). The pulp cavity and the periodontal ligament were constructed in the same way and integrated into the premolar model. Eight cavity confi gurations with converging walls were designed, resistant to masticatory forces (enamel/dentin = 1/1). A comparative computer simulation was carried out of the polymerization shrinkage forces of the composite material (CM), temperature changes in the oral cavity and functional masticatory loads. The distribution of the generated stress on the adhesive bond was evaluated in eight different class I and II cavity confi gurations. The location of crack formation was assessed in the cases of rupture of the adhesive bond.

RESULTS: In all cavity confi gurations, stress concentration in the adhesive layer is higher at the interface with the dental tissues. Low temperatures (5 °C) generate forces that are greater than the strength of the adhesive bond in all studied cavity confi gurations. The distribution of the generated stresses under the effect of axial and tangent forces of 300 N is similar to that under the effect of temperature factors. The axial masticatory forces have a pronounced adverse effect on the adhesive bond in all cavity confi gurations.

CONCLUSIONS: Low temperatures and axial masticatory forces play an important role for the marginal integrity. They exacerbate the adverse effects of polymerization shrinkage in composite restorations of masticatory teeth.

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Variation in Reproductive Phenology in a Pinus radiata D. Don Seed Orchard in Northern Spain

on parental balance in a Scots pine clonal seed orchard. Ann. Sci. For. 54: 129-144. BURCZYK, J. and D. PRAT (1997): Male reproductive success in Pseudotsuga menziesii (Mirb). Franco: the effect of spatial structure and flowering characteristics. Heredity 79: 638-347-144. CHUNG, M. S.(1981): Flowering characteristics of Pinus sylvestris L. with special emphasis on the reproductive adaptation to local temperature factor. Acta Forestalia Fennica 169: 1-68. CODESIDO, V. and E. MERLO (2001): Caracterización fenológica del

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Closed system of coupling effects in generalized thermo-elastoplasticity

Interpretation . – Institution of Mechanical Engineers, vol.188. [37] Costa N. and Silva F.S. (2011): On a new temperature factor to predict the fatigue limit at different temperatures. – International Journal of Fatigue, vol.33, pp.624-631. [38] Okrajni J., Junak G. and Marek A. (2008): Modelling of deformation process under thermo-mechanical fatique conditions. – International Journal of Fatique, vol.30, pp.324-329. [39] Baumel A. and Seegler T. (1990): Material Data for Cyclic Loading . – Materials Science Monographs, vol.42A-E, Supplement 1, Elsevier

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