Presented paper shows the mathematical and numerical approaches for modelling of binary alloy solidification solved by the Finite Element Method (FEM). The phenomenon of shrinkage cavities formation ...process is included in the numerical model. Multiple macroscopic cavities can be modelled within the single casting volume. Solid, liquid and gaseous phases with different material properties are taken into account during solidification process. Mathematical model uses the differential equation of heat diffusion. Modification of specific heat is used to describe the heat releasing during liquid-solid phase change. Numerical procedure of shrinkage cavities evolution is based on the recognition of non-connected liquid volumes and local shrinkage computation in the each of them. The recognition is done by the selection of sets of interconnected nodes containing liquid phase in the finite element mesh. Original computer program was developed to perform calculation process. Obtained results of temperature and shrinkage cavities distributions are presented and discussed in details.
The paper presents an approach of numerical modelling of alloy solidification in permanent mold and transient heat transport between the casting and the mold in two-dimensional space. The gap of ...time-dependent width called "air gap", filled with heat conducting gaseous medium is included in the model. The coefficient of thermal conductivity of the gas filling the space between the casting and the mold is small enough to introduce significant thermal resistance into the heat transport process. The mathematical model of heat transport is based on the partial differential equation of heat conduction written independently for the solidifying region and the mold. Appropriate solidification model based on the latent heat of solidification is also included in the mathematical description. These equations are supplemented by appropriate initial and boundary conditions. The formation process of air gap depends on the thermal deformations of the mold and the casting. The numerical model is based on the finite element method (FEM) with independent spatial discretization of interacting regions. It results in multi-mesh problem because the considered regions are disconnected.
Unveiling the attributes of rabbit milk Ludwiczak, A.; Składanowska-Baryza, J.; Kuczyńska, B. ...
Animal,
June 2023, 2023-Jun, 2023-06-00, 20230601, 2023-06-01, Letnik:
17, Številka:
6
Journal Article
Recenzirano
Odprti dostop
•How do the lactation course and the pregnancy affect rabbit milk and kits’ growth?•The diameter of fat globules increases from 5 to 7 µm with ongoing lactation.•Among the FA in rabbit milk, C18: 2 ...and C18: 3 are affected by lactation day.•Only a few milk attributes are affected by the doe’s reproductive status.•Results of this study may help in increasing the survival rate of rabbit kits.
Increasing the knowledge of rabbit milk can help in breeding practice to solve issues considering the health and growth of rabbit kits. The goal of the study was to perform a broad physicochemical analysis of rabbit milk and examine the effect of the reproductive status of the females on daily milk yield and milk attributes. The study was conducted on a commercial rabbit farm and included three consecutive lactations of Hycole does. It has been observed that the daily milk production increased from the 2nd till the 14th day of lactation when does produced almost 300 g of milk daily. The day of lactation caused a significant variation in the content of total solids, solids-not-fat, total protein, casein, lactose, C18: 2, C18: 3, Somatic Cell Count, and pH. The percentage of fat globules categorised according to their diameter changed with the ongoing lactation as well, and the diameter increased from 5 to 7 µm. The percentage of small milk fat globules decreased with lactation day, causing a possible decrease in the digestions rates of milk. Pregnancy had a negative impact on milk production, kits growth performance, and the content of total protein, solids-not-fat, and lactose in milk. Therefore, we can speculate about the negative impact of overlapping lactations and pregnancies on rabbit kits, as their growth is dependent on milk production and composition.
The presented study was a part of the ThermoEye project. The study examined the effect of prudent antibiotic treatment in response to illness on the fattening performance, slaughter traits, and meat ...quality of the pig fatteners. Pigs were divided into an experimental group – EXP and a control – CON. In both groups, the body temperature was monitored, and diseases were confirmed by a veterinarian. In the EXP group, metaphylaxis was used in each case of confirmed disease. The EXP fatteners had greater slaughter weight (by 4.7 kg) and meatiness (by 2.1 percentage points) compared to the CON pigs. The pH in pork was lower in EXP compared to CON pigs. The longissimus thoracis et lumborum of EXP pigs was characterised by a lower cooking loss (28.30 vs. 30.45%) and yellower colour compared to the CON group. Among the amino acids, only the content of histidine (by 5.2%; P < 0.01) and tyrosine (by 7.2%; P < 0.01) was significantly greater in the meat of the CON group compared to EXP, with no effect of sex noted. The content of SFA (by 14.6%; P < 0.05), UFA (by 15.6%; P < 0.05), MUFA (by 17.8%; P < 0.05), MCFA (by 14.1%; P < 0.05), and LCFA (by 15.6%; P < 0.05) was also greater in CON compared to EXP meat. In conclusion, automated monitoring of pig body temperature during the fattening period enables more precise, prudent treatment and effective animal health control while reducing costs due to disease losses and pharmacotherapy. It allows optimal production and affects meat quality.
The paper is focused on the modeling of the directional solidification process of pure metal. During the process the solidification front is sharp in the shape of the surface separating liquid from ...solid in three dimensional space or a curve in 2D. The position and shape of the solid-liquid interface change according to time. The local velocity of the interface depends on the values of heat fluxes on the solid and liquid sides. Sharp interface solidification belongs to the phase transition problems which occur due to temperature changes, pressure, etc. Transition from one state to another is discontinuous from the mathematical point of view. Such process can be identified during water freezing, evaporation, melting and solidification of metals and alloys, etc.
The influence of natural convection on the temperature distribution and the solid-liquid interface motion during solidification of pure copper is studied. The mathematical model of the process is based on the differential equations of heat transfer with convection, Navier-Stokes equation and the motion of the interface. This system of equations is supplemented by the appropriate initial and boundary conditions. In addition the continuity conditions at the solidification interface must be properly formulated. The solution involves the determination of the temporary temperature and velocity fields and the position of the interface. Typically, it is impossible to obtain the exact solution of such problem. The numerical model of solidification of pure copper in a closed cavity is presented, the influence of the natural convection on the phase change is investigated. Mathematical formulation of the problem is based on the Stefan problem with moving internal boundaries. The equations are spatially discretized with the use of fixed grid by means of the Finite Element Method (FEM). Front advancing technique uses the Level Set Method (LSM). Chorin’s projection method is used to solve Navier-Stokes equation. Such approach makes possible to uncouple velocities and pressure. The Petrov-Galerkin formulation is employed to stabilize numerical solutions of the equations. The results of numerical simulations in the 2D region are discussed and compared to the results obtained from the simulation where movement of the liquid phase was neglected.
Human lipoxygenases (LOXs) are the enzymes participating in the metabolism of the polyunsaturated fatty acids and catalyzing their oxidation to a variety of eicosanoids, which as the secondary signal ...transducers have a major impact on human homeostasis. They are involved in many diseases such as inflammatory responses, cancers, cardiovascular and kidney diseases, neurodegenerative disorders and metabolic syndrome. This review summarizes recent developments concerning human 12S-LOX and rabbit 15-LOX projected upon available structural data of LOX and COX oxidoreductases, with conclusions that might apply to LOX family of enzymes in general. Namely: (i) Human lipoxygenases might act as oligomers consisting of active and apo monomers. (ii) Sequential homodimers might act as structural heterodimers with the dimeric interface formed by the interactions resembling the leucine zipper in the coiled-coil superstructure. (iii) Two commonly recognized domains are not sufficient to explain LOX flexibility. Molecular architecture should contain assignment of another regulatory domain of alpha-beta character, possibly important in molecular signaling, which might provide another avenue for targeted drug development. (iv) Allosteric mechanism might involve orchestrated conformational changes and flexibility of the coils connecting the structured elements and ligands binding in more than one monomer.
The objective of the study was to analyse the association of growth hormone (GH1) and C-reactive protein (CRP) loci polymorphisms with reproductive traits in native Pulawska gilts and sows. In the ...GH1 locus, two mutations were identified: one in the second intron single-nucleotide polymorphism (SNP) = rs340429823 in.742C>T, MspI, and one in the second exon (SNP = rs340087546 c.566G>A, HaeII). In the CRP locus, two mutations were found in exon 2 (SNP = rs340175625, NM_213844.2: c.1271A>G, BstNI; and SNP = rs80928546, NM_213844.2: c.788C>T, HinfI). Analysis of sexual activity showed that intensity of external estrus signs differed significantly (P ≤ 0.05) and was the most manifested in gilts with the CT (GH1_MspI) genotype during the second estrus. In case of the CRP gene, statistically significant differences (P ≤ 0.05) were found in terms of the duration of farrowing. The longest farrowings were reported for the GG (CRP_HinfI) and the TT (CRP_BstNI) genotypes and the shortest for the AA (CRP_HinfI) and CC (CRP_BstNI). The most numerous first litters were produced by sows with the AA genotype (CRP_HinfI), with significant differences (P ≤ 0.05) between the AA and GG genotypes. In turn, the CC homozygotes (CRP_BstNI) differed significantly (P ≤ 0.05) in terms of the number of piglets born and reared to day 21 in the second litters compared to the other genotype groups.
Plasminogen activator inhibitor (PAI-1) is a fast acting inhibitor of tissue and urokinase plasminogen activators (tPA and uPA). In that way PAI-1 regulates proteolytic activity of many physiological ...and pathological processes 1-3. PAI-1 plays an important role in blood coagulation controlling clot lysis which is triggered by tPA activated plasminogen 4. Only two types of mutations are reported to be associated with PAI-1; one is the frame-shift mutation in exon 4 of PAI-1 gene resulting in a truncated nonfunctional protein and in complete PAI-1 deficiency. The other SNP causes Ala15Thr mutation in the signal peptide. A literature search revealed five variants of polymorphisms during a study of over one thousand individuals. Two are associated with thrombophilia (765 4G/5G and -844 A>G, in the promoter), risk of myocardial infarction and postoperative deep venous thrombosis related to higher than normal levels of PAI-1. The other SNPs associated with PAI-1 deficiency are Ala15Thr, Val17Ile and they are located in the central hydrophobic core of the PAI-1 signal peptide of PAI-1 and Asn195Ile in the 'A' β sheet of the PAI-1. We have analyzed two SNPs not reported to be associated with PAI-1 deficiency. Our analysis suggests that Val17Ile PAI-1 variant might cause slower PAI-1 secretion leading to the deficiency at time and place where it is needed in a similar way as for Ala15Thr SNP. The Asn195Ile mutant may be more stable only as latent form thus no PAI-1 deficiency is expected in this mutant.
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