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Inelastic materials that form dislocation cells on being deformed are modeled as a “constrained-mixture” of plastically hard and soft regions by associating different natural states with these regions. The deformation gradient from the reference configuration to the natural configuration is identified as the plastic deformation tensor and the stress is measured from a changing set of natural configurations. Two sets of natural configurations are introduced: one for the hard phase and the other for the soft phase. The full elastic response of the body is determined by elastic responses from different natural configurations. The energy stored in the dislocation networks is explicitly accounted for in the Helmholtz potential. Within a specialized constitutive set up, the soft phase is assumed to be non-hardening while the hardening response of the hard phase is dependent upon the response of both the hard and soft phases. These special forms are used to model the response of the material that forms cellular structures when subjected to cyclic loading. [ABSTRACT FROM AUTHOR]

The study deals with the modification of mechanical properties of poly (!-caprolactone) (PCL)/poly(lactic acid) (PLA) system using the microfibrillar composite (MFC) concept. As the in-situ formation of PLA fibrils by melt drawing was impossible due to flow instability during extrusion, the system was modified by adding halloysite nanotubes (HNT) using different mixing protocols. The resulting favourable effect on the rheological parameters of the components allowed successful melt drawing. Consequently, PLA fibrils formation combined with the reinforcement of components by HNT and increased PLA crystallinity lead to a biocompatible and biodegradable material with good performance suitable for a broad range of applications. The best results, comparable with analogous MFC modified with layered silicate (oMMT), have been achieved at a relatively low content of HNT of 3%, in spite of its lower reinforcing ability in a single nanocomposite. This indicates that modifying MFC by HNT, including fibrils and interface parameters, is more complex in comparison with the undrawn system.

The objective of this field trial was to evaluate the body temperature within the interval of 10 days post partum in cows with puerperal metritis, as confirmed by a clinical examination, in comparison with cows without clinical symptoms of this disease. In addition, the body temperature in cows having a purulent and putrid character of lochia was compared. Rectal temperature was measured daily in 92 randomly selected cows. The cows were examined clinically on day 10 ± 3 post partum and were divided according to the character of lochia into Group M1 (purulent lochia, n = 29), Group M2 (putrid lochia, n = 28) and Group C (normal lochia, n = 35). The number of cows with a fever (temperature > 39.0°C or > 39.5°C) at least once during 10 days post partum was higher in Groups M1 and M2 compared to Group C (86.2% and 92.9% vs. 54.3%, P < 0.01 and P < 0.001, or 41.4% and 71.4% vs. 14.3%, P < 0.05 and P < 0.001). In addition, there was a higher number of cows with a temperature > 39.5°C in Group M2 in comparison with Group M1 (P < 0.05). More cows showed consistent temperatures > 39.0°C for three days or > 39.5°C for two days in Group M2 compared to Group C (42.9% vs. 8.6%, P < 0.01 or 25.0% vs. 2.9%, P < 0.05). Average daily temperatures were higher in Group M2 compared to Group C on Days 1, 3, 5 and 7 (PP < 0.05) as well as on Days 2 and 6 (P < 0.01) post partum. The results reveal the following: higher incidence of body temperature > 39.0°C in cows with puerperal metritis; risk period for fever from Day 3 to Day 7 post partum; higher incidence of fever in cows with putrid lochia compared to cows with purulent lochia; body temperature > 39.5°C being a more accurate indicator of puerperal metritis than temperature > 39.0°C. Despite that, the occurrence of fever was irregular. In conclusion, measurement of body temperature does not represent a sufficiently accurate diagnostic method for puerperal metritis although it may be considered a useful indicator for assessment of the severity of the disease.