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W pracy prezentuje sie zachowanie betonu przy obciazeniach quasi-statycznych przy jednoosiowym sciskaniu i rozciaganiu oraz w płaskim stanie naprezenia. Dyskutowane sa kryteria zniszczenia betonu oraz metody identyfikacji parametrów konstytutywnych. Istotnym elementem jest równiez energetyczna interpretacja omawianych kryteriów. Zawarto przykład numeryczny wykorzystujacy model materiału betonu plastycznego ze zniszczeniem, który dowodzi prawdziwosci opisu konstytutywnego na podstawie wyników eksperymentalnych.

Thirty two Holstein calves were used to investigate the effects of sodium butyrate (SB), phytogenic compounds (PC; consisting mainly of caraway, liquorice extract, oak bark and vanilla flavour), and egg yolk antibodies (EY) supplementation in milk replacer (MR) containing probiotic bacteria on the counts of total bacteria and selected bacteria in faeces. The calves were fed a mixture of surplus colostrum, transition milk and whole milk for the first 9 days of life. On day 10, they were assigned to one of four treatments (8 calves/ treatment): 1) MR containing probiotic bacteria but no other feed additives (control treatment; CTRL); 2) MR with SB; 3) MR with PC; and 4) MR with EY. On day 14 of the study, total bacteria counts were higher in EY calves, Lactobacillus spp. counts were higher in PC and EY calves, and Bifidobacterium spp. counts were higher in SB, PC and EY calves compared to CTRL calves. Escherichia coli counts were higher in EY calves and tended to be higher in SB calves compared to CTRL. On day 28 of the study, total bacteria counts tended to be lower in PC calves, Lactobacillus spp. counts were higher, while Clostridium perfringens counts were lower in EY calves compared to CTRL calves. It was concluded that the supplementation of SB, PC and EY in MR already containing probiotic bacteria may either increase or reduce the abundance of beneficial (Lactobacillus spp. and Bifidobacterium spp.) but also undesired (E. coli, and C. perfringens) bacteria in calf faeces. Of the investigated feed additives, PC supplementation exerted the most beneficial effect on the composition of faecal bacteria, while EY supplementation can reduce C. perfringens shedding in faeces. [ABSTRACT FROM AUTHOR]

Experimental tests were carried out on poly(Methyl Methacrylate) (PMMA) in order to define its mechanical behaviour over a wide range of temperature. To reach high strain rate, perforation tests were performed within a wide range of temperatures using a high-performance oven, from room temperature to 130 °C, above the glass transition temperature Tg. In addition, the results were confronted with compression tests previously obtained. Based on experiments, the temperature transition between fragile and ductile was defined. The material became fully ductile above 118 °C inducing no cracking and debris during the perforation process. The yield stress evolution as function of strain rate for various temperatures was modelled by using the cooperative model. The model predictions were in agreement with experimental data. Two material models developed by Richeton and Nasraoui were analysed, the latter was then implemented into the FE model to simulate perforation tests for a wide range of temperatures and strain rates. It was observed that the coupling strain rate-temperature is a key factor to predict the structure behaviour not only in terms of material behaviour but also in terms of dynamic failure.

This paper presents the mechanical behavior of thermally sprayed coatings produced using an arc wire coating material. The produced coatings were cut and subjected to strength resistance tests in static and in dynamic loading. The compressive behavior for the strain rates between 0.001 1/s and 2612 1/s was examined. The strain rate sensitivity of the material was recognized in the material during dynamic loading using the SHPB technique. Microstructural observations were made, and properties such as changes in porosity and the microhardness of the coatings tested were examined. A significant reduction in coating porosity was demonstrated after static loading (90%) and dynamic loading (86%). The result of porosity reduction is the strengthening of the coatings through an increase in the microhardness of these coatings after loading in the static test (160 HV 0.3/8) and the dynamic test (278 HV 0.3/8). As a result of the tests, the coatings retain their cohesion and remain consistent. At the same time, they can absorb a significant amount of mechanical energy due to plastic deformation and porosity reduction. The presented results concern a completely new coating material created from a core wire.

Aim: To assess the feasibility of delirium screening with the screening tool 4AT conducted by stroke unit nurses., Design: Observational., Methods: Patients with confirmed acute stroke admitted to the stroke unit at Baerum Hospital, Norway, from March to October 2020, were consecutively recruited. Nurses performed delirium screening using the rapid screening tool 4AT within 24 h of admission, at discharge and when delirium was suspected, and filled out a questionnaire assessing their experiences with the delirium screening. A geriatrician validated the delirium diagnosis., Results: In all, 62 patients were included, mean age 73.3 years. 4AT was performed according to protocol in 49 (79.0%) and 39 (62.9%) patients at admission and discharge respectively. Lack of time (40%) was reported as the most common reason for not performing delirium screening. The nurses reported that the felt competent to carry out the 4AT screening, and did not experience it as significant extra workload. Five patients (8%) were diagnosed with delirium. Delirium screening performed by stroke unit nurses seemed feasible and the nurses experienced that 4AT was a useful tool for this purpose., (© 2023 The Authors. Nursing Open published by John Wiley & Sons Ltd.)

In presymptomatic amyotrophic lateral sclerosis (ALS), spinal motoneurons (MNs) have reduced firing patterns and synaptic excitation levels. Preliminary data indicated that in the SOD1 G93A mouse model of ALS, monosynaptic excitatory postsynaptic potentials (EPSPs) evoked in spinal MN by Ia proprioceptive afferent stimulation could be facilitated by trans-spinal direct current stimulation (tsDCS). However, which element of the Ia afferent-MN circuit is affected by tsDCS, and whether tsDCS-induced EPSP facilitation is a general phenomenon or specific to the superoxide dismutase type-1 (SOD1) Glycine to Alanine substitution at position 93 (G93A) mutation, remain to be determined. In this study, we have applied 15-minute tsDCS to the lumbar segments of presymptomatic SOD1 and wildtype (WT) mice and explored its impact on MN passive membrane properties, EPSP amplitude, and Ia afferent activity. While anodal tsDCS induced short-lasting EPSP facilitation in both SOD1 and WT mice, Ia afferent activity and passive membrane properties were altered only in SOD1 mice. Interestingly, EPSP amplitudes of SOD1 mice remained facilitated for at least 1 h after current application, but no long-lasting effect was observed in WT mice. Moreover, anodal tsDCS failed to induce any long-lasting changes in MN passive membrane properties in both SOD1 and WT mice. Conversely, cathodal tsDCS decreased Ia afferent induced EPSP amplitudes only during current application in SOD1 MNs, and no significant effects on Ia afferents excitability were observed. Our findings indicate the high susceptibility of SOD1 MNs to tsDCS and highlight the potential of this neuromodulation technique for the treatment of ALS., (Copyright © 2022 IBRO. Published by Elsevier Ltd. All rights reserved.)

The article presents selected types of phase change materials (PCM) and their properties in terms of applications in various fields of science such as construction and concrete technology. The aim of the article is to present a comparative analysis between the results of the laboratory tests and numerical simulations. The analysis contains two types of PCM (powder and in liquid), which were dosed in a hybrid system to the concrete mix. The purpose of using PCM is to allow the technological barrier to be exceeded in hot and dry climate conditions, enabling the construction of non-cracking concrete structures. The paper presents a parametric analysis of the influence of various modeling elements on the obtained results. The procedure of generating and absorbing heat caused by the applied PCM was also implemented using user subroutine into finite element code (Abaqus/Standard). The numerically obtained results are consistent with the experimental results. The presented results demonstrate that the use of PCM improves the conditions of concrete maturation by reducing the average temperature of the mixture in its entire volume.

In this paper, perforation experiments were carried out and numerically modelled in order to analyze the response of 2024-T3 aluminum alloy plates under different initial temperatures T 0 . This alloy has a particular relevance since it is widely used as a structural component in aircrafts, but it is also interesting for other sectors of industry. A gas gun projectile launcher was used to perform impacts within initial velocities V 0 from 40 m/s to 120 m/s and at temperatures varying from 293 K to 573 K. A temperature softening of the material was observed which was manifested in the reduction in the ballistic limit by 10% within the temperature range studied. Changes in the material failure mode were also observed at different test conditions. Additionally, a finite element model was developed to predict the material response at high velocities and to confirm the temperature softening that was observed experimentally. An optimization of the failure criterion resulted in a reliable model for such mild aluminum alloys. The results reported here may be used for different applications in the automotive and military sectors.

The originally performed perforation experiments were extended by compression and tensile dynamic tests reported in this work in order to fully characterize the material tested. Then a numerical model was presented to carry out numerical simulations. The tested material was the common brass alloy. The aim of this numerical study was to observe the behavior of the sample material and to define failure modes under dynamic conditions of impact loading in comparison with the experimental findings. The specimens were rectangular plates perforated within a large range of initial impact velocities V 0 from 40 to 120 m/s and in different initial temperatures T 0 . The temperature range for experiments was T 0 = 293 K to 533 K, whereas the numerical analysis covered a wider range of temperatures reaching 923 K. The thermoelasto-viscoplastic behavior of brass alloy was described using the Johnson-Cook constitutive relation. The ductile damage initiation criterion was used with plastic equivalent strain. Both experimental and numerical studies allowed to conclude that the ballistic properties of the structure and the ballistic strength of the sheet plates change with the initial temperature. The results in terms of the ballistic curve V R (residual velocity) versus V 0 (initial velocity) showed the temperature effect on the residual kinetic energy and thus on the energy absorbed by the plate. Concerning the failure pattern, the number of petals N was varied depending on the initial impact velocity V 0 and initial temperature T 0 . Preliminary results with regard to temperature increase were recorded. They were obtained using an infrared high-speed camera and were subsequently compared with numerical results.

In this paper, experimental and numerical results of an aluminum alloy's mechanical behavior are discussed. Over a wide range of strain rates (10 -4 s -1 ≤ έ ≤ 10 3 s -1 ) the influence of the loading impact, velocity and temperature on the dynamic response of the material was analyzed. The interface friction effect on the material's dynamic response is examined using a split Hopkinson pressure bar (SHPB) in a high temperature experiment using finite element analysis (FEA). The effect of different friction conditions between the specimen and the transmitted/incident bars in the SHPB system was examined using cylinder bulk specimens and cylinder plates defined with four-layer configurations. The results of these tests alongside the presented numerical simulations allow a better understanding of the phenomenon and reduces (minimizes) errors during compression tests at high and low strain rates with temperatures ranging from 21 to 300 °C.

This paper presents an analytical prediction coupled with numerical simulations of a split Hopkinson pressure bar (SHPB) that could be used during further experiments to measure the dynamic compression strength of concrete. The current study combines experimental, modeling and numerical results, permitting an inverse method by which to validate measurements. An analytical prediction is conducted to determine the waves propagation present in SHPB using a one-dimensional theory and assuming a strain rate dependence of the material strength. This method can be used by designers of new SPHB experimental setups to predict compressive strength or strain rates reached during tests, or to check the consistencies of predicted results. Numerical simulation results obtained using LS-DYNA finite element software are also presented in this paper, and are used to compare the predictions with the analytical results. This work focuses on an SPHB setup that can accurately identify the strain rate sensitivities of concrete or brittle materials.