The Influence of Osmotic Dehydration in Polyols Solutions on Sugar Profiles and Color Changes of Apple Tissue

The following study aims to evaluate the changes in profile of selected sugars and content of polyols in the apple tissue after osmotic dehydration. What makes this research innovative is the use, in the osmotic pre-treatment, of solutions which have hitherto not been commonly used in fruit processing by researchers worldwide. Selected substances from the polyols group (erythritol, xylitol, and maltitol) were used as osmotic agents in 30 % concentrated solutions. The ideal osmotic pressure, as well as efficiency of the process, was calculated, and these parameters were the highest in the case of erythritol. It was confirmed that type of osmotic solution and time of the process have significant influence on discussed parameters. Osmotic dehydration in polyols solutions resulted in increasing the content of these compounds during the process and minor changes in sugars profile of apple tissue. Color changes caused by pre-treatment were small, but still they could be noticed by an inexperienced observer

Modeling non-linear rheology of PLLA: comparison of Giesekus and Rolie-Poly constitutive models

Rheological models for biobased plastics can assist in predicting optimum processing parameters in industrial forming processes for biobased plastics and their composites such as film blowing, or injection stretch-blow molding in the packaging industry. Mathematical descriptions of polymer behavior during these forming processes are challenging, as they involve highly nonlinear, time-, temperature-, and strain-dependent physical deformation processes in the material, and have not been sufficiently tested against experimental data in those regimes. Therefore, the predictive capability of two polymer models, a classical Giesekus and a physically-based Rolie-Poly, is compared here for extensional and shear rheology data obtained on a poly(L-lactide) (PLLA) across a wide range of strain rates of relevance to those forming processes. Generally, elongational and shear melt flow behavior of PLLA was predicted to a satisfactory degree by both models across a wide range of strain rates (for strain rates 0.05–10.0 s−1), within the strain window up to 1.0. Both models show a better predictive capability for smaller strain rates, and no significant differences between their predictions were found. Hence, as the Giesekus model generally needs a smaller number of parameters, this class of models is more attractive when considering their use in computationally demanding forming simulations of biobased thermoplastics

Stability of chemical reaction fronts in solids:Analytical and numerical approaches

Localized chemical reactions in deformable solids are considered. A chemical transformation is accompanied by the transformation strain and emerging mechanical stresses, which affect the kinetics of the chemical reaction front to the reaction arrest. A chemo-mechanical coupling via the chemical affinity tensor is used, in which the stresses affect the reaction rate. The emphasis is made on the stability of the propagating reaction front in the vicinity of the blocked state. There are two major novel contributions. First, it is shown that for a planar reaction front, the diffusion of the gaseous-type reactant does not influence the stability of the reaction front – the stability is governed only by the mechanical properties of solid reactants and stresses induced by the transformation strain and the external loading, which corresponds to the mathematically analogous phase transition problem. Second, the comparison of two computational approaches to model the reaction front propagation is performed – the standard finite-element method with a remeshing technique to resolve the moving interface is compared to the cut-finite-element-based approach, which allows the interface to cut through the elements and to move independently of the finite-element mesh. For stability problems considered in the present paper, the previously-developed implementation of the cut-element approach has been extended with the additional post-processing procedure that obtains more accurate stresses and strains, relying on the fact that the structured grid is used in the implementation. The approaches are compared using a range of chemo-mechanical problems with stable and unstable reaction fronts.</p

Electrical dual-percolation in MWCNTs/SBS/PVDF based thermoplastic elastomer (TPE) composites and the effect of mechanical stretching

Dielectric thermoplastic elastomers (TPEs) offer a number of advantages over traditional dielectric elastomers or rubbers in terms of tailorable mechanical and electrical properties, higher mechanical strain, and ease of processing and shaping. Such a combination of properties has attracted increasing attention in flexible energy harvesting and storage applications. The combination of styrene–butadiene-styrene (SBS) and poly(vinylidene fluoride) (PVDF) has the potential to provide a combination of high elongation to break and increased relative permittivity, however the immiscibility between SBS and PVDF results in polymer blends with poor stretchability and processing properties. In this work, a dual percolated structure was created in a thermoplastic elastomer of SBS/PVDF (50/50 wt%), by coupling EVA as a compatibiliser for SBS/PVDF with multi-walled carbon nanotubes (MWCNTs) as a conductive filler that created an electrical percolation network. The elongation at break of SBS/PVDF was significantly enhanced by adding 20 wt% of EVA due to the reduced phase dimensions and enhanced interfacial adhesion. The addition of MWCNTs enabled the formation of a percolated network at 1 wt% in the SBS phase, followed by a second percolation at 3 wt% in both PVDF and SBS phases. The relative permittivity of the composite increased to 22.5 at 1 wt% MWCNT with a tan δ of 0.5, and further increased to 34.9 for a 2 wt% of MWCNT concentration while the tan δ remained constant. In-situ electrical testing for the SBS/PVDF thermoplastic elastomer under strain showed that, at 1 wt% MWCNT, the non-percolated PVDF islands acted as variable capacitors whose capacitance increased with degree of stretching. For the dual percolated structure formed at 3 wt% MWCNT, the capacitance and conductivity of the composites were unaffected up to 30% strain. The high relative permittivity and strains of over 100% means that the SBS/PVDF based thermoplastic elastomer is readily suitable for vibration control sensors, variable impedance devices, energy harvesters and artificial muscles and actuators

Pacjent ze złożoną wadą aortalną i dysfunkcją lewej komory - diagnostyka i zasady kwalifikacji zabiegowej

Zwężenie lewego ujścia tętniczego to jedna z najczęstszych wad zastawkowych serca; może mieć charakter wrodzony lub nabyty. W pracy przedstawiono przypadek pacjenta z krytyczną stenozą aortalną i dysfunkcją lewej komory oraz ciężką niedomykalnością trójdzielną. U chorego, mimo znacznego zaawansowania zmian, przebieg kliniczny charakteryzował się umiarkowanym nasileniem objawów. Wykonane echokardiograficzne badanie przezklatkowe pozwoliło na dokonanie rozpoznania i podjęcie decyzji terapeutycznych. Leczenie kardiochirurgiczne (wymiana zastawki aortalnej, plastyka zastawki trójdzielnej) przebiegło bez powikłań i spowodowało ustąpienie objawów, a w obrazie echokardiograficznym - poprawę funkcji lewej komory

Zawał serca u 34-letniej pacjentki. Czy terapia przeciwtrądzikowa niesie ze sobą zwiększone ryzyko zakrzepicy i nagłego zatrzymania krążenia?

Myocardial infarction is still one of the most important problems of modern medicine. Every year in Poland, about100,000 people have a heart attack, and because of its complications several thousand dies. Despite this, there are still cases (especially among young people) where we encounter difficulty in determining the causes of myocardial ischemia. We present a case of myocardial infarction complicated by sudden cardiac arrest (SCA) in 34-year-old female patient, who was treated with anti-acne therapy. It should be noted that the SCA is one of the most serious complications of myocardial infarction, mortality is enormous, and patient survival depends largely on quick and professional resuscitation. That is why it is very important to determine whether patient anti-acne therapy may result in development of this serious condition. The analysis of this case is presented in this article.Zawał serca to jedna z najważniejszych jednostek chorobowych dzisiejszej medycyny. W Polsce na zawał serca zapada rocznie około 100 tys. osób, a z powodu jego powikłań notuje się co roku kilkanaście tysięcy zgonów. Mimo to ciągle zdarzają się przypadki (dotyczy to szczególnie młodych osób), w których napotyka się trudności z ustaleniem przyczyny niedokrwienia mięśnia sercowego. W niniejszym artykule zaprezentowano przypadek zawału serca powikłanego nagłym zatrzymaniem krążenia (SCA) u 34-letniej pacjentki, przewlekle leczącej się z powodu nawracających zmian trądzikowych. Należy nadmienić, że SCA to jedno z najcięższych powikłań zawału serca — śmiertelność jest niezwykle wysoka, a skuteczność niesionej choremu pomocy w głównej mierze zależy od szybkości i doświadczenia osób lub zespołów ratowniczych prowadzących czynności reanimacyjne. Dlatego też bardzo istotne jest ustalenie, czy prowadzona przez pacjentkę terapia przeciwtrądzikowa i przyjmowane przez nią leki mogły się przyczynić do rozwoju tego poważnego stanu