Reductions: precontact versus presymplectic Grabowska, Katarzyna; Grabowski, Janusz
Annali di matematica pura ed applicata,
12/2023, Letnik:
202, Številka:
6
Journal Article
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We show that contact reductions can be described in terms of symplectic reductions in the traditional Marsden–Weinstein–Meyer as well as the constant rank picture. The point is that we view contact ...structures as particular (homogeneous) symplectic structures. A group action by contactomorphisms is lifted to a Hamiltonian action on the corresponding symplectic manifold, called the symplectic cover of the contact manifold. In contrast to the majority of the literature in the subject, our approach includes general contact structures (not only co-oriented) and changes the traditional view point: contact Hamiltonians and contact moment maps for contactomorphism groups are no longer defined on the contact manifold itself, but on its symplectic cover. Actually, the developed framework for reductions is slightly more general than purely contact, and includes a precontact and presymplectic setting which is based on the observation that there is a one-to-one correspondence between isomorphism classes of precontact manifolds and certain homogeneous presymplectic manifolds.
The concept of shear-induced structuring was applied to concentrated blends of soy protein isolate (SPI) and wheat gluten (WG) to create novel semi-solid food textures. Concurrent simple shear ...deformation and heating (95°C) of the protein blends generated original structures consisting of fibers or layers. The ratio of SPI to vital WG and the final concentration determined the morphology of the structure. It is hypothesized that the spatial distribution of the SPI-rich phase and the WG-rich phase in a blend was altered by the shear flow. When both phases became aligned horizontally in the shear cell, a fibrous structure was formed; when they became aligned vertically in the shear cell, a layered structure was formed. The structures obtained were analyzed visually and using texture analysis and scanning electron microscopy.
•Simple shear flow leads to formation of anisotropic structures from plant derived protein.•Soy protein form layered structures in simple shear flow.•Blends of soy and gluten protein were converted into fibrous and layered structures.•Mild shear at 95°C allows formation of solid anisotropic food texture from plant proteins.
This research presents the formation of anisotropic, and partly fibrous, semi-solid structures with Soy Protein Concentrate (SPC) using the concept of shear-induced structuring. The morphological and ...mechanical properties of the structures obtained are analyzed using confocal scanning laser microscopy (CSLM), and large scale mechanical deformation analysis. We present process conditions leading to the formation of anisotropic structures in SPC and found that comparable conditions did not result in anisotropy when using soy protein isolate. Results indicate the importance of the dry matter content, the process temperature and the presence of carbohydrates in structure formation. CSLM pictures show that carbohydrates form a separate phase in the system, which is oriented upon processing. The need for high temperatures also required the development of next generation shearing equipment.
•Shear-induced structuring leads to the formation of anisotropic structures in SPC.•Dry matter content, rotational speed and process temperature are important.•Polysaccharides in SPC have an important role in structure formation.
We present a combined time domain NMR and rheology approach to quantify the water distribution in a phase separated protein blend. The approach forms the basis for a new tool to assess the ...microstructural properties of phase separated biopolymer blends, making it highly relevant for many food and non-food related applications. First, we determine the relaxation rate of absorbed water, and the viscoelastic properties of the separated phases as function of the water content. Next, the same properties are measured for the protein blends. Finally, predictions for water distribution obtained from rheological experiments are made via the polymer blending law, and compared to a more direct assessment of the water distribution with time-domain NMR relaxometry (TD-NMR). In this study, the protein blend consists of soy protein isolate (SPI) and vital wheat gluten (WG). We demonstrate that predictions for water distribution are similar for both TD-NMR and rheological measurements. It turns out that water does not distribute homogenously over the phases. Independent of the SPI and WG ratio, more water is absorbed by the SPI phase relative to the WG phase, which largely determines the resulting rheological properties of the blends.
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•TD-NMR is an adequate method for determining the water distribution in a SPI-WG blend.•The viscoelastic properties of SPI-WG blends are determined by the water distribution between both phases.•Water distributions derived from TD-NMR are in agreement with predictions made from rheological properties.•Combination of TD-NMR and rheology can be used to describe the structure (formation) in dense biopolymer blends.
Możliwość udziału organizacji społecznej w postępowaniu administracyjnym wypełnia zasadę wolności zrzeszania się zawartą w Konstytucji RP. Tematem artykułu jest przedstawienie zagadnień związanych z ...ogólnymi zasadami udziału zrzeszeń, zwłaszcza organizacji ekologicznych, w postępowaniu administracyjnym oraz charakterystyka regulacji szczególnych wprowadzonych w tym zakresie przez ustawodawcę.
Nonwovens are one of the most versatile textile materials and have become increasingly popular in almost all sectors of the economy due to their low manufacturing costs and unique properties. In the ...next few years, the world market of nonwovens is predicted to grow by 7%–8% annually (International Nonwovens & Disposables Association INDA, European Disposables and Nonwovens Association EDANA, and Markets and Markets). This article aims to analyze the most recent trends in the global export and import of nonwovens, to present two case studies of Polish companies that produce them, and to present one special case study of the market of nonwoven geotextiles in China and India, which are the Asian transition economies among the BRICS countries (Brazil, Russia, India, China, and South Africa).
The article is an invitation to the Autex 2022 - 21
World Textile Conference, which is organized by the Faculty of Material Technologies and Textile Design, Lodz University of Technology, Lodz, ...Poland. The conference will be held ONLINE on the 7
to the 10
June 2022, under the motto Passion for innovation. The conference will be focused on the latest scientific and technical achievements in the field of textiles.
The development of civil aviation, and hence the increased use of airport infrastructure, leads to the exceeding of environmental noise standards. The subject of this article is to present the issues ...related to the possibility of introducing restrictions and bans to reduce noise generated at airports.
This paper describes the modelling of the structure and mechanical parameters of rope components made of natural fibers. Modern X-ray micro-tomography (Micro-CT) was employed to measure the ...parameters of the internal structure of the multi-component yarns making up rope and utilized as a basic model of twisted rope. The results allowed calculation of the tensions generated in the component yarns and detection of the unevenness of the filling of the component yarns by fibers, which was clearly visible in cross-section. The unevenness of twist measured as a function of distance from the center of the yarn was also detected. The unevenness of fiber distribution in the twisted element decreased its intensity, starting from the surface of the yarn and going deeper into the structure. Migration of the fibers in the frame of the circumference of the component yarns was associated with the mutual slide of single fibers.
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