OPTIMUM SHAPE OF THE OPEN CROSS-SECTION OF A THIN-WALLED BEAM

The paper is aimed at searching for the optimum shape of an open cross-section of a thin-walled beam under strength and stability constraints. Variational and parametrical shaping of the cross-section of the beam is employed. The stability constraints include lateral buckling of the beam and local buckling of the walls. The problem is purely mechanical one, and manufacturing constraints are not considered. The objective function is the minimal value of the cross-section area of the beam. Optimal shapes of the beam profiles are shown graphically.     

THE INFLUENCE OF ADDITION OF DEFATTED BLACKCURRANT SEEDS ON PRO‐HEALTH CONSTITUENTS AND TEXTURE OF CEREAL EXTRUDATES

ABSTRACT

Extrudates used in the study were prepared on the base of cornmeal (100%) – control, which was in 10, 30 and 50% replaced by defatted seeds of blackcurrant, which were a by‐product of supercritical fluid extraction, used for oil production. The aim of the study was to check the influence of the level of defatted blackcurrant seeds, on texture and chemical composition of the obtained extrudates. Special attention was paid to pro‐health constituents, i.e., dietary fiber, polyphenols, flavonoids and anthocyanins. The addition of defatted seeds resulted in an increase of polyphenol content, and antioxidant activity, and the rise in the level of flavonoids and soluble dietary fiber as compared with control. The enrichment of extrudates in pro‐health components, as well as improvement of sensory score, suggests that 10% addition of defatted blackcurrant seeds is a suitable level for preparation of extruded fruit‐cereal snacks.

PRACTICAL APPLICATIONS

The study demonstrates that defatted blackcurrant seeds could be a good, natural source of bioactive components in cereal snacks produced by extrusion. The suggested level of this component, optimal from sensory and dietary point of view, is 10%.

     

THE INFLUENCE OF MICROWAVES AND SELECTED MANUFACTURING PARAMETERS ON APPLE CHIP QUALITY AND ANTIOXIDANT ACTIVITY

Apple chips belong to the group of low-processed food products and are an interesting alternative to currently popular snacks. The aim of the work was to estimate the influence of chosen technological parameters on quality and antioxidant properties of apple chips. Thickness of apple slices, drying temperature and initial microwave treatment were analyzed.
On the basis of experimental data, it was established that the drying temperature of 90C was optimal for obtaining products with advantageous sensory value. Apples before drying should be cut into slices 3.5 mm thick and immediately soaked in a solution containing saccharose, apple concentrate, citric acid and SO₂. It was shown that microwave pretreatment of apple slices (150–300 W, 5–10 min) shortened the drying time by about 25% and increased the antioxidant potential by about 30%.

PRACTICAL APPLICATIONS

Because of the increasing incidence of civilization diseases, worldwide interest in snack products that are low in calories and healthy is still growing. The optimum parameters of apple chip production (slice thickness and drying temperature) to obtain a product of high antioxidant potential are presented in this study. It is also shown that application of microwave pretreatment enabled us to shorten the process duration and to reduce the production costs while antioxidant activity remained at a relatively high level.     

Inductive Learning in Civil Engineering: Rough Sets Approach

The paper discusses several potential civil engineering applications of inductive systems based on the theory of rough sets. This theory is discussed briefly. An inductive system is proposed for applications in knowledge acquisition for expert systems, for problem-solving, shallow modeling, learning about different domains, and in learning expert systems.     

A stand‐alone compact EUV microscope based on gas‐puff target source

We report on a very compact desk‐top transmission extreme ultraviolet (EUV) microscope based on a laser‐plasma source with a double stream gas‐puff target, capable of acquiring magnified images of objects with a spatial (half‐pitch) resolution of sub‐50 nm. A multilayer ellipsoidal condenser is used to focus and spectrally narrow the radiation from the plasma, producing a quasi‐monochromatic EUV radiation (λ = 13.8 nm) illuminating the object, whereas a Fresnel zone plate objective forms the image. Design details, development, characterization and optimization of the EUV source and the microscope are described and discussed. Test object and other samples were imaged to demonstrate superior resolution compared to visible light microscopy.     

Evolution of rapidly solidified NiAlCu(B) alloy microstructure

This study concerned phase transformations observed after rapid solidification and annealing at 500, 700 and 800 °C in 56.3 Ni‐39.9 Al‐3.8 Cu‐0.06 B (E1) and 59.8 Ni‐36.0 Al‐4.3 Cu‐0.06 B (E2) alloys (composition in at.%). Injection casting led to a homogeneous structure of very small, one‐phase grains (2–4 µm in size). In both alloys, the phase observed at room temperature was martensite of L1₀ structure. The process of the formation of the Ni₅Al₃ phase by atomic reordering proceeded at 285–394 °C in the case of E1 alloy and 450–550 °C in the case of E2 alloy. Further decomposition into NiAl (β) and Ni₃Al (γ′) phases, the microstructure and crystallography of the phases depended on the path of transformations, proceeding in the investigated case through the transformation of martensite crystallographic variants. This preserved precise crystallographic orientation between the subsequent phases, very stable plate‐like morphology and very small β + γ′ grains after annealing at 800 °C.     

PHYSICO-CHEMICAL CHARACTERIZATION OF MONOMERIC CHEMICALLY PHOSPHORYLATED CASEINS

Casein was phosphorylated under mild conditions with low molar ratios of POCl₃ (25, 50 and 100 mole POCl₃/mole protein) in the presence of equivalent amounts of triethylamine. Consequently, the resulting modified proteins (4–21 mole P/mole protein) had increased negative charges, lower isoelectric points and existed mainly in a monomeric form. The extent of change in functional properties depended mainly on the degree of phosphorylation and the initial caseins.     

Influence of starch retrogradation on the texture of cooked potato tuber

Texture profile analysis applied to whole cooked potato tubers conditioned at 4 and 20°C has shown a significant improvement in texture quality of the potato influenced by starch retrogradation. Conditioning decreases adhesiveness and fracturability and increases cohesiveness and hardness, especially at the lower temperature. The changes were related to soluble starch content, estimated by the Blue Value Index, and to development of a polymeric network within the gelled starch in cooked tuber.