Structural Features of Cast Refractory Alloy HP40NbTi High-Temperature Oxidation. Part I. Evolution of Microstructure and Phase Composition

Metal Science and Heat Treatment - Optical and electron microscopy, x-ray spectral microanalysis, and thermogravimetric analysis in combination with differential scanning calorimetry are used to...     

Crystallography of in-situ transformations of the <Emphasis Type="Italic">M</Emphasis><Subscript>7</Subscript>C<Subscript>3</Subscript> carbide in the cast Fe–Cr–Ni alloy

In the process of holding of the cast heat-resistant Fe–Cr–Ni (0.45C–25Cr–35Ni) alloy at 1150°C, the eutectic chromium carbide present in its structure undergoes a gradual transition M ₇C₃ → M ₂₃C₆. The gradual formation of domains of the M ₂₃C₆ carbide inside the particles of the M ₇C₃ carbide makes it possible to assume that the observed phase transition is the well-known carbide transformation of the in situ type. The mechanism of the in situ transformation of the crystal structure of the carbide from M ₇C₃ into M ₂₃C₆ with a change in the number of nearest metal neighbors of carbon atoms is explained within the previously developed combinatory model of polymorphic transitions in the metals.     

Changes in the vitamin content of various cereals during storage

Thiamine and niacin losses were studied in various cereals (grinding millet, non-grinding oatmeal, fine-ground corn, grinding rice, wheat Poltavskaya, buckwheat, pearl-barley, and grinding pea) stored in sacks at store-houses in two different climatic areas of the USSR - with a temperate and with a dry hot climate, as well as at a constant temperature of 10 degrees C, during 6-29 months. Vitamin losses in grinding millet, non-grinding oatmeal and grinding rice were evaluated considering their treatment with methyl bromide and cereal cooking. It was found that during the storage under conditions of a dry hot climate thiamine and niacin losses comprised 37.8, after methyl bromide treatment - 44.0, and after cooking - 28.6%. Lower vitamin losses were recorded after the cereals storage at a constant temperature of 10 degrees C.     

Experimental investigation of in-situ transformations of the <Emphasis Type="Italic">M</Emphasis><Subscript>7</Subscript>C<Subscript>3</Subscript> carbide in the cast Fe–Cr–Ni alloy

The microstructure and the phase composition of a heat-resistant Fe–Cr–Ni alloy (0. 45C–25Cr–35Ni) has been investigated in the cast state and after annealing at 1150°C for 2–100 h. After a 2-h high-temperature annealing, the fragmentation of the crystal structure of the eutectic M ₇C₃ carbides into domains of ~500 nm in size with a partial transition into M ₂₃C₆ carbides is observed. After a 100-h holding, the complete transition of the hexagonal M ₇C₃ carbides into M ₂₃C₆ with a face-centered cubic structure occurs. The carbide transition M ₇C₃ →M ₂₃ can be considered to be an in situ transformation.     

Bioactive non-coloured polyphenols content of grapes,wines and vinification by-products: Evaluation of the antioxidant activities of their extracts

The comparative quantization of main non-coloured polyphenols, the assessment of total polyphenolic content (TPC) and the detailed evaluation of the antioxidant activities of various grape-based products – from the harvest stage up to the production of the corresponding wines – are presented. The material studied consisted of grape tissues (berries, seeds and skins) of native Greek Vitis vinifera cultivars, which provided polyphenol-rich extracts via an optimized ultrasound extraction procedure, while the respective wine samples were condensed by a novel extraction procedure using XAD-4 adsorption resin column. The extraction methods accuracies were thoroughly validated and the polyphenolic content of extracts was assessed by HPLC–DAD and photometric methods. Their antioxidant properties were evaluated by following assays, modified to fit into a high throughput approach: DPPH radical scavenging, FRAP, inhibition of CuSO₄-induced LDL oxidation and the reduction of intracellular reactive oxygen species (ROS) in smooth muscle cell cultures. Seed samples exhibited the highest TPC values, which are well correlated with their significant antioxidant properties in all assays performed. Of special interest is the significant capability of the tested extracts to prevent the LDL oxidation at very low concentrations. Furthermore, the good correlation between the antioxidant activities assessed for the LDL oxidation inhibition and the intracellular ROS assays is indicative of the possible in vivo antioxidant properties of the extracts. Results herein reveal the considerable antioxidant potential of the Greek grapevine production and exploits their vinification by-products as a potential inexpensive source of high added value antioxidants.