Influence of C content on electrochemical corrosion resistance of nanostructured hardmetals

The influence of C content on the electrochemical corrosion behavior of nanostructured WC-Co hardmetals was investigated. WC powder with an average grain size dBET 95 nm and with an addition of VC and Cr3C2 as a grain growth inhibitors was used as starting powders. The mixtures with 5 wt. % and 10 wt. %Co and 15 wt. %Co were consolidated by sinter-HIP process. The samples were researched by direct current and alternative current techniques in the solution of 3.5 % NaCl at room temperature. Corrosion parameters like corrosion potential (Ecorr), corrosion current density (jcorr), polarization resistance (Rp) were determined by electrochemical techniques. On the basis of conducted research it was found that C content added to the starting mixture significantly influence the electrochemical corrosion resistance; better electrochemical corrosion resistance was observed for samples with lower content of C added and lower magnetic saturation

Tribocorrosion wear of austenitic and martensitic steels

This paper explores the impact of tribocorrosion wear caused by an aggressive acidic media. Tests were conducted on samples made of stainless steel AISI 316L, 304L and 440C. Austenitic steels were tested in their nitrided state and martensitic in quenched and tempered and then induction hardened state. Electrochemical corrosion resistance testing and analysis of the microstructure and hardness in the cross section was carried out on samples of selected steels. To test the possibility of applying surface modification of selected materials in conditions of use, tests were conducted on samples/parts in a worm press for final pressing

Rapid Magnetic Susceptibility Characterization of Coastal Morphosedimentary Units at Two Insular Strandplains in Estonia

Coastal archives of changing hydrometeorological conditions include mineralogical anomalies, such as heavy-mineral concentrations (HMCs) of variable thickness and intensity, which contain varying ferrimagnetic (e.g., magnetite) fractions. As an effective alternative to laborious mineralogical and granulometric analysis, we present the first set of bulk-volume low-field magnetic susceptibility (MS) databases from beach and dune lithosomes in the Western Estonian archipelago: Harilaid cuspate foreland (westernmost Saaremaa Island) and Tahkuna strandplain (northernmost Hiiumaa Island). Readings were conducted both in situ from trench walls and on core subsamples. At the Tahkuna site, late Holocene beach ridges reveal substantially lower values: quartz-dominated dune sequences grade from 5–20 μSI downward to diamagnetically dominated (−1–7 μSI) beach facies. Values are higher (20–140 μSI) in historically reactivated parabolic dunes that are encroaching southward over the strandplain. At the Harilaid site, four beach dune ridges (height: 2–3 m) that span the past 250–300 years show a general increase in mean MS from 320–850 μSI with decreasing age, with peaks of 1000–2000 μSI below the dune crests (depth: ~0.3–0.6 m) likely related to contemporary wind acceleration during ridge aggradation. The highest mineralogical anomalies range from 2000–5500 μSI in the historic dune sections and exceed 8000 μSI along the actively eroding upper-berm segments, typical of HMCs generated by moderate storms. MS anomalies are likely correlated with high-amplitude electromagnetic signal responses in georadar records and provide useful information for optical luminescence sampling strategies. Our study demonstrates that magnetic susceptibility trends provide a useful means of rapidly assessing relative temporal changes in overall wave/wind climates, help identify and correlate discrete anomalies related to extreme events, serve as local beach/dune boundary indicators, and represent potentially quantifiable paleo-energy indices

Manifestation of Heat-Induced Valuable Dietary Nucleotide Salvage in Food Prepared from Aged Fish in Fast Protein and Metabolites Liquid Chromatography, ATP-Bioluminescence Assay, and NMR Spectra

Dietary nucleotides and nucleosides, primarily inosine monophosphate (IMP) and the adenine nucleotide pool (ANP), are widely considered as essential nutrients responsible for multiple biological functions. Food prepared from meat and fish is the main source of these substances in the human diet, and it is extremely important to implement storage and processing techniques ensuring their maximum preservation and even accumulation during maturation or conditioning. In experiments with freshly refrigerated grass carp and defrosted Alaska pollock fillets it was discovered, initially using Fast Protein and Metabolites Liquid Chromatography and the ATP-bioluminescence test, and afterwards validated by NMR spectroscopy, that heat treatment identical to conventional culinary processing in aqueous or wet media at temperatures above 62 °C leads to nucleotide salvage (recovery) in aged fish. A significant increase in the concentration of IMP, and even an emergence of ANP substances, were reliably demonstrated in fish samples which had already partially or fully lost these components during prolonged storage due to the ATP breakdown metabolic reactions. Owing to this recovery, the nutritive value of ready-to-eat food can be higher than was initially evaluated in raw products before heat treatment: an effect that should certainly be considered in practical nutrition. Moreover, it is necessary to reconsider the widely acknowledged system of indices of freshness based on nucleotides and nucleosides elaborated a long time ago for raw meat and fish products