Influence Of Thermal Processing Research Articles

Influence of thermal processing on sensory profile of crayfish meat

The present study examined the outcomes of boiling (BO), air frying (AF), and boiling combined with air frying (BO-AF) methods on the appearance, texture, taste, and flavor of crayfish meat through a combination of sensory and instrumental analyses. The Free Choice Profiling and Check-All-That-Apply results showed that the BO-AF group had the highest overall acceptability. The BO-AF group presented an attractive golden color, crispy outside, and tender inside characteristics in appearance and texture. However, there was a loss of umami and sweetness in crayfish meat from the AF and BO-AF groups compared to the control (CK) and BO groups. Crayfish meat was identified as containing 42 volatile compounds. Among them, aldehydes and heterocyclic compounds were the main volatile compounds in the AF and BO-AF groups. In particular, the pyrazine compounds were produced by the thermal decomposition of methionine and cysteine. They gave the crayfish meat of the AF and BO-AF groups their characteristic roasted aroma and good color. However, compared to the AF group, the BO-AF group had the characteristic baking aroma of the AF group, as well as a floral and fruity aroma due to the presence of the boiling treatment.

Regional Variability in Sugar and Amino Acid Content of U.S. Soybeans and the Impact of Autoclaving on Reducing Sugars and Free Lysine.

Exploring the sugar and amino acid content variability and the influence of thermal processing on these in soybeans can help optimize their utilization in animal feed. This study examined 209 samples harvested in 2020 and 55 samples harvested in 2021 from across the U.S. to assess their sugar variability and amino acid variability. Harvest regions included the East Corn Belt, West Corn Belt, Mid-South, East Coast, and the Southeast of the U.S. In addition to the sugar and amino acid contents, protein, oil, and seed size were also analyzed. Samples from 2021 were evaluated for their sugar and amino acid contents before and after autoclaving the seeds at 105-110 °C for 15 min. For the samples harvested in 2020, sucrose (4.45 g 100 g-1) and stachyose (1.34 g 100 g-1) were the most prevalent sugars. For the samples harvested in 2021, L-arginine (9.82 g 100 g-1), leucine (5.29 g 100 g-1), and glutamate (4.90 g 100 g-1) were the most prevalent amino acids. Heat treatment resulted in an 8.47%, 20.88%, 11.18%, and 1.46% median loss of free lysine, sucrose, glucose, and fructose. This study's insights into the variability in sugar and amino acid content and the heat-induced changes in the nutritional composition of soybeans provide a reference for improving soybean quality assessment and optimizing its use in animal feed formulations in the U.S.

Quantification of sixteen cannabinoids in hemp seed edible oils and the influence of thermal processing on cannabinoid contents and profiles

To investigate cannabinoid content and profiles, 16 cannabinoids were quantified in 30 commercial hemp seed edible oils. In addition, one hemp seed oil was subjected to thermal processing up to 200 °C for up to 60 min. UHPLC-MS/MS was used for analysis. The content of cannabinoids in the samples ranged from 9 to 279 mg kg−1 (sum) and for Δ9-tetrahydrocannabinol (Δ9-THC) from 0.2 to 6.7 mg kg−1. Three samples exceeded the EU Δ9-THC equivalent maximum levels of 7.5 mg kg−1 for hemp seed oils. Cannabinoid profiles can provide indications of different product characteristics (e.g. degree of processing, variety of plant material). Furthermore, intense thermal processing (200 °C, 60 min) led to 38% decrease in sum cannabinoid content (sum of all analysed cannabinoids in this study), 99% decrease in cannabinoid acids, and 22% increase in Δ9-THC.

Comparative Analysis of Vitamin, Mineral Content, and Antioxidant Capacity in Cereals and Legumes and Influence of Thermal Process.

Cereals, as the world's most consumed food, face challenges related to nutrient quality due to climate change and increased production impacting soil health. In this study, we investigated the vitamin and mineral content, polyphenols, and antioxidant activity in cereals from Western Romania, analyzing whole and hulled wheat, rye, oat, and soybeans before and after heat treatment. Samples from 2022 crops were processed into dough and subjected to 220 °C for 30 min. The results reveal that, despite efforts to optimize nutrient content, cereals, particularly after heat processing, exhibited lower vitamin and mineral levels than the recommended daily intake. The decrease in polyphenols and antioxidant capacity was notable, with rye flour experiencing the largest decline (15%). Mineral analysis showed copper levels in decorticated wheat decreased by 82.5%, while iron in rye decreased by 5.63%. Soy flour consistently displayed the highest calcium, magnesium, and potassium levels, whereas oat flour had the highest zinc and copper levels before and after heat processing. The study highlights the concerningly low vitamins and minerals contents in cereals, as well as in the final products reaching consumers in the Western part of Romania, and contributes to the assessment of measures that are meant to improve the contents of these minerals.

Evolution of microstructure and mechanical properties of a Ti80(CoFeNi)20 ultrafine eutectic composite during thermal processing

In this study, the influence of thermal processing on phase transformation and microstructural evolution of Ti80(CoFeNi)20 ultrafine eutectic composites was investigated. The as-cast alloy exhibited the typical hypoeutectic microstructure consisting of a number of β-Ti dendrites and the β-Ti + Ti2Ni-type ultrafine eutectic matrix. In comparison with the as-cast alloy, the alloy annealed at 1173 K for 1 h exhibited significant microstructural change from a hypoeutectic structure to a microscale dual-phase structure comprising the dispersed Ti2Ni-type phase and β-Ti matrix domain. The alloy aged at 873 K for 1 h exhibited a significant phase transformation from the β-Ti matrix to α-Ti and Ti2Ni-type phases by the eutectoid decomposition. These microstructural evolutions induced by heat treatment significantly influenced to the mechanical properties. Optimized mechanical properties (yield strength of 1530 MPa and plasticity of 5.7%) were achieved for the as-annealed alloy.

Effect of Elevated Temperature and Annealing Time on Mechanical Properties of Ti/Cu Bimetal

The paper presents the results of the elastoplastic properties of Ti/Cu bimetallic rods. They were obtained by extrusion and composed of a copper core with a covered titanium layer. Experiments were carried out at room temperature on virgin samples, and samples were subjected to prior annealing in the temperature range of 600-900 °C for 30, 60, and 90 min. The modern technique of impulse excitation of vibration was used to analyze the elastic properties of bimetal, obtaining the temperature and time characteristics of Young's modulus, internal friction, and resonance frequency variability. Subsequently, the samples were stretched to breakage, obtaining information on the values of limit stresses, their deformability, and the energy demand for uniform elastic-plastic deformation in terms of the effect of temperature and annealing time. The influence of thermal processes on the strengthening of the Ti/Cu bimetal was also examined, and microscopic observations and qualitative analysis of the diffusion zone at the interface of the phases were carried out. The research was to answer the question of how a short-term temperature increase in 600-900 °C affects the physical properties of Ti/Cu bimetallic rods. These rods were used as a high-density electric current carrier in metallurgical processes in environments of aggressive chemical compounds. Studies have shown that short-term annealing at elevated temperatures causes a drastic reduction in the strength of the Ti/Cu bimetal, leading to structural changes within the components, and the diffusion zone with the release of intermetallic compounds, leading to structural degradation. Heating at 900 °C for 60 and 90 min caused accelerated interface degradation and destruction of the Ti/Cu bimetal by delamination.

Influence of thermal processing on the quality of hawthorn: Quality markers of heat-processed hawthorn.

Hawthorn and its derived products are used worldwide as foods as well as complementary medicine. During the preparation of hawthorn, heating and thermal processing are frequently reported. The thermal processing will change the medicinal purposes and modify the efficacy of hawthorn. However, details including the chemical profile shifting and quality markers of heat-processed hawthorn have not been well understood. In this study, we analyzed the hawthorn samples processed at different temperatures and different times by ultraviolet visible absorption spectrum and liquid-mass spectrometry technologies combined with multivariate statistical analysis. It was revealed for the first time that thermal processing could greatly change the ultraviolet-visible absorption spectra and chemical profiles of hawthorn even with heat treatment at 130°C for 10min. And the ultraviolet visible absorption spectrum, especially the ratio value (RA500nm/400nm ), was a descriptive and qualitative indicator of heating degree for the thermal processing at the macroscopic level. Several components, such as hyperoside, chlorogenic acid, quercetin, and apigenin, decreased or increased in content during the processing, and they could be utilized as the chemical quality markers. The proposed quality markers for heat-processed hawthorn will be helpful for further optimizing the processing conditions of hawthorn.

Guided Gradual Egg-Tolerance Induction in Hen's Egg Allergic Children Tolerating Baked Egg: A Prospective Randomized Trial.

BackgroundOver the last few years, studies have shown that the majority of egg allergic children tolerate baked egg (e.g., cake), and that consuming baked egg accelerates the resolution of egg allergy. However, few prospective studies demonstrate the step-wise reintroduction of egg at home after developing baked egg tolerance. Although this could have a positive impact on the children's quality of life and nutrition. Additionally, research supporting the theoretical concept that heating in the presence or absence of wheat causes reduced allergenicity of egg proteins is limited.ObjectiveTo investigate the clinically most favorable duration of gradual egg-tolerance induction in baked egg tolerant children at home, with regard to complete raw egg tolerance.MethodsBaked egg tolerant children above 12 months of age were randomly assigned to a short- or long arm protocol. In the short arm, egg-tolerance induction was studied over 18 months compared to 30 months in the long arm. Children were guided through this protocol involving the step-wise introduction of increasingly allergenic forms of egg starting with baked egg offered as cake, followed by hard-boiled egg, omelet/waffle/pancake, soft-boiled egg, and finally raw egg. We hereby designed this protocol based on the influence of thermal processing in the presence or absence of wheat on egg proteins, as investigated by ELISA, SDS-PAGE, and immunoblotting. At inclusion, children either passed an in-hospital cake challenge or had ovomucoid sIgE ≤1.2 kUA/L, which was considered safe for introduction at home.ResultsGel electrophoresis revealed that the ovalbumin band became weaker with heating, while the ovomucoid band remained stable. In accordance, the IgE-binding to ovalbumin decreased with extensive heating, as opposed to ovomucoid. However, heating in the presence of wheat led to a decreased IgE reactivity to ovomucoid. Of the 78 children in the intention-to-treat group, 39 were randomized to each arm. Fifty-eight children reached the raw egg tolerance endpoint, of which 80% were in the short arm and 69% in the long arm. Within the short arm, the median time to raw egg tolerance was 24 months (95% CI, 21–27 months) compared to 30 months (95% CI, 28–32 months) in the long arm (p = 0.005). No grade IV reactions or cases of eosinophilic esophagitis were observed. The short arm was considered to be non-inferior to the long arm.ConclusionOur gradual short arm protocol appears to be safe and allows clinicians to guide baked egg tolerant children toward raw egg tolerance at home. The allergenicity of the egg proteins was affected by heating temperature and duration, as well as the presence of wheat.

​Thermal Processing and Fermentation Improves the Physicochemical and Functional Properties of Dehydrated Agathi Leaves (Sesbania grandiflora L.)

Background: Green leafy vegetables (GLVs) are seasonal and perishable nature. It undergoes substantial-quality changes immediately after harvest that may lead to loss of its freshness. Hence this experiment was aimed to process and preserve Agathi leaves by dehydration and study the influences of thermal processing and fermentation on its physicochemical and functional properties. Methods: Agathi leaves were separted from stalks, cleaned, washed then subjected to thermal treatments such as boiling (20 min), simmering (10 min) and steaming (10 min) followed fermentation with Baker’s yeast (3% w/w concentration, 20 hours incubation at pH 6.5, 30°C temperature). The processed leaves were cabinet dried at 60°C for 4-5 hours then powdered and stored in an airtight container. The physicochemical and functional properties of the Agathi leaf powders were determined by following standard methods. Result: The processed Agathi leaf powders contain 5.60-8.10% moisture, 35.12-45.90g/100g protein, 6.47-11.41g/100 g minerals and 7.74-9.75 g/100 g crude fibre. Bulk density, Water absorption capacity, Oil absorption capacity, Emulsifying activity and Foaming capacity of the leaf powders were ranged from 0.56 to 0.67g/mL, 2.69 to 3.95 g/g, 0.96 to 1.23 g/g, 48.26 to 67.73% and 23.06 to 51.83% respectively. Thermal and fermentation treatments have significantly changed/altered the physicochemical and functional properties of Agathi leaf powders. The findings suggest that Agahti leaf powder is rich in protein, minerals and crude fibre and showed good functional properties that could be used to develop functional food products.

Influence of thermal processing on flavor and sensory profile of sturgeon meat

Sensory analysis and instrumental techniques were used to investigate the effect of thermal processing on sturgeon meat flavor. A lexicon consisted of 26 descriptors was established for the sensory evaluation of raw and steamed sturgeon meat (4, 8, 12, 16, 20 min at 100 °C). Ten odor attributes generated by Check-all-that-apply and Free Choice Profiling methods were selected as characteristic descriptors, which were “fishy, meaty, oily/fatty, salty, umami, ammonia/rancid, grass, fresh, earthy, and visceral”. Aroma compounds were extracted by headspace-solid phase micro extraction (HS-SPME). A total of 63 and 62 volatiles were identified by gas chromatography equipped with mass spectrometry and olfactometry (GC-MS-O) and GC-ion mobility spectrometry (GC-IMS). Phospholipids accounted for 67.05% in 173 differential metabolites identified via untargeted metabolomics. 47 kinds of phosphatidylethanolamines were significantly correlated with the formation of aldehydes. This study provides a theoretical basis for regulating the flavor formation of thermal-processed aquatic products.

Influence of Thermal and Mechanical/Powder Processing on Microstructure and Dynamic Stiffness of Fe-Mn-Si-Cr-Ni Shape Memory Alloy

The influence of thermal processing and mechanical alloying of powder particles on the dynamic behavior and microstructural changes occurring in an Fel4Mn6Si9Cr5Ni (mass%) alloy is investigated. Five batches of 66Fe-14Mn-6Si-9Cr-5Ni (mass%) powder mixtures were produced via powder metallurgy. After powder mixing, different volume fractions (from 0 to 40 vol%) were mechanically alloyed, remixed with the rest of as-blended particles, compressed, sintered and subsequently hot rolled to a thickness of 1 mm. They were then subjected to a thermal treatment (annealing) at different temperatures and subsequently quenched into water. Thus, we had 25 different specimens for experimentation. The specimens were then machined and loaded in tension and subjected to dynamic mechanical analysis (DMA) by varying the temperature and strain amplitude. In the DMA tests, the samples were cycled between the ambient temperature and 673 K keeping the amplitude constant, while varying the temperature. These results were then correlated to the thermomagnetic properties that were measured in the same range of temperatures. Based on these data, the internal friction (tan δ) maxima, correlated with storage modulus (E′) discontinuities, were associated with the multistage reverse transformations of martensite (e, hcp) to austenite, superimposed over the antiferromagnetic–paramagnetic transitions and accompanied by magnetization peaks (Neel temperature). The temperature ranges pertaining to tan δ maxima, E′ discontinuities and magnetization peaks were determined and discussed in terms of thermal processing temperature and volume fraction of mechanically alloyed powder particles. The variation of storage modulus with strain for three different cycles (with strain amplitude varying from zero to maximum) was traced for three different temperatures: (i) T = RT; (ii) T Ttanδ (max). The role of magnitude of thermal treatment temperature and volume fraction of mechanically alloyed powder particles on the storage modulus plateaus were given prominence for these temperatures (RT, below tanδmax and above tanδmax) as they influence the evolution of the microstructure.

Influence of thermal processing on the characteristics and chemical profile of ora-pro-nobis by PS/MS paper spray

This work aimed to evaluate the influence of dry and wet heat processing on the antioxidant profile and antioxidant activity in ora-pro-nobis leaves. The leaves were collected, washed, and separated into three groups for the treatments: application of moist heat (hydrothermal cooking at 100 ºC / 4 minutes), application of dry heat (70 ºC / 8 hours), and control (raw material). The characteristics were evaluated: total soluble solids (SST), total solids (ST), pH, phenolic compounds (CPT), flavonoids (FT), anthocyanins (AT), antioxidant activity (AA). To identify the chemical profile and the chemical profile, fingerprints were obtained using PS / MS paper spray. The content of SST and ST decreased with moist heat. The CFT content increased with wet heat (12.43 ± 0.98) and decreased with dry heat (4.25 ± 0.93 g EAG 100 g-1). There was a decrease in the FT and AT content in the leaves processed with dry heat (132.67 ± 20.28 mg 100 g-1 and 19.70 ± 3.34 mg CG 100 g-1, respectively). AA decreased in both processes, which was higher in ora-pro-nobis leaves processed with dry heat (0.82 ± 0.0033 µmol ET g-1). 26 phenolic compounds were identified in the ora-pro-nob leaves by paper spray. The chemical profile, except for the substances 4,5-dimethyl-2,6-octadiene and methyl ester linolenic acid was not affected by thermal processing. Knowing the effect of food processing is important to understand the behavior of compounds that act beneficially on human health.

Influence of Thermal Processing on Resoloy Wire Microstructure and Properties

Magnesium fine wires are critical components for the fabrication of various absorbable implants. Herein, Resoloy fine wires with diameters of 200 and 500 μm are prepared with a multipass, cold‐drawing technique before undergoing two brief thermal anneals at 350 or 450 °C. The as‐drawn, cold‐worked (CW) wires show small but elongated α‐Mg grains, with their long axes and basal planes parallel to the drawing direction. Fine, continuous, and uniformly distributed Mg24Dy5 particles are observed within the wire. Although the brief anneals at 350 and 450 °C do not alter the texture of the Mg grains or the area fraction, aspect ratio, or distribution of the secondary phase, they do enable recovery and partial recrystallization at 350 °C and complete recrystallization at 450 °C, thereby providing a wide range of mechanical properties. The 200 μm wires display slightly higher strengths and slightly lower elongations. Modified simulated body fluid (m‐SBF) immersion results indicate that the Resoloy wires exhibit relatively uniform corrosion with rates as low as 1.72 ± 0.09, 1.44 ± 0.21, and 1.97 ± 0.10 mm y−1 for the cold‐worked, 350 °C, and 450 °C wires with 500 μm diameter, respectively.

Influence of Thermal Processing on Free and Bound Forms of Phenolics and Antioxidant Capacity of Rice Hull (Oryza sativa L.).

The objective of this study was to evaluate the effects of heat treatment on the phenolics and antioxidant activity of rice hull. Heat treatment was performed at temperatures 80∼140°C for 1∼5 h, and the heated rice hull was extracted with 80% (v/v) methanol in an ultrasonic bath. The highest total polyphenol and flavonoid content (10.68 mg gallic acid equivalents/g and 1.83 mg catechin equivalents/g, respectively) occurred in rice hull heated at 130°C for 5 h. During heat treatment, the content of free phenolic acids increased compared with that of the bound phenolic acids. The highest 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activity and reducing power was observed in rice hull heated at 140°C for 3 h. The highest OH radical scavenging activity was 75.30% in rice hull heated at 140°C for 5 h. These results suggested that heat treatment was an efficient method to enhance the antioxidant characteristics of rice hull.

Fe(Se,Te) from melting routes: the influence of thermal processing on microstructure and superconducting properties

Superconducting properties of the Fe(Se,Te) system are directly related to its microstructure. However, in the framework of a not well assessed phase diagram, a large spread of chemico-physical and functional properties is reported for compounds characterized by similar overall chemical compositions. This is in particular observed in materials produced by melting routes, where chemical inhomogeneities and multiple phases are commonly obtained. Both composition and morphology of these inhomogeneities seem to play a role in the behaviour of the superconducting phases, pointing out the need to assess the dependence of phase composition and therefore of the material performance on the sample thermal history.In this work, the effect of different post-synthesis annealing treatments is studied. A melting route has been adopted to synthesize polycrystalline samples, subsequently subjected to thermal treatments at different temperatures. Morphology and microstructure were characterized by means of x-ray diffraction and microscopy techniques. The superconducting properties have been evaluated by means of electrical and magnetic measurements. It is observed how microstructure, chemical composition and morphology of the obtained products strictly depend on the annealing temperature. Moreover, a crucial role of the cooling step is evidenced: in fact, a rapid cooling procedure from high temperature leads to the formation of high temperature (Tconset > 19 K) superconducting phases, but the overall bulk superconducting performance is negatively affected. Other annealing treatments can promote instead an enhancement in the critical current at high fields with respect to pristine sample, suggesting that a careful engineering of a post-synthesis thermal step can represent a useful tool to optimize the material properties.

Heat Treatment of Corrosion Resistant Steel for Water Propellers Fabricated by Direct Laser Deposition.

The urgency of heat treatment of samples of maraging steel obtained by direct laser deposition from steel powder 06Cr15Ni4CuMo is considered. The structural features and properties of 06Cr15Ni4CuMo steel samples after direct laser deposition and heat treatment are studied. The work is devoted to research into the influence of thermal processing on the formation of structure and the mechanical properties of deposit samples. Features of formation of microstructural components by means of optical microscopy are investigated. Tests for tension and impact toughness are conducted. As a result, it was established that the material obtained by the direct laser deposition method in its initial state significantly exceeds the strength characteristics of heat treatment castings of similar chemical composition, but is inferior to it in terms of impact toughness and relative elongation. The increase in relative elongation and impact toughness up to the level of cast material in the deposit samples is achieved at the subsequent heat treatment, which leads to the formation of the structure of tempered martensite and reduction in its content at two-stage tempering in the structure of the metal. The strength of the material is also reduced to the level of cast metal.

Influence of Thermal Processing on Oil Contents, Bioactive Properties of Melon Seed and Oils

The oil content and the fatty acid composition of roasted and unroasted melon seed and oils were determined. The oil contents of roasted melon seeds changed between 26.4% (Type 12) and 38.7% (Type 4). In general, oil contents of roasted melon seeds were found higher than that of unroasted seeds that could be due to the evaporation of water during roasting processes which consequently lead to increased concentrations of other seed components including oils. Saturated fatty acid contents of unroasted melon seed samples change between 13.5% (Type 6) and 17.1% (Type 20). In addition, polyunsaturated fatty acids of unroasted melon seed oils ranged from 51.9% (Type 13) to 70.2% (Type 6). Palmitic acid contents of roasted seed oils varied between 7.8% (Type 5) and 15.1% (Type 17). In addition, the oleic acid contents ranged from 15.4% (Type 10) to 37.7% (Type17). Also, linoleic acid contents were found between 34.7% (Type 17) and 70.3% (Type 6). Saturated fatty acid contents of roasted melon seed oils ranged from 13.5% (Type 6) to 16.7% (Type 13). The major tocopherols in both roasted and unroasted melon seed oils were α-tocopherol, ɣ-tocopherol and δ-tocopherols. Melon seed oils are rich in linoleic, oleic acids and ɣ-tocopherol.

The influence of thermal processing on the sorption of Cs and Sr by sitinakite

Abstract The remediation of radioactive isotopes such as Cs+ and Sr2+ from water has been evaluated using sitinakites. The sorption media employed in the remediation of radioactive wastes must have thermal and chemical stability to be useful. The present study investigates the structural stability and adsorption performance of sitinakites under conditions of elevated temperatures between 50 and 550 °C. X-ray diffraction indicates that major structural changes are initiated with heating, reducing the crystallinity of the material. The FTIR results also indicate that simultaneous and irreversible dehydration of the materials occurs with elevated temperatures under the conditions studied. Thermal processing also influences the sorption of Cs+, which decreases rapidly as the temperature increases. Adsorption was reduced by 80% at 550 °C for Cs+, when compared to the material processed at 50 °C and neutral pH. In contrast, the sorption of Sr2+ decreases substantially only when the processing temperature reaches 550 °C under the same conditions. In addition, the sorption of Cs+ and Sr2+ follow different trends as functions of pH after thermal treatment. The sorption of Cs+ decreases as a function of increased processing temperature and higher alkalinity. In contrast, the sorption of Sr2+ decreases with thermal processing; however, overall Sr2+ sorption increases as the pH becomes more alkaline. The sorption differences suggest that Cs+ uptake is structurally driven, while Sr2+ sorption is influenced by both the structure and the surface electrostatics of the material. These results suggest the effectiveness of the materials may be compromised due to changes in structure, hydration, and electrostatic interactions that occur when exposed to elevated temperatures.

The effect of thermal history on the atomic structure and mechanical properties of amorphous alloys

The influence of thermal processing on the potential energy, atomic structure, and mechanical properties of metallic glasses is examined using molecular dynamics simulations. We study the three-dimensional binary mixture, which was first relaxed near the glass transition temperature and zero pressure, and then rapidly cooled deep into the glass phase. It was found that glasses annealed at higher temperatures are relocated to higher energy states and their average glass structure remains more disordered, as reflected in the height of the first two peaks in the pair distribution function. The results of mechanical testing demonstrate that both the shear modulus and yielding peak increase significantly when the annealing temperature approaches Tg from above. Moreover, the shear modulus becomes a strong function of strain rate only for glasses relaxed at temperatures sufficiently higher than the glass transition temperature. Based on the spatial distribution of nonaffine displacements, we show that the deformation mode changes from brittle to ductile upon increasing annealing temperature. These results can be useful for the design and optimization of the fabrication processes of bulk glassy alloys with improved plasticity.

On the influence of thermal processes on the dynamics of a drill during deep hole machining

Deep drilling process has been studied and dynamic features of interaction the cutting part of the gun drill with the detail have been identified. Thermal processes of cutting and heat sinking in the interacting chains were analyzed: “heat source – workpiece”; “heat source - chips”; heat source – tool”; “heat source – cooling liquid”. It has been noted that the vibrations lead to the loss of dimensional accuracy of the part fabrication as well as hole surface quality. Mathematical dependence of the longitudinal and torsional oscillations of the cutting drill bit is determined and the influence of heat flow pulsations on the friction coefficients and cutting force is revealed.