STRUCTURAL FEATURES OF DAMAGES ACCUMULATION IN CONDITIONS OF COMBINED CYCLIC LOADING

2019 ◽  
Vol 85 (5) ◽  
pp. 46-51 ◽  
Author(s):  
L. L. Smirnova ◽  
A. V. Zinin
Keyword(s):  
Elastoplastic Deformation ◽  
Structural Changes ◽  
Experimental Studies ◽  
Fatigue Loading ◽  
Structural Features ◽  
Subsequent Stage ◽  
Preliminary Loading ◽  
Second Stage ◽  
Fatigue Durability ◽  
Damage To The Material

A significant part of the elements of machines and structures along with stationary fatigue is subjected to combined impacts of low-cycle and multi-cycle fatigue loading in operation. The physical nature of their fracture in these conditions depends on the ratio of the mode parameters and entails the necessity of advanced research. The predominance of this or that process determines the nature of the damage accumulation which leads to the destruction. Under such conditions, i.e., preliminary cyclic elastoplastic deformation followed by subsequent fatigue loading, the material subjected to preliminary loading at the first stage can be considered the "new material" with the new properties acquired upon cyclic elastoplastic loading which then undergoes further fatigue loading at the second stage. Hence, at the second stage, the new properties of the material are determined by the level of structural changes and damages earlier accumulated in the material. In this case, the damage to the material is considered on the basis of the well-known statement about the staging character of plastic flow, two main processes, i.e., shear, caused by the interaction of dislocations, and destructuring, attributed to violation of the continuity or integrity of the metal. Experimental studies of changes in the durability of cyclically hardened and cyclically softened steel specimens at different levels of preliminary elastoplastic deformation with varying number of cycles and amplitudes of preliminary elastoplastic strain showed the occurrence of an additional damage to the material when combination of loading modes leads to change in the fatigue durability at the subsequent stage of the basic multi-cycle loading. It is shown that correlation between changes in the fatigue durability and structural state of the material, caused by accumulated damage upon preliminary overloads, and, moreover, those changes can be characterized by the ratio of plastic and destructive strains as a Q-factor of the material.

Analysis of the results of medium-energy electrons on the protective and thermoregulatory coatings of high-orbit satellites

2018 ◽  
pp. 156-171
Author(s):  
A. M. Shamayev ◽  
M. D. Ozersky
Keyword(s):  
Structural Changes ◽  
Protective Coatings ◽  
Experimental Studies ◽  
Thermal Control ◽  
Space Vehicles ◽  
Medium Energy ◽  
Electrostatic Discharges ◽  
High Orbit ◽  
Thermal Control Coatings ◽  
Solar Batteries

The results of experimental studies of the effect of electron irradiation on K-208 and CMG glasses used for manufacturing protective coatings of solar batteries and thermal control coatings of space vehicles are analyzed. It is shown that the caused electrostatic discharges lead to structural changes in the surfaces of the glasses studied. The goals of further studies of the influence of proton and electronproton effects on the properties of such coatings are outlined. 

scholarly journals Interaction of Lactoferrin with Unsaturated Fatty Acids: In Vitro and In Vivo Study of Human Lactoferrin/Oleic Acid Complex Cytotoxicity

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1602
Author(s):  
Anna Elizarova ◽  
Alexey Sokolov ◽  
Valeria Kostevich ◽  
Ekaterina Kisseleva ◽  
Evgeny Zelenskiy ◽  
...  
Keyword(s):  
Oleic Acid ◽  
Structural Changes ◽  
Unsaturated Fatty Acids ◽  
Structural Features ◽  
Control Group ◽  
Acid Complex ◽  
Hepatoma 22A ◽  
Constitutive Parameters

As shown recently, oleic acid (OA) in complex with lactoferrin (LF) causes the death of cancer cells, but no mechanism(s) of that toxicity have been disclosed. In this study, constitutive parameters of the antitumor effect of LF/OA complex were explored. Complex LF/OA was prepared by titrating recombinant human LF with OA. Spectral analysis was used to assess possible structural changes of LF within its complex with OA. Structural features of apo-LF did not change within the complex LF:OA = 1:8, which was toxic for hepatoma 22a cells. Cytotoxicity of the complex LF:OA = 1:8 was tested in cultured hepatoma 22a cells and in fresh erythrocytes. Its anticancer activity was tested in mice carrying hepatoma 22a. In mice injected daily with LF-8OA, the same tumor grew significantly slower. In 20% of animals, the tumors completely resolved. LF alone was less efficient, i.e., the tumor growth index was 0.14 for LF-8OA and 0.63 for LF as compared with 1.0 in the control animals. The results of testing from 48 days after the tumor inoculation showed that the survival rate among LF-8OA-treated animals was 70%, contrary to 0% rate in the control group and among the LF-treated mice. Our data allow us to regard the complex of LF and OA as a promising tool for cancer treatment.

scholarly journals Post-operative rehabilitation and nutrition in osteoarthritis

F1000Research ◽  
2016 ◽  
Vol 3 ◽  
pp. 116 ◽  
Author(s):  
Giuseppe Musumeci ◽  
Ali Mobasheri ◽  
Francesca Maria Trovato ◽  
Marta Anna Szychlinska ◽  
Rosa Imbesi ◽  
...  
Keyword(s):  
Articular Cartilage ◽  
Physical Exercise ◽  
Structural Changes ◽  
Exercise Program ◽  
Structural Features ◽  
Synovial Joint ◽  
Comprehensive Overview ◽  
Postoperative Rehabilitation ◽  
Keywords Osteoarthritis ◽  
Rehabilitation Exercise

Osteoarthritis (OA) is a degenerative process involving the progressive loss of articular cartilage, synovial inflammation and structural changes in subchondral bone that lead to loss of synovial joint structural features and functionality of articular cartilage. OA represents one of the most common causes of physical disability in the world. Different OA treatments are usually considered in relation to the stage of the disease. In the early stages, it is possible to recommend physical activity programs that can maintain joint health and keep the patient mobile, as recommended by OA Research Society International (OARSI) and European League Against Rheumatism (EULAR). In the most severe and advanced cases of OA, surgical intervention is necessary. After, in early postoperative stages, it is essential to include a rehabilitation exercise program in order to restore the full function of the involved joint. Physical therapy is crucial for the success of any surgical procedure and can promote recovery of muscle strength, range of motion, coordinated walking, proprioception and mitigate joint pain. Furthermore, after discharge from the hospital, patients should continue the rehabilitation exercise program at home associated to an appropriate diet. In this review, we analyze manuscripts from the most recent literature and provide a balanced and comprehensive overview of the latest developments on the effect of physical exercise on postoperative rehabilitation in OA. The literature search was conducted using PubMed, Scopus, Web of Science and Google Scholar, using the keywords ‘osteoarthritis’, ‘rehabilitation’, ‘exercise’ and ‘nutrition’. The available data suggest that physical exercise is an effective, economical and accessible to everyone practice, and it is one of the most important components of postoperative rehabilitation for OA.

Cascade control of «smart home» heating

2022 ◽  
Vol 14 (4) ◽  
pp. 82-89
Author(s):  
Sergey Polyakov ◽  
V. Akimov ◽  
A. Polukazakov
Keyword(s):  
Structural Changes ◽  
Experimental Studies ◽  
Residential Building ◽  
Heating System ◽  
Cascade Control ◽  
Virtual Object ◽  
Coolant Temperature ◽  
Home Heating ◽  
Input Signals ◽  
Selection Of

The article discusses the issues of implementing the conversion of input signals of «smart» sensors for automation of the heating system, an algorithm for calculating the parameters of measuring circuits with a nonlinear element and an operational amplifier is developed. The issues of modeling cascade control of residential building heating systems are investigated. The results of the analysis and selection of parameters of the cascade control system are presented. An algorithm implementing the operation of a virtual object is given. The structures of management of residential building objects are proposed. The method of calculating the adjustment of the controller for cascade control is given. For the heating system stand, the procedure for setting the parameters of the process of PID control of the coolant temperature is considered. The results confirming the achievability of the proposed structural changes are obtained. The results of experimental studies are presented.

SOFTWARE FOR CONTROL SYSTEMS FOR «SMART» RESIDENTIAL BUILDING

2021 ◽  
Vol 14 (1) ◽  
pp. 58-67
Author(s):  
Sergey Polyakov ◽  
V. Akimov ◽  
A. Polukazakov ◽  
Vladimir Zolnikov ◽  
P. Enin
Keyword(s):  
Structural Changes ◽  
Life Support ◽  
Assembly Language ◽  
Experimental Studies ◽  
Residential Building ◽  
Heating System ◽  
Liquid Level ◽  
Virtual Object ◽  
Level Control ◽  
The Relationship

The article deals with the issues of modeling and management of life support systems of a residential building. The resulting model of the liquid level in the tank allows you to establish the relationship between the level and the flow rate of the liquid. The results of the selection and justification of the fluid level control structure are presented. An algorithm that implements the operation of a virtual object is given. The structure of the automatic control system (ACS) of the liquid level is technically implemented in an open type. The results confirming the achievability of the proposed structural changes are obtained. The results of experimental studies are presented. The choice and justification of the method of controlling the heating system and the liquid level in the tank are considered. Programs for managing subsystems of a residential building in Assembly language, C++, and ladder diagrams are presented. A model for controlling the liquid level in a Multisim environment is proposed.

Structural deformation-metamorphism and exhumation processes of Yuanmou metamorphic complex, Yunnan, China

2021 ◽  
Author(s):  
Xuemei Cheng ◽  
Shuyun Cao
Keyword(s):  
High Temperature ◽  
Electron Backscatter Diffraction ◽  
Early Stage ◽  
Structural Features ◽  
Detachment Fault ◽  
Ductile Deformation ◽  
Structural Deformation ◽  
Subsequent Stage ◽  
Metamorphic Complex ◽  
South Central

<p>Within orogenic zone and continental extensional area, it often developed metamorphic complex or metamorphic gneiss dome that widely exposed continental mid-lower crustal rocks, which is an ideal place to study exhumation processes of deep-seated metamorphic complex and rheology. The Yuanmou metamorphic complex is located in the south-central part of the "Kangdian Axis" in the western margin of Qiangtang Block and Yangtze Block, which is a part of the anticline of the Sichuan-Yunnan platform. Many research works mainly focus on the discussion of intrusion ages, aeromagnetic anomalies, and polymetallic deposits. However, the exhumation process and mechanism of the Yuanmou metamorphic complex are rarely discussed and still unclear. This study, based on detailed field geological observations, optical microscopy (OM), cathodoluminescence (CL), electron backscatter diffraction (EBSD) and electron probe (EMPA) were performed to illustrate the geological structure features, deformation-metamorphic evolution process and its tectonic significance of Yuanmou metamorphic complex during the exhumation process. All these analysis results indicate that the Yuanmou metamorphic complex generally exhibits a dome structure with deep metamorphic rocks and deformed rocks of varying degrees widely developed. Mylonitic gneiss and granitic intrusions are located in the footwall of the Yuanmou, which have suffered high-temperature shearing. The mylonitic fabrics and mineral stretching lineations in the deformed rock are strongly developed, forming typical S-L or L-shaped structural features. The high-temperature ductile deformation-metamorphism environment is high amphibolite facies, that is, the temperature range is between 620 ~ 690 ℃ and the pressure is between 0.8 ~ 0.95 Gpa. In the deformed rocks closed to the detachment fault, some of the mylonite fabric features are retained, but most of them have experienced a strongly overprinted retrogression metamorphism and deformation. At the top of the detachment fault zone, it is mainly composed of cataclasites and fault gouge. The comprehensive macro- and microstructural characteristics, geometry, kinematics, and mineral (amphibole, quartz and calcite) EBSD textures indicate that the Yuanmou metamorphic complex has undergone a progressive exhumation process during regional extension, obvious high-temperature plastic deformation-metamorphism in the early stage, and superimposed of low-temperature plastic-brittle and brittle deformation in the subsequent stage, which is also accompanied by strong fluid activities during the exhumation process.</p>

Experimental Studies of Fiber-Reinforced Concrete under Axial Tension

2021 ◽  
Vol 1038 ◽  
pp. 323-329
Author(s):  
Zlata Holovata ◽  
Daria Kirichenko ◽  
Irina Korneeva ◽  
Stepan Neutov ◽  
Marina Vyhnanets
Keyword(s):  
Reinforced Concrete ◽  
Experimental Studies ◽  
Fiber Reinforced Concrete ◽  
Load Application ◽  
Fiber Reinforced ◽  
Large Aggregate ◽  
Second Stage ◽  
Axial Tension ◽  
Deformation Properties ◽  
Fiber Concrete

The design of a stand for testing concrete and fiber-reinforced concrete specimens-"eight" in tension, which provides axial load application and minimizes the effect of stress concentration at the ends of the specimen. The design of the stand is such that the distance between the axis of load application and the central hinge is 108 cm, and between this hinge and the axis of the test specimen is 21 cm, as a result of which the load transferred to the specimen is 5.143 times greater than the applied one. At the first stage of testing, it was found that the optimal characteristics of the fiber-concrete mixture is a matrix with a large aggregate ≤ 10 mm with 1.0% fiber reinforcement. At the second stage, the ultimate strength of fiber-reinforced concrete for axial tension was determined - 1.28 MPa when reinforced with wave fiber and 1.37 MPa when reinforced with anchor fiber, which amounted to 4.1% and 4.4% of compressive strength, respectively. It was also found that concrete reinforced with anchor fiber has higher deformation properties than concrete reinforced with wave fiber.

Recent insights into lytic polysaccharide monooxygenases (LPMOs)

2018 ◽  
Vol 46 (6) ◽  
pp. 1431-1447 ◽  
Author(s):  
Tobias Tandrup ◽  
Kristian E. H. Frandsen ◽  
Katja S. Johansen ◽  
Jean-Guy Berrin ◽  
Leila Lo Leggio
Keyword(s):  
Active Site ◽  
Room Temperature ◽  
Experimental Studies ◽  
Binding Mode ◽  
Structural Features ◽  
Oxygen Species ◽  
Animal Kingdom ◽  
X Ray ◽  
Lytic Polysaccharide Monooxygenases ◽  
Polysaccharide Monooxygenases

Lytic polysaccharide monooxygenases (LPMOs) are copper enzymes discovered within the last 10 years. By degrading recalcitrant substrates oxidatively, these enzymes are major contributors to the recycling of carbon in nature and are being used in the biorefinery industry. Recently, two new families of LPMOs have been defined and structurally characterized, AA14 and AA15, sharing many of previously found structural features. However, unlike most LPMOs to date, AA14 degrades xylan in the context of complex substrates, while AA15 is particularly interesting because they expand the presence of LPMOs from the predominantly microbial to the animal kingdom. The first two neutron crystallography structures have been determined, which, together with high-resolution room temperature X-ray structures, have putatively identified oxygen species at or near the active site of LPMOs. Many recent computational and experimental studies have also investigated the mechanism of action and substrate-binding mode of LPMOs. Perhaps, the most significant recent advance is the increasing structural and biochemical evidence, suggesting that LPMOs follow different mechanistic pathways with different substrates, co-substrates and reductants, by behaving as monooxygenases or peroxygenases with molecular oxygen or hydrogen peroxide as a co-substrate, respectively.

scholarly journals Century-Long Dynamics of the Land Use Structure in the United States

2020 ◽  
pp. 220-231
Author(s):  
Valerij Minat
Keyword(s):  
United States ◽  
Land Use ◽  
Structural Changes ◽  
The United States ◽  
Structural Features ◽  
Summary Table ◽  
Land Use Structure ◽  
Periodic Dynamics ◽  
Space Dynamics ◽  
American Society

The paper studies the experience of American land use in the twentieth century on the territory of 48 contiguous continental states. Changes in time and space (dynamics) of the main indicators of distribution and use of land resources that form the structural appearance of the U.S. land fund are shown. Based on the analysis of the countrys land use structure, the resulting part of which is a summary table, the periodic dynamics of the land use structure (in twenty-year time intervals) is considered, and the dependence of structural changes in land use on the level and nature of the socio-economic development of American society is shown. The study of the age-old dynamics of structural features of American land use conducted on the basis of scientific materials of American scientists and data from official American statistics makes it possible to draw generalizing conclusions about the nature of land use in the United States, both in the whole country and in the regional aspect. As a result, the author has obtained a generalized scientific picture of how the structure of land use in the continental part of the country (without Alaska) has changed over the course of a century in the direction from maximum to optimal use of natural resources.

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