BLR Size in Realistic FRADO Model: The Role of Shielding Effect

Fatigue crack propagation in near-threshold regime was studied in the 304L austenitic stainless steel in two microstructural states: as-received (AR) with finer microstructure and low susceptibility to the transformation-induced plasticity (TRIP) effect, and solution-annealed (SA) with coarser microstructure and higher susceptibility to TRIP. At the load ratio R = 0.1 the threshold was higher in the SA state than in the AR state due to coarser grains and possibly the TRIP effect. In order to clarify the role of crack closure, experiments at R = 0.7 were done. The threshold in the SA state was still higher by 1 MPa·m0.5. This effect was identified as crack tip shielding induced by phase transformation, an example of a non-closure shielding effect. Higher resistance to crack growth in the SA state was attributed to promoted martensitic transformation in non-favorable oriented grain families rather than thicker martensite layers in the crack path area. The conclusions were verified by experiments at R = 0.7 and temperature 150 °C > Ms which did not reveal any notable difference in thresholds. However, the threshold values were affected by the load-shedding gradient C = −dΔK/da, which had to be equalized in both experimental setups inside and outside the furnace.

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Tribological properties of experimental hard alloys in conditions of friction on structural steel without lubricant

MATEC Web of Conferences ◽

10.1051/matecconf/201822601006 ◽

2018 ◽

Vol 226 ◽

pp. 01006

Author(s):

Evgeniy V. Fominoff ◽

Constantine G. Shuchev ◽

Igor A. Khozyaev ◽

Yuriy A. Tsarev ◽

Viktor B. Rykov

Keyword(s):

Tribological Properties ◽

Base Alloy ◽

Shielding Effect ◽

Hard Alloys ◽

Friction Forces ◽

Friction Zone ◽

High Entropy ◽

Binding Phase ◽

Welding Bridges

Tribological properties of the experimental grades of high entropy hard alloys with modified binding phase on cobalt, which are characterized by minimal value of absolute t.m.f. to carbide phase, were experimentally investigated. It was established experimentally that new grades obtain better friction characteristics in comparison with the base alloy grade VK8 because friction processes of these materials in contact with structural steels are characterized by lower friction forces and lower temperatures in the friction zones. The ‘third body’ which is thicker than for the base alloy grade VK8, obtains a positive gradient of mechanical properties in friction zone, has a shielding effect, reduces the rate of generation of adhesive joints (welding bridges), and, perhaps, performs the role of dry lubrication.

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Nature of the interaction between rare gas atoms and transition metal doped silicon clusters: the role of shielding effects

Physical Chemistry Chemical Physics ◽

10.1039/c5cp00700c ◽

2015 ◽

Vol 17 (27) ◽

pp. 17584-17591 ◽

Cited By ~ 5

Author(s):

Vu Thi Ngan ◽

Ewald Janssens ◽

Pieterjan Claes ◽

André Fielicke ◽

Minh Tho Nguyen ◽

...

Keyword(s):

Density Functional ◽

Shielding Effect ◽

Rare Gas ◽

Silicon Clusters ◽

Doped Silicon ◽

Rare Gas Atoms ◽

Metal Doped ◽

Cu And Zn ◽

Shielding Effects

Density functional calculations and mass spectrometry reveal the role of a shielding effect from s-character electrons in the complexation between rare gas (Ar, Xe) and SinMn+ (n = 6–10), Si7TM+ (TM = Cr, Mn, Cu and Zn).

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VITAMIN-D LEVELS: NANO SOLDIERS AGAINST nCOVID-19 MEGA BATTLES

10.36106/ijar/6802190 ◽

2021 ◽

pp. 53-54

Author(s):

Neelam Das

Keyword(s):

Vitamin D ◽

Respiratory Infections ◽

Short Review ◽

Shielding Effect ◽

Magic Bullet ◽

Randomized Controlled ◽

The Past ◽

Vitamin D Levels ◽

Coronavirus Infection

Presently the world is battling a deadly pandemic without any effective licenced drugs or biologics to vanquish SARSCoV-2. The experience of managing the past viral aetiological outbreaks has been extrapolated to nCOVID-19, yet its effectiveness is uncertain. This connotation invokes a potential insight to focus upon those elements and etiquettes which are an integral part of our life and expound for nCOVID-19 treatment. This further impels us to consider our food as a time-tested medicine. In a study, a decrease in Vitamin-D levels accounted for the bovine coronavirus infection in calves. Interestingly it paves the way for exploring the role of Vitamin-D as an accessible 'magic bullet' against nCOVID-19. Currently, its metabolism and immunomodulatory characterization are well-established. In fact, the studies have described an inverse relationship between Vitamin-D level and respiratory infections. This further substantiates for understanding its shielding effect against nCOVID-19. Few researchers have recommended dosage of Vitamin-D intake among adult and highrisk individuals including front-liners. However, the enforcement of this potent nutritional ergogenic calls for dose rationalisation with due effectivity and safety based on large randomized controlled trials. This short review highlights the important scientic link between Vitamin D levels and susceptibility to COVID-19 in patients.

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Biological Legacies and Rockfall: The Protective Effect of a Windthrown Forest

Forests ◽

10.3390/f12091141 ◽

2021 ◽

Vol 12 (9) ◽

pp. 1141

Author(s):

Maximiliano Costa ◽

Niccolò Marchi ◽

Francesco Bettella ◽

Paola Bolzon ◽

Frédéric Berger ◽

...

Keyword(s):

Ecosystem Services ◽

Forest Management ◽

Management Practices ◽

Shielding Effect ◽

Mountain Forests ◽

Protective Function ◽

Salvage Logging ◽

Biological Legacies ◽

The Impact

Windstorms represent one of the main large-scale disturbances that shape the European landscape and influence its forest structure, so post-event restoration activities start to gain a major role in mountainous forest management. After a disturbance event, biological legacies may enhance or maintain multiple ecosystem services of mountain forests such as protection against natural hazards, biodiversity conservation, or erosion mitigation. However, the conservation of all these ecosystem services after stand-replacing events could go against traditional management practices, such as salvage logging. Thus far, the impact of salvage logging and removal of biological legacies on the protective function of mountain stands has been poorly studied. Structural biological legacies may provide protection for natural regeneration and may also increase the terrain roughness providing a shielding effect against gravitational hazards like rockfall. The aim of this project is to understand the dynamics of post-windthrow recovery processes and to investigate how biological legacies affect the multifunctionality of mountain forests, in particular the protective function. To observe the role of biological legacies we performed 3000 simulations of rockfall activity on windthrown areas. Results show the active role of biological legacies in preventing gravitational hazards, providing a barrier effect and an energy reduction effect on rockfall activity. To conclude, we underline how forest management should take into consideration the protective function of structural legacies. A suggestion is to avoid salvage logging in order to maintain the multifunctionality of damaged stands during the recovery process.

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ASSESSMENT OF THE INFLUENCE OF THE HEAT SHIELDING EFFECT OF OILS ON THE POSSIBILITY OF JAMMING IN THE MOBILE INTERFACES OF TRANSPORT VEHICLES

Actual directions of scientific researches of the XXI century theory and practice ◽

10.34220/2308-8877-2020-8-1-135-139 ◽

2020 ◽

Vol 8 (1) ◽

pp. 135-139

Author(s):

Dmitriy Popov ◽

M. Rudik ◽

A. Podzolkov

Keyword(s):

Theoretical Calculations ◽

Thermal Capacity ◽

Shielding Effect ◽

Material Density ◽

Mobile Interfaces ◽

Theoretical Assumptions ◽

Empirical Tests ◽

Heat Shielding ◽

Boundary Films

the influence of the heat-shielding effect of oils on the occurrence of wear in mobile interfaces during jamming, characterized by such a defect as a bully and accompanied by the transfer of metal from one friction surface to another, is analyzed. The research was carried out both on the basis of theoretical calculations based on the thermodynamic theory of friction, and empirical tests using the developed device for simulating a temperature flash on a stationary friction contact and subsequent observation of the propagation of the heat flow according to the indications of thermocouples. On the basis of theoretical assumptions, and the results of the research, the hypothesis that the heat energy released as the result of frictional interactions at microscopic contact, has a high density and is spread with considerable speed mainly in the direction with the lowest thermal resistance due to the thermophysical characteristics of the material (density, conductivity) and thermal capacity, for example, thin boundary films (oil, oxide, servovite, sputtered, etc.) with a thickness of 1 µm and is comparable with the height of asperities. The results of the research confirm the hypothesis about the role of the heat-shielding effect of lubricants on the microcontact overheating and changes in the structure and properties of both the lubricant and the metal surface layer, which in turn cause increased wear of machine parts.

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Natural disturbances and protective effect: the role of biological legacies in protection forests

10.5194/egusphere-egu21-12625 ◽

2021 ◽

Author(s):

Maximiliano Costa ◽

Niccolò Marchi ◽

Irene Trevisan ◽

Davide Marangon ◽

Emanuele Lingua

Keyword(s):

Ecosystem Services ◽

Natural Disturbance ◽

Shielding Effect ◽

Natural Disturbances ◽

Mountain Forests ◽

Protective Function ◽

Salvage Logging ◽

Biological Legacies ◽

The Impact

<p>Natural disturbance regimes are expected to be greatly altered in the next future byclimatechanges (e.g.increase in frequency and intensity, changing in seasonality). Among natural disturbances, windstorms represent one of the main large-scale factor that shape European landscape and that influence European forest structure. Moreover, windstorms may affect ecosystem services that are normally provided by mountain forests such as protection against natural hazards, conservation of biodiversity or erosion mitigation. However, after a disturbance event, structural biological legacies, like deadwood, may enhance or maintain some of these ecosystem services. After a stand-replacing event, the conservation or fast restoration of all these services should be the target of post disturbance management, but currently traditional practices (mainly salvage logging) are often leading to their depletion. The study of the impact of salvage logging (i.e. the removal of almost all the biological legacies) on the protective function of mountain stands has been poorly addressed. Structural biological legacies (i.e. snags, logs, stumps) may provide protection for the natural regeneration as well as they may increase the terrain roughness, providing a shielding effect against gravitative hazards like rockfall. The aim of the present study was to investigate how biological legacies affect the multifunctionality of mountain forests, focusing on the protective function. To observe the role of biological legacies we performed software simulations of rockfall activity on windthrown&#160;areas located in the Dolomites, region highly affected by the Vaia windstorm in October 2018. &#160;Results showed the short-term important role of biological legacies in mitigating rockfall propagation, mainly as barrier effect rather than an energy reduction effect. After a natural disturbance, forest management should take into consideration the residual protective function of structural legacies. Salvage logging operations should be limited in areas where rockfall hazard is high, in order to take advantage on the multifunctionality of biological legacies during the recovery process.</p>

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Influence of Sub-Debris Thawing on Ablation and Runoff of the Djankuat Glacier in the Caucasus

Hydrology Research ◽

10.2166/nh.2002.0005 ◽

2002 ◽

Vol 33 (1) ◽

pp. 75-94 ◽

Cited By ~ 31

Author(s):

Victor V. Popovnin ◽

Anastassia V. Rozova

Keyword(s):

Thermal Properties ◽

Mass Balance ◽

Ablation Rate ◽

Shielding Effect ◽

Glacier Surface ◽

The Caucasus ◽

Long Period ◽

Ice Surface ◽

Debris Cover

Superficial moraines grew in size during the entire 32-year-long period of direct monitoring of water and ice balance of the Djankuat Glacier in the Caucasus. The total area of debris cover on the glacier increased from 0.104 km2 (3% of the entire glacier surface) in 1968 to 0.266 km2 (8% of the glacier) in 1996. Such rapid dynamics of moraine formation greatly influences the ablation rate and distorts fields of mass-balance components. Sub-debris thawing can be calculated by means of a model, which describes the role of debris cover for the thermal properties of a glacier. Its meltwater equivalent depends mainly on debris thickness. In 1983 and 1994 the debris cover was repeatedly mapped over the whole glacier portion that was covered with morainic material. Sub-moraine ablation increases (vs. pure ice surface) under the thin, less than ca. 7-8 cm, debris layer, whereas the thicker debris cover reduces the liquid runoff due to its shielding effect. Zones differing due to their hydrological effect are depicted on the glacier map and the degree of debris influence on ablation is estimated quantitatively. As a whole runoff from debris-covered parts of the Djankuat Glacier has diminished due to the dominant shielding effect. Variation of the terminus is also shown to be dependent on the evolution of superficial moraine.

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Role of dactinomycin in the improved survival of children with Wilms' tumor

JAMA ◽

10.1001/jama.195.12.1005 ◽

1966 ◽

Vol 195 (12) ◽

pp. 1005-1009 ◽

Cited By ~ 18

Author(s):

D. J. Fernbach

Keyword(s):

Wilms Tumor

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