Length scales and pinning of interfaces

The pinning of interfaces and free discontinuities by defects and heterogeneities plays an important role in a variety of phenomena, including grain growth, martensitic phase transitions, ferroelectricity, dislocations and fracture. We explore the role of length scale on the pinning of interfaces and show that the width of the interface relative to the length scale of the heterogeneity can have a profound effect on the pinning behaviour, and ultimately on hysteresis. When the heterogeneity is large, the pinning is strong and can lead to stick–slip behaviour as predicted by various models in the literature. However, when the heterogeneity is small, we find that the interface may not be pinned in a significant manner. This shows that a potential route to making materials with low hysteresis is to introduce heterogeneities at a length scale that is small compared with the width of the phase boundary. Finally, the intermediate setting where the length scale of the heterogeneity is comparable to that of the interface width is characterized by complex interactions, thereby giving rise to a non-monotone relationship between the relative heterogeneity size and the critical depinning stress.

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The role of Ni-Mn hybridization on the martensitic phase transitions in Mn-rich Heusler alloys

Applied Physics Letters ◽

10.1063/1.4705422 ◽

2012 ◽

Vol 100 (17) ◽

pp. 172403 ◽

Cited By ~ 46

Author(s):

Mahmud Khan ◽

J. Jung ◽

S. S. Stoyko ◽

Arthur Mar ◽

Abdiel Quetz ◽

...

Keyword(s):

Phase Transitions ◽

Heusler Alloys ◽

Martensitic Phase ◽

Martensitic Phase Transitions

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Surface Energy and Microstructure

MRS Proceedings ◽

10.1557/proc-246-19 ◽

1991 ◽

Vol 246 ◽

Author(s):

Robert V. Kohn ◽

Stefan MÜtller

Keyword(s):

Phase Transitions ◽

Energy Density ◽

Surface Energy ◽

Elastic Moduli ◽

Global Minimum ◽

Length Scale ◽

Surface Energy Density ◽

One Dimensional ◽

Martensitic Phase Transitions ◽

Bulk Energy

AbstractBulk energy considerations can predict the gross features of microstructures observed in martensitic phase transitions, but not finer details such as the length scale on which twinning occurs. These are determined by surface energy. A standard approach is to minimize the sum of bulk and surface energy within the class of “twinned” configurations. This leads to the conclusion that the twin width w and the twin length L should satisfy w ∼L∼. While that seems to be the rule, a different structure is sometimes observed, for example in In-Tl and Cu-Al-Ni. It involves successive coarsening of the twins away from an austenite/twinned-martensite interface.We re-examine the minimization of bulk plus surface energy. Our analysis differs from prior ones in that it permits configurations which are not essentially “onedimensional” to compete in the minimization. We find that the global minimum of energy can be either “one-dimensional” or “branched,” depending on the relative values of the elastic moduli and surface energy density.

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The role of the spinodal region in one-dimensional martensitic phase transitions

Physica D Nonlinear Phenomena ◽

10.1016/s0167-2789(97)00224-8 ◽

1998 ◽

Vol 115 (1-2) ◽

pp. 29-48 ◽

Cited By ~ 19

Author(s):

A. Vainchtein ◽

T. Healey ◽

P. Rosakis ◽

L. Truskinovsky

Keyword(s):

Phase Transitions ◽

Martensitic Phase ◽

One Dimensional ◽

Martensitic Phase Transitions ◽

Spinodal Region

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TEM Investigation Of Hydrogen-Induced Phase Transitions In Stainless Steel

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100118552 ◽

1985 ◽

Vol 43 ◽

pp. 336-337

Author(s):

E. Minkovitz ◽

D. Eliezer

Keyword(s):

Phase Transitions ◽

Martensite Phase ◽

Martensitic Phase ◽

Fracture Mechanisms ◽

Tem Analysis ◽

High Hydrogen ◽

Fine Grained ◽

Martensitic Phase Transitions ◽

316L Steel

The role of martensitic phase transitions in the embrittlement of stainless steels by hydrogen has been one of persistent controversial theme studied during recent years. The unresolved question, concerns the role of hydrogen in hydrogen induced phase transformation of the γ(fcc) austenite to α‘(bcc) and ɛ (hcp) martensite phases in the fracture mechanisms. The purpose of this study is to report the results of a TEM analysis of martensitic phase transitions under conditions of high hydrogen fugacities such as cathodic polarization in the absence of any externally applied stress.The results demonstrate the appearance of hydrogen induced ɛ-phase in 316L steel (Fig. 1(b)). No evidence of the appearance of α'-martensite phase after hydrogen charging was found within the grains, however, α'-martensite was found in front of the crack tip and along the crack surfaces as a very fine-grained polycrystalline structure (Fig. 1(c)).

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Complex interactions between precipitation, grain growth and recrystallization in a severely deformed Al-Zn-Mg-Cu alloy and consequences on the mechanical behavior

Materialia ◽

10.1016/j.mtla.2021.101028 ◽

2021 ◽

Vol 15 ◽

pp. 101028

Author(s):

Amandine Duchaussoy ◽

Xavier Sauvage ◽

Alexis Deschamps ◽

Frederic De Geuser ◽

Gilles Renou ◽

...

Keyword(s):

Mechanical Behavior ◽

Grain Growth ◽

Complex Interactions ◽

Cu Alloy

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Neuroimmune Response Mediated by Cytokines in Natural Scrapie after Chronic Dexamethasone Treatment

Biomolecules ◽

10.3390/biom11020204 ◽

2021 ◽

Vol 11 (2) ◽

pp. 204

Author(s):

Isabel M. Guijarro ◽

Moisés Garcés ◽

Pol Andrés-Benito ◽

Belén Marín ◽

Alicia Otero ◽

...

Keyword(s):

Prion Diseases ◽

Global Approach ◽

Profile Data ◽

Dexamethasone Treatment ◽

New Approach ◽

Complex Interactions ◽

Natural Scrapie ◽

Anti Inflammatory

The actual role of prion protein-induced glial activation and subsequent cytokine secretion during prion diseases is still incompletely understood. The overall aim of this study is to assess the effect of an anti-inflammatory treatment with dexamethasone on different cytokines released by neuroglial cells that are potentially related to neuroinflammation in natural scrapie. This study emphasizes the complex interactions existent among several pleiotropic neuromodulator peptides and provides a global approach to clarify neuroinflammatory processes in prion diseases. Additionally, an impairment of communication between microglial and astroglial populations mediated by cytokines, mainly IL-1, is suggested. The main novelty of this study is that it is the first one assessing in situ neuroinflammatory activity in relation to chronic anti-inflammatory therapy, gaining relevance because it is based on a natural model. The cytokine profile data would suggest the activation of some neurotoxicity-associated route. Consequently, targeting such a pathway might be a new approach to modify the damaging effects of neuroinflammation.

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Richness of Rhizosphere Organisms Affects Plant P Nutrition According to P Source and Mobility

Agriculture ◽

10.3390/agriculture11020157 ◽

2021 ◽

Vol 11 (2) ◽

pp. 157

Author(s):

Jean Trap ◽

Patricia Mahafaka Ranoarisoa ◽

Usman Irshad ◽

Claude Plassard

Keyword(s):

Careful Consideration ◽

Soil Conditions ◽

Organic P ◽

P Nutrition ◽

Soil P ◽

P Acquisition ◽

Complex Interactions ◽

Experimental Trials ◽

The Relationship

Plants evolve complex interactions with diverse soil mutualist organisms to enhance P mobilization from the soil. These strategies are particularly important when P is poorly available. It is still unclear how the soil P source (e.g., mineral P versus recalcitrant organic P) and its mobility in the soil (high or low) affect soil mutualist biological (ectomycorrhizal fungi, bacteria and bacterial-feeding nematodes) richness—plant P acquisition relationships. Using a set of six microcosm experiments conducted in growth chamber across contrasting P situations, we tested the hypothesis that the relationship between the increasing addition of soil mutualist organisms in the rhizosphere of the plant and plant P acquisition depends on P source and mobility. The highest correlation (R2 = 0.70) between plant P acquisition with soil rhizosphere biological richness was found in a high P-sorbing soil amended with an organic P source. In the five other situations, the relationships became significant either in soil conditions, with or without mineral P addition, or when the P source was supplied as organic P in the absence of soil, although with a low correlation coefficient (0.09 < R2 < 0.15). We thus encourage the systematic and careful consideration of the form and mobility of P in the experimental trials that aim to assess the role of biological complexity on plant P nutrition.

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Trace Elements as Immunoregulators in SARS-CoV-2 and Other Viral Infections

Indian Journal of Clinical Biochemistry ◽

10.1007/s12291-021-00961-6 ◽

2021 ◽

Author(s):

Karthick Dharmalingam ◽

Amandeep Birdi ◽

Sojit Tomo ◽

Karli Sreenivasulu ◽

Jaykaran Charan ◽

...

Keyword(s):

Immune Response ◽

Trace Elements ◽

Viral Entry ◽

Viral Infections ◽

Inhibitory Effect ◽

Antioxidants Activity ◽

Host Immune Responses ◽

Complex Interactions ◽

Downstream Processes

AbstractNutritional deficiency is associated with impaired immunity and increased susceptibility to infections. The complex interactions of trace elements with the macromolecules trigger the effective immune response against the viral diseases. The outcome of various viral infections along with susceptibility is affected by trace elements such as zinc, selenium, iron, copper, etc. due to their immuno-modulatory effects. Available electronic databases have been comprehensively searched for articles published with full text available and with the key words “Trace elements”, “COVID-19”, “Viral Infections” and “Immune Response” (i.e. separately Zn, Se, Fe, Cu, Mn, Mo, Cr, Li, Ni, Co) appearing in the title and abstract. On the basis of available articles we have explored the role of trace elements in viral infections with special reference to COVID-19 and their interactions with the immune system. Zinc, selenium and other trace elements are vital to triggerTH1 cells and cytokine-mediated immune response for substantial production of proinflammatory cytokines. The antiviral activity of some trace elements is attributed to their inhibitory effect on viral entry, replication and other downstream processes. Trace elements having antioxidants activity not only regulate host immune responses, but also modify the viral genome. Adequate dietary intake of trace elements is essential for activation, development, differentiation and numerous functions.

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