scholarly journals Dislocation–grain boundary interactions: recent advances on the underlying mechanisms studied via nanoindentation testing

2021 ◽  
Author(s):  
Farhan Javaid ◽  
Habib Pouriayevali ◽  
Karsten Durst
Keyword(s):  
Grain Boundary ◽  
Mechanical Response ◽  
Displacement Curve ◽  
Ambient Conditions ◽  
Recent Advances ◽  
Slip Transfer ◽  
Depth Analysis ◽  
Dislocation Interactions ◽  
Underlying Mechanisms ◽  
Insight Into

Abstract To comprehend the mechanical behavior of a polycrystalline material, an in-depth analysis of individual grain boundary (GB) and dislocation interactions is of prime importance. In the past decade, nanoindentation emerged as a powerful tool to study the local mechanical response in the vicinity of the GB. The improved instrumentation and test protocols allow to capture various GB–dislocation interactions during the nanoindentation in the form of strain bursts on the load–displacement curve. Moreover, the interaction of the plastic zone with the GB provides important insight into the dislocation transmission effects of distinct grain boundaries. Of great importance for the analysis and interpretation of the observed effects are microstructural investigations and computational approaches. This review paper focused on recent advances in the dislocation–GB interactions and underlying mechanisms studied via nanoindentation, which includes GB pop-in phenomenon, localized grain movement under ambient conditions, and an analysis of the slip transfer mechanism using theoretical treatments and simulations. Graphical abstract

scholarly journals Recent Advances in Enzyme-Nanostructure Biocatalysts with Enhanced Activity

Catalysts ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 338
Author(s):  
Jing An ◽  
Galong Li ◽  
Yifan Zhang ◽  
Tingbin Zhang ◽  
Xiaoli Liu ◽  
...  
Keyword(s):  
Metal Ion ◽  
High Efficiency ◽  
Practical Applications ◽  
Future Design ◽  
Recent Advances ◽  
Fundamental Research ◽  
Activity Enhancement ◽  
Underlying Mechanisms ◽  
Metal Ion Activation ◽  
Insight Into

Owing to their unique physicochemical properties and comparable size to biomacromolecules, functional nanostructures have served as powerful supports to construct enzyme-nanostructure biocatalysts (nanobiocatalysts). Of particular importance, recent years have witnessed the development of novel nanobiocatalysts with remarkably increased enzyme activities. This review provides a comprehensive description of recent advances in the field of nanobiocatalysts, with systematic elaboration of the underlying mechanisms of activity enhancement, including metal ion activation, electron transfer, morphology effects, mass transfer limitations, and conformation changes. The nanobiocatalysts highlighted here are expected to provide an insight into enzyme–nanostructure interaction, and provide a guideline for future design of high-efficiency nanobiocatalysts in both fundamental research and practical applications.

Nanoindentation study of slip transfer phenomenon at grain boundaries

2009 ◽  
Vol 24 (3) ◽  
pp. 607-615 ◽  
Author(s):  
T.B. Britton ◽  
D. Randman ◽  
A.J. Wilkinson
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Cold Work ◽  
Pure Copper ◽  
Displacement Curve ◽  
Interstitial Free ◽  
Face Centered Cubic ◽  
Slip Transfer ◽  
Individual Contributions ◽  
Face Centered

Nanoindentation was undertaken near grain boundaries to increase understanding of their individual contributions to the material’s macroscopic mechanical properties. Prior work with nanoindentation in body-centered cubic (bcc) materials has shown that some grain boundaries produce a “pop-in” event, an excursion in the load–displacement curve. In the current work, grain boundary associated pop-in events were observed in a Fe–0.01 wt% C polycrystal (bcc), and this is characteristic of high resistance to intergranular slip transfer. Grain boundaries with greater misalignment of slip systems tended to exhibit greater resistance to slip transfer. Grain boundary associated pop-ins were not observed in pure copper (face-centered cubic) or interstitial free steel ~0.002 wt% C (bcc). Additionally, it was found that cold work of the Fe–0.01 wt% C polycrystal immediately prior to indentation completely suppressed grain boundary associated pop-in events. It is concluded that the grain boundary associated pop-in events are directly linked to interstitials pinning dislocations on or near the boundary. This links well with macroscopic Hall–Petch effect observations.

Observations of dislocation interactions with recrystallized grain boundaries

1988 ◽  
Vol 46 ◽  
pp. 628-629
Author(s):  
C. W. Price
Keyword(s):  
Dislocation Density ◽  
Grain Boundary ◽  
Strain Rate ◽  
Grain Boundaries ◽  
Dislocation Structure ◽  
Hot Deformation ◽  
Static Recrystallization ◽  
High Dislocation Density ◽  
High Angle ◽  
Dislocation Interactions

Little evidence exists on the interaction of individual dislocations with recrystallized grain boundaries, primarily because of the severely overlapping contrast of the high dislocation density usually present during recrystallization. Interesting evidence of such interaction, Fig. 1, was discovered during examination of some old work on the hot deformation of Al-4.64 Cu. The specimen was deformed in a programmable thermomechanical instrument at 527 C and a strain rate of 25 cm/cm/s to a strain of 0.7. Static recrystallization occurred during a post anneal of 23 s also at 527 C. The figure shows evidence of dissociation of a subboundary at an intersection with a recrystallized high-angle grain boundary. At least one set of dislocations appears to be out of contrast in Fig. 1, and a grainboundary precipitate also is visible. Unfortunately, only subgrain sizes were of interest at the time the micrograph was recorded, and no attempt was made to analyze the dislocation structure.

Nucleosome dynamics

2006 ◽  
Vol 73 ◽  
pp. 109-119 ◽  
Author(s):  
Chris Stockdale ◽  
Michael Bruno ◽  
Helder Ferreira ◽  
Elisa Garcia-Wilson ◽  
Nicola Wiechens ◽  
...  
Keyword(s):  
High Resolution ◽  
Chromatin Structure ◽  
Current Knowledge ◽  
Dynamic Properties ◽  
Structure And Dynamics ◽  
Nucleosome Dynamics ◽  
Sharp Focus ◽  
Recent Advances ◽  
Insight Into ◽  
Chromatin Structure And Dynamics

In the 30 years since the discovery of the nucleosome, our picture of it has come into sharp focus. The recent high-resolution structures have provided a wealth of insight into the function of the nucleosome, but they are inherently static. Our current knowledge of how nucleosomes can be reconfigured dynamically is at a much earlier stage. Here, recent advances in the understanding of chromatin structure and dynamics are highlighted. The ways in which different modes of nucleosome reconfiguration are likely to influence each other are discussed, and some of the factors likely to regulate the dynamic properties of nucleosomes are considered.

scholarly journals Gut Microbiome and Metabolome Profiles Associated with High-Fat Diet in Mice

Metabolites ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 482
Author(s):  
Jae-Kwon Jo ◽  
Seung-Ho Seo ◽  
Seong-Eun Park ◽  
Hyun-Woo Kim ◽  
Eun-Ju Kim ◽  
...  
Keyword(s):  
Gut Microbiota ◽  
Relative Abundance ◽  
High Fat Diet ◽  
Amplicon Sequencing ◽  
Gas Chromatography Mass Spectrometry ◽  
Control Group ◽  
Rrna Gene ◽  
High Fat ◽  
Underlying Mechanisms ◽  
Insight Into

Obesity can be caused by microbes producing metabolites; it is thus important to determine the correlation between gut microbes and metabolites. This study aimed to identify gut microbiota-metabolomic signatures that change with a high-fat diet and understand the underlying mechanisms. To investigate the profiles of the gut microbiota and metabolites that changed after a 60% fat diet for 8 weeks, 16S rRNA gene amplicon sequencing and gas chromatography-mass spectrometry (GC-MS)-based metabolomic analyses were performed. Mice belonging to the HFD group showed a significant decrease in the relative abundance of Bacteroidetes but an increase in the relative abundance of Firmicutes compared to the control group. The relative abundance of Firmicutes, such as Lactococcus, Blautia, Lachnoclostridium, Oscillibacter, Ruminiclostridium, Harryflintia, Lactobacillus, Oscillospira, and Erysipelatoclostridium, was significantly higher in the HFD group than in the control group. The increased relative abundance of Firmicutes in the HFD group was positively correlated with fecal ribose, hypoxanthine, fructose, glycolic acid, ornithine, serum inositol, tyrosine, and glycine. Metabolic pathways affected by a high fat diet on serum were involved in aminoacyl-tRNA biosynthesis, glycine, serine and threonine metabolism, cysteine and methionine metabolism, glyoxylate and dicarboxylate metabolism, and phenylalanine, tyrosine, and trypto-phan biosynthesis. This study provides insight into the dysbiosis of gut microbiota and metabolites altered by HFD and may help to understand the mechanisms underlying obesity mediated by gut microbiota.

Recent Advances in Hydrogen Storage Materials

2012 ◽  
Vol 512-515 ◽  
pp. 1438-1441 ◽  
Author(s):  
Hong Min Kan ◽  
Ning Zhang ◽  
Xiao Yang Wang ◽  
Hong Sun
Keyword(s):  
Liquid Phase ◽  
Hydrogen Storage ◽  
Earth Metal ◽  
Solid Material ◽  
Hydrogen Energy ◽  
Hydrogen Storage Material ◽  
Ambient Conditions ◽  
Storage Material ◽  
Lithium Borohydride ◽  
Recent Advances

An overview of recent advances in hydrogen storage is presented in this review. The main focus is on metal hydrides, liquid-phase hydrogen storage material, alkaline earth metal NC/polymer composites and lithium borohydride ammoniate. Boron-nitrogen-based liquid-phase hydrogen storage material is a liquid under ambient conditions, air- and moisture-stable, recyclable and releases H2controllably and cleanly. It is not a solid material. It is easy storage and transport. The development of a liquid-phase hydrogen storage material has the potential to take advantage of the existing liquid-based distribution infrastructure. An air-stable composite material that consists of metallic Mg nanocrystals (NCs) in a gas-barrier polymer matrix that enables both the storage of a high density of hydrogen and rapid kinetics (loading in <30 min at 200°C). Moreover, nanostructuring of Mg provides rapid storage kinetics without using expensive heavy-metal catalysts. The Co-catalyzed lithium borohydride ammoniate, Li(NH3)4/3BH4 releases 17.8 wt% of hydrogen in the temperature range of 135 to 250 °C in a closed vessel. This is the maximum amount of dehydrogenation in all reports. These will reduce economy cost of the global transition from fossil fuels to hydrogen energy.

Gotta catch ‘em all: the microscale quest to understand cancer biology

2016 ◽  
Vol 8 (12) ◽  
pp. 1203-1207 ◽  
Author(s):  
Zhenwei Ma ◽  
Christopher Moraes
Keyword(s):  
Cancer Biology ◽  
Recent Advances ◽  
Cancer Initiation ◽  
Insight Into

We highlight recent advances in the innovative use of microscale engineered technologies to gain new insight into the integrative biophysical mechanisms that drive cancer initiation and progression.

Recent Advances and Perspective on Electrochemical Ammonia Synthesis under Ambient Conditions

Small Methods ◽  
2021 ◽  
pp. 2100460
Author(s):  
Yang Li ◽  
Qi Zhang ◽  
Zongwei Mei ◽  
Shunning Li ◽  
Wenbin Luo ◽  
...  
Keyword(s):  
Ammonia Synthesis ◽  
Ambient Conditions ◽  
Recent Advances

scholarly journals Discovery of Fe7O9: a new iron oxide with a complex monoclinic structure

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Ryosuke Sinmyo ◽  
Elena Bykova ◽  
Sergey V. Ovsyannikov ◽  
Catherine McCammon ◽  
Ilya Kupenko ◽  
...  
Keyword(s):  
Applied Sciences ◽  
Crystal Structure ◽  
Iron Oxide ◽  
Iron Oxides ◽  
Industrial Applications ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Pressure High Temperature ◽  
Insight Into

Abstract Iron oxides are fundamentally important compounds for basic and applied sciences as well as in numerous industrial applications. In this work we report the synthesis and investigation of a new binary iron oxide with the hitherto unknown stoichiometry of Fe7O9. This new oxide was synthesized at high-pressure high-temperature (HP-HT) conditions, and its black single crystals were successfully recovered at ambient conditions. By means of single crystal X-ray diffraction we determined that Fe7O9 adopts a monoclinic C2/m lattice with the most distorted crystal structure among the binary iron oxides known to date. The synthesis of Fe7O9 opens a new portal to exotic iron-rich (M,Fe)7O9 oxides with unusual stoichiometry and distorted crystal structures. Moreover, the crystal structure and phase relations of such new iron oxide groups may provide new insight into the cycling of volatiles in the Earth’s interior.

Nominal Number and Language Pathologies

2021 ◽  
pp. 290-304
Author(s):  
Britta Biedermann ◽  
Nora Fieder ◽  
Karen Smith-Lock
Keyword(s):  
Language Impairment ◽  
Language Production ◽  
Developmental Delays ◽  
Language Disorder ◽  
Number Processing ◽  
Developmental Language Disorder ◽  
Cognitive Neuropsychology ◽  
Underlying Mechanisms ◽  
Grammatical Number ◽  
Insight Into

This chapter provides an overview of the evidence on grammatical number processing taken from cognitive neuropsychology, including developmental delays and impairments of language (e.g. developmental language disorder, and Williams syndrome) and aphasia, an acquired language impairment after brain injury. These types of language impairment can give insight into the functional architecture of nominal number processing by looking at error patterns that arise in each of the aforementioned populations. By classifying observed responses in language production tasks into non-number and number errors, we are able to reveal underlying mechanisms of syntactic rules and their representations when they develop, but also learn about processes and representation of number when this information breaks down.

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