United States

ACCGE-22/OMVPE-20

Bulk Crystal Growth III

The recent years have seen a revolution in the science and practice of crystal growth. Novel mechanisms of nucleation and growth have decoded mysteries that have puzzled the community for ages. Elaborate processes and advanced techniques have birthed materials with unprecedented properties and exciting applications. Rationales developed within the crystal growth realm have illuminated longstanding conundrums in geology, biology, and medicine. 

These jointly-held conferences are the premier forums to discuss the huge modern advances in all aspects of crystal growth, both in the bulk and as epitaxial films. We will continue the tradition of numerous ACCGE and OMVPE meetings and bring together the topmost experts in the field from industry, academia, and government laboratories. Joining the two conferences affords an exceptional opportunity to present and discuss original results and provides a venue for newcomers to embrace the hot, new advances in science and technology. Our format is designed to maximize interaction among leading specialists and the wider crystal growth community, with oral and poster sessions as well as plenary and invited speakers to provide a broad picture of the up-to-date developments in the field.

Abstract book available to download [here.](https://drive.google.com/file/d/1TgUeguUw-f4cb_Pi14Fu_QjaOCObfsN-/view?usp=sharing) 

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technical paper

Alzheimer’s disease ranks as the third leading cause of death amongst adults over the age of 60 behind heart disease and cancer. The accumulation of amyloid plaque and neurofibrillary tangles causes the irreversible degradation and destruction of neurons that drastically shrinks brain tissue. Amyloid plaques are due to the buildup of insoluble amyloid beta (Aβ) fibrils formed from self-assembled propagation of peptides. Studies have shown that Aβ can take shape as soluble oligomers or insoluble fibrils with different morphologies. Aβ fibrils attain numerous structures, called polymorphs, both in patients’ brains and in vitro. Prior observations reveal that in agitated solutions the twofold polymorph of Aβ40 fibrils dominates, whereas the threefold polymorph of Aβ40 fibrils preferentially forms in the quiescent solutions. Previous atomic force microscopy (AFM) studies have demonstrated that the twofold symmetric Aβ40 polymorph grows steadily at broad ranges of peptide solution concentrations. It was also established that the fibril growth rate is determined by an activated complex, comprised by a peptide chain partially bound to the fibril tip and folded in a conformation distinct form that in the fibril bulk; the rearrangement of the intermediate configuration of the incoming peptide to the structure in the bulk fibril constitutes the transition state for growth [1]. We employ time-resolved in situ AFM to monitor the growth of seeds nucleated in quiescent solutions that belong to the threefold polymorph. We find that at low peptide concentrations, the fibrils growth bifurcates between two regimes. Growth either completely stalls or it proceeds at a rate, which is reproducible for the chosen solutions concentration. Similar observations of “stop and go” kinetics with other fibril-forming proteins have been attributed to two conformations of the soluble protein chains, growth complement, which supports growth, and growth incompetent, which caps the fibril tips and prevent association of growth competent chains. The recorded consistently steady growth of the two-fold Aβ40 fibrils, however, challenges the presence of growth-incompetent conformations in Aβ40 solutions. We put forth that stalled growth of the three-fold Aβ40 fibrils is due to an activated complex in which the incoming peptide folds into a conformation that cannot transform into the bulk fibril structure. The lifetime of that conformation of the activated complex defines the length of the period of stalled growth of the fibril. Our finding illuminates the complex interplay between fibril structures and the associated transition states during the growth of amyloid β fibrils.

BIFURCATED TRANSITION STATE FOR THE GROWTH OF THE THREEFOLD POLYMORPH OF AMYLOID BETA FIBRILS

III-V Epitaxial Growth for Devices I

Silicon Carbide and Gallium Oxide Materials and Devices I : Silicon Carbide 1

Narrow Bandgap Semiconductors and Devices

Biological and Biomimetic Materials II : Biomineralization 2

Characterization techniques for bulk and epitaxial crystallization II

Advanced Crystal Growth Technology and Equipment I

Ferroelectric Crystals and Textured Ceramics I : Relaxor-Based Piezocrystals & Applications

III-V Epitaxial Growth for Devices II

Advanced Crystal Growth Technology and Equipment II

https://d3smihljt9218e.cloudfront.net/transcript/21027/subtitle/6c4e5855ec9b4a11e8a7a188b159df41.vtt

English (automatic)

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BIFURCATED TRANSITION STATE FOR THE GROWTH OF THE THREEFOLD POLYMORPH OF AMYLOID BETA FIBRILS

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Next from ACCGE-22/OMVPE-20

BIFURCATED TRANSITION STATE FOR THE GROWTH OF THE THREEFOLD POLYMORPH OF AMYLOID BETA FIBRILS

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