The Dynamic Basis of Structural Order in Proteins

2022 ◽  
Author(s):  
Chilaluck Konkankit ◽  
S. Rackovsky
Keyword(s):  
Structural Order

Elemental mass loss in silicate minerals during x-ray analysis

1990 ◽  
Vol 48 (4) ◽  
pp. 804-805
Author(s):  
P.E. Champness ◽  
R.W. Devenish
Keyword(s):  
Mass Loss ◽  
Current Density ◽  
Damage Mechanism ◽  
Beam Current ◽  
Single Chain ◽  
Plagioclase Feldspar ◽  
X Ray ◽  
Alkali Ions ◽  
Structural Order ◽  
Sheet Silicate

It has long been recognised that silicates can suffer extensive beam damage in electron-beam instruments. The predominant damage mechanism is radiolysis. For instance, damage in quartz, SiO2, results in loss of structural order without mass loss whereas feldspars (framework silicates containing Ca, Na, K) suffer loss of structural order with accompanying mass loss. In the latter case, the alkali ions, particularly Na, are found to migrate away from the area of the beam. The aim of the present study was to investigate the loss of various elements from the common silicate structures during electron irradiation at 100 kV over a range of current densities of 104 - 109 A m−2. (The current density is defined in terms of 50% of total current in the FWHM probe). The silicates so far ivestigated are:- olivine [(Mg, Fe)SiO4], a structure that has isolated Si-O tetrahedra, garnet [(Mg, Ca, Fe)3Al2Si3AO12 another silicate with isolated tetrahedra, pyroxene [-Ca(Mg, Fe)Si2O6 a single-chain silicate; mica [margarite, -Ca2Al4Si4Al4O2O(OH)4], a sheet silicate, and plagioclase feldspar [-NaCaAl3Si5O16]. Ion- thinned samples of each mineral were examined in a VG Microscopes UHV HB501 field- emission STEM. The beam current used was typically - 0.5 nA and the current density was varied by defocussing the electron probe. Energy-dispersive X-ray spectra were collected every 10 seconds for a total of 200 seconds using a Link Systems windowless detector. The thickness of the samples in the area of analysis was normally 50-150 nm.

scholarly journals Structural Order of the Molecular Adlayer Impacts the Stability of Nanoparticle-on-Mirror Plasmonic Cavities

ACS Photonics ◽  
2021 ◽  
Author(s):  
Aqeel Ahmed ◽  
Karla Banjac ◽  
Sachin S. Verlekar ◽  
Fernando P. Cometto ◽  
Magalí Lingenfelder ◽  
...  
Keyword(s):  
Structural Order ◽  
The Stability

scholarly journals Structural disorder of graphite and implications for graphite thermometry

Solid Earth ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 223-231 ◽  
Author(s):  
Martina Kirilova ◽  
Virginia Toy ◽  
Jeremy S. Rooney ◽  
Carolina Giorgetti ◽  
Keith C. Gordon ◽  
...  
Keyword(s):  
Irreversible Process ◽  
Carbonaceous Material ◽  
Graphite Powder ◽  
Structural Disorder ◽  
Structural Order ◽  
Active Tectonic ◽  
Graphite Structure ◽  
Tectonic Settings ◽  
Host Rocks ◽  
Crystalline Graphite

Abstract. Graphitization, or the progressive maturation of carbonaceous material, is considered an irreversible process. Thus, the degree of graphite crystallinity, or its structural order, has been calibrated as an indicator of the peak metamorphic temperatures experienced by the host rocks. However, discrepancies between temperatures indicated by graphite crystallinity versus other thermometers have been documented in deformed rocks. To examine the possibility of mechanical modifications of graphite structure and the potential impacts on graphite thermometry, we performed laboratory deformation experiments. We sheared highly crystalline graphite powder at normal stresses of 5 and 25  megapascal (MPa) and aseismic velocities of 1, 10 and 100 µm s−1. The degree of structural order both in the starting and resulting materials was analyzed by Raman microspectroscopy. Our results demonstrate structural disorder of graphite, manifested as changes in the Raman spectra. Microstructural observations show that brittle processes caused the documented mechanical modifications of the aggregate graphite crystallinity. We conclude that the calibrated graphite thermometer is ambiguous in active tectonic settings.

scholarly journals Detection of nitroaromatic vapours with diketopyrrolopyrrole thin films: exploring the role of structural order and morphology on thin film properties and fluorescence quenching efficiency

2015 ◽  
Vol 51 (6) ◽  
pp. 1143-1146 ◽  
Author(s):  
Monika Warzecha ◽  
Jesus Calvo-Castro ◽  
Alan R. Kennedy ◽  
Alisdair N. Macpherson ◽  
Kenneth Shankland ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Fluorescence Quenching ◽  
Optical Detection ◽  
Film Properties ◽  
Structural Order ◽  
Quenching Efficiency ◽  
First Time

Sensitive optical detection of nitroaromatic vapours with diketopyrrolopyrrole thin films is reported for the first time.

Local structural order in carbonic acid polymorphs: Raman and FT-IR spectroscopy

2011 ◽  
Vol 43 (1) ◽  
pp. 108-115 ◽  
Author(s):  
Christian Mitterdorfer ◽  
Jürgen Bernard ◽  
Frederik Klauser ◽  
Katrin Winkel ◽  
Ingrid Kohl ◽  
...  
Keyword(s):  
Ir Spectroscopy ◽  
Carbonic Acid ◽  
Structural Order ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

Structural order in alkali-degraded PAN as seen in studies of low-temperature thermal conductivity

Polymer ◽  
1983 ◽  
Vol 24 (3) ◽  
pp. 258-262 ◽  
Author(s):  
N.S. Batty ◽  
A.J. Gradwell ◽  
J.T. Guthrie ◽  
D. Greig ◽  
N.D. Hardy ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Low Temperature ◽  
Structural Order

Raman studies of structural order in amorphous silicon-boron alloys

1989 ◽  
Vol 72 (2) ◽  
pp. 159-161 ◽  
Author(s):  
G. Yang ◽  
P. Bai ◽  
B.Y. Tong ◽  
S.K. Wong ◽  
I. Hill
Keyword(s):  
Amorphous Silicon ◽  
Structural Order
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