pH-dependent structural changes of arsenic oxoacids in solution and solid phase: Raman spectrometry and computational studies

2021 ◽  
pp. 107109
Author(s):  
F.J. Pereira ◽  
R. López ◽  
D. Suarez ◽  
A.J. Aller
Keyword(s):  
Structural Changes ◽  
Solid Phase ◽  
Computational Studies ◽  
Raman Spectrometry ◽  
Ph Dependent

scholarly journals Cofilin is a pH sensor for actin free barbed end formation: role of phosphoinositide binding

2008 ◽  
Vol 183 (5) ◽  
pp. 865-879 ◽  
Author(s):  
Christian Frantz ◽  
Gabriela Barreiro ◽  
Laura Dominguez ◽  
Xiaoming Chen ◽  
Robert Eddy ◽  
...  
Keyword(s):  
Actin Filament ◽  
Structural Changes ◽  
Ph Sensor ◽  
Ph Sensitive ◽  
Actin Binding ◽  
Filamentous Actin ◽  
Filament Dynamics ◽  
Ph Dependent ◽  
Dynamics Simulations

Newly generated actin free barbed ends at the front of motile cells provide sites for actin filament assembly driving membrane protrusion. Growth factors induce a rapid biphasic increase in actin free barbed ends, and we found both phases absent in fibroblasts lacking H+ efflux by the Na-H exchanger NHE1. The first phase is restored by expression of mutant cofilin-H133A but not unphosphorylated cofilin-S3A. Constant pH molecular dynamics simulations and nuclear magnetic resonance (NMR) reveal pH-sensitive structural changes in the cofilin C-terminal filamentous actin binding site dependent on His133. However, cofilin-H133A retains pH-sensitive changes in NMR spectra and severing activity in vitro, which suggests that it has a more complex behavior in cells. Cofilin activity is inhibited by phosphoinositide binding, and we found that phosphoinositide binding is pH-dependent for wild-type cofilin, with decreased binding at a higher pH. In contrast, phosphoinositide binding by cofilin-H133A is attenuated and pH insensitive. These data suggest a molecular mechanism whereby cofilin acts as a pH sensor to mediate a pH-dependent actin filament dynamics.

Modification of Barium Cerate by Heavy Ion Irradiation

2013 ◽  
Vol 781-784 ◽  
pp. 357-361 ◽  
Author(s):  
Igor V. Khromushin ◽  
Taтiana I. Aksenova ◽  
Turgora Tuseyev ◽  
Karlygash K. Munasbaeva ◽  
Yuri V. Ermolaev ◽  
...  
Keyword(s):  
Structural Changes ◽  
Solid Phase ◽  
Ion Irradiation ◽  
Heavy Ion ◽  
High Energy ◽  
Low Energy ◽  
Barium Cerate ◽  
Weakly Bound ◽  
Ion Ranges ◽  
High Energy Ions

The effect of irradiation with heavy ions Ne, Ar, and Kr of various energies on the structure and properties of ceramic barium cerate doped with neodymium and annealed in air at 650°C for 7 hours is studied. It is noted that blistering was observed on cerate surface during its irradiation by low energy Ne ions, whereas it was not observed under low-energy Ar and Kr ions irradiation. Irradiation of the cerate with high energy ions caused partial amorphization of the irradiated surface of the material, while the structure of the non-irradiated surface did not change. In addition, the irradiated surface of the cerate endured solid-phase structural changes. Thus, upon high-energy ions irradiation in the range of Ne, Ar, Kr the cerate surface resembled the stages of spherulite formation - nucleation, growth (view of cauliflower), formation of spherulitic crust, respectively. The increase in water molecules release and reduction of molecular oxygen release from the barium cerate, irradiated by high-energy ions is found during vacuum constant rate heating. It is concluded that cerates undergo changes to the distances significantly exceeding the ion ranges in these materials. Features of high-energy ions influence on thermal desorption of carbon dioxide from cerates show, apparently, the formation of weakly bound carbonate compounds on the cerate surface in the irradiation process.

Transient analysis of the particle-pellet model with structural changes in the solid phase

Sadhana ◽  
1987 ◽  
Vol 10 (1-2) ◽  
pp. 115-131 ◽  
Author(s):  
C G Dassori ◽  
J W Tierney ◽  
Y T Shah
Keyword(s):  
Transient Analysis ◽  
Structural Changes ◽  
Solid Phase

Direct observation of active material interactions in flowable electrodes using X-ray tomography

2017 ◽  
Vol 199 ◽  
pp. 511-524 ◽  
Author(s):  
Kelsey B. Hatzell ◽  
Jens Eller ◽  
Samantha L. Morelly ◽  
Maureen H. Tang ◽  
Nicolas J. Alvarez ◽  
...  
Keyword(s):  
Structural Properties ◽  
Structural Changes ◽  
Solid Phase ◽  
Active Material ◽  
Carbon Particle ◽  
Three Dimensional ◽  
Static Structure ◽  
Flow Process ◽  
X Ray ◽  
Biphasic Systems

Understanding electrical percolation and charging mechanisms in electrochemically active biphasic flowable electrodes is critical for enabling scalable deionization (desalination) and energy storage. Flowable electrodes are dynamic material systems which store charge (remove ions) and have the ability to flow. This flow process can induce structural changes in the underlying material arrangement and result in transient and non-uniform material properties. Carbon-based suspensions are opaque, multi-phase, and three dimensional, and thus prior characterization of the structural properties has been limited to indirect methods (electrochemical and rheology). Herein, a range of mixed electronic and ionically conducting suspensions are evaluated to determine their static structure, function, and properties, utilizing synchrotron radiation X-ray tomographic microscopy (SRXTM). The high brilliance of the synchrotron light enables deconvolution of the liquid and solid phases. Reconstruction of the solid phase reveals agglomeration cluster volumes between 10 μm3 and 103 μm3 (1 pL) for low loaded samples (5 wt% carbon). The largest agglomeration cluster in the low loaded sample (5 wt%) occupied only 3% of the reconstructed volume whereas samples loaded with 10 wt% activated carbon demonstrated electrically connected clusters that occupied 22% of the imaged region. The highly loaded samples (20 wt%) demonstrated clusters of the order of a microliter, which accounted for 63–85% of the imaged region. These results demonstrate a capability for discerning the structural properties of biphasic systems utilizing SRXTM techniques, and show that discontinuity in the carbon particle networks induces decreased material utilization in low-loaded flowable electrodes.

scholarly journals X-ray tracking of structural changes during a subnanosecond solid-solid phase transition in cobalt nanoparticles

2019 ◽  
Vol 100 (24) ◽  
Author(s):  
Peter Vester ◽  
Morten Christensen ◽  
Elisa Biasin ◽  
Simon O. Mariager ◽  
Gemma Newby ◽  
...  
Keyword(s):  
Phase Transition ◽  
Structural Changes ◽  
Solid Phase ◽  
Cobalt Nanoparticles ◽  
X Ray ◽  
Solid Phase Transition

Molecular studies on structural changes and oligomerisation of violaxanthin de-epoxidase associated with the pH-dependent activation

2016 ◽  
Vol 129 (1) ◽  
pp. 29-41 ◽  
Author(s):  
Erik Ingmar Hallin ◽  
Mahmudul Hasan ◽  
Kuo Guo ◽  
Hans-Erik Åkerlund
Keyword(s):  
Structural Changes ◽  
Molecular Studies ◽  
Ph Dependent

pH Dependent Electrochemical Characterization, Computational Studies and Evaluation of Thermodynamic, Kinetic and Analytical Parameters of Two Phenazines

2014 ◽  
Vol 162 (3) ◽  
pp. H115-H123 ◽  
Author(s):  
Aamir Hassan Shah ◽  
Waqar Zaid ◽  
Afzal Shah ◽  
Usman Ali Rana ◽  
Hidayat Hussain ◽  
...  
Keyword(s):  
Electrochemical Characterization ◽  
Computational Studies ◽  
Ph Dependent

Stability And Precipitation Kinetics In Si1-yCy/Si and Si1-x-yGexC/Si Heterostructures Prepared by Solid Phase Epitaxy

1993 ◽  
Vol 321 ◽  
Author(s):  
J. W. Strane ◽  
S. T. Picraux ◽  
H. J. Stein ◽  
S. R. Lee ◽  
J. Candelaria ◽  
...  
Keyword(s):  
Structural Changes ◽  
Driving Forces ◽  
Solid Phase ◽  
Strain Relaxation ◽  
Solid Phase Epitaxy ◽  
Extended Defects ◽  
Plan View ◽  
Nucleation Barrier ◽  
Transmission Electron ◽  
The Stability

ABSTRACTThis study investigates the stability of Metastable Si1-yCy/Si heterostructures during rapid thermal annealing (RTA) over a temperature range of 1000 – 1150° C Heterostructures of Si1-yCy/Si and Si1-x-yGexCy/Si (x=0.077, y ≤ .0014) were formed by solid phase epitaxy from C implanted, preamorphized substrates using a 30 Minute 700° C anneal in N2. The occupancy of C in substitution lattice sites was monitored by Fourier Transform Infrared Absorption spectroscopy. The layer strain was monitored by rocking curve x-ray diffraction and the structural changes in the layers were determined using plan-view and X-sectional transmission electron Microscopy (TEM). For anneals of 1150° C or above, all the substitutional C was lost from the Si lattice after 30 seconds. TEM verified that the strain relaxation was the result of C precipitating into highly aligned βSiC particles rather than by the formation of extended defects. No nucleation barrier was observed for the loss of substitutional C Preliminary results will also be discussed for Si1-x-yGexCy/Si heterostructures where there is the additional factor of the competition between strain energy and the chemical driving forces.

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