Frictionless nanoscale plastic flows of soft solid He-4

2013 ◽  
Vol 91 (3) ◽  
pp. 268-272 ◽  
Author(s):  
Chu W. Kwang-Hua
Keyword(s):  
Activation Energy ◽  
High Pressure ◽  
Activation Volume ◽  
Strain Rates ◽  
High Shear ◽  
Vycor Glass ◽  
Fixed Concentration ◽  
Very High ◽  
Solid He

Possible onset of the quantum plasticity in soft–solid He-4 was discovered recently in 7 nm diameter (Vycor glass) nanopores. Here, by using the transition-state model together with the specific activation energy and activation volume, we investigated the possible frictionless plastic flows of soft–solid He-4 under high pressure in confined nanodomains and we observed a series of sudden changes in the shearing stresses at corresponding very high shear strain rates of (locally amorphous) soft–solid He-4 for different activation volumes considering the role of He-3 impurities. Our calculated critical velocity for a fixed concentration of He-3 quantitatively agrees with recent reported values.

Platelet-Mediated Mechanical Tensile Force Influences ADAMTS13 Localization and Regulation Of Thrombus Development At The Site Of Platelet Accumulation

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 454-454
Author(s):  
Yasuaki Shida ◽  
Laura L. Swystun ◽  
Christine Brown ◽  
Jeff Mewburn ◽  
Kate Sponagle ◽  
...  
Keyword(s):  
Thrombus Formation ◽  
Tensile Force ◽  
Flow Chamber ◽  
High Shear ◽  
Wild Type ◽  
Hydrodynamic Shear ◽  
Chamber Model ◽  
Mechanical Tensile ◽  
Very High

Background The multimeric glycoprotein von Willebrand factor (VWF) mediates platelet adhesion and aggregation at the site of vessel injury. The adhesive property of VWF is regulated by its multimer length, such that ultra large VWF (ULVWF) multimers, newly released from the endothelium, have greater hemostatic activity. multimer size is regulated by the metalloprotease ADAMTS13, which cleaves the A2 domain to reduce VWF multimer size and functional activity. static conditions, VWF maintains a globular conformation and the ADAMTS13 cleavage site is inaccessible. However, the exposure of endothelial-anchored VWF to tensile forces mediated by platelets and hydrodynamic shear enhance the cleavage of VWF by ADAMTS13. releases VWF of optimal hemostatic length from the endothelium into the plasma. We have previously reported using a flow chamber model which demonstrates that in addition to regulating VWF length and activity at the site of release, ADAMTS13 also associates with VWF at the site of thrombus formation. observed that under conditions of high and very high shear, ADAMTS13 reduced the size of thrombus volume., multi-coloured immunostaining revealed that ADAMTS13 co-localized with VWF and platelets at the top and middle layers of the thrombus, in the presence of very high shear. Aim To better understand the mechanism by which ADAMTS13 regulates thrombus size in our flow chamber model, we assessed the contribution of platelet tensile force to the localization of ADAMTS13 at the site of the thrombus. this model, the contributions of platelet GPIb, GPIIbIIIa, and P-selectin to ADAMTS13 localization were observed. Method Full length mouse VWF and ADAMTS13 cDNA were cloned into pCIneo and pcDNA3.1 plasmid, respectively. The gain of platelet GPIb binding mutation V1316M, and loss of GPIIbIIIa binding mutation (RGD to RGG) were introduced by site-directed-mutagenesis. mCherry was cloned at the C terminus of ADAMTS13 with a 12AA linker. Recombinant mVWF and mADAMTS13-mCherry proteins were produced via HEK293T cells by calcium phosphate transient transfection. mADAMTS13-mCherry (2 U/mL) and wild type or mutant mVWF (4 U/mL) was added to whole blood obtained from VWF-/-/ADAMTS13-/- double knockout mice. Whole blood containing DiOC6-labeled platelets was perfused over a collagen coated flow chamber at very high shear (7500s-1). The role of P-selectin was also analyzed by adding a P-selectin blocking antibody to blood obtained from ADAMTS13-/-knockout mice prior to the flow chamber experiment. After the perfusion, thrombi were fixed and immunostaining was performed to further analyze the distribution of platelets, VWF and ADAMTS13. Result As previously reported, ADAMTS13 localization was observed in the top and middle layers of the thrombus in the presence of wild type mVWF. The GPIb gain-of-function mutation V1316M increased both platelet (126%, p<0.0001) and VWF (190% and p<0.0001) accumulation at the thrombus site. ADAMTS13 localization was also increased (135%, p<0.001) relative to the binding to wild type VWF. Interestingly, with this gain-of-function VWF mutant, ADAMTS13 localization was found throughout the entire thrombus. In contrast, the GPIIbIIIa RGD binding mutant demonstrated decreased VWF (56%, p<0.01), and ADAMTS13 (82%, p<0.05) intensity, although platelet intensity was unaffected. to wild type, ADAMTS13 localized to the middle and top layers of the thrombus. Finally, inhibition of P-selectin significantly decreased VWF (46%, p<0.01) and ADAMTS13 (34%, p<0.01) localization to the thrombus, but again did not significantly alter platelet binding. Conclusion These studies demonstrate the central role of platelet-mediated mechanical tensile force on the regulation of thrombus growth at the site of platelet accumulation. Enhanced tensile force induced by increased GPIb binding resulted in increased ADAMTS13 localization, while reduced tensile force through loss of GPIIbIIIa or P-selectin binding decreased ADAMTS13 localization. This suggests that ADAMTS13 activity at the site of thrombus formation is maintained by the combination of hydrodynamic shear force and platelet tethering. aggregate, these studies suggest that under conditions of shear, ADAMTS13 regulates thrombus size by preserving the hemostatic function of the thrombus, and preventing dysregulated thrombus growth. Disclosures: No relevant conflicts of interest to declare.

Die Kinetik des Zerfalls von tert. Butylperoxypivalat bei hohen Drücken und Temperaturen / The Kinetics of the Decomposition of tert.Butylperoxypivalate up to High Pressures and Temperatures

1981 ◽  
Vol 36 (12) ◽  
pp. 1371-1377 ◽  
Author(s):  
M. Buback ◽  
H. Lendle
Keyword(s):  
Activation Energy ◽  
High Pressure ◽  
High Pressures ◽  
Activation Volume ◽  
Rate Law ◽  
First Order ◽  
Order Rate ◽  
High Pressures And Temperatures ◽  
Kinetics Of

AbstractThe decomposition of tert. butylperoxypivalate dissolved in n-heptane has been measured ir-spectroscopically in optical high-pressure cells up to 2000 bar at temperatures between 65 °C and 105 °C. The reaction follows a first order rate law with an activation energy Ea = 122.3 ±3.0 kJ · mol-1 and an activation volume ⊿V≠ = 1.6 ± 1.0 cm3 mol-1 .

A New Apparatus to Shear Bulk Materials at Various Rates Under Very High Pressure

1970 ◽  
Vol 92 (1) ◽  
pp. 137-138 ◽  
Author(s):  
A. E. Abey ◽  
H. D. Stromberg
Keyword(s):  
High Pressure ◽  
Plastic Region ◽  
Strain Rates ◽  
Bulk Materials ◽  
Stress Strain ◽  
New Apparatus ◽  
Very High

The apparatus described will shear bulk materials at strain rates from 2 × 10−5/sec to 5 × 10−1/sec while the materials are under nearly hydrostatic pressures. This apparatus gives complete stress-strain curves in the plastic region at pressures from about 10 kbar to approximately 80 kbar. Data on beryllium are given as an example of the type of data available from this apparatus.

scholarly journals Role of Vanadium Addition on Hot Deformation Behavior of Aluminum Alloy 5083

Metals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 766
Author(s):  
Wang ◽  
Wang ◽  
Zhu ◽  
Xu ◽  
Cui ◽  
...  
Keyword(s):  
Activation Energy ◽  
Grain Size ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Strain Rates ◽  
Processing Maps ◽  
Compression Tests ◽  
Hot Deformation Behavior ◽  
Aluminum Alloy 5083

The effect of V addition on the hot deformation behavior of AA5083 was investigated. Single axial compression tests were conducted on the cast and homogenized samples with strain rates ranging from 0.01 to 10 s−1 and deformation temperatures ranging from 300 to 450 °C. The results showed that the contents of V (0–0.10, in wt.%) do not change the grain size of alloy 5083 significantly in the as cast and homogenized conditions, but the formation of fine Al3V particles in the alloy with an addition of 0.05 wt.% V can increase the flow stress, and its activation energy is 10.0% higher than that of V-free alloy 5083. The processing maps show that the appropriate process domain for alloy 5083 with 0.05 wt.% V changes at different true strains. The mechanism for deformation softening is discussed as well.

scholarly journals Influence of High Conductive Magnetite Impurity on the Electrical Conductivity of Dry Olivine Aggregates at High Temperature and High Pressure

Minerals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 44 ◽  
Author(s):  
Lidong Dai ◽  
Haiying Hu ◽  
Wenqing Sun ◽  
Heping Li ◽  
Changcai Liu ◽  
...  
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
High Pressure ◽  
Percolation Threshold ◽  
Atmospheric Pressure ◽  
Activation Volume ◽  
Activation Enthalpy ◽  
Frequency Range ◽  
Arrhenius Relation ◽  
Conductivity Anomalies

The electrical conductivity of dry sintered olivine aggregates with various contents of magnetite (0, 3, 5, 7, 10, 20, and 100 vol. %) was measured at temperatures of 873–1273 K and a pressure of 2.0 GPa within a frequency range of 0.1–106 Hz. The changes of the electrical conductivity of the samples with temperature followed an Arrhenius relation. The electrical conductivity of the sintered olivine aggregates increased as the magnetite-bearing content increased, and the activation enthalpy decreased, accordingly. When the content of interconnected magnetite was higher than the percolation threshold (~5 vol. %), the electrical conductivity of the samples was markedly enhanced. As the pressure increased from 1.0 to 3.0 GPa, the electrical conductivity of the magnetite-free olivine aggregates decreased, whereas the electrical conductivity of the 5 vol. % magnetite-bearing sample increased. Furthermore, the activation energy and activation volume of the 5 vol. % magnetite-bearing sintered olivine aggregates at atmospheric pressure were calculated to be 0.16 ± 0.04 eV and −1.50 ± 0.04 cm3/mole respectively. Due to the high value of percolation threshold (~5 vol. %) in the magnetite impurity sample, our present results suggest that regional high conductivity anomalies in the deep Earth’s interior cannot be explained by the presence of the interconnected magnetite-bearing olivine aggregates.

scholarly journals How is charge transport different in ionic liquids? The effect of high pressure

2017 ◽  
Vol 19 (21) ◽  
pp. 14141-14147 ◽  
Author(s):  
Z. Wojnarowska ◽  
E. Thoms ◽  
B. Blanchard ◽  
S. N. Tripathy ◽  
P. Goodrich ◽  
...  
Keyword(s):  
High Pressure ◽  
Ionic Liquids ◽  
Charge Transport ◽  
Transport Properties ◽  
Activation Volume

In this paper the key role of the apparent activation volume parameter in the charge transport properties of protic and aprotic ionic liquids is demonstrated.

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