Temperature effects on the nanoindentation characterization of stiffness gradients in confined polymers

Soft Matter ◽  
2019 ◽  
Vol 15 (3) ◽  
pp. 359-370 ◽  
Author(s):  
Jake Song ◽  
Rıdvan Kahraman ◽  
David W. Collinson ◽  
Wenjie Xia ◽  
L. Catherine Brinson ◽  
...  

Stiffness gradients in geometrically confined polymers as measured by nanoindentation are influenced by opposing roles of the polymers viscoelastic state and the degree of confinement.

Author(s):  
L. S. Lin ◽  
K. P. Gumz ◽  
A. V. Karg ◽  
C. C. Law

Carbon and temperature effects on carbide formation in the carburized zone of M50NiL are of great importance because they can be used to control surface properties of bearings. A series of homogeneous alloys (with M50NiL as base composition) containing various levels of carbon in the range of 0.15% to 1.5% (in wt.%) and heat treated at temperatures between 650°C to 1100°C were selected for characterizations. Eleven samples were chosen for carbide characterization and chemical analysis and their identifications are listed in Table 1.Five different carbides consisting of M6C, M2C, M7C3 and M23C6 were found in all eleven samples examined as shown in Table 1. M6C carbides (with least carbon) were found to be the major carbide in low carbon alloys (<0.3% C) and their amounts decreased as the carbon content increased. In sample C (0.3% C), most particles (95%) encountered were M6C carbide with a particle sizes range between 0.05 to 0.25 um. The M6C carbide are enriched in both Mo and Fe and have a fee structure with lattice parameter a=1.105 nm (Figure 1).


Optik ◽  
2017 ◽  
Vol 135 ◽  
pp. 227-237 ◽  
Author(s):  
Antonino Parisi ◽  
Riccardo Pernice ◽  
Andrea Andò ◽  
Alfonso C. Cino ◽  
Vincenzo Franzitta ◽  
...  

2018 ◽  
Author(s):  
Mukul Tewary ◽  
Dominika Dziedzicka ◽  
Joel Ostblom ◽  
Laura Prochazka ◽  
Nika Shakiba ◽  
...  

AbstractIn vitro models of post-implantation human development are valuable to the fields of regenerative medicine and developmental biology. Here, we report characterization of a robust in vitro platform that enabled high-content screening of multiple human pluripotent stem cell (hPSC) lines for their ability to undergo peri-gastrulation-like fate patterning upon BMP4 treatment of geometrically-confined colonies and observed significant heterogeneity in their differentiation propensities along a gastrulation associable and neuralization associable axis. This cell line associated heterogeneity was found to be attributable to endogenous nodal expression, with upregulation of Nodal correlated with expression of a gastrulation-associated gene profile, and Nodal downregulation correlated with a neurulation-associated gene profile expression. We harness this knowledge to establish a platform of pre-neurulation-like fate patterning in geometrically confined hPSC colonies that arises due to a stepwise activation of reaction-diffusion and positional-information. Our work identifies a Nodal signalling dependent switch in peri-gastrulation versus pre-neurulation-associated fate patterning in hPSC cells, provides a technology to robustly assay hPSC differentiation outcomes, and suggests conserved mechanisms of self-organized fate specification in differentiating epiblast and ectodermal tissues.


1986 ◽  
Vol 81 (1) ◽  
pp. 26-29 ◽  
Author(s):  
Stephen M. Southwick ◽  
Thomas L. Davenport

Sensors ◽  
2019 ◽  
Vol 19 (19) ◽  
pp. 4293 ◽  
Author(s):  
Heil ◽  
Schmidhalter

Characterization of spatial soil variability is key for a better understanding of soils. To arrive at such information geophysical techniques have been used in the last two decades. Due to its easy handling, the geophysical sensor EM38 has widely been used to characterize agricultural areas. The theoretical background and usage of the EM38 is described, and based on multifaceted applications, the interpretation of the results as well as optimized steps for using it are outlined. Common principles and models of the apparent electrical conductivity (ECa) and strengths and limitations of this technique (calibration and temperature effects) are described as well as additional applications, such as the magnetic susceptibility, a comparison of measurements in vertical and horizontal modes, the use of weighted depth information and the influence of measurement conditions are addressed. Further a comparison of EM38 with other proximal soil sensors and fusion with other devices is described. The study reveals that EM38 is useful because the readings can reflect many different soil parameters.


1997 ◽  
Vol 119 (3) ◽  
pp. 284-291 ◽  
Author(s):  
J. Zhang ◽  
Z. Lin ◽  
A. Wong ◽  
N. Kikuchi ◽  
V. C. Li ◽  
...  

In this study, mechanical properties of three types of polymeric foams (polypropylene (PP), polystyrene (PS), and polyurethane (PU) foams) are investigated. Focus has been placed on the strain rate and temperature effects on these foams under large deformations. Selected experimental results from uniaxial compression, hydrostatic compression, and simple shear tests are presented. A phenomenological hydrodynamic elastoplastic constitutive law is developed to model these polymeric foams. Numerical implementation and validation of the constitutive model are also described.


2021 ◽  
Vol 10 (10) ◽  
pp. e396101019020
Author(s):  
Igor Magno Nicurgo Borges Rosa Martins ◽  
Luanna Stefanny Vieira Oliveira Gomes ◽  
Daniel Pasquini ◽  
Milla Alves Baffi

The enzyme biosynthesis using agricultural wastes by solid state fermentation (SSF) and the study of their physicochemical properties are meaningful approaches to improve the biomass hydrolysis. Among them, β-glucosidases and β-xylosidases are key enzymes at the lignocellulose depolymerization, which act in the cleavage of oligosaccharides in monosaccharides. In this study, the production of hemicellulases and cellulases by Pleurotus ostreatus and Aspergillus niger monocultures or in consortium was investigated, using raw sugarcane bagasse (SB) and wheat bran (WB) as substrates. The highest enzymatic activities were observed in the crude extract produced by P. ostreatus PLO6 and A. niger SCBM4 consortium with 98.5, 62.9, 3.8, 12.4, 13.3 and 20.2 U/g for β-glucosidase (β-glu), β-xylosidase (Bxyl), filter paper cellulase (FPase), xylanase (Xyl), exoglucanase (Exgl) and endoglucanase (Engl), respectively. The pH and temperature effects on β-glu and β-xyl were characterized. Optimal activities were obtained at pH 4.0 and 45 °C for β-glu and 3.5 and 55 °C for β-xyl. Both enzymes were stable at acid pH and presented thermostability. The results indicated that the enzymatic cocktail demonstrated potential characteristics for future applications in saccharifications. The use of sugarcane bagasse and wheat bran for microbial growth contributed to aggregate value to these byproducts.


1968 ◽  
Vol 14 (4) ◽  
pp. 397-402 ◽  
Author(s):  
Marvin D. Brailsford ◽  
Paul A. Hartman

Streptococcus durans bacteriophages were isolated from bovine rumen fluid, feed lot soil, bovine fecal samples, and lysogenic strains of S. durans. The presence of different phage strains was suggested by antiserum neutralization tests and one-step growth characteristics, whereby the bacteriophages were placed into three distinct, but serologically related, groups. These phages were further characterized by plaque morphology, phage morphology, adsorption kinetics, and pH and temperature effects.


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