scholarly journals Solid-State Biology and Seed Longevity: A Mechanical Analysis of Glasses in Pea and Soybean Embryonic Axes

2019 ◽  
Vol 10 ◽  
Author(s):  
Daniel Ballesteros ◽  
Christina Walters
IUCrJ ◽  
2015 ◽  
Vol 2 (6) ◽  
pp. 611-619 ◽  
Author(s):  
Gamidi Rama Krishna ◽  
Ramesh Devarapalli ◽  
Rajesh Prusty ◽  
Tiandong Liu ◽  
Cassandra L. Fraser ◽  
...  

The structure and mechanical properties of crystalline materials of three boron difluoride dibenzoylmethane (BF2dbm) derivatives were investigated to examine the correlation, if any, among mechanochromic luminescence (ML) behaviour, solid-state structure, and the mechanical behaviour of single crystals. Qualitative mechanical deformation tests show that the crystals of BF2dbm(tBu)2can be bent permanently, whereas those of BF2dbm(OMe)2exhibit an inhomogeneous shearing mode of deformation, and finally BF2dbmOMe crystals are brittle. Quantitative mechanical analysis by nanoindentation on the major facets of the crystals shows that BF2dbm(tBu)2is soft and compliant with low values of elastic modulus,E, and hardness,H, confirming its superior suceptibility for plastic deformation, which is attributed to the presence of a multitude of slip systems in the crystal structure. In contrast, both BF2dbm(OMe)2and BF2dbmOMe are considerably stiffer and harder with comparableEandH, which are rationalized through analysis of the structural attributes such as the intermolecular interactions, slip systems and their relative orientation with respect to the indentation direction. As expected from the qualitative mechanical behaviour, prominent ML was observed in BF2dbm(tBu)2, whereas BF2dbm(OMe)2exhibits only a moderate ML and BF2dbmOMe shows no detectable ML, all examined under identical conditions. These results confirm that the extent of ML in crystalline organic solid-state fluorophore materials can be correlated positively with the extent of plasticity (low recovery). In turn, they offer opportunities to design new and improved efficient ML materials using crystal engineering principles.


1985 ◽  
Vol 9 (3) ◽  
pp. 137-141 ◽  
Author(s):  
H. Tobushi ◽  
J.R. Gahoon

The mechanical principle of a solar-powered solid state engine utilizing the shape-memory effect is analyzed. The performance of a differential pulley Nitinol engine is discussed and it is calculated that a small, solar-powered differential pulley Nitinol engine could produce up to 15W with a single Nitinol wire, A higher power solar Nitinol engine producing up to 15 kW is possible by using larger Nitinol wire, and over 1 MW may be expected by applying the higher power engine system. The size of the solar energy collector needed to generate mechanical energy via a Nitinol engine is estimated to be about 0.02 m2/W and the total efficiency of the engine predicted to be about 4%, The overall efficiency and economics of a solar-powered Nitinol engine should be in the same order as that of solar energy system utilizing the photovoltaic effect.


2008 ◽  
Vol 141-143 ◽  
pp. 439-443 ◽  
Author(s):  
Shou Jing Luo ◽  
Qiang Chen ◽  
Xiao Rong Gao

Rheological behavior of semi-solid metals during isothermal compression is the most basic forming way for semi-solid die forging. In this paper, based on the metal plastic deformation and high pressure solidification theory, the shear deformation mechanisms of semi-solid metals were analyzed during isothermal compression. Experimental observations and theoretical analyses for AZ91D and composite Al/Al2O3 in the semi-solid state were performed with thermal simulation tests. The results for theoretical analyses and experimental observations show that the shear deformation of semi-solid metals has been realized by metal inhomogeneous flowing from macroscopic view and by grain boundary inhomogeneous migrating from microscopic view respectively during compression.


2019 ◽  
Vol 285 ◽  
pp. 385-390
Author(s):  
Marialaura Tocci ◽  
Annalisa Pola ◽  
Michael Modigell

Dynamic Mechanical Analysis (DMA) of semisolid aluminum alloys was performed in a rheometer of Searle type. DMA was applied on a binary AlSi7 alloy to demonstrate the advantages of the method for the investigation of the behavior of alloys in semi-solid state and it was compared to classical shear experiments. Frequency sweeps, amplitude sweeps as well as constant condition experiments (CCE) were performed. It became obvious that elastic properties are getting more dominant with increasing resting time without shearing. The shift from a more viscous to more elastic nature of the material can be quantified. Interestingly, it was found that the semi-empirically based Cox-Merz rule, usually applied for polymers, holds for the semisolid material as well. This allows investigating the shear viscosity under different relevant conditions - important to improve material models for die-filling simulation of semisolid alloys.


2010 ◽  
Vol 660-661 ◽  
pp. 1130-1136 ◽  
Author(s):  
Carolina A. Pinto ◽  
Jo Dweck ◽  
John J. Sansalone ◽  
Frank K. Cartledge ◽  
L.T. Hamassaki ◽  
...  

This paper presents a study of a stabilization/solidification (S/S) process of a tannery waste containing chromium. In this process a mixture of cement, water and the waste is solidified during hydration of the former. Stabilization occurs by the reaction of the chromium components of the waste with the calcium hydroxide formed during the process. A rigid block is obtained with low hazardous of contamination of soil and groundwater after its disposal into industrial landfill. Mixtures were prepared adding dried tannery waste in 10, 15 and 20% of the Portland cement mass. Sodium bentonite and organoclays in 5 % of cement mass were used as additives. Solidified specimens were analyzed after 28 days of hydration time by solid-state 29Si nuclear magnetic resonance (NMR) spectroscopy and unconfined compressive strength analysis. The increase of tannery waste content and the presence of the additives reduce silica polymerization as well as the mechanical strength of the solidified bodies.


2011 ◽  
Vol 12 (4) ◽  
pp. 1380-1386 ◽  
Author(s):  
Carmiña Gartner ◽  
Betty Lucy López ◽  
Ligia Sierra ◽  
Robert Graf ◽  
Hans W. Spiess ◽  
...  

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