Production of carbon coated Al-foams and evaluation of their mechanical response

2020 ◽  
Vol 27 (5) ◽  
pp. 1399-1407
Author(s):  
F. Stergioudi
2015 ◽  
Vol 91 ◽  
pp. 151-159 ◽  
Author(s):  
F. Stergioudi ◽  
C.A. Vogiatzis ◽  
K. Gkrekos ◽  
N. Michailidis ◽  
S.M. Skolianos

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Alexandra Byakova ◽  
Iegor Kartuzov ◽  
Svyatoslav Gnyloskurenko ◽  
Takashi Nakamura

The results of this study highlight the role of foaming agent and processing route in influencing the contamination of cell wall material by side products, which, in turn, affects the macroscopic mechanical response of closed-cell Al-foams. Several kinds of Al-foams have been produced with pure Al/Al-alloys by the Alporas like melt process, all performed with and without Ca additive and processed either with conventional TiH2foaming agent or CaCO3as an alternative one. Damage behavior of contaminations was believed to affect the micromechanism of foam deformation, favoring either plastic buckling or brittle failure of cell walls. No discrepancy between experimental values of compressive strengths for Al-foams comprising ductile cell wall constituents and those prescribed by theoretical models for closed-cell structure was found while the presence of low ductile and/or brittle eutectic domains and contaminations including particles/layers of Al3Ti, residues of partially reacted TiH2, and Ca bearing compounds, results in reducing the compressive strength to values close to or even below those of open-cell foams of the same relative density.


2010 ◽  
Author(s):  
N. Michailidis ◽  
F. Stergioudi ◽  
H. Omar ◽  
D. N. Tsipas ◽  
Angelos Angelopoulos ◽  
...  

Author(s):  
Sydney S. Breese ◽  
Howard L. Bachrach

Continuing studies on the physical and chemical properties of foot-and-mouth disease virus (FMDV) have included electron microscopy of RNA strands released when highly purified virus (1) was dialyzed against demlneralized distilled water. The RNA strands were dried on formvar-carbon coated electron microscope screens pretreated with 0.1% bovine plasma albumin in distilled water. At this low salt concentration the RNA strands were extended and were stained with 1% phosphotungstic acid. Random dispersions of strands were recorded on electron micrographs, enlarged to 30,000 or 40,000 X and the lengths measured with a map-measuring wheel. Figure 1 is a typical micrograph and Fig. 2 shows the distributions of strand lengths for the three major types of FMDV (A119 of 6/9/72; C3-Rezende of 1/5/73; and O1-Brugge of 8/24/73.


Author(s):  
R. G. Painter ◽  
K. T. Tokuyasu ◽  
S. J. Singer

A technique for localizing intracellular antigens with immunoferritin conjugates directly on ultrathin frozen sections of glutaraldehyde-fixed tissues has been developed. This method overcomes some of the limitations of previously described procedures, since it avoids drastic fixation, dehydration and embedding procedures which could denature many protein antigens.Briefly cells or tissues were fixed with glutaraldehyde (0.5 to 2% for 1 hr), and ultrathin frozen sections were cut and mounted on grids covered with carbon-coated Formvar film by the procedure described previously. Such sections were stained with ferritin-antibody conjugates by methods described elsewhere.


Author(s):  
Dale E. McClendon ◽  
Paul N. Morgan ◽  
Bernard L. Soloff

It has been observed that minute amounts of venom from the brown recluse spider, Loxosceles reclusa, are capable of producing cytotoxic changes in cultures of certain mammalian cells (Morgan and Felton, 1965). Since there is little available information concerning the effect of venoms on susceptible cells, we have attempted to characterize, at the electron microscope level, the cytotoxic changes produced by the venom of this spider.Cultures of human epithelial carcinoma cells, strain HeLa, were initiated on sterile, carbon coated coverslips contained in Leighton tubes. Each culture was seeded with approximately 1x105 cells contained in 1.5 ml of a modified Eagle's minimum essential growth medium prepared in Hank's balanced salt solution. Cultures were incubated at 36° C. for three days prior to the addition of venom. The venom was collected from female brown recluse spiders and diluted in sterile saline. Protein determinations on the venom-were made according to the spectrophotometric method of Waddell (1956). Approximately 10 μg venom protein per ml of fresh medium was added to each culture after discarding the old growth medium. Control cultures were treated similarly, except that no venom was added. All cultures were reincubated at 36° C.


Author(s):  
R. P. Becker ◽  
J. J. Wolosewick ◽  
J. Ross-Stanton

Methodology has been introduced recently which allows transmission and scanning electron microscopy of cell fine structure in semi-thin sections unencumbered by an embedding medium. Images obtained from these “resinless” sections show a three-dimensional lattice of microtrabeculfee contiguous with cytoskeletal structures and membrane-bounded cell organelles. Visualization of these structures, especially of the matiiDra-nous components, can be facilitated by employing tannic acid in the fixation step and dessicator drying, as reported here.Albino rats were fixed by vascular perfusion with 2% glutaraldehyde or 1.5% depolymerized paraformaldehyde plus 2.5% glutaraldehyde in 0.1M sodium cacodylate (pH 7.4). Tissues were removed and minced in the fixative and stored overnight in fixative containing 4% tannic acid. The tissues were rinsed in buffer (0.2M cacodylate), exposed to 1% buffered osmium tetroxide, dehydrated in ethyl alcohol, and embedded in pure polyethylene glycol-6000 (PEG). Sections were cut on glass knives with a Sorvall MT-1 microtome and mounted onto poly-L-lysine, formvar-carbon coated grids while submerged in a solution of 95% ethanol containing 5% PEG.


Author(s):  
S. Edith Taylor ◽  
Patrick Echlin ◽  
May McKoon ◽  
Thomas L. Hayes

Low temperature x-ray microanalysis (LTXM) of solid biological materials has been documented for Lemna minor L. root tips. This discussion will be limited to a demonstration of LTXM for measuring relative elemental distributions of P,S,Cl and K species within whole cells of tobacco leaves.Mature Wisconsin-38 tobacco was grown in the greenhouse at the University of California, Berkeley and picked daily from the mid-stalk position (leaf #9). The tissue was excised from the right of the mid rib and rapidly frozen in liquid nitrogen slush. It was then placed into an Amray biochamber and maintained at 103K. Fracture faces of the tissue were prepared and carbon-coated in the biochamber. The prepared sample was transferred from the biochamber to the Amray 1000A SEM equipped with a cold stage to maintain low temperatures at 103K. Analyses were performed using a tungsten source with accelerating voltages of 17.5 to 20 KV and beam currents from 1-2nA.


Author(s):  
J. P. Robinson ◽  
P. G. Lenhert

Crystallographic studies of rabbit Fc using X-ray diffraction patterns were recently reported. The unit cell constants were reported to be a = 69. 2 A°, b = 73. 1 A°, c = 60. 6 A°, B = 104° 30', space group P21, monoclinic, volume of asymmetric unit V = 148, 000 A°3. The molecular weight of the fragment was determined to be 55, 000 ± 2000 which is in agreement with earlier determinations by other methods.Fc crystals were formed in water or dilute phosphate buffer at neutral pH. The resulting crystal was a flat plate as previously described. Preparations of small crystals were negatively stained by mixing the suspension with equal volumes of 2% silicotungstate at neutral pH. A drop of the mixture was placed on a carbon coated grid and allowed to stand for a few minutes. The excess liquid was removed and the grid was immediately put in the microscope.


Author(s):  
D. L. Rohr ◽  
S. S. Hecker

As part of a comprehensive study of microstructural and mechanical response of metals to uniaxial and biaxial deformations, the development of substructure in 1100 A1 has been studied over a range of plastic strain for two stress states.Specimens of 1100 aluminum annealed at 350 C were tested in uniaxial (UT) and balanced biaxial tension (BBT) at room temperature to different strain levels. The biaxial specimens were produced by the in-plane punch stretching technique. Areas of known strain levels were prepared for TEM by lapping followed by jet electropolishing. All specimens were examined in a JEOL 200B run at 150 and 200 kV within 24 to 36 hours after testing.The development of the substructure with deformation is shown in Fig. 1 for both stress states. Initial deformation produces dislocation tangles, which form cell walls by 10% uniaxial deformation, and start to recover to form subgrains by 25%. The results of several hundred measurements of cell/subgrain sizes by a linear intercept technique are presented in Table I.


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