Nanoindentation near the edge

2009 ◽  
Vol 24 (3) ◽  
pp. 1016-1031 ◽  
Author(s):  
J.E. Jakes ◽  
C.R. Frihart ◽  
J.F. Beecher ◽  
R.J. Moon ◽  
P.J. Resto ◽  
...  
Keyword(s):  
Loblolly Pine ◽  
Cell Walls ◽  
Aluminum Matrix ◽  
Free Edge ◽  
Silicon On Insulator ◽  
Depth Data ◽  
Thin Film On Substrate ◽  
Polypropylene Matrix ◽  
Structural Compliance ◽  
Spurious Results

Whenever a nanoindent is placed near an edge, such as the free edge of the specimen or heterophase interface intersecting the surface, the elastic discontinuity associated with the edge produces artifacts in the load–depth data. Unless properly handled in the data analysis, the artifacts can produce spurious results that obscure any real trends in properties as functions of position. Previously, we showed that the artifacts can be understood in terms of a structural compliance, Cs, which is independent of the size of the indent. In the present work, the utility of the SYS (Stone, Yoder, Sproul) correlation is demonstrated in its ability to remove the artifacts caused by Cs. We investigate properties: (i) near the surface of an extruded polymethyl methacrylate rod tested in cross section, (ii) of compound corner middle lamellae of loblolly pine (Pinus taeda) surrounded by relatively stiff wood cell walls, (iii) of wood cell walls embedded in a polypropylene matrix with some poorly bonded wood–matrix interfaces, (iv) of AlB2 particles embedded in an aluminum matrix, and (v) of silicon-on-insulator thin film on substrate near the free edge of the specimen.

Experimental method to account for structural compliance in nanoindentation measurements

2008 ◽  
Vol 23 (4) ◽  
pp. 1113-1127 ◽  
Author(s):  
J.E. Jakes ◽  
C.R. Frihart ◽  
J.F. Beecher ◽  
R.J. Moon ◽  
D.S. Stone
Keyword(s):  
Pinus Taeda ◽  
Loblolly Pine ◽  
Experimental Approach ◽  
Free Edge ◽  
Fused Silica ◽  
Wood Composite ◽  
Calibration Standard ◽  
Standard Analysis ◽  
Polypropylene Matrix ◽  
Structural Compliance

The standard Oliver–Pharr nanoindentation analysis tacitly assumes that the specimen is structurally rigid and that it is both semi-infinite and homogeneous. Many specimens violate these assumptions. We show that when the specimen flexes or possesses heterogeneities, such as free edges or interfaces between regions of different properties, artifacts arise in the standard analysis that affect the measurement of hardness and modulus. The origin of these artifacts is a structural compliance (Cs), which adds to the machine compliance (Cm), but unlike the latter, Cs can vary as a function of position within the specimen. We have developed an experimental approach to isolate and remove Cs. The utility of the method is demonstrated using specimens including (i) a silicon beam, which flexes because it is supported only at the ends, (ii) sites near the free edge of a fused silica calibration standard, (iii) the tracheid walls in unembedded loblolly pine (Pinus taeda), and (iv) the polypropylene matrix in a polypropylene–wood composite.

Loblolly pine seedling root anatomy and iron accumulation as affected by soil waterlogging

1987 ◽  
Vol 17 (10) ◽  
pp. 1257-1264 ◽  
Author(s):  
M. R. McKevlin ◽  
D. D. Hook ◽  
W. H. Mckee Jr. ◽  
S. U. Wallace ◽  
J. R. Woodruff
Keyword(s):  
Loblolly Pine ◽  
Cell Walls ◽  
Cortical Cell ◽  
Root Anatomy ◽  
Intercellular Spaces ◽  
Seedling Root ◽  
Aeration System ◽  
Pine Seedlings ◽  
Epidermal Surface ◽  
Bordered Pits

Loblolly pine seedlings were grown under flooded and drained conditions in a greenhouse pot study. Flooded roots developed aerenchyma tissue within the stele between the xylem poles, extending from the phloem outward to the pericycle. Large intercellular spaces were present in the pericyclic parenchyma within the phellogen of flooded woody roots. Flooded stems exhibited lenticel hypertrophy. Large intercellular spaces in the cortex were continuous with intercellular spaces in the pericyclic parenchyma of the root. Flooding of roots generally resulted in accumulation of Fe on the epidermal surface and in as well as between cortical cell walls inward to the endodermis. Fe accumulated in and between the precursor phloem cells and became more evident in the region of maturation. In roots with secondary thickening, little Fe was visible in the phloem but was present in helical secondary walls of tracheids. Fe also accumulated on and in bordered pits of root tracheids. Results suggest that flooded loblolly pine seedlings possess a limited internal aeration system and that diffusion of oxygen into the root system may be responsible for the presence of oxidized Fe within the stele.

Effect of thermo-mechanical refining pressure on the properties of wood fibers as measured by nanoindentation and atomic force microscopy

Holzforschung ◽  
2008 ◽  
Vol 62 (2) ◽  
pp. 230-236 ◽  
Author(s):  
Cheng Xing ◽  
Siqun Wang ◽  
George M. Pharr ◽  
Leslie H. Groom
Keyword(s):  
Mechanical Properties ◽  
Atomic Force Microscopy ◽  
Loblolly Pine ◽  
Cell Walls ◽  
Physical And Mechanical Properties ◽  
Wood Fibers ◽  
Cross Sectional ◽  
Force Microscopy ◽  
Mechanical Refining ◽  
Atomic Force

Abstract Refined wood fibers of a 54-year-old loblolly pine (Pinus taeda L.) mature wood were investigated by nanoindentation and atomic force microscopy (AFM). The effect of steam pressure, in the range of 2–18 bar, during thermo-mechanical refining was investigated and the nano-mechanical properties and nano- or micro-level damages of the cell wall were evaluated. The results indicate that refining pressure has important effects on the physical and mechanical properties of refined fibers. No obvious damage was observed in the cell walls at pressures between 2 and 4 bar. Nano-cracks (most less than 500 nm in width) were found in fibers at pressures in the range of 6–12 bar, and micro-cracks (more than 5 μm in width) were found in fibers subjected to pressures of 14 and 18 bar. The damages caused at higher pressures were more severe in layers close to the lumen than on the fiber surfaces. Under special circumstances, the S3 layer was heavily damaged. The natural shape of the cross sectional dimensions of the cell walls was not changed at lower pressures (2 and 4 bar), but, as pressure was increased, the fibers tended to collapse. At pressures around 18 bar, the lumina were augmented again. The nano-mechanical properties in terms of elastic modulus and hardness were obviously decreased, while nanoindentation creep increased with refining pressure.

Ectodesmata as Revealed By Freeze-Etch Preparations of Plant Epidermal Cell Walls

1973 ◽  
Vol 31 ◽  
pp. 468-469
Author(s):  
N.C. Lyon ◽  
W. C. Mueller
Keyword(s):  
Electron Microscopy ◽  
Acetic Acid ◽  
Nitric Acid ◽  
Oxalic Acid ◽  
Light Microscopy ◽  
Epidermal Cell ◽  
Cell Walls ◽  
Plant Viruses ◽  
Plant Leaves ◽  
Thin Sections

Schumacher and Halbsguth first demonstrated ectodesmata as pores or channels in the epidermal cell walls in haustoria of Cuscuta odorata L. by light microscopy in tissues fixed in a sublimate fixative (30% ethyl alcohol, 30 ml:glacial acetic acid, 10 ml: 65% nitric acid, 1 ml: 40% formaldehyde, 5 ml: oxalic acid, 2 g: mecuric chloride to saturation 2-3 g). Other workers have published electron micrographs of structures transversing the outer epidermal cell in thin sections of plant leaves that have been interpreted as ectodesmata. Such structures are evident following treatment with Hg++ or Ag+ salts and are only rarely observed by electron microscopy. If ectodesmata exist without such treatment, and are not artefacts, they would afford natural pathways of entry for applied foliar solutions and plant viruses.

An ultrastructural study of vegetative incompatibility in plants

1978 ◽  
Vol 36 (2) ◽  
pp. 436-437
Author(s):  
Randy Moore
Keyword(s):  
Ultrastructural Study ◽  
Cell Walls ◽  
Growth And Development ◽  
Solanum Pennellii ◽  
Initial Product ◽  
Basic Aspect ◽  
Tissue Interactions ◽  
Graft Interface ◽  
Antigen Antibody ◽  
Standard Fixation

Cell and tissue interactions are a basic aspect of eukaryotic growth and development. While cell-to-cell interactions involving recognition and incompatibility have been studied extensively in animals, there is no known antigen-antibody reaction in plants and the recognition mechanisms operating in plant grafts have been virtually neglected.An ultrastructural study of the Sedum telephoides/Solanum pennellii graft was undertaken to define possible mechanisms of plant graft incompatibility. Grafts were surgically dissected from greenhouse grown plants at various times over 1-4 weeks and prepared for EM employing variations in the standard fixation and embedding procedure. Stock and scion adhere within 6 days after grafting. Following progressive cell senescence in both Sedum and Solanum, the graft interface appears as a band of 8-11 crushed cells after 2 weeks (Fig. 1, I). Trapped between the buckled cell walls are densely staining cytoplasmic remnants and residual starch grains, an initial product of wound reactions in plants.

Comparison of Substructures Between Uniaxial and Biaxial Deformation in 1100-0 Aluminum

1981 ◽  
Vol 39 ◽  
pp. 52-53
Author(s):  
D. L. Rohr ◽  
S. S. Hecker
Keyword(s):  
Plastic Strain ◽  
Cell Walls ◽  
Room Temperature ◽  
Mechanical Response ◽  
Biaxial Tension ◽  
Initial Deformation ◽  
Uniaxial Deformation ◽  
Biaxial Deformation ◽  
Stress States ◽  
Comprehensive Study

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.

Structural changes in silicon-on-insulator material during post-implantation annealing

1986 ◽  
Vol 44 ◽  
pp. 736-737
Author(s):  
C. O. Jung ◽  
S. J. Krause ◽  
S.R. Wilson
Keyword(s):  
Integrated Circuits ◽  
Oxide Layer ◽  
High Speed ◽  
Structural Changes ◽  
Device Fabrication ◽  
Silicon On Insulator ◽  
High Quality ◽  
Radiation Hardened ◽  
Post Implantation ◽  
Very High

Silicon-on-insulator (SOI) structures have excellent potential for future use in radiation hardened and high speed integrated circuits. For device fabrication in SOI material a high quality superficial Si layer above a buried oxide layer is required. Recently, Celler et al. reported that post-implantation annealing of oxygen implanted SOI at very high temperatures would eliminate virtually all defects and precipiates in the superficial Si layer. In this work we are reporting on the effect of three different post implantation annealing cycles on the structure of oxygen implanted SOI samples which were implanted under the same conditions.

In Situ microscopy of the anodic etching of silicon

1995 ◽  
Vol 53 ◽  
pp. 232-233
Author(s):  
Frances M. Ross ◽  
Peter C. Searson
Keyword(s):  
Composite Structures ◽  
High Surface ◽  
High Surface Area ◽  
Chemical Properties ◽  
Selective Etching ◽  
Silicon On Insulator ◽  
Second Phase ◽  
Porous Layers ◽  
New Class ◽  
Porous Semiconductors

Porous semiconductors represent a relatively new class of materials formed by the selective etching of a single or polycrystalline substrate. Although porous silicon has received considerable attention due to its novel optical properties1, porous layers can be formed in other semiconductors such as GaAs and GaP. These materials are characterised by very high surface area and by electrical, optical and chemical properties that may differ considerably from bulk. The properties depend on the pore morphology, which can be controlled by adjusting the processing conditions and the dopant concentration. A number of novel structures can be fabricated using selective etching. For example, self-supporting membranes can be made by growing pores through a wafer, films with modulated pore structure can be fabricated by varying the applied potential during growth, composite structures can be prepared by depositing a second phase into the pores and silicon-on-insulator structures can be formed by oxidising a buried porous layer. In all these applications the ability to grow nanostructures controllably is critical.

Cryosectioning plant roots prepared by high-pressure freezing

1987 ◽  
Vol 45 ◽  
pp. 662-663
Author(s):  
R.E. Crang ◽  
M. Mueller ◽  
K. Zierold
Keyword(s):  
High Pressure ◽  
Cell Walls ◽  
Plant Tissues ◽  
Ice Crystal ◽  
High Pressure Freezing ◽  
Vitreous State ◽  
Radial Depth ◽  
Irregular Topography ◽  
Considerable Depth ◽  
Conventional Freezing

Obtaining frozen-hydrated sections of plant tissues for electron microscopy and microanalysis has been considered difficult, if not impossible, due primarily to the considerable depth of effective freezing in the tissues which would be required. The greatest depth of vitreous freezing is generally considered to be only 15-20 μm in animal specimens. Plant cells are often much larger in diameter and, if several cells are required to be intact, ice crystal damage can be expected to be so severe as to prevent successful cryoultramicrotomy. The very nature of cell walls, intercellular air spaces, irregular topography, and large vacuoles often make it impractical to use immersion, metal-mirror, or jet freezing techniques for botanical material.However, it has been proposed that high-pressure freezing (HPF) may offer an alternative to the more conventional freezing techniques, inasmuch as non-cryoprotected specimens may be frozen in a vitreous, or near-vitreous state, to a radial depth of at least 0.5 mm.

Analysis of Silicon-On-Insulator Structures Formed By Oxygen Ion Implantation

1985 ◽  
Vol 43 ◽  
pp. 300-301
Author(s):  
N. Lewis ◽  
E. L. Hall ◽  
A. Mogro-Campero ◽  
R. P. Love
Keyword(s):  
Ion Implantation ◽  
Single Crystal ◽  
Single Crystal Silicon ◽  
Silicon Layer ◽  
Device Fabrication ◽  
Silicon On Insulator ◽  
High Dose ◽  
Crystal Silicon ◽  
Oxygen Ion ◽  
Oxygen Ion Implantation

The formation of buried oxide structures in single crystal silicon by high-dose oxygen ion implantation has received considerable attention recently for applications in advanced electronic device fabrication. This process is performed in a vacuum, and under the proper implantation conditions results in a silicon-on-insulator (SOI) structure with a top single crystal silicon layer on an amorphous silicon dioxide layer. The top Si layer has the same orientation as the silicon substrate. The quality of the outermost portion of the Si top layer is important in device fabrication since it either can be used directly to build devices, or epitaxial Si may be grown on this layer. Therefore, careful characterization of the results of the ion implantation process is essential.

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