Pyramid morphology

The polyethylene crystals shown in Fig. 4.11 exist as hollow pyramids made up of planar sections. Since the solvent must be evaporated away prior to electron microscopic observation, the pyramids become buckled, torn, and/ or pleated during the course of sample preparation. While the pyramidal morphology is clearly evident in Fig. 4.1 la, there is also evidence of collapse and pleating. Likewise, the ridges on the apparently planar crystals in Fig. 4.1 lb are pleats of excess material that bunches up when the pyramids collapse. 

Figure 5.8 shows some typical neuron morphologies. The motor neuron is found in the spinal cord. It is an efferent type bringing information from the central nervous system (CNS) to a muscle or gland, for example. The receptor type is an afferent neuron with a special direct axon coupling between the receptor and the CNS. The pyramid morphology is found in the cortex of the brain. 

The present review shows how the microhardness technique can be used to elucidate the dependence of a variety of local deformational processes upon polymer texture and morphology. Microhardness is a rather elusive quantity, that is really a combination of other mechanical properties. It is most suitably defined in terms of the pyramid indentation test. Hardness is primarily taken as a measure of the irreversible deformation mechanisms which characterize a polymeric material, though it also involves elastic and time dependent effects which depend on microstructural details. In isotropic lamellar polymers a hardness depression from ideal values, due to the finite crystal thickness, occurs. The interlamellar non-crystalline layer introduces an additional weak component which contributes further to a lowering of the hardness value. Annealing effects and chemical etching are shown to produce, on the contrary, a significant hardening of the material. The prevalent mechanisms for plastic deformation are proposed. Anisotropy behaviour for several oriented materials is critically discussed. 

The morphology of alkaline-etched (100) and (110) silicon surfaces varies from rough surfaces that exhibit micron-sized pyramids or ridges [Sc5] to smooth orange peel-like surfaces, depending on the etchant composition and substrate doping density. Mirror-like surfaces can be obtained on (111) crystal planes. 

Note A lamellar crystal is usually of a thickness in the 5-50 nm range, and it may be found individually or in aggregates. The parallel-chain stems intersect the lamellar plane at an angle between 45° and 90°. The lamellae often have pyramidal shape owing to differences in the fold domains, as a result, one can deduce different fold planes and fold surfaces from the lamellar morphology. 

To achieve a strict time control of principal cells, GABAergic interneurons display several remarkable features. (1) Their action potential is traditionally faster than that of pyramidal cells and the kinetics of synaptic events that excite inhibitory cells are faster than those that excite pyramidal cells (Martina et al. 1998 Geiger et al. 1997). (2) The GABAergic interneurons are morphologically highly diverse, which reflects their multiple functions in neuronal networks... 

Table 3). They have been detected both functionally (Table 3) and, morphologically, by comparison of the distribution of H3 receptor mRNA and H3 receptor protein. By the latter approach it has been shown, for example, that thalamo-cortical and hippocampal pyramidal glutamate neurons and striato-nigral as well as striato-pallidal GABA neurons possess presynaptic H3 receptors (see Pillot et al. 2002 Jin and Panula 2005 see also immunohistochemical detection in Section 3.9). 

The Fe content in the deposit can be varied from 100 to 50 atom% by decreasing the deposition potential or the Fe(II) concentration in the solution. SEM images of the deposits revealed that they were dense and compact, and the morphology varied from nodules to pyramidal and hexagonal as the iron content in the deposits decreased. 

Figure 6 TEM characterization of the structure and morphology of Pd nanoparticles supported on MgO(l 0 0). (a) Electron diffraction pattern (b) top-view micrograph (c) profile view micrograph of an individual particle (d) drawing of the truncated octahedron shape of a Pd particle (e) shape of a large coalesced particle (0 truncated pyramid shape of a small (<7 nm) Pd particle.

Law AJ, Harrison PJ. 2003. The distribution and morphology of prefrontal cortex pyramidal neurons identified using anti-neurofilament antibodies SMI32, N200 and FNP7. Normative data and a comparison in subjects with schizophrenia, bipolar disorder or major depression. J Psychiatr Res 37(6) 487-499. 

Lewis DA, Glantz LA, Pierri JN, Sweet RA. 2003. Altered cortical glutamate neurotransmission in schizophrenia Evidence from morphological studies of pyramidal neurons. Ann NY Acad Sci 1003 102-112. 

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