scholarly journals Comparative Study of Leaf Surface Texture and Ability to Expand of Cured Tobacco

2001 ◽  
Vol 19 (7) ◽  
pp. 333-338
Author(s):  
R Rohr ◽  
A Eberhard ◽  
R Delon ◽  
JP Descombes ◽  
JM Demor
Keyword(s):  
Electron Microscopy ◽  
Leaf Surface ◽  
Point Of View ◽  
Relative Importance ◽  
Palisade Parenchyma ◽  
Adaxial Side ◽  
Objective Criterion ◽  
Transmission Electron ◽  
The Difference ◽  
Expansion Capacity

AbstractTobacco leaf texture, appreciated by the difference of surface roughness of cured leaves, is studies with light microscopy and scanning electron microscopy (SEM). The leaf texture is obviously determined by the presence or absence of conical cellular protuberances on the adaxial side of the leaf. Considering the anatomic point of view, the leaf thickness, always more important when the leaf texture is open, is the only objective criterion which could be associated to the texture. The ultra-structural study with SEM and transmission electron microscopy (TEM) demonstrates that the expansion capacity of tobacco doesn't rely on cytological factors such as cellular reserves or debris. The expansion capacity could be inversely proportional with the relative importance of the mesophyll comparing to palisade parenchyma. On the studied material, no direct relation between the leaf texture and the expansion capacity has been noticed.

scholarly journals Effect of Aging Time on Crushing Performance of Al-0.5Mg-0.4Si Alloy for Safety Components of Automobile

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 608
Author(s):  
Jinkun Lu ◽  
Haichun Jiang ◽  
Lingying Ye ◽  
Daxiang Sun ◽  
Yong Zhang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Tensile Test ◽  
Aging Time ◽  
Uniform Elongation ◽  
Total Elongation ◽  
Localized Deformation ◽  
Ductility Index ◽  
Transmission Electron ◽  
The Difference

The effect of aging time on the crushing performance of Al-0.5Mg-0.4Si alloy used for safety components of automobile was investigated by tensile test and crush test. Moreover, the microstructure of the alloy was investigated by transmission electron microscopy (TEM). The results show that the localized deformation ductility index, ΔAabs, which is defined as the difference between total elongation and uniform elongation, of Al-0.5Mg-0.4Si alloy is 6.5%, 7.0% and 8.5%, respectively, after being aged at 210 °C for 1, 3 and 6 h, and this tendency is the same as that of the crushing performance. The spacing of grain boundary precipitates (GBPs) from TEM results are found to be 94.9, 193.6 and 408.2 nm after being aged at 210 °C for 1, 3 and 6 h, respectively, and this tendency is same to that of ΔAabs. A mechanism about the relation between the spacing of GBPs and the ductility index ΔAabs has been proposed based on localized deformation around GBPs. With the increase of GBPs spacing, the ΔAabs increases, and the crushing performance is improved.

Influence of doping on crystal growth, structure and optical properties of nanocrystalline CaTiO3: a case study using small-angle neutron scattering

2015 ◽  
Vol 48 (3) ◽  
pp. 836-843 ◽  
Author(s):  
Oindrila Mondal ◽  
Manisha Pal ◽  
Ripandeep Singh ◽  
Debasis Sen ◽  
Subhasish Mazumder ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Optical Properties ◽  
Crystal Growth ◽  
Small Angle Neutron Scattering ◽  
Ionic Radius ◽  
Ionic Radii ◽  
Growth Structure ◽  
Transmission Electron ◽  
The Difference

The effect of dopant size (ionic radius) on the crystal growth, structure and optical properties of nanocrystalline calcium titanate, CaTiO3(CTO), have been studied using small-angle neutron scattering. X-ray diffraction, along with high-resolution transmission electron microscopy, confirms the growth of pure nanocrystalline CTO. Rietveld analysis reveals that the difference of ionic radii between dopant and host ions induces strain within the lattice, which significantly affects the lattice parameters. The induced strain, due to the difference of ionic radii, causes the shrinkage of the optical band gap, which is manifested by the redshift of the absorbance band. Mesoscopic structural analysis using scattering techniques demonstrates that the ionic radius of the dopant influences the agglomeration behaviour and particle size. A high-resolution transmission electron microscopy study reconfirms the formation of pure highly crystalline CTO nanoparticles.

Development of New Marker Compounds for the Detection of Chemical Element Labels by Electron Spectroscopic Imaging (ESI)

2001 ◽  
Vol 7 (S2) ◽  
pp. 1038-1039
Author(s):  
S. Raddatz ◽  
E. P. Mark ◽  
A. Haking ◽  
W. Probst ◽  
M. Wiessler ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Chemical Element ◽  
Three Dimensional ◽  
Point Of View ◽  
High Concentration ◽  
Specific Chemical ◽  
Energy Filtering ◽  
Transmission Electron ◽  
Gold Particle Size ◽  
Marker Compounds

A promising aspect of ESI is its application in the detection of elemental labels introduced into biomolecules for cell and molecular biological techniques. Even though colloidal gold labeling for electron microscopy (EM) is highly developed, availability of alternative labels, especially for double or triple labeling applications would be helpful because of difficulties with gold concerning i) detection (gold diameters ≤1nm), ii) discrimination due to gold particle size variations in one size class, and iii) different labeling efficiencies depending on gold granule size. An alternative labeling molecule should contain a high concentration of a specific chemical element which is not or in minor concentrations present in the system under surveillance, and has to have the potential to be discriminated from “biological” elements by ESI.With respect to ESI, one candidate for elemental labeling is boron. It meets the criteria described above and substantial experience in the synthesis of labeling compounds exists. From the chemical point of view, the preferred labeling structure is a so called dendrimer, a highly branched regular three-dimensional monodisperse macromolecule. Dendritic structures offer a large variety of functionalities to incorporate an element detectable by energy filtering transmission electron microscopy (EFTEM).

scholarly journals Deposits of iron oxides in the human globus pallidus

Open Physics ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 291-298
Author(s):  
Helena Svobodová ◽  
Jana Hlinková ◽  
Pavol Janega ◽  
Daniel Kosnáč ◽  
Barbora Filová ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Human Brain ◽  
Iron Oxides ◽  
Globus Pallidus ◽  
Room Temperature ◽  
Hysteresis Loops ◽  
Point Of View ◽  
Zero Field ◽  
Fixed Temperature ◽  
Transmission Electron

Abstract Samples taken from the human brain (Globus Pallidus) have been investigated by physical techniques such as light microscopy, scanning electron microscopy, transmission electron microscopy, Mössbauer spectroscopy and SQUID magnetometry. SEM-EDX/TEM investigation reveals multielemental composition of hematite and magnetite nanocrystals with sizes ranging from 40 nm to 100 nm and hematite microcrystals from 3 μm to 7 μm. Room temperature Mössbauer spectra show quadrupole doublets assigning to hematite and ferrihydrite. SQUID measurements of temperature dependence of the mass magnetic susceptibility between T = 2 – 300 K at DC field B0 = 0.1 T, the field dependence of the mass magnetization taken at the fixed temperature T0 = 2.0 and 4.6 K and the zero-field cooled and field cooled magnetization experiments (ZFCM/FCM) confirm a presence of ferrimagnetic phases such as maghemite and/or magnetite with hysteresis loops surviving until the room temperature. Differences between these measurements from the point of view of iron oxides detected can indicate important processes in human brain and interactions between ferritin as a physiological source of iron and surrounding environment.

Three-Dimensional Chemistry of Multiphase Nanomaterials by Energy-Filtered Transmission Electron Microscopy Tomography

2012 ◽  
Vol 18 (5) ◽  
pp. 1118-1128 ◽  
Author(s):  
Lucian Roiban ◽  
Loïc Sorbier ◽  
Christophe Pichon ◽  
Pascale Bayle-Guillemaud ◽  
Jacques Werckmann ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Tomography ◽  
Three Dimensional ◽  
Point Of View ◽  
Analysis Tool ◽  
Shell Nanoparticles ◽  
3D Nanostructures ◽  
Transmission Electron ◽  
Silica Alumina

AbstractA three-dimensional (3D) study of multiphase nanostructures by chemically selective electron tomography combining tomographic approach and energy-filtered imaging is reported. The implementation of this technique at the nanometer scale requires careful procedures for data acquisition, computing, and analysis. Based on the performances of modern transmission electron microscopy equipment and on developments in data processing, electron tomography in the energy-filtered imaging mode is shown to be a very appropriate analysis tool to provide 3D chemical maps at the nanoscale. Two examples highlight the usefulness of analytical electron tomography to investigate inhomogeneous 3D nanostructures, such as multiphase specimens or core-shell nanoparticles. The capability of discerning in a silica-alumina porous particle the two different components is illustrated. A quantitative analysis in the whole specimen and toward the pore surface is reported. This tool is shown to open new perspectives in catalysis by providing a way to characterize precisely 3D nanostructures from a chemical point of view.

Nanoporous Ni and Ni-Cu Fabricated by Dealloying

2009 ◽  
Vol 1228 ◽  
Author(s):  
Masataka Hakamada ◽  
Yasumasa Chino ◽  
Mamoru Mabuchi
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Noble Metals ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
The Difference ◽  
20 Nm ◽  
Good Workability ◽  
Scanning Electron

AbstractMetallic nanoporous architecture can be spontaneously attained by dealloying of a binary alloy. The nanoporous architecture can be often fabricated in noble metals such as Au and Pt. In this study, nanoporous Ni, Ni-Cu are fabricated by dealloying rolled Ni-Mn and Cu-Ni-Mn alloys, respectively. Unlike conventional Raney nickel composed of brittle Ni-Al or Cu-Al intermetallic compounds, the initial alloys had good workability probably because of their fcc crystal structures. After the electrolysis of the alloys in (NH4)2SO4 aqueous solution, nanoporous architectures of Ni and Ni-Cu with pore and ligament sizes of 10–20 nm were confirmed by scanning electron microscopy and transmission electron microscopy. X-ray diffraction analyses suggested that Ni and Cu atoms form a homogeneous solid solution in the Ni-Cu nanoporous architecture. The ligament sizes of nanoporous Ni and Ni-Cu were smaller than that of nanoporous Cu, reflecting the difference between diffusivities of Ni and Cu at solid/electrolyte interface. Ni can reduce the pore and ligament sizes of resulting nanoporous architecture when added to initial Cu-Mn alloys.

Microsporogenesis and microgametogenesis of Cardiospermum grandiflorum and Urvillea chacoensis (Sapindaceae, Paullinieae)

2010 ◽  
Vol 58 (7) ◽  
pp. 597 ◽  
Author(s):  
Stella M. Solís ◽  
Beatriz Galati ◽  
María S. Ferrucci
Keyword(s):  
Electron Microscopy ◽  
Pollen Grains ◽  
Basic Type ◽  
Anther Wall ◽  
Anther Dehiscence ◽  
Transmission Electron ◽  
Pollen Ontogeny ◽  
Tapetal Cells ◽  
The Difference ◽  
Mature Anther

Microsporogenesis and microgametogenesis of two species, Cardiospermum grandiflorum Sw. and Urvillea chacoensis Hunz. (Sapindaceae, Paullinieae), were studied using light and transmission electron microscopy. Both species are monoecious, with staminate and hermaphrodite, although functionally pistillate, flowers. A comparative pollen-development study of these two floral morphs is reported. For the present study, five stages of pollen ontogeny were identified. The development of the anther wall is of basic type. Its wall consists of epidermis, endothecium, two middle layers and a uninucleate secretory tapetum. The microspore tetrads are tetrahedral. The mature anther in staminate flowers presents the endothecium with well developed fibrillar thickenings, remains of tapetal cells, a single locule formed in the theca by dissolution of the septum before anther dehiscence and two-celled pollen grains when shed. In functionally pistillate flowers, the mature anthers present remnants of the middle layers, tapetal cells without signs of degradation, the theca with two locules and pollen grains uni- or bicellular, some of them with the cytoplasm collapsed. These anthers are not dehiscent. It can be concluded that male sterility is characterised by failure to produce functional pollen grains, an event that would be associated with the persistence of tapetal cells. Ultrastructural analysis clearly shows the difference in tapetal cells between the two flower morphs.

Collenchyma in Panicum maximum (Poaceae): localisation and possible role

2003 ◽  
Vol 51 (1) ◽  
pp. 69 ◽  
Author(s):  
Elder A. S. Paiva ◽  
Sílvia R. Machado
Keyword(s):  
Electron Microscopy ◽  
Leaf Blade ◽  
Sudden Change ◽  
Panicum Maximum ◽  
Vascular Bundles ◽  
Serial Sections ◽  
Adaxial Side ◽  
Transition Area ◽  
Transmission Electron ◽  
Phases Of Development

This work relates the occurrence and distribution of collenchyma in Panicum maximum Jacq. P.�maximum leaves were collected at different phases of development and sampled from both the base of the sheath and from the sheath–leaf blade transition area. For the stems, the study was made by using hand-cut sections of the internodal base. In the leaves, analyses of serial sections showed, at the base and sheath–leaf blade transition area, a sudden change of tissue at vascular bundle. The vascular bundles are surrounded by sclerenchyma, both in the sheath and the leaf blade, as well as by fibrous threads that occur on the adaxial side of the central bundles. However, at the base of the sheath and at the sheath–leaf blade transition area, sclerenchyma was substituted for collenchyma. In the stem, the substitution of sclerenchyma associated with vascular bundles for collenchyma occurs at the base of the internode, in the pulvinus region. The analyses from transmission electron microscopy showed the presence of lamellated cell wall and active protoplast in collenchyma cells.

scholarly journals Surface and Ultrastructural Feeding Injury to Strawberry Leaves by the Twospotted Spider Mite

HortScience ◽  
1990 ◽  
Vol 25 (8) ◽  
pp. 948-951 ◽  
Author(s):  
Richard J. Campbell ◽  
Randolph L. Grayson ◽  
Richard P. Marini
Keyword(s):  
Spider Mite ◽  
Leaf Surface ◽  
Twospotted Spider Mite ◽  
Fragaria Ananassa ◽  
Lower Leaf Surface ◽  
Palisade Parenchyma ◽  
Mesophyll Cells ◽  
Transmission Electron ◽  
Vascular Elements ◽  
Twospotted Spider

Scanning and transmission electron microscopy were used to investigate damage to strawberry (Fragaria ×ananassa Duch.) leaves caused by twospotted spider mite (Tetranychus urticae Koch.). Mites damaged epidermal cells on the lower leaf surface, but did not damage major vascular elements of the leaf. Mite-damaged spongy and palisade parenchyma cells had coagulated protoplasts, with some cells devoid of cellular contents. Mesophyll cells adjacent to damaged regions showed no ultrastructural distortion or disruption of chloroplasts.

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