Scanning electron imaging of mellitophilous and allergenic pollen grain of arid and northern irrigated agroecological zones of Pakistan

2021 ◽  
Author(s):  
Mehwish Jamil Noor ◽  
Mushtaq Ahmad
Keyword(s):  
Pollen Grain ◽  
Allergenic Pollen ◽  
Agroecological Zones ◽  
Electron Imaging ◽  
Scanning Electron

Remarks on the application of backscattered electron imaging (BEI) to the scanning electron microscopy (SEM) of biological structures

1983 ◽  
Vol 41 ◽  
pp. 484-487
Author(s):  
Etienne de Harven
Keyword(s):  
High Resolution ◽  
Incident Beam ◽  
Spot Size ◽  
Primary Electron ◽  
Critical Point Drying ◽  
Cell Shapes ◽  
High Resolution Images ◽  
Backscattered Electron ◽  
Electron Imaging ◽  
Scanning Electron

Biological ultrastructures have been extensively studied with the scanning electron microscope (SEM) for the past 12 years mainly because this instrument offers accurate and reproducible high resolution images of cell shapes, provided the cells are dried in ways which will spare them the damage which would be caused by air drying. This can be achieved by several techniques among which the critical point drying technique of T. Anderson has been, by far, the most reproducibly successful. Many biologists, however, have been interpreting SEM micrographs in terms of an exclusive secondary electron imaging (SEI) process in which the resolution is primarily limited by the spot size of the primary incident beam. in fact, this is not the case since it appears that high resolution, even on uncoated samples, is probably compromised by the emission of secondary electrons of much more complex origin.When an incident primary electron beam interacts with the surface of most biological samples, a large percentage of the electrons penetrate below the surface of the exposed cells.

Observation of GaAs/AlAs Superlattice Structures in both Secondary and Backscattcred Electron Imaging Modes with an Ultrahigh Resolution Scanning Electron Microscope

1990 ◽  
Vol 48 (1) ◽  
pp. 404-405
Author(s):  
K. Ogura ◽  
A. Ono ◽  
S. Franchi ◽  
P.G. Merli ◽  
A. Migliori
Keyword(s):  
Gaas Layer ◽  
Objective Lens ◽  
Superlattice Structure ◽  
Backscattered Electron ◽  
Instrumental Resolution ◽  
Electron Microscopes ◽  
Superlattice Structures ◽  
Electron Imaging ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

In the last few years the development of Scanning Electron Microscopes (SEM), equipped with a Field Emission Gun (FEG) and using in-lens specimen position, has allowed a significant improvement of the instrumental resolution . This is a result of the fine and bright probe provided by the FEG and by the reduced aberration coefficients of the strongly excited objective lens. The smaller specimen size required by in-lens instruments (about 1 cm, in comparison to 15 or 20 cm of a conventional SEM) doesn’t represent a serious limitation in the evaluation of semiconductor process techniques, where the demand of high resolution is continuosly increasing. In this field one of the more interesting applications, already described (1), is the observation of superlattice structures.In this note we report a comparison between secondary electron (SE) and backscattered electron (BSE) images of a GaAs / AlAs superlattice structure, whose cross section is reported in fig. 1. The structure consist of a 3 nm GaAs layer and 10 pairs of 7 nm GaAs / 15 nm AlAs layers grown on GaAs substrate. Fig. 2, 3 and 4 are SE images of this structure made with a JEOL JSM 890 SEM operating at an accelerating voltage of 3, 15 and 25 kV respectively. Fig. 5 is a 25 kV BSE image of the same specimen. It can be noticed that the 3nm layer is always visible and that the 3 kV SE image, in spite of the poorer resolution, shows the same contrast of the BSE image. In the SE mode, an increase of the accelerating voltage produces a contrast inversion. On the contrary, when observed with BSE, the layers of GaAs are always brighter than the AlAs ones , independently of the beam energy.

Scanning Electron Microscopy and Secondary-Electron Imaging Microscopy

2012 ◽  
pp. 2280-2280
Author(s):  
Yimei Zhu ◽  
Hiromi Inada ◽  
Achim Hartschuh ◽  
Li Shi ◽  
Ada Della Pia ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Secondary Electron ◽  
Electron Imaging ◽  
Scanning Electron

scholarly journals Variations and abnormalities of stamen morphologies in cornelian cherry (Cornus mas L.) cultivars

2009 ◽  
Vol 36 (No. 3) ◽  
pp. 109-116 ◽  
Author(s):  
C. Mert ◽  
A. Soylu
Keyword(s):  
Surface Morphology ◽  
Pollen Grain ◽  
Epidermal Cells ◽  
Filament Length ◽  
Cornelian Cherry ◽  
Floral Organs ◽  
Cornus Mas ◽  
Scanning Electron

: Stamen morphologies of six cornelian cherry cultivars (Degirmendere, Erkenci Degirmendere, İri Bardak, Yuvarlak Bardak, Uzun Memeli, and Bugur) (<I>Cornus mas</I> L.) were evaluated using scanning electron, light and stereo microscopes. Flowers of cornelian cherry cultivars generally had four stamens, but a few of them had three or five stamens. Abnormal and normal stamens were found together in the cultivars examined. Percentages of abnormal stamens among the cultivars ranged from 12% to 22%. Various types of stamen abnormalities were identified in the cultivars such as variations in filament length, abnormalities in anther structure, fusion of stamen to other floral organs. Pollen grain numbers per anther varied between 1,380 and 4,240 among the cultivars. Abnormal anther surface morphology in the cultivars consisted of uneven and swollen epidermal cells. Anther dimensions varied between 624.00 and 1,001.25 &mu;m in length and 460.50 and 745.50 &mu;m in width. Anthers of all the cultivars had subprolate and prolate type of shapes.

scholarly journals Forescattered electron imaging of nanoparticles in scanning electron microscopy

2019 ◽  
Vol 155 ◽  
pp. 109814 ◽  
Author(s):  
Junliang Liu ◽  
Sergio Lozano-Perez ◽  
Phani Karamched ◽  
Jennifer Holter ◽  
Angus J. Wilkinson ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Electron Imaging ◽  
Scanning Electron
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