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What is the primary function of the condenser lens system in a transmission electron microscope?
What is the primary function of the condenser lens system in a transmission electron microscope?
- To provide the formation of either image or diffraction pattern of the specimen
- To focus the electron beam on a spot volume of the specimen
- To magnify the image of the specimen
- To illuminate the specimen with an electron beam of uniform current density (correct)
What is the purpose of the objective lens in a transmission electron microscope?
What is the purpose of the objective lens in a transmission electron microscope?
- To provide the formation of either image or diffraction pattern of the specimen (correct)
- To focus the electron beam on a spot volume of the specimen
- To magnify the electron intensity distribution behind the specimen
- To illuminate the specimen with an electron beam of uniform current density
What is the maximum magnification that can be achieved with a Scanning Electron Microscope?
What is the maximum magnification that can be achieved with a Scanning Electron Microscope?
- 10,000 X
- Less than 3,000 X
- 30,000 X
- More than 300,000 X (correct)
What type of electrons are attracted and collected by a positively biased grid or detector in a Scanning Electron Microscope?
What type of electrons are attracted and collected by a positively biased grid or detector in a Scanning Electron Microscope?
What is the typical acceleration voltage of up-to-date routine transmission electron microscopes?
What is the typical acceleration voltage of up-to-date routine transmission electron microscopes?
What is the primary function of maggots in wound treatment?
What is the primary function of maggots in wound treatment?
What is the significance of the saliva of maggots in wound treatment?
What is the significance of the saliva of maggots in wound treatment?
What is the primary application of scanning electron microscopy (SEM) in medicine?
What is the primary application of scanning electron microscopy (SEM) in medicine?
What is the effect of LGO treatment on E. coli cells as observed under scanning electron microscopy (SEM)?
What is the effect of LGO treatment on E. coli cells as observed under scanning electron microscopy (SEM)?
What is the effect of LGOV treatment on E. coli cells as observed under scanning electron microscopy (SEM)?
What is the effect of LGOV treatment on E. coli cells as observed under scanning electron microscopy (SEM)?
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Study Notes
Microstructure
- Maggots, the larvae of a bluebottle fly, are used medicinally to clean wounds by feeding on dead tissue and leaving healthy tissue untouched.
- The maggots' saliva contains anti-bacterial chemicals that maintain sterility in the wound area.
- Maggots are used to treat ulcers and deep wounds, particularly diabetic ulcers on the feet, away from organs or body cavities.
SEM and TEM Applications
- SEM and TEM are used in:
- Medicine and veterinary medicine for diagnosis and medical research, including developing and testing new drugs.
- Study of materials in other sciences such as archeology, metallurgy, botany, and zoology.
- Development and testing of new materials for industrial use.
Scanning Electron Microscopy (SEM)
- SEM is used to inspect topographies of specimens at very high magnifications, up to 300,000 X.
- Most applications require magnifications of less than 3,000 X.
- SEM uses a focused beam of electrons to dislodge electrons from the specimen, which are then collected and translated into a signal.
- The electron beam is swept across the area being inspected, producing many signals that are amplified, analyzed, and translated into images of the topography.
Transmission Electron Microscopy (TEM)
- TEM is analogous to a slide projector.
- In a conventional TEM, a thin specimen is irradiated with an electron beam of uniform current density.
- Electrons are emitted from the electron gun and illuminate the specimen through a condenser lens system.
- The electron intensity distribution behind the specimen is magnified with a lens system and viewed on a fluorescent screen.
- The image can be recorded by direct exposure of a photographic emulsion or digitally by a CCD camera.
- The acceleration voltage of modern TEM instruments is up to 200 kV.
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