Microstructure PDF

Microstructure  A coloured scanning electron micrograph (SEM) of the head of a maggot or the larva of a bluebottle fly (Protophormia sp.) with tiny teeth-like fangs extending from its mouth. The maggots of this fly are used medicinally to clean wounds. The maggots are sterilised and...

Microstructure  A coloured scanning electron micrograph (SEM) of the head of a maggot or the larva of a bluebottle fly (Protophormia sp.) with tiny teeth-like fangs extending from its mouth. The maggots of this fly are used medicinally to clean wounds. The maggots are sterilised and placed in the wound, where they feed on dead tissue and leave healthy tissue untouched. Their saliva contains anti- bacterial chemicals which maintain sterility in the area. Maggots are used on ulcers and deep wounds away from organs or body cavities, most often being used to treat diabetic ulcers on the feet  SEM & TEM for diagnosis (based on analysis of diseased tissues) in medicine and veterinary medicine medical research including the development and testing of new drugs study of materials - living or otherwise - in other sciences such as archeology, metallurgy, botany, zoology development and testing of new materials for use in industry. (A) (B) (C) Scanning electron micrographs of untreated and treated E. coli cells. (a) Untreated cells with normal smooth surfaces (×30.00 K). (b) Shrunken, aggregated, and partially deformed LGO- treated cells (×30.00 K). (c) Completely destroyed and ruptured LGOV-treated cells (×30.00 K).  (B) (C) (A) Transmission electron micrographs of untreated and treated E. coli cells. (a) Untreated E. coli cells having a regular outlined cell wall, plasma lemma lying closely to the cell wall, and regularly distributed cytoplasm. (b) LGO-treated E. coli cells having variable cell wall thickness appearing disrupted and variable periplasmic spaces (shown by arrows). (c) LGOV-treated cells having extensive internal damage, unsymmetrically distributed cytoplasm, and larger and irregular periplasmic spaces (shown by arrows).  Scanning Electron Microscopy (SEM) (SEM) and TEM  Scanning Electron Microscopy (SEM) used for inspecting topographies of specimens at very high magnifications. SEM magnifications can go to more than 300,000 X applications require magnifications of less than 3,000 X. a beam of electrons is focused on a spot volume of the specimen, resulting in the transfer of energy to the spot. These bombarding electrons, also referred to as primary electrons, dislodge electrons from the specimen itself. The dislodged electrons, also known as secondary electrons, are attracted and collected by a positively biased grid or detector, and then translated into a signal. To produce the SEM image, the electron beam is swept across the area being inspected, producing many such signals. These signals are then amplified, analyzed, and translated into images of the topography being inspected. Transmission Electron Microscopy (TEM) A transmission Electron Microscope is anologous to a slide projector as indicated by Philips below In a conventional transmission electron microscope, 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 two or three stage condenser lens system. Objective lens provides the formation of either image or diffraction pattern of the specimen. The electron intensity distribution behind the specimen is magnified with a three or four stage lens system and viewed on a fluorescent screen. The image can be recorded by direct exposure of a photographic emulsion or an image plate or digitally by a CCD camera. The acceleration voltage of up to date routine instruments is 120 to 200 kV. Medium- voltage instruments work at 200-500 kV to provide a better transmission and resolution, and in high voltage electron microscopy (HVEM) the acceleration voltage is in the range 500 kV to 3 MV. Acceleration voltage determines the velocity, wavelength and hence the resolution (ability to distinguish the neighbouring microstructural features) of the microscope. Depending on the aim of the investigation and configuration of the microscope, transmission electron microscopy can be categorized as : Conventional Transmission Electron Microscopy High Resolution Electron Microscopy Analytical Electron Microscopy Energy-Filtering Electron Microscopy High Voltage Electron Microscopy Dedicated Scanning Transmission Electron Microscopy (SEM) and TEM mitochondria