Welcome to Microscopes Blog
Microscopes Blog is dedicated entirely to microscopes, industry-related news and product reviews. We try to do our best in providing our readers with the most adequate and truthful reviews on all microscopes products and their accessories. And we tend to share our thoughts on anything related to the fascinating field of microscopy. So if you share our passion of exploring the tiny objects that are too small for the naked eye to see, this blog is for you!
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Researchers at Oak Ridge National Laboratory have developed a way to write on the nano scale using a scanning transmission electron microscope, STEM. The scientists at the Center for Nanophase Materials Sciences, CNMS - a DOE Office at ORNL, carried out the research. The team at CNMS weaved the aberration corrected sub-nanometer electron probe of the STEM through a Palladium solution (H2PdCl4) in a liquid cell to deposit the metal onto a Silicon microchip. The focused and controlled electron beam strikes the microchip and pure Palladium is deposted. Currently lithography is used to create patterns at the nano scale where the areas which are not to be imprinted with material are masked.
The liquid cell is made of a microchip with a Silicon Nitride membrane window through which the electron beam can pass. A sealed cell is required as it must be placed in the vacuum inside the electron microscope. Accurate control of the electron beam is critical to success of this nano lithography. The interface with the scan coils in the aberration corrected STEM is used to direct the electron beam position, speed, and dose. The current resolution of the “writing” is 40 nm. The researches at CNMS are working toward 10nm, current nanolithography can achieve this resolution.
“Direct-write liquid phase transformations with a scanning transmission electron microscope” Nanoscale, 2016,8, 15581-15588
The Leica EZ4 W microscope is being used by the US Department of State in the fight against drug trafficking. Stereo zoom microscopes like the EZ4 W are uniquely appropriate for forensics studies because they image in 3D. Three dimensional objects can be placed on the stage of the microscope unlike compound microscopes which use microscopes slides. Compound microscopes have a flat field and the image appears upside down and backwards whereas with a stereo microscope the image is magnified exactly as the object is placed on the stage. The image from the object is slightly offset for each eye (hence the name “stereo”) and the object appears just as the eye sees it only magnified. Stereo microscopes are used in fingerprinting, ballistics, fiber analysis, counterfeiting, and a host of other forensic applications. The EZ4 W can also store the images received on the included SD card. Application software has analysis capabilities such as measuring and comparison. An optional remote control is available for projecting the images on the SD card onto an HD screen. In addition to the above capabilities the image quality of the EZ4 W is what you would expect from Leica, remarkably clear at even the highest magnifications.
Finally, there is a cell imaging system able to eliminate the challenges and complexities of microscopy – without compromising performance. Enter the EVOS Cell Imaging System. Whether you’re capturing images for publications, teaching, or research, the EVOS system was designed to allow users to focus on their data rather than the operation of the microscope.
Built to perform a variety of routine and specialty applications, EVOS Imaging Systems can handle everything from cell cultures to complex protein analysis. For sensitive applications that require precise control of the environment one can add the onstage incubator. The proprietary LED light cube technology minimizes photobleaching and offers over 50,000 hours of LED illumination, along with adjustable intensity. The EVOS Imaging System gives your laboratory high level imaging capability without the high cost typically associated with fluorescence imaging systems.
There are five Cell Imaging Systems to choose from:
EVOS XL Core
- EVOS XL
- EVOS FLoid
- EVOS FL
- EVOS FL Auto
Interested? Learn more about the entire EVOS Cell Imaging System Lineup by clicking the link below: EVOS Cell Imaging Microscopes
Unless you’ve been living on Neptune for the past three months, then you know that Ebola is all everyone is talking about. One things for certain, there is a ton of misinformation going out to the general public. We want to set the record straight on what exactly the disease is.
First things first, how is the disease transmitted? According to the World Health Organization “Ebola is introduced into the human population through close contact with the blood, secretions, organs or other bodily fluids of infected animals such as chimpanzees, gorillas, fruit bats, monkeys, forest antelope and porcupines found ill or dead or in the rainforest.” Once it makes its way to a human being from one of the above animals, “Ebola then spreads through human-to-human transmission via direct contact (through broken skin or mucous membranes) with the blood, secretions, organs or other bodily fluids of infected people, and with surfaces and materials (e.g. bedding, clothing) contaminated with these fluids.” To sum it up, you can get it through bodily fluids.
How to know if you might have it:
According to the W.H.O “The incubation period, that is, the time interval from infection with the virus to onset of symptoms is 2 to 21 days. Humans are not infectious until they develop symptoms. First symptoms are the sudden onset of fever fatigue, muscle pain, headache and sore throat. This is followed by vomiting, diarrhea, rash, symptoms of impaired kidney and liver function, and in some cases, both internal and external bleeding (e.g. oozing from the gums, blood in the stools). Laboratory findings include low white blood cell and platelet counts and elevated liver enzymes.”
How to make sure you don’t get it:
- Reduce the chance of animal-to-human transmission from contact with infected fruit bats or monkeys. This includes the consumption of their raw meat. Handle animals with gloves and other appropriate protective clothing. Should you deal with animal blood or meat, make sure to thoroughly cook it before eating.
- Reducing the chance of person to person transmission from direct or close proximity contact with people that display symptoms of Ebola. Gloves and appropriate personal protective equipment should be worn if you are taking care of sick or ill patients at home. Regularly wash hands after coming in contact with people during your normal day to day activities.
The motility of bacteria is provided by the flagella, a rigid helical structure that extends up to 10 microns out from the cell. Flagella allow cells to move towards nutrients or away from harmful substances such as acids in a process known as chemotaxis. Flagella are less than .2 microns thick and therefore are below the resolution of the light microscope. In order for the flagella to be viewed they must be stained using a special procedure. A single flagellum is composed of a rigid filament that occurs in the form a single helix. This makes up the main body of the flagellum structure. The filament is connected to a hook that is attached to a shaft that is inserted into a series of rings. The shaft is inserted into a series of rings. The number of rings differs depending on whether the cell is gram-positive or gram-negative. The shaft rings along with other accessory proteins make up the basal body of the flagellum. Proteins associated with the basal body transport protons across the cell membrane which creates a charge differential. This charge differential forces the rings to rotate which results in the rotation of the shaft, hook, and filament.
Acid fast staining is used to stain bacteria with mycolic acid in their cell walls. The Ziehl-Neelsen staining method is used which involves mixing carbolfuchsin with phenol and heating the cells for 5 minutes. Phenol allows the penetration of carbolfuchsin into the cell wall and the heat further fixes the stain. The cells are then treated with acid-alcohol which acts as a decolorizer however it does not remove the stain from the mycolic acid-carbolfuchsin complex. These cells are referred to as acid-fast. Cells that do not contain mycolic acid in their cell walls are decolorized by the acid-alcohol and referred to as non-acid-fast. Non-acid-fast bacteria are counterstained with methylene blue and appear blue under the microscope. Acid-fast cells appear red to pink in stained preparations. Heating the cells with phenol can create fumes that may damage mucus membranes and eyes. The staining method may be modified to prevent these fumes. The concentrations of phenol and carbolfuchsin may be increased however no heat is used.
Bacteria such as mycobacterium have cell walls that contain a high lipid content. One of the cell wall lipids is a waxy material called mycolic acid. Mycolic acid is a complex lipid that is made of fatty acids and fatty alcohols and have carbon chains up to 80 carbons in length. Mycolic acid significantly affects the staining properties of these bacteria and prevents them from being stained by many of the stains routinely used in microbiology. The acid fast stain is an important tool in the identification of Mycobacterium tuberculosis, the organism that causes tuberculosis and Mycobacterium leprae, the bacterium that causes leprosy in humans. Mycolic acid makes the cell wall impermeable to many stains. In order to stain bacteria with high lipid content one must use a technique that makes them more permeable to stains. The Ziehl-Neelsen method and the Kinyoun acid-fast method will be discussed in next week’s post.
In the previous post we discussed the unique properties of endospores. These unique properties mean that they are not easily penetrated by stains. If endospore containing cells are stained by crystal violet, the spores appear as unstained areas in the vegetative cell. If heat is applied while staining with malachite green, the stain penetrates the endospore and green is not removed by subsequent washing with decolorizing agents or water. In this situation heat is acting as a mordant much like iodine in a gram stain procedure. There are two methods for spore staining. The Schaeffer-Fulton method uses malachite green to stain the endospore and safranin to stain the vegetative portion of the cell. A properly stained spore forming cell will have a green endospore contained in a pink sporangium. The Dorner method produces a red spore with a colorless sporangium. Nigrosin is used to provide a dark background. Both the sporangium and endospore are stained however the safranin diffuses out of the sporangium and into the nigrosin leaving a colorless sporangium.
When bacteria belonging to the genus Bacillus or Clostridium run out of essential nutrients, they produce endospores. Endospores allow the bacteria to survive extreme conditions that are not optimal for growth. If conditions become favorable, the endospore can go through a process called germination and form a new vegetative cell. Endospores are dehydrated structures and are not actively metabolizing. Endospores are also resistant to heat, radiation, acids, and many chemicals such as disinfectants that normally harm and kill vegetative cells. Endospores are resistant due to their protein coat or exosporium that forms a protective barrier around the spore. Heat resistance is directly correlated with water content. The higher the water content of the cell the less resistant to heat it will be. The water content of the spore is 10-30%. The water content is low because calcium ions form a complex with proteins and a dipicolinic acid. The complex forms a gel that controls how much water can enter the cell. The only way to destroy endospores is to expose them to steam under pressure which generates temperatures of 121 degrees celsius. An autoclave can create such conditions.
In 1884 the Danish physician Christian Gram developed a new type of stain known today as the gram stain. He attempted to design a stain that differentiated bacterial cells from eukaryotic cells however he failed. What resulted from his work is one of the most important stains in microbiology. The Gram stain is an example of a differential stain. This type of stain takes advantage of the fact that different cells or different structures within cells react differently to various dyes. Gram positive bacteria retain the crystal violet-iodine complex after decoloring with alcohol or acetone and appear purple under the microsope. Gram negative bacteria lose the crystal violet-iodine complex and must be counter-stained with a red dye such as safranin. Gram negative bacteria appear pink under the microscope.