Frequently Asked Questions
The EM Lab staff will prepare samples for scanning electron microscopy, transmission electron microscopy and some light microscopy. We also provide training to individual users in the operation of the TEM, SEM and light microscopes. The EM Lab staff is available for technical and scientific consultation. We do not teach preparation or ultramicrotomy. Ultramicrotomes are available. We do not have diamond knives for our recharge customers.
Users are charged per hour for equipment time, technical time, and consultation. This is a recharge facility. For U.C. Davis users, a current recharge or DAFIS account number must be supplied so billing can be accomplished. For all other users, a billing address, contact person, phone number and tax ID # are necessary. Accounts are billed monthly unless other arrangements are made. The EM Lab stocks a wide range of supplies in small amounts that can be purchased at cost. To see a list of our services/supplies, follow this link to Rates.
If you would like to receive training on one of our microscopes, please contact our lab staff directly by phone (530-752-3165 or 530-752-4701) or by email. Equipment training is carried out using the researchers own sample.
Training is on an individual basis and usually takes 1-2 hours depending on your competency. Users are charged for beam time on the instrument plus technical time for the duration of the training.
You will need to supply your samples. Proper collection and storage of the sample prior to submission is essential. All other materials will be supplied by the EM lab. Image retrieval can be facilitated by using a USB drive. Highly specialized supplies will be the responsibility of the researcher. Most samples do not require any supplementary materials.
No. We do not allow non-staff to process their samples in the EM Lab. We will be happy to process your samples for you or provide you with protocols. Most reagents are available for recharge purchase from us.
This will be dependent on the type and number of samples you intend to analyze and our work load. Turnaround of one month is not unusual. Every effort will be made to complete your job in a timely manner.
To reserve an instrument on our paper sign-up sheet (not yet available on-line), you may sign up for yourself, contact one of the lab staff by phone (530-752-4701), or email.
It is accurate for most purposes. If you need a high degree of accuracy, we ask you to check it using one of our calibration standards (e.g. cross-grating replica or silicon carbide in the case of TEM or e.g. latex spheres or NIST-approved calibration specimens in the case of SEM). Various calibration standards are available for SEM and you may wish to discuss which to choose with an EM Lab staff member. Please read our disclaimer regarding magnification.
A Transmission Electron Microscope (TEM) is a very powerful magnifying tool. A TEM works very much like a light microscope, except a beam of electrons penetrates a sample instead of light. With an electron beam, images of higher magnification and resolution can be achieved because the wavelength is much shorter than light. This permits up to 1,000 times greater magnification and resolution of images than the best light microscope. The FEI CM120 and the Philips 400G in our facility have practical magnification up to 200,000 times. The image can be viewed on the screen, recorded on photographic films, or digitally captured for analysis. For details about our TEM microscopes, see Equipment.
A Scanning Electron Microscope (SEM) is a very useful tool with applications in various fields. A SEM uses a fine beam of electrons to scan the surface of a specimen. The secondary electrons are then collected by a detector and processed to form images on a monitor for visualization. The FEI XL30 Scanning Electron Microscope in our facility has a practical magnification maximum of 50,000 times. The user can perform conventional SEM (signals from secondary electrons) and backscatter microscopy (signal from backscattered electrons). Images can be captured on photographic films or with a digital imaging system. For details about the FEI XL30 see Equipment.
The samples are fixed and then dehydrated gradually to 100% acetone or ethanol. Then they are either critical point dried (CPD) or dried chemically. Samples must be mounted on a stub and coated with a thin layer of gold in a sputter coater. Samples that are naturally dehydrated can be coated and viewed immediately.
Biological samples for TEM are usually embedded in resin. At least two fixation steps and dehydration precede embedding. The process of embedding takes a minimum of one day. Ultra-thin sections are cut using a diamond knife. Sections are mounted on a grid. After treating the sections with heavy metals the prepared sections are viewed in the microscope. Imaging is accomplished by the electron beam passing through the ultra thin section.. The areas with higher concentrations of heavy metal stains appear electron-dense (darker) compared to the areas with lower concentration of stain, thus creating contrast in the image. Particulate samples can be prepared by a process called negative staining. The preparation time for negative staining is approximately 30 min.
|TEM manufactured in Eindhoven, The Netherlands||FEI||CM120 Biotwin||Hillsboro, OR|
|BioScan 1K x 1K Camera||Gatan||792||Pleasanton, CA|
|MegaScan 2K x 2K Camera||Gatan||794/20||Pleasanton, CA|
|SEM manufactured in Eindhoven,
|Critical Point Dryer||Tousimis||931.GL Samdri||Rockville, MD|
|Sputter Coater||Ted Pella, Inc.||SC-7||Redding, CA|
|Ultramicrotome||Leica||Ultracut UCT||Vienna, Austria|
|Diamond Knife||Diatome, Electron Microscopy Sciences||Ultra 45||Fort Washington, PA|
|Microwave||Ted Pella, Inc.||BioWave 34700||Redding, CA|
|Microwave||Ted Pella, Inc.||BioWave Pro||Redding, CA|
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