MicroscopesBlog: Expert's reviews, news, notes on Microscopes, Centrifuges, Lab Coats, Pipettes, Lab Safety, & more Lab Products!

Hello to all the brew masters of the world! Let me introduce you to your best friend, the Alcohol Hydrometer. An Alcohol Hydrometer is used to measure the strengths of spirits based on the percentage of alcohol by volume at 20° Celcius. This is an uncomplicated instrument made of blown weighted glass. The Alcohol Hydrometer allows brewers to calculate the specific gravity of their alcohol throughout the brewing process, which is of fundamental importance to the final product. Although a Hydrometer is simple enough in theory, however, it requires subtle and careful application to ensure accurate readings. A sample of the spirit is poured into the Hydrometer Jar and stirred with the thermometer. After your sample has settled the Hydrometer is inserted and allowed to float. The temperature reading and Hydrometer reading are taken and the results compared to the chart which will provide the strength in % alcohol by volume. The chart is suitable for all spirits such as, gin, vodka, and whisky whose alcohol content is not obscured by a high level of sugar, caramel, or other solids. VWR and Nalge Nunc are two brands that carry the Alcohol Hydrometer and Hydrometer Jars.

If you look at the top right side of the Objective you can see the Nosepiece Mounting Thread, all Mounting Threads should be sized according to the Standards of the Royal Microscopical Society (RMS) for universal compatibility. Aberration Correction is (APO) (apochromatic) for the highest degree of correction for spherical and chromatic aberrations. Numerical Aperture is a critical value that indicates the light acceptance angle, which determines the light gathering power the resolving power and the depth of field of the objective. Immersion Medium, an immersion medium is a special oil with a refractive index of 1.51. You would use this oil medium as one way to attain higher working numerical apertures. Working Distance, This is the distance between the objective front lens and the top of the cover glass when the specimen is in focus. Magnification Color Code, Microscope manufacturers label their objectives with color codes to help in rapid identification of the magnification and any specialized immersion media requirements. Spring Loaded Retraction Stopper, The plan apochromat objective illustrated in the photo has a spring-loaded front lens to prevent damage when the objective is accidentally driven onto the surface of a microscope slide.

RCF RPM? I often get the question "What is the maximum RCF (or g) for these 50 ml centrifuge tubes?" I also get the question "What is the maximum RPM for these 50 ml centrifuge tubes?" The first question is answerable, the second question requires more information. RPM stands for revolutions per minute and is a unit describing how fast a centrifuge rotor or a wheel is spinning. Relative centrifugal force is the acceleration applied to a sample in a centrifuge and is expressed as RCF. Times one earth gravity is the unit for RCF, or "x g". RCF is dependent upon RPM and upon the distance between the sample and the center of the centrifuge rotor (rotational axis). The formula is: Where r is the rotational axis in cm and N is the rotation speed in RPM, centrifuge RPM. So the question about maximum RPM would depend upon how far away the sample is from the center of the rotor. It is important to know the maximum RCF for a centrifuge tube. Unless the tube is perfectly supported in the rotor there will be stresses which will deform or even crack the tube at accelerations beyond maximum RCF.

Cuvette is a term used for the cell which holds the sample in a spectrophotomer. Sometimes the term cuvet is also used. The standard cuvette is 10mm square, about 45mm tall and made of either glass, plastic or quartz. Glass cuvettes are for visible spectrophotometry. Plastic cuvettes can be either for visible or both ultraviolet and visible depending on the type of plastic used. Quartz cuvettes are for UV spectrophotometry. Most spectrophotomer cuvettes are clear on 2 sides and frosted on two sides for handling. If fluorescence measurements are needed a cuvette must be clear on all four sides as fluorescence is detected at right angles to the beam path. If very precise absorbance measurements are required optically matched cells are used for reference and sample. For less precise measurements 1cm glass test tubes can be used. Path length is the distance the spectrophotometer beam passes through the sample. Most cuvettes have a 10mm path length. For samples with very low absorbance long path length cells are used with path lengths of of 20, 30, 50, or even 100mm. For very small volumes a micro cuvette is used. These have volumes of as low as 50ul while maintaining a 10mm optical path length. Flowcells are also available. These are cuvettes where the absorbance can be measured in dynamic systems such as flow injection analysis.

Lets explore the characteristics of a microscope objective. Everything that you need to know about a microscope objective should be visible to you on the outer housing of the objective as seen in the illustration. The illustration is of a standard 60X plan apochromat objective. It contains common markings that include all of the specifications necessary to determine what the objective is designed for and the circumstances necessary for proper use. I am going to list the identifiers for you for easy reference. Manufacture, the name of the manufacture will almost always be marked on the outside of the objective. Flat Field Correction, in this example it is (Plan). A Plan Objective is one that produces a flat field across the entire field of view. Lateral Magnification in the apochromat objective is 60X; however there are objectives ranging from 0.5x to 250x with many sizes in between. Specialized Optical Properties, in this example referred to as DIC (Differential Interference Contrast) is a is a beam-shearing interference system in which the reference beam is sheared off by a very tiny amount. Tube Length, This is the length of the microscope body tube between the nosepiece opening, where the objective is mounted, and the top edge of the observation tubes where the oculars (eyepieces) are inserted. Cover slip Thickness, the thickness of these small glass plates is now standardized at 0.17 mm for most applications, although there is often some variation in thickness within a batch of cover slips. The majority of transmitted light objectives are designed to image specimens that are covered by a cover glass or cover slip. See PART 2 Right Side Objective Recognition Published Tuesday 8-18-09

Molecular Biology is the study of biology at a molecular level. The field overlaps with other areas of biology and chemistry, particularly genetics and biochemistry. This specific field overlaps with other areas of biology and chemistry particularly genetics and biochemistry. Molecular biology chiefly concerns itself with understanding the interactions between the various systems of a cell, including the interactions between DNA, RNA and protein biosynthesis as well as learning how these interactions are regulated. For this there are more than several techniques of molecular biology; Gel Electrophoresis, Macromolecule blotting, PCR, Arrays, Antiquated Technologies as well as several others. There are specific Molecular Biology Reagents that you may need depending on your technique, for cell culture you may need a dehydrated media. If you are working on a statistical study of blood glucose then you might want to use ION specific test strips by JT Baker.