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  1. How to Read a Vernier Scale
    April 08, 2021
    Vernier scales can be used on microscopes, stereotaxic frames and micromanipulators. The vernier scale was invented by French mathematician Pierre Vernier in 1631 as an upgrade on Pedro Nunes' measurement system for precision astrolobes. With a main scale and a sliding secondary scale, a vernier is used for making precise measurements.    How a Vernier Scale Works The vernier scale is marked with divisions slightly smaller than the divisions of the main scale. For example, a vernier scale could have 11 markings for every 10 on the main scale. That's 10 divisions on the vernier scale for every 9 on the main scale. This means that the vernier divisions are each 90% of the main scale divisions. In this case, the 0-line and the 10-line on the vernier could pair up with marks on the main scale, but none of the other divisions on the vernier would match a line of the main scale. For example, the 0 and 10-lines of the vernier scale could pair up with the 0 and 9-lines on the main scale. If the 0-line pairs up with a mark, the first division of the vernier (1 mark) would be 10% short of reaching a mark of the main scale, the second division (2 mark) would miss a mark on the main scale by 20%, the third division (3 mark) would miss a mark on the main scale by 30%, etc.   How to Read a Linear Vernier Scale Follow these steps to read the vernier scale: Read the main scale. Look for the last whole increment visible before the 0 (zero) mark. Read the secondary scale (Vernier) measurement. This is the division tick mark that lines up best with a mark on the main scale. Add the two measurements together. The image at the right shows a linear scale. The 0 on the vernier scale lines up with the 4 on the main scale. Notice that the 10 on the vernier scale also lines up with a mark on the main scale (4.9). We ignore the second mark that lines up. So, the measurement shown is 4.00mm. The second
  2. FAQs about Metal Microelectrodes
    April 30, 2019
    Here are some frequently asked questions (FAQ) about Metal Microelectrodes. What metal type is best for my application?W- Tungsten Tungsten is a versatile and widely-used microelectrode material that offers a good balance between performance and cost. ADVANTAGES DISADVANTAGES Extremely strong and stiff metal provides probes with exceptional rigidity. Great for acute and chronic recording due to biocompatibility and lower cost. High corrosion resistance offers consistent long-term performance. Does not provide the same degree of electrochemical performance or stability as platinum-iridium alloy, making it a poor alternative for microstimulation. Lower charge transfer capacity of tungsten will result in larger, potentially
  3. FAQs about TEER Measurement
    February 02, 2015
    Here are some frequently asked questions (FAQ) about TEER measurement using an EVOM2. Are the electrical resistance and transepithelial electrical resistance (TEER) the same thing? What is an EndOhm chamber? How is an EVOM2 used for measuring confluence? Why use an EndOhm instead of a STX? How do I clean my electrode? What about electrode preconditioning? Can you give me a simple data acquisition system for TEER? What are the TEER measurement challenges that I may encounter? Can you suggest some experimental
  4. FAQ: Troubleshooting Unstable Resistance Readings from an ENDOHM
    November 18, 2013
    One of our frequently asked questions (FAQs) concerns TEER measurements with an EndOhm. If the resistance readings from your ENDOHM don't stabilize, you may need to do some troubleshooting. Test the EVOM2 First, test your EVOM2 meter. The 1000Ω test resistor (WPI # 91750) can be used for this purpose.
  5. What's the Difference Between a 3-way and 4-way Stopcock?
    April 26, 2013
    A 4-way stopcock allows for 360° of rotation and has the states (shown below) for each of the four available positions. A 3-way stopcock has only three positions and has the first three states shown below. In the first state, liquid flows between points A and B.In the second, it flows between points A and C.In the third, it flows between points B and C.In the fourth state (4-way only), it flows between all three points.    3-way and 4-way stopcocks are sold in the popular kit 14011. They can also be bought separately: 14035-10
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