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The difference between a pH reference electrode and a double junction electrode is that the pH reference electrode leaks electrolyte solution , thus you will have to replace the electrolyte solution periodically. People who work out in the field can find this procedure inconvenient and annoying. A pH reference electrode is separated from the external junction through which the electrolyte solution leaks. You must replace the lost electrolyte solution by refilling it through the filling hole. If you work out in the field I don't recommend this electrode for you. There is a side effect to refilling the electrolyte solution , it shortens the life of the electrode due to changes in the electrolyte composition, due to the contamination and diffusional leak of the ions. Contaminated gel cannot be replaced, this then shortens the life of the electrode. Rarely does this type of electrode last longer than several months. The Double Junction electrode is sometimes used to prolong the life of the electrode. There is an extra chamber between the reference electrode and the external solution. Before contamination can reach the reference electrode, it must pass through not just one junction but two, which is where we get the name (Double Junction). The extra chamber acts as a buffer, slowing down the changes in the composition of the reference electrode electrolyte. Double Junction electrodes will last longer and that is why they are often more expensive than your Single Junction electrodes. Single or Double Junction only refers to the way a reference electrode is made. So, make your selection wisely when searching for a pH electrode for your pH meter. You may pay a little more for the Double Junction electrode, but you will have less maintenance and it will last you longer!

Specific Gravity is a measure of the density of a liquid relative to water. Specific gravity measurements are essential to many industries. Wine makers use specific gravity to monitor the fermentation process. These measurements would be taken with a refractometer or hydrometer and be in units of degrees Brix or Baume (Be). Brewers also use refractometers and hydrometers to monitor the change in sugar content of the fermenting wort. Sugar is not the only dissolved solid that is measured by specific gravity. Salt content or salinity is also measured this way. If you have a salt water fish tank at home you probably use a refractometer to determine the saline level. A refractometer measures refractive index. Refractive index is a measure of the speed of light through a substance relative to the speed of light in air. When water has dissolved solids such as salt or sugar this changes the refractive index. Both refractive index and specific gravity are dependent on the temperature of the sample. Specific gravity is also important in the petroleum industry. The petroleum industry uses API gravity (American Petroleum Institute) and ASTM Hydrometers to measure the density of crude oil and petroleum products. HB Instrument Co. manufactures Specific Gravity, Brix , Baume, and API Hydrometers. Kessler produces Baume (Be) hydrometer/thermometers and Nalge Nunc produces polycarbonate salt and specific gravity hydrometers. Reichert and Mettler Toledo are manufacturers of refractometers. So the next time you bid $150.00/barrel on that 1,000,000 barrels of sweet light crude, be sure you have your API hydrometer handy to check the quality.

"I don't have anything to do." How many times have we heard those words (or said them ourselves at 7, remember)? Sure we can park in front of the TV or video game but even that gets old after a while. Microscopes.com may not seem like a toy store to a 7 year old but let's see what we can find. How about that cool green bug, want to see it up close? We can use a magnifying glass of course or we can use our pocket microscope. What about that pretty rock we found that looks like it has diamonds in it, we can look at it with our stereo microscope. What's wriggling around in that puddle of water, or in the pond? Lets put a drop on a slide and get out the microscope and see. There are also prepared slides for our microscope which will show body parts of bugs, people, and animals. Several manufacturers of scientific supplies such as Konus, Carson and Meade make products just for kids. There are tons of alternatives to the TV and the video game, let's explore.

Well, it's that time of year when our 5th and 8th graders will be coming home begging you to help them with their science fair projects; that were handed out to them over a month ago! Isn't that ironic?! It seems that it wasn't that long ago when I had my 5th grade science fair, then my sons just a few years ago when he was just 10 or 11 years old and boy! how times have changed. I did my science fair project on the study of (Crushed Egg Shells & The Benefits of using them in your Garden) My son did his science fair project on (Dissolved Oxygen & The Oxygen Levels in Your Fish Tank), (How to Determine if Low DO is the Cause of a Fish Kill) My project was a bit on the boring side. There were many other projects around mine that involved imagination, creation and the determined assistance of a parent. My Dad worked nights and slept during the day. That is what he had to do to support his family back then. My son was lucky enough to have a mom who worked at a Laboratory Supply Company and could provide him with a lot of assistance. We worked on it together. We purchased 2 goldfish bowls, 2 goldfish, 1 air pump, some tubing, filters, rocks, and fish food. I provided my son with a Dissolved Oxygen meter and a Dissolved Oxygen electrode as well as a temperature meter and general purpose temperature electrode. Dissolved Oxygen (DO) refers to oxygen gas that is dissolved in water. Fish breathe oxygen just like land animals do. Although, fish are able to absorb oxygen directly from water into their blood stream using gills, whereas land animals use their lungs to absorb oxygen from the atmosphere. My son wanted to show how the life of the quality of fish life would differ, one with oxygen added to the water, and the other with no oxygen added. He took 3 (DO) readings a day from each tank, as well as the temperature of each tank. He wrote down his readings for a month, recording the health of the fish along with each (DO) and temperature reading. There are 3 main sources of oxygen in the aquatic environment. 1) direct diffusion from the atmosphere; 2) wind and wave action; and 3) photosynthesis. Oxygen derrived from photosynthesis , is produced during the day when the sun shines on the plants in the water. Oxygen levels drop at night because of plants and animals, including fish. Oxygen depletion refers to low levels of (DO) and may result in fish mortality. The cause of oxygen depleation occurs when oxygen consumption exceeds oxygen production. This can be caused by an overabundance of plant life or alge in the water. All fish die at approximately the same time often during the night or in the early morning hours. Large fish may be more effected more than small fish. When a fish is depleated of oxygen, you may often see him at the surface "gasping" for oxygen. Some fish may die with their backs arched, gills spread and mouth open. The weather immediately following the fish kill may have been very hot, still and overcast. There may have even been a storm prior to the kill. An oxygen depleating event sever enough to result in signifigant fish mortality is often observed in water with heavy populations of algae of aquatic plants. The moral of this story is: to remember that we are in the time where technology is everywhere. Spend time with your children helping them with their school work and enjoy them while they are young. My son is almost 18 years old. Time sure does fly when your having fun!!! Footnotes: The technical information regarding Dissolved Oxygen for fish production is a Fact sheet FA27 one of a series of the Department of Fisheries and Aquaculture, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. First published September 1992. Reviewed: May 1997, Feb 2003. Please visit the EDIS website at http://edis.ifas.ufl.edu

Syringes are not just for the Doctor's office. For instance Popper offers syringes and needles for industrial, laboratory, and veterinary use. These reusable syringes can be ordered in a wide variety of volumes, needle gauges, and needle hub designs. Hamilton offers glass chromatography syringes for autosamplers and gas tight syringes for Gas Chromatography (GC). Agilent also makes glass syringes for these applications. Air-Tite offers plastic syringes for laboratory, industrial, and veterinary use. And of course BD Medical offers a wide array of syringes for medical, industrial, and laboratory use. Microscopes.com is a great place for finding a syringe no matter what your application.

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A lens is a molded piece of glass, plastic or other transparent material with opposite surfaces either or both of which are curved, by means of which light rays are refracted so that they converge or diverge to form an image. A combination of two or more pieces sometimes with other optical devices such as prisms, used to form an image for viewing or photographing. A lens system consisting of two systems combined so that the back focal point of the first ( the objective) coincides with the front focal point of the second (the ocular) is called a telescope. There are many different items that we use on a daily basis that require lenses, eye glasses, sun glasses, goggles, binoculars, telescopes, cameras, microscopes and more! Did you ever think about exactly how many items require lenses? The list could go on. Many different activities require us to use these items in our daily lives. I need glasses to see because I am nearsighted. Some people need glasses because they are farsighted. Some people need bi-focals to see both near and far. Each type of eyeglass takes the same technology to make the specific type of lens, we just tweak it a bit for each style of lens that is required by the patient. Some people like to purchase by brand, and others are not so picky. Some brand name examples are D&G, Bolle, Serengeti, Anne Klein, Puma and the list goes on. What about our dads, brothers, uncles, sons, and grandfathers who like to hunt? They might require a rifle scope to mount to their deer rifle for hunting the white tail deer. What about moms, daughters, aunts and grandmothers who like to Bird Watch? They will need a birding binocular or a birding spotting scope. Bird watching is one of the fastest growing activities today. Anyone can be a birdwatcher, from the young to the old. Microscopes, are used by very knowledgeable research scientists to the young and inquisitive natured. Microscopes are used by parents, to share an early education with a child of what a bug or a plant cell might look like under the scope. Microscopes are used by teachers in the classroom, for the first dissecting lab projects. A Dissecting Microscope or Stereo Microscope would work in both situations. Some brands that would be good for the hobbyist or beginner would be Lomo, Meade, or Nikon. These microscopes will do much more than just dissect. They will provide you with a lifelong time of memories. Whoever you might be, the hunter, birdwatcher, researcher or hobbyist, be sure to do your homework. Research what it is you want to look at. That will determine what type of microscope you will want to purchase. Will you need a glass slide and a stage to set your specimen on? Take everything into consideration before purchasing a microscope. Remember to consult a specialist, if you are not sure which type of microscope you will need. Please don't waste your money on a microscope that will not do the job you expect it to. Cutting corners is not always the best option for all situations!

When some molecules are exposed to the correct wavelength of light they are excited to a higher state, the molecule then drops back down to a normal state and emits light at a lower wavelength. This emission of light, Fluorescence, is a powerful detection tool. Under the right conditions single molecules can even be detected. In an immunoassay an antibody to a protein being studied has a fluorescent molecule attached to it. When the antibodies attach to the protein and are exposed to the correct wavelength of light the whole protein-antibody complex fluoresces and is detected at a very low level. In fluorescence microscopy the specificity of the antibodies makes it possible to study one protein in many different cells or tissues. Using optical filters the only thing the researcher sees through the microscope is the protein of interest.

Hoods, Cabinets, and Glove Boxes at Microscopes.com Researchers very often need to use laboratory enclosures to be protected from their projects. The nature of the experiment itself will determine what kind of enclosure is necessary. A chemical hood (fume hood) is used if the researcher is working with volatile or dangerous chemicals, or the chemical reaction produces dangerous fumes. A ducted hood sends the dangerous fumes to the atmosphere. A recirculating hood filters the fumes from the air and send the air back into the laboratory. A biosafety cabinet is used when the scientist is working with biohazardous material. A level I biosafety cabinet recirculates air in the hood through a HEPA filter. Some of the air stays in the cabinet and some is exhausted into the lab. The air in the hood is carried across the project toward the back of the hood to protect the worker. A level II biosafety cabinet vents the filtered air to the atmosphere. These hoods have glass doors which raise and lower to allow the experiments to be set up in the hood. While the experiment is being conducted there is an optimum height for the glass door which is indicated at the front of the cabinet or hood. There are many times when the project needs to be protected from the researcher or the atmosphere. When performing cell culture (tissue culture) a laminar flow hood is used. This type of enclosure passes air down the front of the hood and out to the room to keep contaminants from entering the cabinet. This is also the case with a PCR cabinet. There are times when a specific atmosphere is required such as research with anaerobic bacteria. In this case an airtight glove box is used along with a vacuum and special inlets to remove oxygen and moisture. In the case of moisture sensitive samples inert gases such as Argon or Nitrogen are used. Special transfer chambers on the side of these glove boxes allow the introduction of test samples without compromising the atmosphere inside. Microscope.com has a large line of Labconco laboratory enclosures to choose from.

A little history on thermometers: Gabriel Fahrenheit invented the first mercury thermometer in 1714. Some history reference books state that Galileo Galilei invented a very imperfectly developed water thermometer in 1593. It was a device that consisted of a long glass tube inverted in a sealed jar that contained both air and water. It is stated that there are no supporting documentation to support his work on this. This is what scientists have found. The true inventor of the thermometer was Santorio Santorii . Santorio first used his thermometer for medical use.His works were published in 1612. He applied a medical scale to his thermoscope which had previously only been used to measure air temperature, to measuring human body temperature, so this became the first thermometer! There are currently many new and updated reasons to use thermometers in the 20th century. Checking a child's temperature, checking the temperature of a candy recipe to make sure it sustains a constant temperature, checking the temperature of a roast that you are cooking to make sure it is just right and not overcooked. In the food Industry, health inspectors used to rely on regular contact thermometers, to monitor critical temperatures. Now we have new technology that allows Food Inspectors to use Infrared thermometers that allow them to just point and shoot at their target. Non-contact thermometers use Infrared laser technology to quickly and safely measure the surface temperature of objects. It is so easy! All you have to do is point from a distance, aim at object or surface that you want to get a temperature reading on, and it appears on the LCD screen on the unit. These units are a great addition to the 20th Century, in that they provide you with a reading within seconds, compared to much longer times when we measured things with manual thermometers. Another great aspect of an infrared thermometer is that they are great for Hazardous Analysis and Critical Control Points. (HACCP) programs, which require general monitoring of food temperatures. Infrared Thermometers are used in all aspects of food handling, processing, preparation storage and safety. Inspectors can monitor processing equipment. Used as a scanning tool they can easily spot potential problem areas. Control Company offers a model that is traceable to NIST (National Institute of Standards and Technology), adjustable emissivity (a measure of a materials ability to absorb and radiate energy), data hold, maximum and minimum memory, and one-second sampling. Next time you want to check the temperature of a pot or the outside of your oven, remember you can use new Infrared Technology by using an Infrared laser thermometer.