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    Platter Substrate Materials

    The magnetic patterns that comprise your data are recorded in a very thin media layer on the surfaces of the hard disk's platters; the bulk of the material of the platter is called the substrate and does nothing but support the media layer. To be suitable, a substrate material must be rigid, easy to work with, lightweight, stable, magnetically inert, inexpensive and readily available. The most commonly used material for making platters has traditionally been an aluminum alloy, which meets all of these criteria.

    Due to the way the platters spin with the read/write heads floating just above them, the platters must be extremely smooth and flat. With older, slower spindle drives and relatively high fly heights, the uniformity of the platter surface was less of an issue. Now, as technology advances, the gap between the heads and the platter is decreasing, and the speed that the platters spin at is increasing, creating more demands on the platter material itself. Uneven platter surfaces on hard disks running at faster speeds with heads closer to the surface are more apt to lead to head crashes. For this reason many drive makers began several years ago to look at alternatives to aluminum, such as glass, glass composites, and magnesium alloys.

    Hard disk platters are very smooth, right? Well, not to a scanning electron microscope!
    The image on the left is of the surface of an aluminum alloy platter; the one on the right
    is a glass platter. The images speak for themselves. The scale is in microns..

    Composed from two original images © IBM Corporation
    Images used with permission.



      Welcome to the information site for one of the world's greatest vocal groups ... The Platters! Since the 1950s, The Platters have undergone a myriad of changes, changes in which have, at times, made this group difficult to keep track of, understand personnel changes, and find accurate and truthful information on. This site is intended to tell the story of The Platters... a story of classic hits, world fame, and success. This site will also present the other side to the story: group division, legal battles, and ugly lawsuits. Most importantly, using personal testaments from many involved with the group such as management, and the members themselves, The Platters Information Site hopes to tell these stories in an honest and truthful manner!


        Good morning DS23
        Trust that you are fighting fit this morning?
        Confusion is a natural state of being


          ASSET PROTECTION is the concept of protecting and preserving one’s assets from frivolous, illogical, ill motivated, devastating, catastrophic claims against your wealth designed to destroy your "current" and "future" lifestyle.

          Let me put it another way: Up to now, you've probably worked very hard to get where you are. But my guess is that you've worked too hard, endured too much stress ... and for what? It can all evaporate before your very eyes.

          The UGLY, UGLY, TRUTH: the fastest growing businesses in America are armies of contingent fee lawyers. (80% of total world's lawyers are in the United States; 130,000 new students are currently attending law school)

          ... Do you remember the woman who was awarded $2.3 million in a suit against McDonald's because "she" spilled hot coffee all over herself. (The Award was later reduced but not eliminated).



            e·vap·o·rate (ĭ-văp'ə-rāt')

            v., -rat·ed, -rat·ing, -rates.


            To convert or change into a vapor.
            To draw off in the form of vapor.
            To draw moisture from, as by heating, leaving only the dry solid portion.
            To deposit (a metal) on a substrate by vacuum sublimation.

            To change into vapor.
            To pass off in or as vapor.
            To produce vapor.
            To disappear; vanish: Our fears at last evaporated. See synonyms at disappear.


              Fun dry ice projects
              Solid carbon dioxide, commonly known as 'dry ice', can be a fascinating substance to study through experiments or fun science projects.

              As most of us can still recall from our science lab days, matter exists in three states: solid, liquid and gaseous. In fact the same substance can exist in all three states, if the conditions are right. The most common example used is water, which can be a solid when frozen, a liquid at most temperatures and a gas once it reaches the boiling point.

              But there is another substance we can obtain readily from an ice house or packing plant that also can exist in different forms- solid carbon dioxide, better known as dry ice. This unusual and fascinating material serves several useful purposes as a freezing agent and food preserver, but can also be the focus of many experiments and fun projects. If you can obtain a supply of dry ice and the safety equipment necessary to handle it (heavy gloves, eye protection, tongs), here are some very interesting experiments you and your children can try at home.

              1. Smashing dry ice with a hammer. This little experiment can explain the transformation of matter from one state to another. Explain to your child that dry ice is a solid form of carbon dioxide, which is usually found in gas form. Take a small portion of dry ice and place it on a very firm surface, like a concrete slab or flat stone. Explain to your child that sometimes solids change into gases without going through a liquid stage. Strike the piece of dry ice with a hammer and see what happens next.

              2. Freezing objects far below 32 degrees Fahrenheit. This is a popular experiment with children, because of the spectacular and largely unexpected results. Explain to your child that dry ice is much colder than the ice cubes in the freezer at home. Frozen carbon dioxide doesn't reach Absolute Zero, which is the coldest any object can get, but it does come fairly close.

              Take some common household items such as flowers, fruits, rubber balls, balloons, or whatever you find that can withstand freezing. Place these objects in an insulated cooler filled with dry ice, and leave them undisturbed for several hours.

              Wearing eye protection and heavy gloves, carefully use tongs to remove the items one at a time for inspection. Ask your child what he or she thinks might happen if you strike the object against a hard surface. After your child has offered his opinion, forcefully strike the various objects on a hard surface, making sure that everyone is at a safe distance. Compare the results with your child's predictions.

              3. Balloons that inflate themselves. Place a small amount of dry ice inside a latex balloon and tie it securely. As the solid begins to turn into gas, the balloon will inflate by itself.

              4. Homemade fire extinguishers. You can explain the heaviness of carbon dioxide gas by setting up this experiment. Place a candle inside a pyrex glass measuring cup. Use a small birthday candle, and sand to hold it upright. In another container place some dry ice in some water to create fog. Light the candle. Carefully 'pour' the fog over the candle, making sure not to spill any actual liquid. Explain to your child that the gas in the fog is heavier than air, so it wants to sink into the glass. When the gas reaches the candle flame, it chokes out the oxygen that the candle needs for fire. The candle goes out. This is the same thing that some fire extinguisher do to put out fires- they make carbon dioxide gas that smothers out the oxygen a fire needs to burn.

              5. Create an entire room of fog. No Halloween party would be complete without a spooky atmosphere filled with fog. Obtain several large tubs that will hold water, and place a substantial amount of dry ice in each just before the party. Make sure the room has plenty of ventilation. Within minutes, your room should fill up with rivers of fog, which will add just the right amount of atmosphere to a haunted house party.


                Home made fire extinguisher
                Most people have fire extinguishers in their homes and in fact, we even place extra ones in the garage where Dad hangs out. All schools and businesses are required by law to have fire extinguishers on their premises. Fire extinguishers work by removing one of the critical ingredients for a fire - oxygen (a colorless, odorless, tasteless gas that is the most plentiful element in the Earth's crust. It was discovered in 1772 by Swidish chemist Carl Wilhelm Scheele.) . In this experiment we demonstrate this process.

                Fill the small dish with baking soda.
                Place a short candle and a slightly longer candle upright in the baking soda
                Place the dish into the bottom of the large bowl.
                Have Mom or Dad light both candles. If Dad's handling the matches then go get that fire extinguisher out of the garage first.
                Pour the vinegar into the dish of baking soda (not on the candles).
                What happens to the candles? Which candle goes out first - the shorter one or the taller one?

                When vinegar is combined with baking soda, the two react and produce carbon dioxide gas. The carbon dioxide gas is heavier than the surrounding air so it sinks into the bottom of the bowl. As the reaction continues, more and more carbon dioxide gas is produced which begins to slowly fill up the bowl. When the level of carbon dioxide has risen to the level of the flame, the flame will go out from lack of air.

                Parent's Note. Fire is the heat and light that comes from burning substances. In 1777, Antoine Lavoisier, a French chemist, proved that burning is the result of the rapid union of oxygen with other substances. As a substance burns, heat and light are produced.

                Carbon dioxide is a colorless, odorless gas. It occurs in the atmospheres of many planets, including that of the earth. On the earth, all green plants must get carbon dioxide from the atmosphere to live and grow. Animals produce the gas when their bodies convert food into energy and living tissue. Animals release carbon dioxide into the atmosphere. Carbon dioxide is also created by the burning of any substance that contains carbon. Such substances include coal, gasoline, and wood. Fermentation and the decay of plants and animals also produce carbon dioxide. Carbon dioxide makes up less than 1 per cent of the earth's atmosphere.



                  yup. diver? don't you ever sleep?


                    Stem Plant decay


                    To: Aquatic-Plants at actwin_com
                    Subject: Stem Plant decay
                    From: Marty Durkin <durkin at stsci_edu>
                    Date: Thu, 25 Jul 96 11:47:43 EDT


                    I have a rather heavily planted 55 gallon tank with a ph of 7.0, kh of 2
                    and gh of 6. I have been using a DIY C02 injection system for about 2
                    months now via an airstone. For about the first month the plants were
                    doing extremely well. As a matter of fact, the Hygro, Foxtail, and
                    watersprite were growing many inches a week. However, for the past
                    2 weeks I have noticed that the Hygro, Foxtail, and Tropic Sunset
                    have started to decay wherever they were snipped and at the base of
                    the stem. There are even cases where they were rotting in the middle
                    of the stem. I removed the bands around the stems when I planted them.

                    Could this rotting be caused by a lack of fertilization. I have only been
                    putting about 2 cap fulls of ferovite in the tank once every three weeks
                    because I was having a problem with thread algae. Also, I have been
                    doing 30% weekly water changes. Is this too much?

                    Thanks in advance for any advice.



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                      TROPIC SUNSET COLOR
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                      Night scene on tropical beach illustration poster

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