"You know how Superman made a diamond by squeezing a piece of coal? Can scientists really do that?" As teachers, we can now honestly answer our student's question, having performed the procedure ourselves. While Superman used coal and Robert Wentorf from The New Alchemists used peanut butter, we used graphite disks. Of course it would have not been possible without Glenn Richard of the Center for High Pressure Research (CHiPR) and their Kennedy Press.
The Center for High Pressure Research is a National Science Foundation Science and Technology Center with facilities located at SUNY Stony Brook, Princeton University and the Carnegie Institution of Washington. Now, the question that comes to mind is "Why do they make diamonds?" and the obvious answer is, "Because they can." According to Glenn Richard, "Theoreticaly, anything with enough carbon can make a diamond... but we'll be using graphite disks." The use of CHiPR's Kennedy Press helps to simulate the temperature and pressure of the Earth's interior; the location where diamonds form naturally. In the Kennedy press, a pressure of 57,000 atmospheres and a temperature of 1300 degrees Celsius was created to mimic the upper mantle (125-250km deep).
The entire process begins with a procedure known as "dressing the cubes." The aforementioned cubes are one inch square tungsten carbide anvils. There are eight anvils in total, each with their corners removed. The missing corners create an octahedral cavity when the anvils are stacked in two layers of four. This octahedral cavity will is the site of the graphite to diamond transformation.
To dress the cubes we first removed the detritus from previous experiments and prepared our own gaskets around the octahedral chamber. The gaskets are made of pyrophyllite and teflon and need to be measured precisely to assure proper application of the extreme pressure to the sample. The sample assembly (approximately .4 cm diameter by 1 cm length) is actually a composite of containers, each made of different materials. The inner layer is the actual sample cup and is composed of magnesium oxide. Surrounding the MgO cup is a graphite furnace, through which an electrical current is passed to obtain the 1300 degree Celcius temperature in the diamond experiment. Finally, surrounding the MgO and the furnace is a sleeve of zirconia. Inside the sample cup a small amount of nickel-manganese catalyst, three graphite disks and an optional seed diamond are placed before being capped and the entire cup inserted into a manganese oxide octahedron.
The entire octahedron assembly is placed in the cavity surrounded by the gaskets. The anvils are taped and fastened together with plastic in order to provide stability until the Kennedy press has started its compression. Attached to two alternate anvils are copper electrodes to conduct the electricity through the sample graphite furnace. The anvil assembly is then placed in the compression chamber of the Kennedy press. The press is sealed and the log book is checked to find the settings of past experiments. The log reveals that a pressure gauge setting of 235 bars will give us the desired 57 kilobars on the sample.
A little more than a pot roast, after ten hours our diamond is ready. Removal of the octahedral assembly from the anvils is easily accomplished with a screwdriver or even your hands. The sample must then be hammered out of the matrix and examined. Sometimes no diamonds form and other times many diamonds form but ideally our experiment was intended to yield one larger diamond. The tests to find if something formed are numerous. The first test is a visual inspection followed by dissecting microscope inspection. In the case of formation when the diamonds are too numerous and too small to identify, an X ray diffractometer can be used. In most cases the proof lies in a scratch test
Now that you have created your diamond you come to the realiztion that your manufactured diamonds have no practical use or value. So it is not yet time to go out and buy that platinum setting. However, manufactured diamond has many scientific uses.
The Pine Barrens of Long Island today represent less than 100,000 acres of land. It is a unique plant and animal community in that it is a fire climax ecosystem, adapted and dependent upon fires to maintain its existence.
The uniqueness of the system is further enhanced by the fact that many of the plants and animal species found in the Pine Barrens are rarely found in most eastern deciduous forests. This fire climax community of plants and animals is directly related to the characteristics and distribution of the glacially deposited sediments that form this part of Long Island. The soils of Long Island can be generally classified according to their glacial origins. The soils of moraines and that of the outwash plains are quite different due to the greater degree of sorting in the outwash plains that were deposited by glacial meltwater. The degree of sorting is going to have a major impact on the porosity and permeability of the soils. Since soils affect plant types, vegetation trends can be correlated to soil types. This is the case in the Pine Barrens. The soils are well sorted sands with good permeability. Since decay is slow, dry leaves accumulate as litter on the ground and provide good fuel for fires. Average fire frequency for the Central Pine Barrens is estimated bny some experts to be 25 years.
The largest stands of Pine Barrens are in central and eastern Brookhaven and encompasses the Terryville outwash plains and portions of the Ronkonkoma Moraine which seems to have the same sandy deposits as the outwash plains. [Figure 5-2 Map LI Water Resources Curriculum Guide]
The Central Pine Barrens is a woodland characterized by dominance of pitch pines. A unique dwarf pitch pine forest, known as the Dwarf Pine Plains, encompasses 2500 acres south of Riverhead, near the Suffolk County Airport in Westhampton. Pines and scrub oak in this area average 4 to 6 feet in height when full grown. These pygmy pines possess serotinous cones which only open in extreme heat. This is an adaptation for survival of the frequent forest fires in this area, which occur more frequently in the Dwarf Pine Plains (about 6-7 year cycle). On August 18, we burned a serotinous cone in the laboratory in order to watch it open.
The purpose of our study was to determine if soil characteristics are different in the Central Pine Barrens and Dwarf Pine Barrens. Differences in soil characteristics, such as sorting and permeability, could be a contributing factor towards increased fire frequency in the Dwarf Pine Plains, leading to dwarfism of its plant community. Our hypothesis was that the Dwarf Pine Plains will have sediments that are better sorted and more permeable. This would constitute better drainage, resulting in drier soils and lower decay rates. The dry soil and accumulation of leaf litter would serve as fuel for fires.
The two goals of our study, therefore, were to:
Our procedure involved the collection of a soil sample at four locations, two in each of the regions. We took our sample from a depth of 15 centimeters.
In the lab, we measured the mass of the sample, and then poured each sample into sieves which were placed in the ro-tap machine in order to sort grain size. After sieving, each grain size component was massed.
To determine the percent grain size, we divided the mass in each sieve by the total mass.
[% Grain Size = mass in sieve/total sample mass x 100%]
After all of the masses are determined a bar graph was constructed to illustrate grain size distribution for the Pine Barrens and Dwarf Pine Plains.
In order to calculate the hydraulic conductivity, first we need to find the effective grain size (d10) graphically. A graph was constructed for each sample of percent finer by mass versus grain size using a logarithmic scale for our grain sizes (4mm, 2mm, 1mm, .5mm, .25mm, ,125mm). The graph was used to determine the effective grain size, which is the size for which 10% is smaller. This is used in the formula to compute hydraulic conductivity. A value of 120, reflecting well-sorted coarse sand, was used for the sorting constant "C".
Hydraulic conductivity (K) = C(d10)2
Soils of the Central Pine Barrens and Dwarf Pine Plains are similar in grain-size distribution, consisting of well-sorted, fine to medium grain sands. There does not appear to be a significant difference in sorting or grain-size distribution between the soils of the Central Pine Plains and Dwarf Pine Plains. In all of the samples, approximately 80% of the sample consisted of grains between 0.25 and 1.0mm.
Hydraulic conductivity was calculated for each sample. In the samples from the Central Pine Barrens, effective grain size was determined to be 0.020cm, resulting in a hydraulic conductivity of 0.048cm/sec. Effective grain size of the Dwarf Pine Plains soils is slightly 0.023cm, resulting in a higher conductivity of 0.063cm/sec.
The soils from the Dwarf Pine Plains and Central Pine Barrens are well sorted, fine to medium grained sands. There is no significant difference in grain size distribution.
Hydraulic conductivity is higher in the Dwarf Pine Plain, which indicates higher permeability. This finding supports our hypothesis that the Dwarf Pine Barrens have better drainage than other parts of the Pine Barrens ecosystem. This could support drier surface conditions that could result in more frequent fires characteristic of this unique dwarf forest community.
William Miller, John Vodicka and Gary Vorwald