Science

Refine Search

What color is terracotta?

Terracotta is a type of ceramic made of baked but unglazed earthenware clay. Earthenware clay contains varying concentrations of iron oxide, which give them their color. By comparison, stoneware clays tend to be white or gray in color because they do not contain iron.The natural shade of terracotta is in the brown and orange range of the color palette; however, dye is sometimes added to bring out deeper hues. For example, scientists discovered that a purple dye had been used on the Xi'an terracotta warrior statues.

Continue Reading

Has a human ever been cloned?

Reproductive cloning involves removing the nucleus from an egg cell and fusing the enucleated egg with another cell taken from the body of the egg donor. This fusion produces an egg cell with a genome identical to the donor. Donor and baby would be as similar as two identical twins, only with very different ages. While the scientific barriers to human cloning are probably surmountable, the ethical implications involved in creating a duplicate of another human being have led many countries around the world to adopt laws prohibiting reproductive human cloning.

Continue Reading

Does water conduct electricity?

Pure water is defined as water that is completely free of any other chemical compounds. Since water is known as a universal solvent, it has the ability to dissolve a large number of compounds. Water found in nature tends to have a large number of dissolved substances. These substances are often organic and are completely safe for consumption. However, they also can conduct electricity, making the water they are dissolved within able to conduct electricity as well.

Continue Reading

What causes water's low vapor pressure?

Hydrogen bonds are much weaker than covalent or ionic bonds, which explains why water molecules do not break apart as easily as they evaporate. Nevertheless, the hydrogen bonds between water molecules cause the molecules to tend to stay in the liquid state. Additionally, the hydrogen bonds cause the surface tension of water to be relatively high.\nThe amount of air pressure over a sample of water influences its vapor pressure and boiling point. For example, if the amount of air pressure over the water is doubled, much fewer water molecules break their bonds and evaporate, resulting in lower va..

Continue Reading

What is the membrane that lines the medullary canal?

There are three different types of endosteum: cortical, osteonal and trabecular. The name of each type refers to the area of the inner bone where it is located. The medullary cavity is the central cavity of bone shafts where red bone marrow and yellow bone marrow are stored. The medullary cavity is also known as the marrow cavity, an area that is a vital component of the body's skeletal system.

Continue Reading

Where can you find information about contaminated rivers?

The above cited sources discuss specific cases while the EPA discusses general causes in an article entitled "Nonpoint Source Pollution." These causes include runoff from construction sites, agricultural chemicals, pesticides and pathogens. Finally, the American Museum of Natural History posted "River Ecology," which captures the dynamics of waterway health in a report on the effects of the invasive zebra mussel on the Hudson River system.

Continue Reading

Why does RNA use uracil instead of thymine?

It is also possible that during early cell development, the preference of RNA for uracil evolved to avoid competition with deoxyribonucleic acid polymerases for thymine, notes the National Science Teachers Association. An examination of RNA synthesis may show that it is more efficient when using uracil than it would be if it used thymine. DNA, which has greater stability than RNA, is able to use thymine efficiently.

Continue Reading

What do prokaryotes and eukaryotes have in common?

A main difference is that eukaryotes have a nucleus while prokaryotes do not. Unlike eukaryotes, prokaryotic organisms do not have membrane-bound organelles within the cell. Eukaryotic cells are much larger than prokaryotic cells. For example, the size of prokaryotic cells can range between 2 and 20 microns while eukaryotic cells range in size from 10 to 100 microns in diameter. In terms of cell division, prokaryotic cells divide through binary fission, and eukaryotic cells divide through the process of mitosis.

Continue Reading

How many electrons are in the third energy level?

The maximum number of electrons on any given level can be determined by the formula two times n squared, where n is equal to the energy level. For the third energy level, the formula is two times three squared. The third energy level contains s, d and p orbitals.\nThe first element to have electrons in the third energy level is sodium, which is the first element in the third row of the periodic table, represented by the symbol Na. Sodium contains one electron in its 4s orbital. The element to its right, magnesium, contains two electrons in the 3s orbital. The next six elements, in the p-block,..

Continue Reading

How do you make flash powder?

Prepare the areaEnsure that the work table is clean, flat and dry. There should be no chance of static shocks. Avoid wearing rubber shoes on synthetic carpets in dry air. Mill the perchlorateMeasure the perchlorate to two-thirds of the size batch. For instance, a batch of 12 grams should contain 8 grams of perchlorate and 4 grams of aluminum powder. Don't mix more than 12 grams with each batch. Place the perchlorate on a sheet of paper, and use the metal roller to mill it into a fine powder. Re-mill the powder if it's lumpy. When finished, pour the powder into the mixing bag. Add the..

Continue Reading
Showing 1301 to 1310 of 10000 (1000 Pages)