Aluminum Manufacturing Process - How is Aluminium Produced?

Like many metals, aluminum is a very useful element.
It is found in rock as bauxite, which is an aluminum ore containing oxygen.
The oxygen has to be removed before the aluminum can be used.
The oxygen and the aluminum are joined so firmly that ordinary smelting does not remove the oxygen as it does with other metals.
The best way to separate the aluminum and the oxygen is to pass electricity through them.
This is called electrolysis.
First of all, rock and sandy particles are removed from the aluminum ore.
This leaves a white powder called aluminum oxide.
It is made up of aluminum atoms joined to oxygen atoms.
The powder is dissolved in a tank of chemicals and heated to about 1742 °F (950 °C).
This makes the aluminum oxide melt and become a liquid.
Molten aluminum collects at the bottom of the tank.
Any impurities in the aluminum collect at the top, where the aluminum oxide cools to form a crust.
Rods made of carbon are lowered into the molten aluminum oxide.
An electric current flows through the molten liquid.
The current enters the liquid through one of the rods and leaves through the carbon lining of the tank.
As this happens, the current breaks up the molten aluminum oxide into aluminum and oxygen.
The molten aluminum metal sinks to the bottom of the tank, and the oxygen combines with the carbon, to be released as carbon dioxide gas.
The pure, molten aluminum is drawn off into a crucible and then poured into molds to cool.
The cool aluminum hardens into ingots.

What are the Primary Colors of Light and What is Color Spectrum?

The colors of the rainbow are red, orange, yellow, green, blue, and violet.
But these are not the only colors in the rainbow.
If you look carefully at a rainbow, you can see that there are colors in between the red and the orange bands that are mixtures of the two.
This is true for all the other main colors as well.
The whole range of these colors is called the spectrum.
The three most important colors of the spectrum are red, green, and blue.
These are the primary colors of light.
All the other colors you can see are mixtures of these three.
If there are equal amounts of red, green, and blue light, you see this mixture as white light.

Colors and wavelength

Try to think of light as something that travels like waves.
White light can be split up into different colors because each color is made up of waves of a particular length. The distance between the top of one wave and the top of the next wave is called the wavelength, and each color has its own wavelength.
The color blue has the shortest wavelength.
Red has the longest wavelength.
When red and green lights are mixed, the result is yellow light.
A mixture of blue and green light forms blue-green light, and blue and red lights form purple light. Combining all three primary colors in light in the proper proportions results in white light.

How much calcium is in human body?

The average human body contains about 1.5 kg of calcium. Major part of the calcium is in the bones as a major part of bone mass.
Bone structure, we could compare with reinforced concrete.
Bone has fibers called collagen fibers, similar to the flexible and iron wires that are placed in reinforced concrete. Calcium makes mass which surrounds the collagen fibers.
The amount of calcium in our bones changes with age. 
During the first year of life the child bones have very little calcium and are very flexible. The child can bend in all sorts of directions without breaking any bones. But when one experiences the age of 80, his bones can contain nearly 80 percent of calcium, and are easily breakable.
To young children we give a lot of milk, among other things, because the milk is very rich in calcium, and young organism is, of course, in need a lot of calcium. One liter of cow's milk contains more than 1.5 g of calcium. Cheese, cream and yogurt also contain large amounts of calcium.
In those parts of the world where the food does not have enough calcium people do not have healthy teeth and often suffer from bone fractures.

What Is Crop Rotation And What Are The Benefits Of Crop Rotation

The land that we need for growing food is very important. We can't afford to spoil it. There are many ways in which farmers could make better use of the land and grow good crops without the help of factory-made chemicals.
If it is farmed with care, the land will go on giving us enough food to eat for thousands of years to come.
One method of careful farming is called crop rotation.
Different kinds of plants take different nutrients from the soil and leave others behind. The same crop planted year after year takes out the same nutrients.
But different crops, like corn and alfalfa, can be planted on the same piece of land.
One year, corn is planted. This will take out certain nutrients from the soil. The following year, alfalfa will be planted. The alfalfa will put back the nutrients absorbed by the corn.

Health Care Careers List - List of Jobs in The Medical Field

Medical specialists are medical professionals who have knowledge, education, and training in a particular field of medicine.
In the following lists are presented some types of medical specialists and their areas of expertise.

List of medical careers

Allergist 

Area of expertise: Treatment of allergies

Anesthesiologist 

Area of expertise: Administration of anesthetics for surgery

Cardiologist 

Area of expertise: Diseases of the heart and circulatory system

Pulmonary Specialist

Area of expertise: Diseases of the lungs and chest

Dermatologist

Area of expertise: Diseases of skin, hair, and nails

Emergency Medicine Specialist

Area of expertise: Emergency treatment of acute illnesses and injuries

Epidemiologist

Area of expertise: Causes, transmission, and control of infectious diseases

Family Physician

Area of expertise: Ongoing health care for persons of all ages

Gastroenterologist

Area of expertise: Diseases of the digestive system

General Surgeon

Area of expertise: Surgical treatment of diseases of the abdomen, breast, and other areas

Gynecologist

Area of expertise: Diseases of the female reproductive organs

Hematologist

Area of expertise: Diseases of the blood, bone marrow, and lymph tissues

Internist

Area of expertise: Nonsurgical treatment of diseases of the internal organs

Nephrologist

Area of expertise: Diseases of the kidney

Neurologist

Area of expertise: Diseases of the brain and nervous system

Neurosurgeon

Area of expertise: Surgical treatment of diseases of the brain and spinal cord 

Obstetrician

Area of expertise: Health care for pregnancy, labor, and childbirth

Oncologist 

Area of expertise: Treatment of cancer

Ophthalmologist

Area of expertise: Diseases of the eye

Orthopedist 

Area of expertise: Diseases of the bones, joints, and muscles

Otolaryngologist 

Area of expertise: Diseases of the ear, nose, throat, and neck

Pathologist

Area of expertise: Study of biopsy specimens and body fluids

Pediatrician

Area of expertise: Health care of infants, children, and adolescents

Physiatrist 

Area of expertise: Rehabilitation of patients following illness or injury

Plastic Surgeon

Area of expertise: Cosmetic surgery and surgical reconstruction

Podiatrist

Area of expertise: Disorders of the foot

Proctologist

Area of expertise: Diseases of the anus, rectum, and colon

Psychiatrist

Area of expertise: Treatment of mental disorders

Radiologist

Area of expertise: Study of X ray and ultrasound

Rheumatologist

Area of expertise: Treatment of rheumatic diseases

Urologist

Area of expertise: Diseases of the urinary tract and the male reproductive organs

Vascular Surgeon

Area of expertise: Surgical treatment of diseases of blood vessels


What is Tallying? - Tallying and Tally Marks

Can you imagine a time when people did not use numbers?
The first people on earth lived by hunting wild animals and collecting wild fruit and nuts.
They had no need to count.
Numbers did not matter to them.
But then, about 11,000 years ago, herdsmen began to keep flocks of sheep and goats.
They had to be able to count so that they would know if any of their animals were missing.
The first calculations were made by counting in ones—'1 and 1 and 1,' and soon.

This method of counting is called tallying. 

One way herdsmen used to tally was to put a stone on a pile for each animal.
Other ways were to tie knots in a length of rope, cut notches in sticks, or make scratches on a rock. Each stone, knot, notch, or scratch represented one sheep or goat.


Space Probes Information - Voyager 1 and Voyager 2 - Voyage of discovery

On August 20, 1977, Voyager 2 was launched into space.
Two weeks later, Voyager 1 set off. 

The two Voyagers were types of unmanned spacecraft called space probes.
Their mission was to travel to the more distant planets of the solar system and send information about them back to earth.
No spacecraft had ever traveled so far into space before.
Voyagers 1 and 2 each carried 11 instruments. 
These included remote-controlled computers, television cameras, ray detectors, infrared and ultraviolet sensors, and a magnetometer.
These instruments recorded and sent back information about our solar system.
Technology has developed quickly since the Voyager probes were launched. That equipment is now out of date. A modern, desktop computer is more powerful than the Voyager computers. Scientists have updated the probes' computer programs and made repairs from earth by remote control.
In 1980, three years after its launch, Voyager 1 reached Titan, Saturn's largest moon.
The probe sent back information to earth. It found chemicals like those on earth. But Titan is too cold for these chemicals to develop into living things as they have done on earth.

The journey of Voyager 2

1. On August 20, 1977, Voyager 2 was launched from earth at a speed of just over 24,800 miles (40,000 kilometers) per hour. The idea was to use the gravity, or pull, of each planet it passed to catapult the space probe faster and faster through space, from one planet to the next.
2. On July 9 1979, Voyager 2 came closest to Jupiter and discovered it has three more moons. The planet’s gravitational pull increased the speed of Voyager 2 to around 30.700 miles (48.000 kilometers) per hour.
3. It was August 25, 1981, and Voyager 2 passed Saturn at a speed of 33,700 miles (54,400 kilometers) per hour. Then we learned that Saturn has nine more moons that it was known to have.
4. At Uranus, on January 24, 1986, Voyager 2 discovered 10 new moons. Its speed was now 36,700 miles (59,200 kilometers) per hour.
5. Mission completed! On August 25, 1989, Voyager 2 passed within 3,000 miles (4,800 kilometers) of Neptune's cloud top.
We learned that this planet is a hostile world.
No living thing could survive here.
Twelve years after it left Earth, Voyager 2 reached Neptune. It had traveled nearly 4.4 billion miles (7.1 billion kilometers) and arrived four minutes early!
Voyager 2 carries its own message—a record of voices and other sounds from earth— just in case there is life beyond our solar system.
Voyager 2 is expected to enter interstellar space within a few years of 2016. It is not headed toward any particular star, although in roughly 40,000 years it should pass 1.7 light-years (9.7 trillion miles) from the star Ross 248.
Voyager 2 is expected to keep transmitting weak radio messages until at least 2025, over 48 years after it was launched.

What is a Space Probe? - Information on Space Probes

Until now, human beings have traveled into space only as far as the moon, about 236,000 miles (380,000 kilometers) away.
But robot space crafts are sent very much farther.
These have visited the distant planets.
These robot space crafts are called space probes.

What is a Space Probe?

Space probes carry cameras and many kinds of instruments to study the planets they visit. They send information back to earth by radio.
Probes must be launched from the earth at a very great speed—more than 24,800 miles (40,000 kilometers) an hour.
Then they can escape from the earth's gravity.
Aiming the probe is very difficult, because the planet it must reach is always moving. The probe must be aimed so that it reaches a point in space almost at the same time as its target. It must do this after a journey of many millions of miles, lasting for years.

Voyager space probes

It is an astonishing fact that most probes sent to the planets have reached their targets. In 1989, the American probe Voyager 2 flew past the planet Neptune almost exactly on time, after a 12-year journey. The planet was nearly 3.1 billion miles (5 billion kilometers) away from earth at the time. From this distance, the radio waves from Voyager took over four hours to reach the earth.
A Voyager probe photographed Saturn on its journey into the outer solar system. It used nuclear generators to make electricity.
Solar cells couldn’t be used because sunlight is too weak near Saturn.

Venera space probe

Most probes study a planet as they fly past it. But some actually land on the planet and report back from its surface.
A Russian probe, called Venera, was the first to land on a planet. It parachuted down to Venus in 1970. Since then, several Venera probes have sent back pictures of its surface.
Two American Viking probes landed on Mars in 1976. They sent back pictures and reported on the Martian weather. They also examined the soil for signs of life—but didn't find any!

What is the Function of the Kidneys and How do Kidneys Work?

The kidney filters body fluids within the nephron units and expels wastes via the ureter.


Kidney is one of a pair of organs located at the back of the abdomen, against the strong muscles next to the spine, and behind the intestines and other organs.
The adrenal glands lie on top of the kidneys.
Each kidney weighs about 5 ounces (140g) and is about 4 inches (10cm) long in the average adult.
Its inner structure, which is called the renal pelvis, collects urine as it is formed and passes it out of the kidney to the bladder via the ureter.
The renal pelvis also is connected to the artery and vein that carry blood to and from the kidney.

What is the function of the Kidneys?

The kidneys filter out water and also unwanted substances in the blood.
These substances are produced by the normal working of the body.
They are excreted by the kidneys in the form of urine.
The kidneys also keep the salts and water of the body in correct balance.

How do kidneys work?

The blood passes through each kidney under high pressure.
The blood is filtered by the glomeruli, special structures in the kidney containing clusters of capillaries that collect water, salts, and unwanted substances.
The filtrate passes along a fine tube, the nephron (of which there are approximately one million in each kidney), which reabsorbs any of the water, glucose, and salts that the body still re-quires and allows the rest to pass into the pelvis of the kidney as urine.

Keratitis Definition – What causes Keratitis?

What is Keratitis?

Keratitis is an inflammation of the cornea, the transparent membrane that forms the front of the eye. If the condition occurs suddenly, it causes pain, sensitivity to light (photophobia), and watering of the eye. If atitis develops gradually, only minor discomfort may result.
Opaque patches in the cornea can cause the patient vision to blur.

What causes keratitis?

Keratitis is often a symptom of more general disorder. Virus infections, such as trachoma (chronic conjunctivitis) or herpes simplex may infect the cornea.
Bacteria infection may follow any eye wound.
Keratitis is also a consequence of congenital syphilis or, rarely, tuberculosis.
It most often occurs in children between the ages of 5 and 15.
A deficiency of vitamin A causes dryness of the cornea, which makes it more susceptible to infection.

Keratitis Treatment

Further damage to the cornea can be prevented with eye drops, containing the drug atropine, to dilate the pupil.
Corticosteroid drugs reduce the inflammation.
It is essential for the eyes to be examined by an ophthalmologist.

Kaposi’s Sarcoma Definition - What is Kaposi’s Sarcoma?

Kaposi’s Sarcoma is a malignant tumor, which usually begins as soft, purplish, raised lesions on the feet and spreads through the lymphatic system.
Before 1980, this tumor was seen only in elderly Italian or Jewish men or in younger people from equatorial Africa.
It was a relatively rare disease.
Now, however, a specific, more severe form of Kaposi’s sarcoma (KS), associated with Acquired Immune Deficiency Syndrome (AIDS), has reached epidemic proportions in the United States and several other countries.
The treatment for the milder form of KS is electron beam radiotherapy, while deeper lesions are treated using X-ray therapy.
The more severe type of KS is sometimes treated with antimicrobial drugs and other forms of treatment to help re-store the immune system within the cells.

Albinism Definition - What is Albinism and What Causes Albinism?

Albinism is the lack of brown pigment - melanin, and a person with such property is called albino. The appearance of albinism can also be found in Africa.
Albinism may be partly inherited. Many people are not albinos, but passed the traits of albinism to their children.

What causes albinism?

The color of the skin, hair, eyes, etc.. in humans is the result of the interaction of various substances in the body.
One are the substances that form the basis of future color, and other are the enzymes that act on that basis.
If someone doesn’t has one of these two substances, or their relationship is disturbed, the result is albinism.
The name derives from the Latin word albus, meaning white.

Albinism symptoms

Albinos have pink eyes, because the red blood in the retina of the eye.
Albinos eyes are very sensitive to light. That's why they keep flashing and keep partially lowered eyelids.
Hair and body hair of Albinos are white.
Even the tissues in the body are white, such as brain and spinal cord.

Albinism exists not only in humans but also in animals of all species. 
It was also found in birds.
Albinos are probably white mice, rats and rabbits, which we all know. There are people who have seen albinos squirrel and even a giraffe albino!