ATOMS ARE THE SMALLEST INDIVIDUAL parts of an element.They are tiny, with diameters in the order of one ten-thousand millionth of a meter .Two or more atoms join together to form molecule of a substance known as a compound,for example ,when atoms of elements hydrogen and fluorine join together ,they form a molecule of the compound hydrogen fluoride .So molecules are are the smallest individual part of a compound. Atoms themselves are not indivisible- they possess an internal structure .At their centre is a dense Nucleus , consisting of protons, which have a positive electric charge, and neutrons, which are uncharged .Around the nucleus are the negatively charged electrons .It is the electrons that gives a substance most of its physical and chemical properties.They do not follow a definite paths around the nucleus.Instead , elect
Posts
FOR THE first time scientist led by an Indian -origin researcher have successfully replaced a major blood vessel in a 10 year old girl with a vein grown in a lab using her own stem cells. The pioneering transplant publish in The Lancet, marks a further advance in growing body parts in laboratory. and offer hopes for patients who lack suitable veins for dialysis or by pass surgery.In the landmark research,a team from the University of the Gothenburg in sweden took a vein from a dead man ,stripped of its own cells and then bathed in stem cell from the girl,who was suffering from portal vein obstruction. There was a " striking " improvement in her quality of life after the transplantation,Professor Suchitra The hepatic portal vein drains the blood from the intestines and spleen to the lever.The blockage can cause serious c
MODERN JETLINERS HAVE ENABLED ordinary people to travel to places where once only the wealthy could afford to go .Compared with the first jetliners (which were introduced in 1940's) Modern ones, are much quieter ,burn fuel more efficiently, and produced less air pollution.These advances are largely due to the replacement of turbojet engines with turbofan engines.The greater power of turbofan engines at low speed enable modern jetliners to carry more fuel and passengers than turbojet aircraft;a modern boeing 747-400 (known as jumbo jet) can fly 400,people13,700 km(8500 miles)without needing to refuel.Jetliners fly at a high altitudes ,typically cruising at 8,000-11,000m(26,000-36,000ft),where they can use fuel efficiently and avoid bad weather.The pilot always control the aircraft during take-off and landing,but at other times
SINCE MOTORING BEGINS racing cars have been a major focus of innovation in car design .Features that are now commonplace such as disc brakes turbocharger and even safety belts were used on competition cars.Research into racing cars has contributed to a new understanding of engine performance,aerodynamics and Tyre adhesion,and has led to the development of ultra- light materials such as carbon fiber for car bodies.Like the 1937 Bugatti type 57s , a modern Williams formula One car has a low streamlined body and an open cockpit ,but unlike its forerunner ,it also has a front wing that pushes the front wheels firmly on to the track.,huge slick tires fit extra grip, and electrical sensors that continually relay information to the pits about the car's performance. RACING CARS .BUGATTI,57S
CD -ROM IS A TYPE OF COMPUTER DISC (CD) that can be used to produced images on a computer screen.ROM stand for Read only Memory,which means that digitally recorded data are registered in pits on surface of the disc is fixed and can not be altered or replaced.The CD is loaded into the CD-ROM player,where the data on the spinning disc is read by a laser .CD-ROM's are different from the vinyl records in that they are not read along a spiral groove.From outer circumference to inner edge;instead each image or piece of information has a co-ordinate on the disc,which is located by the laser.Information picked by the lacer is relayed to the computer,where it is translated into the text and images that appear on the screen .The information is relayed through a SCSI(small computer system interface) .,which processes the electr
COMBAT SPORTS ARE BASED ON THE SKILLS used in fighting .In these sports ,the competitors may be unarmed-as in judo and boxing or armed as in fencing and ken do. Judo is a system of unarmed combat developed in the East.Translated from the Japanese the name means "the gentle way"student learn how to turn an opponent's force to their own advantage..The usual costume is loose white trousers and a jacket fastened with a cloth belt.The colour of the belt indicate the student's level of expertise.,from white belted novices to the expert "black belts".Competitions takes place on a mat or "shiaijo",9 or 10 m(30 or 33 ft)square in size ,bounded by "danger" and " safety" areas to prevent injury. Competitors try to throw ,pin or master their opponent by applying pressure to the arm joi