Antiseptics

Antiseptic, agent that kills or inhibits the growth of microorganisms on the external surfaces of the body. Antiseptics should generally be distinguished from drugs such as antibiotics that destroy microorganisms internally, and from disinfectants, which destroy microorganisms found on nonliving objects. Germicides include only those antiseptics that kill microorganisms. Some common antiseptics are alcohol, iodine, hydrogen peroxide, and boric acid. There is great variation in the ability of antiseptics to destroy microorganisms and in their effect on living tissue. For example, mercuric chloride is a powerful antiseptic, but it irritates delicate tissue. In contrast, silver nitrate kills fewer germs but can be used on the delicate tissues of the eyes and throat. There is also a great difference in the time required for different antiseptics to work. Iodine, one of the fastest-working antiseptics, kills bacteria within 30 sec. Other antiseptics have slower, more residual action. Since so much variability exists, systems have been devised for measuring the action of an antiseptic against certain standards. The bacteriostatic action of an antiseptic compared to that of phenol (under the same conditions and against the same microorganism) is known as its phenol coefficient. Joseph Lister was the first to employ the antiseptic phenol, or carbolic acid, in surgery, following the discovery by Louis Pasteur that microorganisms are the cause of infections. Modern surgical techniques for avoiding infection are founded on asepsis, the absence of pathogenic organisms. Sterilization is the chief means of achieving asepsis.

Binoculars..How they work

Binoculars are essentially a pair of identical refracting telescopes; they have a large objective lens at the front and a number of smaller lenses to enable an image to be brought into sharp focus.
Prisms are used so that larger objective lenses can be used - otherwise they would be limited by the distance between the eyes. The prisms reflect the image through two right angles in the binoculars. The prisms also reverse the inversion that occurs in refracting telescopes.

Joseph E. Murray

E. Donnall Thomas

The Nobel Prize in Physiology or Medicine 1990 was awarded jointly to Joseph E. Murray and E. Donnall Thomas "for their discoveries concerning organ and cell transplantation in the treatment of human disease"

Bar Code

BAR CODE
Bar codes (also called Universal Product Codes or UPC's) are small, coded labels that contain information about the item they are attached to; the information is contained in a numerical code, usually containing 12 digits. UPC's are easily scanned by laser beams. UPC's are used on many things, including most items for sale in stores, library books, inventory items, many packages and pieces of luggage being shipped, railroad cars, etc. The UPC may contain coded information about the item, its manufacturer, place of origin, destination, the owner, or other data. The first "bullseye code" was invented by Norman Joseph Woodland and Bernard Silver, from work which they began in 1948. On October 20, 1949, they patented their bullseye code (a series of concentric circles that were scannable from all directions, using regular light). Woodland and Silver patented a new UPC in October 1952; the UPC was also improved and adapted by David J. Collins in the late 1950's (to track railroad cars). UPC's were first used in grocery stores in the early 1970's.