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Wednesday, March 31, 2010

general science#6

PHYSICS: PARTICLE PHYSICS

Overview

  • The atom was discovered by John Dalton in 1802
  • However, even more fundamental particles were discovered in the 20th century
  • Particle physics focuses on subatomic particles including electrons, protons and neutrons
  • Many fundamental particles do not occur in nature but can be created in high energy collisions of other particles
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Standard Model of particle physics

  • The Standard Model describes the current classification of elementary particles
  • It describes strong, weak and electromagnetic forces using gauge bosons
  • The Standard Model does not include gravitation, dark matter and dark energy
  • The Standard Model was developed by Sheldon Glashow, Steven Weinberg and Abdus Salam in the 1960s. They won Nobel in Physics in 1979
  • The Model contains 24 fundamental particles
  • It predicts the existence of the Higgs Boson, which is yet to discovered
  • All particles of the Standard Model have been observed in experiments, except the Higgs Boson
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Elementary particles

  • All elementary particles are either fermions or bosons
  • Fermions are particles associated with matter, while bosons are particles associated with force
  • Fermions can be divided into Quarks and Leptons
  • Bosons can be divided into Gauge Bosons and Other Bosons (including Higgs Boson)
  • Protons and neutrons are examples of Hadrons, which are composites of Quarks
  • Electrons are elementary particles by themselves
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Important particle physics labs

Facility Location Established Famous for
Brookhaven National Lab New York 1947 World’s first heavy ion collider
World’s only polarized proton collider
Budker Institute of Nuclear Physics Novosibirsk (Russia) 1959 World’s first particle accelerator
European Organization for Nuclear Research Geneva 1954 World’s largest particle physics lab
Birthplace of World Wide Web

Large Hadron Collider (LHC)
German Electron Synchrotron (DESY) Hamburg 1959
Fermilab Chicago 1967 Tevatron – world’s second largest particle accelerator
High Energy Accelerator Research Organization (KEK) Tsukuba (Japan)

SLAC National Accelerator Lab Stanford University 1962 Longest linear accelerator in the world
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CHEMISTY: CERAMICS

Overview

  • A ceramic is an inorganic, non-metallic solid prepared by the action of heating and subsequent cooling
  • The earliest ceramic materials were pottery made from clay
  • Ceramics are resistant to chemical erosion and high temperatures (up to 1600C)
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PROPERTIES OF CERAMICS

  • Mechanical properties
    • Ceramic materials are usually formed by ionic or covalent bonds
    • These materials tend to not be elastic and fracture easily
    • Ceramics are also porous
    • In general ceramics have poor toughness and have low tensile strength
  • Electrical properties
    • Some ceramics are semiconductors
    • Semiconducting ceramics are made using zinc oxide
    • Under extremely low temperatures, some ceramics exhibit superconductivity
    • Most ceramics exhibit piezoelectricity i.e. the conversion of mechanical stress to electrical signals. This effect is commonly used in quartz watches
  • Optical properties
    • Ceramics (esp. those based on aluminium oxide) can be made translucent
    • This has immediate applications in sodium-vapour lamps and dental restorations
    • Ceramics can be made transparent with applications in laser technology
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TYPES OF CERAMICS

  1. Structural ceramics such as bricks, pipes, floor, roof tiles etc
  2. Refractory ceramics such as kiln lining, steel and glass making crucibles
  3. Whitewares such as tableware, wall tiles, pottery, sanitary products
  4. Technical ceramics such as jet engine turbine blades, ballistic protection etc
MANUFACTURE OF CERAMICS

  1. Milling
    1. Process by which materials are reduced in size
    2. Involves breaking of cemented material or pulverization
    3. Techniques used include ball mill, roll crusher, jaw crusher, wet attrition mills
  2. Batching
    1. Is the process of weighing the oxides according to recipes and preparing them for further processing
  3. Mixing
    1. Involves mixing the various components in the appropriate proportions
    2. Uses ribbon mixers, Mueller mixers and pug mills
  4. Forming
    1. This is the process of the making the mixed materials into desired shapes such as toilet bowls, spark plugs etc
    2. Forming techniques include extrusion, pressing and slip casting
  5. Drying
    1. Controlled heat is applied to dry the materials and obtain rigid shape
  6. Firing
    1. Dried parts are processed through a controlled heating process and oxides are chemically changed to cause sintering and bonding
Keywords: India, ias, upsc, civil service, study material, general studies, science, free

BIO-CERAMICS

  • Bacteria, plants and animals exhibit a tendency to form crystalline materials composed of silicon
  • These bioceramics show exceptional physical properties such as strength, fracture resistance etc
  • Bio-ceramics are usually made of proteins such as keratin, elastin, chitin and collagen
  • The mother-of-pearl portion of marine shells exhibit the strongest mechanical strength and fracture toughness of any non-metallic substance known
Keywords: India, ias, upsc, civil service, study material, general studies, science, free

APPLICATIONS OF CERAMICS

Application Ceramic components Notes
Armoured vests Alumina, boron carbide Protects against high-calibre rifle fire
Dental implants, synthetic bone Artificial hydroxyapatite (natural mineral of bone)
Ball bearings Silicon nitride Harder, more resistant to heat than metal bearings
Earthenware Kaolin, boll, flint Opaque
Used to make cups, saucers etc
Chinaware Leached granite (to remove quartz and mica) Translucent
Resists scratching
Porcelain Kaolin, feldspar, quartz White, semi-opaque
Highly resistant to scratching

Stronger than glass
Stoneware Kaolin, feldspar, quartz Similar to porcelain but from poor grade raw materials
Hard, infusible
Space shuttles Extremely pure Silica Used on the outer surface of shuttles to withstand heating during atmospheric re-entry
Space shuttle Colombia burnt up on re-entry due to damage to ceramic tiles
Keywords: India, ias, upsc, civil service, study material, general studies, science, free

BIOLOGY: GENETIC ENGINEERING

Overview

  • Genetic engineering refers to the direct manipulation of an organism’s genes
  • Genetic engineering is also referred to as recombinant DNA technology, genetic modification and gene splicing
  • Genetic engineering uses cloning and transformation of molecules to alter the structure and characteristics of genes
  • Examples of genetic engineering include improved crop technologies, synthetic hormones, and creation of experimental mice
Keywords: India, ias, upsc, civil service, study material, general studies, science, free

Process of genetic engineering

The process of genetic engineering has five main steps:
  1. Isolation of the genes of interest
  2. Insertion of the genes into a transfer vector
  3. Transfer of the vector to the organism to be modified
  4. Transformation of the cells of the organism
  5. Selection of the genetically modified organisms from those that have not been successfully modified
Keywords: India, ias, upsc, civil service, study material, general studies, science, free

Applications of genetic engineering

  • The first genetically engineered medicine was synthetic insulin
  • Genetic engineering has been used to produce vaccines for hepatitis B
  • Creation of genetically modified foods such as soybean, corn, canola and cotton seed oil. GM foods have higher resistance to pests, bacterial/fungal infections, higher yield and higher nutritional value
  • Gene therapy using viruses to treat severe combined immunodeficiency (SCID)
  • Using genetically modified virus to construct environment friendly lithium-ion battery
  • Using human eggs from a second mother to allow infertile women with genetic defects in their mitochondria to have children
  • Artificial DNA, called Synthetic Organism (SO-1), with unknown functions has been created
Keywords: India, ias, upsc, civil service, study material, general studies, science, free

Milestones in genetic engineering

  • 1953: James Watson (USA) and Francis Crick (Britain) discover structure of DNA. They win Nobel in Physiology or Medicine in 1979
  • 1973: Stanley Cohen (USA) and Herbert Boyer (USA) develop a technique to clone segments of DNA molecules
  • 1976: Genentech, the first company dedicated to producing genetically engineered products is established in San Francisco. It was founded by Herbert Boyer and Robert Swanson
  • 1979: Genetic engineering used to synthesize insulin
  • 1981: scientists at Ohio university transfer genes from other organisms into mice
  • 1990: Human Genome Project launched
  • 1990: first gene therapy experiment performed on a four-year old girl with adenosine deaminase deficiency. Developed by French Anderson
  • 1996: a yeast known as Saccharomyces cerevisiae is the first eukaryotic genome to be sequenced by more than 100 labs collaboratively around the world
  • 2003: Human Genome Project announces complete mapping of human genome
Keywords: India, ias, upsc, civil service, study material, general studies, science, free

GENETICALLY MODIFIED FOODS

  1. BT-Cotton
    1. BT-Cotton is a genetically modified variety of cotton into which Cryiae gene from the bacillus thuriegenois bacteria have been introduced
    2. This gene produces a toxin called BT-Toxin in every part of the plant thereby destroying the dreaded cotton pest Bollworm
    3. This technology was developed by US seed company Monsanto
    4. However, concerns include evolution of super-pests with higher levels of resistance, destruction of agriculturally beneficial organisms like bees, soil microflora etc
  2. Terminator gene
    1. Terminator gene is a seed variety developed using genetic engineering
    2. It causes the seed to self-destruct after it has been used to raise the first generation of crops
    3. This is done in order to prevent farmers from raising subsequent generations of crops without paying royalties
    4. Concerns include this self-destruct gene may be transferred to other plants by cross-pollination leading to extinction of traditional agricultural production
    5. It is also known as Genetic Use Restriction Technology (GURT) and was developed by the US Department of Agriculture in conjunction with the Delta and Pine Land Co.
  3. Golden rice
    1. Type of rice crop provided with a gene to develop Beta-Carotene
    2. This helps production of vitamin A in the body
    3. This helps fight vitamin A deficiency, the primary cause of childhood blindness
    4. Beta-carotene gives rice a yellow colour and hence is called Golden Rice
    5. Created by Swiss Federal Institute of Technology
  4. GM Cabbage
    1. Cabbage that will resistant to attack of Diamond Back Moth
    2. Developed by Indian Agricultural Research Institute (New Delhi)

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