Ultrasound Scanning

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The ultrasound source produce vibrations at periodic intervals, causing the surrounding tissue particles to be disturbed, and also vibrates in a direction parallel to the direction of the sound waves.

As the tissue particles nearest to the ultrasound source vibrates due to the disturbance from the sound source, they will collide against neighbouring particles, transferring the vibrations from one particle to the next, producing alternate regions of compressions and rarefactions, transmitting the sound waves through the tissues, until the waves eventually reach the fetus, and reflect off the fetus body back to the receiver.

Describe four differences between addition polymerisation and condensation polymerisation.

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1. The monomers used in addition polymerisation contain at least one carbon-carbon double bonds in each molecule while the monomers used in condensation polymerisation contain functional groups at both ends of its molecular structure.

2. Addition polymerisation produces only a single product, the addition polymer while condensation polymerisation produces two products, the condensation polymer and a small molecule, usually water.

3. The empirical formula of the addition polymer is the same as the empirical formula of the monomer while the empirical formula of the condensation polymer is different from the empirical formula of the monomer(s).

4. In addition polymerisation, there is no loss of atoms from the monomers during the polymerisation process. In condensation polymerisation, there is loss of atoms from the monomers during the polymerisation process.