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Crime Scene: Definition, Types and Characteristics

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What is a Crime Scene ? A place where the crime is committed or where the maximum physical evidence related to crime is found is known as a crime scene. A crime scene is a starting point of the investigation which provides information about the suspect and the victim. This helps to reconstruct the crime and fast resolution of the case. It is noted that the crime scene is not limited to a single place but may extend to a wider area depending upon the nature of the crime committed. For example, In a murder case where murder is done at one place and the body is disposed on another place. In this case, we have two crime scenes that give information about the crime. Types of Crime Scene Based on evidence found on the crime scene: 1. Primary Crime Scene The crime scene where the actual crime occurred or where more usable pieces of evidence were found is known as the primary crime scene. For example, A murder scene, theft, assault, etc. 2. Secondary Crime Scene The crime scene which is some...
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Conducting Polymers: Definition, Examples, Properties and Applications

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What are Conducting Polymers? As the name suggests organic polymers that conduct electricity are known as conducting polymers. They are also known as intrinsically conducting polymers (ICPs) and they have alternating single and double bonds along the polymer backbone (conjugated bonds) or that are composed of aromatic rings such as Phenylene, naphthalene, anthracene, pyrrole, and thiophene which are connected through carbon-carbon single bonds. Examples: Polyacetylene, Polypyrrole, Polyaniline, etc What is the reason behind conducting nature of these polymers? Conducting polymers comes in two forms that are doped conducting polymers and non-doped conducting polymers. The conductivity of non-doped conjugated polymers is due to the existence of a conductivity band similar to a metal. In a conjugated polymer, three of the four valence electrons form strong sigma bonds through sp² hybridization where electrons are strongly localized. The remaining unpaired electron of each carbon atom re...
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Alizarin Dye: Definition, Synthesis, Properties and Application

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What is Alizarin Dye? Alizarin is a red dye having chemical formula C₁₄H₈O₄ which is generally used to dye cotton, wool, and silk.  Alizarin was originally obtained from the root of a common madder plant called Rubia tinctorum. It is also known as Turkey Red as it was best dyed in Turkey and in 1869, it becomes the first natural dye to be duplicated synthetically. Synthesis of Alizarin Following are some methods for the synthesis of alizarin: 1. From anthraquinone The starting material for the synthesis of alizarin is an anthraquinone. It can be easily obtained by Friedel-crafts acylation of benzene with phthalic anhydride. Anthraquinone is then sulfonated with concentrated sulphuric acid at a high temperature to give anthraquinone-b-sulphonic acid. Alizarin is obtained by fusion of anthraquinone-b-sulphonic acid with caustic soda. 2. By bromination of anthraquinone Another synthesis is given by Graeve (in 1869). In this method, anthraquinone is brominated to yield dibromo anthr...
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