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Raman Spectroscopy: Principle, Instrumentation and Applications

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What is Raman Spectroscopy? Raman spectroscopy was given by an Indian Physicist Sir C.V Raman , which is based on inelastic scattering of monochromatic light with the sample. The resulting light will have a different frequency than incident light due to this inelastic scattering.  This technique is widely used to analyze vibrational, rotational, and other low-frequency interactions in the molecule. This significantly helps in the elucidation of molecular structure, identifying functional groups, etc. Principle of Raman Spectroscopy Raman spectroscopy is based on the inelastic scattering of electromagnetic radiation with the molecule. We have two types of scattering that are elastic and inelastic scattering.  Elastic scattering obeys the Rayleigh law that states that there will be no loss of energy and momentum of the incidence radiation and scattered radiation. That's why this scattering is also known as Rayleigh scattering. Whereas, there will be some conditions (1 in million

Carbohydrates: Definition, Functions and Classification

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What are Carbohydrates ?  Carbohydrates are defined as optically active polyhydroxy aldehydes or polyhydroxy ketones or substances which give these on hydrolysis.  It is to be noted that aldehydic and ketonic groups in carbohydrates are not present as such but generally exist in combination with one of the hydroxyl groups of the molecule in the form of hemiacetals and hemiketals respectively. Carbohydrates include compounds like sugars, starches, glycogen, cellulose, dextrins, and gums. Though they are widely disturbed both in animal and plant kingdoms yet they are obtained mainly from plants by a process known as photosynthesis. Role of Carbohydrates in Biological System One of the primary functions of carbohydrates is to provide energy to the body. Carbohydrates are broken down into glucose which enters the bloodstream then it is taken up into the body's cell and used to produce ATP. These ATP's are used by cells to perform different metabolic tasks. Carbohydrates can b

Crystalline Melting Point: Definition, Factors Affecting and Determination

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What is Crystalline Melting Point ? When a polymer is treated beyond its glass transition temperature (T𝘨), it passes from a glassy state to a rubbery state and further heating causes melting of the polymer and starts flowing.  So we can say that the temperature below which the polymer is in a rubbery state and above which it is a liquid is called the crystalline melting point (T𝘮) of the polymer. Factors affecting crystalline melting point (T𝘮) Following are the factors which affect the crystalline melting point (T𝘮). 1. Chain Flexibility Chain flexibility and crystalline melting point (T𝘮) are inversely proportional to each other that is higher the flexibility, the lower will be the Tm . Also, the presence of double bond and aromatic group in the polymeric backbone lowers the flexibility which increases the crystalline melting point (T𝘮). 2. Size and type of side groups Size and type of size groups greatly influence the crystalline melting point (T𝘮). Bulky or large side g

Atomic Absorption Spectroscopy: Instrumentation, Working and Applications

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What is Atomic Absorption Spectroscopy? Atomic absorption spectroscopy provides us the data about the absorbance of electromagnetic radiation by specific elements. This technique is widely used to determine the presence of unknown elements like alkali and alkali earth metals in the sample.  This is supported by the fact that different metals will absorb different wavelengths of radiation and transmitted radiation is detected by using Lambert Beer's law the graph between the absorbance and the wavelength of the radiation is plotted. Instrumentation of Atomic Absorption Spectroscopy 1. Radiation source The most common radiation source in Atomic Absorption Spectroscopy is a hollow cathode lamp (HCL). It contains a tungsten anode and a cylindrical hollow cathode made of the element of desire which is the element that is to be determined in the sample.  These anode and cathode are sealed into a glass tube filled with an inert gas like neon or argon . When a voltage is applied betwee

Flame Emission Spectroscopy: Instrumentation, Working and Applications

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What is flame emission spectroscopy? Flame emission spectroscopy provides us atomic emission spectrum based on the excitation of atoms from a lower energy state to a higher state. When these atoms return to their original state, they emit radiations which are used to draw the graph.  This technique is widely used to determine the presence of unknown elements like alkali and alkali earth metals in the sample. This is supported by the fact that different metals have different band gaps and they will show different emission spectrums. Instrumentation of flame emission spectroscopy 1. Sample The sample is kept in a sample chamber which is connected to a tube with a nebulizer. The sample may be liquid or solid. The solid sample is first dissolved in a solvent and then analyzed. The sample cannot be a gas. 2. Nebulizer The nebulizer is a closed chamber connected with the sample through a tube. It also has a continuous supply of fuel and oxidants for the smooth flow of the flame. The nebuliz

Factors Affecting Poisoning - Toxicology

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Following are the Factors affecting the poisoning: (A) Factors pertaining to the substance 1. Dose The more the quantity of poison, the more severe will be the toxic effects. But it is not necessary all the time, sometimes larger doses result in vomiting, thus reducing its intensity. But in the majority of cases, more dose will produce more toxicity. 2. State Gases and vapor act more rapidly than liquid poisons. Whereas, liquid poisons act more rapidly than solid poisons. And in solid poisons, fine powdered solid poisons act more rapidly than coarse ones. Thus, the state/form of poison directly affects the effect of poison. 3. Chemical combination The action of poison depends upon the chemical combination that will alter the solubility of the poison in the body. For eg, AgNO₃ and HCl are both strong poisons, but when combined, form or, an insoluble salt of AgCl which is harmless. 4. Mechanical Combination The action of poison is considerably altered when combined mechanically with in

Mode of Action of Poisons

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Any substance (solid, liquid, or gas) that if introduced to a living body, produce ill health or death is called poison.  So, the following are the mode of action of poisons: 1. Local Action In local action, the poison when come in contact with a particular body part then produce harmful effects at the site of contact. For eg, strong acids and alkalis cause irritation and inflammation at the site of contact. 2. Remote Action In remote action, the poison develops toxicity at a particular designated site of action/target irrespective of the route of administration. For eg, Mercury vapors if inhaled produce neurotoxicity. 3. Remote-Local action (Systemic Action) In systemic action, the poison produces toxic effects at the site of administration as well as at the particular target organ to develop their toxic effects. For eg, a Snakebite affects the bitten tissue as well as the central nervous system. 4. General Action In general action, the absorbed poison evokes a response from a wide va

Routes of Administration of Poisons

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Following are the various routes of administration of poisons: (A) Enteral Routes 1. Oral  It is the most commonly used method in which the poison is taken from the mouth. Poison taken from this route directly affects GIT, the upper respiratory tract, stomach, and other organs. 2. Sublingual In this method of administration, the poison is placed beneath the tongue and spread over the buccal mucosa (the lining of cheeks and the back of lips). It shows rapid absorption and directly passes into the systemic circulation. 3. Rectal In this method of administration, the poisons are inserted into the anus where they are absorbed into the bloodstream directly through the mucous membranes. (B) Parenteral Routes  Routes other than enteral are called parenteral. 1. Intravenous In this method of administration, the poison is injected into the body through veins , providing a direct route for the poison to get into the blood and thus circulate throughout the body very quickly and showing the sy

IR Spectroscopy: Definition, Instrumentation, Working and Applications

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What is IR Spectroscopy? Infrared spectroscopy is absorption spectroscopy that deals with the recording of the absorption of the electromagnetic radiations of the infrared region of the electromagnetic spectrum. The IR region ranges from 700-1000 nm.   This technique is widely used for the detecting of functional groups, characterization of proteins, analysis of various liquids, and identification of molecules and their composition. Instrumentation of IR spectroscopy 1. Radiation source The radiation source should emit IR electromagnetic radiations which are steady, intense, and extended over the desired wavelength. That's why radiation sources like Nernst glower, globar source, incandescent lamp, and mercury arc lamp. 2. Monochromator It helps to select desired frequencies of IR radiations because our sample will only absorb some specific frequencies of IR radiations. Prism and grating are the most commonly used monochromators. 3. Sample cells and sampling IR spectroscopy is used

U.V-Visible spectroscopy: Instrumentation, Working and Applications

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What is U.V-Visible spectroscopy? U.V-Visible spectroscopy is absorption spectroscopy that deals with the recording of the absorption of electromagnetic radiation of the U.V and Visible regions of the electromagnetic spectrum. The U.V-region ranges from 200-400 nm whereas the visible region ranges from 400 to 800 nm.   So, we can say that U.V-Visible spectroscopy utilizes a 200-800 nm range for working. This technique is widely used for detecting the presence and elucidating the nature of the conjugated multiple bonds and aromatic rings. Instrumentation of U.V-Visible spectroscopy 1. Radiation source Hydrogen-discharge lamp is the most commonly used source of radiation in the U.V region (200-400 nm) whereas a deuterium-discharge lamp is used when more intensity (3-5 times) is desired. A tungsten-filament lamp is used when absorption in the Visible region (400-800 nm) is to be determined. 2. Monochromator It helps to separate the radiations into separate wavelengths that are it onl

Forensic Anthropology: Definition, History and Application

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What is Forensic Anthropology? Forensic anthropology is a specialized branch of physical anthropology that deals with the medico-legal purpose to establish the identity of the deceased person. It uses the knowledge of human anatomy like the size of bones, hairs, length, features of bones, teeth, etc to determine the person's age, sex, stature, and race. In some cases, it can also predict the cause of death of the person by studying the different features on the bone. Forensic anthropologists are often called to the scene of the crime to study the remains of human remains which got decomposed, burned, mutilated, or difficult to recognize. Forensic anthropology can be used in accident cases like aircraft crashes, arson, fire accidents, genocide, etc. History of Forensic Anthropology The history of forensic anthropology dates back to the 19th century when anatomists were often asked for human identification through their skeletal. In 1835, Mathieu Orfila , a french forensic medicine

Process of Dyeing Fabric

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To dye fiber with a dye, some certain steps are to be followed only then dye molecules will get fixed on the fiber and we will get our desired colored fiber. So, the following are some steps that are to be followed during the dyeing process: 1. Sourcing and Bleaching In this type, fiber is collected from the source and any loose, hairy or gummy materials are removed from the fiber. Then, impurities or any natural color of the fiber are removed through bleaching. 2. Preparation of Dye bath In this step, a dye bath is prepared in which the whole process of dyeing a textile fiber takes place. A dye bath contains dye and water which is generally heated to get a proper mixture. 3. Coloration In this step, textile fiber is colored through dyeing. The color should not readily be removed by rinsing in water or by normal washing procedures. Also, the color should not fade by exposure to light. Following are the phenomenon involved at the molecular level during the coloration of textile mater

History and Development of Forensic Science

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The term 'forensic' is obtained from the Latin word 'Forensis' which means "court of justice" . So we can say, forensic science is a branch of science that deals with the individualization, recognition, identification, and evaluation of physical evidence by the use of natural science for criminal justice. Forensic science is also known as 'criminalistics' in some countries with branches like fingerprints, documents, ballistics, odontology, etc. It is derived from major branches of science like physics, biology, and chemistry. In the 19th century when natural science began to develop rapidly, forensic science started deepening its roots in criminal justice. Forensic science was widely accepted because there is no place for the torture of criminals for detecting crime in a civilized society.  Forensic science was made more famous by sir Arthur Conan Doyle's fictional character 'sherlock homes' in which crime investigation is done by scie

Documentation of the Crime Scene: Step by Step

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What is documentation of the crime scene and Why it is done? After securing the crime scene, the next most important step is documentation of the crime scene because documentation permanently records the crime scene and its physical evidence. Documentation should be done without any wastage of time as the scene and its evidence may get altered over time. The documentation should be done innovatively and the originality of the crime scene should be maintained and documentation should not have pauses or breaks, it should remain constant till the whole crime scene is documented. There are four main tasks of documentation that is note-making, photography, videography , and sketching . It should be noted that all four tasks are necessary and none is a substitute for another. For example, notes are not substitutes for photography, video is not a substitute for sketching, etc. Following are the sequence for crime scene documentation: 1. Note making Documentation of crime scene in the f

Phenolphthalein: Preparation, Properties and Applications

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What is Phenolphthalein? Phenolphthalein is an organic compound having the chemical formula C₂₀H₁₄O₄ that is used as a ㏗ indicator in acid-base titrations. So, as an indicator, it turns pink to red in alkaline and is colorless in acid solutions. In short, it can be written as 'HIn' or '㏗㏗'. Preparation of Phenolphthalein Phenolphthalein can be synthesized by condensation of phthalic anhydride with two equivalents of phenol under acidic conditions. Properties of Phenolphthalein Phenolphthalein is white-yellow, in its crystalline form. It is readily soluble in alcohols and mildly soluble in water. It does not have taste or smell and it is carcinogenic. It appears colorless till pH 8.5 and above that it appears as pink to deep red. Applications of Phenolphthalein It is commonly used as an indicator in acid-base titrations. It turns colorless in acidic solutions and pink in basic solutions. It may be used as a laxative but it is not advisable due to the suspected car