ND2 Notes

Electronic Structure of Elements

Electrons revolve only in permitted orbits identified using letters K, L, M, N, P etc., starting from the nucleus outwards. The shells are known by their principal quantum number n (n=1 for K shell, n=2 for L shell, n=3 for M shell). Maximum electrons per shell = 2n².

Covalent Bond

Covalent bonds are formed by sharing of electrons. Each valence electron of an atom forms a direct bond with the valence electron of an adjacent atom. This can occur between two similar or dissimilar atoms.

Energy Bands

Valence Band: The range of energies possessed by valence electrons. May be completely or partially filled but cannot be empty.

Conduction Band: The range of energies possessed by conduction electrons. All electrons in the conduction band are free electrons. Insulators have an empty conduction band.

Forbidden Energy Gap: The separation between conduction band and valence band on the energy level diagram. The greater the energy gap, the more tightly valence electrons are bound to the nucleus.

Conductors, Semiconductors and Insulators

Conductors: Allow easy passage of electric current. The valence and conduction bands overlap each other.

Semiconductors: Electrical conductivity lies between conductors and insulators. Valence band is almost filled and conduction band is almost empty. Energy gap is very small (~1eV).

Insulators: Do not allow electric current. Valence band is full, conduction band is empty. Energy gap is very large (~15eV).

Intrinsic & Extrinsic Semiconductors

Intrinsic Semiconductor: A semiconductor in an extremely pure form. Silicon and Germanium are the two most common types, both having four valence electrons.

Extrinsic Semiconductor: A semiconductor that has been doped with impurities to increase and control conductivity. Two types: n-type (pentavalent impurity added, more free electrons) and p-type (trivalent impurity added, more holes).

Doping: The process of adding impurities to an intrinsic semiconductor to increase and control conductivity.

P-N Junction Diode

When a P-N junction is formed, free electrons from the n-type diffuse into the p-type to fill holes. The region on either side of the junction becomes free of majority charge carriers — this is called the Depletion/Barrier Layer.

Forward Bias: Positive terminal connected to p-type, negative to n-type. Cancels the potential barrier, allowing current flow.

Reverse Bias: Negative terminal connected to p-type, positive to n-type. Increases the potential barrier, preventing current flow.

Types of Diodes & Applications

Zener Diode: Used as voltage regulators, fixed reference voltage, calibrating voltmeters, peak clippers.

Tunnel Diode: Used in logic memory storage, as amplifier, microwave oscillator (~10GHz), relaxation oscillator, ultrahigh-speed switch.

LED (Light Emitting Diode): Used as indicator lamps, seven-segment displays, numeric displays in calculators.

Photodiode: Used as fast counters, in switching circuits, encoders, optical communication equipment, demodulation.

Varactor Diode: Used as automatic frequency control device, FM modulator, adjustable band pass filter.

Rectification

Half-Wave Rectification: When the sine wave goes positive, the diode is forward biased and conducts current through the load resistor. Only positive half-cycles appear at the output.

Full-Wave Rectification: Uses centre-tap configuration with two diodes. Both halves of the AC cycle appear at the output.

Breakdown Mechanisms

Avalanche Breakdown: Carriers accelerate and gain enough energy in the electric field to knock loose valence electrons, causing an avalanche of carriers and a massive increase in reverse current.

Zener Breakdown: In heavily doped regions, the depletion layer becomes very narrow and the intense electric field breaks covalent bonds directly, generating hole-electron pairs and causing reverse current to rise abruptly.

Thermionic Valves

Triode: Three electrodes — cathode, anode, and control grid. The anode current is controlled by varying the p.d between the grid and cathode. A small change in grid voltage produces a large change in anode current.

Tetrode: Four electrodes — cathode, anode, control grid, and screen grid. The screen grid provides electrostatic shielding between anode and control grid, minimizing feedback effects. Anode current remains nearly constant over large variation of anode voltage.

Pentode: Five electrodes — adds a suppressor grid between anode and screen grid. Prevents secondary electrons from reaching the screen grid, eliminates feedback action, and increases amplification factor.

Lecturer: Mr. Moses N. James

CONTROL OF MICRORGANISMS

Microorganisms are abundant in the environment, living in soil, in water, on the surfaces of plants and animals and inside many types of multicellular organisms, including humans. Fortunately, most microorganisms live freely in the environment without causing harm to humans or other organisms; in fact most of them are beneficial in a variety of ways. For these reasons, humans seek to control only certain types of microorganisms and under relatively few specific circumstances. We exert control over microorganisms associated with food materials, so that foods can be stored and made available for human consumption without being consumed by microorganisms first. We seek to control microorganisms that might cause damage to agricultural crops, forest trees and ornamental plants maintained for our purposes, and we seek to control potential pathogens that threaten our health or the health of animals we consider important for various reasons. Microbial control methods vary considerably depending on where and on what types of microorganisms they are being applied.

Microbial control means to inhibit or prevent growth of microorganisms. This control is affected in two basic ways: 1.by killing microorganisms or 2.by inhibiting growth of microorganisms. Control of microbial growth involves use of chemical and physical agents which either kill or prevent growth of microorganisms.

The effective control of microorganisms is required.

1. To prevent transmission of disease and infection,

2. To prevent spoilage of food,

3. To prevent interference of contaminating microorganisms in industrial processes and

4. To prevent contamination of materials used in pure culture work in laboratories.

Many terms are associated with the control of microorganisms.

6.1 Definition of terms

a) Sterilization: It is a process of destroying all forms of life by physical and chemical agents. Objects that are sterile are free from all living cells, spores and viruses.

b) Disinfection: Disinfectant kills vegetative cells of organisms capable of causing infection but not spores. Disinfection is done by chemical agents called disinfectants. Disinfectant is normal applied to inanimate objects such as floors, utensils and equipments etc.

c) Antiseptic: Any substances which prevent sepsis either by killing microorganisms or inhibiting their growth and activity is designated as antiseptic. The antiseptic can be applied to body tissues without causing injury to tissue.

d) Sanitizer: It is an agent that reduces the microbial population to safe level. Sanitizers are applied to inanimate objects such as equipments and utensils used in dairy and food industry.

e) Germicide: It is an agent that kills vegetative cells but not spores.

f) Bacteriocide: is identical term that kills bacterial cells but not spores. Likewise terms fungicide, viricide are used that kills fungi and viruses respectively.

g) Microbiostatic: It is a condition in which growth of microorganisms is prevented by using micro biostatic agent.

h) Bacteriostatic and fungistatic agents are those agents which stops the growth of bacteria or fungi respectively.

i) Antimicrobial agent: It is an agent that interferes with growth and activity of microbes. When its action is directed against bacteria, agent is designated as antibacterial and when its action is directed against fungi,

h) Preservative: It prevents growth of microorganisms.

6.2 Control methods

The control of microorganisms can be achieved by a variety of chemical and physical methods. Sterilisation is generally achieved by using physical means such as heat, radiation and filtration. Chemical methods, whilst effective at disinfection, are generally not reliable for achieving total sterility.

A variety of microbial control methods involve physical factors such as temperature, pressure and radiation. Variations exist within these categories, and in some cases, more than one factor can be applied simultaneously. Some specific examples are listed below.

Temperature

Moist heat & Dry heat are the two categories of heat which are commonly employed for the control of microorganisms.

Moist Heat

Moist heat sterilization using moist heat is called moist heat sterilization. Moist Heat kills organisms by denaturation or coagulation of cellular proteins. In following methods moist heat is used for sterilization:

1) Boiling: Objects (Glass-wares instruments) are exposed to boiling water (at temperature 1000C) for 10 minutes. Boiling kills vegetative forms of bacteria & many viruses within about 10 minutes. Endospores and some viruses are not destroyed so quickly (Within 10 minutes) e.g. Hepatitis virus can survive up to 30 minutes of boiling and some bacterial spores can survive for more than 20 hours. Boiling is therefore not a reliable sterilization procedure. This method is not recommended for the sterilization of instruments used for surgical procedures and should be regarded only as a mean of disinfection.

2) Fractional sterilization (Tyndallization): In tyndallization, objects, media which decompose at high temperature are exposed to free flowing steam at a temperature of 1000C for 20 minutes for three consecutive days with an incubation period of 24 hours at Room Temperature. John Tyndall has first proposed this method of sterilization. This method is also called Fractional sterilization. Arnold steamer is used for this type of sterilization. Arnold steamer consists of tinned copper cabinet. The lid is conical, enabling drainage of condensed steam and a perforated tray filled above the water level ensures that the material placed on it is surrounded by steam.

First exposure of media to steam, kills all vegetative bacteria and but not spores. After 1st exposure of media to steam, medium is incubated at room temperature for 24 hours. During incubation, spores will germinate which are not killed after 1st exposure. Again after 1st incubation period, medium is exposed to steam to kill vegetative cells derived from germination of spores. After second exposure, again medium is incubated to germinate remaining spores. This process is repeated one more time to sterilize the medium completely. This method fails to sterilize the media if: 1) The medium is unsuitable for the germination of spores. 2) Spores of anaerobic bacteria will not germinate if the material is in contact with air and spores of aerobic bacteria will not germinate, if the material is not freely exposed to air. 3) It is a time consuming method for sterilization.

3) Pasteurization

Pasteurization is developed by Louis Pasteur to prevent the spoilage of beverages, milk, juices, etc. In pasteurization, the product is subjected to controlled heat treatment where specific types of microorganisms are killed but does not kill all organisms. Temperature used for the pasteurization depends upon the product to be pasteurized and method of pasteurization. In the case of pasteurization of milk, it is heated to 71.60C for at least 15 seconds in the high temperature short time method or 62.90C for 30 minutes in the low temperature holding method. In ultra-pasteurization, also known as ultra high temperature (UHT) pasteurization, the milk is brought into contact with steam at 140°C for one or two seconds. Pasteurization reduces the number of microorganisms in a product or food. It kills pathogens that are transmitted in milk, i.e., Staphylococci, Streptococci, Mycobacterium tuberculosis and many spoilage organisms therefore increases the shelf life of milk especially at refrigeration temperatures (below 100C).

4) Autoclaving (Steam under pressure):

In this method of sterilization, moist heat (steam under pressure) having temperature above boiling water is used for sterilization. Saturated steam under pressure has more penetration power and higher temperature than boiling water. Autoclave is most commonly used instrument for autoclaving. Water boils at 1000C when placed in open vessel but in autoclave water does not boil even at 1000C because it is a closed vessel. In autoclave, sterilization by steam under pressure is carried out at temperature between 1080C and 1470C. By increasing steam pressure (or vapour pressure of steam), steam temperature can be increased. In autoclave, steam comes into contact with cooler surface and condenses into water on it, thus causes the release of latent heat from water to that surface of item and increase temperature of item. The condensed water provides moist condition for killing cells. Steam at a pressure of about 15 Psi (1210C) will kill all organisms and their endospores in about 15 minutes, when the organisms either contact the steam directly or are contained in small volume of aqueous medium. Sterilization of medium in large containers also requires extra time.

The Laboratory Autoclave

The laboratory autoclave consists of a vertical or horizontal cylinder of gun or stainless steel metal. The lid is fastened by screw clamps and made air tight by an asbestos washer. The autoclave has on its lid, a discharge tap for air and steam, pressure gauge and safely valve that can be set to blow off at any desired pressure. Heating is done by gas or electricity. For autoclaving of materials, at first sufficient water is put in the cylinder then the material to be sterilized is place on the tray and heating is started. The lid is screwed tight with the discharge tap open. The safety valve is adjusted to required pressure (but in most of the cases it is self-adjusted by manufacturer). The steam and air mixture is allowed to escape freely till all air has been replaced. This can be tested by observing accumulation of water droplets at the outlet of discharge tap and then the discharge tap is closed. The steam pressure rises inside and when it reaches the desired set level, the safely valve opens and the excess steam escapes. From this point, the heating period is calculated. When holding period is over the heater is turned off and autoclave is allowed to cool till the pressure gauge indicates that the inside pressure is at atmospheric pressure. The discharge tap is opened slowly and air is allowed to enter the autoclave. If the tap is opened when pressure inside has fallen below atmospheric pressure, an excessive amount of water will be evaporated and lost from the media. If air is not completely removed, the desired temperature will not be attained at specified pressure. To sterilize glassware’s, bandages, care must be taken to ensure that steam contacts all surfaces. Aluminum foil is impervious to steam and should not be used to wrap materials that are to be sterilized, paper should be used instead. There is no facility for drying the drying the load after sterilization before taking it out. The collection of water upon cooler surfaces during autoclaving causes metal rust. Corrosion inhibitor like sodium benzoate is applied to metallic items before autoclaving to prevent rusting.

Autoclaving is used to sterilize culture media, instruments, dressings, solutions, syringes and other items that can withstand high temp and pressure. It is also used to sterilize bacteriological media and destroy pathogenic cultures. The autoclave is equally valuable for sterilization of glassware and metal ware, and is most basic instrument of every microbiology laboratory. Today’s autoclaves are equipped with the devices to maintain proper pressure and record internal temperature during operations. Irrespective of these developments, it is necessary to keep watch on pressure and maintain it appropriately. Some plastic wares cannot be sterilized as they melt in the high heat, and sharp instruments often become blunt. Many substances breakdown during the sterilization process and oily substances cannot be sterilized in autoclave because they do not mix with water. Commercially available tapes are used as sterility indicators where color of the tape changes due to chemical reaction when the proper times and temperatures have been reached. Normally such sterilization indicators are kept near the center of autoclave surrounding materials to be sterilized to ensure proper penetration of heat. Another widely used method for sterility testing is preparations of specified species of bacterial endospores such as Bacillus stearothermophilus, impregnated into paper strips or present in an ampule of medium enclosed in a soft plastic vial. The vial is placed in the center of the material to be autoclaved. These spores are then aseptically inoculated into culture media after autoclaving and incubated. Sterilization is ensured by absence of growth in the culture media (indicates survival of the endospores).

Dry heat

Dry heat acts mostly by oxidizing or burning the cell constituents. Dry heat dehydrates cells, resulting in lack of water thus reduces the probability of protein coagulation. Penetration power of dry heat is low thus It is less effective as killing agent than moist heat. Different types of dry heat sterilization are

Incineration (Direct Flaming)

Incineration is the method where material to be sterilized is directly burnt in the flame. During the laboratory experiments, inoculating needles, forceps, etc are sterilized by incineration in which inoculating needle and forceps are directly introduced into a flame of burner till they become red hot. However, care should be taken to prevent spattering, because the droplets which fly off are likely to carry viable organisms. This problem can be reduced by inserting needle inside the tube. The method is 100% effective for sterilization. No known living organisms can withstand treatment given in incineration.

2) Hot air sterilization

The apparatus used for this type of sterilization is electric or gas hot air oven. The oven is usually heated by electricity with heating elements in the wall of chamber and it must be fitted with fan to ensure even distribution of air. It should not be overloaded. The material should be arranged in the manner which allows free circulation of air in between. Glass wares should be dry before being placed in oven. Test tubes, flasks etc should be plugged with cotton wool other glass wares such as petri- dishes and pipettes should be wrapped in Kraft paper. The oven must be allowed to cool slowly for about two hours before the door is opened since, the glass wares may get cracked by sudden or uneven cooling. Oven is operated at 1600C for one hour. In oven to sterilize items, longer period and higher temperature than autoclave because in autoclave heat in water is transferred to cool body and in oven the heat in air is transferred to cooler body. Heat in water is transferred to cool body more readily. It is used to sterilize glass wares, forceps, scissors, swabs, fats, greases etc.

Oven is used for sterilization of instruments used in ophthalmic surgery but a sterilization time of 2 hrs at 1500C is recommended. Rubber materials will not stand the temperature normally used for sterilization in oven.

Freezing (exposure to low temperatures) – Freezing is a bacteristatic physical control method applied frequently in a wide variety of settings. Freezing is used extensively to control microorganisms associated with food materials, drugs, research chemicals, etc. Freezing effectively inhibits the growth of most microorganisms by stopping metabolic processes, but is rarely cidal to bacteria because most of them are psychroduric. Bacteria culture collections are typically maintained in ultra low freezers (at temperatures of minus 72 to minus 80o C) and remain fully viable. It is important to remember when thawing large frozen food items (e.g., turkeys) that the external surfaces can reach temperatures suitable for microbial growth long before the center is thawed. Microorganisms and nutrients are typically abundant on skin surfaces and growth will occur if moderate temperatures are maintained for any length of time. Cold temperatures commonly maintained within refrigeration units slow metabolic processes and effectively prevent the growth of some types of microorganisms, but not all. Potential pathogens including Campylobacter and Listeria can grow on food materials maintained at temperatures commmon within most refrigerators

Sterilisation by irradiation

Certain types of irradiation are used to control the growth of microorganisms. These include both ionising and non-ionising radiation. The most widely used form of non-ionising radiation is ultraviolet (UV) light. Wavelengths around 260 nm are used because these are absorbed by the purine and pyrimidine components of nucleic acids, as well as certain aromatic amino acids in proteins. The absorbed energy causes a rupture of the chemical bonds, so that normal cellular function is impaired

UV lamps are commonly found in food preparation areas, operating theatres and specialist areas such as tissue culture facilities, where it is important to prevent contamination. Because they are also harmful to humans (particularly the skin and eyes), UV lamps can only be operated in such areas when people are not present. UV radiation has very poor penetrating powers; a thin layer of glass, paper or fabric is able to impede the passage of the rays. The chief application is therefore in the sterilisation of work surfaces and the surrounding air, although it is increasingly finding an application in the treatment of water supplies. Ionising radiations have a shorter wavelength and much higher energy, giving them greater penetrating powers. The effect of ionising radiations is due to the production of highly reactive free radicals, which disrupt the structure of macromolecules such as DNA and proteins. Surgical supplies such as syringes, catheters and rubber gloves are commonly sterilised employing gamma (γ ) rays from the isotope cobalt 60 (60Co). Gamma radiation has been approved for use in over 40 countries for the preservation of food, which it does not only by killing pathogens and spoilage organisms but also by inhibiting processes that lead to sprouting and ripening. The practice has aroused a lot of controversy, largely due to concerns about health and safety, although the first patent applications for its use date back nearly a hundred years! Although the irradiated product does not become radioactive, there is a general suspicion on the part of the public about anything to do with radiation, which has led to its use on food being only very gradually accepted by consumers. Gamma radiation is used in situations where heat sterilisation would be inappropriate, because of undesirable effects on the texture, taste or appearance of the product. This mainly relates to fresh produce such as meat, poultry, fruit and vegetables. Irradiation is not suitable for some foodstuffs, such as those with a high fat content, where unpleasant tastes and odours result. Ionising radiations have the great advantage over other methods of sterilisation that they can penetrate packaging.

Filtration:

Many liquids such as solutions of antibiotics or certain components of culture media become chemically altered at high temperatures, so the use of any of the heat regimes described above is not appropriate. Rather than killing the microorganisms, an alternative approach is simply to isolate them. This can be done for liquids and gases by passing them through filters of an appropriate pore size. Filters used to be made from materials such as asbestos and sintered glass, but have been largely replaced by membrane filters, commonly made of nitrocellulose or polycarbonate (Figure 13.3). These can be purchased ready-sterilised and the liquid passed through by means of pressure or suction. Supplies of air or other gases can also be filter-sterilised in this way. A pore size of 0.22µm is commonly used; this will remove bacteria plus, of course, anything bigger, such as yeasts; however, mycoplasma and viruses are able to pass through pores of this size. With a pore size 10 times smaller than this, only the smallest of viruses can pass through, so it is important that an appropriate pore size is chosen for any given task. A drawback with all filters, but especially those of a small pore size, is that they can become clogged easily. Filters in general are relatively expensive, and are not the preferred choice if alternative methods are available. High efficiency particulate air (HEPA) filters create clean atmospheres in areas such as operating theatres and laboratory laminar-flow hoods.

Figure2: Membrane filtration. Membrane filters are used to sterilise heat-labile substances. They are available in a variety of pore siz

Control of microrganisms by chemicals

Chemical agents that control microbial growth Chemical agents are used to reduce the growth of microorganisms of inanimate objects and on living tissue.

Phenol and Phenolic compounds

Lister first introduced phenol in aseptic surgery in 1867. Phenols are derivatives of benzene and have a hydroxyl group (-OH) attached to the benzene ring. Phenol kills microorganisms by denaturing proteins and destabilizing cell membranes. It is bacteriocidal, fungicidal, and virucidal at high concentrations, but is not effective against bacterial endospores, and is effective against many potential pathogens. It is used to disinfect garbage cans, surgical operating facilities, laboratory equipment, feces, urine, and sputum. Phenol is now no more used as a disinfectant because phenol is very expensive, fumes are lethal and derivatives of phenol are less expensive and more effective than phenol. An antimicrobial action of phenolic compounds is directed to inactivation of cellular enzymes. Phenolic compounds are antimicrobial because they increase membrane permeability, precipitate of cell proteins, and inactivate of enzymes and cause cell death. The most commonly used phenolic derivatives are cresols and bisphenols. Cresols are formed by adding methyl groups to phenol. Para-cresol is used for the preservation of wood products. Bisphenols are produced by combining two phenol molecules. Lysol is a combination of cresol and soap, which has about the same spectrum of activity as phenol, but is much less toxic to skin. Lysol is used for the disinfection of inanimate objects. Other cresols include resorcinol, hexylresorcinol, and hexachlorophene. Hexachlorophene soaps were once widely utilized as antiseptic soaps by health-care personnel for hand washing and the bathing of newborn infants, but have been now discarded, since it was found that this phenolic could be absorbed through the skin and potentially cause birth defects. The mixture of hexylresorcinol, glycerin and water is widely used as general antiseptics in mouth wash, gargles and cough drops. It is also used in the body care products such as soaps, oils and creams to control the skin microflora

b) Halogens Halogen elements:, iodine (I2), chlorine (CI2), bromine and fluorine in the Free State as well as their compounds are effective antimicrobial agents. Most commonly used halogens for the control of organisms are iodine and chlorine. Bromine and fluorine are strong irritants and very difficult to handle. a) Iodine: Iodine one of the oldest and most effective antiseptic. Iodine is effective against all kinds of bacteria, many endospores, various fungi and some viruses. It is usually applied to skin surface before surgical procedure & also used for wound treatment. Iodine kills bacteria as it combines with amino acid tyrosine of enzymes & inhibits their function. Iodine kills bacteria as it oxidizes– SH (sulfa hydryl) groups of certain amino acids those are important for maintaining structure of proteins. Following iodine preparations are available in market: Tincture: It is a solution of iodine in aqueous alcohol. Tincture, stains tissues and may causes local skin irritation and allergic reactions occasionally. It is topical antiseptic used prior to surgery, sometimes for burned and injured skin. Betadine: It is a combination of iodine and surface active agents. It release iodine slowly, non-stain forming and less irritating (Ex :) but it is effective like tincture as antimicrobiial agent. It is used to disinfect equipments and to prevent sepsis in burn wounds.

b) Chlorine: The several forms of chorine E.g. chlorine gas, sodium hypochlorite (NaOCl) and calcium Hypochlorite (Ca (OCl)2) are used for the purification drinking water. Chlorine gas is greenish greenish yellow in colour and very toxic. It is heavier than air and will therefore sink to the ground when released. It a very good disinfectant, but it is also toxic to humans. Chlorine gas is available as a compressed liquid, which is amber in color. Chlorine gas is the very cheaper form of chlorine. It causes respiratory irritation and it also irritates skin and mucus membranes. Exposure to high volumes of chlorine gas fumes can cause serious health problems leading to death. However, it is important that when chlorine gas enter the water, changes into hypochlorous acid and hypochlorite ions which are nontoxic forms to human. The typical dose of chlorine gas required for water treatment is 1-16 mg/L. Dose depends upon the quality of water to be treated however higher dose of chlorine is required. A compressed chlorine gas is used for disinfecting municipal drinking water, water in swimming polls and sewage. Calcium hypochlorite (CaOCl) is made up of the calcium salts of hypochlorous acid. It is produced by dissolving chlorine gas (Cl2) into a solution of calcium oxide (CaO) and sodium hydroxide (NaOH). Calcium hypochlorite is a white powder that comes either in tablet form as well as in a granular powder and is very stable. The chemical is very corrosive and requires proper handling. Calcium hypochlorite must also be kept away from moisture because the tablets/granular powder readily absorb moisture and will form (toxic) chlorine gas. Only 0.5-5 mg/L of calcium hypochlorite is required in the treatment of water. When calcium hypochlorite is added to water, hypochlorite and calcium ions are produced. Ca(OCl)2 --- Ca+2 + 2 OCl. Unlike chlorine gas which decreases pH, calcium hypochlorite increases the pH of the water (making the water less acidic). Calcium hypochlorite solution is used to disinfect equipments used in dairy and restaurant. Sodium hypochlorite (NaOCl) is made up of the sodium salts of hypochlorous acid that can be used as a disinfectant. It is produced when chlorine gas is dissolved into a sodium hydroxide solution. It is in liquid form, clear with a light yellow color, and has a strong chlorine smell. Sodium hypochlorite is extremely corrosive and must be stored in a cool, dark, and dry place. Sodium hypochlorite will naturally decompose; therefore it has less storage time i.e. not more than one month. It is very easier to handle as compare to other forms of chlorine. The amount of sodium hypochlorite required for water treatment is much less than the other two forms of chlorine, with 0.2-2 mg of NaOCl/L of water. NaOCl will also increase the pH of the water through the formation of hypochlorite ions. NaOCl = Na+ + OClHouse hold bleach contains 5. 25% sodium hypochlorite. This bleach is effective against AIDS viruses. Sodium hypochlorite (NaOCI) is house hold disinfectant. In houses for treatment of water for drinking, two drops of bleach are added to a liter of water (Four drops if water is cloudy) and the mixture is allowed to stand for 30 minutes. Thus, such treated water is considered safe for drinking under emergency conditions.

The chloramines are chlorine compounds used as disinfectants, sanitizers and antiseptics. The commonly used chloramine compounds are chloramine T and azochloramine. Chloramines are very stable and remain active in water for longer time slowly releasing chlorine giving prolonged action. Chloramine T Azochloramine Chloramine reacts with organic matter present in water. When large amounts of organic matter are present in the water, organic nitrogen reacts with chloramine forming organic chloramines. These compounds do not possess the disinfection property. Thus making it ineffective. Advantages of Chloramines as disinfectant are: it do not produce any off taste or smell and are relatively safe. The germicidal action of chlorine and its compounds is due to the formation of hypochlorous acid when free chlorine reacts with water. CI2 + H2O HCI + HOCI (Hypochlorous acid) NaOCl + H2O NaOH + HOCI (Hypochlorous acid) The hypochlorous acid formed is unstable molecule and further decomposed. HOCI HCI + [O] (Nascent oxygen) The nascent oxygen released in this reaction brings about microbial destruction by oxidation of cellular enzymes. Hypochlorous acid is most effective form of chlorine because it is neutral in electrical charge annd diffuses as rapidly as water through the cell wall.

3) Alcohols

Three aliphatic alcohols used as germicide includes methanol, ethanol & isopropanol. The germicidal action of alcohol is dependent on the molecular weight of the alcohol i.e. germicidal action increases with increase in molecular weight. Methanol is less germicidal than ethanol and ethanol is less germicidal than isopropyl alcohol and so on. But alcohols with molecular weight more than propyl alcohol are immiscible in water hence they are not used as disinfectant . The germicidal power of isopropanol is maximum because the rule is germicidal value increases with increase in molecular weight and is miscible in water. In practice solutions of 70 to 80 % alcohol in water is employed as germicide & percentage above 90% & below 50% is less effective.

High concentration of alcohol (above 80%) removes so much of water from cell so that the alcohol is unable to penetrate the cell. As the alcohol cannot penetrate in cell due to severe dehydration, high concentration of alcohol cannot kill the bacterial cells but can stop the multiplication. Thus high concentration of alcohol is microbiostatic. Whereas low concentration of alcohol partially dehydrates the cell wall and the penetration of alcohol in cell becomes easier. As a result cellular proteins precipitate and kill the bacterial cells. Spores are not destroyed by alcohol because water content of spores is less. Aliphatic alcohols are effective antimicrobial agents they are used for disinfection and also used as antiseptic. Alcohols are protein denaturant and solvents for lipids. Protein denaturation in cell is because alcohol is dehydrating agent and it remove water from cell. Removal of water from cell causes, protein denaturation & enzyme inactivation in cell. Due to denaturation of proteins of bacterial cell membrane and inactivation of enzymes, cells are killed. Lipids of membrane dissolve in alcohol which alters permeability of membranes and kills bacterial cells. Alcohols are unsatisfactory antiseptics because when applied to wounds they cause a coagulation of a layer of protein under which bacteria continues grow. Alcohol is used to reduce microbial flora of skin (to degerm skin) before hypodermic injections and, for disinfection of clinical thermometer.

4) Detergents (Surface active agents) Compounds which are primarily used for cleaning surface are called surface active agents (surfactants) .Surfactants reduce surface tension of water, For ex: common soaps & detergents (Synthetic detergents). Now – a- days synthetic detergents were developed in order to replace soap for cleaning . Soap has inability to form lather in hard or acidic water.

Soaps are prepared by boiling vegetable oil and fat with NaOH or KOH. The process of making soap is called saponification. Detergent or soap molecule has hydrophilic tail and hydrophobic head . During washing , tail go into grease and head go into water . When water is shaken, all tail molecules will go into grease and head dissolve in water. When water is shaken, all detergent molecules will remove the grease (dirt) away. Detergents are widely used in laundry, dish washing powder, shampoos, and many other preparations which are used for washing purpose. Now synthetic detergents consisting of cationic and anionic compounds have replaced soaps for many cleansing jobs. Soaps are lethal to spirochetes e.g. Treponema palladium. Detergents have strong surface tension reducing action; therefore they are microbicidal and microbiostatic. They are classified by their ionic (electrical charge) properties in water: anionic (negative charge), cationic (positive charge) and nonionic (no charge) detergent. a. Anionic detergent – They ionize and their detergent property resident in anion. e.g. Formula: [RSO3] - Na + (Sodium lauryl sulphate)

b. Cationic detergent

They ionize and their detergent property resident in cation. Most of cationic detergents are quaternary ammonium compounds. A group of cationic detergents which are Quaternary ammonium compounds is called quaternaries or quats. Zephiran, Cepacol are trade names of preparations of Quaternary ammonium compounds found in laboratory spray bottles. Quaternaries are more germicidal than anionic and non-ionic detergent. They are highly bactericidal against gram +ve bacteria and only less effective against gram –ve bacteria. These compounds are also active against fungi and protozoa but inactive against bacterial spores and viruses. Quaternaries have little toxicity for skin; they are extensively used as skin antiseptics and sanitizing agents in food industry. They are used for sterilization of surgical instruments since they are harmless to tissues. Quaternaries have some disadvantages i.e. they form foam, organic matter interferes with their effectiveness and they are neutralized by soaps and anionic detergents Quaternaries react with lipid of microbial cell membrane altering the permeability of cell membrane and causing leakage of essential cellular compounds. In addition denaturation of proteins and inactivation of enzymes by quaternaries plays role in its antimicrobial activity. They are used in the preparations of agents applied on skin for disinfection. They are also added as preservative in the ophthalmic and cosmetic preparations. They are used for the disinfection of floor, walls and other surfaces in hospitals and public utility places. They are also used in dairy, food and allied industries for effective sanitization. c. Non- ionic detergent – Those which do not ionize and does not possess significant antimicrobial property.

5) Heavy Metals: Mercury, silver and copper is the most commonly used heavy metals. The ability of very small amounts of heavy metals to exert antimicrobial activity is called oligodyanmic action (oligo means few). This action can be demonstration in laboratory by placing a clean piece of metal or a coin containing copper, silver or copper on a plate inoculate with microorganisms. After incubation, a zone of inhibition (no growth) surround the metal is seen. In a zone of inhibition heavy metal ions diffused from coin combine with –SH groups of enzymes of microbial cells and denature enzymes this kills the growth of microorganism. Most heavy metals either alone or in chemical compound are germicidal because they denature enzyme and other essential proteins of cell. Similarly, silver inactivates enzymes by binding with sulfhydryl groups , disrupts cell membranes, and inhibits disables proteins causing cell damage and death. Similarly, copper ion distorts the cell wall by bonding to negatively charged groups. Similarly mercury binds with sulfhydryl group of enzyme thus inactivating enzyme. Both gram positive and negative bacteria are affected by the oligodyanmic action of heavy metals. SilverSilver in a 1% concentration silver nitrite can be used to prevent possible gonococcal and certain bacterial infection of newborns. The chemical is placed in the eyes of infant immediately after birth, because if pathogens are present birth canal, resulting infection can cause blindness of newborn (Ophthalmia neonatorum). Since silver nitrate has been found not to be effective against number of potential bacterial pathogen, it is now replaced by antibiotic erythromycin. MercuryMercuric chloride an inorganic mercury compound has broad spectrum activity. It is used as antifungal in paints. CopperCopper sulphate is used to destroy algae that grow in water reservoirs. Copper compound (ß-hydroxyquinoline) is used as antifungal in paints.

6) Gaseous Chemosterilizers

Material that is adversely affected by heat and liquid are sterilized by gases. Sterilization by gases is called fumigation. Commonly used gases were SO2, Chlorine and formaldehyde which were widely employed for disinfection of rooms occupied by sick people. SO2 and chlorine are poisonous and damage the materials; they are now replaced by formaldehyde, ethylene oxide and ß-propiolactone. Formaldehyde (HCHO): This gas is generated by heating a concentrated solution of formaldehyde. Formaldehyde in aqueous solution is formalin. Vaporization of formaldehyde from formalin is used to sterilize an enclosed area. The fumes of formaldehyde are harmful and cause irritation of tissues and eyes. Since it penetrates only slightly it acts as surface disinfectant. It kills both vegetative cells and spores. It is a strong reducing agent and inactivates enzymes and cell constituents. It is used for the sterilization of certain instruments. Important use of formaldehyde is in the disinfection or sterilization of enclosed area such as operation theatre, working area in pharma and food industry. Ethylene oxide It is a liquid at a temperature below 10.80C, its boiling point. Above this temperature it vaporizes rapidly. In pure state, it is very toxic if inhaled and cause blisters, if its vapours remain in contact with skin. It is highly flammable even at low concentration. This problem is overcome by mixing it with CO2 or Freon; commercially a mixture of 10% ethylene oxide and 90% CO2 is sold as carboxide. Ethylene oxide acts by alkylation with many organic compounds including enzymes and many other proteins by replacing active H- atom of organic compound by an alkyl group. Alkylation of enzymes leads to inactivation of enzymes. + Enz-SH Enz-SH-CH2 CH2OH Active Inactive Ethylene oxide is very effective against microorganisms and their spores. The important property of Ethylene oxide is its penetration power; it can sterilize the material even after packaging without causing any damage to the material. Ethylene oxide is preferred over formaldehyde because of following reasons, 1. Although it is an expensive but readily available 2. It exhibit deep penetration. 3. It does not polymerise or condense on surfaces. 4. It is quickly removed by simple airing of treated materials. It has slow action upon microorganisms thus treatment is time consuming and is expensive. Ethylene Oxide (EtO) sterilization is mainly used to sterilize medical and pharmaceutical products that cannot support conventional high temperature steam sterilization - such as devices that incorporate electronic components, plastic packaging or plastic containers, disposable medical devices. Spices, herbs, condiments and some biological preparations can be sterilized by EtO within the purview local federal law. ß--PropiolactoneIt is colorless, pungent liquid at ambient temperature. Its boiling point is 167.30C and it is atomized into air. It is not flammable but causes blisters on the skin and irritation of eyes. It is an alkylating agent and acts through alkylation of carboxyl- and hydroxyl- groups causing inactivation of enzymes as like ethylene oxide. It kills microorganisms including spores. It is not explosive, non-corrosive and does not condense on surfaces. It has low penetration power and is a carcinogen. It has broad-spectrum activity as well as effective sporicidal agent. 0.2% is used to sterilize biological products. It is more effective in fumigation than formaldehyde. It is used to sterilize surgical instruments, vaccines and enzymes. 7) Chlorhexidine: Chlorhexidine is a cationic polybiguanide (bisbiguanide).

Chlorhexidine belongs to a group of medicines called antiseptic antibacterial agents. It is broad-spectrum antimicrobial drug (effective bactericidal agent against all categories of microbes, including bacteria, yeast, and viruses). It is an important antimicrobial in oral hygiene. Chlorhexidine molecules are positively charged (cations) and most bacteria and surface structures in the oral cavity including the surfaces of teeth and mucous membranes are negatively charged (anions). Thus chlorhexidine binds strongly to all these surface structures. When chlorhexidine binds to microbial cell walls it induces changes, damaging the surface structure, leading to an osmotic imbalance with consequent precipitation of cytoplasm causing cell death. It destroys all categories of microbes, not just bacteria, and there is little risk for the development of opportunistic infections. It is used to clean the skin after an injury, before surgery, or before an injection. Chlorhexidine is also used to clean the hands before any medical procedure. It works by killing or preventing the growth of bacteria on the skin. It is used as preservative in eye drops, active substance in wound dressings and antiseptic mouthwashes. It is also added as additive to creams, toothpaste, deodorants, and antiperspirants.

8) Aldehydes

Formaldehyde and glutaraldehydes are commonly used aldehydes for disinfection. Glutaraldehydes (CH2 (CH2CHO)2):It is used to disinfect medical and dental equipment. It is also used for industrial water treatment and as a preservative. It inhibit bacterial growth by combining with nucleic acids and proteins . It is used to disinfect hospital and laboratory equipments. Disinfection is achieved within 10 minutes but about 12 hours are required to kill spores.

INTRODUCTION TO MICROSOFT EXCEL

Microsoft Excel is a specific type of spreadsheet software developed by Microsoft. It is the industry standard for spreadsheets and is part of the Microsoft 365 (formerly Office) suite of productivity tools. While many spreadsheet programs exist (like Google Sheets or LibreOffice Calc), Excel is distinguished by its depth of features and widespread adoption in the business world.

A spreadsheet software is a computer application software that allows its user to organize, analyze, store and calculate data in a tabular format. It is used to develop personalized reports involving the use of extensive mathematical, financial, statistical and logical processing. It functions as a digital version of a paper accounting worksheet. The core structure of the interface consists of a grid made up of rows, columns and cells.

Uses of Spreadsheet

1. Create budgets,

2. Tabulate expenses,

3. Analyze survey results, and

4. Perform just about any type of financial analysis you can think of.

5. Create a variety of highly customizable charts.

6. Compiling mailing lists by using the row-and-column layout to store lists efficiently.

7. Accessing other data Import data from a variety of sources.

8. Creating graphical dashboards Summarize a large amount of business information in a concise format.

9. Creating graphics and diagrams

10. Use shapes and SmartArt to create professional-looking diagrams.

11. Automating complex tasks: Perform a tedious task with a single mouse click with Excel’s macro capabilities.

Microsoft Excel Interface/Ribbon

Excel interface revolves around the ribbon. The excel ribbon comprises of tabs, which contain groups of controls. The commands available in the Ribbon vary, depending upon which tab is selected. The Ribbon is arranged into groups of related commands. Here’s a quick overview of Excel’s tabs:

Home You’ll probably spend most of your time with the Home tab selected. This tab contains the basic Clipboard commands, formatting commands, style commands, commands to insert and delete rows or columns, plus an assortment of worksheet editing commands.

Insert Select this tab when you need to insert something into a worksheet—a table, a diagram, a chart, a symbol, and so on.

Page Layout This tab contains commands that affect the overall appearance of your worksheet, including some settings that deal with printing.

Formulas Use this tab to insert a formula, name a cell or a range, access the formula auditing tools, or control the way Excel performs calculations.

Data Excel’s data-related commands are on this tab, including data validation commands.

Review This tab contains tools to check to spell, translate words, add comments, or protect sheets.

View The View tab contains commands that control various aspects of how a sheet is viewed. Some commands on this tab are also available in the status bar.

Developer This tab isn’t visible by default. It contains commands that are useful for programmers. To display the Developer tab, choose File ➪ Options and then select Customize Ribbon. In the Customize the Ribbon section on the right, make sure that Main Tabs is selected in the drop-down control and place a checkmark next to Developer.

Help This tab provides ways to get help, make suggestions, and access other aspects of Microsoft’s community.

Add-Ins This tab is visible only if you loaded an older workbook or add-in that customizes the menu or toolbars. Because menus and toolbars are no longer available in Excel 2019, these user interface customizations appear on the Add-Ins tab. The preceding list contains the standard Ribbon tabs. Excel may display additional Ribbon tabs based on what’s selected or resulting from add-ins that are installed.

Structure of an Excel Workbook

A workbook is an excel file with atleast one worksheet, worksheet is inside a workbook and it is used in Excel documents which is a collection of cells organized in rows and columns. The worksheet is the working surface you interact with to enter data. It is one spreadsheet in a workbook. You perform the work you do in Excel in a workbook. The worksheet is divided into rows and columns

 Rows: Horizontal lines identified by numbers (1, 2, 3...).

 Columns: Vertical lines identified by letters (A, B, C...).

 Cells: The intersection of a row and a column (e.g., A1, B2) where data is entered. All positions on the worksheet are identified as cells where we have cell A1, A2, A3 etc and each one is referred to as a Cell Address.

A cell holds a single unit of information and an entry to a worksheet is value, label or formula.

Active Cell: Is the selected cell where data is entered when typing commences

A value is an actual numeric data content of a cell.

A label is a string of characters entered into a cell to serve as a heading

A formula is an expression consisting of cell addresses, numeric values and arithmetic operators

Chart: Any object that presents data in a visualor graphic manner

Range: Selected set of multiple cells.

Sort: Rearrangement of rows or columns according to certain criteria

Value: Any data in a one cell. It can also refer to the result of any formula

Zoom: Reduction or enlargement of screen of entire worksheet.

It is important to emphasise that in Excel each workbook contains one or more worksheets, and each worksheet consists of individual cells. Each cell can contain a number, a formula, or text. A worksheet also has an invisible drawing layer, which holds charts, images, and diagrams. Objects on the drawing layer sit over the top of the cells, but they are not in the cells like a number or formula. Each worksheet in a workbook is accessible by clicking the tab at the bottom of the workbook window.

Other examples of spreadsheet packages are Lotus 1-2-3, Quattro, Multiplan, Framework, VisiCalc.

& How to open a new Workbook

Click the start icon on the left down of your pc. and if you cannot find the start icon then click all programs to see all programs. The Excel Starter startup screen appears, and a blank spreadsheet is displayed. In Excel Starter, a spreadsheet is called a worksheet, and worksheets are stored in a file called a workbook. Workbooks can have one or more worksheets in them. Click on blank workbook.

& How to save your workbook

1. Click the Save button on the Quick Access toolbar. (This button looks like an old-fashioned floppy disk, popular in the previous century.) Because the workbook hasn’t been saved yet and still has its default name, Excel responds with a Backstage screen that lets you choose the location for the workbook file. The Backstage screen lets you save the file to an online location or your local computer.

2. Click Browse. Excel displays the Save As dialog box.

3. In the File Name field, enter a name (such as Monthly Sales Projection). If you like, you can specify a different location.

4. Click Save or press Enter. Excel saves the workbook as a file. The workbook remains open so that you can work with it some more. (Foulkes, L.(2020)

Under the Save dialogue box, you can Save or Save As

Click the file and then the Save As, under the Save As, select the place you want to save your document to. In the file name box, write the name you want to save the document with and then save. When you Save, Excel assumes that the destination where the work will be saved is already predetermined.

WORKING WITH SUM() FUNCTION

The sum function adds values. you can add individual values, cell references or ranges, or a mix of all three. to do this, select a cell next to the numbers you want to sum, click auto sum on the home tab, press enter, and you're done. Remember to alight the whole figures you want to sum before clicking the sum button at the right corner of the ribbon.

WORKING WITH MIN() & MAX() FUNCTION

Excel MIN or MAX function returns the smallest or largest numeric value in a range of values respectively.MIN will return the minimum value in a given list of arguments while MAX will return the highest value in a given list of argument from a given set of numeric values, it will return the smallest or highest value respectively. To do this, select a cell below or to the right of the numbers for which you want to find the smallest or highest number. On the Home tab, in the Editing group, click the arrow next to AutoSum., click Min (calculates the smallest) or Max (calculates the largest), and then press ENTER.

WORK WITH AVERAGE()AND COUNT() FUNCTION

The same process as discussed earlier, after highlighting the fields you want to work on, click the arrow next to AutoSum > Average, and then press Enter.

Count function returns the count of numeric values (includes numbers and dates); To do this, the COUNT function will get the number of entries in a number field that is in a range or array of numbers.

Use the =count function to do this operation and highlight the fields you want to perform this function on and click ENTER. Count gives you the number of cells you are working on.

MEANING OF RESEARCH

Research in common parlance refers to a search for knowledge. Once can also define research as a scientific and systematic search for pertinent information on a specific topic.

In fact, research is an art of scientific investigation.

The Advanced Learner’s Dictionary of Current English lays down the

meaning of research as “a careful investigation or inquiry specially through search for new facts inany branch of knowledge

Research is an academic activity and as such the term should be used in a technical sense. According to Clifford Woody research comprises defining and redefining problems, formulating hypothesis or suggested solutions; collecting, organising and evaluating data; making deductions and reaching conclusions; and at last carefully testing the conclusions to determine whether they are fit for formulating hypothesis

OBJECTIVES OF RESEARCH

The purpose of research is to discover answers to questions through the application of scientific procedures. The main aim of research is to find out the truth which is hidden and which has not been discovered as yet.

Though each research study has its own specific purpose, we may think of research objectives as falling into a number of following broad groupings:

1. To gain familiarity with a phenomenon or to achieve new insights into it (studies with this objective in view are termed as exploratory or formulative research studies);

2. To portray accurately the characteristics of a particular individual, situation or a group (studies with this object in view are known as descriptive research studies);

3. To determine the frequency with which something occurs or with which it is associated with something else (studies with this object in view are known as diagnostic researchstudies);

4. To test a hypothesis of a causal relationship between variables (such studies are known as hypothesis-testing research studies

MOTIVATION IN RESEARCH

What makes people to undertake research? This is a question of fundamental importance. The possible motives for doing research may be either one or more of the following:

1. Desire to get a research degree along with its consequential benefits;

2. Desire to face the challenge in solving the unsolved problems, i.e., concern over practical problems initiates research;

3. Desire to get intellectual joy of doing some creative work;

4. Desire to be of service to society;

5. Desire to get respectability.

However, this is not an exhaustive list of factors motivating people to undertake research studies.

Many more factors such as directives of government, employment conditions, curiosity about new things, desire to understand causal relationships, social thinking and awakening, and the like may as well motivate (or at times compel) people to perform research operations.

TYPES OF RESEARCH

The basic types of research are as follows:

Descriptive vs. Analytical: Descriptive research includes surveys and fact-finding enquiries of different kinds. The major purpose of descriptive research is description of the state of affairs as it exists at present.

In social science and business research the term Ex post facto research is used for for descriptive research studies. The main characteristic

of this method is that the researcher has no control over the variables; he can only report what has happened or what is happening. Most ex post facto research projects are used for descriptive studies in which the researcher seeks to measure such items as, for example, frequency of shopping, preferences of people, or similar data. Ex post facto studies also include attempts by researchers to discover causes even when they cannot control the variables. The methods of research utilized in descriptive research are survey methods of all kinds, including comparative and correlational methods.

In analytical research, on the other hand, the researcher has to use facts or information already available, and analyze these to make a critical evaluation of the material.

(ii) Applied vs. Fundamental: Research can either be applied (or action) research or

fundamental (to basic or pure) research. Applied research aims at finding a solution for an immediate problem facing a society or an industrial/business organisation, whereas fundamental research is mainly concerned with generalisations and with the formulation of a theory.

“Gathering knowledge for knowledge’s sake is termed ‘pure’ or ‘basic’ research.”4 Research concerning some natural phenomenon or relating to pure mathematics are examples of fundamental research. Similarly, research studies, concerning human behaviour carried on with a view to make generalisations about human behaviour, are also examples of fundamental research, but research aimed at certain conclusions (say, a solution) facing aconcrete social or business problem is an example of applied research.

Research to identify social, economic or political trends that may affect a particular institution or the copy research (research to find out whether certain communications will be read and understood) or the marketing research or evaluation research are examples of applied research.

Thus, the central aim of applied research is to discover a solution for some pressing practical problem,

whereas basic research is directed towards finding information that has a broad base of applications and thus, adds to the already existing organized body of scientific knowledge.

(iii) Quantitative vs. Qualitative: Quantitative research is based on the measurement of quantity or amount. It is applicable to phenomena that can be expressed in terms of quantity.

Qualitative research, on the other hand, is concerned with qualitative phenomenon, i.e., phenomena relating to or involving quality or kind. For instance, when we are interested in investigating the reasons for human behaviour (i.e., why people think or do certain things), we quite often talk of ‘Motivation Research’, an important type of qualitative research.

This type of research aims at discovering the underlying motives and desires, using in depth interviews for the purpose.

Conceptual vs. Empirical: Conceptual research is that related to some abstract idea(s) or theory. It is generally used by philosophers and thinkers to develop new concepts or to reinterpret existing ones. On the other hand, empirical research relies on experience or observation alone, often without due regard for system and theory. It is data-based research, coming up with conclusions which are capable of being verified by observation or experiment.

We can also call it as experimental type of research. In such a research it is necessary to get at facts firsthand, at their source, and actively to go about doing certain things to stimulate the production of desired information. In such a research, the researcher must first provide himself with a working hypothesis or guess as to the probable results.

SIGNIFICANCE OF RESEARCH

All progress is born of inquiry. Doubt is often better than overconfidence, for it leads to inquiry, and inquiry leads to invention” is a famous Hudson Maxim in context of which the significance of research can well be understood. Increased amounts of research make progress possible.

Research inculcates scientific and inductive thinking and it promotes the development of logical habits of thinking and organization

2 .Research provides the basis for nearly all government policies in our economic system. For instance, government’s budgets rest in part on an analysis of the needs and desires of the people and on the availability of revenues to meet these needs.

3. Research is equally important for social scientists in studying social relationships and in seeking answers to various social problems. It provides the intellectual satisfaction of knowing a few things just for the sake of knowledge and also has practical utility for the social scientist to know for the sake of being able to do something better or in a more efficient manner

4. Research has its special significance in solving various operational and planning problems of business and industry. Operations research and market research, along with motivational research, are considered crucial and their results assist, in more than one way, in taking business decisions.

5. Research is the bedrock of all scientific and technological inventions and innovations

6. To those students who are to write a master’s or Ph.D. thesis, research may mean a careerism or a way to attain a high position in the social structure;

(7) To professionals in research methodology, research may mean a source of livelihood;

(8) To philosophers and thinkers, research may mean the outlet for new ideas and insights;

(9) To literary men and women, research may mean the development of new styles and creative work;

(10) To analysts and intellectuals, research may mean the generalisations of new theories.

Research Process

Before embarking on the details of research methodology and techniques, it seems appropriate to

present a brief overview of the research process. Research process consists of series of actions or

steps necessary to effectively carry out research and the desired sequencing of these steps.

Formulating the research problem:

There are two types of research problems, viz., those

which relate to states of nature and those which relate to relationships between variables. At the very outset the researcher must single out the problem he wants to study, i.e., he must decide the general area of interest or aspect of a subject-matter that he would like to inquire into. Initially the problem may be stated in a broad general way and then the ambiguities, if any, relating to the problem be resolved.

The best way of understanding the problem is to discuss it with one’s own colleagues or with those having some expertise in the matter.

Extensive literature survey:

Once the problem is formulated, a brief summary of it should be

written down. At this juncture the researcher should undertake extensive literature survey connected with the problem. For this purpose, the abstracting and indexing journals and published or unpublished bibliographies are the first place to go to. Academic journals, conference proceedings, government reports, books etc., must be tapped depending on the nature of the problem. In this process, it should

be remembered that one source will lead to another. The earlier studies, if any, which are similar to the study in hand should be carefully studied. A good library will be a great help to the researcher at this stage.

3. Development of working hypotheses: After extensive literature survey, researcher should state in clear terms the working hypothesis or hypotheses. Working hypothesis is tentative assumption made in order to draw out and test its logical or empirical consequences. As such the manner in which research hypotheses are developed is particularly important since they provide the focal point for research.

. Preparing the research design:

The research problem having been formulated in clear cut terms, the researcher will be required to prepare a research design, i.e., he will have to state the conceptual structure within which research would be conducted. The preparation of such a design facilitates research to be as efficient as possible yielding maximal information. In other words, the function of research design is to provide for the collection of relevant evidence with minimal expenditure of effort, time and money.