Is DES cipher not security anymore Essay Example | Topics and Well Written Essays - 250 words

Is DES cipher not security anymore - Essay Example Although DES are still being used as a means of encryption by many organizations and governments, DES has significantly deprecated and is no longer secure as just anyone with a little technical know-how and time can break into the cryptographic keys. However, this does not mean that DES cipher should never be used all. It only means that it is important to evaluate the value of the information to be protected, both to the attacker and to the owner, and fully grasp the nature of the risks before making the decision to use Data Encryption Standard (DES) cipher. According to Stallings (2006, p.73), DES may still provide security if used in situations involving no real threats such as when encrypting files on a family PC. In conclusion, in view of the contemporary threats, DES algorithm offers very little deterrence for any determined adversary and should never be considered to be secure. Using more efficient and stronger cryptographic algorithms such as Advanced Encryption Standard (AES) and 3DES among others may provide better

Nano Chemistry Essay Example for Free

Nano Chemistry Essay 1.1 Definition Nanochemistry is concerned with generating and altering chemical systems, which develop special and often new effects as a result of the laws of the nanoworld. The bases for these are chemically active nanometric units such as supramolecules or nanocrystals. Nanochemistry looks set to make a great deal of progress for a large number of industry sectors. Nanotechnology exists in the realm where many scientific disciplines meet. Achievements in physics are getting progressively smaller – from valves to electronics, down to microelectronics and quantum computing. It mirrors the downsizing in focus in the biological sciences, from cells to genomics. Conversely, achievements in chemistry have been converging into the nanometre range from below – from atoms and molecules to supramolecular chemistry. Nanochemisty focuses on the unique properties of materials in the 1–100 nm scale. The physical, chemical, electrical, optical and magnetic properties of these materialsare all significantly different from both the properties of the individual building blocks (individual atoms or molecules), and also from the bulk materials.Nanochemistry is a truly multidisciplinary field, forming a bridge between nanotechnology and biotechnology, spanning the physical and life sciences. The Nanochemistry Research Institute (NRI) at Curtin carries out world-class research to provide innovative solutions to energy and resources materials and manufacturing electronics agricultural environmental management, and health and medical industries Nanochemistry applications in the materials, resources and energy sectors range from the design of crystalline catalysts and the control of crystal size, morphology, phase and purity, to the design and use of additives to control crystallization and inhibit scale formation. In the biological field, control of chemistry at the supramolecular level can lead to the development of a wide variety of new and improved biomaterials, such as artificial bones and tissues, as well as new pharmaceuticals and improved methods of drug delivery.1 ENGINEERING, SCIENCE ‘‘We are like dwarfs on the shoulders of giants, so that we can see more than they.’’ Bernard of Chartres, 12th century with nanoscience being the discipline concerned with making, manipulating and imaging materials having at least one spatial dimension in the size range 1–1000 nm and nanotechnology being a device or machine, product or process, based upon individual or multiple integrated nanoscale components, then what is nanochemistry? In its broadest terms, the de.ning feature of nanochemistry is the utilization of synthetic chemistry to make nanoscale building blocks of different size and shape, composition and surface structure, charge and functionality. These building blocks may be useful in their own right. Or in a self-assembly construction process, spontaneous, directed by templates or guided by chemically or lithographically de.ned surface patterns, they may form architectures that perform an intelligent function and portend a particular use.2 1.2 Objective of nanochemistry Creating nanoparticles Allowing properties of nanosystems to evolve, manipulating and controlling them Encapsulating and transporting materials (e.g. deodorant with nanodroplets)4 1.3 Nanochemistry used in: Cosmetics, e.g. sunscreen, toothpaste, skincare products Sanitary ware Built-in ovens and baking trays Gas-tight packaging Screens, photographic films Separating technology for waste water treatment and food production Catalysers for chemical reactions Exhaust purification5 It is also used in formation of :- Commercialization of nanochemicals Nanooxides of precious, ferromagnetic, rare metals (Ti, Zr etc.) Nanopolymers and membranes Nanomaterials (cement, fertilizers) Nanopowders in chemical applications Nanogreen chemistry Nano energy applications Environmental applications of nanotechnology When thinking about self-assembly of a targeted structure from the spontaneous organization of building blocks with dimensions that are beyond the sub-nanometer scale of most molecules or macromolecules, there are five prominent principles that need to be taken into consideration. These are: (i) building blocks, scale, shape, surface structure, (ii) attractive and repulsive interactions between building blocks, equilibrium separation, (iii) reversible association–dissociation and/or adaptable motion of building blocks in assembly, lowest energy structure, (iv) building block interactions with solvents, interfaces, templates, (v) building-blocks dynamics, mass transport and agitation. A challenge for perfecting structures made by this kind of self-assembly chemistry is to .nd ways of synthesizing (bottom-up) or fabricating (top-down) building blocks not only with the right composition but also having the same size and shape. No matter which way building blocks are made they are never truly monodisperse, nless they happen to be single atoms or molecules. There always exists a degree of polydispersity in their size and shape, which is manifest in the achievable degree of structural perfection of the assembly and the nature and population of defects in the assembled system. Equally demanding is to make building blocks with a particular surface structure, charge and functionality. Surface properties will control the interactions between building blocks as well as with their environment, which ultimately determines the geometry and distances at which building blocks come to equilibrium in a self-assembled system. Relative motion between building blocks facilitates collisions between them, whilst energetically allowed aggregation deaggregation processes and corrective movements of the self-assembled structure will allow it to attain the most stable form. 6 Providing the building blocks are not too strongly bound in the assembly it will be able to adjust to an orderly structure. If on the other hand the building blocks in the assembly are too strongly interacting, they will be unable to adjust their relative positions within the assembly and a less 1 ordered structure will result. Dynamic effects involving building blocks and assemblies can occur in the liquid phase, at an air/liquid or liquid/liquid interface, on the surface of a substrate or within a template co-assembly. As this text describes, building blocks can be made out of most known organic, inorganic, polymeric, and hybrid materials. Creative ways of making spheres and cubes, sheets and discs, wires and tubes, rings and spirals, with nm to cm dimensions, abound in the materials self-assembly literature. They provide the basic construction modules for materials self-assembly over all scales, a new way of synthesizing electronic, optical, photonic, magnetic materials with hierarchical structures and complex form, which is the central theme running throughout this chapter. A .owchart describing these main ideas is shown in igure 1. Nano-, a pre.x denoting a factor, its origin in the Greek nanos, meaning dwarf. The term is often associated with the time interval of a nanosecond, a billionth of a second, and the length scale of a nanometer, a billionth of a meter or 10 A  ° . In its broadest terms, nanoscience and nanotechnology congers up visions of making, imaging, manipulating and utilizing things really small. Feynman’s prescient nano world ‘‘on the head of a pin’’ inspires scientists and technologists to venture into this uncharted nano-terrain to do something big with something small.7 1.4 Large and Small Nanomaterials It was not so long ago in the world of molecules and materials that 1 nm (1 nm  ¼ 10 A  ° ) was considered large in chemistry while 1 m m (1 m m  ¼ 1000 nm  ¼ 10,000 A  ° ) was considered small in engineering physics. Matter residing in the ‘‘fuzzy interface’’ between these large and small extremes of length scales emerged as the science of nanoscale materials and has grown into one of the most exciting and vibrant fields of endeavor, showing all the signs of having a revolutionary impact on materials as we know them today. In our time, ‘‘nano’’ has left the science reservation and entered the industrial technology consciousness and public and political perception. Indeed, bulk materials can be remodeled through bottom-up synthetic chemistry and top-down engineering physics strategies as nanomaterials in two main ways, the first by reducing one or more of their physical dimensions to the nanoscale and the second by providing them with nanoscale porosity. When talking about finely divided and porous forms of nanostructured matter, it is found that ‘‘nanomaterials characteristically exhibits physical and chemical properties different from the bulk as a consequence of having at least one spatial dimension in the size range of 1–1000 nm’’.

Hplc Analysis Of Aloe Vera Tablets Biology Essay

Hplc Analysis Of Aloe Vera Tablets Biology Essay The project work was aimed to achieve the quantitative determination of aloin and aloe emodin in the form of tablets by employing HPLC. The method used was reverse phase high performance liquid chromatography. Calibration curve method was used for the quantification of aloin and aloe emodin. The mobile phase was the mixture of acetonitrile and deionised water in the ratio of 60:40 respectively. The mobile phase was pumped at 1.5 ml/minute and the analyte was quantified at the wavelength of 220 and 296nm. The column used for separation was kromasil 5C18. Reverse phase Isocratic run of standard aloin and standard aloe emodin was done and the peaks obtained from their analysis were used to compare the test sample peaks. Aloe vera colax tablets manufactured by Aloe pura laboratories were used as the test sample tablets which were extracted with water, methanol, acetonitrile, methanol-water and acetonitrile-water. After extraction they were subjected for isocratic run in HPLC instrument a nd the data obtained were compared with that of the standard. CHAPTER 1 INTRODUCTION 1.1 Introduction to Aloe Vera Aloes is the dried juice of the leaves of Aloe barbadensis Miller, known as Curacao aloes, or of Aloe perryi Baker known as Socotrine aloes, or of Aloe ferox Miller and hybrids of the species of Aloe africana Miller and Aloe spicata Baker, known as Cape aloes belonging to the family Liliaceae. [2,3] The synonym of aloes is Aalwee, Aalwyn, Kumari, Star cactus, Aroe, Acibar, Babosa, etc. [1] Aloes is indigeneous to eastern and southern Africa and grown in Cape colony, Zanzibar and islands of Socotra. It is also cultivated in Caribbean islands, Europe and many parts of India, including North West Himalayan region. [2] All the varieties of aloe are the major sources of anthraquinone glycosides. The principal active composition of aloe is aloin, which is a mixture of glucosides, among which barbaloin is the chief constituent. It is chemically aloe-emodin anthrone C-10 glucoside and is water-soluble. [2] Barbaloin is a C- glycoside and it is not hydrolysed by heating with dilute acids or alkalies. Ferric chloride decomposes barbaloin by oxidative hydrolysis into aloe-emodin-anthrone, little aloe-emodin and glucose. [2] Along with barbaloin, aloes also contains isobarbaloin, b-barbaloin, aloe-emodin and resins. The drug also contains aloetic acid, homonataloin, aloesone, chrysophanic acid, chrysamminic acid, galactouronic acid, choline, choline salicylate, saponins, mucopolysaccharides, glucosamines, hexuronic acid, coniferyl alcohol, etc. [2] The amount of barbaloin in different commercial varieties varies to a large extent. Curacao aloes contain about 22 percent of barbaloin. Indian variety, generally Aloe vera contain very less quantity (3.5 to 4 percent). Curacao aloes contains two and half times quantity of aloe-emodin , compared to Cape-aloe-emodin. [2] The resin of aloe principally contains Aloesin. It is a type of C- glucosyl chromome. Aloesin is also responsible for purgative action of aloes. [2] Fig. 1 Fig. 2 Aloin [5] Aloe emodin [6] 1.2 Uses of Aloe Vera: Aloes is used as purgative. Its effect is mainly on colon. It has a stronger purgative action in the series of all crude drugs with anthracene glycosidal content. To counter effect the gripping action, it is given along with carminatives. [2] It facilitates the healing of any kind of skin wound, burn, or scald even speeding recovery time after surgery. [4] It is applied topically in acne, sunburn, frostbite (it appears to prevent decreased blood flow), shingles, screening out x-ray radiation, psoriasis, preventing scarring, rosacea, warts, wrinkles from aging, and eczema. [2, 4] It also seems to help prevent opportunistic infections in cases of HIV and AIDS due to its immune system stimulant properties. [4] It appears to be of help in cancer patients (including lung cancer) by cativating white blood cells and promoting growth of non- cancerous cells. [4] Aloe also appears to work on heartburn, arthritis, and rheumatism pain and asthma. [2, 4] It also lowers the blood sugar levels in diabetics. [2, 4] Other situations in which it appears to work when taken internally inclue congestion, internal worms, indigestion, stomach ulcers, colitis, hemorrhoids, liver problems such as cirrhosis and hepatitis, kidney infections, urinary tract infections, prostate problems, and as a general detoxifier. [2, 4] CHAPTER 2 HPLC 2.1 HPLC: Introduction and Instrumentation The technique of high performance liquid chromatography is so called because of its improved performance when compared to classical column chromatography. It is also called as high-pressure liquid chromatography since pressure is used when compared to classical column chromatography. Instead of a solvent being allowed to drip through a column under gravity, it is forced through under high pressure of up to 400 atmospheres. For the separation, identification and quantification of compounds, this method is frequently used in biochemistry and analytical chemistry. [11, 12] The development of HPLC from classical column chromatography can be attributed to the development of smaller particle sizes. Smaller particle size is important since they offer more surface area over the conventional larger sizes. [7] 1960s 40 to 60m 1970s 10 to 20m 1980s 5 to 10m 1990s 1 to 3m A porous particle of 5m offers a surface area of 100-860 sq.metres/gram with an average of 400 sq.metres/gram. These offer very high plate counts upto 100,000/metre. Table 1: Comparison of classical column chromatography with HPLC [7] Parameter Classical column chromatography HPLC Stationary phase particle size Large 60-200m Small 3-20m Column size Length x int. diameter Large 0.5-5m x 0.5-5cm i.d. Small 5-50cm x 1-10mm i.d. Column material Glass Mostly metal Column packing pressure Slurry packed at low pressure often gravity Slurry packed at high pressure >5000 psi Operating pressure Low ( High (500 3000 psi) Flow rates Low to very low Medium to high (Often >3ml/min) Sample load Low to medium (g/mg) Low to very low (mg) Parameter Classical column chromatography HPLC Cost Low High Detector flow cell volume Large 300 to 1000ml Low 2 to 10ml Column efficiency i.e. Resolving power (Low) Theoretical plates per meter (High) often >100,000 Plates per meter Types of stationary phases available Limited range Wide range Scale of operation Preparative scale Analytical and preparative scale 2.2 Types of HPLC techniques [7, 9, 10, 11, 12] Based on Modes of Chromatography There are two modes viz. Normal phase mode and Reverse phase mode. These modes are based on the polarity of stationary phase and mobile phase. Before explaining the modes, it is important to know the interactions, which occur between solute, stationary and mobile phase. Polar Polar interaction or affinity is more Nonpolar Nonpolar interaction or affinity is more Polar Nonpolar interaction or affinity is less Normal phase mode: In normal phase mode, the stationary phase (eg. Silica gel) is polar in nature and the mobile phase is non-polar. In this technique, non-polar compounds travel faster and are eluted first. This is because of less affinity between solute and stationary phase. Polar compounds are retained for longer time in the column because of more affinity towards stationary phase and take more time to be eluted from the column. This is not advantageous in pharmaceutical applications since most of the drug molecules are polar in nature and takes longer time to be eluted and detected. Hence this technique is not widely used in pharmacy. Reverse phase mode: In reverse phase technique, a non-polar stationary phase is used. The mobile phase is polar in nature. Hence polar components get eluted first and non-polar compounds are retained for a longer time. Since most of the drugs and pharmaceuticals are polar in nature, they are not retained for a longer time and eluted faster, which is advantageous. Different columns used are ODS (Octadecyl silane) or C18, C8, C4, etc. Common reverse phase solvents are methanol, acetonitrile, tetrahydrofuran and water. Based on principle of separation Adsorption chromatography Ion exchange chromatography Ion pair chromatography Size exclusion or Gel permeation chromatography Affinity chromatography Chiral phase chromatography Each of the above technique is described in brief as follows: Adsorption chromatography: The principle of separation is adsorption. Separation of components takes place because of the difference in affinity of compounds towards stationary phase. This principle is seen in normal phase as well as reverse phase mode, where adsorption takes place. Ion exchange chromatography: The principle of separation is ion exchange, which is reversible exchange of functional groups. In ion exchange chromatography, an ion exchange resin is used to separate a mixture of similar charged ions. For cations, a cation exchange resin is used. For anions, an anion exchange resin is used. Ion pair chromatography: In ion pair chromatography, a reverse phase column is converted temporarily into ion exchange column by using ion pairing agents like pentane or hexane or heptane or octane sulphonic acid sodium salt, trtramethyl or tetraethyl ammonium hydroxide, etc. Size exclusion or gel permeation chromatography: In this type of chromatography, a mixture of components with different molecular sizes is separated by using gels. The gel used acts as molecular sieve and hence a mixture of substances with different molecular sizes is separated. Soft gels like agarose , dextran or polyacrylamide are used. Semi rigid gels like polystyrene, alkyl dextran in non-aqueous medium are also used. The mechanism of separation is by steric and diffusion effects. Affinity chromatography: Affinity chromatography uses the affinity of the sample with specific stationary phases. This technique is mostly used in the field of Biotechnology, Microbiology, Biochemistry, etc. Chiral phase chromatography: Separation of optical isomers can be done by using chiral stationary phases. Different principles operate for different types of stationary phases and for different samples. The stationary phases used for this type of chromatography are mostly chemically bonded silica gel. Based on elution technique 1. Isocratic separation: In this technique, the same mobile phase combination is used throughout the process of separation. The same polarity or elution strength is maintained throughout the process. In this technique, the peak width increases with retention time linearly according to the equation for N, the number of theoretical plates. Gradient separation: In this technique, a mobile phase combination of lower polarity or elution strength is used followed by gradually increasing the polarity or elution strength. One example is a gradient starting at 10% acetonitrile and ending at 90% acetonitrile after 25 minutes. The two components of the mobile phase are termed as A and B. Where A is the weak solvent and B is the strong solvent. Weak solvent allows the solute to elute slowly while strong solvent rapidly elutes the solutes from the column. A is usually water where as B is an organic solvent which is miscible with water such as acetonitrile, methanol, THF or isopropanol. Based on scale of operation 1. Analytical HPLC: Where only analysis of the samples are done. Recovery of the samples for reusing is normally not done, since the sample used is low. Eg. mg quantities. 2. Preparative HPLC: Where the individual fractions of pure compounds can be collected using fraction collector. The collected samples are reused eg. Separation of few grams of mixtures by HPLC. Based on type on analysis 1. Qualitative analysis: Which is used to identify the compound, detect the presence of impurities, to find out the number of components, etc. This is done by using retention time values. 2. Quantitative analysis: Which is done to determine the quantity of the individual or several components in a mixture. This is done by comparing the peak area of the standard and sample. 2.3 Principle of separation in HPLC: [7, 9] The principle of separation in normal phase and reverse phase mode is adsorption. When a mixture of components is introduced in to a HPLC column, they travel according to their relative affinities towards the stationary phase. The component, which has more affinity towards the adsorbant, travels slower. The component, which has less affinity towards the stationary phase, travels faster. Since no two components have the same affinity towards the stationary phase, the components are separated. 2.4 Instrumental Requirements [7, 9, 10, 12] Pumps solvent delivery system Mixing unit, gradient controller and solvent degassing Injector Manual or auto injectors Guard columns Detectors Recorders and integrators Fig. 3 The schematic diagram of HPLC [13] 1. Pump Solvent delivery system The solvents or mobile phases used must be passed through the column at high pressure at about 1000 to 3000 psi. This is because as the particle size of stationary phase is few m (5 10m), the resistance to the flow of solvent is high. Hence such high pressure is recommended. There are different types of pumps available. They are mechanical pumps and pneumatic pumps. A mechanical pump operates with constant flow rate and uses a sapphire piston. This type of pump is used in analytical scale. Pneumatic pumps operate with constant pressure and use highly compressed gas. The solvents used must be of high purity, preferably HPLC grade and filtered through 0.45m filter. Check valves: These are present to control the flow rate of solvent and back pressure. Pulse dampners: These are used to dampen the pulses observed from the wavy baseline caused by the pumps. 2. Mixing unit, gradient controller and solvent degassing Mixing unit is used to mix solvents in different proportions and pass through the column. There are two types of mixing units. They are low pressure mixing chamber, which uses helium for degassing solvents. High pressure mixing chamber does not require helium for degassing solvents. Mixing of solvents is done either with a static mixer, which is packed with beads, or dynamic mixer, which uses magnetic stirrer and operates under high pressure. Gradient controller In an isocratic separation, mobile phase is prepared by using pure solvent or mixture of solvents, i.e. solvent of same eluting power or polarity is used. But in gradient elution technique, the polarity of the solvent is gradually increased and hence the solvent composition has to be changed. Hence a gradient controller is used when two or more solvent pumps are used for such separations. Solvent degassing Several gases are soluble in organic solvents. When solvents are pumped under high pressure, gas bubbles are formed which will interfere with the separation process, steady baseline and the shape of the peak. Hence degassing of the solvent is important. This can be done by using any one of the following technique. Vacuum filtration which can remove all air bubbles. But it is not always reliable and complete. Helium purging i.e. by passing helium through the solvent. This is very effective but helium is expensive. Ultrasonication by using ultrasonicator, which converts ultra high frequency to mechanical vibrations. This causes the removal of air bubbles. 3. Injector Manual or auto injectors Several devices are available either for manual or auto injection of the sample. Different devices are: Septum injectors for injecting the sample through a rubber septum. This is not common, since the septum has to withstand high pressure. Stop flow (on line) in which the flow of mobile phase is stopped for a while and the sample is injected through a valve device. Rheodyne injector (Loop valve type) It is the most popular injector. This has a fixed volume loop like 20ml or 50ml or more. Injector has two modes, i.e. load position when the sample is loaded in the loop and inject mode, when the sample is injected. 4. Guard column Guard column has very small quantity of adsorbent and improves the life of the analytical column. It also acts as a prefilter to remove particulate matter, if any, and other material. Guard column has the same material as that of analytical column. Guard column does not contribute to any separation. 5. Analytical columns Analytical column is the most important part of HPLC technique, which decides the efficiency of separation. There are several stationary phases available depending upon the technique or mode of separation used. Column material: The columns are made up of stainless steel, glass, polyethylene and PEEK (Poly ether ether ketone). Most widely used are stainless steel, which can withstand high pressure. Latest ones are PEEK columns. Column length: Varies from 5cm to 30cm Column diameter: Ranges from 2mm to 50mm Particle size: From 1m to 20m Particle nature: Spherical, uniform sized, porous materials are used. Surface area: 1 gram of stationary phase provides surface area ranging from 100 860 sq.m with an average of 400 sq.m. Functional group: the functional group present in stationary phase depends on the type of chromatographic separation. In normal phase mode it contains the silanol groups (hydroxy group). In reverse phase mode it contains the following groups: C18 Octa Decyl Silane (ODS) column C8 Octyl column C4 Butyl column CN Nitrile column NH2 Amino column For other modes of chromatography, ion exchange columns, gel columns, chiral columns, affinity chromatographic columns, etc. are available. 6. Detectors [7,9,10] Detectors used depend upon the property of the compounds to be separated. Different detectors available are UV detector: This detector is based upon the light absorption characteristics of the sample. Two types of this detector are available. One is the fixed wavelength detector, which operates at 254nm where most drug compounds absorb. The other is the variable wavelength detector, which can be operated from 190nm to 600nm. Refractive index detector: This is a non-specific or universal detector. This is not much used for analytical applications because of low sensitivity and specificity. Flourimetric detector: This detector is based on the fluorescent radiation emitted by some class of compounds. The exitation wavelength and emission wavelength can be selected for each compound. This detector has more specificity and sensitivity. The disadvantage is that some compounds are not fluorescent. Conductivity detector: Based upon electrical conductivity, the response is recorded. This detector is used when the sample has conducting ions like anions and cations. Amperometric detector: This detector is based on the reduction or oxidation of the compounds when a potential is applied. The diffusion current recorded is proportional to the concentration of the compound eluted. This is applicable when compounds have functional groups, which can be either oxidised or reduced. This is a highly sensitive detector. Photodiode array detector (PDA detector): This is a recent one, which is similar to UV detector, which operates from 190 600nm. Radiations of all wavelengths fall on the detector simultaneously. The resulting spectrum is a 3-D or three-dimensional plot of Response Vs Time Vs Wavelength. The advantage is that the wavelength need not be selected, but the detector detects the responses of all the compounds. 7. Recorders and integrators Recorders: They are used to record the responses obtained from detectors after amplification, if necessary. They record the baseline and all the peaks obtained, with respect to time. Retention time for all the peaks can be found out from such recordings, but the area of individual peaks cannot be known. Integrators: Integrators are improved version of recorders with some data processing capabilities. They can record the individual peaks with retention time, height, and width of peaks, peak area, percentage of area, etc. Integrators provide more information on peaks than recorders. Now a days computers and printers are used for recording and processing the obtained data and for controlling several operations. 2.5 Parameters used in HPLC [7, 9, 10] Retention time (Rt): Retention time is the difference in the time between the point of injection and appearance of peak maxima. Retention time is the time required for 50% of a component to be eluted from a column. Retention time is measured in minutes or seconds. Retention time is also proportional to the distance moved on a chart paper, which can be measured in cm or mm. Retention volume (Vr): Retention volume is the volume of mobile phase required to elute 50% of the component from the column. It is the product of retention time and flow rate. Retention volume = Retention time x flow rate Separation factor (S): Separation factor is the ratio of partition co-efficient of the two components to be separated. It can be expressed and determined by using the following equation: S = Kb/ Ka = Ka/ Kb = (tb t0)/ (ta t0) Where, t0 = Retention time of unretained substance Kb, Ka= Partition coefficients of b and a tb, ta = Retention time of substance b and a S = depends on liquid phase, column temperature If there is more difference in partition coefficient between two compounds, the peaks are far apart and the separation factor is more. If the partition coefficients of two compounds are similar, then the peaks are closer and the separation factor is less. Resolution: Resolution is a measure of the extent of separation of two components and the baseline separation achieved. It can be determined by using the following formula: Rs = 2 (Rt1 Rt2)/ (W1 +W2) Theoretical plate (Plate theory): A theoretical plate is an imaginary or hypothetical unit of a column where distribution of solute between stationary phase and mobile phase has attained equilibrium. A theoretical plate can also be called as a functional unit of the column. HETP Height Equivalent to a Theoritical Plate [18, 7] A theoretical plate can be of any height, which decides the efficiency of separation. If HETP is less, the column is more efficient. If HETP is more, the column is less efficient. HETP can be calculated by using the following formula: HETP = length of the column/ number of theoretical plates HETP is given by Van Deemter equation HETP = A + (B/u ) + Cu Where, A = Eddy diffusion term or multiple path diffusion which arises due to packing of the column. This is unaffected by mobile phase velocity or flow rate. This can be minimised by uniformity in packing. B = Longitudinal diffusion term or molecular diffusion which depends on flow rate. C = Effect of mass transfer which depends on flow rate. u = Flow rate or velocity of the mobile phase. A column is efficient only when HETP is minimum. Hence an ideal flow rate corresponding to the minimum value of HETP is used. Efficiency (No. of theoretical plates): The number of theoretical plates expresses efficiency of a column. It can be determined by using the formula: n = 16 Rt ²/w ² Where, n = no. of theoretical plates Rt = retention time w = peak width at base Rt and w are measured in common units (mm or cm or minutes or seconds) and are proportional to the distances marked on chart paper. If the number of theoretical plates is high, the column is said to be highly efficient. If the number of theoretical plates is low, the column is said to be less efficient. For gas chromatographic columns, a value of 600/ metre is sufficient. But in HPLC, high values like 40,000 to 70,000/ metre are recommended. Asymmetry factor: A chromatographic peak should be symmetrical about its centre and said to follow Gaussian distribution. In such cases, the peak will be like an isosceles triangle. But in practice, due to some factors, the peak is not symmetrical and shows tailing or fronting. Fronting is due to saturation of stationary phase and can be avoided by using less quantity of sample. Tailing is due to more active adsorption sites and can be eliminated by support pre-treatment, more polar mobile phased increasing the amount of liquid phase. Asymmetry factor (0.95 to 1.05) can be calculated by using the formula: AF = b/a (b and a calculated at 5% or 10% of the peak height) 2.6 Applications of HPLC HPLC is being more widely used in several fields. Apart from its use in Pharmaceutical field, it is used in Chemical and Petrochemical industry, Environmental applications, Forensic applications, Biochemical separations, Biotechnology, Food analysis, etc. In fact there is no field where HPLC is not being used. It is a versatile and sensitive technique, which can be used in several ways. Some of them are listed below: Qualitative analysis: It is nothing but identification of compound. This is done by comparing the retention time of the sample as well as the standard. Under identical conditions, the retention time of the standard and the sample are same. If there is a deviation, then they are not the same compound. Checking the purity of the compound: By comparing the chromatogram of the standard and that of the sample, the purity of the compound can be inferred. If additional peaks are obtained, impurities are present and hence the compound is not pure. From the percentage area of the peaks obtained, the percentage purity can also be known. Presence of impurities: This can be seen by the presence of additional peaks when compared with a reference standard or reference material. The percentage of impurities may also be calculated from peak areas. Quantitative analysis: The quantity of a component can be determined by several methods like a. Direct comparison method By injecting a sample and standard separately and comparing their peak areas, the quantity of the sample can be determined. Area of the peak = peak height x width of peak at the half height A1/ A2 = a (W1/ W2) Where, A1 and A2 are peak area of sample and standard W1 and W2 are weight or concentration of sample and standard a is the response factor b. Calibration curve method: In calibration curve method, series of standards are used to determine their peak areas. A calibration curve of peak area Vs concentration of the drug is plotted. From the peak area of the unknown sample, by intrapolation, the concentration of the sample can be determined. This method has the advantage that errors, if any, are minimised. Internal standard method: In this method, a compound with similar retention characteristics is used. A known concentration of the internal standard is added to the sample solution whose concentration is not known. The chromatogram is recorded and their peak areas are determined. By using formula, the concentration of unknown solution is determined. Multicomponent analysis or Determination of mixture of drugs: Similar to the quantification of a single drug, multicomponent analysis can be done easily. The quantity of each component is determined by using any one of the above methods. Marketed formulations, which contain several drugs, can be determined quantitatively for each component. Isolation and identification of drugs or metabolites in urine, plasma, serum, etc. can be carried out. Isolation and identification of mixture of components of natural or synthetic origin. Biopharmaceutical and Pharmacokinetic studies. Stability studies. Purification of some compounds of natural or synthetic origin on preparative scale. 2.7 Limitations: [7, 10] The limitations of HPLC are that drugs have to be extracted from their formulations prior to analysis and large amounts of organic solvent waste are generated which are expensive to dispose off. CHAPTER 3 Experimental Selection 3.1 Aim of Project: The aim of this project was to carry out the quantitative determination of the active pharmaceutical ingredient aloin and aloe-emodin in the given Aloe Vera Colax tablets, manufactured by Aloe Pura laboratories and to compare the results with the given standard aloin and aloe-emodin. The technique used for analysis was reverse phase High Performance Liquid Chromatography method. The analysis was performed using standard calibration curve generated at 220 and 296nm wavelength. 3.2 Chromatographic equipment and conditions: All the chromatographic equipments and conditions, which were used to perform HPLC in a laboratory environment under simulated GLP compliance conditions, are listed below. 3.2.1 HPLC system 5 (used for isocratic elution): This system is manufactured by Agilent technologies 1200 series, whose model number is G1310A and the serial number is DE 62956545 3.2.2 Software used: The software used was Microsoft windows XP, Pentium D whose product number is G 2175 BA, revision code is B. 03. 01 and its registration number is CL1CE8DB0F 3.2.3 Column used: The column used was Kromasil 5C18 whose test number is 9203- 10344 3.2.4 Pipette used: The pipette used was Volac ultra (made in U.K.), S. No. 29186, Model: R680/ F, 0-1000 mL and Volac ultra (made in U.K.), S.No. 29185, Model: R680/ F, 500-5000 mL. 3.2.5 Analytical Balance: Mettler balance AC 88 was used to weigh the sample drug whose Biom

Marriage in A Doll House and A Streetcar Named Desire Essay -- compare

A couple’s marriage along with their struggles and problems can tell us a lot about their individual morals and what type of people they are. How someone handles themselves when they are in a battle or argument with their spouse can show the reader the person they are, their strengths, weaknesses and even their outlook on life. In these plays we are shown Torvald Helmer and Stanley Kowalksi’s ways of controlling their wives, their strengths, weaknesses and outlooks on life, or morals just by their actions. In A Doll House written in 1879 by Henrik Ibsen and in A Streetcar Named Desire written in 1947 by Tennessee Williams we are shown two different husbands, Torvald Helmer and Stanley Kowalksi that have an issue with having to be in control of their wives and their lives. In A Doll House we see a marriage between Torvald and Nora Helmer. Torvald is a major character in the play because he is the person that helps make the conflict of his wife Nora not wanting to tell him about the loan she took out and that she forged her father’s name in order to do it. Ibsen brings the issue of power in this marriage by always having Torvald in charge or the marriage. Torvald is a man that looks at his wife as an object and something that benefits him. He doesn’t really have a deep love for her, but instead is married to her because she is young and beautiful and society accepts and likes married men better than single men. He is very protective of his image and he always wants to look perfect and be perceived as perfect from other people, and Nora helps him achieve this. Torvald takes the role of the ruler, the spouse in charge by treating Nora like a child or a play toy, calling her names like â€Å"pet†, â€Å"squirrel†, or â€Å"Ca pri girl†. He also t... ...y made himself look out of hand himself and he also showed his lack of respect for Stella. In A Doll House by Henrik Ibsen and in A Streetcar Named Desire by Tennessee Williams we are shown two different husbands, Torvald Helmer and Stanley Kowalksi that have an issue with having to be in control of their wives and their lives. Torvald has to be in charge of everything in his life including his wife and in his job so that society will look at him as a â€Å"well off† man and he will always be looked at as stable and in control of every situation. Stanley is somewhat the same, needing to be in charge of his wife and how she acts so that his friends will look at him as â€Å"the tough guy that keeps his wife in line†. In both of these plays we are shown the husband’s strengths and the wives weaknesses and how their conflicts and the husband’s actions affect their marriages.

Body Fat and Eating Disorders Paper

The definition Of body composition is the body qualified amount Of fat to fat-free mass. Body composition is made up of two parts of mass. These parts are fat free mass and fat, fat free mass is made up of bones, muscle, water and tissue. Body fat is located inside the human body and protects the internal organs, provides sufficient energy, manages hormones which perform various functions in the body. When the person is considered obese or overweight the fat that they carry can cause a potential health risk.People who have standard body composition are usually healthier, move easier, function better and more efficient. Also humans who have ideal body composition have higher confidence than someone who has unsatisfactory body composition. A person who has more body fat than was standard IBM can be at risk for health issues. The health issues that can be related to obesity are cancer, diabetes, heart disease and etc. The obesity epidemic basically comes down to humans eating too much f ood and not doing enough exercise to burn calories, strengthens muscles and bones.The biggest factor is that humans are persuaded by fast food companies such as McDonald's, Burger King, Pizza Hut and other type of chains and restaurants. These companies invest billions of dollars in advertising to win consumers over and to spend money on their product. While the companies are making money, human beings are also gaining weight. Fast food companies are also increasing portions such as a large, medium or extra-large fries. These fries are packed with salt and sodium. Another factor that does not help the obesity epidemic is how a person lives and manages their daily schedules.If a person works a desk job at different hours it can be hard to find time to exercise on a daily basis. Some health problems that are associated with anorexia nervous are loss of bone strength, tooth decay, thyroid gland issues, and dehydration, sensitive to cold, depression, and poor memory. Bulimia nervous can lead to dehydration, kidney failure, irregular heartbeat, and drug and alcohol abuse. Binge eating health problems are more in depth than anorexia nervous and bulimia. Binge eating can lead to diabetes, high blood pressure, high cholesterol, gall bladder disease, trouble breathing, cancer, and sleep robbers.The cause of eating disorders is still founded to be unknown. But through research scientist and doctors have looked at the patterns of the person who is having an eating disorder. Most eating disorders are due to confidence and personal image issues that the person is having. From a physiological standpoint, an eating disorder can lead to health problems such as an ulcer. From throwing up to much the person can tear the lining in the stomach which can lead to further digestion issues. Dehydration and vomiting can lead to electrolyte abnormalities, which includes low potassium and calcium.Going further these issues can lead to dysfunction in the cardiac muscle. Malnutrition can lead to the body creating less estrogen and growth hormone which can lead to Infertility. By having low levels of estrogen, low calcium, peak levels of stress, can result in bone loss.

Violence in Media Entertainment Essays

Violence in Media Entertainment Essays Violence in Media Entertainment Essay Violence in Media Entertainment Essay the ancient Egyptians entertained themselves with plays re-enacting the murder of their god Osiris and the spectacle, history tells us, led to a number of copycat killings. The ancient Romans were given to lethal spectator sports as well, and in 380 B. C. Saint Augustine lamented that his society was addicted to gladiator games and drunk with the fascination of bloodshed. Violence has always played a role in entertainment. But theres a growing consensus that, in recent years, something about media violence has changed. For one thing, theres more of it. Laval University professors Guy Paquette and Jacques de Guise studied six major Canadian television networks over a seven-year period, examining films, situation comedies, dramatic series, and childrens programming (though not cartoons). The study found that between 1993 and 2001, incidents of physical violence increased by 378 per cent. TV shows in 2001 averaged 40 acts of violence per hour. Francophone viewers experienced the greatest increase. Although physical violence on the three anglophone networks in the study increased by 183 per cent, on their francophone counterparts it increased by 540 per cent. One network, TQS, accounted for just under half (49 per cent) of all the physical violence on the networks studied. Paquette and de Guise also identified a disturbing increase in psychological violence, especially in the last two years. The study found that incidents of psychological violence remained relatively stable from 1993 to 1999, but increased 325 per cent from 1999 to 2001. Such incidents now occur more frequently than physical violence on both francophone and anglophone networks. Canadians are also heavily influenced by American programming. Paquette and de Guise found that over 80 per cent of the TV violence aired in Canada originates in the U. S. They speculate that francophone networks and stations may have a higher incidence of violence because they broadcast more movies, and this, in turn may be due to lower production budgets. Canadian-made violence is most likely to appear on private networks, which broadcast three times as many violent acts as public networks do. Overall, 87. 9 per cent of all violent acts appear before 9 p. m. , and 39 per cent air before 8 p. m. at a time when children are likely to be watching. More Graphic, More Sexual, More Sadistic Other research indicates that media violence has not just increased in quantity; it has also become much more graphic, much more sexual, and much more sadistic. Explicit pictures of slow-motion bullets exploding from peoples chests, and dead bodies surrounded by pools of blood, are now commonplace fare. Millions of viewers worldwide, many of them children, watch female World Wrestling Entertainment wrestlers try to tear out each others hair and rip off each others clothing. And one of the top-selling video games in the world, Grand Theft Auto, is programmed so players can beat prostitutes to death with baseball bats after having sex with them. The Globalization of Media Concerns about media violence have grown as television and movies have acquired a global audience. When UNESCO surveyed children in 23 countries around the world in 1998, it discovered that 91 per cent of children had a television in their home and not just in the U. S. , Canada and Europe, but also in the Arab states, Latin America, Asia and Africa. More than half (51 per cent) of boys living in war zones and high-crime areas chose action heroes as role models, ahead of any other images; and a remarkable 88 per cent of the children surveyed could identify the Arnold Schwarzenegger character from the filmTerminator. UNESCO reported that the Terminator seems to represent the characteristics that children think are necessary to cope with difficult situations. Violence Without Consequences or Moral Judgment The notion of violence as a means of problem solving is reinforced by entertainment in which both villains and heroes resort to violence on a continual basis. The Center for Media and Public Affairs (CMPA), which has studied violence in television, movies and music videos for a decade, reports that nearly half of all violence is committed by the good guys. Less than 10 per cent of the TV shows, movies and music videos that were analyzed contextualized the violence or explored its human consequences. The violence was simply presented as justifiable, natural and inevitable the most obvious way to solve the problem. PG: Parental Guidance? Busy parents who want to protect their children from media violence have a difficult task before them. The CMPA found that violence appears on all major televis ion networks and cable stations, making it impossible for channel surfers to avoid it. Nightly news coverage has become another concern. In spite of falling crime rates across North America, disturbing images of violent crime continue to dominate news broadcasting. As news shows compete with other media for audiences, many news producers have come to rely on the maxim: If it bleeds, it leads. Violence and death, they say, keep the viewer numbers up. Good news doesnt. As well, movie ratings are becoming less and less trustworthy in terms of giving parents real guidance on shows with unsuitable content. PG-13 movies tend to make more money than R-rated films, and as a result, the industry is experiencing a ratings creep: shows that the Motion Picture Association of America would once have rated R are now being rated as PG-13, in order to increase box-office profits and rental sales. In movie theatres, there is some control over who watches what. But at home, theres little to stop children from watching a restricted movie on one of the many emerging specialty channels. Kids may also have access to adult video games at the local video store. In December 2001, the U. S. Federal Trade Commission reported that retailers allowed 78 per cent of unaccompanied minors, ages 13 to 16, to purchase video games rated mature. To make supervision even more problematic, American children often have their own entertainment equipment. According to the Annenberg Public Policy Center, 57 per cent of kids aged 8 to 16 have TVs in their bedrooms, and 39 per cent have gaming equipment. A Youth Subculture of Violence While many parents are concerned about the graphic violence and put-down humour in many kids shows, theres a growing subculture of violence that parental radar often misses. Music and Music Videos Music and music videos are pushing into new and increasingly violent territory. When singer Jordan Knight, formerly of the popular New Kids on the Block group, released a solo album in 1999, Canadian activists called for a boycott of the album because it included a song advocating date rape. And when the controversial rap artist Eminem came to Toronto in 2000, politicians and activists unsuccessfully called for the government to bar him from the country, on the grounds that his violent lyrics promoted hatred against women. For instance, his song Kim graphically depicts him murdering his wife; and Kill You describes how he plans to rape and murder his mother. In spite of (or perhaps because of) his promotion of violence, Eminem continues to be a commercial success. His Marshall Mathers release sold 679,567 copies in Canada in 2000, and was the years best-selling album. And The Eminem Show topped Canadian charts for months in 2002, selling, at one point, approximately 18,000 copies a week. Eminems success is not exceptional. Extremely violent lyrics have moved into the mainstream of the music industry. The Universal Music Group, the worlds largest music company, lists Eminem, Dr Dre and Limp Bizkit all of whom have been criticized for their violent and misogynist lyrics among its top-grossing artists. And Madonnas 2002 music video What It Feels Like For a Girlcontained such graphic violence that even MTV refused to air it more than once. Video Games Violence in general, and sexual violence in particular, is also a staple of the video game industry. The current trend is for players to be the bad guys, acting out criminal fantasies and earning points for attacking and killing innocent bystanders. Although these games are rated M, for mature audiences, its common knowledge that they are popular among pre-teens and teenaged boys. For example, players in Grand Theft Auto 3 (the best-selling game ever for PlayStation 2) earn points by carjacking, and stealing drugs from street people and pushers. In Carmageddon, players are rewarded for mowing down pedestrians sounds of cracking bones add to the realistic effect. The first-person shooter in Duke Nukem hones his skills by using pornographic posters of women for target practice, and earns bonus points for shooting naked and bound prostitutes and strippers who beg, Kill me. In the game Postal, players act out the part of the Postal Dude, who earns points by randomly shooting everyone who appears including people walking out of church, and members of a high school band. Postal Dude is programmed to say, Only my gun understands me. The level of violence in the gaming habits of young people is disturbingly high. In MNets 2001 study Young Canadians In A Wired World (which found that 32 per cent of kids 9 to 17 are playing video games every day or almost every day), 60 per cent cited action/combat as their favourite genre. Stephen Kline of Simon Fraser University reported similar findings in his 1998 study of over 600 B. C. teens. Twenty-five per cent of the teens he surveyed played between seven and 30 hours a week and when asked for their one favourite game, their choice was overwhelmingly in the action/adventure genre. Web Sites Virtual violence is also readily available on the World Wide Web. Children and young people can download violent lyrics (including lyrics that have been censored from retail versions of songs), and visit Web sites that feature violent images and video clips. Much of the violence is also sexual in nature. For example, the site Who Would You Kill? allows players to select real-life stars of television shows, and then describe how they would kill them off in the series. The entries frequently include bizarre acts of degradation and sexual violence. Murder is also a staple of the Web site newgrounds. com, which features a number of Flash movies showing celebrities being degraded and killed. When MNet surveyed 5,682 Canadian young people in 2001, the newgrounds site ranked twelfth in popularity among 11- and 12-year-old boys. Other popular sites such as gorezone. com and rotten. com feature real-life pictures of accident scenes, torture and mutilation. In 2000, rotten. com was investigated by the FBI for posting photographs depicting cannibalism. Many kids view these sites as the online equivalent of harmless horror movies. But their pervasive combination of violence and sexual imagery is disturbing. Gorezones front-page disclaimer describes the images on its site as sexually oriented and of an erotic nature and then warns viewers that they also contain scenes of death, mutilation and dismemberment. The disclaimer then normalizes this activity by stating, my interest in scenes of death, horrifying photos and sexual matters, which is both healthy and normal, is generally shared by adults in my community. Anecdotal evidence suggests that gore sites are well known to Canadian schoolchildren, although parents and teachers are often unaware of their existence. In MNets 2001 survey, 70 per cent of high school boys said that they had visited such sites. The presence of violence, degradation and cruelty in a range of media means that children are exposed to a continuum of violence, which ranges from the in-your-face attitude of shows like South Park to extreme depictions of misogyny and sadism. Young people generally take the lead when it comes to accessing new media but the MNet survey found that only 16 per cent of children say their parents know a great deal of what they do online. This is particularly problematic, given the results of a 1999 AOL survey which that found online activities are emerging as a central facet of family life; and that a majority of parents believe that