A Hydraulic Accumulator Energy Engineering Essay

A Hydraulic Accumulator Energy Engineering Essay A hydraulic accumulator is a device in which potential energy is stored in the form of a compressed gas or spring, or by a raised weight to be used to exert a force against a relatively incompressible fluid. They are used in fluid power systems to accumulate energy and to smooth out pulsations. Accumulators store energy when hydraulic system pressure is greater than the accumulator pressure and provide hydraulic energy when the accumulator pressure is greater than the system pressure. By storing and providing hydraulic energy, accumulators can be used as a primary power source. Accumulators are inherently dynamic devices, they function when configuration changes (actuators moving, valves opening, etc.) are occurring within a hydraulic system. Accumulators respond very fast to configuration changes, nearly instantaneously for gas accumulators. They are usually used in conjunction with a pump/motor in a hydraulic circuit. A hydraulic system utilizing an accumulator can use a smaller fl uid pump since the accumulator stores energy from the pump during low demand periods. The pump doesnt need to be so large to cope with extremes of demand, so that the supply circuit can respond more quickly to any temporary demand and to smooth pulsations. The capability and affect of the accumulator is determined by the overall volume of the accumulator and preload/pre-charge of the spring/gas. There are 4 types of accumulators: bladder, diaphragm bladder, piston (either spring or gas controlled) and metal bellows. The choice of accumulator to use in a given application depends on required speed of accumulator response, weight, reliability and cost. Pressurized gas accumulators will have the faster dynamic response and are reliable. Metal bellows accumulators are very reliable, but will not respond as fast as a pressurized gas accumulator. Accumulators with seals generally have the lowest reliability. Accumulators are either spherical or cylindrical in design. Bag, piston and metal bellows accumulators are cylindrical. Diaphragm accumulators may be spherical or cylindrical. Accumulators are usually manufactured into 2 halves which are either welded or threaded together. A fill port is installed at one end of a gas accumulator and the hydraulic connection fitting (with poppet valve, if required) is installed at the opposite end. For a spring accumulator, the non pressure sid e usually has a fitting that connects to the hydraulic reservoir (for seal leakage and to alleviate back pressure on a piston). Materials are usually steel, but accumulators may also be made from aluminium or a composite (filament wound) material. Compressed gas accumulators are by far the most common type; these gas accumulators take advantage of the fact that the gas is compressible. A gas accumulator has a gas pre-charge that is less than the nominal hydraulic system pressure. As hydraulic fluid enters the accumulator the gas is compressed to the nominal system pressure, which is an equilibrium position and represents the maximum amount of energy stored by the accumulator. As system hydraulic pressure drops, the gas will expand pushing hydraulic fluid back into the system. The gas pre-charge level is an important parameter for gas accumulators since the pre-charge and overall accumulator volume; determine the maximum amount of hydraulic energy that will be available to the system. The pre-charge is the pressure of the gas in the accumulator without hydraulic fluid in the fluid side. A gas accumulator is pre-charged with nitrogen gas when there is no hydraulic fluid in the accumulator to the desired pressure. The gas accumulator pre-charge is a very important variable for ensuring optimal accumulator performance and maintaining long life of the accumulator. Too high of a pre-charge pressure and the fluid volume capacity is reduced. Furthermore, if a bag accumulator charge is too high than the bag may hit the poppet valve which could damage the bag through repeated hits in service, or cause a fatigue failure in the poppet valve assembly. For a piston accumulator, the piston may be driven into the stops repeatedly affecting seals or cause a fatigue failure in the piston stop. Too low of a pre-charge pressure and the accumulator may not maintain desired minimum hydraulic system pressure. Also a low pre-charge pressure will allow a piston accumulator to repeatedly hit the up stops leading to premature failure of the accumulator. For a bag accumulator, the bag may be forced into an unnatural shape (e.g.,with folds) leading to bag damage and premature bag failure. When sizing an accumulator the pre-charge pressure is an input to the sizing process. However, once the accumulator is sized the minimum and maximum gas volumes should be computed (under worst case conditions) and analyzed to ensure piston stops are not hit or that a bag cannot fully collapse or expand completely in the accumulator. Bladder Accumulator A bladder accumulator consists of pressure vessel with an internal elastomeric bladder with pressurized nitrogen on one side and hydraulic fluid on the other side (system side). Figure 1 shows a bladder accumulator. It has 3 stages of operation: The accumulator is charged with nitrogen through a valve installed in the top. The accumulator will be pre-charged to nominal pressure when the pumps are not operating. Secondly when nominal hydraulic system pressure is applied the bag will be compressed to its fully compressed state. When the bag is fully compressed, the nitrogen pressure and the hydraulic pressure are equal. Finally as system pressure drops the bag expands, forcing fluid from the accumulator into the system. As the bag expands pressure in the bag decreases. The bag will continue to expand until the bag pressure equals the hydraulic pressure (which will be lower than nominal system pressure) or the bag fills the entire accumulator volume which is an undesirable situation. A poppet valve keeps the bag in accumulator from being pulled into the downstream tubing should the bag over-expand. If the bag was pulled into the downstream tubing, the accumulator would never recharge and normal flow from the pump would be constricted. The maximum flow rate of the accumulator is controlled by the opening area (orifice) and the pressure difference across the opening. Figure http://www.globalspec.com/NpaPics/18/146314_030520074661_ExhibitPic.JPGAccumulator, Bladder Typehttp://www.globalspec.com/NpaPics/18/146314_030520074661_ExhibitPic.JPG The main advantages of a bladder accumulator are fast acting, no hysteresis, not susceptible to contamination and consistent behaviour under similar conditions. Accumulators are easy to charge with the right equipment. Because there is no piston mass, the speed of the bladder accumulator is governed by the gas, which reacts very fast to changes in hydraulic system pressure. Hence bladder accumulators are the best choice for pressure pulsation damping. Also, the bladder attachment internal to the accumulator has proven to be very reliable in service. Of course there is always the potential for bladder failure, which is a failure that would not usually be detectable in service. Also, temperature differences on the gas will have some affect on performance. The main limitation of bladder accumulators is the compression ratio (maximum system pressure to pre-charge pressure) which is limited to approximately 4 to 1. Hence gas accumulators will be larger than other accumulators for the same flow requirements. The pre-charge pressure is typically set to approximately 80% of the minimum desired hydraulic system pressure. Diaphragm Accumulator A diaphragm accumulator is similar to bag accumulator except an elastomeric diaphragm is used in lieu of a bag. This would typically reduce the usable volume of the accumulator so the diaphragm accumulator may not have volume capacity of a bladder accumulator. A schematic of a diaphragm accumulator is shown in Figure 2. http://www.machinerylubrication.com/articles/200907/pg26b.gif Figure http://www.machinerylubrication.com/articles/200907/pg26b.gif The behaviour characteristics of a diaphragm accumulator are similar to a bag accumulator and have the same advantages and disadvantages. However a diaphragm accumulator may be spherical or cylindrical (or possibly other shapes) which may be an advantage in some installations. The main difference with bladder accumulators is an increased maximum compressions ratio (maximum system pressure to pre-charge pressure) of approximately 8 to 1. Piston Accumulator A gas piston accumulator is shown in Figure 3. A gas piston accumulator has a piston which slides against the accumulator housing on seals. On one side of the piston is nitrogen and on the other side is the hydraulic fluid and connection to the system. A fill port allows pressurization of the nitrogen. Accumulator, Piston Type Figure http://www.tobul.com/index.php?option=com_contenttask=viewid=13Itemid=27 A gas piston accumulator will not respond to transient pressures as fast as a bladder accumulator due to the mass of the piston (frequency characteristics depend on piston mass and spring characteristics of the nitrogen). However, a piston accumulator will have better damping due to hydraulic leakage (viscous damping) and friction between the piston and housing (coulomb friction seal friction). Piston accumulators may also be more prone to leakage than other types of accumulators due to the seals. Piston accumulators will generally provide higher flow rates than gas accumulators for equal accumulator volumes. This is because piston accumulators can accommodate higher pressure ratios (maximum system pressure to pre-charge pressure) than gas accumulators, up to 10 to 1, compared with bladder accumulator ratios of 4 to 1. The disadvantages of piston accumulators are that they are more susceptible to fluid contamination, have a lower response time than bladder (unless the piston accumulator is at a very high pressure) and will have hysteresis from the seal friction. The pre-charge for a gas piston accumulator is typically set to around 90% of minimum desired hydraulic system pressure. A schematic of a spring piston accumulator is shown in Figure Accumulator, Spring Type In a spring accumulator, the spring applies a force to a piston which compresses (or pressurizes) the fluid in the accumulator. As normal system pressure, the spring will be fully compressed. As system flow demands exceed the pump capacity, the spring will extend pushing the piston which in turn pushes fluid into the adjoining pipe. Hence the accumulator supplements pump flow. The maximum response time of the accumulator is set by the natural frequency, which is computed using Metal bellows accumulators are used where a fast response time is not critical yet reliability is important. Emergency brake accumulators are a good application for metal bellows accumulators. The metal bellows accumulator consists of a pressure vessel with a metal bellows assembly separating fluid and nitrogen. The accumulator is similar to a piston accumulator, except a metal bellows replaces piston and piston seals. Metal bellows accumulators are very reliable and long life components, and have a proven service history. Metal bellows accumulators are pre-charged by supplier and then permanently sealed leading to a maintenance free accumulator. Metal bellows accumulators will be slow in responding to pressure changes due to increased mass of piston and bellows. The advantages to the metal bellows type include exceptionally low spring rate, allowing the gas charge to do all the work with little change in pressure from full to empty, and a long stroke relative to solid (empty) height, which gives maximum storage volume for a given container size. The welded metal bellows accumulator provides an exceptionally high level of accumulator performance, and can be produced with a broad spectrum of alloys resulting in a broad range of fluid compatibility. Another advantage to this type is that it does not face issues with high pressure operation, thus allowing more energy storage capacity. Applications of Accumulators to KERS One of the main applications of hydraulic accumulators is storing energy. Hydro-pneumatic accumulators incorporate a gas in conjunction with a hydraulic fluid. The fluid has little dynamic power storage qualities. The fluid can only be reduced a small amount in volume even under high pressure. Therefore when only a small amount of the total contained volume is released, the pressure of the remaining fluid in the system will drop to zero. However, the relative incompressibility of a hydraulic fluid makes it ideal for fluid power systems and provides quick response to power demand. The gas, however working with the hydraulic fluid in the accumulator, can be compressed to high pressures and low volumes. Potential energy is stored in this compressed gas to be released upon demand. In the piston type accumulator the energy in the compressed gas exerts pressure against the piston separating the gas and hydraulic fluid. The piston in turn forces the fluid from the cylinder into the system a nd to the location where useful work will be accomplished. On this basis, with respect to all the types of accumulator a hydro-pneumatic accumulator would be ideal for storing the energy taken out of a bike whilst braking.. Of course the loss of pressurized gas in a sealed accumulator is a failure critical to safety when it plays such an important role as braking. A team of engineering students from university of Michigan undertook a project to use a hydro-pneumatic regenerative braking on a bicycle. It was a redevelopment of a heavier previous attempt to make a working prototype to fit within a 29 front wheel. They use a 0.5L accumulator and believed this to be sufficient in storing the required energy at a maximum working system pressure of 5000psi. They failed to test and thus supply conclusive results for the performance characteristics but through theoretical analysis they prescribe the key parameters fig. Figure Its weight is clearly impractical as it weighs almost as much as a conventional bike at 13kg. In terms of weight of a bicycle with respect to saving weight, it is more important to have lighter wheels than a lighter bike frame. This is because the rolling resistance is applied at the wheels although it carries half the overall weight of bike and rider a lighter wheel makes it easier to initially start a bike. Based on the team from michigans ( ) the following calculations outline the practicality of implementing a hydraulic KERS. Firstly for a hydraulic system to be implemented the storage must be addressed the capacity must be determined and pressures needed to store the kinetic energy. A bike braking from 20mph requires 5000J of energy to power. From Parkers website a manufacture of accumulator and motors parkers rate the ACP series accumulators at max pressure 5000psi, if assuming A hydraulic KERS must use a hydraulic motor to provide enough torque to drive the bike as well as provide enough resistive torque to be an effective brake. A bicycle travelling at 20mph on 26 wheels spins the motor through 18:1 gear ratio of the pump gear train which then spins the motor 4632rpm, corresponding to 4.52 N-m torques at 3000 psi. This translates to a braking torque of about 81.36 N-m applied to the main gear due to the 18:1 gear ratio. From this brake torque is an effective brake On release of pressure fully charged 5000 psi accumulator generates 7.57 N-m of torques. The 14:1 gear ratio of the motor gear train applies a 105 N-m torque to the main bicycle cluster gear. 7.57 N-m corresponds to around 800 rpm from its torque rpm curve, which turns the main gear at around 57 rpm due to the 14:1 gear ratio. This torque from fig can propel a bike at Conclusion The accumulator doesnt need to be an excessively large capacity to release enough energy to propel a bike 20mph, upon releasing the energy at a pre-charge of 3200psi. But a larger accumulator is needed for the accumulator to give more than one bursts using its full capacity. A hydraulic motor can produce 81.36N-m braking torque which is an effective brake. Furthermore an accumulator can power a hydraulic motor provide an accelerating torque to propel a bicycle. However based on the weight of the design from univerty of Michigan their prototype was 13kg, they used two accumulators plus they attached it to a bracket that probably contributed to the majority of the weight.

Standardization of Anti-diabetic Poly Herbal Formulation

Standardization of Anti-diabetic Poly Herbal Formulation 1. Introduction Now-a-days most of developed as well as developing countries use Ayurvedic medicines then they uses it in past. They avoid use of allopathic drugs because of high risk of adverse effects. So, for the sake of community it is important to standardize the dosage form available in market. Standardization of formulation is evidence that the formulation contains constituents which it says to be contained. In present work formulation containing Gymnemic acid and Resveratrol has been studied. This formulation is anti-diabetic. Gymnemic Acid (GYM) is major constituent isolated from leaves of plant Gymnema Sylvester belonging to family Asclepiadacea. (1) Plant has a property of masking the sugar test so it is known as â€Å"GURMAR†. Gymnemic acid is a triterpenoid saponin found in the leaves of Gymnema Sylvester. (2) Many studies have shown that oral administration of Gymnema extract reduces serum glucose level and improves glucose tolerance in mildly diabetic rats. (3) Administration of water extract of Gymnema sylvestre leaves was found to increase serum insulin level suggesting its insulin releasing effect. (4) Number of beta cells within pancreatic tissue were increased which suggests a restorative effect of the Gymnema extract on pancreatic tissue. (5) So, from above it is now known that Gymnemic acid has the ability to decrease blood glucose level in diabetic patient which ultimately relives Diabetes. Resveratrol (RES) (3,4†²,5-trihydroxy-trans-stilbene) is polyphenolic constituent isolated from plant Polygonum Cuspidatum belonging to family Polygnaceae. (6) It has been reported that Resveratrol has a variety of biological and pharmacological effects including antioxidant, anti-inflammatory, antiplatelet, anticarcinogenic effects, modulation of lipid metabolism and cardioprotection. (7) In pancreatic ÃŽ ²-cells, insulin secretion is linked to the oscillations in membrane potential, intracellular Ca2+ and metabolism. The variations in the ATP/ADP ratio control the conductance of ATP-dependent K+ channels leading to depolarization and periodic influx of Ca2+. The resultant membrane depolarization activates voltage dependent L-type Ca2+ channels and triggers intracellular Ca2+ release, elevating intracellular Ca2+ both in the cytosolic compartment and within the mitochondria, and thereby initiating insulin secretion. (8) From the survey of various literatures it is found that Gymnemic acid has been estimated by various analytical techniques like HPTLC, HPLC Gravimetery. (9) While Resveratrol had been estimated by HPLC and spectrometric techniques. (10) Not a single method is reported for the estimation of both constituents simultaneously. Present work has been focused on estimation of both constituents simultaneously. Here estimation of both constituents was done by UV-Visible spectrometry and HPTLC. For estimation of both constituents simultaneously UV-visible Spectrophotometric and HPTLC methods were developed and validated. Figure 1: Gymnemic acid Table 1: Gymnemic acid Group Figure 2: Resveratrol 2. Experimental Chemical Reagents Gymnemic acid relative Standard was extracted from the formulation. This relative standard was compared with standard obtained from Clearsynth TM Private Ltd (Andheri (w), Mumbai, India) . Then the prepared relative standard was used for methods. Same way, Resveratrol was extracted from formulation and then compared with standard Sigma-Aldrich constituent. Marketed formulation here used was Resveratrol plus (with Gymnemic acid) {Zenith Nutrition’s} containing 100mg Resveratrol and 500 mg Gymnemic acid per 2 capsules. All reagents for UV-Visible Spectrophotometry and HPTLC are Methanol, Chloroform, Ethanol, Glacial Acetic Acid, water and Benzoyl Chloride. Methanol, Chloroform and Ethanol used were analytical grade purchased from merk solutions. Triple distill water was made in laboratory by distillation assembly. Benzoyl Chloride was purchased from SD fines Chemicals. Instruments UV-Visible Spectrophotometric was developed on a Shimadzu UV-Vis double beam spectrophotometer, model 2400 PC series, with spectral width of 1 nm, wavelength accuracy of 0.5nm and a pair of 10 mm matched quartz cells (Shimadzu , Japan). The HPTLC instrumentation consisted of a Linomat V sample applicator with 100  µL Hamilton syringe and a TLC III scanner controlled by WinCATS software (Camag, Muttenz, Switzerland) Merck TLC plates coated with 60F254 silica gel on aluminum sheets were used as stationary phase. The plates were developed in a Camag 10 x 10 cm twin through chamber that was previously saturated for 20 minutes with mobile phase. Spectrometric Conditions GYM didn’t contain chromophore in structure so it has to be derivatized for UV-Visible detection. Benzoyl Chloride was used as derivatizing agent. The solutions of GYM RES were scanned in the spectrum mode from 200 to 400 nm, and from that 303nm for Gymnemic acid determination, 318.4 nm for Resveratrol determination and 349 nm for isoabsorptive point for Q ratio method were selected for simultaneous estimation. Chromatography Condition The solutions were spotted in the form of hands of 5 mm width on pre-coated silica gel 60F254 aluminum plates using a Camag 100  µL sample applicator syringe. They were activated at 110 oC in an oven for 20 minutes before sample application. A constant application rate 0.1 µL/s was applied and bandwidth was 9 mm between two bands. Spotted plates were developed in twin through chamber which is previously saturated for 20 minutes with mobile phase containing Chloroform: Methanol: Glacial acetic acid (13: 4: 0.5 %). The plates were developed for 8 cm run length. The plates were dried by hair dryer and then post derivatization done by dipping plates in Vanillin-Sulphuric acid solution. Then it is heated in hot air oven at 105oC for 5 minutes. Then plates were scanned at 575nm in TLC III scanner. Preparation of solutions Preparation of Standard solution for UV Resveratrol relative standard 10 mg was accurately weighed which is transferred to 10 ml clean volumetric flask. This much quantity was dissolved in 10 ml of ethanol to produce 1000 µg/ ml standard stock solution. From standard stock solution 1 ml is transferred to another 10 ml of volumetric flask and volume was made up with methanol to produce 100  µg/ ml working standard stock solution. Gymnemic acid relative standard 100 mg was accurately weighed which is transferred to 10 ml clean volumetric flask. This much quantity was dissolved in 10 ml of triple distill water to produce 10000  µg/ ml standard stock solution. From standard stock solution 1 ml was transferred to 10 ml volumetric flask diluted with methanol to produce 1000  µg/ ml working standard solution. Benzoyl chloride was diluted in ethanol first and then in methanol lastly to produce 125  µg/ ml solution which was used as derivatizing solution. Preparation of sample solution for UV 10 capsule’s shells were removed and powders from those capsules were mixed and from that weight equivalent to 10 mg Resveratrol and 50 mg Gymnemic acid was weighed accurately and transferred to 10 ml of volumetric flask volume made up with mixture of ethanol: water (1:1). From this solution 1 ml solution was taken diluted with mixture of ethanol: water (1:1).this solution is working sample solution further dilution done by the same mixture. Preparation of standard solution for HPTLC Resveratrol relative standard 20 mg and Gymnemic acid relative standard 100 mg was accurately weighed and transferred to two different 10 ml volumetric flask respectively in which weighed quantity was dissolved in 10 ml ethanol : water (1:1) mixture to produce RES 2000  µg/ ml and GYM 10000  µg/ ml standard stock solution. From these solution 5 ml solution was transferred to 10 ml volumetric flask diluted with ethanol: water (1:1) up to 10 ml to produce RES 1000  µg/ ml and GYM 5000  µg/ ml working standard stock solution. Preparation of sample solution for HPTLC 10 capsule’s shells were removed and powders from those capsules were mixed from that weight equivalent to 20 mg RES and 100 mg Gym was weighed. That much amount of powder was accurately transferred to 10 ml volumetric flask and dissolved in ethanol: water (1:1) mixture. From this solution 5 ml was taken and filtered with 0.45  µm filter sized syringe filter. This solution was then diluted with mixture of ethanol: water (1:1) up to 10 ml solution to produce RES 1000  µg/ ml equivalent and GYM 5000  µg/ ml equivalent. Assay method validation Preparation of calibration curve For UV-visible Spectrophotometric method individual solutions were prepared in methanol from working standard stock solution to produce 5-25  µg/ ml RES and 25- 125  µg/ ml GYM solution. Benzoyl chloride 10  µL was added to each solution. Then these solutions were analyzed in methanol at three different wavelengths at 303 nm, 318.4 nm and 349 nm. Calibration curve here made up was absorbance v/s concentration. For HPTLC method different aliquots of were taken from standard stock solution to make final concentration of RES 1000  µg/ ml and GYM 5000  µg/ ml in the same solution. Then different aliquots were spotted on activated TLC plate. The concentration of RES was varied between (5-25)  µg/ spot while for GYM it was (25-125)  µg/ spot. Then plate was developed in mobile phase and was developed to scan as mention above at 575 nm. Calibration curve here made was peak area v/s concentration of constituents. Accuracy (recovery) For UV-visible spectrophotometer solution of standard RES was added to previously analyzed sample solution at three different levels (80%, 100 % and 120%). Same procedure been followed to have a GYM accuracy by adding standard stock solution at three different levels (80%, 100 % and 120%). Amount of standard RES added was (8, 10 and 12  µg/ ml) to 10  µg/ ml sample solution. Amount of standard GYM added was (40, 50 and 60  µg/ ml) to 50  µg/ ml sample solution. For HPTLC known amount standard solution of RES (8, 10 12  µg/ ml) and GYM (40, 50 60  µg/ ml) added to previously analyzed sample solution having concentration of RES 10  µg/ spot and GYM 50  µg/ spot. Precision The intra-day and inter-day precision of proposed methods were determined by estimating corresponding responses three times on the same day and on three different days for three different concentrations. For UV-Visible spectroscopy RES concentrations were 8, 10 and 12  µg/ ml measured at wavelengths 318.4 nm and 349 nm.GYM concentrations were 45, 50 and 60  µg/ ml measured at wavelengths 303 nm and 349 nm. For HPTLC three different dilutions were made having both RES and GYM in those solutions ranging (RES 9, 10 and 12.5  µg/spot) and GYM (45, 50 and 62.5  µg/ spot). For repeatability in HPTLC, sample solution containing 10  µg/spot RES and 50  µg/ spot GYM was measured in terms of response. LOD LOQ The sensitivity of analytical method was evaluated by determining LOD and LOQ. They are measured by following equations: LOD: 3.3 à ¯Ã‚ Ã‚ ³/ S LOQ: 10 à ¯Ã‚ Ã‚ ³Ãƒ ¯Ã¢â€š ¬Ã‚ ¯Ãƒ ¯Ã¢â€š ¬Ã‚  S Here, à ¯Ã‚ Ã‚ ³ is standard deviation of intercept and S is slope in linearity equation. Specificity For HPTLC spots were scanned for its purity with standard sample and checked whether they give a same response or not. This was done by spectral scanning in WinCats HPTLC. Robustness The robustness of methods was studied by analyzing the same samples of RES and GYM with deliberate change in parameters. The changes in responses were noted. For HPTLC, spots scanned at ( ± 2 nm) and mobile phase ratio change was performed. For UV-Visible method solutions were scanned at ( ± 2 nm). 3. Results and Discussions Simultaneous estimation of RES and GYM was difficult task because they are isolated from herbal source and they have RES: GYM ratio 1:5 in marketed formulations. System suitability parameters System suitability run for HPTLC was performed before each validation run. Five replicate spots were made. Parameters monitored were Rf value and Peak areas of them. (Table 2) Table 2: System suitability Parameters HPTLC Optimization of Method For HPTLC Various experimental conditions such as the mobile phase and the wavelength of detection were optimized to achieve accurate, precise and reproducible results for the estimation of RES and GYM. Good resolution and sharp peaks with minimum tailing of these drugs (Rf RES 0.78, Rf GYM 0.236) was obtained by using mobile phase Chloroform: Methanol : Glacial acetic acid (13: 4 :0.5%) at wavelength of detection 575 nm. Figure 3 : optimized Chromatogram of HPTLC, RES (10  µg/spot) GYM ( 50  µg/spot) Figure 4: Wavelength selection for HPTLC of RES and GYM For UV-Visible Spectrophotometric Form overlain spectra (Figure 5) of methanolic solution of RES and GYM three wavelengths were finalized for analysis 303 nm, 318.4 nm and 349 nm. The method here used for simultaneous estimation is Q ratio method. Here both of constituents are measured at 349 nm isoabsorptive point and 303 nm and 318.4 nm GYM and RES respectively. Figure 5: wavelength selection after derivatization of GYM, BCL (Benzoyl Chloride) and RES Method validation of proposed methods Optimized methods were validated in compliance with ICH guidelines. The results of various parameters are discussed following: Linearity For UV Spectrophotometric method, linear correlation was obtained between absorbance and concentration for RES 5-25  µg/ ml at 318.4 nm 349 nm and GYM 25-125  µg/ ml 303 nm 349nm.( Table 3) For HPTLC method, linear correlations were obtained between peak area and concentration of RES was 5-25  µg/spot and GYM was 25- 125 µg/spot. (Table 4) Accuracy The percentage recovery values of RES and Gym were obtained in the range of 98% to 103 %, and relative standard deviation values for both constituents in two methods were less then 2%, it shows that methods are accurate for both constituents. Values are shown in table 3 and 4. Precision Inter-day and intra-day variation in quantification of RES and GYM showed that RSD values were always less than 2% during the analysis by both methods. These low RSD values show that methods are precise. Values of precision studies for UV spectrometry and HPTLC are in table 3 and 4 respectively. LOD and LOQ For UV-Visible spectrometry method LOD and LOQ for RES was found to be 0.09 µg/ml and 0.28 µg/ml respectively. LOD and LOQ for GYM were 0.63 µg/ml and 1.92 µg/ml respectively. For HPTLC method LOD and LOQ for RES were 0.065  µg/spot and 0.20  µg/ spot respectively. LOD and LOQ for GYM were 1.2  µg/spot and 3.87  µg/spot respectively. Specificity For HPTLC method, a good correlation was obtained between standard and sample spectra of RES and GYM correlation suggests that there in no interference in quantification of RES and GYM. Robustness Robustness of the methods was studied by performing assays of RES and GYM in capsule formulation. The parameters are deliberately altered and changes were recorded. Assay values were calculated in the changed parameters. Methods proved to be robust, because assay values in changed parameters were within limits. Assay of marketed formulation Assay of Resveratrol plus from ZENITH nutrition was performed in both the methods. Results of assay were compared with corresponding amounts claimed on capsule. The assay results are shown in table 3 4. Table 3: UV-Visible method Validation parameters Table 4: HPTLC Validation Parameters Conclusion Developed HPTLC and UV-Visible Spectrophotometric method was found to be simple, accurate, precise, rapid, sensitive and robust for the estimation of RES and GYM in combined dosage form. The validation data and recovery shows that methods are free from inferences of excipients used in formulations. Thus method is useful for both constituents to be estimated by both methods. References x

Leadership Speech :: essays research papers

Many people believe that leadership is simply being the first, biggest or most powerful. Leadership in organizations has a different and more meaningful definition. A leader is someone who sets direction in an effort or task and influences or motivates people to follow that direction. The power point presentation explains leadership is the influence that particular individuals exert on the goal achievement of others in an organizational context. When some think of leadership the idea of the military is taken into account while others use the term to refer to executive management. These are few examples of different types of leaders there are. There are also different roles of leadership such as senior-level executives and middle managers. Motivated leaders who have charisma and high levels of emotional stability will be honest and have integrity in the manner in which they lead. An effective leader must be respected by the members of his or her group in order to perform effectively. Another aspect of leadership includes leadership traits such as being influential and inspirational. There also different contexts of leadership, e.g, leading oneself, leading other individuals, leading groups, leading organizations. Some traits that are often associated with being an effective leader include a measure of intelligence, high energy, self confidence, dominance, and a need for achievement. An effective, charismatic leader must lead by example. That leader must be able to know what is going on, the job or task that is being accomplished, and be able to lead the group into performing the task at hand successfully. There are many different types of theories on leadership. There is Fiedler’s contingency theory, situational theories of leadership and House’s path-goal theory. These theories are used to make an individual or manager a more effective leader. They can be used as a guide for individuals and help them achieve whatever goal is set out by their organization or group. Fiedler’s Theory is stated in the power point presentation as the association between leadership orientation and group effectiveness is contingent on how favorable the situation is for exerting influence. If there is some catastrophe which will befall a group or set of individuals if a task is not complete, then that group will be more effective as they are motivated to complete that task to avert that particular catastrophe. The Situational Theories of leadership explain how leadership style must be tailored to the demands of the task and the qualities of subordinates.

Height and Weight Data on High School Children Essay -- Data Handling

Missing Some Graphs Handling Data Coursework Introduction This is based on fictional data on a school called Mayfield high school. I will be comparing two variables I have chosen to compare the relationship between the height and weight of the pupils in the school. It will be involving the following year groups seven, eight and nine. The data that I have been given to me is a secondary source, which was provided to me by teacher which was from the internet. The data has provided me with each pupils name, age, year group, height, hair and eye color, and the distance from home to school, traveling method, number of brothers and sisters and KS2 results. The aim of this investigation is to find out a relationship between two variables, the two variables which I have chose to investigate are height and weight. Hypotheses To test my first hypothesis i.e. as pupils get older the boys and girls get heavier and taller. I will carry out a stratified sample of 60 boys and girls. The reason why I will do a sample is because it will show the different proportions of people in each year group and gender. Therefore my data will be representative of Mayfield High School. Once I have collected the data I will then organize the heights and weights of the girls and boys in a grouped frequency table. I will then use this table to find the mean, mode, median of the results of the heights and weights of these males and females. I will then construct a cumulative frequency graph to find and locate the median, lower quartile and upper quartile. This will then be used to draw a box plot for the heights and weights of male and females. This data will be used to help me to conclude my first hypothesis. To test hypothesis two i.e. girls in y... ... that overall my hypothesis is correct. This is shown in the graphs of the data showing the boys and girls in year eight, nine and eleven. However in the graphs showing year seven and ten proves that my hypothesis is wrong. Also my last graph shows an overall outlook of the whole population I had sampled and it shows a very positive correlation of the taller you are the heavier you are. To conclude my coursework I have learnt that all of my hypotheses are correct. My first hypothesis was the older you are the heavier you weigh. My second hypothesis was the girls in year seven are taller and heavier then boys in year seven. My last hypothesis is the taller you are the heavier you are. From investigating these I have learnt that the older you are the heavier you are, year seven girls are heavier and taller then boys and the taller you are the heavier you are.

Rubin Hurricane Carter: Guilty Until Proven Innocent Essay -- Court Mo

Rubin Hurricane Carter: Guilty Until Proven Innocent '"I don't belong here and I am not going to play their game.' 'If I were to cooperate in all these things, it would be as if I were saying, 'I'm a guilty man, and I am not a guilty man"' (New Jersey). The case of Rubin (Hurricane) Carter has been a heated issue for the last 34 years. In the last year a new movie, The Hurricane, starring Denzel Washington has once again brought this case to the foreground of discussion. The question argued has been is Rubin Carter innocent or guilty of the murders he allegedly committed on June 17, 1966 in the Lafayette Grill in Paterson, New Jersey. The proof is undeniable that Carter is innocent. He had an unfair trial where the police played a negative part, the prosecution suppressed information, and the court also worked against Carter. Although Rubin Carter is innocent of the crimes committed that fateful night in Paterson does not mean he was an angel. The biggest threat to Rubin's defense in this case was himself. Rubin Carter was born May 6, 1937 in Delawana, New Jersey. He grew up in the nearby town of Paterson (J.K.B. 7). Rubin was a strong-willed boy who learned to stand up to everyone as a child. James S. Hirsch, the author of Hurricane: The Miraculous Journey of Rubin Carter wrote, "the men in his family are not intimidated by threats" (60). In chapter 5 of his book, Hirsch explains how Rubin Carter learned to stand up against authority. Born with a stutter, he would fight anyone who dared to make fun of his speech-impediment. Carter once beat up his younger sister Rosalie's teacher when he saw him chasing her. He was expelled from school and beaten by his father. It was displays like this that caused Carter's father fear... ...'Deal' for Freedom in Murder Case." New York Times [New York] 4, Dec. 1975: 45:2. "Carter Lawyers Focus of Dispute." New York Times [New York] 29, Jan. 1975: 39:1. Hirsch, James S. Hurricane: The Miraculous Journey of Rubin Carter. Boston and New York: Houghton Mifflin Co., 2000. J.K.B. "Carter, Rubin." Current Biography May 2000: 6-14. "Lawyers for Carter Say Judge Erred on Appeal." New York Times [New York] 28, Jan. 1975: 54:7. Massaquoi, Hans J. "Hurricane Carter: I Was Framed For Murder!" Ebony Dec. 1974: 30: 174-6+. "New Jersey Journal." New York Times [New York] 5, Feb. 1984: XI 3:1. "Police Record Backs Carter's Story." New York Times [New York] 23, Oct. 1975: 83:4. "Reversal is Won By Rubin Carter In Murder Case." New York Times [New York] 8, Nov. 1985: "Same Judge Gets Carter's Appeal." New York Times [New York] 31, Jan. 1975: 37:8.

Employment Law and Compliance Plan Essay

Atwood and Allen Consulting Bradley Stonefield Limousine Service Recruitment and Selection Strategies Recommendations Atwood and Allen Consulting Bradley Stonefield Limousine Service Recruitment and Selection Strategies Recommendations The Bradley Stonefield Limousine Service Company has been established to providetransportation to public. The first step is recruitment and selection of prospective new employees that will organize and man the business. The Human Resource Department must explore resources to find right candidates. Recruitment and selection team must addressing the job responsibilities and scope of work of each new position. The staffing process is normally divided into recruitment phase and the selection phase. Recruitment is the searching and attracting of job seekers and the selection is the part job seekers are chosen to get the offer to fill the vacant position. The Bradley Stonefield Limousine Service Company first step is planning human resource. Develop policies, system, procedure and goal setting and method of performance appraisal. Bradley Stonefield Limousine Service Company interviews should have standard company operating procedures and recruitment policies that take care of the recruitment process. These policy, systems, procedures were prepared and approved by Bradley Stonefield. It will be reviewed yearly to ensure compliance to new laws and new business environment or requirement. The Human Resource will periodically review and assess the current and futurehuman resource requirements.The Bradley Stonefield Limousine Service Company formal recruitment process begins when Bradley Stonefield decide or announce the start of the operation of his business. Look more:Â  google recruiting process essay Bradley Stonefield makes that decision because he will have to finance the whole endeavor or business. HR staff initiates the request and documentation. The recruitment request will be evaluated by Bradley Stonefield. He will take several factors in consideration in making his evaluation together with his HR staff. Among the factors he will have to consider are postings, the requirements, the financial constraint, and so forth. Once he approved the recruitment process it will be a go to implement. The job description and person specification is to be prepared by HR staff in consultationwith Bradley Stonefield. These will contain the details of duties and responsibilities to be performed by the selected individual. The Bradley Stonefield Limousine Service Company will advertise the job opening in major media of mass circulation and community service bulletins. The Bradley Stonefield Limousine Service Company will shortlist candidates for interview. If the applicant meets all the essential criteria defined in the job description the next process is the interview phase. The Bradley Stonefield Limousine Service Company will conduct a two part interview sessions two sessions for drivers. First is the personality, background, skillset interview, which is the preliminary interview. This also includes the authentication of driver’s license and drug test. Before the preliminary interview start, the candidates are required to fill application form. It will contain information such as the applicant’s personal biodata, job experiences, and reason for leaving previous employment. Successful candidates in the first interview will be required to come back for the second interview. Bradley Stonefield and HR staff will make decision who to hire. All candidates will be asked the same questions and will be presented the same situational scenario or event. All questions will be job related to determine the suitability of the applicant to the position being filled out, whether that is a limousine driver or customer service receptionist The Bradley Stonefield Limousine Service Company policies will serve as a guideline and administer the company employment process. The hiring procedure ensures that the most qualified candidates is selected. Bradley Stonefield uses a rigorous recruitment and selection process, which complies to the equal opportunity policy. The Bradley Stonefield Limousine Service Company recruitment strategies in vital in finding top talent. The recruitment strategies that are implemented by Bradley Stonefield Limousine Service Company are as follows: 1.) Recruiting through Internet. One of the advantages of using the internet is that it is easily accessible by anyone. 2.) Referrals. Recommended by friends, colleagues, acquaintances. 3.) Advertisements. Advertise job vacancies in the of newspapers great circulation. Again, it is extremely important that the selection process be evaluated regularly to verifyand confirm that the right applicants or employees have been selected or chosen. If Bradley Stonefield Limousine Service Company if the company has significant turnover in a given position, the process of recruitment and selection must be changed. People are a major component of any business, and the management of people (or human resource management, HRM) is a major part of every manager’s job. It is also the specialized responsibility of the HR department. HRM involves five major areas: staffing, retention, development, adjustment, and managing change. Together they compose the HRM system, for they describe a network of interrelated components. The HRM function is responsible for maximizing productivity, quality of work life, and profits through better management of people. Hiring manager, like Bradley Stonefield, must focus on recruiting activities aimed at attracting the right candidates for the job. Based on the needs and forecasts for future needs, Bradley Stonefield will need to direct his efforts toward the best option for recruiting the right candidates. For instance, focusing on traditional newspaper advertisements is appropriate for driver positions with the Bradley Stonefield Limousine Service Company. Selecting the right candidate requires identifying the specific skills, knowledge and qualities you seek and desire in a worker. This can pertain to the necessary skills and knowledge for the position itself, such as a specific degree or certification, and the desired personal qualities, such as a preference to hire employees with good moral and ethical standards. Other important parts of the selection process include conducting any necessary aptitude tests and conducting a thorough background check to ensure the employee meets the basic qualifications of both the position and the company.

E-Business and E-Commerce

display E-Business is important in future perspectives considering that the make sense of trade conducted electronically produce gravid extraordinarily since the spread of the earnings. E-bussiness engrosss the internet and an disparate(prenominal) net profits as hale as a variety of Internet technologies to aliment e-commerce and clientele processes. It includes e-commerce, which is the buying and selling of products or prevail over the Internet. The Internet and related technologies have changed the way businesses ar operated and people work. I.E-BUSINESS A. What is it m either an(prenominal) businesses today are using Internet technologies to conduct business processes over the Internet. E-business prat be defined as the use of the Internet and other networks, as well as Internet technologies to work and despatch business processes, electronic commerce and attempt collaboration within a association and with its customers, suppliers and business partners. Genera lly, any on canal exchange of information, money, resources and run is a part of e-business. B. E-business infrastructureE-business infrastructure do up of a variety of components. It includes hardware, softwares, support run, human capital and telecommunication networks. Examples of hardware are computers, servers and routers. Human capital, such(prenominal) as information system specialists and programmers, is important to operate e-business processes. In addition, many companies use networks such as intranet that is a undercover network inside a company for managers and employees, and extranet, which cerebrate a company with its customers, suppliers and business partners impertinent the company.Other companies use a virtual cliquish network (VPN) which provides a private line through the internet. It uses the public Internet backbone as a channel for private data communication (320). Thus, a VPN allows conflicting offices, business partners and customers to use the Int ernet, rather than pricey private lines, to reach company networks by using tunneling software. This software encrypts data and because sends the data to their destination. II. E-COMMERCE A. What is itE-commerce is the buying, selling, marketing and servicing of products, services and information over the Internet and other networks. Many businesses use the Internet, intranet and extranet to support the commercial-grade processes including advertising, sales, customer support and Internet security. roughly advertisements on the Web are in the form of sending e-mails and banner ads, which is in shape of a long level rectangle on the top of the Web page (310). These advertisements could attract a huge second of visitors to the advertised Web site.E-commerce website must armed service customers to welcome and serve them personally and efficiently in order to increase customer loyalty. B. E-commerce advantages and disadvantages E commerce has several advantages. For sellers, e- commerce is an in force(p) way to reduce woos and set forth their markets. They cut additional labor cost and they do not need to score and distribute mail order catalogs. In addition, e -commerce allows customers to compare prices at different websites.Then, they make leverages at their homes at any time. E-commerce websites offer variety of products for example electronic books, music files and computer softwares. However, e-commerce has just about disadvantages. Consumers are not willing to buy some products over the Internet because of security and gauge concerns. Online furniture businesses, for example, have failed because customers want to establish the comfort of an expensive item such as sofa before they purchase it (11).