Bridge expansion joints – performance and materials 1.1 Introduction Expansion joints are used in bridges to allow movements like expansion and contraction between the bridge deck spans and abutments. These movements are caused due to temperature, soil settlements, vehicle acceleration and other reasons (Klaiber, et al., 1987 and Dagher, et al., 1993 as cited in Thippeswamy, 2002). Expansion joints are subjected to severe loading due to the direct impact of the wheels. They are a very important component of a bridge structure and if carefully designed, properly installed and reasonably maintained will give a trouble free performance for many years. Though joints are made of various materials like rubber, silicone and polymer they deteriorate since they are constantly exposed to impact, vibration of traffic and natural elements like water, dust, ultra violet rays and ozone (Chang Lee 2002). The durability of expansion joints is a major concern to bridge owners. The maintenance cost of joints is relatively high than the initial cost .This led to the design of jointless bridges. Jointless bridges do not develop stress due to corrosion of joints, accumulation of debris and differential elevation of joints (Thippeswamy, 2002). The behaviour of the jointless bridges not known and the designs being complicated are not implemented in spite of their advantages. This literature review deals with: characteristics of a good expansion joint that must be noted while design a joint, defects observed in expansion joints, survey studies conducted on existing joints to study their behaviour and some manufactures of bridge expansion joints in the industry. Studies on improving the performance of expansion joints is conducted, research on reducing the cost of maintenance of the joints should be conducted. 1.2 Characteristics of a good expansion joint A bridge expansion joint for proper functioning must have the ability to: accommodate movements in vertical and horizontal direction; withstand applied loads; resist skid and corrosion; operate silently with less maintenance (Lee, 1994). Price (1984) suggests that the performance of a joint is influenced by structural movements of the joint in horizontal and vertical direction, traffic loading, materials used, condition of the substrate, weather and temperature during joint installation, workmanship and performance of bearings. 1.3 Commonly observed joint defects Guzaltan (1993) as cited in (Chang Lee 2002) studied some commonly observed defects in expansion joints. They include damaged seals, accumulation of debris in the joint components, rusting of metal plates and nuts, cracking of concrete, corrosion of steel reinforcement, water leakage, improper joint alignment and joint vibration during vehicle passage. Fincher (1983) as cited in (Chang Lee 2002) presents the results of a survey conducted by Federal Highway Administration during a five year evaluation period which demonstrated that 60% of the expansion joints examined leaked. Additionally, Wallbank (1989) as cited in (Lee, 1994) explains that in a survey conducted on two hundred bridges by The London Department of Transport, the deterioration of the expansion joints was caused due to leaking and faulty drainage details. Chang and Lee (2002) conducted a study to observe the performance of joints in Indiana and found that some joints failed due to cracks in the seal and suggested testing it before installation. Fault tree modelling was used for qualitative explanation of bridge element interaction but could be used only for catastrophic failures (Attoh- Okine Bowers 2006). These models are not applicable to bridges since they fail over an extended period of time. Fault tree models were also prepared by LeBeau and Wadia-Fascetti (2000) and Sianipar and Adams (1997) as cited in (Attoh- Okine Bowers 2006). A new deterioration modelling based on belief networks that effectively capture and illustrate the hierarchical, interaction and uncertainty factors present in bridge deterioration was developed by Attoh- Okine and Bowers (2006). Belief networks are also called Bayesian belief networks and are based on Bayes theory. The belief network approach is more appropriate than fault tree analysis since it can be used to investigate the components of a bridge including deck material, girders, bearings and abutments have a great influence on deterioration. 1.4 Studies conducted on the performance of existing expansion joints Chang and Lee (2002) conducted a study to observe the performance of the different joints used in the highway bridges in Indiana. Five popularly used joints were: compression seal (B.S), strip seal (S.S), integral abutment (I.A), poured silicone (X.J.S) and polymer modified asphalt (P.M.A). The data was obtained from questionnaire survey, analysis of Indiana Department of Transportation (INDOT) roadway management data and expert interviews. Questionnaire survey was conducted by giving questionnaires to the state bridge inspectors and engineers around Indiana. The problems with joints were encountered and possible improvements were suggested. The analysis of historical data using logistic regression approach found that S.S joint had the best performance. The expert interviews consider I.A joint to offer good results and suggest improvement of B.S and S.S joints. An inspection campaign was conducted on 150 expansion joints of 71 road bridges in Brisa, Portugal where the maintenance cost reached a peak of 25% (Lima Brito 2009). The joints installed within the traffic lane of the bridge were considered. The expansion joints were characterised based on their type, and age of the bridge. It was recorded that the joints used more frequently included reinforced elastomeric cushion joints, elastomeric flexible strips, and asphaltic plug joints. The data obtained from the inspection campaign was statistically analysed. The results showed that joints that were replaced mostly frequently were elastomeric joints and that different joints have specific maintenance needs. The transition strip and the anchorage cavities of the expansion joint are the parts that require more maintenance. It was also observed that the errors during installation and lack of maintenance caused pathology of the joint. The results of campaign conducted show that there was a lot of improvement in the commercial expansion joints and suggests investigation on the new or improved systems and materials. It also suggested that simple systems with fewer components are more reliable and require less maintenance. Asphalt bridge expansion joints when used in cold countries cracked within the first two years. To improve the performance the commercial MEIJIA asphalt binder was modified with polymers: thermoplastic rubber and rubber (Yu, et al., 2009). The polymers were used in various combinations, and their performance at low temperatures is evaluated by conducting tests including: ductility, penetration, indirect tension and bending tests. The data from ductility and penetration tests performed on binders indicated that the strength and deformation capacity at low temperatures improved. Four expansion joints made with the modified asphalt mixtures were installed on two bridges in a cold region and found that the joints showed good performance. 1.5 Assessment of expansion joint performance using monitored data A study was conducted by to develop a procedure for verification of the design and evaluating the condition of expansion joint by monitoring joint displacement and bridge temperature on a long term (Ni, et al., 2002). This method was applied to Ting Kau, cable stayed bridge in Hong Kong. The service life and replacement of joint depends on the cumulative displacement. An accurate prediction of the cumulative displacement will provide the time interval for joint inspection or joint replacement. Monitoring the thermal movements at the expansion joints and comparing them with the design values provide verification on design. The whole system had more than 230 sensors like anemometers, accelerometers, displacements transducters to measure displacements located at the ends of the deck, temperature sensors, strain gauges, weight in motion sensors and global positioning system. A good correlation between the movement of the expansion joints and effective temperature was observed. The daily average cumulative displacements of the expansion joints in the bridge are much less than design values. Additionally monitoring systems had been implemented on many bridges in different countries by (Andersen Pedersen 1994; Cheung et al. 1997; Barrish et al. 2000; Sumitro et al. 2001; Mufti 2002; Koh et al. 2003; Wong 2004) as cited in (Ni et al. 2002). 1.6 Effect of SSI and ground motion spatial variation Chouw and Hao (2008(a)) studied the effects of soil-structure interaction (SSI) and ground motion spatial variation effect on bridge pounding responses for bridges with a traditional expansion joint between adjacent girders. The study was conducted on two adjacent bridge frames. It was confirmed that structures that are built on stiff soils may experience larger pounding forces than those on soft soils. It was also examined that decrease of ground motion correlation caused larger pounding responses. Numerical simulation was conducted by nonlinear dynamic response analysis and investigated pounding mitigation and prevention of unseating in the highway bridges due to seismic forces (Raheem, 2009). It was observed that seismic pounding generates significantly higher magnitude and short duration acceleration pulses than typically assumed design magnitude. This results in severe impact forces that damage structural members like the deck or pier. Additionally the effects of SSI and bridge pounding response for bridges with modular expansion joint system (MEJS) were observed (Chouw Hao 2008(b)). It was concluded that the girders with a large gap of a MEJS caused stronger impact forces. It was found that significance of nonuniform ground motions depends on the properties of the ground motions, subsoil and the structures. 1.7 Types of Expansion Joints 1.7.1 Selection of joint type The type of joint is selected depending on the movement expected for serviceability limit state. More than one type of joint may be suitable for a particular range of movement. The movement range that should not be exceeded for each expansion joint is given in Table 1. Table 1. Selection of joint type (Department of Transport, 1989) Joint Type Total acceptable longitudinal movement Maximum acceptable vertical movement (mm) Maximum (mm) Minimum(mm) Buried Joint under continuous surfacing 5 20 1.3 Asphaltic plug joint 5 40 3 Nosing joint with poured sealant 5 12 3 Nosing with preformed compression seal 5 40 3 Reinforced Elastomeric 5 * 3 Elastomeric in metal runners 5 * 3 Cantilever comb or tooth joint 25 * 3 * Maximum value varies according to manufacturer or joint type 1.7.2 Modular bridge expansion joint Modular expansion joint is used when the joint movement exceeds 100mm.The modular expansion joint has many advantages including: water-tightness, corrosion protection, great potential as they increase the life of concrete and steel bridges (Crocetti Edlund 2003), greater movements in translation and rotation. It can accommodate the three dimensional movements without generating additional stresses or strains in the load-bearing members or in adjacent bridge or abutment structures. 1.7.2.1 Noise generation in a modular expansion joint The traffic generates more noise on bridges than on roads, as sound is produced on the top and bottom of the deck. The noise generated from a modular expansion joint under vehicle passage is louder than those of ordinary expansion joints (Ravshanovich, et al., 2007). The mechanism of noise generation for a modular bridge expansion joint which causes noise pollution was studied by conducting tests on a full scale model of a joint. A series of car-running experiments were conducted on the joint and studied its noise and vibration characteristics. A modal analysis of the joint is performed using finite element modelling. It was observed that the frequency of the noise generated above the joint varies from 500 to 800Hz due to sudden change in air pressure within the gap formed by rubber sealing with the middle beams. The frequency is less than 200Hz below the joint caused by the sound radiation due to the bending vibration modes of the middle beams being excited by an impact force from the car wheels. Likewise a numerical investigation was conducted on a modular expansion joint of an expressway bridge to understand the generation and radiation mechanism (Ghimire, et al., 2009). The numerical analysis was conducted using finite element method. 1.7.2.2 Performance of Modular expansion joint Modular joints have the ability to cope with large thermal expansion and contraction of large bridges (Chouw Hao 2008(b)). They are capable of preventing girder pounding during strong earthquakes. A complex joint was modelled to study the dynamic response of a modular bridge expansion joint (Crocetti and Edmund, 2003). The vertical loads perpendicular to the roadway plane were considered. Horizontal loads were eliminated since the excitation mechanism was sophisticated and the behaviour of the joint in the horizontal direction was stochastic in character. A single fatigue test was performed. Data from the field tests including measurement of wheel load distribution factors, horizontal and vertical wheel loads, determination of damping and natural frequencies were obtained from Lehigh University, Bethlehem, Pennsylvania. The result of the fatigue test conducted agreed with the S-N curve plotted for welded connection between the support bar and the centre beam suggested by Dexter, et al. (1997) cited in (Crocetti Edmund 2003). Additionally an experimental investigation was performed to study the fatigue performance of a welded multiple support bar modular bridge expansion joint (Chaallal, 2006). The welded multiple support bar modular bridge expansion joint was used in the rehabilitation of Jacques Cartier Bridge in Montreal. The vertical and horizontal loads were considered unlike (Crocetti Edmund 2003) which is more practical since the expansion joints are subjected to both vertical and horizontal loads. Experimental tests were conducted on three subassemblies of the modular joint for various loads and S-N curve was plotted. 1.8 Manufacturers of Expansion joints 1.8.1 The Bridge Joint Association Bridge Joint Association (BJA) prepares standards and current practice sheets. It comprises of manufacturers and installers of bridge expansion joints which include: ASL CONTRACTS LTD, FREYSSINET LTD, GRACE CONSTRUCTION PRODUCTS LTD, Highways Maintenance Specialists LTD and MAURER LTD (Bridge Joint Association, 2009). 1.8.2 Watson Bowman Acme Corporation Watson Bowman Acme Corporation (WBA) found in 1950 isa recognized innovator in the development and manufacture of expansion joint controlsystems. Some of the joints manufactured by WBA include: Wabo®Crete SiliconeSeal This is a high performance expansion joint system that utiÂlizes a two-part sealant between elastomeric concrete headers made of Wabo®Crete II capable of absorbing impact loads. The headers are coupled with Wabo®SiliconeSeal make it an ideal expansion joint system that is adopted in the industry for new construction or repair of existing joints. Wabo®Crete II elastomeric concrete is widely used in header applications for bridges and parking structures. Polyurethane is used in the header material to minimize edge spalling associated with high impact loads while achieving superior bonding capabilities. The Wabo®SiliconeSeal is a cold applied self levelling sealant requires no priming which simplifies accelerÂates the installation process. Wabo®Crete SiliconeSeal system is licensed under US Patent No 5.190.395. This joint is adopted for applications with a maximum movement range of +100% / -50% of the joint gap (Watson Bowman Acme, 2007). Wabo®Crete FlexFoam This is an armorless expansion joint system that is designed with closed-cell foam joint seal installed with epoxy adhesive between an impact absorbing elastomeric concrete header. The high impact absorbing, ambient cured and self-levelling properties of the Wabo®Crete II joint header allows for the joint system to monoÂlithically bond to the deck creating a watertight system. Using an elastomeric concrete joint header achieving superior bonding caÂpabilities and minimizing edge spalling (Watson Bowman Acme, 2007). Wabo®Expandex This is a flexible asphaltic plug joint system designed to accommodate minimum structure movement while providing a smooth transition between the apÂproach pavement and the bridge deck. Wabo®Expandex is used typically at abutÂments or asphalt overlays due to its unique asphalt compatibility. The system combines the use of a traffic bearing plate with special aggregate reinforced modified elastomeric material (Watson Bowman Acme, 2007). Jeene® This joint system comprises of a neoprene profile, which is air-pressurized and bonded in place with a specially formulated epoxy adÂhesive. With properly installation, the Jeene® joint system will not tear away, protrude out of, or slip from its original position on exposure to repeated mechanical or thermal movements. Complete adhesion of the epoxy to the profile and joint wall is achieved due to the air inflation during installation. Jeene® is the most durable, versatile, cost-effective and watertight expansion joint (Watson Bowman Acme, 2007). Wabo®HSeal This is a pre-compressed elastomeric coated expansion joint system deÂsigned to provide a permanent weather tight seal. The system is sealed in place with an epoxy, which allows it to accommodate horizontal, vertical, and skew expansion joint movements. Wabo®HSeal consists of a micro-cell, stable to UV, polyurethane foam impregnated with a hydrophobic polymer and topped with a traffic grade elastomeric coating. The imÂpregnated foam provides a valuable secondary water tight seal in case the primary elastomeric coating is damaged. This system is supplied in pre-compressed sticks for easy installation (Watson Bowman Acme, 2007). Wabo®Flex This is a molded rubber cushion expansion joint which is designed to accommodate structure movements from 2 inches up to 13 inches. In Wabo®Flex system the molded rubber cushions are steel reinforced and imbedded with corrosion-resistant aluminium wear plates. Tongue and grooves at the end of each rubber cushÂion ensure a watertight connection and prevent uplift or separation (Watson Bowman Acme, 2007). Wabo®TransFlex This is an original reinforced elastomeric molded rubber expansion joint system. All sections feature tongue and groove fittings for tight end-to-end mating across decks and at curbs and are steel reinforced. It can be installed in new decks, or in older structures on rehabilitation projects. These joint systems readily adapt to skew angles. Wabo®TransFlex system will accommodate anticipated thermal movements reject debris and create a level, smooth-riding, wear-resistant surface if properly installed (Watson Bowman Acme, 2007). Wabo®Seismic WeatherSeal This is a pre-compressed elastomeric coated exÂpansion joint system that works under its own constant internal pressure to provide a weather resistant seal. The system contains an open-cell foam seal imÂpregnated with a hydrophobic polymer sealing compound. Wabo®Seismic WeatherSeal can be used on applications which cause simple thermal movements or on applications where seismic movement is anticipated. The Wabo®Seismic WeatherSeal system is recommended for use on all inÂterior and exterior wall, ceiling and soffit expansion joint applications (Watson Bowman Acme, 2007). The joint systems manufactured by Watson Bowman Acme Corporation are compared as shown in Table 2, with respect to their features and their recommended area of implementation. Table 2: Comparison between the various joints manufactured by WBA. Joint Features Recommended for Wabo®Crete SiliconeSeal Watertight system, rapid installation, Cold applied, Expansion joint applications with a maximum movement range of +100% / -50% of the joint gap Horizontal expansion joint applications on bridges and highways. Wabo®Crete FlexFoam Accommodates movement cycle through compression and tension, Minimizes dirt or debris accumulation Horizontal expansion joint applications on bridges and interstate highways. Wabo®Expandex. Provides smooth riding surface, can be milled or planed during resurfacing operations, joint openings with movements up to +/- 0.75 at time of installation Sealing joints on secondary highway bridge structures. Joint Features Recommended for Jeene® . Accommodates forces associated with multi-directional movements, resists hydrostatic pressure, Accommodates thermal movement Sealing joints on bridges roadways and tunnels. Wabo®HSeal Can accommodate horizontal, vertical and skew expansion joint movements, easy installation Sealing joints on bridges, sound wall barriers Wabo®Flex maximum friction, prevents debris accumulation, reduces deflection under traffic loadÂing, maximum movement of 13 inches Bridge decks and ramps, Low height joint sealing restrictions Wabo®TransFlex Watertight connection, prevent uplift or separation maximum movement of 13 inches Low height joint sealing restrictions bridges, decks and ramps Wabo®Seismic WeatherSeal seismic movement capability, weather resistant, self-expanding non-laminated construction, accommodates movement up to +/- 50% Stadiums, parking garages, Replacing failed joints 1.8.3 Universal Sealants Limited Universal Sealants limited (USL) focuses on construction of bridges, tunnels, rail and other major structures. It manufactures supplies and installs specialist construction products including: bridge expansion joints; membranes for bridge deck waterproofing; protective coatings; concrete repair and car park refurbishment work. Some expansion joints offered by USL include: Uniflex expansion joints This system uses a butyl rubber membrane, bonded to the concrete and asphalt surfaces with Uniflex epoxy adhesive to provide an efficient and permanent joint that is easily installed. The system accommodates a variety of conditions from those experienced on an asphalt-covered traffic-free roof, to bridge decks with sheet membrane, spray on coating or asphalt waterproofing, also it can be used with two layer mastic asphalt or brick paving systems. The Uniflex system is chemically inert and completely impervious to water and water vapour. In buried joints the membrane is completely protected by the wearing surface. Uniflex membrane will not deteriorate during its service and the combination of a simple design and proven components makes the system naturally long-lasting and well up to the requirements of modern building and civil engineering practice (Universal Sealants UK Ltd, 2009). Febajoint This joint is fully registered with the Highways Agency, Scottish Executive and Welsh Assembley (BD 33/94: Joint Type 2) suitable for all class roads and motorways. The joint is nominally 500mm wide and not less than 100mm deep which will provide optimum movement capacity of +/- 20mm. The materials are applied hot and in a fluid condition, with temperatures up to 180°C. Careful considerations should be made by the engineer before using this joint. Binder compounds use thermoplastic materials which contain polymer modified bitumen, mineral fillers and chemical additives (Universal Sealants UK Ltd, 2009). FEBA HM expansion joints The system is fully registered with the UK Highways Agency for type 2 application. It is a high modulus flexible, waterproof asphaltic plug joint. The main feature of this system includes a resistance to wheel tracking. This joint is suitable for a maximum horizontal design movement of ±20mm. The FEBA HM system should be considered in places of high traffic volumes, constant standing traffic or heavy loading. The materials are applied hot and in fluid condition, with temperatures up to 180°C. Binder compounds are classified as thermoplastic materials and contain polymer modified bitumen, mineral fillers and chemical additives (Universal Sealants UK Ltd, 2009). Nosing Joint (NJ) system This joint system is an ideal for maintenance situations and has been developed to provide a whole life economic solution for applications where asphalt plug joints are unsuitable and is registered with the UK Highways Agency, The Scottish Executive and Welsh Assembly. A surface mounted nosing joint with an elastomeric insert bonded to the rapid curing elastomeric compound known as Britflex® Resin Mortar (Universal Sealants UK Ltd, 2009). The Transflex, Waboflex and Euroflex These joints are registered with the UK Highways Agency, the Scottish Executive and the Welsh Assembly for use on highway bridge decks (BD 33/94: Joint Type 5). These joints are reinforced elastomeric comprising of steel angles and a steel bridging plate system encased in a flexible elastomer. The movements that can be accommodated vary from 38mm to 330mm in structures including: All types of highway structures, car park decks, footbridges and podium decks (Universal Sealants UK Ltd, 2009). The Britflex® BEJ Expansion Joint These joints are registered with the UK Highways Agency, Scottish Executive and Welsh Assembley for use on bridge decks on all classes of roads and motorways. (Department of Transport BD33/94: Joint Type 6). This system is ideal for maintenance projects where there is a need to replace failed systems. The major benefit of this system is its speed of assembly on-site (Universal Sealants UK Ltd, 2009). Londitudinal Joint (LJ) system This system has been developed to provide an effective method of sealing longitudinal expansion gaps and soffits. This joint accommodates both longitudinal and vertical movement and also provides a substantially watertight seal. The LJ joint system can be used as a waterproof cover joint or as a drainage channel under joint with the facility to install drainage outlets into the system (Universal Sealants UK Ltd, 2009). Table 3: Comparison between the various joints manufactured by USL. Joint Type Features Uniflex Expansion Joints Type 1-Buried joint under continuous surfacing Impervious to water and water vapour, long-lasting, simple design Joint Type Features Febajoints Type 2-Asphaltic Plug joint Provides optimum movement capacity of +/- 20mm, joint for use on highway bridges FEBA HM Expansion Joints Type 2-High Modulus Asphaltic Plug joint Can accommodate impact loads, maximum horizontal design movement of ±20mm Nosing Joint system Type 4-Nosing with preformed compression seal Rapid Installation, No drilling of deck, can only be used in the situation where the gap at carriageway level does not exceed 65mm. Transflex, Waboflex and Euroflex Expansion Joints Type 5-Reinforced Elastomeric Accommodating movement from 38mm to 330mm. used for car park decks, footbridges, podium deck. Britflex® BEJ Expansion Joints Type 6-Elastomeric in metal runners Rapid on site assembly, less future maintenance costs, easy to install Longitudinal Joints Longitudinal Joint System can accommodate both longitudinal and vertical movement, rapid installation, low maintenance, cost effective , watertight seal 1.8.4 Stirling Lloyd Stirling Lloyd specialise in the development, manufacture and application of high-performance waterproofing and structural protection membranes and systems. They deal with road and rail bridge decks and tunnels, to commercial building developments, car parks and highway maintenance solutions. Some of the joints manufactured by Stirling Lloyd include: Sentinel® B This joint consists of a PVC flashing strip designed for various movement ranges. The flashing is bonded across the expansion gap and incorporated into the Eliminator® water proofing system to form a continous waterproofing detail below
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12/25/2019 0 Comments Reverse phase High Pressure Liquid Chromatography for measuring hydrolysis of ester Essay Example for Free Reverse phase High Pressure Liquid Chromatography for measuring hydrolysis of ester Essay Reverse-Phase High performance chromatography consists of any method of chromatography that utilizes a non-polar phase. In the early part of 1970s, non-modofied alumina or silica which has a greater attraction for polar elements and hydrophilic surface chemistry was used for majority of the liquid chromatography. Because of this, this method was said to be normalâ€. The elution order was however reversed with the introduction of a covalently bonded alkyl chain which reinforces the surface. In this method, the first to be eluted are the polar compounds while there is retention of the non-polar compounds hence the procedure is termed reversed phase Method validation It’s important to validate all various HPLC methods. Evaluation of suitability may not be necessary when methods from pharmacopoeia’s are utilizes given that the analyses are carried out with respect to the technique’s intended use. However, in situation where drug composition is being modified, a reevaluation of suitability of the HPLC method to its new intended use is necessary (Nagels etal, 2002). The variables tested in the validation process as stated by FDA, ICH and USP as well as other health bodies include: Accuracy, linearity, limit of quantitation, limit of detection specificity relativity, reproducibility precision which includes repeatability, intermediate precision as well as ruggedness/reproducibility (Amersham, 1999). Role of rp-HPLC method for the measuring hydrolysis of ester Reverse phase high pressure liquid chromatography can be used in separation quantitation of free fatty acids as well as its methyl esters obtained from tissue phosphopids of mineral. In this method, mixtures of water acetonitrile are utilized for elution of esters. For free acids to separate, aqueous phosphoric acid substitute for water. Quantification detection of unsaturated compounds are done by absorption at 192nm . After methyl esters have been prefractionated based on its unsaturation by argentation TLC, there is total rapid separation by elution with CH3CN. Reverse phase HPLC can both be applied as preparative analytic method as well as in biochemical separation and purification. Precision In rp-HPLC, precision is assessed by injection of several standards followed by measurement of the variability of the results. Three subcategories are obtained from the measured standard deviation . To assess repeatability, the operator executes the analysis in a laboratory over a short period of time. Then, the relative standard deviation is calculated from 5 or 6 determinates of two dissimilar matrices at 1 or 2 different concentrations. The ICH describes intermediate precision as long term variability this is estimated by comparison of several results of a single laboratory over several weeks. Variations of results gotten by different instruments, different batches of column and from operators with materials from dissimilar supplies are reflected in intermediate precision (Amersham, 1999) It is important to validate intermediate precision in rp-HPLC so that verification of same results being produced by same method in same laboratory following the phase of development could be possible. Reproducibility otherwise called ruggedness is simply inter-laboratory precision . It’s aim is to ensure that different laboratories will have same results using the method. Variables that affect the reproducibility of rp-HPLC include the varying operator experience, varying ages of equipment, differential supplies of columns, variation in humidity room temperature, different characteristics of equipment such as the delay capacity of HPLC system (Lebendiker, 2006). Accuracy is the degree in which test outcomes are proximate to the true value. This is obtained from outcome of quantitative assessment of a known sample. Whatever is measured is then compared to the known amount. Selectivity specificity These are usually interchanged . Selectivity of analytical method like rp-HPLC refers to its capability despite the presence of interference, to still be able to measure accurately (Guzzetta, 2010). Such interference includes enantiomers, degradation products and excipients. When selectivity of a method is verified, it becomes “Stability Indicating Methodâ€. Limit of detection This refers to the least amount or concentration of analyte in a chromatographic sample that may not be quantifiable but is detectable. In rp-HPLC, the limit of detection is that amount which after injected gives a maximum height of 2 to 3 times as raised as the reference noise level. Limit of quantitation refers to the least amount injected that results in precise measurement. In rp-HPLC, maximum heights of about ten to twenty times greater than reference noise are usually required at precision of less than 10-15% RSD between intervals of results. Linearity With injection of three to five series of four or more standards with spanning concentration of 80-120% expected range, the linearity of a rp-HPLC analytical method can be determined (Amersham, 1999). Whether directly or by calculation, it is expected that the response should be in proportion to the analytes’ concentration. The intercept of linear regression formula applied to these results should not substantially differ from zero. An intercept of significant non-zero should be followed by validation that there is no impact on method accuracy (Alveldano etal, 2010). Principle This operates of the separation of substances based on hydrophobic binding between the stationary/immobile hydrophobic ligand (called the stationary phase) and the solute in the mobile phase (Amersham, 1999). The binding interaction is presumed to be due to favorable entropy effect. The original mobile phase conditions in rp-HPLC are aqueous implying a highly organized water structure around stationary ligand solute molecule . The available area exposed to solvent becomes diminished with binding of solute to the stationary hydrophobic ligand. With this, there is decrease in organization of water structure increase system entropy (Amersham, 1999). In summary, rp-HPLC is based on “adsorption of hydrophobic molecules onto a hydrophobic solid support in a polar mobile phaseâ€. Reverse phase HPLC has also been utilized in most analytical methods.
A Comparison Of Machiavelli And Hobbes Politics Essay Machiavelli and Hobbes were the most important political philosophers of early modernity. Politically, modernitys earliest phase starts with Niccoló Machiavellis works which openly rejected the medieval and Aristotelian style of analyzing politics by comparison ideas about how things should be, in favor of realistic analysis of how things really are. He also proposed that an aim of politics is to control ones own chance or fortune, and that relying upon providence actually leads to evil. Machiavelli argued, for example, that violent divisions within political communities are unavoidable, but can also be a source of strength which law-makers and leaders should account for and even encourage in some ways. [1] Machiavellis recommendations were sometimes influential upon kings and princes, but eventually came to be seen as favoring free republics over monarchies. Machiavelli in turn influenced Francis Bacon, Marchamont Needham, Harrington, John Milton, David Hume, and many others. [2] Important modern political doctrines which stem from the new Machiavellian realism include Mandevilles influential proposal that Private Vices by the dexterous Management of a skilful Politician may be turned into Public Benefits (the last sentence of his Fable of the Bees), and also the doctrine of a constitutional separation of powers in government, first clearly proposed by Montesquieu. Both these principles are enshrined within the constitutions of most modern democracies. It has been observed that while Machiavellis realism saw a value to war and political violence, his lasting influence has been tamed so that useful conflict was deliberately converted as much as possible to formalized political struggles and the economic conflict encouraged between free, private enterprises. [3] As I said in the first paragraph of this essay I will start with Thomas Hobbes, attempts were made to use the methods of the new modern physical sciences, as proposed by Bacon and Descartes, applied to humanity and politics. Notable attempts to improve upon the methodological approach of Hobbes include those of Locke, Spinoza, Giambattista Vico and Rousseau. David Hume made what he considered to be the first proper attempt at trying to apply Bacons scientific method to political subjects, rejecting some aspects of the approach of Hobbes. [4] Modernist republicanism openly influenced the foundation of republics during the Dutch Revolt (1568-1609), English Civil War (1642-1651), American Revolution (1775-1783) and the French Revolution (1789-1799 A second phase of modernist political thinking begins with Rousseau, who questioned the natural rationality and sociality of humanity and proposed that human nature was much more malleable than had been previously thought. By this logic, what makes a good political system or a good man is completely dependent upon the chance path whole person has taken over history. This thought influenced the political (and aesthetic) thinking of Immanuel Kant, Edmund Burke and others and led to a critical review of modernist politics. On the conservative side, Burke argued that this understanding encouraged caution and avoidance of radical change. However more ambitious movements also developed from this insight into human culture, initially Romanticism and Historicism, and eventually both the Communism of Karl Marx, and the modern forms of nationalism inspired by the French Revolution, including, in one extreme, the German Nazi movement. Francis Bacon inspired by Machiavelli Francis Bacon (1561-1626) was one of the leading figures in natural philosophy and in the field of scientific methodology in the period of transition from the Renaissance to the early modern era. As a lawyer, member of Parliament, and Queens Counsel, Bacon wrote on questions of law, state and religion, as well as on contemporary politics; but he also published texts in which he speculated on possible conceptions of society, and he pondered questions of ethics (Essays) even in his works on natural philosophy (The Advancement of Learning). [5] After his studies at Trinity College, Cambridge and Grays Inn, London, Bacon did not take up a post at a university, but instead tried to start a political career. Although his efforts were not crowned with success during the era of Queen Elizabeth, under James I he rose to the highest political office, Lord Chancellor. Bacons international fame and influence spread during his last years, when he was able to focus his energies exclusively on his philosophical work, and even more so after his death, when English scientists of the Boyle circle (Invisible College) took up his idea of a cooperative research institution in their plans and preparations for establishing the Royal Society. [6] Bacons method for permeating his philosophical ideas into the collective unconscious of the age can best be summarised in his motto: bene visit qui bene latuit One lives best by the hidden life. Bacon resurrected the Rosicrucian Mystery School and the Freemasons, and injected new life into these secret fraternity societies so they became vehicles for the new Baconian philosophy of reason and scientific enquiry. Bacon, like Goethe, scorned knowledge that did not lead to action and also scorned the denial of evil in ourselves. Bacon was grateful to Machiavelli for his frank appraisal of the shadow side of human nature in politics: We are beholden to Machiavelli, and writers of that kind, who openly and unmasked declare what men do in fact, and not what they ought to do; for it is impossible to join the wisdom of the serpent and the innocence of the dove, without the precious knowledge of the nature of evil. Bacons works touch on all aspects of humanity politics, religion, theology, scientific method, but his most brilliant observations are psychological. Foreshadowing the discoveries by Carl Jung about the nature of the unconscious and the shadow side of man, Bacon recognized that the baseness of man should be recognized and dealt with openly, not repressed and personified as the devil. [7] In modern political vernacular, Bacon was a conservative. He saw an ideal Government as one which was benevolent without the worst excesses of despotism by rulers, or by the majority the same as Machiavelli. It is almost without instance that any government was unprosperous under learned governors.  [8] In science, Bacon sought nothing less than the reconstruction of a system that could be applied to the relief of mans suffering. He constructed a new Classification of Science (The Advancement of Learning, 1603-05), described a new method for the Interpretation of Nature (Things Thought and Seen, 1607, Thread of the Labyrinth, 1606, Novum Organum, 1608-20). He investigated the phenomena of nature in Natural History (1622), and showed how the writers of the past had advanced their truths to the time of Bacon in Forest of Forests, published in 1624. Bacon recorded anticipations of scientific results he felt would come from application of his methods in On Origins (1621). As a result of applying these principles, he described the basis of a new society that would emerge in The New Atlantis (1624). This Magna Instauratio, the great reconstruction, was inspired by the vision Bacon had in his youth, and was a herculean task without precedent in the history of thought. As Bacon stated in the preface to Magna Instauratio. and I am laboring to lay the foundation not of any sect or doctrine, but of utility and power. To Bacon, Knowledge is power, not mere argument or ornament. In Advancement of Learning, Bacon suggested that all areas of life had rational rules and an empirical basis: medicine, psychology, even dreams, predictions and other occult phenomena. Yet he comes full circle at the end of this survey, concluding that science needs to be guided by philosophy. Bacon applies this to politics. [9] Comparison Hobbes and Machiavelli on Human Nature Thomas Hobbes (1588-1679), whose current reputation rests largely on his political philosophy, was a thinker with wide-ranging interests. In philosophy, he defended a range of materialist, nominalist, and empiricist views against Cartesian and Aristotelian alternatives. In physics, his work was influential on Leibniz, and leads him into disputes with Boyle and the experimentalists of the early Royal Society. In history, he translated Thucydidess History of the Peloponnesian War into English, and later wrote his own history of the Long Parliament. In mathematics he was less successful, and is best remembered for his repeated unsuccessful attempts to square the circle. But despite that, Hobbes was a serious and prominent participant in the intellectual life of his time. [10] Thomas Hobbes and Machiavelli shared a commonality in the time period in which they each lived. Separated by approximately 100 years, both thinkers were focusing on political theory. Hobbes theory tended to focus on the social contract between a people and its government. Machiavellis theory focused on the attributes that formed a successful ruler. Examining both theories, a comparison is evident in that Machiavelli and Hobbes both seem to discuss the human nature of society. In Leviathan, Thomas Hobbes views human nature as individual self-preservation and as a place of constant war. There is a constant struggle between men. What causes this conflict amongst men? Hobbes believes that competition and glory causes war between men. He says, If two men desire the same thing, which nevertheless they cannot both enjoy, they become enemies to destroy one another. He concludes that self-preservation is the only way to safeguard from being destroyed. The only way to preserve one is to become more powerful than the other. Government must also be instituted to ensure peace and security through whatever means necessary. Hobbes believes that life without government would be poor, nasty, brutish and short.  [11] In the Prince, Machiavelli views human nature as pertaining to those who are ruled and those who rule. He promoted a secular society and believed that morality stood in the way. He distrusts people and believes that in a time of adversity, when the state is in need of its citizens there are few to be found. He questions the loyalty of the citizens. Because of this, he advises the Prince that, because men are wretched creatures who would not keep their word to you, you need keep your word to them. Machiavelli believed that the secular form of government to be the most successful. His views were to benefit the prince by maintaining power rather to serve the well being of the citizens. Hobbes and Machiavelli both have interesting ideas on Human Nature. Both of their ideas also contain an evident theme. The theme is the usage of fear as a means acquiring power and maintaining it. The theme of fear is not illustrated in great detail in Hobbes work as it is in Machiavellis. Nevertheless an interesting comparison can be drawn between the two.  [12] Hobbes believes that people naturally fear death. The easiest and safest way to avoid death was to create a centralized state. An autocracy would ensure the universal desire for life. According to Hobbes, people would give up their power collectively to one ruler. In turn, the people would shut up and do what they were told. The only right they would have would be the right not to be killed. They would live under a tyrannical ruler who had all powers to decide good and evil for the people. He believes that fear is essential to maintain power and authority of the people. This is evident in his text with, And covenants, without the sword are but words, and strength to secure a man at all. [13] Machiavelli poises the question to the Prince is it better to be loved than feared or vice versa He addresses this question in regards to what benefits a ruler more. He concludes that a prince cannot be both feared and loved. Machiavelli believes that it is better to be feared by the citizens. This is seen as an economy of violence in which fear is used by violence to invoke a lasting impression on the people. This economy must happen at the beginning on an event where the timing is equally important. The violent act must be made into a spectacle done in the open where people can see and judge. People judge by appearances, so what they see will affect their mentality. The more violent the act the more fearful the individual will be of the same act upon them. Fear in a sense is used by both authors to train the people. It must be instilled upon them in order to maintain a successful regime. It is like the training of an animal. The master must instill on the animal that he is in charge. If he does not then the animal will overpower the master. The master must make the animal afraid of him by punishing it when it does wrong. Eventually the animal will realize who is in control.  [14] Spinoza and Machiavelli ideas. Spinoza is one of the most important philosophers-and certainly the most radical-of the early modern period. His thought combines a commitment to Cartesian metaphysical and epistemological principles with elements from ancient Stoicism and medieval Jewish rationalism into a nonetheless highly original system. His extremely naturalistic views on God, the world, the human being and knowledge serve to ground a moral philosophy centered on the control of the passions leading to virtue and happiness. They also lay the foundations for a strongly democratic political thought and a deep critique of the pretensions of Scripture and sectarian religion. Of all the philosophers of the seventeenth-century, perhaps none have more relevance today than Spinoza. [15] Spinozas political thought draws from a number of sources, both classical and modern. As one commentator puts it, Spinoza formed new conclusions from facts and concepts borrowed from others. It is worth briefly considering some of the sources of the facts and concepts that he inherits. [16] At some point in the mid-1650s. Spinoza began studying Latin with Franciscus Van den Enden. Van den Enden was an ex-Jesuit and radical egalitarian with revolutionary tendencies. He was put to death in 1674 after having been found guilty of conspiring to depose Louis XIV in order to establish a free republic in Normandy. Van dan Enden was an anti-clerical democrat who appears to have profoundly influenced Spinoza. One commentator has gone so far as to call Van den Enden the genius behind Spinoza, claiming that Van den Endens writings contains a political theory which is in fact the same as the one worked out by Spinoza. Whether or not this assessment is fair, it is clear that Spinozas thinking was nourished through his association with Van den Enden and the larger radical Cartesian circle in Amsterdam. [17] Hobbes influence on Spinoza is unmistakable. We know that Spinoza read De Cive carefully and that it was among his possessions when he died in 1677. He might also have read Leviathan, which appeared in Latin in 1668, as Spinoza was completing the TTP, although we do not know this for sure. I will discuss Spinozas work in relationship to Machiavelli in some detail below. Here I want to mention the impact of Machiavellian on Spinoza. Machiavellian thought was introduced into Dutch political discourse by Lambert van Velthuysen, an anti-clerical, liberal physician. Velthuysens Dissertatio is an unabashed defense of Machiavelli thought, in which the duty to preserve one is given pride of place. Spinoza read and admired Velthuysen as a man of exceptional sincerity of mind, and was thus disconcerted when Velthuysen denounced the TTP as the work of a cunning atheist. [18] Aside from Velthuysen, the other primary Dutch conduits for Machiavellian thought prior to Spinoza were the De la Court brothers. Most of the De la Courts writings were published by Pieter De la Court after the death of his brother Johan in 1660. However, because it remains unclear how much Pieter added and how much he profited off his studious younger brother, I will refer to these authors of these writings simply as the De la Courts, so as to avoid attribution problems. The De la Courts were ardent republicans who maintained good relations with Johan De Witt. Indeed, De Witt is thought to have written two chapters in the second edition of their book Interest van Holland. The De la Courts adopted the basic features of Machiavellian anthropology, but eschewed juridical concepts like right and contract, opting to analyze the civil condition in terms of the competing interests of participants. According to them, the aim of the state is to ensure that the interests of rulers are tied to the interests of the ruled, which is possible only if one adopts a series of institutional measures, such as the use of blind balloting, the removal of hereditary posts, and the rotation of offices. Republics, they argued, will be marked by greater checks against self-interested legislation than monarchies. Spinoza evidently studied these works carefully; his institutional recommendations in the Tractatus Politicus. [19] It was likely the writings of the De la Courts that impressed upon Spinoza the perspicacity of Niccolo Machiavelli. The notion of balancing the interests of competing parties was ultimately derived from Machiavelli. Spinozas Political Treatise is shot through with Machiavellian insights and recommendations. Right at the outset of the work, Spinoza parrots Machiavellis critique of utopian theorizing, elevating statesmen over philosophers, since only the latter begin with a realistic conception of human psychology. Machiavellian realism pervades Spinozas political writings, playing a particularly large role in the constitutional theorizing of the TP. Spinoza, like Machiavelli, understood that prescriptions for improving the governance of a state can be offered only after one has a proper diagnosis of the problems and a proper grasp of human nature. [20] Machiavelli and Locke John Locke (b. 1632, d. 1704) was a British philosopher, Oxford academic and medical researcher, whose association with Anthony Ashley Cooper (later the First Earl of Shaftesbury) led him to become successively a government official charged with collecting information about trade and colonies, economic writer, opposition political activist, and finally a revolutionary whose cause ultimately triumphed in the Glorious Revolution of 1688. Much of Lockes work is characterized by opposition to authoritarianism. This opposition is both on the level of the individual person and on the level of institutions such as government and church. For the individual, Locke wants each of us to use reason to search after truth rather than simply accept the opinion of authorities or be subject to superstition. He wants us to proportion assent to propositions to the evidence for them. On the level of institutions it becomes important to distinguish the legitimate from the illegitimate functions of institutions and to make the corresponding distinction for the uses of force by these institutions. The positive side of Lockes anti-authoritarianism is that he believes that using reason to try to grasp the truth, and determining the legitimate functions of institutions will optimize human flourishing for the individual and society both in respect to its material and spiritual welfare. This in turn, amounts to following natural law and the fulfillment of the divine purpose for humanity. [21] John Locke and Niccolo Machiavelli are political philosophers writing in two different lands and two different times. Lockes 17th century England was on the verge of civil war and Machiavellis 15th century Italy was on the verge of invasion. The focus of this part of my essay is to examine the treatment of the people by both authors, to discover what Machiavelli and Locke write about the peoples role in their different structures of government. In particular, this paper seeks to understand that role in regards to the political power each author yields to, or withholds from, the people. In addition, these treatments of power and the people will be compared to the writings of another timeless political philosopher, Plato. By Discourses on Livy, The Prince, and The Republic against one another, this paper will show how writers from three very different centuries all agreed upon an identical notion of the relationship between the power of the people and their role in government. This theory is not readily apparent upon initial reading of these authors. Indeed, most political philosophers would argue that each author has a very distinct notion of what role the people play in government. Therefore, an ideal place to start is in the differences of each authors portrayal of the people and the political power they wield. Machiavelli, the most pessimistic of the three writers in regards to humans and human nature, writes that all men can be accused of that defect which Livy calls vanity and inconsistency. He continues by writing: …people are nothing other than a brute animal that, although of a ferocious and feral nature, has always been nourished in prison and in servitude. [22] Animals, that are by their nature ferocious, become scared and confused when released from captivity. Without the shelter and food they had come to expect when domesticated, they are more susceptible to future attempts at captivity. Man also becomes scared and confused in freedom after living under the government of others. Machiavelli writes that these men lack understanding of public defense or public offense, and quickly return beneath the yoke that is most often heavier than the one it had removed from its neck a little before. Men are docile like domesticated dogs or cattle, according to this description, and have a role in government of little political power. With Plato, there is a continuation of the same theme started by Machiavelli. [23] The oligarchic rule the city through the license of the multitude, and the orderly rule in business through the disadvantage of the multitude. Thus, Machiavelli sees the people as subjugated and Plato sees the people as fatuous, both doomed to political ineptitude. With Locke, however, the character of the people is redeemed. The people, for Locke, represent a political power akin to force. Indeed, the people are the ultimate source of power for Lockes government, whether that government is a legislative body or a prince. In the closing chapter of his second treatise, Locke details the ways that government can dissipate when rulers misuse their power. According to Machiavelli, …the people neither desire to be commanded nor oppressed by the great. In this sense, the people constitute a humor of the city, the opposing humor being the desire of the great to command and oppress the people. A man should be wary of becoming prince with the support of the great instead of the support of the people. Without their support, the prince is doomed to govern either a territory filled with an unmanageable great or a large body of unruly people. Indeed, Machiavelli echoes this in a later chapter by stating … a prince should have two fears: one within, on account of his subjects; the other outside, on account of external powers. [24] In both this text and Lockes Two Treatises, the authors yield an incredible amount of power to the people: the power to both influence the creation of and bring about the destruction of governments. For Machiavelli, the people are a large body of people, viewed as more formidable, and, therefore, more influential, than the great aristocrats in principality building. For Locke, the people exert a similar influence over the building of a commonwealth, since it is from the people that the power of the prince or legislature originates. Moreover, the people can decide to bring about the end of a particular regime of government if they feel that it no longer adheres to its responsibilities. Thus, the people, in both Machiavelli and Locke, appear to share a similar amount of power both in the formation of government and in its oversight: namely, that of adjudication. In the Discourses, Machiavelli writes of a cyclical succession of governments, one after another, each one rising to prominence only to fall to licentiousness. It is through this cycle that Machiavelli demonstrates the power of the people to adjudicate, and he argues that it is this adjudication that perpetuates the cycle. Kings rise to prominence based upon character, until the monarchy becomes hereditary and degenerates into sumptuousness and lasciviousness. [25] Machiavelli and Locke both considered the nature of government and mans individual interests as they relate to governmental structures. Machiavellis idea of fortune and Lockes state of nature concept both shaped the theorists arguments about the purpose of political life. It has been posited that for Machiavelli, politics is an unpredictable arena in which ambition, deception and violence render the idea of the common good meaningless, while Locke would argue that political or civil society exists only to preserve the rights of the individual. It can be argued that for both Machiavelli and Lock, political activity, then, becomes merely a means of satisfying selfish ends.  [26] Napoleón Bonaparte a follower of Machiavelli One of the greatest military commanders and a risk taking gambler; a workaholic genius and an impatient short term planner; a vicious cynic who forgave his closest betrayers; a misogynist who could enthrall men; Napoleon Bonaparte was all of these and more, the twice-emperor of France whose military endeavors and sheer personality dominated Europe in person for a decade, and in thought for a century. [27] In 1513, Niccolo Machiavelli wrote a piece of work called, The Prince. It was written to all principalities, and that which is parallel to what Machiavelli suggests is often referred to as being Machiavellian. The purpose of this essay is to ask the question Is Napoleon Bonaparte Machiavellian in Nature? By the evidence found from Napoleons life and accomplishments it can said that he was not Machiavellian in nature, which can be demonstrated by numerous accounts as well as some suggested characteristics given by Machiavelli, to support this theory. This essay will take a look at Napoleons leadership skills, his beliefs and ideals, as well as his personality that made him a great political figure. These aspects of Napoleons persona give a description of how his character was different from that in Machiavellis The Prince. In the area of leadership, Napoleon had many qualities that set him apart from the rest. Napoleon was a great leader but at times his people hated him. Machiavelli believed that, one cannot call it virtue to kill ones citizens, betray ones friends, to be without faith, without mercy, without religion; these modes can enable one to acquire an empire, but not glory. [28] Machiavelli said, it remains now to see what the modes and government of a prince should be with subjects and with friends. Apparently Napoleon was not a good friend considering when he was exiled the second time his friends that had been with him since the beginning were said to have killed him. Based on this it can be said that Napoleon does not display characteristics of being Machiavellian. Napoleon believed that he would be a much more successful leader if the people liked him. This is thought so because when he was trying to get political support by the people he did not user fear, he found something they all wanted to hear and he said them. Even though Machiavelli said, … it is much safer to be feared, then loved, if one has to lack one of the two. Napoleon also tried to make the people like him by setting up the Napoleonic Code, which was a set of laws that gave religious freedom and equality. Another illustration of Napoleons beliefs and, or ideals was, instead of appearing to have Machiavellian characteristics, Napoleon actually had them. Thus it is not necessary for a prince to have all the above mentioned qualities in fact, but it is indeed necessary to appear to have them. Napoleon was actually a feared leader and thought of people as disposable but Machiavelli only said to appear to have these traits. The final area of Napoleons behavior is his personality. Machiavelli stated, … it is very natural and ordinary to desire to acquire, and always, when men do it who can, they will be praised and not blamed; but when they cannot, and want to do it anyway, here lie the error and the blame.
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