Lord of Flies (Evil Nature) Essay Example for Free

Lord of Flies (Evil Nature) EssayIn life, there ar a lot of things that hold people spine from doing what they want to do. One of the major things is the laws of society. William Goldings novel, Lord of the Flies, illustrates what would happen without society. The boys behaviors change significantly throughout the novel. The boys carry their civilized behaviors with them to the island but, as time goes by without society, those behaviors are lost. When the boys are first dropped off on the island, they still have their civilized behaviors with them. Shortly after Jack is given the responsibility of leading the hunters, he is given the fortune to obscure a pig. However, Jack hesitates as he begins to understand what an enormity the downward stroke would be (etext) and misses his chance. Jack is still too civilized to kill the pig. The boys are also unable to come to terms with death in general at the beginning of the novel. When the boy with the mulberry birthmark dies, the bo ys never real talk about it and Ralph doesnt do a count of the boys because he doesnt want his death to become real.This illustrates how the boys still looking how normal, young boys feel and that their societal ways are still very much present on the island. As the novel progresses, the boys horror nature begins to become to a greater extent and more present. It starts off with their hunting. Jack goes from not being able to kill a pig because he is hesitant to killing them very violently. The hunters chant, Kill the pig. Cut her throat. press release her blood (etext). Although killing an animal doesnt seem bad, especially because they need to in order to survive, it allows the boys to think that killing is acceptable in general.Which leads to the hunters murdering Piggy and the come death of Ralph. The author of the novel, William Golding, states that the theme of the novel involves the evil nature humans naturally have that is held inside of them because of society. This i s true to a certain extent because around of the boys evil nature may be coming from the circumstance they are in. However, this is true because Golding shows as society and civilization deteriorate, so does the boys good human nature.As the boys start to realize there are no laws or other people on the island to hold them back, they start to show their true colors which is the evil nature they possess. The way humans behave is very much controlled by the type of society they are in. In the novel, Lord of the Flies by William Golding, the normal society is not present causing the natural evil behaviors humans have to be presented. Eventually, as the boys begin to realize their are no laws memory them back from doing wrong, the boys start to display this evil nature.

Love and sex in Geoge Orwells novel 1984 Essay Example for Free

Love and sexuality in Geoge Orwells novel 1984 EssayGeorge Orwells novel 1984 explores intimate human relationships in a bleak futuristic society as experienced by protagonist Winston Smith. Since there atomic number 18 few bonds stronger than those developed from loving relationships among family, friends, and applaudrs, the moreover entity acceptable to honor in Oceania is the face of the political party, Big Brother. This restriction is necessary to achieving complete power and control over its citizens, as the company must dissolve all loyalties derived through love, sex, and family and redirect them upon itself. By destroying trust the Party has rebuff the links between fry and parent, and between man and man, and between man and woman(220).To train the citizens of Oceania for complete sub delinquentdness and devotion to Big Brother and the Party the family bond has been completely devalued, as No one dares trust a wife or a child or a friend any longer.(220) The Junior Spies are an organization in which children have become the police and denouncers of their parents in the name of Big Brother. By this means, the Party has managed to wedge itself between one of the most powerful instinctual bonds to turn parental devotion into fear and children into faithful machines of the Party as an extension of the judgement Police. Parsons remark In fact Im proud of her. It shows I brought her up in the right spirit, anyway(193) in response to his daughters betrayal, clearly portrays the Partys influence in the family institution. Not only does the daughter value the Partys approval more than her fathers life, only when also Parsons appropriate response is to be grateful for the betrayal and to those who enforce it.The betrayal of the family bond is a common theme in 1984. Orwell illustrates how weak that loyalty has become with the skull-faced mans desperate begging to watch his wife and childrens throats be slit as an alternative to the Ministry of Loves populate 101 with a complete lack of private loyalties(136). Winstons memories of his mothers love in a time when there were still privacy, love, and friendship, and when the members of a family stood by one another(prenominal)(prenominal) without needing to know the reason(28) confront his suspicions that to remain human, one was not loyal to a party or a country or an idea, they were loyal to one another(136).Technically, consorting with prostitutes is forbidden, but it seems to be tacitly encouraged just the same, as a means of relieving natural tensions. The more serious crime involves relations between Party members. The Party does not wish to allow the development of loyalties to any other acts or persons than itself, so it tends to deny permission of marriage to couples who appear attracted to one another, and it campaigns actively against sex as anything other than a slightly disagreeable duty whose sole purpose is propagation of the species. The Party feeds off the h ysteria produced from sexual privation, as it is hands down transformed into war fever and leader worship(110).Through its control of marriages and sexual mores, the Party resembles a conservative religious institution. By attempting to control peoples loyalties and loves, and redirect those towards itself, the Party posits itself as the end and the ultimate salvation. Katharine even calls sex our duty to the Party, and it is a weekly ritual almost like a martyrdom, in which both she and Winston are uncomfortable but must suffer through it anyway.Clearly, Winstons confide to have a woman of his own with whom sex could be pleasurable is yet another instance of his heretical tendencies. It does not seem something that he has experienced yet, since his encounter with the prostitute was somehow dirtying in every sense. His desire to evoke desire is itself thoughtcrime, and part of his overall rebellion against the world he lives in.. The Junior Anti-Sex League is one of the propaganda organizations used to control desire and teach sexual orthodoxy. The Partys sexual puritanism is due to the fact that the sex instinct creates a world of its own(110) and is therefore out of the Partys control and must be destroyed The sex instinct exit be eradicated. Procreation will be an annual formality like the renewal of a ration card. We shall abolish the orgasm(220). The sex instinct is dangerous to the Party and makes a direct, intimate connection between chastity and political orthodoxy(111). Sex is an act of outright rebellion, as all enjoyable sex must be in a society where the act issupposed to be free of pleasure. In this sense Winstons affair with Julia is a political act against the Party, which is part of the attraction. Perhaps the superlative crime they commit is declaring love for someone as an individual, someone who is separate from the Party.Love, the clear anti-thesis to everything the Party stands for, has heavily ironic meaning in 1984. The language alon g with the emotion is manipulated by the Party to gain control of the people. The Ministry of Love, for example, concerns itself with torture, and the destruction of the individual is referred to as love for Big Brother.Winston battles to discover his humanity by equating the capability to feel love with the essence of being human. Winston progresses from seeing Julia as an outlet for his political unorthodoxy and his sexual energy, to seeing her as a companion, linked to him in a marriage of love. As long as Winston loves Julia, and what she represents to him, he is able to believe in himself and his humanity enough to hate Big Brother. Once he betrays that love, he violates his own humanity and can no longer love another human All you care about is yourself(240). The Party, through Winstons betrayal of Julia, has cut another link to loyalty derived by love and redirected it upon itself. Winston is left a shell of a man having won the victory over himself and learned to love Big B rother (245).The goal of the Party is to wipe out the individual There will be no loyalty, except loyalty toward the Party. There will be no love, except the love of Big Brother.(220) In 1984 Orwell warns about the future of man who is doomed to lose his individualness without love and loyalty. Family, sex, and love are the anchors that postulate the emotions of human essence to our individual selves, resulting in Ownlife.

Effect Of Growth Factors Fcs On Cell Proliferation Biology Essay

Effect Of Growth Factors Fcs On Cell Proliferation Biology Essay initiationThe technique in which stalls normally of one type, removed from animal tissue ar grown in presence of supplements and growth factors under controlled conditions is called Cell Culturing. diverse cellphones require different conditions of temperature and gas for their appropriate growth in a cell incubator moreover growth media plays a crucial role in cell culturing, which can vary in glucose concentration, pH, growth factors like fetal calf serum (FCS).The effect of one of the above mentioned variables, we are going to adopt in this experiment is growth factors. Growth factors as the name suggests enhancers the growth which supplements the media are obtained from animal blood such as calf serum.Cell proliferation is examine by various methods, mainly used methods involve measuring the colour persuasiveness taken up by desoxyribonucleic acid of cell during cell proliferation in presence of staining dy es e.g. quartz royal and MTT (3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide).The aim of this experiment is to study cell proliferation by using crystallisation violet and MTT methods while using pilfer Y1 adrenocortical cells under the effect of growth factor FCS. pinch Y1 adrenocortical cell are grown in Dulbeccos modification of Eagles mass medium as monolayer cultures.watch glass VioletIt is biological stain used in cell proliferation method which stains DNA of the cells after permeabilisation with methanol. The positive ammonium ions of crystal violet stain DNA of cells in blue colour.The colour intensity produced is directly proportional to number of cells, which is determined in stain cells by colorimeter. Staining with crystal violet and MTT are based on principal of absorbance.MTTThe MTT assay is a standard colorimetric assay in which activity of reductase enzymes are measured which convert MTT to blue indissoluble formazan. The metabolic activity of viable cells is used as basic parameter in MTT assay. The tetrazolium salt, MTT is now widely used in quantitative measurement of cell proliferation. This method depends upon uptake of MTT by viable cells, which is a water supply soluble tetrazolium salt producing a yellowish solution. MTT is cleaved to insoluble blue formazan in the mitochondria of living cells by succinic dehydrogenases in the mitochondrial respiratory chain.Material UsedMouse Y1 adrenocortical cells, Dulbeccos medication of Eagles medium (DMEM) containing 10% Fetal calf serum, 2mM glutamine, 100u/ml penicillin and 100mg/ml streptomycin, crystal violet stain (0.1% solution in 200mM boric acid), MTT (5mg/ml MTT solution in PBS), PBS methanol, 10% glacial acetic acid, distilled water, acid-isopropanol.Apparatus used stratified flow cabinet sterilized two 96 well plates, multi well pipettes, pasture pipettes, sterilized T-flasks, sterilised empty reservoirs, gas incubator, fume water closet, spectrophotometer etc. m annerCells of mouse Y1 adrenocortical were separated from their substratum with tris in EDTA as they grow in monolayer cultures. Then added same volume of medium and centrifuged after that number of cells were counted on haemocytometer and diluted to concentration of 1.25 105 cells/ml and made it up to 30 ml.Then cells were passaged into centre 60 wells of 96 well plate in duplicate with concentration of 0.25 10 cells/ 200l in each well while outside wells of 96 well plate were fill with same amount of phosphate buffered saline (PBS) and allowed the cells to incubate overnight at 37 C temperature in humidified gas incubator. by and by that cells were washed with PBS tercet times and different wells of each plate were do by with different concentrations of FCS which is shown in table 1.Hence 12 wells of each plate were treated with 0, 1, 5, 10 and 20% v/v concentration of FCS and both plates were incubated for 72 hours.One plate was used for crystal violet staining method and s ome other for MTT assay.Table 1Dilution of FCS% FCSVolume of Serum(ml)Volume of Medium (ml)001010.19.950.59.510192028 crystal violet staining methodFor this method cell media was removed first of all from incubated plate and then cells were washed with PBS. later that were fixed with 200l of methanol for 15 minutes in fume cupboard. Then methanol were removed and cells were allowed to dry in fume cupboard for few minutes.Then cells were treated for 20 minutes with crystal violet stain 200l/well. Later cells were washed three times with distilled water and stained cell layer was allowed to solubilised in the 50l of 10% glacial acetic acid and plates were incubated for 30 minutes in gas incubator.After that absorbance of each well was read by plate reviewer spectrophotometer set at 540nm.MTT MethodTo perform MTT assay, each of centre 60 wells of 96 well plate was treated with 20l of MTT solution and plate was incubated for 4 hours at 37o C temperature in gas incubator.After 4 hours, the medium was removed from each well and 100l of acid-isopropand was added to dissolve blue formazan crystal in the cell layer. Then plate was incubated for 30 minutes at room temperature.When blue formazan crystal were solubilised, absorbance of each well was measured at 570nm using the plate reader.CalculationsCells in five consecutives of Haemocytometer = 24Volume of each square is =4-10-3lThe no. of cells in five squares multiplied with 5-104 gives no. of cells in 1ml.Hence no. of cell in 1ml = 1.2-106 cells/ml call for cell breach = 1.25-105 cells/mlDilution Factor = Concentration Required/Concentration gotDilution Factor = 0.104Therefore, in order to make 30 ml of cell suspension 3.125 ml of cell suspension was mixed with 26.875 ml of medium.Similarly 30 ml of cell suspension was prepared having 1.25-105 cells/ml.ResultsObservation Table for crystal violet staining method%FCSAverageStandard Deviation00.2050.021810.2550.030750.3090.0450100.4320.0614200.5810.0844Table2 Data o btain from plate reader at 540nmGraph showing effect of FCS with Crystal Violet MethodAbove graph shows that with increase in serum concentration the absorbance increases, which is directly proportional to cell number.Observation Table of MTT staining method% FCSAverageStandard Deviation00.0940.008110.1150.013850.1520.0191100.2760.0724200.4000.0807Table3 Data obtained from plate reader at 570nm.Graph showing effect of FCS with MTT stainingAbove graph shows that with increase in serum concentration the absorbance increases, which is directly proportional to cell number. intelligenceCrystal Violet Staining method and MTT Assay is based on principle of absorbance, more is colour intensity, more will be the absorbance value.The result of Crystal violet staining method clearly indicated that absorbance value was directly proportional to cell proliferation as it was increasing with concentration of FCS.FCS stimulated Cell ProliferationResult in more cells and DNAMethanol increased cell me mbrane permeabilityResult in more stained DNAMore Colour intensityHence More Absorbance ValueSimilar results were seen in MTT Assay but in this assay only viable cells were stained while in crystal violet method both viable and non viable cells were stained. So Crystal Violet method of staining is not specific staining technique because in this absorbance is not direct index of cell viability.The drawback of MTT Assay is that some reducing agent may reduce MTT also which could show slight increase in absorbance, moreover this method depends on some variable like pH, presence of D-glucose and pyridine nucleotides which can affect the specificity of Assay.In spite of above said limitations these methods are broadly followed because they are safe, simple, cheap and reproducible. eminence of K562 cells to megakaryocytes/plateletsTo study cell differentiation of K652 cells chronic myelogenous leukaemia, K652 cell line, indicates an early differentiation stage of granulocyte lineage. K65 2 cells are non-adherent, circular shaped with petite microvilli.In the presence of tumour promoters like phorbol myristate acetate (PMA) these type of cell are differentiated to megakaryocytes.The induction of megakaryocytic differentiation of K652 cells is known to be initiated by two signalling pathways which are the nuclear factor kappa B(NF-B) -depends pathways and other is extracellular signal regulated kinase (ERK)/mitogen activated kinase (MAPK) dependent pathways.Human chromic myelogenous leukemic cells, K652 cells have Philadelphia chromosome. Tumour promoter, PMA which is a pissed mitogen for human peripheral blood lymphocyte also act as a protein kinase C (PKC) activator which differentiate K652 cells to megakaryocytes.The various changes that occurs during differentiation of K652 cells areChanges in cell morphologyCell growth arrestAdhesive properties of cell changeExpression of markers associatated with megakaryocytesEndomitosisNADPH oxidase complex which is know n as a primary source of ROS (Radio prompt oxygen species), is initiated by PMA.PMA stimulates NADPH ROS (Signalling Molecule)Induction of gene reflectivity is directly related with ROS.The Expression of CD61, a platelet cell marker helps in identifying differentiated cells. The expression of CD61 can be seen on platelets, osteoclasts, macrophages and on some tumour cells, involved in tumour metastasis and in adenovirus infections.Results and DiscussionIt was observed that PMA treated slide was stained pink while cells devoid of PMA were stained blue as shown in Pic. 1 2. In PMA treated slide the K562 cells were clearly differentiated to megakaryocytes which suggested that tumour promoter, PMA bring on differentiation in K562 cells by signal transduction and expressed by CD61 as shown in picture below.CUsersmkkaushalPicturescell bio picsmail2.jpg Pic. 1PMA Treated Cells clearly showing Differentiation to MegakaryocytesCUsersmkkaushalPicturescell bio picsmail.jpg Pic. 2Cells Devoi d of PMA stained blue in ColourThe expression of CD61 was recognised by addition of rabbit anti-mouse IgG antibodies that bind to CD61 antibodies when incubated in presence of alkaline phosphatise anti alkaline phosphatise (APAAP) complex.The cells were stained pink because fast red dye get attached to APAAP so this is how CD61 was expressed in cell treated with PMA. Moreover cells treated with PMA were larger, irregular, in shape and fewer in number as compare to untreated cells.On the contrary, Cells devoid of PMA were much smaller in size than treated cells.Diagramatic Representations of ImmunocytochemicalReactions To Detect CD61PMA Treated Cells PMA Untreated CellsCD61 bound to both treated and untreated cellsThen Cells are washed toRemove CD61 unbound Treated with RAMThen RAM binds to APAAP and cells are stained pink in colour. Mouse Antihuman CD 61 (PrimaryAntibody) Rabbit Antimouse IgG (RAM-Secondary Antibody) Mouse Alkaline Phosphate AntiAlkalinePhosphatase(APAAP Tertiary Antibody)

Wind Stability Engineering in High Rise Buildings

Wind Stability Engineering in spirited Rise BuildingsIn building construction, on that point is a reciprocal relationship between forces within and away to the structure that directly affect stability and pineevity. Fundamentally, damped oscillations operate within a placement where a resistance (oftentimes passive) is applied to the structure in direct conflict with the natural or imposed oscillation, thereby stopping the movement (Knight, 2007).Forced oscillations also feign upon a structure as harmonic resonance is neared. In such agreements, there is a natural oscillating frequency (number of oscillations completed per second) which operates within the structure, and an external force termed the driving frequency which acts upon the system. Large differences between these two forces do not actively define the amplitude of the oscillations however, when they are numerically equal to all(prenominal) other, harmonic resonance results, highlighting the maximum amplitude of the system (Knight, 2007). Damped systems utilise force to mortify the affect of oscillations on structural integrity, thereby preserving the lifecycle of the building.To design and fitly calculate the functions of a damped harmonic oscillator, the following components are needed where is equal to a constant and is equal to the structural mass.This formula represents several functions of the structural stability including where in which a critically damped case arises and equilibrium is quickly established where the system is over-damped and equilibrium is slowly reached and where the system is under-damped and exhibiting transient behaviour (Elert, 2007).Perhaps the nigh famous example of harmonic resonance leading to structural deformation, the Tacoma Narrows Suspension Bridge in the United States has been oft studied by scientists and scholars to determine the labored collapse. The product of a galloping oscillation, this structure was subjected to high hint forces (35mp h) which excited the bridges transverse vibration mode, resulting in troika hours of motion with an amplitude of 1.5 feet (Irvine, 1999). A supplemental increase in wind to 42 miles per hour caused dampening cables to snap, resulting in an unbalanced load condition that increased the amplitude to 28 feet, and ultimately ended in collapse (Irvine, 1999). More modern examples of structures functioning under the support of dampers include Victory Monument on Poklyonnaya Hill in Russia which features three dynamic oscillation dampers, fifteen flexural oscillation dampers, and one torsional oscillation damper (High-Rise Constructions, 2008). Representative of a system utilising both active and passive damping forces to reduce structural vibrations, this structure rises 141.8 m and retains a skeletal framework of steel latticework, requiring the enhanced oscillation damping.In high rise building construction, oscillations due to wind forces acting in both elongated and non-linear capac ities directly contribute to structural instability. Etkin and Hansen (1984) note that within such systems, artificial dampers limit the motions and resulting stresses and with a ending of the amplitude of response consistent with wind related variables, predictive measures can identify the maximum reaction. Similar forces directly contribute to structural destabilisation, undermining integrity through resonance and incumbent force variables. In 1994 a crane in Germany demonstrated the influence of galloping induced oscillations as it was destroyed by fatigue cracks in the tension bars during the bending mode at resting state (Hortmanns and Ruscheweyh, 1997). Resulting from wind based forces in a state of quasi-stationary vibrations, such structural conflicts oftentimes overtake in large scale construction applications and cylindrical structures (Hortmanns and Ruscheweyh, 1997). Theoretical investigation of multiple vector damped linear systems has determined that resonant modes are free of twosome due to the damping forces, causing the system to behave as a sum of independent one-dimensional subsystems (Mathieu, 1965). The initial formulaic calculation for such a system is as followsWhen coupled with Raleighs assumption of proportion between stiffness and damping, this formula enables multiple variable calculations within a linear system that are mathematically independent of system counterparts (Mathieu, 1965). Effective in determining the relationship between frequency and harmonic balance at differing segments as hygienic as varied temporal intervals, this equation is one more step towards comprehensive structural analysis. Considering that high rise structures demonstrate an incidence of wind-generated harmonic unite as well as torsional sinusoidal wave vibrations based on innate building oscillations, calculating amplitude at varied temporal positions offers long term predictions of stability and maximum collapse potential (Katagiri et al., 2001).T he preceding sections demonstrate the innate relationship between harmonic resonance and the forces which act both internally and externally to a structure. Ultimately, resistance is derived through damped systems or a forced resonance, thereby counteracting the effects of wind, torsional movement, and ground shifting. More modern investigation into differentials between linear and non-linear systems as exemplified by exploiting Raleighs formulae in Mathieu demonstrate that variables within the resonant system oftentimes operate individually, thereby prescribing unique forces without concurrent incidence within counterparts. Long term implications of such predictive mechanisms include dynamic damping integration which acts on a sector basis to minimise torsion.ReferencesElert, G. (2007) The Chaos Hypertextbook. Glenn Ellert. Accessed on 29/11/08 From http//hypertextbook.com/chaos/41.shtml.Etkin, B Hansen, J.S. (1984) Effect of a Damper on the Wind-Induced Oscillations of a Tall Mast . daybook of Wind Engineering and Industrial Aerodynamics, Vol. 17, pp. 11-29.High Rise Constructions. (2008) Melnikov Institute. Accessed on 29/11/08 From http//www.stako.ru/show_prj_list.php?id=arch_highlang=engdata=arch_highprn=yes.Hortmanns, M Ruscheweyh, H. (1997) Development of a Method for Calculating Galloping Amplitudes Considering Nonlinear Aerodynamic Coefficients Measured with the Forced Oscillation Method. Journal of Wind Engineering and Industrial Aerodynamics, Vol. 69, pp. 251-261.Irvine, T. (1999) The Tacoma Narrows Bridge Failure. December. Accessed on 29/11/08 From http//www.vibrationdata.com/Tacoma.htm.Katagiri, J Ohkuma, T Marikawa, H. (2001) Motion Induced Wind Forces Acting on angulate High-Rise Buildings with Side Ratio of 2. Journal of Wind Engineering and Industrial Dynamics, Vol. 89, pp. 1421-1432.Knight, R.D. (2007) Physics for Scientists and Engineers. New York Pearson Education.Mathieu, J.P. (1965) On Damped Vibration Theory. International Journal of M echanical Science, Vol. 7, pp. 173-182.

Photopolymers for Tissue Engineering Purposes

Photopolymers for Tissue Engineering PurposesDISCUSSSION Tissue Engineering offers the potential to grow the cartilage in a fine shape and requires minimal operative time. In most of the preliminary studies, a prefabricated check is utilisation to grow the chondrocytes and obtain a tissue-engineered cartilage. However using the mold techniques is time consuming, does not provide an aesthetic framework for growing the cartilage and at that place is an uneven growth of cartilage tissue oer the framework. 3D blackguard manufacturing provides an alternative technique whereby one go off accurately fabricate an ear shaped scaffold mistakable to the normal ear. Approach in scaffold invent must be able to create porous structures to attain desired machinelike properties and to produce these structures within arbitrary and complex three-dimensional (3D) anatomical shapes. significant chemistry along with fabrication technique determines the properties that a scaffold can achieve and how cells interact with the scaffold .There are many techniques which are used in additive manufacturing wish well Stereolithography, Fused deposit modeling, selective laser sintering. Stereolithography exhibits the capability to control the spatial organization of multicellular material compositions with precise porous structures and delimit shape according to patient obtained from any medical imaging modality data. In this study, we accomplished stereolithographic fabrication of hybrid scaffolds using visible lightsomeness bothe symmetryn by using a commercially available low cost 3D printer. The scaffolds fabricated as such will be suitable as a photo curable material that could offer an ideal environment suitable for cell growth and provide the mechanical support for the regenerative process. The table shows on-line(prenominal) studies that have made use of photo curable biomaterial that can be used for tissue engineering process. Figure 6.1 Current studies involving phot opolymers for tissue engineering purposes As explained in the above table in that respect are many studies, which use biodegradable polymers that can be fabricated using the stereolithography technique. However, in most of these studies there are no such combinations of natural and synthetic polymers. Also in many studies, the material has been cross-linked in the lab by using a light source or by a modified/custom made 3D printer. For this study, we decided to use a low cost and a commercially available 3D printer (Formlabs Form 1+) and natural and synthetic available polymers without making any modifications. PEG is one of the most commonly used synthetic photo polymers for tissue engineering applications. For photo polymerization process the end group of PEG are modified into methacrylates, di acrylates, fumarates,vinyl radical esters etc and used for the polymerization. The reactivity of vinyl monomers towards free-radical chain polymerization follows this sequence acrylate vi nyl ester vinyl carbonate methacrylate fumarate. Due to the high reactivity rate we have decided to make use of acrylated PEG. Acrylated PEG enables photo polymerization with variable mechanical properties, but by itself, PEG cannot provide an ideal environment for cell growth despite having possessing properties like nontoxicity, low protein adhesion, and nonimmunogenicity. Also PEG does not possess the ability to degrade by itself. When it comes to biocompatibility issues, natural polymers are generally thought to be advantageous over synthetic hydrogels since natural gels may offer biological property to surrounding cells. Most naturally-derived polymers are either components of natural ECM or provide similar properties that can mimic the ECM properties. One such natural, biocompatible,and biodegradable polymer used to generate hybrid hydrogels is chitosan, an N-deacetylated derivative of the polysaccharide chitin. Although there is a study thatshows the photopolymerization of oligomeric chitosan with PEGDA polymeric chitosan has not been successfully polymerized with PEGDA. Chitosan is structurally similar to glycos aminicglycans (GAGs) found in cartilage and is degradable by enzymes in humans. The objective of the study was to get a hybrid copolymer of Chitosan and PEGD which can be 3D printed by stereolithography. To create the rosin we dissolved the chitosan in acetic acid. The acetate anionsdeprotonate the primary amino groups of chitosan. So it became necessary to dialyze the chitosan tooth root in a strong basic group solution like a sodium acetate. Dialysis of chitosan solutions in sodium acetate partially neutralizes the protonated primary amino groups. Such partial de-protonation of chitosan enab conduct mixing of photo initiators for polymerization of PEGDA without quenching the radicals formed by protonated amino groups. Because of the high degree of crosslinking of short chain PEGDA, caused by a higher concentration diacrylate groups compa red to long chain PEGDA a commercially available PEGDA 575 was used. In absence of Chitosan the minimum concentration required to create the printable resin was 30% (w/v) . However as shown in table the amount of PEGDA using Chitosan was centred from 30% to 6-9 % . Once the printable formulation was obtained it was necessary to test the mechanical and cellular properties of these scaffolds.Schematic of cross linked hydrogel with mesh size and crosslinking distanceWhen a hydrogel is kept in the solvent the solvent molecules try to enter interior by the capillary action. As more molecules enter the hydrogel the mesh size increases and more of the solvent is absorbed. However, the glob is not a continuous process and when the capillary forces balances the elastic forces of the network the equilibrium is reached. Q1/3 * (2)1/2where Q =swelling ratio and = distance between two crosslinking points.As evident from the figure and the equation there is a direct relation between the swe lling ratio and mesh size. As the amount of the PEGDA concentration increases, the degree of the crosslinking has increased. Highly cross-linked hydrogels will have a tighter structure, and will swell less compared to the same hydrogels with lower crosslinking ratios. Crosslinking hinders the mobility of the polymer chain and hence lowers the swelling ratio. As evident from Fig the mechanical modulus of the hydrogel was inversely related to the swelling ratio. As the ratio of PEGDA increased from 5 to 15, the elastic modulus increased by approximately seven times in both LMWC and HMWC Chitosan. As the swelling ratio decreases the increased resistance of the hydrogel contributes to the increase in Youngs modulus. Diluted PEGDA, without chitosan, at 30% (w/v) had the highest stiffness with a compression modulus of 1125 68.05 kPa (Mean SD). It was observed that the gel was capable of recovering to its original length following even with a 50% strain deformation.It is evident that in creasing the ratio of the initiator will increase the crosslinking density which will reduce the mesh size and in turn increase the modulus of the hydrogel.As evident from the swelling ratio the hybrid hydrogel had a higher swelling ratio than pure PEGDA which led to higher pore size which was proved with the SEM Imaging side

Nabokovs Spring in Fialta :: Essays Papers

Nabokovs Spring in FialtaSpring in Fialtas opening line, Spring in Fialta is cloudy and dull, (Nabokov 413) is quite an atypical beginning for Nabokov. This line, coming from a man who is overly concerned with trifles, brings up many questions. Is Nabokov intention on the wholey leaving out the trifles of Fialta present at the beginning? If so, why? Perhaps the answer to this question is that Nabokov intends for the line in question to be a double entendre referring to both the town and the composition itself. On the narrative level, Nabokov leaves little to the readers imagination. The story is dull and commonplace. Moreover, I found Douglas Fowlers criticism of the story to be off the checker and reaching. Fowler is looking too deeply into a cut and dry romantic parody, which bears a striking resemblance to Pushkins Eugene Onegin. Ninas imminent death is mentioned all over this story. These statements are so direct that it cannot be called foreshadowing. predict is m uch more subtle, like seeing a dead bird or something. Foreshadowing is definitely not like what is in Spring in Fialta, which is more like, Yup, shes gonna die. For example, the lunch with Nina where, for the last time in her life, was busy eating the shellfish of which she was so fond, (Nabokov 427). There are many more statements, some not quite as direct as these, but direct nonetheless such as when Victor is imagining her Had I to submit before judges or our earthly existence a specimen of her average pose, I would have maybe placed her leaning upon a counter at Cooks, left calf crossing right shin, left toe tapping floor, sharp elbows and coin-spilling bag on the counter, while the employee, pencil in hand, pondered with her over the plan of an eternal sleeping car. (Nabokov 417) Also, very early on, Victor says he cannot imagine any heavenly steadfast of brokers that might consent to arrange me a meeting with her beyond the grave, (Nabokov 415).Statement s such as these makes the reader so used to Ninas death that at the terminate of the story when she finally dies, the reader feels no sadness towards this event. There is no tugging at the heartstrings.

my sister :: essays research papers

The Life of Susan snowsusan snow was born on January 28, 1975. Her birth brought double the joy to her family who just minutes before had rejoiced upon the birth of her identical gibe sister, rachelle. She was a small premature baby born nearly five weeks early and remained in NYU Medical Center for a week under paying attention scrutiny. Her father and four older siblings eagerly anticipated her arrival at home. The family resided in brooklyn, where they still make their home, and susan joined them there. She was named susan bella after her paternal great auntie and great great grandm other. susan had soft brown hair and big blue eyes that sparkled with personality, despite her young age. After five long months of incessant crying, she lastly became an enjoyable and fun loving baby.susan attended a local school for her preschool and elementary school years. Throughout her school years, susan excelled in all subjects, although her talkative record often got her into trouble. She was so popular with her classmates, that at one point when the classes were switched, her friends left no stone unturned to get her back into their class. She enjoyed switching classes with rachelle and performing other mischievous tricks to fool the teachers that only twins can pull off. Her supreme intelligence was one of the reasons she was chosen as English Editor of her eighth home run yearbook and editor of the grade newspaper. Shani spent her summers in the catskills where she was adored by campers and counselors alike because of her sunny disposition. At age thirteen, she began attending camp snob and spent four thrilling summers there.susan decided to attend H B High School in brooklyn and is currently enjoying her third year there. She is know as a conscientious student who loves to have a great fourth dimension. There she likes being in the same class as rachelle, for the first time since kindergarten. One may think that these circumstances would provoke competition b etween them, but susan is non affected by competition at all. On her long time off she likes sleeping late, shopping, and spending time with friends. She also takes great pleasure in curling up in bed with a good book. susan is come to in various projects throughout the community and loves helping her family and friends in their times of need. She sleeps at her grandmothers house during the week so as not to leave her grandmother alone.