3

3.The framework of This Study:
To analyze the security and performance implications of different consensus and network layer protocol author has prepared a quantitative framework to carry out this study. Author’s framework is a combination of two key elements.

Figure:6 Components of Study Framework
** Pictures taken from ETH Zurich Research Report.

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They are (i) POW Blockchain and (ii) Security Model. A blackchin instance is a proof of work blockchain instantiated by consensus layer and network layer parameter. As discussed earlier a consensus mechanism is what all the blocks in the network follow to validate a transaction. For example, Bitcoin uses a POW consensus layer mechanism which searches for a nonce value such that the current target value should be lesser than the hash value. In network layer two most important parameters for POW blockchain is
Block size: This defines how many transactions can be put into each block. If the block size is bigger then block propagation speed decreases. On the other side, it increases the stale block rate.

Information Propagation mechanism: This shows how information is delivered in peer to peer network. There are four types of standard information propagation mechanism:
Send Headers: Peers can directly issue a send header to directly receive block headers from its peer in future.

Unsolicited Block Push: A mechanism of broadcasting blocks by the miners without advertisement.
Relay Networks: It enhances the synchronization of miners of the common pool of transaction.
Hybrid Push/Advertisement System: A system which combines the use of push and advertisement system.

In the left-hand side, POW blockchain takes consensus and network parameters as input and gives output like block propagation time, throughput. To realistically capture the output of this POW based blockchain authors have put this blockchain on the simulators they have developed. These simulators take input parameter such as block interval, mining power as well as block size, propagation protocol, the location of miner’s etc. Stale block rate is an important output from this POW based blockchain because it gives the efficiency of peer to peer connection of an honest network. This Stale block rate is taken as an input to Security model. This model also takes different security parameters as input such as adversarial mining power, mining cost, number of required confirmation. The main objective of this model is to holistically compare the security and performance of different POW blockchain with different parameters as input. This security model is based on Markov decision Process and provides an optimal adversarial strategy for double spending and selfish mining as an output.
3.1Security Model:
Parameters for the Security Model:
Stale Block Rate: Stale block rate captures information propagation mechanism.

Mining Power: This is typically used in the study model to capture the fraction of the total mining power possessed by the adversary.
Block Confirmation Number: Total number of blocks required to confirm a transaction.

Impact of Eclipse Attack: This study model accounts for eclipse attack as well.

3.2 Markov Decision Process: (MDP)
The right tool for a problem which handles with “states” and “discrete events” with probability is a Markov Decision Process (MDP). These are mathematical model which decides the best policy means in what sequence the actions should be implemented to achieve maximized goal. An MDP model has multiple states and actions. Actions are the transitions between states. In MDP each transition can happen with some probability. In this model, some actions might provide a reward or loss to occur. Figure 7 shows a “graphical depiction of a Markov Decision Process”. In the intended security and performance of POW study, MDP is based on four tuples. It is represented as follows M:=<S, A, P, R>. Where S represents state space, A is for representing actions, P is the stochastic transition matrix and R is the reward matrix.

Figure 7: A graphical depiction of MDP with states s_0, s_1, S_2 and action a_0, a_1.The two rewards are -1 and +5. “(Figure created by MistWiz on WikiCommons)”.

In this model an adversary can perform the below actions:
Adopt: If an adversary thinks it can never win over an honest miner then it performs this action.

Override: If adversaries chain is longer than the honest miner then it overrides the honest mining chain.

Match: if the length of adversarial chain and honest chain are same then adversary perform this action.

Wait: If an adversary has not yet found a block then it continues mining until it finds one.

Exit: This action is performed during the double-spending attack.
Now state space S also has four-tuple namely length of honest chain, length of adversarial chain, blocks mined by eclipsed victim and fork. In the research, paper MDP model can justify when an attacker can double spend or selfish mine.

Selfish Mining vs Double Spending: Main goal in selfish mining is to increase the relative share of the adversarial block in the main chain. In double spending, the adversary is more focused on earning maximum revenue. It is also found in the study that selfish mining is not always rational. Following an adversarial strategy for mining 1000 blocks with 30% hash power, an adversary can mine 209 blocks, but an honest miner can mine 300 blocks. In honest mining, an adversary can earn by mining a block. It also loses it’s reward if a block is adopted by the main chain. As the main chain poses maximum hash power, the probability is always high for an adversary to lose the competition.
Eclipse Attack: In this type of attack attacker takes control of peer to peer network and obscure target node’s view of the blockchain. The researcher has found attacker can saturate the connection to a target victim. It means all the connection to the victim would be bottlenecked and passed through attacker nodes so that it can manipulate the connections. Following eclipse attack scenarios are captured by our model:
No Eclipse Attack: This study model captures this case.

Isolate the Victim: This captures those cases where total mining power decreases. In return, it increases the fraction of mining power possessed by an adversary.

Exploit the eclipsed victim: Adversary uses victims mining power to expand its own chain.

3.3 Selfish Mining MDP:
As discussed previously the main goal of a selfish miner is to increase the relative number of adversary block in the main chain. In this study, the model author has captured that by optimizing the relative revenue. But there is a problem of applying single player MDP in this particular case because selfish miner deals with relative revenue. To overcome this problem the author has applied Sapirshtein el. Sapirshtein el proposes that an adversary with less than 33% of total hash power can make a profit from the network. This model captures various parameter such as block propagation time, block generation interval, block size and eclipse attack.

3.3.1 Optimal Strategies For Selfish Mining :
Authors have used MDP solver for finite state space MDP’s. The output author received from the model is below. Here the author tries to find the impact of stale block rate on selfish mining.

Figure 8: Selfish mining (Relative revenue vs Adversarial mining power)
** Pictures taken from ETH Zurich Research Report.

In Figure 8 author tries to understand how adversarial mining power influences the relative revenue of an attacker. For this he has put the adversarial mining power is in X-axis and relative revenue in the Y axis. The graph is drawn for a stale block rate of 1% and 10%. It is seen from this diagram that relative revenue increase with the increase of adversarial mining power. An upper bound is also taken in this diagram to understand the cases when the relative revenue of a selfish miner maximized by overriding a block of an honest chain. Figure 8 shows the upper bound exceeded when network delays and parameters are captured.

Figure 9: Relative revenue vs Stale rate
** Pictures taken from ETH Zurich Research Report.

In Figure 9 author tries to understand the relationship between stale block rate and relative revenue. He compares relative revenue in Y axis with stale block rate in X-axis for a mining power ? of .1 and .3 respectively. This diagram suggests a nonlinear relationship between relative revenue and stale block rate.

Author has also studied the impact of the eclipse attack in selfish mining. Figure 9 explains the relationship between eclipsed mining power ? and adversarial mining power ?. In this study the cases considered are
1. where adversary uses victims mining power ?
2. When an adversary uses honest miners blocks to advance its own chain.

It is seen for higher ? values selfish mining capability also increases. In this graph, an exceptional case is also observed for ?=.3 and ?=.38. For this situation, it is more profitable for an adversary not to include some of the victim’s blocks. Here victim’s blocks are accounted as a reward for the honest chain. This, in turn, reduces the block share of an adversary.

Figure 10: Eclipsed mining power vs Adversarial mining power
** Pictures taken from ETH Zurich Research Report.

3.4 Double Spending MDP: As discussed earlier in the double-spending rational adversary tries to maximize its profit. In double spending, it is assumed that loss in operational cost is less because the adversary can earn some goods or money in exchange for a transaction. In double spending, exit state can only be reached if the length of an adversarial chain is at least a block longer than the honest chain (la ; lh ) after k block confirmation for an honest chain with 1?? mining power. This is described in the below table 2. A question can arise during this study as the adversary is rational it is hard to reach an exit state. But it is found that in exit state adversary can earn a reward of

blocks.

** Pictures taken from ETH Zurich Research Report.

3.4.1 Optimal Strategies for Double Spending: To create optimal strategies author has used the pymdtoolbox library and applied PolicyIteration algorithm. By this block confirmation value, k is received which is sufficient to make a safe transaction in presence of rational adversary in the network. To decide in a certain scenario if a rational adversary would do double spend or selfish mining, a minimum value of double spend vd must be determined. For achieving that author start with high double spending value so that exit state is reachable in optimal double spending strategy. Author has done this because the presence of exit state in policy ensures high profitability for doubles spending strategy and the other cases honest mining is more profitable. In this below Table -3 an example is shown for optimal strategy.

Table 3: Optimal Strategies for double spending.

** Pictures taken from ETH Zurich Research Report.

Here ? = 0.3,? = 0,rs = 0.41%,cm = ?,? = 0 and vd = 19.5. Length of adversary chain is la, taken as rows. Length of honest chain is lh. Three values of each entry are irrelevant, relevant and active. * means unreachable and w, a, e represents wait, adopt and exit respectively. In this example cut off value for honest chain and adversarial is taken as 20. This suggests both this chain length cannot be greater than the defined cut-off value. So what is the main goal of this analysis? The attacker must exceed a threshold if it successfully wants to double spend for a fixed number of block confirmation k. Otherwise, honest mining is more profitable. This result is illustrated in Figure 10. The x-axis shows how the adversarial mining power is influencing the threshold. Change in the values of k (the number of block confirmations) lead to different curves.

The y-axis in Figure 10 shows how many successive blocks are needed to be mined before a double spending attack to be successful. For an adversary, around 30% mining power needs 6 block confirmation and the “expected number of blocks” is around 100.

An adversary with mining power of more than .25 needed less than 1000 blocks to successfully carry out double-spending attack.

Figure:10 Expected blocks for double spending rs = 0.41%, ? = 0, cm = ? and ? = 0.

** Pictures taken from ETH Zurich Research Report.

Here stale block rate is represented by rs. ?, cm represents the propagation parameter and maximum mining costs respectively.

Impact of Propagation Parameter: Propagation parameter signifies the connectivity efficiency in an adversarial chain. It suggests if connectivity increases in the adversarial network then adversarial mining power also increases. Author has put adversarial mining power in the X-axis and shown double spending transaction should have a threshold value. If transaction value is more than the threshold value, then only double spending is profitable. It can also be seen from Figure 11 that higher the propagation parameter ? lower the transaction value an adversary expects to double spend.

Figure:11 Impact of propagation parameter ? with respect to double spending transaction value.

** Pictures taken from ETH Zurich Research Report.

In this graph double spending value(vd) is taken in Y-axis and adversarial mining power(?) in the X-axis. If ? increase vd decreases.

Impact of mining costs: From the study, it is found that mining cost has a negligible impact on adversarial strategy. It is shown by the below Figure 12.

Figure 12: Impact of mining cost.

** Pictures taken from ETH Zurich Research Report.

Value of double spend (Vd) is in the Y-axis and adversarial mining power(?) in the X-axis. rs = 0.41%, ? = 0, ? = 0 Cm represents maximum mining cost ?vd is the difference in costs.

Impact of Stale Block Rate: In Figure 13 impact of stale block rate is explained for double spending. This below experiment is carried out for a mining power of .1 and .3 respectively. It can be seen if stale block rate grows the value of double spend decreases. Author has found double spending value of an adversary decreases from 9.2 to 6.4 block reward with mining power .3 and a stale block rate of 10% and 20 %.

Figure:13 Impact of stale block rate.

** Pictures taken from ETH Zurich Research Report.

Here Vd is the value of double spend in the Y-axis, Stale block rate in X-axis and adversarial mining power is represented by ?.

Impact of Eclipse Attack: The impact of eclipse attack is represented by Figure 14. It is assumed that an adversary attacks an honest block with ? eclipsed mining power. It can be observed eclipsed mining power increases with the increase of adversarial mining power. So eclipse attack is beneficial for an adversary. For example, an adversary with an adversary with ?=.025 and ? =.1 reduces the double spending value (vd) from 880 block reward to .75 block.

Figure 14: Full eclipse attack
** Pictures taken from ETH Zurich Research Report.

In Figure 14 eclipse mining power ? is in Y axis and adversarial mining power is in X axis and , rs = 0.41%, ? = 0 and cm = 0.

Bitcoin vs Ethereum: Figure 15 shows the reward required for a double spending attack to make a profit. The y-axes show the reward required from fraudulent behavior as multiples of the block reward, i.e. multiples of the reward of non-fraudulent behavior.
The figure also contrasts between Ethereum and Bitcoin. As a consensus algorithm both this chain uses proof of work, but the key difference is the block time. i.e. the time duration between two blocks generation. Stale block rate increases because of shorter block times. It means the time gap between finding two blocks is much shorter in Ethereum. Thus, participant blocks more often return finding the same block which increases the stale block rate in the network.

Below points are observed by the author in the study.
First: Figure 15 shows 6 Bitcoin block confirmation is more resilient to double spending than that of 12 Ethereum block.

Second: Ethereum’s double spending resilience is better only for an adversary with less than 11% hash power.

Third: If block reward goes up blockchain is more resilient to double spending attack.

Figure 15: Double spending resistance of Ethereum vs Bitcoin
** Pictures taken from ETH Zurich Research Report.

Block reward is in the Y-axis and Adversarial mining power in the X-axis. Ethereum (k ?{6,12}) vs. Bitcoin (k = 6).

Author has also tried to compare both this block chains by equalling their stale block rate. It is observed that Ethereum’s security is lower in caparison to bitcoin Figure 16 explains the following.

Figure 16: Comparison between Ethereum and Bitcoin.

** Pictures taken from ETH Zurich Research Report.

Value of double spend is on the Y-axis and Adversarial mining power is in the X-axis. Here k is 6, rs = 6.8% and their difference is ?vd.

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3.11 Explain the role of the init process on UNIX and Linux systems in regard to process termination.
Based on the relationship between a parent and child process, if a parent did not invoke wait() and simply terminated (making child process an orphan), UNIX and Linux Systems assign them as the init process. This process periodically invokes wait(), where it will continue until these orphans finish their final statement before exiting using exit().
3.12 Including the initial parent process, how many processes are created by the program shown in Figure 3.32?
8 processes are created by the program
3.14 Using the program in Figure 3.34, identify the values of pid at lines A, B, C, and D. (Assume that the actual pids of the parent and child are 2600 and 2603, respectively.)
Line A: 0
Line B: 2603
Line C: 2603
Line D: 2600
3.17 Using the program shown in Figure 3.35, explain what the output will be at lines X and Y.
Line X: CHILD: 0 CHILD: -1 CHILD: -4 CHILD: -9 CHILD: -16
Line Y: PARENT: 0 PARENT: 1 PARENT: 2 PARENT: 3 PARENT: 4

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3. Origin of the research problem 4. Review of Research and development in the Subject 4.1 National Status Endotoxin content of PM10 and its association with inflammatory activity, air pollutants and different meteorological conditions were investigated by Mahapatra et al. (2018). The mean concentration of endotoxin was found to be in the range of 0.29-0.53 EU/m3. Though positive correlation between endotoxin concentration and presence of pollutants were found in present study but inflammatory activity exhibited negative correlation with endotoxin content associated with PM10. Air quality of temple in city of Mumbai was examined by Mehta et al., (2015) in terms of microbiological load. Significant microbial concentration was found due to improper ventilation. Gangamma. (2014) characterized the airborne bacteria in ambient environment of Mumbai city. In addition, elucidation on the role of bacterial endotoxin in PM induced inflammatory responses in vivo has also been investigated by them. Total 28 species belonging to 17 genra were identified and amongst them, significant domination of Gram positive and spore forming group of bacteria were found in Mumbai city. Joshi and Srivastava, (2013) identified the microbes and fungi in indoor air of rural residential houses. Sequence obtained from PCR amplification was analyzed and confirmed the presence of bacterial species such as Arthrobacter SP. FB24 and Bacillus Cereus and fungal spores like Aspergillums cravats. Abundance and characterization of culturable bioaerosol at Delhi, India were investigated by Kumar et al. (2013). The average concentration of airborne bacteria in Delhi varied from 0.43 – 3.35×107 CFU/m3 which is relatively higher than the range reported from temperate regions. Their findings suggested the strong correlation between meteorological parameters (temperature, humidity) and abundance of microbial load at the sampling site. Shape and size controlled antimicrobial AgNPs were synthesized using Aloe-vera plant extract by Logaranjan et al. (2016). Shape, size and structural properties of synthesized nanoparticles were investigated by different characterization techniques like SEM, FTIR, XRD. Significant antimicrobial activity of AGNPs were found against both gram positive and gram negative bacteria. A simple one-pot green synthesis of stable AgNPs usingA.indicaleaf extract at room temperature was reported by Ahmed et al. (2016). The synthesized silver nanoparticles showed efficient antimicrobial activities against both E. coli and S. aureus. According to their findings only 15min were required for the conversion of silver ions into silver nanoparticles at room temperature, without the involvement of any hazardous chemical. Parwar et al. (2016) developed Sericin/PVA/Clay Nanofiber mats by Electrospinning method for antimicrobial air filtration mask. Along with structural, mechanical and antimicrobial activity, PM absorbing capacity of these synthesized mats were also examined and their results showed a promising capacity of this mat as an air filtration mask. 4.2 International Status Airborne particles in indoor environment in terms of biological components were assessed by Mirhoseini et al. (2016). Average concentration of airborne bacteria and fungi were found to be 163 and 151 CFU/m3 respectively. In this study, predominant bacteria were found to be staphylococcus SP. and Arthrobacter SP. Seo et al., (2015) investigated the concentrations of (1, 3)-b-Glucan in submicron fungal fragments, airborne mold and bacteria, and PM10 in both indoors and outdoors environments of schools. Their findings confirmed the comparable amounts of submicron fungal fragments in school. Metagenomic methods were employed by Cao et al. (2014) to analyze the microbial composition of Beijings PM pollutants. Their findings suggested that the majority of inhalable microorganisms were soil associated and nonpathogenic to human. Size segregated PM (UFP, FP and coarse) particles were collected from the peat fire by Kim et al. (2014) and analyzed them for the chemical constituents and endotoxins content. Highest endotoxins content was found in the coarse particles which elicited the greatest pro-inflammatory responses. Lin et al. (2014) synthesized PVA nanofiber mat doped with aligned AgNPs using green manner. According to their findings the prepared nanofiber mat is suitable for broad range of application starting from antimicrobial agent to water and air purification techniques. Controllable AgNPs were developed by Chandra Sekhar et al. (2016) using extracts of Limonia acidissima tree. Various phyto-chemical compounds (saponins, phenolic compounds and amines) present in natural plant extract act as a reductant and produced AgNPs easily. Kinetic study in formation of AgNPs was verified in this study by UV-Vis technique. Antibacterial activity of produced AgNPs was investigated against Escherichia Coli and Bacillus Subtilis and their results suggested the excellent antimicrobial activity of AgNPs against both of them. Min et al. (2018) has been reported efficient eco-friendly multifunctional silk-protein nano-fiber air purification filter which is effective for reducing air pollution and thus capable of protecting the environment. Their results confirmed the excellent filtration efficiency (90) of prepared air filter which exceeded even the performance of the high efficiency particulate air (HEPA) filters. Chlcone penetrated antibacterial air filter (CPF) for inactivation of bioaerosol was developed by Huang et al (2018). Their results suggested that the survival of bioaerosol depends on the concentration of CPF. This study also suggested the inactivation of captured bacteria in presence of Chlcone and in addition, higher antiseptic effect of the penetrated was found for gram negative bacteria as compared to gram positive bacteria. Successful formation of Chitosan (CS)/ PVA nano-fiber and their application in air filtration technologies were done by Shalihah et al. (2017). Morphology and structural properties of the developed fibers were examined by SEM, FTIR and XRD respectively. Synthesized fibers exhibited significant filtration efficiency and post filtration various properties of the fibers such as morphology and porosity were also investigated. Kang et al. (2016) developed a high throughput fabrication process for antimicrobial filter with eminent antimicrobial efficiency using electro-spraying and nebulization method. Their results suggested a directly proportional relationship between the amount of antimicrobial substances coated on the filter and their filtration performance. Chen et al. (2016) made AgNPs/NSP modified air filter and assessed the filtration efficiency and antimicrobial efficacy of the synthesized filter. Antimicrobial effects of the prepared air filters were evaluated against the bioaerosol including Escherichia Coli and Candida famata in testing chambers under different relative humidity conditions. AgNP/NSP filter exhibited 91 and 95 efficacy against C. famata and E.coli. Their findings suggested that this modified air filter can be applied to air cleaning purpose and would be very effective in removing bioaerosol and thus would be capable of protecting human health in indoor environment. Chitosan nano fiber electro spun with Polyethylene oxide (PEO) and AgNO3 was successfully developed by Annur et al. (2015). FTIR and XPS both techniques were used to characterize the surface of the prepared nano fiber. Antibacterial activity of this nano fiber was also evaluated by measuring zone of inhibition against E. coli. Hwang et al. (2015) fabricated antimicrobial air filter from Natural Euscapnis Japonic nano-particles. Evaluations of antimicrobial activity, cytotoxicity of coated filters were performed in this study. In addition, filtration efficiency of synthesized filters was also checked. According to their results the hybrid fibers exhibited tremendous antibacterial activity against both gram positive (99) and gram negative (97) bacteria. Excellent Cooper and their research group (2013) introduced antibacterial filter made up of Chitosan- Poly-caprolactone utilizing the natural antibacterial propertied of CS. They have found that incorporation of 25 CS into nano fibers membrane reduced S. aurous bacterial colonization. They have also demonstrated the ability of fibers to remove particles and act as a pre-filter. Electro spun of PVA CS oligosaccharide with Ag nanoparticles was done by Li et al., (2013) to produce fiber mat.. Bio compatibility (antibacterial activity) of nano fiber was evaluated and showed significant inhibition in growth of E. Coli and Staphylococcus. 5. Significance of the study Microorganisms associated with airborne particles is a significant toxic component responsible for serious public health concern and analysis of these PM bound microbes will provide interesting data, not only for the evaluation of its impact on human health and environment, but also for the identification of specific emission sources. Therefore, characterization of airborne microbes and its toxicity evaluation is of paramount importance. At the same time, alleviation of these microbes is also necessitated in order to address the health concerns. Mitigating the environmental contaminants with the help of nano-based approaches has been developed already but most of the researches are based on aquatic environment. However, researches on alleviation of PM bound microbes by the green synthesized nanofiber air filter are still untouched. So methodical research is necessitated in order to understand the role nano-fiber air filter in capturing the PM bound microbes. This proposed work will provide a sort of base, for evaluating the quality of air and health risk associated with it and will thus be helpful for the society, policy makers and environmentalist for proper planning and mitigation measures. 6. Objectives Indoor particulate pollution is acknowledged as an important public health concern accountable for broad range of adverse health effects and these adverse health effects associated with PM are attributed to biological constitutes (micro-organisms) present in it. Therefore, detail evaluation of the toxicological profiles of PM bound microbes (their concentration, trends, and toxicity assessment) is foremost important to measure the control strategies for regional as well as global air pollution. At the same time inactivation of these airborne microbes by natural polymer based air filter is also necessitated for protection of human health in indoor environment. Thus, in the lieu of this, the objectives of present study are 1) Characterization and toxicological evaluation of indoor PM in terms of its microbial components 2) Green synthesis and characterization of AgNPs from natural plant extract 3) Preparation, characterization and antimicrobial activity of CS-PVA-AgNPs nano-fibers 4) Determination of the filtration efficiency of the prepared nano-fibers 7. Methodology 7.1. Sample collection and extraction 7.2. Characterization and identification of PM bound microbes and its toxicity assessment 1 ml of PM extract will be transferred from the suspension on duplicate plates containing selective culture medium (Nutrient agar, Eosine Methylene Blue Agar and Blood Agar for bacteria culture and Potato Dextrose Agar and Malt Extract Agar for fungal culture) directly which further will be incubated at 37C for 72 h under aerobic conditions. Finally, airborne concentrations of aerobic microorganisms will be determined by calculating colony forming units (CFU). The colonies counted on each sample type will be used to identify the constituent species (genus). Counted colonies will be first categorized based on their morphological and color characteristics. Most abundant colonies will be transferred to new plates for purification and identification by a PCR procedure at a certified laboratory. Toxicological profile of microbes will be determined in terms of endotoxins measurement by Limulus Amebocyte Lysate (LAL) method. PM extracted sample will be mixed with LAL reagent and incubated at 37C for 15 minutes followed by addition of substrate solution. Presence of endotoxins will be confirmed by developing yellow colour and then mixture will be measured spectrophotometrically at 405-410 nm. Finally concentration of endotoxins will be calculated from the standard curve. 7.3. Green Synthesis of AgNPs AgNPs will be synthesized from natural plant extract and reduction of Ag ions to Ag0 nanoparticles will be done in a medium of plant extract in which no extra reducing agent will be further used. Different phytochemical compounds present in plant extract will act as a reductant to produce AgNPs. Fresh and healthy leaves of natural plants will be collected locally and rinsed thoroughly with tap water followed by doubled distilled water. Afterwards, plant leaves will be boiled in 100 ml distilled water for 20 minutes and further cooled, centrifuged and filtered. Post preparation of leaf extract, 10 ml of 0.3M AgNO3 will be added to 10 ml of extract and will be incubated in dark overnight. Complete reduction of Ag to Ag0 will be confirmed by colour change from colourless to brownish yellow. Finally, the colloidal mixture will be filtered and oven dried. 7.4. Preparation and characterization of CS-PVA-AgNPs Nanofiber by Electrospinning 7.5. Antibacterial activity of prepared nano-fiber Antibacterial activity of prepared will be measured against both gram positive and gram negative bacteria by disc-diffusion method. Disc shape sample of nanofiber with 11 cm2 will be will be sterilized first with UV for 2 hr at 37C and subsequently placed on 24 hr old nutrient culture of PM induced bacteria and fungi. Finally the relative antibacterial effect will be found by measuring the diameter of the clear zone of inhibition formed around the disc as compared to the control. 7.6. Air permeability measurement Filtration efficiency of synthesized Nanofiber mat can be measured in terms of air permeability of the fabrics. The air permeability values of CS-PVA-AgNPs nano-fiber mats will be measured using air permeability testing instrument. The measurement will be carried out according to the ASTM D737-04 standard test method for air permeability of textile fabrics. Y, dXiJ(x(I_TS1EZBmU/xYy5g/GMGeD3Vqq8K)fw9
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3

3.Mrs. Robinson, you are trying to seduce me,” says Benjamin Braddock (Dustin Hoffman). The Graduate, directed by Mike Nichols in 1967 is an influential satire/comedy film about a recent East Coast college graduated who finds himself alienated and aimless in the changing, social and sexual general public of the 1960s, and questioning the values of society. The theme of the film is of an innocent and confused youth who is exploited, mis-directed, seduced (literally and figuratively) and betrayed by a corrupt, self-indulgent, and discredited older generation (that finds stability in “plastics”) that I found to be quite clear and understanding, while also capturing the real spirit of the times and allows America’s youth to perceive onscreen an image of themselves which they can both identify with and emulate. The Graduate is a significant film even today due to its use of abstract camera angles, telephoto lenses, excellent cinematography, and great acting. Few visual effects were used, however, matting and numerous point of view shots were used. These characteristics and the fabulous use of mis-en-scene, great writing and the era of the film all made The Graduate what it is today, magnificent.
Benjamin Braddock is at a crossroads in his life. He has just graduated college which means he has reached adulthood and must decide what to do with his life. The problem is Benjamin is too immature to handle it. He is passive and watches the world around him move on. Ben prefers to lie around in his parent’s pool rather than consider graduate school or finding good quality job. He is beginning to realize that the path his parents have chosen for him isn’t the one he wishes to follow. He is lost young man in search of high dreams, self discovery, and is frightened by the thought of becoming a man.
The film opens up with a close-up, disembodied image of Benjamin Braddock’s face (Dustin Hoffman) a twenty year old recent East Coast college graduate. He appears alone and isolated – he is – but when the camera pulls back, it reveals that he is on a plane filled with other passengers of all different ages. He is returning home to Los Angeles from college in the East. He appears slightly shy and uninviting; his face is blank, expressionless, lethargic, and almost zombie-like looking. The beginning and end of the film are very similar with each other – the young couple, is surrounded by a busload of passengers, but still remain isolated and unemotional. Benjamin stands mute to himself on the automated, moving walkway at the busy LAX airport the camera is positioned to reveal Ben’s left profile while the frame height is a medium close shot allowing Ben’s image to dilute in the viewers mind. In this profile shot, the character is positioned to the right third of the frame to allow sufficient space in front of Ben. This is done in order to not cluster the characters line of sight as seen by the viewer. Dustin Hoffman’s character appears to be lost, confused, and in the midst of discovering his life. The soundtrack also plays an important role in this interpretation. The song “Sounds of Silence” by Simon and Garfunkle establishes a feeling of sadness; it’s a non digital sound that expresses a melancholy reaction, it also reinforces the theme of his emptiness and alienation from his surroundings. As Benjamin is passively being transported across the airport to his luggage, the camera switches to Ben’s blue suitcase to reveal another instance of how passive the character appears to be. There is a prop, specifically a sign displayed in the scene that is viewed as the camera pans left to right. The sign asks “Do they match?” Implying does Ben and his suitcase match, this is a deliberate prop that initiates the viewers mind to contemplate how Ben and the suitcase are both passive. This motif of being passive is expressing the idea that Benjamin is a reactive young man who does what he is told. He is not brave, bold, or proactive; he is a puppet of his environment. Benjamin is in the stage of his life where he is searching for his future, and beginning to mature into a man.
As the film develops the underlying theme begins to change as Dustin Hoffman’s characters metamorphoses into a proactive character. Although, Bens passiveness is still quite present in the next scene at his parents Southern California home. From the opening scenes you can see how tight Ben’s parents hold is on him by the claustrophobic camera shots at his graduation party. Most of the scene is filmed with hand held shots giving the feeling of uneasiness. By not using a stedicam the viewer can relate with Benjamin’s nervousness, and desire to escape the chaos. The lighting is very low key which adds to the diluted image of Ben’s feelings. Everyone at the party is a friend of Ben’s parents who apparently makes them a friend of his, but he barely knows them past their last name and occupation. Ben is bombarded by guests, yet, shows no irritation, instead acts polite and passive. As the plot continues, Ben is seen to evolve into a more proactive character after entering the relationship with Mrs. Robinson.
One scene in particular that represents the underlying theme of becoming of age, and becoming proactive, is the first seduction scene between Ben and Mrs. Robinson. The mis-en-scene plays a key role in the theme of this scene at the Robinsons. The mis-en-scene of the scene is very complex and thought out by the director. The setting is very upscale, rich, and elegant. Ben is wearing a blue suit with a yellow and blue striped tie. The colors blue and yellow are common motifs in the film, yellow representing youth and blue representing maturity. Ben’s suit represents a crossroad of the two. The high contrast lighting is also a factor that represents Ben’s inner conflict of not wanting to become a man. The lighting is used as a means of shadowing Ben’s face to only partially reveal his emotions. The abstract shadowing of the character’s face shows confusion, for there is still an unknown factor concealed behind Ben’s emotions. The other character present in the two shot is Mrs. Robinson; she is an elegant, sophisticated women searching for her own lost youth. Her dominance is very noticeable through her costumes. Her dresses were very erotic, for throughout the movie Mrs. Robinson is seen in an array of dresses all resembling some sort of animal skin. These costumes emphasize the idea that Mrs. Robinson is predator stalking her prey. The background in the bar at the Robinsons is a luscious botanical garden; this garden seems to represent a jungle for the predator and the prey. The power of the characters is also present in the note that Mrs. Robinson’s eyesight is looking down at Ben. This displays a sense of power, dominance over Ben expressing Mrs. Robinson’s confidence and control. These eye level shots are crucial in the analysis of which character is dominant. The scene is filmed in wide angle arrangement, with a deep focus lens in certain situations. One shot that is classic in the scene is the low angle shot of Benjamin through Mrs. Robinson’s legs. The shot presents the seduction occurring from Mrs. Robinsons and her domineering use of teasing the protagonist. The rack focus is also evident in the scene; these transitions from a shallow to deep focus add to the watery image of the characters identities. There’s an abundance of wide focus shots with numerous occurrences of medium close ups that show the characters emotions, while making the viewer seem more intimate. With deep focus lenses being used the scene appears to be more realistic and relatable compared to when it’s unfocused and diluted.
This scene incorporates Ben’s passiveness once more by emphasizing on Ben’s lack of control and will to stand up for himself. Mrs. Robinson states “Drink” as she forces the bourbon onto Ben after he deliberately said no. This scene supports the theme of self discovering; by initiating the underlying theme of Mrs. Robinson’s substantial control over Ben. Without making Ben’s lack of control obvious it wouldn’t be evident that his character would transform into a proactive man. Another scene that supports the theme of self discovery is the scene after Ben takes out Mrs. Robinson’s daughter Elaine. In the beginning of the scene Mrs. Robinson runs through the rain and enters Ben’s car, she then orders him to drive around the block. At this point in time Ben is still a reactive character who has numerous indecisions. He does as he is told and drives until Mrs. Robinsons threatens to reveal their affair to Elaine. This news troubled Ben, for he recently discovered a new found love for Elaine. His love was based on companionship for the first time in his life. Ben was in control with Elaine, this control was another stepping stone into Ben’s eventual maturity. This scene is the midpoint in the act of the movie, for Ben goes from being a reactive character to a proactive character. This is evident as Ben exited the car and sprinted through the rain to Elaine’s side. Water being another common motif present in the film is very important in this scene. Water is a very symbolic element in the film that represents new life, becoming a man, and right of passage. By shooting Ben running through the rain with a telephoto lens it appeared Ben was not moving any closer to his goal. This effect added to the theme of transitioning into a man by emphasizing that he was now proactive. A continuity error that I found present in the scene of Ben running through the rain was that there was sunshine on the grass in the background as it poured down rain. It was evident that the rain was simply generated in this suburban Southern California community.
The lighting in the scene was very natural; there were no shadows or abstract lighting focusing on the characters. This scene is one of the most crucial scenes in the movie, for it represents Ben’s first transition into adulthood. This conflict pertaining to Mrs. Robinson revealing the affair and the numerous other obstacles that appear through out the movie try to prevent Ben, the protagonist from his goals. However, he eventually overcomes these obstacles and finds his identity.
The last scene that really relates to the theme of the movie is the concluding scene. After driving to UC Berkeley, Ben finds Elaine and makes amends for his wrong doing. Although, the amends were made with Elaine, Ben ran into a new problem, Mr. Robinson. This “Darkest Hour” occurred after the news of the affair with Mrs. Robinson had been revealed. Now Mr. Robinson stood between Ben and his goal of winning Elaine’s heart. After a quarrel with Mr. Robinson, Ben heard the news of Elaine’s marriage. This obstacle, including not knowing the location of the wedding, running out of gas, and the church being locked all slowed Ben’s progress.
The scene transitions from Ben’s car running out of gas to Benjamin running to the church; the shot is done using a telephoto lens. This lens is used to portray an image from far away to close. The effect makes the shot appear that Benjamin is not moving. This long shot displayed Benjamin’s final pursuit of his goal; it represents his proactive personality to seek the future. In the scene Benjamin went from wearing blue suits to casual clothing, demonstrating his change of character. Another significant piece of mis-en-scene is Benjamin’s unshaven beard. The beard was a significant part of the theme of the movie. The beard represents age, maturity, manhood, whereas in the early part of the movie Ben was constantly shaving to rid this stage of becoming a man. Benjamin obviously is confused and wants to remain young, a kid without responsibilities and work.
The final scene demonstrates Ben’s will to take action and pursue his goals. The setting, Santa Barbara, was a surreal environment that added to the effect of an upscale warm Southern California community. The crucial shot of the scene was magnificent; it was shot from the floor of the church with a tilted angle camera portraying Ben almost a biblical figure reigning over the families. This scene finalized Ben’s transition into man hood and Elaine’s relationship with her mother. The two characters exited the church in chaos and randomly enter a yellow school bus. The bus represented their exit and proclamation to pursue there goals. This bus is representing their confused perception of the future, for they are still uncertain of their lives. The scene is shot using a deep focus lens; the deep focus creates a perception of real life. The camera is stationed to view a medium close up shot of the Elaine and Ben to show there emotions dwindle. First the two characters were excited with the spontaneous decision, however, Mike Nichols shot the scene so the characters emotions were present after there adrenaline ceased. The characters faces turn into a ghostly, serious expressionistic manner. This shot expresses the idea that they were regretting their decision or they knew they were off to an unknown future. This scene finalized the theme of the story; it now portrayed Benjamin as man who is proactive. He is neither indecisive nor impotent now that he has faced his conflicts and found resolutions.
The Graduate is a cult classic. Not only was it a movie for the generation of baby-boomers in the Sixties, but it still remains a symbol of the teenagers today that are searching for something and those that are “a little unsure about their future”. Benjamin Braddock, a college graduate comes home only to be seduced by his father’s business partner’s wife. He then falls in love with her daughter, Elaine, which in turn leads to a rollercoaster of events which end up leading to the final scene of Benjamin taking Elaine away after getting married to another man. This film is a classic example of coming of age; Benjamin is boy in the beginning, and a man at the end. Without the direction of Mike Nichols, acting by Dustin Hoffman and great cinematography this film would have been forgotten and ill represented.

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