Gunshot Forensic Analysis

Gunshot Forensic Analysis School of Chemistry MM4EOX: Electron-optical and X-ray Techniques Pages 12: Forensic investigation: trace evidence analysis for gun-shot residue Page 3: Phase identification : characterization of nanostructured materials Page 4: Enviromental safety: characterization of fine scale particle distribution Forensic investigation: trace evidence analysis for gun-shot residue Introduction The ability to identify gunshot residue has provided solution to the problems encountered in the resolution of forensic science, legal medicines, and for shooting distance determination. Visually comparing the casework powder residue pattern on the garment or on the skin of the victim with the pattern obtained from a series of test firings at known distances, using the same gun and ammunition has been used as a method for routinely estimating gunshot range. Burned and unburned powder grains, carbonaceous particles, bullet jacket debris, shaving and dirt have been shown to be examples of materials ejected from the bore of the weapon around the entrance hole of the bullet and have been used as materials for analytical determination in order to obtain a more and accurate result.1 An issue that has become very important in criminal investigation is trace evidence. Very often it come into place after the commission of a crime, well after the charges have been filed and well after the completion of forensic examination. Trace evidence can usually take the form of fibers, paint chips, soil, building materials, glass, gunshot residue, seeds, feathers, animal hair, human hair, wood fragments and other material. It has been proved that these substances are usually transferred between individuals during physical contacts and can also be transferred from individuals to environments and from environment to individuals.2 This report shows how complementary analytical techniques ranging from batch injection analysis (BIA) method, based on differential pulse anodic stripping voltammetry (DPASV), scanning electron microscopy/ energy dispersive X-ray analysis (SEM/EDX), capillary electrophoresis, can been used to identify trace evidence for gun-shot residue. Batch Injection Analysis Batch injection analysis (BIA) method, based on differential pulse anodic stripping voltammetry (DPASV) can been use to carry out forensic analysis of lead in gunshot residues (GSR). The design consist of a simple â€Å"J† shaped adaptor which is being used to direct the flux of the analyte injected with a micropipettor onto the hanging mercury drop electrode of any commercial electrode stand. Lifting with adhesive tape is usually selected for field use and pasting of the tape is done on polyethylene screens and stored in capped vials. Sampling is usually done with multiple strips and thus provides coarse mapping of the distribution of the Lead on the shooters hand following the dissolution/extraction step with chloroform/aqueous HCl. Certain volume of this aqueous phase is then injected for few seconds for accumulation of the Lead on the HMDE at a certain volt (vs. Ag/AgCl). A detection limit of 20 ng/mL of Pb(II), outreaching for GSR analysis can be achieved without oxygen r emoval, at a frequency of 20 injections per hour. Quantitative analysis has shown the detection of over 90% of lead residues.3 Scanning electron microscopy/ energy dispersive X-ray analysis Elemental analysis using SEM/EDX can be carried out in order to understand bullet structure and major elemental composition. Datas produced from elemental composition of bullets can be used in deciding the exact methods most appropriate for the identification of bullet hole and the determination of firing distance. Bullets and shots are usually collected from unfired cartridges and subsequently brushed with detergents and cleaned using tap water, distilled water, and acetone. Double-sided carbon tape can be used as a means of mounting jackets, lead cores and lead bullets and shot onto the sample stub on subjection to SEM/EDX analysis. The external surface, cross section of lead core, lead bullet, or lead shot can be subjected to elemental analysis using EDX. The internal surface and cross section of the jacket can also be subjected to elemental analysis in order to understand its structural composition. EDX measurement conditions can be set from the SEM unit with regards to spectral measurement, multi-point measurement, mapping, and display of analysed elements on the SEM monitor. The image data obtained from the SEM can be used as basic data for the EDX, while the setting conditions for the SEM units are automatically transferred to the EDX unit. The function which provides the strongest backup for elemental distribution is the Smart Map. The Smart Map operates by recording the X-ray spectral data for all analysis points on the test sample together with the positions of analysis, thus providing the user to recall valuable data as needed. Backscattered electron imaging mode in SEM is able to reveal layers of metals on the jackets cross-section and its subsequent compositions while on the other hand, EDX analysis is able to reveal the coating elements detected on the external surface of lead bullet.4-5 At the moment, this technique is widely accepted due to the morphological (SEM) and elemental (EDX) determination of the metal residue. Capillary electrophoresis Capillary electrophoresis can be used for the analysis of organic and inorganic components of gunshot residue in order to study sampling methodology, selectivity, reproducibility, quantification and the enhancement of the bulk analysis. A typical P/ACE MDQ Beckman capillary electrophoresis system is being used with polymide bare fused silica capillaries. A diode detector is usually used as a means of carrying out direct UV detection. A temperature of 25oC, with a positive voltage of 30KV and hydrodynamic injection of 5s and 0.5 p.s.i is usually used. The conditioning of new capillaries is usually done by rinsing with ethanol, HCL, NaOH at specific time and temperature. Between runs, the capillary is usually rinsed with deionised water, NaOH, and again with deionised water and background electrolyte at specific times. The sample is usually ejected into the capillary by temporal replacement of one of the buffer reservoir (usually at the anode) with a sample reservoir upon application o f either an electric potential or external pressure for a few seconds. Upon replacement of the buffer reservoir, an electric potential is applied between the capillary and the separation is performed. Optical UV-detection of the separated GSR component can be obtained directly through the capillary wall near the opposite end (usually near the cathode). Swabbing technique has been used as a means of obtaining samples from gunshot. This technique is however not too good in detecting important organic residue such as barium and antimony. Figure 1, shows a typical zone of sampling for gunshot residue.6-7 Figure1 Typical zones of sampling for gunshot residue. (A) web and (B) palm.7 Phase identification: characterization of nanostructured materials Complementary analytical techniques such as X-ray diffraction (XRD), electron microscopies such as TEM SEM, and EDX spectrometry can be employed as a set of tools in characterizing a one-dimensional inorganic nanostructure in order to investigate the crystal structure, particle size distribution, morphology, composition and aggregate state. XRD The technique of XRD can be used to deduce the lattice parameter of inorganic nanostructures which can be used to provide information on the thermal properties of the material, strain state or an analysis of the defect structure. The diffraction pattern of the material can be indexed appropriately if the crystal structure of the material is known. For example, in a cubic system, the d spacing which correspond to each diffraction pattern is related to the lattice parameter a following the equation a2 = d2 / (h2 + k2 + l2) in which hkl are the miller indices. This is however used in indexing the diffraction pattern. This technique is however subject to systematic error in the position of the diffraction peaks and random error in the individual calculation of the lattice materials.8 The calculated lattice parameter value is usually compared with the experimental value and this can further be used for appropriate interpretation of result. SEM/EDX Nanostructured materials can be characterized by SEM integrated with an EDX analyzer in order to determine the particle morphology and chemical composition of the sample. The SEM column forms a focused probe of electrons on the sample while the beam current and probe current are usually adjusted as required. An image is formed by scanning the probe in a raster pattern on the sample, detecting some excited radiations from the sample, and storing the result either as a pattern of varying intensity levels on a cathode ray tube (CRT) screen or an a pattern of digital values in electronic memory for later manipulation and display. SEM images are usually formed by detecting either the secondary (low-energy) electrons emitted from the sample, or the backscattered (high-energy) electrons.9 Secondary electron images can provide information on the sample topography thus revealing information about the grain size distribution of the material. TEM/EDX TEM/EDX investigation of nanostructured materials can provide a more detailed information about the smallest particle. When the selection area diffraction (SAD) pattern is projected onto the viewing screen, we can use this pattern to perform the two most basic imaging operations in the TEM. In order to form an image in TEM, we either use the central spot, or we use some or all of the scattered electrons. The way we choose which electron forms the image is to insert an aperture into the back focal plane of the objective lens, thus blocking out most of the diffraction pattern except that which is visible through the aperture. If the direct beam is selected the resultant image is a bright-field (BF) image and if the scattered electrons are selected then the resultant image is the dark-field (DF) image.10 The dark-field imaging and digitization of particles can be used to extract size distribution of the grains through thresholding and measurement of the projected areas. Enviromental safety: characterization of fine scale particle distributions Appraisal of the fine scale particle distributions emitted from a waste disposal furnace can be carried out using SEM/EDX to investigate the particle morphology, composition and chemistry, while TEM/EDX can be carried out to give a more detailed information about the particle size distribution and SIMS to determine isotopic ratios. SEM/EDX SEM equipped with an energy dispersive X-ray (EDX) spectrometer can be used determine the elemental composition, morphology and chemistry of emitted particle in a waste disposal furnace. In order to determine the emitted particle containing the heavy metals, the sample is subjected to backscattered electron imaging while emitted particle containing salts can be imaged in the secondary electron mode. The detected backscattered electrons originate from the larger volume of the sample than do secondary electrons, and thus form an image of lower resolution. Focusing of a small spot on the high Z area followed by analysis of the X-ray signal with EDX allows the resulting X-ray lines to be detected and the elemental composition determined. TEM/EDX TEM images of the sample which comprises DF and BF can be coupled with EDX analysis and chemical mapping can be carried out. Both DF and BF imaging in TEM can be used to investigate the metal speciation in the fine fraction of the emitted particle furnace. DF imaging and digitization of the particle can be used to extract size distribution through thresholding and measurement of project areas. Elemental composition of the emitted particle could be detected in small aggregates upon analysis by EDX and selected area electron diffraction. SIMS Secondary ion mass spectrometry (SIMS) can be used to determine isotopic ratios of the heavy metals from within emitted particles. It operates by switching between masses and it possesses two microfocus ion sources. Sputtering is usually done with a primary O2+ and the intensity controlled by tuning the primary ion beam. The instrument can operate with a mass resolution power (MRP) of 25000.11 REFERENCES [1] Roberto G, Anna P and Salvatore, J Forensic Sci, March 2008, Vol. 53, No. 2. [2] Douglas D, Crime Scene, United States Attorneys Bulletin, 2001Vol. 49 No. 5. [3] Adriana D, Ivano G and R. Gutz, Electroanalysis 2005, 17, No. 2. [4] Hsien-Hui M, and Yen-Lin C, Forensic Science Journal 2006 5:21-34. [5] Toshikazu Y, Sukehiro I, Yoshinori N, Keith S, Readout, 2001 No. 22. [6] Richard A, Jennifer M, Harry E, Background theory and principles of capillary electrophoresis. [7] Ernesto B, Alma L. Revilla V,J. Chromatography A, 1061 (2004) 225-233

Epic Characteristics of Paradise Lost Essay -- essays papers

Epic Characteristics of Paradise Lost Paradise Lost is one of the finest examples of epic tradition in all of literature. In composing this work, John Milton was, for the most part, following in the manner of epic poets of past centuries. By knowing the background of epic characteristics and conventions, it is easy to trace their presence in Book I of Paradise Lost. One of the biggest questions that a reader must face is that of the hero; exactly who is the epic hero in the poem? While Satan may not be the "hero" of Paradise Lost, Milton quickly establishes him as its main character, and as the most complex and detailed of Milton's descriptions. Satan is given many traditional attributes as an epic hero. Although he may not be the classical hero, he does defeat the creatures that God had created. This is why I feel that Milton meant Satan to be the hero of Paradise Lost. Another three characteristics of the epic are hardly items of debate, as was the hero. The setting of the poem is indeed vast in scope. It ranged from Heaven to Hell and to the Earth. The action of the story also consisted of deeds of great valor that required superhuman courage. Although biblically, we may not consider Satan to have courage, we know that he must have shown it while fighting the war in heaven against God. According to the dictionary, courage is "that quality of mind which shows itself in facing danger without fear or shrinking." Satan most certainly may be said to fit this description. There were also supernatural forces at work throughout the poem, such as gods, angels, and demons. In addition to these four epic characteristics, Milton also employees the so-called epic conventions in his poem. Milton definitely begins b... ...the hive†¦" (lines768+). These similes are Milton's way of helping us to better relate the story to common things in our lives. In spite of some alterations and modifications, we can clearly see how Milton used the classical epic characteristics and conventions in his writing. It was by employing these methods in to an already well known story that Milton created a masterpiece. Francis C. Blessington seems to sum it up the best. "Milton built his epic out of those of Homer and Virgil, like a cathedral erected out of the ruins of pagan temples whose remains can still me seen" (xiii). Bibliography: Works Cited Blessington, Francis C. Paradise Lost and the Classical Epic. Boston: Routledge, 1979. Milton, John. "Paradise Lost." The Norton Anthology of English Literature. Ed. M. H. Adams. New York: W. W. Norton & Company, 1993. 1475-1495.

They Are More Complex Than You Think

Case Corporate Bonds – They are More Complex Than You Think 1. How should Jill go about explaining the relationship between coupon rates and bond prices? Why do the coupon rates for the various bonds vary so much? Jill should explain the relationship between coupon rates and bond prices by calculating the price of the bonds, which have similar features except coupon rate. Let’s compare ABC Energy issuer with the coupon rate 5% and 0% (the same with rating and YTM) IssuerMaturityFace ValueCoupon RateRatingYieldPrice% Change ABC Energy2010005%AAA2%$1,490. 54 49. 05% ABC Energy2010005%AAA3%$1,297. 55 29. 5% ABC Energy2010005%AAA5%$1,000. 00 0. 00% ABC Energy2010005%AAA6%$885. 30 -11. 47% ABC Energy2010000%AAA2%$672. 97 -32. 70% ABC Energy2010000%AAA3%$553. 68 -44. 63% ABC Energy2010000%AAA5%$376. 89 -62. 31% ABC Energy2010000%AAA6%$311. 80 -68. 82% The table shows that the 5% coupon bond has a wider fluctuation in price than the zero coupon bond for equivalent changes in y ield. 2. How are the ratings of these bonds determined? What happens when the bond ratings get adjusted downwards? The ratings of these bonds are determined by two professional bond-rating firms: Moody’s and Standard & Poor’s (S&P).Each of these bond-rating firms has a committee that evaluates the risk level of the company’s bond issue. It assigns a rating ranging from AAA or Aaa (best rating) down to D (default). The ratings are periodically re-evaluated whenever there is a significant development in a company’s structure or earning performance. When the ratings get adjusted downward, the bond becomes less attractive. Hence, the rate of return goes up to reduce its price. 3. During the presentation one of the clients is puzzled why some bonds sell for less than their face value while others sell for premium.She asks whether the discount bonds are a bargain. How should Jill respond? Bonds can be issued at a discount, at par, or even at premium from face v alue. The majority of bonds are sold at par ($1,000) with the coupon rate being set equal to the yield that proportional with its rating and maturity. After it is being issued, the yields demanded by investors will change, but the coupon rate still stays the same. If the yield exceeds the coupon rate, investors are demanding a higher rate of return than what the company is currently paying via the coupon payment, which leads the price drops and vice versa.As long as the yields are a true reflection of the risk level of the bond, there would not be any a bargain for the bond price, whether at a discount or premium from face value. 4. What does the term â€Å"yield to maturity† mean and how is it to be calculated? The â€Å"yield to maturity† (YTM) of a bond is the rate of return that an investor expects to earn when he or she buys the bond at its current price, receive the face value when it matures. The YTM is considered a long-term bond yield expressed as an annual ra te. The YTM of a bond is also known as its promised yield.To calculate a bond’s YTM, we must use the following inputs: For example: ABC Energy, 5%, 20 years, face value $1,000, price $703. 1 (semi-annual coupons) PV= -703. 1, N=40, PMT = 25, FV = 1000 => I = 4 (semi-annual) Interest annual = 4%*2 = 8 % 5. What is the difference between the â€Å"nominal† and effective yields to maturity for each bond listed in Table 1? Which one should the investor use when deciding between corporate bonds and other securities of similar risk? Please explain. IssuerFace ValueCoupon Rate Rating Quote PriceYTM Sinking FundCall Period YTM (semi-annual)Nominal YTMEffective YTM ABC Energy 10005%AAA703. 20yes34. 0001%8. 0001%8. 1601% ABC Energy 10000%AAA208. 320yesn/a3. 9999%7. 9997%8. 1597% TransPower100010%AA109220yes54. 5000%9. 0001%9. 2026% Telco Utilities100011%AA1206. 430no54. 4999%8. 9998%9. 2023% The nominal yield to maturity on the bond is calculated by multiplying the semi-annual y ield by two. The effective YTM is calculated by compounding the semi-annual yield for two periods. For example, on the ABC Energy 5%, 20 year bond, the semi-annual YTM is 4%. The effective annual YTM would be calculated [(1+0. 4)^2]-1 = 0. 0816 or 8. 16%.Since the YTM is a promise yield with the actual yield being dependent on the reinvestment rate that each investor is able to earn, it is best to compare similar risk bonds on the basis of their nominal YTMs. 6. Jill knows that the call period and its implications will be of particular concern to the audience. How should she go about explaining the effects of the call provision on bond risk and return potential. Call provisions are attached to bonds so that it allows companies to refinance their debt at lower rates when interest rates drop.The existence of a call provision presents a risk to the bond investor that their investment horizon on that bond may be prematurely ended. Moreover, there is reinvestment risk associated with cal lable bonds, since the bonds are called when rates are low. The company does pay a premium when the bond is called. Furthermore, there is a deferred call period for five years, which the bond can’t be called. In the case of callable bonds, investors should calculate the yield to the first call of the bonds to decide.For this calculate, the future value is set to equal to $1,000 + 1 year coupon, the maturity is assumed to be the number of years until the bond become callable. 7. How should Jill go about explaining the riskiness of each bond? Rank the bonds in terms of their relative riskiness. IssuerFace ValueCoupon Rate Rating Quote PriceYTM Sinking FundCall Period YTM (semi-annual)Nominal YTMEffective YTMRisk Rank (1=low) ABC Energy 10005%AAA703. 120yes34. 0001%8. 0001%8. 1601%1 ABC Energy 10000%AAA208. 320yesn/a3. 9999%7. 9997%8. 1597%2 TransPower100010%AA109220yes54. 5000%9. 001%9. 2026%3 Telco Utilities100011%AA120630no54. 4999%8. 9998%9. 2023%4 The bond ratings provide a general guide as to the credit risk associated with each bond. Within it ratings, investors need to be aware of call risk, reinvestment risk, maturity, and the sinking fund provision’s effect on risk. Callability makes a bond have a higher reinvestment risk. Among the AAA bonds, the zero coupon bond has no call risk, no reinvestment risk, but the higher price risk. Among the AA bonds, Telco Utilities has a longer maturity and no sinking fund making it the riskiest. . One of Jill’s best clients poses the following questions, â€Å"If I buy 10 of each of these bonds, reinvest any coupons received at the rate of these bonds, reinvest any coupons received at the rate of 5% per year and hold them until they mature, what will my realized return be on each bond investment? † How should Jill respond? IssuerFace ValueCoupon Rate Quote PriceYTM Sinking FundCall Period YTM (semi-annual)Nominal YTMEffective YTMFV of couponFV of coupon + FVRealized Return (Semi-Annual)Reali zed Return ABC Energy 10005%703. 120yes34. 0001%8. 001%8. 1601%$1,685. 06 $2,685. 06 3. 41%6. 81% ABC Energy 10000%208. 320yesn/a3. 9999%7. 9997%8. 1597%$0. 00 $1,000. 00 4. 00%8. 00% TransPower100010%109220yes54. 5000%9. 0001%9. 2026%$3,370. 13 $4,370. 13 3. 53%7. 06% Telco Utilities100011%120630no54. 4999%8. 9998%9. 2023%$7,479. 54 $8,479. 54 5. 00%9. 99% In the case of the ABC Energy, 5% coupon bond, the realized return is calculated as follows: Future value of reinvested coupon N=40, I = 2. 5, PV=0, PMT=25 => FV= 1685. 06 Realized return = [(1685. 06+1000)/703. 1]^(1/40) -1 = 3. 41% *2 = 6. 82%

Diet And Its Effects On Society - 2213 Words

Introduction Since civilisation began, diet has been a crucial aspect of human life. Apart from being vital, it has been a part of the culture over the centuries. When food is consumed, it gives the energy needed for our daily life activities. Food consumed on a regular basis is called a diet, and uniquely almost everyone has his or her special diet (Elishason, 2016). The development of diet is affected by various factors such as culture, geographical position, and religious belief. Over time, these diets might be influenced by other factors, for instance, the health condition of a person, the age, social exposure, and cost of the food. There are thousands of different diets in the world. Some are considered healthy diets and others†¦show more content†¦This essay will discuss the increase of fast food diets in the world and it will consider the possible future impact on children as they grow into adults. What is a fast food diet? Fast food is food prepared in large quantities within a short period of time. When this food is regularly consumed, it is called a fast food diet. Fast food is often referred to as junk food because it has a high fats content, carbohydrate, sodium and sugar. Such food includes French fries, salted chips, chocolate bars and biscuits, doughnuts and soda drinks are included in this category. (Green, 2014). The ingredients used in fast food are often made with cheaper precooked and less nutritious ingredients thus; they are often regarded as unhealthy. Fast food can mostly be found in quick-serve restaurants such as McDonalds, KFC, and Burger King. Regularly consuming these foods could lead to health complications such as high blood pressure, cardiovascular disease, and obesity (CYWH, 2015). The emergence of Fast food in developed countries. The United States is the originator of fast food, which has led to fast food being universally regarded as western food in many eastern countries (Durankiev, 2015). Fast food first spread to Canada in 1953, then to Germany in 1962 and outsourcing to the Asia country such as Japan that happened in 1970. The expansion was due to the American armed forces occupation in various countries, which help to ensure the American armed forces have access