MUS 17 University of California San Diego Hip Hop Songs Analysis and Comparison Paper.
Two songs that are covered during the first four lectures will be compared and contrasted. The songs must be chosen from the provided lists- one from list one and one from list 2 -and the paper should be no shorter than 3 pages (excluding bibliography). A bibliography must be included with proper citations for the songs themselves and at least 2 proper references.Be sure to listen to all of the songs and choose ones that you feel that you may have a lot to say about, and remember, you’re comparing the songs not how you feel about the songs.One of the references should be “Stinging Like Tabasco” by Imani PerryRubrik:Starting PointsYou do what’s asked –2 songs from the lists, 3 pages long, bibliography, both compare and contrast the songs, offer equal opinion and insight into both songs, offer proper support for info=15 pts before deductions.Miss major elements –only one song, songs are from the same list or are not on the list, no bibliography, 1.5 pages or less. –7.5 points before deductions.Deductions at the discretion of the TA, but examples include unsupported/wrong information, incorrect citations, obviously poor effort, didn’t compare songs but wrote about how one feels about the songs, skate.Song lists for the assignmentList OneDe La Soul –Me, Myself and IRoxanne Shante – Roxanne’s RevengeGrandmaster Flash –The MessagePublic Enemy –Don’t Believe the HypeList TwoKurtis Blow –The BreaksSnoop Dogg –Who Am I ?ODB – Brooklyn Zoo2 Live Crew – Me So HornySome content ideas: Use Imani Perry’s “Stinging Like Tabasco” to compare the types of flow.Compare the way that the beat is createdCompare the use of “Signifying” in the lyrics.Compare the environments that the songs came from and how we hear them.Compare the intention of the lyrics.Compare anything else that you hear and that you feel is important to understanding the songs !
Web-Based Technology Report Report. Introduction Facebook, widely regarded as the most popular social networking sites among students, is created to connect users. It allows people to customize their profiles with personal information such as pictures, relationships and personal interests. What’s more, all Facebook users from a common region or users who list a certain movie or music as a favourite form a group. Under user profiles, each of these portions of information constitutes a link. When a user clicks on one of these links, it shows information of other users in the network that incorporated that aspect in their profiles. Other links are further structured around user-created clusters that usually depict expressive labels such as name of a fraternity or feminism is fun (Educause Learning Initiative 2006, p. 1). Concerns have emerged regarding the risks posed by Facebook. In some cases, the profiles posted in Facebook do not represent the people behind them. For instance, the urge to gain online popularity may entice some Facebook users to post awkward pictures or data that would otherwise be kept confidential in a different context. Although many students know how to conceal private information from the public sphere, some lack the prudence to depict themselves properly online. In some cases, students may get in trouble regarding photos and comments they post about themselves. In addition, libel and copyright issues may surface when students make inappropriate comments about others or infringe on intellectual property rights of other people. This problem is aggravated by internet caching whereby web content may be accessible even after it has been altered or eradicated from a web site. Addiction is also common among some users who spent many hours daily searching for friends or updating their profiles. An apparently infinite web of links, nevertheless, creates a risk for endless roving, seeing who likes what, who knows who, and how it all integrate, without any precise objective in mind (Educause Learning Initiative 2006, p. 2). Case Study Analysis During the next semester, Angela plans to visit Hungary and study at a university in Budapest. She aspires to gain more information about Hungary before departing. Angela has a Facebook account but she has not updated her profile because she does not use Facebook regularly. Since Angela attends a somewhat small college with limited resources for students who aspire to study overseas, she resolves to learn more about Hungary from other Facebook users. Angela begins by updating her Facebook profile with information about her major and the impending semester in Budapest. She links up with some Facebook groups related to international student exchange programs. Angela uses these groups to locate students at her own college who have previously studied overseas. By communicating with members of these communities, Angela is able to gain immense information about various aspects of overseas studies that she would otherwise find hard to acquire using conventional means. Angela looks for Facebook users with Budapest in their profiles and discovers several students from that region. From their viewpoints, she learns a lot about the past and present political climate of Hungary. Angela then uses this information to carry out Facebook searches focussing on European culture and politics in general (Educause Learning Initiative 2006, p. 1). The Facebook profile of Angela becomes more and more detailed as the weeks progress. Angela then creates new online groups, one of which grows rapidly with over 200 members. Several frequent Facebook users communicate with Angela on a regular basis to update her with new information about Budapest. By the time Angela travels to Hungary, she has a wealth of knowledge about the local weather, culture, restaurants as well as her expectation with respect to the study-abroad program. What’s more, Angela has made online friendships with some students from other universities who will spend their next semester in Hungary. Angela makes plan to meet them for lunch in Budapest during the first week of her arrival (Educause Learning Initiative 2006, p. 1). Several deductions can be made with respect to the scenario presented above. Facebook offers a refined profiling system that enables users to generate detailed data regarding themselves. Profiles usually entail sharing data such as personal interest, location, age, pictures and extra details under the ‘About me’ section. The moment a profile is generated, a user can then be considered as a member of the online community and has access to information shared within the group (HarrisonWeb-Based Technology Report Report
Cyclic Voltammetry Principle. Cyclic voltammetry is the most widely used technique for acquiring qualitative information about electrochemical reactions [34, 35]. The power of cyclic voltammetry results from its ability to provide considerable information on the thermodynamics and kinetics of heterogeneous electron transfer reactions [47, 48], and coupled chemical reactions [36, 37]. It also provides mathematical analysis of an electron transfer process at an electrode [41, 49, 50]. Basic Principle of Cyclic voltammetry An electron transfer process with a single step may be represented as; O ne â‡‹ R (2.1) where O and R are oxidized and reduced form of electoractive species respectively, which either is soluble in solution or absorbed on the electrode surface and are transported by diffusion alone. Cyclic voltammetry consists of scanning linearly the potential of a stationary working electrode (in an unstirred solution), using a triangular potential waveform. Depending on the information sought, single or multiple cycles can be used. During the potential sweep, the potentiostat measures the current resulting from the applied potential. The resulting plot of current vs. potential is termed as cyclic voltammogram. The excitation signal in cyclic voltammetry is given in Fig. 2.1a. Initially the potential of the electrode is Ei. Then the potential is swept linearly at the rate of Î½ volts per second. In cyclic voltammetry reversal technique is carried out by reversing direction of scan after a certain time t =Î» .The potential at any time E (t) is given by E (t) = Ei – Î½t t<Î» (2.2a) E (t) = Ei – 2Î½Î» Î½t tâ‰¥Î» (2.2b) Here”Î½” is scan rate in V/s. The shape of the resulting cyclic voltammogram can be qualitatively explained as follows: When potential is increased from the region where oxidized form “O” is stable, cathodic current starts to flow as potential approaches E0 for R/O couple until a cathodic peak is reached. After traversing the potential region in which the reduction process takes place, the direction of potential sweep is reversed. The reaction-taking place in the forward scan can be expressed as O e- â†’ R During the reverse scan, R molecule (generated in the forward half cycle, and accumulated near the surface) is reoxidized back to O and anodic peak results. R ï‚¾ï‚® O e- In the forward scan as potential moves past Eo, the near-electrode concentration of O falls to zero, the mass transfer of O reaches a maximum rate, in unstirred solution, this rate then declines as the depletion of O further and further from electrode takes place. Before dropping again current passes through a maximum. Reversal of scan repeats the above sequence of events for the oxidation of electrochemically generated R that now predominates in near-electrode region. The continuous change in the surface concentration is coupled with an expansion of the diffusion layer thickness (as expected in the quiescent solutions). The resulting current peaks thus reflect the continuous change of the concentration gradient with time, hence, the increase to the peak current corresponds to the achievement of diffusion control, while the current drop (beyond the peak) exhibits a t-1/2 dependence (independent of the applied potential). For the above reasons, the reversal current has the same shape as the forward one. Electrochemical Cell Electrochemical cell is a sealed vessel which is designed to prevent the entry of air. It has an inlet and outlet to allow the saturation of solution with an inert gas, N2 or Ar. Removal of O2 is usually necessary to prevent currents due to the reduction of O2 interfering with response from system under study. The standard electrochemical cell consists of three electrodes immersed in an electrolyte; Working electrode (WE) Reference electrode (RE) Counter electrode (CE) Working Electrode (WE) The performance of the voltammetric procedure is strongly influenced by the working electrode material. Since the reaction of interest (reduction or oxidation) takes place on working electrode, it should provide high signal to noise characteristics, as well as a reproducible response. Thus, its selection depends primarily on two factors: the redox behaviour of the target analyte and the background current over the potential region required for the measurement. Other considerations include the potential window, electrical conductivity, surface reproducibility, mechanical properties, cost, availability and toxicity. A range of materials have found application as working electrodes for electroanalysis, the most popular are those involving mercury, carbon or noble metals (particularly platinum and gold). Reference Electrode (RE) This functional electrode has a constant potential so it can be used as reference standard against which potential of other electrode present in the cell can be measured. Commonly used reference electrodes are silver-silver chloride or the calomel electrode. Counter of Auxiliary Electrode (CE) It is also termed as auxiliary electrode and serves as source or sink for electrons so that current can be passed from external circuit through the cell. The potential at WE is monitored and controlled very precisely with respect to RE via potentiostat. This may be controlled in turn via interfacing with a computer. The desired waveform is imposed on the potential at the WE by a waveform generator. The potential drop V is usually measured by the current flowing between the WE and CE across a resistor R (from which (I=V/R), the latter connected in series with the two electrodes. The resulting I/V trace, termed as a voltammogram is then either plotted out via an XY chart recorder or, where possible, retained in a computer to allow any desired data manipulation prior to hard copy being taken. Single Electron Transfer Process Three types of single electron transfer process can be studied. Reversible process Irreversible process Quasi-reversible process Based on values of electrochemical parameters, i.e. peak potential Ep, half peak potential (Ep/2), half wave potential (E1/2), peak current (ip), anodic peak potential Epa, cathodic peak potential Epc etc, it can be ascertained whether a reaction is reversible, irreversible or quasi-reversible. Ep is the potential corresponding to peak current ip, Ep/2 is the potential corresponding to 0.5 ip, E1/2 is the potential corresponding to 0.85 ip. These electrochemical parameters can be graphically obtained from the voltammogram as shown in the Fig. 2.2. Reversible Process The heterogeneous transfer of electron from an electrode to a reducible species and vice versa O ne â‡‹ R is a form of Nernstian electrode reaction with assumption that at the surface of electrode, rate of electron transfer is so rapid that a dynamic equilibrium is established and Nernstian condition holds i.e. CO(0,t) âˆ• CR(0,t) = Exp[(nFâˆ•RT)(Ei-Î½t-Eo)] (2.3) In equation (2.3), Co and CR are concentration of oxidized and reduced species at the surface of electrode as a function of time, Eo is the standard electrode potential, Ei is the initial potential and Î½ is the scan rate in volts per second. Under these conditions, the oxidized and reduced species involved in an electrode reaction are in equilibrium at the electrode surface and such an electrode reaction is termed as a “reversible reaction”. Current Expression Due to difference in concentration of electroactive species at the surface of electrode and the concentration in the bulk, diffusion controlled mass transport takes place. Fick’s second law can be applied to obtain time dependent concentration distribution in one dimension of expanding diffusion layer. âˆ‚Ci(x, t) âˆ•âˆ‚t = Diâˆ‚2Ci(x, t) âˆ•âˆ‚x2 (2.4) Peak current is a characteristic quantity in reversible cyclic voltammetric process. The current expression is obtained by solving Fick’s law . i = nFACo*(Ï€Doa)1/2 Ï‡(at) (2.5) where i = current, n = number of electrons transferred, A is the area of electrode, Co* is the bulk concentration of oxidized species, Do is the diffusion coefficient, Ï‡ (at) is the current function and a = nFÎ½/RT At 298K, function Ï‡(at) and the current potential curve reaches their maximum for the reduction process at a potential which is 28.5/n mV more negative than the half wave potential i.e. at n(Ep-E1/2) = – 28.50 mV, Ï€1/2Ï‡(at) = 0.4463 ( Table 2.1). Then the current expression for the forward potential scan becomes (2.6) where ip is the peak current or maximum current. Using T=298K, Area (A) in cm2, Diffusion coefficient (Do) in cm2/s, concentration of species O (Co*) in moles dm-3 and Scan rate (Î½) in volts sec-1, equation (2.6) takes the following form, (2.7) Equation (2.7) is called Randle’s Sevick equation [39, 40]. Diagnostic Criteria of Reversibility Certain well-defined characteristic values can be obtained from the voltammogram, for a reversible electrochemical reaction. Relationship between peak potential (Ep) and half wave potential (E1/2) for a reversible reaction is given by, (2.8a) (2.8b) Where E1/2 is potential corresponding to i = 0.8817ip . At 298 K (2.8c) From equations (2.8a) and (2.8b) one obtains, (2.9a) At 298K (2.9b) The peak voltage position does not alter as scan rate varies. In some cases, the precise determination of peak potential Ep is not easy because the observed CV peak is somewhat broader. So it is sometimes more convenient to report the potential at i = 0.5ip called half peak potential, which can be used for E1/2 determination . (2.10a) At 298 K (2.10b) (2.10c) From equations (2.8a) and (2.10a) we obtain, (2.11a) At 298K (2.11b) The diagnostic criterion of single electron transfer reversible reaction is often sufficient to get qualitative as well as quantitative information about the thermodynamic and kinetic parameters of the system. For a reversible system, should be independent of the scan rate, however, it is found that generally increases with ï®. This is due to presence of finite solution resistance between the reference and the working electrode. Irreversible Process For a totally irreversible process, reverse reaction of the electrode process does not occur. Actually for this type of reaction the charge transfer rate constant is quite small, i.e. ksh ï‚£ 10-5cm sec-1, hence charge transfer is extremely low and current is mainly controlled by the rate of charge transfer reaction. Nernst equation is not applicable for such type of reaction. The process can be best described by the following reaction O ne ï‚¾ï‚® R Delahay  and later on Mastuda, Ayabe , and Reinmuth  described the stationary electrode voltammetric curves of the irreversible process. Irreversibility can be diagnosed by three major criteria. A shift in peak potential occurs as the scan rate varies. Half peak width for an irreversible process is given by (2.12) Here Î± is transfer coefficient and na is the number of electrons involved in rate determining step of charge transfer process. At 298K (2.13) Current expression is given as, i = nFACo*(Ï€Dob)1/2 Ï‡(bt) (2.14) The function Ï‡(bt) goes through a maximum at Ï€1/2Ï‡(bt) = 0.4958.(Table 2.2). Introduction of this value in equation (2.14) yields the expression (2.15) for the peak current. A plot of ln ip vs. (Ep-Eo) for different scan rates would be a straight line with a slope proportional to -ï¡naF and an intercept proportional to ks,h. Quasi-reversible Process Quasi-reversible process is termed as a process which shows intermediate behaviour between reversible and irreversible processes. Both charge transfer and mass transfer control current of the reaction. For quasi-reversible process value of standard heterogeneous electron transfer rate constant, ks,h lies between 10-1 to 10-5 cm sec-1. Cyclic voltammogram for quasi-reversible process is shown in Fig. 2.3. An expression relating the current to potential dependent charge transfer rate was first provided by Matsuda and Ayabe . (2.17) where, ksh is the heterogeneous electron transfer rate constant at standard potential Eo of redox system,is the transfer coefficient and ï¢ = 1- ï¡. In this case, the shape of the peak and the various peak parameters are functions of ï¡ and the dimensionless parameter ïŒ, defined as  (2.18) For quasi-reversible process current value is expressed as a function of. (2.19) where is expressed as (2.20) is shown in Fig. 2.4. It is observed that when ïŒ > 10, the behavior approaches that of a reversible system. It is observed that for a quasi-reversible reaction, ip is not proportional to ï®1/2. For half peak potential we have at 298K (2.21) This implies, These parameters attain limiting values characteristic of reversible or totally irreversible processes as ïŒ varies. For ïŒ >10, ï„(ïŒ,ï¡) = 2.2 which gives Ep-Ep/2 = 56.5mV (value characteristic of a reversible wave). For < 10-2, ï¡ = 0.5, ï„(ïŒ,ï¡) =3.7, which yields totally irreversible characteristics. Thus a system may show Nernstian, quasi-reversible, or totally irreversible behaviour depending on ïŒ, or experimentally on the scan rate employed. At small Ï… (or long times), systems may yield reversible waves, while at large (or short times), irreversible behaviour is observed . Variation of Î” with Î› and Î± is shown in Fig. 2.5. For three types of electrode processes Matsuda and Ayabe  suggested following zone boundaries. a) Reversible (Nernstian) Î›ï‚³15; ksh ï‚³ 0.3 Ï…1/2cm s-1 b) Quasi-Reversible 15ï‚³ Î› ï‚³ 10-2 (1 Î±); 0.3 Ï…1/2 ï‚³ ksh ï‚³ 2 10-5 Ï…1/2 cm s-1 c) Totally Irreversible Î› < 10-2 (1 Î±); ksh < 2 10-5 Ï…1/2 cm s-1 Source: Bard, A.J.; Faulkner, L.R. Electrochemical Methods, Fundamentals and Applications, John Wiley, New York, 1980, pp 225. Source: Bard, A.J.; Faulkner, L.R. Electrochemical Methods, Fundamentals and Applications, John Wiley, New York, 1980, pp 227. Multi Electron Transfer Process Multi-electron transfer process usually takes place in two separate steps. Two-steps mechanism, each step characterized by its own electrochemical parameters is called “EE mechanism”. Stepwise reversible “EE mechanism” is given by following reaction, A n1e â‡‹ B (E10) (2.22a) B n2e â‡‹ C (E20) (2.22b) where, A and B are electroactive species and n1 and n2 are the number of electrons involved in successive steps. If A and B react at sufficiently separated potentials with A more easily reducible than B, the voltammogram for overall reduction of A to C consists of two separated waves. The first wave corresponds to the reduction of A to B with n1 electrons and in this potential range the substance B diffuses into the solution. As potential is scanned towards more cathodic values, a second wave appears which is made up of two superimposed parts. The current related to substance A, which is still diffusing toward electrode increases since this species now is reduced directly to substance C by (n1 n2) electrons. In addition, substance B, which was the product of the first wave, can be reduced in this potential region and a portion of this material diffuses back towards the electrode and reacts. Each heterogeneous electron transfer step is associated with its own electrochemical parameters i.e. ks,hi and Î±i, where i =1, 2 for the 1st and 2nd electron transfer respectively. Based on the value of ï„Eo, we come across three different types of cases  as shown in the Fig. 2.6. Types of Two Electron Transfer Reactions  Case 1: Separate Peaks When ï„Eo ï‚³ -150mV the EE mechanism is termed as “disproportionate mechanism . Cyclic voltammogram consists of two typical one-electron reduction waves. The heterogeneous electron transfer reaction may simultaneously be accompanied by homogenous electron transfer reactions, which in multi-electron system leads to disproportionation. Each disproportionation reaction can be described as, 2R1 â‡‹ O R2 (2.23) The equilibrium constant K (disproportionation constant) is given by (2.24) It can be derived from the difference between the standard potentials using (2.25) Case 2: < 100mV —-Peaks Overlapped In this case, the individual waves merge into one broad distorted wave whose peak height and shape are no longer characteristics of a reversible wave. The wave is broadened similar to an irreversible wave, but can be distinguished from the irreversible voltammogram, in that the distorted wave does not shift on the potential axis as a function of the scan rate. Case 3: = 0mV Single peak In this case, in cyclic voltammogram, only a single wave would appear with peak current intermediate between those of a single step one electron and two electron transfer reactions and Ep-Ep/2 = 21 mV. Case 4: E1o < E2o—-2nd Reduction is Easy than 1st one If the energy required for the first second electron transfer is less than that for the first, one wave is observed having peak height equal to 23/2 times that of a single electron transfer process. In this case, Ep – E1/2 = 14.25 mV. The effective E0 for the composite two electron wave is given by . Source: Polcyn, D.S.; Shain, I. J. Anal. Chem. 1966, 38, 370. Cyclic Voltammetric Methods for the Determination of Heterogeneous Electron Transfer Rate Constant Cyclic voltammetry provides a systematic approach to solution of diffusion problems and determination of different kinetic parameters including ks,h. Various methods are reported in literature to determine heterogeneous rate constants. Nicholson [41, 42], Gileadi  and Kochi  developed different equations to calculate heterogeneous electron transfer rate constants. Nicholson’s Method [41, 42] Nicholson derived an expression for determination of heterogeneous electron transfer rate constant ksh. This method is based on correlation between and ks,h through a dimensionless parameter by following equation, (2.26) where is scan rate. for different values of Î”Ep can be obtained from the Table 2.3. Hence, if Î”Ep (Epa-Epc) is determined from the voltammogram, can be known from Table 2.3. From the knowledge of, , ksh can be calculated using equation (2.27). If D o= DR then Î³=1 (2.27) This method is applied for voltammograms having peak separation in the range of 57mV to 250mV, and between this range, the electrode process progresses from reversible to irreversible. With increasing scan rate, the peak separation and hence Ïˆ decreases. It can be seen from the Table 2.3, that for reversible reactions i.e. for the current voltage curves and is independent of . For totally irreversible reaction i.e. for the back reaction becomes unimportant, anodic peak and is not observed. For quasi-reaction i.e. for 0. 001<<7, the form of current curves and depends upon . Separation of cathodic and anodic peak potential as a function of the kinetic parameter ï¹ in the cyclic voltammogram at room temperature. Kochi’s Method Kochi and Klinger  formulated another correlation between the rate constant for heterogeneous electron transfer and peak separation. The expression for ksh given by Kochi was (2.28) The standard rate constant ksh can be calculated from the difference of peak potentials and the sweep rates directly. This equation applies only to sweep rates which are large enough to induce electrode irreversibility. The relation derived by Kochi is based on following expressions derived by Nicholson and Shain . (2.29a) (2.29b) where Î² = 1-Î± , and Ï… is the scan rate. Equations (2.29a) and (2.29b) yield (2.30) This expression is used for the determination of the transfer coefficient. Assuming that (for reversible reaction). We have, (2.31) Gileadi’s Method Gileadi  formulated a more sophisticated method for the determination of heterogeneous electron transfer rate constant, ks,h, using the idea of critical scan rate, c. This method can be used in the case where anodic peak is not observed. When reversible heterogeneous electron transfer process is studied at increasing scan rates, peak potential values also vary and process progresses towards irreversible. If are plotted against the logarithm of scan rates, a straight line at low scan rates and ascending curve at higher scan rate is obtained. Extrapolation of both curves intersects them at a point known as “toe”. This “toe” corresponds to the logarithm of critical scan rate, c. as shown in Fig. 2.7. Hence critical scan rate can be calculated experimentally. ks,h can be calculated as, (2.32) where Ï…c is the critical scan rate, Î± is a dimensionless parameter, called transfer coefficient and Do is the diffusion coefficient. Coupled Chemical Reactions Although charge transfer processes are an important part of entire spectrum of chemical reactions, they seldom occur as isolated elementary steps. Electron transfer reactions coupled with new bond formation or bond breaking steps are very frequent. The occurrence of such chemical reactions, which directly affect the available surface concentration of the electroactive species, is common to redox processes of many important organic and inorganic compounds. Changes in the shape of the cyclic voltammogram resulting from the chemical competition for the electrochemical reactant or product, can be extremely useful for elucidating the reaction pathways and for providing reliable chemical information about reactive intermediates . It is convenient to classify the different possible reaction schemes in which homogeneous reactions are associated with the heterogeneous electrons transfer steps by using letters to signify the nature of the step. E represents an electron transfer at the electrode surface, and C represents a homogenous chemical reaction. While O and R indicate oxidized and reduced forms of the electroactive species, other non electroactive species which result from the coupled chemical complication are indicated by W, Y, Z, etc . The order of C with respect to E then follows the chronological order in which the two events occur . So according to sequence of step, the systems are classified as EC, ECE, CE etc. These reactions are further classified on basis of reversibility. For example, subclasses of EC reactions can be distinguished depending on whether the reactions are reversible (r), quasi-reversible (q), or irreversible (i), for example Er Cr, ErCi, EqCi, etc. Two Steps Coupled Chemical Reactions In two steps reactions, a variety of possibilities exist, which include chemical reactions following or preceding a reversible or an irreversible electron transfer [59, 60, 61, 62]. The chemical reactions themselves may be reversible or irreversible. a) Preceding Chemical Reactions (CE) In a preceding chemical reaction, the species O is the product resulting from a chemical reaction. Such a reaction influences the amount of O to be reduced so forward peak is perturbed. For a preceding chemical reaction, two mechanisms are possible, depending on whether the electron transfer is reversible CrEr or irreversible CrEi . Reversible Electrode Process Preceded by a Reversible Chemical Reaction (CrEr Reaction) The process in which a homogeneous chemical reaction precedes a reversible electron transfer is schematized as follows: (2.33) where Y represents the non electroactive species and O and R are the electroactive congeners. Since the supply of electroactive species O results from the chemical reaction, it is important to know that how much of O is formed during the time scale of cyclic voltammogram. In this connection, it must be noted that the time scale of voltammetry is measured by the parameter a = nFÏ…/RT for a reversible process and b = Î±naFÏ…/RT for a quasi reversible or an irreversible process It means that the time scale of cyclic voltammetry is a function of the scan rate, in the sense that higher the scan rate, the higher is the competition of the voltammetric intervention with respect to the rate of chemical complication. The limit at which the chemical complication can proceed is governed either by the equilibrium constant K or the kinetics of the homogeneous reaction (l = kf kr). In this regard, it is convenient to distinguish three limiting cases depending on the rate of chemical complication . Slow preceding chemical reaction (kf kr < 20) most of O will already be present in solution, the response is apparently not disturbed by the latter, i.e. it appears as a simple reversible electron transfer. When K is small, the small electron transfer again appears as a simple reversible process except that the peak current will be smaller than is expected on the basis of quantity of Y in the solution. This results because the concentration of the electroactive species CO, being determined by the equilibrium of the preceding reaction is equal to a fraction of species Y placed in the solution. where C* = CO (x,0) CY(x,0) Fast preceding chemical reaction (kf kr >> nFÏ…/RT) When K is large, once again the response appears as a simple reversible electron transfer, but the measured standard potential Eo/* is shifted toward more negative values compared to the standard potential Eo/ of the couple O/ R by a factor of . When K is small, because of the fast continuous maintaining of the small equilibrium amount of O, the complete depletion of O at the electrode surface will never be reached, so that the forward profile no longer maintains the peak shape form, rather assumes a sigmoidal S-shaped curve, the height of which remains constant at all scan rates. Intermediate preceding chemical reaction (kf kr = nFÏ…/RT) In this case, the kinetics can be studied using the ratio between the kinetic and the diffusive currents according to the relationship (2.34) Irreversible Electrode Process Preceded by a Reversible Chemical Reaction (CrEi Reaction) This process is schematizes as. (2.35) In this case, not only the thermodynamic K (kf / kr) and kinetic (kf kr) parameters of preceding chemical reaction but also the kinetic parameters of the electron transfer (Î±, k0) play a role. Obviously the lack of reverse peak is immediately apparent, due to the irreversibility of the charge transfer. The curves are also more drawn out because of the electron transfer coefficient, Î±. Slow preceding chemical reaction (kf kr << nFÏ…/RT) In this case, the process appears as a simple irreversible electron transfer. The peak height of the process depends on the equilibrium constant because, as mentioned in the previous case, the concentration of the active species CO is a fraction of the amount C* put in the solution: Fast preceding chemical reaction (kf kr >> nFÏ…/RT) If instead the reaction kinetics is fast, there are two possibilities: If K is large, again the response appears as if the preceding chemical reaction would be absent. However, the peak potential is shifted towards more negative values than those that would be recorded in the absence of the chemical complication by a factor equal to . If K is small, as in the preceding case, an easily recognizable S-like curve voltammogram is obtained having a limiting current independent from the scan rate (2.36) Intermediate preceding chemical reaction (kf kr = nFÏ…/RT) Here again, the kinetics can be studied using the ratio between the kinetic and diffusive currents according to the relationship (2.37) b) Following Chemical Reactions (EC) The process in which the primary product of an electron transfer becomes involved in a chemical reaction is indicated by EC mechanism. It can be represented by O ne â‡‹ R R â‡‹ Z (2.38) where O and R are the electroactive congeners and Z represents the non electroactive species. Several situations are possible depending on the extent of electrochemical reversibility of the electron transfer and on the reversibility or irreversibility of the chemical reaction following the electron transfer. As a general criterion, in cyclic voltammetry, the presence of a following reaction has little influence on the forward peak, whereas it has a considerable effect on the reverse peak. Reversible Electrode Process Followed by a Reversible Chemical Reaction (ErCr Reaction) ErCr mechanism can be written as (2.39) Once again the voltammetric response will differ to a greater or lesser extent with respect to a simple electron transfer depending on the values of either the equilibrium constant, K, or the kinetics of the chemical complication (kf kr) . Analogously to that discussed for preceding equilibrium reactions, three limiting cases can be distinguished. Slow following chemical reaction (kf kr << nFÏ…/RT) If the rate of chemical reaction is low, it has a little effect on the process, thus reducing it a simple reversible electron transfer. Fast following chemical reaction (kf kr >> nFÏ…/RT) If the rate of the chemical complication is high, the system will always be in equilibrium and the voltammogram will apparently look like a non complicated reversible electron transfer. However, as a consequence of the continual partial removal of the species R from the electrode surface, the reduction occurs at potential values less negative than that of a simple electron transfer by an amount of . Due to the fast kinetics of the chemical complication, the potential will remain at this value regardless of the scan rate. Intermediate following chemical reaction (kf kr=nFÏ…/RT) If the kinetics of the chemical reaction are intermediate with the scan rate the response gradually shifts from previous value for a fast chemical reaction [which was more anodic by w.r.t. to value of the couple O/R] towards the Eo/ value assuming more and more the values predicted by the relationship (2.40) In other words, the response (which for the fast kinetics is more anodic compared to E0/) due to the competitive effects of the potential scan rate moves towards more cathodic values by 30/n (mV) for every ten fold increase in the scan rate. However, it is noted that at the same time, the reversible peak tends to disappear, in that on increasing the scan rate, the species Z does not have time to restore R. This is demonstrated by the current ratio which is about one at low scan rates, but it tends to zero at high scan rates. Reversible Electrode Process Followed by an Irreversible Chemical R Cyclic Voltammetry Principle
MBA 640 Maryland Global Campus Researching Consumer Buying Behavior Project.
MUS 17 University of California San Diego Hip Hop Songs Analysis and Comparison Paper
Project 1: Researching Consumer Buying BehaviorStep 5: Complete Your Value PropositionEarly in Week 2, submit a one-page value proposition to Erik.INBOX: 1 New MessageFrom: Erik Knops, CEO, ACMETo: YouJust a quick note,I wanted to clarify that a customer-focused value proposition explains the reason why a customer purchases a product or uses a service (i.e., the value that a company delivers to its customers).Deliverable: Based on your research of consumer needs in our main markets, describe your value proposition, or the benefits that ACME and its potential new product would provide to customers. Remember, a value proposition is essentially the promise that is made to the customer. Also provide a half-page recommendation to ACME on whether or not to manufacture that product.Support your work with the course readings, scholarly sources, and reliable nonscholarly sources, such as Reuters, Bloomberg, Yahoo! Finance, Barrons.com, Morningstar.com, Money, Forbes, Fortune, the Financial Times, the Wall Street Journal, and the Harvard Business Review, as well as the UMUC Library databases, such as Hoover’s. All sources need to be cited using APA formatting, both within the text and in the reference list. The value proposition should be organized using headings and subheadings to improve its readability.I know these are tight turnarounds, but I have no doubt you’ll knock this out,ErikSubmit your report to the dropbox located in the final step of this project. In the next step you will finalize your consumer buying behavior report and write an executive summary.Project 1: Researching Consumer Buying BehaviorStep 6: Complete Your Final Consumer Buying Behavior ReportDeliverable: By the end of Week 2, combine the first two deliverables into a single report after making any necessary corrections, and edit them to ensure that there is clear flow of ideas from one section to the other. In addition, include a one-page executive summary that highlights the most important findings of the report; as well as your recommendation as a consultant at the end of the report. APA style should be applied to in-text citations and in the reference list.Your final report to Erik should be eight to nine pages, excluding cover page, executive summary, the reference list, and appendices. Any graphs, tables, and figures should be included as appendices. Your report should have one-inch margins and be double spaced in 12-point Times New Roman font. The report should be organized using headings and subheadings to improve its readability.Submit your report to the dropbox located in the final step of this project.
MBA 640 Maryland Global Campus Researching Consumer Buying Behavior Project
South Univ Why Was First Ct Scan Negative Explain Its Implication On BWs Care Ques
South Univ Why Was First Ct Scan Negative Explain Its Implication On BWs Care Ques.
Answer the discussion questions based on the patient profile, objective and subjective data. StrokePatient ProfileB.W. is a 72-year-old white female admitted 2 days ago to the medical unit with a stroke. She has left-sided hemiparesis. A noncontrast CT scan, about 2 hours after the onset of symptoms, was negative. A second CT scan, 12 hours later, was positive for an ischemic area in the right hemisphere.Objective DataPhysical Examination• Pupils equal, round, reactive to light and accommodation• Decreased sensation in left lower extremity, no sensation in left upper extremity, normal sensation to right upper and lower extremity• 0/5 strength left upper extremity, 1+/5 left lower extremity, 5/5 right upper and lower extremity• Left facial droop• Slurred speechDiagnostic Studies• A barium swallow study has been ordered for 1:00 PMSubjective DataDaughter is at the bedside, she is upset and tearful, stating “Mom doesn’t know where she is and she keeps waving her arm at me and getting upset, trying to tell me something, and I don’t know what she is trying to tell me.”Discussion Questions1. Why was the first CT scan negative? What implication did this have on B.W.’s care? 2. What is the difference between an ischemic and a hemorrhagic stroke?3. What are the different manifestations of right-sided versus left-sided stroke?4. Why was the barium swallow study ordered?5. Based on B.W.’s assessment findings, what are the priority nursing diagnoses?6. Outline a fall risk reduction plan to reduce B.W.’s risk of falling.7. You acknowledge her daughter’s distress and the difficulties that problems with speech can pose of B.W. and her. Describe nursing interventions to assist B.W. impaired communication.
South Univ Why Was First Ct Scan Negative Explain Its Implication On BWs Care Ques
Substance Addiction Treatment in Students Report (Assessment)
python assignment help Table of Contents Introduction Etiology, Signs of Abuse, and Strategies Against Addictions Case Study: Alcohol Abuse Personal Reflection References Introduction Addictions are one of the potential dangers that children are exposed to at school. Smoking, alcohol abuse, substance abuse, and computer addiction have a tremendous impact on school performance in children and adolescents. In addition to grades suffering due to poor concentration and general disinterest in studies, which has an impact on future academic performance and chances of getting into college, addictions also affect the social, physical, and mental capabilities of a child (Brooks
fitting seasonal model question
fitting seasonal model question.
I’m working on a r question and need a sample draft to help me learn.
use the electricity file from the TSA library. This file contains the monthly electricity usage. (a) Plot the data. Discuss a possible model. (b) After transforming the data if necessary, specify a seasonal model for
this data. Include all plots and tables, and justify your choice.
(c) For the model from part (b), estimate the necessary parameters. Justify your choice of method for parameter estimation. (d) Evaluate your model (residual analysis, Ljung-Box, overfitting, etc.).
Is your model from the previous parts appropriate? Justify your answer with supporting tests. If necessary, how would you adjust your
model? (e) Forecast the electricity usage 5 years into the future.
fitting seasonal model question
Healthcare Finance SLP 1
Healthcare Finance SLP 1.
Health Care Financial EnvironmentCongratulations! You were selected as the new assistant to the
Chief Financial Officer of Pearland Medical Center, a 1,000-bed academic
medical center in the suburbs of a city with a population of over 4
million. Pearland Medical Center purchased a Zoll R Series defibrillator,
automatic cardiopulmonary resuscitation (CPR) support machine for its
emergency department, for $20,000 and placed it in service in 2015.
Pearland Medical Center paid $400 to ship the machine. No installation
fees were required. Assume that the chest compression system falls into
the Modified Accelerated Cost Recovery System (MACRS) 5-year class. Calculate the Lucas chest compression system depreciation expense
for tax purposes according to MACRS and its tax book value for each
year.Discuss the relationship between depreciation and taxes for a taxable organization. Length: 3–4 pages, excluding title page and references.SLP Assignment ExpectationsThe following guidance appears only in Module 1, but it applies to the assignments throughout the course:File format: Your work should be prepared using Microsoft Word,
PowerPoint, or Excel depending upon the assignment instructions. For
assignments requiring video or voice recordings, use media formats that
are supported by MyTLC Courses as noted in our Trident Support pageIn-text citations and references: Be sure that all information and
ideas in your papers are supported by in-text citations and
corresponding references at the end of the paper.Scholarly sources: At least two scholarly sources should be included
in your papers. Online sources must be limited to credible professional
and scholarly publications such as peer-reviewed journal articles,
e-books, or specific webpages on websites from a university, government,
or nonprofit organization (these have extensions .edu, .gov, or .org).
Presenting consumer sources such as e-magazines, newspapers, Wikipedia,
WebMD, or other commercial websites (these have extensions .com) as
references is not appropriate.Scholarly writing: Use an academic paper format, not an essay based
on your opinions or experience. Avoid using the first person in writing.
Synthesize what you learned from the sources you read; write papers in
your own words; and cite sources within the text, as well as include a
properly formatted reference list.Use of direct quotes: Use of direct quotes should be avoided. Only
use direct quotes when preserving the exact words of an author is
necessary. In the rare instance that directly quoted material is used,
it must be properly cited (with quotation marks and page numbers in the
in-text citation); quotes should not exceed 5-10% of the total paper
content.Required ReadingAccounting Capital. (2014). What are accounting principles? Retrieved from http://www.accountingcapital.com/basic-accounting/…Laying the groundwork for value-based payment. Healthcare Financial Management, 67(2), 1-4.Speizman, R. A. (2009). Tax-exempt status for hospitals: Where have we been – and where are we going? Healthcare Financial Management, 63(2), 62-66.Tolbert, S. H., Moore, G. D., & Wood, C. P. (2010).
Not-for-profit organizations and for-profit businesses: Perceptions and
reality. Journal of Business & Economics Research, 8(5), 141-153.Optional ReadingInternal Revenue Service. (2016). New requirements for 501(c)(3) hospitals under the Affordable Care Act.
Healthcare Finance SLP 1