A soft option

You may be allowed to take your laboratory reports and other texts into the practical exam. Don t assume that this is a soft option, or that revision is unnecessary you will not have time to read large sections of your reports or to familiarize yourself with basic principles etc. The main advantage of open-book exams is that you can check specific details of methodology, reducing your reliance on memory, provided you know your way around your practical manual. In all other respects, your revision and preparation for such exams should be similar to theory exams. Make sure you are familiar with all of the practical exercises, including any work carried out in class by your partner (since exams are assessed on individual performance). Check with the teaching staff to see whether you can be given access to the laboratory, to complete any exercises that you have missed. 

As a recent article pointed out, there are now a number of U.S. institutions that award Ph.D. s in chemical education research. However, the field continues to be viewed by the majority of mainstream chemists with suspicion, and sometimes even with hostility. It is not uncommon to hear of junior tenure-track faculty who are under undue pressure to perform according to unrealistic criteria set by departments that do not understand, or value, the nature of research in chemical education. Indeed, one hears from some full professors, in the institutions that do have specialists in chemical education, that these are marginalized and misunderstood by their traditional chemical colleagues. It is frequently said that research in chemical education represents a soft option, suited for those who are not capable of succeeding in real chemistry. ... 

The radical anion pathway (e-c-P-d-p Scheme 2) requires a rate-determining protonation after cyclization, i.e., a slow protonation of a hard oxyanion. However, such proton transfer rates are usually diffusion controlled, so this seems unlikely [32,33], On the other hand, the carbanion closure (e-P-d-c-p) portrayed in Scheme 4 requires a very reasonable suggestion that the ratedetermining step corresponds to protonation of the soft, weakly basic radical anion 42, prior to cyclization [32-35] this is the preferred mechanism. One must use caution, however, realizing that these conclusions are drawn for the particular set of substrates which were examined. In some cases, radical anion cyclization remains a viable option. 

Widmer AF. (2008) Ceftobiprole A new option for treatment of skin and soft-tissue infections due to methicillin-resistant Staphylococcus Aureus. Clin Infect Dis 46 656-658. 

Pig. 1. Pulse sequence for selective reverse INEPT. The time-shared homonuclear decoupling during acquisition is optional, and a variety of simplifications may be made to the sequence depending on the instrument used and on the spin system under investigation, as discussed in the text. A DANTE sequence is shown as the selective 90° carbon-13 pulse, but this may be replaced by a soft pulse or some other form of selective excitation. Phase cycling for this sequence is summarized in table 1. 

Ethylene in the polymer provides softness to the product and is low cost. However, the softness in the product often comes at the expense of its wet tensile strength. Increasing the level of self crosslinkable monomer in the polymer often is not a viable option to increase the wet tensile strength. 

Only the azide anion amongst the multitude of possible nitrogen nucleophiles had reported utility in alkynyliodonium salt addition chemistry at the inception of this project. Therefore, extension of this chemistry to amines and amide derivatives occupied our attention at the outset. The requirement for a soft, polarizable nucleophile limited our options, and screening a primary amine as well as some common amide derivatives in the prototype transformation 35 + 36 - 38 led to the first sense that this goal was achievable (Scheme 6).5a c In fact, the common amine protecting group tosyl proved to be the most effective modulator of amine nucleophilicity in this assay. Interestingly, amide pKa does not... 

Should a large tank not be an option, the alternative is multiple skids, some of which will sit idle. The key is to rotate skids on and off so that no one skid experiences most of the down time start-ups. It is also recommended that an off-line or shut-down flush be employed, and that the motor be equipped with a soft start. For the example above, two 350-gpm skids would be required. Both skids would be on line during the 500-gpm draw. A product tank with enough capacity to handle the 200-gpm overage would be required. 

The ESI and APCI are both soft ionization techniques, hence the spectra obtained using these methods are usually very simple and consist predominantly of the pseudomolecular ion. When more information is required, tandem mass spectrometry is a popular option. Several different types of tandem LC/MS systems can be found, with triple quadrupole and ion trap being the most popular choices. Hybrid systems including magnetic sector-quadmpole, magnetic sector-TOF, quadrupole-TOF (Q-TOF) and ion trap-TOF have been described. The most successful among these hybrids is the Q-TOF instrument. 

Convertible instruments are usually issued with attached call or put options. Such features can be implemented into the valuation model. If a soft call feature has been implemented, it enables the issuer to force the conversion when the share price overcomes a percentage or trigger level above the conversion price. However, this option cannot be called in the first years hard call . Differently, after the protection period, the issuer can exercise the option. This second time is referred to soft call . Using the same example shown in Section 9.3.1, we assume that the bond may be redeemed in whole but not in part at their principal amount plus accrued interest on the last 2 years, in which the maturity date is at 20 February 2019. On and after this call date , if the share price exceeds 130% of the conversion price the issuer can force the conversion. Figure 9.23 shows the stock price tree in which at years 4 and 5 the stock price is above the threshold. 

Fig. 4. Staple fiber washing sequence 1, a hot acid wash (2% H2SO4 at 90°C) decomposes and washes out most of the insoluble zinc salts. This wash completes the regeneration of xanthate and removes as much sulfur as possible in the form of recoverable CS2 and H2S 2, an alkaline sodium sulfide desulfurization bath solubilizes sulfurous by-products and converts them into easily removed sulfides 3, a sulfide wash to remove the sulfides created in bath 2 4, a bleach bath (optional) uses very dilute hypochlorite or peroxide to improve fiber whiteness 5, a dilute acid or sour bath removes any remaining traces of metal ions and guarantees that any residual bleaching chemicals are destroyed 6, a controlled-pH freshwater final wash removes the last traces of acid and salt prior to drsdng and 7, a finish bath gives the fiber a soft handle for easy drying and subsequent processing.

Prior to the era of TNF-based perfusion, ILP was not a viable option for tumor reduction in soft-tissue sarcoma due to poor response rates. However, promising results following the introduction of high-dose TNF in ILP led to a phase II multicenter study to determine the effect of ILP with TNF and melphalan in patients with nonresectable sarcoma confined to the limb. Here the response rate was 82% with 18% complete responses. These excellent results have been confirmed by other centers. 

If we look at Eric Scerri s approach to the question of reductionism, we see that he not only rejects hard reductionism, which aims to explain all chemical phenomena in terms of quantum mechanics, but also the fallback soft position that posits an ontological dependence without demanding reduction at the level of explanation. Instead, he proposes a third option that consists in defending the autonomy of chemistry by proclaiming that the debate involves different levels of reality that are autonomous though interconnected . In particular, he emphasizes the difference between the orbitals as they are used by chemists and those dealt with by physicists working in quantum theory. Indeed, Scerri maintains that chemistry teachers should specify that the orbitals that they are talking about are not those of modern quantum mechanics. Nevertheless, it is probable that this... 

This thesis has been completely devoted to catalysis by relatively hard catalysts. When aiming at the catalysis of Diels-Alder reactions, soft catalysts are not an option. Soft catalysts tend to coordinate directly to the carbon - carbon double bonds of diene and dienophile, leading to an activation towards nucleophilic attack rather than to a Diels-Alder reaction . This is unfortunate, since in water, catalysis by hard catalysts suffers from a number of intrinsic disadvantages, which are absent for soft catalysts. 

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