Achilles’ heel

Removing decay heat has been the "Achilles Heel" of nuclear power. The designs shown in this section use active methods to remove the heat, (a) Sketch and discuss a design that removes the heat passively, (b) It would seem that the energy in the decay heat could be used for its own removal. Sketch and discuss a design that uses this property to remove the decay heat. 

Broecker, W. S. (1997). Thermohaline circulation, the Achilles heel of our climate system Will man-made CO2 upset the current balance Science 278, 1582-1588. 

The weak spots, or Achilles heels, of the body occur where the skin ends and mucous epithelial tissues begin (mouth, anus, eyes, ears, nose and urinogenital tract). These mucous membranes present a much more favourable environment for microbial growth than the skin, in that they are warm, moist and rich in nutrients. Such membranes. 

The Achilles heel of two-dimensional TLC is the difficulty recording and quantifying chromatograms. 

In ICP-AES and ICP-MS, sample mineralisation is the Achilles heel. Sample introduction systems for ICP-AES are numerous gas-phase introduction, pneumatic nebulisation (PN), direct-injection nebulisation (DIN), thermal spray, ultrasonic nebulisation (USN), electrothermal vaporisation (ETV) (furnace, cup, filament), hydride generation, electroerosion, laser ablation and direct sample insertion. Atomisation is an essential process in many fields where a dispersion of liquid particles in a gas is required. Pneumatic nebulisation is most commonly used in conjunction with a spray chamber that serves as a droplet separator, allowing droplets with average diameters of typically <10 xm to pass and enter the ICP. Spray chambers, which reduce solvent load and deal with coarse aerosols, should be as small as possible (micro-nebulisation [177]). Direct injection in the plasma torch is feasible [178]. Ultrasonic atomisers are designed to specifically operate from a vibrational energy source [179]. 

This brief anecdote should serve to illustrate that its extensively interdisciplinary character is not only a strength of bio-EPR but also its Achilles heel. When the production of significant results requires comparable input efforts from different disciplines, there is an increased chance for the occurrence of time-wasting misunderstandings and errors. A less anecdotic example is the claim—frequently found in physics texts—that sensitivity of an EPR spectrometer increases with increasing microwave frequency. Although this statement may in fact be true for very specific boundary conditions—for example, when sensitivity stands for absolute sensitivity of low-loss samples of very small dimensions—when applied in the EPR of biological systems it can easily lead to considerable loss of time and money and to frustration on the part of the life science researcher, because it is simply not true at all for (frozen) solutions of biomolecules. 

How do we know or decide what terms to put in the spin Hamiltonian This is a question of rather far-reaching importance because, since we look at our biomolecular systems through the framework of the spin Hamiltonian, our initial choice very much determines the quality limits of our final results. In other branches of spectroscopy this is sometimes referred to as a sporting activity. We are guided (one would hope) by a fine balance of intellectual inspection, (bio)chemical intuition, and practical considerations. In a more hypochondriacal vein, one could also call this the Achilles heel of the spectroscopy a wrong choice of the model (the spin Hamiltonian) will not lead to an accurate description of nature represented by the paramagnetic biomolecule. 

It is well known (e.g. [77, 78]) that the prediction of reaction barrier heights is one of the main Achilles heels of density functional theory. For instance [79], for the prototype Sn2 reaction,... 

Taylor, P. J. Matrix effects the Achilles heel of quantitative high-performance liquid chromatography-electrospray-tandem mass spectrometry. Clin Biochem 2005, 38, 328-334. 

NOTE The grinding steps are the Achilles heel of this operation. The heatgenerated by grinding can easily deactivate the toxin. An air grinder was developed that eliminated this problem and may be available commercially. For best results the ricin should be as fine as possible. 

Persistent BZD dependence syndrome (PBDS) is a physiological state that is not pathological but the normal consequence of the pharmacological effects of BZDs prescribed for therapeutic objectives. It does not produce irreversible physical or psychiatric harm, and it is the Achilles heel of long-term BZD therapy. This alleged syndrome has been described only in anecdotal reports, with patients typically reporting withdrawal symptoms not present during or before BZD treatment that persist for many months or years after treatment is stopped. Jable 12-11 illustrates the major differences between persistent PBDS and BPWS. 

NER, a highly versatile pathway for DNA damage removal, is often dysfunctional in NSCLC and might therefore be the Achilles heel for customizing chemotherapy. NER removes numerous types of DNA helix-distorting lesions, including cisplatin- and ultraviolet-induced photo products (12). 

These contributions were taken explicitly to a quantum mechanical level by Levich during the 1960s and then by Schmickler, who finally published an elegant summary of quantum electrode kinetics in 1996. Schmickler stressed the quantum mechanical formulation made by Levich, Dogonadze, and Kuznetsov. However, his summary of the quantum mechanical formulation of electrode reactions still possesses the Achilles heel of earlier formulations it is restricted to nonbond-breaking, seldom-occurring outer-sphere reactions and involves the harmonic approximation for the energy variation, which is the main reason of such theories cannot replicate Tafel s law (Khan and Sidik, 1997). 

Conversion of the carboxyl group to a more reactive group and coupling are key steps in peptide synthesis. The coupling reaction must occur readily and quantitatively, and with a minimum of racemization of the chiral centers in the molecule. This last criterion is the Achilles heel of many possible coupling sequences. The importance of nonracemization can best be appreciated by an example. Consider synthesis of a tripeptide from three protected... 

For Further Reading C. Baird, Environmental Chemistry (New York W. H. Freeman and Company, 1995), pp. 13-76. R. Monastersky, Drop in ozone killers means global gain, Science News, Mar. 9, 1996, p. 151. The Royal Swedish Academy of Sciences, Press Release The 1995 Nobel Prize in Chemistry The ozone layer—the Achilles heel of the biosphere, http /Avww.nobel.se/laureates/chemistry-1995-press.html)... 

Despite the various claims which have been made for the preparation of stable polyacetylenes it is worth emphasising that stability is a relative property. It is our opinion that there has been no clear demonstration of a polyacetylene stable in air at even modestly elevated temperatures for more than a few days and that stability remains the Achilles heel of this particular polymer. 

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