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To the Editor: It was great to see the diesel engine finally getting noticed in what overall was a nice article, 'A New Dawn for Diesel,' in the January issue, [...]

The advantages of designing heat exchangers in the laminar-flow regime are discussed from a theoretical standpoint. It is argued that laminar-flow designs have the advantages of reducing thermodynamic and hydrodynamic irreversibilities, and hence increasing system efficiency. More concretely, laminar-flow heat exchangers are free from the turbulence-induced vibration common in conventional heat exchangers, and can thus offer longer life and greater reliability.The problems of manufacturing heat exchangers suited to laminar flow are discussed. A method of manufacture is outlined that allows compact, modular design. Experience with this method of manufacture is described. Experimental results with a prototype heat exchanger bank are presented; these results show good agreement with theory at moderate levels of effectiveness (75-85%), but fall below predicted values at higher levels. It is argued that this discrepancy results from flow maldistribution. The problems of fouling and flow maldistribution are briefly discussed, and some possible applications are mentioned.

Various issues affecting nuclear magnetic resonance probe resolution are discussed, with emphasis on high-resolution or magic angle spinning (MAS) in this part. Symmetric positioning of chip capacitors at the magic angles addresses the largest B0 perturbation with ultra-low-inductance decoupling coils, and symmetric spinner drive designs with silicon-nitride coilforms are shown to be extremely beneficial in reducing spinning-, decoupling-, and variable temperature-induced thermal gradients. Other factors discussed include MAS sample cell design, high frequency (HF) coils, centrifugation, shimming, B1 homogeneity, B0 stability, and geometric compensation for variable angle spinning resolution. ©1998 John Wiley & Sons, Inc. Concepts Magn Reson 10: 239–260, 1998

In Part I, we review some basic physics, properties, and types of magnetism as they relate to high-resolution nuclear magnetic resonance (NMR) probe design, both in liquids and in solids, and some of the reasons it is technically difficult to obtain resolution of several parts per billion. We note the beneficial attributes of elliptical symmetries and the finite magic angle cylinder; and some methods of calculating fields produced by various objects are reviewed, with emphasis on the method of effective surface currents. Using a novel dual-ring method, the high-field magnetic properties of various materials important to NMR probe construction are obtained. Methods of adjusting and controlling the susceptibility of special adhesives, wire, foil, and dewar alloys are discussed. In Part II, we will look more specifically at high-resolution magic angle spinning probe design issues. ©1998 John Wiley & Sons, Inc. Concepts Magn Reson 10: 133–156, 1998

•Spline horns are better than corrugated for converting TE11 to HE11 in waveguides•Smooth downtapers work as well as corrugated in small overmoded waveguides•Losses in short corrugated waveguides are much greater than has been predicted•Perfect smooth waveguides with downtapers perform well but are vulnerable to defects•Dielectric linings and lenses are only helpful in short waveguides

No abstract.

Presents a letter to the editor in response to the article "A Second Look at Nuclear Power," by Paul Lorenzini in the spring 2005 issue.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

No abstract.