Observation of surface characteristics by DSC and DTA

The three types of hydroxyl groups on surfaces of goethite crystals have previously been shown to be distinguishable by inflections on the leading edge of the dehydroxylation endotherm on DSC curves. The same inflections can be observed on DTA curves and it is now established that the main prerequisite for their observation is rapid removal of water vapour from particle surfaces, although small particle size (i.e. large surface area) and uncontaminated surfaces are also important.

---

Zusammenfassung Bei den drei Typen von Hydroxylgruppen an den Oberfläche von Goethitkristallen wurde zuvor festgestellt, daß sie durch den Wendepunkt an der Leitkante der Dehydroxylierungs-Endothermen an den DSC-Kurven zu unterscheiden sind. Dieselben Wendepunkte können auch an DTA-Kurven beobachtet werden und es steht nun fest, daß die Hauptvoraussetzung ihrer Beobachtung in der schnellen Entfernung des Wasserdampfes von der Teilchenoberfläche besteht, obwohl die kleine Teilchengrösse (d. h. eine grosse spezifische Oberfläche) und unkontaminierte Oberflächen auch von Bedeutung sind.

---

, - - . - -, . (.. ) .

---

---

The authors wish to express their sincere thanks to Mr E. L. Charsley of Stanton Redcroft Consulting Service for very kindly carrying out a determination on the STA-780 apparatus.     

The study of catalysis by novel gas chromatographic techniques

Summary Studies of catalytic reactions have been made using differential (sample-vacancy) and stopped-flow gas chromatography. Reactions are often very sensitive to trace materials and in particular it has been necessary to devise a technique for removing oxygen from carrier-gas streams down to very low levels. The techniques and the results are often relevant to the more normal analytical applications of gas chromatography.Presented at Table Ronde sur les mesures physicochimiques par chromatographie en phase gazeuse (Lyons, November 13–14th, 1973), organized by Dr.robin (INSA, Villeurbanne)     

A technique for constructing non‐embeddable quasi‐residual designs

We propose a technique for constructing two infinite families of non‐embeddable quasi‐residual designs as soon as one such design satisfying certain conditions exists. The main tools are generalized Hadamard matrices and balanced generalized weighing matrices. Starting with a specific non‐embeddable quasi‐residual 2‐(27,9,4) design, we construct for every positive integer m a non‐embeddable 2‐(3^m,3^m?1,(3^m?1?1)/2)‐design, and, if r_m=(3^m?1)/2 is a prime power, we construct for every positive integer n a non‐embeddable design. For each design in these families, a symmetric design with the corresponding parameters is known to exist. © 2002 Wiley Periodicals, Inc. J Combin Designs 10: 160–172, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/jcd.900     

Heat transport in a strongly overdoped cuprate: Fermi liquid and a pure d-wave BCS superconductor

The transport of heat and charge in the overdoped cuprate superconductor Tl(2)Ba2CuO(6+delta) was measured down to low temperature. In the normal state, obtained by applying a magnetic field greater than the upper critical field, the Wiedemann-Franz law is verified to hold perfectly. In the superconducting state, a large residual linear term is observed in the thermal conductivity, in quantitative agreement with BCS theory for a d-wave superconductor. This is compelling evidence that the electrons in overdoped cuprates form a Fermi liquid, with no indication of spin-charge separation.     

Sensitivity to disorder of the metallic state in the ruthenates

We report the results of transport measurements on SrRuO3, Sr3Ru2O7, and CaRuO3. In SrRuO3 and Sr3Ru2O7, our findings are consistent with the predictions of Fermi liquid theory, in contrast to previous reports based on samples with much shorter mean free paths. In CaRuO3, however, a T1.5 power law is seen in the resistivity in the high purity samples studied here. Our work gives concrete evidence that even the metallic state of the ruthenates is highly sensitive to disorder.     

The Fire/Heat Concept and Its Journey from Prehistoric Time into the Third Millennium

The notion of fire/light/heat/energy is recognized as an integrating element in the pathway of ordering matter and society, and its historical aspects are thoroughly reviewed. Fire is argued to be a philosophical archetype and its role in the early concept of four elements is discussed. The Indian, Arabic and Greek historical bases are mentioned. Alchemy is briefly reviewed as a source of the wider adoption of fire. The era of renaissance and the new age are also included. The message of fire/heat is nowadays focused on the progress of civilization, with the assumption of engines as information transducers based on the conscious exploitation of fire. The role of chaos is emphasized. Overall, a condensed but consistent view is given of the various concepts that emerged during the historical progress of the understanding of heat (noting 61 references). This revised version was published online in July 2006 with corrections to the Cover Date.     

Generalized stress/strain rate relations for creep of thin shells; a comparison of “exact” and approximate relations

A set of approximate generalized stress/strain rate relations which has been used for the stationary creep analysis of thin shells is compared with the corresponding ‘exact’ relations. The comparison is made by computing the functions from which the relations are derived and plotting the corresponding surfaces. Results are included for a limiting condition in which the stress/strain rate relations become those for a rigid-plastic material obeying the von Mises yield condition and associated flow rule. Although the comparison is made only for conditions valid in a cylindrical shell under rotationally symmetric loading, it indicates the errors which are likely to occur when the approximate relations are used in stationary creep analysis.     

Following radical pair reactions in solution: a step change in sensitivity using cavity ring-down detection

The study of radical pair intermediates in biological systems has been hampered by the low sensitivity of the optical techniques usually employed to investigate these highly reactive species. Understanding the physical principles governing the spin-selective and magneto-sensitive yields and kinetics of their reactions is essential in identifying the mechanism governing bird migration, and might have significance in the discussion of potential health hazards of electromagnetic radiation. Here, we demonstrate the powerful capabilities of optical cavity-enhanced techniques, such as cavity ring-down spectroscopy (CRDS) in monitoring radical recombination reactions and associated magnetic field effects (MFEs). These include submicrosecond time-resolution, high sensitivity (baseline noise on the order of 10(-6) absorbance units) and small (μL) sample volumes. Combined, we show that these represent significant advantages over the single-pass flash-photolysis techniques conventionally applied. The studies described here focus on photoinduced radical pair reactions involving the protein lysozyme and one of two possible photosensitizers: anthraquinone-2,6-disulphonate and flavin mononucleotide. CRDS-measured MFEs are observed in pump-probe experiments and discussed in terms of the sensitivity gains and sample-volume minimization afforded by CRDS when compared with flash photolysis methods. Finally, CRDS is applied to an in vitro MFE study of intramolecular electron transfer in the DNA-repair enzyme, Escherichia coli photolyase, a protein closely related to cryptochrome which has been proposed to mediate animal magnetoreception.     

Intramolecular 2h group-transfer in heterocyclic bridged-ring systems (dyotropic rearrangements)

Diarylnitrilimines, derived by thermolysis of appropriate diaryltetrazoles, form(4+2)π cyclo-adducts with dipolarophiles of the isodrin type, e.g. $\text{(1)}$; the resulting 2-pyrazolines thermally rearrange into pyrazoles by hydrogen group transfer. Kinetic data for examples of this and related reactions are reported.