Rubber elasticity in the introductory thermodynamics course

An experimental set-up is described in which the temperature of a piece of rubber is measured with thin wire thermocouples. It measures and records the temperature change of the rubber as it heats and cools in response to elongation and contraction. This mechano-caloric effect arising from the entropy elasticity of rubber represents a reversible thermal process in clear distinction from most of other heat effects encountered in our daily experience where the irreversibility is inevitably involved. The demonstration experiment has been proved useful in elementary thermodynamic courses for introducing the entropy concept. This revised version was published online in August 2006 with corrections to the Cover Date.     

Enantiomer systems of carnitinamide inorganic salts: introductory studies to a successful entrainment resolution

The ready availability of (R)-carnitinamide, an immediate synthetic precursor of (R)-carnitine, is an ambitious goal and resolutions, due to the very low cost of racemic carnitinamide, can be the most convenient technology to achieve it. Before developing a new advantageous resolution of carnitinamide chloride by entrainment, we characterized the enantiomer systems formed by the chloride, nitrate and sulfate of carnitinamide, mainly by DSC and IR analyses, proving that a different type of racemate is produced by each of these salts: a conglomerate by the chloride, a racemic compound by the nitrate and a solid solution, a very rare type of enantiomer system, by the sulfate.     

The Australian perspective

This presentation deals with issues of comparability and traceability in food analysis in Australia from several perspectives. This includes the current national (Australian) and increasingly international (Codex) performance-based approach to food analysis. The Australian food regulatory process will be described, particularly those aspects that impact on the analysis of food in a regulatory sense. This section will also describe two areas where specific methods have been mandated in legislation and discuss two case studies where the analytical method has impacted on the elaboration of standards. Other areas to be covered include regulation/requirements relating to supply/availability of reference materials, the use of proficiency testing as a means of ensuring comparability, and, finally, some thoughts on what role BIPM/CCQM may play in the analysis of food.Electronic Supplementary Material  Supplementary material is available for this article at

Traceability in perspective

Results that reference SI units rarely pose problems in chemical measurement because traceable standards, with uncertainties derived from a chain of calibrations from the SI, are readily available at the analyst??s bench. These uncertainties are nearly always far smaller than that required for fitness for purpose in the analytical result. Moreover, the greater part of the uncertainty in a typical result is not derived from primary measurements traceable to the SI but from recovery problems and matrix effects. Even so, the incidence of wildly inaccurate results stems not from this uncertainty but from ??blunders??, deviations from the correct procedure. Attention to traceability beyond that employed by any competent analyst therefore cannot reduce the uncertainty. Furthermore, there is no rational reason to reduce the uncertainty if the result is already fit for purpose. The current focus on traceability is distracting analysts from the more pressing task of eliminating blunders.     

Sports drug testing--an analyst's perspective

Sport plays a major role in the lives of many people, both for active participation and as entertainment. Sport is now a huge nationally and internationally based industry. The desire to win has led some athletes to resort to the use of performance enhancing drugs. With huge financial rewards now available in some sports the pressure to excel has grown. Some have argued that drug use should be given free rein, however most people are of the view that it is athletic prowess that should be applauded not the efficacy of various performance enhancing drugs. Apart from the obvious aspects of equality and fair play, the use of drugs is associated with significant health risks. In the 1960's the use of stimulants in sports such as cycling led to the death of at least one cyclist. Since 1968 the International Olympic Committee (IOC) has required all Olympic Games' host cities to provide laboratory facilities for the analysis and detection of performance enhancing drugs. There are now 29 IOC accredited laboratories throughout the world that routinely test samples from athletes for the presence of such drugs. The purpose of this tutorial review is to give an overview of drug testing procedures, including those that were used at the last summer Olympic Games in Sydney 2000, and the incorporation of the latest developments in analytical chemistry technology in the drug testing process. More recently, developments in biotechnology mean that the use of whole new classes of drugs are banned in sport, often requiring new methodologies and techniques for their analysis. The contest between those who wish to cheat and those who wish to maintain fair play in sport is an ongoing one.     

Pressure amorphized ices--an atomistic perspective

We offer our viewpoint on the nature of amorphous ices produced by pressurization of crystalline ice Ih and the inter-relationship between them from an atomistic perspective. We argue that the transformation of high density amorphous (HDA) ice from crystalline ice is due to a mechanical process arising from the instability of the ice Ih structure. The densification of HDA upon thermal annealing under pressure is a relaxation process. The conversion of the densified amorphous ice to a lower density form (LDA) upon the release of pressure can be attributed to a similar process. It is speculated that amorphous ices are metastable frustrated structures due to the large activation barriers associated with proton reorientation in the formation of the underlying stable crystalline ice polymorphs.     

Quantum crystallography: A perspective

Extraction of the complete quantum mechanics from X‐ray scattering data is the ultimate goal of quantum crystallography. This article delivers a perspective for that possibility. It is desirable to have a method for the conversion of X‐ray diffraction data into an electron density that reflects the antisymmetry of an N‐electron wave function. A formalism for this was developed early on for the determination of a constrained idempotent one‐body density matrix. The formalism ensures pure‐state N‐representability in the single determinant sense. Applications to crystals show that quantum mechanical density matrices of large molecules can be extracted from X‐ray scattering data by implementing a fragmentation method termed the kernel energy method (KEM). It is shown how KEM can be used within the context of quantum crystallography to derive quantum mechanical properties of biological molecules (with low data‐to‐parameters ratio). © 2017 Wiley Periodicals, Inc.     

Complex II from a structural perspective

The super-macromolecular complex, succinate:quinone oxidoreductase (SQR, Complex II, succinate dehydrogenase) couples the oxidation of succinate in the matrix / cytoplasm to the reduction of quinone in the membrane. This function directly connects the Krebs cycle and the aerobic respiratory chain. Until the recent first report of the structure of SQR from Escherichia coli (E. coli) the structure-function relationships in SQR have been inferred from the structures of the homologous QFR, which catalyses the same reaction in the opposite direction. The structure of SQR from E. coli, analogous to the mitochondrial respiratory Complex II, has provided new insight into SQR's molecular design and mechanism, revealing the electron transport pathway through the enzyme. Comparison of the structures of SQR, QFR and other related flavoproteins shows how common amino acid residues at the interface of two domains facilitate the inter-conversion of succinate and fumarate. Additionally, the structure has provided a possible explanation as to why certain organisms utilise both SQR and QFR despite the fact that both can catalyse the inter-conversion of succinate and fumarate, in vitro and in vivo. Here we review how this structure has advanced our knowledge of this important enzyme and compare the structural information to other members of the Complex II superfamily and related flavoproteins.     

Zeolite synthesis: an energetic perspective

Taking |D(H(2)O)(x)|[AlSiO(4)] based materials (where D is Li, Na, K, Rb or Cs) as an archetypal aluminosilicate system, we use accurate density functional theory calculations to demonstrate how the substitution of silicon cations in silica, with pairs of aluminium and (alkali metal) cations, changes the energetic ordering of different competing structure-types. For large alkali metal cations we further show that the formation of porous aluminosilicate structures, the so-called zeolites, is energetically favored. These findings unequivocally demonstrate that zeolites can be energetic preferred reaction products, rather than being kinetically determined, and that the size of the (hydrated) cations in the pore, be it inorganic or organic, is critical for directing zeolite synthesis.     

Bryozoan metabolites: an ecological perspective

This Highlight covers the chemical ecology of bryozoans, primarily the ecological functions of bryozoan natural products. The Highlight is arranged taxonomically, according to the bryozoan Treatise classification (P. Bock, Bryozoa Homepage, 2006, http://bryozoa.net).     

A perspective on the Li-ion battery

<正>In the 1960s,Rouxel in France and Robert Schroeder in Germany explored the chemistry of reversible intercalation of Li~+between MS_2 (M=transition metal) layers held together by weak Van der Waals bonding [1].In 1967,Kummer and Webber of the Ford Motor Co.had discovered fast2D Na~+diffusion at 300℃in incompletely occupied Na and O layers between spinel blocks of an aluminum oxide and had invented a sodium-sulfur battery operating above300℃.Their cell had molten sodium as the negative electrode (anode) and carbon felt in molten sulfur as the positive electrode (cathode)[2];the molten electrodes were separated