Metrology and protometrology: the ordinal question

Laboratory medicine provides results for quantities as well as for properties having no magnitude. The terminology of the latter is less well established and sources are contradictory. Two recent papers on “protometrology” published in this journal offer an opportunity to discuss the necessary concept systems. The delineations of “metrology” versus “protometrology”, “observation” versus “measurement”, and the generic division of “property” are examined with emphasis on avoiding conflict with the International Vocabulary of Metrology. It is suggested that having “examination” as a top generic concept coupled with systematic modifiers for division, especially ‘nominal’ and ‘ordinal’, is a preferable terminological solution.

In defence of the correlation coefficient

The relationship between calibrated range, residual standard deviation and correlation coefficient r is discussed. It is shown that in typical chemical calibration applications with appropriately distributed calibration points (particularly, with range comparable to mean and with approximately even or with ‘successive dilution’ spacing), the linear correlation coefficient has valid application as a routine criterion for acceptable fit if used with due care.

Structural formulas and explanation in organic chemistry

Organic chemists have been able to develop a robust, theoretical understanding of the phenomena they study; however, the primary theoretical devices employed in this field are not mathematical equations or laws, as is the case in most other physical sciences. Instead it is diagrams, and in particular structural formulas and potential energy diagrams, that carry the explanatory weight in the discipline. To understand how this is so, it is necessary to investigate both the nature of the diagrams employed in organic chemistry and how these diagrams are used in the explanations of the discipline. I will begin this paper by characterizing some of the major ways that structural formulas used in organic chemistry. Next I will present a model of the explanations in organic chemistry and describe how both structural formulas and potential energy diagrams contribute to these explanations. This will be followed by several examples that support my abstract account of the role of diagrams in the explanations of organic chemistry. In particular, I will consider both the appeal to ‘hyperconjugation’ in the explanation of alkene stability and how the idea of ‘ring strain’ was developed to explain the relative stability of cyclic compounds.

Hermann Jahn and Rudolf Renner of the Jahn–Teller and Renner–Teller effects

Vibronic interactions have received increasing attention in modern structural chemistry. Edward Teller played a pioneering role in understanding and describing them during the “molecular physics” period of his scientific career. Very little is known about the two scientists who contributed significantly to our knowledge about these effects and whose names have become associated with Teller’s. This Editorial is devoted to Hermann Jahn and Rudolf Renner and attempts to lift them out of oblivion by paying them tribute for their contributions.

Paneth, Kant, and the philosophy of chemistry

Immanuel Kant has built up a dualistic epistemology that seems to fit to the peculiarities of chemistry quite well. Friedrich Paneth used Kant’s concept and characterised simple and basic substances which refer to the empirical and to the transcendental world, respectively. This paper takes account of the Kantian influences in Paneth’s philosophy of chemistry, and discusses pertinent topics, like observables, atomism and realism.

A novel Ce<Superscript>III</Superscript>-cyclam type complex and its redox chemistry in aqueous solutions

A new Ce^III complex was synthesized by mixing the ligand “dioxocyclam” with Ce^III ions at pH 8.0 and its redox properties were investigated.

A note on Michael Weisberg’s: challenges to the structural conception of chemical bonding

Michael Weisberg’s recent 2007 paper on the chemical bond makes the claim that the chemical notion of the covalent bond is in trouble. This note casts doubts on that claim.

Operating ‘cost’ characteristics in sampling by variable and attribute

A discussion in economic terms of common rules in conformity assessment based on measurement is given. The present work extends tools of sampling when using inspection by variable and attribute, such as the setting of acceptance quality limits (AQL) and limiting quality limits (LQL), by including an economic decision theory approach, leading, amongst other things, to a new ‘cost’ curve as a complement to the traditional operating characteristic curves of statistical significance testing. The methodology is of general applicability but is illustrated in the present work in the simple case of homogeneously pre-packaged goods priced linearly with the amount of content. The relation to the optimised uncertainty methodology is explained. Optimum strategies for the supplier are illustrated in terms of minimising production and testing costs, while at the same time maintaining satisfactory levels of customer satisfaction.

Interaction force diagrams: new insight into ligand-receptor binding

A method is described to calculate and visualize the interaction forces of ligand-receptor complexes. Starting from an X-ray crystallographic structure, a “thawing” procedure results in a force-field energy-minimized geometry which is close to the crystallographic starting point. By subtracting non-bonded interactions of the ligand with each amino acid residue and using the resulting force vectors to describe the slope of the remaining potential, two types of interaction force diagrams are created; the first shows the direction of the force vectors in 3D and the second shows the magnitude of the force vectors. The latter representation leads to definition of an ‘Interaction Force Fingerprint’ (IFFP) which is characteristic of the ligand-receptor binding. IFFPs are used to discuss ligand binding in the human estrogen receptors ERα and ERβ, and provide new insight into ligand selectivity between receptor isoforms. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.

The meaning of ‘concentration’

Terminology within a small laboratory community can be informal without danger of misunderstanding, but communication with a wider audience and not least in publications, needs unequivocal terms for defined concepts. As an example, the many meanings of “concentration” are explored to present a systematic nomenclature, including a concept diagram.

Structure and chromotropic properties of mono- and binuclear mixed-ligand nickel(II) complexes containing 1,3-diketonate and polyamine ligands

Abstract  Mixed-ligand Ni^II complexes have been synthesized with 1,3-diketonate and bulky tri- or tetra-amine ligands. Their structures were determined by X-ray crystallography, and solvatochromic behavior was examined by UV–vis–NIR spectroscopy. Steric effects of the bulky ligands on the coordination distances and spectral properties are discussed. Graphical Abstract  

Preparation, structural, and optical features of two-dimensional cross-linked DNA/gold-nanoparticle conjugates

The formation and the optical features of two-dimensional aggregates formed by DNA-directed immobilization and cross-linking of bifunctional DNA–gold nanoparticles at flat gold substrates are analyzed. The samples are structurally characterized by atomic force microscopy to evaluate the particle size, the particle densities, and the degree of aggregation. The optical characteristics determined by UV/visible measurements are correlated with the structural features observed.

Encapsulating of single quantum dots into polymer particles

Single semiconductor quantum dots were embedded into polymer particles with diameters below 0.1 μm by an emulsion polymerization procedure or via a secondary dispersion approach. The photoluminescence properties of the nanocrystals are retained upon encapsulation, as demonstrated by fluorescence confocal microscopy.

Why take chemistry stoically? The case of Posidonius

This paper analyzes views of the Stoic philosopher Posidonius (1st century BC) in the light of modern Chemistry. I propose that Posidonius’ account on “generation and destruction” bears noteworthy similarities to the scientific notions of chemical elements, chemical species, nuclear reactions, and the law of conservation of mass. I find that his views compare favorably also with our understanding of chemical change at solid surfaces. Provided his thought is correctly placed in the cultural context of his day, I argue that Posidonius deserves a previously un-acknowledged consideration in the historical background of modern Chemistry.

Wilhelm Ostwald’s energetics 3: energetic theory and applications,part II

This is the third of a series of essays on the development and reception of Wilhelm Ostwald’s energetics. The first essay described the chemical origins of Ostwald’s interest in the energy concept and his motivations for seeking a comprehensive science of energy. The second essay and the present one discuss his various attempts, beginning in 1891 and extending over almost 3 years, to develop a consistent and coherent energetic theory. A final essay will consider reactions to this work and Ostwald’s replies, and will also seek to evaluate his program of research. Ostwald’s project—to reconstruct physics and chemistry “as a pure energetics”—is worth attending to for several reasons: first, because Ostwald did ground-breaking work in chemistry (he was awarded a Nobel Prize in 1909 for his studies in catalysis and rates of reaction); second, because an important school of physical chemistry formed around him at Leipzig, a school that promoted his ideas; and, finally, because he was a prominent and vigorous participant in debates at the end of the nineteenth century concerning the proper course of physical theory.

Vocabulary of terms in protometrology

Protometrology is a new term recently proposed to designate the science of observation. As any field of knowledge needs a terminological system, in this article a system of terms and definitions on protometrology, with examples belonging to clinical laboratory sciences, is presented. This terminological system starts with the definitions of the two primitive concepts “object” and “property”.

Update on COMAR: the Internet database for certified reference materials

This paper describes the COMAR database for certified reference materials (CRMs). The Web-based version of COMAR is freely accessible via the Internet. COMAR was established to assist laboratories in finding the CRMs needed. The database is maintained in a collaboration of the world’s major CRM producers. The planned changes in the database as agreed at the last COMAR council meeting in Prague in May 2006 are indicated.

On the open-circuit interaction between methanol and oxidized platinum electrodes

In the present work, results of the interaction between methanol and oxidized platinum surfaces as studied via transients of open-circuit potentials are presented. The surface oxidation before the exposure to interaction with 0.5 M methanol was performed at different polarization times at 1.4 V vs reversible hydrogen electrode (RHE). In spite of the small changes in the initial oxide content, the increase of the pre-polarization time induces a considerable increase of the time needed for the oxide consumption during its interaction with methanol. The influence of the identity of the chemisorbing anion on the transients was also investigated in the following media: 0.1 M HClO₄, 0.5 M H₂SO₄, and 0.5 M H₂SO₄ + 0.1 mM Cl⁻. It was observed that the transient time increases with the energy of anion chemisorption and, more importantly, without a change in the shape of the transient, meaning that free platinum sites are available at the topmost layer all over the transient and not only in the potential region of small oxide ‘coverage’. The impact of the pre-polarization time and the effect of anion chemisorption on the transients are rationalized in terms of the presence of surface and subsurface oxygen driven by place exchange.

The Physical and Electronic Structure of M<Subscript>2</Subscript> Quadruply Bonded Complexes: A Density Functional Theory Study

The electronic structures and the physical properties (vertical excitation energies, vibrational stretching frequencies, and bond lengths) of a variety of M–M quadruply bonded (M = Mo, W) complexes are investigated using density functional theory (DFT). By utilizing a variety of pure and hybrid exchange-correlation (XC) functionals and a number basis sets, we are able to recommend a theoretical methodology for most efficiently probing the electronic structures of homoleptic M₂(O₂CR)₄ and bridged M₂(O₂C-X-CO₂)M₂ (R = organic group, typically H; X = conjugated organic group) complexes.