tales of technetium

published in "Nature Chemistry"

The Past and Future of the Periodic Table

published in 'American Scientist' magazine

Philosophical Confusion in Chemical Education Research

published in Journal of Chemical Education

The Concept of Emergence in Systems Biology

Co-authored with Nick Tasker and Angela Matisse

A project report following a six week vacation scholarship scheme with the Department of Statistics and the Oxford Centre for Gene Function, University of Oxford, and the Bioinformatics Research Centre, University of Aarhus, headed by Professors Jotun Hein and Carsten Wiuf.

The report is not in the style of a philosophical essay. It does not deal too rigorously or thoroughly with the often well trodden and sometimes abstruse theoretical philosophical issues regarding emergence, although these are discussed to a certain extent. Rather it focuses on very practically orientated philosophical issues and is intended to be of some use to practising scientists (specifically systems biologists).

Your old men will dream dreams and your young men will see visions: The composer in old age

Irish Ageing Studies Review 2008

Jewish theology teaches that the Bible does not contain redundancies; if there are two examples of something, each should tell us something different. The Bible says (Joel, Chapter 2, Verse 28) that ‘your old men will dream dreams and your young men will see visions’.  What are dreams and visions? Are they two different things?  I think they are. 

A vision contains the idea of synthesising elements that are apparently contradictory.  A dream, on the other hand, gives us a world in which contradictory things can co-exist.  Instead of synthesising and finding a way out of contradiction by resolution dreams find a world in which contradiction can exist without conflict. 

This paper explores two major works by Beethoven: his third symphony and his last piano sonata, to contrast these two approaches to creativity.

Sex workers in Kenya, numbers of clients and associated risks: an exploratory survey.

Elmore-Meegan, M., R. M. Conroy, et al. (2004). "Sex workers in Kenya, numbers of clients and associated risks: an exploratory survey." Reprod Health Matters 12(23): 50-7.

In Kenya in 1999, an estimated 6.9% of women nationally said they had exchanged sex for money, gifts or favours in the previous year. In 2000 and 2001, in collaboration with sex workers who had formed a network of self-help groups, we conducted an exploratory survey among 475 sex workers in four rural towns and three Nairobi townships, regarding where they worked, the number of clients they had and the risks they were exposed to. Participants were identified by a network of social contacts in the seven centres. Most of the women (88%) worked from bars, hotels, bus stages and discos; 57% lived with a stable partner and almost 90% had dependent children. In the previous month, 17% had been assaulted and 35% raped by clients. Unwanted pregnancy was common; 86% had had at least one abortion. Compared with women in rural towns, township sex workers were younger (median age 22 vs. 26), saw more clients (median 9 vs. 4 per week) and earned more from sex work (up to 63-90 euros vs. 12 euros per week). Issues of alternative sources of income, safety for sex workers and the conditions which create the necessity for sex work are vital to address. The question of number of clients and the nature of sex work have obvious implications for HIV/STI prevention policy.

Golden, J., R. M. Conroy, et al. (2007). "Reliability and validity of the Hospital Anxiety and Depression Scale and the Beck Depression Inventory (Full and FastScreen scales) in detecting depression in persons with hepatitis C." J Affect Disord 100(1-3): 265-9.

BACKGROUND: We examined the performance the Beck Depression Inventory (BDI) and its short form (BDI-FS) and the Hospital Anxiety and Depression Scale depression (HADS-D) and anxiety (HADS-A) subscales in detecting depression in a group of patients with hepatitis C. METHODS: SCID-CV was used to establish DSM-IV diagnosis. Sensitivity, specificity, positive and negative predictive values were used to assess test performance and Cohen's Kappa to measure agreement with DSM diagnosis. RESULTS: Twenty-five of 88 participants had a DSM-IV depressive diagnosis. There was considerable non-overlap between 'caseness' on the BDI and HADS (Kappa=0.44). The HADS depression subscale had poor sensitivity (52%) and poor agreement with clinical diagnosis (Kappa=0.35). The full BDI had a sensitivity of 88% and a Kappa of 0.54 against a sensitivity of 84% and Kappa of 0.42 for the short form. The HADS anxiety subscale predicted depression as well as the depression subscale (sensitivity 88%, Kappa 0.47). CONCLUSIONS: Neither the BDI nor the HADS agrees well with the clinical diagnosis of depressive disorder, nor do they agree well with one another. The anxiety subscale of the HADS appears to measure depression at least as well as the depressive subscale.

Statistical theory of equations of state and phase transitions. I. Theory of condensation

JE Mayer, J. Chem. Phys. 5, 67 (1937) [CAS]; JE Mayer and Ph. G. Ackermann, J.
Chem. Phys. 5, 74 (1937) [CAS]; JE Mayer and SF Harrison, J. Chem. Phys. 6, 87,
101 (1938) [CAS]; B. Kahn and GE Uhlenbeck, Physica 5, 399 (1938) [CAS]; M.  ...

The homology of the stable non-orientable mapping class group

Algebraic & Geometric Topology 8 (2008) 1811–1832.

Combining results of Wahl, Galatius-Madsen-Tillmann-Weiss and Korkmaz one can identify the homotopy-type of the classifying space of the stable non-orientable mapping class group $N_\infty$ (after plus-construction). At odd primes $p$, the $F_p$-homology coincides with that of $Q_0(HP^\infty_+)$, but at the prime 2 the result is less clear. We identify the $F_2$-homology as a Hopf algebra in terms of the homology of well-known spaces. As an application we tabulate the integral stable homology of $N_\infty$ in degrees up to six.
As in the oriented case, not all of these cohomology classes have a geometric interpretation. We determine a polynomial subalgebra of $H^*(N_\infty ; F_2)$ consisting of geometrically-defined characteristic classes.

Ten years with the CPA (Cubic-Plus-Association) equation of state. Part 2. Cross-associating and …

In this second article of the review on the applications of the CPA
(Cubic-Plus-Association) equation of state, the focus is placed on
cross-associating systems. Various such mixtures are investigated,  ...

Novel method for estimating pure-component parameters for polymers: application to the PC-SAFT …

In this work, we develop a method for estimating pure-component parameters for
polymers for the PC-SAFT equation of state. Our method is based on pure-polymer
PVT data and extrapolating equations that relate the polymer parameters to  ...

Application of the perturbed chain SAFT equation of state to complex polymer systems using …

A simplified perturbed-chain statistical associating fluid theory (PC-SAFT)
equation of state is applied to polymer systems that include a variety of
non-associating (esters, cyclic hydrocarbons), polar (ketones) as well as  ...

Application of the CPA equation of state to glycol/hydrocarbons liquid–liquid equilibria

The Cubic Plus Association (CPA) equation of state is a thermodynamic model,
which combines the well-known cubic SRK (Soave–Redlich–Kwong) equation of
state and the association term proposed by Wertheim, typically employed in  ...

Application of the cubic-plus-association (CPA) equation of state to complex mixtures with aromatic …

The cubic-plus-association (CPA) equation of state is applied to phase
equilibria of mixtures containing alcohols, glycols, water, and aromatic or
olefinic hydrocarbons. Previously, CPA has been successfully used for  ...

Ten years with the CPA (Cubic-Plus-Association) equation of state. Part 1. Pure compounds and self- …

Application of the cubic-plus-association (CPA) equation of state to cross-associating systems

The cubic-plus-association (CPA) equation of state (EoS) is applied, using
different combining rules, to vapor−liquid equilibria (VLE) and
liquid−liquid equilibria (LLE) of alcohol−water systems. It is  ...

Prediction of liquid-liquid equilibrium for binary polymer solutions with simple activity …

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Correlation of liquid-liquid equilibria for alcohol hydrocarbon mixtures using the CPA equation of …

A recently developed equation of state, which combines the physical term of the
classical SRK EoS with the association term based on the perturbation theory of
Wertheim, called the Cubic Plus Association Equation of State (CPA EoS) ( ...

Vapor-liquid equilibria for alcohol hydrocarbon systems using the CPA Equation of state

The recently developed Cubic-Plus-Association Equation of State (CPA EoS) is
extended in this study to binary systems containing one associating compound
(alcohol) and an inert one (hydrocarbon). CPA combines the  ...

Prediction of phase equilibria in binary aqueous systems containing alkanes, cycloalkanes, and …

The cubic-plus-association (CPA) equation of state (EoS) is applied in this
study to binary aqueous mixtures containing hydrocarbons. The CPA EoS combines
the Soave−Redlich−Kwong (SRK) cubic equation of state for the physical  ...

Application of the van der Waals equation of state to polymers. I. Correlation

A reliable methodology for evaluating the energy and co-volume parameters of
cubic equations of state for polymers is proposed. Only two low-pressure
volumetric data points are used. The procedure is applied to the van der  ...

Computational and physical performance of a modified PC-SAFT equation of state for highly asymmetric …

Two modifications to perturbed-chain statistical associating fluid theory are
proposed which simplify the calculation of phase-equilibrium properties for
nonassociating and associating systems, polymers, and simple molecules  ...

Multicomponent phase equilibrium calculations for water–methanol–alkane mixtures

Prediction of phase equilibrium for multicomponent systems containing
associating compounds (eg, water and alcohols) is essential in a number of
engineering applications (eg, environmental technology, gas hydrate  ...

An equation of state for associating fluids

An equation of state (EoS) suitable for describing associating fluids is
presented. The equation combines the simplicity of a cubic equation of state
(the Soave−Redlich−Kwong), which is used for the physical part and the  ...

Fluids with highly directional attractive forces. IV. Equilibrium polymerization

We investigate approximation methods for systems of molecules interacting by
core repulsion and highly directional attraction due to several attraction
sites. The force model chosen imitates a chemical bond by providing for  ...

Fluids with highly directional attractive forces. II. Thermodynamic perturbation theory and integral …

The formalism of statistical thermodynamics developed in the preceding paper is
used as a basis for deriving tractable approximations. The system treated is one
where repulsion and highly directional attraction due to a single molecular  ...

Fluids with highly directional attractive forces. III. Multiple attraction sites

We derive a reformulation of statistical thermodynamics for fluids of molecules
which interact by highly directional attraction. The molecular model consists of
a repulsive core and several sites of very short-ranged attraction. We  ...

Fluids with highly directional attractive forces. I. Statistical thermodynamics

A new formulation of statistical thermodynamics is derived for classical fluids
of molecules that tend to associate into dimers and possibly higher s-mers due
to highly directional attraction. A breakup of the pair potential into  ...

Thermodynamic perturbation theory of polymerization

We derive several extensions of a previously given first‐order perturbation
theory (TPT 1) for fluids in which chain and ring polymers can be formed, due to
the presence of two singly bondable molecular attraction sites. We retain  ...

Equation of state for small, large, polydisperse, and associating molecules

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Equation of state for small, large, polydisperse, and associating molecules: extension to fluid …

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Heteroazeotropy and Analytical Models for Phase Equilibria

Heteroazeotropy in binary systems is of theoretical interest because it provides
a physical relation between vapor−liquid (VLE) and liquid−liquid (LLE)
equilibria. Criteria for localization of the vapor phase composition in  ...

A New Reference State for the Calculation of Activity Coefficients: Comment on the Paper “Molecular …

Volume 47, Issue 15, Page 5758. The correct definition of the partial second
virial coefficient i (given in parentheses in the text between eqs 6 and 7)
should be i = 2∑y j B ji − ∑ j ∑ i y j y i B ji . 

INTERFACIAL BEHAVIOR IN SYSTEMS TYPE IV

Prediction of Activity Coefficients at Infinite Dilution by Using the Weighted Volatility Function

Page 1. Phys. Chem. Liq., 1996, Vol. 32, pp. 1-24 Reprints available
directly from the publisher Photocopying permitted by license only 6:')
1996 OPA (Overseas Publishers Association) Amsterdam ...

Some observations regarding the prediction of isochoric heat capacities by engineering EOS models

This study evaluates the accuracy of different analytical EOS models in
predicting isochoric heat capacity experimental data, a subject that has not
received major attention so far. Contributions of the temperature  ...

Rebuttal to the Comments of Paul M. Mathias on “Unnoticed Pitfalls of Soave-Type Alpha Functions in …

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Simultaneous prediction of the critical and sub-critical phase behavior in mixtures using equations …

The present study compares the ability of two semi-predictive approaches, namely
the global phase diagram approach (GPDA) and the predictive
Soave–Redlich–Kwong model (PSRK), for describing the experimental data  ...

An accurate direct technique for parameterizing cubic equations of state Part I. Determining the …

An approach for specializing cubic equations of state to the prediction of vapor
pressures of pure fluids is presented. The method is based on a low-temperature
asymptotic approximation of the vapor–liquid equilibrium problem which,  ...

The solubility of gases in liquids

The solubility of gases in liquids is analyzed in terms of the displacements
theory, in particular the case where increasing solubility of gases is observed
for rising temperature at room pressures. Heat effects are characterized  ...

Phase behavior of Dieterici fluids

This study presents an analysis of the Dieterici equation of state using the
global phase diagram methodology. The main difference between the EOS of
Dieterici and equations of state of the van der Waals type is that  ...

Azeotropic behavior of Dieterici binary fluids

In contrast to the theoretical basis of the van der Waals model, that considers
an overall central potential to subtract cohesion forces from the hard core
contribution to pressure, the equation of state (EOS) of Dieterici [1] is  ...

An assessment of thermodynamic consistency tests for vapor-liquid equilibrium data

EQUILIBRIUM DATA CONSISTENCY TESTS FOR VAPOR-LIQUID  ... JAIME WISNIAK'.
ALEXANDER APELBLAT and HUGO SEGURA*  ... Consistene) testa are techniques tliiit
ullow. in priiiciplc. the ilssessnient ol' experimental 

Application of model-free computation techniques and limiting conditions for azeotropy. An …

The model-free computation technique of Mixon et al. is explored as a
complementary tool for the assessment of vapor-liquid equilibrium (VLE) data and
for further analysis of binary systems that satisfy standard consistency  ...

Influence of excess properties on binary liquid-liquid equilibrium

The dependence of the liquid-liquid equilibria with pressure and temperature in
noncritical ranges is analyzed and related with excess functions, particularly
excess enthalpies and volumes. It is shown that the shape of the  ...

Prediction of high-pressure phase equilibria using cubic EOS: What can be learned?

P rocess design in the high-pressure range has become an important problem in
modern industry. With the recent developments of organic chemistry, laboratories
are able to synthesize every year around 100 000 new compounds, which can  ...

Prediction of azeotropic behavior using equations of state

A shortcut method is developed to determine if an equation of state (EOS) is
capable of predicting azeotropes in binary systems and if the azeotrope meets
the critical gas-liquid equilibrium line. The method suggested allows an a  ...

Simultaneous prediction of interfacial tension and phase equilibria in binary mixtures An approach …

Vapor–liquid interfacial tensions of miscible mixtures have been predicted by
applying the gradient theory to an improved Peng–Robinson equation of state.
The modified Huron–Vidal mixing rule model has been considered for  ...

Closed loops of liquid–liquid immiscibility predicted by semi-empirical cubic equations of state …

The present study demonstrates that semi-empirical cubic EOSs, which include
temperature functionalities such as that of Soave and van der Waals classical
mixing rules, predict the behavior around the mathematical double points of  ...

Phase stability analysis in binary systems

Phys. Chem. Liq.. ZWO, Vol. 38, pp. 277-331 Reprints available directly from the
publisher Photocopying permitted by license only 0 ZWO OPA (Overseas Publishers
Association) NV Published by license under the Gordon and Breach Science  ...