Biocatalysis Fueled by Light: On the Versatile Combination of Photocatalysis and Enzymes

Enzymes catalyze a plethora of highly specific transformations under mild and environmentally benign reaction conditions. Their fascinating performances attest to high synthetic potential that is often hampered by operational obstacles such as in vitro cofactor supply and regeneration. Exploiting light and combining it with biocatalysis not only helps in overcoming these drawbacks, but the fruitful liaison of these two fields of “green chemistry” also offers opportunities to unlock new synthetic reactivities. In this review we provide an overview of the wide variety of photo-biocatalysis, ranging from the photochemical delivery of electrons required in redox biocatalysis and photochemical cofactor and reagent (re)generation to direct photoactivation of enzymes enabling reactions unknown in nature. We highlight synthetically relevant transformations such as asymmetric reactions facilitated by the combination of light as energy source and enzymes’ catalytic power.     

Current oscillations during the anodic dissolution of copper in trifluoroacetic acid

A phenomenon of current oscillators was characterized crosswise active-passive potential region during the electrodissolution of copper electrode in trifluoroacetic acid (TFA). The current density-potential curves show two transition points. A potential region of current oscillations was found as a part of limiting current region. The Cu|TFA electrochemical oscillator was found to displaying rich dynamical response on varying the temperature and the applied potential. The Cu|TFA system display current oscillation behaviour from the mono-periodic to the mixed-mode (relaxation type). Changes of the electrode surface structure and morphology were investigated by X-ray diffraction spectroscopy, atomic forced microscopy and optical microscopy.     

The influence of isosorbide on thermal properties of poly(L‐lactide) synthesized by different methods

In this article, we analyzed the influence of isosorbide content on glass transition temperature and crystallinity of poly(L ‐lactide). Different synthesis methods were applied to determine optimal procedure for polymerization of L ‐lactide in the presence of isosorbide. Two procedures were performed with tin(II) 2‐ethylhexanoate as the catalyst: first, using the vacuum sealed vessel, and second, using microwave reactor bulk polymerizations. The solution polymerization (with trifluoromethanesulfonic acid as catalyst) was possible at the temperature of 40°C. Obtained polyesters had number average molecular weights ranging from 20,000 to 65,000 g mol^–1, according to the gel permeation chromatography measurements. The polymer structure was characterized by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy. Thermal properties of the obtained polymers were analyzed using thermogravimetry (TG) and differential scanning calorimetry (DSC). According to DSC measurements, the addition of isosorbide in the polyesters influenced the increase in both glass transition temperature and degree of crystallization for all samples. The results obtained by thermogravimetric analysis confirmed the strong influence of polymerization mechanism on synthesized poly(L ‐lactides) thermal properties. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Application of fuzzy measures and interval computation to financial portfolio selection

As many data‐driven fields, finance is rich in problems requiring high computational power and intelligent systems techniques. In particular, the problem of selecting an optimal financial portfolio can be conveniently represented as a constrained optimization problem or a decision‐making problem. The aim of this paper is to show how to express the optimal portfolio selection problem from a decision‐theoretic perspective and show how to address this problem using fuzzy measures and fuzzy integrals. © 2010 Wiley Periodicals, Inc.     

The validity and reliability of the Dutch Effort–Reward Imbalance Questionnaire.

The reliability and validity of the Effort–Reward Imbalance Questionnaire were tested in 775 blue- and white-collar workers in the Netherlands. Cronbach's alpha revealed sufficient internal consistency of all subscales except Need for Control. With exploratory probabilistic scaling (Mokken) analysis, the psychometric qualities of the Need for Control scale were improved. With confirmatory factor analysis, the factorial validity of the Extrinsic Effort and Reward subscales was confirmed. A model with 3 separate dimensions for reward (status control, esteem reward, and monetary gratification) proved adequate, emphasizing the importance of distinguishing subscales. The congruent validity of the subscales and a hypothesized relationship with an external construct, health functioning, were confirmed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Wish to Leave Ethnically Concentrated Neighbourhoods: The Role of Perceived Social Cohesion and Interethnic Attitudes

This paper aims to investigate the motives behind people's wishes to move out of ethnically concentrated neighbourhoods. We focus on the impact of perceived social cohesion and negative interethnic attitudes and hypothesise on moving wishes of ethnic majority and minority residents in the Netherlands (i.e. Turks and Moroccans). Data were derived from the first wave of the 2009 Netherlands Longitudinal Lifecourse Study, collected in 35 municipalities covering 800 neighbourhoods. Taking into account household, housing and other neighbourhood attributes, multilevel logistic regression models show that ethnic majority residents are more likely to have a wish to move when they live in neighbourhoods with a large percentage of ethnic minorities. This can be explained by a lack of perceived social cohesion, but not by their negative attitudes towards ethnic minorities. Controlling for housing and neighbourhood conditions, the percentage of ethnic minorities neither increases nor decreases minority residents' moving wishes.     

Durability of different carbon nanomaterial supports with PtRu catalyst in a direct methanol fuel cell

PtRu catalysts with similar particle size and composition were deposited on three different carbon supports: Vulcan, graphitized carbon nanofibers (GNF) and few-walled carbon nanotubes (FWCNT) and their performance for methanol oxidation was studied in an electrochemical cell and in a single cell DMFC. The electrochemical results indicate that with PtRu/GNF and PtRu/FWCNT higher current densities are obtained and oxidation intermediates deactivate the surface less compared to the same catalyst on Vulcan support. Conversely, PtRu/Vulcan provided the highest open circuit voltage OCV and current densities in DMFC experiments due to a well-optimized electrode layer structure. Because stability is a key requirement for fuel cell commercialization, 6-day-long fuel cell stability tests were carried out, showing that PtRu/Vulcan degraded significantly. This was due to the collapse of the secondary structure of the electrode layer revealed by post characterization of the membrane electrode assembly (MEA) with SEM and TEM. PtRu/GNF exhibited slightly poorer initial performance but better stability because the structure of the anode layer was maintained. PtRu/FWCNT showed the worst initial performance and long-term stability. The good stability of non-optimized PtRu/GNF MEAs shows the potential of these novel nanocarbon supported catalysts as stable fuel cell components after proper MEA optimization.