Thin-layer chromatography of pigments from reaction center particles of Rhodopseudomonas spheroides

1. Pigments extracted from reaction center particles of Rhodopseudomonas spheroides were separated and identified by means of thin-layer chromatography.\ud \ud 2. The results strongly suggest that bacteriochlorophyll a is the only bacteriochlorophyll pigment present in reaction centers.\ud \ud 3. Other compounds identified are bacteriopheophytin a, ubiquinone-10 and spheroidene

Modelling survival and connectivity of Mnemiopsis leidyi in the south-western North Sea and Scheldt estuaries

Three different models were applied to study the reproduction, survival and dispersal of Mnemiopsis leidyi in the Scheldt estuaries and the southern North Sea: a high-resolution particle tracking model with passive particles, a low-resolution particle tracking model with a reproduction model coupled to a biogeochemical model, and a dynamic energy budget (DEB) model. The results of the models, each with its strengths and weaknesses, suggest the following conceptual situation: (i) the estuaries possess enough retention capability to keep an overwintering population, and enough exchange with coastal waters of the North Sea to seed offshore populations; (ii) M. leidyi can survive in the North Sea, and be transported over considerable distances, thus facilitating connectivity between coastal embayments; (iii) under current climatic conditions, M. leidyi may not be able to reproduce in large numbers in coastal and offshore waters of the North Sea, but this may change with global warming; however, this result is subject to substantial uncertainty. Further quantitative observational work is needed on the effects of temperature, salinity and food availability on reproduction and on mortality at different life stages to improve models such as used here

Giant coronary aneurysms: three-dimensional reconstruction

A 31 year old man was referred for the evaluation of chest pain. Cardiac CT reconstruction revealed multiple calcified giant coronary aneurysms. Most likely this patient suffered from subclinical Kawasaki’s disease in his childhood

Partial nonlinear reciprocity breaking through ultrafast dynamics in a random photonic medium

We demonstrate that ultrafast nonlinear dynamics gives rise to reciprocity breaking in a random photonic medium. Reciprocity breaking is observed via the suppression of coherent backscattering, a manifestation of weak localization of light. The effect is observed in a pump-probe configuration where the pump induces an ultrafast step-change of the refractive index during the dwell time of the probe light in the material. The dynamical suppression of coherent backscattering is reproduced well by a multiple scattering Monte Carlo simulation. Ultrafast reciprocity breaking provides a distinct mechanism in nonlinear optical media which opens up avenues for the active manipulation of mesoscopic transport, random lasers, and photon localization.Comment: 5 pages, 4 figure

Backward Erosion Piping Model Verification Using Cases in China and The Netherlands

Backward erosion piping, the process of shallow pipe development in the sandy foundation of levees, is a threat to the safety of levees in countries like China and the Netherlands. Several models are available to predict the required critical head for this phenomenon, i.e. Bligh’s model and Sellmeijer’s model. Well-documented breach cases, which unfortunately are rare, give the opportunity to verify the applicability of prediction models. In this paper two piping cases in China and one piping case in the Netherlands have been described and analyzed in order to compare the outcome of prediction models with this actual data. It is concluded that Bligh’s model is easy to apply due to a small number of input parameters. The use of this model as a first step in safety assessment is limited due to the fact that it can give lower critical head predictions than the more accurate Sellmeijer model. On the other hand, the Sellmeijer model is more difficult to apply due to its sensitivity to permeability and grain size parameters. This sensitively results in a wide range for the critical head due to large uncertainties in the parameters. A probabilistic approach for parameter estimation combined with a more detailed soil investigation where necessary is recommended for a more accurate piping prediction

Systemic and white adipose tissue inflammation in obesity and insulin resistance

As the obesity epidemic is still increasing, strategies to prevent and treat obesity and related pathologies are in great demand. Obesity-induced inflammation is thought to contribute to the development of metabolic disorders. Therefore, inflammatory pathways that play a role in obesity-induced inflammation are potential promising targets in the treatment of metabolic disorders. Extensive knowledge on obesity-induced inflammation and the role of inflammatory pathways in the development of metabolic disorders can benefit the development of these therapeutic strategies. Mouse models are widely used to study obesity and related disorders, however, to what extent mouse-derived results translate to humans has not been studied extensively yet. Obesity-induced inflammation and its role in the development of insulin resistance, as well as the similarities of these processes between humans and mice, have been addressed in this thesis. The new findings described in this thesis will be summarized and discussed in the final chapter. Additionally, clinical implications of obesity-induced inflammation as target to treat metabolic disorders and future perspectives will be addressed.LUMC / Geneeskund

Standards-Based Assessment in a Developmental Math Course

Learn why we decided to try standards-based instruction in an undergraduate, developmental algebra course and what we learned in the process

Structure-Based Redesign of a Self-Sufficient Flavin-Containing Monooxygenase towards Indigo Production

Indigo is currently produced by a century-old petrochemical-based process, therefore it is highly attractive to develop a more environmentally benign and efficient biotechnological process to produce this timeless dye. Flavin-containing monooxygenases (FMOs) are able to oxidize a wide variety of substrates. In this paper we show that the bacterial mFMO can be adapted to improve its ability to convert indole into indigo. The improvement was achieved by a combination of computational and structure-inspired enzyme redesign. We showed that the thermostability and the kcat for indole could be improved 1.5-fold by screening a relatively small number of enzyme mutants. This project not only resulted in an improved biocatalyst but also provided an improved understanding of the structural elements that determine the activity of mFMO and provides hints for further improvement of the monooxygenase as biocatalyst.</p