LEDs based on conjugated PPV block copolymers

A way to control the bandgap in semi-conducting polymers is by preparing polymers with a partially conjugated backbone. In our laboratory, three conjugated copolymers containing PPV trimers as light emitting chromophores have been synthesized, which emit in the blue, green and orange wavelength region. The copolymers have a well defined conjugated backbone consisting of regularly alternating terphenylene and p-phenylene-vinylene blocks. The desired control of conjugation length is achieved through steric interaction induced by the side-chains in the terphenyl blocks of the copolymer. In this paper we evaluate the electrical and optical properties of LED devices based on these conjugated PPV block copolymers

Amphotericin forms an extramembranous and fungicidal sterol sponge.

For over 50 years, amphotericin has remained the powerful but highly toxic last line of defense in treating life-threatening fungal infections in humans with minimal development of microbial resistance. Understanding how this small molecule kills yeast is thus critical for guiding development of derivatives with an improved therapeutic index and other resistance-refractory antimicrobial agents. In the widely accepted ion channel model for its mechanism of cytocidal action, amphotericin forms aggregates inside lipid bilayers that permeabilize and kill cells. In contrast, we report that amphotericin exists primarily in the form of large, extramembranous aggregates that kill yeast by extracting ergosterol from lipid bilayers. These findings reveal that extraction of a polyfunctional lipid underlies the resistance-refractory antimicrobial action of amphotericin and suggests a roadmap for separating its cytocidal and membrane-permeabilizing activities. This new mechanistic understanding is also guiding development of what are to our knowledge the first derivatives of amphotericin that kill yeast but not human cells

Approximation algorithms and hardness results for the joint replenishment Problepm with constant demands

19th Annual European Symposium, Saarbrücken, Germany, September 5-9, 2011. ProceedingsIn the Joint Replenishment Problem (JRP), the goal is to coordinate the replenishments of a collection of goods over time so that continuous demands are satisfied with minimum overall ordering and holding costs. We consider the case when demand rates are constant. Our main contribution is the first hardness result for any variant of JRP with constant demands. When replenishments per commodity are required to be periodic and the time horizon is infinite (which corresponds to the so-called general integer model with correction factor), we show that finding an optimal replenishment policy is at least as hard as integer factorization. This result provides the first theoretical evidence that the JRP with constant demands may have no polynomial-time algorithm and that relaxations and heuristics are called for. We then show that a simple modification of an algorithm by Wildeman et al. (1997) for the JRP gives a fully polynomial-time approximation scheme for the general integer model (without correction factor). We also extend their algorithm to the finite horizon case, achieving an approximation guarantee asymptotically equal to √9/8

Exploring the substrate scope of Baeyer-Villiger monooxygenases with branched lactones as entry towards polyesters

Baeyer-Villiger monooxygenases (BVMOs) are biocatalysts able to convert cyclic ketones to lactones by the insertion of oxygen. The aim of this study was to explore the substrate scope of several BVMOs with (biobased) cyclic ketones as precursors for the synthesis of branched polyesters.The product structure and the degree of conversion of several biotransformations was determined after conversions using self-sufficient BVMOs. Full regioselectivity towards the normal lactone of jasmatone and menthone was observed, while the oxidation of other substrates such as α,β-thujone and 3,3,5-trimethylcyclohexanone resulted in mixtures of regio-isomers. This exploration of the substrate scope of both established as well as newly discovered BVMOs towards biobased ketones contributes to the development of branched polyesters from renewable resources

Salvage photodynamic therapy for recurrent nasopharyngeal carcinoma

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A Prospective Life Cycle Assessment (LCA) of Monomer Synthesis: Comparison of Biocatalytic and Oxidative Chemistry

Biotechnological processes are typically perceived to be greener than chemical processes. A life cycle assessment (LCA) was performed to compare the chemical and biochemical synthesis of lactones obtained by Baeyer-Villiger oxidation. The LCA is prospective (based on experiments at a small scale with primary data) because the process is at an early stage. The results show that the synthesis route has no significant effect on the climate change impact [(1.65 +/- 0.59)kgCO2 g(product)(-1) vs. (1.64 +/- 0.67)kgCO2 g(product)(-1)]. Key process performance metrics affecting the environmental impact were evaluated by performing a sensitivity analysis. Recycling of solvents and enzyme were shown to provide an advantage to the enzymatic synthesis. Additionally, the climate change impact was decreased by 71% if renewable electricity was used. The study shows that comparative LCAs can be used to usefully support decisions at an early stage of process development.</p

Can an online clinical data management service help in improving data collection and data quality in a developing country setting?

Background: Data collection by Electronic Medical Record (EMR) systems have been proven to be helpful in data collection for scientific research and in improving healthcare. For a multi-centre trial in Indonesia and the Netherlands a web based system was selected to enable all participating centres to easily access data. This study assesses whether the introduction of a Clinical Trial Data Management service (CTDMS) composed of electronic Case Report Forms (eCRF) can result in effective data collection and treatment monitoring. Methods: Data items entered were checked for inconsistencies automatically when submitted online. The data were divided into primary and secondary data items. We analysed both the total number of errors and the change in error rate, for both Primary and Secondary items, over the first five month of the trial. Results: In the first five months 51 patients were entered. The Primary data error rate was 1.6%, whilst that for Secondary data was 2.7% against acceptable error rates for analysis of 1% and 2.5% respectively. Conclusion: The presented analysis shows that after five months since the introduction of the CTDMS the Primary and Secondary data error rates reflect acceptable levels of data quality. Furthermore, these error rates were decreasing over time. The digital nature of the CTDMS, as well as the online availability of that data, gives fast and easy insight in adherence to treatment protocols. As such, the CTDMS can serve as a tool to train and educate medical doctors and can improve treatment protocols.Maarten A Wildeman, Jeroen Zandbergen, Andrew Vincent, Camelia Herdini, Jaap M Middeldorp, Renske Fles, Otilia Dalesio, Emile van der Donk, I Bing Ta