A self‐calibrating led‐based solar test platform

A compact platform for testing solar cells is presented. The light source comprises a multi‐wavelength high‐power LED (light emitting diode) array allowing the homogenous illumination of small laboratory solar cell devices (substrate size 50 × 25 mm) within the 390–940 nm wavelength range. The spectrum can be synthesized by independent tuning of the 18 different wavelengths to mimic AM1.5G as well as various indoor lamp spectra. The intensity can be controlled with a 2¹⁴‐bit accuracy and intensities up to 3 suns are possible with an approximate AM1.5G spectral distribution. For several wavelengths intensities up to 10 suns is possible, and for a few wavelengths up to 30 suns can be reached. The setup is equipped with reference diodes and an optical fibre coupling enabling calibration, monitoring and control of the light impinging on the sample. Through a computer controlled interface, it is possible to perform all the commonly employed measurements on the solar cell at very high speed without moving the sample. In particular, the LED‐based illumination system provides an alternative to light‐biased incident photon‐to‐current efficiency measurement to be performed which we demonstrate. Both top and bottom contact is possible and the atmosphere can be controlled around the sample during measurements. The setup was developed for the field of polymer and organic solar cells with particular emphasis on enabling different laboratories to perform measurements in the same manner and obtain a common basis for comparing data. The use of the platform is demonstrated using a standard P3HT:PCBM polymer solar cell but is generally applicable to any solar cell technology with a spectral response in the 390–950 nm region. Copyright © 2010 John Wiley & Sons, Ltd.     

An acrylate-based quasi-solid polymer electrolyte incorporating a novel dinitrile poly(ethylene glycol) plasticizer for lithium-ion batteries

Journal of Materials Science - The performance of solid polymer electrolytes is characterized by lower ionic conductivity than conventional liquid electrolytes but provides advantages in terms of...     

New Insights to Clathrin and Adaptor Protein 2 for the Design and Development of Therapeutic Strategies

The Amyloid Precursor Protein (APP) has been extensively studied for its role as the precursor of the β-amyloid protein (Aβ) in Alzheimer’s disease (AD). However, our understanding of the normal function of APP is still patchy. Emerging evidence indicates that a dysfunction in APP trafficking and degradation can be responsible for neuronal deficits and progressive degeneration in humans. We recently reported that the Y₆₈₂ mutation in the ₆₈₂YENPTY₆₈₇ domain of APP affects its binding to specific adaptor proteins and leads to its anomalous trafficking, to defects in the autophagy machinery and to neuronal degeneration. In order to identify adaptors that influence APP function, we performed pull-down experiments followed by quantitative mass spectrometry (MS) on hippocampal tissue extracts of three month-old mice incubated with either the ₆₈₂YENPTY₆₈₇ peptide, its mutated form, ₆₈₂GENPTY₆₈₇ or its phosphorylated form, ₆₈₂pYENPTY₆₈₇. Our experiments resulted in the identification of two proteins involved in APP internalization and trafficking: Clathrin heavy chain (hc) and its Adaptor Protein 2 (AP-2). Overall our results consolidate and refine the importance of Y₆₈₂ in APP normal functions from an animal model of premature aging and dementia. Additionally, they open the perspective to consider Clathrin hc and AP-2 as potential targets for the design and development of new therapeutic strategies.     

Size-Dependent Cellular Uptake of RGD Peptides

Monomeric RGD peptides show unspecific fluid-phase uptake in cells, whereas multimeric RGD peptides are thought to be internalized by integrin-mediated endocytosis. However, a potential correlation between uptake mechanism and molecular mass has been neglected so far. A dual derivatization of peptide c(RGDw(7Br)K) was performed to investigate this. A fluorescent probe was installed by chemoselective Suzuki–Miyaura cross-coupling of the 7-bromotryptophan and a poly(ethylene glycol) (PEG) linker was attached to the lysine residue. Flow cytometry and live cell imaging confirmed unspecific uptake of the small, non-PEGylated peptide, whereas the PEG₅₀₀₀ peptide conjugate unveiled a selective internalization by M21 cells overexpressing α_vβ₃ and no uptake in α_v-deficient M21L cells.     

A framework for understanding institutional factors affecting the success and failure of offshoring models in India

The objective of this paper is to identify and analyse the factors that influence offshore location decisions from an institutional theory perspective. In the years, emerging economies have shown great growth potential and have attracted significant foreign direct investment, especially from companies willing to set up operations. Despite such a seemingly favourable trade environment, not all companies that entered an emerging economy have been successful. Thus, there is a need to understand the factors that influence the success of any offshore location decision. It is also important to understand the relative importance of these factors, in order to develop novel insights useful to practitioners. There is a lack of literature addressing this issue, which this study aims to fill. We conducted a multi-case analysis with examples of European companies entering India. The findings indicate that successful companies employed locally focused business strategies that enabled them to acquire important relationships and knowledge, and also to adapt to formal institutions, including governmental and regulatory procedures. It was found that, irrespective of size, disregarding collaborative strategies was the main reason for exiting India. These findings are highly relevant for managers and policy makers.     

EGFR-Binding Peptides: From Computational Design towards Tumor-Targeting of Adeno-Associated Virus Capsids

The epidermal growth factor receptor (EGFR) plays a central role in the progression of many solid tumors. We used this validated target to analyze the de novo design of EGFR-binding peptides and their application for the delivery of complex payloads via rational design of a viral vector. Peptides were computationally designed to interact with the EGFR dimerization interface. Two new peptides and a reference (EDA peptide) were chemically synthesized, and their binding ability characterized. Presentation of these peptides in each of the 60 capsid proteins of recombinant adeno-associated viruses (rAAV) via a genetic based loop insertion enabled targeting of EGFR overexpressing tumor cell lines. Furthermore, tissue distribution and tumor xenograft specificity were analyzed with systemic injection in chicken egg chorioallantoic membrane (CAM) assays. Complex correlations between the targeting of the synthetic peptides and the viral vectors to cells and in ovo were observed. Overall, these data demonstrate the potential of computational design in combination with rational capsid modification for viral vector targeting opening new avenues for viral vector delivery and specifically suicide gene therapy.     

Flocculation of activated sludge flocs by stimulation of the aerobic biological activity

Activated sludge flocs are known to deflocculate under short-term anaerobic conditions, but little is known about possible reflocculation under subsequent aerobic conditions. When activated sludge flocs from two wastewater treatment plants deflocculated under anaerobic conditions with well-defined shear conditions, they could be almost, but not completely, reflocculated by aeration for 1-2 h under the same shear conditions. If the biological activity was reduced by adding azide, chloramphenicol or by decreasing the temperature, no or only very little reflocculation took place. This indicated that the reflocculation was under direct or indirect microbial control. Only a small part of the reflocculation was due to improved flocculation properties obtained by oxidation of Fe(II) to Fe(III), which is a better flocculant. Fe(II) was produced under the anaerobic conditions by microbial iron reduction, and it was oxidized to Fe(III) within less than one hour after the aeration was started. However, by comparing two different sludges with different capabilities for iron reduction, iron oxidation and responses to substrate addition, it was found that the aerobic biological activity most likely was of greatest significance for the observed reflocculation and floc formation under aerobic conditions. This was further supported by adding organic substrates (glucose or ethanol) during the aerobic reflocculation phase, which promoted reflocculation. However, some substrates had the opposite effect (acetate and lactate), where a deterioration of the reflocculation was observed, probably due to different responses from different groups of microorganisms in the sludges.     

Central venous oxygen saturation and thoracic admittance during dialysis: new approaches to hemodynamic monitoring

Intradialytic hypotension (IDH) is one of the most important short-term complications to hemodialysis (HD). Inadequate cardiac filling due to a reduction in the central blood volume is believed to be a major etiological factor. The aim of this study was to evaluate whether these pathophysiologic events are reflected in the central venous oxygen saturation (ScO(2)) and thoracic admittance (TA) during dialysis. Twenty ambulatory HD patients, 11 hypotension prone (HP) and 9 hypotension resistant, with central vascular access, were monitored during 3 HD sessions each. ScO(2), TA, finger blood pressure (BP), and relative change in blood volume (DeltaBV) were measured and sampled continuously. The relative TA decrease and DeltaBV were both largest in the HP group (p<0.05 for both), whereas ScO(2) decreased only in HP patients (p<0.001). Baseline TA was lower in the HP group (p<0.01). Changes in ScO(2) and TA correlated much closer than did changes in ScO(2) and DeltaBV (r=0.43 and 0.18, respectively). Our results suggest that an intradialytic decrease in cardiac output, as reflected by a fall in ScO(2), is a common feature to HD patients prone to IDH. In patients using a central vascular access, ScO(2) and TA measurements may be more specific to the pathophysiologic events preceding IDH than DeltaBV-the current standard monitoring method.     

A chromatographic approach for fluorescence reduction in liquid Raman analysis

In this study a chromatographic approach for fluorescence reduction in liquid Raman analysis has been evaluated. The idea behind the approach is to apply a chromatographic separation step prior to Raman analysis in order to separate fluorescing compounds from other components of interest, thus facilitating better quantitative and qualitative analysis of the latter components. A real-time liquid-core Raman waveguide detector designed for chromatographic applications was used in the study, thus providing real-time chemical pretreatment of liquid samples for Raman analysis. Twenty aqueous mixtures of additives frequently found in beverages were analyzed, and for comparative purposes the mixtures were also analyzed in the Raman waveguide detector without chromatographic separation and with a conventional immersion probe. Both qualitatively and quantitatively satisfying results were obtained using the chromatographic Raman approach, and the technique provided possibilities for quantitative and qualitative assessments superior to the two other instrumental setups. The technique may provide additional benefits through sensitivity enhancements, and the approach is simple, inexpensive, and easy to implement in the average applied Raman laboratory. The analysis of various chemical systems and factors such as system stability over time need further evaluation in order to confirm the general applicability of the approach.