Showing papers by "Fraunhofer Society published in 2015"

Solar Cell Efficiency Tables (Version 45)

Abstract: Consolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells and modules are presented. Guidelines for inclusion of results into these tables are outlined and new entries since July 2014 are reviewed. URI: http://onlinelibrary.wiley.com/doi/10.1002/pip.2573/pdf [1] Authors: GREEN Martin A. EMERY Keith HISHIKAWA Y. WARTA W. DUNLOP Ewan Publication Year: 2015 Type: Articles in Journals

IBS: an illustrator for the presentation and visualization of biological sequences.

Abstract: Summary: Biological sequence diagrams are fundamental for visualizing various functional elements in protein or nucleotide sequences that enable a summarization and presentation of existing information as well as means of intuitive new discoveries. Here, we present a software package called illustrator of biological sequences (IBS) that can be used for representing the organization of either protein or nucleotide sequences in a convenient, efficient and precise manner. Multiple options are provided in IBS, and biological sequences can be manipulated, recolored or rescaled in a user-defined mode. Also, the final representational artwork can be directly exported into a publication-quality figure. Availability and implementation: The standalone package of IBS was implemented in JAVA, while the online service was implemented in HTML5 and JavaScript. Both the standalone package and online service are freely available at http://ibs.biocuckoo.org. Contact: renjian.sysu@gmail.com or xueyu@hust.edu.cn Supplementary information: Supplementary data are available at Bioinformatics online.

A four-organ-chip for interconnected long-term co-culture of human intestine, liver, skin and kidney equivalents

Abstract: Systemic absorption and metabolism of drugs in the small intestine, metabolism by the liver as well as excretion by the kidney are key determinants of efficacy and safety for therapeutic candidates. However, these systemic responses of applied substances lack in most in vitro assays. In this study, a microphysiological system maintaining the functionality of four organs over 28 days in co-culture has been established at a minute but standardized microsystem scale. Preformed human intestine and skin models have been integrated into the four-organ-chip on standard cell culture inserts at a size 100 000-fold smaller than their human counterpart organs. A 3D-based spheroid, equivalent to ten liver lobules, mimics liver function. Finally, a barrier segregating the media flow through the organs from fluids excreted by the kidney has been generated by a polymeric membrane covered by a monolayer of human proximal tubule epithelial cells. A peristaltic on-chip micropump ensures pulsatile media flow interconnecting the four tissue culture compartments through microfluidic channels. A second microfluidic circuit ensures drainage of the fluid excreted through the kidney epithelial cell layer. This four-organ-chip system assures near to physiological fluid-to-tissue ratios. In-depth metabolic and gene analysis revealed the establishment of reproducible homeostasis among the co-cultures within two to four days, sustainable over at least 28 days independent of the individual human cell line or tissue donor background used for each organ equivalent. Lastly, 3D imaging two-photon microscopy visualised details of spatiotemporal segregation of the two microfluidic flows by proximal tubule epithelia. To our knowledge, this study is the first approach to establish a system for in vitro microfluidic ADME profiling and repeated dose systemic toxicity testing of drug candidates over 28 days.

Lithium–Sulfur Cells: The Gap between the State‐of‐the‐Art and the Requirements for High Energy Battery Cells

Abstract: Li–S cells are considered a highly attractive electrochemical storage system, especially due to their high potential gravimetric energy density. The long-term target of all Li–S research activities must be to outperform state-of-the-art Li-ion cells. A current benchmark is the Panasonic NCR18650B, which has a gravimetric energy density of ≈240 Wh kg−1 and several hundred relatively stable cycles. The possible 18650 Li–S cell energies and cell costs are calculated for various sulfur loads, sulfur utilizations, and electrolyte/sulfur ratios with the aim of determining the cell and electrode property values required to outperform the NCR18650B. These values are compared with statistical information obtained from an extensive literature review of 274 Li–S publications over the last 12 years to show the gap between state-of-the-art Li–S research and requirements for high energy density cells. Finally, a carbon nanotubes-based electrode is introduced, which meets important criteria for obtaining high gravimetric cell energy densities.

The Chemistry of Redox-Flow Batteries.

Abstract: The development of various redox-flow batteries for the storage of fluctuating renewable energy has intensified in recent years because of their peculiar ability to be scaled separately in terms of energy and power, and therefore potentially to reduce the costs of energy storage. This has resulted in a considerable increase in the number of publications on redox-flow batteries. This was a motivation to present a comprehensive and critical overview of the features of this type of batteries, focusing mainly on the chemistry of electrolytes and introducing a thorough systematic classification to reveal their potential for future development.

Direct Growth of Freestanding ZnO Tetrapod Networks for Multifunctional Applications in Photocatalysis, UV Photodetection, and Gas Sensing

Abstract: Growth of freestanding nano- and microstructures with complex morphologies is a highly desired aspect for real applications of nanoscale materials in various technologies. Zinc oxide tetrapods (ZnO-T), which exhibit three-dimensional (3D) shapes, are of major importance from a technological applications point of view, and thus efficient techniques for growth of different varieties of tetrapod-based networks are demanded. Here, we demonstrate the versatile and single-step synthesis of ZnO-T with different arm morphologies by a simple flame transport synthesis (FTS) approach, forming a network. Morphological evolutions and structural intactness of these tetrapods have been investigated in detail by scanning electron microscopy, X-ray diffraction, and micro-Raman measurements. For a deeper understanding of the crystallinity, detailed high-resolution transmission electron microscopic studies on a typical ZnO tetrapod structure are presented. The involved growth mechanism for ZnO tetrapods with various arm mor...

Hyperbolic phonon-polaritons in boron nitride for near-field optical imaging and focusing

Abstract: Hyperbolic materials exhibit sub-diffractional, highly directional, volume-confined polariton modes. Here we report that hyperbolic phonon polaritons allow for a flat slab of hexagonal boron nitride to enable exciting near-field optical applications, including unusual imaging phenomenon (such as an enlarged reconstruction of investigated objects) and sub-diffractional focusing. Both the enlarged imaging and the super-resolution focusing are explained based on the volume-confined, wavelength dependent propagation angle of hyperbolic phonon polaritons. With advanced infrared nanoimaging techniques and state-of-art mid-infrared laser sources, we have succeeded in demonstrating and visualizing these unexpected phenomena in both Type I and Type II hyperbolic conditions, with both occurring naturally within hexagonal boron nitride. These efforts have provided a full and intuitive physical picture for the understanding of the role of hyperbolic phonon polaritons in near-field optical imaging, guiding, and focusing applications.

Clinical and inflammatory characteristics of the European U-BIOPRED adult severe asthma cohort

Abstract: U-BIOPRED is a European Union consortium of 20 academic institutions, 11 pharmaceutical companies and six patient organisations with the objective of improving the understanding of asthma disease mechanisms using a systems biology approach.This cross-sectional assessment of adults with severe asthma, mild/moderate asthma and healthy controls from 11 European countries consisted of analyses of patient-reported outcomes, lung function, blood and airway inflammatory measurements.Patients with severe asthma (nonsmokers, n=311; smokers/ex-smokers, n=110) had more symptoms and exacerbations compared to patients with mild/moderate disease (n=88) (2.5 exacerbations versus 0.4 in the preceding 12 months; p<0.001), with worse quality of life, and higher levels of anxiety and depression. They also had a higher incidence of nasal polyps and gastro-oesophageal reflux with lower lung function. Sputum eosinophil count was higher in severe asthma compared to mild/moderate asthma (median count 2.99% versus 1.05%; p=0.004) despite treatment with higher doses of inhaled and/or oral corticosteroids.Consistent with other severe asthma cohorts, U-BIOPRED is characterised by poor symptom control, increased comorbidity and airway inflammation, despite high levels of treatment. It is well suited to identify asthma phenotypes using the array of "omic" datasets that are at the core of this systems medicine approach.

Innovations in nanotechnology for water treatment.

Abstract: Important challenges in the global water situation, mainly resulting from worldwide population growth and climate change, require novel innovative water technologies in order to ensure a supply of drinking water and reduce global water pollution. Against this background, the adaptation of highly advanced nanotechnology to traditional process engineering offers new opportunities in technological developments for advanced water and wastewater technology processes. Here, an overview of recent advances in nanotechnologies for water and wastewater treatment processes is provided, including nanobased materials, such as nanoadsorbents, nanometals, nanomembranes, and photocatalysts. The beneficial properties of these materials as well as technical barriers when compared with conventional processes are reported. The state of commercialization is presented and an outlook on further research opportunities is given for each type of nanobased material and process. In addition to the promising technological enhancements, the limitations of nanotechnology for water applications, such as laws and regulations as well as potential health risks, are summarized. The legal framework according to nanoengineered materials and processes that are used for water and wastewater treatment is considered for European countries and for the USA.

Upconversion for Photovoltaics – A Review of Materials, Devices and Concepts for Performance Enhancement

Abstract: Upconversion of low-energy photons into high-energy photons increases the efficiency of photovoltaic devices by converting photons with energies below the absorption threshold of the solar cell into photons that can be utilized. In this review, an overview is provided of quantitative studies of the upconversion quantum yield of upconverter materials, and of the achieved efficiency enhancements in upconverting solar cell devices. Different materials and devices are compared based on well-defined figures-of-merit and the challenges to their accurate measurement are discussed. Internal upconversion quantum yields above 13% have been reported both for Er3+-based materials as well as for organic upconverters, using irradiance values below 0.4 W cm−2. On the upconverting solar cell device level, relative enhancements of the solar cells' short-circuit currents by up to 0.55% have been achieved. These values document progress by orders of magnitude achieved in the last years. However, they also show that the field of upconversion needs further development to become a relevant technology option in photovoltaics. Different options regarding how upconversion performance can be increased further in the future are outlined.

Perfluoroalkyl and polyfluoroalkyl substances in consumer products

Abstract: Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are used in a wide range of products of all day life. Due to their toxicological potential, an emerging focus is directed towards their exposure to humans. This study investigated the PFAS load of consumer products in a broad perspective. Perfluoroalkyl sulfonic acids (C4, C6-C8, C10-PFSA), carboxylic acids (C4-C14-PFCA) and fluorotelomer alcohols (4:2, 6:2; 8:2 and 10:2 FTOH) were analysed in 115 random samples of consumer products including textiles (outdoor materials), carpets, cleaning and impregnating agents, leather samples, baking and sandwich papers, paper baking forms and ski waxes. PFCA and PFSA were analysed by HPLC-MS/MS, whereas FTOH were detected by GC/CI-MS. Consumer products such as cleaning agents or some baking and sandwich papers show low or negligible PFSA and PFCA contents. On the other hand, high PFAS levels were identified in ski waxes (up to about 2000 μg/kg PFOA), leather samples (up to about 200 μg/kg PFBA and 120 μg/kg PFBS), outdoor textiles (up to 19 μg/m(2) PFOA) and some other baking papers (up to 15 μg/m(2) PFOA). Moreover, some test samples like carpet and leather samples and outdoor materials exceeded the EU regulatory threshold value for PFOS (1 μg/m(2)). A diverse mixture of PFASs can be found in consumer products for all fields of daily use in varying concentrations. This study proves the importance of screening and monitoring of consumer products for PFAS loads and the necessity for an action to regulate the use of PFASs, especially PFOA, in consumer products.

The performance impact of supply chain agility and supply chain adaptability: the moderation effect of product complexity

Abstract: Even though research has suggested that supply chain agility and supply chain adaptability are distinct capabilities, little is known about their performance effects and about the contextual conditions under which they are effective. Based on a sample of 143 German firms, we empirically investigate the effects of supply chain agility and supply chain adaptability on cost performance and operational performance using hierarchical regression analysis. We ground our investigation in the dynamic capabilities view and contingency theory. We find that supply chain agility and supply chain adaptability positively affect both cost performance and operational performance. We further find evidence for a mediating role of supply chain agility in the links between supply chain adaptability and performance. Product complexity positively moderates the links between supply chain adaptability and cost performance, and supply chain adaptability and operational performance. The results contribute to the literature by offer...

Charge Carrier Separation in Solar Cells

Abstract: The selective transport of electrons and holes to the two terminals of a solar cell is often attributed to an electric field, although well-known physics states that they are driven by gradients of quasi-Fermi energies. However, in an illuminated semiconductor, these forces are not selective, and they drive both charge carriers toward both contacts. This paper shows that the necessary selectivity is achieved by differences in the conductivities of electrons and holes in two distinct regions of the device, which, for one charge carrier, allows transport to one contact and block transport to the other contact.

ZnO Hard Templating for Synthesis of Hierarchical Porous Carbons with Tailored Porosity and High Performance in Lithium-Sulfur Battery

Abstract: © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 287 wileyonlinelibrary.com However, despite more than two decades of intensive scientifi c research focusing on all cell components, the wide market penetration of a viable Li-S battery has not been realized so far. This is caused by several challenges coupled with the complicated electrochemical conversion of sulfur in liquid organic electrolytes. Major drawbacks are the repeated dissolution and deposition of highly insulating sulfur compounds and the extensive expansion and shrinking of the active material (mechanical degradation of the cathode structure) during cycling. [ 4–6 ] Moreover, the Coulombic effi ciency of the Li-S cell is largely decreased by a parasitic selfdischarge mechanism referred to as polysulfi de shuttle. [ 7 ]

Nonlinear aging characteristics of lithium-ion cells under different operational conditions

Abstract: The potential reuse of lithium-ion batteries exhausted upon electric vehicle operation is a broadly discussed topic. However, a profound understanding of battery aging behavior is a prerequisite to assess overall system cost and economic benefit of battery reuse: Whereas the capacity fade under load is commonly reported to show a linear dependency on charge throughput, a turning point to nonlinear aging characteristics is observed at residual capacities of about 80% under different operational conditions. Based on a widespread aging matrix, results indicate an earlier appearance of nonlinear characteristics at high charging rates and operational voltage windows but low temperatures. Scanning electron microscopy images reveal areas of thick surface films at the anode while the cathode stays unmodified. Therefore, a thickening of the solid electrolyte interphase, catalyzed by oxidation products migrating to the anode, is believed to be the dominating aging mechanism before the turning point. Afterwards, lithium plating might even occur at moderate temperatures and charging rates due to deteriorated ionic kinetics and graphite active material loss. As all these mechanisms are dependent on the cell potential, an optimized operational strategy may avoid or retard nonlinear aging characteristics and extend the life of lithium-ion cells.

Efficient direct solar-to-hydrogen conversion by in situ interface transformation of a tandem structure

Abstract: Photosynthesis is nature’s route to convert intermittent solar irradiation into storable energy, while its use for an industrial energy supply is impaired by low efficiency. Artificial photosynthesis provides a promising alternative for efficient robust carbon-neutral renewable energy generation. The approach of direct hydrogen generation by photoelectrochemical water splitting utilizes customized tandem absorber structures to mimic the Z-scheme of natural photosynthesis. Here a combined chemical surface transformation of a tandem structure and catalyst deposition at ambient temperature yields photocurrents approaching the theoretical limit of the absorber and results in a solar-to-hydrogen efficiency of 14%. The potentiostatically assisted photoelectrode efficiency is 17%. Present benchmarks for integrated systems are clearly exceeded. Details of the in situ interface transformation, the electronic improvement and chemical passivation are presented. The surface functionalization procedure is widely applicable and can be precisely controlled, allowing further developments of high-efficiency robust hydrogen generators.

Impact of charge transport on current–voltage characteristics and power-conversion efficiency of organic solar cells

Abstract: This work elucidates the impact of charge transport on the photovoltaic properties of organic solar cells. Here we show that the analysis of current-voltage curves of organic solar cells under illumination with the Shockley equation results in values for ideality factor, photocurrent and parallel resistance, which lack physical meaning. Drift-diffusion simulations for a wide range of charge-carrier mobilities and illumination intensities reveal significant carrier accumulation caused by poor transport properties, which is not included in the Shockley equation. As a consequence, the separation of the quasi Fermi levels in the organic photoactive layer (internal voltage) differs substantially from the external voltage for almost all conditions. We present a new analytical model, which considers carrier transport explicitly. The model shows excellent agreement with full drift-diffusion simulations over a wide range of mobilities and illumination intensities, making it suitable for realistic efficiency predictions for organic solar cells.

Digitalized Product-Service Systems in Manufacturing Firms: A Case Study Analysis

Abstract: The merging trends of digitalization and servitization harbor extensive and largely unexplored potential for manufacturing firms. Digital systems can be linked with product-service bundles to build...

The real type and ideal type of transdisciplinary processes: part I—theoretical foundations

Abstract: Transdisciplinarity integrates or relates different epistemics from science and practice (Mode 2 transdisciplinarity) or from branches of disciplines if interdisciplinary integration is impossible (Mode 1 transdisciplinarity). The paper explains, based on an analysis of the historical development of the Mode 2 transdisciplinarity concept, how transdisciplinary processes link interdisciplinary applied research and multi-stakeholder discourses by facilitating methods. We elaborate on what type of problems may be managed using what knowledge, how this might be accomplished, what types of objectives are desired, and by what organizational means. Thus the paper presents ontology, epistemology, methodology, functionality, and organization of an ideal type of transdisciplinary process. Socially robust orientations are the expected outcomes of this process. These orientations provide science-based, state-of-the-art, socially accepted options of solutions which acknowledge uncertainties and the incompleteness of different forms of epistemics (i.e., of knowing or thought), in particular within the sustainable transitioning of complex real-world problems.

Cell death stages in single apoptotic and necrotic cells monitored by Raman microspectroscopy

Abstract: Although apoptosis and necrosis have distinct features, the identification and discrimination of apoptotic and necrotic cell death in vitro is challenging. Immunocytological and biochemical assays represent the current gold standard for monitoring cell death pathways; however, these standard assays are invasive, render large numbers of cells and impede continuous monitoring experiments. In this study, both room temperature (RT)-induced apoptosis and heat-triggered necrosis were analyzed in individual Saos-2 and SW-1353 cells by utilizing Raman microspectroscopy. A targeted analysis of defined cell death modalities, including early and late apoptosis as well as necrosis, was facilitated based on the combination of Raman spectroscopy with fluorescence microscopy. Spectral shifts were identified in the two cell lines that reflect biochemical changes specific for either RT-induced apoptosis or heat-mediated necrosis. A supervised classification model specified apoptotic and necrotic cell death based on single cell Raman spectra. To conclude, Raman spectroscopy allows a non-invasive, continuous monitoring of cell death, which may help shedding new light on complex pathophysiological or drug-induced cell death processes.

Stability assessment of alternative platinum free counter electrodes for dye-sensitized solar cells

Abstract: Platinum (Pt)-free counter electrodes (CEs) are economical alternative components of dye-sensitized solar cells (DSSCs) that have attracted much interest and become the focus of research, with an increasingly large number of scientific papers published in the last two decades. The development of these CE materials was driven mainly by desires to overcome the disadvantages of Pt, as follows: high cost, scarcity, corrosion by the I3−/I− redox couple electrolyte, and mismatch or non-effectivity in the I-free redox couple electrolyte. Although much more is now known about the principal physicochemical processes that occur during CE operation of the DSSC, the stability issues associated with CEs have not been matched by the exponential increase in CE research effort. This raises questions regarding the stability of the CEs whether the present research is sufficiently addressing the stability issues that limit DSSC performance. This review attempts to identify some of the key techniques that evaluate CE stability in DSSCs through a selective presentation of recent research highlights. Classical approaches could effectively assess the probability of using alternative Pt-free CE materials for commercial application, which offer strategies to overcome the current stability stalemate.

Additive Manufacturing Technologies Compared: Morphology of Deposits of Silver Ink Using Inkjet and Aerosol Jet Printing

Abstract: We report about a detailed comparison of the additive manufacturing methods inkjet printing (IJP) and aerosol jet printing (AJP). Both technologies are based on the direct-writing approach enabling the non-contact deposition of various materials in flexible patterns, e.g., for printed electronic applications. The deposited pattern elements were classified as (i) drops (IJP) or splats (AJP), (ii) lines, and (iii) squares. These elements can be considered as basic elements of the deposition systems and also of printed electronics. The pattern elements were deposited with IJP and AJP using the same silver nanoparticle ink. After printing, the layers were characterized regarding their morphology by optical and topographical measurement methods as well as regarding their electrical characteristics. It turned out that drops deposited with IJP and splats deposited with AJP can have similar dimensions. However, the shapes of the deposits differ widely. In the case of lines, AJP enables narrower line widths and th...