Effect of Fiber Length on Carbon Nanotube-Induced Fibrogenesis

Given their extremely small size and light weight, carbon nanotubes (CNTs) can be readily inhaled by human lungs resulting in increased rates of pulmonary disorders, particularly fibrosis. Although the fibrogenic potential of CNTs is well established, there is a lack of consensus regarding the contribution of physicochemical attributes of CNTs on the underlying fibrotic outcome. We designed an experimentally validated in vitro fibroblast culture model aimed at investigating the effect of fiber length on single-walled CNT (SWCNT)-induced pulmonary fibrosis. The fibrogenic response to short and long SWCNTs was assessed via oxidative stress generation, collagen expression and transforming growth factor-beta (TGF-β) production as potential fibrosis biomarkers. Long SWCNTs were significantly more potent than short SWCNTs in terms of reactive oxygen species (ROS) response, collagen production and TGF-β release. Furthermore, our finding on the length-dependent in vitro fibrogenic response was validated by the in vivo lung fibrosis outcome, thus supporting the predictive value of the in vitro model. Our results also demonstrated the key role of ROS in SWCNT-induced collagen expression and TGF-β activation, indicating the potential mechanisms of length-dependent SWCNT-induced fibrosis. Together, our study provides new evidence for the role of fiber length in SWCNT-induced lung fibrosis and offers a rapid cell-based assay for fibrogenicity testing of nanomaterials with the ability to predict pulmonary fibrogenic response in vivo.     

Phenology of the landscape: the role of organic agriculture

It is becoming increasingly clear that the agricultural sector will have to find an additional raison d'être beyond the production of food alone. One of the new services that agriculture can provide is contributing to the environmental quality of rural areas. In this respect a great burden of expectation is placed on organic farming. Here we examine how organic farming can contribute to the quality of specific regional landscapes. We do this with the help of a new instrument, the phenology of the landscape, which measures the contributions made by organic and conventional farming to the succession of colours and shapes during the seasons. This seasonal development plays an important role in people's appreciation of the landscape. The study shows that seasonal development is more recognizable on organic farms than on conventional farms, and that seasonal development is a scientifically‐usable criterion for evaluating the environmental quality of farms.     

Spatial and temporal sequence of events in cell adhesion: from molecular recognition to focal adhesion assembly

A new concept that attributes a pivotal role to the pericellular coat in the regulation of the early stages of cell adhesion is presented. Quick, adaptable, and transient adhesion through multiple cooperative weak interactions provides the cell with an additional level of modulation in the decision-making process that precedes the commitment to adhesion at a particular site. Hyaluronan emerges as a modulator of cell adhesion in certain cells, mediating binding or repulsion through its polyelectrolyte character, in addition to its chirality and molecular-recognition properties. The biophysical properties of hyaluronan as well as its ultrastructural organization are analyzed in relation to this proposed function.     

On the appreciation of visual diversity in housing environments

Journal of Housing and the Built Environment -     

Conditions and costs for renewables electricity grid connection: Examples in Europe

This paper compares conditions and costs for RES-E grid connection in selected European countries. These are Germany, the Netherlands, the United Kingdom, Sweden, Austria, Lithuania and Slovenia. Country specific case studies are presented for wind onshore and offshore, biomass and photovoltaic power systems, as based on literature reviews and stakeholder interviews. It is shown that, especially for wind offshore, the allocation of grid connection costs can form a significant barrier for the installation of new RES-E generation if the developer has to bear all such costs. If energy policy makers want to reduce the barriers for new large-scale RES-E deployment, then it is concluded that the grid connection costs should be covered by the respective grid operator. These costs may then be recouped by increasing consumer tariffs for the use of the grid.     

Compressed Air Energy Storage in an Electricity System With Significant Wind Power Generation

In this paper, a stochastic electricity market model is applied to estimate the effects of significant wind power generation on system operation and on economic value of investments in compressed air energy storage (CAES). The model's principle is cost minimization by determining the system costs mainly as a function of available generation and transmission capacities, primary energy prices, plant characteristics, and electricity demand. To obtain appropriate estimates, notably reduced efficiencies at part load, start-up costs, and reserve power requirements are taken into account. The latter are endogenously modeled by applying a probabilistic method. The intermittency of wind is covered by a stochastic recombining tree and the system is considered to adapt on increasing wind integration over time by endogenous modeling of investments in selected thermal power plants and CAES. Results for a German case study indicate that CAES can be economic in the case of large-scale wind power deployment     

Structural Basis for Metastability in Amorphous Calcium Barium Carbonate (ACBC)

Metastable amorphous precursors are emerging as valuable intermediates for the synthesis of materials with compositions and structures far from equilibrium. Recently, it was found that amorphous calcium barium carbonate (ACBC) can be converted into highly barium‐substituted “balcite,” a metastable high temperature modification of calcite with exceptional hardness. A systematic analysis ACBC (Ca_1‐xBa_xCO₃·1.2H₂O) in the range from x = 0–0.5 is presented. Combining techniques that independently probe the local environment from the perspective of calcium, barium, and carbonate ions, with total X‐ray scattering and a new molecular dynamics/density functional theory simulations approach, provides a holistic picture of ACBC structure as a function of composition. With increasing barium content, ACBC becomes more ordered at short and medium range, and increasingly similar to crystalline balcite, without developing long‐range order. This is not accompanied by a change in the water content and does not carry a significant energy penalty, but is associated with differences in cation coordination resulting from changing carbonate anion orientation. Therefore, the local order imprinted in ACBC may increasingly lower the kinetic barrier to subsequent transformations as it becomes more pronounced. This pathway offers clues to the design of metastable materials by tuning coordination numbers in the amorphous solid state.     

Distribution of costs induced by the integration of RES-E power

This article focuses on the distribution of costs induced by the integration of electricity generation from renewable energy sources (RES-E). The treatment to distribute these costs on different market actors is crucial for its development. For this purpose, individual actors of electricity markets and several cost categories are identified. According to the defined cost structure, possible treatments to distribute the individual cost categories on different relevant actors are described. Finally, an evaluation of the cost distribution treatments based on an economic analysis is given. Economic efficiency recommends that clearly attributable (shallow) grid connection as well as (deep) grid costs are charged to the corresponding RES-E producer and that the RES-E producers are also charged the regulating power costs. However, deep grid integration costs should be updated to reflect evolving scarcities. Also regulating power costs should reflect actual scarcity and thus be symmetric and based on real-time prices, taking into account the overall system imbalance. Moreover, the time span between the closure of the spot market and actual delivery should be chosen as short as possible to enable accurate RES-E production forecasts.     

Parallel decomposition of unstructured FEM-meshes

We present a parallel algorithm for static and dynamic partitioning of unstructured FEM-meshes. The method consists of two parts. First a fast but inaccurate sequential clustering is determined which is used, together with a simple mapping heuristic, to map the mesh initially onto the processors of a parallel system. The second part of the method uses a massively parallel algorithm to remap and optimize the mesh decomposition, taking several cost functions into account which reflect the characteristics of the underlying hardware and the requirements of the numerical solution method supposed to run after the decomposition. The parallel algorithm first calculates the number of nodes that have to be migrated between pairs of clusters in order to obtain an optimal load balancing. In a second step, nodes to be migrated are chosen according to cost functions optimizing the amount of necessary communication and the shapes of subdomains. The latter criterion is extremely important for the convergence behavior of certain numerical solution methods, especially for preconditioned conjugate gradient methods. The parallel parts of the method are implemented in C under Parix to run on the Parsytec GC systems. Results on up to 64 processors are presented and compared to those of other existing methods. © 1998 John Wiley & Sons, Ltd.