Exergy analysis of incremental sheet forming

Research in the last 15 years has led to die-less incremental forming processes that are close to realization in an industrial setup. Whereas many studies have been carried out with the intention of investigating technical abilities and economic consequences, the ecological impact of incremental sheet forming (ISF) has not been studied so far. Using the concept of exergy analysis, two ISF technologies, namely single sided and double sided incremental forming, are investigated and compared to conventional forming and hydroforming. A second exergy analysis is carried out with the purpose of examining the environmental impact of different forming technologies from a supply chain perspective. Therefore, related upstream activities (die set production, aluminum sheet production and energy conversion and supply) are included into the exergy analysis. The entire supply chain is modeled with Matlab/Simulink. The results of both analyses suggest that ISF is environmentally advantageous for prototyping and small production runs.     

Synthesis,characterization and comparative OFET behaviour of indenofluorene–bithiophene and terthiophene alternating copolymers

The synthesis of alternating copolymers of tetraalkylindenofluorene with bithiophene and terthiophene using Suzuki polycondensation route is reported. We report on the optical and electrochemical properties of these copolymers. AFM analysis of the microscopic morphology of thin deposits showed that the copolymer with terthiophene units produced the more ordered films, with well-defined fibrillar structures, resulting from highly-regular dense packing due to strong π–π interchain interactions, in contrast to the amorphous bithiophene copolymer. Upon testing these materials in FETs the terthienyl copolymers displayed the higher charge mobilities among the studied compounds, with values of over 10^?4 cm² V^?1 s^?1 being obtained.     

Crosslinking behavior of dextran modified with hydroxyethyl methacrylate upon irradiation with visible light—Effect of concentration,coinitiator type,and solvent

This study presents the synthesis of a crosslinkable dextran as starting material for the development of new hydrogels as drug delivery system in dental applications. 2‐Hydroxyethyl methacrylate (HEMA) was coupled to dextran after activation with carbonyldiimidazole as monitored by FTIR and ¹H‐NMR spectroscopy. The Dex‐HEMA was crosslinked by visible light in the presence of camphorquinone (CQ) as photoinitiator and a coinitiator in a proper solvent. Aliphatic or aromatic amines were used as coinitiators and the content of the coinitiator was varied from 0.25 to 3.0 mol %. Diphenyliodonium chloride was added as a third component to the above photoinitiation system. It was observed that, the degree of swelling decreased upon an increase of Dex‐HEMA concentration and the water content in the solvent system due to formation of more crosslinking points, that is, increasing crosslink density (P_x). The type of coinitiator shows a prominent impact on the swelling behavior and crosslinking efficiency of hydrogels. Special cryofixation and cryofracture techniques were used to investigate the surface and interior of swollen Dex‐HEMA hydrogel samples by SEM. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effects of cropping history and phosphorus source on yield and nitrogen fixation in sole and intercropped cowpea–maize systems

Symbiotic N₂-fixation, N uptake efficiency, biomass- and crop production of cowpea and maize as affected by P source, sole- and intercropped, and introduction of break crops were studied on a farmer’s fields in semi-arid Tanzania. Cowpea fixed around 60% of its N from the atmosphere amounting to 70 kg N ha⁻¹ under sole and 36 kg N ha⁻¹ under intercropping as estimated by the ¹⁵N isotope dilution method around peak biomass production. The amount of N₂-fixed was 30–40% higher when P was applied as either TSP or MRP whereas cowpea yield were unaffected. Intercropped maize with 19,000 plant ha⁻¹ accumulated the same amount of N as 38,000 sole cropped maize plants although intercropping reduced the dry matter accumulation by 25%. The N uptake efficiency of the applied ¹⁵N labelled fertiliser was 26%, which equal a total pool of early available plant N of 158 kg N ha⁻¹. Under the N deficient conditions, P application did not increase the grain yield of maize. The LER indicate that sole cropping required 18% more area than intercropping in order to produce the same grain yield, and 35% more land when LER was based on N uptakes. Introduction of break crops in the maize systems, more than doubled accumulation of dry matter and N in the grain compared to continuous maize cropping. During maturation sole crop cowpea shedded leaves containing 41 kg N ha⁻¹. The current findings underline the importance of crop diversity in Sub Saharan Africa agriculture and emphasise the need for including all residues, including shedded leaves, in nutrient balance studies.     

Site-specific chemical modification of proteins with a prelabelled cysteine tag using the artificially split Mxe GyrA intein

The selective modification of proteins with a synthetic probe is of central interest for many aspects of protein chemistry. We have recently reported a new approach in which a short cysteine-containing tag (CysTag) fused to one part of a split intein is first modified with a sulfhydryl-reactive probe. In a second step, protein trans-splicing is used to link the labelled CysTag to a target protein that has been expressed in fusion with the complementary split intein fragment. Here, we present the generation and biochemical characterisation of the artificially split Mycobacterium xenopi GyrA intein. We show that this split intein is active without a renaturation step and that it provides a significant improvement for the CysTag protein-labelling approach in terms of product yields and target protein tolerance. Two proteins with multiple cysteine residues, human growth hormone and a multidomain nonribosomal peptide synthetase, were site-specifically modified with high yields. Our approach combines the benefits of the plethora of commercially available cysteine-reactive probes with a straightforward route for their site-specific incorporation even into complex and cysteine-rich proteins.     

Proteins Marking the Sequence of Genotoxic Signaling from Irradiated Mesenchymal Stromal Cells to CD34+ Cells

Non-targeted effects (NTE) of ionizing radiation may initiate myeloid neoplasms (MN). Here, protein mediators (I) in irradiated human mesenchymal stromal cells (MSC) as the NTE source, (II) in MSC conditioned supernatant and (III) in human bone marrow CD34+ cells undergoing genotoxic NTE were investigated. Healthy sublethal irradiated MSC showed significantly increased levels of reactive oxygen species. These cells responded by increasing intracellular abundance of proteins involved in proteasomal degradation, protein translation, cytoskeleton dynamics, nucleocytoplasmic shuttling, and those with antioxidant activity. Among the increased proteins were THY1 and GNA11/14, which are signaling proteins with hitherto unknown functions in the radiation response and NTE. In the corresponding MSC conditioned medium, the three chaperones GRP78, CALR, and PDIA3 were increased. Together with GPI, these were the only four altered proteins, which were associated with the observed genotoxic NTE. Healthy CD34+ cells cultured in MSC conditioned medium suffered from more than a six-fold increase in γH2AX focal staining, indicative for DNA double-strand breaks, as well as numerical and structural chromosomal aberrations within three days. At this stage, five proteins were altered, among them IQGAP1, HMGB1, and PA2G4, which are involved in malign development. In summary, our data provide novel insights into three sequential steps of genotoxic signaling from irradiated MSC to CD34+ cells, implicating that induced NTE might initiate the development of MN.     

Theory and application of Agricultural Innovation Platforms for improved irrigation scheme management in Southern Africa

Abstract

Many small-scale irrigation systems are characterized by low yields and deteriorating infrastructure. Interventions often erroneously focus on increasing yields and rehabilitating infrastructure. Small-scale irrigation systems have many of the characteristics of complex socio-ecological systems, with many different actors and numerous interconnected subsystems. However, the limited interaction between the different subsystems and their agents prevents learning and the emergence of more beneficial outcomes. This article reports on using Agricultural Innovation Platforms to create an environment in which irrigation scheme actors can engage, experiment, learn and build adaptive capacity to increase market-related offtake and move out of poverty.     

Design of experiment approach applied to reducing and oxidizing tolerance of anode supported solid oxide fuel cell. Part II: Electrical, electrochemical and microstructural characterization of tape-cast cells

One of the major limitations of the nickel (Ni) - yttria-stabilized zirconia (YSZ) anode support for solid oxide fuel cells (SOFC) is its low capability to withstand transients between reducing and oxidizing atmospheres (“RedOx” cycle), owing to the Ni-to-NiO volume expansion. This work presents results on different anode supports fabricated by tape casting. Three compositions are prepared, as the outcome of a preceding design of experiment approach. The NiO proportion is 40, 50 and 60 wt% of the anode composite.The anode support characteristics like shrinkage during sintering, in-situ conductivity at high temperature, electrochemical performance and tolerance against RedOx cycles have been measured. Performance up to 0.72 W cm⁻² (0.62 V, 800 °C) is recorded for the 60 wt% NiO sample on small cells. The open circuit voltage is maintained within ±5 mV after 10 full RedOx cycles at 800 °C and one at 850 °C. Performances tend to be stabilized after one or multiple RedOx cycles. The microstructural observations show round Ni particles after the first reduction; after a RedOx cycle, the Ni particles include micro-porosities that are stable under humidified reducing atmosphere for more than 300 h.