445 research outputs found
Heat Transfer and Friction Coefficients for Turbulent Flow of Air in Smooth Annuli at High Temperatures
Experimental local heat transfer and average friction coefficients for subsonic turbulent flow of air in an annulus at high temperatures
Hochtemperatur-Gaskuehlung fuer schnelle Brueter High temperature gas cooling for fast breeders
Rubber-enhanced polyamide nanofibers for a significant improvement of CFRP interlaminar fracture toughness
Nanofibrous mats provide substantial delamination hindering in composite laminates, especially if the polymer (as rubbers) can directly toughen the composite resin. Here, the well-known Nylon 66 nanofibers were impregnated with Nitrile Butadiene Rubber (NBR) for producing rubber/thermoplastic membranes for hampering the delamination of epoxy Carbon Fiber Reinforced Polymers (CFRPs). The starting polyamide mats were electrospun using two different solvent systems, and their effect on the mat's thermal and mechanical properties was investigated, as well as the laminate Mode I delamination resistance via Double Cantilever Beam (DCB) tests. Plain Nylon 66 mats electrospun from formic acid/chloroform perform better than the ones obtained from a solvent system containing trifluoroacetic acid, showing up to + 64% vs + 53% in interlaminar fracture toughness (GI), respectively. The effect of NBR coating benefits both nanofiber types, significantly raising the GI. The best results are obtained when interleaving medium-thickness and lightweight mats (20 µm, 9–10 g/m2) with 70–80 wt% of loaded rubber, achieving up to + 180% in GI. The work demonstrates the ability of NBR at improving the delamination hindering of common polyamide nonwovens, paving the way to the use of NBR-coated Nylon 66 nanofibers as effective interleaves for GI enhancement and overall composite safety improvement
Single Silver Nanoparticle instillation induced early and persisting moderate cortical damage in rat kidney
The potential toxic effects of silver nanoparticles (AgNPs), administered by a single
intratracheal instillation (i.t), was assessed in a rat model using commercial physico-chemical
characterized nanosilver. Histopathological changes, overall toxic response and oxidative stress
(kidney and plasma protein carbonylation), paralleled by ultrastructural observations (TEM),
were evaluated to examine renal responses 7 and 28 days after i.t. application of a low AgNP
dose (50 g/rat), compared to an equivalent dose of ionic silver (7 g AgNO3/rat). The AgNPs
caused moderate renal histopathological and ultrastructural alteration, in a region-specific manner,
being the cortex the most affected area. Notably, the bulk AgNO3, caused similar adverse effects
with a slightly more marked extent, also triggering apoptotic phenomena. Specifically, 7 days after
exposure to both AgNPs and AgNO3, dilatation of the intercapillary and peripheral Bowman\u2019s
space was observed, together with glomerular shrinkage. At day 28, these effects still persisted
after both treatments, accompanied by an additional injury involving the vascular component of
the mesangium, with interstitial micro-hemorrhages. Neither AgNPs nor AgNO3 induced oxidative
stress effects in kidneys and plasma, at either time point. The AgNP-induced moderate renal effects
indicate that, despite their benefits, novel AgNPs employed in consumer products need exhaustive
investigation to ensure public health safety
European helium cooled pebble bed (HCPB) test blanket. ITER design description document status 1.12.1996
Status report KfK contribution to the development of DEMO-relevant test blankets for NET/ITER. Part 2: BOT helium cooled solid breeder blanket. Vol. 1: Summary
Mass spectrometry of B. subtilis CopZ: Cu(I)-binding and interactions with bacillithiol
CopZ from Bacillus subtilis is a well-studied member of the highly conserved family of Atx1-like copper chaperones. It was previously shown via solution and crystallographic studies to undergo Cu(I)-mediated dimerisation, where the CopZ dimer can bind between one and four Cu(I) ions. However, these studies could not provide information about the changing distribution of species at increasing Cu(I) levels. To address this, electrospray ionisation mass spectrometry using soft ionisation was applied to CopZ under native conditions. Data revealed folded, monomeric CopZ in apo- and Cu(I)-bound forms, along with Cu(I)-bound dimeric forms of CopZ at higher Cu(I) loading. Cu4(CopZ)2 was the major dimeric species at loadings >1 Cu(I)/CopZ, indicating the cooperative formation of the tetranuclear Cu(I)-bound species. As the principal low molecular weight thiol in B. subtilis, bacillithiol (BSH) may play a role in copper homeostasis. Mass spectrometry showed that increasing BSH led to a reduction in Cu(I)-bound dimeric forms, and the formation of S-bacillithiolated apo-CopZ and BSH adducts of Cu(I)-bound forms of CopZ, where BSH likely acts as a Cu(I) ligand. These data, along with the high affinity of BSH for Cu(I), determined here to be β2(BSH) = ∼4 × 1017 M−2, are consistent with a role for BSH alongside CopZ in buffering cellular Cu(I) levels. Here, mass spectrometry provides a high resolution overview of CopZ–Cu(I) speciation that cannot be obtained from less discriminating solution-phase methods, thus illustrating the potential for the wider application of this technique to studies of metal–protein interactions
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