This paper investigates the effect of temperature (between 24°C and 450°C) on the wear rate and friction coefficient of a high strength alloy steel (Super-CMV) in gross sliding fretting in air. It ...was found that whilst there was significant loss of material from the contact during fretting at room temperature, the overall loss of material from the contact had become negative even with a modest increase in temperature to 85°C. At temperatures greater than 85°C, negative wear was maintained, with the coefficient of friction dropping monotonically with increasing temperature up to 450°C. It is proposed that the changes in wear rate and friction coefficient were due to changes in the way that the oxide particles sintered to form a protective debris bed, with sintering of the oxide debris particles at these low temperatures being promoted by the nano-scale at which the oxide debris is formed.
•A significant reduction in fretting wear was found between 24°C and 85°C.•The COF reduced monotonically between 24°C and 450°C.•The reduction in wear is related to retention of debris within the contact.•The reduction in COF is commensurate with the formation of a glaze-layer.
Abstract
The re-emergence of stem rust on wheat in Europe and Africa is reinforcing the ongoing need for durable resistance gene deployment. Here, we isolate from wheat,
Sr26
and
Sr61
, with both ...genes independently introduced as alien chromosome introgressions from tall wheat grass (
Thinopyrum ponticum
). Mutational genomics and targeted exome capture identify
Sr26
and
Sr61
as separate single genes that encode unrelated (34.8%) nucleotide binding site leucine rich repeat proteins.
Sr26
and
Sr61
are each validated by transgenic complementation using endogenous and/or heterologous promoter sequences.
Sr61
orthologs are absent from current
Thinopyrum elongatum
and wheat pan genome sequences, contrasting with
Sr26
where homologues are present. Using gene-specific markers, we validate the presence of both genes on a single recombinant alien segment developed in wheat. The co-location of these genes on a small non-recombinogenic segment simplifies their deployment as a gene stack and potentially enhances their resistance durability.
Context. Magnetic bright points (MBPs) are dynamic, small-scale magnetic elements often found with field strengths of the order of a kilogauss within intergranular lanes in the photosphere. Aims. ...Here we study the evolution of various physical properties inferred from inverting high-resolution full Stokes spectropolarimetry data obtained from ground-based observations of the quiet Sun at disc centre. Methods. Using automated feature-tracking algorithms, we studied 300 MBPs and analysed their temporal evolution as they evolved to kilogauss field strengths. These properties were inferred using both the NICOLE and SIR Stokes inversion codes. We employ similar techniques to study radiative magnetohydrodynamical simulations for comparison with our observations. Results. Evidence was found for fast (∼30−100 s) amplification of magnetic field strength (by a factor of 2 on average) in MBPs during their evolution in our observations. Similar evidence for the amplification of fields is seen in our simulated data. Conclusions. Several reasons for the amplifications were established, namely, strong downflows preceding the amplification (convective collapse), compression due to granular expansion and mergers with neighbouring MBPs. Similar amplification of the fields and interpretations were found in our simulations, as well as amplification due to vorticity. Such a fast amplification will have implications for a wide array of topics related to small-scale fields in the lower atmosphere, particularly with regard to propagating wave phenomena in MBPs.
In humans and other mammals it is known that calcium and phosphate ions are secreted from the distal small intestine into the lumen. However, why this secretion occurs is unclear. Here, we show that ...the process leads to the formation of amorphous magnesium-substituted calcium phosphate nanoparticles that trap soluble macromolecules, such as bacterial peptidoglycan and orally fed protein antigens, in the lumen and transport them to immune cells of the intestinal tissue. The macromolecule-containing nanoparticles utilize epithelial M cells to enter Peyer's patches, small areas of the intestine concentrated with particle-scavenging immune cells. In wild-type mice, intestinal immune cells containing these naturally formed nanoparticles expressed the immune tolerance-associated molecule 'programmed death-ligand 1', whereas in NOD1/2 double knockout mice, which cannot recognize peptidoglycan, programmed death-ligand 1 was undetected. Our results explain a role for constitutively formed calcium phosphate nanoparticles in the gut lumen and show how this helps to shape intestinal immune homeostasis.
Many chemicals can induce skin sensitization, and there is a pressing need for non-animal methods to give a quantitative indication of potency. Using two large published data sets of skin ...sensitizers, we have allocated each sensitizing chemical to one of 10 mechanistic categories and then developed good QSAR models for the seven categories that have a sufficient number of chemicals to allow modeling. Both internal and external validation checks showed that each model had good predictivity.
Although CB(1) receptor activation evokes neuroprotection in response to cannabinoids, some cannabinoids have been reported to be peroxisome proliferator activated receptor (PPAR) ligands, offering ...an alternative protective mechanism. We have, therefore, investigated the ability of a range of cannabinoids to activate PPAR alpha and for N-oleoylethanolamine (OEA), an endogenous cannabinoid-like compound (ECL), to evoke neuroprotection.
Assays of PPAR alpha occupancy and gene transactivation potential were conducted in cell-free and transfected HeLa cell preparations, respectively. In vivo estimates of PPAR alpha activation through fat mobilization and gene transcription were conducted in mice. Neuroprotection in vivo was investigated in wild-type and PPAR alpha gene-disrupted mice.
The ECLs OEA, anandamide, noladin ether and virodhamine were found to bind to the purified PPAR alpha ligand binding domain and to increase PPAR alpha-driven transcriptional activity. The high affinity synthetic CB(1/2) cannabinoid agonist WIN 55212-2 bound to PPAR alpha equipotently with the PPARalpha agonist fenofibrate, and stimulated PPARalpha-mediated gene transcription. The phytocannabinoid delta 9 tetrahydrocannabinol was without effect. OEA and WIN 55212-2 induced lipolysis in vivo, while OEA pre-treatment reduced infarct volume from middle cerebral artery occlusion in wild-type, but not in PPAR alpha-null mice. OEA treatment also led to increased expression of the NFkappa B-inhibitory protein, Ikappa B, in mouse cerebral cortex, while expression of the NFkappa B-regulated protein COX-2 was inhibited.
These data demonstrate the potential for a range of cannabinoid compounds, of diverse structures, to activate PPAR alpha and suggest that at least some of the neuroprotective properties of these agents could be mediated by nuclear receptor activation.
The use of liver allografts from an older donor (OD) (age>50 years) is a widespread strategy to manage the disparity between supply and demand of organs for liver transplantation. This study ...determines the effect of OD allografts on fibrosis progression and graft survival after liver transplantation in patients with and without infection caused by hepatitis C virus (HCV).
All patients undergoing liver transplantation at our center from March 1998 to December 2001 were analyzed. Protocol liver biopsies were performed at 1, 16, and 52 weeks after transplantation and yearly thereafter. One liver pathologist scored all biopsy specimens for modified hepatic activity index (0-18) and fibrosis (0-6).
A total of 402 patients (167 with HCV and 235 without HCV) underwent liver transplantation during the study period. Among patients with HCV, baseline characteristics of OD recipients were similar to younger donor (YD) (age<50 years) recipients. In patients with HCV, graft survival was shorter in OD graft recipients than in YD recipients (P<0.001). In patients without HCV, graft survival was independent of donor age. In patients with HCV, a fibrosis score of 3 or greater was present in 17% of OD recipients at 4 months and in 26% at 12 months after transplantation, compared with 8% of YD recipients at 4 months and 13% at 12 months (P<0.001).
Liver transplantation with OD grafts is associated with rapid progression of fibrosis and decreased graft survival in patients with HCV, but not in patients without HCV. OD grafts should be considered preferentially for patients without HCV.
Annexin I protein expression was evaluated in patient-matched longitudinal study sets of laser capture microdissected normal, premalignant, and invasive epithelium from human esophageal squamous cell ...cancer and prostatic adenocarcinoma. In 25 esophageal cases (20 by Western blot and 5 by immunohistochemistry) and 17 prostate cases (3 by Western blot and 14 by immunohistochemistry), both tumor types showed either complete loss or a dramatic reduction in the level of annexin I protein expression compared with patient-matched normal epithelium (P < or = 0.05). Moreover, by using Western blot analysis of laser capture microdissected, patient-matched longitudinal study sets of both tumor types, the loss of protein expression occurred in premalignant lesions. Concordance of this result with immunohistochemical analysis suggests that annexin I may be an essential component for maintenance of the normal epithelial phenotype. Additional studies investigating the mechanism(s) and functional consequences of annexin I protein loss in tumor cells are warranted.
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