133 research outputs found
SteBLife, a New Approach for the Accelerated Generation of Metallic Materialsâ Fatigue Data
The service life of materials and components exposed to repeated mechanical loads is
limited, which is why the understanding of the damage evolution and estimating its fatigue life is of
high importance for its technical application. This paper shows how temperature and magnetic field
measurement methods can be used to describe the cyclic deformation behaviour of metallic materials
and to derive parameters from this, which are used in short-term methods to calculate the fatigue
life. Within the SteBLife (stepped-bar fatigue life) approach, only three to five fatigue tests with a
stepped fatigue specimen are required to determine a complete SâN or Woehler curve with scatter
bands for different failure probabilities. If only a trend SâN curve is required, the number of tests
can be reduced to a single fatigue test only. In the framework of this paper, these approaches will be
presented for normalised SAE 1045 (C45E) and quenched and tempered SAE 4140 (42CrMo4) steels
Microstructure-Based Lifetime Assessment of Austenitic Steel AISI 347 in View of Fatigue, Environmental Conditions and NDT
The assessment of metallic materials used in power plantsâ piping represents a big challenge
due to the thermal transients and the environmental conditions to which they are exposed. At present,
a lack of information related to degradation mechanisms in structures and materials is covered by
safety factors in its design, and in some cases, the replacement of components is prescribed after a
determined period of time without knowledge of the true degree of degradation. In the collaborative
project âMicrostructure-based assessment of maximum service life of nuclear materials and components
exposed to corrosion and fatigue (MibaLeb)â, a methodology for the assessment of materialsâ degradation
is being developed, which combines the use of NDT techniques for materials characterization, an
optimized fatigue lifetime analysis using short time evaluation procedures (STEPs) and numerical
simulations. In this investigation, the AISI 347 (X6CrNiNb18-10) is being analyzed at different
conditions in order to validate the methodology. Besides microstructural analysis, tensile and fatigue
tests, all to characterize the material, a pressurized hot water pipe exposed to a series of flow
conditions will be evaluated in terms of full-scale testing as well as prognostic evaluation, where the
latter will be based on the materialsâ data generated, which should prognose changes in the materialâs
condition, specifically in a pre-cracked stage. This paper provides an overview of the program, while
the more materialâs related aspects are presented in the subsequent paper
A Short-Time Approach for Fatigue Life Evaluation of AISI 347 Steel for Nuclear Power Energy Applications
AISI 347 austenitic steel is, as an example, used in nuclear energy piping systems. Piping
filled with superheated steam or cooled water is particularly exposed to high stresses, whereupon
local material properties in the pipes can change significantly, especially in the case of additional
corrosive influences, leading to aging of the material. In the absence of appropriate information, such
local material property variations are currently covered rather blanketly by safety factors set during
the design of those components. An increase in qualified information could improve the assessment
of the condition of such aged components. As part of the collaborative project âMicrostructure-based
assessment of the maximum service life of core materials and components subjected to corrosion and
fatigue (MiBaLeB)â, the short-time procedure, StrainLife, was developed and validated by several
fatigue tests. With this procedure, a complete SâN curve of a material can be determined on the
basis of three fatigue tests only, which reduces the effort compared to a conventional approach
significantly and is thus ideal for assessing the condition of aged material, where the material is often
rare, and a cost-effective answer is often very needed. The procedure described is not just limited to
traditional parameters, such as stress and strain, considered in destructive testing but rather extends
into parameters derived from non-destructive testing, which may allow further insight into what
may be happening within a materialâs microstructure. To evaluate the non-destructive quantities
measured within the StrainLife procedure and to correlate them with the aging process in a material,
several fatigue tests were performed on unnotched and notched specimens under cyclic loading at
room and elevated temperatures, as well as under various media conditions, such as distilled water
and reactor pressure vessel boiling water (BWR) conditions
Sarcasm in written communication: emoticons are efficient markers of intention
Here we present two studies that investigate the use of emoticons in clarifying message intent. We look at sarcasm in particular, which can be especially hard to interpret correctly in written communication. In both studies, participants were required to make the intentions of their messages clear. In the first, they clarified the meaning of existing sentences without altering the wording; in the second, they produced their own sentences. Results provided clear evidence that tongue and wink emoticons are the principal indicators of sarcastic intent, and that ellipsis is associated more with criticism, rather than with sarcasm. These findings highlight the significant role emoticons play in clarifying message intention, compensating for the absence of non-verbal cues in written communicatio
Fine-mapping identifies multiple prostate cancer risk loci at 5p15, one of which associates with TERT expression
Associations between single nucleotide polymorphisms (SNPs) at 5p15 and multiple cancer types have been reported. We have previously shown evidence for a strong association between prostate cancer (PrCa) risk and rs2242652 at 5p15, intronic in the telomerase reverse transcriptase (TERT) gene that encodes TERT. To comprehensively evaluate the association between genetic variation across this region and PrCa, we performed a fine-mapping analysis by genotyping 134 SNPs using a custom Illumina iSelect array or Sequenom MassArray iPlex, followed by imputation of 1094 SNPs in 22 301 PrCa cases and 22 320 controls in The PRACTICAL consortium. Multiple stepwise logistic regression analysis identified four signals in the promoter or intronic regions of TERT that independently associated with PrCa risk. Gene expression analysis of normal prostate tissue showed evidence that SNPs within one of these regions also associated with TERT expression, providing a potential mechanism for predisposition to disease
Inhibition of angiogenesis by interleukin-4 gene therapy in rat adjuvant-induced arthritis
Objective Interleukin-4 (IL-4) can modulate neovascularization. In this study, we used a gene therapy approach to investigate the role of IL-4 in angiogenesis in rat adjuvant-induced arthritis (AIA), a model for rheumatoid arthritis. Methods Rats received an adenovirus producing IL-4 (AxCAIL-4), a control virus without insert, or control vehicle (phosphate buffered saline) intraarticularly before arthritis onset. At peak onset of arthritis, rats were killed. Vascularization was determined in the synovial tissue, and correlations with inflammation were assessed. Ankle homogenates were used in angiogenesis assays in vitro and in vivo, and protein levels of cytokines and growth factors were assessed by enzyme-linked immunosorbent assay. Synovial tissue expression of Îv integrins was determined by immunohistochemistry. Results IL-4 induced a reduction in synovial tissue vessel density, which was paralleled by a decrease in inflammation. AxCAIL-4 joint homogenates significantly ( P < 0.05) inhibited both endothelial cell (EC) migration and tube formation in vitro. Similarly, AxCAIL-4 inhibited capillary sprouting in the rat aortic ring assay, and vessel growth in the in vivo Matrigel plug assay. The angiostatic effect occurred despite high levels of vascular endothelial growth factor (VEGF), and was associated with down-regulation of the proangiogenic cytokines IL-18, CXCL16, and CXCL5 and up-regulation of the angiogenesis inhibitor endostatin. Of interest, AxCAIL-4 also resulted in decreased EC expression of the Îv and Î3 integrin chains. Conclusion In rat AIA, IL-4 reduces synovial tissue vascularization via angiostatic effects, mediates inhibition of angiogenesis via an association with altered pro- and antiangiogenic cytokines, and may inhibit VEGF-mediated angiogenesis and exert its angiostatic role in part via ÎvÎ3 integrin. This knowledge of the specific angiostatic effects of IL-4 may help optimize target-oriented treatment of inflammatory arthritis.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/55808/1/22034_ftp.pd
Online calculator for individual affiliation to a major population group
Because of their sensitivity and high level of discrimination, short tandem repeat (STR) maker systems are currently the method of choice in routine forensic casework and data banking, usually in multiplexes up to 15â17 loci. Constraints related to sample amount and quality, frequently encountered in forensic casework, will not allow to change this picture in the near future, notwithstanding the technological developments. In this study, we present a free online calculator named PopAffiliator (http://cracs.fc.up.pt/popaffiliator) for individual population affiliation in the three main population groups, Eurasian, East Asian and sub-Saharan African, based on genotype profiles for the common set of STRs used in forensics. This calculator performs affiliation based on a model constructed using machine learning techniques. The model was constructed using a data set of approximately fifteen thousand individuals collected for this work. The accuracy of individual population affiliation is approximately 86%, showing that the common set of STRs routinely used in forensics provide a considerable amount of information for population assignment, in addition to being excellent for individual identification
Thromboxane biosynthesis in cancer patients and its inhibition by aspirin: a sub-study of the Add-Aspirin trial
BACKGROUND: Pre-clinical models demonstrate that platelet activation is involved in the spread of malignancy. Ongoing clinical trials are assessing whether aspirin, which inhibits platelet activation, can prevent or delay metastases. METHODS: Urinary 11-dehydro-thromboxane B2 (U-TXM), a biomarker of in vivo platelet activation, was measured after radical cancer therapy and correlated with patient demographics, tumour type, recent treatment, and aspirin use (100âmg, 300âmg or placebo daily) using multivariable linear regression models with log-transformed values. RESULTS: In total, 716 patients (breast 260, colorectal 192, gastro-oesophageal 53, prostate 211) median age 61 years, 50% male were studied. Baseline median U-TXM were breast 782; colorectal 1060; gastro-oesophageal 1675 and prostate 826âpg/mg creatinine; higher than healthy individuals (~500âpg/mg creatinine). Higher levels were associated with raised body mass index, inflammatory markers, and in the colorectal and gastro-oesophageal participants compared to breast participants (Pâ<â0.001) independent of other baseline characteristics. Aspirin 100âmg daily decreased U-TXM similarly across all tumour types (median reductions: 77-82%). Aspirin 300âmg daily provided no additional suppression of U-TXM compared with 100âmg. CONCLUSIONS: Persistently increased thromboxane biosynthesis was detected after radical cancer therapy, particularly in colorectal and gastro-oesophageal patients. Thromboxane biosynthesis should be explored further as a biomarker of active malignancy and may identify patients likely to benefit from aspirin
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