95 research outputs found
High temperature tribological characterization of TiAl laser cladding coating on Ti6Al4V alloy
Ti6Al4V alloy has proven to be an important engineering material due to the excellent
strength, weight ratio, high corrosion resistance and biocompatibility. However, the
alloy is susceptible to mechanical degradation in applications involving sliding wear
or abrasion. In order to improve wear resistance, coatings by laser cladding of
intermetallic Ti48Al2Cr2Nb on Ti6Al4V have been developed. Different process
parameters: laser power (W), scanning speed (mm/min), powder feeding rate (g/min)
and preheating temperature of substrate (°C) were optimized, resulting in a
microstructure of the coatings considered appropriate, with good metallurgical bond,
though cracks and pores were observed [1]. The composition and microstructure of
the coatings were evaluated using optical microscopy (OM), scanning electron
microscopy (SEM) and X-ray diffraction (XRD) analysis, further the tribological
properties were evaluated using a ball on disk tribometer, with Al2O3 ball, constant
speed of 0.1 m/s, 10 N load at room temperature and 500 °C. We measure the 3D
surface topography obtained from the wear scar and calculated the wear rate. The
coatings microstructure consists of -TiAl phase and 2-Ti3Al. The wear test results at
room temperature show a lower wear rate for the coating compared to the substrate.
At high temperature the coating have a higher friction coefficient and a higher rate of
wear is obtained when compared with the substrate, obtaining differences between
the coatings depending on the wear mechanism observed in the worn surface.The authors acknowledge the economical support from the Ministry of Science and
Innovation of the Government of Spain through research project MAT2011-28492-03
and the Generalitat Valenciana through support ACOMP/2014/151. Thanks also to
Dr. José Luis Jorda by X-ray diffraction analysis performed
Sex differences in pain expressed by patients across diverse disease states: individual patient data meta-analysis of 33,957 participants in 10 randomized controlled trials
The experience of pain is determined by many factors and has a significant impact on quality of life. This study aimed to determine sex differences in pain prevalence and intensity reported by participants with diverse disease states in several large international clinical trials. Individual participant data meta-analysis was conducted using EuroQol-5 Dimension (EQ-5D) questionnaire pain data from randomised controlled trials published between January 2000 and January 2020 and undertaken by investigators at the George Institute for Global Health. Proportional odds logistic regression models, comparing pain scores between females and males and fitted with adjustments for age and randomized treatment, were pooled in a random-effects meta-analysis. In 10 trials involving 33,957 participants (38% females) with EQ-5D pain score data, the mean age ranged between 50 and 74. Pain was reported more frequently by females than males (47% vs 37%; P < 0.001). Females also reported greater levels of pain than males (adjusted odds ratio 1.41, 95% CI 1.24-1.61; P < 0.001). In stratified analyses, there were differences in pain by disease group (P for heterogeneity <0.001), but not by age group or region of recruitment. Females were more likely to report pain, and at a higher level, compared with males across diverse diseases, all ages, and geographical regions. This study reinforces the importance of reporting sex-disaggregated analysis to identify similarities and differences between females and males that reflect variable biology and may affect disease profiles and have implications for management
Laser Cladding of TiC for Better Titanium Components
Pure commercial titanium is widely used because of its high corrosion resistance and lower cost compared with other titanium alloys, in particular when there is no high wear requirements. Nevertheless, the wear resistance is poor and surface damage usually occurs in areas under contact loadings. Laser cladding is a suitable technique for manufacturing precise and defect free coatings of a dissimilar material with higher wear and corrosion resistance. In this work a good understanding of laser metal deposition mechanisms allowed to obtain defect free coatings of Ti6Al4V and TiC metal matrix composite (MMC) using a flash lamp pumped Nd:YAG laser of 1 kW. A complete investigation of the process parameters is discussed and resultant wear properties are shown. The results show the feasibility to apply the process for manufacturing, improving or repairing high added value components for a wide range of industrial sectors. © 2011 Published by Elsevier Ltd.Sampedro, J.; Pérez, I.; Cárcel González, B.; Ramos, JA.; Amigó Borrás, V. (2011). Laser Cladding of TiC for Better Titanium Components. Physics Procedia. 12(Part A):313-322. doi:10.1016/j.phpro.2011.03.040S31332212Part
The effect of ultrasound pretreatment on some selected physicochemical properties of black cumin (Nigella Sativa)
Background
In the present study, the effects of ultrasound pretreatment parameters including irradiation time and power on the quantity of the extracted phenolic compounds quantity as well as on some selected physicochemical properties of the extracted oils including oil extraction efficiency, acidity and peroxide values, color, and refractive index of the extracted oil of black cumin seeds with the use of cold press have been studied.
Methods
For each parameter, three different levels (30, 60, and 90 W) for the ultrasound power and (30, 45, and 60 min) and for the ultrasound irradiation time were studied. Each experiment was performed in three replications.
Results
The achieved results revealed that, with enhancements in the applied ultrasound power, the oil extraction efficiency, acidity value, total phenolic content, peroxide value, and color parameters increased significantly (P 0.05).
Conclusions
In summary, it could be mentioned that the application of ultrasound pretreatment in the oil extraction might improve the oil extraction efficiency, the extracted oil’s quality, and the extracted phenolic compounds content.info:eu-repo/semantics/publishedVersio
Results of the BiPo-1 prototype for radiopurity measurements for the SuperNEMO double beta decay source foils
The development of BiPo detectors is dedicated to the measurement of
extremely high radiopurity in Tl and Bi for the SuperNEMO
double beta decay source foils. A modular prototype, called BiPo-1, with 0.8
of sensitive surface area, has been running in the Modane Underground
Laboratory since February, 2008. The goal of BiPo-1 is to measure the different
components of the background and in particular the surface radiopurity of the
plastic scintillators that make up the detector. The first phase of data
collection has been dedicated to the measurement of the radiopurity in
Tl. After more than one year of background measurement, a surface
activity of the scintillators of (Tl) 1.5
Bq/m is reported here. Given this level of background, a larger BiPo
detector having 12 m of active surface area, is able to qualify the
radiopurity of the SuperNEMO selenium double beta decay foils with the required
sensitivity of (Tl) 2 Bq/kg (90% C.L.) with a six
month measurement.Comment: 24 pages, submitted to N.I.M.
Expression analysis of carbohydrate antigens in ductal carcinoma in situ of the breast by lectin histochemistry
<p>Abstract</p> <p>Background</p> <p>The number of breast cancer patients diagnosed with ductal carcinoma <it>in situ </it>(DCIS) continues to grow. Laboratory and clinical data indicate that DCIS can progress to invasive disease. Carbohydrate-mediated cell-cell adhesion and tumor-stroma interaction play crucial roles in tumorigenesis and tumor aggressive behavior. Breast carcinogenesis may reflect quantitative as well as qualitative changes in oligosaccharide expression, which may provide a useful tool for early detection of breast cancer. Because tumor-associated carbohydrate antigens (TACA) are implicated in tumor invasion and metastasis, the purpose of this study was to assess the expression of selected TACA by lectin histochemistry on DCIS specimens from the archival breast cancer tissue array bank of the University of Arkansas for Medical Sciences.</p> <p>Methods</p> <p>For detection of TACA expression, specimens were stained with <it>Griffonia simplicifolia </it>lectin-I (GS-I) and <it>Vicia vilosa </it>agglutinin (VVA). We studied associations of lectin reactivity with established prognostic factors, such as tumor size, tumor nuclear grade, and expression of Her-2/neu, p53 mutant and estrogen and progesterone receptors.</p> <p>Results</p> <p>We observed that both lectins showed significant associations with nuclear grade of DCIS. DCIS specimens with nuclear grades II and III showed significantly more intense reactivity than DCIS cases with nuclear grade I to GS-1 (Mean-score chi-square = 17.60, DF = 2; <it>P </it>= 0.0002) and VVA (Mean-score chi-square = 15.72, DF = 2; <it>P </it>= 0.0004).</p> <p>Conclusion</p> <p>The results suggest that the expression of VVA- and GS-I-reactive carbohydrate antigens may contribute to forming higher grade DCIS and increase the recurrence risk.</p
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