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排序方式: 共有581条查询结果,搜索用时 31 毫秒
1.
Ugur Gezer Ebru E. Y?rüker Metin Keskin Cemil Burak Kulle Yoganiranjana Dharuman Stefan Holdenrieder 《International journal of molecular sciences》2015,16(12):29654-29662
Circulating nucleic acids (CNAs) are under investigation as a liquid biopsy in cancer as potential non-invasive biomarkers, as stable structure in circulation nucleosomes could be valuable sources for detection of cancer-specific alterations in histone modifications. Our interest is in histone methylation marks with a focus on colorectal cancer, one of the leading cancers respective the incidence and mortality. Our previous work included the analysis of trimethylations of lysine 9 on histone 3 (H3K9me3) and of lysine 20 on histone 4 (H4K20me3) by chromatin immuno- precipitation-related PCR in circulating nucleosomes. Here we asked whether global immunologic measurement of histone marks in circulation could be a suitable approach to show their potential as biomarkers. In addition to H3K9me3 and H4K20me3 we also measured H3K27me3 in plasma samples from CRC patients (n = 63) and cancer free individuals (n = 40) by ELISA-based methylation assays. Our results show that of three marks, the amounts of H3K27me3 (p = 0.04) and H4K20me3 (p < 0.001) were significantly lower in CRC patients than in healthy controls. For H3K9me3 similar amounts were measured in both groups. Areas under the curve (AUC) in receiver operating characteristic (ROC) curves indicating the power of CRC detection were 0.620 for H3K27me3, 0.715 for H4K20me3 and 0.769 for the combination of both markers. In conclusion, findings of this preliminary study reveal the potential of blood-based detection of CRC by quantification of histone methylation marks and the additive effect of the marker combination. 相似文献
2.
Peter Demeester Burak Bilgin Patrick De Causmaecker Greet Vanden Berghe 《Journal of Scheduling》2012,15(1):83-103
Many researchers studying examination timetabling problems focus on either benchmark problems or problems from practice encountered
in their institutions. Hyperheuristics are proposed as generic optimisation methods which explore the search space of heuristics
rather than direct solutions. In the present study, the performance of tournament-based hyperheuristics for the exam timetabling
problem are investigated. The target instances include both the Toronto and ITC 2007 benchmarks and the examination timetabling
problem at KAHO Sint-Lieven (Ghent, Belgium). The Toronto and ITC 2007 benchmarks are post-enrolment-based examination timetabling
problems, whereas the KAHO Sint-Lieven case is a curriculum-based examination timetabling problem. We drastically improve
the previous (manually created) solution for the KAHO Sint-Lieven problem by generating a timetable that satisfies all the
hard and soft constraints. We also make improvements on the best known results in the examination timetabling literature for
seven out of thirteen instances for the To ronto benchmarks. The results are competitive with those of the finalists of the
examination timetabling track of the International Timetabling Competition. 相似文献
3.
As a renewable feedstock and due to its high functionality glycerol is an attractive reactant for the production of a large number of valuable compounds. We report on an environmentally friendly alternative to produce chemicals from the glycerol oxidation, which are currently produced either by stoichiometric oxidation processes or by enzymatic routes. We investigate the heterogeneously catalyzed liquid-phase oxidation of glycerol with carbon supported gold catalysts. The prepared nanosized gold catalysts are highly active, so that the reaction could be performed under atmospheric pressure. The influence of the preparation method of the catalysts has been investigated. Moreover, the support effect on the catalytic process has been studied and discussed in terms of pore structure of the investigated carbon materials. The promotor effect of platinum on Au/C catalysts was examined and it could be shown that the presence of Pt increases not only the catalyst activity but also the selectivity. By promoting the gold catalysts with platinum the selectivity to dihydroxyacetone could be increased from 26% (Au/C) to 36% (Au–Pt/C). 相似文献
4.
Flexible piezoresistive films, such as, carbon black/polydimethylsiloxane (C-PDMS) composites, are often used as skin analogs and integrated into complex array sensors for tactile sensing. The uniformity of the sensor characteristics heavily depends on the homogeneity of the composite. Therefore, the ability to locally characterize a film that will be integrated into a complex force sensor could be critical. Here, a method to characterize the local sensitivity of flexible piezoresistive films is presented. Using a conductive sphere, which was chosen over a flat probe to eliminate misalignment issues, the surface of a thin film composite is indented to characterize the change in resistivity in terms of average strain. Experiments were performed with 15 and 18 wt% carbon black C-PDMS films of varying thickness. The contact radius of the probe with the piezoresistive film was estimated using the Johnson-Roberts-Kendall contact theory. Theoretical contact area estimates were found to agree with contact radius measurements carried out using optically transparent PDMS films observed through an optical microscope. Results show that C-PDMS with 15 wt% carbon black exhibit a higher rate if change of resistivity and gauge factor than films of same thickness with 18 wt% carbon black. On the other hand, thicker films exhibit higher gauge factors for the two tested carbon black contents. Tests carried out at multiple locations yielded consistent sensitivity values, making these types of composites suitable for array type force sensors. 相似文献
5.
Bilal Demirel Nihat B. İnaner Derya U. Gezer Fugen Daver Ali Yaras Fatih Akkurt 《Polymer Engineering and Science》2021,61(7):2043-2054
Polyethylene terephthalate (PET)/nano-hydroxyapatite (nHAp) composite granules were obtained using twin-screw extruder. Preforms were prepared by injection molding and then PET/nHAp bottles were produced by blow molding. For PET bottles with nHAp, the migration amounts of carboxylic acid (COOH), acetaldehyde (AA), diethylene glycol (DEG), and isophthalic acid (IPA); glass transition temperature (Tg); melting temperature (Tm); and the maximum crystallization temperature (Tcry) were measured. The load-carrying capacity, burst strength, stress cracking, and regional material distribution tests were carried out on the bottles. X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, and ultraviolet transmittance analyses were conducted to explain the changes in mechanical, chemical, physical properties, and light transmission of bottles. It was found out that the COOH amount increased and the AA content decreased with increasing nHAp amount. On the other hand, no change was observed in the amounts of DEG and IPA. Although the mechanical properties such as load-carrying capacity and burst strength of the bottles have improved, it has been determined that the standard environmental stress crack resistance test procedure cannot be applied to such a composite. Experimental findings indicate that nHAp disrupts the chemical structure of PET and it isolates harmful chemicals such as AA by forming intermolecular bonds. Moreover, with the addition of up to 0.8% nHAp, PET bottles block the light transmission approximately 80% within 400–700 nm wave length zone. The study demonstrates that the PET/nHAp composite bottles can be used in the food industry, particularly in the packaging of milk and milk products which are vulnerable to light exposure. 相似文献
6.
V. S. Burak S. V. Volkov O. G. Martynenko P. P. Khramtsov I. A. Shikh 《Journal of Engineering Physics and Thermophysics》1994,67(3-4):848-853
We carried out an experimental investigation of free convective heat transfer on a vertical plate subjected to a constant heat flux in the presence of one or several rectangular steps. Temperature fields were investigated with the help of a Mach-Zehnder interferometer. During the experiment the Rayleigh number changed from zero to Ra=2.8·103. The flow was observed by the method of track visualization by means of a laser knife. Durectly behind a step we observed a circulating free convective flow having the shape of two oppositely rotating vortices.Academic Scientific Complex A. V. Luikov Heat and Mass Transfer Institute of the Academy of Sciences of Belarus, Minsk, Belarus. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 67, Nos. 3–4, pp. 190–196, September–October, 1994. 相似文献
7.
Biodegradable Microparticles for Simultaneous Detection of Counterfeit and Deteriorated Edible Products
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Ivan Rehor Sophie van Vreeswijk Tina Vermonden Wim E. Hennink Willem K. Kegel Huseyin Burak Eral 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(39)
In an era of globalized trade relations where food and pharmaceutical products cross borders effortlessly, consumers face counterfeit and deteriorated products at elevated rates. This paper presents multifunctional, biodegradable hydrogel microparticles that can provide information on the authenticity and the potential deterioration of the tagged food or pharmaceutical formulations. These microparticles integrate spatially patterned authenticity code with two sensors—the first one detects possible presence of pathogenic microbes through monitoring pH while the second one identifies products stored above optimal temperatures via optical monitoring of the microparticle degradation. Particles are synthesized from a biocompatible polymer and a photoinitiator, dextran modified with 2‐hydroxyethylmethacrylate and riboflavin, respectively, using a continuous, high throughput method stop‐flow lithography. The proposed synthesis approach also enables crosslinking with visible light bringing about additional flexibility to flow lithography. Model liquid and solid food and pharmaceutical products are successfully labeled with microparticles and the functionality of the sensors in aqueous solutions is demonstrated. 相似文献
8.
Cost estimation and effort allocation are the key challenges for successful project planning and management in software development.
Therefore, both industry and the research community have been working on various models and techniques to accurately predict
the cost of projects. Recently, researchers have started debating whether the prediction performance depends on the structure
of data rather than the models used. In this article, we focus on a new aspect of data homogeneity, “cross- versus within-application
domain”, and investigate what kind of training data should be used for software cost estimation in the embedded systems domain.
In addition, we try to find out the effect of training dataset size on the prediction performance. Based on our empirical
results, we conclude that it is better to use cross-domain data for embedded software cost estimation and the optimum training
data size depends on the method used. 相似文献
9.
Software cost/effort estimation is still an open challenge. Many researchers have proposed various methods that usually focus
on point estimates. Until today, software cost estimation has been treated as a regression problem. However, in order to prevent
overestimates and underestimates, it is more practical to predict the interval of estimations instead of the exact values.
In this paper, we propose an approach that converts cost estimation into a classification problem and that classifies new
software projects in one of the effort classes, each of which corresponds to an effort interval. Our approach integrates cluster
analysis with classification methods. Cluster analysis is used to determine effort intervals while different classification
algorithms are used to find corresponding effort classes. The proposed approach is applied to seven public datasets. Our experimental
results show that the hit rate obtained for effort estimation are around 90–100%, which is much higher than that obtained
by related studies. Furthermore, in terms of point estimation, our results are comparable to those in the literature although
a simple mean/median is used for estimation. Finally, the dynamic generation of effort intervals is the most distinctive part
of our study, and it results in time and effort gain for project managers through the removal of human intervention. 相似文献
10.
Sreedhar Ganapuram G.T. Vijaya Kumar I.V. Murali Krishna Ercan Kahya M. Cüneyd Demirel 《Advances in Engineering Software》2009,40(7):506-518
The objective of this study is to explore the groundwater availability for agriculture in the Musi basin. Remote sensing data and geographic information system were used to locate potential zones for groundwater in the Musi basin. Various maps (i.e., base, hydrogeomorphological, geological, structural, drainage, slope, land use/land cover and groundwater prospect zones) were prepared using the remote sensing data along with the existing maps. The groundwater availability of the basin is qualitatively classified into different classes (i.e., very good, good, moderate, poor and nil) based on its hydrogeomorphological conditions. The land use/land cover map was prepared for the Kharif season using a digital classification technique with the limited ground truth for mapping irrigated areas in the Musi basin. The alluvial plain in filled valley, flood plain and deeply buried pediplain were successfully delineated and shown as the prospective zones of groundwater. 相似文献