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101.
Sara Bagherifard Gianluca Roscioli Maria Vittoria Zuccoli Mehdi Hadi Gaetano D’Elia Ali Gökhan Demir Barbara Previtali Ján Kondás Mario Guagliano 《Journal of Thermal Spray Technology》2017,26(7):1517-1526
Cold spray offers the possibility of obtaining almost zero-porosity buildups with no theoretical limit to the thickness. Moreover, cold spray can eliminate particle melting, evaporation, crystallization, grain growth, unwanted oxidation, undesirable phases and thermally induced tensile residual stresses. Such characteristics can boost its potential to be used as an additive manufacturing technique. Indeed, deposition via cold spray is recently finding its path toward fabrication of freeform components since it can address the common challenges of powder-bed additive manufacturing techniques including major size constraints, deposition rate limitations and high process temperature. Herein, we prepared nickel-based superalloy Inconel 718 samples with cold spray technique and compared them with similar samples fabricated by selective laser melting method. The samples fabricated using both methods were characterized in terms of mechanical strength, microstructural and porosity characteristics, Vickers microhardness and residual stresses distribution. Different heat treatment cycles were applied to the cold-sprayed samples in order to enhance their mechanical characteristics. The obtained data confirm that cold spray technique can be used as a complementary additive manufacturing method for fabrication of high-quality freestanding components where higher deposition rate, larger final size and lower fabrication temperatures are desired. 相似文献
102.
103.
The multivariate calibration methods—principal component regression and partial least squares—were employed for the prediction of antioxidant capacities of fruit juices. High-performance liquid chromatography and spectrophotometric approaches were used to determine the antioxidant capacities of fruit juices. The importance of calibration design was investigated by calculating the prediction and validation errors. The influences of using independent validation sets were emphasized. Calibration design is shown to have major effect on principal component regression and partial least squares errors. The models developed on the basis of the mean-centered data were able to predict the total antioxidant activity with a precision comparable to that of the reference [2,2-azino-di-(3-ethylbenzothialozine-sulfonic acid)] method. The partial least squares model seems preferable because of its predictive and describing abilities and good interpretability of the contribution of compounds to the antioxidant capacity. The contribution of individual phenolic compounds to the antioxidant capacity was identified by high-performance liquid chromatography. 相似文献
104.
Handan Engin Kırımlı Kagan Sarlar A. Oguz Konuk Nagehan Duman M. Vedat Akdeniz Ilker Kucuk 《Journal of Superconductivity and Novel Magnetism》2013,26(5):1683-1685
In this study, the effects of Cu, Zr, Ti, Y, Pt substitution for Nb additions on the stability and magnetic properties of Fe-Ni-based bulk metallic glass (BMG) alloys fabricated by the suction casting method are investigated. The saturation magnetization (J s) and coercivity (H c) for as-cast Fe36Ni36B19.2Si4.8Nb4?x M x (M=Cu, Ti) BMG alloys were in the range of 0.51 T–0.55 T and 76–779 A/m, respectively. Differential scanning calorimetry curves show that the Fe36Ni36B19.2Si4.8Nb4?x M x (M=Cu, Ti) bulk metallic glasses have a supercooled liquid region for Cu at 44 K and for Ti at 39 K. 相似文献
105.
Halil Demir 《The International Journal of Advanced Manufacturing Technology》2008,35(9-10):1041-1046
An extensive study was performed in finish turning of the following microalloyed steels: as received (14.3 HRc), water-cooled (44.9 HRc), air-cooled (14.41 HRc) and furnace-cooled (9.1 HRc). The turning tests were carried out using multi-layer coated cemented carbide tools at four different cutting speeds (60, 90, 120, and 150 m/min) while feedrate and depth of cut were kept constant at 0.1 mm/rev and 1 mm, respectively. The influences of workpiece microstructure and cutting speed on cutting forces and workpiece surface roughness were investigated. The worn parts of the cutting tools were also examined under a scanning electron microscope (SEM). The results showed that cutting speed significantly affected the machined surface roughness values. However, cutting forces were not influenced significantly by workpiece microstructure and cutting speed except for water cooled specimen. 相似文献
106.
Nihat Sinan Isik Vedat Doyuran Resat Ulusay 《Bulletin of Engineering Geology and the Environment》2008,67(3):293-304
The deformation modulus of intact rock can be determined through standardized laboratory tests for heavily jointed rock masses
but this is very difficult, while in situ tests are time-consuming and expensive. In this study, the deformation modulus of
selected heavily jointed, sheared and/or blocky, weathered, weak greywacke, andesite and claystone were assessed, based on
pressuremeter tests, geo-engineering characterization and seismic surveys. Empirical equations based on GSI and RMR values
are proposed to indirectly estimate the deformation modulus of the greywackes. For the andesites, the spacing of the discontinuities
is greater than the length of the pressuremeter probe hence the intact rather than rock mass deformation modulus is obtained.
The pressuremeter test results from the claystones could not be correlated with the field data; the relationship between the
ratio of rock mass modulus to intact rock modulus and RQD appears to give a better estimation of the deformation modulus.
相似文献
107.
Halil İbrahim Ulusoy Ramazan Gürkan Özlem Demir Songül Ulusoy 《Food Analytical Methods》2012,5(3):454-463
A new method has been developed for preconcentration of cobalt at trace levels in beverage samples using calcon carboxylic
acid as chelating agent and cetyl pyridinium chloride as an auxiliary ligand and entrapped into Triton X-114 prior to its
determination by flame atomic absorption spectrometry (FAAS). The main parameters affecting cloud point extraction (CPE) efficiency
such as pH, concentration of the complexing agent, cationic and nonionic surfactant concentration, salt effect, the equilibrium
time, and temperature were investigated and optimized. After optimization of the CPE conditions, a preconcentration factor
of 60, an enhancement factor of 106, and a detection limit of 0.20 μg L−1 by (R
2 = 0.9978) were obtained from a calibration curve constructed in the range of 0.7–100 μg L−1. The proposed preconcentration procedure was successfully applied to the determination of cobalt ions in some real samples
including natural drinking water, tap water, and beer and wine samples. The accuracy and validity of the proposed CPE/FAAS
method was tested by means of five repeated analysis of reference standard materials (TM-253, a low level fortified water
standard for trace elements). A good agreement between analytical results (28.8 and 28.5 μg L−1 with calibration curve and standard addition curve method, respectively) and certified value (27.9 μg L−1) for Co (p < 0.05) were obtained and verified by means of calibration curve and standard addition curve method using CPE procedure. 相似文献
108.
Morphology-tailored synthesis of tungsten trioxide (hydrate) thin films and their photocatalytic properties 总被引:2,自引:0,他引:2
Tungsten trioxide hydrate (3WO(3)·H(2)O) films with different morphologies were directly grown on fluorine doped tin oxide (FTO) substrate via a facile crystal-seed-assisted hydrothermal method. Scanning electron microscopy (SEM) analysis showed that 3WO(3)·H(2)O thin films composed of platelike, wedgelike, and sheetlike nanostructures could be selectively synthesized by adding Na(2)SO(4), (NH(4))(2)SO(4), and CH(3)COONH(4) as capping agents, respectively. X-ray diffraction (XRD) studies indicated that these films were of orthorhombic structure. The as-prepared thin films after dehydration showed obvious photocatalytic activities. The best film grown using CH(3)COONH(4) as a capping agent generated anodic photocurrents of 1.16 mA/cm(2) for oxidization of methanol and 0.5 mA/cm(2) for water splitting with the highest photoconversion efficiency of about 0.3% under simulated solar illumination. 相似文献
109.
Nano-Micro Letters - In this investigation, the structural and electrical properties of nanocomposites of polyaniline (PANI) and cobalt ferrite synthesized by hydrothermal route are reported for... 相似文献
110.
Ari E Kaya Y Demir H Cebi A Alp HH Bakan E Odabasi D Keskin S 《Hemodialysis international. International Symposium on Home Hemodialysis》2011,15(4):453-459
Oxidative stress is accepted as a nonclassical cardiovascular risk factor in chronic renal failure patients. The aim of this study was to evaluate the relation between oxidative DNA damage (8‐hydroxy‐2′‐deoxyguanosine/deoxyguanosine [8‐OHdG/dG] ratio), oxidative stress biomarkers, antioxidant enzymes, and carotid artery intima‐media thickness (CIMT) in hemodialysis (HD) patients. Forty chronic HD patients without known atherosclerotic disease and 48 age‐ and sex‐matched healthy individuals were included in the study. Plasma malondialdehyde (MDA) levels and 8‐OHdG/dG ratio were determined as oxidative stress markers. Superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities were measured as antioxidants. CIMT was assessed by carotid artery ultrasonography. 8‐OHdG/dG ratios and MDA levels were higher; SOD and GPx activities were lower in HD patients compared to controls. HD patients had significantly higher CIMT compared to controls (0.61 ± 0.08 vs. 0.42 ± 0.05, p < 0.001). There was a significant positive correlation between CIMT and 8‐OHdG/dG ratio (r = 0.57, p < 0.01) and MDA levels (r = 0.41, p < 0.01), while there was a significant negative correlation between CIMT and SOD (r = ?0.47, p < 0.01) and GPx levels (r = ?0.62, p < 0.01). It is firstly demonstrated that CIMT is positively correlated with oxidative DNA damage in HD patients without known atherosclerotic disease. 相似文献