TiN nanoparticle reinforced AlSi10Mg composite powder was produced by a novel ultrasonic vibration dispersion technique. The TiN/AlSi10Mg composites were fabricated via selective laser melting (SLM). ...The effects of scanning speed on the microstructure, particle distribution state, and tribological properties of the as-built composites were studied. Experimental results showed a better SLM processibility for the composite powder due to the considerable improvement of laser absorption capacity. The microstructure of as-built composite parts was remarkably refined with a gradually decreased average grain size from 0.388 μm to 0.284 μm by increasing scanning speed compared to that of AlSi10Mg part (∼ 0.579 μm). Nano-sized TiN particles were evenly distributed and well-bonded in the composite matrix while minimized agglomerated TiN particles gathered and grew into large spherical clusters. Because of the in-situ reaction occurred between TiN cluster and AlSi10Mg matrix, novel graded interfacial layers were observed. The mean layer thickness increased from 0.11 μm to 0.38 μm by decreasing the scanning speed from 600 mm/s to 200 mm/s. Taking advantage of the dispersion strengthening, fine grain strengthening, and the graded interfacial layer, a considerably-high microhardness (145 ± 4.9 HV), and enhanced wear performance were achieved.
We perform large-eddy simulation of turbulent flow separation over an airfoil and evaluate the effectiveness of synthetic jets as a separation control technique. The flow configuration consists of ...flow over an NACA 0015 airfoil at Reynolds number of 896,000 based on the airfoil chord length and freestream velocity. A small slot across the entire span connected to a cavity inside the airfoil is employed to produce oscillatory synthetic jets. Detailed flow structures inside the synthetic-jet actuator and the synthetic-jet/cross-flow interaction are simulated using an unstructured-grid finite-volume large-eddy simulation solver. Simulation results are compared with the 2005 experimental data of Gilarranz et al., and qualitative and quantitative agreements are obtained for both uncontrolled and controlled cases. As in the experiment, the present large-eddy simulation confirms that synthetic-jet actuation effectively delays the onset of flow separation and causes a significant increase in the lift coefficient. Modification of the blade boundary layer due to oscillatory blowing and suction and its role in separation control is discussed.
Carbon nanotubes (CNTs) have lately attracted remarkable attention as reinforcements of materials because of their exceptional mechanical and electronic properties. However, studies on the ...ceramic–CNT composite have been rarely reported. Alumina–CNT composites have been produced to investigate the effect of carbon nanotube addition on the mechanical and tribological properties by hot-pressing. The alumina–CNT composite powder was prepared by catalytic pyrolysis of acetylene gas with an iron nitrate impregnated alumina. The contents of iron nitrate were controlled from 0 to 0.5
mol.% to change the CNT compositions in the alumina–CNT composite. The microstructures and mechanical properties of hot-pressed composites have been investigated to explain the effect of the CNT compositions on the tribological properties of the alumina reinforced with CNT composites.
In the present paper, we develop an electrostatic-thermodynamic-kinetic (ELTHEKI) model for studying the behavior of the specific
Ni
/
Ni
/
H
2
O
system, encountered in the pressurized water reactor ...(PWR) core. The ELTHEKI model proposes a coupled approach to describe the growth and dissolution/precipitation of the nickel oxide, under the PWR operating conditions (high temperature and alkaline
p
H). The electrostatic-thermodynamic-kinetic coupled modeling figures in the interfacial reaction kinetics, given by the modified Butler-Volmer (BV) law. It is expressed as a function of a composition gradient depending on the equilibrium concentration of the charge carrier, the interfacial potential drop, and the kinetic constant. Across the oxide film, nickel vacancies and holes are transported according to the Nernst-Planck (NP) equation, i.e., under concentration and potential gradients. Following the Point Defect Model (PDM), the electric field induced by charge carriers is assumed to be homogeneous within the oxide film. However, in the present study, the electric field is modeled using the Gauss law and the Helmholtz model, including also the potential drop of zero charge. Here, we propose a theoretical method for the calculation of the potential drop of zero charge at the oxide interfaces. Based on the energy band diagram, this work provides an electronic description of a metallic nickel in contact with a p-type nickel oxide, which are immersed in a liquid phase containing a redox couple. The thermodynamic aspect is also taken into account. It describes the flux between the nickel oxide and the primary fluid, driven by the deviation from an equilibrium state, which is imposed by the reactor variation conditions (
p
H, purification of the fluid, and temperature).
In this paper, we study the use of EEG (Electroencephalography) to classify between concentrated and relaxed mental states. In the literature, most EEG recording systems are expensive, medical-graded ...devices. The expensive devices limit the availability in a consumer market. The EEG signals are obtained from a toy-grade EEG device with one channel of output data. The experiments are conducted in two runs, with 7 and 10 subjects, respectively. Each subject is asked to silently recite a five-digit number backwards given by the tester. The recorded EEG signals are converted to time-frequency representations by the software accompanying the device. A simple average is used to aggregate multiple spectral components into EEG bands, such as α, β, and γ bands. The chosen classifiers are SVM (support vector machine) and multi-layer feedforward network trained individually for each subject. Experimental results show that features, with α+β+γ bands and bandwidth 4 Hz, the average accuracy over all subjects in both runs can reach more than 80% and some subjects up to 90+% with the SVM classifier. The results suggest that a brain machine interface could be implemented based on the mental states of the user even with the use of a cheap EEG device.
We observed the dramatic enhancement of the intrinsic spontaneous and stimulated emission as well as the ensuing suppression of defect-related green emission in Au-decorated ZnO microrods. A series ...of spectral experiments and theoretical analysis demonstrated an electron transfer assisted process by surface plasmon (SP) resonant coupling between the Au nanoparticles and ZnO. The mechanism indicates an approach to enhance the UV emission of ZnO through an extra excitation of visible light similar to that for the defect emission of ZnO. Based on the coupling mechanism, the externally enhanced ultraviolet lasing was further improved from 1.5 to 2.8-fold by adjusting the pumping power of the green light intensity in the Au/ZnO hybrid cavity. This research not only further confirms the SPR-assisted electron transfer process but also offers an approach to improve the intrinsic UV emission even for heavily-defected ZnO through visible light excitation
via
a nonlinear process.
A hybrid Au/ZnO microcavity was constructed and made the optical properties of the microcavity improve under single and multi-laser beam excitation because of LSP induced electron transfer. Utilizing this mechanism, we realized an even further improvement of the tunable lasing behavior through extra green light excitation.
Summary
Hepatitis B virus X protein (HBx) acts as a multifunctional protein that regulates intracellular signalling pathways during HBV infection. It has mainly been studied in terms of its ...interaction with cellular proteins. Here, we show that HBx induces membrane permeabilization independently of the mitochondrial permeability transition pore complex. We generated mitochondrial outer membrane‐mimic liposomes to observe the direct effects of HBx on membranes. We found that HBx induced membrane permeabilization, and the region comprising the transmembrane domain and the mitochondrial‐targeting sequence was sufficient for this process. Membrane permeabilization was inhibited by nonselective channel blockers or by N‐(n‐nonyl)deoxynojirimycin (NN‐DNJ), a viroporin inhibitor. Moreover, NN‐DNJ inhibited HBx‐induced mitochondrial depolarization in Huh‐7 cells. Based on the results of this study, we can postulate that the HBx protein itself is sufficient to induce mitochondrial membrane permeabilization. Our finding provides important information for a strategy of HBx targeting during HBV treatment.
Review of laser welding monitoring You, D. Y.; Gao, X. D.; Katayama, S.
Science and technology of welding and joining,
04/2014, Letnik:
19, Številka:
3
Journal Article
Recenzirano
Laser welding, as a highly efficient processing technology, has been widely applied to manufacturing industry. This paper makes an overview on real time monitoring of laser welding. It begins with a ...detailed introduction to six typical sensors (photodiode, visual, spectrometer, acoustical sensor, pyrometer, plasma charge sensor) in laser welding detection. Then it makes a review on multi-sensor fusion technology in both laser welding monitoring and adaptive control. Last, subjects for future research concerning welding monitoring and control have been proposed. The paper concludes that the real-time monitoring of laser welding can provide a great amount of valid information about welding status to help effectively identify weld defects and realize adaptive control.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
To investigate p16 effects on diffusion image metrics and associations with tumor progression in patients with locally advanced head and neck cancers.
Diffusion images pretreatment and after 20 Gy ...(2wk) of RT were analyzed in patients with cT4/N3 p16+ oropharynx cancer (OPSCC) (N=51) and locoregionally advanced head and neck squamous cell carcinoma (LAHNSCC) (N=28), enrolled onto a prospective adaptive RT trial. Mean ADC values, subvolumes with ADC <1.2 um
/ms (TV
), and peak values of low (µ
) and high (µ
) components of ADC histograms in primary and total nodal gross tumor volumes were analyzed for prediction of freedom from local, distant, or any progression (FFLP, FFDP or FFLRDP) using multivariate Cox proportional-hazards model with clinical factors. P value with false discovery control <0.05 was considered as significant.
With a mean follow up of 36 months, 18 of LAHNSCC patients and 16 of p16+ OPSCC patients had progression. After adjusting for p16, small µ
and ADC values, and large TV
of primary tumors pre-RT were significantly associated with superior FFLRDP, FFLP and FFDP in the LAHNSCC (p<0.05), but no diffusion metrics were significant in p16+ oropharynx cancers. Post
analysis of the p16+ OPSCC only showed that large TV
of the total nodal burden pre-RT was significantly associated with inferior FFDP (p=0.05).
ADC metrics were associated with different progression patterns in the LAHNSCC and p16+ OPSCC, possibly explained by differences in cancer biology and morphology. A deep understanding of ADC metrics is warranted to establish imaging biomarkers for adaptive RT in HNSCC.
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