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Nickel on two-dimensional ITQ-2 zeolite as a highly active catalyst for carbon dioxide reforming of methane
No full textThe physicochemical properties of the support material are important parameters that determine the activity and stability of supported metal catalysts in chemical reactions. In this study, we investigated the influence of the support dimensionality and nickel loading (5, 15, and 30 wt%) of supported-Ni catalysts for the carbon dioxide reforming of methane (CDR) by comparing the three-dimensional (3D) Ni/MCM-22 and its delaminated two-dimensional (2D) Ni/ITQ-2 catalyst. Owing to its delaminated nature, Ni/ITQ-2 exhibited a large external surface area (319 m(2) g(-1)) and a high proportion of the nickel phyllosilicate phase, even for 30 wt% Ni loading. In addition, the strong interaction of Ni clusters with phyllosilicate resulted in a high dispersion of Ni. The 2D Ni/ITQ-2 catalysts generally exhibited a higher catalytic performance than the 3D Ni/MCM-22 catalysts. The relative proportion of the nickel phyllosilicate phase in the catalyst also played a promoting role in achieving a high catalytic performance for CDR. Unlike Ni/gamma-Al2O3, Ni/ITQ-2 exhibited high conversions of CH4 and CO2, regardless of pre-reduction, which is advantageous for catalyst handling
A Direct-Current Triboelectric Nanogenerator Energy Harvesting System Based on Water Electrification for Self-Powered Electronics
No full textThis study aimed to develop a simple but effective mechanical-to-electrical energy conversion for harvesting hydrokinetic energy based on triboelectric nanogenerator (TENG) technology. Here, a direct-current fluid-flow-based TENG is reported as a potential solution to solve the inconvenience of directly powering electronic devices where direct-current (DC) power is required. The falling of a water droplet (about 1.06 mL) from an elastomeric pipe can generate an open-circuit voltage of ~35 V, short-circuit current of 3.7 mu A, and peak power of 57.6 mu W by passing through a separated electrode. Notably, the electrical responses have the distinct characteristics of pulsed direct current. The ability to generate DC outputs enables the TENG to directly drive electronic devices. Our experimental results prove that this TENG can act as a power source to directly light up 50 light-emitting diodes without requiring a rectifier, and, also, the produced electric energy was demonstrated that can be stored directly in a capacitor to power commercial temperature and humidity IoT sensors. Furthermore, the device shows a greatly varied output voltage based on the droplet flow rate, with a linearity R-2 = 0.998. This work highlights a promising potential for applications in harvesting hydrokinetic energy and self-powered sensors and systems
Controlling the rate of degradation of Mg using magnesium fluoride and magnesium fluoride-magnesium phosphate duplex coatings
No full textThe thin and porous Fluoride Conversion Coating FCC with many cracks could not offer a significant improvement in corrosion resistance for Mg. Magnesium phosphate coating improves the corrosion resistance of Mg, good bioactivity, promotes cell viability and cyto-compatibility and exhibits antibacterial activity. However, rapid dissolution in Mg in acidic magnesium phosphate containing solutions leads to the development of an inhomogeneous coating. The present study attempts to prevent the excessive dissolution of Mg by forming a fluoride conversion coating as a pre-treatment in the first stage followed by deposition of magnesium phosphate coating in the second stage to develop magnesium fluoride-magnesium phosphate duplex coatings. The morphological features, structural characteristics, nature of functional groups, corrosion behavior in Hanks' balanced salt solution and bioactivity in simulated body fluid are assessed to ascertain the suitability of the magnesium fluoride-magnesium phosphate duplex coating in controlling the rate of degradation of Mg and improving its bioactivity using uncoated Mg and fluoride conversion coated Mg as reference. The findings of the study reveal that the magnesium fluoride-magnesium phosphate duplex coating could offer an excellent corrosion resistance and improve the bioactivity of Mg. (C) 2021 Chongqing University. Publishing services provided by Elsevier B.V. on behalf of KeAi Communications Co. Ltd
Corrosion Behavior of Neutron Absorber Borated Stainless Steel in Simulated Spent Fuel Pool Environment
No full textEffect of Water Chemistry Changes on Irradiation Assisted Stress Corrosion Cracking Behavior of Stainless Steels in Primary Water Environment
No full textEffect of Physical Vapor Deposition Parameters on Coating Roughness and Adhesive Force for Lead cooled Fast Reactor Structure
No full textTAROGE-M: radio antenna array on antarctic high mountain for detecting near-horizontal ultra-high energy air showers
No full textAbstract The TAROGE-M radio observatory is a self-triggered antenna array on top of the ???2700 m high Mt. Melbourne in Antarctica, designed to detect impulsive geomagnetic emission from extensive air showers induced by ultra-high energy (UHE) particles beyond 1017 eV, including cosmic rays, Earth-skimming tau neutrinos, and particularly, the ???ANITA anomalous events??? (AAE) from near and below the horizon. The six AAE discovered by the ANITA experiment have signal features similar to tau neutrinos but that hypothesis is in tension either with the interaction length predicted by Standard Model or with the flux limits set by other experiments. Their origin remains uncertain, requiring more experimental inputs for clarification. The detection concept of TAROGE-M takes advantage of a high altitude with synoptic view toward the horizon as an efficient signal collector, and the radio quietness as well as strong and near vertical geomagnetic field in Antarctica, enhancing the relative radio signal strength. This approach has a low energy threshold, high duty cycle, and is easy to extend for quickly enlarging statistics. Here we report experimental results from the first TAROGE-M station deployed in January 2020, corresponding to approximately one month of livetime. The station consists of six receiving antennas operating at 180-450 MHz, and can reconstruct source directions of impulsive events with an angular resolution of ???0.3??, calibrated in situ with a drone-borne pulser system. To demonstrate TAROGE-M's ability to detect UHE air showers, a search for cosmic ray signals in 25.3-days of data together with the detection simulation were conducted, resulting in seven identified candidates. The detected events have a mean reconstructed energy of 0.95-0.31+0.46 EeV and zenith angles ranging from 25?? to 82??, with both distributions agreeing with the simulations, indicating an energy threshold at about 0.3 EeV. The estimated cosmic ray flux at that energy is 1.2-0.9+0.7 ?? 10-16 eV-1 km-2 yr-1 sr-1, also consistent with results of other experiments. The TAROGE-M sensitivity to AAEs is approximated by the tau neutrino exposure with simulations, which suggests comparable sensitivity as ANITA's at around 1 EeV energy with a few station-years of operation. These first results verified the station design and performance in a polar and high-altitude environment, and are promising for further discovery of tau neutrinos and AAEs after an extension in the near future
Constraints on dark photon dark matter using data from LIGO's and Virgo's third observing run
No full textWe present a search for dark photon dark matter that could couple to gravitational-wave interferometers using data from Advanced LIGO and Virgo's third observing run. To perform this analysis, we use two methods, one based on cross-correlation of the strain channels in the two nearly aligned LIGO detectors, and one that looks for excess power in the strain channels of the LIGO and Virgo detectors. The excess power method optimizes the Fourier transform coherence time as a function of frequency, to account for the expected signal width due to Doppler modulations. We do not find any evidence of dark photon dark matter with a mass between m(A) similar to 10(-14)-10(-11) eV/c(2), which corresponds to frequencies between 10-2000 Hz, and therefore provide upper limits on the square of the minimum coupling of dark photons to baryons, i.e., U(1)(B) dark matter. For the cross-correlation method, the best median constraint on the squared coupling is similar to 1.31 x 10(-47) at m(A) similar to 4.2 x 10(-13) eV/c(2); for the other analysis, the best constraint is similar to 2.4 x 10(-47) at m(A) similar to 5.7 x 10(-13) eV/c(2). These limits improve upon those obtained in direct dark matter detection experiments by a factor of similar to 100 for m(A) similar to [2-4] x 10(-13) eV/c(2), and are, in absolute terms, the most stringent constraint so far in a large mass range m(A) similar to 2 x 10(-13) - 8 x 10(-12) eV/c(2)
Photoluminescence and Energy Transfer in Double- and Triple-Lanthanide-Doped YVO4 Nanoparticles
No full textOptical materials doped with several lanthanides are unique in their properties and are widely used in various fields of science and technology. The study of these systems provides solutions for noncontact thermometry, bioimaging, sensing technology, and others. In this paper, we report on the demonstration of YVO4 nanoparticles doped with one, two, and three different rare earth ions (Tm3+, Er3+, and Nd3+). We discuss the morphology, structural properties, and luminescence behavior of particles. Luminescence decay kinetics reveal the energy transfer efficiency (up to 78%) for different ions under the selective excitation of individual ions. Thus, we found that the energy transition from Tm3+ is more favorable than from Er3+ while we did not observe any significant energy rearrangement in the samples under the excitation of Nd3+. The observed strong variation of REI lifetimes makes the suggested nanoparticles promising for luminescent labeling, anticounterfeiting, development of data storage systems, etc
On the Polarisation of Radio Relics
No full textRadio relics are extended radio emission features which trace shock waves in the periphery of galaxy clusters originating from cluster mergers. Some radio relics show a highly polarised emission, which make relics an excellent probe for the magnetisation of the intra-cluster medium. The origin of the relic polarisation is still debated. It could be a result of tangentially stretching the magnetic field at the shock surface. This scenario would naturally explain the alignment of the polarisation (E-vectors) with the shock normal. We have implemented a toy model for the relic polarisation according to this scenario. We find that the magnetic field strength itself crucially affects the fractional polarisation. Moreover, we find that the shock strength has surprisingly little effect on the overall polarisation fraction. Finally, we find that the fractional polarisation may decrease downstream depending on the magnetic field strength. Our results demonstrates that the shock compression scenario provides a very plausible explanation for the radio relic polarisation which specific features permitting to test the origin of radio relic polarisation