| 1. |
- Sumaila, U. Rashid, et al.
(författare)
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WTO must ban harmful fisheries subsidies
- 2021
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 374:6567, s. 544-544
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 2. |
- Han, Sang Sub, et al.
(författare)
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Peel-and-Stick Integration of Atomically Thin Nonlayered PtS Semiconductors for Multidimensionally Stretchable Electronic Devices
- 2022
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 14:17, s. 20268-20279
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Tidskriftsartikel (refereegranskat)abstract
- van der Waals (vdW) crystals with unparalleled electromechanical properties have been explored for transformative devices. Currently, the availability of 2D vdW crystals is rather limited in nature as they are only obtained from certain mother crystals with intrinsically possessed layered crystallinity and anisotropic molecular bonding. Recent efforts to transform conventionally non-vdW three-dimensional (3D) crystals into ultrathin 2D-like structures have seen rapid developments to explore device building blocks of unique form factors. Herein, we explore a "peel-and-stick" approach, where a nonlayered 3D platinum sulfide (PtS) crystal, traditionally known as a cooperate mineral material, is transformed into a freestanding 2D-like membrane for electromechanical applications. The ultrathin (???10 nm) 3D PtS films grown on large-area (>cm2) silicon dioxide/silicon (SiO2/Si) wafers are precisely "peeled" inside water retaining desired geometries via a capillary-force-driven surface wettability control. Subsequently, they are "sticked" on strain-engineered patterned substrates presenting prominent semiconducting properties, i.e., p-type transport with an optical band gap of ∼1.24 eV. A variety of mechanically deformable strain-invariant electronic devices have been demonstrated by this peel-and-stick method, including biaxially stretchable photodetectors and respiratory sensing face masks. This study offers new opportunities of 2D-like nonlayered semiconducting crystals for emerging mechanically reconfigurable and stretchable device technologies.
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| 3. |
- Jenniskens, Peter, et al.
(författare)
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The impact and recovery of asteroid 2018 LA
- 2021
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Ingår i: Meteoritics and Planetary Science. - : John Wiley & Sons. - 1086-9379 .- 1945-5100. ; 56:4, s. 844-893
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Tidskriftsartikel (refereegranskat)abstract
- The June 2, 2018 impact of asteroid 2018 LA over Botswana is only the second asteroid detected in space prior to impacting over land. Here, we report on the successful recovery of meteorites. Additional astrometric data refine the approach orbit and define the spin period and shape of the asteroid. Video observations of the fireball constrain the asteroid's position in its orbit and were used to triangulate the location of the fireball's main flare over the Central Kalahari Game Reserve. Twenty‐three meteorites were recovered. A consortium study of eight of these classifies Motopi Pan as an HED polymict breccia derived from howardite, cumulate and basaltic eucrite, and diogenite lithologies. Before impact, 2018 LA was a solid rock of ~156 cm diameter with high bulk density ~2.85 g cm−3, a relatively low albedo pV ~ 0.25, no significant opposition effect on the asteroid brightness, and an impact kinetic energy of ~0.2 kt. The orbit of 2018 LA is consistent with an origin at Vesta (or its Vestoids) and delivery into an Earth‐impacting orbit via the ν6 resonance. The impact that ejected 2018 LA in an orbit toward Earth occurred 22.8 ± 3.8 Ma ago. Zircons record a concordant U‐Pb age of 4563 ± 11 Ma and a consistent 207Pb/206Pb age of 4563 ± 6 Ma. A much younger Pb‐Pb phosphate resetting age of 4234 ± 41 Ma was found. From this impact chronology, we discuss what is the possible source crater of Motopi Pan and the age of Vesta's Veneneia impact basin.
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| 4. |
- Blomqvist, Mats, et al.
(författare)
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High-performance epitaxial Na0.5K0.5NbO3 thin films by magnetron sputtering
- 2002
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 81:2, s. 337-339
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Tidskriftsartikel (refereegranskat)abstract
- Epitaxial Na0.5K0.5NbO3 (NKN) thin films have been grown on LaAlO3 substrates by rf magnetron sputtering of a stoichiometric, high-density, ceramic target. X-ray diffraction analysis showed c-axis oriented cube-on-cube growth. Micrometer size interdigital capacitor (IDC) structures were defined on the surface of the NKN film using photolithography. The electrical characterization at 1 MHz showed dissipation factor tan delta of 0.010, tunability 16.5% at 200 kV/cm and dielectric permittivity epsilon(r)=470. The frequency dispersion of epsilon(r) between 1 kHz and 1 MHz was 8.5% and the IDCs showed very good insulating properties with leakage current density on the order of 30 nA/cm(2) at 400 kV/cm. The polarization loop exhibits weak ferroelectric hysteresis with maximum polarization 23.5 muC/cm(2) at 600 kV/cm. These results are promising for tunable microwave devices based on rf sputtered NKN thin films.
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| 5. |
- Khartsev, Sergiy, et al.
(författare)
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Comparative characteristics of Na0.5K0.5NbO 3 films on Pt by pulsed laser deposition and magnetron sputtering
- 2003
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Ingår i: Integrated Ferroelectrics. - : Informa UK Limited. - 1058-4587 .- 1607-8489. ; 55, s. 769-779
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Tidskriftsartikel (refereegranskat)abstract
- Ferroelectric Na0.5K0.5NbO3 (NKN) thin films were grown on the Pt80Ir20 polycrystalline substrates by pulsed laser deposition (PLD) and radio frequency-magnetron sputtering (RF) technique using the same stoichiometric Na0.5K 0.5NbO3 ceramic target. X-ray diffraction proved both PLD- and RF-made Na0.5K0.5NbOj/Pt80Ir20 films are single phase and have preferential c-axis orientation. Temperature dependence of dielectric permittivity reveals the presence of two phase transitions around 210 and 410°C. Capacitance vs. applied voltage C-V @ 100 kHz, I-V, and P-E hysteresis characteristics recorded for the vertical capacitive structures yielded loss tan δ = 0.026 and 0.016, tunability about 44.5 and 30% @ 100 kV/cm, Ohmic resistivity 6.7 × 1012 Ω·cm and 0.2 × 1012 Ω·cm, remnant polarization 11.7 and 9.7 μC/cm2, coercive field 28.0 and 94.6 kV/cm for PLD- and RF-films, respectively. Piezoelectric test carried out in hydrostatic conditions showed piezoelectric coefficient dH = 21 for PLD-NKN and 15 pC/N for RF-NKN film.
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| 6. |
- Yamashita, Andre S., et al.
(författare)
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A review of modeling and control strategies for cone crushers in the mineral processing and quarrying industries
- 2021
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Ingår i: Minerals Engineering. - : Elsevier. - 0892-6875 .- 1872-9444. ; 170
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Forskningsöversikt (refereegranskat)abstract
- Run-of-mine ore is usually too large to be useful for construction or metallurgy. Large particles must be reduced to specific sizes to either comply with aggregate sizing regulations, or facilitate mineral liberation; therefore, in the aggregates and mineral processing industries, run-of-mine ore is broken in crushing circuits by cone crushers. Here, we review the cone crusher literature, focusing on the modeling and control of crushing circuits. A total of 61 works published in the primary literature, ranging from 1972 to 2020, are classified and discussed with respect to the model formulation—i.e., population balance models, empirical models, or data-driven models—and control strategy—i.e., proportional-integral-derivative, model predictive control, expert system, or model-free control. The data are summarized in a table that makes locating a particular formulation or strategy quick and easy. The discussion of the current state of the art of crushing circuit modeling and control technologies consolidates the results available in the literature, as well as the challenges that we must overcome to increase crushing performance through control and optimization. The discussion of future trends brings attention to the discrete element method, model based control, plant-wide and mine-to-mill optimization, and machine learning applications for data acquisition and process optimization.
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