5,946 research outputs found
Electron localization and magnetism in SrRuO\u3csub\u3e3\u3c/sub\u3e with non-magnetic cation substitution
The destruction of the ferromagnetism of alloyed SrRuO3 can be caused by electron localization at the substitution sites. Among all the non-magnetic cations that enter the B site, Zr4+ is the least disruptive to conductivity and ferromagnetism. This is because Zr4+ does not cause any charge disorder, and its empty d electron states which are poorly matched in energy with the Ru t2g4 states cause the least resonance scattering of Ru’s d electrons. Conducting Sr(Ru, Zr)O3 may be used as an electrode for perovskite-based thin film devices, while its insulating counterpart provides unprecedented magnetoresistance, seldom seen in other non-manganite and non-cobaltite perovskites.
(Some figures in this article are in colour only in the electronic version
Impacts of the seasonal distribution of rainfall on vegetation productivity across the Sahel
Climate change in drylands has caused alterations in the seasonal
distribution of rainfall including increased heavy-rainfall events, longer
dry spells, and a shifted timing of the wet season. Yet the aboveground net
primary productivity (ANPP) in drylands is usually explained by
annual-rainfall sums, disregarding the influence of the seasonal distribution
of rainfall. This study tested the importance of rainfall metrics in the wet
season (onset and cessation of the wet season, number of rainy days, rainfall
intensity, number of consecutive dry days, and heavy-rainfall events) for
growing season ANPP. We focused on the Sahel and northern Sudanian region
(100–800 mm yr−1) and applied daily satellite-based rainfall
estimates (CHIRPS v2.0) and growing-season-integrated normalized difference
vegetation index (NDVI; MODIS) as a proxy for ANPP over the study period:
2001–2015. Growing season ANPP in the arid zone
(100–300 mm yr−1) was found to be rather insensitive to
variations in the seasonal-rainfall metrics, whereas vegetation in the
semi-arid zone (300–700 mm yr−1) was significantly impacted by
most metrics, especially by the number of rainy days and timing (onset and
cessation) of the wet season. We analysed critical breakpoints for all
metrics to test if vegetation response to changes in a given rainfall metric
surpasses a threshold beyond which vegetation functioning is significantly
altered. It was shown that growing season ANPP was particularly negatively
impacted after  > 14 consecutive dry days and that a rainfall intensity of
 ∼ 13 mm day−1 was detected for optimum growing season ANPP.
We conclude that the number of rainy days and the timing of the wet season
are seasonal-rainfall metrics that are decisive for favourable vegetation
growth in the semi-arid Sahel and need to be considered when modelling
primary productivity from rainfall in the drylands of the Sahel and
elsewhere
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Effect of graphite on copper bioleaching fromwaste printed circuit boards
The efficient extraction of copper as a valuable metal from waste printed circuit boards (WPCBs) is currently attracting growing interest. Here, we systematically investigated the impact of bacteria on the efficiency of copper leaching from WPCBs, and evaluated the effect of graphite on bioleaching performance. The HQ0211 bacteria culture containing Acidithiobacillus ferrooxidans, Ferroplasma acidiphilum, and Leptospirillum ferriphilum enhanced Cu-leaching performance in either ferric sulfate and sulfuric acid leaching, so a final leaching of up to 76.2% was recorded after 5 days. With the addition of graphite, the percentage of copper leaching could be increased to 80.5%. Single-factor experiments confirmed the compatibility of graphite with the HQ0211 culture, and identified the optimal pulp density of WPCBs, the initial pH, and the graphite content to be 2% (w/v), 1.6, and 2.5 g/L, respectively.</jats:p
On the design of reliable hybrid wired-wireless network-on-chip architectures
With the ever increase in transistor density over technology scaling, energy and performance aware hybrid wire- less Network-on-Chip (WiNoC) has emerged as an alternative solution to the slow conventional wireline NoC design for future System-on-Chip (SoC). However, combining wireless and wireline channels drastically reduces the total reliability of the commu- nication fabric. Besides being lossy, existing feasible wireless solution for WiNoCs, which is in the form of millimeter wave (mm-Wave), relies on free space signal radiation which has high power dissipation with high degradation rate in the signal strength per transmission distance. Alternatively, low power wireless communication fabric in the form of surface wave has been proposed for on-chip communication. With the right design considerations, the reliability and performance benefits of the surface wave channel could be extended. In this paper, we propose a surface wave communication fabric for emerging WiNoCs that is able to match the channel reliability of traditional wireline NoCs. Here, a carefully designed transducer and commercially available thin metal conductor coated with a low cost dielectric material are employed to general surface wave signal to improve the wireless signal transmission gain. Our experimental results demonstrate that, the proposed communication fabric can achieve a 5dB operational bandwidth of about 60GHz around the center frequency (60GHz). By improving the transmission reliability of wireless layer, the proposed communication fabric can improve maximum sustainable load of NoCs by an average of 20.9% and 133.3% compared to existing WiNoCs and wireline NoCs, respectively
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