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Purpose: The introduction of aquatic animals into paddy fields is an effective strategy to improve rice yields and mitigate greenhouse gas emissions. However, it remains unclear how rice-animal co-culture systems affect methane (CH4) and nitrous oxide (N2O) emissions and rice yields, and the comprehensive drivers of management practices and pedo-climatic conditions have not been evaluated. Methods: A meta-analysis of 247 pairwise comparisons was employed to compare the CH4 and N2O emissions and rice yield between rice-animal co-culture (i.e., rice-duck, rice-fish, rice-crayfish, rice-crab, and rice-frog systems) and rice monoculture. Results: The results demonstrated that rice-animal co-culture significantly alleviated CH4 emission by 86.8%, improved rice yield by 49.2%, and had no significant effects on N2O emission relative to rice monoculture. Rice-animal co-culture was found to reduce the global warming potential by 12.9% and the greenhouse gas intensity by 4.9%. Considering rice yield improvement and greenhouse gas mitigation, the rice-duck, rice-fish, and rice-frog modes had great advantages over the rice-crayfish and rice-crab modes. Additionally, the effects of rice-animal co-culture on CH4 and N2O emissions and the rice yield were found to differ with the co-culture mode, aquatic animal density, feeding, nitrogen fertilizer rate, number of nitrogen applications, soil texture, soil pH, air temperature, and precipitation. Conclusion: Rice-animal co-culture systems have the great potential to increase agricultural productivity and alleviate environmental risks, which deserves to be acceptable and sustainable. [ABSTRACT FROM AUTHOR]

Recently, chalcogenide phase-change materials have been widely applied in phase-change random access memory. However, the materials still have shortcomings of poor stability and low crystalline resistivity, causing high-power consumption, resistance drift, and short device life in phase-change random access memory. These do not meet the technical requirements and need to be modified. To improve Sb-Te systems alloy materials' properties and discover new phase-change materials, in this work, we construct 16 solid-solution systems based on SbTe (Sb1−xNMx)Te and Sb(Te1−xNMx) (NM = noble metals). We use a high-throughput computing method to calculate and analyze the underlying physical mechanism of solid-solution noble metal atoms' effects on improving the performance of phase-change materials. Based on the calculation results, we believe that the (Sb1−xNMx)Te solid solutions are more stable than Sb(Te1−xNMx). At the same time, the solid solution of the substituted Sb atom sites keeps the crystal structure symmetry improved structural stability. Furthermore, lone-pair electrons exist due to (Sb1−xNMx)Te keeping the SbTe's unique layer structure, which confers a higher activity of the surrounding atoms. This is an essential determinant for keeping the phase-change properties. On the other hand, (Sb1−xNMx)Te solid solutions increase the band gap, leading to increased resistivity. Considering the structural stability and electrical properties, we believe that the (Sb1−xRux) and (Sb1−xPdx)Te systems can create new phase-change materials. [ABSTRACT FROM AUTHOR]

Mobile crowdsensing (MCS) has been an effective sensing paradigm by exploiting the pervasive sensor-rich mobile devices for sensor data collection. Online task assignment is an important issue for mobile crowdsensing since tasks typically arrive dynamically and need to be handled in an online manner. In this paper, we study online task assignment for maximizing the total profit of the MCS platform while satisfying the time window requirement of each task. We first describe the crowdsensing model and then study the online task assignment in the following two different scenarios: (1) user-offline-arriving scenario, where all users are fully available throughout the whole sensing period and their movements are fully planned by the platform; (2) user-online-arriving scenario, where users arrive and depart dynamically and each user has a specific participatory time window for task executions. For the former scenario, we propose a benchmark algorithm and also an online heuristic algorithm. The benchmark algorithm tries to provide a best-case performance by assuming all future task arrival information is known in advance. The online algorithm adopts bipartite-matching-based strategy for task assignment and further performs minimal detour based data offloading for reducing the data upload cost, whenever possible. For the latter scenario, we propose an effective online algorithm, which adopts a maximum-profit-first strategy for task assignment and also minimal detour based data offloading for reduction of data upload cost whenever applicable. For all the proposed algorithms, we present their detailed design and deduce their time complexities. Extensive simulations are conducted and the results demonstrate that our proposed algorithms can largely increase the total profit of the platform as compared with existing work. [ABSTRACT FROM AUTHOR]

As a strong climate element on interannual scales, the El Nino-Southern Oscillation (ENSO) is a major component of global weather and climate change, and it is also closely related to the interannual atmospheric angular momentum (AAM) and length-of-day changes (ΔLOD). Here, we reprocess and compare the interannual variations of AAM, ΔLOD with ENSO indices, with AAM mass and motion terms calculated over land separately from those over the ocean. Three oscillatory components (at ~ 6, ~ 7, ~ 8 years), due to angular momentum changes in Earth's interior, are removed to obtain the interannual ΔLOD solely related to climatic variations. Our results show that the AAM motion term over the ocean contributes the most to interannual ΔLOD, and that the oceanic AAM has larger variability than that over land, especially during the periods of strong ENSO events. After subtracting contributions associated with interior processes, the interannual ΔLOD anomalies corresponding to extreme ENSO events (1982–1983 ~ 0.43, 1997–1998 ~ 0.36, 2015–2016 ~ 0.42 ms) are about half as strong as those found in previous studies (~ 0.91, ~ 0.76, ~ 0.81 ms). Furthermore, we detect an intermediate La Nina event that occurred from August 2020 to May 2021, forcing the interannual ΔLOD to a minimum value of approximately -0.21 ms. [ABSTRACT FROM AUTHOR]

Phase-change random access memory is regarded as the most promising candidate for storage class memory, which must be further improved by employing more competitive phase-change materials. In the present work, solid solutions combined with noble metals and Sb2Te3 were investigated by first-principles high-throughput calculations. The microstructures and properties of NMx(Sb2Te3)1−x (NM = noble metals) solid solutions are closely related to the compositions and solid solubility of NM composition. By changing the kind of NM composition, NMx(Sb2Te3)1−x solid solutions can present different properties, including transition temperature, short-range order, and thermal stability. The contributions of NM-nd states to electronic structures in Sb2(Te1−xNMx)3 solid solutions are much greater than Sb-5p and Te-5p states and even greater for (Sb1−xNMx)2Te3 solid solutions. Combining the results of energy, structure, stability, and electronic structure, (Sb1−xIrx)2Te3 solid solutions stand out as the best candidate for phase-change materials. [ABSTRACT FROM AUTHOR]

Mobile crowdsensing has become a new way to perceive and collect information due to the widespread of smart devices. In this paper, we study the task assignment problem in mobile crowdsensing systems, which is aimed to reducing the average and largest makespan of all tasks. We consider scenarios where task requester needs the help of mobile users for task completion when they encounter directly or through AP cloud (i.e., several APs connected via wired/wireless links) in an opportunistic manner. We describe the mobile crowdsensing system and formulate the problems under study. We first derive the conditional expected encountering time between requester and different users by jointly considering the opportunities via direct encountering and indirect encountering via AP cloud. Then we propose an AP-assisted average makespan sensitive online task assignment (AP-AOTA) algorithm and an AP-assisted largest makespan sensitive online task assignment (AP-LOTA) algorithm. We present detailed design for both algorithms. We deduce the computational complexities of both algorithms to be O(mn2), where m represents the number of tasks and n represent the number of users. We conduct simulations on a real trace data set and a synthetic trace data set and the results show that our proposed algorithms significantly outperform existing work. [ABSTRACT FROM AUTHOR]

The bacterial cellulose (BC)/AlO nanofibrous composite membrane as a lithium-ion battery separator has been successfully prepared by coating AlO on the BC nanofibers through a simple in situ thermal decomposition of Al(NO) · 9HO. Thermal treatment tests show that the BC/AlO composite membrane is thermally stable at a high temperature of 200 °C while great shrinkage is observed for the commercial PP-PE-PP membrane. Moreover, the BC/AlO membrane is evaluated to have large porosity and excellent electrolyte uptake, consequently giving rise to larger ionic conductivity, lower interfacial resistance as well as better electrochemical stability. The half lithium-ion battery assembled with the BC/AlO separator demonstrates large discharge capacity and good cycling performance, suggesting that the BC/AlO membrane can be used as a lithium-ion battery separator. [ABSTRACT FROM AUTHOR]

The developments of flexible supercapacitors are of great importance to the growing demand of portable electronic products. In the present work, we have successfully prepared bacterial cellulose (BC) membranes coated by polypyrrole (PPy) and copper oxide (CuO) as flexible composite electrodes for supercapacitor applications. The highest electrical conductivity value of 7.4 S cm was achieved using copper acetate aqueous solution with concentration of 1 wt%. Electrochemical measurements proved that the supercapacitors using the PPy/CuO/BC electrodes had a specific capacitance of 601 F g with an energy density of 48.2 Wh kg and a power density of 85.8 W kg at a current density of 0.8 mA cm. The specific capacitance was kept at 385 F g after 300 cycles. The introduction of the CuO nanoparticles gave rise to the improved capacitance. [ABSTRACT FROM AUTHOR]

The increasing trend of portable electronic products requires the development of portable and flexible energy-storage devices, such as flexible supercapacitors. In this study, we deposited polypyrrole (PPy) and nickel sulfide (NiS) on bacterial cellulose (BC) nanofibrous membranes to be used as flexible supercapacitor electrodes. The obtained PPy/NiS/BC composite membranes are highly conductive, with the electrical conductivity up to 5.1 S cm. Electrochemical measurements showed that the supercapacitors based on the PPy/NiS/BC electrodes have a high specific capacitance of 713 F g with a power density of 39.5 W kg and an energy density of 239.0 Wh kg at a current density of 0.8 mA cm. With increasing current density from 0.2 to 1.6 mA cm, the corresponding capacitance changes from 884 to 569 F g. The presence of NiS is found to considerably improve the capacitance performance. [ABSTRACT FROM AUTHOR]