Realization of ferroelectric semiconductors by conjoining ferroelectricity with semiconductors remains a challenging task because most present-day ferroelectric materials are unsuitable for such a ...combination due to their wide bandgaps. Herein, we show first-principles evidence toward the realization of a new class of two-dimensional (2D) ferroelectric semiconductors through covalent functionalization of many prevailing 2D materials. Members in this new class of 2D ferroelectric semiconductors include covalently functionalized germanene, and stanene (Nat. Commun. 2014, 5, 3389), as well as MoS2 monolayer (Nat. Chem. 2015, 7, 45), covalent functionalization of the surface of bulk semiconductors such as silicon (111) (J. Phys. Chem. B 2006, 110 , 23898), and the substrates of oxides such as silica with self-assembly monolayers (Nano Lett. 2014, 14, 1354). The newly predicted 2D ferroelectric semiconductors possess high mobility, modest bandgaps, and distinct ferroelectricity that can be exploited for developing various heterostructural devices with desired functionalities. For example, we propose applications of the 2D materials as 2D ferroelectric field-effect transistors with ultrahigh on/off ratio, topological transistors with Dirac Fermions switchable between holes and electrons, ferroelectric junctions with ultrahigh electro-resistance, and multiferroic junctions for controlling spin by electric fields. All these heterostructural devices take advantage of the combination of high-mobility semiconductors with fast writing and nondestructive reading capability of nonvolatile memory, thereby holding great potential for the development of future multifunctional devices.
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IJS, KILJ, NUK, PNG, UL, UM
Electrical manipulation of skyrmions attracts considerable attention for its rich physics and promising applications. To date, such a manipulation is realized mainly via spin-polarized current based ...on spin-transfer torque or spin-orbital torque effect. However, this scheme is energy consuming and may produce massive Joule heating. To reduce energy dissipation and risk of heightened temperatures of skyrmion-based devices, an effective solution is to use electric field instead of current as stimulus. Here, we realize an electric-field manipulation of skyrmions in a nanostructured ferromagnetic/ferroelectrical heterostructure at room temperature via an inverse magneto-mechanical effect. Intriguingly, such a manipulation is non-volatile and exhibits a multistate feature. Numerical simulations indicate that the electric-field manipulation of skyrmions originates from strain-mediated modification of effective magnetic anisotropy and Dzyaloshinskii-Moriya interaction. Our results open a direction for constructing low-energy-dissipation, non-volatile, and multistate skyrmion-based spintronic devices.
The dimensionless thermoelectric figure of merit (ZT) in bismuth antimony telluride (BiSbTe) bulk alloys has remained around 1 for more than 50 years. We show that a peak ZT of 1.4 at 100°C can be ...achieved in a p-type nanocrystalline BiSbTe bulk alloy. These nanocrystalline bulk materials were made by hot pressing nanopowders that were ball-milled from crystalline ingots under inert conditions. Electrical transport measurements, coupled with microstructure studies and modeling, show that the ZT improvement is the result of low thermal conductivity caused by the increased phonon scattering by grain boundaries and defects. More importantly, ZT is about 1.2 at room temperature and 0.8 at 250°C, which makes these materials useful for cooling and power generation. Cooling devices that use these materials have produced high-temperature differences of 86°, 106°, and 119°C with hot-side temperatures set at 50°, 100°, and 150°C, respectively. This discovery sets the stage for use of a new nanocomposite approach in developing high-performance low-cost bulk thermoelectric materials.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Long-term rotary tillage limit water infiltration and crop productivity in North China Plain (NCP). The practice of subsoiling to fracture plow pans has made beneficial impacts on soil surface ...structure and water infiltration. Further, appropriate irrigation method coupled with irrigation regime can improve crop productivity in subsoiling condition. A three-year field trial (2020–2023) was carried out to assess the effects of the irrigation regime and the method on winter wheat evapotranspiration (ET), grain yield (GY), water productivity (WP), partial factor productivity from applied nitrogen (PPFN), and economic analysis. The three irrigation regimes were irrigated when soil moisture levels decreased to 70%, 60% and 50% of the field capacity (referred as H, M and L) and two irrigation methods were the surface drip irrigation (SDI) and the micro-sprinkler irrigation (MSI). The traditional flood irrigation with 70% of the field capacity in subsoiling filed was CK. The results showed optimizing irrigation method and irrigation regime significantly influenced ET, GY, WP, PPFN, and net incomes. As the irrigation amount increased, the ET first increased while GY, WP, PPFN, and net incomes increased and then slightly decreased. Based on the three-year average, the maximum GY of 9454 kg ha−1 and the net income of 11089 yuan ha−1 was achieved in SDI-M, which had WP of 2.3 kg m−3 and PPFN of 39.4 kg kg−1. At the same time, SDI-M did not result in much increase of ET (average of 405.1 mm in three seasons). Considering comprehensively ET, GY, WP, PPFN, and net incomes, to irrigate when soil moisture decreases to 60% of the field capacity by surface drip irrigation was the optimal strategy in all aspects. These results will provide a scientific reference for irrigation management in subsoiling wheat field in NCP, as well as in similar production areas worldwide.
●The performance of irrigation methods and regimes within subsoiling wheat fields was evaluated.●Surface drip irrigation promoted water productivity and nitrogen partial factor productivity relative to micro-sprinkler irrigation.●Surface drip irrigation produced the higher grain yield and net benefit in comparison to micro-sprinkler irrigation.●The TOPSIS designated the coupled surface drip irrigation and 60% FC as best.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Traditional mode conversion ultrasonic motors are typically composed of the superposition of multiple vibration modes, making them more complex than single-mode ultrasonic motors. This complexity ...makes it difficult to miniaturize. A micro radial-torsional vibration mode ultrasonic motor is proposed and tested in this work. It is excited by a single-phase excitation signal. The proposed motor utilizes the radial in-plane vibration mode of the stator to convert the torsional vibration mode of the inner ring through the beams. The torsional vibration of the inner ring causes the rotor to rotate due to the friction force between the inner ring and the rotor. Based on the designed structure and verified using the finite element method, a prototype motor with a mass of 2.6 g and overall dimensions of Ô20 mm in diameter and 15 mm in height is fabricated and characterized. During the mechanical output performance test, the prototype achieved a maximum no-load speed of 3300 r/min and a stall torque of 0.2 mN<inline-formula> <tex-math notation="LaTeX">\cdot </tex-math></inline-formula>m at the driving voltage of 100 V<inline-formula> <tex-math notation="LaTeX">_{\mathrm {p-p}} </tex-math></inline-formula>.
In order to explore the efficient use of water and nitrogen for winter wheat under irrigation with micro-sprinkling hose, two-season field experiments were conducted to evaluate the effects of ...irrigation levels and nitrogen application rate on yield, water productivity (WP) and nitrogen partial factor productivity (NPFP). Three irrigation levels were 60 %, 65 %, and 70 % field capacity (FC) during the reviving to jointing stage, 65 %, 70 %, and 75 % FC after the jointing stage, referred to as W1, W2 and W3, respectively. The irrigating water quota is 30 mm. The five N topdressing period treatments were reviving period + booting stage (N1), jointing + booting stage (N2), reviving period (N3), jointing stage (N4), and booting stage (N5). The results showed that the water consumption, leaf area index, plant height, biomass, grain yield, and NPFP increased with an increase in irrigation amount, and the WP decreased with an increase in irrigation amount. Nitrogen applied during the reviving period was beneficial for increasing grain yield, WP, and NPFP under the irrigation level W1; nitrogen applied during the jointing period was beneficial for increasing grain yield, WP, and NPFP for winter wheat under the W2 and W3 irrigation levels. The W3N2 treatment resulted in the highest grain yield (8.98 t·ha−1), but it was not significant difference from W2N2 (average of 8.92 t·ha−1). After a comprehensive evaluation based on grain yield, WP and NPFP, the appropriate modes of irrigation and nitrogen is the treatment of W2N2 (65 % and 70 % FC irrigation treatments during the reviving to jointing stage and the stages after jointing stage, respectively; the nitrogen topdressing during jointing + booting stage) for winter wheat using micro-sprinkling hose irrigation in North China.
•Yield and nitrogen use efficiency of winter wheat increased with the amount of irrigation (≤180 mm).•N topdressing at jointing and booting stage under W2 irrigation treatment obtained the highest yield.•Water and N use efficiency improved through optimizing micro-sprinkling hose irrigation and fertilizer management.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Accurate and timely crop yield prediction over large spatial regions is critical to national food security and sustainable agricultural development. However, designing a robust model for crop yield ...prediction over a large spatial region remains challenging due to inadequate surveyed samples and an under-development of deep-learning frameworks. To tackle this issue, we integrated multi-source (remote sensing, weather, and soil properties) data into a dual-stream deep-learning neural network model for winter wheat in China’s major planting regions. The model consists of two branches for robust feature learning: one for sequential data (remote sensing and weather series data) and the other for statical data (soil properties). The extracted features by both branches were aggregated through an adaptive fusion model to forecast the final wheat yield. We trained and tested the model by using official county-level statistics of historical winter wheat yields. The model achieved an average R2 of 0.79 and a root-mean-square error of 650.21 kg/ha, superior to the compared methods and outperforming traditional machine-learning methods. The dual-stream deep-learning neural network model provided decent in-season yield prediction, with an error of about 13% compared to official statistics about two months before harvest. By effectively extracting and aggregating features from multi-source datasets, the new approach provides a practical approach to predicting winter wheat yields at the county scale over large spatial regions.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
In order to identify different kinds of coal, rock, and gangue, the FPV integrated image transmission camera is used to collect images of 6 types of coal, 8 types of rocks, and 2 types of coal ...gangue, and the images are processed based on the two-dimensional discrete wavelet transform (2D-DWT) based on the steerable pyramid decomposition (SPD). The maximum likelihood estimation method is used to estimate the parameters, and, the coal and rock types are judged by comparing the similarity of each image. The results show the following: (1) in the eight kinds of rocks, the recognition accuracy of shale and limestone is 90%, that of anorthosite is 95%, and those of other rocks are 100%; (2) the accuracy of comprehensive identification of coal, rock, and gangue is 93%, the comprehensive of coal and gangue is 78%, and the rock classification is 97%; (3) the identification time of 6 types of coal samples, 8 types of rock samples, and 2 types of coal gangue samples are in the range of 2 s∼3 s, which is far less than 10 s, which can meet the requirements of coal and rock identification in terms of recognition speed; and (4) according to 20 groups of data, the range, variance, and standard deviation of the same coal gangue sample meet the accuracy requirements of coal and rock identification. The identification method provides an effective method to improve the efficiency of coal separation, effectively determine the distribution of coal and rock, and timely adjust the cutting height of shearer drum and the operation parameters of various fully mechanized mining equipment, so as to improve the recovery rate of coal resources.
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DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
Drought reduces leaf stomatal conductance (g
) and mesophyll conductance (g
). Both hydraulic signals and chemical signals (mainly abscisic acid, ABA) are involved in regulating g
. However, it ...remains unclear what role the endogenous ABA plays in g
under decreasing soil moisture. In this study, the responses of g
and g
to ABA were investigated under progressive soil drying conditions and their impacts on net photosynthesis (A
) and intrinsic water use efficiency (WUE
) were also analyzed. Experimental tomato plants were cultivated in pots in an environment-controlled greenhouse. Reductions of g
and g
induced a 68-78% decline of A
under drought conditions. While soil water potential (Ψ
) was over -1.01 MPa, g
reduced as leaf water potential (Ψ
) decreased, but ABA and g
kept unchanged, which indicating g
was more sensitive to drought than g
. During Ψ
reduction from -1.01 to -1.44 MPa, Ψ
still kept decreasing, and both g
and g
decreased concurrently following to the sustained increases of ABA content in shoot sap. The g
was positively correlated to g
during a drying process. Compared to g
or g
, WUE
was strongly correlated with g
/g
. WUE
improved within Ψ
range between -0.83 and -1.15 MPa. In summary, g
showed a higher sensitivity to drought than g
. Under moderate and severe drought at Ψ
≤ -1.01 MPa, furthermore from hydraulic signals, ABA was also involved in this co-ordination reductions of g
and g
and thereby regulated A
and WUE
.
To ameliorate the deficient output flow performance of the piezoelectric pumps with cantilever valves, a dual-inlet pump with a simple valves system is proposed. On the basis of explaining the ...structure design of the prototype, the working principle of the prototype is explained, and the output flow is theoretically analyzed. Then, the manufacturing process of the prototype is introduced. The general operating frequency of the pump was obtained by combining the finite element analysis of the piezoelectric actuator under dry and wet modes with the mechanical vibration test, and a series of measured flow rates were compared and improved through valve stiffness optimization and pump chamber height adjustment in the subsequent control experiment. The proposed piezoelectric pump achieves a maximum flow rate of 33.18 mL/min at a 180 Vp-p voltage with the driving frequency of 100 Hz, which may bring new inspiration for the application of small intelligent pumps in the field of microfluidics.
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