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To further study the effect of different crop rotation patterns on the productivity of oilseed flax. In this study, the “Jinya No. 10” flax cultivar was used as the object, and a DSSAT model was constructed using 2017-2018 data to simulate the field trials (4-year rotation cycle) during the 30 years from 1994. The experiments were designed with six different crop rotation patterns including the following: flax→flax→flax→flax[(F)FFF], flax→wheat→maize→flax[(F)WMF], flax→maize→flax→wheat[(F)MFW], flax→flax→wheat→maize[(F)FWM], flax→wheat→flax→maize [(F)WFM], flax→wheat→maize→wheat[(F)WMW]. We investigated the effects of crop stubble, planting frequency of oilseed flax, years between plantings of oilseed flax, and years of continuous cropping on grain yield, aboveground biomass, and water use efficiency (WUE) in a semi-arid agricultural area. The results of the study showed that: (1) In the model calibration and validation, the RMSE of yield was 213.67 kg ha−1−217.43 kg ha−1, the RRMSE was 9.76%-10.79%; the RMSE of aboveground biomass was 796.24 kg ha−1−1527.81kg ha−1, the RRMSE was 13.46%-22.71%. The growing period of the cultivar was 95-97 d, indicating that the DSSAT model can simulate the productivity index of oilseed flax well. (2) Oilseed flax yield rotation than continuous mode significantly increased, the increase in 53.43%-54.28%, wheat, and maize stubble both significantly increased oilseed flax yield, compared with oilseed flax stubble increased by 31.04%, 31.95%. 25% oilseed flax frequency and 50% oilseed flax frequency than 100% oilseed flax planting frequency was significantly increased by 54.28% and 53.79%. The increase in grain yield of oilseed flax in the planting interval years was shown as 2a (32.97%) > 3a (31.51%) > 1a (30.84%). (3) The aboveground biomass of oilseed flax in the crop rotation compared to the continuous cropping pattern had a significant increase in the increase ranged from 60.49% to 100.31%. Wheat and maize stubble significantly increased the aboveground biomass of oilseed flax, compared with oilseed flax stubble increased by 25.67% and 22.56%. 25% oilseed flax frequency and 50% oilseed flax frequency than 100% oilseed flax planting frequency significantly increased by 92.02% and 72.81%. Oilseed flax aboveground biomass production in the planting intervals between the years of the increase in the performance of the 3a (39.8%) > 2a (28.99%) > 1a (19.45%). (4) The WUE of rotation compared to the continuous cropping mode increased between 45.78% and 58.54% for flax. The presence of wheat and maize stubble significantly increased the WUE of oilseed flax, compared to stubble of oilseed flax, which increased by 29.32% and 32.41%. 25% flax frequency and 50% flax frequency than 100% oilseed flax planting frequency significantly increased by 45.77% and 59.73%. Compared to the interval year 0a, the specific increase in WUE showed 2a (33.03%) > 1a (31.37%) > 3a (26.06%). Therefore, the continuous cultivation of oilseed flax will reduce productivity, should choose to rotate farming methods, replace different stubble, reduce the frequency of oilseed flax planting, and extend the interval between years of oilseed flax planting, and flax→wheat→maize→wheat is a suitable crop rotation mode in the northwestern dry zone.

Aiming at the problem of poor control effect of grid-side converter of doubly-fed induction generator due to load change and filter parameter perturbation, a double closed-loop control strategy of grid-side converter based on extended state observer (ESO) and sliding mode control is proposed. The inner loop adopts ESO-based sliding mode direct power control with power as the state variable, and the outer loop adopts ESO-based sliding mode control with voltage square as the state variable. Using ESO to estimate the system state variables and lumped uncertainties including unmodeled dynamics, load variation and filter parameter perturbation of the system, the sliding mode control method can be designed without the accurate mathematical model of the system to realize the robust control of grid-side converter in a complex environment. In addition, the power difference feedforward link is introduced to reduce the impact of the nonlinearity of the outer loop sliding mode control when the load changes. Finally, two examples of load charge and filter parameter perturbation are simulated, and the results show that the proposed control strategy has stronger robustness in the complex environment than traditional vector control and sliding mode control.

Quaternary volcanoes from the southeastern Tibetan Plateau occur at the Tengchong volcanic field (TVF). The Daliuchong volcano is the largest volcano in the TVF, which has the most felsic compositions with explosive eruptions. The eruption history and origin of the Daliuchong volcano are a matter of debate. In the present paper, we report the groundmass K-Ar ages, whole-rock Sr-Nd-Pb-Hf isotopes, zircon U-Pb ages, and Hf-O isotopic compositions for the Daliuchong volcano to constrain its eruption history and petrogenesis. The groundmass K-Ar ages and zircon U-Pb ages indicate mid-Pleistocene (0.6 Ma to 0.3 Ma) eruptions. The presence of zircon phenocrysts with enriched mantle-like O-Hf isotopes (δ18O < 6‰, and εHf about −2) suggests the involvement of mantle-derived basaltic magmas. The whole-rock Pb isotope compositions and Sr-Nd isotope modeling reveal the involvement of magma from the lower crust. The zircon xenocrysts reveal previously unrecognized 20-Ma magmatic activity at the TVF and contamination of late Cretaceous (66–80 Ma) S-type granites during the formation of the Daliuchong dacites. The dacite magma at Daliuchong was formed by mixing of the mantle-derived magma and lower-crust-derived magma and subsequently contaminated by upper crustal materials, including late Cretaceous S-type granitic rocks. [ABSTRACT FROM AUTHOR]

The Abaga basalts, which erupted within an intraplate background in the late Cenozoic, are situated in eastern central Inner Mongolia. Previous studies have explored the genesis of these basalts, which were influenced by the subduction of slab. Although trace element ratios demonstrate that altered oceanic crust (AOC) and sediments have contributed to the genesis of the basalts, limited information about the detailed percentages of mixing among sediments, AOC, and depleted mantle (DM) based on Sr‒Nd‒Pb isotopic values has been reported. In this study, we modelled the possible mixing percentages among AOC, DM, and sediments. The calculated results illustrate that a proportion of 80% DM, 16% AOC, and 4% sediments is appropriate for interpreting the Sr‒Nd‒Pb isotopic variation of the basalts. In addition, the associated major and trace elements of olivine and the partition coefficient of V between olivine and melt are used to estimate the crystallization temperatures of the olivine phenocrysts and oxygen fugacity of the basalts. The calculated results display that the olivine mainly crystallized between 1248 and 1293°C (standard error estimate: 51°C), and the fO2 values of the Abaga basalts range from FMQ + 0.14 to FMQ + 1.46 (FMQ, fayalite–magnetite–quartz buffer). The estimated oxygen fugacity values plot in the range of island arc basalts (from FMQ to FMQ + 2) but are higher than those of both mid-ocean ridge basalt (MORB) (from FMQ-0.4 to FMQ + 0.5) and Abaga xenoliths (from FMQ-1.55 to FMQ + 0.53), which indicates that the basaltic melts were more oxidized than those of MORB and the Abaga lithospheric mantle. Furthermore, the primary magma and the corresponding mantle source were more oxidized than MORB. The Ba/Th and Ce/Pb ratios of the basalt present positive correlations with fO2 values, demonstrating that the addition of sediments and oceanic crust into the mantle source may have contributed to increasing the fO2 values of the basalts. [ABSTRACT FROM AUTHOR]

The structure of the sidechain crosslinked Tyr‐Leu‐Trp peptide produced by the biarylitide crosslinking cytochrome P450Blt from Micromonospora sp. MW‐13 has been reanalysed by a series of NMR, computational and isotope labelling experiments and shown to contain a C−N rather than a C−O bond. Additional in vivo experiments using such a modified peptide show there is a general tolerance of biarylitide crosslinking P450 enzymes for histidine to tryptophan mutations within their minimal peptide substrate sequences despite the lack of such residues noted in natural biarylitide gene clusters. This work further highlights the impressive ability of P450s from biarylitide biosynthesis pathways to act as biocatalysts for the formation of a range of sidechain crosslinked tripeptides. [ABSTRACT FROM AUTHOR]

The structure of the sidechain crosslinked Tyr‐Leu‐Trp peptide produced by the biarylitide crosslinking cytochrome P450Blt from Micromonospora sp. MW‐13 has been reanalysed by a series of NMR, computational and isotope labelling experiments and shown to contain a C−N rather than a C−O bond. Additional in vivo experiments using such a modified peptide show there is a general tolerance of biarylitide crosslinking P450 enzymes for histidine to tryptophan mutations within their minimal peptide substrate sequences despite the lack of such residues noted in natural biarylitide gene clusters. This work further highlights the impressive ability of P450s from biarylitide biosynthesis pathways to act as biocatalysts for the formation of a range of sidechain crosslinked tripeptides. [ABSTRACT FROM AUTHOR]

We obtain new images of the 3D resistivity structure of the Wudalianchi volcanic field (WVF). No low‐resistivity structure is found beneath Laoheishan and Huoshaoshan volcanoes in the WVF, which challenges the hypothesis of one or more magma reservoirs in the upper crust of this region. We observe a low‐resistivity body beneath Weishan volcano; however, estimated magma emplacement rates conflict with the observed volume of that body. Due to the relatively low geothermal gradient and surface heat flow in the area, magma would cool rapidly and could not be sustained for a long time unless new magma was regularly introduced into the system, but our observations do not support this scenario. We suggest that the magma in the WVF mainly originates from the mantle or the base of the crust with little crustal residence, and that the low‐resistivity body in the upper crust is likely due to saline aqueous free fluids. Plain Language Summary: The origin of magma, whether it is derived directly from the deep mantle or has previously resided in the crust, plays a crucial role in determining volcanic eruption mechanisms. The presence of a magma reservoir in the shallow crust often signifies an increased risk of volcanic eruptions. The Wudalianchi volcanic field (WVF) is situated in northeastern China. Earlier research suggested the existence of a magma reservoir beneath the Weishan volcano within the WVF. However, our study reveals an absence of magma reservoirs beneath the more recently erupted Laoheishan and Huoshaoshan volcanoes. This raises the question of why a magma reservoir is present beneath Weishan, which experienced an eruption 0.5 Ma ago, rather than beneath Laoheshan and Huoshaoshan, which erupted a mere 300 years ago. Furthermore, the WVF is characterized by an extremely low geothermal gradient, causing magma in the shallow crust to lose substantial heat and cool rapidly, unless replenished by a continuous influx of high‐temperature magma. Nevertheless, the volume of magma injection inferred from the low‐resistivity body beneath Weishan is inconsistent with numerical simulation results. Consequently, we suggest that the low‐resistivity body beneath Weishan volcano is instead a structure containing saline aqueous free fluids, not magma. Key Points: Electrical structure of the Wudalianchi volcanic field (WVF) is imagedSubsurface beneath Laoheishan and Huoshaoshan volcanoes is highly resistiveLow‐resistivity body beneath Weishan volcano is due to saline aqueous free fluids [ABSTRACT FROM AUTHOR]