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Considering the influence of the ionosphere, troposphere, and other systematic errors on double-differenced ambiguity resolution (AR), we present an optimal triple-frequency code-phase combination determination method driven by both the model and the real data. The new method makes full use of triple-frequency code measurements (especially the low-noise of the code on the B3 signal) to minimize the total noise level and achieve the largest AR success rate (model-driven) under different ionosphere residual situations (data-driven), thus speeding up the AR by directly rounding. With the triple-frequency Beidou Navigation Satellite System (BDS) data collected at five stations from a continuously-operating reference station network in Guangdong Province of China, different testing scenarios are defined (a medium baseline, whose distance is between 20 km and 50 km; a medium-long baseline, whose distance is between 50 km and 100 km; and a long baseline, whose distance is larger than 100 km). The efficiency of the optimal code-phase combination on the AR success rate was compared with that of the geometry-free and ionosphere-free (GIF) combination and the Hatch-Melbourne-Wübbena (HMW) combination. Results show that the optimal combinations can always achieve better results than the HMW combination with B2 and B3 signals, especially when the satellite elevation angle is larger than 45°. For the wide-lane AR which aims to obtain decimeter-level kinematic positioning service, the standard deviation (STD) of ambiguity residuals for the suboptimal combination are only about 0.2 cycles, and the AR success rate by directly rounding can be up to 99%. Compared with the HMW combinations using B1 and B2 signals and using B1 and B3 signals, the suboptimal combination achieves the best results in all baselines, with an overall improvement of about 40% and 20%, respectively. Additionally, the STD difference between the optimal and the GIF code-phase combinations decreases as the baseline length increases. This indicates that the GIF combination is more suitable for long baselines. The proposed optimal code-phase combination determination method can be applied to other multi-frequency global navigation satellite systems, such as new-generation BDS, Galileo, and modernized GPS.

The European Global Navigation Satellite System Galileo is gradually deploying its constellation. In order to provide reliable navigation and position services, the effectiveness and reliability of ambiguity resolution between reference stations is necessary in network real-time kinematic (NRTK). The multifrequency signal of Galileo could much enhance the ambiguity resolution (AR) reliability and robustness. In this study, to exploit full advantage of this, the geometry-free (GF) TCAR and ionospheric-free (IF) triple-carrier ambiguity resolution (TCAR) methods were utilized in solving the ambiguity in the Hong Kong area, which is an ionosphere disturbance active area, and compared with each other. The IF TCAR method was then used to combine multi-systems to improve Galileo E1 AR performance, which is named as the combined IF (CIF) TCAR method. Three experiments were carried out in the Hong Kong area and the results showed that the Galileo-only system could fix ambiguities on all satellite pairs correctly and reliably by the IF TCAR method, while the GF TCAR method showed a weaker performance. The wide-lane (WL) convergence time of the IF TCAR method is improved by about 37.6%. The IF TCAR method with respect to the GF TCAR method could improve the WL accuracy by 21.6% and the E1 accuracy by 72.7%, respectively. Compared with GPS-only TCAR or Galileo-only TCAR, the ambiguity accuracy and the convergence time of the CIF TCAR method, which combines GPS and Galileo, could be improved by about 25.7% and 47.1%, respectively.

The network real-time differential positioning technique is a good choice for meter and sub-meter level’s navigation. More attention has been paid to the Global Positioning System (GPS) and GPS + GLONASS (GLObal NAvigation Satellite System) network real-time differential positioning, but less on the GPS + BDS (BeiDou Navigation Satellite System) combination. This paper focuses on the GPS + BDS network real-time differential positioning. Since the noise of pseudorange observation is large, carrier-phase-smoothed pseudorange is usually used in the network real-time differential positioning to improve the positioning accuracy, while it will be interrupted once the satellite signal is lost or a cycle slip occurs. An improved algorithm in the position domain based on position variation information is proposed. The improved method is immune to the smoothing window and only depends on the number of available satellites. The performance of the network real-time differential positioning using the improved method is evaluated. The performance of GPS + BDS combination is compared with GPS-only solution as well. The results show that the positioning accuracy can be increased by around 10%–40% using the improved method compared with the traditional one. The improved method is less affected by the satellite constellation. The positioning accuracy of GPS + BDS solution is better than that of GPS-only solution, and can reach up to 0.217 m, 0.159 m and 0.330 m in the north, east and up components for the static user station, and 0.122 m, 0.133 m and 0.432 m for the dynamic user station. The positioning accuracy variation does not only depend on whether the user is inside or outside the network, but also on the position relation between the user and network.

Elodea nuttallii is widely used in Chinese mitten crab (CMC) rearing practice, but it is not a native aquatic plant and cannot endure high temperature. Thus, large E. nuttallii mortality and water deterioration events could occur during high-temperature seasons. The aim of this study was to identify the use of local macrophytes in CMC rearing practice, including Ipomoea aquatic and Oryza sativa . A completely randomized field experiment was conducted to investigate the crab yield, water quality, bacterioplankton community and functions in the three different systems ( E. nuttallii , I. aquatic , and O. sativa ). Average crab yields in the different macrophyte systems did not differ significantly. The I. aquatic and O. sativa systems significantly decreased the total nitrogen and nitrate-N quantities in the outflow waters during the rearing period compared to the E. nuttallii system, and the I. aquatic and O. sativa plants assimilated more nitrogen than the E. nuttallii plant. Moreover, the significant changes of bacterioplankton abundances and biodiversity in the three systems implied that cleanliness of rearing waters was concomitantly attributed to the differential microbial community and functions. In addition, principle component analysis successfully differentiated the bacterioplankton communities of the three macrophytes systems. Environmental factor fitting and the co-occurrence network analyses indicated that pH was the driver of bacterioplankton community structure. Functional predictions using PICRUSt (v.1.1.3) software based on evolutionary modeling indicated a higher potential for microbial denitrification in the I. aquatic and O. sativa systems. Notably, the O. sativa plants stopped growing in the middle of the rearing period. Thus, the I. aquatic system rather than the O. sativa system could be a feasible and environmental-friendly alternative to the E. nuttallii system in CMC rearing practice.

为探讨添加生物质炭条件下羊粪堆肥的腐殖化特征，采用静态堆制、高温好氧发酵的方法设置了3个处理，以羊粪与食用菌渣鲜质量比9∶1混合体作为初级物料，在初级物料上分别添加450、650℃热解的稻壳生物质炭（占初级物料干质量百分比15%，BC450、BC650）以及未炭化的稻壳（与生物质炭等体积，CK），进行43 d的堆肥试验，监测了堆肥体水溶性有机物、总有机碳、可提取腐植酸含量等，分析了堆肥体腐殖化率、胡富比等。结果表明，与CK处理相比，添加生物质炭促进了羊粪与食用菌渣混合堆肥体的无害化及腐熟，其中BC650处理对堆肥腐解的促进作用优于BC450处理，但两者间无显著差异（P>0.05）；堆肥过程中BC450、BC650处理较CK处理减少了水溶性有机物、可提取腐植酸、富里酸、胡敏酸含量，降低了堆肥腐殖化率、腐殖化指数，提高了总有机碳、胡敏素含量，提升了胡富比，堆肥43 d后，BC450、BC650处理的可提取腐植酸含量比CK处理分别降低了29.32%、42.37%，富里酸含量分别降低了38.05%、46.77%，胡敏酸含量分别降低了26.28%、40.83%，但BC450、BC650处理之间均无显著差异（P>0.05）。综合堆温、种子发芽指数、腐植酸及其组成等腐殖化特征来看，添加生物质炭促进了堆肥的腐解，虽没有提升腐植酸及其组分的绝对含量，但提高了腐植酸的稳定度，且450℃热解的稻壳生物质炭堆肥腐殖化程度优于650℃热解生物质炭。To investigate the humification characteristics of sheep manure compost following the addition of biochar, static stacking and high temperature aerobic fermentation was adopted. The three treatments involved mixtures of sheep dung and edible fungus residue with a fresh-weight ratio of 9:1 as the primary material. Rice husk biochar pyrolysis at 450℃ and 650℃(15% dry weight of the primary material) was

Effects of fertilisation and other management techniques on a weed community were evaluated during wheat growth in a rice-wheat cropping system. Fertiliser treatments were C0 (C means chemical, C0 means zero chemical fertiliser.), CN (N fertiliser), CNK (N plus K fertiliser), CNPK (N plus P and K fertiliser), CNP (N plus P fertiliser), and CPK (P plus K fertiliser). Weed density, biomass, and bio-diversity were determined. Redundancy analysis (RDA) was used to investigate the relationship between fertiliser management, weed species, and weed density. The overall weed densities in the C0 and CPK treatments were the greatest during wheat seeding and ripening periods and were significantly greater than densities in the other treatments. N, P and organic matter in soil were highly correlated with weed species and density, whereas K in soil was not significantly correlated with weed species and weed density. N fertiliser significantly reduced weed density. Balanced fertilisation maintained weed species richness and resulting in a high yield of wheat. CNPK application reduced weed damage and improved the productivity and stability of the farmland ecosystem.

Developing modern circular agriculture is one of the important ways to promote agricultural sustainable development, facilitating the achievement of the Sustainable Development Goals adopted by the United Nations. However, when agricultural production operators constructed particular systems, they often lacked accurate data support and parameter matching. Consequently, problems such as unknown input and output, low circulation efficiency, and lack of comprehensive evaluation occurred, increasing challenges for efficient circulation of the systems. Therefore, based on sufficient data collection and field investigation, this research integrated emergy analysis and life cycle assessment to conduct sustainability evaluation on the modern Straw–Sheep–Cropland agro-pastoral circular system. Then the system was optimized by means of coupling parameter adjustment and key technology regulation. The results showed that the whole system required lower total emergy input after optimization. And the total weighted value of potential environmental impacts of the optimized system was 47.12% of that of the original system. Meanwhile, annual environmental service emergy in air, water, and soil was reduced significantly compared with the original one. In general, the optimized system had good performance in reduction, reuse, and controllability, so its sustainability was also high. This research formed a systematic method suitable for evaluating and optimizing the modern agro-pastoral circular system, which provided accurate guidance for the scientific construction and sustainable development of circular agriculture systems.

Purpose Although micronutrients are essential to higher plants, it remains unclear whether the projected future climate change would affect their availability to plants. The objective of this study was to investigate the effect of carbon dioxide (CO 2 ) enrichment and warming on soil micronutrient availability and plant uptake. Materials and methods This study was conducted in an open field experiment with CO 2 enrichment and plant canopy warming. Four treatments were included: (1) free-air CO 2 enrichment up to 500 ppm (CE); (2) canopy warming by plus 2 °C (WA); (3) CO 2 enrichment combined with canopy warming (CW), and (4) ambient condition as control. Plant and soil samples were collected, respectively, at the jointing, heading, and ripening stage over the whole wheat growing season in 2014. The micronutrient concentrations both in soil and plant were both analyzed, and the accumulated uptake by wheat harvest was assessed. Results and discussion Both CO 2 enrichment and warming increased the availability of most soil micronutrients. The availability of Fe, Mn, Cu, and Zn under CO 2 enrichment increased by 47.7, 22.5, 59.8, and 114.1 %, respectively. Warming increased the availability of Fe, Cu, and Zn by 60.4, 23.8, and 15.3 %, respectively. The plant growth induced changes in soil pH and in soil microbial biomass carbon (MBC) accounted to the changes in soil micronutrient availability. The enrichment of CO 2 and warming had significant effects on micronutrient uptake by wheat. The enrichment of CO 2 decreased the concentration of Fe by 9.3 %, while it increased the concentrations of Mn and Zn by 18.9 and 8.1 % in plant shoot, respectively. Warming increased the concentration of Fe and Cu by 24.3 and 7.6 % in plant shoot, respectively. The increase in soil micronutrient availability did not always lead to the increase in micronutrient uptake. The element types and crop growth stage affected the uptake of micronutrients by wheat under CO 2 enrichment and warming. Additionally, CO 2 enrichment decreased the translocation of Fe and Zn by 25.3 and 10.0 %, respectively, while warming increased the translocation of Fe, Mn, Cu, and Zn across stages. Conclusions Our results demonstrated that CO 2 enrichment and warming would improve availability of some micronutrients and their uptake by wheat. However, it is still unclear whether a net removal of micronutrient through crop straw harvest would occur under CO 2 enrichment and warming.

High-efficiency blue phosphorescence emission is essential for organic optoelectronic applications. However, synthesizing heavy-atom-free organic systems having high triplet energy levels and suppressed non-radiative transitions—key requirements for efficient blue phosphorescence—has proved difficult. Here we demonstrate a simple chemical strategy for achieving high-performance blue phosphors, based on confining isolated chromophores in ionic crystals. Formation of high-density ionic bonds between the cations of ionic crystals and the carboxylic acid groups of the chromophores leads to a segregated molecular arrangement with negligible inter-chromophore interactions. We show that tunable phosphorescence from blue to deep blue with a maximum phosphorescence efficiency of 96.5% can be achieved by varying the charged chromophores and their counterions. Moreover, these phosphorescent materials enable rapid, high-throughput data encryption, fingerprint identification and afterglow display. This work will facilitate the design of high-efficiency blue organic phosphors and extend the domain of organic phosphorescence to new applications. A strategy to confine phosphorescent organic chromophores within ionic crystals proves effective in suppressing non-radiative recombination channels and increasing the phosphorescence efficiency of blue-emitting heavy-atom-free emitters.

RNA methylation plays crucial roles in gene expression and has been indicated to be involved in tumorigenesis, while it is still unclear whether m1A modifications have potential roles in the prognosis of hepatocellular carcinoma (HCC). In this study, we comprehensively analyzed RNA sequencing (RNA-seq) data and clinical information using The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. We collected 10 m1A regulators and performed consensus clustering to determine m1A modification patterns in HCC. The CIBERSORT method was utilized to evaluate the level of immune cell infiltration. Principal component analysis was used to construct the m1A-score model. In the TCGA-LIHC cohort, the expression of all 10 m1A regulators was higher in tumor tissues than in normal control tissues, and 8 of 10 genes were closely related to the prognosis of HCC patients. Two distinct m1A methylation modification patterns (Clusters C1 and C2) were identified by the 10 regulators and were associated with different overall survival, TNM stage and tumor microenvironment (TME) characteristics. Based on the differentially expressed genes (DEGs) between C1 and C2, we identified three gene clusters (Clusters A, B and C). C1 with a better prognosis was mainly distributed in Cluster C, while Cluster A contained the fewest samples of C1. An m1A-score model was constructed using five m1A regulators related to prognosis. Patients with higher m1A scores showed a poorer prognosis than those with lower scores in the TCGA-LIHC and GSE14520 datasets. In conclusions, our study showed the vital role of m1A modification in the TME and progression of HCC. Quantitative evaluation of the m1A modification patterns of individual patients facilitates the development of more effective biomarkers for predicting the prognosis of patients with HCC.