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Introduction: With the aggravation of aging and the growing number of stroke patients suffering from hemiplegia in China, rehabilitation robots have become an integral part of rehabilitation training. However, traditional rehabilitation robots cannot modify the training parameters adaptively to match the upper limbs’ rehabilitation status automatically and apply them in rehabilitation training effectively, which will improve the efficacy of rehabilitation training.Methods: In this study, a two-degree-of-freedom flexible drive joint rehabilitation robot platform was built. The forgetting factor recursive least squares method (FFRLS) was utilized to estimate the impedance parameters of human upper limb end. A reward function was established to select the optimal stiffness parameters of the rehabilitation robot.Results: The results confirmed the effectiveness of the adaptive impedance control strategy. The findings of the adaptive impedance control studies showed that the adaptive impedance control had a significantly greater reward than the constant impedance control, which was in line with the simulation results of the variable impedance control. Moreover, it was observed that the levels of robot assistance could be suitably modified based on the subject’s different participation.Discussion: The results facilitated stroke patients’ upper limb rehabilitation by enabling the rehabilitation robot to adaptively change the impedance parameters according to the functional status of the affected limb. In clinic therapy, the proposed control strategy may help to adjust the reward function for different patients to improve the rehabilitation efficacy eventually.

Although abundant transmission polarization conversion metasurfaces (T-PCMs) have been reported, a dual-band T-PCM has only received little attention. Moreover, a reconfigurable-phase design of the T-PCMs is limited to a single-frequency band operation. There is hardly any literature to integrate dual-band and reconfigurable-phase features into a T-PCM. Herein, a dual-band T-PCM is presented based on the Fabry-Pérot-like resonant cavity. Particularly, the T-PCM meta-atom contains dual anisotropic patches distributed in different layers, and the novel dual-patch structure introduces multiple current modes to implement dual-band operation. Further, a reconfigurable-phase design of the dual-band meta-atom is performed, and four PIN diodes are embedded in each meta-atom to realize a 1-bit reconfigurable phase. In this way, the T-PCM meta-atom can simultaneously achieve high-efficiency 90° polarization rotation and 1-bit dynamic phase manipulation in 2.3–3.0 GHz and 4.4–7.5 GHz. By changing the encoding of the T-PCM, both cross-polarized transmission and beam manipulation are demonstrated in two divided bands. A sample is fabricated and measured to validate our design, and the results confirm the simulations. With the advantages of ingenious design and a clear operation mechanism, the novel dual-patch structure can be extended to the terahertz and optics regimes.

Recurrent complete atrioventricular block induced by coronary spasm is rare. We present a case of a 47-year-old woman who suffered from two episodes of out-of-hospital cardiac arrest within one year due to complete atrioventricular block caused by coronary vasospasm. No implantable cardioverter defibrillator was implanted after her first episode. As for the second episode, permanent brain injury was left behind despite successful cardiopulmonary resuscitation. She underwent a challenging rehabilitation process and an implantable cardioverter defibrillator was implanted before discharge. We captured the dynamic changes of the electrocardiogram during the episode with high temporal resolution. This case illustrates the importance of recognizing coronary spasm as a potential cause of complete atrioventricular block and highlights the need for implantable cardioverter defibrillator in such patients to improve survival and quality of life.

Biochar amendment to soils is regarded as the potential practice to mitigate climate change while also increasing yields. However, geographical differences in the effects of biochar on cereal production and greenhouse gas emissions are not well understood at the global scale. Random forest, a classic machine learning algorithm, was employed to reveal the drivers of geographical differences in the effects of biochar on cereals yield and greenhouse gas emissions. The potential for yield increases and greenhouse gas emission reduction was predicted in this study. The results indicate that nitrogen fertilizer rate is the most important factor determining the impact of biochar on cereal yield, while biochar application rate strongly affected greenhouse gas emissions. Globally, the maximum increase in cereal crop yields under biochar application was 14.1%. To achieve the largest increment globally, recommended values of biochar application, mineral nitrogen application rate and pyrolysis temperature were predicted to be around 36.3 t ha−1, 193.7 kg N ha−1 and 420 °C, respectively. The maximum reductions of methane and nitrous oxide emissions from paddy fields around the world were 21.6% and 31.0%, and from maize and wheat fields 35.7% and 36.1%, respectively. Although biochar can potentially improve yields while reducing greenhouse gas emissions worldwide under proper management, the performance of biochar showed great heterogeneity.

Geochemical survey data analysis is recognized as an implemented and feasible way for lithological mapping to assist mineral exploration. With respect to available approaches, recent methodological advances have focused on deep learning algorithms which provide access to learn and extract information directly from geochemical survey data through multi-level networks and outputting end-to-end classification. Accordingly, this study developed a lithological mapping framework with the joint application of a convolutional neural network (CNN) and a long short-term memory (LSTM). The CNN-LSTM model is dominant in correlation extraction from CNN layers and coupling interaction learning from LSTM layers. This hybrid approach was demonstrated by mapping leucogranites in the Himalayan orogen based on stream sediment geochemical survey data, where the targeted leucogranite was expected to be potential resources of rare metals such as Li, Be, and W mineralization. Three comparative case studies were carried out from both visual and quantitative perspectives to illustrate the superiority of the proposed model. A guided spatial distribution map of leucogranites in the Himalayan orogen, divided into high-, moderate-, and low-potential areas, was delineated by the success rate curve, which further improves the efficiency for identifying unmapped leucogranites through geological mapping. In light of these results, this study provides an alternative solution for lithologic mapping using geochemical survey data at a regional scale and reduces the risk for decision making associated with mineral exploration.

3D seismic data recently acquired from the Ordos Basin shows three sets of regularly distributed fault systems, which overrides previous understanding that no faults were developed in this basin. Seismic interpretation suggests that the faults in the southwestern Ordos Basin have three basic characteristics, namely extreme micro-scale, distinct vertical stratification, and regularity of planar distribution. These NS-, NW-, and NE-trending fault systems developed in the Meso-Neoproterozoic – Lower Ordovician strata. Of these, the NS-trending fault system mainly consists of consequent and antithetic faults which show clear syndepositional deformation. The fault systems in the Carboniferous – Middle-Lower Triassic strata are not clear on seismic reflection profiles. The NW- and NE-trending fault systems are developed in the Upper Triassic – Middle Jurassic strata. Of these, the NW-trending fault system appears as a negative flower structure in sectional view and in an en echelon pattern in plan-view; they show transtensional deformation. A NE-trending fault system that developed in the Lower Cretaceous – Cenozoic strata shows a Y-shaped structural style and tension-shear properties. A comprehensive analysis of the regional stress fields at different geologic times is essential to determine the development, distribution direction, and intensity of the activity of fault systems in the Ordos Basin. Current exploration suggests three aspects in which the faults within the Ordos Basin are crucial to oil and gas accumulation. Firstly, these faults serve as vertical barriers that cause the formation of two sets of relatively independent petroleum systems in the Paleozoic and Mesozoic strata respectively; this is the basis for the ‘upper oil and lower gas’ distribution pattern. Secondly, the vertical communication of these faults is favorable for oil and gas migration, thus contributing to the typical characteristics of multiple oil and gas fields within the basin, i.e. oil and gas reservoirs with multiple superimposed strata. Finally, these faults and their associated fractures improve the permeability of Mesozoic tight reservoirs, providing favorable conditions for oil enrichment in areas around the fault systems.

The intensifying exploration for deep-buried oil and gas reserves in the southwestern Tarim Basin accelerates the necessity to understand how the structure and evolution of the Precambrian basement affect the development and distribution of Precambrian strata. However, the lack of systematic and comprehensive understanding of the structural characteristics of the Precambrian basement in the southwestern Tarim Basin restricts further advancements in the exploration of ultra-deep oil and gas reserves in this area. Based on the previous research results, this study analyzed the lithology, age, structure, and evolution of the Precambrian basement in the southwestern Tarim Basin by utilizing integrated research methods of geology and geophysics and in combination with the U-Pb dating results of the Precambrian basement. The results reveal that the structure of the Precambrian basement in the Bachu uplift region is characterized by Paleozoic strata overlying directly on the Paleo-proterozoic metamorphic rocks/granites. In the Maigaiti slope and southwestern depression, it exhibits a typical three-tier structure: the Paleoproterozoic metamorphic rocks/granites at the bottom, overlain by sedimentary build-ups from the rifting to depression evolution of the Nanhua-Sinian system. Evolution of the Precambrian basement in the southwestern Tarim Basin was primarily transpired in five phases: continental rifting in the Columbia supercontinent (> 1.1 Ga), assembly of the southwestern Tarim block and the Australian plate (about 1.0 Ga), assemblage between the northern and southern Tarim blocks (900-800 Ma), Nanhua rifting period (760-640 Ma), and Sinian depression period (< 635 Ma). The uplift and downwarping structures during the Nanhua rifting period dictated the development of the Sinian-Lower Cambrian sedimentary strata. In-depth research into the structure and evolution of the Precambrian basement in the southwestern Tarim Basin, as presented in this study, provides important theoretical basis for deep oil and gas exploration in the region, and helps to promote further development of ultra-deep oil and gas exploration.