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Plant carbon (C) content is one of the most important plant traits and is critical to the assessment of global C cycle and ecological stoichiometry; however, the global variations in plant C content remain poorly understood. In this study, we conducted a global analysis of the plant C content by synthesizing data from 4318 species to document specific values and their variation of the C content across plant organs and life forms. Plant organ C contents ranged from 45.0 % in reproductive organs to 47.9 % in stems at global scales, which were significantly lower than the widely employed canonical value of 50 %. Plant C content in leaves (global mean of 46.9 %) was higher than that in roots (45.6 %). Across life forms, woody plants exhibited higher C content than herbaceous plants. Conifers, relative to broad-leaved woody species, had higher C content in roots, leaves, and stems. Plant C content tended to show a decrease with increasing latitude. The life form explained more variation of the C content than climate. Our findings suggest that specific C content values of different organs and life forms developed in our study should be incorporated into the estimations of regional and global vegetation biomass C stocks.

Researchers have made advances in reducing the metabolic rate of both walking and running by modulating mono-articular energy with exoskeletons. However, how to modulate multiarticular energy with exoskeletons to improve the energy economy of both walking and running is still a challenging problem, due to the lack of understanding of energy transfer among human lower-limb joints. Based on the study of the energy recycling and energy transfer function of biarticular muscles, we proposed a hip–knee unpowered exoskeleton that emulates and reinforces the function of the hamstrings and rectus femoris in different gait phases. The biarticular exo-tendon of the exoskeleton assists hamstrings to recycle the kinetic energy of the leg swing while providing hip extension torque in the swing phase. In the following stance phase, the exo-tendon releases the stored energy to assist the co-contraction of gluteus maximus and rectus femoris for both hip extension and knee extension, thus realizing the phased modulation of hip and knee joint energy. The metabolic rate of both walking (1.5 m/s) and running (2.5 m/s) can be reduced by 6.2% and 4.0% with the multiarticular energy modulation of a hip–knee unpowered exoskeleton, compared to that of walking and running without an exoskeleton. The bio-inspired design method of this study may inspire people to develop devices that assist multiple gaits in the future.

Suzhou is one of China’s model cities due to its economic development in recent decades. Although the city deserves recognition for its efforts in urban heritage conservation, the current preservation strategy only targets the ancient city and neglects the separation of the entire urban landscape. This has become a huge hidden problem in the process of Suzhou’s sustainable development. This study, based on this background, explores the development process of Suzhou and the problems in the current urban planning, and then proposes suggestions for optimization. The historic urban landscape approach provides a solution to this problem by analyzing the urban form and urban landscape features of Suzhou in three important historical periods: pre-1949, 1949–1978, and post-1978. This study discusses the development process of Suzhou and the problems in the current urban planning, and makes the following contributions: (1) the dichotomy between modernity and tradition in the urban landscape of Suzhou is shown from a morphological perspective, revealing that this dichotomy is based on rapid urbanization and the one-sided pursuit of economic development, (2) revisits the role of Suzhou traditional gardens in order to better integrate them as structural elements in urban planning, (3) proposes the intangible value of urban heritage and combined with the historic urban landscape of looking beyond the notion of the “historic center” or “ensemble” to help all Suzhou residents form a more coherent place attachment and local identity.

Neurogenesis, a highly orchestrated process, entails the transition from a pluripotent to neural state and involves neural progenitor cells (NPCs) and neuronal/glial subtypes. However, the precise epigenetic mechanisms underlying fate decision remain poorly understood. Here, we delete KDM6s (JMJD3 and/or UTX), the H3K27me3 demethylases, in human embryonic stem cells (hESCs) and show that their deletion does not impede NPC generation from hESCs. However, KDM6-deficient NPCs exhibit poor proliferation and a failure to differentiate into neurons and glia. Mechanistically, both JMJD3 and UTX are found to be enriched in gene loci essential for neural development in hNPCs, and KDM6 impairment leads to H3K27me3 accumulation and blockade of DNA accessibility at these genes. Interestingly, forced expression of neuron-specific chromatin remodelling BAF (nBAF) rescues the neuron/glia defect in KDM6-deficient NPCs despite H3K27me3 accumulation. Our findings uncover the differential requirement of KDM6s in specifying NPCs and neurons/glia and highlight the contribution of individual epigenetic regulators in fate decisions in a human development model. Neurogenesis is an ordered transition from pluriptotent cells to neural precursor cells (NPCs) to neurons. Here the authors show that loss of the lysine demethylases JMJD3 and UTX leads reduced DNA accessibility at neurogenesis loci in human NPCs, and that the chromatin remodeller BAF can rescue differentiation defects.

Background Walking and running are the most common means of locomotion in human daily life. People have made advances in developing separate exoskeletons to reduce the metabolic rate of walking or running. However, the combined requirements of overcoming the fundamental biomechanical differences between the two gaits and minimizing the metabolic penalty of the exoskeleton mass make it challenging to develop an exoskeleton that can reduce the metabolic energy during both gaits. Here we show that the metabolic energy of both walking and running can be reduced by regulating the metabolic energy of hip flexion during the common energy consumption period of the two gaits using an unpowered hip exoskeleton. Methods We analyzed the metabolic rates, muscle activities and spatiotemporal parameters of 9 healthy subjects (mean ± s.t.d; 24.9 ± 3.7 years, 66.9 ± 8.7 kg, 1.76 ± 0.05 m) walking on a treadmill at a speed of 1.5 m s −1 and running at a speed of 2.5 m s −1 with different spring stiffnesses. After obtaining the optimal spring stiffness, we recruited the participants to walk and run with the assistance from a spring with optimal stiffness at different speeds to demonstrate the generality of the proposed approach. Results We found that the common optimal exoskeleton spring stiffness for walking and running was 83 Nm Rad −1 , corresponding to 7.2% ± 1.2% (mean ± s.e.m, paired t-test p < 0.01) and 6.8% ± 1.0% (p < 0.01) metabolic reductions compared to walking and running without exoskeleton. The metabolic energy within the tested speed range can be reduced with the assistance except for low-speed walking (1.0 m s −1 ). Participants showed different changes in muscle activities with the assistance of the proposed exoskeleton. Conclusions This paper first demonstrates that the metabolic cost of walking and running can be reduced using an unpowered hip exoskeleton to regulate the metabolic energy of hip flexion. The design method based on analyzing the common energy consumption characteristics between gaits may inspire future exoskeletons that assist multiple gaits. The results of different changes in muscle activities provide new insight into human response to the same assistive principle for different gaits (walking and running).

Nucleoli are fundamentally essential sites for ribosome biogenesis in cells and formed by liquid-liquid phase separation (LLPS) for a multilayer condensate structure. How the nucleoli integrity is maintained remains poorly understood. Here, we reveal that METTL3/METTL14, the typical methyltransferase complex catalyzing N6-methyladnosine (m 6 A) on mRNAs maintain nucleoli integrity in human embryonic stem cells (hESCs). METTL3/METTL14 deficiency impairs nucleoli and leads to the complete loss of self-renewal in hESCs. We further show that SUV39H1/H2 protein, the methyltransferases catalyzing H3K9me3 were dramatically elevated in METTL3/METTL14 deficient cells, which causes an accumulation and infiltration of H3K9me3 across the whole nucleolus and impairs the LLPS. Mechanistically, METTL3/METTL14 complex serves as an essential adapter for CRL4 E3 ubiquitin ligase targeting SUV39H1/H2 for polyubiquitination and proteasomal degradation and therefore prevents H3K9me3 accumulation in nucleoli. Together, these findings uncover a previously unknown role of METTL3/METTL14 to maintain nucleoli integrity by facilitating SUV39H1/H2 degradation in human cells. Nucleoli are essential cellular sites for ribosome biogenesis that are formed by liquid-liquid phase separation. Here the authors show that METTL3/METTL14 maintain nucleoli integrity through mediating SUV39H1/2 degradation in human embryonic stem cells.

Background Hepatic organoids (HOs), validated through comparative sequencing with human liver tissues, are reliable models for liver research. Comprehensive transcriptomic and proteomic sequencing of HOs throughout their induction period will enhance the platform’s utility, aiding in the elucidation of liver development’s molecular mechanisms. Methods We developed hepatic organoids (HOs) from embryonic stem cells (ESCs) through a de novo induction protocol, mimicking the stages of fetal liver development: ESCs to definitive endoderm (DE), then to foregut (FG), hepatoblasts (HB), and finally to HOs stage 1 (HO1), culminating in self-organizing HOs stage 2 (HO2) via dissociation and re-inoculation. The successful establishment of HOs was validated by immunofluorescence staining and RT-qPCR for specific markers. Comprehensive transcriptomic and proteomic sequencing and analysis were conducted on FG, HB, HO1, and HO2. Results Our data suggest that several transcription factors (TFs) activated during the HB stage share overlapping target genes with the vitamin D receptor (VDR). Calcitriol, a direct activator of VDR, notably facilitated the FG to HB stage transition by activating VDR and enhancing key TFs, thereby promoting hepatic progenitor cell maturation. Furthermore, our findings revealed a significant transition towards glycolytic energy metabolism at the HO2 stage, characterized by increased glycolytic flux and reduced oxidative phosphorylation. Inhibition of glycolysis using 2-deoxy-D-glucose (2-DG) led to suppressed growth and differentiation at the HO2 stage. Analysis of signaling pathways indicated upregulation of the HIF-1 pathway, which is associated with glycolysis activation, as well as the MAPK and PI3K-AKT pathways, which regulate HIF-1α protein translation. Conclusions We elucidated a pivotal role for calcitriol in facilitating the transition from FG to HB by activating VDR and augmenting the expression of critical transcription factors (TFs). Besides, our research underscores a shift in metabolic pathways toward glycolytic energy metabolism in HO2 organoids. Overall, our multiomics approach reveals the intricate molecular regulation during the development of HOs. Graphical abstract

Although an Automatic Identification System (AIS) can be used to monitor trajectories, it has become a reality for remote sensing satellite clusters to monitor maritime moving targets. The increasing demand for monitoring poses challenges for the construction of satellites, the monitoring capabilities of which urgently need to be evaluated. Conventional evaluation methods focus on the spatial characteristics of monitoring; however, the temporal characteristics and the target’s kinematic characteristics are neglected. In this study, an evaluation method that integrates the spatial and temporal characteristics of monitoring along with the target’s kinematic characteristics is proposed. Firstly, a target motion prediction model for calculating the transfer probability and a satellite observation information calculation model for obtaining observation strips and time windows are established. Secondly, an index system is established, including the target detection capability, observation coverage capability, proportion of empty window, dispersion of observation window, and deviation of observation window. Thirdly, a comprehensive evaluation is completed through combining the analytic hierarchy process and entropy weight method to obtain the monitoring capability score. Finally, simulation experiments are conducted to evaluate the monitoring capabilities of satellites for ship trajectories. The results show that the method is effective when the grid size is between 1.6 and 1.8 times the target size and the task duration is approximately twice the time interval between trajectory points. Furthermore, the method is proven to be usable in various environments.

Rare earth elements (REEs) and yttrium (Y), together known as REY, are extremely enriched in deep-sea pelagic sediments, attracting much attention as a promising new REY resource. To understand the influence of hydrothermal processes on the enrichment of REY in deep-sea sediments from the eastern South Pacific Ocean, we conducted detailed lithological, bulk sediment geochemical, and in situ mineral geochemical analyses on gravity core sample S021GC17 from the Yupanqui Basin of eastern South Pacific. The REY-rich muds of S021GC17 are dark-brown to black zeolitic clays with REY contents (ΣREY) ranging from 1057 to 1882 ppm (average 1329 ppm). The REY-rich muds display heavy rare earth elements (HREE) enriched patterns, with obvious depletions in Ce, and positive anomalies of Eu in Post-Archean Australian Shale (PAAS)-normalized REE diagrams. In contrast, the muds of S021GC17 show light rare earth elements (LREE) enriched patterns and positive anomalies of Ce and Eu in the seawater-normalized REE diagrams. Total REY abundances in the core show positive correlations with CaO, P2O5, Fe2O3, and MnO concentrations. In situ analyses of trace element contents by laser ablation-inductively coupled plasma–mass spectrometry (LA-ICP-MS) demonstrate that bioapatite fossils contain high REY concentrations (998 to 22,497 ppm, average 9123 ppm), indicating that they are the primary carriers of REY. The in situ Nd isotope values of bioapatites are higher than the average values of seawater in Pacific Ocean. Fe–Mn micronodules are divided into hydrogenetic and diagenetic types, which have average REY concentrations of 1586 and 567 ppm, respectively. The high contents of Fe-Mn-Ba-Co-Mo, the positive correlations between ΣREY and Fe-Mn, the ratios of Fe/Ti and Al/(Al + Fe + Mn), and the LREE-enriched patterns in the REY-rich muds, combined with high Nd isotope values shown by bioapatite fossils, strongly indicate that the hydrothermal fluids have played an important role in the formation of the REY-rich sediments in the eastern South Pacific Ocean.

Social participation is an important tool in heritage conservation, but levels remain low in developing countries. To increase social-participation awareness of urban-heritage conservation, this study aimed to find an effective method to determine the factors that affect participation awareness, with a focus on the magnitude of each influence. Through literature analysis we developed hypotheses about the factors affecting participation awareness, and then developed a linear regression model. In order to test the reliability of the model, we selected Suzhou as the research object and obtained the following conclusions: (1) Suzhou’s social-participation awareness was positively correlated with place identity, urban memory, subjective cognition, objective knowledge, and place identity. (2) The factor that had the strongest impact on Suzhou’s place identity was public space, with residence time and community sentiment also influencing place identity. (3) The factors that influenced the urban memory of Suzhou were residence time, urban transformation, and urban events with the most influential factor being lifestyle transformation. (4) Urban-heritage conservation social-participation awareness was higher among Suzhou people living in the old city than in the new city.