Seedling dynamics differ between canopy species and understory species in a tropical seasonal rainforest, SW China.

We used 11 years of census data from 450 seedling quadrats established in a 20-ha forest dynamics plot to study seedling dynamics in tree species of a tropical seasonal rainforest in Xishuangbanna, southwestern China. We found that overall seedling recruitment rate and relative growth rate were higher in the rainy season than in the dry season. Both the recruitment rate of seedlings from canopy tree species (two species) and the relative growth rate of seedlings from understory species (nine species) were higher in the rainy season than in the dry season. However, in the rainy season, the recruitment rate of seedlings was higher for canopy tree species than for understory tree species. In addition, relative growth rate of seedlings was higher in the canopy species than in understory seedlings in the dry season. We also observed that, in both rainy and dry seasons, mortality rate of seedlings was higher for canopy species than for understory species. Overall, canopy tree species appear to have evolved a flexible strategy to adapt to the seasonal changes of a monsoon climate. In contrast, understory tree species seem to have adopted a conservative strategy. Specifically, these species mainly release seedlings in the rainy season and maintain relatively stable populations with a lower mortality rate and recruitment rate in both dry and rainy seasons. Our study suggests that canopy and understory seedling populations growing in forest understory may respond to future climate change scenarios with distinct regeneration strategies.

Drought tolerance and species abundance mediate dry season negative density dependence in a tropical forest.

Conspecific negative density dependence (CNDD) is thought to be a key process in maintaining plant diversity. However, the strength of CNDD is highly variable in space and time as well as among species, and correlates of this variation that might help to understand and explain it remain largely unquantified. Using Bayesian hierarchical models, we took advantage of 10-year seedling monitoring data that were collected annually in every dry and rainy season in a seasonal tropical forest. We quantified the interspecific variation in the strength of CNDD and its temporal variation. We also examined potential correlates of this interspecific and temporal variation, including species functional traits (such as drought-tolerant traits, defense-related traits, and recourse acquisition traits) and species abundances. In the dry season, we found a negative relationship between the density of neighboring conspecific seedlings on seedling survival, while in the rainy season, there was a negative relationship between the density of neighboring conspecific adults on seedling survival. In addition, we found that interspecific variation in CNDD was related to drought-tolerant traits in the dry season but not in the rainy season. Across years, we found that drought-intolerant species suffer less CNDD during the dry seasons that have higher rainfall, whereas drought-tolerant species suffer less CNDD when the dry season has lower rainfall. We also found that rare species suffered stronger CNDD in the dry season. Overall, our study highlights that CNDD is highly variable among species and through time, necessitating a deeper appreciation of the environmental and functional contexts of CNDD and their interactions.

Intraspecific variation in Janzen-Connell effect is mediated by stress and plant-soil feedbacks.

Janzen-Connell (JC) effects, hypothesized to be partially driven by negative plant-soil feedbacks (PSFs), are considered to be a key mechanism that regulates tropical forest plant diversity and coexistence. However, intraspecific variation in JC effects may weaken this mechanism, with the strength of PSFs being a potentially key variable process. We conducted a manipulated experiment with seedlings from two populations of Pometia pinnata (Sapindaceae), a tropical tree species in southwest China. We aimed to measure the intraspecific difference in PSF magnitude caused by inoculating the soil from different P. pinnata source populations and growing seedlings under differing light intensity and water availability treatments, and at varying plant densities. We found negative PSFs for both populations with the inoculum soil originating from the same sites, but PSFs differed significantly with the inoculum soil from different sites. PSF strength responded differently to biotic and abiotic drivers; PSF strength was weaker in low moisture and high light treatments than in high moisture and low light treatments. Our study documents intraspecific variation in JC effects: specifically, P. pinnata have less defenses to their natively-sourced soil, but are more defensive to the soil feedbacks from soil sourced from other populations. Our results imply that drought and light intensity tended to weaken JC effects, which may result in loss of species diversity with climate change.

Efficient characterizations of multiphoton states with an ultra-thin optical device.

Metasurface enables the generation and manipulation of multiphoton entanglement with flat optics, providing a more efficient platform for large-scale photonic quantum information processing. Here, we show that a single metasurface optical device would allow more efficient characterizations of multiphoton entangled states, such as shadow tomography, which generally requires fast and complicated control of optical setups to perform information-complete measurements, a demanding task using conventional optics. The compact and stable device here allows implementations of general positive operator valued measures with a reduced sample complexity and significantly alleviates the experimental complexity to implement shadow tomography. Integrating self-learning and calibration algorithms, we observe notable advantages in the reconstruction of multiphoton entanglement, including using fewer measurements, having higher accuracy, and being robust against experimental imperfections. Our work unveils the feasibility of metasurface as a favorable integrated optical device for efficient characterization of multiphoton entanglement, and sheds light on scalable photonic quantum technologies with ultra-thin optical devices.

Downregulation of UBB potentiates SP1/VEGFA-dependent angiogenesis in clear cell renal cell carcinoma.

Clear cell renal cell carcinoma (ccRCC) presents a unique profile characterized by high levels of angiogenesis and robust vascularization. Understanding the underlying mechanisms driving this heterogeneity is essential for developing effective therapeutic strategies. This study revealed that ubiquitin B (UBB) is downregulated in ccRCC, which adversely affects the survival of ccRCC patients. UBB exerts regulatory control over vascular endothelial growth factor A (VEGFA) by directly interacting with specificity protein 1 (SP1), consequently exerting significant influence on angiogenic processes. Subsequently, we validated that DNA methyltransferase 3 alpha (DNMT3A) is located in the promoter of UBB to epigenetically inhibit UBB transcription. Additionally, we found that an unharmonious UBB/VEGFA ratio mediates pazopanib resistance in ccRCC. These findings underscore the critical involvement of UBB in antiangiogenic therapy and unveil a novel therapeutic strategy for ccRCC.

Scalable parallel ultrafast optical random bit generation based on a single chaotic microcomb.

Random bit generators are critical for information security, cryptography, stochastic modeling, and simulations. Speed and scalability are key challenges faced by current physical random bit generation. Herein, we propose a massively parallel scheme for ultrafast random bit generation towards rates of order 100 terabit per second based on a single micro-ring resonator. A modulation-instability-driven chaotic comb in a micro-ring resonator enables the simultaneous generation of hundreds of independent and unbiased random bit streams. A proof-of-concept experiment demonstrates that using our method, random bit streams beyond 2 terabit per second can be successfully generated with only 7 comb lines. This bit rate can be easily enhanced by further increasing the number of comb lines used. Our approach provides a chip-scale solution to random bit generation for secure communication and high-performance computation, and offers superhigh speed and large scalability.

Repetition rate tuning and locking of solitons in a microrod resonator.

Recently, there has been significant interest in the generation of coherent temporal solitons in optical microresonators. In this Letter, we present a demonstration of dissipative Kerr soliton generation in a microrod resonator using an auxiliary-laser-assisted thermal response control method. In addition, we are able to control the repetition rate of the soliton over a range of 200 kHz while maintaining the pump laser frequency, by applying external stress tuning. Through the precise control of the PZT voltage, we achieve a stability level of 3.9 × 10-10 for residual fluctuation of the repetition rate when averaged 1 s. Our platform offers precise tuning and locking capabilities for the repetition frequency of coherent mode-locked combs in microresonators. This advancement holds great potential for applications in spectroscopy and precision measurements.

Improving the Laser-Induced Breakdown Spectroscopy for Highly Efficient Trace Measurement of Hazardous Components in Waste Oils.

Improper disposal of waste oils containing hazardous components damages the environment and the ecosystem, posing a significant threat to human life and health. Here, we present a method of discharge-assisted laser-induced breakdown spectroscopy combined with filter paper sampling (DA-LIBS-FPS) to detect hazardous components and trace the source of polluting elements. DA-LIBS-FPS significantly enhances spectral intensity by 1-2 orders of magnitude due to the discharge energy deposition into the laser-induced plasma and the highly efficient laser-sample interaction on the filter paper, when compared to single-pulse LIBS with silica wafer sampling (SP-LIBS-SWS). Additionally, the signal-to-noise ratio and the signal-to-background ratio are both significantly increased. Resultantly, indiscernible lines, such as CN and Cr I, are well distinguished. In contrast with DA-LIBS combined with silica wafer sampling (DA-LIBS-SWS), the spectral signal fluctuations in DA-LIBS-FPS are reduced by up to 33%, because of the homogeneous distribution of the oil layer on the filter paper in FPS. Further examination indicates that the limit of detection for Ba is reduced from a several parts per million level in SP-LIBS-SWS to a dozens of parts per billion level in DA-LIBS-FPS, i.e., nearly 2 orders of magnitude enhancement in analysis sensitivity. This improvement is attributed to the extended plasma lifespan in DA-LIBS and the increasing electron density and plasma temperature in FPS. DA-LIBS-FPS provides a low-cost, handy, rapid, and highly sensitive avenue to analyze the hazardous components in waste oils with great potential in environmental and ecological monitoring.

Polarization-multiplexed metasurface enabled tri-functional imaging.

Diffraction-limited focusing imaging, edge-enhanced imaging, and long depth of focus imaging offer crucial technical capabilities for applications such as biological microscopy and surface topography detection. To conveniently and quickly realize the microscopy imaging of different functions, the multifunctional integrated system of microscopy imaging has become an increasingly important research direction. However, conventional microscopes necessitate bulky optical components to switch between these functionalities, suffering from the system's complexity and unstability. Hence, solving the problem of integrating multiple functions within an optical system is a pressing need. In this work, we present an approach using a polarization-multiplexed tri-functional metasurface, capable of realizing the aforementioned imaging functions simply by changing the polarization state of the input and output light, enhancing the system structure's compactness and flexibility. This work offers a new avenue for multifunctional imaging, with potential applications in biomedicine and microscopy imaging.

Pangenome analysis provides insight into the evolution of the orange subfamily and a key gene for citric acid accumulation in citrus fruits.

The orange subfamily (Aurantioideae) contains several Citrus species cultivated worldwide, such as sweet orange and lemon. The origin of Citrus species has long been debated and less is known about the Aurantioideae. Here, we compiled the genome sequences of 314 accessions, de novo assembled the genomes of 12 species and constructed a graph-based pangenome for Aurantioideae. Our analysis indicates that the ancient Indian Plate is the ancestral area for Citrus-related genera and that South Central China is the primary center of origin of the Citrus genus. We found substantial variations in the sequence and expression of the PH4 gene in Citrus relative to Citrus-related genera. Gene editing and biochemical experiments demonstrate a central role for PH4 in the accumulation of citric acid in citrus fruits. This study provides insights into the origin and evolution of the orange subfamily and a regulatory mechanism underpinning the evolution of fruit taste.

Suppressing grating lobes of large-aperture optical phased array with circular array design.

An optical phased array (OPA), especially a two-dimensional (2D) OPA, suffers from the trade-off among steering range, beam width, and the number of antennas. Aperiodic 2D array designs currently aimed to reduce the number of antennas and reduce grating lobes within a wide range fall short when an aperture approaches millimeter size. A circular OPA design is proposed to address this issue. The circular design substantially reduces the number of antennas while achieving the same wide steering range and narrow beam width of optimized aperiodic 2D OPA designs. Its efficient suppression of grating lobes, the key to a wide steering range with minimal number of antennas and large antenna spacing, is theoretically studied and validated by simulation. The novel, to the best of our knowledge, design allows less than 100 antennas, orders of magnitude reduction, for millimeter size aperture OPA designs. It paves the way for commercialization by significantly reducing control complexity and power consumption.

Hybrid integrated narrow-linewidth semiconductor lasers.

Integrated narrow-linewidth lasers are the key devices in compact coherent optical systems of metrology, sensing, and optical microwave generation. Here, we demonstrate a hybrid integrated laser based on an optical negative feedback scheme. The laser is composed of a commercial distributed feedback (DFB) laser diode and an on-chip micro-resonator with a Q-factor of 0.815 million. The feedback optical field is coupled back to the laser cavity through the back facet. Therefore, the laser can maintain the lasing efficiency of the DFB laser diode. The linewidth of the DFB laser diode is compressed from 2 MHz to 6 kHz, corresponding to the linewidth reduction factor of 25.2 dB. The theoretical result shows that the laser performance still has a huge improvement margin through precise control of the detuning between laser frequency and the micro-resonator, as well as the phase delay of the feedback optical field. The hybrid narrow-linewidth laser diode has wide application prospects in coherent optical systems benefitting from the low cost and volume productivity.

Micrometer-precision absolute distance measurement with a repetition-rate-locked soliton microcomb.

The soliton microcomb has sparked interest in high-precision distance measurement, owing to its ultrahigh repetition rate and chip-integrated scale. We report absolute distance measurements based on synthetic wavelength interferometry with a soliton microcomb. We stabilized the repetition rate of 48.98 GHz through injection locking, with fluctuations below 0.25 Hz. Distance measurements up to 64 mm were demonstrated, presenting residuals below 2.7 µm compared with a referenced laser interferometer. Long-term distance measurements were made at two fixed positions of approximately 0.2 m and 1.4 m, resulting in a minimum Allan deviation as low as 56.2 nm at an average time of 0.05 s. The dynamic demonstration illustrated that the proposed system could track round-trip motion of 3 mm at speeds up to 100 mm/s. The proposed distance measurement system is, to our knowledge, the first microcomb-based synthetic wavelength interferometer and achieves a ranging precision of tens of nanometers, with potential applications in the fields of satellite formation flying, high-end manufacturing, and micro-nano processing.

Routing to mid-infrared microcomb via near-infrared direct pump.

Mid-infrared (MIR) microcomb provides a new way into the "molecular fingerprint" region. However, it remains rather a challenge to realize the broadband mode-locked soliton microcomb, which is often limited by the performance of available MIR pump sources and coupling devices. Here, we propose an effective approach towards broadband MIR soliton microcombs generation via a direct pump in the near-infrared (NIR) region, through full utilization of the second- and third-order nonlinearities in a thin-film lithium niobate microresonator. The optical parametric oscillation process contributes to conversion from the pump at 1550 nm to the signal around 3100 nm, and the four-wave mixing effect promotes spectrum expansion and mode-locking process. While the second-harmonic and sum-frequency generation effects facilitate simultaneous emission of the NIR comb teeth. Both the continuous wave and pulse pump sources with relatively low power can support a MIR soliton with a bandwidth over 600 nm and a concomitant NIR microcomb with a bandwidth of 100 nm. This work can provide a promising solution for broadband MIR microcombs by breaking through the limitation of available MIR pump sources, and can deepen the understanding of the physical mechanism of the quadratic soliton assisted by the Kerr effect.

Protective role of remote ischemic conditioning in renal transplantation and partial nephrectomy: A systematic review and meta-analysis of randomized controlled trials.

Objective: Studies have shown that remote ischemic conditioning (RIC) can effectively attenuate ischemic-reperfusion injury in the heart and brain, but the effect on ischemic-reperfusion injury in patients with kidney transplantation or partial nephrectomy remains controversial. The main objective of this systematic review and meta-analysis was to investigate whether RIC provides renal protection after renal ischemia-reperfusion injury in patients undergoing kidney transplantation or partial nephrectomy. Methods: A computer-based search was conducted to retrieve relevant publications from the PubMed database, Embase database, Cochrane Library and Web of Science database. We then conducted a systematic review and meta-analysis of randomized controlled trials that met our study inclusion criteria. Results: Eleven eligible studies included a total of 1,145 patients with kidney transplantation or partial nephrectomy for systematic review and meta-analysis, among whom 576 patients were randomly assigned to the RIC group and the remaining 569 to the control group. The 3-month estimated glomerular filtration rate (eGFR) was improved in the RIC group, which was statistically significant between the two groups on kidney transplantation [P < 0.001; mean difference (MD) = 2.74, confidence interval (CI): 1.41 to 4.06; I 2 = 14%], and the 1- and 2-day postoperative Scr levels in the RIC group decreased, which was statistically significant between the two groups on kidney transplantation (1-day postoperative: P < 0.001; MD = 0.10, CI: 0.05 to 0.15, I 2 = 0; 2-day postoperative: P = 0.006; MD = 0.41, CI: 0.12 to 0.70, I 2 = 0), but at other times, there was no significant difference between the two groups in Scr levels. The incidence of delayed graft function (DGF) decreased, but there was no significant difference (P = 0.60; 95% CI: 0.67 to 1.26). There was no significant difference between the two groups in terms of cross-clamp time, cold ischemia time, warm ischemic time, acute rejection (AR), graft loss or length of hospital stay. Conclusion: Our meta-analysis showed that the effect of remote ischemia conditioning on reducing serum creatinine (Scr) and improving estimate glomerular filtration rate (eGFR) seemed to be very weak, and we did not observe a significant protective effect of RIC on renal ischemic-reperfusion. Due to small sample sizes, more studies using stricter inclusion criteria are needed to elucidate the nephroprotective effect of RIC in renal surgery in the future.

Canopy height, rather than neighborhood effects, shapes leaf herbivory in a tropical rainforest.

Factors shaping the interspecific variations in herbivory have puzzled ecologists for decades and several hypotheses have been proposed to explain interspecific variation in leaf herbivory. In a tropical rainforest in Yunnan Province, China, we collected 6732 leaves from 129 species with canopy heights ranging from 1.6 to 65.0 m above the ground. We tested the role of canopy height, the diversity, composition and structural heterogeneity of neighbors and leaf traits in shaping the interspecific variations in herbivory. Results show that leaf herbivory decreased with canopy height and specific leaf area (SLA) and increased with leaf size. However, neighboring species' diversity, composition, and structural heterogeneity showed no association with herbivory. Therefore, neither the visual apparency effect nor the associational resistance effect was detected in this hyperdiverse tropical rainforest. These findings highlight the importance of vertical structure in shaping herbivory patterns in natural communities.

Tropical-temperate comparisons in insect seed predation vary between study levels and years.

The biotic interaction hypothesis, which states the species interaction becomes stronger in the tropics, is deeply rooted in classic ecological literature and widely accepted to contribute to the latitudinal gradients of biodiversity. Tests in latitudinal insect-plant interaction have emphasized leaf-eating insects on a single or a few plant species rather than within an entire community and mixed accumulating evidence, leaving the biotic interaction hypothesis disputed. We aimed to test the hypothesis by quantifying insect seed predation in a pair of tropical and temperate forest communities with similar elevations. We applied a consistent study design to sample predispersal seeds with systematically set seed traps in 2019-2020 and examined internally feeding insects. The intensity of seed predation was measured and further applied to tropical versus temperate comparison at two levels (cross-species and community-wide). Our results showed every latitudinal pattern associated with different study levels and years, that is, negative (greater granivory in the tropics in community-wide comparison in 2020), positive (less granivory in the tropics in community-wide and cross-species comparison in 2019), and missing (similar level of granivory in the tropics in cross-species comparisons in 2020). The cross-species level analyses ignore differences among species in seed production and weaken or even lose the latitudinal trend detected by community-wide comparisons. The between-year discrepancy in tropical-temperate comparisons relates to the highly variable annual seed composition in the temperate forest due to mast seeding of dominant species. Our study highlights that long-term community-level researches across biomes are essential to assess the latitudinal biotic interaction hypothesis.

Changes in the Structural Composition and Moisture-Adsorption Properties of Mechanically Rolled Bamboo Fibers.

The chemical content, mechanical capability, and dimensional stability of bamboo fibers (BFs) are all directly related to the hygroscopic behavior, which is crucial for industrial applications. To support the utilization of BFs, the structural and chemical composition of BFs with different opening times after mechanical rolling were investigated in this study, and the Guggenheim-Anderson-de Boer (GAB) model was selected to predict their moisture-adsorption properties. The results showed that the length and diameter of the fibers gradually decreased with the increase in the number of openings, and the fibers gradually separated from bundles into single fibers. It was also observed that the treated BFs exhibited different equilibrium moisture contents (EMCs). BFs with a smaller number of openings had a higher hemicellulose content and more exposed parenchyma cells on the fibers, which increased the number of water adsorption sites. As the number of openings increased, the parenchyma cells on the fibers decreased, and the lignin content increased, which reduced the number of fiber moisture-adsorption sites and decreased the EMC of the fibers.

Intramolecular Partners in Asymmetric Catalysis Copolymerization: Highly Enantioselective and Controllable at Enhanced Temperatures and Low Loadings.

Asymmetric copolymerization of meso-epoxide and anhydride is a powerful strategy for preparing various isotactic polyesters with two contiguous stereogenic centers. However, the previous binary systems suffered from slow rates at low loadings, poor enantioselectivities and transesterification reactions at enhanced temperatures. Herein, we report novel dinuclear aluminium complexes with multiple chiralities and ammonium salts anchored on ligand frameworks. These bifunctional catalysts exhibit high activities and enantioselectivities for epoxides/anhydrides copolymerizations at harsh conditions via intramolecularly synergistic catalysis, affording polyesters with unprecedented molecular weights and narrow distributions. Notably, no transesterification reactions were observed, significantly different from the binary catalyst/cocatalyst pairs. This study represents a rare example regarding temperature-independent asymmetric induction for preparing chiral polymers from achiral monomers.

Experimental demonstration of optical trapping and manipulation with multifunctional metasurface.

Chip-scale optical tweezers, which are usually implemented in a planar format without using bulky diffractive optical elements, are recognized as a promising candidate to be integrated with a lab-on-a-chip system. However, traditional chip-scale optical tweezers are often static and allow for only one type of manipulation functionality since the geometrical parameters of the tweezers are fixed. Herein, we introduce a new, to the best of our knowledge, class of on-chip optical tweezers for diverse types of manipulation of micro-particles. Utilizing both the propagation phase and Pancharatnam-Berry phase, we experimentally demonstrate the spin-dependent trapping, moving, and circling of micro-particles with the transfer of optical gradient force and orbital angular momentum to particles. We further show that the spin angular momentum of the output beam provides an additional degree of freedom to control the spinning rotation of particles. This new type of optical tweezers paves the way for multifunctional and dynamical trapping and manipulation of particles with a lab-on-a-chip system.