Electrochemical polymer synthesis usually forms dense films bound to the electrode. We report a single-step synthesis of large-area, ultrathin (~70-nanometer) polymeric membranes with a luffa-like, reticular cross-linked network with low density (0.5 grams per cubic centimeter). This particular membrane forms within an electric double layer in water constructed by voltage application without supporting electrolytes—in which deprotonated resorcinol and an aldehyde react three-dimensionally with a self-termination mechanism—and is spontaneously released when the voltage bias is removed. Initially rigid with a Young’s modulus of 8.9 gigapascals, this membrane reversibly regains flexibility (0.5 gigapascals) upon wetting and can be used as a large-area membrane for separations. Its shape-persistent carbonization made it possible to yield ultrathin (~22-nanometer) nanoporous carbon membranes.
古人类学Paleoanthropology
300,000-year-old wooden tools from Gantangqing, southwest China
Evidence of Early and Middle Pleistocene wooden implements is exceptionally rare, and existing evidence has been found only in Africa and western Eurasia. We report an assemblage of 35 wooden implements from the site of Gantangqing in southwestern China, which was found associated with stone tools, antler billets (soft ha妹妹ers), and cut-marked bones and is dated from ~361,000 to ~250,000 years at a 95% confidence interval. The wooden implements include digging sticks and small, complete, hand-held pointed tools. The sophistication of many of these tools offsets the seemingly “primitive” aspects of stone tool assemblages in the East Asian Early Paleolithic. This discovery suggests that wooden implements might have played an important role in hominin survival and adaptation in Middle Pleistocene East Asia.
Recognizing familiar individuals is crucial for adaptive social interactions among animals. However, the multidimensional nature of social memory encompassing sexual information remains unelucidated. We found that neurons in the ventral CA1 region (vCA1) of the mouse hippocampus encoded the identities and social properties, specifically sex and strain, of familiar conspecifics by using both rate and theta-based temporal coding. Optogenetic reactivation of social memories of females, but not males, induced place preference. Ablation of the upstream hippocampal dorsal CA2 region or the medial amygdala disrupted the representation of sex and the sexual dichotomy of social memory valence. Thus, vCA1 neurons use dual coding schemes to represent the identities and social properties of familiar conspecifics as a cohesive memory.
植物学Zoology
Consistent energy-diversity relationships in terrestrial vertebrates
Anyons are quasiparticles that keep a robust memory of particle exchanges via a braiding phase factor. When an anyon excitation is emitted toward a quantum point contact (QPC) in a fractional quantum Hall (FQH) fluid, this memory translates into tunneling events that may occur long after the anyon excitation has exited the QPC. In this work, we used triggered anyon pulses incident on a QPC in a filling factor ν = 1/3 FQH fluid to investigate anyon tunneling in the time domain. We observed that braiding increases the tunneling timescale, which is set by the temperature and the anyon scaling dimension that characterizes the edge-state dynamics. Our experiment introduces time-domain measurements for characterizing the braiding phase and scaling dimension of anyons.
生物学Biology
Representation of sex-specific social memory in ventral CA1 neurons
腹侧CA1神经元的性别特异性社会影像表征
▲ 作者：Akiyuki Watarai, Kentaro Tao, and Teruhiro Okuyama
Climate and ecosystem dynamics vary across timescales, but research into climate-driven vegetation dynamics usually focuses on singular timescales. We developed a spectral analysis–based approach that provides detailed estimates of the timescales at which vegetation tracks climate change, from 101 to 105 years. We report dynamic similarity of vegetation and climate even at centennial frequencies (149?1to 18,012?1year?1, that is, one cycle per 149 to 18,012 years). A breakpoint in vegetation turnover (797?1year?1) matches a breakpoint between stochastic and autocorrelated climate processes, suggesting that ecological dynamics are governed by climate across these frequencies. Heightened vegetation turnover at millennial frequencies (4650?1year?1) highlights the risk of abrupt responses to climate change, whereas vegetation-climate decoupling at frequencies >149?1year?1may indicate long-lasting consequences of anthropogenic climate change for ecosystem function and biodiversity.
质料迷信Material Sciences
Electric double-layer synthesis of a spongelike, lightweight reticular membrane
Ecologists have long proposed that environments providing more energy can support more species, yet empirical evidence frequently contradicts this expectation. We argue that such inconsistencies result from confounding geographical influences that mask the true relationship between species richness and energy-related factors. Here, by comparing species richness across different climate conditions, we disentangle the direct effects of temperature, precipitation, and primary productivity from the confounding impacts of the area and isolation of various climates. Using a global analysis of terrestrial vertebrates, we reveal clear and consistent relationships between energy-related factors and species richness. Our findings clarify existing ecological theory and illustrate how adopting a climate space perspective advances biodiversity research, providing critical insights into biodiversity patterns and their responses to environmental change.
地球迷信Earth Science
Coupled, decoupled, and abrupt responses of vegetation to climate across timescales
