Browse Articles

Nearest neighbor permutation entropy detects phase transitions in complex high-pressure systems

Repeated occurrences of marine anoxia under high atmospheric O ₂ and icehouse conditions

The Late Paleozoic Ice Age (~340 to 260 Ma) occurred under peak atmospheric O 2 (1.2 to 1.7 PIAL, pre-industrial atmospheric levels) for Earth history and CO 2 concentrations comparable to those of the preindustrial to that anticipated for our near future. The evolution of the marine redox landscape under these conditions remains largely unexplored, reflecting that oceanic anoxia has long been considered characteristic of carbon cycle perturbation during greenhouse times. Despite elevated O 2 , a 10 5 -y period of CO 2 -forced oceanic anoxia was recently identified, but whether this short-term interval of widespread oceanic anoxia was anomalous during this paleo-ice age is unexplored. Here, we investigate these issues by building a high-resolution record of carbonate uranium isotopes (δ 238 U carb ) from an open-marine succession in South China that permits us to reconstruct the global marine redox evolution through the deep glacial interval (310 to 290 Ma) of near peak O 2 . Our data reveal repeated, short-term decreases in δ 238 U carb coincident with negative C isotopic excursions and rises in paleo-CO 2 , all superimposed on a longer-term rise in δ 238 U carb . A carbon–phosphorus–uranium biogeochemical model coupled with Bayesian inversion is employed to quantitatively explore the interplay between marine anoxia, carbon cycling, and climate evolution during this paleo-glacial period. Although our results indicate that protracted, enhanced organic carbon burial can account for the long-term O 2 increase, seafloor oxygenation, and overall low CO 2 , episodic pulses of C emissions had the potential to drive recurring short-term periods of marine anoxia (with 4 to 12% of seafloor anoxia) despite up to 1.7 times higher atmospheric O 2 than present day.

Multi-dimensional visual information processing under complex light environments using time-evolved polarization-sensitive synaptic electronics

Imbalanced TGFβ signalling and autophagy drive erythroid priming of hematopoietic stem cells in β-thalassemia

Silver exsolution from Li-argyrodite electrolytes for initially anode-free all-solid-state batteries

Synthesis of Nitriles from Dinitrogen via N‐Atom Transfer on Rhenium Nitride Complex

Abstract Transition‐metal mediated dinitrogen (N 2 ) splitting into terminal nitrido moiety followed by N‐atom transfer is an attractive strategy for N 2 fixation beyond ammonia. While the functionalization of N 2 ‐derived nitride complexes have been widely investigated, their N‐atom transfer reactions to provide N‐containing organic compounds were rarely reported. Herein, we report the synthesis of a rhenium nitride complex [( acri PNP)Re(N)Cl] ( acri PNP = 4,5‐bis(diisopropylphosphino)‐2,7,9,9‐tetramethyl‐9H‐acridin‐10‐ide) via reductive N 2 cleavage from either rhenium trichloride or rhenium oxo dichloride complexes. The rhenium nitride exhibits N‐atom transfer reactivity with acyl triflates or chlorides under mild conditions, affording nitriles concomitant with the regeneration of the nitride precursors, rhenium oxo or trichloride complexes, respectively. This overall N‐atom transfer from N 2 to acyl electrophiles produced a series of alkyl, aryl, and heterocyclic nitriles, in moderate to good yields, offering a versatile and practical strategy for accessing 15 N‐labeled nitriles. This work established a two‐step synthetic cycle, offering valuable insights into transformations of N 2 into nitrogenous products.

Fast charging coordination for electric vehicles in a charging station based on heuristics and metaheuristics

A dual-domain perception gate-controlled adaptive fusion algorithm for road crack detection

Multiple subcortical and subcortico–cortico dynamic network reconfigurations characterize focal-to-bilateral tonic–clonic seizures

A novel decision-making approach for the selection of best deep learning techniques under logarithmic fractional fuzzy set information

Investigation of mechanical and metallurgical properties of commercially pure titanium grade 2 tube-to-tubesheet joints

Multiphysics coupling analysis and structure optimization of flux switching permanent magnet linear motors

Optimization of thermal barrier coating with induced copper oxide nanoparticles in CI engine using algae methyl ester as fuel

Morphometric analysis of rat and mouse musculoskeletal tissues using high field MRI

Abstract The knee is a complex articulating joint composed of bones and fibrous connective tissues with anatomy retained across species including humans, pigs, dogs, rats, and mice. Imaging developments in high field magnetic resonance imaging (MRI) has enabled non-destructive 3D structural analysis of small animal joints to further these preclinical models. The goal of this work was to apply MRI techniques for rodent knee joints using a high field MRI scanner and to characterize the morphometry of the four primary ligaments and medial and lateral menisci. Briefly, female rat and mouse knees were imaged in a 9.4T MRI scanner and the cross-sectional area (CSA) of the ligaments and the meniscal heights and widths were recorded. Tissue dependent relationships were observed in the rat and mouse ligaments. The PCL was the largest ligament in the rats with a CSA of 0.35 ± 0.08 mm 2 , while the LCL was the largest ligament in the mice, with a CSA of 0.054 ± 0.017 mm 2 . Rat and mouse meniscal width had an anatomical location dependent relationship, while meniscal height did not. This will support future work exploring morphometric effects due to aging, injury, and disease in preclinical animal models.

A bioinspired and degradable riboflavin-containing polypeptide as a sustainable material for energy storage

Inspired by Nature, we present a polypeptide-based organic redox-active material constructed from renewable feedstocks, L-glutamic acid (an amino acid) and riboflavin (vitamin B 2 ), to address challenges with start-to-end-of-life management in energy storage systems (ESSs). The amino acid was utilized to establish a degradable polymer backbone, along which many copies of riboflavin were incorporated to serve as the redox-active pendant groups that enabled energy storage. The overall synthesis involved the ring-opening polymerization (ROP) of an l -glutamic acid-derived N- carboxyanhydride (NCA) monomer, followed by side chain activation with azides and, finally, click coupling to achieve installation of alkyne-functionalized riboflavin moieties. The steric bulkiness and rich chemical functionality of riboflavin resulted in synthetic complexities that required reaction optimization to achieve the desired polymer structure. Electrochemical characterization of the resultant riboflavin polypeptide, in organic electrolyte, showed quasireversible redox activity with a half-wave potential (E 1/2 ) of ca. −1.10 V vs. ferrocene/ferrocenium (Fc/Fc + ). Cell viability assays revealed biocompatibility, as indicated by negligible cytotoxicity for fibroblast cells. The polypeptide design, consisting of labile amide backbone linkages and side-chain ester functionalities that tethered the riboflavin units to the backbone, enabled hydrolytic degradation to recover building blocks for future upcycling or recycling. This bioinspired strategy advances the development of degradable redox-active polymers and promotes sustainable materials design for circular energy storage technologies.

Maximal response to a mechanical leader at critical group size in ant collectives

Abstract It is widely recognized that biological collectives operate near criticality to amplify their capability of collective response. The peak in susceptibility near criticality renders these groups highly responsive to external stimuli. While this phenomenon has been recognized and supported by evidence from theory, a direct experimental demonstration has been elusive. To bridge this gap, here we record the response of a group of Paratrechina longicornis ants to external stimuli as they join efforts to carry food to their nest. Using a robotic system that mimics a transient leader, we apply tactile ant-scale forces and measure the group’s response at sub, near, and supercritical regimes. Supported by theory and simulations, we provide direct experimental evidence to demonstrate that at critical group size, the collective response of the ants to an external force is maximally amplified.

Stereodivergent synthesis of benzylic alcohol derivatives enabled by Pd/Cu co-catalyzed asymmetric benzylic substitution reaction

Low-temperature sequential deposition for efficient inverted perovskite solar cells

Iron‐Doped Cobalt Molybdate Enhanced Electrochemiluminescence Imaging for Dynamic Multilevel Information Encryption System Construction and Biomarker Sensing Analysis

Abstract Integrating electrochemiluminescence (ECL) imaging with a multilevel information encryption strategy overcomes the limitations of conventional encryption methods, which rely solely on abstract electrical signals, by providing intuitive visual outputs. Herein, a dynamic multilevel information encryption system based on ECL imaging was successfully constructed, which realizes robust protection and precisely controlled decryption of information through the multidimensional security mechanism of “biometrics (biospecific recognition of the primary key) – electrochemical activation (precise voltage‐triggered activation of the secondary key) – operational sequence dependence (strict matching of the operational timing)–signal gradient (decryptor judgment)”. Specifically, we develop a functional chemical ink comprised of iron‐doped cobalt molybdate and biomolecules, which is applied onto nitrocellulose membranes via micro‐patterned printing to construct biocompatible, environmentally responsive encryption interfaces. Density‐functional theory calculations indicate that iron‐doped cobalt molybdate accelerates the conversion of tripropylamine (TPrA) into TPrA radicals, forming a signal gradient with the cobalt molybdate catalytic region and thereby further enhancing the dimensionality of information encryption. Furthermore, a chemical ink‐based ECL sensor was developed for ultra‐sensitive detection of the cancer biomarker CA15‐3, demonstrating the dual potential application in biomedical information security and disease diagnosis.

A modified generative adversarial networks method for assisting the diagnosis of deep venous thrombosis complications in stroke patients