The promise of cancer immunotherapy has not been translated into clinical successes, in large part because of tumor-associated immune suppression that blocks effective antitumor immunity. Recent ...findings show a tumor-induced immunosuppressive mechanism, whereby tumor-derived CD73 functions as an ecto-enzyme to produce extracellular adenosine, which promotes tumor growth by limiting antitumor T-cell immunity via adenosine receptor signaling. Results with small molecule inhibitors, or monoclonal antibodies targeting CD73 in murine tumor models, suggest that targeted CD73 therapy is an important alternative and realistic approach to effective control of tumor growth. In particular, it helps T-cell-based therapy by enhancing the adaptive immune response machinery, which may increase the function of tumor-infiltrating T lymphocytes, and subsequently lead to improved survival in cancer patients.
The urgent need of clean and renewable energy drives the exploration of effective strategies to produce molecular hydrogen. With the assistance of highly active non-noble metal electrocatalysts, ...electrolysis of water is becoming a promising candidate to generate pure hydrogen with low cost and high efficiency. Very recently, transition metal phosphides (TMPs) have been proven to be high performance catalysts with high activity, high stability, and nearly ∼100% Faradic efficiency in not only strong acidic solutions, but also in strong alkaline and neutral media for electrochemical hydrogen evolution. In this tutorial review, an overview of recent development of TMP nanomaterials as catalysts for hydrogen generation with high activity and stability is presented. The effects of phosphorus (P) on HER activity, and their synthetic methods of TMPs are briefly discussed. Then we will demonstrate the specific strategies to further improve the catalytic efficiency and stability of TMPs by structural engineering. Making use of TMPs as cocatalysts and catalysts in photochemical and photoelectrochemical water splitting is also discussed. Finally, some key challenges and issues which should not be ignored during the rapid development of TMPs are pointed out. These strategies and challenges of TMPs are instructive for designing other high-performance non-noble metal catalysts.
This tutorial review provides an overview of recent development of TMP nanomaterials as catalysts for hydrogen generation with high activity and stability.
The repeating fast radio burst (FRB) source that produced FRB 121102 was recently localized in a star-forming galaxy at z = 0.193, which is associated with an extended radio source at the burst ...location. One possibility is that the repeating FRBs are produced by a new-born magnetar, which also powers the radio nebula. If so, the magnetar may produce γ-ray emission due to magnetic dipolar spin-down. The luminosity depends on the magnetar spin parameters and age. We process the eight-year Fermi-LAT data at the position of FRB 121102 and place an energy flux upper limit of in time bins with six-month intervals, and an accumulated energy flux upper limit of over the eight-year span. The corresponding γ-ray luminosity upper limits are and for the time-resolved and time-integrated analyses, respectively. We discuss the implications of these limits on the young magnetar model.
Room‐temperature sodium–sulfur (RT‐Na/S) batteries hold significant promise for large‐scale application because of low cost of both sodium and sulfur. However, the dissolution of polysulfides into ...the electrolyte limits practical application. Now, the design and testing of a new class of sulfur hosts as transition‐metal (Fe, Cu, and Ni) nanoclusters (ca. 1.2 nm) wreathed on hollow carbon nanospheres (S@M‐HC) for RT‐Na/S batteries is reported. A chemical couple between the metal nanoclusters and sulfur is hypothesized to assist in immobilization of sulfur and to enhance conductivity and activity. S@Fe‐HC exhibited an unprecedented reversible capacity of 394 mAh g−1 despite 1000 cycles at 100 mA g−1, together with a rate capability of 220 mAh g−1 at a high current density of 5 A g−1. DFT calculations underscore that these metal nanoclusters serve as electrocatalysts to rapidly reduce Na2S4 into short‐chain sulfides and thereby obviate the shuttle effect.
Enhancing sulfur: Transition‐metal nanoclusters (ca. 1.2 nm) wreathed on hollow carbon nanospheres as S hosts were applied to enhance conductivity and activity of sulfur. These nanoclusters chemisorb the resultant polysulfide and electrocatalyze these into short‐chain sulfides, thus achieving excellent cycling stability and rate performance for room‐temperature sodium–sulfur batteries.
Forests in the Tibetan Plateau are thought to be vulnerable to climate extremes, yet they also tend to exhibit resilience contributing to the maintenance of ecosystem services in and beyond the ...plateau. So far the spatiotemporal pattern in tree resilience in the Tibetan Plateau remains largely unquantified and the influence of specific factors on the resilience is poorly understood. Here, we study ring‐width data from 849 trees at 28 sites in the Tibetan Plateau with the aim to quantify tree resilience and determine their diving forces. Three extreme drought events in years 1969, 1979, and 1995 are detected from metrological records. Regional tree resistance to the three extreme droughts shows a decreasing trend with the proportion of trees having high resistance ranging from 71.9%, 55.2%, to 39.7%. Regional tree recovery is increasing with the proportion of trees having high recovery ranging from 28.3%, 52.2%, to 64.2%. The area with high resistance is contracting and that of high recovery is expanding. The spatiotemporal resistance and recovery are associated with moisture availability and diurnal temperature range, respectively. In addition, they are both associated with forest internal factor represented by growth consistence among trees. We conclude that juniper trees in the Tibetan Plateau have increased resilience to extreme droughts in the study period. We highlight pervasive resilience in juniper trees. The results have implications for predicting tree resilience and identifying areas vulnerable to future climate extremes.
Tree resilience is important for maintaining the healthy growth of forests, yet remains largely unquantified. Examination of tree resilience to drought extremes from 28 sites of juniper forests in the Tibetan Plateau reveals a temporal decreasing trend in tree resistance and an increasing trend in recovery, and a spatial contraction in the area of high resistance and expansion in high recovery. The variation of tree resilience is associated with moisture availability, diurnal temperature range, and growth consistence among trees. The results have implications for predicting tree resilience and identifying areas vulnerable to future climate extremes.
2D transition metal carbides and nitrides (MXenes) have gained extensive attention recently due to their versatile surface chemistry, layered structure, and intriguing properties. The assembly of ...MXene sheets into macroscopic architectures is an important approach to harness their extraordinary properties. However, it is difficult to construct a freestanding, mechanically flexible, and 3D framework of MXene sheets owing to their weak intersheet interactions. Herein, an interfacial enhancement strategy to construct multifunctional, superelastic, and lightweight 3D MXene architectures by bridging individual MXene sheets with polyimide macromolecules is developed. The resulting lightweight aerogel exhibits superelasticity with large reversible compressibility, excellent fatigue resistance (1000 cycles at 50% strain), 20% reversible stretchability, and high electrical conductivity of ≈4.0 S m−1. The outstanding mechanical flexibility and electrical conductivity make the aerogel promising for damping, microwave absorption coating, and flexible strain sensor. More interestingly, an exceptional microwave absorption performance with a maximum reflection loss of −45.4 dB at 9.59 GHz and a wide effective absorption bandwidth of 5.1 GHz are achieved.
A 3D, electrically conductive, mechanically strong, and flexible MXene‐based aerogel reinforced with polyimide is fabricated for the first time. The conductive MXene/polyimide aerogel shows superelasticity, excellent resistance to fatigue for 1000 compression cycles under 50% strain, and thermal stability and fire retardancy, demonstrating its potential applications as multifunctional strain sensors and high‐performance microwave absorption coatings.
Porous Pt-based nanostructured materials possess intriguing physical and chemical properties to generate promising potential for various important applications such as fuel cells, sensors, ...stimulation electrodes, mechanical actuators and catalysis. With the great advances in material science and nanotechnology, porous Pt-based nanomaterials with well-controlled composition, shape, and geometrical configuration have been rationally designed and fabricated. Importantly, their superior properties including unique pore structure, large specific surface area and excellent structural stability have fuelled up great interest to improve their current performance and to explore new applications. This tutorial review attempts to summarize the recent important progress towards the development of porous Pt-based nanostructured materials, with special emphasis on fabrication methods and advanced electrochemical applications, such as electrocatalysis and electrochemical sensors. The correlations between the composition and morphology of the catalysts and their catalytic properties are discussed based on some important and representative examples. Some key scientific issues and potential future directions of research in this field are also discussed.
This tutorial review summarizes the recent progress in porous Pt-based nanostructures, with special emphasis on synthesis methods and electrochemical applications.
Abstract
The brightest gamma-ray burst, GRB 221009A, has spurred numerous theoretical investigations, with particular attention paid to the origins of ultrahigh-energy TeV photons during the prompt ...phase. However, analyzing the mechanism of radiation of photons in the ∼MeV range has been difficult because the high flux causes pileup and saturation effects in most GRB detectors. In this Letter, we present systematic modeling of the time-resolved spectra of the GRB using unsaturated data obtained from the Fermi Gamma-ray Burst Monitor (precursor) and SATech-01/GECAM-C (main emission and flare). Our approach incorporates the synchrotron radiation model, which assumes an expanding emission region with relativistic speed and a global magnetic field that decays with radius, and successfully fits such a model to the observational data. Our results indicate that the spectra of the burst are fully in accordance with a synchrotron origin from relativistic electrons accelerated at a large emission radius. The lack of thermal emission in the prompt emission spectra supports a Poynting flux–dominated jet composition.
Abstract
Short-duration gamma-ray bursts (sGRBs) are commonly attributed to the mergers of double neutron stars (NSs) or the mergers of a neutron star with a black hole (BH). While the former ...scenario was confirmed by the event GW170817, the latter remains elusive. Here, we consider the latter scenario in which an NS is tidally disrupted by a fast-spinning low-mass BH and the accretion onto the BH launches a relativistic jet and hence produces an sGRB. The merging binary’s orbit is likely misaligned with the BH’s spin. Hence, the Lense–Thirring precession around the BH may cause a hyperaccreting thick disk to precess in a solid-body manner. We propose that a jet, initially aligned with the BH spin, is deflected and collimated by the wind from the disk, therefore being forced to precess along with the disk. This would result in a quasiperiodic oscillation or modulation in the gamma-ray light curve of the sGRB, with a quasi-period of ∼0.01–0.1 s. The appearance of the modulation may be delayed respective to the triggering of the light curve. This feature, unique to the BH–NS merger, may have already revealed itself in a few observed sGRBs (such as GRB 130310A), and it carries the spin–orbit orientation information of the merging system. Identification of this feature would be a new approach to reveal spin–orbit misaligned merging BH–NS systems, which are likely missed by the current gravitational-wave searching strategy that is principally targeting aligned systems.
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