Perovskite X‐ray detectors have been demonstrated to be sensitive to soft X‐rays (<80 keV) for potential medical imaging applications. However, developing X‐ray detectors that are stable and ...sensitive to hard X‐rays (80 to 120 keV) for practical medical imaging is highly desired. Here, a sensitive 2D fluorophenethylammonium lead iodide ((F‐PEA)2PbI4) perovskite single‐crystal hard‐X‐ray detector from low‐cost solution processes is reported. Dipole interaction of organic ions promotes the ordering of benzene rings as well as the supramolecular electrostatic interaction between electron‐deficient F atoms with neighbor benzene rings. Supramolecular interactions serve as a supramolecular anchor to stabilize and tune the electronic properties of single crystals. The 2D (F‐PEA)2PbI4 perovskite single crystal exhibits an intrinsic property with record bulk resistivity of 1.36 × 1012 Ω cm, which brings a low device noise for hard X‐ray detection. Meanwhile, the ion‐migration phenomenon is effectively suppressed, even under the large applied bias of 200 V, by blocking the ion migration paths after anchoring. Consequently, the (F‐PEA)2PbI4 single crystal detector yields a sensitivity of 3402 μC Gy−1air cm−2 to 120 keVp hard X‐rays with lowest detectable X‐ray dose rate of 23 nGyair s−1, outperforming the dominating CsI scintillator of commercial digital radiography systems by acquiring clear X‐ray images under much lower dose rate. In addition, the detector shows high operation stability under extremely high‐flux X‐ray irradiation.
F atoms in an organic spacer of a 2D perovskite enhance the supramolecular electrostatic interactions, serving as supramolecular anchors to stabilize single crystals. The corresponding optoelectronic properties are also improved. A fluorophenethylammonium lead iodide X‐ray detector exhibits stable and sensitive response to 120 keVp X‐rays; clear X‐ray images with detection limit of 23 nGy s−1 are demonstrated.
A sufficiently large supercurrent can close the energy gap in a superconductor and create gapless quasiparticles through the Doppler shift of quasiparticle energy caused by finite Cooper pair ...momentum. In this gapless superconducting state, zero-energy quasiparticles reside on a segment of the normal-state Fermi surface, whereas the remaining Fermi surface is still gapped. We use quasiparticle interference to image the field-controlled Fermi surface of bismuth telluride (Bi
Te
) thin films under proximity effect from the superconductor niobium diselenide (NbSe
). A small applied in-plane magnetic field induces a screening supercurrent, which leads to finite-momentum pairing on the topological surface states of Bi
Te
. We identify distinct interference patterns that indicate a gapless superconducting state with a segmented Fermi surface. Our results reveal the strong impact of finite Cooper pair momentum on the quasiparticle spectrum.
SnSe is a promising thermoelectric material with record-breaking figure of merit. However, to date a comprehensive understanding of the electronic structure and most critically, the self-hole-doping ...mechanism in SnSe is still absent. Here we report the highly anisotropic electronic structure of SnSe investigated by angle-resolved photoemission spectroscopy, in which a unique pudding-mould-shaped valence band with quasi-linear energy dispersion is revealed. We prove that p-type doping in SnSe is extrinsically controlled by local phase segregation of SnSe
microdomains via interfacial charge transferring. The multivalley nature of the pudding-mould band is manifested in quantum transport by crystallographic axis-dependent weak localisation and exotic non-saturating negative magnetoresistance. Strikingly, quantum oscillations also reveal 3D Fermi surface with unusual interlayer coupling strength in p-SnSe, in which individual monolayers are interwoven by peculiar point dislocation defects. Our results suggest that defect engineering may provide versatile routes in improving the thermoelectric performance of the SnSe family.
The exploration of topological superconductivity and Majorana zero modes has become a rapidly developing field. Many types of proposals to realize topological superconductors have been presented, and ...significant advances have been recently made. In this review, a survey is conducted on the experimental progress in possible topological superconductors and induced superconductivity in topological insulators or semimetals as well as artificial structures. The approaches to inducing superconductivity in topological materials mainly include high pressure application, the hard‐tip point contact method, chemical doping or intercalation, the use of artificial topological superconductors, and electric field gating. The evidence supporting topological superconductivity and signatures of Majorana zero modes are also discussed and summarized.
The exploration of topological superconductivity has become a rapidly developing field. Here, a survey is conducted on the experimental progress in exploring possible topological superconductivity in topological materials and artificial structures through the means of high pressure application, chemical doping or intercalation, and the use of artificial heterostructures, etc.
Realizing both ultralow breakdown voltage and ultrahigh gain is one of the major challenges in the development of high‐performance avalanche photodetector. Here, it is reported that an ultrahigh ...avalanche gain of 3 × 105 can be realized in the graphite/InSe Schottky photodetector at a breakdown voltage down to 5.5 V. Remarkably, the threshold breakdown voltage can be further reduced down to 1.8 V by raising the operating temperature, approaching the theoretical limit of 1.5 Eg\{{\cal E}_{\bf g}}\/e, with Eg${{\cal E}_{\bf g}}$ the bandgap of semiconductor. A 2D impact ionization model is developed and it is uncovered that observation of high gain at low breakdown voltage arises from reduced dimensionality of electron–phonon scattering in the layered InSe flake. These findings open up a promising avenue for developing novel weak‐light detectors with low energy consumption and high sensitivity.
Intrinsic threshold breakdown voltage with an ultrahigh gain is observed in an avalanche photodetector (APD) based on a graphite/InSe Schottky junction, which is attributed to the high ionization rate due to the reduced dimensionality of electron–phonon scattering in layered InSe. This work opens up a new avenue for future APDs with both low energy consumption and high sensitivity.
The ultimate goal of phototherapy based on nanoparticles, such as photothermal therapy (PTT) which generates heat and photodynamic therapy (PDT) which not only generates reactive oxygen species (ROS) ...but also induces a variety of anti-tumor immunity, is to kill tumors. In addition, due to strong efficacy in clinical treatment with minimal invasion and negligible side effects, it has received extensive attention and research in recent years. In this paper, the generations of nanomaterials in PTT and PDT are described separately. In clinical application, according to the different combination pathway of nanoparticles, it can be used to treat different diseases such as tumors, melanoma, rheumatoid and so on. In this paper, the mechanism of pathological treatment is described in detail in terms of inducing apoptosis of cancer cells by ROS produced by PDT, immunogenic cell death to provoke the maturation of dendritic cells, which in turn activate production of CD4+ T cells, CD8+T cells and memory T cells, as well as inhibiting heat shock protein (HSPs), STAT3 signal pathway and so on.
The long‐range magnetic ordering in frustrated magnetic systems is stabilized by coupling magnetic moments to various degrees of freedom, for example, by enhancing magnetic anisotropy via lattice ...distortion. Here, the unconventional spin‐lattice coupled metamagnetic properties of atomically‐thin CrOCl, a van der Waals antiferromagnet with inherent magnetic frustration rooted in the staggered square lattice, are reported. Using temperature‐ and angle‐dependent tunneling magnetoconductance (TMC), in complementary with magnetic torque and first‐principles calculations, the antiferromagnetic (AFM)‐to‐ferrimagnetic (FiM) metamagnetic transitions (MTs) of few‐layer CrOCl are revealed to be triggered by collective magnetic moment flipping rather than the established spin‐flop mechanism, when external magnetic field (H) enforces a lattice reconstruction interlocked with the five‐fold periodicity of the FiM phase. The spin‐lattice coupled MTs are manifested by drastic jumps in TMC, which show anomalous upshifts at the transition thresholds and persist much higher above the AFM Néel temperature. While the MTs exhibit distinctive triaxial anisotropy, reflecting divergent magnetocrystalline anisotropy of the c‐axis AFM ground state, the resulting FiM phase has an a‐c easy plane in which the magnetization axis is freely rotated by H. At the 2D limit, such a field‐tunable FiM phase may provide unique opportunities to explore exotic emergent phenomena and novel spintronics devices.
Distinct from the established spin‐flop type metamagnetism, this work reports the unconventional spin‐lattice interlocked metamagnetism in few‐layer CrOCl down to the monolayer thickness. These unconventional metamagnetic transitions produce a unique field‐tunable ferrimagnetic phase with the magnetization axis freely rotated by magnetic field within an easy plane.
The Global Entrepreneurship and Development Institute (GEDI) annually releases the Global Entrepreneurship Index (GEI) to measure the quality and dynamics of entrepreneurship ecosystems at a national ...and regional level. The published Global Entrepreneurship Index takes the arithmetic mean value of the individual level of entrepreneurial attitudes, abilities and aspirations. In this paper, we alternatively consider all individual preferences among these three sub-indices, the performance results of which are obtained by means of a sophisticated manner. The entropy values of these performance results are derived to reduce the information redundancy. The best-worst method (BWM) is employed to determine the common weights with respect to each individual preference. An empirical study using the data of GEI-2019 is performed to indicate the validness of our methodology.
Independent origins of carnivory in multiple angiosperm families are fabulous examples of convergent evolution using a diverse array of life forms and habitats. Previous studies have indicated that ...carnivorous plants have distinct evolutionary trajectories of plastid genome (plastome) compared to their non-carnivorous relatives, yet the extent and general characteristics remain elusive.
We compared plastomes from 9 out of 13 carnivorous families and their non-carnivorous relatives to assess carnivory-associated evolutionary patterns. We identified inversions in all sampled Droseraceae species and four species of Utricularia, Pinguicula, Darlingtonia and Triphyophyllum. A few carnivores showed distinct shifts in inverted repeat boundaries and the overall repeat contents. Many ndh genes, along with some other genes, were independently lost in several carnivorous lineages. We detected significant substitution rate variations in most sampled carnivorous lineages. A significant overall substitution rate acceleration characterizes the two largest carnivorous lineages of Droseraceae and Lentibulariaceae. We also observe moderate substitution rates acceleration in many genes of Cephalotus follicularis, Roridula gorgonias, and Drosophyllum lusitanicum. However, only a few genes exhibit significant relaxed selection.
Our results indicate that the carnivory of plants have different effects on plastome evolution across carnivorous lineages. The complex mechanism under carnivorous habitats may have resulted in distinctive plastome evolution with conserved plastome in the Brocchinia hechtioides to strongly reconfigured plastomes structures in Droseraceae. Organic carbon obtained from prey and the efficiency of utilizing prey-derived nutrients might constitute possible explanation.
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