Single‐atom catalysts (SACs) have garnered enormous interest due to their remarkable catalysis activity. However, the exploitation of universal synthesis strategy and regulation of coordination ...environment of SACs remain a great challenge. Herein, a versatile synthetic strategy is demonstrated to generate a series of transition metal SACs (M SAs/NC, M = Co, Cu, Mn; NC represents the nitrogen‐doped carbon) through defect engineering of metal‐organic frameworks (MOFs). The interatomic distance between metal sites can be increased by deliberately introducing structural defects within the MOF framework, which inhibits metal aggregation and consequently results in an approximately 70% increase in single metal atom yield. Additionally, the coordination structures of metal sites can also be facilely tuned. The optimized Co SAs/NC‐800 exhibits superior activity and excellent reusability for the selective hydrogenation of nitroarenes, surpassing several state‐of‐art non‐noble‐metal catalysts. This study provides a new avenue for the universal fabrication of transition metal SACs.
A general metal–organic framework defect engineering strategy is proposed to increase the yield of single‐atom catalysts. This strategy enlarges the distance between metal active sites, effectively hindering the aggregation of metal atoms and affording a 70% improved yield of metal single atoms. The optimized Co SAs/NC‐800 exhibits superior activity and reusability in nitroarene hydrogenation.
The chemical diversity and structural flexibility of lead halide perovskites (LHPs) offer tremendous opportunities to tune their optical properties through internal molecular engineering and external ...stimuli. Herein, we report the wide‐range and ultrapure photoluminescence emissions in a family of homologous 2D LHPs, MeOPEA2PbBr4−4xI4x (MeOPEA=4‐methoxyphenethylammonium; x=0, 0.2, 0.425, 0.575, 1) enabled through internal chemical pressure and external hydrostatic pressure. The chemical pressure, induced by the C−H⋅⋅⋅π interactions and halogen doping/substitution strengthens the structural rigidity to give sustained narrow emissions, and regulates the emission energy, respectively. Further manipulation of physical pressure leads to wide‐range emission tuning from 412 to 647 nm in a continuous and reversible manner. This work could open up new pathways for developing 2D LHP emitters with ultra‐wide color gamut and high color purity which are highly useful for pressure sensing.
Wide‐range and ultrapure emissions are achieved in 2D lead halide perovskites (LHPs) by combined chemical pressure from halogen doping/substitution and physical pressure from hydrostatic compression. This work demonstrates precise emission tuning and effective color regulation of 2D LHPs by pressure engineering, which would open a new pathway for developing ultrapure emitters and highly sensitive pressure sensors.
Hybrid organic–inorganic piezoelectrics have attracted attention due to their simple synthesis, mechanical flexibility, and designability, which have promising application potential in flexible ...sensing and self‐powered energy harvesting devices. Although some hybrid piezoelectrics are discovered, most of their structures are limited by the perovskite‐type and often contain lead. Herein, the synthesis, structure, and piezoelectric properties of a new hybrid lead‐free metal halide, (BTMA)2CoBr4 (BTMA = benzyltrimethylammonium) are reported. The experimental and theoretical results demonstrate that this material simply composed of CoBr42− tetrahedra and BTMA+ cations exhibits significant piezoelectricity (d22 = 5.14, d25 = 12.40 pC N−1), low Young's and shear moduli (4.11–17.56 GPa; 1.86–7.91 GPa). Moreover, the (BTMA)2CoBr4/PDMS (PDMS = polydimethylsiloxane) composite thin films are fabricated and optimized. The 10% (BTMA)2CoBr4/PDMS‐based flexible devices show attractive performance in energy harvesting with an open‐circuit voltage of 19.70 V, short‐circuit current of 4.24 µA, and powder density of 11.72 µW cm−2, catching up with those of piezoelectric ceramic composites. Meanwhile, these film devices show excellent capability in accurately sensing human body motions, such as finger bending and tapping. This work demonstrates that (BTMA)2CoBr4 and related piezoelectric lead‐free halides can be promising molecular materials in modern energy and sensing applications.
A hybrid lead‐free metal halide, (BTMA)2CoBr4 (BTMA, benzyltrimethylammonium), is demonstrated to exhibit significant piezoelectricity and soft elastic properties. Moreover, (BTMA)2CoBr4‐based composite films are fabricated for energy harvesting and human body motion sensing with attractive performance. This work broadens the landscape of molecular piezoelectric materials by paying more attention to the non‐perovskite‐type and lead‐free hybrid organic‐inorganic systems.
The structural reconstruction at the crystal layer edges of 2D lead halide perovskites (LHPs) leads to unique edge states (ES), which are manifested by prolonged carrier lifetime and reduced emission ...energy. These special ES can effectively enhance the optoelectronic performance of devices, but their intrinsic origin and working mechanism remain elusive. Here it is demonstrated that the ES of a family of 2D Ruddlesden–Popper LHPs BA2CsPb2Br7, BA2MAPb2Br7, and BA2MA2Pb3Br10 (BA = butylammonium; MA = methylammonium) arise from the rotational symmetry elevation of the PbBr6 octahedra dangling at the crystal layer edges. These dangling octahedra give rise to localized electronic states that enable an effective transport of electrons from the interior to layer edges, and the population of electrons in both the interior states and the ES can be manipulated via controlling the external fields. Moreover, the abundant phonons, activated by the dangling octahedra, can interact with electrons to facilitate radiative recombination, counterintuitive to the suppressive role commonly observed in conventional semiconductors. This work unveils the intrinsic atomistic and electronic origins of ES in 2D LHPs, which can stimulate the exploration of ES‐based exotic optoelectronic properties and the corresponding design of high‐performance devices for these emergent low‐dimensional semiconductors.
The low‐energy and long‐lived edge states of 2D lead halide perovskites arise from the rotational symmetry elevation at the crystal layer edges, which are enabled by dangling PbBr6 octahedra at the lattice terminals. These dangling octahedra with enhanced atomic vibrations can give rise to localized electronic states that enable an effective electron transport from the interior to layer edges.
Pressure‐induced emission enhancement (PIEE) is a novel phenomenon in contrast to conventional pressure‐induced emission quenching, and has attracted considerable attention owing to the potential ...application of materials with this effect as optical pressure‐sensing devices. The urgent need and significant significance lie in the design and exploration of systems that possess high‐efficiency PIEE. Here, a large PIEE in a novel zero‐dimensional (0D) hybrid manganese bromide is realized, (BPPH)2MnBr4·1.5CH3CN BPPH+ = bis(triphenylphosphine)iminium. The experimental and theoretical results demonstrate that such emission enhancement is primarily attributed to the pressure‐induced reconfiguration of electronic band alignment and resultant redistribution of band‐edge excitons. Under compression, the electronic bandgap of (MnBr4)2− experiences a more rapid reduction compared to that of the organic cations. Consequently, this leads to the gradual closure of the charge transfer pathway from (MnBr4)2− to BPPH+. This progression results in a higher retention of excitons on (MnBr4)2−, amplifying the efficiency of Mn2+ d–d transitions, and leading to a substantial enhancement in emission. This study not only offers fresh insights into the behavior of carrier dynamics induced by pressure in hybrid manganese halides but also presents a promising avenue for the advancement of PIEE systems.
Significant emission enhancement is achieved in a hybrid manganese bromide via pressure‐induced band‐edge carrier reconfiguration. This study not only offers fresh insights into the behavior of carrier dynamics induced by pressure in hybrid manganese halides but also presents a promising avenue for the advancement of pressure‐induced emission enhancement systems.
Managing elastic properties of ABX3 type molecular perovskite ferroelectrics is critical to their future applications since these parameters determine their service durability and reliability in ...devices. The abundant structural and chemical viability of these compounds offer a convenient way to manipulate their elastic properties through a facile chemical approach. Here, the elastic properties and high‐pressure behaviors of two isostructural perovskite ferroelectrics, MDABCO‐NH4I3 and MDABCO‐KI3 (MDABCO = N‐methyl‐N′‐diazabicyclo2.2.2octonium) is systematically investigated, via the first principles calculations and high‐pressure synchrotron X‐ray diffraction experiments. It is show that the simple replacement of NH4+ by K+ on the B‐site respectively results in up to 48.1%, 52.4%, and 56.3% higher Young's moduli, shear moduli and bulk moduli, which is attributed to the much stronger KI coordination bonding than NH4…I hydrogen bonding. These findings demonstrate that it is possible to tune elastic properties of molecular perovskite ferroelectrics via simply varying the framework assembling interactions.
Elastic properties of two isostructural molecular perovskite ferroelectrics are systematically investigated. Strikingly, MDABCO‐KI3 shows much higher moduli than those of MDABCO‐NH4I3 due to the marked different strengths between KI coordination bonds and NH4…I hydrogen interactions. This work demonstrates that it is possible to manage elastic properties of molecular ferroelectrics via facile chemical substitution.
Summary
Frequent germline mutations of HAVCR2, recently identified in subcutaneous panniculitis‐like T‐cell lymphoma (SPTCL), are associated with an increased risk of hemophagocytic ...lymphohistiocytosis (HLH). However, SPTCL‐HLH represents a challenge because of the difficulties in treatment with poor survival. Its malignant nature, specifically harbouring HAVCR2 mutations, has also been questioned. To better understand its pathology and treatment, we analysed the clinical data of six patients diagnosed at our centre. The median age at onset was 10.5 years (range, 0.8–12.4). Five patients presented with skin lesions of subcutaneous nodules/plaques and/or ulceration. All patients developed HLH; notably, one infant only had HLH without skin involvement. Histopathologically, only two patients were diagnosed with SPTCL and three were reported as panniculitis with no sufficient evidence of lymphoma. Genetically, germline homozygous mutation of HAVCR2 (p.Y82C) was identified in all patients, with a median diagnosis time of 4.6 months. All patients initially received corticosteroids, immunosuppressants or chemotherapy, achieving unfavourable responses. Strikingly, they responded well to ruxolitinib targeting inflammatory cytokines, allowing rapid disease resolution and/or long‐term maintenance of remission. The excellent efficacy of ruxolitinib highlights this disease as an inflammatory condition instead of neoplastic nature and indicates novel agents targeting key inflammatory pathways as an encouraging approach for this disease entity.
Evidential reasoning (ER) rule has been widely used in the fields of information fusion, multiattribute decision making, and pattern recognition. In current studies of ER rule, there is a strict ...one-to-one correspondence between the framework of discernment (FoD) of evidence and the FoD of reasoning results. However, this may not be satisfied in engineering practice, making it difficult to conduct the reasoning. When the element of FoD is changed, how the reasoning result will change is also a focus that deserves attention. As such, in this article, the modeling, optimization, and robustness analysis method of ER rule under multidiscernment framework is proposed. Specifically, the ER rule with transformation matrix is proposed to unify the evidence with different FoDs into the same FoD as reasoning results. A parameter optimization model is established based on the expected utility and interpretable constraints. A robustness analysis method of the proposed ER rule is proposed in the context of perturbation to further explore its performance. Particularly, the generation and transmission rules of perturbation are described, and two robustness criteria are defined. A case study of health assessment of laser gyroscope, the mainstream navigation equipment in the aerospace field, is conducted to present the implementation of the proposed method and verify its effectiveness in engineering practice.
Abstract 2D conductive metal–organic frameworks (2D c ‐MOFs) have attracted increasing attention as promising electrode materials for rechargeable batteries due to their designable periodic motifs, ...large specific surface areas, and prominent electrical conductivity. However, the development of 2D c ‐MOF electrode materials with functionality remains a significant challenge because of the limited electroactive ligand motifs available. Herein, a hexahydroxy‐substituted triazacoronene ligand (6OH‐TAC) is deliberately designed and synthesized, which coordinates with Cu 2+ ions to form an unprecedented 2D c ‐MOF (Cu‐TAC) with functionality sites of efficient lithium storage. The synergistic effect of TAC and CuO 4 enables Cu‐TAC as an anode for lithium‐ion batteries with a superior reversible capacity of 772.4 mAh g −1 at 300 mA g −1 , remarkable rate performance, and outstanding long‐term cyclability (83% capacity retention at 300 mA g −1 for 600 cycles). These metrics outperform almost all 2D c ‐MOF‐based electrodes, shedding light on new opportunities for energy storage devices.
Acute lymphoblastic leukemia (ALL) is the most common malignancy among children. The trial Chinese Children Leukemia Group (CCLG)‐ALL 2008 was a prospective clinical trial designed to improve ...treatment outcome of childhood ALL through the first nation‐wide collaborative study in China. Totally 2231 patients were recruited from ten tertiary hospitals in eight cities. The patients were stratified according to clinical‐biological characteristics and early treatment response. Standard risk (SR) and intermediate risk (IR) groups were treated with a modified BFM based protocol, and there was 25%‐50% dose reduction during intensification phases in the SR group. Patients in high risk (HR) group received a more intensive maintenance treatment. Minimal residual disease (MRD) monitoring with treatment adjustment was performed in two hospitals (the MRD group). Complete remission (CR) was achieved in 2100 patients (94.1%). At five years, the estimate for overall survival (OS) and event‐free survival (EFS) of the whole group was 85.3% and 79.9%, respectively. The cumulative incidence of relapse (CIR) was 15.3% at five years. The OS, EFS and CIR for the SR group were 91.5%, 87.9%, and 9.7%, respectively. The outcome of the MRD group is better than the non‐MRD group (5y‐EFS: 82.4% vs 78.3%, P = .038; 5y‐CIR: 10.7% vs 18.0%, P < .001). Our results demonstrated that the large‐scale multicenter trial for pediatric ALL was feasible in China. Dose reduction in the SR group could achieve high EFS. MRD‐based risk stratification might improve the treatment outcome for childhood ALL.
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