Observation of parabolic electron bands on superconductor LaRu_(2)As_(2)

Ru-based superconductor LaRu_(2)As_(2) has been discovered exhibiting the highest critical temperature of ~ 7.8 K among iron-free transition metal pnictides with the ThCr_(2)Si_(2)-type crystal structure. However, microscopic research on this novel superconducting material is still lacking. Here, we utilize scanning tunneling microscopy/spectroscopy to uncover the superconductivity and surface structure of LaRu_(2)As_(2). Two distinct terminating surfaces are identified on the cleaved crystals, namely, the As surface and the La surface. Atomic missing line defects are observed on the La surface. Both surfaces exhibit a superconducting gap of ~ 1.0 me V. By employing quasiparticle interference techniques, we observe standing wave patterns near the line defects on the La atomic plane. These patterns are attributed to quasiparticle scattering from two electron type parabolic bands.

Magnetic proximity effect in the two-dimensional ε-Fe_(2)O_(3)/NbSe_(2)heterojunction

Two-dimensional(2D)magnet/superconductor heterostructures can promote the design of artificial materials for exploring 2D physics and device applications by exotic proximity effects.However,plagued by the low Curie temperature and instability in air,it is hard to realize practical applications for the reported layered magnetic materials at present.In this paper,we developed a space-confined chemical vapor deposition method to synthesize ultrathin air-stable ε-Fe_(2)O_(3) nanosheets with Curie temperature above 350 K.The ε-Fe_(2)O_(3)/NbSe_(2) heterojunction was constructed to study the magnetic proximity effect on the superconductivity of the NbSe_(2) multilayer.The electrical transport results show that the subtle proximity effect can modulate the interfacial spin–orbit interaction while undegrading the superconducting critical parameters.Our work paves the way to construct 2D heterojunctions with ultrathin nonlayered materials and layered van der Waals(vdW)materials for exploring new physical phenomena.

Enhanced resonance frequency in Co2FeAl thin film with different thicknesses grown on flexible graphene substrate

The flexible materials exhibit more favorable properties than most rigid substrates in flexibility,weight saving,mechanical reliability,and excellent environmental toughness.Particularly,flexible graphene film with unique mechanical properties was extensively explored in high frequency devices.Herein,we report the characteristics of structure and magnetic properties at high frequency of Co2FeAl thin film with different thicknesses grown on flexible graphene substrate at room temperature.The exciting finding for the columnar structure of Co2FeAl thin film lays the foundation for excellent high frequency property of Co2FeAl/flexible graphene structure.In-plane magnetic anisotropy field varying with increasing thickness of Co2FeAl thin film can be obtained by measurement of ferromagnetic resonance,which can be ascribed to the enhancement of crystallinity and the increase of grain size.Meanwhile,the resonance frequency which can be achieved by the measurement of vector network analyzer with the microstrip method increases with increasing thickness of Co2FeAl thin film.Moreover,in our case with graphene film,the resonance magnetic field is quite stable though folded for twenty cycles,which demonstrates that good flexibility of graphene film and the stability of high frequency magnetic property of Co2FeAl thin film grown on flexible graphene substrate.These results are promising for the design of microwave devices and wireless communication equipment.

晚期上皮性卵巢癌初始治疗相关预测手段研究进展

上皮性卵巢癌(卵巢癌)以初始肿瘤细胞减灭术作为首选治疗方案,并得到指南的优先推荐,对于某些晚期患者,新辅助化疗的疗效亦得到肯定,但其适应证仍存在主观上的不同认知。因此,迫切需要客观预测手段指导优化病例的选择,使治疗达到风险与获益的统一。本文将就晚期卵巢癌初始治疗及预后相关预测手段进行综述,为临床实践提供参考。

Unidirectional plasmonic Bragg reflector based on longitudinally asymmetric nanostructures

Plasmonic Bragg reflectors are essential components in plasmonic circuits.Here we propose a novel type of plasmonic Bragg reflector, which has very high reflectance for the right-side incidence and meanwhile has extremely large absorption for the left-side incidence.This device is composed of longitudinally asymmetric nanostructures in a metal–insulator–metal waveguide.In order to efficiently analyze, design, and optimize the reflection and transmission characteristics of the proposed device, we develop a semi-analytic coupled-mode model.Results show that the reflectance extinction ratio between plasmonic modes incident from the right-side and the left-side reaches 11 dB.We expect this device with such striking unidirectional reflection performance can be used as insulators in nanoplasmonic circuits.

高质量PtP_(2)晶体中的三维弱局域化和负磁阻效应

近年来,含有五元环排列结构的PtP_(2)单晶和二维材料因具有丰富的物理和化学性能而得到广泛关注,有望应用于高性能电子和光电子器件.本文通过优化Pt和P的初始摩尔比,采用助溶剂法制备了高质量的PtP_(2)单晶,并在PtP_(2)单晶中首次发现了三维弱局域化和负磁阻效应.晶体结构、磁性和光谱测试表明,PtP_(2)单晶中的少量缺陷可抑制负磁阻效应和磁有序态.本文提出了合成高质量贵金属磷化物单晶的有效方法,为研究磷化物中多种关联电子态提供了新的平台.

Tunable ultrathin dual-phase P-doped Bi_(2)MoO_(6) nanosheets for advanced lithium and sodium storage

The construction of electrode materials for lithium-ion batteries(LIBs)and sodium-ion batteries(SIBs)has gradually been an appealing and attractive technology in energy storage research field.In the present work,a facile strategy of synthesizing ultrathin amorphous/nanocrystal dual-phase P-doped Bi_(2)MoO_(6)(denoted as P-BiMO)nanosheets via a one-step wet-chemical synthesis approach is explored.Quite distinct from conventional two-dimensional(2D)nanosheets,our newly developed ultrathin P-BiMO nanosheets exhibit a unique tunable amorphous/nanocrystalline dual-phase structure with several compelling advantages including fast ion exchange ability and superb volume change buffer capability.The experimental results reveal that our prepared P-BiMO-6 electrode delivers an excellent reversible capacity of 509.6 mA·g^(−1) after continuous 1,500 cycles at the current densities of 1,500 mA·g^(−1) and improved rate performance for LIBs.In the meanwhile,the P-BiMO-6 electrode also shows a reversible capacity of 300.6 mA·g^(−1) after 100 cycles at 50 mA·g^(−1) when being used as the SIBs electrodes.This present work uncovers an effective dual-phase nanosheet structure to improve the performance of batteries,providing an attractive paradigm to develop superior electrode materials.

Nacre-liked material with tough and post-tunable mechanical properties

Biomaterials,often imparted time-dependent mechanical properties,which are promising in fields rang-ing from sensors to robotics.Here,a facile method was proposed to fabricate post-tunable mechanical properties composites based on hydrogels and ceramic nanofiller.The wide tunable range of Young’s modulus(27.3 kPa to 3.5 GPa)and ultimate stress(173 kPa to 102 MPa)can be achieved by combining solvent absorption and evaporation process with platelets reinforcement effect.Additionally,a large fracture toughness(∼32,000 J m^(-2))is obtained as a result of the nacre-liked“brick and mortar”structure introduced by shear force during fabrication.The superior flexibility and designability of this material were demonstrated via actuators,portable structure,and metamaterials.Above all,this study provides a new thought to fabricate tough materials with post-tunable mechanical properties.

Comparison of modified injection molding and conventional machining in biodegradable behavior of perforated cannulated magnesium hip stents

In this study,perforated cannulated magnesium(Mg)hip stents were fabricated via modified Mg injection molding and conventional machining,respectively.Additionally,the stent canal was filled with paraffin to simulate injection of biomaterials.The microstructure,mechanical performance,corrosion behavior,and biocompatibility were comparably studied.Scanning electron microscopy(SEM)and energy dispersive spectroscopy(EDS)showed higher affinity of interstitial element such as oxygen and carbon as consequences of routine molding process.After immersion in SBF,machining stents showed reduced degradation rate and increased deposition of calcium phosphate compared to molding stents.Corrosion resistance was improved via paraffin-filling.Consistently,the hemolysis and in vitro osteoblast cell culture models showed favourable biocompatibility in machining stents compared to molding ones,which was improved by paraffin-filling treatment as well.These results implied that the feasibility of the prepared machining stents as the potential in vivo orthopaedic application where slower degradation is required,which could be enhanced by designing canal-filling injection of biomaterials as well.