Intermolecular Acid-Base-Pairs Containing Poly(p-Terphenyl-co-lsatin Piperidinium)for High Temperature Proton Exchange Membrane Fuel Cells

How to optimize and regulate the distribution of phosphoric acid in matrix,and pursuing the improved electrochemical performance and service lifetime of high temperature proton exchange membrane(HT-PEMs)fuel cell are significant challenges.Herein,bifunctional poly(p-terphenyl-co-isatin piperidinium)copolymer with tethered phosphonic acid(t-PA)and intrinsic tertiary amine base groups are firstly prepared and investigated as HT-PEMs.The distinctive architecture of the copolymer provides a well-designed platform for rapid proton transport.Protons not only transports through the hydrogen bond network formed by the adsorbed free phosphoric acid(f-PA)anchored by the tertiary amine base groups,but also rely upon the proton channel constructed by the ionic cluster formed by the t-PA aggregation.Thorough the design of the structure,the bifunctional copolymers with lower PA uptake level(<100%)display prominent proton conductivities and peak power densities(99 mS cm^(-1),812 mW cm^(-2)at 160℃),along with lower PA leaching and higher voltage stability,which is a top leading result in disclosed literature.The results demonstrate that the design of intermolecular acid-base-pairs can improve the proton conductivity without sacrificing the intrinsic chemical stability or mechanical property of the thin membrane,realizing win-win demands between the mechanical robustness and electrochemical properties of HT-PEMs.

Epitaxial growth of trilayer graphene moiré superlattice

The graphene-based moiré superlattice has been demonstrated as an exciting system for investigating strong correlation phenomenon. However, the fabrication of such moiré superlattice mainly relies on transfer technology. Here, we report the epitaxial growth of trilayer graphene(TLG) moiré superlattice on hexagonal boron nitride(h BN) by a remote plasma-enhanced chemical vapor deposition method. The as-grown TLG/h BN shows a uniform moiré pattern with a period of ~ 15 nm by atomic force microscopy(AFM) imaging, which agrees with the lattice mismatch between graphene and h BN. By fabricating the device with both top and bottom gates, we observed a gate-tunable bandgap at charge neutral point(CNP) and displacement field tunable satellite resistance peaks at half and full fillings. The resistance peak at half-filling indicates a strong electron–electron correlation in our grown TLG/h BN superlattice. In addition, we observed quantum Hall states at Landau level filling factors ν = 6, 10, 14,..., indicating that our grown trilayer graphene has the ABC stacking order. Our work suggests that epitaxy provides an easy way to fabricate stable and reproducible two-dimensional strongly correlated electronic materials.

Coupled Ferroelectricity and Correlated States in a Twisted Quadrilayer MoS_(2) Moiré Superlattice

Moiré superlattices have emerged as a highly controllable quantum platform for exploration of various fascinating phenomena,such as Mott insulator states,ferroelectric order,unconventional superconductivity and orbital ferromagnetism.Although remarkable progress has been achieved,current research in moiré physics has mainly focused on the single species properties,while the coupling between distinct moiré quantum phenomena remains elusive.Here we demonstrate,for the first time,the strong coupling between ferroelectricity and correlated states in a twisted quadrilayer MoS2moiré superlattice,where the twist angles are controlled in sequence to be ~57°,~0°,and ~-57°.Correlated insulator states are unambiguously established at moiré band filling factors v = 1,2,3 of twisted quadrilayer MoS_(2).Remarkably,ferroelectric order can occur at correlated insulator states and disappears quickly as the moiré band filling deviates from the integer fillings,providing smoking gun evidences of the coupling between ferroelectricity and correlated states.Our results demonstrate the coupling between different moiré quantum properties and will hold great promise for new moiré physics and applications.

Precisely controlling the twist angle of epitaxial MoS_(2)/graphene heterostructure by AFM tip manipulation

Two-dimensional(2D)moirématerials have attracted a lot of attention and opened a new research frontier of twistronics due to their novel physical properties.Although great progress has been achieved,the inability to precisely and reproducibly manipulate the twist angle hinders the further development of twistronics.Here,we demonstrated an atomic force microscope(AFM)tip manipulation method to control the interlayer twist angle of epitaxial MoS_(2)/graphene heterostructure with an ultra-high accuracy better than 0.1°.Furthermore,conductive AFM and spectroscopic characterizations were conducted to show the effects of the twist angle on moirépattern wavelength,phonons and excitons.Our work provides a technique to precisely control the twist angle of 2D moirématerials,enabling the possibility to establish the phase diagrams of moiréphysics with twist angle.

Virilizing Ovarian Leydig Cell Tumor with Multiple Non-Functional Endocrine Neoplasias: A Case Report

Ovarian Leydig cell tumor, a sub-type of ovarian steroid cell tumor, accounts for less than 0.1% of all ovarian tumors. It can affect women of any age group but is most common in postmenopausal women. We here report a case of virilizing ovarian Leydig cell tumor with multiple non-functional endocrine neoplasias (pituitary and adrenal adenomas) in a 48-year-old woman. She first presented with sub-abdominal pain and hirsutism since menopause three years ago. Subsequently, she had slight facial acne, voice deepening, breast atrophy, and a prominent Adam’s apple. Her hormone profile showed an elevated level of testosterone, high free androgen index, low levels of luteinizing hormone and follicle stimulating hormone, and normal levels of random cortisol, androstenedione, 17-hydroxyprogesterone and dehydroepiandrosterone sulfate. A pelvic enhanced magnetic resonance imaging (MRI) scan showed nodules in the right ovary, and a pituitary enhanced MRI revealed a microadenoma. An enhanced computerized tomography scan of the adrenal gland revealed left adrenal nodules, possibly adenomas. After a right cystectomy and right fallopian tube resection, her testosterone level declined to 0.38 nmol/L and the symptoms associated with hyperandrogenism improved. This is a rare case of virilizing ovarian Leydig cell tumor with multiple non-functional endocrine neoplasias. We believe our findings will be helpful in the clinical diagnosis and treatment of hyperandrogenism.

A Perspective on Rhythmic Gymnastics Performance Analysis Powered by Intelligent Fabric

Performance analysis is an important tool for gymnasts and coaches to assess the techniques,strengths,and weaknesses of rhythmic gymnasts during training.To have an accurate insight about the motion and postures can help the optimization of their performance and offer personalized suggestions.However,there are three primary limitations of traditional perfor-mance analysis systems applied in rhythmic gymnastics:(1)Inability to quantify anthropometric data in an imperceptible way,(2)labor-intensive nature of data labeling and analysis,and(3)lack of monitoring of all-round and multi-dimensional perspectives of the target.Thus,an advanced performance analysis system for rhythmic gymnastics is proposed in this paper,powered by intelligent fabric.The system uses intelligent fabric to detect the physiological and anthropometric data of the gymnasts.After a variety of data are collected,the analysis component is implemented by artificial intelligence techniques resulting in behavior recognition,decision-making,and other functions assisting performance improvement.A feasible solution to implementing the analysis component is the use of the hyperdimensional computing technique.In addition,four typical applications are presented to improve training performance.Powered by intelligent fabric,the proposed advanced performance analysis system exhibits the potential to promote innovative technologies for improving training and competi-tive performance,prolonging athletic careers,as well as reducing sports injuries.

Real- and momentum-indirect neutral and charged excitons in a multi-valley semiconductor

Excitons dominate the photonic and optoelectronic properties of a material.Although significant advancements exist in understanding various types of excitons,progress on excitons that are indirect in both real-and momentum-spaces is still limited.Here,we demonstrate the real-and momentum-indirect neutral and charged excitons(including their phonon replicas)in a multi-valley semiconductor of bilayer MoS_(2),by performing electric-field/doping-density dependent photoluminescence.Together with first-principles calculations,we uncover that the observed real-and momentum-indirect exciton involves electron/hole from K/Γvalley,solving the longstanding controversy of its momentum origin.Remarkably,the binding energy of real-and momentum-indirect charged exciton is extremely large(i.e.,~59 meV),more than twice that of real-and momentum-direct charged exciton(i.e.,~24 meV).The giant binding energy,along with the electrical tunability and long lifetime,endows real-and momentum-indirect excitons an emerging platform to study many-body physics and to illuminate developments in photonics and optoelectronics.

Microstructure-based multiphysics modeling for semiconductor integration and packaging

Semiconductor technology and packaging is advancing rapidly toward system integration where the packaging is co-designed and co-manufactured along with the wafer fabrication.However,materials issues,in particular the mesoscale microstructure,have to date been excluded from the integrated product design cycle of electronic packaging due to the myriad of materials used and the complex nature of the material phenomena that require a multiphysics approach to describe.In the context of the materials genome initiative,we present an overview of a series of studies that aim to establish the linkages between the material microstructure and its responses by considering the multiple perspectives of the various multiphysics fields.The microstructure was predicted using thermodynamic calculations,sharp interface kinetic models,phase field,and phase field crystal modelingtechniques.Based on the predicted mesoscale microstructure,linear elastic mechanical analyses and electromigration simulations on the ultrafine interconnects were performed.The microstructural index extracted by a method based on singular value decomposition exhibits a monotonous decrease with an increase in the interconnect size.An artificial neural network-based fitting revealed a nonlinear relationship between the microstructure index and the average von Mises stress in the ultrafine interconnects.Future work to address the randomness of microstructure and the resulting scatter in the reliability is discussed in this study.

Transactive Energy Trading in Reconfigurable Multi-carrier Energy Systems

The penetration of multi-carrier energy systems in distribution system gains more and more concerns.In this paper,a bi-level transactive energy trading framework is proposed to improve the energy scheduling and operation efficiency for multi-carrier energy systems which are modeled as energy hubs(EHs).In the upper level,each EH in the distribution system not only makes energy scheduling decisions considering supplies and demands of local energy,but also trades energy with each other to further maximize their social welfare.The associated trading payment among EHs is made in a fair manner by applying Nash bargaining theory.We solve the bargaining problem by decomposing it into two subproblems:operation cost minimization problem and payment bargaining problem.Then,based on the trading decision,the nodal equivalent loads of EHs are sent to the distribution system operator(DSO)without publishing trading details.By applying the second-order cone programming(SOCP),DSO reconfigures the network to reduce the transmission loss of the system in the lower level.The network reconfiguration and the trading behavior of EHs interact and iterate until the convergence.Numerical studies on modified IEEE 33-bus distribution system demonstrate the effectiveness of the proposed framework.

A Familial Phenotypic and Genetic Study of Mutations in PFN1 Associated with Amyotrophic Lateral Sclerosis

Dear Editor,Amyotrophic lateral sclerosis(ALS)is a progressive and fatal neurodegenerative disease that prominently affects both upper and lower motor neurons.The prevalence of ALS has been estimated at 2.6-3.0 per 100,000 in Europe,5.2 per 100,000 in the USA,and 1.9-9.9 per 100,000 in Asia[1-3].ALS is classified as sporadic(sALS)or familial(fALS),but only 5%-10% of cases are identified as familial[4,5].

A new approach to maintaining the structural integrity of fragile nanostructured heterogeneous catalysts with nanoscale magnetic stir bars

Three-dimensional (3D) self-assembled nanomaterials with hierarchical architectures are very attractive materials due to their superior physical and chemical properties [1-7]. Over the past few years, a variety of nanomaterials with well-controlled structures were developed and applied in many areas, including water treatment, energy, sensor and catalysis [8-16].