Generalized Parity-Time Symmetry Condition for Enhanced Sensor Telemetry

Wireless sensors based on micro-machined tunable resonators are important in a variety of applications, ranging from medical diagnosis to industrial and environmental monitoring.The sensitivity of these devices is, however, often limited by their low quality (Q) factor.Here, we introduce the concept of isospectral party time reciprocal scaling (PTX) symmetry and show that it can be used to build a new family of radiofrequency wireless microsensors exhibiting ultrasensitive responses and ultrahigh resolution, which are well beyond the limitations of conventional passive sensors. We show theoretically, and demonstrate experimentally using microelectromechanical based wireless pressure sensors, that PTXsymmetric electronic systems share the same eigenfrequencies as their parity time (PT)-symmetric counterparts, but crucially have different circuit profiles and eigenmodes. This simplifies the electronic circuit design and enables further enhancements to the extrinsic Q factor of the sensors

Chemical vapor deposition and Van der Waals epitaxy for wafer-scale emerging 2D transition metal di-chalcogenides

Transition metal di-chalcogenides (TMDCs) such as MoS2, MoSe2, WS2 and WSe2 have become promising complimentary materials to graphene sharing many of its attributes. They may however offer properties that are unattainable in graphene, in particular TMDCs offer a bandgap tunable through both composition and number of layers. This has led to use of TMDCs in applications such as transistors, photodetectors, electroluminescent and bio-sensing devices. The current challenge in this emerging research field is to provide a reliable process to fabricate large area of atomically thin 2D TMDCs on the desired substrate. Chemical vapor deposition (CVD) technology has the advantage of offering conformal, scalable, and controllable thin film growth on a variety of different substrates. In addition, Van der Waals epitaxy could provide the vapor phase epitaxy of these TMDCs on the substrates with mismatched lattice constants. In this talk we describe our recent development in TMDCs materials using CVD technology and Van der Waals epitaxy and discuss their properties and potential applications

Emerging CVD technology for functional chalcogenide materials

Chalcogenide materials, formed from metallic alloys of S, Se, and Te, have received considerable attention for applications in optoelectronic devices over the past two decades in part due to their unique properties such as high infrared transparency, strong photosensitivity, large nonlinearity, capability of high rare-earth doping, and ability to readily change phase. Thin amorphous chalcogenide films are of particular interest because their diverse active properties are easily exploited in integrated planar optical circuits, as well as for memory and other optoelectronic applications. More recently, transition metal dichalcogenides (TMDCs), two-dimensional (2D) layered materials, such as MoS2, MoSe2, WS2, and WSe2 have become a noteworthy complimentary material to field. Sharing many of the properties of graphene they also offer properties that are unattainable in 2D graphene including a tunable bandgap; easily modified through both composition and the number of layers. This has led to use of TMDCs in applications such as transistors, photodetectors, electroluminescent and bio-sensing devices. In this talk we describe our development of functional chalcogenide materials by the chemical vapour deposition technology and discuss their potential applications

Synergy of cations in high entropy oxide lithium ion battery anode

High entropy oxides (HEOs) with chemically disordered multi-cation structure attract intensive interest as negative electrode materials for battery applications. The outstanding electrochemical performance has been attributed to the high-entropy stabilization and the so-called ‘cocktail effect’. However, the configurational entropy of the HEO, which is thermodynamically only metastable at room-temperature, is insufficient to drive the structural reversibility during conversion-type battery reaction, and the ‘cocktail effect’ has not been explained thus far. This work unveils the multi-cations synergy of the HEO Mg$_{0.2}$Co$_{0.2}$Ni$_{0.2}$Cu$_{0.2}$Zn$_{0.2}$O at atomic and nanoscale during electrochemical reaction and explains the ‘cocktail effect’. The more electronegative elements form an electrochemically inert 3-dimensional metallic nano-network enabling electron transport. The electrochemical inactive cation stabilizes an oxide nanophase, which is semi-coherent with the metallic phase and accommodates Li$^+$ ions. This self-assembled nanostructure enables stable cycling of micron-sized particles, which bypasses the need for nanoscale pre-modification required for conventional metal oxides in battery applications. This demonstrates elemental diversity is the key for optimizing multi-cation electrode materials

Proteogenomic characterization of endometrial carcinoma

We undertook a comprehensive proteogenomic characterization of 95 prospectively collected endometrial carcinomas, comprising 83 endometrioid and 12 serous tumors. This analysis revealed possible new consequences of perturbations to the p53 and Wnt/β-catenin pathways, identified a potential role for circRNAs in the epithelial-mesenchymal transition, and provided new information about proteomic markers of clinical and genomic tumor subgroups, including relationships to known druggable pathways. An extensive genome-wide acetylation survey yielded insights into regulatory mechanisms linking Wnt signaling and histone acetylation. We also characterized aspects of the tumor immune landscape, including immunogenic alterations, neoantigens, common cancer/testis antigens, and the immune microenvironment, all of which can inform immunotherapy decisions. Collectively, our multi-omic analyses provide a valuable resource for researchers and clinicians, identify new molecular associations of potential mechanistic significance in the development of endometrial cancers, and suggest novel approaches for identifying potential therapeutic targets

Mechanochemical synthesis of novel rutile-type high entropy fluorides for electrocatalysis

Multicomponent rutile (P4$_{2}$/mnm) structured fluorides, containing 4 to 7 transition metals (Co, Cu, Mg, Ni, Zn, Mn, and Fe) in equiatomic ratios, were synthesized using a simple mechanochemical approach. The high entropy fluorides were characterized using different techniques, all of which indicate that the high entropy fluorides tend to crystallize into a homogeneously mixed solid solution and single-phase structure. These high entropy fluorides represent an additional class of high entropy ceramics, which have recently attracted attention especially due to the development of high entropy oxides. With the introduction of these novel high entropy fluorides, similar interest could be generated due to the variety of different applications for fluoride materials and the improvements the high entropy concept might bring. Here we present an in-depth characterization study and the potential application of high entropy fluorides as a catalyst for the oxygen evolution reaction, in which the high entropy fluorides do show increased performance compared to a state-of-the-art catalyst for the oxygen evolution reaction, IrO$_{2}$, despite eliminating noble metal constituents

Mechanochemical synthesis: route to novel rock-salt-structured high-entropy oxides and oxyfluorides

A facile mechanochemical reaction at ambient temperature was successfully applied to synthesize novel single-phase rock-salt-structured high-entropy oxides, containing five, six and seven metal elements in equiatomic amounts. This synthesis approach overcomes the limitations of the commonly known synthesis procedures, which would result in multiple-phase compounds. Redox-sensitive elements, such as Fe$^{2+}$ and Mn$^{2+}$, can now be considered. The corresponding single-phase Li-containing high-entropy oxyfluorides were obtained by introducing LiF into the lattice using the same strategy. All materials show single-phase rock-salt structures with lattice parameters depending on the incorporated ion sizes. Solid solution states result in high configurational entropies, and all elements appear homogenously distributed over the whole cationic and anionic sublattice. The straightforward synthesis technique, combined with utilized simple binary oxide precursors, paves the way for a multitude of novel high-entropy oxide and oxyfluoride compounds. The compounds were studied by means of X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray spectroscopy and Mössbauer spectroscopy

Lithium containing layered high entropy oxide structures

Layered Delafossite-type Lix(M$_{1}$M$_{2}$M$_{3}$M$_{4}$M$_{5}$…M$_{n}$)O$_{2}$ materials, a new class of high-entropy oxides, were synthesized by nebulized spray pyrolysis and subsequent high-temperature annealing. Various metal species (M = Ni, Co, Mn, Al, Fe, Zn, Cr, Ti, Zr, Cu) could be incorporated into this structure type, and in most cases, single-phase oxides were obtained. Delafossite structures are well known and the related materials are used in different fields of application, especially in electrochemical energy storage (e.g., LiNi$_{x}$Co$_{y}$Mn$_{z}$O$_{2}$ [NCM]). The transfer of the high-entropy concept to this type of materials and the successful structural replication enabled the preparation of novel compounds with unprecedented properties. Here, we report on the characterization of a series of Delafossite-type high-entropy oxides by means of TEM, SEM, XPS, ICP-OES, Mössbauer spectroscopy, XRD including Rietveld refinement analysis, SAED and STEM mapping and discuss about the role of entropy stabilization. Our experimental data indicate the formation of uniform solid-solution structures with some Li/M mixing