Wood-Inspired Morphologically Tunable Aligned Hydrogel for High-Performance Flexible All-Solid-State Supercapacitors

Oriented microstructures are widely found in various biological systems for multiple functions. Such anisotropic structures provide low tortuosity and sufficient surface area, desirable for the design of high-performance energy storage devices. Despite significant efforts to develop supercapacitors with aligned morphology, challenges remain due to the predefined pore sizes, limited mechanical flexibility, and low mass loading. Herein, a wood-inspired flexible all-solid-state hydrogel supercapacitor is demonstrated by morphologically tuning the aligned hydrogel matrix toward high electrode-materials loading and high areal capacitance. The highly aligned matrix exhibits broad morphological tunability (47–12 µm), mechanical flexibility (0°–180° bending), and uniform polypyrrole loading up to 7 mm thick matrix. After being assembled into a solid-state supercapacitor, the areal capacitance reaches 831 mF cm−2 for the 12 µm matrix, which is 259% times of the 47 µm matrix and 403% times of nonaligned matrix. The supercapacitor also exhibits a high energy density of 73.8 µWh cm−2, power density of 4960 µW cm−2, capacitance retention of 86.5% after 1000 cycles, and bending stability of 95% after 5000 cycles. The principle to structurally design the oriented matrices for high electrode material loading opens up the possibility for advanced energy storage applications

The gl(M|N) Super Yangian and Its Finite Dimensional Representations

Methods are developed for systematically constructing the finite dimensional irreducible representations of the super Yangian Y(gl(M|N)) associated with the Lie superalgebra gl(M|N). It is also shown that every finite dimensional irreducible representation of Y(gl(M|N)) is of highest weight type, and is uniquely characterized by a highest weight. The necessary and sufficient conditions for an irrep to be finite dimensional are given.Comment: 14 pages plain late

Clearing residual planetesimals by sweeping secular resonances in transitional disks: a lone-planet scenario for the wide gaps in debris disks around Vega and Fomalhaut

Extended gaps in the debris disks of both Vega and Fomalhaut have been observed. These structures have been attributed to tidal perturbations by multiple super-Jupiter gas giant planets. Within the current observational limits, however, no such massive planets have been detected. Here we propose a less stringent `lone-planet' scenario to account for the observed structure with a single eccentric gas giant and suggest that clearing of these wide gaps is induced by its sweeping secular resonance. During the depletion of the disk gas, the planet's secular resonance propagates inward and clears a wide gap over an extended region of the disk. Although some residual intermediate-size planetesimals may remain in the gap, their surface density is too low to either produce super-Earths or lead to sufficiently frequent disruptive collisions to generate any observable dusty signatures. The main advantage of this lone-planet sweeping-secular-resonance model over the previous multiple gas giant tidal truncation scenario is the relaxed requirement on the number of gas giants. The observationally inferred upper mass limit can also be satisfied provided the hypothetical planet has a significant eccentricity. A significant fraction of solar or more massive stars bear gas giant planets with significant eccentricities. If these planets acquired their present-day kinematic properties prior to the depletion of their natal disks, their sweeping secular resonance would effectively impede the retention of neighboring planets and planetesimals over a wide range of orbital semi-major axes.Comment: 20 pages, 12 figures. Accepted for publication in Ap

Representations of Super Yangian

We present in detail the classification of the finite dimensional irreducible representations of the super Yangian associated with the Lie superalgebra $gl(1|1)$.Comment: 14 pages, plain latex, no figur

The Nature of Quantum Hall States near the Charge Neutral Dirac Point in Graphene

We investigate the quantum Hall (QH) states near the charge neutral Dirac point of a high mobility graphene sample in high magnetic fields. We find that the QH states at filling factors $\nu=\pm1$ depend only on the perpendicular component of the field with respect to the graphene plane, indicating them to be not spin-related. A non-linear magnetic field dependence of the activation energy gap at filling factor $\nu=1$ suggests a many-body origin. We therefore propose that the $\nu=0$ and $\pm1$ states arise from the lifting of the spin and sub-lattice degeneracy of the $n=0$ LL, respectively.Comment: 4 pages, 4 figures, to appear in Phys. Rev. Let

Quantum Spin Hall Effect

The quantum Hall liquid is a novel state of matter with profound emergent properties such as fractional charge and statistics. Existence of the quantum Hall effect requires breaking of the time reversal symmetry caused by an external magnetic field. In this work, we predict a quantized spin Hall effect in the absence of any magnetic field, where the intrinsic spin Hall conductance is quantized in units of $2 \frac{e}{4\pi}$. The degenerate quantum Landau levels are created by the spin-orbit coupling in conventional semiconductors in the presence of a strain gradient. This new state of matter has many profound correlated properties described by a topological field theory

Maximal planar scale-free Sierpinski networks with small-world effect and power-law strength-degree correlation

Many real networks share three generic properties: they are scale-free, display a small-world effect, and show a power-law strength-degree correlation. In this paper, we propose a type of deterministically growing networks called Sierpinski networks, which are induced by the famous Sierpinski fractals and constructed in a simple iterative way. We derive analytical expressions for degree distribution, strength distribution, clustering coefficient, and strength-degree correlation, which agree well with the characterizations of various real-life networks. Moreover, we show that the introduced Sierpinski networks are maximal planar graphs.Comment: 6 pages, 5 figures, accepted by EP