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Metastable 1T′-phase transition metal dichalcogenides (TMDs) attract increasing interests owing to their fascinating physicochemical properties in superconductors, optical materials, and energy storage. However, spontaneous 1T′ to 2H phase transition severely hinders practical application of 1T′ TMD. In this study, through systematic investigation and theoretical simulation of phase change of 1T′ WS2, we demonstrate ultrathin 1T′ WS2 has significantly higher intrinsic thermal and antioxidant stabilities than the bulk counterparts. 1T′ to 2H phase transition temperature increases from 120°C to 350°C and durability increases from 2 days to more than 5 months in the air as thickness of 1T′ WS2 is lessened from bulk to monolayer. The higher stability of thinner 1T′ WS2 is attributed to stiffened intralayer bonds and enhanced thermal conductivity, originated from weakened interlayer Coulombic interactions. The high intrinsic phase stabilities of ultrathin 1T′ TMDs can pave the way for their wide tempting practical applications.

Recently V-based Kagome metal attracted intense attention due to the coexistence of topological nontrivial electronic structure, charge density wave, and superconductivity. Here we report the fabrication and physical investigations of the single-crystalline thin flakes of the Kagome metal KV3Sb5. For the samples with the effective superconducting thickness of 7±2 nm, the Berezinskii-Kosterlitz-Thouless type behavior is revealed by the temperature dependent resistance and voltage-current data, which indicates the presence of two-dimensional superconductivity. Meanwhile, the temperature-independent resistance is observed in a wide field region, supplying the hallmark of the anomalous metallic state. Importantly, by comparing the interplay between the superconducting and anomalous metallic states of two samples with different levels of disorder, a striking competitive evolution with the external field between these two states is uncovered.

Supplementary Figure S1. Loss of heterozygosity of Ch22q genes in poorly differentiated (PDTC) and anaplastic thyroid cancers (ATC). Supplementary Figure S2. Focal NF2-exon 4 homozygous deletion in KHM-5M anaplastic thyroid cancer cells. Supplementary Figure S3. FISH for NF2 in anaplastic thyroid cancers. Supplementary Figure S4. NF2/Merlin defects in thyroid cancer cell lines. Supplementary Figure S5. Merlin inhibits RAC1-PAK activity. Supplementary Figure S6. Merlin effects on EGFR signaling and growth of RAS mutant thyroid cancer cell lines. Supplementary Figure S7. PCR of genomic DNA from mouse thyroid tissues of the indicated genotypes with primers that distinguish wild-type from mutant Hras alleles. Supplementary Figure S8. TEAD1 is the most abundant TEAD isoform in thyroid cancer cells. Supplementary Figure S9. A) Left, Concentration-dependent growth inhibitory effects of the MEK inhibitor selumetinib (AZD6244) in RAS mutant thyroid cancer cell lines cells. Black, null/low NF2. Red, wt NF2. The IC50 of each cell line is shown in the boxed legend. Right, Western blots for merlin, pMEK and pERK in the cell lines studied. B) C643 cells expressing scrambled (pLKO.1) or shNF2 were treated with FRAX, AZD or their combination at the indicated concentrations (nM) in 1 percent of serum. Cells were counted at 6 days (*p

The evolution of the physical properties of two-dimensional material from monolayer limit to the bulk reveals unique consequences from dimension confinement and provides a distinct tuning knob for applications. Monolayer 1T'-phase transition metal dichalcogenides (1T'-TMDs) with ubiquitous quantum spin Hall (QSH) states are ideal two-dimensional building blocks of various three-dimensional topological phases. However, the stacking geometry was previously limited to the bulk 1T'-WTe2 type. Here, we introduce the novel 2M-TMDs consisting of translationally stacked 1T'-monolayers as promising material platforms with tunable inverted bandgaps and interlayer coupling. By performing advanced polarization-dependent angle-resolved photoemission spectroscopy as well as first-principles calculations on the electronic structure of 2M-TMDs, we revealed a topology hierarchy: 2M-WSe2, MoS2, and MoSe2 are weak topological insulators (WTIs), whereas 2M-WS2 is a strong topological insulator (STI). Further demonstration of topological phase transitions by tunning interlayer distance indicates that band inversion amplitude and interlayer coupling jointly determine different topological states in 2M-TMDs. We propose that 2M-TMDs are parent compounds of various exotic phases including topological superconductors and promise great application potentials in quantum electronics due to their flexibility in patterning with two-dimensional materials.

Molybdenum disulfide (MoS2) with high theoretical capacity has been viewed as a promising anode for sodium-ion batteries, but suffers from inferior rate capability owing to the polaron-induced slow charge transfer. Herein, we proposed a polaron collapse strategy induced by electron-rich insertions to effectively solve the above issue. Specifically, 1D [MoS] chains are inserted into MoS2 to break the symmetry states of 2D layers and induce small-polaron collapse to gain fast charge transfer, so that the as-obtained thermodynamically stable Mo2S3 shows metallic behavior with 107 times larger electrical conductivity than that of MoS2. Theoretical calculations demonstrate that Mo2S3 owns highly delocalized anions, which substantially reduces the interactions of Na − S to efficiently accelerate Na+ diffusion, endowing Mo2S3 lower energy barrier (0.38 vs 0.65 eV of MoS2). The novel Mo2S3 anode exhibits a high capacity of 510 mAh g− 1 at 0.5 C and a superior high-rate stability of 217 mAh g− 1 at 40 C over 15000 cycles. Further in situ and ex situ characterizations reveal the in-depth reversible redox chemistry in Mo2S3. The proposed polaron collapse strategy for intrinsically facilitating charge transfer could be conducive to electrode design for fast-charging batteries.

PDMS (Polydimethylsiloxane) chips are increasingly important for the application of fluorescence measurements due to their auto-fluorescence free, excellent transparency, and biocompatibility. However, the design of PDMS microfluidic chips requires to fabricate plenty of molds for structure optimization, resulting in high cost. In the present, PDMS chips with nafion membrane were fabricated by simple and low-cost method for bull serum albumin (BSA) enrichment. To optimize the laser cutting and bonding parameters, simulation models were established using Bilinear Kinematic and Mooney-Rivlin models, respectively. The influence of laser power and cutting speed on the width and depth of the micro-channels was investigated. And the effect of bonding pressure on the deformation of PDMS micro-channel and stress distribution near the micro-channels was also analyzed. The leakage test and BSA enrichment demonstrated the practicability and feasibility of the present fabrication method in this work.

Re0.7W0.3Se2 has the best performance in 0.5 M H2SO4 with a Tafel slope of 65.3 mV dec−1, an overpotential of 141 mV at the current density of 10 mA cm−2.

Non-negative matrix factorization (NMF) has become a popular method for learning interpretable patterns from data. As one of the variants of standard NMF, convolutive NMF (CNMF) incorporates an extra time dimension to each basis, known as convolutive bases, which is well suited for representing sequential patterns. Previously proposed algorithms for solving CNMF use multiplicative updates which can be derived by either heuristic or majorization-minimization (MM) methods. However, these algorithms suffer from problems, such as low convergence rates, difficulty to reach exact zeroes during iterations and prone to poor local optima. Inspired by the success of alternating direction method of multipliers (ADMMs) on solving NMF, we explore variable splitting (i.e., the core idea of ADMM) for CNMF in this article. New closed-form algorithms of CNMF are derived with the commonly used β -divergences as optimization objectives. Experimental results have demonstrated the efficacy of the proposed algorithms on their faster convergence, better optima, and sparser results than state-of-the-art baselines.

Flexible strain sensors have an irreplaceable role in critical and emerging fields, such as electronic skins, flexible robots, and prosthetics. Although numerous efforts have been made to improve sensor sensitivity to meet specific application scenarios, the signal-to-noise ratio (SNR) is an extremely critical and non-negligible indicator, which takes into account higher sensitivity, meaning that they can also detect the noise signals with high sensitivity. Coincidentally, scorpions with ultrasensitive vibration sensilla also face such a dilemma. Here, it is found that the scorpion ingeniously uses the viscoelastic material in front of its slit sensilla to realize efficient preprocessing of the signal. Its mechanism is that the loss factor of materials changes with frequency, affecting energy storage and transmission. Inspired by this ingenious strategy, a bioinspired strain sensor insensitive to a low strain rate was designed using a two-step template transfer method. As a result, its relative change in resistance reached 110% under the same strain (0.3197%) but with different strain rates (0.1 Hz and ∼20 Hz). The noncontact vibration experiments also show different responses to low-frequency vibration and high-frequency impact. Moreover, it can also be used as a typical flexible strain sensor. Under the tensile state, it has a gauge factor (GF) as high as 4596 upon 0.6% strain, and the response time is 140 ms. Therefore, it is expected that this strain sensor will be used in many important ultraprecision measurement fields, especially when the measured signal is small.

Exploring new excellent electrocatalysts for the hydrogen evolution reaction (HER) is of significance for the development of hydrogen energy. Herein, a ternary chalcogenide (Pt3Pb2S2) is successfully designed and synthesized using layered PtS2 as a matrix. The energy level of the Pt 5d orbital is upshifted to the Fermi surface after replacing S atoms by Pb atoms, which results in the high conductivity of Pt3Pb2S2. In addition, the low-coordinated Pt atoms inserted in the voids of [Pt2Pb2S2] layers have a lower free energy of H* adsorption than do metallic Pt atoms, which endows Pt3Pb2S2 with excellent HER performance. The overpotential and Tafel slope of Pt3Pb2S2 toward HER activity are measured to be 43 mV at 10 mA cm-2 and 43 mV dec-1, respectively. More importantly, Pt3Pb2S2 shows high intrinsic HER catalytic activity and long-term stability. This work provides a promising strategy for designing novel excellent transition-metal chalcogenide electrocatalysts.

The quantum spin Hall (QSH) effect has attracted extensive research interest because of the potential applications in spintronics and quantum computing, which is attributable to two conducting edge channels with opposite spin polarization and the quantized electronic conductance of 2

Inducing new phases of transition metal dichalcogenides by controlling the d-electron-count has attracted much interest due to their novel structures and physicochemical properties. 1T'' ReSe

Active electronic states in transition metal dichalcogenides are able to prompt hydrogen evolution by improving hydrogen absorption. However, the development of thermodynamically stable hexagonal 2H-MoS2 as hydrogen evolution catalyst is likely to be shadowed by its limited active electronic state. Herein, the charge self-regulation effect mediated by tuning Mo−Mo bonds and S vacancies is revealed in metastable trigonal MoS2 (1T'''-MoS2) structure, which is favarable for the generation of active electronic states to boost the hydrogen evolution reaction activity. The optimal 1T'''-MoS2 sample exhibits a low overpotential of 158 mV at 10 mA cm−2 and a Tafel slope of 74.5 mV dec−1 in acidic conditions, which are far exceeding the 2H-MoS2 counterpart (369 mV and 137 mV dec−1). Theoretical modeling indicates that the boosted performance is attributed to the formation of massive active electronic states induced by the charge self-regulation effect of Mo−Mo bonds in defective 1T'''-MoS2 with rich S vacancies.

High-pressure investigation has been shown to be of paramount significance for changing the conventional lattice or bringing fascinating properties, especially inducing superconducting phases. Here we studied the application of pressure to the recently synthesized 2M-WS2 with the record Tc (8.8 K) among transition metal dichalcogenides (TMDs) at ambient pressure by electrical resistance investigations, synchrotron X-ray studies, and theoretical calculations. Tc in the initial 2M-WS2 dropped from the maximum to become undetected, accompanied by a phase transition into a semiconductor, 3R-WS2, at 15 GPa. The successive metallization and superconducting transitions in 3R-WS2 were observed at 48.8 GPa with Tc ≈ 2.5 K. This is the first experimental case in which superconductivity has been realized in the 3R phase among TMDs. We propose that the degradation of superconductivity in 2M-WS2 and the reemergence of superconductivity in 3R-WS2 are mainly attributable to changes in the density of states near the Fermi surface driven by the interlayer coupling.

The exploration of efficient electrocatalysts for the hydrogen evolution reaction (HER) is beneficial to obtain renewable clean energy. Herein, a new parkerite-type compound Pt3Bi2S2 was synthesized, constructed by [PtBi4S2] octahedra. The Bi 6p orbital electrons upshift the Pt 5d band to promote hydrogen adsorption. Moreover, the Bi-Pt orbital hybridization greatly improves the conductivity and accelerates the charge transfer during the electrocatalytic process. Hence, Pt3Bi2S2 exhibits a superior catalytic activity for the HER with a low overpotential of 61 mV (at j = 10 mA cm-2) and a Tafel slope of 51 mV dec-1. In addition, Pt3Bi2S2 has higher stability than commercial Pt/C. This work proposes a promising strategy for designing new excellent HER catalysts.

The discovery of 2D van der Waals (vdW) magnetic materials is of great significance to explore intriguing 2D magnetic physics and develop innovative spintronic devices. In this work, a new quasi-1D vdW layered compound CrZr

TV- $$L^1$$ is a classical diffusion–reaction model for low-level vision tasks, which can be solved by a duality-based iterative algorithm. Considering the recent success of end-to-end learned representations, we propose a TV-LSTM network to unfold the duality-based iterations of TV- $$L^1$$ into long short-term memory (LSTM) cells. In particular, we formulate the iterations as customized layers of a LSTM neural network. Then, the proposed end-to-end trainable TV-LSTMs can be naturally connected with various task-specific networks, e.g., optical flow, image decomposition and event-based optical flow estimation. Extensive experiments on optical flow estimation and structure + texture decomposition have demonstrated the effectiveness and efficiency of the proposed method.

Chevrel-phase superconducting compounds AyMo6Q8 (A = Pb, Mg, etc. and Q = S, Se, Te) have attracted much attention due to their ultrahigh upper critical magnetic fields (Hc2). However, the binary c...

Ischemia reperfusion (I/R)-induced arrhythmia is a serious complication in patients with cardiac infarction. Remodeling of connexin (Cx) 43, manifested as phosphorylation, contributes significantly to arrhythmogenesis. Integrin-linked kinase (ILK) attenuated ventricular remodeling and improved cardiac function in rats after myocardial infarction. We hypothesized that ILK, through Cx43 phosphorylation, would be protective against I/R-induced ventricular arrhythmias. Our study showed that I/R-induced ventricular arrhythmias were attenuated by an ILK agonist LPTP and worsened by the ILK inhibitor Cpd22. I/R disrupted Cx43 distribution, but it was partially normalized in the presence of LPTP. Compared with I/R, the phosphorylation of Akt was increased significantly after pretreatment with LPTP. The increase in phosphorylated Akt was physiologically significant because, in the presence of the Akt inhibitor MK2206, the protective effects of LPTP were blocked. This indicated that ILK activation prevented I/R-induced-ventricular arrhythmia, an effect potentially related to inhibition of Cx43 remodeling via Akt activation.

Layered transition metal dichalcogenide rhenium selenide (ReSe

The quantum spin Hall (QSH) effect has attracted extensive research interest because of the potential applications in spintronics and quantum computing, which is attributable to two conducting edge channels with opposite spin polarization and the quantized electronic conductance of 2e2/h. Recently, 2M-WS2, a new stable phase of transition metal dichalcogenides with a 2M structure showing an identical layer configuration to that of the monolayer 1T' TMDs, was suggested to be a QSH insulator as well as a superconductor with critical transition temperature around 8 K. Here, high-resolution angle-resolved photoemission spectroscopy (ARPES) and spin-resolved ARPES are applied to investigate the electronic and spin structure of the topological surface states (TSS) in the superconducting 2M-WS2. The TSS exhibits characteristic spin-momentum-locking behavior, suggesting the existence of long-sought nontrivial Z2 topological states therein. We expect that 2M-WS2 with co-existing superconductivity and TSS might host the promising Majorana bound states.

Pressure has always been an effective method for uncovering novel phenomena and properties in condensed matter physics. Here, an electrical transport study is carried on 2H-TaS

Mechanosensing of cells to extracellular matrix (ECM) is highly active and plays a crucial role in various physiological processes. Growing numbers of studies provide evidence that cell sensitivity to ECM stiffness is a complex stress-strain feedback process. However, the mechanisms that rule this process are still not fully known. Here, an alternative mechanosensing scheme of cells, which is different from the previous myosin-II-based mechanisms, is proposed by employing the tension in cortical cytoskeletons (CSKs) as a force module to probe the substrate. The molecular mechanotransduction from cortical CSKs, through actin filaments and focal adhesions, and finally to the substrate, is mechanically modeled to scale the dynamic traction forces of cells. The developed model captures the characteristic spread of cells with respect to ECM stiffness whereby the spread is fully developed on a stiff substrate but not on a soft one. Furthermore, durotactic migration of cells on an elastic-gradient substrate is successfully modeled by the current method. The cells are concluded to migrate, actuated by the polarized traction forces from the stiffness gradient of the substrate and the stiffness matching between cells and substrate. Finally, the cells are proposed to actively target the preferred substrate by following a rule of mechanical matching between cells and substrate. This study provides a theoretical tool to advance our knowledge regarding the passive mechanical properties and the active sensing of cells, and further promotes the discovery of mechanosensing mechanisms as well as the material design for embryonic development and tissue homeostasis.

Exploring new excellent electrocatalysts for the hydrogen evolution reaction (HER) is of significance for the development of hydrogen energy. Herein, a ternary chalcogenide (Pt

Limited by the conditions and performance of ground-based optical observations, it is difficult for us to obtain a plethora of optical cross section (OCS) data for some space objects (SOs). Unevenly distributed OCS data and unclear labels will affect the performance of SOs recognition based on neural networks. Furthermore, when we need to identify a new SO or SO category using deep neural network, the trained network model may no longer be applicable. We need to retrain the network with new training data. In order to alleviate these problems and improve the generalization and training convergence speed of SOs recognition networks, a novel, to the best of our knowledge, neural network model, ARSRNet, is proposed in this paper. The ARSRNet can identify SOs and their attitude accurately using only a small quantity of training OCS data and without clear labels. And the proposed network is able to adapt to new recognition tasks. Meanwhile, we propose an AdamRprop network optimization algorithm to accelerate network training and improve recognition accuracy. Experimental results show that the recognition accuracy of ARSRNet reaches 90.60% on the test OCS dataset. Compared with mainstream network optimization algorithms, the proposed AdamRprop is more appropriate for ARSRNet and can accelerate the convergence of ARSRNet.

Active electronic states in transition metal dichalcogenides are able to prompt hydrogen evolution by improving hydrogen absorption. However, the development of thermodynamically stable hexagonal 2H-MoS

The scaffold is essential to tissue engineering. In particular, the mechanical property of scaffolds has a significant impact on the success rate of regeneration. While numerous techniques exist for measuring mechanical properties, Compression test, three-point bending test, and nano-indentation test are the most common. Nevertheless, the mechanical property of porous structures cannot be accurately measured by previous testing methods. Combining superposition principles with the Flamant solution, this study developed semi-analytical solutions. Through compression testing and FEM simulation, the semi-analytical solution was fully validated. The solution can calculate not only the maximum stress of layer-by-layer construction of complex 3D scaffolds, but also the maximum load-bearing capacity if the mechanical property of the material is known.

The exploration of efficient electrocatalysts for the hydrogen evolution reaction (HER) is beneficial to obtain renewable clean energy. Herein, a new parkerite-type compound Pt3Bi2S2 was synthesized, constructed by [PtBi4S2] octahedra. The Bi 6p orbital electrons upshift the Pt 5d band to promote hydrogen adsorption. Moreover, the Bi-Pt orbital hybridization greatly improves the conductivity and accelerates the charge transfer during the electrocatalytic process. Hence, Pt3Bi2S2 exhibits a superior catalytic activity for the HER with a low overpotential of 61 mV (at j = 10 mA cm-2) and a Tafel slope of 51 mV dec-1. In addition, Pt3Bi2S2 has higher stability than commercial Pt/C. This work proposes a promising strategy for designing new excellent HER catalysts.

Determination of the crystal structure of Rb0.21(H2O)yWS2 is beneficial to understanding the topotactic reaction process to form metastable WS2. The temperature dependence of the electrical resistance indicates that Rb0.21(H2O)yWS2 is semiconducting at 80-300 K., Rb0.21(H2O)yWS2, rubidium hydrate di­thio­tungstate, is a new quasi two-dimensional sulfide. Its crystal structure consists of ordered WS2 layers, separated by disordered Rb+ ions and water mol­ecules. All atomic sites are located on mirror planes. The WS2 layers are composed of edge-sharing [WS6] octa­hedra and extend parallel to (001). The presence of structural water was revealed by thermogravimetry, but the position and exact amount could not be determined in the present study. The temperature dependence of the electrical resistance indicates that Rb0.21(H2O)yWS2 is semiconducting between 80–300 K.

The nocturnal scorpion Heterometrus petersii uses Basitarsal Compound Slit Sensilla (BCSS) as mechanoreceptor to detect mechanical signal (e.g. substrate vibration, cyclic loads caused by walking) without fatigue failure such as initiation of fatigue crack and further propagation of crack-shaped slit. The outstanding perceptive function has been discovered for over half a century. However, it is not yet clear about the microstructure, material composition and micromechanical property which are all important factors that determine the fatigue fracture resistance of the BCSS. Here, the microscopic characteristics of the BCSS were thoroughly studied. The results indicate that anti-fatigue resilin and stiff chitinous cuticle form multilayered composite as the main body of the BCSS. Meanwhile, the pre-existing slit as mechanosensory structure is covered by cuticular membrane which has different mechanical property with the epicuticle. Theoretical analysis shows that the structure-composition-property synergistic relations of composites confer on the BCSS with extreme fatigue fracture tolerance.

Aβ1-42, which is highly toxic to neural cells, is commonly present in the brains of people with Alzheimer's disease. In this study, dynamic changes in cell mechanics were monitored under Aβ-induced toxicity. To investigate the changes in cellular mechanical properties, we used Aβ1-42 oligomer at different concentrations to treat human neuroblastoma SH-SY5H cells. Results demonstrated a two-stage dynamic change in cell mechanics during neurodegeneration. Additionally, Young's modulus (YM) of the treated cells increased in a short period. The reasons include alteration in surface tension, osmotic pressure, and actin polymerization. Rough cellular membranes were observed from atomic force microscope (AFM) measurement. However, the cellular YM gradually decreased when the cells were continuously exposed to Aβ1-42 or to a high concentration of Aβ1-42. The major reason for the decreased YM was microtubule disassembly. Dynamic change in YM reflects different activities in cytoplasm in response to Aβ1-42. The characteristic changes in cell mechanics provided insights into the dynamic neurodegeneration process of cells induced by Aβ1-42 oligomer.

Noncentrosymmetric MoS2 semiconductors (1H, 3R) possess not only novel electronic structures of spin-orbit coupling (SOC) and valley polarization but also remarkable nonlinear optical effects. A more interesting noncentrosymmetric structure, the so-called 1T‴-MoS2 layers, was predicted to be built up from [MoS6] octahedral motifs by theoreticians, but the bulk 1T‴ MoS2 or its single crystal structure has not been reported yet. Here, we have successfully harvested 1T‴ MoS2 single crystals by a topochemical method. The new layered structure is determined from single-crystal X-ray diffraction. The crystal crystallizes in space group P31m with a cell of a = b = 5.580(2) A and c = 5.957(2) A, which is a √3 a × √3 a superstructure of 1T MoS2 with corner-sharing Mo3 triangular trimers observed by the STEM. 1T‴ MoS2 is verified to be semiconducting and possesses a band gap of 0.65 eV, different from metallic nature of 1T or 1T' MoS2. More surprisingly, the 1T‴ MoS2 does show strong optical second-harmonic generation signals. This work provides the first layered noncentrosymmetric semiconductor of edge-sharing MoS6 octahedra for the research of nonlinear optics.

This work reports the synthesis of a new quasi two-dimensional layered compound, K0.36(H2O)yWS2, for aqueous potassium ion storage. Its crystal structure determined by single crystal X-ray diffraction is composed of WS2 layers and disordered hydrated K+ stacking along the c direction alternately. Due to the large interlayer spacing and high conductivity, K0.36(H2O)yWS2 is demonstrated to be a stable host for reversible intercalation and de-intercalation of hydrated K+ in K2SO4 aqueous solution.

In this paper, we explore a scalable deep reinforcement learning (DRL) method for environments with multi-agents. Due to the explosive increase of the input dimensionality with the number of agents, most existing DRL methods are only able to cope with single-agent settings, or for only a small number of agents. To address this problem, we adopt a centralized training with decentralized execution framework, in which an observation embedding is used to reduce the curse of dimensionality. Perturbations are injected into the parameter space of the actor network for each agent to encourage exploration. The experiments demonstrate the effectiveness of the proposed approach on both cooperative and competitive environments.

In this communication, we report a new-phase 2M WSe2 with a monoclinic space group C2/m. 2M WSe2 presents a metallic behavior under ambient pressure and shows a superconducting transition with a maximum Tc of 7.3 K at 10.7 GPa, which arises from the enhanced density of states near the Fermi surface upon pressurization.