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Superconductor-insulator/metal transition (SIT/SMT) represents a prototype of quantum phase transition, where quantum fluctuation plays a dominant role and dramatically changes the physical properties of low-dimensional superconducting systems. Recent observation of quantum Griffiths singularity (QGS) offers an essential perspective to understand the subtleties of quantum phase transition in two-dimensional superconductors. Here we study the magnetic field induced SMT in ultrathin crystalline Pb films down to ultralow temperatures. The divergent critical exponent is observed when approaching zero temperature quantum critical point, indicating QGS. Distinctively, the anomalous phase boundary of SMT that the onset critical field decreases with decreasing temperatures in low temperature regime distinguishes our observation from previous reports of QGS in various two-dimensional superconductors. We demonstrate that the anomalous phase boundary originates from the superconducting fluctuations in ultrathin Pb films with pronounced spin-orbit interaction. Our findings reveal a novel aspect of QGS of SMT in two-dimensional superconductors with anomalous phase boundary., Evidence of quantum phase transitions is normally difficult to be detected. Here, Liu and Wang et al. report divergent critical exponent in ultrathin Pb films with superconducting fluctuations and spin-orbit interaction, indicating an anomalous quantum Griffiths singularity of superconductor-metal transition.

Topological insulators, a class of typical topological materials in both two dimensions and three dimensions, are insulating in bulk and metallic at surface. The spin-momentum locked surface states and peculiar transport properties exhibit promising potential applications on quantum devices, which generate extensive interest in the last decade. Dephasing is the process of the loss of phase coherence, which inevitably exists in a realistic sample. In this review, we focus on recent progress in dephasing effects on the topological insulators. In general, there are two types of dephasing processes: normal dephasing and spin dephasing. In two-dimensional topological insulators, the phenomenologically numerical investigation shows that the longitudinal resistance plateaus is robust against normal dephasing but fragile with spin dephasing. Several microscopic mechanisms of spin dephasing are then discussed. In three-dimensional topological insulators, the helical surface states exhibit a helical spin texture due to the spin-momentum locking mechanism. Thus, normal dephasing has close connection to spin dephasing in this case, and gives rise to anomalous “gap-like” feature. Dephasing effects on properties of helical surface states are investigated.

The Majorana zero mode in the semiconductor-superconductor nanowire is one of the promising candidates for topological quantum computing. Recently, in islands of nanowires, subgap-state energies have been experimentally observed to oscillate as a function of the magnetic field, showing a signature of overlapped Majorana bound states. However, the oscillation amplitude either dies away after an overshoot or decays, sharply opposite to the theoretically predicted enhanced oscillations for Majorana bound states. We reveal that a steplike distribution of spin-orbit coupling in realistic devices can induce the decaying Majorana oscillations, resulting from the coupling-induced energy repulsion between the quasiparticle spectra on the two sides of the step. This steplike spin-orbit coupling can also lead to decaying oscillations in the spectrum of the Andreev bound states. For Coulomb-blockade peaks mediated by the Majorana bound states, the peak spacings have been predicted to correlate with peak heights by a $\pi/2$ phase shift, which was ambiguous in recent experiments and may be explained by the steplike spin-orbit coupling. Our work will inspire more works to reexamine effects of the nonuniform spin-orbit coupling, which is generally present in experimental devices., Comment: 7 pages, 4 figures

In the semiclassical regime, the chiral anomaly of the Weyl semimetals is demonstrated by the quadratic longitudinal magnetoconductivity. Recently the planar Hall effect is proposed in the same systems, where the Hall conductivity depends quadratically on the magnetic field. If the Weyl cones are tilted, both the chiral chemical potential and the anomalous velocity contribute a linear term to the conductivities. We investigate the electronic transport of a tilted Weyl semimetal in the presence of an in-plane magnetic field. The results show that both the longitudinal and the Hall conductivities contain a linear term in magnetic field besides the quadratic terms and the angular dependence of them is different from the case without tilting. The correction of the phase space volume factor is also studied, which shows effects on both the angular dependence as well as the amplitudes of the conductivities. The angular dependence of the conductivities, showing the signature of the planar Hall effect, is experimentally verifiable.

We study the confined bound states in circular bilayer graphene quantum dots. Using the semiclassical Einstein-Brillouin-Keller quantization rule, we predict that valley levels inside the quantum dot undergo three stages: splitting, crossing, and recombining when varying the applied magnetic field. This exotic phenomenon originates from the Berry phase, which increases from zero to $2\ensuremath{\pi}$ with the magnetic field and has opposite signs for the two inequivalent valleys. To further confirm this phenomenon, we perform a fully quantum mechanical calculation based on a low-energy continuum model and a real space tight-binding model, and show that the valley effect can be explicitly observed by scanning-tunneling spectroscopy measurements. Moreover, we propose an efficient valley filter device as an application of this valley effect, which can be used to manipulate the valley degree of freedom in valleytronics.

We extend the scope of the Klein bottle entropy, originally introduced by [Tu, Phys. Rev. Lett. 119, 261603 (2017)] in the rational conformal field theory (CFT), to the compactified boson CFT, which are relevant to the studies of Luttinger liquids. We first review the Klein bottle entropy in rational CFT and discuss details of how to extract the Klein bottle entropy from lattice models using the example of the transverse field Ising model. We then go beyond the scope of rational CFT and study the Klein bottle entropy $\ln g$ in the compactified boson CFT, which turns out to have a straightforward relation to the compactification radius $R$, $\ln g = \ln R$. This relation indicates a convenient and efficient method to extract the Luttinger parameter from lattice model calculations. Our numerical results on the Klein bottle entropy in the spin-$1/2$ XXZ chain show excellent agreement with the CFT predictions, up to some small deviations near the isotropic point, which we attribute to the marginally irrelevant terms. For the $S = 1$ XXZ chain that cannot be exactly solved, our numerical results provide an accurate numerical determination of the Luttinger parameter in this model., Comment: 18 pages, 6 figures, published version

In this work, we study the disorder effect on topological metals that support a pair of helical edge modes deeply embedded inside the gapless bulk states. Strikingly, we predict that a quantum spin Hall (QSH) phase can be obtained from such topological metals without opening a global band gap. To be specific, disorder can lead to a pair of robust helical edge states which is protected by an emergent $Z_2$ topological invariant, giving rise to a quantized conductance plateau in transport measurements. These results are instructive for solving puzzles in {various transport experiments on QSH materials} that are intrinsically metallic. This work also will inspire experimental realization of the QSH effect in disordered topological metals., Comment: 7 pages, 7 figures

A planar Josephson junction with a normal metal attached on its top surface will form a hollow nanowire structure due to its three dimensional nature. In such hollow nanowire structure, the magnetic flux induced by a small magnetic field (about 0.01T) will tune the system into topologically non-trivial phase and therefore two Majorana zero-modes will form at the ends of the nanowire. Through tuning the chemical potential of the normal metal, the topologically non-trivial phase can be obtained for almost all energy within the band. Furthermore, the system can be conveniently tuned between the topologically trivial and non-trivial phases via the phase difference between the superconductors. Such device, manipulable through flux, can be conveniently fabricated into desired 2D networks. Finally, we also propose a cross-shaped junction realizing the braiding of Majorana zero-modes through manipulating the phase differences., Comment: 5 pages, 4 figures

Unconventional responses upon breaking discrete or crystal symmetries open avenues for exploring emergent physical systems and materials. By breaking inversion symmetry, a nonlinear Hall signal can be observed, even in the presence of time-reversal symmetry, quite different from the conventional Hall effects. Low-symmetry two-dimensional materials are promising candidates for the nonlinear Hall effect, but it is less known when a strong nonlinear Hall signal can be measured, in particular, its connections with the band-structure properties. By using model analysis, we find prominent nonlinear Hall signals near tilted band anticrossings and band inversions. These band signatures can be used to explain the strong nonlinear Hall effect in the recent experiments on two-dimensional WTe$_{2}$. This Letter will be instructive not only for analyzing the transport signatures of the nonlinear Hall effect but also for exploring unconventional responses in emergent materials.

In this study, a kind of electronically controlled liquid-crystal microlens array (LCMLA) with plane swing focus and tunable focal length instead of a commonly microlens array with a fixed focal length and then focus distribution for highresolution image acquisition, wavefront measurement, and distortion wavefront correction, is proposed. The LCMLA mainly consists of two glass substrates coated with a film of indium-tin-oxide (ITO) transparent material on one side. Each sub-unit top layer is composed of four sub-square electrodes, and the bottom layer is a circular electrode. The key technological steps in electrode fabrication contain an ultraviolet lithography, a dry etching (ICP etching), and final electron beam evaporation and overlay. The current LCMLA can be realized in three operating modes under external driving circuitry, including intensity image acquiring, wavefront measurement and distortion wavefront correction. The LCMLA is only in the image acquisition mode under the condition of no driving electrical signal. As the same driving electrical signals are applied onto the top four sub-electrodes of each sub-unit, the LCMLA is in the wavefront measurement mode. The LCMLA is in the key wavefront correction mode when different driving electrical signals are simultaneously applied onto the top four sub-electrodes of each sub-unit. Experiments show that the focal point of the LCMLA can be moved along the optical axis and over the focal plane by applying appropriate driving voltage signals.

In this paper, a new type of electrically controlled liquid-crystal microlens arrays (ECLCMAs) based on plane nonuniform spiral microcoils (PNSMs) is proposed. The microlens array is based on a nematic liquid-crystal material, which presents a special characteristics of optical anisotropy and birefringence, and is fabricated by common ultraviolet lithography and dry ICP etching process to form needed PNSMs pattern. In the ECLCMAs, a glass substrate precoated by a film of indium tin oxide (ITO) on both surfaces of substrate is adopted. The key center electrode for shaping each functioned LC cell is drilled using a laser etching and emery polishing process. Metallic indium particles are selected to connect the upper and lower ITO layers. The design can guarantee the continuity of the upper and lower plates and does not affect the electric and magnetic fields generated by spiral microcoils, which are utilized to drive LC film to present needed functions of further controlling and adjusting incident microbeam distribution, which is preprocessed by main objective lens system. After an AC voltage signal is applied across the microcoil, an effective electromagnetic field can be formed in LC cell so as to drive LC molecules to rotate and thus demonstrates an electrically tuning focus. The simulations show that the design of patterned PNSMs can be effectively used to form a sufficient electric and magnetic fields that are directly used to rotate LC molecules and thus form a gradient refractive index distribution for converging incident microbeams so as to show a higher controlling-light efficiency than that of traditional patterned microelectrodes. The proposed method laid a solid foundation for future smart ECLCMAs.

Recently, a zero Hall conductance plateau with random domains is experimentally observed in quantum anomalous Hall (QAH) effect. We study the effects of random domains on the zero Hall plateau in QAH insulators. We find the structure inversion symmetry determines the scaling property of the zero Hall plateau transition in the QAH systems. In the presence of structure inversion symmetry, the zero Hall plateau state shows a quantum-Hall-type critical point, originating from the two decoupled subsystems with opposite Chern numbers. However, the absence of structure inversion symmetry leads to mixture between these two subsystems, gives rise to a line of critical points, and dramatically changes the scaling behavior. Hereinto, we predict a Berezinskii-Kosterlitz-Thouless-type transition during the Hall conductance plateau switching in the QAH insulators. Our results are instructive for both theoretic understanding of the zero Hall plateau transition and future transport experiments in the QAH insulators., 5 pages, 4 figures

Circulating tumor DNA (ctDNA) carries genetic information consistent with tumor cells and has potential value for molecular diagnosis of tumors. The present study analysed the gene mutations of plasma circulating cell-free DNA (cfDNA) and tumor tissue DNA in hepatocellular carcinoma (HCC) patients and explored the clinical application value of plasma cfDNA as a tumor marker in HCC molecular diagnosis. Samples from 29 patients with primary HCC were collected. Hotspot mutations in 50 tumor-associated genes were analysed using amplicon sequencing technology and gene loci with a mutant allele frequency (MAF) >1% were analysed. 35 mutant genes in total were detected by deep sequencing method of which the genes with maximum mutation frequencies were TP53, ATM, and ALK. In addition, a total of 21 patients were found to have a consistent gene mutation in plasma cfDNA and tumor tissue DNA and 17 cases had consistent gene mutations in the paracancerous tissue and tumor tissue DNA. Further analysis showed that the MAFs in the TP53, CTNNB1, PIK3CA, and CDKN2A genes were higher in patients with tumor diameters >5 cm than those with tumor diameters

The emerging field of superconductor (SC) spintronics has attracted intensive attentions recently. Many fantastic spin dependent properties in SC have been discovered, including the observation of large magnetoresistance, long spin lifetimes and the giant spin Hall effect in SC, as well as spin supercurrent in Josephson junctions, etc. Regarding the spin dynamic in SC films, few studies has been reported yet. Here, we report the investigation of the spin dynamics in an s-wave superconducting NbN film via spin pumping from an adjacent insulating ferromagnet GdN layer. A profound coherence peak of the Gilbert damping is observed slightly below the superconducting critical temperature of the NbN layer, which is consistent with recent theoretical studies. Our results further indicate that spin pumping could be a powerful tool for investigating the spin dynamics in 2D crystalline superconductors., 11 pages, 4 figures, and SI

The conductance measurement of a half quantized plateau in a quantum anomalous Hall insulator-superconductor structure is reported by a recent experiment [Q. L. He \textit{et al.}, Science 357, 294-299 (2017)], which suggests the existence of the chiral Majorana fermion modes. However, such half quantized conductance plateau may also originates from a disorder-induced metallic phase. To identify the exact mechanism, we study the transport properties of such a system in the presence of strong disorders. Our results show that the local current density distributions of these two mechanisms are different. In particular, the current noises measurement can be used to distinguish them without any further fabrication of current experimental setup.

In this paper, a polarization difference liquid-crystal microlens array (PD-LCMLA) for three dimensional imaging application through turbid media is fabricated and demonstrated. This device is composed of a twisted nematic liquidcrystal cell (TNLCC), a polarizer and a liquid-crystal microlens array. The polarizer is sandwiched between the TNLCC and LCMLA to help the polarization difference system achieving the orthogonal polarization raw images. The prototyped camera for polarization difference imaging has been constructed by integrating the PD-LCMLA with an image sensor. The orthogonally polarized light-field images are recorded by switching the working state of the TNLCC. Here, by using a special microstructure in conjunction with the polarization-difference algorithm, we demonstrate that the three-dimensional information in the scattering media can be retrieved from the polarization-difference imaging system with an electrically tunable PD-LCMLA. We further investigate the system’s potential function based on the flexible microstructure. The microstructure provides a wide operation range in the manipulation of incident beams and also emerges multiple operation modes for imaging applications, such as conventional planar imaging, polarization imaging mode, and polarization-difference imaging mode. Since the PD-LCMLA demonstrates a very low power consumption, multiple imaging modes and simple manufacturing, this kind of device presents a potential to be used in many other optical and electro-optical systems.

In this paper, a kind of electronically controlled liquid crystal microlens arrays (LCMAs) with non-uniform coil electrodes arrays (NCEAs) is presented. The focal length of the electronically controlled LCMAs can be easily adjusted by applying the appropriate AC signal. The structure of the LCMAs is designed as a NCE array, which can then produce non-uniform electric field to drive liquid crystal molecules. The top electrode is fabricated by depositing an indium-tinoxide (ITO) semiconductor transparent conductive film based on a non-uniform electrode coil, and the bottom electrode is a conventional plate electrode. Due to the design of non-uniform electrode coil array is small, in addition to the traditional lithography process, the etching process we used is dry etching (ICP etching). The simulation results show that, the focal length of the LCMAs with the NCEAs can be tuned easily by applying the appropriate AC signal.

Under the condition of existing intense turbulence, the object's wavefront may be severely distorted. So, the wavefront sensors based on the traditional microlens array (MLA) with a fixed focal length can not be used to measure the wavefront effectively. In order to obtain a larger measurement range and higher measurement accuracy, we propose a liquid-crystal microlens array (LCMLA) with needed ability of swing focus over the focal plane and further adjusting focal length, which is constructed by a dual patterned ITO electrodes. The main structure of the LCMLA is divided into two layers, which are made of glass substrate with ITO transparent electrodes. The top layer of each liquid-crystal microlens consists of four rectangular electrodes, and the bottom layer is a circular electrode. In common optical measurements performed, the operations are carried out such as adding the same signal voltage over four electrodes of each microlens to adjust the focal length of the lens cell and adding a signal voltage with different RMS amplitude to adjust the focus position on the focal plane. Experiments show that the LCMLA developed by us demonstrate a desired focal length adjustable function and dynamic swing ability, so as to indicate that the method can be used not only to measure wavefront but also correct the wavefront with strong distortion.

Background Identification of novel MDM2 or p53 binding proteins may reveal undefined oncogenes, tumor suppressors, signaling pathways and possible treatment targets. Methods By means of immunoprecipitation and Mass Spectrometry analysis, we aimed to identify novel regulators of the MDM2-p53 pathway. We further clarified the impact of MYL6B on the p53 protein level and on the process of apoptosis. We also investigated the role of MYL6B in hepatocellular carcinoma by clone formation assay and by determining the correlation between its expression and prognosis of HCC patients. Results We identified a novel MDM2 and p53 binding protein, MYL6B. It is a myosin light chain that could bind myosin II heavy chains to form non-muscle myosin II holoenzymes (NMII). We found that MYL6B could facilitate the binding of MDM2 to p53, which consequently promotes the ubiquitination and degradation of p53 protein. We further proved that MYL6B exerts the suppression effect on p53 as part of NMII holoenzymes because inhibiting the ATPase activity of myosin II heavy chain largely blocked this effect. We also discovered that MYL6B is overexpressed in HCC tissues and linked to the bad prognosis of HCC patients. Knocking out of MYL6B dramatically suppressed the clonogenic ability and increased the apoptosis level of HCC cell lines. Conclusions To summary, our results demonstrate that MYL6B is a putative tumor driver gene in HCC which could promote the degradation of p53 by enhancing its’ MDM2-mediated ubiquitination.

Spin superfluid is a novel emerging quantum matter arising from the Bose-Einstein condensate (BEC) of spin-1 bosons. We demonstrate the spin superfluid ground state in canted antiferromagnetic Cr2O3 thin film at low temperatures via nonlocal spin transport. A large enhancement of the nonlocal spin signal is observed below ~ 20 K, and it saturates from ~ 5 K down to 2 K. We show that the spins can propagate over very long distances (~ 20 micro meters) in such spin superfluid ground state and the nonlocal spin signal decreases very slowly as the spacing increases with an inverse relationship, which is consistent with theoretical prediction. Furthermore, spin superfluidity has been investigated in the canted antiferromagnetic phase of the (11-20)-oriented Cr2O3 film, where the magnetic field dependence of the associated critical temperature follows a two-thirds power law near the critical point. The experimental demonstration of the spin superfluid ground state in canted antiferromagnet will be extremely important for the fundamental physics on the BEC of spin-1 bosons and paves the way for future spin supercurrent devices, such as spin-Josephson junctions., Comment: Main text 8 pages, 4 figures, Supplementary Materials 5 pages, 15 SI figures

We study the nonlocal transport property of Majorana quasiparticle states (MQPs) in a normal lead--topological superconducting wire--normal lead system. We find that the tunneling coefficient of the electron transmission process displays an interesting even-odd interference behavior. However, this even-odd interference behavior is difficult to observe in the tunneling coefficient of the crossed Andreev reflection process (CAR). We show that this even-odd interference behavior is directly related to the self-Hermitian property of MQPs. Due to the self-Hermitian property, the correction to the transport in the electron transmission process is in the first order while the correction to the CAR process is in the higher order. Thus, the interference behavior is more significant in the electron transmission process than in the CAR process. Such a unique transport property demonstrates the nonlocal and self-Hermitian characteristics of MQPs.

We study spin transport through a normal metal-spin superconductor junction. A spin-flip reflection is demonstrated at the interface, where a spin-up electron incident from the normal metal can be reflected as a spin-down electron and the spin $2\times \hbar/2$ will be injected into the spin superconductor. When the (spin) voltage is smaller than the gap of the spin superconductor, the spin-flip reflection determines the transport properties of the junction. We consider both graphene-based (linear-dispersion-relation) and quadratic-dispersion-relation normal metal-spin superconductor junctions in detail. For the two-dimensional graphene-based junction, the spin-flip reflected electron can be along the specular direction (retro-direction) when the incident and reflected electron locates in the same band (different bands). A perfect spin-flip reflection can occur when the incident electron is normal to the interface, and the reflection coefficient is slightly suppressed for the oblique incident case. As a comparison, for the one-dimensional quadratic-dispersion-relation junction, the spin-flip reflection coefficient can reach 1 at certain incident energies. In addition, both the charge current and the spin current under a charge (spin) voltage are studied. The spin conductance is proportional to the spin-flip reflection coefficient when the spin voltage is less than the gap of the spin superconductor. These results will help us get a better understanding of spin transport through the normal metal-spin superconductor junction., 11 pages, 9 figures

The topological semimetal $\ensuremath{\beta}\text{\ensuremath{-}}{\mathrm{Ag}}_{2}\mathrm{Se}$ features a Kramers-Weyl node at the origin in momentum space and a quadruplet of spinless Weyl nodes, which are annihilated by spin-orbit coupling. We show that single-crystalline $\ensuremath{\beta}\text{\ensuremath{-}}{\mathrm{Ag}}_{2}\mathrm{Se}$ manifests giant Shubnikov--de Haas oscillations in the longitudinal magnetoresistance, which stem from a small electron pocket that can be driven beyond the quantum limit by a field less than 9 T. This small electron pocket is a remainder of the spin-orbit annihilated Weyl nodes and thus encloses a Berry-phase structure. Moreover, we observed a negative longitudinal magnetoresistance when the magnetic field is beyond the quantum limit. Our experimental findings are complemented by thorough theoretical band-structure analyses of this Kramers-Weyl semimetal candidate, including first-principles calculations and an effective $\mathbit{k}\ifmmode\cdot\else\textperiodcentered\fi{}\mathbit{p}$ model.

We study the conductance fluctuation in topological semimetals. Through statistic distribution of energy levels of topological semimetals, we determine the dominant parameters of universal conductance fluctuation (UCF), i.e., the number of uncorrelated bands $k$, the level degeneracy $s$, and the symmetry parameter $\beta$. These parameters allow us to predict the zero-temperature intrinsic UCF of topological semimetals by the Altshuler-Lee-Stone theory. Then, we obtain numerically the conductance fluctuations for topological semimetals of quasi-1D geometry. We find that for Dirac/Weyl semimetals, the theoretical prediction coincides with the numerical results. However, a non-universal conductance fluctuation behavior is found for topological nodal line semimetals, i.e., the conductance fluctuation amplitude increases with the enlargement of SOC strength. We find that such unexpected parameter-dependent phenomena of conductance fluctuation are related to Fermi surface shape of 3D topological semimetals. These results will help us to understand the existing and future experimental results of UCF in 3D topological semimetals., Comment: 9 pages, 8 figures

Using a nonequilibrium-Green-function method, we numerically studied the transport properties of a superconductor-graphene-superconductor Josephson junction hybrid system in the quantum Hall regime. Our numerical calculations show that there are two interference patterns of the critical current due to the unique band structure of graphene. One is caused by the usual intraband Andreev retroreflection process, and the other one is caused by the interband specular Andreev reflection process. In the Andreev retroreflection regime, chiral Andreev edge states are formed and a distinct supercurrent can be observed. The critical current displays an AB oscillation behavior and the period is approximately $2{\mathrm{\ensuremath{\Phi}}}_{0}=h/e$. As for the specular Andreev refection process, the reflected holes are bent back to the reverse direction of the incident electrons and the supercurrent flows along both edges. It is similar to a superconductor ring Josephson junction and the period is ${\mathrm{\ensuremath{\Phi}}}_{0}=h/2e$. However, the critical current for the specular Andreev reflection process is very small and is unlikely to be observable in an experiment. Thus, we conclude that our numerical calculations are inconsistent to the experimental findings by Amet et al. [Science 352, 966 (2016)].

We investigate the quantum tunneling and Andreev reflection in a top-gated quantum anomalous Hall insulator proximity coupled with a superconductor junction. A quantized perfect crossed Andreev reflection with its coefficient being integer 1 is obtained and all other scattering processes (the normal reflection, normal tunneling, and local Andreev reflection) are completely suppressed when the topological superconductor phase with Chern number $\mathcal{N}=1$ is realized. This perfect crossed Andreev reflection originates from the tunneling of the chiral Majorana edge states, and the phase of tunneling amplitude only being 0 and $\ensuremath{\pi}$ plays a decisive role. Furthermore, because of the chiral characteristic of the Majorana edge states, the perfect crossed Andreev reflection is robust against the disorder and can work in a wide range of system parameters.

Ubiquitinlation of proteins is prevalent and important in both normal and pathological cellular processes. Deubiquitinating enzymes (DUBs) can remove the ubiquitin tags on substrate proteins and dynamically regulate the ubiquitination process. The PPPDE family proteins were predicted to be a novel class of deubiquitinating peptidase, but this has not yet been experimentally proved. Here we validated the deubiquitinating activity of PPPDE1 and revealed its isopeptidase activity against ubiquitin conjugated through Lys 48 and Lys 63. We also identified ribosomal protein S7, RPS7, as a substrate protein of PPPDE1. Moreover, PPPDE1 could mediate the ubiquitin chain editing of RPS7, deubiquitinating Lys 48-linked ubiquitination, and finally stabilize RPS7 proteins. Taken together, we report that PPPDE1 is a novel deubiquitinase that belongs to a cysteine isopeptidase family.

Discovery of log-periodic quantum oscillations may open a new chapter in the nearly 90-year history of quantum oscillations., Quantum oscillations are usually the manifestation of the underlying physical nature in condensed matter systems. Here, we report a new type of log-periodic quantum oscillations in ultraquantum three-dimensional topological materials. Beyond the quantum limit (QL), we observe the log-periodic oscillations involving up to five oscillating cycles (five peaks and five dips) on the magnetoresistance of high-quality single-crystal ZrTe5, virtually showing the clearest feature of discrete scale invariance (DSI). Further, theoretical analyses show that the two-body quasi-bound states can be responsible for the DSI feature. Our work provides a new perspective on the ground state of topological materials beyond the QL.

Summary Regulating mechanisms underlying hepatic myeloid-derived suppressor cell (MDSC) accumulation remain to be described. Here, we provide evidence for the involvement of tumour-activated liver stromal cells in the process of hepatic MDSCs migration and accumulation. Our data showed an elevated frequency of MDSCs in the liver of tumour-bearing mice. Moreover, tumour-activated liver stromal cells promote MDSC migration into the liver site. Further investigation indicated higher levels of cytokine and chemokine expression in liver stromal cells after exposure to the tumour-conditioned supernatant. Notably, the expression levels of proinflammatory factors, mainly including macrophage colony stimulating factor (M-CSF), transforming growth factor-β (TGF-β), monocyte chemotactic protein-1 (MCP-1) and stromal-derived factor-1 (SDF-1), increased after treatment with tumour-conditioned supernatant, and blockade of MCP-1 or SDF-1 decreased the proportion of tumour infiltrated MDSCs in mice co-transplanted with liver stromal cells and tumour cells, but not in mice with only tumour cells injection. These findings demonstrate that tumour-activated liver stromal cells produce higher levels of chemokines and cytokines, which may contribute to MDSC accumulation into the liver site in patients with liver cancer.

We report comprehensive studies of the single crystal growth and electrical transport properties for various samples of TaAs, the first experimentally confirmed inversion symmetry-breaking Weyl semimetal. The transport parameters for different samples are obtained through the fitting of the two band model and the analysis of Shubnikov de Haas oscillations. We find that the ratio factor of transport lifetime to quantum lifetime is intensively enhanced when the Fermi level approaches the Weyl node. This result is consistent with the side-jump interpretation derived from a chirality-protected shift in the scattering process for a Weyl semimetal., This is a modified version of arXiv:1502.00251

Since the concept of spin superconductor was proposed, all the related studies concentrate on spin-polarized case. Here, we generalize the study to spin-non-polarized case. The free energy of non-polarized spin superconductor is obtained, and the Ginzburg-Landau-type equations are derived by using the variational method. These Ginzburg-Landau-type equations can be reduced to the spin-polarized case when the spin direction is fixed. Moreover, the expressions of super linear and angular spin currents inside the superconductor are derived. We demonstrate that the electric field induced by super spin current is equal to the one induced by equivalent charge obtained from the second Ginzburg-Landau-type equation, which shows self-consistency of our theory. By applying these Ginzburg-Landau-type equations, the effect of electric field on the superconductor is also studied. These results will help us get a better understanding of the spin superconductor and the related topics such as Bose-Einstein condensate of magnons and spin superfluidity., Comment: 9 pages, 5 figures

The search for long electron phase coherence length, which is the length that an electron can keep its quantum wave-like properties, has attracted considerable interest in the last several decades. Here, we report the long phase coherence length of ~ 3.7 micro meters in La-doped CdO thin films at 2 K. Systematical investigations of the La doping and the temperature dependences of the electron mobility and the electron phase coherence length reveal contrasting scattering mechanisms for these two physical properties. Furthermore, these results show that the oxygen vacancies could be the dominant scatters in CdO thin films that break the electron phase coherence, which would shed light on further investigation of phase coherence properties in oxide materials., Comment: 13 pages, 6 figure. SI: 8 pages. To appear in Phys. Rev. B

Recently, entropy corrections on nonorientable manifolds such as the Klein bottle are proposed as a universal characterization of critical systems with an emergent conformal field theory (CFT). We show that entropy correction on the Klein bottle can be interpreted as a boundary effect via transforming the Klein bottle into an orientable manifold with nonlocal boundary interactions. The interpretation reveals the conceptual connection of the Klein bottle entropy with the celebrated Affleck-Ludwig entropy in boundary CFT. We propose a generic scheme to extract these universal boundary entropies from quantum Monte Carlo calculation of partition function ratios in lattice models. Our numerical results on the Affleck-Ludwig entropy and Klein bottle entropy for the $q$-state quantum Potts chains with $q=2,3$ show excellent agreement with the CFT predictions. For the quantum Potts chain with $q=4$, the Klein bottle entropy slightly deviates from the CFT prediction, which is possibly due to marginally irrelevant terms in the low-energy effective theory., Comment: 10 pages, 4 figures. Published version

Objectives Chemoresistance development represents a major obstacle to the successful treatment of colorectal cancer (CRC). The aim of this study was to elucidate the mechanism by which miR-506 reverses oxaliplatin chemoresistance in CRC. Methods In this study, miR-506 levels were measured in 74 patients with colon cancer via quantitative real-time polymerase chain reaction (qRT-PCR) and in situ hybridization (ISH). We subsequently analysed the relationship between miR-506 expression and CRC patient survival via the Kaplan-Meier method. MTT assay demonstrated the fractional survival rates and cell viability of HCT116-OxR, HCT116-OxR-miR-Ctrl and HCT116-OxR-miR-506 cells treated with oxaliplatin at different concentrations. Cell proliferation and apoptosis were assessed via flow cytometry (FCM) analysis and apoptosis assay. MDR1 mRNA expression and P-gp protein expression were assessed via qRT-PCR and Western blotting (WB) respectively. Immunofluorescence (IF) staining demonstrated P-gp expression in HCT116-OxR and HCT116-OxR-miR-506 cells. qRT-PCR and WB were used to detect Wnt/β-catenin pathway activity after miR-506 overexpression. Results In the present study, in ISH and qRT-PCR results demonstrated that miR-506 is weakly expressed in chemoresistant CRC tissues. The low miR-506 expression group exhibited lower 5-year OS and lower 5-year RFS than the high miR-506 expression group. miR-506 overexpression inhibited cell growth and increased oxaliplatin-induced cell apoptosis in HCT116-OxR cells, as shown via FCM and apoptosis assay. We subsequently noted low MDR1/P-gp expression in HCT116-OxR-miR-506 cells via qRT-PCR, WB and IF. Lastly, we demonstrated low MDR1/P-gp expression in HCT116-OxR-miR-506 cells via inhibition of the Wnt/β-catenin by WB, MTT and FCM analysis. Conclusion Taken together, the findings of our study demonstrate that miR-506 overexpression in HCT116-OxR cells enhances oxaliplatin sensitivity by inhibiting MDR1/P-gp expression via down-regulation of the Wnt/β-catenin pathway and thus provide a rationale for the development of miRNA-based strategies to reverse oxaliplatin resistance in CRC cells.

Recently, chiral-induced spin selectivity has been attracting intense interest. Here, we report a theoretical study of spin-dependent electron transport in achiral nanotubes contacted by nonmagnetic leads. Our results reveal that by properly connecting to the leads, the achiral nanotubes can present a pronounced spin filtering phenomenon even if the spin-orbit coupling is very weak. In addition, the spin selectivity effect holds for various achiral nanotubes with different radii and is still significant in the presence of strong disorder and dephasing. These findings open new opportunities of using achiral molecules in spintronic applications and could motivate further studies on spin transport along achiral systems.

Regulatory factor X-5 (RFX5) was previously characterized as an essential and highly specific regulator of major histocompatibility class II (MHCII) gene expression in the immune system. We found that RFX5 is significantly upregulated in hepatocellular carcinoma (HCC) tumors and cell lines compared with non-tumor tissues in mRNA expression levels, but it fails to induce the expression of MHCII. However, RFX5 can strongly bind to the tripeptidyl peptidase 1 (TPP1) promoter region and then increase its transcriptional activity. We also found that manipulation the expression of RFX5 can significantly affect the expression of TPP1 in HepG2, which suggested that RFX5 can transcriptionally activate TPP1 in HCC. Moreover, TPP1 is overexpressed in HCC tissues and significantly correlated with poor prognosis of HCC patients, suggesting that it may have potential biological implications in HCC.

The effect of magnetic field on an ultrathin magnetic topological insulator film with structural inversion asymmetry is investigated. We introduce the phase diagram, calculate the Landau level spectrum analytically, and simulate the transport behavior in Landauer-Buttiker formalism. The quantum anomalous Hall phase will survive increasing magnetic field. Due to the two spin-polarized zero modes of Landau levels, a nontrivial phase similar with the quantum spin Hall effect can be induced by a magnetic field, which is protected by structural inversion symmetry. Some exotic longitudinal and Hall resistance plateaus with fractional values are also found in a six-terminal Hall bar, arising from the coupling between edge states due to an inverted energy band and Landau levels.

The Higgs amplitude mode in superconductors is the condensed matter analogy of Higgs bosons in particle physics. We investigate the time evolution of Higgs amplitude mode in massless Dirac systems, induced by a weak quench of an attractive interaction. We find that the Higgs amplitude mode in the half-filling honeycomb lattice has a logarithmic decaying behaviour, qualitatively different from the $1/\sqrt{t}$ decay in the normal superconductors. Our study is also extended to the doped cases in honeycomb lattice. As for the 3D Dirac semimetal at half filling, we obtain an undamped oscillation of the amplitude mode. Our finding is not only an important supplement to the previous theoretical studies on normal fermion systems, but also provide an experimental signature to characterize the superconductivity in 2D or 3D Dirac systems., 6 pages, 8 figures

The behavior of phase coherence is studied in two-dimensional hole gas through the integer quantum Hall plateau-to-plateau transition. From the plateau transition as a function of temperature, scaling properties of multiple transitions are analyzed. Our results are in good agreement with the assumption of the zero-point fluctuations of the coherent holes, and support the intrinsic saturation of the coherence time at low temperature limit. The critical exponent $p$ can also be determined under the scheme of the zero-point fluctuations. The similarity and difference in experimental observations between quantum Griffiths singularity and plateau transition is discussed. The spin-orbit coupling effect's influence on the plateau transition is explored by comparing the results from different transitions.

Recent experiments find the signal of giant nonlocal resistance $R_{NL}$ in H-shaped graphene samples due to the spin/valley Hall effect. Interestingly, when the Fermi energy deviates from the Dirac point, $R_{NL}$ decreases to zero much more rapidly compared with the local resistance $R_L$, and the well-known relation of $R_{NL}\propto R_L^3$ is not satisfied. In this work, based on the non-equilibrium Green's function method, we explain such transport phenomena in the H-shaped graphene with Rashba spin-orbit coupling. When the Fermi energy is near the Dirac point, the nonlocal resistance is considerably large and is much sharper than the local one. Moreover, the relationship between the Rashba effect and the fast decay of $R_{NL}$ compared with $R_L$ is further investigated. We find that the Rashba effect does not contribute not only to the fast decay but also to the peak of $R_{NL}$ itself. Actually, it is the extremely small density of states near the Dirac point that leads to the large peak of $R_{NL}$, while the fast decay results from the quasi-ballistic mechanism. Finally, we revise the classic formula $R_{NL}\propto R_L^3$ by replacing $R_{NL}$ with $R_{Hall}$, which represents the nonlocal resistance merely caused by the spin Hall effect, and the relation holds well., Comment: 7 pages, 5 figures