Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 37
Filtrar
Mais filtros

Assunto principal
Tipo de estudo
Idioma
Intervalo de ano de publicação
1.
Nat Mater ; 2023 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-36894771

##### RESUMO

The lowest-lying fundamental excitation of an incommensurate charge-density-wave material is believed to be a massless phason-a collective modulation of the phase of the charge-density-wave order parameter. However, long-range Coulomb interactions should push the phason energy up to the plasma energy of the charge-density-wave condensate, resulting in a massive phason and fully gapped spectrum1. Using time-domain terahertz emission spectroscopy, we investigate this issue in (TaSe4)2I, a quasi-one-dimensional charge-density-wave insulator. On transient photoexcitation at low temperatures, we find the material strikingly emits coherent, narrowband terahertz radiation. The frequency, polarization and temperature dependences of the emitted radiation imply the existence of a phason that acquires mass by coupling to long-range Coulomb interactions. Our observations underscore the role of long-range interactions in determining the nature of collective excitations in materials with modulated charge or spin order.

2.
Nat Commun ; 14(1): 720, 2023 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-36759623

##### RESUMO

While chirality imbalances are forbidden in conventional lattice systems, non-Hermiticity can effectively avoid the chiral-doubling theorem to facilitate 1D chiral dynamics. Indeed, such systems support unbalanced unidirectional flows that can lead to the localization of an extensive number of states at the boundary, known as the non-Hermitian skin effect (NHSE). Recently, a generalized (rank-2) chirality describing a 2D robust gapless mode with dispersion ω = kxky has been introduced in crystalline systems. Here we demonstrate that rank-2 chirality imbalances can be established in a non-Hermitian (NH) lattice system leading to momentum-resolved chiral dynamics, and a rank-2 NHSE where there are both edge- and corner-localized skin modes. We then experimentally test this phenomenology in a 2-dimensional topolectric circuit that implements a NH Hamiltonian with a long-lived rank-2 chiral mode. Using impedance measurements, we confirm the rank-2 NHSE in this system, and its manifestation in the predicted skin modes and a highly unusual momentum-position locking response. Our investigation demonstrates a circuit-based path to exploring higher-rank chiral physics, with potential applications in systems where momentum resolution is necessary, e.g., in beamformers and non-reciprocal devices.

3.
Chin J Integr Med ; 2022 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-36401751

##### RESUMO

OBJECTIVE: To observe the effects of Guizhi Fuling Capsule (GZFLC) on myeloma cells and explore the mechanisms. METHODS: MM1S and RPMI 8226 cells were co-cultured with different concentrations of serum and the cell experiments were divided into negative (10%, 20% and 40%) groups, GZFLC (10%, 20%, and 40%) groups and a control group. Cell counting kit-8 (CCK-8) assays and flow cytometry were used to detect the viability and apoptosis levels of myeloma cells. The effects on mitochondria were examined by reactive oxygen specie (ROS) and tetrechloro-tetraethylbenzimidazol carbocyanine iodide (JC-1) assays. Western blot was used to detect the expression of B cell lymphoma-2 (Bcl-2), Bcl-2-associated X (Bax), cleaved caspase-3, -9, cytochrome C (Cytc) and apoptotic protease-activating factor 1 (Apaf-1). RPMI 8226 cells (2 × 107) were subcutaneously inoculated into 48 nude mice to study the in vivo antitumor effects of GZFLC. The mice were randomly divided into four groups using a completely randomized design, the high-, medium-, or low-dose GZFLC (840, 420, or 210 mg/kg per day, respectively) or an equal volume of distilled water, administered daily for 15 days. The tumor volume changes in and survival times of the mice in the GZFLC-administered groups and a control group were observed. Cytc and Apaf-1 expression levels were detected by immunohistochemistry. RESULTS: GZFLC drug serum decreased the viability and increased the apoptosis of myeloam cells (P<0.05). In addition, this drug increased the ROS levels and decreased the mitochondrial membrane potential (P<0.01). Western blot showed that the Bcl-2/Bax ratios were decreased in the GZFLC drug serum-treated groups, whereas the expression levels of cleaved caspase-3, -9, Cytc and Apaf-1 were increased (all P<0.01). Over time, the myeloma tumor volumes of the mice in the GZFLC-administered groups decreased, and survival time of the mice in the GZFLC-administered groups were longer than that of the mice in the control group. Immunohistochemical analysis of tumor tissues from the mice in the GZFLC-administered groups revealed that the Cytc and Apaf-1 expression levels were increased (P<0.05). CONCLUSION: GZFLC promoted apoptosis of myeloma cells through the mitochondrial apoptosis pathway and significantly reduced the tumor volumes in mice with myeloma, which prolonged the survival times of the mice.

4.
Int J Gen Med ; 15: 2347-2360, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35264873

##### RESUMO

Background: This study aimed to identify significant genes associated with cutaneous squamous cell carcinoma (CSCC) initiation and development. Methods: The overlapped differential expressed genes (DEGs) between normal and CSCC samples were firstly screened out, followed by KEGG analysis. The top 10 hub genes were then detected from the whole protein-protein interaction (PPI) network. Further, important biomarkers continuously associated with actinic keratosis (AK), CSCC, and CSCC invasion was successively filtrated. GSEA analysis was finally performed to reveal potential mechanisms associated with biomarkers. Results: A total of 179 DEGs were identified, which were enriched in pathways in cancer, PI3K-Akt signaling pathway, and human papillomavirus infection. The 10 hub genes were firstly identified from the PPI network, and they were all highly expressed in AK tissues compared with normal tissues. Next, we found that 6 genes were overexpressed in CSCC compared with AK tissues. Further, we identified that the expression of 2 genes (MYBL2 and TK1) was higher in CSCC invasion groups compared with samples without invasion. Through a series of filtrations, we confirmed that MYBL2 and TK1 were the most significant biomarkers associated with CSCC initiation and progression. The pan-cancer analysis further supported their prognostic value in human cancers. GSEA analysis found that they positively correlated with N glycan biosynthesis and p53 signaling pathways. Conclusion: MYBL2 and TK1 were proved to play a vital role in CSCC tumorigenesis and progression, which may act as promising biomarkers or therapeutic targets for accurate diagnosis and treatment of CSCC.

5.
Phys Rev Lett ; 127(6): 066401, 2021 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-34420349

##### RESUMO

We study the geometric response of three-dimensional non-Hermitian crystalline systems with nontrivial point-gap topology. For systems with fourfold rotation symmetry, we show that in the presence of disclination lines with a total Frank angle, which is an integer multiple of 2π, there can be nontrivial one-dimensional point-gap topology along the direction of the disclination lines. This results in disclination-induced non-Hermitian skin effects. By doubling a non-Hermitian Hamiltonian to a Hermitian three-dimensional chiral topological insulator, we show that the disclination-induced skin modes are zero modes of the effective surface Dirac fermion(s) in the presence of a pseudomagnetic flux induced by disclinations. Furthermore, we find that our results have a field theoretic description, and the corresponding geometric response actions (e.g., the Euclidean Wen-Zee action) enrich the topological field theory of non-Hermitian systems.

6.
Front Endocrinol (Lausanne) ; 12: 705499, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34421823

##### RESUMO

Breast cancer and osteoporosis are common diseases that affect the survival and quality of life in postmenopausal women. Women with breast cancer are more likely to develop osteoporosis than women without breast cancer due to certain factors that can affect both diseases simultaneously. For instance, estrogen and the receptor activator of nuclear factor-κB ligand (RANKL) play important roles in the occurrence and development of these two diseases. Moreover, chemotherapy and hormone therapy administered to breast cancer patients also increase the incidence of osteoporosis, and in recent years, neuropeptide Y (NPY) has also been found to impact breast cancer and osteoporosis.Y1 and Y5 receptors are highly expressed in breast cancer, and Y1 and Y2 receptors affect osteogenic response, thus potentially highlighting a potential new direction for treatment strategies. In this paper, the relationship between breast cancer and osteoporosis, the influence of NPY on both diseases, and the recent progress in the research and treatment of these diseases are reviewed.

##### Assuntos
Neoplasias da Mama/patologia , Neuropeptídeo Y/metabolismo , Osteoporose/patologia , Receptores de Neuropeptídeo Y/metabolismo , Neoplasias da Mama/metabolismo , Feminino , Humanos , Osteoporose/metabolismo , Prognóstico
7.
Phys Rev Lett ; 126(23): 233402, 2021 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-34170160

##### RESUMO

The modulation and engineering of the free-electron wave function bring new ingredients to the electron-matter interaction. We consider the dynamics of a free-electron passing by a two-level system fully quantum mechanically and study the enhancement of interaction from the modulation of the free-electron wave function. In the presence of resonant modulation of the free-electron wave function, we show that the electron energy loss and gain spectrum is greatly enhanced for a coherent initial state of the two-level system. Thus, a modulated electron can function as a probe of the atomic coherence. We further find that distantly separated two-level atoms can be entangled through interacting with the same free electron. Effects of modulation-induced enhancement can also be observed using a dilute beam of modulated electrons.

8.
Phys Chem Chem Phys ; 23(22): 12679-12691, 2021 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-34036996

##### RESUMO

High-performance organic semiconductor materials based on the small aromatic anthracene-core and its derivatives develop comparatively slowly due to the lack of a profound understanding of the influence of chemical modifications on their charge-transfer properties. Herein, the electronic properties and the charge transport characteristics of several typical anthracene-based derivatives with aryl groups substituted at the 2,6-site are systematically investigated by multi-scale simulation methods including Molecular Dynamics (MD) simulation and the full quantum nuclear tunneling model in the framework of density functional theory (DFT). To elucidate the origin of different charge transport properties of these anthracene-based materials, analysis of the molecular stacking and noncovalent intermolecular interaction caused by different substituents was carried out. The results indicate that the electron and hole injection capabilities and the air oxidation stability of the anthracene derivatives are greatly improved when the size of the aryl substituent increases. In addition, the incorporation of 2,6-site aryl substituents can inhibit the stretching vibration of the anthracene-core during charge transport, and allow molecular packing along the long axis (a-axis of DPA and BDBFAnt, and c-axis of dNaAnt) with almost no slippage, and the main transport channels remain unchanged, exhibiting more isotropic 2D transport properties. It should be emphasized that the edge-to-face dimers with smallest dihedral angles are closest to the thermally stable dimer model, with relatively larger π-orbital distributions in transmission channels (dimer 1, 2) and the largest spatial overlap, resulting in the largest hole transfer integral in DPA (Vh1/h2 = 57 meV). Although the analysis of the thermal disorder effect shows a phonon scattering effect, the maximum hole mobility of the DPA molecule is still as high as 1.5 cm2 V-1 s-1.

9.
RSC Adv ; 11(11): 5947-5957, 2021 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-35423155

##### RESUMO

The exploitation of efficient hydrogen evolution reaction (HER) electrocatalysts has become increasingly urgent and imperative; however, it is also challenging for high-performance sustainable clean energy applications. Herein, novel Co9S8 nanoparticles embedded in a porous N,S-dual doped carbon composite (abbr. Co9S8@NS-C-900) were fabricated by the pyrolysis of a single crystal Co-MOF assisted with thiourea. Due to the synergistic benefit of combining Co9S8 nanoparticles with N,S-dual doped carbon, the composite showed efficient HER electrocatalytic activities and long-term durability in an alkaline solution. It shows a small overpotential of -86.4 mV at a current density of 10.0 mA cm-2, a small Tafel slope of 81.1 mV dec-1, and a large exchange current density (J 0) of 0.40 mA cm-2, which are comparable to those of Pt/C. More importantly, due to the protection of Co9S8 nanoparticles by the N,S-dual doped carbon shell, the Co9S8@NS-C-900 catalyst displays excellent long-term durability. There is almost no decay in HER activities after 1000 potential cycles or it retains 99.5% of the initial current after 48 h.

10.
Front Med (Lausanne) ; 8: 746909, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34631758

##### RESUMO

Dedifferentiated central chondrosarcoma (DCCS) is a rare cartilage tumor with invasive biological behavior and a poor prognosis. To better understand the morphological characteristics of this type of tumor and its internal mechanism of dedifferentiation, we retrospectively analyzed 57 cases of DCCS. A total of 29 female and 28 male patients were included, ranging in age from 20 to 76 years, with a median age of 54 years. Fifty-seven cases of DCCS occurred in the pelvis (n = 29), femur (n = 17), scapula (n = 4), tibia (n = 2), humerus (n = 2), metatarsals (n = 1), fibula (n = 1), and radius (n = 1). Radiologically, DCCS had two different appearances on imaging, with an area showing calcifications of the cartilage forming the tumor juxtaposed to a lytic area with a highly aggressive, non-cartilaginous component. Histopathologically, the distinctive morphological features consisted of two kinds of defined components: a well-differentiated cartilaginous tumor and non-cartilaginous sarcoma. The cartilaginous components included grade 1 (n = 38; 66.7%) and grade 2 (n = 19; 33.3%) cartilage. The sarcoma components included those of osteosarcoma (n = 29; 50.9%), undifferentiated pleomorphic sarcoma (n = 20; 35.1%), rhabdomyosarcoma (n = 3; 5.2%), fibrosarcoma (n = 2; 3.5%), spindle cell sarcoma (n = 2; 3.5%) and angiosarcoma (n = 1; 1.8%). Immunohistochemistry showed that the expression of p53 and RB in the sarcoma components was significantly higher than that in the cartilaginous components, suggesting that these factors play roles in the dedifferentiation process of chondrosarcoma. DCCS is a highly malignant tumor with a poor prognosis. Except for the patients who were lost to follow-up, most of our patients died.

11.
Mitochondrial DNA B Resour ; 5(2): 1236-1237, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33366924

##### RESUMO

We first reported the mitochondrial genome of Centropus bengalensis. The mitogenome of C. bengalensis contains 17,117 base pairs. The overall base composition of complete mitogenome is 28.15% A, 27.95% T, 21.86% C, and 22.04% G, with 43.90% of the GC content. All genes exhibit the typical mitochondrial gene arrangement and transcribing directions. Phylogenetic analysis of 4 Centropus species was performed based on the sequence of cytochrome b gene using the neighbor-joining method and the Kimura 2-parameter model in MEGA 7.0.

12.
Phys Rev Lett ; 125(3): 033603, 2020 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-32745404

##### RESUMO

We demonstrate a non-Hermitian topological effect that is characterized by having complex eigenvalues only in the edge states of a topological material, despite the fact that the material is completely uniform. Such an effect can be constructed in any topological structure formed by two gapped subsystems, e.g., a quantum spin-Hall system, with a suitable non-Hermitian coupling between the spins. The resulting complex-eigenvalued edge state is robust against defects due to the topological protection. In photonics, such an effect can be used for the implementation of topological lasers, in which a uniform pumping provides gain only in the edge lasing state. Furthermore, such a topological lasing model is reciprocal and is thus compatible with standard photonic platforms.

13.
Phys Rev Lett ; 124(16): 167601, 2020 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-32383931

##### RESUMO

In the context of recent experimental observations of an unexpectedly large thermal Hall conductivity, κ_{H}, in insulating La_{2}CuO_{4} (LCO) and SrTiO_{3} (STO), we theoretically explore conditions under which acoustic phonons can give rise to such a large κ_{H}. Both the intrinsic and extrinsic contributions to κ_{H} are large in proportion to the dielectric constant, Îµ, and the "flexoelectric" coupling, F. While the intrinsic contribution is still orders of magnitude smaller than the observed effect, an extrinsic contribution proportional to the phonon mean-free path appears likely to account for the observations, at least in STO. We predict a larger intrinsic κ_{H} in certain insulating perovskites.

14.
Zhongguo Shi Yan Xue Ye Xue Za Zhi ; 28(2): 713-716, 2020 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-32319423

##### RESUMO

It is found that non-coding RNAs (ncRNA) plays an important role in the development and treatment of multiple myeloma (MM). For example, some microRNAs (miRNAs) can regulate gene expression, affect autophagy, apoptosis and other physiological and pathological processes, affect synthesis of protein, etc., thus providing a basis for diagnosis, treatment and prognosis of MM evaluation. Long-chain non-coding RNA (Long noncoding RNA, lncRNA) can participate in cell differentiation, bind transcription factors to modify histones, specifically regulate the genome, etc., thus providing potential therapeutic targets for MM patients. While circular RNA (CircRNA) possesses post-transcriptional regulation on function and gene expression, thereby inhibiting the cell activity and proliferation of MM, further inducing apoptosis. In this reviews the functional characteristics of different non-coding RNAs and their research progress in multiple myeloma are summarized briefly.

##### Assuntos
Mieloma Múltiplo , Regulação da Expressão Gênica , Humanos , MicroRNAs , RNA Circular , RNA Longo não Codificante
15.
Dalton Trans ; 49(13): 4060-4066, 2020 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-32129379

##### RESUMO

Herein we report a new 4-fold interpenetrated metal-organic framework (MOF) functionalized with O- groups for selective Th(iv) capture, the activated samples 1a exhibited a high adsorption capacity for pure Th(iv) ions (Kd = 3.16 × 105 mL g-1) and the amount of metal ions adsorbed on the adsorbent was 165.61 mg g-1. A high removal efficiency of 99.75% was achieved within 10 min with an initial Th(iv) concentration of 100 mg L-1 and the adsorption data followed the pseudo-second-order model. In addition, the separation coefficient (S) of Th(iv) to metal ions with different valence states such as Th(iv)/La(iii), Th(iv)/Sm(iii), Th(iv)/Ho(iii), Th(iv)/Cd(ii) and Th(iv)/K(i) achieved values of 19.66, 26.83, 16.90, 11.26 and 255.79, respectively. Even given the fact that MOFs with O- groups showed high affinity for Pb(ii) ions, our adsorption studies for compound 1a revealed a separation coefficient (STh(IV)/Pb(II)) of 4.36. Further, the adsorption of Th(iv) ions to compound 1a was investigated by FT-IR, SEM-EDS and XPS.

16.
Exp Ther Med ; 17(5): 3441-3450, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30988723

##### RESUMO

The aim of the current study was to investigate the underlying mechanism of S-phase kinase associated protein 2 (Skp2) gene inhibition by lentivirus-mediated RNA interference (RNAi) on the cell cycle, apoptosis and proliferation of endometrial carcinoma HEC-1-A cells. A lentivirus shRNA vector targeting Skp2 was constructed and transfected into HEC-1-A cells. HEC-1-A cells transfected with a scramble sequence were used as negative controls. The mRNA and protein expression of Skp2, p27, cyclin D1 and caspase-3 were detected via reverse transcription-quantitative polymerase chain reaction and western blotting, respectively. The effects of Skp2 inhibition on the cell cycle, apoptosis and proliferation of HEC-1-A cells were detected using flow cytometry and a cell counting kit-8. Skp2 co-expression data was analyzed using Oncomine and TCGA databases. The positive recombinant viral clones were identified via PCR and confirmed via sequencing. The mRNA and protein expression of Skp2 were significantly decreased in HEC-1-A cells transfected with the lentiviral vectors compared with the negative control. In addition, there were no significant changes in the mRNA expression of p27 and cyclin D1; however, the protein levels of p27 and cyclin D1 were upregulated and downregulated, respectively, in HEC-1-A cells transfected with lentiviral vectors compared with negative controls. RNAi-induced Skp2 inhibition exerted an anti-proliferative effect by inducing cell cycle arrest, however cell apoptosis was not significantly affected. In the TCGA database, Skp2 expression positively associated with IGF2R, IGF2BP3, IGFBP1 and CCNF, while Skp2 expression negatively associated with IGF2, IGFBP6, IGFBP7 and IGFBP3. RNAi-induced Skp2 inhibition upregulated the protein expression of p27 and downregulated the protein expression of cyclin D1. The expression of Skp2 in endometrial cancer may therefore be regulated by the insulin-like growth factor 1 receptor signaling pathway.

17.
Dalton Trans ; 48(21): 7080-7084, 2019 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-30816369

##### RESUMO

Herein, we fabricated a hybrid PDVB-Ln4L4 metallopolymer using a vinyl functionalized lanthanide-organic tetrahedral cage as the cross-linking agent. Such a covalent embedding strategy not only tunes the morphology and porosity of the metallopolymer, but also improves the luminescence property of the lanthanide organic polyhedron. Potential application in lanthanide separation has also been demonstrated. This study provides a potential strategy for the immobilization of multinuclear lanthanide-organic edifices toward heterogeneous application.

18.
Poult Sci ; 98(1): 136-149, 2019 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-30107611

##### RESUMO

Aflatoxin B1 (AFB1) is very harmful for broiler production and public health. The water-soluble castoff in gluten production, i.e., the water-soluble substances of wheat (WSW) that contains 14% pentosan has positive effect on animal nutrient absorption, immunity, and antioxidation. Our study aims to investigate the preventive effects of WSW against AFB1-induced broiler liver injury. One day-old Arbor Acres broilers were randomly separated to 4 groups and were, respectively, fed with control diet, diet with 5 mg/kg AFB1 standard, diet with 5 mg/kg AFB1 standard and 214 ml/kg WSW, and diet with 214 ml/kg WSW continuously for 28 d. The histopathological, ultra-structural, and serological changes were tested to evaluate liver damage. The hallmarks of hepatocellular autophagy, apoptosis, and inflammation were measured by Western Blot and real-time polymerase chain reaction. The content of AFB1 in chicken liver was detected with an ultra-high performance liquid chromatography linked with the fluorescence detection method. The results showed that (i) WSW restored AFB1-induced changes in serum biochemical parameters, and ameliorated histomorphological changes in hepatocytes, (ii) WSW reduced the content of AFB1 in chicken liver, (iii) WSW alleviated AFB1-induced autophagy inhibition by up-regulating hepatic LC3, beclin-1, and down-regulating hepatic mTOR and cytoplasmic P53 expressions, (iv) WSW alleviated AFB1-induced hepatocellular apoptosis via inhibiting pro-apoptotic gene expression (nuclear P53, Caspase3, Bax), and promoting anti-apoptotic gene expression (bcl-2), (v) WSW feeding ameliorated AFB1-induced liver inflammation via impeding TLR4/NF-${{\bf \kappa }}$B and IL-1/NF-${{\bf \kappa }}$B signaling pathways, down-regulating pro-inflammatory cytokines (IL-1${{\bf \beta }}$, IL-6, and IL-8), and markedly up-regulating anti-inflammatory genes (IL-10 and HO-1). Conclusively, WSW is a potential preventer of AFB1-induced broiler liver damage by reducing the AFB1 content in liver, accelerating hepatocellular autophagy and inhibiting hepatocytes apoptosis and liver inflammation.

##### Assuntos
Aflatoxina B1/toxicidade , Doença Hepática Induzida por Substâncias e Drogas/prevenção & controle , Doença Hepática Induzida por Substâncias e Drogas/veterinária , Poliéster Sulfúrico de Pentosana/farmacologia , Substâncias Protetoras/farmacologia , Triticum/química , Animais , Apoptose/efeitos dos fármacos , Autofagia/efeitos dos fármacos , Galinhas , Hepatócitos/efeitos dos fármacos , Inflamação/genética , Inflamação/metabolismo , Fígado/efeitos dos fármacos , Fígado/enzimologia , Fígado/patologia
19.
Phys Rev Lett ; 121(19): 196401, 2018 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-30468621

##### RESUMO

We show that the Nielsen-Ninomiya no-go theorem still holds on a Floquet lattice: there is an equal number of right-handed and left-handed Weyl points in a three-dimensional Floquet lattice. However, in the adiabatic limit, where the time evolution of the low-energy subspace is decoupled from the high-energy subspace, we show that the bulk dynamics in the low-energy subspace can be described by Floquet bands with extra left- or right-handed Weyl points, despite the no-go theorem. Assuming adiabatic evolution of two bands, we show that the difference of the number of right-handed and left-handed Weyl points equals twice the winding number of the adiabatic Floquet operator over the Brillouin zone. Based on these findings, we propose a realization of purely left- or right-handed Weyl particles on a 3D lattice using a Hamiltonian obtained through dimensional reduction of a four-dimensional quantum Hall system. We argue that the breakdown of the adiabatic approximation on the surface facilitates unusual closed orbits of wave packets in an applied magnetic field, which traverse alternatively through the low-energy and high-energy sector of the spectrum.

20.
Proc Natl Acad Sci U S A ; 115(43): 10938-10942, 2018 10 23.
Artigo em Inglês | MEDLINE | ID: mdl-30297431

##### RESUMO

The chiral Majorana fermion is a massless self-conjugate fermion which can arise as the edge state of certain 2D topological matters. It has been theoretically predicted and experimentally observed in a hybrid device of a quantum anomalous Hall insulator and a conventional superconductor. Its closely related cousin, the Majorana zero mode in the bulk of the corresponding topological matter, is known to be applicable in topological quantum computations. Here we show that the propagation of chiral Majorana fermions leads to the same unitary transformation as that in the braiding of Majorana zero modes and propose a platform to perform quantum computation with chiral Majorana fermions. A Corbino ring junction of the hybrid device can use quantum coherent chiral Majorana fermions to implement the Hadamard gate and the phase gate, and the junction conductance yields a natural readout for the qubit state.

...