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1.
Mol Cell ; 65(2): 296-309, 2017 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-28065600

RESUMO

In mammalian cells, histone deacetylase (HDAC) and Sirtuin (SIRT) are two families responsible for removing acetyl groups from acetylated proteins. Here, we describe protein deacetylation coupled with deacetylimination as a function of lysyl oxidase (LOX) family members. LOX-like 3 (Loxl3) associates with Stat3 in the nucleus to deacetylate and deacetyliminate Stat3 on multiple acetyl-lysine sites. Surprisingly, Loxl3 N-terminal scavenger receptor cysteine-rich (SRCR) repeats, rather than the C-terminal oxidase catalytic domain, represent the major deacetylase/deacetyliminase activity. Loxl3-mediated deacetylation/deacetylimination disrupts Stat3 dimerization, abolishes Stat3 transcription activity, and restricts cell proliferation. In Loxl3-/- mice, Stat3 is constitutively acetylated and naive CD4+ T cells are potentiated in Th17/Treg cell differentiation. When overexpressed, the SRCR repeats from other LOX family members can catalyze protein deacetylation/deacetylimination. Thus, our findings delineate a hitherto-unknown mechanism of protein deacetylation and deacetylimination catalyzed by lysyl oxidases.


Assuntos
Aminoácido Oxirredutases/metabolismo , Linfócitos T CD4-Positivos/enzimologia , Colite/enzimologia , Processamento de Proteína Pós-Traducional , Fator de Transcrição STAT3/metabolismo , Acetilação , Aminoácido Oxirredutases/deficiência , Aminoácido Oxirredutases/genética , Animais , Linfócitos T CD4-Positivos/imunologia , Catálise , Diferenciação Celular , Núcleo Celular/enzimologia , Proliferação de Células , Colite/genética , Colite/imunologia , Modelos Animais de Doenças , Genótipo , Células HEK293 , Células HeLa , Humanos , Células MCF-7 , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fenótipo , Domínios Proteicos , Multimerização Proteica , Interferência de RNA , Fator de Transcrição STAT3/genética , Linfócitos T Reguladores/enzimologia , Linfócitos T Reguladores/imunologia , Células Th17/enzimologia , Células Th17/imunologia , Transcrição Gênica , Transfecção
2.
Am J Transplant ; 2024 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-38642712

RESUMO

Immune checkpoint inhibitors (ICIs) as a downstaging or bridging therapy for liver transplantation (LT) in hepatocellular carcinoma patients are rapidly increasing. However, the evidence about the feasibility and safety of pre-LT ICI therapy is limited and controversial. To this end, a multicenter, retrospective cohort study was conducted in 11 Chinese centers. The results showed that 83 recipients received pre-LT ICI therapy during the study period. The median post-LT follow-up was 8.1 (interquartile range 3.3-14.6) months. During the short follow-up, 23 (27.7%) recipients developed allograft rejection, and 7 of them (30.4%) were diagnosed by liver biopsy. Multivariate logistics regression analysis showed that the time interval between the last administration of ICI therapy and LT (TLAT) ≥ 30 days was an independent protective factor for allograft rejection (odds ratio = 0.096, 95% confidence interval 0.026-0.357; P < .001). Multivariate Cox analysis showed that allograft rejection was an independent risk factor for overall survival (hazard ratio = 9.960, 95% confidence interval 1.006-98.610; P = .043). We conclude that patients who receive a pre-LT ICI therapy with a TLAT shorter than 30 days have a much higher risk of allograft rejection than those with a TLAT longer than 30 days. The presence of rejection episodes might be associated with higher post-LT mortality.

3.
Anal Chem ; 96(2): 847-855, 2024 01 16.
Artigo em Inglês | MEDLINE | ID: mdl-38159051

RESUMO

RNA molecules undergo various chemical modifications that play critical roles in a wide range of biological processes. N6,N6-Dimethyladenosine (m6,6A) is a conserved RNA modification and is essential for the processing of rRNA. To gain a deeper understanding of the functions of m6,6A, site-specific and accurate quantification of this modification in RNA is indispensable. In this study, we developed an AlkB-facilitated demethylation (AD-m6,6A) method for the site-specific detection and quantification of m6,6A in RNA. The N6,N6-dimethyl groups in m6,6A can cause reverse transcription to stall at the m6,6A site, resulting in truncated cDNA. However, we found that Escherichia coli AlkB demethylase can effectively demethylate m6,6A in RNA, generating full-length cDNA from AlkB-treated RNA. By quantifying the amount of full-length cDNA produced using quantitative real-time PCR, we were able to achieve site-specific detection and quantification of m6,6A in RNA. Using the AD-m6,6A method, we successfully detected and quantified m6,6A at position 1851 of 18S rRNA and position 937 of mitochondrial 12S rRNA in human cells. Additionally, we found that the level of m6,6A at position 1007 of mitochondrial 12S rRNA was significantly reduced in lung tissues from sleep-deprived mice compared with control mice. Overall, the AD-m6,6A method provides a valuable tool for easy, accurate, quantitative, and site-specific detection of m6,6A in RNA, which can aid in uncovering the functions of m6,6A in human diseases.


Assuntos
Proteínas de Escherichia coli , RNA , Humanos , Animais , Camundongos , RNA/química , Adenosina/química , DNA Complementar , Metilação , Escherichia coli/genética , Escherichia coli/metabolismo , Desmetilação , Oxigenases de Função Mista
4.
Anal Chem ; 96(11): 4726-4735, 2024 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-38450632

RESUMO

DNA cytosine methylation (5-methylcytosine, 5mC) is a predominant epigenetic modification that plays a critical role in a variety of biological and pathological processes in mammals. In active DNA demethylation, the 10-11 translocation (TET) dioxygenases can sequentially oxidize 5mC to generate three modified forms of cytosine, 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC), and 5-carboxylcytosine (5caC). Beyond being a demethylation intermediate, recent studies have shown that 5fC has regulatory functions in gene expression and chromatin organization. While some methods have been developed to detect 5fC, genome-wide mapping of 5fC at base resolution is still highly desirable. Herein, we propose a chemical labeling enrichment and deamination sequencing (CLED-seq) method for detecting 5fC in genomic DNA at single-base resolution. The CLED-seq method utilizes selective labeling and enrichment of 5fC-containing DNA fragments, followed by deamination mediated by apolipoprotein B mRNA-editing catalytic polypeptide-like 3A (APOBEC3A or A3A) and sequencing. In the CLED-seq process, while all C, 5mC, and 5hmC are interpreted as T during sequencing, 5fC is still read as C, enabling the precise detection of 5fC in DNA. Using the proposed CLED-seq method, we accomplished genome-wide mapping of 5fC in mouse embryonic stem cells. The mapping study revealed that promoter regions enriched with 5fC overlapped with H3K4me1, H3K4me3, and H3K27ac marks. These findings suggest a correlation between 5fC marks and active gene expression in mESCs. In conclusion, CLED-seq is a straightforward, bisulfite-free method that offers a valuable tool for detecting 5fC in genomes at a single-base resolution.


Assuntos
Citidina Desaminase , Citosina , Citosina/análogos & derivados , Epigênese Genética , Proteínas , Animais , Camundongos , Desaminação , Citosina/metabolismo , 5-Metilcitosina/metabolismo , Mapeamento Cromossômico , DNA/genética , DNA/metabolismo , Metilação de DNA , Mamíferos/metabolismo
5.
Small ; : e2402808, 2024 May 19.
Artigo em Inglês | MEDLINE | ID: mdl-38764281

RESUMO

The metal indium sulfides have attracted extensive research interest in photocatalysis due to regulable atomic configuration and excellent optoelectronic properties. However, the synthesis of metal indium sulfide atomic layers is still challenging since intrinsic non-van-der-Waals layered structures of some components. Here, a surfactant self-assembly growth mechanism is proposed to controllably synthesize metal indium sulfide atomic layers. Eleven types of atomic layers with tunable compositions, thickness, and defect concentrations are successfully achieved namely In2S3, MgIn2S4, CaIn2S4, MnIn2S4, FeIn2S4, ZnIn2S4, Zn2In2S5, Zn4In16S33, CuInS2, CuIn5S8, and CdIn2S4. The typical CaIn2S4 shows a defect-dependence activity for CO2 photoreduction. The designed S vacancies in CaIn2S4 can serve as catalytic centers to activate CO2 molecules via localized electrons for π-back-donation. The engineered S vacancies tune the non-covalent interaction with CO2 and intermediates, manages to tune the free energy, and lower the reaction energy barrier. As a result, the defect-rich CaIn2S4 displays 2.82× improved reduction rate than defect-poor CaIn2S4. Meantime, other components also display promising photocatalytic performance, such as Zn2In2S5 with a H2O2 photosynthesis rate of 292 µmol g-1 h-1 and CuInS2 with N2-NH4 + conversion rate of 54 µmol g-1 h-1. This work paves the way for the multidisciplinary exploration of metal indium sulfide atomic layers with unique photocatalysis properties.

6.
Opt Lett ; 49(2): 274-277, 2024 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-38194546

RESUMO

X ray ghost imaging (XGI) offers both radiation dose-reduction potential and cost-effective benefits owing to the utilization of a single-pixel detector. Most XGI schemes with laboratory x ray sources require a mechanically moving mask for either structured illumination or structured detection. In either configuration, however, its resolution remains limited by the source size and the unit size of the mask. Upon propagation, the details of the object can actually be magnified by the divergence of x rays, but at the same time, the penumbra effect produced by the finite source size is dramatically intensified, which ultimately leads to a degradation of image quality in XGI. To address these limitations, this work proposes a magnified XGI scheme using structured detection equipped with tapered polycapillary optics, which can efficiently suppress the object's penumbra as well as resolve the magnified details of the object. In general, the resolution of this scheme is no longer affected by the source size but by the microcapillary size of polycapillary. Our work fundamentally achieves cancellation of penumbra effect-induced aberration, thus paving the way for high-resolution magnified XGI.

7.
Phys Rev Lett ; 132(3): 035102, 2024 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-38307060

RESUMO

We report the first experimental observation on the reduction of backward scatterings by an instantaneous broadband laser with 0.6% bandwidth in conditions of interest for inertial confinement fusion at the low-coherence Kunwu laser facility. The backscatter of stimulated Brillouin scattering (SBS) was robustly reduced by half at intensities of 1-5×10^{14} W/cm^{2} with the 0.53-µm broadband laser in comparison with the monochromatic laser. As SBS dominates energy loss of laser-plasma interactions, the reduction of that demonstrates the enhancement of laser-target coupling by the use of broadband laser. The mitigation of filamentation leads to the reduction of stimulated Raman backscattering at low intensities. In addition, the three-halves harmonic emission was reduced with the broadband laser as well.

8.
Phys Rev Lett ; 132(6): 066602, 2024 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-38394559

RESUMO

It is commonly believed that topologically nontrivial one-dimensional systems support edge states rather than bulk states at zero energy. In this work, we find an unanticipated case of topological Anderson insulator (TAI) phase where two bulk modes are degenerate at zero energy, in addition to degenerate edge modes. We term this "ungapped TAI" to distinguish it from the previously known gapped TAIs. Our experimental realization of both gapped and ungapped TAIs relies on coupled photonic resonators, in which the disorder in coupling is judiciously engineered by adjusting the spacing between the resonators. By measuring the local density of states both in the bulk and at the edges, we demonstrate the existence of these two types of TAIs, together forming a TAI plateau in the phase diagram. Our experimental findings are well supported by theoretical analysis. In the ungapped TAI phase, we observe stable coexistence of topological edge states and localized bulk states at zero energy, highlighting the distinction between TAIs and traditional topological insulators.

9.
Neuroradiology ; 66(3): 399-407, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38183425

RESUMO

PURPOSE: The optimal primary recanalization strategy for intracranial atherosclerosis-related emergent large vessel occlusion (ICAS-ELVO) remains controversial. We aimed to explore the safety and efficacy of balloon angioplasty as the first-choice recanalization strategy for ICAS-ELVO with small clot burden. METHODS: Consecutive ICAS-ELVO patients presenting with microcatheter "first-pass effect" during endovascular treatment (EVT) were retrospectively analyzed. Patients were divided into preferred balloon angioplasty (PBA) and preferred mechanical thrombectomy (PMT) groups based on the first-choice recanalization strategy. The reperfusion and clinical outcomes between the two groups were compared. RESULTS: Seventy-six patients with ICAS-ELVO involving the microcatheter "first-pass effect" during EVT were enrolled. Compared with patients in the PMT group, those in the PBA group were associated with (i) a higher rate of first-pass recanalization (54.0% vs. 28.9%, p = .010) and complete reperfusion (expanded thrombolysis in cerebral ischemia ≥ 2c; 76.0% vs. 53.8%, p = .049), (ii) shorter puncture-to-recanalization time (49.5 min vs. 89.0 min, p < .001), (iii) lower operation costs (¥48,499.5 vs. ¥ 99,086.0, p < .001), and (iv) better 90-day functional outcomes (modified Rankin scale:0-1; 44.0% vs. 19.2%, p = .032). Logistic regression analysis revealed that balloon angioplasty as the first-choice recanalization strategy was an independent predictor of 90-day excellent functional outcomes for ICAS-ELVO patients with microcatheter "first-pass effect" (adjusted odds ratio = 6.01, 95% confidence interval: 1.15-31.51, p = .034). CONCLUSION: Direct balloon angioplasty potentially improves 90-day functional outcomes for ICAS-ELVO patients with small clot burden, and may be a more appropriate first-choice recanalization strategy than mechanical thrombectomy for these patients.


Assuntos
Angioplastia com Balão , Arteriosclerose Intracraniana , Acidente Vascular Cerebral , Humanos , Acidente Vascular Cerebral/cirurgia , Estudos Retrospectivos , Trombectomia , Arteriosclerose Intracraniana/diagnóstico por imagem , Arteriosclerose Intracraniana/terapia , Arteriosclerose Intracraniana/complicações , Resultado do Tratamento
10.
Mol Cell ; 64(5): 913-925, 2016 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-27840027

RESUMO

TET family enzymes successively oxidize 5-methylcytosine to 5-hydroxymethylcytosine, 5-formylcytosine, and 5-carboxylcytosine, leading to eventual demethylation. 5hmC and TET enzymes occupy distinct chromatin regions, suggesting unknown mechanisms controlling the fate of 5hmC within diverse chromatin environments. Here, we report that SALL4A preferentially associates with 5hmC in vitro and occupies enhancers in mouse embryonic stem cells in a largely TET1-dependent manner. Although most 5hmC at SALL4A peaks undergoes further oxidation, this process is abrogated upon deletion of Sall4 gene, with a concomitant reduction of TET2 at these regions. Thus, SALL4A facilitates further oxidation of 5hmC at its binding sites, which requires its 5hmC-binding activity and TET2, supporting a collaborative action between SALL4A and TET proteins in regulating stepwise oxidation of 5mC at enhancers. Our study identifies SALL4A as a 5hmC binder, which facilitates 5hmC oxidation by stabilizing TET2 association, thereby fine-tuning expression profiles of developmental genes in mouse embryonic stem cells.


Assuntos
5-Metilcitosina/metabolismo , Proteínas de Ligação a DNA/metabolismo , Células-Tronco Embrionárias/metabolismo , Fatores de Transcrição/metabolismo , Animais , Metilação de DNA , Dioxigenases , Elementos Facilitadores Genéticos/fisiologia , Camundongos , Oxirredução , Proteínas Proto-Oncogênicas/metabolismo , Transcrição Gênica
11.
Sensors (Basel) ; 24(7)2024 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-38610244

RESUMO

Acoustic imaging technology has the advantages of non-contact and intuitive positioning. It is suitable for the rapid positioning of defects such as the mechanical loosening, discharge, and DC bias of power equipment. However, the existing research lacks the optimization design of microphone array topology. The acoustic frequency domain characteristics of typical power equipment are elaborately sorted out. After that, the cut-off frequencies of acoustic imaging instruments are determined, to meet the needs of the full bandwidth test requirements. Through a simulation calculation, the circular array is demonstrated to be the optimal shape. And the design parameters affect the imaging performance of the array to varying degrees, indicating that it is difficult to obtain the optimal array topology by an exhaustive method. Aimed at the complex working conditions of power equipment, a topology optimization design method of an acoustic imaging array for power equipment is proposed, and the global optimal solution of microphone array topology is obtained. Compared with the original array, the imaging performance of the improved LF and HF array is promoted by 54% and 49%, respectively. Combined with the simulation analysis and laboratory test, it is verified that the improved array can not only accurately locate the single sound source but also accurately identify the main sound source from the interference of the contiguous sound source.

12.
Sensors (Basel) ; 24(8)2024 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-38676135

RESUMO

To address the inaccuracy of the Constant Acceleration/Constant Velocity (CA/CV) model as the state equation in describing the relative motion state in UAV relative navigation, an adaptive UAV relative navigation method is proposed, which is based on the UAV attitude information provided by Attitude and Heading Reference System (AHRS). The proposed method utilizes the AHRS output attitude parameters as the benchmark for dead reckoning and derives a relative navigation state equation with attitude error as process noise. By integrating the extended Kalman filter output for relative state estimation and employing an adaptive decision rule designed using the innovation of the filter update phase, the proposed method recalculates motion states deviating from the actual motion using the Tasmanian Devil Optimization (TDO) algorithm. The simulation results show that, compared with the CA/CV model, the proposed method reduces the relative position errors by 12%, 23%, and 32% in the X, Y, and Z directions, respectively, and that it reduces the relative velocity errors by 350%, 330%, and 300%, respectively. There is a significant improvement in the relative navigation accuracy.

13.
Molecules ; 29(6)2024 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-38542890

RESUMO

An unparalleled copper(I)-catalyzed synthesis of 1,3,4-oxadiazoles from tertiary amines in one step has been described. The one-pot reactions involving (N-isocyanimine)triphenylphosphorane, tertiary amines, and carboxylic acids resulted in the formation of 1,3,4-oxadiazoles in moderate to good yields through a consecutive oxidative Ugi/aza-Wittig reaction, enabling the direct functionalization of sp3 C-H bonds adjacent to the nitrogen atom. This method offered several notable advantages, including ligands-free, exceptional productivity and a high functional group tolerance. The preliminary biological evaluation demonstrated that compound 4f inhibited hepatoma cells efficiently, suggesting potentially broad applications of the approach for synthesis and medicinal chemistry.


Assuntos
Cobre , Compostos Organofosforados , Oxidiazóis , Cobre/química , Oxidiazóis/química , Aminas/química , Catálise , Estresse Oxidativo
14.
Anal Chem ; 95(28): 10588-10594, 2023 07 18.
Artigo em Inglês | MEDLINE | ID: mdl-37402148

RESUMO

N6-Methyladenosine (m6A) is one of the most abundant and prevalent natural modifications occurring in diverse RNA species. m6A plays a wide range of roles in physiological and pathological processes. Revealing the functions of m6A relies on the faithful detection of individual m6A sites in RNA. However, developing a simple method for the single-base resolution detection of m6A is still a challenging task. Herein, we report an adenosine deamination sequencing (AD-seq) technique for the facile detection of m6A in RNA at single-base resolution. The AD-seq approach capitalizes on the selective deamination of adenosine, but not m6A, by the evolved tRNA adenosine deaminase (TadA) variant of TadA8e or the dimer protein of TadA-TadA8e. In AD-seq, adenosine is deaminated by TadA8e or TadA-TadA8e to form inosine, which pairs with cytidine and is read as guanosine in sequencing. m6A resists deamination due to the interference of the methyl group at the N6 position of adenosine. Thus, the m6A base pairs with thymine and is still read as adenosine in sequencing. The differential readouts from A and m6A in sequencing can achieve the single-base resolution detection of m6A in RNA. Application of the proposed AD-seq successfully identified individual m6A sites in Escherichia coli 23S rRNA. Taken together, the proposed AD-seq allows simple and cost-effective detection of m6A at single-base resolution in RNA, which provides a valuable tool to decipher the functions of m6A in RNA.


Assuntos
RNA de Transferência , RNA , RNA/metabolismo , Desaminação , RNA de Transferência/metabolismo , Adenosina/metabolismo , Adenosina Desaminase/metabolismo
15.
Anal Chem ; 95(2): 1556-1565, 2023 01 17.
Artigo em Inglês | MEDLINE | ID: mdl-36563112

RESUMO

DNA methylation (5-methylcytosine, 5mC) is the most important epigenetic modification in mammals. Deciphering the roles of 5mC relies on the quantitative detection of 5mC at the single-base resolution. Bisulfite sequencing (BS-seq) is the most often employed technique for mapping 5mC in DNA. However, bisulfite treatment may cause serious degradation of input DNA due to the harsh reaction conditions. Here, we engineered the human apolipoprotein B mRNA-editing catalytic polypeptide-like 3C (A3C) protein to endow the engineered A3C (eA3C) protein with differential deamination activity toward cytosine and 5mC. By the virtue of the unique property of eA3C, we proposed an engineered A3C sequencing (EAC-seq) method for the bisulfite-free and quantitative mapping of 5mC in DNA at the single-base resolution. In EAC-seq, the eA3C protein can deaminate C but not 5mC, which is employed to differentiate C and 5mC in sequencing. Using the EAC-seq method, we quantitatively detected 5mC in genomic DNA of lung cancer tissue. In contrast to the harsh reaction conditions of BS-seq, which could lead to significant degradation of DNA, the whole procedure of EAC-seq is carried out under mild conditions, thereby preventing DNA damage. Taken together, the EAC-seq approach is bisulfite-free and straightforward, making it an invaluable tool for the quantitative detection of 5mC in limited DNA at the single-base resolution.


Assuntos
5-Metilcitosina , Citidina Desaminase , Metilação de DNA , Humanos , 5-Metilcitosina/metabolismo , Citidina Desaminase/genética , Citidina Desaminase/metabolismo , Citosina , DNA/genética , DNA/metabolismo , Epigênese Genética , Análise de Sequência de DNA/métodos , Sulfitos/metabolismo
16.
Opt Lett ; 48(7): 1618-1621, 2023 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-37221724

RESUMO

Since the paradigm shift in 2009 from pseudo-thermal ghost imaging (GI) to computational GI using a spatial light modulator, computational GI has enabled image formation via a single-pixel detector and thus has a cost-effective advantage in some unconventional wave bands. In this Letter, we propose an analogical paradigm known as computational holographic ghost diffraction (CH-GD) to shift ghost diffraction (GD) from classical to computational by using self-interferometer-assisted measurement of field correlation functions rather than intensity correlation functions. More than simply "seeing" the diffraction pattern of an unknown complex volume object with single-point detectors, CH-GD can retrieve the diffracted light field's complex amplitude and can thus digitally refocus to any depth in the optical link. Moreover, CH-GD has the potential to obtain the multimodal information including intensity, phase, depth, polarization, and/or color in a more compact and lensless manner.

17.
Phys Rev Lett ; 131(17): 176401, 2023 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-37955469

RESUMO

The disorder systems host three types of fundamental quantum states, known as the extended, localized, and critical states, of which the critical states remain being much less explored. Here we propose a class of exactly solvable models which host a novel type of exact mobility edges (MEs) separating localized states from robust critical states, and propose experimental realization. Here the robustness refers to the stability against both single-particle perturbation and interactions in the few-body regime. The exactly solvable one-dimensional models are featured by a quasiperiodic mosaic type of both hopping terms and on-site potentials. The analytic results enable us to unambiguously obtain the critical states which otherwise require arduous numerical verification including the careful finite size scalings. The critical states and new MEs are shown to be robust, illustrating a generic mechanism unveiled here that the critical states are protected by zeros of quasiperiodic hopping terms in the thermodynamic limit. Further, we propose a novel experimental scheme to realize the exactly solvable model and the new MEs in an incommensurate Rydberg Raman superarray. This Letter may pave a way to precisely explore the critical states and new ME physics with experimental feasibility.

18.
Phys Rev Lett ; 130(4): 043201, 2023 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-36763419

RESUMO

The Floquet engineering opens the way to create new topological states without counterparts in static systems. Here, we report the experimental realization and characterization of new anomalous topological states with high-precision Floquet engineering for ultracold atoms trapped in a shaking optical Raman lattice. The Floquet band topology is manipulated by tuning the driving-induced band crossings referred to as band inversion surfaces (BISs), whose configurations fully characterize the topology of the underlying states. We uncover various exotic anomalous topological states by measuring the configurations of BISs that correspond to the bulk Floquet topology. In particular, we identify an unprecedented anomalous Floquet valley-Hall state that possesses anomalous helical-like edge modes protected by valleys and a chiral state with high Chern number.

19.
Phys Rev Lett ; 131(13): 133601, 2023 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-37831993

RESUMO

Berry curvature is a fundamental element to characterize topological quantum physics, while a full measurement of Berry curvature in momentum space was not reported for topological states. Here we achieve two-dimensional Berry curvature reconstruction in a photonic quantum anomalous Hall system via Hall transport measurement of a momentum-resolved wave packet. Integrating measured Berry curvature over the two-dimensional Brillouin zone, we obtain Chern numbers corresponding to -1 and 0. Further, we identify bulk-boundary correspondence by measuring topology-linked chiral edge states at the boundary. The full topological characterization of photonic Chern bands from Berry curvature, Chern number, and edge transport measurements enables our photonic system to serve as a versatile platform for further in-depth study of novel topological physics.

20.
J Org Chem ; 88(18): 13125-13134, 2023 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-37616489

RESUMO

A new one-pot synthesis of imidazo[1,2-a]pyridine-fused 1,3-benzodiazepine derivatives via a sequential GBB-3CR/Pd(II)-catalyzed azide-isocyanide coupling/cyclization process was developed. The Groebke-Blackburn-Bienaymé three-component reactions (GBB-3CR) of 2-aminopyridine, 2-azidobenzaldehydes, and isocyanides in the presence of a catalytic amount of p-toluenesulfonic acid gave azide intermediates without separation. The reaction was followed by using another molecule of isocyanides to produce imidazo[1,2-a]pyridine-fused 1,3-benzodiazepine derivatives in good yields by the Pd(II)-catalyzed azide-isocyanide coupling/cyclization reaction. The synthetic approach produces novel nitrogen-fused polycyclic heterocycles under mild reaction conditions. The preliminary biological evaluation demonstrated that compound 6a inhibited glioma cells efficiently, suggesting potentially broad applications of the approach for synthesis and medicinal chemistry.

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