Optical control of structural and electronic properties of Weyl semimetals allows development of switchable and dissipationless topological devices at the ultrafast scale. An unexpected ...orbital-selective photoexcitation in type-II Weyl material WTe2 is reported under linearly polarized light (LPL), inducing striking transitions among several topologically-distinct phases mediated by effective electron-phonon couplings. The symmetry features of atomic orbitals comprising the Weyl bands result in asymmetric electronic transitions near the Weyl points, and in turn a switchable interlayer shear motion with respect to linear light polarization, when a near-infrared laser pulse is applied. Consequently, not only annihilation of Weyl quasiparticle pairs, but also increasing separation of Weyl points can be achieved, complementing existing experimental observations. In this work, we provide a new perspective on manipulating the Weyl node singularity and coherent control of electron and lattice quantum dynamics simultaneously.Photoexcitation in Weyl semimetals is recently reported to induce topological phase transitions useful for ultrafast switching devices. Here, the authors predict that the symmetry of the atomic orbitals comprising the Weyl bands in response to linear light polarization allows for not only annihilation but also separation of Weyl quasiparticles.
Abstract
The origin of charge density waves (CDWs) in TiSe
$_{2}$$
2
has long been debated, mainly due to the difficulties in identifying the timescales of the excitonic pairing and electron–phonon ...coupling (EPC). Without a time-resolved and microscopic mechanism, one has to assume simultaneous appearance of CDW and periodic lattice distortions (PLD). Here, we accomplish a complete separation of ultrafast exciton and PLD dynamics and unravel their interplay in our real-time time-dependent density functional theory simulations. We find that laser pulses knock off the exciton order and induce a homogeneous bonding–antibonding transition in the initial 20 fs, then the weakened electronic order triggers ionic movements antiparallel to the original PLD. The EPC comes into play after the initial 20 fs, and the two processes mutually amplify each other leading to a complete inversion of CDW ordering. The self-amplified dynamics reproduces the evolution of band structures in agreement with photoemission experiments. Hence we resolve the key processes in the initial dynamics of CDWs that help elucidate the underlying mechanism.
Abstract
Light-modulated electron-phonon coupling (EPC) is significant in many intriguing phenomena including light-enhanced superconductivity, polaron formation, and hidden charge orders, which ...provides a powerful strategy to engineer materials’ functionalities on demand. Here we explore EPC in photoexcited graphene during the ultrafast photocarrier dynamics with a phonon bath. Via analysing energy transport between electrons and phonons, light-induced EPC enhancement by more than one order of magnitude is demonstrated, which originates from the dynamic distribution of photoexcited carriers out of equilibrium. Excellent agreements between theory and experiment have been achieved, justifying the validity of the present approach for extracting excited-state dynamic properties. Our result unravels a crucial impact of photoexcitation on EPC by modulating the density and distribution of photocarriers, and provides a useful strategy for tracking ultrafast EPC in real time.
Methods to probe and understand the dynamic response of materials following impulsive excitation are important for many fields, from materials and energy sciences to chemical and neuroscience. To ...design more efficient nano, energy, and quantum devices, new methods are needed to uncover the dominant excitations and reaction pathways. In this work, we implement a newly-developed superlet transform-a super-resolution time-frequency analytical method-to analyze and extract phonon dynamics in a laser-excited two-dimensional (2D) quantum material. This quasi-2D system, 1T-TaSe
, supports both equilibrium and metastable light-induced charge density wave (CDW) phases mediated by strongly coupled phonons. We compare the effectiveness of the superlet transform to standard time-frequency techniques. We find that the superlet transform is superior in both time and frequency resolution, and use it to observe and validate novel physics. In particular, we show fluence-dependent changes in the coupled dynamics of three phonon modes that are similar in frequency, including the CDW amplitude mode, that clearly demonstrate a change in the dominant charge-phonon couplings. More interestingly, the frequencies of the three phonon modes, including the strongly-coupled CDW amplitude mode, remain time- and fluence-independent, which is unusual compared to previously investigated materials. Our study opens a new avenue for capturing the coherent evolution and couplings of strongly-coupled materials and quantum systems.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
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LCZ696, an angiotensin receptor–neprilysin inhibitor (ARNi), is reported to play a cardioprotective role after acute myocardial infarction (AMI). Angiotensin-converting enzyme ...inhibitors(ACEIs) have similar roles. However, it is unclear whether the combination of the two drugs has a better protective effect. The purpose of this study was to investigate the effect of this combination therapy after AMI.
Male C57BL/6 J mice subjected to ligation of left anterior descending artery were treated for 4 weeks with LCZ696, ACEI(benazepril), or both(combination therapy) after induction of MI. Cardiac function, hemodynamics, and inflammatory factors were evaluated at 1 st day, 14th day, and 28th day. Heart weight and myocardial fibrosis were measured at the end of the experiment.
Blood pressure was lower in all treatment groups than in the control group. The combination therapy group had the strongest antihypertensive effect. Compared with LCZ696 or benazepril, treatment with combination therapy increased ejection fraction, fractional shortening, and cardiac output and decreased N-terminal pro-B-type natriuretic peptide(NT-proBNP). The ratios of heart weight to body weight in all treatment groups were less than that in the control group. Compared with the control and LCZ696 group, the fibrotic area in the combination therapy group was suppressed and had a lower level of TGF-β1 in the left ventricle. The plasma concentration of bradykinin and renin in the combination therapy group were highest among groups at 14th and 28th day.
LCZ696 in combination with benazepril showed better positive effects in modulating heart failure and myocardial fibrosis after acute AMI in mice and affect some inflammatory markers.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Plasma EBV DNA level post-IC was an independent predictor for LRFS, RRFS, DMFS, OS, and PFS.•We constructed a post-IC EBV DNA-based RPA risk stratification model in LA-NPC.•The RPA model provides ...improved risk discrimination over the 8th edition of the TNM staging system.
To evaluate the prognostic value of plasma Epstein-Barr virus (EBV) DNA level post-induction chemotherapy (IC) for patients with nasopharyngeal carcinoma (NPC).
A total of 893 newly diagnosed NPC patients treated with IC were retrospectively reviewed. The recursive partitioning analysis (RPA) was performed to construct a risk stratification model. The receiver operating characteristic (ROC) analysis was applied to determine the optimal cut-off value of post-IC EBV DNA.
Post-IC EBV DNA levels and overall stage were independent predictors for distant metastasis-free survival (DMFS), overall survival (OS), and progression-free survival (PFS). The RPA model base on post-IC EBV DNA and overall stage categorized the patients into three distinct risk groups: RPA I (low-risk: stage II-III and post-IC EBV DNA < 200 copies/mL), RPA II (median-risk: stage II-III and post-IC EBV DNA ≥ 200 copies/mL, or stage IVA and post-IC EBV DNA < 200 copies/mL), and RPA III (high-risk: stage IVA and post-IC EBV DNA ≥ 200 copies/mL), with 3-year PFS of 91.1%, 82.6%, and 60.2%, respectively (p < 0.001). The DMFS and OS rates in different RPA groups were also distinct. The RPA model showed better risk discrimination than either the overall stage or post-RT EBV DNA alone.
Plasma EBV DNA level post-IC was a robust prognostic biomarker for NPC. We developed an RPA model that provides improved risk discrimination over the 8th edition of the TNM staging system by integrating the post-IC EBV DNA level and the overall stage.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Objective. The construction of in vitro three-dimensional (3D) neural tissue has to overcome two main types of challenges: (1) How to obtain enough number of functional neurons from stem cells in 3D ...culture; (2) How to wire those lately developed neurons into functional neural networks. Here, we describe the potential of using direct current (DC) electric field (EF) together with basic fibroblast growth factor (bFGF) synergistically in promoting neural stem cell (NSC) neuronal differentiation following by directing neurite outgrowth in the 3D neural tissue construction. Approach. By adjusting the electrical stimulation setup in this study, long-term electrical stimulation could be present in vitro. At an EF strength of 150 mV mm−1, cell responses, including cell viability, neuronal differentiation, cell morphology, the length of neuronal processes, synaptic structure and neural network formation, were quantified and analyzed. Main results. Analysis revealed that NSCs showed no significant cell death after certain EF treatments. EF-stimulated NSCs in 3D Matrigel mainly differentiated into neurons, but unlike NSCs in two-dimensional conditions, their processes were flat and stunted. When combined with bFGF, EF stimulation provided appropriate bioactive cues to establish engineered neural tissue with a proper neuronal cell number, highly branched neurites, and a well-developed neuronal network. Significance. It is for the first time the synergistic effects of EF and bFGF stimulation have been evaluated in inducing the differentiation of NSCs into neurons and the acquisition of long neurites in a culture environment of in vitro 3D model. These optimized conditions may allow a well-developed neuronal network to be established within hydrogel droplets.
Arteriosclerosis obliterans (ASO) is a major cause of adult limb loss worldwide. Autophagy of vascular endothelial cell (VEC) contributes to the ASO progression. However, the molecular mechanism that ...controls VEC autophagy remains unclear. In this study, we aimed to explore the role of the GRB2 associated binding protein 1 (GAB1) in regulating VEC autophagy.
In vivo and in vitro studies were applied to determine the loss of adapt protein GAB1 in association with ASO progression. Histological GAB1 expression was measured in sclerotic vascular intima and normal vascular intima. Gain- and loss-of-function of GAB1 were applied in VEC to determine the effect and potential downstream signaling of GAB1.
The autophagy repressor p62 was significantly downregulated in ASO intima as compared to that in healthy donor (0.80 vs. 0.20, t = 6.43, P < 0.05). The expression level of GAB1 mRNA (1.00 vs. 0.24, t = 7.41, P < 0.05) and protein (0.72 vs. 0.21, t = 5.97, P < 0.05) was significantly decreased in ASO group as compared with the control group. Loss of GAB1 led to a remarkable decrease in LC3II (1.19 vs. 0.68, t = 5.99, P < 0.05), whereas overexpression of GAB1 significantly led to a decrease in LC3II level (0.41 vs. 0.93, t = 7.12, P < 0.05). Phosphorylation levels of JNK and p38 were significantly associated with gain- and loss-of-function of GAB1 protein.
Loss of GAB1 promotes VEC autophagy which is associated with ASO. GAB1 and its downstream signaling might be potential therapeutic targets for ASO treatment.
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