Electron–electron interactions play an important role in graphene and related systems and can induce exotic quantum states, especially in a stacked bilayer with a small twist angle1–7. For bilayer ...graphene where the two layers are twisted by the ‘magic angle’, flat band and strong many-body effects lead to correlated insulating states and superconductivity4–7. In contrast to monolayer graphene, the band structure of untwisted bilayer graphene can be further tuned by a displacement field8–10, providing an extra degree of freedom to control the flat band that should appear when two bilayers are stacked on top of each other. Here, we report the discovery and characterization of displacement field-tunable electronic phases in twisted double bilayer graphene. We observe insulating states at a half-filled conduction band in an intermediate range of displacement fields. Furthermore, the resistance gap in the correlated insulator increases with respect to the in-plane magnetic fields and we find that the g factor, according to the spin Zeeman effect, is ~2, indicating spin polarization at half-filling. These results establish twisted double bilayer graphene as an easily tunable platform for exploring quantum many-body states.Placing two Bernal-stacked graphene bilayers on top of each other with a small twist angle gives correlated states. As the band structure can be tuned by an electric field, this platform is a more varied setting to study correlated electrons.
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FZAB, GEOZS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Halide perovskite quantum dots (QDs), primarily regarded as optoelectronic materials for LED and photovoltaic devices, have not been applied for photochemical conversion (e.g., water splitting or CO2 ...reduction) applications because of their insufficient stability in the presence of moisture or polar solvents. Herein, we report the use of CsPbBr3 QDs as novel photocatalysts to convert CO2 into solar fuels in nonaqueous media. Under AM 1.5G simulated illumination, the CsPbBr3 QDs steadily generated and injected electrons into CO2, catalyzing CO2 reduction at a rate of 23.7 μmol/g h with a selectivity over 99.3%. Additionally, through the construction of a CsPbBr3 QD/graphene oxide (CsPbBr3 QD/GO) composite, the rate of electron consumption increased 25.5% because of improved electron extraction and transport. This study is anticipated to provide new opportunities to utilize halide perovskite QD materials in photocatalytic applications.
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IJS, KILJ, NUK, PNG, UL, UM
Since December 2019, an epidemic caused by novel coronavirus (2019-nCoV) infection has occurred unexpectedly in China. As of 8 pm, 31 January 2020, more than 20 pediatric cases have been reported in ...China. Of these cases, ten patients were identified in Zhejiang Province, with an age of onset ranging from 112 days to 17 years. Following the latest
National recommendations for diagnosis and treatment of pneumonia caused by 2019-nCoV
(the 4th edition) and current status of clinical practice in Zhejiang Province, recommendations for the diagnosis and treatment of respiratory infection caused by 2019-nCoV for children were drafted by the National Clinical Research Center for Child Health, the National Children’s Regional Medical Center, Children’s Hospital, Zhejiang University School of Medicine to further standardize the protocol for diagnosis and treatment of respiratory infection in children caused by 2019-nCoV.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Recent efforts have promoted programmable wireless environments (PWEs) to enhance the reception quality in high-frequency bands via reconfigurable intelligent surfaces (RISs). However, relevant ...research efforts are limited to setups with stationary users. This paper shows that crowd mobility in indoor PWEs induces spatio-temporal shadows on the surfaces, resulting in spatio-temporal sparsity in channel gains due to signal blockages. This overlooked aspect impacts the operation strategy of PWEs as the shadowed RIS tiles would contribute to the overheads while offering almost no improvement to the reception quality. Hence, this paper proposes an optimal strategy that excludes the shadowed tiles, which maximizes the utilization efficiency of RISs while minimizing the overheads. Since signal blockage is tied with the details of user mobility, a general model does not exist to identify such shadowed tiles for exclusion. Hence, we follow a data-driven approach that capitalizes on a realistic indoor mobility model and ray-tracing to generate the channel data. However, conventional ray-tracing presents high complexity that hinders data generation. So, we propose an approach to identify the shadow regions with a nine-order of magnitude reduction in complexity to efficiently generate the channel data. Furthermore, we present two exclusion strategies that offer guaranteed and best-effort quality-of-service support, and each can identify the tiles to be excluded via a search method with a complexity of <inline-formula> <tex-math notation="LaTeX">\mathcal {O}(N) </tex-math></inline-formula> for <inline-formula> <tex-math notation="LaTeX">N </tex-math></inline-formula> tiles. The results indicate that the proposed strategies reduce the overheads by <inline-formula> <tex-math notation="LaTeX">45-50\% </tex-math></inline-formula> while maintaining optimal service quality in various environments, operation frequencies, and user and access point density.
The palladium‐catalyzed asymmetric 4+3 cyclization of trimethylenemethane donors with benzofuran‐derived azadienes furnishes chiral benzofuro3,2‐bazepine frameworks in high yields (up to 98 %) with ...exclusive regioselectivities and excellent stereoselectivities (up to >20:1 d.r., >99 % ee). This catalytic asymmetric 4+3 cyclization of Pd‐trimethylenemethane can enrich the arsenal of Pd‐TMM reactions in organic synthesis. In addition, this strategy provides an alternative approach to chiral azepines by a transition‐metal‐catalyzed asymmetric 4+3 cyclization.
A wide range of chiral benzofuro3,2‐bazepine skeletons can be synthesized in excellent yields, high diastereoselectivities, and excellent enantioselectivities through the title reaction. The diastereoselectivity of the reaction can be controlled through ligand R1, with a cyano group affording trans products and a diphenyl ketimine group affording cis products.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
NiFe-based (oxy)hydroxides are the benchmark catalysts for the oxygen evolution reaction (OER) in alkaline medium, however, it is still challenging to control their structures and compositions. ...Herein, molybdates (NiFe(MoO
)
) are applied as unique precursors to synthesize ultrafine Mo modified NiFeO
H
(oxy)hydroxide nanosheet arrays. The electrochemical activation process enables the molybdate ions (MoO
) in the precursors gradually dissolve, and at the same time, hydroxide ions (OH
) in the electrolyte diffuse into the precursor and react with Ni
and Fe
ions in confined space to produce ultrafine NiFeO
H
(oxy)hydroxides nanosheets (<10 nm), which are densely arranged into microporous arrays and maintain the rod-like morphology of the precursor. Such dense ultrafine nanosheet arrays produce rich edge planes on the surface of NiFeO
H
(oxy)hydroxides to expose more active sites. More importantly, the capillary phenomenon of microporous structures and hydrophilic hydroxyl groups induce the superhydrophilicity and the rough surface produces the superaerophobic characteristic for bubbles. With these advantages, the optimized catalyst exhibits excellent performance for OER, with a small overpotential of 182 mV at 10 mA cm
and long-term stability (200 h) at 200 mA cm
. Theoretical calculations show that the modification of Mo enhances the electron delocalization and optimizes the adsorption of intermediates.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Information security has gained increasing attention in the past decade, leading to the development of advanced materials for anti‐counterfeiting, encryption and instantaneous information display. ...However, it remains challenging to achieve high information security with simple encryption procedures and low‐energy stimuli. Herein, a series of strain/temperature‐responsive liquid crystal elastomers (LCEs) are developed to achieve dual‐modal, multi‐level information encryption and real‐time, rewritable transient information display. The as‐prepared polydomain LCEs can change from an opaque state to a transparent state under strain or temperature stimuli, with the transition strains or temperatures highly dependent on the concentration of long‐chain flexible spacers. Information encrypted by different LCE inks can be decrypted under specific strains or temperatures, leading to multi‐level protection of information security. Furthermore, with the combination of the phase transition of polydomain LCEs and the photothermal effect of multi‐walled carbon nanotubes (MWCNTs), we achieved a repeatable transient information display by using near‐infrared (NIR) light as a pen for writing. This study provides new insight into the development of advanced encryption materials with versatility and high security for broad applications.
A series of dual‐responsive polydomain liquid crystal elastomers (LCEs) are developed, which can change from opaque to transparent states under strain or temperature stimuli. The as‐prepared LCEs can achieve multi‐level information encryption based on strain response and real‐time, rewritable transient information display upon incorporating photothermal multi‐walled carbon nanotubes.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
•High-frequency repetitive transcranial stimulation can improve part of cognitive function in patients with bipolar disorder during remission.•Repetitive transcranial magnetic stimulation is a safe ...method for interpreting cognitive function in patients with bipolar disorder during remission.•The MATRICS Consensus Cognitive Battery (MCCB) can be used to assess cognitive function in patients with bipolar disorder.
Patients with bipolar disorder (BD) present widespread and significant neurocognitive impairments during all stages of the disorder. Repetitive transcranial magnetic stimulation (rTMS) has been used to improve clinical outcomes in common psychiatric diseases, such as depression, anxiety disorders, schizophrenia, and BD. Whether rTMS can improve cognitive function in BD patients remains unclear. The present study explored the regulatory effects of rTMS on cognitive function in patients with BD.
Fifty-two eligible subjects with BD were randomly assigned to receive active or sham rTMS via high-speed magnetic stimulator with a figure-of-eight coil for 10 consecutive days. In the active rTMS group, a total of 25,000 stimuli were applied over the left dorsolateral prefrontal cortex at 110% of the motor threshold. The sham group received corresponding sham stimulation. Clinical manifestations and cognitive functions were assessed using a modified 24-item Hamilton Depression Rating Scale (HDRS), the Young Mania Rating Scale (YMRS), and the MATRICS Consensus Cognitive Battery (MCCB).
Ten consecutive days of high-frequency active rTMS improved scores on the Wechsler Memory Scale-III Spatial Span, and the MCCB Category Fluency subtest, without intolerable adverse effects. No significant differences in HDRS or YMRS scores were found between groups.
No follow-up after the intervention. The effect of the drug on cognitive function in subjects was not excluded.
Short-term rTMS can improve cognitive function in BD patients.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract
The changes of broad emission lines should be a crucial issue in understanding the physical properties of changing-look active galactic nuclei (CL-AGNs). Here we present the results of an ...intensive and homogeneous 6 month long reverberation mapping (RM) monitoring campaign during a low-activity state of the CL-AGN Seyfert galaxy NGC 3516. Photometric and spectroscopic monitoring was carried out during 2018–2019 with the Lijiang 2.4 m telescope. The sampling is 2 days in most nights, and the average sampling is ∼3 days. The rest-frame time lags of H
α
and H
β
are
and
days, respectively. From an rms H
β
line dispersion of
σ
line
= 1713.3 ± 46.7 km s
−1
and a virial factor of
f
σ
= 5.5, the central black hole mass of NGC 3516 is estimated to be
, which is in agreement with previous estimates. The velocity-resolved delays show that the time lags increase toward negative velocity for both H
α
and H
β
. The velocity-resolved RM of H
α
is done for the first time. These RM results are consistent with other observations before the spectral-type change, indicating a basically constant broad-line region structure during the CL process. The CL model of changes of accretion rate seems to be favored by long-term H
β
variability and RM observations of NGC 3516.
Liver sinusoidal endothelial cells (LSECs) critically regulate liver homeostasis and diseases through angiocrine factors. Notch is critical in endothelial cells (ECs). In the current study, Notch ...signaling was activated by inducible EC‐specific expression of the Notch intracellular domain (NIC). We found that endothelial Notch activation damaged liver homeostasis. Notch activation resulted in decreased fenestration and increased basement membrane, and a gene expression profile with decreased LSEC‐associated genes and increased continuous EC‐associated genes, suggesting LSEC dedifferentiation. Consistently, endothelial Notch activation enhanced hepatic fibrosis (HF) induced by CCl4. Notch activation attenuated endothelial nitric oxide synthase (eNOS)/soluble guanylate cyclase (sGC) signaling, and activation of sGC by 3‐(5′‐hydroxymethyl‐2′‐furyl)‐1‐benzylindazole (YC‐1) reversed the dedifferentiation phenotype. In addition, Notch activation subverted the hepatocyte‐supporting angiocrine profile of LSECs by down‐regulating critical hepatocyte mitogens, including Wnt2a, Wnt9b, and hepatocyte growth factor (HGF). This led to compromised hepatocyte proliferation under both quiescent and regenerating conditions. Whereas expression of Wnt2a and Wnt9b was dependent on eNOS‐sGC signaling, HGF expression was not rescued by the sGC activator, suggesting heterogeneous mechanisms of LSECs to maintain hepatocyte homeostasis. Conclusion: Endothelial Notch activation results in LSEC dedifferentiation and accelerated liver fibrogenesis through eNOS‐sGC signaling, and alters the angiocrine profile of LSECs to compromise hepatocyte proliferation and liver regeneration (LR). (Hepatology 2018).
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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