The AB-BA domain wall in gapped graphene bilayers is a rare naked structure hosting topological electronic states. Although it has been extensively studied in theory, a direct imaging of its ...topological edge states is still missing. Here we image the topological edge states at the graphene bilayer domain wall by using scanning tunnelling microscope. The simultaneously obtained atomic-resolution images of the domain wall provide us unprecedented opportunities to measure the spatially varying edge states within it. The one-dimensional conducting channels are observed to be mainly located around the two edges of the domain wall, which is reproduced quite well by our theoretical calculations. Our experiment further demonstrates that the one-dimensional topological states are quite robust even in the presence of high magnetic fields. The result reported here may raise hopes of graphene-based electronics with ultra-low dissipation.
As of June 8, 2020, the global reported number of COVID-19 cases had reached more than 7 million with over 400 000 deaths. The household transmissibility of the causative pathogen, severe acute ...respiratory syndrome coronavirus 2 (SARS-CoV-2), remains unclear. We aimed to estimate the secondary attack rate of SARS-CoV-2 among household and non-household close contacts in Guangzhou, China, using a statistical transmission model.
In this retrospective cohort study, we used a comprehensive contact tracing dataset from the Guangzhou Center for Disease Control and Prevention to estimate the secondary attack rate of COVID-19 (defined as the probability that an infected individual will transmit the disease to a susceptible individual) among household and non-household contacts, using a statistical transmission model. We considered two alternative definitions of household contacts in the analysis: individuals who were either family members or close relatives, such as parents and parents-in-law, regardless of residential address, and individuals living at the same address regardless of relationship. We assessed the demographic determinants of transmissibility and the infectivity of COVID-19 cases during their incubation period.
Between Jan 7, 2020, and Feb 18, 2020, we traced 195 unrelated close contact groups (215 primary cases, 134 secondary or tertiary cases, and 1964 uninfected close contacts). By identifying households from these groups, assuming a mean incubation period of 5 days, a maximum infectious period of 13 days, and no case isolation, the estimated secondary attack rate among household contacts was 12·4% (95% CI 9·8–15·4) when household contacts were defined on the basis of close relatives and 17·1% (13·3–21·8) when household contacts were defined on the basis of residential address. Compared with the oldest age group (≥60 years), the risk of household infection was lower in the youngest age group (<20 years; odds ratio OR 0·23 95% CI 0·11–0·46) and among adults aged 20–59 years (OR 0·64 95% CI 0·43–0·97). Our results suggest greater infectivity during the incubation period than during the symptomatic period, although differences were not statistically significant (OR 0·61 95% CI 0·27–1·38). The estimated local reproductive number (R) based on observed contact frequencies of primary cases was 0·5 (95% CI 0·41–0·62) in Guangzhou. The projected local R, had there been no isolation of cases or quarantine of their contacts, was 0·6 (95% CI 0·49–0·74) when household was defined on the basis of close relatives.
SARS-CoV-2 is more transmissible in households than SARS-CoV and Middle East respiratory syndrome coronavirus. Older individuals (aged ≥60 years) are the most susceptible to household transmission of SARS-CoV-2. In addition to case finding and isolation, timely tracing and quarantine of close contacts should be implemented to prevent onward transmission during the viral incubation period.
US National Institutes of Health, Science and Technology Plan Project of Guangzhou, Project for Key Medicine Discipline Construction of Guangzhou Municipality, Key Research and Development Program of China.
The transcription factor nuclear factor erythroid-derived 2-like 2 (NRF2) participates in the activation of the antioxidant cytoprotective pathway and other important physiological processes to ...maintain cellular homeostasis. The dysregulation of NRF2 activity plays a role in various diseases, such as cardiovascular diseases, neurodegenerative diseases, and cancer. Thus, NRF2 activity is tightly regulated through multiple mechanisms, among which phosphorylation by kinases is critical in the posttranslational regulation of NRF2. For instance, PKC, casein kinase 2, and AMP-activated kinase positively, while GSK-3 negatively regulates NRF2 activity through phosphorylation of different sites. Here, we provide an overview of the phosphorylation regulation pattern of NRF2 and discuss the therapeutic potential of interventions targeting NRF2 phosphorylation.
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•Protein kinases phosphorylate Nrf2 to modulate its stability and/or activity.•Phosphorylation regulation of NRF2 bridges NRF2 activity to a series of biological events.•Targeting NRF2 phosphorylation regulation shows therapeutic potential for multiple inflammation-related diseases.
This paper proposes lossless, reversible, and combined data hiding schemes for ciphertext images encrypted by public-key cryptosystems with probabilistic and homomorphic properties. In the lossless ...scheme, the ciphertext pixels are replaced with new values to embed the additional data into several least significant bit planes of ciphertext pixels by multilayer wet paper coding. Then, the embedded data can be directly extracted from the encrypted domain, and the data-embedding operation does not affect the decryption of original plaintext image. In the reversible scheme, a preprocessing is employed to shrink the image histogram before image encryption, so that the modification on encrypted images for data embedding will not cause any pixel oversaturation in plaintext domain. Although a slight distortion is introduced, the embedded data can be extracted and the original image can be recovered from the directly decrypted image. Due to the compatibility between the lossless and reversible schemes, the data-embedding operations in the two manners can be simultaneously performed in an encrypted image. With the combined technique, a receiver may extract a part of embedded data before decryption, and extract another part of embedded data and recover the original plaintext image after decryption.
Salinity stress from soil or irrigation water can significantly limit the growth and development of plants. Emerging evidence suggests that hydrogen sulfide (H2S), as a versatile signal molecule, can ...ameliorate salt stress-induced adverse effects. However, the possible physiological mechanism underlying H2S-alleviated salt stress in cucumber remains unclear. Here, a pot experiment was conducted with an aim to examine the possible mechanism of H2S in enhancement of cucumber salt stress tolerance. The results showed that H2S ameliorated salt-induced growth inhibition and alleviated the reduction in photosynthetic attributes, chlorophyll fluorescence and stomatal parameters. Meanwhile H2S increased the endogenous H2S level concomitant with increased activities of D/L-cysteine desulfhydrase and β-cyanoalanine synthase and decreased activities of O-acetyl-L-serine(thiol)lyase under excess NaCl. Notably, H2S maintained Na+ and K+ homeostasis via regulation of the expression of PM H+-ATPase, SOS1 and SKOR at the transcriptional level under excess NaCl. Moreover, H2S alleviated salt-induced oxidative stress as indicated by lowered lipid peroxidation and reactive oxygen species accumulation through an enhanced antioxidant system. Altogether, these results demonstrated that application of H2S could protect cucumber seedlings against salinity stress, likely by keeping the Na+/K+ balance, controlling the endogenous H2S level by regulating the H2S synthetic and decomposition enzymes, and preventing oxidative stress by enhancing the antioxidant system under salinity stress.
Mulberry extract has been proven to have the effect of resisting alcohol damage, but its mechanism is still unclear. In this study, the composition of mulberry ethanol extract (MBE) was identified by ...LC-MS/MS and the main components of MBE were ascertained by measuring. Gastric mucosal epithelial (GES-1) cells were used to elucidate the mechanism of MBE and rutin (the central part of MBE) helped protect against alcohol damage. The results revealed that phenolics accounted for the majority of MBE, accounting for 308.6 mg/g gallic acid equivalents and 108 substances were identified, including 37 flavonoids and 50 non-flavonoids. The treatment of 400 μg/mL MBE and 320 μM rutin reduced early cell apoptosis and the content of intracellular reactive oxygen species, malondialdehyde and increased glutathione. The qPCR results indicated that the MBE inhibits the expression of genes in the mitogen-activated protein kinase (MAPK) pathway, including p38, JNK, ERK and caspase-3; rutin inhibits the expression of p38 and caspase-3. Overall, MBE was able to reduce the oxidative stress of GES-1 cells and regulated apoptosis-related genes of the MAPK pathway. This study provides information for developing anti-ethanol injury drugs or functional foods.
This paper reviews the morphological change in the Yangtze River delta due to increasing human impacts from three major aspects. The first is the reduction of sediment supply to the ocean due to dam ...construction, soil conservation, and sand mining within the Yangtze River basin. The reduced sediment supply has decreased the progradation rate of the delta and triggered erosion in the front of the delta. The second impact relates to the reclamation of intertidal wetlands by human activities. Since the 1950s, approximately 1100 km2 of intertidal land has been embanked, resulting in the disappearance of salt marshes and even the entire intertidal zone along some sections of the coastline. The third change in the delta due to human interference is the construction of deep-waterway structures at the mouth bar, which has greatly modified the local hydrodynamics and morphology. Sediment accretion has increased significantly in these areas as a result of sheltering by these deep-waterway structures. This review shows that human activities have severely altered the natural balance among the hydrodynamics and sediment supply, affecting the morphological features of the Yangtze River watershed and delta. Human impacts on the morphological evolution of deltaic coasts in general are becoming an increasingly concern, and more attention should be paid to the management and mitigation of these effects.
•This article descripts and evaluates the previous researches, and do some new exploration based on latest data.•Yangtze sediment discharge has declined greatly due to dam construction and soil conservation within the watersheds.•Decline in sediment supply has decreased progradation rate and triggered erosion in the delta front.•Reclamation and Deep Waterway Project have greatly affected morphological evolution in the estuary.
A process of NaOH molten salt roasting–water leaching to treat titanium–vanadium slag obtained by direct reduction of titanomagnetite concentrates was investigated. X-ray diffraction (XRD), scanning ...electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS), and thermogravimetry–differential scanning calorimetry (TG–DSC) techniques were used to characterize the samples. The results show that anosovite (Mg
x
Ti
3−
x
O
5
) and clinopyroxene Ca(Ti,MgAl)(SiAl)
2
O
6
are the major phases of titanium–vanadium slag. In the NaOH molten salt roasting process, titanium is converted to intermediate product Na
2
TiO
3
and vanadium is converted to water-soluble vanadate. The response surface methodology (RSM) was used to optimize the roasting process conditions. NaOH to slag mass ratio (N/S) and roasting temperature are the main influential factors. Under the optimal roasting conditions, i.e., roasting temperature of 550 °C, N/S of 1.20, and roasting time of 80 min, the conversions of titanium and vanadium are 96.5 % and 93.0 %, respectively. In the water leaching process, Na
2
TiO
3
is converted to amorphous structure of H
2
TiO
3
since Na
+
is exchanged with H
+
. Up to 93.0 % vanadium is leached out under the optimal leaching conditions. Titanium and vanadium in the titanium–vanadium slag can be separated and then recovered.
Capillary electrophoresis (CE) is widely used in forensic genetics to study short tandem repeats (STRs). Recently, next-generation sequencing (NGS) platforms have facilitated the development of new ...strategies for forensic DNA typing. Several studies have shown that NGS successfully analyzes challenging samples. However, because NGS is complicated and time-consuming, it remains unclear whether NGS platforms offer significant advantages over CE for all forensic cases. Here, the MiSeq FGx system was used to test some cases that had previously been analyzed using CE. These cases included paternity test cases in which some samples exhibited locus inconsistencies; samples with off-ladder (OL) alleles; samples with triallelic patterns; and samples with amelogenin test abnormalities. The results generated by MiSeq FGx were compared to those previously generated by CE. The MiSeq FGx and CE results were consistent with the exception of three samples, where inconsistencies were observed at the Penta D locus. For all three incongruent samples, the MiSeq FGx results were correct. Sequence analysis indicated that, in two cases, mismatches were due to undetected alleles rather than mutations. In two additional cases, mutation sources were identified, and in a fifth case, mutation step size was reconsidered. MiSeq FGx was used to identify OL alleles and samples with amelogenin test abnormalities. For cases where verification was required via CE analysis, the simultaneous NGS amplification of several types of multiple genetic markers improved testing efficiency. In addition, we identified additional sequence variants at autosomal, Y chromosomal, and X chromosomal STR loci in the Han Chinese population from northern China. Our results will be useful for future forensic analyses of STR genotypes in Chinese populations. It is likely that NGS would be more widely used in forensic genetics if costs and procedure complexity were reduced.
Major depressive disorder (MDD) has been increasingly understood as a disruption of brain connectome. Investigating grey matter structural networks with a large sample size can provide valuable ...insights into the structural basis of network-level neuropathological underpinnings of MDD.
Using a multisite MRI data-set including nearly 2000 individuals, this study aimed to identify robust topology and connectivity abnormalities of grey matter structural network linked to MDD and relevant clinical phenotypes.
A total of 955 MDD patients and 1009 healthy controls were included from 23 sites. Individualised structural covariance networks (SCN) were established based on grey matter volume maps. Following data harmonisation, network topological metrics and focal connectivity were examined for group-level comparisons, individual-level classification performance and association with clinical ratings. Various validation strategies were applied to confirm the reliability of findings.
Compared with healthy controls, MDD individuals exhibited increased global efficiency, abnormal regional centralities (i.e. thalamus, precentral gyrus, middle cingulate cortex and default mode network) and altered circuit connectivity (i.e. ventral attention network and frontoparietal network). First-episode drug-naive and recurrent patients exhibited different patterns of deficits in network topology and connectivity. In addition, the individual-level classification of topological metrics outperforms that of structural connectivity. The thalamus-insula connectivity was positively associated with the severity of depressive symptoms.
Based on this high-powered data-set, we identified reliable patterns of impaired topology and connectivity of individualised SCN in MDD and relevant subtypes, which adds to the current understanding of neuropathology of MDD and might guide future development of diagnostic and therapeutic markers.
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