134 research outputs found
Legendre Invariance and Geometrothermodynamics Description of the 3D Charged-Dilaton Black Hole
We first review Weinhold information geometry and Ruppeiner information geometry of 3D charged-dilaton black hole. Then, we use the Legendre invariant to introduce a 2-dimensional thermodynamic metric in the space of equilibrium states, which becomes singular at those points. According to the analysis of the heat capacities, these points are the places where phase transitions occur. This result is valid for the black hole, therefore, provides a geometrothermodynamics description of black hole phase transitions in terms of curvature singularities
Gaps and weaknesses in the global protected area network for safeguarding at-risk species
Protected areas are essential to biodiversity conservation. Creating new parks can protect larger populations and more species, yet strengthening existing parks, particularly those vulnerable to harmful human activities, is a critical but underappreciated step for safeguarding at-risk species. Here, we model the area of habitat that terrestrial mammals, amphibians, and birds have within park networks and their vulnerability to current downgrading, downsizing, or degazettement events and future land-use change. We find that roughly 70% of species analyzed have scant representation in parks, or occur within parks that are affected by shifts in formal legal protections or are vulnerable to increased human pressures. Our results also show that expanding and strengthening park networks across just 1% of the world’s land area could preserve irreplaceable habitats of 1191 species that are particularly vulnerable to extinction
Occurrence-habitat mismatching and niche truncation when modelling distributions affected by anthropogenic range contractions
Aims Human-induced pressures such as deforestation cause anthropogenic range contractions (ARCs). Such contractions present dynamic distributions that may engender data misrepresentations within species distribution models. The temporal bias of occurrence data-where occurrences represent distributions before (past bias) or after (recent bias) ARCs-underpins these data misrepresentations. Occurrence-habitat mismatching results when occurrences sampled before contractions are modelled with contemporary anthropogenic variables; niche truncation results when occurrences sampled after contractions are modelled without anthropogenic variables. Our understanding of their independent and interactive effects on model performance remains incomplete but is vital for developing good modelling protocols. Through a virtual ecologist approach, we demonstrate how these data misrepresentations manifest and investigate their effects on model performance. Location Virtual Southeast Asia. Methods Using 100 virtual species, we simulated ARCs with 100-year land-use data and generated temporally biased (past and recent) occurrence datasets. We modelled datasets with and without a contemporary land-use variable (conventional modelling protocols) and with a temporally dynamic land-use variable. We evaluated each model's ability to predict historical and contemporary distributions. Results Greater ARC resulted in greater occurrence-habitat mismatching for datasets with past bias and greater niche truncation for datasets with recent bias. Occurrence-habitat mismatching prevented models with the contemporary land-use variable from predicting anthropogenic-related absences, causing overpredictions of contemporary distributions. Although niche truncation caused underpredictions of historical distributions (environmentally suitable habitats), incorporating the contemporary land-use variable resolved these underpredictions, even when mismatching occurred. Models with the temporally dynamic land-use variable consistently outperformed models without. Main conclusions We showed how these data misrepresentations can degrade model performance, undermining their use for empirical research and conservation science. Given the ubiquity of ARCs, these data misrepresentations are likely inherent to most datasets. Therefore, we present a three-step strategy for handling data misrepresentations: maximize the temporal range of anthropogenic predictors, exclude mismatched occurrences and test for residual data misrepresentations.Peer reviewe
Heteroaromatic organic compound with conjugated multi-carbonyl as cathode material for rechargeable lithium batteries
The heteroaromatic organic compound, N,N\u27-diphenyl-1,4,5,8-naphthalenetetra-carboxylic diimide (DP-NTCDI-250) as the cathode material of lithium batteries is prepared through a simple one-pot N-acylation reaction of 1,4,5,8-naphthalenetetra-carboxylic dianhydride (NTCDA) with phenylamine (PA) in DMF solution followed by heat treatment in 250 °C. The as prepared sample is characterized by the combination of elemental analysis, NMR, FT-IR, TGA, XRD, SEM and TEM. The electrochemical measurements show that DP-NTCDI-250 can deliver an initial discharge capacity of 170 mAh g-1 at the current density of 25 mA g-1. The capacity of 119 mAh g-1 can be retained after 100 cycles. Even at the high current density of 500 mA g-1, its capacity still reaches 105 mAh g-1, indicating its high rate capability. Therefore, the as-prepared DP-NTCDI-250 could be a promising candidate as low cost cathode materials for lithium batteries
On the special oxidation mechanism of a Mg-Y-Al alloy contained LPSO phase at high temperatures
This work investigated the oxidation of Mg-11Y-1Al alloy in Ar-20%O2 at
500{\deg}through multiscale characterization. The results show that the
network-like long-period stacking ordered(LPSO) phase decomposed into a
needle-like LPSO phase and a polygonal Mg24Y5 phase. The needle-like LPSO phase
resulted in the formation of a high-dense of needle-like oxide at the oxidation
front of the area initially occupied by the network-like LPSO phase. The
further inward oxygen would diffuse along the needle-like oxide-matrix
interfaces and react with Y in the surrounding Mg matrix, resulting in the
lateral growth of these needle-like oxides. Finally, the discrete needle-like
oxides were interconnected to form a thicker and continuous oxide scale which
could be more effective in hindering the elemental diffusion. Meanwhile, Al
could partially enter the Y2O3 oxide scale and formed a strengthened (Y,Al)O
oxide scale which could show a greater resistance to cracking and debonding
Nonreciprocal charge transport in the titanium sesquioxide heterointerface superconductor
Nonreciprocal charge transport in heterostructural superconductors exhibits
appealing quantum physical phenomena and holds the promising potential for
superconducting circuits applications. Realizing a nonreciprocity is, however,
fundamentally and technologically challenging, as it requires a material
structure without a centre of inversion, which is scarce among superconducting
materials. Here, we report an evidence of helical superconductivity, in which
the Rashba spin-orbit coupling induces momentum-dependent superconducting gap
in the inversion symmetry breaking heterointerface superconductor consisting of
Mott insulating TiO and polar semiconducting GaN. Remarkably, the
nonlinear responses emerge in the superconducting transition regime, when the
magnetic field is precisely aligned in-plane orientations perpendicular to the
applied current. In particular, the observed nonreciprocal supercurrent is
extremely sensitive to the direction of the magnetic field for 0.5 degree,
suggestive of a crossover from a symmetry breaking state to a symmetric one.
Our finding not only unveils the underlying rich physical properties in
heterointerface superconductors, but also provides an exciting opportunity for
the development of novel mesoscopic superconducting devices
Doing housework and having regular daily routine standing out as factors associate with physical function in the older people
Background and objectivesNationwide data were used to explore factors associated with physical function in order to identify interventions that could improve and maintain physical function in the older people.MethodsThe physical function was assessed by gait speed (GS). We selected 2,677 male and 2,668 female older adults (aged ≥60) who could perform the GS test as study subjects. GS was measured by having subjects walk across and back a 10-m course. A gait speed less than 20% that of a reference population (<0.7 m/s) was used as the definition of slow gait speed (SGS). Co-morbidity, polypharmacy, medical expenses, need for care, and hospitalization were used to evaluate health status. A stepwise logistic regression model was used to determine factors associated with SGS.ResultsSGS was associated with poorer health status, higher medical cost, lower ranking on the Geriatric Depression Scale (GDS) and decreased Mini-mental State Examination (MMSE). Co-morbidity (OR = 1.81, 1.58–2.07), polypharmacy (OR = 1.47, 1.25–1.74), MMSE <24 (OR = 1.85, 1.54–2.22), and GDS ≥ 11 (OR = 1.40, 1.18–1.65) were associated with SGS. In contrast, doing housework (DHW, OR = 0.43, 0.38–0.49), having a regular daily routine (RDR, OR = 0.64, 0.45–0.91), and current alcohol consumption (OR = 0.74, 0.62–0.90) were inversely associated with SGS. DHW plus having RDR could greatly reduce the risk of SGS (OR = 0.29, 0.19–0.43).ConclusionPoor physical function is associated with poorer health status in Chinese older people. Maintaining a regular daily routine and doing some housework may be important factors that can help older people preserve their physical function
Myeloid cell-derived LL-37 promotes lung cancer growth by activating Wnt/β-catenin signaling
Rationale: Antimicrobial peptides, such as cathelicidin LL-37/hCAP-18, are important effectors of the innate
immune system with direct antibacterial activity. In addition, LL-37 is involved in the regulation of tumor cell
growth. However, the molecular mechanisms underlying the functions of LL-37 in promoting lung cancer are
not fully understood.
Methods: The expression of LL-37 in the tissues and sera of patients with non-small cell lung cancer was
determined through immunohistological, immunofluorescence analysis, and enzyme-linked immunosorbent
assay. The animal model of wild-type and Cramp knockout mice was employed to evaluate the tumorigenic
effect of LL-37 in non-small cell lung cancer. The mechanism of LL-37 involving in the promotion of lung tumor
growth was evaluated via microarray analyses, recombinant protein treatment approaches in vitro, tumor
immunohistochemical assays, and intervention studies in vivo.
Results: LL-37 produced by myeloid cells was frequently upregulated in primary human lung cancer tissues.
Moreover, its expression level correlated with poor clinical outcome. LL-37 activated Wnt/β-catenin signaling
by inducing the phosphorylation of protein kinase B and subsequent phosphorylation of glycogen synthase
kinase 3β mediated by the toll-like receptor-4 expressed in lung tumor cells. LL-37 treatment of tumor cells
also decreased the levels of Axin2. In contrast, it elevated those of an RNA-binding protein (tristetraprolin),
which may be involved in the mechanism through which LL-37 induces activation of Wnt/β-catenin.
Conclusion: LL-37 may be a critical molecular link between tumor-supportive immune cells and tumors,
facilitating the progression of lung cancer
Proximity effect induced intriguing superconductivity in van der Waals heterostructure of magnetic topological insulator and conventional superconductor
Nontrivial topological superconductivity has received enormous research
attentions due to its potential for diverse applications in topological quantum
computing. The intrinsic issue concerning the correlation between a topological
insulator and a superconductor is, however, still widely open. Here, we
systemically report an emergent superconductivity in a cross-junction composed
of a magnetic topological insulator MnBi2Te4 and a conventional superconductor
NbSe2. Remarkably, the interface indicates existence of a reduced
superconductivity at surface of NbSe2 and a proximity-effectinduced
superconductivity at surface of MnBi2Te4. Furthermore, the in-plane
angular-dependent magnetoresistance measurements reveal the fingerprints of the
paring symmetry behaviors for these superconducting gaps as a unconventional
nature. Our findings extend our views and ideas of topological
superconductivity in the superconducting heterostructures with time-reversal
symmetry breaking, offering an exciting opportunity to elucidate the
cooperative effects on the surface state of a topological insulator aligning a
superconductor.Comment: 6 pages, 4 figure
Neuroprotective Mechanisms of Lycium barbarum Polysaccharides Against Ischemic Insults by Regulating NR2B and NR2A Containing NMDA Receptor Signaling Pathways
Glutamate excitotoxicity plays an important role in neuronal death after ischemia. However, all clinical trials using glutamate receptor inhibitors have failed. This may be related to the evidence that activation of different subunit of NMDA receptor will induce different effects. Many studies have shown that activation of the intrasynaptic NR2A subunit will stimulate survival signaling pathways, whereas upregulation of extrasynaptic NR2B will trigger apoptotic pathways. A Lycium barbarum polysaccharide (LBP) is a mixed compound extracted from Lycium barbarum fruit. Recent studies have shown that LBP protects neurons against ischemic injury by anti-oxidative effects. Here we first reported that the effect of LBP against ischemic injury can be achieved by regulating NR2B and NR2A signaling pathways. By in vivo study, we found LBP substantially reduced CA1 neurons from death after transient global ischemia and ameliorated memory deficit in ischemic rats. By in vitro study, we further confirmed that LBP increased the viability of primary cultured cortical neurons when exposed to oxygen-glucose deprivation (OGD) for 4 h. Importantly, we found that LBP antagonized increase in expression of major proteins in the NR2B signal pathway including NR2B, nNOS, Bcl-2-associated death promoter (BAD), cytochrome C (cytC) and cleaved caspase-3, and also reduced ROS level, calcium influx and mitochondrial permeability after 4 h OGD. In addition, LBP prevented the downregulation in the expression of NR2A, pAkt and pCREB, which are important cell survival pathway components. Furthermore, LBP attenuated the effects of a NR2B co-agonist and NR2A inhibitor on cell mortality under OGD conditions. Taken together, our results demonstrated that LBP is neuroprotective against ischemic injury by its dual roles in activation of NR2A and inhibition of NR2B signaling pathways, which suggests that LBP may be a superior therapeutic candidate for targeting glutamate excitotoxicity for the treatment of ischemic stroke
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