We propose a deep bilinear model for blind image quality assessment that works for both synthetically and authentically distorted images. Our model constitutes two streams of deep convolutional ...neural networks (CNNs), specializing in two distortion scenarios separately. For synthetic distortions, we first pre-train a CNN to classify the distortion type and the level of an input image, whose ground truth label is readily available at a large scale. For authentic distortions, we make use of a pre-train CNN (VGG-16) for the image classification task. The two feature sets are bilinearly pooled into one representation for a final quality prediction. We fine-tune the whole network on the target databases using a variant of stochastic gradient descent. The extensive experimental results show that the proposed model achieves state-of-the-art performance on both synthetic and authentic IQA databases. Furthermore, we verify the generalizability of our method on the large-scale Waterloo Exploration Database, and demonstrate its competitiveness using the group maximum differentiation competition methodology.
Recent observation of intrinsic ferromagnetism in two-dimensional (2D) CrI3 is associated with the large magnetic anisotropy due to strong spin-orbit coupling of I. Magnetic anisotropy energy (MAE) ...defines the stability of magnetization in a specific direction with respect to the crystal lattice and is an important parameter for nanoscale applications. In this work we apply the density functional theory to study the strain dependence of MAE in 2D monolayer chromium trihalides CrX3 (with X = Cl, Br, and I). Detailed calculations of their energetics, atomic structures, and electronic structures under the influence of a biaxial strain ɛ have been carried out. It is found that all three compounds exhibit ferromagnetic ordering at the ground state (with ɛ=0), and upon applying a compressive strain, phase transition to the antiferromagnetic state occurs. Unlike in CrCl3 and CrBr3, the electronic band gap in CrI3 increases when a tensile strain is applied. The MAE also exhibits a strain dependence in the chromium trihalides: it increases when a compressive strain is applied in CrI3, while an opposite trend is observed in the other two compounds. In particular, the MAE of CrI3 can be increased by 47% with a compressive strain of ɛ = 5%.
Pancreatic cancer is an increasingly common cause of cancer mortality with a tight correspondence between disease mortality and incidence. Furthermore, it is usually diagnosed at an advanced stage ...with a very dismal prognosis. Due to the high heterogeneity, metabolic reprogramming, and dense stromal environment associated with pancreatic cancer, patients benefit little from current conventional therapy. Recent insight into the biology and genetics of pancreatic cancer has supported its molecular classification, thus expanding clinical therapeutic options. In this review, we summarize how the biological features of pancreatic cancer and its metabolic reprogramming as well as the tumor microenvironment regulate its development and progression. We further discuss potential biomarkers for pancreatic cancer diagnosis, prediction, and surveillance based on novel liquid biopsies. We also outline recent advances in defining pancreatic cancer subtypes and subtype-specific therapeutic responses and current preclinical therapeutic models. Finally, we discuss prospects and challenges in the clinical development of pancreatic cancer therapeutics.
We apply the density-functional theory to study various phases (including non-magnetic (NM), anti-ferromagnetic (AFM), and ferromagnetic (FM)) in monolayer magnetic chromium triiodide (CrI3), a ...recently fabricated 2D magnetic material. It is found that: (1) the introduction of magnetism in monolayer CrI3 gives rise to metal-to-semiconductor transition; (2) the electronic band topologies as well as the nature of direct and indirect band gaps in either AFM or FM phases exhibit delicate dependence on the magnetic ordering and spin–orbit coupling; and (3) the phonon modes involving Cr atoms are particularly sensitive to the magnetic ordering, highlighting distinct spin–lattice and spin–phonon coupling in this magnet. First-principles simulations of the Raman spectra demonstrate that both frequencies and intensities of the Raman peaks strongly depend on the magnetic ordering. The polarization dependent A1g modes at 77 cm−1 and 130 cm−1 along with the Eg mode at about 50 cm−1 in the FM phase may offer a useful fingerprint to characterize this material. Our results not only provide a detailed guiding map for experimental characterization of CrI3, but also reveal how the evolution of magnetism can be tracked by its lattice dynamics and Raman response.
The key issue holding back the application of solid polymeric electrolytes in high‐energy density lithium metal batteries is the contradictory requirements of high ion conductivity and mechanical ...stability. In this work, self‐healable solid polymeric electrolytes (SHSPEs) with rigid‐flexible backbones and high ion conductivity are synthesized by a facile condensation polymerization approach. The all‐solid Li metal full batteries based on the SHSPEs possess freely bending flexibility and stable cycling performance as a result of the more disciplined metal Li plating/stripping, which have great implications as long‐lifespan energy sources compatible with other wearable devices.
Solid but flexible: A self‐healing solid polymer electrolyte (featuring fast self‐healing within 60 s after a deep cut with a blade) endows solid Li metal full batteries with freely bending flexibility and superior cycling stability as demonstrated by the small capacity decay of 0.1 % per cycle over 100 cycles.
Integrating simultaneous wireless information and power transfer (SWIPT) into cooperative cognitive radio networks (CCRN) can increase both energy and spectral efficiencies. In contrast to most of ...existing works that consider only relay transmission, this paper studies opportunistic relaying along with dynamic energy harvesting in SWIPT-based CCRN, where a secondary transmitter (ST) can act as relay for primary transmission and a secondary receiver (SR) has the energy harvesting function. We propose a new framework that can unify the direct transmission, relay transmission and energy harvesting. Under the proposed framework, we first assume the transmit power of the ST is fixed and formulate the optimization problem of maximizing the ergodic capacity for SR while meeting the ergodic capacity for the primary receiver and average harvested energy for SR, by joint transmission mode selection and transmit power splitting ratio selection. Then, for the case when the transmit power of the ST can be adjusted, we investigate the joint optimization of transmit power control, transmit power splitting ratio, and transmission mode selection. The two problems are nonconvex and we propose the optimal policies by using the dual Lagrangian method. Simulations validate the effectiveness of the proposed schemes.
Lithium‐rich layered oxides with the capability to realize extraordinary capacity through anodic redox as well as classical cationic redox have spurred extensive attention. However, the ...oxygen‐involving process inevitably leads to instability of the oxygen framework and ultimately lattice oxygen release from the surface, which incurs capacity decline, voltage fading, and poor kinetics. Herein, it is identified that this predicament can be diminished by constructing a spinel Li4Mn5O12 coating, which is inherently stable in the lattice framework to prevent oxygen release of the lithium‐rich layered oxides at the deep delithiated state. The controlled KMnO4 oxidation strategy ensures uniform and integrated encapsulation of Li4Mn5O12 with structural compatibility to the layered core. With this layer suppressing oxygen release, the related phase transformation and catalytic side reaction that preferentially start from the surface are consequently hindered, as evidenced by detailed structural evolution during Li+ extraction/insertion. The heterostructure cathode exhibits highly competitive energy‐storage properties including capacity retention of 83.1% after 300 cycles at 0.2 C, good voltage stability, and favorable kinetics. These results highlight the essentiality of oxygen framework stability and effectiveness of this spinel Li4Mn5O12 coating strategy in stabilizing the surface of lithium‐rich layered oxides against lattice oxygen escaping for designing high‐performance cathode materials for high‐energy‐density lithium‐ion batteries.
A heterostructured spinel Li4Mn5O12 encapulated lithium‐rich layered oxide cathode is designed by the controlled KMnO4 oxidiation strategy. Spinel Li4Mn5O12 is chosen due to its lattice stability against oxygen release as well as a 3D lithium diffusion framework with minimal Jahn–Teller distortion. Such uniform coating can suppress lattice oxygen release, associated phase transformation, and catalytic side reactions, consequently ensuring improved electrochemical performance.
Witnessed by the rapid increase of power conversion efficiency to 25.5%, organic–inorganic hybrid perovskite solar cells (PSCs) are becoming promising candidates of next‐generation photovoltaics. ...However, PSCs can be unstable under the influence of light and bias. Especially, grain boundaries (GBs) are vulnerable to attack by light and bias in perovskite films, leading to degradation of photovoltaic properties of PSCs. Herein, photocurrent atomic force microscopy and Kelvin probe force microscopy are employed to systematically investigate the bias‐dependent charge transport behaviors and stability of (FAPbI3)0.85(MAPbBr3)0.15 perovskite under working condition. Bias‐dependent morphology and photocurrent images show irreversible decomposition of the perovskite at a bias of 0.1 V or below, which is accelerated by light illumination, leading to formation of an interfacial layer that restricts carrier transport. Meanwhile, GBs appear to enhance carrier transport at larger bias, but serve as breakthrough sites for perovskite decomposition at smaller bias. Introducing excess methylammonium iodide promotes decomposition, while potassium iodide passivation greatly relieves the decomposition. These results support the ion migration mechanism of decomposition through interfaces and GBs. This work provides a deeper understanding of bias‐induced degradation of PSCs as well as bias‐dependent double‐edged roles of GBs, and forms valuable guidance for appropriate operation of PSCs.
Bias‐dependent stability of (FAPbI3)0.85(MAPbBr3)0.15 perovskite and double‐edged roles of grain boundaries in carrier transport and degradation of solar cells under working condition are systematically investigated. Photocurrent atomic force microscopy results show that grain boundaries enhance carrier transport at larger bias, but serve as breakthrough sites at smaller bias of 0.1 V or below when irreversible decomposition of perovskite occurs.
Sleep control is ascribed to a two-process model, a widely accepted concept that posits homoeostatic drive and a circadian process as the major sleep-regulating factors. Cognitive and emotional ...factors also influence sleep-wake behaviour; however, the precise circuit mechanisms underlying their effects on sleep control are unknown. Previous studies suggest that adenosine has a role affecting behavioural arousal in the nucleus accumbens (NAc), a brain area critical for reinforcement and reward. Here, we show that chemogenetic or optogenetic activation of excitatory adenosine A
receptor-expressing indirect pathway neurons in the core region of the NAc strongly induces slow-wave sleep. Chemogenetic inhibition of the NAc indirect pathway neurons prevents the sleep induction, but does not affect the homoeostatic sleep rebound. In addition, motivational stimuli inhibit the activity of ventral pallidum-projecting NAc indirect pathway neurons and suppress sleep. Our findings reveal a prominent contribution of this indirect pathway to sleep control associated with motivation.In addition to circadian and homoeostatic drives, motivational levels influence sleep-wake cycles. Here the authors demonstrate that adenosine receptor-expressing neurons in the nucleus accumbens core that project to the ventral pallidum are inhibited by motivational stimuli and are causally involved in the control of slow-wave sleep.
Given the comparatively lower rotational barriers, the catalytic asymmetric construction of axially chiral biaryl structures, especially those containing a five‐membered heterocycle, still remains a ...challenge. Herein, we described a general and modular protocol to access atropisomeric arylpyrazole scaffolds containing a phosphorus unit by a dipeptide phosphonium salt catalyzed reaction involving an oxidative central‐to‐axial chirality conversion. This reaction features excellent yields and enantioselectivities, broad substrate scope, and a low catalyst loading, delivering axially chiral phosphine compounds.
A highly enantioselective reaction has been developed for the construction of axially chiral arylpyrazole skeletons with phosphorus unit. The reaction proceeds through a sequential Huisgen‐type cycloaddition/aromatization process with central‐to‐axial chirality conversion using a dipeptide‐phosphonium salt catalyst. Arylpyrazole‐based atropisomeric phosphorus compounds are obtained in high yields with excellent enantioselectivities.
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