The prediction of an image quality metric (IQM) should be consistent with subjective human evaluation. As the human visual system (HVS) is critical to visual perception, modeling of the HVS is ...regarded as the most suitable way to achieve perceptual quality predictions. Sparse coding that is equivalent to independent component analysis (ICA) can provide a very good description of the receptive fields of simple cells in the primary visual cortex, which is the most important part of the HVS. With this inspiration, a quality metric called sparse feature fidelity (SFF) is proposed for full-reference image quality assessment (IQA) on the basis of transformation of images into sparse representations in the primary visual cortex. The proposed method is based on the sparse features that are acquired by a feature detector, which is trained on samples of natural images by an ICA algorithm. In addition, two strategies are designed to simulate the properties of the visual perception: 1) visual attention and 2) visual threshold. The computation of SFF has two stages: training and fidelity computation, in addition, the fidelity computation consists of two components: feature similarity and luminance correlation. The feature similarity measures the structure differences between the two images, whereas the luminance correlation evaluates brightness distortions. SFF also reflects the chromatic properties of the HVS, and it is very effective for color IQA. The experimental results on five image databases show that SFF has a better performance in matching subjective ratings compared with the leading IQMs.
To optimally penetrate biological hydrogels such as mucus and the tumor interstitial matrix, nanoparticles (NPs) require physicochemical properties that would typically preclude cellular uptake, ...resulting in inefficient drug delivery. Here, we demonstrate that (poly(lactic-co-glycolic acid) (PLGA) core)-(lipid shell) NPs with moderate rigidity display enhanced diffusivity through mucus compared with some synthetic mucus penetration particles (MPPs), achieving a mucosal and tumor penetrating capability superior to that of both their soft and hard counterparts. Orally administered semi-elastic NPs efficiently overcome multiple intestinal barriers, and result in increased bioavailability of doxorubicin (Dox) (up to 8 fold) compared to Dox solution. Molecular dynamics simulations and super-resolution microscopy reveal that the semi-elastic NPs deform into ellipsoids, which enables rotation-facilitated penetration. In contrast, rigid NPs cannot deform, and overly soft NPs are impeded by interactions with the hydrogel network. Modifying particle rigidity may improve the efficacy of NP-based drugs, and can be applicable to other barriers.
Aerogel composites are multicomponent highly porous materials with air as the major dispersed phase. There are many kinds of aerogel composites including synthetic and natural aerogel composites. ...Aerogel composites have found wide applications in sorption, thermal insulation, vibration damping, and noise control. This mini review focuses on the aerogel composites with oil water separation function for spilled oil cleaning. The design and fabrication of various aerogel composites for oil cleaning are emphasized. The commonly used technologies including in-situ reaction, sol–gel spinning, templating, and self-assembling are introduced. The microstructure control through directional freeze casting, bio-inspired approach, coating, etc., are discussed.
This paper deals with the effect of interface structures on the mechanical properties of fiber reinforced composite materials. First, the background of research, development and applications on ...hybrid composite materials is introduced. Second, metal/polymer composite bonded structures are discussed. Then, the rationale is given for nanostructuring the interface in composite materials and structures by introducing nanoscale features such as nanopores and nanofibers. The effects of modifying matrices and nano-architecturing interfaces on the mechanical properties of nanocomposite materials are examined. A nonlinear damage model for characterizing the deformation behavior of polymeric nanocomposites is presented and the application of this model to carbon nanotube-reinforced and reactive graphite nanotube-reinforced epoxy composite materials is shown.
High‐entropy metal diborides (Hf0.2Zr0.2Ta0.2M0.2Ti0.2)B2 (M = Nb, Mo, Cr) are a new class of ultrahigh temperature ceramics. The novel structural, mechanical, and electronic properties of ...(Hf0.2Zr0.2Ta0.2M0.2Ti0.2)B2 (M = Nb, Mo, Cr) are studied within density functional theory, with the compositional disorder being treated using the special quasi‐random structures technique. The elastic stiffness constants Cij, as well as bulk, shear and Young's modulus of (Hf0.2Zr0.2Ta0.2M0.2Ti0.2)B2 (M = Nb, Mo, Cr) are studied to estimate the mechanical properties. The ductility is also investigated from several criterions, showing that (Hf0.2Zr0.2Ta0.2M0.2Ti0.2)B2 (M = Nb, Mo, Cr) is still intrinsically brittle. The high Debye temperature of (Hf0.2Zr0.2Ta0.2M0.2Ti0.2)B2 (M = Nb, Mo, Cr) indicates the strong interatomic interactions and good thermal conductivity. The detailed investigations of electronic structure reveal that covalent and metallic bonds are respectively formed in the boron layer and the metal layer, mixed ionic and covalent bonds are formed between the metals and boron interlayer.
The high‐entropy ceramics (Hf0.2Zr0.2Ta0.2M0.2Ti0.2)B2 (M = Nb, Mo, Cr) are stable thermodynamically and mechanically. The elastic modulus follows the mixing rule. (Hf0.2Zr0.2Ta0.2M0.2Ti0.2)B2 (M = Nb, Mo, Cr) possess higher Debye temperature. They exhibit a combination of metallic, covalent and ionic bonding. Mechanical properties of (Hf0.2Zr0.2Ta0.2Nb0.2Ti0.2)B2 are more excellent than (Hf0.2Zr0.2Ta0.2M0.2Ti0.2)B2 (M = Mo, Cr).
The stacking of monolayers in the form of van der Waals heterostructures is a useful strategy for band gap engineering and the control of dynamics of excitons for potential nano-electronic devices. ...We performed first-principles calculations to investigate the structural, electronic, optical and photocatalytic properties of the SiC-MX
2
(M = Mo, W and X = S, Se) van der Waals heterostructures. The stability of most favorable stacking is confirmed by calculating the binding energy and phonon spectrum. SiC-MoS
2
is found to be a direct band gap type-II semiconducting heterostructure. Moderate in-plane tensile strain is used to achieve a direct band gap with type-II alignment in the SiC-WS
2
, SiC-MoSe
2
and SiC-WSe
2
heterostructures. A difference in the ionization potential of the corresponding monolayers and interlayer charge transfer further confirmed the type-II band alignment in these heterostructures. Furthermore, the optical behaviour is investigated by calculation of the absorption spectra in terms of
2
(
ω
) of the heterostructures and the corresponding monolayers. The photocatalytic response shows that the SiC-Mo(W)S
2
heterostructures can oxidize H
2
O to O
2
. An enhanced photocatalytic performance with respect to the parent monolayers makes the SiC-Mo(W)Se
2
heterostructures promising candidates for water splitting.
The stacking of monolayers in the form of van der Waals heterostructures is a useful strategy for band gap engineering and the control of dynamics of excitons for potential nano-electronic devices.
In this work, a carbon network/aluminum matrix composite material was made by the powder metallurgical approach. Pure aluminum powders with a diameter of less than 30 μm were compressed with sugar ...particles with the similar size under a pressure of 40 MPa. Sintering at 500 °C in pure argon gas for 2 h was performed to carbonize the sugar. After the sintered product was cooled down, microstructure analysis was carried out. It was found that high temperature sintering allowed the material to generate carbon networks distributed along the grain boundaries in the porous aluminum. An aluminum to sugar ratio of 1 to 1 reached the maximum carbon concentration in the composite for keeping the structural integrity. Characterization of the corrosion behaviors of the carbon network/porous aluminum composite material and a pure aluminum plate in seawater was conducted by measuring their Tafel plots. The Galvanic potential of the carbon network/porous aluminum composite material is about -0.62 V. The pure aluminum shows a more negative Galvanic potential of -0.755 V. As compared with pure aluminum, the composite material showed improvement on the corrosion property. The corrosion current of the composite in seawater is about 100 times lower than that of the pure aluminum. The existence of carbon network in the composite and the oxidized state of the sintered aluminum allows the composite material to be more corrosion resistant in seawater. For the materials processed with higher sugar content (with Al: sugar ratio of 1:1.25), carbon became the dominant phase in the composite. The material has a low strength and ease to get collapsed. The corrosion behavior of the composite made from low Al to sugar ratio raw material is similar to that of the one with Al: sugar ratio of 1:1. For the high carbon content composite material with Al: sugar ratio of 1:1.25, the Galvanic potential of the material is as high as -0.32 V, which is very close to the Galvanic potential of graphite in seawater. It shows the corrosion behavior of pure carbon in seawater.
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•C/Al composites can be made by powder metallurgy.•Structure analysis reveals carbon networks along grain boundaries.•Al is slightly oxidized to form alumina nanoparticles dispersed in grains.•The C/Al composite material is more corrosion resistant than Al in seawater.
Using first-principles calculations, we predict a family group of two-dimensional semimetals MX (M = Pd, Pt; X = S, Se, Te), which has a zig-zag type mono-layer structure in the
Pmma
(no. 41) layer ...group. Band structure analysis reveals that node-line features are caused by band inversion and the inversion exists even in the absence of spin-orbital-coupling. First-principles calculations show the robust lattice stability of these predicted materials. This work provides the possibility of making a group of novel two-dimensional materials with semimetal features.
Using first-principles calculations, we predict a family group of two-dimensional semimetals MX (M = Pd, Pt; X = S, Se, Te), which has a zig-zag type mono-layer structure in the
Pmma
(no. 41) layer group.
Effective management of dyslipidemia is important. This study aimed to determine the awareness, treatment, control, and determinants of dyslipidemia in middle-aged and older Chinese adults in China. ...Using data from the 2015 China National Stroke Screening and Prevention Project (CNSSPP), a nationally representative sample of 135,403 Chinese adults aged 40 years or more were included in this analysis. Dyslipidemia was defined by the Third Report of the National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults final report (NCEP-ATP III) and the 2016 Chinese guidelines for the management of dyslipidemia in adults. Models were constructed to adjust for subjects' characteristics with bivariate and multivariable logistic regression analyses. Overall, 51.1% of the subjects were women. Sixty-four percent were aware of their condition, of whom 18.9% received treatment, and of whom 7.2% had adequately controlled dyslipidemia. Dyslipidemia treatment was higher in men from rural areas than their urban counterparts. The multivariable logistic regression models revealed that women, urban residents, and general obesity were positively related to awareness. Women, married respondents, and current drinkers had higher odds of treatment. Age group, overweight, general obesity, urban residence, and women were independent determinants of control. Dyslipidemia awareness rate was moderately high, but treatment and control rates were low. Results can be used to develop policies and health promotion strategies with special focus on middle-aged and older adults.
Mucus is a viscoelastic gel layer that typically protects exposed surfaces of the gastrointestinal (GI) tract, lung airways, and other mucosal tissues. Particles targeted to these tissues can be ...efficiently trapped and removed by mucus, thereby limiting the effectiveness of such drug delivery systems. In this study, we experimentally and theoretically demonstrated that cylindrical nanoparticles (NPs), such as mesoporous silica nanorods and calcium phosphate nanorods, have superior transport and trafficking capability in mucus compared with spheres of the same chemistry. The higher diffusivity of nanorods leads to deeper mucus penetration and a longer retention time in the GI tract than that of their spherical counterparts. Molecular simulations and stimulated emission of depletion (STED) microscopy revealed that this anomalous phenomenon can be attributed to the rotational dynamics of the NPs facilitated by the mucin fibers and the shear flow. These findings shed new light on the shape design of NP-based drug delivery systems targeted to mucosal and tumor sites that possess a fibrous structure/porous medium.
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