This paper proposes a general weighted l(2)-l(0) norms energy minimization model to remove mixed noise such as Gaussian-Gaussian mixture, impulse noise, and Gaussian-impulse noise from the images. The approach is built upon maximum likelihood estimation framework and sparse representations over a trained dictionary. Rather than optimizing the likelihood functional derived from a mixture distribution, we present a new weighting data fidelity function, which has the same minimizer as the original likelihood functional but is much easier to optimize. The weighting function in the model can be determined by the algorithm itself, and it plays a role of noise detection in terms of the different estimated noise parameters. By incorporating the sparse regularization of small image patches, the proposed method can efficiently remove a variety of mixed or single noise while preserving the image textures well. In addition, a modified K-SVD algorithm is designed to address the weighted rank-one approximation. The experimental results demonstrate its better performance compared with some existing methods.

stretchable polymeric materials include the use of double networks, [4][5][6] nanocomposites, [7] and dynamic polymer networks. [8][9][10][11][12][13][14][15][16][17] Among these strategies, dynamic polymer networks based on dynamic crosslinks such as hydrophobic association, [8] metal-ligand interactions, [9,10] host-guest interactions, [11] dynamic covalent bonds, [12] ion-dipole interactions, [13] hydrogen bonds, [14][15][16] and ion bonds [17] have attracted much attention. Compared with traditional covalent bonds, these dynamic crosslinks can effectively dissipate energy via reversible bond formation/scission or exchange reactions, [9,12,18] resulting in highly stretchable polymeric materials. Despite this progress, the construction of dynamic polymer networks with a stretching ratio beyond 1000× remains a great challenge. Here, we report the preparation of superstretchable polymer networks by using two types of dynamic bonds. We utilize a small number of strong crosslinks to maintain the network integrity during stretching and a large number of weak crosslinks to dissipate energy. We found that the synergetic interplay between these two mechanisms resulted in a superstretchable polymer network that could be stretched to more than 10 000× its original length.Specifically, polybutadiene (PB) networks crosslinked by ionic hydrogen bonds and imine bonds were prepared and examined. PB oligomers (liquid state, M w = 9400) were functionalized by amine and carboxyl groups via a thiol-ene reaction to obtain PB-NH 2 -9.8% and PB-COOH-5%, respectively (the number indicates the degree of functionalization; Figure S1 and Table S1, Supporting Information). Oligomeric PB was chosen because of the abundant vinyl double bonds (90% 1,2-addition) available for amine and carboxyl modification. PB-NH 2 -9.8% and PB-COOH-5% could be completely dissolved, and gel permeation chromatography (GPC) analysis showed that M w of the functionalized PB was similar to that of the original PB, revealing that no chemical crosslinking occurred during the thiol-ene reaction ( Figure S2, Supporting Information). Then, PB-NH 2 -9.8%, PB-COOH-5%, and benezene-1,3,5-tricarbaldehyde were mixed at different ratios. In this formulation, crosslinked polymer networks were constructed via the weak ionic hydrogen bonds between the amine and carboxyl groups and the strong imine bonds from the reaction of amine and aldehyde groups (Figure 1; Movie S1, Supporting Information). [19,20] PB networks with fixed crosslink degrees at 9.8%, but varied ratios and different orders of formation of the ionic hydrogen bonds and imine bonds, were prepared. The resultant networks were labeled PB-ion-imine-x-y and PB-imine-ion-y-x, where x and y indicate the concentration Superstretchable materials have many applications in advanced technological fields but are difficult to stretch to more than 1000× their original length. A superstretchable dynamic polymer network that can be stretched to 13 000× its original length is designed. It is revealed that superstretchability of...

In this article, we introduce a multimodal multivariate network analysis to characterize the linkage between the patterns of information from the same individual's complementary brain images, and illustrate its potential by showing its ability to distinguish older from younger adults with greater power than several previously established methods. Our proposed method uses measurements from every brain voxel in each person's complementary co-registered images and uses the partial least square (PLS) algorithm to form a combined latent variable that maximizes the covariance among all of the combined variables. It represents a new way to calculate the singular value decomposition from the high-dimensional covariance matrix in a computationally feasible way. Analyzing fluorodeoxyglucose positron emission tomography (PET) and volumetric magnetic resonance imaging (MRI) images, this method distinguished 14 older adults from 15 younger adults (p = 4e-12) with no overlap between groups, no need to correct for multiple comparisons, and greater power than the univariate Statistical Parametric Mapping (SPM), multimodal SPM or multivariate PLS analysis of either imaging modality alone. This technique has the potential to link patterns of information among any number of complementary images from an individual, to use other kinds of complementary complex datasets besides brain images, and to characterize individual state-or traitdependent brain patterns in a more powerful way.

No abstract

Slippery liquid-infused porous surfaces (SLIPS) have potential impact on a wide range of industries, including healthcare, food packaging, and automobile. A tremendouseffort has been focused on developing novel fabrication methods for making SLIPS. However, current fabrication methods usually involve harsh conditions and complicated postfabrication modifications or are limited to specific substrates. Presented here is a novel method for the fast and facile fabrication of SLIPS. Layer-by-layer (LBL) assembly of branched polyethylenimine and Nafion, a perfluorinated polyelectrolyte, is performed with methanol as the solvent. Hierarchically rough and superhydrophobic surface is obtained directly without further modification on various substrates. The surface properties are shown to highly depend on the LBL assembly parameters, including deposition cycles, dipping time, rinsing time, and drying time between baths. The polyelectrolyte multilayers obtained with this method are infused with Krytox 100 to form SLIPS surfaces, which show excellent omniphobic, antifouling, self-cleaning, flexible, and optical properties. The result of this study not only simplifies the fabrication of SLIPS surfaces, but also provides great insight for making LBL films with specific morphologies.

The physical properties of ultrahigh molecular weight polyethylene (UHMWPE) are generally highly dependent on its molecular weight. However, in our study, it was found that two UHMWPE samples of similar molecular weight, SLL‐5 and GUR 4150, have significantly different impact strengths, with the Charpy impact strength of GUR 4150 being almost 3.4 times that of SLL‐5. To reveal the reasons, the structure–property relations of these UHMWPE materials were investigated. Morphologies of the nascent particles and impact fracture surfaces, the melting behavior, rheological behavior, and three‐phase (crystalline, amorphous, and interphase) contents were characterized by scanning electron microscopy, differential scanning calorimetry, advanced rotary rheometer, and Raman spectroscopy, respectively. It was observed that no significant differences in the crystal structures of SLL‐5 and GUR 4150, but GUR 4150 had smaller nascent particles sizes and a lower degree of entanglement when compared with those of SLL‐5. Accordingly, a mechanism to clarify the significant difference in the impact strengths of GUR 4150 and SLL‐5 was developed. More importantly, this work may be useful for improving the preparation technologies and industrial applications of UHMWPE. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 632–641

Although it is generally believed that the extraordinarily high molecular weight plays a great role in the excellent wear resistance of ultrahigh-molecular-weight polyethylene (UHMWPE), the mechanism behind this effect remains poorly understood. In this study, we investigated the wear behavior of UHMWPE with respect to its microstructures, measured in terms of its crystallinity, lamellar thickness and crystallite size, entanglement, interphase fractions, and surface roughness. From these structure− property relationships, we conclude that the high wear resistance of UHMWPE can be attributed to its higher degree of entanglement and its high fraction content of interphase domains; the other parameters were either not significant or not relevant. Accordingly, we propose a mechanism in which the more greatly entangled molecular chain networks of UHMWPE protect the surface and subsurface layers from damage under stresses during sliding wear.

In this paper, through generalizing the 2 × 2 matrix Ablowitz–Kaup–Newell–Segur linear eigenvalue problem to the 2N × 2N case, a new Lax pair associated with the multi-component modified Korteweg–de Vries equations is derived in the form of block matrices. Furthermore, the Darboux transformation is applied to this integrable multi-component system, and the n-times iterative potential formula is presented by applying the Darboux transformation successively. This formula enables us to construct a series of explicit solutions of multi-component modified Korteweg–de Vries equations. In illustration, starting from the zero background, we construct the multi-soliton solutions by performing the symbolic computation.