Study of imbibition in various geometries using phase field method

Phase field method has been widely utilized to study multiphase flow problems, but has seldom been applied to the study of imbibition. Previous methods used to simulate imbibition, such as moving mesh method, need to specify capillary pressure as a boundary condition a priori, whereas phase field method can calculate capillary pressure automatically for various geometries. Therefore, phase field method would be a versatile tool for the study of imbibition in various geometries. In this paper, phase field method is employed to solve dynamical imbibition problem in various geometries, including straight tube, conical tube and structures in which the topology changes. The variation of the imbibition height with respect to time from phase field simulation is verified with theoretical predictions from Lucas-Washburn law in a straight capillary tube with three gravitational scenarios. In addition, the capillary pressure and velocity field are found to be consistent with Laplace-Young equation and Hagen-Poiseuille equation in various geometries. The applicability and accuracy of the phase field method for the study of imbibition in structures with changing topology are also discussed.Cited as: Xiao, J., Luo, Y., Niu, M., Wang, Q., Wu, J., Liu, X., Xu, J. Study of imbibition in various geometries using phase field method. Capillarity, 2019, 2(4): 57-65, doi: 10.26804/capi.2019.04.0

Synaptic Targeting and Function of SAPAPs Mediated by Phosphorylation-Dependent Binding to PSD-95 MAGUKs

The PSD-95/SAPAP/Shank complex functions as the major scaffold in orchestrating the formation and plasticity of the post-synaptic densities (PSDs). We previously demonstrated that the exquisitely specific SAPAP/Shank interaction is critical for Shank synaptic targeting and Shank-mediated synaptogenesis. Here, we show that the PSD-95/SAPAP interaction, SAPAP synaptic targeting, and SAPAP-mediated synaptogenesis require phosphorylation of the N-terminal repeat sequences of SAPAPs. The atomic structure of the PSD-95 guanylate kinase (GK) in complex with a phosphor-SAPAP repeat peptide, together with biochemical studies, reveals the molecular mechanism underlying the phosphorylation-dependent PSD-95/SAPAP interaction, and it also provides an explanation of a PSD-95 mutation found in patients with intellectual disabilities. Guided by the structural data, we developed potent non-phosphorylated GK inhibitory peptides capable of blocking the PSD-95/SAPAP interaction and interfering with PSD-95/SAPAP-mediated synaptic maturation and strength. These peptides are genetically encodable for investigating the functions of the PSD-95/SAPAP interaction in vivo. Using structural biology, cell biology, and electrophysiology approaches, Zhu et al. demonstrate that phosphorylation of the N-terminal repeating sequences of SAPAPs is required for the SAPAP/PSD-95 complex formation and SAPAP's synaptic targeting and maturation functions. They also developed a potent non-phosphorylated PSD-95 GK inhibitory peptide that can effectively disrupt the SAPAP/PSD-95 complex formation and thus inhibit excitatory synaptic activities. Keywords: GK domain; PSD-95; SAPAP; MAGUK; postsynaptic density; synaptic scaffold proteins; synaptogenesis; synaptic plasticit

Synthesis and characterization of ceramic composites and coatings by sol-gel and chemical vapor infiltration processes

This research is devoted to the development of a new method for the synthesis of nitrides by thermal nitridation of metal oxides or hydroxides in gaseous mixtures of ammonia and methane. Thermodynamic analysis was conducted for metal oxide-CH\sb4-NH\sb3 systems. Based on theoretical predictions, metal nitrides such as AlN, TiN, and their composites Al\sb2O\sb3 + TiN and AlN+ SiC were prepared experimentally. Crystalline AlN and TiN were obtained by this method. Temperature and time effects were studied. The lowest reaction temperatures for TiN and AlN were 750\sp\circC and 950\sp\circC, respectively. The particle sizes of the powders were studied using SEM and XRD. Properties such as electrical and oxidation resistance of the powder composites were investigated. Those properties vary with the compositions of the composites. The electrical resistances change from a good conducting material to a good insulator by increasing the Al\sb2O\sb3 or AlN content in their composites.^ Another major part of this research involves thin film coating on various substrates such as fibers, metal substrates, and silicon wafers. Alumina coatings on a silicon carbide monofilament, BP-SIGMA, a SiC coated boron monofilament, SICABO, and on SiC yarns Nicalon, and carbon Nicalon (C-Nicalon) were produced by a sol-gel process. The coated BP and SICABO fibers retained the strengths of the as-received fibers even after the coated fibers were heated to 1000\sp\circC in air for 24 hours. The strengths of the as-received C-Nicalon fibers were also maintained after the coated fiber were heated to 1000\sp\circC in air. However, the coated Nicalon fibers were totally degraded after the coated fibers were heated in air at 1000\sp\circC. The degradation mechanism was investigated using Auger depth profiles. The carbon layer proved to be very important in preventing Al and O diffusion into the coated fibers during heat treatment. Evenness and thicknesses of the coating layers were studied by scanning electron microscopy (SEM) which showed that uniform and nonbridging coatings could be obtained if the coating, drying and heating processes were carefully controlled.

Multifractal Structure of the Divergence Points of Some Homogeneous Moran Measures

The point x for which the limit limr→0⁡(log⁡μBx,r/log⁡r) does not exist is called divergence point. Recently, multifractal structure of the divergence points of self-similar measures has been investigated by many authors. This paper is devoted to the study of some Moran measures with the support on the homogeneous Moran fractals associated with the sequences of which the frequency of the letter exists; the Moran measures associated with this kind of structure are neither Gibbs nor self-similar and than complex. Such measures possess singular features because of the existence of so-called divergence points. By the box-counting principle, we analyze multifractal structure of the divergence points of some homogeneous Moran measures and show that the Hausdorff dimension of the set of divergence points is the same as the dimension of the whole Moran set

Azimuth Ambiguity Suppression in SAR Images Based on Compressive Sensing Recovery Algorithm

Azimuth ambiguities appear widely throughout spaceborne Synthetic Aperture Radar (SAR) images. If the ambiguous energy is relatively strong, a large number of brilliant areas or points will emerge, which may be erroneously judged as actual targets. This is a disadvantage in image interpretation. Due to the fact that ambiguous energy is mixed with energy from the main zone in the frequency and time domains, it is difficult to suppress azimuth ambiguity to a reasonable level using the existing approach without loss of resolution. This study proposes an innovative approach for suppressing azimuth ambiguity based on the compressive sensing recovery framework, in which the original image acts as prior information and the corresponding frequency spectrum truncated in a proper ratio acts as measurement information. With the proposed approach, highresolution low-ambiguity images can be obtained by iteration. We used simulation and satellite data to validate the effectiveness of this proposed approach in suppressing azimuth ambiguity

Trait Depression and Subjective Well-Being: The Chain Mediating Role of Community Feeling and Self-Compassion

Although subjective well-being has been widely discussed as being one of the important indicators of clinical depression, few studies have explored how it relates to trait depression. In particular, increasing the number of positive experiences has long been a potential goal for depression-related clinical interventions, but the mechanisms by which such interventions work in countering depression have been poorly studied. Grounded in the cognitive theory of depression, the current study aimed to address this specific gap by testing the mediating effects of community feeling and self-compassion between trait depression and subjective well-being. A survey of 783 college students found that trait depression was not only able to directly and negatively predict individual subjective well-being but also indirectly predict individual subjective well-being through the mediating role of community feeling and self-compassion alone and through the chain mediating role of self-compassion from community feeling. These findings reveal the internal mechanisms of trait depression that, to some extent, impede subjective well-being and offer certain guiding significance for the self-regulation of interventions for clinical and non-clinical individuals with trait depression

Collaborative Representation based Face Classification Exploiting Block Weighted LBP and Analysis Dictionary Learning

Traditional collaborative representation based classification (CRC) method usually faces the challenge of data uncertainty hence results in poor performance, especially in the presence of appearance variations in pose, expression and illumination. To overcome this issue, this paper presents a CRC-based face classification method by jointly using block weighted LBP and analysis dictionary learning. To this end, we first design a block weighted LBP histogram algorithm to form a set of local histogram-based feature vectors instead of using raw images. By this means we are able to effectively decrease data redundancy and uncertainty derived from image noises and appearance variations. Second, we adopt an analysis dictionary learning model as the projection transform to construct an analysis subspace, in which a new sample is characterized with the improved sparsity of its reconstruction coefficient vector. The crucial role of the analysis dictionary learning method in CRC is revealed by its capacity of the collaborative representation in an analytic coefficient space. Extensive experimental results conducted on a set of well-known face databases demonstrate the merits of the proposed method

Histological patterns and associated PSA levels for prostatic adenocarcinoma following brachytherapy.

Changes in morphologic patterns over a time course following radiation and their corresponding PSA levels were investigated. A total of 60 patients with prostatic adenocarcinoma treated with brachytherapy between 1993 and 2003, who had at least one positive post-radiation biopsy, were evaluated for their morphologic patterns as well as the associated PSA levels. A total of 86 positive post-radiation biopsies were performed. There were 17 patients with more than 1 positive post-radiation biopsy and 43 patients with single positive biopsy. Among the 17 with more than 1 positive biopsy, the morphologic patterns of treatment effect were commonly followed by patterns without treatment effect on subsequent biopsies. The morphology without treatment effect followed by treatment effect was infrequent. Furthermore, over a time course, the later the positive post-radiation biopsy, the much more common the morphologic pattern without treatment effect was observed. Compared to the morphologic pattern with treatment effect, the morphology without treatment effect was associated with a significantly higher PSA level (mean 0.69 versus 2.78 ng/ml,