Quasinonlocal coupling of nonlocal diffusions

We developed a new self-adjoint, consistent, and stable coupling strategy for nonlocal diffusion models, inspired by the quasinonlocal atomistic-to-continuum method for crystalline solids. The proposed coupling model is coercive with respect to the energy norms induced by the nonlocal diffusion kernels as well as the $L^2$ norm, and it satisfies the maximum principle. A finite difference approximation is used to discretize the coupled system, which inherits the property from the continuous formulation. Furthermore, we design a numerical example which shows the discrepancy between the fully nonlocal and fully local diffusions, whereas the result of the coupled diffusion agrees with that of the fully nonlocal diffusion.Comment: 28 pages, 3 figures, ams.or

A quasinonlocal coupling method for nonlocal and local diffusion models

In this paper, we extend the idea of "geometric reconstruction" to couple a nonlocal diffusion model directly with the classical local diffusion in one dimensional space. This new coupling framework removes interfacial inconsistency, ensures the flux balance, and satisfies energy conservation as well as the maximum principle, whereas none of existing coupling methods for nonlocal-to-local coupling satisfies all of these properties. We establish the well-posedness and provide the stability analysis of the coupling method. We investigate the difference to the local limiting problem in terms of the nonlocal interaction range. Furthermore, we propose a first order finite difference numerical discretization and perform several numerical tests to confirm the theoretical findings. In particular, we show that the resulting numerical result is free of artifacts near the boundary of the domain where a classical local boundary condition is used, together with a coupled fully nonlocal model in the interior of the domain

Dissolution and Mechanical properties of Bioresorbable Glass Fibres for use in Paediatric tracheal stents

Stents provide biological support in body conduits and are useful for counteracting stenosis (constriction) in cardiovascular, gastrointestinal, uretheral and airway passages1. However, the current widespread use of permanent metal stents that remain throughout the lifespan of a patient, threaten restenosis, thrombosis, or physical irritation if not surgically removed. In infants the clinical requirement is for a stent that retains structural integrity for periods of several weeks up to many months in vivo during host tissue restoration2 and from a materials perspective this requires an implant with appropriate mechanical and degradation characteristics. Bioresorbable phosphate glass fibres have shown enormous potential for temporary implants and tissue repair, owing to their mechanical properties and solubility in aqueous media which can be modified by addition of various oxide compounds3,4. Further, when combined with degradable polymers the resulting glass fibre polymer composites (GFRP) become ductile allowing them to be forged into supporting scaffolds with suitable mechanical and dissolution properties. To date however, their use for stenting applications has not been investigated possibly due to major difficulties of processing these compositions into fibre form. In this study, two phosphate glass fibre compositions containing SiO2 (silica) and B2O3 (Boron) were fabricated to test the hypothesis that B2O3 containing phosphate glass fibres present enhanced mechanical and dissolution behaviour for use as a degradable stent

Waste to treasure: Regeneration of porous Co-based catalysts from spent LiCoO2 cathode materials for efficient oxygen evolution reaction

The increasing demand for portable electronic devices and electric vehicles (EV) has triggered the rapid growth of rechargeable Li-ion batteries (LIBs) markets. However, in the near future, it is predicated a large amount of spent LIBs will be scrapped, imposing huge pressure on environmental protection and resources reclaiming. The effective recycling or regeneration of the spent LIBs not only relieves the environmental burdens but also avoids the waste of valuable metal resources. Herein, a porous Co9S8/Co3O4 heterostructure is successfully synthesized from the spent LiCoO2 (LCO) cathode materials via a conventional hydrometallurgy and sulfidation process. The fabricated Co9S8/Co3O4 catalyst proves high catalytic activity towards oxygen evolution reaction (OER) in alkaline solution, with an overpotential of 274 mV to achieve the current density of 10 mA cm-2 and a Tafel slope of 48.7 mV dec-1. This work demonstrates a facile regeneration process of Co-based electrocatalysts from the spent LiCoO2 cathode materials for efficient oxygen evolution reaction

Microbial diversities (16S and 18S rRNA gene pyrosequencing) and environmental pathogens within drinking water biofilms grown on the common premise plumbing materials unplasticized polyvinylchloride and copper

Drinking water (DW) biofilm communities influence the survival of opportunistic pathogens, yet knowledge about the microbial composition of DW biofilms developed on common in-premise plumbing material is limited. Utilizing 16S and 18S rRNA gene pyrosequencing, this study characterized the microbial community structure within DW biofilms established on unplasticized polyvinyl chloride (uPVC) and copper (Cu) surfaces and the impact of introducing Legionella pneumophila (Lp) and Acanthamoeba polyphaga. Mature (\u3e 1 year old) biofilms were developed before inoculation with sterilized DW (control, Con), Lp, or Lp and A. polyphaga (LpAp). Comparison of uPVC and Cu biofilms indicated significant differences between bacterial (P = 0.001) and eukaryotic (P \u3c 0.01) members attributable to the unique presence of several family taxa: Burkholderiaceae, Characeae, Epistylidae, Goniomonadaceae, Paramoebidae, Plasmodiophoridae, Plectidae, Sphenomonadidae, and Toxariaceae within uPVC biofilms; and Enterobacteriaceae, Erythrobacteraceae, Methylophilaceae, Acanthamoebidae, and Chlamydomonadaceae within Cu biofilms. Introduction of Lp alone or with A. polyphaga had no effect on bacterial community profiles (P \u3e 0.05) but did affect eukaryotic members (uPVC, P \u3c 0.01; Cu, P = 0.001). Thus, established DW biofilms host complex communities that may vary based on substratum matrix and maintain consistent bacterial communities despite introduction of Lp, an environmental pathogen

Mechanism and Function of the Outer Membrane Channel TolC in Multidrug Resistance and Physiology of Enterobacteria

TolC is an archetypal member of the outer membrane efflux protein (OEP) family. These proteins are involved in export of small molecules and toxins across the outer membrane of Gram-negative bacteria. Genomes of some bacteria such as Pseudomonas species contain multiple copies of OEPs. In contrast, enterobacteria contain a single tolC gene, the product of which functions with multiple transporters. Inactivation of tolC has a major impact on enterobacterial physiology and virulence. Recent studies suggest that the role of TolC in physiology of enterobacteria is very broad and affects almost all aspects of cell adaptation to adverse environments. We review the current state of understanding TolC structure and present an integrated view of TolC function in enterobacteria. We propose that seemingly unrelated phenotypes of tolC mutants are linked together by a single most common condition – an oxidative damage to membranes

Towards High-Quality Neural TTS for Low-Resource Languages by Learning Compact Speech Representations

This paper aims to enhance low-resource TTS by reducing training data requirements using compact speech representations. A Multi-Stage Multi-Codebook (MSMC) VQ-GAN is trained to learn the representation, MSMCR, and decode it to waveforms. Subsequently, we train the multi-stage predictor to predict MSMCRs from the text for TTS synthesis. Moreover, we optimize the training strategy by leveraging more audio to learn MSMCRs better for low-resource languages. It selects audio from other languages using speaker similarity metric to augment the training set, and applies transfer learning to improve training quality. In MOS tests, the proposed system significantly outperforms FastSpeech and VITS in standard and low-resource scenarios, showing lower data requirements. The proposed training strategy effectively enhances MSMCRs on waveform reconstruction. It improves TTS performance further, which wins 77% votes in the preference test for the low-resource TTS with only 15 minutes of paired data.Comment: Submitted to ICASSP 202