Patterning two-dimensional free-standing surfaces with mesoporous conducting polymers

The ability to pattern functional moieties with well-defined architectures is highly important in material science, nanotechnology and bioengineering. Although two-dimensional surfaces can serve as attractive platforms, direct patterning them in solution with regular arrays remains a major challenge. Here we develop a versatile route to pattern two-dimensional free-standing surfaces in a controlled manner assisted by monomicelle close-packing assembly of block copolymers, which is unambiguously revealed by direct visual observation. This strategy allows for bottom-up patterning of polypyrrole and polyaniline with adjustable mesopores on various functional free-standing surfaces, including two-dimensional graphene, molybdenum sulfide, titania nanosheets and even on one-dimensional carbon nanotubes. As exemplified by graphene oxide-based mesoporous polypyrrole nanosheets, the unique sandwich structure with adjustable pore sizes (5-20 nm) and thickness (35-45 nm) as well as enlarged specific surface area (85 m(2) g(-1)) provides excellent specific capacitance and rate performance for supercapacitors. Therefore, this approach will shed light on developing solution-based soft patterning of given interfaces towards bespoke functions

Surfactant-stabilized copper paticles for low-temperature sintering: Paste preparation using a milling with small zirconia beads : Effect of pre-treatment with the disperse medium

Copper paste is considered as a promising candidate for printed electronics in replacement for silver paste. This is owing to copper which has anti-electromigration property, lower cost, and similar conductivity and compared with silver. We synthesize a copper nanoparticle (NP) paste that can be sintered at low temperature for high conductivity. The copper NP paste composes of 50 wt% copper NPs and dipropylene glycol (DPG) as the disperse medium. The effect of DPG coating and various conditions of milling with small beads on improving the dispersity of copper NPs has been investigated. The optimum conditions for milling are at 1000 and 2000 rpm for 30 min. This results in a volume resistivity of 6.62 x 10(-6) Omega.cm after sintering the copper NP paste at 200 degrees C. (C) 2020 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved

Multi-Stream Convolution-Recurrent Neural Networks Based on Attention Mechanism Fusion for Speech Emotion Recognition

The quality of feature extraction plays a significant role in the performance of speech emotion recognition. In order to extract discriminative, affect-salient features from speech signals and then improve the performance of speech emotion recognition, in this paper, a multi-stream convolution-recurrent neural network based on attention mechanism (MSCRNN-A) is proposed. Firstly, a multi-stream sub-branches full convolution network (MSFCN) based on AlexNet is presented to limit the loss of emotional information. In MSFCN, sub-branches are added behind each pooling layer to retain the features of different resolutions, different features from which are fused by adding. Secondly, the MSFCN and Bi-LSTM network are combined to form a hybrid network to extract speech emotion features for the purpose of supplying the temporal structure information of emotional features. Finally, a feature fusion model based on a multi-head attention mechanism is developed to achieve the best fusion features. The proposed method uses an attention mechanism to calculate the contribution degree of different network features, and thereafter realizes the adaptive fusion of different network features by weighting different network features. Aiming to restrain the gradient divergence of the network, different network features and fusion features are connected through shortcut connection to obtain fusion features for recognition. The experimental results on three conventional SER corpora, CASIA, EMODB, and SAVEE, show that our proposed method significantly improves the network recognition performance, with a recognition rate superior to most of the existing state-of-the-art methods

Cognitive Functioning and Nail Salon Occupational Exposure among Vietnamese Immigrant Women in Northern California.

Introduction: Vietnamese nail salon technicians are continuously exposed to neurotoxins linked to cognitive impairments and Alzheimer's disease. This study examined the association of occupational exposure with cognitive function and depressive symptoms among Vietnamese nail salon technicians. Methods: The sample included 155 current or former Vietnamese female nail technicians and 145 control group participants. Measures included the Montreal Cognitive Assessment (MoCA) and the Center for Epidemiologic Studies Depression Scale (CES-D). Results: Average cognitive functioning was significantly higher for the control compared to the nail technician group (mean difference = 1.2, p < 0.05). No differences were observed for depression. Multivariate findings revealed that exposure was negatively associated with cognitive functioning (β = -0.29, 95% CI: -0.53, -0.05, p < 0.05). Discussion: Nail salon work and the extent of occupational exposure were associated with lower cognitive functioning among Vietnamese nail technicians. Longitudinal research can further examine the risk for cognitive decline and dementia for this vulnerable population

Universal and switchable omni-repellency of liquid-infused surfaces for on-demand separation of multiphase liquid mixtures

Mixtures of immiscible liquids are commonly found in the scenarios of environmental protection and many industrial applications. Compared to widely explored water-oil mixtures, small differences in the surface energy of organic liquids, especially for those in multiphase mixtures, make their separation a formidable challenge. Here, a family of versatile coatings based on the reactions between plant polyphenols and 3-aminopropyl triethoxysilane is introduced to regulate the wetting behavior of substrates by forming stable liquid-infused interfaces. The key finding is that when a coated substrate is prewetted with a liquid forming a stable liquid-infused interface, it becomes repellent to any other immiscible liquids. This phenomenon is independent of the surface energy of the initial wetting liquid. This exclusive wetting behavior can lead to distinctive repellency toward almost any liquid by the infusion of an immiscible liquid, even if the difference of surface energy and dielectric constant of a liquid pair is as small as 2.0 mJ m-2 and 1.8, respectively, resulting in universal and switchable omni-repellency. Of particular importance is that the as-prepared coating makes possible the on-demand separation of multiphase liquid mixtures by both continuous membrane filtration and static absorption, presenting a green and cost-effective approach to addressing this major environmental and industrial challenge

Glycosylated copper sulfide nanocrystals for targeted photokilling of bacteria in the near‐infrared II window

Photothermal and photodynamic therapies are established as alternative approaches to combating bacterial infections; however, the heat and reactive oxygen species generated by the photoagents act on both normal and bacterial cells. A targeting strategy is thus required to minimize side effects and enhance the antibacterial efficiency. Glycoconjugates specifically interacting with bacterial lectins have emerged as a new class of materials for targeting bacteria. In this paper, galactosylated plasmonic copper sulfide nanocrystals (Cu2−xS NCs) are used to target Pseudomonas aeruginosa via galactose–LecA interactions and kill the bacteria by simultaneous photothermal and photodynamic therapy. Galactosylated Cu2−xS NCs are obtained by functionalizing the nanocrystals with tri‐thiogalactoside glycoclusters. The excellent specificity of galactosylated nanoparticles toward LecA with a LecA‐deficient P. aeruginosa strain as the control is first demonstrated. Afterward, a laser in the near‐infrared II window is used to kill the bacteria, and the critical role of targeted binding in efficient killing of bacteria is highlighted. This approach can be readily generalized to the targeting of other pathogens which have highly specific carbohydrate‐binding lectins.MOE (Min. of Education, S’pore)MOH (Min. of Health, S’pore)Accepted versio

Polydopamine‐Mediated Superlyophobic Polysiloxane Coating of Porous Substrates for Efficient Separation of Immiscible Liquids

Lyophobic membrane has the potential to separate immiscible liquids. However, the multistep fabrication and limited option of materials have created major challenges for their practical application. Here, a strategy to fabricate superlyophobic materials is presented by using polydopamine (PDA) as an intermediate coating. The results demonstrate that PDA nanoparticles deposited on diverse substrates can direct the subsequent formation of polysiloxane microsheets (PSMSs), which increases surface roughness and results in superlyophobicity towards high surface tension (ST) liquids and superlyophilicity to liquids with ST of 33 mN m-1 and below. Superlyophobic membranes fabricated from stainless steel mesh, cotton fabric, and filter papers show high efficiency for continuous separations of chloroform/water (>96%) and carbon tetrachloride/formamide (>97%). In addition, superlyophobic melamine foam and polyurethane foam can absorb various low ST liquids with capacities ranging from 53 to 120 g g-1 and from 26.5 to 52.5 g g-1, respectively, revealing the efficient separation of a broad range of immiscible liquids. All of the as-prepared superlyophobic materials show excellent regeneration with insignificant change of separation efficiency over 10 cycles. The preparation route for superlyophobic materials in this work introduces a new strategy for the separation of immiscible liquids by both batch absorption and continuous filtration treatment.Nanyang Technological UniversityThis work was supported by College of Engineering at Nanyang Technological University