Conditional Positional Encodings for Vision Transformers

We propose a conditional positional encoding (CPE) scheme for vision Transformers. Unlike previous fixed or learnable positional encodings, which are pre-defined and independent of input tokens, CPE is dynamically generated and conditioned on the local neighborhood of the input tokens. As a result, CPE can easily generalize to the input sequences that are longer than what the model has ever seen during training. Besides, CPE can keep the desired translation-invariance in the image classification task, resulting in improved classification accuracy. CPE can be effortlessly implemented with a simple Position Encoding Generator (PEG), and it can be seamlessly incorporated into the current Transformer framework. Built on PEG, we present Conditional Position encoding Vision Transformer (CPVT). We demonstrate that CPVT has visually similar attention maps compared to those with learned positional encodings. Benefit from the conditional positional encoding scheme, we obtain state-of-the-art results on the ImageNet classification task compared with vision Transformers to date. Our code will be made available at https://github.com/Meituan-AutoML/CPVT .Comment: A general purpose conditional position encoding for vision transformer

A magnetic γ-Fe\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e3\u3c/sub\u3e@PANI@TiO\u3csub\u3e2\u3c/sub\u3e core–shell nanocomposite for arsenic removal \u3ci\u3evia\u3c/i\u3e a coupled visible-light-induced photocatalytic oxidation– adsorption process†

Arsenic polluted groundwater impairs human health and poses severe threats to drinking water supplies and ecosystems. Hence, an efficient method of simultaneous oxidation of As(III) to As(V), and removal of As(V) from water has triggered increasing attention. In this study, a magnetic γ-Fe2O3 core–shell heterojunction nanocomposite was synthesized by means of hydrothermal crystallization of TiO2 on the surface of the magnetic core–shell loaded with polyaniline (γ-Fe2O3@PANI@TiO2). As an efficient photocatalyst coupled with adsorption, γ-Fe2O3@PANI@TiO2 has a high light utilization and good adsorption capacity. Notably, the nanocomposite has excellent stability at various initial pH values with good reusability. Among the co-existing ions investigated, PO43- has the greatest competitive reaction. The photocatalytic oxidation of As(III) on γ-Fe2O3@PANI@TiO2 is dominated by the synergy of several active substances, with superoxide free radicals and photogenerated holes being the major players

Towards Better Entity Linking with Multi-View Enhanced Distillation

Dense retrieval is widely used for entity linking to retrieve entities from large-scale knowledge bases. Mainstream techniques are based on a dual-encoder framework, which encodes mentions and entities independently and calculates their relevances via rough interaction metrics, resulting in difficulty in explicitly modeling multiple mention-relevant parts within entities to match divergent mentions. Aiming at learning entity representations that can match divergent mentions, this paper proposes a Multi-View Enhanced Distillation (MVD) framework, which can effectively transfer knowledge of multiple fine-grained and mention-relevant parts within entities from cross-encoders to dual-encoders. Each entity is split into multiple views to avoid irrelevant information being over-squashed into the mention-relevant view. We further design cross-alignment and self-alignment mechanisms for this framework to facilitate fine-grained knowledge distillation from the teacher model to the student model. Meanwhile, we reserve a global-view that embeds the entity as a whole to prevent dispersal of uniform information. Experiments show our method achieves state-of-the-art performance on several entity linking benchmarks.Comment: Accepted by ACL 2023 Main Conferenc

Evidence-Based Study to Compare Daodi

Background. Daodi medicinal material is widely used in Chinese herb medication. However, there is a lack of systematic methodology for identifying characteristics associated with good quality and reliable efficacy of Daodi med-material. Purpose. The purpose of this study is to provide some evidence to further substantiate the use of Daodi medicinal materials. Methods. Seven relevant databases were searched before July 2014. Two evaluators were responsible for screening and categorizing the results. The data was analyzed with Microsoft Excel 2007 and SPSS 21.0 statistical software. Results. Overall, 107 articles were systematically analyzed. Of these studies, 55.1% (59/107) focused on the methodology to assess Daodi med-material, and 38.3% (41/107) were interested in med-material ingredients, soil physical and chemical properties, and the geological background system (GBS). Only 6.5% (7/107) of studies were mainly conducted as clinical trials and animal experiments. Conclusion. Comparisons between Daodi and non-Daodi materials have been studied mainly in terms of the ingredients or composition of medical materials, soil physics and chemistry, and the GBS, and some identifying methodologies have been created to identify Daodi attributes. Until now, there is still no consensus of comparison criteria between Daodi and non-Daodi medicinal material. Only a few studies were conducted through animal experiments and clinical trials to determine Daodi superiority

Phase transfer-based high-efficiency recycling of precious metal electrocatalysts

Recycling precious metals with high-efficiency is undoubtedly beneficial to optimize resource utilization for environmental remediation and sustainable development. Herein, we report an efficient route to recycle the palladium (Pd) and platinum (Pt) electrocatalysts using a phase transfer method. This strategy involves acidic dissolution of deactivated precious metal (Pd/Pt) electrocatalysts from their loading substrates, mixing with an ethanolic solution of dodecylamine (DDA), subsequent extraction of metal ions into a non-polar organic phase, and final reduction by sodium borohydride to reproduce high-performance electrocatalysts towards typical electrochemical reactions, e.g., oxygen reduction reaction (ORR) and ethanol oxidation reaction (EOR). In specific, the transfer efficiencies are up to 98% and the final recovery rate is over 85% for Pd and Pt electrocatalysts in each cycle. This approach symbolizes a facile and efficient way to recover precious metals, which might be applied to recycling a wide range of metals in various realms after appropriate modifications

A Platinum Monolayer Core-Shell Catalyst with a Ternary Alloy Nanoparticle Core and Enhanced Stability for the Oxygen Reduction Reaction

We synthesize a platinum monolayer core-shell catalyst with a ternary alloy nanoparticle core of Pd, Ir, and Ni. A Pt monolayer is deposited on carbon-supported PdIrNi nanoparticles using an underpotential deposition method, in which a copper monolayer is applied to the ternary nanoparticles; this is followed by the galvanic displacement of Cu with Pt to generate a Pt monolayer on the surface of the core. The core-shell Pd1Ir1Ni2@Pt/C catalyst exhibits excellent oxygen reduction reaction activity, yielding a mass activity significantly higher than that of Pt monolayer catalysts containing PdIr or PdNi nanoparticles as cores and four times higher than that of a commercial Pt/C electrocatalyst. In 0.1 M HClO4, the half-wave potential reaches 0.91 V, about 30 mV higher than that of Pt/C. We verify the structure and composition of the carbon-supported PdIrNi nanoparticles using X-ray powder diffraction, X-ray photoelectron spectroscopy, thermogravimetry, transmission electron microscopy, and energy dispersive X-ray spectrometry, and we perform a stability test that confirms the excellent stability of our core-shell catalyst. We suggest that the porous structure resulting from the dissolution of Ni in the alloy nanoparticles may be the main reason for the catalyst’s enhanced performance

Three dimensional titanium molybdenum nitride nanowire assemblies as highly efficient and durable platinum support for methanol oxidation reaction

To achieve the practical application of direct methanol fuel cells, the development of highly efficient and durable electrocatalyst for methanol oxidation reaction is urgently needed. Herein, an effective approach is developed to fabricate three dimensional porous titanium nitride with an urchin-like structure, which are composed of numerous interactive nanowire assemblies. When being used as the platinum support, the resulting electrocatalyst delivers a mass activity and specific activity that are both around 4.3 times greater with respect to Pt/C catalyst. Moreover, the activity stability and structural durability of the novel catalyst are also confirmed by comprehensive experimental analysis. This study provides a new way for improving the performance of methanol oxidation reaction by combining the advantages of three dimensional structure, inherent electrochemical durability and strong metal support interaction. (C) 2018 Elsevier Ltd. All rights reserved