A 2.5-Dimensional biomimetic dual-functional bifacial-evaporator for high efficient evaporation and water purification.

Nowadays, solar-driven interfacial steam generation (SISG) is a sustainable and green technology for mitigating the water shortage crisis. Nevertheless, SISG is suffering from the enrichment of volatile organic compounds in condensate water and non-volatile organic compounds in feed water in practical applications. Herein, taking inspiration from nature, a dual-functional bifacial-CuCoNi (Bi-CuCoNi) evaporator with a special biomimetic urchin-like microstructure was successfully prepared. The unique design with 2.5-Dimensional bifacial working sides and urchin-like light absorption microstructure provided the Bi-CuCoNi evaporator with remarkable evaporation performance (1.91 kg m-2 h-1 under 1 kW m-2). Significantly, due to the urchin-like microstructure, the adequately exposed catalytic active sites enabled the Bi-CuCoNi/peroxydisulfate (PDS) system to degrade non-volatile organic pollutants (removal rate of 99.3 % in feed water, close to 100 % in condensate water) and the volatile organic pollutants (removal rate of 99.1 % in feed water, 98.2 % in condensate water) simultaneously. Moreover, the Bi-CuCoNi evaporator achieved non-radical pathway degradation at whole-stages. The dual-functional evaporator successfully integrated advanced oxidation processes (AOPs) into SISG, providing a new idea for high-quality freshwater production from polluted wastewater. ENVIRONMENTAL IMPLICATION: Inspired by nature, a dual-functional bifacial CuCoNi evaporator with a special biomimetic urchin-like microstructure formed by CuCoNi oxide nanowires grown on nickel foam by the hydrothermal synthesis method was successfully prepared. The prepared Bi-CuCoNi evaporator can effectively degrade organic pollutants in feed water and condensate water simultaneously during SISG, thus generating high-quality fresh water. Meanwhile, the health risks associated with the accumulation of organic pollutants in water during traditional SISG were reduced via green and sustainable way. The spatial 2.5-Dimensional structural design of Bi-CuCoNi provided new insights for achieving efficient water evaporation and fresh water generation from various polluted wastewater.

Bifunctional Solar Evaporator with Co/N-Doped Graphene Oxide for Synergistic Steam Generation and Organic Pollutant Degradation.

Solar-driven interfacial steam generation (SISG) is a promising technology for alleviating freshwater shortage. However, when the SISG technology is applied to wastewater treatment, the contaminant would be enriched in residual bulk water. Herein, a dual-functional evaporator was constructed via tactfully decorating Co/N-doped graphene oxide (GO) on melamine foam (MF), which can simultaneously achieve efficient vapor production and source water purification. N-doped carbon nanotubes (NCNTs) endowed evaporators with powerful light absorption and water transport performance, guaranteeing an evaporation rate of 2.02 kg m-2 h-1 under 1 sun irradiation. Meanwhile, the catalytic activity of the carbon layer was adjusted by the N dopant and embedded Co particles, providing abundant active sites to activate peroxymonosulfate (PMS). When treating the solution containing sulfamethoxazole (SMX), no SMX residues were detected in the remaining bulk water (up to 100% SMX degradation efficiency within 60 min), demonstrating that reactive oxygen species (ROS) were generated to attack SMX in the source water. The bifunctional evaporator successfully combined SISG and advanced oxidation processes (AOPs), providing an ingenious strategy for solving the problem of wastewater enrichment during SISG.

A dual-functional hydrogel for efficient water purification: Integrating solar interfacial evaporation with fenton reaction.

Solar interfacial evaporation is a potential technology to produce clean water due to its simplicity and being driven by renewable clean energy, but it still requires further development to break through the bottleneck of removing volatile organic compounds (VOCs), especially in wastewater treatment. Herein, we proposed a dual-functional hydrogel evaporator that coupled solar interfacial evaporation with Fenton reaction to simultaneously remove VOCs and non-volatile pollutants from water with low energy consumption and high efficiency. The evaporator was composed with ß-FeOOH and polydopamine (PDA) on an electrospun nanofibrous hydrogel. Arising from the PDA with excellent photothermal properties, the evaporator revealed a high light absorption characteristics (∼90%) and photothermal efficiency (83.4%), which ensured a favorable evaporation rate of 1.70 kg m-2 h-1 under one solar irradiation. More importantly, benefited from the coupled Fenton reaction, the VOCs removal rate of ß-FeOOH@PDA/polyvinyl alcohol nanofibrous hydrogel (ß-FeOOH@PPNH) reached 95.8%, which was 6.5 times than that of sole solar interfacial evaporation (14.8%). In addition, the evaporator exhibited an outstanding non-volatile pollutant removal capability and stable removal performance for organic pollutants over a long period of operation. The prepared ß-FeOOH@PPNH evaporator provides a promising idea for simultaneous removal of non-volatile pollutants and volatile pollutants performance in long-term water purification.

Boosting peroxymonosulfate activation by iron-based dual active site for efficient sulfamethoxazole degradation: synergism of Fe and N-doped carbon.

Persulfate activation is emerged as an alternative applied in environment remediation, but it is still a great challenge to develop highly active catalysts for efficient degradation of organic pollutants. Herein, a heterogeneous iron-based catalyst with dual-active sites was synthesized by embedding Fe nanoparticles (FeNPs) onto the nitrogen-doped carbon, which was used to activate peroxymonosulfate (PMS) for antibiotics decomposition. The systematic investigation indicated the optimal catalyst exhibited a significant and stable degradation efficiency of sulfamethoxazole (SMX), in which the SMX can be completely removed in 30 min even after 5 cycle tests. Such satisfactory performance was mainly attributed to the successful construction of electron-deficient C centers and electron-rich Fe centers via the short C-Fe bonds. These short C-Fe bonds accelerated electrons to shuttle from SMX molecules to electron-rich Fe centers with a low transmission resistance and short transmission distance, enabling Fe (III) to receive electrons to promote the regeneration of Fe (II) for durable and efficient PMS activation during SMX degradation. Meanwhile, the N-doped defects in the carbon also provided reactive bridges that accelerated the electron transfer between FeNPs and PMS, ensuring the synergistic effects toward Fe (II)/Fe (III) cycle to some extent. The quenching tests and electron paramagnetic resonance (EPR) indicated O2·- and 1O2 were the dominant active species during the SMX decomposition. As a result, this work provides an innovative method to construct a high-performance catalyst to active sulfate for organic contaminant degradation.

A novel, flexible porous nanofibrous hydrogel interfacial solar evaporator for highly efficient seawater and wastewater purification.

Solar desalination is recognized as one of the eco-friendly and sustainable ways to alleviate the global freshwater crisis but still requires further research, especially in developing high-performance evaporators. Herein, we prepared an efficient carbon nanotubes (CNTs)@polyvinyl alcohol (PVA) nanofibrous hydrogel evaporator by electrospinning and subsequently chemical cross-linking treatment. Due to CNTs with good light absorption capacity, the evaporator exhibited an excellent light absorption capacity (>90%) throughout the full spectrum range (250-2500 nm). Meanwhile, the interconnected pores from electrospinning, as well as the intermediate water in the hydrogel, ensured the prepared evaporator with a favorable evaporation rate of up to 2.16 kg m-2 h-1 and photothermal conversion efficiency of ∼88.13% under one solar light intensity. For long-term seawater desalination, the CNTs@PVA nanofibrous hydrogel evaporator also presented superior salt resistance, durability and good self-cleaning properties. Besides, various non-volatile pollutants can be completely removed by the prepared evaporator during the wastewater purification. As a result, this work is considered to provide a new direction for developing high-performance evaporators to provide freshwater through seawater desalination and wastewater purification.

UNOC: Understanding Occlusion for Embodied Presence in Virtual Reality.

Tracking body and hand motions in 3D space is essential for social and self-presence in augmented and virtual environments. Unlike the popular 3D pose estimation setting, the problem is often formulated as egocentric tracking based on embodied perception (e.g., egocentric cameras, handheld sensors). In this article, we propose a new data-driven framework for egocentric body tracking, targeting challenges of omnipresent occlusions in optimization-based methods (e.g., inverse kinematics solvers). We first collect a large-scale motion capture dataset with both body and finger motions using optical markers and inertial sensors. This dataset focuses on social scenarios and captures ground truth poses under self-occlusions and body-hand interactions. We then simulate the occlusion patterns in head-mounted camera views on the captured ground truth using a ray casting algorithm and learn a deep neural network to infer the occluded body parts. Our experiments show that our method is able to generate high-fidelity embodied poses by applying the proposed method to the task of real-time egocentric body tracking, finger motion synthesis, and 3-point inverse kinematics.

Monocular 3D Pose Estimation via Pose Grammar and Data Augmentation.

In this paper, we propose a pose grammar to tackle the problem of 3D human pose estimation from a monocular RGB image. Our model takes estimated 2D pose as the input and learns a generalized 2D-3D mapping function to leverage into 3D pose. The proposed model consists of a base network which efficiently captures pose-aligned features and a hierarchy of Bi-directional RNNs (BRNNs) on the top to explicitly incorporate a set of knowledge regarding human body configuration (i.e., kinematics, symmetry, motor coordination). The proposed model thus enforces high-level constraints over human poses. In learning, we develop a data augmentation algorithm to further improve model robustness against appearance variations and cross-view generalization ability. We validate our method on public 3D human pose benchmarks and propose a new evaluation protocol working on cross-view setting to verify the generalization capability of different methods. We empirically observe that most state-of-the-art methods encounter difficulty under such setting while our method can well handle such challenges.

Insights into the impact of polydopamine modification on permeability and anti-fouling performance of forward osmosis membrane.

Forward osmosis (FO) has drawn wide attention as a promising method to address world-wide water crisis due to the advantages of low-energy consumption and easy separation operation. Unfortunately, the trade-off between permeability and selectivity as well as membrane fouling hindered the application of forward osmosis. Surface modification is a feasible method to address these issues. However, there is a lack of systematic evaluation about the effect of modification position on FO performance due to the asymmetric structure of thin film composite (TFC) FO membrane. To provide new insights into the design of FO membrane with satisfied permeability and fouling resistance, novel TFC FO membranes were fabricated by introducing polydopamine (PDA) on the support layer (TFC-I) or active layer (TFC-S), respectively. The surface morphology, chemical composition and wettability of the fabricated membrane were studied. It was found that the surface wettability of the modified membrane was improved greatly compared to pristine TFC membrane (TFC-C). Moreover, TFC-S membrane displayed a rougher surface than that of TFC-I membrane. As a result, a superior TFC-S membrane with a water flux of 60.95 ± 3.15 L m-2h-1 in AL-DS mode was obtained, which was 72.61% and 17.87% higher than that of TFC-C and TFC-I membrane, respectively. In addition, the TFC-S membrane also presented an excellent fouling resistance and membrane regeneration performance during the three organic fouling cycle experiments. The results indicated that the introduction of PDA as a surface coating for TFC membranes modification guaranteed the high-performance and fouling resistance. Especially, the PDA coating on the support layer surface resulted in an enhancement in permeability, while both the permeability and anti-fouling performance were significantly improved with the PDA coating on the polyamide active layer surface. This study provides new insights into the development of modification TFC-FO membranes for practical applications in water treatment.

Complex background subtraction by pursuing dynamic spatio-temporal models.

Although it has been widely discussed in video surveillance, background subtraction is still an open problem in the context of complex scenarios, e.g., dynamic backgrounds, illumination variations, and indistinct foreground objects. To address these challenges, we propose an effective background subtraction method by learning and maintaining an array of dynamic texture models within the spatio-temporal representations. At any location of the scene, we extract a sequence of regular video bricks, i.e., video volumes spanning over both spatial and temporal domain. The background modeling is thus posed as pursuing subspaces within the video bricks while adapting the scene variations. For each sequence of video bricks, we pursue the subspace by employing the auto regressive moving average model that jointly characterizes the appearance consistency and temporal coherence of the observations. During online processing, we incrementally update the subspaces to cope with disturbances from foreground objects and scene changes. In the experiments, we validate the proposed method in several complex scenarios, and show superior performances over other state-of-the-art approaches of background subtraction. The empirical studies of parameter setting and component analysis are presented as well.