Showing papers by "Dalian University of Technology published in 2015"

Robust self-cleaning surfaces that function when exposed to either air or oil

Abstract: Superhydrophobic self-cleaning surfaces are based on the surface micro/nanomorphologies; however, such surfaces are mechanically weak and stop functioning when exposed to oil. We have created an ethanolic suspension of perfluorosilane-coated titanium dioxide nanoparticles that forms a paint that can be sprayed, dipped, or extruded onto both hard and soft materials to create a self-cleaning surface that functions even upon emersion in oil. Commercial adhesives were used to bond the paint to various substrates and promote robustness. These surfaces maintained their water repellency after finger-wipe, knife-scratch, and even 40 abrasion cycles with sandpaper. The formulations developed can be used on clothes, paper, glass, and steel for a myriad of self-cleaning applications.

CO2 Hydrogenation to Formate and Methanol as an Alternative to Photo- and Electrochemical CO2 Reduction

Abstract: Photoand Electrochemical CO2 Reduction Wan-Hui Wang,*,† Yuichiro Himeda,*,‡,§ James T. Muckerman, Gerald F. Manbeck, and Etsuko Fujita* †School of Petroleum and Chemical Engineering, Dalian University of Technology, Panjin 124221, China ‡National Institute of Advanced Industrial Science and Technology, Tsukuba Central 5-1, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan JST, ACT-C, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973-5000, United States

Flexible MXene/Carbon Nanotube Composite Paper with High Volumetric Capacitance

Abstract: Dr. M.-Q. Zhao, C. E. Ren, Z. Ling, M. R. Lukatskaya, C. F. Zhang, K. L. Van Aken, Prof. M. W. Barsoum, Prof. Y. Gogotsi Department of Materials Science and Engineering and A. J. Drexel Nanomaterials Institute Drexel University 3141 Chestnut Street , Philadelphia , PA 19104 , USA E-mail: gogotsi@drexel.edu Z. Ling Carbon Research Laboratory Liaoning Key Lab for Energy Materials and Chemical Engineering State Key Lab of Fine Chemicals Dalian University of Technology Dalian 116024 , China C. F. Zhang State Key Laboratory of Chemical Engineering East China University of Science and Technology Shanghai 200237 , China

Visual Tracking with Fully Convolutional Networks

Abstract: We propose a new approach for general object tracking with fully convolutional neural network. Instead of treating convolutional neural network (CNN) as a black-box feature extractor, we conduct in-depth study on the properties of CNN features offline pre-trained on massive image data and classification task on ImageNet. The discoveries motivate the design of our tracking system. It is found that convolutional layers in different levels characterize the target from different perspectives. A top layer encodes more semantic features and serves as a category detector, while a lower layer carries more discriminative information and can better separate the target from distracters with similar appearance. Both layers are jointly used with a switch mechanism during tracking. It is also found that for a tracking target, only a subset of neurons are relevant. A feature map selection method is developed to remove noisy and irrelevant feature maps, which can reduce computation redundancy and improve tracking accuracy. Extensive evaluation on the widely used tracking benchmark [36] shows that the proposed tacker outperforms the state-of-the-art significantly.

A Promising New Class of High-Temperature Alloys: Eutectic High-Entropy Alloys

Abstract: High-entropy alloys (HEAs) can have either high strength or high ductility, and a simultaneous achievement of both still constitutes a tough challenge. The inferior castability and compositional segregation of HEAs are also obstacles for their technological applications. To tackle these problems, here we proposed a novel strategy to design HEAs using the eutectic alloy concept, i.e. to achieve a microstructure composed of alternating soft fcc and hard bcc phases. As a manifestation of this concept, an AlCoCrFeNi 2.1 (atomic portion) eutectic high-entropy alloy (EHEA) was designed. The as-cast EHEA possessed a fine lamellar fcc/B2 microstructure, and showed an unprecedented combination of high tensile ductility and high fracture strength at room temperature. The excellent mechanical properties could be kept up to 700°C. This new alloy design strategy can be readily adapted to large-scale industrial production of HEAs with simultaneous high fracture strength and high ductility.

Deep networks for saliency detection via local estimation and global search

Abstract: This paper presents a saliency detection algorithm by integrating both local estimation and global search. In the local estimation stage, we detect local saliency by using a deep neural network (DNN-L) which learns local patch features to determine the saliency value of each pixel. The estimated local saliency maps are further refined by exploring the high level object concepts. In the global search stage, the local saliency map together with global contrast and geometric information are used as global features to describe a set of object candidate regions. Another deep neural network (DNN-G) is trained to predict the saliency score of each object region based on the global features. The final saliency map is generated by a weighted sum of salient object regions. Our method presents two interesting insights. First, local features learned by a supervised scheme can effectively capture local contrast, texture and shape information for saliency detection. Second, the complex relationship between different global saliency cues can be captured by deep networks and exploited principally rather than heuristically. Quantitative and qualitative experiments on several benchmark data sets demonstrate that our algorithm performs favorably against the state-of-the-art methods.

The triplet excited state of Bodipy: formation, modulation and application

Abstract: Boron dipyrromethene (Bodipy) is one of the most extensively investigated organic chromophores. Most of the investigations are focused on the singlet excited state of Bodipy, such as fluorescence. In stark contrast, the study of the triplet excited state of Bodipy is limited, but it is an emerging area, since the triplet state of Bodipy is tremendously important for several areas, such as the fundamental photochemistry study, photodynamic therapy (PDT), photocatalysis and triplet–triplet annihilation (TTA) upconversion. The recent developments in the study of the production, modulation and application of the triplet excited state of Bodipy are discussed in this review article. The formation of the triplet state of Bodipy upon photoexcitation, via the well known approach such as the heavy atom effect (including I, Br, Ru, Ir, etc.), and the new methods, such as using a spin converter (e.g. C60), charge recombination, exciton coupling and the doubly substituted excited state, are summarized. All the Bodipy-based triplet photosensitizers show strong absorption of visible or near IR light and the long-lived triplet excited state, which are important for the application of the triplet excited state in PDT or photocatalysis. Moreover, the methods for switching (or modulation) of the triplet excited state of Bodipy were discussed, such as those based on the photo-induced electron transfer (PET), by controlling the competing Forster-resonance-energy-transfer (FRET), or the intermolecular charge transfer (ICT). Controlling the triplet excited state will give functional molecules such as activatable PDT reagents or molecular devices. It is worth noting that switching of the singlet excited state and the triplet state of Bodipy may follow different principles. Application of the triplet excited state of Bodipy in PDT, hydrogen (H2) production, photoredox catalytic organic reactions and TTA upconversion were discussed. The challenges and the opportunities in these areas were briefly discussed.

Saliency detection via Cellular Automata

Abstract: In this paper, we introduce Cellular Automata-a dynamic evolution model to intuitively detect the salient object. First, we construct a background-based map using color and space contrast with the clustered boundary seeds. Then, a novel propagation mechanism dependent on Cellular Automata is proposed to exploit the intrinsic relevance of similar regions through interactions with neighbors. Impact factor matrix and coherence matrix are constructed to balance the influential power towards each cell's next state. The saliency values of all cells will be renovated simultaneously according to the proposed updating rule. It's surprising to find out that parallel evolution can improve all the existing methods to a similar level regardless of their original results. Finally, we present an integration algorithm in the Bayesian framework to take advantage of multiple saliency maps. Extensive experiments on six public datasets demonstrate that the proposed algorithm outperforms state-of-the-art methods.

High‐Yield Electrosynthesis of Hydrogen Peroxide from Oxygen Reduction by Hierarchically Porous Carbon

Abstract: H2O2 production by electroreduction of O2 is an attractive alternative to the current anthraquinone process, which is highly desirable for chemical industries and environmental remediation. However, it remains a great challenge to develop cost-effective electrocatalysts for H2O2 synthesis. Here, hierarchically porous carbon (HPC) was proposed for the electrosynthesis of H2O2 from O2 reduction. It exhibited high activity for O2 reduction and good H2O2 selectivity (95.0–70.2 %, most of them >90.0 % at pH 1–4 and >80.0 % at pH 7). High-yield H2O2 generation has been achieved on HPC with H2O2 concentrations of 222.6–62.0 mmol L−1 (2.5 h) and corresponding H2O2 production rates of 395.7–110.2 mmol h−1 g−1 at pH 1–7 and −0.5 V. Moreover, HPC was energy-efficient for H2O2 production with current efficiency of 81.8–70.8 %. The exceptional performance of HPC for electrosynthesis of H2O2 could be attributed to its high content of sp3-C and defects, large surface area and fast mass transfer.

Recent Progress on Hole‐Transporting Materials for Emerging Organometal Halide Perovskite Solar Cells

Abstract: In less than three years, the photovoltaic community has witnessed a rapid emergence of a new class of solid-state heterojunction solar cells based on solution-processable organometal halide perovskite absorbers. The energy conversion efficiency of solid-state perovskite solar cells (PSCs) has been quickly increased to a certified value of 20.1% by the end of 2014 because of their unique characteristics, such as a broad spectral absorption range, large absorption coefficient, high charge carrier mobility and diffusion length. Here, the focus is specifically on recent developments of hole-transporting materials (HTMs) in PSCs, which are essential components for achieving high solar cell efficiencies. Some fundamentals with regard to PSCs are first presented, including the history of PSCs, device architectures and general operational principles of PSCs as well as various techniques developed for the fabrications of uniform and dense perovskite complexes. A broad range of the state-of-the-art HTMs being used in PSCs are then discussed in detail. Finally, an outlook on the design of more efficient HTMs for highly efficient PSCs is addressed.

Efficient Electrochemical Reduction of Carbon Dioxide to Acetate on Nitrogen-Doped Nanodiamond

Abstract: Electrochemical reduction of CO2 is an attractive technique for reducing CO2 emission and converting it into useful chemicals, but it suffers from high overpotential, low efficiency or poor product selectivity. Here, N-doped nanodiamond/Si rod array (NDD/Si RA) was proposed as an efficient nonmetallic electrocatalyst for CO2 reduction. It preferentially and rapidly converted CO2 to acetate over formate with an onset potential of −0.36 V (vs RHE), overcoming the usual limitation of low selectivity for C2 products. Moreover, faradic efficiency of 91.2–91.8% has been achieved for CO2 reduction at −0.8 to −1.0 V. Its superior performance for CO2 reduction can be attributed to its high overpotential for hydrogen evolution and N doping, where N-sp3C species was highly active for CO2 reduction. Electrokinetic data and in situ infrared spectrum revealed the main pathway for CO2 reduction might be CO2 → CO2•– → (COO)2• → CH3COO–.

Fluorescent, MRI, and colorimetric chemical sensors for the first-row d-block metal ions

Abstract: Transition metals (d-blocks) are recognized as playing critical roles in biology, and they most often act as cofactors in diverse enzymes; however, improper regulation of transition metal stores is also connected to serious disorders. Therefore, the monitoring and imaging of transition metals are significant for biological research as well as clinical diagnosis. In this article, efforts have been made to review the chemical sensors that have been developed for the detection of the first-row d-block metals (except Cu and Zn): Cr, Mn, Fe, Co, and Ni. We focus on the development of fluorescent sensors (fall into three classes: “turn-off”, “turn-on”, and ratiometric), colorimetric sensors, and responsive MRI contrast agents for these transition metals (242 references). Future work will be likely to fill in the blanks: (1) sensors for Sc, Ti, and V; (2) MRI sensors for Cr, Mn, Co, Ni; (3) ratiometric fluorescent sensors for Cr6+, Mn2+, and Ni2+, explore new ways of sensing Fe3+ or Cr3+ without the proton interference, as well as extend applications of MRI sensors to living systems.

Recent advances in dye-sensitized photoelectrochemical cells for solar hydrogen production based on molecular components

Abstract: Conceptually new research on dye-sensitized photoelectrochemical cells (DS-PECs), through which solar-driven water splitting to generate solar fuel in the form of hydrogen is realized, has attracted growing interest in the past few years. DS-PECs are based on the configurations of dye-sensitized solar cells (DSCs), but with an aim to drive the two half reactions of water splitting at physically separated two compartments (electrodes) rather than to generate electrical power. Herein, we review some of the recent advances in the design and construction of functional DS-PECs for visible light-driven water splitting together with some comments on the performance of these devices. Future challenges towards the development of more efficient dye-sensitized photoelectrochemical devices are addressed in the end.

A new image encryption algorithm based on non-adjacent coupled map lattices

Abstract: We propose an image encryption scheme based on a new spatiotemporal chaotic system.The encryption scheme is not the one time pad encryption.The proposed image encryption has a large key space and high security. We propose a new image encryption algorithm which is based on the spatiotemporal non-adjacent coupled map lattices. The system of non-adjacent coupled map lattices has more outstanding cryptography features in dynamics than the logistic map or coupled map lattices does. In the proposed image encryption, we employ a bit-level pixel permutation strategy which enables bit planes of pixels permute mutually without any extra storage space. Simulations have been carried out and the results demonstrate the superior security and high efficiency of the proposed algorithm.

Introduction to: Special Issue on Smartphone-Based Interactive Technologies, Systems, and Applications

Abstract: Smartphones (or smart mobile devices) have now truly become a ubiquitous computing device, a computer that the late Mark Weiser envisioned in his ubiquitous computing manifesto. Many applications that could only have been dreamed of have now become a reality due to the powerful computing resources, display, sensing, and networking capabilities of smartphones. With applications ranging from productivity, entertainment, enterprise, social networking, communications, and mixed reality, the smartphone is the “swiss army knife” of it all. However, there are still many untapped elements and unlimited possibilities: Smartphones can provide next-generation interactive systems with more intuitive and intelligent technologies and applications that have not been explored much in detail, especially through the use of mobile computing, sensing, and networking capabilities. Making uses of cyber and physical data accessible by smartphones at a location, new cyber-physical interactive technologies and systems can be designed and integrated to create novel functionalities, methods, and intelligences to interact with humans and environments for better social experiences, as well as more intelligent services and creative applications, such as recommendation systems, advertising platforms, and gaming applications that are interactive to the user smartphones on the spot in a physical environment and situation. This special issue of ACM Transactions on Multimedia Computing, Communications and Applications (TOMM) provides an opportunity to attract and bring together mobile computing, cyber-physical systems, ubiquitous computing, social computing, wireless networking, and multimedia communications researchers along with user interface designers and practitioners with diverse backgrounds to contribute articles on theoretical, practical, and methodological issues for next-generation interactive technologies, systems, and applications using smartphones. There were a record number of submissions (38 in total) for this special issue of ACM TOMM. Twelve high-quality, creative, and interesting articles were selected and accepted, which discuss various challenges and emerging directions of smartphone-based interactive technologies, systems, and applications. This special issue starts off with 5 articles concerning the technologies and applications for better uses and creations of visual/3D images and augmented reality (AR) in the smartphones The first article by Zhu et al. is titled “ShotVis: Smartphone-Based Visualization of OCR Information from Images” and it presents an approach to help smartphone users to easily read and organize text-based data captured by the smartphone’s camera. The captured images with textual data are first processed by optical character recognition, and the recognized information is readable through various intuitive visualization techniques selected and refined by smartphone users through on-screen interactions.

A Layered‐Nanospace‐Confinement Strategy for the Synthesis of Two‐Dimensional Porous Carbon Nanosheets for High‐Rate Performance Supercapacitors

Abstract: A general approach is developed for the synthesis of 2D porous carbon nanosheets (PCNS) from bio-sources derived carbon precursors (gelatin) by an integrated procedure of intercalation, pyrolysis, and activation. Montmorillonite with layered nanospace is used as a nanotemplate or nanoreactor to confine and modulate the transformation of gelatin, further leading to the formation of 2D nanosheet-shaped carbon materials. The as-made 2D PCNS exhibits a significantly improved rate performance, with a high specific capacitance of 246 F g−1 and capacitance retention of 82% at 100 A g−1, being nearly twice that of microsized activated carbon particulates directly from gelatin (131 F g−1, 44%). The shortened ion transport distance in the nanoscaled dimension and modulated porous structure is responsible for such an enhanced superior rate capability. More importantly, the present strategy can be extended to other bio-sources to create 2D PCNS as electrode materials with high-rate performance. This will also provide a potential strategy for configuring 2D nanostructured carbon electrode materials with a short ion transport distance for supercapacitors and other carbon-related energy storage and conversion devices.

Organic Dye-Sensitized Tandem Photoelectrochemical Cell for Light Driven Total Water Splitting.

Abstract: Light driven water splitting was achieved by a tandem dye-sensitized photoelectrochemical cell with two photoactive electrodes. The photoanode is constituted by an organic dye L0 as photosensitizer and a molecular complex Ru1 as water oxidation catalyst on meso-porous TiO2, while the photocathode is constructed with an organic dye P1 as photoabsorber and a molecular complex Co1 as hydrogen generation catalyst on nanostructured NiO. By combining the photocathode and the photoanode, this tandem DS-PEC cell can split water by visible light under neutral pH conditions without applying any bias.

Salient object detection via bootstrap learning

Abstract: We propose a bootstrap learning algorithm for salient object detection in which both weak and strong models are exploited. First, a weak saliency map is constructed based on image priors to generate training samples for a strong model. Second, a strong classifier based on samples directly from an input image is learned to detect salient pixels. Results from multiscale saliency maps are integrated to further improve the detection performance. Extensive experiments on six benchmark datasets demonstrate that the proposed bootstrap learning algorithm performs favorably against the state-of-the-art saliency detection methods. Furthermore, we show that the proposed bootstrap learning approach can be easily applied to other bottom-up saliency models for significant improvement.

Al2O3 Nanosheets Rich in Pentacoordinate Al(3+) Ions Stabilize Pt-Sn Clusters for Propane Dehydrogenation.

Abstract: In heterogeneous catalysis, supports play a crucial role in modulating the geometric and electronic structure of the active metal phase for optimizing the catalytic performance. A γ-Al2O3 nanosheet that contains 27% pentacoordinate Al(3+) sites can nicely disperse and stabilize raft-like Pt-Sn clusters as a result of strong interactions between metal and support. Consequently, there are strong electronic interactions between the Pt and Sn atoms, resulting in an increase in the electron density of the Pt sites. When used in the propane dehydrogenation reaction, this catalyst displayed an excellent specific activity for propylene formation with >99% selectivity, and superior anti-coking and anti-sintering properties. Its exceptional ability to maintain the high activity and stability at ultrahigh space velocities further showed that the sheet construction of the catalyst facilitated the kinetic transfer process.