Feature extraction for license plate location based on L0-norm smoothing

We propose a simple feature extraction algorithm for license plate location, which can reduce the occurrence of pseudo-licenses significantly. Our scheme arises from a novel L-0 -norm image smoothing, in which the multiple local textures in the complex backgrounds can be suppressed remarkably without changing the structures and edges of the license objects. Due to this "edgeaware" property, we then combine a feature filtering with an efficient binarized image, a simple multi-scale image analysis algorithm, to remove the potential false license plates. Finally, we extract license plates with a projection method. Experimental results show the proposed method provides a flexible and powerful way to the license plate location in complex backgrounds

MXene molecular sieving membranes for highly efficient gas separation

Molecular sieving membranes with sufficient and uniform nanochannels that break the permeability-selectivity trade-off are desirable for energy-efficient gas separation, and the arising two-dimensional (2D) materials provide new routes for membrane development. However, for 2D lamellar membranes, disordered interlayer nanochannels for mass transport are usually formed between randomly stacked neighboring nanosheets, which is obstructive for highly efficient separation. Therefore, manufacturing lamellar membranes with highly ordered nanochannel structures for fast and precise molecular sieving is still challenging. Here, we report on lamellar stacked MXene membranes with aligned and regular subnanometer channels, taking advantage of the abundant surface-terminating groups on the MXene nanosheets, which exhibit excellent gas separation performance with H2 permeability >2200 Barrer and H2/CO2 selectivity >160, superior to the state-of-the-art membranes. The results of molecular dynamics simulations quantitatively support the experiments, confirming the subnanometer interlayer spacing between the neighboring MXene nanosheets as molecular sieving channels for gas separation

A breast cancer stem cell niche supported by juxtacrine signalling from monocytes and macrophages

The cell-biological program termed the epithelial-mesenchymal transition (EMT) confers on cancer cells mesenchymal traits and an ability to enter the cancer stem cell (CSC) state. However, the interactions between CSCs and their surrounding microenvironment are poorly understood. Here we show that tumour-associated monocytes and macrophages (TAMs) create a CSC niche through juxtacrine signalling with CSCs. We performed quantitative proteomic profiling and found that the EMT program upregulates the expression of CD90, also known as Thy1, and EphA4, which mediate the physical interactions of CSCs with TAMs by directly binding with their respective counter-receptors on these cells. In response, the EphA4 receptor on the carcinoma cells activates Src and NF-κ B. In turn, NF-κ B in the CSCs induces the secretion of a variety of cytokines that serve to sustain the stem cell state. Indeed, admixed macrophages enhance the CSC activities of carcinoma cells. These findings underscore the significance of TAMs as important components of the CSC niche.National Institutes of Health (U.S.) (Grant R01-CA078461)National Institutes of Health (U.S.) (Grant P01-CA080111)National Institutes of Health (U.S.) (Grant U54-CA163109

Application of Gas Chromatography Mass Spectrometry in Tar Analysis from Underground Gasification

The study of tar behaviors in underground coal gasification (UCG) is essential for pollution control, system safety and conversion efficiency; however, existing studies have only focused on tar in products without revealing tar evolution in the reaction zone, and the experimental conditions in reported work are far from those in the real situation. In this work, tar behaviors were studied with a self-developed apparatus to simulate the UCG process. During the experiments, the sampling method along the gasification channel was used to collect tar at different positions; the gasification object was a large raw coal block 460 mm × 230 mm × 230 mm in size, and the flow rate of the inlet gas was adjusted according to the composition of products. The tar samples were not only taken from the outlet, but also from the reaction zone, and then analyzed using gas chromatography mass spectrometry. For all the tar samples, C15H13N and its isomer were the most abundant compounds, with a total percentage greater than 14%. Most of the top five chemicals contained more than nine carbon atoms in their molecular formulae, indicating that more heavy tar than light tar is formed by low-temperature pyrolysis. Compared with the upstream tar, the downstream tar had fewer PAHs and a lower boiling point, due to the decomposition of the heavy tar. The downstream tar contained more of the element fluorine (F) than upstream and outlet tars, indicating that tar pollution remaining in the reaction zone cannot be evaluated by monitoring the outlet tar

Reaction model and thermodynamic properties between sulfur-containing active groups and oxygen during coal self-heating

To further study the mechanism of coal self-heating, the reaction sequences and thermodynamic properties between sulfur-containing groups and oxygen during coal self-heating were analyzed. The benzyl mercaptan and diphenyl sulfide were selected as typical sulfur-containing structures existing in coal. Their structural parameters, frontier orbital characteristics, and thermodynamic parameters were analyzed through quantum chemistry calculation and their detailed reaction sequences with oxygen were proposed. The results indicate that the thiol structure in coal can easily react with oxygen at low temperatures and release large amounts of heat (146.70 kJ/mol) during coal self-heating, providing active free radicals and energy for subsequent chain reactions of coal spontaneous combustion. The oxidation reaction between the thioether structure and oxygen cannot occur at room temperature. With the accumulation of heat, thioether gradually becomes active and reacts with oxygen to form sulfoxide and release an enormous amount of heat (248.09 kJ/mol), which can be further oxidized to sulfone with an increase in temperature. The reaction models of thiol and thioether groups during coal self-heating were proposed, which involves eight main reaction sequences (R1∼R8). It indicates that the reactions of thiol and thioether groups play crucial roles during the evolution of coal self-heating, with a slow oxidation stage at low temperatures and an accelerated oxidation stage at high temperatures.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Characteristics of Pyrolysis and Low Oxygen Combustion of Long Flame Coal and Reburning of Residues

To further understand the problems of coal combustion and coalfield fire reignition, this paper researched the reaction characteristics of coal pyrolysis and low oxygen combustion and the reburning oxidation characteristics of residual structure by thermal analysis methods. The results show that temperature promotes both pyrolysis and low oxygen combustion reactions, but low oxygen combustion reaction is more sensitive to temperature changes. As the constant temperature rises, the mass reduction rate of low oxygen combustion of coal samples reaches 80% on average, which is 4 times that of pyrolysis, and the variations of thermogravimetric parameters are also significantly higher than those of pyrolysis. However, the higher the pyrolysis degree of the residues, the stronger their oxidizability, which greatly enhances the intensity and concentration of the secondary combustion, and the mass of residues is reduced by 90% on average. Conversely, because the combustible components are continuously consumed during low oxygen combustion, the reburning characteristics of residues become less obvious. For instance, the weight loss rate slows down, the burning becomes dispersed, and the burning intensity is weakened. In addition, the heat release is reduced from 8662 to 444.5 J/g, and the change trend is just opposite to that of pyrolysis. The above results show that as the constant temperature rises, the pyrolysis reaction greatly shortens the reburning process, while the low oxygen combustion reaction largely inhibits the reburning

In Situ FTIR Study of Real-Time Changes of Active Groups during Oxygen-Free Reaction of Coal

The distribution of functional groups in two different rank coal samples and their real-time changes during the oxygen-free reaction of coal were tested. An in situ FTIR system was designed to test the real-time changes of functional groups during coal reaction. The real-time changes of aliphatic hydrocarbon groups and oxygen-containing groups were analyzed using the in situ FTIR method. The results show that the distribution of functional groups and their changes are various for different ranks of coals. The quantity of active groups in low-rank coals is larger than that in high-rank coals. For the anthracite coal sample, the quantities of aliphatic hydrocarbon and oxygen-containing groups increase with the rise of coal temperature. For the lignite coal sample, the quantity of aliphatic carbon groups decreases from 30 to 70 °C, then increases with the temperature rise. The oxygen-containing groups of the lignite coal sample have two different changing trends, that is, an increase with temperature rise, and a decrease at the initial temperature stage, followed by increasing with temperature rise. These phenomena are resulted from the difference of chemical activities of various active groups. This study provides a new method for further study of coal reaction at the level of active groups and explains the generation process of gaseous products during the oxygen-free reaction of coal

Free-standing sulfur host based on titanium-dioxide-modified porous-carbon nanofibers for lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries are regarded as a promising next-generation electrical-energy-storage technology due to their low cost and high theoretical energy density. Furthermore, flexible and wearable electronics urgently requires their power sources to be mechanically robust and flexible. However, the effective progress of high-performance, flexible Li-S batteries is still hindered by the poor conductivity of sulfur cathodes and the dissolution of lithium polysulfides as well as the weak mechanical properties of sulfur cathodes. Herein, a new type of flexible porous carbon nanofiber film modified with graphene and ultrafine polar TiO2 nanoparticles is designed as a sulfur host, in which the artful structure enabled the highly efficient dispersion of sulfur for a high capacity and a strong confinement capability of lithium polysulfides, resulting in prolonged cycle life. Thus, the cathode shows an extremely high initial specific discharge capacity of 1501 mA h g−1 at 0.1 C and an excellent rate capability of 668 mA h g−1 at 5 C as well as prolonged cycling stability. The artful design provides a facile method to fabricate high-performance, flexible sulfur cathodes for Li-S batteries

Low-Voltage Electrolytic Hydrogen Production Derived from Efficient Water and Ethanol Oxidation on Fluorine-Modified FeOOH Anode

Highly active, earth-abundant anode catalysts are urgently required for the development of electrolytic devices for hydrogen generation. However, the reaction efficiencies of most developed electrocatalysts have been intrinsically limited due to their insufficient adsorption of reactants leading to high energy intermediates. Here, we establish that electronegative fluorine can moderate the binding energy between the Fe sites (FeOOH) and reactants (OH^– or C₂H₅O^–), resulting in more optimized adsorption, and can enhance the positive charge densities on the Fe sites to facilitate oxygen evolution reaction (OER) and ethanol oxidation. Consequently, a low electrolytic voltage (1.43 V to achieve 10 mA cm^–2) for H₂ production was obtained by integrating the efficiently anodic behaviors of OER and ethanol oxidation. The results reported herein point to fluorine moderation as a promising pathway for developing optimal electrocatalysts and contribute to ongoing efforts of mimicking water splitting