Energy and air? The impact of energy efficiency improvement on air quality in China.

The global economic growth is hindered by resources shortage, energy demand, air pollution and climate. Energy efficiency can reduce some pollutants while potentially increase others. This study refers to sulfur dioxide (SO2), nitrogen oxides (NOx), and dust and smoke (DS) as primary pollutants to distinguish it from secondary ones. The influence of energy efficiency, socioeconomic, and natural climatic factors on air quality is analyzed under the theory of STIRPAT. It is highly coupled between energy efficiency and the spatial distribution of air quality. Increased energy efficiency can improve air quality by reducing SO2 and NOx, but the impact on DS is insignificant. Air pollutants decrease by about 0.531% for every 1% increase in temperature and 0.105% for every 1% increase in precipitation. Consumption will reduce air pollution, and there is an inverted U-shaped relationship between population density, economic scale, urbanization, technology innovation, and air pollution. It is worth mentioning that this work adds temperature and precipitation to the STIRPAT as natural climatic factors, analyzing the impact of energy efficiency on air pollution under the two-factor restrictions of socioeconomic and natural climatic factors. Finally, management suggestions are made to improve air quality.

Anode-free Na metal batteries developed by nearly fully reversible Na plating on the Zn surface.

The anode-free battery architecture has recently emerged as a promising platform for lithium and sodium metal batteries as it not only offers the highest possible energy density, but also eliminates the need for handling hazardous metal electrodes during cell manufacturing. However, such batteries usually suffer from much faster capacity decay and are much more sensitive to even trace levels of irreversible side reactions on the anode, especially for the more reactive Na metal. This work systematically investigates electrochemical interfaces for Na plating and stripping and describes the use of the Zn surface to develop nearly fully reversible Na anodes with 1.0 M NaPF6 in a diglyme-based electrolyte. The high performance includes consistently higher than 99.9% faradaic efficiencies for a wide range of cycling currents between 0.5 and 10 mA cm-2, much more stable interfacial resistance and nearly no formation of mossy Na after 500 cycles compared with conventional Al and Cu surfaces. This improved reversibility was further confirmed under lean electrolyte conditions with a wide range of electrolyte concentrations and cycling temperatures and can be attributed to the strong interfacial binding and intrinsic sodiophilic properties of the Zn surface with Na, which not only ensured uniform Na plating but also eliminated most side reactions that would otherwise cause electrolyte depletion. As a result, full cells assembled with Na-free Zn foil and a high capacity Na3V2(PO4)3 cathode delivered ∼90% capacity retention for 100 cycles, higher than the 73% retention of Cu foils and much higher than the 39% retention of Al foils. This work provides new approaches to enable stable cycling of anode-free batteries and contribute to their applications in practical devices.

Bidirectional Tandem Electrocatalysis Manipulated Sulfur Speciation Pathway for High-Capacity and Stable Na-S Battery.

The sluggish polysulfide redox kinetics and the uncontrollable sulfur speciation pathway, leading to serious shuttling effect and high activation barrier associated with sulfur cathode. We describe here the use of core-shell structured composite matrixes containing abundant catalytic sites for nearly fully reversible cycling of sulfur cathodes for Na-S batteries. The bidirectional tandem electrocatalysis provide successive reversible conversion of both long- and short-chain polysulfides, whereas Fe2 O3 accelerates Na2 S8 /Na2 S6 to Na2 S4 conversion and the redox-active Fe(CN)6 4- -doped polypyrrole shell catalyzes Na2 S4 reduction to Na2 S. The electrochemically reactive Na2 S can be readily charged back to sulfur with minimal overpotential. Simultaneously, stable cycling of Na-S pouch cell with a high reversible capacity of 696 mAh g-1 is also demonstrated. The bidirectional confined tandem catalysis renders the manipulation of sulfur redox electrochemistry for practical Na-S cells.

Pattern recognition algorithm and software design of an optical fiber vibration signal based on Φ-optical time-domain reflectometry.

A phase-sensitive optical time-domain reflectometry with a detection distance of 10 km is used in this paper to recognize and to detect in real time events along the perimeter security monitoring system. To optimize the signal processing in the software system and achieve the design of distributed optical fiber vibration signal of the perimeter security monitoring system, a two-level vibration pattern recognition scheme based on the power spectral estimation is proposed. The monitoring system software of the proposed algorithm is designed and implemented, as well as the functional modules involved in the design of the software system. The experimental tests of the whole system show that the proposed algorithm can effectively identify in real time any intrusion event along the sensing cable, with an intrusion detection rate greater than 95%, including false alarms. Also, the corresponding monitoring system software can display the data collected in real time, with a processing time of around 1.6 s, which proves its reliability, thereby ensuring the system's validity.

Dual-Excitation Polyoxometalate-Based Frameworks for One-Pot Light-Driven Hydrogen Evolution and Oxidative Dehydrogenation.

Dehydrogenation of the tetrahydroisoquinoline derivatives coupled with hydrogen production is important for hydrogen storage applications. Herein, we formulated a new system that embedded Dawson-type polyoxometalates as efficient photosensitizers into the pores of redox-active coordination polymers for the light-driven photocatalytic oxidative Mannich reaction and hydrogen evolution. In the designed Co-POM polymer, UV light excitation gives the excited state of the Dawson-type polyoxometalate first to oxidize electron donors or substrates; the reduced form (i.e., heteropolyblue) adsorbs visible light to achieve a new excited state, which reduced the cobalt redox sites and facilitates hydrogen evolution reaction. The photosensitizer recovered to the ground state, completing the catalytic cycle. Under the optimized conditions, Co-POM enabled the hydrogen evolution and dehydrogenation of tetrahydroisoquinoline without the presence of any other additives. The high catalytic efficiency and robustness indicated the advantages of the combining functional polyoxometalate-based catalysts and porous characters of the coordination polymers for the development of highly active heterogeneous catalysts.

Binding of anions in triply interlocked coordination catenanes and dynamic allostery for dehalogenation reactions.

By synergistic combination of multicomponent self-assembly and template-directed approaches, triply interlocked metal organic catenanes that consist of two isolated chirally identical tetrahedrons were constructed and stabilized as thermodynamic minima. In the presence of suitable template anions, the structural conversion from the isolated tetrahedral conformers into locked catenanes occurred via the cleavage of an intrinsically reversible coordination bond in each of the tetrahedrons, followed by the reengineering and interlocking of two fragments with the regeneration of the broken coordination bonds. The presence of several kinds of individual pocket that were attributed to the triply interlocked patterns enabled the possibility of encapsulating different anions, allowing the dynamic allostery between the unlocked/locked conformers to promote the dehalogenation reaction of 3-bromo-cyclohexene efficiently, as with the use of dehalogenase enzymes. The interlocked structures could be unlocked into two individual tetrahedrons through removal of the well-matched anion templates. The stability and reversibility of the locked/unlocked structures were further confirmed by the catching/releasing process that accompanied emission switching, providing opportunities for the system to be a dynamic molecular logic system.

Automatic Registration of Images With Inconsistent Content Through Line-Support Region Segmentation and Geometrical Outlier Removal.

The implementation of automatic image registration is still difficult in various applications. In this paper, an automatic image registration approach through line-support region segmentation and geometrical outlier removal is proposed. This new approach is designed to address the problems associated with the registration of images with affine deformations and inconsistent content, such as remote sensing images with different spectral content or noise interference, or map images with inconsistent annotations. To begin with, line-support regions, namely a straight region whose points share roughly the same image gradient angle, are extracted to address the issues of inconsistent content existing in images. To alleviate the incompleteness of line segments, an iterative strategy with multi-resolution is employed to preserve global structures that are masked at full resolution by image details or noise. Then, geometrical outlier removal is developed to provide reliable feature point matching, which is based on affine-invariant geometrical classifications for corresponding matches initialized by scale invariant feature transform. The candidate outliers are selected by comparing the disparity of accumulated classifications among all matches, instead of conventional methods which only rely on local geometrical relations. Various image sets have been considered in this paper for the evaluation of the proposed approach, including aerial images with simulated affine deformations, remote sensing optical and synthetic aperture radar images taken at different situations (multispectral, multisensor, and multitemporal), and map images with inconsistent annotations. Experimental results demonstrate the superior performance of the proposed method over the existing approaches for the whole data set.

High-resolution structure of podovirus tail adaptor suggests repositioning of an octad motif that mediates the sequential tail assembly.

The sophisticated tail structures of DNA bacteriophages play essential roles in life cycles. Podoviruses P22 and Sf6 have short tails consisting of multiple proteins, among which is a tail adaptor protein that connects the portal protein to the other tail proteins. Assembly of the tail has been shown to occur in a sequential manner to ensure proper molecular interactions, but the underlying mechanism remains to be understood. Here, we report the high-resolution structure of the tail adaptor protein gp7 from phage Sf6. The structure exhibits distinct distribution of opposite charges on two sides of the molecule. A gp7 dodecameric ring model shows an entirely negatively charged surface, suggesting that the assembly of the dodecamer occurs through head-to-tail interactions of the bipolar monomers. The N-terminal helix-loop structure undergoes rearrangement compared with that of the P22 homolog complexed with the portal, which is achieved by repositioning of two consecutive repeats of a conserved octad sequence motif. We propose that the conformation of the N-terminal helix-loop observed in the Sf6-gp7 and P22 portal:gp4 complex represents the pre- and postassembly state, respectively. Such motif repositioning may serve as a conformational switch that creates the docking site for the tail nozzle only after the assembly of adaptor protein to the portal. In addition, the C-terminal portion of gp7 shows conformational flexibility, indicating an induced fit on binding to the portal. These results provide insight into the mechanistic role of the adaptor protein in mediating the sequential assembly of the phage tail.

Plasmonic induced triple-band absorber for sensor application.

We design and investigate a triple-band plasmonic metamaterial absorber (PMA) for sensor application. The underlying mechanism is investigated theoretically and numerically. Three characteristic absorption peaks are demonstrated to be induced by different plasmonic modes which lead to different responses for the plasmonic sensor. These modes show great improvement for the sensitivity and accuracy of the plasmonic sensors. This triple-band plasmonic metamaterial optical absorber has great potential to improve the performance in practical applications.