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This study investigates the failure mechanism and strengthening effect of a shield tunnel lining structure reinforced via steel plates with corbels. A detailed three-dimensional (3D) numerical model is established for the staggered-joint segmental lining structure of an actual shield tunnel in the Kunming metro-system, which is then validated via a full-scale simulation experiment of the shield tunnel segmental lining structure. Then, the actual loading conditions of the staggered-joint shield tunnel segmental lining structure in the Kunming metro-system are simulated, and the mechanical responses of the segmental lining are analysed in terms of the variation in its diameter, opening amount of the joints and stress of the bolts. The ultimate load-bearing capacity of the lining structure reinforced using steel plates with corbels is improved to 610 kN, which is 41.9% higher than the unreinforced structure with an ultimate load-bearing capacity of 430 kN. Moreover, the strengthening effect of the reinforcement using steel plates with corbels is discussed considering actual field monitoring data and other reinforcement methods. It is concluded that the results of this paper can provide an effective reference for similar reinforcement schemes of shield tunnels. The defined classification criteria can be adopted to determine the deformation stage of reinforced shield tunnels. [ABSTRACT FROM AUTHOR]

Ship detection is one of important applications for synthetic aperture radar (SAR). Speckle effects usually make SAR image understanding difficult and speckle reduction becomes a necessary pre-processing step for majority SAR applications. This work examines different speckle reduction methods on SAR ship detection performances. It is found out that the influences of different speckle filters are significant which can be positive or negative. However, how to select a suitable combination of speckle filters and ship detectors is lack of theoretical basis and is also data-orientated. To overcome this limitation, a speckle-free SAR ship detection approach is proposed. A similar pixel number (SPN) indicator which can effectively identify salient target is derived, during the similar pixel selection procedure with the context covariance matrix (CCM) similarity test. The underlying principle lies in that ship and sea clutter candidates show different properties of homogeneity within a moving window and the SPN indicator can clearly reflect their differences. The sensitivity and efficiency of the SPN indicator is examined and demonstrated. Then, a speckle-free SAR ship detection approach is established based on the SPN indicator. The detection flowchart is also given. Experimental and comparison studies are carried out with three kinds of spaceborne SAR datasets in terms of different polarizations. The proposed method achieves the best SAR ship detection performances with the highest figures of merits (FoM) of 97.14%, 90.32% and 93.75% for the used Radarsat-2, GaoFen-3 and Sentinel-1 datasets, accordingly. [ABSTRACT FROM AUTHOR]

Blue fluorescent materials are an essential part of commercial OLED displays and lightings. However, the market lacks highly efficient, short-emission wavelength blue fluorescent materials. Herein, two new blue fluorescent materials, SAFPI-3 and SAFPI-2, are developed based on a phenanthroimidazole derivative and spiro fluorene triphenylamine by replacing the substitution sites, which tactfully utilize the spatial configuration of the molecules to achieve higher external quantum efficiency and a shorter emission wavelength at the same time. Furthermore, the versatility of SAFPI-3 and SAFPI-2 can be demonstrated as non-doped emitters for blue OLEDs and as the hosts of yellow phosphorescent OLEDs, which have achieved a high external quantum efficiency of 23.98% with extremely low-efficiency roll-off. [Display omitted] • Two novel blue fluorescent isomers are developed. • SAFPI-3 -based non-doped OLED achieves a high EQE of 4.99% with EL emission peak at 432 nm. • OLED using SAFPI-3 as host obtains high EQE of 23.98% with negligible efficiency roll-off. [ABSTRACT FROM AUTHOR]

Speckle filtering of synthetic aperture radar (SAR) image is a necessary pre-processing for many subsequent applications. The challenge lies in how to adaptively select a sufficient number of similar pixels for an unbiased estimator generation. A novel SAR speckle filter is proposed and the core idea contains two aspects. Firstly, a context covariance matrix representation is developed within a local neighborhood to characterize the contexture information. Then, the Wishart statistic test is extended to examine the similarity of context covariance matrices. The extended similarity test indicator derived from context covariance matrices is verified to be sensitive for similar pixel localization. Thereafter, a sample averaging estimator is adopted based on the similar samples determined by the context covariance matrices similarity test (the proposed method is named as the CCM+SimiTest). Furthermore, a fast similarity test computation scheme is established which can handle large images smoothly even with a normal laptop. Intensive experimental studies with Radarsat-2, MiniSAR and ALOS-2 datasets are carried out. Comparisons with several state-of-the-art methods from both subjective and objective viewpoints demonstrate the superiority of the proposed method. [ABSTRACT FROM AUTHOR]

A cobalt‐catalyzed annulation of o‐phenylenediamines and internal alkynes for the synthesis of quinoxalines is developed. This method provides a variety of quinoxalines in good to high yields under a simple and mild reaction conditions with molecular O2 as a terminal oxidant. Preliminary mechanistic studies show that a novel reaction mechanism is involved in the current reaction, which is different from the previous reported dicarbonyl compound mechanism via the oxidation of the alkyne. [ABSTRACT FROM AUTHOR]

A quick response to a large-scale natural disaster such as earthquake and tsunami is vital to mitigate further loss. Remote sensing, especially the spaceborne sensors, provides the possibility to monitor a very large scale area in a short time and with regular revisit circle. Damage ranges and damage levels of the destructed urban areas are extremely important information for rescue planning after an event. Rapid mapping of the urban damage levels with synthetic aperture radar (SAR) is still challenging. Compared with single-polarization SAR, fully polarimetric SAR (PolSAR) has a better potential to understand the urban damage from the viewpoint of scattering mechanism investigation. In radar polarimetry, the dominant double-bounce scattering mechanism in an urban area is primarily induced by the ground-wall structures and can reflect the changes of these structures. In this sense, urban damage level in terms of destroyed ground-wall structures can be indicated by the reduction of the dominant double-bounce scattering mechanism, which is the basis of this study. This work first establishes and validates the linear relationship between the urban damage level and the proposed polarimetric damage index using polarimetric model-based decomposition. Then, efforts are focused on the development of a rapid urban damage level mapping technique which mainly includes two steps of urban area extraction and polarimetric damage level estimation. The 3.11 East Japan earthquake and tsunami inducing great-scale destruction are adopted for study using L-band multitemporal spaceborne PolSAR data. Experimental studies demonstrate that the estimated damage levels are closely consistent to the ground-truth. The final urban damage level map for the full scene is generated thereafter. Results achieved in this study further validate the necessity of exploring fully polarimetric technique for damage assessment. [ABSTRACT FROM PUBLISHER]

[Display omitted] • Novel recyclable citric acid-based polyamide hot melt adhesive. • Simultaneous strong and tough adhesion. • Strong fluorescence effect in the case of no chromophore groups. • Open a window for designing multifunctional hot melt adhesive. Achieving strong and tough adhesion is a great challenge due to simultaneous requirement of strength and ductility, and meanwhile permanent adhesives for the resistance against high debonding forces are facing difficulties in removing from the substrate and recycling. Herein, we report citric acid-based polyamide hot melt adhesives (PAHMAs) with tailor-made tough adhesion, which were synthesized by melt polymerization of citrate polyamide and polyethylene glycol (PEG). The resulting PAHMAs simultaneously attained the adhesion strength of 4.5 MPa and work of debonding of 2382 N/m, achieving strong and tough adhesion of different substrates such as glass, steel, etc. By adjusting the citric acid enhanced noncovalent interactions and the energy-dissipating role of soft phase PEG, the adhesion strength using PAHMAs can be tailored from strong to strong and tough in the strength range of 1.5–10.8 MPa. Roles of multiple hydrogen-bonds (H-bonds) for high adhesion strength and flexible chains PEG for dispersing energy in debonding were discussed deeply. Interestingly, PAHMAs also display stable cycle adhesion capability due to the dynamic crosslinking feature of H-bonds, maintaining high adhesion strength after 4th cycle. Additionally, the PAHMAs exhibit strong fluorescence in the case of no traditional chromophore groups, showing the fluorescent anti-counterfeiting application value. Design of dynamic crosslinking and long energy-dissipating chains may open up new thoughts of recyclable multifunctional strong and tough polyamide adhesives. [ABSTRACT FROM AUTHOR]

Crop discrimination is a necessary step for most agricultural monitoring systems. Radar polarimetric responses from various crops strongly relate to the types and orientations of the local scatterers, which makes the discrimination still difficult using the polarimetric synthetic aperture radar (PolSAR) technique. This work provides a new approach by investigating and utilizing the characteristics of polarimetric correlation coefficients in the rotation domain along the radar line of sight. The theoretical basis lies in that polarimetric correlation coefficients can reflect the different responses and can be enhanced at different levels for various land-cover types with suitable rotation angles in the rotation domain. In this vein, a polarimetric correlation coefficient optimization framework is established and new polarimetric features are extracted therein. Demonstration with multi-frequency (P-, L-, and C-bands) airborne synthetic aperture radar (AIRSAR) PolSAR data over crop areas validates that polarimetric correlation coefficients are crop dependent and the optimized polarimetric correlation coefficient parameters can better discriminate them. Then, a crop discrimination scheme is proposed using the derived polarimetric features. A flow chart for the optimal discrimination feature set selection and determination is provided and is validated by the real data with seven typical crop types. All these crop types are successfully discriminated for the P- and L-band data, whereas only two types of crops are slightly overlapped in the feature space for the C-band data. Experimental studies demonstrate the efficiency and potential of the established methodology. [ABSTRACT FROM AUTHOR]

This paper explores the use of full polarimetric synthetic aperture radar (PolSAR) images for tsunami damage investigation from the polarimetric viewpoint. The great tsunami induced by the earthquake of March 11th, 2011, which occurred beneath the Pacific off the northeastern coast of Japan, is adopted as the study case using the Advanced Land Observing Satellite/Phased Array type L-band Synthetic Aperture Radar multitemporal PolSAR images. The polarimetric scattering mechanism changes were quantitatively examined with model-based decomposition. It is clear that the observed reduction in the double-bounce scattering was due to a change into odd-bounce scattering, since a number of buildings were completely washed away, leaving relatively a rough surface. Polarization orientation (PO) angles in built-up areas are also investigated. After the tsunami, PO angle distributions from damaged areas spread to a wider range and fluctuated more strongly than those from the before-tsunami period. Two polarimetric indicators are proposed for damage level discrimination at the city block scale. One is the ratio of the dominant double-bounce scattering mechanism observed after-tsunami to that observed before-tsunami, which can directly reflect the amount of destroyed ground-wall structures in built-up areas. The second indicator is the standard deviation of the PO angle differences, which is used to interpret the homogeneity reduction of PO angles. Experimental results from after- and before-tsunami comparisons validate the efficiency of these indexes, since the built-up areas with different damage levels can be well discriminated. In addition, comparisons between before-tsunami pairs further confirm the stability of the two polarimetric indexes over a long temporal duration. These interesting results also demonstrate the importance of full polarimetric information for natural disaster assessment. [ABSTRACT FROM PUBLISHER]

Abstract: The putative anxiolytic activity of asiaticoside was examined in male mice by using a number of experimental paradigms of anxiety, with diazepam being as a positive anxiolytic control. In the elevated plus-maze test, diazepam (1 and 2 mg/kg) or asiaticoside (5 or 10 mg/kg) increased the percentage of entries into open arms and of time spent on open arms. In the light/dark test, as with 1 mg/kg diazepam, asiaticoside (10 and 20 mg/kg) increased the time spent in the light area and the movement in the light area without altering the total locomotor activity of the animals. In the hole-board test, asiaticoside at 10 mg/kg significantly increased head-dipping counts and duration as well as diazepam (0.3 mg/kg). Thus, these findings indicated that asiaticoside exhibited an anxiolytic-like effect. Further studies will be required to assess the generality of present findings to other species and behavioural paradigms. [Copyright &y& Elsevier]

Abstract: In our previous studies using an elevated plus-maze test in mice, taurine was shown to present an anxiolytic-like effect after single and repeated administration [Chen SW, Kong WX, Zhang YJ, Li YL, Mi XJ, Mu XS. Possible anxiolytic effects of taurine in the mouse elevated plus-maze. Life Sci 2004;75: 1503–11]. The aim of the present study was to investigate the anxiolytic and behavioral effects of taurine on rats in the open field, hole-board, and social interaction test compared to the positive control diazepam. Taurine (14, 42, and 126 mg/kg, i.p.) was administered 30 min before the tests. In the social interaction and hole-board tests, taurine (42 mg/kg) significantly increased social interaction time and the number and duration of head-dipping. In the open field test, taurine (126 mg/kg, i.p.) presented anxiolytic-like effects by increasing the number of center entries, time spent in the central area and the anti-thigmotactic score while having no effect on the locomotor activity. Results from these experiments suggest that taurine produces an anxiolytic-like effect in these animal models and may act as a modulator or anti-anxiety agent in the central nervous system. [Copyright &y& Elsevier]

Abstract: The present study was designed to investigate the putative anxiolytic-like effect of sinomenine in three experimental models of anxiety in male rats and mice. Use of the elevated plus-maze test revealed that sinomenine (20 and 40 mg/kg, p.o.) increased the percentage of open arm entries and diazepam (2 mg/kg, p.o.) increased the percentage of open arm entries, the percentage of time spent on open arms and total arm entries in mice. In the light/dark transition test, sinomenine (20 and 40 mg/kg, p.o.) increased time spent in the light area and diazepam (2 mg/kg, p.o.) increased time spent in the light area and the overall movements in mice. In the social interaction test, the sinomenine-treated animals significantly increased social interaction time in low light unfamiliar (7 mg/kg, p.o.) and high light unfamiliar conditions (7 and 14 mg/kg, p.o.) as well as diazepam (3 mg/kg, p.o.). Sinomenine (28 mg/kg, p.o.) can also decrease squares entered in rats in social interaction test under low light unfamiliar condition. In the open-field test, sinomenine (160 mg/kg) decreased squares entered in mice. Thus, these findings indicated that sinomenine exhibited anxiolytic-like effect. [Copyright &y& Elsevier]

Abstract: In our previous studies, we have demonstrated the anxiolytic effects of angelica essential oil in three anxiety models using mice. This study aimed to characterize the similar behavior effects of angelica essential oil in the social interaction test of anxiety and the hole-board test of exploration and locomotor activity in rats. These results indicate that angelica essential oil possessed a wide range of anxiolytic properties. In the social interaction test, angelica essential oil decreased aggressive behaviors at the doses of 21 and 42 mg/kg, while the doses of 21 and 42 mg/kg significantly increased social interaction time of the high light, unfamiliar test condition and 21 mg/kg could also prolong social interaction time of the high light, familiar test condition. In the hole-board test, angelica essential oil at 10.5 mg/kg significantly increased head-dipping counts and duration. Thus, our findings suggest the potential usefulness of angelica essential oil against various types of anxiety-related disorders and social failure. [Copyright &y& Elsevier]

Abstract: The present study in mice compared the putative anxiolytic-like effect of paeonol, a phenolic component from the root bark of Paeonia moutan, with the benzodiazepine diazepam in the elevated plus maze and the light/dark box-test. The comparison was also with regard to locomotor activity (open-field test) and myorelaxant potential (inclined plane test). As with 2 mg/kg diazepam, paeonol (at 17.5 mg/kg) increased the percentage of time spent on open arms in the elevated plus maze and increased the time spent in the light area of the light/dark box (at 8.75 and 17.5 mg/kg). Since paeonol, in contrast to diazepam, had no effect on either the number of squares entered in the open-field test or in the inclined plane test, its side-effect profile is considered as superior to the benzodiazepine. [Copyright &y& Elsevier]

The effects of angelica essential oil in three assays predictive of anxiolytic activity in male mice were studied, with diazepam as a positive anxiolytic control. In the elevated plus-maze test, compared to the positive control diazepam, angelica essential oil (30.0 mg/kg, PO) had a modest anxiolytic-like effect (increased the percentage of open-arm time and reduced the percent protected head dips). In the light/dark test, angelica essential oil (30.0 mg/kg) prolonged the time spent in the light area without altering the locomotor activity of the animals. In the stress-induced hyperthermia test, 60 and 70 min after drug administration, rectal temperature was measured twice, angelica essential oil at the dose of 30.0 mg/kg inhibited stress-induced hyperthermia. Thus, these findings indicate that angelica essential oil, as does diazepam, exhibits an anxiolytic-like effect. Further studies will be required to assess the generality of the present findings to other species and behavioural paradigms. [Copyright &y& Elsevier]

The effects of taurine, an inhibitory amino acid, on the behavior of male mice were examined in the elevated plus-maze test of anxiety. Acute taurine treatment (60 mg/kg, PO) significantly increased the percentage of time spent in the open arms. Moreover, when taurine was administered daily for seven days and the plus-maze test was conducted 40 minutes after the last administration, a significant increase of the percentage of time in the open arms was observed even at dose of 2.5 mg/kg, however the open arm entries and the total entries were unaffected at any dose tested. In order to get a comprehensive profile of drug action, detailed behavioral analyses were further exerted. Single administration of 60 mg/kg taurine can significantly reduce the total rears. The results suggest that taurine have some anxiolytic-like properties, although its effects seem more limited and are not consistent with those presented by classic anxiolytics, such as diazepam. [Copyright &y& Elsevier]

The putative anxiolytic activity of succinic acid was examined in male mice by using a number of experimental paradigms of anxiety and compared with that of the known anxiolytic compound diazepam. Use of the elevated plus-maze test revealed that diazepam (1.0, 2.0 and 4.0 mg/kg, PO) or succinic acid (3.0 or 6.0 mg/kg, PO) increased the percentage of entries into open arms and of time spent on open arms. In novel food consumption test, succinic acid (3.0, 6.0, and 12.0 mg/kg, IP) caused significant increases in food intake during 5 min when compared with the vehicle. In the stress-induced hyperthermia test, 40 min after drug administration rectal temperature was measured, succinic acid at dose of 1.5 mg/kg, inhibited stress-induced hyperthermia. Thus, these findings indicated that, in contrast with diazepam, succinic acid exhibits anxiolytic-like effect. [Copyright &y& Elsevier]

Based on the finite element analysis and the automatic modeling, the interconnect reliability for GaN monolithic microwave integrated circuit (MMIC) power amplifier (PA) with different transistor sizes, currents, and temperatures have been predicted effectively in this article. The modeling and computation are completed automatically based on the ANSYS Parametric Design Language (APDL) to study the electromigration (EM) failure of interconnect. By controlling the temperature, the current and the transistor size, the atomic flux divergence (AFD) of interconnect in different states for this PA has been obtained. It can be concluded that the increase of the temperature and the current, and the decrease of the transistor size may promote the EM failure. Furthermore, the sensitivity analysis for AFD of this model is performed too. Then, a feasible solution space can be obtained which can help the designer to get the reliability performance for any design requirement and the trade off decisions on the transistor size and the operation condition. This is the first study of interconnect reliability for a high power GaN MMIC PA, thus the interconnect reliability research for complex IC can be further explored. [ABSTRACT FROM AUTHOR]

The recognition of partially occluded targets is a difficult problem in the field of synthetic aperture radar (SAR) target recognition. To eliminate the effect of occlusion, the intuitive idea is to determine the exact location and the size of the occluded area. However, this is very difficult, even impossible in practice. In order to avoid this difficulty and to improve the recognition performance for the partially occluded target, a fusion strategy of the sparse representation (SR) model based on randomly erased images is proposed to recognize the partially occluded target. The proposed method randomly erases some areas many times in both the test samples and the training samples. The erased training samples in each erasure are used to sparsely represent the corresponding erased test sample. Finally, all the SR results are fused to recognize the test sample. The proposed method utilizes random erasure to eliminate the possible occluded region. In addition, this method uses the fusion strategy to overcome under-erasing of the occluded region and erroneous erasure of the unoccluded region. The key parameter of the proposed method is the erasure ratio only. Although the erasure is random, the recognition performance of the method is relatively stable. Therefore, the method can eliminate the influence of occlusion without determining the details of occlusion. The experimental results show that the proposed method is significantly better than the state-of-the-art methods in the case of occlusion. Additionally, the recognition performance of the proposed method is similar to some comparison methods in the case of no occlusion. [ABSTRACT FROM AUTHOR]

[Display omitted] • A fully space-confined TSCT-TADF emitter TRZ-STFMe is developed for organic electroluminescence. • The methyl substituent induces a compact donor–acceptor stacking to suppress structural change. • TRZ-STFMe shows a low activation energy for facilitating RISC process. • A TRZ-STFMe OLED shows a superior EQE of 29.6% with slight efficiency roll-off. The emerging through-space charge transfers (TSCT) emitters with thermally activated delayed fluorescence (TADF) have drawn increasing interest. However, the low luminescence efficiency and slow reverse intersystem crossing (RISC) always limit their device performances. A new molecular design strategy for TSCT-TADF emitters with a fully space-confined donor/acceptor conformation that integrates high luminescence efficiency and fast RISC is proposed herein. Two new TSCT-TADF emitters, TRZ-STFMe and TRZ-STFPh, are developed by introducing the methyl and phenyl substituents at the C2 of the rigid fluorene scaffold, respectively. The repulsive interaction between methyl and the acceptor induces a close and face-to-face donor–acceptor stacking to generate highly efficient TADF and suppress structural changes during the RISC process in TRZ-STFMe. In contrast, TRZ-STFPh shows relatively low luminescence efficiency and slow RISC because of its conformationally unstable phenyl substituent. With a high luminescence efficiency of 97 % and a significant RISC rate of 5.23 × 105 s−1, TRZ-STFMe demonstrates a high electroluminescence performance with a maximum external quantum efficiency (EQE) of 29.6 % and an EQE of 26.5 % at 1000 cd m−2. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel aromatic Schiff base-based polymeric phase change materials. • Safe, leak-free, and efficient thermal energy management. • Self-crosslinking of aromatic Schiff base for molecular firefighting. • Open a window for designing multifunctional leak-free phase change materials. Polymeric phase change materials (PCMs) have garnered enduring interest owing to no leakage and considerable latent heat in thermal management. However, the flammability, poor recyclability, and low energy storage density of typical polymeric PCMs have long-term constraint on their applications in sustainable energy. Herein, we fabricated a novel linear polymeric solid–solid PCM (HPPEG-PU) with facile recyclability, fire safety, and simultaneous high heat transition capacity via introducing aromatic Schiff base structure into the hard segment of HPPEG-PU and meanwhile using high-molecular-weight polyethylene glycol as energy-storage soft segment. HPPEG 8000 -PU achieved the latent heat of 131.1 J g−1, higher than the reported polymeric solid–solid PCMs, and realized thermal reprocessing at 80 ℃ and fire extinguishment once being ignited. Mechanisms for safe, leak-free, and highly efficient thermal energy storage/release were discussed deeply, in which aromatic Schiff base structure induced network confinement, crystallization, and self-crosslinking charring are highly responsible for shape stability, high thermal storage capacity, and fire safety, respectively. Based on the phase change characteristic of HPPEG-PU, thermosensitive imaging and convenient thermal management applications were developed in this work. Cunningly targeting aromatic Schiff base structure to polymeric PCMs may provide a promising route for safe, leak-free, and efficient thermal energy management. [ABSTRACT FROM AUTHOR]

• A bio-based PIMEPA@ATH were synthesized via a facile "self-assembly combine metal chelate-mediated complex" strategy only using water as the assembly media. • PIMEPA@ATH endowed EVA with excellent fire retardancy and largely reduced peak smoke production rate. • The tensile properties of EVA/PIMEPA@ATH were improved compared with the EVA/PIMEPA control. • The flame-retardant mechanism of PIMEPA@ATH was demonstrated in detail. A bio-based intumescent flame retardant (denoted as PIMEPA@ATH) was synthesized via metal chelation using water as the media. The PIMEPA@ATH complex aggregations was used to improve the flame retardancy of ethylene-vinyl acetate copolymer (EVA) by synergistic combination of piperazine-melamine phytate complex (denoted as PIMEPA) and aluminum hydroxide (ATH). During combustion, the in-situ growth of crystalline aluminum metaphosphate arising from PIMEPA@ATH helped to cast more compact protective barriers containing metal ions and aromatic rings. The results showed that the EVA sample containing 30 wt% PIMEPA@ATH achieved the UL-94 V0 rating without dripping in the vertical burning test and a reduction of 79% in peak heat release rate and 58% reduced peak smoke production rate in the cone calorimeter test. Moreover, the tensile properties of EVA/PIMEPA@ATH were improved compared with the EVA/PIMEPA control. Better char formation and improved interfacial adhesion were primarily responsible for the enhancements in flame retardancy and mechanical performance. This work demonstrated the flame-retardant mechanism of PIMEPA@ATH, and explored a facile and green "chelate-mediated" strategy for synthesis of bio-based and ATH chelate-mediated intumescent flame retardant. [Display omitted] [ABSTRACT FROM AUTHOR]