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As vehicle speed is fast and on board units' (OBUs) computing power, storage space, bandwidth and other resources are very limited, the efficiency of message transmission in vehicular ad hoc network is of great concern. Certificate‐based aggregate signature scheme provides a way to combine numerous signatures into one short signature. The authors propose a certificate‐based aggregate signature scheme for vehicular ad hoc networks. In this study, the authors prove that the proposed scheme is secure against forgery attack in the random oracle model and under the computational Diffie–Hellman problem. It is efficient and suitable for vehicular ad hoc networks.

Developing electrochromic materials with energy-saving (i.e., low driving voltage) and long-life (i.e., high switching stability) properties is highly desirable with respect to practical application. In this work, we report the synthesis of two N,N′-di(4-pyridyl)-1,4,5,8-naphthalene diimide derivatives (DPNDIs), (Me2DPNDI)·(2I) and (benzyl2DPNDI)·(2Br), and the characterization of their electrochemical and electrochromic properties. Both DPNDIs showed two quasi-reversible redox couples in the cyclic voltammograms with cathodic peak potentials of approximately −0.30 and −0.70 V vs. Ag/Ag+. The electrochromic devices based on ((Me2DPNDI)·(2I) and (benzyl2DPNDI)·(2Br)) gave a colored state of dark orange and orange, respectively, which are colored states that have rarely been reported, and both DPNDIs had a low onset bias of −0.7 V and good switching stabilities (the change in optical contrast after 7200 s of

Six novel electrochromic materials, 4,4′,4′′-nitrilotribenzoates (NTBAs, a–f), with donor–acceptor structure, were designed by combining cathodically electrochromic benzoates as a color-tuning unit and anodically electrochromic triphenylamine as a fluorescence-quenching unit to achieve multi-electrochromism and electrofluorochromism. The stereochemistry of the NTBAs was investigated by single-crystal X-ray diffraction. The NTBAs showed a strong blue emission in N,N-dimethylformamide. When the NTBAs were introduced into electrochromic devices (ECDs), all six ECDs showed multicolored electrochromism. All six ECDs displayed electrofluorochromic behavior, which was possibly caused by the monocationic radical formed from the oxidation of the triphenylamine center. The ester substituents markedly influenced the colored states, switching cyclability, coloration efficiency, and electrofluorochromic properties. The compounds with saturated alkyl substituents (a–c) showed three colored states, namely yellow (at ±2.8 V), light red (at ±3.0 V), and orange red (at ±3.6 V), relatively better cyclability, high coloration efficiency (>220 cm2 C−1), and good electrofluorochromic properties. The compound with the shortest chain length (a) performed best. The compound with an unsaturated alkyl substituent (d) showed poor electrochromic and electrofluorochromic properties. The compounds with aryl substituents (e and f) showed three colored states, namely yellow (at ±2.6 V), purple (at ±3.0 V), and claret (at ±3.6 V), moderate coloration efficiency (ca. 200 cm2 C−1), and good electrofluorochromic properties. The cyclability was markedly improved when the aryl substituents contained an electron-donating group.

Ten tripod-shaped electrochromic materials (compound 1–10) were designed and synthesized by esterification of 4,4′,4″-s-triazine-2,4,6-triyl-tribenzoic acid with different alcohols and phenols. These materials have a 2,4,6-triphenyl-1,3,5-triazine core and three ester side arms, forming an electron donor–π-acceptor structure. The electrochemical and optical properties of 1–10 were characterized by cyclic voltammetry and ultraviolet–visible spectroelectrochemistry. The conjugated structure of 1–10 markedly influenced their electrochemical properties. Electrochromic devices containing some of these compounds (1, 2, 4, 5, and 10) displayed intense color changes, fast switching times ( 60%), good switching stability, high optical density (>1.0), and high coloring efficiency (>1000 cm2 C−1). The colored state of these devices strongly depended on the conjugated structure of the tripod-shaped component. Short chain lengths (compounds 1 and 2) and electron-donating groups (compounds 4, 5, 8, and 10) were beneficial to electrochromic properties, whereas a longer chain length (compound 3) and electron-withdrawing groups (compounds 6 and 9) adversely affected electrochromic properties.

The design and synthesis of broad absorption electrochromic materials (ECMs) that modulate visible and near infrared light are important for energy-saving smart windows. Most studies on broad absorption ECMs have focused on transition metal oxides, organic polymers and small organic molecules based on triarylamines, while studies on viologen analogues are scarce. In the current study, two tetra-substituted viologen analogues 4,4′,4″,4‴-(benzene-1,2,4,5-tetrayl)- tetrakis(1-butylpyridin-1-ium) (BTTBP) and 1,1,2,2-tetrakis(4-(1-butyl-pyridin-4-yl)- phenyl)ethane (TBPPE) were prepared by introducing benzene and tetraphenylethylene with large conjugation degrees as parent moieties. Compared with the conventional viologen 1,1′-dibutyl-(4,4′-bipyridine)-1,1′-diium without a conjugated parent, BTTBP and TBPPE exhibited high electrochromic performance and broad absorption to the near infrared region. TBPPE in particular exhibited excellent broad absorption electrochromic behavior with high optical contrast (63% at 733 nm and 46% at 997 nm), distinct color change (pale yellow to yellow-green to black-green), good cycling stability (attenuation in optical contrast of 1% after 1000 cycles at 733 nm) and excellent coloration efficiency (251 cm2/C) in the near infrared region. These findings provide a strategy for designing high-performance cathode broad absorption ECMs and a promising candidate for energy-saving smart windows.

In this study, a series of novel star-shaped monosubstituted 2,6-diphenyl-4,4′-bipyridinium salts with various alkyl, alkenyl, and aryl groups were designed and synthesized, and their electrochemical, electro-optical, and electrochromic properties were investigated. The electrochromic properties such as different colored states (sky blue versus purple), reasonable contrast, coloration efficiency, and, in particular, the switching stabilities of electrochromic devices based on star-shaped monosubstituted 2,6-diphenyl-4,4′-bipyridinium salts were better than those of devices based on linear monosubstituted pyridinium salts. All the compounds with alkyl, alkenyl, and aryl groups showed good switching stability and the change in the optical contrast after 1000 cycles was small (

In this work, a series of dual functional materials, 4,4′,4″,4‴-(ethene-1,1,2,2-tetrayl)tetrabenzoates (ETBAs), were developed with an aggregation-induced emission (AIE) luminogenic center (tetraphenylethylene) and electrochromically active moieties (benzoates). The highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels of the ETBAs were determined via density functional theory calculations. The fluorescent, electrochemical, and electrochromic performances of the ETBAs were characterized via fluorescence spectroscopy, cyclic voltammetry, UV–Vis spectroscopy, and chronoamperometry. All the ETBAs demonstrated an AIE effect in water/N-methyl pyrrolidone. The ETBAs underwent a quasi-reversible reduction-oxidation. Electrochromic devices based on the ETBAs exhibited a significant color change from a transparent bleached state to a colored blue state, high optical contrast (ca. 80%), and large coloration efficiency. The used substituents markedly influenced the cyclability and response time, and compounds with a larger conjugation degree had lower energy gap values and faster response time. Compound c with a longer alkyl chain length had the best performance with regards to coloration efficiency and cyclability. In summary, this work demonstrated a strategy for the design of novel high-performance ECMs and could extend the applications of such multi-functional materials.

The application of photoresponsive surface molecularly imprinted polymers based on azobenzene is limited by the UV light source required and their poor water solubility. Reducing the phototoxicity and solvent toxicity of the polymers therefore presents a challenge. In this work, an NIR-light-responsive surface molecularly imprinted polymer was fabricated by atom transfer radical polymerization using up-conversion nanoparticles as the core, a hydrophilic green-light-responsive azobenzene derivative as the functional monomer, and a drug as the template. The up-conversion nanoparticles core emitted green fluorescence in the range of 520–550 nm upon NIR irradiation (980 nm, 5 W cm−2), which was absorbed by the azobenzene containing molecularly imprinted polymers layer on the up-conversion nanoparticles surface. This caused the azobenzene chromophores to undergo trans→cis isomerization in phosphate buffered solution (pH = 7.4), thus resulting in NIR-light-induced drug release. The up-conversion fluorescence spectra were used to study the interaction mechanism between the azobenzene monomer and NIR light. Compared with structural analogues of the template (antifebrin and phenacetin), the NIR-light-responsive surface molecularly imprinted polymer showed excellent specificity of recognition for the template drug (paracetamol). The maximum adsorption capacity of the NIR-light-responsive surface molecularly imprinted polymer for loading of paracetamol was 16.80 μmol g−1. The NIR-light-responsive surface molecularly imprinted polymer was applied for NIR-light-induced paracetamol release in phosphate buffered solution (pH = 7.4) through porcine tissue. This work demonstrates the potential of drug delivery systems based on molecularly imprinted polymers for application in deep tissue delivery.

In this study, the electrochromic behavior of benzonitrile compounds were investigated. For this, a series of benzonitrile compounds with different chemical structures were synthesized and their electrochemical properties were investigated by cyclic voltammetry. Electrochromic behavior of the benzonitrile derivatives were also investigated by constructing sandwich type electrochromic devices and recording the changes in the UV–vis spectra as a function of applied potential. The compounds exhibited excellent electrochromic properties such as a high optical contrast, low driving voltage, good switching stability, high coloration efficiency, and a fast response time. All five compounds had different colors (orange, yellow-green, reddish-brown, green, blue) and driving voltages that were highly dependent on their chemical structures. The results indicate that benzonitriles are good electrochromic materials and should be of interest for applications such as electrochromic smart windows, information displays, and optical storage devices.

To study the therapeutic effects and mechanism of saikosaponin-d (SSd) in mice with bleomycin (BLM)-induced pulmonary fibrosis.According to the random number table, 180 mice were randomly divided into 5 groups. Four groups were pulmonary fibrosis models. Fibrosis model mice were established by intratracheal injection of bleomycin (5 mgxkg(-1)). They were BLM, DXM, SSd and SSd + DXM groups (n = 40 each). At 1 hour post-modeling, DXM, SSd and SSd + DXM groups were injected ip with dexamethasone (DXM, 5 mgxkg(-1)xd(-1), 0.1 ml), SSd (1.8 mgxkg(-1)xd(-1), 0.18 ml), DXM + SSd (0.28 ml) respectively qd until Day 28. BLM group was similarly dosed with normal saline. In addition, a normal control group (NC group, n = 20) treated likewise. The mice were anesthetized and sacrificed at Days 3, 7, 14, 28 for harvests of serum and lung tissue samples. The conventional histopathological changes of lung tissue were observed. Except for NC group, modeling groups of mice were used to observe the natural survival rate. Such indices as superoxide dismutase (SOD) and malonaldehyde (MDA) were examined both in lung tissue and serum samples. And hydroxyproline (HYP) was tested only in lung tissue.SSd could markedly increase the survival rate (80.0% in SSd and SSd + DXM groups vs 50.0% in BLM group, P0.05) and reduce alveolitis and fibrosis in mice. In comparison with BLM group, the levels of HYP of three treatment groups (DXM, SSd and SSd + DXM) in lung tissue was significantly lower (P0.05) at Days 14 and 28. The levels of MDA both in serum and lung tissue were significantly lower at Days 3, 7 and 14 (P0.05). The serum level of SOD was significantly higher at Days 3, 7 and 14 while the level of SOD in lung tissue was significantly higher at Days 3 and 7 (P0.05, P0.01).SSd has marked therapeutic effects upon bleomycin-induced pulmonary fibrosis in mice. And the mechanism may be associated with its anti-lipid peroxidation effect.