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Steam reforming is an effective measure for biomass tar elimination as well as H2-rich syngas (H2 + CO) production. However, the granular or powdery Ni-based catalysts are prone to deactivation, which is caused by inappropriate mass transfer and clogging of catalyst bed. Herein, monolithic wood carbon (WC) with low-tortuosity microchannels is armed with a carbon-coated mesoporous nickel-silica nanocomposite (Ni-SiO2@C) layer via an evaporation-induced self-assembly and calcination procedure for toluene (tar model compound) steam reforming. The quality of the Ni-SiO2@C layer growing on the surface of WC microchannel is affected by the molar ratios of Si/Ni feed. A uniform thin-layer coverage is obtained on the Ni-15SiO2@C/WC (Si/Ni = 15) catalyst, where highly dispersed Ni nanoparticles (average size of 6.6 nm) with appropriate metal-support interaction and remarkable mechanical strength are achieved. The mass transfer, coke resistance, and hydrothermal stability of the Ni-15SiO2@C/WC catalyst were significantly improved by the multilevel structure assembled from the WC microchannels and the secondary ordered SiO2 mesopores. A stable toluene conversion over 97% with an H2 yield of 135 μmol/min was obtained at 600 °C on the Ni-15SiO2@C/WC catalyst. This work opens a new window for facilely constructing high-performance wood carbon-based monolithic tar reforming catalyst.

With the formation of mesa-like cells at their surfaces, LiNbO3 thin films are useful for integrating high-density domain wall memory. However, the material is too hard and inert to etch the cells with inclined side edges that help to diminish polarization retention. Moreover, etching could damage the ferroelectricity of the film. To overcome these drawbacks in forming memory cells directly, we developed a technique to deposit two gapped electrodes in the film surface, without needing to etch the film. While applying an in-plane write voltage above a coercive voltage, the domain within the gap is reversibly switched along with the creation/erasure of conducting domain walls against the peripheral unswitched domain. This technique enables "on"/"off" current read of the written information. Unfortunately, the switched domain within the gap generally has poor retention and a weak wall current arises from the presence of a strong depolarization field. To overcome this problem, we fabricated a type of embedded electrode that diffuses thickness-wise into the LiNbO3 thin film to form a parallel-plate-like structure to screen the depolarization field. The switched domains now had good retention and carry large wall currents. Alternatively, without the embedded electrodes, the switched domains within the cells can be stabilized with increasing gap distance above a critical length of 320 nm. The two methods foreshadow the possibility in the future to fabricate damage-free LiNbO3 memory cells without etching.

Hydrophobic Mg(OH)2/calcium myristate (Ca[CH3(CH2)12COO]2, CaMS) and Mg(OH)2/magnesium myristate (Mg[CH3(CH2)12COO]2, MgMS) composite coatings were prepared on the alkali-treated AZ31 substrates via both electrodeposition and dipping methods. The morphologies, compositions, and constitutes of the coatings were investigated by using field-emission scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectrometry (FTIR) together with X-ray diffractometer (XRD). Furthermore, electrochemical (polarization and impedance spectroscopy) and hydrogen evolution tests were applied to evaluate the corrosion resistance. The wettability and adhesive strength of the composite coatings were characterized through water static contact angle (CA), sliding angle (SA), and nano-scratch tests. Results indicated that the better super-hydrophobicity, corrosion resistance, and adhesion were achieved via an electrodeposited process. The corrosion current density (icorr) and hydrogen evolution rate (HER) of the electrodeposited coating were three and one orders of magnitude smaller than the substrate, implying a significantly improved corrosion resistance. This scenario was ascribed to the super-hydrophobicity of electrodeposited composite coating with a contact angle (CA) and slide angle (SA) of 159.2° ± 0.8° and 5.2° ± 0.8°, respectively. However, the dipped composite coating was adverse to the improvement of corrosion resistance and adhesion due to the dissolution of the underlying Mg(OH)2 layer and smooth surface with less organic fatty acid salt (MgMS)

Dual-comb spectroscopy (DCS) has emerged as an important new technique for high-resolution molecular spectroscopy. However, this powerful tool has not been widely utilized in combustion diagnostics...

In this study, one novel WC/Ni flexible cloth coatings were prepared to enhance the abrasion and erosion resistances and meanwhile to accommodate the complicated component surfaces. Neither precipitation of WC particle nor pores or cracks were detected in the coating. The scarification extent of WC particle decreased with the increase in the WC content. With the abrasion mechanism of three body abrasive wear, the WC/Ni coating with 59.8 wt.% WC (WC/Ni-59.8 wt.%) showed the best abrasion resistance with the wear rate of 0.3% of 304 stainless steel. At 30° of impact angle, the WC/Ni-59.8 wt. % exhibited a superior erosion resistance to that of WC coating developed by high velocity oxygen fuel (HVOF). The application potential of WC/Ni flexible cloth coating for the commercial components was testified by developing the coating on a ball valve disc.

To enhance durability and adhesion of superhydrophobic surface, an integrated superhydrophobic calcium myristate (Ca[CH3(CH2)12COO]2) coating with excellent corrosion resistance was fabricated on AZ31 magnesium (Mg) alloy via one-step electrodeposition process. Field-emission scanning electron microscopy, Fourier transform infrared spectrometry and X-ray photoelectron spectroscopy as well as X-ray diffraction were employed to investigate the surface characteristics (morphology, composition and structure) of the coatings. Hydrophobicity of the coating was evaluated by means of contact and sliding angles. Additionally, potentiodynamic polarization, electrochemical impedance spectroscopy and hydrogen evolution tests were conducted to characterize the corrosion resistance. Results indicated that the coating exhibited super-hydrophobicity with large static water contact angle (CA) and small sliding angle of 155.2° ± 1.5° and 6.0° ± 0.5°, respectively, owing to spherical rough structure and low surface energy (7.01 mJ m−2). The average hydrogen evolution rate (HERa) and corrosion current density (icorr) of the coated sample were 5.3 μL cm−2 h−1 and 5.60 × 10−9 A cm−2, about one and four orders of magnitude lower than that of AZ31 substrate, respectively, implying the excellent corrosion resistance. The CA of the coating remained 155.6° ± 0.9° after soaking for 13 days, showing the super-hydrophobicity and stability of the coating. Simultaneously, the large critical load (5004 mN) for the coating designated the outstanding adhesion to the substrate by nano-scratch test.

Distributed sensing plays an important role in many industrial applications. Sensor arrays consisting of identical ultraweak fiber Bragg gratings can be applied to such scenarios by monitoring the optical spectral response of the sensors. Yet, the spatial resolution, the sampling speed, and the supported number of sensors in the array are mostly determined by the interrogation scheme. While dual-optical frequency comb techniques had been successfully demonstrated as a high-resolution spectroscopic technique in metrology, it had been beyond the reach of industrial sensing applications because of its high complexity and costs. It is proposed and demonstrated here that, enabled by a simple fiber-optic, dual-comb spectroscopy setup consisting of a fiber laser without frequency stabilization, interrogation of an ultraweak fiber sensor array can be realized. High spatial and spectral resolution as well as kilohertz interrogation speed is achieved in both static and dynamic measurements. It is expected that our depth-resolved dual-comb scheme can measure hundreds of sensors response in less than 1 ms. It is also flexible to deal with targets closely spaced or farther apart from each other. This shows the potential of applying dual-comb spectroscopy to more and more industrial application areas.

A number of industrial and biomedical fields, such as hydraulic fracturing balls for gas and petroleum exploitation and implant materials, require Mg alloys with rapid dissolution. An iron-bearing phosphate chemical conversion (PCC) coating with self-catalytic degradation function was fabricated on the Mg alloy AZ31. Surface morphologies, chemical compositions and degradation behaviors of the PCC coating were investigated through FE-SEM, XPS, XRD, FTIR, electrochemical and hydrogen evolution tests. Results indicated that the PCC coating was characterized by iron, its phosphates and hydroxides, amorphous Mg(OH)2 and Mg3-n(HnPO4)2. The self-catalytic degradation effects were predominately concerned with the Fe concentration, chemical composition and microstructure of the PCC coating, which were ascribed to the galvanic corrosion between Fe in the PCC coating and the Mg substrate. The coating with higher Fe content and porous microstructure exhibited a higher degradation rate than that of the AZ31 substrate, while the coating with a trace of Fe and compact surface disclosed a slightly enhanced corrosion resistance for the AZ31 substrate.

Titanium (Ti) has achieved extensive applications due to its excellent biocompatibility and mechanical properties. Plasma can enhance surface hydrophilia of Ti with decreased carbon contamination. The traditional conditions using a single gas plasma was for longer treatment time and more prone to being contaminated. We designed and developed novel and universal apparatus and methods with a special clamping device of non-thermal atmospheric plasma (NTAP) treatment using mixed gas for Ti surface activation. We systematically and quantitatively investigated the effective effects of NTAP-Ti. The surface water contact angle decreased by 100%, the carbon content decreased by 80% and oxygen content increased by 50% in the novel NTAP-Ti surfaces. NTAP treatment accelerated the attachment, spread, proliferation, osteogenic differentiation and mineralization of MC3T3-E1 mouse preosteoblasts in vitro. The percentage of bone-to-implant contact increased by 25–40%, and the osteoclasts and bone resorption were suppressed by 50% in NTAP-Ti in vivo. In conclusion, NTAP-Ti substantially enhanced the physical and biological effects and integration with bone. The novel and universal apparatus and methods with a special clamping device using gas mixtures are promising for implant activation by swiftly and effectively changing the Ti surface to a hydrophilic one to enhance dental and orthopedic applications.

We fabricate a metal-organic framework (MOF) saturable absorber (SA) based on a microfiber. Nonlinear optical absorption of the MOF SA is characterized systematically. The modulation depth is found to be 6.57% and 14.25% at 1.5 and 2 μm spectral ranges, respectively. We report ultrashort pulse generation in both Er- and Tm-doped fiber lasers by using the same microfiber-based MOF SA, operating at 384 fs and 1.3 ps pulse duration at 1563 nm and 1882 nm, respectively. To the best of our knowledge, this is the first report of a MOF-based fiber laser at near infrared spectral ranges. Our findings validate the applicability of MOFs as a broadband SA in ultrafast photonics.

Black phosphorus (BP) attracts huge interest in photonic and optoelectronic applications ranging from passive switch for ultrafast lasers to photodetectors. However, the instability of chemically unfunctionalized BP in ambient environment due to oxygen and moisture remains a critical barrier to its potential applications. Here, the parylene-C layer was used to protect inkjet-printed BP-saturable absorbers (BP-SA), and the efficacy of this passivation layer was demonstrated on the stable and continuous operation of inkjet-printed BP-SA in harsh environmental conditions. BP-SA was integrated in an erbium-doped ring laser cavity and immersed in water at ~60°C during operation for investigation. Mode-locked pulses at ~1567.3 nm with ~538 fs pulse width remained stable for >200 h. The standard deviation of spectral width, central wavelength, and pulse width were 0.0248 nm, 0.0387 nm, and 2.3 fs, respectively, in this period, underscoring the extreme stability of BP-SA against high temperature and humidity. This approach could enable the exploitation of BP-based devices for photonic applications when operating under adverse environmental conditions.

Improving proton conductivity is of great importance for the further application of metal–organic frameworks (MOFs) or metal–organic coordination polymers (MOCPs) in proton exchange membrane fuel cells. In this paper, we proposed a new approach to increase proton conductivities in MOCPs coming from organic ligands, e.g. coordination inducement and MOCP–cocrystal composite formation strategies, which is based on the potential function of organic ligands. By employing the approach, we have successfully synthesized and characterized three crystalline compounds, PPA (1), [Cu(PPA)I] (2) and [Co(PPA)2(BDC)(H2O)2·(PPA)2(H2BDC)2(H2O)] (3) (PPA = 4-(3-pyridinyl)-2-amino pyrimidine, H2BDC = 1,4-benzenedicarboxylic acid). These compounds show high water stabilities and different proton conducting behaviours, especially compound 3 with a proton conductivity of 2.29 × 10−4 S cm−1 at 325 K and ∼97% RH, which is higher than or comparable to those of some reported compounds. More importantly, a persistent increase in proton conductivity is observed from 1 to 3, which is about one order of magnitude. Furthermore, single crystal analyses show that coordination and hydrogen-bonding interactions play a crucial role in improving proton-conductive properties for these compounds. The study reveals that it is practical to boost the proton conductivity of crystal materials by means of their intrinsic merits and the strategy of molecular design.

In this study, nanosheet g–C3N4–H2 was prepared by thermal exfoliation of bulk g-C3N4 under hydrogen. A series of Ru/g–C3N4–H2 catalysts with Ru species supported on the nanosheet g–C3N4–H2 were synthesized via ultrasonic assisted impregnation-deposition method. Ultrafine Ru nanoparticles (3N4–H2. Strong interaction due to Ru-Nx coordination facilitated the uniform distribution of Ru species. Meanwhile, the involvement of surface basicity derived from abundant nitrogen sites was favourable for enhancing the selective hydrogenation performance of bi-benzene ring, i.e. almost complete 4,4′-diaminodiphenylmethane (MDA) conversion and >99% 4,4′-diaminodicyclohexylmethane selectivity, corresponding to a reaction activity of 35.7 molMDA molRu−1h−1. Moreover, the reaction activity of catalyst in the fifth run was 36.5 molMDA molRu−1h−1, which was comparable with that of the fresh one. The computational results showed that g-C3N4 as support was favorable for adsorption and dissociation of H2 molecules. Moreover, the substrate scope can be successfully expanded to a variety of other aromatic diamines. Therefore, this work provides an efficient and green catalyst system for selective hydrogenation of aromatic diamines.

It has been shown that an arginine-glycine-aspartic acid (RGD) modified pH-triggered delivery system for the urokinase-type plasminogen activator (uPA) is resistant to enzymatic degradation and improves thrombolytic ability in vitro. Herein, we aimed to compare the thrombolytic efficacies of uPA-oxidized dextran (Oxd)-RGD and uPA using a rat model of middle cerebral ischemia occlusion (MCAO) in vivo. We found that the uPA-Oxd conjugates delayed the release of active uPA after MCAO. Thus, the rats treated with uPA-Oxd-RGD showed significantly decreased neurological deficits and infarct volume compared with those of the rats treated with uPA alone after MCAO. Furthermore, the administration of uPA-Oxd-RGD attenuated blood–brain barrier disruption and downregulated matrix metalloproteinase expression while upregulating the expression of tight junction proteins. In addition, uPA-Oxd-RGD inhibited apoptosis by suppressing pro-apoptotic caspase expression. These results suggest that the administration of uPA-Oxd-RGD is a more effective intervention in an MCAO model than uPA alone and that the pH changes in the brain tissue after an ischemic stroke may be a novel thrombolytic target.

Purpose In order to promote osseointegration and shorten the healing time after dental implant operations, this study was conducted to develop a chair-side plasma treatment system in which Ti implants were used as a coaxial internal electrode to rapidly enhance their surface hydrophilicity. Methods Surface hydrophilicity was evaluated by measurement of the water contact angle and the defined wetting time. Changes in temperature and chemical composition were analyzed using infrared thermal imaging and X-ray photoelectron spectroscopy (XPS), respectively. The biocompatibility of the treated implants was examined in an animal experiment. Results A marked improvement of hydrophilicity was demonstrated by a decrease in the water contact angle of the treated implant to 0° and wetting of the whole surface within 3 s of water contact. The Ti implant hydrophilization mechanism was explained as a decrease in the degree of hydrocarbon contamination. The surface temperature of the treated implant was close to that of the human body, and good osseointegration was observed in the in vivo experiment. Conclusion The plasma treatment system developed here is a promising chair-side procedure for rapidly enhancing the surface hydrophilicity of Ti implants in clinical operations without any need to consider the degradation of hydrophilicity caused by long-term storage.

The magnetization orientation dependence of Gilbert damping and ultrafast demagnetization were investigated in single-crystalline ${\mathrm{Co}}_{50}{\mathrm{Fe}}_{50}$ films grown on a MgO(100) substrate by the time-resolved magneto-optical Kerr effect technique. The intrinsic Gilbert damping coefficient extracted from the time evolution of magnetization precessions shows a remarkably large anisotropy with a ratio of more than 300% for magnetization orientations along the $\ensuremath{\langle}100\ensuremath{\rangle}$ and $\ensuremath{\langle}110\ensuremath{\rangle}$ axes. Such a large anisotropy of Gilbert damping persists to high frequencies up to $50\phantom{\rule{4pt}{0ex}}\mathrm{GHz}$, where the effect of two-magnon scattering is suppressed. In contrast to the anisotropic Gilbert damping, the ultrafast demagnetization time and ratio for different in-plane magnetization orientations are nearly isotropic with the magnetization orientation. Although anisotropic Gilbert damping can be explained by the variation of spin-orbit coupling with the magnetization orientations, our results demonstrate that the role of spin-orbit coupling in the high nonequilibrium state after ultrafast laser excitation is isotropic in driving ultrafast spin-flip processes.

Hypothesis Janus nanosheets, which have two surfaces of different functionalities, exhibit unique interfacial properties. In this work, we propose a facile and scalable technique for preparation of silica-based Janus nanosheets, which is based on formation of high internal phase water-in-oil emulsions stabilized solely by alkyl-substituted polyethoxysiloxanes due to their hydrolysis-induced interfacial activity. Experiments Janus nanosheets are then obtained by crushing the silica foams converted from such emulsions. The morphology of Janus nanosheets is investigated by field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The chemical structure of functional silica materials is characterized by Fourier transform infrared spectroscopy (FT-IR). The asymmetric structure of silica nanosheets is observed by confocal laser scanning microscopy. Findings The resulting nanosheets have a rough hydrophobic surface and a smooth hydrophilic one, and are capable of stabilizing Pickering oil-in-water emulsions. Remarkably, pH-responsiveness of emulsions can be attained using the nanosheets whose hydrophilic surface is substituted with amino groups. Fast oil–water separation is achieved by the Janus nanosheets, which has been demonstrated by the nanosheets with a polystyrene-coated hydrophobic surface. This work paves a new avenue for large-scale production of functional silica-based Janus nanosheets suitable for numerous promising applications.

Development of simple and efficient red emissive luminogens is desirable yet challenging for optoelectronic devices due to the limited molecular design and the difficulties of synthesis. Red emitting molecules possess large π‐conjugated systems, which permit quenching in the solid state due to π–π stacking and are detrimental to the performance of devices. Furthermore, traditional red emitters usually exhibit emission far from pure red in the standard red, green, and blue (sRGB) gamut. Herein, two red luminogens, DCMa and DCIs, with aggregation‐induced emission (AIE) characteristics based on simple donor–acceptor (D–A) structures are explored. They show high fluorescence quantum yields (QYs) of 13.2% and 7.8% in the film state. Efficient nondoped solution‐processed organic light emitting diodes (OLEDs) with a configuration of indium tin oxide (ITO)/poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS)/poly[(9,9‐dioctylfluorenyl‐2,7‐diyl)‐co‐(4,40‐(N‐(4‐sec‐butylphenyl)diphenylamine)] (TFB)/DCMa or DCIs/(1,3,5‐tris(2‐N‐phenylbenzimidazolyl)benzene) (TPBi)/LiF/Al are fabricated, which emit red electroluminescence at 652 and 711 nm, respectively. Furthermore, they exhibit International Commission on Illumination (CIE) coordinates of (0.63, 0.36) and (0.64, 0.35), respectively, which are close to the value of the primary red color (0.63, 0.34) according to the digital television standard. These results of small molecules DCMa and DCIs suggest future methods for designing new red emitters for nondoped solution‐processed OLEDs.

In this chapter simulation and analysis of single and multiple slot waveguide structures had been carried out using FDTD algorithm. It was found that multiple slot structures not only increase the power confinement factor in low index slot regions but can also be utilized in forming sensor mechanisms. Other than traditional SOI slot optical waveguides, low contrast (glass and air based) slot optical waveguides with comparable power confinement factor had been proposed. Later the low contrast double slot optical waveguide structure had been utilized in forming cantilever based sensing mechanisms. Light confinement inside low contrast double slot structure has been explored and found comparable to SOI based slot optical waveguide structure. Based on cantilever type movement of low index slots of proposed low contrast double slot structure a simple and easy to build optomechanical sensor has been proposed. Single frequency continuous wave Gaussian pulse source has been used in simulations which is readily available. It could be most probable candidate for use in temperature, pressure and surface smoothness sensing.

Ag₃PO₄/sulfur-doped g-C₃N₄ heterojunctions were fabricated by the means of a facile calcination and co-precipitation method. Structural characterization suggested that Ag₃PO₄ was successfully loaded onto sulfur-doped g-C₃N₄. The absorption band edges of sulfur-doped g-C₃N₄ were shifted to the longer wavelength in comparison with bulk g-C₃N₄. The Ag₃PO₄/sulfur-doped g-C₃N₄ heterojunctions manifested substantially higher visible-light photocatalytic performance as compared with Ag₃PO₄/bulk g-C₃N₄. Photoluminescence spectra suggested that the stable Ag₃PO₄/SGCN heterojunctions could effectively address the electron-hole recombination rate, together with remarkably enhancing the photocatalytic activity. The enhancement of light absorption and better dispersion in Ag₃PO₄/sulfur-doped g-C₃N₄ provide more migration channels, together with posing crucial responsibility for the enhanced photocatalytic performance.

Au25(C6H14S)18 - icosahedron and [Au25(PPh)10(C6H14S)5Cl2]2+ bi-icosahedron clusters were synthesized. Ligand exchange reactions were carried out with a new coumarin-derived fluorophore (Cou-SH) to label both clusters. Labeled and unlabeled Au25 were compared and the changes in the electronic structure were determined. The labeled clusters showed marked changes in electronic states, as evidenced by the quenching in the UV region and enhancement in the near infrared. The quantum yield from Cou-SH decreased and the quantum yield from the labeled Au25 increased. Second, the authors observed changes in the electrochemical band gap.

The synthesis of a new azobenzene (azo)-containing main-chain crystalline polymer with reactive secondary amino groups in its backbone and photodeformation behaviors of its supramolecular hydrogen-bonded fibers are described. This main-chain azo polymer (namely Azo-MP6) was prepared via first the synthesis of a diacrylate-type azo monomer and its subsequent Michael addition copolymerization with trans-1,4-cyclohexanediamine under a mild reaction condition. Azo-MP6 was found to have a linear main-chain chemical structure instead of a branched one, as verified by comparing its 1H-NMR spectrum with that of the azo polymer prepared via the polymer analogous reaction of Azo-MP6 with acetic anhydride. The thermal stability, phase transition behavior, and photoresponsivity of Azo-MP6 were characterized with TGA, DSC, POM, XRD, and UV-Vis spectroscopy. The experimental results revealed that it had good thermal stability, low glass transition temperature, broad crystalline phase temperature range, and highly reversible photoresponsivity. Physically crosslinked supramolecular hydrogen-bonded fibers with good mechanical properties and a high alignment order of azo mesogens were readily fabricated from Azo-MP6 by using the simple melt spinning method, and they could show " reversible” photoinduced bending under the same UV light irradiation and good anti-fatigue properties.

α-Fe2O3/porous g-C3N4 (α-Fe2O3/PCN) photocatalysts were fabricated via a facile and green method. Structural characterization indicated α-Fe2O3 nanoparticles were successfully loaded onto PCN. The α-Fe2O3/PCN nanocomposites were proven durable with significantly enhanced photocatalytic activity for Rhodamine B photodegradation than the single components under visible light irradiation. The improved photoactivity was mainly attributed to the broadened visible light absorption, enriched active sites, and formation of α-Fe2O3/PCN heterojunction that addressed the recombination of photoinduced electrons and holes. The α-Fe2O3/PCN hybrids also showed high recyclability and chemical stability.

As a coordination polymer built of [Mo3S13]2- clusters, amorphous nanoscale MoSx (a-MoSx) is an attractive electrocatalyst for the hydrogen evolution reaction (HER) due to its abundant active sites and scalable synthesis. However, clarifying the internal catalytic mechanism and achieving even higher HER performance with scalable size are still challenging. Herein, a new hybrid catalyst of a-MoSx flakes decorated with Ni3S2 nanocrystals (size < 10 nm) has been successfully synthesized on 10 × 20 cm2-sized Ni foam by a portable hydrothermal route. As the strong interaction of [Mo3S13]2- clusters with Ni3S2 is evidenced by comprehensive binding state and Raman characterization, the polymerization effect of [Mo3S13]2- itself and the perfect interfaces between [Mo3S13]2- clusters and Ni3S2 are also confirmed by density functional theory calculations. These two factors greatly lower the absorption energy of hydrogen nearly to zero, leading to much improved HER activity. Current densities of 100 and 600 mA cm-2 are achieved at overpotentials of 181 and 246 mV, respectively, which are so far the highest values approaching practical applications. The findings of this work provide a fundamental reference about the catalytic origin of a-MoSx based catalysts, and shed light on the practical applications of non-precious electrocatalysts for their compatibility with low cost batch production.

Herein, we fabricated a ternary photocatalyst composed of CaFe2O4, multiwalled carbon nanotubes (CNTs) and graphitic carbon nitride (g-C3N4) via a simple hydrothermal route. CaFe2O4 acted as a photosensitizer medium and the CNT acted as a co-catalyst, which remarkably enhanced the photocatalytic performances of g-C3N4 towards the degradation of hexavalent chromium (Cr(VI)) and the antibiotic tetracycline (TC) under visible light irradiation. To investigate the morphological and topological features of the photocatalyst, field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) analyses were performed. The surface properties and oxidation state of the CaFe2O4/g-C3N4/CNT composite were determined by X-ray photoelectron spectroscopy (XPS). The recombination rate of the charge carriers and the band gap values of the as-synthesized catalysts were analyzed by photoluminescence spectroscopy (PL) and diffused reflectance spectroscopy (UV/Vis DRS) studies, respectively. Besides the degradation reactions, the high hydrogen production rate of 1050 μmol h−1 under visible light using the CaFe2O4/g-C3N4/CNT composite loaded with 5 wt% CNT was observed. The superior photocatalytic performances of the CaFe2O4/g-C3N4/CNT composite can be ascribed to the effective heterojunction formed between g-C3N4 and the CaFe2O4 matrix, in which the CNT act as a conducting bridge in the system, promoting the production of photoinduced charge carriers in the semiconductor system. Finally, the plausible photocatalytic mechanism towards the degradation of pollutants and hydrogen production was discussed carefully.

Hydrogen generation photocatalyzed by low-cost graphite carbon nitride (g-C3N4) is a fascinating and effective route to solve energy crisis, but is mainly limited by the few reactive sites, low carrier separation efficiency and mediocre visible-light utilization. In this work, these limitations were tackled through a facile eco-friendly precursor pretreatment by tuning bulk g-C3N4 into porous structure. This pretreatment restricted agglomeration in the subsequent condensation and created more porous channels for charge carrier transfer and more surface active sites for reaction. The modified g-C3N4 has larger surface area, broader visible-light response, enhanced electron migration capacity and prolonged lifetime of photogenerated carriers. These well-amended g-C3N4 nanosheets possess an average hydrogen evolution rate 5.7 times that of bulk g-C3N4. This work affords a facile, eco-friendly and scalable strategy to design or synthesize other porous materials.

MoS2/S-doped porous g-C3N4 (MoS2/SPGCN) hybrids were fabricated via a facile calcination and ultrasound assembly method. Structural characterization indicated MoS2 nanosheets were successfully loaded on SPGCN isotype heterojunction hybrids. The MoS2/SPGCN photocatalysts showed more visible light absorption, larger specific surface area, and faster electron-hole separation. MoS2/SPGCN significantly accelerated Rhodamine B photodegradation under visible light irradiation, which was mainly because the enriched active sites, broadened visible light absorption, and newly-formed heterojunction between MoS2 nanosheets and SPGCN together suppressed the recombination of photoinduced electron-hole pairs. MoS2/SPGCN also showed excellent recyclability and chemical stability. Thus, this work presents a good strategy of designing efficient photocatalysts by substituting the single catalyst base with metal-free isotype heterojunction hybrids.

Herein we report a linear ionic molecule that assembles into a supramolecular nano-tunnel structure through synergy of trident-type ionic interactions and π-π stacking interactions. The nano-tunnel crystal exhibits anisotropic guest adsorption behavior. The material shows good thermal stability and undergoes multi-stage single-crystal-to-single-crystal phase transformations to a nonporous structure on heating. The material exhibits a remarkable chemical stability under both acidic and basic conditions, which is rarely observed in supramolecular organic frameworks and is often related to structures with designed hydrogen-bonding interactions. Because of the high polarity of the tunnels, this molecular crystal also shows a large CO2 -adsorption capacity while excluding other gases at ambient temperature, leading to high CO2 /CH4 selectivity. Aggregation-induced emission of the molecules gives the bulk crystals vapochromic properties.

Herein, two red luminogens with aggregation-induced emission (AIE) characteristics based on simple D–A structures with high performance in the film state are explored. Efficient non-doped solution-processed organic light emitting diodes (OLEDs) are fabricated and emit bright red electroluminescence at 652 nm and 711 nm, respectively. Most importantly, they exhibit CIE coordinates of (0.63, 0.36) and (0.64, 0.35), respectively, which are close to that of primary red color (0.63, 0.34) according to the digital television standard.

We present an all-fiber, all-optical modulator based on a polarization interferometer structure depositing with two-dimensional nanomaterials. Bright and stable modulated output signals can be achieved highlighting the potential for two-dimensional nanomaterial- based photonic applications.

The rapid growth of global energy demand necessitates high-performance water-based drilling fluids (WDFs) with excellent-plugging performance in the deep excavation of shale gas formation. Herein, we report an organic-inorganic nanocomposite (NS-D) as a plugging agent in WDFs to plug the nanoporous of shale and abate the hydration expansion of shale by integrating the advantages of inorganic and polymer nano plugging agents. The results of Fourier Transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (H-NMR) revealed that NS-D had been successfully obtained. Additionally, thermogravimetric analysis (TGA) showed that the thermal degradation temperature of NS-D occurred after 354 °C. The results of plugging theory analysis showed that the presence of rich amide groups and rigid material silica not only made NS-D adhere to shale efficiently by hydrogen bonding, but also firmly blocked the nanoporous of shale. The plugging ability was evaluated by pressure transfer test and nitrogen adsorption test. The results showed that WDFs with NS-D can significantly improve plugging efficiency and reduce fluid invasion. On the other hand, NS-D sharply abated the fluid loss of WDFs due to its positive plugging performance. The filtrate volume of WDFs decreased by 90.5% and 88.3%, respectively, before and after hot rolling at 150°C for 16 h. Moreover, the plugging performance of NS-D for WDFs was significantly better than polymer plugging agent crosslinked polyacrylamide microspheres and inorganic plugging agent silica nanoparticles. This work provides a novel strategy to plug the nanoporous of shale in the process of shale gas exploration.

Wdeemonstrate an all-fiber temperature sensor utilizing a cascaded Mach- Zehnder interferometer and ring resonator with MXene Ti3C2T x , showing a high conversion efficiency of 0.159 π/°C and sensitivity of 1.03 nm/°C.

We demonstrate a self-starting, all-fiber erbium-doped laser mode-locked by graphdiyne-based saturable absorber, delivering 364 fs pulses with 9.18 nm spectral bandwidth. Our work highlights the potential of graphdiyne-based devices for future photonic technologies.

We demonstrate an all-fiber, thulium-doped, mode-locked laser using a black phosphorus (BP) saturable absorber (SA). The BP-SA, exhibiting strong nonlinear response, is fabricated by inkjet printing. The oscillator generates self-starting 139 fs dispersion-managed soliton pulses centered at 1859nm with 55.6 nm spectral bandwidth. This is the shortest pulse duration and widest spectral bandwidth achieved directly from an all-fiber thulium-doped fiber laser mode-locked with a nanomaterial saturable absorber to date. Our findings demonstrate the applicability of BP for femtosecond pulse generation at 2 µm spectral region.

Multifunctional silica-based aerogels are an emerging material due to their unique properties and wide applications. However, their large-scale production and application are limited due to the high cost and cumbersome preparation process. Herein, we prepare graphene oxide (GO)/silica-based composite aerogels via a simple in situ sol-gel reaction. GO nanosheets (GOs) are functionalized with polyethylenimine (PEI) and 3-glycidyloxypropyltrimethoxysilane (GPTMS) successively. After a cohydrolysis and condensation of trimethoxymethylsilane (MTMS) and dimethoxydimethylsilane (DMDMS) in the presence of GOs and a convenient ambient-pressure drying process, the composite aerogels are obtained. In addition to the normal cross-linking of MTMS and DMDMS, the GOs also behave as cross-linking points to significantly enhance the mechanical properties and thermal stability of the network of the composite aerogels. The pore structure of the aerogels is tailored by varying the GO loads as well as its surface modification. The Young's modulus of a composite aerogel with a GO load of 0.5 wt % is about 5 times that for a neat polysiloxane aerogel, and the maximum degradation rate temperature is increased to over 90 °C. Compared with pure polysiloxane aerogel, the thermal insulation and flame resistance are also improved by a small addition of GOs. Moreover, GO/silica-based composite aerogels show stable piezo-resistive behavior. With the excellent mechanical properties, thermal stability, and multifunctionality, GO/silica-based composite aerogels show promising applications under some harsh and extreme conditions.

In an adhesively bonded structure, utilizing the adhesive itself for monitoring the joint integrity can be beneficial in reduction of labor, time, and potential human errors while avoiding problems associated with introduction of a foreign sensor component. This work started from the examination of effective piezoelectricity of commercial structural adhesives/sealants, and five of them were found to possess effective piezoelectric property, with effective piezoelectric coefficient ${d}_{{33}}$ from −0.11 to −1.77 pm/V depending on frequency under substrate clamping condition. With stable piezoelectric response at least up to megahertz, an epoxy adhesive with inorganic filler was selected for structural health monitoring (SHM) feasibility demonstration via generating or sensing guided ultrasonic Lamb waves. The presence of disbond in the adhesive joint is detectable by comparing the Lamb waves signal with a reference baseline signal associated with an intact structure. The results show that the selected adhesive with piezoelectric response can perform the dual roles of structural bonding and ultrasonic joint integrity monitoring.

Skull optical clearing window permits us to perform in vivo cortical imaging without craniotomy, but mainly limits to visible (vis)-near infrared (NIR)-I light imaging. If the skull optical clearing window is available for NIR-II, the imaging depth will be further enhanced. Herein, we developed a vis-NIR-II skull optical clearing agents with deuterium oxide instead of water, which could make the skull transparent in the range of visible to NIR-II. Using a NIR-II excited third harmonic generation microscope, the cortical vasculature of mice could be clearly distinguished even at the depth of 650 μm through the vis-NIR-II skull clearing window. The imaging depth after clearing is close to that without skull, and increases by three times through turbid skull. Furthermore, the new skull optical clearing window promises to realize NIR-II laser-induced targeted injury of cortical single vessel. This work enhances the ability of NIR-II excited nonlinear imaging techniques for accessing to cortical neurovasculature in deep tissue.

Ultrasonic sensors are one of the important technologies for structural monitoring and assessing the structural integrity for aircraft diagnostics and health management. Discrete ultrasonic sensors based on piezoelectric ceramics manually installed on structures have been evaluated for aircraft diagnostics and health management. However, it is challenging and time-consuming to install a large number of bulky and heavy discrete ultrasonic sensors in aircraft. In addition, positioning inaccuracy and bonding quality from the manual sensor installation may result in inconsistency. Direct-write ultrasonic sensors are batch fabricated on the structures using scalable processing method. The sensors have low profile and light weight as they are made of thin layer of coatings (typical total thickness < 100 µm), By eliminating the adhesive layers required for installing discrete sensors, the direct-write sensors offer excellent acoustic coupling with the structure, and thus enable improved reliability and consistency. In this work, two case studies of using direct-write sensors made of piezoelectric polymer coating to detect cracks near fastener holes in aluminum structures are reported. Notches cut from the holes simulated fatigue cracks in Case Study I, and fatigue cracks extended from the notches were involved in Case Study II. The presence of these defects around the fastener holes resulted in reduced signal amplitude of different modes of ultrasonic waves. A computer-controlled testing system was developed to collect time-domain signals at various frequencies and to plot the data into 2D graphs, which can be potentially used as an “ultrasonic signature” of the structure. In addition, damage indexes based on the residual ultrasonic energy were calculated, and could be used as an indicator of severity of damage of the structure.

We demonstrated a multipass-assisted dual-comb gas sensor for the simultaneous and sensitive detection of C2H2 and NH3 near 1.5 μm using a single free-running fiber laser. Two pulse trains generated from the shared cavity in the passively mode-locked fiber laser ensure the mutual coherence and common-mode noise rejection. One of the comb pulse trains passed through an open-path multipass cell with an effective path length of 4 m. A synchronized acquisition technique was adopted for more efficient interferogram acquisition compared with the conventional continuous acquisition method. At an acquisition time of 1.5 s, we obtained a signal-to-noise ratio of more than 600 by 1500 averages of the acquired spectrum of 0.1% C2H2. Pressure broadening of C2H2 and NH3 in the frequency range of 6503–6530 cm−1 between 0.1 and 1 bar were captured by the dual-comb sensor. Finally, the free-running fiber laser-based dual-comb sensor successfully analyzed the C2H2/NH3 mixtures, enabling real-time gas sensing without using complex optical and electronic feedback systems.

We propose a triple-tip spot size converter to further optimize bandwidth and efficiency for edge fiber-to-chip coupling with much improved polarization sensitivity for thick silicon nitride waveguide. It also has good fabrication/assembly error tolerance.

A high-order mode suppressed multimode microresonator is experimentally demonstrated, where a curved waveguide coupler couples out the high-order mode in the multimode ring waveguide and leaves the fundamental mode undisturbed, as a low-loss mode filter.

Fractures and fracture networks are key conduits for migration of hydrothermal fluids, water and contaminants in groundwater systems Modeling is widely used to understand the environmental risk associated with migration of pollutant for different hydrogeological conditions. In this paper, we proposed a conceptual and mathematical model of flow and transport phenomena in fractured rock systems, and applied in a arsenic contaminate site as a case study. The groundwater flow model and arsenic migration model in fissure-matrix dual system were established. The results show that the velocity of groundwater is positively correlated with inlet pressure, but not with the porosity of the fracture. When the velocity of groundwater is relatively high, arsenic is transported along with the current in a finger-like manner. The distribution of arsenic concentration on the fracture surface is heterogeneous and the phenomenon of diffusion from the fracture to the matrix is not obvious. Indeed, when the velocity of groundwater is relatively small, the arsenic moves forward slowly, the concentration distribution on the crack surface is relatively uniform, and the diffusion phenomenon from the crack to the matrix is more significant.

We demonstrate an all-fiber Tm-doped mode-locked fiber laser utilizing a black phosphorus saturable absorber. The oscillator delivers self-starting, 139 fs pulses centered at 1859 nm with 55.6 nm spectral bandwidth.

Corrosion in internal cavity is one of the most common problems occurs in many hollow metallic components, such as pipes containing corrosive fluids and high temperature turbines in aircraft. It is highly demanded to non-destructively detect the corrosion inside hollow components and determine the corrosion extent from the external side. In this work, we present two high-frequency ultrasonic non-destructive testing (NDT) technologies, including piezoelectric pulse-echo and laser-ultrasonic methods, for detecting corrosion of Ni superalloy from the opposite side. The determination of corrosion layer thickness below ∼100 µm has been demonstrated by both methods, in comparison with X-CT and SEM. With electron microscopic examination, it is found that with multilayer corrosion structure formed over a prolonged corrosion time, the ultrasonic NDT methods can only reliably reveal outer corrosion layer thickness because of the resulting acoustic contrast among the multiple layers due to their respective different mechanical parameters. A time-frequency signal analysis algorithm is employed to effectively enhance the high frequency ultrasonic signal contrast for the piezoelectric pulse-echo method. Finally, a blind test on a Ni superalloy turbine blade with internal corrosion is conducted with the high frequency piezoelectric pulser-receiver method.

Dual-comb spectroscopy schemes have been demonstrated as an attractive solution for advanced optical spectroscopic analysis. The widely used fiber Bragg grating (FBG) sensing could benefit from the high spectral resolution and broad spectral coverage they could offer. However, the complexity, cost, and size of traditional dual-comb systems are prohibitively high for FBG applications. Dual-wavelength mode-locked fiber laser can generate two asynchronous ultrashort pulse trains and could enable the development of compact and low-complexity dual-comb application systems. In this paper, we propose and demonstrate a high-resolution, dynamic FBG interrogation scheme based on dual-comb spectroscopy with one free-running fiber laser. Accurate spectroscopic measurement of the FBG’s reflective spectrum is realized with each acquired dual-comb interferogram without further averaging. In our experiments, the resolution of such single-shot FBG wavelength measurement results can reach 1.7 pm, while the spectral non-aliasing measurement range is over 10 nm. Enabled by this capability of making fast dual-comb spectroscopy measurement of the FBG sensor response, the sampling speed of the interrogation system can reach the repetition rate difference of the dual combs, e.g., 1 kHz in this demonstration. Dynamic measurements of FBG responses driven by frequency up to 400 Hz are experimentally demonstrated. Our results further illustrate the potential and advantages of such single-cavity dual-comb laser sources in realizing low-complexity dual-comb systems that could appeal to a wider variety of applications.

In order to meet the targeted dispersion requirements of applications, hybridized modes of coupled waveguides, whose dispersion characteristics can be significantly altered around their mode cross-point, have been recently investigated. The applications have been applied to microresonators based on concentric waveguides with a thin silicon nitride layer. However, it is still challenging to achieve a low and flattened anomalous dispersion profile just by optimizing the gap width between the waveguides. We propose to investigate the dispersion characteristics of coupled silicon nitride waveguides with a partially etched gap. It is shown that low and broadband anomalous dispersion can be achieved based on relatively thin 515 nm thick silicon nitride layer waveguides. The mechanism of a partially etched gap on dispersion engineering can be attributed to the tuning of the coupling strength between the waveguides. Therefore, when combined with other design parameters, it offers an additional "tuning knob" of advanced dispersion engineering when designing such coupled-waveguide devices for nonlinear photonic applications.

Octave-spanning frequency comb generation in the deep mid-infrared (>5.5 μm) typically requires a high pump power, which is challenging because of the limited power of narrow linewidth lasers at long wavelengths. We propose twofold dispersion engineering for a Ge-on-Si microcavity to enable both dispersion flattening and dispersion hybridization over a wide band from 3.5 to 10 μm. A two-octave mode-locked Kerr frequency comb can be generated from 2.3 to 10.2 μm, with a pump power as low as 180 mW. It has been shown that dispersion flattening greatly enhances the spectral broadening of the generated comb, whereas dispersion hybridization improves its spectral flatness.

A novel and simple sensing scheme based on the giant Goos-Hanchen shift enhanced by the excitation of the Bloch surface wave in a truncated one-dimensional photonic crystal structure is proposed and experimentally demonstrated. The significantly enhanced Goos-Hanchen shift is directly measured by a position sensitive detector and the following amplifier. The bulk refractive index sensitivity of the sensor is investigated by utilizing sodium chloride solutions and glycerol solutions with different concentrations as test samples. The results show that the Goos-Hanchen shift sensor has a superior sensitivity of 2.0*10−9 RIU/nm, which outperforms the SPR enhanced Goos-Hanchen shift sensors.

Microwave photonic solutions of frequency measurement have advantages in broad frequency coverage, but achieving high-resolution measurement remains a challenge. Those schemes based on optical frequency combs could achieve high-resolution measurement over a broad frequency range. Here, a dead-band-free, high-resolution microwave frequency measurement scheme based on undersampling the microwave signal by three pulse sequences generated from a triple-wavelength mode-locked fiber laser is proposed and demonstrated. The triple-wavelength ultrashort pulses generated in one laser cavity have slightly different repetition rates due to chromatic dispersion. This eliminates the needs of multiple mode-locked lasers and frequency control between them and drastically reduces the system complexity. The absolute frequency of the microwave signal can be determined based on three down-converted low-frequency beat notes of the microwave signal with the nearest comb lines without ambiguity. A 10–10 relative measurement precision at a sampling speed of 100 Hz is demonstrated from 1 to 20 GHz, and the measurement accuracy remains within 0.3 Hz. Microwave signal with an RF power as low as −75 dBm can be measured with a 10 Hz precision at 10 GHz by using RF frontend amplifiers. The simple and compact triple-comb fiber laser would enable the development of low-complexity, high-performance microwave characterization instrument.

For large-scale pressurized water reactor (PWR) deep-penetration shielding calculation, Monte Carlo (MC) method requires simulating a great number of particles to obtain reliable results, thus huge amount of computation time is the main problem of the MC method. Discrete Ordinates-Monte Carlo (SN-MC) coupling method combines the advantage of the SN method with high efficiency and the MC method with fine geometrical modeling. This paper studies the 3D SN-MC coupling method, generates surface source using the angular fluence rates of a SN code JSNT, and develops a source sampling subroutine for a MC code JMCT. The coupling method is verified on measurements and applied to CAP1400 cavity streaming calculation. Numerical results show that the coupling method increases calculation efficiency by 2–10 times for deep-penetration shielding calculation with high precision compared with reference results. The coupling method is effective for large-scale PWR deep-penetration shielding calculation.