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In this study, a new alloy material Mg-Zn-Zr (ZK60) was designed for the connecting rod. It was found that the blanks sampled along the vertical direction of an extruded bar crack during the roll forging process. The microstructure and precipitates of the extruded bar were observed and analyzed using optical microscope (OM), scanning electron microscope (SEM) and x-ray diffraction (XRD). The result showed that the Zn, Zr, and MnZn2 precipitates were elongated along the extrusion direction. The mechanical anisotropy was investigated by testing the mechanical properties of the specimens sampling from different angles. Hot deformation behavior was further studied using the Gleeble 3500 thermal-mechanical simulator. The tensile and yield strengths were the highest along the extrusion direction, reaching 347 MPa and 301 MPa, respectively. The deformation resistance was also higher in the extrusion direction than that in the vertical direction. Fracture mechanisms of the sample from different directions were discussed. The ZK60 alloy was more susceptible to failure if the deformation direction was parallel to the bands of segregation area and precipitates.

Based on cohesive zone model (CZM), a simplified method for estimating the tensile softening curve of quasi-brittle materials is proposed. First, assume that the virtual crack opening displacement ...

The coin-tap method performs nondestructive testing by measuring the width of the tapping response pulse on the surface of the material. Existing studies have shown that defects in the material will cause the width of the tapping response pulse to increase. However, experiments have confirmed that different detection positions in the defective area will show different values of the width of the tapping response pulse, and the physical laws behind it have not been studied yet. To discuss its physical meaning, a mathematical model of the defective area is established, a method for calculating the width of the tapping response pulse is proposed, and a composite honeycomb structure with preset defects is used for data testing. Both the test results and the calculation results show that the pulse width of the tapping response will decrease with the increase of the defect depth and the deviation of the tapping position from the defect center. The consistency between the calculated results and the experimental results shows that the established defect model and pulse width calculation method can better explain the distribution law of the pulse width of the tapping response in the defective area.

An initial attempt had been made to fabricate Ni Al intermetallic compounds (IMCs) by wire arc additive manufacturing (WAAM) in order to overcome the disadvantages of traditional casting-melting method such as complex process and long production cycle. The effects of wire Ni content on the microstructure and mechanical properties of the deposited thin-wall samples were studied. It was found that the deposited microstructure varied from M-NiAl/Ni3Al to bulk-like Ni3Al + γ-Ni/γ′-Ni3Al by increasing the Ni content. The average microhardness of the deposition firstly decreased from 437.6 HV0.3 to the minimum of 255.4 HV0.3 with the increase of the Ni content because of the decrease of the M-NiAl with high hardness. It then increased to 302.1 HV0.3 owing to the increase of the strengthened phase of γ′. The thermodynamic behavior in Ni Al system was calculated to discuss the transformation mechanism of the WAAMed Ni Al IMCs.

Phototherapy holds great promise in the treatment of bacterial infections, especially the multidrug resistant bacterial infections. However, most therapeutic agents are based on the integration of individual photothermal agents and photosensitizers, always in the activated state, and generally lack bacterial specificity, resulting in uncertain pharmacokinetics and serious nonspecific damage to normal tissues. Herein, we report a pH-responsive nanoplatform with synergistic chemo-phototherapy function for smart fluorescence imaging-guided precision sterilization. pH reversible activated symmetric cyanine was designed and prepared as a bacterial-specific imaging unit and PTT/PDT-in-one agent. Meanwhile, a guanidinium-based covalent organic framework (COF) was employed as a nanocarrier and chemotherapy agent to build the intelligent nanoplatform via electrostatic self-assembly. The self-assembly of the PTT/PDT-in-one agent and the COF greatly improves the stability and blood circulation of the PTT/PDT-in-one agent and provides charge-reversed intelligent targeting ability. The developed smart nanoplatform not only enables bacterial-targeted imaging but also possesses chemo/PTT/PDT synergetic high-efficiency bactericidal effects with little side effects, showing great potential in practical applications.

Ceramic aerogels, which present a unique combination of low thermal conductivity and excellent high-temperature stability, are attractive for thermal insulation under extreme conditions. However, most ceramic aerogels are constructed by oxide ceramic nanoparticles and thus are usually plagued by their brittleness and structural collapse at elevated temperatures (less than 1000 °C). Despite great progress achieved in this regard recently, it still remains a big challenge to design and fabricate intriguing ceramic aerogels with enhanced mechanical strength and remarkable thermal stability at ultrahigh temperature up to 1400 °C. To this end, we herein report a facile and scalable strategy to manufacture ceramic nanorod aerogels (CNRAs) with hierarchically macroporous and mesoporous structures by the controllable assembly of Al2O3 nanorods and SiO2 nanoparticles. Subsequently, the high-temperature annealing treatment of CNRAs significantly maximizes mechanical strength and promotes thermal tolerance. The obtained CNRAs demonstrate the integrated properties of super-strong heat resistance (up to 1400 °C), low thermal conductivity (0.026 W/m·K at 25 °C and 0.089 W/m·K at 1200 °C), high mechanical robustness (compressive strength 1.5 MPa), and low density (0.146 g/cm3). We envision that this novel nanorod-assembled ceramic aerogels offer considerable advantages than most of the state-of-the-art ceramic aerogels for thermal superinsulation upon exposure to extremely harsh environments.

The austenite grain refinement and homogenization control strategies of the flexspline were investigated, including microalloying with V and Ti, the evolution of austenite grain size and homogenization during forging processes and multiple times of heat treatment. The results show that the grain growth rate during high temperature was lowered obviously which leads to the grain refinement, owing to the addition of microalloying elements V and Ti. After holding at 1200 °C for 40 min, the average grain size of 0.05%V+0.0045%Ti steel was reduced by 39% compared with 0.04%V+0.0025%Ti steel. During the manufacturing process of the flexspline from induction reheating to quenching and tempering, the austenite grain was gradually refined from 340.0-380.7 to 9.3-9.8μm. The grain size and homogenization were improved obviously in the first two times during the multiple times of normalizing. After multiple times of quenching and tempering, the size and homogenization of the grain were gradually improved. The exponential relationship between grain size and multiple times of normalizing and the linear relationship between grain size and multiple times of quenching and tempering were also obtained, respectively.

In recent years, the oil field chemical A-cyanoacrylate mixed adhesive has been used in rock preparation and preparation to a certain extent, and its role has been paid more and more attention due to the solidification of the rock surface in the rock thin section, the early embedding of the rock, and the adhesion of the thin side of the rock to the slide surface, etc. This paper introduces the preparation and application development of a-cyanoacrylate mixed adhesive in geological experiment, and the development of a-cyanoacrylate mixed adhesive in oilfield geological experiment.

Underwater acoustic ranging and detection usually require hydrophones to have high sensitivity at narrowband operating frequencies. Different from traditional sensitization methods with the help of new materials and solid/liquid resonance structure, this paper proposes a low-cost, high-sensitivity hydrophone based on a resonant air cavity containing an affordable MEMS microphone inside to sense the focused acoustic waves transmitted from the external water across the solid shell into the air cavity. Both finite element simulations and experiments are carried out to test its acoustic sensing performances. Resonance frequency and directivity of the proposed hydrophone are determined by the air cavity size and the acoustic mode, but is independent of the solid shell, which facilitates the precise designability. The sensitivity of the developed hydrophone at the resonance frequency is up to −157 dB re 1V/ $\mu $ Pa calibrated by commercial standard hydrophone TC4013. Finally, several further considerations, improvements and applications on the proposed hydrophone are discussed.

Isothiocyanate liquid crystals containing cyclohexene core unit were designed and synthesised through a practical synthetic route. The structures of the designed mesogens and intermediate products ...

Phototherapy has great potential to revolutionize conventional therapeutic modalities. However, most phototherapeutic strategies based on multicomponent therapeutic agents generally lack tumor-specificity, resulting in asynchronous therapy and superimposed side-effects. Severe heat damage is also inevitable because of the necessity of continuous external irradiation. Here we show the design of an acid-activated and continuous external irradiation-free photothermal and photodynamic (PTT/PDT) synchronous theranostic nanoplatform for precision tumor-targeting near-infrared (NIR) image-guided therapy. pH-reversibly responsive brominated asymmetric cyanine is designed as the tumor-specific NIR PTT/PDT-in-one agent to enhance anticancer efficiency and reduce side-effects. Ultra-small NIR persistent luminescence nanoparticles are prepared as both the imaging unit and renewable nanoimplant. Biotin functionalized polyethylene glycol is introduced to endow active tumor-targeting ability and prolong blood-circulation. The developed smart platform offers merits of reversible activation, PTT/PDT synergetic enhancement, tumor targetability and continuous external irradiation-free properties, allowing autofluorescence-free image-guided phototherapy only in tumor sites. This work paves the way to developing smart theranostic nanoplatforms for precision medicine., A smart NIR photothermal/photodynamic-in-one agent integrated with renewable nanoimplants for autofluorescence- and continuous external irradiation-free image-guided precision tumor-targeting phototherapy.

Solar cells can operate at a lower efficiency after a certain temperature, which is caused by a negative thermal coefficient. Therefore, the temperature prediction of photovoltaic (PV) modules is critical to accurately evaluate the efficiency of photovoltaic devices. We propose and experimentally demonstrate a Fuzzy Temperature Difference Threshold Method (FTDTM) based on Raman Distributed Temperature Sensor (RDTS) system for the detection and prediction of PV module temperature. The FTDTM consists of four steps, i.e., division of the universe, establishment of fuzzy relationships, definition of relationship matrix and calculation of predicted temperature. The experimental results show that the proposed RDTS can detect and accurately predict temperature trends by using the FTDTM. When the system window base of the FTDTM is set to 2, the average absolute error of the predicted temperature is 1.08 °C, and the fluctuation range of prediction error is ±3.7 °C. In addition, the experiment studied some factors affecting temperature distribution characteristics of PV modules, including solar radiation intensity, surface dust and inclination angle. We provide a solution for large-scale PV module temperature detection and early warning through RDTS systems with FTDTM.

Persistent luminescent nanoparticles (PLNPs) with intrinsic stimuli-responsive properties are desirable because of no autofluorescence background and natural responsive luminescence. However, the stimuli-responsive features of pure PLNPs have been unexplored. Here we show a facile one-pot hydrothermal synthesis of green-emitting Zn2 GeO4 :Mn2+ ,Pr3+ nanoparticles (ZGMP) with regular shape, uniform size and good afterglow luminescent performance. We also report the pH stimuli-responsive luminescent behavior of ZGMP and its possible mechanism. Taking the intriguing feature of pH responsive persistent luminescence, we explore ZGMP as autofluorescence-free probes to achieve stimuli-activated signal switch for biosensing by integrating enzyme catalysis reaction mediated pH modulation. The pH-responsive persistent luminescence also makes ZGMP promising for high-level information encryption.

Novel hydrophilic NaYF4:Yb3+,Tm3+@NaGdF4:Ce3+,Eu3+ double-jacket microtubes (DJMTs) with upconversion/ downconversion dual-mode luminescence were designed and prepared through epitaxial growth of NaGdF4:Ce3+, Eu3+ shell onto the NaYF4:Yb3+,Tm3+ microtube via poly(acrylic acid) (PAA) mediated hydrothermal method. It is demonstrated that PAA ligand played an important role in guiding the direct growth of NaGdF4:Ce3+,Eu3+ shell onto the surface of NaYF4:Yb3+,Tm3+ parent microtubes. The growth of NaGdF4:Ce3+,Eu3+ shell experienced a crystal phase transition from β-NaGdF4 and β-NaYF4 mixture to β-NaYF4@NaGdF4 composite crystal, and morphology evolution from mixture of β-NaGdF4:Ce3+,Eu3+ nanorods and β-NaYF4:Yb3+,Tm3+ microtubes to NaYF4:Yb3+,Tm3+@NaGdF4: Ce3+,Eu3+ DJMTs. The formation mechanism of DJMTs was the dissolution−renucleation of β-NaGdF4:Ce3+,Eu3+ nanorods and the growth of β-NaGdF4:Ce3+,Eu3+ shell via the classical Ostwald ripening mechanism. The as-prepared DJMTs could exhibit blue upconversion and red downconversion luminescence, which was further made into environmentally benign luminescent inks for creating highly secured and fluorescent-based anti-counterfeiting patterns via inkjet printing.

Issues like morphology control and further multifunctional applications are of significant importance for rare earth nano-oxides, e.g., cerium dioxide (CeO2) nanostructures, however, relevant results in this respect are rather limited up to now. In the present work, ultrathin CeO2 nanosheets were synthesized through a facile low-temperature hydrothermal method. The structure, morphology and specific surface area of these CeO2 nanosheets were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and N2 adsorption–desorption. Significantly, CeO2 nanosheets have the potential as bifunctional sensing materials to detect both humidity and formaldehyde vapor. The CeO2 nanosheet humidity sensor exhibited excellent sensing characteristics in the relative humidity range of 11%–97% with the response value as high as 3.1 × 104. Meanwhile, the CeO2 nanosheet gas sensor showed superior sensitivity and repeatability with fast response/recovery speed toward formaldehyde vapor at 300 °C. Finally, the humidity and formaldehyde sensing mechanism were discussed as well.

P-xylene (p-C8H10) is extremely harmful and dangerous to human health due to high toxicity and strong carcinogenicity. Exploring sensitive material to effectively detect p-xylene is of importance. In this paper, perovskite single crystal (C4H9NH3)2PbI4 has been successfully synthesized via solution method. The obtained product was analyzed by single crystal X-ray diffraction. With the space group Pbca, orthorhombic (C4H9NH3)2PbI4 layered perovskite structure consists of an extended two-dimensional network of corner-sharing PbI6 octahedron. Single layer perovskite sheets of distorted PbI6 octahedron alternated with protonated n-butylammonium cation bilayers, which offers many advantages and provides the possibility of forming a gas sensor device based on the change of resistances. Density functional theory (DFT) simulations regarding the adsorption energy revealed that this organic–inorganic hybrid perovskite compound has excellent selectivity toward p-xylene compared with other gases including C2H5OH, C6H6, CH2Cl2, HCHO, CH3COCH3 and C7H8. The calculation of electron density, density of states and electron density difference showed the sensing mechanism of p-C8H10 is mainly derived from physical adsorption–desorption in view of electron transfer. For organic–inorganic hybrid perovskite (C4H9NH3)2PbI4, single layer perovskite sheets of distorted PbI6 octahedron alternated with protonated n-butylammonium cation bilayers (a), which offers many advantages and provides the possibility of forming a gas sensor device based on the change of resistances. Electron density difference calculation shows that adsorption of p-xylene molecule has an obvious effect on the electron distribution of (C4H9NH3)2PbI4, results in electrically polarization as a local manner (b).

Graphitic carbon nitride (g-C3N4) can be indexed as a high-content N-doped carbon material, appealing great attentions in energy storage devices. However, poor conductivity and serious irreversible capacity loss were found for the g-C3N4 due to its high nitrogen content. Urea, dicyandiamide or melamine can be used as organic precursor to form g-C3N4 because they can be pyrolyzed into g-C3N4 easily. In this work, high nitrogen content (up to 17 at.%)-doped carbon materials embedded with superfine-Sn particle are synthesized by one-step thermal treatment of the g-C3N4 organic precursor and SnCl2 in a simple self-designed quartz tube. Regarding their high nitrogen doping content, large surface area and porous structure, the obtained material could deliver a high specific capacity and excellent capacity retention when applied as lithium ion battery anode. Its excellent rate performance is attributed to the high Li diffusion coefficient demonstrated by the GITT kinetics analysis. This extremely simple and low-cost preparation process could provide a new strategy to obtain high nitrogen content carbon-based materials.

The effect of the content of an SiO2 additive on the electrochemical reduction of ilmenite concentrate to prepare ferrotitanium is investigated in CaCl2 molten salt. A thermodynamic analysis of the Ti-Fe system and possible reactions has been carried out, and it demonstrated that SiO2 and FeTiO3 can be readily reduced to Si and intermediates (Fe and CaTiO3), respectively. The experimental results demonstrated that the optimal molar ratio of Ti:Fe:Si in the cathode mixtures is 1.2:1:0.2. The porous ferrotitanium with uniform particle sizes were successfully obtained by electrolysis at 1173 K with a cell voltage of 3.2 V for 2 h. The SiO2 additive plays an important role during the formation process of ferrotitanium, which is first reduced to Si and then serves as a reductant to catalyze CaTiO3 and Fe to form FeTi alloys.

Photodynamic sterilization is the most promising method to combat bacterial infection, especially multidrug-resistant bacterial infection. However, the absorption of conventional photosensitizers is mostly located in the UV-vis region, leading to limited penetration depth and poor therapeutic efficacy for deep-tissue bacterial infection. Besides, most of the photosensitizers are always in the activated state and lack bacteria-targeting ability, which inevitably causes severe nonspecific damage to normal tissues. Here, we show the design of a pH reversibly switchable near-infrared photosensitizer-based nanocapsule for precision bacteria-targeting fluorescence imaging-guided photodynamic sterilization. pH reversibly activatable asymmetric cyanine was synthesized as a bacteria-specific imaging unit and smart photosensitizer to realize precision imaging-guided targeting sterilization without side effects. An allicin mimic was introduced into the smart photosensitizer as the auxiliary bactericidal group to further enhance antibacterial efficiency. Meanwhile, amphipathic functionalized polyethylene glycol was employed to fabricate the nanocapsule by self-assembly to endow the charge-reversed intelligent targeting ability and prolong blood circulation. The developed switchable nanocapsule not only enables precision bacterial infection-targeted imaging without background fluorescence interference but also gives an efficient bactericidal effect with excellent specificity and negligible side effects, holding great potential for practical application.

Rock destruction under high-temperature conditions is a key issue for nuclear waste treatment projects, underground coal gasification, and improvement of the use of geothermal energy for heating. Therefore, in this study, various methods and techniques were integrated to study the changes in mechanical properties, mineral composition, and microscopic fracture characteristics of Sichuan sandstone treated at 600°C. First, the fracture toughness and indirect tensile strength of untreated sandstones and high-temperature treated sandstones were tested by the MTS testing machine, and the double-K model (DKFM) was used to estimate the unstable fracture toughness. Then, the diffraction spectra of sandstone were analyzed with an X-ray diffractometer to determine the mineral composition change after heat treatment. Finally, the microscopic features of sandstone were observed through a scanning electron microscope (SEM) and optical microscope. The results show the following. (1) There is no significant change in the tensile strength and fracture toughness of Sichuan sandstone treated at 600°C. (2) The brittleness of Sichuan sandstone decreases and the ductility increases after high-temperature treatment. (3) The unstable fracture toughness value Kun obtained by the double-K model (DKFM) is significantly larger than the apparent fracture toughness value Kif. (4) After treatment at 600°C, the clay minerals in the sandstone changed significantly. Kaolinite is dehydroxylated to metakaolinite, which may increase the ductility of the rock.

In order to effectively remove mercury from raw natural gas, a preparation method of columnar sulfur-impregnated activated petroleum coke was proposed and mercury adsorption experiments were conduc...

In this paper, new liquid crystal compounds with negative dielectric anisotropy were synthesised by regulating the substituents on the benzofuran ring. Their structures were confirmed by 1H-nuclear...

New liquid crystal compounds with 5,6-difluorobenzofuran core were synthesised by palladium catalysed coupling and ring-closing reaction. Their structures were identified using 1HNMR, 13CNMR and MS...

Insulation oil is an important dielectric in power devices, and many studies on mixed insulation oil have been conducted in recent years to improve the performance of insulation oils. To replace mineral oil directly, the authors previously developed a novel three-element mixed insulation oil successfully; the main parameters of which satisfy the IEC 60296-2012 standard for mineral oil. In the present study, the AC breakdown properties of insulation paper (pressboard) immersed by the new mixed oil and naphthenic mineral oil were compared. For both insulation oils, the increase in temperature cannot significantly reduce the breakdown strength of oil-immersed insulation paper (pressboard) at a low moisture content, and the increment of moisture content cannot reduce the breakdown voltage at a low temperature (25°C). The breakdown voltage decreases only when the two factors increase simultaneously. For the mixed and mineral oils, the AC breakdown voltage of oil-immersed paper (pressboard) with different thicknesses has significant difference. The mineral oil has a high breakdown voltage for the thin insulation paper, whereas the mixed oil has a high breakdown voltage when the thickness of the insulation paper (pressboard) exceeds 0.2 mm. This phenomenon is mainly caused by the breakdown field strength that varies with the increase of dielectric thickness and the different change trends of paper (pressboard) immersed with the mixed and the mineral oils. Moreover, the stack of thin multilayer insulation paper enables the mixed oil-immersed paper to have a higher breakdown strength than the mineral oil-immersed paper. For the AC breakdown voltage of oil-immersed pressboard with an oil-gap structure, the mixed oil is comprehensively superior to the mineral oil due to its larger relative permittivity.

Ten new negative dielectric anisotropy liquid crystal compounds with terminal 2-fluoroethyl group were synthesised and their structures were confirmed by 1H-nuclear magnetic resonance and mass spec...

The practical application of carbon fiber (CF)-reinforced polyimide (PI) resin composite was hampered seriously by the poor interfacial adhesion property. In this work, a novel surface treatment agent was designed and prepared to improve the interfacial strength by covalently bonding CF with PI matrix, which is beneficial to the uniform dispersion and impregnation of PI between CF, thereby improving the mechanical properties of CF/PI composites to some extent. The CF was characterized by high surface roughness, which means better wettability by PI. As a result, the interfacial shear strength and interlaminar shear strength of CF/PI composites were enhanced, benefited mainly from the strong and tough interphase.

In this study, an easy and low-temperature differential hollow roller using an ultra-thin heating element of graphene polymeric composite material by wire bar coating technique was first demonstrated and fabricated successfully. In contrast to the conventional hot roller, this study confirmed the flexibility of high uniform temperature distribution in the rolling system. The dynamic-state temperature differential of four quarter positions and horizontal positions can be controlled within 2.8 °C and 1.2 °C with a voltage of 40 V, respectively. High-Temperature stability of long-term steady-state temperature was confirmed and the voltage only needs 25 V to get a steady-state temperature of almost 160 °C.

Carbon dots (CDs) have been used for the first time as a sensitizer to initiate and activate free radical and controlled radical polymerization, respectively, based on an ATRP protocol with blue LEDs. Consideration of diverse heteroatom‐doped CDs indicated that N‐doped CDs could serve as an effective photocatalyst and photosensitizer in combination with LEDs emitting either at 405 nm or 470 nm. Free radical polymerization was initiated by combining the CDs with an iodonium or sulfonium salt in tri(propylene glycol) diacrylate. Polymerization of methyl methacrylate (MMA) by photo‐induced ATRP was achieved with CDs and ethyl α‐bromophenylacetate using CuII as catalyst in the ppm range. The polymers obtained showed temporal control, narrower dispersity ≲1.5, and chain‐end fidelity. The first‐order kinetics and ON/OFF experiments additionally gave evidence of the constant concentration of polymer radicals. No remarkable cytotoxic activity was observed for the CDs, underlining their biocompatibility., On the dot: Carbon dots isolated from seaweed work well as a photocatalyst and sensitizer in living and free radical polymerization, while their low cytotoxic activity makes them interesting for medical applications.

In the field of temperature safety monitoring, it is important to quickly locate the position of temperature anomalies and start to alarm. The multimode fiber (MMF) has a certain temperature hysteresis effect when detecting the surrounding temperature along the sensing fiber, it deteriorates the warning-time of Raman distributed temperature sensor (R-DTS). This paper proposed and experimentally demonstrated an R-DTS with heat transfer functional model to perceive the surrounding temperature in advance. The temperature hysteresis effect of MMF cable in different temperature conditions are studied experimentally. The experimental results show that the temperature change rate of MMF and the surrounding temperature difference maintains a linear relationship after fitting. And this fitting relationship is used to perceive the surrounding temperature anomalies along the MMF for R-DTS system. The experimental results indicate that the warning-time of R-DTS can optimize from 23.4 s to 1.3 s at the temperature condition with 60 °C. It proves that this analytical model of the heat transfer function model can quickly perceive the environment temperature anomalies to avoid the temperature hysteresis effect of MMF at the difference temperature conditions. The research content can be applied in the temperature safety monitoring with high requirements for early-warning time, such as fire monitoring, power cable safety monitoring, and gas pipeline leakage detection.

Six benzoxazole-terminated mesogenic compounds with fluoro substituent at different positions were prepared and their properties investigated. The compounds give a high birefringence (Δn~ 0.45) and...

Thermal buckling of subsea pipelines often occurs and seriously threatens pipeline safety. The spherical detector (SD) can realize quasi real-time detection of pipeline buckling owing to its low blockage risk and convenient launch-retrieval deployment. Vertical buckling can be judged by the rolling speed of the SD, while lateral buckling can only be judged by the interior magnetic fields. However, irregular magnetic remanence of the pipeline seriously hinders the magnetic detection of lateral buckling. To against this problem, this paper proposes a method of detecting the lateral pipeline buckling via demagnetization and interior magnetic measurement. It is experimentally demonstrated that demagnetization can remove most of the remanence of the pipeline and make the interior magnetic fields more regular and uniform; After the pipe is demagnetized, both severe and weak lateral bucklings can be sensitively indicated by the single or double peaks of the interior magnetic fields measured by the SD. The interior magnetic fields are also experimentally demonstrated capable of indicating the first and recurring weak buckling through comparing with the previous detection data.

Phototheranostics has attracted great interest in cancer therapy. Small-molecule self-reporting photosensitizers, one kind of idea agent in phototheranostics, enables simultaneous photodynamic therapy (PDT) and feedback of therapeutic efficacy. However, previous such photosensitizers exclusively employed the change of single emission to monitor cell death, which can be disturbed by variations in photosensitizer concentration and the excitation intensity. Herein, we report a unique self-reporting photosensitizer TPA-3PyA+ constructed from a twisted triphenylamine unit (TPA), three benzene ring units and three cyanovinyl-pyridinium units (PyA) for PDT and its real-time monitoring in a dynamic dual-color mode. TPA-3PyA+ possesses a rotatable electron donor-π bridge-electron acceptor framework and exhibits high singlet oxygen quantum yield (124%) and a twisted intramolecular charge transfer (TICT) effect. TPA-3PyA+ not only enables effective staining of cancer cells with dual-color fluorescence due to the TICT effect but also shows excellent PDT performance. The simultaneous change in emission color, intensity and intracellular location of TPA-3PyA+ during cell death allows it to self-report cell death. Moreover, the change of dual-emission color allows distinguishing living and dead cells and effectively avoids interference in previous single-emission self-reporting photosensitizers. This work highlights the great potential of a self-reporting photosensitizer with dual-color emissions for efficient feedback of theranostics.

Persistent luminescence nanoparticles (PLNPs), also called long-lasting afterglow nanoparticles, are magical materials that can emit long-lasting luminescence after excitation ceases. Moreover, the luminescence can be reactivated under appropriate excitation light. Such excellent optical nature enables the detection of persistent luminescence with no need for in-situ continuous excitation, thereby effectively eliminating autofluorescence interference and scattering light from complex matrixes. PLNPs, therefore, have become emerging optical materials in biological applications with bright prospect. In this review, we summarize the recent progress in autofluorescence-free chemo/biosensing, and highlight the design strategies of PLNPs-based sensors. In addition, we also make perspective on opportunities and challenges for further development in this field.

IEEE In this paper, the detent force caused by the end effect in a flux-switching permanent magnet linear motor (FSPMLM) with 6 slots and 5 poles is investigated and reduced by two different methods. Firstly, the detent force is diminished by adjusting the position of end teeth of primary side and injecting compensation current into compensation windings wound around the end teeth. Based on the linear relationship between compensation current and compensation force, the proper compensation current is derived and analyzed. Then, to avoid the magnetic coupling between compensation windings and phase windings, a novel compensation module with independent magnet circuit is presented and attached to the primary side of FSPMLM. Thirdly, the two detent force reduction methods are compared with each other, and the compensation module is proved to be more effective. Finally, a prototype of FSPMLM with compensation modules is manufactured and tested to validate the proposed compensation method.

In recent years, optic-fiber sensors have been required to simultaneously measure the structure's crack and environmental temperature in the infrastructure monitoring system. We proposed and experimentally demonstrated a distributed optic-fiber sensor based on the Raman loop configuration and fiber loss characteristic for detecting the temperature and structure's crack. Among them, the Raman loop configuration with reference fiber is proposed to detect the temperature profile along the sensing fiber. It can eliminate the influence of external physical perturbation on the temperature measurement results, and do not require pre-calibration process before measurement. The temperature experimental results show that the temperature accuracy and spatial resolution can reach up to 0.28 °C and 1.2 m with the response time of 1.04 s. In addition, the information of crack is extracted by using the loss characteristics of Stokes, which is based on optical time domain reflectometry. The experiment results indicate that the fiber loss coefficient keeps a good linear variation between the crack ranges of 1.6 mm and 5.6 mm. The studies achieve the temperature and crack measurement only by one fiber.

Hierarchical structured materials represent an interesting platform for many potential applications such as separation, catalyst and drug delivery etc. However, controlled fabrication of this special structure still remains a big challenge. In the present work, a controllable sol-gel procedure was developed to precisely fabricate polysilsesquioxane particles with bowls-on-sphere structure from mixed organoalkoxysilane precursors with sodium ligninsulfonate as surfactant and polystyrene spheres as structure-directing agents. The morphology of the particles can be fine-tuned by judiciously adjusting the ratio of two silane precursors, amount of ammonia, surfactant content and polystyrene amount. The formation mechanism of spheres-on-sphere structured polysilsesquioxane particles was explored.

Semiconducting metal oxides (SMO) have been investigated as important gas sensing materials for detecting various inflammable and toxic gases; however most of them are suffered from low response and high operation temperature. Ultrathin SnO2 nanosheets with dominant high-energy {001} facets were synthesized by a facile hydrothermal method, and the gas sensing properties to formaldehyde (HCHO) were systemically studied. The structure, morphology, specific surface area, band gap and chemical state of the ultrathin SnO2 nanosheets were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), N2 adsorption–desorption, UV–Vis diffuse reflectance spectrum and X-ray photoelectron spectroscopy (XPS), respectively. Sensors based on SnO2 nanosheets show outstanding gas sensing properties to HCHO vapor at the optimum operating temperature (OOT) of 200 °C. The nanosheet sensor exhibit a response of 207.7 to 200 ppm HCHO at 200 °C with the response-recovery time of 30 s and 57 s, respectively. Notably, as low as 1 ppm HCHO can be readily detected with a high response value (Sr = 6.1). The excellent HCHO sensing performance is mainly originated from the structural sensitization of large specific surface area, characteristically small thickness and dominant high-energy {001} facets.

A novel three-dimensional ball-flower-like g-C3N4/NiO (GN) photocatalyst was firstly fabricated by a simple two-step calcination method for enhanced degradation capability. Our investigation focuses on the construction of p–n heterojunction and specific ball-flower-like structure to overcome limitations of single-component semiconductors, such as low surface area, poor light response and fast recombination of the photogenerated electrons and holes. Detailed photocatalytic experiments revealed that the novel ball-flower-like GN (50%) exhibited much higher activity for the removal of TC and Cr6+ than single g-C3N4, NiO and traditional layered GN. The trapping experiments proved that the superoxide radicals ( $$ ^{ \cdot } {\text{O}}_{2}^{ - } $$ ), holes (h+) and electrons (e−)were the main active species in the photodegradation process. Moreover, three different degradation pathways and fourteen intermediate products of TC were also determined by the LC/MS analysis and these intermediates could be further degraded completely into CO2, H2O, $$ {\text{NH}}_{4}^{ + } $$ , carboxylic acids and any other inorganic intermediates. These results will benefit the fabrication of other 3D p–n heterojunction photocatalysts and their potential application in treatment of organic pollutants.

Recruitment of leukocytes exhibiting arguable and ambiguous processes is involved in the inflammatory response, a specific reaction of organisms to tissue damage. Tracking leukocytes is of great importance for understanding the recruitment of leukocytes. Here, we report the fabrication of carboxyl silane and TAT cell-penetrating peptide-functionalized near-infrared-emitting persistent luminescence nanoparticles (PLNP-TAT) with deep tissue penetration in bioimaging for autofluorescence-free tracking of J774A.1 macrophages homing to inflamed tissues. The PLNP-TAT enables effective labeling of the J774A.1 macrophages and the tracking of the migration of cells to the simulated endothelial inflammatory microenvironment in vitro. Moreover, the PLNP-TAT also allows the tracking of J774A.1 macrophages homing to inflamed tissues in vivo under discontinuous illumination with a red light-emitting diode light. The PLNP-TAT allows in vivo tracking of leukocytes without the need for conventional continuous excitation and offers great potential in cell-tracking and diagnostic applications without the autofluorescence background and thermal damages brought about by continuous excitation.

A novel approach for the fabrication of Short carbon fibers reinforced SiC ceramic composites filaments with core-shell microstructure by direct ink writing was firstly proposed. A novel core-shell feed rod for co-extrusion was designed. Fiber interface layer was prepared by precursor infiltration pyrolysis with polycarbosilane. The results indicated that the ratio (d/D) of carbon fiber (core) to SiC (shell) could be controlled effectively. The debonding and fracture of short fibers with high orientation might improve the fracture resistance of the Cf/SiC composite. The filament-based specimens with strength of ~123 MPa and porosity of ~31% (d/D = 0.6) were successfully fabricated.