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Tissue engineered cardiac patches have great potential as a therapeutic treatment for myocardial infarction (MI). However, for successful integration with the native tissue and proper function of the cells comprising the patch, it is crucial for these patches to mimic the ordered structure of the native extracellular matrix and the electroconductivity of the human heart. In this study, a new composite construct that can provide both conductive and topographical cues for human induced pluripotent stem cell derived cardiomyocytes (iCMs) is developed for cardiac tissue engineering applications. The constructs are fabricated by 3D printing conductive titanium carbide (Ti3C2Tx) MXene in pre-designed patterns on polyethylene glycol (PEG) hydrogels, using aerosol jet printing, at a cell-level resolution and then seeded with iCMs and cultured for one week with no signs of cytotoxicity. The results presented in this work illustrate the vital role of 3D-printed Ti3C2Tx MXene on aligning iCMs with a significant increase in MYH7, SERCA2, and TNNT2 expressions, and with an improved synchronous beating as well as conduction velocity. This study demonstrates that 3D printed Ti3C2Tx MXene can potentially be used to create physiologically relevant cardiac patches for the treatment of MI.

The electrocatalytic reduction of nitrogen (N2) to ammonia (NH3) has broad prospects for green and sustainable NH3 production. Due to the electrocatalytic nitrogen reduction reaction (eNRR) performance of transition metal compound may be restricted with low yield rate, we develop transition metal interface engineering to improve the eNRR performance. Although the edge of MoS2 catalyst is active, the MoS2(0 0 1) surface is inert for N2 electroreduction. Through the hydrothermal and electrodeposition methods, Fe(OH)3 as N2 and H+ channels coated on MoS2 nanosheets array (MoS2@Fe(OH)3/CC) is synthesized. Such catalyst exhibits excellent eNRR performance in 0.1 M Na2SO4 with high Faradaic efficiency (2.76%) and NH3 yield rate (4.23 × 10−10 mol s−1 cm−2) at − 0.45 V (vs. RHE). This work may provide a new electrocatalyst synthesis pathway for artificial N2 fixation. Density functional theory calculations show that electrodeposition Fe(OH)3 can accelerate eNRR process rate of MoS2.

The nitrogen reduction reaction (NRR) has become an ideal alternative to the Haber‐Bosch process, as NRR possesses, among others, the advantage of operating under ambient conditions and saving energy consumption. The key to efficient NRR is to find a suitable electrocatalyst, which helps to break the strong N≡N bond and improves the reaction selectivity. Molybdenum disulfide (MoS2) as an emerging layered two‐dimensional material has attracted a mass of attention in various fields. In this minireview, we summarize the optimization strategies of MoS2‐based catalysts which have been developed to improve the weak NRR activity of primitive MoS2. Some theoretical predictions have also been summarized, which can provide direction for optimizing NRR activity of future MoS2‐based materials. Finally, an outlook about the optimization of MoS2‐based catalysts used in electrochemical N2 fixation are given.

Partial supporting piles removal from deep foundation pit may lead to large-scale foundation pit collapse, resulting in severe consequences. Various studies have investigated the underpinning technology of cutting abutment piles by combining field monitoring and numerical simulation, but there are few studies on cutting supporting piles of foundation pit by the shallow excavation method. Taking an actual deep and large foundation pit as an example, the finite element method (FEM) was adopted to study the surface settlement and the changing trend of the force and displacement of the supporting pile caused by cutting piles during the shallow excavation of double tunnels. The FEM results were verified with the field monitoring data. The simulation results show that the surface settlement around the foundation pit mainly occurs at the pile cutting stage under different excavation sequences (0D, 1D, 2D), and the main distribution area is the one-fold diameter area outside the double tunnel. After the supporting piles are partially cut, the bending moment and displacement of the lower part of the broken piles differ significantly due to different excavation sequences, but the bending moment and displacement of the upper part of the broken piles are basically similar. In the process of removing the supporting piles, the Earth pressure behind the piles is redistributed, and the load is mainly transferred to the adjacent supporting piles outside the tunnel within the radius of one time of the tunnel diameter. However, the load is not evenly transferred to the adjacent supporting piles. Some recommendations for the reinforcement scheme of the supporting structure during cutting supporting piles in deep foundation pit are also proposed. The research results can provide theoretical basis and practical guidance for the construction of similar projects in the future.

Developing non-noble-metal electrocatalyst with efficient and durable activity is a urgent task for addressing the sluggish reaction kinetics of electrochemical water oxidation. Structural evolution of the electrocatalyst is an important strategy for achieving enhanced performance. Herein, in situ evolution of surface Co2CrO4 to CoOOH/CrOOH (CoOOH/CrOOH-Co2CrO4) by an electrochemical method under alkaline conditions was designed for enhancing the electrocatalytic performance of water oxidation. The experiments demonstrated that the synergy between CoOOH/CrOOH and Co2CrO4 resulted in a marked increase in the number of active sites and improved the rate of charge transfer, which enhanced the activity for water oxidation. At a geometrical current density of 20 mA cm−2, the overpotential of the oxygen evolution reaction was 244 mV and the turnover frequency was 0.536 s−1 in 1.0 M NaOH.

A visible-light-driven self-powered photoelectrochemical (PEC) aptasensor was developed for ampicillin (AMP) detecting based on carbon dots (CDs) hybrid MIL-68(In)-derived In2O3 In2S3 hollow tubular heterojunction (CDs/In2O3 In2S3). In2S3 nanosheets uniformly grew in-situ on the surface of In2O3 hollow tubes, forming a close contact heterogeneous interface, which significantly promoted the transfer and separation of photo-generated carriers, and provided a large specific surface area and rich active sites for the PEC aptasensing platform. Furthermore, the CDs/In2O3 In2S3/ITO electrode, which was obtained by dipping assembly, showed remarkable and stable photoelectric signals at zero-bias under visible light irradiation. The amino-functionalized AMP aptamer was fixed on the working electrode as a biological recognition element, and the concentration of AMP was determined by observing the change in photocurrent intensity caused by the specific capture of AMP molecules in solution. Under optimized conditions, the developed PEC aptasensor displayed a relatively wide linear range from 0.001 ng mL−1 to 300 ng mL−1, as well as a low detection limit (LOD) of 0.06 pg mL−1. Besides, the novel self-powered PEC AMP-aptasensor exhibited excellent reproducibility, good stability and selectivity, which open a potential avenue for antibiotic residues detection in environmental media.

In this work, we have successfully in-situ synthesized Na+ and Co2+ co-doped Li0.9Na0.1Mn1-xCoxPO4/C nanoparticles on the surface of Li2.7Na0.3PO4 self-sacrificing template by the co-precipitation process combined with the hydrothermal method. The crystal lattice structure, crystal appearance and electrochemical parameters are characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), galvanostatic charge and discharge test, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). SEM analysis indicates that Li0.9Na0.1Mn0.9Co0.1PO4/C composite shows uniform porous structure and nanosized grain particles. The electrochemical measurements show that the double ions co-doping routine plays a vital influence on the rate capability and electrochemical lithium storage property of LiMnPO4 material. The initial discharge specific capacity of Li0.9Na0.1Mn0.9Co0.1PO4/C reaches 164.3 mAh/g (0.05 C) and 148.0 mAh/g (1 C), respectively. The excellent rate capability is attributed to the synergetic doping effect of Na+ and Co2+ on improving the Li-ion diffusion rate and broadening the Li-ion diffusion channels.

Previous studies have centred on the long-term permanent deformation behaviour of soil under traffic loading while neglecting the dynamic parameters as it is affected by cycle number. In this study...

A novel ratiometric electrochemical (EC) sensing platform was established for sensitive immunoassay of target cytokeratin 19 fragment 21-1 (CYFRA21-1) biomarker by combining competitive immunoreact...

The catalytic reduction performance of NO on the surface of Fe-doped ZnAl2O4 (100) was calculated based on DFT. The adsorption of NO and other molecules, the change of reaction energy of CH4 and C2H4 as reducing agents, and the activation energy barrier of CH4 were studied. It was found that the best adsorption energy of NO is −2.166 eV. Compared with Al and Zn sites, doped Fe atoms are better adsorption catalytic sites. At temperatures of 300 K and 600 K, the molecules will move in the direction of the Fe atoms. O2 adsorption will repel NO, reduce its adsorption energy, and cause NO to lose electrons and be oxidized. The reaction enthalpy with CH4 as the reducing agent is −7.02 eV, and with C2H4 is −3.45 eV. Transition state calculations show that O reduces the dissociation barrier of CH4 by about 2 eV. The smaller adsorption energy and negative reaction enthalpy of the product indicate that the iron-doped ZnAl2O4 has a good catalytic NO potential. This also provides a basis for future research on the catalytic mechanism of different hydrocarbons.

Electrocatalytic nitrogen reduction reaction (NRR), as a green and sustainable method for ammonia synthesis, has become one of the candidates to substitute industrial Haber-Bosch ammonia synthesis in the near future. In this work, gold nanoparticles (Au NPs) were successfully anchored on bismuth sulfide nanorods (Bi

This study proposes a competitive photoelectrochemical (PEC) immunosensor for detecting diethylstilbestrol (DES). The PEC sensing platform uses a zinc and molybdenum codoped BiVO4 nanoarray ((Zn,Mo):BiVO4) as the photoactive matrix and manganese hexacyanoferrate hydrate loading silicon dioxide layer composite nanocubes (MHCF@SiO2 NCs) as the signal quencher. The (Zn,Mo):BiVO4 nanoarray demonstrated brilliant PEC behavior, by virtue of the local electric field formed by the codoped Zn and Mo. This doping accelerated the electron transfer and improved the photoelectric conversion efficiency in BiVO4 nanoarray under visible light. Furthermore, the nanoarray structure with its large surface area provided abundant binding sites for the immune response. As the MHCF@SiO2 NCs-anti-DES competitively bonded with either free DES or bovine serum albumin conjugated DES (BSA-DES), hydrogen peroxide (H2O2) as electron donor was competitively consumed and meanwhile steric resistance blocked electrons transfer. For the above reasons, the photocurrent signal was reduced. Thus, the standard sample free DES was accurately detected, and the fabricated PEC immunosensor displayed an outstanding photocurrent response from 0.1 pg/mL to 50 ng/mL with a detection limit of 0.05 pg/mL. Simultaneously, the acceptable stability, selectivity, and reproducibility of the designed dual-competitive sensing platform suggest its applicability to small molecule detection.

In this work, a triple-amplified biosensor with a bioactivity-maintained peculiarity was constructed for quantitative procalcitonin (PCT) detection. As everyone knows, a strong electrochemiluminescence (ECL) signal is the premise to ensure high sensitivity for trace target detection. Hence, a valid tactic was developed to achieve signal amplification of luminophor by using Co2+-based metal-organic frameworks (ZIF-67) and silver-cysteine (AgCys). The ZIF-67 particles, which have more atomically dispersed Co2+, could play the role of a co-reaction accelerator to catalyze S2O82- to generate abundant Co3+ and sulfate radical anions (SO4•-). Afterward, a mass of Co3+ was reduced to more hydroxyl radicals (OH•) by H2O, thus ulteriorly reducing S2O82- to generate more SO4•-. Remarkably, S2O82- was reduced to SO4•- continuously with the recycling of Co2+ and Co3+, which realized an effective signal amplification. Meanwhile, the AgCys complex with superior catalysis and biocompatibility was prepared to further improve the ECL signal and maintain the bioactivity of the biomolecule. Furthermore, HWRGWVC, a heptapeptide that was used for combining the Fc fragments of an antibody by Au-S bonding to achieve the fixed point fixation, could not only maintain bioactivity of an antibody but also improved its incubation efficiency, thus further enhancing biosensor sensitivity. Under optimum conditions, the proposed biosensor realized highly sensitive assay for PCT with a wide dynamic range from 10 fg/mL to 100 ng/mL and a detection limit as low as 3.67 fg/mL. With superior stability, selectivity, and repeatability, the prepared biosensor revealed immense potential application of ultrasensitive assay for PCT in human serum.

Insulated tubular busbar is a new type of current-carrying equipment with excellent performance. However, the research on this equipment is insufficient because of the short application and the lack of technical digestion, which has resulted in many accidents. In this paper, the full-scale model of epoxy-impregnated-paper insulated tubular busbar with bubble defects was designed and produced, its electrical breakdown process was investigated by withstand voltage test. In the experiment, the failure mode of breakdown caused by gas expansion was found for the first time. The research showed that the electrical-mechanical breakdown process could be divided into two stages: gas increase stage and breakdown threshold stage. The research also obtained the characteristics and the change criterions of the two stages. The gas in the bubble defects generated from epoxy decomposition which caused by partial discharge. When the gas pressure exceeds the critical fracture toughness of the bubble defects wall, the unstable crack extension occurs, therefore, improving the ability about resistance to partial discharge of epoxy resin or improving the fracture toughness of epoxy resin by modifying would enhance the breakdown performance of insulated tubular busbar. The result also has reference significance for other epoxy-impregnated-paper insulated electrical equipment.

Herein, a smart competitive-type photoelectrochemical (PEC) sensor based on an antigen-down (Ag-down) format for procalcitonin (PCT) detection is proposed. A fullerene sensitized flower-like Sn3O4 nano-structure is used as the photoactive platform, and FeS2 is labeled on the secondary antibody as a signal adjusting element. The sensor exhibits excellent sensitivity and great stability.

Zinc(II) tetraphenylporphyrin (ZnTPP) has very broad application prospects in the fields of supramolecular chemistry, solar cells and nanomaterials. In this paper, by using scanning tunneling microscopy (STM), we systematically investigated the ZnTPP molecule and its four derivatives formed by thermal annealing were characterized unambiguously by bond-resolved STM (BR-STM). The electronic properties of the ZnTPP molecule and its four cyclodehydrogenation products were investigated by scanning tunneling spectroscopy (STS) combined with DFT calculations. The spatial distribution of molecular frontier orbitals of four products was obtained by dI/dV mappings. This work gives rise to a full-scale investigation of ZnTPP on Au(111), which will be potentially useful in nanodevices and optoelectronics.

The aim of this study was to reveal the macroscopic and mesoscopic deterioration behaviors of concrete under the coupling effect of chlorine salt erosion and the freezing–thawing cycle. The rapid freezing–thawing test was carried out in a 5% chlorine salt environment. The macroscopic characteristics of concrete were analyzed by testing the mass, the relative dynamic modulus of elasticity, and the compressive strength of concrete under different freezing–thawing cycles. Using CT scanning technology and three-dimensional reconstruction technology, the pore structure, CT value, and surface deviation of concrete before and after freezing–thawing were analyzed. Based on the changes of solid volume, pore volume, and solid CT value of concrete, the calculation method of relative CT value was proposed, and the damage model was established with relative CT value as the damage variable. The results demonstrate that the mass loss rate decreases in the beginning and then increases in the process of chlorine salt erosion and freezing–thawing, and the smaller the concrete size, the greater the mass loss rate. The relative dynamic modulus of elasticity decreases gradually, slowly at the initial stage and then at a faster rate, and the compressive strength loss rate increases gradually. The pore quantity, porosity, and volume loss rate of concrete increase in a fluctuating manner, whereas the relative CT value decreases. The comprehensive analysis shows that the chlorine salt frost resistance of concrete is negatively related to the water-cement ratio when the freezing–thawing cycle is fixed. The damage model could better reflect the freezing–thawing damage degree of concrete with different water cement ratios, and the damage evolution process is well described by the Weibull function.

Cardiomyocytes (CMs) and fibroblast cells are two essential elements for cardiac tissue structure and function. The interactions between them can alter cardiac electrophysiology and thus contribute to cardiac diseases, such as arrhythmogenesis. One possible explanation is that fibroblasts can directly affect cardiac electrophysiology through electrical coupling with CMs. Therefore, detecting the electrical activities in the CM-fibroblast network is vital for understanding the coupling dynamics among them. Current commercialized platforms for studying cardiac electrophysiology utilize planar microelectrode arrays (MEAs) to record the extracellular field potential (FP) in real-time, but the prearranged electrode configuration highly limits the measurement capabilities at specific locations. Here, we report a custom-designed MEA device with a novel micropatterning method to construct a controlled network of neonatal rat CMs (rCMs) and fibroblast connections for monitoring the electrical activity of rCM-fibroblast co-cultures in a spatially controlled fashion. For the micropatterning of the co-culture, surface topographical features and mobile blockers were used to control the initial attachment locations of a mixture of rCMs and fibroblasts, to form separate beating rCM-fibroblast clusters while leaving empty space for fibroblast growth to connect these clusters. Once the blockers are removed, the proliferating fibroblasts connect and couple the separate beating clusters. Using this method, electrical activity of both rCMs and human-induced-pluripotent-stem-cell-derived cardiomyocytes (iCMs) was examined. The coupling dynamics were studied through the extracellular FP and impedance profile recorded from the MEA device, indicating that the fibroblast bridge provided an RC-type coupling of physically separate rCM-containing clusters and enabled synchronization of these clusters.

This research put forward a novel split-type electrochemical (EC) immunosensor which integrated the controlled-release strategy with EC detection for application in the field of biosensing. Concretely, ascorbic acid (AA) was packaged in a cadmium sulfide (CdS)-capped spherical mesoporous bioactive glass (SBG) nanocarrier (SBGCdS) on account of encapsulation technology. To reduce the complexity of the bioanalysis, the detection antibody-labeled SBGCdS-AA bioconjugate was applied in a 96-well microplate for the immunoreaction process, which is independent of the EC determination procedure. Thus, the immune interference and steric hindrance caused by the accumulation of nanomaterials on the electrode could be minimized. Subsequently, AA was released efficiently via the destruction effect of dithiothreitol on the disulfide bond. In addition, for the as-prepared FcAI/l-Cys/gold nanoparticles (GNPs)/porous BiVO4 (p-BVO)/ITO EC sensing platform in the detection solution, the synergetic catalysis of Fc and GNPs/p-BVO toward the oxidation of the released AA could be realized, which triggered AA-mediated significant signal magnification throughout this study. In particular, p-BVO with an ordered nanoarray structure could accelerate the electron transfer to assist in sensitivity improvement of this system. This novel biosensor was capable of assaying the neuron-specific enolase (NSE) biomarker sensitively, from which a linear range of 0.001-100 ng/mL was derived along with a low detection limit of 1.08 pg/mL. An innovative way could be paved in the bioanalysis of NSE and other biomarkers.

The design and synthesis of highly efficient and durable non-noble metal electrocatalysts have become a top priority for the hydrogen evolution reaction (HER). Thus, this study describes a straightforward synthesis of nickel-doped cobalt phosphide nanowire clusters on carbon cloth (Ni-CoP/CC) via a simple hydrothermal-phosphating process. Owing to the unique nanowire cluster structure together with the use of current collector, such binder-free three-dimensional electrode of Ni-CoP/CC displays efficient HER activity, achieving the low overpotential of 53 mV at a geometric current density of 10 mA cm−2, with a Tafel slope of 57 mV dec−1 and superior stability (100 h) in 1.0 M KOH.

Nowadays, the electrochemiluminescence (ECL) immunosensor with the unique superiority of tunable luminescence and ultrahigh sensitivity has become one of the most promising immunoassay techniques, especially for low-abundance biomarkers analysis. However, the use of signal probes with high excited potential and applied emitters which owned good intensity but biotoxicity limited its application. Herein, an ECL resonance energy transfer strategy was developed based on protein bioactivity protection utilizing europium-doped phosphoric acid gadolinium (GdPO4:Eu) as novel low-potential luminophor (donor) and Pd@Cu2O as the quenching probe (acceptor). Specifically, GdPO4:Eu was first prepared by using the hydrothermal synthesis method to apply in ECL, and when it coexisted with K2S2O8, cathode, a strong ECL signal would be generated at a low potential of -1.15 V (vs Ag/AgCl), where the immunocompetence of antigens and antibodies can be maintained well. Electrical pair Eu3+/Eu2+, as the coreactant promoter, produced by potential excitation could produce more SO4•- to accelerate the oxidation process of GdPO4:Eu. Meanwhile, Cu2O coated onto Pd (Pd@Cu2O), as a dual-quencher, enhanced the quenching effect of Pd alone and controlled the ECL intensity of the "signal on" state within a reasonable range. As a result, the proposed biosensor for detection of trace procalcitonin, a biomarker of systemic inflammatory response syndrome, exhibited a far low detection limit, 0.402 fg/mL (S/N = 3). Importantly, this work not only utilized a promising ECL emitter for biosensing platform construction but also had momentous potential in biomarker detection of disease diagnosis and clinical analysis.

Surface-enhanced Raman spectroscopy (SERS) has emerged as an ultrasensitive molecular-fingerprint-based technique for label-free biochemical analysis of biological systems. However, for conventional SERS substrates, SERS enhancement factors (EFs) strongly depend on background refractive index (RI), which prevents reliable spatiotemporal SERS analysis of living cells consisting of different extra-/intracellular organelles with a heterogeneous distribution of local RI values between 1.30 and 1.60. Here, we demonstrate that nanolaminated SERS substrates can support uniform arrays of vertically oriented nanogap hot spots with large SERS EFs (>107) insensitive to background RI variations. Experimental and numerical studies reveal that the observed RI-insensitive SERS response is due to the broadband multiresonant optical properties of nanolaminated plasmonic nanostructures. As a proof-of-concept demonstration, we use RI-insensitive nanolaminated SERS substrates to achieve label-free Raman profiling and classification of living cancer cells with a high prediction accuracy of 96%. We envision that RI-insensitive high-performance nanolaminated SERS substrates can potentially enable label-free spatiotemporal biochemical analysis of living biological systems.

An accurate characterization of intra- and inter-laminar damage is essential for the prediction of the damage onset and evolution in composite laminates. This paper presents a discrete crack-informed 3D continuum damage mechanics (CDM) model and its application for the simulation of delamination migration in tape laminates. The proposed approach aims at capturing the initiation and propagation of discrete matrix cracks and their interactions with interface delaminations without introducing a physical crack along with its explicit front tracking. The 3D Hashin failure criteria are employed first to predict the damage initiation of composite materials under an arbitrary stress state. A crack orientation-dependent damage evolution model is developed to dictate the composite stiffness degradation associated with a matrix crack plane. The matrix crack plane is parallel to the fiber direction and its orientation is determined by the maximum principal stress in the transverse plane. The corresponding matrix crack-informed stiffness is degraded based on the orientation of the crack plane. To alleviate mesh dependency within a continuum damage modeling framework, an energy-driven failure mechanism is adopted for characterizing damage evolution of matrix cracking and fiber breakage. By coupling the discrete crack informed model for intra-laminar damage prediction and the cohesive model for interface delamination within the same CDM framework, their synergistic interaction can be captured during the progressive failure analysis of composite laminates. The predictive capability of the enhanced modeling strategy is examined through its application of a delamination migration problem with the presence of the delamination initiation and migration via matrix cracking. The matrix cracks and delamination growths are captured for different loading positions without a pre-assumption on the failure mode. Good agreement is achieved by comparing the predictions with the experimental data from a published NASA report.

This paper presents a physics-based prediction of crack initiation at the microstructure level using the phase field (PF) model without finite element discretization, coupled with an efficient and accurate modeling of crack propagation at macro-scale based on extended finite element method (XFEM). Although the macro-scale model assumes linear elastic material behavior, at micro-scale the behavior of plastically deforming heterogeneous polycrystals is taken into account by coupling the PF model and a crystal plasticity model in the fast Fourier transform computational framework. A sequential coupling has been established for the multiscale modeling where the macro-scale finite element (FE) model determines the hot spots at each cyclic loading increment and passes the associated stress/strain values to the unit-cell phase-field model for accurate physics-based microstructure characterization and prediction of plasticity induced crack initiation. The PF model predicts the number of cycles for the crack initiation and the phenomenological crack growth models are employed to propagate the initiated crack by the appropriate length to be inserted in the FE mesh. Finally, the XFEM solution module is activated to perform mesh independent crack propagation from its initial crack size to the final size for the total life prediction. The effectiveness of the proposed multiscale method is demonstrated through numerical examples.

In this work, 3,4,9,10-perylenetetracar-boxylic acid (PTCA) as luminophor was grafted on the surface of graphene oxide (PTCA-GO) directly. GO exhibited large specific surface area and excellent electrical conductivity which can immobilize large amounts of PTCA to improve the electrochemiluminescence (ECL) efficiency. Moreover, gold nanoparticles (Au NPs) were anchored on the surface of PTCA-GO to immobilize primary antibodies (Ab1) via Au-NH2 bond and enhance the electron transport of PTCA-GO. CuS was used as a novel co-reaction accelerator in PTCA-K2S2O8 system to label secondary antibodies (Ab2), which can react with the coreactant (K2S2O8) to produce more SO4•-. SiO2 nanospheres with large specific surface area were used to load a mass of CuS and Au NPs, which can directly combine with Ab2 and accelerate the ECL emission remarkably. Therefore, a novel sandwich-type ECL immunosensor was fabricated successfully for amyloid-β protein (Aβ) detection. Under the optimal condition, a wide detection range from 50 fg/mL to 25 ng/mL and a low detection limit of 18 fg/mL (S/N = 3) were obtained. Featuring favorable specificity, stability and reproducibility, the strategy can be a powerful analytical tool in sensitive trace detection of biomolecules in clinical analysis.

In this work, the heterostructures of Au nanoparticles loaded on 3D flower-like α-Fe2O3 (Au NPs/α-Fe2O3) as a platform and core-shell CdSe@CdS quantum dots sensitized graphene oxide (GO/CdSe@CdS QDs) as a signal amplification label were established in an ultrasensitive sandwich-type photoelectrochemical (PEC) immunosensor based on the "signal-on" type amplification method for detection of amyloid β-protein (Aβ). Specifically, the ultrahigh sensitivity of the proposed immunosensor came from two main properties. First, Au NPs/α-Fe2O3 could partially absorb visible-light, which dramatically promotes electron transfer because of the excellent conductivity of Au NPs, and effectively inhibits the electron-hole recombination, thanks to the effect of heterostructures. Second, the signal-on type is based on the signal amplification label of GO/CdSe@CdS QDs which on adequate absorption of visible-light can improve generation of photogenerated electron-hole pairs effectively. Under optimal conditions, the well-prepared PEC immunosensor exhibited a low detection limit of 0.02 pg mL-1 and a wide linear range from 0.06 pg mL-1 to 350 ng mL-1 for Aβ detection. Meanwhile, it also presented good reproducibility, specificity, and stability and might open a new promising pathway for detection of other important biomarkers.

The development of effective non-noble metal based catalysts for the electrocatalytic oxygen evolution reaction (OER) at lower overpotentials has attracted tremendous attention due to its important role for various electrochemical energy storage and conversion devices. Transition metal based oxides have been deeply investigated, benefiting from their promising catalytic activity as well as their low cost. However, among these oxides, the OER efficiency of molybdenum oxides has rarely been studied due to its limited intrinsic activity. Herein, we reported amorphous cobalt-doped molybdenum oxide (Co–MoOx) with a core–shell structure as an effective OER catalyst for the first time. Benefiting from the cobalt doping as well as the amorphous structural character, the charge transfer process and the active sites are both well optimized, which is highly desired for an advanced electrocatalyst. As expected, the Co–MoOx catalyst afforded an extremely low overpotential of 340 mV at a current density of 10 mA cm−2, and a small Tafel slope of 49 mV dec−1 in KOH solution. This work shows an effective strategy for the realization of highly efficient OER electrocatalysts.

The Haber-Bosch process for the synthesis of ammonia (NH3) not only causes large energy consumption but also leads to CO2 emissions. Electrocatalytic hydrogenation of N2 to NH3 under ambient conditions is a highly desirable alternative method; however, it needs an efficient electrocatalyst. In this study, we report a mesoporous boron nitride (MBN) metal-free electrocatalyst for the N2 reduction reaction under ambient conditions. Owing to its mesoporous structure, this MBN electrocatalyst can expose more active sites, resulting in an outstanding NH3 formation rate of 18.2 μg h-1 mgcat.-1 with a faradaic efficiency of 5.5% at -0.7 V vs. reversible hydrogen electrode in 0.1 M Na2SO4. It also demonstrates strong long-term electrochemical durability.

The synthesis of NH3 is mainly dominated by the traditional energy-consuming Haber–Bosch process with a mass of CO2 emission. Electrochemical conversion of N2 to NH3 emerges as a carbon-free process for the sustainable artificial N2 reduction reaction (NRR), but requires an efficient and stable electrocatalyst. Here, we report that the Mo2C nanorod serves as an excellent NRR electrocatalyst for artificial N2 fixation to NH3 with strong durability and acceptable selectivity under ambient conditions. Such a catalyst shows a high Faradaic efficiency of 8.13% and NH3 yield of 95.1 μg h–1 mg–1cat at −0.3 V in 0.1 M HCl, surpassing the majority of reported electrochemical conversion NRR catalysts. Density functional theory calculation was carried out to gain further insight into the catalytic mechanism involved., Mo2C nanorods act as an electrocatalyst for artificial N2-to-NH3 conversion with good durability at ambient conditions. They achieve a high FE of 8.13% and NH3 yield of 95.1 μg h−1 mg−1 in 0.1 M HCl.

PURPOSE To evaluate the stress distribution during chewing in a realistic loading condition on a prosthesis (single-tooth crown) using a static analysis. MATERIALS AND METHODS An all-ceramic crown in the mandibular first molar was selected as the representative prosthesis. First, three contact states (intrusive state, transition state, and extrusive state) were selected from the parametric chewing trajectory. Then, the distances between the antagonistic molars and the normal vectors of the mandibular first molar were calculated by using an automated contact analysis routine (independently developed). Next, normal and tangential forces were defined based on the contact information and the food property. Finally, the static analysis was executed by applying the force and the fixed boundary condition. RESULTS The distribution of the occlusal force was nonuniform in the static analysis. Compared to concentrated and uniform loading conditions, the stress distribution of the prosthesis under the nonuniform loading condition revealed new characteristics. CONCLUSION The generation procedure of the static analysis, based on fundamental contact analysis, was evidence-based. The static analysis with the nonuniform loading condition was more recommended than the other two conditions.

A novel electron donor controlled-release system is proposed based on liposome encapsulated L-cysteine for the sensitive determination of cytokeratin 19 fragment 21–1 (CYFRA 21-1). On the one hand, a defective TiO2 modified with methylene blue was employed as a photoactive platform which exhibited a high photoelectrochemical (PEC) response owing to the introduction of oxygen vacancies and the high photosensitivity of the dye. On the other hand, L-cysteine as the sacrificial electron donor was encapsulated in the vesicles of liposomes, and this composite was used as the signal amplification factor, which is labeled on the secondary antibody of CYFRA 21-1 to further improve the photocurrent sensitivity. The excellent electron transfer path in photoactive materials coupled with the skilful electron donor controlled-release system, contributed to the sensitive PEC analysis of CYFRA 21-1 underoptimum conditions. The PEC immunoassay showed a linear current response in the range 0.0001–100 ng/mL with a detection limitof 37 fg/mL. Enhanced stability and satisfactory reproducibility were also achieved. The proposed concept provides a novel signal-on strategy for the sensitive detection of other cancer markers in the electrochemical sensing field.

Shock waves have shown a promising application in biomedical membranes. What needs to be noticed is that a shock wave will cause damage to human tissues when it is too strong. The damage to dipalmitoylphosphatidylcholine membranes induced by shock waves was studied by adopting all-atom molecular dynamics. It was found that as the impulse increased, the membrane became increasingly disordered and the folds became more severe with more water molecules in the hydrophobic area. The membrane impact process was divided into three stages, namely, the shock stage, recovery stage, and aftereffect stage. It was observed that the membrane damage was recoverable during the impact when the impulse was less than 127 mPa s, but no membrane damage recovery was observed when the impulse was greater than 153 mPa s. Furthermore, with the impulse increasing, the maximum strain of the membrane also increased, which was linear with the impulse. Moreover, when the impulse was 153 mPa s, the maximum strain of the membrane turned to 0.34. After the shock simulations, the recovery simulations continued for a few nanoseconds, and it was found that all of the membranes recovered.

Self-supported Fe3N-Co2N nanoarray with high electric conductivity and large surface area was prepared for growth of MIPs and further constructing a sensitive and stable electrochemical sensor. For the evaluation of its performance, Fe3N-Co2N is used as sensing electrode material, and AMP is used as template molecule to construct the MIP electrochemical sensor. Under the optimized conditions, the developed MIPs electrochemical sensor detects AMP with a low detection limit of 3.65 × 10−10 mol L−1 and shows outstanding reproducibility and stability. When the MIPs electrochemical sensor was applied to detect AMP in milk samples via standard addition method, the recovery within 97.06–102.43% with RSD of 1.05–2.11% was obtained. The fabrication of MIPs electrochemical sensor is highly promising for sensitive and selective electrochemical measurement and food safety testing. This work can provide theoretical guidance for truly challenging problems.

No-wash detection of small molecules in real samples has been attracting attention in the field of sensors including electroanalytical biosensors. Based on the direct electrochemical oxidation of fluorene-9-bisphenol (BHPF) on a CoN nanoarray electrode, we developed a ratiometric molecularly imprinted polymeric electrochemical (MIP-EC) sensor to realize no-wash detection of BHPF in serum and tap water. The CoN nanoarray in situ grown on carbon cloth (CC) served as the working electrode, which could load the electroactive toluidine blue (TB) and be modified by the MIPs. As the MIP concentration on the modified electrode surface was increased, the amount of BHPF exposed on the electrode surface increased and the amount of exposed TB decreased. Thus, the values of ΔITB and ΔIBHPF decreased and increased, respectively, with an increasing amount of BHPF. Therefore, a ratiometric strategy was established by using the value of ΔITB/ΔIBHPF as the instruction response to realize detection of BHPF with high sensitivity and reliability. The developed ratiometric MIP-EC sensor showed strong anti-interference ability, good detection reproducibility and stability towards no-wash detection of BHPF as shown from tests with real samples. This work can further provide theoretical and practical guidance for the detection of other familiar small molecules.

This paper discusses the deformation mechanism of a utility tunnel crossing active ground fissures in Xi’an as observed in a physical model test. The purpose of this work is to confirm the precise effects of ground fissures on utility tunnels. The physical simulation experiment is carried out to measure the earth pressure and the strain relationship of the structure and the structural displacement. The structure appears to have been destroyed by torsion. The structural deformation located in the tunnel’s footwall was more serious than that in the hanging wall. However, at the top of the utility tunnel structure, the earth pressure in the footwall was less than that in the hanging wall. The increased range of the hanging wall at 0.3–1.5 m (the prototype within the range of 22.5 m) and decreased range of the footwall at 0.3–0.8 m (the prototype within the range of 12 m) were basically consistent with changes in the contact pressure at the structure’s bottom. This was roughly consistent with the main deformation zone of ground fissures mentioned in the specification, with the hanging wall at 0–20 m and footwall at 0–12 mm. Displacement meter data shows that the structure tends to deform to the lower right as the utility tunnel is “twisted” clockwise. These observations mark a notable departure from the previously published failure mode of metro tunnels under active ground fissures.

In present work, the three-dimensional transient heat transfer equation for a fiber metal laminated (FML) plate is established, and temperature field under dual-ellipse distribution laser processing is obtained through the Newton-Cotes method. Then the three-dimensional constitutive equations are derived, and the transient thermodynamic governing equations are obtained based on the Hamilton variational principle subsequently. Finally, the finite difference method and Newmark method are utilized to solve the thermodynamic equations in both space and time domains, respectively. The research aims at studying three-dimensional thermodynamic behaviors for a FML structure subjected to dual-ellipse distribution laser heat source and giving the effects of Fourier series term, finite difference point, aspect ratio, fiber arrangement angle and laser moving speed on the thermodynamic behaviors for the FML structure.

NH3 synthesis consumes 1% of the world’s energy, making it a substantial contribution to greenhouse gas emissions. Electrochemical artificial N2 fixation provides a green and sustainable route over the traditional Haber–Bosch process to enable sustainable NH3 synthesis at ambient conditions while requiring catalysts for the N2 reduction reaction (NRR). Here, we first demonstrate that the Y2O3 nanosheet serves as a high-efficiency nonprecious metal NRR catalyst. When tested at neutral pH, such Y2O3 nanosheet attains a large NH3 yield of 1.06 × 10–10 mol s–1 cm–2 and a high Faradaic efficiency of 2.53% at −0.9 V vs reversible hydrogen electrode with excellent stability and durability. Density functional theory calculations reveal that addition of the first H atom is the potential crucial step, the following hydrogenation steps are feasible, and it is easy to release NH3 molecules.

The accurate and rapid detection of cardiac troponin I (cTnI) at an early stage can prevent people from getting acute myocardial infarction to a great extent. Here, an ultrasensitive sandwich-type electrochemical immunosensor for the quantitative detection of cTnI is designed based on a novel signal amplification strategy. Gold nanoparticles (Au NPs) doped covalent organic frameworks (COFs) and electron mediator toluidine blue (TB-Au-COFs) behave as labels for achieving signal amplification. Note that polypyrrole modified titanium dioxide nanoparticles (TiO2-PPy) with a high electronic conductivity and a large specific surface area can promote the performance of the immunosensor. For the immobilization of primary antibodies, Au NPs decorated TiO2-PPy (TiO2-PPy-Au) is used as the substrate material to improve electron transfer. The proposed method exhibits a linear range from 0.5 pg mL−1 to 10.0 ng mL−1 and a low detection limit of 0.17 pg mL−1 (S/N = 3). The immunosensor exhibits good stability, acceptable reproducibility and accuracy, indicating potential applications in clinical diagnostics.

The interaction between the high-energy particles in the plume and the spacecraft surfaces will produce interference torque that affects the operating state of the spacecraft in orbit. The thrust of an electric propulsion system is quite small, so it is difficult to be measured directly. The Vacuum Plume Laboratory (VPL) measured the LIPS-200 type ion thruster plume force in an order of 10 − 3 N using a fully elastic micro thrust measuring device. In this paper, the particle in cell (PIC) method and the direct simulation Monte Carlo (DSMC) method are employed to analyze the three-dimensional plasma environments under specified experimental conditions. The Maxwell model is used to calculate the plume force on a 300 mm diameter plate. Simulation results of the plume force give good agreements with the experimental data. Moreover, the effects of the 300 mm diameter aluminium plate on the flow field in vacuum conditions are analyzed. The results show that the number density of atoms is greatly increased before the plate, which has a further impact on the distribution of charge exchange ions (CEX). The enhanced CEX ions moving towards the solar battery panels or sensitive optical components may cause possible damage or interference, which should be avoided by the designers.

Here, we report a rapid and low-cost live/dead assay for bacteria in aqueous samples via a dielectrophoresis (DEP) technique employed in a microfluidic platform. The platform has reusable compartment housing the microelectrodes for DEP activation and bioimpedance sensing. The disposable compartment contains the sample inlet and outlet and the microfluidic channel for sample analysis. The chip has an array of insulating pillars for generating DEP forces on bacteria and a focusing region for enhanced impedance signal. The DEP force is utilized to enrich bacteria and selectively release them by tuning the frequency of the applied electric field. An algorithm is implemented to determine the concentration of live bacteria in the mixture by analyzing the magnitude and duration of the measured impedance. The chip performance was validated by analyzing various ratios of live/dead bacteria and was compared with parallel flow cytometry experiments. [2018-0100]

NH3 serves as an attractive hydrogen storage medium and a renewable energy sector for a sustainable future. Electrochemical reduction is a feasible ambient reaction to convert N2 to NH3, while it needs efficient electrocatalysts for the N2 reduction reaction (NRR) to meet the challenge associated with N2 activation. In this Letter, we report on our recent experimental finding that the TiO2 nanosheets array on the Ti plate (TiO2/Ti) is effective for electrochemical N2 conversion to NH3 at ambient conditions. When tested in 0.1 M Na2SO4, such TiO2/Ti attains a high NH3 yield of 9.16 × 10-11 mol s-1·cm-2 with corresponding Faradaic efficiency of 2.50% at -0.7 V vs reversible hydrogen electrode, outperforming most reported aqueous-based NRR electrocatalysts. It also shows excellent selectivity for NH3 formation with high electrochemical stability. The superior NRR activity is due to the enhanced adsorption and activation of N2 by oxygen vacancies in situ generated during electrochemical tests.

Transition-metal phosphides have been intensively and extensively studied as earth-abundant catalysts for effective hydrogen evolution electrocatalysis, but it is highly desired to explore a new st...

The development of efficient earth-abundant electrocatalysts for N2 reduction to ammonia (NH3) under ambient conditions is critical for achieving a low-carbon and sustainable-energy society. Herein, we report the development of VN nanosheet array on Ti mesh as an active and selective electrocatalyst for N2 reduction reaction (NRR) in acid at room temperature and atmospheric pressure in 0.1 M HCl. A rate of NH3 formation of 8.40 × 10–11 mol s–1 cm–2 is obtained at −0.50 V with a Faradaic efficiency of 2.25%. Notably, such catalyst material also exhibits high selectivity (no formation of N2H4) and electrochemical stability. Theoretical and experiment results suggest that VN catalyzes NRR via a Mars–van Krevelen mechanism. This study would offers the potential of utilization of attractive 3D catalyst electrode toward efficient NH3 synthesis for applications.

Electrochemical N2 reduction reaction (NRR) under ambient conditions offers us an environmentally friendly route for artificial synthesis of NH3. However, up to now, few noble-metal-free electrocatalysts with satisfactory catalytic activities have been explored. In this Letter, we demonstrate that MoN nanosheets array on carbon cloth (MoN NA/CC) acts as a high-performance NRR electrocatalyst toward NH3 electrosynthesis in 0.1 M HCl under ambient conditions. This catalyst achieves a large NH3 yield of 3.01 × 10–10 mo1 s–1 cm–2 and a Faradaic efficiency of 1.15% at −0.3 V vs reversible hydrogen electrode with strong electrochemical durability and selectivity. Density functional theory calculations reveal that MoN NA/CC catalyzes NRR via the Mars–van Krevelen mechanism.

It is attractive to develop an effective bifunctional electrocatalyst for full water splitting. In this Letter, we report that a NiWO4 nanowire array on a Ti mesh (NiWO4/TM) is a high-performance a...

Electrolytic hydrogen generation needs efficient and durable electrocatalysts for the hydrogen evolution reaction. In this Letter, for the first time, we report on the development of P-doped Ag nanoparticles embedded in N-doped carbon nanoflake (denoted as “P-Ag@NC”) for effective hydrogen evolution electrocatalysis. When tested in 0.5 M H2SO4, such P-Ag@NC demands overpotential of only 78 mV to drive a catalytic current density of 10 mA cm–2, which is 198 mV less than that of Ag@NC counterpart. Remarkably, this catalyst also shows strong long-term electrochemical durability with the preservation of its catalytic activity for at least 85 h. Density functional theory calculations suggest that P doping brings the optimization of hydrogen adsorption free energy to a more thermo-neutral value.