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Based on the combined finite–discrete element method (FDEM), this paper presents a moisture diffusion–fracture coupling model to simulate soil desiccation cracking. The coupling model, firstly, analyzes moisture content distribution within the soil according to a moisture diffusion model. Then, the shrinkage stress caused by the change of moisture content is calculated and applied to the system equation of FDEM. Finally, if a new crack is generated, the node sharing relationship and mesh of adjacent solid elements are updated for moisture diffusion calculation in the next time step. In this paper, examples of 1D moisture migration in the soil trip, shrinkage stress and deformation caused by the moisture reduce in the rectangular soil are studied. The simulation results agree well with analytical solutions, which verifies the correctness of the proposed model. Then, the model is used to simulate soil desiccation cracking process, and the crack evolution pattern in the numerical results is consistent with experimental results. Besides, several main factors affecting soil desiccation cracking are also investigated, including the elastic modulus, the moisture shrinkage coefficient, and the soil thickness. The moisture diffusion–fracture coupling model provides a new research tool for studying the mechanical mechanism of soil desiccation cracking.

Molecules in confined spaces exhibit unusual behaviors that are not typically observed in bulk systems. Such behavior can provide alternative strategies for exploring new reaction pathways. Cleavage of the C=N bond of Nile red (NR) in solution is an irreversible reaction. Here, we used spatial confinement within a cationic micelle-confined system to convert this reaction to a reversible process. The fluorescence of NR shifted between red and green for nine cycles. The new chemical pathway based on spatial confinement can be attributed to two factors: increasing the local concentration of reactants and reducing the reaction energy barrier. This effect is supported by both experimental evidence and theoretical calculations. The cross-linked silica shell comprising the confinement chamber stabilizes the enclosed molecules. This reduces fluorophore leakage and maintains fluorescence intensity in most environments, including in solution, on paper, and in hydrogel films, and expands practical applications in encrypted information and multi-informational displays.

The diffusion of target analytes is a determining factor for the sensitivity of a given gas sensor. Surface adsorption results in a low-concentration region near the sensor surface, producing a concentration gradient perpendicular to the surface, and drives a net flux of molecules toward solid reactive reagents on the sensor surface, that is, vertical diffusion. Here, organic semiconductor supramolecules were patterned into micromeshed arrays to integrate vertical and horizontal diffusion pathways. When used as a gas sensor, these arrays have an order of magnitude higher sensitivity than traditional film-based sensors. The sensor sensitivity ramp down with the increase in coverage density of reactive reagents, yielding two linear regions demarcated by 0.3 coverage, which are identified by the experimental results and simulations. The universal nature of template-assisted patterning allows adjustments in the composition, size, and shape of the constituent material, including nanofibers, nanoparticles, and molecules, and thus serves to improve the sensitivity of gas sensors for detecting various volatile organic compounds.

The opto-electro-mechanical system as a quantum interface between electronic information and optical information plays an important role in quantum information processing. Ground-state cooling of the macroscopic mechanical oscillator is a crucial requirement for this system in order to eliminate the effect of thermal fluctuations on transmission of information. Here, we propose a scheme of ground-state cooling for a mechanical oscillator which is coupled to an optical cavity through radiation pressure force and simultaneously coupled to a superconducting microwave cavity through an effective capacitance. Meanwhile, the periodical frequency modulations are applied to the optical mode, microwave cavity, and mechanical mode, respectively. The cooling efficiency is analyzed and cooling dynamics is simulated numerically by means of covariance matrix. The results show that the Stokes heating processes can be suppressed effectively by means of frequency modulations, and the mechanical oscillator can be cooled to near its ground-state with a higher efficiency than that of a standard optomechanical system due to the double cooling channel. Moreover, a complementary cooling effect is found between these two cooling channels, i.e., a high cooling efficiency can be achieved by cooperation between a good optical cavity and a bad microwave cavity, or vice versa. This cooperative cooling of the double channel breaks the limitation of resolved-sideband regime.

Wear is an inevitable phenomenon in the working process of clutch and brake system. With the increase of transmission speed and power density, the thermoelastic instability (TEI) of clutch and brake system is becoming more serious over time. It is difficult to obtain the practical solution for conventional materials of clutches and brakes and their actual geometry with finite thickness using the existing analytical method. To study the comprehensive effects of wear and friction pair thickness on TEI, Archard Wear Law is combined with the Fourier Reduction Method to develop a finite element model, the accuracy of which is validated using the existing analytical method. Within the usual ranges of thickness and wear coefficient of friction pair, the increase of friction material thickness or the decrease of steel material thickness will suppress the TEI. Nonetheless, if the wear-rate is increased significantly, the effect of friction material thickness will be reversed. The worst thickness, which must be avoided in the design, and the local optimum thickness exist for the steel material.

To detect biomarkers from human exhalation, air flow dynamics on the nanoparticle surface were explored by a surface-enhanced Raman scattering (SERS) sensor. A hollow Co-Ni layered double hydroxide (LDH) nanocage on Ag nanowires (Ag@LDH) was prepared. Ag nanowires provided amplified Raman signals for trace determination; hollow LDH nanocages served as the gaseous confinement cavity to improve capture and adsorption of gaseous analytes. The Raman intensity and logarithmic analyte concentration exhibit an approximately linear relationship; the detection limit of SERS sensors for aldehyde is 1.9×10-9 v/v (1.9 ppb). Various aldehydes in mixed mimetic gas are distinguished by Raman spectra statistical analysis assisted by multivariate methods, including principal component analysis and hierarchical cluster analysis. The information was recorded in a barcode, which can be used for the design and development of a desktop SERS sensor analysis system for large-scale lung cancer detection.

Vehicles are subject to a variety of road unevenness and random road excitations that potentially cause the vehicle to undergo a significant amount of energy dissipation, while compromising energy efficiency. This paper focuses on designing a novel piezoelectric energy harvester and aims to assess the energy harvesting potential, from the vehicle suspension, under random and pulse road excitations. To describe the energy harvesting process, a dual‐mass suspension system vibration model of a light electric logistics vehicle, equipped with a piezoelectric energy harvester, is developed. Various parameters, such as driving speed, ratio of the moment arms of the lever, and piezoelectric material cross‐sectional area, are included in the model, for basic harvesting energy. The root mean square (RMS) value of harvested power, in the case of random road, is up to 18.83 W, while the maximum respective value, in the case of pulse road, is 102.24 W and is obtained at 30 km/h. The harvested electricity is very valuable and useful, as it can be used to power automotive electrical equipment. The results of this paper provide an important reference frame for future research, related to energy harvesting from vehicle suspension.

Steel plate shear wall (SPSW) systems have been used increasingly in medium- and high-rise buildings in recent decades. Two major issues in the slender-web SPSW are the buckling of H-section steel column base and significant pinching in hysteretic curves. As a solution, SPSW using concrete-filled steel tubular (CFST) column and cross stiffeners was proposed in this paper. Cyclic tests of two specimens of 1/3 scaled steel beam-to-CFST column frame-thin SPSW with cross stiffeners or without stiffeners were conducted. Based on the verified finite element method, parametric investigations considering the effect of the flexural rigidity of CFST column, width-to-height aspect ratio, height-to-thickness ratio of infill steel plate and relative rigidity of cross stiffener were carried out. Findings show that SPSW using CFST column exhibited favorable ductility behavior with no sudden loss of lateral bearing capacity. Adding stiffeners to SPSWs relieves the pinching effect of hysteretic curves and reduces the maximum lateral displacement substantially. With stiffeners, the average yield load and the peak load of SPSWs were approximately 15% and 9% higher than that of the unstiffened specimens. Moreover, a flexural rigidity of CFST column of at least 2.5 and a stiffener rigidity of 30–50 were recommended to provide an economical and approving lateral bearing capacity.

Optimising the supported modes of atom or ion dispersal onto substrates, to synchronously integrate high reactivity and robust stability in catalytic conversion, is an important yet challenging area of research. Here, theoretical calculations first show that three-coordinated copper (Cu) sites have higher activity than four-, two- and one-coordinated sites. A site-selective etching method is then introduced to prepare a stacked-nanosheet metal–organic framework (MOF, CASFZU-1)-based catalyst with precisely controlled coordination number sites on its surface. The turnover frequency value of CASFZU-1 with three-coordinated Cu sites, for cycloaddition reaction of CO2 with epoxides, greatly exceed those of other catalysts reported to date. Five successive catalytic cycles reveal the superior stability of CASFZU-1 in the stacked-nanosheet structure. This study could form a basis for the rational design and construction of highly efficient and robust catalysts in the field of single-atom or ion catalysis., Engineering the coordination mode of atom or ion onto the substrate remains challenging. Here, guided by theoretical calculation, the authors prepare stacked-nanosheet MOF based catalyst with precisely controlled coordination sites on the surface and enhanced catalytic reactivity and structural robustness.

Traditional column base connections typically designed as fully restrained moment connections are questionable to be applied in self-centering seismic resisting structural systems. In this study, three types of self-centering concrete-filled square steel tubular (CFST) column base connections, i.e., Type I and Type II fabricated with post-tensioned (PT) strands and sandwiched energy dissipaters constructed in opposite and the same directions respectively and Type III fabricated PT strands and sandwiched energy dissipaters in orthogonal direction are proposed. Results shed light on the influence of these bases on seismic performance, beginning with a cyclic experimental investigation on three 3/4 scaled of Type I test specimens. Findings demonstrate that all test specimens exhibited typical flag-shaped hysteretic loops with the expected deformation mode, stable energy dissipated and good self-centering ability with 0.14% of the maximum recorded residual drift at 2% drift. Under 4% drift, the buckling restrained steel (BRS) plates yielded while the column and strands remained elastic, creating no damage to the main structural elements. Moreover, an analytical model of three types of self-centering CFST column base connections was developed, which are able to predict the column base connections moments reasonably.

Ru nanoparticles doped in carbon foam were encapsulated in nitrogen-doped graphite carbon materials (Ru-NGC). The resultant Ru-NGC possesses superior hydrogen evolution activity with a small onset potential of 9.5 mV and excellent durability due to the optimized Ru electronic state in nitrogen-doped graphite.

This paper discusses the impact of Fischer-Tropsch (F-T) diesel and methanol blended fuel, tentative engine was operated with fueled having F-T diesel and methanol blended fuel to compare the combustion and vibration characteristics. For this, 4100QBZL turbocharged diesel having parameters of F-T diesel fuel, FM5, FM10, FM15 methanol volume content was 5%, 10%, and 15%, respectively, have been selected for the experiment. Experimental studies have shown that when fueling with F-T diesel fuel, the ignition delay is shorter, the premixed combustion rate peak is lower, and vibration acceleration increases slightly than diesel fuel. Compared to the pure F-T diesel, the blended fuel has longer ignition delay period, higher the rate of pressure rise, combustion start point delayed, burning capacity increase, such as thermal efficiency is improved and vibration acceleration increased significantly.

Background To investigate the optimal placement and size of adhesive thyroid cartilage electrodes (ATCEs) placed on the thyroid cartilage in porcine models for evaluating recurrent laryngeal nerve function compared with the other 3 recording electrode types. Methods Four Meishan piglets were used for this study. The electromyogram (EMG) signal stability was detected by intraoperative nerve monitoring (IONM). Best location and size of ATCEs were detected, and the EMG signals from each were compared. Latency data were tested by stimulating the different nerve points, and 6 manipulations of the trachea and endotracheal tube (ET) were applied to test the stability of EMG signals. ET electrodes, needle electrodes, and transcutaneous recording electrodes were simultaneously tested with comparison to ATCEs. Results The optimal placement locations and sizes of ATCEs were determined. The amplitudes and latencies recorded from the ATCEs were consistent with those of the ET electrodes. More anti-interference was observed with the ATCEs than with the ET electrodes in surgical manipulations. ATCEs could be used during intermittent and continuous monitoring in similar fashion to ET electrodes and needle electrodes. Conclusions ATCEs had consistent monitoring function with ET electrodes and needle electrodes. Feasibility, EMG stability, and optimal location and size of ATCEs for IONM were resolved. The EMG profiles from the ATCEs were more stable during surgical manipulations.

To monitor the gradual wear process of gears, the wear behavior at different lifetime phases has to be fully understood in theory. The traditional Archard’s wear model was mainly developed for dry contact. However, for the most gear transmission systems, the gears normally work under the mixed EHL regime, and the two contact gear surfaces are separated by a thin film to avoid the asperity contact. Therefore, the traditional Archard’s wear model is inappropriate to estimate the wear depth of the lubricated contact. Moreover, the numerical simulation of helical gear wear was rarely studied because of the time-varying characteristics. To simulate the wear depth of helical gear in more realistic, the helical gear was regarded as a combination of a number of spur gears with a continuous different angle. By estimating the wear depth of each slice of the spur gear, the wear depth of the helical gear can be achieved. Besides, this paper employs a modified Archard’s wear model which is suitable for the contact in the mixed EHL regime. In this model, the asperity contact pressure was derived from the Hertzian contact theory, and both the friction effect, contact temperature, surface roughness, load sharing, and lubricant characteristics were considered for more realistic operating conditions. The sliding distance at each meshing position was determined by the single point observation method. The numerical results illustrate that the wear depth simulated from the mixed EHL regime is much lower than that under the dry contact condition, which is in good accordance with the lubrication theory. In addition, the wear depth increases with the operating load but decreases with the operating speed.

Continuous intraoperative neural monitoring (C-IONM) during thyroid surgery is a useful tool for preventing recurrent laryngeal nerve (RLN) injury. The present study aims to analyze the tensile strength tolerance of C-IONM electrodes on the vagal nerve (VN). A C-IONM wire was enclosed in a hand-held tensile testing system. The probe displacement on the VN was continuously monitored by positioning a second probe far-up/proximally in a piglet model, and an automatic periodic stimulation (APS) accessory was used. The 3-mm and 2-mm APS accessory has a mean tensile strength of 20.6 ± 10 N (range, 14.6–24.4 N) and 11.25 ± 8 N (range, 8.4–15.6 N), respectively (P = 0.002). There was no difference between bilateral VNs. The mean amplitude before and during electrode displacement was 1.835 ± 102 μV and 1.795 ± 169 μV, respectively (P = 0.45). The mean percentage of amplitude decrease on the electromyography (EMG) was 6.9 ± 2.5%, and the mean percentage of latency increase was 1.9 ± 1.5%. No significant amplitude reduction or loss of signal (LOS) was observed after > 50 probe dislocations. C-IONM probe dislocation does not cause any LOS or significant EMG alterations on the VN.

The properties and performance of solid nanomaterials in heterogeneous chemical reactions are significantly influenced by the interface between the nanomaterial and environment. Oriented tailoring of interfacial dynamics, that is, modifying the shared boundary for mass and energy exchange has become a common goal for scientists. Although researchers have designed and constructed an abundance of nanomaterials with excellent performances for the tailoring of reaction dynamics, a complete understanding of the mechanism of nanomaterial-environment interfacial interaction still remains elusive. To predictively understand the nanomaterial-environment relationship over a wide range of time scale, a deep and dynamic insight is required urgently. In this Account, our recent works including advances in the design and construction of nanoassembled interfaces and understanding the dynamic interaction mechanisms between different combinations of nanoparticle (NP) assembly environment interfaces for tailoring the reaction dynamics.NP assemblies with well-defined structures and compositions are inherently suitable for replacing bulk-type nanomaterials for the research on interfaces. We primarily introduced two most relevant nanoassembled surfaces that were fabricated in our laboratory, namely, ordered self-assembly interface and animate nanoassembled interface. The disordered nanoparticles can be arranged into an ordered superlattice based on the self-assembly method and patterned-assembly method. In addition, we used NPs with flexible properties to construct three-dimensional (3D) animate assemblies. On the basis of a thorough understanding of the structure-property correlation, a series of nanoassembled interfaces with various structures have been developed for practice. In comparison with traditional nanomaterial-environment interfaces, the nanoassembled interfaces can change the mode of contact between the nanomaterial and environment, thereby maximizing the number of active sites and driving interferent/product off the nanoassembled interface. The geometry, porosity, and deformable/motional properties in the nanoassembled interface can be applied to enhance the mass transfer dynamics in the chemical reaction. Moreover, the nanoassembled interface can be used to strengthen the affinity between the NP assemblies and targets, thereby enhancing the adsorption efficiency. As shown in these examples, the nanoassembled interface can effectively change the speed, intensity, and mode of interactions between the NP assemblies and environment in spatiotemporal scales.The overall performance of the interfacial dynamics can be improved by the nanoassembled interface, thereby facilitating practical application in flowing systems. We have extended the applications of nanoassembled interfaces from simple adsorption to complex reactions in flowing systems, including in vivo magnetic resonance imaging, electrocatalytic gas evolution reaction, bacterial capture, sensing of exhaled volatile organic compounds, and heterogeneous catalysis. Our current endeavors to explore the applicability of animate nanoassembled interfaces for dynamic tailoring have widened the scope of research, and attempts to construct intelligent interfaces for applications are underway.

Previous studies overlooked dynamic properties of NP assemblies; therefore, we highlight recent advances in animate properties., Nanoparticle (NP) assemblies are among the foremost achievements of nanoscience and nanotechnology because their interparticle interactions overcome the weaknesses displayed by individual NPs. However, previous studies have considered NP assemblies as inanimate, which had led to their dynamic properties being overlooked. Animate properties, i.e., those mimicking biological properties, endow NP ensembles with unique and unexpected functionalities for practical applications. In this critical review, we highlight recent advances in our understanding of the properties of NP assemblies, particularly their animate properties. Key examples are used to illustrate critical concepts, and special emphasis is placed on animate property-dependent applications. Last, we discuss the barriers to further advances in this field.

As the contact point and contact path seriously affect the spiral bevel gear mesh characterize, the tooth modification method was applied to manufacture, and tooth contact markers can verify the contact area. However, when the contact area wear happen, the actual contact area may be changed which is not the expectation. And hence, the spiral bevel gear transmission is more sensitive to wear compare with parallel shaft gear transmission. The vibration response would reflect the wear severity. Nonetheless, the relative motion of spiral bevel gear contacting areas, which cause tooth surfaces wear, is rather complex on account of time-vary proportion of rolling and sliding. Moreover, the wear is not uniform, if there were some defects on the surface, the wear would intensify the defect. Modulation signal bispectrum (MSB) has been proven to be an effective monitoring approach which is sensitive to gear tooth defect. Spiral bevel gear tooth modification, which can change the contact area, is very important to the dynamic performance. To assess the improvement of the modification to tooth wear, a run-to-failure experiment of modification spiral bevel gear was carried out under accelerated wear conditions, and MSB method is applied to analysis the gearbox housing vibration signal to indicate the wear progress. The experimental results demonstrated the accuracy and reliability of the MSB-SE monitoring approach proposed.

Gears are important components of the transmission system. Tooth wear and bearing clearance are significant factors affecting the dynamics of the gear system. In order to reveal the effects of gradual wears and bearing clearance on the gear system dynamics, a six-degrees-of-freedom bending-torsion coupled model of gear-rotor-bearing which considers surface wear, bearing clearance and backlash is established. The Rung-Kutta method is used to solve the nonlinear dynamic system, and the dynamic responses of the system are obtained. The results show that the time-varying mesh stiffness decreases with the tooth surface from the unworn phase to severe wear phase. At the same time, the change of the mesh stiffness in the double-tooth mesh area and single-tooth area are different. Moreover, the amplitude of the X-displacement, Y-displacement and relative gear mesh displacement will be enlarged slightly with the increase of wear depth or bearing clearance. By analyzing variation tendency in the frequency domain, the different order harmonics show the different change characteristic with the variation of the wear phases or bearing clearances. This study provides a theoretical basis for improving the transmission performance and the selection of the bearing clearances in the gear system.

To enhance the stability in humidity is very crucial to hybrid organic-inorganic lead halide perovskites in a broad range of applications. This report describes a coating stratergy of perovskite nanocrystals via polymethylmethacrylate-introduced ligand-assisted reprecipitation, using the interactions between the Pb cations on the surface of perovskite nanocrystals and the functional ester carbonyl groups in polymethylmethacrylate framework. The hydrophobic framework shields the open metal sites of hybrid organic-inorganic lead halide perovskites from being attacked by water, effectively retarding the diffusion of water into the perovskite nanocrystals. The as-prepared films demonstrate high resistance to heat and moisture. Additionally, the introduction of polymethylmethacrylate into ligand-assisted reprecipitation can effectively control the bulk precipitation and promote the stability of the perovskite solution.

Bacterial infectious diseases, such as sepsis, can lead to impaired function in the lungs, kidneys, and other vital organs. Although established technologies have been designed for the extracorporeal removal of bacteria, a high flow velocity of the true bloodstream might result in low capture efficiency and prevent the realization of their full clinical potential. Here, we develop a dialyzer made by three-dimensional carbon foam pre-grafted with nanowires to isolate bacteria from unprocessed blood. The tip region of polycrystalline nanowires is bent readily to form three-dimensional nanoclaws when dragged by the molecular force of ligand-receptor, because of a decreasing Young’s moduli from the bottom to the tip. The bacterial capture efficiency was improved from ~10% on carbon foam and ~40% on unbendable single-crystalline nanowires/carbon foam to 97% on bendable polycrystalline nanowires/carbon foam in a fluid bloodstream of 10 cm s−1 velocity., Bacteria and other pathogens entering the blood stream can have serious consequences, which can even lead to death. Here, the authors developed a sieve containing nano-sized claws that capture and hold these intruders, thus aiding their removal from patient’s blood

Surface-enhanced spectroscopy (SES), including surface-enhanced Raman spectroscopy (SERS), surface-enhanced infrared absorption (SEIRA), surface-enhanced fluorescence (SEF), surface-enhanced hyper-Raman spectroscopy (SEHRS), surface-enhanced second harmonic generation (SESHG), and surface-enhanced electrochemiluminescence (SEECL), is an emerging subject that has received significant attention from the research community over the past 40 years. The confined and strong enhanced electromagnetic fields generated from the surface of noble metal nanostructures are considered as the main cause of SES. More importantly, it has been proven that SES is strongly related to the orientation and inter-nanoparticle coupling of different nanostructures. This review article mainly focuses on the application of ordered nanoparticle self-assemblies in SES. Different strategies for the fabrication of ordered nanoparticle self-assemblies, the mechanisms of SES, and the application of SES have been reviewed in detail.

This paper involves an exhaust gas waste heat recovery system for vehicles, which uses thermoelectric modules and a heat exchanger to produce electric power. Based on summarizing the latest research of vehicle exhaust thermo-electric generator (TEG), it presents two new fin structures for the cylindrical heat exchanger in a TEG system. It mainly studies the thermal performance of two kinds of three-dimensional cylindrical heat exchanger models including spiral-fin heat exchanger with variable pitch in a computational fluid dynamics simulation environment. In terms of interface temperature and thermal uniformity and based on an evaluation method of the temperature uniformity for the heat exchangers, the thermal characteristics of heat exchangers with different pitch angle of the twisted fins, pitch of spiral fin, fin thickness and fin height are discussed. Two new fin structures are feasible to enhance the heat transfer performance of heat exchanger.

For the first of time, we demonstrate that methylammonium cadmium halides show photoelectrochemical (PEC) response with excellent humidity and chemical resistance because the oxidation state of almost all cadmium compounds is +2. The photocurrent densities of two-dimensional (2D) layered (MA)2CdCl4 perovskites are about 0.30 mA cm−2 under 100 mW cm−2 irradiation. The interaction between these methylammonium cadmium halides and water vapor is studied by probing film morphology and characterizing single crystal structure. It is shown that H2O is able to complex with the perovskite, forming a hydrate product with the molecular formula of MACd3Cl7·3H2O upon humidity exposure. This causes a decrease in absorption and a recognizable change in the crystal structure of the material. When compared to methyl-ammonium lead iodide (MAPbI3), the PEC stability of 2D layered (MA)2CdCl4 perovskites with BQ/BQ˙− redox couples (where BQ is benzoquinone) in CH2Cl2 is enhanced from 50 hours to 600 hours, exhibiting an increase of 12 times.

Autoclaved aerated concrete waste (AACW) is an inorganic porous construction and demolition waste, which is possible to be environmentally used as an internal curing agent, due to its water absorption and release characteristics. In present work, fine aggregate (sand) was replaced by AACW aggregate with the same volume for internal curing purpose. The potential curing effect of AACW was also compared with a classical internal curing agent, i.e. expanded perlite (EPA), under the same particle size condition. Results indicate that the compressive strength of AACW groups after 28-day sealing curing is basically the same as that of the control group. Compared with EPA, internal curing with AACW can better improve the internal relative humidity, reduce the autogenous shrinkage, and delay the cracking time of cement mortar. At the same time, AACW effectively refines the pore structure and improves the micro-hardness of the interfacial transition zone (ITZ) through internal curing, and enhances the resistance to chloride penetration.

Herein, we focus on the design and geometry diversities of two dimensional LDHs nanosheet building blocks from lamellar to hierarchical structures to understand mass transfer mechanisms and highlight the importance of geometry-induced effects to overcome the diffusion constraints in solid–liquid interfaces.

In this paper, a new type of piezoelectric harvester for vehicle suspension systems is designed and presented that addresses the current problems of low energy density, vibration energy dissipation, and reduced energy harvesting efficiency in current technologies. A new dual-mass, two degrees of freedom (2-DOF), suspension dynamic model for the harvester was developed for the inertial mass and the force of the energy conversion component by combining with the piezoelectric power generation model, the rotor dynamics model, and the traditional 2-DOF suspension model. The influence of factors such as vehicle speed, the parameters of the harvester, and road classification on the root mean square (RMS) of the generated electric power is discussed. The results show that the RMS increases with the increase of the speed of the vehicle, the thickness and length of piezoelectric patches and magnetic slabs, and the residual flux density of magnets and road roughness coefficient and with the decrease of the width of piezoelectric patches and magnetic slabs and the space between the stator ring and the rotator ring. In the present research, a power of up to 332.4 W was harvested. The proposed model provides a powerful reference for future studies of energy harvesting from vehicle suspension systems.

This paper focuses on two novel enhancement schemes for thin-walled square concrete filled steel tubular (CFST) columns, i.e., diagonal rib stiffener and circular liner stiffener, with the advantages of sufficient confinement, easy fabrication, and flat outer surface. Seven thin-walled square CFST columns were tested under pseudo-static loading, considering the parameters of stiffener type, the width-to-thickness ratio of steel tube, and axial load ratio. The test results indicated that all the stiffened specimens showed excellent seismic performance with higher lateral resistance, better ductility, and greater energy dissipation than the unstiffened counterpart. The specimens with diagonal rib stiffeners effectively restricted the local buckling of the square steel tube but suffered a weld fracture between the tube plate and the diagonal rib at a large drift ratio. The circular liner stiffener could provide sufficient confinement to the core concrete. Even in the case of a high axial load ratio of 0.6, the circular liner stiffened specimen still showed a ductile behavior with the ultimate drift ratio (DR0.85) of 1/35 and the ductility coefficient (μ) of 4.3. The hysteretic behavior of the thin-walled square CFST columns with diagonal rib/circular liner stiffeners was predicted by both the FE model and the simplified theoretical model, in which the post-buckling strength of the thin-walled square steel tube and the confinement effect of the stiffeners are considered.

The modified coffee-ring effect is used to self-assemble highly uniform, long-range-ordered Ag nanowire arrays. As the oriented Ag nanowire arrays provide excellent membranes for surface-enhanced Raman scattering, the molecular mechanism of cell adhesion and growth is systematically studied and well understood. This work has important significance for life science research.

A hierarchical, intrafibrillarly mineralized collagen (HIMC) is achieved through a selective mineralization progress in the collagenous gap regions mediated by poly(acrylic acid) with appropriate molecular weight. The associated topographical features directly correlate with nanomechanical heterogeneities of the HIMC to accommodate a broad range of external loads. Moreover, this hierarchically staggered nanostructure provides an optimized microenvironment to improve bone regeneration by instructing host cells.

In this paper, PbTe nanocubes are assembled on Bi0.5Sb1.5Te3 substrates with both ordered and disordered structures through a straightforward method to form a P-N section. The work function of such semiconductor system is then measured by the ultraviolet photoelectron spectroscopy. This results show that the work function of orderly arrayed PbTe deposition is much lower than the disordered assemblies. Such change of the work function provides the possibility to tune it in a P-N section system. The change of the work function is attributed to the less surface roughness and easier electron escaping in the ordered structures.

Bone, as a mineralized composite of inorganic (mostly carbonated hydroxyapatite) and organic (mainly type I collagen) phases, possesses a unique combination of remarkable strength and toughness. Its excellent mechanical properties are related to its hierarchical structures and precise organization of the inorganic and organic phases at the nanoscale: Nanometer-sized hydroxyapatite crystals periodically deposit within the gap zones of collagen fibrils during bone biomineralization process. This hierarchical arrangement produces nanomechanical heterogeneities, which enable a mechanism for high energy dissipation and resistance to fracture. The excellent mechanical properties integrated with the hierarchical nanostructure of bone have inspired chemists and material scientists to develop biomimetic strategies for artificial bone grafts in tissue engineering (TE). This critical review provides a broad overview of the current mechanisms involved in bone biomineralization, and the relationship between bone hierarchical structures and the deformation mechanism. Our goal in this review is to inspire the application of these principles toward bone TE.

The morphologies of nanomaterials have great influence on their properties. In this work, we used the solvothermal method to prepare tungsten oxides with two different morphologies: WO2.72 nanowires and urchin-like WO2.72 nanostructures. The photocatalytic activities of these two bare WO2.72 nanostuctures were evaluated by their efficiency in the degradation of pollutants, during which the influence of the morphology was taken into account. In the experiments, material structures and oxygen vacancies were altered with the change of the morphology. One-dimensional WO2.72 nanowires with fewer oxygen vacancies showed higher photocatalytic activity than three-dimensional urchin-like WO2.72 nanostructures with more oxygen vacancies. Thus, we ascertained the prominent role of the structure, rather than the number of oxygen vacancies, in enhancing photocatalytic activity. Surface photocurrent (SPC) measurements further confirmed that WO2.72 nanowires were more conducive to photo electron transfer than urchin-like WO2.72 nanostructures, which corresponded with the results of photocatalysis. Compared with commercial nanostructured tungsten oxide, both the WO2.72 nanowires and urchin-like WO2.72 nanostructures exhibited enhanced photocatalytic activities for the degradation of pollutants under UV light irradiation.

Metal-organic frameworks (MOFs), built from organic linkers and metal ions/clusters, have emerged as highly promising materials for wide applications. Combining highly porous crystalline MOFs with the surface-enhanced Raman scattering (SERS) technique can achieve unprecedented advantages of high selectivity, high sensitivity, and expedience in analysis and detection. In this critical review, the aim is to present a comprehensive review of recent advances in understanding of the roles of MOFs in MOF-SERS systems, particularly their structure-to-property correlation. Key examples are selected from representative literature to illustrate critical concepts and the MOF-based property-dependent applications are particularly emphasized. Finally, the barriers, future trends, and prospects for further advances in MOF-SERS platforms are also discussed.

Taking inspiration from natural materials, composite materials can be reinforced by creating matrix architectures that can better accommodate and control internal stresses. Despite the recent success in the synthesis of artificial assemblies for local reinforcement through the introduction of oriented fibers and plates into host multilayered composites, there is a lack of fundamental understanding of the factors that determine mechanical properties. Moreover, designing building blocks and interfaces that facilitate higher resistance and energy dissipation is highly challenging. When the intrinsic material is fixed, the mechanical and tribological properties can be further adjusted. In this study, europium oxide nanosheets are arranged in interlocked-junction superstructures that resist sliding at junction points, thereby enhancing the mechanical properties of the nanosheet assemblies compared to those of the conventional face-to-face superstructures formed by parallel nanosheets. Furthermore, the crystalline origin of building blocks is revealed by demonstrating that faulty crystal nanosheets adopting an amorphous structure are different from single-crystal nanosheets, with the former exhibiting superior mechanical reinforcement and improved abrasive resistance.

A post-tensioned (PT) beam-to-column connection using wedge-shaped devices (WSDs) and concrete-filled square steel tubular (CFST) column is proposed in this study. The WSD is designed to eliminate the gap between the nut on the energy-dissipating (ED) bar acting as “fuse” and the end plate of the beam when the ED bars yield during an earthquake. Cyclic tests were carried out on four 2/3 scaled specimens to investigate the mechanical behaviour and seismic behaviour of the connection considering the effect of the initial PT force, the area of ED bars and the use of WSDs. Findings demonstrate that the connections using WSDs exhibited desired flag-shaped hystereses before the bottom of the U-shaped surface on the wedge contacted with the ED bar. All the specimens were able to recentre while the structural elements behaved elastically after each cyclic loading and the “fuses” were replaced after each test. Besides, the self-centring behaviour was insensitive to the initial PT force and the size of ED bars. Smaller amount of energy dissipation and initial rotational stiffness were observed after the bottom of the U-shaped surface contacted with the ED bar. Moreover, simplified equations were developed to predict the mechanical behaviour of the PT connection and showed good correlation compared with the experimental results, which can be used in a non-linear structural analysis program.

The engineering of metal–organic frameworks (MOFs) into membranes and films is being investigated, to transform laboratory‐synthesized MOFs into industrially viable products for a range of attractive applications. However, rational design and construction of highly permeable MOF thin films, without trade‐offs in terms of structural mechanical stability, remains a significant challenge. Herein, a simple, general strategy is reported to prepare thin MOF nanosheet (NS)‐assembled frame film via heteroepitaxial growth from metal hydroxide film. As the thin MOF NS‐assembled film significantly enhances the permeability of mass though the film, the resultant gold nanoparticle (Au NP)@MOF film exhibits much higher catalytic efficiency than the Au NP@MOF bulk film. Meanwhile, the unique framework of the MOF NS‐assembled film resists torsion and collapse, so the composite catalyst exhibits long‐term stability., A thin metal–organic framework nanosheet‐assembled frame (MOF NAF) film is prepared via a facile heteroepitaxial growth strategy. The thin MOF NAF film significantly enhances the permeability of the film and the unique framework structure endows the MOF NAF film with high mechanical stability.

A simple method was adopted in which ultrathin cerium oxide nanoplates (

Experimental research was conducted on a turbo-charged, inter-cooling and common-rail diesel engine with Fischer&ndash, Tropsch fuel synthesized from Coal-to-liquid (CTL), in order to investigate the influence of different injection parameters on the combustion, emissions and efficiency characteristics of the engine. The results showed that the ignition point was advanced, the in-cylinder pressure and heat release rate increased as the injection timing advanced and the injection pressure increased. By comparing the peak in-cylinder pressure of 100 cycles for one sample, it was found that the coefficient variation (COV) remained under 2% throughout the tests and the combustion process remained stable. NOx emissions decreased with delayed injection timing and lower injection pressure. In contrast to NOXNOx emissions, soot emissions were almost zero when the injection pressure was up to 143.5 MPa. The indicated thermal efficiency (ITE) showed no obvious change with different injection parameters, and remained under 40% in all the tests.

This study presents an experimental approach based on partial tooth meshing contact fatigue with constant amplitude and different lengths of load cycles. To achieve this, 20CrH helical gears were considered, limiting the region of interest to one-third of the tooth to accelerate crack initiation and propagation. Different factors, such as number of fatigue cycles, tooth flank morphology, residual stress, hardness, and microstructure evolution under fatigue, were considered. The ultimate goal was to relate these variations with the observed failure modes. The results showed that with increasing cycle number, the residual stress at the same position in the meshing zone of the tooth flank increased first and then decreased. The residual stress values at the lower position of the pitch circle were larger than that of the addendum and dedendum. After cyclic loading, the content of the twin martensite within the microstructure below the pitch circle decreased and the corresponding hardness value of the tooth flank was reduced. After long-term cyclic loading, the precipitated phases aggregated and grew and the discontinuous distribution hindered the grain boundary slip. The dislocation density increased, and the pile-up of dislocation resulted in stress concentration at the grain boundary and the phase boundary, which induced the initiation of fatigue crack of the tooth flank.

Fischer-Tropsch diesel fuel synthesized from coal (CFT) is an alternative fuel that gives excellent emission performance in compression ignition (CI) engines. In order to study the vibration characteristics, which are important for determining the applicability of the fuel, CFT-diesel blends were tested on a CI engine to acquire vibration signals from the engine head and block. Based on the FFT and continuous wavelet transformation (CWT) analysis, the influence of CFT on the vibration was studied. The results showed that the root mean square (RMS) values of the vibration signal decrease as the proportion of CFT in the blends increases. The CWT results indicated that the vibration energy areas motivated by the pressure shock of transient combustion were weak with increasing CFT proportion for the different frequency bands. The blend of 90% pure petro-diesel and 10% CFT registered the largest RMS value for piston side thrust response, and the RMS of high-frequency pressure oscillation response is greater than that of the main response of combustion, for FT30. Therefore, CFT has the potential to reduce the combustion vibration of the engine at all frequency bands, and there is a possibility that the proportion of blended fuel can be modified to satisfy the vibration characteristics requirements in different frequency bands.

In the synthesis of lead telluride nanocrystals (PbTe NCs), oxidized PbTe is commonly regarded as a waste material as this will reduce the performance of pure PbTe NCs. The waste is normally thrown away, leading to potential environment risks and is less economical in terms of atom usage. Conventional anti-oxidation methods such as inert gas flow or sealed systems cannot deal with leaking or accidental contamination. To solve this problem, by simulating accidental oxidation, we utilized a cheap and easily-performed strategy to reduce the oxidation to a very low level. Further analysis indicates that this anti-oxidation effect should be due to interactions between the double bonds from the coating ligands and the extended π bonds from the benzene rings. This strategy increases the synthesis efficiency of the reactants and reduces the environmental pollution risk.

Colloidal nanoparticle assemblies are widely designed and fabricated via various building blocks to enhance their intrinsic properties and potential applications. Self-assembled hollow superstructures have been a focal point in nanotechnology for several decades and are likely to remain so for the foreseeable future. The novel properties of self-assembled hollow superstructures stem from their effective spatial utilization. As such, a comprehensive appreciation of the interactive forces at play among individual building blocks is a prerequisite for designing and managing the self-assembly process, toward the fabrication of optimal hollow nanoproducts. Herein, the emerging approaches to the fabrication of self-assembled hollow superstructures, including hard-templated, soft-templated, self-templated, and template-free methods, are classified and discussed. The corresponding reinforcement mechanisms, such as strong ligand interaction strategies and extra-capping strategies, are discussed in detail. Finally, possible future directions for the construction of multifunctional hollow superstructures with highly efficient catalytic reaction systems and an integration platform for bioapplications are discussed.

Studies on the self-assembly of nanoparticles have been a hot topic in nanotechnology for decades and still remain relevant for the present and future due to their tunable collective properties as well as their remarkable applications to a wide range of fields. The novel properties of nanoparticle assemblies arise from their internal interactions and assemblies with the desired architecture key to constructing novel nanodevices. Therefore, a comprehensive understanding of the interparticle forces of nanoparticle self-assemblies is a pre-requisite to the design and control of the assembly processes, so as to fabricate the ideal nanomaterial and nanoproducts. Here, different categories of interparticle forces are classified and discussed according to their origins, behaviors and functions during the assembly processes, and the induced collective properties of the corresponding nanoparticle assemblies. Common interparticle forces, such as van der Waals forces, electrostatic interactions, electromagnetic dipole-dipole interactions, hydrogen bonds, solvophonic interactions, and depletion interactions are discussed in detail. In addition, new categories of assembly principles are summarized and introduced. These are termed template-mediated interactions and shape-complementary interactions. A deep understanding of the interactions inside self-assembled nanoparticles, and a broader perspective for the future synthesis and fabrication of these promising nanomaterials is provided.

Hardness test and microstructure observation revealed that both Hall–Petch and inverse Hall–Petch effects accompany the studied long-term use of backup roll material. The increase of hardness with the decrease of grain size induced by contact fatigue damage at the early stages of use of backup roll material is consistent with the Hall–Petch effect. However, the lower resistance capability to endure longer use and prevent initiation of cracks following the nanocrystalline formation after long-term use corresponds to the inverse Hall–Petch effect.