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Various thermal protective ablative materials (TPAM) have been extensively studied. However, there are few reports on the thermal stability, the ablation properties and ceramisation of vitreous silica fabric reinforced boron phenolic resin composites with an incorporation of MoSi2 (VMBPR) and their bending strength after ablation. At this work, the above performances of the composites were characterised and analysed. Results reveal that the addition of MoSi2 decreases the graphitisation temperature of glass carbon of BPR pyrolysis, promoting the formation of a more ordered structure of the glassy carbon during pyrolysis. Furthermore, compared with the composites without MoSi2 (VBPR), the linear and the mass ablation rate of VMBPR composites decrease by about 94.46% and 39.09%, and its room temperature bending strength after static ablation at 1400��C for 20 min is more than twice that of the fused fibre aggregation formed by VBPR composites. This is attributed to the ceramisation reaction of VMBPR composites at high temperature.

openaire: EC/H2020/796280/EU//CADOACCFAP The unique antibacterial characteristics of Ag nanomaterials offer a wide potential range of applications, but achieving rapid and durable antibacterial efficacy is challenging. This is because the speed and durability of the antibacterial function make conflicting demands on the structural design: the former requires the direct exposure of Ag to the surrounding environment, whereas the durability requires Ag to be protected from the environment. To overcome this incompatibility, we synthesize sandwich-structured polydopamine shells decorated both internally and externally with Ag nanoparticles, which exhibit prompt and lasting bioactivity in applications. These shells are biocompatible and can be used in vivo to counter bacterial infection caused by methicillin-resistant Staphylococcus aureus superbugs and to inhibit biofilm formation. This work represents a new paradigm for the design of composite materials with enhanced antibacterial properties.

In this paper, Ni/Zr–Yb–O catalysts with different sodium contents are prepared by a co-precipitation method, using aqueous Na2CO3 solution as a precipitant, and the effect of sodium on the catalyst structure and catalytic performance for syngas methanation is extensively investigated using five Ni/Zr–Yb–O catalysts, containing 0, 0.5, 1.5, 4.5 and 13.5 wt% Na+, those are denoted as Cat-1, Cat-2, Cat-3, Cat-4 and Cat-5 respectively. It is found that the interaction between Ni and support determines the catalytic performance of Ni/Zr–Yb–O and the residual sodium content negatively affects the interaction between Ni and support. Cat-1 exhibits an excellent catalytic performance. During a long run time of 380 h, no deactivation is observed and both CO conversion and CH4 selectivity maintain a level above 90%. However, Cat-3 and Cat-5 suffer rapid deactivation under the same reaction condition. The characterization results indicate the strong interaction between Ni and support enables Cat-1 to possess well dispersed Ni species, resistance to sintering and carbon deposition and thus the excellent catalytic performance. However, the presence of sodium ions over Ni/Zr–Yb–O degrades the interaction between Ni and support and the catalytic performance, especially for the stability. The relative weak interaction between Ni and support results in severe sintering of both ZrO2 and Ni under the reaction condition, carbon deposition and the poor catalytic performance.

Temperature significantly affects the physical and mechanical properties of granite. To have a comprehensive understanding of the thermal cycle effect on uniaxial compressive strength (UCS) and thermal damage rate, a series of thermal cycle experiments on granite specimens were carried out with five types of designed temperatures and five types of cycle number of thermal treatments. The experimental results indicate that UCS decreases and thermal damage rate increases as temperature and thermal cycle increase. UCS of specimens cooled in water condition after thermal damage treatment are lower than those cooled in air condition. In addition, two new phenomena related to thermal damage rate were observed. Firstly, previous studies have shown that a rapid value reduction of UCS of specimens with one thermal cycle treatment under air cooling condition can be observed at 400 ∘ C. While the temperature threshold for the specimens treated with more than one thermal cycle under water cooling condition increases to 550 ∘ C. Secondly, a thoroughly antipodal evolution law of the thermal damage rate for the specimens with multiple thermal cycle treatments is also observed as compared to those treated by only one thermal cycle. These differences might be induced by the different microcrack initial time and their development speed. The new findings are important to understand the failure mechanism and variation process of physical and mechanical properties of granite specimens subjected to thermal cycles.

The effect of TiB2 on the thermal stability of phenolic and the role of TiB2 on the high-temperature mechanical property of carbon–phenolic composites are investigated by introducing TiB2 particles into phenolic, and then TiB2 particles into carbon–phenolic composites. The results show that the thermal stability of phenolic is enhanced by TiB2 additions. And the enhancement in thermal stability of phenolic exhibits a positive effect on improving the high-temperature mechanical property of carbon–phenolic composites. The flexural strength at 1000 °C of carbon–phenolic composites is increased by 148.2% after introducing 20 wt% TiB2 particles into phenolic matrix. In the heating stage before high-temperature mechanical test, TiB2 particles react with oxygen or oxygen-containing molecules released by phenolic pyrolysis. Therefore, amorphous carbon coated with glassy B2O3 and ceramic particles forms a new compact matrix. The well-bonded interface provides TiB2 modified carbon–phenolic improved mechanical performance at high temperature.

In order to study the dynamic mechanical properties of styrene–acrylic latex with a core/shell structure, a variety of latexes were synthesized by semi-continuous seeded emulsion polymerization based on “particle design” with the same material. The latexes were characterized by rotary viscosimeter, dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), transmission electron microscope (TEM), dynamic mechanical analysis (DMA), and universal testing machine. The effects of difference at the glass transition temperature (Tg) of core and shell and the introduction of the “transition layer” on the damping and mechanical properties of latex film were studied. The results indicate that as the Tg of core and shell gets closer, the better the compatibility of core and shell, from phase separation to phase continuity. Furthermore, the introduction of the “transition layer” can effectively improve the tensile strength and tan δ (max) of the latex film. The tensile strength and maximum loss factor (f = 1 Hz) of latex with the “transition layer” increased by 36.73% and 29.11% respectively compared with the latex without the “transition layer”. This work provides a reference for the design of emulsion for damping coating.

In order to examine the dynamic mechanical properties, dynamic crack proposition process, and energy loss of fractured rock under dynamic loading, the specimens with different fracture dig angles were processed with Φ50 mm × 50 mm cylindrical sandstone, the impact loading test was conducted on 50 mm stem diameter split Hopkinson pressure bar (SHPB) experiment platform, and the whole process of crack propagation and dynamic failure was recorded using a high-speed camera. As a result, the dynamic mechanical properties such as stress wave fluctuation characteristics, peak strength and stress-strain relationship, crack initiation angle, stress and other dependencies with prefabricated fracture angle of the prefabricated fracture specimens under high strain rate were obtained, and the incident energy, absorbed energy, and energy absorption rates were compared to investigate the energy loss law in the dynamic loading; on the contrary, the effects of different loading rates on the dynamic mechanical properties of the sandstone specimens were identified, and finally a set of findings were presented.

Rock blasting fragmentation is a result of the combined action of a blast-induced stress wave and the blasting gas. Incorporating high-speed camera technology, an experimental system of high-speed digital image correlation is established and is extended to blasting research. Using two-dimensional model experiments, the action effects of a blast-induced stress wave and blasting gas on the formation of the crush and fracture zones are studied, and the blasting attenuation law in the elastic vibration zone is also analyzed. The results show that the blast-induced stress wave and the blasting gas are respectively the main driving forces for the crush zone and fracture zone formation. The effect of the blasting gas reduces the crush zone size and increases the crack propagation length as well as the medium's stress peak. In the elastic vibration zone, the radial and circumferential stress of the medium are both first compressive and then tensile. The radial and circumferential stress are respectively dominated by compressive and tensile stress , and the radial stress decays more rapidly. With increased distance from the borehole , the medium's stress state gradually turns from mainly circumferential tensile to mainly radial compressive. In addition, in decoupled charge blasting, the stress attenuation index shows a trend of initially increasing and then decreasing with the increase of the decoupling coefficient. Compared with the attenuation of the circumferential stress, the air filling in the decoupled charge blasting more significantly affects the radial stress attenuation.

ZrSi2 modified carbon–phenolic (C-Ph) composites are prepared using different weight loadings of zirconium silicide particle by compression moulding. The thermal stability and ablation resistance of composites are investigated by thermal gravimetric analysis (TGA) and oxyacetylene torch test. Moreover, the phase composition and microstructure of ablated surface are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and selected-area electron diffraction (SAED). The results show that introduced ZrSi2 particles result in an evident increase in the residual weights of C–Ph composites at high temperatures, and the enhancement in thermal stability under air atmosphere exhibits positive effects on improving the ablation resistance of C-Ph composites. The optimum ZrSi2 weight loading for the improvement of ablation resistance in C-Ph composites is 5wt%. The linear and mass ablation rates of composites after modifying with 5wt% ZrSi2 particles are reduced by 80.5% and 55.2%, respectively. This work provides an effective way to prominently improve the ablation performance of C–Ph composites, and it maybe become a backbone of thermal protection system in aerospace.

Designing metal-free g-C3N4 based photocatalytic system with efficient photocatalytic activity has received enormous attention in the field of environmental remediation because of its great potential for removing refractory contaminants. Herein, a novel metal organic framework (ZIF-8)-derived nitrogen doped carbon (ZIF-NC) modified g-C3N4 heterostructured composite was synthesized through a facile thermal treatment method. Benefiting from the hierarchical porosity, conductive network, and abundant exposed active sites for peroxymonosulfate (PMS) activation of MOF-derived nitrogen doped carbon, the introduction of MOF-derived nitrogen doped carbon into g-C3N4 not only facilitates the charge separation of g-C3N4 but also greatly accelerates PMS activation to yield high active SO4 − radical. The energy band diagrams derived from Mott-Schottky, valence band X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy studies indicate that the formed heterojunction between g-C3N4 and ZIF-NC is Schottky type. The ZIF-NC with lower Fermi level energy can serve as an excellent electron accepter to enable fast electron transfer from the conduction band of g-C3N4 to ZIF-NC and boost the charge separation of g-C3N4. Photoelectrochemical tests combined with multiple spectroscopic techniques further confirm the enhanced charge carrier separation performance of composite. As a result, the as-prepared hybrids displayed remarkably improved photocatalytic activities toward bisphenol A (BPA) degradation in the presence of PMS under visible light irradiation. The apparent rate constant, k, for BPA degradation of the ZIF-NC/g-C3N4 composites with PMS is approximately 8.6 times as high as that of bare g-C3N4. This work provides a promising approach on the rational design of high-performance, cost-effective photocatalysts for environmental remediation.

Hierarchical one-dimensional (1D) hollow nanostructures have attracted intense research attention due to their unique structures that may be capable of many promising applications. Here, we report a facile and effective strategy to prepare nickel silicate nanotubes (NiSNTs). Using this approach, mesoporous SiO2 nanorods served as sacrificial templates for a simple hydrothermal process to prepare NiSNTs via a self-template route. The obtained NiSNTs preserve the tubular hierarchical morphology and hollow interior structures, which confer the NiSNTs with high surface areas and large pore volumes. These features point to NiSNTs as superior candidates for efficiently adsorbing heavy metal ions and organic dyes in wastewater. Moreover, NiSNTs can also serve as both supports and nickel sources, forming nickel silicate/nickel nanocomposite tubes (NiSNTs/Ni) via in situ reduction of NiSNTs under hydrothermal conditions. The addition of nickel precursors and surface pre-activation are therefore unnecessary. The NiSNTs/Ni exhibit efficient and recyclable catalytic properties when used for the reduction of 4-nitrophenol (4-NP). With a rational adaption, we believe this synthetic strategy can be extended to fabricate multifunctional one-dimensional hollow nanostructures with diverse compositions and morphologies, which may be useful for environmental protection, catalysis, energy and many other important domains.

Engineering hollow particles with high complexity in their morphology or composition is highly desirable for both fundamental studies and practical applications. Here, we combine mussel-inspired polydopamine (PDA) chemistry with template-assisted and hydrothermal approaches to explore a general approach for engineering hollow PDA colloidal composite particles with tunable complexities in terms of particle geometry, shell architecture and chemical composition. PDA coating and hydrothermal treatment are carried out sequentially in the same environment, which not only simplifies the experimental procedure but also avoids the use of hazardous core-removers. This approach is generally applicable to a wide variety of colloidal templates irrespective of their shape, material and structure, allowing the void structure and geometry (spherical void, yolk-shell, multi-shells and non-spherical cavity) to be controlled. The surface of the PDA shell provides a versatile platform for a number of secondary reactions (e.g., electroless metallization, superhydrophobic modification, Michael addition and nanoparticle decoration). Consequently, tuning the exterior or interior of the hollow PDA shell with various functional materials offers a range of potential uses in superhydrophobic surfaces, catalysis, photocatalysis and surface-enhanced Raman spectrum sensing.

Surface-enhanced Raman scattering (SERS) sensor allows for fingerprinting and label-free molecular detection with a high sensitivity, but the simple fabrication of SERS active substrates with a well-control over the SERS performance, e.g. an ultra-high sensitivity, superior reproducibility and long-term stability remain a great challenge. Here, we introduce an easy strategy for synthesizing polydopamine-Ag microbowl/nanoparticle array (PDA-Ag MNA) substrates with a tunable superhydrophobic surface, applicable for ultra-highly sensitive SERS detection. First, the periodically dented PDA films are prepared by polymerizing dopamine onto 2D polystyrene colloidal crystals formed at the liquid/air interface, and followed with an in-situ reduction of Ag ions to Ag nanoparticles after removing polystyrene. The surface morphology, i.e. microbowl/nanoparticle structure, is well-controlled, therefore, allowing that the SERS activity of the substrate is under control. Inspired by the superhydrophobic hierarchical surface of the rose petals, this analogous MNA surface is subsequently endowed to be superhydrophobic. This way, the SERS detection of ultra-dilute solute (10−14 M) can be achieved by concentrating analytes within a localized region. Moreover, this substrate also shows a superior reproducibility in result and durability in use. This strategy exhibits a realistic paradigm for further improving the sensitivity of the SERS technique.

Hierarchical Ni(OH)2 nanotubes with ultrathin nanoflakes were successfully synthesized by a self-sacrificial template via a facile solvothermal method. The as-prepared Ni(OH)2 nanotubes exhibit a high specific capacitance of 1319 F g-1 at 3 A g-1, and retain 700 F g-1 (79.3% of the initial capacitance) at 5 A g-1 after 7000 cycles.

A joint in the medium has a significant impact on the propagation of explosion stress wave and the growth of explosion-induced crack. In this work, the crack growth experiment in the PMMA(polymethyl methacrylate) medium with vertical open joints under explosion loading was first carried out on the digital laser dynamic caustics experimental system (DLDC), in order to analyze the crack initiation, growth and arrest of wing cracks, and examine how the DSIF(dynamic stress intensity factor) at crack tip and the velocity of crack growth changed. The process of stress wave propagation and crack growth in this experiment was effectively inverted using the discrete lattice spring model (DLSM), the stress changes at the midpoint and endpoint of the joint were compared, and the acting characteristics of stress wave were analyzed here. Finally, the differences in velocity and acceleration of crack growth of wing cracks were compared and examined under different dip angles of joints.

The explosion loading testing system of digital laser dynamic caustics was performed to analyze the dynamic fracture effect of blasting detonation crack of different charge structures, and to examine the directional fracture-controlled blasting mechanism of slotted cartridge. The explicit dynamics analysis code LS-DYNA was used to simulate the slotted cartridge blasting and the generation of initial crack, and the relation between decoupling coefficient and blasting damage was also investigated. The finding shows that when the decoupling coefficient α1 equals 1.67, the fracture effect of slotted cartridge is optimal; the propagation velocity and the dynamic stress intensity factor of the detonation primary crack show a downward trend with oscillation, and reach a smaller peak in the middle and late stage of crack propagation; the plasticine medium as the buffer between the explosion product and the walls of borehole transfers energy well. The dynamic energy release rate values of the secondary crack as a whole is less than that of two primary cracks. When the decoupling coefficient is smaller than 1.67, the gas pressure, accelerated speed and velocity peak on the point of borehole walls in the slotted direction parallel to the detonation point will rapidly decrease with the increase of decoupling coefficient, but when the decoupling coefficient is greater than 1.67, these parameters will slowly decrease with the increase of decoupling coefficient.

The influence of original prefabricated empty hole on dynamic crack propagation was studied. The dynamic behavior of crack propagation due to the impacting of drop hammer on the defective PMMA medium of manufactured hole defect (different extent of left shift, respectively, for L = 110 mm, L = 111.25 mm and L = 112.5 mm) was conducted using the test system of digital laser dynamic caustics (DLDC). The stress intensity factor and velocity at the running crack tip were analyzed. Moreover, the recently developed distinct lattice spring model (DLSM) was validated using the experimental data. It was found that the numerical modeling can reproduce the experimentally observed phenomena. Combining the experimental and numerical results, it can be concluded that the influence of empty hole defects of brittle materials on dynamic fracturing is great.

Bone nonunion has become one of the most severe sequelae of fractures, infections, bone tumors, or revision arthroplasty owing to its high morbidity and disability rate. Recently, bone nonunion has received considerable attention from plastic surgeons. There are different treatment methods for nonunion depending on its classification according to the etiology and pathological types. Bone tissue engineering provides advanced platforms for the treatment of bone nonunion via the use of material scaffolds with sufficient mechanical strength. Meanwhile, it promotes bone regeneration and osseointegration by the addition of various growth factors or drugs. This review describes in detail the classification and leading causes of nonunion, as well as the clinical treatment methods and basic research progress, including the design of metal and bioactive material scaffolds. Future challenges in engineering, material science, and three-dimensional printing are also summarized. This article may provide new perspectives of the clinical translation for the treatment of bone nonunion by understanding the pathogenic mechanism and the rational application of bioactive scaffolds. Keywords: Material, Bone nonunion, Classification, Pathological feature, Treatment progress

The effects of low temperature gradient on dynamic mechanical properties of coal were examined through Split-Hopkinson Pressure Bar (SHPB) Dynamic Impact Experiment, the law of dynamic mechanical parameters of coal specimen changing from room temperature to negative temperature (25 °C, −5 °C, −10 °C, −15 °C, −20 °C, −30 °C, −40 °C) was analyzed, and the coal-rock stress-strain curve characteristics subject to the low temperature-impact load coupling effect was discussed. The law of the effects of different strain rates on the rock strength properties and the compressive deformation and failure was analyzed by studying the coal specimen at −15 °C. Moreover, the mechanical properties of coal specimen in saturated and dry conditions were compared, and the effects of water and water-ice phase transition on the strength properties of the corresponding coal specimen were analyzed.

Nowadays, two-dimensional (2D) nanomaterials with many fascinating physicochemical properties have drawn extensive attention as drug delivery platforms for cancer theranostics. Nevertheless, current existing 2D nanomaterial-based drug delivery systems normally undergo the bottlenecks of hash preparation process, low drug loading content and unsatisfactory therapeutic outcome. Herein, we developed a novel nanoparticles-induced assemble strategy to construct 2D nanosheets with ultra-high curcumin loading content of 59.6 % and excellent stability in water. Furthermore, a distinct photothermal effect and multimodal imaging property after polydopamine coating could be obtained, thereby leading to precise and efficient ablation of tumor in combination of curcumin-induced chemotherapy. More importantly, the design principle of our work offers novel facile strategy to assemble metal-binding drugs into 2D nanomedicine with high drug content and well-defined shapes.

Activatable theranostic agents that can be activated by tumor microenvironment possess higher specificity and sensitivity. Here, activatable nanozyme-mediated 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) loaded ABTS@MIL-100/poly(vinylpyrrolidine) (AMP) nanoreactors (NRs) are developed for imaging-guided combined tumor therapy. The as-constructed AMP NRs can be specifically activated by the tumor microenvironment through a nanozyme-mediated "two-step rocket-launching-like" process to turn on its photoacoustic imaging signal and photothermal therapy (PTT) function. In addition, simultaneously producing hydroxyl radicals in response to the high H2 O2 level of the tumor microenvironment and disrupting intracellular glutathione (GSH) endows the AMP NRs with the ability of enhanced chemodynamic therapy (ECDT), thereby leading to more efficient therapeutic outcome in combination with tumor-triggered PTT. More importantly, the H2 O2 -activated and acid-enhanced properties enable the AMP NRs to be specific to tumors, leaving the normal tissues unharmed. These remarkable features of AMP NRs may open a new avenue to explore nanozyme-involved nanoreactors for intelligent, accurate, and noninvasive cancer theranostics.

The occurrence of defects in a medium has a significant role in the transmission of blasting stress waves and the expansion of blast-caused cracks. In this study, an experiment is first conducted on the crack expansion in a polymethyl methacrylate (PMMA) medium with vertically filled defects under a blasting load by using the digital laser dynamic caustics (DLDC) testing system. The origin, expansion, and termination of wing cracks are analyzed, and the variation of the dynamic stress intensity factor and the crack expansion velocity on the crack tip are studied. An effective inversion to the stress wave transmission and the crack expansion is achieved via a test conducted using the distinct lattice spring model (DLSM), along with a comparison between the stress variation at the center points on the wave heading side, back side, and endpoints of the defect. The characteristics of the impact due to the stress wave are also analyzed. Lastly, the expansion velocity/acceleration difference between the wing cracks are analyzed and compared with various defect characteristics (filled, open, closed, bedding).

A digital laser dynamic caustics experimental system is utilized to study the dynamic characteristics of propagation of main cracks and secondary cracks in PMMA medium with flaws under explosion loads. Prefabricated through-cracks are found to open or close as a result of the explosion stress wave reflection from these flaws, which weakens the dynamic behaviors of the main cracks. These main cracks generally do not pass through prefabricated cracks and continue to propagate. Secondary cracks are generated from the ends of the prefabricated through cracks. The initiation and propagation of secondary cracks are caused by the diffraction effect of the tensile stress concentration at both tips of the flaws. The cracking angles of the secondary cracks are closely related to the prefabricated cracks and the incident angle of the explosion stress wave. The secondary cracks initiate from the direction of the maximum energy release rate, and exhibit the mixed fracture mode. The mechanical characteristic values such as the crack length, propagation velocity, and DSIF of main crack that are not directly affected by prefabricated through-cracks are much greater than the values for secondary cracks. Under explosion load, the initiation toughness is from 0.5 to 0.65 MN/m3/2, and the arrest toughness is from 0.25 to 0.35 MN/m3/2.

Blasting in rocks typically causes the remaining rock mass to be subjected to varying degrees of damage and failure, leading to a decline in the mechanical properties and bearing capacity of the surrounding rock. In this study, a decoupled charge blasting experiment for small-charge small-scale red sandstone specimens was conducted in a laboratory; the damaged specimens (after blasting) were scanned and reconstructed using computed tomography (CT) scanning and three-dimensional reconstruction technology. The relationship between the gray-scale change characteristics of the CT images and the decoupling coefficient was analyzed. Additionally, the analysis dimensions and damage degree of the damaged specimens (after blasting) were calculated and the damage degree of the indoor small-scale samples (after blasting) was quantitatively evaluated. Furthermore, the relationship between the decoupling coefficient and the blasting action was examined using the LS-DYNA simulation software. The results indicated that the gray-scale value tended to increase with the decoupled coefficient, and the decoupled coefficient demonstrated a significant influence on the blasting action. Thus, the proposed method serves as a suitable means for the evaluation of the failure mechanism through the reconstruction of the spatial distribution of internal cracks.

In this paper, the dynamic fracture experiment of half-circular disk PMMA specimens with prefabricated penetration defects under impact loading was carried out on the digital laser dynamic caustics experimental system (DLDC), the law of crack initiation, growth and traversing under different tilt angles (30°, 45°, 60°) was examined, and the variations of crack growth trajectory, velocity and DSIF at crack tip were compared for analysis. In addition, the discrete lattice spring method (DLSM) as a new development was employed to simulate how the dynamic cracks grew in PMMA specimens with defects, it was found that the numerical model can reproduce the experiment phenomenon. On the basis, the effect of the elastic modulus of the penetration defect medium on crack growth was analyzed. Referring to the experiment and numerical results, it was thus concluded that the angle and the elastic modulus of penetration defect would dramatically influence the crack growth characteristics.

In this study, based on an experimental digital laser dynamic caustic system, a dynamic fracture experiment on a polymethyl methacrylate (PMMA) semi-disc specimen with a weak precast double-layer surface under an impact load was carried out, the cracking, expansion, and wearing patterns of the cracks under different tilt angles (60°, 45°, and 30°) were studied, and the changing characteristics of the trajectory, velocity, and dynamic stress intensity factors of a crack expansion were compared. In addition, a newly developed discrete lattice spring method was adopted to simulate the expansion of dynamic cracks in a PMMA specimen with weak double-layer surfaces, and it was found that this numerical model can reproduce experimental phenomena for analyzing the effects of a weak surface spacing on the crack expansion. Combined with the test and numerical analysis results, it can be concluded that the tilt angle and spacing of a weak double-layer surface will have a significant influence on the crack expansion characteristics.

Janus particles with controlled asymmetries and functionalities represent promising building blocks and functional materials due to their unique anisotropic features. Herein, we show a facile and general approach towards preparing colloidal Janus particles with adjustable surface asymmetries and functionalities based on monolayer colloidal crystal (MCC) templates combined with mussel-inspired polydopamine (PDA) chemistry at an air-water interface. First, monodisperse colloidal polystyrene/polydopamine (PS/PDA) Janus particles with tunable asymmetrical geometries are synthesized by polymerizing dopamine onto two-dimensional (2D) polystyrene (PS) monolayer colloidal crystals formed at the air-water interface. Moreover, the good chemical reactivity of the PDA coating makes it a versatile platform to introduce a variety of functional materials, e.g., metal nanoparticles and organic molecules, producing colloidal Janus particles with adjustable functionalities. Finally, we demonstrate this synthetic strategy not only provides a controllable method for the fabrication of monodisperse colloidal Janus particles but also opens up a new Janus platform for artificially designed Janus particles with tunable asymmetries and functionalities.

Development of functional theranostic platform for systemic contrast-enhanced diagnostic imaging and therapy is of great necessity in nanomedicine. However, synthesizing the biocompatible theranostic agents with enhanced merits in imaging and therapy via a facile and green way is still highly challenged. Here, we report a novel theranostic agent based on colloidal polydopamine/Au (PDA/Au) hollow spheres, which are synthesized with combined use of PDA chemistry and sacrificial template techniques. Colloidal polystyrene (PS) spheres serve as the templates with coatings of a PDA shell and Au nanoparticles in sequence, which are subsequently removed with trichloromethane, giving rise to colloidal PDA/Au hollow spheres. Colloidal PDA/Au hollow spheres exhibit excellent contrast enhancement for ultrasound imaging, and can serve as the near-infrared (NIR) photoabsorbers for the effective photothermal ablation of 4 T1 breast cancer cells in vitro with minor cytotoxicity to living cells. This method suggests a novel avenue for theranostic treatment in oncology.

It is imperative to develop efficient and environmentally friendly oil-spill cleanup materials to solve the problems raised by frequent oil spillages and industrial discharge of organic solvents. Here, we present a bioinspired one-step construction of hierarchical superhydrophobic surfaces on various commercial porous materials by immersing the materials into an alkaline aqueous mixture consisting of dopamine (DA) and dodecyltrimethoxysilane (DTMS). The self-polymerization of DA constructs the bumpy surfaces, while the DTMS coatings enhance the hydrophobicity of the surfaces. The combined use of both results in the hierarchical superhydrophobic surfaces. This surface modification of porous materials allows them as the potential candidates for collecting a wide variety of oils/organic solvents from water in a highly efficient, recyclable, and durable way. This approach proposes a general, yet green path for constructing superhydrophobic surfaces, which can be further adapted to prepare economic oil/organic solvents absorbents applied in the fields of oil/water separation, wastewater remediation, and organics recovery.

Graphene nanowalls (GNWs) have been synthesized on diamond particle surface by a simple heat-treatment process in vacuum induction furnace. The thickness of the as-grown GNWs is in the range of 20–40 nm, and most of the nanowalls are smooth and flat. The growth of GNWs is affected by the type of catalyst and treatment temperature, and the mixed catalytic effect of Fe and Ni is better than Fe or Ni respectively. High-density GNWs was grown on the diamond particle entire surface, when the heat treatment process is performed at 1473 K. Al/diamond composites with high thermal conductivity of 423 W/(m K) was obtained, which was achieved by the formation of large number of GNWs on the diamond particle surface. Systematic analyses reveal that the growth models such as classic precipitation upon cooling (PUC) model are not applicable to explain this kind of GNW’s growth mechanism. Hereby, an extended PUC model is proposed to interpret the GNW’s growth process on diamond surface.

A kind of embedded impedance-based piezoelectric sensor was fabricated by using mixture of cement powder and epoxy resin as packaging layer. Effects of temperature and load on impedance and conductance spectra of the sensor were investigated. The results show that the baseline of conductance spectra shifts with increasing temperature, and the resonance peaks in the conductance spectra show obvious temperature dependence. The impedance spectra of the embedded sensor under external load from different direction was discussed. The results indicate that the sensor is sensitive to the initial load when the external load is parallel to the thickness direction of the sensor. When the load is along the planar direction of the sensor, the impedance spectra of the sensor show good correlation with the load variation. The root mean square deviation (RMSD) index was also employed here to intuitively indicate the impedance variation of the embedded PZT sensor under temperature and load.

Chlorinated butyl rubber composites were prepared by a compounding and vulcanizing process using phenolic resin (PF) as the vulcanizing agent and carbon black as filler. Instead of using the conventional vulcameter method to determine the vulcanizing parameters, the vulcanization temperature and time were obtained by differential scanning calorimetry (DSC) and tensile testing, respectively. Dynamic mechanical analysis (DMA) showed that, higher PF content resulted in higher E′ and lower tanδ, and variations of E′ and tanδ with temperature were consistent with the time-temperature equivalence principle. It is proposed that chlorinated butyl rubber using phenolic resin as the vulcanizing agent could be used as potential damping materials in the temperature range 20–100°C and frequencies 0.1–100 Hz.

Combination of photodynamic therapy (PDT) and photothermal therapy (PTT) generally requires different components to build a composite irradiated with different excitation lights. One component photoactive agent for enhanced combination of PDT and PTT under the excitation of a single wavelength light source is more urgent in tumor phototherapy via adjusting spatial arrangement of photoactive units. Herein, porphyrin-based covalent organic framework nanoparticles (COF-366 NPs) were synthesized to control the orderly spatial arrangement of the photoactive building units and firstly used for antitumor therapy in vivo. COF-366 NPs provide the simultaneous therapy of PDT and PTT under a single wavelength light source with the monitoring of photoacoustic (PA) imaging, which makes the operation simpler and more convenient. COF-366 NPs had achieved good phototherapy effect even in the face of large tumors. The prepared multifunctional COF-366 NPs open up a new avenue to phototherapeutic materials and expand the application range of covalent organic framework.

A series of silica nanoscale materials(NIMs) were prepared through a facile acid-base neutralization. These silica derivatives consist of a nanosilica core, a charged corana(sulfonic acid SIT) attatched to the core, and an oppositely charged canopy (PEG-substituted tertiary amines) to balance the corona. By selecting proper canopy such as surface-functionalized, silica can behave viscous liquid in the absence of any solvent at room temperature. DSC results indicated the melting temperature and glass transition of the derivatives were slightly lower than those of the neat polymer canopy, indicating strong interaction between the core and PEG-substituted tertiary amine.

The crack propagation behaviours of polymethyl methacrylate material with double holes under the directional controlled blasting are studied using dynamic caustic method. A series of dynamic caustic patterns at the propagating crack tip under the explosive loading are recorded using the digital high-speed camera. Some important dynamic fracture characterizations and parameters about two main cracks are determined including the crack path, the propagating speed and the crack tip stress intensity factors. The fracture mechanisms of the double blasting holes are analysed. The results provide the important experimental basis for evaluating and designing the directional controlled blasting for the rock tunnel and the rock face excavation.

In this work, fumed silica treated with two kinds of orgnosilanes, γ-Aminpropyltriethoxysilane(KH550) and 3-Trimethoxysilylpropyldimethyloctadecyl ammonium Chloride(AEM5700), were synthesized. Then a series of silica/epoxy composites were prepared by casting molding. The effects of silica dispersion and loading on the mechanical properties were discussed. Results showed that compared with AEM 5700 modified silica/epoxy, tensile properties of KH550 modified silica/epoxy composites was significantly increased. Both composites reached their maximum mechanical properties at 3% silica loading. SEM indicates compared with neat silica/epoxy composites, both orgnosilanes modified silica/epoxy dispersed more evenly in EP matrix.

In situ amendments are a promising approach to enhance removal of metal contaminants from diverse environments including soil, groundwater and sediments. Apatite and chitin were selected and tested for copper, chromium, and zinc metal removal in marine sediment samples. Microbiological, molecular biological and chemical analyses were applied to investigate the role of these amendments in metal immobilization processes. Both apatite and chitin promoted microbial growth. These amendments induced corresponding bacterial groups including sulfide producers, iron reducers, and phosphate solubilizers; all that facilitated heavy metal immobilization and removal from marine sediments. Molecular biological approaches showed chitin greatly induced microbial population shifts in sediments and overlying water: chitin only, or chitin with apatite induced growth of bacterial groups such as Acidobacteria, Betaproteobacteria, Epsilonproteobacteria, Firmicutes, Planctomycetes, Rhodospirillaceae, Spirochaetes, and Verrucomicrobia; whereas these bacteria were not present in the control. Community structures were also altered under treatments with increase of relative abundance of Deltaproteobacteria and decrease of Actinobacteria, Alphaproteobacteria, and Nitrospirae. Many of these groups of bacteria have been shown to be involved in metal reduction and immobilization. Chemical analysis of pore and overlying water also demonstrated metal immobilization primarily under chitin treatments. X-Ray absorption spectroscopy (XAS) spectra showed more sorbed Zn occurred over time in both apatite and chitin treatments (from 9% - 27%). The amendments improved zinc immobilization in marine sediments that led to significant changes in the mineralogy: easily mobile Zn hydroxide phase was converted to an immobile Zn phosphate (hopeite). In-situ amendment of apatite and chitin offers a great bioremediation potential for marine sediments contaminated with heavy metals.

BACKGROUND Different extents and locations of acetabular cartilage defect have been supposed to be a major cause of undesirable outcomes of periacetabular osteotomy (PAO) in patients with developmental dysplasia of the hip (DDH). This study aimed to verify whether different locations of cartilage deficiency affect the biomechanical environment in a three-dimensional model utilizing finite element analysis (FEA). MATERIAL AND METHODS We developed 3 DDH models - DDH-1 (normal shape), DDH-2 (superior defect), and DDH-3 (anterosuperior defect) - by deforming from a normal hip model. We also developed 3 PAO models - PAO-1, PAO-2, and PAO-3 - through rotating osteotomized fragments. RESULTS The maximum von Mises stress in the normal hip was 13.06 MPa. In the DDH-1 model, the maximum value on the load-bearing area decreased from 15.49 MPa pre-PAO to 14.28 MPa post-PAO, while stresses in the DDH-2 and DDH-3 models were higher than in the DDH-1 model, both pre-PAO and post-PAO (30.46 MPa to 26.04 MPa for DDH-2; 33.89 MPa to 27.48 MPa for DDH-3). CONCLUSIONS This study shows that, both pre- and post-PAO, different types of cartilage deficiency affect the biomechanical environment. Furthermore, in dysplastic hips, obtaining accurate three-dimensional information about the acetabular cartilage can contribute substantially to PAO decision making.

Frequent oil spillages and industrial discharge of oils/organic solvents have induced severe environmental pollution and ecological damage, and a great cost in energy and finance has been consumed to solve the problems raised. Therefore, it is urgent to develop a surface hydrophobic modification that can be applied to materials with desired properties of high separation efficiency, excellent selectivity and stable performance in extreme conditions during the oil/water separation. Herein, with combined bioinspirations from mussel adhesive protein (polydopamine) and superhydrophobic lotus leaf (hierarchical structures), we develop a general way to superhydrophobically modify various commercial materials, aiming for the selective removal of oils/organic solvents from water. In this procedure, immersing commercial materials (e.g. melamine sponge, stainless steel mesh, nylon netting and cotton cloth) into water/ethanol/ammonia mixtures at a low concentration of dopamine (DA, 2 mg/mL) allows a polydopamine (PDA) coating with a tunable roughness appearing on the substrate in one step. This is because DA can self-polymerize and form PDA particles with a catalyst of ammonia, attaching to any surfaces due to abundant catechol and amine groups in PDA, and ultimately, resulting in hierarchical structures. The subsequent decoration with 1H, 1H, 2H, 2H-perfluorodecanethiol features the surface superhydrophobic and superoleophilic. This approach is straightforward and economic, and carried out under a mild, environmental-benign circumstance, with nonspecific substrate demands. In addition, the as-prepared superhydrophobic materials exhibit excellent separation performances including high absorption/separation capacity, excellent selectivity, and extraordinary recyclability for collecting various oils/organic solvents from water. These superhydrophobic materials have also verified to be highly chemical resistant, environment stable and mechanically durable. Therefore, this simplicity and versatility of the direct mussel-inspired approach may facilitate the fast development of oil/water separation materials for applications in the field of water remediation, clean-up of oil spills and oil recovery.

Mica/glass fiber-reinforced epoxy with 0° and 45° ply angle were prepared by hand lay-up and the mechanical and damping properties were studied. Results show that the addition of mica resulted in decrease of tensile strength and modulus for both composites. Althogh flexural strength and modulus of composites with 45° appeared a maximum at 5 phr mica loading, that of composites with 0° reached a maximum at 10 phr mica loading. For composites with 0°, damping ratio reaches maximum at 5 phr mica. Although for composites with 45°, damping ratio decrease with increasing mica loading.

The direct electrochemistry of horseradish peroxidase (HRP) on a novel sensing platform modified glassy carbon electrode (GCE) has been achieved. This sensing platform consists of Nafion, hydrophilic room-temperature ionic liquid (RTIL) and Au nanoparticles dotted titanate nanotubes (GNPs-TNTs). The composite of RTIL and GNPs-TNTs was immobilized on the electrode surface through the gelation of a small amount of HRP aqueous solution. The composite was characterized by transmission electron microscopy (TEM), powder X-ray diffraction (XRD) and infrared spectroscopy (IR). UV-Vis and IR spectroscopy demonstrated that HRP in the composite could retain its native secondary structure and biochemical activity. The HRP-immobilized electrode was investigated by cyclic voltammetry and chronoamperometry. The results from both techniques showed that the direct electron transfer between the nanocomposite modified electrodes and heme in HRP could be realized. The biosensor responded to H(2)O(2) in the linear range from 5×10(-6) to 1×10(-3) mol L(-1) with a detection limit of 2.1×10(-6) mol L(-1) (based on the S/N=3).

The composites based on conductive carbon black (CCB) and piezoelectric ceramic particles, PMN, and chlorobutyl rubber (CCB/PMN/IIR) were prepared by compounding and vulcanizing process. Microstructure, mechanical, dynamic mechanical and electrical properties of CCB/PMN/IIR with various CCB and PMN loading were measured by SEM, mechanical tests, and electrical analysis. The results show tensile properties decrease with increasing PMN loading, while showed a maximum value with CCB loading. Tanδmax increased and the glass transition broadened for composites with 50 wt% PMN and 25 wt% CCB. The electric resistance decreased with CCB loading. The piezoelectric damping theory was used to explain the experimental results. The three-phase composites with proper composition can be used as high damping polymer materials.

The testing system of digital laser dynamic caustics was performed here to examine the super-dynamic fracture mechanics of directional blasting crack, which, using an irregular shape cartridge, revealed the rock breaking mechanism of directional fracture blast. The findings show that the blasting primary crack fracture features—the typical tensile break, the variation trend of the dynamic stress intensity factor (DSIF), crack propagation velocity, and crack length— were more or less the same, the primary crack fracture was finished during 60–200 μs, the limit DSIF scarcely exceeded 1.5 MN/m3/2, and the arrest toughness of the blasting fracture was about 0.3 MN/m3/2. The irregular shape cartridge showed significant detonation wave unloading effects and detonation gas jet effects in the accumulative direction or slotting direction; the “air wedge effect” of the high-pressure detonation gas jet acted as the main drive for further expansion of the compression radial crack in the accumulative direction (or slotting direction), which also held the propagation of the compression radial crack in the nonaccumulative or nonslotting direction). Additionally, the accumulative cartridge and slotted cartridge were applied to the construction field, and it was found that the directional fracture blast was enabled, the good blasting fracture surface was formed, and better economic benefits and less operation time could be achieved using these two cartridges.

Flame retardant epoxy resins were prepared by a simple mixed method using ammonium aluminum carbonate hydroxy hydrate (AACHH) as a halogen-free flame retardant. The prepared samples were characterized by X-ray diffraction, thermogravimetric and differential scanning calorimetry, scanning electron microscope and limiting oxygen index(LOI) experiments. Effects of AACHH content on LOI of epoxy resins/AACHH composite and flame retardant mechanism were investigated and discussed. Results show that AACHH exhibites excellent flame-retardant properties in epoxy resin(EP). When the content of AACHH was 47.4%, the LOI of EP reached 32.2%. Moreover, the initial and terminal decomposition temperature of EP increased by 48°C and 40 °C, respectively. The flame retarded mechanism of AACHH is due to the synergic flame retardant effects of diluting, cooling, decomposition resisting and obstructing.

The dynamic mechanical behavior of a new kind of flexible epoxy FE-1, which was crosslinked under four different thermal crosslink conditions, was studied. Dynamic mechanical measurement was carried out from 10℃ to 120℃, and loss factor, tanδ and the storage modulus as functions of temperature were presented under five different frequencies of 0.1 Hz, 1 Hz, 5 Hz, 50 Hz and 100 Hz. The experimental results show that temperature has dramatic effects on the dynamic mechanical behavior of flexible epoxy. Compared with other common available epoxy, the flexible epoxy has higher loss factor over broad frequency and common temperature range. Activation energy corresponding to glass transition process of FE-1 was calculated from the temperature corresponding to tan δ(subscript max) values, obtained at different measurement frequencies. The maximum value of loss factor is 0.75 and the T(subscript g) varies from 6℃ to 50℃, indicating the flexible epoxy can be used as damping polymer materials at common temperature or frequency range.

Conductive composite foams were prepared by exposing iodine-loaded polyurethane (PU) foams to pyrrole vapor. The kinetics, equilibrium, and mechanism of the in situ polymerization of pyrrole by iod...

A novel approach is reported for cell patterning based on addressable microheaters and a poly(N-isopropyl acrylamide) (pNIPAM) themoresponsive coating. This thermoresponsive coating is created by a radio frequency NIPAM plasma and is denoted as plasma polymerized NIPAM (ppNIPAM). Films of ppNIPAM with a good retention of monomer side-chain functionality are produced using low-power continuous plasma deposition. Cell adhesion and cell detachment tests indicate that the surface switches between adhesive and nonadhesive behaviors as a function of temperature. The use of a photolithographically fabricated microheater array allows the ppNIPAM transition to occur spatially under the control of individual heaters. This localized change in the surface adhesive behavior is used to direct site-specific cell attachment. Patterned adhesion of two types of cells has been visualized on the array through fluorescent markers. Applications for diagnostic devices, cell-based sensors, tissue engineering, and cell transfection are envisioned. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 70A: 159–168, 2004