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An environment friendly water-soluble carboxymethyl chitosan/carboxyl group of multi-walled carbon nanotubes (WSCC/MWCNTs-COOH) composite was prepared by using carboxyl group of multi-walled carbon nanotubes (MWCNTs-COOH) and aqueous carboxymethyl chitosan (WSCC) solution. The WSCC/MWNTs-COOH composite was used as an adsorbent to adsorb Pb(II) in water via non-covalent adsorption interaction. In the batch adsorption experiments, the optimal adsorption conditions and maximum adsorption efficiency were determined by investigating the influence of adsorbent concentration, contact time and Pb(II) initial concentration, respectively. This study will provide a novel adsorbent for detection and removal of harmful Pb(II) residues in water.

Nanocomposites play a key role in the removal of toxic metal(loid)s from environmental water. In this study, we investigated the adsorption capability of water-soluble carboxymethyl chitosan (WSCC)-modified functionally oxidized single walled carbon nanotubes (oSWCNTs) for rapid and efficient removal of toxic Pb(ii) from water. The WSCC-oSWCNTs nanocomposite was prepared by an acid treatment of SWCNTs followed by an ultrasonic dispersion process using WSCC as dispersant. The morphology and chemical characteristics of the WSCC-oSWCNTs nanocomposite were further identified using various characterization techniques (

The stability of a dispersion solution was evidenced by images of oMWCNTs-dispersed by N,O-CMCS before (b) and after (a). UV-vis further showed that individual oMWCNTs were enriched via the non-covalent interaction between oMWCNTs and N,O-CMCS.

Fiber-reinforced composites (FRCs) under transverse impact by bullets are demonstrated to be subjected to the multi-axial stress state. This study presents the dynamic behavior of unidirectional composites at confining pressure. An S-2 glass/SC- 15 composite laminate was manufactured by using a resin injection method and then sectioned into small cylindrical specimens. Optical microscopy was utilized for specimen characterization and the fiber volume fraction was measured. Dynamic experiments were conducted by using a conventional Kolsky compression bar modified by adding a radial and axial confining chamber. Prior to the dynamic loading, hydraulic pressure up to 50 MPa was applied to the two chambers simultaneously. The radial chamber enclosed the cylindrical composite specimen and applied the radial confining pressure. On the other hand, the axial chamber was added at the free end of the transmission bar, providing the axial portion of the hydrostatic pressure to the specimen. Once the triaxial confinement was achieved, a striker impacted the incident bar to apply a dynamic compressive load to the specimen. The specimens’ dynamic responses were compared with that without confining pressure. It is found that the peak strength of the composite increased as the confining pressure increased.

Compassion fatigue can negatively affect not only healthcare professionals' physical and mental health but also the quality of care they provide and organizational outcomes. However, little is known about compassion fatigue among Chinese midwives working in the delivery room. This study aimed to examine compassion fatigue and compassion satisfaction levels among Chinese midwives working in the delivery room and correlate their compassion fatigue and compassion satisfaction.A multisite cross-sectional study with a convenience sampling approach was conducted at 62 hospitals in Henan Province, central China, from May to July 2020. The participants were recruited through an online survey. A self-designed sociodemographic and work-related data sheet, the Social Support Rating Scale (SSRS), and the Professional Quality of Life Scale (ProQoL) were used to measure the participants'basic information, level of social support, compassion fatigue(consists of burnout and secondary traumatic stress) and compassion satisfaction. Descriptive analysis was used to describe the characteristics of the participants' social support, compassion fatigue and compassion satisfaction. Multiple linear regression analysis was employed to identify associations with the participants' sociodemographic and professional characteristics, compassion fatigue and compassion satisfaction.A total of 213 questionnaires were completed, 206 of which were valid (96.71%). The majority of the participants reported moderate risks for compassion satisfaction (75.24%) and burnout (59.71%) and low risks for secondary traumatic stress (61.65%). Higher job satisfaction as a midwife, lower average working hours per week in the past year, higher social support, extroverted personality, and work recognition in the past month were positively associated with compassion satisfaction, explaining 48.7% of the total variance. Always considering giving up a midwifery career, lower social support, working a day-night shift, poor health condition, more exposure to traumatic birth events per month on average in recent years, and lower job satisfaction as a midwife were negative factors for burnout, explaining 35.3% of the total variance. Four factors, including more exposure to traumatic birth events per month on average in recent years, always considering giving up a midwifery career, working a day-night shift and poor sleep quality, were negatively related to secondary traumatic stress, explaining 14.2% of the variance.In this study, midwives showed moderate levels of compassion satisfaction and burnout and low levels of secondary traumatic stress which should attract the attention of health institutions. A healthy and supportive work environment is crucial to midwives' health, well-being and job satisfaction. Tailored strategies such as trauma management, emotional literacy, peer and social support networks should be implemented to support midwives' compassion satisfaction, while prevent and lower midwives' burnout and secondary traumatic stress.

We experimentally determined the uniaxial compressive stress-strain responses of an auxetic polyurethane (PU) foam at quasi-static (0.01/s), intermediate (1/s, 10/s and 745/s) and high (1430/s, 1870/s and 2290/s) strain rates. A hydraulically driven materials testing system (MTS) was used to perform the experiments at the strain rate of 0.1/s, 1/s and 10/s, while higher intermediate (745/s) and high strain-rate compressive loadings were introduced using long and regular Kolsky bars, respectively. The Poisson effect of the auxetic PU foam was also investigated during the experiments using a precision LED optical micrometer system (OMS) (0.01/s–10/s) or an ultra-high speed camera (745/s–2290/s). Our results show that the compressive stress-strain curves of the auxetic PU foam are non-linear and strain-rate sensitive. In all the experiments, the Poisson's ratio, with an initial negative value at small strains, progressively increased toward 0 as the specimen was further compressed. The strain-rate effect on the material's Poisson's ratio is also evident in our study, as the specimens subjected to high strain-rate loadings exhibited smaller negative Poisson's ratios (NPR) in absolute sense at small strains in comparing with those at quasi-static and intermediate strain rates.

We developed a microscopic experimental method that transversely loads and images single high-performance fibers. The experimental set-up was inside the chamber of a scanning electron microscope (SEM). Force and displacement histories were recorded by the loading device. The SEM enabled in-situ observation of the fiber’s initial contact with the transverse indenter and subsequent deformation, crack initiation and propagation until the final failure. Within the loading device, fiber gauge length, indenter tip radius and loading direction can be varied as desired. To demonstrate the new experimental capability, initial results for a razor blade transversely cutting a Dyneema® SK76 fiber are presented in this paper. To avoid the effect from the conductive coating on the mechanical behavior of the fiber, a low vacuum detector was adopted to capture the deformation and failure of an uncoated fiber. These experiments revealed the damage and failure processes of single fibers with high-resolution micrographs.

Purpose Many approaches have been described to accomplish tendon reattachment to the radial tuberosity in a distal biceps tendon rupture, with significant success, but each is associated with potential postoperative complications, including posterior interosseous nerve (PIN) injury. To date, there has been no consensus on the best approach to the repair. The purpose of this study was to evaluate the supination strength and the distance of drill exit points from the PIN in a power-optimizing distal biceps repair method and compare the findings with those of a traditional anterior approach endobutton repair method. Methods Cadaveric arms were dissected to allow for distal biceps tendon excision from its anatomic footprint. Each arm was repaired twice, first with the power-optimizing repair using an anterior single-incision approach with an ulnar drilling angle and biceps tendon radial tuberosity wraparound anatomic footprint attachment, then with the traditional anterior endobutton repair. Following each repair, the arm was mounted on a custom-built testing apparatus, and the supination torque was measured from 3 orientations. The PIN was then located posteriorly, and its distance from each repair exit hole was measured. Results Five cadaveric arms, each with both the repairs, were included in the study. On average, the power-optimizing repair generated an 82%, 22%, and 13% greater supination torque than the traditional anterior endobutton repair in 45° supination, neutral, and 45° pronation orientations, respectively. On average, the power-optimizing repair produced drill hole exit points farther from the PIN (23 mm) than the traditional anterior endobutton repair (14 mm). Conclusions The power-optimizing repair provides a significantly greater supination torque and produces a drill hole exit point significantly farther from the PIN than the traditional anterior endobutton approach. Type of study/level of evidence Therapeutic III.

Glutathione (GSH) and glutathione-S-transferases (GSTs) are two frontlines of cellular defense against both acute and chronic toxicity of xenobiotics-induced oxidative stress. The contribution of GSH and GST enzymes to signaling pathways and the regulation of GSH homeostasis play a central role in the detoxification of numerous environmental toxins and impurities. Iron oxide nanoparticles stemmed from traffic exhaust, steel manufacturing, or welding as a potential environmental pollution can lead to adverse respiratory outcomes and aggravate the risk of chronic health conditions via persistent oxidative stress. In this work, two kinds of acute exposure experiments of iron oxide (Fe2O3 and Fe3O4) nanoparticles in cells and in vivo were conducted to evaluate the GSH levels and GST activity. Our current research presented Fe3O4 nanoparticles at lower concentrations (≤100 μg/ml) seem to be more toxic to the human bronchial epithelial cells as their consumption of GSH and decrease of GST activity. The catalysis activity of Fe3O4 nanoparticles per se may contribute to the intracellular GSH consumption along with inhibition of glutathione-S-transferase class mu 1 and P (GSTM1 and GSTP1) active site and expression decrease of GSTM1 and GSTP1. Accordingly, the GSH consumption and decrease in GST activity directed to the further lipid peroxidation regarded as an earlier marker for toxicity evaluation of iron oxide nanoparticles, and relevant intervention may be effective for prevention of respiratory exposure induced damage from iron oxide nanoparticles.

Ferroptosis is an iron-dependent cell death caused by excessive peroxidation of polyunsaturated fatty acids. It can be activated by iron-based nanoparticles as a potential cancer therapeutic target. However, the intracellular transformation of iron-based nanoparticles is still ambiguous and the subsequent ferroptosis mechanism is also obscure. Here, we identified the time-course metabolism of ultrasmall superparamagnetic iron oxide nanoparticles (USPIO) in cells by using X-ray absorption near edge structure spectroscopy. Also, the integrated quantitative transcriptome and proteome data obtained from the cells exposed to USPIO exhibited hallmark features of ferroptosis. With the chemical species of iron oxide transforming to ferritin, the intracellular GPX4 down-regulated, and lipid peroxide began to accumulate. These results provide evidence that the intracellular metabolism of USPIO induced ferroptosis in a time-dependent manner, and iron over-loaded in cytoplasm along with lipid peroxidation of the membrane are involved in the detailed mechanism of ferroptosis signaling activation.

Background Among manufactured or engineered nanoparticles, carbon black (CB) has largest production worldwide and is also an occupational respiratory hazard commonly seen in rubber industry. Few studies have assessed the risk for cardiovascular disease in carbon black exposed populations. An endothelial biosensor assay was used to quantify the capacity of sera from 82 carbon black packers (CBP) and 106 non-CBPs to induce endothelial cell activation ex vivo. The mediation effect of circulatory proinflammatory factors on the association between carbon black exposure and endothelial cell activation was assessed and further validated using in vitro intervention experiments. Results The average elemental carbon level inside carbon black bagging facilities was 657.0 μg/m3, which was 164-fold higher than that seen in reference areas (4.0 μg/m3). A global index was extracted from mRNA expression of seven candidate biosensor genes using principal component analysis and used to quantify the magnitude of endothelial cell activation. This global index was found to be significantly altered in CBPs compared to non-CBPs (P P = 0.74). Individual gene analyses identified that de novo expression of key adhesion molecules (e.g., ICAM and VCAM) and chemotactic factors (e.g., CCL2, CCL5, and CXCL8) responsible for the recruitment of leukocytes was dramatically induced in CBPs with CXCL8 showing the highest fold of induction (relative quantification = 9.1, P Conclusions Inflammatory mediators in sera from CBPs may bridge carbon black exposure and endothelial cell activation response assessed ex vivo. CBPs may have elevated risk for cardiovascular diseases when comorbidity exists. Our study may serve as a benchmark for understanding health effects of engineered carbon based nanoparticles with environmental and occupational health relevance.

Amyloid-like fibrils are prepared from protein in the lab by controlled heat treatments, yet these must be further assembled to match the desirable mechanical and structural properties of biological fibers. Here, β-lactoglobulin fibrils were incorporated into poly(ethylene oxide) fibers of 40-180 nm diameter by electrospinning. Protein fibrils presented as short segments dispersed within electrospun fibers, with no change in fibril diameter after electrospinning. Imaging analysis revealed fibrils were aligned within 20° relative to the fiber long axis, and alignment was further confirmed by polarized FTIR and anisotropic SAXS/WAXS scattering patterns. The elastic modulus of fibers increased with protein fibril content from 0.8 to 2 GPa, which is superior to reported values of silk, collagen, and gelatin. The present setup allows for manufacture of large quantities of polymeric fibers containing protein fibrils with varied diameter and mechanical strength, endowing great potential for a variety of applications.

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This paper demonstrates the effectiveness of parametrically-upscaled continuum damage mechanics (PUCDM) models for multiscale damage analysis of S-2 glass fiber/SC-15 epoxy matrix composite beams subjected to single-edge notched bending (SENB) tests. The SENB experiments with [ 0 12 / 9 0 12 ] double-ply and [ 0 8 / 9 0 8 / 0 8 ] triple-ply composite beams use synchrotron X-ray phase-contrast imaging for in-situ damage characterization. PUCDM models represent a class of thermodynamically-consistent multiscale constitutive models that bridge length-scales through explicit incorporation of representative aggregated microstructural parameters (RAMPs) in constitutive coefficients. Functional forms of RAMPs are generated through machine learning tools, operating on a micromechanical analysis database. The efficient PUCDM-based FE simulations reveal multiscale damage phenomena in the SENB experiments.

Background The “secondary injury” theory of liver failure indicated that hyperammonaemia due to liver failure causes further deterioration of hepatocytes. Our previous studies have demonstrated that high blood ammonia levels may lead to hepatocyte apoptosis, as NH4Cl loading caused metabolic acidosis and an increase in sodium-hydrogen exchanger isoform 1 (NHE1). In this study, we established a hyperammonia hepatocyte model to determine the role of NHE1 in the regulation of hepatocyte apoptosis induced by NH4Cl. Materials and methods In current studies, intracellular pH (pHi) and NHE1 activity were analyzed using the pHi-sensitive dye BCECF-AM. The results showed that intracellular pH dropped and NHE1 activity increased in hepatocytes under NH4Cl treatment. As expected, decreased pHi induced by NH4Cl was associated with increased apoptosis, low cell proliferation and ATP depletion, which was exacerbated by exposure to the NHE1 inhibitor cariporide. We also found that NH4Cl treatment stimulated PI3K and Akt phosphorylation and this effect was considerably reduced by NHE1 inhibition. Conclusion This study highlighted the significant role of NHE1 in the regulation of cell apoptosis induced by hyperammonaemia.

A water soluble polysilane derivative, polymethyl(crylic acidyl)silane, has been synthesized by the hydrosilylation of crylic acid with polymethylsilane using 2,2′-azobisisbutyronitrile as initiato...

Owing to their unique physical and mechanical properties, carbon fiber reinforced plastics (CFRPs) are finding wide applications in a variety of industries. This broad application necessitates a consideration of the material response in nontraditional environments to evaluate their overall reliability. In the current study, we investigate the time-dependent behavior of unidirectional [0°]6 CFRPs irradiated by a short pulse Nd:YVO4 near-infrared laser for durations ranging between 100 and 500 ms. Post irradiation, the damage on the surface was characterized using optical and electron microscopy as well as optical surface profilometry. Qualitatively, the heat-affected zone (HAZ) was found to primarily consist of an out-of-plane expansion and anisotropic matrix removal with no structural damage to the fibers. The growth in HAZ size is conduction dependent and has a rapid trajectory along the fiber direction and a subdued trajectory along the transverse direction. Further evaluation of the subsurface via x-ray micro-CT showed the HAZ to be surface localized. An analytical heat conduction approach was also used to understand the evolution of surface HAZ with exposure time. This simplified approach was found to adequately capture the shape and growth of the HAZ.

Environmental chemicals inhalation exposure could induce pulmonary fibrosis, which is characterized by the excessive proliferation of fibroblasts and accumulation of extracellular matrix components, in which surface tension usually plays vital roles. Polyhexamethylene guanidine (PHMG) was first recognized as a potential hazard ingredient in humidifier disinfectants, which caused an outbreak of pulmonary fibrosis in South Korea. However, the underlying mechanisms involved in PHMG-induced pulmonary fibrosis have not yet been fully elucidated. Therefore, this study mainly focuses on the effect of PHMG on surface tension to unveil the influence and involved mechanisms in PHMG-induced pulmonary fibrosis. C57BL/6J mice were exposed to sub-acute PHMG aerosol for 8 weeks. The results indicated that PHMG induced pulmonary fibrosis combined with elevated surface tension. Results from in vitro study further confirmed PHMG elevated surface tension by inhibited pulmonary surfactant. Mechanistically, PHMG suppressed the key surfactant protein SP-B and SP-C by inhibiting protein expression and block their active sites. The present study, for the first time, revealed the molecular mechanism of PHMG-induced pulmonary fibrosis based on pulmonary surfactant inhibition mediated surface tension elevated. And pulmonary surfactant may be a potential target for further intervention to prevent PHMG-induced fibrosis or alleviate the symptom of relevant patients.

We integrated the high-speed synchrotron X-ray phase-contrast imaging (PCI) with a modified Kolsky compression bar loading platform to visualize the dynamic failure processes of cross-ply glass fiber reinforced composites (GFRCs). Four S-2 glass/SC-15 composite specimens were prepared, having similar thicknesses but different stacking sequences, namely as [012/9012], [9012/012], [08/908/08], and [908/08/908]. Three-dimensional synchrotron X-ray computed tomography and scanning electron microscopy (SEM) were employed to examine the microstructures and quantify the fiber volume fractions. Each specimen was notched and subjected to a dynamic three-point flexural loading. The onset of cracking close to the notch tip, crack propagation in 0° or 90° plies and their interface, crack opening, and ultimately failure of the specimen were captured by high-speed synchrotron X-ray PCI. Additional dynamic experiments were performed to determine the average time when the stress wave propagated through the specimen and correlate the X-ray images with the specimen's force-deflection response. Finally, the surface morphology of each specimen after the dynamic loading was imaged by SEM. Comparison between real-time X-ray images and post-fracture SEM images demonstrated the capability of the X-ray method to record damage evolution inside composites. Furthermore, the high spatial and temporal resolutions of the X-ray setup and edge enhancement by PCI enabled the identification of microscale damage features within 1 μs. Two damaging processes were identified, crack growth was quantified, and fracture toughness of the composites was evaluated. The method is deemed useful to reveal microscale damage mechanisms and track cracking behaviors inside cross-ply GFRCs under dynamic loading in real time.

This study aims to isolate interactions between plies and tows and reveal fundamental physics involved in transverse impact on fiber-reinforced composite (FRC) structures. Composite strips were sectioned from large panels and characterized by optical photography, three-dimensional synchrotron X-ray computed tomography, and scanning electron microscopy (SEM). Each strip was impacted perpendicularly by a right circular cylinder (RCC) projectile at a velocity ranging from ~ 150 to 600 m/s. The global strip behavior, as well as localized deformation and failure of the strip near the projectile corner, were both captured by high-speed optical imaging. S-Glass FRC strips were observed to fail in tension ahead of the RCC projectiles’ flat surfaces while Kevlar® FRC strips fractured at the projectile corners. The concept of critical velocity region previously used for impact on yarns was introduced to define different failure modes of each composite strip type. The strip damage extent was found to increase with the impact velocity and reach the maximum at the upper limit of the critical velocity region. Above the critical velocity region, the damage extent decreased with impact velocity. Wave propagations and load histories in the composite strips during impact were quantified and compared with Smith’s theory. Finally, critical velocities of single fibers, yarns, and composite strips and ballistic limits of single-ply and multi-ply composite panels were compared to provide insight into the design of impact-resistant fabrics and composites.

The materials with different moduli in tension and compression are called bi-modulus materials. Graphene is such a kind of materials with the highest strength and the thinnest thickness. In this paper, the mechanical response of the bi-modulus beam subjected to the temperature effect and placed on the Winkler foundation is studied. The differential equations about the neutral axis position and undetermined parameters of the normal strain of the bi-modulus foundation beam are established. Then, the analytical expressions of the normal stress, bending moment, and displacement of the foundation beam are derived. Simultaneously, a calculation procedure based on the finite element method (FEM) is developed to obtain the temperature stress of the bi-modulus structures. It is shown that the obtained bi-modulus solutions can recover the classical modulus solution, and the results obtained by the analytical expressions, the present FEM procedure, and the traditional FEM software are consistent, which verifies the accuracy and reliability of the present analytical model and procedure. Finally, the difference between the bi-modulus results and the classical same modulus results is discussed, and several reasonable suggestions for calculating and optimizing the certain bi-modulus member in practical engineering are presented.

Insight into ballistic impact resistance of fiber reinforced polymer composite (FRPC) strip provides detailed material damage information by isolating and investigating materials from a whole composite laminate. In this work, transverse impact experiments on single-layer S-Glass fiber/SC15 epoxy composite strips by Right Circular Cylinders (RCC) were performed. The critical velocity, essentially dividing two phenomenological phases, penetration and perforation, respectively, was obtained as 274-409 m/s after multiple shootings with different velocities. The realtime mechanical behavior of each composite strip was captured by a high-speed camera. Post-fracture images were gained by a Scanning Electronic Microscope (SEM), providing further information about failure surfaces of the fiber and matrix. Experiments show that the composite strip failed in a tent-like shape with obvious matrix failure and fiber/matrix interfacial debonding under below-critical-velocity impact. When the projectile velocity exceeded the critical velocity, materials ruptured instantly at the projectile front without wave propagating to the two ends, which indicates the loss of energy dissipation capability of the composite. An obvious transition phase, when the projectile impacted the strip in the critical velocity, was observed with part of the composite strip failing locally in transverse direction and the residual part forming a tent-like shape and being tensioned until break.

In this study, ballistic experiments were performed to determine the critical velocity of a Twaron&reg, 2040 high-performance yarn transversely impacted by round projectiles. Four different round projectiles possessing a radius of curvature of 2 &micro, m, 20 &micro, m, 200 &micro, m and 2 mm were used in this study. Load cells were mounted to the grips to measure the load history of the yarn upon impact. A high-speed camera was incorporated into the ballistic experimental setup to capture the failure process of the yarn upon impact. A scanning electron microscope was utilized to perform post-mortem failure analysis on the recovered specimens. The results showed that as the radius of curvature of the projectile increased, the critical velocity also increased. The critical velocities for all cases were bounded between those predicted from the Euler&ndash, Bernoulli beam and Smith models. Upon impact above the upper limit of the critical velocity, the axial loads revealed a demonstrative reduction. The failure surfaces changed from shear to fibrillation as the radius of curvature increased. For those specimens that failed in shear, Hertzian contact model was used to predict the critical velocity.

Oxidative stress is usually considered to be a common mechanism by which particulate matter (PM) exposure induces adverse effects. However, the further biological events such as organelle dysfunction following oxidative stress remain to be explored. In this study, we applied high-content screening (HCS) technique to investigate the toxicological effects of carbon black (CB), diesel exhaust particle (DEP) and PM2.5 on oxidative stress and organelle function in human bronchial epithelial cell (16HBE), human embryo lung fibroblast cell (HELF) and human umbilical vein endothelial cell (HUVEC) which were used to represent distinct regions of the lung, and compared the toxicity impacts of different PMs and the sensitiveness of cell lines. We found three types of PMs induced mitochondrial dysfunction in three cell lines and lysosomal alkalinization in HUVEC while only CB triggered endoplasmic reticulum (ER) stress in 16HBE and HUVEC, and oxidative stress might mediate these processes. Moreover, CB basically exhibited more potent toxicity compared with DEP and PM2.5, which might be attributed to its less oxygen content. Finally, the finding that PMs-induced toxicity impacts exhibited a cell-type dependent manner might provide some information to help to understand the sensitivity of different tissue in the lung.

Gadolinium-metallofullerenols (Gd@C82(OH)22) are a promising agent for cancer therapy and have shown beneficial effects in regulating the tumor microenvironment with low toxicity. However, the underlying mechanism by which Gd@C82(OH)22 interacts with fibroblasts remains unclear. In order to explore the critical role that activated fibroblasts play in tumorigenesis and fibrosis, we investigated the regulatory effect of Gd@C82(OH)22 in fibroblast activation and oncogenic transformation, and found that the PDGFR-α is an essential molecule in modulating the morphology and functional changes in fibroblasts after Gd@C82(OH)22 treatment. Apart from increasing the PDGFR-α protein level, Gd@C82(OH)22 nanoparticles also significantly increased the protein level of Rab5, which is required for regulating PDGFR-α endosomal recycling. The Rab5-mediated recycling of PDGFR-α maybe attributed to the Gd@C82(OH)22 regulated inhibition of fibroblast activation. Overall, our work demonstrated that Gd@C82(OH)22 nanoparticles can attenuate the PDGF-stimulated phosphorylation of PDGFR-α in fibroblasts and suppress the fibroblast activation by interrupting endosomal recycling. These findings may be contributed to the collagen accumulation for encaging cancer.

The initiation and propagation of physiological cracks in porcine cortical and cancellous bone under high rate loading were visualized using high-speed synchrotron X-ray phase-contrast imaging (PCI) to characterize their fracture behaviors under dynamic loading conditions. A modified Kolsky compression bar was used to apply dynamic three-point flexural loadings on notched specimens and images of the fracture processes were recorded using a synchronized high-speed synchrotron X-ray imaging set-up. Three-dimensional synchrotron X-ray tomography was conducted to examine the initial microstructure of the bone before high-rate experiments. The experimental results showed that the locations of fracture initiations were not significantly different between the two types of bone. However, the crack velocities in cortical bone were higher than in cancellous bone. Crack deflections at osteonal cement lines, a prime toughening mechanism in bone at low rates, were observed in the cortical bone under dynamic loading in this study. Fracture toughening mechanisms, such as uncracked ligament bridging and bridging in crack wake were also observed for the two types of bone. The results also revealed that the fracture toughness of cortical bone was higher than cancellous bone. The crack was deflected to some extent at osteon cement line in cortical bone instead of comparatively penetrating straight through the microstructures in cancellous bone. Statement of Significance Fracture toughness is with great importance to study for crack risk prediction in bone. For those cracks in bone, most of them are associated with impact events, such as sport accidents. Consequently, we visualized, in real-time, the entire processes of dynamic fractures in notched cortical bone and cancellous bone specimens using synchrotron X-ray phase contrast imaging. The onset location of crack initiation was found independent on the bone type. We also found that, although the extent was diminished, crack deflections at osteon cement lines, a major toughening mechanism in transversely orientated cortical bone at quasi-static rate, were still played a role in resisting cracking in dynamically loaded specimen. These finding help researchers to understand the dynamic fracture behaviors in bone.

The leading and trailing edges of turbine airfoils are highly susceptible to impact by foreign object debris (FOD) entrained in the gas stream of turbine engines. In this study, a narrow specimen geometry is implemented to study the FOD impact behavior of low curvature airfoil edges. Silicon carbide (SiC) ceramic specimens with and without an environmental barrier coating (EBC) are used as target materials. The EBC consists of an air plasma sprayed mullite topcoat (~166 μm) and silicon bond coat (~58 μm). Spherical (⌀ 1.5 mm) FOD simulants of silicon nitride (Si3N4), partially stabilized zirconia (PSZ), and steel are used as impactors. A modified gas gun is used to generate impact damage at normal incidence and velocities ranging between 300 to 400 m/s. In situ phase contrast X-ray radiographs, which render 2D representations of the internal transient damage, are captured during the impact experiments. Impactor hardness and toughness are found to primarily influence damage in the coating. Relative to wide specimens, the narrow specimens experience a greater level of cracking and this is postulated to result from reduced self-confinement. Irrespective of specimen geometry and impactor material type, limited cracking (i.e. enhanced shielding) is observed for the coated condition.