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This study aims to explore the in vitro antibacterial activity of 18 lichen species from Cangshan and the synergistic effect of their natural active products in combination with antibiotics against methicillin-resistant Staphylococcus aureus (MRSA). The in vitro antibacterial activity of 18 lichen species against 6 food-borne pathogens was determined using the agar well diffusion method, and the combined effect of active lichens and 7 common antibiotics was evaluated using the checkerboard method with MRSA as the tracer. Additionally, in vitro bactericidal curves, anti-mutagenic concentrations, and post-antibiotic effects were examined. The results demonstrated that 10 of the 18 lichen species exhibited in vitro anti-MRSA activity, with strongest antibacterial activity observed for Cetraria laevigata, showing extremely high sensitivity (the diameter of the inhibition zone was 22.0 mm). Furthermore, the combination of Lobaria kurokawae and Cladonia uncialis with piperacillin demonstrated a synergistic antibacterial effect, significantly reducing MRSA bacterial density (P

The axial-flow-induced vibration of fuel rods in the nuclear power plant is closely related to nuclear safety. In this article, a numerical study is performed on vibration of two elastic cylinders arranged side-by-side in axial flow. Large eddy simulation is employed to predict the turbulent flow. The numerical method has been verified using the experimental root-mean-square vibration amplitude of a single cylinder. A wide range of inflow velocities u∗, incident turbulence intensity Tu and space ratio P/D have been examined, where D and P are the diameter and centre-to-centre distance of the cylinders, respectively. The results show that the vibration amplitudes increase with an increasing u∗, comparable to the case of a single cylinder in axial flow. However, the two cylinders could bend outwards during a relatively high u∗ and low Tu. Although Tu significantly affects the amplitudes of the cylinders, it does not change the vibration frequency and the critical velocity at which buckling instability occurs. As the gap between the two cylinders is sufficiently small, the vibration amplitude enhances significantly due to the pronounced hydrodynamic interaction between the two elastic cylinders and surrounding fluid. The direction of buckling is no longer random but fixed.

Abstract Wounds infected with multidrug‐resistant (MDR) bacteria are increasingly threatening public health and challenging clinical treatments because of intensive bacterial colonization, excessive inflammatory responses, and superabundant oxidative stress. To overcome this malignant burden and promote wound healing, a multifunctional cryogel (HA/TA2/KR2) composed of hyaluronic acid (HA), tannic acid (TA), and KR‐12 peptides is designed. The cryogel exhibited excellent shape‐memory properties, strong absorption performance, and hemostatic capacity. In vitro experiments demonstrated that KR‐12 in the cryogel can be responsively released by stimulation with hyaluronidase produced by bacteria, reaching robust antibacterial activity against Escherichia coli (E. coli), MDR Pseudomonas aeruginosa (MDR‐PA), and methicillin‐resistant Staphylococcus aureus (MRSA) by disrupting bacterial cell membranes. Furthermore, the synergetic effect of KR‐12 and TA can efficiently scavenge ROS and decrease expression of pro‐inflammatory cytokines (tumor necrosis factor (TNF)‐α & interleukin (IL)−6), as well as modulate the macrophage phenotype toward the M2 type. In vivo animal tests indicated that the cryogel can effectively destroy bacteria in the wound and promote healing process via accelerating angiogenesis and re‐epithelialization. Proteomic analysis revealed the underlying mechanism by which the cryogel mainly reshaped the infected wound microenvironment by inhibiting the Nuclear factor kappa B (NF‐κB) signaling pathway and activating the Janus kinase‐Signal transducer and activator of transcription (JAK‐STAT6) signaling pathway. Therefore, the HA/TA2/KR2 cryogel is a promising dressing candidate for MDR bacteria‐infected wound healing.

In order to explore the antibiotics development potential of the endophytic fungus Apiospora malaysiana from Thamnolia subuliformis, the antimicrobial spectrum of Apiospora malaysiana against common pathogen was determined after comparing the effects of six commonly used methods for determination of in vitro antimicrobial activity. The effects of storage time, temperature, ultraviolet irradiation time, and pH on the stability of antimicrobial activities of Apiospora malaysiana in vitro were further investigated by using the most sensitive Staphylococcus aureus as the indicator bacterium. The results showed that there was no significant difference in the antimicrobial activity of Apiospora malaysiana in vitro by three methods (plate punching method, filter paper method, and Oxford cup method) (P>0.05). However, the results of the three fungal inhabition methods showed that the mycelial growth rate method was optimal (inhibition rate of 100%), the effect of the plate confrontation method was much lower than the former (inhibition rate of only 24.0%), and the filter paper diffusion method had no inhibiting effect. The results of in vitro antimicrobial test showed that Apiospora malaysiana had strong inhibiting effects on a variety of Gram-positive bacteria and pathogenic fungi, among which Staphylococcus aureus was the most sensitive (the diameter of the inhibition zone was 18.3 mm, highly sensitive). In addition, Apiospora malaysiana also had strong antimicrobial activity against pathogenic fungi such as drug-resistant Candida albicans (highly sensitive), Botrytis cinerea, and Rhizoctonia solani (inhibition rate of 100%). The results of the antimicrobial stability test showed that different storage time, temperature, and ultraviolet irradiation time had no significant effects on the in vitro antimicrobial activity of Apiospora malaysiana (P>0.05), but pH had a great effect on its in vitro antimicrobial activity (P

Objective: The epidemiological information associated with seizure-related burn injuries is lacking in China. Therefore, this study aims to analyze the clinical profile, management, outcome, and risk factors of burns that are directly caused by seizures among epileptic patients, and identify the epidemiological characteristics to develop effective preventive strategies. Methods: This study was conducted between January 2002 and December 2022 in a large Chinese burn center. Data including clinical profile, wound treatment, and outcome were analyzed. A multiple linear regression was used to screen the risk factors for the length of hospital stay (LOS), and a multiple logistic regression was used to screen the contributory factors for the amputation. Results: A total of 184 burn patients (55.98 % females) were enrolled, with a 0.78 % incidence rate during the study period. The mean age of the patients was 36.16 years (SD: 17.93). Patients aged 20–29 were the most affected age groups (23.37 %). Most burns were caused by flame, accounting for 60.33 % (111/184) of all cases. In total, 76.09 % of the 184 patients underwent at least one operation, and 35 patients (19.02 %) still required amputation during the study period. Burn sites (hands) had the greatest impact on amputation (OR = 3.799), followed by flame burns (OR = 3.723). The mean LOS/TBSA was 6.90 ± 8.53 d, and a larger TBSA, full-thickness burns, and a higher number of operations were identified as the risk factors for a longer LOS. There was one death among the 184 patients, with a mortality rate of 0.54 %. Conclusion: This study demonstrates that burn injuries are extremely harmful to individuals with epilepsy in China because they are at high risk of amputation and disability. Effective healthcare education and preventive programs that focus on lifestyle modifications and seizure control should be implemented to reduce the burn incidence in these populations.

Welding is one of the important connection methods for zirconium alloy, and the shear failure under the dynamic load is a typical failure mode of the weld. Aiming at clarifying the shear failure of zirconium alloy welds, three kinds of double-notched shear weld specimens with welding sizes of 2, 4, and 6 mm were designed, respectively; the shear performance of specimens under quasi-static and dynamic loading was tested by tensile testing machine and split Hopkinson pressure bar (SHPB). The stress–strain curves and shear strength were determined for the weld under quasi-static and dynamic loading. It was demonstrated that 1) an obvious strain rate strengthening effect was observed for the shear strength performance of zirconium alloy weld; 2) the shear performance of zirconium alloy weld was not sensitive to its length, but the tolerance to micro defects in the weld was improved with the increase of the weld length, which gave rise to a small increment of shear strength; 3) the failure mode of zirconium alloy welds under quasi-static loading was the typical lamellar tearing failure, and the angle between the fracture and base metal was about 17°; however, the shear failure mode showed obvious brittle characteristics under dynamic loading and the angle between fracture and base metal was almost parallel to the loading direction.

Pickering emulsions stabilized by food-grade colloidal particles have attracted increasing attention in recent years due to their “surfactant-free” nature. In this study, the alkali-treated zein (AZ) was prepared via restricted alkali deamidation and then combined with sodium alginate (SA) in different ratios to obtain AZ/SA composite particles (ZS), which were used to stabilize Pickering emulsion. The degree of deamidation (DD) and degree of hydrolysis (DH) of AZ were 12.74% and 6.58% respectively, indicating the deamidation occurred mainly in glutamine on the side chain of the protein. After the treatment with alkali, AZ particle size decreased significantly. Moreover, the particle size of ZS with different ratios was all less than 80 nm. when the AZ/SA ratio was 2:1(Z2S1) and 3:1(Z3S1), the three-phase contact angle (θo/w) were close to 90°, which was favorable for stabilizing the Pickering emulsion. Furthermore, at a high oil phase fraction (75%), Z3S1-stabilized Pickering emulsions showed the best long-term storage stability within 60 days. Confocal laser scanning microscope (CLSM) observations showed that the water-oil interface was wrapped by a dense layer of Z3S1 particles with non-agglomeration between independent oil droplets. At constant particle concentration, the apparent viscosity of the Pickering emulsions stabilized by Z3S1 gradually decreased with increasing oil phase fraction, and the oil-droplet size and the Turbiscan stability index (TSI) also gradually decreased, exhibiting solid-like behavior. This study provides new ideas for the fabrication of food-grade Pickering emulsions and will extend the future applications of zein-based Pickering emulsions as bioactive ingredient delivery systems.

Natural polysaccharides with high viscosity, good thermal stability, and biocompatibility can improve the mechanical properties of inorganic silica aerogels and enhance their application safety. However, the effects of the preparation methods of polysaccharide-silica aerogels on their microstructure and application properties have not been systematically studied. To better investigate the effect of the microstructure on the properties of aerogel materials, two aerogels with different structures were prepared using Konjac glucomannan (KGM) and tetraethoxysilane (TEOS) via physical blending (KTB) and co-precursor methods (KTC), respectively. The structural differences between the KTB and KTC aerogels were characterized, and the thermal insulation and fire-retardant properties were further investigated. The compressive strength of the KTC aerogels with a cross-linked interpenetrating network (IPN) structure was three times higher than that of the KTB aerogels, while their thermal conductivity was 1/3 of that of the KTB aerogels. The maximum limiting oxygen index (LOI) of the KTC aerogels was 1.4 times, the low peak heat release rate (PHRR) was reduced by 61.45%, and the lowest total heat release (THR) was reduced by 41.35% compared with the KTB aerogels. The results showed that the KTC aerogels with the IPN have better mechanical properties, thermal insulation, and fire-retardant properties than the simple physically blending KTB aerogels. This may be due to the stronger hydrogen-bonding interactions between KGM and silica molecules in the KTC aerogels under the unique forcing effect of the IPN, thus enhancing their structural stability and achieving complementary properties. This work will provide new ideas for the microstructure design of aerogels and the research of new thermal insulation and fire-retardant aerogels.

Control rod drop is one of the key measures for the safe shutdown of the reactor. The two important evaluation indicators of the drop process are the drop time-length and the maximum impact force. By theoretical and experimental methods, this paper analyzes the influencing factors and evaluates the performance of a new type of spider hydraulic buffer with compact structure and ingenious design, which couples mechanical force and fluid resistance. First, through experiments, it is found that the real-time curve of the maximum impact force often has a bimodal structure. And the double peaks vary with the change of the internal structure of the hydraulic buffer. Secondly, since there are many variables about the structure (aperture, position, quantity, piston stroke et al.), in order to consider their influence on the maximum impact force, an equivalent ongoing flow area of the drain holes is introduced. It suggested that when the flow area of the working holes which can be covered by the stroke is close to the flow area of the remaining holes, the impact force tends to appear a minimum value. A relationship between the maximum impact force and the structure is proposed accordingly. Finally, this paper proposes a quantitative evaluation method for comprehensive buffering performance, in which the comprehensive performance evaluation factor η (0

With the continuous improvement of nuclear reactor power, the use of surface microstructures to enhance the heat exchange between the coolant and the solid surface has become the research focus of many researchers. However, the extreme environment inside the core, especially the continuous impact of the high-velocity liquid on the solid surface, poses a severe challenge to the reliable service of the microstructure. To this end, this paper establishes a numerical calculation method for the droplet scouring the solid wall to analyze and evaluate the mechanical feasibility and reliability of the surface microstructure under the impact of high-speed droplets. First of all, the physical process of the liquid droplet scouring the solid surface was described and analyzed, then the mathematical equations which describe the physical process were built by coupling the key physical parameters of the interface such as displacement and stress. Finally, the internal stress distribution and its change trend with and without the microstructure were obtained. The calculation results show that during the process of a droplet hitting the solid surface, due to the superposition of shock waves inside the droplet, there will be a stress field distribution on the solid side that cannot be ignored. The introduction of the surface microstructure will significantly change the stress field distribution on the solid side. The liquid film formed on the surface of the microstructure has a significant buffering effect on the impact of the droplets, which greatly reduces the stress level in the solid. The maximum stress level in the solid with microstructure is only about 50% of that in the solid without the microstructure. Therefore, it can be judged that the surface microstructure can meet the mechanical performance requirements under the condition of droplet scouring.

Cubic α‐CsPbI3 has promising applications in the optoelectronic field for its excellent properties. However, α‐CsPbI3 black phase is instable at room temperature and easily converts into nonluminescent yellow orthorhombic phase (δ‐CsPbI3). Herein, the stability of α‐CsPbI3 is significantly improved by incorporating Mn2+ dopants into the perovskite lattice. Mn2+: CsPbI3 has essentially the same crystal structure as the parent α‐CsPbI3, and Mn2+ doping can promote photoluminescence quantum yield (PLQY) from 55% to 93%. Importantly, Mn2+: CsPbI3 can maintain 60% PLQY after exposing in air for 45 days, whereas the undoped CsPbI3 completely loses its luminescence in 10 days. First‐principles calculations testify that improved stability and optical properties of Mn2+: CsPbI3 are primarily attributed to the increased formation energy and tolerance factor. Accordingly, the luminance, external quantum efficiency (EQE), and T 50 lifetime of Mn2+: CsPbI3 perovskite light‐emitting diode (PeLED) reach 1066 cd m−2, 1.8%, and 2500 s, whereas the values for the undoped counterpart are only 415 cd m−2, 0.6%, and 140 s, respectively. In addition, it is evidenced that introducing a LiF buffer layer between hole transport layer and perovskite emissive layer can further boost the device performance, particularly, the luminance and T 50 lifetime achieve 1394 cd m−2 and 225 min at 140 cd m−2.

Accurate measurement of the material parameters of composite in a nondestructive manner is of great significance for evaluating mechanical performance. This study proposes to use a genetic algorithm (GA) to reconstruct the stiffness matrix of carbon fiber reinforced polymer (CFRP) with array-guided wave (GW)-based GA. By comparing the numerically calculated GW dispersion curves with the experimental wave number-frequency contour calculated with a two-dimensional Fourier transform (2D-FFT), the matching coefficient is directly obtained as the objective function of the GA, avoiding the overhead of sorting out the respective GW modes. Then the measured stiffness matrix with tensile testing and the longitudinal wave in the unidirectional CFRP is compared with the reconstructed parameters from unidirectional, cross-ply, and quasi-isotropic CFRPs with the GA. For the four independent parameters, excluding C12, an average value of 11.62% for the maximum deviation is achieved among the CFRPs with three stacking sequences, and an average deviation of 11.03% in unidirectional CFRPs is achieved for the parameters measured with different methods. A further correction of fiber orientation results in a relative deviation of only 2.72% for the elastic modulus along the tensile direction, and an expansion of the GW frequency range for the GA narrows down the relative deviation of C12 to 3.9%. The proposed GW-based GA opens up a way of in situ and nondestructive measurement for the composite stiffness matrix.

Abstract Background Developing an ideal wound dressing that meets the multiple demands of good biocompatibility, an appropriate porous structure, superior mechanical property and excellent antibacterial activity against drug-resistant bacteria is highly desirable for clinical wound care. Biocompatible thermoplastic polyurethane (TPU) membranes are promising candidates as a scaffold; however, their lack of a suitable porous structure and antibacterial activity has limited their application. Antibiotics are generally used for preventing bacterial infections, but the global emergence of drug-resistant bacteria continues to cause social concerns. Results Consequently, we prepared a flexible dressing based on a TPU membrane with a specific porous structure and then modified it with a biomimetic polydopamine coating to prepare in situ a nano-silver (NS)-based composite via a facile and eco-friendly approach. SEM images showed that the TPU/NS membranes were characterized by an ideal porous structure (pore size: ~ 85 μm, porosity: ~ 65%) that was decorated with nano-silver particles. ATR-FITR and XRD spectroscopy further confirmed the stepwise deposition of polydopamine and nano-silver. Water contact angle measurement indicated improved surface hydrophilicity after coating with polydopamine. Tensile testing demonstrated that the TPU/NS membranes had an acceptable mechanical strength and excellent flexibility. Subsequently, bacterial suspension assay, plate counting methods and Live/Dead staining assays demonstrated that the optimized TPU/NS2.5 membranes possessed excellent antibacterial activity against P. aeruginosa, E. coli, S. aureus and MRSA bacteria, while CCK8 testing, SEM observations and cell apoptosis assays demonstrated that they had no measurable cytotoxicity toward mammalian cells. Moreover, a steady and safe silver-releasing profile recorded by ICP-MS confirmed these results. Finally, by using a bacteria-infected (MRSA or P. aeruginosa) murine wound model, we found that TPU/NS2.5 membranes could prevent in vivo bacterial infections and promote wound healing via accelerating the re-epithelialization process, and these membranes had no obvious toxicity toward normal tissues. Conclusion Based on these results, the TPU/NS2.5 nanocomposite has great potential for the management of wounds, particularly for wounds caused by drug-resistant bacteria.

Ongoing climate change in recent decades exacerbated the decline in agricultural water use, and seawater irrigation could feasibly alleviate the shortage of water resources, which restricts viticulture in some countries. However, studies on the effects of seawater irrigation on grape volatiles are limited. Herein, ‘Reliance’ grapevines were irrigated with diluted seawater (10% concentrations) in the field since the pea-size berry stage (S1), stage EL 32 (S2), and the pre-veraison period (S3) every seven days. Results showed irrigation with seawater significantly increased the sugar content and decreased the organic acids when compared with the control berries. Seawater irrigation did not induce secondary soil salinization, and it enhanced the volatiles in the fatty acid and isoprene pathways without affecting the amino acid pathway aroma. More terpenes were found in seawater-treated berries, including citronellol, β-myrcene, α-terpineol, and trans-rose oxide. Gene profiling by RT-qPCR analysis revealed that VvLOXA could be the primary gene in C6 volatile biosynthesis altered by the seawater. Moreover, seawater irrigation during the pea-size period had the best effect on fruit quality. This work adds to our understanding of the effect of seawater irrigation on grape aroma quality and provides a sufficient basis for the utilization of seawater in vineyards.

Abstract Background Bacterial infection is one of the most common complications in burn, trauma, and chronic refractory wounds and is an impediment to healing. The frequent occurrence of antimicrobial-resistant bacteria due to irrational application of antibiotics increases treatment cost and mortality. Graphene oxide (GO) has been generally reported to possess high antimicrobial activity against a wide range of bacteria in vitro. In this study, a graphene oxide-quaternary ammonium salt (GO-QAS) nanocomposite was synthesized and thoroughly investigated for synergistic antibacterial activity, underlying antibacterial mechanisms and biocompatibility in vitro and in vivo. Methods The GO-QAS nanocomposite was synthesized through amidation reactions of carboxylic group end-capped QAS polymers with primary amine-decorated GO to achieve high QAS loading ratios on nanosheets. Next, we investigated the antibacterial activity and biocompatibility of GO-QAS in vitro and in vivo. Results GO-QAS exhibited synergistic antibacterial activity against bacteria through not only mechanical membrane perturbation, including wrapping, bacterial membrane insertion, and bacterial membrane perforation, but also oxidative stress induction. In addition, it was found that GO-QAS could eradicate multidrug-resistant bacteria more effectively than conventional antibiotics. The in vitro and in vivo toxicity tests indicated that GO-QAS did not exhibit obvious toxicity towards mammalian cells or organs at low concentrations. Notably, GO-QAS topically applied on infected wounds maintained highly efficient antibacterial activity and promoted infected wound healing in vivo. Conclusions The GO-QAS nanocomposite exhibits excellent synergistic antibacterial activity and good biocompatibility both in vitro and in vivo. The antibacterial mechanisms involve both mechanical membrane perturbation and oxidative stress induction. In addition, GO-QAS accelerated the healing process of infected wounds by promoting re-epithelialization and granulation tissue formation. Overall, the results indicated that the GO-QAS nanocomposite could be applied as a promising antimicrobial agent for infected wound management and antibacterial wound dressing synthesis.

Abstract Background Silver and photothermal therapy (PTT) have been widely used for eradicating the drug-resistant bacteria. However, the risks of excess of silver for humans and the low efficiency of PTT still limit their in vivo therapeutic application. Integration of two distinctive bactericides into one entity is a promising platform to improve the efficiency of antimicrobial agents. Results In this study, a chemo-photothermal therapeutic platform based on polydopamine (PDA)-coated gold nanorods (GNRs) was developed. The PDA coating acquired high Ag+ ions loading efficiency and Cy5-SE fluorescent agent labeled glycol chitosan (GCS) conjugation (Ag+-GCS-PDA@GNRs). This platform became positively charged in the low pH environment of the abscess, allowing their accumulation in local infection site as revealed by thermal/florescence imaging. The loaded Ag+ ions was released in a pH-sensitive manner, resulting in selective Ag+ ions delivery to the abscess environment (pH ~ 6.3). More importantly, the ultralow dose of Ag+ ions could effectively damage the bacterial membrane, causing the permeability increase and the heat resistance reduction of the cell membrane, leading to the large improvement on bactericidal efficiency of PTT. On the other hand, the hyperthermia could trigger more Ag+ ions release, resulting in further improvement on bactericidal efficiency of chemotherapy. Combinational chemo-hyperthermia therapy of Ag+-GCS-PDA@GNRs could thoroughly ablate abscess and accelerate wound healing via a synergistic antibacterial effect. Conclusions Our studies demonstrate that Ag+-GCS-PDA@GNRs is a robust and practical platform for use in chemo-thermal focal infection therapy with outstanding synergistic bacteria ablating.

Abstract An ideal wound dressing can both promote wound healing and prevent bacterial infection. Here, we report a potential dressing prepared by incorporating an optimized concentration of silver nanoparticles (AgNPs) into the microfibers of a natural eggshell membrane (EM) using environmentally friendly and mussel-inspired dopamine. Briefly, acid-treated EM was used as a porous membrane for polydopamine-reduced AgNPs synthesis. To obtain the optimal cytocompatible silver concentration, cellular attachment and MTT assay were performed with different concentrations of AgNPs. The morphology of the EM and AgNPs was confirmed by scanning electronic microscopy, scanning transmission electronic microscopy and Fourier transform infrared spectroscopy. The synthesized EM/AgNPs exhibited steady and safe AgNPs release, which was further tested for antibacterial activity against Escherichia coli and Staphylococcus aureus by disc diffusion method and bacterial suspension assay. Finally, in a murine full-thickness skin wound model, we found that EM/AgNPs could promote re-epithelialization, granulation tissue formation and wound healing via enhancing cell proliferation, as demonstrated by the expression of proliferating cell nuclear antigen (PCNA), and controlling inflammation response, as demonstrated by the expression of interleukin-1β (IL-1β). These findings suggest that EM/AgNPs may have a promising application in wound management.

A hydroponic co-culture system was adopted to determine the allelopathic potential of garlic on the growth of pepper plants. Different numbers of garlic plants (0, 2, 4, 8 and 12) were hydroponically co-cultured with two pepper plants to investigate allelopathic effects on the growth attributes and antioxidative defense system of the test pepper plants. The responses of the pepper plants depended on the number of garlic plants included in the co-culture system, indicating an association of pepper growth with the garlic root exudate concentration. When grown at a pepper/garlic ratio of 1:1 or 1:2, the pepper plant height, chlorophyll content, and peroxidase (POD), catalase (CAT) and phenylalanine ammonia-lyase (PAL) activities were significantly increased after 30 days of co-culture; in contrast, reduction in methane dicarboxylic aldehyde (MDA) content was observed. However, when the pepper/garlic ratio was 1:4 or higher, these morphological indices and protective enzyme activities were significantly inhibited, whereas MDA levels in the pepper leaves were significantly increased due to severe membrane lipid peroxidation. The results indicate that although low concentrations of garlic root exudates appear to induce protective enzyme systems and promote pepper growth, high concentrations have deleterious effects. These findings suggest that further investigations should optimize the co-culture pepper/garlic ratio to reduce continuous cropping obstacles in pepper production.

Hypervelocity impact (HVI), ubiquitous in low Earth orbit with an impacting velocity in excess of 1 km/s, poses an immense threat to the safety of orbiting spacecraft. Upon penetration of the outer shielding layer of a typical two-layer shielding system, the shattered projectile, together with the jetted materials of the outer shielding material, subsequently impinge the inner shielding layer, to which pitting damage is introduced. The pitting damage includes numerous craters and cracks disorderedly scattered over a wide region. Targeting the quantitative evaluation of this sort of damage (multitudinous damage within a singular inspection region), a characterization strategy, associating linear with nonlinear features of guided ultrasonic waves, is developed. Linear-wise, changes in the signal features in the time domain (e.g., time-of-flight and energy dissipation) are extracted, for detecting gross damage whose characteristic dimensions are comparable to the wavelength of the probing wave; nonlinear-wise, changes in the signal features in the frequency domain (e.g., second harmonic generation), which are proven to be more sensitive than their linear counterparts to small-scale damage, are explored to characterize HVI-induced pitting damage scattered in the inner layer. A numerical simulation, supplemented with experimental validation, quantitatively reveals the accumulation of nonlinearity of the guided waves when the waves traverse the pitting damage, based on which linear and nonlinear damage indices are proposed. A path-based rapid imaging algorithm, in conjunction with the use of the developed linear and nonlinear indices, is developed, whereby the HVI-induced pitting damage is characterized in images in terms of the probability of occurrence.

Wireless sensor networks are increasingly adopted both in aircraft and civil structural health monitoring. However, due to the limited resources on a wireless sensor node, structural evaluation ability of the wireless sensor network is also limited, especially for large-scale structures. This paper presents a multi-agent cooperation system based on mobile agent technology for wireless sensor network-based structural health monitoring which deals with the evaluation of large-scale structure. Mobile agent with the signal processing or evaluation algorithm is designed to migrate among different sensor nodes and perform network self-organization, data processing, information fusion, and damage estimation. This method can reduce the request to the sensor nodes and achieve a better monitoring and evaluation performance through multiagent cooperation. The proposed mobile multiagent system is evaluated by a large dimension aerospace aluminum structure monitoring experiment in which strain distribution and joint failure are monitored by different sensors. Experimental results show that the system can significantly improve the monitoring performance for large-scale structures.

The application of gas diffusion electrodes (GDEs) for the electrochemical reduction of CO2 to value-added products creates the possibility of achieving current densities of a few hundred mA cm-2. To achieve stable operation at such high reaction rates remains, however, a challenging task, due to the flooding of the GDE. In order to mitigate flooding in a zero-gap membrane-electrode assembly (MEA) configuration, paths for effective electrolyte perspiration inside the GDE structure have to be kept open during the electrolysis process. Here we demonstrate that apart from the operational parameters of the electrolysis and the structural properties of the supporting gas diffusion layers, also the chemical composition of the applied catalyst inks can play a decisive role in the electrolyte management of GDEs used for CO2 electroreduction. In particular, the presence of excess amounts of polymeric capping agents (used to stabilize the catalyst nanoparticles) can lead to a blockage of micropores, which hinders perspiration and initiates the flooding of the microporous layer. Here we use a novel ICP-MS analysis-based approach to quantitatively monitor the amount of perspired electrolyte that exits a GDE-based CO2 electrolyser, and we show a direct correlation between the break-down of effective perspiration and the appearance of flooding--the latter ultimately leading to a loss of electrolyser stability. We recommend the use of an ultracentrifugation-based approach by which catalyst inks containing no excess amount of polymeric capping agents can be formulated. Using these inks, the stability of electrolyses can be ensured for much longer times. [ABSTRACT FROM AUTHOR]