Low Velocity Impact Monitoring of Composite Tubes Based on FBG Sensors.

Carbon fiber reinforced composites (CFRP) are susceptible to hidden damage from low velocity external impacts during their service life. To ensure the proper monitoring of the state of the composites, it is crucial to predict the location of an impact event. In this paper, fiber Bragg grating (FBG) sensors are affixed to the surface of a carbon fiber composite tube, and an optical sensing interrogator is used to capture the central wavelength shift of the FBG sensors due to low-velocity impacts. A discrete wavelet transform is used for noise reduction in the response signals. Then, the differences in the captured response signals of the FBG sensors at different locations of the impact were analyzed. Moreover, two methods were implemented to predict the location of low-velocity impacts, according to the differences in the captured response signals. The BP neural network-based method utilized three data sets to train the neural network, resulting in an average localization error of 20.68 mm. In contrast, the method based on error outliers selected a specific data set as the reference dataset, achieving an average localization error of 13.98 mm. The comparison of the predicted results shows that the latter approach has a higher predictive accuracy and does not require a significant amount of data.

High-sensitivity micro-strain sensing using a broadband wavelength-tunable thulium-doped all-fiber structured mode-locked laser.

We demonstrate a thulium-doped mode-locked fiber laser with ultra-broadband wavelength tunability for micro-strain sensing based on the multimode interference (MMI) effect in single-mode-multimode-single-mode (SMS) fiber configuration. The homemade SMS device with high performance is fusion spliced in the laser cavity, and the developed dispersion precisely managed the all-fiber structured mode-locked picosecond laser with a record-breaking wavelength tuning range from 1976 to 1916 nm while exerting axial strain on this SMS device. We experimentally explored the regularity between the strain and the central-wavelength shift of the mode-locked pulse, and for the first time to the best of the authors' knowledge, achieved the precise in-line axial strain measurement from 0 to 5385 µÉ› by using the tunable ultrafast-laser-based sensor, and sensitivity is up to -11.5 pm/µÉ›. With high compactness and durability, this sensor has advantages in real-time dynamic measurement over other passive devices, thus will undoubtedly find various application scenarios.

Strain Sensing Behavior of 3D Printable and Wearable Conductive Polymer Composites Filled with Silane-Modified MWCNTs.

3D printing of conductive polymers is an attractive technique for achieving high flexibility, wearability, and sensing characteristics without geometrical limitations. However, there is an urgent need to integrate printability, conductivity, and sensing capability. Herein, a conductive polymer ink for 3D printing that combines the desirable features of high electrical conductivity, flexible stretchability, and strain-sensing monitoring is prepared. The ink matrix is polydimethylsiloxane and synergistically enhanced by acetylene carbon black (ACB) and multi-walled carbon nanotubes (MWCNTs) (silane or un-silane-modified). The inks are screened step-by-step to explore their printability, rheology, mechanical properties, and electrical performance upon loading. The formation of an electrically conductive network, electrical properties upon tensile load, and strain sensing stability under cyclic stretching are investigated intensively. It is demonstrated that conductive polymers filled by ACB and silane-modified, MWCNTs (MWCNTs-MTES) possess superior printability, stretchability, conductivity, and strain sensing behaviors. Finally, a flexible wearable strain-sensing skin patch is printed, and it successfully records joint motion signals on human fingers, wrists, and elbows with good stability and repeatability. Those results show the extent of potential applications in healthcare and motion monitoring fields. This work provides an efficient and simple route to achieve comfortably wearable and high-performance strain sensors.

Elastic wave propagation in hierarchical lattices with convex and concave hexagons stacked vertexes.

The paper investigates the in-plane elastic wave propagation in hierarchical lattices. The hierarchical organization is obtained by removing a certain amount of cells successively from a general hexagonal lattice that involves the re-entrant configuration with negative Poisson's ratio. The symmetry reduction caused by the alteration of the internal angle and the formed vertexes with stacking hexagons gives rise to a significant effect on the dispersion properties of the structure materials. Results show that the lattices with different hierarchy levels possess a stable behavior of the band gap in the position near the resonant frequency of the cell walls, and the gap width has an evident increase in the re-entrant hierarchical structures. In addition, band structure in the low frequency range has an unchanged performance for the varying parameters of cell walls, and the reason is owing to the steady of the structure vibration pattern for the Bloch modes. The authors' findings of the dispersion behaviors in the hierarchical lattices provide a broad design space for the lightweight materials in the wave manipulation and vibration control.

Bulk Acoustic Wave Characteristics of Pseudo Lateral-Field-Excitation on LGT Single Crystal for Liquid Phase Sensing.

In the present study, pseudo lateral-field-excitation (LFE) bulk acoustic wave characteristics on LGT crystals are investigated to increase the sensitivity of LFE devices on the liquid characteristic variations. The cut orientation of LGT crystals for pseudo-LFE is investigated and verified experimentally. For an LFE device in the pseudo-LFE mode, the thickness shear mode wave is excited by the thickness field rather than the lateral field. The present work shows that when the (yxl) 13.8° LGT plate is excited by the electric field parallel to the crystallographic axis x, it operates in the pseudo-LFE mode. Moreover, characteristics of devices including the sensitivity and impedance are investigated. The present work shows that sensitivity of LFE devices to variation of the conductivity and permittivity of the aqueous solution are 9 and 3.2 times higher than those for AT-cut quartz crystal based devices, respectively. Furthermore, it has been found that the sensitivity of the LGT LFE sensor to liquid acoustic viscosity variations is 1.4 times higher than the one for the AT-cut quartz sensor. The results are a critical basis of designing high-performance liquid phase sensors by using pseudo-LFE devices.

Identifying Genome-Wide Sequence Variations and Candidate Genes Implicated in Self-Incompatibility by Resequencing Fragaria viridis.

It is clear that the incompatibility system in Fragaria is gametophytic, however, the genetic mechanism behind this remains elusive. Eleven second-generation lines of Fragaria viridis with different compatibility were obtained by manual self-pollination, which can be displayed directly by the level of fruit-set rate. We sequenced two second-generation selfing lines with large differences in fruit-set rate: Ls-S2-53 as a self-incompatible sequencing sample, and Ls-S2-76 as a strong self-compatible sequencing sample. Fragaria vesca was used as a completely self-compatible reference sample, and the genome-wide variations were identified and subsequently annotated. The distribution of polymorphisms is similar on each chromosome between the two sequencing samples, however, the distribution regions and the number of homozygous variations are inconsistent. Expression pattern analysis showed that six candidate genes were significantly associated with self-incompatibility. Using F. vesca as a reference, we focused our attention on the gene FIP2-like (FH protein interacting protein), associated with actin cytoskeleton formation, as the resulting proteins in Ls-S2-53 and Ls-S2-76 have each lost a number of different amino acids. Suppression of FIP2-like to some extent inhibits germination of pollen grains and growth of pollen tubes by reducing F-actin of the pollen tube tips. Our results suggest that the differential distribution of homozygous variations affects F. viridis fruit-set rate and that the fully encoded FIP2-like can function normally to promote F-actin formation, while the new FIP2-like proteins with shortened amino acid sequences have influenced the (in)compatibility of two selfing lines of F. viridis.

Frequency interferences of two-unit quartz resonator arrays excited by lateral electric fields.

The coupled thickness-twist and face-shear vibrations of the lateral-field-excitation (LFE) two-unit resonator array are analyzed, and the frequency interference and shift of LFE resonator arrays are both studied. Different from most of the quartz resonator arrays based on thickness-field-excitation, the resonator array in this study operates with LFE generated by a pair of electrodes on the top surface of the resonator. By using Mindlin's first-order theory of piezoelectric plates, the electrically forced vibrations are analyzed. The effects of various structural parameters on the frequency interference and shift are examined; furthermore, the corresponding mechanisms are discussed. Varying trends of the frequency interference and shift with various structural parameters are verified by the finite element method. The results are crucial for avoiding frequency interferences between two adjacent units in parameter design of the resonator array operating on LFE.

Double-mode lateral-field-excitation bulk acoustic wave characteristics of Ca3TaGa3Si2O14 crystals.

The double-mode lateral-field-excitation (LFE) bulk acoustic wave characteristics of Ca3TaGa3Si2O14 (CTGS) crystals are investigated. It is found that LFE devices based on (yxl)-57° CTGS crystals can work on both pure-LFE and pseudo-LFE modes when the driving electric field direction is normal to the crystallographic x axis of the piezoelectric substrate. Several double-mode LFE bulk acoustic wave devices based on CTGS crystals are designed and tested. The experimental results conform to the theoretical prediction well. Being able to operate in pure-LFE and pseudo-LFE modes, the double-mode LFE sensors show high sensitivity to both mechanical and electrical property changes of analytes. The results provide the crystal cut for double-mode LFE sensors, which is a critical basis of designing high-performance chemical and biological sensors by using double-mode LFE devices.

Analysis of coupled fast-shear and extensional vibrations of a LiTaO3 crystal plate with a ferroelectric inversion layer.

The resonance vibrations of LiTaO3 fast-shear overtone mode resonators with a ferroelectric inversion layer are analyzed. In addition to the fast-shear mode, the coupled extensional mode is considered. Different from most of the LiTaO3 resonators studied in the literature that are based on the slow-shear mode, the resonator in this paper operates with the fast-shear overtone mode. Results show that the capacitance ratio assumes maxima at two resonances, which are identified to be the second overtone modes of fast-shear and extension, respectively. It is found that the thickness of the inversion layer has obvious influences on the capacitance ratio of fast-shear and extensional modes. This condition may provide a simple method to adjust capacitance ratios of piezoelectric resonators. The influence mechanisms are also discussed. Besides, the effect of the cut angle of the crystal on the mode shape of vibrations is also investigated. The results can be used as important basis of parameters designs of LiTaO3 resonators operating on the fast-shear overtone mode.

Shear horizontal waves in a multiferroic composite semiconductor structure.

Piezoelectric semiconductors (PSs) possess the physical properties of piezoelectric and semiconductor simultaneously. When a piezomagnetic (PM) material is added to the PS, the composite structures will exhibit the comprehensive mageto-electro-semiconductive (MES) coupling effects. In this paper, the propagation characteristics of shear horizontal (SH) waves in a multiferroic composite semiconductor structure are investigated, where a n-type PS thin plate is perfectly bonded to a semi-infinite PM substrate. Based on the three-dimensional macroscopic theory for PS and PM, the dispersion equations are derived analytically. Numerical examples are presented to study the effects of steady-state carrier density, cover thickness, and material properties on the phasevelocity and attenuation of SH wave systematically. The developments of various electromechanical fields through the thickness of the layers are discussed. The results show that initial electron concentration (n0) has an important effect on the distribution of most physical quantities such as displacement, stress, electric potential and electric polarization, but magnetic potential and magnetic flux density are insensitive to n0. The piezoelectric constant e15 and piezomagnetic constant f15 have different effects on the SH wave propagation and magnetic potential distribution. The theoretical results could be helpful for the analysis and design of PS-PM structures or related surface acoustic wave (SAW) devices.

Experimental and Numerical Investigation of Polymer-Based 3D-Printed Lattice Structures with Largely Tunable Mechanical Properties Based on Triply Periodic Minimal Surface.

Triply periodic minimal surfaces (TPMSs) have demonstrated significant potential in lattice structure design and have been successfully applied across multiple industrial fields. In this work, a novel lattice structure with tunable anisotropic properties is proposed based on two typical TPMS types, and their mechanical performances are studied both experimentally and numerically after being fabricated using a polymer 3D printing process. Initially, adjustments are made to the original TPMS lattice structures to obtain honeycomb lattice structures, which are found to possess significant anisotropy, by utilizing numerical homogenization methods. Based on this, a continuous self-twisting deformation is proposed to change the topology of the honeycomb lattice structures to largely tune the mechanical properties. Quasi-static compression experiments are conducted with different twisting angles, and the results indicate that self-twisting can affect the mechanical properties in specific directions of the structure, and also enhance the energy absorption capacity. Additionally, it mitigates the risk of structural collapse and failure during compression while diminishing structural anisotropy. The proposed self-twisting strategy, based on honeycomb lattice structures, has been proven valuable in advancing the investigation of lattice structures with largely tunable mechanical properties.

Three-Dimensional Thermo-Chemo-Mechanical Coupled Curing Analysis for the Filament Wound Composite Shell.

Carbon fiber resin-based composite materials are widely employed in the manufacturing of composite shells. During the curing process, the temperature gradients and cure degree gradients make it easy to generate thermal strains in both carbon fibers and resin, with the resin experiencing cure shrinkage strain due to the curing reaction, ultimately leading to residual stresses and strains. In this paper, a three-dimensional thermo-chemo-mechanical coupled curing model of the composite shell was established based on a resin test, and the changes of temperature, curing degree, residual stress, and strain during the solidification of the composite shell were investigated. First, the curing property parameters and elastic modulus of HCM-2184 resin were obtained through a curing dynamic test and a tensile test. Then, considering the heat release and shrinkage reaction of solidification, a coupled thermo-chemo-mechanical curing model was developed with the CHILE (α) elastic model, and the curing process of the composite shell was simulated numerically. The results show that the resin used in the test belongs to the autocatalytic reaction. For thin composite shells, the heat accumulation inside the shell during curing is not obvious. During the curing process, the curing shrinkage behavior of the resin is an important factor for the generation of residual stress and residual strain.

Dietary effect of Dendrobium officinale leaves on chicken meat quality, fatty acid composition, and volatile compounds profile.

Dendrobium officinale leaves (DOL) contain many active ingredients with various pharmacological effects, but are still ineffectively utilized. To investigate the feasibility of developing DOL as a feed additive, it is necessary to determine whether dietary supplementing DOL had any effect on meat quality and flavor. Our results showed that supplementation with DOL decreased the shear force while increased the pH and fat content in breast meat. Meat from DOL-fed chickens had higher levels of n-3 polyunsaturated fatty acids (PUFAs) and n-6 PUFAs, but lower n-6/n-3 ratios. Moreover, volatile compounds profile indicated that contents of aldehydes, including hexanal, pentanal, and heptanal, etc.), which were identified as the key volatile compounds in chicken meat, exhibited noteworthy rise in DOL intake groups. Octanal, 1-octen-3-ol, and 2-pentylfuran also contributed greatly to the meat overall aroma. These data provide a foundation for the comprehensive utilization of DOL as a feed additive with antibiotic substitution potential.

Multi-Scale Model for the Aging Performance of Particle-Filled Polymer Composites.

In this study, we developed a novel multi-scale model to predict the aging performance of particle-filled polymer composites (PFPCs) under thermo-oxidative aging conditions. To investigate the aging behavior, high-temperature accelerated aging tests were conducted in combination with macroscopic and microscopic characterization. At the microscopic level, the crosslinking density of the polymer matrix is calculated using the closed-loop chain reaction of polymer oxidation. In addition, the theory of polymer physics was used to determine the relationship between crosslinking density and elastic modulus. Relationships between elastic modulus and dewetting strain were analyzed at the macroscopic level. Based on the observations and analyses, a multi-scale model was developed to predict the aging performance of PFPCs. The predicted results show good agreement with the test results, which verifies the reliability of the model.

Prediction of Aging Performance of Particle-Filled Polymer Composites Based on RVE Model.

In this study, the aging performance of particle-filled polymer composites (PFPCs) under thermo-oxidative conditions was investigated on multiple scales. High-temperature-accelerated tests were conducted to analyze the effects of aging time and temperature. A representative volume element (RVE) model was established for the PFPCs using a random particle-filling algorithm. A predictive model for the crosslink density was conducted based on the closed-loop chain reaction of polymer oxidation. According to the theory of polymer physics, the relation between the crosslink density and matrix modulus was determined. The particle/matrix interface in the RVE model was represented by the cohesive zone model (CZM). The parameters of the CZM were determined by the inversion techniques. Then, a comprehensive multiscale RVE model was constructed, which was applied to predict the modulus and dewetting strain of the aged PFPCs. The predicted results show good agreement with the test results, which verifies the reliability of our model.

BAG6-A from Fragaria viridis pollen modulates gametophyte development in diploid strawberry.

Male and female gametophyte development processes are essential steps in the life cycles of all land plants. Here, we characterized a gene, FviBAG6-A, screened from the Fragaria viridis (2 n = 2x=14) pollen cDNA library and physically interacted with S-RNase. Ubiquitinated of Sa-RNase might be determined by the interaction of FviBAG6-A in the ubiquitin-proteasome system during fertilization. We found that overexpression of FviBAG6-A in Arabidopsis caused shorter silique length, and decreased silique number. Moreover, overexpression of FviBAG6-A in Fragaria vesca (2 n = 2x=14) led to a greatly reduced seed number, with nearly 80% of the seeds aborted. Analyses of paraffin sections and reactive oxygen species (ROS) content revealed that the majority of severe pollen defects were likely due to the early degradation of the tapetum and middle layer as a result of ROS accumulation and abnormal development of the uninucleate megaspore mother. Moreover, the FviBAG6-A interact with the E3 ligase SIZ1 and contribute to the SUMOylation of FviBAG6-A , which may be induced by the high level of ROS content, further promoting gametophyte abortion in strawberry transgenic lines. This study characterized the FviBAG6-A and reveals its novel function in gametophyte development.

Dietary supplementation with Dendrobium officinale leaves improves growth, antioxidant status, immune function, and gut health in broilers.

Background: The Dendrobium officinale leaves (DOL) is an underutilized by-product with a large biomass, which have been shown to exhibit immunomodulatory and antioxidant functions. The purpose of this research was to investigate the effects of DOL on broiler growth performance, antioxidant status, immune function, and gut health. Methods: One hundred and ninety-two 1-day-old chicks were selected and divided into 4 groups at random, 6 replicates for each group and 8 in each. Chicks were given a basal diet supplemented with different amounts of DOL: 0% (control group, NC), 1% (LD), 5% (MD), or 10% (HD). During the feeding trial (70 days), broiler body weight, feed intake, and residual feeding were recorded. On d 70, 12 broilers from each group were sampled for serum antioxidant and immune indexes measurement, intestinal morphological analysis, as well as 16S rRNA sequencing of cecal contents and short-chain fatty acid (SCFA) determination. Results: In comparison to the NC group, the LD group had greater final body weight and average daily gain, and a lower feed conversion ratio (p < 0.05, d 1 to 70). However, in MD group, no significant change of growth performance occurred (p > 0.05). Furthermore, DOL supplementation significantly improved the levels of serum total antioxidant capacity, glutathione peroxidase, superoxide dismutase, and catalase, but reduced the level of malondialdehyde (p < 0.05). Higher serum immunoglobulin A (IgA) content and lower cytokine interleukin-2 (IL-2) and IL-6 contents were observed in DOL-fed broilers than in control chickens (p <0.05). Compared to the NC group, duodenal villus height (VH) and villus height-to-crypt depth (VH:CD) ratio were considerably higher in three DOL supplementation groups (p < 0.05). Further, 16S rRNA sequencing analysis revealed that DOL increased the diversity and the relative abundance of cecal bacteria, particularly helpful microbes like Faecalibacterium, Lactobacillus, and Oscillospira, which improved the production of SCFA in cecal content. According to Spearman correlation analysis, the increased butyric acid and acetic acid concentrations were positively related to serum antioxidant enzyme activities (T-AOC and GSH-Px) and immunoglobulin M (IgM) level (p < 0.05). Conclusion: Overall, the current study demonstrated that supplementing the dies with DOL in appropriate doses could enhance growth performance, antioxidant capacity, and immune response, as well as gut health by promoting intestinal integrity and modulating the cecal microbiota in broilers. Our research may serve as a preliminary foundation for the future development and application of DOL as feed additive in broiler chicken diets.

Mechanical characterization of TiO2 nanowires flexible scaffold by nano-indentation/scratch.

Mechanical properties of nanowires (NWs) flexible scaffold biomaterials with open pores and channels are important factors to cell reorganize in growth for tissue regeneration engineering. However, accurate test the mechanical properties of the NWs scaffold is still a challenge because of their flexible property and porous structure. Herein, we measured the mechanical characterizes of TiO2 nanowires (TiO2NWs) flexible scaffold by multi-loads, multi-displacements mixed verification method in nano-indentation/scratch. The results showed that the hardness and Young's modulus of the TiO2NWs flexible scaffold had a certain change rules with a change of the indentation load from 5 µN to 400 µN. Meanwhile, the tangential force of the TiO2NWs flexible scaffold had significantly tensile fracture characteristic under nano-scratch. The multi-loads, multi-displacements mixed verification method by nano-indentation/scratch could be widely applied to measure the mechanical properties of all 3D NWs flexible scaffold nanostructure conveniently and accurately, which is helpful to cover the shortage of bending method for only measure the mechanical properties of 1D nanostructures.

Love wave propagation in piezoelectric structures bonded with conductive polymer films.

In this study, we investigate analytically Love wave propagation in layered piezoelectric structures, where a thin conductive polymer layer is bonded to an unbounded piezoelectric substrate. The dispersive relation is derived and the effects of viscosity and conductivity on the phase velocity and attenuation of Love wave are analyzed and discussed. The results reveal that the effects of the viscosity and conductivity on the properties of Love wave are obvious. The phase velocity is affected by the viscosity and conductivity slightly, while the attenuation is remarkably changed with the varying frequency of the waves, viscosity and conductivity, respectively. The relationship between attenuation and frequency are not monotone increasing. The analytical solutions results are well-matched with the finite element results. The results in this work is useful for the design of acoustic wave device.

Robust Impact Effect and Super-Lyophobic Reduced Galinstan on Polymers Applied for Energy Harvester.

In this paper, we present a novel reduced Galinstan-based microfluidic energy harvester, which can converse kinetic energy to electricity from an arbitrary vibration source. Firstly, the wetting behaviors of reduced Galinstan are performed, which shows a robust impact effect on polymer substrates. Moreover, the electric circuit model of the reduced Galinstan-based energy harvester is made and discussed by the use of the EDLCs (electrical double layer capacitors). After modeling, the microfluidic energy harvester with coplanar microfluidic channels is designed and fabricated. Finally, the performance of the microfluidic energy harvester is investigated, which can harvest multi-direction vibration energy. The experiment results demonstrate that the novel reduced Galinstan-based microfluidic energy harvester is suitably and uniquely applied in a complex vibration environment.