Loss Factor Research Articles

Curing monitoring of adhesive layers between metal adherends by ultrasonic resonance technique

Abstract Layer resonance induced by ultrasonic wave incidence is applied to monitor the viscoelastic properties of a curing adhesive layer between metal plates. The theoretical analysis shows that when the adhesive layer is modeled as a linear viscoelastic material, the ultrasonic reflection spectrum takes local minima at the layer resonance frequencies depending on the wave velocity of the adhesive. On the other hand, the local minima of the reflection spectrum can be expressed as a function of the loss factor of the adhesive. Based on these results, a characterization technique for the wave velocity and the loss factor of a curing adhesive layer is proposed. This technique enables the evaluation of the viscoelastic properties even if the reflected waves from both faces of a bond layer cannot be separated. The proposed method is employed to investigate the curing behavior of bi-component epoxy adhesives. As a result, it is shown that the bonding condition affects the variation of the wave velocity and loss factor. The estimated wave velocity increases as the curing proceeds, while the loss factor sometimes takes a local maximum depending on the bonding condition and the frequency range. When the mixing ratio of the main and curing agents is imbalanced, the variation of the wave velocity becomes gradual. Furthermore, the increase in the curing temperature leads to fast changes in the wave velocity and loss factor. The proposed technique has the potential to provide insight into the curing behavior of the adhesive layer by incorporating it into other measurement methods and theories.

Factors of Weight Loss for Telemedically Supported Metabolic Syndrome Patients in a Controlled Trial

Metabolic syndrome (MetS) is a complex of interrelated risk factors, associated with several serious chronic diseases like diabetes. The goal of this study was to find dietary factors of successful weight loss for MetS outpatients. We performed a 90-day dietary intervention in a telemedically supported, pre- and post-test, controlled trial in Hungary involving 132 MetS patients; 67 were in the intervention, and 65 were in the control group. Patients in the intervention group used wireless smart devices, a dietary logger, and a lifestyle app. During the trial, we recorded the patients’ weight loss and diet composition. For analysis, t-tests were used, and the temporal trends of diet composition in the intervention group were analyzed between two sub-groups according to weight loss success. Correlation and regression models were used to find predictors of success. The intervention group achieved more weight loss, and the success in this group was linked with more consumption of raw fruits/vegetables, poultry and potato dishes, while age had a negative effect. We conclude that telemedically supported dietary coaching is an efficient alternative for interventions directed at weight loss. Future trials should investigate the therapeutic application of diets rich in raw fruits, especially apples, and vegetables, as well as poultry dishes.

Luminescent Anthracene-based Elastic Mixed Molecular Crystals for Flexible and FRET-Assisted Optical Waveguides

Abstract Optical waveguides based on elastic molecular crystals are of interest as flexible and compact optical communication materials. Low emission efficiency is often a problem in terms of communication signal strength, and an increase in the loss factor α due to fluorescence reabsorption in the crystal reduces the photon transport efficiency. Here, we report the development and improvement of Förster resonance energy transfer (FRET)-assisted optical waveguides using anthracene-based elastic mixed molecular crystals. 9,10-Dicyanoanthracene was selected as the dopant for solution-grown crystallization of 9,10-dibromoanthracene. 1H NMR measurements of the obtained crystals showed that the acceptor doping to be 1%-5%. Elastic behavior was observed even when doped with a few percent of the acceptor. The quantum efficiency was 0.016, a dramatic improvement over the previous luminescent EMMC (0.004). The α value (92 dB/cm) of this crystal containing 1%-doped 9,10-dicyanoanthracene is much lower than that of the crystal consisting of only 9,10-dibromoanthracene (1258 dB/cm) due to the reduced reabsorption in the FRET system. We have demonstrated a practical approach towards developing improved fluorescent, highly efficient, and flexible optical waveguides by constructing the mixed crystal structure by selecting appropriate acceptor molecules and their low doping ratios.

Multi-scenario refractive index sensor based on merging BIC in an all-dielectric metasurface

In recent years, bound states in the continuum (BICs) in the all-dielectric metasurfaces have attracted considerable attention due to the low radiation loss and large quality factor (Q-factor). In this study, we design a highly sensitive refractive index sensor working in multi-scenario based on merging quasi-BIC in the silicon nitride metasurface. By adjusting the thickness of the metasurface and keeping the structural symmetry, nine BICs distributed in momentum space form the merging BIC at the Γ point with significantly enhanced Q-factor. The transmission spectra of the metasurface sensor disperse with the refractive index in multi-scenario. The modulation depth of the Fano resonance spectrum can exceed 99.9%. The sensitivity and figure of merit of the refractive index sensor based on the merging quasi-BIC can reach 41.35 nm/RIU and 13,389.1 RIU-1 for gas, 59.05 nm/RIU and 8,415.9 RIU-1 for blood, and 66.08 nm/RIU and 8,845.8 RIU-1 for cerebrospinal fluid, respectively. Furthermore, we investigate the influence of the structural deviations on the Q-factor, which of the merging quasi-BIC maintains higher than that of the isolated quasi-BIC. Our work offers a method for designing high-sensitivity sensors working in multi-scenarios, which may hold significant potential for enhancing device performance in gas and biological detection.

Mechanical properties of basalt/jute fiber composites to improve the phenomenon of drawing delamination

AbstractIn recent years, natural fibers have been commonly used to reinforce various polymers, resulting in composites with excellent mechanical properties. To address the challenge of delamination and significant fiber pull‐out in inter‐laminar hybrid composites during stretching, this study focused on preparing intra‐laminar hybrid textile composites using basalt fibers (BFs) and jute fibers (JFs) as raw materials. Moreover, the mechanical properties of BF/JF intra‐layer blended fabric composites were investigated. The prepared composites underwent tensile, flexural, impact, and dynamic mechanical analysis (DMA). The results indicated that intra‐laminar blended composites demonstrated superior mechanical properties compared to inter‐laminar blended fabric composites. The DMA results revealed that the intra‐laminar blended composites featured a high peak loss factor. Morphological analysis indicated enhanced stress transfer from fiber‐to‐fiber and fiber‐to‐matrix in the intra‐laminar blended composites.Highlights Fiber blending can expand the application areas of natural fibers. Fiber blending can reduce interlayer damage. Intra‐layer blending differs from interlayer hybrid composites. Strong bonding between fibers facilitates effective stress transfer. “Green” composites exhibit exceptional mechanical properties.

Experimental Investigation of Tensile, Shear, and Compression Behavior of Additional Plate Damping Structures with Entangled Metallic Wire Material

To fulfill the vibration damping requirements of plate structures under complex conditions, additional damping structures with entangled metallic wire material (EMWM) are proposed based on the excellent physical properties of EMWM. A batch of specimens with different filament diameters, densities, and thicknesses are prepared. The stiffness and loss factors are taken as the evaluation indexes, and orthogonal tests are conducted to obtain the tensile, shear, and compression properties. The results show that the optimal parameter combinations can be obtained through orthogonal tests. For the specimens with optimal parameter combinations, the mechanical tests under different loading rates and loading displacements are carried out. With the increase in loading rate, the tensile and shear forces appear to display fracture failure in advance, and the compression performance is stable without significant changes. The change rule under each mechanical test is explored using the stiffness and loss factor evaluation index. It provides a reference for the analysis of the preparation parameters of subsequent additional damping structures with EMWM.

Fasting in Judo—Between Healthy Weight Control and Health Hazard: A Narrative Review

Rapid weight loss strategies and weight cycling (losing and gaining weight repeatedly) are acknowledged problems in sports with weight categories, including judo. Extreme fasting, especially if combined with dehydration and intense physical exercise, may harm health and development, particularly those of children and teenagers engaging in judo competitions. However, there is substantial evidence for positive health effects of other forms of fasting. Here, we aim to provide an updated overview of the potential health risks associated with extreme dietary strategies in judo and contrast them with health-promoting fasting approaches. We conclude that the literature on the long-term health consequences of fasting in judo is scarce. This applies specifically to its potential association with eating disorders. Although many reports have highlighted the short-term risks of rapid weight loss, vulnerability and protection factors remain poorly understood. Rigorous scientific studies are needed to disentangle the factors that render fasting in judo healthy or unhealthy, considering both physical and mental health. We argue that a better understanding of weight management in judo is crucial to preventing health risks and designing healthy weight loss strategies, especially for young athletes.

Hypothesis testing for detecting outlier evaluators.

In epidemiological studies, the measurements of disease outcomes are carried out by different evaluators. In this paper, we propose a two-stage procedure for detecting outlier evaluators. In the first stage, a regression model is fitted to obtain the evaluators' effects. Outlier evaluators have different effects than normal evaluators. In the second stage, stepwise hypothesis tests are performed to detect outlier evaluators. The true positive rate and true negative rate of the proposed procedure are assessed in a simulation study. We apply the proposed method to detect potential outlier audiologists among the audiologists who measured hearing threshold levels of the participants in the Audiology Assessment Arm of the Conservation of Hearing Study, which is an epidemiological study for examining risk factors of hearing loss.

Genetic background of high myopia in children.

High myopia is a significant risk factor for irreversible vision loss and can occur in isolation or as a component of various syndromes. However, the genetic basis of early-onset high myopia remains poorly understood. We aimed to identify the causative genetic variants for high myopia in a cohort of Slovenian children. The study included children referred to a tertiary paediatric ophthalmology centre at the University Eye Clinic in Ljubljana between 2010 and 2022. The participants met the following inclusion criteria: age ≤ 15 years and high myopia ≤-5.0 D before the age of 10 years. Genetic analysis included exome sequencing and/or molecular karyotyping. Participants were categorized based on clinical presentation: high myopia with systemic involvement, high myopia with ocular involvement, and isolated high myopia. Genetic analysis of 36 probands revealed a genetic cause of high myopia in 22 (61.1%) children. Among those with systemic involvement (50.0%), genetic causes were identified in 13 out of 18 children, with Stickler's and Pitt-Hopkins being the most common syndromes. Among cases of high myopia with ocular involvement (38.9%), a genetic cause was found in 8 out of 14 probands, including (likely) pathogenic variants in genes related to retinal dystrophies (CACNA1F, RPGR, RP2, NDP). The non-syndromic ARR3- associated high myopia was identified in the isolated high myopia group. A genetic cause of high myopia was identified in 61.1% of children tested, demonstrating the value of genetic testing in this population for diagnosis and proactive counseling.

Effect of epoxidation level on rheological properties of epoxidized natural rubber-based magnetorheological elastomer

Epoxidized natural rubbers (ENR)are potential to be an alternative of natural rubber as matrix of magnetorheological elastomers (MREs). These ENR-based MREs offer various advantages such as excellent mechanical properties and damping characteristics that are well-suited for applications in vibration control and noise reduction devices. However, there is a paucity information in regard to the effect of different epoxidation levels on rheological properties of MRE. Therefore, the main aim of this study is to explore the influence of epoxidation level on rheological properties of MRE using commercialized ENR corresponding to ENR 25 and ENR 50. ENR-based MREs were created by blending with carbonyl iron particles (CIPs) and other additives, followed by curing at 150 °C for 30 min. The study involved producing ten MRE samples with various weight percentages of CIP (0,10,30,50 and 70 wt%). The storage modulus of ENR 50 exhibited a significant increment from 0.73 MPa to 1.04 MPa as compared to ENR 25 which caused the storage modulus to increase from 0.77 to 0.88 MPa. This showed that ENR 50-based MRE are stiffer in comparison to ENR 25-based MRE. Initial loss modulus value for ENR 50 (0.098 MPa) was lower than that of ENR 25 (0.112 MPa), consequently less energy is dissipated to surrounding for ENR 50-based MRE compare ENR 25-based MRE. The loss factor that represents damping properties showed that ENR 50 reached higher values (0.120 MPa) compared to ENR 25 (0.106 MPa). The increasing of CIPs content from 0 to 70 wt% contributed to increasing of magnetorheological effect for both ENR-based MRE where ENR 25 produced slightly higher with increment of 1.88 % to 22.6 % than ENR 50-based MRE with increment of 2.47 % to 18.18 % due to rise of magnetic forces generated from interaction of magnetic moments in magnetic domains of each CIPs. The results and analysis indicate that different levels of epoxidation in ENR have a marginal impact on the rheological properties of ENR-based MREs.

Network and systems biology approaches help investigate gene regulatory interactions between Salmonella disease and host in chickens: Model-based in silico evidence combined with gene expression assays.

Salmonella enteritidis (SE), a previously widespread infectious disease, is still cited as a major factor in economic losses in commercial chicken production. The host's genetic immune system determines the pathogenicity of a particular bacterium. To shed light on this topic, it was necessary to understand the key candidate genes essential for regulating susceptibility and resistance to the target disease. The field of poultry farming in particular has benefited greatly from the connection between quantitative and molecular genetics. This study aims to identify the most important immune-related genes and their signalling pathways (gene ontology, co-expression and interactions) and to analyse their accumulation in host-resistant SE diseases by combining gene expression assays with model-based in silico evidence. A two-step experimental design is followed. To start, we used free computational tools and online bioinformatics resources, including predicting gene function using a multiple association network integration algorithm (geneMania), the Kyoto Encyclopedia of Genes and Genomes, the Annotation, Visualization and Integrated Discovery (DAVID) database and the stimulator of interferon genes. Natural resistance-associated macrophage protein 1 (NRAMP1), Toll-like receptor 4 (TLR4), interferon-γ (IFNγ), immunoglobulin Y (IgY) and interleukin 8 (IL8) were among the five genes whose expression levels in liver, spleen, and cecum were evaluated at 1107 SE after 48h of inoculation. This molecular study was developed in the second phase of research to validate the in silico observations. Next, we use five promising biomarkers for relative real-time polymerase chain reaction (PCR) quantification: TLR4, IL8, NRAMP1, IFNγ and IgY genes in two case and control assays. The 2-∆∆Ct Livak and Schmittgen method was used to compare the expression of genes in treated and untreated samples. This method normalizes the expression of the target gene to that of actin, an internal control and estimates the change in expression relative to the untreated control. Internal control was provided by the Beta actin gene. Next, statistically, the postdoc test was used for the evaluation of treatments using SAS version 9.4, and p values of 0.05 and 0.01 were chosen for significant level. Interestingly, the results of our study suggest the involvement of various factors in the host immune response to Salmonella. These include inducible nitric oxide synthase, NRAMP1, immunoglobulin light chain (IgL), transforming growth factor B family (TGFb2, TGFb3 and TGFb4), interleukin 2 (IL2), apoptosis inhibitor protein 1 (IAP1), TLR4, myeloid differentiation protein 2 (MD2), IFNγ, caspase 1 (CASP1), lipopolysaccharide-induced tumour necrosis factor (LITAF), cluster of differentiation 28 (CD28) and prosaposin (PSAP). The summary of gene ontology and related genes found for SE resistance was surprisingly comprehensive and covered the following topics: positive regulation of endopeptidase activity, interleukin-8 production, chemokine production, interferon-gamma production, interleukin-6 production, positive regulation of mononuclear cell proliferation and response to interferon-gamma. The role of these promising biomarkers in our networks against SE susceptibility is essentially confirmed by these results. After 48h, the spleen showed significant expression of the tissue-specific gene expression patterns for NRAMP1 and IL8 in the cecum, spleen and liver. Based on this information, this report searches for resistance and susceptibility lineages in most genomic regions for SE. In conclusion, the development of an appropriate selection program to improve resistance to salmonellosis can be facilitated by a comprehensive understanding of the immune responses of the chicken immune system after SE exposure.

Optimizing Nitrate Fertilizer Production Using Plasma-Activated Water (PAW) Technology: An Analysis of Dielectric Properties

This study investigates the potential of Plasma-Activated Water (PAW) technology for the production of nitrate fertilizer, focusing on the dielectric properties of plasma-treated water, such as the dielectric constant and dielectric loss factor. The research aims to elucidate the impact of plasma treatment and varying water flow rates on these properties. An experimental approach was employed wherein ion-free water was subjected to plasma treatment at different flow rates (0.5, 1.0, and 2.0 L/min) and durations (1, 2, and 3 h). The results reveal a marked enhancement in the dielectric properties of the water following plasma treatment, with the most significant improvements observed at a flow rate of 0.5 L per minute and a treatment duration of 3 h, and dielectric efficiencies of 97.82%, 97.21%, and 96.61% achieved at flow rates of 0.5, 1.0, and 2.0 L/min, respectively. These findings demonstrate that PAW technology enhances the efficiency of nitrate fertilizer production by optimizing energy storage and reducing energy losses. The study underscores the potential of PAW as a sustainable, environmentally benign alternative to conventional chemical fertilizers, contributing to more efficient and sustainable agricultural practices.

Follow-Up of Neonatal Hearing Screening in the Risk Factor Group for Hearing Loss: Results from a Tertiary Medical Center

Introduction: Universal newborn hearing screening has been successfully implemented in many places around the world, and it is recommended that cases with risk factors for hearing loss be followed-up regardless of hearing screening results. However, there is a need for clarity regarding the recommended rate of follow-up and which tests should be performed. The aim of this study was to assess the audiologic follow-up program for the group with risk factors. Method: Our retrospective study involved children of various ages with a risk factor for hearing loss who passed the initial neonatal hearing test but were later diagnosed with hearing loss. Out of 113,708 children born at Hadassah University Medical Center during the years 2013–2021, 6763 were at risk of hearing loss, and their follow-up audiologic test results were studied. Results: Audiologic testing including ABR, OAE, tympanometry and behavioral audiometry was performed in 1534 of 6763 (23%) of the risk factor group that returned to the hospital. In total, 73 children (4.7%) were diagnosed with hearing loss, 54 of whom failed the initial screening and 19 who had passed it. Further examination of the children that passed the initial screening and were later diagnosed with a hearing loss revealed that four cases had been missed in screening (one familial mild hearing loss, one familial progressive loss, one premature infant with a high tone loss, and one NICU graduate with CNS involvement). Another nine cases had late-onset hearing loss (three meningitis, five CMV, and one with a mitochondrial disease). An additional six cases were diagnosed late, and the age of onset of the hearing loss was unknown (two intubated, two with hydrocephalus, one with Cerebral Palsy, and one with general developmental delay). Conclusions: These results reveal the importance of implementing a refined protocol for monitoring hearing in the high-risk group of children that pass neonatal hearing screening with respect to which hearing tests should be conducted, at what age, and the duration of follow-up. Also, barriers to follow-up must be dealt with, and parents should be more involved in the monitoring process.

Persistent Chronic Active T-Cell-Mediated Rejection After Kidney Transplantation Is Associated With Poor Allograft Survival.

Histopathological findings of chronic active T-cell-mediated rejection (CA-TCMR) have been reported to potentially improve with treatment. However, whether this improvement is associated with a better renal prognosis remains unclear. This study was performed to analyze the impact of the histological response to therapy on kidney allograft survival in patients with CA-TCMR. The data of patients diagnosed with CA-TCMR between January 2018 and May 2023 were retrospectively reviewed. A composite graft endpoint was defined as a two-fold increase in the serum creatinine level or the development of end-stage kidney disease. Thirty-seven patients with CA-TCMR underwent 46 follow-up biopsies. Eleven patients who were diagnosed with CA-TCMR at the last biopsy were classified as the persistent group, while the remaining 26 patients were classified as the transient group. Both before and after treatment, there were no significant changes in serum creatinine, estimated glomerular filtration rate, or proteinuria in either group. However, the transient group showed a significant reduction in interstitial fibrosis and tubular atrophy without a specific etiology (IFTA). This improvement was attributed to better histopathological Banff scores after treatment. Patients with persistent CA-TCMR had significantly worse graft survival than those with transient CA-TCMR (p = 0.002), even after adjusting for significant clinical factors (hazard ratio: 11.4; 95% CI: 1.1-120.0; p = 0.043). Our findings suggest that the persistence of histopathologic evidence of CA-TCMR after treatment is a significant risk factor for allograft loss compared with transient CA-TCMR.

Occupational epidemiological characteristics of noise-induced hearing loss and the impact of combined exposure to noise and dust on workers’ hearing—a retrospective study

IntroductionThe aim of the study was to investigate the occupational epidemiological characteristics of hearing loss among noise-exposed workers through a cross-sectional study and to explore the impact of combined noise and dust exposure on workers’ hearing loss through a longitudinal study.ResultsThis cross-sectional study revealed that the risk of speech-frequency hearing loss increases with age (OR = 1.096, 95%CI = 1.081–1.111). Independent factors influencing high-frequency hearing loss include sex, age, hazardous factors, industry category, and enterprise size. Scientific research and technical services (OR = 1.607, 95%CI = 1.111–2.324), wholesale and retail (OR = 2.144, 95%CI = 1.479–3.107), manufacturing (OR = 1.907, 95%CI = 1.429–2.545), and other industries (OR = 1.583, 95%CI = 1.002–2.502) are risk factors for high-frequency hearing loss, whereas being female (OR = 0.297, 95%CI = 0.236–0.373) is a protective factor against high-frequency hearing loss. Independent factors influencing occupational noise-induced hearing loss include sex, working age, hazardous factors, industry category, smoking, and drinking, with the risk of occupational noise-induced hearing loss increasing with working age (OR = 1.045, 95%CI = 1.031–1.058). Noise and dust work (OR = 1.271, 95%CI = 1.011–1.597), other work (OR = 0.619, 95%CI = 0.479–0.800), manufacturing (OR = 2.085, 95%CI = 1.336–3.254), other industries (OR = 2.063, 95%CI = 1.060–4.012), occasional smokers (OR = 0.863, 95%CI = 0.652–1.142), regular smokers (OR = 1.216, 95% CI = 0.987–1.497), and excessive drinkers (OR = 2.171, 95%CI = 1.476–3.193) are risk factors for occupational noise-induced hearing loss, whereas being female (OR = 0.496, 95%CI = 0.347–0.709) is a protective factor against occupational noise-induced hearing loss. The longitudinal study revealed differences in pure-tone hearing threshold test results at 500 Hz, 1,000 Hz, 3,000 Hz, 4,000 Hz, and 6,000 Hz in both ears before and after enrollment among noise-exposed workers (p < 0.05). Combined noise and dust exposure (OR = 4.660, 95%CI = 1.584–13.711), 1st year (OR = 1.540, 95%CI = 1.128–2.103), 2nd year (OR = 1.994, 95%CI = 1.409–2.821), and 3rd year (OR = 1.628, 95%CI = 1.170–2.264) were risk factors for high-frequency hearing loss.DiscussionCombined noise and dust exposure is a risk factor for occupational noise-induced hearing loss. Additionally, occupational noise-induced hearing loss is influenced by gender, working age, enterprise industry category, smoking, and drinking. Employers should enhance occupational health management and improve workers’ occupational health literacy, with a particular focus on older male workers of long working age, and those with unhealthy habits. Combined exposure to noise and dust may have a synergistic effect on causing high-frequency hearing loss, and comprehensive protective measures should be implemented for workers exposed to both.

Prevalence and risk factors for skeletal muscle mass loss in individuals with type 1 diabetes

Prevalence and risk factors for skeletal muscle mass loss in individuals with type 1 diabetes

The Electrical Conductivity Mechanisms and Dielectric Properties of Multiphase Co-synthesized CuV2O6–MnV2O6

AbstractMany research studies on photodegradation, energy storage applications, and biosensing have focused on single and mixed Cu and Mn divanadates (MV2O6, M2+ = Cu2+ and/or Mn2+). In this work, MV2O6 was synthesized, and its electrical conductivity and dielectric properties were studied. The electrical and dielectric properties were investigated in a frequency range of 0.1-300 kHz and a temperature range of 298 K to 573 K. The results indicate that the DC conductivity, AC conductivity, dielectric constant, dielectric loss factor, and loss tangent of the investigated materials increase with temperature, which support the contribution of grains and grain boundaries to the electrical properties. The materials exhibit non-Debye type relaxation, as indicated by the progression of the relaxation frequency. As frequency increases, the activation energy of AC conduction decreases, indicating that hopping conduction is the dominant mechanism. In all samples, the DC conduction activation energy is higher than the AC conduction activation energy. The circuit model was used to estimate the relaxation times. The results revealed remarkable dielectric characteristics, notably higher dielectric loss tangent values at frequencies below 1 kHz. Consequently, these materials can be used as electromagnetic attenuation absorbers. Graphical Abstract

Hydrogel composition and mechanical stiffness of 3D bioprinted cell-loaded scaffolds promote cartilage regeneration

ObjectiveTo investigate the impact of different component ratios and mechanical stiffness of the gelatin-sodium alginate composite hydrogel scaffold, fabricated through 3D bioprinting, on the viability and functionality of chondrocytes.MethodsThree different concentrations of hydrogel, designated as low, medium, and high, were prepared. The rheological properties of the hydrogel were characterized to optimize printing parameters. Subsequently, the printability and shape fidelity of the cell-loaded hydrogel scaffolds were statistically evaluated, and the chondrocyte viability was observed. Dynamic mechanical analysis was conducted to measure the modulus, thereby assessing the scaffold’s stiffness. Following a 21-day culture period, RT-PCR, histological staining, and immunostaining were employed to assess chondrocyte activity, chondrosphere aggregates formation, and cartilage matrix production.ResultsBased on rheological analysis, optimal printing temperatures for each group were determined as 27.8°C, 28.5°C, and 30°C. The optimized printing parameters could ensure the molding effect of the scaffolds on the day of printing, with the actual grid area of the scaffolds was close to the theoretical grid area. And the scaffolds exhibited good cell viability (93.24% ± 0.99%, 92.04% ± 1.49%, and 88.46% ± 1.53%). After 7 days of culture, the medium and high concentration groups showed no significant change in grid area compared to the day of printing (p > 0.05), indicating good morphological fidelity. As the hydrogel’s bicomponent ratio increased, both the storage modulus and loss modulus increased, while the loss factor remained relatively constant. The highest number of chondrocytes-formed chondrosphere aggregates in the medium concentration group was observed by light microscopy. RT-PCR results indicated significantly higher expression levels of chondrogenic genes SOX9, Agg, and Col-II in the low and medium concentration groups compared to the high concentration group (p < 0.05). Histological staining results showed that the middle concentration group formed the highest number of typical cartilage lacunae.ConclusionThe aforementioned results indicate that in 3D bioprinted cell-loaded GA-SA composite hydrogel scaffolds, the scaffolds with the composition ratio (10:3) and mechanical stiffness (∼155 kPa) exhibit sustained morphological fidelity, effectively preserve the hyaline phenotype of chondrocytes, and are more conducive to cartilage regeneration.

Assessment of the Audiological Profile and Related Risk Factors for Sensorineural Hearing Loss in Children with Speech and Language Delay

Assessment of the Audiological Profile and Related Risk Factors for Sensorineural Hearing Loss in Children with Speech and Language Delay

Evaluation of Inherent Damping Feature of Beam Structure Based on Complex Modulus

Structural damping, which has been widely used to quantify the energy dissipation of engineering structures, plays an important role in dynamic analysis during the design phase and the assessment of existing structures. However, the development of an accurate damping model remains an open question due to the unclear mechanism. In this study, structural damping was identified based on loss factors for beam structures, which were used for presenting the damping behavior during vibrations. The equation of motion for the bending deformation of a Timoshenko beam was derived, accounting for the material damping. To identify the loss factor of the beam from the response signals at a limited number of measurement points, an inverse algorithm based on wave coefficient estimation was developed, considering the numerical stability for data interpretation. Based on the proposed loss factor identification method, several beam models with different shapes of cross-sections were investigated, focusing on the feasibility of the method of varying cross-section cases. Comparing the spectral element model with the loss factor and the finite element model with Rayleigh damping, it was confirmed that the loss factor can better describe the actual energy dissipation behavior of the structure. It provides a more accurate theoretical model for estimating structural damping in practical engineering.