Conductive Loss Research Articles

Intra Operative Middle Ear Surprise Presenting with Unilateral Conductive Hearing Loss in an Intact Ear Drum - An Interesting Case Report

Intra Operative Middle Ear Surprise Presenting with Unilateral Conductive Hearing Loss in an Intact Ear Drum - An Interesting Case Report

The effect of conduction loss on microwave absorption performance of Fe-doped NiCo2O4 spinel oxide

Strong absorption and large bandwidth are two contributors to material’s electromagnetic wave absorbing performance. While spinel ferrite materials have garnered extensive attention in the realm of microwave absorption, their relatively low conductivity remains a practical challenge.In this work, NiCo2-xFexO4 (x = 0, 0.04, 0.06 and 0.08) precursor was prepared by hydrothermal and after-sintered method. It was found that Fe doping exhibit excellent EM absorption properties. Specially, when the Fe content is 0.08, the maximum reflection loss −48.90 dB at 15.40 GHz and the maximum effective bandwidth 4.20 GHz are achieved. More importantly, the absorption frequency can be broadened from Ku to C band even to S band with proper adjusting Fe content. Doping with Fe enhances conduction loss and make a significant contribution to dielectric loss, as a result, the impedance matching degree of the Fe-NiCo2O4 composite is influenced by the synergistic effect of its dielectric and magnetic properties. This work provides a simple way for enhancing the microwave absorption capabilities of ferrite materials and provides insight into understanding conduction loss in microwave absorption.

Classification of ossicular fixation based on a computational simulation of ossicular mobility

Ossicular fixation disturbs the mobility of the ossicular chain and causes conductive hearing loss. To diagnose the lesion area, otologists typically assess ossicular mobility through intraoperative palpation. Quantification of ossicular mobility and evidence-based diagnostic criteria are necessary for accurate assessment of each pathology, because diagnosis via palpation can rely on the surgeons’ experiences and skills. In this study, ossicular mobilities were simulated in 92 pathological cases of ossicular fixation as compliances using a finite-element (FE) model of the human middle ear. The validity of the ossicular mobilities obtained from the FE model was verified by comparison with measurements of ossicular mobilities in cadavers using our newly developed intraoperative ossicular mobility measurement system. The fixation-induced changes in hearing were validated by comparison with changes in the stapedial velocities obtained from the FE model with measurements reported in patients and in temporal bones. The 92 cases were classified into four groups by conducting a cluster analysis based on the simulated ossicular compliances. Most importantly, the cases of combined fixation of the malleus and/or the incus with otosclerosis were classified into two different surgical procedure groups by degree of fixation, i.e., malleo-stapedotomy and stapedotomy. These results suggest that pathological characteristics can be detected using quantitatively measured ossicular compliances followed by cluster analysis, and therefore, an effective diagnosis of ossicular fixation is achievable.

Defect design and vacancy engineering of NiCo2Se4 spinel composite for excellent electromagnetic wave absorption

Vacancy engineering presents an appealing method for modifying the electronic structure of spinel architectures. However, based on well-defined vacancy concentrations, how to design anionic vacancies to modulate electromagnetic parameters as well as electromagnetic wave absorption (EMA) properties is less studied. Here, NiCo2Se4 spinel structures were prepared using different selenization methods, and the Se vacancy defect concentration was controlled by changing the annealing temperature, thus regulating the EMA properties. Among them, the design of the hollow structure effectively enhanced the EMA performance. Moreover, the increase of Se vacancy concentration increases the conductivity loss while regulating the electronic structure, and also acts as an unsaturated site to induce the formation of dipoles to optimize the polarization loss. The effective absorption bandwidth (EAB) of NiCo2Se4-130 reaches 8.48 GHz at 2.4 mm at the highest Se vacancy concentration. This work establishes a direct relationship between vacancy concentration and the electromagnetic wave dissipation capability, offering valuable insights for the development of advanced EMA materials.

High stable poly (terphenyl-co-fluorene quinuclidinium) anion exchange membrane for alkaline water electrolysis

Developing anion exchange membranes (AEMs) is an effective way to reduce the cost of water electrolyser systems and fuel cell systems because of the no requirement of platinum-group-metal (PGM) catalysts. However, low conductivity and poor stability are the bottlenecks that constrain its development. In this work, we propose a series of performance enhanced poly (terphenyl-co-fluorene quinuclidinium) (TPFQ) AEMs. The hydroxide conductivity of TPFQ-10 reached 178.5 mS cm−1 at 80 °C. The rigid fluorene group gives the membrane better dimensional stability (swelling ratio: 7.7% in pure water and 1.2% in 10 M NaOH at 80 °C for TPFQ-10). In particular, the membranes exhibit extremely high alkaline stability, with almost no conductivity loss over more than 2000 h in a 10 M NaOH solution. The AEM water electrolysers (AEMWEs) with nickel-alloy foam electrodes shows an excellent current density of 2.32 A cm−2 at 2.0 V. The AEMWEs can work steadily at a current density of 0.5 A cm−2 in 5 M NaOH at 80 °C for more than 500 h, with a low voltage rising rate of 56 μV h−1.

Chitosan/Microcrystalline Cellulose Overlaid rGO/Fe3O4 Films: Broadband Dielectric Spectroscopy Investigations

Hybrid and straightforward inorganic/organic composites that can be used simultaneously for energy storage are reported. Films from chitosan (Cs) with microcrystalline cellulose (MCC) implanted with reduced graphene oxide (rGO) and/or magnetic Fe3O4 nanoparticles were fabricated. The reinforcement of the Cs/MCC films with rGO and /or Fe3O4 was studied through Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy with energy dispersive electron spectroscopy. In addition, their magnetic, conductivity, dielectric constant, and dielectric loss behaviors were studied. The magnetic investigations of the two films loaded with Fe3O4 have supper paramagnetic behavior. The saturation magnetization was decreased with the presence of rGO. At lower frequencies, the contribution of charge transport and interfacial polarization causes a sudden and nearly linear increase in permittivity with decreasing frequency. Unfortunately, no indication of electrode polarization was found, which reduces the ability of the prepared composition to store electrical energy. The electric modulus representation was employed to determine the relaxation time of the interfacial polarization quantitatively and numerically. No indication of electrode polarization was found.

Comparison of Air Conduction and Bone Conduction Masseter Vestibular Evoked Myogenic Potential Between Neurotypical Young Adults and Individuals With Conductive Hearing Loss.

Introduction Masseter vestibular evoked myogenic potential (mVEMP) is an acoustically evoked potential recorded from the masseter muscle. It is a recent tool in the vestibular assessment battery that checks the integrity of the vestibulomasseteric reflex pathway, specifically for saccular function. Need of the study There is a small pool of subjects with cervical spondylitis and anomalies in the eye muscle where cervical vestibular evoked myogenic potential (cVEMP) and ocular vestibular evoked myogenic potential (oVEMP) tests cannot be performed. In such conditions, mVEMP is considered an appropriate tool to assess the vestibular function. Bone conduction (BC) mVEMP assesses vestibular function in individuals with conductive hearing loss having a significant air-bone gap (ABG). Hence, it is essential to establish a comparative normal range of values for air conduction (AC) and BC mVEMP. Aim of the study The study aimed to evaluate the vestibulomasseteric reflex pathway using AC and BC mVEMP for click and 500 Hz tone burst stimuli in neurotypical young adults and compare it to individuals with conductive hearing loss. Method Ten neurotypical (20 ears) young adults and five (10 ears) individuals with conductive hearing loss in the age range of 15-40 years without vestibular complaints were recruited for the study. The AC and BC mVEMP were recorded monaurally using click and 500 Hz tone burst stimuli for all the participants. Results For neurotypical young adults, the mean latencies of P1 and N1 for AC and BC mVEMP using click were 13.87±1.86 ms and 19.78±2.14 ms and 13.79±2.06 ms and 21.30±1.48 ms, respectively. The P1 and N1 mean latencies for AC and BC mVEMP using 500 Hz tone burst were 14.90±1.50 ms and 21.03±1.30 ms and 14.18±0.95 ms and 19.75±1.71 ms, respectively. For individuals with conductive hearing loss, the P1 and N1 mean latencies for AC and BC mVEMP using click were 15.37±1.46 ms and 20.65±2.65 ms and 15.41±0.68 ms and 21.07±1.45 ms, respectively. AC mVEMP responses were absent for 500 Hz tone burst stimuli. The P1 and N1 mean latencies for BC mVEMP using 500 Hz tone burst stimuli were 14.96±0.6 ms and 22.72±1.42 ms, respectively. Conclusion AC mVEMP was absent for 500 Hz tone burst stimulus but present for click stimulus in individuals with conductive hearing loss as there was a larger ABG at the low frequencies than at the mid-high frequencies. BC mVEMP was present for click and 500 Hz tone burststimuli in all individuals with conductive hearing loss and latencies of P1 and N1 were similar to results obtained for neurotypical young adults and no significant difference was seen.

A novel synthesis of porous Ba2Co2Mn1.2Fe10.8O22/carbon composites for high efficiency electromagnetic wave absorption

Designing an electromagnetic wave (EMW) absorbing material with ultra-wide effective absorption bandwidth (EAB) and low filling ratio is the key to solving the problem of electromagnetic pollution. In this study, the porous Ba2Co2Mn1.2Fe10.8O22/C (Mn-Co2Y/C) composites were prepared by radial freeze-drying method as well as high temperature carbonization process (400 °C, 500 °C, 600 °C, and 700 °C). The research results indicate that the sample annealed at 600 °C exhibits superior EMW absorption properties, achieving the widest EAB of 5.77 GHz at a thickness of 1.7 mm, which is attributed to the synergistic effect of multiple reflections of EMWs within microchannels of the samples and the interfacial polarization between Mn-Co2Y ferrite and C material. Samples prepared at 600 °C have the best impedance matching, which makes it easier for EMWs to enter the material, thus exhibiting better EMW absorption performance. The magnetic loss mainly originates from natural resonance at low frequencies and eddy current loss at high frequencies, and the dielectric loss stems from relaxation loss and conductivity loss.

Xylem embolism induced by freeze-thaw and drought are influenced by different anatomical traits in subtropical montane evergreen angiosperm trees.

Subtropical evergreen broadleaved forests distributed in montane zones of southern China experience seasonal droughts and winter frost. Previously, studies have recognized that xylem anatomy is a determinant of its vulnerability to embolism caused by drought and freezing events. We hypothesized that there is a coordination of xylem resistance to freeze-thaw and drought-induced embolism for the subtropical montane evergreen broadleaved tree species because they are influenced by common xylem structural traits (e.g., vessel diameter). We examined the branch xylem anatomy, resistance to drought-induced embolism (P50), and the percent loss of branch hydraulic conductivity after a severe winter frost (PLCwinter) for 15 evergreen broadleaved tree species in a montane forest in South China. Our results showed that P50 of the studied species ranged from -2.81 to -5.13 MPa, which was not associated with most xylem anatomical properties except for the axial parenchyma-to-vessel connectivity. These tree species differed substantially in PLCwinter, ranging from 0% to 76.41%. PLCwinter was positively related to vessel diameter and negatively related to vessel density, vessel group index, and vessel-to-vessel connectivity, but no coordination with P50. This study suggests that hydraulic adaptation to frost is important to determine the distributional limit of subtropical montane evergreen woody angiosperms.

Theoretical analysis of structural, electronic, optical, and thermoelectric properties of XNaH2 (X = K, Rb) hybrid metal hydride composites

Abstract Hydrogen storage has become a global challenge for scientists of this era because it is an economical, clean, and non-pollutant element present in nature. In the present work, the DFT study of structural, electronic, optical, and thermoelectric properties of metal hydride XNaH2 (X = K, Rb) has been performed. Both of these materials are found stable in ambient conditions having semiconductor nature. The optical properties have been investigated in terms of dielectric function, refractive index, absorption coefficient, extinction coefficient, optical conductivity, reflectivity, and energy loss function. The better thermoelectric profile of these composites computed from the BoltzTraP2 code to shows their remarkable thermoelectric response between 200 to 950 K temperature. Remarkably, the computational calculations of these hydrides are made, which could lead to outstanding advancements in applications for hydrogen storage.

Reimagining otitis media diagnosis: A fusion of nested U-Net segmentation with graph theory-inspired feature set

Otitis media (OM) is a common infection or inflammation of the middle ear causing conductive hearing loss that primarily affects children and may delay speech, language, and cognitive development. OM can manifest itself in different forms, and can be diagnosed using (video) otoscopy (visualizing the tympanic membrane) or (video) pneumatic otoscopy and tympanometry. Accurate diagnosis of OM is challenging due to subtle differences in otoscopic features. This research aims to develop an automated computer-aided design (CAD) system to assist clinicians in diagnosing OM using otoscopy images. The ground truths, generated manually and validated by otolaryngologists, are utilized to train the proposed nested U-Net++ model. Ten clinically relevant gray level co-occurrence matrix (GLCM) and morphological features were extracted from the segmented Region of Interest (ROI) and validated for OM classification based on a statistical significance test. These features serve as input for a Graph Neural Network (GNN) model, the base model in our research. An optimized GNN model is proposed after ablation study of the base model. Three datasets, one private dataset, and two public ones have been used, where the private dataset is utilized for both training and testing, and the public datasets are used to test the robustness of the proposed GNN model only. The proposed GNN model obtained the highest accuracy in diagnosing OM: 99.38 %, 93.51 %, and 91.38 % for the private dataset, public dataset1, and public dataset2, respectively. The proposed methodology and results of this research might enhance clinicians' effectiveness in diagnosing OM.

A Rare Presentation Of Osteoma Of External Auditory Canal

Osteoma of external auditory canal is a rare, slow growing benign tumor with an estimated incidence of 0.05%. Osteoma in external auditory canal is usually asymptomatic but can cause symptoms such as conductive hearing loss, aural fullness in large osteoma occluding the external auditory canal. Osteoma is diagnosed by clinical presentation, radiological and histological investigations. We present a case report of 28year old female with left external auditory canal osteoma with dehiscent facial ridge and complete tympanic membrane and malleus erosion

Speech intelligibility prediction based on a physiological model of the human ear and a hierarchical spiking neural network.

A speech intelligibility (SI) prediction model is proposed that includes an auditory preprocessing component based on the physiological anatomy and activity of the human ear, a hierarchical spiking neural network, and a decision back-end processing based on correlation analysis. The auditory preprocessing component effectively captures advanced physiological details of the auditory system, such as retrograde traveling waves, longitudinal coupling, and cochlear nonlinearity. The ability of the model to predict data from normal-hearing listeners under various additive noise conditions was considered. The predictions closely matched the experimental test data under all conditions. Furthermore, we developed a lumped mass model of a McGee stainless-steel piston with the middle-ear to study the recovery of individuals with otosclerosis. We show that the proposed SI model accurately simulates the effect of middle-ear intervention on SI. Consequently, the model establishes a model-based relationship between objective measures of human ear damage, like distortion product otoacoustic emissions, and speech perception. Moreover, the SI model can serve as a robust tool for optimizing parameters and for preoperative assessment of artificial stimuli, providing a valuable reference for clinical treatments of conductive hearing loss.

Enhanced electromagnetic wave absorption performance of Ta₄C₃Tx MXenes with optimized interlayer spacing via hydrofluoric acid etching

Ta4C3Tx MXene, a novel two-dimensional material, shows significant application potential for electromagnetic wave (EMW) absorption because of its unique layered structure and high conductivity. In this study, hydrofluoric acid etching was used to obtain Ta4C3Tx MXenes with varying interlayer spaces by adjusting the etching duration, which enhanced the EMW absorption performance. The impact of interlayer spacing on the EMW absorption performance of Ta4C3Tx MXene was systematically evaluated for the first time. The results show that the sample etched with hydrofluoric acid for 48 h (S2-48 h) exhibited the best EMW absorption performance. For S2-48 h, the optimal reflection loss (RL) value was −33.53 dB at a frequency of 9.74 GHz and a thickness of 1.4 mm. In addition, the widest effective absorption bandwidth was 2.97 GHz (10.73–13.7 GHz), which was achieved at a frequency of 11.72 GHz and a thickness of 1.2 mm. This outstanding performance is mainly attributed to good impedance matching and multiple loss mechanisms induced by the etching process, including conduction loss, dipolar polarization, interfacial polarization, and multiple RLs. Furthermore, this research expands the application potential of two-dimensional MXene materials in EMW absorption.

Ultralight and rigid PBO nanofiber aerogel with superior electromagnetic wave absorption properties

Polymer-based aerogels are emerging as promising candidates for lightweight and high performance electromagnetic (EM) wave absorption materials. In this study, an ultralight and rigid poly(p-phenylene benzobisoxazole) nanofiber (PNF) based composite aerogel with excellent EM wave absorption performance was fabricated with cobalt-nickel alloy (CoNi) nanoparticles and carbon nanotubes (CNTs) as magnetic and conductive fillers, respectively. A CNT/PNF composite aerogel was first prepared through a sol-gel and freeze-drying method, and then CoNi nanoparticles were introduced therein through hydrothermal reaction and thermal annealing to obtain the CoNi/CNT/PNF aerogel. CNTs and PNFs were interwoven and constructed a three-dimensional conductive/magnetic cage-like skeleton structure decorating with magnetic CoNi nanoparticles. The cage-like skeleton structure allowed the dissipation of EM waves through multiple mechanisms encompassing conduction loss, magnetic loss, multiple reflection, scattering, and absorption. When its thickness was 4 mm, the CoNi/CNT/PNF aerogel showed a minimal reflection loss of −44.7 dB (at 6.88 GHz), and its broad effective absorption bandwidth covered the entire X-band and Ku-band and most of the C-band (12.32 GHz, from 5.68 GHz to 18 GHz). In addition, the rigid aerogel exhibited an ultralow density (0.107 g/cm3), excellent thermal insulation, and flame retardancy, demonstrating its potential application as a high-performance EM wave absorption material in the fields of aerospace and national defense.

Lightweight Fe3O4/Fe/C/rGO multifunctional aerogel for efficient microwave absorption, electromagnetic interference shielding, hydrophobicity and thermal insulation

Effective integration of multiple functions into microwave absorbing materials is a future development direction, but still remains a significant challenge. This work fabricated a lightweight, multifunctional aerogel through electrostatic self-assembly, freeze-drying and in-situ pyrolysis process, achieving an in-situ composite of magnetic/dielectric components. The regulated pyrolysis temperature achieves a good balance between abundant nanopores and heterogeneous interfaces, enriched defects, and conductivity. This balance induced a synergy of dielectric loss, magnetic loss, and conduction loss at low frequencies, improving the impedance matching. The aerogel obtains a minimum reflection loss (RLmin) of −65.17 dB in the low-frequency range and a maximum effective absorption bandwidth (EABmax) of 5.76 GHz. The radar cross section (RCS) simulation confirmed its good stealth performance. In addition, an increase in aerogel loading enhanced its electrical conductivity, resulting in a higher electromagnetic interference (EMI) shielding effectiveness (SE) of 81.83 dB, the specific shielding effectiveness (SSE) up to 359.28 dB·cm3/g and the absolute shielding effectiveness (SSEt) up to 1596.82 dB·cm2/g. Beyond microwave absorption and shielding, this aerogel also exhibited good hydrophobicity and thermal insulation. This study provides a new perspective for the development of materials with microwave absorption properties in low-frequency bands and multifunctional properties for broader applications in military, communication, aerospace, and other fields.

The cation exchange driving multi-phase regulation in Co7Fe3/Co@NC for enhanced broadband electromagnetic wave absorption

Phase engineering offers distinctive advantages in designing efficient electromagnetic wave (EMW) absorbers. The manipulation of the interaction and arrangement of different multi-phase systems enables the achievement of more precise EMW absorption. However, the transition mechanism from single metal phases to metal/alloy phases has not yet been fully revealed. Here, we employ multiphase engineering driven by cation exchange reactions to finely control the proportion of Co/Co7Fe3 phases and regulate electromagnetic parameters. The introduction of cavities and heteroatoms through cation exchange enables optimized defect distribution and composition, which enhances both impedance matching and electromagnetic attenuation capabilities. Specifically, we yield hollow Co7Fe3/Co@N-doped carbon (H-Co7Fe3/Co@NC) embedded in high-crystallinity graphite carbon after high-temperature pyrolysis, which promotes significant electron transfer between phases, thus enhancing conduction and polarization losses. H-Co7Fe3/Co@NC exhibits ultra-strong reflection loss (RL) of −59.70 dB at 9.37 GHz and achieves broadband absorption of 6.01 GHz at 2.1 mm. This study highlights the influence of Co7Fe3/Co heterogeneous structures on absorption performance and validates the electromagnetic response mechanism of multi-phase heterostructures through COMSOL finite element simulation analysis. Thus, this work paves the way for applying multi-phase engineering driven by cation exchange reactions for advanced absorbers.

Enhanced High-Temperature performance of PEI dielectrics via deep trap energy levels and physically crosslinked effects

Dielectric capacitors are indispensable energy storage components in both civilian applications and industrial processes. Under elevated temperatures and intense electric fields, polymer dielectrics usually suffer from an inevitably increase in conductivity, leading to a significant reduction in breakdown strength, energy density and efficiency. This investigation aims to design an all-organic dielectric with enhanced high-temperature capacitive performance by introducing a small molecule P-xylene F (PF) into polyetherimide (PEI). Two mechanisms including the incorporation of deep trap energy levels via wide bandgap fillers and the electrostatic interactions by hydrogen bonding between the fillers and the polymer matrix are proposed to support the enhancement. The hydrogen bonding between PF and polyamic acid (PAA)chains induces the formation of physical cross-linking between PF and the negatively charged benzene rings in PEI after imidization. This influences benzene ring stacking within the polymer chains and enhances the film’s mechanical strength. Additionally, PF’s wider bandgap compared to PEI introduces deep trap energy levels, hindering carrier transport and reducing conductive losses at high temperatures. As results, the dielectric achieves an energy density (Ud) of 4.47 J/cm3 with an efficiency (η) above 90 % at 200 °C. Its excellent stability is also demonstrated with over 210,000 charge–discharge cycles at 200 °C. This study promotes the development of high-performance dielectrics at high temperature.

Engineering multifunctionality graphene-based nanocomposites with epoxy-silane functionalized cardanol for next-generation microwave absorber

As technology advances, the demand for effective microwave-absorbing materials (MAM) to mitigate electromagnetic wave interference is growing. Two-dimensional (2D) materials are increasingly favored across various fields for their high specific surface area, electrical conductivity, low density, and dielectric loss properties. This study presents lightweight nanocomposites composed of graphene nanoplatelets blended with epoxy resin (ER) and cardanol with silane-functionalized (SFC) as a toughening agent. The resulting nanocomposites exhibit a high surface roughness of 130 nm and an enhanced hydrophobicity, as evidenced by a high contact angle. Notably, the ER/SFC/GNP sample at 3 wt% (0.075 g) achieves a minimum reflection loss value of −18 dB at a thickness of 10 mm, indicating improved impedance matching and enhanced dielectric loss capability. The increasing damping factor ratio to approximately 0.95 further augments the reflection loss performance. The research aims to develop cost-effective, efficient, lightweight graphene-based nanocomposite absorbers.

Studies on the improvement of thermal, dielectric and optical properties of poly(2,2,2-trifluoroethyl methacrylate) by the addition of graphite oxide as fillers

ABSTRACT In this study, poly(2,2,2-trifluoroethyl methacrylate) homopolymer (PTFEMA) was synthesized via free radical polymerization method, and its composites with graphite oxide (GO) were prepared to improve its dielectric and thermal properties. Thermogravimetric evaluation revealed that graphite oxide acts to limit thermal diffusion throughout the PTFEMA loaded graphite oxide (GO) composite, and hence, thermal stability of composites improved. While the initial decomposition temperature of pure PTFEMA was found to be 233°C from thermogravimetric analysis measurements, the initial decomposition temperature of PTFEMA containing 5 wt% graphite oxide was found to be 251°C. The glass transition temperatures of the composites increased from 76°C to 86°C due to the increase in the amount of graphite oxide added to PTFEMA. The dielectric properties of composites were investigated from 100 Hz to 10 kHz for different temperatures. While the dielectric constant, ε′, of pure PTFEMA at 1 kHz at room temperature was found to be 3.00, that of the PTFEMA containing 5 wt% GO was found 10.32. Therefore, graphite oxide doped PTFEMA composites may be suitable candidates for energy storage applications. The dc conductivity and dielectric loss factor of PTFEMA containing 5 wt% graphite oxide were seen to increase with temperature.