Anisotropic Semicrystalline Homopolymer Dielectrics for High-Temperature Capacitive Energy Storage.

High-temperature dielectric polymers are in high demand for powering applications in extreme environments. Here, we have developed high-temperature homopolymer dielectrics with anisotropy by leveraging the hierarchical structure in semicrystalline polymers. The lamellae have been aligned parallel to the surface in the dielectric films. This structural arrangement resembles the horizontal alignment of nanosheet fillers in polymer nanocomposites and nanosheet-like lamellae in block copolymers, which has been proven to provide the optimal topological structure for electrical energy storage. The unique ordering of lamellae in our dielectric films endue a significantly increased breakdown strength and a reduced leakage current compared to amorphous films. This novel approach of enhancing the capacitive energy storage properties by controlled orientation of lamellae in homopolymer offers a new perspective for the design of high-temperature polymer dielectrics.

Study on the Preparation and Process Parameter-Mechanical Property Relationships of Carbon Fiber Fabric Reinforced Poly(Ether Ether Ketone) Thermoplastic Composites.

Carbon fiber fabric-reinforced poly(ether ether ketone) (CFF-PEEK) composites exhibit exceptional mechanical properties, and their flexibility and conformability make them a promising alternative to traditional prepregs. However, the formation of the CFF-PEEK composite is trapped in the high viscosity of PEEK, the smooth surface, and tightly interwoven bundles of CFF. It is more difficult for the resin to flow through the fibers of complex textile structures. Here, a simple film stacking method using the hot-pressing process of plain-woven CFF-PEEK thermoplastic composites is discussed. The uniform distribution of PEEK resin between each layer of CFF reduces the flow distance during the molding process, preventing defects in the composite material effectively. Four process parameters, including molding temperature (370, 385, 400, and 415 °C), molding pressure (1, 2, 4, 8, and 10 MPa), molding time (10, 20, 30, 40, 60, and 90 min), and pre-compaction process, are considered. Interlaminar shear strength (ILSS), tensile strength, and flexural strength of CFF/PEEK composites are evaluated to optimize the process parameters. Moreover, ultrasonic scanning microscopy and scanning electron microscopy are employed to observe the formation quality and microscopic failure modes of CFF/PEEK composites, respectively. The ultimate process parameters are a molding temperature of 410 °C, molding pressure of 10 MPa, molding time of 60 min, and the need for the pre-compaction process. Under the best process parameters, the ILSS is 62.5 MPa, the flexural strength is 754.4 MPa, and the tensile strength is 796.1 MPa. This work provides valuable insight for studying the process parameters of fiber fabric-reinforced thermoplastic polymer composites and revealing their impact on mechanical properties.

Synthesis and Characterization of Phenazine-Based Redox Center for High-Performance Polymer Poly(aryl ether sulfone)-5,10-Diphenyl-dihydrophenazine.

Phenazine-based redox-active centers are capable of averting chemical bond rearrangements by coupling during the reaction process, leading to enhanced stabilization of the material. When introduced into a high-performance polymer with excellent physicochemical properties, they can be endowed with electrochemical properties and related prospective applications while maintaining the capabilities of the materials. In this study, a facile C-N coupling method was chosen for the synthesis of serial poly(aryl ether sulfone) materials containing phenazine-based redox-active centers and to explore their electrochemical properties. As expected, the cyclic voltammetry curves of PAS-DPPZ-60, which basically overlap after thousands of cycles, indicate the stability of the electrochemical properties. As an electrochromic material, the transmittance change in PAS-DPPZ-60 exhibits only a slight attenuation after as long as 600 cycles. Meanwhile, as an organic battery cathode material, PAS-DPPZ has a theoretical specific capacity of 126 mAh g-1, and the capacity retention rate is 82.6% after 100 cycles at a 0.1 C current density. The perfect combination of advantageous features between phenazine and poly(aryl ether sulfone) is considered to be the reason for the favorable electrochemical performance of the material series.

The mediating and moderating effects of resilience on the relationship between sleep quality and psychological distress in Chinese women with infertility.

BACKGROUND: Research has widely indicated that the psychological distress experienced by infertile patients during fertility treatments may have a negative effect on the results of assisted reproduction. Although numerous studies have shown that psychological resilience and sleep quality are important influencing factors for psychological distress, the mediating mechanisms of psychological resilience in the relationship between sleep quality and psychological distress for Chinese women in particular remain unclear. Therefore, the current study investigates the association between sleep quality, resilience, and psychological distress in Chinese women with infertility and examines the mediating and moderating roles of resilience on the relationship between sleep quality and psychological distress. METHODS: In this cross-sectional study, a total of 595 women with infertility who were undergoing IVF-ET were recruited at the Reproductive Medicine, Shandong University, from April to November 2019. Participants were instructed to complete four questionnaires, including a questionnaire about socio-demographic and clinical-related information, the Pittsburgh Sleep Quality Index (PSQI), the 10-item Connor-Davidson Resilience Scale (CD-RISC-10), and the Kessler-10 (K10). Pearson's correlation analysis was conducted preliminarily to describe the relationships between sleep quality, resilience, and psychological distress. A mediation model and a moderated model were constructed and analyzed using the PROCESS macro for SPSS. The Johnson-Neyman (J-N) technique was then used to identify the regions of significance across the levels of moderator values. RESULTS: Patients in the sample had a high prevalence of psychological distress (48.6%, K10 scores > 22), and mediation analysis indicated that resilience played a partially mediating role in the relationship between sleep quality and psychological distress (indict effect = 0.072, P < 0.001). Moderation analysis indicated that resilience also moderated the association between sleep quality and psychological distress. CONCLUSIONS: Resilience may play a key role in the relationship between sleep quality and psychological distress. Our findings imply that resilience training may therefore be an effective component of psychological distress intervention in women with infertility.

Estrogen receptor GPR30 in the anterior cingulate cortex mediates exacerbated neuropathic pain in ovariectomized mice.

Menopausal women experience neuropathic pain 63% more frequently than men do, which may attribute to the estrogen withdrawal. However, the underlying mechanisms remain unclear. Here, the role of estrogen receptors (ERs) in ovariectomized (OVX) female mice following chronic constriction injury (CCI) was investigated. With 17ß-estradiol (E2) supplemented, aggravated mechanical allodynia in OVX mice could be significantly alleviated, particularly after intra-anterior cingulate cortex (ACC) E2 delivery. Pharmacological interventions further demonstrated that the agonist of G-protein-coupled estrogen receptor 30 (GPR30), rather than ERα or ERß in the ACC, exhibited the similar analgesic effect as E2, whereas antagonist of GPR30 exacerbated allodynia. Furthermore, OVX surgery reduced GPR30 expression in the ACC, which could be restored with estrogen supplementation. Selective downregulation of GPR30 in the ACC of naïve female mice induces mechanical allodynia, whereas GPR30 overexpression in the ACC remarkedly alleviated OVX-exacerbated allodynia. Collectively, estrogen withdrawal could downregulate the ACC GPR30 expression, resulting in exacerbated neuropathic pain. Our findings highlight the importance of GPR30 in the ACC in aggravated neuropathic pain during menopause, and offer a potential therapeutic candidate for neuropathic pain management in menopausal women.

Constructing Novel High Dielectric Constant Polyimides Containing Dipolar Pendant Groups with Enhanced Orientational Polarization.

Polymer dielectrics with high dielectric constant are urgently demanded for potential electrical and pulsed power applications. The design of polymers with side chains containing dipolar groups is considered an effective method for preparing materials with a high dielectric constant and low loss. This study synthesizes and comprehensively compare the dielectric properties of novel polyimides with side chains containing urea (BU-PI), carbamate (BC-PI), and sulfonyl (BS-PI) functional groups. The novel polyimides exhibit relatively high dielectric constant and low dielectric loss values due to the enhanced orientational polarization and suppressed dipole-dipole interactions of dipolar groups. In particular, BU-PI containing urea pendant groups presents the highest dielectric constant of 6.14 and reasonably low dielectric loss value of 0.0097. The strong γ transitions with low activation energies derived from dielectric spectroscopy measurements have been further evaluated to demonstrate the enhanced free rotational motion of urea pendant dipoles. In energy storage applications, BU-PI achieves a discharged energy density of 6.92 J cm-3 and a charge-discharge efficiency above 83% at 500 MV m-1. This study demonstrates that urea group, as dipolar pendant group, can provide polymers with better dielectric properties than the most commonly used sulfonyl groups.

Ultraviolet-Irradiated All-Organic Nanocomposites with Polymer Dots for High-Temperature Capacitive Energy Storage.

Polymer dielectrics capable of operating efficiently at high electric fields and elevated temperatures are urgently demanded by next-generation electronics and electrical power systems. While inorganic fillers have been extensively utilized to improved high-temperature capacitive performance of dielectric polymers, the presence of thermodynamically incompatible organic and inorganic components may lead to concern about the long-term stability and also complicate film processing. Herein, zero-dimensional polymer dots with high electron affinity are introduced into photoactive allyl-containing poly(aryl ether sulfone) to form the all-organic polymer composites for high-temperature capacitive energy storage. Upon ultraviolet irradiation, the crosslinked polymer composites with polymer dots are efficient in suppressing electrical conduction at high electric fields and elevated temperatures, which significantly reduces the high-field energy loss of the composites at 200 °C. Accordingly, the ultraviolet-irradiated composite film exhibits a discharged energy density of 4.2 J cm-3 at 200 °C. Along with outstanding cyclic stability of capacitive performance at 200 °C, this work provides a promising class of dielectric materials for robust high-performance all-organic dielectric nanocomposites.

A Polytetrafluoroethylene-Based Solvent-Free Procedure for the Manufacturing of Lithium-Ion Batteries.

Lithium-ion batteries (LIBs) have recently become popular for energy storage due to their high energy density, storage capacity, and long-term cycle life. Although binders make up only a small proportion of LIBs, they have become the key to promoting the transformation of the battery preparation process. Along with the development of binders, the battery manufacturing process has evolved from the conventional slurry-casting (SC) process to a more attractive solvent-free (SF) method. Compared with traditional LIBs manufacturing method, the SF method could dramatically reduce and increase the energy density due to the reduced preparation steps and enhanced electrode loading. Polytetrafluoroethylene (PTFE), as a typical binder, has played an important role in fabricating high-performance LIBs, particularly in regards to the SF technique. In this paper, the development history and application status of PTFE binder was introduced, and then its contributions and the inherent problems involved in the SF process were described and analyzed. Finally, the viewpoints concerning the future trends for PTFE-based SF manufacturing methods were also discussed. We hope this work can inspire future research concerning high-quality SF binders and assist in promoting the evolution of the SF manufacturing technology in regards to LIBs.

Sexual dimorphic distribution of G protein-coupled receptor 30 in pain-related regions of the mouse brain.

Sex differences in pain sensitivity have contributed to the fact that medications for curing chronic pain are unsatisfactory. However, the underlying mechanism remains to be elucidated. Brain-derived estrogen participates in modulation of sex differences in pain and related emotion. G protein-coupled receptor 30 (GPR30), identified as a novel estrogen receptor with a different distribution than traditional receptors, has been proved to play a vital role in regulating pain affected by estrogen. However, the contribution of its distribution to sexually dimorphic pain-related behaviors has not been fully explored. In the current study, immunofluorescence assays were applied to mark the neurons expressing GPR30 in male and female mice (in metestrus and proestrus phase) in pain-related brain regions. The neurons that express CaMKIIα or VGAT were also labeled to observe overlap with GPR30. We found that females had more GPR30-positive (GPR30+ ) neurons in the primary somatosensory (S1) and insular cortex (IC) than males. In the lateral habenula (LHb) and the nucleus tractus solitarius (NTS), males had more GPR30+ neurons than females. Moreover, within the LHb, the expression of GPR30 varied with estrous cycle phase; females in metestrus had fewer GPR30+ neurons than those in proestrus. In addition, females had more GPR30+ neurons, which co-expressed CaMKIIα in the medial preoptic nucleus (mPOA) than males, while males had more than females in the basolateral complex of the amygdala (BLA). These findings may partly explain the different modulatory effects of GPR30 in pain and related emotional phenotypes between sexes and provide a basis for comprehension of sexual dimorphism in pain related to estrogen and GPR30, and finally provide new targets for exploiting new treatments of sex-specific pain.

Common institutional investors and the quality of management earnings forecasts-Empirical and machine learning evidences.

Based on the data of the Chinese A-share listed firms in China Shanghai and Shenzhen Stock Exchange from 2014 to 2021, this article explores the relationship between common institutional investors and the quality of management earnings forecasts. The study used the multiple linear regression model and empirically found that common institutional investors positively impact the precision of earnings forecasts. This article also uses graph neural networks to predict the precision of earnings forecasts. Our findings have shown that common institutional investors form external supervision over restricting management to release a wide width of earnings forecasts, which helps to improve the risk warning function of earnings forecasts and promote the sustainable development of information disclosure from management in the Chinese capital market. One of the marginal contributions of this paper is that it enriches the literature related to the economic consequences of common institutional shareholding. Then, the neural network method used to predict the quality of management forecasts enhances the research method of institutional investors and the behavior of management earnings forecasts. Thirdly, this paper calls for strengthening information sharing and circulation among institutional investors to reduce information asymmetry between investors and management.

InSitu Integrated Fabrication for Multi-Interface Stabilized and Highly Durable Polyaniline@Graphene Oxide/Polyether Ether Ketone Special Separation Membranes.

Special separation membranes are widely employed for separation and purification purposes under challenging operating conditions due to their low energy consumption, excellent solvent, and corrosion resistance. However, the development of membranes is limited by corrosion-resistant polymer substrates and precise interfacial separation layers. Herein, polyaniline (PANI) is employed to achieve insitu anchoring of multiple interfaces, resulting in the fabrication of polyaniline@graphene oxide/polyether ether ketone (PANI@GO/PEEK) membranes. Insitu growth of PANI achieves the adequate bonding of the PEEK substrate and GO separation interface, which solves the problem of solution processing of PEEK and the instability of GO layers. By bottom-up confined polymerization of aniline, it could control the pore size of the separation layer, correct defects, and anchor among polymer, nano-separation layer, and nano-sheet. The mechanism of membrane construction within the confined domain and micro-nano structure modulation is further explored. The membranes demonstrate exceptional stability realizing over 90% rejection in 2 m HCl, NaOH, and high temperatures. Additionally, -membranes exhibit remarkable durability after 240 days immersion and 100 h long-term operation, which display the methanol flux of 50.2 L m-2 h-1 and 92% rejection of AF (585 g mol-1 ). This method substantially contributes to special separation membranes by offering a novel strategy.

Semi-crystalline sulfonated poly(ether ketone) proton exchange membranes: The trade-off of facile synthesis and performance.

Improving the performance of proton exchange membranes (PEMs) through the synthesis of sulfonated polymers with elaborate molecular structures has received extensive approval. However, the tedious synthetic process and consequently high costs restrain their possible substitution for Nafion, a classic PEM material. Herein, a series of semi-crystalline sulfonated poly(ether ketone)s with fluorene-based units were prepared via direct copolymerization of commercially available monomers and followed post-sulfonation, namely SPEK-FD-x, where × represents the molar ratio of the fluorene-containing monomer to the employed bisphenol monomers. The entire synthetic pathway was facile without involving hardly accessible materials. Subsequently, various properties of SPEK-FD-x membranes were investigated and further compared with Nafion 117. Due to the formation of the well-defined hydrophilic-hydrophobic microphase separation morphology and the reinforcement of the PEK crystalline regions, the SPEK-FD-x membranes exhibited outstanding proton conductivity, resistance for methanol permeation, as well as dimensional, thermal, oxidative, and mechanical stability. Among them, the overall behavior of the SPEK-FD-25 membrane was comparable to or even greater than that of Nafion 117, most importantly, it also performed decently in both H2/air fuel cells and direct methanol fuel cells. Therefore, with the straightforward synthesis and superior performance, the SPEK-FD-x membranes may serve as a promising alternative to Nafion.

Efficient Fabrication of Carbon Nanotube-Based Stretchable Electrodes for Flexible Electronic Devices.

Stretchable electrodes are highly demanded in various wearable and flexible electronic devices, whereas the efficient fabrication approach is still a challenge. In this work, an efficient shrinking method to fabricate carbon nanotube (CNT)-based stretchable electrodes is proposed. The electrode is a layer of anisotropic CNT wrinkling film coated on a latex balloon substrate (CNT@latex), whose resistivity remains stable after 25 000 stretching cycles of 0 to 50% tensile strain, and can survive up to 500% tensile train. The highly conductive electrode can be used as the current collector of a stretchable Zinc-ion battery, maintaining an output voltage of 1.3 V during the stretching process of 0 to 100%. The applications of the electrode in flexible triboelectric nanogenerators and Joule heating devices are also demonstrated, further indicating their good prospects in the field of stretchable electronic devices.

Side-Chain-Type High Dielectric-Constant Dipolar Polyimides with Temperature Resistance.

Innovative dielectric materials with high-temperature resistance and outstanding dielectric properties have attracted tremendous attention in advanced electronical fields. Polyimide(PI) is considered a promising candidate for the modern electronic industry due to its excellent dielectric properties and comprehensive properties. However, the limited-adjustable range of dielectric constant and the difficulty to obtain a high dielectric constant restrict the application of PI as high dielectric materials. Herein, a novel diamine monomer (2,2'-bis((methylsulfonyl)methyl)-[1,1'-biphenyl]-4,4'-diamine (BSBPA)) containing a rigid biphenyl structure and high dipolar sulfonyl pendant groups is designed for high dielectric polyimides. The rigid biphenyl and polar sulfonyl pendant groups can reasonably optimize the molecular structure and orientational polarization of polyimides to improve their dielectric properties and thermal properties. Moreover, the effect of different bridge linkages on the dielectric properties is studied by using the different dianhydrides. Thus, the PI-BSBPA films especially the DSDA-BSBPA film (DSDA: 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride) achieve great thermal properties (T5%d of 377 °C and Tg of 358 °C) and excellent dielectric properties (6.95 at 1 kHz) along with high discharged energy density of 5.25 J cm-3 and charge-discharge efficiency of 90%. The collaborative control of main-chain and side-chain engineering is effective to endow the polyimides with high-temperature tolerance and high dielectric performance.

Research Progress in Special Engineering Plastic-Based Electrochromic Polymers.

SPECPs are electrochromic polymers that contain special engineering plastic structural characteristic groups (SPECPs). Due to their high thermal stability, mechanical properties, and weather resistance, they are also known as high-performance electrochromic polymer (HPEP or HPP). Meanwhile, due to the structural characteristics of their long polymer chains, these materials have natural advantages in the application of flexible electrochromic devices. According to the structure of special engineering plastic groups, SPECPs are divided into five categories: polyamide, polyimide, polyamide imide, polyarylsulfone, and polyarylketone. This article mainly introduces the latest research on SPECPs. The structural design, electrochromic properties, and applications of these materials are also introduced in this article, and the challenges and future development trends of SPECPs are prospected.

Multilayer Dielectric Nanocomposites with Cross-Linked Dielectric Transition Interlayers for High-Temperature Applications.

In energy storage and transportation systems, polymer dielectrics are widely applied in smart grids, electric vehicles, and power conditioning owing to their incomparable power density and high reliability. However, the dielectric constant (ε) and breakdown strength (Eb) normally cannot be increased simultaneously, which results in insufficient discharged energy density especially at high temperatures. In this work, enhanced Eb and high energy density are archived in multilayer polymer nanocomposites by introducing cross-linked dielectric transition layers. Specifically, the sandwiched composite achieves a huge discharge energy density of 4.64 J cm-3 with a charged-discharged efficiency of 84% at 150 °C and 500 MV m-1. The formation of cross-linked dielectric transition layers between layers of the multilayer nanocomposite could effectively restrain the growth of the electrical tree and greatly increase the Eb. This work presents a strategy for designing high-performance multilayered dielectric polymer nanocomposites by introducing cross-linked dielectric transition layers to reduce the loss from interlayer interfaces.

Combined-Acupoint Electroacupuncture Induces Better Analgesia via Activating the Endocannabinoid System in the Spinal Cord.

Electroacupuncture (EA) therapy has been widely reported to alleviate neuropathic pain with few side effects in both clinical practice and animal studies worldwide. However, little is known about the comparison of the therapeutic efficacy among the diverse EA schemes used for neuropathic pain. The present study is aimed at investigating the therapeutic efficacy discrepancy between the single and combined-acupoint EA and to reveal the difference of mechanisms behind them. Electroacupuncture was given at both Zusanli (ST36) and Huantiao (GB30) in the combined group or ST36 alone in the single group. Paw withdrawal mechanical threshold (PWMT) was measured to determine the pain level. Electrophysiology was performed to detect the effects of EA on synaptic transmission in the spinal dorsal horn of the vGlut2-tdTomato mice. Spinal contents of endogenous opioids, endocannabinoids, and their receptors were examined. Inhibitors of CBR (cannabinoid receptor) and opioid receptors were used to study the roles of opioid and endocannabinoid system (ECS) in EA analgesia. We found that combined-acupoint acupuncture provide stronger analgesia than the single group did, and the former inhibited the synaptic transmission at the spinal level to a greater extent than later. Besides, the high-intensity stimulation at ST36 or normal stimulation at two sham acupoints did not mimic the similar efficacy of analgesia in the combined group. Acupuncture stimulation in single and combined groups both activated the endogenous opioid system. The ECS was only activated in the combined group. Naloxone totally blocked the analgesic effect of single-acupoint EA; however, it did not attenuate that of combined-acupoint EA unless coadministered with CBR antagonists. Hence, in the CCI-induced neuropathic pain model, combined-acupoint EA at ST36 and GB30 is more effective in analgesia than the single-acupoint EA at ST36. EA stimulation at GB30 alone neither provided a superior analgesic effect to EA treatment at ST36 nor altered the content of AEA, 2-AG, CB1 receptor, or CB2 receptor compared with the CCI group. Activation of the ECS is the main contributor of the better analgesia by the combined acupoint stimulation than that induced by single acupoint stimulation.

Foreign body granuloma in the tongue differentiated from tongue cancer: A case report.

BACKGROUND: Embedded foreign bodies in the tongue are rarely seen in clinical settings. An untreated foreign body can cause a granuloma which often presents as an enlarged tongue mass. However, if foreign body ingestion status is unknown, physical examination and magnetic resonance imaging (MRI) tend to lead to suspicion of tongue cancer, especially in older patients. Thus, differential diagnosis of an enlarged tongue mass is important, especially because it is closely related to the choice of treatment method. CASE SUMMARY: A 61-year-old woman was admitted to the hospital with pain and noticeable swelling in the tongue that had persisted for over 1 mo. She had no previous medical history. MRI revealed abnormal signal intensities that were indicative of a neoplasm. Thus, the oral surgeon and radiologist arrived at a primary diagnosis of tongue cancer. The patient visited the Ear Nose and Throat Department for further consultation and underwent an ultrasound examination of the tongue. The ultrasonography was consistent with a linear hyperechoic foreign body which was indicative of an embedded foreign body (bone) in the tongue, even though the patient denied any history of foreign body ingestion. Complete surgical enucleation of the lesion was conducted. The mass which included a fish bone was completely removed. The post-operative pathological examination confirmed that the mass was a granuloma containing collagen fibers, macrophages and chronic inflammatory cells. The patient recovered without complications over a 2 mo follow-up period. CONCLUSION: We report a rare case of foreign body granuloma in the tongue that was primarily diagnosed as tongue cancer. The MRI and ultrasound examinations revealed a piece of bone in the left lateral aspect of the tongue. The granuloma, which contained a fish bone, was completely removed via surgery and confirmed via biopsy. Differential diagnosis of the enlarged tongue mass was critical to the selection of treatment method.

Structure-Activity Studies of N-Heterocyclic Benzoyl Arylamine Derivatives Led to a Highly Fungicidal Candidate against Gaeumannomyces graminis var. tritici and Four Fusarium Wheat Pathogens.

Wheat root diseases can seriously reduce yields and quality of wheat. 1,2,4-Triazole benzoyl arylamine derivatives previously showed good activities against some wheat root fungal pathogens. To further systematically disclose the structure-activity relationship, a series of benzoyl arylamines were designed and prepared. Their structures were characterized and fungicidal activities against Gaeumannomyces graminis var. tritici and Fusarium graminearum were evaluated. The results indicated that the structure of the N-heterocyclic group and the substituted group and their position on the benzamide scaffold had an important influence on the activities, as predicted. Finally, compound 18f was found to show excellent activities against G. graminis var. tritici, F. graminearum, Fusarium culmorum, Fusarium pseudograminearum, and Fusarium moniliforme with half-maximum effective concentrations of 0.002, 0.093, 0.011, 0.881, and 0.287 µg/mL, respectively. These results proposed that compound 18f deserved serious consideration as a novel fungicide candidate for the control of wheat root diseases.

Synaptopathy in Guinea Pigs Induced by Noise Mimicking Human Experience and Associated Changes in Auditory Signal Processing.

Noise induced synaptopathy (NIS) has been researched extensively since a large amount of synaptic loss without permanent threshold shift (PTS) was found in CBA mice after a brief noise exposure. However, efforts to translate these results to humans have met with little success-and might not be possible since noise exposure used in laboratory animals is generally different from what is experienced by human subjects in real life. An additional problem is a lack of morphological data and reliable functional methods to quantify loss of afferent synapses in humans. Based on evidence for disproportionate synaptic loss for auditory nerve fibers (ANFs) with low spontaneous rates (LSR), coding-in-noise deficits (CIND) have been speculated to be the major difficulty associated with NIS without PTS. However, no robust evidence for this is available in humans or animals. This has led to a re-examination of the role of LSR ANFs in signal coding in high-level noise. The fluctuation profile model has been proposed to support a role for high-SR ANFs in the coding of high-level noise in combination with efferent control of cochlear gain. This study aimed to induce NIS by a low-level, intermittent noise exposure mimicking what is experienced in human life and examined the impact of the NIS on temporal processing under masking. It also evaluated the role of temporal fluctuation in evoking efferent feedback and the effects of NIS on this feedback.