Exploring single-molecule interactions: heparin and FGF-1 proteins through solid-state nanopores.

Detection and characterization of protein-protein interactions are essential for many cellular processes, such as cell growth, tissue repair, drug delivery, and other physiological functions. In our research, we have utilized emerging solid-state nanopore sensing technology, which is highly sensitive to better understand heparin and fibroblast growth factor 1 (FGF-1) protein interactions at a single-molecule level without any modifications. Understanding the structure and behavior of heparin-FGF-1 complexes at the single-molecule level is very important. An abnormality in their formation can lead to life-threatening conditions like tumor growth, fibrosis, and neurological disorders. Using a controlled dielectric breakdown pore fabrication approach, we have characterized individual heparin and FGF-1 (one of the 22 known FGFs in humans) proteins through the fabrication of 17 ± 1 nm nanopores. Compared to heparin, the positively charged heparin-binding domains of some FGF-1 proteins translocationally react with the pore walls, giving rise to a distinguishable second peak with higher current blockade. Additionally, we have confirmed that the dynamic FGF-1 is stabilized upon binding with heparin-FGF-1 at the single-molecule level. The larger current blockades from the complexes relative to individual heparin and the FGF-1 recorded during the translocation ensure the binding of heparin-FGF-1 proteins, forming binding complexes with higher excluded volumes. Taken together, we demonstrate that solid-state nanopores can be employed to investigate the properties of individual proteins and their complex interactions, potentially paving the way for innovative medical therapies and advancements.

Transcriptomic analysis reveals prolonged neurodegeneration in the hippocampus of adult C57BL/6N mouse deafened by noise.

Introduction: Several studies have reported a significant correlation between noise-induced hearing loss and cognitive decline. However, comprehensive analyses of this relationship are rare. This study aimed to assess the influence of hearing impairment on cognitive functions by analyzing organ samples in the afferent auditory pathway of deafened mice using mRNA sequencing. Methods: We prepared 10 female 12-week-old C57BL/6N mice as the experimental and control groups in equal numbers. Mice in the experimental group were deafened with 120 dB sound pressure level (SPL) wideband noise for 2 h. Cochlea, auditory cortex, and hippocampus were obtained from all mice. After constructing cDNA libraries for the extracted RNA from the samples, we performed next-generation sequencing. Subsequently, we analyzed the results using gene ontologies (GOs) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway databases for differentially expressed genes (DEGs) of each organ. Results: Our results revealed 102, 89, and 176 DEGs for cochlea, auditory cortex, and hippocampus, respectively. We identified 294, 203, and 211 GOs; 10, 7, and 17 KEGG pathways in the cochlea, auditory cortex, and hippocampus, respectively. In the long term (12 weeks) from noise-induced hearing loss, GOs and KEGG pathways related to apoptosis or inflammation persisted more actively in the order of hippocampus, auditory cortex, and cochlea. Discussion: This implies that the neurodegenerative effects of noise exposure persist more longer time in the central regions.

Real-time monitoring of Ti(IV) metal ion binding of transferrin using a solid-state nanopore.

Transferrin, a central player in iron transport, has been recognized not only for its role in binding iron but also for its interaction with other metals, including titanium. This study employs solid-state nanopores to investigate the binding of titanium ions [Ti(IV)] to transferrin in a single-molecule and label-free manner. We demonstrate the novel application of solid-state nanopores for single-molecule discrimination between apo-transferrin (metal-free) and Ti(IV)-transferrin. Despite their similar sizes, Ti(IV)-transferrin exhibits a reduced current drop, attributed to differences in translocation times and filter characteristics. Single-molecule analysis reveals Ti(IV)-transferrin's enhanced stability and faster translocations due to its distinct conformational flexibility compared to apo-transferrin. Furthermore, our study showcases solid-state nanopores as real-time monitors of biochemical reactions, tracking the gradual conversion of apo-transferrin to Ti(IV)-transferrin upon the addition of titanium citrate. This work offers insights into Ti(IV) binding to transferrin, promising applications for single-molecule analysis and expanding our comprehension of metal-protein interactions at the molecular level.

Influence of Solute Size on Membrane Fouling during Polysaccharide Enrichment Using Dense Polymeric UF Membrane: Measurements and Mechanisms.

Fouling mechanisms associated with membrane-based polysaccharide enrichment were determined using a dense ultrafiltration (UF) membrane. Dextran with different molecular weights (MWs) was used as a surrogate for polysaccharides. The influence of dextran MW on fouling mechanisms was quantified using the Hermia model. Flux data obtained with different dextran MWs and filtration cycles were plotted to quantify the more appropriate fouling mechanisms among complete pore blocking, standard pore blocking, intermediate pore blocking, and cake filtration. For 100,000 Da dextran, all four mechanisms contributed to the initial fouling. As the filtration progressed, the dominant fouling mechanism appeared to be cake filtration with a regression coefficient (R2) of approximately 0.9519. For 10,000 Da, the R2 value for cake filtration was about 0.8767 in the initial filtration. Then, the R2 value gradually decreased as the filtration progressed. For 6000 Da, the R2 values of the four mechanisms were very low in the initial filtration. However, as the filtration progressed, the R2 value for cake filtration reached 0.9057. These results clearly show that the fouling mechanism of dense UF membranes during polysaccharide enrichment can be quantified. In addition, it was confirmed that the dominant fouling mechanism can change with the size of the polysaccharide and the duration of filtration.

Comparison of hearing outcomes in patients with congenital aural atresia managed with canaloplasty and bone conduction hearing devices.

BACKGROUND: Treatment options for congenital aural atresia (CAA) include canaloplasty and implantation of an osseointegrated bone conduction device (OBCD). Few studies have compared hearing outcomes in these two treatment methods. OBJECTIVES: Hearing outcomes and revision surgery rates were compared in CAA patients managed by canaloplasty and surgically implanted OBCD. METHODS: This study retrospectively analyzed 36 patients with CAA at a single institution. The same surgeon performed canaloplasty on 23 patients. Hearing outcomes before surgery as well as 3 and 6 months after surgery were compared to those of 13 patients with OBCD implantation. RESULTS: Postoperative hearing outcomes were better in the OBCD group, but the difference was not statistically significant. At 6-month follow-up, the hearing thresholds in the canaloplasty and OBCD group were 38.6 ± 21.4 and 31.9 ± 6.4 dB, respectively. The success rates 6 months after surgery were 75.0% in the canaloplasty group and 100% in the OBCD group. Two out of 23 patients in the canaloplasty group and 7 out of 13 patients in the OBCD group underwent revision surgery. CONCLUSION: In terms of hearing, the outcome was better with the OBCD compared to canaloplasty. Canaloplasty may be an alternative option in patients who refuse OBCD implantation.

Applicability of a Combined DAF-MF Process to Respond to Changes in Reservoir Water Quality through a Two-Year Pilot Plant Operation.

The optimal operating conditions of a combined dissolved air flotation (DAF)-microfiltration (MF) process to respond to changes in raw water quality were investigated by operating a pilot plant for two years. Without DAF pre-treatment (i.e., MF alone), MF operated stably with a transmembrane pressure (TMP) increase of 0.24 kPa/d when the turbidity of raw water was low and stable (max. 13.4 NTU). However, as the raw water quality deteriorated (max. 76.9 NTU), the rate of TMP increase reached 43.5 kPa/d. When DAF pre-treatment was applied (i.e., the combined DAF-MF process), the MF process operated somewhat stably; however, the rate of TMP increase was relatively high (i.e., 0.64 kPa/d). Residual coagulants and small flocs were not efficiently separated by the DAF process, exacerbating membrane fouling. Based on the particle count analysis of the DAF effluent, the DAF process was optimised based on the coagulant dose and hydraulic loading rate. After optimisation, the rate of TMP increase for the MF process stabilised at 0.17 kPa/d. This study demonstrates that the combined DAF-MF process responded well to substantial changes in raw water quality. In addition, it was suggested that the DAF process must be optimised to avoid excessive membrane fouling.

Outcome of cochlear implantation in the worse ear of post-lingual asymmetric hearing loss: elucidation of prognostic markers.

BACKGROUND: Specific correlations between the outcomes of cochlear implantation (CI) and hearing thresholds of the both ears in post-lingual asymmetric hearing loss (AHL) patients were not clear. AIMS/OBJECTIVES: To identify the variables influencing the outcome of CI in post-lingual AHL patients. METHOD: We included 18 adult subjects who had CI in the worse ear due to post-lingual AHL with average hearing asymmetry of 36 dB. Speech perception scores were evaluated in the sound field with hearing aid on the better ear before CI, and with the cochlear implant in the worse ear at 3, 6, and 12 months after CI switch-on. RESULTS: Average increases in phonetically balanced word score, spondee word score, and everyday sentence score at 12 months from CI switch-on compared with those before CI were 38.9%p, 46.2%p, and 52.4%p, respectively. Multiple linear regression analysis showed that speech perception scores were negatively influenced by age at implantation and hearing threshold difference of both ears (HTD-Both) itself, rather than the worse or better ear hearing thresholds. CONCLUSIONS AND SIGNIFICANCE: Post-lingual AHL subjects with high average hearing asymmetry can benefit from CI in the worse ear, while CI outcomes can be adversely influenced by HTD-Both and age at implantation both in the short- and long-term follow-up.

Clogged water bridges for fog harvesting.

Capillary water bridges clogged in the holes of mesh-type fog harvesters have previously been considered only as a drawback because they decrease fog-harvesting yield by hindering airflow in front of the clogged mesh in the usual wind conditions. In this study, we show that the role of a clogged water bridge may not be entirely negative and can contribute to increased fog harvesting by increasing the effective shade coefficient in a special condition with high fog inertia. As the fog speed close to the mesh or the plate increases, clogged mesh as well as the impermeable solid plate are found to produce high fog-harvesting efficiency owing to the high inertia of fog particles that impact the blocked wall. For fast fog speeds (∼4 m s-1) near the mesh, our results show that the fog-harvesting efficiency is proportional to the effective shade coefficient because fog flow circumventing the mesh is limited owing to high fog inertia. We analyzed the clogging effect on fog-harvesting performance by distinguishing between self-clogging and non-self-clogging patterns based on the water bridge stability clogged in mesh holes.

Associations between Particulate Matter and Otitis Media in Children: A Meta-Analysis.

Particulate matter (PM), a primary component of air pollution, is a suspected risk factor for the development of otitis media (OM). However, the results of studies on the potential correlation between an increase in the concentration of PM and risk of developing OM are inconsistent. To better characterize this potential association, a meta-analysis of studies indexed in three global databases (PubMed, EMBASE, and The Cochrane Library) was conducted. These databases were systematically screened for observational studies of PM concentration and the development of OM from the time of their inception to 31 March 2020. Following these searches, 12 articles were analyzed using pooled odds ratios generated from random-effects models to test for an association between an increased concentration of PM and the risk of developing OM. The data were analyzed separately according to the size of particulate matter as PM2.5 and PM10. The pooled odds ratios for each 10 µg/m3 increase in PM2.5 and PM10 concentration were 1.032 (95% confidence interval (CI), 1.005-1.060) and 1.010 (95% CI, 1.008-1.012), respectively. Specifically, the pooled odds ratios were significant within the short-term studies (PM measured within 1 week of the development of OM), as 1.024 (95% CI, 1.008-1.040) for PM2.5 concentration and 1.010 (95% CI, 1.008-1.012) for PM10 concentration. They were significant for children under 2 years of age with pooled odds ratios of 1.426 (95% CI, 1.278-1.519) for an increase in the concentration of PM2.5. The incidence of OM was not correlated with the concentration of PM, but was correlated with an increase in the concentration of PM. In conclusion, an increase in the concentration of PM2.5 is more closely associated with the development of OM compared with an increase in the concentration of PM10; this influence is more substantial in shorter-term studies and for younger children.

Clinical Characteristics of Patients with Cochlear Fistulas Caused by Chronic Otitis Media with Cholesteatoma.

OBJECTIVES: To analyze the clinical characteristics of cochlear fistulas (CFs) and propose a new fistula classification system with regard to the cochlea. MATERIALS AND METHODS: A retrospective chart review was conducted between January 2008 and December 2015 to identify patients who had undergone surgery for cholesteatoma with an associated CF. The following data were collected: preoperative symptoms, findings of temporal bone computed tomography (TBCT), fistula stage, cholesteatoma classification, surgical technique, and pre- and postoperative pure-tone audiometry. RESULTS: We analyzed a total of 159 patients, out of which 9 (5.7%) were diagnosed with a CF. The average duration of the chronic otitis media was 19.8 years. Cholesteatomas that induced CF rarely existed in the nonaggressive state; recurrent otorrhea was observed in all but one of our subjects. All the patients with CF had a distinct origin of cholesteatoma that developed from the retraction of posterior pars tensa; further, 88.9% cholesteatomas extended to and filled the sinus tympani. Preoperative audiometry revealed total hearing loss in 4 (44.4%) patients. Further, five patients with residual hearing before surgery had stage I fistulas, and the bone conduction thresholds remained stable after surgery. CONCLUSION: Cochlear fistulas were often detected in patients with (1) a history of chronic otitis media (exceeding 10 years), (2) frequently recurring otorrhea, and (3) pars tensa cholesteatomas that extended to the posterior mesotympanum and filled the sinus tympani. Such patients can suffer from potentially severe and irreparable sensorineural hearing loss.

Outcomes of Peptide Vaccine GV1001 Treatment in a Murine Model of Acute Noise-Induced Hearing Loss.

Noise-induced hearing loss (NIHL) is primarily caused by damage to cochlear hair cells, associated with synaptopathy. The novel cell-penetrating peptide GV1001, an antitumor agent, also has antioxidant and anti-inflammatory effects, and is otoprotective in a murine model of kanamycin-induced ototoxicity. Here, we explored whether GV1001 attenuated NIHL, and the underlying mechanism at play. We established an NIHL model by exposing 4- to 6-week-old C57/BL6 mice to white noise at 120 dB SPL for 2 h, resulting in a significant permanent threshold shift (PTS). We then subcutaneously injected saline (control), GV1001, or dexamethasone immediately after cessation of PTS-noise exposure and evaluated the threshold shifts, structural damages to outer hair cells (OHCs), and ribbon synapses. We also verified whether GV1001 attenuates oxidative stress at the level of lipid peroxidation or protein nitration in OHCs 1 h after exposure to white noise at 120 dB SPL. GV1001-treated mice exhibited significantly less hearing threshold shifts over 2 weeks and preserved OHCs and ribbon synapses compared with controls. Similarly, dexamethasone-treated mice showed comparable protection against NIHL. Importantly, GV1001 markedly attenuated oxidative stress in OHCs. Our findings suggest that GV1001 may protect against NIHL by lowering oxidative stress and may serve as preventive or adjuvant treatment.

Natural Course of Unilateral Vocal Fold Paralysis and Optimal Timing of Permanent Treatment.

Importance: Permanent surgical treatment for unilateral vocal fold paralysis (UVFP) should be performed when further neural recovery is improbable. Conservative delay of the surgical procedure may cause unnecessary deterioration of the patient's quality of life. Knowledge of the natural course of UVFP is important for better management and counseling. Objective: To evaluate the natural course of UVFP, focusing on the recovery time according to the injury level to assess the optimal timing for permanent surgical intervention. Design, Setting, and Participants: This retrospective case series enrolled 1264 patients with UVFP who visited the voice clinic of Seoul National University Hospital, Seoul, Korea, from November 1, 2005, through December 31, 2016. Medical records and stroboscopic video images were reviewed to obtain data on demographic characteristics, vocal fold movement, onset and recovery time, follow-up duration, and cause. Cases of UVFP were classified into 5 groups based on the location of injury: distal to the thyroid level, thyroid level, esophagus and mediastinum level, heart and lung level, and proximal to the thorax level. Data analysis was performed from January 23, 2018, to May 21, 2018. Main Outcomes and Measures: Recovery of vocal fold movement defined as more than vocal fold twitching confirmed by stroboscopy video images, estimated injury level, and start time of recovery. The recovery time was analyzed according to age, sex, paralytic side, and 5 injury levels. Results: Of 1264 eligible patients with UVFP (655 [51.8%] male; median age, 56 years [range, 1-90 years]), 208 had evidence of recovery with the recovery time relatively accurate. The maximum recovery time for the group with distal to the thyroid-level injury was 120 days; the group with thyroid-level injury, 157 days; the group with esophagus and mediastinum-level injury, 244 days; the group with heart and lung-level injury, 328 days; and the group with proximal to the thorax-level injury, 333 days with the exception of 1 outlier value (482 days). Recovery time did not differ according to age, sex, or paralytic side. As distance between the vocal fold and injury level increased, the maximum recovery time increased, plateauing at 1 year. Among the patients who showed recovery of the vocal fold movement, most patients with injuries distal to or at the level of the thyroid recovered within 6 months, whereas those with injury more distant from the vocal fold recovered within approximately 1 year. Conclusions and Relevance: A linear association between injury level and maximum recovery time was observed. The findings suggest that the decision to proceed with permanent phonosurgical treatment should be based on the level of injury associated with UVFP.

Nasopharyngeal Width and Its Association With Sleep-Disordered Breathing Symptoms in Children.

OBJECTIVES: Although adenotonsillar hypertrophy is the main cause of sleep-disordered breathing in children, surrounding anatomic factors, such as the width of the nasopharynx, can affect upper airway patency. However, there have been no reports of the association of nasopharyngeal width with sleep-disordered breathing in children. This study was undertaken to measure nasopharyngeal width in children undergoing adenotonsillectomy for sleep-disordered breathing and to investigate the clinical implications of this factor. METHODS: This was a retrospective study with a follow-up period of 1 year, performed at a tertiary referral center. We reviewed the operative records of children who underwent adenotonsillectomy at our center for symptoms of sleepdisordered breathing, such as snoring, apnea, and mouth breathing. The nasopharyngeal width was measured immediately before adenotonsillectomy, which was performed under general anesthesia with a microscopy-assisted mirror view. Adenotonsillar hypertrophy was graded on a four-point scale, and symptoms of sleep-disordered breathing were evaluated by using the Korean version of the Obstructive Sleep Apnea-18 questionnaire before and after surgery. The relationships between the average nasopharyngeal width and patient age and sex, adenotonsillar hypertrophy, and the Korean version of the Obstructive Sleep Apnea-18 score were analyzed. RESULTS: The study included 549 children (343 boys) with a mean age of 6.0 years (range, 2 to 11 years). The average nasopharyngeal width was 11.9 mm (range, 7.0 to 18.0 mm) and increased with age (range, 11.2 to 13.3; ß=0.264; P< 0.001). At 1 year after surgery, children with a greater nasopharyngeal width at the time of surgery exhibited additional improvements in symptoms of obstruction relative to those at 1 month after surgery. CONCLUSION: The average nasopharyngeal width in children is approximately 11.9 mm and exhibits a slight increase with age. The width of the nasopharynx may be a factor associated with the degree of improvement in symptoms of sleepdisordered breathing after adenotonsillectomy.

Involvement of the Internal Auditory Canal in Subjects With Cochlear Otosclerosis: A Less Acknowledged Third Window That Affects Surgical Outcome.

OBJECTIVE: To investigate the effects of cavitating lesions involving the internal auditory canal (IAC) in subjects with cochlear otosclerosis with regard to poststapedotomy hearing outcome. STUDY DESIGN: Retrospective study. SETTING: Tertiary referral center. PATIENTS: A retrospective chart review of 134 subjects with otosclerosis treated from January 2011 to June 2017 at Seoul National University Bundang Hospital was conducted. Sixteen subjects (23 ears) with temporal bone computed tomography (TBCT)-confirmed cochlear otosclerosis who underwent stapedotomy were included in the study. MAIN OUTCOME MEASURES: Pure tone audiometry (PTA) (i.e., air and bone conduction; AC and BC, respectively) thresholds and air-bone gap (ABG), measured at 6 months postoperatively were compared between cochlear otosclerosis with and without IAC involvement (IAC group and non-IAC group, respectively). RESULTS: A total of 14 of 23 ears showed involvement of the IAC. There were no significant differences in age, side of otosclerosis, or preoperative hearing threshold between the two groups. The mean postoperative AC and BC thresholds and ABG of the IAC group were significantly poorer (45.7 dB, 33.8 dB, and 11.8 dB, respectively) than those of the nonIAC group (24.1 dB, 20.0 dB, and 4.1 dB, respectively). CONCLUSIONS: Cochlear otosclerosis with cavitating lesions involving the IAC showed significantly poorer postoperative audiological outcomes than those without any cavitating lesion. Cavitation extending to the IAC may act as a third window providing a route for sound energy shunting, and thus precluding successful hearing outcome in some subjects with cavitating otosclerosis after stapedotomy.

Cochlear Implantation in Postlingually Deaf Adults is Time-sensitive Towards Positive Outcome: Prediction using Advanced Machine Learning Techniques.

Given our aging society and the prevalence of age-related hearing loss that often develops during adulthood, hearing loss is a common public health issue affecting almost all older adults. Moderate-to-moderately severe hearing loss can usually be corrected with hearing aids; however, severe-to-profound hearing loss often requires a cochlear implant (CI). However, post-operative CI results vary, and the performance of the previous prediction models is limited, indicating that a new approach is needed. For postlingually deaf adults (n de120) who received CI with full insertion, we predicted CI outcomes using a Random-Forest Regression (RFR) model and investigated the effect of preoperative factors on CI outcomes. Postoperative word recognition scores (WRS) served as the dependent variable to predict. Predictors included duration of deafness (DoD), age at CI operation (ageCI), duration of hearing-aid use (DoHA), preoperative hearing threshold and sentence recognition score. Prediction accuracy was evaluated using mean absolute error (MAE) and Pearson's correlation coefficient r between the true WRS and predicted WRS. The fitting using a linear model resulted in prediction of WRS with r = 0.7 and MAE = 15.6 ± 9. RFR outperformed the linear model (r = 0.96, MAE = 6.1 ± 4.7, p < 0.00001). Cross-hospital data validation showed reliable performance using RFR (r = 0.91, MAE = 9.6 ± 5.2). The contribution of DoD to prediction was the highest (MAE increase when omitted: 14.8), followed by ageCI (8.9) and DoHA (7.5). After CI, patients with DoD < 10 years presented better WRSs and smaller variations (p < 0.01) than those with longer DoD. Better WRS was also explained by younger age at CI and longer-term DoHA. Machine learning demonstrated a robust prediction performance for CI outcomes in postlingually deaf adults across different institutes, providing a reference value for counseling patients considering CI. Health care providers should be aware that the patients with severe-to-profound hearing loss who cannot have benefit from hearing aids need to proceed with CI as soon as possible and should continue using hearing aids until after CI operation.

Association of Coffee Consumption with Hearing and Tinnitus Based on a National Population-Based Survey.

Coffee is the one of the most common beverages worldwide and has received considerable attention for its beneficial health effects. However, the association of coffee with hearing and tinnitus has not been well studied. The aim of this study was to investigate the association of coffee with hearing and tinnitus based on a national population-based survey. We evaluated hearing and tinnitus data from the 2009⁻2012 Korean National Health and Nutrition Examination Survey and their relationship with a coffee consumption survey. All patients underwent a medical interview, physical examination, hearing test, tinnitus questionnaire and nutrition examination. Multivariable logistic regression models were used to examine the associations between coffee and hearing loss or tinnitus. We evaluated 13,448 participants (≥19 years) participants. The frequency of coffee consumption had a statistically significant inverse correlation with bilateral hearing loss in the 40⁻64 years age group. Daily coffee consumers had 50⁻70% less hearing loss than rare coffee consumers, which tended to be a dose-dependent relationship. In addition, the frequency of coffee consumption had an inverse correlation with tinnitus in the 19⁻64 years age group but its association was related with hearing. Brewed coffee had more of an association than instant or canned coffee in the 40⁻64 years age group. These results suggest a protective effect of coffee on hearing loss and tinnitus.

Shaping Rolling Circle Amplification Products into DNA Nanoparticles by Incorporation of Modified Nucleotides and Their Application to In Vitro and In Vivo Delivery of a Photosensitizer.

Rolling circle amplification (RCA) is a robust way to generate DNA constructs, which are promising materials for biomedical applications including drug delivery because of their high biocompatibility. To be employed as a drug delivery platform, however, the DNA materials produced by RCA need to be shaped into nanoparticles that display both high cellular uptake efficiency and nuclease resistance. Here, we showed that the DNA nanoparticles (DNPs) can be prepared with RCA and modified nucleotides that have side-chains appended on the nucleobase are capable of interacting with the DNA strands of the resulting RCA products. The incorporation of the modified nucleotides improved cellular uptake efficiency and nuclease resistance of the DNPs. We also demonstrated that these DNPs could be employed as carriers for the delivery of a photosensitizer into cancer cells to achieve photodynamic therapy upon irradiation at both the in vitro and in vivo levels.

Feasibility Study on a Segmented Ferrofluid Flow Linear Generator for Increasing the Time-Varying Magnetic Flux.

Nanoparticles and nanofluids have been implemented in energy harvesting devices, and energy harvesting based on magnetic nanofluid flow was recently achieved by using a layer-built magnet and micro-bubble injection to induce a voltage on the order of 10-1 mV. However, this is not yet suitable for some commercial purpose. In order to further increase the amount of electric voltage and current from this energy harvesting the air bubbles must be segmented in the base fluid, and the magnetic flux of the segmented flow should be materially altered over time. The focus of this research is on the development of a segmented ferrofluid flow linear generator that would scavenge electrical power from waste heat. Experiments were conducted to obtain the induced voltage, which was generated by moving a ferrofluid-filled capsule inside a multi-turn coil. Computations were then performed to explain the fundamental physical basis of the motion of the segmented flow of the ferrofluids and the air-layers.

Numerical Simulation on the Induced Voltage Across the Coil Terminal by the Segmented Flow of Ferrofluid and Air-Layer.

Nanoparticles and nanofluids have been implemented in energy harvesting devices, and energy harvesting based on magnetic nanofluid flow was recently achieved by using a layer-built magnet and microbubble injection to induce a voltage on the order of 10-1 mV. However, this is not yet suitable for some commercial purpose. The air bubbles must be segmented in the base fluid, and the magnetic flux of the ferrofluids should change over time to increase the amount of electric voltage and current from energy harvesting. In this study, we proposed a novel technique to achieve segmented flow of the ferrofluids and the air layers. This segmented ferrofluid flow linear generator can increase the magnitude of the induced voltage from the energy harvesting system. In our experiments, a ferrofluid-filled capsule produced time-dependent changes in the magnetic flux through a multi-turn coil, and the induced voltage was generated on the order of about 101 mV at a low frequency of 2 Hz. A finite element analysis was used to describe the time-dependent change of the magnetic flux through the coil according to the motion of the segmented flow of the ferrofluid and the air-layer, and the induced voltage was generated to the order of 102 mV at a high frequency of 12.5 Hz.

Corrigendum: A Quantitative Electroencephalography Study on Cochlear Implant-Induced Cortical Changes in Single-Sided Deafness with Tinnitus.

[This corrects the article on p. 210 in vol. 11, PMID: 28572760.].