Evaluation of ocular and cervical vestibular evoked myogenic potentials in a conductive hearing loss model

Objective: To investigate the effects of conductive hearing loss(CHL) on vestibular evoked myogenic potentials(VEMPs) using a simulated CHL model, and to provide the basis for future studies.Methods: Twenty-one healthy subjects were recruited in this study. We measured ocular VEMPs(o VEMPs) and cervical VEMPs(c VEMPs) in these subjects by air-conduction sound(ACS) stimulation. CHL was simulated later by blocking the right external auditory canal with a soundproof earplug to evaluate its impacts on VEMPs. Subjects' responses before simulated CHL served as the control, and were compared to their responses following simulated CHL.Results: o VEMPs following simulated CHL showed decreased response rate, elevated thresholds, attenuated amplitudes and prolonged N1 latencies compared with those before simulated CHL, and the differences were statistically significant. Similarly, c VEMPs following simulated CHL also showed decreased response rate, elevated thresholds and attenuated amplitudes, with prolonged P1 latencies compared with those before simulated CHL, although only differences in response rate, threshold and amplitude were significant.Conclusions: Conductive hearing loss affects the response rate and other response parameters in o VEMPs and c VEMPs.

IC Pattern Based Power Factor Maximization Model for Improved Power Stabilization

The voltagefluctuation in electric circuits has been identified as key issue in different electric systems.As the usage of electricity growing in rapid way,there exist higherfluctuations in powerflow.To maintain theflow or stabi-lity of power in any electric circuit,there are many circuit models are discussed in literature.However,they suffer to maintain the output voltage and not capable of maintaining power stability.To improve the performance in power stabilization,an efficient IC pattern based power factor maximization model(ICPFMM)in this article.The model is focused on improving the power stability with the use of IC(Inductor and Conductor)towards identifying most efficient circuit for the current duty cycle according to the input voltage,voltage in capacitor and output voltage required.The model with boost converter diverts the incoming voltage through number of conductors and inductors.By triggering specific inductor,a specific capacitor gets charged and a particular circuit gets on.The model maintains num-ber of IC(Inductor and Conductor)patterns through which the powerflow occurs.According to that,the pattern available,the mofset controls the level of power to be regulated through any circuit.From the pattern,the model computes the Cir-cuits Switching Loss and Circuits Conduction Loss for various circuits.Accord-ing to the input voltage,the model estimates Circuit Power Stabilization Support(CPSS)according to the voltage available in any capacitor and input voltage.Using the value of CPSS,the model trigger optimal number of circuits to maintain voltage stability.In this approach,more than one circuit has been triggered to maintain output voltage and to get charged.The proposed model not only main-tains power stability but also reduces the wastage in voltage which is not utilized.The proposed model improves the performance in voltage stability with less switching loss.

Hearing Assessment among Sudanese Rheumatoid Arthritis Patients versus Non-Rheumatoid Arthritis Individuals

Background: Rheumatoid arthritis (RA) disease is one of the most common chronic autoimmune diseases that affect many body systems including the auditory system. Objectives: To assess hearing thresholds and to ascertain types of hearing loss among Sudanese rheumatoid arthritis patients attending rheumatology clinic in Omdurman military hospital and matching them with non-rheumatoid arthritis subjects. Methodology: This descriptive and analytic (comparative) hospital based cross sectional study conducted from October 2020 to April 2021 which include 66 RA patients with age range (21 - 60 years) matched with 41 non-rheumatoid arthritis group sharing same characteristics (nation, gender and age). Pure tone audiometry, tympanometry and acoustic reflexes were done for all RA patients and matched groups. Statistical analysis of the data was carried out using the association and correlation tests for associations and t-test for independent samples. Results: Thirty-six (54.5%) of RA patients had hearing impairment versus 9 (22%) non-RA in PTA test. Twenty-four RA cases (36.3%) showed asymmetrical hearing threshold and graph in PTA between right and left ears. Thirty-four (51.5%) right and 36 (54.5%) left ears were normal degree followed by 23 (34.8%) in the right and 24 (36.4%) in the left ears were mild degree hearing loss. Among hearing impaired RA patients;20 right ears (62.5%) and 19 left ears (65.5%) had sensorineural hearing loss (SNHL), conductive hearing loss 11 (34.4%) right ears and 9 (31%) left ears. Mixed HL was in 1 right ear (3.1%) and 1 left ear (3.5%). The most common degree of SNHL type was mild in (75%) and (78.9%) in right and left ears respectively, moderate and moderate severe were (20%) in the right and (15.7%) in the left ears. Fifty-eight right ears (87.9%) and 56 left ears (84.8%) had type A tympanogram while 7 (10.6%) right ears and 9 left ears (13.6%) were type As tympanogram, one right and one left ears had type Ad tympanogram. Acoustic reflex was impaired in 17 right ears and 17 left ears (25.8% for both). There were significant statistical differences in most of the specific frequency means between the study group and non-rheumatoid group in the right and left ears p-value 0.05). Also there was no significant statistical association between anti-rheumatic drugs used and hearing threshold of RA patients (p-value > 0.05). Conclusion: Hearing impairment especially sensorineural type is common in Sudanese rheumatoid arthritis patients. Conductive hearing loss is less common and most likely due to ossicles diarthrodial joint stiffness. No influence of the disease activity or used anti-rheumatic drugs on hearing threshold of the RA patients was detected in this study.

Middle ear osteoma causing Eustachian tube obstruction:A case report and literature review

Middle ear osteoma is an extremely rare benign tumor of the middle ear.Due to its very slow growth rate and benign nature,osteoma of the middle ear can be found incidentally without causing any symptoms.The most common clinical signs are conductive hearing loss,the sense of fullness in the ear,tinnitus,and otorrhea.Small-sized osteomas can be misdiagnosed as otosclerosis without showing any signs other than conductive hearing loss.When the mass becomes very large,and symptoms caused by the tumor increase,treatment also becomes difficult.In this paper,we report a case of middle ear osteoma causing conductive hearing loss and effusion due to the effect of pressure on the middle ear ossicles and the Eustachian tube.We also present a review of the pertinent literature.

Hierarchical engineering of CoNi@Air@C/SiO_(2)@Polypyrrole multicomponent nanocubes to improve the dielectric loss capability and magnetic-dielectric synergy

Impedance matching characteristics and loss capabilities including magnetic loss,polarization loss and conduction loss are critical factors to improve microwave absorption performances(MAPs).To elevate these aspects,herein,yolk-shell structured CoNi@Air@C/SiO_(2)@Polypyrrole(PPy)magnetic multicomponent nanocubes(MCNCs)were designed and successfully fabricated in high efficiency through a continuous co-precipitation route,classical Stöber method,thermal treatment and polymerization reaction.The obtained results indicated that the formation of SiO_(2) effectively stabilized the cubic geometrical morphology and yolk-shell structure during the high-temperature pyrolysis process.The introduction of PPy greatly boosted their polarization loss and conductive loss capabilities.Therefore,the as-prepared yolkshell structured CoNi@Air@C/SiO_(2)@PPy MCNCs presented superior MAPs compared to CoNi@Air@C/SiO_(2) MCNCs.Furthermore,by regulating the content of PPy,the obtained CoNi@Air@C/SiO_(2)@PPy MCNCs displayed tunable and excellent comprehensive MAPs in terms of strong absorption capabilities,broad frequency bandwidths and thin matching thicknesses,which could be ascribed to the unique structure and excellent magnetic-dielectric synergistic effect.Therefore,our findings provided an alternative pathway to effectively utilize the magnetic-dielectric synergy and loss capabilities for the developing yolk-shell structured magnetic MCNCs as the strong wideband microwave absorbers.

Top-down strategy for bamboo lignocellulose-derived carbon heterostructure with enhanced electromagnetic wave dissipation

Biomass-derived residue carbonization has been an important issue for"carbon fixation"and"zero emission",and the carbonized products have multiple application potentials.However,there have been no specific research to study the differences in macro-and micro-morphology,electrical properties and many other aspects of the products obtained from carbonization of pure cellulose,pure lignin or their complex,lignocellulose.In this work,lignocellulose with cellulose to lignin mass ratio of 10:1 is obtained using p-toluenesulfonic acid hydrolysis followed by homogenization process at a controlled condition.Then,carbon heterostructure with fibers and sheets(CH-10)are obtained by pyrolysis at 1500℃.Detailed results imply that the fiber-like carbon structure possesses high crystallinity and low defect density,coming from carbonization of the cellulose content in lignocellulose(LC)nanofibers.Correspondingly,the graphite-like carbon sheet with high defect density and low crystallinity comes from carbonization of the lignin content in LCs.Further investigation indicates CH-10 possesses enhanced polarization and moderate impedance matching which makes it an ideal candidate for electromagnetic wave(EMW)absorption.CH-10 exhibits an excellent EMW absorption performance with a minimum RL value of-50.05 dB and a broadest absorption bandwidth of 4.16 GHz at a coating thickness as thin as 1.3 mm.

Malleostapedotomy for otosclerosis,our experience of nitinol piston on twelve patients

Objective:Malleostapedotomy allows to completely by-pass the incus in otosclerosis surgery.Recently its use has been rivaled by hydroxyapatite cement for cases of mild and moderate necrosis of the incus.However,it remains gold standard for cases of extensive necrosis,incus dislocation,or epitympanic fixation.Modern heat-crimping pistons make surgery easier and safer.This study focuses on our experience with this technique.Methods:Retrospective analysis of patient’s files and pre-and post-operative audiograms,for cases of surgically treated otosclerosis with malleostapedotomy.Results:Twelve patients underwent malleostapedotomy for otosclerosis between 2011 and 2019.Amongst them there were 10 revision surgeries and 2 primary cases.75%had incus long-process necrosis,17%had epitympanic fixation and one had a history of incus transposition.Nine patients(75%)had closure of air-bone gap(ABG)of<10 dB(p<0.001)and 11(92%)had a threshold of 20 dB(p<0.001).Mean pre-operative ABG was 31 dB(15 dBe55 dB),and mean post-operative ABG was 7 dB(0 dBe21 dB;p<0.001).There was no sensorineural hearing loss nor any other post-operative complication.Conclusions:Malleostapedotomy is a safe and reliable technique,allowing an ABG closure comparable to conventional incus to vestibule prosthesis.It remains the preferred technique whenever the incus cannot be used.

Achieving ultra-broadband electromagnetic absorption of Ag regulated hollow Ag/CuO@CuS through balancing conduction loss and impedance matching

Excellent impedance matching and high conduction loss are important factors for the preparation of high-performance electromagnetic wave(EMW)absorbing materials,but these two properties are of-ten contradictory.In this work,three absorbers with unique hollow structures,H-Ag/CuO@CuS,H-O-Ag/CuO@CuS,and H-P-Ag/CuO@CuS,are designed and synthesized by adopting hollow CuO@CuS with double shell as carrier and silver nitrate as the structural regulator.The more voids coming from hol-low structures,window-opened structures,and stacked pores improve the impedance matching of these absorbers,and the introduction of elemental Ag effectively regulates the conduction loss.Therefore,a balance between impedance matching and conduction loss is achieved to improve the reflection loss(RL)value and broadens the absorbing band of the absorbers.In comparison to H-Ag/CuO@CuS and H-O-Ag/CuO@CuS(hollow structure with open window)in which elemental Ag is uniformly dispersed in the CuO layer,H-P-Ag/CuO@CuS exhibits more excellent EMW absorption performance due to more voids and an optimized conductive network arising from Ag/CuO pieces distributed between the hol-low Ag/CuO@CuS particles and Ag distributed in the CuS layer.When the thickness is 2.3 mm,H-P-Ag/CuO@CuS provides an ultra-wide electromagnetic absorption band of 8.56 GHz(9.44-18 GHz),in which the RL<-10 dB and the minimum reflection loss of-41 dB.

Simultaneous optimization of conduction and polarization losses in CNT@NiCo compounds for superior electromagnetic wave absorption

Polarization and conduction losses are the two most crucial dielectric loss mechanisms for carbon-based composites,but their synergistic effects in different frequency bands need to be further revealed.More importantly,for polarization and conduction losses,the strengthening of one party always comes at the expense of the other,which inevitably limits the overall performance of the absorbers.Herein,we have developed a composite of CNT and NiCo hybrid particles via a scalable wet chemical process and an-nealing method.Through the adjustment of the precursor and the annealing temperature,the conduction and polarization losses of the composite are optimized simultaneously.The optimized samples achieved the full absorption of the X and Ku bands under conditions of low filling rate and thin thickness.Further theoretical and experimental studies have revealed conduction loss and polarization loss laws at different frequency ranges.The synergistic effect of conductive loss and magnetic loss in the low-frequency region ensures that the sample exhibits high microwave dissipation performance.However,in the medium and high-frequency part,the magnetic loss can be almost ignored and the timely replenishment of polar-ization loss keeps the wave-absorbing performance at a high level.The excellent multi-band absorption characteristics make the as-obtained absorbers meet the needs of future applications.

Unique electromagnetic wave absorber for three-dimensional framework engineering with copious heterostructures

In order to obtain high-performance electromagnetic wave absorbers,the adjustment of structure and components is essential.Based on the above requirements,this system forms a three-dimensional frame structure consisting of MXene and transition metal oxides(TMOs)through efficient electrostatic self-assembly.This three-dimensional network structure has rich heterojunction structures,which can cause a large amount of interface polarization and conduction losses in incident electromagnetic waves.Hollow structures cause multiple reflections and scattering of electromagnetic waves,which is also an important reason for further increasing electromagnetic wave losses.When the doping ratio is 1:1,the system has the best impedance matching,the maximum effective absorption bandwidth(EAB max)can reach 5.12 GHz at 1.7 mm,and the minimum reflection loss(RL_(min))is-50.30 dB at 1.8 mm.This provides a reference for the subsequent formation of 2D-MXene materials into 3D materials.

Flexible regulation engineering of titanium nitride nanofibrous membranes for efficient electromagnetic microwave absorption in wide temperature spectrum

Simultaneous development of well impedance matching and strong loss capability has become a mainstream method for achieving outstanding electromagnetic microwave absorption(EMWA)performances over wide temperature range.However,it is difficult to pursue both due to the mutual restraint of relationship between impedance matching and loss capability about temperature.Here,we propose a flexible regulation engineering of titanium nitride(TiN)nanofibrous membranes(NMs,TNMs),which could be distributed uniformly in the polydimethylsiloxane(PDMS)matrix and contributed to the formation of abundant local conductive networks,generating the local conductive loss and enhancing the loss ability of EMWs.Moreover,when the TNMs are used as functional units and dispersed in the matrix,the corresponding composites exhibit an outstanding anti-reflection effect on microwaves.As hoped,under the precondition of good impedance matching,local conductive loss and polarization loss together improve the loss capacity at room temperature,and polarization loss can compensate the local conductive loss to acquire effective dielectric response at elevated temperature.Benefiting from the reasonably synergistic loss ability caused by flexible regulation engineering,the corresponding composites exhibit the perfect EMWA performances in a wide temperature range from 298 to 573 K.This work not only elaborates the ponderable insights of independent membrane in the composition-structure-function connection,but also provides a feasible tactic for resolving coexistence of well impedance matching and strong loss capability issues in wide temperature spectrum.

Fast valve power loss evaluation method for modular multi-level converter operating at high-frequency

There is no common accepted way for calculating the valve power loss of modular multilevel converter(MMC).Valve power loss estimation based on analytical calculation is inaccurate to address the switching power loss and valve power loss estimation based on detailed electro-magnetic simulation is of low speed.To solve this problem,a method of valve power loss estimation based on the detailed equivalent simulation model of MMC is proposed.Results of valve power loss analysis of 201-level 500MW MMC operating at 50Hz~1000Hz are presented.It is seen that the valve power loss of a MMC increased by 12,40 and 93%under 200Hz,500Hz and 1000Hz operating frequency.The article concludes that in a device with isolated inner AC system,MMC operating at higher frequency will be more competitive than typical 50Hz/60Hz MMC with moderate increase of operating power loss and significant reduction of the size of the AC components.

Lightweight,self-cleaning and refractory FeCo@MoS_(2)PVA aerogels:from electromagnetic wave-assisted synthesis to flexible electromagnetic wave absorption

The emergence of wearable and foldable electronic devices urges advanced electromagnetic(EM)wave absorbers with maintained performance under deformation.Here FeCo@MoS_(2)poly vinyl alcohol(PVA)aerogels have been fabricated with the assistance of EM waves for simultaneous splitting of the MoS_(2)flakes and dispersive growth of FeCo nanoparticles.The resultants in-return have been used for EM wave absorption with excellent performance,providing minimum reflection loss(RL_(min))of-40.7 dB and a broad effective absorption bandwidth(EAB)of 6.4 GHz at a thickness of 2.5 mm.Real-time compression has been introduced to reveal the evolution of EM parameters.The aerogels maintain satisfactory performance even under 50%compression due to the balance of impedance matching and attenuation.Despite the deterioration of impedance matching,the attenuation is significantly enhanced due to both strengthened conductive loss and magnetic loss.In addition,features such as lightweight,self-cleaning and refractory can be achieved for the aerogels for applications in complex environments.As such this work not only provides a versatile synthetic route assisted by EM wave energy,but also insights on the evolution of absorption performance under deformation together with the design strategy of multifunctional flexible wave absorbers.

Highly conductive,stretchable,durable,skin-conformal dry electrodes based on thermoplastic elastomer-embedded 3D porous graphene for multifunctional wearable bioelectronics

Long-term bioelectric potential recording requires highly reliable wearable dry electrodes.Laser-induced graphene(LIG)dry electrodes on polyimide(PI)films are difficult to conform to the skin due to the non-stretchability and low flexibility of PI films.As a result,high interface impedance and motion artifacts can occur during body movements.Transferring LIG to flexible substrates such as polydimethylsiloxane(PDMS)and Ecoflex allows for stretchability and flexibility.However,the transfer process produces a significant loss of conductivity destroying the structural function and electron conduction properties of the LIG.We found robust physical and chemical bonding effects between LIG and styrene-ethylene-butylene-styrene(SEBS)thermoplastic elastomer substrates and proposed a simple and robust low-conductivity loss transfer technique.Successfully embedded LIG onto SEBS to obtain high stretchability,high flexibility,low conductivity losses.Electrophoretic deposition(EPD)of poly(3,4-ethylenedioxythiophene):polystyrenesulfonic acid(PEDOT:PSS)on LIG forms an ultrathin polymer conductive coating.The deposition thickness of the conductive polymer is adjusted by controlling the EPD deposition time to achieve optimal conductivity and chemical stability.SEBS/LIG/PEDOT:PSS(SLPP)dry electrodes have high conductivity(114Ω/Sq),stretchability(300%)and reliability(30%stretch,15,000 cycles),low electrode-skin impedance(14.39 kΩ,10 Hz).The detected biopotential signal has a high signal-to-noise ratio(SNR)of 35.78 dB.Finally,the feasibility of SLPP dry electrodes for long-term biopotential monitoring and biopotential-based human-machine interface control of household appliances was verified.

Boosting electromagnetic wave absorption of Ti_(3)AlC_(2) by improving effective electrical conductivity

Electromagnetic wave-absorbing(EMA)materials at high temperatures are limited by poor conduction loss(L_(c)).However,adding conductors simultaneously increases the conduction loss and interfacial polarization loss,leading to a conflict between impedance matching(Z_(in)/Z_(0))and electromagnetic wave loss.This will prevent electromagnetic waves from entering the EMA materials,finally reducing overall absorbing performance.Here,the effective electrical conductivity(σ)is enhanced by synchronizing particle size and grain number of Ti_(3)AlC_(2) to increase the conduction loss and avoid the conflict between the impedance matching and the electromagnetic wave loss.As a result,the best-absorbing performance with an effective absorption bandwidth(EAB)of 4.8 GHz(10.6–15.4 GHz)at a thickness of only 1.5 mm is realized,which is the best combination of wide absorption bandwidth and small thickness,and the minimum reflection loss(RL_(min))reaches−45.6 dB at 4.1 GHz.In short,this work explores the regulating mechanism of the EMA materials of effective electrical conductivity by simulated calculations using the Vienna ab-initio Simulation Package(VASP)and COMSOL as well as a series of experiments,which provide new insight into a rational design of materials with anisotropic electrical conductivity.

传导性聋理论及诊断技术

由外耳及中耳病变导致的听力损失称为传导性聋。近年来的临床实践及相关研究表明内耳疾病亦可导致传导性聋，脑组织及脑脊液在将声音传到内耳的过程起重要作用，激光多普勒振荡仪的使用使得对传导性聋病变部位的诊断更加精确。本文就传导性聋理论及诊断技术的新进展进行综述。

3D carbon network supported porous SiOC ceramics with enhanced microwave absorption properties

Porous SiOC ceramic was successfully prepared by pyrolysis of dimethylsilicone oil,silane coupling agent and melamine foam.The microwave absorbing properties of porous SiOC were studied for the first time.At the matching layer thickness of 3.0 mm,the paraffin-based composite with porous SiOC displays a minimum reflection coefficient(RC)of-39.13 d B(11.76 GHz)and an effective absorption bandwidth(EAB)of 4.64 GHz which are much larger than that of paraffin-based composite with ordinary SiOC.It is found that the porous structure of SiOC is crucial to achieve its high microwave absorption performance by improving both the polarization loss and conduction loss.The enhanced polarization loss is originated from the dipole polarization and interfacial polarization,while the improvement of conduction loss is attributed to the carbon skeleton of porous SiOC.These results indicate that porous SiOC ceramic is a promising candidate for high-performance ceramic-based microwave absorbing materials.

Broadband high-performance microwave absorption of the single-layer Ti_(3)C_(2)T_(x)MXene

MXenes,a family of two-dimensional(2D)materials,exhibit peculiar microwave-absorbing behaviors due to their unique chemical composition and structure.Although laminated Ti_(3)C_(2)T_(x) MXenes with a multilayer structure have been used for microwave absorption,real 2D MXenes with a single-layer structure have not yet been investigated.Here,the electromagnetic wave response behavior of single-layer Ti_(3)C_(2)T_(x) MXenes was explored in detail.The permittivity of Ti_(3)C_(2)T_(x) MXene rises dramatically with an increase in filler loading,and Ti_(3)C_(2)T_(x) MXene features a distinct dielectric response wherein dipolar polarization and interfacial polarization makes a greater contribution at low filler loading;conductive loss becomes more prominent at high filler loading.Versus laminated Ti_(3)C_(2)T_(x) MXene,single-layer Ti_(3)C_(2)T_(x) MXene delivers superior absorbing capability:The RLminvalue of SL-Ti_(3)C_(2)T_(x)-22%reaches-43.5 d B at 6.5 GHz,and a broad EAB of 6.88 GHz can be attained at a thickness of 1.8 mm due to enhanced dipolar polarization,interfacial polarization,and conductive loss.This work is of great significance in guiding the future development of MXene-based absorbers.

A Two-Dimensional Semiconductive Metal-Organic Framework for Highly Efficient Microwave Absorption

Comprehensive Summary Advanced microwave absorbing materials(MAMs)are urgently required to eliminate and attenuate microwaves to address the ubiquitous microwave radiations and interference.In this contribution,we report the microwave absorption application of a two-dimensional(2D)semiconductive metal-organic framework(MOF),i.e.,CuHT(HT=4-hydroxythiophenol),without any pyrolysis at high temperature.

Tuning the shell thickness of core-shell α-Fe_(2)O_(3)@SiO_(2) nanoparticles to promote microwave absorption

Various advanced microwave absorbing materials have been developed for reducing/avoiding the harm of microwave radiation.Among them,core-shell structural nanomaterials have been widely fabricated for microwave absorption.However,the“structure-performance”relationship between shell thickness and microwave absorption performance is rarely reported.In this paper,we first explored the“structure-performance”relationship between shell thickness and microwave absorption performance,based on the core-shellα-Fe_(2)O_(3)@SiO_(2)nanoparticles with a constantα-Fe_(2)O_(3)-core size and changeable SiO_(2)-shell thickness.With increasing the SiO_(2)-shell thickness,the microwave absorption ability first increased,then decreased.Under a proper SiO_(2)-shell thickness of 35 nm,α-Fe_(2)O_(3)@SiO_(2)sample achieved the strongest microwave absorbing ability with a reflection loss minimum value of-4.3 d B,better than that of pureα-Fe_(2)O_(3)(-3.8 dB).This enhanced microwave absorption performance was mainly derived from the di-electric loss.Although the absolute value of the reflection loss was relatively low(-4.3 d B),this study shed an important reference on designing next-generation advanced iron oxide-based materials for mi-crowave absorption.