Dry Membrane Research Articles

DEGREE OF HEARING LOSS IN INACTIVE MUCOSAL CHRONIC OTITIS MEDIA AND ITS CORRELATION WITH SITE AND SIZE OF TYMPANIC MEMBRANE PERFORATION- AN OBSERVATIONAL STUDY

Background: Studies have persistently associated the site and size of the tympanic membrane (TM) with the magnitude of hearing loss;however,the results are mixed and inconclusive on the effect of the site of the perforation on the hearing loss. Therefore, we conducted the present study to investigate the relationship between the size and site of TM perforation and hearing loss in inactive mucosal chronic otitis media. Methods: We conducted a hospital-based observational, prospective study in the Postgraduate Department of Otorhinolaryngology, Head and Neck Surgery, Government Medical College Srinagar, and recruited 94 patients diagnosed to have inactive mucosal chronic otitis media with dry tympanic membrane perforation. In addition to the site and size of TM perforation, the magnitude of hearing loss was also estimated. Results: We recruited 94 subjects presenting acute otitis media with TP perforation. The mean age (±SD) of cases was 36.3(±4) and males showed a marginal over-representation over females (male to female ratio: 1.2:1). We observed a positive correlation of the size of TM perforation with the average hearing loss. Moreover, subjects having perforations in the posterior ear reported higher average hearing loss. Conclusion: We report a positive correlation of the size of TM perforation with the average hearing loss and subjects having perforations in the posterior ear reported higher average hearing loss. However, more replicative studies with a larger sample size are warranted to substantiate our findings.

Acid-triggered polyether sulfone - Polyvinyl pyrrolidone blend anion exchange membranes for the recovery of titania waste acid via diffusion dialysis

Dense PES (polyether sulfone) - PVP (polyvinyl pyrrolidone) blend membranes are proposed to recover titania waste acid by diffusion dialysis. These dense membranes can simply be prepared by the solution casting method, and the spontaneous quaternization of the N and O atoms in pyrrolidone with H+ in sulfuric acid solution turns them into effective anion exchange membranes very suitable for the fractionation of sulfuric acid/sulfate. In this work, the influence of the PVP molecular weight (K30 and K90), the composition of the casting solution and the concentration of sulfuric acid in the post-treatment step on the physicochemical properties and mass transfer performance of the membranes are systematically investigated. It is found that the content of absorbed sulfuric acid in the dense membranes increases with the increasing PVP content (20–60 wt%) in the membranes, after the equilibration in 2.68 M H2SO4. The content of H+ in blend membranes with PVP K30 (K30 series) is 0–5.73 mmol/(g dry membrane), while that in the membranes with PVP K90 (K90 series) is 0–5.34 mmol/(g dry membrane). The permeability coefficients of H2SO4 and FeSO4 in the K30 and the K90 series membranes also increase gradually, ranging from 0–200 × 10−9 m2/h and 0–8.81 × 10−9 m2/h, respectively. The largest selectivity coefficient of H2SO4/FeSO4 can reach 1800. The permeability coefficients of H2SO4 and FeSO4 also increase gradually with the increase of the solution acid concentration, and the selectivity remains excellent. These PES-PVP dense membranes show very good chemical stability, the permeability coefficients of H2SO4 and FeSO4 for a blend membrane with 55 wt% PVP K30 remain unchanged in a 2.68 M H2SO4 solution for 337 days. This study would provide valuable guidance for the application of these PES-PVP blend anion exchange membranes in the recovery of titania waste acid by diffusion dialysis.

Comparative study between temporalis fascia graft with and without addittion of cyanoacrylate glue in myringoplasty

Background: Tissue adhesives are often used in myringoplasty because they can hold the graft in place and help the graft absorb by acting as a framework. Aim of the study: The goal is to look at the temporalis fascia graft used in myringoplasty with and without cyanoacrylate glue and compare the two. Patients, and methods: Fifty patients with dry central tympanic membrane perforation were treated with type I tympanoplasty over the course of 1.5 years. In each instance, the autogenous temporalis fascia graft was spot welded and fixed to flaps and the surrounding tissue using glue. Myringoplasty was done on 50 people, and they were randomly put into two groups: those who had cyanoacrylate glue put on the temporalis fascia graft and those who didn't. Results: Each group had 25 cases, and there were no big differences between the groups in terms of age, direction, or size of the tympanic membrane hole. After 6 weeks, there wasn't much difference between the glue group and the control group. In the glue group, 72% had healed and 28% had perforated, while in the control group, 64% had healed and 36% had perforated (p-value 0.544).

Metaplastic and energy-efficient biocompatible graphene artificial synaptic transistors for enhanced accuracy neuromorphic computing

CMOS-based computing systems that employ the von Neumann architecture are relatively limited when it comes to parallel data storage and processing. In contrast, the human brain is a living computational signal processing unit that operates with extreme parallelism and energy efficiency. Although numerous neuromorphic electronic devices have emerged in the last decade, most of them are rigid or contain materials that are toxic to biological systems. In this work, we report on biocompatible bilayer graphene-based artificial synaptic transistors (BLAST) capable of mimicking synaptic behavior. The BLAST devices leverage a dry ion-selective membrane, enabling long-term potentiation, with ~50 aJ/µm2 switching energy efficiency, at least an order of magnitude lower than previous reports on two-dimensional material-based artificial synapses. The devices show unique metaplasticity, a useful feature for generalizable deep neural networks, and we demonstrate that metaplastic BLASTs outperform ideal linear synapses in classic image classification tasks. With switching energy well below the 1 fJ energy estimated per biological synapse, the proposed devices are powerful candidates for bio-interfaced online learning, bridging the gap between artificial and biological neural networks.

Influence of carbon-based fillers on photoactive mixed matrix membranes formation

Direct solar membrane distillation is an innovative configuration that uses a photoactive membrane to transform solar light into heat, sensibly reducing temperature polarization effects and feed temperature decrease along the module. This approach has been proved capable of increasing membrane distillation performance and efficiency.In this work, photoactive mixed matrix membranes were prepared by non-solvent induced phase separation procedure using a polyvinylidene fluoride dope solution containing different carbon-based fillers. Commercial graphite and graphene were selected because of their large specific surface area and their influence on the membrane structure and photothermal properties was compared to the results obtained using carbon black. The introduction of the filler allowed to obtain temperatures as high as 60 °C on the dry membrane surface when exposed to a simulated sunlight source. Both graphene and graphite had minor effect on the membrane morphology while carbon black increased the mean pore size of the membrane. The direct solar membrane distillation tests, performed using both pure water or a 90 g/L NaCl solution as feed, showed promising improvements (up to 70%) of the distillation flux under light irradiation.

The effect of irrigation water salinity on the morph-physiological and biochemical properties of spinach under deficit irrigation conditions

The quality and quantity of the water used in agriculture are important factors to ensure sustainable agricultural production. It is crucial to determine the responses of plants under deficit irrigation conditions in the arid and semi-arid areas to varying salinity of irrigation water. The responses of spinach were investigated in terms of agronomic and physiological aspects to different water salinities and water stress levels. In this study, a total of 15 experimental treatments were carried out, including five different levels of water salinity (S1, 0.3 dS/m; S2, 1.5 dS/m; S3, 3.0 dS/m; S4, 4.5 dS/m and S5, 6.0 dS/m) and three different irrigation levels (I100; full irrigation, I75; 25% water deficit, and I50; 50% water deficit). The salinity of irrigation water had statistically significant effects on the fresh and dry weight, leaf area, membrane damage, color pigments, and carotenoid values in spinach. Similarly, irrigation water salinity has a significant effect on enzyme activities such as catalase (CAT), superoxide dismutase (SOD), peroxidase (POD), and malondialdehyde (MDA), as well as proteins, proline, and hydrogen peroxide (H2O2) contents. Furthermore, the application of different irrigation levels in spinach; resulted in a significant difference in the fresh and dry weights, the number of leaves per plant, leaf area, leaf water content, and color pigments. Additionally, enzyme activities such as CAT, SOD, and MDA, as well as protein and proline content, were significantly affected by different irrigation levels. The highest yield response factor (ky) calculated in different irrigation water salinity applications was 1.79 in the S1 application, followed by 1.32 in the S2 (1.5 dS/m) application. It was found that ky values in spinach were less than 1.00 in irrigation with an EC of 3.0 dS/m and above; thus, making it tolerant to water shortages. In the case of irrigation with saline water such as 4.5 and 6.0 dS/m, the yield at I75 (25% water stress) irrigation level was found closely related to the treatments of full irrigation or even slightly higher. Therefore, in the water shortage regions with saline irrigation water, 25% water restriction on spinach has been proposed as an important strategy for the protection of water resources as well as control of soil salinity.

Proton-exchange membrane fuel cell ionomer hydration model using finite volume method

In this paper a dynamic membrane electrode assembly water transport model, based on the Finite Volume Method, is presented. The purpose of this paper is to provide an accessible and reproductible model capable of real time simulation. To this aim, a detailed explanation is provided regarding the equations and methods used to compute the physical-based fuel cell model. Additionally, the model is purposely developed using basic code (on Matlab™), to not be limited to a single programming language. Two phase water transport through multi-gaseous porous media (electrodes), interfacial transport, as well as diffusion, convection, and electro-osmosis within the polymer are considered. The main novelty relies in the restructuring of all equations into a single implicit system, which can iteratively be resolved through LU decomposition. This computationally efficient method allows the model to be capable of real-time simulation, by displaying the membrane water content profile evolution on a 3D figure. For nominal PEMFC operating conditions, a dry membrane reaches 35% of its final water concentration value after 2 s, and fully converges after 20 s. The final water content profile displays an 18% gradient (9 and 11 molecules per sulfonic acid sites on the anode and cathode sides, respectively). To calibrate and validate this model, mass transfer (flowmeter) and electrical (ohmmeter) methods have been applied.

Α Novel Sutureless Pterygium Excision Surgery Using Human-Derived Dehydrated Amniotic Membrane

There are many surgical techniques available for the management of pterygium. Excision with limbal conjunctival autograft is currently the most popular surgical procedure and has been shown to have low recurrence rate and fewer complications. The fixation of limbal conjunctival autograft is performed with either sutures or fibrin glue. The use of sutures results in longer operating time and intense postoperative irritation and epiphora. We describe a new technique for pterygium excision using a human amniotic membrane-derived dry matrix (Omnigen®; Nottingham, UK: Nu-Vision Biotherapies). The use of Omnigen instead of conjunctival autograft in pterygium surgery is a new promising technique and results in shorter operation time, easier graft fixation, reduction in complications, and less postoperative discomfort. This is a simple technique for pterygium surgery with dry amniotic membrane matrix and without the need for anchoring limbal sutures or an assistant holding the graft whilst it is glued in place.

Characterizing surface porosity of porous membranes via contact angle measurements

This investigation attempts to establish and verify a novel method for quantifying surface porosity of porous polymeric membranes via contact angle measurements. Herein, we fabricate a series of porous membranes via nonsolvent induced phase separation (NIPS) comprising different concentrations of polyvinylidene fluoride (PVDF) and PVDF-poly (methyl methacrylate) block co-polymer (PVDF-PMMA) with different concentrations of water and isopropyl alcohol (IPA) in the coagulation bath. Both sessile drop and captive bubble contact angle measurements are used to determine contact angles (and porosity) for both dry and wet membranes, respectively. The former method is probably applicable for membrane distillation, aeration and de-aeration where liquid water does not saturate the membrane, whereas the latter may be more indicative of pressure-driven aqueous membrane separations where the membrane is saturated through its cross-section. Image analysis of scanning electron microscope (SEM) images quantified dry membrane surface porosity. We propose a simple analytical model to obtain wet and dry membrane surface porosity from contact angle measurements. Our results suggest that the surface porosity calculated from both wet and dry contact angle data correlates strongly with the surface porosity calculated from SEM values. However, wet contact angles of the membranes with high porosities produce significantly higher porosity values, which also establishes the importance of porous membrane swelling in determining membrane porosity for aqueous membrane separations.

Platinum-coated silicotungstic acid-sulfonated polyvinyl alcohol-polyaniline based hybrid ionic polymer metal composite membrane for bending actuation applications

An electro-stimulus-responsive bending actuator was developed by synthesizing a non-perfluorinated membrane based on silicotungstic acid (SA), sulfonated polyvinyl alcohol (SPVA), and polyaniline (PANI). The membrane was developed via solution casting method. The dry membrane SA/SPVA showed a sufficient ion-exchange potential of 1.6 meq g−1 dry film. The absorption capacity of the membrane after almost 6 h of immersion was found to be ca. 245% at 45 °C. The electroless plating with Pt metal was carried out on both sides of the membrane that delivered an excellent proton conductivity of 1.9 × 10−3 S cm−1. Moreover, the scanning electron microscopy (SEM) was conducted to reflect the smooth and consistent surface that can prevent water loss. The water loss capacity of the membrane was found to be ca. 33% at 6 V for 16 min. These results suggest a good actuation output of the ionic polymer metal composite (IPMC) membrane once the electrical potential is applied. The electromechanical characterization displayed a maximum tip displacement of 32 mm at 3 V. A microgripping device based on multifigure IPMC membrane may be developed showing a good potential in micro-robotics.

Effect of Impregnated Phenolic Resins on the Cellulose Membrane for Polymeric Insulator

In this study, a cellulose membrane (CM) was chemically treated with phenolic (PF) resin to improve its performance as a polymeric insulator. The CM was prepared from kenaf pulp, and the PF was synthesized from oil palm empty fruit (EFB) fibre. Four different concentrations of synthesized PF resin (5, 10, 15, and 20 wt.%) were impregnated under wet or dry conditions. Thermal analysis of the phenolic cellulose membrane (PCM) showed that the samples had good chemical interaction and compatibility. The PF uptake in the wet phenolic cellulose membrane (PCMW) was higher than in the dry phenolic cellulose membrane (PCMD). During the PF uptake, the CM underwent solvent exchange and absorption in wet and dry membranes, respectively. This difference also affected the crosslinking of PCM samples via the formation of methylene bridges. Due to the PF treatment, the PCM showed lower water absorption than CM. The PF concentrations also affect the surface roughness and electrical properties of PCM samples. These findings prove that PCM can be used as a renewable and green polymer electrical insulator.

ROLE OF FIBRIN GLUE FOR BETTER SUCCESS RATE IN MYRINGOPLASTY

Objective: To see graft uptake success rate in platelet rich fibrin aided underlay myringoplasties using temporalis fascia graft compared to conventional underlay myringoplasties.
 Study Design: Double blind randomized controlled trial study.
 Place and Duration of Study: ENT department, Pakistan Naval Ship Shifa Hospital, from Jan to Jun 2019.
 Methodology: Sixty cases with dry central tympanic membrane perforations were recruited. The patients suffering from sensori-neural hearing loss and co-morbidities like diabetes were excluded. The sampling technique was probability simple random. Patients were divided into two groups by lottery method. Statistical analysis was performed by using SPSS. The chi square test was applied to calculate p-value.
 Results: Out of total 60 patients 38 were males and 22 were females. Study group’s (Fibrin) mean age was 31.77 ± 12.43 years and Control group’s mean age was 27.53 ± 11.41 years. All the patients in platelet rich fibrin group had successful graft uptake at 2 months follow-up. In control group with conventional technique 23 out of 30 patients had successful graft uptake and rest 7 patients had different issues leading to graft rejection.
 Conclusion: In under lay myringoplasty procedure, application of platelet rich fibrin on temporalis fascia graft edge and perforation edges has significantly improved the successful uptake rate of graft.

MIDDLE EAR DISORDERS AMONG CLEFT LIP AND PALATE IN CHILDREN: A CONJOINT EXPOSITION

Objective: To analyze the frequency of middle ear disorders among the cleft lip and palate and association with hearing Loss.
 Study Design: Cross Sectional analytical study.
 Place and Duration of Study: Audiology Department of Cleft Hospital, Gujrat and ENT department of National Institute of Rehabilitation Medicine, Islamabad, from Oct 2018 to Mar 2019.
 Methodology: We recruited a sample of 100 cleft lip and palate children of both genders, aged 3 month to 12 years, using nonprobability sampling. Screening was performed with otoscopy, tympanometry and hearing assessment.
 Results: Out of sample population, 62% were males and 38% females with a mean age of 2.27 ± 2.73 years. The middle ear disorders were found to be 70%. Among these otitis media with effusion was the most common 43 (61.43%), followed by Acute otitis media 8 (11.43%) and Eustachian tube dysfunction 6 (8.57%). Tympanosclerosis and dry tympanic membrane perforation were the least common. Statistically significant association of hearing loss was found with the middle ear disorders (p<0.001).
 Conclusion: Middle ear disorders especially otitis media with effusion are common in cleft lip/ palate children.

Nanofibrous Membrane with Encapsulated Glucose Oxidase for Self-Sustained Antimicrobial Applications.

Polyvinyl alcohol (PVA) nanofibrous membrane, consisting of separately encapsulated glucose oxidase (GOx) and glucose (Glu) nanofibers, was prepared via simultaneously electrospinning PVA/GOx and PVA/Glu dopes. The as-prepared pristine membrane could self-sustainably generate hydrogen peroxide (H2O2) only in contact with an aqueous solution. The H2O2 production level was well maintained even after storing the dry membrane at room temperature for 7 days. Cross-linking the membrane via reaction with glutaraldehyde (GA) vapor could not only prevent the nanofibrous membrane from dissolving in water but also prolonged the release of H2O2. The sustained release of H2O2 from the membrane achieved antimicrobial capability equivalent to that of 1% H2O2 against both Escherichia coli and Staphylococcus aureus. Gram(+) S. aureus cells were more susceptible to H2O2 than Gram(−) E. coli and >99% of S. aureus were killed after 1 h incubation with the membrane. Pristine and GA-crosslinked nanofibrous membrane with in situ production of H2O2 were self-sterilized in which no microorganism contamination on the membrane could be detected after 2 weeks incubation on an agar plate. The GOx/Glu membrane may find potential application as versatile antimicrobial materials in the field of biomedicine, in the food and health industries, and especially challenges related to wound healing in diabetic patients.

Epidermal Basement Membrane Substitutes for Bioengineering of Human Epidermal Equivalents

Epidermal basement membrane, a tightly packed network of extracellular matrix (ECM) components, is a source of physical, chemical, and biological factors required for the structural and functional homeostasis of the epidermis. Variations within the ECM create distinct environments, which can affect the property of cells in the basal layer of the epidermis and subsequently affect keratinocyte differentiation and stratification. Very little attention has been paid to mimicking basement membrane in organotypic cultures. In this study, using parameters outlined in a consensus on the quality standard of organotypic models suitable for dermatological research, we have evaluated three basement membrane substitutes. We compared fibronectin with three complex three-dimensional matrices: Matrigel, decellularized dermal fibroblast‒produced and ‒assembled ECM, and a dry human amniotic membrane. Our results suggest that Matrigel is not a suitable substrate for human epidermal equivalent culture, whereas the two other complex three-dimensional substitutes, decellularized dermal fibroblast‒produced and ‒assembled ECM and dry human amniotic membrane, were superior to single layer fibronectin coating. Human epidermal equivalents cultured on either decellularized dermal fibroblast‒produced and ‒assembled ECM or on dry human amniotic membrane generated hemidesmosomes, whereas those on fibronectin did not. In addition, human epidermal equivalent cultured on decellularized dermal fibroblast‒produced and ‒assembled ECM and on dry human amniotic membrane can be maintained in culture 4 days longer than human epidermal equivalent cultured on fibronectin without compromising the barrier function.

Polyvinylamine-grafted polypropylene membranes for adsorptive removal of Cr(VI) from water

There are huge demands for the development of green, environmentally friendly, and easily prepared cationic adsorbents for treatment of chromium-contaminated water. In this research, we demonstrate the fabrication of a novel polyvinylamine-grafted polypropylene membrane (PPM-PVAm) for Cr(VI) adsorption. Based on a rapid two-step method, polypropylene membrane (PPM) was grafted with high biomedical safety N-vinylformamide (NVF), and then amino groups were generated via hydrolysis of the poly(N-vinylformamide) (PNVF) and these amino groups could be protonated under acidic condition as Cr(VI) adsorbing sites. The effects of both the PNVF grafting rate and its degree of hydrolysis on the adsorption performance of PPM-PVAm were investigated. The membrane with a PNVF grafting rate around 55% (wt) and a degree of hydrolysis around 70–80% exhibits the best performance for Cr(VI) adsorption under the optimal conditions, i.e. pH 2 at about 40 °C. The adsorption of Cr(VI) on PPM-PVAm matches the Langmuir model, showing a maximum Cr(VI) adsorption capacity of 208.3 mg per gram dry membrane. PPM-PVAm could be deprotonated under alkaline condition so the adsorbed Cr(VI) could be easily removed by NaOH/NaCl aqueous solution. The membrane shows excellent recycling performance, and 90.6% of the adsorption capability remains even after 10 cycles of adsorption-desorption test. Combining the unique performance and eco-friendly process in the fabrication of the membrane, PPM-PVAm shows great potential in adsorptive removal of Cr(VI) from water.

Clay Ceramic Support Membrane Optimization Using Factorial Design Approach

In the present study, the effect of Sintering temperature, Particle size and Heating rate of the ceramic support membrane Elaboration based on dry clay were evaluated using full factorial design and investigated by porosity and mechanical strength measures. The flat supports have been prepared from 5 g of the material with a two fraction 2 and 30 µm, the extrusion was performed using the uniaxial pressing in applicant a pressure of 12 tones, the supports sintered between 900° C and 1200°C with a different heating rate (1°C/min and 10°C/min). By using full factorial design 23, it was found that the sintering temperature is the main controlling factors of the physical properties of dry ceramic support membrane, and its increase had a positive effect on Mechanical strength and negative effect on porosity. The interactions between the factors were relatively less important, and they had different (antagonistic/synergetic) influence on the properties. The optimal factors to elaborate the support membrane include a particle size of 2 µm, sintering temperature of 950°C, Heating rate of 1°C predicting the porosity of 40, 8% and Mechanical strength of 12 MPa.

Features of Thermomechanical Stability of Anionic-Cation Exchange Matrix "Polikon AC" on Viscose Non-Woven Materials.

The thermomechanical stability of the anion–cation exchange matrix “Polikon AC” on viscose nonwoven materials is investigated. In this work, a molecular model of a solvation environment for experimentally obtained “Polikon AC” mosaic membranes is refined. Mosaic membranes on a viscose fiber base were fabricated by the method of polycondensation filling. The temperature dependence of deformation was investigated for dry and wet anion and cation exchange membrane components at a constant tensile load of 1.5 N and a heating rate of 8 °C/min. The effect of moisture content on the deformation of anionite and cationite fragments under a constant external tensile load of 1.5 and 3 N in a temperature range up to 100 °C was studied.

A reverse approach to evaluate membrane pore size distribution by the bubble gas transport method using fewer experimental data points

Membrane technologies have been successfully developed as the separation and purification processes, such as desalination, wastewater treatment, gas separation and so forth. It is known that membrane pore size and pore size distribution (PSD) are the factors by which membrane performance is significantly affected. In this study, a novel mathematical model is presented to evaluate the PSD. Although the new model is based on the bubble gas transport method, it is different from the conventional approach since this model starts from the assumption of a distribution function, typically Gaussian normal distribution, for the PSD, and a flow rate versus pressure line is drawn theoretically based on the assumed PDS. Then, the mean pore size and standard deviation of the PSD are optimized by the best fit of the theoretical line to the experimental one using the nonlinear regression analysis. A unique feature of the proposed model is that fewer experimental data points are necessary to find the optimal PSD. In addition, experiments with the dry membrane are no longer required. The PSDs estimated by this model for three commercial membranes were compared with those obtained by the conventional method, and an excellent agreement was observed.

A STUDY ON CORRELATION OF SIZE AND SITE OF TYMPANIC MEMBRANE PERFORATION WITH DEGREE OF CONDUCTIVE HEARING LOSS IN CHRONIC OTITIS MEDIA

Background: Tympanic membrane perforations are common cause of hearing loss. This study was designed to analyze the relation between tympanic membrane perforation and conductive hearing loss. Materials and Methods: In this prospective study, patients with dry tympanic membrane perforations of safe type were included. The patients were divided into groups in according to size, site and duration of perforation. Based on the inclusion and exclusion criteria a total of 100 patients were included in this study. All the patients clinical data was analyzed statistically using paired t-test. Results:Hearing loss increased as the size of perforation increased. Posterior quadrant perforations were associated with more hearing loss as compared to anterior quadrant perforations. Also duration of disease was in linear relation with mean hearingloss. Conclusions: The degree of conductive hearing loss as a result of tympanic membrane perforation would be expected with the size, site and duration of perforation. Keywords: Tympanic membrane, Conductive hearing loss, Perforation, hearing loss, posterior quadrant, ear.