Enhancing Cellular Infiltration on Fluffy Polyaniline-Based Electrospun Nanofibers

Despite the unique properties of polyaniline (PANI), the processability of this smart polymer is associated with challenges. Particularly, it is very difficult to prepare PANI nanofibers due to poor solubility, high charge density, and rigid backbone. The most common approach for solving this problem is blending PANI with a carrier polymer. Furthermore, the major limitations of nanofibers for tissue engineering applications are their low porosity and two-dimensional (2D) structure. In this study, conductive nanofibers were fabricated through electrospinning of PANI/poly(ether sulfone) (PES) with different solvents including dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), and hexafluoroisopropanol (HFIP). The effect of solvent, carrier polymer (PES), and PANI content on formation of 3D conductive nanofibers with appropriate porosity were investigated. It was shown that a solvent with suitable properties should be selected in such a way that the composite nanofibers can be electrospun at the lowest concentration of PES. In this way, the ratio of PANI increased in the scaffold, the electrical conductivity of nanofibers enhanced, and the flat 2D structure of scaffold changed to a fluffy 3D structure. Among the three studied solvents, HFIP with the lowest boiling point and the lowest surface tension was the best solvent for the fabrication of PANI/PES nanofibers. PES could be electrospun at a concentration of 9% w/w in HFIP, while the optimum percentage of PES in DMSO and NMP was above 23% w/w to produce uniform nanofibers. 3D nanofibrous scaffold obtained from 0.5% PANI/9% PES/HFIP solution with electrical conductivity of 3.7 × 10–5 S/Cm and porosity of 92.81 ± 1.23%. Cell infiltration into the 3D nanofibers with low packing density improved compared to densely packed 2D nanofibers

Poly (ɛ-caprolactone) nanofibrous ring surrounding a polyvinyl alcohol hydrogel for the development of a biocompatible two-part artificial cornea

The study aimed to fabricate and characterize a 2-part artificial cornea as a substitute for penetrating keratoplasty in patients with corneal blindness. The peripheral part of the artificial cornea consisted of plasma-treated electrospun poly (ɛ-caprolactone) (PCL) nanofibers, which were attached to a hydrogel disc of polyvinyl alcohol (PVA) as a central optical part. The physical properties of the prepared artificial cornea, including morphology, mechanical properties, light transmittance, and contact angle, were assessed. Cell attachment and proliferation studies were performed on rabbit limbal stem cells. The SEM image of the polymeric system showed that the peripheral part formed a highly porous scaffold that could facilitate tissue biointegration. Assessment of the mechanical properties of the peripheral nanofibrous part and the hydrogel optical part showed suitable elasticity. Young’s modulus values of the electrospun PCL skirt and PVA hydrogel core were 7.5 and 5.3 MPa, respectively, which is in line with the elasticity range of natural human cornea (0.3–7 MPa). The light transmittance of the central part was >85% when measured in the 400–800 nm wavelength range. The plasma-treated PCL nanofibrous scaffold promoted limbal stem cell adhesion and proliferation within 10 days. These results confirmed that the polymeric artificial cornea showed suitable physical properties and good biocompatibility and epithelialization ability

Global burden of 369 diseases and injuries in 204 countries and territories, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019

Background: In an era of shifting global agendas and expanded emphasis on non-communicable diseases and injuries along with communicable diseases, sound evidence on trends by cause at the national level is essential. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) provides a systematic scientific assessment of published, publicly available, and contributed data on incidence, prevalence, and mortality for a mutually exclusive and collectively exhaustive list of diseases and injuries. Methods: GBD estimates incidence, prevalence, mortality, years of life lost (YLLs), years lived with disability (YLDs), and disability-adjusted life-years (DALYs) due to 369 diseases and injuries, for two sexes, and for 204 countries and territories. Input data were extracted from censuses, household surveys, civil registration and vital statistics, disease registries, health service use, air pollution monitors, satellite imaging, disease notifications, and other sources. Cause-specific death rates and cause fractions were calculated using the Cause of Death Ensemble model and spatiotemporal Gaussian process regression. Cause-specific deaths were adjusted to match the total all-cause deaths calculated as part of the GBD population, fertility, and mortality estimates. Deaths were multiplied by standard life expectancy at each age to calculate YLLs. A Bayesian meta-regression modelling tool, DisMod-MR 2.1, was used to ensure consistency between incidence, prevalence, remission, excess mortality, and cause-specific mortality for most causes. Prevalence estimates were multiplied by disability weights for mutually exclusive sequelae of diseases and injuries to calculate YLDs. We considered results in the context of the Socio-demographic Index (SDI), a composite indicator of income per capita, years of schooling, and fertility rate in females younger than 25 years. Uncertainty intervals (UIs) were generated for every metric using the 25th and 975th ordered 1000 draw values of the posterior distribution. Findings: Global health has steadily improved over the past 30 years as measured by age-standardised DALY rates. After taking into account population growth and ageing, the absolute number of DALYs has remained stable. Since 2010, the pace of decline in global age-standardised DALY rates has accelerated in age groups younger than 50 years compared with the 1990–2010 time period, with the greatest annualised rate of decline occurring in the 0–9-year age group. Six infectious diseases were among the top ten causes of DALYs in children younger than 10 years in 2019: lower respiratory infections (ranked second), diarrhoeal diseases (third), malaria (fifth), meningitis (sixth), whooping cough (ninth), and sexually transmitted infections (which, in this age group, is fully accounted for by congenital syphilis; ranked tenth). In adolescents aged 10–24 years, three injury causes were among the top causes of DALYs: road injuries (ranked first), self-harm (third), and interpersonal violence (fifth). Five of the causes that were in the top ten for ages 10–24 years were also in the top ten in the 25–49-year age group: road injuries (ranked first), HIV/AIDS (second), low back pain (fourth), headache disorders (fifth), and depressive disorders (sixth). In 2019, ischaemic heart disease and stroke were the top-ranked causes of DALYs in both the 50–74-year and 75-years-and-older age groups. Since 1990, there has been a marked shift towards a greater proportion of burden due to YLDs from non-communicable diseases and injuries. In 2019, there were 11 countries where non-communicable disease and injury YLDs constituted more than half of all disease burden. Decreases in age-standardised DALY rates have accelerated over the past decade in countries at the lower end of the SDI range, while improvements have started to stagnate or even reverse in countries with higher SDI. Interpretation: As disability becomes an increasingly large component of disease burden and a larger component of health expenditure, greater research and developm nt investment is needed to identify new, more effective intervention strategies. With a rapidly ageing global population, the demands on health services to deal with disabling outcomes, which increase with age, will require policy makers to anticipate these changes. The mix of universal and more geographically specific influences on health reinforces the need for regular reporting on population health in detail and by underlying cause to help decision makers to identify success stories of disease control to emulate, as well as opportunities to improve. Funding: Bill & Melinda Gates Foundation. © 2020 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 licens

The Relationship between Cultural Identity, Intrinsic Motivation and Pronunciation Knowledge of Iranian EFL Learners

Gardener’s (1985) socio-cultural model shows that culture is among the variables that can affect learning languages. In addition, a series of studies were prompted by Dörnyie (2005) to gauge the effect of motivation on language learning. This correlational study endeavored to find out any possible interaction between these variables, i.e., cultural identity, intrinsic motivation, and pronunciation knowledge of Iranian EFL learners at intermediate level. To this end, 9 items from Mathews’ Cultural Identity Questionnaire (2007) (as cited in Bazrafshan, 2015) along with intrinsic/extrinsic motivation questionnaire developed by Noels, Pelletier, Clement, and Vallerand (2000) were given to the 49 intermediate Iranian EFL learners who were selected among 74 learners studying at Mahan Language Institute in Birjand. The participants’ pronunciation knowledge was also measured through an interview. The results of the data analysis through Pearson correlation revealed that cultural identity shows no relationship with pronunciation knowledge of the participants, whereas more intrinsically motivated language learners gained higher scores on the pronunciation test. Pedagogical implications are discussed.

The Effect of Impulsivity vs. Reflectivity on Reading Comprehension of Iranian EFL Learners

In recent years attention has been accorded to language learners’ affective factors and learning styles. Two of the significant learning styles are impulsivity and reflectivity which have not been studied as much as other styles such as introversion and extroversion. This study endeavored to find out whether or not impulsivity and reflectivity have any effect on reading comprehension of Iranian English as a Foreign Language (EFL) learners. Seventy two language learners were selected from 4 intact classes out of 112 learners. Nelson proficiency test was given to the participants as homogeneity test. Next, Barrat’s (1995) impulsiveness questionnaire was given to the participants. Based on the results of the questionnaire, the participants formed 3 different groups, i.e., a reflective group (n=25), impulsive group (n=25) and a control group (n=22). The control group consisted of less impulsive and less reflective learners based on Barrat’s scale. An IELTS reading test (general module) was administered to the participants. Based on the results of independent samples t-test, it was found that impulsivity and reflectivity do not have any effect on reading comprehension of Iranian EFL learners. Pedagogical implications are discussed.

Investigation of Long Non-coding RNA HOX A11-AS Expression in Iranian Patients with Glioblastoma: A Quantitative Study

Background and Objectives: Glioblastoma is one of the most malignant and common brain tumors, accounting for about half of all gliomas. Glioblastoma is a central nervous system tumor that originates from the glial tissue of the brain. The present study aimed to investigate changes in the expression of long non-coding RNA HOXA11-AS as a possible biomarker in glioma.   Methods: For the purposes of the present study, first, the medical records of the patients in Imam Hossein Hospital in Tehran, Iran were reviewed. The ethical considerations were respected as well; accordingly, written informed consent was obtained from the patients and the code of ethics was achieved as well. Finally, the paraffin blocks, including the biopsy of brain tumor tissue of the patients who referred to Imam Hossein Hospital during 2015-17 were collected and their degrees were confirmed by the pathologist. In total, 50 samples of grades 1 and 2 as well as 50 samples of grades 3 and 4 were examined in this research project. The RNA extraction and cDNA synthesis were performed for all the tissue samples donated by the patients. Subsequently, a specific primer and probe were designed and the expression of the HOXA11-AS gene was investigated using real-time polymerase chain reaction technique. The mean age of the subjects was 43.70±16.416 years. The collected data were analyzed in SPSS software (version 20) using descriptive and analytical statistics. Moreover, the expression levels of this gene in lower- and higher-grade tumor tissues were compared using the unpaired samples t-test.   Results: Based on the results, the tumor samples with grade three and four underwent a 2.76 fold increase in expression (fold change), compared to tumor samples with grade one and two. This difference was statistically significant.   Conclusion: Based on the findings, it can be concluded that the expression of the HOXA11-AS gene has a significant positive relationship with the degree of disease (P=0.0002)

Novel nanofiber-based triple-layer proton exchange membranes for fuel cell applications

New types of triple-layer membranes were fabricated using multi-step impregnation of Nation in electrospun webs based on bead-free nanofibers of sulfonated poly(ether sulfone) (SPES). The results showed that the fabricated nanofiber-filled membrane owing to its reduced methanol permeability as well as sufficient proton conductivity and membrane selectivity can be used as a promising proton exchange membrane for direct methanol fuel cell (DMFC) applications. The single cell DMFC performance results revealed that the SPES nanofiber-based triple-layer membranes have higher electrochemical performance than commercial Nation membranes. (C) 2011 Elsevier B.V. All rights reserved

Nanofiber-based polyelectrolytes as novel membranes for fuel cell applications

Partially sulfonated poly(ether sulfone) (SPES) was prepared and electrospun to bead-free nanofibers. The obtained data from solution conductivity measurements and scanning electron microscopy illustrated that sulfonation leads to a drastic increase in polymer solution conductivity and a considerable decrease in nanofiber diameter and a narrower diameter distribution. The new types of membranes were fabricated using Nafion-filled electrospun mats. The porous SPES nanofibrous membranes were impregnated with appropriate amount of Nafion solution. After a good pore-filling, an excess amount of Nafion solution was used to form a uniform top layer (SPES-N-N). Another bilayer polyelectrolyte membrane was prepared by direct electrospinning of SPES nanofibers on Nafion112 membrane's surface and followed by impregnation of Nafion solution into the pores of electrospun SPES (SPES-N-N112). The membranes were characterized by methanol permeability, proton conductivity, oxidative/hydrolytic stability as well as single cell direct methanol fuel cell (DMFC) performance tests. The proton to methanol selectivity of the SPES nanofiber-based bilayer membranes is about 53,680 and 45,500S s cm(-3) for SPES-N-N and SPES-N-N112 in comparison with 28,300 and 40,500S s cm(-3) for Nafion112 and Nafion117, respectively. The single cell DMFC performance results revealed that the SPES nanofiber-based-bilayer membranes have higher electrochemical performance than Nafion112 and Nafion117 membranes especially in elevated methanol concentration. The results showed that the fabricated bilayer membranes can be used as a promising polyelectrolyte membrane for fuel cell applications (C) 2010 Elsevier B.V. All rights reserved