Photo-Patternable, High-Speed Electrospun Ultrafine Fibers Fabricated by Intrinsically Negative Photosensitive Polyimide.
Ontology highlight
ABSTRACT:
SUBMITTER: Qi L
PROVIDER: S-EPMC8296557 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:Sugarcane bagasse (SCB) is an abundant by-product of sugar refining that can be utilized as a raw material for cellulose isolation for several industrial applications. Electrospinning has garnered attention in recent years because it allows the preparation of cellulosic materials with unique properties. In this study, cellulose was isolated from sugarcane bagasse and acetylated to fabricate fine acetate cellulose fibers through electrospinning. Subsequently, the electrospun fibers were deacetylated and cationized in order to produce functionalized materials with potential textile applications. The functional fibers were colored with an anionic dye (vinyl sulfone) with and without the presence of salt and were evaluated according to dye fixation, color attributes, morphological characteristics, and thermal stability. Cationic cellulose fibers that were dyed without added salt were found to be brighter and demonstrated better color fixation than those with added salt. In addition, morphological analysis performed using scanning electron microscopy demonstrated that cationized fibers dyed without added salt were better preserved at this stage. The cationic fiber also evidenced a high-temperature resistance, exhibiting a degradation temperature above 236 °C. The results suggest that cellulose fibers dyed in this manner can potentially be considered for use in textile applications due to their suitable dye fixation and tunable porosity (i.e., breathability).
| S-EPMC8621662 | biostudies-literature
Project description:BackgroundMelanopsin-expressing intrinsically photosensitive retinal ganglion cells (ipRGC) area third class of photoreceptors in the retina in addition to rods and cones. They are a small heterogeneous population of cells primarily mediating non-image-forming visual functions.ObjectiveThis article provides an overview of the current understanding of the functions and the diversity of ipRGCs. It moreover gives an insight into clinically and translationally relevant aspects and treatment options.Material and methodsNarrative review article.ResultsipRGCs make up ~1-2% of all retinal ganglion cells and are divided into 6 specialized subtypes. With the photopigment melanopsin they can trigger light responses without rod or cone input and can relay irradiance information to various centers of the brain. Depending on the subtype, ipRGCs mediate non-image-forming tasks, such as the pupillary light reflex or synchronizing the circadian clock, and image-forming tasks, such as contrast optimization. ipRGCs exhibit differential resilience against optic nerve damage, making them an interesting study object for the development of neuroprotective strategies. In addition, melanopsin is an attractive optogenetic tool for vision restoration.ConclusionKnowledge on ipRGC physiology is indispensable for understanding frequent clinical observations. Their functional and morphological features are the subject of active research, which highlights novel translational strategies.
| S-EPMC9005408 | biostudies-literature
Project description:Multimaterial fibers engineered to integrate glasses, metals, semiconductors, and composites found applications in ubiquitous sensing, biomedicine, and robotics. The longitudinal symmetry typical of fibers, however, limits the density of functional interfaces with fiber-based devices. Here, thermal drawing and photolithography are combined to produce a scalable method for deterministically breaking axial symmetry within multimaterial fibers. Our approach harnesses a two-step polymerization in thiol-epoxy and thiol-ene photopolymer networks to create a photoresist compatible with high-throughput thermal drawing in atmospheric conditions. This, in turn, delivers meters of fiber that can be patterned along the length increasing the density of functional points. This approach may advance applications of fiber-based devices in distributed sensors, large area optoelectronic devices, and smart textiles.
| S-EPMC7760470 | biostudies-literature
Project description:Intrinsically photosensitive retinal ganglion cells (ipRGCs) are a subset of cells that participate in image-forming and non-image-forming visual responses. Although both functional and morphological subtypes of ipRGCs have been described in rodents, parallel functional subtypes have not been identified in primate or human retinas. In this study, we used a human organ donor preparation method to measure human ipRGCs' photoresponses. We discovered three functional ipRGC subtypes with distinct sensitivities and responses to light. The response of one ipRGC subtype appeared to depend on exogenous chromophore supply, and this response is conserved in both human and mouse retinas. Rods and cones also provided input to ipRGCs; however, each subtype integrated outer retina light signals in a distinct fashion.
| S-EPMC7120228 | biostudies-literature
Project description:Surface modification of polyimides (PIs) using electrospinning would significantly improve the performance of TENGs because of the larger surface area of the electrospun friction layer. However, PIs generally have high solvent resistance, so it is complicated to convert them into nanofibers using electrospinning process. This study aims to fabricate PI nanofibers via simple, one-step electrospinning and utilize them as a friction layer of TENGs for better performance. PI nanofibers were directly electrospun from PI ink made of polyimide powder without any additional process. The effect of PI concentration on spinnability was investigated. Uniform and continuous nanofibrous structures were successfully produced at concentrations of 15?wt% and 20?wt%. Electrospun PI nanofibers were then utilized as a friction layer for TENGs. A TENG with 20?wt% produced an open circuit voltage of 753?V and a short circuit current of 10.79 ?A and showed a power density of 2.61?W?m-2 at a 100 M? load resistance. During tapping experiment of 10,000 cycles, the TENG could stably harvest electrical energy. The harvested energy from the proposed TENG is sufficient to illuminate more than 55 LEDs and drive small electronic devices, and the TENGs exhibit excellent performance as a wearable energy harvester.
| S-EPMC7026082 | biostudies-literature
Project description:A subset of ganglion cells in the mammalian retina express the photopigment melanopsin and are intrinsically photosensitive (ipRGCs). These cells are implicated in non-image-forming visual responses to environmental light, such as the pupillary light reflex, seasonal adaptations in physiology, photic inhibition of nocturnal melatonin release, and modulation of sleep, alertness, and activity. Morphological studies have confirmed the existence of at least three distinct subpopulations of ipRGCs, but studies of the physiology of ipRGCs at the single cell level have focused mainly on M1 cells, the dendrites of which stratify solely in sublamina a (OFF sublamina) of the retinal inner plexiform layer (IPL). Little work has been done to compare the functional properties of M1 cells to those of M2 cells, the dendrites of which stratify solely in sublamina b (ON sublamina) of the IPL. The goal of the current study was to compare the morphology, intrinsic light response, and intrinsic membrane properties of M1 and M2 cells in the mouse retina. Here we demonstrate additional morphological differences between M1 and M2 cells as well as distinct physiological characteristics of both the intrinsic light responses and intrinsic membrane properties. M2 cells displayed a more complex dendritic arborization and higher input resistance, yet showed lower light sensitivity and lower maximal light responses than M1 cells. These data indicate morphological and functional heterogeneity among ipRGCs.
| S-EPMC2752349 | biostudies-literature
Project description:Intrinsically photosensitive retinal ganglion cells (ipRGCs) are recently discovered photoreceptors in the mammalian eye. These photoreceptors mediate primarily nonimage visual functions, such as pupillary light reflex and circadian photoentrainment, which are generally expected to respond to the absolute light intensity. The classical rod and cone photoreceptors, on the other hand, mediate image vision by signaling contrast, accomplished by adaptation to light. Experiments by others have indicated that the ipRGCs do, in fact, light-adapt. We found the same but, in addition, have now quantified this light adaptation for the M1 ipRGC subtype. Interestingly, in incremental-flash-on-background experiments, the ipRGC's receptor current showed a flash sensitivity that adapted in background light according to the Weber-Fechner relation, well known to describe the adaptation behavior of rods and cones. Part of this light adaptation by ipRGCs appeared to be triggered by a Ca(2+) influx, in that the flash response elicited in the absence of extracellular Ca(2+) showed a normal rising phase but a slower decay phase, resulting in longer time to peak and higher sensitivity. There is, additionally, a prominent Ca(2+)-independent component of light adaptation not typically seen in rods and cones or in invertebrate rhabdomeric photoreceptors.
| S-EPMC3645585 | biostudies-literature
Project description:Intrinsically photosensitive retinal ganglion cells (ipRGCs) are rare mammalian photoreceptors essential for non-image-forming vision functions, such as circadian photoentrainment and the pupillary light reflex. They comprise multiple subtypes distinguishable by morphology, physiology, projections, and levels of expression of melanopsin (Opn4), their photopigment. The molecular programs that distinguish ipRGCs from other ganglion cells and ipRGC subtypes from one another remain elusive. Here, we present comprehensive gene expression profiles of early postnatal and adult mouse ipRGCs purified from two lines of reporter mice that mark different sets of ipRGC subtypes. We find dozens of novel genes highly enriched in ipRGCs. We reveal that Rasgrp1 and Tbx20 are selectively expressed in subsets of ipRGCs, though these molecularly defined groups imperfectly match established ipRGC subtypes. We demonstrate that the ipRGCs regulating circadian photoentrainment are diverse at the molecular level. Our findings reveal unexpected complexity in gene expression patterns across mammalian ipRGC subtypes.
| S-EPMC6712207 | biostudies-literature
Project description:Melanopsin photopigment expressed in intrinsically photosensitive retinal ganglion cells (ipRGCs) plays a crucial role in the adaptation of mammals to their ambient light environment through both image-forming and non-image-forming visual responses. The ipRGCs are structurally and functionally distinct from classical rod/cone photoreceptors and have unique properties, including single-photon response, long response latency, photon integration over time, and slow deactivation. We discovered that amino acid sequence features of melanopsin protein contribute to the functional properties of the ipRGCs. Phosphorylation of a cluster of Ser/Thr residues in the C-terminal cytoplasmic region of melanopsin contributes to deactivation, which in turn determines response latency and threshold sensitivity of the ipRGCs. The poorly conserved region distal to the phosphorylation cluster inhibits phosphorylation's functional role, thereby constituting a unique delayed deactivation mechanism. Concerted action of both regions sustains responses to dim light, allows for the integration of light over time, and results in precise signal duration.
| S-EPMC4891235 | biostudies-literature
Project description:Developing polyimide (PI) fibers with excellent interfacial adhesion and high mechanical properties for the PI fiber-reinforced polymer matrix composites (PFRPs) industry has been challenging. In this work, 4,4′-diamino-(1,1′-biphenyl)-3,3′-diol (HAB) diamine was introduced into the rigid molecular chains, and the high-performance PI fibers, presenting an interfacial shear strength (IFSS) value of 46.33 MPa, tensile strength of 2.62 GPa, and modulus of 100.15 GPa, were successfully manufactured when the content of HAB in mixed diamines was 30 mol %. Fourier transform infrared (FTIR) spectroscopy identified the presence of intermolecular H-bonding interactions, and 2D small-angle X-ray scattering indicated that the introduction of HAB moiety contributed to reducing the radii of microvoids in the fibers, which were considered to be the key factors leading to a significant enhancement in the mechanical properties of the fibers. X-ray photoelectron spectroscopy (XPS) and the static contact angle intuitively illustrated that the synthetic fiber surface contained active hydroxyl groups. The IFSS value of PI fiber/epoxy resin composites (PI/EPs) was 56.47 MPa when the content of HAB reached 70 mol %. Failure morphologies confirmed that the interfacial adhesion of PI/EPs was enhanced owing to the surface activity of PI fibers. Consequently, this study provides an effective strategy to the long-standing problems of high mechanical performances and poor surface activity for traditional PI fibers used in the PFRPs industry.
| S-EPMC9967378 | biostudies-literature