Surface Disorder Research Articles

Evaluating plasma assisted noninvasive surgery (PANIS) as a new method for pterygium removal; a clinical case series

Purpose: The present study aimed to evaluate the outcomes of a new technique for pterygium surgery using a plasma-based method. Methods: A clinical case series study was carried out in 6 patients. Six eyes with grade 2 or 3 of primary pterygium were operated. The pterygium head was detached from the corneal surface. Then, the free conjunctival edges were attached near the limbus using the plasma spots [generated by Plexr device (GMV, Rocca Priora, RM, Italy)]. Refractive Error (RE), Visual Acuity (VA), Intraocular Pressure (IOP), Contrast Sensitivity (CS), Corneal Fluorescein Staining (CFS), Tear Meniscus Height (TMH), High Order Aberrations (HOA), and Ocular Surface Disorder Index (OSDI) were measured before the operation, one week after the operation, as well asone, three, and six months post-surgery. Slit-lamp images were taken before surgery and six months after that. Results: No intraoperative and postoperative complications were observed. Mild degrees of pain, tearing, foreign body sensation, and irritation was reported during the first week after surgery. No significant change was found in IOP, CS, and TMH parameters during the 6-month follow-up. A slight improvement was measured in CFS and HOA after surgery. Compare to before surgery, RE, VA, and OSDI improved after pterygium removal. The follow-up examinations revealed pterygium recurrence in 2 eyes. Conclusion: Our results showed that plasma-assisted noninvasive surgery can provide a simple, fast, and effective techniquefor pterygium removal with no suture or glue. Although, considering the two observed recurrences in this study, we decided to modify the surgical method in the subsequent studies. Keywords: pterygium; treatment; plasma; noninvasive surgery; case series.

Fungal corneal ulcer in a 27 weeks primigravida with anemia and multi-vitamin deficiency

Fungal keratitis is an infection of the cornea which can lead to severe visual compromise if not diagnosed on time and managed appropriately. It may present with minimal symptoms and many signs. Likely to be overlooked by the patient, it results in a late presentation when substantial damage has already occurred. It is usually seen in patients with a severe immune compromise such as acquired immunodeficiency syndrome (AIDS), uncontrolled diabetes, transplant patients on immune-suppressants or long-term steroids, and in pre-existing ocular surface disorder. This is a case report of a 27-week primigravida who presented with extreme fatigue and a fungal corneal ulcer with no preceding history of trauma or any other immune compromised state.

Single-Crystal Alkali Antimonide Photocathodes: High Efficiency in the Ultrathin Limit.

The properties of photoemission electron sources determine the ultimate performance of a wide class of electron accelerators and photon detectors. To date, all high-efficiency visible-light photocathode materials are either polycrystalline or exhibit intrinsic surface disorder, both of which limit emitted electron beam brightness. In this Letter, we demonstrate the synthesis of epitaxial thin films of Cs_{3}Sb on 3C-SiC (001) using molecular-beam epitaxy. Films as thin as 4nm have quantum efficiencies exceeding 2% at 532nm. We also find that epitaxial films have an order of magnitude larger quantum efficiency at 650nm than comparable polycrystalline films on Si. Additionally, these films permit angle-resolved photoemission spectroscopy measurements of the electronic structure, which are found to be in good agreement with theory. Epitaxial films open the door to dramatic brightness enhancements via increased efficiency near threshold, reduced surface disorder, and the possibility of engineering new photoemission functionality at the level of single atomic layers.

Changes in tear film parameters after manual small incision cataract surgery

Dry eye disease is an ocular surface disorder leading to tear film instability. Causes are multifactorial, cataract surgery being one of its causes. To evaluate changes in the tear film parameters (Schirmer’s I, Schirmer’s II and tear film breakup time) and to find out the factors influencing it following manual small incision cataract surgery.: A prospective observational study was carried out in 185 eyes of 185 patients aged ≥50 years with age related cataract without preoperative dry eye. All the patients were evaluated for the changes in the tear film parameters at prior to the study and post operative day 7, one month and at 3 months. Dry eye was predominantly seen in males (96, 51.89%). Majority of the patients were in the age groups 50-60 years (84, 45.4%). Dry eye was seen in 7% of patients. Majority had mild grade dry eyes (50, 79%). There was decline in the all tear film parameters peaked at seventh day followed by gradual increasing trend over one month till the last follow up. Statistically significant changes was seen in all the tear film parameters between preoperative and post operative visits (p<0.001). Development of dry eye was correlated with older age, diabetes mellitus and duration of microscope light exposure time. Manual small incision cataract surgery can induce decline in tear film values in early post operative period with gradually increasing trend over time. Majority of patients had mild grade dry eyes.

Structural degradation of graphite anode induced by dissolved manganese ions in lithium-ion batteries

Manganese (Mn) species deposited on anodes have been identified as one of the primary sources of capacity and power fading in Li-ion batteries (LIBs). Previous studies have overwhelmingly focused on the effect of Mn species present on the anode surface on the electrochemical performance of LIBs and their relation to chemical degradation of the solid electrolyte interphase (SEI). This study investigates the role of Mn ions dissolved in electrolytes in the structural degradation of a graphite anode. X-ray diffraction results find evidence for the hypothesis that dissolved Mn ions could co-intercalate into the graphite structure at an early stage of the Li-ion intercalation. Furthermore, Raman spectroscopy results demonstrate severe local surface disordering of graphite in the presence of Mn ions. Calculations based on density functional theory (DFT) support the experimental findings, revealing that Mn co-intercalated into the graphite structure inhibits the expansion of the graphite interlayers upon Li-ion intercalation. Results from this study provide new insights into the current mechanisms of the degradation of manganese-based cathode–graphite battery cells. The proposed mechanism of graphite structural degradation induced by Mn ions can help researchers and engineers design LIBs with longer lifespans.

Hydrogen absorption and diffusion behaviors in cube-shaped palladium nanoparticles revealed by ambient-pressure X-ray photoelectron spectroscopy

The hydrogen absorption and diffusion processes in cube-shaped palladium (Pd) nanoparticles (NPs) were studied by the combination of ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) and density functional theory (DFT) calculations. A size dependence of the subsurface hydrogen absorption was observed. More hydrogen atoms were absorbed in the subsurface of the smaller-sized Pd NPs owing to the enhancement of the diffusivity of H atoms from the surface into the subsurface rather than the adsorption or absorption rates at the initial stages. This results from the weakened Pd-H bond caused by surface disordering of Pd NPs with the reduction of the size of the particles. Furthermore, we discuss the H absorption sites in the bulk by comparing the relative Pd 3d core-level binding energy shifts of the Pd atoms obtained from the AP-XPS results and the theoretical calculations. The octahedral (O) sites are shown to be more favorable than the tetrahedral (T) sites for hydrogen occupation by comparing the experimental results and theoretical calculations. Finally, we proposed an interaction model between hydrogen and the Pd NPs during H2 absorption and diffusion to provide new insights into the hydrogen absorption process.

Impact on nonlinear/linear optical and structural parameters in quaternary In15Ag10S15Se60 thin films upon annealing at different temperatures

In the present study, the effect of thermal annealing on structural, linear, and nonlinear optical properties of quaternary chalcogenide In15Ag10S15Se60 thin film has been reported. The bulk sample synthesized by the melt quenching technique was used for the thin film preparation by the thermal evaporation method. Post deposition, the thin films were annealed at different temperatures like 100 °C, 150 °C, 200 °C, and 250 °C for 2 hs. X-ray diffraction (XRD) and Raman spectroscopy were used for structural studies, which showed the increase in crystalline phases with the increase of annealing temperature. The morphological images taken by field emission scanning electron microscope (FESEM) showed the densification and enlargement of scattered grains for annealed films. Furthermore, the constituent elements and their percentage in the sample were confirmed by Energy dispersive X-ray analysis (EDX). The linear and nonlinear optical parameters were calculated from the transmittance data obtained from UV–Vis spectroscopy in the wavelength range of 600–1100 nm. There is a large reduction in third-order nonlinear susceptibility at the higher annealing temperature. Subsequently, the transmission increased, whereas the absorption decreased with the annealing temperature. The extinction coefficient decreased while there was an increase in optical bandgap for the annealed films due to the decrease in surface defects and disorder, which forms the localized states in the bandgap. The oscillator energy, dispersion energy, dielectric constant, optical conductivity were calculated and discussed in detail. The change in both linear and nonlinear parameters by thermal annealing could be useful for controlling the optical properties of In15Ag10S15Se60 thin film, which could be the preferable candidate for numerous photonic applications.

Deformation characteristics of nanolayered dual-phase CrCoNi medium-entropy alloy nanowires

Due to the potential excellent mechanical properties of multicomponent alloys, the design of their microstructures and deformation mechanisms have attracted considerable attention. In this work, using molecular dynamics simulations, the mechanical behaviors of nanolayered face-centered cube/hexagonal close-packed (FCC/HCP) dual-phase CrCoNi medium-entropy alloys (MEAs) were investigated. The mechanical behaviors of the nanolayered dual-phase nanowires with various radii were studied and the effects of nanolayered dual-phase structure were evaluated. It was found that there are two different deformation modes mainly related to the dislocation nucleation position in the FCC phase or the HCP phase, of which in Model I dislocations nucleate from the intersection of phase boundary and surface, while in Model II dislocations nucleate on the surface of HCP phase. The deformation mode and strength change periodically with the variation of the surface disorder degree against radius. Annealing in the temperature range of 600–800 K can optimize the dual-phase structure, change the deformation mode and improve the mechanical performance.

Tuneable electron\u2013magnon coupling of ferromagnetic surface states in PdCoO2

Controlling spin wave excitations in magnetic materials underpins the burgeoning field of magnonics. Yet, little is known about how magnons interact with the conduction electrons of itinerant magnets, or how this interplay can be controlled. Via a surface-sensitive spectroscopic approach, we demonstrate a strong electron–magnon coupling at the Pd-terminated surface of the delafossite oxide PdCoO2, where a polar surface charge mediates a Stoner transition to itinerant surface ferromagnetism. We show how the coupling is enhanced sevenfold with increasing surface disorder, and concomitant charge carrier doping, becoming sufficiently strong to drive the system into a polaronic regime, accompanied by a significant quasiparticle mass enhancement. Our study thus sheds light on electron–magnon interactions in solid-state materials, and the ways in which these can be controlled.

Characterization of the Cellular Microenvironment and Novel Specific Biomarkers in Pterygia Using RNA Sequencing.

With a worldwide prevalence of ~12%, pterygium is a common degenerative and environmentally triggered ocular surface disorder characterized by wing-shaped growth of conjunctival tissue onto the cornea that can lead to blindness if left untreated. This study characterizes the transcriptional profile and the cellular microenvironment of conjunctival pterygia and identifies novel pterygia-specific biomarkers. Formalin-fixed and paraffin-embedded pterygia as well as healthy conjunctival specimens were analyzed using MACE RNA sequencing (n = 8 each) and immunohistochemistry (pterygia n = 7, control n = 3). According to the bioinformatic cell type enrichment analysis using xCell, the cellular microenvironment of pterygia was characterized by an enrichment of myofibroblasts, T-lymphocytes and various antigen-presenting cells, including dendritic cells and macrophages. Differentially expressed genes that were increased in pterygia compared to control tissue were mainly involved in autophagy (including DCN, TMBIM6), cellular response to stress (including TPT1, DDX5) as well as fibroblast proliferation and epithelial to mesenchymal transition (including CTNNB1, TGFBR1, and FN1). Immunohistochemical analysis confirmed a significantly increased FN1 stromal immunoreactivity in pterygia when compared to control tissue. In addition, a variety of factors involved in apoptosis were significantly downregulated in pterygia, including LCN2, CTSD, and NISCH. Furthermore, 450 pterygia-specific biomarkers were identified by including transcriptional data of different ocular surface pathologies serving as controls (training group), which were then validated using transcriptional data of cultured human pterygium cells. Among the most pterygia-specific factors were transcripts such as AHNAK, RTN4, TPT1, FSTL1, and SPARC. Immunohistochemical validation of SPARC revealed a significantly increased stromal immunoreactivity in pterygia when compared to controls, most notably in vessels and intravascular vessel wall-adherent mononuclear cells. Taken together, the present study provides new insights into the cellular microenvironment and the transcriptional profile of pterygia, identifies new and specific biomarkers and in addition to fibrosis-related genes, uncovers autophagy, stress response and apoptosis modulation as pterygium-associated processes. These findings expand our understanding of the pathophysiology of pterygia, provide new diagnostic tools, and may enable new targeted therapeutic options for this common and sight-threatening ocular surface disease.

Rapid 3D bioprinting of a multicellular model recapitulating pterygium microenvironment

Pterygium is an ocular surface disorder with high prevalence that can lead to vision impairment. As a pathological outgrowth of conjunctiva, pterygium involves neovascularization and chronic inflammation. Here, we developed a 3D multicellular in vitro pterygium model using a digital light processing (DLP)-based 3D bioprinting platform with human conjunctival stem cells (hCjSCs). A novel feeder-free culture system was adopted and efficiently expanded the primary hCjSCs with homogeneity, stemness and differentiation potency. The DLP-based 3D bioprinting method was able to fabricate hydrogel scaffolds that support the viability and biological integrity of the encapsulated hCjSCs. The bioprinted 3D pterygium model consisted of hCjSCs, immune cells, and vascular cells to recapitulate the disease microenvironment. Transcriptomic analysis using RNA sequencing (RNA-seq) identified a distinct profile correlated to inflammation response, angiogenesis, and epithelial mesenchymal transition in the bioprinted 3D pterygium model. In addition, the pterygium signatures and disease relevance of the bioprinted model were validated with the public RNA-seq data from patient-derived pterygium tissues. By integrating the stem cell technology with 3D bioprinting, this is the first reported 3D in vitro disease model for pterygium that can be utilized for future studies towards personalized medicine and drug screening.

Pterygium

Pterygium, also known as surfer’s eye, is a common ocular surface disorder originating in the limbal conjunctiva within the palpebral fissure with progressive involvement of the cornea. The fibrovascular lesion occurs more often at the nasal limbus than the temporal limbus, adopting a characteristic wing-like appearance. In this article we will discuss the presentation of pterygium, its underlying pathophysiology and the diagnostic steps taken by clinicians to recognise pterygium as well as the management of these patients.

The synthesis of Au-NPs by ion implantation in the crystalline GaN and characterisation of their optical properties

Nanostructured surfaces with embedded noble metal nanoparticles is an attractive way for manipulation with the optical properties of wide bandgap semiconductors applied in optoelectronics, photocatalytic processes or for Surface-Enhanced Raman spectroscopy. Ion implantation offers an effective way for nanoparticle preparation without the use of additional chemicals that offers precise control of nanoparticle depth distribution. The aim of this study is a synthesis of the gold nanoparticles in GaN by implantation of 1.85 MeV Au ions with high fluences up to 7×1016 cm-2 and study of optical properties of Au implanted GaN. Implanted crystals were annealed at 800 °C in an ammonia atmosphere for 20 min to support Au nanoparticle creation and GaN recovery. The structure characterisation has been realized by Rutherford backscattering spectroscopy in channelling mode and it showed the formation of two separated disordered regions – the surface region and buried layer. The lower implantation fluences induce damage mainly in a buried layer; however, the increase of the Au-ion fluence leads to the increase of surface disorder as well. Further, the increase of the Au-ion fluence induces the Au dopant shift to the surface and multimodal Audepth profiles. TEM analyses confirmed the formation of Au nanoparticles in the implanted samples after annealing with sizes up to 14 nm. The increase of light absorption and modification of GaN bandgap of the Au modified GaN was deduced from the change in optical transmission spectra between 370 – 1400 nm.

Strengthening Cellulose Nanopaper via Deep Eutectic Solvent and Ultrasound-Induced Surface Disordering of Nanofibers.

The route for the preparation of cellulose nanofiber dispersions from bacterial cellulose using ethylene glycol- or glycerol-based deep eutectic solvents (DES) is demonstrated. Choline chloride was used as a hydrogen bond acceptor and the effect of the combined influence of DES treatment and ultrasound on the thermal and mechanical properties of bacterial cellulose nanofibers (BC-NFs) is demonstrated. It was found that the maximal Young’s modulus (9.2 GPa) is achieved for samples prepared using a combination of ethylene glycol-based DES and ultrasound treatment. Samples prepared with glycerol-based DES combined with ultrasound exhibit the maximal strength (132 MPa). Results on the mechanical properties are discussed based on the structural investigations that were performed using FTIR, Raman, WAXD, SEM and AFM measurements, as well as the determination of the degree of polymerization and the density of BC-NF packing during drying with the formation of paper. We propose that the disordering of the BC-NF surface structure along with the preservation of high crystallinity bulk are the key factors leading to the improved mechanical and thermal characteristics of prepared BC-NF-based papers.

SUTURELESS AND GLUE FREE CONJUNCTIVAL AUTOGRAFT (CAG) IN PTERYGIUM SURGERY WITH AUTOLOGOUS BLOOD SERUM VS BARE SCLERA TECHNIQUE.

Introduction: Pterygium is a common ocular surface disorder. The pathognomonic feature is elastotic degeneration of conjunctival stroma, and, an excessive bro-proliferative reaction. Aim: To compare and analyze the surgical outcome of pterygium excision followed by sutureless glue-free CAG with autologous blood serum vs bare sclera technique. Study Design: Prospective, Randomized control study. Materials & Methods: 32 eyes of 32 patients with primary Pterygium were selected. Ptrygium excision with Conjunctival autograft and in other group bare sclera was done and results were compared. Post-operative course were followed for 12 months after surgery. Inclusion Criteria:We included patients of all ages and gender with primary pterygium of different grades viz. grade 1, grade 2 and grade 3.We did not included temporal pterygium in our research study, as it is rare to occur. Exclusion Criteria: Glaucoma, recurrent pterygium, retinal pathology requiring surgical intervention, patients with history of previous ocular surgery or history of scleritis, Pseudo-pterygium, HIV/hepatitis B. Discussion: The standard treatment for pterygium is; excision followed by CAG. Results: Pterygium excision followed by CAG with autologous blood serum is better and recurrence rate is nil to minimal than with bare sclera technique. Conclusion: Sutureless, glue-free pterygium excision with CAG is effective, safe and cosmetically better option for management of primary pterygium also, it showed lesser recurrence rate.

Ayurvedic Management of Severe Dry Eye Syndrome & Complications: A Case Study

Dry eye syndrome (DES) is a common condition that causes pain and can lead to vision problems. Modern living has given rise to a massive increase in the incidence of vision threatening dry eye disease, around 10-30% of population living in industrialized countries suffer from dry eye syndrome (DES). According to Second International Dry Eye Workshop (DEWS II) in 2017 offered dry eye as it is a multifactorial ocular surface disorder defined by a loss of tear film homeostasis and ocular symptoms, in which tear film instability and hyperosmolarity, as well as ocular surface inflammation and injury, play a part in the etiology. If it is not controlled with in time it can lead to corneal blindness. Ayurveda proposes a comprehensive systemic & topical strategy in the treatment of dry eye syndrome, in contrast to the available modern medical treatment. In this publication, a case study of a Shushkakshipaka with many complications who was treated with dynamic Ayurvedic treatments & after continuous efforts patient got very significant results is being discussed here.

Atomic Disorder Enables Superior Catalytic Surface of Pt-Based Catalysts for Alkaline Hydrogen Evolution

Crystalline Pt catalyst for alkaline hydrogen evolution reaction (HER) catalysis is essentially hindered by the slow water dissociation kinetics, originated from the almost full-filled d orbitals and limited numbers of the coordination-unsaturated sites. Breaking the symmetrical atomic arrangements is theoretically feasible to solve this issue, but technically challenging. Herein, surface-disordered Pt–Ni nanowires (d-Pt–Ni NWs) are synthesized via a lithiation/delithiation method. The d-Pt–Ni NWs exhibit an ultralow overpotential of 15 mV at 10 mA cm–2 for HER catalysis, substantially superior to the crystalline counterpart and commercial Pt/C. Fine structural analyses reveal that the structural disorder can well regulate the electronic structures of Pt–Ni and the generated oxygenated nickel species contribute to stabilize the disordered structures. Furthermore, theoretical studies unravel that the oxygenated nickel with lower unoccupied orbitals helps facilitate water dissociation, while the upshift of the d band center of Pt enables superior H adsorption. More importantly, surface disordering is finally demonstrated to be a universal strategy to boost the HER activities of Pt-based alloys. Manipulating the surface atomic arrangement offers a new opportunity to design and optimize Pt-based catalysts and beyond.

High efficiency planar perovskite solar cell by surface disorder removal on mesoporous tin oxide

Tin oxide (SnO2) is widely used in perovskite solar cells (PSCs) as an electron transport layer (ETL) material. Ethanol usually serves as a solvent of ETL but no one discussed the possible influences caused by ethanol. In this work, the effects of ethanol were investigated systematically. It is clear that ethanol treatment (EtOH-SnO2) can remove surface disorder of mesoporous SnO2 and thus enhance the conductivity as well. As a result, the champion PCE of 21.62% is obtained in PSC with EtOH-SnO2 ETL, which is higher than that of control device (20.70%) due to improved film quality. Meanwhile, compared with control PSCs, the stability of the perovskite layer deposited on EtOH-SnO2 ETL is gradually improved both for the light and thermal stability. Therefore, we make clear that the ethanol treatment can improve the quality of mesoporous SnO2 and perovskite films for optoelectronic device.

Corynebacterium Keratitis: Pure Versus Mixed Infection and Antibiotic Susceptibility Patterns From Different Tertiary Eye Care Centers.

The objective of this study was to compare the clinical and microbiological profiles of culture-proven pure Corynebacterium keratitis with mixed infection and their antibiotic susceptibility patterns over a 2-year period. A retrospective analysis of culture-proven cases of Corynebacterium keratitis over a 2-year period was performed in 3 different tertiary eye care centers. All isolates were tested for antibiotic susceptibility in vitro using the disc-diffusion method for 7 antibiotics. Altogether 108 cases were identified as culture-positive Corynebacterium keratitis in 3 tertiary eye care centers. Of these, 60.2% (n = 65) and 39.8% (n = 43) of cases were due to pure Corynebacterium and mixed infection, respectively. The mean duration of symptoms was 23.2 ± 29.6 days. In the mixed-infection group, fungus was identified as the coexistent pathogen in 22 cases (51.1%). Ocular surface disorder was the most common risk factor (33.9%) in Corynebacterium keratitis. The most frequently isolated species was Corynebacterium amycolatum (22.2%) in both groups. Therapeutic keratoplasty was performed in 8.3% of cases. There was no significant difference in the outcome between the 2 groups. Cefazolin resistance was seen in 13.9% of patients, and all isolates were susceptible to vancomycin. The resistance pattern showed emerging resistance toward fluoroquinolone because the isolates were resistant to gatifloxacin (58.3%), moxifloxacin (47.2%), ciprofloxacin (54.6%), and ofloxacin (45.4%). Ocular surface disorder is the most common risk factor in Corynebacterium keratitis. Although fluoroquinolones are commonly used as first-line therapy in microbial keratitis, the in vitro resistance pattern indicates that these are less likely to be effective in infection with Corynebacterium species.

Spontaneous dynamical disordering of borophenes in MgB2 and related metal borides

Layered boron compounds have attracted significant interest in applications from energy storage to electronic materials to device applications, owing in part to a diversity of surface properties tied to specific arrangements of boron atoms. Here we report the energy landscape for surface atomic configurations of MgB2 by combining first-principles calculations, global optimization, material synthesis and characterization. We demonstrate that contrary to previous assumptions, multiple disordered reconstructions are thermodynamically preferred and kinetically accessible within exposed B surfaces in MgB2 and other layered metal diborides at low boron chemical potentials. Such a dynamic environment and intrinsic disordering of the B surface atoms present new opportunities to realize a diverse set of 2D boron structures. We validated the predicted surface disorder by characterizing exfoliated boron-terminated MgB2 nanosheets. We further discuss application-relevant implications, with a particular view towards understanding the impact of boron surface heterogeneity on hydrogen storage performance.