Confocal Optical Microscopy Research Articles

Low-temperature ozone treatment for p-xylene perm-selective MFI type zeolite membranes: Unprecedented revelation of performance-negating cracks larger than 10 nm in polycrystalline membrane structures

We report that low-temperature ozone calcination allowed MFI type polycrystalline zeolite membranes to maximize their p-/o-xylene separation factor (as high as ca. 2000) by suppressing defect formation. Conventional high-temperature calcination and rapid thermal processing, which provide poor and marked p-/o-xylene separation abilities, respectively, were used for comparison. The corresponding defect structures were quantitatively analyzed by image processing of fluorescence confocal optical microscopy images combined with membrane permeation modeling, revealing the main defects (grain boundary defects and cracks) and their tortuosity, porosity, and size. To the best of our knowledge, we, for the first time, demonstrated that in contrast to common belief, the minor portion of wider cracks instead of the major portion of narrower grain boundary defects determined the final permeation rates. Specifically, the MFI membrane prepared by high-temperature calcination contained many grain boundary defects (narrow; ca. 1 nm) and few cracks (wide; ca. 20 nm) that accounted for ca. 0.1% and 99.8%, respectively, of the slowly permeating o-xylene molar flux. In contrast, the ozone-treated MFI membranes, which only possessed grain boundary defects, achieved the high p-/o-xylene separation performance, underlining the need for the selective reduction in the number of wider cracks rather than ubiquitous, narrow grain boundary defects.

A facile method for fabricating super-slippery surface with long term and high-efficiency sustained release performance

Slippery liquid infused porous surfaces (SLIPS) process potential applications in surface liquid repellency, self-cleaning and anti-adhesion, while exhibiting long-term and stable release of lubricants is remaining a great challenge. Herein, an efficient liquid injection method was proposed to construct SLIPS by altering the surface energy and adjusting the inner porous structure using the facile method of direct UV irradiation. The infusion efficiency and release behavior were significantly improved and verified with various techniques such as wetting measurement, confocal fluorescence microscopy and optical microscopy. It was found that the infusion and release behavior of lubricants were varied for different specimens with different UV irradiation time. Compared to the prime substrate, PDMS treated with 90 min UV irradiation showed the highest volume of lubricant penetration which was increased almost by 833 %. Additionally, the amount of infusion consisted with the surface energy and specimens with moderate wetting exhibited the most effective lubricating performance. For the sample with 90 min UV irradiation, an ultra-low friction coefficient of 0.018 was observed under water lubrication and its releasing could be detected even after a long period of 768 h. Our results provided a facile method for the future development of long-term lubricating surfaces which may broaden their applications in fields of anti-corrosion, anti-icing and anti-fog, anti-fouling, micro-flow control and oil-water ultra-slippery occasions.

Surface characterization of indirect restorative materials submitted to different etching protocols

ObjectivesThis in vitro study aimed to evaluate the effect of different times and concentrations of hydrofluoric acid etching on the surface of indirect restorative materials obtained from blocks used in CAD-CAM technology. MethodsSpecimens (4 mm × 4 mm × 0.8 mm) were obtained for each indirect restorative material: zirconia-reinforced lithium monosilicate ceramic (Celtra Duo), nanoceramic resin (Lava Ultimate), and polymer-infiltrated ceramic network material (Vita Enamic). The materials were submitted to etching with 5% or 10% hydrofluoric acid for 20, 40, 60, or 90 s. A control group for each material was evaluated without any surface treatment, totaling nine experimental groups for each material (n = 10). The specimens were evaluated for surface roughness (Ra and Rz), confocal optical microscopy, the contact angle (θ), surface free energy (γs), total free interaction energy (∆G) using a goniometer, and microshear bond strength to resin cement. Specimen images were obtained using scanning electron microscopy, confocal optical microscopy, and atomic force microscopy. Data on the surface roughness, the contact angle, surface free energy, total free interaction energy, and bond strength were subjected to two-way ANOVA and Tukey´s test (α=0.05). ResultsIn general, Celtra Duo showed better results after etching with 10% hydrofluoric acid for 40 or 60 s. Lava Ultimate showed better performance after etching with 10% hydrofluoric acid for 20 or 40 s, whereas Vita Enamic showed better results after etching with 5% hydrofluoric acid for 90 s. ConclusionEach material showed different characteristics after etching with hydrofluoric acid. Knowledge of the proper protocol for each material is essential to ensure improvements in the adhesion process and durability of indirect restorations. In general, Celtra Duo presented mechanical properties superior to those of Lava Ultimate and Vita Enamic. Clinical SignificanceSpecific etching protocols must be recommended for each indirect material because longer exposure to hydrofluoric acid can jeopardize the surface, thus affecting the mechanical and bond strength properties.

Confocal Fluorescence Microscopy to Probe in Operando electrochemical Conversion

The development of electrochemical devices, such as flow batteries, fuel cells and electrolysers, is critical for the transition to a sustainable economy. Given the critical role of porous electrodes in the performance of these devices, understanding their structure-function relationship is crucial. Although porous electrodes with many different internal structures have been utilized, there is no clear consensus as to what features lead to what aspects of electrode performance. Transport in porous electrodes is commonly approximated by mean-field theories, which assumes a homogenous, Darcy-like permeability in the porous structure. Recent findings have challenged the suitability of these assumptions by revealing extreme heterogeneities in the electrolyte transport, on commercially relevant length scales exceeding the electrode pore size by an order of magnitude. [1]In this study, we introduce a new analytical method for electrochemical flow devices: 4D Confocal Optical Fluorescence Microscopy. This non-invasive in-situ analytical technique distinguishes between oxidized and reduced molecular species by their fluorescence spectra and maps out 3D molecular concentration fields with single-digit micron resolution (Figure 1). 3D movies, correlated with macroscopic chronoamperometry, add time as a fourth dimension. Thus, electrochemical conversion and species advection and diffusion can be monitored at heretofore unprecedented resolution, giving us new routes to understanding local phenomena in porous electrodes. We demonstrate this method by monitoring the reversible electrolytic reduction of 2,7 anthraquinone disulfonate (AQDS) to its corresponding hydroquinone, H2AQDS, in aqueous electrolyte in a transparent electrochemical cell. We monitor changes in the concentration field as a response to the variation of applied potential and current in real time. We correlate the fluorescence intensity of a particular band of wavelengths to the electrolyte state of charge. Furthermore, high sensitivity to non-linear optical effects enables us to capture the reversible formation of a dimer, specific to the AQDS/H2AQDS system, quantitatively in an operating battery.This new high-resolution 4D technique of characterizing operando electrochemical devices is expected to provide insight into the relationship between electrode microstructure and electrochemical performance features.Literature cited:[1] A.A. Wong, S.M. Rubinstein and M.J. Aziz, “Direct visualization of electrochemical reactions and heterogeneous transport within porous electrodes in operando by fluorescence microscopy” Cell Reports Phys. Sci. 2021, 100388; https://doi.org/10.1016/j.xcrp.2021.100388 Figure 1

Experimental Observation of ABCB Stacked Tetralayer Graphene.

In tetralayer graphene, three inequivalent layer stackings should exist; however, only rhombohedral (ABCA) and Bernal (ABAB) stacking have so far been observed. The three stacking sequences differ in their electronic structure, with the elusive third stacking (ABCB) being unique as it is predicted to exhibit an intrinsic bandgap as well as locally flat bands around the K points. Here, we use scattering-type scanning near-field optical microscopy and confocal Raman microscopy to identify and characterize domains of ABCB stacked tetralayer graphene. We differentiate between the three stacking sequences by addressing characteristic interband contributions in the optical conductivity between 0.28 and 0.56 eV with amplitude and phase-resolved near-field nanospectroscopy. By normalizing adjacent flakes to each other, we achieve good agreement between theory and experiment, allowing for the unambiguous assignment of ABCB domains in tetralayer graphene. These results establish near-field spectroscopy at the interband transitions as a semiquantitative tool, enabling the recognition of ABCB domains in tetralayer graphene flakes and, therefore, providing a basis to study correlation physics of this exciting phase.

Computational investigation of incident ion angles and material erosion at rough graphite and silicon carbide divertor surfaces

We present a computational investigation of the dependence of material erosion on the incident ion angle at rough graphite and silicon carbide divertor surfaces. Ion angle distributions (IADs) for D plasmas at NSTX-U and DIII-D divertors were calculated by an equation-of-motion model that traces the ion trajectories in the sheath. Then, the effective sputtering yields and ion shadowed area fractions were calculated by a Monte Carlo micro-patterning and roughness code that applied the calculated IADs to surface topographic data that were obtained from optical confocal microscopy of rough graphite and SiC divertor surfaces from NSTX-U and DIII-D experiments. The calculations found that the effective sputtering yields, the sputtering pattern, and the shadowed area are determined by the detailed surface topology rather than the root mean square roughness RRMS, which represents deviations from a flat surface. The suppression of the effective sputtering yields for rough surfaces compared to the yield for a smooth surface was accounted for by the change of the mean local incident ion angle (LIIA) ⟨θ′⟩. The mean surface inclination angle distribution (SIAD) ⟨δ⟩ was found to be a useful parameter to estimate the LIIA from the calculated IADs. We report global empirical formulas for the mean LIIA and fraction of the area shadowed from the main ions for D plasmas for rough surfaces with B-field incident angles α = 85°–89° as a function of the mean SIAD ⟨δ⟩. We propose the use of the mean LIIA ⟨θ′⟩ to estimate the sputtering yield for rough surfaces from the angular dependence of the sputtering yield.

Deep learning alignment of bidirectional raster scanning in high speed photoacoustic microscopy

Simultaneous point-by-point raster scanning of optical and acoustic beams has been widely adapted to high-speed photoacoustic microscopy (PAM) using a water-immersible microelectromechanical system or galvanometer scanner. However, when using high-speed water-immersible scanners, the two consecutively acquired bidirectional PAM images are misaligned with each other because of unstable performance, which causes a non-uniform time interval between scanning points. Therefore, only one unidirectionally acquired image is typically used; consequently, the imaging speed is reduced by half. Here, we demonstrate a scanning framework based on a deep neural network (DNN) to correct misaligned PAM images acquired via bidirectional raster scanning. The proposed method doubles the imaging speed compared to that of conventional methods by aligning nonlinear mismatched cross-sectional B-scan photoacoustic images during bidirectional raster scanning. Our DNN-assisted raster scanning framework can further potentially be applied to other raster scanning-based biomedical imaging tools, such as optical coherence tomography, ultrasound microscopy, and confocal microscopy.

Correlative multimodal imaging and targeted lasering for automated high-precision IC decapsulation

Performing failure analysis, circuit edits, and quality control checks on microelectronics calls for the ability to reliably decapsulate these devices. Existing methods for decapsulation suffer from multiple challenges, including but not limited to unpredictable process variations, damage to the bond wires and the die, lack of a systematic and reliable workflow, high dependence on the operator and lack of automation. To address these challenges, we propose a correlative workflow that combines multimodal imaging and targeted lasering for automated, high precision decapsulation of integrated circuits (ICs). A femtosecond laser system is used for high-throughput, high-precision, athermal material removal. X-ray computed tomography is used for acquiring a high-resolution guide map for material removal, non-destructively. Optical and laser confocal microscopy are used for monitoring the procedure and providing feedback to the lasering component. Scanning electron microscopy is used for final verification of the decapsulation outcome, in combination with in situ bond wire pull testing. We show the application of proposed workflow for decapsulation of three ICs.

Surface finishing effects on the corrosion behavior and electrochemical activity of 2098-T351 aluminum alloy investigated using scanning microelectrochemical techniques

The effects of surface finishing on the corrosion behavior and electrochemical activity of AA2098-T351 (Al–Cu–Li alloy) were investigated on the basis of the correlation between surface chemistry, microstructure and electrochemical activity. The alloy was evaluated in the as-received and polished conditions. The morphology of the two types of surfaces was investigated using confocal laser scanning microscopy (CLSM), optical microscopy and optical 3D profilometry. The surface chemistry was analyzed by X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX). Scanning microelectrochemical techniques (namely, localized electrochemical impedance spectroscopy (LEIS), the scanning vibrating electrode technique (SVET) and scanning electrochemical microscopy (SECM) in potentiometric mode) were used to examine the electrochemical activity of the surfaces. The results showed that on the as-received surface, the near surface deformed layer (NSDL), which is composed of Mg-rich bands, influenced the corrosion activity of the alloy. Higher electrochemical activity and greater susceptibility to severe localized corrosion were related to the polished surface condition compared to the as-received one. • Surface finishing effects on chemical activity of 2098-T351 Al–Cu–Li alloy studied using scanning microelectrochemical techniques. • The effect of the near-surface deformed layer (NSDL) on 2098-T351 Al–Cu–Li was investigated for different surface finishes. • A solid contact magnesium ion-selective microelectrode (Mg 2+ ISME) employed to monitor Mg 2+ distributions over the surfaces. • SVET, LEIS, and SECM in potentiometric operation produced high spatial resolution images of reactive sites on the surfaces. • The surface chemistry, microstructure and electrochemical activity of the alloy with and without NSDL were correlated.

Superficial bladder cancer diagnosis — the deliberate choice between fluorescent diagnosis and optical biopsy

Bladder carcinoma in situ (CIS) is a potentially invasive tumor whose early detection is a key step to ensuring the preservation of the bladder, reducing mortality, and improving the quality of patients’ life. The early diagnosis of bladder cancer requires a sensitive technique that can detect the lesion to determine its stage and grade. ALA induced-PpIX makes it possible to detect tumors with 90% sensitivity. ALA hexyl ester (hALA) increases the sensitivity to 95%. Macroscopic techniques require a histological biopsy to define the tumor invasiveness. Imaging with Fibered Optic Confocal Fluorescence Microscopy allows the optical sectioning of examined tissues providing images with subcellular resolution after labeling with adequate fluorescent dye chosen based on the sensitivity of the used device. Available fluorescent agents are compatible with used devices; however, their toxicity and mutagenesis studies are unsatisfactory. During imaging, an optical fiber is introduced into the bladder via the urethra and placed in contact with the bladder wall. The distinction between the different types of epithelial cells is based on the cell size, morphology, and signal intensity. Although not fully adopted for clinical application, the FOCM represents a real asset that reduces invasiveness and complements the fluorescence-based endoscopy.

Mirau-based line-field confocal optical coherence tomography for three-dimensional high-resolution skin imaging.

SignificanceLine-field confocal optical coherence tomography (LC-OCT) is a recently introduced high-resolution imaging modality based on a combination of low-coherence optical interferometry and reflectance confocal optical microscopy with line illumination and line detection. Capable of producing three-dimensional (3D) images of the skin with cellular resolution, in vivo, LC-OCT has been mainly applied in dermatology and dermo-cosmetology. The LC-OCT devices capable of acquiring 3D images reported so far are based on a Linnik interferometer using two identical microscope objectives. In this configuration, LC-OCT cannot be designed to be a very compact and light device, and the image acquisition speed is limited.AimThe objective of this work was to develop a more compact and lighter LC-OCT device that is capable of acquiring images faster without significant degradation of the resolution and with optimized detection sensitivity.ApproachWe developed an LC-OCT device based on a Mirau interferometer using a single objective. Dynamic adjustment of the camera frequency during the depth scan is implemented, using a faster camera and a more powerful light source. The reflectivity of the beam-splitter in the Mirau interferometer was optimized to maximize the detection sensitivity. A galvanometer scanner was incorporated into the device for scanning the illumination line laterally. A stack of adjacent B-scans, constituting a 3D image, can thus be acquired.ResultsThe device is able to acquire and display B-scans at 17 fps. 3D images with a quasi-isotropic resolution of (1.3, 1.9, and in the , and directions, respectively) over a field of () can be obtained. 3D imaging of human skin at cellular resolution, in vivo, is reported.ConclusionsThe acquisition rate of the B-scans, at 17 fps, is unprecedented in LC-OCT. Compared with the conventional LC-OCT devices based on a Linnik interferometer, the reported Mirau-based LC-OCT device can acquire B-scans times faster. With potential advantages in terms of compactness and weight, a Mirau-based device could easily be integrated into a smaller and lighter handheld probe for use by dermatologists in their daily medical practice.

Optical clearing and testing of lung tissue using inhalation aerosols: prospects for monitoring the action of viral infections.

Optical clearing of the lung tissue aims to make it more transparent to light by minimizing light scattering, thus allowing reconstruction of the three-dimensional structure of the tissue with a much better resolution. This is of great importance for monitoring of viral infection impact on the alveolar structure of the tissue and oxygen transport. Optical clearing agents (OCAs) can provide not only lesser light scattering of tissue components but also may influence the molecular transport function of the alveolar membrane. Air-filled lungs present significant challenges for optical imaging including optical coherence tomography (OCT), confocal and two-photon microscopy, and Raman spectroscopy, because of the large refractive-index mismatch between alveoli walls and the enclosed air-filled region. During OCT imaging, the light is strongly backscattered at each air–tissue interface, such that image reconstruction is typically limited to a single alveolus. At the same time, the filling of these cavities with an OCA, to which water (physiological solution) can also be attributed since its refractive index is much higher than that of air will lead to much better tissue optical transmittance. This review presents general principles and advances in the field of tissue optical clearing (TOC) technology, OCA delivery mechanisms in lung tissue, studies of the impact of microbial and viral infections on tissue response, and antimicrobial and antiviral photodynamic therapies using methylene blue (MB) and indocyanine green (ICG) dyes as photosensitizers.

(Digital Presentation) Monitoring and Controlling Tautomerization in Phthalocyanines, Porphyrines and Porphycenes By Optical Single-Molecule Imaging and Spectroscopy

Tautomerization is an intramolecular chemical reaction defined as structural interconversion of a molecule between two isomers separated by a low energy barrier. Tautomerization in free base phthalocyanines, porphyrins or porphycenes has fascinated and attracted chemists and physicists alike over the last decades for its fundamental importance in various chemical and biological systems and many applications in technology [1,2]. Particularly interesting is the reaction rate which can range over orders of magnitude depending on the temperature and the local environment. In solution, this reaction in porphycenes occurs usually in several picoseconds or even faster, as determined via anisotropy studies by ultrafast transient absorption spectroscopy [3] and in porphyrins at cryogenic temperatures it can last for hours or days as determined form the live time of narrow spectral holes photochemically burned in the inhomogeneously broadened absorption band with a narrow band laser [4]. However, a spectacular and unexpected observation has been made by optical single molecule imaging and spectroscopy [5]. Examining a large number of single molecules embedded at low concentration in various polymer matrices at room temperature has revealed unquestionably that the rate in these molecules can vary dramatically over time such that tautomerization can be frozen for seconds and longer under ambient conditions[6]. The interconversion of the inner protons of phthalocyanine changes the orientation of the transition dipole moment by 90o degrees with respect to the molecular structure. Hence, if these molecules are embedded with a fixed orientation in a transparent solid polymer film at high dilution and tautomerization is frozen, the orientation of their transition dipole moments can be determined by polarization spectroscopy.Here we report on our recent experimental and theoretical studies of monitoring tautomerization by fluorescence imaging of single molecules of phthalocyanines, porphyrins, or porphycenes excited in the tightly focused azimuthally and radially polarized laser beam with a sample scanning confocal optical microscope equipped with single photon counting electronics and a fluorescence spectrometer. This technique has been used to determine the transition dipole moment orientation of single molecules, the polarizability of plasmonic nanoparticles or the dimensionality of single quantum dots. Different diffraction limited fluorescence intensity patterns are observed for molecules that undergo tautomerization and for those that do not. The latter corresponds to a molecule with a fixed transition dipole moment direction, whereas the tautomerizing molecule can be treated as the superposition of two emitters with different transition dipole moment orientations.Previous studies have shown that tautomerization in porphyrins or phthalocyanines can occur via ground state tunneling and is frozen at low temperatures, particularly at cryogenic temperatures. The structural heterogeneity in a polymer matrix leads to a distribution of asymmetrically distorted ground state double well potential and hence can lead to long residence times in the deeper energy minimum. However, even at helium temperatures tautomerization can be induced by electronic excitation to the first excited state, making photochemical spectral hole-burning possible. Recently we could demonstrate in a single-molecule study that the tautomerization rate of phthalocyanine tetrasulfonate embedded in a thin PVA-film at room temperature could be controlled in a tunable λ/2 Fabry Perot resonator by weak coupling between the electronically excited state and the vacuum electromagnetic field of a resonant cavity mode.

Fiber-based hand-held RCM-OCT probe for noninvasive assessment of skin lesions and therapy guidance.

Noninvasive assessment of skin lesions, especially of basal cell carcinoma (BCC), has benefited more recently from the use of optical imaging techniques such as optical coherence tomography (OCT) and reflectance confocal microscopy (RCM). While RCM provides submicron scale resolution and thus enables identification of skin morphological changes of the skin, with the downside of limited penetration depth, OCT imaging of the same lesion brings the benefit of better resolving its depth of invasion. OCT and RCM can be used either individually or combined within the same instrument for the noninvasive diagnosis of nonmelanoma skin cancers (NMSCs). Their combined use has shown to provide certain benefits such as better characterization of the lesion's margins, both in depth and laterally, as well as improved sensitivity and specificity, as previously demonstrated by our team. In this paper we report a new "fiber-based" implementation of the second-generation RCM-OCT hand-held probe. The fiber-based implementation of both imaging modalities enabled the construction of a smaller footprint/lower weight hand-held probe. Its preliminary evaluation on the skin of healthy volunteers is reported here, demonstrating improved capabilities for resolving sub-cellular structures and image skin morphology with micron-scale resolution to a higher depth than in the previous implementation, while also enabling the construction of angiography maps showing vascular remodeling.

Sputter ion source cathode pit reconstruction by stylus profilometer, optical techniques and X-ray micro computed tomography

In Caesium sputter ion sources of negative ions, SNICS, an accurate reconstruction of pit profiles is important to assess the efficiency of cathode material utilization to increase the output of negative ions. Highly accurate pit profile measurements in sputter cathodes are difficult to perform for geometries where the depth is large compared to the diameter. In this paper, optical confocal microscopy, stylus profilometry and X-ray micro-computer tomography are used successfully to reliably reconstruct such high aspect ratio cathode pit geometries. Simulations of Cs+ beam trajectories and calculated cross-sectional current density distributions are consistent with the observed pit profiles. Experimental results demonstrate the practicability of the proposed measurement techniques for SNICS cathodes and other structures with complex surface topographies.

Real-time and space visualization of excitations of the ν=1/3 fractional quantum Hall edge

The authors observe propagations of collective excitations existing at in the fractional quantum Hall regime and demonstrate optical stroboscopic confocal microscopy by synchronizing an electric voltage pulse with an optical pulse.

Hydraulic Resistance and Macromolecular Structure of Aerobic and Anaerobic Mixed-Culture Extracellular Polymeric Substances Gel Layers: Opportunities and Challenges

Soluble Extracellular Polymeric Substances (sEPS) are a mixture of microbial soluble polymers produced during aerobic or anaerobic treatment of wastewater. Gel layers mainly consisting of sEPS are usually present in the fouling layers of membrane bioreactors (MBRs) and in the dynamic membranes (DMs) of dynamic membrane bioreactors (DMBRs), and their properties have not been thoroughly investigated over the years. In this study, sEPS fractions recovered from aerobic and anaerobic reactors were analyzed and tested to build-up EPS gel layers on a 0.2 µm pore size polycarbonate carrier. Dead-end filtration experiments showed that anaerobic sEPS layers, which have a low polysaccharide:protein (PS:PN) ratio, had a lower hydraulic resistance than the aerobic sEPS gel layers, which show a high PS:PN ratio. Optical Coherence Tomography (OCT) and Confocal Laser Scanning Microscopy (CLSM) analyses highlighted that both layers had similar thicknesses and 3D structural organizations. Fluorescent staining of organics and biovolume analysis revealed that for the anaerobic sEPS (low PS:PN), the abundance of proteins appears to destabilize the polysaccharide network increasing the water permeability through the layer. Additionally, the polysaccharides present in the anaerobic sEPS were mainly of the α-linked type, contributing to a more open crosslinked network within the layer, resulting in the low filtration resistance measured. The filtration characteristics observed in this study for the sEPS layers from anaerobic mixed cultures are of interest for possible future application of those layers as dynamic membranes within anaerobic reactors.

Micro-EDM Drilling/Milling as a Potential Technique for Fabrication of Bespoke Artificial Defects on Bearing Raceways.

The fabrication of bespoke artificial defects on bearing raceways helps in mimicking incipient faults during real application or for directly validating the diagnostic technology depending on their shapes and sizes. This is particularly useful when run-to-failure experiments are time-consuming and even difficult in some cases. However, there has been limited systematic research on the design and fabrication of artificial defects on bearing raceways, particularly for the purpose of accelerated testing. In this work, micro-EDM is put forward as a potential technique for the fabrication of artificial defects using drilling/milling mode. A methodology is developed, not only to achieve the full control of the dimension and distribution of defects on a bearing element, but also to qualitatively and quantitatively perform the efficient characterization of the defect surface. A linear regression model with the inclusion of two-way interactions based on an analysis of variance (ANOVA) is presented to optimally select the process parameters. The verification experiments show that this mathematical model obtains a good fit for approximately 80% of the observed data. Through a combination of optical microscopy and confocal microscopy, the morphology and topography of the artificial defects was measured and compared. To conclude, micro-EDM evidences its great potential in terms of machining efficiency, e.g., with an MRR of 0.060 , TWR of 0.032 and dimensional controllability, e.g., the standard deviation of pitting diameter and depth being 0.5 µm and 0.8 µm, respectively, to achieve a desirable feature shape for bearing defects.

Long-Term Clinical Outcomes of Small-Incision Femtosecond Laser-Assisted Intracorneal Concave Lenticule Implantation in Patients with Keratoconus.

Purpose The purpose of this study was to evaluate the long-term prognosis of small-incision femtosecond laser-assisted intracorneal concave lenticule implantation (SFII) in correction of human keratoconus. Methods This was a prospective study for 11 patients who received SFII after being diagnosed as progressive keratoconus based on the Amsler–Krumeich classification system. Clinical assessment was performed for all the patients prior to and postsurgically at different time points for 5 years. These included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), biomechanically corrected intraocular pressure (bIOP), corneal topography, anterior segment optical coherence tomography (AS-OCT), confocal microscopy, and biomechanical assessment with Corvis ST. Results Comparison of preoperative and 60-month postoperative UDVA and CDVA (P60months=0.081 and 0.001, respectively), all eyes showed an improvement in CDVA. Corneal topography showed no significant changes in corneal anterior K1, K2, posterior K1, K2, posterior elevation, or corneal densitometry compared with preoperative levels (P > 0.05). Corvis ST showed that central corneal thickness (CCT) and stiffness at applanation 1 (SP-A1) were significantly greater 1 week postsurgically when compared to the baseline (P < 0.05) and remained stable thereafter. The lenticule under the AS-OCT remained transparent throughout the entire postsurgical period. Under confocal microscopy, corneal edema and an increase in cell activation and reflectivity were observed at the lenticule-stromal interface within 1 week postoperatively. These reactions gradually subsided with time within 6 months. Conclusion SFII is an effective procedure to prevent the progression of keratoconus due to its minimal invasiveness and capability of maintaining a steady biometry of the cornea.

Interferon-gamma inhibits influenza A virus cellular attachment by reducing sialic acid cluster size

SummaryThe mucosal antiviral role of type I and III interferon in influenza virus infection is well established. However, much less is known about the antiviral mechanism of type II interferon (interferon-gamma). Here, we revealed an antiviral mechanism of interferon-gamma by inhibiting influenza A virus (IAV) attachment. By direct stochastic optical reconstruction microscopy, confocal microscopy, and flow cytometry, we have shown that interferon-gamma reduced the size of α-2,3 and α-2,6-linked sialic acid clusters, without changing the sialic acid or epidermal growth factor receptor expression levels, or the sialic acid density within cluster on the cell surface of A549 cells. Reversing the effect of interferon-gamma on sialic acid clustering by jasplakinolide reverted the cluster size, improved IAV attachment and replication. Our findings showed the importance of sialic acid clustering in IAV attachment and infection. We also demonstrated the interference of sialic acid clustering as an anti-IAV mechanism of IFN-gamma for IAV infection.