Seawater activated TiO2 photocatalyst for degradation of organic compounds

The world's oceans are polluted by a continuous inflow of plastic. Plastic fragments finally into microplastic, which can be taken up, for example by plankton, and subsequently by the entire ocean food web. An approach to reduce plastic pollution constitutes the accelerated microplastic degradation in marine environments. TiO₂ (anatase) is commonly used as an oxidative photocatalyst and well known to catalyze the degradation of organic compounds upon UV irradiation.In this study, a selective activation of TiO₂ (anatase) particles encapsulated by Ca- or Sr-polyphosphate is presented. The TiO₂ polyphosphate core-shell particles are envisaged as additives in plastic products. The highly concentrated cations from seawater, viz. Na⁺ and Mg²⁺, displace the Ca²⁺ or Sr²⁺ cations from the polyphosphate shell. As a result, the polyphosphate coating dissolves and thus the photocatalytically active TiO₂ core is released. The stability of the TiO₂ polyphosphate particles in potable water and the seawater activated disintegration of methylene blue, methyl methacrylate, terephtalic acid, and poly(vinyl alcohol) was shown. It has been demonstrated, that the sweetwater stable polyphosphate coating degrades in the presence of seawater, which could be monitored by the activation of the TiO₂ (anatase) photocatalyst.     

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 ∼1.5μm (1.3, 1.9, and 1.1μm in the x,y, and z directions, respectively) over a field of 940μm×600μm×350μm (x×y×z) 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 ∼2 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.     

Histomorphometry of the human optic nerve

This study was undertaken to measure number, diameter and distribution of nerve fibers in normal human optic nerves. Twenty-two optic nerves of 19 subjects aged between 20 and 75 years were histomorphometrically examined using semithin sections obtained in a distance of 2 to 5 mm behind the globe. The mean nerve fiber count was 1,159,000 +/- 196,000 with a minimum of 816,000 and a maximum of 1,502,000. The significant (P = 0.025) loss per year of age was approximately 5426 nerve fibers. For eight subjects the nerve fiber count was independent of the size and form of the optic disc. The mean minimal nerve fiber diameter averaged 1.00 +/- 0.06 micron (range: 0.1-8.3 microns). It was significantly smaller in the temporal and inner region of the optic nerve than in the nasal and outer area, respectively. Correspondingly, nerve fiber count per area was significantly higher in the temporal and inner parts of the optic nerve than in the nasal and outer parts, respectively. Statistically different size classes could not be detected. The optic nerve cross-section area excluding the leptomeninges (mean 8.09 +/- 1.38 mm2) increased significantly with the nerve fiber count. The marked interindividual variability of the nerve fiber count may influence interindividual comparisons of psychophysical examinations. It can indicate an interindividually different anatomic "reserve capacity" in the course of optic nerve diseases. The age-dependent nerve fiber loss, among other factors, may partially explain the decreased visual performance of older subjects. It should be considered in progression and "pseudoprogression" of optic nerve diseases like glaucoma. The intraindividually high variability of the nerve fiber size may correspond to different retinal ganglion cell populations.     

Predicting Sensitivity to Adverse Lifestyle Risk Factors for Cardiometabolic Morbidity and Mortality

People appear to vary in their susceptibility to lifestyle risk factors for cardiometabolic disease; determining a priori who is most sensitive may help optimize the timing, design, and delivery of preventative interventions. We aimed to ascertain a person’s degree of resilience or sensitivity to adverse lifestyle exposures and determine whether these classifications help predict cardiometabolic disease later in life; we pooled data from two population-based Swedish prospective cohort studies (n = 53,507), and we contrasted an individual’s cardiometabolic biomarker profile with the profile predicted for them given their lifestyle exposure characteristics using a quantile random forest approach. People who were classed as ‘sensitive’ to hypertension- and dyslipidemia-related lifestyle exposures were at higher risk of developing cardiovascular disease (CVD, hazards ratio 1.6 (95% CI: 1.3, 1.91)), compared with the general population. No differences were observed for type 2 diabetes (T2D) risk. Here, we report a novel approach to identify individuals who are especially sensitive to adverse lifestyle exposures and who are at higher risk of subsequent cardiovascular events. Early preventive interventions may be needed in this subgroup.     

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