Discrete structure of ultrathin dielectric films and their surface optical properties

The boundary problem of linear classical optics about the interaction of electromagnetic radiation with a thin dielectric film has been solved under explicit consideration of its discrete structure. The main attention has been paid to the investigation of the near-zone optical response of dielectrics. The laws of reflection and refraction for discrete structures in the case of a regular atomic distribution are studied and the structure of evanescent harmonics induced by an external plane wave near the surface is investigated in details. It is shown by means of analytical and numerical calculations that due to the existence of the evanescent harmonics the laws of reflection and refraction at the distances from the surface less than two interatomic distances are principally different from the Fresnel laws. From the practical point of view the results of this work might be useful for the near-field optical microscopy of ultrahigh resolution.Comment: 25 pages, 16 figures, LaTeX2.09, to be published in Phys.Rev.

Effect of bioactive glass air-abrasion on the wettability and osteoblast proliferation on sandblasted and acid-etched titanium surfaces

The aim of this study was to evaluate the hydrophilicity, surface free energy, and proliferation and viability of human osteoblast-like MC3T3-E1 cells on sandblasted and acid-etched titanium surfaces after air-abrasion with 45S5 bioactive glass, zinc-containing bioactive glass, or inert glass. Sandblasted and acid-etched titanium discs were subjected to air-abrasion with 45S5 bioactive glass, experimental bioactive glass (Zn4), or inert glass. Water contact angles and surface free energy were evaluated. The surfaces were studied with preosteoblastic MC3T3-E1 cells. Air-abrasion with either type of glass significantly enhanced the hydrophilicity and surface free energy of the sandblasted and acid-etched titanium discs. The MC3T3-E1 cell number was higher for substrates air-abraded with Zn4 bioactive glass and similar to that observed on borosilicate coverslips (controls). Confocal laser scanning microscopy images showed that MC3T3-E1 cells did not spread as extensively on the sandblasted and acid-etched and bioactive glass-abraded surfaces as they did on control surfaces. However, for 45S5- and Zn4-treated samples, the cells spread most at the 24 h time point and changed their morphology to more spindle-like when cultured further. Air-abrasion with bioactive glass and inert glass was shown to have a significant effect on the wettability and surface free energy of the surfaces under investigation. Osteoblast cell proliferation on sandblasted and acid-etched titanium discs was enhanced by air-abrasion with 45S5 bioactive glass and experimental Zn4 bioactive glass compared with air-abrasion with inert glass or no air-abrasion

Antibacterial properties of bioactive glass particle abraded titanium against Streptococcus mutans

The purpose of this study was to evaluate effects of titanium surfaces air-abraded with particles of Bioglass® 45S5 and three-ZnO and SrO doped compositions on the viability, adhesion and biofilm formation of Streptococcus mutans. A statistically significant decrease in the viability of S. mutans was observed for all titanium discs air-particle abraded with the BAGs (p S. mutans adhesion on titanium surfaces treated with different glasses (p = 0.964). Static SBF immersion experiments showed that after 2 and 48 h the BAG doped with 4 mol% ZnO demonstrated the highest Zn2+ ion concentration released into SBF (0.2 mg L−1). 45S5 BAG demonstrated the highest statistically significant increase in the pH throughout the 120 min of static immersion (p S. mutans and they suppressed S. mutans biofilm formation. The antimicrobial activity of 45S5 BAG was attributed to high pH whereas for the Zn-containing BAGs antimicrobial activity was due to steady release of Zn2+ into the interfacial solution.</p

Occurrence of toxigenic microalgal species and phycotoxins accumulation in mesozooplankton in Northern Patagonian gulfs, Argentina

In the Northern Patagonian gulfs of Argentina (Golfo Nuevo and Golfo San José), blooms of toxigenic microalgae and the detection of their associated phycotoxins are recurrent phenomena. The present study evaluated the transfer of phycotoxins from toxigenic microalgae to mesozooplankton in Golfo Nuevo and Golfo San José throughout an annual cycle (December 2014–2015 and January 2015–2016, respectively). In addition, solid‐phase adsorption toxin tracking (SPATT) samplers were deployed for the first time in these gulfs, to estimate the occurrence of phycotoxins in the seawater between the phytoplankton samplings. Domoic acid was present throughout the annual cycle in SPATT samplers, whereas no paralytic shellfish poisoning toxins were detected. Ten toxigenic species were identified: Alexandrium catenella, Dinophysis acuminata, Dinophysis acuta, Dinophysis tripos, Dinophysis caudata, Prorocentrum lima, Pseudo‐nitzschia australis, Pseudo‐nitzschia calliantha, Pseudo‐nitzschia fraudulenta, and Pseudo‐nitzschia pungens. Lipophilic and hydrophilic toxins were detected in phytoplankton and mesozooplankton from both gulfs. Pseudo‐nitzschia spp. were the toxigenic species most frequent in these gulfs. Consequently, domoic acid was the phycotoxin most abundantly detected and transferred to upper trophic levels. Spirolides were detected in phytoplankton and mesozooplankton for the first time in the study area. Likewise, dinophysistoxins were found in mesozooplankton from both gulfs, and this is the first report of the presence of these phycotoxins in zooplankton from the Argentine Sea. The dominance of calanoid copepods indicates that they were the primary vector of phycotoxins in the pelagic trophic web.Fil: D'Agostino, Valeria C.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Krock, Bernd. Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung; AlemaniaFil: Degrati, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Sastre, Viviana. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Santinelli, Norma Herminia. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Krohn, Torben. Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung; AlemaniaFil: Hoffmeyer, Mónica S.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina. Universidad Tecnológica Nacional. Facultad Regional Bahía Blanca; Argentin

Toward Xeno-Free Differentiation of Human Induced Pluripotent Stem Cell-Derived Small Intestinal Epithelial Cells

The small intestinal epithelium has an important role in nutrition, but also in drug absorption and metabolism. There are a few two-dimensional (2D) patient-derived induced pluripotent stem cell (iPSC)-based intestinal models enabling easy evaluation of transcellular transport. It is known that animal-derived components induce variation in the experimental outcomes. Therefore, we aimed to refine the differentiation protocol by using animal-free components. More specifically, we compared maturation of 2D-cultured iPCSs toward small intestinal epithelial cells when cultured either with or without serum, and either on Geltrex or on animal-free, recombinant laminin-based substrata. Differentiation status was characterized by qPCR, immunofluorescence imaging, and functionality assays. Our data suggest that differentiation toward definitive endoderm is more efficient without serum. Both collagen-and recombinant laminin-based coating supported differentiation of definitive endoderm, posterior definitive endoderm, and small intestinal epithelial cells from iPS-cells equally well. Small intestinal epithelial cells differentiated on recombinant laminin exhibited slightly more enterocyte specific cellular functionality than cells differentiated on Geltrex. Our data suggest that functional small intestinal epithelial cells can be generated from iPSCs in serum-free method on xeno-free substrata. This method is easily converted to an entirely xeno-free method.publishedVersionPeer reviewe

Metabolism during anaesthesia and recovery in colic and healthy horses: a microdialysis study

<p>Abstract</p> <p>Background</p> <p>Muscle metabolism in horses has been studied mainly by analysis of substances in blood or plasma and muscle biopsy specimens. By using microdialysis, real-time monitoring of the metabolic events in local tissue with a minimum of trauma is possible. There is limited information about muscle metabolism in the early recovery period after anaesthesia in horses and especially in the colic horse. The aims were to evaluate the microdialysis technique as a complement to plasma analysis and to study the concentration changes in lactate, pyruvate, glucose, glycerol, and urea during anaesthesia and in the recovery period in colic horses undergoing abdominal surgery and in healthy horses not subjected to surgery.</p> <p>Methods</p> <p>Ten healthy university-owned horses given anaesthesia alone and ten client-owned colic horses subjected to emergency abdominal surgery were anaesthetised for a mean (range) of 230 min (193–273) and 208 min (145–300) respectively. Venous blood samples were taken before anaesthesia. Venous blood sampling and microdialysis in the gluteal muscle were performed during anaesthesia and until 24 h after anaesthesia. Temporal changes and differences between groups were analysed with an ANOVA for repeated measures followed by Tukey Post Hoc test or Planned Comparisons.</p> <p>Results</p> <p>Lactate, glucose and urea, in both dialysate and plasma, were higher in the colic horses than in the healthy horses for several hours after recovery to standing. In the colic horses, lactate, glucose, and urea in dialysate, and lactate in plasma increased during the attempts to stand. The lactate-to-pyruvate ratio was initially high in sampled colic horses but decreased over time. In the colic horses, dialysate glycerol concentrations varied considerably whereas in the healthy horses, dialysate glycerol was elevated during anaesthesia but decreased after standing. In both groups, lactate concentration was higher in dialysate than in plasma. The correspondence between dialysate and plasma concentrations of glucose, urea and glycerol varied.</p> <p>Conclusion</p> <p>Microdialysis proved to be suitable in the clinical setting for monitoring of the metabolic events during anaesthesia and recovery. It was possible with this technique to show greater muscle metabolic alterations in the colic horses compared to the healthy horses in response to regaining the standing position.</p

Transitions in bacterial communities along the 2000 km salinity gradient of the Baltic Sea

Salinity is a major factor controlling the distribution of biota in aquatic systems, and most aquatic multicellular organisms are either adapted to life in saltwater or freshwater conditions. Consequently, the saltwater–freshwater mixing zones in coastal or estuarine areas are characterized by limited faunal and floral diversity. Although changes in diversity and decline in species richness in brackish waters is well documented in aquatic ecology, it is unknown to what extent this applies to bacterial communities. Here, we report a first detailed bacterial inventory from vertical profiles of 60 sampling stations distributed along the salinity gradient of the Baltic Sea, one of world's largest brackish water environments, generated using 454 pyrosequencing of partial (400 bp) 16S rRNA genes. Within the salinity gradient, bacterial community composition altered at broad and finer-scale phylogenetic levels. Analogous to faunal communities within brackish conditions, we identified a bacterial brackish water community comprising a diverse combination of freshwater and marine groups, along with populations unique to this environment. As water residence times in the Baltic Sea exceed 3 years, the observed bacterial community cannot be the result of mixing of fresh water and saltwater, but our study represents the first detailed description of an autochthonous brackish microbiome. In contrast to the decline in the diversity of multicellular organisms, reduced bacterial diversity at brackish conditions could not be established. It is possible that the rapid adaptation rate of bacteria has enabled a variety of lineages to fill what for higher organisms remains a challenging and relatively unoccupied ecological niche