Investigation of corrosion damage of wrought aluminium alloys at full-scale accelerated tests. Part 2. Pitting corrosion

2019 ◽  
pp. 175-187
Author(s):  
M. Kurs ◽  
A. Goncharov
Keyword(s):  
Pitting Corrosion ◽  
Laser Scanning ◽  
Corrosion Damage ◽  
Full Scale ◽  
Laser Scanning Microscopy ◽  
Accelerated Tests ◽  
Corrosion Failure ◽  
Accuracy Of Measurements

The paper presents the results of a study of pitting corrosion of aluminum alloys of seven doping systems after testing by the full-scale accelerated method. The advantages of the method of laser scanning microscopy in the analysis of pitting corrosion are shown, which makes it possible to improve significantly the accuracy of measurements in comparison with the metallographic method. Peculiarities of the kinetics of pitting growth under long-term, accelerated tests were studied, the role of pitting corrosion in the part of characterizing the alloy’s susceptibility to local corrosion failure was shown. 

High Bond Durability of Universal Adhesives on Glass Ceramics Facilitated by Silane Pretreatment

2018 ◽  
Vol 43 (6) ◽  
pp. 602-612 ◽  
Author(s):  
C Yao ◽  
H Yang ◽  
J Yu ◽  
L Zhang ◽  
Y Zhu ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Glass Ceramics ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Single Bond ◽  
Thermal Cycles ◽  
Universal Adhesive ◽  
Universal Adhesives ◽  
Resin Bonding

SUMMARY Objective: This study aimed to investigate the long-term effectiveness of ceramic–resin bonding with universal adhesives in non–silane-pretreated and silane-pretreated modes after 10,000 cycles of thermal aging. Methods and Materials: All Bond Universal, Adhese Universal, Clearfil Universal Bond, and Single Bond Universal were selected. Etched lithium disilicate glass ceramics were prepared, randomly assigned to groups, and pretreated with or without ceramic primer containing silane coupling agent prior to the application of universal adhesive (ie, silane-pretreated or non–silane-pretreated mode). The shear bond strength (SBS), microleakage, and field-emission scanning electron microscopy images of the ceramic–resin interfaces were examined after 24 hours of water storage or 10,000 thermal cycles. Light microscopy and confocal laser scanning microscopy (CLSM) were performed to analyze marginal sealing ability. Results: SBS and microleakage percentage were significantly affected by bonding procedure (non–silane-pretreated or silane-pretreated mode) and aging (24 hours or 10,000 thermal cycles). After the universal adhesives in the non–silane-pretreated mode were aged, SBS significantly decreased and microleakage percentage increased. By contrast, the SBS of Adhese Universal, Clearfil Universal Bond, and Single Bond Universal decreased, and the microleakage percentage of all of the adhesives increased in the silane-pretreated mode. However, after aging, the SBS of the silane-pretreated groups were higher and their microleakage percentages lower than those of the non–pretreated groups. In the non–silane-pretreated mode, adhesive failure was dominant and gaps between composite resin and the adhesive layer were significant when observed with CLSM. Conclusions: The simplified procedure reduced the ceramic–resin bonding effectiveness of universal adhesives after aging, and additional silane pretreatment helped improve the long-term durability.

scholarly journals Potential role of nuclear translocation of glyceraldehyde-3-phosphate dehydrogenase in apoptosis and oxidative stress

2001 ◽  
Vol 114 (9) ◽  
pp. 1643-1653 ◽  
Author(s):  
Z. Dastoor ◽  
J.L. Dreyer
Keyword(s):  
Oxidative Stress ◽  
Laser Scanning ◽  
Fluorescent Protein ◽  
Nuclear Translocation ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Apoptotic Cells ◽  
Transfected Cells ◽  
And Oxidative Stress

Recent studies indicating a role of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in apoptosis or oxidative stress has been reported. Using confocal laser-scanning microscopy, we have investigated the cellular distribution of GAPDH in central nervous system (CNS)-derived cells (neuroblastoma mNB41A3), in non-CNS derived cells (R6 fibroblast) and in an apoptosis-resistant Bcl2 overexpressing cell line (R6-Bcl2). Induction of apoptosis by staurosporine or MG132 and oxidative stress by H(2)O(2) or FeCN enhanced the nuclear translocation of endogenous GAPDH in all cell types, as detected by immunocytochemistry. In apoptotic cells, GAPDH expression is three times higher than in non-apoptotic cells. Consistent with a role for GAPDH in apoptosis, overexpression of a GAPDH-green fluorescent protein (GAPDH-GFP) hybrid increased nuclear import of GAPDH-GFP into transfected cells and the number of apoptotic cells, and made them more sensitive to agents that induce apoptosis. Bcl2 overexpression prevents nuclear translocation of GAPDH and apoptosis in untransfected cells, but not in transfected cells that overexpress GAPDH-GFP. Our observations indicate that nuclear translocation of GAPDH may play a role in apoptosis and oxidative stress, probably related to the activity of GAPDH as a DNA repair enzyme or as a nuclear carrier for pro-apoptotic molecules.

scholarly journals Cell Adherence and Drug Delivery from Particle Based Mesoporous Silica Films

2019 ◽  
Author(s):  
Emma Björk ◽  
Bernhard Baumann ◽  
Florian Hausladen ◽  
Rainer Wittig ◽  
mika lindén
Keyword(s):  
Drug Delivery ◽  
Laser Scanning ◽  
Single Cells ◽  
Silicon Wafers ◽  
Laser Scanning Microscopy ◽  
Drug Uptake ◽  
C2c12 Cells ◽  
Confocal Laser ◽  
Particle Sizes

Spatially and temporally controlled drug delivery is important for implant and tissue engineering applications, as the efficacy and bioavailability of the drug can be enhanced, and can also allow for drugging stem cells at different stages of development. Long-term drug delivery over weeks to months is however difficult to achieve, and coating of 3D surfaces or creating patterned surfaces is a challenge using coating techniques like spin- and dip-coating. In this study, mesoporous films consisting of SBA-15 particles grown onto silicon wafers using wet processing were evaluated as a scaffold for drug delivery. Films with various particle sizes (100 – 900 nm) and hence thicknesses were grown onto OTS-functionalized silicon wafers using a direct growth method. Precise patterning of the areas for film growth could be obtained by local removal of the OTS functionalization through laser ablation. The films were incubated with the model drug DiO, and murine myoblast cells (C2C12 cells) were seeded onto films with different particle sizes. Confocal laser scanning microscopy (CLSM) was used to study the cell growth, and a vinculin-mediated adherence of C2C12 cells on all films was verified. The successful loading of DiO into the films was confirmed by UV-vis and CLSM. It was observed that the drugs did not desorb from the particles during 24 hours in cell culture. During adherent growth on the films for 4 h, small amounts of DiO and separate particles were observed inside single cells. After 24 h, a larger number of particles and a strong DiO signal were recorded in the cells, indicating a particle mediated drug uptake. A substantial amount of DiO loaded particles were however attached on the substrate after 24 making the films attractive as a long-term reservoir for drugs on e.g. medical implants.<br>

scholarly journals Pericapillary Edema Assessment by Means of the Nailfold Capillaroscopy and Laser Scanning Microscopy

Diagnostics ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1107
Author(s):  
Boris P. Yakimov ◽  
Yury I. Gurfinkel ◽  
Denis A. Davydov ◽  
Anastasia S. Allenova ◽  
Gleb S. Budylin ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Venous Occlusion ◽  
Laser Scanning Microscopy ◽  
Scanning Microscopy ◽  
Confocal Laser ◽  
Human Organism ◽  
Infusion Therapy ◽  
Image Sharpness ◽  
Short Term

Edema, i.e., fluid accumulation in the interstitial space, accompanies numerous pathological states of the human organism, including heart failure (HF), inflammatory response, and lymphedema. Nevertheless, techniques for quantitative assessment of the edema’s severity and dynamics are absent in clinical practice, and the analysis is mainly limited to physical examination. This fact stimulates the development of novel methods for fast and reliable diagnostics of fluid retention in tissues. In this work, we focused on the possibilities of two microscopic techniques, nailfold video capillaroscopy (NVC) and confocal laser scanning microscopy (CLSM), in the assessment of the short-term and long-term cutaneous edema. We showed that for the patients with HF, morphological parameters obtained by NVC—namely, the apical diameter of capillaries and the size of the perivascular zone—indicate long-term edema. On the other hand, for healthy volunteers, the application of two models of short-term edema, venous occlusion, and histamine treatment of the skin, did not reveal notable changes in the capillary parameters. However, a significant reduction of the NVC image sharpness was observed in this case, which was suggested to be due to water accumulation in the epidermis. To verify these findings, we made use of CLSM, which provides the skin structure with cellular resolution. It was observed that for the histamine-treated skin, the areas of the dermal papillae become hyporefractive, leading to the loss of contrast and the lower visibility of capillaries. Similar effect was observed for patients undergoing infusion therapy. Collectively, our results reveal the parameters can be used for pericapillary edema assessment using the NVC and CLSM, and paves the way for their application in a clinical set-up.

Detection and enumeration of microbial cells within highly porous calcareous reef sands

2006 ◽  
Vol 57 (4) ◽  
pp. 415 ◽  
Author(s):  
Christian Wild ◽  
Christian Laforsch ◽  
Markus Huettel
Keyword(s):  
Laser Scanning ◽  
Complex Surface ◽  
Porous Matrix ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Size Spectrum ◽  
Order Of Magnitude ◽  
Grain Surface ◽  
Highly Porous

In order to assess and to compare the abundances of prokaryotes in coral sands from three different areas in the Indo-Pacific, a technique was developed and evaluated for enumeration of prokaryotes living on and within calcareous grains. Propidium iodide labelling of prokaryotes and consecutive confocal laser scanning microscopy showed microbial colonisation within pores and small fissures of the coral sands. This embedded microbial colonisation required at least four extractions with weak acetic acid to dissolve the grain surface layer in order to detach 97% of the prokaryotic cells. Microbial enumeration based on this technique revealed that the abundance of prokaryotes in the carbonate sands were not significantly different among the three sites, but were about one order of magnitude higher than reported for silicate sands of a similar grain size spectrum. A possible reason for this high abundance of prokaryotes is the complex surface structure of the biogenic calcareous grains, their correspondingly highly porous matrix and the associated ability of prokaryotes to penetrate into carbonate grains. Our results highlight the role of calcareous reef sands as a substratum with a large specific surface area for prokaryotic colonisation and emphasise the contribution of calcium carbonate reef sands for element cycles in subtropical and tropical ecosystems.

scholarly journals Antibody response to the 45 kDa Candida albicans antigen in an animal model and potential role of the antigen in adherence

2008 ◽  
Vol 57 (12) ◽  
pp. 1466-1472 ◽  
Author(s):  
Helena Bujdáková ◽  
Ema Paulovičová ◽  
Silvia Borecká-Melkusová ◽  
Juraj Gašperík ◽  
Soňa Kucharíková ◽  
...  
Keyword(s):  
Animal Model ◽  
Candida Albicans ◽  
Biofilm Formation ◽  
Laser Scanning ◽  
Vaccine Development ◽  
Laser Scanning Microscopy ◽  
Model Systems ◽  
Confocal Laser

The Candida antigen CR3-RP (complement receptor 3-related protein) is supposed to be a ‘mimicry’ protein because of its ability to bind antibody directed against the α subunit of the mammalian CR3 (CD11b/CD18). This study aimed to (i) investigate the specific humoral isotypic response to immunization with CR3-RP in vivo in a rabbit animal model, and (ii) determine the role of CR3-RP in the adherence of Candida albicans in vitro using the model systems of buccal epithelial cells (BECs) and biofilm formation. The synthetic C. albicans peptide DINGGGATLPQ corresponding to 11 amino-acids of the CR3-RP sequence DINGGGATLPQALXQITGVIT, determined by N-terminal sequencing, was used for immunization of rabbits to obtain polyclonal anti-CR3-PR serum and for subsequent characterization of the humoral isotypic response of rabbits. A significant increase of IgG, IgA and IgM anti-CR3-RP specific antibodies was observed after the third (P<0.01) and the fourth (P<0.001) immunization doses. The elevation of IgA levels suggested peptide immunomodulation of the IgA1 subclass, presumably in coincidence with Candida epithelial adherence. Blocking CR3-RP with polyclonal anti-CR3-RP serum reduced the ability of Candida to adhere to BECs, in comparison with the control, by up to 35 % (P<0.001), and reduced biofilm formation by 28 % (P<0.001), including changes in biofilm thickness and integrity detected by confocal laser scanning microscopy. These properties of CR3-RP suggest that it has potential for future vaccine development.

Deletion of bem46 retards spore germination and may be related to the polar growth of Aspergillus fumigatus

2019 ◽  
Vol 58 (5) ◽  
pp. 690-697
Author(s):  
Yan Ma ◽  
Ying Ji ◽  
Jing Yang ◽  
Wen Li ◽  
Jiajuan Li ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Laser Scanning ◽  
Fluorescent Protein ◽  
Morphological Changes ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Polarized Growth ◽  
Bud Emergence ◽  
Green Fluorescent

Abstract Bud emergence 46 (BEM46), a member of the α/β hydrolase superfamily, has been reported to be essential for polarized growth in Neurospora crassa. However, the role of BEM46 in aspergillus fumigatus (A. fumigatus) remains unclear. In this study, we constructed an A. fumigatus strain expressing BEM46 fused with enhanced green fluorescent protein, and a Δbem46 mutant, to explore the localization and the role of growth of BEM46 in A. fumigatus, respectively. Confocal laser scanning microscopy revealed that BEM46 was dominantly expressed in the sites where hyphae germinated from conidia in A. fumigatus. When compared with the control strain, the Δbem46 mutant exhibited insignificant morphological changes but delayed germination. No significant changes were found regarding the radial growth of both strains in response to various antifungal agents. These results suggest that BEM46 plays an essential role in timely germination in A. fumigatus. From the observation of fluorescence localization, we infer that that BEM46 might be involved in polarized growth in A. fumigatus.

Neuron model system: Correlative confocal laser scanned microscopy and membrane physiology

1990 ◽  
Vol 48 (3) ◽  
pp. 170-171
Author(s):  
Donald H. Szarowski ◽  
Michael Fejtl ◽  
Paul McCauley ◽  
David O. Carpenter ◽  
James N. Turner
Keyword(s):  
Laser Scanning ◽  
Model System ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Patch Clamping ◽  
Surface Geometry ◽  
Receptor Stimulation ◽  
Membrane Physiology ◽  
Conventional Light Microscopy

Confocal laser scanning microscopy (CLSM) has been used to correlate morphology and membrane physiology in cultured neurons, providing a model system for studying physiologic and pathologic conditions. Ion channels are studied by patch-clamp methods as a function of receptor stimulation and toxic excitatory amino acids, including those implicated in Alzheimer’s dementia. Glial cells are often closely associated with the neurons, and are difficult to detect in living cultures due to the relative sizes of glia and neurons (5-20 μm versus 125 μm), compounded with the fact that they are thick phase objects. Groups of glia can also be confused with neurons. Thus it is difficult to select appropriate cells and/or cell regions for patch-clamping. We are correlating physiology and conventional light microscopy with CLSM to determine the role of glia, and neuron surface geometry on the ability to establish Gigaohm membrane-micropipette seals. Morphology of the system as observed by CLSM is presented here.

Time-resolved study of biofilm architecture and transport processes using experimental and simulation techniques: the role of EPS

2001 ◽  
Vol 43 (6) ◽  
pp. 143-151 ◽  
Author(s):  
M. Kuehn ◽  
M. Mehl ◽  
M. Hausner ◽  
H.-J. Bungartz ◽  
S. Wuertz
Keyword(s):  
Solute Transport ◽  
Confocal Laser Scanning Microscopy ◽  
Laser Scanning ◽  
Extracellular Polymeric Substances ◽  
Transport Processes ◽  
Laser Scanning Microscopy ◽  
Confocal Laser Scanning ◽  
Scanning Microscopy ◽  
Confocal Laser

Cellular material and extracellular polymeric substances are the basic structural elements in biofilm systems. The structure and role of EPS for biofilm development and metabolic processes have not been precisely determined and, therefore, have not yet been included as a necessary element in modelling and simulation studies. This is due to the difficulty of experimentally detecting the extracellular polymeric substances in situ and differentiating them from cellular material on the one hand, and to the subsequent uncertainty about appropriate models - e.g. rigid hindrances, porous microstructure or visco-elastic structure - on the other hand. In this work, we report on the use of confocal laser scanning microscopy to monitor the development of a monoculture biofilm of Sphingomonas sp. grown in a flow cell. The bacterial strain was genetically labelled resulting in strong constitutive expression of the green fluorescent protein. The development of extracellular polymeric substances was followed bybinding of the lectin concavalin A to cell exopolysaccharides. The growth of the resulting strain was digitally recorded by automated confocal laser scanning microscopy. In addition, local velocity profiles of fluorescent carboxylate-modified microspheres were observed on pathlines throughout the biofilm. The CLSM image stacks were used as direct input for the explicit modelling and three-dimensional numerical simulation of flow fields and solute transport processes based on the conservation laws of continuum mechanics. At present, a strongly simplifying EPS-model is applied for numerical simulations. The EPSs are preliminarily assumed to behave like a rigid and dense hindrance with diffusive-reactive solute transport.

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