Impact of the LED-based light source working regime on the degradation of polymethyl methacrylate

2019 ◽  
Vol 52 (1) ◽  
pp. 94-105 ◽  
Author(s):  
A Sikora ◽  
K Tomczuk
Keyword(s):  
Polymethyl Methacrylate ◽  
Pulse Width Modulation ◽  
Morphological Changes ◽  
Detection Sensitivity ◽  
Force Microscopy ◽  
Dc Power ◽  
Atomic Force ◽  
High Roughness ◽  
The Impact ◽  
Non Destructive

The popularity of LED-based luminaires has increased enormously in recent years. Every such luminaire consists of several elements including a polymer-based transparent housing, yet some of the ageing aspects of specific luminaire materials have not been investigated. In this paper, we present research aimed at determining the impact of LED lamp powering mode on polymer material deterioration. In the experiment, three LED lamp operating systems based on two different pulse width modulation units and one DC power source were used to induce deterioration in a polymethyl methacrylate sample. Two types of LEDs, white and ultraviolet, were considered as the most significant in terms of the impact on the material. Observations of the surface's morphological changes were performed to enable non-destructive investigation of the degradation of the exposed samples. In order to obtain high roughness detection sensitivity, atomic force microscopy was used. We observed various ageing ratios of the material, despite the fact that total average optical energy for specific wavelengths was equal for all samples. The importance of these findings for designing modern luminaires is discussed.

scholarly journals Deswelling Induced Morphological Changes in Dual pH and Temperature Responsive Ultra-Low Crosslinked Poly (N-Isopropyl Acrylamide)-Co-Acrylic Acid Microgels

2018 ◽  
Author(s):  
Molla Islam ◽  
Maddie Tumbarello ◽  
Andrew Lyon
Keyword(s):  
Light Scattering ◽  
Acrylic Acid ◽  
Morphological Changes ◽  
Scattering Data ◽  
Ionization State ◽  
Force Microscopy ◽  
Temperature Responsive ◽  
Atomic Force ◽  
Isopropyl Acrylamide ◽  
The Impact

<div>We demonstrated the deswelling induced morphological change in dual pH and Temperature responsive ultra-low crosslinked Poly (N-isopropyl acrylamide)-co-acrylic acid microgels. The responsivity with pH and temperature were studied by light scattering and atomic force microscopy. Light scattering data suggest that at pH 4.5 the microgels undergo multiple transitions associated with collapse of pNIPAm-rich segments and repulsion between the AAc-rich segments. The evolution of punctate structures around the periphery or throughout the whole microgels at pH 4.5 and 6.5 respectively was revealed by AFM, further illustrating the heterogeneous deswelling present in the ionized copolymer microgels.</div><div>The impact of this study and understanding how ionization state of copolymer dictates the overall structural properties of microgels will widen our understanding for their applications in biotechnology</div><div><b><br></b></div>

Modification of InN Properties by Interactions with Hydrogen and Nitrogen

2005 ◽  
Vol 892 ◽  
Author(s):  
Maria Losurdo ◽  
Maria Michela Giangregorio ◽  
Giovanni Bruno ◽  
Tong-Ho Kim ◽  
Pae Wu ◽  
...  
Keyword(s):  
Atomic Hydrogen ◽  
Molecular Beam ◽  
Morphological Changes ◽  
Epitaxial Films ◽  
Intensity Increase ◽  
Force Microscopy ◽  
Atomic Force ◽  
Peak Energy ◽  
Hall Effect Measurements ◽  
The Impact

AbstractThe interaction of InN epitaxial films grown by r.f. plasma assisted molecular beam epitaxy with atomic hydrogen and nitrogen, produced by remote r.f. H2 and N2 plasmas, is investigated. InN strongly reacts with both atomic hydrogen and nitrogen yielding depletion of nitrogen and concurrent formation of In clusters. The impact of hydrogen treatments on the optical properties of InN is assessed using photoluminescence (PL). It is found that hydrogen suppresses the intense PL band peaked at approximately 0.7eV for the as-grown InN epitaxial layers, and results in the appearance of a new PL band whose peak energy and intensity increase with H-dose. The effect of exposure to atomic hydrogen and nitrogen on electrical properties of InN is investigated using Hall effect measurements. Atomic force microscopy is also used for studying the morphological changes of InN upon interaction with atomic hydrogen and nitrogen.

scholarly journals The Role of Modification of the Structure of Water and Water-Containing Systems in Changing Their Biological, Therapeutic, and Other Properties Overview

Water ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2441
Author(s):  
Galina Sidorenko ◽  
Mitja Brilly ◽  
Boris Laptev ◽  
Nikolay Gorlenko ◽  
Leonid Antoshkin ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Mineral Water ◽  
Structural Changes ◽  
Water Clusters ◽  
Force Microscopy ◽  
Structure Of Water ◽  
Atomic Force ◽  
The Impact ◽  
Non Destructive

Based on published research on modifying the structure of water and water-containing systems, we assess external influence methods: temperature, magnetic field, light radiation, and their combination. We evaluate changes in the electrophysical, photo- and pH-metric biological, therapeutic, and other properties of water systems using non-destructive electrophysical research methods, i.e., thermometry, pH, laser interference, dynamic light scattering, microelectrophoresis, conductivity, surface tension, dielectric constant, polarimetric measurements, atomic force microscopy, and UV and EPR spectroscopy. The effects of temperature or magnetic field lead to a change in the content and size of water clusters, and physicochemical, biological, therapeutic, and other changes in the properties of water and water-containing systems. The combined effect of a magnetic field and curative mud and the impact of magnetised mineral water have a more pronounced therapeutic effect than only mineral water or curative mud. The data presented indirectly indicate structural changes in water and water-containing systems. We conclude that the primary mechanism of action of a magnetic field, light, or a combination of these factors on water and water-containing systems, including mineral water and therapeutic mud, is a change in the structure of water.

scholarly journals Deswelling Induced Morphological Changes in Dual pH and Temperature Responsive Ultra-Low Crosslinked Poly (N-Isopropyl Acrylamide)-Co-Acrylic Acid Microgels

2018 ◽  
Author(s):  
Molla Islam ◽  
Maddie Tumbarello ◽  
Andrew Lyon
Keyword(s):  
Light Scattering ◽  
Acrylic Acid ◽  
Morphological Changes ◽  
Scattering Data ◽  
Ionization State ◽  
Force Microscopy ◽  
Temperature Responsive ◽  
Atomic Force ◽  
Isopropyl Acrylamide ◽  
The Impact

<div>We demonstrated the deswelling induced morphological change in dual pH and Temperature responsive ultra-low crosslinked Poly (N-isopropyl acrylamide)-co-acrylic acid microgels. The responsivity with pH and temperature were studied by light scattering and atomic force microscopy. Light scattering data suggest that at pH 4.5 the microgels undergo multiple transitions associated with collapse of pNIPAm-rich segments and repulsion between the AAc-rich segments. The evolution of punctate structures around the periphery or throughout the whole microgels at pH 4.5 and 6.5 respectively was revealed by AFM, further illustrating the heterogeneous deswelling present in the ionized copolymer microgels.</div><div>The impact of this study and understanding how ionization state of copolymer dictates the overall structural properties of microgels will widen our understanding for their applications in biotechnology</div><div><b><br></b></div>

scholarly journals Extracellular Vesicles Analysis in the COVID-19 Era: Insights on Serum Inactivation Protocols towards Downstream Isolation and Analysis

Cells ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 544
Author(s):  
Roberto Frigerio ◽  
Angelo Musicò ◽  
Marco Brucale ◽  
Andrea Ridolfi ◽  
Silvia Galbiati ◽  
...  
Keyword(s):  
Extracellular Vesicles ◽  
Analytical Techniques ◽  
Heat Inactivation ◽  
Force Microscopy ◽  
Atomic Force ◽  
Droplet Pcr ◽  
Detergent Treatment ◽  
Routine Procedures ◽  
The Impact ◽  
Mirna Content

Since the outbreak of the COVID-19 crisis, the handling of biological samples from confirmed or suspected SARS-CoV-2-positive individuals demanded the use of inactivation protocols to ensure laboratory operators’ safety. While not standardized, these practices can be roughly divided into two categories, namely heat inactivation and solvent-detergent treatments. These routine procedures should also apply to samples intended for Extracellular Vesicles (EVs) analysis. Assessing the impact of virus-inactivating pre-treatments is therefore of pivotal importance, given the well-known variability introduced by different pre-analytical steps on downstream EVs isolation and analysis. Arguably, shared guidelines on inactivation protocols tailored to best address EVs-specific requirements will be needed among the analytical community, yet deep investigations in this direction have not yet been reported. We here provide insights into SARS-CoV-2 inactivation practices to be adopted prior to serum EVs analysis by comparing solvent/detergent treatment vs. heat inactivation. Our analysis entails the evaluation of EVs recovery and purity along with biochemical, biophysical and biomolecular profiling by means of a set of complementary analytical techniques: Nanoparticle Tracking Analysis, Western Blotting, Atomic Force Microscopy, miRNA content (digital droplet PCR) and tetraspanin assessment by microarrays. Our data suggest an increase in ultracentrifugation (UC) recovery following heat treatment; however, it is accompanied by a marked enrichment in EVs-associated contaminants. On the other hand, solvent/detergent treatment is promising for small EVs (<150 nm range), yet a depletion of larger vesicular entities was detected. This work represents a first step towards the identification of optimal serum inactivation protocols targeted to EVs analysis.

Structuring of Silicon Wafer Surfaces on the Sub-100 nm Scale by Hydrogen Plasma Treatments

2003 ◽  
Vol 788 ◽  
Author(s):  
R. Job ◽  
Y. Ma ◽  
A. G. Ulyashin
Keyword(s):  
Hydrogen Plasma ◽  
Structural Defects ◽  
Process Conditions ◽  
Force Microscopy ◽  
Czochralski Silicon ◽  
Atomic Force ◽  
Nano Structures ◽  
Plasma Treatments ◽  
The Impact ◽  
Wafer Surfaces

ABSTRACTHydrogen plasma treatments applied on standard Czochralski silicon (Cz Si) wafers cause a structuring of the surface regions on the sub-100 nm scale, i.e. a thin ‘nano-structured’ Si layer is created up to a depth of ∼ 150 nm. The formation of the ‘nano-structures’ and their evolution in dependence on the process conditions was studied. The impact of post-hydrogenation annealing on the morphology of the structural defects was studied up to 1200 °C. The H-plasma treated and annealed samples were analyzed at surface and sub-surface regions by scanning electron microscopy (SEM), atomic force microscopy (AFM), and μ-Raman spectroscopy.

scholarly journals Effects of suspended micro- and nanoscale particles on zooplankton functional diversity of drainage system reservoirs at an open-pit mine

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Anna Maria Goździejewska ◽  
Monika Gwoździk ◽  
Sławomir Kulesza ◽  
Mirosław Bramowicz ◽  
Jacek Koszałka
Keyword(s):  
Functional Diversity ◽  
Drainage System ◽  
Open Pit ◽  
Nanoscale Particles ◽  
X Ray ◽  
Force Microscopy ◽  
Suspension Parameters ◽  
Atomic Force ◽  
Size Of Particles ◽  
The Impact

Abstract Water from mining drainage is turbid because of suspensions. We tested the hypothesis that the chemical composition as well as shape and size of particles in suspensions of natural origin affect the density and functional diversity of zooplankton. The suspensions were analyzed with atomic force microscopy (AFM), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), and optical microscopy. Elements found in the beidellite clays were also identified in the mineral structure of the particles. As the size of the microparticles decreased, the weight proportions of phosphorus, sulfur, and chlorine increased in the suspensions. These conditions facilitated the biomass growth of large and small microphages and raptorials. As the size of the nanoparticles decreased, the shares of silicon, aluminum, iron, and magnesium increased. These conditions inhibited raptorials the most. Ecosystem functionality was the highest with intermediate suspension parameters, which were at the lower range of the microphase and the upper range of the nanophase. The functional traits of zooplankton demonstrate their potential for use as sensitive indicators of disruptions in aquatic ecosystems that are linked with the presence of suspensions, and they facilitate gaining an understanding of the causes and scales of the impact of suspensions.

scholarly journals Touch-induced seedling morphological changes are determined by ethylene-regulated pectin degradation

2020 ◽  
Vol 6 (48) ◽  
pp. eabc9294
Author(s):  
Qingqing Wu ◽  
Yue Li ◽  
Mohan Lyu ◽  
Yiwen Luo ◽  
Hui Shi ◽  
...  
Keyword(s):  
Cell Wall ◽  
Morphological Changes ◽  
Mechanical Forces ◽  
Ethylene Signaling ◽  
Pectin Degradation ◽  
Force Microscopy ◽  
Mechanical Responses ◽  
Atomic Force ◽  
Wall Stiffness ◽  
Molecular Framework

How mechanical forces regulate plant growth is a fascinating and long-standing question. After germination underground, buried seedlings have to dynamically adjust their growth to respond to mechanical stimulation from soil barriers. Here, we designed a lid touch assay and used atomic force microscopy to investigate the mechanical responses of seedlings during soil emergence. Touching seedlings induced increases in cell wall stiffness and decreases in cell elongation, which were correlated with pectin degradation. We revealed that PGX3, which encodes a polygalacturonase, mediates touch-imposed alterations in the pectin matrix and the mechanics of morphogenesis. Furthermore, we found that ethylene signaling is activated by touch, and the transcription factor EIN3 directly associates with PGX3 promoter and is required for touch-repressed PGX3 expression. By uncovering the link between mechanical forces and cell wall remodeling established via the EIN3-PGX3 module, this work represents a key step in understanding the molecular framework of touch-induced morphological changes.

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