scholarly journals Quantitative Imaging and In Situ Concentration Measurements of Quantum Dot Nanomaterials in Variably Saturated Porous Media

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Burcu Uyuşur ◽  
Preston T. Snee ◽  
Chunyan Li ◽  
Christophe J. G. Darnault
Keyword(s):  
Porous Media ◽  
Quantum Dot ◽  
Light Transmission ◽  
Water Saturation ◽  
Uv Light ◽  
Light Exposure ◽  
Fluorescence Method ◽  
Fluorescent Light ◽  
Subsurface Environment

Knowledge of the fate and transport of nanoparticles in the subsurface environment is limited, as techniques to monitor and visualize the transport and distribution of nanoparticles in porous media and measure their in situ concentrations are lacking. To address these issues, we have developed a light transmission and fluorescence method to visualize and measure in situ concentrations of quantum dot (QD) nanoparticles in variably saturated environments. Calibration cells filled with sand as porous medium and various known water saturation levels and QD concentrations were prepared. By measuring the intensity of the light transmitted through porous media exposed to fluorescent light and by measuring the hue of the light emitted by the QDs under UV light exposure, we obtained simultaneously in situ measurements of water saturation and QD nanoparticle concentrations with high spatial and temporal resolutions. Water saturation was directly proportional to the light intensity. A linear relationship was observed between hue-intensity ratio values and QD concentrations for constant water saturation levels. The advantages and limitations of the light transmission and fluorescence method as well as its implications for visualizing and measuring in situ concentrations of QDs nanoparticles in the subsurface environment are discussed.

DIFFUSED ČERENKOV LIGHT MEASUREMENTS FOR THE EUSO PROJECT

2005 ◽  
Vol 20 (29) ◽  
pp. 6906-6908
Author(s):  
P. VALLANIA ◽  
A. CAPPA ◽  
L. FAVA ◽  
P. GALEOTTI ◽  
O. SAAVEDRA ◽  
...  
Keyword(s):  
Light Transmission ◽  
Uv Light ◽  
Fluorescent Light ◽  
Fluorescent Signal ◽  
Extensive Air Shower ◽  
Air Shower ◽  
The Earth ◽  
Shower Energy ◽  
Cerenkov Light ◽  
Transmission And Reflection

The aim of the EUSO (Extreme Universe Space Observatory) experiment is to measure from space the fluorescent light produced by the interaction of Extreme Energy Cosmic Rays (EECRs) with the Earth atmosphere. Besides the fluorescent signal, a huge amount of Čerenkov photons is emitted in a narrow cone hitting the Earth surface, where it is partially diffused. The detection of this diffused signal, in a delayed coincidence with the fluorescent signal, allows the absolute positioning of the EECR track, while the knowledge of the diffusing properties of the surface gives an independent indication of the shower energy. Measuring simultaneously on ground the electromagnetic component, the direct Čerenkov light, and the diffused Čerenkov light over different surfaces, we aim to characterize the emitted signal as a function of the energy and the arrival direction of the Extensive Air Shower (EAS), and to evaluate its possible detection from space. This is implemented by the ULTRA (Uv Light Transmission and Reflection in the Atmosphere) experiment composed by a small EAS array and a UltraViolet (UV) telescope. The experimental setups used in the first runs at sea level and at 1970 m a.s.l. are described and the first preliminary results are presented.

Strength Properties of Flexible Geogrids Under Indoor and Outdoor Ultraviolet Exposure

2003 ◽  
Vol 1849 (1) ◽  
pp. 221-230 ◽  
Author(s):  
Chiwan Wayne Hsieh ◽  
Chien Kuei Lin
Keyword(s):  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Carbon Black ◽  
Uv Light ◽  
Light Exposure ◽  
Outdoor Exposure ◽  
Uv Exposure ◽  
Fluorescent Light ◽  
Exposure Condition ◽  
Coating Materials

The outdoor ultraviolet (UV) light exposure program according to ASTM D5970 and the indoor UV fluorescent lamp device according to ASTM G154 were used to evaluate the UV degradation in test polyester geogrids. Eighteen months’ worth of data were obtained from the outdoor program. UV-A-340 lamps and exposure condition No. 7 were used for the indoor program. The outdoor exposure program was conducted at Pingtung, in southern Taiwan. The annual sunlight exposure energy was 4,263.50 MJ/m2. The accumulated annual UV-A and UV-B energies were 256.56 and 0.83 MJ/m2, respectively. The tensile strength of the test geogrids decreased as the outdoor exposure increased, but the decrease in the rate of tensile strength also lessened as UV exposure increased. Carbon black and antioxidants contained in the coating materials have a significant influence on the rate of degradation for the test geogrids; 2% carbon black and 1% antioxidant by weight are recommended. The proportions of average retained ultimate tensile strength for 1 month, 12 months, and 18 months of outdoor exposure were 88%, 71%, and 66%, respectively. The tensile strength half-life cycle due to UV exposure was greater than 18 months. Similar behavior was also observed for the elongation at break. However, no clear trend was found for strength at 5% strain due to UV exposure. The reduction factors due to 18 months of outdoor exposure varied from 1.27 to 1.99. The average reduction factor was about 1.60. The reduction in ultimate tensile strength under 180 h of UV exposure in the indoor UV exposure test program was very significant. However, the rate of lost tensile strength for the second and third 180-h UV exposure was very small. The average retained tensile strengths for the geogrids under 180-h and 540-h exposures were 81% and 77%, respectively. The effect of 540-h fluorescent light exposure on the tensile strength of polyester geogrids coated with polyvinyl chloride was equivalent to 151 days of outdoor exposure at Pingtung.

scholarly journals Stability and Photoisomerization of Stilbenes Isolated from the Bark of Norway Spruce Roots

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1036
Author(s):  
Harri Latva-Mäenpää ◽  
Riziwanguli Wufu ◽  
Daniel Mulat ◽  
Tytti Sarjala ◽  
Pekka Saranpää ◽  
...  
Keyword(s):  
Norway Spruce ◽  
Uv Light ◽  
Light Exposure ◽  
Fluorescent Light ◽  
Spectroscopic Techniques ◽  
Functional Ingredients ◽  
The Stability ◽  
Antibacterial And Antifungal ◽  
New Compounds ◽  
And Storage

Stilbenes or stilbenoids, major polyphenolic compounds of the bark of Norway spruce (Picea abies L. Karst), have potential future applications as drugs, preservatives and other functional ingredients due to their antioxidative, antibacterial and antifungal properties. Stilbenes are photosensitive and UV and fluorescent light induce trans to cis isomerisation via intramolecular cyclization. So far, the characterizations of possible new compounds derived from trans-stilbenes under UV light exposure have been mainly tentative based only on UV or MS spectra without utilizing more detailed structural spectroscopy techniques such as NMR. The objective of this work was to study the stability of biologically interesting and readily available stilbenes such as astringin and isorhapontin and their aglucones piceatannol and isorhapontigenin, which have not been studied previously. The effects of fluorescent and UV light and storage on the stability of trans stilbenes were assessed and the identification and characterisation of new compounds formed during our experiments were carried out by chromatographic (HPLC, GC) and spectroscopic techniques (UV, MS, NMR). The stilbenes undergo a trans to cis isomerisation under extended UV irradiation by intramolecular cyclisation (by the formation of a new C-C bond and the loss of two hydrogens) to phenanthrene structures. The characterised compounds are novel and not described previously.

Effects of Light Stabilizer on the Mechanical Properties of Poly-p-phenylenebenzobisoxazole Fibers under Sunlight Irradiation

2012 ◽  
Vol 550-553 ◽  
pp. 3335-3338
Author(s):  
Jun Hong Jin ◽  
Sheng Lin Yang ◽  
Guang Li ◽  
Jian Ming Jiang
Keyword(s):  
Mechanical Properties ◽  
In Situ Polymerization ◽  
Uv Light ◽  
Light Exposure ◽  
Sunlight Irradiation ◽  
Light Stabilizer ◽  
Spinning Process ◽  
Pbo Fiber ◽  
Strength Retention

In this work, light aging resistant PBO fiber containing light stabilizer (OB-1) was prepared via in-situ polymerization and dry-jet wet-spinning process. The mechanical properties of the fibers under sunlight radiation were investigated by tensile testing. PBO fiber is sensitive to both UV light and sunlight, and undergoes severe degradation under light exposure. After exposed to sunlight and sunlight sealed from humidity for 318h the strength retention is only 25.39% and 33.08%, respectively. The light stability of PBO can be enhanced with only a small amount (0.05-0.2%) of addition of OB-1. Under the same conditions the strength retention of 0.2%OB-1/PBO fiber is 55.52% and 64.84%, which is 119% and 96% higher than that of PBO fiber.

scholarly journals Antimicrobial Activity of TiO2Nanoparticle-Coated Film for Potential Food Packaging Applications

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Siti Hajar Othman ◽  
Nurul Raudhah Abd Salam ◽  
Norhazlizam Zainal ◽  
Roseliza Kadir Basha ◽  
Rosnita A. Talib
Keyword(s):  
Antimicrobial Activity ◽  
Food Packaging ◽  
Uv Light ◽  
Light Exposure ◽  
Antimicrobial Property ◽  
Fluorescent Light ◽  
Packaging Film ◽  
E Coli ◽  
Coated Film ◽  
Potential Food

Recent uses of titanium dioxide (TiO2) have involved various applications which include the food industry. This study aims to develop TiO2nanoparticle-coated film for potential food packaging applications due to the photocatalytic antimicrobial property of TiO2. The TiO2nanoparticles with varying concentrations (0–0.11 g/ 100 mL organic solvent) were coated on food packaging film, particularly low density polyethylene (LDPE) film. The antimicrobial activity of the films was investigated by their capability to inactivateEscherichia coli(E. coli) in an actual food packaging application test under various conditions, including types of light (fluorescent and ultraviolet (UV)) and the length of time the film was exposed to light (one–three days). The antimicrobial activity of the TiO2nanoparticle-coated films exposed under both types of lighting was found to increase with an increase in the TiO2nanoparticle concentration and the light exposure time. It was also found that the antimicrobial activity of the films exposed under UV light was higher than that under fluorescent light. The developed film has the potential to be used as a food packaging film that can extend the shelf life, maintain the quality, and assure the safety of food.

scholarly journals Preferential Flow Systems Amended with Biogeochemical Components: Imaging of a Two-Dimensional Study

2017 ◽  
Author(s):  
Ashley R. Pales ◽  
Biting Li ◽  
Heather M. Clifford ◽  
Shyla Kupis ◽  
Nimisha Edayilam ◽  
...  
Keyword(s):  
Porous Media ◽  
Preferential Flow ◽  
Light Transmission ◽  
Water Saturation ◽  
Silica Sand ◽  
Two Dimensional ◽  
Unstable Flow ◽  
Transmission Method ◽  
Soil Component ◽  
Plant Exudates

Abstract. The vadose zone is a highly interactive heterogeneous system through which water enters into the subsurface system by infiltration. This paper details the effects of simulated plant exudate and soil component solutions upon unstable flow patterns in a porous media (ASTM silica sand; US Silica, Ottawa, IL, USA) through the use of two-dimensional (2D) tank light transmission method (LTM). The contact angle and surface tension of two simulated plant exudate solutions (i.e. oxalate, and citrate) and two soil component solutions (i.e. tannic acid, and Suwannee River Natural Organic Matter) were analyzed to determine the liquid-gas and liquid-solid interface characteristics of each. To determine if the unstable flow formations were dependent on the type and concentration of the simulated plant exudates and soil components, the analysis of the effects of the simulated plant exudate and soil component solutions were compared to a control rainwater solution. The differences in the fingering flow were quantified with the finger geometries, the velocity of finger propagation, the vertical and horizontal water saturation profiles, and the water saturation at the fingertips. Significant differences in the interface processes indicated a decrease between the control and the plant exudate and soil component solutions tested; specifically, the control at 64.5 θ and 75.75 Nm/m, to the low concentration of citrate at 52.6 θ and 70.8 Nm/m. The changes in finger geometries and velocity of propagation between the control solution and the simulated plant exudate and soil component solutions further demonstrate that the plant exudates increased the wettability and mobility of the solutions during the infiltration process in unsaturated porous media.

A Photoactivatable α5β1-Specific Integrin Ligand

2018 ◽  
Author(s):  
Roshna Vakkeel ◽  
Aleeza Farrukh ◽  
Aranzazu del Campo
Keyword(s):  
Cellular Response ◽  
Light Exposure ◽  
Matrix Composition ◽  
Cellular Behavior ◽  
Dynamic Variations ◽  
In Situ Activation ◽  
Controlled Exposure ◽  
Cellular Behaviour ◽  
Integrin Ligand

In order to study how dynamic changes of α5β1 integrin engagement affect cellular behaviour, photoactivatable derivatives of α5β1 specific ligands are presented in this article. The presence of the photoremovable protecting group (PRPG) introduced at a relevant position for integrin recognition, temporally inhibits ligand bioactivity. Light exposure at cell-compatible dose efficiently cleaves the PRPG and restores functionality. Selective cell response (attachment, spreading, migration) to the activated ligand on the surface is achieved upon controlled exposure. Spatial and temporal control of the cellular response is demonstrated, including the possibility to in situ activation. Photoactivatable integrin-selective ligands in model microenvironments will allow the study of cellular behavior in response to changes in the activation of individual integrins as consequence of dynamic variations of matrix composition.

Probing the Dynamic Self-Assembly Behaviour of Photoswitchable Wormlike Micelles in Real Time

2018 ◽  
Author(s):  
Elaine A. Kelly ◽  
Judith E. Houston ◽  
Rachel Evans
Keyword(s):  
Real Time ◽  
Absorption Spectroscopy ◽  
Self Assembly ◽  
Uv Light ◽  
Wormlike Micelles ◽  
Tetraethylene Glycol ◽  
Light Illumination ◽  
First Time ◽  
Dependent Processes

Understanding the dynamic self-assembly behaviour of azobenzene photosurfactants (AzoPS) is crucial to advance their use in controlled release applications such as<i></i>drug delivery and micellar catalysis. Currently, their behaviour in the equilibrium <i>cis-</i>and <i>trans</i>-photostationary states is more widely understood than during the photoisomerisation process itself. Here, we investigate the time-dependent self-assembly of the different photoisomers of a model neutral AzoPS, <a>tetraethylene glycol mono(4′,4-octyloxy,octyl-azobenzene) </a>(C<sub>8</sub>AzoOC<sub>8</sub>E<sub>4</sub>) using small-angle neutron scattering (SANS). We show that the incorporation of <i>in-situ</i>UV-Vis absorption spectroscopy with SANS allows the scattering profile, and hence micelle shape, to be correlated with the extent of photoisomerisation in real-time. It was observed that C<sub>8</sub>AzoOC<sub>8</sub>E<sub>4</sub>could switch between wormlike micelles (<i>trans</i>native state) and fractal aggregates (under UV light), with changes in the self-assembled structure arising concurrently with changes in the absorption spectrum. Wormlike micelles could be recovered within 60 seconds of blue light illumination. To the best of our knowledge, this is the first time the degree of AzoPS photoisomerisation has been tracked <i>in</i><i>-situ</i>through combined UV-Vis absorption spectroscopy-SANS measurements. This technique could be widely used to gain mechanistic and kinetic insights into light-dependent processes that are reliant on self-assembly.

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