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.

UV Irradiation of Shell Eggs: Effect on Populations of Aerobes, Molds, and Inoculated Salmonella typhimurium

1997 ◽  
Vol 60 (6) ◽  
pp. 639-643 ◽  
Author(s):  
FUENG-LIN KUO ◽  
JOHN B. CAREY ◽  
STEVEN C. RICKE
Keyword(s):  
Salmonella Typhimurium ◽  
Uv Radiation ◽  
Uv Light ◽  
The Other ◽  
Uv Exposure ◽  
Microbial Populations ◽  
Aerobic Bacteria ◽  
Fluorescent Light ◽  
Uv Treatment ◽  
Shell Eggs

The effects were investigated of 254-nm UV radiation on populations of Salmonella typhimurium, aerobes, and molds on the shells of eggs. In the first experiment, the CFU of attached S. typhimurium cells on unwashed clean shell eggs were determined after 0, 1, 3, 5, and 7 min of UV treatment (620 μW/cm2) on both ends of the egg. All UV treatments significantly reduced S. typhimurium CFU (P < .01). UVtreatment (620 μW/cm2) in 1-min alternating light and dark cycles for 5 min (three light and two dark) was compared to 0, 3, and 5 min of UV treatment. No significant differences in microbial populations were observed among light and dark cycles and the other UV treatments. In a subsequent experiment, the same UV treatments were utilized to evaluate photoreactivation. After UV exposure, eggs were exposed to 1 h of fluorescent light or I h of darkness or cultured immediately. S. typhimurium CFU were significantly (P < .01) reduced by the UV treatments. However, no significant differences between microbial populations exposed to UV treatment and UV radiation plus photoreactivation were detected. For studies of aerobic bacteria and molds, different UV treatment times (0, 15, and 30 min) at the intensity of 620 μW/cm2 and different intensities (620, 1350, and 1720 μW/cm2) for 15 min were evaluated. Mold CFU per egg were either 0 or 1 for all UV treatments and a 99% reduction of CFU of aerobic bacteria per egg were observed for all UV treatments. It appears from these studies that UV light can significantly reduce populations of S. typhimurium, aerobes, and molds on shell eggs.

Impact of Process Parameters on the Tensile Properties of DLP Additively Manufactured ELAST-BLK 10 UV-Curable Elastomer

2021 ◽  
Author(s):  
Asma Ul Hosna Meem ◽  
Kyle Rudolph ◽  
Allyson Cox ◽  
Austin Andwan ◽  
Timothy Osborn ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Elastic Modulus ◽  
Ultimate Tensile Strength ◽  
Tensile Properties ◽  
Process Parameters ◽  
Uv Light ◽  
Uv Curable ◽  
Build Orientation ◽  
Static Tensile ◽  
The Impact

Abstract Digital light processing (DLP) is an emerging vatphotopolymerization-based 3D-printing technology where full layers of photosensitive resin are irradiated and cured with projected ultraviolet (UV) light to create a three-dimensional part layer-by-layer. Recent breakthroughs in polymer chemistry have led to a growing number of UV-curable elastomeric photoresins developed exclusively for vat photopolymerization additive manufacturing (AM). Coupled with the practical manufacturing advantages of DLP AM (e.g., industry-leading print speeds and sub-micron-level print resolution), these novel elastomeric photoresins are compelling candidates for emerging applications requiring extreme flexibility, stretchability, conformability, and mechanically-tunable stiffness (e.g., soft robotic actuators and stretchable electronics). To advance the role of DLP AM in these novel and promising technological spaces, a fundamental understanding of the impact of DLP manufacturing process parameters on mechanical properties is requisite. This paper highlights our recent efforts to explore the process-property relationship for ELAST-BLK 10, a new commercially-available UV-curable elastomer for DLP AM. A full factorial design of experiments is used to investigate the effect of build orientation and layer thickness on the quasi-static tensile properties (i.e., small-strain elastic modulus, ultimate tensile strength, and elongation at fracture) of ELAST-BLK 10. Statistical results, based on a general linear model via ANOVA methods, indicate that specimens with a flat build orientation exhibit the highest elastic modulus, ultimate tensile strength, and elongation at fracture, likely due to a larger surface area that enhances crosslink density during the curing process. Several popular hyperelastic constitutive models (e.g., Mooney-Rivlin, Yeoh, and Gent) are calibrated to our quasi-static tensile data to facilitate component-level predictive analyses (e.g., finite-element modeling) of soft robotic actuators and other emerging soft-matter applications.

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.

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.

Experimental Study on the Effect of Adding Carbon Black Powder on Tensile Strength of LDPE Films under Artificial Weathering Condition

2013 ◽  
Vol 330 ◽  
pp. 32-36
Author(s):  
S.A.M. Rezavand ◽  
S. Falah Kordi ◽  
T. Azdast
Keyword(s):  
Tensile Strength ◽  
Carbon Black ◽  
Tensile Stress ◽  
Uv Light ◽  
Extrusion Process ◽  
Strength Test ◽  
Artificial Weathering ◽  
Tensile Strength Test ◽  
Carbon Black Powder ◽  
Plastic Parts

The properties of plastic parts that used for outdoor applications are changed under weathering conditions. Weathering involves considering the effects of solar radiation, temperature, humidity, pollutants. By adding some additives such as carbon black, TiO2, Hals and Tinuvin, the weathering effect could be decreased. In this study, LDPE films by adding different percentages (0.1, 0.5 and 1%) of carbon black (C.B.) with 0.2 mm thickness were produced by extrusion process. Samples were cut according to ASTM D882 and to accelerate the tests, samples located in accelerated artificial weathering device up to 1400 hour. The device was set at 40°C and humidity of 50%. Required samples for tensile strength test bring out of device at selected period and tensile strength was done by 350 mm/min strain rate. The results show that samples containing carbon black have tensile stress and elongationmore than the clear films. Carbon black absorbs UV light and heat that causing to delay in broken links and destroying the molecular. The optimum percent for tensile stress was 0.5 and for elongation was 1% C.B.

scholarly journals Inhibition of Polyimide Photodegradation by Incorporation of Titanate Nanotubes into a Composite

2020 ◽  
Author(s):  
Christian Harito ◽  
Dmitry V Bavykin ◽  
Brian Yuliarto ◽  
Hermawan K Dipojono ◽  
Frank C Walsh
Keyword(s):  
Methylene Blue ◽  
Raman Spectroscopy ◽  
Brittle Material ◽  
Uv Light ◽  
Light Exposure ◽  
Polymer Chains ◽  
Plasticity Index ◽  
Uv Exposure ◽  
Spectroscopy Optical ◽  
Positively Charged

The effect of UV light exposure on the properties of hexafluoroisopropylidene-diphthalic anhydride–oxydianiline (6FDA–ODA) polyimide (PI) and polyimide–titanate nanotube (TiNT/PI) composites has been studied using Raman spectroscopy, optical microscopy, nanoidentation and TEM. The degree of polymer photodegradation was estimated by measuring the change in affinity to a positively charged dye (methylene blue, MB). The mechanism of photoassisted transformations in polyimides usually involves scission of polymer chains accompanied by appearance of active radicals, which undergo further rapid transformations to more stable phenol, amine, and carboxylic functional groups. The accumulation of these groups can increase the degree of adsorption of charged dyes in the photodegraded polymer. It was found that neat PI showed a significantly increased capacity to adsorb MB after irradiation with UV, reaching a plateau after 1 h. In contrast, TiNT/PI composite demonstrated a much slower rise in concentration of adsorbed MB even after 4 h of UV exposure. Raman spectra indicated cleavage of C=O and C–F bonds in PI while only the C–F bond was damaged in TiNT/PI. Shorter cracks (≈ 40 µm long) appeared in TiNT/PI composites whereas macro cracks (> 100 µm) were visible in neat PI after 3 h of UV exposure. Brittleness was studied by comparing plasticity index which varied from 0 to 1 (0 corresponding to the most brittle material and 1 the most ductile one). Plasticity index reduced by 51% and 2% for PI and TiNT/PI, respectively after 3 h UV irradiation, indicating that TiNT can protect underlying PI from further damage. The hardness of neat PI decreased whereas, for TiNT/PI, it increased under UV, suggesting crosslinking of broken polymer chains with nanotubes.

scholarly journals The Influence of Sunlight Exposure and Sun Protecting Behaviours on Allergic Outcomes in Early Childhood

2021 ◽  
Vol 18 (10) ◽  
pp. 5429
Author(s):  
Kristina Rueter ◽  
Anderson P. Jones ◽  
Aris Siafarikas ◽  
Paola Chivers ◽  
Susan L. Prescott ◽  
...  
Keyword(s):  
Vitamin D ◽  
Early Childhood ◽  
Allergic Disease ◽  
Environmental Changes ◽  
Uv Light ◽  
Light Exposure ◽  
Outdoor Exposure ◽  
Vitamin D Supplementation ◽  
Sunlight Exposure ◽  
Dramatic Rise

The dramatic rise in allergic disease has occurred in tandem with recent environmental changes and increasing indoor lifestyle culture. While multifactorial, one consistent allergy risk factor has been reduced sunlight exposure. However, vitamin D supplementation studies have been disappointing in preventing allergy, raising possible independent effects of ultraviolet (UV) light exposure. The aim of this study was to examine whether UV light exposure influences the development of allergic disease in early childhood. Direct sunlight exposure (290–380 nm) in early infancy was measured via UV dosimeters. Outdoor exposure, sun protective behaviours, and allergy outcomes were assessed over the first 2.5 years of life with clinical assessment appointments at 3, 6, 12 and 30 months of age. Children with eczema had less (p = 0.038) direct UV light exposure between 0-3 months of age (median (IQR) 747 (473–1439) J/m2) than children without eczema (median (IQR) 1204 (1717–1843) J/m2); and less outdoor exposure time (7 min/day) between 11 a.m. and 3 p.m. compared to children without eczema (20 min/day, p = 0.011). These associations were seen independent of vitamin D status, and after adjusting for other potential confounders. Whilst we could not find any associations between direct UV light exposure and other allergic disease outcomes, exposure to UV light appears to be beneficial in reducing the risk of eczema development in early childhood. Further research is required to determine optimal levels of UV light exposure while balancing the potential risks.

scholarly journals Association among pterygium, cataracts, and cumulative ocular ultraviolet exposure: A cross-sectional study in Han people in China and Taiwan

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0253093
Author(s):  
Natsuko Hatsusaka ◽  
Naoki Yamamoto ◽  
Hisanori Miyashita ◽  
Eri Shibuya ◽  
Norihiro Mita ◽  
...  
Keyword(s):  
Uv Light ◽  
Light Exposure ◽  
Cross Sectional Study ◽  
Classification Systems ◽  
Uv Exposure ◽  
Cross Sectional ◽  
High Prevalence ◽  
Surface Disorder ◽  
Progress Rate ◽  
Ocular Surface Disorder

Purpose Pterygium is an ocular surface disorder mainly caused by ultraviolet (UV) light exposure. This study explored the relationships between six cataract types with pterygium and UV exposure. Methods We have previously studied cataracts in residents of three regions in China and Taiwan with different UV intensities. From that study, we identified 1,547 subjects with information on the presence or absence of pterygium. Pterygium severity was graded by corneal progress rate. Cataracts were graded by classification systems as three main types (cortical, nuclear, posterior subcapsular) and three subtypes (retrodots, waterclefts, fiber folds) with high prevalence in middle-aged and elderly people. We calculated the cumulative ocular UV exposure (COUV) based on subject data and National Aeronautics and Space Administration data on UV intensities and used logistic regression to calculate odds ratios for the associations of COUV, cataract, and pterygium. Results We found an overall pterygium prevalence of 23.3%, with significant variation among the three regions. Four cataract types (cortical, nuclear, posterior subcapsular, and retrodots) were significantly associated with the presence of pterygium. Conclusions There was a significant association between COUV and pterygium, indicating that COUV is associated with the risk of pterygium development and that pterygium is useful as an index of UV exposure. Furthermore, the type of cataract in eyes with pterygium may indicate the level of UV exposure.

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.

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