scholarly journals An investigation into UV light exposure as an experimental model for artificial aging on tensile strength and force delivery of elastomeric chain

2013 ◽  
Vol 36 (1) ◽  
pp. 47-54 ◽  
Author(s):  
S. W. Wahab ◽  
D. Bister ◽  
M. Sherriff
Keyword(s):  
Tensile Strength ◽  
Experimental Model ◽  
Artificial Aging ◽  
Uv Light ◽  
Light Exposure

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.

Surface Sealant Effect on the Color Stability of a Composite Resin Following Ultraviolet Light Artificial Aging

2019 ◽  
Vol 44 (3) ◽  
pp. 322-330
Author(s):  
A Brooksbank ◽  
BM Owens ◽  
JG Phebus ◽  
BJ Blen ◽  
W Wasson
Keyword(s):  
Artificial Aging ◽  
Composite Resin ◽  
Color Change ◽  
Uv Light ◽  
Light Exposure ◽  
Color Stability ◽  
Acceptable Range ◽  
Color Measurements ◽  
Intergroup Comparison ◽  
Surface Sealant

SUMMARY Objective: To examine how exposure to accelerated artificial aging (AAA) stimuli (ultraviolet [UV] light) affects the color stability of a composite resin following surface sealant (SS) application. Methods and Materials: A total of 30 cylindrical composite resin (Esthet-X) discs were prepared using Teflon-coated rings. The treatment groups, defined by different SS (Seal-N-Sine, PermaSeal, OptiGuard, Biscover LV, and DuraFinish) use, were divided into five groups of six discs each. The discs were subjected to baseline color measurements followed by measurements after surface sealant application (specular included component [SCI] and specular excluded component [SCE]) using a spectrophotometer. Three measurements (SCI and SCE) were performed for a total of 18 readings (test surface) per specimen group. All specimens were then exposed to a UV light source for a total of 382 hours. Color readings of the specimens were again recorded for each group. Quantitative color measurements were executed using Commission Internationale de l'Eclairage L*a*b* calculations. Results: Baseline color measurements of the composite resin discs, following the AAA exposure protocol, revealed no significant differences. A comparison of the composite resin discs before and after SS application (without UV light exposure) showed statistically significant differences using both SCI and SCE measurement criteria. Although significant differences were encountered between the ΔL*, Δa*, Δb*, and ΔE parameters, all specimens (groups) were within the clinically acceptable range (1.0<ΔE≤ 3.3). Again, statistically significant differences were noted (ΔL*, Δa*, Δb*, and ΔE parameters) for all specimen groups receiving SS application, utilizing both SCI and SCE measurements, following exposure to UV light. All groups were within the clinically acceptable range (1.0<ΔE≤ 3.3), except the Durafinish group. The Durafinish SS group experienced significantly greater (p<0.001) overall color change (SCI and SCE) following UV light exposure. An intergroup comparison following UV exposure revealed that the Permaseal, OptiGuard, and Seal-n-Shine SS groups displayed the least amount of color change statistically but not necessarily always perceptibly significant, while the Durafinish group exhibited the greatest color change statistically and perceptibly. Conclusions: The color stability of a composite resin, including the addition of most SSs, was not affected perceptibly by UV light exposure.

scholarly journals Stability and ocular biodistribution of topically administered PLGA nanoparticles

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sean Swetledge ◽  
Renee Carter ◽  
Rhett Stout ◽  
Carlos E. Astete ◽  
Jangwook P. Jung ◽  
...  
Keyword(s):  
Uv Light ◽  
Light Exposure ◽  
Polymeric Nanoparticles ◽  
Plga Nanoparticles ◽  
Eye Disease ◽  
Control Group ◽  
Eye Tissues ◽  
Nanoparticle Morphology ◽  
The Stability

AbstractPolymeric nanoparticles have been investigated as potential delivery systems for therapeutic compounds to address many ailments including eye disease. The stability and spatiotemporal distribution of polymeric nanoparticles in the eye are important regarding the practical applicability and efficacy of the delivery system in treating eye disease. We selected poly(lactic-co-glycolic acid) (PLGA) nanoparticles loaded with lutein, a carotenoid antioxidant associated with eye health, as our model ophthalmic nanodelivery system and evaluated its stability when suspended in various conditions involving temperature and light exposure. We also assessed the ocular biodistribution of the fluorescently labeled nanoparticle vehicle when administered topically. Lutein-loaded nanoparticles were stable in suspension when stored at 4 °C with only 26% lutein release and no significant lutein decay or changes in nanoparticle morphology. When stored at 25 °C and 37 °C, these NPs showed signs of bulk degradation, had significant lutein decay compared to 4 °C, and released over 40% lutein after 5 weeks in suspension. Lutein-loaded nanoparticles were also more resistant to photodegradation compared to free lutein when exposed to ultraviolet (UV) light, decaying approximately 5 times slower. When applied topically in vivo, Cy5-labled nanoparticles showed high uptake in exterior eye tissues including the cornea, episcleral tissue, and sclera. The choroid was the only inner eye tissue that was significantly higher than the control group. Decreased fluorescence in all exterior eye tissues and the choroid at 1 h compared to 30 min indicated rapid elimination of nanoparticles from the eye.

795 A multicenter phase II trial (SWOG S1609, cohort 51) of ipilimumab and nivolumab in metastatic or unresectable angiosarcoma: a substudy of dual anti-CTLA-4 and anti-PD-1 blockade in rare tumors (DART)

2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A843-A843
Author(s):  
Michael Wagner ◽  
Megan Othus ◽  
Sandip Patel ◽  
Christopher Ryan ◽  
Ashish Sangal ◽  
...  
Keyword(s):  
Phase Ii ◽  
Immune Checkpoint ◽  
Uv Light ◽  
Light Exposure ◽  
Case Reports ◽  
Objective Response ◽  
Open Label ◽  
Primary Tumors ◽  
Multicenter Phase ◽  
Grade 3

BackgroundAngiosarcoma is a rare cancer of endothelial cells that can be aggressive and carries a high mortality. A subset of angiosarcomas are characterized by high tumor mutational burden (TMB) and UV light exposure DNA mutational signature. Isolated case reports have suggested clinical efficacy of immune checkpoint blockade in angiosarcoma; no prospective studies of immune checkpoint inhibition in angiosarcoma have been reported. We report efficacy analysis results for patients with advanced or unresectable angiosarcoma treated with ipilimumab and nivolumab as a cohort of an ongoing phase II study for rare cancers (NCT02834013).MethodsThis is a prospective, open-label, multicenter phase II clinical trial of ipilimumab (1mg/kg IV q6weeks) plus nivolumab (240mg IV q2weeks) for patients with metastatic or unresectable angiosarcoma. Primary endpoint is objective response rate as assessed by RECIST v1.1, including measurable cutaneous disease that can be followed by photography. Secondary endpoints include PFS, OS, stable disease at six months, and toxicity. A two-stage design is used with six patients in the first stage and an additional ten patients in the second stage.ResultsAt data cutoff, 16 patients with angiosarcoma were enrolled. Median age was 68 years (25-81 years). Median number of prior lines of therapy was 2 (0-5). 9 patients had cutaneous primary tumors of any cutaneous site, 7 had non-cutaneous primary tumors. ORR for all patients was 25% (4/16, table 1, figure 1). Subgroup analysis revealed that 60% (3/5) of patients with primary cutaneous tumors of the scalp or face had a confirmed objective response. 6-month PFS was 38%. 75% of patients experienced an adverse event (AE), and 25% experienced a grade 3-4 AE. 68.8% experienced an immune related AE (irAE), and 2 (12.5%) developed grade 3 or 4 irAEs. Grade 3-4 irAEs were ALT and AST increase and diarrhea. There were no grade 5 toxicities.ConclusionsThe combination of ipilimumab and nivolumab was well tolerated and had an ORR of 25% in angiosarcoma regardless of primary site, with 3 of 5 patients with cutaneous tumors of the scalp or face responding. Ipilimumab and nivolumab warrant further investigation in angiosarcoma.AcknowledgementsFunding: National Institutes of Health/National Cancer Institute grant awards CA180888, CA180819, CA180868; and in part by Bristol-Myers Squibb CompanyTrial RegistrationNCT02834013Ethics ApprovalThis study was approved by the NCI CIRB.

UV-light-assisted green preparation of Bi/BiOBr/RGO composites with oxygen vacancies toward enhanced photocatalytic removal of organic dye

2020 ◽  
Vol 44 (19) ◽  
pp. 7749-7757 ◽  
Author(s):  
Wen Jia ◽  
Dong Peng ◽  
Zijuan Feng ◽  
Xue Wu ◽  
Yi Liu ◽  
...  
Keyword(s):  
Oxygen Vacancies ◽  
Uv Light ◽  
Light Exposure ◽  
Organic Dye ◽  
Photocatalytic Removal ◽  
Bi Nanoparticles

Concomitant formation of metallic Bi nanoparticles and oxygen vacancies was successfully achieved within Bi/BiOBr/RGO composites by green UV-light exposure.

scholarly journals Hydrophylicity Enhancement of Modified Cellulose Acetate Membrane to Improve the Membrane Performance in Produced Water Treatment

2018 ◽  
Vol 156 ◽  
pp. 08003 ◽  
Author(s):  
Tutuk Djoko Kusworo ◽  
Danny Soetrisnanto ◽  
Cynthia Santoso ◽  
Tyas Dwi Payanti ◽  
Dani Puji Utomo
Keyword(s):  
Water Treatment ◽  
Produced Water ◽  
Uv Light ◽  
Light Exposure ◽  
Membrane Surface ◽  
Asymmetric Structure ◽  
Dense Layer ◽  
Cellulose Acetate Membrane ◽  
Permeate Flux ◽  
Produced Water Treatment

Produced water is a wastewater generated from petroleum industry with high concentration of pollutants such as Total Dissolved Solid, Organic content, and Oil and grease. Membrane technology has been currently applied for produced water treatment due to its efficiency, compact, mild and clean process. The main problem of produced water using membrane is fouling on the membrane surface which causes on low permeate productivity. This paper is majority focused on the improvement of anti-fouling performance through several modifications to increase CA membrane hydrophilicity. The membrane was prepared by formulating the dope solution consists of 18 wt-% CA polymer, acetone, and PEG additive (3 wt-%, 5 wt-%, and 7 wt-%). The membranes are casted using NIPS method and being irradiated under UV light exposure. The SEM images show that parepared membrane has asymmetric structure consist of dense layer, intermediete layer, and finger-like support layer. The filtration test shows that PEG addition increase the membrane hydrophilicity and the permeate flux increases. UV light exposure on the membrane improves the membrane stability and hydrophilicity. The imrpovement of membrane anti-fouling performance is essential to achieve the higher productivity without lowering its pollutants rejection.

The effects of dexamethasone on bone fusion in an experimental model of posterolateral lumbar spinal arthrodesis

2001 ◽  
Vol 94 (1) ◽  
pp. 76-81 ◽  
Author(s):  
Paul D. Sawin ◽  
Curtis A. Dickman ◽  
Neil R. Crawford ◽  
M. Stephen Melton ◽  
William D. Bichard ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Bone Graft ◽  
Spinal Fusion ◽  
Experimental Model ◽  
Content Type ◽  
Bone Fusion ◽  
Group 12 ◽  
Spinal Arthrodesis ◽  
Lumbar Spinal ◽  
Fine Print

Object. The use of corticosteroid agents during the healing phase after spinal arthrodesis remains controversial. Although anecdotal opinion suggests that corticosteroids may inhibit bone fusion, such an effect has not been substantiated in clinical trials or laboratory investigations. This study was undertaken to delineate the effect of exogenous corticosteroid administration on bone graft incorporation in an experimental model of posterolateral lumbar fusion. Methods. An established, well-validated model of lumbar intertransverse process spinal fusion in the rabbit was used. Twenty-four adult New Zealand white rabbits underwent L5–6 bilateral posterolateral spinal fusion in which autogenous iliac crest bone graft was used. After surgery, the animals were randomized into two treatment groups: a control group (12 rabbits) that received intramuscular injections of normal saline twice daily and a dexamethasone group (12 rabbits) that received intramuscular dexamethasone (0.05 mg/kg) twice daily. After 42 days, the animals were killed and the integrity of the spinal fusions was assessed by radiography, manual palpation, and biomechanical testing. In seven (58%) of the 12 control rabbits, solid posterolateral fusion was achieved. In no dexamethasone-treated rabbits was successful fusion achieved (p = 0.003). Tensile strength and stiffness of excised spinal segments were significantly lower in dexamethasone-treated animals than in control animals (tensile strength 91.4 ± 30.6 N and 145.3 ± 48.2, respectively, p = 0.004; stiffness 31.4 ± 11.6 and 45.0 ± 15.2 N/mm, respectively, p = 0.02). Conclusions. The corticosteroid agent dexamethasone inhibited bone graft incorporation in a rabbit model of single-level posterolateral lumbar spinal fusion, inducing a significantly higher rate of nonunion, compared with that in saline-treated control animals.

scholarly journals A Left-Sided Prevalence of Lentigo Maligna: A UK Based Observational Study and Review of the Evidence

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Mark Gorman ◽  
Andrew Hart ◽  
Bipin Mathew
Keyword(s):  
Risk Factor ◽  
Uv Light ◽  
Light Exposure ◽  
Significant Risk ◽  
Significant Risk Factor ◽  
Evidence Base ◽  
The Body ◽  
Cumulative Exposure ◽  
Lentigo Maligna ◽  
Recent Trends

Skin cancer has been shown to present asymmetrically, prevalent on the left side of the body, more so in subtypes of cutaneous melanoma such as lentigo maligna. Biases have been linked to cumulative UV light exposure and automobile driving patterns. Though left-right ratios have previously correlated with the side men or women tend to position themselves or countries drive on, more recent trends indicate a consistent left-sided bias. To clarify reasons for changing trends, a review of the evidence base and LM’s laterality in a UK cohort (99 cases 2000–2011) was conducted for the first time. The strong correlation of left-sided excess, found in both genders (ratios 1.381–1.5,P<0.05  X20.841), is congruent with more recent findings. Though evidence indicates that driving position is no longer a risk factor for LM, due most likely to improved car window UV protection, it remains the most commonly attributed cause. Understanding phenomena such as UV lights “scatter effect” or that cumulative exposure may not be a significant risk factor helps rationalize older conclusions that would otherwise appear contradictory. The reasons for left-sided excess remain unclear but may be due to factors requiring further research such as the body’s anatomical/embryological asymmetry.

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