Long-term Adhesion Studies of Polyimide to Inorganic and Metallic Layers

2012 ◽  
Vol 1466 ◽  
Author(s):  
Juan S. Ordonez ◽  
Christian Boehler ◽  
Martin Schuettler ◽  
Thomas Stieglitz
Keyword(s):  
Silicon Carbide ◽  
Accelerated Aging ◽  
Shear Tests ◽  
Adhesion Promoters ◽  
Intermediate Layers ◽  
Aging Conditions ◽  
Cause Of Failure ◽  
One Year ◽  
Inorganic Layers

ABSTRACTDelamination between thin-film metal and substrate is a major cause of failure in polyimide based neural microelectrode arrays. Chemical adhesion is the only way to establish a long-term bond that will allow two materials to stick to each other even in a wet environment, given that the materials do not deteriorate in the presence of water. This study assesses, by means of peel and shear tests, a long-term quantitative and comparative study of the adhesion of polyimide to various metallic and other inorganic layers of interest. Polyimide (BPDA-PPD) was cured on the layers, which involve platinum, gold and tungsten-titanium as commonly used implant metals and diamond-like carbon (DLC), silicon carbide (SiC), silicon dioxide (SiO2) and silicone nitride (SiN) as potential adhesion promoters to be used later as intermediate layers between metal and polyimide. The adhesion was observed over one year under accelerated-aging conditions by storing the specimens in 60°C saline (corresponding to 40000 hrs at 37°C). Only silicon carbide and amorphous carbon showed almost unaffected adhesion to polyimide over the testing period. No water intrusion at the interface was observed and the strong bond is almost fully maintained.

scholarly journals Resistance of a Silicone Membrane to Long-term UV and Moisture Aging in Light of Climate Change

2021 ◽  
Author(s):  
Jean-François Masson ◽  
Peter Collins ◽  
Marzieh Riahinezhad ◽  
Itzel Lopez-Carreon ◽  
Jocelyn Johansen
Keyword(s):  
Climate Change ◽  
Material Characterization ◽  
Room Temperature ◽  
Accelerated Aging ◽  
Building Envelope ◽  
Degradation Mechanisms ◽  
Aging Conditions ◽  
And Storage ◽  
Silicone Membranes

Three room-temperature fluid-applied silicone membranes intended for application in the building envelope were studied in this work. The membranes were subjected to 5000 hours of accelerated UV and moisture aging to evaluate their resistance to long-term aging. The properties of the membranes were studied to understand any degradation mechanisms that might happen during accelerated aging. The weight loss, wetting propensity, cracking and oxidation resistance, and storage modulus were measured at different intervals during the 5000 hours of aging. Based on the material characterization results, the silicone membranes proved to be resilient under aggressive accelerated UV radiation and moisture aging, conditions which can be expected as a result of climate change.

scholarly journals Investigation of 9000 hours multi-stress aging effects on High-Temperature Vulcanized Silicone Rubber with silica (nano/micro) filler hybrid composite insulator

PLoS ONE ◽  
2021 ◽  
Vol 16 (7) ◽  
pp. e0253372
Author(s):  
Arooj Rashid ◽  
Jawad Saleem ◽  
Muhammad Amin ◽  
Sahibzada Muhammad Ali ◽  
Aftab Ahmad Khan ◽  
...  
Keyword(s):  
High Temperature ◽  
Silicone Rubber ◽  
Breakdown Strength ◽  
Accelerated Aging ◽  
Environmental Stresses ◽  
Aging Effects ◽  
Nano Silica ◽  
Aging Conditions ◽  
Micro Silica

Degradation in the polymeric insulators is caused due to the environmental stresses. The main aim of this paper is to explore the improved aging characteristics of hybrid samples by adding nano/micro silica in High Temperature Vulcanized Silicone Rubber (HTV-SiR) under long term accelerated aging conditions for 9000 hours. As HTV-SiR is unable to sustain environmental stresses for a long time, thus a long term accelerated aging behavior is an important phenomenon to be considered for field application. The aging characteristics of nano/micro filled HTV-SiR are analyzed by using techniques such as Scanning Electron Microscopy (SEM), Leakage Current (LC), Fourier Transform Infrared Microscopy (FTIR), Hydrophobicity Classification (HC), and breakdown strength for the aging time of 9000 hours. FTIR and leakage currents are measured after every cycle. All the co-filled samples revealed escalated aging characteristics as compared to the neat sample except the SN8 sample (8% nano-silica+20% micro-silica) after 9000 hours of aging. The highest loading of 6% and 8% nano-silica with 20% micro-silica do not contribute to the improved performance when compared with the neat and hybrid samples. However, from the critical experimental analysis, it is deduced that SN2 sample (2% nano-silica+20% micro-silica) is highly resistant to the long term accelerated aging conditions. SN2 has no cracks, lower loss percentages in the important FTIR absorption peaks, higher breakdown strength and superior HC after aging as compared to the unfilled and hybrid samples.

scholarly journals A206 EVOLUTION OF PEDIATRIC AUTOIMMUNE CHOLANGITIS AND PRIMARY SCLEROSING CHOLANGITIS INTO ADULTHOOD

2021 ◽  
Vol 4 (Supplement_1) ◽  
pp. 234-236
Author(s):  
P Willems ◽  
J Hercun ◽  
C Vincent ◽  
F Alvarez
Keyword(s):  
Primary Sclerosing Cholangitis ◽  
Sclerosing Cholangitis ◽  
Response To Treatment ◽  
Similar Proportion ◽  
Autoimmune Cholangitis ◽  
Significant Difference ◽  
One Year ◽  
Liver Tests

Abstract Background The natural history of primary sclerosing cholangitis (PSC) in children seems to differ from PSC in adults. However, studies on this matter have been limited by short follow-up periods and inconsistent classification of patients with autoimmune cholangitis (AIC) (or overlap syndrome). Consequently, it remains unclear if long-term outcomes are affected by the clinical phenotype. Aims The aims of this is study are to describe the long-term evolution of PSC and AIC in a pediatric cohort with extension of follow-up into adulthood and to evaluate the influence of phenotype on clinical outcomes. Methods This is a retrospective study of patients with AIC or PSC followed at CHU-Sainte-Justine, a pediatric referral center in Montreal. All charts between January 1998 and December 2019 were reviewed. Patients were classified as either AIC (duct disease on cholangiography with histological features of autoimmune hepatitis) or PSC (large or small duct disease on cholangiography and/or histology). Extension of follow-up after the age of 18 was done for patients followed at the Centre hospitalier de l’Université de Montréal. Clinical features at diagnosis, response to treatment at one year and liver-related outcomes were compared. Results 40 patients (27 PSC and 13 AIC) were followed for a median time of 71 months (range 2 to 347), with 52.5% followed into adulthood. 70% (28/40) had associated inflammatory bowel disease (IBD) (78% PSC vs 54% AIC; p=0.15). A similar proportion of patients had biopsy-proven significant fibrosis at diagnosis (45% PSC vs 67% AIC; p=0.23). Baseline liver tests were similar in both groups. At diagnosis, all patients were treated with ursodeoxycholic acid. Significantly more patients with AIC (77% AIC vs 30 % PSC; p=0.005) were initially treated with immunosuppressive drugs, without a significant difference in the use of Anti-TNF agents (0% AIC vs 15% PSC; p= 0.12). At one year, 55% (15/27) of patients in the PSC group had normal liver tests versus only 15% (2/13) in the AIC group (p=0.02). During follow-up, more liver-related events (cholangitis, liver transplant and cirrhosis) were reported in the AIC group (HR=3.7 (95% CI: 1.4–10), p=0.01). Abnormal liver tests at one year were a strong predictor of liver-related events during follow-up (HR=8.9(95% CI: 1.2–67.4), p=0.03), while having IBD was not (HR=0.48 (95% CI: 0.15–1.5), p=0.22). 5 patients required liver transplantation with no difference between both groups (8% CAI vs 15% CSP; p=0.53). Conclusions Pediatric patients with AIC and PSC show, at onset, similar stage of liver disease with comparable clinical and biochemical characteristics. However, patients with AIC receive more often immunosuppressive therapy and treatment response is less frequent. AIC is associated with more liver-related events and abnormal liver tests at one year are predictor of bad outcomes. Funding Agencies None

scholarly journals “The Looming, Crazy Stalker Coronavirus”: Fear Mongering, Fake News, and the Diffusion of Distrust

2021 ◽  
Vol 7 ◽  
pp. 237802312110247
Author(s):  
Alexandrea J. Ravenelle ◽  
Abigail Newell ◽  
Ken Cai Kowalski
Keyword(s):  
Mental Health ◽  
Media Coverage ◽  
Media Consumption ◽  
Fake News ◽  
Compensatory Control ◽  
The Media ◽  
Good For ◽  
Fear Mongering ◽  
One Year

The authors explore media distrust among a sample of precarious and gig workers interviewed during the COVID-19 pandemic. Although these left-leaning respondents initially increased their media consumption at the outset of the pandemic, they soon complained of media sensationalism and repurposed a readily available cultural tool: claims of “fake news.” As a result, these unsettled times have resulted in a “diffusion of distrust,” in which an elite conservative discourse of skepticism toward the media has also become a popular form of compensatory control among self-identified liberals. Perceiving “fake news” and media sensationalism as “not good” for their mental health, respondents also reported experiencing media burnout and withdrawing from media consumption. As the pandemic passes its one-year anniversary, this research has implications for long-term media coverage on COVID-19 and ongoing media trust and consumption.

scholarly journals Short- and long-term effects of ponderosa pine fuel treatments intersected by the Egley Fire Complex, Oregon, USA

Fire Ecology ◽  
2019 ◽  
Vol 15 (1) ◽  
Author(s):  
Jessie M. Dodge ◽  
Eva K. Strand ◽  
Andrew T. Hudak ◽  
Benjamin C. Bright ◽  
Darcy H. Hammond ◽  
...  
Keyword(s):  
Prescribed Fire ◽  
Vegetation Cover ◽  
Tree Density ◽  
Tree Canopy ◽  
Fuel Treatments ◽  
Dead Tree ◽  
High Severity ◽  
Short And Long Term ◽  
One Year

Abstract Background Fuel treatments are widely used to alter fuels in forested ecosystems to mitigate wildfire behavior and effects. However, few studies have examined long-term ecological effects of interacting fuel treatments (commercial harvests, pre-commercial thinnings, pile and burning, and prescribed fire) and wildfire. Using annually fitted Landsat satellite-derived Normalized Burn Ratio (NBR) curves and paired pre-fire treated and untreated field sites, we tested changes in the differenced NBR (dNBR) and years since treatment as predictors of biophysical attributes one and nine years after the 2007 Egley Fire Complex in Oregon, USA. We also assessed short- and long-term fuel treatment impacts on field-measured attributes one and nine years post fire. Results One-year post-fire burn severity (dNBR) was lower in treated than in untreated sites across the Egley Fire Complex. Annual NBR trends showed that treated sites nearly recovered to pre-fire values four years post fire, while untreated sites had a slower recovery rate. Time since treatment and dNBR significantly predicted tree canopy and understory green vegetation cover in 2008, suggesting that tree canopy and understory vegetation cover increased in areas that were treated recently pre fire. Live tree density was more affected by severity than by pre-fire treatment in either year, as was dead tree density one year post fire. In 2008, neither treatment nor severity affected percent cover of functional groups (shrub, graminoid, forb, invasive, and moss–lichen–fungi); however, by 2016, shrub, graminoid, forb, and invasive cover were higher in high-severity burn sites than in low-severity burn sites. Total fuel loads nine years post fire were higher in untreated, high-severity burn sites than any other sites. Tree canopy cover and density of trees, saplings, and seedlings were lower nine years post fire than one year post fire across treatments and severity, whereas live and dead tree basal area, understory surface cover, and fuel loads increased. Conclusions Pre-fire fuel treatments effectively lowered the occurrence of high-severity wildfire, likely due to successful pre-fire tree and sapling density and surface fuels reduction. This study also quantified the changes in vegetation and fuels from one to nine years post fire. We suggest that low-severity wildfire can meet prescribed fire management objectives of lowering surface fuel accumulations while not increasing overstory tree mortality.

scholarly journals Is It Definitely Clear That Long-Term Survival after Breast Cancer Surgery Is Not Affected by Anaesthetics?

Cancers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 3390
Author(s):  
Mats Enlund
Keyword(s):  
Breast Cancer ◽  
Survival Data ◽  
Retrospective Studies ◽  
Breast Cancer Surgery ◽  
Breast Cancer Patients ◽  
Term Survival ◽  
Long Term Survival ◽  
Significant Difference ◽  
One Year

Retrospective studies indicate that cancer survival may be affected by the anaesthetic technique. Propofol seems to be a better choice than volatile anaesthetics, such as sevoflurane. The first two retrospective studies suggested better long-term survival with propofol, but not for breast cancer. Subsequent retrospective studies from Asia indicated the same. When data from seven Swedish hospitals were analysed, including 6305 breast cancer patients, different analyses gave different results, from a non-significant difference in survival to a remarkably large difference in favour of propofol, an illustration of the innate weakness in the retrospective design. The largest randomised clinical trial, registered on clinicaltrial.gov, with survival as an outcome is the Cancer and Anesthesia study. Patients are here randomised to propofol or sevoflurane. The inclusion of patients with breast cancer was completed in autumn 2017. Delayed by the pandemic, one-year survival data for the cohort were presented in November 2020. Due to the extremely good short-term survival for breast cancer, one-year survival is of less interest for this disease. As the inclusions took almost five years, there was also a trend to observe. Unsurprisingly, no difference was found in one-year survival between the two groups, and the trend indicated no difference either.

scholarly journals The first commercial use of the Valiant Navion stent graft system for endovascular repair of a descending thoracic aortic aneurysm

Vascular ◽  
2020 ◽  
pp. 170853812098112
Author(s):  
Cassra N Arbabi ◽  
Navyash Gupta ◽  
Ali Azizzadeh
Keyword(s):  
Stent Graft ◽  
Standard Of Care ◽  
Aortic Aneurysms ◽  
Descending Thoracic Aortic Aneurysm ◽  
Thoracic Aortic Aneurysms ◽  
Commercial Use ◽  
Early Results ◽  
Multiple Configuration ◽  
One Year

Objectives Thoracic endovascular aortic repair (TEVAR) is the standard of care for descending thoracic aortic aneurysms (DTAA), and newer generation stent grafts have significant design improvements compared to earlier generation devices. Methods We report the first commercial use of the Medtronic Valiant Navion stent graft for treatment of an 85-year-old woman with a 5.8 cm DTAA and a highly tortuous thoracic aorta. Results A percutaneous TEVAR was performed using a two-piece combination of the Valiant Navion FreeFlo and CoveredSeal stent graft configurations for zones 2–5 coverage. The devices were successfully delievered through highly tortuous anatomy and deployed, excluding the entire length of the aneurysm with precise landing, excellent apposition and no evidence of endoleak. The patient tolerated the procedure well and has had no stent graft-related complications through one-year follow-up. Conclusions Design enhancements such as a lower profile delivery system, better conformability, and a shorter tapered tip are some of the improvements to this third-generation TEVAR device. Coupled with the multiple configuration options available, this gives physicians a better tool to treat thoracic aortic pathologies in patients with challenging anatomy. The early results are encouraging, and evaluation of long-term outcomes will continue.

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