scholarly journals Numerical Evaluation on Residual Thermal Stress-Induced Delamination at PDMS–Metal Interface of Neural Prostheses

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 669
Author(s):  
Yuyang Mao ◽  
Ivan Pechenizkiy ◽  
Thomas Stieglitz ◽  
Theodor Doll
Keyword(s):  
Failure Mode ◽  
Elevated Temperatures ◽  
Standardized Test ◽  
Current Knowledge ◽  
Fem Simulation ◽  
Curing Temperature ◽  
Neural Implants ◽  
Test Procedures ◽  
Pdms Coating ◽  
Mechanisms Of Adhesion

The most common failure mode of implantable neural implants has been delamination of layers in compound structures and encapsulations in a wet body environment. Current knowledge of failure mechanisms of adhesion and its standardized test procedures are lacking and must be established. This study demonstrated a combined experimental and numerical method to investigate the residual stresses from one of the most common encapsulation materials, silicone rubber (polydimethylsiloxane-PDMS) during the coating process at elevated temperatures. Measured shrinkage of test specimen correlates well to a modified shrinkage model using thermal-mechanical finite element method (FEM) simulation. All simulated interfacial stresses show stress concentration at the PDMS coating front depending on curing temperature and coating thickness, while Griffith’s condition estimated the delamination of the coating front. This study emphasizes the understanding of the interfacial delamination giving the possibility to predict failure mode of neural interface.

Unique Archaeal Small RNAs

2018 ◽  
Vol 52 (1) ◽  
pp. 465-487 ◽  
Author(s):  
José Vicente Gomes-Filho ◽  
Michael Daume ◽  
Lennart Randau
Keyword(s):  
Noncoding Rna ◽  
Genome Rearrangement ◽  
Rna Binding ◽  
Elevated Temperatures ◽  
Rna Binding Proteins ◽  
Current Knowledge ◽  
Extreme Environments ◽  
Noncoding Rnas ◽  
Hyperthermophilic Archaea ◽  
Rna Modification

Advances in genome-wide sequence technologies allow for detailed insights into the complexity of RNA landscapes of organisms from all three domains of life. Recent analyses of archaeal transcriptomes identified interaction and regulation networks of noncoding RNAs in this understudied domain. Here, we review current knowledge of small, noncoding RNAs with important functions for the archaeal lifestyle, which often requires adaptation to extreme environments. One focus is RNA metabolism at elevated temperatures in hyperthermophilic archaea, which reveals elevated amounts of RNA-guided RNA modification and virus defense strategies. Genome rearrangement events result in unique fragmentation patterns of noncoding RNA genes that require elaborate maturation pathways to yield functional transcripts. RNA-binding proteins, e.g., L7Ae and LSm, are important for many posttranscriptional control functions of RNA molecules in archaeal cells. We also discuss recent insights into the regulatory potential of their noncoding RNA partners.

Aquatic testing guidelines insufficiently control the influence of dilution water toc and hardness on cationic polymer toxicity – A proposal to improve standardized test procedures

Chemosphere ◽  
2020 ◽  
Vol 259 ◽  
pp. 127473
Author(s):  
Edward R. Salinas ◽  
Jared S. Bozich ◽  
Sara Kolbenschlag ◽  
Miriam Kary-Heinrich ◽  
Philipp W. Hopp ◽  
...  
Keyword(s):  
Standardized Test ◽  
Cationic Polymer ◽  
Test Procedures ◽  
Dilution Water

A New Method for Measuring Adhesion of Vulcanized Rubber to Steel Cord at Elevated Temperatures

1977 ◽  
Vol 50 (1) ◽  
pp. 217-223 ◽  
Author(s):  
M. I. Dietrick ◽  
D. E. Emmert
Keyword(s):  
Elevated Temperatures ◽  
Experimental Sample ◽  
Sample Holder ◽  
Test Procedures ◽  
Vulcanized Rubber ◽  
Individual Unit ◽  
Wide Range ◽  
Steel Cord ◽  
Student’S T ◽  
The Individual

Abstract The analysis of variance of the elevated temperature tests conducted in this study showed that the experimental sample holder gave slightly higher values than tests run in an oven with the standard sample holder. However, this difference was less than 1% of the average adhesion value. Student's t-tests of the individual unit-to-unit comparison rated the test procedures equivalent over a wide range of temperature and aging histories. The advantages of this experimental sample holder are: 1. lower equipment costs; 2. rapid means of testing steel cord adhesion at elevated temperatures; 3. ease and simplicity of operation; 4. adaptability of the experimental holder to various tensile testing equipment.

Reliability of Miniature Concrete Prism Test in Assessing Alkali-Silica Reactivity of Moderately Reactive Aggregates

2020 ◽  
Vol 2674 (4) ◽  
pp. 23-29
Author(s):  
Harish Konduru ◽  
Prasad Rangaraju ◽  
Omar Amer
Keyword(s):  
False Positive ◽  
Standardized Test ◽  
False Negative ◽  
Test Method ◽  
Test Procedures ◽  
Concrete Prism ◽  
Coarse Aggregates ◽  
Fine Aggregates ◽  
Mortar Bar ◽  
Concrete Prism Test

Alkali-silica reaction (ASR) is one of the most significant durability issues in concrete structures. Although there are a number of standardized test procedures to evaluate the aggregate reactivity, each method has its own drawbacks. Two of the most common tests that are employed widely are the accelerated mortar bar test (AMBT) (ASTM C1260) and the concrete prism test (CPT) (ASTM C1293). The major issue with the AMBT test is the number of false-positive results from this test associated with high test temperature, rendering the test method unreliable. CPT is one of the most reliable tests for assessing the potential for ASR, but its major disadvantage is the duration of the test involved, which takes one to two years. In this research, a novel test method called the miniature concrete prism test (MCPT) was developed and the effectiveness and reliability of the results assessed when compared with CPT and AMBT. Samples of 26 coarse aggregates and 16 fine aggregates with various reactivity levels were employed for the testing. The test results were compared for MCPT versus CPT, in which 23 out of 26 coarse aggregates and eight out of 16 fine aggregates either passed or failed in both MCPT and CPT. For MCPT versus AMBT, 16 out of 26 coarse aggregates and 13 out of 16 fine aggregates either passed or failed in both MCPT and AMBT. The sensitivity of false-negative and false-positive aggregate sources is discussed and explained briefly.

scholarly journals Study on Tensile Properties of CFRP Plates under Elevated Temperature Exposure

Materials ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 1995 ◽  
Author(s):  
Yongxin Yang ◽  
Yanju Jiang ◽  
Hongjun Liang ◽  
Xiaosan Yin ◽  
Yue Huang
Keyword(s):  
Tensile Strength ◽  
Elastic Modulus ◽  
Elevated Temperature ◽  
Tensile Properties ◽  
Failure Mode ◽  
Elevated Temperatures ◽  
Strain Curve ◽  
Effect Of Temperature ◽  
Temperature Exposure ◽  
The Impact

Elevated temperature exposure has a negative effect on the performance of the matrix resin in Carbon Fiber Reinforced Plastics (CFRP) plates, whereas limited quantitative research focuses on the deteriorations. Therefore, 30 CFRP specimens were designed and tested under elevated temperatures (10, 30, 50, 70, and 90 °C) to explore the degradations in tensile properties. The effect of temperature on the failure mode, stress-strain curve, tensile strength, elastic modulus and elongation of CFRP plates were investigated. The results showed that elevated temperature exposure significantly changed the failure characteristics. When the exposed temperature increased from 10 °C to 90 °C, the failure mode changed from the global factures in the whole CFRP plate to the successive fractures in carbon fibers. Moreover, with temperatures increasing, tensile strength and elongation of CFRP plates decreases gradually while the elastic modulus shows negligible change. Finally, the results of One-Way Analysis of Variance (ANOVA) show that the degradation of the tensile strength of CFRP plates was due to the impact of elevated temperature exposure, rather than the test error.

scholarly journals Effect of curing temperature on the behaviour of UHPFRC at elevated temperatures

2018 ◽  
Vol 182 ◽  
pp. 670-681 ◽  
Author(s):  
Charles Kahanji ◽  
Faris Ali ◽  
Ali Nadjai ◽  
Naveed Alam
Keyword(s):  
Elevated Temperatures ◽  
Curing Temperature

Fabrication of a Cell Culture Plate With a Three-Dimensional Printed Mold and Thermal Analysis of PDMS-Based Casting Process

2018 ◽  
Vol 10 (6) ◽  
Author(s):  
Myo Min Zaw ◽  
William D. Hedrich ◽  
Timothy Munuhe ◽  
Mohamad Hossein Banazadeh ◽  
Hongbing Wang ◽  
...  
Keyword(s):  
Cell Culture ◽  
Temperature Distribution ◽  
Fused Deposition Modeling ◽  
Thermal Damage ◽  
Elevated Temperatures ◽  
Three Dimensional ◽  
Curing Temperature ◽  
Maximum Temperature ◽  
Maximum Temperature Difference ◽  
Fused Deposition

Abstract Polydimethylsiloxane (PDMS)-based casting method was used to fabricate PDMS cell culture platforms with molds printed by a fused deposition modeling (FDM) printer. Cell viability study indicated that the produced plates have the suitable biocompatibility, surface properties, and transparency for cell culture purposes. The molds printed from acrylonitrile-butadiene-syrene (ABS) were reusable after curing at 65 °C, but were damaged at 75 °C. To understand thermal damage to the mold at elevated temperatures, the temperature distribution in an ABS mold during the curing process was predicted using a model that considers conduction, convection, and radiation in the oven. The simulated temperature distribution was consistent with the observed mold deformation. As the maximum temperature difference in the mold did not change appreciably with the curing temperature, we consider that the thermal damage is due to the porous structure that increases the thermal expansion coefficient of the printed material. Our study demonstrated that FDM, an affordable and accessible three-dimensional (3D) printer, has great potential for rapid prototyping of custom-designed cell culture devices for biomedical research.

Sustainable Development of Concrete Using GGBS: Effect of Curing Temperatures on the Strength Development of Concrete

2015 ◽  
Vol 776 ◽  
pp. 3-8
Author(s):  
Gidion Turu'allo
Keyword(s):  
Sustainable Development ◽  
Portland Cement ◽  
Elevated Temperatures ◽  
Curing Temperature ◽  
Strength Development ◽  
Environmental Preservation ◽  
Cement Production ◽  
Granulated Blast Furnace Slag ◽  
C 50 ◽  
Emission Of Greenhouse Gases

The World Earth Summits in Rio de Janeiro, Brazil and Kyoto, Japan in 1992 and 1997 respectively, have made it clear that uncontrolled increased emission of greenhouse gases to the atmosphere is no longer environmentally and socially acceptable for sustainable development. The increase of cement production will affect the environmental preservation, natural conservation and increase the CO2emission, which is one of the primarily gases that contribute to the global warming. The use of ground granulated blast furnace slag (ggbs) to replace a part of Portland cement in concrete can reduce the CO2emission. It also can provide significant benefits to concrete properties, such as increase the workability and durability of concrete. The early strength of ggbs concretes that had been cured at standard curing temperature (20°C) were slower than that of concretes with Portland cement only, cured at the same temperature. However, there are some indications show that curing the ggbs concrete at elevated temperatures will significantly enhanced the early age strength of the concrete. The objectives of this research are to find out the effect of curing temperatures and levels replacement of Portland cement by ggbs on the strength development of concretes. The levels of ggbs to replace Portland cement were 0, 20, 35, 50 and 70%, while the curing temperatures were 20°C, 50°C and adiabatic curing. The concrete cubes were tested at ages: 6 and 12 hours, 1, 2, 4, 8, 16, 32, 64, 128, 256 and 365 days. The results showed that curing the ggbs concrete at temperatures higher than standard curing temperature, increased the strength development of the concrete at early ages.

Curing-Induced Distortion Mechanism in Adhesive Bonding of Aluminum AA6061-T6 and Steels

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
XiaoBo Zhu ◽  
YongBing Li ◽  
GuanLong Chen ◽  
Pei-Chung Wang
Keyword(s):  
Automotive Industry ◽  
Adhesive Bonding ◽  
Elevated Temperatures ◽  
Dissimilar Materials ◽  
Curing Temperature ◽  
Vehicle Body ◽  
Material System ◽  
Adhesive Properties ◽  
Adhesive Fracture ◽  
Strength Constraints

The bonding of dissimilar materials is of primary importance to the automotive industry as it enables designers the freedom to choose from a wide variety of low density materials such as aluminum and magnesium. However, when two dissimilar materials (e.g., aluminum-to-steel) are bonded by curing at elevated temperatures, residual stresses result upon cooling the layered material system to room temperature. Problems such as distortion and fracture of adhesive often emerge in bonding of these dissimilar materials for automotive applications. In this study, the transient distortion of riveted and rivet-bonded aluminum AA6061-T6-to-steels during the curing process was investigated using the photographic method. The influences of temperature, adhesive properties, adherend thickness, adherend strength, and the presence of constraints on the transient distortion and adhesive fracture were evaluated. The peak curing temperature was found to play the most important role in distortion and adhesive fracture, followed by the influence of adherends thickness. In contrast, the other parameters studied such as the adhesive strength, constraints' type, and adherend strength produced a limited effect on distortion. The results provide useful information about vehicle body structure's design in reducing the curing induced distortion.

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