Microstructural Analysis of a Polypropylene Geotextile After Long-Term Outdoor Exposure

2009 ◽  
pp. 335-335-17 ◽  
Author(s):  
LG Tisinger ◽  
ID Peggs ◽  
BE Dudzik ◽  
JP Winfree ◽  
CE Carraher
Keyword(s):  
Microstructural Analysis ◽  
Outdoor Exposure

scholarly journals Degradation of welded joint made of T91 steel with different additional materials

2019 ◽  
Vol 91 (7) ◽  
pp. 55-60 ◽  
Author(s):  
Klaudia Klimaszewska ◽  
Kwiryn Wojsyk ◽  
Grzegorz Golański
Keyword(s):  
Annealing Time ◽  
Welded Joints ◽  
Welded Joint ◽  
Microstructural Analysis ◽  
Hardness Testing ◽  
Dissimilar Welded Joint

The aim of the research was to analyse the processes of degradation observed in a dissimilar welded joint of T91 steel. The analysis was performed for welded joints after long-term annealing for up to 8000 hours at the temperature of 600oC. Microstructural analysis and hardness testing were performed. The purpose of the tests was to evaluate the effect of annealing time at the temperature of ageing on formation and properties of the decarburized zone in the inter-bead area of the welded joint.The aim of the research was to analyse the processes of degradation observed in a dissimilar welded joint of T91 steel. The analysis was performed for welded joints after long-term annealing for up to 8000 hours at the temperature of 600oC. Microstructural analysis and hardness testing were performed. The purpose of the tests was to evaluate the effect of annealing time at the temperature of ageing on formation and properties of the decarburized zone in the inter-bead area of the welded joint.

Matrix Microstructural Analysis

2010 ◽  
pp. 211-222
Keyword(s):  
High Temperature ◽  
Natural Fiber ◽  
Fiber Composite ◽  
Microstructural Analysis ◽  
Fiber Reinforced Composites ◽  
Matrix Composites ◽  
Thermoplastic Matrix ◽  
Carbon Fiber Reinforced Composites ◽  
Natural Fiber Composite

Abstract Microstructural analysis of the composite matrix is necessary to understand the performance of the part and its long-term durability. This chapter focuses on the microstructural analysis of engineering thermoplastic-matrix composites and the influence of cooling rate and nucleation on the formation of spherulites in high-temperature thermoplastic-matrix carbon-fiber-reinforced composites. It also describes the microstructural analysis of a bio-based thermosetting-matrix natural fiber composite system.

scholarly journals “Smart” Triiodide Compounds: Does Halogen Bonding Influence Antimicrobial Activities?

Pathogens ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 182 ◽  
Author(s):  
Edis ◽  
Haj Bloukh ◽  
Abu Sara ◽  
Bhakhoa ◽  
Rhyman ◽  
...  
Keyword(s):  
Antimicrobial Agents ◽  
Biological Activities ◽  
Microstructural Analysis ◽  
Halogen Bonding ◽  
Antibacterial Activities ◽  
Antimicrobial Activities ◽  
One Pot ◽  
Long Term Stability ◽  
Free Iodine

Antimicrobial agents containing symmetrical triiodides complexes with halogen bonding may release free iodine molecules in a controlled manner. This happens due to interactions with the plasma membrane of microorganisms which lead to changes in the structure of the triiodide anion. To verify this hypothesis, the triiodide complex [Na(12-crown-4)2]I3 was prepared by an optimized one-pot synthesis and tested against 18 clinical isolates, 10 reference strains of pathogens and five antibiotics. The antimicrobial activities of this symmetrical triiodide complex were determined by zone of inhibition plate studies through disc- and agar-well-diffusion methods. The triiodide complex proved to be a broad spectrum microbicidal agent. The biological activities were related to the calculated partition coefficient (octanol/water). The microstructural analysis of SEM and EDS undermined the purity of the triiodide complex. The anionic structure consists of isolated, symmetrical triiodide anions [I-I-I]- with halogen bonding. Computational methods were used to calculate the energy required to release iodine from [I-I-I]- and [I-I···I]-. The halogen bonding in the triiodide ion reduces the antibacterial activities in comparison to the inhibitory actions of pure iodine but increases the long term stability of [Na(12-crown-4)2]I3.

scholarly journals Analyzing Near-Surface Regions of Hydrophobic and Long-Term Weathered Natural Stones at Microscopic Scale

Heritage ◽  
2020 ◽  
Vol 3 (2) ◽  
pp. 457-473
Author(s):  
Franziska Braun ◽  
Jeanette Orlowsky ◽  
Stefan Brüggerhoff
Keyword(s):  
Structural Changes ◽  
Color Difference ◽  
Outdoor Exposure ◽  
Material Surface ◽  
Building Structures ◽  
Near Surface ◽  
Visual Appearance ◽  
Microscopic Scale ◽  
Surface Damages

The visual appearance of building structures is an important attribute which reflects the character and identity of a region. Due to the influence of weathering, the surfaces of building stones alter, leading to aesthetic changes of the material surface such as discoloration or darkening. In this study, near-surface regions of weathered Baumberger (BST), Schleeriether (SST), and Obernkirchener Sandstones (OKS) have been analyzed at the microscopic scale in order to investigate the intensity and the extent of visual as well as structural changes and how both can be affected due to the presence of surface treatments with hydrophobing agents. It could be detected that aesthetic changes appeared already after 2 years of outdoor exposure, with the slightest variations on BST surfaces, followed by SST and OKS. The use of hydrophobing agents leads to a reduction in surface darkening in the short term. After long-term weathering, no significant changes are visible, as similar values in total color difference (ΔE*) were measured. Biogenic growth and the formation of black weathering crusts are the main reasons for color alterations in the case of the examined stones. The surface damages occur especially on calcareous (BST) followed by clayey (SST) and quartzitic (OKS) stone surfaces.

Crystal chemistry of clinker relicts from aged cementitious materials

2014 ◽  
Vol 47 (5) ◽  
pp. 1626-1637 ◽  
Author(s):  
Michele Secco ◽  
Luca Peruzzo ◽  
Laurie Palasse ◽  
Gilberto Artioli ◽  
Alberto Viani ◽  
...  
Keyword(s):  
Electron Backscatter Diffraction ◽  
Microstructural Analysis ◽  
Chemical Properties ◽  
Cementitious Materials ◽  
Operating Conditions ◽  
General Tendency ◽  
Hydration Kinetics ◽  
Definition Of ◽  
Backscatter Diffraction

Despite the general tendency to consider Portland cement virtually fully hydrated within a few years, the occurrence of non-reacted clinker phases in cementitious materials that are several decades old is rather common. In this work, the integration of microstructural analysis by scanning electron microscopy and quantitative microchemical and micromineralogical characterization techniques, such as electron microprobe analysis and electron backscatter diffraction, allowed the definition of the crystal-chemical properties of partially hydrated cement residuals within different types of aged cementitious materials. The results on several clinker relicts show that the calcium silicate phases are transformed systematically and pervasively by hydration reactions, whereas the aluminate and ferrite phases do frequently persist in the anhydrous state. These relict phases may be distinguished through their peculiar chemical, mineralogical and textural features. These observations raise interesting questions concerning the long-term hydration kinetics of clinker phases and the durability behaviour of cementitious materials in operating conditions.

High Temperature Oxidation and Corrosion of Silicon-Based Non-Oxide Ceramics

1999 ◽  
Vol 122 (1) ◽  
pp. 13-18 ◽  
Author(s):  
H. Klemm ◽  
M. Herrmann ◽  
C. Schubert
Keyword(s):  
High Temperature ◽  
Elevated Temperatures ◽  
Microstructural Analysis ◽  
Temperature Stability ◽  
Ambient Air ◽  
High Temperature Stability ◽  
Temperature Oxidation ◽  
Sic Ceramics ◽  
Silicon Based

The present study is focussed on the oxidation behavior of nonoxide silicon-based ceramics. Various Si3N4 and SiC ceramics were examined after long term oxidation tests (up to 5000 h) at 1500°C in ambient air. The damage mechanisms were discussed on the basis of a comprehensive chemical and microstructural analysis of the materials after the oxidation tests. The diffusion of oxygen into the material and its further reaction in the bulk of the material were found to be the most critical factors during long term oxidation treatment at elevated temperatures. However, the resulting damage in the microstructure of the materials can be significantly reduced by purposeful microstructural engineering. Using Si3N4/SiC and Si3N4/MoSi2 composite materials provides the possibility to improve the high temperature stability. [S0742-4795(00)00301-X]

scholarly journals Long-Term Creep-Rupture Behavior of Inconel® 740 and Haynes® 282

2014 ◽  
Author(s):  
P. F. Tortorelli ◽  
H. Wang ◽  
K. A. Unocic ◽  
M. L. Santella ◽  
J. P. Shingledecker ◽  
...  
Keyword(s):  
Deformation Behavior ◽  
Microstructural Analysis ◽  
Time Dependent ◽  
Steam Boiler ◽  
Power Law Model ◽  
Inconel Alloy ◽  
Term Creep ◽  
Modified Power Law ◽  
Rupture Behavior

Creep testing and microstructural analysis were used to assess the properties and time-dependent deformation behavior of precipitation-strengthened nickel-based alloys, specifically, Inconel® alloy 740 and Haynes® 282® alloy, for use as pressure components in boilers operating under advanced steam conditions (750°C, >35 MPa). In support of the need for extended service of steam boiler tubing, piping and vessels, the ability of simple Larson-Miller estimates and a modified power-law model (Wilshire et al.) to predict creep lifetimes on the order of 105 hours based on experimental data out to almost 50,000 h was evaluated for these alloys. Even under conservative conditions, both Inconel alloy 740 and Haynes 282 project to have creep lifetimes exceeding 100,000 hours at 750°C and 100 MPa. Paper published with permission.

Long-term alkali-silica mitigation of high-alkali concrete with cement replacements

2021 ◽  
pp. 1-29
Author(s):  
Douglas Hooton ◽  
Benoit Fournier
Keyword(s):  
Cementitious Materials ◽  
Outdoor Exposure ◽  
Supplementary Cementitious Materials ◽  
Concrete Prism ◽  
Different Temperatures ◽  
Concrete Blocks ◽  
High Alkali ◽  
Mortar Bar ◽  
The Impact

The impact of high-alkali Portland cements on the prescribed level of supplementary cementitious materials required in the Canadian standard for akali-silica reaction mitigation was evaluated. Based on the results, for concretes containing aggregates exhibiting moderate reactivity, the maximum allowable cement alkali limit was raised from 1.00% to 1.15%. For all levels of aggregate reactivity, cement alkali contents could be allowed up to 1.25% provided the recommended level of mitigation by supplementary cementitious materials was increased. In the initial laboratory study, mortar bars and concrete prisms were cast and monitored using two different reactive aggregates and recommended levels of fly ash and slag. For the concrete prism tests, the alkali contents of the cements were increased to 1.25%, as per the standard, or were increased by 0.25%. Instrumented outdoor exposure concrete blocks, along with additional concrete prisms stored at different temperatures, were cast from numerous mixtures made with cement alkali equivalents ranging up to 1.22%. This paper report on the long-term performance of the prisms and concrete blocks after 12 and 27 years. The performance of the outdoor blocks is also compared to predicted performance based on the accelerated mortar bar and concrete prism test results.

scholarly journals LONG-TERM OUTDOOR EXPOSURE TEST ON THE RATE OF CORROSION OF REINFORCING BAR IN CONCRETE CONTAINING CHLORIDE ION

2012 ◽  
Vol 77 (672) ◽  
pp. 143-151 ◽  
Author(s):  
Masaru KAKEGAWA ◽  
Yoshihiro MASUDA ◽  
Yuji MATSUBAYASHI ◽  
Tadatsugu KAGE
Keyword(s):  
Chloride Ion ◽  
Outdoor Exposure ◽  
Exposure Test ◽  
Reinforcing Bar ◽  
Outdoor Exposure Test

scholarly journals Nature Prescriptions for Health: A Review of Evidence and Research Opportunities

2020 ◽  
Vol 17 (12) ◽  
pp. 4213 ◽  
Author(s):  
Michelle C. Kondo ◽  
Kehinde O. Oyekanmi ◽  
Allison Gibson ◽  
Eugenia C. South ◽  
Jason Bocarro ◽  
...  
Keyword(s):  
Health Outcomes ◽  
Patient Adherence ◽  
Empirical Studies ◽  
Outdoor Exposure ◽  
Children And Families ◽  
Target Populations ◽  
At Risk Children ◽  
Short And Long Term ◽  
Provider Participation

Nature prescription programs have emerged to address the high burden of chronic disease and increasingly sedentary and screen-based lifestyles. This study examines the base of evidence regarding such programs. We conducted a narrative review of published literature using four electronic databases. We included case studies, research design articles, and empirical studies that discussed any type of outdoor exposure or activities initiated by a health-care provider from an outpatient clinic. We examined articles for information on target populations, health outcomes, and structural and procedural elements. We also summarized evidence of the effectiveness of nature prescription programs, and discussed needs and challenges for both practice and research. Eleven studies, including eight empirical studies, have evaluated nature prescription programs with either structured or unstructured formats, referring patients either to nearby parks or to formal outdoor activity programs. Empirical studies evaluate a wide variety of health behaviors and outcomes among the most at-risk children and families. Research is too sparse to draw patterns in health outcome responses. Studies largely tested program structures to increase adherence, or patient follow-through, however findings were mixed. Three published studies explore providers’ perspectives. More research is necessary to understand how to measure and increase patient adherence, short and long-term health outcomes for patients and their families, and determinants of provider participation and participation impacts on providers’ own health.

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