Nanoscale Dynamic Viscoelastic Measurements at Elevated Temperature

2012 ◽  
Vol 1424 ◽  
Author(s):  
Jiping Ye ◽  
Satoshi Shimizu
Keyword(s):  
Surface Layer ◽  
Elastic Modulus ◽  
Elevated Temperatures ◽  
Thermal Protection ◽  
Measurement Data ◽  
Fused Silica ◽  
Polymer Materials ◽  
Small Scale ◽  
Nanoindentation Measurement ◽  
Significant Difference

ABSTRACTA nanoscale dynamic mechanical analysis (nano-DMA) measurement method has been successfully developed for use in evaluating nanoscale dynamic viscoelastic properties in small-scale polymer materials over a range of non-ambient temperatures from -120 oC to 500 oC. Measurements have been obtained with a nanoindentation measurement system, in which two key techniques are applied. One is a thermal protection system for control and prevention of thermal drift and noise. The other is an environmental control system for preventing corrosion at high temperatures and dew condensation at low temperatures. Measurement reliability was examined by using a combination of a thermal-mechanically stable fused silica and a homogeneous sample of isotropic polyethylene terephthalate (PET). Constant hardness and modulus values of the fused silica from -120 oC to 500 oC indicated that the measurements were not affected by thermal load drift and noise even at elevated temperatures. The PET sample exhibited no significant difference in temperature dispersions of storage elastic modulus, loss elastic modulus and loss tangent between the nanoindentation measurement data and bulk data measured with a conventional DMA method. A practical application involving surface-deteriorated polyethylene (PE) tubes was used to demonstrate the validity and usefulness of this nano-DMA method. Infrared spectroscopic imaging revealed that the surface layer of the PE tubes was oxidized to form a carbonylated (O=C<) layer. The storage elastic modulus and glass-transition temperature of the surface layer were much higher than the corresponding values of the interior. These data indicate a plausible reason for why the PE tube surface deteriorates to form brittle cracks.

Study of Small-Scale Friction at Elevated Temperatures

2005 ◽  
Author(s):  
Bo He ◽  
Q. Jane Wang ◽  
Yip-Wah Chung
Keyword(s):  
Carbon Steel ◽  
Friction Coefficient ◽  
Elevated Temperatures ◽  
Low Carbon Steel ◽  
Fused Silica ◽  
Small Scale ◽  
Low Carbon ◽  
Softening Effect ◽  
Surface Oxide Formation ◽  
Friction Measurements

This paper presents some preliminary results obtained from small-scale friction measurements from 25°C to 200°C on fused silica and 1018 low carbon steel surfaces. Friction transition phenomena were observed on the surfaces of fused silica and 1018 low carbon steel. The friction coefficient of the fused silica was found to be lower at higher temperature due to the material softening effect. However, the friction coefficient of the 1018 steel was found to be greater at high temperature which is likely the result of surface oxide formation.

Effect Of Elevated Temperatures On Complete Concrete Deformation Diagrams

2019 ◽  
pp. 9-14
Keyword(s):  
Experimental Data ◽  
Elastic Modulus ◽  
Elevated Temperatures ◽  
Peak Load ◽  
Relative Deformation ◽  
Deformation Characteristics ◽  
Compression Tests ◽  
Strain Behavior ◽  
Different Temperatures ◽  
Deformation Diagrams

The analysis of the previous results of the study on concrete stress-strain behavior at elevated temperatures has been carried out. Based on the analysis, the main reasons for strength retrogression and elastic modulus reduction of concrete have been identified. Despite a significant amount of research in this area, there is a large spread in experimental data received, both as a result of compression and tension. In addition, the deformation characteristics of concrete are insufficiently studied: the coefficient of transverse deformation, the limiting relative compression deformation corresponding to the peak load and the almost complete absence of studies of complete deformation diagrams at elevated temperatures. The two testing chambers provided creating the necessary temperature conditions for conducting studies under bending compression and tension have been developed. On the basis of the obtained experimental data of physical and mechanical characteristics of concrete at different temperatures under conditions of axial compression and tensile bending, conclusions about the nature of changes in strength and deformation characteristics have been drawn. Compression tests conducted following the method of concrete deformation complete curves provided obtaining diagrams not only at normal temperature, but also at elevated temperature. Based on the experimental results, dependences of changes in prism strength and elastic modulus as well as an equation for determining the relative deformation and stresses at elevated temperatures at all stages of concrete deterioration have been suggested.

Probing the Small-Scale Plasticity of an Icosahedral Quasicrystal I-Al-Pd-Mn at Elevated Temperatures

2020 ◽  
Author(s):  
Changjun Cheng ◽  
Yuan Xiao ◽  
Michel J.R. Haché ◽  
Zhiying Liu ◽  
Alla S. Sologubenko ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Small Scale ◽  
Icosahedral Quasicrystal

scholarly journals Improved Antioxidant Capacity of Black Tea Waste Utilizing PlantCrystals

Molecules ◽  
2021 ◽  
Vol 26 (3) ◽  
pp. 592 ◽  
Author(s):  
Abraham M. Abraham ◽  
Reem M. Alnemari ◽  
Jana Brüßler ◽  
Cornelia M. Keck
Keyword(s):  
Antioxidant Capacity ◽  
Aqueous Media ◽  
Natural Antioxidants ◽  
Black Tea ◽  
Pharmaceutical Products ◽  
Small Scale ◽  
Alternative Source ◽  
Significant Difference ◽  
Plant Waste

Antioxidants are recommended to prevent and treat oxidative stress diseases. Plants are a balanced source of natural antioxidants, but the poor solubility of plant active molecules in aqueous media can be a problem for the formulation of pharmaceutical products. The potential of PlantCrystal technology is known to improve the extraction efficacy and antioxidant capacity (AOC) of different plants. However, it is not yet proved for plant waste. Black tea (BT) infusion is consumed worldwide and thus a huge amount of waste occurs as a result. Therefore, BT waste was recycled into PlantCrystals using small-scale bead milling. Their characteristics were compared with the bulk-materials and tea infusion, including particle size and antioxidant capacity (AOC) in-vitro. Waste PlantCrystals possessed a size of about 280 nm. Their AOC increased with decreasing size according to the DPPH (1,1-diphenyl-2-picrylhydrazyl) and ORAC (oxygen radical absorbance capacity) assays. The AOC of the waste increased about nine-fold upon nanonization, leading to a significantly higher AOC than the bulk-waste and showed no significant difference to the infusion and the used standard according to DPPH assay. Based on the results, it is confirmed that the PlantCrystal technology represents a natural, cost-effective plant-waste recycling method and presents an alternative source of antioxidant phenolic compounds.

scholarly journals Nitric oxide (NO) in the Bohai Sea and the Yellow Sea

2019 ◽  
Vol 16 (22) ◽  
pp. 4485-4496 ◽  
Author(s):  
Ye Tian ◽  
Chao Xue ◽  
Chun-Ying Liu ◽  
Gui-Peng Yang ◽  
Pei-Feng Li ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Surface Layer ◽  
Yellow Sea ◽  
Bohai Sea ◽  
Limit Of Detection ◽  
Bottom Layer ◽  
The Yellow Sea ◽  
The Bohai Sea ◽  
Significant Difference ◽  
Average Flux

Abstract. Nitric oxide (NO) is a short-lived compound of the marine nitrogen cycle; however, our knowledge about its oceanic distribution and turnover is rudimentary. Here we present the measurements of dissolved NO in the surface and bottom layers at 75 stations in the Bohai Sea (BS) and the Yellow Sea (YS) in June 2011. Moreover, NO photoproduction rates were determined at 27 stations in both seas. The NO concentrations in the surface and bottom layers were highly variable and ranged from below the limit of detection (i.e., 32 pmol L−1) to 616 pmol L−1 in the surface layer and 482 pmol L−1 in the bottom layer. There was no significant difference (p>0.05) between the mean NO concentrations in the surface (186±108 pmol L−1) and bottom (174±123 pmol L−1) layers. A decreasing trend of NO in bottom-layer concentrations with salinity indicates a NO input by submarine groundwater discharge. NO in the surface layer was supersaturated at all stations during both day and night and therefore the BS and YS were a persistent source of NO to the atmosphere at the time of our measurements. The average flux was about 4.5×10-16 mol cm−2 s−1 and the flux showed significant positive relationship with the wind speed. The accumulation of NO during daytime was a result of photochemical production, and photoproduction rates were correlated to illuminance. The persistent nighttime NO supersaturation pointed to an unidentified NO dark production. NO sea-to-air flux densities were much lower than the NO photoproduction rates. Therefore, we conclude that the bulk of the NO produced in the mixed layer was rapidly consumed before its release to the atmosphere.

scholarly journals A Threat of Farmers’ Suicide and the Opportunity in Organic Farming for Sustainable Agricultural Development in India

2019 ◽  
Vol 11 (8) ◽  
pp. 2400 ◽  
Author(s):  
Karthikeyan Mariappan ◽  
Deyi Zhou
Keyword(s):  
Organic Farming ◽  
Tamil Nadu ◽  
Agricultural Development ◽  
Small Scale ◽  
Conventional Farming ◽  
Wide Range ◽  
Significant Difference ◽  
Small Scale Farmers ◽  
The Cost ◽  
Input Cost

Agriculture is the main sources of income for humans. Likewise, agriculture is the backbone of the Indian economy. In India, Tamil Nadu regional state has a wide range of possibilities to produce all varieties of organic products due to its diverse agro-climatic condition. This research aimed to identify the economics and efficiency of organic farming, and the possibilities to reduce farmers’ suicides in the Tamil Nadu region through the organic agriculture concept. The emphasis was on farmers, producers, researchers, and marketers entering the sustainable economy through organic farming by reducing input cost and high profit in cultivation. A survey was conducted to gather data. One way analysis of variance (ANOVA) has been used to test the hypothesis regards the cost and profit of rice production. The results showed that there was a significant difference in profitability between organic and conventional farming methods. It is very transparent that organic farming is the leading concept of sustainable agricultural development with better organic manures that can improve soil fertility, better yield, less input cost and better return than conventional farming. The study suggests that by reducing the cost of cultivation and get a marginal return through organic farming method to poor and small scale farmers will reduce socio-economic problems such as farmers’ suicides in the future of Indian agriculture.

Individual Versus Group Cognitive-Behavioral Therapy for Partner-Violent Men: A Preliminary Randomized Trial

2017 ◽  
Vol 35 (15-16) ◽  
pp. 2846-2868 ◽  
Author(s):  
Christopher M. Murphy ◽  
Christopher I. Eckhardt ◽  
Judith M. Clifford ◽  
Adam D. LaMotte ◽  
Laura A. Meis
Keyword(s):  
Cognitive Behavioral Therapy ◽  
Behavioral Therapy ◽  
Skills Training ◽  
Behavioral Approach ◽  
Cognitive Behavioral ◽  
Medium Effect ◽  
Individual Treatment ◽  
Small Scale ◽  
Relationship Functioning ◽  
Significant Difference

A randomized clinical trial tested the hypothesis that a flexible, case formulation–based, individual treatment approach integrating motivational interviewing strategies with cognitive-behavioral therapy (ICBT) is more efficacious than a standardized group cognitive-behavioral approach (GCBT) for perpetrators of intimate partner violence (IPV). Forty-two men presenting for services at a community domestic violence agency were randomized to receive 20 sessions of ICBT or a 20-week group cognitive-behavioral therapy (CBT) program. Participants and their relationship partners completed assessments of relationship abuse and relationship functioning at baseline and quarterly follow-ups for 1 year. Treatment uptake and session attendance were significantly higher in ICBT than GCBT. However, contrary to the study hypothesis, GCBT produced consistently equivalent or greater benefits than ICBT. Participant self-reports revealed significant reductions in abusive behavior and injuries across conditions with no differential benefits between conditions. Victim partner reports revealed more favorable outcomes for group treatment, including a statistically significant difference in psychological aggression, and differences exceeding a medium effect size for physical assault, emotional abuse, and partner relationship adjustment. In response to hypothetical relationship scenarios, GCBT was associated with greater reductions than ICBT (exceeding a medium effect) in articulated cognitive distortions and aggressive intentions. Treatment competence ratings suggest that flexible, individualized administration of CBT creates challenges in session agenda setting, homework implementation, and formal aspects of relationship skills training. Although caution is needed in generalizing findings from this small-scale trial, the results suggest that the mutual support and positive social influence available in group intervention may be particularly helpful for IPV perpetrators.

Facing extremes: archaeal surface-layer (glyco)proteins

Microbiology ◽  
2003 ◽  
Vol 149 (12) ◽  
pp. 3347-3351 ◽  
Author(s):  
Jerry Eichler
Keyword(s):  
Surface Layer ◽  
Structural Integrity ◽  
Elevated Temperatures ◽  
Protein Biosynthesis ◽  
Extreme Environments ◽  
Archaeal Protein ◽  
The Face ◽  
Micro Organisms ◽  
Physical Challenges ◽  
Insight Into

Archaea are best known in their capacities as extremophiles, i.e. micro-organisms able to thrive in some of the most drastic environments on Earth. The protein-based surface layer that envelopes many archaeal strains must thus correctly assemble and maintain its structural integrity in the face of the physical challenges associated with, for instance, life in high salinity, at elevated temperatures or in acidic surroundings. Study of archaeal surface-layer (glyco)proteins has thus offered insight into the strategies employed by these proteins to survive direct contact with extreme environments, yet has also served to elucidate other aspects of archaeal protein biosynthesis, including glycosylation, lipid modification and protein export. In this mini-review, recent advances in the study of archaeal surface-layer (glyco)proteins are discussed.

Structural Post-Fire Behaviour of the Steel I-Shape Beams-to-Cylindrical Columns

2012 ◽  
Vol 249-250 ◽  
pp. 1057-1062
Author(s):  
M. Zeinoddini ◽  
S.A. Hosseini ◽  
M. Daghigh ◽  
S. Arnavaz
Keyword(s):  
Structural Damage ◽  
Elevated Temperatures ◽  
Small Scale ◽  
Fire Tests ◽  
Fire Behaviour ◽  
Fire Event ◽  
Rescue Workers ◽  
Left Behind ◽  
Oil Platforms ◽  
In Fire

Previous researchers have tried to predict the response of different types of structures under elevated temperatures. The results are important in preventing the collapse of buildings in fire. Post-fire status of the structures is also of interest for ensuring the safety of rescue workers during the fire and in the post-fire situations. Determining the extent of the structural damage left behind a fire event is necessary to draw up adequate repair plans. Connections play an important role on the fire performance of different structures. Due to the high cost of fire tests, adequate experimental data about a broad range of connections is not available. A vulnerable type of such connections to fire is the weld connections between I-shape beams and cylindrical columns in oil platform topsides. Considering the high probability of fire in oil platforms, study of the behaviour of these connections at elevated temperatures and in the post-fire, is of great importance. In the current study, eight small scale experimental fire tests on welded connections between I-shape beams and cylindrical columns have been conducted. Four tests are aimed at investigating the structural performance of this connection at elevated temperature. In other tests, post-fire behaviour of these connections has been studied to investigate their residual structural strength.

Sign in / Sign up

Export Citation Format

Share Document