Evaluation of Polymers as Lubricants in the Extrusion of Aluminum

1982 ◽  
Vol 104 (4) ◽  
pp. 552-557 ◽  
Author(s):  
S. Suresh ◽  
S. Bahadur
Keyword(s):  
Yield Criterion ◽  
Film Formation ◽  
Normal Pressure ◽  
Velocity Fields ◽  
Powder Particle Size ◽  
Extrusion Force ◽  
Polymer Powder ◽  
Von Mises ◽  
Insight Into

The lubricating behavior of polytetrafluoroethylene, polyvinyl chloride, polychlorotrifluoroethylene, low density polyethylene, and high density polyethylene powders in the extrusion of 1100-0 aluminum has been investigated in terms of the extrusion force requirement and the quality of extrudate surface finish. Extrusion experiments which provided a measure of the extrusion force and friction force with varying ram travel were performed under both ambient and high temperature conditions. From these data the variation of coefficient of friction with ram travel and normal pressure has been calculated using the analysis based on von Mises’ yield criterion and spherical velocity fields. The effect of polymer powder particle size on the extrusion force was investigated. The extrudate surfaces were examined by scanning electron miscroscopy in order to study the film formation capability of polymers and to get an insight into the mechanism of polymer lubrication.

Attitudes of Elderly People in the South Moravian Region to Further Education

2014 ◽  
Vol 4 (2) ◽  
pp. 54-78
Author(s):  
Petr Adamec ◽  
Marián Svoboda
Keyword(s):  
Quality Of Life ◽  
Elderly People ◽  
Further Education ◽  
The South ◽  
The Third ◽  
Interesting Insight ◽  
Survey Results ◽  
Insight Into ◽  
Demographic Features

This paper deals with the results of sociological survey focused on identification of the attitudes of elderly people to further education. The research was carried out in September 2010. Experience of elderly people with further education, their readiness (determination) for further education as well as their motivation and barriers in further education were also subjects of this research. Detecting elderly population’s awareness of universities of the third age and finding out their further education preferences were an integral part of the research. Research sample consisted of citizens over 55 years living in the South Moravian region. The survey results are structured by socio-demographic features e.g.: age, sex, educational attainment etc. and provide an interesting insight into the attitudes of the target group to one of the activities that contributes to improvement of their quality of life.

Secondary normal pressure hydrocephalus in a patient with isolated frontal dilatation—an insight into pathophysiology?

2011 ◽  
Vol 154 (4) ◽  
pp. 769-772 ◽  
Author(s):  
James D. Shand Smith ◽  
Ahmed K. Toma ◽  
Laurence D. Watkins ◽  
Neil D. Kitchen
Keyword(s):  
Normal Pressure Hydrocephalus ◽  
Normal Pressure ◽  
Insight Into

scholarly journals Comparisons among rainbow trout, Oncorhynchus mykiss, populations of maternal transcript profile associated with egg viability

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Gregory M. Weber ◽  
Jill Birkett ◽  
Kyle Martin ◽  
Doug Dixon ◽  
Guangtu Gao ◽  
...  
Keyword(s):  
Rainbow Trout ◽  
Egg Quality ◽  
Transcript Abundance ◽  
Differentially Expressed ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Analysis Group ◽  
Maternal Transcripts ◽  
Single Batch ◽  
Insight Into

Abstract Background Transcription is arrested in the late stage oocyte and therefore the maternal transcriptome stored in the oocyte provides nearly all the mRNA required for oocyte maturation, fertilization, and early cleavage of the embryo. The transcriptome of the unfertilized egg, therefore, has potential to provide markers for predictors of egg quality and diagnosing problems with embryo production encountered by fish hatcheries. Although levels of specific transcripts have been shown to associate with measures of egg quality, these differentially expressed genes (DEGs) have not been consistent among studies. The present study compares differences in select transcripts among unfertilized rainbow trout eggs of different quality based on eyeing rate, among 2 year classes of the same line (A1, A2) and a population from a different hatchery (B). The study compared 65 transcripts previously reported to be differentially expressed with egg quality in rainbow trout. Results There were 32 transcripts identified as DEGs among the three groups by regression analysis. Group A1 had the most DEGs, 26; A2 had 15, 14 of which were shared with A1; and B had 12, 7 of which overlapped with A1 or A2. Six transcripts were found in all three groups, dcaf11, impa2, mrpl39_like, senp7, tfip11 and uchl1. Conclusions Our results confirmed maternal transcripts found to be differentially expressed between low- and high-quality eggs in one population of rainbow trout can often be found to overlap with DEGs in other populations. The transcripts differentially expressed with egg quality remain consistent among year classes of the same line. Greater similarity in dysregulated transcripts within year classes of the same line than among lines suggests patterns of transcriptome dysregulation may provide insight into causes of decreased viability within a hatchery population. Although many DEGs were identified, for each of the genes there is considerable variability in transcript abundance among eggs of similar quality and low correlations between transcript abundance and eyeing rate, making it highly improbable to predict the quality of a single batch of eggs based on transcript abundance of just a few genes.

A Study on the Mineral Depletion of the Foods Available to us as a Nation over the Period 1940 to 1991

2003 ◽  
Vol 17 (2) ◽  
pp. 85-115 ◽  
Author(s):  
David Thomas
Keyword(s):  
Mineral Content ◽  
Dietary Habits ◽  
Medical Research Council ◽  
Significant Loss ◽  
King's College ◽  
Compare And Contrast ◽  
Insight Into ◽  
Mineral Constituents ◽  
Mineral Depletion

In 1927 a study at King's College, University of London, of the chemical composition of foods was initiated by Dr McCance to assist with diabetic dietary guidance. The study evolved and was then broadened to determine all the important organic and mineral constituents of foods, it was financed by the Medical Research Council and eventually published in 1940. Over the next 51 years subsequent editions reflected changing national dietary habits and food laws as well as advances in analytical procedures. The most recent (5th Edition) published in 1991 has comprehensively analysed 14 different categories of foods and beverages. In order to provide some insight into any variation in the quality of the foods available to us as a nation between 1940 and 1991 it was possible to compare and contrast the mineral content of 27 varieties of vegetable, 17 varieties of fruit, 10 cuts of meat and some milk and cheese products. The results demonstrate that there has been a significant loss of minerals and trace elements in these foods over that period of time. It is suggested that the results of this study cannot be taken in isolation from recent dietary, environmental and disease trends. These trends are briefly mentioned and suggestions are made as to how the deterioration in the micronutrient quality of our food intake may be arrested and reversed.

scholarly journals Dialogical research to open up new narrative patterns among young women living with severe anxiety

2020 ◽  
Vol 30 (Supplement_5) ◽  
Author(s):  
L Cantarero Arevalo ◽  
S Fejfer Olsen
Keyword(s):  
Young Women ◽  
Population Group ◽  
Patient Experiences ◽  
Constructivist Approach ◽  
Patient’S Perspective ◽  
Healthcare Needs ◽  
Narrative Patterns ◽  
Severe Anxiety ◽  
Insight Into

Abstract Background 16,889 new cases of severe anxiety (SA) were diagnosed in Denmark in 2019. Incidence rate is highest among 16 to 24 year-old women, a population group with 64% risk of being diagnosed with SA. Experiences of stigma and shame are common among this group, affecting negatively their quality of life and opportunity to recover. The aim is 1) to gain insight into the digital narratives young women with SA share through social networking websites, and 2) to open up the possibility to develop new narrative patterns using dialogical research as a method rooted in Bakhtin (1895-1975) and further developed by Frank (2005). Methods Netnography of four large Facebook groups focused on anxiety was used to gain insight into the patients' narratives and to build guiding themes for the off-line dialogical interviews (DI). Biographical narrative patterns were analyzed in light of a narrative-constructivist approach. Participants were invited to sign an informed consent prior to the DI and received ample information about the project aims and their rights. Results 8 young women diagnosed with SA participated in the off-line DI. They had experienced stress, loss, betrayal or violation against them prior to the trigger of SA. All had constructed a narrative that explained why they were suffering from SA. Patient experiences were dominated by the struggle to control intrusive thoughts and to live in a threatening world. Some felt stigmatized and tried to hide their condition from colleagues, friends and family. They had different preferences regarding healthcare needs and were active in their search for alternative ways to cope with SA. Conclusions Participants perceived DI as beneficial. It thus has the potential to not only explore the patient's perspective in depth, but also serve as therapy during the process of inquiry. Key messages Dialogical research has the potential to not only explore the patient’s perspective in depth, but also serve as therapy during the process of inquiry. Young women suffering with severe anxiety experience shame and stigma, which worsen their condiction and hinder their opportunity to recover.

scholarly journals Earth’s Time-Variable Gravity from GRACE Follow-On K-Band Range-Rates and Pseudo-Observed Orbits

2021 ◽  
Vol 13 (9) ◽  
pp. 1766
Author(s):  
Igor Koch ◽  
Mathias Duwe ◽  
Jakob Flury ◽  
Akbar Shabanloui
Keyword(s):  
Gravity Field ◽  
Time Variable ◽  
Time Variable Gravity ◽  
Gravity Field Recovery ◽  
Variable Gravity ◽  
Earth’S System ◽  
Grace Mission ◽  
Insight Into ◽  
K Band

During its science phase from 2002–2017, the low-low satellite-to-satellite tracking mission Gravity Field Recovery And Climate Experiment (GRACE) provided an insight into Earth’s time-variable gravity (TVG). The unprecedented quality of gravity field solutions from GRACE sensor data improved the understanding of mass changes in Earth’s system considerably. Monthly gravity field solutions as the main products of the GRACE mission, published by several analysis centers (ACs) from Europe, USA and China, became indispensable products for quantifying terrestrial water storage, ice sheet mass balance and sea level change. The successor mission GRACE Follow-On (GRACE-FO) was launched in May 2018 and proceeds observing Earth’s TVG. The Institute of Geodesy (IfE) at Leibniz University Hannover (LUH) is one of the most recent ACs. The purpose of this article is to give a detailed insight into the gravity field recovery processing strategy applied at LUH; to compare the obtained gravity field results to the gravity field solutions of other established ACs; and to compare the GRACE-FO performance to that of the preceding GRACE mission in terms of post-fit residuals. We use the in-house-developed MATLAB-based GRACE-SIGMA software to compute unconstrained solutions based on the generalized orbit determination of 3 h arcs. K-band range-rates (KBRR) and kinematic orbits are used as (pseudo)-observations. A comparison of the obtained solutions to the results of the GRACE-FO Science Data System (SDS) and Combination Service for Time-variable Gravity Fields (COST-G) ACs, reveals a competitive quality of our solutions. While the spectral and spatial noise levels slightly differ, the signal content of the solutions is similar among all ACs. The carried out comparison of GRACE and GRACE-FO KBRR post-fit residuals highlights an improvement of the GRACE-FO K-band ranging system performance. The overall amplitude of GRACE-FO post-fit residuals is about three times smaller, compared to GRACE. GRACE-FO post-fit residuals show less systematics, compared to GRACE. Nevertheless, the power spectral density of GRACE-FO and GRACE post-fit residuals is dominated by similar spikes located at multiples of the orbital and daily frequencies. To our knowledge, the detailed origin of these spikes and their influence on the gravity field recovery quality were not addressed in any study so far and therefore deserve further attention in the future. Presented results are based on 29 monthly gravity field solutions from June 2018 until December 2020. The regularly updated LUH-GRACE-FO-2020 time series of monthly gravity field solutions can be found on the website of the International Centre for Global Earth Models (ICGEM) and in LUH’s research data repository. These operationally published products complement the time series of the already established ACs and allow for a continuous and independent assessment of mass changes in Earth’s system.

SUITABILITY OF ACID-SOLUBLE AND ACID-INSOLUBLE LEATHER FRACTIONS IN RADIOCARBON DATING

Radiocarbon ◽  
2020 ◽  
pp. 1-8
Author(s):  
Alyssa M Tate ◽  
Brittany Hundman ◽  
Jonathan Heile
Keyword(s):  
Radiocarbon Dating ◽  
Insoluble Fraction ◽  
Economic Life ◽  
Chemical Pretreatment ◽  
Acid Base ◽  
The Past ◽  
Acid Soluble Collagen ◽  
Method Of Production ◽  
Insight Into

ABSTRACT Leather has been produced by a variety of methods throughout human history, providing researchers unique insight into multiple facets of social and economic life in the past. Archaeologically recovered leather is often fragile and poorly preserved, leading to the use of various conservation and restoration efforts that may include the application of fats, oils, or waxes. Such additives introduce exogenous carbon to the leather, contaminating the specimen. These contaminants, in addition to those accumulated during interment, must be removed through chemical pretreatment prior to radiocarbon (14C) dating to ensure accurate dating. DirectAMS utilizes organic solvents, acid-base-acid (ABA) and gelatinization for all leather samples. Collagen yield from leather samples is variable due to the method of production and the quality of preservation. However, evaluating the acid-soluble collagen fraction, when available, provides the most accurate 14C dates for leather samples. In instances where gelatinization does not yield sufficient material, the resulting acid-insoluble fraction may be dated. Here we examine the effectiveness of the combined organic solvent and ABA pretreatment with gelatinization for leather samples, as well as the suitability of the acid-insoluble fraction for 14C dating.

Elasto-Plastic Stress Distribution in Triplate Joint Assembly under Bending Moment

2007 ◽  
Vol 345-346 ◽  
pp. 1437-1440
Author(s):  
Tae Hyun Baek ◽  
Seung Kee Koh ◽  
Jie Cheng
Keyword(s):  
Finite Element Method ◽  
Residual Stresses ◽  
Pure Aluminum ◽  
Main Tool ◽  
Bending Moment ◽  
The Finite Element Method ◽  
Shipbuilding Industry ◽  
Structural Parts ◽  
Von Mises

Pre-produced triplate transition joint assemblies are widely used in shipbuilding industry to make welds between aluminum and steel for a number of years now. The straight-shaped transition joint assemblies are bent during shipbuilding. So it is necessary to study the residual stresses created by punch forming, which would have heavy effects on the quality of structural parts. ABAQUS is a suite of powerful engineering simulation programs, based on the finite element method. In this paper, ABAQUS was used as the main tool to simulate the residual stresses in a triplate transition joint after unloading. Punch-pressing was carried to simulate bending moment in ABAQUS. The triplate is consisted of baselayer (steel: Lloyd’s Shipplate Gr. A), interlayer (pure aluminum: Al99.5) and superlayer (Al-Mg alloy: AlMg4.5Mn). Results from the ABAQUS analysis showed that increasing the radius of punch significantly reduced the von Mises residual stresses in steel. Changes of von Mises residual stresses in interlayer (Al99.5) and superlayer (AlMg4.5Mn) were negligible.

scholarly journals Nanostructured Strontium-Doped Calcium Phosphate Cements: A Multifactorial Design

2021 ◽  
Vol 11 (5) ◽  
pp. 2075
Author(s):  
Massimiliano Dapporto ◽  
Davide Gardini ◽  
Anna Tampieri ◽  
Simone Sprio
Keyword(s):  
Calcium Phosphate ◽  
Setting Time ◽  
Processing Parameters ◽  
High Energy ◽  
Powder Particle Size ◽  
Extrusion Force ◽  
Precise Control ◽  
Calcium Phosphate Cements ◽  
Shear Mixing ◽  
Mixing Techniques

Calcium phosphate cements (CPCs) have been extensively studied in last decades as nanostructured biomaterials for the regeneration of bone defects, both for dental and orthopedic applications. However, the precise control of their handling properties (setting time, viscosity, and injectability) still represents a remarkable challenge because a complicated adjustment of multiple correlated processing parameters is requested, including powder particle size and the chemical composition of solid and liquid components. This study proposes, for the first time, a multifactorial investigation about the effects of powder and liquid variation on the final performance of Sr-doped apatitic CPCs, based on the Design of Experiment approach. In addition, the effects of two mixing techniques, hand spatula (low-energy) and planetary shear mixing (high-energy), on viscosity and extrusion force were compared. This work aims to shed light on the various steps involved in the processing of CPCs, thus enabling a more precise and tailored design of the device, based on the clinical need.

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