Rheological Measurements for the Characterization of High Polymers

1958 ◽  
Vol 31 (4) ◽  
pp. 681-690 ◽  
Author(s):  
Kurt Edelmann ◽  
Edith Horn
Keyword(s):  
Flow Curve ◽  
Scientific Practice ◽  
Flow Behavior ◽  
Material Constant ◽  
Absolute Value ◽  
Long Term Experience ◽  
High Polymers

Abstract Since the Umstätter structural viscometer represents the only viscometer that operates on the capillary principle, the most accurate measuring principle in viscometry, with a shear stress range above 104, this paper describes the necessary steps, from the long term experience of the authors with this apparatus, which permit a rapid and true determination of a complete flow curve. Also the necessary calculations are given and explained in an example. From this method, the critical velocity gradient G^, the inflection point of the flow curve, was obtained as a characteristic material constant, dependent only on the molecular weight of the high polymer and its absolute value for inhomogeneity. It is the hope of the authors that scientific practice for characterizing high polymers will increasingly refer to the flow behavior of (their) solutions by determining the flow curve.

The Absolute, Entirely Viscometric Determination of the Molecular Weight of high Polymers

1957 ◽  
Vol 30 (2) ◽  
pp. 470-486 ◽  
Author(s):  
K. Edelmann
Keyword(s):  
Molecular Weight ◽  
Average Molecular Weight ◽  
Absolute Value ◽  
Simple Measurement ◽  
The Absolute ◽  
Viscosity Determination ◽  
Numerical Knowledge ◽  
High Polymers

Abstract The utility of high polymers in all fields of application depends on the average molecular weight. In general, strength, elasticity and tear resistance under sudden stress increase with the molecular weight. On the contrary, processibility and solubility decrease with increasing molecular weight. The opposing requirements for quality and economy lead to the necessity of possessing as accurate a knowledge of the molecular weight as possible, to make certain that the molecular weight of a product is adequate for the requirements of a definite application. Normally, a simple measurement of viscosity will suffice as a test for the characterization of a definite product. The knowledge of the absolute value of the molecular weight is not required in the case where it is possible to arrange different samples in a correct series. However, in many cases a numerical knowledge of the molecular weight is desirable. In the case of the reactions of cellulose, e.g., it is often necessary to determine at what point decomposition occurs. Normally, this is not possible by means of a simple viscosity determination, since its standardization against absolute methods varies with the degree of substitution and the type of solvent. To this must be added, the causes for the occurrence of structural viscosity in solutions of linear macromolecules, which also make it necessary to determine the molecular weight for the evaluation of these high polymers.

scholarly journals DETERMINATION OF PERSONAL SIGNIFICANCE AND CONTENT OF VALUES

2020 ◽  
Vol 8 (4) ◽  
pp. 445-455
Author(s):  
A.M. Lesin ◽  
Keyword(s):  
Semantic Content ◽  
Test Methods ◽  
Self Reflection ◽  
Personal Significance ◽  
Scientific Schools ◽  
The Social ◽  
Psychological Structure ◽  
Long Term Experience

This article poses a problem associated with the difficulties of studying and identifying the motivational potential of the value sphere, as well as the discrepancy between the content of the same values in different people or in the same, but at different times. The article describes the results of a theoretical search associated with different approaches to understanding and studying values in different sciences and scientific schools. Also, the main variants of classifications of values and the ways of their formation in the direction of the personality in the process of ontogenesis are determined. The difficulties associated with the study of values with the help of tests, taking into account the social desirability and expectation of answers or the lack of self-reflection ability of the respondents, are described. The modern non-test methods and approaches to the study of the value sphere are analyzed, which make it possible to identify personally significant values and the level of their motivational potential. A method is proposed for determining the personal significance of values , as opposed to their reflec tive representation, using the magnitude of the conflict between the significance and the implementation of values. The long-term experience of using this method among various respondents is described. Variants of the destructive level of personal significance of some values are demonstrated. The possibilities and examples of the study of values in relation to the psychological structure of initiative are shown. The possibilities of content analysis in determining the content are illustrated, examples of different semantic content of the same values are given. It is concluded that, in addition to classical test methods, it is necessary to apply such methods as well, which will help to distinguish between value ideas and personal values proper, as well as to determine their content.

scholarly journals Some problems of characterization of a solid surface via the surface free energy changes

2017 ◽  
Vol 35 (7-8) ◽  
pp. 647-659 ◽  
Author(s):  
Emil Chibowski
Keyword(s):  
Contact Angle ◽  
Free Energy ◽  
Experimental Determination ◽  
Surface Free Energy ◽  
Solid Surface ◽  
Contact Angles ◽  
Absolute Value ◽  
Receding Contact

During the processes occurring at a solid surface, the changes in the surface free energy take place. The knowledge about surface free energy is very helpful for understanding the processes taking place on the surface. However, experimental determination of solid surface free energy is still not a fully solved problem. In this paper, some problems dealing with calculation of solid surface free energy from contact angle are discussed based on literature values of advancing and receding contact angles measured on four different fluoropolymers surface. The four approaches most often used for the calculation are described and especial focus on the approach in which both the advancing and receding contact angles is paid. It is concluded that using probing liquids the absolute value of solid surface free energy cannot be determined. However, the determined apparent values of the energy are very helpful to understand the conditions necessary for a given process to occur.

scholarly journals Characterization of PM10 Sampled on the Top of a Former Mining Tower by the High-Volume Wind Direction-Dependent Sampler Using INNA

Atmosphere ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 29
Author(s):  
Irena Pavlíková ◽  
Daniel Hladký ◽  
Oldřich Motyka ◽  
Konstantin N. Vergel ◽  
Ludmila P. Strelkova ◽  
...  
Keyword(s):  
Winter Season ◽  
Ground Level ◽  
High Volume ◽  
Limit Values ◽  
Health Quality ◽  
Health Quality Of Life

The PM10 concentrations in the studied region (Ostravsko-karvinská agglomeration, Czech Republic) exceed air pollution limit values in the long-term and pose a significant problem for human health, quality of life and the environment. In order to characterize the pollution in the region and identify the pollution origin, Instrumental Neutron Activation Analysis (INAA) was employed for determination of 34 elements in PM10 samples collected at a height of 90 m above ground level. From April 2018 to March 2019, 111 PM10 samples from eight basic wind directions and calm and two smog situations were sampled. The elemental composition significantly varied depending on season and sampling conditions. The contribution of three important industrial sources (iron and steelworks, cement works) was identified, and the long-range cross-border transport representing the pollution from the Polish domestic boilers confirmed the most important pollution inflow during the winter season.

scholarly journals Characterization of the Triacylglycerol Fraction of Italian and Extra-European Hemp Seed Oil

Foods ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 916
Author(s):  
Carmela Tringaniello ◽  
Lina Cossignani ◽  
Francesca Blasi
Keyword(s):  
Seed Oil ◽  
Principal Component ◽  
Stereospecific Analysis ◽  
Hemp Seed ◽  
Fa Composition ◽  
Chemical Descriptors ◽  
Triacylglycerol Fraction

Hemp seed oil (HSO) has received considerable attention for its health properties, especially due to unsaturated fatty acid (UFA) content. In this work, the triacylglycerol (TAG) fraction of Italian and Extra-European HSO was characterized by applying an enzymatic approach, based on the use of pancreatic lipase and sn-1,2-diacylglycerol kinase. This procedure allows determination of the intrapositional FA% composition of TAG. The results of the stereospecific analysis are useful for deepening knowledge on HSO nutritional aspects. The high percentage of UFA (88.3–89.9%), in particular essential FA (74.4–85.9%), of HSO samples in sn-2 position is important for long-term health effects, but also to enhance the use of this oil as a functional ingredient in food, cosmetic and nutraceutical fields. Furthermore, the results of total and intrapositional FA % compositions, subjected to principal component analysis, were able to differentiate HSO Italian samples from Extra-European ones. Based on the obtained results, it can be stated that the stereospecific analysis represents a potent analytical tool providing the fingerprint of TAG fraction, useful to highlight possible chemical descriptors for HSO authenticity and traceability purposes.

scholarly journals Influence of Specimen Age and Use of Different Negative Controls in Determination of Intracytoplasmic Levels of Cytokines after Whole-Blood Culture Assay

2002 ◽  
Vol 9 (2) ◽  
pp. 295-298 ◽  
Author(s):  
Christian Schultz ◽  
Christina Rott ◽  
Petra Temming ◽  
Julia von Puttkammer ◽  
Peter Bucsky
Keyword(s):  
Interleukin 6 ◽  
Interleukin 2 ◽  
Gamma Interferon ◽  
Interleukin 8 ◽  
Long Term Storage ◽  
Substantial Decline ◽  
Negative Controls

ABSTRACT Intracytoplasmic detection of cytokines by flow cytometry has become a powerful tool in the characterization of cytokine-producing cells. However, it is not known to what extent specimen age and the use of various negative controls may influence the amount of cytokine-positive cells. We therefore compared different times of storage and the use of several negative controls in the determination of intracytoplasmic levels of cytokines. There was a substantial decline of interleukin-2- and gamma interferon-positive lymphocytes after 20 h and especially after 48 h of storage. The precision of intracytoplasmic interleukin-6 determination decreases after long-term storage compared to 2 h of storage, whereas the amount of interleukin-8-positive monocytes remained rather stable. Therefore, we recommend performing the analysis as fast as possible after the blood sample is drawn. Under consideration of isotype-matched antibodies and nonstimulated cells as negative controls instead of the purified antibody-blocking control, strikingly higher amounts of interleukin-2-, gamma interferon, interleukin-6-, and interleukin-8-positive cells were found. For a meaningful interpretation of data these differences have to be kept in mind. Further studies should evaluate the exact specificity of these controls.

scholarly journals Lance Design for Scrap Melting Aggregates

2021 ◽  
Vol 15 (1) ◽  
pp. 162-167
Author(s):  
Ladislav Kovar ◽  
Pavel Novak ◽  
Tomas Hapla
Keyword(s):  
Operational Reliability ◽  
Bath Surface ◽  
Scrap Melting ◽  
Gaseous Media ◽  
Design Systems ◽  
Design Characteristics ◽  
The Individual ◽  
Long Term Experience

Metallurgical aggregates, which are used for metal waste melting, are equipped with lances for blowing gaseous media. These gaseous media allow especially scrap melting and intense homogenization of the resulting melt. In connection with this, the blowing systems are developed both for blowing of gaseous media itself on the bath surface or into the melt and for blowing of the gas mixture with powdered substances. When designing the blowing systems and the individual lance tips and nozzles, it is necessary to respect certain criteria, the derivation of which is based on long-term experience and acquired knowledge in this field. The submitted paper summarizes the design recommendations, including the determination of the selected design characteristics of the nozzles for blowing gaseous media on the bath surface in the metallurgical aggregate. These design characteristics help designers and engineers to design systems that meet the high demands on quality, efficiency and operational reliability.

Modification and Characterization of the Surface of SOI Nanowire Sensors

2012 ◽  
Vol 18-19 ◽  
pp. 139-147 ◽  
Author(s):  
O.V. Naumova ◽  
B.I. Fomin ◽  
N.F. Malyarenko ◽  
V.P. Popov
Keyword(s):  
Surface Density ◽  
Protein Detection ◽  
Surface Treatments ◽  
Silicon On Insulator ◽  
Long Term Storage ◽  
Protein Bovine Serum Albumin ◽  
Term Storage

In the present study, the pursued purposes were: (i) monitoring the electrical properties of silicon-on-insulator nanowires (SOI NWs), (ii) determination of surface treatments suitable for obtaining reproducible states on the surface of SOI NWs after their long-term storage, and (iii) identification of surface treatments suitable for regenerating the NW surface after protein (bovine serum albumin molecules) detection. It is shown that, during storage, with the passage of time a negative effective charge was accumulated on the surface of n-SOI NWs up to surface density Qeff = (2-4)х1012 cm-2, while the interface states at the NW/SiO2 interface underwent relatively slow depassivation. Treatments in H2O2 with subsequent treatments in HF can be used for removing organic contaminations from the NW surface and for regenerating the initial working state of SOI NWs after protein detection.

Preparation And elemental analysis of ancient fibers

1987 ◽  
Vol 45 ◽  
pp. 410-411
Author(s):  
Allen Angel ◽  
Kathryn A. Jakes
Keyword(s):  
Cross Sections ◽  
Physical Structure ◽  
Energy Dispersive ◽  
Archaeological Sites ◽  
X Ray ◽  
Long Term Storage ◽  
Backscattered Electron ◽  
Electron Imaging

Fabrics recovered from archaeological sites often are so badly degraded that fiber identification based on physical morphology is difficult. Although diagenetic changes may be viewed as destructive to factors necessary for the discernment of fiber information, changes occurring during any stage of a fiber's lifetime leave a record within the fiber's chemical and physical structure. These alterations may offer valuable clues to understanding the conditions of the fiber's growth, fiber preparation and fabric processing technology and conditions of burial or long term storage (1).Energy dispersive spectrometry has been reported to be suitable for determination of mordant treatment on historic fibers (2,3) and has been used to characterize metal wrapping of combination yarns (4,5). In this study, a technique is developed which provides fractured cross sections of fibers for x-ray analysis and elemental mapping. In addition, backscattered electron imaging (BSI) and energy dispersive x-ray microanalysis (EDS) are utilized to correlate elements to their distribution in fibers.

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