The Role of Surface Phenomena in Modified Cement Dispersions at Studying Poly-Functional Modifiers' Mechanism of Action

2020 ◽  
Vol 299 ◽  
pp. 1038-1043
Author(s):  
Mikhail M. Kosukhin ◽  
Andrei M. Kosukhin
Keyword(s):  
Solid Solution ◽  
Surface Tension ◽  
Chemical Composition ◽  
Phase Boundary ◽  
Disperse Phase ◽  
Surface Activity ◽  
Mechanism Of Action ◽  
Organic Substances ◽  
Molecular Weights

The research findings of colloid and chemical properties of poly-functional modifiers (PFM) with various chemical compositions and qualitative and quantitative proportions of polar organic substances with various molecular weights have been presented. The possibility of regulating the properties of PFM and concrete mixes, modified by them by means of not only changing the chemical composition of modifiers, but combining the types and quantity of active admixtures of polar organic substances with various molecular weights has been shown. It has been demonstrated that the modifiers under study possess the surface activity at solid-solution phase boundary, reducing the surface tension σsolid-liquid (σs-l) At the same time the surface tension at the solution-air phase boundary can remain the same or reduce to a certain extent depending on the modifier’s chemical composition. PFM and superplasticizer (SP) SB-3, which have, unlike SP S-3, the certain surface activity at solid-solution boundary, increase the air entrainment into concrete mix by 0.5÷1.5%, additionally increasing the freeze-thaw resistance of concretes of both fluid and equal-workable compositions without affecting their strength. The adsorption of modifiers on the disperse phase of suspension is conditioned by dispersion forces and, independently of its kind, is of monomolecular nature. For the localization of PFM molecules on the surface of a particle, its molecule should have a system of bonded aromatic rings or conjugated double bonds. The adsorbed modifier’s molecules should make the disperse phase surface hydrophilic and for this purpose they should contain hydrophilic groups along the full length. All this predetermines the role of adsorption-solvation factor in modifiers’ mechanism of action.

Prospects for surfactant peat derivatives

2021 ◽  
Author(s):  
Valerya Tatarintseva ◽  
Marina Trufanova ◽  
Svetlana Selyanina ◽  
Olga Yarygina ◽  
Ivan Zubov
Keyword(s):  
Surface Tension ◽  
Surface Layer ◽  
Chemical Composition ◽  
Humic Substances ◽  
Surface Activity ◽  
High Surface ◽  
Scattering Method ◽  
Water Interface ◽  
High Biological Activity ◽  
Group Chemical

<p>Peat is a caustobiolith traditionally used as a renewable source of organic substances, in particular humic substances (HS). They are considered to have high biological activity and therefore are widely used in industry and agriculture.</p><p>Geoclimatic conditions have a significant impact on the peat accumulation process. Accordingly, peat from various regions differs in composition and physicochemical characteristics of the main components. This affects the properties of peat-based products.</p><p>The study of the group chemical composition of high-moor peat from different climatic regions (Western Siberia and the Belomor-Kuloy plateau) was performed according to the certified author’s method. The study revealed that there are both similarities and a number of differences in peat group chemical composition. All samples showed the low ash-content (up to 3.5%) and the content of easily-hydrolyzable components is inversely proportional to the degree of peat decomposition. This is due to their greater bioavailability compared to other organic matter components. Despite the similar values of the bitumen content in the peat samples (3.5-4.2%), the composition and content of HS differ significantly: 26% and 13-15% for the peat samples from the Siberian region and the Belomor-Kuloy plateau respectively. The ratio of humic and fulvic acids in the peat samples are 3.8 and 1.8 that is consistent with differences in the degree of decomposition.</p><p>Humic substances macromolecules are diphilic, so they can show surface activity in solutions. By the Wilhelmy method it was found that for the adsorption of humic substances into the surface layer to an equilibrium state is required 16-20 hours. While the greatest changes (by 65-85%) occur during the first 30-60 minutes. The maximum depression of surface tension was 31.5-35.8 mN/m. This is characteristic of compounds with high molecular weight. The presence of bitumen components, which also have surface activity, in the HS solution, accelerates the achievement of adsorption equilibrium at the air–water interface.</p><p>Based on the measuring of the surface tension the surface activity was determined. The surface activity characterizes the process of the surface layer formation of a surfactant solution at the air–water interface with an infinite dilution. This parameter was calculated depending on HS solution concentration. The surface activity value of HS solutions extracted from Siberian peat is 2 2.1 N/ m*g that is 2 times higher than the HS solutions from the Belomor-Kuloy plateau. Removal of bitumens from the peat leads to an increase of the surface activity of HS solution from Siberian peat at twice it was before, but for Belomor-Kuloy plateau peat it decreases by 10%. The observed differences can be associated with the peculiarities of the composition of the bitumen. This trend has been confirmed by calculation of the critical micelle concentration and the measurement of the hydrodynamic sizes of particles in solutions using the dynamic light-scattering method.</p><p>It was revealed high surface activity of HS solution. So the range of their possible use could be extended (synthetic detergents, emulsifiers, etc.).</p><p>The reported study was funded by RFBR according to the research projects № 20-35-90037, 18-05-60151, and 18-05-70087.</p>

The Role of Aluminium Source (Al2O3/AlN) in the Synthesis of the Ca-α-SiAlON:Eu2+ Phosphor

2016 ◽  
Vol 697 ◽  
pp. 311-317
Author(s):  
Tomasz Pawlik ◽  
Daniel Michalik ◽  
Małgorzata Sopicka-Lizer ◽  
Aleksandra Miczek ◽  
Paweł Krzywda ◽  
...  
Keyword(s):  
Solid Solution ◽  
Chemical Composition ◽  
Solid State ◽  
Solid State Reaction ◽  
Emission Intensity ◽  
Carbon Addition ◽  
Photoluminescence Properties ◽  
Phosphor Powder ◽  
Rich Liquid

The purpose of the presented research was to compare the effect of changing the aluminium source in the mixture of initial powders on the properties of the final phosphor powder of Ca – α-SiAlON doped with Eu2+. The phosphor composition was designed as Eu0,048Ca0,752Si9,6Al2,4O0,8N15,2 and it was prepared by the solid state reaction in a temperature range of 1450-1650 °C. AlN and/or η-Al2O3 powders were used as a source of aluminium. It has been found that presence of aluminium nitride or oxide in the mixture of initial materials significantly changed the course of α-sialon formation, chemical composition of that solid solution and the resultant photoluminescence properties. It has been established that a small amount of η-Al2O3 with a suitable carbon addition was profitable for liquid formation and enhanced crystallization of Ca,Eu-α-sialon. The excessive oxide-rich liquid at reaction temperature led to sintering of phosphor particles and decreased emission intensity while lack of sufficient amount of liquid (nitrogen-rich starting composition) resulted in AlN presence and considerably reduced emission intensity of this phosphor.

scholarly journals Discovery of Surfactant-Like Peptides from a Phage-Displayed Peptide Library

Viruses ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 1442
Author(s):  
Toshiki Sawada ◽  
Rina Oyama ◽  
Michihiro Tanaka ◽  
Takeshi Serizawa
Keyword(s):  
Surface Tension ◽  
Surface Activity ◽  
Materials Science ◽  
Peptide Library ◽  
Phage Clone ◽  
Amino Acid Sequences ◽  
Materials Science And Engineering ◽  
Functional Peptides ◽  
Phage Displayed Peptide Library

Peptides with specific affinities for various materials have been identified in the past three decades and utilized in materials science and engineering. A peptide’s capability to specifically interact with materials is not naturally derived but screened from a biologically constructed peptide library displayed on phages or cells. To date, due to limitations in the screening procedure, the function of screened peptides has been primarily limited to the affinity for target materials. Herein, we demonstrated the screening of surfactant-like peptides from a phage-displayed peptide library. A screened phage clone displaying a peptide showed high activity for accumulating at emulsion surfaces with certain assembled structures, resulting in stable emulsions. The surface tension for the solution of the chemically synthesized peptide decreased with increasing peptide concentration, demonstrating certain surface activity, which corresponded to the ability to decrease the surface tension of liquids (e.g., water), owing to the accumulation of molecules at the air–liquid or liquid–liquid interface. Peptides with a randomized sequence did not lower the surface tension, indicating the essential role of amino acid sequences in surface activity. Our strategy for identifying novel functional peptides from a phage-displayed peptide library can be used to expand the applicability of peptidyl materials and biosurfactants.

The role of lipids and polysaccharides in model root mucilage with implications for the surface activity of the rhizosphere

Biologia ◽  
2017 ◽  
Vol 72 (11) ◽  
Author(s):  
Fengxian Chen ◽  
Gilboa Arye
Keyword(s):  
Surface Tension ◽  
Surface Activity ◽  
Polygalacturonic Acid ◽  
Root Mucilage ◽  
Solid Phases ◽  
Liquid And Solid Phases

AbstractThe main goal of this study was to evaluate the role of polysaccharide and phospholipids on the surface activity of model root mucilage in its liquid and solid phases. Polygalacturonic acid (PGA) and Phosphatidylcholine (PC) were used as representative polysaccharide and phospholipid, respectively. The surfactant performance of the PC found to be superior relative to the PGA – reducing the surface tension (ST) down to 32.9 mN m

scholarly journals Cloud condensation nuclei activity of six pollenkitts and the influence of their surface activity

2019 ◽  
Vol 19 (7) ◽  
pp. 4741-4761 ◽  
Author(s):  
Nønne L. Prisle ◽  
Jack J. Lin ◽  
Sara Purdue ◽  
Haisheng Lin ◽  
J. Carson Meredith ◽  
...  
Keyword(s):  
Surface Tension ◽  
Surface Activity ◽  
Water Uptake ◽  
Cloud Condensation Nuclei ◽  
Cloud Droplet ◽  
Cloud Microphysics ◽  
Surface Partitioning ◽  
Aqueous Surface ◽  
Droplet Activation

Abstract. The role of surfactants in governing water interactions of atmospheric aerosols has been a recurring topic in cloud microphysics for more than two decades. Studies of detailed surface thermodynamics are limited by the availability of aerosol samples for experimental analysis and incomplete validation of various proposed Köhler model frameworks for complex mixtures representative of atmospheric aerosol. Pollenkitt is a viscous material that coats grains of pollen and plays important roles in pollen dispersion and plant reproduction. Previous work suggests that it may also be an important contributor to pollen water uptake and cloud condensation nuclei (CCN) activity. The chemical composition of pollenkitt varies between species but has been found to comprise complex organic mixtures including oxygenated, lipid, and aliphatic functionalities. This mix of functionalities suggests that pollenkitt may display aqueous surface activity, which could significantly impact pollen interactions with atmospheric water. Here, we study the surface activity of pollenkitt from six different species and its influence on pollenkitt hygroscopicity. We measure cloud droplet activation and concentration-dependent surface tension of pollenkitt and its mixtures with ammonium sulfate salt. Experiments are compared to predictions from several thermodynamic models, taking aqueous surface tension reduction and surfactant surface partitioning into account in various ways. We find a clear reduction of surface tension by pollenkitt in aqueous solution and evidence for impact of both surface tension and surface partitioning mechanisms on cloud droplet activation potential and hygroscopicity of pollenkitt particles. In addition, we find indications of complex nonideal solution effects in a systematic and consistent dependency of pollenkitt hygroscopicity on particle size. The impact of pollenkitt surface activity on cloud microphysics is different from what is observed in previous work for simple atmospheric surfactants and more resembles recent observations for complex primary and secondary organic aerosol, adding new insight to our understanding of the multifaceted role of surfactants in governing aerosol–water interactions. We illustrate how the explicit characterization of pollenkitt contributions provides the basis for modeling water uptake and cloud formation of pollen and their fragments over a wide range of atmospheric conditions.

SOME ASPECTS OF THE FUNCTION OF FSH- AND LH-LIKE HORMONES IN NORMAL AND HYPOPHYSECTOMIZED FEMALE RATS, IN CONNECTION WITH RESERPINE ADMINISTRATION

1965 ◽  
Vol 49 (1) ◽  
pp. 28-38
Author(s):  
M. Grönroos ◽  
E. Mäkinen ◽  
K. Lahtinen ◽  
R. Tirri
Keyword(s):  
Mechanism Of Action ◽  
Biological Effect ◽  
Female Rats ◽  
Histological Picture ◽  
Peripheral Effect ◽  
Pituitary Secretion

ABSTRACT The effect of reserpine on the secretion of FSH and LH was studied as well as the role of the peripheral effect of reserpine after hypophysectomy. The results in the unoperated animals suggest that reserpine inhibits the pituitary secretion of both FSH and LH. Both these hormones combined with reserpine had a very different biological effect than was seen without reserpine. HCG (LH-like) and particularly PMS (FSH-like) hormones combined with reserpine caused definite enlargement of the ovaries. In the hypophysectomized groups, the effect of the PMS and HCG hormones administered together with reserpine or without it was the same with regard to the weight of the ovaries, but not with regard to their histological picture. On the basis of these results, reserpine may be said to have a peripheral effect although the nature of its mechanism of action is difficult to state. Reserpine probably affects the ovaries by inhibiting the follicular cycle and, consequently, the formation of new and more mature follicles.

Sign in / Sign up

Export Citation Format

Share Document