scholarly journals Surfactin as a Green Agent Controlling the Growth of Porous Calcite Microstructures

2020 ◽  
Vol 21 (15) ◽  
pp. 5526
Author(s):  
Anna Bastrzyk ◽  
Marta Fiedot-Toboła ◽  
Halina Maniak ◽  
Izabela Polowczyk ◽  
Grażyna Płaza
Keyword(s):  
Crystal Growth ◽  
Calcium Carbonate ◽  
Crystal Surface ◽  
Free Calcium ◽  
Scanning Calorimetry ◽  
Green Method ◽  
Synthesis Time ◽  
Carbonate Formation ◽  
Surface Active

This study presents a new, simple way to obtain mesoporous calcite structures via a green method using an eco-friendly surface-active compound, surfactin, as a controlling agent. The effects of synthesis time and surfactin concentration were investigated. The obtained structures were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) coupled with gas mass spectrometry (QMS) analysis. The experimental data showed that surfactin molecules significantly changed the morphology of the calcite crystals, roughening and deforming the surface and creating a greater specific surface area, even at low biosurfactant concentrations (10 ppm). The size of the crystals was reduced, and the zeta potential value of calcium carbonate was more negative when more biosurfactant was added. The XRD data revealed that the biomolecules were incorporated into the crystals and slowed the transformation of vaterite into calcite. It has been shown that as long as vaterite is present in the medium, the calcite surface will be less deformed. The strong influence of surfactin molecules on the crystal growth of calcium carbonate was due to the interaction of surfactin molecules with free calcium ions in the solution as well as the biomolecules adsorption at the formed crystal surface. The role of micelles in crystal growth was examined, and the mechanism of mesoporous calcium carbonate formation was presented.

scholarly journals Effects of Fluoride on the Interactions between Amelogenin and Apatite Crystals

2008 ◽  
Vol 87 (1) ◽  
pp. 39-44 ◽  
Author(s):  
K. Tanimoto ◽  
T. Le ◽  
L. Zhu ◽  
J. Chen ◽  
J.D.B. Featherstone ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Crystal Surface ◽  
Titration Calorimetry ◽  
Carbonated Hydroxyapatite ◽  
Protein Assay ◽  
Binding Rate ◽  
Apatite Crystals ◽  
Sds Page ◽  
Initial Binding

Fluorosed enamel is more porous and less mineralized, possibly related to altered amelogenin-modulated crystal growth. The purpose of this study was to examine the role of fluoride in interactions between amelogenin and apatite crystals. Recombinant human amelogenin (rh174) was bound to carbonated hydroxyapatite containing various amounts of fluoride, and analyzed by protein assay, SDS PAGE, and AFM. Interactions between rh174 and fluoride were assayed by isothermal titration calorimetry (ITC). The initial binding rate of rh174, as well as total amount of rh174 bound to fluoride-containing carbonated hydroxyapatite, was greater than that in the control carbonated hydroxyapatite. Fluoride in solution at physiologic (5.3 micromolar, or 0.1 ppm) concentrations showed no significant effect on binding, but higher fluoride levels significantly decreased protein binding. ITC showed no interactions between fluoride and rh174. These results suggest that fluoride incorporation into the crystal lattice alters the crystal surface to enhance amelogenin binding, with no direct interactions between fluoride and amelogenin.

scholarly journals The role of phosphorylation and dephosphorylation of shell matrix proteins in shell formation: an in vivo and in vitro study

CrystEngComm ◽  
2018 ◽  
Vol 20 (27) ◽  
pp. 3905-3916 ◽  
Author(s):  
Jinzhe Du ◽  
Guangrui Xu ◽  
Chuang Liu ◽  
Rongqing Zhang
Keyword(s):  
Calcium Carbonate ◽  
In Vitro Study ◽  
Matrix Proteins ◽  
Shell Formation ◽  
Carbonate Formation ◽  
Shell Matrix ◽  
Shell Matrix Proteins

Phosphorylation of shell matrix proteins is critical for shell formation in vivo and can modulate calcium carbonate formation in vitro.

Механизмдействияингибиторовприобразованииосадкакарбонатакальциявобратноосмотическихаппаратах

2019 ◽  
pp. 10-22
Author(s):  
A. Pervov ◽  
A. Andrianov
Keyword(s):  
Calcium Carbonate ◽  
Reverse Osmosis ◽  
Experimental Technique ◽  
Crystallization Process ◽  
Crystal Surface ◽  
Membrane Surface ◽  
Crystal Nucleation ◽  
Phase Crystal ◽  
Crystalline Growth

Знание механизма образования осадков малорастворимых солей на обратноосмотических мембранах чрезвычайно важно при выборе мероприятий по их предотвращению и сокращению расхода концентрата. Проведенные исследования позволили сформулировать новый взгляд на механизм образования кристаллических отложений и роль ингибиторов в предотвращении этого процесса. В основе разработки экспериментальной методики лежит представление о том, что первая фаза кристаллизации зародышеобразование является гомогенной, т. е. происходит в застойных зонах в объеме концентрата при высоких значениях пересыщения по карбонату кальция. После образования кристаллы выносятся из застойных зон и осаждаются на поверхности мембраны, как и другие взвешенные частицы, содержащиеся в обрабатываемой воде. Представлены результаты изучения процесса адсорбции молекул полимерных ингибиторов на поверхности кристаллов при зародышеобразовании и кристаллическом росте на мембране. Приведены экспериментально полученные зависимости скорости адсорбции ингибиторов от их дозы, скорости образования карбоната кальция, скорости зародышеобразования от общей поверхности зародышевых кристаллов. Изучение микрофотографий показало зависимость размера и количества кристаллов от значения пересыщения в застойной зоне при зародышеобразовании, а также от эффективности ингибитора. Представлена методика, позволяющая определить концентрации растворенных солей в застойных зонах мембранного аппарата и значения пересыщения, соответствующие началу процесса кристаллизации, без добавления различных ингибиторов и с их использованием.Knowledge of the mechanism of precipitation of slightlysoluble salts on reverse osmosis membranes is extremely important while choosing measures to prevent it and reduce the consumption of concentrate. The conducted studies provided for enunciating a fresh approach to the mechanism of crystalline deposit formation and the role of inhibitors in preventing this process. The development of the experimental technique is based on the idea that the first crystallization phase crystal nucleation is homogeneous, that is, occurs in stagnant zones in the concentrate volume at high oversaturation with calcium carbonate. Upon the formation the crystals are removed from the stagnant zones and settled on the membrane surface like other suspended particles present in the treated water. The results of studying the adsorption of polymer inhibitor molecules on the crystal surface during nucleation and crystalline growth on the membrane are presented. The experimentally obtained dependences of the rate of adsorption of inhibitors on the dose of inhibitors, the rate of formation of calcium carbonate, the rate of nucleation, and on the total surface of the germinal crystals are given. The study of micrographs of crystals showed the dependence of the size and number of crystals on the oversaturation value in the stagnant zone during nucleation as well as on the effectiveness of the inhibitor. A method is presented that allows determining the concentration of dissolved salts in the stagnant zones of the membrane apparatus and the oversaturation values corresponding to the onset of the crystallization process eliminating the addition and use of various inhibitors.

The Inhibition of Calcium Carbonate Formation in Aqueous Supersaturated Solutions, Spontaneous Precipitation and Seeded Crystal Growth

2005 ◽  
pp. 123-137 ◽  
Author(s):  
Pavlos G. Klepetsanis ◽  
Angeliki Kladi ◽  
Terje Ostvold ◽  
Christos G. Kontoyiannis ◽  
Petros G. Koutsoukos ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Calcium Carbonate ◽  
Carbonate Formation ◽  
Supersaturated Solutions

scholarly journals Uncovering the Role of Bicarbonate in Calcium Carbonate Formation at Near‐Neutral pH

2021 ◽  
Author(s):  
Yu-Chieh Huang ◽  
Ashit Rao ◽  
Shing-Jong Huang ◽  
Chun-Yu Chang ◽  
Markus Drechsler ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Neutral Ph ◽  
Carbonate Formation

scholarly journals Self-preservation strategies during bacterial biomineralization with reference to hydrozincite and implications for fossilization of bacteria

2014 ◽  
Vol 11 (100) ◽  
pp. 20140845 ◽  
Author(s):  
Bryne T. Ngwenya ◽  
Marisa Magennis ◽  
Francesca Podda ◽  
Andrei Gromov
Keyword(s):  
Crystal Growth ◽  
Calcium Carbonate ◽  
Laboratory Experiments ◽  
Extracellular Polymeric Substances ◽  
High Porosity ◽  
Effective Mechanism ◽  
Metabolite Exchange ◽  
Open Question ◽  
Sphere Formation

The induction of mineralization by microbes has been widely demonstrated but whether induced biomineralization leads to distinct morphologies indicative of microbial involvement remains an open question. For calcium carbonate, evidence suggests that microbial induction enhances sphere formation, but the mechanisms involved and the role of microbial surfaces are unknown. Here, we describe hydrozincite biominerals from Sardinia, Italy, which apparently start life as smooth globules on cyanobacterial filaments, and evolve to spheroidal aggregates consisting of nanoplates. Complementary laboratory experiments suggest that organic compounds are critical to produce this morphology, possibly by inducing aggregation of nanoscopic crystals or nucleation within organic globules produced by metabolizing cells. These observations suggest that production of extracellular polymeric substances by microbes may constitute an effective mechanism to enhance formation of porous spheroids that minimize cell entombment while also maintaining metabolite exchange. However, the high porosity arising from aggregation-based crystal growth probably facilitates rapid oxidation of entombed cells, reducing their potential to be fossilized.

scholarly journals Uncovering the Role of Bicarbonate in Calcium Carbonate Formation at Near‐Neutral pH

2021 ◽  
Author(s):  
Yu-Chieh Huang ◽  
Ashit Rao ◽  
Shing-Jong Huang ◽  
Chun-Yu Chang ◽  
Markus Drechsler ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Neutral Ph ◽  
Carbonate Formation

scholarly journals Investigation of antiscalant dosing influence on scaling process in reverse osmosis facilities and membrane surface adsorption

Vestnik MGSU ◽  
2019 ◽  
pp. 722-733 ◽  
Author(s):  
Val S. Frenkel ◽  
Alexey G. Pervov ◽  
Alexey P. Andrianov ◽  
Vladimir A. Golovesov
Keyword(s):  
Crystal Growth ◽  
Calcium Carbonate ◽  
Reverse Osmosis ◽  
Growth Mechanism ◽  
Calcium Ions ◽  
Natural Water ◽  
Crystal Surface ◽  
Membrane Surface ◽  
Membrane Surfaces ◽  
Crystal Growth Mechanism

Introduction. Understanding of crystal growth mechanism enables to develop efficient tools to control scaling and improve the process of treatment using membranes and increasing the amount of filtrate output. This investigation is aimed at studying an antiscalant behaviour in reverse osmosis (RO) process when treating ground water. Experimental dependences of calcium carbonate scaling efficiency on antiscalant dosage were found. Rates of adsorption on crystal surface of scaling deposit and on membrane surfaces were compared. Dependences of rates of inhibitor adsorption on crystal surface versus scaling rates were determined. Inhibitor adsorption on RO membrane surfaces was studied. New approaches to studying crystal growth mechanism in the presence of polymeric inhibitors are presented. Materials and methods. In the course of experiments conducted with using inhibitor dissolved in distilled water, inhibitor sorption on membrane surface was observed in the absence of calcium ions. As to experiments with dosing the inhibitor in tap water, the inhibitor sorption on the membrane did not occur: the inhibitor was adsorbed on the surface of the scaling crystals. Results. Experimental relationships are obtained that show dependencies of calcium carbonate deposit growth rates versus RO facility filtrate output values in the presence of different antiscalants with their dose values of 3, 5 and 7 mg/l. The article shows that antiscalant dose value does not provide substantial influence on antiscalant efficiency when natural water with low hardness is treated in the RO facility. This permits substantial reduction of operational costs. It was also proved that inhibitor is not adsorbed on membrane surface during natural water treatment that also confirms efficiency of low antiscalant dosing. Conclusions. Low hardness values of natural water (3–5 mill equivalents per liter) demonstrate that antiscalant efficiencies do not depend on its dose. Rate of inhibitor adsorption on crystal surface during calcium carbonate deposition also increases with scaling rate increase. Rates of antiscalant consumption increase with antiscalant dose values. In natural water the dissolved antiscalant molecules are bonded with calcium ions therefore antiscalant does not react with membranes and is not adsorbed on membrane surface.

Mitochondrial matrix calcium ions regulate energy production in myocardium: A cytochemical study

1990 ◽  
Vol 48 (2) ◽  
pp. 166-167
Author(s):  
W.A. Jacob ◽  
R. Hertsens ◽  
A. Van Bogaert ◽  
M. De Smet
Keyword(s):  
Energy Metabolism ◽  
Calcium Ions ◽  
Energy Production ◽  
Regulation Of Respiration ◽  
Free Calcium ◽  
Mitochondrial Matrix ◽  
Cytochemical Study ◽  
Nmr Techniques

In the past most studies of the control of energy metabolism focus on the role of the phosphorylation potential ATP/ADP.Pi on the regulation of respiration. Studies using NMR techniques have demonstrated that the concentrations of these compounds for oxidation phosphorylation do not change appreciably throughout the cardiac cycle and during increases in cardiac work. Hence regulation of energy production by calcium ions, present in the mitochondrial matrix, has been the object of a number of recent studies.Three exclusively intramitochondnal dehydrogenases are key enzymes for the regulation of oxidative metabolism. They are activated by calcium ions in the low micromolar range. Since, however, earlier estimates of the intramitochondnal calcium, based on equilibrium thermodynamic considerations, were in the millimolar range, a physiological correlation was not evident. The introduction of calcium-sensitive probes fura-2 and indo-1 made monitoring of free calcium during changing energy metabolism possible. These studies were performed on isolated mitochondria and extrapolation to the in vivo situation is more or less speculative.

NON-DESTRUCTIVE EXPERIMENTS AND MODELING OF CALCIUM CARBONATE FORMATION IN SOILS

2020 ◽  
Author(s):  
Carolyn D. Bland ◽  
◽  
Timothy M. Gallagher ◽  
Daniel O. Breecker
Keyword(s):  
Calcium Carbonate ◽  
Carbonate Formation ◽  
Non Destructive
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