scholarly journals Mg,Sr-Cosubstituted Hydroxyapatite with Improved Structural Properties

2021 ◽  
Vol 11 (11) ◽  
pp. 4930
Author(s):  
Elena Landi ◽  
Stefano Guizzardi ◽  
Elettra Papa ◽  
Carlo Galli
Keyword(s):  
Bone Structure ◽  
Exchange Process ◽  
Bone Matrix ◽  
Molar Ratio ◽  
Thermal Treatments ◽  
Native Bone ◽  
Ion Exchange Process ◽  
Wide Range ◽  
Bone Substitute Materials ◽  
Substitute Materials

Bone substitute materials require specific properties to make them suitable for implantation, such as biocompatibility and resistance to mechanical loads. Mg,Sr-cosubstituted hydroxyapatite (MgSr-HA) is a promising bone scaffold candidate because its structure is similar to the native bone matrix. However, MgSr-HA materials do not typically withstand thermal treatments over 800 °C, because Mg promotes HA degradation to less stable tricalcium phosphate, a compound that, albeit biocompatible, is not found in bone. We, therefore, designed an ion-exchange process to enrich sintered Sr-HA with Mg and obtain MgSr-HA porous constructs. These materials contained a 0.04–0.08 Mg/Ca molar ratio and a 0.12–0.13 Sr/Ca molar ratio, and had up to 20 MPa of compressive strength, suitable for use as bone fillers or scaffolds. Unlike previous synthetic Mg,Sr-substituted apatite powders, the proposed process did not degrade HA and thus preserved its similarity to bone structure. The obtained material thus combines the presence of bioactive Mg and Sr ions in the HA lattice with a 3D morphological/structural organization that can be customized in pore size and distribution, as well as in mechanical strength, thus potentially covering a wide range of clinical applications.

Zinc Loaded Clay as Activator in Sulfur Vulcanization: A New Route for Zinc Oxide Reduction in Rubber Compounds

2004 ◽  
Vol 77 (2) ◽  
pp. 336-355 ◽  
Author(s):  
Geert Heideman ◽  
Jacques W. M. Noordermeer ◽  
Rabin N. Datta ◽  
Ben van Baarle
Keyword(s):  
Model Compound ◽  
Exchange Process ◽  
Zinc Level ◽  
Zinc Compounds ◽  
Ion Exchange Process ◽  
Rubber Compounds ◽  
Wide Range ◽  
Sulfur Vulcanization ◽  
Reduction Of Zno ◽  
Insight Into

Abstract Concern about the release of eco-toxic zinc species from rubbers into the environment leads to an increasing interest in potential substitutes. Although alternative metal oxides and zinc compounds as activators for sulfur vulcanization have been studied thoroughly, at present no viable alternative has been found to eliminate ZnO completely from rubber compounds, without significantly jeopardizing processing as well as performance characteristics. In this paper, the application of a new activator for sulfur vulcanization will be discussed. This activator is developed based on the assumption that an increase in the availability of Zn2+-ions could lead to a considerable reduction of ZnO in rubber compounds. Montmorillonite clay was used as carrier material and loaded with Zn2+-ions via an ion-exchange process. Application in a wide range of natural and synthetic rubbers has been explored. Results clearly demonstrate that this Zn-Clay can substitute conventional ZnO, retaining the curing and physical properties of the rubber products but reducing the zinc concentration with a factor 10 to 20. Model Compound Vulcanization studies have been used to gain an insight into the mechanism of this activator. It can be concluded that systems with Zn2+-ions on a support represent a new and novel route to reduce the zinc level, and therefore to minimize its environmental impact significantly.

Effect of Octacalcium Phosphate-Based Bone Substitute Materials on Oriented Bone Regeneration

2017 ◽  
Vol 758 ◽  
pp. 223-227
Author(s):  
Osamu Suzuki ◽  
Takahisa Anada
Keyword(s):  
Bone Matrix ◽  
Octacalcium Phosphate ◽  
Tissue Response ◽  
Gelatin Sponge ◽  
Natural Polymers ◽  
Preparation Conditions ◽  
Biological Responses ◽  
Bone Substitute Materials ◽  
Collagen Molecules ◽  
Substitute Materials

The characteristics and the biological responses of octacalcium phosphate (OCP) crystals, obtained in the presence of natural polymers, were summarized based on our studies reported. OCP obtained with collagen molecules in the solution had a plate-like morphology while OCP obtained with gelatin molecules in the solution exhibited elongated morphology toward long axis of the crystals. Oriented bone matrix formation was observed by the OCP inclusion in gelatin sponge in a critical-sized rat calvaria defect within the implantation periods around 8 weeks. It seems likely that specific crystal property of OCP obtained in distinct preparation conditions may affect bone tissue response probably through the modulation of OCP crystal characteristics.

Pressure induced photoluminescence modulation in a wide range and synthesis of monodispersed ternary AgCuS nanocrystal based on Ag2S nanocrystals

Nanoscale ◽  
2018 ◽  
Vol 10 (5) ◽  
pp. 2577-2587 ◽  
Author(s):  
Yingnan Wang ◽  
Xiaoteng Li ◽  
Manzhang Xu ◽  
Kai Wang ◽  
Hongyang Zhu ◽  
...  
Keyword(s):  
High Pressure ◽  
Ion Exchange ◽  
Wavelength Range ◽  
Exchange Process ◽  
Ion Exchange Process ◽  
Wide Range ◽  
Large Wavelength

Based on Ag2S NCs, we have modulated their PL in a large wavelength range via a high pressure approach and synthesized size tunable β-AgCuS NCs via an ion exchange process.

scholarly journals Purification and characterization of glycerin obtained from soybean biodiesel production

2019 ◽  
Vol 10 (3) ◽  
pp. 252-262
Author(s):  
Roberto Guimarães Pereira ◽  
Fernanda Arenásio Benites Alves de Souza
Keyword(s):  
Activated Carbon ◽  
Ion Exchange ◽  
Exchange Process ◽  
Biodiesel Production ◽  
Biofuel Production ◽  
Crude Glycerin ◽  
Purification Process ◽  
Ion Exchange Process ◽  
Wide Range ◽  
Soybean Biodiesel

The crude glycerin is a raw material which can be applied in a wide range of products, even with all its impurities, without the need for purification. However, the purification processes allow a wider application, making it more salable. With increasing demand for biodiesel, a glycerin excess is being released to the market. Therefore, the search for alternative treatments for the glycerin derived from the biodiesel production process is of utmost importance, ensuring biofuel production flow. This paper presents glycerin purification experiments done in a crude glycerin (64.44% of glycerol) obtained from the soybean biodiesel production, which was subjected to pre-purification process, purification with activated carbon and by ion exchange process. After the purification process the glycerin sample was characterized and compared with commercially used glycerin. The highest content of glycerol achieved was 94.22% corresponding to the steps of: pre-purification process (washing, acidification, separation, neutralization, salting-outing and evaporation); purification with activated carbon and by ion exchange process with mixed resin.   

Calcium Phosphate Bone Cement (CPBC): Development, Commercialization and Future Challenges

2011 ◽  
Vol 493-494 ◽  
pp. 349-354 ◽  
Author(s):  
Aliassghar Tofighi
Keyword(s):  
Chemical Composition ◽  
Bone Substitute ◽  
Mechanical Performance ◽  
Demineralized Bone Matrix ◽  
Bone Matrix ◽  
User Friendliness ◽  
Carbonated Apatite ◽  
Calcium Phosphate Bone Cement ◽  
Bone Substitute Materials ◽  
Substitute Materials

The first generation of synthetic bone substitute materials, hydroxyapatite (or HA), was initially investigated as a “non self-hardening” biomaterial for remodeling of bone defects. CPBCs concepts were used as a platform to initiate a second generation of injectable, self-hardening cement. The variety of CPBC’s chemical composition leads to a better understanding of their mechanism of reaction and their proposed classification: acid-base, mono-component and hydrolysable. After hydration, mixing, and full chemical reaction, these cements have the ability to precipitate different end products (e.g. HA, calcium deficient apatite, carbonated apatite, brushite, etc.). In fact, the initial idea of having higher mechanical performance (>50 MPa in compression) for a bone void filler application was abandoned and has led to a greater focus on cement fast-hardening (<15 min), higher total porosity (>60%), extended performance of injectability (8 to 22 G), fast resorbability (< 2 years) and user-friendliness for the clinicians. A new CPBC combination (cement plus additives) has particularly improved rheological and biointegrity performance. A hybrid of CPBC-DBM (Demineralized Bone Matrix) has also added an osteoinductivity performance to the initial osteoconductive CPBC.This paper will propose a comparison of the chemical composition, reaction, and performance characteristics of major commercially available CPBC products. Furthermore, it will describe today’s surgeon’s CPBC needs as bone substitute materials for different clinical applications. Finally, we will discuss what we learned so far, how we can resolve several clinical impacts & product recall, and how we believe CPBC designers can meet development challenges, and users’ specific requirements.

scholarly journals Cation Exchange Capacity of Zeolite X from Bagasse Ash against Magnesium(II)

ALCHEMY ◽  
2016 ◽  
Vol 4 (2) ◽  
pp. 107
Author(s):  
Suci Amalia
Keyword(s):  
Cation Exchange ◽  
Cation Exchange Capacity ◽  
Human Life ◽  
Exchange Process ◽  
Water Hardness ◽  
Exchange Capacity ◽  
Molar Ratio ◽  
Zeolite X ◽  
Edta Titration ◽  
Ion Exchange Process

<p class="BodyAbstract">Water is a substance crucial for human life and industries. The good water must be fulfill some criteria, such as absence of Ca<sup>2+</sup> or Mg<sup>2+</sup> cations. The cations can be reduced by ion exchange process. This study used synthesized zeolite X from bagasse ash as cation exchange for Mg<sup>2+</sup>. Mg ion was used as standard to determine hardness of water by EDTA titration. The analysis showed cation exchange capacity of zeolite X with molar ratio of  Si/Al 1; 1,5 and 2 was 1,9. The value indicated zeolite X have high capability as cation absorbents for Mg<sup>2+</sup> ion.</p><p class="BodyAbstract"> </p><strong><em>Keywords:</em></strong><em> bagasse ash, cation exchange capacity, magnesium(II), water hardness, zeolite X</em>

Bone Substitute Materials in Modern Dentistry

2017 ◽  
Vol 1 (4) ◽  
Author(s):  
Andrius Geguzis ◽  
Inesa Astramskaite ◽  
Dovile Gabseviciute
Keyword(s):  
Bone Substitute ◽  
Bone Substitute Materials ◽  
Substitute Materials

Removal of Toxic Dyestuffs from Aqueous Solution by Amphoteric Bioadsorbent

2020 ◽  
Vol 16 ◽  
Author(s):  
Reda M. El-Shishtawy ◽  
Abdullah M. Asiri ◽  
Nahed S. E. Ahmed
Keyword(s):  
Aqueous Solution ◽  
Ion Exchange ◽  
Dye Removal ◽  
Exchange Process ◽  
Cationic Dyes ◽  
Carboxyl Groups ◽  
Maximum Adsorption Capacity ◽  
Equilibrium Isotherm ◽  
Ion Exchange Process ◽  
Dyes And Pigments

Background: Color effluents generated from the production industry of dyes and pigments and their use in different applications such as textile, paper, leather tanning, and food industries, are high in color and contaminants that damage the aquatic life. It is estimated that about 105 of various commercial dyes and pigments amounted to 7×105 tons are produced annually worldwide. Ultimately, about 10–15% is wasted into the effluents of the textile industry. Chitin is abundant in nature, and it is a linear biopolymer containing acetamido and hydroxyl groups amenable to render it atmospheric by introducing amino and carboxyl groups, hence able to remove different classes of toxic organic dyes from colored effluents. Methods: Chitin was chemically modified to render it amphoteric via the introduction of carboxyl and amino groups. The amphoteric chitin has been fully characterized by FTIR, TGA-DTG, elemental analysis, SEM, and point of zero charge. Adsorption optimization for both anionic and cationic dyes was made by batch adsorption method, and the conditions obtained were used for studying the kinetics and thermodynamics of adsorption. Results: The results of dye removal proved that the adsorbent was proven effective in removing both anionic and cationic dyes (Acid Red 1 and methylene blue (MB)), at their respective optimum pHs (2 for acid and 8 for cationic dye). The equilibrium isotherm at room temperature fitted the Freundlich model for MB, and the maximum adsorption capacity was 98.2 mg/g using 50 mg/l of MB, whereas the equilibrium isotherm fitted the Freundlich and Langmuir model for AR1 and the maximum adsorption capacity was 128.2 mg/g. Kinetic results indicate that the adsorption is a two-step diffusion process for both dyes as indicated by the values of the initial adsorption factor (Ri) and follows the pseudo-second-order kinetics. Also, thermodynamic calculations suggest that the adsorption of AR1 on the amphoteric chitin is an endothermic process from 294 to 303 K. The result indicated that the mechanism of adsorption is chemisorption via an ion-exchange process. Also, recycling of the adsorbent was easy, and its reuse for dye removal was effective. Conclusion: New amphoteric chitin has been successfully synthesized and characterized. This resin material, which contains amino and carboxyl groups, is novel as such chemical modification of chitin hasn’t been reported. The amphoteric chitin has proven effective in decolorizing aqueous solution from anionic and cationic dyes. The adsorption behavior of amphoteric chitin is believed to follow chemical adsorption with an ion-exchange process. The recycling process for few cycles indicated that the loaded adsorbent could be regenerated by simple treatment and retested for removing anionic and cationic dyes without any loss in the adsorbability. Therefore, the study introduces a new and easy approach for the development of amphoteric adsorbent for application in the removal of different dyes from aqueous solutions.

In vitro effects of particulate bone substitute materials on the resorption activity of human osteoclasts

2017 ◽  
Vol 34 ◽  
pp. 291-306 ◽  
Author(s):  
G Russmueller ◽  
◽  
L Winkler ◽  
R Lieber ◽  
R Seemann ◽  
...  
Keyword(s):  
Bone Substitute ◽  
Bone Substitute Materials ◽  
In Vitro Effects ◽  
Substitute Materials ◽  
Human Osteoclasts
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