pH-Effect on Sinterability, Mechanical Properties and Cytotoxicity of Hydroxyapatite-Based Bone Grafts

2013 ◽  
Vol 319 ◽  
pp. 134-139
Author(s):  
Mehtap Demirel ◽  
Bunyamin Aksakal ◽  
Nese Basak
Keyword(s):  
Mechanical Properties ◽  
Ph Value ◽  
Ph Effect ◽  
Sol Gel ◽  
Bone Grafts ◽  
Quantitative Phase Analysis ◽  
Osteoblast Cells ◽  
Ph Values ◽  
Hardness Tests ◽  
Before And After

Hydroxyapatite (HA) based bone grafts were synthesized by sol-gel method at various pH values 5, 7, 9 and 12, respectively. In order to ascertain the influence of the obtained bone grafts on the morphology, sinterability and mechanical properties, each composition was sintered at 11500C, and quantitative phase analysis was characterized by XRD and FTIR. The microstructures were studied via SEM-EDX and the validation of mechanical properties was evaluated by compression and Vickers hardness tests. The density of HA synthesis samples with different pH values before and after sintering were measured. Besides, the cytotoxicity analysis were conducted for all grafts having various pH values. The experimental results revealed that the density and mechanical strenght of HA based bone grafts were increased with increasing pH value. The highest hardness and strength were obtained for the samples having pH=12. Furthermore, the samples with pH=12 exhibited the best densification and properties when compared to the samples at pH of 5, 7 and 9. The cytotoxicity tests also indicated that the pH=7-12 value showed no toxicity to osteoblast cells at 0,1 and 0,3 µM concentration, whereas HA synthesis sample at pH=5 value with 0,3 µM concentration induced significantly and reduced cell viability.

Influence of Alkali Treatment on Properties of Casein Grafted Acrylonitrile Fibers

2011 ◽  
Vol 233-235 ◽  
pp. 2532-2535
Author(s):  
Jing Gao
Keyword(s):  
Mechanical Properties ◽  
Ph Value ◽  
Alkali Treatment ◽  
Extrinsic Factors ◽  
Factors Affecting ◽  
Ph Values ◽  
Alkali Solutions ◽  
Finishing Process ◽  
Before And After ◽  
Intrinsic And Extrinsic Factors

Casein grafted acrylonitrile fibers were treated by different concentration alkali solutions. The fibers component were investigated using chemical analysis before and after alkali treatment. The effects of alkali pH value on homopolymer PAN, free casein, grafted casein and grafting degree of the fibers were discussed individually. At the same time, the mechanical properties of the fibers treated by alkali at various pH values were tested, and the intrinsic and extrinsic factors affecting fibers mechanical properties were analyzed. The results can play a certain reference role to the early manufacture and finishing process of casein grafted acrylonitrile fibers.

Effect of pH Value on the Synthesis of NiO Nanoparticles and Microstructure of NiO Based Composite Anode

2021 ◽  
Vol 317 ◽  
pp. 447-453
Author(s):  
Noor Hidayah Aniza Zakaria ◽  
Nafisah Osman
Keyword(s):  
Ph Value ◽  
Sol Gel ◽  
Secondary Phase ◽  
Average Diameter ◽  
Morphological Observation ◽  
Nio Nanoparticles ◽  
Composite Anode ◽  
Ph Values ◽  
Particle Size Analyzer ◽  
Nio Nps

NiO nanoparticle was synthesized by a sol-gel method with three different pH values namely pH=1, 7 and 11, and then calcined at temperature of 450 ᵒC. The influence of different pH values on the physical properties of NiO nanoparticles were investigated by a particle size analyzer (PSA), field emission scanning electron microscope (FESEM) and X-ray diffractometer (XRD). Structural analysis confirmed that a cubic structure of NiO nanoparticle was obtained without any secondary phase for NiO powders prepared with pH=1, while the peak of secondary phase (Ni) appeared for NiO powders prepared with pH= 7 and 11. Morphological observation showed that the NiO nanoparticles prepared with pH=7 and 11 tend to form more agglomerates compared to one prepared with pH=1. The average diameter of NiO nanoparticles with pH 1, 7 and 11 were approximately in the range of 19-26 nm, 21-28 nm, and 24-30 nm, respectively. NiO powder that was synthesized with pH=1 was further used to prepare composite anode of NiO Nps-BaCe0.54Zr0.36Y0.1O2.95 (BCZY) powder. Unfortunately a composite of NiO Nps-BaCeO3-BaZrO3 was obtained instead of BCZY and governed by agglomerates with size in the range of 70-300 nm.

Effect of pH Value on Structural and Optical Properties of Transparent Nano-Crystalline TiO2 Films Prepared by Sol-Gel Dip-Drive Coating

2013 ◽  
Vol 678 ◽  
pp. 80-85 ◽  
Author(s):  
Krishnasamy Sakthivel ◽  
T. Venkatachalam
Keyword(s):  
Ab Initio ◽  
Room Temperature ◽  
Ph Value ◽  
Sol Gel ◽  
Structural And Optical Properties ◽  
Glass Substrates ◽  
Ph Values ◽  
Nano Crystalline ◽  
Crystalline Nature ◽  
Deposited Films

Thin films of TiO2 have been deposited on well cleaned glass substrates by Sol-Gel dip-drive coating technique. The films have been prepared at three different pH values (1, 3.5 & 9) of Sol and annealed in muffle furnace at 550°C for one hour and are allowed to cool to room temperature. The films were characterized by XRD, EDAX, SEM and UV-Vis Spectrophotometer. The as deposited films were found to be amorphous in nature. The annealed films exhibit anatase in crystalline structure. The EDAX results have shown that all the films are maintained with TiO2 in composition. The XRD results reveal that they are nano-crystalline in nature and the crystalline nature increases with pH of the Sol. The transmittance and absorbance spectra have shown that the films are transparent and band gap of the films are of the order of 3.2eV. The ab initio studies of TiO2 (using GGA) was performed with Vienna ab initio Simulation package and the band structure and effective masses of the electrons and holes were determined.

scholarly journals Mechanical Behavior and Constitutive Model for Loess Samples under Simulated Acid Rain Conditions

2021 ◽  
Author(s):  
xia ye ◽  
Enlong Liu ◽  
Baofeng Di ◽  
yayang yu
Keyword(s):  
Mechanical Properties ◽  
Acid Rain ◽  
Mechanical Model ◽  
Ph Value ◽  
Simulated Acid Rain ◽  
Test Results ◽  
Hardening Model ◽  
Ph Values ◽  
Scanning Electron ◽  
Peak Value

Abstract In this paper, the sulfuric acid solution is diluted to pH 5.0, 4.0 and 3.0 to simulate the acid rain condition, and the triaxial compressional tests and scanning electron microscope are carried out to study the mechanical properties and evolution of the microstructure of the saturated loess samples. The results demonstrate that acid rain increases the porosity of loess samples, and the pore distribution is not uniform, so that the mechanical properties of loess samples change. With the decrease of pH value, the peak value of the deviatoric stress and the volumetric contraction of loess samples decreases, which causes the strength of soil to decrease. Furthermore, the framework of the chemical-mechanical model for loess under the action of acid rain is established, in which the loess is considered as porous medium material, and the variable of acid rain at different pH values through the degree of chemical reaction is taken into account in the double-hardening model, and the model is also verified by the triaxial test results finally.

scholarly journals Role of Charge Regulation and Fluctuations in the Conformational and Mechanical Properties of Weak Flexible Polyelectrolytes

2019 ◽  
Author(s):  
Pablo M. Blanco ◽  
Sergio Madurga ◽  
Claudio F. Narambuena ◽  
Francesc Mas ◽  
Josep L. Garcés
Keyword(s):  
Mechanical Properties ◽  
Electrostatic Interactions ◽  
Ph Value ◽  
Persistence Length ◽  
Excluded Volume ◽  
Average Charge ◽  
Zero Force ◽  
Charge Regulation ◽  
Ph Values

This work addresses the role of charge regulation (CR) and the associated fluctuations in the conformational and mechanical properties of weak polyelectrolytes. Due to CR, changes in the pH-value modifies the average macromolecular charge and conformational equilibria. A second effect is that, for a given average charge per site, fluctuations can alter the intensity of the interactions by means of correlation between binding sites. We investigate both effects by means of Monte Carlo simulations at constant pH-value, so that the charge is a fluctuating quantity. Once the average charge per site is available, we turn off the fluctuations by assigning the same average charge to every site. A constant charge MC simulation is then performed. We make use of a model which accounts for the main fundamental aspects of a linear flexible polyelectrolyte i.e. proton binding, angle internal rotation, bond stretching and bending. Steric excluded volume and differentiated treatment for short-range and long-range interactions are also included in the model. It can be regarded as a kind of "minimal'' model in the sense that contains a minimum number of parameters but still preserving the atomistic detail. It is shown that, if fluctuations are activated, gauche state bond probabilities increase, and the persistence length decreases, so that the polymer becomes more folded. Macromolecular stretching is also analyzed in presence of CR (the charge depends on the applied force) and without CR (the charge is fixed to the value at zero force). The analysis of the low force scaling behavior concludes that Pincus exponent becomes pH-dependent. Both with and without CR, a transition from 1/2 at high pH-values (phantom chain) to 3/5 to low pH-values (Pincus regime), is observed. Finally, the intermediate force stretching regime is investigated. It is found that CR induces a moderate influence in the force-extension curves and persistence length (which in this force regime becomes force-dependent). It is thus concluded that the effect of CR on the stretching curves is mainly due to changes in the average charge at zero force. It is also found that, for the cases studied, the effect of steric excluded volume is almost irrelevant compared to electrostatic interactions.

scholarly journals Role of Charge Regulation and Fluctuations in the Conformational and Mechanical Properties of Weak Flexible Polyelectrolytes

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1962 ◽  
Author(s):  
Pablo M. Blanco ◽  
Sergio Madurga ◽  
Claudio F. Narambuena ◽  
Francesc Mas ◽  
Josep L. Garcés
Keyword(s):  
Mechanical Properties ◽  
Electrostatic Interactions ◽  
Ph Value ◽  
Persistence Length ◽  
Excluded Volume ◽  
Average Charge ◽  
Zero Force ◽  
Charge Regulation ◽  
Ph Values

This work addresses the role of charge regulation (CR) and the associated fluctuations in the conformational and mechanical properties of weak polyelectrolytes. Due to CR, changes in the pH-value modifies the average macromolecular charge and conformational equilibria. A second effect is that, for a given average charge per site, fluctuations can alter the intensity of the interactions by means of correlation between binding sites. We investigate both effects by means of Monte Carlo simulations at constant pH-value, so that the charge is a fluctuating quantity. Once the average charge per site is available, we turn off the fluctuations by assigning the same average charge to every site. A constant charge MC simulation is then performed. We make use of a model which accounts for the main fundamental aspects of a linear flexible polyelectrolyte that is, proton binding, angle internal rotation, bond stretching and bending. Steric excluded volume and differentiated treatment for short-range and long-range interactions are also included. This model can be regarded as a kind of “minimal” in the sense that it contains a minimum number of parameters but still preserving the atomistic detail. It is shown that, if fluctuations are activated, gauche state bond probabilities increase and the persistence length decreases, so that the polymer becomes more folded. Macromolecular stretching is also analyzed in presence of CR (the charge depends on the applied force) and without CR (the charge is fixed to the value at zero force). The analysis of the low force scaling behavior concludes that Pincus exponent becomes pH-dependent. Both, with and without CR, a transition from 1/2 at high pH-values (phantom chain) to 3/5 at low pH-values (Pincus regime) is observed. Finally, the intermediate force stretching regime is investigated. It is found that CR induces a moderate influence in the force-extension curves and persistence length (which in this force regime becomes force-dependent). It is thus concluded that the effect of CR on the stretching curves is mainly due to the changes in the average charge at zero force. It is also found that, for the cases studied, the effect of steric excluded volume is almost irrelevant compared to electrostatic interactions.

Preservation of Archaeological Leather by Reinforcement with Styrene Butadiene Rubber

2014 ◽  
Vol 1064 ◽  
pp. 15-20 ◽  
Author(s):  
Rushdya Rabee ◽  
Mona F. Ali ◽  
Abdel Gawaad Ali Fahmy ◽  
Sawsan Fakhry Halim
Keyword(s):  
Mechanical Properties ◽  
Ph Value ◽  
Protective Layer ◽  
Color Difference ◽  
Styrene Butadiene Rubber ◽  
Infrared Spectrometry ◽  
Butadiene Rubber ◽  
Elongation At Break ◽  
Before And After ◽  
Styrene Butadiene

Leather has been used in Egypt since 4000 BC. Ancient Egyptians used leather as shrouds, bookbinding and manuscripts. This research aims to find a way to protect archeological leather from damage by environmental factors, without losing their archaeological appearance. Leather samples were subjected to ageing in order to simulate archaeological leather. Styrene butadiene rubber was used to coat the leather samples. Then the leather samples were dipped (immersed) in a bath containing SBR dissolved in toluene with concentrations varies from 1 to 5% by weight. The effect of leather/ SBR reinforcement was evaluated by Fourier Transform Infrared Spectrometry (FTIR) and measuring the mechanical properties (tensile strength and elongation at break (%), color difference (ΔE) and lightness (L), pH value before and after ageing. In addition, Scanning Electron Microscope (SEM) was used to study the surface morphology of samples. Finally, all samples were subjected to ageing after reinforcement. The results revealed that reinforcement of leather samples by SBR solutions having concentration 3 % gave the best results among other concentrations. The mechanical properties of treated samples were enhanced with reduction in the ΔE values. The results also showed that the pH values of the treated samples did not change even after further aging. SEM scans evidenced that SBR filled the leather surface cracks besides the formation of a protective layer on the leather surface.

Homogeneous Modifier-Treated AlSi10Mg Alloy: Microstructure and Mechanical Properties

2019 ◽  
Author(s):  
Tomasz Lipiński
Keyword(s):  
Mechanical Properties ◽  
Cooling Rate ◽  
Relative Elongation ◽  
Beta Phase ◽  
Alpha Phase ◽  
Hypoeutectic Alloy ◽  
Hardness Tests ◽  
Before And After ◽  
Alloy Microstructure ◽  
Large Primary

The microstructure of an unmodified hypoeutectic Al–Si alloy comprises large primary alpha phase and eutectic alpha phase dendrites and eutectic beta phase crystals. The mechanical properties of silumins can be improved through chemical modification. This article discusses the modification of an EN AC-AlSi10Mg hypoeutectic alloy with the use of a modifier made of processed alloys and an Al–Si alloy solidified at the velocity of 373, 473, 573, and 673 K/s. The applied alloys were referred to as homogeneous modifiers. The content of modifiers in the silumin alloy reached 0.3%–1.5% by weight. The alloy was subjected to tensile strength, relative elongation, and hardness tests before and after modification. The alloy was cast into a sand mold. The results of the study indicate that alloy microstructure can be modified and its mechanical properties can be improved by incorporating the proposed homogeneous modifiers into a liquid alloy. Mechanical properties were improved when an Al–Si modifier with higher silicon content than the modified alloy was used and when the cooling rate was increased to 573 K/s. A further increase in the cooling rate of the modifier did not lead to a significant improvement in the mechanical properties.

Silica Encapsulation of SrAl2O4:Eu2+, Dy3+ Phosphors by Sol-Gel Method

2016 ◽  
Vol 680 ◽  
pp. 224-227 ◽  
Author(s):  
Huan Wang ◽  
Xiao Ping Liang ◽  
Kai Liu ◽  
Qian Qian Zhou ◽  
Jun Wang ◽  
...  
Keyword(s):  
Water Resistance ◽  
Ph Value ◽  
Solid Phase ◽  
Sol Gel ◽  
Phase Method ◽  
Dense Layer ◽  
Physical Absorption ◽  
Before And After ◽  
Solid Phase Method ◽  
Silica Encapsulation

SrAl2O4:Eu2+,Dy3+ phosphors were synthesized under different temperature by high temperature solid phase method. Encapsulation modification of SrAl2O4:Eu2+,Dy3+ by using SiO2glycol were made over chemically unstable against water. Photoluminescence measurement result shows that when the sintering temperature is 1300 °C, the initial afterglow brightness of SrAl2O4:Eu2+,Dy3+ is up to the highest, 12101 mcd/m2. FTIR results showed that new IR peaks at 1085 cm−1 due to the vibration of Si-O-Si and at 931cm−1 due to the vibration of Si-O-Al appeared after silica encapsulation. This verified that the silica encapsulation is not only a physical absorption process but also involving chemical bonding process. Both phosphors before and after encapsulation have same emission peak at 510 nm. A dense layer of silica formed on phosphor surface has the highest water-resistance after being encapsulated for 2h under the condition of pH 4 and encapsulation amount 10:1. The pH value of aqueous solution contained phosphor was steadily 8, and the initial afterglow brightness decreased only by 9%, that is, from 12101 to 11011 mcd/m2.

scholarly journals The influence of various pH values on the aerogel physical properties by sol-gel technique

2019 ◽  
Vol 17 (41) ◽  
pp. 75-81
Author(s):  
Baha Fakhry Shehab
Keyword(s):  
Physical Properties ◽  
Ph Value ◽  
Ambient Pressure ◽  
Sol Gel ◽  
Silica Aerogels ◽  
Spectroscopic Studies ◽  
Ambient Pressure Drying ◽  
Ph Values ◽  
Bet Method ◽  
The Fourier Transform

Hydrophobic silica aerogels were successfully preparation by an ambient pressure drying method from sodium silicate (Na2SiO3) with different pH values (5, 6, 7, 8, 9 and 10). In this study, acidic HCl (1M), a basic NH4OH (1M) were selected as a catalyst to perform the surface modification in a TMCS (trimethylchlorosilane) solution. The surface chemical modification of the aerogels was assured by the Fourier transform infrared (FTIR) spectroscopic studies. Other physical properties, such as pore volume and pore size and specific surface area were determined by Brunauer-Emmett- Teller (BET) method. The effect of pH values on the bulk density of aerogel. The sol–gel parameter pH value in the sol, have marked effects on the physical properties of the silica aerogels produced by this technique. The density and the hydrophobic tendency of the aerogels were significantly influenced.

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