scholarly journals Effect of Synthesis Temperature on the Crystallization and Growth of In Situ Prepared Nanohydroxyapatite in Chitosan Matrix

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Habiba Elhendawi ◽  
R. M. Felfel ◽  
Bothaina M. Abd El-Hady ◽  
Fikry M. Reicha
Keyword(s):  
Particle Size ◽  
Biomedical Applications ◽  
Particle Growth ◽  
Synthesis Temperature ◽  
Molar Ratio ◽  
Processing Temperature ◽  
Hydroxyapatite Nanoparticles ◽  
Chitosan Matrix ◽  
Coprecipitation Technique

Hydroxyapatite nanoparticles (nHA) have been used in different biomedical applications where certain particle size distribution and morphology are required. Chitosan/hydroxyapatite (CS/HA) nanocomposites were prepared using in situ coprecipitation technique and the effect of the reaction temperature on the crystallization and particle growth of the prepared nanohydroxyapatite particles was investigated. The composites were prepared at different synthesis temperatures (−10, 37, and 60°C). XRD, FTIR, thermal analysis, TEM and SEM techniques were used to characterize the prepared specimens. It was found that the increase in processing temperature had a great affect on particle size and crystal structure of nHA. The low temperature (−10°C) showed inhabitation of the HA growth in c-direction and low crystallinity which was confirmed using XRD and electron diffraction pattern of TEM. Molar ratio of the bone-like apatite layer (Ca/P) for the nanocomposite prepared at 60°C was higher was higher than the composites prepared at lower temperatures (37 and −10°C).

Biocompatibility of Carbonated Hydroxyapatite Nanoparticles with Different Crystallinities

2011 ◽  
Vol 493-494 ◽  
pp. 331-336 ◽  
Author(s):  
Elena Mavropoulos ◽  
Moema Hausen ◽  
Andrea Machado Costa ◽  
Silvia Raquel Albuquerque ◽  
Gutemberg Alves ◽  
...  
Keyword(s):  
Particle Size ◽  
Metabolic Activity ◽  
Biomedical Applications ◽  
Synthesis Temperature ◽  
Hydroxyapatite Nanoparticles ◽  
Synthetic Material ◽  
Confluent Monolayer ◽  
Dental Surgery ◽  
Carbonated Apatite ◽  
High Metabolic Activity

Carbonated apatite (CHA) is commonly considered a promising synthetic material for biomedical applications in orthopedic and dental surgery due to its biocompatibility, bioresorption and bioactivity. CHA5, CHA37 and CHA90 powders were synthesized from wet method and the DRX patterns showed that the crystallinity and particle size of CHA samples increased proportionally with the synthesis temperature. Powder extracts medium were obtained from each sample to interact with MC3T3-E1 osteoblastics cells. It was evaluated morphology, citotoxicity, pH and Ca2+ concentration. Citotoxicity assays showed high metabolic activity on all samples when compared to control. The polygonal shaped and the confluent monolayer observed in control cells progressively changed according to the crystallinity increase of samples. Cells under mitosis and spindle-like shaped where the main alterations observed. In addition the cell viability could be sensitive to the acid reactivity and crystallinity of carbonated apatite samples.

Synthesis and sintering of SiC under high pressure and high temperature

1999 ◽  
Vol 14 (3) ◽  
pp. 906-911 ◽  
Author(s):  
S. K. Bhaumik ◽  
C. Divakar ◽  
S. Usha Devi ◽  
A. K. Singh
Keyword(s):  
Crystal Structure ◽  
Particle Size ◽  
High Pressure ◽  
Silicon Powder ◽  
Synthesis Temperature ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microscopic Studies ◽  
Simultaneous Synthesis

Starting from elemental powders, simultaneous synthesis and compaction of SiC were conducted at 3 GPa pressure and temperatures in the range 2100–2900 K. The sintered compacts were characterized by x-ray diffraction, microhardness measurements, and microscopic studies. The efficiency of formation of SiC was dependent on the particle size of the silicon powder, crystallinity of the reactant carbon, molar ratio of silicon and carbon, and synthesis temperature and time. Carbon in excess of the stoichiometric amount was required to obtain compacts free from residual silicon. The SiC samples, with a Si: C molar ratio 1: 1.05, prepared at 2100 K for 300 s had a density and hardness of 3.21 g/cm3 (98.8% of theoretical density) and 22 GPa, respectively. The crystal structure of the SiC depended on the synthesis temperature. Pure β–SiC in the temperature range 2100–2500 K, and a mixture of α– and β–SiC above 2500 K were obtained. The β–SiC was highly crystalline and nearly defect-free.

Synthesis and characterization of polyaniline nanomaterials with different molar ratio of monomer

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Priyanka S ◽  
Dhachanamoorth N ◽  
Birundha B
Keyword(s):  
Particle Size ◽  
Initial Conditions ◽  
Oxidative Polymerization ◽  
Molar Ratio ◽  
Synthesis Process ◽  
Chemical Oxidative Polymerization ◽  
Good Tool ◽  
Particle Size Analyzer ◽  
Ft Ir

Formation of polymer nanomaterials are achieved by the process of polymerization and there was an availability of different methods such as chemical oxidative polymerization,electro chemical polymerization, In-situ oxidative polymerization and emulsion polymerization etc., Many monomers combine to form polymers under certain conditions by chemical reactions between the monomers. The chemical oxidative polymerization was most commonly used method to synthesize PANI and the synthesis process involved various molar ratio of aniline (0.1M, 0.2M, 0.3M) in which APS was used as an oxidant with dopant of HCl. This study revealed that the properties changed based on their initial conditions. The prepared aromatic polyaniline was characterized by FT-IR, UV-VIS,Particle size analyzer techniques and anti-bacterial activity of the sample was analyzed.FT-IR spectroscopy gives deep view of many  functional groups that were present in a system by measuring vibrational frequencies of chemical bonds involved. UV-VIS was a good tool to identify, characterize and to study the optical properties of nanomaterials.In particle size analyzer, the size of a particle was measured using the instrument laser diffraction particle size analyzer (SALD-2300). The synthesized polyaniline had the tendency to resist the growth of both gram positive and gram negative bacteria. These organic conducting polymers were sometimes called “smart polymers” and have varies application in medical, OLED, solar cell, batteries and sensor etc.,

scholarly journals Model simulations of the chemical and aerosol microphysical evolution of the Sarychev Peak 2009 eruption cloud compared to in-situ and satellite observations

2017 ◽  
Author(s):  
Thibaut Lurton ◽  
Fabrice Jégou ◽  
Gwenaël Berthet ◽  
Jean-Baptiste Renard ◽  
Lieven Clarisse ◽  
...  
Keyword(s):  
Particle Size ◽  
Stratospheric Ozone ◽  
Volcanic Eruptions ◽  
Particle Growth ◽  
Climate Impact ◽  
Stratospheric Aerosol ◽  
Stratospheric Chemistry ◽  
The Impact ◽  
Sarychev Peak

Abstract. Volcanic eruptions impact climate through the injection of sulfur dioxide (SO2), which is oxidized to form sulfuric acid aerosol particles that can enhance the stratospheric aerosol optical depth (SAOD). Besides large-magnitude eruptions, moderate-magnitude eruptions such as Kasatochi in 2008 and Sarychev Peak in 2009 can have a significant impact on stratospheric aerosol and hence climate. However, uncertainties remain in quantifying the atmospheric and climatic impacts of the 2009 Sarychev Peak eruption due to limitations in previous model representations of volcanic aerosol microphysics and particle size, whilst biases have been identified in satellite estimates of post-eruption SAOD. In addition, the 2009 Sarychev Peak eruption co-injected hydrogen chloride (HCl) alongside SO2, whose potential stratospheric chemistry impacts have not been investigated to date. We present a study of the stratospheric SO2-particle-HCl processing and impacts following Sarychev Peak eruption, using the CESM1(WACCM)-CARMA sectional aerosol microphysics model (with no a priori assumption on particle size). The Sarychev Peak 2009 eruption injected 0.9 Tg of SO2 into the upper troposphere and lower stratosphere (UTLS), enhancing the aerosol load in the Northern hemisphere. The post-eruption evolution of the volcanic SO2 in space and time are well reproduced by the model when compared to IASI (Infrared Atmospheric Sounding Interferometer) satellite data. Co-injection of 27 Gg HCl causes a lengthening of the SO2 lifetime and a slight delay in the formation of aerosols, and acts to enhance the destruction of stratospheric ozone and mono-nitrogen oxides (NOx) compared to the simulation with volcanic SO2 only. We therefore highlight the need to account for volcanic halogen chemistry when simulating the impact of eruptions such as Sarychev on stratospheric chemistry. The model-simulated evolution of effective radius (reff), reflects new particle formation followed by particle growth that enhances reff to reach up to 0.2 µm on zonal average. Comparisons of the model-simulated particle number and size-distributions to balloon-borne in-situ stratospheric observations over Kiruna, Sweden, in August and September 2009, and over Laramie, U.S.A., in June and November 2009 show good agreement and quantitatively confirms the post-eruption particle enhancement. We show that the model-simulated SAOD is consistent with that derived from OSIRIS (Optical Spectrograph and InfraRed Imager System) when both the saturation bias of OSIRIS and the fact that extinction profiles may terminate well above the tropopause are taken into account. Previous modelling studies (involving assumptions on particle size) that reported agreement to (biased) post-eruption estimates of SAOD derived from OSIRIS likely underestimated the climate impact of the 2009 Sarychev Peak eruption.

Effect of Temperature and Vapor-phase Encapsulation on Particle Growth and Morphology

1999 ◽  
Vol 14 (4) ◽  
pp. 1664-1671 ◽  
Author(s):  
Sheryl H. Ehrman ◽  
Maria I. Aquino-Class ◽  
Michael R. Zachariah
Keyword(s):  
Particle Size ◽  
Vapor Phase ◽  
Particle Growth ◽  
Effect Of Temperature ◽  
Transmission Electron Micrograph ◽  
Transmission Electron ◽  
Size And Morphology ◽  
Silicon And Germanium ◽  
Increasing Temperature

The effect of in situ vapor phase salt-encapsulation on particle size and morphology was systematically investigated in a sodium co-flow/furnace reactor. The temperature of the furnace was varied, and the primary particle size and degree of agglomeration of the resulting silicon and germanium particles were determined from transmission electron micrograph images of particles sampled in situ. Particle size increased with increasing temperature, a trend expected from our understanding of particle formation in a high-temperature process in the absence of an encapsulant. Germanium, which coalesces faster than silicon, formed larger particles than silicon at the same temperatures, also in agreement with observations of particle growth in more traditional aerosol processes. At the highest temperatures, unagglomerated particles were formed, while at low temperatures, agglomerated particles were formed, with agglomerate shape following the shape of the salt coating.

scholarly journals Continuous Flow Synthesis of ZIF-8 Biocomposites with Tuneable Particle Size

2020 ◽  
Author(s):  
Francesco Carraro ◽  
Jason D. Williams ◽  
Mercedes Linares-Moreau ◽  
chiara parise ◽  
Weibin Liang ◽  
...  
Keyword(s):  
Particle Size ◽  
Continuous Flow ◽  
Continuous Production ◽  
Particle Growth ◽  
Research Area ◽  
Zeolitic Imidazolate Framework ◽  
Model Protein ◽  
Kinetics Of ◽  
Specific Particle

Zeolitic Imidazolate Framework (ZIF) biocomposites show the capacity to protect and deliver bio-therapeutics. To date, the progress in this research area is based on laboratory batch methods. To further explore the potential of ZIF-biocomposites for application to biomedicine and biotechnology, the continuous production of ZIF-biocomposites of specific particle size is desirable. We report the first continuous flow synthetic method for the encapsulation of a model protein (BSA) and a clinical therapeutic (α1-antitrypsin, AAT) in ZIF-8. We studied the in situ kinetics of nucleation, growth and crystallization of BSA-ZIF-8 by SAXS. By controlling the injection time of ethanol, we could quench the particle growth via ethanol-induced crystallization. The particle size of the biocomposite was tuned in the 40-100 nm range by varying residence time prior to introduction of ethanol.<br>

Characterization of nanophase titania particles synthesized using in situ steric stabilization

1997 ◽  
Vol 12 (7) ◽  
pp. 1755-1765 ◽  
Author(s):  
A. G. Gaynor ◽  
R. J. Gonzalez ◽  
R. M. Davis ◽  
R. Zallen
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Phase Transformation ◽  
High Water ◽  
Molar Ratio ◽  
Transformation Behavior ◽  
X Ray ◽  
Infrared Techniques

Ultrafine titania particles were synthesized from titanium tetraethoxide (TEOT) dissolved in ethanol. The concentration of water and of the soluble polymer hydroxypropylcellulose (HPC) were varied to control particle size. The HPC adsorbed onto the titania particles during growth, providing a steric barrier to aggregation. Electron microscopy showed that particles smaller than 70 nm were formed at high water concentrations (R > 120 where R is the molar ratio [H2O]/[TEOT]) and in the presence of HPC. The annealing-induced, phase-transformation behavior of these particles (amorphous → anatase → rutile) from 100 to 1000 °C was characterized by x-ray, Raman, and infrared techniques. The conversion of anatase to rutile occurred more readily for particles made at high water concentrations and with HPC. For particles formed by premixing TEOT with HPC prior to hydrolysis at R = 155, an 800 °C anneal yielded a rutile fraction exceeding 95%; particles made at R = 5.5 with no HPC showed negligible conversion at this temperature.

scholarly journals Reaction Kinetics and Morphological Study of TiNb2O7 Synthesized by Solid-State Reaction

2017 ◽  
Vol 62 (2) ◽  
pp. 1051-1056
Author(s):  
S.H. Choi ◽  
B. Ali ◽  
K.S. Choi ◽  
S.K. Hyun ◽  
J.J. Sim ◽  
...  
Keyword(s):  
Particle Size ◽  
Solid State ◽  
Reaction Kinetics ◽  
Lithium Ion ◽  
Cost Effective ◽  
Synthesis Temperature ◽  
Reaction Rate Constant ◽  
Molar Ratio ◽  
Synthesis Process ◽  
Quantitative Phase Analysis

AbstractAlthough TiNb2O7is regarded as a material with high application potential in lithium-ion batteries (LIBs) and solid-oxide fuel cells (SOFCs), it has been difficult to find suitable cost-effective conditions for synthesizing it on a commercial scale. In this study, TiNb2O7compounds were synthesized by a solid state synthesis process. For stoichiometrically precise synthesis of the TiNb2O7phase, the starting materials, TiO2and Nb2O5were taken in a 1:1 molar ratio. Activation energy and reaction kinetics of the system were investigated at various synthesis temperatures (800,1000,1200, and 1400°C) and for various holding durations (1,5,10, and 20 h). Furthermore, change in the product morphology and particle size distribution were also evaluated as a function of synthesis temperature and duration. Additionally, quantitative phase analysis was conducted using the Rietveld refinement method. It was found that increases in the synthesis temperature and holding time lead to increase in the mean particle size from 1 to 4.5 μm. The reaction rate constant for the synthesis reaction was also calculated.

Continuous Flow Synthesis of ZIF-8 Biocomposites with Tuneable Particle Size

2020 ◽  
Author(s):  
Francesco Carraro ◽  
Jason D. Williams ◽  
Mercedes Linares-Moreau ◽  
chiara parise ◽  
Weibin Liang ◽  
...  
Keyword(s):  
Particle Size ◽  
Continuous Flow ◽  
Continuous Production ◽  
Particle Growth ◽  
Research Area ◽  
Zeolitic Imidazolate Framework ◽  
Model Protein ◽  
Kinetics Of ◽  
Specific Particle

Zeolitic Imidazolate Framework (ZIF) biocomposites show the capacity to protect and deliver bio-therapeutics. To date, the progress in this research area is based on laboratory batch methods. To further explore the potential of ZIF-biocomposites for application to biomedicine and biotechnology, the continuous production of ZIF-biocomposites of specific particle size is desirable. We report the first continuous flow synthetic method for the encapsulation of a model protein (BSA) and a clinical therapeutic (α1-antitrypsin, AAT) in ZIF-8. We studied the in situ kinetics of nucleation, growth and crystallization of BSA-ZIF-8 by SAXS. By controlling the injection time of ethanol, we could quench the particle growth via ethanol-induced crystallization. The particle size of the biocomposite was tuned in the 40-100 nm range by varying residence time prior to introduction of ethanol.<br>

scholarly journals Multifunctional Hydroxyapatite/Silver Nanoparticles/Cotton Gauze for Antimicrobial and Biomedical Applications

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 429
Author(s):  
Mohamed M. Said ◽  
Mohamed Rehan ◽  
Said M. El-Sheikh ◽  
Magdy K. Zahran ◽  
Mohamed S. Abdel-Aziz ◽  
...  
Keyword(s):  
Biomedical Applications ◽  
Antimicrobial Activities ◽  
Uv Protection ◽  
Hydroxyapatite Nanoparticles ◽  
Ag Nps ◽  
Cotton Gauze ◽  
Cationic Modification ◽  
Medical Textiles ◽  
Anti Inflammation

Medical textiles have played an increasingly important protection role in the healthcare industry. This study was aimed at improving the conventional cotton gauze for achieving advanced biomedical specifications (coloration, UV-protection, anti-inflammation, and antimicrobial activities). These features were obtained by modifying the cotton gauze fabrics via in-situ precipitation of hydroxyapatite nanoparticles (HAp NP), followed by in-situ photosynthesis of silver (Ag) NPs with ginger oil as a green reductant with anti-inflammation properties. The HAp-Ag NPs coating provides good UV-protection properties. To further improve the HAp and Ag NPs dispersion and adhesion on the surface, the cotton gauze fabrics were modified by cationization with chitosan, or by partial carboxymethylation (anionic modification). The influence of the cationic and anionic modifications and HAp and Ag NPs deposition on the cotton gauze properties (coloration, UV-protection, antimicrobial activities, and water absorption) was thoroughly assessed. Overall, the results indicate that chemical (anionic and cationic) modification of the cotton gauze enhances HAp and Ag NPs deposition. Chitosan can increase biocompatibility and promotes wound healing properties of cotton gauze. Ag NP deposition onto cotton gauze fabrics brought high antimicrobial activities against Candida albicans, Gram-positive and Gram-negative bacteria, and improved UV protection.

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