Template Polymerization of Acrylamide in Ethanol/Water Mixtures

2016 ◽  
Vol 69 (10) ◽  
pp. 1149
Author(s):  
Jie Dong ◽  
Xiang'an Yue ◽  
Jie He
Keyword(s):  
Molecular Weight ◽  
Particle Size ◽  
Monomer Concentration ◽  
Volume Ratio ◽  
Polyvinyl Butyral ◽  
Template Polymerization ◽  
Transmission Electron ◽  
Mean Diameter ◽  
The Mean ◽  
Concentration Threshold

Irregular hollow polyacrylamide (PAAm) particles with the mean diameter varying from 125 to 413 nm were prepared in ethanol/water mixtures by template polymerization using polyvinyl butyral (PVB) microspheres as the template and 2,2′-azobisisobutyronitrile (AIBN) as the initiator. The influence of the solvent composition, monomer concentration, and template concentration on the yield, molecular weight, and particle size of PAAm were investigated. Decreasing the volume ratio of ethanol to water or increasing the monomer concentration can increase the yield, molecular weight, and particle size of PAAm. The monomer concentration threshold for coagulum-free polymerization is 6 % (w/v). Although the PVB concentration does not show significant influence on the yield, molecular weight, and particle size of PAAm, keeping the PVB concentration between 0.1 and 0.3 % (w/v) is the key to forming PVB microspheres. The formation of PAAm particles is discussed based on transmission electron microscopy results, it is concluded that the shrinkage and dehydration on hollow PAAm particles, which is caused by the removal of templates, results in the formation of micro-sized irregular hollow PAAm particles.

The Preparation Of PLGA-PLL-Peg Nanoparticles Simultaneously Loaded With Daunorubicin and Tetrandrine By Modified Double-Emulsion Method

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 4918-4918
Author(s):  
Ran Liu ◽  
Yonglu Wang ◽  
Liyao Wang ◽  
Jian Cheng ◽  
Guohua Xia ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Particle Size ◽  
Aqueous Phase ◽  
Conflicts Of Interest ◽  
Double Emulsion ◽  
Volume Ratio ◽  
Processing Parameters ◽  
Diffusion Method ◽  
Transmission Electron ◽  
Efficient Delivery

Abstract A functional polymer composed of PLGA, PLL and PEG was synthesized, which was used as carrier material for fabricating drug delivery system of nanoparticles. PLGA-PLL-PEG nanoparticles simultaneously loaded with daunorubicin (DNR) and tetrandrine (Tet) were prepared in order to inhibit MDR activity and enhance the antitumor activity of DNR. A modified double-emulsion solvent evaporation/diffusion method was used to increase the incorporation of DNR (hydrophilic) and Tet (hydrophobic) into PLGA-PLL-PEG nanoparticles (NPs). The influence of various processing parameters on particle size and drug loadings were investigated systematically, such as the molecular weight, such as the molecular weight and concentration of PLGA-PLL-PEG, volume ratio of acetone to dichloromethane, PVA concentration in the external aqueous phase, the volume ratio of internal aqueous phase to external aqueous phase and the surfactants of internal aqueous phase. The particle size of the nanoparticles produced by optimized formulation and preparation was 213.0±12 nm (n = 3) with low polydispersity index (0.075 ± 0.023, n = 3). Transmission electron microscopy (TEM) examination showed that the morphology of the prepared nanoparticles was spherical in shape with a smooth surface. The drug loadings were 3.63±0.15% for DNR and 4.27±0.13% for Tet (n = 3). The entrapment efficiencies were 70.23±1.91% for DNR and 86.5±0.7% for Tet (n = 3). The release of DNR and Tet were sustained over one week. The PLGA-PLL-PEG-NPs formulation was potentially useful for hydrophilic and hydrophobic drugs that require efficient delivery to cancer cells. Disclosures: No relevant conflicts of interest to declare.

Rapid Synthesis of Non-Crosslinked and Monodisperse Polystyrene Microspheres

2013 ◽  
Vol 634-638 ◽  
pp. 2222-2227
Author(s):  
Chang Ming Ye ◽  
Yan Qin Yang ◽  
Feng Dong ◽  
Li Li ◽  
Xi Long Hao ◽  
...  
Keyword(s):  
Dispersion Polymerization ◽  
Monomer Concentration ◽  
Volume Ratio ◽  
Polymerization Process ◽  
Polystyrene Microspheres ◽  
Fenton Reagent ◽  
Uniform Size ◽  
Transmission Electron ◽  
New Synthesis ◽  
Monodisperse Polystyrene

Non-crosslinked and monodisperse polystyrene (PS) microspheres showing uniform size were synthesized by using a dispersion polymerization technique in the presence of the Fenton reagent (FeSO4/H2O2) as an initiator. The effects of stabilizer dosage, monomer concentration, volume ratio of dispersion medium and reaction time on both the morphology and dispersity of PS microspheres were investigated. The results of transmission electron microscopy (TEM) and field emission scanning electron microscope (FESEM) indicated that the obtained PS microspheres are perfect with uniform size of about 170 nm under the optimum experimental condition. On the basis of the experimental results, the mechanism of PS polymerization was proposed, which should be helpful to guide the preparation of polymer microspheres with desired uniform size. In comparison with the conventional emulsion polymerization, this new synthesis technique with the Fenton reagent exhibits some advantages such as being a simple and fast polymerization process without deoxygenation.

scholarly journals Size-resolved cloud condensation nuclei (CCN) activity and closure analysis at the HKUST Supersite in Hong Kong

2014 ◽  
Vol 14 (18) ◽  
pp. 10267-10282 ◽  
Author(s):  
J. W. Meng ◽  
M. C. Yeung ◽  
Y. J. Li ◽  
B. Y. L. Lee ◽  
C. K. Chan
Keyword(s):  
Particle Size ◽  
Hong Kong ◽  
Atmospheric Aerosols ◽  
Cloud Condensation Nuclei ◽  
Particle Diameter ◽  
Volume Ratio ◽  
Condensation Nuclei ◽  
Mixing State ◽  
Scanning Mobility Particle Sizer ◽  
The Mean

Abstract. The cloud condensation nuclei (CCN) properties of atmospheric aerosols were measured on 1–30 May 2011 at the HKUST (Hong Kong University of Science and Technology) Supersite, a coastal site in Hong Kong. Size-resolved CCN activation curves, the ratio of number concentration of CCN (NCCN) to aerosol concentration (NCN) as a function of particle size, were obtained at supersaturation (SS) = 0.15, 0.35, 0.50, and 0.70% using a DMT (Droplet Measurement Technologies) CCN counter (CCNc) and a TSI scanning mobility particle sizer (SMPS). The mean bulk size-integrated NCCN ranged from ~500 cm−3 at SS = 0.15% to ~2100 cm−3 at SS = 0.70%, and the mean bulk NCCN / NCN ratio ranged from 0.16 at SS = 0.15% to 0.65 at SS = 0.70%. The average critical mobility diameters (D50) at SS = 0.15, 0.35, 0.50, and 0.70% were 116, 67, 56, and 46 nm, respectively. The corresponding average hygroscopic parameters (κCCN) were 0.39, 0.36, 0.31, and 0.28. The decrease in κCCN can be attributed to the increase in organic to inorganic volume ratio as particle size decreases, as measured by an Aerodyne high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). The κCCN correlates reasonably well with κAMS_SR based on size-resolved AMS measurements: κAMS_SR = κorg × forg + κinorg × finorg, where forg and finorg are the organic and inorganic volume fractions, respectively, κorg = 0.1 and κinorg = 0.6, with a R2 of 0.51. In closure analysis, NCCN was estimated by integrating the measured size-resolved NCN for particles larger than D50 derived from κ assuming internal mixing state. Estimates using κAMS_SR show that the measured and predicted NCCN were generally within 10% of each other at all four SS. The deviation increased to 26% when κAMS was calculated from bulk PM1 AMS measurements of particles because PM1 was dominated by particles of 200 to 500 nm in diameter, which had a larger inorganic fraction than those of D50 (particle diameter < 200 nm). A constant κ = 0.33 (the average value of κAMS_SR over the course of campaign) was found to give an NCCN prediction within 12% of the actual measured values. We also compared NCCN estimates based on the measured average D50 and the average size-resolved CCN activation ratio to examine the relative importance of hygroscopicity and mixing state. NCCN appears to be relatively more sensitive to the mixing state and hygroscopicity at a high SS = 0.70% and a low SS = 0.15%, respectively.

An initial test of a method for the estimation of real mean particle size from shadowed samples

1985 ◽  
Vol 31 (7) ◽  
pp. 604-607
Author(s):  
J. H. M. Willison
Keyword(s):  
Particle Size ◽  
Present Method ◽  
Particle Sizes ◽  
Initial Test ◽  
Small Particles ◽  
Mean Particle Size ◽  
Sample Rotation ◽  
Mean Diameter ◽  
The Mean

During shadowing, a "cap" of metal develops on small particles. This cap increases, apparent particle width (measured normal to the shadowing direction) by an extent which cannot be predetermined. The extent of this increase in particle size (here defined as the "cap," X) is estimated in the present method by using opposite (180° sample rotation) bidirectional shadowing. It is argued that the bidirectional cap is the sum of the two unidirectional caps, and therefore that X = 2A − (B + C), where A is the mean bidirectionally shadowed particle size, and B and C are the two mean unidirectionally shadowed particle sizes. As a validation of the method, the mean diameter of air-dried ferritin was estimated and the results appear to confirm the hypothesis (mean diameter by present method, 10.7 ± 0.2 nm; mean diameter by previous methods, 10.89 nm).

Synthesis of Cross-Linked Poly(acrylamide) Microspheres by Dispersion Polymerisation in Aqueous Ammonium Sulfate Solution

2017 ◽  
Vol 70 (7) ◽  
pp. 816
Author(s):  
Jie He ◽  
Saman Aryana ◽  
Jie Dong ◽  
Feng Guo
Keyword(s):  
Ammonium Sulfate ◽  
Sodium Dodecyl ◽  
Monomer Concentration ◽  
Sulfate Solution ◽  
Optimum Conditions ◽  
Ammonium Sulfate Solution ◽  
Transmission Electron ◽  
Precipitation Behaviour ◽  
The Mean ◽  
Poly Acrylamide

Cross-linked poly(acrylamide) microspheres, i.e. PAMBA, with mean diameters ranging from 169.7 to 525.2 nm were prepared by dispersion polymerisation of acrylamide in aqueous ammonium sulfate (AS) solution. N,N′-methylenebis(acrylamide) (MBA), sodium dodecyl sulfate (SDS), and potassium persulfate (KPS) were selected as the cross-linking agent, stabiliser, and initiator, respectively. The basic conditions for producing PAMBA microspheres, such as the salt concentration and monomer concentration, were optimised based on the precipitation behaviour of the polymer and the state of the product obtained after polymerisation. The optimum AS concentration and monomer concentration were determined as 300 and 88 g L−1, respectively. The effects of parameters, such as SDS concentration, MBA concentration, initiator concentration and temperature, on the product morphology and particle size were investigated by dynamic light scattering and transmission electron microscopy. The results show that the optimum conditions for the generation of microspheres are concentrations of 2.2–8.8 g L−1 for SDS, 4–6 g L−1 for MBA, 0.3–1.0 wt-% based on acrylamide for KPS, and the temperature should be kept at 35–45°C. The mean diameter of the microspheres decreases with an increase in SDS concentration and increases with an increase in MBA concentration. The polydispersity of the microspheres increases when SDS concentration exceeds 6.6 g L−1 as well as when MBA concentration increases. The formation mechanism of the products was discussed based on the results.

scholarly journals Comparative Study of Chitosan and Oligochitosan Coatings on Mucoadhesion of Curcumin Nanosuspensions

Pharmaceutics ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2154
Author(s):  
Gye Hwa Shin ◽  
Jun Tae Kim
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Particle Size ◽  
Morphological Changes ◽  
Transmission Electron ◽  
Efficient Delivery ◽  
Ft Ir ◽  
The Mean ◽  
Insoluble Compounds ◽  
Ft Ir Spectroscopy

Curcumin nanosuspensions (Cur-NSs), chitosan-coated Cur-NSs (CS-Cur-NSs), and oligochitosan-coated Cur-NSs (OCS-Cur-NSs) were prepared by using an ultrasonic homogenization technique. The mean particle size of Cur-NSs was 210.9 nm and significantly (p < 0.05) increased to 368.8 nm by CS coating and decreased to 172.8 nm by OCS coating. Encapsulation efficiencies of Cur-NSs, CS-Cur-NSs, and OCS-Cur-NSs were 80.6%, 91.4%, and 88.5%, respectively. The mucin adsorption of Cur-NSs was steeply increased about 3–4 times by CS and OCS coating. Morphological changes of these NSs were studied using circular dichroism spectroscopy, Fourier-transform infrared (FT-IR) spectroscopy, and transmission electron microscopy (TEM). Thus, CS-Cur-NSs and OCS-Cur-NSs showed great potential as mucoadhesive nano-carriers for the efficient delivery of water insoluble compounds like curcumin to the gastrointestinal system.

scholarly journals Particle size control of a monodisperse spherical Y2O3:Eu3+ phosphor and its photoluminescence properties

2007 ◽  
Vol 22 (7) ◽  
pp. 2017-2024 ◽  
Author(s):  
Hyoung Sun Yoo ◽  
Ho Seong Jang ◽  
Won Bin Im ◽  
Jong Hyuk Kang ◽  
Duk Young Jeon
Keyword(s):  
Particle Size ◽  
Size Control ◽  
Volume Ratio ◽  
Precipitation Method ◽  
High Yield ◽  
Prepared Phosphor ◽  
Photoluminescence Properties ◽  
Mean Size ◽  
The Mean ◽  
Pl Intensity

A monodisperse spherical Y2O3:Eu3+ phosphor was prepared by a homogeneous precipitation method. The mean size of the phosphor particles (MSPP) was successfully controlled by changing the volume ratio of normal alcohol (RA) (propanol) in the solvents mixed between deionized water and normal propanol. When the RA was increased from 0 to 0.7, the MSPP decreased while maintaining a high yield of >95%. Although the prepared phosphor samples were fired at the same temperature, the thermal energy was delivered more efficiently into the inner side of the phosphor particles with the decrease of the MSPP. Therefore, the crystallinity and also the photoluminescence (PL) intensity of the phosphor increased with the decrease in the MSPP. In addition, because the numbers of Eu3+ ions located near the particle surfaces increased with the decrease of particle size, the ratio of PL intensity caused by the 5D0–7F2 transition to that caused by 5D0–7F1 transition increased from 10.8 to 12.7 with the decrease in MSPP.

Dynamics of Droplets Impacting on Thin Heated Strips

1988 ◽  
Vol 110 (1) ◽  
pp. 214-220 ◽  
Author(s):  
S. C. Yao ◽  
L. E. Hochreiter ◽  
K. Y. Cai
Keyword(s):  
High Speed ◽  
Nuclear Reactor ◽  
Droplet Diameter ◽  
Volume Ratio ◽  
Two Phase ◽  
Steel Strips ◽  
Mean Diameter ◽  
Size Groups ◽  
Leidenfrost Temperature ◽  
The Mean

Experiments were conducted with water droplets impacting on the edge of thin steel strips that were heated to beyond the Leidenfrost temperature. High-speed movies were taken and analyzed and showed that the shattered droplets were generally bimodal in size distribution. The volume ratio of these two size groups of generated droplets, the mean diameter of droplets, and the ejection angles and velocities of shattered droplets are shown as a function of incoming droplet Weber number, the ratio of incoming droplet diameter to strip thickness, and the offset of the droplet relative to the strip. The data are presented in nondimensional form and correlations are provided for the mean diameter of the shattered droplets. The theoretical limiting conditions of a droplet impacting normally to a large plate and cutting by a strip of zero thickness are analyzed. The present results are compared with those of the limiting conditions. The application to a nuclear reactor spacer grid behavior during two-phase dispersed flow is discussed.

PHOTOCATALYTIC ACTIVITY OF BISMUTH VANADATE FOR THE DEGRADATION OF ORGANIC COMPOUNDS

NANO ◽  
2013 ◽  
Vol 08 (01) ◽  
pp. 1350007 ◽  
Author(s):  
SURENDER KUMAR ◽  
P. D. SAHARE
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Photocatalytic Activity ◽  
Organic Dyes ◽  
Uv Light ◽  
Volume Ratio ◽  
Annealing Treatment ◽  
Complete Removal ◽  
Combustion Method ◽  
Transmission Electron

We synthesized the nanoparticles of Bi4V2O11 with particle size less than 30 nm by combustion method and they were found to be in monoclinic phase (i.e., α-phase), confirmed by X-ray diffraction, Raman and Fourier transform Infrared spectroscopy. Morphology of the α- Bi4V2O11 was analyzed by transmission electron microscopy and scanning electron microscopy techniques. Photocatalytic activity of α- Bi4V2O11 in degradation of common organic dyes, such as, Rhodamine B (Rh B) and Methylene Blue (MB) was investigated under UV irradiation. Furthermore, γ- Bi4V2O11 was obtained by post annealing treatment of α- Bi4V2O11 to investigate the phase transition and size dependent effects on photocatalytic activity. α- Bi4V2O11 has shown better photocatalytic activity compared to γ- Bi4V2O11 which is attributed to its smaller particle size enhancing its surface to volume ratio and being in a different phase. BET measurement is also performed in order to observe the effect of surface area on photocatalytic activity. Complete removal of aqueous Rh B dye was realized after UV light irradiation for 45 min with α- Bi4V2O11 as the photocatalyst.

scholarly journals PIPERINE-LOADED CHITOSAN NANOPARTICLES: PREPARATION AND CHARACTERIZATION

2021 ◽  
Vol 59 (4) ◽  
pp. 480
Author(s):  
Tran Thi Y Nhi ◽  
Cong Duc Trinh ◽  
Thien Do Truong ◽  
Tuan Le Quang ◽  
Hanh Bich Pham ◽  
...  
Keyword(s):  
Particle Size ◽  
Plasma Cholesterol ◽  
Chitosan Nanoparticles ◽  
Black Pepper ◽  
Plasma Cholesterol Level ◽  
Distribution Analysis ◽  
Transmission Electron ◽  
Ft Ir ◽  
The Mean ◽  
Ft Ir Spectroscopy

Abstract – HCTN7. Plasma cholesterol level plays an important role in atherosclerosis and cardiovascular diseases. Piperine, an alkaloid form of black pepper is known to reduce cholesterol uptake. In this paper, piperine-loaded chitosan nanoparticles (CTS-PIP NPs) were prepared by ionic gelation method. Molecular interactions among the components were confirmed by FT-IR spectroscopy. Transmission electron microscopy (TEM) images revealed spherical-shaped nanoparticles with diameter of <100 nm. CTS-PIP NPs displayed positive ζ-potential(ZP) of about 31.6 mV. Dynamic light scattering (DLS) particle size (PS) distribution analysis indicated the mean particle size of CTS-PIP NPs was 245.9 nm, polydispersity index of 31%

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