Macroporous Hydrogels Based on 2-Hydroxyethyl Methacrylate. Part 1. Copolymers of 2-Hydroxyethyl Methacrylate with Methacrylic Acid

2003 ◽  
Vol 68 (4) ◽  
pp. 812-822 ◽  
Author(s):  
Martin Přádný ◽  
Petr Lesný ◽  
Jindřich Fiala ◽  
Jiří Vacík ◽  
Miroslav Šlouf ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Sodium Chloride ◽  
Pore Size ◽  
Methacrylic Acid ◽  
Unit Volume ◽  
Hydroxyethyl Methacrylate ◽  
Diffusion Parameters ◽  
And Diffusion ◽  
Scanning Electron

A series of macroporous crosslinked copolymers of 2-hydroxyethyl methacrylate (HEMA) with methacrylic acid (MA) was prepared in the presence of fractionated particles of sodium chloride. The hydrogels were characterized by the number of pores in unit volume, the pore size, the water content in pores and diffusion parameters. The structure of the hydrogels was followed by confocal and scanning electron microscopy.

The Effect of Indium Mole Fraction on the Growth Behavior of Your InxGa1-xAs Nanowires (NWs) Grown Using MOCVD

2013 ◽  
Vol 667 ◽  
pp. 224-230 ◽  
Author(s):  
Zulkafli Othaman ◽  
Edy Wibowo ◽  
Samsudi Sakrani
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Field Emission ◽  
Mole Fraction ◽  
Growth Mechanism ◽  
Growth Behavior ◽  
Uniform Diameter ◽  
And Diffusion ◽  
Scanning Electron

InxGa1-xAs NWs have been grown with various indium mole fractions (x) using MOCVD. The morphology of InxGa1-xAs NWs was observed using Field Emission-Scanning Electron Microscopy (FE-SEM) in order to study the growth behavior of the NWs. FE-SEM results show that the NWs growth mechanism has changed due to changing of indium mole fraction. At low indium mole fraction, the NWs grew via direct impinging mechanism which has produced NWs with relatively uniform diameter. By increasing the value of x the growth mechanism has transformed to the combination of direct impinging and diffusion of source atoms from the surface of substrate causing tapering of NWs. The degree of tapering increases with increasing value of indium mole fraction. InxGa1-xAs NW grown at x = 0.65 has the highest tapering factor, TF = 12.82, whereas NW grown at x = 0.41 has the lowest tapering factor, TF = 2.76.

The Synthesis of Maghemite and Hematite (γ-Fe2O3, α-Fe2O3) Nanospheres

2007 ◽  
Vol 534-536 ◽  
pp. 157-160 ◽  
Author(s):  
M.A. Dar ◽  
S.G. Ansari ◽  
Rizwan Wahab ◽  
Young Soon Kim ◽  
Hyung Shik Shin
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Iron Oxide ◽  
Pore Size ◽  
Field Emission ◽  
Sol Gel ◽  
Oxide Powder ◽  
Transmission Electron ◽  
Scanning Electron

Maghemite and hematite nanospheres were synthesized by using the Sol-gel technique. The structural properties of these nanosphere powders were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM),and pore size distribution.Hematite phase shows crystalline structures.The mean particle size that resulted from BET and XRD analyses were 4.9 nm and 2 nm. The field emission scanning electron microscopy shows iron-oxide powder is composed of nanosized particles, but in nanosized aggregates (agglomeration of particles). It can be seen from transmission electron microscopy that the size of the particles are very small which is in good agreement with the FESEM and the Xray diffraction. TEM and FESEM confirmed that the iron-oxide powder is composed of sizes from 8 nm to 10 nm. The BET and pore size method were employed for specific surface area determination.

scholarly journals Síntesis y caracterización de xerogeles de sílice obtenidos por la ruta de los atranos

2020 ◽  
Vol 5 (3) ◽  
pp. 37
Author(s):  
Lenin Jose Huerta ◽  
Rebeca Torres Fajardo ◽  
Juan Primera Ferrer
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Differential Scanning Calorimetry ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Water Evaporation ◽  
Scanning Calorimetry ◽  
Xerogel Sample ◽  
Scanning Electron

  En este trabajo se investigó la síntesis de xerogeles de sílice por la vía de los atranos, y se evaluó la influencia de la concentración del agente iniciador (HCl) y la presencia o no del surfactante (CTAB), sobre el tiempo de gelificación y las propiedades texturales de los materiales obtenidos. Las caracterizaciones se realizaron mediante: isotermas de adsorción-desorción de nitrógeno, microscopía electrónica de barrido y calorimetría diferencial de barrido. Los tiempos de gelificación aumentaron en la medida que se disminuyó la concentración del HCl y, en general, los xerogeles preparados presentaron una buena rigidez cuando estos se dejaron a tiempos mayores de 20 horas. La distribución de tamaño de poro (determinada mediante la técnica BJH) para los xerogeles calcinados preparados sin surfactante presentaron un sistema de poro bien definido de 16,4 nm en promedio, mientras los xerogeles calcinados preparados con surfactante no presentaron una distribución de tamaño de poro bien definida, ambos casos mostraron áreas superficiales de alrededor de 580 m2/g. Por calorimetría diferencial de barrido se observaron dos picos para la muestra de xerogel sin surfactante, uno alrededor de 80 °C debido a la evaporación del agua y el otro a 265 °C atribuido a la descomposición de la materia orgánica presente en el gel; para la muestra de xerogel con surfactante se observó un pico bien definido a 130 °C, atribuido a la pérdida del agua. Por microscopía electrónica de barrido, en los xerogeles calcinados se observaron poros con tamaños alrededor de los 15 nm.   Palabra clave: Xerogel, atrano, surfactante, sílice, gelificación.   Abstract In this work, the synthesis of silica xerogels by the atrane way was investigated, evaluating: concentration influence of the initiating agent (HCl) and the presence or not of the surfactant (CTAB), over gelation time, and the textural properties of the obtained materials. Characterizations were carried out by nitrogen adsorption-desorption isotherms, scanning electron microscopy, and differential scanning calorimetry. Gelation times increased as the HCl concentration decreased, and, in general, xerogels prepared presented good rigidity when they were aging for times greater than 20 hours. Pore size distribution (determined by the BJH technique) for the calcined xerogels prepared without surfactant presented a well-defined pore system of 16.4 nm on average, while the calcined xerogels prepared with surfactant did not present a well-defined pore size distribution, both cases showed surface areas of around 580 m2/g. In differential scanning calorimetry, two peaks were observed for the xerogel sample without surfactant, one around 80 °C due to water evaporation, and the other one at 265 °C attributed to the decomposition of organic matter present in the gel; for the surfactant xerogel sample, a well-defined peak was observed at 130 °C, attributed to the loss of water. By scanning electron microscopy, pores with sizes around 15 nm in calcined xerogels were observed.   Keywords: Xerogel, atrane, surfactant, silica, gelation.  

Melt electro written three-dimensional scaffolds engineered as oral microcosm models-an in vitro study.

2020 ◽  
Author(s):  
Srinivas Ramachandra ◽  
Abdulla Abdal-hay ◽  
Pingping Han ◽  
Ryan Lee ◽  
Saso Ivanovski
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Confocal Microscopy ◽  
Pore Size ◽  
Next Generation ◽  
16S Sequencing ◽  
3 Dimensional ◽  
Wide Range ◽  
Scanning Electron ◽  
Medical Grade

<p><strong>Introduction</strong>: Biofilms are 3-dimensional (3D) aggregates of microorganisms that are associated with a wide range of diseases. Although there have been several studies investigating biofilm formation on two-dimensional substrates, the use of 3D substrates may result in more representative and clinically relevant models. Accordingly, the aim of this study was to compare the growth of biofilms in the 3D substrates against biofilms grown in 2D substrates.<br /><strong>Material and Methods:</strong> Two grams of medical grade polycaprolactone (PCL) were loaded into a plastic Luer-lock 3 ml syringe and a 23G needle was used as a spinneret. The syringe was placed in a melt electro-writing (MEW) device to obtain fine fibers under controlled parameters. The 3-dimensional MEW PCL scaffolds were manufactured and characterised with an overall thickness of ~ 0.8 mm, with ~ 15 μm diameter fibers and ordered pore sizes of either 100 or 250 µm. PCL films employed as 2D substrates were manufactured by dissolving 10 gms of PCL in 100 ml chloroform and stirred for 3 h to obtain a transparent solution. Then, the solution was cast in glass petri dishes and dried to remove all organic solvents. In addition, commercial hydroxyapatite discs were also used as 2D controls. Unstimulated saliva from six healthy donors (gingival health) were used to grow biofilms. The formed biofilms were assessed at day 4, day 7 and day 10 using crystal violet assay, confocal microscopy, scanning electron microscopy and next-generation 16s sequencing.<br /><strong>Results:</strong> The results demonstrates that 3D PCL scaffolds dramatically enhanced biofilm biomass and thickness growth compared to that of the 2D controls. Confocal microscopy of biofilms at day 4 stained with SYTO 9 and propidium iodide showed thickness of biofilms in 2D substrates were 39 µm and 81µm for hydroxyapatite discs and PCL films, respectively. Biofilms in 3D substrates were 250 µm and 338 µm for MEW PCL 100µm pore size and MEW PCL 250 µm pore size, respectively. Similar results were noticed at day 7 and day 10. Scanning electron microscopy showed biofilm bridges formed over the fibers of the MEW scaffolds. Pilot trials of next generation sequencing detected similar taxa in biofilms formed in 3D scaffolds compared to that of 2D substrates.<br /><strong>Discussion:</strong> We have successfully investigated a 3D biofilm growth model using 3D medical grade PCL scaffolds. Thicker biofilms can be conveniently grown using this inexpensive static model. This will facilitate 3D microbial community studies that are more clinically relevant and improve our understanding of biofilm-associated disease processes.</p> <p> </p>

Synthesis of Nano Onion-Like Fullerenes Using Iron Supported on Sodium Chloride as Catalyst by Decomposing Acetylene

2011 ◽  
Vol 393-395 ◽  
pp. 370-372
Author(s):  
Cun Jing Wang ◽  
Peng Yao ◽  
Gai Rong Chen
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Sodium Chloride ◽  
Catalytic Decomposition ◽  
Argon Atmosphere ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Heat Treated ◽  
Scanning Electron

Catalytic decomposition of acetylene was carried out at 400 °C using iron supported on sodium chloride as catalyst and the product was heat-treated at 650 °C under an argon atmosphere for 2 h directly. The sample was examined by scanning electron microscopy, high resolution transmission electron microscopy and X-ray diffraction. The results show that nano onion-like fullerenes encapsulating Fe cores with diameters in the range 20-50 nm were obtained.

Understanding variations in reservoir porosity in the Eagle Ford Shale using scanning electron microscopy: implications for basin modelling

2020 ◽  
Vol 484 (1) ◽  
pp. 229-239 ◽  
Author(s):  
Mark Osborne ◽  
Herbert Volk
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Organic Matter ◽  
Pore Size ◽  
Source Rocks ◽  
Thermal Maturity ◽  
Eagle Ford Shale ◽  
Eagle Ford ◽  
Basin Modelling ◽  
Scanning Electron

AbstractReliable evaluation of shale-play potential requires robust geological models that can simulate the generation and retention of petroleum, porosity and permeability in source rocks from first principles, and that can be implemented in basin modelling software. To be predictive, such basin models need to be calibrated against observations from real shale plays. A key control on the amount of retained petroleum is the porosity in the shale and the abundance of organic matter. Scanning electron microscopy of argon-ion milled shale samples can potentially reveal systematic variations in the amount of porosity, pore types and distributions across a range of thermal maturities. These observed variations in porosity can be used to calibrate basin modelling outputs and refine predictive models. For these reasons BP has conducted scanning electron microscopy studies of shale plays including the Eagle Ford Shale, a carbonate-rich mudstone sequence of Cenomanian to Turonian age. The results clearly show that the mean pore size decreases as thermal maturity increases and that organic matter-hosted pores are absent in low thermal maturity samples (where vitrinite random reflectance Ro <0.7) and become increasingly more abundant as thermal maturity increases). In moderately mature samples there are organic matter hosted pores that range in pore size from 5 to 500 nm. In highly mature samples, small (<50 nm) organic matter-hosted pores predominate. Our studies reveal that porosity evolution in this organic-rich, fine-grained, carbonate mudrock shows a strong correlation with increasing thermal maturity.

Differential Response of Liverwort (Marchantia polymorpha) Tissue to POST-Applied Quinoclamine

2011 ◽  
Vol 25 (4) ◽  
pp. 580-585
Author(s):  
James E. Altland ◽  
Glenn Wehtje ◽  
Jeff Sibley ◽  
Michael E. Miller ◽  
Charles H. Gilliam ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Pore Size ◽  
Higher Plants ◽  
Differential Sensitivity ◽  
Marchantia Polymorpha ◽  
Pore Area ◽  
Nursery Crops ◽  
Unites States ◽  
Scanning Electron

Quinoclamine is used in Europe, and was under evaluation in the Unites States for the control of liverwort in nursery crops. Liverwort is a nonvascular, chlorophyll-containing plant that can be problematic in greenhouse and nursery crops. POST-applied quinoclamine controls liverwort. However, liverwort structures vary in their sensitivity to POST-applied quinoclamine. Specifically, archegonial receptacles (female) are much more tolerant of quinoclamine than either antheridial receptacles (male) or thalli (leaflike structures). A series of studies were conducted to, first, document the degree of differential sensitivity between tissues to quinoclamine, and second, to determine the basis of this differential sensitivity. The dose that results in 50% of the population being controlled (I50) of antheridial receptacles and juvenile thalli were estimated to be 1.60 and 1.27 kg·ha−1, respectively. TheI50of archegonial receptacles could not be estimated, but exceeded 10.45 kg·ha−1. Chlorophyll content varied between liverwort tissues, but the content did not correlate to quinoclamine sensitivity. Absorption of14C after application of radiolabeled quinoclamine was less in archegonial receptacles than in either antheridial receptacles or thalli. Scanning electron microscopy of the surface of the liverwort tissues revealed that archegonial receptacles had smaller pores (equivalent to stomata in higher plants) than either antheridial receptacles or thalli. The tolerance of archegonial receptacles to quinoclamine can be partially, but not exclusively, attributed to reduced absorption. This reduced absorption may be attributed to the limited pore size and less total pore area of the archegonial receptacles.

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