Bentonite-Based Organoclays as Innovative Flame Retardants Agents for SBS Copolymer

2008 ◽  
Vol 8 (12) ◽  
pp. 6316-6324 ◽  
Author(s):  
M. Comes Franchini ◽  
P. Fabbri ◽  
A. Frache ◽  
G. Ori ◽  
M. Messori ◽  
...  
Keyword(s):  
Flame Retardants ◽  
Morphological Characterization ◽  
Tem Analysis ◽  
Important Functional Property ◽  
Octadecyltrimethylammonium Bromide ◽  
Nitrogen Containing Compounds ◽  
Styrene Butadiene ◽  
Heat Released

Two organophilic bentonites, based on nitrogen-containing compounds, have been synthesised via ion exchange starting from pristine bentonite with octadecyltrimethylammonium bromide (OTAB) and with synthetic melamine-derived N2,N4-dihexadecyl-1,3,5-triazine-2,4,6-triamine (DEDMEL). The chemical and morphological characterization of the organoclays was based on XRD, TEM, Laser Granulometry, X-Ray Fluorescence and CEC capacity. Copoly(styrene-butadiene-styrene)-nanocomposites (SBS-nanocomposites) were obtained by intercalation of the SBS-copolymer into these new organoclays by melt intercalation method. XRD and TEM analysis of the organoclays and of the micro/nano-composites obtained are presented. The effect of the organoclays on the SBS-nanocomposite's flammability properties was investigated using cone calorimeter. An encouraging decrease of 20% in the peak heat released rate (PHRR) has been obtained confirming the important role of melamine's based skeleton and its derived organoclays to act as effective fire retardants and for the improvement of this important functional property in SBS copolymers.

scholarly journals Adsorption of Cellulase on Wrinkled Silica Nanoparticles with Enhanced Inter-Wrinkle Distance

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1799
Author(s):  
Aniello Costantini ◽  
Virginia Venezia ◽  
Giulio Pota ◽  
Aurelio Bifulco ◽  
Valeria Califano ◽  
...  
Keyword(s):  
Silica Nanoparticles ◽  
Morphological Characterization ◽  
Operational Stability ◽  
Successful Outcome ◽  
Glucose Yield ◽  
Transmission Electron ◽  
Ft Ir ◽  
Immobilized Cellulase

Mesoporous silica materials offer a unique opportunity for enzyme immobilization thanks to their properties, such as tuneable pore size, large surface area and easy functionalization. However, a significant enhancement of cellulase enzyme activity entrapped inside the silica pores still represents a challenge. In this work, we immobilized cellulase by adsorption on wrinkled silica nanoparticles (WSNs), obtaining an active and stable biocatalyst. We used pentanol as co-solvent to synthesize WSNs with enhanced inter-wrinkle distance in order to improve cellulase hosting. The physical-chemical and morphological characterization of WSNs and cellulase/WSNs was performed by thermogravimetric (TG), Fourier transform infrared (FT-IR), and transmission electron microscopy (TEM) analyses. The obtained results showed that this matrix generates a favourable microenvironment for hosting cellulase. The results of the catalytic assays and operational stability confirmed the key role of size, morphology and distribution of the pores in the successful outcome of the cellulase immobilization process. The immobilization procedure used allowed preserving most of the secondary structure of the enzyme and, consequently, its catalytic activity. Moreover, the same value of glucose yield was observed for five consecutive runs, showing a high operational stability of the biocatalyst.

scholarly journals Morphological characterization of seeds in Portulacaceae

Phytotaxa ◽  
2013 ◽  
Vol 141 (1) ◽  
pp. 1 ◽  
Author(s):  
Gilberto Ocampo
Keyword(s):  
Cell Walls ◽  
Individual Cell ◽  
Morphological Diversity ◽  
Morphological Characterization ◽  
Seed Morphology ◽  
Important Variation ◽  
Species Complexes ◽  
Multiple Samples

Portulacaceae is a monogeneric family with around 100 species distributed around the world. Seed morphology is diverse in this group, and its variation has been used for taxonomic and identification purposes. However, documentation of seed morphology has focused on a few species complexes or has been limited to specific countries and geographic areas. Moreover, the terminology employed in different investigations is heterogeneous, thus complicating analyses of seed morphological diversity in Portulacaceae. In this study, the seed morphology of 58 samples representing 49 species, 9 subspecies, and 2 cultivars of Portulaca was documented with the use of scanning electron microscopy (SEM). Based on the examination of the resulting images, a set of morphological features for describing the general shape of the seeds and their individual cell features is proposed; in addition, morphological descriptions for all taxa included in this study are provided. The results indicate that the shape of the seeds was constant within species, contrary to the characters that describe individual cell features, which showed important variation even within the same seed sample. In particular, the outline of the cells and the curvature of the anticlinal cell walls (ACW) were very variable, so a combination of character states was needed to describe the overall diversity of a sample. Conversely, the relief of the periclinal cell walls (PCW) was relatively constant throughout the seeds of the same species, but the relief of the cells of the lateral and peripheral faces was dissimilar in a number of taxa. In addition, other studies provide evidence that the relief of the PCW may vary in widely distributed species. Increased taxon sampling and multiple samples of species with wide geographical ranges will facilitate the study of patterns of variation, and may provide insights into the role of environmental variables on seed diversity of Portulacaceae.

scholarly journals Rheological, Mechanical and Morphological Characterization of Fillers in the Nautical Field: The Role of Dispersing Agents on Composite Materials

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1339 ◽  
Author(s):  
Silvia Vita ◽  
Rico Ricotti ◽  
Andrea Dodero ◽  
Silvia Vicini ◽  
Per Borchardt ◽  
...  
Keyword(s):  
External Surface ◽  
Morphological Characterization ◽  
Point Of View ◽  
Morphological Properties ◽  
Filler Materials ◽  
Efficient Tool ◽  
Hollow Glass Microspheres ◽  
Dispersing Agents

Coatings have a fundamental role in covering the external surface of yachts by acting both as protective and aesthetic layers. In particular, fillers represent the essential layer from the point of view of mechanical properties and consist of a polymeric matrix, different extenders and additives, and dispersing agents, with the latter having the role to provide good extender-matrix compatibility. In the present work, the effects of dispersing agents with an ionic or steric action on the interactions between hollow glass microspheres and an epoxy-polyamide resin are evaluated. Un-crosslinked filler materials are studied via rheological tests, whereas the mechanical and morphological properties of the crosslinked samples are assessed. The results clearly indicate that steric dispersing agents provide a much greater compatibility effect compared to ionic ones, owing to their steric hindrance capability, thus leading to better-performing filler materials with a less-marked Payne effect, which is here proved to be an efficient tool to provide information concerning the extent of component interactions in nautical fillers. To the best of our knowledge, this work represents the first attempt to deeply understand the role of dispersing agents, which are until now empirically used in the preparation of fillers.

Structural and Morphological Characterization of 3C-SiC Films Grown on (111), (211) and (100) Silicon Substrates

2008 ◽  
Vol 600-603 ◽  
pp. 231-234 ◽  
Author(s):  
Marc Portail ◽  
M. Nemoz ◽  
Marcin Zielinski ◽  
Thierry Chassagne
Keyword(s):  
Flow Rate ◽  
Morphological Characterization ◽  
Crystalline Quality ◽  
Silicon Substrates ◽  
Interfacial Defects ◽  
Twin Defects ◽  
Sic Films

The structural and morphological modifications induced by the carbonization stage upon 3C-SiC heteroepitaxial films grown on (111) and (100) oriented silicon substrates have been investigated. The crystalline quality of the films is strongly dependent on the carbonization parameters (propane flow rate and duration of carbonization). The (111) heteroepitaxial films coalesce more rapidly and present a lower dependence on the carbonization conditions than (100) films. By comparing the evolution of the interfacial defects (voids) density with existing models, we show that this is related to the initial mechanisms occurring during the carbonization stage. The twin defects densities on (111), (100) and (211) films are also investigated and the role of the only carbonization stage on their formation is studied.

scholarly journals 96-25: Role of 3D Rotational Angiography in the morphological characterization of the left atrial appendage aimed at closure interventions

EP Europace ◽  
2016 ◽  
Vol 18 (suppl_1) ◽  
pp. i66-i66
Author(s):  
Adolfo Fontenla ◽  
Iñaki Romero ◽  
Sagrario Fernandez-Casares ◽  
Belen Diaz ◽  
Felipe Hernandez ◽  
...  
Keyword(s):  
Left Atrial ◽  
Left Atrial Appendage ◽  
Morphological Characterization ◽  
Atrial Appendage ◽  
Rotational Angiography ◽  
3D Rotational Angiography

scholarly journals Morphological Characterization of Deciduous Enamel and Dentin in Patients Affected by Osteogenesis Imperfecta

2020 ◽  
Vol 10 (21) ◽  
pp. 7835
Author(s):  
Uros Josic ◽  
Tatjana Maravic ◽  
Maurizio Bossù ◽  
Milena Cadenaro ◽  
Allegra Comba ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Osteogenesis Imperfecta ◽  
Ultrastructural Level ◽  
Morphological Characterization ◽  
Deciduous Teeth ◽  
Tem Analysis ◽  
Correlative Analysis ◽  
Transmission Electron ◽  
Dentin Collagen

The purpose of this study was to clarify the structural and ultrastructural alterations of the enamel and dentin collagen network in the deciduous teeth of children affected by osteogenesis imperfecta (OI) using field-emission in-lens scanning electron microscopy (FEI-SEM) and transmission electron microscopy (TEM) analyses. Exfoliated primary teeth were collected from children with a diagnosis of OI and from healthy individuals (N = 24). Tooth slices containing both dentin and enamel were fixed, dehydrated and dried, gold sputtered, and observed using FEI-SEM. Additional dentin fragments were decalcified, dehydrated, embedded in resin, cut, and processed for TEM analysis. Under FEI-SEM, the enamel in OI-affected children showed an irregular prism distribution with the enamel hydroxyapatite crystals unpacked. Ultrastructural correlative analysis of the dentin in patients affected by OI showed an altered collagen pattern with a low density. In some areas, teeth in OI patients showed a reduction in the number of dentinal tubules, with odontoblastic process missing in most of the tubules. The presence of altered dentine and enamel organization in OI children was firmly established at an ultrastructural level, but additional biochemical studies are necessary in order to clarify quantitatively and qualitatively the collagenic and non-collagenic proteins in this disorder.

Morphological Characterization of Mycobacteriophage R1

1974 ◽  
Vol 32 ◽  
pp. 254-255
Author(s):  
B. L. Soloff ◽  
T. A. Rado
Keyword(s):  
Carbon Source ◽  
Stationary Phase ◽  
Growth Phase ◽  
Minimal Medium ◽  
Morphological Characterization ◽  
Logarithmic Growth Phase ◽  
Complete Lysis ◽  
Lysogenic Culture ◽  
Logarithmic Growth

Mycobacteriophage R1 was originally isolated from a lysogenic culture of M. butyricum. The virus was propagated on a leucine-requiring derivative of M. smegmatis, 607 leu−, isolated by nitrosoguanidine mutagenesis of typestrain ATCC 607. Growth was accomplished in a minimal medium containing glycerol and glucose as carbon source and enriched by the addition of 80 μg/ ml L-leucine. Bacteria in early logarithmic growth phase were infected with virus at a multiplicity of 5, and incubated with aeration for 8 hours. The partially lysed suspension was diluted 1:10 in growth medium and incubated for a further 8 hours. This permitted stationary phase cells to re-enter logarithmic growth and resulted in complete lysis of the culture.

Digital x-ray mapping of nanometer-size supported bimetallic catalysts

1988 ◽  
Vol 46 ◽  
pp. 530-531
Author(s):  
L. T. Germinario
Keyword(s):  
Background Radiation ◽  
Metal Cluster ◽  
Single Element ◽  
Beam Diameter ◽  
X Rays ◽  
X Ray ◽  
Major Interest ◽  
Induced Changes

Understanding the role of metal cluster composition in determining catalytic selectivity and activity is of major interest in heterogeneous catalysis. The electron microscope is well established as a powerful tool for ultrastructural and compositional characterization of support and catalyst. Because the spatial resolution of x-ray microanalysis is defined by the smallest beam diameter into which the required number of electrons can be focused, the dedicated STEM with FEG is the instrument of choice. The main sources of errors in energy dispersive x-ray analysis (EDS) are: (1) beam-induced changes in specimen composition, (2) specimen drift, (3) instrumental factors which produce background radiation, and (4) basic statistical limitations which result in the detection of a finite number of x-ray photons. Digital beam techniques have been described for supported single-element metal clusters with spatial resolutions of about 10 nm. However, the detection of spurious characteristic x-rays away from catalyst particles produced images requiring several image processing steps.

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