scholarly journals Preparation of Liposomes from Soy Lecithin Using Liquefied Dimethyl Ether

Foods ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1789
Author(s):  
Hideki Kanda ◽  
Tsubasa Katsube ◽  
Wahyudiono ◽  
Motonobu Goto
Keyword(s):  
Dimethyl Ether ◽  
Warm Water ◽  
Dialysis Membrane ◽  
Soy Lecithin ◽  
Ζ Potential ◽  
Transmission Electron ◽  
Ethanol Addition ◽  
Liposome Dispersion ◽  
Membrane Treatment ◽  
Conventional Medium

We investigated a method to prepare liposomes; soy lecithin was dissolved in liquefied dimethyl ether (DME) at 0.56 MPa, which was then injected into warm water. Liposomes can be successfully prepared at warm water temperatures above 45 °C. The transmission electron microscopy (TEM) images of the obtained liposomes, size distribution, ζ-potential measurements by dynamic light scattering and the amount of residual medium were compared by gas chromatography using the conventional medium, diethyl ether. The size of the obtained liposomes was approximately 60–300 nm and the ζ-potential was approximately −57 mV, which was almost the same as that of the conventional medium. Additionally, for the conventional media, a large amount remained in the liposome dispersion even after removal by depressurization and dialysis membrane treatment; however, liquefied DME, owing to its considerably low boiling point, was completely removed by depressurization. Liquefied DME is a very attractive medium for the preparation of liposomes because it does not have the toxicity and residue problems of conventional solvents or the hazards of ethanol addition and high pressure of supercritical carbon dioxide; it is also environmentally friendly.

Ultrastructure of conidia and conidium germination in the plant pathogenic fungus Alternaria cassiae

1997 ◽  
Vol 75 (2) ◽  
pp. 252-260 ◽  
Author(s):  
C. W. Mims ◽  
M. A. Rogers ◽  
C. G. Van Dyke
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Germ Tube ◽  
Pathogenic Fungus ◽  
Freeze Substitution ◽  
Dialysis Membrane ◽  
Common Mode ◽  
Plant Pathogenic Fungus ◽  
Transmission Electron ◽  
Germ Tubes

Transmission electron microscopy of plunge-frozen and freeze-substituted samples was used to examine germinating conidia of Alternaria cassiae, a plant pathogenic fungus used as a biological control agent for sicklepod (Cassia obtusifolia). Hydrated conidia on small pieces of dialysis membrane were incubated for 1, 2, or 3 h on the surface of corn meal agar prior to fixation. Conidia were large, darkly pigmented, and surrounded by a thick, two-layered wall. Each conidium was divided by transverse and longitudinal septa into multiple cells, a few of which sometimes appeared necrotic. Each septum tapered to a small central pore region with which Woronin bodies were associated. Each healthy cell of a conidium contained a typical complement of cellular organelles including multiple nuclei. With the exception of lipid bodies, all the various organelles were well preserved by plunge freezing and freeze substitution. Evidence of germ tube development was visible by 2 h post-incubation and well-developed germ tubes were present by 3 h. Two modes of germ tube development were observed. In the less common mode germ tubes developed inside conidia and grew internally through one or more adjacent cells before emerging from the conidium surface. Cells penetrated by internal germ tubes appeared necrotic. In the more common mode of germination, germ tubes developed directly from the conidium surface. Multiple germ tubes usually arose from each conidium and grew out in all directions. Germ tubes that contacted the underlying dialysis membrane continued to grow along its surface. Extracellular material was produced in association with developing germ tubes and coated the sides of germinated conidia and covered germ tubes growing along membranes. Key words: transmission electron microscopy, cryofixation, freeze substitution, germ tube development.

Dispersion Stability of Ni Nanoparticles in Ethanol with Poly (1-Vinyl-2-Pyrrolidone)

2006 ◽  
Vol 510-511 ◽  
pp. 206-209 ◽  
Author(s):  
Eun Hee Lee ◽  
Min Ku Lee ◽  
Chang Kyu Rhee
Keyword(s):  
Electron Microscopy ◽  
Visual Inspection ◽  
Negative Charge ◽  
Positive Charge ◽  
Ni Nanoparticles ◽  
Ζ Potential ◽  
Weight Percentage ◽  
Potential Value ◽  
Transmission Electron ◽  
The Stability

The stability of nanosized Ni dispersions with varying concentrations of poly (1-vinyl-2- pyrrolidone) (PVP) was investigated by means of a visual inspection, transmission profile measured by Turbiscan, zeta potential, and transmission electron microscopy. For dispersions with PVP, the ζ potential values varied from positive charge to negative charge. For dispersion with a 0.04 weight percentage of PVP, the ζ potential value showed 31.71 mV, which was the highest value, and the flocculation of Ni nanoparticles was not observed. Stable dispersions of Ni nanoparticles were produced by electrostatic, steric interactions, and the formation of bridging aggregation.

scholarly journals Liposomal Encapsulation of Carvacrol to Obtain Active Poly (Vinyl Alcohol) Films

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1589
Author(s):  
Johana Andrade ◽  
Chelo González-Martínez ◽  
Amparo Chiralt
Keyword(s):  
Vinyl Alcohol ◽  
Food Packaging ◽  
Film Formation ◽  
Membrane Lipid ◽  
Poly Vinyl Alcohol ◽  
Soy Lecithin ◽  
Ζ Potential ◽  
Polymeric Solutions ◽  
The Stability ◽  
Different Origins

Lecithins of different origins and compositions were used for the liposomal encapsulation of carvacrol within the framework of the development of active films for food packaging. Liposomes were incorporated into aqueous polymeric solutions from fully (F) and partially (P) hydrolysed Poly (vinyl alcohol) (PVA) to obtain the films by casting. The particle size distribution and ζ-potential of the liposomal suspensions, as well as their stability over time, were evaluated. Liposomal stability during film formation was analysed through the carvacrol retention in the dried film and the film microstructure. Subtle variations in the size distributions of liposomes from different lecithins were observed. However, the absolute values of the ζ-potential were higher (−52, −57 mV) for soy lecithin (SL) liposomes, followed by those of soy lecithin enriched with phosphatidylcholine (SL-PC) (−43, −50 mV) and sunflower lecithin (SFL) (−33, −38 mV). No significant changes in the liposomal properties were observed during the study period. Lyotropic mesomorphism of lipid associations and carvacrol leakage occurred to differing extents during the film drying step, depending on the membrane lipid composition and surface charge. Liposomes obtained with SL-PC were the most effective at maintaining the stability of carvacrol emulsion during film formation, which led to the greatest carvacrol retention in the films, whereas SFL gave rise to the least stable system and the highest carvacrol losses. P-PVA was less sensitive to the emulsion destabilisation due to its greater bonding capacity with carvacrol. Therefore, P-PVA with carvacrol-loaded SL-PC liposomes has great potential to produce active films for food packaging applications.

scholarly journals Stability of a Bifunctional Cu-Based Core@Zeolite Shell Catalyst for Dimethyl Ether Synthesis Under Redox Conditions Studied by Environmental Transmission Electron Microscopy andIn SituX-Ray Ptychography

2017 ◽  
Vol 23 (3) ◽  
pp. 501-512 ◽  
Author(s):  
Sina Baier ◽  
Christian D. Damsgaard ◽  
Michael Klumpp ◽  
Juliane Reinhardt ◽  
Thomas Sheppard ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Dimethyl Ether ◽  
Core Shell ◽  
X Ray ◽  
Environmental Transmission ◽  
The Core ◽  
Transmission Electron ◽  
The Stability

AbstractWhen using bifunctional core@shell catalysts, the stability of both the shell and core–shell interface is crucial for catalytic applications. In the present study, we elucidate the stability of a CuO/ZnO/Al2O3@ZSM-5 core@shell material, used for one-stage synthesis of dimethyl ether from synthesis gas. The catalyst stability was studied in a hierarchical manner by complementary environmental transmission electron microscopy (ETEM), scanning electron microscopy (SEM) andin situhard X-ray ptychography with a specially designedin situcell. Both reductive activation and reoxidation were applied. The core–shell interface was found to be stable during reducing and oxidizing treatment at 250°C as observed by ETEM andin situX-ray ptychography, although strong changes occurred in the core on a 10 nm scale due to the reduction of copper oxide to metallic copper particles. At 350°C,in situX-ray ptychography indicated the occurrence of structural changes also on theµm scale, i.e. the core material and parts of the shell undergo restructuring. Nevertheless, the crucial core–shell interface required for full bifunctionality appeared to remain stable. This study demonstrates the potential of these correlativein situmicroscopy techniques for hierarchically designed catalysts.

scholarly journals Magnetite-gaize composite stabilized with polyacrylic acid

2020 ◽  
pp. 12-17
Author(s):  
Gulnarkhan Kurmangazhy ◽  
Sagdat Tazhibayeva ◽  
Kuanyshbek Musabekov ◽  
Sandugash Sydykbayeva ◽  
Bibol Zhakipbaev
Keyword(s):  
Methylene Blue ◽  
Polyacrylic Acid ◽  
Ph Value ◽  
Anionic Polymer ◽  
Ζ Potential ◽  
Transmission Electron ◽  
Magnetite Particles ◽  
Surface Active ◽  
Oxygen Oxidation ◽  
Physical And Chemical

The surface-active substances stabilization are used to prevent aggregation of magnetite sorbents in the solvent, to protect against oxygen oxidation in the air as well as to combine several components with their specific properties in one material. In this work, the Elmore method synthesized a composite of magnetite-gaize stabilized with polyelectrolyte - anionic polymer polyacrylic acid. The stabilized gaize-magnetite composite is considered by physical and chemical methods. When studying a stabilized magnetite-gaize composite using transmission electron microscopy, a change in the size of magnetite particles in the structure of a clay space with a molding form is observed. Stabilization with polyacrylic acid reduces the value of the ζ-potential of composites from -18.5 mV to -19.9 mV. The effect of medium pH on the potential work of the magnetite-gaizecomposite and stabilized composite was observed. Increasing of the pH value leads to decreasing of the ζ-potential of gaize-magnetite composite from 4.2 mV to -32.6 mV and from 11.9 mV to -35.5 mV in the cause of stabilized composite. The effect of the stabilization of the composite on the adsorption was characterized using methylene blue was observed. Processing of adsorption by Langmuir and Freundlichmodels shows the effectiveness of stabilization. The maximum adsorption of methylene blue by Langmuir is 152.73 mg/g. The Freundlich constant 1/n shows that there is high compatibility between the adsorbat and the adsorbent.

Vegetative incompatibility in diploid isolates of Armillaria North American biological species I and V

1989 ◽  
Vol 67 (10) ◽  
pp. 3083-3089 ◽  
Author(s):  
K. I. Mallett ◽  
A. A. Hopkin ◽  
P. V. Blenis
Keyword(s):  
Contact Zone ◽  
North American ◽  
Biological Species ◽  
The Other ◽  
Interspecific Crosses ◽  
Dialysis Membrane ◽  
Vegetative Incompatibility ◽  
Transmission Electron ◽  
Armillaria Root Rot ◽  
Agar Media

Vegetative incompatibility among diploid isolates of Armillaria root rot pathogens (Armillaria spp.) was studied using isolates of North American biological species I (Armillaria ostoyae (Romagn.) Herink) and V (Armillaria sinapina Bérubé & Dessureault). Interspecific, intraspecific, and self crosses were made on dialysis membrane over malt agar media and on wood strips and wood blocks. Hyphal interactions were studied using light microscopy and scanning and transmission electron microscopy. On dialysis membrane, hyphae in the contact zone between the two species, the so-called "black line," were melanized and failed to fluoresce with fluorescein diacetate but stained with 3,3′-diaminobenzidine and L-β-3,4-dihydroxy-phenylalanine, indicating peroxidase and polyphenoloxidase activity in the contact zone. Hyphae adjacent to the contact zone fluoresced and did not show any significant reaction to the other stains. The hyphae of the contact zone in intraspecific crosses and self crosses were not melanized, fluoresced, and did not react with the other stains. No black lines were formed in the interspecific crosses made on or in wood. In both interspecific and intraspecific crosses, pseudosclerotial plates formed between the opposing mycelia. No pseudosclerotial plates were formed in the wood between opposing mycelia of self crosses. Results indicated that the interspecific and intraspecific reactions differ significantly and should be considered as separate and distinct phenomena.

Influence of Cell Wall Composition on the Fossilisation of Bacteria and the Implications for the Search for Early Life Forms

1997 ◽  
Vol 161 ◽  
pp. 491-504 ◽  
Author(s):  
Frances Westall
Keyword(s):  
Cell Wall ◽  
Life Forms ◽  
Cation Binding ◽  
Positive Bacterium ◽  
Gram Positive ◽  
Gram Positive Bacteria ◽  
Transmission Electron ◽  
Hydrothermal Sediments ◽  
Identification Of Bacteria ◽  
The Difference

AbstractThe oldest cell-like structures on Earth are preserved in silicified lagoonal, shallow sea or hydrothermal sediments, such as some Archean formations in Western Australia and South Africa. Previous studies concentrated on the search for organic fossils in Archean rocks. Observations of silicified bacteria (as silica minerals) are scarce for both the Precambrian and the Phanerozoic, but reports of mineral bacteria finds, in general, are increasing. The problems associated with the identification of authentic fossil bacteria and, if possible, closer identification of bacteria type can, in part, be overcome by experimental fossilisation studies. These have shown that not all bacteria fossilise in the same way and, indeed, some seem to be very resistent to fossilisation. This paper deals with a transmission electron microscope investigation of the silicification of four species of bacteria commonly found in the environment. The Gram positiveBacillus laterosporusand its spore produced a robust, durable crust upon silicification, whereas the Gram negativePseudomonas fluorescens, Ps. vesicularis, andPs. acidovoranspresented delicately preserved walls. The greater amount of peptidoglycan, containing abundant metal cation binding sites, in the cell wall of the Gram positive bacterium, probably accounts for the difference in the mode of fossilisation. The Gram positive bacteria are, therefore, probably most likely to be preserved in the terrestrial and extraterrestrial rock record.

A Reproducible Selective Stain for Cardiac Sarcoplasmic Reticulum

1974 ◽  
Vol 32 ◽  
pp. 214-215
Author(s):  
R. A. Waugh ◽  
J. R. Sommer
Keyword(s):  
Complex System ◽  
Electron Microscope ◽  
Sarcoplasmic Reticulum ◽  
Transmission Electron Microscope ◽  
Electron Microscopic ◽  
Cardiac Sarcoplasmic Reticulum ◽  
Transmission Electron

Cardiac sarcoplasmic reticulum (SR) is a complex system of intracellular tubules that, due to their small size and juxtaposition to such electron-dense structures as mitochondria and myofibrils, are often inconspicuous in conventionally prepared electron microscopic material. This study reports a method with which the SR is selectively “stained” which facilitates visualizationwith the transmission electron microscope.

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

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