scholarly journals Twisting of Fibers Balancing the Gel–Sol Transition in Cellulose Aqueous Suspensions

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 873 ◽  
Author(s):  
Dmitry Zlenko ◽  
Sergey Nikolsky ◽  
Alexander Vedenkin ◽  
Galina Politenkova ◽  
Aleksey Skoblin ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Cellulose Fibers ◽  
Film Production ◽  
3D Scaffold ◽  
Friction Forces ◽  
Practical Applications ◽  
Exponential Increase ◽  
The Individual ◽  
Scanning Electron

Cellulose hydrogels and films are advantageous materials that are applied in modern industry and medicine. Cellulose hydrogels have a stable scaffold and never form films upon drying, while viscous cellulose hydrosols are liquids that could be used for film production. So, stabilizing either a gel or sol state in cellulose suspensions is a worthwhile challenge, significant for the practical applications. However, there is no theory describing the cellulose fibers’ behavior and processes underlying cellulose-gel-scaffold stabilizing. In this work, we provide a phenomenological mechanism explaining the transition between the stable-gel and shapeless-sol states in a cellulose suspension. We suppose that cellulose macromolecules and nanofibrils under strong dispersing treatment (such as sonication) partially untwist and dissociate, and then reassemble in a 3D scaffold having the individual elements twisted in the nodes. The latter leads to an exponential increase in friction forces between the fibers and to the corresponding fastening of the scaffold. We confirm our theory by the data on the circular dichroism of the cellulose suspensions, as well as by the direct scanning electron microscope (SEM) observations and theoretical assessments.

Resolution and measurement in the scanning electron microscope

1987 ◽  
Vol 45 ◽  
pp. 534-537 ◽  
Author(s):  
Michael T. Postek
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Engineering Design ◽  
Resolving Power ◽  
Practical Applications ◽  
Instrument Resolution ◽  
Accurate Definition ◽  
Definition Of ◽  
Scanning Electron ◽  
Better Than

The term ultimate resolution or resolving power is the very best performance that can be obtained from a scanning electron microscope (SEM) given the optimum instrumental conditions and sample. However, as it relates to SEM users, the conventional definitions of this figure are ambiguous. The numbers quoted for the resolution of an instrument are not only theoretically derived, but are also verified through the direct measurement of images on micrographs. However, the samples commonly used for this purpose are specifically optimized for the measurement of instrument resolution and are most often not typical of the sample used in practical applications.SEM RESOLUTION. Some instruments resolve better than others either due to engineering design or other reasons. There is no definitively accurate definition of how to quantify instrument resolution and its measurement in the SEM.

The Determination and Application of the Point Spread Function in the Scanning Electron Microscope

2018 ◽  
Vol 24 (4) ◽  
pp. 396-405 ◽  
Author(s):  
Matthew D. Zotta ◽  
Mandy C. Nevins ◽  
Richard K. Hailstone ◽  
Eric Lifshin
Keyword(s):  
Spatial Distribution ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Beam Current ◽  
Beam Shape ◽  
Practical Applications ◽  
Energy Beam ◽  
Working Distance ◽  
Scanning Electron

AbstractA method is presented to determine the spatial distribution of electrons in the focused beam of a scanning electron microscope (SEM). Knowledge of the electron distribution is valuable for characterizing and monitoring SEM performance, as well as for modeling and simulation in computational scanning electron microscopy. Specifically, it can be used to characterize astigmatism as well as study the relationship between beam energy, beam current, working distance, and beam shape and size. In addition, knowledge of the distribution of electrons in the beam can be utilized with deconvolution methods to improve the resolution and quality of backscattered, secondary, and transmitted electron images obtained with thermionic, FEG, or Schottky source instruments. The proposed method represents an improvement over previous methods for determining the spatial distribution of electrons in an SEM beam. Several practical applications are presented.

Spot Electron-Beam Lithography as a Novel Method of High Resolution Pattern Nanofabrication

2014 ◽  
Vol 215 ◽  
pp. 459-461
Author(s):  
Alexander S. Samardak ◽  
Margarita V. Anisimova ◽  
Alexey V. Ognev ◽  
Vadim Yu. Samardak ◽  
Liudmila A. Chebotkevich
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
High Resolution ◽  
Scanning Electron Microscope ◽  
Electron Beam Lithography ◽  
The Novel ◽  
Practical Applications ◽  
Novel Method ◽  
20 Nm ◽  
Scanning Electron

We present a novel method of pattern nanofabrication with high resolution and small shape defects using the traditional electron-beam lithography (EBL) or only a scanning electron microscope (SEM). Our method of Spot EBL is extremely fast, highly scalable on big areas, capable of sub-20 nm resolution and fabrication of polymer patterns with complicated shapes. We show the nanostructure images fabricated by Spot EBL and propose practical applications of the novel method.

scholarly journals Preparation and Characterization of Chitosan/Agar Blended Films: Part 1. Chemical Structure and Morphology

2012 ◽  
Vol 9 (3) ◽  
pp. 1431-1439 ◽  
Author(s):  
Esam A. El-hefian ◽  
Mohamed Mahmoud Nasef ◽  
Abdul Hamid Yahaya
Keyword(s):  
Fourier Transform ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Smooth Surface ◽  
Chemical Structure ◽  
Structure And Morphology ◽  
The Individual ◽  
Main Component ◽  
Scanning Electron

Chitosan/agar (CS/AG) films were prepared by blending different proportions of chitosan and agar (considering chitosan as the main component) in solution forms. The chemical structure and the morphology of the obtained blended films were investigated using Fourier transform infrared (FTIR) and field emission scanning electron microscope (FESEM). It was revealed that chitosan and agar form a highly compatible blend and their films displayed homogenous and smooth surface properties compared to the individual pure components.

scholarly journals SEM imaging and XPS characterization of doped PVDF fibers

2021 ◽  
Vol 270 ◽  
pp. 01011
Author(s):  
Tereza Smejkalová ◽  
Ştefan Ţălu ◽  
Rashid Dallaev ◽  
Klára Částková ◽  
Dinara Sobola ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Photoelectron Spectroscopy ◽  
Analytical Methods ◽  
Polyvinylidene Fluoride ◽  
X Ray ◽  
Xps Characterization ◽  
Good Biocompatibility ◽  
The Individual ◽  
Scanning Electron

Polyvinylidene fluoride (PVDF) is one of the most promising electroactive polymers; it exhibits excellent electroactive behaviours, good biocompatibility, excellent chemical resistance, and thermal stability, rendering it an attractive material for biomedical, electronic, environmental and energy harvesting applications. This work aims to further improve its properties by the inclusion of powders of piezoactive materials. Polyvinylidene fluoride was formed by electrospinning into fibres with a thickness of 1.5-0.3 µm and then examined in a scanning electron microscope. The work offers a description of the current procedure in the preparation of samples and their modification for examination in a scanning electron microscope, characterizes the individual components of doped fibres and deals with specific instruments used for various analytical methods. The work contains a theoretical introduction to the analytical methods to which the samples will be further subjected, such as energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS). The obtained excellent properties of doped PVDF could be used in the design of sensors.

The spores of Dryopteris clintoniana and its relatives

1972 ◽  
Vol 50 (10) ◽  
pp. 2027-2029 ◽  
Author(s):  
D. M. Britton
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Diploid Species ◽  
Ancestral Species ◽  
The Individual ◽  
Scanning Electron

The perispore morphology of two diploid species, Dryopteris goldiana (Hook.) A. Gray and D. ludoviciana (Kunze) Small; two allotetraploids, D. celsa (Palmer) Small and D. cristata (L.) A. Gray; and the allohexaploid D. clintoniana (D. C. Eaton) Dowell, was examined with the scanning electron microscope. The contributions of the individual genomes of each species as shown by the morphology of the perine were shown, and an attempt was made to extrapolate the contribution to perine phenotype of genome B from an unknown ancestral species B.

Novel Method for Controlled Wetting of Materials in the Environmental Scanning Electron Microscope

2013 ◽  
Vol 19 (1) ◽  
pp. 30-37 ◽  
Author(s):  
Anna Jansson ◽  
Alexandra Nafari ◽  
Anke Sanz-Velasco ◽  
Krister Svensson ◽  
Stefan Gustafsson ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Environmental Scanning Electron Microscopy ◽  
Water Reservoir ◽  
Cellulose Fibers ◽  
Environmental Scanning Electron Microscope ◽  
Environmental Scanning ◽  
Wetting Properties ◽  
Novel Method ◽  
Scanning Electron

AbstractEnvironmental scanning electron microscopy has been extensively used for studying the wetting properties of different materials. For some types of investigation, however, the traditional ways of conducting in situ dynamic wetting experiments do not offer sufficient control over the wetting process. Here, we present a novel method for controlled wetting of materials in the environmental scanning electron microscope (ESEM). It offers improved control of the point of interaction between the water and the specimen and renders it more accessible for imaging. It also enables the study of water transport through a material by direct imaging. The method is based on the use of a piezo-driven nanomanipulator to bring a specimen in contact with a water reservoir in the ESEM chamber. The water reservoir is established by local condensation on a Peltier-cooled surface. A fixture was designed to make the experimental setup compatible with the standard Peltier cooling stage of the microscope. The developed technique was successfully applied to individual cellulose fibers, and the absorption and transport of water by individual cellulose fibers were imaged.

scholarly journals Manipulation of nanoparticles of different shapes inside a scanning electron microscope

2014 ◽  
Vol 5 ◽  
pp. 133-140 ◽  
Author(s):  
Boris Polyakov ◽  
Sergei Vlassov ◽  
Leonid M Dorogin ◽  
Jelena Butikova ◽  
Mikk Antsov ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Tuning Fork ◽  
Quartz Tuning Fork ◽  
Static Friction ◽  
Si Substrate ◽  
Friction Forces ◽  
Different Shapes ◽  
Particle Geometry ◽  
Scanning Electron

In this work polyhedron-like gold and sphere-like silver nanoparticles (NPs) were manipulated on an oxidized Si substrate to study the dependence of the static friction and the contact area on the particle geometry. Measurements were performed inside a scanning electron microscope (SEM) that was equipped with a high-precision XYZ-nanomanipulator. To register the occurring forces a quartz tuning fork (QTF) with a glued sharp probe was used. Contact areas and static friction forces were calculated by using different models and compared with the experimentally measured force. The effect of NP morphology on the nanoscale friction is discussed.

Scanning electron microscopy of the sporosorus in Polymyxa betae (Plasmodiophoromycetes)

1988 ◽  
Vol 66 (12) ◽  
pp. 2518-2522 ◽  
Author(s):  
G. Clafardini ◽  
B. Marotta
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Direct Contact ◽  
Host Cells ◽  
Polymyxa Betae ◽  
Resting Spores ◽  
The Individual ◽  
Scanning Electron

Results are reported for observations of sporosori of Polymyxa betae Keskin made with the scanning electron microscope on sugar-beet roots. Sporosori were extracted from the host cells 15, 20, and 30 days after inoculation, purified, and observed with the scanning electron microscope. The morphology of sporosori differs, depending on their stage of maturation. Immature resting spores (cysts) are polyhedral and characterized by a wall rich in folds that converge towards the upper portion in six ridges arranged regularly in a spoke fashion. During maturation the walls of the individual resting spores unfold and come into direct contact with each other. Towards the end of maturation the resting spores become rounded and, after their walls split, germination takes place. After germination the sporosori still conserve their structure as a result of the effect of a cementing substance that keeps the walls united. Details are given of the system used to extract and purify the sporosori for observation using the scanning electron microscope.

The Alteration of the Pore Spaces in Sandstones

1973 ◽  
Vol 31 ◽  
pp. 210-211
Author(s):  
R. E. Ferrell ◽  
G. G. Paulson
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
The Other ◽  
Coarse Grained ◽  
Depositional Fabric ◽  
Soluble Components ◽  
Scanning Electron ◽  
Shape And Size

The pore spaces in sandstones are the result of the original depositional fabric and the degree of post-depositional alteration that the rock has experienced. The largest pore volumes are present in coarse-grained, well-sorted materials with high sphericity. The chief mechanisms which alter the shape and size of the pores are precipitation of cementing agents and the dissolution of soluble components. Each process may operate alone or in combination with the other, or there may be several generations of cementation and solution.The scanning electron microscope has ‘been used in this study to reveal the morphology of the pore spaces in a variety of moderate porosity, orthoquartzites.

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