Morphological characterization of Oscillatoriales (Cyanobacteria) from Ross Island and southern Victoria Land, Antarctica

1991 ◽  
Vol 3 (1) ◽  
pp. 35-45 ◽  
Author(s):  
Paul A. Broady ◽  
Andrew L. Kibblewhite
Keyword(s):  
Ross Sea ◽  
Apical Cell ◽  
Morphological Characterization ◽  
Cross Sectional ◽  
Victoria Land ◽  
Terrestrial Habitats ◽  
Width Distribution ◽  
Morphology And Morphometry ◽  
Sectional Shape

Field populations of Oscillatoriales, from fresh and saline lakes and ponds, and from terrestrial habitats, are characterised on the basis of their morphology and morphometry. Fifteen morphotypes are recognized principally from the following characteristics; cross-sectional shape of the trichome, presence or absence of a calyptra on the apical cell, occurrence or otherwise of numerous trichomes within a common sheath, and trichome width distribution. Where possible morphotypes are assigned to traditional species described by earlier investigations of algae in the Ross Sea region and a reassessment is made of the early descriptions, in some cases using material from the identical locations to the original collections. The following traditional species are described; Lyngbya murrayi, Microcoleus vaginatus, Oscillatoria deflexa, O. koettlitzi, O. priestleyi, O. sancta, Phormidium autumnale and P. subproboscidea. Intraspecific morphotypes of M. vaginatus, O. priestleyi and P. autumnale are recognised on the basis of trichome width. A new species and variety of Crinalium (Crow) Winder, Stal & Mur, a genus characterized by flattened trichomes, are described from cryoconite ponds on glaciers. C. glaciale sp. nov. possesses wide, straight trichomes in contrast to C. glaciale var. helicoides nov. var. in which trichomes are narrower and helically coiled.

scholarly journals Characterization of Protistan Assemblages in the Ross Sea, Antarctica, by Denaturing Gradient Gel Electrophoresis

2004 ◽  
Vol 70 (4) ◽  
pp. 2028-2037 ◽  
Author(s):  
Rebecca J. Gast ◽  
Mark R. Dennett ◽  
David A. Caron
Keyword(s):  
Species Composition ◽  
Gel Electrophoresis ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Ross Sea ◽  
Morphological Characterization ◽  
Culture Independent ◽  
Gradient Gel Electrophoresis ◽  
Ice Floes ◽  
Protistan Species

ABSTRACT The diversity of protistan assemblages has traditionally been studied using microscopy and morphological characterization, but these methods are often inadequate for ecological studies of these communities because most small protists inherently lack adequate taxonomic characters to facilitate their identification at the species level and many protistan species also do not preserve well. We have therefore used a culture-independent approach (denaturing gradient gel electrophoresis [DGGE]) to obtain an assessment of the genetic composition and distribution of protists within different microhabitats (seawater, meltwater or slush on sea-ice floes, and ice) of the Ross Sea, Antarctica. Samples of the same type (e.g., water) shared more of the same bands than samples of different types (e.g., ice versus water), despite being collected from different sites. These findings imply that samples from the same environment have a similar protistan species composition and that the type of microenvironment significantly influences the protistan species composition of these Antarctic assemblages. It should be noted that a large number of bands among the samples within each microhabitat were distinct, indicating the potential presence of significant genetic diversity within each microenvironment. Sequence analysis of selected DGGE bands revealed sequences that represent diatoms, dinoflagellates, ciliates, flagellates, and several unidentified eukaryotes.

Analysis of reinforcement efficiency and microscopic characterization of glass and carbon roving geometry in prestressed concrete composites

2021 ◽  
pp. 002199832110133
Author(s):  
Richard Haas ◽  
Till Quadflieg ◽  
Oleg Stolyarov
Keyword(s):  
Prestressed Concrete ◽  
Ct Scanning ◽  
Bending Test ◽  
Flexural Properties ◽  
Cross Sectional ◽  
Four Point Bending ◽  
Reinforcement Efficiency ◽  
The Cross ◽  
Sectional Shape

In this work, the reinforcement efficiency of concrete composites prestressed with glass and carbon rovings was studied. Prestressed concrete composites samples were prepared at a prestress level one-third the maximum tensile strength of the roving. The flexural properties of the manufactured composites were determined using a four-point bending test. Additionally, changes in the cross-sectional shape of the reinforcing rovings in the initial and prestressed states were analyzed using CT scanning and optical microscopy. The results showed that prestressing significantly affected the flexural properties of the concrete composites. Thus, the limit of proportionality increased by 1.26 and 1.85 for a composite reinforced with glass and carbon roving, respectively. The maximum flexural strength increased by approximately 1.2 times for both reinforcing rovings. The change in the cross-sectional shape of the reinforcing roving during prestressing enhances the efficiency of prestressed concrete composites.

scholarly journals Faithful Scanning Electron Microscopic (SEM) visualization of 3D printed alginate-based scaffolds

2020 ◽  
Author(s):  
Marcus Koch ◽  
Małgorzata K. Włodarczyk-Biegun
Keyword(s):  
High Water ◽  
Morphological Characterization ◽  
High Water Content ◽  
Electron Microscopic ◽  
Cross Sectional ◽  
3D Architecture ◽  
3D Printed ◽  
Preparation Techniques ◽  
Scanning Electron

AbstractThe morphological characterization of 3D printed hydrogel-based scaffolds is essential for monitoring their size, shape, surface texture and internal structure. Among other microscopic techniques, Scanning Electron Microscopy (SEM) is capable of visualizing nearly all kinds of materials at different length scales, with exceptional precision, if investigation under vacuum is possible. However, due to the high water content of hydrogel-based scaffolds and the connected volume change after drying, special preparation techniques are necessary to stabilize the 3D architecture when imaged by SEM. Here we present a straightforward cryo-SEM technique to visualize 3D printed hydrogel-based alginate scaffolds. By use of a homemade cryo-SEM holder and plunge-freezing in liquid ethane, scaffolds are visualized from the top and cross-sectional view at different magnifications. The proposed method is compared with SEM imaging in different modes (cyro-SEM, conventional SEM, ESEM) following other commonly used sample preparation techniques, such as plunging in liquid nitrogen, air-drying, freeze-drying and plunging in liquid ethane after graded dehydration. These approaches, except ESEM, lead to shrinkage, deformation, distortion or disintegration of the scaffolds and consequently give rise to artifacts in imaging. The presented results indicate that cryo-SEM after plunging in liquid ethane allows for the most faithful and time-efficient visualization of 3D printed alginate scaffolds.

Development of multifunctional different cross-sectional shaped coaxial composite filaments for SMART textile applications

2016 ◽  
Vol 87 (16) ◽  
pp. 1991-2004 ◽  
Author(s):  
Ali Afzal ◽  
Jean-Yves Drean ◽  
Omar Harzallah ◽  
Nabyl Khenoussi ◽  
Sheraz Ahmad ◽  
...  
Keyword(s):  
Pure Copper ◽  
Resin Matrix ◽  
Design Parameters ◽  
Cross Sectional ◽  
Smart Textile ◽  
The Cross ◽  
Sectional Surface ◽  
Poly Ethylene ◽  
Sectional Shape

The aim of this study is to design a spinneret that can be used efficiently for the manufacturing of coaxial composite filaments. Poly(ethylene terephthalate) was used as resin matrix with 99.9% pure copper filament as the core. The characterization of the polymer was done to determine polymer thermal and rheological properties. Multi-shaped coaxial composite filaments were obtained after successful laboratory-scale melt extrusion machine modification and spinneret development. The cross-sectional surface and shape were analyzed with a scanning electron microscope. Coaxial filaments having the cross-section including elliptical, triangular, rectangular and circular shapes were developed. The characterization of spinneret design and coaxial composite filaments were also reported. The effect of spinneret design parameters on the cross-sectional shape of the filament were analyzed.

Prevalence of Minor Larynx Structural Alterations: Influence on the Concept of a Normal Vocal Fold

2018 ◽  
Vol 160 (2) ◽  
pp. 295-301 ◽  
Author(s):  
Bruno Teixeira Moraes ◽  
Noemi Grigoletto De Biase
Keyword(s):  
Vocal Fold ◽  
Medical Center ◽  
Upper Airway ◽  
Morphological Characterization ◽  
Cross Sectional ◽  
Structural Alterations ◽  
Sulcus Vocalis ◽  
Common Combination ◽  
Fold Cover

Objective To determine the prevalence of minor structural alterations (MSA) in the vocal fold cover in a population submitted to extralaryngeal site surgery and to characterize them according to morphological and epidemiological parameters. Study Design This was a cross-sectional and observational study. Setting Tertiary referral medical center. Subjects and Methods A total of 147 patients underwent general anesthesia for extralaryngeal site surgery indicated for a procedure extraneous to the study and irrespective of the presence of vocal complaint. Next, detection and morphological characterization of MSAs in the vocal fold cover were performed by means of suspension microlaryngoscopy with laryngeal inspection and palpation without surgical intervention related to this procedure. The laryngeal findings were compared with variables from a clinical and demographic characteristics questionnaire given to these individuals. Results A 21.1% prevalence of MSAs was identified in the sample, which included a majority of individuals without vocal complaint (95.9%). Of these, 5.4% of individuals had laryngeal microdiaphragms, 16.3% sulcus vocalis, and 4.1% epidermoid cysts. No pouch sulcus or mucosal bridges were found. The identification of these alterations occurred mainly after 10 years of age, without effects of sex, vocal abuse, or upper airway conditions. The most common combination of MSAs was bilateral sulcus vocalis. Conclusions The prevalence of MSAs in laryngeal coverage in this predominantly vocally asymptomatic population was 21.1%, with identification of sulcus vocalis, epidermoid cyst, and laryngeal microdiaphragm. Age was the only clinical or demographic characteristic associated with these alterations.

scholarly journals Performance characterization of multifunctional different cross-sectional-shaped coaxial composite filaments for SMART textile applications

2018 ◽  
Vol 48 (6) ◽  
pp. 1059-1080 ◽  
Author(s):  
Ali Afzal ◽  
Omar Harzallah ◽  
Jean-Yves Drean ◽  
Niaz-Ahmad Akhtar ◽  
Sheraz Ahmad
Keyword(s):  
Mechanical Properties ◽  
Mechanical Performance ◽  
Design Parameters ◽  
Sensors And Actuators ◽  
Cross Sectional ◽  
Smart Textile ◽  
Sectional Shape ◽  
Applied Stresses ◽  
Metal Polymer

The aim of this study is to investigate the effect of spinneret design parameters on cross-sectional shape and mechanical performance characteristics of coaxial composite filaments. A number of different cross-sectional-shaped metal/polymer core/sheath coaxial composite filaments were developed by changing spinneret design parameters. The cross-sectional shapes obtained were circular, rectangular, triangular and elliptical shapes. The mechanical performance of filaments was evaluated for application in sensors and actuators. The change of cross-sectional shape significantly influences mechanical properties of developed filaments which express their vulnerability during applied stresses in their life cycle.

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.

Microstructural characterization of CoPtCr/Cr thin film disks by cross-section TEM and elongated probe micro-diffraction

1991 ◽  
Vol 49 ◽  
pp. 762-763
Author(s):  
M.A. Parker ◽  
K.E. Johnson ◽  
C. Hwang ◽  
A. Bermea
Keyword(s):  
Magnetic Recording ◽  
Electron Probe ◽  
Microstructural Characterization ◽  
Crystallographic Structure ◽  
Recording Media ◽  
Layer By Layer ◽  
Cross Sectional ◽  
New Techniques ◽  
Polished Side

We have reported the dependence of the magnetic and recording properties of CoPtCr recording media on the thickness of the Cr underlayer. It was inferred from XRD data that grain-to-grain epitaxy of the Cr with the CoPtCr was responsible for the interaction observed between these layers. However, no cross-sectional TEM (XTEM) work was performed to confirm this inference. In this paper, we report the application of new techniques for preparing XTEM specimens from actual magnetic recording disks, and for layer-by-layer micro-diffraction with an electron probe elongated parallel to the surface of the deposited structure which elucidate the effect of the crystallographic structure of the Cr on that of the CoPtCr.XTEM specimens were prepared from magnetic recording disks by modifying a technique used to prepare semiconductor specimens. After 3mm disks were prepared per the standard XTEM procedure, these disks were then lapped using a tripod polishing device. A grid with a single 1mmx2mm hole was then glued with M-bond 610 to the polished side of the disk.

TEM characterization of silicon epitaxial layer grown on Si-TaS2, eutectic composites

1991 ◽  
Vol 49 ◽  
pp. 802-803
Author(s):  
C.M. Sung ◽  
M. Levinson ◽  
M. Tabasky ◽  
K. Ostreicher ◽  
B.M. Ditchek
Keyword(s):  
Substrate Surface ◽  
Bulk Sample ◽  
Surface Cleaning ◽  
Native Oxide ◽  
Czochralski Growth ◽  
Ion Milling ◽  
Cross Sectional ◽  
Cleaning Methods ◽  
Field Emission Cathodes

Directionally solidified Si/TaSi2 eutectic composites for the development of electronic devices (e.g. photodiodes and field-emission cathodes) were made using a Czochralski growth technique. High quality epitaxial growth of silicon on the eutectic composite substrates requires a clean silicon substrate surface prior to the growth process. Hence a preepitaxial surface cleaning step is highly desirable. The purpose of this paper is to investigate the effect of surface cleaning methods on the epilayer/substrate interface and the characterization of silicon epilayers grown on Si/TaSi2 substrates by TEM.Wafers were cut normal to the <111> growth axis of the silicon matrix from an approximately 1 cm diameter Si/TaSi2 composite boule. Four pre-treatments were employed to remove native oxide and other contaminants: 1) No treatment, 2) HF only; 3) HC1 only; and 4) both HF and HCl. The cross-sectional specimens for TEM study were prepared by cutting the bulk sample into sheets perpendicular to the TaSi2 fiber axes. The material was then prepared in the usual manner to produce samples having a thickness of 10μm. The final step was ion milling in Ar+ until breakthrough occurred. The TEM samples were then analyzed at 120 keV using the Philips EM400T.

Characterization of Rh/Si multilayer structure by HREM and HAADF

1992 ◽  
Vol 50 (1) ◽  
pp. 122-123
Author(s):  
Y. Cheng ◽  
J. Liu ◽  
M.B. Stearns ◽  
D.G. Steams
Keyword(s):  
Normal Incidence ◽  
High Resolution Electron Microscopy ◽  
X Rays ◽  
Beam Direction ◽  
Cross Sectional ◽  
Optical Elements ◽  
Resolution Electron ◽  
Point To Point ◽  
Better Than

The Rh/Si multilayer (ML) thin films are promising optical elements for soft x-rays since they have a calculated normal incidence reflectivity of ∼60% at a x-ray wavelength of ∼13 nm. However, a reflectivity of only 28% has been attained to date for ML fabricated by dc magnetron sputtering. In order to determine the cause of this degraded reflectivity the microstructure of this ML was examined on cross-sectional specimens with two high-resolution electron microscopy (HREM and HAADF) techniques.Cross-sectional specimens were made from an as-prepared ML sample and from the same ML annealed at 298 °C for 1 and 100 hours. The specimens were imaged using a JEM-4000EX TEM operating at 400 kV with a point-to-point resolution of better than 0.17 nm. The specimens were viewed along Si [110] projection of the substrate, with the (001) Si surface plane parallel to the beam direction.

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