scholarly journals Early Cretaceous striate tricolpate pollen from the Borehole Mersa Matruh 1, North West Desert, Egypt

1988 ◽  
Vol 7 (2) ◽  
pp. 201-215 ◽  
Author(s):  
James H. J. Penny
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
New Taxa ◽  
Early Cretaceous ◽  
North West ◽  
Sem Study ◽  
Stratigraphic Ranges ◽  
Scanning Electron

Abstract. Striate tricolpate pollen has been recovered from Early Cretaceous samples of the borehole Mersa Matruh 1 in the N.W. Desert of Egypt. Scanning Electron Microscope (SEM) study has revealed fine details of their exine scupture, on the basis of which four new taxa, STRIOTRI-OVAL, STRIOTRI-SMOOTHMUR, STRIOTRI-SEGMUR and STRIORET-SMOOTH, are distinguished. The stratigraphic ranges of these are discussed and they are compared with other published species. They are among the oldest striate tricolpate pollen yet described, appearing in sediments of Early Aptian age, slightly predating the first reliable records of reticulate tricolpates in the sequence studied. The lack of earlier reticulate grains is attributed to possible sample failure. There is evidence that the true first appearance of tricoplate pollen in Egypt may be late Barrenian.

Neogene occurrences of the marine acritarch genusNannobarbophoraHabib and Knapp, 1982 emend., and the new speciesN. Gedlii

2003 ◽  
Vol 77 (2) ◽  
pp. 382-385 ◽  
Author(s):  
Martin J. Head
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
North Atlantic ◽  
Diagnostic Feature ◽  
Sem Study ◽  
Scanning Electron

The stratigraphic utility of small marine acritarchs in the Neogene has been known for more than a decade (e.g., de Vernal and Mudie, 1989). Their potential for biostratigraphy in the Cretaceous is also well known, and was elegantly elucidated by Habib and Knapp (1982) in a detailed scanning electron microscope (SEM) study from the western North Atlantic. Habib and Knapp erected 12 new acritarch genera including the acanthomorph genusNannobarbophoraand its three speciesN. barbata(the name of the type),N. pistilla, andN. platforma. A diagnostic feature ofNannobarbophorais the presence of spinules concentrated on, or restricted to, the surface of distally closed processes. Excystment is by a simple linear split (Habib and Knapp, 1982, p. 347).

Scanning Electron Microscopic Study of the Eggs of the Warthog Louse (Haematopinus Phacochoeri)

1997 ◽  
Vol 3 (S2) ◽  
pp. 113-114
Author(s):  
C. Baker ◽  
E.D. Green
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Environmental Changes ◽  
General Structure ◽  
Electron Microscopic ◽  
Razor Blade ◽  
Scanning Electron Microscopic Study ◽  
Sem Study ◽  
Scanning Electron Microscopic ◽  
Scanning Electron

The large eggs of Haematopinus phacochoeri are found attached to the long dorsal mane bristles of the diurnal warthog. The eggs are generally exposed to great environmental stresses such as excessive sunlight and temperature as well as the occasional plunge under water or mud during grooming. This investigation was therefore undertaken to determine how the eggs of H. phococoeri are adapted to tolerate the various environmental changes it is constantly exposed to. To our knowledge no other SEM study on the eggs of this species has been performed.Specimens still attached to the bristles were fixed in 70% ethanol, dehydrated and ultrasonically cleaned. Some eggs were longitudinally sectioned with a razor blade to expose the chorionic layers. The eggs were critical point dried in liquid CO2, mounted and viewed by means of a Leica Stereoscan 420 scanning electron microscope.The general structure of the shell consists of two layers of chorion, i.e. the endo-and exochorion. These two layers are attached at the pre-formed line of weakness at the operculum and again near the hydropyle. Elsewhere these two layers are completely separated by the respiratory layer.

Lacuneolimna gen. nov., Lacuneolimna zalokariae comb. nov. and Lacuneolimna novagallia spec. nov. (Bacillariophyceae) from the French Guiana diatom freshwater flora

Phytotaxa ◽  
2015 ◽  
Vol 231 (1) ◽  
pp. 19 ◽  
Author(s):  
Loïc Tudesque ◽  
René Le Cohu ◽  
Michel Coste ◽  
Horst Lange-Bertalot
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
New Taxa ◽  
French Guiana ◽  
New Genus ◽  
Freshwater Diatoms ◽  
Diatom Genus ◽  
Scanning Electron

The freshwater diatoms of the French Guiana have received little attention so far. A new diatom genus, Lacuneolimna, based on the species Eolimna zalokariae, is described from a small rainforest stream. Numerous ultrastructural features differ from the genus Eolimna, notably the pluriseriate striae lying between relief-like elevated virgae and depressed externally. In addition, another species new to science, L. novagallia, belonging to this new genus, was discovered in the same place. Detailed light and scanning electron microscope observations are used to characterize the morphology and the ultrastructure of these two new taxa.

scholarly journals Perfection of unused Ni-Ti endodontic files, myth or reality? A scanning electron microscope (SEM) study

2015 ◽  
Vol 7 (2) ◽  
pp. 16-21 ◽  
Author(s):  
AbuMostafa Ammar ◽  
AlOmari Mohammed ◽  
AlQashtini Ihsan ◽  
AlAbdullah Nuha AlJabr Sara ◽  
Domia Reham
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Sem Study ◽  
Scanning Electron

scholarly journals Archaeopyle variability in Early Cretaceous dinocysts of the partiform gonyaulacoid genus <i>Druggidium</i> Habib

1986 ◽  
Vol 5 (2) ◽  
pp. 17-26 ◽  
Author(s):  
Ian C. Harding
Keyword(s):  
Electron Microscope ◽  
New Species ◽  
Scanning Electron Microscope ◽  
Early Cretaceous ◽  
Taxonomic Significance ◽  
One New Species ◽  
Scanning Electron

Abstract. Scanning electron microscope (S.E.M.) observation techniques have enabled paratabulation formulae to be elucidated (in both Kofoidian and Taylor-Evitt notation) for the partiform gonyaulacoid dinocyst genus Druggidium Habib. Archaeopyle variability within the species of this genus is highlighted, further emphasising the uncertainties concerning the taxonomic significance of archaeopyle type. The genus Druggidium is therefore emended, as is the species D. jubatum Duxbury. One new species, D. augustum, is described.

Three new araphid diatoms (Bacillariophyta) from the Maritime Antarctic Region

Phytotaxa ◽  
2014 ◽  
Vol 167 (3) ◽  
pp. 256 ◽  
Author(s):  
BART VAN DE VIJVER ◽  
EDUARDO A. MORALES ◽  
KATEŘINA KOPALOVÁ
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
New Taxa ◽  
Maritime Antarctic ◽  
Antarctic Region ◽  
Diatom Flora ◽  
Ecological Preferences ◽  
The Antarctic ◽  
Scanning Electron

A revision of taxa from the genus Staurosira and Staurosirella from the Maritime Antarctic Region, formerly identified as Staurosirella (Fragilaria) pinnata and Fragilaria alpestris, resulted in the description of three new taxa: Staurosira pottiezii Van de Vijver sp. nov., Staurosirella antarctica Van de Vijver & E.Morales sp. nov. and S. frigida Van de Vijver & E.Morales sp. nov. Detailed light (LM) and scanning electron microscope (SEM) observations are used to better characterize the morphology and ultrastructure of these three new taxa. Comparisons with similar taxa and the ecological preferences of each species are added. The revision of these species confirmed the endemic nature of the Antarctic diatom flora. 

scholarly journals Evaluation of Effectiveness of Cleaning of Root Canals using Protaper and K3 Rotary Systems: A SEM Study

2015 ◽  
Vol 6 (1) ◽  
pp. 20-25
Author(s):  
K Shashikala ◽  
BS Keshava Prasad ◽  
Anukriti Tyagi
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Smear Layer ◽  
Root Canals ◽  
Significant Difference ◽  
Sem Study ◽  
Group A ◽  
Group B ◽  
Scanning Electron

ABSTRACT The aim of this in vitro study was to compare the debris and smear layer removal following root canal preparation using two different rotary systems with scanning electron microscope (SEM). The rotary systems used were Protaper and K3. Forty single rooted permanent mandibular premolars were chosen for the study. They were assigned two groups on the basis of instrumentation used. The teeth were sectioned at the level of cementoenamel junction and instrumented with Protaper in group A and with K3 in group B. The root canals were thoroughly irrigated with 5 ml of 2.5 % NaOCl during instrumentation. After instrumentation, 5 ml of normal saline was used as a final rinse. The teeth were split longitudinally and the specimens were prepared for SEM evaluation. Scanning electron microscope photomicrographs showed presence of debris and smear layer. The SEM photomicrographs were scored, based on the standard score rating system, and the scores were tabulated accordingly. The scores obtained from the specimens were subjected to statistical analysis. Results showed opening of dentinal tubules and effective removal of smear layer in group A (Protaper) and no significant difference between both the groups (groups A and B) regarding debris. How to cite this article Tyagi A, Prasad BSK, Shashikala K. Evaluation of Effectiveness of Cleaning of Root Canals using Protaper and K3 Rotary Systems: A Sem Study. World J Dent 2015;6(1):20-25.

SEM study on gastrulation; internal structure at the stage of ventral blastoporal groove in bufo arenarum

1978 ◽  
Vol 36 (2) ◽  
pp. 552-553
Author(s):  
Jorge Herkovits
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Internal Structure ◽  
Sagittal Plane ◽  
Cell Types ◽  
Vitelline Membrane ◽  
Present Communication ◽  
Sem Study ◽  
Bufo Arenarum ◽  
Scanning Electron

SEM studies on amphibian gastrulation have shown the overall shape and arrangement of several cell types (e. g. bottle cells, mesodermal cells, ectodermal cells, etc. ) as well as the cellular activities in the blastocoel cavity during archenteron floor descent. The main purpose of the present communication is to show the internal structure of Bufo arenarum gastrula as viewed in sagittal dissection at the stage when the ventral blastoporal groove starts forming.Material and Methods: Bufo arenarum gastrula were fixed in 2, 5% glutaraldehyde in phosphate buffer for 2, 5 hrs. After removing the vitelline membrane the embryos were fractured and then dissected near the mid-sagittal plane. The specimens were dehydrated through an acetone series, dried according to the critical point technique, coated with evaporated gold-platinum and observed in a Jeol JSM-U3 scanning electron microscope operated at 5-15 kW.Observations: The internal structure of a Bufo arenarum gastrula at the ventral blastoporal groove stage is illustrated in Fig. 1. Blastocoel cavity (B), internal endodermal yolky cells (Y), prospective ectoderm (PE), archenteron (A), dorsal blastoporal lip (L), ventral blastoporal groove (V).

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