scholarly journals A Complex Assemblage of Crystal Habits of Pyrite in the Volcanic Hot Springs from Kamchatka, Russia: Implications for the Mineral Signature of Life on Mars

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 535 ◽  
Author(s):  
Min Tang ◽  
Yi-Liang Li
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Hot Springs ◽  
Morphological Features ◽  
Nutritional Elements ◽  
Wide Range ◽  
Life On Mars ◽  
Continuous Deposition ◽  
Microbial Mediation ◽  
Scanning Electron

In this study, the crystal habits of pyrite in the volcanic hot springs from Kamchatka, Russia were surveyed using scanning electron microscopy. Pyrite crystals occur either as single euhedral crystals or aggregates with a wide range of crystal sizes and morphological features. Single euhedral crystals, with their sizes ranging from ~200 nm to ~40 µm, exhibit combinations of cubic {100}, octahedral {111}, and pyritohedral {210} and {310} forms. Heterogeneous geochemical microenvironments and the bacterial activities in the long-lived hot springs have mediated the development and good preservation of the complex pyrite crystal habits: irregular, spherulitic, cubic, or octahedral crystals congregating with clay minerals, and nanocrystals attaching to the surface of larger pyrite crystals and other minerals. Spherulitic pyrite crystals are commonly covered by organic matter-rich thin films. The coexistence of various sizes and morphological features of those pyrite crystals indicates the results of secular interactions between the continuous supply of energy and nutritional elements by the hot springs and the microbial communities. We suggest that, instead of a single mineral with unique crystal habits, the continuous deposition of the same mineral with a complex set of crystal habits results from the ever-changing physicochemical conditions with contributions from microbial mediation.

Oospore dimensions and wall ornamentation in Chara braunii

Biologia ◽  
2008 ◽  
Vol 63 (4) ◽  
Author(s):  
Patrycja Boszke ◽  
Mariusz Pełechaty ◽  
Andrzej Pukacz
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Local Population ◽  
Polar Axis ◽  
Morphological Features ◽  
Cylindrical Shape ◽  
Reproductive Structures ◽  
Equatorial Diameter ◽  
Variable Character ◽  
Scanning Electron

AbstractMorphological features of oospores of a rarely noted species Chara braunii Gmel. were examined in a local population (fishpond near Tuplice village, Ziemia Lubuska region, mid-western Poland). The largest polar axis (LPA, length), largest equatorial diameter (LED, width), isopolarity index (ISI = LPA/LED* 100), and the number of ridges and width of fossa of 90 oospores were measured. Additionally, the oospore wall ornamentation pattern was examined by means of scanning electron microscopy (SEM). As a result, a cylindrical shape and the lack of so-called “shoulder” were found. Oospore length and width ranged between 466.8–600.1 µm and 250.1–366.7 µm, respectively, with the ISI index values between 148 and 213. The number of ridges was 8–10 and the width of fossa varied between 50.0 and 66.7 µm. The oospore width appeared to be the most changeable feature, whereas, by contrast, the number of ridges was the least variable character. Wall ornamentation can be described as tuberculate and a ribbon was present on the ridges. As a comparative material for the study performed, 9 oospores from Professor Izabela Dąmbska’s Collection of Charophytes of Poland were measured. It was evidenced that variation ranges of most of the features of Chara braunii oospores from Tuplice fishpond are similar to those of Professor Dąmbska’s herbarium materials and to data reported by authors from other countries as well. The morphology of reproductive structures does not follow the variation of thalli characteristics.

Delamination Behavior of Cu-Low-k Stack Under Different Slurries

2003 ◽  
Vol 767 ◽  
Author(s):  
A. K. Sikder ◽  
S. Thagella ◽  
P. B. Zantye ◽  
Ashok Kumar
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Chemical Mechanical Polishing ◽  
Wear Behavior ◽  
Polished Surface ◽  
Cu Metallization ◽  
Wide Range ◽  
Low K ◽  
Delamination Behavior ◽  
Scanning Electron

AbstractLower mechanical strength, reduced cohesive strength and lack of compatibility with other interconnect materials, are the major challenges involved in chemical mechanical polishing (CMP) of Cu metallization with ultra low-k materials as interlayer dielectrics. In this study we have investigated the polishing behavior of patterned Cu samples with underneath different low-k materials using two different slurries and a wide range of machine parameters. CMP micro tribometer was used to polish the samples with different rotations of platen (50 to 250 RPM) and down forces (1-6 PSI). Friction co-efficient and wear behavior were also investigated at different conditions. Optical and scanning electron microscopy was used to investigate the polished surface. It was observed that the two different Cu slurries used for polishing have marked effects on the polishing of Cu-low-k stack with respect to wear and delamination.

scholarly journals Dry Sliding Tribological Properties of a Hard Anodized AA6082 Aluminum Alloy

Metals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 207
Author(s):  
Eleonora Santecchia ◽  
Marcello Cabibbo ◽  
Abdel Magid Salem Hamouda ◽  
Farayi Musharavati ◽  
Anton Popelka ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Wear Behavior ◽  
Structure Characterization ◽  
Dry Sliding Wear ◽  
Dry Sliding ◽  
Alumina Layer ◽  
Wide Range ◽  
Wear Tests ◽  
Scanning Electron

The applications of aluminum and its alloys are still limited by low hardness and low wear resistance properties. Surface modifications, such anodizing and plasma electrolytic oxidation, represent a feasible way to overcome these drawbacks. In this study, discs of AA6082 were subjected to the so-called G.H.A. hard anodizing process leading to an anodized layer having a honeycomb-like structure. Samples having alumina layer thicknesses of 10, 50 and 100 μm were subjected to unidirectional dry sliding wear tests, using bearing steel and silicon nitride as counterbody materials. Surface and structure characterization of the samples were performed before and after the tribological tests, using a wide range of techniques; atomic force microscopy and scanning electron microscopy techniques were used before the wear tests. The wear scars were characterized by scanning electron microscopy, energy dispersive spectroscopy and Fourier transform infrared spectroscopy techniques. Results show that the different thickness of the anodized layer does not affect the pores dimensions but has an influence on the micrometric domains in which the pores are divided. These features coupled with the wear test conditions, show to have a strong influence on the wear behavior. The thinnest sample showed also the best performance against the ceramic counterbody.

New data on the morphology of Comephoronema oschmarini (Nematoda, Cystidicolidae), a little-known gastrointestinal parasite of Lota lota (Teleostei) in Palaearctic Eurasia

2007 ◽  
Vol 52 (2) ◽  
Author(s):  
František Moravec ◽  
Vladimíra Hanzelová ◽  
Daniel Gerdeaux
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Morphological Features ◽  
Valid Species ◽  
Lake Geneva ◽  
Gastrointestinal Parasite ◽  
Intensity Of Infection ◽  
Lota Lota ◽  
Scanning Electron

AbstractThe nematode Comephoronema oschmarini Trofimenko, 1974 (Cystidicolidae) was found in the stomach of the burbot Lota lota (Linnaeus) of Lake Geneva, Savoy, France, collected on 23 March 2000 [prevalence 60% (3/5); intensity of infection 2–66 (mean 35)]. This material made it possible to study in detail the morphology of this so far little-known parasite, using both light and scanning electron microscopy (the latter not previously used for this species). The SEM examination showed taxonomically important morphological features, not previously reported, including the presence of distinct terminal pseudolabial projections (protuberances), four submedian labia, four bilobed submedian sublabia, and only four cephalic papillae. Deirids were found to be bifurcated. A description of the true arrangement of the two last pairs of minute caudal papillae and phasmids in the male is given. Species of Compehoronema Layman, 1933 are considered to be closely related to those of Ascarophis van Beneden, 1871. A key to valid species of Comephoronema is provided.

Synthesis of Fe2O3/CNTs for the Fast Removal of Tetracycline from Aqueous Solutions

2014 ◽  
Vol 915-916 ◽  
pp. 933-941 ◽  
Author(s):  
Zhong Jie Zhang ◽  
Chang Yu Lu ◽  
Wei Huang ◽  
Wei Sheng Guan ◽  
Yue Xin Peng
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Magnetic Measurements ◽  
Ferrite Nanoparticles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Wide Range ◽  
Fast Removal ◽  
Scanning Electron

The effective remove to tetracycline still remains a big challenge for scientists. In this work, we used a new method for preparing functional magnetic CNTS with ferrite nanoparticles. A wide range of techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and magnetic measurements were applied to characterize the obtained Fe2O3/CNTs. Moreover, we have also studied the properties of adsorbent to tetracycline. In addition, we have found that the Fe2O3/CNTs are better reusable adsorbent than other traditional adsorbents by magnetic separation recycling method.

A re-description of Fragilaria fonticola Hustedt and its varieties, with three new combinations and one new species from India

Phytotaxa ◽  
2020 ◽  
Vol 453 (3) ◽  
pp. 179-198
Author(s):  
ANBUKKARASU VIGNESHWARAN ◽  
CARLOS E. WETZEL ◽  
DAVID M. WILLIAMS ◽  
BALASUBRAMANIAN KARTHICK
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
New Species ◽  
River Basin ◽  
Western Ghats ◽  
Morphological Features ◽  
New Combinations ◽  
One New Species ◽  
Scanning Electron

Tabularia (Kützing) D.M. Williams & Round has received some attention since its separation from Synedra. The present study investigates Fragilaria fonticola Hustedt and its varieties based on the analysis of the type materials. The combinations were proposed as Tabularia fonticola (Hustedt) C.E. Wetzel & D.M. Williams comb. nov. (≡ Fragilaria fonticola Hustedt), Tabularia angusta (Hustedt) C.E. Wetzel & D.M. Williams comb. nov. et stat. nov. (≡ Fragilaria fonticola var. angusta Hustedt), Tabularia chandolensis (Gandhi) A. Vigneshwaran, D.M. Williams & B. Karthick comb. nov. (≡ Synedra chandolensis Gandhi) and the new species, Tabularia koynensis sp. nov. is also described from the Koyna River basin, Western Ghats, India. The detailed morphological features were analysed under light and scanning electron microscopy. Tabularia koynensis has linear valves outline with square to rounded ends. Striae short, radiate towards ends. This new species compared with T. sinensis, T. fasciculata, T. tabulata, T. kobayasii and Fragilaria longissima, which differ in size, valve shape, striae density and ultrastructure.

Investigation of taxonomically important morphological features of endoparasitic bat flies of the subfamily Ascodipterinae (Diptera: Streblidae) by scanning electron microscopy

Zootaxa ◽  
2006 ◽  
Vol 1122 (1) ◽  
pp. 57 ◽  
Author(s):  
MICHAEL W. HASTRITER ◽  
KATHARINA DITTMAR ◽  
MICHAEL F. WHITING
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Light Microscopy ◽  
Morphological Features ◽  
Taxonomic Position ◽  
Old World ◽  
Bat Flies ◽  
Molecular Information ◽  
Scanning Electron

Endoparasitic dealate females of Ascodipteron and an undescribed genus of Ascodipterinae are examined by scanning electron microscopy. The unique morphology of the head and mouth parts and terminal segments are displayed and discussed. Prior reports have focused only on details observable with light microscopy. The taxonomic position of members of the subfamily Ascodipterinae relative to the Old World families of Streblidae and Nycteribiidae is briefly discussed in light of previously published molecular information.

scholarly journals Morphological features of the heart of six mosquito species as revealed by scanning electron microscopy

2011 ◽  
Vol 31 (1-2) ◽  
pp. 98-102 ◽  
Author(s):  
Gustavo Ferreira Martins ◽  
José Marcelo Ramalho-Ortigão ◽  
Paulo Filemon Paolucci Pimenta
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Mosquito Species ◽  
Morphological Features ◽  
Scanning Electron

Seed morphology of Epilobium and Chamaenerion (Onagraceae) in Turkey

Phytotaxa ◽  
2017 ◽  
Vol 331 (2) ◽  
pp. 169 ◽  
Author(s):  
KAMİL COŞKUNÇELEBİ ◽  
SERDAR MAKBUL ◽  
SEDA OKUR
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Seed Morphology ◽  
Morphological Features ◽  
Seed Shape ◽  
Generic Level ◽  
Specific Level ◽  
Periclinal Wall ◽  
First Time ◽  
Scanning Electron

Macro- and micro-morphological features of seeds belonging to 26 taxa from Turkey were observed under the light and scanning electron microscopy. Present findings partly agree with segregation of Epilobium and Chamerion at generic level. The members of the genus Epilobium were distinguished by seeds with conical, semispherical, cylindrical or crest-like papillae or without papillae, granulate periclinal surfaces, papillae with parallel, radial, irregular or spirally furrow and the members of Chamerion were distinguished by seeds crest-like papillae or without papillae and without granulate periclinal surfaces and without furrow. The results also showed that seed shape, presence/absence of papillae and beak, papillae shape and ornamentation, and periclinal wall features are valuable for delimiting the examined taxa specific level within both genera. A key to Turkish Epilobium and Chamerion taxa based on seed morphology is presented for the first time

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