Topotactic replacement of augite by omphacite in a blueschist rock from north-west Turkey

1978 ◽  
Vol 42 (324) ◽  
pp. 435-438 ◽  
Author(s):  
M. A. Carpenter ◽  
A. Okay
Keyword(s):  
Fluid Phase ◽  
Partial Replacement ◽  
Cation Ordering ◽  
North West ◽  
Space Groups ◽  
Transmission Electron ◽  
Ordering Schemes ◽  
Antiphase Domains ◽  
The Relationship ◽  
Symmetry Change

SummaryPartial replacement of original igneous augite crystals by omphacite during blueschist metamorphism of a dolerite from the Mihalliççik area of north-west Turkey has been studied by transmission electron microscopy. The replacement occurred topotactically, apparently by ion exchange with a fluid phase, which left the basic pyroxene structure unchanged. Cation ordering in the omphacite caused a symmetry change fromC-face centred to primitive with the formation of fine-scale antiphase domains. Selected-area diffraction provides evidence forP2andP2/cspace groups for the ordered omphacite though the best ordered areas show a tendency towardsP2/n(reflections violating then-glide are very weak) and also contain fine, wavy, disordered precipitates approximately parallel to (too).It is suggested that the replacement temperature was below the cation-ordering temperature and that the omphacite grew in a metastable, disordered state. Subsequent ordering occurred under irreversible conditions via a series of intermediate structures. The ordering sequence may illustrate the relationship between different ordering schemes in other blueschist pyroxenes.

Transmission Electron Microscopy study of Bi-based superconducting phases

1990 ◽  
Vol 48 (4) ◽  
pp. 50-51
Author(s):  
J.G. Wen ◽  
K.K. Fung
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Single Crystals ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Space Groups ◽  
Superconducting Phases ◽  
Ceramic Samples ◽  
Transmission Electron ◽  
Modulated Structures

Bi-based superconducting phases have been found to be members of a structural series represented by Bi2Sr2Can−1Cun−1On+4, n=1,2,3, and are referred to as 2201, 2212, 2223 phases. All these phases are incommensurate modulated structures. The super space groups are P2/b, NBbmb 2201, 2212 phases respectively. Pb-doped ceramic samples and single crystals and Y-doped single crystals have been studied by transmission electron microscopy.Modulated structures of all Bi-based superconducting phases are in b-c plane, therefore, it is the best way to determine modulated structure and c parameter in diffraction pattern. FIG. 1,2,3 show diffraction patterns of three kinds of modulations in Pb-doped ceramic samples. Energy dispersive X-ray analysis (EDAX) confirms the presence of Pb in the three modulated structures. Parameters c are 3 0.06, 38.29, 30.24Å, ie 2212, 2223, 2212 phases for FIG. 1,2,3 respectively. Their average space groups are all Bbmb.

K-MEANS CLUSTERING ALGORITHM BASED CLASSIFICATION OF SOIL FERTILITY IN NORTH WEST NIGERIA

2020 ◽  
Vol 4 (2) ◽  
pp. 780-787
Author(s):  
Ibrahim Hassan Hayatu ◽  
Abdullahi Mohammed ◽  
Barroon Ahmad Isma’eel ◽  
Sahabi Yusuf Ali
Keyword(s):  
Soil Fertility ◽  
Crop Yield ◽  
Clustering Algorithm ◽  
Soil Samples ◽  
North West ◽  
R Programming ◽  
Available Information ◽  
Northwest Region ◽  
The Relationship

Soil fertility determines a plant's development process that guarantees food sufficiency and the security of lives and properties through bumper harvests. The fertility of soil varies according to regions, thereby determining the type of crops to be planted. However, there is no repository or any source of information about the fertility of the soil in any region in Nigeria especially the Northwest of the country. The only available information is soil samples with their attributes which gives little or no information to the average farmer. This has affected crop yield in all the regions, more particularly the Northwest region, thus resulting in lower food production.  Therefore, this study is aimed at classifying soil data based on their fertility in the Northwest region of Nigeria using R programming. Data were obtained from the department of soil science from Ahmadu Bello University, Zaria. The data contain 400 soil samples containing 13 attributes. The relationship between soil attributes was observed based on the data. K-means clustering algorithm was employed in analyzing soil fertility clusters. Four clusters were identified with cluster 1 having the highest fertility, followed by 2 and the fertility decreases with an increasing number of clusters. The identification of the most fertile clusters will guide farmers on where best to concentrate on when planting their crops in order to improve productivity and crop yield.

A Religious State (A Study of Hasyim Asyari and Muhammad Iqbal's Thought on the Relation of Religion, State and Nationalism)

2020 ◽  
Vol 3 (2) ◽  
pp. 226
Author(s):  
Arik Dwijayanto ◽  
Yusmicha Ulya Afif
Keyword(s):  
Intellectual History ◽  
British Empire ◽  
Political Identity ◽  
British Imperialism ◽  
Early Generation ◽  
North West ◽  
The North ◽  
Religion And State ◽  
The Relationship ◽  
Diverse Cultures

<p><em>This article explores the concept of a religious state proposed by two Muslim leaders: Hasyim Asyari (1871-1947), an Indonesian Muslim leader and Muhammad Iqbal (1873-1938), an Indian Muslim leader. Both of them represented the early generation when the emerging revolution for the independence of Indonesia (1945) from the Dutch colonialism and India-Pakistan (1947) from the British Imperialism. In doing so, they argued that the religious state is compatible with the plural nation that has diverse cultures, faiths, and ethnicities. They also argued that Islam as religion should involve the establishment of a nation-state. But under certain circumstances, they changed their thinking. Hasyim changed his thought that Islam in Indonesia should not be dominated by a single religion and state ideology. Hasyim regarded religiosity in Indonesia as vital in nation-building within a multi-religious society. While Iqbal changed from Indian loyalist to Islamist loyalist after he studied and lived in the West. The desire of Iqbal to establish the own state for the Indian Muslims separated from Hindus was first promulgated in 1930 when he was a President of the Muslim League. Iqbal expressed the hope of seeing Punjab, the North West province, Sind and Balukhistan being one in a single state, having self-government outside the British empire. In particular, the two Muslim leaders used religious legitimacy to establish political identity. By using historical approach (intellectual history), the relationship between religion, state, and nationalism based on the thinking of the two Muslim leaders can be concluded that Hasyim Asyari more prioritizes Islam as the ethical value to build state ideology and nationalism otherwise Muhammad Iqbal tends to make Islam as the main principle in establishment of state ideology and nationalism.</em></p><em>Keywords: Hasyim Asyari, Muhammad Iqbal, religion, state, nationalism.</em>

scholarly journals A complicated quasicrystal approximant ∊16 predicted by the strong-reflections approach

2010 ◽  
Vol 66 (1) ◽  
pp. 17-26 ◽  
Author(s):  
Mingrun Li ◽  
Junliang Sun ◽  
Peter Oleynikov ◽  
Sven Hovmöller ◽  
Xiaodong Zou ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Unit Cell ◽  
Space Groups ◽  
Inverse Fourier Transformation ◽  
Transmission Electron ◽  
Structure Factors ◽  
Precession Electron Diffraction ◽  
Density Map ◽  
Electron Density Map ◽  
Good Agreement

The structure of a complicated quasicrystal approximant ∊16 was predicted from a known and related quasicrystal approximant ∊6 by the strong-reflections approach. Electron-diffraction studies show that in reciprocal space, the positions of the strongest reflections and their intensity distributions are similar for both approximants. By applying the strong-reflections approach, the structure factors of ∊16 were deduced from those of the known ∊6 structure. Owing to the different space groups of the two structures, a shift of the phase origin had to be applied in order to obtain the phases of ∊16. An electron-density map of ∊16 was calculated by inverse Fourier transformation of the structure factors of the 256 strongest reflections. Similar to that of ∊6, the predicted structure of ∊16 contains eight layers in each unit cell, stacked along the b axis. Along the b axis, ∊16 is built by banana-shaped tiles and pentagonal tiles; this structure is confirmed by high-resolution transmission electron microscopy (HRTEM). The simulated precession electron-diffraction (PED) patterns from the structure model are in good agreement with the experimental ones. ∊16 with 153 unique atoms in the unit cell is the most complicated approximant structure ever solved or predicted.

scholarly journals Chemical Quantification of Atomic-Scale EDS Maps under Thin Specimen Conditions

2014 ◽  
Vol 20 (6) ◽  
pp. 1782-1790 ◽  
Author(s):  
Ping Lu ◽  
Eric Romero ◽  
Shinbuhm Lee ◽  
Judith L. MacManus-Driscoll ◽  
Quanxi Jia
Keyword(s):  
Atomic Scale ◽  
Specimen Thickness ◽  
Peak Width ◽  
Thin Specimen ◽  
Gaussian Peak ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
The Relationship ◽  
Chemical Quantification

AbstractWe report our effort to quantify atomic-scale chemical maps obtained by collecting energy-dispersive X-ray spectra (EDS) using scanning transmission electron microscopy (STEM) (STEM-EDS). With thin specimen conditions and localized EDS scattering potential, the X-ray counts from atomic columns can be properly counted by fitting Gaussian peaks at the atomic columns, and can then be used for site-by-site chemical quantification. The effects of specimen thickness and X-ray energy on the Gaussian peak width are investigated using SrTiO3 (STO) as a model specimen. The relationship between the peak width and spatial resolution of an EDS map is also studied. Furthermore, the method developed by this work is applied to study cation occupancy in a Sm-doped STO thin film and antiphase boundaries (APBs) present within the STO film. We find that Sm atoms occupy both Sr and Ti sites but preferably the Sr sites, and Sm atoms are relatively depleted at the APBs likely owing to the effect of strain.

Interfaces in Structural Ceramics

MRS Bulletin ◽  
1990 ◽  
Vol 15 (10) ◽  
pp. 51-59 ◽  
Author(s):  
M. Grant Norton ◽  
C. Barry Carter
Keyword(s):  
Structural Ceramics ◽  
Interface Engineering ◽  
Micro Structure ◽  
Complete Understanding ◽  
Intimate Contact ◽  
Transmission Electron ◽  
Processed Material ◽  
Wide Range ◽  
Alternative Materials ◽  
The Relationship

Structural ceramics are necessarily polycrystalline and their usefulness is largely determined by the interfaces between the grains. The relationship between the structure and chemistry of different interfaces and the micro-structure can be illustrated by reviewing studies of interfaces in a wide range of materials including such classical ceramics as Al2O3, the current “hightech” polyphase ceramics exemplified by ZrO2-toughened Al2O3, and the composite materials of the future. Using transmission electron microscopy is essential for a complete understanding, but limitations to its use must be recognized. Only by understanding the factors that control the behavior of these interfaces will it become possible to further extend the application of interface engineering.Structural ceramics are a group of materials that can be used for applications requiring their strength to persist at high temperatures or in conditions that would be particularly corrosive to alternative materials, which are usually metallic. Strength and strength-related properties such as toughness depend largely on the microstructural features of the processed material.The microstructure is defined by the morphology and size of the grains and the interfaces between these grains. If the grains are in intimate contact, then the interface is a grain boundary of the type familiar from studies of metals.

The relationship between emerging neural crest cells and basement membranes in the trunk of the mouse embryo: a TEM and immunocytochemical study

Development ◽  
1986 ◽  
Vol 98 (1) ◽  
pp. 251-268
Author(s):  
J. Sternberg ◽  
S. J. Kimber
Keyword(s):  
Neural Crest ◽  
Neural Tube ◽  
Cell Shape ◽  
Type Iv Collagen ◽  
Neural Crest Cell ◽  
Basement Membranes ◽  
Type Iv ◽  
Transmission Electron ◽  
The Relationship ◽  
Crest Cell

The earliest stage of neural crest cell (NCC) migration is characterized by an epitheliomesenchymal transformation, as the cells leave the neural tube. There is evidence that in a number of cell systems this transformation is accompanied by alteration or depletion of associated basement membranes. This study examines the ultrastructural relationship between mouse NCCs and adjacent basement membranes during the earliest stages of migration from the neural tube. Basement membranes were identified by transmission electron microscopy (TEM) and immunofluorescence using antibodies to type-IV collagen. The ultrastructural features of NCCs and their relationship with surrounding tissues were also examined using TEM. In the dorsal region of the neural tube, from which NCCs originate, the basement membrane was depleted or absent, and with the immunofluorescence technique it was shown that this pattern was reflected in a deficit of type-IV collagen. TEM observations indicated that ultrastructurally NCCs differ from their neuroepithelial neighbours only in overall cell shape and their relationship to other cells and the extracellular matrix.

A simple technique for staining of cell membranes with imidazole and osmium tetroxide.

1995 ◽  
Vol 43 (10) ◽  
pp. 1079-1084 ◽  
Author(s):  
G Thiéry ◽  
J Bernier ◽  
M Bergeron
Keyword(s):  
Osmium Tetroxide ◽  
Cell Membranes ◽  
Cell Organelles ◽  
Unsaturated Lipids ◽  
Transmission Electron ◽  
Glutaraldehyde Solution ◽  
Kidney Liver ◽  
The Relationship ◽  
Resin Penetration

We describe a simple new technique based on the affinity of imidazole and osmium tetroxide for unsaturated lipids. Organs (e.g., kidney, liver, intestine) were perfused in vivo with a glutaraldehyde solution. Tissue fragments were then immersed in a solution containing imidazole and OsO4 and are further stained with a double lead and copper citrate solution. Ultra-thin (0.06 microns) or thick (0.1-0.3 microns) sections were observed with transmission electron microscopy (80-100 kV). The method presented permits excellent visualization of cell membranes (e.g., endoplasmic reticulum, endocytotic apparatus) because it favors good resin penetration and the alkaline pH preserves cell volume. A better stereomicroscopic analysis of the relationship between cell organelles can be carried out with thick sections. The imidazole/osmium can be used routinely because the technical steps are easy and simple to follow. Furthermore, it can complement other cytochemical methods.

scholarly journals Microscopical characterization of the salivary glands of the carnivorous cephalaspidean Philinopsis depicta (Mollusca, Opisthobranchia)

2009 ◽  
Vol 15 (S3) ◽  
pp. 39-40
Author(s):  
A. Lobo-da-Cunha ◽  
I. Ferreira ◽  
G. Calado
Keyword(s):  
Salivary Glands ◽  
Secretory Cells ◽  
Apical Region ◽  
Ciliated Cells ◽  
Transmission Electron ◽  
Herbivorous Species ◽  
Small Clusters ◽  
The Relationship ◽  
Apical Vacuole

AbstractCephalaspideans are a group of opisthobranch gastropods comprising carnivorous and herbivorous species, allowing an investigation of the relationship between these diets and the morphofunctional features of the salivary glands.In this study, the salivary glands of the carnivorous cephalaspidean Philinopsis depicta were observed by light microscopy using semithin sections and by transmission electron microscopy. A central duct runs along the length of these thin ribbon-shaped glands dividing them in two halves, each formed by a single row of tubules perpendicularly attached to the central duct. The simple epithelium of the central duct and lateral tubes contains ciliated cells and two types of secretory cells, named granular cells and cells with apical vacuole (Fig. 1). A very thin outer layer of connective tissue covers the epithelium (Fig. 1). The ciliated cells are numerous but very thin, forming small clusters between secretory cells. The nucleus, several mitochondria and a few lysosomes are located in the apical region were the cells are wider. A very thin cytoplasmic stalk reaches the base of the epithelium and contains bundles of filaments in addition to some mitochondria.

scholarly journals Rock art and the prehistoric landscape of Galicia: the results of field survey 1992–1994

1995 ◽  
Vol 61 ◽  
pp. 347-370 ◽  
Author(s):  
Richard Bradley ◽  
Felipe Criado Boado ◽  
Ramón Fábregas Valcarce
Keyword(s):  
Bronze Age ◽  
Field Survey ◽  
Rock Art ◽  
Outer Edge ◽  
Early Bronze Age ◽  
Copper Age ◽  
North West ◽  
Abrupt Changes ◽  
Ground Conditions ◽  
The Relationship

This paper discusses the relationship between the earlier prehistoric pattern of settlement in Atlantic Europe and the creation of rock art. It investigates the organisation of the Copper Age and Early Bronze Age landscape of north-west Spain using the evidence provided by the distribution, siting, and composition of rock carvings. It presents the results of field survey in three sample areas extending from the centre to the outer edge of their distribution. Although these drawings cannot be interpreted as illustrations of daily life, they may have helped to define rights to particular resources in an area which experienced abrupt changes of ground conditions over the course of the year.

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