scholarly journals Cratons Mark the Spot for Mineral Bonanzas

Eos ◽  
2020 ◽  
Vol 101 ◽  
Author(s):  
Bas den Hond
Keyword(s):  
Large Deposits

A new map of the thickness of Earth’s lithosphere contains clues to large deposits of key metals.

On Diatomaceous Deposits in Scotland

1884 ◽  
Vol 6 (28) ◽  
pp. 87-89 ◽  
Author(s):  
W. Ivison Macadam
Keyword(s):  
Short Paper ◽  
Limited Extent ◽  
Geological Society ◽  
White Substance ◽  
Large Deposits

Deposits of Diatoms have been long known to exist in Scotland, but such deposits have so far always been of limited extent. Specimens for the microscope have been readily obtained from certain localities, such as Peterhead, but the occurrence of large deposits covering great tracts of land was unknown.In the year 1881 my attention was directed, by Mr. Hamilton Bell, to a white substance he had obtained from the Peat of Aberdeenshire. During April, 1882, I read a short paper before the Edinburgh Geological Society in which I gave the analysis of a sample received from Mr. Bell, with particulars furnished by the Rev. Geo. Davidson, Minister of Logie Coldstone, Dinner, who also kindly furnished a list of the Diatomaceæ he had identified in the deposit. The list contains some 200 species.

Porosity-Driven Approaches to Model Fouling Effects on Flow Field

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Nicola Casari ◽  
Alessio Suman ◽  
Michele Pinelli
Keyword(s):  
Gas Turbines ◽  
Computational Grid ◽  
Comprehensive Analysis ◽  
Solid Particles ◽  
Heavy Duty ◽  
Air Contamination ◽  
Performance Reduction ◽  
Main Effects ◽  
Number Of Particles ◽  
Large Deposits

Abstract Air contamination by solid particles represents a real hazard for compressors for both heavy-duty and aeropropulsion gas turbines. Particles impacting the inner surfaces of the machine can stick to such surfaces or erode them. The presence of deposits entails a reduction in performance, in a phenomenon commonly referred to as fouling. As the severity of the problem increases, the performance reduction can become so big to demand engine shut down and offline washing. Numerical modeling is one of the techniques employed for tackling the fouling problem. In this work, an innovative procedure is proposed to evaluate the losses and the variation in the fluid flow due to the deposits. Specifically, as the deposit grows, it is assumed that it forms a porous medium attached to the wall. The porosity of this zone (related to the packing of the particles and to the number of particles that sticks to that portion of the wall) is responsible for the deposition-induced losses. Different approaches to compute such losses are proposed and discussed. By using this methodology, the two main effects of fouling (variation in roughness and in shape of the airfoil) can be easily included in a comprehensive analysis of the variation of the performance of the compressor over time. Furthermore, this approach overcomes the difficulties that may arise by using a mesh morphing technique. The computational grid is not modified, and thus, its quality is retained, without remeshing requirements, even for large deposits.

scholarly journals Evaluasi Kinerja Campuran Beraspal dengan Bitumen Hasil Ekstraksi Penuh dari Asbuton

2018 ◽  
Vol 24 (1) ◽  
pp. 62
Author(s):  
Nyoman Suaryana ◽  
Iwan Susanto ◽  
Yohannes Ronny ◽  
Ida Rumkita Sembayang
Keyword(s):  
Tensile Strain ◽  
Asphalt Mixtures ◽  
Rolled Sheet ◽  
Asphaltic Concrete ◽  
Natural Rock ◽  
Asphalt Mix ◽  
Marshall Stability ◽  
Oil Penetration ◽  
Hot Rolled ◽  
Large Deposits

Asbuton is a natural rock asphalt that can be found on the island of Buton in Southeast Sulawesi province, has a large deposits but not yet well utilized. This research aims to find out the performance of asphalt mixtures AC-WC (Asphaltic Concrete Wearing Course) and HRS-WC (Hot Rolled Sheet Wearing Course) using bitumen results from full extraction of asbuton. The research was done by experimental methods through laboratory tests then its performance was compared to convensional mixtures using asphalt oil with penetration grade of 60. The results obtained showed that the bitumen of asbuton did not meet the specification of bitumen based on penetration grade. Characteristics of hot mixture asphalt using bitumen of asbuton showed better performance in terms of the Marshall stability namely 1871 kg higher than the convensional hotmixture of asphalt, with 1100 kg for AC-WC and 1241.9 kg compared with 1094 kg for HRS-WC. In addition, the results of deformation resistance tests showed asphalt mix with pure asbuton  more resistant to rutting shown by higher dynamic stability value namely 4200 track/mm compared with 492 track/mm for AC-WC and 2739 track/mm compared with 325 track/mm. The modulus resilient value of mix with pure asbuton is also higher at temperature of 25°C and relatively the sameat temperatures of 35°C and 45°C. While the resistance of  fatigue for AC-WC and HRS-WC on the test tensile strain of 150 µs were relatively the same as hotmix asphalt using asphalt oil penetration grade of 60, but on test of  a larger tensile strain has worse fatigue resistance, especially for AC-WC.

Recovery Copper from a Complex Copper Sulfide Ore of Yunnan by Using Flotation

2015 ◽  
Vol 737 ◽  
pp. 839-842
Author(s):  
Yi Jie Wang ◽  
Shu Ming Wen ◽  
Dan Liu ◽  
Chuan Fa Cui ◽  
Bin Zhang
Keyword(s):  
Copper Sulfide ◽  
Sodium Sulfide ◽  
Optimal Conditions ◽  
Copper Ore ◽  
Copper Concentrate ◽  
Sulfide Ore ◽  
Open Test ◽  
Copper Sulfide Ore ◽  
Complex Copper ◽  
Large Deposits

Copper ore is the main mineral for the large deposits. Copper minerals are mostly consisting of chalcopyrite, secondly consisting of bornite, there are traces of processing copper blue and malachite, the mineral is disseminated by coarse granularity. This mineral is easy to processing. Production process was using by the process of grinding-flotation. After grinding fineness, lime dosage, sodium sulfide dosage, collector and frother dosage, were determined by the open test. Closed circuit experiment was conducted by those optimal conditions identified in the above test, the recovery of copper concentrate is 88.38% and the grade of copper concentrate is 14.37%.

scholarly journals CONCERNING THE ORIGIN OF THE WHITE QUARTZ SANDS OF NORTHERN PUERTO RICO

1969 ◽  
Vol 17 (2) ◽  
pp. 157-170
Author(s):  
James Thorp ◽  
Leslie Rockwell Smith
Keyword(s):  
Puerto Rico ◽  
Close Association ◽  
Acid Leaching ◽  
San Juan ◽  
Residual Soils ◽  
Forming Process ◽  
White Sand ◽  
Quartz Sands ◽  
High Degree ◽  
Large Deposits

The origin of the large deposits of almost pure white quartz sands which occur within the area occupied by the Tertiary limestones of northern Puerto Rico have long been a source of puzzlement to geologists. The largest areas occur within a mile or so of the seacoast in association with Tertiary deposits but are unconformable with them. Many of them are found in association with the remnants of lagoons which were cut off from the sea by the San Juan formation. Some deposits are also in fairly close association with the latter formation in some places. Smaller areas occur well within the limestone hills. Examinations of limestone outcrops and of residual soils within the limestone hills indicate that a large amount of sand originally came from the solution of layers of impure limestone which formerly overlay the district. It is altogether probable that some of the sands have been blown inland from the broken up San Juan formation and later leached of their lime. There is some evidence to support the theory that some of these sands may have been left in or near their present position along the shore of former lagoons which have since been drained by a slight emergence of the coast. There is but little question but that the smaller deposits several miles inland and well within the limestone hills are the residuum left from the dissolution of the limestones. The whiteness and purity of the sands are due to the soil forming process known as podzolization (acid leaching and eluviation) which in this case has taken place largely under conditions of high rainfall and poor subdrainage and to a less extent under well drained conditions. Some of the deeper deposits which are now well drained have been more or less piled up by the winds since they were bleached. We can therefore state with reasonable assurance that the quartz sands have come from the various sources above mentioned but that they are white because of a high degree of "podzolic" leaching which has affected them since they accumulated. Millions of acres of similar soils which have been carefully studied by soil scientists in the southeastern United States have furnished the evidence for this explanation of the origin of Puerto Rico's white sand deposits.

scholarly journals Coordination Between Fission Yeast Glucan Formation and Growth Requires a Sphingolipase Activity

Genetics ◽  
2001 ◽  
Vol 158 (4) ◽  
pp. 1397-1411 ◽  
Author(s):  
Anna Feoktistova ◽  
Paula Magnelli ◽  
Claudia Abeijon ◽  
Pilar Perez ◽  
Robert L Lester ◽  
...  
Keyword(s):  
Cell Wall ◽  
Secretory Pathway ◽  
Temperature Sensitive ◽  
Cell Wall Formation ◽  
Wild Type ◽  
Wall Formation ◽  
Biochemical Analyses ◽  
Membrane Spanning ◽  
Mutant Cells ◽  
Large Deposits

Abstractcss1 mutants display a novel defect in Schizosaccharomyces pombe cell wall formation. The mutant cells are temperature-sensitive and accumulate large deposits of material that stain with calcofluor and aniline blue in their periplasmic space. Biochemical analyses of this material indicate that it consists of α- and β-glucans in the same ratio as found in cell walls of wild-type S. pombe. Strikingly, the glucan deposits in css1 mutant cells do not affect their overall morphology. The cells remain rod shaped, and the thickness of their walls is unaltered. Css1p is an essential protein related to mammalian neutral sphingomyelinase and is responsible for the inositolphosphosphingolipid-phospholipase C activity observed in S. pombe membranes. Furthermore, expression of css1+ can compensate for loss of ISC1, the enzyme responsible for this activity in Saccharomyces cerevisiae membranes. Css1p localizes to the entire plasma membrane and secretory pathway; a C-terminal fragment of Css1p, predicted to encode a single membrane-spanning segment, is sufficient to direct membrane localization of the heterologous protein, GFP. Our results predict the existence of an enzyme(s) or process(es) essential for the coordination of S. pombe cell wall formation and division that is, in turn, regulated by a sphingolipid metabolite.

scholarly journals The speciation of Australopithecus and Paranthropus was caused by introgression from the Gorilla lineage

2018 ◽  
Author(s):  
Johan Nygren
Keyword(s):  
Mitochondrial Dna ◽  
Subcutaneous Fat ◽  
Conclusive Evidence ◽  
Great Toe ◽  
Lineage Sorting ◽  
Large Deposits

The discovery of Paranthropus deyiremeda in 3.3–3.5 million year old fossil sites in Afar (Haile-Selassie, 2015), together with 30% of the gorilla genome showing lineage sorting between humans and chimpanzees (Scally, 2012), and a NUMT (“nuclear mitochondrial DNA segment”) that is shared by both gorillas, humans and chimpanzees, and that dates back to 6 million years ago (Popadin, 2017), is conclusive evidence that introgression from the gorilla lineage caused the speciation of both the Australopithecus lineage and the Paranthropus lineage, providing a lens into the gorilla-like features within Paranthropus, as well as traits within Homo that originate from the gorilla branch, such as a high opposable thumb index (Almécija, 2015), an adducted great toe (Tocheri, 2011; McHenry, 2006), and large deposits of subcutaneous fat.

scholarly journals The speciation of Australopithecus and Paranthropus was caused by introgression from the Gorilla lineage

2018 ◽  
Author(s):  
Johan Nygren
Keyword(s):  
Mitochondrial Dna ◽  
Subcutaneous Fat ◽  
Conclusive Evidence ◽  
Great Toe ◽  
Lineage Sorting ◽  
Large Deposits

The discovery of Paranthropus deyiremeda in 3.3–3.5 million year old fossil sites in Afar (Haile-Selassie, 2015), together with 30% of the gorilla genome showing lineage sorting between humans and chimpanzees (Scally, 2012), and a NUMT (“nuclear mitochondrial DNA segment”) that is shared by both gorillas, humans and chimpanzees, and that dates back to 6 million years ago (Popadin, 2017), is conclusive evidence that introgression from the gorilla lineage caused the speciation of both the Australopithecus lineage and the Paranthropus lineage, providing a lens into the gorilla-like features within Paranthropus, as well as traits within Homo that originate from the gorilla branch, such as a high opposable thumb index (Almécija, 2015), an adducted great toe (Tocheri, 2011; McHenry, 2006), and large deposits of subcutaneous fat.

Porosity Driven Approaches to Model Fouling Effects on Flow Field

2019 ◽  
Author(s):  
Nicola Casari ◽  
Alessio Suman ◽  
Michele Pinelli
Keyword(s):  
Gas Turbines ◽  
Computational Grid ◽  
Comprehensive Analysis ◽  
Solid Particles ◽  
Heavy Duty ◽  
Air Contamination ◽  
Performance Reduction ◽  
Main Effects ◽  
Over Time ◽  
Large Deposits

Abstract Air contamination by solid particles represents a real hazard for compressors for both heavy-duty and aero-propulsion gas turbines. Particles impacting the inner surfaces of the machine can stick to such surfaces or erode them. The presence of deposits entails the reduction in performance of the machinery. As the severity of the problem increases, the performance reduction can become so big to demand engine shut-down and off-line washing. Numerical modeling is one of the techniques employed for tackling the fouling problem. In this work, an innovative procedure is proposed in order to evaluate the losses and the variation in the fluid flow due to the deposits. Specifically, as the deposit grows, it is assumed it forms a porous medium attached to the wall. The porosity of this zone (related to the packing of the particles and to the amount of particles that sticks in to a zone) is responsible for the deposition-induced losses. Different approaches to compute such losses are proposed and discussed. By using this methodology, the two main effects of fouling (variation in roughness and in shape of the airfoil) can be easily included in a comprehensive analysis of the variation of the performance of the compressor over time. Furthermore, this approach overcomes the difficulties that may arise by using a mesh morphing technique. The computational grid is not modified and thus its quality is retained, without remeshing requirements, even for large deposits.

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