scholarly journals Textures and Chemical Compositions of Nb-Bearing Minerals and Nb Mineralization in the Shuangshan Nepheline Syenite Pluton, East Qinling, China

Minerals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1163
Author(s):  
Hong Wang ◽  
Yong Tang ◽  
Yu-Sheng Xu ◽  
Hui Zhang ◽  
Zheng-Hang Lv ◽  
...  
Keyword(s):  
Hydrothermal Alteration ◽  
Nepheline Syenite ◽  
Henan Province ◽  
The Other ◽  
Chemical Compositions ◽  
Alkaline Complex ◽  
Hydrothermal Zircon ◽  
Quantitative Calculation ◽  
Other Hand ◽  
Different Origins

The Shuangshan alkaline complex located in the Henan province of China is a newly discovered, potentially giant niobium (Nb) deposit. A variety of Nb-bearing minerals including pyrochlore, zircon, and titanite have been identified in this deposit. Distinct textural and chemical differences of pyrochlore and zircon indicate that both have different origins. The magmatic pyrochlore and zircon both have euhedral grains with small sizes. On the other hand, hydrothermal pyrochlore is mainly intergrown on the edge or inside of hydrothermal zircon in the form of an aggregate. Compared with magmatic pyrochlore, the contents of F, Ca, and Na in hydrothermal pyrochlore are obviously high. The texture and composition of hydrothermal pyrochlore and zircon indicate that Ca-bearing hydrothermal alteration resulted in the migration of Nb from Nb-bearing zircon and the reprecipitation of Nb to form aggregate pyrochlore. However, the quantitative calculation shows that the amount of Nb migrated from zircon is very small. Therefore, this study suggests that hydrothermal alteration plays a certain role in the redistribution of Nb, but the enrichment of Nb is limited.

Contrasting signatures of the sources and types of aerosols in the western and eastern Himalayas: Radiative implications

2021 ◽  
Author(s):  
Arun Bs ◽  
Mukunda Gogoi ◽  
Prashant Hegde ◽  
Suresh Babu
Keyword(s):  
Mineral Dust ◽  
Water Soluble ◽  
The Other ◽  
Anthropogenic Source ◽  
Chemical Compositions ◽  
Eastern Himalayas ◽  
Chemical Aging ◽  
Other Hand ◽  
Secondary Formation ◽  
The Impact

<p>The rapid changes in the pattern of atmospheric warming over the Himalayas, along with severe degradation of Himalayan glaciers in recent years suggest the inevitability of accurate source characterization and quantification of the impact of aerosols on the Himalayan atmosphere and snow. In this regard, extensive study of the chemical compositions of aerosols at two distinct regions, Himansh (32.4<sup>ᴼ</sup>N, 77.6<sup>ᴼ</sup>E, ~ 4080 m a.s.l) and Lachung (27.4<sup>ᴼ</sup>N, 88.4<sup>ᴼ</sup>E, ~ 2700 m a.s.l), elucidates distinct signatures of the sources and types of aerosols prevailing over the western and eastern parts of Himalayas. The mass-mixing ratios of water-soluble (Na<sup>+</sup>, NH<sub>4</sub><sup>+</sup>, K<sup>+</sup>, Ca<sup>2+</sup>, Mg<sup>2+</sup>, Cl-, SO<sub>4</sub><sup>2-</sup>, NO<sub>3</sub><sup>-</sup>, MSA<sup>-</sup>, C<sub>2</sub>O<sub>4</sub><sup>2-</sup>), carbonaceous (EC, OC, WSOC) and selected elemental (Al, Fe, Cu, Cr, Ti) species depicted significant abundance of mineral dust aerosols (~ 67%), along with a significant contribution of carbonaceous aerosols (~ 9%) during summer to autumn (August-October) over the western Himalayan site. On the other hand, the eastern Himalayan site is found to be dominant of OC (~ 53% in winter) followed by SO<sub>4</sub><sup>2-</sup> (as high as 37% in spring) and EC (8-12%) during August to February. However, OC/EC and WSOC/OC ratios showed significantly higher values over both the sites (~ 12.5, and 0.56 at Himansh; ~ 5.7 and ~ 0.74 at Lachung) indicating the secondary formation of organic aerosols via chemical aging over both the sites. The enrichment factors estimated from the concentrations of trace elements over the western Himalayan site revealed the influence of anthropogenic source contribution from the regional hot-spots of Indo-Gangetic Plains, in addition to that of west Asia and the Middle East countries. On the other hand, the source apportionment of aerosols (based on positive matrix factorization - PMF model) over the eastern Himalayas demonstrated the biomass-burning aerosols (25.94%), secondary formation of aerosols via chemical aging (15.94%), vehicular and industrial emissions (20.54%), primary emission sources associated with mineral dust sources (22.28%) and aged secondary aerosols (15.31%) as the major sources of aerosols. Due to abundant anthropogenic source impacts at the eastern Himalayan site, the atmospheric forcing is most elevated in winter (13.4 ± 4.4 Wm<sup>-2</sup>), which is more than two times the average values seen at the western Himalayan region during the study period. The heavily polluted eastern part of the IGP is a potential anthropogenic source region contributing to the aerosol loading at the eastern Himalayas. These observations have far-reaching implications in view of the role of aerosols on regional radiative balance and their impact on snow/glacier coverage.</p>

scholarly journals Dias en Da Gama, Van Wyk Louw en Camões (her)besoek

Literator ◽  
2014 ◽  
Vol 35 (1) ◽  
Author(s):  
Johan L. Coetser
Keyword(s):  
South African ◽  
World History ◽  
The Other ◽  
The South ◽  
Other Hand ◽  
Epic Poem ◽  
African Coast ◽  
Radio Play ◽  
Different Origins

Dias and Da Gama, Van Wyk Louw and Camões (re)visited. Although he was the first Portuguese explorer who rounded the southernmost cape of Africa, world history does not herald Bartholomew Dias as an important figure. His compatriot Vasco da Gama was the first mariner who reached the Orient by navigating around the Cape. Despite Dias’s relative historical unimportance, N.P. van Wyk Louw preferred to write a radio play about him and his journey around the South African coast. Luís Vaz de Camões, on the other hand, wrote an epic poem about da Gama’s journey, which he titled Os Lusíadas (1572), or The sons of Portugal. The question I set out to answer, relates to the position and importance that the playwright of Dias (1952) attaches to themes in Canto 5 of Os Lusíadas (1572). I assume that the two can be compared due to the presence of the mythical character Adamastor in both. As in Os Lusíadas (1572), Adamastor takes the form of a storm in Dias (1952). I conclude that, in spite of different origins, both texts are allegorical and national in character. The differences in origin inspired a revised reading of Dias (1952).

scholarly journals Chemical compositions of amphiboles and their references to formation conditions of granitoids from Nam Rom and Song Ma massifs, Northwest Vietnam

2020 ◽  
Vol 42 (1) ◽  
pp. 80-92
Author(s):  
Pham Ngoc Can ◽  
Tran Tuan Anh ◽  
Tran Trong Hoa ◽  
Vu Hoang Ly ◽  
Pham Thi Phuong Lien ◽  
...  
Keyword(s):  
Geochemical Characteristics ◽  
The Other ◽  
Chemical Compositions ◽  
Formula Unit ◽  
Fine Grained ◽  
Basic Stage ◽  
Other Hand ◽  
Formation Conditions ◽  
Similar Formation

In this paper, the mineralogical and geochemical characteristics of amphiboles and plagioclases of granitoids from the Nam Rom and Song Ma massifs have been investigated to understand their formation conditions. The Nam Rom amphibole and plagioclase are subhedral to euhedral fine- to medium-grained crystals. Whereas, the Song Ma amphibole and plagioclase are anhedral to subhedral fine-grained crystals. Geochemical compositions of amphiboles suggest that Nam Rom and Song Ma amphiboles are edenite and ferro-edenite, respectively. Nam Rom edenite has higher contents of basic constituents (Mg and Ca) and lower contents of felsic constituents (Na and K) compared with the Song Ma ferro-edenite. On the other hand, Si-(Na+K) and Si-Ca apfu ratios of the Nam Rom edenite and the Song Ma ferro-edenite and Al/(Na+K)-Al/(Ca+Na+K) atom per formula unit (apfu) ratios of the Nam Rom edenite and andesine and the Song Ma ferro-edenite, andesine and oligoclase are similar. Formation conditions of the Nam Rom and Song Ma granitoids were calculated using amphibole-plagioclase geobarometer. The Nam Rom granitoid was formed at 3.07-5.32 kbar (10.1-17.6 km under paleo-surface) and 750-785°C. The Song Ma granitoid was formed at 1.04-3.08 kbar (3.4-10.2 km under paleo-surface) and 715-745°C. Therefore, Nam Rom and Song Ma granitoids are thought to be crystallized from the same magma. The former was formed from the immature and more basic stage of magma; the latter was formed from the mature and more felsic stage of magma.

scholarly journals Materials research in conservation and heritology

1970 ◽  
pp. 129
Author(s):  
Ulla Knuutinen
Keyword(s):  
Cultural Heritage ◽  
Environmental Conditions ◽  
The Other ◽  
Reliable Information ◽  
Chemical Compositions ◽  
Other Hand ◽  
Materials Research ◽  
Properties Of Materials ◽  
Cultural Heritage Objects ◽  
Physical Changes

This article is based on the dissertation by the author. It creates a connection between materials research and conservation and heritology. Materials research is a part of multidisciplinary heritology and it has an important role in preserving cultural heritage. If reliable information for the documentation is needed about the materials in an object, on the origin of the object, on the authenticity of the object or on whether any restoration has been carried out previously, analyses that reveal chemical compositions must be performed. On the other hand, the materials research can be focused on examining the ageing properties of materials to find out the chemical and physical changes caused by different environmental conditions. This kind of research benefits the preservation of cultural heritage objects, because results can be applied to both preventive and active conservation. Furthermore, materials research is needed for testing and examining the conservation and restoration methods. 

scholarly journals Comparing the toxicity of two fumigants to insects from the field vs laboratory — does insect origin matter?

2017 ◽  
Vol 70 ◽  
pp. 323
Author(s):  
A.J. Najar-Rodriguez ◽  
M.K.D. Hall ◽  
C.R. Wilks ◽  
A.R. Adlam ◽  
S. Brierley ◽  
...  
Keyword(s):  
New Zealand ◽  
Bark Beetle ◽  
Methyl Bromide ◽  
The Other ◽  
Alpha Pinene ◽  
Controlled Conditions ◽  
Other Hand ◽  
Significant Difference ◽  
Different Origins

The golden-haired bark beetle, Hylurgus ligniperda, is one of the most common insects normally associated with New Zealand export logs. Here we tested the dose-mortality responses of H. ligniperda adults, from two different origins (field vs laboratory), to methyl bromide (MB) — the most widely used fumigant worldwide and ethanedinitrile (EDN), a new fumigant currently being considered as very promising for MB replacement. Naked insects were fumigated with either MB or EDN at 10˚C for 4 and 3 hours, respectively. Adults from the laboratory had been reared on an arti cial diet and under controlled conditions for over 10 generations at the time of the experiments. Field adults, on the other hand, had been recently collected from Lindgren funnel traps with lures of alpha-pinene and ethanol. Our results showed that there is a significant difference in the tolerance to the two fumigants tested according to the origin of the insects, with field-collected adults being less tolerant to MB and EDN than laboratory-reared ones. The implications of our results for the development of disinfestation schedules for New Zealand export logs will be discussed.

A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

Life Beyond 1MeV

1980 ◽  
Vol 38 ◽  
pp. 30-33
Author(s):  
K.H. Westmacott
Keyword(s):  
Electron Microscopy ◽  
Past Experience ◽  
The Other ◽  
Good Case ◽  
Other Hand ◽  
The U.S

Life beyond 1MeV – like life after 40 – is not too different unless one takes advantage of past experience and is receptive to new opportunities. At first glance, the returns on performing electron microscopy at voltages greater than 1MeV diminish rather rapidly as the curves which describe the well-known advantages of HVEM often tend towards saturation. However, in a country with a significant HVEM capability, a good case can be made for investing in instruments with a range of maximum accelerating voltages. In this regard, the 1.5MeV KRATOS HVEM being installed in Berkeley will complement the other 650KeV, 1MeV, and 1.2MeV instruments currently operating in the U.S. One other consideration suggests that 1.5MeV is an optimum voltage machine – Its additional advantages may be purchased for not much more than a 1MeV instrument. On the other hand, the 3MeV HVEM's which seem to be operated at 2MeV maximum, are much more expensive.

Can the Academic Self-Concept be Positive and Realistic?

2005 ◽  
Vol 19 (3) ◽  
pp. 129-132 ◽  
Author(s):  
Reimer Kornmann
Keyword(s):  
Academic Performance ◽  
Opposite Effect ◽  
Self Esteem ◽  
Point Of View ◽  
The Other ◽  
Self Concept ◽  
High Ability ◽  
Self Image ◽  
Other Hand

Summary: My comment is basically restricted to the situation in which less-able students find themselves and refers only to literature in German. From this point of view I am basically able to confirm Marsh's results. It must, however, be said that with less-able pupils the opposite effect can be found: Levels of self-esteem in these pupils are raised, at least temporarily, by separate instruction, academic performance however drops; combined instruction, on the other hand, leads to improved academic performance, while levels of self-esteem drop. Apparently, the positive self-image of less-able pupils who receive separate instruction does not bring about the potential enhancement of academic performance one might expect from high-ability pupils receiving separate instruction. To resolve the dilemma, it is proposed that individual progress in learning be accentuated, and that comparisons with others be dispensed with. This fosters a self-image that can in equal measure be realistic and optimistic.

Stories and the Self

2020 ◽  
Vol 32 (2) ◽  
pp. 47-58 ◽  
Author(s):  
Stefan Krause ◽  
Markus Appel
Keyword(s):  
Meta Analysis ◽  
The Self ◽  
The Other ◽  
Lower Degree ◽  
Contrast Effects ◽  
Self Perception ◽  
Self Perceptions ◽  
Other Hand ◽  
The One ◽  
Implicit And Explicit

Abstract. Two experiments examined the influence of stories on recipients’ self-perceptions. Extending prior theory and research, our focus was on assimilation effects (i.e., changes in self-perception in line with a protagonist’s traits) as well as on contrast effects (i.e., changes in self-perception in contrast to a protagonist’s traits). In Experiment 1 ( N = 113), implicit and explicit conscientiousness were assessed after participants read a story about either a diligent or a negligent student. Moderation analyses showed that highly transported participants and participants with lower counterarguing scores assimilate the depicted traits of a story protagonist, as indicated by explicit, self-reported conscientiousness ratings. Participants, who were more critical toward a story (i.e., higher counterarguing) and with a lower degree of transportation, showed contrast effects. In Experiment 2 ( N = 103), we manipulated transportation and counterarguing, but we could not identify an effect on participants’ self-ascribed level of conscientiousness. A mini meta-analysis across both experiments revealed significant positive overall associations between transportation and counterarguing on the one hand and story-consistent self-reported conscientiousness on the other hand.

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