scholarly journals Hydrothermal fields of the Piip submarine volcano, Komandorsky Back-Arc Basin: Chemistry and origin of vent mineralization and bubbling gas

1994 ◽  
Vol 41 ◽  
pp. 55-64
Author(s):  
Pavel V. Torokhov ◽  
Yuri A. Taran
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Isotopic Composition ◽  
Significant Role ◽  
Hydrothermal System ◽  
Submarine Volcano ◽  
Bacterial Sulphate Reduction ◽  
Back Arc ◽  
Hydrothermal Fields

Active thermal vents of the Piip submarine volcano were studied in 1990 from aboard sub­mersibles MIR 1 and 2. Samples of free gas and hydrothermal deposits were collected in the areas of thermal fluid discharge. Mineralogical, isotopic and microprobe studies of samples have shown, as the hydrothermal system cools, the high-temperature anhydrite association displayed at the surface is substituted by calcite-barite and later by calcite-barite-sulfide assemblages. The chemical and isotopic composition of gas and carbonates indicates the significant role of hydrocarbons from the sedimentary layers which, during the low-temperature stage, stimulate the processes of bacterial sulphate reduction. The evolution of a simular hydrothermal system is traced in the Great Caucasus barite deposits.

Authigenesis of native sulphur and dolomite in a lacustrine evaporitic setting (Hellín basin, Late Miocene, SE Spain)

2011 ◽  
Vol 148 (4) ◽  
pp. 655-669 ◽  
Author(s):  
J. LINDTKE ◽  
S. B. ZIEGENBALG ◽  
B. BRUNNER ◽  
J. M. ROUCHY ◽  
C. PIERRE ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Late Miocene ◽  
Heterotrophic Bacteria ◽  
Carbon Isotopic Composition ◽  
Sulphate Reduction ◽  
Se Spain ◽  
Carbon Isotopic ◽  
Bacterial Sulphate Reduction ◽  
Strong Depletion

AbstractAbundant sulphur is present in the Late Miocene evaporitic sequence of the lacustrine Hellín basin in SE Spain. Weathering of Triassic evaporites controlled the chemical composition of the Miocene lake. The lacustrine deposits comprise gypsum, marlstones, diatomites and carbonate beds. Sulphur-bearing carbonate deposits predominantly consist of early diagenetic dolomite. Abundant dolomite crystals with a spheroidal habit are in accordance with an early formation and point to a microbial origin. The carbon isotopic composition of the dolomite (δ13C values between −10 and −4‰) indicates mixing of lake water carbonate and carbonate derived from the remineralization of organic matter by heterotrophic bacteria. Dolomite precipitated syngenetically under evaporitic conditions as indicated by high oxygen isotope values (δ18O between +6 and +11‰). Nodules of native sulphur are found in gypsum, carbonate beds and marlstone layers. Sulphur formed in the course of microbial sulphate reduction, as reflected by its strong depletion in34S (δ34S values as low as −17‰). Near to the surface many of the sulphur nodules were in part or completely substituted by secondary gypsum, which still reflects the sulphur isotopic composition of native sulphur (−18 to −10‰). This study exemplifies the role of bacterial sulphate reduction in the formation of dolomite and native sulphur in a semi-enclosed lacustrine basin during Late Miocene time.

scholarly journals Norpa Signalling and the Seasonal Circadian Locomotor Phenotype in Drosophila

Biology ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 130
Author(s):  
Carlo Breda ◽  
Ezio Rosato ◽  
Charalambos P. Kyriacou
Keyword(s):  
Drosophila Melanogaster ◽  
Low Temperature ◽  
Circadian Clock ◽  
Significant Role ◽  
In Situ Hybridisation ◽  
Seasonal Effects ◽  
Seasonal Adaptations ◽  
Behavioural Effects

In this paper, we review the role of the norpA-encoded phospholipase C in light and thermal entrainment of the circadian clock in Drosophila melanogaster. We extend our discussion to the role of norpA in the thermo-sensitive splicing of the per 3′ UTR, which has significant implications for seasonal adaptations of circadian behaviour. We use the norpA mutant-generated enhancement of per splicing and the corresponding advance that it produces in the morning (M) and evening (E) locomotor component to dissect out the neurons that are contributing to this norpA phenotype using GAL4/UAS. We initially confirmed, by immunocytochemistry and in situ hybridisation in adult brains, that norpA expression is mostly concentrated in the eyes, but we were unable to unequivocally reveal norpA expression in the canonical clock cells using these methods. In larval brains, we did see some evidence for co-expression of NORPA with PDF in clock neurons. Nevertheless, downregulation of norpA in clock neurons did generate behavioural advances in adults, with the eyes playing a significant role in the norpA seasonal phenotype at high temperatures, whereas the more dorsally located CRYPTOCHROME-positive clock neurons are the likely candidates for generating the norpA behavioural effects in the cold. We further show that knockdown of the related plc21C encoded phospholipase in clock neurons does not alter per splicing nor generate any of the behavioural advances seen with norpA. Our results with downregulating norpA and plc21C implicate the rhodopsins Rh2/Rh3/Rh4 in the eyes as mediating per 3′ UTR splicing at higher temperatures and indicate that the CRY-positive LNds, also known as ‘evening’ cells are likely mediating the low-temperature seasonal effects on behaviour via altering per 3′UTR splicing.

scholarly journals Temperature-induced Glucosinolate Accumulation Is Associated with Expression of BrMYB Transcription Factors

HortScience ◽  
2013 ◽  
Vol 48 (1) ◽  
pp. 47-52 ◽  
Author(s):  
Veronica L. Justen ◽  
Vincent A. Fritz
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Gene Expression Analysis ◽  
Tissue Type ◽  
Temperature Dependent ◽  
Temperature Regimes ◽  
Health Promoting ◽  
Transcription Factor Expression ◽  
Low Temperature Treatments

Turnips (Brassica rapa. subsp. rapa L.) produce glucosinolates (GSLs), thioglucosides whose hydrolyzed derivatives have been shown to provide chemopreventive benefits. Two cultivars of turnips [‘Just Right’ (JR) and ‘Scarlet Queen’ (SQ)] were grown under three different temperature regimes to assess the role of temperature on GSL production in roots and shoots. When compared with low-temperature treatments, high-temperature treatments increased total and individual GSLs in a tissue- and genotype-specific manner. When compared with low-temperature treatments, total GSLs were ≈70% and 130% higher in JR shoots and roots, respectively, grown at high-temperature treatments. High temperatures also increased total GSLs in SQ shoots and roots by ≈80% and 85%, respectively, when compared with low temperatures. Gluconasturtiin (GNS, 2-phenylethyl GSL) concentration was inversely correlated with temperature with high-temperature treatments resulting in 20% and 48% less GNS than low-temperature treatments in JR and SQ roots, respectively. The indolic GSL, 1-methoxyglucobrassicin (1MGB; 1-methoxy-3-ylmethyl GSL), was the root GSL most elevated by increased temperature resulting in a 1000% increase on average in both cultivars between the low- and high-temperature treatments. These results show promise for the use of temperature to enhance the health-promoting properties of turnip because 1MGB has potent chemopreventive effects. Gene expression analysis suggests that some BrMYB transcription factor expression levels are associated with temperature-dependent changes in GSL accumulation; however, this association varies between cultivar and tissue type.

Hydrogen-Induced Blistering of SiC: The Role of Post-Implant Multi-Step Annealing Sequences

2006 ◽  
Vol 527-529 ◽  
pp. 855-858 ◽  
Author(s):  
G. Malouf ◽  
B. Poust ◽  
S. Hayashi ◽  
G. Yoshizawa ◽  
M.S. Goorsky
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Thin Layers ◽  
Low Temperature Annealing ◽  
Annealing Conditions ◽  
Annealing Step ◽  
Higher Temperature ◽  
Platelet Defects ◽  
Viable Approach

Hydrogen-exfoliation has become a viable approach to transfer SiC thin layers onto different substrate materials. However, little attention has been paid to the exfoliation-inducing annealing conditions. To investigate the annealing conditions, 4H SiC wafers were implanted with either 2.5×1016 H2 + cm-2 or 5.0×1016 cm-2at 37 KeV. Post-implant, multi-step annealing sequences were examined in order to promote more efficient blistering, and it was found that a low temperature initial annealing step (T ≈ 500°C) can decrease the annealing time necessary in the high temperature regime; this was attributed to a nucleation of hydrogen induced platelet defects during the low temperature annealing regime and efficient splitting during a higher temperature (900 °C) anneal. This process is similar to what is observed for InP and Si exfoliation, except that the annealing processes occur at higher temperature.

Thermographic Study of Elastomers III. Peculiarities of Crystallization of Natural Rubber

1967 ◽  
Vol 40 (2) ◽  
pp. 458-462
Author(s):  
B. Ya Teitel'baum ◽  
N. P. Anoshina
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Natural Rubber ◽  
Crystallization Process ◽  
Crystallographic Form ◽  
Sharp Difference ◽  
Thermographic Study ◽  
Low Temperature Crystallization ◽  
Temperature Crystallization

Abstract Thermographic (DTA) study reveals two independent melting regions of natural rubber crystallites and a gap between them which is determined by a sharp difference in the rates of the crystallization process. Crystallites formed at a low temperature (− 25° C) and at room temperatures are distinguished by the degree of development, but pertain to the same crystallographic form. High temperature crystals play the role of seed in low temperature crystallization. During the melting of low temperature crystallites of natural rubber, they recrystallize with a rise in the melting point (without reaching, however, room temperatures). The appearance of this phenomenon on the thermograms is determined by the relation between rates of crystallization and of heating in the course of the experiment. The rate of crystallization of natural rubber and the relative amount of crystallites formed at − 25° C were studied by DTA; the effect of rubber plasticization on these magnitudes was noted.

Exsolution and inversion in pigeonite from the Whin Sill, Northern England

1978 ◽  
Vol 36 (1) ◽  
pp. 474-475
Author(s):  
P.P.K. Smith
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Homogeneous Nucleation ◽  
Silicate Mineral ◽  
Antiphase Boundaries ◽  
Two Phase ◽  
Primitive Form ◽  
The Core ◽  
Nucleation Mechanisms ◽  
And Inversion

Grains of pigeonite, a calcium-poor silicate mineral of the pyroxene group, from the Whin Sill dolerite have been ion-thinned and examined by TEM. The pigeonite is strongly zoned chemically from the composition Wo8En64FS28 in the core to Wo13En34FS53 at the rim. Two phase transformations have occurred during the cooling of this pigeonite:- exsolution of augite, a more calcic pyroxene, and inversion of the pigeonite from the high- temperature C face-centred form to the low-temperature primitive form, with the formation of antiphase boundaries (APB's). Different sequences of these exsolution and inversion reactions, together with different nucleation mechanisms of the augite, have created three distinct microstructures depending on the position in the grain.In the core of the grains small platelets of augite about 0.02μm thick have farmed parallel to the (001) plane (Fig. 1). These are thought to have exsolved by homogeneous nucleation. Subsequently the inversion of the pigeonite has led to the creation of APB's.

The Role of Muslim Women in Civil Society In Promoting Values and Principles for Building Peace: Action Guide from The Qur’ān

Sains Insani ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 30-36
Author(s):  
Che Amnah Bahari ◽  
Fatimah Abdullah
Keyword(s):  
Civil Society ◽  
Lifelong Learning ◽  
Significant Role ◽  
Textual Analysis ◽  
Muslim Women ◽  
Peace Building ◽  
Analysis Method ◽  
Pluralistic Society ◽  
Women And Children

The whole world, the Muslim in particular has witnessed conflicts in different areas, which have hindered the developmental efforts of the nations concerned. It should be learned that most victims of these conflicts are women and children. This article attempts to elaborate the role of Muslims Women as a crucial segment in civil society in initiating peace building through nurturing process. It maintains that the adoption of the principles and values derived from the Qur’ān and Sunnah of the Prophet is necessary as a process of lifelong learning.  Those identified values constituted the framework of this article and it adopts the textual analysis method.   This article concludes that through the implementation of those values and frameworks for peace building, women as one of the important segments of civil society are able to play significant role towards initiating peace building and promoting peaceful co-existence in pluralistic society. Abstrak: Dunia Islam khususnya telah menyaksikan konflik di pelbagai daerah yang berbeza. Konflik ini telah menghalang usaha kearah pembangunan Kawasan yang berkenaan. Kebanyakan mangsa konflik ini adalah wanita dan kanak-kanak. Artikel ini cuba untuk menghuraikan peranan wanita Islam sebagai segmen penting dalam masyarakat madani dalam membangun proses kedamaian dengan mendidik dan memupuk prinsip dan nilai murni janaan al-Qur’an. Penggunaan prinsip dan nilai yang dikutip dari ayat-ayat Qur'an dan hadis Rasulullah adalah keperluan yang mendesak sebagai wadah bagi proses pembelajaran sepanjang hayat. Nilai-nilai yang dikenal pasti merupakan rangka kerja artikel ini, dan metod yang dirujuk adalah analisis teks. Artikel ini menyimpulkan bahawa melalui pelaksanaan nilai-nilai dan kerangka kerja Islam bagi proses kedamaian, wanita Islam dalam masyarakat madani mampu memainkan peranan penting dalam memulakan pembinaan keamanan dan menggalakkan kehidupan yang harmonis, sejahtera dan saling bantu membantu dalam masyarakat majmuk.

POLICY CHANGE – THE ROLE OF IDEAS AND POLICY ENTREPRENEURS

2018 ◽  
pp. 63-72
Author(s):  
Arwanto Arwanto ◽  
Wike Anggraini
Keyword(s):  
Policy Change ◽  
Significant Role ◽  
Policy Process ◽  
Policy Entrepreneurs ◽  
Multiple Streams ◽  
Policy Makers ◽  
Problem Framing ◽  
Exogenous Factors ◽  
The Relationship

ABSTRACT Understanding policy process involves many distinctive approaches. The most common are institutional, groups or networks, exogenous factors, rational actors, and idea-based approach. This paper discussed the idea-based approach to explain policy process, in this case policy change. It aims to analyse how ideas could assist people to understand policy change. What role do they play and why are they considered as fundamental element? It considers that ideas are belong to every policy actor, whether it is individual or institution. In order to answer these questions, this paper adopts Kingdon’s multi streams approach to analyse academic literatures. Through this approach, the relationship between ideas and policy change can be seen clearer. Ideas only can affect in policy change if it is agreed and accepted by policy makers. Therefore the receptivity of ideas plays significant role and it emerges policy entrepreneurs. They promote ideas (through problem framing, timing, and narrative construction) and manipulate in order to ensure the receptivity of ideas. Although policy entrepreneurs play significant role, political aspects remains the most important element in the policy process. Keywords: policy change, ideas, idea-based approach, Kingdon’s multiple streams, policy entrepreneurs.

Sign in / Sign up

Export Citation Format

Share Document