Insights from geodynamical modeling on possible fates of continental mantle lithosphere: collision, removal, and overturnThis article is one of a series of papers published in this Special Issue on the theme Lithoprobe — parameters, processes, and the evolution of a continent.

2010 ◽  
Vol 47 (4) ◽  
pp. 541-563 ◽  
Author(s):  
Russell N. Pysklywec ◽  
Oguz Gogus ◽  
J. Percival ◽  
A. R. Cruden ◽  
C. Beaumont
Keyword(s):  
Late Stage ◽  
Continental Collision ◽  
Density Stratification ◽  
Mantle Lithosphere ◽  
Special Issue ◽  
Tectonically Active ◽  
Tectonic Environments

Geodynamic modeling demonstrates various modes of behaviour of the tectonically active continental mantle lithosphere. At continental collision, mantle lithosphere below thickening crust can be accommodated by mixed subduction-like consumption and viscous drip-like instability, depending on the material rheology, temperature, and convergence velocity. Late-stage slab steepening, dual-sided and ablative consumption, and breakoff can occur as the buoyant crust resists subduction. Removal of accreted crust by erosion can modify how even the deepest portions of the mantle lithosphere evolves during contraction. When gravitational forcing rather than plate shortening dominates, mantle lithosphere may be removed through viscous dripping-like instability or delamination. The removal induces crustal heating, modified topography, and deformation, but distinctive styles of these develop depending on whether mantle lithosphere delaminates or drips. With a modified density stratification postulated for the Archean, relatively buoyant mantle lithosphere may undergo an in-situ overturn when triggered by unstable dense eclogite and basal traction. This causes a pulse of rapid crustal heating as hot lowermost lithosphere is brought into contact with the base of the crust. As an interpretive tool, the geodynamic experiments illustrate some of the dynamically feasible modes of behaviour and controlling parameters for the continental mantle lithosphere in ancient to modern tectonic environments.

The Total Synthesis of Rhabdastrellic Acid A

2018 ◽  
Author(s):  
Yaroslav Boyko ◽  
Christopher Huck ◽  
David Sarlah
Keyword(s):  
Total Synthesis ◽  
Late Stage ◽  
Cross Coupling ◽  
Side Chains ◽  
General Strategy ◽  
Modular Approach ◽  
Linear Sequence ◽  
Generating Sequence ◽  
First Time

<div>The first total synthesis of rhabdastrellic acid A, a highly cytotoxic isomalabaricane triterpenoid, has been accomplished in a linear sequence of 14 steps from commercial geranylacetone. The prominently strained <i>trans-syn-trans</i>-perhydrobenz[<i>e</i>]indene core characteristic of the isomalabaricanes is efficiently accessed in a selective manner for the first time through a rapid, complexity-generating sequence incorporating a reductive radical polyene cyclization, an unprecedented oxidative Rautenstrauch cycloisomerization, and umpolung 𝛼-substitution of a <i>p</i>-toluenesulfonylhydrazone with in situ reductive transposition. A late-stage cross-coupling in concert with a modular approach to polyunsaturated side chains renders this a general strategy for the synthesis of numerous family members of these synthetically challenging and hitherto inaccessible marine triterpenoids.</div>

Reductive Cleavage of Secondary Sulfonamides: Converting Terminal Functional Groups into Versatile Synthetic Handles

2019 ◽  
Author(s):  
Patrick Fier ◽  
Suhong Kim ◽  
Kevin M. Maloney
Keyword(s):  
Functional Groups ◽  
Late Stage ◽  
Reductive Cleavage ◽  
Bioactive Molecules ◽  
General Method

Sulfonamides are pervasive in drugs and agrochemicals, yet are typically considered as terminal functional groups rather than synthetic handles. To enable the general late-stage functionalization of secondary sulfonamides, we have developed a mild and general method to reductively cleave the N-S bonds of sulfonamides to generate sulfinates and amines, components which can further react <i>in-situ</i> to access a variety of other medicinally relevant functional groups. The utility of this platform is highlighted by the selective manipulation of several complex bioactive molecules.

scholarly journals Magmatic flare-up causes crustal thickening at the transition from subduction to continental collision

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Carlos E. Ganade ◽  
Pierre Lanari ◽  
Daniela Rubatto ◽  
Joerg Hermann ◽  
Roberto F. Weinberg ◽  
...  
Keyword(s):  
Production Rate ◽  
Continental Margin ◽  
Subduction Zones ◽  
Continental Collision ◽  
Crustal Thickening ◽  
Time Intervals ◽  
West Gondwana ◽  
Continental Arc ◽  
Order Of Magnitude

AbstractAbove subduction zones, magma production rate and crustal generation can increase by an order of magnitude during narrow time intervals known as magmatic flare-ups. However, the consequences of these events in the deep arc environment remain poorly understood. Here we use petrological and in-situ zircon dating techniques to investigate the root of a continental arc within the collisional West Gondwana Orogen that is now exposed in the Kabyé Massif, Togo. We show that gabbros intruded 670 million years ago at 20–25 km depth were transformed to eclogites by 620 million years ago at 65–70 km depth. This was coeval with extensive magmatism at 20–40 km depth, indicative of a flare-up event which peaked just prior to the subduction of the continental margin. We propose that increased H2O flux from subduction of serpentinized mantle in the hyper-extended margin of the approaching continent was responsible for the increased magma productivity and crustal thickening.

scholarly journals Combined Photoredox and Carbene Catalysis for the Synthesis of Ketones from Carboxylic Acids

2020 ◽  
Author(s):  
Anna Davies ◽  
keegan fitzpatrick ◽  
Rick Betori ◽  
Karl Scheidt
Keyword(s):  
Carboxylic Acids ◽  
Late Stage ◽  
Pharmaceutical Compounds ◽  
Single Electron ◽  
Photoredox Catalysis ◽  
Radical Coupling ◽  
Electron Reduction

Disclosed herein is the development of a novel single-electron reduction of acyl azoliums for the formation of ketones from carboxylic acids. Facile construction of the acyl azolium <i>in situ</i> followed by a radical-radical coupling was made possible using merged NHC-photoredox catalysis. The utility of this protocol in synthesis was demonstrated in the late-stage functionalization of a variety of pharmaceutical compounds.

scholarly journals Architecture and Engineering: The Challenges—Trends—Achievements

Buildings ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 181
Author(s):  
Oleg Kapliński ◽  
Wojciech Bonenberg
Keyword(s):  
Subject Matter ◽  
Laboratory Tests ◽  
Research Field ◽  
Cost Calculation ◽  
Spatial Structures ◽  
Special Issue ◽  
Field Investigations ◽  
New Research ◽  
Current Special Issue

The current Special Issue is addressed to architects and engineers. Design and research are areas connecting their activities. A review of 17 published articles confirms the fact that the interface between architecture and engineering is multidimensional. The ways of finding points of contact between the two industries are highlighted. This is favoured by the dynamically changing reality, supported by new design paradigms and new research techniques. The multi-threaded subject matter of the articles is reduced to six blocks: research scopes, methods, design aspects, context, nature of research, and economy and cost calculation. Each of the articles in these six blocks has its weight, and so, in the “Nature of research” block, the following areas have been underscored: laboratory tests, in situ research, field investigations, and street perception experiments. The “Design aspects” block includes design-oriented thinking, geometrical forms, location of buildings, cost prediction, attractor and distractor elements, and shaping spatial structures. The new design and research tools are an inspiration and a keystone bonding architects and engineers.

Special issue on parallel applications for in-situ computing on the next-generation computing platforms

2018 ◽  
Vol 33 (3) ◽  
pp. 429-430
Author(s):  
Gabriele Mencagli ◽  
Felipe MG França ◽  
Cristiana Barbosa Bentes ◽  
Leandro Augusto Justen Marzulo ◽  
Mauricio Lima Pilla
Keyword(s):  
Parallel Applications ◽  
Next Generation ◽  
Special Issue ◽  
Generation Computing ◽  
Computing Platforms

scholarly journals Special Issue on Remote Sensing of Snow and Its Applications

Geosciences ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 277 ◽  
Author(s):  
Ali Nadir Arslan ◽  
Zuhal Akyürek
Keyword(s):  
Remote Sensing ◽  
Snow Cover ◽  
Land Surface ◽  
Climate Models ◽  
Weather Forecasting ◽  
Special Issue ◽  
Carbon Cycles ◽  
Wide Range ◽  
Remote Sensing Techniques

Snow cover is an essential climate variable directly affecting the Earth’s energy balance. Snow cover has a number of important physical properties that exert an influence on global and regional energy, water, and carbon cycles. Remote sensing provides a good understanding of snow cover and enable snow cover information to be assimilated into hydrological, land surface, meteorological, and climate models for predicting snowmelt runoff, snow water resources, and to warn about snow-related natural hazards. The main objectives of this Special Issue, “Remote Sensing of Snow and Its Applications” in Geosciences are to present a wide range of topics such as (1) remote sensing techniques and methods for snow, (2) modeling, retrieval algorithms, and in-situ measurements of snow parameters, (3) multi-source and multi-sensor remote sensing of snow, (4) remote sensing and model integrated approaches of snow, and (5) applications where remotely sensed snow information is used for weather forecasting, flooding, avalanche, water management, traffic, health and sport, agriculture and forestry, climate scenarios, etc. It is very important to understand (a) differences and similarities, (b) representativeness and applicability, (c) accuracy and sources of error in measuring of snow both in-situ and remote sensing and assimilating snow into hydrological, land surface, meteorological, and climate models. This Special Issue contains nine articles and covers some of the topics we listed above.

scholarly journals Gametogenesis and Spawning ofSolenastrea bournoniandStephanocoenia interseptain Southeast Florida, USA

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Jenna R. Lueg ◽  
Alison L. Moulding ◽  
Vladimir N. Kosmynin ◽  
David S. Gilliam
Keyword(s):  
Histological Examination ◽  
Late Stage ◽  
Full Moon ◽  
Reproductive Mode ◽  
Tissue Samples ◽  
Broadcast Spawning ◽  
First Report ◽  
Gametogenic Cycle ◽  
Oocyte Resorption

This study constitutes the first report of the gametogenic cycle of the scleractinian coralsSolenastrea bournoniandStephanocoenia intersepta. Tissue samples were collected near Ft. Lauderdale, Florida, USA between July 2008 and November 2009 and processed for histological examination in an effort to determine reproductive mode and potential spawning times. BothS. bournoniandS. interseptaare gonochoric, broadcast spawning species. Gametogenesis ofS. bournonibegan in April or May whileS. interseptahad a much longer oogenic cycle that began in December with spermatogenesis beginning in July. Though spawning was not observedin situ, spawning was inferred from the decrease of late stage gametes in histological samples. In addition, histological observations of oocyte resorption and released spermatozoa were used to corroborate spawning times. Data indicate thatS. bournonispawns in September whileS. interseptaspawns after the full moon in late August or early September.

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