scholarly journals Tracking low-temperature tectonism of the St. Lawrence Platform and Humber Zone, southern Quebec Appalachians, through apatite and zircon (U–Th)/He thermochronology

2017 ◽  
Vol 54 (8) ◽  
pp. 827-849 ◽  
Author(s):  
J.M. Emberley ◽  
D.A. Schneider
Keyword(s):  
Low Temperature ◽  
Late Jurassic ◽  
Late Ordovician ◽  
Petroleum Exploration ◽  
Accelerated Cooling ◽  
Early Devonian ◽  
Late Cambrian ◽  
Thermal Maximum ◽  
Order Of Magnitude ◽  
The Subject

The St. Lawrence Platform (SLP) and Humber Zone (HZ) of the southern Quebec Appalachians have been the subject of extensive studies to resolve the degree of thermal maturation, yet the timing of the thermal maximum is not well understood. We have employed apatite (AHe) and zircon (ZHe) (U–Th)/He thermochronometry across a network of Late Cambrian to Late Ordovician siliciclastic and Grenvillian basement outcrops to resolve the thermal history below 200 °C. Single crystal dates from individual samples exhibit age dispersion by as much as 300 million years, with a strong positive to negative correlation with increasing effective uranium (eU) concentration. The data in the southwestern portion of the basin allow for thermal maxima of up to 200 °C during the Late Ordovician or Early Devonian. Regional burial trends combined with local estimates of paleogeothermal gradients indicate that, if sedimentation continued after the Late Ordovician, there was no significant increase in burial in southwestern portions of the SLP as previously suggested. Heating was followed by protracted cooling through 180–100 °C during the Late Jurassic and Early Cretaceous, and the cooling rate increased by an order of magnitude through the uppermost crust (80–60 °C) until ca. 100 Ma. Both the external and internal HZ sections experienced rapid cooling through the Silurian after a Taconic thermal maximum. The HZ witnessed protracted cooling through the Late Jurassic, followed by accelerated cooling until the present. Increased recognition of these low-temperature events can augment our understanding of the evolution of accretionary orogens, consequently increasing the efficiency of petroleum exploration.

scholarly journals Encapsulated NOLA™ Fit 5500 Lactase—An Economically Beneficial Way to Obtain Lactose-Free Milk at Low Temperature

Catalysts ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 527
Author(s):  
Katarzyna Czyzewska ◽  
Anna Trusek
Keyword(s):  
Low Temperature ◽  
Storage Temperature ◽  
Competitive Inhibition ◽  
Caloric Content ◽  
Substrate Diffusion ◽  
Galactose Inhibition ◽  
The Subject ◽  
And Storage ◽  
Food Processes ◽  
Hydrolysis Of

The current requirements of industrial biocatalysis are related to economically beneficial and environmentally friendly processes. Such a strategy engages low-temperature reactions. The presented approach is essential, especially in food processes, where temperature affects the quality and nutritional value foodstuffs. The subject of the study is the hydrolysis of lactose with the commercial lactase NOLA™ Fit 5500 (NOLA). The complete decomposition of lactose into two monosaccharides gives a sweeter product, recommended for lactose intolerant people and those controlling a product’s caloric content. The hydrolysis reaction was performed at 15 °C, which is related to milk transportation and storage temperature. The enzyme showed activity over the entire range of substrate concentrations (up to 55 g/L lactose). For reusability and easy isolation, the enzyme was encapsulated in a sodium alginate network. Its stability allows carrying out six cycles of the complete hydrolysis of lactose to monosaccharides, lasting from two to four hours. During the study, the kinetic description of native and encapsulated NOLA was conducted. As a result, the model of competitive galactose inhibition and glucose mixed influence (competitive inhibition and activation) was proposed. The capsule size does not influence the reaction rate; thus, the substrate diffusion into capsules can be omitted from the process description. The prepared 4 mm capsules are easy to separate between cycles, e.g., using sieves.

scholarly journals Decoupled evolution of soft and hard substrate communities during the Cambrian Explosion and Great Ordovician Biodiversification Event

2016 ◽  
Vol 113 (25) ◽  
pp. 6945-6948 ◽  
Author(s):  
Luis A. Buatois ◽  
Maria G. Mángano ◽  
Ricardo A. Olea ◽  
Mark A. Wilson
Keyword(s):  
Late Ordovician ◽  
Hard Substrate ◽  
Cambrian Explosion ◽  
Early Cambrian ◽  
Continuous Increase ◽  
Late Cambrian ◽  
Unconsolidated Sediment ◽  
Underlying Causes ◽  
Hard Substrates ◽  
Shed Light

Contrasts between the Cambrian Explosion (CE) and the Great Ordovician Biodiversification Event (GOBE) have long been recognized. Whereas the vast majority of body plans were established as a result of the CE, taxonomic increases during the GOBE were manifested at lower taxonomic levels. Assessing changes of ichnodiversity and ichnodisparity as a result of these two evolutionary events may shed light on the dynamics of both radiations. The early Cambrian (series 1 and 2) displayed a dramatic increase in ichnodiversity and ichnodisparity in softground communities. In contrast to this evolutionary explosion in bioturbation structures, only a few Cambrian bioerosion structures are known. After the middle to late Cambrian diversity plateau, ichnodiversity in softground communities shows a continuous increase during the Ordovician in both shallow- and deep-marine environments. This Ordovician increase in bioturbation diversity was not paralleled by an equally significant increase in ichnodisparity as it was during the CE. However, hard substrate communities were significantly different during the GOBE, with an increase in ichnodiversity and ichnodisparity. Innovations in macrobioerosion clearly lagged behind animal–substrate interactions in unconsolidated sediment. The underlying causes of this evolutionary decoupling are unclear but may have involved three interrelated factors: (i) a Middle to Late Ordovician increase in available hard substrates for bioerosion, (ii) increased predation, and (iii) higher energetic requirements for bioerosion compared with bioturbation.

scholarly journals Children of Heaven

2019 ◽  
Vol 5 (2) ◽  
Author(s):  
Olenka Kawchuk
Keyword(s):  
Low Temperature ◽  
South America ◽  
Geographic Origin ◽  
High Elevation ◽  
Human Sacrifice ◽  
Inca Empire ◽  
Pathological Conditions ◽  
The World ◽  
The Subject ◽  
Ritual Process

Ruling over western South America for nearly 100 years, the Inca Empire was one of many global cultures that practiced human sacrifice, though few other rituals of human sacrifice are as captivating as the Inca child sacrifice of capacocha. Capacocha children were chosen to be representatives of the Inca people in the afterlife. As such, they were afforded an elevated position in society before their death. Following their selection, children would undergo a year-long pilgrimage terminating at a mountain top shrine where they would be killed. As a result of the low temperature and oxygen levels present at such a high elevation, the bodies of capacocha children were protected against decomposition, creating some of the best-preserved natural mummies in the world. These mummies have been the subject of numerous bioarchaeological analyses to determine their age, sex, geographic origin, pathological conditions, diet, and cause of death. Beyond these, however, the mummies present a unique opportunity to study how the capacocha ritual process — including the sudden ascension in status — manifested itself on the children's bodies. This paper aims to review the bioarchaeological data garnered from the mummies in order to reconstruct the experience of a child chosen for capacocha. Results suggest higher variability between children selected for capacocha than was originally outlined by Spanish chroniclers.

scholarly journals 100 nm-Gap Fingers Dielectrophoresis Functionalized MOX Gas Sensor Array for Low Temperature VOCs Detection

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 1027
Author(s):  
Luca Francioso ◽  
Pasquale Creti ◽  
Maria Concetta Martucci ◽  
Simonetta Capone ◽  
Antonietta Taurino ◽  
...  
Keyword(s):  
Low Temperature ◽  
Gas Sensor ◽  
Sensor Array ◽  
Gas Sensing ◽  
Enhanced Sensitivity ◽  
Sno2 Nanocrystals ◽  
Gas Sensor Array ◽  
Order Of Magnitude ◽  
Nanogap Electrodes ◽  
Average Size

Present work reports the fabrication process and functional gas sensing tests of a 100 nm-gap fingers DiElectroPhoresis (DEP) functionalized MOX (Metal OXide) gas sensor array for VOCs detection at low temperature. The Internet of Things (IoT) scenario applications of the chemical sensing-enabled mobiles or connected devices are many ranging from indoor air quality to novel breath analyser for personal healthcare monitoring. However, the commercial MOX gas sensors operate at moderate temperatures (200–400 °C) [1], and this limits the mobile and wearable gadgets market penetration. Nanogap devices may represent the alternative devices with enhanced sensitivity even at low or room temperature. A nanogap electrodes MOX gas sensor array functionalized with 5 nm average size SnO2 nanocrystals with positive dielectrophoresis technique is presented. The single sensor active area is 4 × 4 µm2. The devices exhibited about 1 order of magnitude response at 100 °C to 150 ppm of acetone.

Low Temperature Photoluminescence Studies of Narrow Bandgap Gaassbn Quantum Wells on GaAs

2002 ◽  
Vol 744 ◽  
Author(s):  
K.E. Waldrip ◽  
E.D. Jones ◽  
N.A. Modine ◽  
F. Jalali ◽  
J.F. Klem ◽  
...  
Keyword(s):  
Low Temperature ◽  
Quantum Wells ◽  
Band Gap ◽  
First Principles ◽  
Structure Calculation ◽  
Ex Situ ◽  
Band Structure Calculation ◽  
Narrow Bandgap ◽  
Order Of Magnitude ◽  
Photoluminescence Studies

We present low-temperature (T = 4K) photoluminescence studies of the effect of adding nitrogen to 6-nm-wide single-strained GaAsSb quantum wells on GaAs. The samples were grown by both MBE and MOCVD tech-niques. The nominal Sb concentration is about 30%. Adding about 1 to 2% N drastically reduced the bandgap energies from 1 to 0.75 eV, or 1.20 to 1.64 μm. Upon performing ex situ rapid thermal anneals, 825°C for 10s, the band gap energies as well as the photoluminescence intensities increased. The intensities increased by an order of magnitude for the annealed samples and the band gap energies increased by about 50 - 100 meV, depending on growth temperatures. The photoluminescence linewidths tended to decrease upon annealing. Preliminary results of a first-principles band structure calculation for the GaAsSbN system are also presented.

The Antrim–Galway Line: a resolution of the Highland Border Fault enigma of the Caledonides of Britain and Ireland

1995 ◽  
Vol 132 (2) ◽  
pp. 171-184 ◽  
Author(s):  
P. D. Ryan ◽  
N. J. Soper ◽  
D. B. Snyder ◽  
R. W. England ◽  
D. H. W. Hutton
Keyword(s):  
Deep Structure ◽  
Sedimentary Basins ◽  
Strike Slip ◽  
Late Ordovician ◽  
Magnetic Data ◽  
The South ◽  
Early Devonian ◽  
Border Fault ◽  
Western Ireland

AbstractThe westward continuation of the Highland Border fault of Scotland (HBFZ) into Ireland is problematic. It is widely thought to follow a pronounced magnetic and gravity lineament, the Fair Head-Clew Bay Line (FCL). The advantage of this interpretation is that it places all the Ordovician ophiolitic complexes and associated sedimentary basins to the south of the FCL, which would represent the contact between Laurentia and the outboard terranes. Its main shortcomings are that both the deep structure and timing of strike-slip are different on the HBFZ and FCL. In Ireland the FCL is a north-dipping feature that can be traced to the Moho on BIRPS profiles, while the HBFZ has no such signature. Terrane amalgamation in western Ireland was completed by the late Ordovician, while in Scotland the Midland Valley terrane did not finally dock until the early Devonian. These considerations suggest that in western Ireland a branch of the HBFZ exists, which was active in post-Ordovician time and must lie south of Connemara. An examination of Irish geological, geophysical and image-processed magnetic data shows that a profound lineament can be traced from Antrim to Galway Bay (the Antrim–Galway Line). Stitching plutons date movement on it as pre-405 Ma. We propose that the Antrim–Galway Line represents the continuation of the Scottish HBFZ, while the FCL is a preserved Ordovician splay of the HBFZ system whose northdipping geometry is a product of Ordovician collapse of the orogen in western Ireland.

Morphology Control, Dopant Incorporation, and Selective Epitaxial Growth of 4H-SiC at Low Temperatures Using CH3Cl Growth Precursor

2006 ◽  
Vol 911 ◽  
Author(s):  
Yaroslav Koshka ◽  
Bharat Krishnan ◽  
Huang-De Lin ◽  
Galyna Melnychuk
Keyword(s):  
Growth Rate ◽  
Low Temperature ◽  
Epitaxial Growth ◽  
Growth Surface ◽  
Epitaxial Layers ◽  
Selective Epitaxial Growth ◽  
Dopant Incorporation ◽  
Nitrogen Donor ◽  
Order Of Magnitude ◽  
Silicon Vapor

AbstractLow-temperature homoepitaxial growth of 4H-SiC using halo-carbon precursors was further investigated to address the problems limiting increase of the growth rate of the defect-free epilayers at growth temperatures below 1300°C. Enhanced etching of Si clusters in the gas phase was achieved by adding HCl during the low-temperature growth. The effective Si/C ratio above the growth surface was increased as a result of reduced depletion of silicon vapor species by cluster condensation, which resulted in drastically improved epilayer morphology and significant increase of the growth rate. An intentional insitu nitrogen doping of epitaxial layers during 1300°C growth on Si and C faces revealed more than an order of magnitude higher nitrogen donor incorporation in the C-face epitaxial layers. Finally, a feasibility of selective epitaxial growth using low-temperature masking materials such as SiO2 was demonstrated.

Nanoindentation and adhesion of sol-gel-derived hard coatings on polyester

2000 ◽  
Vol 15 (1) ◽  
pp. 148-154 ◽  
Author(s):  
C. M. Chan ◽  
G. Z. Cao ◽  
H. Fong ◽  
M. Sarikaya ◽  
T. Robinson ◽  
...  
Keyword(s):  
Low Temperature ◽  
Transition Metal Oxides ◽  
Sol Gel ◽  
Surface Hardness ◽  
Hard Coatings ◽  
Silica Network ◽  
Plastic Surface ◽  
Order Of Magnitude ◽  
Oxygen Plasma Etching ◽  
Optical And Mechanical Properties

We investigated sol-gel-derived silica-based hard coatings on modified polyester substrates. The silica network was modified by incorporating an organic component and adding transition metal oxides. These modifications resulted in tailored thermal, optical, and mechanical properties of the coatings. Various low-temperature densification techniques were studied including sol-preparation procedure, enhanced solvent evaporation, ultraviolet irradiation, and low-temperature heating (below 150 °C). Oxygen plasma etching was applied to improve the adhesion of the sol-gel coatings on the plastic surface. Nanoindentation analysis revealed that the coatings have a surface hardness up to 2.5 ± 0.27 GPa and an elastic modulus up to 13.6 ± 0.4 GPa, approximately an order of magnitude higher than that of the plastic surface.

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