14C Dating of Fire-Damaged Mortars from Medieval Finland

This study focuses on radiocarbon dating of mortars that have withstood city fires and display visible fire damage effects. Some fire-damaged and undamaged original Medieval mortars from the same site have also been tested. The mortars were heated at different temperatures and then analyzed using the same preparation procedures as in 14C dating of mortars to see what kind of changes the heating would introduce to the mineralogy, chemistry, and the carbon and oxygen isotope ratios. We found that decarbonation during heating starts at ∼600 ° and recarbonation starts as soon as the temperature drops. Already after a few days, most of the lost CO2 has been replaced with atmospheric CO2. The renewed carbonates are readily soluble in the acid hydrolysis process and their carbon and oxygen isotopes have a light signature. Fire-damaged historical mortars display the same features. If a long time has elapsed between hardening of the original mortar and the fire, the new carbonates have 14C concentrations that point to the fire event rather than to the building event. In several cases, the fire-damaged mortars have an easily soluble carbonate fraction with a 14C age that could be related to a major fire event, but still most of the soluble carbonate yields a 14C age that seems like a reasonable age for the original construction.

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Stratigraphic variations in carbon and oxygen isotopes in the dolostone of the Carswell Formation (Proterozoic) of northern Saskatchewan

Canadian Journal of Earth Sciences ◽

10.1139/e89-197 ◽

1989 ◽

Vol 26 (11) ◽

pp. 2318-2326 ◽

Cited By ~ 10

Author(s):

P. I. Abell ◽

J. McClory ◽

H. E. Hendry ◽

K. L. Wheatley

Keyword(s):

Oxygen Isotope ◽

Isotope Ratios ◽

Drill Hole ◽

Carbon And Oxygen Isotopes ◽

Oxygen Isotope Ratios ◽

Nearshore Environments ◽

Carbon And Oxygen Isotope ◽

Isotopic Analyses ◽

Northern Saskatchewan ◽

Lowermost Part

Petrographic and stable isotopic analyses of stromatolitic sediments deposited in nearshore environments provides us with some of the best information available on ancient environments. Diamond drill hole CAR 58 penetrated 110 m of sediments in the lowermost part of the Proterozoic (probably Helikian age) Carswell Formation of northern Saskatchewan and gave us such an opportunity. The rocks are mainly dolostone and include, in descending order of abundance, cyanobacterial laminites, stromatolites, dolomicrites, dolorudites, breccias, and oolites. Stromatolites and Cyanobacterial laminites increase in abundance up-section, and deposition is interpreted as having taken place in conditions of increasingly restricted water circulation through time. The carbon isotope ratios vary from about −0.5 to −1.5‰ (Pee Dee Belemnite (PDB)) in the section except near the base where they assume values near −2.5‰. The oxygen isotope ratios (vs. PDB) increase from about −9.3‰ at the base to −7‰ at the top, with anomolously high values, more positive than −7‰, at two positions in the sequence. Original depositional structures and textures are still visible in most of the rocks, but gypsum has been replaced by dolomite, there has been some silicification, and original features have been obliterated by dolomite rhombs in a few samples. The upward trend to less-negative values of the oxygen isotope ratios is interpreted in terms of changing depositional environment involving a deepening but more protected basin, with increased evaporational concentration of the heavier isotope. Scatter diagrams of carbon and oxygen isotope ratios place the Carswell Formation dolomites close to the mainstream of other Proterozoic stromatolites but indicating some evaporative alterations during deposition.

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Impact of Deuteration and Temperature on Furan Ring Dynamics

Molecules ◽

10.3390/molecules26102889 ◽

2021 ◽

Vol 26 (10) ◽

pp. 2889

Author(s):

Przemyslaw Dopieralski ◽

Iryna V. Omelchenko ◽

Zdzislaw Latajka

Keyword(s):

Conformational Changes ◽

Furan Ring ◽

Computational Studies ◽

Significant Progress ◽

Dynamic Simulations ◽

Cyclic Molecules ◽

Ring Dynamics ◽

Different Temperatures ◽

Long Time ◽

Shape And Size

Despite significant progress in conformational analysis of cyclic molecules, the number of computational studies is still limited while most of that available in the literature data have been obtained long time ago with outdated methods. In present research, we have studied temperature driven conformational changes of the furan ring at three different temperatures. Additionally, the effect of deuteration on the ring dynamics is discussed; in addition, the aromaticity indices following the Bird and HOMA schemes are computed along all trajectories. Our ab initio molecular dynamic simulations revealed that deuteration has changed the furan ring dynamics and the obvious consequences; in addition, the shape and size of molecule are expected to be different.

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Mechanical and tribological properties of ice-bonded abrasive polishing tools

Proceedings of the Institution of Mechanical Engineers Part B Journal of Engineering Manufacture ◽

10.1177/0954405417708221 ◽

2017 ◽

Vol 233 (1) ◽

pp. 132-144 ◽

Cited By ~ 2

Author(s):

S Rambabu ◽

N Ramesh Babu

Keyword(s):

Wear Rate ◽

Coefficient Of Friction ◽

Tribological Properties ◽

Melting Rate ◽

Wear Behaviour ◽

Mechanical And Tribological Properties ◽

Different Temperatures ◽

Long Time ◽

Polishing Tool ◽

Hardness Coefficient

This article covers the efforts on characterising ice-bonded abrasive polishing tool in terms of the mechanical and tribological properties such as hardness, coefficient of friction, and wear rate. These studies were attempted on the tools prepared at different temperatures ranging from −10 °C to 0 °C with a view to identify the condition suitable to prepare ice-bonded abrasive polishing tool for effective polishing of Ti–6Al–4V alloy specimen. It also presents the methods adopted to determine various properties of ice-bonded abrasive polishing tool. Hardness was estimated from the measured penetration depth of cone shape indenter into the tool, coefficient of friction was determined from the change in power drawn by the motor rotating the tool mould, and wear behaviour of tool was assessed from the melting rate of the tool determined from the change in height of ice-bonded abrasive polishing tool at different stages of polishing. From the results of this study, it is clear that ice-bonded abrasive polishing tool prepared at −4 °C has possessed sufficient hardness, coefficient of friction, and reasonable wear rate suitable for polishing of Ti–6Al–4V specimens. This article also covers the details of low-temperature coolant supply unit developed to prepare the ice-bonded abrasive polishing tool at any desired temperature between 0 °C and −40 °C and thus to maintain it for a long time. Polishing studies with such ice-bonded abrasive polishing tool showed 72% improvement in finish after 90 min of polishing of Ti–6Al–4V specimen with tool, prepared at −4 °C.

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CARBON AND OXYGEN ISOTOPE RATIOS OF MARBLES FROM SOME ANCIENT QUARRIES OF WESTERN ANATOLIA AND THEIR ARCHAEOLOGICAL SIGNIFICANCE

Archaeometry ◽

10.1111/j.1475-4754.1975.tb00135.x ◽

1975 ◽

Vol 17 (2) ◽

pp. 215-219 ◽

Cited By ~ 33

Author(s):

L. MANFRA ◽

U. MASI ◽

B. TURI

Keyword(s):

Oxygen Isotope ◽

Isotope Ratios ◽

Western Anatolia ◽

Oxygen Isotope Ratios ◽

Carbon And Oxygen Isotope

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Towards SI-traceable Isotope Ratios of Greenhouse Gases

10.5194/egusphere-egu21-16568 ◽

2021 ◽

Author(s):

Lukas Flierl ◽

Javis Nwaboh ◽

Olaf Rienitz ◽

Olav Werhahn ◽

Volker Ebert

Keyword(s):

Carbon Dioxide ◽

Greenhouse Gases ◽

Isotope Ratio ◽

Isotope Ratio Mass Spectrometry ◽

Isotope Ratios ◽

Oxygen Isotope Ratios ◽

Carbon And Oxygen Isotope ◽

First Results ◽

Buoyancy Correction ◽

The Impact

The emission of greenhouse gases and the resulting global warming is one of the most important and challenging issues of the 21st century. Carbon dioxide is one of the major contributors to the greenhouse e&#64256;ect and its atmospheric abundance has growing constantly since the beginning of the industrialization. The isotope ratios n(13C)/n(12C) and n(18O)/n(16O) are important tools for studying the impact of anthropogenic CO2. Usually, isotopic compositions of CO2 are reported as &#948;-values, that express isotope ratios relative to an artifact based on a fossil calcite called VPDB. This relative VPDB scale was necessary, since absolute and SI-traceable isotope ratios of CO2 are currently not available, neither by isotope ratio mass spectrometry (IRMS) nor by optical isotope ratio spectroscopy (OIRS). In this study we present a potential way of deriving absolute carbon and oxygen isotope ratios of carbon dioxide via IRMS based on the gravimetric mixture approach. Besides practical improvements like an air buoyancy correction scheme for masses of gases, we show first results applying our method which demonstrate its feasibility, limitations, and achievable uncertainties. Also, we show the mathematics behind our approach and discuss further improvements and applications. Furthermore, we show how these absolute ratios can be used in field applications by OIRS methods including a new approach on OIRS uncertainty assessments according to the GUM. For this contribution we report on our recent results within in the European metrology research projects SIRS (16ENV06). and STELLAR (19ENV05).

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Paleoenvironmental Traces of Carbon and Oxygen Isotopes in Carbonate Rocks: An Example From Dengying Formation in Xichuan Area, Henan Province

10.21203/rs.3.rs-17072/v1 ◽

2020 ◽

Author(s):

Lan Zhang ◽

Hong Xie ◽

Qingguang Li ◽

Zhenghao Lu ◽

Yang Bai ◽

...

Keyword(s):

Oxygen Isotope ◽

Carbonate Rocks ◽

Isotope Composition ◽

Salinity Range ◽

Carbon And Oxygen Isotopes ◽

Accurate Analysis ◽

Average Value ◽

Dengying Formation ◽

Three Samples ◽

Carbon And Oxygen Isotope

Abstract The carbon and oxygen isotope composition of carbonate rocks is an important index for accurate analysis of the paleo-sea environment, which depends on Mn/Sr, δ 18 O > -10‰, correlativity of δ 13 C and δ 18 O and “age effect” of δ 18 O. This study reports carbon and oxygen isotope data of carbonate rocks from the Dengying Formation in the Xichuan area. δ 13 C values range -1.58‰ to 3.76‰, with an average value of 1.55‰, and δ 18 O values are -14.91‰ to -1.88‰, with an average value of -6.95‰. The δ 18 O values of three samples are less than -10‰, so they are excluded and taken to be correlative with the cracking of the Rodinia supercontinent during the Neoproterozoic. The paleotemperature range 7.40°C to 35.05°C, with an average value of 21.09°C. Paleo-salinity range 8.38‰ to 19.30‰, with an average value of 13.89‰. Z values range 127.80 to 135.03 and thus all exceeded 120, with an average value of 131.25. These calculations indicate that the Xichuan area had deposited marine carbonate rocks, with the hot and dry tropical monsoon climate, and a transgressive process overall during the Dengying age.

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Heat Exchanger for Bio-Digester under Thermophilic Range

Journal of Advanced College of Engineering and Management ◽

10.3126/jacem.v5i0.26691 ◽

2019 ◽

Vol 5 ◽

pp. 79-88

Author(s):

Prajwal Sapkota ◽

Laxman Poudel

Keyword(s):

Heat Exchanger ◽

Anaerobic Digestion ◽

Heat Exchangers ◽

Heating System ◽

Gas Production ◽

Cow Dung ◽

Digestion Rate ◽

Digestion Process ◽

Different Temperatures ◽

Long Time

Bio-gas has been one of the sources of renewable energy and has been used from long time. It is produced by the anaerobic digestion or decomposition of organic compounds and has different process. The digestion process is carried out by bacteria present in the waste and it is highly dependent on the bacteria which work differently on different temperatures. The rate of anaerobic digestion is highest at hemophilic temperature (55°C). Similarly, it is moderate at mesophilic temperature (35°C) and is lowest at psychrophilic (below 20°C). Thus, to attain the highest digestion rate a thermophilic heating system has beend eveloped. The heating system uses five heat exchangers to heat the influent at digester which is of 35m3 volume, to maintain temperature at 56°C. The volume of bio-gas production from this system which uses cow dung as digestingmaterial is about 28 m3 per day.

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