Preprints

Filtering by Subject: Chemistry

PREPRINT- Adsorption behavior of new theophylline-triazole based derivatives as effective corrosion inhibitors for steel in acidic medium

Araceli Espinoza-Vázquez, Francisco Javier Rodríguez-Gómez, Ivonne Karina Martínez-Cruz, et al.

Published: 2019-02-18
Subjects: Chemistry, Other Chemistry, Physical Sciences and Mathematics

The design and synthesis of a series of theophylline derivatives containing 1,2,3-triazole moieties is presented. The corrosion inhibition activities of these new triazole-theophylline compounds were evaluated by studying the corrosion of API 5L X52 steel in 1 M HCl media. The results showed that an increase in the concentration of the theophylline-triazole derivatives also increases the charge [...]

POSTPRINT-Adsorption and corrosion inhibition behavior of new theophylline-triazole based derivatives for steel in acidic medium

Araceli Espinoza-Vázquez, Francisco Javier Rodríguez-Gómez, Ivonne Karina Martínez-Cruz, et al.

Published: 2019-02-11
Subjects: Chemistry, Other Chemistry, Physical Sciences and Mathematics

The design and synthesis of a series of theophylline derivatives containing 1,2,3-triazole moieties is presented. The corrosion inhibition activities of these new triazole-theophylline compounds were evaluated by studying the corrosion of API 5L X52 steel in 1 M HCl media. The results showed that an increase in the concentration of the theophylline-triazole derivatives also increases the charge [...]

Insights into agricultural influences and weathering processes from major ion patters

Robert van Geldern, Peter Schulte, Michael Mader, et al.

Published: 2018-06-04
Subjects: Chemistry, Earth Sciences, Environmental Chemistry, Environmental Sciences, Geochemistry, Hydrology, Physical Sciences and Mathematics, Water Resource Management

Karst areas and their catchments pose a great challenge for protection because fast conduit flow results in low natural attenuation of anthropogenic contaminants. Studies of the hydrochemistry of karst sources and river solutes are an important tool for securing and managing water resources. A study of the geochemical downriver evolution of the Wiesent River and its tributaries, located in a [...]

What caused Earths largest mass extinction event? New evidence from the Permian-Triassic boundary in northeastern Utah

Benjamin Burger

Published: 2018-02-26
Subjects: Biogeochemistry, Biology, Chemistry, Earth Sciences, Environmental Chemistry, Environmental Indicators and Impact Assessment, Environmental Sciences, Geology, Life Sciences, Paleobiology, Paleontology, Physical Sciences and Mathematics, Sedimentology

The discovery of a Permian-Triassic boundary section in northeastern Utah reveals a detailed record of events that led to one of the greatest mass extinctions on the planet. From 83% to 97% of the species living on the planet went extinct during this relatively short interval of geological time, which defines the major geological boundary between the Paleozoic and Mesozoic Eras. The cause and [...]

Distributions of geohopanoids in peat: implications for the use of hopanoid-based proxies in natural archives

Gordon Neil Inglis, B. David. A. Naafs, Yanhong Zheng, et al.

Published: 2018-02-04
Subjects: Biogeochemistry, Chemistry, Earth Sciences, Environmental Sciences, Geochemistry, Other Physical Sciences and Mathematics, Physical Sciences and Mathematics

Hopanoids are pentacyclic triterpenoids produced by a wide range of bacteria. Within modern settings, hopanoids mostly occur in the biological 17β,21β(H) configuration. However, in some modern peatlands, the C31 hopane is present as the thermally-mature 17α,21β(H) stereoisomer. This has traditionally been ascribed to isomerisation at the C-17 position catalysed by the acidic environment. However, [...]

Impacts of land-use and land-cover change on stream hydrochemistry in the Cerrado and Amazon biomes

Rodolfo Luiz Bezerra Nóbrega, Alphonce C. Guzha, Gabriele Lamparter, et al.

Published: 2018-01-28
Subjects: Chemistry, Computer Sciences, Earth Sciences, Environmental Indicators and Impact Assessment, Environmental Monitoring, Environmental Sciences, Fresh Water Studies, Geography, Hydrology, Natural Resources and Conservation, Oceanography and Atmospheric Sciences and Meteorology, Physical and Environmental Geography, Physical Sciences and Mathematics, Physics, Social and Behavioral Sciences, Soil Science

Studies on the impacts of land-use and land-cover change on stream hydrochemistry in active deforestation zones of the Amazon agricultural frontier are limited and have often used low-temporal-resolution datasets. Moreover, these impacts are not concurrently assessed in well-established agricultural areas and new deforestations hotspots. We aimed to identify these impacts using an experimental [...]

Lake sediment records of persistent organic pollutants and polycyclic aromatic hydrocarbons in Southern Siberia mirror the changing fortunes of the Russian economy over the past 70 years

Jennifer K Adams, César C. Martins, Neil L. Rose, et al.

Published: 2017-12-18
Subjects: Chemistry, Ecology and Evolutionary Biology, Environmental Chemistry, Environmental Sciences, Life Sciences, Physical Sciences and Mathematics, Terrestrial and Aquatic Ecology

Persistent organic pollutants (POPs) and polycyclic aromatic hydrocarbons (PAHs) have previously been detected in the surface sediments, water, and endemic organisms of Lake Baikal, a UNESCO World Heritage Site. The Selenga River is the primary source of freshwater to Lake Baikal, and transports pollutants accumulating in the Selenga River basin to the lake. Sources of POPs and PAHs in the [...]

Recycling of archaeal biomass as a new strategy for extreme life in Dead Sea deep sediments

Camille Thomas, Vincent Grossi, Ingrid Antheaume, et al.

Published: 2017-12-15
Subjects: Biogeochemistry, Chemistry, Earth Sciences, Organic Chemistry, Physical Sciences and Mathematics

Archaea and Bacteria that inhabit the deep subsurface (known as the deep biosphere) play a prevalent role in the recycling of sedimentary organic carbon. In such environments, this process can occur over millions of years and requires microbial communities to cope with extremely limited sources of energy. Because of this scarcity, metabolic processes come at a high energetic cost, but the ways [...]

Isotopic composition (238U/235U) of some commonly used uranium reference materials

Daniel Condon, Noah McLean, Stephen R Noble, et al.

Published: 2017-11-05
Subjects: Chemistry, Cosmochemistry, Earth Sciences, Geochemistry, Inorganic Chemistry, Physical Sciences and Mathematics

We have determined 238U/235U ratios for a suite of commonly used natural (CRM 112a, SRM 950a, and HU-1) and synthetic (IRMM 184 and CRM U500) uranium reference materials by thermal ionisation mass-spectrometry (TIMS) using the IRMM 3636 233U–236U double spike to accurately correct for mass fractionation. Total uncertainty on the 238U/235U determinations is estimated to be <0.02% (2σ). These [...]

238U/235U Systematics in Terrestrial Uranium-Bearing Minerals

Joe Hiess, Daniel Condon, Noah McLean, et al.

Published: 2017-11-05
Subjects: Chemistry, Cosmochemistry, Earth Sciences, Geochemistry, Inorganic Chemistry, Physical Sciences and Mathematics

The present-day 238U/235U ratio has fundamental implications for uranium-lead geochronology and cosmochronology. A value of 137.88 has previously been considered invariant and has been used without uncertainty to calculate terrestrial mineral ages. We report high-precision 238U/235U measurements for a suite of uranium-bearing minerals from 58 samples representing a diverse range of lithologies. [...]

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