Determining and improving the analytical blank for radiocarbon analyses of small foraminifera samples using MICADAS and the gas interface system

<p>Foraminifera isolated from deep-sea sediments are among the most common materials in AMS radiocarbon analysis. These results are used to determine accurate age models for sediment sequences as well as to detect changes in deep-sea ventilation. Often, only small numbers of (monospecific) foraminifera shells can be isolated, in particular when studying benthic species in sediments from the polar regions. Therefore, these samples are often analyzed as CO<sub>2</sub> gas using MICADAS instruments, and the method can typically be used for samples of up to around 40 ka in age. For reliable results, an accurate determination and minimization of processing blanks is required.</p><p>Processing blanks for foraminifera samples may in part derive from acid hydrolysis of the carbonates. It has, however, been shown that contamination of the carbonate fossils, mainly from atmospheric CO<sub>2</sub> adsorbed on the porous surfaces of foraminifera, is the largest source of blank found in foraminifera samples. The removal of such contamination has been attempted by various leaching methods, which come at the risk of introducing additional contaminations. Alternatively, blank correction of AMS results may be achieved using fossil foraminifera from ancient deposits much beyond the range of the radiocarbon method.</p><p>Here we report results of a systematic test comparing the F<sup>14</sup>C levels obtained for fossil (>130 ka) and sub-modern monospecific planktic and benthic foraminifera samples using different blank correction approaches. Specifically, we compare leaching with dilute hydrochloric acid, blank correction relative to a leached and an un-leached fossil foraminifera standard, and blank correction relative to the IAEA-C1 certified carbonate standard. </p>

Salts of Sulfated Oleic Acid Amides as Acid Corrosion Inhibitors

This work is a continuation in a series of studies on the preparation of acid corrosion inhibitors based on carboxylic acids. A method of synthesis of acid corrosion inhibitors based on oleic acid amides has been developed. Several syntheses have been carried out to increase its inhibitory properties. The substances were obtained in several stages. At the first stage, amino alcohols were added to the ОA, then the resulting compounds were sulfonated with sulfuric acid. To expand the field of various inhibitors, reactions with bases are produced. As a result, salts of sulfated amides of oleic acid synthesized with amino nitrates, sulfuric acid and aqueous solutions of bases were formed. To establish the effectiveness of the compounds obtained, the protective ability in dilute hydrochloric acid was evaluated. It is established that some of the obtained substances exhibit the corresponding properties of inhibitors. In this case, the most effective is the ammonium salt of sulfated diethanolamide oleic acid.

Quaternized Chitosan Nanoparticles in Vaccine Applications

Different natural and synthetic biodegradable polymers have been used in vaccine formulations as adjuvant and delivery system but have faced various limitations. Chitosan is a new delivery system with the potential to improve development of nano vaccines and drugs. However, chitosan is only soluble in acidic solutions of low concentration inorganic acids such as dilute acetic acid and dilute hydrochloric acid and in pure organic solvents, which greatly limits its application. Chemical modification of chitosan is an important way to improve its weak solubility. Quaternized chitosan not only retains the excellent properties of chitosan, but also improves its water solubility for a wider application. Recently, quaternized chitosan nanoparticles have been widely used in biomedical field. This review focuses on some quaternized chitosan nanoparticles, and points out the advantages and research direction of quaternized chitosan nanoparticles. As shown by the applications of quaternized chitosan nanoparticles as adjuvant and delivery carrier in vaccines, quaternized chitosan nanoparticles have promising potential in application for the development of nano vaccines in the future.

Development and characteristics of a new certified reference material for landfill cover soil analysis with extraction using dilute hydrochloric acid

A new environmental certified reference material (CRM) has been developed by the National Institute for Environmental Studies (NIES) to support research and development studies on trace heavy metals in landfill cover soils.

The Salt Makers

This chapter looks at the elements from the penultimate group of the periodic table—the halogens (‘salt-formers’). We shall see that the first of these elements was discovered by Scheele during his investigations of the mineral pyrolusite. Lavoisier knew of the element but he failed to recognize it as such since he was convinced the gas had to contain oxygen and so must be a compound. It was left to Davy to prove that this was not so, which led to the English chemist naming this element that had been discovered (but not properly named) over thirty years before by the great Scheele. Davy’s choice was to influence the names given to all the members of this group, including the most recent member named in 2016. There are three common acids known as mineral acids, since they may all be obtained by heating combinations of certain minerals. Their modern names are nitric acid, sulfuric acid, and hydrochloric acid. Of these three, hydrochloric was probably the last to be discovered. Nitric and sulfuric acids were obtained in the thirteenth or early fourteenth centuries, but the earliest unambiguous preparation of relatively pure hydrochloric acid is from a hundred years later, in a manuscript from Bologna which translates as Secrets for Colour. It gives a curious recipe for a water to soften bones: ‘Take common salt and Roman vitriol in equal quantities, and grind them very well together; then distil them through an alembic, and keep the distilled water in a vessel well closed.’ As we saw in Chapter 3, ‘Roman vitriol’ is a hydrated metal sulfate, probably iron or copper sulfate; its mixture with salt, when heated, produces water and hydrogen chloride, which together form the acid solution. Later texts from the sixteenth and seventeenth centuries include similar methods to prepare this so-called spirit of salt, or ‘oyle of salt’. The first mentioned use, to soften bones, is indeed best achieved with hydrochloric acid, which readily dissolves the minerals from bone to leave only the organic matter largely intact. Leave a chicken bone in dilute hydrochloric acid for a few hours, and it may easily be bent without breaking.