On the benefits of rubbing salt in the cut: self-healing of saloplastic PAA/PAH compact polyelectrolyte complexes.

The inherent room temperature mending and self-healing properties of saloplastic PAA/PAH CoPECs are studied. After ultracentrifugation of PAA/PAH polyelectrolyte complexes, tough, elastic materials are obtained that undergo self-healing facilitated by salt. At intermediate salt concentrations the CoPECs remain elastic enough to recover their original shape while the chains are mobile enough to repair the cut, thus leading to actual self-healing behavior.journal articleresearch support, non-u.s. gov'tresearch support, u.s. gov't, non-p.h.s.2014 Apr 232014 01 29importe

Accounting for circularity

The circular economy envisages a closed-loop system of production and consumption where waste becomes a resource, reducing the environmental impacts associated with today’s linear economy. Although a deceptively simple idea in theory, a shift from a linear to circular system will require significant reorganisation of society, reinforcing the need for cooperative business models: because no organisation can become circular on its own. From an accounting perspective, the network requirements of a circular economy raise questions about what should society account for within the circular economy? How can we account for cooperative ventures between organisations? and who accounts within these networked systems? In this chapter, we begin to address some of these questions. Academic interest in the circular economy has increased significantly in recent years, and we begin the chapter by exploring interdisciplinary scholarship in circular economy, identifying key concepts and tools for organisation level analysis. We then frame the circular economy as an interest for accountants, focusing on the particular accounting challenges posed by circular systems of resource use. We argue that existing tools and accounting practices fail to meet the level of cooperation required to account for the circular economy at a networked level. Drawing on a case study on an agricultural cooperative in France, we offer some insights into how these accounting challenges emerge and impact upon circular economy projects. We conclude the chapter by offering examples for potential future research which investigates collective accounting practices for multiple organisations

Determination of the natural abundance delta N-15 of taurine by gas chromatography-isotope ratio measurement mass spectrometry

The measurement of the nitrogen isotope ratio of taurine (2-aminoethanesulphonic acid) in biological samples has a large number of potential applications. Taurine is a small water-soluble molecule which is notoriously difficult to analyze due to its polarity and functionality. A method is described which allows the determination of the natural abundance delta N-15 values of taurine and structural analogues, such as 3-amino-1-propanesulphonic acid (APSA), by isotope ratio mass spectrometry interfaced to gas chromatography (GC-irm-MS). The one-step protocol exploits the simultaneous derivatization of both functionalities of these aminosulphonic acids by reaction with triethylortho-acetate (TEOA). Conditions have been established which ensure quantitative reaction thus avoiding any nitrogen isotope fractionation during derivatization and workup. The differences in the delta N-15 values of derivatized and non-derivatized taurine and APSA all fall within the working range of 0.4 parts per thousand (-0.02 to 0.39 parts per thousand). When applied to four sources of taurine with various delta N-15 values, the method achieved excellent reproducibility and accuracy. The optimized method enables the determination of the natural abundance delta N-15 values of taurine over the concentration range 1.5-7.84 mu mol.mL(-1) in samples of biological origin. Copyright (C) 2010 John Wiley & Sons, Ltd

Human baby hair amino acid natural abundance N-15-isotope values are not related to the N-15-isotope values of amino acids in mother's breast-milk protein (vol 45, pg 1365, 2017)

International audienc

Simultaneous determination of natural-abundance 15N values and quantities of individual amino acids in proteins from milk of lactating women and from infant hair using gas chromatography/isotope ratio mass spectrometry

International audienceRATIONALE In isotope tracer experiments used in nutritional studies, it is frequently desirable both to determine the 15N/14N ratios of target compounds and to quantify these compounds. This report shows how this can be achieved in a single chromatographic run for protein amino acids using an isotope ratio mass spectrometer. METHODS Protein hydrolysis by acidic digestion was used to release amino acids, which were then derivatized as their N-pivaloyl-O-isopropyl esters. Suitable conditions for sample preparation were established for both hair and milk proteins. The N-pivaloyl-O-isopropyl esters of amino acids were separated by gas chromatography (GC) on a 60m ZB-WAX column linked via a combustion interface to an isotope ratio mass spectrometer. The 15N/14N ratios were obtained from the m/z 28, 29 and 30 peak intensities and the quantities from the Area All (Vs) integrated peak areas. RESULTS It is shown from a five-point calibration curve that both parameters can be measured reliably within the range of 1.0 to 2.0mg/mL for the major amino acids derived from the hydrolysis of human maternal milk or hair samples. The method was validated in terms of inter-day and inter-user repeatability for both parameters for 14 amino acids. The amino acid percentage composition showed a good correlation with literature values. The method was applied to determine the variability in a population of lactating mothers and their infants. CONCLUSIONS It has been established that 15N values can be simultaneously determined for a complex mixture of amino acids at variable concentrations. It is shown that the percentage composition obtained correlates well with that obtained by calculation from the protein composition or from literature values. This procedure should provide a significant saving in analysis time, especially in those cases where the GC run-time is necessarily long. It allows the satisfactory determination of the variation within a sample population. Copyright (c) 2013 John Wiley & Sons, Ltd

New triterpenoid saponin from the stems of Albizia adianthifolia (Schumach.) W.Wight

As part of our continuing study of apoptosis-inducing saponins from CameroonianAlbiziagenus, one new triterpenoid saponin, named adianthifolioside J (1), together with the known gummiferaoside E (2), were isolated fromAlbizia adianthifoliastems. The structure of the new saponin (1), was established on the basis of extensive analysis of 1 D and 2 D NMR (H-1-,C-13-NMR, DEPT, COSY, TOCSY, NOESY, HSQC, HSQC-TOCSY and HMBC) and HRESIMS experiments, and by chemical evidence as 3-O-[beta-D-xylopyranosyl-(1 -> 2)-beta-D-fucopyranosyl-(1 -> 6)-beta-D-glucopyranosyl]-21-O-{(2E,6S)-2-(hydroxymethyl)-6-methyl-6-O-{4-O-[(2E,6S)-2,6-dimethyl-6-O-(beta-D-quinovopyranosyl)octa-2,7-dienoyl]-(beta-D-quinovopyranosyl)octa-2,7-dienoyl]}acacic acid-28-O-beta-D-glucopyranosyl-(1 -> 3)-[5-O-acetyl-alpha-L-arabinofuranosyl-(1 -> 4)]-alpha-L-rhamnopyranosyl-(1 -> 2)-beta-D-glucopyranosyl ester (1).The pro-apoptotic activity of the new isolated saponin1was evaluated, using Annexin V-FITC binding assay, on the A431 human epidermoid cancer cell. The result showed that adianthifolioside J (1) displayed weak pro-apoptotic activity

Triterpenoid saponins from the stem barks of Chytranthus klaineanus Radlk. ex Engl

In our continuing studies on saponins from Cameroonian medicinal plants, phytochemical investigation of Chytranthus klaineanus stem barks led to the isolation of three new oleanane-type saponins, named Klaineanosides A-C(1-3). Their structures were established by extensive analysis of their spectral data, mainly 1D(H-1, C-13 NMR, and DEPT) and 2D (COSY, HSQC, NOESY, HSQC-TOCSY, and HMBC) NMR experiments, and mass spectrometry as 3-O-beta-D-glucopyranosyl-(1 -> 3)-beta-D-xylopyranosyl-(1 -> 4)[-beta-D-xylopyranosyl(1 -> 3)-beta-D-xylopyranosyl(1 -> 3)-alpha-L-rhamnopyranosyl-(1 -> 2)]-alpha-L-arabinopyranosylhederagenin(1), 3-O-beta-D-glucopyr-anosyl-(1 -> 3)-beta-D-xylopyranosyl-(1 -> 4)[ beta-D-xylopyranosyl(1 -> 3)-alpha-L-rhamnopyranosyl-(1 -> 2)]-alpha-L-arabinopyr-anosylhederagenin(2), and 3-O-beta-D-xylopyranosyl(1 -> 4)-beta-D-glucopyranosyl-(1 -> 3)-alpha-L-rhamnopyranosyl-(1 -> 2)-alpha-L-arabinopyranosylhederagenin(3). These triterpene saponins 1-3 have hederagenin as aglycone with a-(3)Rha-(2)Ara-(3)hederagenin oligosaccharidic sequence usually found in Sapindaceae family

Antiplasmodial sesquiterpenes from the seeds of Salacia longipes var. camerunensis

Mba'ning BM, Lenta BN, Noungoue DT, et al. Antiplasmodial sesquiterpenes from the seeds of Salacia longipes var. camerunensis. Phytochemistry. 2013;96:347-352.Phytochemical investigation of the seeds of Salacia longipes var. camerunensis led to the isolation of four sesquiterpenoid derivatives, salaterpene A (1) (1 alpha,2 beta,8 beta-triacetoxy-6 beta,9 beta-dibenzoyloxy-4 beta-hydroxy-dihydro-beta-agarofuran), salaterpene B (2) (1 alpha,2 beta,8 beta-triacetoxy-9 beta-benzoyloxy-6 beta-cinnamoyloxy-4 beta-hydroxy-dihydro-beta-agarofuran), salaterpene C (3) (1 alpha,2 beta-diacetoxy-6 beta,9 beta-dibenzoyloxy-4 beta-hydroxy-dihydro-beta-agarofuran) and salaterpene D (4) (2 beta-acetoxy-1 alpha,6 beta-dibenzoyloxy-4 beta-hydroxy-9 beta-nicotinoyloxy-dihydro-beta-agarofuran) together with two known compounds (5 and 6). The structures of the compounds were established by means of NMR spectroscopy. Compounds 1-4 and 6 were tested in vitro for their antiplasmodial activity against Plasmodium falciparum chloroquine-resistant strain W2. All the tested compounds exhibited a moderate potency with IC50 below 2.7 mu M. (C) 2013 Elsevier Ltd. All rights reserved