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Foodborne Illness
Published in Gary S. Moore, Kathleen A. Bell, Living with the Earth, 2018
Gary S. Moore, Kathleen A. Bell
Another important characteristic useful in identifying bacteria is the ability to grow in the presence or absence of oxygen. Aerobic bacteria require oxygen for growth, while the growth of anaerobes such as Clostridium is inhibited by the presence of oxygen (Figure 8.12). Some organisms, such as Campylobacter, are microaerophiles, which require low concentrations of oxygen for growth. If the anaerobe Clostridium botulinum is suspected, the investigator might search for endospores, which are structures produced during the life cycle of certain bacteria (Figure 8.13). Endospores can withstand extreme heat, harsh chemicals, and are very difficult to destroy. The dehydrated spore consists of bacterial DNA, a little RNA, some enzymes, and several layers around the spore including a thick protein spore coat that confers resistance to harsh chemicals. The spore cytoplasm also contains dipicolinic acid that forms a complex with calcium. The dipicolinic acid is a major factor in the heat resistance of spores and is essential for later resuming metabolic functions. Aside from the characteristics mentioned earlier, several other factors such as motility, lactose fermentation, or growth on a specific medium are properties that aid in the identification of bacteria.
Pyridine Polyaminocarboxylate Ligands for Use as Actinide-selective Holdback Reagents in Simplified TALSPEAK-like Extraction Systems
Published in Solvent Extraction and Ion Exchange, 2020
Nicolas E. F. Uhnak, Kenneth L. Nash
To synthesize tetraethyl 2,2ʹ,2ʹ’,2ʹ’’-((pyridine-2,6-dicarbonyl)bis(azanetriyl))tetraacetate (TEIDA2DPA), solid dipicolinic acid (DPA) (1.0 g 5 mmol) was added to 10 mL of neat SOCl2 and refluxed for 2 h; unreacted SOCl2 was removed by vacuum distillation. Methylene chloride was added to the remaining solid and the mixture allowed to stir under Ar. To this solution, 2.1 eq of diethyl iminodiacetate was added dropwise and allowed to stir for 6 h at room temperature. The organic phase was washed with 3 contacts of saturated aqueous KHCO3 solution followed by 3 washes with water and evaporated to yield a light-yellow oil. The oil was purified using a Teledyne ISCO Combiflash auto flash chromatography apparatus using a gradient of ethyl acetate in hexane; collecting 2.56 g of a colorless oil, an 84% yield. This oil was dissolved in a solution of 1:1 ethanol/water containing 8 eq of NaOH and refluxed for 3 h. Subsequently, the liquid was evaporated leaving a white solid sodium form of the amide IDA2DPA. The solid was stored under high vacuum. The yield on the conversion to a sodium salt was 96%, producing 2.34 g of the final product, a net yield of 81%.
Heavy metal complexes of 4-chlorodipicolinic acid - structural, spectral and thermal correlations
Published in Journal of Coordination Chemistry, 2019
Z. Vargová, M. Almáši, R. Gyepes, R. Vetráková
Moreover, H2PDA-Cl and other 4-substituted analogues, like chelators, were used for enhancement of terbium(III) and europium(III) complexes luminescence. Because of the ease which functional groups can be placed at the 4 position of dipicolinic acid, and the efficiency with which dipicolinic acid sensitizes lanthanide ion emission in aqueous solution, compounds of the type 4-X-dipicolinic acid represent attractive intermediates for formation of lanthanide energy transfer complexes with long emission lifetimes. In the case of Tb(III) complexes, maximum emission intensities were in the order: X = NH2 > NHAc > OH > H > Cl > Br and measurements of emission decay kinetics revealed lifetimes of 1.0–2.0 ms [13]. However, the opposite trend was observed for Eu(III) complexes luminescence sensitization finding: X = Cl > H > OH [14] and the Eu(III) luminescence lifetime varied from 1.16 to 2.90 ms.
Crystal structure, NMR and catalytic properties of a bis-peroxovanadium [NH4][VO(O2)2(mpa)]·H2O
Published in Journal of Coordination Chemistry, 2019
Ping Chen, Shaowei Zhang, Jie Zhang, Wen Xia, Xianyong Yu
Ligands containing pyridine ring, such as 2-(1H-pyrazol-1-yl)pyridine-4-carboxylic acid [15], dipicolinic acid [16], 2-pyridine carboxaldehyde [17], N-substituted 2-iminomethylpyridine [18], 2-(aminomethyl) pyridine [19], 2,6-bis(1H-benzotriazol-1-ylmethyl) pyridine [20] are key building blocks and have already been explored to form many transition metal complexes. On the other hand, the classic heteroligands in peroxidovanadium complexes are N,N- or N,O-like ligands which contain pyridine, imdazole, or amide building blocks [21]. Based on the above considerations, as a continuation work, 4-methoxypicolinamide containing pyridine and amide group (mpa) (Scheme 1) was selected to construct peroxovanadium compounds. As a result, a new peroxovanadium complex [NH4][VO(O2)2(mpa)]·H2O (1) was synthesized through coordination of NH4VO3/H2O2/mpa in aqueous solution under physiological conditions. The structure of [NH4][VO(O2)2(mpa)]·H2O was characterized by NMR and single-crystal X-ray diffraction.