Artigos de revistas: "Small amines"

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Barham, Joshua P., e Jaspreet Kaur. "Site-Selective C(sp3)–H Functionalizations Mediated by Hydrogen Atom Transfer Reactions via α-Amino/α-Amido Radicals". Synthesis 54, n.º 06 (25 de outubro de 2021): 1461–77. http://dx.doi.org/10.1055/a-1677-6619.

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AbstractAmines and amides, as N-containing compounds, are ubiquitous in pharmaceutically-active scaffolds, natural products, agrochemicals, and peptides. Amides in nature bear a key responsibility for imparting three-dimensional structure, such as in proteins. Structural modifications to amines and amides, especially at their positions α to N, bring about profound changes in biological activity oftentimes leading to more desirable pharmacological profiles of small drug molecules. A number of recent developments in synthetic methodology for the functionalizations of amines and amides omit the need of their directing groups or pre-functionalizations, achieving direct activation of the otherwise relatively benign C(sp3)–H bonds α to N. Among these, hydrogen atom transfer (HAT) has proven a very powerful platform for the selective activation of amines and amides to their α-amino and α-amido radicals, which can then be employed to furnish C–C and C–X (X = heteroatom) bonds. The abilities to both form these radicals and control their reactivity in a site-selective manner is of utmost importance for such chemistries to witness applications in late-stage functionalization. Therefore, this review captures contemporary HAT strategies to realize chemo- and regioselective amine and amide α-C(sp3)–H functionalization, based on bond strengths, bond polarities, reversible HAT equilibria, traceless electrostatic-directing auxiliaries, and steric effects of in situ-generated HAT agents.1 Introduction2 Functionalizations of Amines3 Functionalizations of Carbamates4 Functionalizations of Amides5 Conclusion

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Johnson, Nnadikwe, Wopara Onuoha FIdelis, Onyewudiala Ibeawuchi Julius, Udechukwu Mathew Chidubem e Ewelike Asterius Dozie. "Development Design of Amine Sweetening Unit Plant of Natural Gas". International Journal for Research in Applied Science and Engineering Technology 10, n.º 9 (30 de setembro de 2022): 397–403. http://dx.doi.org/10.22214/ijraset.2022.46548.

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Abstract: In addition to reduced equipment sizes, lower circulation rates, and greater overall amine concentration, selective amines have become more popular for gas sweetening. Selective amines absorb H2S from CO2 through thermodynamic or kinetic processes. Selective amine mixtures may enable a small quantity of CO2 to remain in the treated gas. Plant capacity margins for selective amine units are frequently small. Increasing the acid gas concentration or throughput might result in sweet gas that does not fulfill CO2 specifications. Increasing the amine concentration, employing combinations of amines, and altering the lean amine temperature were explored since adding new equipment may be costly. Compared to increasing reboiler or pumping capacity, these factors need little or no extra capital.

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Li, Jin Tang, Shi Qiu, Rong Yi Chen, Chuan Hai Gan, Xue Zeng e Xue Tao Luo. "Hydrothermal Synthesis of Porous Materials Using Calcined Kaolin with Small Molecular Amine Templates". Advanced Materials Research 1025-1026 (setembro de 2014): 515–18. http://dx.doi.org/10.4028/www.scientific.net/amr.1025-1026.515.

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Three kinds of porous materials were synthesized using calcined kaolin with small molecular amine templates by hydrothermal methods. Sodium silicate was chose as silicon sources and three different amines namely acetamide, ethylenediamine and hexamethylenetetramine were chose as the organic templates. The physicochemical properties of obtained samples were characterized by X-ray diffraction, infrared spectrum and scanning electron microscopy.Crystallinity and morphology of samples were investigated. The influence of small molecular amines templates was discussed.

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Creaser, Colin S., John R. Griffiths e Brian M. Stockton. "Gas-Phase Ion Mobility Studies of Amines and Polyether/Amine Complexes Using Tandem Quadrupole Ion Trap/Ion Mobility Spectrometry". European Journal of Mass Spectrometry 6, n.º 2 (abril de 2000): 213–18. http://dx.doi.org/10.1255/ejms.339.

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The gas-phase positive ion mobility spectra of isomeric amines and polyether/amine complexes have been measured using a tandem quadrupole ion trap/ion mobility spectrometer. Ion mobilities of isomeric amines in helium, determined relative to benzene at pressures in the range 1–2 Torr, vary with the structure of the amine. The ability of quadrupole ion trap/ion mobility spectrometry to differentiate between a pharmacologically-active substance and an associated isomeric amine is demonstrated. Non-covalent complexes of cyclic and acyclic polyethers with protonated amines were generated by ion/molecule reactions in the ion trap and analysed by ion mobility spectrometry. The ion mobilities in helium may be interpreted in terms of the preferred conformations for these complexes. The use of polyether hosts as shift compounds for enhancing the relative mobilities of small amine guest ions is proposed.

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KIM, HYEONG SANG, e SUN JIN HUR. "Effect of In Vitro Human Digestion on Biogenic Amine (Tyramine) Formation in Various Fermented Sausages". Journal of Food Protection 81, n.º 3 (6 de fevereiro de 2018): 365–68. http://dx.doi.org/10.4315/0362-028x.jfp-17-372.

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ABSTRACT Biogenic amines are formed in various fermented foods by microbial amino acid decarboxylation activities, and ingestion of these amines may cause human illness. However, the effect of digestion on the biogenic amines in fermented sausages has not been studied. This study was conducted to determine the effect of in vitro human digestion with the enterobacteria Escherichia coli and Lactobacillus casei on concentrations of the biogenic amine tyramine in six types of fermented sausages. Tyramine concentration was not significantly changed until simulated digestion in the small intestine. However, tyramine concentration for all sausage samples was increased after simulated digestion in the large intestine. Addition of E. coli and L. casei dramatically increased the tyramine concentrations (P < 0.05). This result indicates that enterobacteria increase biogenic amine concentrations during human digestion.

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Liu, Wei, Yuxi Zhang, Shui Wang, Lisen Bai, Yanhui Deng e Jingzhong Tao. "Effect of Pore Size Distribution and Amination on Adsorption Capacities of Polymeric Adsorbents". Molecules 26, n.º 17 (30 de agosto de 2021): 5267. http://dx.doi.org/10.3390/molecules26175267.

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Polymeric adsorbents with different properties were synthesized via suspension polymerization. Equilibrium and kinetics experiments were then performed to verify the adsorption capacities of the resins for molecules of various sizes. The adsorption of small molecules reached equilibrium more quickly than the adsorption of large molecules. Furthermore, the resins with small pores are easy to lower their adsorption capacities for large molecules because of the pore blockage effect. After amination, the specific surface areas of the resins decreased. The average pore diameter decreased when the resin was modified with either primary or tertiary amines, but the pore diameter increased when the resin was modified with secondary amines. The phenol adsorption capacities of the amine-modified resins were reduced because of the decreased specific area. The amine-modified resins could more efficiently adsorb reactive brilliant blue 4 owing to the presence of polar functional groups.

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GARAI, G., M. T. DUEÑAS, A. IRASTORZA, P. J. MARTÍN-ÁLVAREZ e M. V. MORENO-ARRIBAS. "Biogenic Amines in Natural Ciders". Journal of Food Protection 69, n.º 12 (1 de dezembro de 2006): 3006–12. http://dx.doi.org/10.4315/0362-028x-69.12.3006.

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Biogenic amines play an important physiological role in mammals, and high amounts of some exogenous amines in human diet may contribute to a wide variety of toxic effects. These amines are commonly found in many foodstuffs, particularly in fermented products such as cheese, meat products, beer, wine, and ciders. Here, the level of biogenic amines in some natural ciders was examined. Twenty-four samples of cider purchased from commercial sources were analyzed by reverse-phase high-performance liquid chromatography and fluorescence detection after precolumn derivatization with o-phthaldialdehyde. Amine levels were variable, ranging from not detected to 23 mg/liter. The average level of total biogenic amines in ciders was 5.94 ± 8.42 mg/liter. Putrescine, histamine, and tyramine were the prevailing amines being present in 50.0, 37.5, and 33.3% of the ciders studied; very small amounts of ethylamine and phenylethylamine were observed in only one sample. Other cider parameters were analyzed to determine whether they affect the biogenic amine content in ciders, and the results were evaluated by applying cluster analysis and principal component analysis. Ciders that showed lower glycerol contents and higher amounts of 1,3-propanediol had much higher levels of histamine, tyramine, and putrescine, suggesting a high activity of lactic acid bacteria during cider making and thus the need for effective control of lactic acid bacteria.

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Ríos-García, Martiño, Berta Fernández, Jesús Rodríguez-Otero, Enrique M. Cabaleiro-Lago e Saulo A. Vázquez. "The PM6-FGC Method: Improved Corrections for Amines and Amides". Molecules 27, n.º 5 (3 de março de 2022): 1678. http://dx.doi.org/10.3390/molecules27051678.

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Recently, we reported a new approach to develop pairwise analytical corrections to improve the description of noncovalent interactions, by approximate methods of electronic structures, such as semiempirical quantum mechanical (SQM) methods. In particular, and as a proof of concept, we used the PM6 Hamiltonian and we named the method PM6-FGC, where the FGC acronym, corresponding to Functional Group Corrections, emphasizes the idea that the corrections work for specific functional groups rather than for individual atom pairs. The analytical corrections were derived from fits to B3LYP-D3/def2-TZVP (reference). PM6 interaction energy differences, evaluated for a reduced set of small bimolecular complexes, were chosen as representatives of saturated hydrocarbons, carboxylic, amine and, tentatively, amide functional groups. For the validation, the method was applied to several complexes of well-known databases, as well as to complexes of diglycine and dialanine, assuming the transferability of amine group corrections to amide groups. The PM6-FGC method showed great potential but revealed significant inaccuracies for the description of some interactions involving the –NH2 group in amines and amides, caused by the inadequate selection of the model compound used to represent these functional groups (an NH3 molecule). In this work, methylamine and acetamide are used as representatives of amine and amide groups, respectively. This new selection leads to significant improvements in the calculation of noncovalent interactions in the validation set.

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SCRUTTON, Nigel S., e Andrew R. C. RAINE. "Cation-π bonding and amino-aromatic interactions in the biomolecular recognition of substituted ammonium ligands". Biochemical Journal 319, n.º 1 (1 de outubro de 1996): 1–8. http://dx.doi.org/10.1042/bj3190001.

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Cation-π bonds and amino-aromatic interactions are known to be important contributors to protein architecture and stability, and their role in ligand-protein interactions has also been reported. Many biologically active amines contain substituted ammonium moieties, and cation-π bonding and amino-aromatic interactions often enable these molecules to associate with proteins. The role of organic cation-π bonding and amino-aromatic interactions in the recognition of small-molecule amines and peptides by proteins is an important topic for those involved in structure-based drug design, and although the number of structures determined for proteins displaying these interactions is small, general features are beginning to emerge. This review explores the role of cation-π bonding and amino-aromatic interactions in the biological molecular recognition of amine ligands. Perspectives on the design of ammonium-ligand-binding sites are also discussed.

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Katsura, Toshiya, Hiroshi Mizuuchi, Yukiya Hashimoto e Ken-Ichi Inui. "Transport of procainamide via H+/tertiary amine antiport system in rabbit intestinal brush-border membrane". American Journal of Physiology-Gastrointestinal and Liver Physiology 279, n.º 4 (1 de outubro de 2000): G799—G805. http://dx.doi.org/10.1152/ajpgi.2000.279.4.g799.

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Transport characteristics of procainamide in the brush-border membrane isolated from rabbit small intestine were studied by a rapid-filtration technique. Procainamide uptake by brush-border membrane vesicles was stimulated by an outward H+ gradient (pHin= 6.0, pHout = 7.5) against a concentration gradient (overshoot phenomenon), and this stimulation was reduced when the H+ gradient was subjected to rapid dissipation by the presence of a protonophore, FCCP. An outward H+gradient-dependent procainamide uptake was not caused by H+diffusion potential. The initial uptake of procainamide was inhibited by other tertiary amines with N-dimethyl or N-diethyl moieties in their structures, such as triethylamine, dimethylaminoethyl chloride, and diphenhydramine, but not by tetraethylammonium and thiamine. Furthermore, procainamide uptake was stimulated by preloading the vesicles with these tertiary amines ( trans-stimulation effect), indicating the existence of a specific transport system for tertiary amines. These findings indicate that procainamide transport in the intestinal brush-border membrane is mediated by the H+/tertiary amine antiport system that recognizes N-dimethyl or N-diethyl moieties in the structures of tertiary amines.

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Hutařová, Zdeňka, Vladimír Večerek e Petr Maršálek. "Biogenic amines in the meat of hunted pheasant and hare during the course of storage". Acta Veterinaria Brno 83, n.º 10 (2014): S45—S50. http://dx.doi.org/10.2754/avb201483s10s45.

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Venison is becoming more and more interesting for consumers. Although treatment procedures of hunted game differ from slaughtered livestock, the hygienic quality of game meat must still be ensured. Potential indicators of meat hygienic quality include the content of biogenic amines. The aim of the present study was to assess the content and changes of biogenic amines in the muscles of selected kinds of small game (common pheasant and brown hare) during storage, and based on the obtained results, to assess the hygienic quality of the meat. Biogenic amines (putrescine, cadaverine, histamine, tyramine, phenylethylamine, and tryptamine) in the breast and thigh muscles separated by reverse phase liquid chromatography and consequently were detected using tandem mass spectrometry. Based on the determined content of biogenic amines, both pheasant and hare meats complied with values of high quality meat. The sum of biogenic amines did not exceed the value of 5 mg/kg after 7 days at 0 °C or 7 °C in pheasant meat, and after 21 days at 0 °C or after 14 days at 7 °C in brown hare meat. The biogenic amine content and the speed of their formation in venison can be very helpful for the evaluation of both meat hygienic quality and safety of these foods during storage.

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Iwanek, Waldemar. "Complexes of resorcin[4]arene with secondary amines: synthesis, solvent influence on “in-out” structure, and theoretical calculations of non-covalent interactions". Beilstein Journal of Organic Chemistry 19 (29 de setembro de 2023): 1525–36. http://dx.doi.org/10.3762/bjoc.19.109.

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Resorcin[4]arenes (R[4]A) are macrocyclic compounds with a cavity structure. Despite a relatively small cavity, these compounds are capable of forming complexes with small organic molecules. The current paper focuses on the synthesis of complexes between R[4]A and secondary aliphatic amines (sec-amines). Through NMR spectroscopy, it was observed that “in-out” complexes are formed depending on the solvent. It was also found that the stoichiometry of the formed complexes depends on the size of the amine molecule. The automated interaction sites screening (aISS) made it possible to generate molecular ensembles of complexes. The geometry of the ensembles was first optimized with the r2scan-3c functional and, finally, the structure with the lowest energy, with the functional PBE0-D4/mTZVPP/CPCM. The Hartree–Fock plus London dispersion (HFLD) method was used for the study of non-covalent interactions (NCI). The calculations lead to the conclusion that a reduction in electrostatic interactions and an increase in exchange and dispersion interactions in CHCl3 in relation to DMSO are the driving forces behind the placement of sec-amine molecules into the R[4]A cavity and the formation of “in” type complexes.

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Os, M. Van, J. P. Dulphy e R. Baumont. "The effect of protein degradation products in grass silages on feed intake and intake behaviour in sheep". British Journal of Nutrition 73, n.º 1 (janeiro de 1995): 51–64. http://dx.doi.org/10.1079/bjn19950008.

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The effects of NH3 and amines on grass-silage intake, intake behaviour and rumen characteristics were studied in sheep. From a single sward, two direct-cut grass silages were prepared, either untreated (WAS) or with 4·51 formic acid/tonne (FAS). Four experimental diets: WAS, FAS, FAS with addition of 2·9 g NH3/kg DM (FAS + N) and FAS with 2·8 g amines/kg DM (FAS + A), were offered ad lib. once daily to four rumen-cannulated wethers in a 4 × 4 Latin square design. Daily DM intake (DMI) tended to be influenced by dietary treatment (P = 0·09). Compared with FAS, DMI was lower for WAS. Addition of NH3 did not alter DMI, whereas amine addition slightly lowered daily DMI. Reduced DMI resulted from lower intake rates during both the principal meal and the subsequent small meals. Lower initial intake rate during the principal meal suggested reduced palatability of WAS and FAS + A. Amines and NH3, however, did not influence chewing efficiency. No treatment effects were observed on total rumen pool size, DM and neutral-detergent fibre content. Furthermore, NH3, and amines did not alter rumen pH, NH3, and volatile fatty acid concentrations to the extent that they could act on chemostatic intake regulation. Amine addition, however, lowered osmolality of the rumen liquid. No treatment effects on rumen motility were observed. In conclusion, daily DMI was not reduced by the addition of NH3, suggesting that NH3per se is not the causal factor in the negative correlations between silage NH3 content and intake observed by other authors. Amines, however, tended to reduce DMI only by their effect at the oro-pharyngeal level of intake control.

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GARCÍA-GARCÍA, P., M. BRENES-BALBUENA, D. HORNERO-MÉNDEZ, A. GARCÍA-BORREGO e A. GARRIDO-FERNÁNDEZ. "Content of Biogenic Amines in Table Olives". Journal of Food Protection 63, n.º 1 (1 de janeiro de 2000): 111–16. http://dx.doi.org/10.4315/0362-028x-63.1.111.

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Content of biogenic amines in flesh and brines of table olives was determined by high-pressure liquid chromatography analysis of their benzoyl derivatives. No biogenic amines were found in the flesh of fresh fruits at any stage of ripeness. Contents of biogenic amines in Spanish-style green or stored olives increased throughout the brining period but were always higher in the former. Putrescine was the amine found in the highest concentration. Small quantities of cadaverine were found in the samples taken after 3 months of brining. This compound and histamine, tyramine, and tryptamine were also found in samples taken after 12 months. Gordal cultivar showed the highest contents, followed by Manzanilla and Hojiblanca. No relationship was found between contents of biogenic amines and lactic acid production or table olive spoilages, although zapatera olives had considerably higher amounts than those brines that had undergone a normal process. Concentrations in directly brined olives were markedly lower than contents in Spanish-style olives. With respect to partition between flesh and brine, there was equilibrium between both media in the case of Spanish-style olives, whereas the contents in directly brined olives were higher in flesh than brine.

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Kruszczak, Ewelina, e Hanna Kierzkowska-Pawlak. "CO2 Capture by Absorption in Activated Aqueous Solutions of N,N-Diethylethanoloamine". Ecological Chemistry and Engineering S 24, n.º 2 (27 de junho de 2017): 239–48. http://dx.doi.org/10.1515/eces-2017-0016.

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Abstract The CO2 absorption process using aqueous amine solutions has been the most promising technique used for the removal of CO2 from gas streams in energy sector. In recent years, many researchers tested solutions which are composed of several compounds: a slow reacting tertiary amine- and a fast amine acting as an activator. In this paper, the CO2 absorption rate in an aqueous solution of N,N-diethylethanoloamine (DEEA) and activated solutions DEEA is investigated experimentally. The activators considered are sterically hindered amines: 2-amino-2-methyl-1-propanol (AMP), 2-amino-2-methyl-1,3-propanediol (AMPD) and N-methyl-1,3-propanediamine (MAPA) from the group of polyamines. The experiments were conducted over the temperature range of 303-333 K and the total amine concentration of 2 M. From the CO2 absorption experiments into mixed aqueous solutions of DEEA and MAPA, it was found that the addition of small amounts of MAPA into aqueous DEEA solutions has a significant effect on the enhancement of the CO2 absorption rate. The application of hindered amines: AMP or AMP as activators resulted in a marginally improvement of the absorption rate of CO2.

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Stohs, Sidney J., Harry G. Preuss e Mohd Shara. "A Review of the Receptor-Binding Properties ofp-Synephrine as Related to Its Pharmacological Effects". Oxidative Medicine and Cellular Longevity 2011 (2011): 1–9. http://dx.doi.org/10.1155/2011/482973.

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Bitter orange (Citrus aurantium) extract and its primary protoalkaloidp-synephrine are used widely in weight loss/weight management and sports performance products. Because of structural similarities, the pharmacological effects ofp-synephrine are widely assumed to be similar to those of ephedrine,m-synephrine (phenylephrine), and endogenous amine neurotransmitters as norepinephrine and epinephrine. However, small structural changes result in the receptor binding characteristics of these amines that are markedly different, providing a plausible explanation for the paucity of adverse effects associated with the wide-spread consumption ofp-synephrine in the form of dietary supplements as well as in variousCitrusfoods and juices. This paper summarizes the adrenoreceptor binding characteristics ofp-synephrine relative tom-synephrine, norepinephrine, and other amines as related to the observed pharmacological effects.

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STRATTON, JAYNE E., ROVERT W. HUTKINS e STEVE L. TAYLOR. "Biogenic Amines in Cheese and other Fermented Foods: A Review". Journal of Food Protection 54, n.º 6 (1 de junho de 1991): 460–70. http://dx.doi.org/10.4315/0362-028x-54.6.460.

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The biogenic amine content of various foods has been widely studied because of their potential toxicity. Biogenic amines, such as tyramine and β-phenylethylamine, have been proposed as the initiators of hypertensive crisis in certain patients and of dietary-induced migraine. Another amine, histamine, has been implicated as the causative agent in several outbreaks of food poisoning. Histamine poisoning is a foodborne chemical intoxication resulting from the ingestion of foods containing excessive amounts of histamine. Although commonly associated with the consumption of scombroid-type fish, other foods such as cheese have also been associated with outbreaks of histamine poisoning. Fermented foods such as wine, dry sausage, sauerkraut, miso, and soy sauce can also contain histamine along with other biogenic amines. Microorganisms possessing the enzyme histidine decarboxylase, which converts histidine to histamine, are responsible for the formation of histamine in foods. One organism, Lactobacillus buchneri, may be important to the dairy industry due to its involvement in cheese-related outbreaks of histamine-poisoning. The toxicity of histamine appears to be enhanced by the presence of other biogenic amines found in foods that can inhibit histamine-metabolizing enzymes in the small intestine. Estimating the frequency of histamine poisoning is difficult because most countries do not regulate histamine levels in foods, nor do they require notification when an incident of histamine poisoning occurs. Also, because histamine poisoning closely resembles a food allergy, it may often be misdiagnosed. This review will focus on the importance of histamine and biogenic amines in cheese and other fermented foods.

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Wright, Ian. "Small animal Review". Companion Animal 27, n.º 6 (2 de junho de 2022): 102. http://dx.doi.org/10.12968/coan.2022.0017.

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Summary: This month's Small Animal Review summarises three papers on a ‘slow kill’ protocol for treating heartworm in dogs; two cases of ocular onchocercosis in UK dogs imported from Europe and the use of urine and faecal samples in measuring exposure to aromatic amines.

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Kendall, Christian G., Amanda M. Stockton, Stephen Leicht, Heather McCaig, Shirley Chung, Valerie Scott, Fang Zhong e Ying Lin. "Amine Analysis Using AlexaFluor 488 Succinimidyl Ester and Capillary Electrophoresis with Laser-Induced Fluorescence". Journal of Analytical Methods in Chemistry 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/368362.

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Fluorescent probes enable detection of otherwise nonfluorescent species via highly sensitive laser-induced fluorescence. Organic amines are predominantly nonfluorescent and are of analytical interest in agricultural and food science, biomedical applications, and biowarfare detection. Alexa Fluor 488 N-hydroxysuccinimidyl ester (AF488 NHS-ester) is an amine-specific fluorescent probe. Here, we demonstrate low limit of detection of long-chain (C9to C18) primary amines and optimize AF488 derivatization of long-chain primary amines. The reaction was found to be equally efficient in all solvents studied (dimethylsulfoxide, ethanol, and N,N-dimethylformamide). While an organic base (N,N-diisopropylethylamine) is required to achieve efficient reaction between AF488 NHS-ester and organic amines with longer hydrophobic chains, high concentrations (>5 mM) result in increased levels of ethylamine and propylamine in the blank. Optimal incubation times were found to be >12 hrs at room temperature. We present an initial capillary electrophoresis separation for analysis using a simple micellar electrokinetic chromatography (MEKC) buffer consisting of 12 mM sodium dodecylsulfate (SDS) and 5 mM carbonate, pH 10. Limits of detection using the optimized labeling conditions and these separation conditions were 5–17 nM. The method presented here represents a novel addition to the arsenal of fluorescent probes available for highly sensitive analysis of small organic molecules.

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Huber, Gerald, e Hubert Schmidbaur. "The Basicity of Silylamines and Alkylamines: An Equilibrium Study of the Competitive Borane Adduct Formation". Zeitschrift für Naturforschung B 53, n.º 10 (1 de outubro de 1998): 1103–8. http://dx.doi.org/10.1515/znb-1998-1005.

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AbstractIn order to investigate the Lewis acid/base chemistry of silylamines in solution, the equilibrium reactions of Me3SiNMe2 / Me3SiNMe2(BH3) and different amines NR3 / amineboranes NR3(BH3) were monitored by 1H NMR spectroscopy in C6D6 and CDCI3 at 60 °C. For the equilibrium of the reference silylamine/-borane and Me3CNMe2 / Me3CNMe2(BH3) values K = 0.35 (AG = 3.1 kJ mol-1) in C6D6 and K = 0.50 (AG = 2.0 kJ mol-1) in CDCl3 have been estimated, showing that both the silylamine and the C/Si-analogous organic amine have very similar donor properties. Small amines like NMe3 proved to be much more powerful donors than the silylamine Me3SiNMe2, whereas bulky amines are less efficient donors, indicating that steric effects play an important role. The formation of BH3 adducts of Me2NSiH3 and (H3Si)3N which could not be followed experimentally owing to the low stability of the products, has been studied by quantum chemical calculations. A comparison with data for Me3N(BH3) shows that the silylamines are poorer donors, but the reason for this remains unclear

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Roman, Gheorghe. "Novel Phenolic 1-aryl-3-arylamino-1-propanones: Synthesis and Characterization". Acta Chemica Iasi 25, n.º 2 (1 de dezembro de 2017): 179–94. http://dx.doi.org/10.1515/achi-2017-0015.

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Abstract A small collection of 1-aryl-3-arylamino-1-propanones having a phenolic moiety in their structure has been obtained by the replacement of the tertiary amino group in ketonic Mannich bases with (hetero)aromatic amines. The installment of the phenolic moiety took place either through the N-alkylation of 4-aminophenol with ketonic Mannich base hydrochlorides, or via amine exchange in ketonic Mannich bases derived from either 2′-hydroxyacetophenone or 4′-hydroxyacetophenone.

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Johnson, B. R., J. H. Peck e R. M. Harris-Warrick. "Distributed amine modulation of graded chemical transmission in the pyloric network of the lobster stomatogastric ganglion". Journal of Neurophysiology 74, n.º 1 (1 de julho de 1995): 437–52. http://dx.doi.org/10.1152/jn.1995.74.1.437.

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1. In the pyloric network of the lobster stomatogastric ganglion, graded synapses organize the network output. The amines dopamine (DA), serotonin, and octopamine each elicit a distinctive motor pattern from a quiescent pyloric network. We have examined the effects of these amines on the graded synaptic strengths between the six major types of neurons of this network to understand how amine modulation of synaptic strength contributes to the amine-induced motor patterns. Here we tested amine affects at 10 different graded chemical synapses of the pyloric network. We show that each amine has a statistically different spectrum of distributed effects across the network synapses. 2. Under our control conditions (isolated pairs of neurons, removal of modulatory input), most of the graded chemical synapses were weak and some synapses were nonfunctional. The output synapses of the ventricular dilator (VD) neuron were significantly stronger than the other synapses. 3. DA altered the synaptic strength of every graded chemical synapse. This amine strengthened the weak chemical output synapses of the anterior burster (AB), lateral pyloric (LP), and pyloric constrictor (PY) neurons and weakened (and in some cases abolished) the strong chemical output synapses of the VD neuron. The AB-->inferior cardiac neuron (IC) and PY-->IC graded chemical synapses were nonfunctional under our control conditions; DA activated these silent synapses. 4. Serotonin enhanced the AB's output chemical synapses but weakened all the other graded chemical synapses examined. Octopamine's effects were much weaker than those of the other two amines. It enhanced the AB-->LP synapse and the LP's output synapses and weakly strengthened the AB-->PY, VD-->LP, and VD-->PY synapses. 5. The amines alter the input resistance of many of the pyloric neurons, and this could contribute to the observed changes in synaptic strength by altering passive current flow between input and output sites in the cells. However, the input resistance changes were relatively small compared with the changes in synaptic strength and cannot alone account for the synaptic modulation. In some cases the sign of the input resistance change was inconsistent with the change in synaptic strength. Thus the amines appear to modify synaptic transmission directly in this system. 6. This study completes our description of amine effects on all the graded synapses of the pyloric network. We summarize our present and earlier work to show that modulators can reconfigure the entire synaptic organization of a neural network by acting at many distributed synaptic sites.(ABSTRACT TRUNCATED AT 400 WORDS)

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Cristiani, Cinzia, Elena Maria Iannicelli-Zubiani, Giovanni Dotelli, Elisabetta Finocchio, Paola Gallo Stampino e Maurizio Licchelli. "Polyamine-Based Organo-Clays for Polluted Water Treatment: Effect of Polyamine Structure and Content". Polymers 11, n.º 5 (16 de maio de 2019): 897. http://dx.doi.org/10.3390/polym11050897.

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Hybrid materials based on clays and polyamines are supposed to be efficient heavy metals sorbents due to the well-known adsorption behaviour of the clay matrix and to the coordination properties of un-protonated amino groups. For this purpose, a montmorillonite clay was modified with three different aliphatic polyamines: L6 and L10 have a linear structure with six and ten amino groups, respectively, while B14 is a branched polyamine with fourteen amino groups. Initial amine concentration was the main parameter investigated and data were fitted with Langmuir and Freundlich models. Interaction mechanisms between clay and amines were deeply investigated by different experimental techniques such as X-ray powder diffraction (XRD), thermal analysis measurements (DTG), Fourier Transform Infrared Spectroscopy (FT-IR) and diffuse reflectance (NIR) spectroscopy. Experimental results showed that the amount of amines efficiently immobilized in the solid phase can be increased by increasing the initial concentration of polyamines in the clay modification process. These data were best fitted by Freundlich model, indicating a presence of surface sites of different nature. In the resulting hybrid materials, neither the accessibility of the NH/NH2 groups of the amines, nor the accessibility of the structural OH of the clay was hindered. Several preliminary tests in La ions’ uptake and release from aqueous solution were also carried out. In the conditions used for this study, total metal ion removal was achieved at sufficiently low linear amine loadings (i.e., 0.45 mmol/gclay for the small L6 amine), suggesting that these hybrid materials are promising for the proposed application in environmental remediation.

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Gough, Alex. "Small animal Review". Companion Animal 27, n.º 9 (2 de julho de 2022): 150. http://dx.doi.org/10.12968/coan.2022.0027.

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Summary: This issue's Small Animal Review features studies that seek to answer the long-standing question of the role of angiotensin-converting enzyme inhibitors in preclinical myxomatous mitral valve disease. Previous recommendations have suggested they are beneficial for use in dogs before they present with clinical signs, if cardiomegaly was present on radiographic or ultrasonographic examination. Systematic reviews and meta-analyses are considered the highest form of evidence and they can be helpful in answering questions when single trials do not have sufficient power to be conclusive.samples in measuring exposure to aromatic amines.

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Maslivetc, Vladimir, Breana Laguera, Sunena Chandra, Ramesh Dasari, Wesley J. Olivier, Jason A. Smith, Alex C. Bissember et al. "Polygodial and Ophiobolin A Analogues for Covalent Crosslinking of Anticancer Targets". International Journal of Molecular Sciences 22, n.º 20 (19 de outubro de 2021): 11256. http://dx.doi.org/10.3390/ijms222011256.

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In a search of small molecules active against apoptosis-resistant cancer cells, including glioma, melanoma, and non-small cell lung cancer, we previously prepared α,β- and γ,δ-unsaturated ester analogues of polygodial and ophiobolin A, compounds capable of pyrrolylation of primary amines and demonstrating double-digit micromolar antiproliferative potencies in cancer cells. In the current work, we synthesized dimeric and trimeric variants of such compounds in an effort to discover compounds that could crosslink biological primary amine containing targets. We showed that such compounds retain the pyrrolylation ability and possess enhanced single-digit micromolar potencies toward apoptosis-resistant cancer cells. Target identification studies of these interesting compounds are underway.

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Hegarty, Eimear, e Francesca Paradisi. "Implementation of Biocatalysis in Continuous Flow for the Synthesis of Small Cyclic Amines". CHIMIA International Journal for Chemistry 74, n.º 11 (25 de novembro de 2020): 890–94. http://dx.doi.org/10.2533/chimia.2020.890.

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Significant progress has been made in establishing transaminases as robust biocatalysts for the green and scalable synthesis of a diverse range of chiral amines. However, very few examples on the amination of small cyclic ketones have been reported. Cyclic ketones are particularly challenging for transaminase enzymes because they do not display the well-defined small and large substituent areas that are characteristic for the bio- catalytic mechanism. In this work, we exploited the broad substrate scope of the (S)-selective transaminase from Halomonas elongata (HeWT) to develop an efficient biocatalytic system in continuous flow to generate a range of small cyclic amines which feature very often in pharmaceuticals and agrochemicals. [3] Tetrahydrofuran-3-one and other challenging prochiral ketones were rapidly (5–45 min) transformed to their corresponding amines with excellent molar conversion (94–99%) and moderate to excellent ee.

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Murphy, S. M., A. Sorooshian, J. H. Kroll, N. L. Ng, P. Chhabra, C. Tong, J. D. Surratt, E. Knipping, R. C. Flagan e J. H. Seinfeld. "Secondary aerosol formation from atmospheric reactions of aliphatic amines". Atmospheric Chemistry and Physics Discussions 7, n.º 1 (10 de janeiro de 2007): 289–349. http://dx.doi.org/10.5194/acpd-7-289-2007.

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Abstract. Although aliphatic amines have been detected in both urban and rural atmospheric aerosols, little is known about the chemistry leading to particle formation or the potential aerosol yields from reactions of gas-phase amines. We present here the first systematic study of aerosol formation from the atmospheric reactions of amines. Based on laboratory chamber experiments and theoretical calculations, we evaluate aerosol formation from reaction of OH, ozone, and nitric acid with trimethylamine, methylamine, triethylamine, diethylamine, ethylamine, and ethanolamine. Entropies of formation for alkylammonium nitrate salts are estimated by molecular dynamics calculations enabling us to estimate equilibrium constants for the reactions of amines with nitric acid. Though subject to significant uncertainty, the calculated dissociation equilibrium constant for diethylammonium nitrate is found to be sufficiently small to allow for its atmospheric formation, even in the presence of ammonia which competes for available nitric acid. Experimental chamber studies indicate that the dissociation equilibrium constant for triethylammonium nitrate is of the same order of magnitude as that for ammonium nitrate. All amines studied form aerosol when photooxidized in the presence of NOx with the majority of the aerosol mass present at the peak of aerosol growth consisting of aminium (R3NH+) nitrate salts, which repartition back to the gas phase as the parent amine is consumed. Only the two tertiary amines studied, trimethylamine and triethylamine, are found to form significant non-salt organic aerosol when oxidized by OH or ozone; calculated organic mass yields for the experiments conducted are similar for ozonolysis (15% and 5% respectively) and photooxidation (23% and 8% respectively). The non-salt organic aerosol formed appears to be more stable than the nitrate salts and does not quickly repartition back to the gas phase.

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Murphy, S. M., A. Sorooshian, J. H. Kroll, N. L. Ng, P. Chhabra, C. Tong, J. D. Surratt, E. Knipping, R. C. Flagan e J. H. Seinfeld. "Secondary aerosol formation from atmospheric reactions of aliphatic amines". Atmospheric Chemistry and Physics 7, n.º 9 (8 de maio de 2007): 2313–37. http://dx.doi.org/10.5194/acp-7-2313-2007.

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Abstract. Although aliphatic amines have been detected in both urban and rural atmospheric aerosols, little is known about the chemistry leading to particle formation or the potential aerosol yields from reactions of gas-phase amines. We present here the first systematic study of aerosol formation from the atmospheric reactions of amines. Based on laboratory chamber experiments and theoretical calculations, we evaluate aerosol formation from reaction of OH, ozone, and nitric acid with trimethylamine, methylamine, triethylamine, diethylamine, ethylamine, and ethanolamine. Entropies of formation for alkylammonium nitrate salts are estimated by molecular dynamics calculations enabling us to estimate equilibrium constants for the reactions of amines with nitric acid. Though subject to significant uncertainty, the calculated dissociation equilibrium constant for diethylammonium nitrate is found to be sufficiently small to allow for its atmospheric formation, even in the presence of ammonia which competes for available nitric acid. Experimental chamber studies indicate that the dissociation equilibrium constant for triethylammonium nitrate is of the same order of magnitude as that for ammonium nitrate. All amines studied form aerosol when photooxidized in the presence of NOx with the majority of the aerosol mass present at the peak of aerosol growth consisting of aminium (R3NH+) nitrate salts, which repartition back to the gas phase as the parent amine is consumed. Only the two tertiary amines studied, trimethylamine and triethylamine, are found to form significant non-salt organic aerosol when oxidized by OH or ozone; calculated organic mass yields for the experiments conducted are similar for ozonolysis (15% and 5% respectively) and photooxidation (23% and 8% respectively). The non-salt organic aerosol formed appears to be more stable than the nitrate salts and does not quickly repartition back to the gas phase.

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Sintermann, J., e A. Neftel. "Ideas and perspectives: on the emission of amines from terrestrial vegetation in the context of new atmospheric particle formation". Biogeosciences 12, n.º 11 (3 de junho de 2015): 3225–40. http://dx.doi.org/10.5194/bg-12-3225-2015.

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Abstract. In this article we summarise recent science which shows how airborne amines, specifically methylamines (MAs), play a key role in new atmospheric particle formation (NPF) by stabilising small molecule clusters. Agricultural emissions are assumed to constitute the most important MA source, but given the short atmospheric residence time of MAs, they can hardly have a direct impact on NPF events observed in remote regions. This leads us to the presentation of existing knowledge focussing on natural vegetation-related MA sources. High MA contents as well as emissions by plants was already described in the 19th century. Strong MA emissions predominantly occur during flowering as part of a pollination strategy. The behaviour is species-specific, but examples of such species are common and widespread. In addition, vegetative plant tissue exhibiting high amounts of MAs might potentially lead to significant emissions. The decomposition of organic material constitutes another, potentially ubiquitous, source of airborne MAs. These mechanisms would provide sources, which could be crucial for the amine's role in NPF, especially in remote regions. Knowledge about vegetation-related amine emissions is, however, very limited, and thus it is also an open question how global change and the intensified cycling of reactive nitrogen over the last 200 years have altered amine emissions from vegetation with a corresponding effect on NPF.

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Sintermann, J., e A. Neftel. "Ideas and Perspectives: On the emission of amines from terrestrial vegetation in the context of atmospheric new particle formation". Biogeosciences Discussions 12, n.º 4 (16 de fevereiro de 2015): 3211–43. http://dx.doi.org/10.5194/bgd-12-3211-2015.

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Abstract. In this article we summarise recent science, which shows how airborne amines, specifically methylamines (MAs), play a key role in atmospheric new particle formation (NPF) by stabilising small molecule clusters. Agricultural emissions are assumed to constitute the most important MA source, but given the short atmospheric residence time of MAs, they can hardly have a direct impact on NFP events observed in remote regions. This leads us to the presentation of existing knowledge focussing on natural vegetation-related MA sources. High MA contents as well as emissions by plants have already been described in the 19th century. Strong MA emissions predominantly occur during flowering as part of a pollination strategy. The behaviour is species specific, but examples of such species are common and widespread. In addition, vegetative plant tissue exhibiting high amounts of MAs might potentially lead to significant emissions, and the decomposition of organic material could constitute another source for airborne MAs. These mechanisms would provide sources, which could be crucial for the amine's role in NPF, especially in remote regions. Knowledge about vegetation-related amine emissions is, however, very limited and thus it is also an open question how Global Change and the intensified cycling of reactive nitrogen over the last 200 years have altered amine emissions from vegetation with a corresponding effect on NPF.

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Flores, Rafael, Shoaib Iqbal e Donald Sikazwe. "Phenylacetyl-/Trolox- Amides: Synthesis, Sigma-1, HDAC-6, and Antioxidant Activities". International Journal of Molecular Sciences 24, n.º 20 (18 de outubro de 2023): 15295. http://dx.doi.org/10.3390/ijms242015295.

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In search of novel multi-mechanistic approaches for treating Alzheimer’s disease (AD), we have embarked on synthesizing single small molecules for probing contributory roles of the following combined disease targets: sigma-1 (σ-1), class IIb histone deacetylase-6 (HDAC-6), and oxidative stress (OS). Herein, we report the synthesis and partial evaluation of 20 amides (i.e., phenylacetic and Trolox or 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid derivatives). Target compounds were conveniently synthesized via amidation by either directly reacting acyl chlorides with amines or condensing acids with amines in the presence of coupling agents 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo [4,5-b] pyridinium 3-oxide hexafluorophosphate (HATU) or 1,1′-carbonyldiimidazole (CDI). Overall, this project afforded compound 8 as a promising lead with σ-1 affinity (Ki = 2.1 μM), HDAC-6 (IC50 = 17 nM), and antioxidant (1.92 Trolox antioxidant equivalents or TEs) activities for optimization in ensuing structure–activity relationship (SAR) studies.

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Reiner, Eric J., Raymond A. Poirier, Michael R. Peterson, Imre G. Csizmadia e Alex G. Harrison. "Unimolecular fragmentation of some gaseous protonated amines". Canadian Journal of Chemistry 64, n.º 8 (1 de agosto de 1986): 1652–60. http://dx.doi.org/10.1139/v86-272.

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The proton-transfer chemical ionization mass spectra of the C3 to C5 monoalkyl amines as well as a number of di- and tri-alkyl amines have been determined using H3+ and (in some cases) HCO+ as protonating agent. The RNH3+ ions fragment to form alkyl ions R+ and eliminate alkenes to form NH4+. In addition, abundant immonium ions are observed in the CI mass spectra corresponding to elimination of alkane from RNH3+ or to direct alkide ion abstraction from RNH2; these ions serve to characterize the alkyl groups attached to the α-carbon atom of the amine. Although alkane elimination from RNH3+ is the thermochemically favoured reaction, only R+ and NH4+ are formed in decomposition of metastable RNH3+ ions. The potential energy profile for fragmentation of i-C3H7NH3+ has been calculated by abinitio molecular orbital methods. These calculations show that CH4 elimination has a large energy barrier additional to the reaction endothermicity while formation of NH4+ has only a small additional barrier and formation of C3H7+ has no barrier additional to the endothermicity. It is concluded that the immonium ions probably arise primarily by direct alkide ion abstraction reactions.

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Malloy, Q. G. J., B. Warren, D. R. Cocker, M. E. Erupe e P. J. Silva. "Secondary organic aerosol formation from primary aliphatic amines with NO<sub>3</sub> radical". Atmospheric Chemistry and Physics Discussions 8, n.º 4 (4 de julho de 2008): 12695–720. http://dx.doi.org/10.5194/acpd-8-12695-2008.

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Abstract. Primary aliphatic amines are an important class of nitrogen containing compounds found to be emitted from automobiles, waste treatment facilities and agricultural animal operations. A series of experiments conducted at the UC-Riverside/CE-CERT Environmental Chamber is presented in which oxidation of methylamine, ethylamine, propylamine, and butylamine with NO3 has been investigated. Very little aerosol formation is observed in the presence of O3 only. However, after addition of NO, and by extension NO3, large yields of aerosol mass loadings (~44% for butylamine) are seen. Aerosol generated was determined to be organic in nature due to the small fraction of NO and NO2 in the total signal (<17% for all amines tested) as detected by an aerosol mass spectrometer (AMS). We propose a reaction mechanism between carbonyl containing species and the parent amine leading to formation of particulate imine products. These findings can have significant impacts on rural communities and lead to elevated nighttime PM loadings, when significant levels on NO3 exist.

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Malloy, Q. G. J., B. Warren, D. R. Cocker III, M. E. Erupe e P. J. Silva. "Secondary organic aerosol formation from primary aliphatic amines with NO<sub>3</sub> radical". Atmospheric Chemistry and Physics 9, n.º 6 (23 de março de 2009): 2051–60. http://dx.doi.org/10.5194/acp-9-2051-2009.

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Abstract. Primary aliphatic amines are an important class of nitrogen containing compounds emitted from automobiles, waste treatment facilities and agricultural animal operations. A series of experiments conducted at the UC-Riverside/CE-CERT Environmental Chamber is presented in which oxidation of methylamine, ethylamine, propylamine, and butylamine with O3 and NO3 have been investigated. Very little aerosol formation is observed in the presence of O3 only. However, after addition of NO, and by extension NO3, large aerosol mass yields (~44% for butylamine) are seen. Aerosol generated was determined to be organic in nature due to the small fraction of NO and NO2 in the total signal (<1% for all amines tested) as detected by an aerosol mass spectrometer (AMS). We propose a reaction mechanism between carbonyl containing species and the parent amine leading to formation of particulate imine products. These findings can have significant impacts on rural communities with elevated nighttime PM loadings, when significant levels of NO3 exist.

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35

Håland, Alexander, Tomáš Mikoviny, Elisabeth Emilie Syse e Armin Wisthaler. "On the development of a new prototype PTR-ToF-MS instrument and its application to the detection of atmospheric amines". Atmospheric Measurement Techniques 15, n.º 21 (2 de novembro de 2022): 6297–307. http://dx.doi.org/10.5194/amt-15-6297-2022.

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Abstract. We herein report on the development of a new prototype PTR-ToF-MS (proton-transfer-reaction time-of-flight mass spectrometry) instrument that combines a hollow cathode glow discharge (HCGD) ion source with a focusing ion–molecule reactor (FIMR), which consists of a resistive glass drift tube surrounded by quadrupole rods. The new instrument configuration hybridizes the two main current commercial PTR-ToF-MS instrument designs. We provide a detailed technical description of the new analyzer and its optimized operational settings for detecting volatile amines via proton transfer reactions from hydronium (H3O+) or ammonium (NH4+) ions. We show that the new prototype PTR-ToF-MS instrument is capable of monitoring rapid changes of sticky amines on the timescale of a few seconds and detects atmospheric variations of amines down to single-digit parts per trillion by volume (pptv) levels. Application examples given include the real-time monitoring of (i) methylamine emitted from a Chenopodium vulvaria L. plant, (ii) small alkylamines in ambient air on site of an agricultural research center (Senter for husdyrforsøk, Ås, Norway), and (iii) an industrial amine (2-amino-2-methylpropan-1-ol, AMP) on site and downwind of a carbon dioxide (CO2) capture test center (Technology Centre Mongstad – TCM, Mongstad, Norway).

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Liu, Huaizhu. "Preparation and performance evaluation of small molecule ammonium salt inhibitors synthesized from mixed amines". Highlights in Science, Engineering and Technology 2 (22 de junho de 2022): 112–19. http://dx.doi.org/10.54097/hset.v2i.562.

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This paper focuses on the synthesis of polyhydroxy small molecule amines using mixed amines as raw materials. The anti-swelling experiment, swelling shrinkage experiment, linear swelling rate and clay hydration experiments were used to evaluate the application effect of the synthesized products in oilfield water-based drilling fluids. and suitable inhibitors were selected. The inhibition mechanism was investigated by TGA, laser particle size analysis and SEM. The inhibition of clay hydration swelling was best at a concentration of 0.1% with a 1:3 mass ratio of mixed amines to phosphoric acid, i.e., the product HS-1. The results of anti-swelling, swelling shrinkage and linear expansion experiments showed that the anti-swelling rate of 0.1% HS-1 on clay was 72.97%, the swelling shrinkage rate was 54.50% and the linear expansion rate was 27.30%, which was similar to the effectiveness of 4.0% KCl. It showed good inhibition of hydration swelling dispersion of clay.

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Troiano, Jennifer L., Gongfang Hu, Robert H. Crabtree e Gary W. Brudvig. "Diazo coupling for surface attachment of small molecules to TiO2 nanoparticles". Chemical Communications 56, n.º 65 (2020): 9340–43. http://dx.doi.org/10.1039/d0cc03631e.

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Bzdek, B. R., D. P. Ridge e M. V. Johnston. "Amine exchange into ammonium bisulfate and ammonium nitrate nuclei". Atmospheric Chemistry and Physics Discussions 10, n.º 1 (5 de janeiro de 2010): 45–68. http://dx.doi.org/10.5194/acpd-10-45-2010.

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Abstract. The exchange kinetics and thermodynamics of amines for ammonia in small (1–2 nm diameter) ammonium bisulfate and ammonium nitrate clusters were investigated using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Ammonium salt clusters were reacted with amine gas at constant pressure to determine the kinetics of exchange. The reverse reactions, where aminium salt clusters reacted with ammonia gas, were also studied, and no substitution of ammonia for amine was observed. Gibbs free energy changes for these substitutions were determined to be highly exothermic, −7 kJ/mol or more negative in all cases. Uptake coefficients (reaction probabilities) were found to be near unity, implying that complete exchange of ammonia in small salt clusters by amine would be expected to occur within several seconds to minutes in the ambient atmosphere. These results suggest that if salt clusters are a component of the sub-3 nm cluster pool, they are likely to be aminium salts rather than ammonium salts, even if they were initially formed as ammonium salts.

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39

Bzdek, B. R., D. P. Ridge e M. V. Johnston. "Amine exchange into ammonium bisulfate and ammonium nitrate nuclei". Atmospheric Chemistry and Physics 10, n.º 8 (16 de abril de 2010): 3495–503. http://dx.doi.org/10.5194/acp-10-3495-2010.

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Abstract. The exchange kinetics and thermodynamics of amines for ammonia in small (1–2 nm diameter) ammonium bisulfate and ammonium nitrate clusters were investigated using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Ammonium salt clusters were reacted with amine gas at constant pressure to determine the kinetics of exchange. The reverse reactions, where aminium salt clusters reacted with ammonia gas, were also studied, and no substitution of ammonia for amine was observed. Gibbs free energy changes for these substitutions were determined to be highly exothermic, −7 kJ/mol or more negative in all cases. Uptake coefficients (reaction probabilities) were found to be near unity, implying that complete exchange of ammonia in small clusters by amine would be expected to occur within several seconds to minutes in the ambient atmosphere. These results suggest that if salt clusters are a component of the sub-3 nm cluster pool, they are likely to be aminium salts rather than ammonium salts, even if they were initially formed as ammonium salts.

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Rollmann, L. Deane, John L. Schlenker, Stephen L. Lawton, Carrie L. Kennedy, Gordon J. Kennedy e Douglas J. Doren. "On the Role of Small Amines in Zeolite Synthesis". Journal of Physical Chemistry B 103, n.º 34 (agosto de 1999): 7175–83. http://dx.doi.org/10.1021/jp991913m.

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Behjatmanesh-Ardakani, R., M. A. Karimi e A. Ebady. "Cavity shape effect on pKa prediction of small amines". Journal of Molecular Structure: THEOCHEM 910, n.º 1-3 (setembro de 2009): 99–103. http://dx.doi.org/10.1016/j.theochem.2009.06.019.

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Lowis, Susan, M. A. Eastwood e W. G. Brydon. "The influence of creatinine, lecithin and choline feeding on aliphatic amine production and excretion in the rat". British Journal of Nutrition 54, n.º 1 (julho de 1985): 43–51. http://dx.doi.org/10.1079/bjn19850091.

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1. The excretion of aliphatic amines, methylamine, dimethylamine and trimethylamine in the urine and faeces of rats fed on a control diet and diets supplemented with creatinine, lecithin or choline were measured over a 14 d feeding period.2. The rats were then killed and concentrations of amines in small and large intestinal contents measured.3. Adding creatinine to the diet resulted in a significant increase of methylamine excretion in the faeces and urine. The amount of methylamine found in all parts of the intestine increased, especially in the caecum.4. Adding lecithin to the diet resulted in an increase in the methylamine excretion only, and no change in the concentrations of amines found in the intestine, except for trimethylamine which was significantly increased in the caecum and colon.5. Adding choline to the diet resulted in a significant increase in excretion of trimethylamine and, to a lesser extent, methylamine. The levels of amines found in the gut increased, dimethylamine being increased in the small bowel, and methylamine and trimethylamine in the caecum.

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Wang, Xuelei, Zhaojun Dong, Chao Meng, Wei Wang, Hairui Yang, Xizhun Zhuo e Shaobin Yang. "The Different Effects of Organic Amines on Synthetic Metal Phosphites/Phosphates". Materials 13, n.º 7 (9 de abril de 2020): 1752. http://dx.doi.org/10.3390/ma13071752.

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Four metal phosphites/phosphates crystal materials C8N4H34Al2P4O18 (1), C3N2H17GaP2O8 (2), H5In2P3O10 (3), and H9In2P3O13 (4) have been solvothermally synthesized by organic amines in the presence of mixed solvents. Structural analyses indicate that compound 1 and 2 show one-dimensional (1D) chain structures; compound 3 and 4 are three-dimensional (3D) inorganic open-framework indium phosphites. Organic amines show different mechanisms in the four compounds. The 2,2′-bipyridine organic amine acts as a template source and it breaks down small molecules, which enter into the structure of compound 1. For compound 2, 1,2-propanediamine has a role as protonated template and it forms a hydrogen bond with the inorganic skeleton structure. As for compound 3 and 4 without the organic template, the benzylamine and 2,2′-bipyridine mainly serve as structure-directing agent. Especially, compound 3 has an odd seven-ring channel, and compound 4 contains 3D intersecting six-ring, eight-ring, and 10-ring channels. X-ray diffraction (XRD), scanning electron microscopy (SEM), CHN, inductive coupled plasma (ICP), Infrared (IR), and thermal gravimetric (TG) analyze the four compounds.

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Tilbrook, Matthew G., Robert V. Stick e Spencer J. Williams. "β-Acarbose. VIII.The Synthesis of Some N-Linked Carba-Oligosaccharides". Australian Journal of Chemistry 52, n.º 9 (1999): 895. http://dx.doi.org/10.1071/ch99031.

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Two carbohydrate triflates have been used to alkylate a 1-epivalienamine derivative to give small amounts of the desired secondary amines, in addition to amounts of the products of elimination. Deprotection of the secondary amines afforded a carba-disaccharide and a carba-tetrasaccharide which have been shown to be good inhibitors of β-glucosidases.

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Donnelly, Zhang e Baumann. "Development of a Telescoped Flow Process for the Safe and Effective Generation of Propargylic Amines". Molecules 24, n.º 20 (10 de outubro de 2019): 3658. http://dx.doi.org/10.3390/molecules24203658.

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Propargylic amines are important multifunctional building blocks that are frequently exploited in the synthesis of privileged heterocyclic entities. Herein we report on a novel flow process that achieves the safe and effective on-demand synthesis of propargylic amines in a telescoped manner. This process minimizes exposure to hazardous azide intermediates and renders a streamlined route into these building blocks. The value of this approach is demonstrated by the rapid generation of a small selection of drug-like thiazolines that result from a high-yielding reaction cascade between propargylic amines with different aryl isothiocyanates.

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Bisdas, Sotirios, Stefano Casagranda, Diana Roettger, Sebastian Brandner, Lewis Thorne e Laura Mancini. "Amide proton transfer MRI can accurately stratify gliomas according to their IDH mutation and 1p/19q co-deletion status." Journal of Clinical Oncology 38, n.º 15_suppl (20 de maio de 2020): 2561. http://dx.doi.org/10.1200/jco.2020.38.15_suppl.2561.

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2561 Background: Amide proton transfer (APT) MRI provides sensitive metrics at the amides and amines offsets from the water resonance and has been shown in small cohorts to differentiate low from high grade gliomas with better diagnostic performance than diffusion- and perfusion-weighted MRI. The purpose of our study was to assess APT-MRI performance to stratify gliomas according to their IDH mutation and 1p/19q status. Methods: Forty-five patients with primary gliomas and diffuse astrocytomas (26 WHO grade II, 11 WHO grade III, 8 WHO grade IV) underwent prospectively multi-parametric MRI with APT imaging at 3T scanner. The molecular classification identified 9 patients with IDH-wildtype, 1p/19q retained and 36 with IDH-mutant (22 had 1p/19q-retained, 14 had 1p/19q-codeleted). Tumour segmentations were manually created and the masks were superimposed on the calculated magnetisation transfer ratio asymmetry (MTRasym) spectra and proton transfer ratio APT maps. Individual and group analysis was conducted to analyse the statistical differences between quantitative imaging parameters for the IDH mutation and 1p/19q codeletion statuses. Results: The MTRasym spectra showed a clear difference between IDH-wildtype and IDH-mutant gliomas, with the IDH-mutant gliomas presenting a stronger contribution in the amines (p < 0.001). In IDH-mutant 1p/19q-retained and IDH-mutant 1p/19q-codeleted, the MTRasym spectra showed similarities in shape with higher intensity (approx. 60%) for the IDH-mutant 1p/19q-retained gliomas over the entire spectrum indicating an increased content in amines and amides in IDH-mutant 1p/19q-retained (p < 0.01). Notably, the latter entities showed higher amides levels than the IDH-wildtype gliomas (p < 0.03). Conclusions: APT-MRI shows a remarkable potential to disentangle the protein metabolism in gliomas, to link metabolic patterns to the IDH and 1p/19q status and hence provide robust surrogate biomarkers for non-invasive histomolecular classification with potential use as treatment monitoring tools.

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Pospelov, Evgeny V., e Alexey Yu Sukhorukov. "Building Up a Piperazine Ring from a Primary Amino Group via Catalytic Reductive Cyclization of Dioximes". International Journal of Molecular Sciences 24, n.º 14 (22 de julho de 2023): 11794. http://dx.doi.org/10.3390/ijms241411794.

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Piperazine is one of the most frequently found scaffolds in small-molecule FDA-approved drugs. In this study, a general approach to the synthesis of piperazines bearing substituents at carbon and nitrogen atoms utilizing primary amines and nitrosoalkenes as synthons was developed. The method relies on sequential double Michael addition of nitrosoalkenes to amines to give bis(oximinoalkyl)amines, followed by stereoselective catalytic reductive cyclization of the oxime groups. The method that we developed allows a straightforward structural modification of bioactive molecules (e.g., α-amino acids) by the conversion of a primary amino group into a piperazine ring.

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Galman, James L., Iustina Slabu, Nicholas J. Weise, Cesar Iglesias, Fabio Parmeggiani, Richard C. Lloyd e Nicholas J. Turner. "Biocatalytic transamination with near-stoichiometric inexpensive amine donors mediated by bifunctional mono- and di-amine transaminases". Green Chemistry 19, n.º 2 (2017): 361–66. http://dx.doi.org/10.1039/c6gc02102f.

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Zainal Abidin, Ma Umaira Suhaddha, Hilmi Mukhtar e Maizatul Shima Shaharun. "Removal of Amines from Wastewater Using Membrane Separation Processes". Applied Mechanics and Materials 625 (setembro de 2014): 639–43. http://dx.doi.org/10.4028/www.scientific.net/amm.625.639.

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Natural gas is one of the energy sources in the world. It consists of predominantly methane (CH4), ethane (C2H6), ethylene (C2H4), propane (C3H8) butane (C4H10), pentane (C5H12) and some impurities particularly hydrogen sulfide (H2S) and carbon dioxide (CO2) that need to be treated prior utilized. Amine solution such as diisopropanolamine (DIPA) is used to remove the CO2 and H2S in natural gas processing. However a small amount of amines losses in some unit operations causing amines discharged into the effluent wastewater. The objective of this study are to investigate the flux of water and permeate, and rejection of DIPA solution across reverse osmosis, nanofiltration and ultrafiltration membrane which known as AFC99, AFC40 and CA202 respectively. This paper studies the effect of cross-flow velocity on permeate flux and the effect of feed concentration on observed rejection of DIPA solution across AFC99, AFC40 and CA202 over the operating pressure. The results showed a significant role of cross-flow velocity on membrane performance from aspect flux obtained and phenomenon of concentration polarization that would increase the transport resistance of permeate flow. The highest flux can be achieved by high cross-flow velocity. While for rejection study, rejection of all membranes increase with increase of pressure yet decrease with concentration.

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Zhang, Qin, Qiuyun Mao, Cong Shang, Ya-Nan Chen, Xin Peng, Hongwei Tan e Huiliang Wang. "Simple aliphatic oximes as nonconventional luminogens with aggregation-induced emission characteristics". Journal of Materials Chemistry C 5, n.º 15 (2017): 3699–705. http://dx.doi.org/10.1039/c7tc00783c.

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