197,686 research outputs found
Tribological performance of low viscosity halogen-free ammonium based protic ionic liquids with carboxylate anions as neat lubricants
No full textThe tribological performance of six low viscosity, hydrophobic, halogen- sulfur-, and phosphorous free trioctylammonium-based protic ionic liquids with 2-naphthoate, 4-tert-butylbenzoate, 2-hexyldecanoate, 4-phenylbutanoate, 3,4-dimethylbenzoate, and salicylate anions were studied as lubricants for steel-steel interfaces using a four-ball tribo-tester. The results showed a significant friction reduction up-to 28 ̶ 65% compared to polyalphaolefin lube base oil. Where the salicylate protic ionic liquid showed the lowest coefficient of friction. In terms of wear, the 2-naphthoate and salicylate protic ionic liquids exhibited wear scar diameter values lower than polyalphaolefin by 4.7% and 0.42%, respectively. The scanning electron microscopy and X-ray photoelectron spectrometer analysis outcomes of the wear scar surfaces indicated that tribo-chemical reactions were involved among the protic ionic liquid molecules and the steel surfaces during the tribo-test, developing a protective boundary film, which contributed significantly to the lubrication performance of the protic ionic liquids’ lubricants. No corrosion was observed for the copper strip corrosion test carried out to examine the corrosion characteristics of the studied protic ionic liquids. The overall results confirm the high capability of applying this group of protic ionic liquids as lubricants
Ultrastable Superbase-Derived Protic Ionic Liquids
No full textProtic ionic liquids are synthesized via proton transfer from acids to organic bases. One of the key issues associated with conventional protic ionic liquids is the thermal instability resulting from temperature-induced decomposition via reverse proton transfer. This shortcoming significantly hampers the use of these protic ionic liquids in separations, electrochemical capacitors, fuel cells, and so forth. Herein we show that it is possible to prepare protic ionic liquids with thermal stabilities approaching those of common aprotic ionic liquids. Our new class of protic ionic liquids, derived via integrated neutralization and metathesis of superbasic phosphazenes or guanidines, exhibits exceptionally low vapor pressures at 150 °C while being stable to strong alkali agents such as aqueous KOH, suggesting potential in energy-related applications, including electrochemical capacitors and PEM-type fuel cells
Clinical features of infection caused by non-tuberculous mycobacteria: 7 years' experience
No full textIntroduction Non-tuberculous mycobacteria (NTM) are ubiquitous organisms associated with various infections. The aim of the study was to determine the most relevant clinical characteristics of NTM during the 7-year period.Methodology A retrospective study of NTM infections was conducted between January 2009 and December 2016. The American Thoracic Society/Infectious Disease Society of America criteria were used to define cases of pulmonary or an extrapulmonary site.Results A total of 85 patients were included in the study. Pulmonary cases predominated 83/85 (98%), while extrapulmonary NTM were present in 2/95 (2%) patients. Overall, ten different NTM species were isolated. The most common organisms were slow-growing mycobacteria (SGM) presented in 70/85 (82.35%) patients. Isolated SGM strains were Mycobacterium avium complex (MAC) in 25/85 (29.41%) patients, M. xenopi in 20/85 (23.53%) patients, M. kansasii in 15/85 (17.65%) patients and M. peregrinum and M. gordonae in 5/85 (5.88%) patients each. Isolated rapid-growing mycobacteria (RGM) strains were M. abscessus in 8/85 (9.41%) patients, M. fortuitum in 4/85 (4.71%) patients and M. chelonae in 3/85 (3.53%) patients. Almost all patients (98%; 83/85) had comorbidities. Among 75 (88.24%) patients who completed follow-up, 59 (69.41%), 10 (11.76%) and 6 (7%), were cured, experienced relapse and died, respectively.Conclusion In the present study, pulmonary NTM infections were more frequent compared to extrapulmonary disease forms. SGM were most common isolates with MAC pulmonary disease the most frequently found. Comorbidities have an important role in NTM occurrence. Further investigation should focus on an NTM drug susceptibility testin
Synthesis and Helix Formation of Poly(<i>m</i>-phenylene)s Bearing Optically Active Oligo(ethylene oxide) Side Chains in Protic Media
No full textSynthesis and Helix Formation of Poly(m-phenylene)s Bearing Optically Active Oligo(ethylene oxide) Side Chains in Protic Medi
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
Hydrophilic sensor membrane based on cation-selective protic chromoionophore
No full textThe first potassium optode based on a protic chromoionophore immobilized in a hydrogel matrix is presented. The highly selective protic chromoionophore consists of a cryptohemispherand moiety and a trinitroanilino chromophore part. The acidifying power of potassium ions over sodium ions is 0.6 pH units. This correlates with the findings in solution. In contrast to several crown and ate-crown based chromophores the highly preorganized moiety allows ion detection even in aqueous environment. The detection limit for potassium ions at pH 7.7 is 5 mu M
A Structural Theorems for (m; n)-quasi-ideal Semigroups
No full textThe definition of (m; n)-ideal and (m; n)-quasi-ideal on emigroup is given in [3]. They have been studied in many papers, recently in papers [4], [5] and [6]. In this paper we introduce the notion of (m; n)-quasi-ideal semigroup and consider some general properties of this class of semigroups.Also, we introduce the notion of an (m; n)-duo quasi-ideal semigroup and give their a structural description
Solvate and protic ionic liquids from aza-crown ethers: synthesis, thermal properties, and LCST behavior
No full textIn recent years, solvate and protic ionic liquids (ILs) have attracted much attention. We synthesized both types of ILs from alkyl aza-crown ethers (L = N-propyl-1-aza-15-crown-5 (L1) and N-C6F13C2H4-1-aza-15-crown-5 (L2)). The solvate ILs [ML][Tf2N] (M = Na+, K+) were solids (Tm = 58-68 °C), whereas the solvate ILs [ML][Tf2N] (M = Li+, Ag+) and protic ILs [HL][Tf2N] were liquids with low glass transition temperatures. The ILs containing Na ions were more crystalline and exhibited higher melting points than the other ILs. The decomposition temperatures of the protic ILs were higher than those of the solvate ILs. A protic IL with a paramagnetic anion, [HL1][FeCl4] (Tm = 70.5 °C), was also synthesized and its crystal structure was determined. The solvate ILs [NaL2][X] (X = Cl−, CF3CO2−, TsO−, PhSO3−) exhibited a lower critical solution temperature (LCST)-type behavior in water. The effects of salt addition on the LCST of L2 were also investigated. The LCST of these ILs generally increased with increasing hydrophilicity or basicity of the counter anion. This tendency, which is nearly opposite to that of ILs with quaternary onium cations, is ascribed to the amphiphilic nature of the cation. The corresponding protic ILs did not exhibit LCST behavior
Surfactant Self-Assembly Nanostructures in Protic Ionic Liquids
No full textThe existence and properties of mesoscopic self-assembly structures formed by surfactants in protic ionic liquid solutions are reported. Micellar aggregates of n-alkyltrimethylammonium (n = 10, 12, 14, 16) chlorides and bromides and of n-alkylpyridinium (n = 12, 16) chlorides in ethylammonium nitrate and propylammonium nitrate were observed by means of several experimental techniques, including surface tension, transmission electron micrography, dynamic light scattering, and potentiometry using surfactant-selective electrodes. The effect of the alkyl chain length of both solute and solvent molecules on the critical micelle concentration is discussed, and a Stauff-Klevens law is seen to apply to surfactant solutions in both protic ionic liquids. The counterion role is also a matter of study in the case of alkyltrimethylammonium-based surfactants, and the presently reported evidence suggests that the place of the surfactant counterion in the Hoffmeister's series could determine its effect on micellization in IL solution. The size distribution of the aggregates is also analyzed together with the Gibbs free energies of micellization and the minimum surface area per monomer in all of the studied cases. All of the hereby reported evidence suggests that the negative entropic contribution arising from the release of the solvent layer upon micellization is also the driving force of conventional surfactant self-association in protic ionic liquids. © 2011 American Chemical Society
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
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