Status of a Comprehensive Validation of the Navy's F/A-18A/B/C/D Aerodynamics Model.

Bonner, Michael S.; Gingras, David R.

doi:10.21236/ada309807

Cited by 4 publications

(5 citation statements)

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“…The red-shift in water compared with air can be explained by the hydrogen bonding of water molecules to the organic molecule. The amide I band will also red-shift relative to air when bonded to the NH of urea, the NH of another amide, , or through contact pairing with a metal ion. , However, these latter red shifts are almost always smaller than the one for water, which involves significant charge transfer to the σ* orbital of water’s OH bond . As a consequence, the amide I band appears to blue-shift in bulk aqueous solution upon interaction with most species other than water.…”

Section: Resultsmentioning

confidence: 99%

“…However, it has been a particular challenge to obtain quantitative binding constant information for metal cations with amide moieties. There are a few structural studies in the literature focusing on amide–cation interactions in nonaqueous media , and in the solid phase . Five decades ago, Bello and co-workers reported qualitative association of Li + and Ca 2+ with the simple amide-containing compounds, N -methyl acetamide (NMA) and N , N dimethyl acetamide, at very high concentrations of the organic molecule in aqueous solutions by viscosity and calorimetric methods. − In the solid state, these same authors found adducts between cations and amide-containing molecules by X-ray crystallography.…”

Section: Introductionmentioning

confidence: 99%

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Cations Bind Only Weakly to Amides in Aqueous Solutions

2013

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We investigated salt interactions with butyramide as a simple mimic of cation interactions with protein backbones. The experiments were performed in aqueous metal chloride solutions using two spectroscopic techniques. In the first, which provided information about contact pair formation, the response of the amide I band to the nature and concentration of salt was monitored in bulk aqueous solutions via attenuated total reflection Fourier transform infrared spectroscopy. It was found that molar concentrations of well-hydrated metal cations (Ca(2+), Mg(2+), Li(+)) led to the rise of a peak assigned to metal cation-bound amides (1645 cm(-1)) and a decrease in the peak associated with purely water-bound amides (1620 cm(-1)). In a complementary set of experiments, the effect of cation identity and concentration was investigated at the air/butyramide/water interface via vibrational sum frequency spectroscopy. In these studies, metal ion-amide binding led to the ordering of the adjacent water layer. Such experiments were sensitive to the interfacial partitioning of cations in either a contact pair with the amide or as a solvent separated pair. In both experiments, the ordering of the interactions of the cations was: Ca(2+) > Mg(2+) > Li(+) > Na(+) ≈ K(+). This is a direct cationic Hofmeister series. Even for Ca(2+), however, the apparent equilibrium dissociation constant of the cation with the amide carbonyl oxygen was no tighter than ∼8.5 M. For Na(+) and K(+), no evidence was found for any binding. As such, the interactions of metal cations with amides are far weaker than the analogous binding of weakly hydrated anions.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Cations Bind Only Weakly to Amides in Aqueous Solutions

2013

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“…This was unexpected but may be the case because the strength of the hydrogen-bonding network is reflected in the relatively high boiling point of NMF liquid (180−185 °C). The effect on the ν s (CO) band of adding cations to pure liquid NMF has received little attention, but Bonner and Jordan studied this using both infrared and Raman spectroscopy and found that the addition of some salts caused the band to shift to higher wavenumbers. Some examples are NaI (1671 cm -1 ), LiI (1667 cm -1 ), LiCl (1667 cm -1 ), and NaPF 6 (1675 cm -1 ).…”

Section: Resultsmentioning

confidence: 99%

“…Some examples are NaI (1671 cm -1 ), LiI (1667 cm -1 ), LiCl (1667 cm -1 ), and NaPF 6 (1675 cm -1 ). This increase was attributed to the disruption of the strong hydrogen-bonding network between the NMF molecules, but herein the effect of the large planar clay anion may also exert an influence on the ν s (CO) …”

Section: Resultsmentioning

confidence: 99%

Thermal and Spectroscopic Characterization of N-Methylformamide/Ca-, Mg-, and Na-Exchanged Montmorillonite Intercalates

et al. 2000

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The progressive adsorption of N-methylformamide (NMF) onto Ca-, Mg-, and Na-exchanged Wyoming bentonite (M n+ -SWy-2) together with its subsequent thermal desorption has been studied using a variety of complementary techniques. The derivative thermograms (DTG) for the desorption of NMF from M n+ -SWy-2 exhibit three maxima at temperatures which depend on the exchange cation. In Mg-SWy-2 these maxima occur at 130, 200, and 400 °C, whereas in Na-SWy-2 they occur at 100, 150, and 190 °C. Each of these maxima has been assigned to different sites and/or environments for sorbed NMF using variable temperature-X-ray diffraction (VT-XRD) and variable temperature-diffuse reflectance infrared Fourier transform spectroscopy (VT-DRIFTS). Each fully loaded M n+ -SWy-2/NMF complex has two layers of NMF in the gallery, which decreases to a single layer prior to the complete removal of NMF from the complex. The temperatures at which major weight losses occur coincide with decreases in the interlayer spacing. VT-DRIFTS has shown that at low temperatures NMF was removed from NMF clusters, similar to those in liquid NMF, while at high temperatures the NMF molecules are firmly bound and directly coordinated to the exchangeable cations. Unusual shifts in the C-H and N-H absorption bands were observed, indicating a unique orientation of these groups, which probably reflects their keying into the hexagonal cavities of the tetrahedral sheet of the aluminosilicate layer.

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“…One possible explanation is preferential solvation of LiCl by water, even though the interaction of a lithium cation with the carbonyl oxygen is considered to be stronger than the one with water oxygen. 12,13 Another possible explanation for the precipitation phenomenon is the formation of a mixed solvent shell [Li(H 2 O) x -(DMAc) y ]Cl, 14 which would not have such a high affinity for the hydroxyl groups, as compared to the pure LiCl/DMAc complex. This will be discussed later on in more details.…”

Section: (B) Phase Diagrams Of Samples With Different Water Contentmentioning

confidence: 99%

The investigation of the influence of water and temperature on the LiCl/DMAc/cellulose system

Chrapava

Touraud

Rosenau³

et al. 2003

Phys. Chem. Chem. Phys.

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Status of a Comprehensive Validation of the Navy's F/A-18A/B/C/D Aerodynamics Model.

Cited by 4 publications

References 0 publications

Cations Bind Only Weakly to Amides in Aqueous Solutions

Cations Bind Only Weakly to Amides in Aqueous Solutions

Thermal and Spectroscopic Characterization of N-Methylformamide/Ca-, Mg-, and Na-Exchanged Montmorillonite Intercalates

The investigation of the influence of water and temperature on the LiCl/DMAc/cellulose system

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