Effect Of Carbonyl Research Articles

A “two-step” assay based on electro-activation for rapid determination of methylglyoxal in honey and beer

Methylglyoxal (MGO), a dicarbonyl compound in living organism, food and environment, has been associated with disease diagnosis and human health. The current electrochemical detection methods rely on the use of advanced materials. In this work, a non-advanced materials “two-step” assay including electrode electro-activation and MGO detection was developed. In the section of electro-activation, an activation method of GCE for MGO detection was established; and the composition changes on GCE surface caused by electro-activation, including functional groups and surface defects, have been carefully studied. The effect of carbonyl and surface defects induced by electro-activation on MGO detection was discussed. In section of MGO detection, the raise of background current caused by electro-activation was minimized by background subtraction; and the effect of interferences can be weakened by adjusting pH. The MGO signal on proposed activated GCE improved 20-fold than bare GCE. The recoveries were 72.38–109.16% in honey and beer, and RSDs were 0.24–9.63% without significant difference with HPLC method and comparable with advanced material modified sensors.

Carbonylation induced by antibiotic and pesticide residues on casein increases its IgE binding and allergenicity

This work aimed to evaluate the effect of carbonylation induced by tetracyclines, β-lactams, fluoroquinolones, and pyrethroids in caseins of bovine origin on their immunoreactivity and allergenicity. Using a spectrophotometric method, ELISA, dot-blot, and an IgE-mediated milk allergy mouse model, we confirmed that antibiotics and pesticides at their maximum residue limit, promoted the in vitro carbonylation of caseins (among 5.0 ± 0.01 and 67.5 ± 0.70 nmol of carbonyl/mg of protein); furthermore, carbonylations greater than 19 nmol significantly increase the in vitro IgE immunoreactivity of caseins (average OD among 0.63–1.50) regarding the negative control (average OD: 0.56). On the other hand, sensitized mice exposed to oxidized caseins showed increased clinical scores (2–5), positive skin tests, and footpad swelling (0.28–0.59 mm) compared to the negative control (1–2; negative skin tests; 0.1 mm, respectively), denoting increased allergenicity. These results suggest that casein carbonylation increases their IgE immunoreactivity and allergenicity, a fact that could be explained by the resistance to the digestion promoted by carbonylation and by conformational changes in the random coil casein structure, which can expose cryptic epitopes or neoepitopes.

The Effect of Carbonyl and Hydroxyl Compounds on Swelling Factor, Interfacial Tension, and Viscosity in CO2 Injection: A Case Study on Aromatic Oils

A factor influencing the effectiveness of CO2 injection is miscibility. Besides the miscible injection, CO2 may also contribute to oil recovery improvement by immiscible injection through modifying several properties such as oil swelling, viscosity reduction, and the lowering of interfacial tension (IFT). Moreover, CO2 immiscible injection performance is also expected to be improved by adding some solvent. However, there are a lack of studies identifying the roles of solvent in assisting CO2 injection through observing those properties simultaneously. This paper explains the effects of CO2–carbonyl and CO2–hydroxyl compounds mixture injection on those properties, and also the minimum miscibility pressure (MMP) experimentally by using VIPS (refers to viscosity, interfacial tension, pressure–volume, and swelling) apparatus, which has a capability of measuring those properties simultaneously within a closed system. Higher swelling factor, lower viscosity, IFT and MMP are observed from a CO2–propanone/acetone mixture injection. The role of propanone and ethanol is more significant in Sample A1, which has higher molecular weight (MW) of C7+ and lower composition of C1–C4, than that in the other Sample A9. The solvents accelerate the ways in which CO2 dissolves and extracts oil, especially the extraction of the heavier component left in the swelling cell.

The effect of carbonyl on the isomerization of a galanthan ring system and total synthesis of (±)-β-lycorane.

Lycorine-type alkaloids are privileged structures in drug development due to their attractive biological activities. In this paper, the carbonyl on the C ring was proved to have played a critical role in stereoselectivity during the synthesis process, and the galanthan skeleton with a cis-B/C ring is more thermodynamically stable in its presence. Furthermore, the total synthesis of (±)-β-lycorane was successfully completed by employing the Michael addition reaction to construct the galanthan skeleton with a trans-B/C ring. This system might be applied to other structural types with similar stereochemistry setting.

Kinetic and mechanism studies of the ozonolysis of three unsaturated ketones

Reaction rate constants and products of 1-octen-3-one, 3-octen-2-one and 4-hexen-3-one with ozone were studied in a 100-L fluorinated ethylene propylene (FEP) Teflon film bag using absolute rate method at 298 ± 1 K and atmospheric pressure. The rate constants were (1.09 ± 0.12) × 10−17, (3.48 ± 0.36) × 10−17 and (5.70 ± 0.60) × 10−17 cm3/(molecule⋅sec), respectively. According to the obtained rate constants, the effects of carbonyl were discussed. The carbonyl group in β position has a net withdrawing effect with respect to an olefinic bond, then causing the decline of rate constants. The quantum chemical calculation was used to explain the results of rate constants. The products of ozonolysis were mainly aldehydes, which have significant influence on the formation of SOA, and hence play an important role in the atmosphere. In this work, we detected the main products of reaction and proposed the reaction mechanism by combining the results of quantum chemical calculations. Atmospheric lifetime for three unsaturated ketones reacted with ozone was 36.4, 11.4 and 6.9 hr for 1-octen-3-one, 3-octen-2-one and 4-hexen-3-one, respectively.

The Effect of Carbonylation on Yellowish Coloration of Replicatively Senescent Dermal Fibroblasts

The Effect of Carbonylation on Yellowish Coloration of Replicatively Senescent Dermal Fibroblasts

Theoretical study on the effect of annelation and carbonylation on the electronic and ligand properties of N-heterocyclic silylenes and germylenes: carbene comparisons begin to break down.

Quantum chemical calculations have been carried out to investigate the effect of annelation and carbonylation on the electronic and ligand properties of N-heterocyclic silylenes and germylenes. The thermodynamic stability of these ligands has been found to increase with annelation, while the reverse is true for carbonylation. This is in sharp contrast to N-heterocyclic carbenes (NHCs) where annelation leads to a decrease in their thermodynamic stabilities. Compared to nonannelated derivatives, annelated and carbonylated ones are found to be weaker σ donors but better π acceptors. The effect of carbonylation is more pronounced than annelation toward increasing the π acidity of these ligands. Carbonylation at the α-position with respect to the N atom attached to the Si/Ge center has been found to be the most effective way of enhancing the π acidity of these ligands. The computed natural charges reveal that electrophilicity increases upon both annelation and carbonylation. The calculated values of (31)P NMR chemical shifts of corresponding phosphinidene adducts of these ligands have been found to correlate well with the π acidity of these Si/Ge centers.

Structures and energies of the tautomers of 1-nitroso-1,2,4-triazol-5-one-2-oxide: New triazol-5-one-n-oxides

Molecular orbital calculations at the DFT-B3LYP/aug-cc-pVDZ level are performed for the possible tautomers of 1-nitroso-1,2,4-triazol-5-one-2-oxide. We have examined the substitution effects of carbonyl, N-oxide, and nitroso groups by comparing the calculated geometries, relative energies, and electrostatic potentials of model molecules. The optimized structures, vibrational frequencies, and thermodynamic values for triazolone-N-oxides are obtained in the ground state. The results show that 1H, 4H tautomers are most stable. Detonation velocity and detonation pressure are evaluated by the Kamlet-Jacob equations based on the predicted density and the calculated heat of explosion. The explosive properties of the designed compounds seem to be promising compared with those of 1,3,5-trinitroperhydro-1,3,5-triazine (D 8.75 km/s, P 34.70 GPa), octahydro-1,3,5,7-tetrnitro-1,3,5,7-tetrazocine (D 9.10 km/s, P 39.3 GPa), and 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (D 9.20 km/s, P 42.0 GPa).

Correction to Microscopic Analysis of Protein Oxidative Damage: Effect of Carbonylation on Structure, Dynamics, and Aggregability of Villin Headpiece

ADVERTISEMENT RETURN TO ISSUEPREVAddition/CorrectionORIGINAL ARTICLEThis notice is a correctionCorrection to Microscopic Analysis of Protein Oxidative Damage: Effect of Carbonylation on Structure, Dynamics, and Aggregability of Villin HeadpieceDrazen Petrov and Bojan Zagrovic*Cite this: J. Am. Chem. Soc. 2014, 136, 5, 2175–2176Publication Date (Web):January 21, 2014Publication History Published online21 January 2014Published inissue 5 February 2014https://doi.org/10.1021/ja412337gCopyright © 2014 American Chemical SocietyRIGHTS & PERMISSIONSACS AuthorChoiceArticle Views393Altmetric-Citations1LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (495 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

N‐Heterocyclic carbene/phosphite synergistically assisted Pd/C‐catalyzed Suzuki coupling of aryl chlorides

An N‐heterocyclic carbene and phosphite synergistically enhanced Pd/C catalyst system has been developed for Suzuki coupling of aryl chlorides and aryl boronic acids from commercially available Pd/C with sterically demanding N,N′‐bis(2,6‐diisopropylphenyl)imidazolylidene and trimethylphosphite. A remarkable increase in catalytic activity of Pd/C was observed when used along with 1 equiv. N,N′‐bis(2,6‐diisopropylphenyl)imidazolium chloride and 2 equiv. phosphite with respect to palladium in appropriate solvents that were found to play a crucial role in Pd/C‐NHC‐P(OR)3‐catalyzed Suzuki coupling. A dramatic ortho‐substitution effect of carbonyl and nitrile groups in aryl chlorides was observed and explained by a modified quasi‐heterogeneous catalysis mechanism. The Pd/C catalyst could be easily recovered from reaction mixtures by simple filtration and only low palladium contamination was detected in the biparyl products. A practical process for the synthesis of 4‐biphenylcarbonitrile has therefore been developed using the N‐heterocyclic carbene/phosphite‐assisted Pd/C‐catalyzed Suzuki coupling. Copyright © 2013 John Wiley & Sons, Ltd.

Electronic and Ligand Properties of Annelated Normal and Abnormal (Mesoionic) N-Heterocyclic Carbenes: A Theoretical Study

The effect of annelation and carbonylation on the electronic and ligating properties of N-heterocyclic carbenes (NHCs) has been studied quantum chemically. The thermodynamic and kinetic stability of these NHCs have been assessed on the basis of their singlet-triplet and HOMO-LUMO gaps respectively. Both annelation and carbonylation have been found to decrease the stability of NHCs. Compared to nonannelated carbenes, annelated and carbonylated carbenes are found to be weaker σ donors but better π acceptors. However, the effect of carbonylation is more pronounced than annelation toward increasing the π acidity of the NHCs. The reactivity of these carbenes has been discussed in terms of nucleophilicity and electrophilicity indices. The calculated values of the relative redox potential and (31)P NMR chemical shifts of corresponding carbene-phosphinidene adducts have been found to correlate well with the π acidity of the NHCs.

Molecular Structure, NMR, HOMO, LUMO, and Vibrational Analysis of O-Anisic Acid and Anisic Acid Based on DFT Calculations

This work deals with the vibrational spectroscopy of O-Anisic acid (OAA) and Anisic acid (AA). The fundamental vibrational frequencies and intensity of vibrational bands were evaluated using density functional theory (DFT) with standard B3LYP/6-31G** method and basis set combinations. The vibrational spectra were interpreted, with the aid of normal coordinate analysis based on a scaled quantum mechanical force field. The infrared and Raman spectra were also predicted from the calculated intensities. The effects of carbonyl and methyl substitutions on the structure and vibrational frequencies have been investigated. Comparison of simulated spectra with the experimental spectra provides important information about the ability of the computational method to describe the vibrational modes. The13C and1H NMR chemical shifts of the DFA and CA molecules were calculated using the gauge-invariant-atomic orbital (GIAO) method in DMSO solution using IEF-PCM model and compared with experimental data.

Changes in CNT-confined water structural properties induced by the variation in water molecule orientation

Using a (8, 8) carbon nanotube (CNT) as a model for nanochannel, we studied the effects of carbonyl (–CO) groups and external electric field on the properties of confined water molecules by molecular dynamics simulation. We analysed the density profiles, the distribution of orientation and the hydrogen bonds of water molecules in the axial and radial directions of the CNT. The results show that –CO groups are more powerful than electric fields on controlling water properties, and property changes induced by –CO groups are less affected by electric fields. Meanwhile, the particular behaviour of water molecules induced by the –CO groups is not limited near the –CO groups, but also expands to the whole CNT.

The effect of carbonyl, carboxyl and hydroxyl groups on the capacitance of carbon nanotubes

The effect of carbonyl, carboxyl and hydroxyl groups on the capacitance of carbon nanotubes

The effect of carbonyl, carboxyl and hydroxyl groups on the capacitance of carbon nanotubes

Concentrated H 2SO 4:HNO 3 mixed acids, air, nitric acid and potassium permanganate were used to oxidize carbon nanotubes (CNTs) to introduce surface functional groups (SFGs) and the effects of the type and amount of SFGs on the electrochemical properties of CNT supercapacitors were investigated. XPS analysis shows that the mixed acid oxidation produces carbonyl (C=O) and the carboxyl (O-C=O) groups, the air oxidation results in hydroxyl and the smallest amount of carbonyl and carboxyl groups, and both the nitric acid and potassium permanganate treatments result in a moderate amount of carbonyl and carboxyl groups. It was found that the specific surface area and pore structures of the four samples are similar and carbonyl and carboxyl groups contribute the most to pseudo-capacitance through a Faradic reaction. In particular, the carbonyl group has a proportional relationship to the capacitance of CNTs. However, the hydroxyl group does not lead to an obvious increase of pseudo-capacitance, but can increase the electric double layer capacitance. The carbonyl and the carboxyl groups are advantageous for fast Faradic reactions to introduce pseudo-capacitance, owing to their lower charge transfer resistance than that of the hydroxyl group.

CONTAMINATION OF CARBON MONOXIDE WITH METAL CARBONYLS: IMPLICATIONS FOR COMBUSTION RESEARCH

In a study on syngas combustion in a swirl-stabilized combustor, red deposits quickly formed on the quartz combustor walls, preventing laser diagnostic measurements. Analysis of the deposit showed that is was composed of iron and nickel. A literature review revealed that typical pressurized cylinders of CO, even at the highest CO purity level, contain up to 100 ppmv of iron pentacarbonyl and somewhat smaller levels of nickel tetracarbonyl. Only semiconductor grade CO stored in aluminum cylinders has sub-ppm levels of carbonyls. The demonstrated strong flame inhibition effect of carbonyls suggests that the use of CO from steel cylinders in combustion experiments may affect studies of flame ignition or extinction, in addition to the effect of particle formation and deposition observed here.

Effect of carbonyls on the reactivity of polyenes in autoxidation

AbstractAutoxidation of the biologically active polyenes β‐carotene, canthaxanthin, retinyl acetate, methyl retinoate, retinal and 3,7,11,11‐tetramethyl‐10,15‐dioxo‐2,4,6,8‐hexadecatetraenal (diketoretinal) in solid amorphous films was investigated. The course of the process was followed by electronic and IR spectroscopy. The overall activation energies were obtained. It was shown that insertion in the polyene molecule of a carbonyl group conjugated with polyene chain results in a drastic decrease in the reactivity towards molecular oxygen. The results are discussed and explained on the basis of radical stabilization energy, ES(R·), as a driving force of the autoxidation process. Semi‐empirical AM1 calculations of ΔHf of some retinyl polyenes and polyenyl radicals were carried out and the C—H bond strengths and ES(R·) values of corresponding polyenyl radicals were evaluated. It was shown that the incorporation of a carbonyl group in the polyene results in a decrease in the overall autoxidation rate due to the decrease in both the initiation and propagation rates. Copyright © 2003 John Wiley & Sons, Ltd.

Crystalline polymer on silica. Geometrical selectivity for azobenzenes through highly-oriented structure

Poly(octadecyl acrylate), ODA n , with a trimethoxysilyl group at one side of the terminal group was immobilized onto porous silica by using the reactive terminal group. The silica-supported ODA n underwent crystalline-to-isotropic phase transition. Interaction between ODA n and azobenzenes were evaluated by retention time in the liquid chromatography using the column packed with silica-supported ODA n . The chromatograph showed complete separation against the geometrical isomers of azobenzenes in methanol–water. The temperature dependence of the separation factor indicated that the selectivity increased with the molecular orientation of ODA n . Effect of carbonyl–π interaction due to the acrylate moiety on the selectivity was examined using seven kinds of p-substituted phenylazobenzenes with various Hammett's substituent constants.

Direct inhibitory effect of CCCP on the Cl(-)-H+ symporter of the guinea pig ileal brush-border membrane.

The effect of carbonyl cyanide-m-chlorophenylhydrazone (CCCP) on Cl- uptake across the brush-border membrane (BBM) was quantified using 36Cl and BBM vesicles from guinea pig ileum. CCCP inhibited only partially both the pH gradient-activated Cl- uptake and Cl-/Cl- exchange activities present in these vesicles. In contrast, CCCP had no effect on the initial (2-30 s) decay rate of an imposed proton gradient, as determined using the pH-sensitive fluorophore pyranine. Taken together, these results strongly indicate that the main action of CCCP does not consist of dissipating any imposed pH gradient but rather in inhibiting directly the pH gradient-activated Cl- uptake and Cl-/Cl- exchange activities characterizing the intestinal BBM. Because these two activities can be explained in terms of a single (homogeneous) random, nonobligatory two-site Cl(-)-H+ symporter, in which Cl-/Cl- exchange occurs by counterflow [F. Alvarado and M. Vasseur. Am. J. Physiol. 271 (Cell Physiol. 40): C1612-C1628, 1996], we developed a new, more general three-site symport model that fully explains the Cl- uptake inhibitions caused by CCCP. This new model postulates the existence of a third, allosteric, inhibitory CCCP-binding site separate from either of the two substrate-binding sites of the Cl(-)-H+ symporter, the Cl(-)-binding and the H(+)-binding sites. Finally, we show that, to explain the partial inhibitions observed, it is necessary to postulate that all the substrate-bound carrier complexes, = C-S, I = C-S, A = C-S, and IA = C-S, where C is carrier, I is inhibitor, S is substrate, and A is activator, can form and be translocated.

The Effect of Carbonyl Containing Terminal Chains on Mesomorphic Properties in 4,4′-Disubstituted Phenylbenzoates and Thiobenzoates 8. Phenylbenzoates Containing Two Carbonyl Containing Terminal Chains

Abstract A variety of phenylbenzoates of the type with both X and Y being the carbonyl containing chains (CH2)nCOR (n = 0 – 1), (CH2)nCO2R and (CH2)nOCOR (R = alkyl chain) in various combinations were synthesized and their mesomorphic properties studied to determine if an additive effect occurs when these chains are incorporated into the same molecule. No reliable additive effect could be found. Instead, clearing temperatures often seemed to be closer to the clearing temperature of the parent single carbonyl containing chain ester with the higher clearing temperature. An attempt was also made to improve the properties of the esters 1 with X or Y being I, F, CN or NO2 by using a carbonyl containing chain as the second substituent and assuming an additive effect. However, such an effect was also not observed in these esters. Smectic C phases were found in some of the esters with X ˭ CN which is rare for compounds containing this substituent.