Computational characterization of isomeric C4H2O systems: Thermochemistry,vibrational frequencies,and optical spectra for butatrienone,ethynyl ketene,butadiynol, and triafulvenone

Species of empirical formula C₄H₂O have been invoked either as elusive intermediates in flames or oxidations on heterogeneous catalysts, or as long‐lived species in the interstellar medium. Butatrienone has been characterized experimentally, but isomers ethynyl ketene, butadiynol, and trifulvenone have been described only by computational modeling. Triafulvenone is of special interest as the ketene analog of the carbonyl compound cyclopropenone; both species contain seriously strained three‐membered rings. In contrast to cyclopropenone, which is detected in the interstellar medium, triafulvenone continues to elude experimental capture. The contrast is attributed to a degree of aromatic stabilization in cyclopropenone and anti‐aromatic destabilization in triafulvenone. In this report, we characterize the structure, vibrational and electronic spectra, and thermochemistry for triafulvenone and three of its isomers, butatrienone, ethynyl ketene, and butadiynol to assist experimental detection of these elusive species. Our calculations have shown that triafulvenone is the least stable of these four isomers; even the well‐known butatrienone, is not the most stable. The so far undetected ethynyl ketene is thermodynamically the most stable of these isomers. To facilitate experimental detection of these species we provide vibrational frequencies calculated using both B3LYP/cc‐pVTZ and MP2/cc‐pVTZ level model chemistry corrected for anharmonicity including the possibility that the spectra may include overtones and combination bands for these species The regions of intense IR absorption and most important frequencies are also underlined for all the species involved. To guide the search for short‐lived C₄H₂O species, we also characterize the optical spectrum. © 2015 Wiley Periodicals, Inc.     

Fine Spectra of Tridiagonal Toeplitz Matrices

Ukrainian Mathematical Journal - The fine spectra of n-banded triangular Toeplitz matrices and (2n+1)-banded symmetric Toeplitz matrices were computed in (M. Altun, Appl. Math. Comput., 217,...     

Monolithic methacrylate packed 96-tips for high throughput bioanalysis

In the pharmaceutical industry the growing number of samples to be analyzed requires high throughput and fully automated analytical techniques. Commonly used sample-preparation methods are solid-phase extraction (SPE), liquid–liquid extraction (LLE) and protein precipitation. In this paper we will discus a new sample-preparation technique based on SPE for high throughput drug extraction developed and used by our group. This new sample-preparation method is based on monolithic methacrylate polymer as packing sorbent for 96-tip robotic device. Using this device a 96-well plate could be handled in 2–4 min. The key aspect of the monolithic phase is that monolithic material can offer both good binding capacity and low back-pressure properties compared to e.g. silica phases. The present paper presents the successful application of monolithic 96-tips and LC–MS/MS by the sample preparation of busulphan, rescovitine, metoprolol, pindolol and local anaesthetics from human plasma samples and cyklophosphamid from mice blood samples.     

Combined experimental and theoretical studies on the vibrational spectra of 2-quinolinecarboxaldehyde

Combined experimental and theoretical studies have been performed on the structure and vibrational spectra (IR and Raman spectra including far region) of 2-quinolinecarboxaldehyde. Hartree-Fock (HF) and density functional B3LYP calculations have been employed with the 6-311++G(d,p) basis set for investigating the structural and spectroscopic properties of two possible aldehyde rotamers of 2-quinolinecarboxaldehyde. When the O atom of the aldehyde is farther away than the nitrogen atom of the quinoline, 2-quinolinecarboxaldehyde has the lowest possible energy, and thus is in its ground state. The computed vibrational frequencies of this lowest energy rotamer agree also slightly better than those of the higher energy rotamer with the experimental frequencies after the computed frequencies are scaled.     

Fixed point theorems for weak contractions in the sense of Berinde on partial metric spaces

In this paper, we introduce the notion of $(\delta ,L)$ weak contraction and $(\phi ,L)$ weak contraction in the sense of Berinde in partial metric space. Then we give some fixed point results in partial metric space using these new concepts.     

Effect of natural gas usage on indoor radon levels

Effect of natural gas usage on indoor radon concentrations were investigated in dwellings in four counties of ?zmir municipality using LR-115 Type II cellulose nitrate films. The dwellings were separated two groups: natural gas user and non-user. Indoor radon levels were found higher in natural gas using dwellings. Also, indoor radon levels were evaluated in terms of concentrations and annual effective dose. Indoor radon concentrations were found between 22.8 and 707.8 Bq m^?3 and highest concentrations were determined in kitchen in third floor of Bornova dwellings. Indoor radon concentrations in kitchens were found higher than the living rooms. On the other hand, opposite results obtained for annual effective dose, because of very short occupancy period of the kitchens.     

A photoreactive small-molecule probe for 2-oxoglutarate oxygenases

2-oxoglutarate (2-OG)-dependent oxygenases have diverse roles in human biology. The inhibition of several 2-OG oxygenases is being targeted for therapeutic intervention, including for cancer, anemia, and ischemic diseases. We report a small-molecule probe for 2-OG oxygenases that employs a hydroxyquinoline template coupled to a photoactivable crosslinking group and an affinity-purification tag. Following studies with recombinant proteins, the probe was shown to crosslink to 2-OG oxygenases in human crude cell extracts, including to proteins at endogenous levels. This approach is useful for inhibitor profiling, as demonstrated by crosslinking to the histone demethylase FBXL11 (KDM2A) in HEK293T nuclear extracts. The results also suggest that small-molecule probes may be suitable for substrate identification studies.     

Deubiquitinating Enzyme Specificity for Ubiquitin Chain Topology Profiled by Di-Ubiquitin Activity Probes

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Surface modified polypropylene pipette tips packed with a monolithic plug of adsorbent for high-throughput sample preparation

UV-initiated poly(butyl methacrylate-ethylene glycol dimethacrylate) porous polymer monoliths were prepared in situ in polypropylene-based pipette tips for high-throughput sample preparation. Prior to the in situ polymerization, the surface of the PP tips was modified. In this work, two different surface modification approaches were tested for this purpose. First the photoinitiator benzophenone was used to generate radicals at the surface of PP by hydrogen abstraction. In the second modification approach, a thin layer of a polymer was directly grafted to the surface. The effect of surface modification was measured by contact angle measurements of a drop of water at the surface. As a result of the surface modification, scan electron microscopy images indicate a covalent attachment of the monolith to the wall of the pipette tip. Pipette tips modified with 5% BP in methanol and packed with a plug of monolith were further evaluated for high-throughput sample preparation. Using a liquid handling system, the extraction performance of packed pipette tips was tested for the analysis of ropivacaine in plasma samples. The recovery and reproducibility results were in accordance with internationally accepted criteria for qualitative and quantitative analysis of the test substance, ropivacaine.