Accuracy of speaker verification is high under controlled conditions but falls off rapidly in the presence of interfering sounds. This is because spectral features, such as Mel-frequency cepstral coefficients (MFCCs), are sensitive to additive noise. MFCCs are a particular realization of warped-frequency representation with low-frequency focus. But there are several alternative, potentially mor...

Sodium-ion batteries (SIBs) have been widely explored by researchers because of their abundant raw materials, uniform distribution, high-energy density and conductivity, low cost, high safety. In recent years, theoretical calculations experimental studies on SIBs increasing, the applications results first-principles aroused extensive interests worldwide. Herein, authors review functional (DFT) ...

The size at which nonplanar isomers of neutral, pristine gold nanoclusters become energetically favored over planar ones is still debated amongst theoreticians and experimentalists. Spectroscopy confirms planarity is preferred at sizes up to Au7, however, starting with Au8, the uncertainty remains for larger nanoclusters. Au8 computational studies have had different outcomes: the planar D4h "cl...

The synthesis of the new diethyl ammonium salt of diethylammonium(E)-5-(1,5-bis(4-fluorophenyl)-3-oxopent-4-en-1-yl)-1,3-diethyl-4,6-dioxo-2-thioxohexaydropyrimidin-5-ide 3 via a regioselective Michael addition of N,N-diethylthiobarbituric acid 1 to dienone 2 is described. In 3, the carboanion of the thiobarbituric moiety is stabilized by the strong intramolecular electron delocalization with t...

A conformational analysis of the methanesulfonamide-N,N'-1,2-ethanediylbis (msen) was performed by using vibrational and NMR spectroscopies as well as theoretical computations. The possible stable conformers of msen on its potential energy surface were investigated by semi-empirical PM5 method and appropriate structures were defined with B3LYP hybrid density functional theory (DFT) method along...

The acidity constants Ka1 and Ka2 of 2-(5-mercapto-1,3,4-thiadiazol-2-ylthio)acetic acid have been determined both by experimental and theoretical methods. pKa computations at B3LYP/6-311+G(d,p) level of theory were carried out for the two tautomeric forms, thiol and thione, of the above-mentioned acid. Comparisons between the experimental and theoretical values led to the establishing of the m...

Structural properties of two representative (4,4) armchair and (6,0) zigzag boron phosphide nanotubes (BP-NTs) are studied by density functional theory (DFT) calculations. To this aim, both structures and also the equivalent layer-like structures are individually optimized; afterwards, the boron-11 and phosphorous-31 chemical shielding (CS) tensors are calculated in the optimized structures. Th...

The electronic ground states of the recently synthesized stable nonacene derivatives (J. Am. Chem. Soc. 2010, 132, 1261) are open-shell singlets with a polyradical nature instead of closed-shell singlets as originally assumed, according to the unrestricted broken spin-symmetry density functional theory (UBS-DFT) computations (at B3LYP/6-31G*). It is the bulky protecting groups, not the transfer...

A combined experimental and theoretical study was conducted on numerous higher fullerene anions with different sizes and shapes, C76-D2, C78-C2v, C78-D3, C84-D2, and C84-D2d. The corresponding fullerenes were reduced by lithium metal to diamagnetic multiply charged anions. The centers of gravity of the 13C NMR spectra of all the multiply charged anions were deshielded, relative to those of the ...

Large scale atomistic simulations are feasible only with classical effective potentials. Nevertheless, even for classical simulations some ab-initio computations are often necessary, e.g. for the development of potentials or the validation of the results. Ab-initio and classical simulations use rather different algorithms and make different requirements on the computer hardware. We present perf...