To elucidate the mechanism of DNA strand breaks by low-energy electrons (LEE), theoretical investigations of the LEE attachment-induced C(5')-O(5') sigma bond breaking of pyrimidine nucleotides (5'-dCMPH and 5'-dTMPH) were performed by using the B3LYP/DZP++ approach. The results indicate that the pyrimidine nucleotides are able to capture electrons characterized by near-0-eV energy to form elec...

■ Abstract On laboratory time scales, the energy landscape of a weak bond along a dissociation pathway is fully explored through Brownian-thermal excitations, and energy barriers become encoded in a dissociation time that varies with applied force. Probed with ramps of force over an enormous range of rates (force/time), this kinetic profile is transformed into a dynamic spectrum of bond rupture...

background: laser ablation has been suggested as an alternative method to acid etching; however, previous studies have obtained contrasting results. the purpose of this study was to compare the shear bond strength (sbs) and fracture mode of orthodontic brackets that are bonded to enamel etched with acid and erbium-doped yttrium aluminum garnet (er:yag) laser. materials and methods: in this expe...

In the present work, the substituent effect on the strength of H-bonds in the guanine – cytosine base pair was studied when the substituents are connected to the guanine base through a phenyl ring. In this study, guanine was substituted in the H8 and H9 positions by electron donating (ED) and electron withdrawing (EW) groups mediated by a phenyl ring in the gas phase. The calculations were perf...

In the present study, the effect of post-rolling annealing heat treatment on the formation of intermetallic compounds between Al-Cu strips, in the presence of nickel coating on the Cu strips, was investigated. In addition, the effect of post-rolling annealing and intermetallic compounds on the bond strength of Al-Cu strips was evaluated. In order to prepare samples, Cu strips were coated with n...

Thermodynamic stability of graphene hydrides increases in an approximately linear way with the numbers of π-bonds they contain. Thus, π-bond maximization is the primary driving force for hydrogen addition reactions of graphene. The previously reported thermal preference of sp(2)/sp(3)-phase separation of graphene hydrides is a straightforward effect of π-bond maximization. Although not well app...

The valence bond-like picture of the chemical bond is deeply rooted into the qualitative general chemistry framework and electron-pair covalent bonds are often considered as the “standard” chemical bond. Conversely, odd-electron and multicenter bonds are seen as anomalous, unrepresentative, or just different types of bonds. In this work, the powerful Interference Energy Analysis (IEA) approach ...

We used dispersion-corrected density functional theory (DFT-D3) calculations to investigate the initial C-H bond cleavage of propane σ-complexes adsorbed on the PdO(101) surface. The calculations predict that propane molecules adsorbed in η(1) configurations can undergo facile C-H bond cleavage on PdO(101), where the energy barrier for C-H bond activation is lower than that for desorption for e...

The influence of cation-π interactions on the strength and nature of intramolecular O...H hydrogen bond has been investigated by quantum chemical calculations in orthohydroxy benzaldehyde (HBA) compound. Ab initio calculations have been performed at MP2/6-311++G** level of theory. Vibrational frequencies and physical properties such as chemical potential and chemical hardness of these compounds...

A square-cell lattice is considered consisting of point masses at its knots connected by linearly elastic bonds of nonzero density. Steady-state crack propagation is studied. A general relation between the knot mass and the bond mass is assumed; however, a detailed analytical examination is made for the material-bond lattice with no concentrated masses. It is assumed that the crack divides the ...