Synthesis of new vinylpyridinium salts

This article reports the reactions of salts of 4‐ureylmethylpyridinium and 4‐ethoxycarbonylaminomethylpyridinium with carbonylic compounds, performed with the aim of obtaining new vinylpyridinium salts. These reactions can lead to the formation of both condensation and dimerization products. The type of products formed is conditioned by the nature of the salts and carbonyl groups involved. The interest generated by the condensation products formed lies in their potential cholinergic activity. J. Heterocyclic Chem., 2011.     

About the Earth density and the neutrino interaction

We visit again the problem to extract information about the mass distribution of the Earth using neutrino collisions with the Earth matter. The topic was addressed in several opportunities using different observable related with the neutrino flux arriving to a neutrino telescope like IceCube. In the present work we have used an observable that is weakly dependent of the initial flux. We check the homogeneity hypothesis and fit a simplified Earth model consistent with the observational value of the Earth mass and the inertia moment.     

Kinetics of xylitol fermentation by Candida guilliermondii grown on rice straw hemicellulosic hydrolysate

The fermentation kinetics for the conversion of rice straw hemicellulosic hydrolysate to xylitol by the yeast Candida guilliermondii was evaluated under batch conditions. The fermentation was accomplished in a 1 L working volume stirred-tank reactor with aeration of 1.3 vvm and agitation of 300 rpm (k_La=15/h). The maximum specific rate of xylitol formation (0.12 g/g) was achieved when the specific growth rate was lowered to 1/5 of its highest value. From analysis of the fermentation kinetics, a linear correlation between specific growth rate (μ_x) and specific rate of xylitol formation (q_p) was evident. Based on the Gaden model, this bioprocess was classified as growth-associated production and the relationship between μ_x and q_p can be described by the equation q_p=6.31μ_x.     

Sonochemical Reaction of Bifunctional Molecules on Silicon (111) Hydride Surface

While the sonochemical grafting of molecules on silicon hydride surface to form stable Si–C bond via hydrosilylation has been previously described, the susceptibility towards nucleophilic functional groups during the sonochemical reaction process remains unclear. In this work, a competitive study between a well-established thermal reaction and sonochemical reaction of nucleophilic molecules (cyclopropylamine and 3-Butyn-1-ol) was performed on p-type silicon hydride (111) surfaces. The nature of surface grafting from these reactions was examined through contact angle measurements, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Cyclopropylamine, being a sensitive radical clock, did not experience any ring-opening events. This suggested that either the Si–H may not have undergone homolysis as reported previously under sonochemical reaction or that the interaction to the surface hydride via a lone-pair electron coordination bond was reversible during the process. On the other hand, silicon back-bond breakage and subsequent surface roughening were observed for 3-Butyn-1-ol at high-temperature grafting (≈150 °C). Interestingly, the sonochemical reaction did not produce appreciable topographical changes to surfaces at the nano scale and the further XPS analysis may suggest Si–C formation. This indicated that while a sonochemical reaction may be indifferent towards nucleophilic groups, the surface was more reactive towards unsaturated carbons. To the best of the author’s knowledge, this is the first attempt at elucidating the underlying reactivity mechanisms of nucleophilic groups and unsaturated carbon bonds during sonochemical reaction of silicon hydride surfaces.     

Geometrical patterns of time variable Kadomtsev–Petviashvili (I) equation that models dynamics of waves in thin films with high surface tension

Lump solutions are a prominent option for numerous models of nonlinear evolution. The intention of this research is to explore the variable coefficients Kadomtsev–Petviashvili equation. We auspiciously provide multiple soliton and M-lump solutions to this equation. Additionally, the presented results are also supplied with collision phenomena. Owing of its essential role, we employ appropriate parameter values to emphasis the physical characteristics of the provided results using 3D and contour charts. The outcomes of this work convey the physical characteristics of lump and lump interactions that occur in many dynamical regimes.