Boundary value problems for differential equations with fractional derivatives

This paper is devoted to the spectral analysis of the operators generated by differential equations of second order with fractional derivatives in lower terms and boundary conditions of Sturm–Liouville type.     

A domino approach for the synthesis of naphtho[2,1-b]furan-2(1H)-ones from azlactones

A domino approach to naphtho[2,1-b]furan-2(1H)-one derivatives from (Z)-4-arylidene-2-phenyl-5(4)-oxazolones (azlactones) and 2-naphthols catalyzed by p-TSA with reasonably moderate to high yields, has been developed. This protocol illustrates attractive features including a unique and convenient process.     

Rosa platyacantha Schrenk from Kazakhstan—Natural Source of Bioactive Compounds with Cosmetic Significance

Plants belonging to the Rosa genus are known for their high content of bioactive molecules and broad spectrum of healing and cosmetic activities. Rosa platyacantha Schrenk is a wild-type species abundant in the mountainous regions of Kazakhstan. The phytochemical composition as well as the bioactivity of R. platyacantha extracts have not been fully investigated to date. In this study, various parts of R. platyacantha plant, collected in Almaty region, Kazakhstan, were used to prepare five hydroalcoholic extracts (R1–R5). The extracts were compared for the content of phytochemicals and selected biological activities, which are important for the potential cosmetic application of R. platyacantha. Extract R3, prepared from flower buds, showed the most significant antioxidant and tyrosinase inhibitory potential, decreasing the monophenolase and diphenolase activities of tyrosinase. Extract R3 showed also collagenase inhibitory activity and cytotoxicity against human melanoma cells A375, being less cytotoxic for noncancerous skin keratinocytes HaCaT. Analysis of fractions E and F, obtained from R3 extracts, revealed that quercetin, kaempferol, rutin, and their derivatives are more likely responsible for the tyrosinase inhibitory properties of R. platyacantha extracts.     

Network deployment of radiation detectors with?physics-based detection probability calculations

We describe a model for deploying radiation detectors on a transportation network consisting of two adversaries: a nuclear-material smuggler and an interdictor. The interdictor first installs the detectors. These installations are transparent to the smuggler, and are made under an uncertain threat scenario, which specifies the smuggler??s origin and destination, the nature of the material being smuggled, the manner in which it is shielded, and the mechanism by which the smuggler selects a route. The interdictor??s goal is to minimize the probability the smuggler evades detection. The performance of the detection equipment depends on the material being sensed, geometric attenuation, shielding, cargo and container type, background, time allotted for sensing and a number of other factors. Using a stochastic radiation transport code (MCNPX), we estimate detection probabilities for a specific set of such parameters, and inform the interdiction model with these estimates.     

Formic Acid,a Ubiquitous but Overlooked Component of the Early Earth Atmosphere

Terrestrial volcanism has been one of the dominant geological forces shaping our planet since its earliest existence. Its associated phenomena, like atmospheric lightning and hydrothermal activity, provide a rich energy reservoir for chemical syntheses. Based on our laboratory simulations, we propose that on the early Earth volcanic activity inevitably led to a remarkable production of formic acid through various independent reaction channels. Large-scale availability of atmospheric formic acid supports the idea of the high-temperature accumulation of formamide in this primordial environment.     

The influence of the substituent [PhNHNH– and EtN(NH2)–] on the N-thiophosphorylated thiosemicarbazides RC(S)NHP(S)(OiPr)2 crystal design

Two N-thiophosphorylated thiosemicarbazides of the common formula RC(S)NHP(S)(OiPr)₂ [R = PhNHNH- (1); EtN(NH₂)- (2)] have been synthesized and characterized by IR, ¹H and ³¹P spectroscopy, and the single crystal X-ray diffraction method. Single crystal X-ray diffraction studies showed the thiosemicarbazides form both intra- and intermolecular hydrogen bonds, which in turn lead to polymeric chain formation. Moreover, according to the X-ray data of the phenylsubstituted thiosemicarbazide, the formation of intermolecular H?η⁶-phenyl interactions were established.     

Electron beam-accelerated aggregation of formvar film macromolecules

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Spin crossover in tetranuclear cyanide-bridged iron(II) square complexes: a theoretical study

Spin crossover in a series of six cyanide-bridged iron(II) tetranuclear square complexes was analyzed using density functional theory (DFT) methods. As the spin crossover between the low-spin (LS) and high-spin (HS) states can occur only for two of four iron ions, we characterized energetically and structurally the [LS-LS], [HS-LS], and [HS-HS] spin-state isomers. For all studied complexes, the energy of the mixed [HS-LS] spin state does not deviate essentially from the halfway point between the energies of homogeneous spin states, thereby satisfying the conditions for an one-step transition between the [LS-LS] and [HS-HS]. This fact reflects the weak elastic coupling between the environments of transiting centers. The two-step spin transition observed in one complex can appear only due to the crystal packing effects. We also evaluated the strength of exchange coupling between the paramagnetic ions in the [HS-HS] state.