Antifungal activity, toxicity and chemical composition of the essential oil of Coriandrum sativum L. fruits

The aims of this study were to test the antifungal activity, toxicity and chemical composition of essential oil from C. sativum L. fruits. The essential oil, obtained by hydro-distillation, was analyzed by gas chromatography/mass spectroscopy. Linalool was the main constituent (58.22%). The oil was considered bioactive, showing an LC?? value of 23 μg/mL in the Artemia salina lethality test. The antifungal activity was evaluated against Microsporum canis and Candida spp. by the agar-well diffusion method and the minimum inhibitory concentration (MIC) and the minimum fungicidal concentration (MFC) were established by the broth microdilution method. The essential oil induced growth inhibition zones of 28 ± 5.42 and 9.25 ± 0.5 for M. canis and Candida spp. respectively. The MICs and MFCs for M. canis strains ranged from 78 to 620 and 150 to 1,250 μg/mL, and the MICs and MFCs for Candida spp strains ranged from 310 to 620 and 620 to 1,250 μg/mL, respectively. C. sativum essential oil is active in vitro against M. canis and Candida spp. demonstrating good antifungal activity.     

DC-biased AC-electrokinetics: a conductivity gradient driven fluid flow

This paper studies the principles of fluid flow manipulation based on DC-biased AC-electrokinetics. This method makes use of planar parallel electrodes in a microfluidic channel in contact with an electrolyte solution, with a DC biased AC electrical signal applied to the electrode pair. Due to the application of DC bias, incipient Faradaic electrolytic reactions take place resulting in an increase of the ionic content of the bulk solution. The ionic content was found to be dissimilar at the cathodic and anodic sides of the channel and a conductivity difference of approximately 10% was measured for 2 V(DC). Fluid flow is generated by the action of the DC biased AC electric signal acting on the transverse conductivity gradient generated across the microchannel. The induced flow in the form of vortex was characterized experimentally and the results substantiated theoretically. The velocity of the induced flow vortex under the employed experimental conditions was ~600 to 700 μm s(-1) which is faster than those obtained in conventional AC-electroosmosis and AC-electrothermal types of flows.     

Connected size Ramsey number for matchings vs. small stars or cycles

The notation \(F\rightarrow (G,H)\) means that if the edges of F are colored red and blue, then the red subgraph contains a copy of G or the blue subgraph contains a copy of H. The connected size Ramsey number \(\hat{r}_c(G,H)\) of graphs G and H is the minimum size of a connected graph F satisfying \(F\rightarrow (G,H)\). For \(m \ge 2,\) the graph consisting of m independent edges is called a matching and is denoted by \(mK_2\). In 1981, Erdös and Faudree determined the size Ramsey numbers for the pair \((mK_2, K_{1,t})\). They showed that the disconnected graph \(mK_{1,t} \rightarrow (mK_2,K_{1,t})\) for \( t,m \ge 1\). In this paper, we will determine the connected size Ramsey number \(\hat{r}_c(nK_2, K_{1,3})\) for \(n\ge 2\) and \(\hat{r}_c(3K_2, C_4)\). We also derive an upper bound of the connected size Ramsey number \(\hat{r}_c(nK_2, C_4),\) for \(n\ge 4\).     

Base-specific and enantioselective studies for the DNA binding of iron(II) mixed-ligand complexes containing 1,10-phenanthroline and dipyrido[3,2-a:2',3'-c]phenazine

Base specificity and enantioselectivity for the DNA binding of [Fe(phen)2(dppz)]2+ (phen=1,10-phenanthroline and dppz=dipyrido[3,2-a:2',3'-c]phenazine) have been studied by determining the equilibrium binding constant (Kb) of the iron(II) complex to calf thymus DNA (ct-DNA), poly[(dA-dT)2], poly[(dG-dC)2] and poly[(dI-dC)2] using spectrophotometric titration and by monitoring the CD spectral profile of the iron(II) complex in the presence and absence of different types of DNA using circular dichroism (CD) spectroscopy, respectively. It has been shown that [Fe(phen)2(dppz)]2+ prefers to intercalate into the A-T and I-C sequences of poly[(dA-dT)2] and poly[(dI-dC)2] rather than into the G-C sequences of poly[(dG-dC)2] or into the base pairs of ct-DNA. In contrast to previous reports, it is a surprising observation that the enantioselectivity of the DNA binding for [Fe(phen)2(dppz)]2+ is base-dependent in nature. The Delta-enantiomer of [Fe(phen)2(dppz)]2+ is preferentially intercalated into the base pairs of poly[(dG-dC)2] or ct-DNA as indicated by its CD spectral profiles. On the other hand, the Lambda-enantiomer of [Fe(phen)2(dppz)]2+ is favorably intercalated into poly[(dA-dT)2] or poly[(dI-dC)2] as suggested by the opposite CD spectral profile. This preferential binding of Lambda-[Fe(phen)2(dppz)]2+)for the A-T sequence may be attributed to the fact that the binding site for the A-T sequence is relatively facile and thus the steric effect caused by the ancillary (non-intercalated) phen ligands is alleviated. The degree of enantioselectivity represented by inversion constants (Kinv) decreases as the salt concentration in the solution increases, indicating that electrostatic interaction is also operating in the ct-DNA-binding events of the iron (II) complex.     

High-density encapsulation of Fe3O4 nanoparticles in lipid vesicles

We report a morphological study of the encapsulation of 12-nm Fe3O4 nanoparticles (NPs) in large unilamellar vesicles of dipalmitoylphosphatidylcholine (DPPC). Preparation was done by reverse-phase evaporation. Phase behavior of the NP-lipid system was studied so that the loading of NPs in vesicles could be maximized. Increasing NP concentration significantly affects the resulting lipid morphology in a manner similar to increasing lipid concentration. Optimal production of high-density NP-loaded vesicles (HNLVs) requires temperatures of 50 degrees C, higher than the main phase transition (Tm) of DPPC. The formation of fully enclosed HNLVs requires incubation times of at least hours.     

Initial Carbon−Carbon Bond Formation during the Early Stages of Methane Dehydroaromatization

Methane dehydroaromatization (MDA) is among the most challenging processes in catalysis science owing to the inherent harsh reaction conditions and fast catalyst deactivation. To improve this process, understanding the mechanism of the initial C−C bond formation is essential. However, consensus about the actual reaction mechanism is still to be achieved. In this work, using advanced magic-angle spinning (MAS) solid-state NMR spectroscopy, we study in detail the early stages of the reaction over a well-dispersed Mo/H-ZSM-5 catalyst. Simultaneous detection of acetylene (i.e., presumably the direct C−C bond-forming product from methane), methylidene, allenes, acetal, and surface-formate species, along with the typical olefinic/aromatic species, allow us to conclude the existence of at least two independent C−H activation pathways. Moreover, this study emphasizes the significance of mobility-dependent host–guest chemistry between an inorganic zeolite and its trapped organic species during heterogeneous catalysis.     

Well‐Defined Single‐Site Monohydride Silica‐Supported Zirconium from Azazirconacyclopropane

The silica‐supported azazirconacyclopropane ?SiOZr(HNMe₂)(η²‐NMeCH₂)(NMe₂) ( 1 ) leads exclusively under hydrogenolysis conditions (H₂, 150 °C) to the single‐site monopodal monohydride silica‐supported zirconium species ?SiOZr(HNMe₂)(NMe₂)₂H ( 2 ). Reactivity studies by contacting compound 2 with ethylene, hydrogen/ethylene, propene, or hydrogen/propene, at a temperature of 200 °C revealed alkene hydrogenation.