Effect of solvent media and condensed benzene rings on thermochemical behaviour of dibenzo-18-crown-6 in solution

The specific and non-specific interactions of twelve activated carbon cloth samples prepared from commercial cotton fabric, and that present different activation degrees are studied through the determination of immersion enthalpies in CCl₄ and H₂O, and in aqueous solutions of NaOH and HCl. The immersion enthalpies found for the solvents CCl₄ and H₂O are in a range of 5.49–45.84 and 1.77–7.76 J g⁻¹, respectively. The enthalpic values for the materials in aqueous solutions of NaOH and HCl, allow characterizing the chemical surface of these materials, which are in a range of 6.63 and 21.49 J g⁻¹, finding through them important relations in company with other characterizing techniques used in the study of these materials.     

Instrumental neutron activation analysis of Moroccan geological samples using the k0-standardization method

Instrumental neutron activation analysis (INAA) for traces and major elements of several geological samples from “Zgounder” region in Morocco was performed utilizing the k ₀-standardization method. Sample irradiation has been done by the 250 kW Triga Mark II reactor at Jozef Stefan Institute in Slovenia. Due to its accuracy, sensitivity and specificity, the k ₀-standardization method is the most suitable method for non-destructive multielement analysis mainly for trace elements in rocks. It requires an accurate knowledge of the parameters of the irradiation facilities and other instrumentation parameters. It is an absolute standardization method, where the absolute nuclear data are replaced by a nuclear constant, the k ₀-factor, determined experimentally with high accuracy. More than 40 elements were determined using about 30-second short and about 7-hour long irradiations. Gamma-rays emitted from the irradiated samples have been determined by a high purity germanium detector. Accuracy was assessed using the standard reference material AGV-1. This was less than 1% for major elements and about 5% for traces. This revised version was published online in July 2006 with corrections to the Cover Date.     

Kinetics and mechanism of hydrolysis of acetamides in metal-ion redox systems

Summary The hydrolysis ofN-methylacetamide andN,N-dimenthylacetamide in the presence of cobalt(III) and cerium(IV) has been studied in perchloric acid in the range 10–50° C. The reduction of metal ions and the hydrolysis of amides are very slow processes. However, it appears that reduction of metal ion is coupled with the hydrolysis of amides in such a way as to give enhanced rates for the two processes. The reaction requires one mole of the metal ion for one mole of amide. The rate is proportional to the acid concentration and is independent of ionic strength. Activation parameters have been calculated and reaction mechanisms proposed.     

Pottery analysis using PIXE,neutron activation,scanning electron microscopy and X-ray fluorescence techniques

Potsherds were analyzed chemically by four different techniques. Results are compared for many elements. The effect of temper appears as a problem because of the inhomogeneity of the bulk. PIXE and neutron activation are powerful and complementary methods to obtain element concentrations for proveniance studies. Also scanning electron microscopy and the electron microprobe are very useful to detect and analyze the tempers. Thus it is possible to gather data on the potter technology. In conclusion the use of a proton microprobe seems to be a promising instrument for versatile analyses.     

Synthesis, Cation-Binding and Optical Spectral Studies of Photoemmitive Benzothiazole Crown Ethers

Crown ethers 1–4, encompassing a photoemittive benzothiazole chromophore have been synthesised using standard protocols. Alkali metal picrate extraction profiles reveal that compared to the known crown ethers, benzothiazole benzo-15-crown-5 1 and benzothiazole dibenzo-18-crown-6 3 exhibit relatively higher % extraction for K⁺ than Na⁺ ions. The UV-visible and fluorescence spectra of 1–4, in comparison to their neutral forms were found to be red shifted on protonation due to enhanced intramolecular charge transfer transition. The ortho-substituted benzothiazole crowns 2–4 showed higher Stokes shifts compared to the para analog 1 in the presence of CF₃CO₂H, presumably due to H-bond assisted conformational restriction. No changes were noticeable in the absorption spectra in the presence of alkali metal ions. Even, fluorescence properties of 1–4 were not found to be drastically perturbed by these ions. While 1 exhibited slight quenching at alkali metal ion concentration over 10-folds with respect to that of 1, interestingly, 2–4 showed a slight enhancement of fluorescent intensity at least up to 10-fold concentration of metal ions over those of 2–4. Further increase of metal ion concentrations produces quenching effects. This behavior has been tentatively explained by invoking electrostatic interaction between these cations and the benzothiazole nitrogen ligand.     

A characterization for Adams-type boundedness of the fractional maximal operator on generalized Orlicz–Morrey spaces

In the present paper, we shall give a characterization for weak/strong Adams-type boundedness of the fractional maximal operator on generalized Orlicz–Morrey spaces.     

Real-space visualization of intercalated water phases at the hydrophobic graphene interface with atomic force microscopy

The phase behavior of water is a topic of perpetual interest due to its reinai kable anomalous properties and importance to biology,material science,geoscience,nanoscience,etc.It is predicted confined water at interface can exist in large amounts of crystalline or amorphous states.However,the experimental evidence of coexistence of liquid water phases at interface is still insufficient.Here,a special folding few-layers graphene film was elaborate prepared to form a hydrophobic/hydrophobic interface,which can provide a suited platform to study the structure and properties of confined liquid water.The real-space visualization of intercalated water layers phases at the folding interface is obtained using advanced atomic force microscopy(AFM).The folding graphene interface displays complicated internal interfacial characteristics.The intercalated water molecules present themselves as two phases,low-density liquid(LDL,solid-like)and high-density liquid(HDL,liquid-like),according to their specific mechanical properties taken in two multifrequency-AFM(MF-AFM)modes.Furthermore,the water molecules structural evolution is demonstrated in a series of continuous MF-AFM measurements.The work preliminary confirms the existence of two liquid phases of water in real space and will inspire further experimental work to deeply understanding their liquid dynamics behavior.     

Tributyltin(IV)[3‐(3′,5′‐dimethylphenylamido)propanoate] as a potent HCV inhibitor,its delivery study,controlled release and binding sites using CTAB as a standard cell membrane

Gaussia luciferase assay was used to measure the anti‐hepatitis C (anti‐HCV) potency of tributyltin(IV)[3‐(3′,5′‐dimethylphenylamido)propanoate] in infected Huh 7.5 cells (human hepatocellular cell). Interaction of the organotin(IV) complex with cetyl N,N,N‐trimethylammonium bromide (CTAB) micelles was studied using UV–visible and steady‐state florescence spectroscopy. The anti‐HCV study showed a log IC₅₀ value of 0.96 nm for the complex. The complex–CTAB interaction parameter showed that partition of the complex from bulk water to the CTAB micelle was a spontaneous process, and the red shift in visible spectra of the complex confirmed its increased solubility into micelles. Copyright © 2013 John Wiley & Sons, Ltd.