Intercalation of α,ω-alkyldiamines in layered α-zirconium phosphate and the inclusion behaviour of some of the intercalates obtained

The paper reports a study on the intercalation mechanism of NH₂(CH₂) _n NH₂ (withn=2, 4, 6, 8, 10) diamines in layered Zr(HOPO₃)₂·H₂O, performed by titrating the host with aqueous solutions of amines at 80°C. The intercalation reactions occur stepwise according to the ‘moving boundary’ model, with the formation of a number of intermediate intercalation compounds of formula Zr(HOPO₃)₂·xNH₂(CH₂) _n NH₂ (0<x<1) before obtaining the fully intercalated ones (x=1). For each diamine the batch titration curve and a diagram of the phases involved in the interaclation reaction are reported. Twenty-two intercalation compounds have been isolated and characterized by their composition, XRD patterns and thermal behaviour, and information on the disposition of the guests within the interlayer region have been derived. At full intercalation the diamines form a monolayer of extended molecules with their axis inclined at 58° to the plane of the sheet. The terminal amino groups are protonated by the —POH groups of the host, thus each diamine binds adjacent layers and, in a sense, transforms a layered structure into a framework structure that may have an accessible or potentially accessible porosity. The intercalation compound Zr(HOPO₃)₂·0.5NH₂(CH₂)₈NH₂ is indeed able to include polar molecules such as water and short chain alkanols.     

Reaction of thiete 1,1-dioxide with α-chlorobenzalphenylhydrazine and methyl phenylhydrazonochloroacetate

Thiete 1,1-dioxide reacts with 2 moles of α-chlorobenzalphenylhydrazine and methyl phenylhydrazonochloroacetate in the presence of triethylamine leading to the pyrazole derivatives 6 and 7 whose structure and mechanism of formation are discussed.     

Numerical analysis of roughness effect on microtube heat transfer

Roughness effect on the heat transfer and pressure loss performances of microscale tubes and channels are investigated through a finite element CFD code. Surface roughness is explicitly modelled through a set of random generated peaks along the ideal smooth surface. Different peak shapes and distributions are considered; geometrical parameters are representative of tubes in the diameter range from 50 to 150 μm. The use of a fine enough mesh allows the direct computation of tube performances under the assumption of incompressible fully developed flow. As a result, a significant increase in Poiseuille number is detected for all of the configurations considered, while the effect of roughness on heat transfer rate is smaller and highly dependent on the tube shape.     

Characterization of phospho-olivines as materials for Li-ion cell cathodes

Solid State Reaction was employed to prepare phospho-olivines LiMPO₄ (where M=Fe, Co) as pure phase and LiNiPO₄ in presence of foreign phases, as cathodic materials for lithiumions batteries. The relationship between structural, morphological and electrochemical properties were investigated in the case of LiFePO₄. Structural investigation has been carried out by means of X-ray powder diffraction (XRPD) and Rietveld refinement. The influence on the morphology of annealing temperature, different flowing gas mixture and addition of ascorbic acid during the synthesis, has been analysed via scanning electron microscopy. The electrochemical cycling performances on LiFePO₄ showed to be positively affected by the modifications of the experimental conditions. Cyclic voltammetry showed a good reversibility during insertion-extraction mechanism, in particular in presence of additives. LiCoPO₄ and LiNiPO₄ are interesting as high voltage cathode materials for Li-ion batteries and have been taken into account, but their electrochemical operating conditions are still to be optimised. In the case of LiNiPO₄ it is very difficult to obtain, by solid state synthesis, suitable purity powders, having a grain size small enough to exploit it usefully as cathodic material for Li-ion cells. Paper presented at the 8th EuroConference on Ionics, Carvoeiro, Algarve, Portugal, Sept. 16 – 22, 2000.     

Micro‐Raman spectroscopy and VP‐SEM/EDS applied to the identification of mineral particles and fibres in histological sections

Histological sections of a patient affected by an important respiratory disease were analysed firstly by optical microscope(OM)—crossed polarisers—to identify the presence of incorporated inorganic particles, with particular attention to the fibrous ones. Then, the particles/fibres that were found were studied both with micro‐Raman spectroscopy and variable‐pressure scanning electron microscopy with energy‐dispersive spectroscopy (VP‐SEM/EDS). The two techniques allowed the in situ characterisation of the inorganic phases without disintegration of the organic matter. Micro‐Raman spectroscopy was able to identify the vibrating chemical groups of the mineral phase associated with the inorganic grain while the crystalline structure was preserved by the biological system. The VP‐SEM/EDS characterisation, defining the elemental chemical composition of the analysed particle/fibre, allowed confirmation of the mineral phase deducible from spectroscopic data or its identification with certainty when the spectroscopic data were not exhaustive. Copyright © 2009 John Wiley & Sons, Ltd.     

Crystallization kinetics of PEO-alkaline perchlorate solutions observed by energy dispersive x-ray diffraction

The crystallization kinetics of poly(ethylene oxide) doped with various alkaline perchlorate salts were measured at room temperature by means of the new energy dispersive x-ray diffraction method for the phase transition. The experimental points of the transformation coordinate were fitted using the phenomenological Liquori-Tripiciano law, the parameters of which were evaluated for each case. The influence of the concentration and of the cation dimensions on the crystallization rate is discussed. Further details about the application of this nonconventional diffractometric technique to polymers are also reported, as is an intuitive model for describing the method.     

Reactivity of 2-methyl-4-(1-pyrrolidinyl)-2H-1,2-benzothiazine 1,1-dioxide towards p-toluenesulphonyl azide

The 2-methyl-2H-1,2-benzothiazin-4-(3H)-one 1,1 dioxide ( 2 ), obtained according to a new, one-pot method, is transformed into the pyrrolidino enamine 3 . Reaction of p-toluenesulphonyl azide with 3 gives, via an unstable triazoline adduct which loses nitrogen, the two isomeric tosylamino derivatives 4 and 5 . The structures have been assigned by exhaustive nmr analysis and some aspects on their formation and chemical behaviour are discussed.     

Screening and identification of major phytochemical compounds in seeds,sprouts and leaves of Tuscan black kale Brassica oleracea (L.) ssp acephala (DC) var. sabellica L.

We report the spectrophotometric determination of total polyphenols, flavonoids, glucosinolates and antioxidant activity in seeds, seedlings and leaves of Tuscan black kale. The highest content of phytochemicals was observed in 10 days sprouts and antioxidant activity was maximum in 2, 4 days seedlings. Identification and characterisation of phytochemicals were performed by mass spectrometry (MS), high resolution and tandem MS with electrospray ionisation mode. Low-molecular-weight metabolites were evidenced in seeds while metabolites at high m/z range were detected in cotyledons and leaves. MS spectra evidenced different phenolic compounds (flavonoid caffeoyl glucose, hydroxycinnamic acid sinapine) and glucosinolates (glucoerucin, glucobrassicin and glucoraphanin) in function of developmental stage; galactolipids ω3 and ω6 were observed in leaves. Identification of stages with the highest phytochemicals content encourages the consumption of black kale sprouts and young leaves. Our research can support food and pharmaceutical industries for production of health promoting products from black kale.     

Combined Experimental and Multivariate Model Approaches for Glycoalkaloid Quantification in Tomatoes

The intake of tomato glycoalkaloids can exert beneficial effects on human health. For this reason, methods for a rapid quantification of these compounds are required. Most of the methods for α-tomatine and dehydrotomatine quantification are based on chromatographic techniques. However, these techniques require complex and time-consuming sample pre-treatments. In this work, HPLC-ESI-QqQ-MS/MS was used as reference method. Subsequently, multiple linear regression (MLR) and partial least squares regression (PLSR) were employed to create two calibration models for the prediction of the tomatine content from thermogravimetric (TGA) and attenuated total reflectance (ATR) infrared spectroscopy (IR) analyses. These two fast techniques were proven to be suitable and effective in alkaloid quantification (R² = 0.998 and 0.840, respectively), achieving low errors (0.11 and 0.27%, respectively) with the reference technique.     

Vibrational spectrum, ab initio calculations, conformational equilibria and torsional modes of 1,3-dichloropropane

Ab initio calculations are reported for three of four possible conformers of 1,3-dichloropropane. The fourth conformer, with Cs symmetry, has a predicted enthalpy difference of more than 1500 cm(-1) from the most stable conformer from each calculation regardless of the basis set used, so there is little chance of observing it. Thus, there is no evidence in the infrared or Raman spectrum of the presence of a fourth conformer. The order of stability given by the ab initio calculations is C2(GG)>C1(AG)>C2v(AA)>Cs(GG'), where A indicates the anti form for one of the CH2Cl groups and G indicates the gauche conformation for the other CH2Cl group relative to the plane of the carbon atoms. Almost every band observed can be confidently assigned to one or another of the conformers. Many observed bands proved to be of a composite nature, with several nearly coincident vibrations of different conformers contributing to the band contour. Nonetheless, a complete assignment of fundamentals is possible for the most stable C2 conformer, and 5 of the fundamentals of the C2v conformer and 13 those of the C1 conformer can be confidently assigned.