On the antibacterial activity of roots of Capparis spinosa L

A decoction of Capparis spinosa L. roots, widely used in the traditional folk medicine of southern Italy, was prepared and submitted to antibacterial activity tests, which showed an interesting bacteriostatic activity on the growth of Deinococcus radiophilus. Heterocyclic compounds were also recovered from the chloroformic extract of the roots.     

A novel general route for the preparation of enantiopure imidazolines

A novel procedure for the preparation of enantiopure 1,4-disubstituted 2-imidazolines is reported. Enantiopure beta-amino alcohols are converted into N-hydroxyethylamides, which are reacted with excess thionyl chloride, or with thionyl chloride followed by phosphorus pentachloride to yield N-chloroethylimidoyl chlorides. These intermediates are treated with amines and anilines to produce N-chloroethylamidines, which are converted into imidazolines upon workup with aqueous hydroxide. The method is simple and efficient and has been used to prepare a wide variety of enantiopure imidazolines, in a modular fashion, from readily available amino alcohols.     

Assay for urinary estriol during the menstrual cycle based on extraction by a graphitized carbon black cartridge followed by high-performance liquid chromatography

Summary A high-performance liquid chromatography (HPLC) assay for estriol in nonpregnancy urine is described. After Enzymic hydrolysis, the estriol is extracted from urine by the sorbent trap technique utilizing graphitized carbon black (Carbopack B). After some washing steps, estriol is desorbed by a suitable solvent system. After solvent removal, the sample is injected into an HPLC column for estriol quantification. Analytical recovery of estriol was 96.1%. The precision of the method was 2.6 and 4.9% respectively at 145 and 10.6ng/ml of urine. The limit of sensitivity was set at 0.8 ng/ml of urine. The mean contents of estriol in the follicular and luteal phases were respectively 11.3 and 38.8 ng/ml of urine.Dedicated to Prof. Dr. A. Liberti on the occasion of his 70th birthday.     

Densities and excess molar volumes for binary mixtures of N,N-dimethylformamide+ 1,2-dimethoxyethane

Densities are reported for N,N-dimethylformamide and 1,2-dimethoxyethane binary mixtures at different mole fractions covering the whole miscibility range and at 19 temperatures ranging from –10 to 80°C. The experimental density data have been fitted by empirical relations and the excess volumes by a Redlich-Kister equation. The 11 N,N-dimethylformamide and 1,2-dimethoxyethane adduct appears to be stable throughout the temperature range. A comparison with other DMF containing mixtures is made.     

The hydrothermal decomposition of calcium monosulfoaluminate 14-hydrate to katoite hydrogarnet and β-anhydrite: An in-situ synchrotron X-ray diffraction study

We apply in-situ synchrotron X-ray diffraction to study the transformation of calcium monosulfoaluminate 14-hydrate Ca₄Al₂O₆(SO₄)·14H₂O [monosulfate-14] to hydrogarnet Ca₃Al₂(OH)₁₂ on the saturated water vapor pressure curve up to 250 °C. We use an aqueous slurry of synthetic ettringite Ca₆Al₂(SO₄)₃(OH)₁₂·26H₂O as the starting material; on heating, this decomposes at about 115 °C to form monosulfate-14 and bassanite CaSO₄·0.5H₂O. Above 170 °C monosulfate-14 diffraction peaks slowly diminish in intensity, perhaps as a result of loss of crystallinity and the formation of an X-ray amorphous meta-monosulfate. Hydrogarnet nucleates only at temperatures above 210 °C. Bassanite transforms to β-anhydrite (insoluble anhydrite) at about 230 °C and this transformation is accompanied by a second burst of hydrogarnet growth. The transformation pathway is more complex than previously thought. The mapping of the transformation pathway shows the value of rapid in-situ time-resolved synchrotron diffraction.     

Impact of Particulate Antigens, Such as Bacillus anthracis, on the Uniformity of Response across a Biosensor Flow Cell As Determined by GC-SPR

Biosensors are desired for the detection of a wide range of analytes in various scenarios, for example environmental monitoring for biological threats, from toxins to viruses and bacteria. Ideally a single sensor will be capable of simultaneous multianalyte detection. The varying nature, and in particular disparate size, of such a variety of analytes poses a significant challenge in the development of effective high-confidence instruments. Many existing biosensors employ functionalized flow cells in which spatially defined arrays of surface-immobilized recognition elements, such as antibodies, specifically capture their analyte of interest. To function optimally, arrays should provide equivalent responses for equivalent events across their active area. Experimental data obtained using a grating coupled surface plasmon resonance (GC-SPR) instrument, the BIAcore Flexchip, have revealed differences in response behaviors between proteinaceous and particulate analytes. In particular, the magnitude of responses seen with Bacillus anthracis spores appears to be influenced by shear and gravitational effects while those from soluble proteins are more uniform. We have explored this dependence to understand its fundamental impact on the successful implementation of multianalyte environmental biological detection systems.     

IR spectra of C2H5(+)-N2 isomers: evidence for dative chemical bonding in the isolated ethanediazonium ion

The potential energy surface (PES) of C(2)H(5)(+)-N(2) is characterized in detail by infrared photodissociation (IRPD) spectroscopy of mass-selected ions in a quadrupole tandem mass spectrometer and ab initio calculations at the MP2/6-311G(2df,2pd) level. The PES features three nonequivalent minima. Two local minima, 1-N(2)(H) and 1-N(2)(C), are adduct complexes with binding energies of D(0) = 18 and 12 kJ/mol, in which the N(2) ligand is weakly bonded by electrostatic forces to either the acidic proton or the electrophilic carbon atom of the nonclassical C(2)H(5)(+) ion (1), respectively. The global minimum 3 is the ethanediazonium ion, featuring a weak dative bond of D(0) = 38 kJ/mol. This interaction strength is sufficient to switch the C(2)H(5)(+) structure from nonclassical to classical. The 1-N(2)(C) isomer corresponds to the entrance channel complex for addition of N(2) to 1 yielding the product 3. This reaction involves a small barrier of 7 kJ/mol as a result of the rearrangement of the C(2)H(5)(+) ion. The partly rotationally resolved IRPD spectrum of C(2)H(5)(+)-N(2) recorded in the C-H stretch range is dominated by four bands assigned to 3 and one weak transition attributed to 1-N(2)(H). The abundance ratio of 1-N(2)(H) and 3 estimated from the IRPD spectrum as ～1% is consistent with the calculated free energy difference of 12 kJ/mol. As the ethanediazonium ion escaped previous mass spectrometric detection, the currently accepted value for the ethyl cation affinity of N(2) is revised from -ΔH(0) = 15.5 ± 1.5 to ～42 kJ/mol. The first experimental identification and characterization of 3 provides a sensitive probe of the electrophilic character and fluxionality of the ethyl cation. Comparison of 3 with related alkanediazonium ions reveals the drastic effect of the size of the alkyl chain on their chemical reactivity, which is relevant in the context of hydrocarbon plasma chemistry of planetary atmospheres and the interstellar medium, as well as alkylation reactions of (bio)organic molecules (e.g., carcinogenesis and mutagenesis of DNA material).     

A multifaceted approach to hydrogen storage

The widespread adoption of hydrogen as an energy carrier could bring significant benefits, but only if a number of currently intractable problems can be overcome. Not the least of these is the problem of storage, particularly when aimed at use onboard light-vehicles. The aim of this overview is to look in depth at a number of areas linked by the recently concluded HYDROGEN research network, representing an intentionally multi-faceted selection with the goal of advancing the field on a number of fronts simultaneously. For the general reader we provide a concise outline of the main approaches to storing hydrogen before moving on to detailed reviews of recent research in the solid chemical storage of hydrogen, and so provide an entry point for the interested reader on these diverse topics. The subjects covered include: the mechanisms of Ti catalysis in alanates; the kinetics of the borohydrides and the resulting limitations; novel transition metal catalysts for use with complex hydrides; less common borohydrides; protic-hydridic stores; metal ammines and novel approaches to nano-confined metal hydrides.