Synthesis of crosslinked nanostructured saccharidic vinyl copolymers and their functionalization

Saccharidic monomers and a macromonomer were synthesized and copolymerized in the presence of divinylbenzene (DVB) as crosslinker in conditions of separation of phases to give hydrophilic nanostructured sugar-based vinyl copolymers. Appropriate model molecules such as N-benzyl-d-gluconamide for the saccharidic copolymers and 4-(4-chlorobutoxy)benzaldehyde and (E)-4-(4-chloro-2-butenyloxy)benzaldehyde for electrophilic reagents prefiguring possible copper amine oxidase inhibitors allowed identification of conditions for useful monofunctionalizations mainly at the position 2 of the saccharidic units. The examined samples of the nanostructured copolymers from one of the monomers proved to be stable enough to tolerate the functionalization reactions without loss of morphology.     

2-substituted benzofuran fragment ion formation in the electron ionization mass spectra of 6-alkyl- and 6-aryldibenzo(d,f)(1,3)dioxepine derivatives. 1. Spirocyclization of the molecular ions in the gas phase

The formation of 2-substituted benzo[b]furan ions in the electron ionization (EI) mass spectra of a series of 6-alkyl- and 6-aryldibenzo(d,f)(1,3)dioxepines has been studied by means of exact mass measurements and multiple-stage mass spectrometry conditions using an ion trap mass spectrometer. The proposed mechanism of formation of benzo[b]furan ions requires the formation of a spirocyclic cyclohexadienone system, which undergoes elimination of a cyclopentadienone molecule. A parallel with the chemical conversion of arylmethyl-substituted dibenzo(d,f)(1,3)dioxepines into an analogous spirocyclic system was also underlined.     

Study on the Performance of Three Different Capillary Gas Chromatographic Analyses in the Evaluation of Milk Fat Purity

The adulteration of milk fat with foreign fat has been and still is a major concern in the dairy industry. Milk fat purity is currently evaluated by triglyceride analysis by using the Official EU method. The detection limit of the various vegetable and animal fats ranges between 4 and 6%. This research was carried out to verify whether it is possible to decrease the detection limits of beef tallow, which is the most widely used adulterating animal fat. For this purpose, determinations of diglycerides and 3,5-cholestadiene, together with the Official EU method, were applied both to several samples of pure milk fat and to mixtures of milk fat with different percentages of beef tallow. The best results were obtained combining the data deriving from the three determinations by multivariate statistical techniques; in particular, the statistical model obtained by the UNEQ technique seems to be able to decrease the detection limit of beef tallow from 5.2 to 2%. The diglyceride and 3,5-cholestadiene evaluation, combined with the Official EU method for triglycerides, can be usefully applied both to detect small additions of beef tallow and to demonstrate the adulteration of milk fat samples showing results close to the detection limit of the official method.     

Purification and Applications of a Lectin from the Mushroom Gymnopilus spectabilis

A lectin was isolated from fruiting bodies of the mushroom Gymnopilus spectabilis (GSL) by ionic exchange chromatography. The lectin agglutinates mouse red cells exhibiting broad specificity towards several monosaccharides including the N-acetylneuraminic acid. Agglutination was also inhibited by the glycoproteins: fetuin, lactoferrin, and recombinant erythropoietin. GSL is a glycoprotein possessing 16 % of carbohydrates; the SDS-PAGE showed two bands with molecular mass of 52.1 and 64.4 kDa. Isoelectric focusing displayed microheterogeneity, with two bands at pIs 5.1 and 5.3. The lectin was stable between pH 2 and pH 8 while at pH 10, the agglutination decayed to 50 % of initial activity. Incubation at 40 and 80 °C led to 50 and 100 % loss in activity of the lectin, respectively. Synthesized GSL-Sepharose interacts with serum pregnant mare gonadotropin, and at least two subpopulations of this glycoprotein were separated. There was no interaction between transferrin and soluble GSL while a partial recognition was achieved with GSL-Sepharose. The terminal sialic acid seems to play an active role in modifying the interaction with GSL, depending if the lectin is in a soluble or immobilized form. The purified lectin inhibited in vitro the growth of Staphylococcus aureus and Aspergillus niger.     

Gold chloride cluster ions generated by vacuum laser ablation

In this work, a simple way for study the possibility of formation a vapor cluster species of tetrachloroauric acid (HAuCl₄), using the laser ablation in the absence of a buffer or reactive atmosphere, and without a postablation supersonic expansion on a commercial matrix assisted laser desorption/ionization time-of-flight mass spectrometer, is reported. Tetrachloroauric acid is known as precursor for the synthesis of gold nanostructures and the complex salts; therefore it is an important task to discover and quantify the species arising from HAuCl₄, in order to understand their role in the gold assisted reactions. Mass spectrum of HAuCl₄ in a reflector negative-ion mode contains the hydrated mono- and dinuclear gold clusters in the m/z range 286–436, and gold chloride clusters in the m/z range 447–795. In the first part of spectrum, m/z range 286–436, the hydrated gold cluster species of type Au _n ^? (H₂O)_m (n?=?1–2; m?=?1, 2, 5, 7, 8) and [Au_n(OH)_k]^?(H₂O)_m (n?=?1–2; k?=?1–2; m?=?1, 4–8) were found. Besides that, there are gold chloride clusters with general formula [AuH_r(HCl)₂]^?(H₂O)_m (m?=?1–5; 8–9; r?=?0–2) in this part of spectrum. In the second part of spectrum, the m/z range 447–795, only gold chloride clusters were obtained. Their general formulae can be written as [AuCl_t(HCl)_v]^?(H₂O)_m (t?=?1–4; v?=?5–8; m?=?2–4, 6–8) and [Au_n(HCl)_v]^?(H₂O)_m (n?=?1–2, v?=?4–5, m?=?1–2, 5, 7). The analysis of concentration effects on the LDI mass spectra of gold clusters reveals that the relative intensities of signals for the mono- and dinuclear Au clusters increase with decreasing the concentration of water HAuCl₄ solutions.     

Effects of localised and global convection on thermal explosion in a parallel-plate geometry

During an exothermic reaction in a fluid, convection may ensue on a local scale and then develop to the scale of the entire vessel. In this work, we study the effects of both localised and global convection on thermal explosions occurring between parallel plates. Analytical relations are derived for the various transitions in regimes of convective and thermal behaviours. We show that these relations agree well with previous numerical work and with new simulations in the present investigation. We also determine analytically the time for onset of convection, as well as the temperature increase at that time, for stable and explosive systems. The effects of the Prandtl number of the fluid on the transitions between regimes are noted.     

Isomorfismi tra le strutture subnormali dei gruppi

Summary In this paper order-isomorphisms between subnormal structures of subsoluble groups are considered, and the images of generalized nilpotent groups in such isomorphisms are studied. A result of Pazderski about the Fitting subgroup of finite soluble groups is also extended to the upper Baer series of subsoluble groups, and an extension to infinite groups of a theorem of Heineken about isomorphisms between lattices of subnormal subgroups of finite groups is given.

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Lavoro eseguito nell'ambito del G.N.S.A.G.A. del C.N.R.     

Some functional inequalities for complete elliptic integrals

We establish some monotonicity results and inequalities involving elliptic integrals of the first and the second kind. Work sponsored by the Ministero dell’Università e della Ricerca Scientifica e Tecnologica of Italy.     

Comparison of microbial activity in some Brazilian soils by microcalorimetric and respirometric methods

The microbial activity in a Rhodic eutrudox (R), a Typic eutrudox (V) and a Quartzipsamment (Q) was monitored by respirometric and calorimetric methods. CO₂ evolution was monitored for 98 days by titrimetry and conductimetry for control amended samples (A) with 25% of cattle manure (E), municipal refuse compost (L), earthworm casts (H) or 1.25 kg ha⁻¹ of trifluralin (T). Average values of all treatments through respiration at the end of the incubation period were 5.24±0.34, 6.13±0.31 and 6.50±0.33, in mg CO₂ g⁻¹ soil, for R, V and Q, respectively, by titrimetry and 8.89±0.44, 10.41±0.54 and 10.41±0.52, in mg CO₂ g⁻¹ soil, for R, V and Q, respectively, for conductimetry. Excellent correlation (r=1.00) between titrimetry and conductimetry was observed. The decreasing order for respiration was E, H, L and T. After each incubation time, the conductimetric values were higher than those for titrimetry, for all treatments of these Brazilian soils. Average values of the exothermic thermal effect were: 0.58±0.02, 0.60±0.02 and 0.67±0.01 kJ g⁻¹ soil, for R, V and Q, respectively, for 103 days. A significant correlation coefficient of 0.91 and P<0.0001 between calorimetric and respirometric values over 98 days was observed. Based on the obtained calorimetric results, it can be proposed that this technique should be as a useful analytical method for determining the microbial activity in soils.     

On automorphisms fixing non-normal subgroups of groups

This work was carried out when the last named author visited the Department of Mathematics of the University of Napoli Federico II in March 1994. He is very grateful for the hospitality he enjoyed and for the support by the C.N.R.