The Influence of Mineral Ions on the Microbial Production and Molecular Weight of Hyaluronic Acid

This study aimed to evaluate the influence of the culture medium supplementation with mineral ions, focusing on the growth of Streptococcus zooepidemicus as well as on the production and average molecular weight (MW) of hyaluronic acid (HA). The ions were investigated in terms of individual absence from the totally supplemented medium (C+) or individual presence in the non-supplemented medium (C−), where C+ and C− were used as controls. Differences between the effects were analyzed using the Tukey's test at p < 0.05. The adopted criteria considered required the ions, whose individual absence attained at 80% or less of the C+ and their individual presence was 20% or more than the C−. The supplementation was either inhibitory or acted in synergy with other ions, when the individual absence or presence was 20% higher than C+ or 20% lower than C−, respectively. Results showed that the effects of C+ or C− were equal for both the production of HA and its yield from glucose. However, C+ showed to be beneficial to cell growth while the individual absence of Na⁺ was beneficial to the production of HA. The highest MW of HA (7.4 × 10⁷ Da) was observed in the individual presence of Na⁺ in spite of the lowest HA concentration (0.65 g.L⁻¹). These results suggest that the quality of HA can be modulated through the mineral ion supplementation.     

Fullerene Derivatives Functionalized with Diethylamino‐Substituted Conjugated Oligomers: Synthesis and Photoinduced Electron Transfer

Diethylamino‐substituted oligophenylenevinylene (OPV) building blocks have been prepared and used for the synthesis of two [60]fullerene–OPV dyads, F‐D1 and F‐D2 , which exhibit different conjugation length of the OPV fragments. The electrochemical properties of these acceptor–donor dyads have been studied by cyclic voltammetry. The first reduction is always assigned to the fullerene moiety and the first oxidation centered on the diethylaniline groups of the OPV rods, thus making these systems suitable candidates for photoinduced electron transfer. Both the OPV and the fullerene‐centered fluorescence bands are quenched in toluene and benzonitrile, which suggests the occurrence of photoinduced electron transfer from the amino‐substituted OPVs to the carbon sphere in the dyads in both solvents. By means of bimolecular quenching experiments, transient absorption spectral fingerprints of the radical cationic species are detected in the visible (670 nm) and near‐IR (1300–1500 nm) regions, along with the much weaker fullerene anion band at λ_max=1030 nm. Definitive evidence for photoinduced electron transfer in F‐D1 and F‐D2 comes from transient absorption measurements. A charge‐separated state is formed within 100 ps and decays in less than 5 ns.     

Finiteness conditions on subgroups of profinite p-Poincaré duality groups

For a prime number p let G be a profinite p-PD _n group with a closed normal subgroup N such that G/N is a profinite p-PD _m group and that H _i (V, $ \mathbb{F} $ \mathbb{F} _p ) is finite for every open subgroup V of N and all i ≤ [n/2]. Generalising [12, Thm. 3.7.4] we show that m ≤ n and N is a profinite p-PD _{n − m} group. In case that G is a pro-p PD _n group of Euler characteristic 0 with a closed normal subgroup N of type FP _{[n−1 / 2]} such that G/N is soluble-by-finite pro-p group of finite rank, we show that N is a pro-p PD _{n − m} group, where m = vcd _p (G/N). As a corollary we obtain that a pro-p PD ₃ group with infinite abelianization is either soluble or contains a free nonprocyclic pro-p subgroup.     

Purity evaluation and influence of carbon nanotube on carbon nanotube/graphite thermal stability

High resolution thermogravimetry has been used to evaluate the carbonaceous content in a commercial sample of single-walled carbon nanotube (SWNT). The content of SWNTs in the sample was found to be at least 77 mass% which was supported by images obtained with scanning and transmission electron microscopies (SEM and TEM). Furthermore, the influence of SWNT addition on the thermal stability of graphite in mixtures of SWNT/graphite at different proportions was investigated. The graphite stability decreased with the increased of SWNT content in the overall range of composition. This behavior could be due to the close contact between these carbonaceous species as determined by SEM analysis.     

Free and bound aroma compounds characterization by GC-MS of Negroamaro wine as affected by soil management

Negroamaro is an autochthonous wine grape variety of Southern Italy, which is becoming very important for the Italian wine market. The wine aroma is primary affected by the chemical composition of grapes, which can be influenced also by agronomic practices such as soil management. In this study, the free and bound aroma characterization was performed by gas chromatography-mass spectrometry analyses, and the influence of two soil managements (cover cropping and soil tillage) was evaluated. A total of 40 volatile compounds were observed in the wine samples. Alcohols (55.7?mg/L), fatty acids (7.0?mg/L) and esters (6.6?mg/L) were found as the main classes in Negroamaro wine. The results showed that the aroma composition of Negroamaro wine was positively affected by soil tillage probably because of the higher water stress (ψ(s) ) recorded in the vines from this treatment. Indeed, among the free volatile compounds, higher contents of esters, carboxylic acids, alcohols, phenolics and acetamides together with lower contents of sulfurs compounds were found in soil tillage wine. Conversely, no difference was observed in glycoside volatile compounds. Copyright ? 2012 John Wiley & Sons, Ltd.     

Effects of Impregnated Amidophosphonate Ligand Concentration on the Uranium Extraction Behavior of Mesoporous Silica

A series of solid-phase uranium extractants were prepared by post-synthesis impregnation of a mesoporous silica support previously functionalized with octyl chains by direct silanization. Five materials were synthesized with 0, 0.2, 0.3, 0.4 and 0.5 mmol of the amidophosphonate ligand DEHCEBP per gram of functionalized solid, and the effect of the ligand concentration on the uranium extraction efficiency and selectivity of the materials was investigated. Nitrogen adsorption–desorption data show that with increasing ligand loadings, the specific surface area and average pore volume decrease as the amidophosphonate ligand fills first the micropores and then the mesopores of the support. Acidic uranium solutions with a high sulfate content were used to replicate the conditions in ore treatment leaching solutions. Considering the extraction kinetics, the equilibration time was found to increase with the ligand concentration, which can be explained by the clogging of micropores and the multilayer arrangement of the DEHCEBP molecules in the materials with their highest ligand contents. The fact that the equilibrium ligand/uranium ratio is about 2 mol/mol regardless of the ligand concentration in the material suggests that all the ligand molecules remain accessible for extraction. The maximum uranium extraction capacities ranged from 30 mg∙g⁻¹ at 0.2 mmol∙g⁻¹ DEHCEBP to 54 mg∙g⁻¹ in the material with 0.5 mmol∙g⁻¹ DEHCEBP. These materials could therefore potentially be used as solid-phase uranium extractants in acidic solutions with high sulfate concentrations.     

β-Alkylation through Dehydrogenative Coupling of Primary Alcohols and Secondary Alcohols Catalyzed by Thioether-Functionalized N-Heterocyclic Carbene Ruthenium Complexes

A catalytic system for the direct β-alkylation of secondary alcohol with primary alcohol has been investigated. In this work, a series of cationic Ru(II)(η⁶-p-cymene) complexes with thioether-functionalized N-heterocyclic carbene ligands (imidazole-based 1 a – l and benzimidazole-based 2 a – e ) have been successfully synthesized and evaluated as catalysts. This investigation shows that modifications in the ligand moiety (thioether group and/or NHC core) have a strong effect on both selectivity and reactivity. Imidazole-based complex 1 c , with only 1 mol % of catalyst loading, displayed the best catalytic activity as well as the highest selectivity for the β-alcohol up to 98 : 2 for this tandem borrowing hydrogen/aldol methodology. Applied to a wide range of substrates, β-alkylated secondary alcohols have been obtained in moderate yields, but generally with complete conversion and very high selectivity.