Co-Culture of Microalgae, Cyanobacteria, and Macromycetes for Exopolysaccharides Production: Process Preliminary Optimization and Partial Characterization

In this study, the biomass and exopolysaccharides (EPS) production in co-cultures of microalgae/cyanobacteria and macromycetes was evaluated as a technology for producing new polysaccharides for medical and/or industrial application. Based on biomass and EPS productivity of monocultures, two algae and two fungi were selected and cultured in different co-culture arrangements. The hydrosoluble EPS fractions from mono- and co-cultures were characterized by 13C NMR spectroscopy and gas chromatography coupled to mass spectrometry and compared. It was found that co-cultures resulted in the production of an EPS different from those produced by monocultures, showing fungal predominance with microalgal/cyanobacterial traces. Co-cultures conditions were screened (temperature, agitation speed, fungal and microalgae inoculation rate, initial pH, illumination rate, and glucose concentration) in order to achieve maximum biomass and EPS production, resulting in an increase of 33 and 61% in exopolysaccharides and biomass productions, respectively (patent pending).     

Influence of Molar Mass and Concentration on the Thermogelation of Methylcelluloses

In this study, thermogelation of methylcelluloses is investigated in relation to the molar mass and concentration in aqueous medium. A large hysteresis between heating and cooling ramps was observed whatever the conditions. The heating process in particular was studied to analyze the two steps of gelation using rheometry. At low temperature, in the sol state, viscosity depends on the concentration and molar mass. Over 30°C a gel-like behavior was observed including two steps (the second step is a strong gel with phase separation) having storage moduli that are nearly independent of polymer molar mass but are directly related to polymer concentration.     

Synthesis and photophysical evaluation of meso-phenyl-1,4-dihydropyridineand pyridine-porphyrin hybrids

Chemistry of Heterocyclic Compounds - In the present work, we have synthesized new molecular hybrids consisting of porphyrin ring system connected at the meso positions with phenyl groups and/or,...     

ESI-MS differential fragmentation of positional isomers of sulfated oligosaccharides derived from carrageenans and agarans

We have prepared a number of isomeric red seaweed galactan-derivative sulfated oligosaccharides to determine whether there were diagnostic differences among the isomeric mass spectra obtained using ESI CID MS/MS (triple quadrupole instrument). Fragmentation of the single or multicharged molecular ions from di-, tetra-, and hexasaccharides indicated that the relative positioning of the sulfate groups and type of monosaccharide unit affect the rate of cleavage of the glycosidic bonds. We also performed a comparative [M-Na]⁻ fragmentation study of positional isomers of sulfated disaccharides that present all four monosulfation possibilities on the galactopyranosidic ring. In this case, negative-ion ESI CID MS/MS approach gave diagnostic product ions from cross-ring cleavages along with the same main B₁ ion (from sulfated Gal_p), at m/z 241, for all isomers. The isomeric disaccharides were also submitted to increased spray energy conditions inducing in-source fragmentation; preformed B₁ ions were then fragmented to give similar product ions as those found in [M-Na]⁻ analysis. Evaluation of the relative abundances mainly for cross-ring fragment ions at m/z 138, 139, 151, 153 allowed clear distinction among the members of the disaccharide series. The different ratios for m/z 151/153 ions were consistent with the predominance of m/z 153 being related to the cases when the bond involved in the cleavage process links a sulfated carbon. A quadrupole ion trap instrument (MSⁿ analysis) was also utilized to compare the results obtained with the triple quadrupole instrument.     

A mathematical model of the arterial system

Summary A mathematical model of the major arteries of sistemic circulation in the man is proposed. According to the model, flow is regarded as a one-dimensional whole. The numerical solution is obtained with the method of characteristics, applied to the case of an elastic, incompressible vessel wall. The model is applied to study the behaviour of six different cases. The results show that the model provide an appropriate representation of the behaviour of the major arteries in the sistemic circulation.

---

Sommario Viene proposto un modello matematico per lo studio del comportamento meccanico del sistema circolatorio arterioso. Il modello utilizza lo schema di processo unidimensionale normalmente impiegato in meccanica dei fluidi; la soluzione è ottenuta con il metodo delle caratteristiche per il caso di tubi con comportamento elastico. Il modello à stato applicato a sei diverse situazioni. I risultati ottenuti mostrano la buona validità del modello matematico proposto.

---

---

Research supported by C.N.R.     

Flow profiles in rectangular channels with gradually varying width

Summary We examine here the steady flow with constant discharge in an open channel of uniform bottom slope and with rectangular cross-section of uniformly increasing or decreasing width.The discussion of the dynamic differential equation of the gradually varied flow, using the theory of the singular point, permits us to describe the characteristics of the various flow profiles and also of the corresponding energy lines.This work was presented at the IX Convegno di Idraulica e Costruzioni Idrauliche, Trieste, May 1965.     

1,4-Dihydropyridine/BF3OEt2 for the reduction of imines: Influences of the amount of added BF3OEt2 and the substitution at N-1 and C-4 of the dihydropyridine ring

We have evaluated four 1,4-dihydropyridines (DHPs 1a, 1b, 1c and 1d) as reducing agents, which presented free (hydrogenated) or phenyl-substituted N-1 and C-4 positions of the DHP ring. Reactions combining each of the DHP and different amounts of BF₃OEt₂ were evaluated for the reduction of imine 2a (N-benzylideneaniline). DHP simultaneously substituted at N-1 and C-4 (1a), and DHP substituted at C-4 (1b) gave lower yields for reduction of 2a in comparison with DHPs 1c and 1d (both unsubstituted at the C-4 position). By evaluating the amount of added BF₃OEt₂ to the reaction mixture, we have found that DHP 1c (substituted at N-1) provided its best yield for amine 3a (82%) when associated with stoichiometric amounts BF₃OEt₂, while DHP 1d (N-1- and C-4-unsubstituted derivative) was more effective (90% yield) with catalytic quantities of the Lewis acid. The reaction system using DHP 1c under stoichiometric BF₃OEt₂ could also be successfully applied with additional imine examples and under reductive amination conditions.     

Thermal stability and degradation of meso-tetraphenylporphyrins bearing nitrogen-containing substituents

Journal of Thermal Analysis and Calorimetry - Porphyrins have exquisite photophysical and electronic properties that enable their use in photodynamic therapy. Even though the thermodynamic behavior...     

Selective polarity- and adsorption-guided extraction/purification ofAnnona sp. Polar acetogenins and biological assay against agricultural pests

Annonaceae acetogenins (AG) comprise a family of natural chemical modifications of long-chain fatty acids (C₃₅_₃₇) bearing one to several hydroxyls (less often oxo), middle-chain tetrahydrofuran rings, and a γ-lactonized, α/β-unsaturated carboxyl group. Acetogenins’ strong biological activity as larvicides, pesticides, and antitumorals is dependent on these structural variations. The hydroxylation degree is particularly important for these etfects. Seeds, albeit rich in fats (mostly triacylglycerols, [TAG]), are a nonpredatory source of these drugs as compared to other botanical parts such as roots and stems. Conventional lipid extractions lead to quantitative lipid recovery and then the unfavorable natural ratio of TAG:AG in the range >90:<0.1 These extracts thus require, for instance, partitions and extensive sílica gel column chromatographic steps, in order to enrich or purify the AG fraction(s). Great operational difficulties result from the similar polarity and mol. wt. range of TAG and AG when carrying out these purification steps. An alternative fast two-step procedure to obtain polar acetogenin (pAG)-enriched preparations was developed. The extraction procedure forAnnona spp. seeds pAG was carried out with acetonitrile (Eβ = 0.65; log P = - 0.33) as a polar organo-solvent, followed by the adsorption of the solvent-free extract on activated charcoal, then washed with hexane and/or chloroform (Eβ = 0.0 and 0.40: log P = 3.5 and 2.0) for most of the contaminating TAG removal, and then with acetone (Eβ = 0.56; log P = - 0.23) to the desorption of an enrichedpAG fraction. An alternative procedure for pAG extraction was supercritical fluid extraction (SFE) at moderate thermopressurization conditions (65-82βC; 120-130 atm) using CO2, with 10% acetonitrile as the polarity modifier. The pAG fractions’ bioactivity was evaluated with the brine-shrimp test (BST), and for feed deterrance, growth inhibition, and lethality against the high-impact agricultural pestsAnticarsia gemmatalis andPseudaletia sequax caterpillars feeding on soya or grass leaves sprayed with a 10% alcohol-stabilized emulsion of pAG.