Enzyme Production by Solid Substrate Fermentation of <Emphasis Type="Italic">Pleurotus ostreatus</Emphasis> and <Emphasis Type="Italic">Trametes versicolor</Emphasis> on Tomato Pomace

A process of solid state fermentation (SSF) on tomato pomace was developed with the white-rot fungi Pleurotus ostreatus and Trametes versicolor, using sorghum stalks as support. Operative parameters (humidity, water activity, and size of substrate particles) guaranteeing a good colonization of tomato pomace by both fungi were defined and conditions for production at high titers of the industrially relevant enzymes laccase, xylanase and protease were identified. Significant laccase activity levels (up to 36 U g⁻¹ dry matter) were achieved without any optimization of culture conditions, neither by nutrient addition nor by O₂ enrichment. Furthermore, protease activity levels up to 34,000 U g⁻¹ dry matter were achieved, being higher than those reported for the fungi typically considered as the best protease producers such as Aspergillus strains. Moreover, as one of the most significant results of this study, analysis of P. ostreatus tomato SSF samples by zymogram revealed two bands with laccase activity which had not been detected so far.     

3-structures with torsion

We find conditions which ensure the integrability of the canonical 3-dimensional distribution spanned by the Reeb vector fields of an almost 3-contact manifold, showing by an explicit counterexample that the normality of the structures does not necessarily imply the integrability of . Then we focus on those almost 3-contact metric manifolds for which is integrable and we define an appropriate notion of almost 3-contact metric connection with torsion. The geometry of an almost 3-contact manifold with torsion is then studied and put in relation with the well-known HKT-geometry.     

Rigid chain ribbon‐like metallopolymers

A set of new copolymers is here reported in which the repeating units are connected each other through Cu(II) metal centers. The coordination link is based on the bis‐chelating properties of salicylaldiminate groups of two different monomers. Due to their chemical structure, the two monomers afford, respectively, flexible and rigid repeating units in the metallocopolymers constitution upon coordination to copper centers. All the copolymers were soluble and easily processable. As shown by XRD analysis, rigid units' rich copolymers adopt a ribbon‐like structure in solid state in which highly planar strands of polymer stack thanks to π?π interactions, similarly to the polymer composed exclusively by rigid units. This behavior can be justified assuming the existence of a partial block character in copolymer constitution where long sequences of rigid units are alternated to sequences of flexible units. This assumption is supported also by DSC and UV–Vis analysis. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2412–2421     

Dynamic nature of the ion wake in dusty plasmas

The dynamic nature of the ion wake formed downstream a dust particle immersed in a plasma with flowing ions has been investigated via Particle-in-Cell simulation. It is found that the wake oscillates in time and the motion is characterized by some dominant frequencies. By means of signal processing analysis, three harmonics are detected (two at low frequencies and one at high frequencies) and compared to the characteristic plasma frequencies given by the dispersion relations for ions and electrons. Good matching is found between the high frequency harmonic and the electron plasma frequency, and between the low frequency harmonics and the ion acoustic and ion plasma frequencies.     

How Big Is Too Big? Critical Shocks for Systemic Failure Cascades

External or internal shocks may lead to the collapse of a system consisting of many agents. If the shock hits only one agent initially and causes it to fail, this can induce a cascade of failures among neighboring agents. Several critical constellations determine whether this cascade affects the system in part or as a whole which, in the second case, leads to systemic risk. We investigate the critical parameters for such cascades in a simple model, where agents are characterized by an individual threshold θ _i determining their capacity to handle a load αθ _i with 1?α being their safety margin. If agents fail, they redistribute their load equally to K neighboring agents in a regular network. For three different threshold distributions P(θ), we derive analytical results for the size of the cascade, X(t), which is regarded as a measure of systemic risk, and the time when it stops. We focus on two different regimes, (i) EEE, an external extreme event where the size of the shock is of the order of the total capacity of the network, and (ii) RIE, a random internal event where the size of the shock is of the order of the capacity of an agent. We find that even for large extreme events that exceed the capacity of the network finite cascades are still possible, if a power-law threshold distribution is assumed. On the other hand, even small random fluctuations may lead to full cascades if critical conditions are met. Most importantly, we demonstrate that the size of the “big” shock is not the problem, as the systemic risk only varies slightly for changes in the number of initially failing agents, the safety margin and the threshold distribution, which further gives hints on how to reduce systemic risk.     

3-Quasi-Sasakian manifolds

We correct the results in section 6 of [B. Cappelletti Montano, A. De Nicola, G. Dileo, 3-Quasi-Sasakian manifolds, Ann. Global Anal. Geom. 33 (2008), 397–409], concerning the corrected energy of the Reeb distribution of a compact 3-quasi-Sasakian manifold. The results are slightly different than what was originally claimed and they are obtained by using results in [B. Cappelletti Montano, A. De Nicola, G. Dileo, The geometry of a 3-quasi-Sasakian manifold, Int. J. Math., to appear, arXiv:0801.1818], where the geometry of these manifolds is more deeply investigated. The online version of the original article can be found under doi:.     

Dilatazioni e varietà canoniche sulle varietà algebriche

Sunto è dato dagli ultimi due capoversi del n. 1.