Solid-State Treatment of Castor Cake Employing the Enzymatic Cocktail Produced from <Emphasis Type="Italic">Pleurotus djamor</Emphasis> Fungi

In this work, the enzymatic cocktail produced by Pleurotus djamor fungi extracted at pH of 4.8 and 5.3 was employed for castor cake solid-state treatment. Proximal, X-ray powder diffraction and scanning electron microscopy analysis of the pristine castor cake were carried out. First, Pleurotus djamor stain was inoculated in castor cake for the enzymatic production and the enzymatic activity was determined. The maximum enzymatic activity was identified at days 14 (65.9 UI/gss) and 11 (140.3 UI/gss) for the enzymatic cocktail obtained at pH 5.3 and 4.8, respectively. Then, the enzymatic cocktail obtained at the highest enzymatic activity days was employed directly over castor cake. Lignin was degraded throughout incubation time achieving a 47 and 45% decrease for the cocktail produced at pH 4.8 and 5.3, correspondingly. These results were corroborated by the SEM and XRD analysis where a higher porosity and xylan degradation were perceived throughout the enzymatic treatment.     

High‐Pressure Synthesis of a Nitrogen‐Rich Inclusion Compound ReN8⋅x N2 with Conjugated Polymeric Nitrogen Chains

A nitrogen‐rich compound, ReN₈?x N₂, was synthesized by a direct reaction between rhenium and nitrogen at high pressure and high temperature in a laser‐heated diamond anvil cell. Single‐crystal X‐ray diffraction revealed that the crystal structure, which is based on the ReN₈ framework, has rectangular‐shaped channels that accommodate nitrogen molecules. Thus, despite a very high synthesis pressure, exceeding 100 GPa, ReN₈?x N₂ is an inclusion compound. The amount of trapped nitrogen (x) depends on the synthesis conditions. The polydiazenediyl chains [?N=N?]_∞ that constitute the framework have not been previously observed in any compound. Ab initio calculations on ReN₈?x N₂ provide strong support for the experimental results and conclusions.     

Post‐Synthetic Ligand Exchange in Zirconium‐Based Metal–Organic Frameworks: Beware of The Defects!

Post‐synthetic ligand exchange in the prototypical zirconium‐based metal–organic framework (MOF) UiO‐66 was investigated by in situ solution ¹H NMR spectroscopy. Samples of UiO‐66 having different degrees of defectivity were exchanged using solutions of several terephthalic acid analogues in a range of conditions. Linker exchange only occurred in defect‐free UiO‐66, whereas monocarboxylates grafted at defect sites were found to be preferentially exchanged with respect to terephthalic acid over the whole range of conditions investigated. A 1:1 exchange ratio between the terephthalic acid analogue and modulator was observed, providing evidence that the defects had missing‐cluster nature. Ex situ characterisation of the MOF powders after exchange corroborated these findings and showed that the physical‐chemical properties of the MOF depend on whether the functionalisation occurs at defective sites or on the framework.     

Asymmetric synthesis and structure-activity studies of the fungal metabolites colletorin A,colletochlorin A and their halogenates analogues

The first asymmetric total synthesis of both enantiomers of the natural products colletorin A and colletochlorin A is presented. The proposed methodology is based on the coupling reaction between highly substituted aromatic Gilman cuprates and optically active allyl bromides, in turn obtained by Sharpless asymmetric dihydroxylation. The latter ensured a high degree of regio- and stereocontrol in the enantioselective step of the synthesis. The same synthetic strategy has been also applied for the preparation of differently halogenated synthetic analogues of colletochlorin A in high enantiomeric purity. The enantioselective synthesis of colletorin A and colletochlorin A allows to reliably assign their absolute configuration. Preliminary assessment of their herbicidal and insecticidal properties evidence the possibility to modulate the bioactivity of these compounds, highlighting its dependence on both the absolute stereochemistry and the halogen nature.     

Simplicial Homotopical Algebra and Satellites

We study here a notion of simplicial satellites, as a first step towards a characterisation of simplicial derived functors, a problem unsolved since the latter were introduced.The problem comes from the fact that, in contrast with the abelian case, simplicial derived functors do not produce by themselves an exact sequence. Our solution consists in extending them to commutative k-cubes, for all k, forming thus an exact system of functors universal within the connected ones; or, in other words, a system of simplicial satellites. The tool we develop here for this extension is the homotopy kernel of a commutative k-dimensional cubic diagram, generalising the homotopy kernel of a map; its 2-dimensional version has already been proved essential in other homotopical topics.     

Smooth Stable Planes

This paper deals with smooth stable planes which generalize the notion of differentiable (affine or projective) planes [7]. It is intended to be the first one of a series of papers on smooth incidence geometry based on the Habilitationsschrift of the author. It contains the basic definitions and results which are needed to build up a foundation for a systematic study of smooth planes. We define smooth stable planes, and we prove that point rows and line pencils are closed submanifolds of the point set and line set, respectively (Theorem (1.6)). Moreover, the flag space is a closed submanifold of the product manifold $P\times {\cal L}$ (Theorem (1.14)), and the smooth structure on the set P of points and on the set ${\cal L}$ of lines is uniquely determined by the smooth structure of one single line pencil. In the second section it is shown that for any point p \te P the tangent space T_pP carries the structure of a locally compact affine translation plane ${\cal A}_p$ , see Theorem (2.5). Dually, we prove in Section 3 that for any line $L \in {\cal L}$ the tangent space ${\rm T}_L{\cal L}$ together with the set ${\cal \rm S}_L=\lbrace {\rm T}_{L}{\cal L}_p\mid p \in L\rbrace$ gives rise to some shear plane. It turned out that the translation planes ${\cal A}_p$ are one of the most important tools in the investigation of smooth incidence geometries. The linearization theorems (3.9), (3.11), and (4.4) can be viewed as the main results of this paper. In the closing section we investigate some homogeneity properties of smooth projective planes.     

On 2-very ample divisors of genus ⩽8 on algebraic surfaces

In this paper we study the k-very ampleness of certain classes of divisors of genus 8 on rational and ruled surfaces appearing in the papers [La] of A. Lenteri and [An] of M. Andreatta.Research carried out under the EC HCM project AGE (Algebraic Geometry in Europe), contract number ERBCHRXCT 940557.     

On the hyperbolic limit points of groups acting on hyperbolic spaces

We study the hyperbolic limit points of a groupG acting on a hyperbolic metric space, and consider the question of whether any attractive limit point corresponds to a unique repulsive limit point. In the special case whereG is a (non-elementary) finitely generated hyperbolic group acting on its Cayley graph, the answer is affirmative, and the resulting mapg ⁺↦g ⁻, is discontinuous everywhere on the hyperbolic boundary. We also provide a direct, combinatorial proof in the special case whereG is a (non-abelian) free group of finite type, by characterizing algebraically the hyperbolic ends ofG. Partially supported by a grant from M.U.R.S.T., Italy.