On solutions of differential inclusions in homogeneous spaces of functions

In this paper we study the solvability of some classes of differential inclusions with multivalued linear operators in homogeneous spaces of functions. These spaces include a large number of functional spaces like periodic functions and Bohr and Stepanov almost periodic functions. As an application, we consider some existence results for feedback control systems governed by degenerate differential equations of Sobolev type in a Banach space.     

Peculiar behavior of polysaccharide/borax hydrogel tablets: a dynamomechanical characterization

The peculiar unidirectional elongation observed during swelling of tablets prepared with scleroglucan (Sclg) and borax was compared with that of other synthetic and natural polymers capable of physical/chemical interactions with borate ions. A dynamomechanical characterization of “squared” Sclg/borax tablets was carried out to study the differences detectable on the two sides of the matrix corresponding to the two directions, respectively, the parallel and perpendicular one with respect to the applied compression force. Different compression forces were used and, in some cases, a second compression was applied on the tablets along a direction perpendicular to the first one. Birefringence experiments were carried out on the swelled tablets along the two directions. Obtained results allow correlating the anisotropic swelling behavior with the detected dynamomechanical and optical properties of the Sclg/borax system. Among the various tested polymers, only guar gum and, to a lesser extent, locust bean gum, showed an anisotropic elongation during swelling.     

A versatile modular computational tool for complex optoelectronic integrated circuits simulation

A novel graphical computational tool to simulate a wide variety of complex optoelectronic integrated circuits is presented. Based upon a modular approach, this tool reduces the optical circuit into a sequence of interconnected building blocks, each one performing a specific data-flow oriented function onto an input optical stream. The modularity and the flow-based interconnectivity makes this simulator flexible and powerful, yet intuitive. Its execution speed is evaluated using a sophisticated amplifier simulation module that is compared against its replica written in a text-based programming language. More than four times outperformance is reported. The simulator capabilities are further demonstrated through an application example in the field of optical data processing: the analysis of a semiconductor optical amplifier-based Mach–Zehnder interferometer operated as wavelength converter for signals modulated at 40 Gb/s. This simulator represents an attractive alternative to more traditional approaches.     

NH‐Heterocyclic Aryliodonium Salts and their Selective Conversion into N1‐Aryl‐5‐iodoimidazoles

The synthesis of N‐arylimidazoles substituted at the sterically encumbered 5‐position is a challenge for modern synthetic approaches. A new family of imidazolyl aryliodonium salts is reported, which serve as a stepping stone on the way to selective formation of N1‐aryl‐5‐iodoimidazoles. Iodine acts as a “universal” placeholder poised for replacement by aryl substituents. These new λ³‐iodanes are produced by treating the NH‐imidazole with ArI(OAc)₂, and are converted to N1‐aryl‐5‐iodoimidazoles by a selective copper‐catalyzed aryl migration. The method tolerates a variety of aryl fragments and is also applicable to substituted imidazoles.     

Human capital estimation in higher education

The concept of human capital (HC) could be defined, from an economical viewpoint, as a stock variable representing the capacity of an individual to produce a sustained flow of income due to its investment in (higher) education and work experience. This paper focuses on the empirical estimation of the graduates’ latent variable HC, composed of two principal dimensions, Educational HC and Work Experience HC, within a realistic structural model, allowing causal relationship among endogenous and exogenous indicators, taking into account possible effects of external covariates. New administrative archives and a novel methodological approach are used. The methodology is applied to estimate HC of graduates in several universities of the Milan area in the early stages of their working career. The empirical results confirm the structure of the Italian job market, where investment in HC through higher education plays only a marginal role for explaining the economic performance.     

The Reaction Pathway of Cellulose Pyrolysis to a Multifunctional Chiral Building Block: The Role of Water Unveiled by a DFT Computational Investigation

LAC (hydroxylactone (1R,5S)‐1‐hydroxy‐3,6‐dioxabicyclo[3.2.1]octan‐2‐one) is one of the most interesting products of the pyrolysis of cellulose and represents a useful chiral building block in organic synthesis. A computational investigation at the DFT level on the mechanism of formation of LAC shows that this species can be obtained following two reaction paths, path A and path B , starting from a well‐known pyrolysis product (ascopyrone P). A series of internal rearrangements involving in all cases a proton transfer leads directly to LAC ( path B ). An alternative path ( path A ) can be also followed. From this path, via a “gate” connecting the two reaction channels, it is possible to reach path B and form LAC. In both cases, the rate‐determining step of the process is the initial keto‐enol isomerization. We found that water, which is present in the reaction mixture, “catalyzes” the reaction by assisting the proton transfers present in all the steps of the process. In particular, water lowers the barrier of the rate‐determining step that becomes 40.9 kcal mol^?1 (79.4 kcal mol^?1 in the absence of water). The corresponding computed rate constant is 4.3×10 s^?1 at 500 °C, a value which is consistent with the presence of LAC in the absence of metal catalysts. The results of this study on the non‐catalyzed process underpin the important role played by water in the formation of pyrolysis products of cellulose where proton transfer is a key mechanistic step.     

Periodic Solutions of the Burgers-Hopf Equation with Small Parameter and its Cellular Neural Network Model

This paper deals with the periodic solutions of the Cauchy problem to the Burgers-Hopf equation containing small viscosity term. We propose at first an explicit formula for the exact solution of the Cauchy problem and then we give an approximate formula. We use CNN approach for constructing the approximate solution and we find precise estimates of the remainder term. This work was supported by the NATO Grant ICS.NR.CLG 981757.     

Chemoenzymatic and yeast-catalysed synthesis of diastereomeric ethyl γ-phenyl and γ-(n-pyridyl)paraconates

The synthesis of γ-phenyl and γ-(n-pyridyl)paraconates was accomplished by chemical reduction of their respective ketodiester precursors followed by cyclisation of the resulting hydroxy diester intermediates. The cis- and trans-lactones thus obtained were separated and separately subjected to enzymatic hydrolysis with HLAP. The cis-lactonic esters had enantiomeric excesses ranging from 94% to 99%, while for the trans-isomers the ee’s ranged from 80% to 93%. The same ketodiester precursors were subjected to reduction with a series of yeasts. The absolute configuration of trans-(−)-2-pyridyl paraconic acid was assigned by means of X-ray analysis of its hydrobromide salt, while the absolute configurations of the other lactones were determined via analysis of their respective CD curves.     

Premicellar accelerated decarboxylation of 6-nitrobenzisoxazole-3-carboxylate ion and its 5-tetradecyloxy derivative

Didodecyldialkylammonium chloride and bromide (alkyl = Me, Et, n-Pr, n-Bu) accelerate the spontaneous decarboxylation of 6-nitrobenzisoxazole-3-carboxylate ion, 1,H, and its 5-tetradecyloxy derivative, 1,OTD. With most of these surfactants, first-order rate constants, kobs, go through maxima in very dilute surfactant and then decrease and go through minima as association colloids form. These phenomena are not explicable in terms of substrate-induced micellization. However, kobs increases in the N-alkyl sequence Me < Et < n-Pr < n-Bu, as is typical of decarboxylations in association colloids of single-chain surfactants. Reaction in premicelles is accelerated by an initial increase in 1,H. The factors that control relative rates of spontaneous reactions in premicelles and in the association colloids, in particular, depletion of water at the reaction center and association of substrate and quaternary ammonium centers, are discussed with respect to the roles of substrate and surfactant hydrophobicities.