From pregabalin to rac-3-cyano-5-methylhexanoic acid: an easy conversion which valorizes waste pregabalin enantiomer

(S)-(+)-3-Aminomethyl-5-methylhexanoic acid (pregabalin) was converted in one-pot to (S)-(−)-3-cyano-5-methylhexanoic acid (pregabalin nitrile) by N-dichlorination and double dehydrochlorination. The (S) β-cyanoacid was racemized under mild conditions by treatment with a base. This very simple and efficient procedure, applied to (R)-(−)-3-aminomethyl-5-methylhexanoic acid, would enable the recycling of the undesired enantiomer of pregabalin, an anticonvulsant drug manufactured by the synthesis of rac-3-aminomethyl-5-methylhexanoic acid and subsequent classical resolution.     

A time delay model for the diffusion of a new technology

In this paper, we propose a mathematical model with time delay to describe the process of diffusion of a new technology. This model is suitable for modeling diffusion processes of all those technologies that require great initial investments and public subsidies, such as technologies used for producing renewable energy. We consider external factors, such as the government policy and the production costs, that influence the decision of adoption of the new technology. We also consider the internal influence from adopters. The adoption process is described by a delay differential equation. The time delay represents the evaluation stage at which the potential consumers decide whether to adopt the new technology or not. A qualitative analysis is carried out in order to assess the stability of the equilibrium for certain parameters and to find the final level of adopters.     

Hyperfine Study on Mechanically Alloyed Fe–Mn Systems

Hyperfine Interactions - High-energy ball milling of Fe–Mn elemental powder mixtures has been carried out for different Mn concentrations, ranging from 0 to 90%. Mössbauer spectroscopy...     

Kinetic Resolution of sec‐Thiols by Enantioselective Oxidation with Rationally Engineered 5‐(Hydroxymethyl)furfural Oxidase

Various flavoprotein oxidases were recently shown to oxidize primary thiols. Herein, this reactivity is extended to sec‐thiols by using structure‐guided engineering of 5‐(hydroxymethyl)furfural oxidase (HMFO). The variants obtained were employed for the oxidative kinetic resolution of racemic sec‐thiols, thus yielding the corresponding thioketones and nonreacted R‐configured thiols with excellent enantioselectivities (E≥200). The engineering strategy applied went beyond the classic approach of replacing bulky amino acid residues with smaller ones, as the active site was additionally enlarged by a newly introduced Thr residue. This residue established a hydrogen‐bonding interaction with the substrates, as verified in the crystal structure of the variant. These strategies unlocked HMFO variants for the enantioselective oxidation of a range of sec‐thiols.     

Food safety: screening tests used to detect and quantify GMO proteins

GMO protein content in maize flours or fresh crops can be easily assessed by the enzyme-linked immunosorbent assays (ELISA) and immunochromatographic (lateral flow) strip tests commercially available. Therefore, ELISA can be seen as a useful tool for screening, for control purposes and for traceability implementation. In order to highlight the importance of monitoring GMO protein presence in food products and to investigate the performance of representative ELISA commercial kits, we evaluated three commercial kits by measuring the amount of Cry1Ab/Cry1Ac in IRMM certified reference materials. Presented at AOAC Europe/Eurachem Symposium March 2005, Brussels, Belgium     

Mössbauer study of Mg–Ni(Fe) alloys processed as materials for solid state hydrogen storage

Mg–Ni–Fe magnesium-rich intermetallic compounds were prepared following two distinct routes. A Mg₈₈Ni₁₁Fe₁ sample (A) was prepared by melt spinning Mg–Ni–Fe pellets and then by high-energy ball milling for 6 h the obtained ribbons. A (MgH₂)₈₈Ni₁₁Fe₁ sample (B) was obtained by high-energy ball milling for 20 h a mixture of Ni, Fe and MgH₂ powders in the due proportions. A SPEX8000 shaker mill with a 10:1 ball to powder ratio was used for milling in argon atmosphere. The samples were submitted to repeated hydrogen absorption/desorption cycles in a Sievert type gas–solid reaction controller at temperatures in the range 520?÷?590 K and a maximum pressure of 2.5 MPa during absorption. The samples were analysed before and after the hydrogen absorption/desorption cycles by X-ray diffraction and Mössbauer spectroscopy. The results concerning the hydrogen storage properties of the studied compounds are discussed in connection with the micro-structural characteristics found by means of the used analytical techniques. The improved kinetics of hydrogen desorption for sample A, in comparison to sample B, has been ascribed to the different behaviour of iron atoms in the two cases, as proved by Mössbauer spectroscopy. In fact, iron results homogeneously distributed in sample A, partly at the Mg₂Ni grain boundaries, with catalytic effect on the gas–solid reaction; in sample B, instead, iron is dispersed inside the hydride powder as metallic iron or superparamagnetic iron.     

Sequential + separable vs sequentially separable and another variation on selective separability

A space X is sequentially separable if there is a countable D ? X such that every point of X is the limit of a sequence of points from D. Neither “sequential + separable” nor “sequentially separable” implies the other. Some examples of this are presented and some conditions under which one of the two implies the other are discussed. A selective version of sequential separability is also considered.     

On some Variational Problems Involving Volume and Surface Energies

We show how some problems coming from different fields of applied sciences, such as physics, engineering, biology, admit a common variational formulation characterized by the competition of two energetic terms. We discuss related problems and techniques studied by the authors and collaborators in the recent past as well open problems and further possible research directions in these topics.     

Lower Semicontinuity Properties of Functionals with Free Discontinuities

This paper is concerned with functionals with free discontinuities, considered as depending on the set variable. A splitting operation divides the sets in which the functional takes low values in the union of a noise part and a macroscopic part. Then we show lower semicontinuity results on the limit of the macroscopic parts by Hausdorff distance, along minimizing sequences.     

Effects of Field Fluctuations,Losses, and Aberrations on the Sensitivity of a Michelson GW Antenna Using Squeezed Radiation

The sensitivity of an interferometric gravitational wave (GW) antenna operating above a few hundred Hertz is shot-noise limited. Sub-shot-noise sensitivity can be achieved by superimposing squeezed light on the laser field. The benefits of this approach are reduced in nonideal interferometers having fringe visibility less than unity, as pointed out by Gea-Banacloche and Leuchs and recently discussed by Chickarmane. Here, we consider an interferometer described by a set of coefficients V_l^(k), V_sq^(k), V_lsq^(k) depending on the misalignment, mismatching, and aberrations of the optical systems, as well as on the asymmetry of the beam splitter and the two-arm losses. Due to the presence of terms proportional to the product of laser times squeezed fields, we have taken into account the amplitude fluctuations of a_l. A simple model of the squeezed vacuum light, produced by a degenerate optical parametric oscillator (OPO), is used for calculating the dependence of the spectral density of the output of a GW antenna on the fluctuations of the OPO-cavity resonance frequency, the pump amplitude fluctuation, and the nonlinear-crystal-temperature drift. A set of figures η_sq± and r_lsq±⁽²⁾ are introduced for describing the effects of the amplitude fluctuations and the relative line width γ_la on the spectral density of the quadrature phase operator X = a_la_sq⁺ h.c.