Development of a Novel Microwave Distillation Technique for the Isolation of Cannabis sativa L. Essential Oil and Gas Chromatography Analyses for the Comprehensive Characterization of Terpenes and Terpenoids,Including Their Enantio-Distribution

A microwave distillation method was optimized for the extraction and isolation of cannabis essential oil from fresh and dried hemp inflorescences. The developed method enabled us to obtain a distilled product rich in terpenes and terpenoid compounds, responsible of the typical and unique smell of the cannabis plant. The distillate from different hemp cultivars, including Kompolti, Futura 75, Carmagnola, Felina 32 and Finola were characterized by using a gas chromatograph equipped with both mass spectrometer and flame ionization detectors. In a single chromatographic run, the identity and absolute amounts of distilled compounds were determined. Peak assignment was established using a reliable approach based on the usage of two identification parameters, named reverse match, and linear retention index filter. Absolute quantification (mg g⁻¹) of the analytes was performed using an internal standard method applying the flame ionization detector (FID) response factors according to each chemical family. An enantio-GC-MS method was also developed in order to evaluate the enantiomeric distribution of chiral compounds, an analytical approach commonly utilized for establishing the authenticity of suspicious samples.     

FRP-strengthened reinforced concrete beams: a review and the assessment of cracking and deflection models

A review of some cracking and deflection models used for a structural analysis of FRP-strengthened reinforced concrete beams is presented, and, with reference to short-term deflections, a comparison between model predictions and experimental results is made. By using predictions provided by a nonlinear model derived from a cracking analysis, founded on slip and bond stresses, and experimental results for 63 FRP-strengthened beams, a modification of the well-known semi-empirical Branson’s formula to compute beam deflections is proposed. Finally, the efficiency of the modification is evaluated by comparison with experimental results.     

Maximum-entropy principle for nonlinear hydrodynamic transport in semiconductors

We present, in a strong nonlinear context, a full-band hydrodynamic approach by using the first 13 moments of the distribution function in the framework of extended thermodynamics. Following this approach we show that: (1) the full-band effects of the band structure are described accurately up to high electric fields both in homogeneous and nonhomogeneous conditions; (2) the effectiveness of the dissipation processes can be properly investigated, in homogeneous conditions, only in a strong nonlinear context; and (3) the hyperbolicity region of the system is very large, also in the nonlinear conditions. In this way, by using a strong nonlinear closure, it is possible to describe accurately the transport phenomena in submicron devices, when very high electric fields and field gradients occur (E ≈ 220 kV/cm, E/(dE/dx) ≈ 100 Å).     

Key interaction patterns in proteins revealed by cluster expansion of the partition function

The European Physical Journal E -     

Swollen-collapsed transition in random hetero-polymers

A lattice model of a hetero-polymer with random hydrophilic-hydrophobic charges interacting with the solvent is introduced, whose continuum counterpart has been proposed by Garel, Leibler and Orland [#!GLO!#]. The transfer matrix technique is used to study various constrained annealed systems which approximate at various degrees of accuracy the original quenched model. For highly hydrophobic chains an ordinary -point transition is found from a high temperature swollen phase to a low temperature compact phase. Depending on the type of constrained averages, at very low temperatures a swollen phase or a coexistence between compact and swollen phases are found. The results are carefully compared with the corresponding ones obtained in the continuum limit, and various improvements in the original calculations are discussed. Received: 10 April 1998 / Revised: 4 June 1998 / Accepted: 1st July 1998     

The key role of 3-glycidoxypropyltrimethoxysilane sol–gel precursor in the development of wearable sensors for health monitoring

Textiles represent an attractive class of materials for realizing wearable biosensors. Electronic textiles, or smart textiles, describe the convergence of electronics and textiles into fabrics, which are able to sense, compute, communicate, and actuate. As many different electronic systems can be connected to any clothing, a wearable system becomes more versatile, and the user can change its look depending on environmental changes and individual preference. In this review, we want to explain how it is possible to develop the sensing component of a wearable sensor by sol–gel method based on the use of opportune organofunctional trialkoxysilane precursors, such as 3-glycidoxypropyltrimethoxysilane. Results show that the halochromic dyestuffs are completely entrapped in the sol–gel coatings, both through chemical and physical interactions with the textile fabric. Moreover, a certain washing fastness was observed. Sensor films show excellent reproducibility, reversibility, and short response times, with dynamic ranges from pH 4.4–6.0 (Methyl Red), pH 6.0–7.0 (Nitrazine Yellow), and pH 4.5–8.3 (Litmus), respectively.

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Physics of thick polymers

We present the results of analytical calculations and numerical simulations of the behavior of a new class of chain molecules that we call thick polymers. The concept of the thickness of such a polymer, viewed as a tube, is encapsulated by a special three‐body interaction and impacts on the behavior both locally and nonlocally. When thick polymers undergo compaction because of an attractive self‐interaction, we find a new type of phase transition between a compact phase and a swollen phase at zero temperature with increasing thickness. In the vicinity of this transition, short tubes form space‐filling helices and sheets as observed in protein native‐state structures. With increasing chain length, or with an increasing number of chains, we numerically find a crossover from secondary‐structure motifs to a quite distinct class of structures akin to the semicrystalline phases of polymers or amyloid fibers in polypeptides. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 650–679, 2005     

Nonlinear stability in reaction-diffusion systems via optimal Lyapunov functions

We define optimal Lyapunov functions to study nonlinear stability of constant solutions to reaction-diffusion systems. A computable and finite radius of attraction for the initial data is obtained. Applications are given to the well-known Brusselator model and a three-species model for the spatial spread of rabies among foxes.     

Field equations for charge conducting fluids in electromagnetic fields

Previous relativistic theories of thermodynamics of fluid mixtures can be extended to include more independent variables. Here the particular case is considered of a 3-constituent mixture consisting of a non-conducting fluid and two charged fluids; extension to the general case is straightforward. A set of field equations is found for the determination of the fields, following the methods of extended thermodynamics. These equations are restricted by the entropy principle and by material objectivity, obtaining in this way a closed hyperbolic system of field equations.As a byproduct of these principles, interesting stringent inequalities are obtained for the relaxation times arising from the production terms.