Effect of extraction methods on kinetic,chemical composition and antibacterial activities of Tunisian Thymus vulgaris. L. essential oil

The present study aims to compare two innovative extraction techniques: microwave-assisted hydrodistillation (MAHD) and solvent-free microwave extraction (SFME) through traditional extraction techniques: hydrodistillation (HD) and steam distillation (SD) for their efficiency in the extraction of the volatile compounds from Tunisian Thymus vulgaris leaves; the kinetic, yield, composition and antibacterial activities of the essential oil were assessed in vitro. Results show that the essential oils extracted by microwaves were quantitatively (yield) similar to those obtained through the conventional methods, but qualitatively, essential oils analysed by gas chromatography–mass spectrometry (GC–MS) presented 17, 11, 11 and 8 compounds obtained through SFME, MAHD, SD and HD, respectively, mostly consisting of carvacrol (89.24–41.17%), followed by γ-terpinene (11.37–1.37%) and para-cymene (27.95–2.05%). The essential oils were screened for antibacterial activity against 5 microorganisms. All essential oils obtained by studied extraction methods showed the same resistance against Gram (?) and Gram (+) bacteria. The SFME method gave the best results: rapid kinetic of extraction (30 min vs. 35 min for MAHD, 120 min for SD, and 180 min for HD), less energy saving and cleanest process.     

Pistacia lentiscus extract as a green inhibitor for copper corrosion in 0.5 M of H2SO4: electrochemical characterization and theoretical investigations

Journal of Applied Electrochemistry - The current work aims to study the effect of Pistacia lentiscus (Pil) essential oil originating from Chefchaouen city, which is located in northeastern Morocco...     

Analysis of physicochemical properties during the processing of Yiluxian,a traditional chinese low‐salt fish product

Yiluxian, a traditional Chinese low‐salt fish product, has been produced manually for decades. However, its quality depends on worker experience and varies owing to the lack of specific scientific guidelines for uniform production. This study investigated the changes in physicochemical properties under different salt concentrations and explored the principles underlying the low‐salt pickling process. The NaCl content of gutted fish increased to 3.82% in brining, and it decreased significantly to 1.15% after desalting. The colour of Yiluxian was not significantly different from that of raw fish (P > 0.05). The hardness, springiness, resistance and chewiness decreased by 12%, 9%, 27% and 19%, respectively, while cohesiveness did not change significantly (P > 0.05). Furthermore, Yiluxian is preferred over commonly salted fish for superior sensory profile. Our findings demonstrated the changes in various characteristics during pickling were expected to facilitate the stabilisation and uniformity of the quality and industrial production of this traditional food product.     

Measured infrared optical cross sections for a variety of chemical and biological aerosol simulants

We conducted a series of spectral extinction measurements on a variety of aerosolized chemical and biological simulants over the spectral range 3-13 microm using conventional Fourier-transform IR (FTIR) aerosol spectroscopy. Samples consist of both aerosolized particulates and atomized liquids. Materials considered include Bacillus subtilis endospores, lyophilized ovalbumin, polyethylene glycol, dimethicone (SF-96), and three common background materials: kaolin clay (hydrated aluminum silicate), Arizona road dust (primarily SiO2), and diesel soot. Aerosol size distributions and mass density were measured simultaneously with the FTIR spectra. As a result, all optical parameters presented here are mass normalized, i.e., in square meters per gram. In an effort to establish the utility of using Mie theory to predict such parameters, we conducted a series of calculations. For materials in which the complex indices of refraction are known, e.g., silicone oil (SF-96) and kaolin, measured size distributions were convolved with Mie theory and the resultant spectral extinction calculated. Where there was good agreement between measured and calculated extinction spectra, absorption, total scattering, and backscatter were also calculated.     

A new IMM algorithm using fixed coefficients filters (fastIMM)

In this paper we present an new approach based on two filters αβ$\alpha \beta$ and αβγ$\alpha \beta \gamma$ using Interacting Multiples Models (IMM) design instead of a Kalman filter second and third order for the tracking a single maneuver target. The comparison between the proposed filter and the IMM improves the computing time amount about 60% while having a high accuracy.     

Mechanical stresses and crack analysis of concrete under the hygrothermic effect

The hygrothermal process can change the porosity and the permeability of concrete, causing the initiation and the growth of the cracks, and thus deteriorating the integrity of the concrete structure. A numerical formulation based on the finite element method is developed to carry out the simulation of the initiation and the propagation of the cracks caused by the coupled field of thermal transfer and moisture transport. An original concept based on three-dimensional stress state of the integration points in each finite element is described. The global relative crack density is used to denote the cracking state of the entire concrete structure, which may serve as an appropriate index to evaluate the overall deterioration level of the structure.     

In situ measurement of the infrared absorption and extinction of chemical and biologically derived aerosols using flow-through photoacoustics

In an effort to establish a more reliable set of optical cross sections for a variety of chemical and biological aerosol simulants, we have developed a flow-through photoacoustic system that is capable of measuring absolute, mass-normalized extinction and absorption cross sections. By employing a flow-through design we avoid issues associated with closed aerosol photoacoustic systems and improve sensitivity. Although the results shown here were obtained for the tunable CO2 laser waveband region, i.e., 9.20-10.80 microm, application to other wavelengths is easily achievable. The aerosols considered are categorized as biological, chemical, and inorganic in origin, i.e., Bacillus atrophaeus endospores, dimethicone silicone oil (SF-96 grade 50), and kaolin clay powder (alumina and silicate), respectively. Results compare well with spectral extinction measured previously by Fourier-transform infrared spectroscopy. Comparisons with Mie theory calculations based on previously published complex indices of refraction and measured size distributions are also presented.