Potentialities of using liquefied gases as alternative solvents to substitute hexane for the extraction of aromas from fresh and dry natural products

The potential of liquefied gases, n-butane, dimethyl ether, and HFO-1234ze as effective and green alternative solvents to substitute hexane has been evaluated for the extraction of aromatic compounds from dry lavender flowers (Lavandula angustifolia Mill.) and fresh orange peels (Citrus sinensis (L.) Osbeck). The performance of these liquefied gases as solvents has been evaluated in terms of yield, olfactory perception, and composition of the extract and also in terms of energy used, green and economic impacts, and regulatory issues. First, a predictive evaluation of the solvation performance of each solvent was carried out using simulations with the conductor-like screening model for real solvent. Then solid–liquid extractions were performed using liquefied gases at a laboratory scale to determine the extraction yield, the chemical composition, and the olfactory perception of each extract. Finally, the applicability of liquefied gas extractions in an industrial process was assessed, taking into account the potential impact on process, quality, safety, regulation, and environment.     

Recovery of spectral data using weighted canonical correlation regression

The weighted canonical correlation regression technique is employed for reconstruction of reflectance spectra of surface colors from the related XYZ tristimulus values of samples. Flexible input data based on applying certain weights to reflectance and colorimetric values of Munsell color chips has been implemented for each particular sample which belongs to Munsell or GretagMacbeth Colorchecker DC color samples. In fact, the colorimetric and spectrophotometric data of Munsell chips are selected as fundamental bases and the color difference values between the target and samples in Munsell dataset are chosen as a criterion for determination of weighting factors. The performance of the suggested method is evaluated in spectral reflectance reconstruction. The results show considerable improvements in terms of root mean square error (RMS) and goodness-of-fit coefficient (GFC) between the actual and reconstructed reflectance curves as well as CIELAB color difference values under illuminants A and TL84 for CIE1964 standard observer.     

Highly efficient protection of alcohols and phenols catalysed by tin porphyrin supported on MIL‐101

The catalytic activity of 5,10,15,20‐tetrakis(4‐aminophenyl)porphyrinatotin(IV) trifluoromethanesulfonate, [Sn^IV(TNH₂PP)(OTf)₂], supported on chloromethylated MIL‐101, was investigated in the trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS) and also their tetrahydropyranylation with 3,4‐dihydro‐2H‐pyran. Excellent yields, mild reaction conditions, short reaction times and reusability of the catalyst without significant decrease in its initial activity are noteworthy advantages of this supported catalyst. Copyright © 2015 John Wiley & Sons, Ltd.     

Quantification of Porous Properties of Shear Crystallized Lipids

The aim of this study was to investigate the impact that shear and composition have on the structural properties associated with the porous phases of lipids. To accomplish this aim, we developed eight main crystallized samples using cocoa butter (CB) or trilaurin (TL) in the presence or absence of monostearate (M) (5% w/w). The samples were sheared at 500 s⁻¹ using random (RS) or laminar (LS) shear at a cooling rate of 2 °C/min. Using the maximal ball (MB) algorithm, several empirical void measurements such as connectivity (z), pore and throat volume weighted radii (R₄₃), and void fraction (v) were quantified using 3D X-ray microcomputed tomography images. Most void features were identified as micropores (R ≥ 10 μm) possibly originating from the crystallization process and post-process crystal growth. Likewise, depending on the applied treatments, mechanisms impacting void formation were found to produce noticeable variation in v (0.019 to 0.139) and to determine whether void morphology was spherical, irregular, and/or highly connected.     

Guided waves characteristics of multi-walled carbon nanotubes

The theoretical analysis of propagation of guided waves in the multi-walled carbon nanotubes is presented within the framework of the classical electrodynamics. Electronic excitations of each wall of the system are modeled as an infinitesimally thin cylindrical layer of the π-electrons, whose dynamics are described by means of the fluid theory. General expressions of dispersion relations are obtained for the electromagnetic wave with the transverse magnetic and transverse electric modes, respectively, by solving Maxwell and fluid equations with appropriate boundary conditions.     

Oxidation reactions catalysed by molybdenum(VI) complexes grafted on UiO‐66 metal–organic framework as an elegant nanoreactor

A heterogeneous catalyst was synthesized by immobilizing Mo(CO)₃ in a UiO‐66 metal–organic framework. The benzene ring of the organic linker in UiO‐66 was modified via liquid‐phase deposition of molybdenum hexacarbonyl, Mo(CO)₆, as starting precursor to form the (arene)Mo(CO)₃ species inside the framework. The structure of this catalyst was characterized using X‐ray diffraction, and chemical integrity was confirmed using Fourier transform infrared and diffuse reflectance UV–visible spectroscopic methods. The metal content was analysed with inductively coupled plasma. Field emission scanning electron microscopy was used to measure particle size and N₂ adsorption measurements to characterize the specific surface area. This catalytic system was efficiently applied for epoxidation of alkenes and oxidation of sulfides. The Mo‐containing metal–organic framework was reused several times without any appreciable loss of its efficiency.     

Kinetic study of propane dehydrogenation and catalyst deactivation over Pt-Sn/Al2O3 catalyst

The kinetics of propane dehydrogenation and catalyst deactivation over Pt-Sn/Al₂O₃ catalyst were studied. Performance test runs were carried out in a fixed-bed integral reactor. Using a power-law rate expression for the surface reaction kinetics and independent law for deactivation kinetics, the experimental data were analyzed both by integral and a novel differential method of analysis and the results were compared. To avoid fluctuation of time-derivatives of conversion required for differential analysis, the conversion-time data were first fitted with appropriate functions. While the time-zero and rate constant of reaction were largely insensitive to the function employed, the rate constant of deactivation was much more sensitive to the function form. The advantage of the proposed differential method, however, is that the integration of the rate expression is not necessary which otherwise could be complicated or impossible. It was also found that the reaction is not limited by external and internal mass transfer limitations, implying that the employed kinetics could be considered as intrinsic ones.     

Chemical composition,protoscolicidal effects and acute toxicity of Pistacia atlantica Desf. fruit extract

The present study was designed to evaluate the chemical composition and scolicidal effects of Pistacia atlantica Desf. extract against protoscoleces of hydatid cysts and its acute toxicity in mice model. Various concentrations of the methanolic extract (5–50 mg/mL) were used for 10–60 min. Viability of protoscoleces was confirmed using eosin exclusion test (0.1%). Acute toxicity was also determined in mice model. The main components were β-myrcene (41.4%), α-pinene (32.48%) and limonene (4.66%). Findings demonstrated that P. atlantica extract at the concentrations of 25 and 50 mg/mL after 20 and 10 min of exposure killed 100% protoscoleces. The LD₅₀ of the intraperitoneal injection of the P. atlantica methanolic extract was 2.43 g/kg and the maximum non-fatal dose was 1.66 g/kg. Obtained results showed the potential of P. atlantica extract as a natural source with no significant toxicity for the production of new scolicidal agent to use in hydatid cyst surgery.     

In-silico exploration of noble gas dimer enforced by noncovalent interaction

Density functional calculations have been carried out to investigate the possibility of trapping of noble gas dimers by cyclo[18]carbon dimer. Parallel-displaced conformation of the cyclo[18]carbon dimer is found to be the minimum energy structure. Noncovalent interaction is found to hold the noble gas dimers. The lighter noble gases (He, Ne) posses weaker attractive interactions while the heavier one (Ar, Kr) are held by stronger attractive interactions forming genuine bonds. Each of the noble gas atoms in turn forms noncovalent interaction with the cyclo[18]carbon monomers. The bond dissociation energy of the noble gas dimers dramatically increases inside the cyclo[18]carbon dimer. Energy decomposition analysis reveals that dispersion plays the major role toward the stabilization energy.     

A palladium-catalyzed alkylation/direct arylation synthesis of nitrogen-containing heterocycles

A norbornene-mediated palladium-catalyzed sequence is described in which an alkyl-aryl bond and an aryl-heteroaryl bond are formed in one reaction vessel. The aryl-heteroaryl bond-forming step occurs via a direct arylation reaction. A number of six-, seven-, and eight-membered ring-annulated indoles, pyrroles, pyrazoles, and azaindoles were synthesized from the corresponding bromoalkyl azole and an aryl iodide.