Pressurized Solvent Extraction of Paulownia Bark Phenolics

Paulownia bark is mostly utilized jointly with wood, but the possibility of a separate valorization through the pressurized extraction of bark bioactives has been assessed. Subcritical water extraction and supercritical CO₂ extraction are green technologies allowing shorter times than conventional solvent extraction under atmospheric shaken conditions. Subcritical water extraction was carried out at temperatures ranging from 140 to 240 °C and supercritical CO₂ extraction was performed at different pressures (10, 20 and 30 MPa), temperatures (35, 45 and 55 °C) and ethanol concentrations (0, 10 and 15% (w/w)). Subcritical water extraction under a non-isothermal operation during heating up to 160 °C (19 min) provided extraction yields up to 30%, and the extracts contained up to 7% total phenolics with an ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) radical scavenging capacity equivalent to 35% the activity of Trolox, whereas at 240 °C, the yield decreased to 20%, but the phenolic content reached 21%, and the antiradical activity was equivalent to 85% of Trolox. Supercritical CO₂ extraction at 30 MPa, 45 °C and 30 min reached a global yield of 2% after 180 min of extraction, but the product showed very low antiradical capacity. Gallic acid, vanillic acid, vanillin and apigenin were the major phenolic compounds found in the extracts.     

Confirmation of a nanohybrid shish‐kebab (NHSK) structure in composites of PET and MWCNTs

Here, the confirmation of an oriented nanohybrid shish‐kebab (NHSK) crystalline structure in a series of composites of poly(ethylene terephthalate) (PET) and multiwall carbon nanotubes (MWCNTs) is reported. The combined use of small‐ and wide‐angle X‐ray scattering (SAXS/WAXS) and thermal analysis has been used to investigate the morphology development in PET‐MWCNT nanocomposites under hot isothermal crystallization conditions. The MWCNTs act as both heterogeneous nucleating agents and surfaces (oriented shish structures) for the epitaxial growth of PET crystallites (kebabs) giving an oriented crystalline morphology. In contrast, the PET homopolymer does not show any residual oriented crystalline morphology during isothermal crystallization but gave a sporadic nucleation of a classic unoriented lamellar structure with slower crystallization kinetics. The results provide a valuable insight into the role of MWCNTs as nanoparticulate fillers in the morphology development and subsequent modification of physical properties in engineering polymers. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 132–137     

Erratum to: Evaluation of Three Multiresidue Methods for the Determination of Pesticides in Marijuana (Cannabis sativa L.) with Liquid Chromatography-Tandem Mass Spectrometry

Marijuana (non-medical cannabis) is a well-recognized psychoactive herbal drug used for recreational purposes. The aim of this work is to describe and compare the performance and suitability of selected methods to analyze pesticide residues in marijuana. The fitness of three typical pesticide multiresidue methods [acetate buffered QuEChERS (method A), a modified citrate buffered QuEChERS (method B) and citrate buffered QuEChERS (method C)] were tested in marijuana through the LC–MS/MS determination of 61 LC amenable pesticides. Considering recoveries at the highest level for the selected pesticides in marijuana, from the 61 target analytes, 37 (method A), 40 (method B) and 46 (method C) compounds gave accurate results (70–120 % range). Method C showed the best performance for the target analytes in terms of recoveries, precision, limits of quantitation and matrix effect. Marijuana showed to be a highly complex matrix. Most analytes suffered high signal suppression (ME <−50 %) for method B while medium (−50 to 20 %) to low (−20 to 0 %) signal suppression was found for methods A and C. Moreover, high coelution of coextractives with the target analytes was observed. A pilot survey with real samples revealed that seized and legally produced marijuana samples contained pesticides. Residues of diazinon (0.03 mg kg⁻¹), tebuconazole (0.19 mg kg⁻¹) and teflubenzuron (0.11 mg kg⁻¹) were simultaneously detected in one marijuana sample. The establishment of MRLs in a legal consumption scenario such as in Uruguay seems to be necessary in the near future.

     

Mathematical formulation and validation of the Be-FAST model for Classical Swine Fever Virus spread between and within farms

Classical Swine Fever is a viral disease of pigs that causes severe restrictions on the movement of pigs and pig products in the affected areas. The knowledge of its spread patterns and risk factors would help to implement specific measures for controlling future outbreaks. In this article, we describe in detail a spatial hybrid model, called Be-FAST, based on the combination of a stochastic Individual-Based model (modeling the interactions between the farms, considered as individuals) for between-farm spread with a Susceptible-Infected model for within-farm spread, to simulate the spread of this disease and identify risk zones in a given region. First, we focus on the mathematical formulation of each component of the model. Then, in order to validate Be-FAST, we perform various numerical experiments considering the Spanish province of Segovia. Obtained results are compared with the ones given by two other Individual-Based models and real outbreaks data from Segovia and The Netherlands.     

Structural and theoretical characterization of a new twisted 4′‐substituted terpyridine compound: 4′‐(isoquinolin‐4‐yl)‐2,2′:6′,2′′‐terpyridine

4′‐Substituted derivatives of 2,2′:6′,2′′‐terpyridine with N‐containing heteroaromatic substituents, such as pyridyl groups, might be able to coordinate metal centres through the extra N‐donor atom, in addition to the chelating terpyridine N atoms. The incorporation of these peripheral N‐donor sites would also allow for the diversification of the types of noncovalent interactions present, such as hydrogen bonding and π–π stacking. The title compound, C₂₄H₁₆N₄, consists of a 2,2′:6′,2′′‐terpyridine nucleus (tpy), with a pendant isoquinoline group (isq) bound at the central pyridine (py) ring. The tpy nucleus deviates slightly from planarity, with interplanar angles between the lateral and central py rings in the range 2.24 (7)–7.90 (7)°, while the isq group is rotated significantly [by 46.57 (6)°] out of this planar scheme, associated with a short H_tpy…H_isq contact of 2.32 Å. There are no strong noncovalent interactions in the structure, the main ones being of the π–π and C—H…π types, giving rise to columnar arrays along [001], further linked by C—H…N hydrogen bonds into a three‐dimensional supramolecular structure. An Atoms In Molecules (AIM) analysis of the noncovalent interactions provided illuminating results, and while confirming the bonding character for all those interactions unquestionable from a geometrical point of view, it also provided answers for some cases where geometric parameters are not informative, in particular, the short H_tpy…H_isq contact of 2.32 Å to which AIM ascribed an attractive character.