Fracture behavior and mechanical,thermal, and rheological properties of biodegradable films extruded by flat die and calender

The development of biodegradable materials for tailored applications, particularly in the field of polymeric films and sheets, is a challenging technological goal as well as a contribution to help protect the environment. Poly(lactic) acid (PLA) is a promising substitute for several oil-based polymers; however, to overcome its thermal and mechanical drawbacks, researchers have developed solutions such as blending PLA with polybutylene adipate terephthalate (PBAT), which is capable of increasing the ductility of the final material. In this study, PLA/PBAT binary blends, with minimum possible content of nonrenewable materials, were examined from processing, thermal, morphological, and rheological perspective. An optimized PLA/PBAT ratio was chosen as the polymeric basis to obtain a biodegradable formulation by adding a biobased plasticizer and appropriate fillers to produce a micrometer film with tailored flexibility and tear resistance. The processing technology involved flat-die extrusion, followed by calendering. The tearing resistance of the produced film was investigated, and the results were compared with literature data. A study on the essential work of fracture was implemented to explore the mode III out-of-plane fracture resistance starting from a trouser tear test.     

Neuroprotective Effects of Curcumin in Methamphetamine-Induced Toxicity

Curcumin (CUR), a natural polyphenol extracted from rhizome of the Curcuma longa L, has received great attention for its multiple potential health benefits as well as disease prevention. For instance, CUR protects against toxic agents acting on the human body, including the nervous system. In detail, CUR possesses, among others, strong effects as an autophagy activator. The present study indicates that CUR counteracts methamphetamine (METH) toxicity. Such a drug of abuse is toxic by disturbing the autophagy machinery. We profited from an unbiased, low variable cell context by using rat pheochromocytoma PC12 cell line. In such a system, a strong protection was exerted by CUR against METH toxicity. This was associated with increased autophagy flux, merging of autophagosomes with lysosomes and replenishment of autophagy vacuoles with LC3, which instead is moved out from the vacuoles by METH. This is expected to enable the autophagy machinery. In fact, while in METH-treated cells the autophagy substrates α-synuclein accumulates in the cytosol, CUR speeds up α-synuclein clearance. Under the effects of CUR LC3 penetrate in autophagy vacuoles to commit them to cell clearance and promotes the autophagy flux. The present data provide evidence that CUR counteracts the neurotoxic effects induced by METH by promoting autophagy.     

Electrosprayed Shrimp and Mushroom Nanochitins on Cellulose Tissue for Skin Contact Application

Cosmetics has recently focused on biobased skin-compatible materials. Materials from natural sources can be used to produce more sustainable skin contact products with enhanced bioactivity. Surface functionalization using natural-based nano/microparticles is thus a subject of study, aimed at better understanding the skin compatibility of many biopolymers also deriving from biowaste. This research investigated electrospray as a method for surface modification of cellulose tissues with chitin nanofibrils (CNs) using two different sources—namely, vegetable (i.e., from fungi), and animal (from crustaceans)—and different solvent systems to obtain a biobased and skin-compatible product. The surface of cellulose tissues was uniformly decorated with electrosprayed CNs. Biological analysis revealed that all treated samples were suitable for skin applications since human dermal keratinocytes (i.e., HaCaT cells) successfully adhered to the processed tissues and were viable after being in contact with released substances in culture media. These results indicate that the use of solvents did not affect the final cytocompatibility due to their effective evaporation during the electrospray process. Such treatments did not also affect the characteristics of cellulose; in addition, they showed promising anti-inflammatory and indirect antimicrobial activity toward dermal keratinocytes in vitro. Specifically, cellulosic substrates decorated with nanochitins from shrimp showed strong immunomodulatory activity by first upregulating then downregulating the pro-inflammatory cytokines, whereas nanochitins from mushrooms displayed an overall anti-inflammatory activity via a slight decrement of the pro-inflammatory cytokines and increment of the anti-inflammatory marker. Electrospray could represent a green method for surface modification of sustainable and biofunctional skincare products.     

A multinuclear solid-state magnetic resonance study of the interactions between the inorganic and organic coatings of BaSO4 submicronic particles

Silica-coated BaSO4 submicronic particles, modified on the surface by treatment with stearic acid, have been characterized by means of 29Si, 13C, and 1H magic-angle-spinning (MAS) high-resolution techniques, and low-resolution 1H-FID analysis. Two types of adsorbed water were identified; adsorbed either inside or on the surface of BaSO4, most of the latter being removed by the silica coating. Evidences of silica-stearic acid interactions were found involving either carboxylic acid or carboxylate functional groups, and occurring by means of hydrogen and/or covalent bonds. Stearic acid was present as monolayer only, its chain being mostly rigid, even though a small fraction was subjected to fast inter-conformational motions.     

Cellulose-based fiber spinning processes using ionic liquids

Cellulose - Cellulose, a natural, renewable, and environment friendly biopolymer, has been considered as a sustainable feedstock in the near future. However, only 0.3% of cellulose is today...     

Pollen discrimination and classification by Fourier transform infrared (FT-IR) microspectroscopy and machine learning

The discrimination and classification of allergy-relevant pollen was studied for the first time by mid-infrared Fourier transform infrared (FT-IR) microspectroscopy together with unsupervised and supervised multivariate statistical methods. Pollen samples of 11 different taxa were collected, whose outdoor air concentration during the flowering time is typically measured by aerobiological monitoring networks. Unsupervised hierarchical cluster analysis provided valuable information about the reproducibility of FT-IR spectra of the same taxon acquired either from one pollen grain in a 25 × 25 μm² area or from a group of grains inside a 100 × 100 μm² area. As regards the supervised learning method, best results were achieved using a K nearest neighbors classifier and the leave-one-out cross-validation procedure on the dataset composed of single pollen grain spectra (overall accuracy 84%). FT-IR microspectroscopy is therefore a reliable method for discrimination and classification of allergenic pollen. The limits of its practical application to the monitoring performed in the aerobiological stations were also discussed. Figure Traditional and innovative methods for the identification of airborne pollen grains     

Raman spectrum of graphene and graphene layers

Graphene is the two-dimensional building block for carbon allotropes of every other dimensionality. We show that its electronic structure is captured in its Raman spectrum that clearly evolves with the number of layers. The D peak second order changes in shape, width, and position for an increasing number of layers, reflecting the change in the electron bands via a double resonant Raman process. The G peak slightly down-shifts. This allows unambiguous, high-throughput, nondestructive identification of graphene layers, which is critically lacking in this emerging research area.     

Simulation of the plastic behavior of amorphous glassy bis-phenol-A-polycarbonate

A protocol for studying the plastic deformation of amorphous glassy polymers is presented. The protocol is based on a viable computational procedure which combines constant-stress molecular dynamics simulations and fixed-cell energy minimizations, followed by kinetic, configurational, and energy analyses. It is shown that the computational results can be accounted for within a "potential energy landscape" theoretical framework, in which the plastic transition is interpreted as a crossing between and a collapse onto each other of "ideal (thermodynamic) structures." The procedure is applied to bis-phenol-A-polycarbonate (BPA-PC), but is equally valid for a wide variety of polymeric species. Allowing for the limited size of the simulation cell, the high strain rate, and the fact that the simulation are conducted at low temperature, the values of the density, Young's modulus, yield strain, yield stress, activation energy, and activation volume are in fair agreement with the experimental data on BPA-PC. The analysis of the results shows that the plastic relaxation for this polymer has both a collective and cooperative character (as in classical percolation theories), involves a significant fraction of the simulation cell, and can be viewed as a "nanoscopic shear band."     

The intersection matrix of Brieskorn singularities

To each isolated singularity of a hypersurface of dimensionn, one associates the local fundamental groupG of the moduli space minus the discriminant locus, and a representation σ:G→Aut(H), whereH is then-homology group, with integer coefficients, of the non singular fibre. Although, in general it is very difficult to determine even a presentation ofG, we show that the image of σ can be computed rather easily, by exploiting some relations in a first aproximate presentation ofG, in the case of Brieskorn polynomials namely, polynomials of the type \(x_0^{a_0 } + \cdot \cdot \cdot + x_0^{a_n } \) . In this way we solve an open problem stated by Brieskorn [1] and Pham [8].