Cell and matrix morpho-functional analysis in chondrocyte micromasses

Micromass cultures represent a convenient means of studying chondrocyte physiology in the context of a tridimensional culture model. In this study, we present the first ultrastructural analysis of the distribution and organization of the extracellular components in micromasses in comparison with their cartilaginous counterparts. Primary chondrocytes obtained from osteoarthritis patients were pelleted in micromasses. Transmission electron microscopy and immunofluorescence were used to evaluate the distribution of major extracellular matrix proteins, i.e., aggrecan, chondroitin-4-sulfate, chondroitin-6-sulfate, and collagen I and II. Both approaches revealed a number of morphological features shared by micromass and cartilage chondrocytes. In particular, in micromasses, chondrocytes are in close contact with an organized extracellular matrix that adequately mimics that of cartilage. Cells were observed to establish specialized junctions for cell-extracellular matrix crosstalk. Noteworthy, cells seem endowed in a chondroitin sulfate-rich microenvironment, and thus possibly ensuring the immobilization of chemokines, a family of molecules emerging in osteoarthritis pathogenesis, in a haptotactic-like gradient to the chondrocytes, which facilitates the binding to their receptors. To determine the suitability of this model to investigate osteoarthritis pathogenesis, a potential apoptotic stimulus (endothelial IL-8) was used, and ultrastructural analysis assessed apoptosis induction. Micromass cultures were proved to be an experimental technique providing a large number of properly differentiated chondrocytes, and thus allowing reliable biochemical and morphological studies. They represent, therefore, a novel approach to osteoarthritis investigation that promises more thorough understanding of chondrocyte physiology in osteoarthritis.     

Thermo‐oxidative stabilization of poly(lactic acid)‐based nanocomposites through the incorporation of clay with in‐built antioxidant activity

In this work, an innovative approach to overcome the issue of the poor thermo‐oxidative stability of polymer/clay nanocomposites is proposed. Specifically, biodegradable poly(lactic acid) (PLA)‐based nanocomposites, containing organo‐modified clay with in‐built antioxidant activity, were prepared. Through a two‐step chemical protocol, a hindered phenol antioxidant was chemically linked to the ammonium quaternary salt which was then intercalated between the clay platelets [(AO)OM‐Mt]. The nanocomposites were characterized and their thermo‐oxidative stability during melt processing and under long‐term thermal test conditions was investigated. PLA nanocomposites containing the (AO)OM‐Mt showed higher oxidative stability, along with better clay dispersion, compared to PLA‐nanocomposites containing commercial clay and a free hindered phenol antioxidant. Obtained results can be explained considering that (AO)OM‐Mt may act locally, at the interface, between the silicate layers and the polymer macromolecules, thus contributing to the observed improved stability of the polymer both during processing and under long‐term thermal‐oxidative conditions. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44974.     

Partial Characterization of Nine Bacteriocins Produced by Lactic Acid Bacteria Isolated from Cold-Smoked Salmon with Activity against Listeria monocytogenes

Nine LAB bacteriocin-producers, isolated from vacuum-packaged cold-smoked salmon (CSS), were phenotypically and genotypically identified as Lactobacillus curvatus, Lactobacillus delbrueckii, Lactobacillus fermentum, Enterococcus faecium, and Pediococcus acidilactici. Their bacteriocins were partially characterized. The antimicrobial spectrum was determined against Listeria monocytogenes, E. faecalis, E. faecium, and Staphylococcus aureus. The molecular size of bacteriocins ranged from 2.8 to 4.5 kDa. They were inactivated by treatment with proteolytic enzymes but not by lipolytic or glycolytic enzymes. Maximal activity against L. monocytogenes ranged between 800 and 10000 AU/mL at pH 6.5. Most of the bacteriocins maintained full activity in a pH range of 2.0 to 8.0 but were partially or completely inactivated at pH 10.0. After heating at 60°C and 100°C, only two bacteriocins from Lb. curvatus strains partially lost activity. All bacteriocins showed a narrow spectrum of activity and a high anti-listerial activity, which is characteristic of the class IIa bacteriocins. Isolated bacteriocin-producing LAB could be used successfully in the bio-preservation of CSS and development of new potential bio-preservatives for CSS active against L. monocytogenes.     

Studies on the catalytic dechlorination and abatement of chlorided VOC: the cases of 2-chloropropane, 1,2-dichloropropane and trichloroethylene

The conversion of monochloropropanes and dichloropropanes over acid catalysts has been investigated in the presence of oxygen. In the temperature range of 450–550 K, dehydrochlorination of monochloropropanes to propene and HCl occurs selectively over silica–alumina, while significant formation of chlorinated by-products is observed over ZSM5 zeolite catalyst even at higher temperatures. Dichloropropanes conversion over silica–alumina catalyst gives rise mainly to chloropropenes in the temperature range 500–700 K. CO_x are predominant products only at the highest reaction temperatures (just above 700 K). Water vapor in the feed only slightly affects conversions and selectivities. Deactivation processes occur upon dichloropropane conversion, mainly due to coke deposition.

The conversion of highly chlorinated compounds, such as trichloroethylene (TCE) has been tested over silica–alumina and over HY zeolite in the presence of water vapor in the so-called “steam reforming” conditions (HVOC:water=1:2). With diluted feed (1200 ppm) on HY, reaction occurs above 800 K and formation of chlorinated by-products is minimized, CO_x being the main reaction products. At higher HVOC concentrations conversion is obtained at even lower temperature (600 K), but no more negligible by-products formation has been detected. In our conditions zeolite catalyst is more effective in TCE total conversion than silica–alumina.     

Isostructural organic–inorganic hybrids of P,P-diphenyl-methylenediphosphinate (CH2(P(Ph)O2)2) with divalent transition metals

New organic–inorganic hybrid materials have been synthesized by reaction in water solution of manganese, cobalt or nickel acetates with P,P^′-diphenylmethylenediphosphinic acid and all the two-dimensional structure coordination polymers obtained have been found to be isomorphous.     

Unconventional synthesis of Mg x C y Ni3: Synergic combination of mechanical alloying, SHS and isothermal heating

Several methods have been tested in order to prepare the perovskite type compound Mg _x C _y Ni₃ applying the mechanical alloying (MA), the self-propagating high-temperature synthesis (SHS) and the isothermal heating techniques in the different steps of preparation. These methods may be summarized as follows: method MCN-1) synthesis of the Mg _x C _y Ni₃ phase through MA of Mg₂Ni (previously synthesised by isothermal heating) and selected amounts of graphite and Ni, followed by isothermal treatment; method MCN-2) synthesis of the Mg _x C _y Ni₃ phase applying the SHS technique using powder compacts; method MCN-3) synthesis of an eutectic sample composed of Ni and MgNi₂ by means of isothermal heating, subsequent MA with graphite and final synthesis of Mg _x C _y Ni₃ by means of SHS. The methods MCN-2 and MCN-3 proved their validity to the synthesis of the desired compound with two main important results: complete conversion of the reactants into Mg _x C _y Ni₃ and control of the stoichiometry in the final product. For instance method MCN-1 shows instead a very low degree of conversion of the reactants. All the phases obtained after each preparation step (MA, SHS, isothermal heating) have been characterized by means of X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) coupled with electron dispersive spectroscopy (EDS).     

Volatile compounds from Chétoui olive oil and variations induced by growing area

Fruits from the same variety of Olea europaea L., grown under different environmental conditions in the north of Tunisia, were harvested at the same ripening degree and immediately processed. The volatile profile of virgin olive oils was established using solid phase, micro-extraction (SPME) and gas chromatography-mass spectrometry (GC-MS). Compounds belonging mainly to the following chemical classes characterised the volatile profiles: esters, aldehydes, ketons, aliphatic alcohols and hydrocarbons. Significant differences in the proportions of volatile constituents from oils of different geographical origins were detected and the major volatile in approximately 50% of the oil samples was the aldehyde (E)-2-hexenal. The results suggest that, beside the genetic factor, environmental conditions influence the volatile formation.     

Improving the Property–Function Tuning Range of Thiophene Materials via Facile Synthesis of Oligo/Polythiophene‐S‐Oxides and Mixed Oligo/Polythiophene‐S‐Oxides/Oligo/Polythiophene‐S,S‐Dioxides

A platform is described for the first time for the facile synthesis of oligo‐ and polythiophene‐S‐oxides and the corresponding ‐S,S‐dioxides in short times, mild conditions, high yields. Employing ultrasound assistance, brominated thiophenes are selectively mono‐ or dioxygenated at room temperature. These building blocks are then combined with metalated thiophenes via microwave‐assisted cross‐coupling reactions through a “Lego‐like” strategy to afford unprecedented oligo/polythiophene‐S‐oxides and mixed ‐S‐oxides/‐S,S‐dioxides. It is demonstrated that depending on the number, type, and sequence alternation of nonoxygenated, monooxygenated, and dioxygenated thiophene units a very wide property–function tuning can be achieved spanning from frontier orbital energies and energy gaps, to charge transport characteristics and supramolecular H‐bonding interactions with specific proteins inside live cells.