Behaviour of the antioxidant tert-butylhydroquinone on the storage stability and corrosive character of biodiesel

The behaviour of the antioxidant tert-butylhydroquinone (TBHQ) on the storage stability of biodiesel was investigated. Storage conditions were simulated through static immersion corrosion tests in biodiesel (with and without TBHQ) using copper coupons. Measurements of oxidation stability (Rancimat induction period) and metal release at different stages of corrosion were performed. After 24 h of the static immersion test, the neat and TBHQ-doped biodiesels presented induction times below the EN 14214 limit (6 h). Copper release was more intense in the neat biodiesel which evidenced that TBHQ retarded the corrosion process as a corrosion inhibitor. Ion trap–time-of-flight mass spectrometry (IT–TOF-MS) revealed the presence of considerable amounts of tert-butylquinone (TBQ) in the TBHQ-doped biodiesel exposed to the corrosion process. As TBHQ molecules adsorb at the copper surface to inhibit corrosion, these molecules are catalytically oxidised to TBQ. IT–TOF-MS also indicated the formation of new molecules of high molecular weight only presented in the TBHQ-doped biodiesel deteriorated by the corrosion process. MS² spectra gave clear evidence of the formation of new complexes between free radicals of long-chain molecules (fatty acid derivatives) and TBQ radicals during biodiesel deterioration.     

Synthesis and Biological Evaluation of RGD and isoDGR–Monomethyl Auristatin Conjugates Targeting Integrin αVβ3

This work reports the synthesis of a series of small-molecule–drug conjugates containing the α_Vβ₃-integrin ligand cyclo[DKP-RGD] or cyclo[DKP-isoDGR], a lysosomally cleavable Val-Ala (VA) linker or an “uncleavable” version devoid of this sequence, and monomethyl auristatin E (MMAE) or F (MMAF) as the cytotoxic agent. The conjugates were obtained via a straightforward synthetic scheme taking advantage of a copper-catalyzed azide–alkyne cycloaddition as the key step. The conjugates were tested for their binding affinity for the isolated α_vβ₃ receptor and were shown to retain nanomolar IC₅₀ values, in the same range as those of the free ligands. The cytotoxic activity of the conjugates was evaluated in cell viability assays with α_vβ₃ integrin overexpressing human glioblastoma (U87) and human melanoma (M21) cells. The conjugates possess markedly lower cytotoxic activity than the free drugs, which is consistent with inefficient integrin-mediated internalization. In almost all cases the conjugates featuring isoDGR as integrin ligand exhibited higher potency than their RGD counterparts. In particular, the cyclo[DKP-isoDGR]-VA-MMAE conjugate has low nanomolar IC₅₀ values in cell viability assays with both cancer cell lines tested (U87: 11.50±0.13 nm ; M21: 6.94±0.09 nm ) and is therefore a promising candidate for in vivo experiments.     

TNF-α Blocker Effect of Naringenin-Loaded Sericin Microparticles that Are Potentially Useful in the Treatment of Psoriasis

This study aims to evaluate the effect of combined use of the racemic flavanone Naringenin (NRG) and the protein sericin as TNF-α blockers. Sericin (SMs) and (R/S) NRG-loaded Sericin (SNRGMs) microparticles were prepared by spray-drying, characterized in terms of morphology and particle size distribution, and encapsulation efficiency was determined. Concerning morphology and particle size distribution of microparticles, results indicated that they were not affected by the presence of NRG. The encapsulation efficiency was almost quantitative (93%), thus proving that sericin can be advantageously loaded with (R/S) NRG. Biological evaluation of (R/S) NRG, SMs and SNRGMs was then performed in lipopolysaccharide (LPS)-stimulated human peripheral blood mononuclear cells (hPBMC). SNRGMs resulted cytotoxic at the higher dose used (200 μg/mL) and the effect was greater than (R/S) NRG alone. Moreover, even if sericin alone was not effective in suppressing LPS-induced serum TNF-α levels, SNRGMs loaded with 9.3% of (R/S) NRG were significantly more potent than (R/S) NRG alone. In summary, this study provides the proof of concept that sericin-based microspheres loaded with TNF-α-blockers could contribute to the down regulation of the cytokine and represents the starting point for the development of new topical formulations for the treatment of middle-stage psoriasis.     

Rheological behaviour of some amphiphilic β‐cyclodextrin‐based azo aromatic polyurethanes in N,N‐dimethylformamide solutions

Amphiphilic β‐cyclodextrin‐based azo aromatic poly(ether urethane)s with different soft segment lengths have been synthesized and characterized. Hydrogen bonding in these systems was demonstrated by Fourier transform infrared spectroscopy analysis (carbonyl stretching region). A rheological study was performed on solutions of the synthesized poly(ether urethane)s in N,N‐dimethylformamide at various concentrations and temperatures by employing parallel plate geometry, and a comparative evaluation of the influence of the structural components on the viscometric responses was performed. The rheological behaviour was found to be strongly dependent on the chemical composition of the synthesized polyurethanes which promotes self‐assembly and structuring in solution. Hard segment content and polymer concentration influence pseudoplastic shear‐thinning flow behaviour. The rheology can be interpreted in terms of hydrophobic associations and chain entanglements and a hydrogen bonding network occurring in solution. The start‐up flow of the polymer solutions is determined by the lifetime of the associative polymer segments. Shear stress plateaux indicative of ‘shear banding’ behaviour explained by the structuring of the polymer solutions at increased temperatures were obtained. The studied amphiphilic polyurethane solutions are thermoresponsive systems exhibiting viscosity increase with increasing temperature contrary to the usual Arrhenius thermo‐thinning behaviour. At constant shear rate viscosity was found to increase with increasing temperature due to thermo‐association. © 2014 Society of Chemical Industry     

Enlargement of Submicron Gas‐Borne Particles by Heterogeneous Condensation for Energy‐Efficient Aerosol Separation

To improve the efficiency of aerosol separation, a process sequence for particle enlargement by condensation of water vapor on their surface is suggested. The presented method makes use of packed columns in non‐equilibrium operation to achieve supersaturation, which is required for droplet growth. Although this method is known for several years, it is not widely used in industrial processes and still needs accurate investigations for consolidation and establishment. The simulation tool AerCoDe3.0 for predicting saturation and particle growth in packed columns allows investigating the thermal energy consumption under various operation conditions. Based on the results obtained in this study, optimized arrangements of columns, which are applicable as preconditioning step for existing particle separators, are proposed.     

EZH2 Down-Regulation Exacerbates Lipid Accumulation and Inflammation in in Vitro and in Vivo NAFLD

Non-alcoholic fatty liver disease (NAFLD) is one of the most prevalent, chronic liver diseases, worldwide. It is a multifactorial disease caused by complex interactions between genetic, epigenetic and environmental factors. Recently, several microRNAs, some of which epigenetically regulated, have been found to be up- and/or down-regulated during NAFLD development. However, in NAFLD, the essential role of the Polycomb Group protein Enhancer of Zeste Homolog 2 (EZH2), which controls the epigenetic silencing of specific genes and/or microRNAs by trimethylating Lys27 on histone H3, still remains unknown. In this study, we demonstrate that the nuclear expression/activity of the EZH2 protein is down-regulated both in livers from NAFLD rats and in the free fatty acid-treated HepG2. The drop in EZH2 is inversely correlated with: (i) lipid accumulation; (ii) the expression of pro-inflammatory markers including TNF-α and TGF-β; and (iii) the expression of miR-200b and miR-155. Consistently, the pharmacological inhibition of EZH2 by 3-Deazaneplanocin A (DZNep) significantly reduces EZH2 expression/activity, while it increases lipid accumulation, inflammatory molecules and microRNAs. In conclusion, the results of this study suggest that the defective activity of EZH2 can enhance the NAFLD development by favouring steatosis and the de-repression of the inflammatory genes and that of specific microRNAs.     

Polydimethylsiloxanes Cross-Linked by 4,4′-(1,3-Phenylenedioxy)-Dianiline within in situ Generated Silica Network

Polydimethylsiloxanes side-functionalized in different degrees with chloromethyl groups were reacted with 4,4′-(1,3-phenylenedioxy)-dianiline when the secondary amino groups formation and cross-linking occur. The reactions were carried out in a silica sol-gel system and thus two networks are simultaneously formed: siloxane-organic network and the silica one. Different techniques were used to characterize the formed systems: FTIR to verify the structure, DMA for analysis of the thermomechanical behavior, SEM and AFM for the evaluation of the morphology and surface topography. The elemental distribution within the samples was determined by EDX. The water vapours sorption capacity was measured in the dynamic regime.     

STRUCTURAL CHANGES AND MASS TRANSFER DURING GLUCOSE INFUSION OF APPLES AS AFFECTED BY BLANCHING AND PROCESS VARIABLES

ABSTRACT

The effect of process variables and blanching on the rate of dewatering of apple slices through immersion in glucose solutions was analyzed. The adequacy of the Hawkes and Flink's and Peleg's models for fitting the rate data was evaluated as well as the structural changes produced in the tissue subjected to osmotic process. High concentration values (33-42 % (w/w)) of the soaking solution favored significantly water loss (WL) but only slightly affected solid gain (SG). Increasing system temperature over the range 20-50 °C generally provided an increase in WL and in SG. The increase in thickness decreased significantly both mass transfer rates. The use of sucrose instead of glucose lead to a greater SG while blanched samples showed higher rates of WL and SG. Microscopic studies revealed that, when applying short treatments, cells appeared slightly shrinked and cells walls folded. After long treatments, although an extensive