Quality enhancement of the abundant under‐valued crustacean,lobster krill (Munida spp.), during its chilled storage

Lobster krill (Munida genus) represents an under‐valued crustacean frequently caught on European fishing banks. In this work, its sensory, microbiological and biochemical qualities were evaluated during chilled storage. Additionally, the effects of a prestorage antimelanosic treatment consisting of soaking in sodium metabisulphite (SMB) solutions at two different concentrations (0.25% and 0.75%) were also studied. SMB prestorage treatment provided lobster specimens that still exhibited acceptable sensory quality after 10 days of storage, while control specimens were unacceptable at that time. SMB treatment also resulted in a significant (P < 0.05) inhibition of microbial growth, mainly of Enterobacteriaceae, psychrotrophes and proteolytic bacteria. Low lipid oxidation levels were observed for all batches; however, a significantly higher (P < 0.05) retention of polyunsaturated fatty acids was found in SMB‐treated lobster, especially in the 0.75% SMB batch. The results presented here open the way to the potential commercialisation of currently under‐utilised lobster krill as a chilled product.     

Effect of biodegradable film (lyophilised alga Fucus spiralis and sorbic acid) on quality properties of refrigerated megrim (Lepidorhombus whiffiagonis)

The effect of replacing the on‐board currently employed polyethylene film by a novel type of environmentally friendly packaging was studied. For it, a polylactic acid (PLA) biodegradable film including lyophilised alga Fucus spiralis and sorbic acid was applied during megrim (Lepidorhombus whiffiagonis) refrigeration and its effect on fish quality loss was evaluated. Thus, sensory assessment showed that samples wrapped up with PLA film including 8% alga and 1% sorbic acid were still acceptable on day 11, while control fish specimens (kept under polyethylene film) were rejected at that time. Under such biodegradable film condition, a preservative effect was also implied according to chemical indices assessment related to microbial activity (trimethylamine–N) and lipid oxidation development (peroxide and fluorescent compounds formation); additionally, lower mean numbers for different microbiological groups (aerobes, Enterobacteriaceae and psychrotrophs) were detected. This result provides a promising replacement strategy to enhance refrigerated fish quality and reduce the waste material content.     

Density-driven flow and solute transport problems. A 2-D numerical model based on the network simulation method

The network simulation method, based on the formal equivalence between physical systems and electrical networks, solves numerical problems of relatively mathematical complexity in a versatile, efficient and computationally fast way. In this paper, the method is applied for the first time to the design of a general purpose model for simulating two-dimensional transient density-driven flow and solute transport through porous media, a mathematical model made up by coupled, nonlinear differential equations. Using the Boussinesq approximation and the stream function formulation, the model is used to solve two typical problems related with groundwater flows. Isochlor concentration and stream function curves are presented and successfully compared with those of other authors. Simulation is carried out using the digital computer program Pspice with relatively low computing times.     

Estrogenic activity of polychlorinated biphenyls present in human tissue and the environment

This study evaluated the estrogenicity of polychlorinated biphenyls (PCBs) present in environmental media and human tissue and assessed exposure pathways for PCB-derived estrogenic potency in air, soil, and dust from New Bedford, MA, an area with a PCB-contaminated Superfund site. Thirty-four PCB congeners were assayed for estrogenic potency using E-SCREEN, an assay based on the estrogen-dependent proliferation of MCF-7 cells in vitro. Childhood exposure to estradiol-equivalents via PCBs in environmental media was estimated byweighting previously reported New Bedford congener-specific concentrations by their relative estrogenic potency and published inhalation and soil ingestion rates. Thirteen congeners were weakly estrogenic in E-SCREEN: PCBs 17, 18, 30, 44, 49, 66, 74, 82, 99, 103, 110, 128, and 179. These PCBs were typically 6 orders of magnitude less potent than 17beta-estradiol, with proliferative potencies ranging from 0.0007% to 0.0040%. Of the environmental media assessed, air (inhalation) had the highest PCB-derived estradiol-equivalent exposure. PCB estrogenic potency information from this study provides an important resource both for preliminary estimation of routes of human exposure to xenoestrogens and for application to human health studies focused on estrogen-responsive health outcomes, such as reproductive development and related malignancies.     

Synthesis and characterization of cubic BC2N grown by reactive laser ablation

Cubic boron-carbon-nitrogen c-BC₂N films were synthesized in a laser ablation system using a target of B₄C with 99.99% of purity and silicon substrates (111). The discharge atmosphere for the films growth was a CH₄ + N₂ mixture. The substrate temperature increased from room temperature to 650 °C. The chemical composition and bonding configuration were studied by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES), finding B-N, B-C and C-C bonds. Moreover, the crystallographic microstructure was analyzed by means of X ray diffraction (XRD) and transmission electron microscopy (TEM), showing the presence of (111), (200) and (220) planes belonging to a diamond like cubic structure. Finally, an increase in the coating hardness as a function of the substrate temperature was observed, especially for temperatures higher than 530 °C.     

H2 Physisorbed on Graphane

We study the zero-temperature phase diagrams of H₂ adsorbed on the three structures predicted for graphane (chair, boat and washboard graphane), using a diffusion Monte Carlo technique. Graphane is the hydrogenated version of graphene, in which each carbon atom changes its hybridization to sp ³ and forms a covalent bond with a hydrogen atom. Our results show that the ground state of H₂ adsorbed on all three types of graphane is a $\sqrt{3}\times\sqrt{3}$ solid, similar to the structures found both for H₂ and D₂ on graphene. When the H₂ density increases, the system undergoes a first order phase transition to a triangular incommensurate solid. This change is direct in the case of washboard graphane, but indirect via different commensurate structures in the other cases. The total hydrogen weight percentage on the three graphane types in their ground states is in the range 10 % to 12 %, depending on if one or both graphane surfaces are covered with H₂.     

Performance of Φ-Sulfo Fatty Methyl Ester Sulfonate Versus Linear Alkylbenzene Sulfonate,Secondary Alkane Sulfonate and α-Sulfo Fatty Methyl Ester Sulfonate

Sulfoxidation of fatty acid methyl esters with SO_2, O₂ and ultraviolet light of appropriate wavelength, has led to the synthesis of methyl esters sulfonates or sulfoxylates, known as Φ-MES, because of the possible random position of SO₃ group in the alkyl chain. Aqueous solutions based on the sulfoxylated methyl ester of palmitic acid (Φ-MES C16) have been studied and compared to the leading types of surfactants used today: linear alkylbenzene sulfonate (LAS) secondary alkane sulfonate (SAS) and α-sulfo fatty methyl ester sulfonate (α-MES) with regard to solubility, performance and skin compatibility. The experimental results obtained indicate that Φ-MES C16 can be regarded as a potential component of detergent formulations and most likely also of body care products.