On estimating the interface normal and curvature in piecewise linear interface calculation-volume of fluid approach for three-dimensional arbitrary meshes

Volume of fluid (VOF) method with its Piecewise Linear Interface Calculation (PLIC) reconstruction algorithm is one of the most popular approaches in numerical simulation of interfacial flows with a wide range of applications in different areas. In an effort to evaluate the similarity of the PLIC-generated planes in comparison with the exact interface, a point-cloud, based on the polygon centers of PLIC planes is extracted, which later is used to form a triangular grid that represents the estimated interface. The main objective of this article is to evaluate the interface geometrical properties based on the extracted triangular grid of the interface. The methods presented in this article, characterized by a higher spatially convergence ratio, are compared with the commonly used methods. The proposed methods are tested for two 3-dimensional general test cases, where an evident improvement is seen in calculation accuracy and spatial convergence of the errors of interface normal vector and curvature.     

Medicated Scaffolds Prepared with Hydroxyapatite/Streptomycin Nanoparticles Encapsulated into Polylactide Microfibers

The preparation, characterization, and controlled release of hydroxyapatite (HAp) nanoparticles loaded with streptomycin (STR) was studied. These nanoparticles are highly appropriate for the treatment of bacterial infections and are also promising for the treatment of cancer cells. The analyses involved scanning electron microscopy, dynamic light scattering (DLS) and Z-potential measurements, as well as infrared spectroscopy and X-ray diffraction. Both amorphous (ACP) and crystalline (cHAp) hydroxyapatite nanoparticles were considered since they differ in their release behavior (faster and slower for amorphous and crystalline particles, respectively). The encapsulated nanoparticles were finally incorporated into biodegradable and biocompatible polylactide (PLA) scaffolds. The STR load was carried out following different pathways during the synthesis/precipitation of the nanoparticles (i.e., nucleation steps) and also by simple adsorption once the nanoparticles were formed. The loaded nanoparticles were biocompatible according to the study of the cytotoxicity of extracts using different cell lines. FTIR microspectroscopy was also employed to evaluate the cytotoxic effect on cancer cell lines of nanoparticles internalized by endocytosis. The results were promising when amorphous nanoparticles were employed. The nanoparticles loaded with STR increased their size and changed their superficial negative charge to positive. The nanoparticles’ crystallinity decreased, with the consequence that their crystal sizes reduced, when STR was incorporated into their structure. STR maintained its antibacterial activity, although it was reduced during the adsorption into the nanoparticles formed. The STR release was faster from the amorphous ACP nanoparticles and slower from the crystalline cHAp nanoparticles. However, in both cases, the STR release was slower when incorporated in calcium and phosphate during the synthesis. The biocompatibility of these nanoparticles was assayed by two approximations. When extracts from the nanoparticles were evaluated in cultures of cell lines, no cytotoxic damage was observed at concentrations of less than 10 mg/mL. This demonstrated their biocompatibility. Another experiment using FTIR microspectroscopy evaluated the cytotoxic effect of nanoparticles internalized by endocytosis in cancer cells. The results demonstrated slight damage to the biomacromolecules when the cells were treated with ACP nanoparticles. Both ACP and cHAp nanoparticles were efficiently encapsulated in PLA electrospun matrices, providing functionality and bioactive properties.     

Interleukin-1β Modulation of the Mechanobiology of Primary Human Pulmonary Fibroblasts: Potential Implications in Lung Repair

Pro-inflammatory cytokines like interleukin-1β (IL-1β) are upregulated during early responses to tissue damage and are expected to transiently compromise the mechanical microenvironment. Fibroblasts are key regulators of tissue mechanics in the lungs and other organs. However, the effects of IL-1β on fibroblast mechanics and functions remain unclear. Here we treated human pulmonary fibroblasts from control donors with IL-1β and used Atomic Force Microscopy to unveil that IL-1β significantly reduces the stiffness of fibroblasts concomitantly with a downregulation of filamentous actin (F-actin) and alpha-smooth muscle (α-SMA). Likewise, COL1A1 mRNA was reduced, whereas that of collagenases MMP1 and MMP2 were upregulated, favoring a reduction of type-I collagen. These mechanobiology changes were functionally associated with reduced proliferation and enhanced migration upon IL-1β stimulation, which could facilitate lung repair by drawing fibroblasts to sites of tissue damage. Our observations reveal that IL-1β may reduce local tissue rigidity by acting both intracellularly and extracellularly through the downregulation of fibroblast contractility and type I collagen deposition, respectively. These IL-1β-dependent mechanical effects may enhance lung repair further by locally increasing pulmonary tissue compliance to preserve normal lung distension and function. Moreover, our results support that IL-1β provides innate anti-fibrotic protection that may be relevant during the early stages of lung repair.     

Effectiveness of combined preservation methods to extend the shelf life of Morcilla de Burgos

Morcilla de Burgos is the most famous blood sausage in Spain. However, while producers are interested in extending its shelf life, the consumer is increasingly demanding more natural food. This situation has led to the current search for new and mild preservation technologies. Two batches of four different products: control without any treatment, control with organic acid salts (CnOAS; a 3% mixture of potassium/sodium l-lactate), control with high hydrostatic pressure processing (CnHPP; 600MPa-10min), and a combination of both treatments (OAS+HPP), were carried out to evaluate any synergistic effect that occurs when combining OAS and HPP, and the influence of different preservative treatments on the spoilage bacterial population and their evolution. HPP (with or without addition of OAS) can be considered the most suitable method for preserving morcilla de Burgos as it does not produce negative changes in sensory attributes. No clear selective effect of different treatments on the composition of the spoilage bacteria was seen and similar spoilage patterns were observed independently of the preservation treatment used.     

Greatly enhanced arsenic shoot assimilation in rice leads to elevated grain levels compared to wheat and barley

Paired grain, shoot, and soil of 173 individual sample sets of commercially farmed temperate rice, wheat, and barley were surveyed to investigate variation in the assimilation and translocation of arsenic (As). Rice samples were obtained from the Carmargue (France), Do?ana (Spain), Cadiz (Spain), California, and Arkansas. Wheat and barleywere collected from Cornwall and Devon (England) and the east coast of Scotland. Transfer of As from soil to grain was an order of magnitude greater in rice than for wheat and barley, despite lower rates of shoot-to-grain transfer. Rice grain As levels over 0.60 microg g(-1) d. wt were found in rice grown in paddy soil of around only 10 microg g(-1) As, showing that As in paddy soils is problematic with respect to grain As levels. This is due to the high shoot/soil ratio of approximately 0.8 for rice compared to 0.2 and 0.1 for barley and wheat, respectively. The differences in these transfer ratios are probably due to differences in As speciation and dynamics in anaerobic rice soils compared to aerobic soils for barley and wheat. In rice, the export of As from the shoot to the grain appears to be under tight physiological control as the grain/shoot ratio decreases by more than an order of magnitude (from approximately 0.3 to 0.003 mg/kg) and as As levels in the shoots increase from 1 to 20 mg/kg. A down regulation of shoot-to-grain export may occur in wheat and barley, but it was not detected at the shoot As levels found in this survey. Some agricultural soils in southwestern England had levels in excess of 200 microg g(-1) d. wt, although the grain levels for wheat and barley never breached 0.55 microg g(-1) d. wt. These grain levels were achieved in rice in soils with an order of magnitude lower As. Thus the risk posed by As in the human food-chain needs to be considered in the context of anaerobic verses aerobic ecosystems.     

Supercritical fluid extraction of fish oil from fish by-products: A comparison with other extraction methods

Fish and fish by-products are the main natural source of omega-3 polyunsaturated fatty acids, especially EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), both of them with a great importance in the food and pharmaceutical industries. Comparing to conventional fish oil extraction processes such as cold extraction, wet reduction or enzymatic extraction, supercritical fluid extraction with carbon dioxide under moderate conditions (25 MPa and 313 K) may be useful for reducing fish oil oxidation, especially when fish oil is rich in omega-3 such as salmon oil, and the amount of certain impurities, such as some species of arsenic. Furthermore, taking profit of the advantages of supercritical carbon dioxide as extractive solvent, a coupled extraction-fractionation process is proposed as a way to remove free fatty acids and improve fish oil quality, alternatively to physical and chemical refining procedures.     

Active nano-CuPt3 electrocatalyst supported on graphene for enhancing reactions at the cathode in all-vanadium redox flow batteries

Graphene-supported monometallic (Pt) and bimetallic (CuPt₃) cubic nanocatalysts have been investigated as new positive electrode materials for improving the VO₂⁺/VO²⁺ redox process occurring in the vanadium redox flow batteries (VRB). High-resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM) have been employed to characterize the electrodes. The presence of the CuPt₃ nanocubes on graphene conferred higher electrocatalytic activity due to the much higher electroactive area compared to that obtained with the Pt nanoparticles. The electrochemical surface area of the nano-(CuPt₃)-decorated graphene electrode was 105% higher compared to non-decorated graphene, being then a promising alternative for improving the VRB.     

Novel Monocyclam Derivatives as HIV Entry Inhibitors: Design,Synthesis, Anti‐HIV Evaluation,and Their Interaction with the CXCR4 Co‐receptor

The CXCR4 receptor has been shown to interact with the human immunodeficiency virus (HIV) envelope glycoprotein gp120, leading to fusion of viral and cell membranes. Therefore, ligands that can attach to this receptor represent an important class of therapeutic agents against HIV, thus inhibiting the first step in the cycle of viral infection: the virus–cell entry/fusion. Herein we describe the in silico design, synthesis, and biological evaluation of novel monocyclam derivatives as HIV entry inhibitors. In vitro activity testing of these compounds in cell cultures against HIV strains revealed EC₅₀ values in the low micromolar range without cytotoxicity at the concentrations tested. Docking and molecular dynamics simulations were performed to predict the binding interactions between CXCR4 and the novel monocyclam derivatives. A binding mode of these compounds is proposed which is consistent with the main existing site‐directed mutagenesis data on the CXCR4 co‐receptor. Moreover, molecular modeling comparisons were performed between these novel monocyclams, previously reported non‐cyclam compounds from which the monocyclams are derived, and the well‐known AMD3100 bicyclam CXCR4 inhibitors. Our results suggest that these three structurally diverse CXCR4 inhibitors bind to overlapping but not identical amino acid residues in the transmembrane regions of the receptor.     

Driving factors of the phytoplankton functional groups in a deep Mediterranean reservoir

The control of phytoplankton growth is mainly related to the availability of light and nutrients. Both may select phytoplankton species, but only if they occur in limiting amounts. During the last decade, the functional groups approach, based on the physiological, morphological and ecological attributes of the species, has proved to be a more efficient way to analyze seasonal changes in phytoplankton biomass. We analysed the dynamics of the phytoplankton functional groups sensu Reynolds, recognising the driving forces (light, mixing regime, and nutrients) in the Sau Reservoir, based on a one-year cycle (monthly surface-water sampling). The Sau Reservoir is a Mediterranean water-supply reservoir with a canyon-shaped basin and a clear and mixed epilimnion layer. The long stratification period and high light availability led to high phytoplankton biomass (110.8 fresh-weight mg L⁻¹) in the epilimnion during summer. The reservoir showed P-limitation for phytoplankton growth in this period. All functional groups included one or more species (X2-Rhodomonas spp.; Y-Cryptomonas spp.; F-Oocystis lacustris; K-Aphanocapsa spp.) selected by resources, especially phosphorus. Species of Cryptomonas (group Y) dominated during the mixing period (winter season) in conditions of low light and relatively high availability of dissolved nutrients. Increases in water-column stability during spring stratification led to phytoplankton biomass increases due to the dominance of small flagellate functional groups (X2 and X3, chrysophyceans). The colonial chlorophycean O. lacustris (group F) peaked during the mid-summer stratification, when the mixed epilimnion was clearly depleted in nutrients, especially SRP. High temperature and increases in nutrient concentration during the end-summer and mid-autumn resulted in a decrease of green algae (group F) and increase of Aphanocapsa spp. (cyanobacteria, group K) and dinoflagellates (group L_o). The study also revealed the important role of physical processes in the seasonal gradient, in selecting phytoplankton functional groups, and consequently in the assessment of ecological status. The Q index (assemblage index) based on functional groups indicated the overall good ecological status of the Sau Reservoir, which varied as a function of the mixing regime. This is the first application of the Assemblage Index to a European water-supply reservoir.