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We describe biomimetic adhesives inspired by the marine glues fabricated by the sandcastle worm. The formation of stable polyelectrolyte complexes between poly-L-lysine (PLL) and ...glycosaminoglycans (GAGs) with different sulfation degree – heparin (HEP), chondroitin sulfate (CS) and hyaluronic acid (HA) – is optimized by zeta-potential titrations. These PLL/GAG complexes are transformed into compact polyelectrolyte complexes (coPECs) with controlled water contents and densities via baroplastic processing. Rotational shear tests demonstrate that coPECs containing sulfated GAGs (HEP or CS) have solid-like properties, whereas HA-based complexes form highly hydrated viscous-like networks. The adhesiveness of the generated coPECs (normalized lap shear strength) is tested in dry and wet states using polystyrene and rabbit skin, respectively. In dry state, the adhesives exhibit lap shear strengths in the order of hundreds of kPa, with coPLL/HEP and coPLL/CS being about 1.5 times stronger than coPLL/HA. In wet state, all coPECs seal rabbit skin and recover over 60% of the elongation capacity of intact skin with coPLL/HA providing the sturdiest adhesion (∼85% elongation recovery). We demonstrate that this is due to the higher water fraction that improves the bonding between the wet specimens, showcasing the potential superior mechanical recovery on injured tissues.
The development of medical sealants with sufficient adhesive strength in the presence of water and moist remains a huge challenge. We present glycosaminoglycans (GAGs) as biomaterials for the assembly of baroplastics with strong adhesive strength to soft tissues at physiological conditions. Baroplastics with tacky properties were generated by a mild assembly process based on polyelectrolyte complexation and compaction. These materials behave as versatile sealants: their adhesiveness can be adjusted to either dry or wet specimens because of the different sulfation degree of GAGs. These sealants were noncytotoxic towards L929 cells and allowed the damaged skin to recover a great deal of its native elasticity: they preserved the J-shaped stress/strain mechanical response that is typical of biological soft tissues.
The current study has proved the technical feasibility of including electrochemical advanced oxidation processes (EAOPs) in a multistage strategy for the remediation of a sanitary landfill leachate ...that embraced: (i) first biological treatment to remove the biodegradable organic fraction, oxidize ammonium and reduce alkalinity, (ii) coagulation of the bio-treated leachate to precipitate humic acids and particles, followed by separation of the clarified effluent, and (iii) oxidation of the resulting effluent by an EAOP to degrade the recalcitrant organic matter and increase its biodegradability so that a second biological process for removal of biodegradable organics and nitrogen content could be applied. The influence of current density on an UVA photoelectro-Fenton (PEF) process was firstly assessed. The oxidation ability of various EAOPs such as electro-Fenton (EF) with two distinct initial total dissolved iron concentrations (TDI0), PEF and solar PEF (SPEF) was further evaluated and these processes were compared with their analogous chemical ones. A detailed assessment of the two first treatment stages was made and the biodegradability enhancement during the SPEF process was determined by a Zahn–Wellens test to define the ideal organics oxidation state to stop the EAOP and apply the second biological treatment. The best current density was 200 mA cm−2 for a PEF process using a BDD anode, TDI0 of 60 mg L−1, pH 2.8 and 20 °C. The relative oxidation ability of EAOPs increased in the order EF with 12 mg TDI0 L−1 < EF with 60 mg TDI0 L−1 < PEF with 60 mg TDI0 L−1 ≤ SPEF with 60 mg TDI0 L−1, using the abovementioned conditions. While EF process was much superior to the Fenton one, the superiority of PEF over photo-Fenton was less evident and SPEF attained similar degradation to solar photo-Fenton. To provide a final dissolved organic carbon (DOC) of 163 mg L−1 to fulfill the discharge limits into the environment after a second biological process, 6.2 kJ L−1 UV energy and 36 kWh m−3 electrical energy were consumed using SPEF with a BDD anode at 200 mA cm−2, 60 mg TDI0 L−1, pH 2.8 and 20 °C.
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•First study of EAOPs with H2O2 electrogeneration for landfill leachate treatment.•Multistage treatment strategy: bio-process/coagulation/EAOP/bio-process.•EAOPs used for recalcitrant organics degradation and biodegradability enhancement.•Efficiency of EAOPs in the order EF < PEF ≤ SPEF.•Consumption of 6.2 kJ L−1 UV energy and 36 kWh m−3 electrical energy using SPEF.
Extensive research has been conducted on biomimetic interfaces mimicking the complex and diverse microenvironment of cell membranes to gain insights into bioactive compound interactions and membrane ...biophysics modulation. The present study proposes an innovative approach that combines five prospective label‐free methodologies (derivative spectroscopy, synchrotron small‐ and wide‐angle X‐Ray scattering, attenuated total reflection–Fourier‐transform infrared spectroscopy, quartz‐crystal microbalance with dissipation, and surface plasmon resonance) to showcase their synergistic capabilities and complementarity in investigating drug–membrane interactions. This multitechnique approach combines the real‐time monitoring of the adsorption process under continuous flow conditions with the steady‐state perspective of this process. As a proof of concept, the interaction of three bioactive compounds (caffeine, testosterone, and diclofenac) with two biomimetic membrane interfaces (multistacked lipid bilayers and supported lipid bilayers) mimicking the more ordered lipid transient phases, with and without cholesterol (lo and so), that are responsible for a variety of membrane‐associated biological activities, is investigated. The biophysical effects of the bioactives are discussed using complementary data from real‐time and steady‐state experiments, including membrane adsorption and distribution, predicted location, and induced changes in order and fluidity, encompassing bilayer thickness, hydration, and area per lipid molecule.
This work introduces a label‐free multitechnique approach to explore the biophysics underlying the interactions between bioactives and biomimetic models of the often‐overlooked solid‐ and liquid‐ordered phases. The combination of real‐time continuous flow with equilibrium steadystate techniques was successful in providing comprehensive molecular insight into drug‐membrane interactions while overcoming the limitations of conventional fluorescence‐based techniques.
The regeneration of soft biological tissues requires new substitutes that exhibit mechanical properties similar to the native tissue. Herein, thin saloplastic membranes with tunable physical ...properties are prepared by complexation of chitosan and alginate solutions containing different concentrations of sodium chloride. Polyelectrolyte complexes (PECs) are transferred to flat Petri dishes for compaction into membrane shapes by sedimentation and solvent evaporation. All membranes are resistant to degradation by lysozyme and are stable in solutions with pH values between 1 and 13. Immersing the different membranes in new doping solutions of increasing salt concentrations triggers the typical saloplastic behavior, with a high water absorption and decrease of the rigidity and ultimate tensile strength. The range of such variations is tuned by the sodium chloride amount used in the synthesis: high salt concentrations increase water uptake and tensile moduli, while decreasing the ultimate strength. Cellular assays demonstrate high proliferation rates and viability of L929 fibroblasts seeded onto the most rigid membranes. The results validate the use of saloplastic membranes as soft tissue substitutes for future biomedical applications.
The red-billed leiothrix (
Leiothrix lutea
) is an Asian-native passerine which has been introduced across several regions of the world, including Europe. Although it is widely considered to be among ...the most harmful bird invaders, its occurrence in Europe is still understudied. Here, we aim to assess its distribution and population status in Europe. We obtained records for ten countries distributed throughout 37 spatially independent regions. The species is already established in France, Italy, Spain, and Portugal. The distribution range in Europe almost doubled between the periods of 2000–2008 and 2009–2017. A species distribution model showed that leiothrix presence probability increases with increasing combined values of human population density, spatial trend of occurrences, minimum temperature of the coldest month, precipitation of the driest quarter and precipitation seasonality. We identified two main introduction periods: late nineteenth and late twentieth centuries. In 1997, the species trade started to be regulated, resulting in a reduction of the imported numbers during the following years. Thus, the recent increase of the distribution range may be mostly related with self-dispersion. There has apparently been a great introduction rate near large urban areas which resulted in a broad spread into adjacent forests. The relationship between climatic traits and leiothrix presence may be due to its feeding ecology, as it often forages in wet soil and is limited by the availability of fruits and invertebrates. Future climate change scenarios can add further uncertainty to the invasion process by the leiothrix in Europe.
This paper compares the service quality between 4G and 5G New Radio (NR) among different sub-6 GHz frequency bands in an urban micro-cellular outdoor setting. An updated version of LTE-Sim is ...considered to obtain the exponential effective signal-to-interference-plus-noise ratio in 4G while determining the modulation and coding scheme. System capacity is obtained by considering a video application at 3.1 Mb/s and the proportional fair (PF) scheduler while comparing 4G and 5G NR through system-level simulations (the 5G-air-simulator is considered for 5G NR). The modified largest weighted delay first (M-LWDF) scheduler is compared with the PF, though only in 4G. Optimal system performance is reached both in 4G and 5G NR for cell radii longer than two times the breakpoint distance (or beyond), which are preferable compared to the shortest values for the cell radius. We have learned that the packet loss ratio (PLR) is higher for the cell radii, R, shorter than breakpoint distance, <inline-formula> <tex-math notation="LaTeX">d'_{BP} </tex-math></inline-formula>. For <inline-formula> <tex-math notation="LaTeX">d'_{BP} \leq R \leq 1000 </tex-math></inline-formula> m, the PLR first decreases and then increases. For a target PLR < 2%, in 4G, the highest maximum average goodput is obtained with the M-LWDF scheduler (10-25% increase). This maximum occurs at the 2.6 GHz and 3.5 GHz frequency bands for <inline-formula> <tex-math notation="LaTeX">300\leq R \leq 500 </tex-math></inline-formula> m, while at 5.62 GHz the highest goodput occurs for the longest Rs. With 5G NR and the PF, the maximum average goodput increases, in our simulations, from <inline-formula> <tex-math notation="LaTeX">\approx ~14.1 </tex-math></inline-formula> (in 4G) to 26.1 Mb/s (20 MHz bandwidth).
This paper proposes a model capable of predicting fatal occurrences in aviation events such as accidents and incidents, using as inputs the human factors that contributed to each incident, together ...with information about the flight. This is important because aviation demands have increased over the years; while safety standards are very rigorous, managing risk and preventing failures due to human factors, thereby further increasing safety, requires models capable of predicting potential failures or risky situations. The database for this paper’s model was provided by the Aviation Safety Network (ASN). Correlations between leading causes of incident and the human element are proposed, using the Human Factors Analysis Classification System (HFACS). A classification model system is proposed, with the database preprocessed for the use of machine learning techniques. For modeling, two supervised learning algorithms, Random Forest (RF) and Artificial Neural Networks (ANN), and the semi-supervised Active Learning (AL) are considered. Their respective structures are optimized applying hyperparameter analysis to improve the model. The best predictive model, obtained with RF, was able to achieve an accuracy of 90%, macro F1 of 87%, and a recall of 86%, outperforming ANN models, with a lower ability to predict fatal accidents. These performances are expected to assist decision makers in planning actions to avoid human factors that may cause aviation incidents, and to direct efforts to the more important areas.
The construction of multilayered films with tunable properties could offer new routes to produce biomaterials as a platform for 3D cell cultivation. In this study, multilayered films produced with ...five bilayers of chitosan and alginate (CHT/ALG) were built using water-soluble modified mesyl and tosyl⁻CHT via layer-by-layer (LbL) self-assembly. NMR results demonstrated the presences of mesyl (2.83 ppm) and tosyl groups (2.39, 7.37 and 7.70 ppm) in the chemical structure of modified chitosans. The buildup of multilayered films was monitored by quartz-crystal-microbalance (QCM-D) and film thickness was estimated using the Voigt-based viscoelastic model. QCM-D results demonstrated that CHT/ALG films constructed using mesyl or tosyl modifications (mCHT/ALG) were significantly thinner in comparison to the CHT/ALG films constructed with unmodified chitosan (
< 0.05). Adhesion analysis demonstrated that human adipose stem cells (hASCs) did not adhere to the mCHT/ALG multilayered films and formed aggregates with sizes between ca. 100⁻200 µm. In vitro studies on cell metabolic activity and live/dead staining suggested that mCHT/ALG multilayered films are nontoxic toward hACSs. Multilayered films produced via LbL assembly of ALG and off-the-shelf, water-soluble modified chitosans could be used as a scaffold for the 3D aggregates formation of hASCs in vitro.
A multistage treatment system, at a scale close to the industrial, was designed for the treatment of a mature raw landfill leachate, including: a) an activated sludge biological oxidation (ASBO), ...under aerobic and anoxic conditions; b) a solar photo-Fenton process, enhancing the bio-treated leachate biodegradability, with and without sludge removal after acidification; and c) a final polishing step, with further ASBO.
The raw leachate was characterized by a high concentration of humic substances (HS) (1211 mg CHS/L), representing 39% of the dissolved organic carbon (DOC) content, and a high nitrogen content, mainly in the form of ammonium nitrogen (>3.8 g NH4+–N/L).
In the first biological oxidation step, a 95% removal of total nitrogen and a 39% mineralization in terms of DOC were achieved, remaining only the recalcitrant fraction, mainly attributed to HS (57% of DOC). Under aerobic conditions, the highest nitrification rate obtained was 8.2 mg NH4+–N/h/g of volatile suspended solids (VSS), and under anoxic conditions, the maximum denitrification rate obtained was 5.8 mg (NO2−–N + NO3−–N)/h/g VSS, with a C/N consumption ratio of 2.4 mg CH3OH/mg (NO2−–N + NO3−–N).
The precipitation of humic acids (37% of HS) after acidification of the bio-treated leachate corresponds to a 96% DOC abatement. The amount of UV energy and H2O2 consumption during the photo-Fenton reaction was 30% higher in the experiment without sludge removal and, consequently, the reaction velocity was 30% lower. The phototreatment process led to the depletion of HS >80%, of low-molecular-weight carboxylate anions >70% and other organic micropollutants, thus resulting in a total biodegradability increase of >70%.
The second biological oxidation allowed to obtain a final treated leachate in compliance with legal discharge limits regarding water bodies (with the exception of sulfate ions), considering the experiment without sludge.
Finally, the high efficiency of the overall treatment process was further reinforced by the total removal percentages attained for the identified organic trace contaminants (>90%).
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•Multistage treatment system for stabilized raw leachate from sanitary landfill.•Integration of biological/chemical/biological oxidations processes.•Nitrogen removal using biological nitrification and denitrification reactions.•The photo-oxidation led to the depletion of HS and other organic micropollutants.•Organic trace contaminants identification and evolution profile follow-up.
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