Microalgae produce metabolites with notable potentialities to act as reducing and capping agents for the synthesis of silver nanoparticles (AgNPs) in a process widely recognized as an eco-friendly ...and cheaper alternative for the generation of nanoparticles (NPs).
In the present work, AgNPs were synthesized using live
cultures. Two biosynthesis routes were explored: (1) intracellular and (2) extracellular at pH levels of 6-9 using 1-5 mM silver nitrate concentrations.
The generation of NPs was confirmed via ultraviolet-visible spectroscopy. The morphological characteristics were observed using scanning electron microscopy which revealed that the newly developed AgNPs were mostly spherical in sizes starting from 168 nm. The characteristic peaks in a typical Fourier transform infrared spectroscopy suggested that the exopolysaccharides were the possible reducing and capping agents. The antimicrobial spectrum of the newly developed AgNPs was tested against bacterial strains, both Gram-negative, Gram-positive, and yeast, ie,
(American Type Culture Collection ATCC 25922),
(ATCC 27853),
(ATCC 25923), and the yeast
(ATCC 10231), respectively. The antimicrobial activity tests showed a stronger inhibition against Gram-negative bacteria. Statistically, the NPs biosynthesized at pH values of 6 and 8 displayed a higher antimicrobial activity.
Our findings showed that
is capable of generating AgNPs with antimicrobial potential.
Heart diseases are among the most common death causes in the population. Particularly, sudden cardiac death (SCD) is the cause of 10% of the deaths around the world. For this reason, it is necessary ...to develop new methodologies that can predict this event in the earliest possible stage. This work presents a novel methodology to predict when a person can develop an SCD episode before it occurs. It is based on the adroit combination of the empirical mode decomposition, nonlinear measurements, such as the Higuchi fractal and permutation entropy, and a neural network. The obtained results show that the proposed methodology is capable of detecting an SCD episode 25 min before it appears with a 94% accuracy. The main benefits of the proposal are: (1) an improved detection time of 25% compared with previously published works, (2) moderate computational complexity since only two features are used, and (3) it uses the raw ECG without any preprocessing stage, unlike recent previous works.
Abstract The availability of stabilization and sustained delivery systems for antibody therapeutics remains a major clinical challenge, despite the growing development of antibodies for a wide range ...of therapeutic applications due to their specificity and efficacy. A mechanistic understanding of protein-matrix interactions is critical for the development of such systems and is currently lacking as a mode to guide the field. We report mechanistic insight to address this need by using well-defined matrices based on silk gels, in combination with a monoclonal antibody. Variables including antibody loading, matrix density, charge interactions, hydrophobicity and water access were assessed to clarify mechanisms involved in the release of antibody from the biomaterial matrix. The results indicate that antibody release is primarily governed by hydrophobic interactions and hydration resistance, which are controlled by silk matrix chemistry, peptide domain distribution and protein density. Secondary ionic repulsions are also critical in antibody stabilization and release. Matrix modification by free methionine incorporation was found to be an effective strategy for mitigating encapsulation induced antibody oxidation. Additionally, these studies highlight a characterization approach to improve the understanding and development of other protein sustained delivery systems, with broad applicability to the rapidly developing monoclonal antibody field.
Calcium phosphate nanoparticles were doped with zinc ions to produce multifunctional nanomaterials for efficient agronomic fortification and protection of plants. The resulting round-shaped ...nanoparticles (nanoZn) were composed of 20.3 wt % Ca, 14.8 wt % P, and 13.4 wt % Zn and showed a pH-controlled solubility. NanoZn were stable in aqueous solutions at neutral pH but dissolved in citric acid at pH 4.5 (i.e., the pH inside tomato fruits), producing a pH-responsive delivery of the essential nutrients Ca, P, and Zn. In fact, the foliar application of nanoZn on tomato plants provided tomatoes with the highest Zn, Ca, and P contents (causing, respectively, a 65, 65, and 15% increase with respect to a conventional treatment with ZnSO4) and the highest yields. Additionally, nanoZn (100 ppm of Zn) inhibited in vitro the growth of Pseudomonas syringae (Ps), the main cause of bacterial speck, and significantly reduced Ps incidence and mortality in tomato seeds, previously inoculated with the pathogen. Therefore, nanoZn present dual agricultural applicability, enriching crops with nutrients with important metabolic functions in humans and simultaneously protecting the plants against important bacterial-based diseases, with considerable negative impact in crop production.
Energy storage, demand-side response, and electromobility expansion are important issues in the energy transition towards the goal of carbon neutrality. Automobile fleet electrification entails not ...only a reduction in emissions, but also an improvement in energy efficiency. However, the accumulation of batteries in landfills represents a huge problem in the medium-long term. These challenges become more relevant for islands. This article proposes to reuse batteries that are no longer useful for transportation as energy storage to recover renewable energy surpluses. A methodology for the techno-economical assessment of second-life car batteries as a storage solution in wind farms is presented. This method was successfully applied in two wind farms located on Tenerife island. The results delve into the feasibility of the solution, environmental impact, and government policies in terms of subsidy support. Moreover, extending the battery lifespan contributes to the circular economy, which aligns with the United Nations sustainable development goals on affordable and clean energy. In conclusion, second-life batteries could play an essential role as energy storage in the medium-long term on isolated systems.
Display omitted
•Energy storage is essential to recover renewable curtailments in isolated systems.•Second-life batteries from electric vehicles have a great potential as energy storage.•Electricity market prices and battery retrofitting costs reveal as important factors.•Current electricity prices ensure the feasibility of storage after 2027.
River Atoyac is considered to be one of the most polluted rivers in Mexico due to the discharges of untreated or partially treated wastewater from industrial and municipal activities. In order to ...improve the river water quality, it is obligatory to identify the possible contaminant sources for upholding a well-balanced ecosystem. Henceforth, the present study incorporates the application of a continuous real-time monitoring system to identify the provenance of pollutants of the river mainly from anomaly events. Four monitoring stations were installed all along the River Atoyac in the State of Puebla, Central Mexico. The real-time monitoring systems have an ability to measure various water quality parameters for every 15 minutes such as Temperature (T), pH, Conductivity (EC), turbidity (TURB), Dissolved Oxygen (DO), Oxidation Reduction Potential (ORP) and Spectral Absorption Coefficient (SAC). In total, eight water samples of anomaly events (i.e.) 2 per monitoring station during rainy (August–September) and winter seasons (November–December), that were detected using the parameters previously mentioned were procured and also analyzed in the laboratory for evaluating almost 54 physicochemical, inorganic and organic characteristics. Statistical results of factorial analysis explained that 30% of the total variance corresponded to textile effluents, 23% related to discharges produced by automobile and petrochemical industries, and 18% of the total variance defined the agricultural activities. Additionally, indices like Overall Index Pollution, Heavy Metal Evaluation Index, Screening Quick Reference Table and Molecular ratios of hydrocarbons for PAH sources was also calculated to estimate the grade of pollution and associated ecotoxicological risks. The present study also enlightens the fact that the assessed results will definitely provide valuable information for the management of river water quality by developing stringent public policies by governmental agencies for the sustainable conservation of Atoyac River.
Display omitted
•Real time monitoring is regarded to be a fundamental tool for wastewater management.•Identification of pollutant sources is vital to improve river water quality.•River Atoyac is highly impacted by industrial and agricultural effluents.•Pb, Hg and Cd reflect acute toxicity.
► Irrigation requirements were estimated only with midday stem water potential (SWP). ► Physiological measurements were similar in Control and no-water-stress SWP trees. ► Yields and water applied in ...no-water-stress SWP treatment were similar to Control. ► No-water-stress SWP thresholds were valid for different locations during three years.
Irrigation scheduling of fruit trees according to the water balance showed significant differences between locations. In recent years, water status measurements such as leaf water potential have been suggested as irrigation tools in different fruit trees. The aim of this study was to adjust water potential threshold values previously studied and water application approaches that permit the estimation of irrigation requirements of olive trees based on midday stem water potential. The experiments were performed during three seasons (from 2005 to 2007) in two different locations (Badajoz and Ciudad Real) with different weather and cultural conditions. In both locations, the olive orchards were seven years old at the beginning of the experiment but had significantly different canopy development. In Ciudad Real the canopy shaded area at the beginning of the experiment was 15% and the first crop was harvested in 2003. On the other hand, the canopy shaded area of the olive orchard in the Badajoz experiment was 40% and the first crop was harvested in 2001. We therefore considered the Ciudad Real orchard as young and Badajoz as mature. Three different irrigation treatments were compared in both locations: Control treatment with traditional water balance as irrigation scheduling and two treatments in which midday stem water potential (SWP) provided the information about water management. In the midday stem water potential irrigation (WI) treatment the threshold value of SWP was −1.2MPa before the beginning of the massive pit hardening period and −1.4MPa after this date. Finally, in the deficit irrigation (DI) treatment the threshold value of SWP was −2.0MPa throughout the season. In the WI and DI treatments irrigation was applied when SWP reached the threshold value. No significant differences were found between Control and WI in any of the seasons or locations when SWP, leaf conductance, shoot and fruit growth and yield (fruit and oil) were considered. In both locations, the same SWP value in WI treatment resulted in similar water application as the Control treatment. In DI treatment, shoot growth was significantly reduced in both locations in all the seasons. The SWP in DI trees was clearly affected in both locations, while leaf conductance was only reduced in the Badajoz experiment. In the Ciudad Real experiment no significant differences between DI and the other treatments were found in fruit growth, whereas differences were found in Badajoz. However, in Ciudad Real yield in DI treatment was significantly reduced, but not in Badajoz. WI treatment was successful for non-water-stress conditions. On the other hand, DI treatment was a mild water stress treatment which reduced yield only in low covered orchards, but not in the orchards with almost maximum canopy shaded area.
This paper describes the effect of different curing temperatures on the geopolymerization process, physical, mechanical and optical properties of a metakaolin-based geopolymer activated by alkali. ...The influence of different curing temperatures (within the range 30 to 90
°C) was studied systematically by means of differential scanning calorimetry (DSC), SEM, UV/Vis Spectrophotometry, Leaching analysis and Brunauer–Emmet–Teller method (BET). The results showed the existence of an optimum temperature at which the geopolymer presents the best physical and mechanical properties. The geopolymers cured at 30 and 90
°C presented high porosity, and were translucent to the Visible light, which makes possible to tailor this inorganic polymers for optical and photocatalytic applications.
Display omitted
•Determination of activation energies rationalizes the high selectivity to methanol.•Promoting and inhibiting effects of reactants and (by)products are elucidated.•In2O3-x(1 1 1) is ...identified as the main active facet empirically and experimentally.•DFT shows heterolytic H2 splitting and hydride-proton transfer as key for mechanism.•The experimental kinetic parameters are correlated to an ab initio microkinetic model.
Indium oxide has emerged as a highly effective catalyst for methanol synthesis by direct CO2 hydrogenation. Aiming at gathering a deeper fundamental understanding, mechanistic and (micro)kinetic aspects of this catalytic system were investigated. Steady-state evaluation at 5 MPa and variable temperature indicated a lower apparent activation energy for CO2 hydrogenation than for the reverse watergas shift reaction (103 versus 117 kJ mol−1), which is in line with the high methanol selectivity observed. Upon changing the partial pressure of reactants and products, apparent reaction orders of −0.1, 0.5, −0.2, and −0.9 were determined for CO2, H2, methanol, and water, respectively, which highlight a strong inhibition by the latter. Co-feeding of H2O led to catalyst deactivation by sintering for partial pressures exceeding 0.125 MPa, while addition of the byproduct CO to the gas stream could be favorable at a total pressure below 4 MPa but was detrimental at higher pressures. Density Functional Theory simulations conducted on In2O3(1 1 1), which was experimentally and theoretically shown to be the most exposed surface termination, indicated that oxygen vacancies surrounded by three indium atoms enable the activation of CO2 and split hydrogen heterolytically, stabilizing the polarized species formed. The most energetically favored path to methanol comprises three consecutive additions of hydrides and protons and features CH2OOH and CH2(OH)2 as intermediates. Microkinetic modeling based on the DFT results provided values for temperature and concentration-dependent parameters, which are in good agreement with the empirically obtained data. These results are expected to drive further optimization of In2O3-based materials and serve as a solid basis for reactor and process design, thus fostering advances towards a potential large-scale methanol synthesis from CO2.
PDF
