The carboxylate platform is a sustainable and cost-effective way to valorize wastes into biochemicals that replace those of fossil origin. Short-chain fatty acids (SCFAs) are intermediates generated ...during anaerobic fermentation (AF) and are considered high-value-added biochemicals among carboxylates. This investigation aimed to produce SCFAs through the AF of sugar beet molasses at 25 °C and semi-continuous feeding mode in completely stirred tank reactors. A particular focus was devoted to the role of hydraulic retention time (HRT) variation in SCFAs production and distribution profile. The highest SCFAs concentration (44.1 ± 2.3 gCOD/L) was reached at the HRT of 30 days. Caproic acid accounted for 32.5–35.5% (COD-concentration basis) at the long HRTs of 20 and 30 days due to the carbon chain elongation of shorter carboxylic acids. The findings of this study proved that HRT could be used to steer the anaerobic process toward the targeted SCFAs for specific uses. Furthermore, the successful operation at low-temperature conditions (i.e., 25 °C) makes the process economically promising.
The extension of the frozen-density embedding theory for nonvariational methods J. Chem. Theory Comput. 2020, 16, 6880 was utilized to evaluate intermolecular interaction energies for complexes in ...the Zhao–Truhlar basis set. In the applied method (FDET-MP2-FAT-LDA), the same auxiliary system is used to evaluate the correlation energy by means of the second-order Møller–Plesset perturbation theory (MP2), as in our previous work J. Chem. Phys. 2019, 150, 121101. Local density approximation is used for E xcT nadρA,ρB in both cases. Additionally, the contribution to the energy due to the neglected correlation potential was evaluated and analyzed. The domain of applicability of the local density approximation for E xcT nadρA,ρB was determined based on deviations from the interaction energies from the conventional MP2 calculations. The local density approximation for E xcT nadρA,ρB performs well for hydrogen- or dipole-bound complexes. The relative errors in the interaction energy lie within 3–30%. While for charge-transfer complexes, this approximation fails consistently, and for other types of complexes, the performance of this approximation is not systematic. The sources of error are discussed in detail.
Many simulation methods concerning solvated molecules are based on the assumption that the solvated species and the solvent can be characterized by some representative structures of the solute and ...some embedding potential corresponding to this structure. While the averaging of the solvent configurations to obtain an embedding potential has been studied in great detail, this hinges on a single solute structure representation. This assumption is re-examined and generalized for conformationally flexible solutes and tested on 4 nonrigid systems. In this generalized approach, the solute is characterized by a set of representative structures and the corresponding embedding potentials. The representative structures are identified by means of subdividing the statistical ensemble, which in this work is generated by a constant-temperature molecular dynamics simulation. The embedding potential defined in the Frozen-Density Embedding Theory is used to characterize the average effect of the solvent in each subensemble. The numerical examples concern the vertical excitation energies of protonated retinal Schiff bases in protein environments. It is comprehensively shown that subensemble averaging leads to huge computational savings compared with explicit averaging of the excitation energies in the whole ensemble while introducing only minor errors in the case of the systems examined.
•Efficiency of anaerobic digestion is hampered due to microalgae cell wall.•Organic matter solubilisation and improved biodegradability was achieved by all thermal pretreatments.•Thermal ...pretreatments enhanced hydrolysis rate constant and thus faster biogas production.•Carbohydrates solubilised provided a fairly close estimation for methane production.•Best case scenario was achieved by subjecting biomass to 160°C which resulted in 64% methane yield enhancement.
This study investigates the effect of high pressure thermal hydrolysis on organic matter solubilisation and biogas production from Chlorella vulgaris biomass. Microalgae biomass was subjected to three temperatures, namely 140, 160, and 180°C and two heating times (10 and 20min). Results showed that carbohydrates release prevailed over proteins. Carbohydrates were solubilised concomitantly with increasing temperatures. According to the infrared spectra and monomeric sugars determined in the pretreated medium, temperatures applied clearly affected the solubilisation of structural carbohydrates of the microalgae cell wall. Likewise, thermal pretreatment provided enhanced methane production with regard to the raw algal biomass. Enhanced hydrolysis rate constant supported faster biogas production. Regardless the heating time employed, increasing temperatures depicted increasing methane production. Even thought, organic matter solubilisation was greater at 180°C, the anaerobic biodegradability did not show the same trend. This fact was ascribed to the formation of reaction products that hampered methane production. Best case scenario was achieved by subjecting biomass to 160°C which resulted in 64% methane yield enhancement.
Biogas generation is the least complex technology to transform microalgae biomass into bioenergy. Since hydrolysis has been pointed out as the rate limiting stage of anaerobic digestion, the main ...challenge for an efficient biogas production is the optimization of cell wall disruption/hydrolysis. Among all tested pretreatments, enzymatic treatments were demonstrated not only very effective in disruption/hydrolysis but they also revealed the impact of microalgae macromolecular composition in the anaerobic process. Although carbohydrates have been traditionally recognized as the polymers responsible for the low microalgae digestibility, protease addition resulted in the highest organic matter solubilization and the highest methane production. However, protein solubilization during the pretreatment can result in anaerobic digestion inhibition due to the release of large amounts of ammonium nitrogen. The possible solutions to overcome these negative effects include the reduction of protein biomass levels by culturing the microalgae in low nitrogen media and the use of ammonia tolerant anaerobic inocula. Overall, this review is intended to evidence the relevance of microalgae proteins in different stages of anaerobic digestion, namely hydrolysis and methanogenesis.
Metabolic rare diseases present a serious clinical manifestation causing several problems such as mental retardation, liver damage, hepatocarcinoma and even death without a diagnosis in the first ...days of life. Additionally, there is not any final treatment for these diseases but a dietary restriction, so patients have to control their biomarkers level during their whole life. Current methods for diagnosis and monitoring are tedious, very time-consuming, not portable and need high amount of sample, so they are not suitable for a point-of-care (POC) application. In this sense, electrochemistry presents the required characteristics to be used as POC for metabolic rare diseases. Specifically, this review explores the current methods for amino acids and carbohydrates sensing as biomarkers of metabolic rare diseases using electrochemical (bio)-sensing approaches, especially those based on nanomaterials in both, off and on-chip detection, as well as their suitability in metabolic rare diseases diagnosis and monitoring using clinical samples.
•Nanomaterial-based electrochemical (bio)-sensing for rare diseases diagnostics.•Smart diagnostic tools based exclusively on nanomaterials.•Electrochemical-based POC for metabolic rare diseases diagnosis and monitoring.
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•Strawberry methanolic extract was rich in phenolic compounds and minerals.•Treatments significantly delayed amyloid β-protein induced paralysis in CL4176.•The extract reduced ...oxidative stress induced by AAPH in the wild strain.•Effects were mediated by DAF-16 and SKN-1 pathway signaling.•Strawberry could be an excellent ingredient to be used for functional food.
Bioactive compounds from strawberries have been associated with multiple healthy benefits. The present study aimed to assess chemical characterization of a methanolic extract of the Romina strawberry variety in terms of antioxidant capacity, polyphenols profile and chemical elements content. Additionally, potential toxicity, the effect on amyloid-β production and oxidative stress of the extract was in vivo evaluated in the experimental model Caenorhabditis elegans. Results revealed an important content in phenolic compounds (mainly ellagic acid and pelargonidin-3-glucoside) and minerals (K, Mg, P and Ca). The treatment with 100, 500 or 1000 μg/mL of strawberry extract did not show toxicity. On the contrary, the extract was able to delay amyloid β-protein induced paralysis, reduced amyloid-β aggregation and prevented oxidative stress. The potential molecular mechanisms present behind the observed results explored by RNAi technology revealed that DAF-16/FOXO and SKN-1/NRF2 signaling pathways were, at least partially, involved.
•Nanoparticles and antioxidants: chemistry for assessing antioxidant capacity.•Synthesis of nanoparticles for evaluating total antioxidant capacity.•Chemistry on nanoparticles for selective detection ...of target antioxidants.
The current review describes the creative use of metallic nanoparticles (mostly gold and silver) and quantum dots as novel tools for reliable assessment of antioxidant activity in food and biological samples. Since evaluation of antioxidant capacity is a complex issue, these nanomaterials emerge as novel, simple and inexpensive tools in the field, becoming not only a valuable alternative to classical approaches but also a complementary one.
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