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Agostini, C. A., Guzman, A. M., Nasirov, S., & Silva, C. (2019). A surplus based framework for cross-border electricity trade in South America. Energy Policy, 128, 673–684.
Abstract: The South American region has experienced a steady increase in its demand for electricity and faces several challenges in the development of the electricity sector. Among them, high fluctuations in hydro generation, high and volatile prices of fossil fuels, and environmental and social impacts associated to energy activities. Strengthening cooperation for cross-border electricity trade is considered a sustainable alternative for addressing these challenges. For the expansion of electricity trade among countries within the region, both infrastructure and a regulation that defines the conditions of the electric power exchanges between countries are required. A good regulatory framework would allow all market players to have access to the commercialization of energy with other countries in the region, guarantee that the treatment of exchanges is non-discriminatory, and maintain the efficiency, cost effectiveness and security characteristics operation of all electricity systems. In this context, this paper proposes a framework with the basic setting conditions for the import and export of energy from the “surplus” available for exchange. The empirical analysis of the regulatory proposal, based on simulations, shows that the exchange of energy from Chile with its neighboring countries is feasible in a clear and transparent manner, reducing the marginal costs of energy and the total cost of operation, keeping the average cost of generation relatively constant.
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Alejo, L., Atkinson, J., & Lackner, S. (2020). Looking deeper – exploring hidden patterns in reactor data of N-removal systems through clustering analysis. Water Sci. Technol., 81(8), 1569–1577.
Abstract: In this work, clustering analysis of two partial nitritation-anammox (PN-A) moving bed biofilm reactors (MBBR) containing different types of carrier material was explored for the identification of patterns and operational conditions that may benefit process performance. The systems ran for two years under fluctuations of temperature and organic matter. Ex situ batch activity tests were performed every other week during the operation of these reactors. These datasets and the parameters, which were monitored online and in the laboratory, were combined and analyzed applying clustering analysis to identify non-obvious information regarding the performance of the systems. The initial results were consistent with the literature and from an operational perspective, which allowed the parameters to be explored further. The new information revealed that the oxidation reduction potential (ORP) and the anaerobic ammonium oxidizing bacteria (AnAOB) activity correlated well. ORP also dropped when the reactors were exposed to real wastewater (presence of organic matter). Moreover, operating conditions during nitrite accumulation were identified through clustering, and also revealed inhibition of anammox bacteria already at low nitrite concentrations.
Keywords: clustering; feature selection; k-means; partial nitritation-anammox
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Alvarez-Miranda, E., Campos-Valdes, C., Quiroga, M. M., Moreno-Faguett, M., & Pereira, J. (2020). A Multi-Criteria Pen for Drawing Fair Districts: When Democratic and Demographic Fairness Matter. Mathematics, 8(9), 27 pp.
Abstract: Electoral systems are modified by individuals who have incentives to bias the rules for their political advantage (i.e., gerrymandering). To prevent gerrymandering, legislative institutions can rely on mathematical tools to guarantee democratic fairness and territorial contiguity. These tools have been successfully used in the past; however, there is a need to accommodate additional meanings of the term fairness within the electoral systems of modern democracies. In this paper, we present an optimization framework that considers multiple criteria for drawing districts and assigning the number of representatives. Besides some typical districting criteria (malapportionment and contiguity), we introduce novel criteria for ensuring territorial equilibrium and incentives for candidates to deploy their representation efforts fairly during their campaign and period in office. We test the method, which we denote as Multi-criteria Pen, in a recent and a forthcoming reform of the Chilean electoral system. The results show the potential of our tool to improve the current territorial design and offers insights on the motivations, objectives, and deficiencies of both reform plans.
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Araneda, A., Sanhueza, V., & Bennun, L. (2016). Simplified Calibration for Total-Reflection X-ray Fluorescence. Anal. Lett., 49(11), 1711–1721.
Abstract: The usual method to determine the relative sensitivity curve for total-reflection X-ray fluorescence (TXRF) uses multielemental solutions, which may be purchased or prepared in the laboratory. In the former case, the accuracy and precision of the concentrations are certified by the provider, while in the latter, the experience of the technical staff determines the analytical quality. These procedures are costly and the quality of the solutions cannot be easily verified. The goal of this work was to use pure crystalline salts containing two elements that may be quantified by TXRF for the calibration of the spectrometer. The analysis of these samples along with a mathematical procedure assures good precision of the results. The reported method is economically efficient, simple, and eliminates the uncertainties of the element concentration in the samples produced by the standard methods, thereby improving the quality of TXRF results.
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Asenjo, F. A., & Hojman, S. A. (2017). Do electromagnetic waves always propagate along null geodesics? Class. Quantum Gravity, 34(20), 12 pp.
Abstract: We find exact solutions to Maxwell equations written in terms of fourvector potentials in non-rotating, as well as in Gdel and Kerr spacetimes. We show that Maxwell equations can be reduced to two uncoupled secondorder differential equations for combinations of the components of the four-vector potential. Exact electromagnetic waves solutions are written on given gravitational field backgrounds where they evolve. We find that in non-rotating spherical symmetric spacetimes, electromagnetic waves travel along null geodesics. However, electromagnetic waves on Gdel and Kerr spacetimes do not exhibit that behavior.
Keywords: electromagnetic waves; curved spacetime; non-null geodesics
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Asenjo, F. A., & Hojman, S. A. (2021). Reply to Comment on 'Do electromagnetic waves always propagate along null geodesics?' Reply. Class. Quantum Gravity, 38(23), 238002.
Abstract: A reply to the previous article commenting on non-geodesical propagation of electromagnetic fields on gravitational backgrounds and the eikonal limit are presented.
Keywords: couplings; electromagnetic wave; propagation; consistency; geometrical; eikonal limit
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Aylwin, R., Jerez-Hanckes, C., Schwab, C., & Zech, J. (2020). Domain Uncertainty Quantification in Computational Electromagnetics. SIAM-ASA J. Uncertain. Quantif., 8(1), 301–341.
Abstract: We study the numerical approximation of time-harmonic, electromagnetic fields inside a lossy cavity of uncertain geometry. Key assumptions are a possibly high-dimensional parametrization of the uncertain geometry along with a suitable transformation to a fixed, nominal domain. This uncertainty parametrization results in families of countably parametric, Maxwell-like cavity problems that are posed in a single domain, with inhomogeneous coefficients that possess finite, possibly low spatial regularity, but exhibit holomorphic parametric dependence in the differential operator. Our computational scheme is composed of a sparse grid interpolation in the high-dimensional parameter domain and an Hcurl -conforming edge element discretization of the parametric problem in the nominal domain. As a stepping-stone in the analysis, we derive a novel Strang-type lemma for Maxwell-like problems in the nominal domain, which is of independent interest. Moreover, we accommodate arbitrary small Sobolev regularity of the electric field and also cover uncertain isotropic constitutive or material laws. The shape holomorphy and edge-element consistency error analysis for the nominal problem are shown to imply convergence rates for multilevel Monte Carlo and for quasi-Monte Carlo integration, as well as sparse grid approximations, in uncertainty quantification for computational electromagnetics. They also imply expression rate estimates for deep ReLU networks of shape-to-solution maps in this setting. Finally, our computational experiments confirm the presented theoretical results.
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Beya-Marshall, V., Arcos, E., Seguel, O., Galleguillos, M., & Kremer, C. (2022). Optimal irrigation management for avocado (cv. 'Hass') trees by monitoring soil water content and plant water status. Agric. Water Manag., 271, 107794.
Abstract: Irrigation scheduling based on soil water content (Ow) sensors requires that Ow be maintained within a range (management lines) that is optimal for plant growth. The lower limit or “breaking point ” is determined following the soil water content dynamics on the transition of a rapid rate of depletion to a slower, under similar reference evapotranspiration. Although this criterion is practical, its implementation should be validated with plant water status measurement that contemplate weather condition, such as stem water potential “non-stressed ” baseline (Tx as a function of vapor-pressure deficit (VPD) in Ow conditions that do not limit yield). A study was con-ducted on a mature cv. 'Hass' avocado orchard in Central Chile during two seasons. There were 5 irrigation treatments: T1, Control; T2 and T3 with 29% less and 25% more of what was applied in T1, respectively; T4 and T5 same as Control until first and second fruit drop abscission, respectively, and then with 29% less. T1 trees were irrigated using a continuous frequency domain reflectometry (FDR) probe to maintain the root zone be-tween field capacity and the breaking point. There was biweekly monitoring of the Ow prior to irrigation, Tx and VPD. The Tx decline proportional to the intensity and the timing of water restriction; however, no treatment affected the crop load in either season. T2 did not show significant detrimental in fruit size, production and maturation, despite that frequently reached water content levels at the limit of the breaking point, and showed lower levels of stem water potential than Control, being the treatment with the highest water productivity. The results confirm that breaking point is an effective criterion to establish irrigation management. Additionally, when comparing the baseline for our non-stressed trees with a baseline from full irrigation treatments obtained from the literature, 30% water savings were achieved.
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Caceres, C., Moczko, E., Basozabal, I., Guerreiro, A., & Piletsky, S. (2021). Molecularly Imprinted Nanoparticles (NanoMIPs) Selective for Proteins: Optimization of a Protocol for Solid-Phase Synthesis Using Automatic Chemical Reactor. Polymers, 13(3), 314.
Abstract: Molecularly imprinted polymer nanoparticles (nanoMIPs) are receiving broad interest as robust and highly selective synthetic receptors for a variety of molecules. Due to their stability, inexpensive synthesis and easy implementation, they are considered a promising alternative to antibodies in sensors, diagnostics and separation applications. The most challenging targets for the production of synthetic receptors are proteins due to their fragile nature and the multitude of possible binding sites in their structure. Herein, we describe the modification and optimization of the protocol for synthesis of nanoMIPs with specificity for proteins using the prototype of an automated solid-phase synthesizer. Using an automated system gives an advantage for the simple, fast and fully controlled, reproducible production of nanoMIPs. The molecular imprinting in the reactor is performed using a template covalently immobilized on a solid support, in mild conditions suitable for preserving protein native structure. The validation of the protocol was made by assessing the ability to regenerate a solid-phase, and by measuring affinity and specificity of nanoparticles. As a model protein, we have chosen trypsin since its enzymatic activity can be easily monitored by using a commercial colorimetric assay. Different protocols were tested for their ability to improve the yield of high affinity nanoparticles in the final elution.
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Caceres, C., Morgado, M. D. G., Bozo, F. C., Piletsky, S., & Moczko, E. (2022). Rapid Selective Detection and Quantification of beta-Blockers Used in Doping Based on Molecularly Imprinted Nanoparticles (NanoMIPs). Polymers, 14(24), 5420.
Abstract: Human performance enhancing drugs (PEDs), frequently used in sport competitions, are strictly prohibited by the World Anti-Doping Agency (WADA). Biological samples collected from ath-letes and regular patients are continuously tested regarding the identification and/or quantification of the banned substances. Current work is focused on the application of a new analytical method, molecularly imprinted nanoparticles (nanoMIPs), to detect and determine concentrations of certain prohibited drugs, such as B-blockers, in water and human urine samples. These medications are used in the treatment of cardiovascular conditions, negative effects of adrenaline (helping to relief stress), and hypertension (slowing down the pulse and softening the arteries). They can also significantly increase muscle relaxation and improve heart efficiency. The new method of the detection and quantification of B-blockers is based on synthesis, characterization, and implementation of nanoMIPs (so-called plastic antibodies). It offers numerous advantages over the traditional methods, including high binding capacity, affinity, and selectivity for target molecules. Additionally, the whole process is less complicated, cheaper, and better controlled. The size and shape of the nanoMIPs is evaluated by dynamic light scattering (DLS) and transmission electron microscope (TEM). The affinity and selectivity of the nanoparticles are investigated by competitive pseudo enzyme-linked immunosorbent assay (pseudo-ELISA) similar to common immunoassays employing natural antibodies. To provide reliable results towards either doping detection or therapeutic monitoring using the minimal invasive method, the qualitative and quantitative analysis of these drugs is performed in water and human urine samples. It is demonstrated that the assay can detect B-blockers in water within the linear range 1 nmolmiddotL(-1)-1 mmolmiddotL(-1) for atenolol with the detection limit 50.6 ng mL(-1), and the linear range 1 mmolmiddotL(-1)-10 mmolmiddotL(-1) for labetalol with the detection limit of 90.5 ngmiddotmL(-1). In human urine samples, the linear range is recorded in the concentration range 0.1 mmolmiddotL(-1)-10 nmolmiddotL(-1) for atenolol and 1 mmolmiddotL(-1)-10 nmolmiddotL(-1) for labetalol with a detection limit of 61.0 ngmiddotmL(-1)for atenolol and 99.4 ngmiddotmL(-1) for labetalol.
Keywords: doping in sports; performance enhancing drugs (PEDs); beta-blockers; atenolol; labetalol; molecularly imprinting nanoparticles (nanoMIPs); enzyme-linked immunosorbent assay (ELISA); “pseudo” enzyme-linked immunosorbent assay (pseudo-ELISA); dynamic analysis light scattering (DLS); transmission electron microscope (TEM)
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Campos-Valdes, C., Alvarez-Miranda, E., Quiroga, M. M., Pereira, J., & Duran, F. L. (2021). The Impact of Candidates' Profile and Campaign Decisions in Electoral Results: A Data Analytics Approach. Mathematics, 9(8), 902.
Abstract: In recent years, a wide range of techniques has been developed to predict electoral results and to measure the influence of different factors in these results. In this paper, we analyze the influence of the political profile of candidates (characterized by personal and political features) and their campaign effort (characterized by electoral expenditure and by territorial deployment strategies retrieved from social networks activity) on the electoral results. This analysis is carried out by using three of the most frequent data analyitcs algorithms in the literature. For our analysis, we consider the 2017 Parliamentary elections in Chile, which are the first elections after a major reform of the electoral system, that encompassed a transition from a binomial to a proportional system, a modification of the districts' structure, an increase in the number of seats, and the requirement of gender parity in the lists of the different coalitions. The obtained results reveal that, regardless of the political coalition, the electoral experience of candidates, in particular in the same seat they are running for (even when the corresponding district is modified), is by large the most influential factor to explain the electoral results. However, the attained results show that the influence of other features, such as campaign expenditures, depends on the political coalition. Additionally, by means of a simulation procedure, we show how different levels of territorial deployment efforts might impact on the results of candidates. This procedure could be used by parties and coalitions when planning their campaign strategies.
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Cardenas, C., Guzman, F., Carmona, M., Munoz, C., Nilo, L., Labra, A., et al. (2020). Synthetic Peptides as a Promising Alternative to Control Viral Infections in Atlantic Salmon. Pathogens, 9(8), 600.
Abstract: Viral infections in salmonids represent an ongoing challenge for the aquaculture industry. Two RNA viruses, the infectious pancreatic necrosis virus (IPNV) and the infectious salmon anemia virus (ISAV), have become a latent risk without healing therapies available for either. In this context, antiviral peptides emerge as effective and relatively safe therapeutic molecules. Based on in silico analysis of VP2 protein from IPNV and the RNA-dependent RNA polymerase from ISAV, a set of peptides was designed and were chemically synthesized to block selected key events in their corresponding infectivity processes. The peptides were tested in fish cell lines in vitro, and four were selected for decreasing the viral load: peptide GIM182 for IPNV, and peptides GIM535, GIM538 and GIM539 for ISAV. In vivo tests with the IPNV GIM 182 peptide were carried out using Salmo salar fish, showing a significant decrease of viral load, and proving the safety of the peptide for fish. The results indicate that the use of peptides as antiviral agents in disease control might be a viable alternative to explore in aquaculture.`
Keywords: interfering peptides; viral treatment; RNA fish virusesViral infections in salmonids represent an ongoing challenge for the aquaculture industry. Two RNA viruses, the infectious pancreatic necrosis virus (IPNV) and the infectious salmon anemia virus (ISAV), have become a latent risk without healing therapies available for either. In this context, antiviral peptides emerge as effective and relatively safe therapeutic molecules. Based on in silico analysis of VP2 protein from IPNV and the RNA-dependent RNA polymerase from ISAV, a set of peptides was designed and were chemically synthesized to block selected key events in their corresponding infectivity processes. The peptides were tested in fish cell lines in vitro, and four were selected for decreasing the viral load: peptide GIM182 for IPNV, and peptides GIM535, GIM538 and GIM539 for ISAV. In vivo tests with the IPNV GIM 182 peptide were carried out using Salmo salar fish, showing a significant decrease of viral load, and proving the safety of the peptide for fish. The results indicate that the use of peptides as antiviral agents in disease control might be a viable alternative to explore in aquaculture.
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Carrasco, M., Alvarez, F., Velazquez, R., Concha, J., & Perez-Cotapos, F. (2019). Brush-Holder Integrated Load Sensor Prototype for SAG Grinding Mill Motor. Electronics, 8(11), 14 pp.
Abstract: One of the most widely used electro-mechanical systems in large-scale mining is the electric motor. This device is employed in practically every phase of production. For this reason, it needs to be inspected regularly to maintain maximum operability, thus avoiding unplanned stoppages. In order to identify potential faults, regular check-ups are performed to measure the internal parameters of the components, especially the brushes and brush-holders. Both components must be properly aligned and calibrated to avoid electric arcs to the internal insulation of the motor. Although there is an increasing effort to improve inspection tasks, most inspection procedures are manual, leading to unnecessary costs in inspection time, errors in data entry, and, in extreme cases, measurement errors. This research presents the design, development, and assessment of an integrated measurement prototype for measuring spring tension and other key parameters in brush-holders used in electric motors. It aims to provide the mining industry with a new, fully automatic inspection system that will facilitate maintenance and checking. Our development research was carried out specifically on the brush system of a SAG grinding mill motor. These machines commonly use SIEMENS motors; however, the instrument can be easily adapted to any motor by simply changing the physical dimensions of the prototype.
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Carrasco, M., Alvarez, F., Velazquez, R., Concha, J., & Perez-Cotapos, I. (2018). Inline Force Sensor Development for Electrical Motors for Mining Operations in Chile: A New Inspection Protocol. IEEE Latin Am. Trans., 16(1), 66–74.
Abstract: Electric motors are among the most widely used electro-mechanical systems in the mining industry in Chile. As they are physically present in virtually all phases of the production process, they must be regularly inspected. In order to maintain a maximum level of operability and to avoid the occurrence of catastrophic failures and unscheduled stoppages, regular, planned reviews to measure the internal parameters of their components are performed manually. This part of the process presents serious shortcomings, such as significant inspection times, information input errors and, in some cases, measurement errors resulting from the technical difficulty of physically taking the measurement. This research presents the design, development and evaluation of a new sensor to support the inspection of brush-holder spring tensions as well as the integration of a digital gauge to control other critical dimensions of the brush-holder mounting. Its purpose is to provide the mining industry with a new system and a fully automated inspection protocol to ease maintenance and control tasks, particularly focusing on reducing inspection times. These products are expected to increase the equipment operating life, as well as delivering a maintenance report of the motor's key parameters which directly benefits the Key Performance Indicators (KPI) of mining management
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Carrasco, M., Toledo, P., & Tischler, N. D. (2019). Macromolecule Particle Picking and Segmentation of a KLH Database by Unsupervised Cryo-EM Image Processing. Biomolecules, 9(12), 14 pp.
Abstract: Segmentation is one of the most important stages in the 3D reconstruction of macromolecule structures in cryo-electron microscopy. Due to the variability of macromolecules and the low signal-to-noise ratio of the structures present, there is no generally satisfactory solution to this process. This work proposes a new unsupervised particle picking and segmentation algorithm based on the composition of two well-known image filters: Anisotropic (Perona-Malik) diffusion and non-negative matrix factorization. This study focused on keyhole limpet hemocyanin (KLH) macromolecules which offer both a top view and a side view. Our proposal was able to detect both types of views and separate them automatically. In our experiments, we used 30 images from the KLH dataset of 680 positive classified regions. The true positive rate was 95.1% for top views and 77.8% for side views. The false negative rate was 14.3%. Although the false positive rate was high at 21.8%, it can be lowered with a supervised classification technique.
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Castaneda, P., & Reus, L. (2019). Suboptimal investment behavior and welfare costs: A simulation based approach. Financ. Res. Lett., 30, 170–180.
Abstract: We propose a representation of suboptimal investment behavior based on the stochastic discount factor (SDF) paradigm. Suboptimal investment behavior is rationalized as being the investor's optimal decision under a wrong SDF, while wealth trajectories and budget constraints are based on the true SDF. We develop a novel Monte Carlo simulation approach to compute the welfare costs for this suboptimal behavior. We study the suboptimal portfolio choice under CRRA preferences using two financial market models. The Monte Carlo simulation delivers comparable welfare losses to those computed in the original studies, which are based on partial differential equations (PDE) and – finite-difference schemes.
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Ciarreta, A., Nasirov, S., & Silva, C. (2016). The development of market power in the Spanish power generation sector: Perspectives after market liberalization. Energy Policy, 96, 700–710.
Abstract: This paper provides a comprehensive analysis of the market power problem in the Spanish power generation sector and examines how and to which extent the market has developed in terms of market power concerns after the market liberalization reforms. The methodology applied in this study includes typical ex-post structural and behavioral measures employed to estimate potential for market power, namely: concentration ratios (CR) (for the largest and the three largest suppliers), the Herfindahl-Hirschman Index (HHI), Entropy, Pivotal Supply Index, the Residual Supply Index and Residual Demand Elasticity (RDE). The results are presented for the two largest Spanish generating companies (Endesa and Iberdrola) acting in the Iberian Electricity Market (MIBEL), and in the Spanish Day-ahead electricity market. The results show evidence that these companies have behaved much more competitively in recent periods than in the beginning of the market liberalization. In addition, the paper discusses important structural and regulatory changes through market liberalization processes in the Spanish Day ahead electricity market. (C) 2016 Elsevier Ltd. All rights reserved.
Keywords: Competition; Market power; Spanish electricity market
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Corral, N., Anrique, N., Fernandes, D., Parrado, C., & Caceres, G. (2012). Power, placement and LEC evaluation to install CSP plants in northern Chile. Renew. Sust. Energ. Rev., 16(9), 6678–6685.
Abstract: Chile is expecting a 5.4% growth in energy consumption per year until 2030, requiring new and better solutions for the upward trend of its electricity demand. This state leads to select and study one of the potential alternatives for electricity generation: concentrated solar power (CSP) plants. Such renewable technology found in Chile a very favorable condition. Recent researches indicate Atacama Desert as one of the best regions for solar energy worldwide, having an average radiation higher than in places where CSP plants are currently implemented, e.g. Spain and USA. The aim of this study is to present an analysis of levelized energy cost (LEC) for different power capacities of CSP plants placed in distinct locations in northern Chile. The results showed that CSP plants can be implemented in Atacama Desert with LECs around 19 (sic)US$/kWh when a gas-fired backup and thermal energy storage (TES) systems are fitted. This value increases to approximately 28 (sic)US$/kWh if there is no backup system. (C) 2012 Elsevier Ltd. All rights reserved.
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del Valle, M. A., Ramos, A. C., Diaz, F. R., & Gacitua, M. A. (2015). Electrosynthesis and Characterisation of Polymer Nanowires from Thiophene and its Oligomers. J. Braz. Chem. Soc., 26(11), 2313–2320.
Abstract: Validating methodology formerly reported, polythiophene electrosynthesised as nanowires from the monomer and some of its oligomers is now described. The work is conducted on a platinum electrode previously modified with a template that tunes the polymer growth inside the confined space of the pores. In addition, it was confirmed that the use of larger chain-length oligomers as starting unit helps to obtain more homogeneous wires, although its adhesion to the supporting substrate works against. Characterisation allows to verify the morphology and to confirm higher levels of doping/undoping of the nanostructures as compared to the corresponding bulky deposits, which points to improved macroscopic properties. It is demonstrated that this strategy allows obtaining nanowires of very small diameter, ranging from 2.8 to 4.0 nm; thus demonstrating that the use of this approach enables the direct obtainment of nanowires upon the electrode surface, with the obvious advantage that this implies.
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Donoso, R. A., Ruiz, D., Garate-Castro, C., Villegas, P., Gonzalez-Pastor, J. E., de Lorenzo, V., et al. (2021). Identification of a self-sufficient cytochrome P450 monooxygenase from Cupriavidus pinatubonensis JMP134 involved in 2-hydroxyphenylacetic acid catabolism, via homogentisate pathway. Microb. Biotechnol., 14(5), 1944–1960.
Abstract: The self-sufficient cytochrome P450 RhF and its homologues belonging to the CYP116B subfamily have attracted considerable attention due to the potential for biotechnological applications based in their ability to catalyse an array of challenging oxidative reactions without requiring additional protein partners. In this work, we showed for the first time that a CYP116B self-sufficient cytochrome P450 encoded by the ohpA gene harboured by Cupriavidus pinatubonensis JMP134, a beta-proteobacterium model for biodegradative pathways, catalyses the conversion of 2-hydroxyphenylacetic acid (2-HPA) into homogentisate. Mutational analysis and HPLC metabolite detection in strain JMP134 showed that 2-HPA is degraded through the well-known homogentisate pathway requiring a 2-HPA 5-hydroxylase activity provided by OhpA, which was additionally supported by heterologous expression and enzyme assays. The ohpA gene belongs to an operon including also ohpT, coding for a substrate-binding subunit of a putative transporter, whose expression is driven by an inducible promoter responsive to 2-HPA in presence of a predicted OhpR transcriptional regulator. OhpA homologues can be found in several genera belonging to Actinobacteria and alpha-, beta- and gamma-proteobacteria lineages indicating a widespread distribution of 2-HPA catabolism via homogentisate route. These results provide first time evidence for the natural function of members of the CYP116B self-sufficient oxygenases and represent a significant input to support novel kinetic and structural studies to develop cytochrome P450-based biocatalytic processes.
Keywords: COMPLETE GENOME SEQUENCE; ELECTRON-TRANSFER; GENE; DEGRADATION; SYSTEM; STRAIN; P450BM3; GROWTH; DOMAIN; HYDROXYLATION
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