Display omitted
•PEDOT decreases both charge-transference and LFP lithiation resistances.•PEDOT addition by a blending method yields a specific capacity of 130mAhgLFP−1 at 2C.•New insight into the ...role of conductive materias is obtained by EIS analysis.
Lithium iron phosphate (LFP) cathodes are one of the most promising candidates to find application in hybrid electric vehicle energy storage system. For this reason advances in the performance of its theoretical capacity at high charge/discharge rates is under continuous development. Most used strategies to improve power performance are the addition to the LFP particles of an electric conductive carbon or polymer, such as poly(3,4-ethylenedioxythiophene) PEDOT doped with polystyrene sulfonate (PSS). The data obtained from impedance analysis provide new insight on the role of these additives that not only improve the charge transfer but also favor the lithiation/delithiation processes in the phosphate matrix. Furthermore, PEDOT is capable to reduce the resistances of charge transfer and lithiation reaction inside the phosphate matrix by one order of magnitude in comparison with those achieved with the carbon coating strategy. In this study, the most effective approach has been the addition of PEDOT by a blending method, resulting in a specific capacity of 130mAhgLFP−1 at 2C.
The electrochemical performance as potential negative electrode in lithium-ion batteries of graphite materials that were prepared from two Spanish anthracites of different characteristics by heat ...treatment in the temperature interval 2400–2800
°C are investigated by galvanostatic cycling. The interlayer spacing,
d
002, and crystallite sizes along the
c axis,
L
c
, and the
a axis,
L
a
, calculated from X-ray diffractometry (XRD) as well as the relative intensity of the Raman
D-band,
I
D
/
I
t
, are used to assess the degree of structural order of the graphite materials. The galvanostatic cycling are carried out in the 2.1–0.003
V potential range at a constant current and C/10 rate during 50 cycles versus Li/Li
+. Larger reversible lithium storage capacities are obtained from those anthracite-based graphite materials with higher structural order and crystal orientation. Reasonably good linear correlations were attained between the electrode reversible charge and the materials XRD and Raman crystal parameters. The graphite materials prepared show excellent cyclability as well as low irreversible charge; the reversible capacity being up to ∼250
mA
h
g
−1. From this study, the utilization of anthracite-based graphite materials as negative electrode in lithium-ion batteries appears feasible. Nevertheless, additional work should be done to improve the structural order of the graphite materials prepared and therefore, the reversible capacity.
In this study, a methodology for parametric identification of phenomenological based semiphysical models (PBSMs) is presented. The proposed methodology relies on a hierarchy of the relevance of ...parameters with respect to the model outputs. This hierarchy is accomplished by means of the Hankel matrix of the process model and its singular value decomposition (SVD). In this way, parameters having a major impact on the process output are prioritized. Two concepts, parameter interpretability and sacrifice parameter, are coined to be used in such a methodology. The proposed scheme is tested in simulation by using two realistic examples, both selected as batch processes due to their inherent difficulty:
δ‐endotoxins production by means of Bacillus thuringiensis and the production of polyhydroxyalkanoates (PHA). Our results show a reduction of 92 % and 39 % in the integral of time‐weighted absolute error (ITAE), in the first and second examples, respectively, with respect to a conventional identification procedure.
The bacterial chromosome is compacted in a manner optimal for DNA transactions to occur. The degree of compaction results from the level of DNA-supercoiling and the presence of nucleoid-binding ...proteins. DNA-supercoiling is homeostatically maintained by the opposing activities of relaxing DNA topoisomerases and negative supercoil-inducing DNA gyrase. DNA-supercoiling acts as a general
regulator of transcription, which can be superimposed upon other types of more specific
regulatory mechanism. Transcriptomic studies on the human pathogen
, which has a relatively small genome (∼2 Mb) and few nucleoid-binding proteins, have been performed under conditions of local and global changes in supercoiling. The response to local changes induced by fluoroquinolone antibiotics, which target DNA gyrase subunit A and/or topoisomerase IV, involves an increase in oxygen radicals which reduces cell viability, while the induction of global supercoiling changes by novobiocin (a DNA gyrase subunit B inhibitor), or by seconeolitsine (a topoisomerase I inhibitor), has revealed the existence of topological domains that specifically respond to such changes. The control of DNA-supercoiling in
occurs mainly via the regulation of topoisomerase gene transcription: relaxation triggers the up-regulation of gyrase and the down-regulation of topoisomerases I and IV, while hypernegative supercoiling down-regulates the expression of topoisomerase I. Relaxation affects 13% of the genome, with the majority of the genes affected located in 15 domains. Hypernegative supercoiling affects 10% of the genome, with one quarter of the genes affected located in 12 domains. However, all the above domains overlap, suggesting that the chromosome is organized into topological domains with fixed locations. Based on its response to relaxation, the pneumococcal chromosome can be said to be organized into five types of domain: up-regulated, down-regulated, position-conserved non-regulated, position-variable non-regulated, and AT-rich. The AT content is higher in the up-regulated than in the down-regulated domains. Genes within the different domains share structural and functional characteristics. It would seem that a topology-driven selection pressure has defined the chromosomal location of the metabolism, virulence and competence genes, which suggests the existence of topological rules that aim to improve bacterial fitness.
Summary
This paper addresses the problem of estimating the state for a class of uncertain discrete‐time linear systems with constraints by using an optimization‐based approach. The proposed scheme ...uses the moving horizon estimation philosophy together with the game theoretical approach to the
H∞ filtering to obtain a robust filter with constraint handling. The used approach is constructive since the proposed moving horizon estimator (MHE) results from an approximation of a type of full information estimator for uncertain discrete‐time linear systems, named in short
H∞‐MHE and
H∞–full information estimator, respectively. Sufficient conditions for the stability of the
H∞‐MHE are discussed for a class of uncertain discrete‐time linear systems with constraints. Finally, since the
H∞‐MHE needs the solution of a complex minimax optimization problem at each sampling time, we propose an approximation to relax the optimization problem and hence to obtain a feasible numerical solution of the proposed filter. Simulation results show the effectiveness of the robust filter proposed.
The spread of multidrug-resistant isolates of
requires the discovery of new drugs directed to new targets. In this study, we investigated the activity of two boldine-derived alkaloids, seconeolitsine ...(SCN) and
-methyl-seconeolitsine (
-SCN), against
. These compounds have been shown to target DNA topoisomerase I enzyme and inhibit growth of
. Both SCN and
-SCN inhibited
growth at 1.95-15.6 μM, depending on the strain. In
this inhibitory effect correlated with the amount of topoisomerase I in the cell, hence demonstrating that this enzyme is the target for these alkaloids in mycobacteria. The gene coding for topoisomerase I of strain H37Rv (MtbTopoI) was cloned into pQE1 plasmid of
. MtbTopoI was overexpressed with an N-terminal 6-His-tag and purified by affinity chromatography.
inhibition of MtbTopoI activity by SCN and
-SCN was tested using a plasmid relaxation assay. Both SCN and
-SCN inhibited 50% of the enzymatic activity at 5.6 and 8.4 μM, respectively. Cleavage of single-stranded DNA was also inhibited with SCN. The effects on DNA supercoiling were also evaluated
in plasmid-containing cultures of
. Plasmid supercoiling densities were -0.060 in cells untreated or treated with boldine, and -0.072 in 1 × MIC
-SCN treated cells, respectively, indicating that the plasmid became hypernegatively supercoiled in the presence of
-SCN. Altogether, these results demonstrate that the
topoisomerase I enzyme is an attractive drug target, and that SCN and
-SCN are promising lead compounds for drug development.
Proteins belonging to the Gls24 superfamily are involved in survival of pathogenic Gram-positive cocci under oligotrophic conditions and other types of stress, by a still unknown molecular mechanism. ...In Firmicutes, this superfamily includes three different valine-rich orthologal families (Gls24A, B, C) with different potential interactive partners. Whereas the Streptococcus pneumoniae Δgls24A deletion mutant experienced a general long growth delay, the Δgls24B mutant grew as the parental strain in the semisynthetic AGCH medium but failed to grow in the complex Todd-Hewitt medium. Bovine seroalbumin (BSA) was the component responsible for this phenotype. The effect of BSA on growth was concentration-dependent and was maintained when the protein was proteolyzed but not when heat-denatured, suggesting that BSA dependence was related to oligopeptide supplementation. Global transcriptional analyses of the knockout mutant revealed catabolic derepression and induction of chaperone and oligopeptide transport genes. This mutant also showed increased sensibility to cadmium and high temperature. The Δgls24B mutant behaved as a poor colonizer in the nasopharynx of mice and showed 20-fold competence impairment. Experimental data suggest that Gls24B plays a central role as a sensor of amino acid availability and its connection to sugar catabolism. This metabolic rewiring can be compensated in vitro, at the expenses of external oligopeptide supplementation, but reduce important bacteria skills prior to efficiently address systemic virulence traits. This is an example of how metabolic factors conserved in enterococci, streptococci, and staphylococci can be essential for survival in poor oligopeptide environments prior to infection progression.
Empirical and phenomenological-based models are used to represent biological and physiological processes. Phenomenological models are derived from the knowledge of the mechanisms that underlie the ...behavior of the system under study, while empirical models are derived from data analysis to quantify relationships between variables of interest. For studying biological systems, the phenomenological modeling approach offers the great advantage of having a structure with variables and parameters with physical meaning that enhance the interpretability of the model and its further use for decision making. The interpretability property of models, however, remains a vague concept. In this study, we addressed the interpretability property for parameters of phenomenological-based models. To our knowledge, this property has not been deeply discussed, perhaps by the implicit assumption that interpretability is inherent to phenomenological-based models. We propose a conceptual framework to address parameter interpretability and its implications for parameter identifiability, using a simple but relevant model representing the enzymatic degradation of β−casein by a Lactococcus lactis bacterium. We illustrated the usefulness of integrating parameter interpretability in the process of construction and exploitation of phenomenological models.
•Definition of parameters interpretability in phenomenological-based semiphysical models.•Construction of conceptual framework on parameters interpretability to use in bioscience and medicine fields.•Relationship between identifiability and interpretability concepts.•Incorporation of parameter interpretability for model construction by using a simple mode.
Introduction
Systemic lupus erythematosus (SLE) is the prototypic autoimmune disease that disrupts numerous immunity mechanisms with the potential to exert damage to any organ or tissue. Its etiology ...remains uncertain; however, genetic and environmental factors that differ between populations strongly influence its development. Among the physiopathogenic factors, the genetic ones predominate, notably the major histocompatibility complex (MHC) loci. A high degree of ethnical admixture makes Mexican Mestizos a thoroughly genetically heterogeneous population. Therefore, this study aimed to identify the MHC polymorphisms associated with SLE development in Mexican Mestizos from Southern Mexico and compare them with patients from Mexico City.
Method
A transversal study in SLE patients from Tapachula, Chiapas, was conducted. DNA typing of human leukocyte antigens (HLA) classes I and II was performed using single specific primers (SSP). Admixture analysis was performed using the population genetics LEADMIX software.
Results
The frequencies of HLA-DRB1*16 and HLA-DQB1*05 were found to have a tendency towards increase in SLE patients, compared to ethnically matched healthy controls. The allele HLA-DRB1*03 seemed to be less associated with SLE in this group of Mexican Mestizos, opposed to other more Caucasian populations. Admixture analysis showed a higher Mayan genetic component in these patients from Chiapas.
Conclusions
The genetic susceptibility for SLE differed in two populations of Mexican Mestizos with dissimilar ethnic ancestries. Autochthonous Amerindian alleles, and not the more widely known Caucasian alleles, might be associated with the susceptibility to SLE in Mexican Mestizos from Tapachula, Chiapas.
Key Points
•
Autochthonous Amerindian alleles, such as HLA-DRB1*16, had a tendency to be increased in SLE patients, compared to healthy controls.
•
SLE susceptibility alleles vary considerably among regions in Mexico, according to the distribution of the indigenous groups.
•
Ethnic admixture is a key determinant in the genetic susceptibility of SLE.
PDF
