Tuning Electronic and Structural Properties of Lead-Free Metal Halide Perovskites: A Comparative Study of 2D Ruddlesden-Popper and 3D Compositions.

In recent decades, two-dimensional (2D) perovskites have emerged as promising semiconductors for next-generation photovoltaics, showing notable advancements in solar energy conversion. Herein, we explore the impact of alternative inorganic lattice BX-based compositions (B=Ge or Sn, X=Br or I) on the energy gap and stability. Our investigation encompasses BA2Man-1BnX3n+1 2D Ruddlesden-Popper perovskites (for n=1-5 layers) and 3D bulk (MA)BX3 systems, employing first-principles calculations with spin-orbit coupling (SOC), DFT-1/2 quasiparticle, and D3 dispersion corrections. The study unveils how atoms with smaller ionic radii induce anisotropic internal and external distortions within the inorganic and organic lattices. Introducing the spacers in the low-layer regime reduces local distortions but widens band gaps. Our calculation protocol provides deeper insights into the physics and chemistry underlying 2D perovskite materials, paving the way for optimizing environmentally friendly alternatives that can efficiently replace with sustainable materials.

Unveiling excitons in two-dimensional ß -pnictogens.

In this paper, we investigate the optical, electronic, vibrational, and excitonic properties of four two-dimensional ß -pnictogen materials-nitrogenene, phosphorene, arsenene, and antimonene-via density functional theory calculations and the Bethe-Salpeter equation. These materials possess indirect gaps with significant exciton binding energies, demonstrating isotropic behavior under circular light polarization and anisotropic behavior under linear polarization by absorbing light within the visible solar spectrum (except for nitrogenene). Furthermore, we observed that Raman frequencies red-shift in heavier pnictogen atoms aligning with experimental observations; simultaneously, quasi-particle effects notably influence the linear optical response intensively. These monolayers' excitonic effects lead to optical band gaps optimized for solar energy harvesting, positioning them as promising candidates for advanced optoelectronic device applications.

Cage doping of Ti, Zr, and Hf-based 13-atom nanoclusters: two sides of the same coin.

Transition metal nanoclusters can exhibit unique and tunable properties which result not only from their chemical composition but also from their atomic packing and quantized electronic structures. Here, we introduce a promising family of bimetallic TM@Ti12, TM@Zr12, and TM@Hf12 nanoclusters with icosahedral geometry, where TM represents an atom from groups 3 to 12. Density functional theory calculations show that their stability can be explained with familiar concepts of metal cluster electronic and atomic shell structures. The magnetic properties of these quasispherical clusters are entirely consistent with superatom electronic shells and Hund's rules, and can be tuned by the choice of the TM dopant. The computed cluster atomization energies were analyzed in terms of the elements' cohesive energy, Ecoh, and contributions from geometric distortion, Edis, surface energy, Es, and ionic bonding, Ei. Some clusters have anomalous stability relative to Ecoh + Edis + Es + Ei. We attribute this to superatomic character associated with a favorable atomic and electronic shell structure. This raises the possibility of designing stable superatoms and materials with tailored electronic and magnetic properties.

Improved detection and phylogenetic analysis of plant proteins containing LysM domains.

Plants perceive N-acetyl-d-glucosamine-containing oligosaccharides that play a role in the interaction with bacteria and fungi, through cell-surface receptors containing a tight bundle of three LysM domains in their extracellular region. However, the identification of LysM domains of receptor-like kinases (RLK)/receptor-like proteins (RLP) using sequence based methods has led to some ambiguity, as some proteins have been annotated with only one or two LysM domains. This missing annotation was likely produced by the failure of the LysM hidden Markov model (HMM) from the Pfam database to correctly identify some LysM domains in proteins of plant origin. In this work, we provide improved HMMs for LysM domain detection in plants, that were built from the structural alignment of manually curated LysM domain structures from the Protein Data Bank and AlphaFold Protein Structure Database. Furthermore, we evaluated different sets of ligand-specific HMMs that were able to correctly classify a limited set of fully characterised RLK/Ps by their ligand specificity. In contrast, the phylogenetic analysis of the extracellular region of RLK/Ps, or of their individual LysM domains, was unable to discriminate these proteins by their ligand specificity. The HMMs reported here will allow a more sensitive detection of plant proteins containing LysM domains and help improve their characterisation.

Promising TMDC-like optical and excitonic properties of the TiBr2 2H monolayer.

The presented simulation protocol provides a solid foundation for exploring two-dimensional materials. Taking the TiBr2 2H monolayer as an example, this material displays promising TMDC-like optical and excitonic properties, making it an excellent candidate for optoelectronic and valleytronic applications. The direct band gap semiconductor (1.19 eV) is both structurally and thermodynamically stable, with spin-orbit coupling effects revealing a broken mirror symmetry in the K and K' valleys of the band structure, as confirmed by opposite values of the Berry curvature. A direct and bright exciton ground state was found, with an exciton binding energy of 0.56 eV. The study also revealed an optical helicity selection rule, suggesting selectivity in the valley excitation by specific circular light polarizations.

Unveiling oxygen vacancy impact on lizardite thermo and mechanical properties.

Here, we performed a systematic DFT study assisted by the workflow framework SimStack for the mechanical and thermodynamic properties of the clay mineral lizardite in pristine and six different types of O vacancies configurations. In most cases, the defect caused a structural phase transition in the lizardite from the trigonal (pristine) to the triclinic phase. The results show that oxygen vacancies in lizardite significantly reduce the lattice thermal conductivity, accompanied by an elastic moduli reduction and an anisotropy index increase. Through the P-V relation, an increase in compressibility was evidenced for vacancy configurations. Except for the vacancy with the same crystalline structure as pristine lizardite, the sound velocities of the other vacancy configurations produce a decrease in these velocities, and it is essential to highlight high values for the Grüneisen parameter. We emphasize the great relevance of the punctual-defects introduction, such as O vacancies, in lizardite, since this microstructural design is responsible for the decrease of the lattice thermal conductivity in comparison with the pristine system by decreasing the heat transfer ability, turning lizardite into a promising candidate for thermoelectric materials.

Optimizing congenital cytomegalovirus detection by pool testing in saliva by a rapid molecular test.

Universal congenital cytomegalovirus (cCMV) screening in saliva is increasingly recommended. The aim of our study was to correlate the performance of a point-of-care rapid molecular test with CMV real time PCR (CMV RT-PCR) detection, using saliva pool-testing in newborns under a universal screening strategy. Saliva swabs were prospectively collected from newborns < 21 days old and tested by Alethia-LAMP-CMV assay in pools of 5 samples. In positive pools, subjects were tested individually and by saliva and urine CMV RT-PCR. A subset of negative pools were studied with both techniques and viral loads in whole blood were determined in positive patients. From 1,642 newborns included in 328 pools, 8 were confirmed by urine CMV RT-PCR, (cCMV prevalence 0,49%). The PPA and NNA of the pooled saliva Alethia-LAMP-CMV testing were 87,5% and 99,8% with a negative and positive predictive value of 99,9% and 77,7%, respectively. Two false positives were detected (0,12%). A subset of 17 negative pools (85 samples), studied by saliva CMV RT-PCR, showed 100% concordance.  Conclusion: CMV pool-testing using a rapid molecular test in saliva proved feasible when compared to PCR gold standards. This strategy could improve cost-effectiveness for cCMV universal neonatal screening, based on the low prevalence of the infection and could be a more affordable approach in less developed regions with reduced detection capacity. What is Known: • cCMV is the most frequent congenital infection and a leading nongenetic cause of sensorineural hearing loss and brain disease. • Universal screening could allow early detection of congenitally infected infants, improving clinical outcome. • Saliva PCR is the preferred and non-invasive test for newborn cCMV screening. What is New: • The feasibility of a universal cCMV screening by pool-testing in saliva using a rapid test in pools of 5 samples. • PPA and NPA were 87,5 and 99,8% compared to CMV PCR in urine. • This strategy could be relevant specially in LMIC where detection capacity is reduced and could improve cost-effectiveness. • cCMV prevalence in our center was 0,49%.

Effect of a nitrogenous nanocomposite on leaching and N content in lettuce in soil columns.

Nanofertilizers could promote nutrient efficiency with slow release compared to conventional fertilizers (CF). Most of the applied nitrogen is lost on the soil by leaching, due to the rapid release behavior of CF. Clays can function as a nanosized porous structure to retain and slowly release nutrients. The objective of this study was to evaluate a nitrogenous nanocomposite (NCN) and its effect on leaching and N content of lettuce (Lactuca sativa). The treatments applied were: 100% conventional fertilizer, 100% nitrogenous nanocomposite and the mixture in percentage of CF/NCN 25/75, 50/50, 75/25 and 25/0, 50/0 75/0% on columns of soil with lettuce for 45 days. Leachates at the end of the cycle increased in treatments with NCN. Treatments with NCN have higher N content in the leaf. In regard to biomass growth, leaf area, leaf N, drained variables, electrical conductivity and NO3- content, it was possible to show that the doses of 50 and 75% of NCN match the characteristics of the crop compared to the control, which allows us to use lower doses than those recommended with CFs.

MXene-Based Nanocomposites for Piezoelectric and Triboelectric Energy Harvesting Applications.

Due to its superior advantages in terms of electronegativity, metallic conductivity, mechanical flexibility, customizable surface chemistry, etc., 2D MXenes for nanogenerators have demonstrated significant progress. In order to push scientific design strategies for the practical application of nanogenerators from the viewpoints of the basic aspect and recent advancements, this systematic review covers the most recent developments of MXenes for nanogenerators in its first section. In the second section, the importance of renewable energy and an introduction to nanogenerators, major classifications, and their working principles are discussed. At the end of this section, various materials used for energy harvesting and frequent combos of MXene with other active materials are described in detail together with the essential framework of nanogenerators. In the third, fourth, and fifth sections, the materials used for nanogenerators, MXene synthesis along with its properties, and MXene nanocomposites with polymeric materials are discussed in detail with the recent progress and challenges for their use in nanogenerator applications. In the sixth section, a thorough discussion of the design strategies and internal improvement mechanisms of MXenes and the composite materials for nanogenerators with 3D printing technologies are presented. Finally, we summarize the key points discussed throughout this review and discuss some thoughts on potential approaches for nanocomposite materials based on MXenes that could be used in nanogenerators for better performance.

Response of two cyanobacterial strains to non-biodegradable glitter particles.

Microplastic pollution is a growing concern mainly in aquatic environments due to its deleterious effects. Some types of microplastics, such as glitter, remain overlooked. Glitter particles are artificial reflective microplastics used by different consumers within arts and handcraft products. In nature, glitter can physically affect phytoplankton by causing shade or acting as a sunlight-reflective surface, influencing primary production. This study aimed to evaluate the effects of five concentrations of non-biodegradable glitter particles in two bloom-forming cyanobacterial strains, Microcystis aeruginosa CENA508 (unicellular) and Nodularia spumigena CENA596 (filamentous). Cellular growth rate, estimated by optical density (OD), demonstrated that the applied highest glitter dosage decreases cyanobacterial growth rate with a more evident effect on M. aeruginosa CENA508. The cellular biovolume of N. spumigena CENA596 increased following the application of high concentrations of glitter. Still, no significant difference was detected in chlorophyll-a and carotenoids' contents for both strains. These results suggest that environmental concentrations of glitter, similar to the highest dosage tested (>200 mg glitter L-1), may negatively influence susceptible organisms of the aquatic ecosystems, as observed with M. aeruginosa CENA508 and N. spumigena CENA596.

Revealing the impact of organic spacers and cavity cations on quasi-2D perovskites via computational simulations.

Two-dimensional hybrid lead iodide perovskites based on methylammonium (MA) cation and butylammonium (BA) organic spacer-such as [Formula: see text]-are one of the most explored 2D hybrid perovskites in recent years. Correlating the atomistic profile of these systems with their optoelectronic properties is a challenge for theoretical approaches. Here, we employed first-principles calculations via density functional theory to show how the cation partially canceled dipole moments through the [Formula: see text] terminal impact the structural/electronic properties of the [Formula: see text] sublattices. Even though it is known that at high temperatures, the organic cation assumes a spherical-like configuration due to the rotation of the cations inside the cage, our results discuss the correct relative orientation according to the dipole moments for ab initio simulations at 0 K, correlating well structural and electronic properties with experiments. Based on the combination of relativistic quasiparticle correction and spin-orbit coupling, we found that the MA horizontal-like configuration concerning the inorganic sublattice surface leads to the best relationship between calculated and experimental gap energy throughout n = 1, 2, 3, 4, and 5 number of layers. Conversely, the dipole moments cancellation (as in BA-MA aligned-like configuration) promotes the closing of the gap energies through an electron depletion mechanism. We found that the anisotropy [Formula: see text] isotropy optical absorption conversion (as a bulk convergence) is achieved only for the MA horizontal-like configuration, which suggests that this configuration contribution is the majority in a scenario under temperature effects.

How cation nature controls the bandgap and bulk Rashba splitting of halide perovskites.

Because of instability issues presented by metal halide perovskites based on methylammonium (MA), its replacement to Cs has emerged as an alternative to improve the materials' durability. However, the impact of this replacement on electronic properties, especially gap energy and bulk Rashba splitting remains unclear since electrostatic interactions from organic cations can play a crucial role. Through first-principles calculations, we investigated how organic/inorganic cations impact the electronic properties of MAPbI 3 and CsPbI 3 perovskites. Although at high temperatures the organic cation can assume spherical-like configurations due to its rotation into the cages, our results provide a complete electronic mechanism to show, from a chemical perspective based on ab initio calculations at 0 K , how the MA dipoles suppression can reduce the MAPbI 3 gap energy by promoting a degeneracy breaking in the electronic states from the PbI 3 framework, while the dipole moment reinforcement is crucial to align theory ↔ experiment, increasing the bulk Rashba splitting through higher Pb off-centering motifs. The lack of permanent dipole moment in Cs results in CsPbI 3 polymorphs with a pronounced Pb on-centering-like feature, which causes suppression in their respective bulk Rashba effect.

Heat tolerance of marine ectotherms in a warming Antarctica.

Global warming is affecting the Antarctic continent in complex ways. Because Antarctic organisms are specialized to living in the cold, they are vulnerable to increasing temperatures, although quantitative analyses of this issue are currently lacking. Here we compiled a total of 184 estimates of heat tolerance belonging to 39 marine species and quantified how survival is affected concomitantly by the intensity and duration of thermal stress. Species exhibit thermal limits displaced toward colder temperatures, with contrasting strategies between arthropods and fish that exhibit low tolerance to acute heat challenges, and brachiopods, echinoderms, and molluscs that tend to be more sensitive to chronic exposure. These differences might be associated with mobility. A dynamic mortality model suggests that Antarctic organisms already encounter temperatures that might be physiologically stressful and indicate that these ecological communities are indeed vulnerable to ongoing rising temperatures.

El calentamiento global está afectando al continente antártico de formas complejas. Dado que los organismos antárticos están especializados a vivir en el frío, son vulnerables al aumento de las temperaturas, aunque en la actualidad hay carencia de análisis cuantitativos al respecto. Aquí recopilamos un total de 184 estimaciones de tolerancia al calor pertenecientes a 39 especies marinas, y cuantificamos cómo la supervivencia de estos organismos se ve afectada concomitantemente por la intensidad y la duración de un estrés térmico. Efectivamente las especies antárticas muestran límites térmicos desplazados hacia temperaturas más frías, con estrategias contrastadas entre los artrópodos y los peces que muestran una baja tolerancia a los desafíos térmicos agudos, y los braquiópodos, equinodermos y moluscos que tienden a ser más sensibles a la exposición crónica. Estas diferencias podrían estar asociadas con la movilidad. Un modelo dinámico de mortalidad sugiere que los organismos antárticos ya se enfrentan a temperaturas que podrían ser fisiológicamente estresantes e indican que estas comunidades ecológicas son realmente vulnerables al aumento continuo de las temperaturas.

Molecular adsorption on coinage metal subnanoclusters: A DFT+D3 investigation.

Gold and silver subnanoclusters with few atoms are prominent candidates for catalysis-related applications, primarily because of the large fraction of lower-coordinated atoms exposed and ready to interact with external chemical species. However, an in-depth energetic analysis is necessary to characterize the relevant terms within the molecular adsorption process that can frame the interactions within the Sabatier principle. Herein, we investigate the interaction between Agn and Aun subnanoclusters (clu, n = 2-7) and N2 , NO, CO, and O2 molecules, using scalar-relativistic density functional theory calculations within van der Waals D3 corrections. The onefold top site is preferred for all chemisorption cases, with a predominance of linear (≈180°) and bent (≈120°) molecular geometries. A larger magnitude of adsorption energy is correlated with smaller distances between molecules and clusters and with the weakening of the adsorbates bond strength represented by the increase of the equilibrium distances and decrease of molecular stretching frequencies. From the energetic decomposition, the interaction energy term was established as an excellent descriptor to classify subnanoclusters in the adsorption/desorption process concomitant with the Sabatier principle. The limiting cases: (i) weak molecular adsorption on the subnanoclusters, which may compromise the reaction activation, where an interaction energy magnitude close to 0 eV is observed (e.g., physisorption in N2 /Ag6 ); and (ii) strong molecular interactions with the subnanoclusters, given the interaction energy magnitude is larger than at least one of the individual fragment binding energies (e.g., strong chemisorption in CO/Au4 and NO/Au4 ), conferring a decrease in the desorption rate and an increase in the possible poisoning rate. However, the intermediate cases are promising by involving interaction energy magnitudes between zero and fragment binding energies. Following the molecular closed-shell (open-shell) electronic configuration, we find a predominant electrostatic (covalent) nature of the physical interactions for N2 ⋯clu and CO ⋯clu (O2 ⋯clu and NO⋯clu), except in the physisorption case (N2 /Ag6 ) where dispersive interaction is dominant. Our results clarify questions about the molecular adsorption on subnanoclusters as a relevant mechanistic step present in nanocatalytic reactions.

Checklist of the fish fauna of the Munim River Basin, Maranhão, north-eastern Brazil.

Background: The Maranhão State harbours great fish diversity, but some areas are still undersampled or little known, such as the Munim River Basin in the northeast of the State. This lack of knowledge is critical when considering anthropogenic impacts on riverine systems especially in the face of major habitat destruction. These pressing threats mean that a comprehensive understanding of diversity is critical and fish checklists extremely relevant. Therefore, the present study provides a checklist of the fish species found in the Munim River Basin, Maranhão State, north-eastern Brazil, based on collected specimens. New information: A total of 123 species were recorded for the Munim River Basin, with only two non-native species, Oreochromisniloticus and Colossomamacropomum, showing that the fish assemblage has relatively high ecological integrity. In addition, 29 species could not be identified at the species level, indicating the presence of species that are probably new to science in the Basin. A predominance of species belonging to the fish orders Characiformes and Siluriformes, with Characidae being recovered as the most species-rich family (21 species) agrees with the general pattern for river basins in the Neotropical Region. The total fish diversity was estimated by extensive fieldwork, including several sampling gears, carried out in different seasons (dry and rainy) and exploring different environments with both daily and nocturnal sampling, from the Basin's source to its mouth. A total of 84 sites were sampled between 2010 and 2022, resulting in 12 years of fieldwork. Fish assemblages were distinct in the Estuary and Upper river basin sections and more similar in the Lower and Middle sections indicating environmental filtering processes. Species were weakly nested across basin sections, but unique species were found in each section (per Simpsons Index). High variability of species richness in the Middle river basin section is likely due to microhabitat heterogeneity supporting specialist fish communities.

MXene/Ferrite Magnetic Nanocomposites for Electrochemical Supercapacitor Applications.

MXene has been identified as a new emerging material for various applications including energy storage, electronics, and bio-related due to its wider physicochemical characteristics. Further the formation of hybrid composites of MXene with other materials makes them interesting to utilize in multifunctional applications. The selection of magnetic nanomaterials for the formation of nanocomposite with MXene would be interesting for the utilization of magnetic characteristics along with MXene. However, the selection of the magnetic nanomaterials is important, as the magnetic characteristics of the ferrites vary with the stoichiometric composition of metal ions, particle shape and size. The selection of the electrolyte is also important for electrochemical energy storage applications, as the electrolyte could influence the electrochemical performance. Further, the external magnetic field also could influence the electrochemical performance. This review briefly discusses the synthesis method of MXene, and ferrite magnetic nanoparticles and their composite formation. We also discussed the recent progress made on the MXene/ferrite nanocomposite for potential applications in electrochemical supercapacitor applications. The possibility of magnetic field-assisted supercapacitor applications with electrolyte and electrode materials are discussed.

Association of bovine viral diarrhea virus, bovine herpesvirus 1, and Neospora caninum with late embryonic losses in highly supplemented grazing dairy cows.

The objectives of this study were: 1- to evaluate the association of Bovine Viral Diarrhea Virus (BVDV), Bovine Herpes Virus 1 (BoHV-1), and Neospora caninum (N. caninum) with the risk for Late Embryonic Loss (LEL) in grazing dairy cows, 2- to evaluate blood progesterone concentration at the time of LEL occurrence, and 3- to describe a novel ultrasound-guided technique for conceptus sampling. We run a prospective cohort study involving 92 cows (46 LEL and 46 NLEL). An LEL cow was that having an embryo with no heartbeat, detached membranes, or floating structures, including embryo remnants detected at pregnancy check by ultrasonography (US) 28-42 days post-AI, whereas an NLEL cow was that with embryo heartbeats detectable by US at pregnancy check 28-42 d post-IA. We took two blood samples from every cow at pregnancy check by US (the day of LEL detection) and 28 d later to perform serological diagnosis of BVDV, BoHV-1, and N. caninum; and to measure blood progesterone concentration at pregnancy check (28-42 d post-AI). We also sampled the conceptus from all the LEL cows. We performed PCR to detect BVDV, BoHV-1, and N. caninum in sampled conceptuses from LEL cows. Finally, we evaluated the associations of risk factors (serological titers, seroconversion, and progesterone) with LEL odds with logistic models. The risk for LEL was associated with serological titers to BVDV (P = 0.03) and tended to be associated with seroconversion to BVDV, given that 19.6% (9/46) in LEL and 6.5% (3/46) in NLEL cows seroconverted to BVDV (P = 0.09). In addition, BVDV was detected in conceptuses from LEL cows that seroconverted to BVDV but not in LEL cows that did not seroconvert. Conversely, the risk for LEL was not associated with the titers or seroconversion to BoHV-1 and N. caninum. BoHV-1 and N. caninum were not identified in any of the conceptuses. Finally, blood progesterone concentration was similar in LEL and NLEL cows, and it was not associated with the risk for LEL (P = 0.54). In conclusion, BVDV infection is a risk factor for LEL in dairy cows.

Characterization of Adherent-Invasive Escherichia coli (AIEC) Outer Membrane Proteins Provides Potential Molecular Markers to Screen Putative AIEC Strains.

Adherent-invasive E. coli (AIEC) is a pathotype associated with the etiopathogenesis of Crohn's disease (CD), albeit with an as-yet unclear role. The main pathogenic mechanisms described for AIEC are adherence to epithelial cells, invasion of epithelial cells, and survival and replication within macrophages. A few virulence factors have been described as participating directly in these phenotypes, most of which have been evaluated only in AIEC reference strains. To date, no molecular markers have been identified that can differentiate AIEC from other E. coli pathotypes, so these strains are currently identified based on the phenotypic characterization of their pathogenic mechanisms. The identification of putative AIEC molecular markers could be beneficial not only from the diagnostic point of view but could also help in better understanding the determinants of AIEC pathogenicity. The objective of this study was to identify molecular markers that contribute to the screening of AIEC strains. For this, we characterized outer membrane protein (OMP) profiles in a group of AIEC strains and compared them with the commensal E. coli HS strain. Notably, we found a set of OMPs that were present in the AIEC strains but absent in the HS strain. Moreover, we developed a PCR assay and performed phylogenomic analyses to determine the frequency and distribution of the genes coding for these OMPs in a larger collection of AIEC and other E. coli strains. As result, it was found that three genes (chuA, eefC, and fitA) are widely distributed and significantly correlated with AIEC strains, whereas they are infrequent in commensal and diarrheagenic E. coli strains (DEC). Additional studies are needed to validate these markers in diverse strain collections from different geographical regions, as well as investigate their possible role in AIEC pathogenicity.

Bacteria from gut microbiota associated with diarrheal infections in children promote virulence of Shiga toxin-producing and enteroaggregative Escherichia coli pathotypes.

Background: Diarrheagenic E. coli (DEC) pathogenicity relies on the interaction of bacteria with the host's gut environment, which is regulated by the resident microbiota. Previously, we identified indicative bacterial species of gut microbiota in DEC-positive stool samples from children. Here, we evaluated the role of two indicative species, Citrobacter werkmanii (CW) and Escherichia albertii (EA), in the virulence of two DEC pathotypes, Shiga toxin-producing (STEC) and enteroaggregative (EAEC) Escherichia coli. Methods: We determined the effect of supernatants obtained from CW and EA cultures on the gene expression of STEC strain 86-24 and EAEC strain 042 by RNA-seq analysis. We evaluated IL-8 secretion from T84 cells infected with these DEC strains in the presence or absence of the supernatant from EA. The effect of the supernatant from EA on the growth and adherence of STEC and EAEC to cells was also evaluated. Finally, we studied the effect of the EA supernatant on the STEC-induced inflammation mediated by the long polar fimbriae (Lpf) in T84 cells and the expression of plasmid-encoded toxin (Pet) in EAEC. Results: RNA-seq analysis revealed that several virulence factors in STEC and EAEC were upregulated in the presence of supernatants from CW and EA. Interestingly, an increase in the secretion of IL-8 was observed in cells infected with STEC or EAEC in the presence of a supernatant from EA. Similar results were observed with the supernatants obtained from clinical strains of E. albertii. The supernatant from EA had no effect on the growth of STEC and EAEC, or on the ability of these DEC strains to adhere to cells. We found that Pet toxin in EAEC was upregulated in the presence of a supernatant from EA. In STEC, using mutant strains for Lpf fimbriae, our data suggested that these fimbriae might be participating in the increase in IL-8 induced by STEC in cells in the presence of a supernatant from EA. Conclusion: Supernatant obtained from an indicative species of DEC-positive diarrhea could modulate gene expression in STEC and EAEC, and IL-8 secretion induced by these bacteria. These data provide new insights into the effect of gut microbiota species in the pathogenicity of STEC and EAEC.

Finger front propagation in smectic-A Fréedericksz transition.

Systems with multistability are characterized by exhibiting complex nonlinear waves between equilibria. Experimentally, near the smectic-A to chiral nematic transition in a liquid crystal mixture cell with planar anchoring, we observe finger fronts emerge in the smectic-A phase when applying an electric field, a reorientation transition. Finger fronts propagate in the direction orthogonal to the anchoring. Colorimetry characterization allows us to describe the molecular reorientation transition and front dynamics. We reveal that the reorientation transition is of the first-order type and determine their critical points. The front speed is determined as a function of the applied voltage. Theoretically, based on a prototype model of liquid crystal transitions, we qualitatively describe the experimental observations. We have analytically determined the bifurcation diagram and the propagation speeds of finger fronts, finding a fair agreement with the experimental observations.