Electro-, photo-, and photoelectrochemical degradation of chloramphenicol on self-doping Ti nanotubes.

In this work, the photo-, electro-, and photo-electro-oxidation of chloramphenicol was investigated. The photo-experiments were carried out with different irradiation sources (an ultraviolet and a simulated solar source) using self-doped titanium nanotubes (SDTNT), a very promising and innovative material that deserves further investigations in the degradation of different pollutants. The photo-electrooxidation (j = 15 mA cm-2) under simulated solar irradiation presented the best efficiency, with ca. 100% degradation and kinetic constant of k = 0.04427 min-1. The FTIR analysis demonstrated a structural modification of the standard molecule occurred for all conditions used, suggesting a modification in functional groups responsible for the biological activity. Furthermore, the TOC analysis showed a significant mineralization of the pollutant (66% from the initial concentration). In addition, both photo-electrooxidation approaches have demonstrated a positive value of S, where the simulated solar irradiation reached the highest value S = 0.6960. The experimental results pointed out evidence that the methodology employed herein for chloramphenicol degradation is greatly interesting and the photo-electrooxidation under simulated solar irradiation is a promising approach for this purpose.

Bismuthene - Tetrahedral DNA nanobioconjugate for virus detection.

In this work, we present an electrochemical sensor for fast, low-cost, and easy detection of the SARS-CoV-2 spike protein in infected patients. The sensor is based on a selected combination of nanomaterials with a specific purpose. A bioconjugate formed by Few-layer bismuthene nanosheets (FLB) and tetrahedral DNA nanostructures (TDNs) is immobilized on Carbon Screen-Printed Electrodes (CSPE). The TDNs contain on the top vertex an aptamer that specifically binds to the SARS-CoV-2 spike protein, and a thiol group at the three basal vertices to anchor to the FLB. The TDNs are also marked with a redox indicator, Azure A (AA), which allows the direct detection of SARS-CoV-2 spike protein through changes in the current intensity of its electrolysis before and after the biorecognition reaction. The developed sensor can detect SARS-CoV-2 spike protein with a detection limit of 1.74 fg mL-1 directly in nasopharyngeal swab human samples. Therefore, this study offers a new strategy for rapid virus detection since it is versatile enough for different viruses and pathogens.

Rapid and simple viral protein detection by functionalized 2D MoS2/graphene electrochemiluminescence aptasensor.

In this work we present the development of an electrochemiluminescence aptasensor based on electrografting molybdenum disulphide nanosheets functionalized with diazonium salt (MoS2-N2+) upon screen-printed electrodes of graphene (SPEs GPH) for viral proteins detection. In brief, this aptasensor consists of SPEs GPH electrografted with MoS2-N2+ and modified with a thiolated aptamer, which can specifically recognize the target protein analyte. In this case, we have used SARS-CoV-2 spike protein as model protein. Electrochemiluminescence detection was performed by using the [Ru(bpy)3]2+/TPRA (tripropylamine) system, which allows the specific detection of the SARS-CoV-2 spike protein easily and rapidly with a detection limit of 9.74 fg/mL and a linear range from 32.5 fg/mL to 50.0 pg/mL. Moreover, the applicability of the aptasensor has been confirmed by the detection of the protein directly in human saliva samples. Comparing our device with a traditional saliva antigen test, our aptasensor can detect the spike protein even when the saliva antigen test gives a negative result.

A "signal off-on" fluorescence bioassay based on 2D-MoS2-tetrahedral DNA bioconjugate for rapid virus detection.

In this work we present the preparation of a 2D molybdenum disulphide nanosheets (2D-MoS2) and tetrahedral DNA nanostructures (TDNs) bioconjugate, and its application to the development of a bioassay for rapid and easy virus detection. The bioconjugate has been prepared by using TDNs carrying the capture probe labelled with 6-carboxyfluoresceine (6-FAM). As case of study to assess the utility of the assay developed, we have chosen the SARS-CoV-2 virus. Hence, as probe we have used a DNA sequence complementary to a region of the SARS-CoV-2 ORF1ab gene (TDN-ORF-FAM). This 6-FAM labelled capture probe is located on the top vertex of the tetrahedral DNA nanostructure, the three left vertices of TDNs have a thiol group. These TDNs are bounded to 2D-MoS2 surface through the three thiol groups, allowing the capture probe to be oriented to favour the biorecognition reaction with the analyte. This biorecognition resulting platform has finally been challenged to the detection of the SARS-CoV-2 ORF1ab gene sequence as the target model by measuring fluorescence before and after the hybridization event with a detection limit of 19.7fM. Furthermore, due to high sensitivity of the proposed methodology, it has been applied to directly detect the virus in nasopharyngeal samples of infected patients without the need of any amplification step. The developed bioassay has a wide range of applicability since it can be applied to the detection of any pathogen by changing the probe corresponding to the target sequence. Thus, a novel, hands-on strategy for rapid pathogen detection has proposed and has a high potential application value in the early diagnosis of infections causes by virus or bacteria.

Multiplex Portable Biosensor for Bacteria Detection.

An advanced, cost-effective, and portable DNA biosensor capable of detecting multiple bacteria simultaneously has been developed. The biosensor comprises a fast and inexpensive potentiostat that controls the applied potential to a screen-printed electrochemical array platform functionalized with MoS2 flakes and bacterial DNA probes. The current response obtained by à la carte thionine functionalized carbon nanodots (Ty-CDs) is monitored as an electrochemical indicator of the hybridization event. The design of the potentiostat prioritizes achieving an optimal signal-to-noise ratio and incorporates a user-friendly interface compatible with various devices, including computers, mobile phones, and tablets. The device is compact, lightweight, and manufactured at a low cost. The key components of the potentiostat include a data acquisition board capable of analyzing multiple samples simultaneously and a controller board. The results of this study confirm the ability of the multiplex portable biosensor to successfully detect specific bacterial DNA sequences, demonstrating its reliability and superior performance compared with a traditional, more complex, and laboratory-oriented potentiostat.

Bio-Polyethylene Composites Based on Sugar Cane and Curauá Fiber: An Experimental Study.

For the purpose of renewable materials applications, Curauá fiber treated with 5% sodium hydroxide was added to high-density biopolyethylene, using an entirely Brazilian raw material of sugarcane ethanol. Polyethylene grafted with maleic anhydride was used as a compatibilizer. With the addition of curauá fiber, the crystallinity was reduced, possibly due to interactions in the crystalline matrix. A positive thermal resistance effect was observed for the maximum degradation temperatures of the biocomposites. When curauá fiber was added (5% by weight), the morphology showed interfacial adhesion, greater energy storage and damping capacity. Although curauá fiber additions did not affect the yield strength of high-density bio polyethylene, its fracture toughness improved. With the addition of curauá fiber (5% by weight), the fracture strain was greatly reduced to about 52%, the impact strength was also reduced, suggesting a reinforcing effect. Concomitantly, the modulus and the maximum bending stress, as well as the Shore D hardness of the curauá fiber biocomposites (at 3 and 5% by weight), were improved. Two important aspects of product viability were achieved. First, there was no change in processability and, second, with the addition of small amounts of curauá fiber, there was a gain in the specific properties of the biopolymer. The resulting synergies can help ensure more sustainable and environmentally friendly manufacturing of automotive products.

Degradation of Hydrogels Based on Potassium and Sodium Polyacrylate by Ionic Interaction and Its Influence on Water.

Hydrogels are a very useful type of polymeric material in several economic sectors, acquiring great importance due to their potential applications; however, this type of material, similarly to all polymers, is susceptible to degradation, which must be studied to improve its use. In this sense, the present work shows the degradation phenomena of commercial hydrogels based on potassium and sodium polyacrylate caused by the intrinsic content of different types of potable waters and aqueous solutions. In this way, a methodology for the analysis of this type of phenomenon is presented, facilitating the understanding of this type of degradation phenomenon. In this context, the hydrogels were characterized through swelling and FTIR to verify their performance and their structural changes. Likewise, the waters and wastewaters used for the swelling process were characterized by turbidity, pH, hardness, metals, total dissolved solids, electrical conductivity, DLS, Z-potential, and UV-vis to determine the changes generated in the types of waters caused by polymeric degradation and which are the most relevant variables in the degradation of the studied materials. The results obtained suggest a polymeric degradation reducing the swelling capacity and the useful life of the hydrogel; in addition, significant physicochemical changes such as the emergence of polymeric nanoparticles are observed in some types of analyzed waters.

On how the power supply shapes microbial survival.

Understanding how environmental factors affect microbial survival is an important open problem in microbial ecology. Patterns of microbial community structure have been characterized across a wide range of different environmental settings, but the mechanisms generating these patterns remain poorly understood. Here, we use mathematical modelling to investigate fundamental connections between chemical power supply to a system and patterns of microbial survival. We reveal a complex set of interdependences between power supply and distributions of survival probability across microbial habitats, in a case without interspecific resource competition. We also find that different properties determining power supply, such as substrate fluxes and Gibbs energies of reactions, affect microbial survival in fundamentally different ways. Moreover, we show how simple connections between power supply and growth can give rise to complex patterns of microbial survival across physicochemical gradients, such as pH gradients. Our findings show the importance of taking energy fluxes into account in order to reveal fundamental connections between microbial survival and environmental conditions, and to obtain a better understanding of microbial population dynamics in natural environments.

Transfer entropy computation using the Perron-Frobenius operator.

We propose a method for computing the transfer entropy between time series using Ulam's approximation of the Perron-Frobenius (transfer) operator associated with the map generating the dynamics. Our method differs from standard transfer entropy estimators in that the invariant measure is estimated not directly from the data points, but from the invariant distribution of the transfer operator approximated from the data points. For sparse time series and low embedding dimension, the transfer operator is approximated using a triangulation of the attractor, whereas for data-rich time series or higher embedding dimension, we use a faster grid approach. We compare the performance of our methods with existing estimators such as the k nearest neighbors method and kernel density estimation method, using coupled instances of well known chaotic systems: coupled logistic maps and a coupled Rössler-Lorenz system. We find that our estimators are robust against moderate levels of noise. For sparse time series with less than 100 observations and low embedding dimension, our triangulation estimator shows improved ability to detect coupling directionality, relative to standard transfer entropy estimators.

Forcing of late Pleistocene ice volume by spatially variable summer energy.

Changes in Earth's orbit set the pace of glacial cycles, but the role of spatial variability in the insolation forcing of global ice volume remains unknown. Here, we leverage the intrinsic dynamical information in empirical records to show that ice volume responded to summer energy at high northern latitudes, as predicted by Milankovitch theory. However, the external forcing of ice volume encompasses insolation signals with a wide range of orbital frequency content, and cannot be fully accounted for by a unique time series. Southern mid-latitude insolation forcing coincides with the position of the subtropical front and the westerlies, which have been implicated in Quaternary climate changes. Dominant forcing modes at northern mid-latitudes are anti-phased with the canonical Milankovitch forcing, consistent with ice volume sensitivity to latitudinal insolation gradients.

Influence of compatibilizer on the properties of low-density polyethylene/polyamide 6 blends obtained by mechanical recycling of multilayer film waste.

Polymeric wastes have caused increasing environmental problems, mainly in oceans that accumulate large amounts of non-degradable plastic waste. Particularly, waste of polymeric multilayer films for packaging presents low interest for mechanical recycling due to the poor properties and low commercial value of the recycled material generated as polymeric blends. Multilayer films of low-density polyethylene (LDPE) and polyamide 6 (PA6) is a typical material used for packaging applications. The aim of this study was to evaluate the action of the concentration of maleic anhydride grafted polyethylene (PE- g-MA) on the compatibilization of LDPE/PA6 blends generated from mechanical recycling of multilayer films containing both polymers. The action of the PE- g-MA on the properties of the LDPE/PA6 blends was evaluated by tensile tests, optical microscopy, melt flow rate, and scanning electron microscopy. The use of PE- g-MA at 2.5 wt% as a compatibilizer during reactive extrusion of the multilayer films waste has showed the best result for production of the respective recycled LDPE/PA6 blends.

Common species link global ecosystems to climate change: dynamical evidence in the planktonic fossil record.

Common species shape the world around us, and changes in their commonness signify large-scale shifts in ecosystem structure and function. However, our understanding of long-term ecosystem response to environmental forcing in the deep past is centred on species richness, neglecting the disproportional impact of common species. Here, we use common and widespread species of planktonic foraminifera in deep-sea sediments to track changes in observed global occupancy (proportion of sampled sites at which a species is present and observed) through the turbulent climatic history of the last 65 Myr. Our approach is sensitive to relative changes in global abundance of the species set and robust to factors that bias richness estimators. Using three independent methods for detecting causality, we show that the observed global occupancy of planktonic foraminifera has been dynamically coupled to past oceanographic changes captured in deep-ocean temperature reconstructions. The causal inference does not imply a direct mechanism, but is consistent with an indirect, time-delayed causal linkage. Given the strong quantitative evidence that a dynamical coupling exists, we hypothesize that mixotrophy (symbiont hosting) may be an ecological factor linking the global abundance of planktonic foraminifera to long-term climate changes via the relative extent of oligotrophic oceans.

Modeling the downward transport of (210)Pb in Peatlands: Initial Penetration-Constant Rate of Supply (IP-CRS) model.

The vertical distribution of (210)Pb is commonly used to date peat deposits accumulated over the last 100-150 years. However, several studies have questioned this method because of an apparent post-depositional mobility of (210)Pb within some peat profiles. In this study, we introduce the Initial Penetration­Constant Rate of Supply (IP-CRS) model for calculating ages derived from 210Pb profiles that are altered by an initial migration of the radionuclide. This new, two-phased, model describes the distribution of atmospheric-derived (210)Pb ((210)Pbxs) in peat taking into account both incorporation of (210)Pb into the accumulating peat matrix as well as an initial flushing of (210)Pb through the uppermost peat layers. The validity of the IP-CRS model is tested in four anomalous (210)Pb peat records that showed some deviations from the typical exponential decay profile not explained by variations in peat accumulation rates. Unlike the most commonly used (210)Pb-dating model (Constant Rate of Supply (CRS)), the IP-CRS model estimates peat accumulation rates consistent with typical growth rates for peatlands from the same areas. Confidence in the IP-CRS chronology is also provided by the good agreement with independent chronological markers (i.e. (241)Am and (137)Cs). Our results showed that the IP-CRS can provide chronologies from peat records where (210)Pb mobility is evident, being a valuable tool for studies reconstructing past environmental changes using peat archives during the Anthropocene.

Modeling the connection between primary and metastatic tumors.

We put forward a model for cancer metastasis as a migration phenomenon between tumor cell populations coexisting and evolving in two different habitats. One of them is a primary tumor and the other one is a secondary or metastatic tumor. The evolution of the different cell phenotype populations in each habitat is described by means of a simple quasispecies model allowing for a cascade of mutations between the different phenotypes in each habitat. The cell migration event is supposed to be unidirectional and take place continuously in time. The possible clinical outcomes of the model depending on the parameter space are analyzed and the effect of the resection of the primary tumor is studied.

Bright solitary waves in malignant gliomas.

We put forward a nonlinear wave model describing the fundamental dynamical features of an aggressive type of brain tumors. Our model accounts for the invasion of normal tissue by a proliferating and propagating rim of active glioma cancer cells in the tumor boundary and the subsequent formation of a necrotic core. By resorting to numerical simulations, phase space analysis, and exact solutions we prove that bright solitary tumor waves develop in such systems. Possible implications of our model as a tool to extract relevant patient specific tumor parameters in combination with standard preoperative clinical imaging are also discussed.

Estudio del polimorfismo leu33/pro33 del receptor glicoproteico plaquetario IIIa (PIA) y su relación con la reestenosis postangioplastia coronaria con stent en una población argentina / Study of the relationship between the leu33/pro33 polymorphism of platelet glycoprotein receptor IIIa and post-coronary angioplasty in-stent restenosis in an argentinian population

Introducción: En pacientes con el polimorfismo del receptor plaquetario IIIa (PIA2), más en homocigotos PIA2/A2, se observó un porcentaje mayor de reestenosis postangioplastia coronaria con stent que en los pacientes PIA1/A1 o normales. Objetivo: Determinar la presencia del alelo polimórfico PIA2 en pacientes con reestenosis postangioplastia con stent en una población argentina; evaluar porcentaje de PIA2/A2 entre los reestenosadores y determinar la penetrancia del alelo polimórfico PIA2 en una población de nuestro país sin antecedentes coronarios. Métodos: Se evaluaron 45 pacientes, que integraron tres poblaciones. Díez sin antecedentes coronarios (9 hombres, 30 ± 5 años). Dieciseis pacientes con angioplastia (13 hombres, 62 ± 11 años) con control angiográfico a los 7 ± 1 mes que no evidenció reestenosis y 19 con reestenosis postangioplastia (16 hombres, 60 ± 12 años). Se consideró reestenosis una lesión mayor del 50 por ciento en el reestudio. Se realizó la reacción en cadena de la polimerasa en busca de la presencia del alelo PIA2. Se utilizó la prueba de Fischer para comparaciones. Resultados: De los 19 pacientes reestenosadores, 9 presentaron el alelo A2 (47 por ciento); de los 16 pacientes no reestenosadores presentaron el alelo A2 sólo el 13 por ciento (p < 0,04). De los 10 pacientes sin antecedentes se detectó un solo A2 (10 por ciento). Sólo 2 pacientes eran homocigotos A2/A2 y se encontraron en el grupo reestenosador. Conclusión: La presencia del alelo A2 (PIA1/A2 o PIA2/A2) fue significativamente mayor en los pacientes con reestenosis, lo cual podría ser un predictor de reestenosis postangioplastia con stent y su detección previa podría tener implicaciones terapéuticas. (AU)

Estudio del polimorfismo leu33/pro33 del receptor glicoproteico plaquetario IIIa (PIA) y su relación con la reestenosis postangioplastia coronaria con stent en una población argentina / Study of the relationship between the leu33/pro33 polymorphism of platelet glycoprotein receptor IIIa and post-coronary angioplasty in-stent restenosis in an argentinian population

Introducción: En pacientes con el polimorfismo del receptor plaquetario IIIa (PIA2), más en homocigotos PIA2/A2, se observó un porcentaje mayor de reestenosis postangioplastia coronaria con stent que en los pacientes PIA1/A1 o normales. Objetivo: Determinar la presencia del alelo polimórfico PIA2 en pacientes con reestenosis postangioplastia con stent en una población argentina; evaluar porcentaje de PIA2/A2 entre los reestenosadores y determinar la penetrancia del alelo polimórfico PIA2 en una población de nuestro país sin antecedentes coronarios. Métodos: Se evaluaron 45 pacientes, que integraron tres poblaciones. Díez sin antecedentes coronarios (9 hombres, 30 ± 5 años). Dieciseis pacientes con angioplastia (13 hombres, 62 ± 11 años) con control angiográfico a los 7 ± 1 mes que no evidenció reestenosis y 19 con reestenosis postangioplastia (16 hombres, 60 ± 12 años). Se consideró reestenosis una lesión mayor del 50 por ciento en el reestudio. Se realizó la reacción en cadena de la polimerasa en busca de la presencia del alelo PIA2. Se utilizó la prueba de Fischer para comparaciones. Resultados: De los 19 pacientes reestenosadores, 9 presentaron el alelo A2 (47 por ciento); de los 16 pacientes no reestenosadores presentaron el alelo A2 sólo el 13 por ciento (p < 0,04). De los 10 pacientes sin antecedentes se detectó un solo A2 (10 por ciento). Sólo 2 pacientes eran homocigotos A2/A2 y se encontraron en el grupo reestenosador. Conclusión: La presencia del alelo A2 (PIA1/A2 o PIA2/A2) fue significativamente mayor en los pacientes con reestenosis, lo cual podría ser un predictor de reestenosis postangioplastia con stent y su detección previa podría tener implicaciones terapéuticas.