RESUMEN

Stressed soft materials commonly present viscoelastic signatures in the form of power-law or exponential decay. Although exponential responses are the most common, power-law time dependencies arise peculiarly in complex soft materials such as living cells. Understanding the microscale mechanisms that drive rheologic behaviors at the macroscale shall be transformative in fields such as material design and bioengineering. Using an elastic network model of macromolecules immersed in a viscous fluid, we numerically reproduce those characteristic viscoelastic relaxations and show how the microscopic interactions determine the rheologic response. The macromolecules, represented by particles in the network, interact with neighbors through a spring constant k and with fluid through a non-linear drag regime. The dissipative force is given by γvα, where v is the particle's velocity, and γ and α are mesoscopic parameters. Physically, the sublinear regime of the drag forces is related to micro-deformations of the macromolecules, while α ≥ 1 represents rigid cases. We obtain exponential or power-law relaxations or a transitional behavior between them by changing k, γ, and α. We find that exponential decays are indeed the most common behavior. However, power laws may arise when forces between the macromolecules and the fluid are sublinear. Our findings show that in materials not too soft not too elastic, the rheological responses are entirely controlled by α in the sublinear regime. More specifically, power-law responses arise for 0.3 ⪅ α ⪅ 0.45, while exponential responses for small and large values of α, namely, 0.0 ⪅ α ⪅ 0.2 and 0.55 ⪅ α ⪅ 1.0.

Asunto(s)

Ingeniería Biomédica , Viscosidad , Reología

RESUMEN

Gullies are a major threat to ecosystems, potentially leading to land degradation, groundwater depletion, crop loss, debris flow, and desertification. Gullies are also characterized by having a fast development and turning into primary sediment sources. Despite their impact, we have but scarce understanding of how gully erosion evolves and how to model it. In this paper, we propose a new gully erosion model that is based on the classical premise of net shear stress, i.e., hydraulic shear stress minus critical (resistant) shear stress, to calculate detachment rates. In order to calculate hydraulic shear stress, we developed a new equation derived from the principle of minimum cross-entropy; it was validated with laboratory measures from the literature with a Nash-Sutcliffe Efficiency of 0.95. Soil samples were analysed in the laboratory to assess critical shear stress and other soil properties. The novel gully erosion model was implemented in three gully impacted locations with catchment areas ranging from 10-2 to 10+1 ha. To assess channel geometry and eroded volumes, we used Unmanned Aerial Vehicle and Structure-from-Motion technique. The model successfully estimated long-term erosion rates, its efficiency was 0.77, and it is recommended for catchments up to 8 ha. Therefore, the new model provides planners and stakeholders with a tool to assess gully erosion, sediment yield and geometry in most areas.

Asunto(s)

Conservación de los Recursos Naturales , Ecosistema , Conservación de los Recursos Naturales/métodos , Entropía , Suelo

RESUMEN

We investigate the magnetic nanoparticles hyperthermia in a non-adiabatic and radiating process through the calorimetric method. Specifically, we propose a theoretical approach to magnetic hyperthermia from a thermodynamic point of view. To test the robustness of the approach, we perform hyperthermia experiments and analyse the thermal behavior of magnetite and magnesium ferrite magnetic nanoparticles dispersed in water submitted to an alternating magnetic field. From our findings, besides estimating the specific loss power value from a non-adiabatic and radiating process, thus enhancing the accuracy in the determination of this quantity, we provide physical meaning to a parameter found in literature that still remained not fully understood, the effective thermal conductance, and bring to light how it can be obtained from experiment. In addition, we show our approach brings a correction to the estimated experimental results for specific loss power and effective thermal conductance, thus demonstrating the importance of the heat loss rate due to the thermal radiation in magnetic hyperthermia.

RESUMEN

OBJECTIVE: Identify risk factors for microcephaly and evaluate historical trends of microcephaly and arboviruses to recognize patterns and anomalies that indicate the beginning of the microcephaly epidemic associated with Zika infection. METHODS: The head circumferences of 62,298 newborns was analyzed to identify cases of microcephaly between 2014 and 2017. We compared the groups of newborns with normal head circumferences and those with microcephaly to identify risk factors. A time series with the incidences of microcephaly was analyzed to assess the appearance of anomalous values in order to identify the beginning of the microcephaly epidemic. Data on the incidence of dengue fever was used to develop a control chart, aiming to identify changes in incidence and seasonality that could suggest the circulation of a new arbovirus. FINDINGS: Premature newborns, children of mothers under 20 years of age and those born in 2014 and 2015 had a higher risk of microcephaly. Three quarters with anomalous incidences of microcephaly were identified, the first in 2014 and the others in 2015. The dengue fever epidemic curve in 2013 shows persistence of high incidences in atypical periods, suggesting the entry of a new virus in the 3rd and 4th quarters. CONCLUSIONS: These findings represent epidemiological evidence of the existence of cases of Zika virus between the 2nd quarter of 2013 and the beginning of 2014. The results add new elements to understanding the Zika virus epidemic in the Americas.

Asunto(s)

Epidemias , Microcefalia/epidemiología , Complicaciones Infecciosas del Embarazo/epidemiología , Infección por el Virus Zika/epidemiología , Adulto , Américas/epidemiología , Arbovirus/aislamiento & purificación , Brasil/epidemiología , Estudios Transversales , Dengue/epidemiología , Femenino , Humanos , Incidencia , Recién Nacido , Masculino , Microcefalia/virología , Embarazo , Complicaciones Infecciosas del Embarazo/virología , Factores de Riesgo , Adulto Joven , Virus Zika/aislamiento & purificación , Infección por el Virus Zika/virología

RESUMEN

The aim of this study was to evaluate the combined use of different chemical (albendazole, ivermectin, glycerine and Vaseline) and biological (Monacrosporium thaumasium) compounds in the control of Ancylostoma caninum. Infective larvae of A. caninum were obtained from coprocultures of positive faeces from naturally infected dogs. We used 1% ivermectin, 1% albendazole, 100% glycerine, 100% Vaseline and an isolate of the nematophagous fungus M. thaumasium (NF34), alone or in combinations. Next, an experimental test was set up with 16 groups in microtubes, with a 24-h interaction. The groups (G1 to G15) that contained any chemical or biological compound (NF34) and/or their combined use (chemical + biological) showed a difference in relation to the control group, except G5 - Vaseline 100% without combinations. It was concluded that, even on an experimental basis, the combined use of anthelmintic drugs with biological control was efficient; however, more studies must be carried out in order to elucidate the synergistic action between chemical and biological compounds to be used in the effective control of hookworms in the future.

Asunto(s)

Ancylostomatoidea/efectos de los fármacos , Antihelmínticos/farmacología , Productos Biológicos/farmacología , Enfermedades de los Perros/tratamiento farmacológico , Infecciones por Uncinaria/veterinaria , Animales , Ascomicetos , Productos Biológicos/química , Enfermedades de los Perros/parasitología , Perros , Sinergismo Farmacológico , Infecciones por Uncinaria/tratamiento farmacológico , Larva/efectos de los fármacos

RESUMEN

Biowaste material is a good candidate for the production of energy in urban territories. The presence of undesirable or constituents mixed with the biowaste collected by municipalities makes it difficult to recycle organic matter of sufficient quality for agricultural uses. Methane production is particularly attractive for energy recovery notably because this energy vector can be distributed using the grid already in place for natural gas in many cities. Depending on the origin and biochemical composition of biowaste, methane can be produced using thermochemical (gasification then syngas methanation) or biological processes (anaerobic digestion). The objective of this work was to characterize the ability of biowaste to be used as a feedstock for anaerobic digestion. Based on considerations such as the quantities produced and the availability, four categories of biowaste produced in the city of Lyon were identified as potential key resources: Garden biowaste (GBW), restauration biowaste (RBW), household biowaste (HBW) and supermarkets biowaste (SMBW). Representative samples were taken from the sites of production and analyzed for parameters including biomethane potential (BMP). Each sample was then fractioned by leaching and the distribution of the BMP between the particulate fraction and the readily soluble fraction was assessed. GBW organic matter exhibited high hemicellulose content (over 81% of VS) and a low BMP which was very poorly distributed into its soluble fraction (2 NL·kgTS-1). RBW, HBW and SMBW showed a much higher BMP with a strong distribution in the soluble fraction (100 NL·kgTS-1). Plastic materials were found to account for up to 40% of the mass of SMBW sample. Altogether, GBW was identified as non-favorable for anaerobic digestion and recommended rather for thermochemical conversion. HBW, RBW and SMBW revealed adapted to anaerobic. Pulping was shown to be applicable in order to convert the 3 biowaste materials into a pumpable slurry with high biomethane potential.

Asunto(s)

Metano/metabolismo , Anaerobiosis , Reactores Biológicos , Ciudades , Reciclaje , Eliminación de Residuos , Agua

Asunto(s)

Animales , Duddingtonia , Nematodos , Infecciones por Nematodos , Control Biológico de Vectores , Heces

RESUMEN

Lymphoplasmacytic inflammation associated with bornavirus N protein occurs in the epicardial ganglia, myocardium and endocardium of birds diagnosed with proventricular dilatation disease (PDD). These pathological findings suggest that sudden death in psittacine birds might stem from cardiac compromise due to parrot bornavirus (PaBV) infection. Therefore, we investigated cardiac lesions in cases of PDD, searching databases from 1988 to 2019, and reviewed three experimental studies of PaBV infection. Fifty cases of PDD in birds infected naturally with PaBV and 27 cases of PDD in birds infected experimentally with PaBV (all having descriptions of inflammatory cardiac lesions) were reviewed. For each case, five regions of the heart were evaluated by light microscopy and immunohistochemistry (IHC). These regions were the epicardial ganglia/nerves, the endocardium, the myocardium, the Purkinje fibres and the great vessels. Sudden death was documented in 17/50 naturally infected cases, while 23/50 had digestive signs, and only 12/50 had neurological signs. Grossly, only five naturally-infected and five experimentally-infected cases had cardiomegaly or hydropericardium. Epicardial ganglioneuritis was the most consistent microscopical finding in natural (46/50) and experimental cases (26/27), followed by myocarditis (34/50) for naturally-infected and endocarditis for experimentally-infected birds (6/27). PaBV-2 antigen was detected most frequently by IHC in the epicardial ganglia (54/77) compared with the other tissues. This retrospective study demonstrates the presence of PaBV protein and inflammation in the heart of birds infected with PaBV and suggests a link between PaBV and cardiac disease and sudden death in psittacine birds.

Asunto(s)

Enfermedades de las Aves/patología , Endocardio/patología , Infecciones por Mononegavirales/veterinaria , Miocardio/patología , Pericardio/patología , Animales , Enfermedades de las Aves/virología , Bornaviridae , Endocardio/virología , Corazón/virología , Infecciones por Mononegavirales/patología , Pericardio/virología , Psittaciformes , Estudios Retrospectivos

Asunto(s)

Duddingtonia , Nematodos , Infecciones por Nematodos , Animales , Heces , Control Biológico de Vectores

RESUMEN

Chagas disease (CD) is a neglected parasitic condition endemic in the Americas caused by Trypanosoma cruzi. Patients present an acute phase that may or not be symptomatic, followed by lifelong chronic stage, mostly indeterminate, or with cardiac and/or digestive progressive lesions. Benznidazole (BZ) and nifurtimox are the only drugs approved for treatment but not effective in the late chronic phase and many strains of the parasite are naturally resistant. New alternative therapy is required to address this serious public health issue. Repositioning and combination represent faster, and cheaper trial strategies encouraged for neglected diseases. The effect of imatinib (IMB), a tyrosine kinase inhibitor designed for use in neoplasias, was assessed in vitro on T. cruzi and mammalian host cells. In comparison with BZ, IMB was moderately active against different strains and forms of the parasite. The combination IMB + BZ in fixed-ratio proportions was additive. Novel 14 derivatives of IMB were screened and a 3,2-difluoro-2-phenylacetamide (3e) was as potent as BZ on T. cruzi but had low selectivity index. The results demonstrate the importance of phenotypic assays, encourage the improvement of IMB derivatives to reach selectivity and testify to the use of repurposing and combination in drug screening for CD.

Asunto(s)

Enfermedad de Chagas/tratamiento farmacológico , Reposicionamiento de Medicamentos , Mesilato de Imatinib/farmacología , Nitroimidazoles/farmacología , Tripanocidas/farmacología , Trypanosoma cruzi/efectos de los fármacos , Animales , Línea Celular , Quimioterapia Combinada , Fibroblastos , Ratones

RESUMEN

Zymomonas mobilis has long attracted attention owing to its capacity to ferment hexose to ethanol. From a taxonomic viewpoint, Z. mobilis is a unique species of the genus Zymomonas, separated into three subspecies, Z. mobilis subsp. mobilis, Z. mobilis subsp. pomaceae and Z. mobilis subsp. francensis on the basis of physiological tests, which are often unreliable owing to the genetic proximity among these species. Currently, the use of molecular techniques is more appropriate for identification of these bacterial subspecies. In this study, the 32 strains of Z. mobilis present in the UFPEDA bacterial collection were characterized using molecular techniques, such as sequencing of the 16S rDNA gene and its theoretical restriction profile, classifying them as members of the subspecies, Z. mobilis subsp. mobilis. In addition, anaerobic cultivations were performed, which showed the biological diversity of the strains in terms of growth, sugar consumption and ethanol production. From these results, it was possible to identify the strain Z-2-80 as a promising bacterium for use in the fermentation process. SIGNIFICANCE AND IMPACT OF THE STUDY: Zymomonas mobilis is a bacterium of great relevance to biotechnology, owing to its capacity to ferment hexose to ethanol. On a molecular basis, 32 isolates were identified as Z. mobilis subsp. mobilis. However, intraspecific diversity was identified when these were grown under strictly anaerobic conditions. The results obtained from this study suggest a strain of Z. mobilis as an alternative for use in the fermentation process.

Asunto(s)

Reactores Biológicos/microbiología , ADN Bacteriano/genética , Etanol/metabolismo , Zymomonas/clasificación , Zymomonas/metabolismo , Anaerobiosis , Brasil , ADN Ribosómico/genética , Fermentación , Hexosas/metabolismo , ARN Ribosómico 16S/genética , Zymomonas/genética , Zymomonas/aislamiento & purificación

RESUMEN

A 17-year-old female emu (Dromaius novaehollandiae) was presented for clinical evaluation due to a 3-week history of anorexia and progressive weight loss. The emu died after sedation. At necropsy examination, the ovary and the majority of the oviduct were effaced by a multinodular cystic mass and accompanied by 6 l of coelomic effusion. Histopathology revealed a neoplasm composed of well-differentiated, poorly organized tissues derived from ectoderm, mesoderm and endoderm. Tissues within the neoplasm expressed glial fibrillary acidic protein, desmin and cytokeratins AE1/AE3, respectively, confirming the diagnosis of teratocarcinoma.

Asunto(s)

Dromaiidae , Neoplasias Ováricas/veterinaria , Teratocarcinoma/veterinaria , Animales , Femenino

RESUMEN

Metronidazole (Mtz) is a commercial broad-spectrum nitroimidazolic derivative with relevant antimicrobial activity and relative safety profile. Therefore, it is fair to consider Mtz a candidate for drug repurposing for other neglected conditions such as Chagas disease (CD), a parasitic pathology caused by Trypanosoma cruzi. CD is treated only with benznidazole (Bz) and nifurtimox, both introduced in clinics decades ago despite important limitations, including low efficacy on the later disease stage (chronic form) and severe side effects. New cheap and fast alternative treatments for CD are needed, thus the repurposing of Mtz was assessed in vitro and in vivo in mono- and combined therapy. In vitro assays demonstrated EC50>200µM for Mtz, while for Bz the values ranged from 2.51µM (intracellular forms) to 11.5µM (bloodstream trypomastigotes). When both drugs were combined in fixed-ratio proportions, Mtz promoted Bz potency (lower EC50 values). In vivo toxicity assays for Mtz in mice showed no adverse effects neither histopathological alterations up to 2000mg/kg. Regarding experimental T. cruzi infection, Bz 100mg/kg suppressed parasitemia while Mtz (up to 1000mg/kg) in monotherapy did not, but prolonged animal survival at 250 and 500 regimen doses. The combination of both drugs (Bz 10+Mtz 250) prevented mortality (70%) besides protected against electric cardiac alterations triggered by the parasite infection. Although not able to reduce parasite load, the combination therapy prevented animal mortality; this was possibly due to a protection of the electric cardiac physiology that is normally altered in experimental infection of T. cruzi. It also suggested that the interaction with Mtz could have improved the pharmacokinetics of Bz. Our study emphasizes the importance of drug repurposing and combined therapy for CD to contribute to alternative therapies for this neglected and silent pathology.

Asunto(s)

Antiprotozoarios/farmacología , Enfermedad de Chagas/tratamiento farmacológico , Metronidazol/farmacología , Miocitos Cardíacos/parasitología , Nitroimidazoles/farmacología , Trypanosoma cruzi , Animales , Antiprotozoarios/administración & dosificación , Antiprotozoarios/química , Antiprotozoarios/uso terapéutico , Células Cultivadas , Quimioterapia Combinada , Metronidazol/administración & dosificación , Metronidazol/química , Metronidazol/uso terapéutico , Ratones , Estructura Molecular , Miocitos Cardíacos/efectos de los fármacos , Nitroimidazoles/administración & dosificación , Nitroimidazoles/química , Nitroimidazoles/uso terapéutico

RESUMEN

Two-dimensional systems of inverse patchy colloids modeled as disks with a central charge and having their surface decorated with oppositely pointlike charged patches are investigated using molecular dynamics simulations. The self-assembly of the patchy colloids leads to diverse ground state configurations ranging from crystalline arrangements of monomers to linear clusters, ramified linear clusters and to percolated configurations. Two structural phase diagrams are constructed: (1) as a function of the net charge and area fraction, and (2) as a function of the net charge and the range of the pair interaction potential. An interesting reentrant percolation transition is obtained as a function of the net charge of the colloids. We identify distinct mechanisms that lead to the percolation transition.

RESUMEN

Accumulated sludge in polishing (maturation) ponds reduces the hydraulic retention time (smaller useful volume), and this could potentially lead to a decrease in performance. However, settled biomass, present in the sediments, can contribute to nitrogen removal by different mechanisms such as nitrification and denitrification. This study investigated the influence of the bottom sludge present in a shallow maturation pond treating the effluent from an anaerobic reactor on the nitrification and denitrification processes. Nitrification and denitrification rates were determined in sediment cores by applying ammonia pulses. Environmental conditions in the medium were measured and bacteria detected and quantified by real-time polymerase chain reaction (real-time PCR). The pond showed daily cycles of mixing and stratification and most of the bacteria involved in nitrogen removal decreased in concentration from the upper to the lower part of the sludge layer. The results indicate that denitrifiers, nitrifiers and anammox bacteria coexisted in the sludge, and thus different metabolic pathways were involved in ammonium removal in the system. Therefore, the sediment contributed to nitrogen removal, even with a decrease in the hydraulic retention time in the pond due to the volume occupied by the sludge.

Asunto(s)

Nitrógeno/análisis , Aguas del Alcantarillado/química , Eliminación de Residuos Líquidos/métodos , Contaminantes Químicos del Agua/análisis , Reactores Biológicos , Brasil , Desnitrificación , Estanques

RESUMEN

Chagas disease is a life-threatening infection caused by a variety of genetically diverse strains of the protozoan parasite Trypanosoma cruzi The current treatment (benznidazole and nifurtimox) is unsatisfactory, and potential alternatives include inhibitors of sterol 14α-demethylase (CYP51), the cytochrome P450 enzyme essential for the biosynthesis of sterols in eukaryotes and the major target of clinical and agricultural antifungals. Here we performed a comparative investigation of two protozoon-specific CYP51 inhibitors, VNI and its CYP51 structure-based derivative VFV, in the murine models of infection caused by the Y strain of T. cruzi The effects of different treatment regimens and drug delivery vehicles were evaluated in animals of both genders, with benznidazole serving as the reference drug. Regardless of the treatment scheme or delivery vehicle, VFV was more potent in both genders, causing a >99.7% peak parasitemia reduction, while the VNI values varied from 91 to 100%. Treatments with VNI and VFV resulted in 100% animal survival and 0% natural relapse after the end of therapy, though, except for the 120-day treatment schemes with VFV, relapses after three cycles of immunosuppression were observed in each animal group, and quantitative PCR analysis revealed a very light parasite load in the blood samples (sometimes below or near the detection limit, which was 1.5 parasite equivalents/ml). Our studies support further investigations of this class of compounds, including their testing against other T. cruzi strains and in combination with other drugs.

Asunto(s)

Inhibidores de 14 alfa Desmetilasa/farmacología , Enfermedad de Chagas/tratamiento farmacológico , Sistema Enzimático del Citocromo P-450/química , Imidazoles/farmacología , Oxadiazoles/farmacología , Tripanocidas/farmacología , Trypanosoma cruzi/efectos de los fármacos , Inhibidores de 14 alfa Desmetilasa/química , Animales , Enfermedad de Chagas/inmunología , Enfermedad de Chagas/parasitología , Ciclofosfamida/efectos adversos , Sistema Enzimático del Citocromo P-450/genética , Sistema Enzimático del Citocromo P-450/metabolismo , Modelos Animales de Enfermedad , Esquema de Medicación , Femenino , Expresión Génica , Humanos , Imidazoles/química , Inmunosupresores/efectos adversos , Masculino , Ratones , Modelos Moleculares , Nitroimidazoles/farmacología , Oxadiazoles/química , Carga de Parásitos , Recurrencia , Análisis de Supervivencia , Tripanocidas/química , Trypanosoma cruzi/enzimología , Trypanosoma cruzi/genética , Trypanosoma cruzi/crecimiento & desarrollo

RESUMEN

The shape and size of nanoparticles are important parameters affecting their biodistribution, bioactivity, and toxicity. The high-throughput characterisation of the nanoparticle shape in dispersion is a fundamental prerequisite for realistic in vitro and in vivo evaluation, however, with routinely available bench-top optical characterisation techniques, it remains a challenging task. Herein, we demonstrate the efficacy of a single particle extinction and scattering (SPES) technique for the in situ detection of the shape of nanoparticles in dispersion, applied to a small library of anisotropic gold particles, with a potential development for in-line detection. The use of SPES paves the way to the routine quantitative analysis of nanoparticles dispersed in biologically relevant fluids, which is of importance for the nanosafety assessment and any in vitro and in vivo administration of nanomaterials.

RESUMEN

The range of possible nanostructures is so large and continuously growing, that collating and unifying the knowledge connected to them, including their biological activity, is a major challenge. Here we discuss a concept that is based on the connection of microscopic features of the nanomaterials to their biological impacts. We also consider what would be necessary to identify the features that control their biological interactions, and make them resemble each other in a biological context.

RESUMEN

What are the necessary ingredients for log-periodicity to appear in the dynamics of a random walk model? Can they be subtle enough to be overlooked? Previous studies suggest that long-range damaged memory and negative feedback together are necessary conditions for the emergence of log-periodic oscillations. The role of negative feedback would then be crucial, forcing the system to change direction. In this paper we show that small-amplitude log-periodic oscillations can emerge when the system is driven by positive feedback. Due to their very small amplitude, these oscillations can easily be mistaken for numerical finite-size effects. The models we use consist of discrete-time random walks with strong memory correlations where the decision process is taken from memory profiles based either on a binomial distribution or on a delta distribution. Anomalous superdiffusive behavior and log-periodic modulations are shown to arise in the large time limit for convenient choices of the models parameters.