Generalized hydrodynamics of a dilute finite-sized particles suspension: Dynamic viscosity

We present a mesoscopic hydrodynamic description of the dynamics of colloidal suspensions. We consider the system as a gas of Brownian particles suspended in a Newtonian heat bath subjected to stationary non-equilibrium conditions imposed by a velocity field. Using results already obtained in previous studies in the field by means of a generalized Fokker-Planck equation, we obtain a set of coupled differential equations for the local diffusion current and the evolution of the total stress tensor. We find that the dynamic shear viscosity of the system contains contributions arising from the finite size of the particles.Comment: To appear in Physical Review

Uncertainty in Model Predictions of Vibrio Vulnificus Response to Climate Variability and Change: A Chesapeake Bay Case Study

The effect that climate change and variability will have on waterborne bacteria is a topic of increasing concern for coastal ecosystems, including the Chesapeake Bay. Surface water temperature trends in the Bay indicate a warming pattern of roughly 0.3-0.4 C per decade over the past 30 years. It is unclear what impact future warming will have on pathogens currently found in the Bay, including Vibrio spp. Using historical environmental data, combined with three different statistical models of Vibrio vulnificus probability, we explore the relationship between environmental change and predicted Vibrio vulnificus presence in the upper Chesapeake Bay. We find that the predicted response of V. vulnificus probability to high temperatures in the Bay differs systematically between models of differing structure. As existing publicly available datasets are inadequate to determine which model structure is most appropriate, the impact of climatic change on the probability of V. vulnificus presence in the Chesapeake Bay remains uncertain. This result points to the challenge of characterizing climate sensitivity of ecological systems in which data are sparse and only statistical models of ecological sensitivity exist

A BK (Slo1) channel journey from molecule to physiology

Calcium and voltage-activated potassium (BK) channels are key actors in cell physiology, both in neuronal and non-neuronal cells and tissues. Through negative feedback between intracellular Ca2+ and membrane voltage, BK channels provide a damping mechanism for excitatory signals. Molecular modulation of these channels by alternative splicing, auxiliary subunits and post-translational modifications showed that these channels are subjected to many mechanisms that add diversity to the BK channel ́ subunit gene. This complexity of interactions modulates BK channel gating, modifying the energetic barrier of voltage sensor domain activation and channel opening. Regions for voltage as well as Ca2+ sensitivity have been identified, and the crystal structure generated by the 2 RCK domains contained in the C-terminal of the channel has been described. The linkage of these channels to many intracellular metabolites and pathways, as well as their modulation by extracellular natural agents, has been found to be relevant in many physiological processes. This review includes the hallmarks of BK channel biophysics and its physiological impact on specific cells and tissues, highlighting its relationship with auxiliary subunit expression.Facultad de Ciencias Exacta

Caracterización hidrogeoquímica de los manantiales del área geotermal de Ixtapan de la Sal-Tonatico (México)

La composición química del agua subterránea es el resultado de continuos procesos de interacción entre el agua de precipitación, que se infiltra en el terreno, y los minerales presentes en las rocas por donde circula. Parte de las características químicas del agua son adquiridas en la zona no saturada y otras más a lo largo de su recorrido dentro de la zona saturada, hasta donde pueden ser captadas o bien emerger como agua de manantial. Estos últimos según sus características, puede ser empleados para consumo humano, como generadores de energía o bien para fines recreativos, como es el caso de los manantiales termales de Ixtapan de la Sal y Tonatico. Los estudios hidrogeoquímicos de manantiales termales han permitido ampliar el conocimiento del origen, edad, composición físico-química de las aguas, de las condiciones de recarga y posibles mezclas de agua, así como identificar los procesos que tienen lugar en el acuífero y que permiten obtener una visión más completa del comportamiento del acuífero. También permiten deducir las características de la roca, composición mineralógica, textura, porosidad, grado de alteración, fracturación y compactación, tiempo de residencia o de contacto, temperatura y presión..

Synthesis of Spherical 4R Mechanism for Path Generation using Differential Evolution

The problem of path generation for the spherical 4R mechanism is solved using the Differential Evolution algorithm (DE). Formulas for the spherical geodesics are employed in order to obtain the parametric equation for the generated trajectory. Direct optimization of the objective function gives the solution to the path generation task without prescribed timing. Therefore, there is no need to separate this task into two stages to make the optimization. Moreover, the order defect problem can be solved without difficulty by means of manipulations of the individuals in the DE algorithm. Two examples of optimum synthesis showing the simplicity and effectiveness of this approach are included.Comment: Submitted to Mechanism and Machine Theor

Variaciones en el ph de la rizosfera y en el porcentaje de materia seca de vicia sativa al aplicar dos fuentes fosfatadas de baja solubilidad en un andisol del departamento de nariño, colombia

En el estudio se utilizaron seis tratamientos: el testigo (T0), sin fuentes fosfatadas (T1) y con adiciones de 25 y 50 kg/ha de P como fosforita Huila (T2 y T3) y calfós (T4 y T5). Los cambios generados por la raíz se evaluaron utilizando la solución nutritiva de Marschner Römheld y Ossenberg-Neuhaus, acondicionada con agar. El porcentaje de materia seca parcial de Vicia sativa se incrementó significativamente al aplicar 25 y 50 kg/ha de P como fosforita Huila (T2 y T3) y calfos (T5 y T6) en la localidad de Genoy. El pH de la solución agarizada sufrió disminuciones significativas a través del tiempo especialmente en los tratamientos T3 y T2.Palabras claves: pH rizosférico, Vicia sativa, Papilionoidea, fuentes fosfatadas, solubilida

Long-term results between interval surgery and follow-up after percutaneous cholecystostomy: a retrospective cohort study

Introduction: Although cholecystectomy is the treatment of choice for acute cholecystitis (AC), in patients with high surgical risk percutaneous cholecystostomy (PC) is chosen in some cases. The aim of this report is to follow up these patients and evaluate biliary recurrences after PC. Methods: A descriptive retrospective study was carried out in a third level hospital from August 2005 to December 2014. All patients diagnosed with acute lithiasis cholecystitis who were indicated as initial treatment with antibiotic therapy and PC echo-guided were included. Patients requiring emergent cholecystectomy during hospital and those who died during the AC episode were excluded. After hospital discharge, the patients were divided into two groups group 1 (interval cholecystectomy) and group 2 (no surgery). Results: From the 86 healed patients, there were 8 losses in the follow-up, so 78 patients were analyzed group 1 (n = 12) and group 2 (n = 66

Innovative Three-Step Microwave-Promoted Synthesis of N-Propargyltetrahydroquinoline and 1,2,3-Triazole Derivatives as a Potential Factor Xa (FXa) Inhibitors: Drug Design, Synthesis, and Biological Evaluation

The coagulation cascade is the process of the conversion of soluble fibrinogen to insoluble fibrin that terminates in production of a clot. Factor Xa (FXa) is a serine protease involved in the blood coagulation cascade. Moreover, FXa plays a vital role in the enzymatic sequence which ends with the thrombus production. Thrombosis is a common causal pathology for three widespread cardiovascular syndromes: acute coronary syndrome (ACS), venous thromboembolism (VTE), and strokes. In this research a series of N-propargyltetrahydroquinoline and 1,2,3-triazole derivatives as a potential factor Xa (FXa) inhibitor were designed, synthesized, and evaluated for their FXa inhibitor activity, cytotoxicity activity and coagulation parameters. Rational design for the desired novel molecules was performed through protein-ligand complexes selection and ligand clustering. The microwave-assisted synthetic strategy of selected compounds was carried out by using Ullmann-Goldberg, N-propargylation, Mannich addition, Friedel-Crafts, and 1,3-dipolar cycloaddition type reactions under microwave irradiation. The microwave methodology proved to be an efficient way to obtain all novel compounds in high yields (73–93%). Furthermore, a thermochemical analysis, optimization and reactivity indexes such as electronic chemical potential (μ), chemical hardness (η), and electrophilicity (ω) were performed to understand the relationship between the structure and the energetic behavior of all the series. Then, in vitro analysis showed that compounds 27, 29–31, and 34 exhibited inhibitory activity against FXa and the corresponding half maximal inhibitory concentration (IC50) values were calculated. Next, a cell viability assay in HEK293 and HepG2 cell lines, and coagulation parameters (anti FXa, Prothrombin time (PT), activated Partial Thromboplastin Time (aPTT)) of the most active novel molecules were performed to determine the corresponding cytotoxicity and possible action on clotting pathways. The obtained results suggest that compounds 27 and 29 inhibited FXa targeting through coagulation factors in the intrinsic and extrinsic pathways. However, compound 34 may target coagulation FXa mainly by the extrinsic and common pathway. Interestingly, the most active compounds in relation to the inhibition activity against FXa and coagulation parameters did not show toxicity at the performed coagulation assay concentrations. Finally, docking studies confirmed the preferential binding mode of N-propargyltetrahydroquinoline and 1,2,3-triazole derivatives inside the active site of FXa.Fil: Santana Romo, Fabián. Pontificia Universidad Católica de Chile; ChileFil: Lagos, Carlos F.. Universidad San Sebastián; ChileFil: Duarte, Yorley. Universidad Andrés Bello; ChileFil: Castillo, Francisco. Pontificia Universidad Católica de Chile; ChileFil: Moglie, Yanina Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Maestro, Miguel A.. University of A Coruña; EspañaFil: Charbe, Nitin. Pontificia Universidad Católica de Chile; ChileFil: Zacconi, Flavia Cristina Milagro. Pontificia Universidad Católica de Chile; Chil