Redox Potentials as Reactivity Descriptors in Electrochemistry

A redox catalyst can be present in the solution phase or immobilized on the electrode surface. When the catalyst is present in the solution phase the process can proceed via inner- (with bond formation, chemical catalysis) or outer-sphere mechanisms (without bond formation, redox catalysis). For the latter, log k is linearly proportional to the redox potential of the catalysts, E°. In contrast, for inner-sphere catalyst, the values of k are much higher than those predicted by the redox potential of the catalyst. The behaviour of these catalysts when they are confined on the electrode surface is completely different. They all seem to work as inner-sphere catalysts where a crucial step is the formation of a bond between the active site and the target molecule. Plots of (log i)E versus E° give linear or volcano correlations. What is interesting in these volcano correlations is that the falling region corresponding to strong adsorption of intermediates to the active sites is not necessarily attributed to a gradual surface occupation of active sites by intermediates (Langmuir isotherm) but rather to a gradual decrease in the amount of M(II) active sites which are transformed into M(III)OH inactive sites due to the applied potential

Major histocompatibility complex associations of ankylosing spondylitis are complex and involve further epistasis with ERAP1

Ankylosing spondylitis (AS) is a common, highly heritable, inflammatory arthritis for which HLA-B*27 is the major genetic risk factor, although its role in the aetiology of AS remains elusive. To better understand the genetic basis of the MHC susceptibility loci, we genotyped 7,264 MHC SNPs in 22,647 AS cases and controls of European descent. We impute SNPs, classical HLA alleles and amino-acid residues within HLA proteins, and tested these for association to AS status. Here we show that in addition to effects due to HLA-B*27 alleles, several other HLA-B alleles also affect susceptibility. After controlling for the associated haplotypes in HLA-B, we observe independent associations with variants in the HLA-A, HLA-DPB1 and HLA-DRB1 loci. We also demonstrate that the ERAP1 SNP rs30187 association is not restricted only to carriers of HLA-B*27 but also found in HLA-B*40:01 carriers independently of HLA-B*27 genotype

NURBS distance fields for extremely curved cracks

This paper presents the first methodology that combines a meshless method and the exact representation of cracks using Non-Uniform Rational B-Splines (NURBS). The methodology consists on developing an enrichment function based on distance functions to NURBS curves.The examples show the potential of the proposed approach and demonstrate the applicability to problems involving complex cracks that appear in sol-gel films

Propuesta de balanced scorecard para Gea Westfalia Separator Chile S. A

Tesis (Ingeniero Civil Industrial)Existe la necesidad de que las organizaciones cuenten con sistema de control de gestión, que permita hacer mediciones, puesto que “si no puedes medirlo, no puedes gestionarlo" (Kaplan y Norton, 2002, p.34). Un sistema de medición de una organización, en conjunto con su gestión, permite que ésta sobreviva a la competencia del entorno. El control de gestión específicamente el Balanced Scorecard, proporcionan una herramienta útil, para dirigir y controlar empresas en forma pro-activa en el corto y largo plazo. La idea de proponer una herramienta de control es mejorar la gestión, ya sea financiera y no financiera de la empresa, con el fin de hacer más eficiente y eficaz la manera de realizar el quehacer más permanente de ella. El problema a estudiar en la presente investigación, es la carencia de una planificación estratégica, y la no evaluación de los resultados, lo cual no permite tener una evaluación objetiva del desempeño de la gestión de Gea Westfalia Separator Chile S.A. Gea Westfalia Separator Chile S.A., carece de un sistema de planificación, sin mencionar que no cuenta con una misión y visión a nivel de empresa, por lo que cada departamento trabaja de manera individual, sin una interacción de sus procesos internos. Por lo anterior en esta organización no existen herramientas formales de gestión, que establezcan los objetivos de forma clara, medición y cumplimento de estos de manera integral. Es importante entonces desarrollar un mecanismo de gestión, que permita monitorear y controlar el desempeño global de la organización, ayudando a no estancarse en el quehacer diario, lo cual le impide realizar la planificación a mediano y largo plazo

Simulación para Estimación de Muertes por Cáncer de Pulmón por Contaminación Ambiental de PM2.5.

The objective of this study is to simulate the estimation of the number of deaths from lung cancer caused by environmental pollution due to human exposure to fine particulate matter less than 2.5 µm (PM2.5). To achieve this goal, the study was conducted with deductive approach.  A simulation environmental model to assess morbidity developed by the World Health Organization was applied, based on population exposure to PM2.5 pollutant. This was done with data obtained from 12 air quality stations of the Metropolitan District of Quito and the population groups exposed to PM2.5, determining the impact on health.  The final simulation was calculated using the death rate in the population. For the period 1990-2020, the total number of deaths due to lung neoplasms was 3058 ± 24.  The number of these deaths associated to PM2.5 pollution was 523 ± 32, which supposes a Relative Risk of 523 ± 32, equivalent to  17.1%, CI=95% [15.9%-18.3%]. These results were obtained through software developed for this purpose. In conclusion, the values obtained in the present simulation are within the confidence interval of other similar studies.El objetivo de este estudio es estimar el número de muertes por cáncer de pulmón  provocadas por la contaminación ambiental debida a la exposición de las personas a material particulado fino menor a 2.5 µm (PM2.5).  Para cumplir con este fin, se realizó un estudio con enfoque deductivo en el que se efectuaron simulaciones del modelo de evaluación de la morbilidad ambiental desarrollado por la Organización Mundial de la Salud.  Se evaluó la exposición de la población a la contaminación por PM2.5, basado en datos monitoreados en 12 estaciones de calidad de aire del Distrito Metropolitano de Quito en los grupos de población expuestas a PM2.5, y la incidencia  en la salud, estimada en la tasa de mortalidad en la población. Para el período de análisis 1990-2020 el total de muertes por neoplasias pulmonares es de 3058 ± 24 de los cuales 523 ± 32 se asociarían con las concentraciones de PM2.5; equivalente al 17.1%, CI=95% [15.9%-18.3%] y un Riesgo Relativo de 1.2046 [1.0688, 1.394]. Estos resultados fueron obtenidos a través de un software desarrollado para el efecto.   En conclusión, los valores obtenidos en la presente simulación se encuentran dentro del intervalo de confianza en relación a otros estudios similares

Estado nutricional y fuerza de tren inferior: diferencias entre sexo y área geográfica entre niños y niñas

The present cross-sectional study aims to determine an establish the association between the variables of nutritional status and lower segment in Chilean students from Araucanía Region an urban sector in contrast to students from a rural sector. The sample was 120 schoolchildren, divided into 60 boys and 60 girls whose ages fluctuated between 10 and 11 years of age. BMI (Kg / H ^ 2) was measured to later classify their nutritional status and also the Sargent vertical jump test (lower body strength) in the school population. The groups were compared with the statistical T-student test for independent samples with 95% confidence intervals. Pearson's correlation was performed for the results of the Sargent test. A high prevalence of girls from both sectors was found, classified as overweight and in the obesity range. Likewise, there are more overweight children in the urban sector than in the rural sector. Presenting similarity in the vertical jump test (Sargent test) where there were no significant differences when correlating between sex and geographic area.Este estudo transversal visa determinar e estabelecer a associação entre as variáveis ​​do estado nutricional e força no segmento inferior entre os alunos chilenos correspondentes à região de Araucanía, pertencentes a um setor urbano em contraste com os alunos do setor rural. A amostra foi composta por 120 escolares, divididos em 60 meninos e 60 meninas com idades variando de 10 a 11 anos. Foi realizada a mensuração do IMC (Kg / H ^ 2) para posteriormente classificar o estado nutricional e também o teste de salto vertical Sargent's Test (força de membros inferiores) na população escolar. Os grupos foram comparados com o teste estatístico Qui-quadrado com intervalos de confiança de 95%. Para os resultados do teste de Sargent, foi realizada a correlação de Pearson. Foi encontrada alta prevalência de meninas de ambos os setores, classificadas nas faixas de sobrepeso e obesidade. Da mesma forma, apresentam semelhança no teste de salto vertical (teste de Sargent) onde não houve diferenças significativas na correlação entre sexo e área geográfica.El presente estudio transversal pretende determinar y establecer la asociación entre las variables de estado nutricional y fuerza en el segmento inferior entre estudiantes Chilenos correspondientes a la región de la Araucanía, pertenecientes a un sector urbano en contraste con estudiantes de un sector rural. La muestra fue de 120 escolares, divididos en 60 niños y 60 niñas cuyas edades fluctuaron entre los 10 y 11 años . Se realizó medición del IMC (Kg/H^2) para luego clasificar su estado nutricional y también la prueba de salto vertical Test de Sargent (fuerza de tren inferior) en la población escolar. Los grupos fueron comparados con la prueba estadística Chi-cuadrado con intervalos de confianza del 95 %. Para los resultados del test de Sargent se realizó correlación de Pearson. Se encontró una alta prevalencia de niñas de ambos sectores, encasilladas en el rango de sobrepeso y obesidad. Así mismo, presentan similitud en la prueba de salto vertical (test de Sargent) en donde no existieron diferencias significativas al momento de correlacionar entre sexo y área geográfica

Relaxation time asymmetry in stator dynamics of the bacterial flagellar motor

The bacterial flagellar motor (BFM) is the membrane-embedded rotary molecular motor which turns the flagellum that provides thrust to many bacterial species. This large multimeric complex, composed of a few dozen constituent proteins, has emerged as a hallmark of dynamic subunit exchange. The stator units are inner-membrane ion channels which dynamically bind and unbind to the peptidoglycan at the rotor periphery, consuming the ion motive force (IMF) and applying torque to the rotor when bound. The dynamic exchange is known to be a function of the viscous load on the flagellum, allowing the bacterium to dynamically adapt to its local viscous environment, but the molecular mechanisms of exchange and mechanosensitivity remain to be revealed. Here, by actively perturbing the steady-state stator stoichiometry of individual motors, we reveal a stoichiometry-dependent asymmetry in stator remodeling kinetics. We interrogate the potential effect of next-neighbor interactions and local stator unit depletion and find that neither can explain the observed asymmetry. We then simulate and fit two mechanistically diverse models which recapitulate the asymmetry, finding stator assembly dynamics to be particularly well described by a two-state catch-bond mechanism

Enhancement of the catalytic activity of fe phthalocyanine for the reduction of O 2 anchored to Au(111) via conjugated self-assembled monolayers of aromatic thiols as compared to Cu phthalocyanine

We have prepared self-assembled monolayers (SAMs) of 4-aminothiophenol (4-ATP) and 1-(4-mercaptophenyl)-2,6-diphenyl-4-(4-pyridyl)pyridinium tetrafluoroborate (MDPP) functionalized with iron phthalocyanine (FePc) and copper phthalocyanine (CuPc) adsorbed on gold (111) electrodes. The catalytic activity of these SAMs/MPc was examined for the reduction of O 2 in aqueous solutions and compared to that of bare gold and with gold coated directly with preadsorbed MPc molecules. Scanning tunneling microscopy (STM) studies confirm the functionalization of the 4-ATP by MPc. STM images reveal that iron phthalocyanine molecules are chemically anchored to 4-aminothiophenol organic monolayers, probably having an "umbrella" type orientation with regards to the surface. The electrocatalytic studies carried out with Au/4-ATP/FePc and Au/MDPP/FePc electrodes show that the O 2 reduction takes place by the transfer of 4-electron to give water in contrast to a 2-electron transfer process observed for th