Where the linearized Poisson-Boltzmann cell model fails: (I) spurious phase separation in charged colloidal suspensions

We perform a linearization of the Poisson-Boltzmann (PB) density functional for spherical Wigner-Seitz cells that yields Debye-H\"uckel-like equations agreeing asymptotically with the PB results in the weak-coupling (high-temperature) limit. Both the canonical (fixed number of microions) as well as the semi-grand-canonical (in contact with an infinite salt reservoir) cases are considered and discussed in a unified linearized framework. In the canonical case, for sufficiently large colloidal charges the linearized theory predicts the occurrence of a thermodynamical instability with an associated phase separation of the homogeneous suspension into dilute (gas) and dense (liquid) phases. In the semi-grand-canonical case it is predicted that the isothermal compressibility and the osmotic-pressure difference between the colloidal suspension and the salt reservoir become negative in the low-temperature, high-surface charge or infinite-dilution (of polyions) limits. As already pointed out in the literature for the latter case, these features are in disagreement with the exact nonlinear PB solution inside a Wigner-Seitz cell and are thus artifacts of the linearization. By using explicitly gauge-invariant forms of the electrostatic potential we show that these artifacts, although thermodynamically consistent with quadratic expansions of the nonlinear functional and osmotic pressure, may be traced back to the non-fulfillment of the underlying assumptions of the linearization.Comment: 32 pages, 3 PostScript figures, submitted to J. Chem. Phy

Comparison of different procedures to map reference evapotranspiration using geographical information systems and regression-based techniques

16 páginas, 6 figuras, 8 tablas.This paper compares different procedures for mapping reference evapotranspiration (ETo) by means of regression-based techniques and geographical information systems (GIS). ETo is calculated following the method of Hargreaves (HG) from a dense database of meteorological stations in the northernmost semi-arid region of Europe, the Ebro valley. The HG method requires the calculation of estimates of extraterrestrial radiation (Ra). We calculated this parameter using two approaches: (1) the common approach that assumes a planar surface and determines the parameter as a function of latitude and (2) using a digital terrain model (DTM) and GIS modelling. The maps were made on a monthly basis using both approaches. We also compared possible propagations of errors in the map calculations for maps derived from modelled layers of maximum and minimum temperatures with those modelled using previously determined local ETo calculations. We demonstrate that calculations of Ra from a DTM and GIS modelling provide a more realistic spatial distribution of ETo than those derived by only considering latitude. It is also preferable to model in advance the variables involved in the calculation of ETo (temperature and Ra) and to subsequently calculate ETo by means of layer algebra in the GIS rather than directly model the local ETo calculations. The obtained maps are useful for the purposes of agriculture and ecological and water resources management in the study area.This work has been supported by the project CGL2005- 04508/BOS financed by the Spanish Comission of Science and Technology (CICYT) and FEDER, PIP176/2005 financed by the Aragón Government, and ‘Programa de grupos de investigación consolidados’ (BOA 48 of 20-04-2005), also financed by the Aragón Government. Research of the third author was supported by postdoctoral fellowship by the Ministerio de Educación, Cultura y Deporte (Spain).Peer reviewe

Many-body interactions and melting of colloidal crystals

We study the melting behavior of charged colloidal crystals, using a simulation technique that combines a continuous mean-field Poisson-Boltzmann description for the microscopic electrolyte ions with a Brownian-dynamics simulation for the mesoscopic colloids. This technique ensures that many-body interactions between the colloids are fully taken into account, and thus allows us to investigate how many-body interactions affect the solid-liquid phase behavior of charged colloids. Using the Lindemann criterion, we determine the melting line in a phase-diagram spanned by the colloidal charge and the salt concentration. We compare our results to predictions based on the established description of colloidal suspensions in terms of pairwise additive Yukawa potentials, and find good agreement at high-salt, but not at low-salt concentration. Analyzing the effective pair-interaction between two colloids in a crystalline environment, we demonstrate that the difference in the melting behavior observed at low salt is due to many-body interactions

Энергоэффективный асинхронный двигатель

Выпускная квалификационная работа 109 с., 10 рис., 31 табл., 10 источников. Ключевые слова: энергоэффективный двигатель, КПД, короткозамкнутый ротор, число витков, воздушный зазор, асинхронный двигатель, класс энергоэффективности. Объектом исследования - асинхронный двигатель с короткозамкнутым ротором. Цель работы – анализ способов повышения энергоэффективности при проектировании асинхронных двигателей, освоение методики проектирования энергоэффективных машин. В процессе исследования проведен электромагнитный расчет включающий: расчет параметров статора и ротора, магнитной цепи, расчет потерь, построение рабочих и пусковых характеристик, тепловой и механический расчеты. В результате исследования был спроектирован энергоэффективный асинхронный двигатель при изменении числа витков обмотки статора и длины воздушного зазора. Исходные данные к работе: высота оси вращения 132 мм, количество полюсов - 4, номинальная мощность 7.5 кВт. Область применения: общепромышленный. Экономическая эффективность/значимость работы: снижение энергопотребления по сравнению с обычными двигателями, повышение надежности двигателя.The final qualifying work contains 109 pages, 10 pictures, 31 tables, 10 sources. Keywords: energy-efficient motor, efficiency, squirrel-cage rotor, number of turns, air-gap, induction motor, class of energy efficiency. The object of the research – an induction motor with the squirrel-cage rotor. The aim of the research - analysis of ways to improve energy efficiency in the design of induction motors, development of design methods. The electromagnetic calculation has been made during the process of the study. It includes calculations of parameters of stator and rotor, magnetic circuit, all motor`s losses, plotting of operating and starting curves. In the result of the research, energy-efficient motor has been designed with different number of turns and length of air-gap. Input data: shaft height is 132 millimeters, number of poles – 4, rated power – 7.5 kWt. Economic efficiency/ importance: less energy consumption compared with common induction motors, increasing of reliability of the motor

Influencia de dietas con diferentes ácidos grasos insaturados sobre inflamación y estrés oxidativo hepático. Efecto de los ácidos grasos trans

Los ácidos docosahexaenoico (DHA, 22:6 n-3) y araquidónico (AA, 20:4 n-6) determinan los niveles de mediadores lipídicos anti y proi-inflamatorios que son derivados de éstos ácidos grasos (AG) poliinsaturados (AGPI), por acción de enzimas, como las ciclooxigenasas (COX1 y COX2). El tipo de grasa dietaria, y algunos isómeros como los ácidos grasos trans (AGt), podrían modular parámetros relacionados a la inflamación y al estrés oxidativo

Impact of circulating bacterial DNA in long-term glucose homeostasis in non-diabetic patients with HIV infection: cohort study

In HIV-infected patients, the damage in the gut mucosal immune system is not completely restored after antiretroviral therapy (ART). It results in microbial translocation, which could influence the immune and inflammatory response. We aimed at investigating the long-term impact of bacterial-DNA translocation (bactDNA) on glucose homeostasis in an HIV population. This was a cohort study in HIV-infected patients whereby inclusion criteria were: patients with age >18 years, ART-naïve or on effective ART (<50 HIV-1 RNA copies/mL) and without diabetes or chronic hepatitis C. Primary outcome was the change in HbA1c (%). Explanatory variables at baseline were: bactDNA (qualitatively detected in blood samples by PCR [broad-range PCR] and gene 16SrRNA - prokaryote), ART exposure, HOMA-R and a dynamic test HOMACIGMA [continuous infusion of glucose with model assessment], hepatic steatosis (hepatic triglyceride content - 1H-MRS), visceral fat / subcutaneous ratio and inflammatory markers. Fifty-four men (age 43.2 ± 8.3 years, BMI 24.9 ± 3 kg/m2, mean duration of HIV infection of 8.1 ± 5.3 years) were included. Baseline HbA1c was 4.4 ± 0.4% and baseline presence of BactDNA in six patients. After 8.5 ± 0.5 years of follow-up, change in HbA1c was 1.5 ± 0.47% in patients with BactDNA vs 0.87 ± 0.3% in the rest of the sample p < 0.001. The change in Hba1c was also influenced by protease inhibitors exposure, but not by baseline indices of insulin resistance, body composition, hepatic steatosis, inflammatory markers or anthropometric changes. In non-diabetic patients with HIV infection, baseline bacterial translocation and PI exposure time were the only factors associated with long-term impaired glucose homeostasis

Post-surgical complications in patients undergoing radical cystectomy according to the patient’s nutritional status

Introducción: La cistectomía radical es el tratamiento de elección para los tumores vesicales musculo-invasivos presentando una gran morbilidad y una considerable tasa de mortalidad. Un factor importante a tener en cuenta es el estado nutricional del paciente ya que puede impactar de forma negativa en la evolución clínica de los pacientes. Material y métodos: Realizamos un estudio retrospectivo de las cistectomías realizadas entre 2012 y 2015 en el servicio de Urología de HU Son Espases y se evalúa la aparición de complicaciones postoperatorias según el estado nutricional calórico calculado a través del IMC, el estado nutricional proteico calculado a través de la albúmina postoperatoria inmediata y el estado nutricional inmunológico a través de los linfocitos totales. Resultados: Presentaron alguna complicación el 42% de los pacientes. Un 21% presentaron únicamente una complicación Clavien II y un 21% presentaron una complicación mayor a Clavien III o más de una complicación. Se encontraron diferencias estadísticamente significativas según el estado nutricional proteico (Normal-leve vs moderado-grave) en la fuga de la anastomosis uretero-ileal. No se encontraron diferencias en el resto de variables. Conclusiones: La mayoría de pacientes sometidos a cistectomía radical con derivación urinaria tipo intestinal presentan algún estado de malnutrición proteica postoperatoria. En nuestra serie, el estado nutricional proteico del paciente presenta una relación con la aparición de fuga de la anastomosis uretero-ileal.Radical cystectomy is the election treatment for muscle-invasive bladder tumors presenting a high morbidity and significant mortality rate. An important factor to consider is the nutritional status of the patient because it can negatively impact the clinical course of patients. Methods: We perfomed a retrospective study of radical cystectomies with intestinal conduct between 2012 and 2015 in the department of Urology in HU Espases and we evaluated the postoperative complications according to the caloric nutritional status calculated by BMI, protein nutritional status calculated by the immediate postoperative albumin and the inmunological nutritional status by total account of lymphocites. Results: Developed complications the 42% of patients. 21% had only one complication Clavien II and 21% had one complication Clavien III or more than one complication. We found statistically significant differences with the protein nutritional status (mild Normal-vs moderate to severe) in the escape of the ureter-ileal anastomosis. No differences in the other variables were found. Conclusions: Most patients undergoing radical cystectomy with intestinal conduct type have a postoperative state of protein malnutrition. In our series, the protein nutritional status of the patient has a relationship with the occurrence of leakage from the ureter-ileal anastomosis