The use of computational fluid dynamics to study furnace effects in ITS-90 fixed points realizations

Together with the impurities, the thermal fluxes are one of the major sources of uncertainty during the realization of the International Temperature Scale of 1990 (ITS-90) defining fixed points. The use of computational fluid dynamics (CFD) is a valuable tool to develop models that describe the time evolution of the phase transformation (essentially the evolution of the solid–liquid interface) as a function of given theoretical assumptions and given parameters (furnace thermal gradients, freezing initiation, ambient temperature and insulation). The models can be validated by observing the impact of the selected parameters on the observed corresponding melting curves and used to achieve a full understanding of these thermal effects and their impact on uncertainty. This paper proposes an ITS-90 metallic fixed points CFD model together with some results about the influence of the furnace thermal gradients and the freezing initiation techniques.This research is included in the EMRP Joint Research Project SIB10 NOTED, jointly funded by the EMRP participating countries within EURAMET and the European Unio

A novel technique based in a cylindrical microwave resonator for high pressure phase equilibrium determination

Producción CientíficaThe development of a novel technique based on a cylindrical microwave resonator for high pressure phase equilibrium determination is described. Electric permittivity or dielectric constant is a physical property that depends on temperature and pressure ε(p,T). Based on this property, a measuring technique consisting of a cylindrical resonant cavity that works in the microwave spectrum has been developed. Equilibrium data of fluid mixtures are measured at high pressure using a synthetic method, where phase transition is determined under isothermal conditions due to the change of the dielectric constant. This technique may be a more accurate alternative to conventional visual synthetic methods. The technique was validated measuring pure CO2, and phase behaviour was then determined for two binary mixtures [CO2 (0.6) + CH4 (0.4)] and [CO2 (0.4) + CH4 (0.6)], results for which are presented. These systems are interesting for the study of biogas–like mixtures. In addition, data were compared with the equation of state used for natural gas GERG-2008, and also, they were modelled using Peng-Robinson equation of state and Wong- Sandler mixing rules, which are widely employed in chemical industries and which give good results.Trabajo financiado por el Ministerio de Industria, Economía y Competitividad (ENENE2013-47812-R y ENE2017-88474-R) y la Junta de Castilla y León (VA035U16 y VA280P18

Infrared temperature measurement sensors of overhead power conductors

Efficiency in power lines operation is becoming more crucial as the electrification increases and more renewable energies are connected into the grid. New methods and sensors are being added to create smart grids to face these challenges and conductor temperature sensors are one of them. Contact temperature sensors have several problems regarding safety and electronic damage due to the electromagnetic fields induced on the conductors. The goal of this paper is to describe an infrared temperature measurement sensor and to compare contact and non-contact temperatura measurements to estimate the temperature of power lines. Measurements were done for almost a year, storing around 150,000 measures of contact and infrared thermometers for many different weather and load conditions. The results conclude that the infrared system can be successfully used to control the temperature of the overhead conductor within a range of less than 4 _C difference with respect to contact temperature methods for the 88% of the samples and less than 6 _C for the 99%.This research was funded by the EU Regional Development Fund (FEDER) and the Spanish Government under the R+D initiative INNPACTO with reference IPT-2011-1447-920000, ENE-2013-42720-R and RETOS-COLABORACION RTC-2015-3795-3

Use of Eye Tracking as an Innovative Instructional Method in Surgical Human Anatomy

Tobii glasses can record corneal infrared light reflection to track pupil position and to map gaze focusing in the video recording. Eye tracking has been proposed for use in training and coaching as a visually guided control interface. The aim of our study was to test the potential use of these glasses in various situations: explanations of anatomical structures on tablet-type electronic devices, explanations of anatomical models and dissected cadavers, and during the prosection thereof. An additional aim of the study was to test the use of the glasses during laparoscopies performed on Thiel-embalmed cadavers (that allows pneu- moinsufflation and exact reproduction of the laparoscopic surgical technique). The device was also tried out in actual surgery (both laparoscopy and open surgery)

Crown Walls in Mass and Reinforced Concrete: The Way to Aesthetics in Maritime Works

Maritime works are characterized by their remarkable size, length, depth and extraordinarily great demand for natural or artificial materials. To this effect, despite functional designs or the ultimate limit state, a breakwater crown wall can increase the overall effectiveness of the structure in limiting wave overtopping. It will contribute to a reduction of volume of material required and hence the cost to achieve a given level of performance depending on the precautions to be taken on the basis of the critical discharges for functional safety (vehicles, pedestrian and buildings) and structural safety (embankment and revetment seawalls), amongst others. In many cases, bulky mass-concrete elements are designed without any steel reinforcement. Sometimes this effect causes cracking problems in large volumes. The step to slender reinforced concrete elements may take a leap to the aesthetic factor and visual landscape integration in maritime works. In addition, the use of other materials, shapes and colours can bring breakwaters and crown walls to life by creating new functions for maritime works such as a promenade, relaxation or visual enjoyment areas. The aim of this article is to reflect on the issue of bulky mass concrete elements or rebars in slender reinforced concrete crown walls and how the use of these slender elements can bring with it excellent artistic developments as well as the use of other materials in mass concrete sloping, vertical and composite breakwaters and their crown walls. Some breakwaters are no longer just mere defence works but are becoming pieces of art

Updated determination of the molar gas constant R by acoustic measurements in argon at UVa-CEM.

Producción CientíficaA new determination of the molar gas constant was performed from measurements of the speed of sound in argon at the triple point of water and extrapolation to zero pressure. A new resonant cavity was used. This is a triaxial ellipsoid whose walls are gold-coated steel and which is divided into two identical halves that are bolted and sealed with an O-ring. Microwave and electroacoustic traducers are located in the northern and southern parts of the cavity, respectively, so that measurements of microwave and acoustic frequencies are carried out in the same experiment. Measurements were taken at pressures from 600 kPa to 60 kPa and at 273.16 K. The internal equivalent radius of the cavity was accurately determined by microwave measurements and the first four radial symmetric acoustic modes were simultaneously measured and used to calculate the speed of sound. The improvements made using the new cavity have reduced by half the main contributions to the uncertainty due to the radius determination using microwave measurements which amounts to 4.7 parts in 106 and the acoustic measurements, 4.4 parts in 106, where the main contribution (3.7 parts in 106) is the relative excess half-widths associated with the limit of our acoustic model, compared with our previous measurements. As a result of all the improvements with the new cavity and the measurements performed, we determined the molar gas constant R = (8.314449 0.000056) J·K-1·mol-1 which corresponds to a relative standard uncertainty of 6.7 parts in 106. The value reported in this paper lies -1.3 parts in 106 below the recommended value of CODATA 2014, although still within the range consistent with it.2018-08-10MEC ENE2013-47812-RJunta de Castilla y León VA035U1

Diminished neurogenic femoral artery vasoconstrictor response in a Zucker obese rat model: differential regulation of NOS and COX derivatives

Objective: Peripheral arterial disease is one of the macrovascular complications of type 2 diabetes mellitus. This study addresses femoral artery regulation in a prediabetic model of obese Zucker rats (OZR) by examining cross-talk between endothelial and neural factors. Methods and Results: Arterial preparations from lean (LZR) and OZR were subjected to electrical field stimulation (EFS) on basal tone. Nitric oxide synthase (NOS) and cyclooxygenase (COX) isoform expression patterns were determined by immunohistochemical labelling and Western blotting. Results indicate significantly reduced noradrenergic contractions in preparations from OZR compared with those of LZR. Functional inhibition of endothelial NOS (eNOS) indicated a predominant role of this isoform in LZR and its modified activity in OZR. Neural (nNOS) and inducible NOS (iNOS) were activated and their expression was higher in femoral arteries from OZR. Neurotransmission modulated by largeconductance Ca2+-activated (BKCa) or voltage-dependent (KV) K+ channels did not seem compromised in the obese animals. Endothelial COX-1 and COX-2 were expressed in LZR and an additional adventitial location of COX-2 was also observed in OZR, explaining the higher COX-2 protein levels detected in this group. Prostanoids derived from both isoforms helped maintain vasoconstriction in LZR while in OZR only COX-2 was active. Superoxide anion inhibition reduced contractions in endothelium-intact arteries from OZR. Conclusions: Endothelial dysfunction led to reduced neurogenic vasoconstriction in femoral arteries from OZR. In a setting of obesity, NO-dependent nNOS and iNOS dilation activity could be an alternative mechanism to offset COX-2- and reactive oxygen species-mediated vasoconstriction, along with impaired endothelial NO relaxation

Effects of asymmetric dimethylarginine on renal arteries in portal hypertension and cirrhosis

AIM. To evaluate the effects of asymmetric dimethylarginine (ADMA) in renal arteries from portal hypertensive and cirrhotic rats. METHODS. Rat renal arteries from Sham (n = 15), pre-hepatic portal hypertension (PPVL; n = 15) and bile duct ligation and excision-induced cirrhosis (BDL; n = 15) were precontracted with norepinephrine, and additional contractions were induced with ADMA (10-6-10-3 mol/L), an endogenous inhibitor of nitric oxide (NO) synthase. Concentration-response curves to acetylcholine (1 × 10-9-3 × 10-6 mol/L) were determined in precontracted renal artery segments with norepinephrine in the absence and in the presence of ADMA. Kidneys were collected to determine the protein expression and activity of dimethylarginine dimethylaminohydrolase (DDAH), an enzyme that catabolizes ADMA. RESULTS. In renal arteries precontracted with norepinephrine, ADMA caused endothelium-dependent contractions. The pD2 values to ADMA were similar in the Sham and PPVL groups (4.20 ± 0.08 and 4.11 ± 0.09, P > 0.05, respectively), but were lower than those of the BDL group (4.79 ± 0.16, P < 0.05). Acetylcholine-induced endothelium-dependent relaxation that did not differ, in terms of pD2 and maximal relaxation, among the 3 groups studied. Treatment with ADMA (3 × 10-4 mol/L) inhibited acetylcholine-induced relaxation in the 3 groups, but the inhibition was higher (P < 0.05) in the BDL group compared with that for the Sham and PPVL groups. The mRNA and protein expression of DDAH-1 were similar in kidneys from the three groups. Conversely, DDAH-2 expression was increased (P < 0.05) in PPVL and further enhanced (P < 0.05) in the BDL group. However, renal DDAH activity was significantly decreased in the BDL group. CONCLUSION. Cirrhosis increased the inhibitory effect of ADMA on basal- and induced-release of NO in renal arteries, and decreased DDAH activity in the kidney

Basic Study and Clinical Implications of Left Ventricular False Tendon. Is it Associated With Innocent Murmur in Children or Heart Disease?

Introducción y objetivos: El falso tendón del ventrículo izquierdo es una estructura descrita anatómicamente por Turner. Se desconoce su función dentro de la fisiología cardiaca. Se ha postulado, sin alcanzar consenso, su relación con diversas alteraciones eléctricas funcionales. El objetivo es conocer cuando aparece, su prevalencia, su composición histológica y su asociación con el soplo inocente infantil o con enfermedad cardiaca. Métodos: La investigación básica se realizó por la disección anatómica en cadáveres de corazones humanos adultos para describir el falso tendón y su histología. La investigación clínica se realizó en población pediátrica mediante ecocardiografía y se analizó su relación con cardiopatía, el soplo inocente infantil u otras alteraciones. Prenatalmente se realizaron ecocardiografías fetales a diferentes edades gestacionales. Resultados: La presencia del falso tendón es la norma en la disección cardiaca, y está constituido por fibras de tejido muscular y conectivo. En la población pediátrica, la presencia ecocardiografía del falso tendón fue del 83%, y solo mostró relación estadísticamente significativa con el soplo inocente infantil y una menor aceleración de la aorta. Por ecocardiografía fetal, se objetivó su presencia desde al menos la semana 20 de gestación . Conclusiones: El falso tendón del ventrículo izquierdo es una normalidad clínica visible por ecocardiografía fetal ya desde la semana 20, con presencia hasta la edad adulta sin relación con enfermedad, únicamente con la presencia de soplo inocente en edad pediátrica; queda por determinar si es la causa del soplo y si es su ausencia o anomalías estructurales lo que se relaciona con enfermedad.Introduction and objectives: Left ventricular false tendon is a structure of unknown function in cardiac physiology that was first described anatomically by Turner. This condition may be related to various electrical or functional abnormalities, but no consensus has ever been reached. The purpose of this study was to determine the time of appearance, prevalence and histologic composition of false tendon, as well as its association with innocent murmur in children and with heart disease. Methods: The basic research was performed by anatomic dissection of hearts from adult human cadavers to describe false tendon and its histology. The clinical research consisted of echocardiographic study in a pediatric population to identify any relationship with heart disease, innocent murmur in children, or other abnormalities. Fetal echocardiography was performed prenatally at different gestational ages. Results: False tendon was a normal finding in cardiac dissection and was composed of muscle and connective tissue fibers. In the pediatric population, false tendon was present in 83% on echocardiography and showed a statistically significant association only with innocent murmur in children and slower aortic acceleration. The presence of false tendon was first observed on fetal echocardiography from week 20 of pregnancy

Realizing the redefined kelvin: Extending the life of the ITS-90

Following the redefinition of the kelvin [1,2], the user is presented with a more nuanced traceability choice through the mise en pratique for the definition of the kelvin (MeP-K-19) [3]. Here we describe research to address several present and potential shortcomings with the current main dissemination route, namely using the International Temperature Scale of 1990 (ITS-90) [4]. The ITS-90 has served the global temperature measurement community well, providing reliable, low uncertainty traceability for over 30 years. However, there are some potentially life-limiting issues for the ITS-90. Among these are the impact of the main types (1 and 3) of non-uniqueness which currently limit the uncertainties achievable with the ITS-90, and the need to identify a possible alternative to the mercury triple point (a key fixed point of the ITS-90) whose use could be banned by an international treaty [5]. Progress in addressing these problems will be described through: • New determinations of Type 3 non-uniqueness have been undertaken in the range -189 °C to 156 °C; • A comprehensive evaluation of Type 1 non-uniqueness on a large number of Standard Platinum Resistance Thermometers (SPRTs) across multiple regions; • Comparison of high temperature SPRTs in pressure-controlled heat pipes to characterize Type 3 non-uniqueness between 660.323 °C and 961.78 °C; • New designs of CO2 and SF6 cells for use with long-stem SPRTs. These have been improved by using purer gases and more stable and uniform temperature-controlled baths, and by the development of a flexible set-up that can accommodate both capsule and long-stem SPRTs. The effect of replacing mercury on the ITS-90 interpolating equations and uncertainty propagation is also being investigated. References [1] https://www.bipm.org/en/publications/si-brochure [2] G. Machin, The kelvin redefined, Meas. Sci. Technol. 29 022001 (11pp) (2018) https://doi.org/10.1088/1361-6501/aa9ddb [3] B. Fellmuth, J. Fischer, G. Machin, S. Picard, P.P.M. Steur, O. Tamura, D.R. White, H. Yoon, The kelvin redefinition and its mise en pratique, Phil. Trans R. Soc. A., 374 (2064) (2016), p. 20150037, https://doi.org/10.1098/rsta.2015.0037 [4] Real-K project website: https://real-k.aalto.fi/ [5] The use of mercury, even for scientific purposes, could be severely restricted or even banned by international convention (UN Minamata Convention on Mercury which introduces controls over a myriad of products containing mercury)