Study of waterborne polyurethane materials under aging treatments. Effect of the soft segment length

Coatings made of waterborne polyurethane dispersions are a promising alternative to solvent-borne ones but their mechanical and thermal properties under harsh outdoor conditions such as high temperature and humidity are somewhat limited. In this work saturated polyesters (PBA) with different molecular weights (800–2600 g/mol) were synthesized by reacting adipic acid with 1,4 butanediol. These polyols, an internal emulsifier, and an aliphatic diisocyanate were used as raw materials to synthesize polyurethane (PU) aqueous dispersions with solids contents of 29–38 wt%. The increase of the molecular weight of the polyol decreased the mean particle size of the PU dispersions from 308 to 78 nm. Polyurethane (PU) films were obtained by water evaporation of the PU dispersions and they were annealed at 80 °C for 2 h. Accelerated aging studies were performed by submerging the PU films in the water at 80 °C for 2 h. The PU films synthesized with the polyols with lower molecular weight exhibited enhanced phase miscibility, giving place to storage and loss moduli of similar magnitudes in a wide temperature range and they were less susceptible to hydrolytic degradation. Microphase miscibility was favored when shorter polyols are used. Contact angle measurement and cross-hatch adhesion test on PU coatings placed on stainless steel plate, before and after annealing and water aging were carried out. All PU coatings retained the adhesion to the substrate after aging, the PU coatings synthesized with shorter polyols exhibited enhanced adhesion.The authors thank the University of Antioquia for the “Estudiante Instructor” grant and to CODI for the economic and time support on the project 785 registered in the act 2018-19331

Phenomenology of a three-family model with gauge symmetry SU(3)_c X SU(4)_L X U(1)_X

We study an extension of the gauge group SU(3)_c X SU(2)_L X U(1)_Y of the standard model to the symmetry group SU(3)_c X SU(4)_L X U(1)_X (3-4-1 for short). This extension provides an interesting attempt to answer the question of family replication in the sense that models for the electroweak interaction can be constructed so that anomaly cancellation is achieved by an interplay between generations, all of them under the condition that the number of families must be divisible by the number of colours of SU(3)_c. This method of anomaly cancellation requires a family of quarks transforming differently from the other two, thus leading to tree-level flavour changing neutral currents (FCNC) transmitted by the two extra neutral gauge bosons $Z'$ and $Z''$ predicted by the model. In a version of the 3-4-1 extension, which does not contain particles with exotic electric charges, we study the fermion mass spectrum and some aspects of the phenomenology of the neutral gauge boson sector. In particular, we impose limits on the $Z-Z'$ mixing angle and on the mass scale of the corresponding physical new neutral gauge boson $Z_2$, and establish a lower bound on the mass of the additional new neutral gauge boson $Z'' \equiv Z_3$. For the analysis we use updated precision electroweak data at the Z-pole from the CERN LEP and SLAC Linear Collider, and atomic parity violation data. The mass scale of the additional new neutral gauge boson $Z_3$ is constrained by using updated experimental inputs from neutral meson mixing in the analysis of the sources of FCNC in the model. The data constrain the $Z-Z'$ mixing angle to a very small value of O(0.001), and the lower bounds on $M_{Z_2}$ and on $M_{Z_3}$ are found to be of O(1 TeV) and of O(7 TeV), repectively.Comment: 22 pages, 6 tables, 1 figure. To appear in J. Phys. G: Nuclear and Particle Physic

Frecuencias alélicas, genotípicas y haplotípicas HLA-A, HLA-B, HLA-DRB1 en donantes fallecidos, Medellín, Colombia

Introduction. Genetic characterization of the human leucocyte antigen (HLA) system has provided insights into mechanisms of susceptibility to diverse diseases and immunological phenomena during pregnancy, as well as providing evidence for compatibility in the selection of organ transplant donors and recipients.Objective. The HLA-A,-B,-DRB1 allele, genotype and haplotype frequencies were determined in deceased organ donors in Medellín, Colombia.Materials and methods. The genotypes of 926 deceased donors were evaluated over a 17- year period (1989- 2006). HLA-A, HLA-B and HLA-DRB1 typing was performed by sequence specific primer-polymerase chain reaction (SSP-PCR). Maximum likelihood frequencies were estimated by the zipper version of expectation maximation algorithm. Hardy-Weinberg equilibrium were determined by an exact test analogous to Fisher's test by using Markov's chain, and linkage disequilibrium between pairs of loci.Results. Twenty-two, 43 and 14 alleles were identified for HLA-A, -B and -DRB loci, respectively. The most frequent were A*02, A*24, B*35, and DRB1*04. A deficiency in the proportion of heterozygotes in HLA-A and B loci (p<0.01 and p<0.00001, respectively). The most frequent haplotypes were as follows: HLA-A*24, B*35 (7.7%) for HLA-A,-B; HLA-B*35, DRB1*04 (6.4%) for HLA-B,-DRB1 and HLA-A*24, DRB1*04 (8.9%) for HLA-A,-DRB1. For the 3 loci HLA-A,-B,-DRB1, the most frequent haplotypes were A*24, B*35, DRB1*04 (4.6%) and A*24, B*61, DRB1*04 (2.0%).Conclusions. These results confirm the three-ethnic ancestry of the Medellin population. The predominance of Caucasian admixture differs from many other Latin-American populations and can serve as a reference for comparative studies of these populations as well as applications within the Medellin population.Introducción. La caracterización genética del sistema HLA es de gran utilidad en estudios antropogenéticos, en la comprensión de mecanismos asociados a susceptibilidad o resistencia a diversas enfermedades, en los fenómenos inmunológicos durante el embarazo y en la selección de donantes/receptores en trasplantes de órganos.Objetivo. Determinar las frecuencias alélicas, genotípicas y haplotípicas HLA-A, -B, -DRB1 en donantes fallecidos en Medellín.Materiales y métodos. Se incluyeron 926 donantes entre febrero de 1989 y septiembre de 2006, a los cuales se les realizó la tipificación HLA-A, -B, -DRB1 por PCR-SSP (single specific primer-polymerase chain reaction) de mediana resolución. Las frecuencias alélicas, genotípicas y haplotípicas fueron estimadas mediante el algoritmo de máxima verosimilitud. Se evaluó el ajuste al equilibrio de Hardy-Weimberg por una prueba exacta análoga a la de Fisher usando la cadena de Markov, así como el desequilibrio de ligamiento entre pares de loci.Resultados. Se identificaron 22, 43 y 14 alelos para los loci HLA-A, -B, -DRB, respectivamente, de los cuales los más frecuentes fueron: A*02, A*24, B*35 y DRB1*04. En los loci HLA-A y -B se observó deficiencia en la frecuencia de heterocigóticos esperada (p<0,01 y p<0,00001, respectivamente). Los haplotipos más frecuentes fueron HLA-A*24, B*35 (7,7%), HLA-B*35 DRB1*04 (6,4%) y HLA-A*24, DRB1*04 (8,9%) para HLA-A, -DRB1, y para 3 loci fueron HLAA* 24, B*35, DRB1*04 (4,6%) y HLA-A*24, B*61, DRB1*04 (2,0%).Conclusiones. Estos resultados corroboran la composición triétnica de nuestra población, en la cual predomina el grado de mezcla caucásica, a diferencia de otras latinoamericanas, y podrán ser usados como referencia para otros estudios y aplicaciones en esta población

Effect of chronic exercise on myocardial electrophysiological heterogeneity and stability. Role of intrinsic cholinergic neurons: A study in the isolated rabbit heart

[EN] A study has been made of the effect of chronic exercise on myocardial electrophysiological heterogeneity and stability, as well as of the role of cholinergic neurons in these changes. Determinations in hearts from untrained and trained rabbits on a treadmill were performed. The hearts were isolated and perfused. A pacing electrode and a recording multielectrode were located in the left ventricle. The parameters determined during induced VF, before and after atropine (1 mu M), were: fibrillatory cycle length (VV), ventricular functional refractory period (FRPVF), normalized energy (NE) of the fibrillatory signal and its coefficient of variation (CV), and electrical ventricular activation complexity, as an approach to myocardial heterogeneity and stability. The VV interval was longer in the trained group than in the control group both prior to atropine (78 +/- 10 vs. 68 +/- 10 ms) and after atropine (76 +/- 8 vs. 67 +/- 10 ms). Likewise, FRPVF was longer in the trained group than in the control group both prior to and after atropine (53 +/- 8 vs. 42 +/- 7 ms and 50 +/- 6 vs. 40 +/- 6 ms, respectively), and atropine did not modify FRPVF. The CV of FRPVF was lower in the trained group than in the control group prior to atropine (12.5 +/- 1.5% vs. 15.1 +/- 3.8%) and, decreased after atropine (15.1 +/- 3.8% vs. 12.2 +/- 2.4%) in the control group. The trained group showed higher NE values before (0.40 +/- 0.04 vs. 0.36 +/- 0.05) and after atropine (0.37 +/- 0.04 vs. 0.34 +/- 0.06; p = 0.08). Training decreased the CV of NE both before (23.3 +/- 2% vs. 25.2 +/- 4%; p = 0.08) and after parasympathetic blockade (22.6 +/- 1% vs. 26.1 +/- 5%). Cholinergic blockade did not modify these parameters within the control and trained groups. Activation complexity was lower in the trained than in the control animals before atropine (34 +/- 8 vs. 41 +/- 5), and increased after atropine in the control group (41 +/- 5 vs. 48 +/- 9, respectively). Thus, training decreases the intrinsic heterogeneity of the myocardium, increases electrophysiological stability, and prevents some modifications due to muscarinic block.This research was supported by the Spanish Ministry of Education and Science, (DEP2007-73234-C03-01 to AMA), http://www.mecd.gob.es/portada-mecd/; and the Generalitat Valenciana (PROMETEO 2010/093 to FJC, and FPI/2008/003 to MZ), http://www.gva.es/va/inicio/presentacion; jsessionid=ydprbDQZTsCTz85W1Such-Miquel, L.; Brines-Ferrando, L.; Alberola, A.; Zarzoso Muñoz, M.; Chorro Gasco, FJ.; Guerrero-Martínez, JF.; Parra-Giraldo, G.... (2018). Effect of chronic exercise on myocardial electrophysiological heterogeneity and stability. Role of intrinsic cholinergic neurons: A study in the isolated rabbit heart. 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(2011). The training-induced changes on automatism, conduction and myocardial refractoriness are not mediated by parasympathetic postganglionic neurons activity. European Journal of Applied Physiology, 112(6), 2185-2193. doi:10.1007/s00421-011-2189-4Billman, G. E. (2009). Cardiac autonomic neural remodeling and susceptibility to sudden cardiac death: effect of endurance exercise training. American Journal of Physiology-Heart and Circulatory Physiology, 297(4), H1171-H1193. doi:10.1152/ajpheart.00534.2009HAN, J., & MOE, G. K. (1964). Nonuniform Recovery of Excitability in Ventricular Muscle. Circulation Research, 14(1), 44-60. doi:10.1161/01.res.14.1.44Beaumont, E., Salavatian, S., Southerland, E. M., Vinet, A., Jacquemet, V., Armour, J. A., & Ardell, J. L. (2013). Network interactions within the canine intrinsic cardiac nervous system: implications for reflex control of regional cardiac function. The Journal of Physiology, 591(18), 4515-4533. doi:10.1113/jphysiol.2013.259382Armour, J. 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Features of patients hospitalized to the newborn intensive care at Clínica Universidad de La Sabana

Introducción: Es pertinente conocer las características de los pacientes que ingresan a las unidades de cuidado intensivo neonatal para que las acciones en salud respondan a sus necesidades particulares. Objetivo: Caracterizar los pacientes que ingresaron a la Unidad de Cuidado Intensivo Neonatal (UCIN) de la Clínica de la Universidad de La Sabana de enero a diciembre del 2012. Materiales y Métodos: estudio retrospectivo con n=206 neonatos que ingresaron a la UCIN de la Clínica Universidad de La Sabana en el 2012, se revisaron las historias clínicas de los pacientes ingresados para identificar sus características, se calcularon frecuencias relativas y absolutas; y para las variables cuantitativas se describieron medidas de tendencia central y dispersión. Resultados: el 56,3% eran hombres, el promedio de edad gestacional de 36,5 semanas (SD 3,3 semanas), el peso promedio fue de 2625,9 g (SD 757,5 g). La mediana de los días de estancia fue de 4 (IQR: 2 a 9). El principal diagnóstico fue ictericia neonatal en (21,8%), el 22% de los pacientes requirieron ventilación mecánica (VM). La media de la edad gestacional y del peso en pacientes con requerimientos de VM fue de 32.7 semanas (SD: 3,7 semanas) y 1883 g (SD: 779 g) respectivamente, comparado con 37,6 semanas (SD: 2,2 semanas) y 2840 g (SD: 601 g) en los que no requirieron VM. Conclusiones: características como bajo peso al nacer, edad gestacional temprana y el uso de surfactante, seasociaron con el requerimiento de VM, adicionalmente la mortalidad calculada fue del 2,8%.Introduction: It is relevant to know the characteristics of patients who enter to neonatal intensive care units in order to learn how to respond to their specific conditions and which health actions can be applied for their particular needs. Objective: The aim of this study is describe patients admitted at Clinica Universidad de La Sabana (Neonatal Intensive Care -NIC) from January to December 2012. Materials and Methods: Retrospective study with n=206 neonates admitted to the NIC at Clinica Universidad de La Sabana in 2012, medical records of patients admitted were reviewed to identify its characteristics, as well absolute and relative frequencies were calculated. In terms of quantitative variables, they were measured with central tendency and dispersion. Results: 56.3% of patients were men, the average gestational age was 36.5 weeks (SD 3.3 weeks), the average weight was 2625 gr (SD 757.5 gr). The median days of stay was 4 (IQR:2-9). The main diagnosis was neonatal icterus (21.8%); 22% of patient’s required mechanical ventilation (MV). The mean gestational age and weight in patients with VM requirements was 32.7 weeks (SD: 3.7 weeks) and 1883 gr (SD: 779 gr) respectively. Contrasted with the gestational age and weight of newborns that not requiring VM was 37.6 weeks (SD 2.2 weeks) and 2840 gr (SD: 601 gr). Conclusions: Low birth weight, early gestational age and the use of surfactant, were associated with the requirement of VM, and the mortality found was 2.8% for the whole cohort

Minimal Scalar Sector of 3-3-1 Models without Exotic Electric Charges

We study the minimal set of Higgs scalars, for models based on the local gauge group $SU(3)_c \otimes SU(3)_L \otimes U(1)_X$ which do not contain particles with exotic electric charges. We show that only two Higgs $SU(3)_L$ triplets are needed in order to properly break the symmetry. The exact tree-level scalar mass matrices resulting from symmetry breaking are calculated at the minimum of the most general scalar potential, and the gauge bosons are obtained, together with their couplings to the physical scalar fields. We show how the scalar sector introduced is enough to produce masses for fermions in a particular model which is an $E_6$ subgroup. By using experimental results we constrain the scale of new physics to be above 1.3 TeV.Comment: LaTeX, 22 pages, 1 figure include

IFNγ Response to Mycobacterium tuberculosis, Risk of Infection and Disease in Household Contacts of Tuberculosis Patients in Colombia

OBJECTIVES: Household contacts (HHCs) of pulmonary tuberculosis patients are at high risk of Mycobacterium tuberculosis infection and early disease development. Identification of individuals at risk of tuberculosis disease is a desirable goal for tuberculosis control. Interferon-gamma release assays (IGRAs) using specific M. tuberculosis antigens provide an alternative to tuberculin skin testing (TST) for infection detection. Additionally, the levels of IFNgamma produced in response to these antigens may have prognostic value. We estimated the prevalence of M. tuberculosis infection by IGRA and TST in HHCs and their source population (SP), and assessed whether IFNgamma levels in HHCs correlate with tuberculosis development. METHODS: A cohort of 2060 HHCs was followed for 2-3 years after exposure to a tuberculosis case. Besides TST, IFNgamma responses to mycobacterial antigens: CFP, CFP-10, HspX and Ag85A were assessed in 7-days whole blood cultures and compared to 766 individuals from the SP in Medellín, Colombia. Isoniazid prophylaxis was not offered to child contacts because Colombian tuberculosis regulations consider it only in children under 5 years, TST positive without BCG vaccination. RESULTS: Using TST 65.9% of HHCs and 42.7% subjects from the SP were positive (OR 2.60, p<0.0001). IFNgamma response to CFP-10, a biomarker of M. tuberculosis infection, tested positive in 66.3% HHCs and 24.3% from the SP (OR = 6.07, p<0.0001). Tuberculosis incidence rate was 7.0/1000 person years. Children <5 years accounted for 21.6% of incident cases. No significant difference was found between positive and negative IFNgamma responders to CFP-10 (HR 1.82 95% CI 0.79-4.20 p = 0.16). However, a significant trend for tuberculosis development amongst high HHC IFNgamma producers was observed (trend Log rank p = 0.007). DISCUSSION: CFP-10-induced IFNgamma production is useful to establish tuberculosis infection prevalence amongst HHC and identify those at highest risk of disease. The high tuberculosis incidence amongst children supports administration of chemoprophylaxis to child contacts regardless of BCG vaccination

Cross section measurements of 155,157Gd(n, γ) induced by thermal and epithermal neutrons

Neutron capture cross section measurements on Gd and Gd were performed using the time-of-flight technique at the n_TOF facility at CERN on isotopically enriched samples. The measurements were carried out in the n_TOF experimental area EAR1, at 185 m from the neutron source, with an array of 4 CD liquid scintillation detectors. At a neutron kinetic energy of 0.0253 eV, capture cross sections of 62.2(2.2) and 239.8(8.4) kilobarn have been derived for Gd and Gd, respectively, with up to 6% deviation relative to values presently reported in nuclear data libraries, but consistent with those values within 1.6 standard deviations. A resonance shape analysis has been performed in the resolved resonance region up to 181 eV and 307 eV, respectively for Gd and Gd, where on average, resonance parameters have been found in good agreement with evaluations. Above these energies and up to 1 keV, the observed resonance-like structure of the cross section has been analysed and characterised. From a statistical analysis of the observed neutron resonances we deduced: neutron strength function of 2. 01 (28) × 10 and 2. 17 (41) × 10 ; average total radiative width of 106.8(14) meV and 101.1(20) meV and s-wave resonance spacing 1.6(2) eV and 4.8(5) eV for n + Gd and n + Gd systems, respectively

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London