Design of hard surfaces with metal (Hf/V) nitride multinanolayers

Physical properties as mechanical and tribological evolution on 4140 steel surfaces coated with hafnium nitride/vanadium nitride [HfN/VN]n multinanolayered systems deposited in various bilayer periods via magnetron sputtering has been exhaustively studied in this work. The coatings have been characterized in terms of structural, chemical, morphological, mechanical, and tribological properties by X-ray diffraction, X-ray photoelectron spectroscopy, atomic force microscopy, scanning and transmission electron microscopies, nanoindentation, pin-on-disc and scratch tests. Moreover, the failure mode mechanisms were observed via scanning electron microscopy. The preferential growth in the face-centered cubic (111) crystal structure for [HfN/VN]n multilayered coatings have been shown by X-ray diffraction results. The best enhancement of the mechanical behavior has been obtained when the bilayer period was 15 nm (n = 80), yielding the highest hardness (37 GPa) and elastic modulus was (351 GPa). The values of the hardness and elastic modulus were 1.48 and 1.32 times higher than the coating with n = 1, respectively, as well as the lowest friction coefficient (~ 0.15) and the highest critical load (72 N). These results indicated significant enhancements in mechanical, tribological, and adhesion properties, compared to HfN/VN multilayered systems with bilayer period of 1200 nm (n = 1). The hardness and toughness enhancement in the multilayered coatings could be attributed to the different mechanisms that produce the layer formation with nanometric thickness due to the number of interfaces acting as obstacles for crack deflection and dissipation of crack energy. Due to the emergent characteristics of the synthesized multinanolayered material, the developed adaptive coating could be considered as higher ordered tool machining systems, capable of sustaining extreme operating conditions for industrial applications.Фізичні властивості як механічні і трибологічні зміни на поверхні сталі марки 4140 з покриттям із нанобагатошарових систем нітриду гафнію/нітриду ванадію [HfN/VN]n, нанесених магнетронним розпиленням з різними проміжками між двома шарами, були ретельно вивчені в цій роботі. Структурні, хімічні, морфологічні і трибологічні властивості покриттів визначали дифракцією рентгенівських променів, фотоелектронною рентгенівською спектроскопією, атомно-силовою мікроскопією, растровою та просвічувальною електронною мікроскопією, наноіндентуванням, методом “штифт на крузі” і випробуванням дряпанням. Крім того, механізми відмов спостерігали за допомогою растрової електронної мікроскопії. Результати дифракції рентгенівських променів показали краще зростання (111) граніцентрованої кристалічної структури для багатошарових покриттів [HfN/VN]n. Максимальне підвищення механічних характеристик було досягнуто при товщині бішару HfN/VN, що дорівнював 15 нм (число шарів 80), твердість складала 37 ГПа, а модуль пружності – 351 ГПа. Ці значення твердості і модуля пружності були вище, ніж у покриття з n = 1 (в 1,48 і 1,32 рази відповідно), також це багатошарове покриття мало найнижчий (~ 0,15) коефіцієнт тертя і найвище (72 Н) критичне навантаження. Ці результати показали значне поліпшення механічних, трибологічних і адгезійних властивостей порівняно з HfN/VN багатошарової системою з товщиною бішару 1200 нм (n = 1). Підвищення твердості і в’язкості руйнування багатошарових покриттів може бути пояснено різними механізмами утворювання шарів нанометричної товщини, зумовлених кількістю меж розділу, що діють як перешкоди для відхилення тріщини і розсіювання її енергії. Завдяки покращеним характеристикам синтезованого багатошарового матеріалу, розроблене адаптивне покриття можна розглядати як більш високо впорядковану інструментальну систему обробки, здатну підтримувати екстремальні робочі умови при використанні в промисловості.Физические свойства как механические и трибологические изменения на поверхности стали марки 4140 с покрытием из наномногослойных систем нитрида гафния/нитрида ванадия [HfN/VN]n, нанесенных магнетронным распылением с различными промежутками между двумя слоями, были тщательно изучены в этой работе. Структурные, химические, морфологические и трибологические свойства покрытий определяли дифракцией рентгеновских лучей, фотоэлектронной рентгеновской спектроскопией, атомно-силовой микроскопией, растровой и просвечивающей электронной микроскопией, наноиндентированием, методом “штифт на круге” и испытания царапаньем. Кроме того, механизмы отказов наблюдали посредством растровой электронной микроскопии. Результаты дифракции рентгеновских лучей показали предпочтительный рост (111) гранецентрированной кристаллической структуры для многослойных покрытий [HfN/VN]n. Максимальное повышение механических характеристик было достигнуто при толщине бислоя HfN/VN равной 15 нм (число слоев 80), твердость была равна 37 ГПа, а модуль упругости – 351 ГПа. Эти значения твердости и модуля упругости были выше, чем у покрытия с n = 1 (в 1,48 и 1,32 раза соответственно), также у этого многослойного покрытия был самый низкий (~ 0,15) коэффициент трения и самая высокая (72 Н) критическая нагрузка. Эти результаты показали значительное улучшение механических, трибологических и адгезионных свойств по сравнению с HfN/VN многослойной системой с толщиной бислоя 1200 нм (n = 1). Повышение твердости и вязкости разрушения многослойных покрытий может быть объяснено различными механизмами образования слоев нанометрической толщины, обусловленных количеством границ раздела, действующих как препятствия для отклонения трещины и рассеяния ее энергии. Благодаря улучшенным характеристикам синтезированного многонанослойного материала, разработанное адаптивное покрытие можно рассматривать как более высоко упорядоченную инструментальную обрабатывающую систему, способную поддерживать экстремальные рабочие условия при использовании в промышленности

Mechanical and tribological properties of V–C–N coatings as a function of applied bias voltage

The aim of this work is to determine the mechanical and tribological behavior of V–C–N coatings deposited on industrial steel substrates (AISI 8620) by using carbon–nitride coatings as a protective materials.Метою роботи було визначення механічної та трибологічної поведінки V–C–N-покриттів, осаджених на сталеві (AISI 8620) підкладки, для використання як захисні матеріали.Целью работы было определение механического и трибологического поведения V–C–N-покрытий, осажденных на стальные (AISI 8620) подложки, для использования как защитные материалы.This research was supported by Universidad Militar Nueva Granada, contract number ING-1775-2015, Universidad del Quindío and the CIC biomaGUNE, Platform Manager – Surface Analysis and Fabrication, Spain

Wealth, Social Protection Programs, and Child Labor in Colombia: A Cross-sectional Study

This article has 3 main objectives: (1) to assess the prevalence of child labor in Colombia, (2) to identify factors associated with child labor, and (3) to determine whether social protection programs have an association with the prevalence of child labor in the country. Using a cross-sectional study with data from the Colombian Demographic and Health Survey 2010, a working child was defined as a child who worked during the week prior to the survey in an activity other than household chores. Through descriptive statistics, bivariate analysis, and multivariate regressions, it was found that child labor was associated with gender (boys were more likely to work), older age, ethnicity (children from indigenous communities were more likely to be workers), school dropout, disability (children with disabilities were less likely to be working), subsidized health social security system membership, and lower number of years of mother’s schooling. Furthermore, the results of this study suggest that children beneficiaries of the subsidy Familias en Acción were less likely to be working and that social protection programs were more effective to reduce child labor when targeting the lowest wealth quintiles of the Colombian population. © The Author(s) 2018

BF models, Duality and Bosonization on higher genus surfaces

The generating functional of two dimensional $BF$ field theories coupled to fermionic fields and conserved currents is computed in the general case when the base manifold is a genus g compact Riemann surface. The lagrangian density $L=dB{\wedge}A$ is written in terms of a globally defined 1-form $A$ and a multi-valued scalar field $B$. Consistency conditions on the periods of $dB$ have to be imposed. It is shown that there exist a non-trivial dependence of the generating functional on the topological restrictions imposed to $B$. In particular if the periods of the $B$ field are constrained to take values $4\pi n$, with $n$ any integer, then the partition function is independent of the chosen spin structure and may be written as a sum over all the spin structures associated to the fermions even when one started with a fixed spin structure. These results are then applied to the functional bosonization of fermionic fields on higher genus surfaces. A bosonized form of the partition function which takes care of the chosen spin structure is obtainedComment: 17 page

Free Abelian 2-Form Gauge Theory: BRST Approach

We discuss various symmetry properties of the Lagrangian density of a four (3 + 1)-dimensional (4D) free Abelian 2-form gauge theory within the framework of Becchi-Rouet-Stora-Tyutin (BRST) formalism. The present free Abelian gauge theory is endowed with a Curci-Ferrari type condition which happens to be a key signature of the 4D non-Abelian 1-form gauge theory. In fact, it is due to the above condition that the nilpotent BRST and anti-BRST symmetries of the theory are found to be absolutely anticommuting in nature. For our present 2-form gauge theory, we discuss the BRST, anti-BRST, ghost and discrete symmetry properties of the Lagrangian densities and derive the corresponding conserved charges. The algebraic structure, obeyed by the above conserved charges, is deduced and the constraint analysis is performed with the help of the physicality criteria where the conserved and nilpotent (anti-)BRST charges play completely independent roles. These physicality conditions lead to the derivation of the above Curci-Ferrari type restriction, within the framework of BRST formalism, from the constraint analysis.Comment: LaTeX file, 21 pages, journal referenc

Consenso colombiano de atención, diagnóstico y manejo de la infección por SARS-COV-2/COVID-19 en establecimientos de atención de la salud Recomendaciones basadas en consenso de expertos e informadas en la evidencia

The “Asociación Colombiana de Infectología” (ACIN) and the “Instituto de Evaluación de Nuevas Tecnologías de la Salud” (IETS) created a task force to develop recommendations for Covid 19 health care diagnosis, management and treatment informed, and based, on evidence. Theses reccomendations are addressed to the health personnel on the Colombian context of health services. © 2020 Asociacion Colombiana de Infectologia. All rights reserved

Global, regional, and national comparative risk assessment of 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks, 1990-2015: A systematic analysis for the Global Burden of Disease Study 2015

Background: The Global Burden of Diseases, Injuries, and Risk Factors Study 2015 provides an up-to-date synthesis of the evidence for risk factor exposure and the attributable burden of disease. By providing national and subnational assessments spanning the past 25 years, this study can inform debates on the importance of addressing risks in context. Methods: We used the comparative risk assessment framework developed for previous iterations of the Global Burden of Disease Study to estimate attributable deaths, disability-adjusted life-years (DALYs), and trends in exposure by age group, sex, year, and geography for 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks from 1990 to 2015. This study included 388 risk-outcome pairs that met World Cancer Research Fund-defined criteria for convincing or probable evidence. We extracted relative risk and exposure estimates from randomised controlled trials, cohorts, pooled cohorts, household surveys, census data, satellite data, and other sources. We used statistical models to pool data, adjust for bias, and incorporate covariates. We developed a metric that allows comparisons of exposure across risk factors—the summary exposure value. Using the counterfactual scenario of theoretical minimum risk level, we estimated the portion of deaths and DALYs that could be attributed to a given risk. We decomposed trends in attributable burden into contributions from population growth, population age structure, risk exposure, and risk-deleted cause-specific DALY rates. We characterised risk exposure in relation to a Socio-demographic Index (SDI). Findings: Between 1990 and 2015, global exposure to unsafe sanitation, household air pollution, childhood underweight, childhood stunting, and smoking each decreased by more than 25%. Global exposure for several occupational risks, high body-mass index (BMI), and drug use increased by more than 25% over the same period. All risks jointly evaluated in 2015 accounted for 57·8% (95% CI 56·6–58·8) of global deaths and 41·2% (39·8–42·8) of DALYs. In 2015, the ten largest contributors to global DALYs among Level 3 risks were high systolic blood pressure (211·8 million [192·7 million to 231·1 million] global DALYs), smoking (148·6 million [134·2 million to 163·1 million]), high fasting plasma glucose (143·1 million [125·1 million to 163·5 million]), high BMI (120·1 million [83·8 million to 158·4 million]), childhood undernutrition (113·3 million [103·9 million to 123·4 million]), ambient particulate matter (103·1 million [90·8 million to 115·1 million]), high total cholesterol (88·7 million [74·6 million to 105·7 million]), household air pollution (85·6 million [66·7 million to 106·1 million]), alcohol use (85·0 million [77·2 million to 93·0 million]), and diets high in sodium (83·0 million [49·3 million to 127·5 million]). From 1990 to 2015, attributable DALYs declined for micronutrient deficiencies, childhood undernutrition, unsafe sanitation and water, and household air pollution; reductions in risk-deleted DALY rates rather than reductions in exposure drove these declines. Rising exposure contributed to notable increases in attributable DALYs from high BMI, high fasting plasma glucose, occupational carcinogens, and drug use. Environmental risks and childhood undernutrition declined steadily with SDI; low physical activity, high BMI, and high fasting plasma glucose increased with SDI. In 119 countries, metabolic risks, such as high BMI and fasting plasma glucose, contributed the most attributable DALYs in 2015. Regionally, smoking still ranked among the leading five risk factors for attributable DALYs in 109 countries; childhood underweight and unsafe sex remained primary drivers of early death and disability in much of sub-Saharan Africa. Interpretation: Declines in some key environmental risks have contributed to declines in critical infectious diseases. Some risks appear to be invariant to SDI. Increasing risks, including high BMI, high fasting plasma glucose, drug use, and some occupational exposures, contribute to rising burden from some conditions, but also provide opportunities for intervention. Some highly preventable risks, such as smoking, remain major causes of attributable DALYs, even as exposure is declining. Public policy makers need to pay attention to the risks that are increasingly major contributors to global burden. Funding: Bill & Melinda Gates Foundation

Volume I. Introduction to DUNE

The preponderance of matter over antimatter in the early universe, the dynamics of the supernovae that produced the heavy elements necessary for life, and whether protons eventually decay—these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our universe, its current state, and its eventual fate. The Deep Underground Neutrino Experiment (DUNE) is an international world-class experiment dedicated to addressing these questions as it searches for leptonic charge-parity symmetry violation, stands ready to capture supernova neutrino bursts, and seeks to observe nucleon decay as a signature of a grand unified theory underlying the standard model. The DUNE far detector technical design report (TDR) describes the DUNE physics program and the technical designs of the single- and dual-phase DUNE liquid argon TPC far detector modules. This TDR is intended to justify the technical choices for the far detector that flow down from the high-level physics goals through requirements at all levels of the Project. Volume I contains an executive summary that introduces the DUNE science program, the far detector and the strategy for its modular designs, and the organization and management of the Project. The remainder of Volume I provides more detail on the science program that drives the choice of detector technologies and on the technologies themselves. It also introduces the designs for the DUNE near detector and the DUNE computing model, for which DUNE is planning design reports. Volume II of this TDR describes DUNE\u27s physics program in detail. Volume III describes the technical coordination required for the far detector design, construction, installation, and integration, and its organizational structure. Volume IV describes the single-phase far detector technology. A planned Volume V will describe the dual-phase technology

A multicentre outcome analysis to define global benchmarks for donation after circulatory death liver transplantation

Cellular mechanisms in basic and clinical gastroenterology and hepatolog