Bricking: A New Slicing Method to Reduce Warping

AbstractFused Deposition Modeling (FDM) is the most used 3D printing technology. In this technology, 3D pieces are built warming and extruding thermoplastic through a nozzle. When the thermoplastic gets cold, internal stresses may generate deformations, mainly in corners. In this paper we describe a method for reduce these deformations (called warping), splitting pieces in hexagonal or squared bricks spatially locked. We have developed and tested an application that calculates the necessary GCODE to build the bricking piece directly, and we have measured a significant reduction in warp deformations

Additive Manufacturing with RepRap Methodology: Current Situation and Future Prospects

In February 2004, Adrian Bowyer, from the University of Bath, began an open initiative called RepRap, with the purpose of creating an open source rapid prototyping machine which, moreover, could replicate itself. This article analyzes the current status of the RepRap initiative, commenting the basic components of RepRap machines, the differences between the different 3D printers developed by the RepRap community so far, and the technical possibilities that opens this technology from the engineering point of view. In addition we propose some improvements that could be perfectly feasible in the short term. For this purpose, the assembly of a RepRap Mendel Prusa was performed, but with some modifications.Mechanical Engineerin

Caractérisation électrocinétique et thermodynamique de l'interface polypropylène/acides humiques

El presente trabajo muestra resultados acerca del comportamiento de las propiedades eléctricas y de la energía libre superficial en los procesos de adsorción de ácidos húmicos (AH) y diferentes electrolitos sobre las fibras de polipropileno. El propósito de este trabajo es conocer las propiedades de la superficie del polipropileno (PP) y los cambios que éstas experimentan cuando las fibras están en contacto con diferentes concentraciones de ácido húmico y diferentes cationes que son comunes en los suelos. Estos resultados son de gran interés para las aplicaciones del PP como geotextil. Los resultados muestran que el potencial zeta del sistema PP/AH decrece con la concentración de AH en disolución. Este hecho puede ser atribuido a la presencia de grupos carboxílicos COO- y hidroxilfenolicos presentes en la molécula de AH. Por otro lado, el pH de las disoluciones de ácido húmico tiene gran efecto en el potencial electrocinético del PP, debido probablemente a la presencia de los grupos de AH adsorbidos sobre la superficie del polipropileno. El análisis de la energía libre superficial de los sistemas PP/AH/electrolitos nos lleva a la conclusión de que el polipropileno es un material monopolar. Los valores bajos de la componente electrón donante, γ - , de la energía libre superficial nos llevan a la conclusión de que el material es fuertemente hidrófobo y que este carácter se incrementa con la adsorción de ácido húmico sobre las fibras.We present results about the electrokinetic properties and the behaviour of the surface free energy in the adsorption process of humic acid and different electrolytes onto polypropylene fibres. The aim of this investigation is to know the surface properties of polypropylene and the changes in these properties when these fibres are in contact with different concentrations of humic acid and different cations which are present in the ground for the application of the polypropylene fibres as geotextiles. The negative zeta potential of the Polypropylene / humic acid system decreases with the concentration of humic acid in solution. This fact can be attributed to the presence of both carboxyl COO- and phenolic hydroxyl groups in the macromolecule of humic acid. On the other hand, the pH of the humic acid solution greatly affects the electrokinetic potential of polypropylene fibres. The above groups of humic acid are responsible for the variation in the zeta potential of the polypropylene fibre with the pH of the liquid phase. The analysis of the surface free energy of the polypropylene/humic acid/electrolytes systems, leads to the conclusion that the polypropylene fibres it is presented as a monopolar material. The low values of the electrondonor component, γ - , of the surface free energy in the adsorption processes of humic acid and different electrolyte lead to the conclusion that this material is strongly hydrophobic and this character is increased by the adsorption of the humic acid onto the fibre.Le présent travail montre des résultats sur le comportement des propriétés électriques et de l'énergie libre superficielle dans les processus d'adsorption d'acides humiques (AC) et différents électrolytes sur les fibres de polypropylène. Le but de ce travail est de connaître les propriétés de la surface du polypropylène (PP) et les changements que celles-ci expérimentent quand les fibres sont en contact avec de différentes concentrations d'acide humique et de différents cations qui sont communs dans les sols. Ces résultats sont de grand intérêt pour les applications du PP comme géotextile Les résultats montrent que le potentiel zêta du système PP/AH diminue avec la concentration d'AH en dissolution. Ce fait peut être attribué à la présence de groupes carboxiliques COO- et hidroxilfenoliques présents dans la molécule d'AH. D'autre part, le pH des dissolutions d'acide humique a un grand effet dans le potentiel électrocinétic du PP, dû probablement à la présence des groupes d'AH adsorbés sur la surface du polypropylène. L'analyse de l'énergie libre superficielle des systèmes PP/AH/électrolytes nous apporte à la conclusion que le polypropylène est un matériel monopolaire. Les valeurs basses de la composante électron donneuse, de l'énergie libre superficielle nous apportent à la conclusion que le matériel est hydrophobe de façon forte et que ce caractère est augmenté avec l'adsorption d'acide humique sur les fibres.Peer Reviewe

Radiative Corrections to Neutralino and Chargino Masses in the Minimal Supersymmetric Model

We determine the neutralino and chargino masses in the MSSM at one-loop. We perform a Feynman diagram calculation in the on-shell renormalization scheme, including quark/squark and lepton/slepton loops. We find generically the corrections are of order 6%. For a 20 GeV neutralino the corrections can be larger than 20%. The corrections change the region of $\mu,\ M_2,\ \tan\beta$ parameter space which is ruled out by LEP data. We demonstrate that, e.g., for a given $\mu$ and $\tan\beta$ the lower limit on the parameter $M_2$ can shift by 20 GeV.Comment: 11 pages, JHU-TIPAC-930030, PURD-TH-93-13, uses epsf.sty, 6 uuencoded postscript figures, added one sentence and a referenc

Chromosomal localization of the genes encoding the p50/p105 subunits of NF-κB (NFKB2) and the IκB/MAD-3 (NFKBI) inhibitor of NF-κB to 4q24 and 14q13, respectively

The regulation of expression of a variety of genes involved in immune function, inflammation, and cellular growth control, as well as control of expression of certain viruses such as the human immunodeficiency virus (HIV), is dependent on the transcription factor NF-κB. In many cells, NF-κB is found in the cytoplasm where it is associated with an inhibitor protein known as IκB. Recently the genes encoding the p50 and p65 subunits of NF-κB, as well as one form of IκB/MAD-3 (NFKBI), have been cloned. As part of our goal to determine the chromosomal organization of members of the REL/NFKB family, as well as their inhibitors, we localized the NFKBp50/p105 (NFKB2) and IκB/MAD-3 (NFKBI) genes to human chromosome bands 4q24 and 14q13, respectively

Scattering of elastic waves by periodic arrays of spherical bodies

We develop a formalism for the calculation of the frequency band structure of a phononic crystal consisting of non-overlapping elastic spheres, characterized by Lam\'e coefficients which may be complex and frequency dependent, arranged periodically in a host medium with different mass density and Lam\'e coefficients. We view the crystal as a sequence of planes of spheres, parallel to and having the two dimensional periodicity of a given crystallographic plane, and obtain the complex band structure of the infinite crystal associated with this plane. The method allows one to calculate, also, the transmission, reflection, and absorption coefficients for an elastic wave (longitudinal or transverse) incident, at any angle, on a slab of the crystal of finite thickness. We demonstrate the efficiency of the method by applying it to a specific example.Comment: 19 pages, 5 figures, Phys. Rev. B (in press

Complementarity of the CERN Large Hadron Collider and the e+e−e^+e^- International Linear Collider

The next-generation high-energy facilities, the CERN Large Hadron Collider (LHC) and the prospective $e^+e^-$ International Linear Collider (ILC), are expected to unravel new structures of matter and forces from the electroweak scale to the TeV scale. In this report we review the complementary role of LHC and ILC in drawing a comprehensive and high-precision picture of the mechanism breaking the electroweak symmetries and generating mass, and the unification of forces in the frame of supersymmetry.Comment: 14 pages, 17 figures, to be published in "Supersymmetry on the Eve of the LHC", a special volume of European Physical Journal C, Particles and Fields (EPJC) in memory of Julius Wes

Structural Equation Model (SEM) of stroke mortality in Spanish inpatient hospital settings: The role of individual and contextual factors

Introduction: Traditionally, predictive models of in-hospital mortality in ischemic stroke have focused on individual patient variables, to the neglect of in-hospital contextual variables. In addition, frequently used scores are betters predictors of risk of sequelae than mortality, and, to date, the use of structural equations in elaborating such measures has only been anecdotal. Aims: The aim of this paper was to analyze the joint predictive weight of the following: (1) individual factors (age, gender, obesity, and epilepsy) on the mediating factors (arrhythmias, dyslipidemia, hypertension), and ultimately death (exitus); (2) contextual in-hospital factors (year and existence of a stroke unit) on the mediating factors (number of diagnoses, procedures and length of stay, and re-admission), as determinants of death; and (3) certain factors in predicting others. Material and Methods: Retrospective cohort study through observational analysis of all hospital stays of Diagnosis Related Group (DRG) 14, non-lysed ischemic stroke, during the time period 2008¿2012. The sample consisted of a total of 186,245 hospital stays, taken from the Minimum Basic Data Set (MBDS) upon discharge from Spanish hospitals. MANOVAs were carried out to establish the linear effect of certain variables on others. These formed the basis for building the Structural Equation Model (SEM), with the corresponding parameters and restrictive indicators. Results: A consistent model of causal predictive relationships between the postulated variables was obtained. One of the most interesting effects was the predictive value of contextual variables on individual variables, especially the indirect effect of the existence of stroke units on reducing number of procedures, readmission and in-hospital mortality. Conclusion: Contextual variables, and specifically the availability of stroke units, made a positive impact on individual variables that affect prognosis and mortality in ischemic stroke. Moreover, it is feasible to determine this impact through the use of structural equation methodology. We analyze the methodological and clinical implications of this type of study for hospital policies

Follow-up of loci from the International Genomics of Alzheimer's Disease Project identifies TRIP4 as a novel susceptibility gene

To follow-up loci discovered by the International Genomics of Alzheimer's Disease Project, we attempted independent replication of 19 single nucleotide polymorphisms (SNPs) in a large Spanish sample (Fundació ACE data set; 1808 patients and 2564 controls). Our results corroborate association with four SNPs located in the genes INPP5D, MEF2C, ZCWPW1 and FERMT2, respectively. Of these, ZCWPW1 was the only SNP to withstand correction for multiple testing (P=0.000655). Furthermore, we identify TRIP4 (rs74615166) as a novel genome-wide significant locus for Alzheimer's disease risk (odds ratio=1.31; confidence interval 95% (1.19-1.44); P=9.74 × 10 - 9)