A new method for assessing the recyclability of powders within Powder Bed Fusion process

Recycling metallic powders used in the additive manufacturing (AM) process is essential for reducing the process cost, manufacturing time, energy consumption, and metallic waste. In this paper, the focus is on pore formation in recycled powder particles of stainless steel 316L during the selective laser melting process. We have introduced the concept of optimizing the powder bed's printing area in order to see the extent of the affected powders during the 3D-printing process. X-ray Computed Tomography (XCT) is used to characterize the pores inside the particles. The results from image processing of the tomography (rendered in 3D format) indicate a broader pore size distribution and a higher pore density in recycled powders compared to their virgin counterparts. To elucidate on this, the Electron Dispersion spectroscopy (EDX) analysis and Synchrotron-based Hard X-ray Photoelectron Spectroscopy (HAXPES) were performed to reveal the chemical composition distribution across the pore area and bulk of the recycled powder particles. Higher concentrations of Fe, Cr, and Ni were recorded on the interior wall of the pore in recycled particles and higher Mn, S and Si concentrations were recorded in the outer layer around the pore area and on the surface of the recycled particle. The pore formation in recycled powder is attributed to out-diffusion of Mn, S and Si to the outer surface as a result of the incident laser heat during the AM process due to higher electron affinity of such metallic elements to oxygenation. HAXPES analysis shows a higher MnO concentration around the pore area which impedes the in-diffusion of other elements into the bulk and thereby helps to creates a void. The inside wall of the pore area (dendrites), has a higher concentration of Fe and Cr oxide. We believe the higher pore density in recycled powders is due, at least in part to composition redistribution, promoted by laser heat during the AM process. Nanoindentation analyses on both virgin and recycled powder particles shows a lower hardness and higher effective modulus in the recycled powder particles attributed to the higher porosity in recycled powders

Eleanor Davies and the New Jerusalem

Eleanor Davies was a great believer in historical moments. In her first work—A Warning to the Dragon and All His Angels of 1625-she told readers that “The Lord is at the Dore.”1 This immanence of God made her watchful and purposeful, reading the signs in her daily life, counting days, weeks, and years because she believed that Christ would come again. His arrival had been predestined from the beginning of the world: “from the going forth of the Commandement, which is the beginning of the Creation to the building of the New Jerusalem, the second comming of Messiah, the Prince the Sonne of God, it shall be Seaven Weekes or Seaven Moneths.”2 For Davies, time was elastic, but history was absolute. What the biblical prophets (in this case Ezekiel) said would come to pass, really would come to pass, but their promises were oracular; they had complete authority but were also elusive. Davies accepted this. She knew that she was living in the latter days, but when it came to God’s final judgment, “the daye and houre knoweth no man.”3 God could not be known as such and what she called knowledge was a spiritual transformation that took place when “He powreth out his Spirit upon his hand-maidens,” like herself.4 This essay uses A Warning to the Dragon and Davies’ works of the 1630s and 1640s to examine her theology

Higher Structures in M-Theory

The key open problem of string theory remains its non-perturbative completion to M-theory. A decisive hint to its inner workings comes from numerous appearances of higher structures in the limits of M-theory that are already understood, such as higher degree flux fields and their dualities, or the higher algebraic structures governing closed string field theory. These are all controlled by the higher homotopy theory of derived categories, generalised cohomology theories, and $L_\infty$-algebras. This is the introductory chapter to the proceedings of the LMS/EPSRC Durham Symposium on Higher Structures in M-Theory. We first review higher structures as well as their motivation in string theory and beyond. Then we list the contributions in this volume, putting them into context.Comment: 22 pages, Introductory Article to Proceedings of LMS/EPSRC Durham Symposium Higher Structures in M-Theory, August 2018, references update

Mathematical practice, crowdsourcing, and social machines

The highest level of mathematics has traditionally been seen as a solitary endeavour, to produce a proof for review and acceptance by research peers. Mathematics is now at a remarkable inflexion point, with new technology radically extending the power and limits of individuals. Crowdsourcing pulls together diverse experts to solve problems; symbolic computation tackles huge routine calculations; and computers check proofs too long and complicated for humans to comprehend. Mathematical practice is an emerging interdisciplinary field which draws on philosophy and social science to understand how mathematics is produced. Online mathematical activity provides a novel and rich source of data for empirical investigation of mathematical practice - for example the community question answering system {\it mathoverflow} contains around 40,000 mathematical conversations, and {\it polymath} collaborations provide transcripts of the process of discovering proofs. Our preliminary investigations have demonstrated the importance of "soft" aspects such as analogy and creativity, alongside deduction and proof, in the production of mathematics, and have given us new ways to think about the roles of people and machines in creating new mathematical knowledge. We discuss further investigation of these resources and what it might reveal. Crowdsourced mathematical activity is an example of a "social machine", a new paradigm, identified by Berners-Lee, for viewing a combination of people and computers as a single problem-solving entity, and the subject of major international research endeavours. We outline a future research agenda for mathematics social machines, a combination of people, computers, and mathematical archives to create and apply mathematics, with the potential to change the way people do mathematics, and to transform the reach, pace, and impact of mathematics research.Comment: To appear, Springer LNCS, Proceedings of Conferences on Intelligent Computer Mathematics, CICM 2013, July 2013 Bath, U

A New Class of Safe Oligosaccharide Polymer Therapy To Modify the Mucus Barrier of Chronic Respiratory Disease

The host- and bacteria-derived extracellular polysaccharide coating of the lung is a considerable challenge in chronic respiratory disease and is a powerful barrier to effective drug delivery. A low molecular weight 12–15-mer alginate oligosaccharide (OligoG CF-5/20), derived from plant biopolymers, was shown to modulate the polyanionic components of this coating. Molecular modeling and Fourier transform infrared spectroscopy demonstrated binding between OligoG CF-5/20 and respiratory mucins. Ex vivo studies showed binding induced alterations in mucin surface charge and porosity of the three-dimensional mucin networks in cystic fibrosis (CF) sputum. Studies in Humans showed that OligoG CF-5/20 is safe for inhalation in CF patients with effective lung deposition and modifies the viscoelasticity of CF-sputum. OligoG CF-5/20 is the first inhaled polymer therapy, represents a novel mechanism of action and therapeutic approach for the treatment of chronic respiratory disease, and is currently in Phase IIb clinical trials for the treatment of CF

Breakdown of Mucin as Barrier to Digestive Enzymes in the Ischemic Rat Small Intestine

Loss of integrity of the epithelial/mucosal barrier in the small intestine has been associated with different pathologies that originate and/or develop in the gastrointestinal tract. We showed recently that mucin, the main protein in the mucus layer, is disrupted during early periods of intestinal ischemia. This event is accompanied by entry of pancreatic digestive enzymes into the intestinal wall. We hypothesize that the mucin-containing mucus layer is the main barrier preventing digestive enzymes from contacting the epithelium. Mucin breakdown may render the epithelium accessible to pancreatic enzymes, causing its disruption and increased permeability. The objective of this study was to investigate the role of mucin as a protection for epithelial integrity and function. A rat model of 30 min splanchnic arterial occlusion (SAO) was used to study the degradation of two mucin isoforms (mucin 2 and 13) and two epithelial membrane proteins (E-cadherin and toll-like receptor 4, TLR4). In addition, the role of digestive enzymes in mucin breakdown was assessed in this model by luminal inhibition with acarbose, tranexamic acid, or nafamostat mesilate. Furthermore, the protective effect of the mucin layer against trypsin-mediated disruption of the intestinal epithelium was studied in vitro. Rats after SAO showed degradation of mucin 2 and fragmentation of mucin 13, which was not prevented by protease inhibition. Mucin breakdown was accompanied by increased intestinal permeability to FITC-dextran as well as degradation of E-cadherin and TLR4. Addition of mucin to intestinal epithelial cells in vitro protected against trypsin-mediated degradation of E-cadherin and TLR4 and reduced permeability of FITC-dextran across the monolayer. These results indicate that mucin plays an important role in the preservation of the mucosal barrier and that ischemia but not digestive enzymes disturbs mucin integrity, while digestive enzymes actively mediate epithelial cell disruption

The Norwegian Mother, Father, and Child cohort study (MoBa) genotyping data resource: MoBaPsychGen pipeline v.1

BACKRGROUND: The Norwegian Mother, Father, and Child Cohort Study (MoBa) is a population-based pregnancy cohort, which includes approximately 114,500 children, 95,200 mothers, and 75,200 fathers. Genotyping of MoBa has been conducted through multiple research projects, spanning several years; using varying selection criteria, genotyping arrays, and genotyping centres. MoBa contains numerous interrelated families, which necessitated the implementation of a family-based quality control (QC) pipeline that verifies and accounts for diverse types of relatedness. METHODS: The MoBaPsychGen pipeline, comprising pre-imputation QC, phasing, imputation, and post-imputation QC, was developed based on current best-practice protocols and implemented to account for the complex structure of the MoBa genotype data. The pipeline includes QC on both single nucleotide polymorphism (SNP) and individual level. Phasing and imputation were performed using the publicly available Haplotype Reference Consortium release 1.1 panel as a reference. Information from the Medical Birth Registry of Norway and MoBa questionnaires were used to identify biological sex, year of birth, reported parent-offspring (PO) relationships, and multiple births (only available in the offspring generation). RESULTS: In total, 207,569 unique individuals (90% of the unique individuals included in the study) and 6,981,748 SNPs passed the MoBaPsychGen pipeline. The relatedness checks performed throughout the pipeline allowed identification of within-generation and across-generation first-degree, second-degree, and third-degree relatives. The individuals passing post-imputation QC comprised 64,471 families ranging in size from singletons to 84 unique individuals (singletons are included as families as other family members may not have been genotyped, imputed, or passed post-imputation QC). The relationships identified include 287 monozygotic twin pairs, 22,884 full siblings, 117,004 PO pairs, 23,299 second-degree relative pairs, and 10,828 third-degree relative pairs. DISCUSSION: MoBa contains a highly complex relatedness structure, with a variety of family structures including singletons, PO duos, full (mother, father, child) PO trios, nuclear families, blended families, and extended families. The availability of robustly quality-controlled genetic data for such a large cohort with a unique extended family structure will allow many novel research questions to be addressed. Furthermore, the MoBaPsychGen pipeline has potential utility in similar cohorts

Disk diffusion method for fluconazole susceptibility testing of Candida spp. isolates

Fil: Rodero, L. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Micología; Argentina.Fil: Córdoba, Susana. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Micología; Argentina.Fil: Vivot, W. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Micología; Argentina.Fil: Campo, M. Universidad Católica Argentina. Cátedra de Microbiología; Argentina.Fil: Corfield, P. Universidad Católica Argentina. Cátedra de Microbiología; Argentina.Fil: Olguín, C. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Micología; Argentina.Fil: Cuirolo, A. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Micología; Argentina.Fil: Soria, M. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Micología; Argentina.Fil: Guelfand, L. Universidad Católica Argentina. Cátedra de Microbiología; Argentina.Fil: Canteros, C. E. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Micología; Argentina.Fil: Davel, Graciela Odelsia. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Micología; Argentina.Fil: Red de Vigilancia de la Resistencia a los Antimicrobianos WHONET; Argentina.Se estudiaron 1193 aislamientos clínicos para estandarizar y evaluar un método de difusión con discos de fluconazol de lectura visual, que permita detectar levaduras sensibles al antifúngico. Las especies analizadas fueron: Candida albicans (n=584), Candida parapsilosis (n=196), Candida tropicalis (n=200), Candida glabrata (n=113), Candida krusei (n=50), Candida spp. y otras levaduras oportunistas (n=50). Los discos fueron manufacturados en el INEIANLIS “Dr. Carlos G. Malbrán”. Se midieron los halos de inhibición del crecimiento producidos por fluconazol y la concentración inhibitoria mínima (CIM) por el método de referencia M27-A2 modificado por EUCAST. Se establecieron los valores de corte del método de difusión en: ³ 16 mm para levaduras sensibles a fluconazol (CIM £ 8 μg/ml), entre 9 y 15 mm para sensibles dependientes de la dosis (CIM = 16-32 mg/ml) y £ 8 mm para resistentes (CIM ³ 64 μg/ml). El método de difusión tuvo 94,7% de concordancia con el de referencia, con 0,2% de errores very major y 0,3% de errores major. La reproducibilidad inter e intralaboratorio fue muy buena. Para detectar aislamientos sensibles a fluconazol, este método resulta confiable y de bajo costo; sin embargo, es conveniente que los aislamientos con halos £ 15 mm sean reevaluados por el método de referencia. (EN) In order to standardize and evaluate a disk diffusion method with visual reading to detect in vitro fluconazole susceptibility of yeast, 1193 clinical isolates were tested. These included 584 Candida albicans, 196 Candida parapsilosis, 200 Candida tropicalis, 113 Candida glabrata, 50 Candida krusei and 50 Candida spp. and other opportunistic yeasts. The disks were manufactured in the INEI-ANLIS “Dr. Carlos G. Malbrán”. The disk diffusion method results were compared to MIC results obtained by the reference CLSI M27-A2 broth microdilution method modified by EUCAST. The interpretative breakpoints for in vitro susceptibility testing of fluconazole were established at: zone diameter ³ 16 mm for MIC £ 8 μg/ml (susceptible isolates), between 9 and 15 mm for MIC = 16-32 mg/ml (susceptible dose-dependent isolates), and £ 8 mm for MIC ³ 64 μg/ml (resistant isolates). Overall agreement between the two methods was 94.7%, with 0.2% very major errors, and 0.3% major errors. Inter - and intralaboratory agreement was good. The disk diffusion method for drug susceptibility testing of Candida spp. isolates is inexpensive, reliable and reproducible. However, when the inhibition zone diameter is £ 15 mm, it is advisable to test the isolate by the reference microdilution method

Disk diffusion method for fluconazole susceptibility testing of Candida spp. isolates

Fil: Rodero, L. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Micología; Argentina.Fil: Córdoba, Susana. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Micología; Argentina.Fil: Vivot, W. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Micología; Argentina.Fil: Campo, M. Universidad Católica Argentina. Cátedra de Microbiología; Argentina.Fil: Corfield, P. Universidad Católica Argentina. Cátedra de Microbiología; Argentina.Fil: Olguín, C. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Micología; Argentina.Fil: Cuirolo, A. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Micología; Argentina.Fil: Soria, M. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Micología; Argentina.Fil: Guelfand, L. Universidad Católica Argentina. Cátedra de Microbiología; Argentina.Fil: Canteros, C. E. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Micología; Argentina.Fil: Davel, Graciela Odelsia. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Micología; Argentina.Fil: Red de Vigilancia de la Resistencia a los Antimicrobianos WHONET; Argentina.Se estudiaron 1193 aislamientos clínicos para estandarizar y evaluar un método de difusión con discos de fluconazol de lectura visual, que permita detectar levaduras sensibles al antifúngico. Las especies analizadas fueron: Candida albicans (n=584), Candida parapsilosis (n=196), Candida tropicalis (n=200), Candida glabrata (n=113), Candida krusei (n=50), Candida spp. y otras levaduras oportunistas (n=50). Los discos fueron manufacturados en el INEIANLIS “Dr. Carlos G. Malbrán”. Se midieron los halos de inhibición del crecimiento producidos por fluconazol y la concentración inhibitoria mínima (CIM) por el método de referencia M27-A2 modificado por EUCAST. Se establecieron los valores de corte del método de difusión en: ³ 16 mm para levaduras sensibles a fluconazol (CIM £ 8 μg/ml), entre 9 y 15 mm para sensibles dependientes de la dosis (CIM = 16-32 mg/ml) y £ 8 mm para resistentes (CIM ³ 64 μg/ml). El método de difusión tuvo 94,7% de concordancia con el de referencia, con 0,2% de errores very major y 0,3% de errores major. La reproducibilidad inter e intralaboratorio fue muy buena. Para detectar aislamientos sensibles a fluconazol, este método resulta confiable y de bajo costo; sin embargo, es conveniente que los aislamientos con halos £ 15 mm sean reevaluados por el método de referencia. (EN) In order to standardize and evaluate a disk diffusion method with visual reading to detect in vitro fluconazole susceptibility of yeast, 1193 clinical isolates were tested. These included 584 Candida albicans, 196 Candida parapsilosis, 200 Candida tropicalis, 113 Candida glabrata, 50 Candida krusei and 50 Candida spp. and other opportunistic yeasts. The disks were manufactured in the INEI-ANLIS “Dr. Carlos G. Malbrán”. The disk diffusion method results were compared to MIC results obtained by the reference CLSI M27-A2 broth microdilution method modified by EUCAST. The interpretative breakpoints for in vitro susceptibility testing of fluconazole were established at: zone diameter ³ 16 mm for MIC £ 8 μg/ml (susceptible isolates), between 9 and 15 mm for MIC = 16-32 mg/ml (susceptible dose-dependent isolates), and £ 8 mm for MIC ³ 64 μg/ml (resistant isolates). Overall agreement between the two methods was 94.7%, with 0.2% very major errors, and 0.3% major errors. Inter - and intralaboratory agreement was good. The disk diffusion method for drug susceptibility testing of Candida spp. isolates is inexpensive, reliable and reproducible. However, when the inhibition zone diameter is £ 15 mm, it is advisable to test the isolate by the reference microdilution method