bluuebunny/crossref_metadata_2025 huggingface dataset:
Nuclease-mediated depletion biases in ribosome footprint profiling libraries
Authors: Zinshteyn Boris , Wangen Jamie R. , Hua Boyang , Green Rachel
Published: June 2020

Ribosome footprint profiling is a high-throughput sequencing–based technique that provides detailed and global views of translation in living cells. An essential part of this technology is removal of unwanted, normally very abundant, ribosomal RNA sequences that dominate libraries and increase sequencing costs. The most effective commercial solution (Ribo-Zero) has been discontinued as a standalone product and a number of new, experimentally distinct commercial applications have emerged on the market. Here we evaluated several commercially available alternatives designed for RNA-seq of human samples and find them generally unsuitable for ribosome footprint profiling. We instead recommend the use of custom-designed biotinylated oligos, which were widely used in early ribosome profiling studies. Importantly, we warn that depletion solutions based on targeted nuclease cleavage significantly perturb the high-resolution information that can be derived from the data, and thus do not recommend their use for any applications that require precise determination of the ends of RNA fragments.
Valuation of the rights requirements (debt receivable): theory and practice
Authors: Sutyagin Vladislav
Published: June 2020

The textbook divides the concepts used in the assessment, — the right to claim the liability (debt), accounts receivable. Solved what is the object of evaluation from the point of view of the legislation on appraisal activity. Describes the specifics of the receivable and its financing in the company. The peculiarities of accounting of accounts receivable. The questions of inventory of receivables, its recognition, the used chart of accounts and procedures for cancellation. The features of the procedure of the analysis of the quality of receivables. Considers the current methodology of assessment of claims. Attention is paid to issues of mass valuation of receivables, the evaluation of business value, as well as the problem of calculating the discount rate.
Meets the requirements of Federal state educational standards of higher education of the last generation.
For students of higher educational institutions enrolled in the fields of study within the bachelor — 38.03.01 "Economics", within the master's program — 38.04.01 "Economy" and 38.04.08 "Finance and credit", and also for students of professional retraining programs "Valuation of enterprise (business)".
Moscow metropolis: improving the foreign economic activities
Authors: Gogiberidze Lidiya
Published: June 2020

This monograph examines the phenomenon of innovation-oriented foreign economic activities of the Moscow megalopolis: its problems, opportunities, risks, ways of development.
Addressed to a wide circle of managers, experts, scientists, and practitioners interested in the expansion and improvement of foreign economic relations of capital.
Secure Text Messaging in Healthcare: Latent Threats and Opportunities to Improve Patient Safety
Authors: Hagedorn Philip A , Singh Amit , Luo Brooke , Bonafide Christopher , Simmons Jeffrey M
Published: June 2020

Over the past two decades, physicians and nurses practicing in hospital settings have faced an onslaught of challenges in communication, an area frequently cited as critical to providing safe and effective care to patients.1-3 Communication needs have increased significantly as hospitalized patients have become more acute, complex, and technology-dependent, requiring larger healthcare teams comprising subspecialists across multiple disciplines spread across increasingly larger inpatient facilities.4 During this same period, the evolution of mobile phones has led to dramatic shifts in personal communication patterns, with asynchronous text messaging replacing verbal communication.5-7
Changes in plasma biochemical parameters and hormones during transition period in Beetal goats carrying single and twin fetus
Authors: Madan Jyotsana , Sindhu Sonia , Rose Manoj Kumar
Published: June 2020

Aim: The study was undertaken to find out the changes in biochemical and hormonal profile during transition period in single- and twin-bearing Beetal goats.

Materials and Methods: Beetal goats are reared in North India for milk and meat purposes, popularly called poor man's cow, serving as a source of livelihood. The present study was conducted on Beetal goats, maintained at a goat farm, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, for characterization of plasma biochemical and hormonal changes during transitional phase in pregnant goats carrying single and twin fetus. The animals selected were expected to have parturition at the same time, to avoid environmental variation effects, and divided into two groups: Group 1 (carrying single fetus, n=14) and Group 2 (twin fetus, n=6). Blood samples were collected from goats prepartum (–30 days and –15 days), 0 day, and postpartum +15 days and +30 days, and plasma was separated for the analysis of biochemical metabolites and hormones by commercially available kits.

Results: Analysis of data revealed a significant decrease in triglyceride and cholesterol concentration during postpartum days. A significant increase in alanine aminotransferase (ALT) concentration was observed at the day of parturition. Furthermore, there was a significant (p≤0.05) decrease in ALT and aspartate aminotransferase concentration in goats at the 15th day and 30th day after parturition in both groups. A significant (p≤0.05) lower concentration of total protein and globulins was observed during late pregnancy and on the day of parturition, with a subsequent elevation during postpartum period (15 days and 30 days). Progesterone concentration was highest at –30 days prepartum and decreased sharply at parturition and thereafter postpartum, both in single- and twin-bearing goats. Progesterone level was lower in twin-bearing goats as compared to single-bearing goats at 0 day and postpartum days. No significant changes were observed in sodium, potassium, and chloride concentration during transitional period in goats.

Conclusion: Transition period blood metabolite profile changes due to physiological need of mother and fetus were more prominent in metabolites regulating energy requirements and in goats bearing twin fetus.
In vitro germination of pollen grains of three native species from Pampa biome with ornamental potential
Authors: Tedesco Marília , Alves Luciano da Silva , Avrella Eduarda Demari , Simioni Carine , Schafer Gilmar
Published: June 2020

The aim of this work was to verify the in vitro germination of pollen grains of Angelonia integerrima L., Campomanesia aurea O. Berg and Sesbania punicea (Cav.) Benth in different culture medium and temperatures. For this purpose, flower buds from which pollen was collected and sprayed on plates containing the three evaluated culture medium: M1 - agar and sucrose; M2 - agar, sucrose and H3BO3; M3 - agar, sucrose, H3BO3, Ca(NO3), MgSO4 and KNO3; and two incubation temperatures (20 °C and 30 °C). Data was subjected to analysis of variance after its transformation to square root and means were compared by Fisher’s test (LSD). For the three species, the temperature of 30 ºC provided the highest percentage of pollen grain germination. For A. integerrima, M1 and M3 promoted the highest germination percentages (40.7 % and 56.5 %, respectively). On the other hand, for C. aurea, M2 provided the highest germination average (43.7 %). At last for S. punicea, M3 was the one that provided the highest average (31.62 %). It was concluded that the evaluated species differ in micronutrient requirements for in vitro germination of pollen grains. The temperature of 30 °C was suitable for all three species.
Participação social no contexto da Atenção Primária à Saúde
Authors: Oliveira Ana Maria Caldeira , Dallari Sueli Gandolfi
Published: June 2020

As Comissões Locais de Saúde - CLS, em cada Unidade Básica de Saúde – UBS, constituem-se espaços participativos do Sistema Único de Saúde de Belo Horizonte –SUS/BH, mais próximos da população. O objetivo do artigo é analisar o impacto da prática participativa exercida pelas CLS na dinâmica de funcionamento das UBS. Foram entrevistados 21 Conselheiros Locais de Saúde utilizando-se a técnica de entrevistas baseada em roteiro semiestruturado, sendo os dados analisados pela técnica do Discurso do Sujeito Coletivo. Verificou-se nos discursos dos usuários o reconhecimento das melhorias advindas das CLS. Os trabalhadores não reconhecem as melhorias resultantes das CLS. Já os gestores, através de uma participação compulsória percebem a importância desse fórum para os usuários. Conclui-se que a prática participativa exercida pelas CLS impacta positivamente a vida da UBS, pois através do exercício da cidadania e do fomento de uma cultura política democrática tem-se a possibilidade de formar cidadãos mais informados e conscientes, em busca do direito a ter direitos.
Anabolizantes
Authors: Moraes Gabriela Silva , Almeida Paulo Henrique Ribeiro Fernandes , Lemos Lucas Brasileiro , Lemos Gisele da Silveira
Published: June 2020

O trabalho teve como objetivo avaliar os erros de prescrição e dispensação de medicamentos anabolizantes em uma farmácia comunitária no sudoeste da Bahia. Trata-se de um estudo transversal, descritivo-analítico, realizado com auxílio de um formulário padronizado, o qual avaliou a completude e legibilidade das receitas de controle especial de anabolizantes, dispensadas durante o período de abril de 2014 a abril de 2018. Os dados coletados foram tabulados e analisados no software Epidata 3.1 e SPSS na sua versão 21.0, respectivamente. Adotando um nível de significância p<0,05. Foram analisadas 128 prescrições de medicamentos anabolizantes identificando um total de 691 erros, sendo as falhas na prescrição apresentadas como de maior ocorrência (76%): omissão do endereço do paciente, duração de tratamento e forma farmacêutica. A prescrição de Durateston® foi predominante em 67,2% das receitas e dentre as especialidades prescritoras sobressaíram às prescrições de médicos em relação a cirurgião-dentista e médico veterinário. Sobre o processo de dispensação, foi notada a ausência da assinatura ou carimbo do farmacêutico em 100% das receitas. As avaliações das prescrições demonstraram a ocorrência de erros tanto no processo de prescrição como no de dispensação, evidenciando a importância da completude das prescrições e adequação as legislações a fim de promover a segurança do paciente.
Financiamento federal da atenção básica à saúde no SUS
Authors: Amorim Danilo Aquino , Mendes Aquilas
Published: June 2020

Este estudo tem como objetivo analisar o financiamento federal da atenção básica à saúde no SUS e os aspectos que conformaram o financiamento, as transferências de recursos e as características desse nível de atenção ao longo dos 31 anos de existência do SUS. Tratou-se de uma revisão narrativa da literatura, norteada pela análise do financiamento federal da atenção básica. Foi utilizado o Portal Regional da BVS (Biblioteca Virtual em Saúde) para pesquisa e recuperação das publicações. Após a aplicação dos critérios de inclusão e exclusão, 10 publicações foram incluídas nessa revisão. Há consenso na literatura de que a atenção básica representa a principal estratégia de transformação do modelo de atenção à saúde a partir da criação do SUS. No entanto, os autores apresentam visões distintas sobre como o financiamento federal e as formas de transferência de recursos entre os entes federativos impactaram sobre a implantação da atenção básica no Brasil.
Efeitos das políticas econômicas restritivas sobre a condição de saúde dos brasileiros
Authors: Souza Júnior Milton Aparecido , Mendes Aquilas
Published: June 2020

Identificar a descrição na literatura nacional dos efeitos das políticas econômicas restritivas adotadas pelo Brasil, especialmente a partir de 2015, sobre os principais indicadores das condições de saúde dos brasileiros. Revisão narrativa da literatura, realizada com base em pesquisa na Biblioteca Virtual em Saúde Pública – BVS. A busca baseou-se na técnica de funil, combinando-se diversos descritores relacionados ao tema. No total, obteve-se 19 publicações incluídas nesta revisão, disponíveis gratuitamente e que atingiram os critérios estabelecidos. Os principais temas trabalhados no material bibliográfico dizem respeito a análises relacionadas ao contexto de crise econômica e restrições e suas implicações na saúde bucal dos brasileiros e em taxas de mortalidade geral, materna, infantil, precoce, tardia e pós-neonatal. Juntas, as temáticas relacionadas a problemas odontológicos e à mortalidade figuram em 79% dos artigos analisados. As principais variáveis explicativas associadas aos indicadores de saúde foram: renda familiar (citada em 42% das publicações) e gasto público per capita e/ou como proporção ao Produto Interno Bruto (26%). Em um momento em que o Sistema Único de Saúde passa a ser ameaçado pela adoção de ajustes recessivos, há que se compreender, pelas lições depreendidas da experiência de outros países, que o Brasil tende a assumir o risco de se tornar mais um exemplo de como a escolha pela redução ou corte de gastos na área da saúde pode comprometer a saúde e até a vida dos brasileiros.
Equipamentos de proteção individual para prevenção de infecção por Sars-Cov-2
Authors: Rosa de Sousa Neto Antonio , Batista Bortoluzzi Bruno , Reis Joaquim de Freitas Daniela
Published: June 2020

Frente a pandemia ocasionada por COVID-19, faz-se essencial a adoção de medidas de prevenção e controle de infecção. Realizou-se pesquisa bibliográfica e de diretrizes de sociedades médicas sobre as indicações de uso dos Equipamentos de Proteção Individual por parte dos profissionais que atuam na assistência hospitalar. Existem uma série de equipamentos que devem ser adotados por profissionais de saúde, alguns deles já com recomendações específicas para reutilização, dada sua escassez em função da pandemia. Faz-se necessário que os profissionais de saúde se mantenham atualizados e trabalhem conforme as recomendações nacionais e mundiais de saúde.
ETIKA DALAM ISLAM: TELAAH KRITIS TERHADAP PEMIKIRAN IBN MISKAWAIH
Authors: Efendi Rusfian
Published: June 2020

The flow of ethical thought does not stop at Western Philosophy. Ethical thinking also colors and influences the discourse of thought in Islamic Philosophy. Differences in the style of Western Philosophy and Islamic Philosophy have a significant impact that has caused a debate about the expertise and courage of a Muslim thinker in adopting Greek ethical thought by not leaving the corridors of Islamic teachings. A very striking difference is the portion of the use of ratios in the construction of thought.One such debate is the difference of opinion regarding the contribution of Ibn Miskawaih in ethical discourse. Some Muslim thinkers say that Ibn Miskawaih is an ethical figure with his main work Tahdzib al-Akhlaq, while other opinions say that he is a moral figure. Thus, this research will show Ibn Miskawaih’s thought building in deeper, so that the foundations of his thought can be seen. More broadly, this research is important to be done to clarify the realm of moral and ethical discourse that develops in Islamic Philosophy, even though Western Philosophy and Islamic Philosophy have the same universal values.This study examines the book Tahdzib al-Akhlaq which is a Ibn Miskawaih master piece. This research attempts to answer the question whether Tahdzib al- Akhlaq is an ethical or moral book. This was done by examining two works of translation of Tahdzib al-Akhlaq, namely The Refinement of Character written by Constantine K. Zurayk and Towards Moral Perfection written by Helmi Hidayat. This research is focused on tracing the arguments compiled by Ibn Miskawaih and tracking the minds of the figures that influence them.From this research it was concluded that Tahdzib al-Akhlaq was not an ethical work, but a moral work. This affirms the criticism made by Fazlur Rahman that Muslim philosophers have failed to produce logically related ethical systems.
Efficiency and Price Effects of Mergers in European Union's Trade and Manufacturing Sectors
Authors: JELIĆ Ozana NADOVEZA , DRUŽIĆ Marko
Published: June 2020

There are two basic tendencies operating simultaneously in every merger case: i) welfare gains due to efficiency related price reductions and ii) welfare losses associated with rising market power and resulting higher prices for consumers. The question of which will prevail is theoretically ambiguous, and consequently has to be settled empirically. The main objectives of this paper are to explore the effects of mergers on efficiency of consolidated firms, and to study their effects on prices in the trade and manufacturing sectors. To explore the effects of mergers on efficiency and prices we employ both a micro and macro approach by relying on firm-level data in the analysis of efficiency effects and on national-level data in the evaluation of price effects of mergers by using the Difference-in-Difference (DiD) approach on a sample of merger cases regulated by the European Commission (EC) during the 2010-2013 period. The DiD based results show that consolidated firms performed better than their competitors in the second year following the merger. Estimated efficiency gains seem to be led by efficiency growth of merged firms in the manufacturing sector. At the same time, we find evidence that compared to their unaffected counterparts, countries and economic activities in which the consolidation took place experienced a higher associated inflation in the year of the merger. Therefore, our results suggest that price effects unfold in the year when the merger is realized while efficiency effects occur with a delay of two years.
Analysis of the State Ownership Realization Process on the Example of Kazakhstan
Authors: CHEREYEVA Bakhytgul Tulegenovna , MALYARENKO Olga Ivanovna , ABAYEVA Gulder Ivanovna , MAYER Olga Iosifovna , OSTRYANINA Tatyana Kenzhebekovna
Published: June 2020

The research sets out the theoretical and methodological foundations of state property management. The use of privatization as the main tool for managing the public sector of the economy is shown, as a proof of which, a review of studies on reforming the economies of various countries is carried out, the main methodology and the results are shown. The authors chose a dynamically developing country of the post-socialist space as an object of research, where an unsuccessful attempt to reform the public sector has already been made, and today, the second one is being conducted. The study uses statistical data from 1991-2004 and 2014-2018, in the context of two periods of privatization of Kazakhstan. The authors give preliminary results of the current reform of the privatization of property and give alternative ways to reduce the public sector of the economy. It is concluded that the problem of quantitative and qualitative growth of the public sector can be solved not only through privatization, but also by maintaining restrictions and requirements on state-owned companies. In the end, this will lead to the promotion of healthy competition; improving the investment climate; increasing business activity and labor productivity, which is so necessary for countries with developing economies.
Validation Data of Mexico's Trade Balance
Authors: PRATS Germán MARTÍNEZ , ARMENTA-RAMÍREZ Aida Beatriz
Published: June 2020

The collection, compilation and dissemination of international merchandise trade statistics must follow standards for international comparability. These processes are structured according to particular institutional arrangements in countries. The general responsibility and dissemination of the Merchandise Trade Balance in Mexico are Tax Administration Service, Ministry of the Economy, Banco de México and the National Institute of Statistics and Geography. At most points of entry, goods are brought into or withdrawn from the customs territory of a country under various customs procedures. The objective of this paper is to establish a method of validation of imports and exports considering the volumes by tariff fraction and unit of measure, as well as the incoterms, to generate a specific registry that allows obtaining more reliable information and serves to make decisions of the actors involved in foreign trade. This information will be used to analyze the evolution and structure of the Commercial Balance of Mexico, as well as to evaluate the interaction that is registered between the commercial activity and the behavior of the national economy, that is why the analysis of the information it generates the commercial balance of Mexico, since this is basic for the decision making of those in charge of public policies in commercial and financial matters.
Fatigue Assessment of 17-4 PH Stainless Steel Notched Specimens Made by Direct Metal Laser Sintering
Authors: Berto Filippo , Fatemi Ali , Shamsaei Nima , Razavi Seyed Mohammad Javad
Published: June 2020

Direct metal laser sintering (DMLS) offers economical production of customized components with complex geometries in a shorter design-to-manufacture cycle. Similar to other additive manufacturing (AM) techniques, this method is used for the production of complex geometries that include various kinds of notch geometries. The basic understanding of the fatigue behavior of the notched specimens produced with AM techniques, however, must be substantially improved before the unique features of this rapidly developing technology can be used in critical load bearing applications. The axial and torsional fatigue behavior of severely notched components made of additively manufactured 17-4 PH stainless steel was studied in the present paper. The experimental fatigue tests were performed under axial- and torsional-loading conditions. Cylindrical specimens with notch tip radius of 0.1 mm were employed to evaluate the fatigue behavior of the specimens under different loading conditions.
An Efficient Test Method for the Quantification of Technology-Dependent Factors Affecting the Fatigue Behavior of Metallic Additive Manufacturing Components
Authors: Nicoletto Gianni
Published: June 2020

Powder bed fusion (PBF) is the most widely used additive manufacturing (AM) technology for producing high-performance metal parts. The fatigue characterization of PBF metals is a fundamental step toward technology acceptance for structural applications. Most published fatigue characterizations have adopted standard specimens with machined gage sections, although, to be competitive with conventional technologies, machining of PBF parts should be minimized. Therefore, the impact of the as-built surface quality on the fatigue performance of PBF parts is a major concern for part design and qualification.

We describe a novel testing approach that adopts miniature specimens and plane cyclic bending for the fatigue characterization of as-built PBF metals and assess this approach for the case of a Ti6Al4V alloy against data obtained with standard specimen geometries and test methods. The role of factors such as stress versus build directionality, geometrical notches, and PBF technology on the high-cycle fatigue of Ti6Al4V is then quantified. The proposed method is cost-effective and has flexible applicability. Therefore, it is useful for basic fatigue research of PBF metals and for supporting the qualification of fatigue-critical PBF parts.
NASA's Efforts for the Development of Standards for Additive Manufactured Components
Authors: Russell Richard
Published: June 2020

The current version of NASA standards for manned spaceflight hardware does not contain sufficient detail for the certification of additively manufactured components. The development of additive manufactured standards is currently in work by several standards organizations. NASA, however, cannot wait on these organizations to develop such standards. NASA and its program partners in manned spaceflight (i.e., Commercial Crew, Space Launch System, and the Orion Multi-Purpose Crew Vehicle) are actively developing additively manufactured components for flight as early as 2019. NASA has formed a team to explore the creation of an agency specification for additive manufactured (AM) components. This team includes representatives from nine NASA centers along with representatives from the Federal Aviation Administration, Air Force, and Army. The team concluded that the best way forward would be to create three standards. One each for crewed space flight, non-crewed space flight, and aeronautics. Each standard will be based on the principles of recently released Marshall Space Flight Center (MSFC) Technical Standard MSFC-STD-3716, Standard for Additively Manufactured Spaceflight Hardware by Laser Powder Bed Fusion in Metals. The team agreed that the standard would be written for mature AM technologies and agreed on which families of materials would and would not be applicable. The team developed the structure of the standards and associated standards and created a three-tiered classification system. A matrix was developed that will aid in the creation of tailoring strategies for the various classifications and applications.
Primary Processing Parameter Effects on Defects and Fatigue in Alloy 718
Authors: Sheridan Luke , Whip Bo , Gockel Joy
Published: June 2020

To guarantee the quality of additively manufactured parts, the processing-structure-property-performance (PSPP) relationship must be understood. Despite the current applications of additive manufacturing (AM) in various industries, a suitable understanding of material performance under fatigue loading conditions is lacking. Fatigue performance is largely driven by defects in the material, such as porosity and surface roughness. AM process optimization often is completed through trial-and-error iterations misguided by average values to characterize defects that do not capture the fatigue-limiting behavior. This work investigated the PSPP relationship for a range of AM processing parameters, resulting in variations in porosity and surface roughness for alloy 718 fabricated in the laser powder bed fusion AM process. Nondestructive and destructive characterization methods are used to determine the relationships between varied bulk and contour parameters to porosity and surface roughness characteristics. Porosity coupons with varied bulk parameters were built in the vertical orientation and the internal porosity size and shape metrics were measured using computed tomography. Fatigue testing on machined bars at the nominal parameter set was performed to determine the baseline performance of the AM material. Fatigue bars with as-built surfaces and varied contour parameters were built in the vertical orientation to determine the relationship between surface roughness and fatigue life. The surfaces were characterized before testing using areal surface metrology to determine the relationship of processing parameters to the standard height-based measurement methods. By using these methods, the determined PSPP relationships for porosity and surface roughness can be used to guide process optimization and to inform the qualification strategy for AM components.
Expression of Additive Manufacturing Surface Irregularities through a Flaw-Based Assessment
Authors: Gumpinger Johannes , Brandão Ana D. , Beevers Emilie , Rohr Thomas , Ghidini Tommaso , Beretta Stefano , Romano Simone
Published: June 2020

Metal additive manufacturing (AM) has progressed from a pure research topic to an indispensable manufacturing process for many industries within the past 15 years. For the space industry, the performance of a variety of products, including structures, antennas, propulsion parts, and optical equipment is being improved through this manufacturing technique. Process-inherent defects are still encountered and may lead to significant safety factors, particularly for highly loaded, mission-critical applications. An analysis of the fatigue properties of AlSi10Mg produced by selective laser melting (SLM) has shown that the fatigue strength and fatigue life of machined specimens could be accurately predicted by adopting a defect-tolerant design concept. In details, the fatigue strength appeared to be controlled by the defect with the maximum stress intensity factor (SIF) present in each specimen. The fatigue properties could be predicted by treating the lack-of-fusion defects as short cracks. For near-net-shaped (i.e., not machined) surfaces, a previous investigation studied the influence of building direction, platform temperature, powder layer thickness, surface finish, and heat treatment on fatigue properties of AM AlSi10Mg and X-ray computed tomography (XCT) was performed to research the defect population. The work showed that processing parameters and surface treatment influenced fatigue properties, as expected for conventionally produced material. This study conducted an accurate analysis of the subsurface features at the fracture origin of AlSi10Mg specimens, manufactured by SLM and treated with different surface finish. On the basis of these results, a simple fracture mechanics assessment inside the Kitagawa diagram is proposed, which relies on the size of critical defects and the residual stress obtained on the surface. The applicability of this approach to define the quality of AM material in the near-net-shaped condition is discussed.
Additive Manufactured Polymer Test Coupons: Issues and Solutions
Authors: Andrulonis Rachael , Lovingfoss Royal , Tomblin John
Published: June 2020

Leveraging the experience and lessons learned from the National Center for Advanced Material Performance (NCAMP) and the Composite Materials Handbook–17 (CMH-17) composite material databases, a new qualification program for polymer materials for additive manufacturing (AM) has been developed utilizing several existing ASTM test methods. Many of the test methods required for the standardized mechanical testing necessary for qualification, however, are not directly applicable to additive manufactured materials and require guidance or modifications. As part of this research effort, the applicability of several existing mechanical test methods to polymer AM materials has been evaluated. Modifications were necessary for certain methods, including compression, open-hole compression, and filled-hole compression. The necessary modifications presented here also will be documented in publicly available reports with statistically reduced data, including B-basis allowables. Although this program focused on an extrusion-based material and process, much of the results have broad applicability to other polymer AM materials and processes. An overview of the test program, issues, and possible solutions to deliver useful results to the aviation industry are presented.
NDE-Based Quality Assurance of Metal Additively Manufactured Aerospace Parts at NASA, JAXA, and ESA
Authors: Waller Jess M. , Burke Eric R. , Wells Douglas N. , Nichols Charles T. , Brandão Ana D. , Gumpinger Johannes , Born Martin , Ghidini Tommaso , Nakagawa Tsuyoshi , Koike Akio , Mitsui Masami , Itoh Tsuyoshi
Published: June 2020

As metal additive manufactured spaceflight hardware moves closer to use in upcoming missions, the need for appropriate nondestructive evaluation (NDE) procedures to qualify and certify parts becomes more pressing. Traditionally, the level and specificity of certification requirements for aerospace parts is linked to part criticality, which is determined by structural margin, consequence of failure, and part inspectability. Unfortunately, rule-level (performance-based) certification requirements often do not define specific or acceptable NDE procedures or requirements. This level of detail usually falls on the original equipment manufacturer (OEM), which is unwise in the case of new technology, such as additive manufacturing (AM). Instead, it is incumbent upon the end user to communicate risks and with the OEM and to provide oversight to ensure risks are controlled. These risks arise from many sources, including uncertainty about property optimization for rapidly evolving AM processes, lack of engineering experience, and limited operational histories. From the NDE perspective, the main risk arises from uncertainty in the NDE procedure to detect the requisite critical flaw type, size, and distribution. Because the level of criticality of AM aerospace parts is expected to increase, more effort is needed to characterize and understand fatigue and fracture properties of AM materials. Crack initiation resulting from the presence of AM flaws must be considered. This requires knowledge of the critical initial flaw size (CIFS) and the appropriateness of NASA-STD-5009 flaw sizes. Knowledge of the CIFS for a given AM flaw type will allow for the fracture control and NDE communities to evaluate risks and communicate recommendations regarding the acceptability of risk. Toward this goal, this paper discusses NDE-related activities at the National Aeronautics and Space Administration, Japan Space Exploration Agency, and European Space Agency. Current NDE best practices for AM hardware are discussed, along with tailoring NDE according to part criticality.
Development and Testing of 316L Stainless Steel Metal Additive Manufacturing Test Articles for Powder Bed Fusion and Directed Energy Deposition Processes
Authors: Coughlin Jessica L. , Hicks Trevor G. , Dougherty Patrick S. , Attanasio Steven A.
Published: June 2020

The advancement of metal additive manufacturing (AM) technologies provides opportunities for novel part design and improved manufacturing capability compared with parts fabricated using wrought or cast materials. Heterogeneous microstructures and anisotropic material properties complicate the application of this technology to critical components. In this study, metal AM test article builds were designed for powder bed fusion (PBF) and directed energy deposition (DED) processes. The PBF test article build was designed to evaluate the effects of specimen orientation, thickness, surface condition, and build volume location on tensile properties. This build design was tested using the laser (L)-PBF process with 316L stainless steel. The L-PBF builds involved the fabrication of as-built tension test specimen geometries with variations in thickness and orientation to accurately represent the surface finish and microstructure that exist in parts with features of these sizes and orientations. Variability in tensile properties for the L-PBF test article builds were correlated with specimen orientation and thickness; differences in surface condition were correlated with tensile property variability in thin specimens but not in thicker specimens. The DED test article build was designed to evaluate the effects of specimen orientation and build feature thermal history and was tested using the electron beam (EB)-DED process with 316L stainless steel. Some tensile property variability related to build feature type was identified in the EB-DED builds, but other phenomena in the builds affected variability, including incomplete fusion defects and the formation of a detrimental, secondary sigma phase. The results demonstrated the need for a thorough evaluation and understanding of the numerous factors that affect the properties of metal AM parts. The build design concepts tested can demonstrate the effects of such factors on metal AM mechanical properties and provide a framework for a qualification schema that accounts for potential sources of variability affecting AM material performance.
Nondestructive Evaluation of Additive Manufactured Parts Using Process Compensated Resonance Testing
Authors: Livings Richard A. , Biedermann Eric J. , Wang Chen , Chung Thomas , James Steven , Waller Jess M. , Volk Scott , Krishnan Ajay , Collins Shane
Published: June 2020

Variations in build process parameters, post-processing parameters, and feedstock have a significant impact on the structural integrity and performance of components made with additive manufacturing (AM). Effective nondestructive testing (NDT) is critical for ensuring the structural integrity of components. Complex geometries, nonequilibrium microstructures, new process variables, and lack of clear accept or reject criteria for AM components present new challenges to NDT. Quantitative, volumetric NDT methods that can detect material defects of interest in complex geometries are required. Process compensated resonance testing (PCRT) is an NDT method that uses a swept sine input to excite the component's resonance modes of vibration. The resonance frequencies are recorded, analyzed statistically, and compared to acceptability limits established using a database of training components. The swept sine input excites whole-body vibrational modes in nearly any geometry, and the component's resonance frequencies correlate directly to its structural integrity. In this study, PCRT evaluations were performed on titanium alloy (Ti-6Al-4V) populations made with electron beam PBF and aluminum alloy (AlSi10Mg) populations made with laser PBF. The evaluations were conducted in support of ASTM round-robin testing. In the Ti-6Al-4V population, PCRT showed clear resonance frequency differences between nominal specimens and off-nominal specimens with defective material states. PCRT also quantified the effects of hot isostatic pressing (HIP). PCRT pass/fail NDT of the Ti-6Al-4V population in the pre-HIP and post-HIP states demonstrated 100% accuracy. Computed tomography scans of the post-HIP specimens showed no clear indications of porosity. Follow-up tensile testing of a subset of nominal and off-nominal specimens in the post-HIP state showed that the off-nominal specimens had lower yield stresses and ultimate tensile stresses than nominal specimens. In the AlSi10Mg population, PCRT detected differences between recycled and virgin feedstock powder. PCRT pass/fail NDT of AlSi10Mg specimens exposed to nominal and off-nominal heat treatment demonstrated 100% accuracy.
Fatigue and Fracture Behavior of Additively Manufactured Austenitic Stainless Steel
Authors: Marchi Chris San , Smith Thale R. , Sugar Joshua D. , Balch Dorian K.
Published: June 2020

Additive manufacturing (AM) includes a diverse suite of innovative manufacturing processes for producing near-net shape components, typically from powder or wire feedstock. Reported mechanical properties of AM materials vary significantly depending on the details of the manufacturing process and the characteristics of the processing defects (namely, lack of fusion defects). However, an excellent combination of strength, ductility, and fracture resistance can be achieved in AM-type 304L and 316L austenitic stainless steels by minimizing processing defects. It is important to recognize that localized solidification processing during AM produces microstructures more analogous to weld microstructures than wrought microstructures. Consequently, the mechanical behavior of AM austenitic stainless steels in harsh environments can diverge from the performance of wrought materials. This report provides an overview of the fracture and fatigue response of type 304L materials from both directed energy deposition and powder bed fusion techniques. In particular, the mechanical performance of these materials is considered for high-pressure hydrogen applications by evaluating fatigue and fracture resistance after thermally precharging test specimens in high-pressure gaseous hydrogen. The mechanical behaviors are considered with respect to previous reports on hydrogen-assisted fracture of austenitic stainless steel welds and the unique characteristics of the AM microstructures. Fatigue crack growth can be relatively insensitive to processing defects, displaying similar behavior as wrought materials. In contrast, fracture resistance of dense AM austenitic stainless steel is more consistent with weld metal than with compositionally similar wrought materials. Hydrogen effects in the AM materials generally are more severe than in wrought materials but are comparable to measurements on welded austenitic stainless steels in hydrogen environments. Although hydrogen-assisted fracture manifests differently in welded and AM austenitic stainless steel, the fracture process appears to have a common origin in the compositional microsegregation intrinsic to solidification processes.
Eddy Current Technologies for Real-Time Monitoring and Post-Process Examination of Laser Powder Bed Fusion Process
Authors: Todorov Evgueni Iordanov
Published: June 2020

Complex geometry, variable macrostructure, anisotropy, distributed defects, surface roughness, and residual stresses of additively manufactured (AM) components challenge nondestructive evaluation processes developed and validated for conventional manufacturing. Electromagnetic and eddy current (EC) technologies were identified as promising for in-process, real-time monitoring, and post-process examination of AM components. Powder and solid specimens were prepared for electromagnetic property measurements and technique development and optimization. The post-process specimens were fabricated with roughness representative of surface conditions during fabrication inside the AM machine. Artificial and natural discontinuities were fabricated with the electrical discharge machining process and by varying the laser fusion parameters. Extensive computed modeling was conducted to develop an optimized array EC (AEC) sensor and technique for AM real-time monitoring. The AEC sensor could withstand temperatures up to 100ºC. Computational modeling was conducted to investigate the likelihood of metal powder disturbance by the EC sensor electromagnetic field. A real-time data acquisition system was assembled and integrated with an open-architecture laser powder bed fusion (L-PBF) test bed. The EC system performance for real-time monitoring of the L-PBF process was demonstrated through layer-by-layer testing of Inconel 625 coupons, with AM built discontinuities and lack of fusion. The L-PBF process was representative of a typical AM process used for super alloys and steels with preheat of substrate plate and AM test specimens to 100ºC. Existing AEC equipment and techniques were used for post-process examination of AM solid specimens at room temperatures. The AEC technology demonstrated excellent sensitivity to seeded and natural surface and near-surface subsurface discontinuities and surface topography during real-time monitoring and post-processing. Electromagnetic and EC techniques were demonstrated to examine powder before fabrication. The application of modeling tools reduced developmental time and improved efficiency. Further research and development was recommended to improve data acquisition process and transition AEC monitoring technology to other AM processes.
Effects of the Shielding Argon Gas Flow on the Mechanical and Physical Properties of Selective Laser Melted Ti-6Al-4V Solid Material
Authors: Quintana Oscar A. , Hightower Nia , Rybolt Robert
Published: June 2020

Selective laser melting (SLM) is an additive manufacturing (AM) technology proven to produce near fully dense components made of a wide number of materials and with the required printing resolution to manufacture structures with microscopic structural details. Because of complexity of the processing and tensile and fatigue relationships, SLM requires more investigation. For instance, the shielding gas flow (argon flow) has affected the stability of the process and consequently the quality of AM components. In addition to provide an inert atmosphere during the printing process, the argon flow removes process byproducts, such as spatter and smoke that occur during the SLM. Inefficient argon flow results in the interaction of the laser beam with the by-products, leading to the redeposition of these onto the melt pool. This has a negative impact on the surface morphology, density of the parts, and ultimately mechanical performance. In this study we investigated two argon flows (optimized vs. nonoptimized) and their effects on the tensile properties and surface finish of Ti-6Al-4V samples (stress relieved) with different size dimensions and printing directions (horizontal vs. vertical). For the nonoptimized argon flow, we found tensile properties that ranged from 826 to 1,052 MPa ultimate tensile strength (UTS), 925 to 966 MPa yield strength (YS), and 0.6–17% elongation (Elong.). The optimized flow exhibited more consistent results, as follows: 998–1,039 MPa UTS, 878–940 MPa YS, and 15–17% Elong. No statistical difference was found on the average surface roughness for samples printed in the vertical direction (7.26 μm Ra, and 47.90 μm Rz), regardless of the argon flow used. For the horizontal direction, however, the optimized flow showed a smoother surface finish (6.48 μm Ra, 39.46 μm Rz) compared with the nonoptimized flow (11.72 μm Ra, 71.13 μm Rz). The effects of argon flow on density and metallurgical characteristics of printed parts also were discussed.
Rapid Additive Qualification Using Probabilistics (RAQUP)
Authors: Khan Genghis , Kumar Natarajan Chennimalai , Wang Liping , Gupta Vipul , Dheeradhada Voramon , Hanlon Tim , Dial Laura , Vinciquerra Joseph
Published: June 2020

Assurance of structural integrity of additively manufactured parts requires the qualification of materials, processes and machines. For the original equipment manufacturer (OEM), the speed and cost of qualification is critical for competitive advantage. During the past two decades, GE Global Research has developed and advanced the state-of-the-art of a suite of primarily Bayesian probabilistic methods and tools that have been leveraged on a wide variety of aviation, power, oil and gas and other applications for performance, cost, quality and reliability. Recently we have been applying them to additive manufacturing related qualifications. This work provides an overview of these probabilistic methods and tools and shows an application that reduces cycle time by four to five times in the development of additive alloy families.
Characterization of Stress Fields Near Pores and Application to Fatigue Lives
Authors: Sobotka James C. , McClung R. Craig
Published: June 2020

Additive manufacturing (AM) is a novel fabrication process with the potential to create unique parts beyond the capabilities of conventional manufacturing methods. However, because the AM process produces both the part and the material simultaneously, certification of safety-critical structural metallic parts requires new approaches that more explicitly quantify the influence of the AM process on the quality of the part. For example, the AM process can, when not properly designed and controlled, create defects, such as porosity, lack of fusion, or severe surface roughness. If these defects occur in a region of significant cyclic stress, they can promote the nucleation of cracks that, in turn, can grow to cause fracture of the part. This paper summarizes recent investigations into analytical characterization of defects and their effect on the structural integrity of additive manufactured parts. Specifically, this work documents predictive mechanics models that characterize the effects of pores on fatigue crack formation. These results provide insight into the effects of pore size and shape on fatigue lives under uniaxial tension.
Popular Perceptions of Democracy in China
Authors: Zhai Yida
Published: June 2020

Democracy is a contested concept; this article empirically examines how Chinese people understand the concept of democracy in practice when they use this term. Using four rounds of national survey data, we seek to clarify the characteristics of the Chinese people’s perception of democracy and its longitudinal changes during the past few decades. The results show an increase in the percentage of people who view democracy procedurally. The popular perception of democracy does matter. People who view democracy substantively tend to see democracy as less suitable for China, and to overrate the democratic level of the current regime, compared to those who view democracy procedurally. No matter how people perceive it, satisfaction with democracy has declined over the past decade. The demographic analysis shows that Chinese youth adhere to a procedural concept of democracy more than a substantive one, which has important implications for China’s future political development.