scholarly journals Mechanical Recyclability of Polypropylene Composites Produced by Material Extrusion-Based Additive Manufacturing

Polymers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1318 ◽  
Author(s):  
Martin Spoerk ◽  
Florian Arbeiter ◽  
Ivan Raguž ◽  
Clemens Holzer ◽  
Joamin Gonzalez-Gutierrez
Keyword(s):  
Additive Manufacturing ◽  
Chain Scission ◽  
Fused Filament Fabrication ◽  
Polypropylene Composites ◽  
Material Extrusion ◽  
Wide Range ◽  
Tremendous Amount ◽  
3D Printed ◽  
The Impact

Due to a lack of long-term experience with burgeoning material extrusion-based additive manufacturing technology, also known as fused filament fabrication (FFF), considerable amounts of expensive material will continue to be wasted until a defect-free 3D-printed component can be finalized. In order to lead this advanced manufacturing technique toward cleaner production and to save costs, this study addresses the ability to remanufacture a wide range of commercially available filaments. Most of them either tend to degrade by chain scission or crosslinking. Only polypropylene (PP)-based filaments appear to be particularly thermally stable and therefore suitable for multiple remanufacturing sequences. As the extrusion step exerts the largest influence on the material in terms of temperature and shear load, this study focused on the morphological, rheological, thermal, processing, tensile, and impact properties of a promising PP composite in the course of multiple consecutive extrusions as well as the impact of additional heat stabilizers. Even after 15 consecutive filament extrusions, the stabilized additively manufactured PP composite revealed an unaltered morphology and therefore the same tensile and impact strength as the initial material. As the viscosity of the material of the 15th extrusion was nearly identical to that of the 1st extrusion sequence, the processability both in terms of extrusion and FFF was outstanding, despite the tremendous amount of shear and thermal stress that was undergone. The present work provides key insights into one possible step toward more sustainable production through FFF.

scholarly journals Towards Distributed Recycling with Additive Manufacturing of PET Flake Feedstocks

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4273
Author(s):  
Helen A. Little ◽  
Nagendra G. Tanikella ◽  
Matthew J. Reich ◽  
Matthew J. Fiedler ◽  
Samantha L. Snabes ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
3D Printing ◽  
Thermal Characterization ◽  
3D Print ◽  
Wide Range ◽  
3D Printed ◽  
Sequential Combination ◽  
Future Work ◽  
The Impact ◽  
First Time

This study explores the potential to reach a circular economy for post-consumer Recycled Polyethylene Terephthalate (rPET) packaging and bottles by using it as a Distributed Recycling for Additive Manufacturing (DRAM) feedstock. Specifically, for the first time, rPET water bottle flake is processed using only an open source toolchain with Fused Particle Fabrication (FPF) or Fused Granular Fabrication (FGF) processing rather than first converting it to filament. In this study, first the impact of granulation, sifting, and heating (and their sequential combination) is quantified on the shape and size distribution of the rPET flakes. Then 3D printing tests were performed on the rPET flake with two different feed systems: an external feeder and feed tube augmented with a motorized auger screw, and an extruder-mounted hopper that enables direct 3D printing. Two Gigabot X machines were used, each with the different feed systems, and one without and the latter with extended part cooling. 3D print settings were optimized based on thermal characterization, and both systems were shown to 3D print rPET directly from shredded water bottles. Mechanical testing showed the importance of isolating rPET from moisture and that geometry was important for uniform extrusion. The mechanical strength of 3D-printed parts with FPF and inconsistent flow is lower than optimized fused filament, but adequate for a wide range of applications. Future work is needed to improve consistency and enable water bottles to be used as a widespread DRAM feedstock.

Fused Filament Fabrication 3D Printed Polylactic Acid Electroosmotic Pumps

Lab on a Chip ◽  
2021 ◽  
Author(s):  
Liang Wu ◽  
Stephen Beirne ◽  
Joan-Marc Cabot Canyelles ◽  
Brett Paull ◽  
Gordon G. Wallace ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
3D Printing ◽  
Polylactic Acid ◽  
Fused Filament Fabrication ◽  
Flexible Approach ◽  
Electroosmotic Pump ◽  
3D Printed ◽  
Electroosmotic Pumps

Additive manufacturing (3D printing) offers a flexible approach for the production of bespoke microfluidic structures such as the electroosmotic pump. Here a readily accessible fused filament fabrication (FFF) 3D printing...

scholarly journals Impact of Diagnosed and Undiagnosed Respiratory Pseudomonas on VAP and VAE During Long-Term Acute Care

2020 ◽  
Vol 41 (S1) ◽  
pp. s258-s259
Author(s):  
James Harrigan ◽  
Ebbing Lautenbach ◽  
Emily Reesey ◽  
Magda Wernovsky ◽  
Pam Tolomeo ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Acute Care ◽  
Statistical Significance ◽  
Rrna Gene ◽  
Care Hospital ◽  
16S Sequencing ◽  
Increased Risk ◽  
Wide Range ◽  
The Impact

Background: Clinically diagnosed ventilator-associated pneumonia (VAP) is common in the long-term acute-care hospital (LTACH) setting and may contribute to adverse ventilator-associated events (VAEs). Pseudomonas aeruginosa is a common causative organism of VAP. We evaluated the impact of respiratory P. aeruginosa colonization and bacterial community dominance, both diagnosed and undiagnosed, on subsequent P. aeruginosa VAP and VAE events during long-term acute care. Methods: We enrolled 83 patients on LTACH admission for ventilator weaning, performed longitudinal sampling of endotracheal aspirates followed by 16S rRNA gene sequencing (Illumina HiSeq), and bacterial community profiling (QIIME2). Statistical analysis was performed with R and Stan; mixed-effects models were fit to relate the abundance of respiratory Psa on admission to clinically diagnosed VAP and VAE events. Results: Of the 83 patients included, 12 were diagnosed with P. aeruginosa pneumonia during the 14 days prior to LTACH admission (known P. aeruginosa), and 22 additional patients received anti–P. aeruginosa antibiotics within 48 hours of admission (suspected P. aeruginosa); 49 patients had no known or suspected P. aeruginosa (unknown P. aeruginosa). Among the known P. aeruginosa group, all 12 patients had P. aeruginosa detectable by 16S sequencing, with elevated admission P. aeruginosa proportional abundance (median, 0.97; IQR, 0.33–1). Among the suspected P. aeruginosa group, all 22 patients had P. aeruginosa detectable by 16S sequencing, with a wide range of admission P. aeruginosa proportional abundance (median, 0.0088; IQR, 0.00012–0.31). Of the 49 patients in the unknown group, 47 also had detectable respiratory Psa, and many had high P. aeruginosa proportional abundance at admission (median, 0.014; IQR, 0.00025–0.52). Incident P. aeruginosa VAP was observed within 30 days in 4 of the known P. aeruginosa patients (33.3%), 5 of the suspected P. aeruginosa patients (22.7%), and 8 of the unknown P. aeruginosa patients (16.3%). VAE was observed within 30 days in 1 of the known P. aeruginosa patients (8.3%), 2 of the suspected P. aeruginosa patients (9.1%), and 1 of the unknown P. aeruginosa patients (2%). Admission P. aeruginosa abundance was positively associated with VAP and VAE risk in all groups, but the association only achieved statistical significance in the unknown group (type S error <0.002 for 30-day VAP and <0.011 for 30-day VAE). Conclusions: We identified a high prevalence of unrecognized respiratory P. aeruginosa colonization among patients admitted to LTACH for weaning from mechanical ventilation. The admission P. aeruginosa proportional abundance was strongly associated with increased risk of incident P. aeruginosa VAP among these patients.Funding: NoneDisclosures: None

scholarly journals Modeling Building Stock Development

2021 ◽  
Vol 13 (2) ◽  
pp. 723
Author(s):  
Antti Kurvinen ◽  
Arto Saari ◽  
Juhani Heljo ◽  
Eero Nippala
Keyword(s):  
Model Development ◽  
Housing Demand ◽  
Quality Data ◽  
Building Stock ◽  
Test Arena ◽  
Climate Targets ◽  
Wide Range ◽  
Key Variables ◽  
The Impact

It is widely agreed that dynamics of building stocks are relatively poorly known even if it is recognized to be an important research topic. Better understanding of building stock dynamics and future development is crucial, e.g., for sustainable management of the built environment as various analyses require long-term projections of building stock development. Recognizing the uncertainty in relation to long-term modeling, we propose a transparent calculation-based QuantiSTOCK model for modeling building stock development. Our approach not only provides a tangible tool for understanding development when selected assumptions are valid but also, most importantly, allows for studying the sensitivity of results to alternative developments of the key variables. Therefore, this relatively simple modeling approach provides fruitful grounds for understanding the impact of different key variables, which is needed to facilitate meaningful debate on different housing, land use, and environment-related policies. The QuantiSTOCK model may be extended in numerous ways and lays the groundwork for modeling the future developments of building stocks. The presented model may be used in a wide range of analyses ranging from assessing housing demand at the regional level to providing input for defining sustainable pathways towards climate targets. Due to the availability of high-quality data, the Finnish building stock provided a great test arena for the model development.

scholarly journals Strength Comparison of FDM 3D Printed PLA Made by Different Manufacturers

TEM Journal ◽  
2020 ◽  
pp. 966-970
Author(s):  
Damir Hodžić ◽  
Adi Pandžić ◽  
Ismar Hajro ◽  
Petar Tasić
Keyword(s):  
Experimental Study ◽  
Additive Manufacturing ◽  
Fused Deposition Modelling ◽  
Fused Deposition ◽  
Manufacturing Technique ◽  
Plastic Materials ◽  
Wide Range ◽  
3D Printed ◽  
The Difference ◽  
Printing Parameters

Widely used additive manufacturing technique for plastic materials is Fused Deposition Modelling (FDM). The FDM technology has gained interest in industry for a wide range of applications, especially today when large number of different materials on the market are available. There are many different manufacturers for the same FDM material where the difference in price goes up to 50%. This experimental study investigates possible difference in strength of the 3D printed PLA material of five different manufacturers. All specimens are 3D printed on Ultimaker S5 printer with the same printing parameters, and they are all the same colour.

scholarly journals Congenital Micropenis: Aetiology And Management

2021 ◽  
Author(s):  
Marianna Rita Stancampiano ◽  
Kentaro Suzuki ◽  
Stuart O’Toole ◽  
Gianni Russo ◽  
Gen Yamada ◽  
...  
Keyword(s):  
Racial Differences ◽  
Small Sample Size ◽  
Small Sample ◽  
Long Term Outcomes ◽  
Penile Length ◽  
Appearance Quality ◽  
Wide Range ◽  
The Impact

Abstract In the newborn, penile length is determined by a number of androgen dependent and independent factors. The current literature suggests that there are inter-racial differences in stretched penile length in the newborn and although congenital micropenis should be defined as a stretched penile length of less than 2.5SDS of the mean for the corresponding population and gestation, a pragmatic approach would be to evaluate all boys with a stretched penile length below 2 cm, as congenital micropenis can be a marker for a wide range of endocrine conditions. However, it remains unclear as to whether the state of micropenis, itself, is associated with any long-term consequences. There is a lack of systematic studies comparing the impact of different therapeutic options on long-term outcomes, in terms of genital appearance, quality of life and sexual satisfaction. To date, research has been hampered by a small sample size and inclusion of a wide range of heterogeneous diagnoses; for these reasons, condition specific outcomes have been difficult to compare between studies. Lastly, there is a need for a greater collaborative effort in collecting standardized data so that all real-world or experimental interventions performed at an early age can be studied systematically into adulthood.

Material Flow Rate Estimation in Material Extrusion Additive Manufacturing

2021 ◽  
Vol 13 (1) ◽  
pp. 46-56
Author(s):  
G.P. Greeff
Keyword(s):  
Additive Manufacturing ◽  
Flow Rate ◽  
Material Flow ◽  
Fused Deposition Modeling ◽  
Volumetric Flow Rate ◽  
Cost Effective ◽  
Fused Filament Fabrication ◽  
Material Extrusion ◽  
Fused Deposition ◽  
G Code

The additive manufacturing of products promises exciting possibilities. Measurement methodologies, which measure an in-process dataset of these products and interpret the results, are essential. However, before developing such a level of quality assurance several in-process measurands must be realized. One of these is the material flow rate, or rate of adding material during the additive manufacturing process. Yet, measuring this rate directly in material extrusion additive manufacturing presents challenges. This work presents two indirect methods to estimate the volumetric flow rate at the liquefier exit in material extrusion, specifically in Fused Deposition Modeling or Fused Filament Fabrication. The methods are cost effective and may be applied in future sensor integration. The first method is an optical filament feed rate and width measurement and the second is based on the liquefier pressure. Both are used to indirectly estimate the volumetric flow rate. The work also includes a description of linking the G-code command to the final print result, which may be used to create a per extrusion command model of the part.

scholarly journals Arts-Based Interventions for Professionals in Caring Roles During and After Crisis: A Systematic Review of the Literature

2020 ◽  
Vol 11 ◽  
Author(s):  
Dominik Havsteen-Franklin ◽  
Megan Tjasink ◽  
Jacqueline Winter Kottler ◽  
Claire Grant ◽  
Veena Kumari
Keyword(s):  
Systematic Review ◽  
Future Research ◽  
Safe Place ◽  
Practice Elements ◽  
Qualitative Approaches ◽  
The Arts ◽  
Crisis Events ◽  
Wide Range ◽  
The Impact

Crisis events, such as the COVID-19 pandemic, can have a devastating effect on communities and the care professionals within them. Over recent years, arts-based interventions have helped in a wide range of crisis situations, being recommended to support the workforce during and after complex crisis but there has been no systematic review of the role of arts-based crisis interventions and whether there are cogent themes regarding practice elements and outcomes. We, therefore, conducted a systematic review to (i) define the arts-based change process used during and after crisis events, and (ii) explore the perceptions of intermediate and long-term mental health benefits of arts-based interventions for professionals in caring roles. Our search yielded six studies (all qualitative). All data were thematically aggregated and meta-synthesized, revealing seven practice elements (a safe place, focusing on strengths and protective factors, developing psychosocial competencies to support peers, emotional expression and processing, identifying and naming the impact of the crisis, using an integrative creative approach, and cultural and organizational sensitivity) applied across all six studies, as well as a range of intermediate and long-term benefits shared common features (adapting, growing, and recovering; using the community as a healing resource; reducing or preventing symptoms of stress or trauma reactions, psychophysiological homeostasis). The ways in which these studies were designed independently from one another and yet used the same practice elements in their crisis interventions indicates that there is comparability about how and why the arts-based practice elements are being used and to what effect. Our findings provide a sound basis and meaningful parameters for future research incorporating quantitative and qualitative approaches to firmly establish the effectiveness of art-based interventions, and how arts can support cultural sensitivity, acceptability and indicated outcomes, particularly those relating to stress and trauma during or following a crisis.

scholarly journals Exploring the Impact of Formal Internships on Biomedical Graduate and Postgraduate Careers: An Interview Study

2019 ◽  
Vol 18 (2) ◽  
pp. ar20 ◽  
Author(s):  
Deepshikha Chatterjee ◽  
J. Kevin Ford ◽  
Julie Rojewski ◽  
Stephanie W. Watts
Keyword(s):  
Graduate Students ◽  
Career Exploration ◽  
Interview Study ◽  
National Institutes Of Health ◽  
Career Management ◽  
Management Skills ◽  
Wide Range ◽  
Self Development ◽  
The Impact

Graduate students and postdocs in science, technology, engineering, and math fields are faced with a wide range of career paths to employment, but they are often not trained to effectively pursue these opportunities. The lack of career management skills implies long tenures in graduate school for many students, especially as tenure-track positions in academia dwindle. At our university, we used a cohort model in which graduate students and postdocs were encouraged to apply to the Broadening Experiences in Scientific Training program (BEST under the aegis of the National Institutes of Health) that provided opportunities to gain career management skills, engage in career exploration, and complete at least one formal internship. In this interview study of the BEST trainees, we investigated the efficacy of internships as career exploration tools and associated outcomes. Our findings show that internships were seen as effective career exploration and self-development vehicles that influenced participants’ long-term career goals. Graduate students and postdocs reported gaining transferable knowledge and skills, in addition to receiving valuable industry mentoring and networking opportunities.

scholarly journals Regional Integration: Do Intra-African Trade and Migration Improve Income in Africa?

2019 ◽  
Vol 43 (6) ◽  
pp. 587-631 ◽  
Author(s):  
Blaise Gnimassoun
Keyword(s):  
Regional Integration ◽  
Capita Income ◽  
Per Capita Income ◽  
Cross Sectional ◽  
Wide Range ◽  
Per Capita ◽  
Migration Flows ◽  
And Migration ◽  
The Impact

Regional integration in Africa is a subject of great interest, but its impact on income has not been studied sufficiently. Using cross-sectional and panel estimations, this article examines the impact of African integration on real per capita income in Africa. Accordingly, we consider intra-African trade and migration flows as quantitative measures reflecting the intensity of regional integration. To address the endogeneity concerns, we use a gravity-based, two-stage least-squares strategy. Our results show that, from a long-term perspective, African integration has not been strong enough to generate a positive, significant, and robust impact on real per capita income in Africa. However, it does appear to be significantly income-enhancing in the short and medium terms but only through intercountry migration. These results are robust to a wide range of specifications.

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