8 research outputs found
Utilization of waste foam concrete with MPCM as a substitution material for cement in mortars
No full textGiven the rising popularity of foam concrete (FC) for both structural and insulating purposes, evaluating the feasibility of recycling after its lifespan is crucial in the context of the growing emphasis on sustainable building practices. One approach to recycling FC incorporating microencapsulated phase change material (MPCM) involves utilizing recycled foam concrete powder (RFCP) as an additive in cement composites. This article aims to investigate the impact of RFCP without and with MPCM when employed as a partial replacement for cement in mortars. Furthermore, the study verifies various processing methods such as crushing, grinding, and heat treatment for RFCP. The results reveal that introducing RFCP, regardless of the MPCM presence and processing method, significantly affects the properties of both cement and mortar. The presence of MPCM in RFCP negatively influences the flowability of fresh mortars, delays the setting time, and reduces the hydration heat within the first 48 h. However, the presence of MPCM does not significantly affect mortars' strength and water absorption but simultaneously it increases shrinkage and decreases thermal conductivity. Grinding RFCP mitigates the adverse effects of MPCM, while thermal processing removes MPCM from RFCP, albeit with an associated increase in water demand. A noteworthy finding is that mortars having 20 % RFCP, with or without MPCM, exhibit compressive strengths exceeding 16 MPa and 42.5 MPa after 2 and 28 days, respectively. These results meet the requirements outlined in EN-196-1 for cement of class 42.5, highlighting the potential to produce CEM II/A-F 42.5 using RFCP with MPCM.Materials- Mechanics- Management & DesignArts & CraftsMaterials and Environmen
Early-stage analysis of a novel insulation material based on MPCM-doped cementitious foam: Modelling of properties, identification of production process hotspots and exploration of performance trade-offs
No full textThis study presents an early-stage design exploration of NRG-Foam, an innovative insulation material composed of cementitious foam doped with microencapsulated phase change materials (MPCMs). The study comprises the static part that utilizes life cycle assessment and life cycle costing assessment for getting insight into the impacts of the NRG-Foam production process and the dynamic part that identifies the trade-offs between performance characteristics of NRG-Foam using multi-objective optimization. The production of MPCMs was found to be a major contributor to environmental impacts while the addition of small amounts of reduced graphene oxide amplifies the impacts even further. The hot spot analysis pinpointed high electricity consumption as the main driver of environmental impacts. A multi-objective optimization analysis revealed trade-offs between performance characteristics, emphasizing the necessity of compromises during material development. The selection of the MPCM type was shown to be determinative of the final properties of NRG-Foam.Materials and Environmen
Mechanical Properties of Lightweight Cementitious Cellular Composites Incorporating Micro-Encapsulated Phase Change Material
No full textThis work focuses on combining digitally architected cellular structures with cementitious mortar incorporating micro-encapsulated phase change material (mPCM) to fabricated lightweight cementitious cellular composites (LCCCs). Voronoi structures with different randomness are designed for the LCCCs. Aided by the indirect 3D printing technique, the LCCCs were prepared with a reference mortar (REF) and a mortar incorporating mPCM. The compressive behavior of the LCCCs was studied at the age of 28 days, by experimental and numerical methods. It was found that the highly randomized Voronoi structure and the mPCM have minor negative influence on the compressive properties of the LCCCs. The mPCM incorporated LCCCs have high relative compressive strength compared to conventional foam concrete. Furthermore, the critical role of air voids defects on the compressive behavior was identified. The highly randomized porous Voronoi structure, high mPCM content and good compressive strength ensure the LCCCs’ great potential as a novel thermal insulation construction material.Materials and Environmen
Progressive coding for hyperspectral signature characterization
No full textSpectral signature coding is an effective means of characterizing spectral features. This paper develops a rather different encoding concept, called progressive signature coding (PSC), which encodes a signature in a hierarchical manner. More specifically, it progressively encodes a spectral signature in multiple stages; each of these stages captures disjoint spectral information contained in the spectral signature. As a result of this progressive coding, a spectral profile of progressive changes in a spectral signature can be generated for spectral characterization. The proposed idea is very simple and evolved from the pulse code modulation (PCM) commonly used in communications and signal processing. It expands PCM to multistage PCM (MPCM) in the sense that a signature can be decomposed and quantized by PCM progressively in multiple stages for spectral characterization. In doing so, the MPCM generates a priority code for a spectral signature so that its spectral information captured in different stages can be prioritized in accordance with significance of changes in spectral variation. Such MPCM-based progressive spectral signature coding (MPCM-PSSC) can be useful in applications such as hyperspectral data exploitation, environmental monitoring, and chemical/biological agent detection. Experiments are provided to demonstrate the utility of the MPCM-PSSC in signature discrimination and identification.The first author would like to acknowledge support received from his NRC National Research Council senior
research associateship sponsored by the U.S. Army Soldier
and Biological Command, Edgewood Chemical and Biological Center ECBC from 2002–2003.https://www.spiedigitallibrary.org/journals/optical-engineering/volume-45/issue-9/097002/Progressive-coding-for-hyperspectral-signature-characterization/10.1117/1.2353113.ful
Functionalization and characterization of cotton with phase change materials and thyme oil encapsulated in beta-cyclodextrins
No full textThe aim of this work was to study the production of comfortable cotton plain-weave fabrics withantibacterial and antifungal characteristics through a simple finishing process, which consists in apply-ing microcapsules of phase change materials (mPCM), monochlorotriazinyl- -cyclodextrin (MCT- -CD)and thyme oil. The fabrics were characterized by Infrared Spectroscopy (FTIR), Differential ScanningCalorimetry (DSC), Contact Angle and Infrared Thermography. The thyme oil release was also analyzed,as well as the antibacterial and antifungal activity. The materials treated with 20 L/mL of thyme oilhave shown anomalous oil release mechanisms, according to the Korsmeyer-Peppas model, and activityagainst Staphylococcus aureus, Escherichia coli, Trichophyton rubrum, Pseudomonas aeruginosa and Candidaalbicans.Therefore, it was reached the conclusion that mPCM, conjugated with thyme oil encapsulated in MCT- -CD, proved to be an interesting option to produce materials possessing thermoregulation propertieswith putative clinical relevance for the prevention of infections, particularly dermatophytosis.The main author wishes to express thanks to the CNPq-Brazil (Conselho Nacional de
Desenvolvimento Científico e Tecnológico – Brasil / National Council of Scientific and
Technological Development – Brazil) for the doctoral scholarship (233550/2014-3).
This work is also funded by FEDER funds through the Competitivity Factors Operational
Programme - COMPETE and by national funds through FCT – Foundation for Science and
Technology within the scope of the project POCI-01-0145-FEDER-007136
This research was partially supported by the Strategic Funding UID/Multi/04423/2013 through
national funds provided by FCT - Foundation for Science and Technology and European
Regional Development Fund (ERDF), in the framework of the program PT2020.info:eu-repo/semantics/publishedVersio
Experimental and numerical study on phase change material (PCM) for thermal management of mobile devices
No full textAs mobile devices become more complex and higher in performance despite the smaller size, heat concentration at localized areas has become a problem. In recent years, passive cooling using phase change materials (PCMs) has drawn attention as a thermal management method for mobile devices. PCMs reduce the temperature increase rate due to their latent heat properties. This reduction in the temperature increase rate is called a "delay effect". Moreover, microencapsulated PCMs (MPCMs) are attracting attention because they keep the melted PCMs from leaking. In this study, PCM sheets containing MPCM/polyethylene composite material are investigated for the thermal management of mobile devices. Namely the authors conduct a series of experiments using the PCM sheet with a high thermal conductivity sheet mounted into a simply modeled mobile device. Effects of the mass, the latent heat, the thermal conductivity, the configuration of the PCM sheet, and high thermal conductivity sheet on the temperature of a smart phone simulator are investigated. A finite element analysis (FEA) is also conducted considering the phase change of PCMs to investigate the optimal dimension and shape of PCMs. As a result, the delay effect of PCMs and the effectivity of a copper sheet pasted on the PCMs are verified by experiments. Moreover, FEA shows that using the PCM sheet with high thermal conductivity sheet has an advantage for the thermal management of mobile devices and gives an optimal condition for the PCM sheets
Safety and efficacy of non-steroidal anti-inflammatory drugs to reduce ileus after colorectal surgery.
No full textBackground: Ileus is common after elective colorectal surgery, and is associated with increased adverseevents and prolonged hospital stay. The aim was to assess the role of non-steroidal anti-inflammatorydrugs (NSAIDs) for reducing ileus after surgery.Methods: A prospective multicentre cohort study was delivered by an international, student- andtrainee-led collaborative group. Adult patients undergoing elective colorectal resection between Januaryand April 2018 were included. The primary outcome was time to gastrointestinal recovery, measuredusing a composite measure of bowel function and tolerance to oral intake. The impact of NSAIDs wasexplored using Cox regression analyses, including the results of a centre-specific survey of complianceto enhanced recovery principles. Secondary safety outcomes included anastomotic leak rate and acutekidney injury.Results: A total of 4164 patients were included, with a median age of 68 (i.q.r. 57–75) years (54⋅9 percent men). Some 1153 (27⋅7 per cent) received NSAIDs on postoperative days 1–3, of whom 1061 (92⋅0per cent) received non-selective cyclo-oxygenase inhibitors. After adjustment for baseline differences, themean time to gastrointestinal recovery did not differ significantly between patients who received NSAIDsand those who did not (4⋅6 versus 4⋅8 days; hazard ratio 1⋅04, 95 per cent c.i. 0⋅96 to 1⋅12; P = 0⋅360). Therewere no significant differences in anastomotic leak rate (5⋅4 versus 4⋅6 per cent; P = 0⋅349) or acute kidneyinjury (14⋅3 versus 13⋅8 per cent; P = 0⋅666) between the groups. Significantly fewer patients receivingNSAIDs required strong opioid analgesia (35⋅3 versus 56⋅7 per cent; P < 0⋅001).Conclusion: NSAIDs did not reduce the time for gastrointestinal recovery after colorectal surgery, butthey were safe and associated with reduced postoperative opioid requirement.</p
Safety and efficacy of non-steroidal anti-inflammatory drugs to reduce ileus after colorectal surgery
No full textBackground Ileus is common after elective colorectal surgery, and is associated with increased adverse events and prolonged hospital stay. The aim was to assess the role of non-steroidal anti-inflammatory drugs (NSAIDs) for reducing ileus after surgery. Methods A prospective multicentre cohort study was delivered by an international, student- and trainee-led collaborative group. Adult patients undergoing elective colorectal resection between January and April 2018 were included. The primary outcome was time to gastrointestinal recovery, measured using a composite measure of bowel function and tolerance to oral intake. The impact of NSAIDs was explored using Cox regression analyses, including the results of a centre-specific survey of compliance to enhanced recovery principles. Secondary safety outcomes included anastomotic leak rate and acute kidney injury. Results A total of 4164 patients were included, with a median age of 68 (i.q.r. 57-75) years (54 center dot 9 per cent men). Some 1153 (27 center dot 7 per cent) received NSAIDs on postoperative days 1-3, of whom 1061 (92 center dot 0 per cent) received non-selective cyclo-oxygenase inhibitors. After adjustment for baseline differences, the mean time to gastrointestinal recovery did not differ significantly between patients who received NSAIDs and those who did not (4 center dot 6 versus 4 center dot 8 days; hazard ratio 1 center dot 04, 95 per cent c.i. 0 center dot 96 to 1 center dot 12; P = 0 center dot 360). There were no significant differences in anastomotic leak rate (5 center dot 4 versus 4 center dot 6 per cent; P = 0 center dot 349) or acute kidney injury (14 center dot 3 versus 13 center dot 8 per cent; P = 0 center dot 666) between the groups. Significantly fewer patients receiving NSAIDs required strong opioid analgesia (35 center dot 3 versus 56 center dot 7 per cent; P < 0 center dot 001). Conclusion NSAIDs did not reduce the time for gastrointestinal recovery after colorectal surgery, but they were safe and associated with reduced postoperative opioid requirement
