Foam Strips Research Articles

Benchtop assessment of sealing efficacy and breathability of additively manufactured (AM) face masks.

The onset of the 2019 novel coronavirus disease (COVID-19) led to a shortage of personal protective equipment (PPE), medical devices, and other medical supplies causing many stakeholders and the general public alike to turn to additive manufacturing (AM) as a stopgap when normally accessible devices were not available. However, without a method to test these AM constructs, there continued to be a disconnect between AM suppliers and the community's needs. The objective of this study was to characterize the pressure drop and leakage of four different publicly available AM face mask models with two filter material combinations, as well as to investigate the impact of frame modification techniques including the use of foam strips and hot-water face forming to improve fit when the masks are donned on manikin head forms. AM face mask frame designs were downloaded from public repositories during the early stages of the COVID-19 pandemic. AM face masks were fabricated and tested on manikin head forms within a custom chamber containing dry aerosolized NaCl. Pressure drops, particle penetration, and leakage were evaluated for various flow rates and NaCl concentrations. Results indicated that filter material combination and frame modification played a major role in the overall performance of the AM face masks studied. Filter material combinations showed improved performance when high filtration fabric was used, and the cross-sectional area of the fabric was increased. AM frame modifications appeared to improve AM face mask leakage performance by as much as 69.6%.

A hybrid solidification enhancement in a latent-heat storage system with nanoparticles, porous foam, and fin-aided foam strips

The relatively high storage density and negligible temperature stratification of phase-changing materials (PCMs) facilitate their application as storage modules for managing the mismatch between energy generation and consumption. The poor heat diffusivity of these materials limits their storage effectiveness, and therefore employing efficient thermal enhancers is required. This study examines the fin-aided foam strip as a hybrid enhancer for overcoming the relatively low thermal response of erythritol as PCM in a triple-pipe containment system. Four different enhancement additives, including porous foam, graphene nanoparticles, longitudinal fins, and foam strips within the same volume limitations, were compared and tested via applying an experimentally validated simulation model to verify the functionality of the proposed thermal enhancers. The results show that the inclusion of full foam, fin arrays, and fin-assisted foam strips substantially enhances the solidifying behaviour of PCM as compared to the inclusion of nanoparticles alone. The solidifying time can be decreased by 60.8 %, 63.2 %, and 77.3 %, while the recovery rate can be increased by 152.9, 171.6 %, and 340.1 %, respectively. The results also suggest that increasing the length of strips while decreasing their thickness can further enhance the thermal response of PCM for solidification within the same volume limitations.

Supercritical CO 2 foaming of open‐cell polypropylene/ethylene propylene diene monomer composite foams with oriented cellular structures for water treatment

Efficient treatment of tiny media in wastewater is a global challenge. Herein, an ingenious design to fabricate the highly open-cell polypropylene (PP)/ethylene propylene diene monomer (EPDM) composite foams for water treatment by using supercritical CO2 (scCO2) extrusion foaming coupling with post-stretching is presented. The tensile strain of high melt strength PP is fully utilized in an extensional flow field during foaming. Meanwhile, EPDM is added into PP matrix for obtaining the highly open-cell and oriented porous structures. Interestingly, a variety of structural transformations (like uniform, hollow and oriented cellular structures) can be achieved during extrusion foaming. Furthermore, the effects of different cellular structures on their selective filtration properties are studied. More interestingly, the as-prepared composite foam strips, with the highly open-cell content (~94.4%) and orientation degree (~89.6%), exhibit excellent selective filtration performance, which can successfully remove waste with particle size larger than 1 μm (its filtration efficiency:~ 99.52%). Water droplets can easily pass through the lengthy foam strips in seconds, but tiny particles (like oil droplets or glass microbeads) will be blocked. This work provides a new pathway to prepare highly open-cell composite foams with anisotropic porous structures for water treatment.

Performance evaluation of ammonia-fueled flat-tube solid oxide fuel cells with different build-in catalysts

The corrosion of ammonia atmosphere to Ni-cermet anode significantly affects the performance and durability of direct ammonia fuel solid oxide fuel cells. In this study, we investigate the impedance behavior of the flat-tube solid oxide fuel cells (SOFCs) fed with pure ammonia in details, assisted with distributions of relaxation time analysis under different fuels, operating temperatures, flow rates, and cell voltages. In addition, we use Ni/Al2O3 particles and nickel foam strips as the built-in catalysts to enhance ammonia decomposition within the anode support of the flat-tube cells. It is confirmed that the increased catalytic activity of ammonia decomposition brought by the built-in catalyst and the change of internal fuel gas resistance would affect the initial performance of the cell. In addition, enhancing the catalytic activity of ammonia decomposition through the built-in catalyst could effectively inhibit the corrosion effect of ammonia on the Ni surface in the anode support, thus enhancing the long-term durability of ammonia-fueled SOFC.

Extruded polypropylene foams with radially gradient porous structures and selective filtration property via supercritical CO2 foaming

Original polypropylene (PP) foams with radially gradient porous structures and selective filtration were developed through the supercritical CO2 assisted extrusion foaming couple with the stretching auxiliary. Firstly, the relationship among the physical characteristics, processing technology and microstructure of the polymer foams were studied. Specially, the effect of the tensile strain hardening and its spatial confinement of the high melt strength PP (HMSPP) in the extensional flow field on the condensed matter physics and foaming behavior of the polymer foams were revealed. Remarkably, the orientation degree of the modified PP foams could be ~47.2 higher than the traditional ones in different zones. Secondly, the compression experiments and theoretical calculated analysis showed the mechanical properties of the as-prepared PP foams exhibited obvious directionality, which is beneficial to recycle and squeeze wastewater. Besides, the corresponding characterization methods and self-made filter device were used to demonstrate the selective filtration performance of the as-prepared PP foams. Interestingly, the water droplet could pass the 3D lengthy PP foam strips, while the ultrafine wasted materials were blocked due to the unique micro-structures. Gradient porous polymer foams without any modification are firstly demonstrated to be interesting materials with the potential applications in the selective filtration properties.

Intensifying the thermal response of PCM via fin-assisted foam strips in the shell-and-tube heat storage system

An approach for intensifying the thermal response of phase-change materials (PCMs) in the shell-and-tube containment system via applying fin-assisted foam strips was proposed in this paper. The thermal response of these materials to energy storage and recovery duties is inherently limited due to their high thermal resistance. To support better thermal communication between the tube carrying the heat-transfer fluid and PCM in charge, this study suggests applying a fin array with foam strips. The use of foam strips rather than full foam was suggested since they require less material and can achieve better enhancement rate as they can operate in a more convection-friendly environment. The proposed approach was successfully tested and verified by comparing the enhanced melting and solidification rates between four different enhancement additives within the same volume limitations. These additives were: foam alone, fins alone, even fins with foam strips, and uneven fins with foam strips. A computational model that took into account the impact of the convective flow of PCM and the non-Darcy flow in foam strips was applied and validated via previous research. The results revealed that the uneven fins with foam strips had the best enhancement potential when compared to other additives in use. It was found that the melting rate could be enhanced up to 58 % and the corresponding solidification rate could be enhanced up to 42 % depending on the type and volume fraction of the enhancement additive used.

Resistance of ETICS with Fire Barriers to Cyclic Hygrothermal Impact

The article presents the results of a set of hygrothermal experiments of an external wall insulated with an ETICS. As an add-on to previous studies, thermal insulation in the form of polystyrene with an additional horizontal strip of mineral wool was used. Laboratory tests were carried out in accordance with ETAG 004. The ETICS test rig was composed of combustible expanded polystyrene foam (EPS) and horizontal strips of noncombustible mineral wool (MW) fire barriers over windows. The physical and mechanical properties of four types of finishing renders (without an additional reinforcement mesh in base coat of the fire barriers) were analyzed across full hygrothermal cycles in a climate chamber. Temperature sensors were mounted onto different ETICS layers to collect thermal data during the weathering. The testing of ETICS regarding their hygrothermal performance revealed that there were no visible defects on any renderings and over the junctions depending on the type of used insulation materials. Results also showed that the joints of EPS and MW have approximately half of their bond strength from polystyrene strength.

Comparative study on the feasibility of watertight face-sealed building joints under simulated wind-driven rain conditions

ABSTRACT Although several field studies have indicated that water penetration can be expected through face-sealed joints over the lifespan of buildings, in particular, when sealed by means of construction sealant, face-sealed systems are still being applied by industry, e.g. precast concrete panels. Laboratory studies evaluating the concept of face-sealed joints are, however, limited. This study assesses and compares the initial performance of four sealing systems, tapes, silicone strips, silicone-based coating and foam sealing strips, applied to seal building joints in a face-sealed manner and subjected to simulated wind pressures and driving rain loads. The results give insight into the initial watertightness of the sealing materials and the sensitivity of the performance of the materials to different installation methods. The results indicate that water leakage can be expected through unperceivable openings in the face-sealed joints and that great care should be taken to install the sealing materials in the correct manner. The findings also suggest that closed-cell foam strips might be considered as an alternative to construction sealant to face-seal joints. Further research should evaluate the performance of these foam sealing strips after natural weathering and exposure to cyclic building movements.

Numerical thermal performance of free convection in metal foam heat sinks with fin edges

This study introduces numerical investigation of natural convection in metal foam heat sinks with two types of fin edges namely fillet and sharp edges. Aluminum metal foam of various pore densities (5, 10, 20 PPI) and sets of porosities ( ) are used in the simulations. The dimensions of the samples were 100 mm length, 100 mm height, 10 mm thickness and the spacing between fins were kept at 8 mm. Then the metal foam strips were installed onto an aluminum base plate (100 * 100 * 3.5 mm3). The investigation has been performed by control volume method . As well as, the energy equations are established on a principle that based on a local thermal non-equilibrium (LTNE) model in which the temperature of the fluid and the solid matrix are solved separately. The heat input was different from 4 to 30 W in numerical runs and the air was used as a working fluid. The results show that the base temperature of the heat sink is lower for the new design of edges. Therefore, the proposed approach of the heat sink has significant potential to be utilized to enhance the thermal performance of heat sinks and thereby to develop more advanced effective cooling devices and techniques. The maximum enhancement of the heat transfer coefficient with fillet profile reached 5.6% greater than fins with sharp edges

Biodegradable polyurethanes foam and foam fullerenes nanocomposite strips by one-shot moulding: Physicochemical and mechanical properties

Biodegradable polyurethanes foam as well as foam strips have been formulated by the renowned one-shot process. Commercially available biodegradable trifunctional polyol, polycaprolactone triol (major, ~77 wt%) and isophorone diisocyanate were chosen to react in the presence of other essential components to formulate the PU foams from the paper cup as well as foam strips using mould at ambient temperature. The formulation of foams has been efficiently attempted by successive steps by alteration of the components such as chain extender, quantity of water and isocyanate index. In situ addition of fullerenes (0.1, 0.4 and 1.0 wt%) into the composition of PU foam strips formulation in mould found to afford the three samples of PU-fullerenes nanocomposite. In case of polyurethanes-fullerenes nanocomposite foam strips, nanomaterial of fullerenes was identified to disperse uniformly in the bulk of sample to incorporate the enhancement in physicochemical and mechanical properties value as compared to the control PU foam strip. The battery of analyses such as physicochemical, morphological and mechanical properties was studied for each foam samples, including control and PU-fullerenes nanocomposite strips. Solid state carbon-13 nuclear magnetic resonance spectral data for the foam revealing desired properties was collected to corroborate the chemical functional groups in the molecular structure network.

The effect of transcatheter bronchial artery embolization in five patients with bronchial artery aneurysm.

IntroductionDue to its rarity and the lack of animal models for this disease, the etiology of bronchial artery aneurysm (BAA) is poorly understood.AimTo investigate the effect of transcatheter artery embolization (TAE) with coils, spherical polyvinyl alcohol (PVA), and gel foam in patients with BAA.Material and methodsFrom June 2015 to November 2018, 5 patients diagnosed with BAA with massive hemoptysis after undergoing bronchial arteriography and receiving TAE therapy in the Department of Interventional Radiology were enrolled in this study. Post-embolization angiography was used to demonstrate total occlusion of the BAAs and bronchiectatic engorged vessels. The patients’ follow-up was conducted 1–16 months after TAE.ResultsAll 5 patients were cured by the TAE treatment, during which PVA, coils, and gel foam were applied. The patients also received successful TAE via a microcatheter. Hemoptysis disappeared in all patients. No special or severe complications occurred, and no patient experienced a recurrence during the follow-up.ConclusionsOverall, TAE is the best choice for patients with hemoptysis and BAA due to its effectivity and reliability. Thorough and complete embolization of the bleeding arteries is the key to successful treatment. Though PVA and coils are the most common materials for embolization, gel foam strips can also be applied.

Operative and environmental performance of a hot-foam machine for the herbicide-free weeding of the vineyard

The elimination of chemical herbicides use is a key factor in vineyards, particularly in the case of biological cultivation. The machines employed for mechanical weeding under the vine row are often characterised by low travelling speeds and therefore also by a low working capacity. A new solution is the application of hot foam, to transmit heat to weeds. A hot-foam machine for the herbicide-free weeding of vineyards was then developed, to produce and deposit foam directly onto weeds. The foam strips produced were approximately 40 cm width and 20-25 cm height, with a temperature exceeding 75°C. The future success of this environmentally sustainable technique will be the identification of a 100% naturally biodegradable and long-lasting foam, to maximize heat transmission to weeds.

Does the addition of adjuvant intraoperative tumor bed chemotherapy during midgut neuroendocrine tumor debulking procedures benefit patients?

Midgut neuroendocrine tumor (NET) patients are often diagnosed at advanced stages with extensive mesenteric nodal and hepatic metastasis. The only potentially curative treatment is surgical tumor eradication. Despite an aggressive resection, macro and microscopic residual disease still may remain in the resection bed. We hypothesize that the application of 5-fluorouracil (5-FU) within the tumor bed will help eliminate microscopic residual disease. Records of 189 patients who underwent extensive cytoreductive surgeries during 2003-2012 for advanced, midgut NETs with extensive mesenteric lymphadenopathy were reviewed. Eighty-six patients (46%) who had 5-FU saturated gel foam strips secured into their mesenteric resection sites served as the study group and a matching 103 patients (54%) who did not have such an intra-operative chemotherapy served as controls. Survival from the time of diagnosis and post-operative complications between the two groups were compared. Mortality rates at 30, 60 and 90 days post-operatively were 4%, 0%, 0% versus 2%, 0%, 2% for study and control groups, respectively. Major complications (Grades III & IV) at the same intervals were 0, 0, 1 versus 2, 3, 2 for study and control groups, respectively. Median survival was 236 months versus 148 months for the study and control groups, respectively 24 (P=0.15). Intraoperative tumor resection bed chemotherapy is a safe adjuvant without discernible toxicity. This procedure may provide survival benefits to midgut NET patients with extensive mesenteric lymphadenopathy undergoing extensive cytoreductive surgery. Further study in prospective trials must be conducted to determine definitive benefit to the NET patient.

Bio-inspired lightweight polypropylene foams with tunable hierarchical tubular porous structure and its application for oil-water separation

Inspired by nature, the biomimetic polypropylene (PP) foams with tunable hollow tubular structure, hierarchical porous structure and rough inner surface characteristics were designed and massively fabricated (with a speed exceed 0.5 m/s) via environment-friendly supercritical carbon dioxide (scCO2) continuous extrusion foaming. Additionally, the inner diameter of the as-prepared biomimetic tubular PP foams can be easily adjusted from extreme low (∼0.4 mm) to very high (∼20.0 mm) size through a fixed 2.0 mm circle extruder die by carefully controlling the radially distributed temperature and melt viscoelasticity. Furthermore, we also theoretically analyzed the reasons of the formation of such biomimetic hierarchical tubular structure during foaming and drew up the corresponding schematic diagram. More interestingly, thanks to the above biomimetic structure, the as-prepared PP foam strips exhibited both superior absorption and filtration ability during the oil-water separation, in which the deionized water could be filtered quickly through the foam strips while the oil was absorbed in seconds. Besides, the relationship between pore size and hydrophobicity of polymer foams was theoretically analyzed by the Young-Laplace equation. More importantly, we believe that the design principles and processing strategies reported here can also be applied to other materials and it has great potential application in the environmental sewage treatment.

Natural convection in metal foam heat sinks with open slots

Natural convection in metal foam heat sinks with open slots was investigated experimentally. The test sample was made in-house by attaching several foam strips having fixed width of 10mm and length of 100mm onto a substrate of 100×100×4mm3 in size. A total of 29 test samples with different slot widths (s=0/2.86/5/8/12.5/20mm) and foam heights (H=10/20/40/60/80mm) were tested under both horizontal and vertical orientations for each sample. The zero width of open slots corresponds to a heat sink with a single foam block as considered in open literature, while the non-zero open slot width 2.86/5/8/12.5/20mm corresponds to 8/7/6/5/4 foam strips in a heat sink, respectively. Compared to a single foam block, the foam with open slots are more permeable for air penetrating through the heat sink. More foam strips means more heat transfer area available but less permeation of the heat sink. Experimental results revealed that there exists an optimum open slot width (5–8mm) for maximum heat transfer coefficient at given heat sink volume. With optimum open slot width, the heat transfer coefficient is enhanced by 14.9%, 21.3%, 37.6%, and 38.2% relative to single foam block (s=0mm) at the foam height of 10mm, 20mm, 40mm, and 80mm, respectively.

Redesign of a soft conductive rubber strip electrode for measurement of surface resistance according to IEC 60079-32-2 within the context of the PTB Ex Proficiency Testing Scheme

To ensure worldwide quality and homogeneity in the field of explosion protection, not only uniform rules in the form of IEC standards but also the active participation in interlaboratory comparisons are necessary. The “PTB Ex Proficiency Testing Scheme” is the first global proficiency testing program of its kind in the field of explosion protection. It serves as proof of competence and provides laboratories with a complete system for their own performance evaluation.In 2015, the program “Electrostatic Charge - Test Round 2015” was launched within the PTB Testing Scheme. The participants of the program performed surface resistance and transferred charge tests according to IEC 60079-0 and IEC 60079-32-2 on various types of test samples. The new standard IEC 60079-32-2 proposes different kinds of electrodes for the user, such as conductive silver paint electrodes, soft conductive rubber strip electrodes on spring-mounted metal tongues or conductive foam strips mounted on an insulating support, depending on the geometry of the sample. These different types of electrodes as well as the construction latitude for each electrode could lead to deviations between the results of different test laboratories due to better or worse electrode contact with the test sample.Therefore, the proficiency team and electrostatic experts at PTB decided to design an accurate and user-friendly electrode which meets the requirements of IEC 60079-32-2. This paper provides information about the electrodes' design as well as the results of comparable measurements.

Prevention of tumor seeding during needle biopsy by chemotherapeutic-releasing gelatin sticks

Needle biopsy is an indispensable diagnostic tool in obtaining tumor tissue for diagnostic examination. Tumor cell seeding in the needle track during percutaneous needle biopsies has been reported for various types of cancers. The mechanical force of the biopsy both directly displaces the malignant cells and causes bleeding and fluid movement that can further disseminate cells. To prevent the risk of tumor cell seeding during biopsy, we developed a gelatin stick loaded with chemotherapeutics such as doxorubicin (DXR) that was inserted into the biopsy canal. The gelatin-doxorubicin sticks (GDSs) were created by passively loading precut gelatin foam strips (Gelfoam) with doxorubicin solution. The dried GDSs were inserted into the needle track through the sheath during the needle biopsy and eventually self-absorbed. We showed that this procedure prevented iatrogenic tumor seeding during needle biopsies in two subcutaneous tumor models. In an alternative application, using GDSs in intracranial brain tumor implantation avoided the outgrowth of tumor from the rodent brain, which could otherwise potentially fuse the tumor with the meninges and distort the results in therapeutic studies in rodent brain tumor models.

Результаты натурных исследований огнезадерживающих свойств противопожарных пенных полос долговременного действия и средств для их прокладки

Результаты натурных исследований огнезадерживающих свойств противопожарных пенных полос долговременного действия и средств для их прокладки

Результаты лабораторных исследований свойств быстротвердеющей пены с целью оценки возможности использования её для создания противопожарных пенных полос

Результаты лабораторных исследований свойств быстротвердеющей пены с целью оценки возможности использования её для создания противопожарных пенных полос

3-D observations of a red tide event in the offshore water along the western Guangdong coast

From November 24 to 26, 2014, a red tide event occurred in the offshore water off the Hailing Island located at the western Guangdong coast. The red tide appeared as pink strips distributed within 3 km in the offshore water and extended for about 10 km along the shoreline. During the flood tide, the pink seawater rushed to the beach with breaking waves, forming foam strips on the beach. Guangdong Province Key Laboratory for Coastal Ocean Variation and Disaster Prediction Technologies, Guangdong Ocean University, emergently responded to the event and organized three-dimensional observations from the air, onboard and on beach. The preliminary analyses of the cruise data and water samples indicate that the event was induced by nontoxic Noctiluca scintillans, of which the concentration reaches as high as 4 200 cells/L near the surface and 2 600 cells/L at the bottom.