Micro-encapsulated/macro-encapsulated phase change materials (Micro/MacroPCMs) are attractive environmental energy materials since they can be integrated into building materials, textile fabrics and ...heat-insulating materials to give their solar energy storage capacities and improve their temperature adjustment abilities. An innovative set of Micro/MacroPCMs has been designed using natural polymers, showcasing prowess in solar energy storage and UV protection. The eco-friendly bifunctional MicroPCMs are made up of paraffin as core and titanium dioxide (TiO2)-modified chitosan (CS) as shell. Their energy efficiency was elevated using a double emulsion technique. Alginate (ALG), an anionic polysaccharide, was selected as the matrix of the MacroPCMs to provide an enhanced combination with the cation polysaccharide CS shell. The surfaces and structures of the Micro/MacroPCMs were observed through SEM and image measurement (IM). Their chemical profile was deciphered using FTIR and XRD. Ultraviolet–visible spectrophotometry evaluated their UV resistance. DSC, TGA, and infrared thermography delved into their thermal attributes, while a texture analyzer revealed the mechanical strength of the MacroPCMs. The introduction of TiO2 resulted in a greater effective enthalpy and thermal stability. The energy storage ability of the MicroPCMs was further improved by using a double emulsification system. Notably, MicroPCMs crafted with TiO2-infused CS using the double emulsion approach stood out, boasting an impressive PCM content of 81.3 %, a melting enthalpy of 125.5 J/g, and commendable UV and thermal regulation capacities. With their robust thermal performance and mechanical resilience, these eco-friendly difunctional Micro/MacroPCMs emerge as prime contenders in solar energy conservation and temperature control applications.
•Paraffin was microencapsulated with titanium dioxide (TiO2)-modified chitosan shell.•Double emulsion method improved the encapsulation efficiency.•TiO2-modified MicroPCMs possess UV-shielding and temperature-regulated function.•MacroPCMs containing MicroPCMs in alginate display better compressive strength.
•A state-of-the-art apparatus is used to conduct experiments in full scale wall experiments simultaneously.•Four walls panels are constructed and tested in full cycles of heating and cooling.•One ...microencapsulated and two macroencapsulated PCMs are tested.•Experimental data from the four panels are made available for validation purposes.
Thermal energy storage (TES) is used as a viable technology to shift peak electricity demand caused by the space cooling requirements in buildings. Passive TES is implemented in building envelope via micro and macroencapsulation methods. This study describes the use of a state-of-the-art laboratory to test different PCM inclusions in simplified building walls. A microencapsulated PCM and two macroencapsulated PCMs are tested in a controlled environment to gather data for validation purposes of PCM modelling algorithms in building energy modelling programs. Data indicates that the chamber environment and the heating and cooling system can conduct full-cycle tests of wall panels with PCM inclusions. This study also generates data from parallel tests on 4 wall panels which can be used in building energy modelling programs to validate the PCM modelling algorithms. The cyclic tests also capture the thermal effects of PCMs and complex PCM behaviors like sub-cooling in PCM hydrate-salts.
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•Review on application of PCM in trombe wall was performed.•Incorporation of PCMs results in minimizing energy consumption of buildings.•The optimum PCM location into buildings ...depends on the climate.•Immersion and direct incorporation causes leakage due to heat cycles.•The encapsulation techniques have successfully overcome all of drawbacks.
Energy crises and environmental pollution are two of the cardinal obstacles that affect human life today. As part of the efforts to address the excessive energy demands in the last few decades is using renewable energy like solar. As the building sector continues to grow with the growing population, correspondingly, the demand for energy consumption required to heat and cool buildings for thermal comfort augments. To tackle this problem, techniques such as designing green buildings for sustainable architecture have been employed. One of these technologies is the Trombe wall which has been utilized as an avenue for heating buildings using renewable solar energy. Meanwhile, the practice of latent heat storage systems with phase change materials (PCM) is an efficient method to store energy. Substantial research has been carried out to assess the contribution of incorporation of latent heat storage and Trombe walls in buildings on their thermal energy performance. The present review paper communicates a summary of the recent advancements in this topic. The various designs of Trombe walls and different phase change materials types are presented. Research concerning the incorporation of PCM incorporation techniques is scrutinized. Finally, hitherto published literature regarding the applications of PCM in the Trombe wall is underscored and discussed.
Hydrogel cell encapsulation devices are a common approach to reduce the need for chronic systemic immunosuppression in allogeneic cell product transplantation. Macroencapsulation approaches are an ...appealing strategy, as they maximize graft retrievability and cell dosage within a single device; however, macroencapsulation devices face oxygen transport challenges as geometries increase from preclinical to clinical scales. Device design guided by computational approaches can facilitate graft oxygen availability to encapsulated cells in vivo but is limited without accurate measurement of oxygen levels within the transplant site and graft. In this study, we engineer pO2 reporter composite hydrogels (PORCH) to enable spatiotemporal measurement of oxygen tension within macroencapsulation devices using the proton Imaging of siloxanes to map tissue oxygenation levels (PISTOL) magnetic resonance imaging approach. We engineer two methods of incorporating siloxane oximetry reporters within hydrogel devices, an emulsion and microbead-based approach, and evaluate PORCH cytotoxicity on co-encapsulated cells and accuracy in quantifying oxygen tension in vitro. We find that both emulsion and microbead PORCH approaches enable accurate in situ oxygen quantification using PISTOL magnetic resonance oximetry, and that the emulsion-based PORCH approach results in higher spatial resolution.
Beta cell replacement has emerged as an attractive therapeutic alternative to traditional exogenous insulin administration for management of type 1 diabetes (T1D). Beta cells deliver insulin ...dynamically based on individual glycometabolic requirements, providing glycemic control while significantly reducing patient burden. Although transplantation into the portal circulation is clinically available, poor engraftment, low cell survival, and immune rejection have sparked investigation of alternative strategies for beta cell transplantation. In this review, we focus on current micro- and macroencapsulation technologies for beta cell transplantation and evaluate their advantages and challenges. Specifically, we comment on recent methods to ameliorate graft hypoxia including enhanced vascularization, reduction of pericapsular fibrotic overgrowth (PFO), and oxygen supplementation. We also discuss emerging beta cell-sourcing strategies to overcome donor shortage and provide insight into potential approaches to address outstanding challenges in the field.
Beta cell replacement is an attractive therapeutic alternative for management of T1D.Low cell survival and immune rejection have sparked investigation of alternative strategies for beta cell transplantation.Micro- and macroencapsulation technologies open new doors for beta cell transplantation.Strategies devoted to ameliorate graft hypoxia may help to address outstanding challenges in the field.
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•Prepares CPCM with g-C3N4 as a novel porous matrix to composite with Mg(NO3)2·6H2O.•G-C3N4 prevents liquid leakage and fully resolves the subcooling of Mg(NO3)2·6H2O.•Sealants ...covering the surface of the CPCM prevents dehydration of hydrated salt.•The coated CPCM have stable phase change characteristics after thermal cycling.
Mg(NO3)2·6H2O is a promising thermal energy storage material owing to its suitable melting point and high latent heat; however, it suffers from poor thermal stability owing to dehydration. This paper presents a two-step encapsulation method to prepare a shape-stabilized Mg(NO3)2·6H2O composite phase change material (CPCM). First, Mg(NO3)2·6H2O is infiltrated into a novel porous matrix – the graphitic carbon nitride (g-C3N4). The g-C3N4 provides a microhousing for Mg(NO3)2·6H2O to prevent liquid from leaking out during the solid–liquid phase change. The g-C3N4 also significantly reduces the sub-cooling degree of Mg(NO3)2·6H2O from 29.2 °C to 1.9 °C. The Mg(NO3)2·6H2O/g-C3N4 composite with 80 wt% Mg(NO3)2·6H2O has a phase change temperature of 87.0 °C and a specific phase change enthalpy of 112.30 kJ kg−1. Second, the Mg(NO3)2·6H2O/g-C3N4 composite is shaped into a cylinder and then macroencapsulated with commercial adhesive sealants (an epoxy resin structural adhesive and silicon sealant). The sealants provide a shell for the hydrated salt to prevent dehydration. After 100 thermal cycles, the composite phase change material only lost 0.84% and 6.25% in weight with coatings of epoxy resin and silicon sealant, respectively, which are much lower than the 22.92% for the uncoated composite phase change material. The specific phase change enthalpy of the composite phase change material barely changed after 100 cycles; however, the loss for the uncoated composite phase change material reached 22.47%. The joint effect of the g-C3N4 matrix and the sealants improve the thermal stability and reliability of the Mg(NO3)2·6H2O. This sequential multi-scale encapsulation method is promising for solving the typical problems of hydrated salts.
Frequent subcutaneous or intravenous administrations of therapeutic biomolecules can be costly and inconvenient for patients. Implantation of encapsulated recombinant cells represents a promising ...approach for the sustained delivery of biotherapeutics. However, foreign body and fibrotic response against encapsulation materials results in drastically reduced viability of encapsulated cells, presenting a major engineering challenge for biocompatibility. Here, we show that the multi-laminate electrospun retrievable macrodevice (Bio-Spun) protects genetically modified human cells after subcutaneous implant in mice. We describe here a biocompatible nanofiber device that limits fibrosis and extends implant survival. For more than 150 days, these devices supported human cells engineered to secrete the antibodies: vedolizumab, ustekinumab, and adalimumab, while eliciting minimal fibrotic response in mice. The porous electrospun cell chamber allowed secretion of the recombinant antibodies into the host bloodstream, and prevented infiltration of host cells into the chamber. High plasma levels (>50 μg/mL) of antibody were maintained in the optimized devices for more than 5 months. Our findings demonstrate that macrodevices constructed from electrospun materials are effective in protecting genetically engineered cells for the sustained administration of recombinant therapeutic antibodies.
•Implantable cell devices are a retrievable alternative to in vivo gene therapy.•Fibrotic overgrowth of implants has hampered clinical implementation of cell devices.•Cell macroencapsulation with electrospun materials modulates foreign body response.•Recombinant cells in electrospun devices show long-term high mAb secretion.•The Bio-Spun device provided immune protection with minimal fibrotic reaction.
•Investigation on the thermal behavior of different designs of PCM packages included in concrete blocks.•Changing the PCM design enables a desired adjustment of the thermal behavior of concrete ...blocks.•Thin and set up positioned PCM layers generate fast crystallization and melting times compared to massive PCM blocks.•Flat overlaid PCM packages generate a thermal shading effect leading to longer melting and crystallization periods.•Macroencapsulated PCM packages can be positioned to achieve the most positive thermal effect.
Most installed phase change materials in real applications are typically spherical microencapsulated paraffin. However, salt hydrates can be a cheap alternative when combined with a suitable macroencapsulation. Such macroencapsulation enables the installation of different shapes and positions within the building material. Therefore, an experiment setup consisting of a wooden box equipped with infrared radiators and a cooler was used to investigate cuboid, cylindrical, plate-shaped, and spherical phase-change packages. All water vapor impermeable packages filled with salt hydrate were positioned within a standard concrete block. As a result, it can be seen that changing the design of a PCM package enables the opportunity to adjust the thermal behavior without changing the mass of the PCM. For a high heat transfer, a set up position of a large number of thin packages with a large heat transfer surface was found to be the best design. Using a thermal shading effect and an even distribution of the PCM within concrete block ensures a slow increase in the temperature of the block and thus a lower heat flow into the inner rooms.
Type 1 Diabetes Mellitus (T1DM) is characterized by the autoimmune destruction of β-cells in the pancreatic islets. In this regard, islet transplantation aims for the replacement of the damaged ...β-cells through minimally invasive surgical procedures, thereby being the most suitable strategy to cure T1DM. Unfortunately, this procedure still has limitations for its widespread clinical application, including the need for long-term immunosuppression, the lack of pancreas donors and the loss of a large percentage of islets after transplantation. To overcome the aforementioned issues, islets can be encapsulated within hydrogel-like biomaterials to diminish the loss of islets, to protect the islets resulting in a reduction or elimination of immunosuppression and to enable the use of other insulin-producing cell sources. This review aims to provide an update on the different hydrogel-based encapsulation strategies of insulin-producing cells, highlighting the advantages and drawbacks for a successful clinical application.
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