Search Results (15)

One crucial property of concrete, particularly in construction, is its thermal conductivity, which impacts heat transfer through conduction. For example, reducing the thermal conductivity of concrete can lead to energy savings in buildings. Various techniques exist for measuring the thermal conductivity of materials, but there is limited discussion in the literature about suitable methods for concrete. In this study, the transient line source method is employed to evaluate the thermal conductivity of concrete samples with natural and synthetic fibers after 7 and 28 days of curing. The results indicate that concrete with hemp fiber generally exhibits higher thermal conductivity values, increasing by 48% after 28 days of curing, while synthetic fibers have a minimal effect. In conclusion, this research opens the door to using natural alternatives like hemp fiber to improve concrete’s thermal properties, providing alternatives for thermo-active foundations and geothermal energy piles which require high thermal conductivities. Full article

A novel thermoactive phosphatidylcholine-specific phospholipase C (PC-PLC_Bs) was identified from Bacillus stearothermophilus isolated from a soil sample from an olive oil mill. Enhanced PLC_Bs production was observed after 10 h of incubation at 55 °C in a culture medium containing 1 mM of Zn²⁺ with an 8% inoculum size and 6 g/L glucose and 4/L yeast extract as the preferred carbon energy and nitrogen sources, respectively. PLC_Bs was purified to homogeneity by heat treatment, ammonium sulfate fractionation, and anion exchange chromatography, resulting in a purification factor of 17.6 with 39% recovery. Interestingly, this enzyme showed a high specific activity of 8450 U/mg at pH 8–9 and 60 °C, using phosphatidylcholine PC as the substrate, in the presence of 9 mM sodium deoxycholate and 0.4 mM Zn²⁺. Remarkable stability at acidic and alkali pH and up to 65 °C was also observed. PLC_Bs displayed a substrate specificity order of phosphatidylcholine > phosphatidylethanolamine > phosphatidylserine > sphingomyelin > phosphatidylinositol > cardiolipin and was classified as a PC-PLC. In contrast to phospholipases C previously isolated from Bacillus strains, this PLC_Bs substrate specificity was correlated to its hemolytic and anti-bacterial potential against erythrocytes and Gram-positive bacterial membranes, which are rich in glycerophospholipids and cardiolipin. An evaluation of PLC_Bs soybean degumming process efficiency showed that the purified enzyme reduced the phosphorus content to 35 mg/kg and increased the amount of diacylglycerols released, indicating its ability to hydrolyze phospholipids in the crude soybean oil. Collectively, PLC_Bs could be considered as a potential catalyst for efficient industrial oil degumming, advancing the edible oil industry by reducing the oil gum volume through transforming non-hydratable phospholipids into their hydratable forms, as well as through generating diacylglycerols, which are miscible with triacylglycerols, thereby reducing losses. Full article

The Fourth Industrial Revolution forms a smart grid with diverse sources of energy through the interconnectivity of data. Buildings that were previously the biggest users of energy are now becoming energy producers. Yet, buildings are also continually changing. The ecological definition of buildings, in addition to the building itself, includes solar panels and geothermal energy storage. The need for decarbonization and energy-efficiency brought about the implementation of heat pumps in buildings. The most economic type of heat pump is a water-sourced heat pump with hot and cold tanks or a connection to the District Energy System. Monitoring using building automatics allows HVAC optimization in the occupancy stage. Until the SARS-CoV-2 pandemic, the EU and the US differed in their air handling methodology, but the pandemic showed the limitations of both approaches and led to the creation of a new, integrated approach. These new ventilation systems, based on filtration instead of dilution, come together with decarbonization and the demand for new and retrofitted buildings to be smart, have zero emissions and excellent indoor environments, and be affordable. To fulfill these conditions, design teams must extrapolate experience with passive houses and introduce expertise in building automatic controls (BAC). The authors analyze the heating cooling and ventilation aspects of dwellings in a technology called Ecological Thermo-Active (ETA) technology that can also be applied to the interior retrofitting of buildings, including those with historic facades. The building “with classic form and ultramodern function” is an example of this changing design paradigm. Full article

Thermostability is important for the thermoactivity of proteins including enzymes. However, it is still challenging to pinpoint the specific structural factors for different temperature thresholds to initiate their specific structural and functional perturbations. Here, graph theory was used to investigate how the temperature-dependent noncovalent interactions as identified in the structures of aldolase B and its prevalent A149P mutant could form a systematic fluidic grid-like mesh network with topological grids to regulate the structural thermostability and the functional thermoactivity upon cyclization against decyclization in an extended range of a subunit. The results showed that the biggest grid may determine the melting temperature thresholds for the changes in their secondary and tertiary structures and specific catalytic activities. Further, a highly conserved thermostable grid may serve as an anchor to secure the flexible active site to achieve the specific thermoactivity. Finally, higher grid-based systematic thermal instability may disfavor the thermoactivity. Thus, this computational study may provide critical clues for the structural thermostability and the functional thermoactivity of proteins including enzymes. Full article

The use of phase-changing materials (PCMs) is a practical and powerful way of buffering thermal fluctuations and maintaining the isothermal nature of the storage process. In this study, melamine formaldehyde microcapsules with paraffin cores were used as PCMs; pullulan films with PCMs were prepared by the film-casting method; and the composite films prepared were analysed with regard to their chemical structure, thermal properties, thermal stability, and recyclability. Uniform films displaying thermal management functionality were prepared. The amount of 75 wt.% PCM were added to the pullulan film structure which enabled the preparation of a composite film that displayed 104.85 J g⁻¹ of heat storage during heating and 103.58 J g⁻¹ of heat release during cooling. Multiple heating and cooling cycles showed that the composite films maintained their thermal management functionality after multiple heating-cooling cycles. The PCMs could be recovered with a yield of approximately 95% by the application of a simple dissolution and filtration process. The morphology, chemical structure, and thermal properties of the PCMs were maintained after the recovery process. The bio-based composite films with thermal management functionality and recyclability are proposed as an innovative, practical, and effective system for thermoactive storage and packaging applications. Full article

L-asparaginase (L-ASNase) is a vital enzyme with a broad range of applications in medicine, food industry, and diagnostics. Among various organisms expressing L-ASNases, thermophiles and hyperthermophiles produce enzymes with superior performances—stable and heat resistant thermo-ASNases. This review is an attempt to take a broader view on the thermo-ASNases. Here we discuss the position of thermo-ASNases in the large family of L-ASNases, their role in the heat-tolerance cellular system of thermophiles and hyperthermophiles, and molecular aspects of their thermoactivity and thermostability. Different types of thermo-ASNases exhibit specific L-asparaginase activity and additional secondary activities. All products of these enzymatic reactions are associated with diverse metabolic pathways and are important for mitigating heat stress. Thermo-ASNases are quite distinct from typical mesophilic L-ASNases based on structural properties, kinetic and activity profiles. Here we attempt to summarize the current understanding of the molecular mechanisms of thermo-ASNases’ thermoactivity and thermostability, from amino acid composition to structural–functional relationships. Research of these enzymes has fundamental and biotechnological significance. Thermo-ASNases and their improved variants, cloned and expressed in mesophilic hosts, can form a large pool of enzymes with valuable characteristics for biotechnological application. Full article

Thermo-active piles are an upcoming technology for the utilization of subsurface geothermal energy in urban areas. This environmentally friendly technology has already been widespread for the heating and cooling of buildings in temperate regions, whereas in tropical regions it is still limited due to their unbalanced energy demands. This paper presents 3D thermo-hydraulic coupled numerical simulations to assess the long-term performance of thermo-active pile systems in tropical environments for different energy demands. The simulations are based on real data (in situ tests and field investigations) considering three typical thermal solicitations, thereby maintaining their practical relevance. Moreover, the energy exchange within soil control volumes is quantified based on an approach that allows calculating conductive and advective divergence. Parametric analyses regarding thermal solicitation, pile diameter, and groundwater flow are also performed. The results indicate that groundwater flow plays the most important role in improving the thermal balance of thermo-active piles. Full article

To improve the thermal stability of pectate lyase for ramie degumming, we modified the novel pectate lyase gene (pelG403) derived from the Dickeya dadantii DCE-01 high-efficiency ramie degumming strain by site-directed mutagenesis. Twelve mutants were acquired, wherein a prospective mutant (A129V) showed better enzyme activity and thermal stability. Compared with the wild type (PelG403), the specific enzyme activity and the optimal reaction temperature of A129V in the fermentation broth increased by 20.1%, and 5 °C, respectively. Under the conditions of 55 °C and pH 9.0, the weightlessness rate of ramie raw materials of A129V increased by 6.26%. Therefore, this study successfully improved the enzyme activity and heat resistance of PelG403 in an alkaline environment, which may contribute to the development of enzyme preparations and the elucidation of the mechanism for ramie bio-degumming. Full article

Understanding protein stability is critical for the application of enzymes in biotechnological processes. The structural basis for the stability of thermally adapted chitinases has not yet been examined. In this study, the amino acid sequences and X-ray structures of psychrophilic, mesophilic, and hyperthermophilic chitinases were analyzed using computational and molecular dynamics (MD) simulation methods. From the findings, the key features associated with higher stability in mesophilic and thermophilic chitinases were fewer and/or shorter loops, oligomerization, and less flexible surface regions. No consistent trends were observed between stability and amino acid composition, structural features, or electrostatic interactions. Instead, unique elements affecting stability were identified in different chitinases. Notably, hyperthermostable chitinase had a much shorter surface loop compared to psychrophilic and mesophilic homologs, implying that the extended floppy surface region in cold-adapted and mesophilic chitinases may have acted as a “weak link” from where unfolding was initiated. MD simulations confirmed that the prevalence and flexibility of the loops adjacent to the active site were greater in low-temperature-adapted chitinases and may have led to the occlusion of the active site at higher temperatures compared to their thermostable homologs. Following this, loop “hot spots” for stabilizing and destabilizing mutations were also identified. This information is not only useful for the elucidation of the structure–stability relationship, but will be crucial for designing and engineering chitinases to have enhanced thermoactivity and to withstand harsh industrial processing conditions Full article

Energy storage pile foundations are being developed for storing renewable energy by utilizing compressed air energy storage technology. Previous studies on isolated piles indicate that compressed air can result in pressure and temperature fluctuations in the pile, which can further affect safety of the pile foundation. Meanwhile, the temperature changes and distributions for the pile and surrounding soil also are influenced by adjacent piles in typical group pile constructions. Therefore, dynamic thermal transfer simulations were conducted in this paper to investigate the temperature changes and distributions in the concrete pile and surrounding soil for group pile construction. The main parameter in this study is the spacing of the piles. The analysis results show that the group pile effect significantly increases the temperature up to more than 100 °C depending on the location and changes its distribution in both concrete and soil due to the heat transferred from the adjacent piles. The final stabilized temperature can be as high as 120 °C in the concrete pile and 110 °C in the soil after numerous loading cycles, which is about 4 times higher than typical thermo-active energy pile applications. Thus, it is important to include the group pile effect for design and analysis of the energy storage pile foundation. Full article

Microorganisms present in Antarctica have to deal not only with cold temperatures but also with other environmental conditions, such as high UV radiation, that trigger the generation of reactive oxygen species. Therefore, Antarctic microorganisms must have an important antioxidant defense system to prevent oxidative damage. One of these defenses are antioxidant enzymes, such as catalase, which is involved in the detoxification of hydrogen peroxide produced under oxidative conditions. Here, we reported the isolation and partial characterization of an Antarctic bacterium belonging to the Serratia genus that was resistant to UV-C radiation and well-adapted to cold temperatures. This microorganism, denominated strain I1P, was efficient at decreasing reactive oxygen species levels produced after UV-C irradiation. Genomic and activity assays suggested that the enzymatic antioxidant defense mechanisms of strain I1P, especially its catalase enzyme, may confer UV resistance. This catalase was active in a wide range of temperatures (20–70 °C), showing optimal activity at 50 °C (at pH 7.0), a remarkable finding considering its psychrotolerant origin. In addition, this enzyme was thermostable, retaining around 60% of its activity after 6 h of incubation at 50 °C. The antioxidant defense systems of strain I1P, including its surprisingly thermoactive and thermostable catalase enzyme, make this microorganism a good source of biocompounds with potential biotechnological applications. Full article

During the next 15 years, around 200 km of tunnels and 68 new metro stations will be built around Paris to increase the capacity of the existing metro and the transport efficiency. The Société du Grand Paris—the public entity in charge of the design and the execution of this new network—is also highly concerned by the development and the use of renewable energy within this project, especially the integration of thermoactive metro stations in a smart energy system. This paper discusses some issues related to this strategy within the “Grand Paris Project”. The first part presents how smart technology could help to the integration of thermoactive metro stations into the urban energy system, while the second part addresses the following issues: assessment of the geothermal potential, estimate of the energy demand, ground investigations, thermal design, and finally system monitoring. The mechanical design is not considered in this paper. The paper shows the pertinence of the smart energy system for the integration of the thermoactive metro stations energy and the procedure for its implementation. Full article

A research project was developed in Spain to undertake some studies on the geothermal use of pile foundations (PITERM PROJECT). The experiment consists of a specifically designed, constructed and fully monitored geothermal precast pile driven at Polytechnic University of Valencia. An important distinctive feature of the developed pile was the fact that it was assembled from two identical sections connected with a specific joint, developed by Rodio-Kronsa. This allows the installation of much longer precast piles into the ground. The pile is under two types of loads: mechanical and thermal. The mechanical load was applied by means of a mechanical frame anchored to the ground and three additional anchors used to induce an active compressive force. The thermal load was produced by means of a thermal rig able to inject heat or extract heat from the pile at any desired programable heat injection/extraction rate. One of the features of this precast pile is its geometry, similar to a single U borehole heat exchanger (BHE) which is not common in thermoactive piles, usually equipped with probes attached to the armatures. In our study, we have characterized the thermal behaviour of the precast pile experimentally and simulated its temperature response by means of a TRNSYS model. This article describes part of a test series carried out where the mechanical and thermal behaviour of a pile subjected to thermal and mechanical loads simulating a real pile in a building was studied. Therefore, this publication has only focused on the thermal performance of the pile and its thermal modelling by computer. From this model, the thermal parameters of the soil–pile system have been extracted and compared with those of a single standard single U BHE. In essence, our assessment points to a quite similar thermal behaviour of the studied precast pile compared to a conventional single U borehole heat exchanger of the same length and equivalent diameter, while the installation costs of such elements would be substantially lower due to its double, structural and thermal, function. Full article

An innovative method to switch the wettability of a micropatterned polymeric surface by thermally induced shape memory effect is presented. For this purpose, first polycyclooctene (PCO) is crosslinked with dycumil peroxide (DCP) and its melting temperature, which corresponds with the switching transition temperature (Ttrans), is measured by Dynamic Mechanical Thermal Analysis (DMTA) in tension mode. Later, the shape memory behavior of the bulk material is analyzed under different experimental conditions employing a cyclic thermomechanical analysis (TMA). Finally, after creating shape memory micropillars by laser ablation of crosslinked thermo-active polycyclooctene (PCO), shape memory response and associated effect on water contact angle is analyzed. Thus, deformed micropillars cause lower contact angle on the surface from reduced roughness, but the original hydrophobicity is restored by thermally induced recovery of the original surface structure. Full article

We cloned the gene ACM61449 from anaerobic, thermophilic Caldicellulosiruptor bescii, and expressed it in Escherichia coli origami (DE3). After purification through thermal treatment and Ni-NTA agarose column extraction, we characterized the properties of the recombinant protein (CbPelA). The optimal temperature and pH of the protein were 72 °C and 5.2, respectively. CbPelA demonstrated high thermal-stability, with a half-life of 14 h at 70 °C. CbPelA also showed very high activity for polygalacturonic acid (PGA), and released monogalacturonic acid as its sole product. The V_max and K_m of CbPelA were 384.6 U·mg⁻¹ and 0.31 mg·mL⁻¹, respectively. CbPelA was also able to hydrolyze methylated pectin (48% and 10% relative activity on 20%–34% and 85% methylated pectin, respectively). The high thermo-activity and methylated pectin hydrolization activity of CbPelA suggest that it has potential applications in the food and textile industry. Full article