Energy Conversion Functions Research Articles

Transcriptomic analysis-based study on the response mechanism of juvenile golden cuttlefish (Sepia esculenta) to benzo[a]pyrene exposure

Benzo[a]pyrene (BaP), a polycyclic aromatic hydrocarbon from incomplete combustion, builds up in coastal regions through river runoff, atmospheric deposition, and coastal activities. BaP's lipophilicity and stability lead to persistent environmental impacts due to its resistance to degradation. The economically valuable golden cuttlefish, Sepia esculenta, often spawns and hatches in shallow waters, making it prone to BaP exposure. This study employs transcriptomic analysis to initially investigate juvenile golden cuttlefish's response to BaP. The results indicate that BaP exposure significantly affects various physiological and molecular functions of the juveniles, particularly affecting pathways related to immune and inflammatory responses, metabolic regulation, and nervous system functions. Functional enrichment and PPI network analyses identified key genes such as HSGALT-like, ASAH1-like, and GTL-like in the BaP response. These genes exhibited a suppressive trend during short-term exposure, indicating that BaP exposure may influence lipid metabolism, energy conversion, and digestive functions at the genetic level, which could further disrupt the overall physiological state and developmental processes of juvenile golden cuttlefish. The study offers novel insights into BaP's effects on juvenile golden cuttlefish and marine life, aiding marine ecosystem and biodiversity conservation.

Proof of Aerobically Autoxidized Self-Charge Concept Based on Single Catechol-Enriched Carbon Cathode Material

HighlightsAn air-breathing chemical self-charge concept of oxygen-enriched carbon cathode.The oxygen-enriched carbon material with abundant catechol groups.Rapid air-oxidation chemical self-charge of catechol groups.The self-charging concept has drawn considerable attention due to its excellent ability to achieve environmental energy harvesting, conversion and storage without an external power supply. However, most self-charging designs assembled by multiple energy harvesting, conversion and storage materials increase the energy transfer loss; the environmental energy supply is generally limited by climate and meteorological conditions, hindering the potential application of these self-powered devices to be available at all times. Based on aerobic autoxidation of catechol, which is similar to the electrochemical oxidation of the catechol groups on the carbon materials under an electrical charge, we proposed an air-breathing chemical self-charge concept based on the aerobic autoxidation of catechol groups on oxygen-enriched carbon materials to ortho-quinone groups. Energy harvesting, conversion and storage functions could be integrated on a single carbon material to avoid the energy transfer loss among the different materials. Moreover, the assembled Cu/oxygen-enriched carbon battery confirmed the feasibility of the air-oxidation self-charging/electrical discharging mechanism for potential applications. This air-breathing chemical self-charge concept could facilitate the exploration of high-efficiency sustainable air self-charging devices.

Populational genomic insights of Paraclostridium bifermentans as an emerging human pathogen.

Paraclostridium bifermentans (P.b) is an emerging human pathogen that is phylogenomically close to Paeniclostridium sordellii (P.s), while their populational genomic features and virulence capacity remain understudied. Here, we performed comparative genomic analyses of P.b and compared their pan-genomic features and virulence coding profiles to those of P.s. Our results revealed that P.b has a more plastic pangenome, a larger genome size, and a higher GC content than P.s. Interestingly, the P.b and P.s share similar core-genomic functions, but P.b encodes more functions in nutrient metabolism and energy conversion and fewer functions in host defense in their accessory-genomes. The P.b may initiate extracellular infection processes similar to those of P.s and Clostridium perfringens by encoding three toxin homologs (i.e., microbial collagenase, thiol-activated cytolysin, phospholipase C, which are involved in extracellular matrices degradation and membrane damaging) in their core-genomes. However, P.b is less toxic than the P.s by encoding fewer secretion toxins in the core-genome and fewer lethal toxins in the accessory-genome. Notably, P.b carries more toxins genes in their accessory-genomes, particularly those of plasmid origin. Moreover, three within-species and highly conserved plasmid groups, encoding virulence, gene acquisition, and adaptation, were carried by 25-33% of P.b strains and clustered by isolation source rather than geography. This study characterized the pan-genomic virulence features of P.b for the first time, and revealed that P. bifermentans is an emerging pathogen that can threaten human health in many aspects, emphasizing the importance of phenotypic and genomic characterizations of in situ clinical isolates.

Self-powered photoelectrochemical immunosensor with triple enhanced photoelectric response for sensitive detection of cTnI

A self-powered photoelectrochemical (PEC) immunosensor triple enhanced photoelectric response was proposed for the sensitive cardiac troponin (cTnI) detection. The self-powered PEC platform was constructed by sulfur indium copper hollow nanocage as a photocathode and hollow nanometer sphere heterojunction (In2S3 @CdIn2S4) as a photoanode, where the coulomb force of distinct photoelectrodes as the driving force effectively improves the photoelectric response without redox-mediator or external potential. In addition, the reverse transfer of photo-generated charge carriers increases the photoelectric response capacity due to the internal electric field effect in type II heterojunction. What is more exciting is that carefully designed hollow materials playing energy conversion function possess compelling properties. Given the advantages of multiple reflection effects in the cavity, thin-shell configuration and large surface, the designed hollow materials possessed a higher photon capture rate, a shorter-range transfer for photon-generated charges, and more active site points for the associated redox reactions, which facilitated the entire photoelectric response process. Based on the above strategies, the proposed PEC immunosensor achieved triple enhanced photoelectric response to present high sensitivity for detecting cTnI. The present study has gone some way to design nanomaterials with superior photoelectric activity, which paves a way for detecting other disease markers in high sensitivity.

Differential effect of water salinity levels on gas exchange, chlorophyll fluorescence and antioxidant compounds in ex vitro date palm plants

In this study, the response to salt stress was evaluated in ex vitro acclimated date palm plants, regenerated from in vitro culture multiplication. The plants, eighteen-month-old, were irrigated with 0 (control), 150, 300 or 450 mM NaCl solutions (high to very high-water salinity). Photosynthesis parameters and antioxidant compounds were determined at the end of the experiment in leaves. At 150 mM NaCl, net CO2 assimilation rate and internal CO2 concentration were not impaired; while transpiration and stomatal conductance decreased by 60 and 70%, respectively. By increasing salt concentrations, all gas exchanges parameters were decreased. Measurement of chlorophyll fluorescence and P700 redox state showed that PSII and PSI machineries were significantly enhanced under 150 mM NaCl, conditions. With the 300 mM NaCl, the PSI parameters remained unchanged compared to control, while some of the PSII parameters, such as NPQ and Y (NPQ), were increased. At 450 mM NaCl, photosystems functionality was light intensity (PAR) dependent. Only at low PAR, a significant increase of some PSI and PSII parameters was observed. At the contrary, with high PAR, most of the energy conversion functions were significantly reduced, especially those related to PSI, indicating that PSI was more susceptible for damage by salinity than PSII. To overcome high salinity stress, ex vitro date palm plants mobilized a cascade of physio-biochemical pathways including the antioxidant activity and proline biosynthesis. Overall, the salinity of irrigation water, and up to 150 mM, improves the physiological performance of ex vitro date palm plants, which manage to tolerate very high levels of this stress.

Partial selenium surface modulation of metal organic framework assisted cobalt sulfide hollow spheres for high performance bifunctional oxygen electrocatalysis and rechargeable zinc-air batteries

There is still a significant technological barrier in the development of high-performance electrocatalysts with synergistic unreliable functions and morphological integrity that improves reversible electrochemical activity, electrical conductivity, and mass transport properties. Metal-organic compound networks are envisioned as a defect-rich porous framework that provides mesoporous hollow carbon nanostructures composed primarily of an in situ-grown N-doped graphitic carbon matrix and embedded selenium-doped CoS2 hollow spheres as efficient, highly reactive, and long-lasting chemical energy conversion functions of the system. This method enables hitherto inaccessible synthesis approaches to produce a highly porous conductive network at the microscopic level while exposing rich unsaturated reactive sites at the atomic level without losing electrical or structural integrity. Because of their inherent increased electrochemical surface area, and electron transfer, the porous framework, doping motifs, and tailored structural defects provide outstanding bifunctional oxygen electrocatalysts for both oxygen reduction reaction (ORR) and oxygen evolution reactions (OER). Moreover, using this selenium-doped MOF CoS2 hollow spheres electrode as an air-cathode, a rechargeable zinc-air battery with excellent discharge-charge performance and mechanical stability is successfully constructed. This study provides a feasible and universal technique for constructing diverse functional interconnected metal-organic coordinated compounds that may be employed for a wide variety of energy storage, conversion (e.g., fuel cells and metal-air batteries), and environmental applications.

MoS2-decorated carbonized melamine foam/reduced graphene oxide network for constructing polyethylene-glycol-based multifunctional phase change materials toward multiple energy harvesting and microwave absorbing applications

The limited functions of traditional phase change materials (PCMs), such as thermal energy storage and temperature regulation, cannot fully satisfy the diversified requirements of various fields. Therefore, the development of multifunctional PCMs (MPCMs) is gradually gaining significant research attention. Herein, a functional MoS2-decorated carbonized melamine foam (CMF)/reduced graphene oxide (rGO) network (CMF/rGO/MoS2) is designed for developing MPCMs, in which CMF acts as a template, while rGO and MoS2 serve as functional fillers. Polyethylene glycol (PEG) is introduced into the network as a PCM using a vacuum‐assisted impregnation method. The obtained PEG@CMF/rGO/MoS2 composite has a high PEG content of 92.1 wt%, which contributes to its high melting and crystallization enthalpies of 169.3 and 165.9 J g−1, respectively. Simultaneously, the hybrid of rGO and MoS2 possesses good photon harvesting ability and electrically conductive properties, and endows the composite with light-to-thermal and electric-to-thermal energy conversion functions. Moreover, the synergistic effect of the three-dimensional porous structure and high dielectric loss capability of CMF/rGO/MoS2 render the composite a microwave absorbing material. As a result, the minimum reflection loss and maximum efficient bandwidth of PEG@CMF/rGO/MoS2 are −32.49 dB and 6.16 GHz at a thicknesses of 2.1 and 2.4 mm, respectively. Hence, our study provides an efficient strategy for developing MPCMs adaptable to different application requirements.

Molecular Imprinted BiVO4 Microswimmers for Selective Target Recognition and Removal.

Analogous to photosynthetic systems, photoactive semiconductor-based micro/nanoswimmers display biomimetic features that enable unique light harvesting and energy conversion functions and interactions with their surroundings. However, these artificial swimmers are usually non-selective and provide ineffective target recognition, resulting in poor surface analyte binding that affects the overall reactivity and motion efficiency. Here, the surface engineering of light-driven BiVO4 microswimmers by molecular imprinting polymerization is presented. After embedding surface recognition sites, the modified microswimmers can self-propel in a solution of a target molecule, without requiring toxic fuels, and degrade the target selectively in a pollutant mixture. These findings show that optimizing the design of semiconductor-based microswimmers with specific target recognition cavities on their surface is a promising strategy to achieve selective capture and degradation of organic pollutants, which is otherwise impossible because of the non-selective behavior of photogenerated reactive radicals. Moreover, this study provides a unique strategy to enhance the motion capabilities of single-component photocatalytic microswimmers in a specific chemical environment.

High thermal storage ability and photothermal conversion capacity phase change capsule with graphene oxide covalently grafted silica shell

Preparation of phase change materials with energy collection, conversion and storage functions is considered to be an important way to solve the energy shortage problem. Hence, a novel phase change capsule (EP@MGO) with photothermal conversion function was innovatively designed. In the process of preparing EP@MGO, the modified graphene oxide (MGO) layer was covalently anchored on the surface of the phase change capsule encapsulated by silica shell (EP) through Si-O-Si bonds, in which MGO was obtained by modifying GO nanosheets with isocyanate propyl triethoxysilane. The as-prepared EP@MGO microcapsule presents favorable latent heat storage capacity, with enthalpy of 139.8 J/g and high encapsulation efficiency of 83.6%. Besides, the thermal stability, leakage-proof property, durability, and thermal reliability of EP@MGO were enhanced significantly due to the physical protection effect provided by the SiO2-MGO double-layer shell. Moreover, the covalently MGO-grafted silica shell endows EP@MGO with high thermal conductivity (1.603 W/m·K), which improves its thermal management efficiency. More importantly, EP@MGO exhibits the potential ability to effectively utilize ultraviolet and visible light. In detail, the absorbance of EP@MGO increased by ∼192% in the ultraviolet and visible light region (200–800 nm), and the photothermal conversion efficiency under near infrared (NIR) region as high as 64.4%, which has negligible change (64.2%) even after 50 times heating-cooling cycle. Therefore, the phase change capsule EP@MGO provides a new idea for realizing efficient utilization of solar energy, and exhibits the application potential in biomedical treatment, smart textiles, and solar thermal collector.

Comparative assessment of piezoelectric and pyroelectric-hybrid energy conversion functions for flexible PVDF-based polymers

Comparative assessment of piezoelectric and pyroelectric-hybrid energy conversion functions for flexible PVDF-based polymers

A level‐set‐based shape optimization method for thermoelectric materials

AbstractA thermoelectric device is a useful device which directly converts thermal energy to electric energy and vice versa. Although this device has such energy conversion functions, the demands in the industries are limited because of the relatively low conversion performance. In order to enhance this performance, the thermal conductivity of thermoelectric material should be low. According to dramatic improvements of nano‐processing accuracy in recent decades, many thermoelectric materials have been developed with low thermal conductivities by utilizing a unique phenomenon of a nanoscale heat conduction which is called “temperature jump.” However, few structural optimization methods have been proposed for nanoscale thermoelectric materials since a conventional analysis method cannot be applied to a heat conduction problem in a nanostructure. On behalf of the Poisson's equation, we need to introduce a Boltzmann transport equation for describing a nanoscale heat conduction problem with a discontinuity effect on a material interface. The level set method has a potential for dealing with such a boundary condition in structural optimization. That is, material interfaces can be expressed by the iso‐surface of the level set function, and the boundary effects are imposed in the boundaries during the optimization procedures. In this paper, we propose a level‐set‐based shape optimization method for thermoelectric materials. First, an analysis method for a nanoscale heat conduction problem based on the Boltzmann transport equation is introduced. An objective functional is defined for obtaining a low thermal conductivity material. Then, based on an adjoint method, we derive the shape sensitivity, which enables us to consider the effects of the temperature jumps on the material interfaces. Next, a level‐set‐based shape optimization is applied to our optimization problem. Finally, as a validation of our proposed method, several numerical examples are computed.

Optimal Design and Analysis of Sector-Coupled Energy System in Northeast Japan

As for research on sector-coupled energy systems, few studies comprehensively deal with energy carriers and energy demand sectors. Moreover, few studies have analyzed energy conversion functions such as Power-to-Gas, Power-to-Heat, and Vehicle-to-Grid on the energy system performance. This study clarifies the required renewable resources and costs in the sector-coupled energy system and cost-optimal installed capacity and operation. We formulated an optimization model considering sector coupling and conducted a case study applying the model in the Tohoku region. As a result, due to sector coupling, the total primary energy supply (TPES) is expected to decrease, and system costs are expected to increase from 1.8 to 2.4 times the current level. System costs were minimized when maximizing the use of V2G by electric vehicles and district heating systems (DHS). From the hourly analysis, it becomes clear that the peak cut effect by Power-to-Heat and the peak shift effect by Vehicle-to-Grid result in leveling the output of electrolyzer and fuel synthesizer, which improves the capacity factor reducing capacity addition. Since a large amount of renewable energy is required to realize the designed energy system, it is necessary to reduce the energy demand mainly in the industrial sector. Besides, in order to reduce costs, it is required to utilize electric vehicles by V2G and provide policy support for district heating systems in Japan.

The Molecular Mechanisms of Mitochondrial Calcium Uptake by Calcium Uniporter

Mitochondria play a role as intracellular calcium stores as well as energy conversion functions. Excessive calcium accumulation in mitochondria induces cell death and induces diseases such as ischemia-reperfusion injury. Mitochondrial calcium uptake is considered to be mediated by calcium uniporters, which have attracted much attention as potential drug targets. Although calcium uniporter was shown to function as an ion channel, the molecular mechanisms have long been unclear. In this decade, the molecular composition of the calcium uniporter complex was discovered; the calcium uniporter consists of the 7 subunits. Each subunit has no structural similarity to other Ca ion channels; thus, the novel molecular mechanism of the Ca2+ uptake by calcium uniporter is of interest. Although calcium uniporter is conserved in human to warm, yeast lack mitochondrial calcium uptake activity. In the previous study, various subunits of mammalian calcium uniporter were expressed in the yeast mitochondria. As a result, although the expression of each subunit alone did not affect on the mitochondrial calcium uptake activity, the co-expression of mitochondrial calcium uniporter (MCU) and essential MCU regulator (EMRE) enabled to reconstitute calcium uptake activity in yeast mitochondria. This indicated that MCU and EMRE are key factors of the calcium uptake activity in mitochondria. This yeast reconstitution technique has also enabled us to perform detailed structure-function analysis of the MCU and EMRE. In this paper, we will discuss the molecular mechanism of Ca2+ uptake and the prospects for drug discovery.

The Molecular Mechanisms of Mitochondrial Calcium Ion Channel, Calcium Uniporter

Mitochondria play a role as intracellular calcium stores as well as energy conversion functions. Mitochondrial calcium uptake is mediated by mitochondrial calcium ion channel, “calcium uniporter”. In this decade, the molecular composition of the calcium uniporter complex was discovered; the calcium uniporter consists of the 7 subunits. Using the yeast reconstitution technique, we showed that MCU and EMRE are core subunits of the complex. The yeast reconstitution technique has also enabled us to perform detailed structure-function analysis of the MCU and EMRE. In this review, we will discuss the molecular mechanism of mitochondrial Ca2+ uptake.

Special Issue on Nonlinear Dynamics in Power Electronics-Enabled Energy Systems

Power electronics converters are indispensable parts of modern energy systems for achieving the required flexible energy conversion and transmission functions. The use of power electronics enables energy systems to fulfill critical roles in various utility applications, but at the same time necessitates imposition of stringent requirements for stability and safety purposes. Conventional linearized analysis methods usually assume that the system under study operates at a fixed point with a small range of variation. However, the dynamical behavior of power electronics systems often invalidates the small-signal assumption due to the nonlinear characteristics of power electronics devices and operations, especially when the system exhibits inevitable disturbances such as the source/load power fluctuations, device/transmission line faults, etc. This Special Issue comprises 18 papers presenting recent research trends and cutting-edge research results in the field of nonlinear dynamics in power electronics-enabled energy systems.

Influence of Flame Retardants on LLDPE‐Date Pit Fiber Composites: Thermal Degradation and Tensile Properties

AbstractLinear low density polyethylene (LLDPE)‐date pit composites incorporated with different flame retardants were synthesized by extrusion and casted into shape by injection moulding. Several additive type flame retardants viz. Ammonium polyphosphate (APP), Melamine phosphate (MP), Ammonium dihydrogen orthophosphate (ADOP), Diammonium hydrogen phosphate (DAHP) were added to enhance the flame retarding behaviour of composites. The thermal analysis and mechanical properties of composites have also been investigated. Thermogravimetric analysis (TGA) revealed a two step degradation mechanism of all the blends. The kinetic parameters such as activation energy and differential conversion function f(ɑ) were evaluated using three different non isothermal methods based on the iso conversional plots: Friedman (FM), Ozawa‐Flynn‐Wall (OFW) and Coats‐Redfern (Modified). The average value of activation energy of thermal degradation of blends evaluated using Friedman method; was used to depict the actual mechanism of degradation by fabricating the Criado's master plot. Addition of any kind of flame retardant led to an improvement in both tensile as well as flexural strength of composites. According to the results of Limiting Oxygen Index (LOI) and UL‐94 testing, addition of APP led to the significant improvement in the flame retardancy of LLDPE composites.

Robust Optimization Model for Energy Purchase and Sale of Electric–Gas Interconnection System in Multi-Energy Market

With the increasing coupling of the power system and the natural gas system, the electric–gas interconnection system has become a typical form of comprehensive energy utilization. Through the energy conversion function of the coupling unit, the system can flexibly participate in the bidding for purchasing and selling energy in a power market and a natural gas market on the premise of meeting the internal demand of multiple loads. To solve the internal coordination and optimization problem and the external flexible bidding problem in the multi-energy market, this paper proposes a robust optimization model of energy purchase and sale for the electric–gas interconnection system in a multi-energy market. Firstly, the basic structure of the electric–gas interconnection system is introduced, and the steady-state model of energy flow in the system is built based on the energy hub model. Secondly, considering the uncertainty of energy prices and the output power of renewable energy units in the system, a bidding model for energy purchase and sale of the electric–gas interconnection system in multi-energy market based on the idea of robust optimization is constructed in the framework of the Nordic energy market. Finally, empirical analysis based on the actual data is carried out, and the results prove the validity and superiority of the model. In this paper, aiming at the uncertainty of energy price, a large number of scenes are generated by Latin hypercube sampling (LHS), and then a k-means algorithm is used to reduce the scenes, so as to simulate typical scenes. Aiming at the uncertainty of the output power of the renewable energy unit in the system, a cardinal uncertainty set is used to control deviation between the actual output power and predicted output power, so that the overall robustness of the model can be controlled. The proposed model can make decision-making independent of the accurate probability distribution of uncertainty factors, and is suitable for complex multi energy systems. Meanwhile, the model possesses excellent robustness, which can effectively reduce the risk of bidding loss in the process of energy purchase and sale.

A constitutive model for rock based on energy dissipation and transformation principles

The study on constitutive relations is of great significance to the understanding of the complex mechanical properties and failure criteria of rock. The establishment of a scientific rock constitutive model can provide theoretical support for engineering safety and geological disaster prevention. From the view point of energy, a new rock constitutive model under triaxial compression was developed by connecting the law of energy transformation with the mechanical properties of rock in the paper. First, the concepts of elastic energy conversion rate and elastic energy conversion function were proposed to describe principles of energy dissipation and energy transformation in the whole stress-strain process of rock. And, a mathematical description was made of the work of external force transforming into elastic energy. Second, assumptions were proposed to describe the evolution laws of some important mechanical parameters. Finally, the quasi-static constitutive model for rock under triaxial compression based on conservation of energy was established, combining theories of damage mechanics and thermodynamic, and the fitted results of this constitutive model were compared to experimental data of sandstone under triaxial cyclic loading tests. The rationality of the constitutive model for rock was proved by describing the whole stress-strain process of triaxial compression under different confining pressures. And, the model can describe the initial compaction stage and residual stress of stress-strain curve, which can reflect the nonlinear characteristics of rock.

Melanin: A Greener Route To Enhance Energy Storage under Solar Light.

The development of technologies integrating solar energy conversion and energy storage functions is critical for limiting the anthropogenic effects on climate change and preventing possible energy shortages related to the increase of the world population. In our work, we explored the possibility to integrate the conversion and storage functions within the same multifunctional biosourced material. We identified the redox-active, quinone-based, melanin pigment, featuring a broadband absorption in the UV–vis region, as the ideal candidate for such an exploration. Electrodes of melanin on carbon paper were investigated for their morphological, optical, and voltammetric characteristics prior to being assembled into symmetric supercapacitors operating in aqueous electrolytes. We observed that, under solar light, the capacity and capacitance of melanin electrodes significantly increase with respect to the dark conditions (by 22 and 39%, respectively). Once in a supercapacitor configuration, besides featuring a Coulombic efficiency close to 100% after 5000 cycles, the capacitance and capacity of the electrodes, rated by the initial values, improve after prolonged illumination, as it is the case for the energy and power density.

Piecewise linear bounding of univariate nonlinear functions and resulting mixed integer linear programming-based solution methods

Various optimization problems result from the introduction of nonlinear terms into combinatorial optimization problems. In the context of energy optimization for example, energy sources can have very different characteristics in terms of power range and energy demand/cost function, also known as efficiency function or energy conversion function. Introducing these energy sources characteristics in combinatorial optimization problems, such as energy resource allocation problems or energy-consuming activity scheduling problems may result into mixed integer nonlinear problems neither convex nor concave. Approximations via piecewise linear functions have been proposed in the literature. Non-convex optimization models and heuristics exist to compute optimal breakpoint positions under a bounded absolute error-tolerance. We present an alternative solution method based on the upper and lower bounding of nonlinear terms using non necessarily continuous piecewise linear functions with a relative epsilon-tolerance. Conditions under which such approach yields a pair of mixed integer linear programs with a performance guarantee are analyzed. Models and algorithms to compute the non necessarily continuous piecewise linear functions with absolute and relative tolerances are also presented. Computational evaluations performed on energy optimization problems for hybrid electric vehicles show the efficiency of the method with regards to the state of the art.