Decrease In Transfer Efficiency Research Articles

Heat transfer efficiency of thermoelastic shaped phase change materials enhanced by pressure

As the melt front gradually moves away from the heat source during the heat transfer process, phase change materials (PCMs) inevitably cause the heat transfer efficiency to decrease with heat transfer time, especially for a shaped PCM (SPCM). In this study, it is proposed to compress the SPCM phase-changed region by pressure to reduce the thermal resistance between the heat source and the phase transition interface, thus slowing down the rate of heat transfer efficiency decrease. We established a one-dimensional semi-infinite compression heat transfer theoretical model and prepared a thermoelastic SPCM (TESPCM) for compression heat transfer experiments, which verified the reliability of the theoretical model. Experimental demonstrate that the pressure enhancement contributes to the heat transfer efficiency and becomes more pronounced with heat transfer time. The pressure-enhanced heat transfer was analyzed by the theoretical model with the following conclusions: pressure enhancement not only improves the latent heat utilization, heat transfer cut-off time, and maximum tolerable heat flux of TESPCM but also increases the specific energy and specific power of TESPCM. The effect of pressure on heat transfer efficiency tends to accelerate with increasing compression. Furthermore, the improvement of heat transfer by pressure enhancement becomes more significant with the increase of thermal conductivity, but the effect of latent heat on temperature control decreases with the increase of compression.

Constructing Protein-Scaffolded Multienzyme Assembly Enhances the Coupling Efficiency of the P450 System for Efficient Daidzein Biosynthesis from (2S)-Naringenin.

Daidzein is a major isoflavone compound with an immense pharmaceutical value. This study applied a novel P450 CYP82D26 which can biosynthesize daidzein from (2S)-naringenin. However, the recombinant P450 systems often suffer from low coupling efficiency, leading to an electron transfer efficiency decrease and harmful reactive oxygen species release, thereby compromising their stability and catalytic efficiency. To address these challenges, the SH3-GBD-PDZ (SGP) protein scaffold was applied to assemble a multienzyme system comprising CYP82D26, P450 reductase, and NADP+-dependent aldehyde reductase in desired stoichiometric ratios. Results showed that the coupling efficiency of the P450 system was significantly increased, primarily attributed to the channeling effect of NADPH resulting from the proximity of tethered enzymes and the electrostatic interactions between NADPH and SGP. Assembling this SGP-scaffolded assembly system in Escherichia coli yielded a titer of 240.5 mg/L daidzein with an 86% (2S)-naringenin conversion rate, which showed a 9-fold increase over the free enzymes of the P450 system. These results underscore the potential application of the SGP-scaffolded multienzyme system in enhancing the coupling and catalytic efficiency of the P450 system.

Markov State Study of Electrostatic Channeling within the Tricarboxylic Acid Cycle Supercomplex.

The high efficiency of cascade reactions in supramolecular enzyme nanoassemblies, known as metabolons, has attracted substantial attention in various fields ranging from fundamental biochemistry and molecular biology to recent applications in biofuel cells, biosensors, and chemical synthesis. One reason for the high efficiency of metabolons is the structures formed by sequential enzymes that allow the direct transport of intermediates between consecutive active sites. The supercomplex of malate dehydrogenase (MDH) and citrate synthase (CS) is an ideal example of the controlled transport of intermediates via electrostatic channeling. Here, using a combination of molecular dynamics (MD) simulations and a Markov state model (MSM), we examined the transport process of the intermediate oxaloacetate (OAA) from MDH to CS. The MSM enables the identification of the dominant transport pathways of OAA from MDH to CS. Analysis of all pathways using a hub score approach reveals a small set of residues that control OAA transport. This set includes an arginine residue previously identified experimentally. MSM analysis of a mutated complex, where the identified arginine is replaced by alanine, led to a 2-fold decrease in transfer efficiency, also consistent with experimental results. This work provides a molecular-level understanding of the electrostatic channeling mechanism and will enable the further design of catalytic nanostructures utilizing electrostatic channeling.

On the Non-idealities of a Capacitive Link for Wireless Power Transfer to Biomedical Implants.

This paper studies the performance of a resonant capacitive wireless power transfer (C-WPT) link for biomedical implants in the presence of non-idealities. The study emphasizes on finding an accurate electrical model of a practical C-WPT link, which can be used to investigate the performance of the link under different practical/non-ideal scenarios. A sound knowledge about these non-idealities is crucial for device optimization. For the first time, a circuit model has been presented and analyzed, which is applicable to a practical C-WPT link undergoing plate mismatch, flexion, tissue contraction, and stretching. Our model considers the finite conductivity of the body tissue and fringe fields formed by capacitor plates. Analytical and HFSSTM simulation results have been presented for different non-idealities, and are in good agreement. Additionally, we show a procedure to interpolate non-ideal case results. The study shows that plate misalignment (causing reduction in parallel plate overlap area) and skin tissue contraction (while muscle grows) are the most detrimental individual factors to the link performance. We recorded ∼32% and ∼14% power transfer efficiency decrease due to these two worst-case scenarios, respectively for a C-WPT link comprising of two pairs of 400 mm2 parallel plates (12 cm edge-to-edge separation) coated with 63.5 µm thick Kapton layer and aligned around a 3 mm tissue at 20 MHz.

Compensation for Lateral Misalignment in Litz Wire Based on Multilayer Coil Technology.

This study applies a multilayer coil technology that can compensate for a decrease in transfer efficiency due to a lateral misalignment in a practical 100 kHz-band wireless power transfer system and validates its effect on the efficiency of compensation. The effectiveness is investigated using coils fabricated with Litz wires. Three-turn rectangular assistant coils 22.4 × 45.3 mm2 in size were stacked on a five-turn circular primary coil with a diameter of 45.3 mm in a 2 × 1 array. Transfer efficiency between two such coils was measured by producing lateral misalignment, while maintaining the vertical distance between the Tx and Rx coils at 7 mm. The experimental results showed that the transfer efficiency was compensated by approximately 46.1%P maximum in a misalignment state of 30 mm, which corresponded to 67% of the maximum size of the coil, compared to the transfer efficiency of the structure, in which the multilayer coil was not applied. Furthermore, transfer efficiency was compensated by 37.6%P, even in an asymmetric system in which the multilayer structure was applied only to the Tx coil, thereby confirming an excellent multilayer coil technology effect on compensation for lateral misalignment in practical cases.

Climate-induced decrease in biomass flow in marine food webs may severely affect predators and ecosystem production.

Climate change impacts on marine life in the world ocean are expected to accelerate over the 21st century, affecting the structure and functioning of food webs. We analyzed a key aspect of this issue, focusing on the impact of changes in biomass flow within marine food webs and the resulting effects on ecosystem biomass and production. We used a modeling framework based on a parsimonious quasi-physical representation of biomass flow through the food web, to explore the future of marine consumer biomass and production at the global scale over the 21st century. Biomass flow is determined by three climate-related factors: primary production entering the food web, trophic transfer efficiency describing losses in biomass transfers from one trophic level (TL) to the next, and flow kinetic measuring the speed of biomass transfers within the food web. Using climate projections of three earth system models, we calculated biomass and production at each TL on a 1° latitude×1° longitude grid of the global ocean under two greenhouse gas emission scenarios. We show that the alterations of the trophic functioning of marine ecosystems, mainly driven by faster and less efficient biomass transfers and decreasing primary production, would lead to a projected decline in total consumer biomass by 18.5% by 2090-2099 relative to 1986-2005 under the "no mitigation policy" scenario. The projected decrease in transfer efficiency is expected to amplify impacts at higher TLs, leading to a 21.3% decrease in abundance of predators and thus to a change in the overall trophic structure of marine ecosystems. Marine animal production is also projected to decline but to a lesser extent than biomass. Our study highlights that the temporal and spatial projected changes in biomass and production would imply direct repercussions on the future of world fisheries and beyond all services provided by Ocean.

Enhancing the Stability of Medium Range and Misalignment Wireless Power Transfer System by Negative Magnetic Metamaterials.

The misalignment of the resonant coils in wireless power transfer (WPT) systems causes a sharp decrease in transfer efficiency. This paper presents a method which improves the misalignment tolerance of WPT systems. Based on electromagnetic simulations, the structural unit parameters of the electromagnetic material were extracted, and an experimental prototype of a four-coil WPT system was built. The influence of electromagnetic metamaterials on the WPT system under the conditions of lateral misalignment and angular offset was investigated. Experiments showed that the transfer efficiency of the system could be maintained above 45% when the transfer distance of the WPT system with electromagnetic metamaterials was 1 m and the resonant coils were shifted laterally within one coil diameter. Furthermore, the system transfer efficiency could be stabilized by more than 40% within an angle variation range of 70 degrees. Under the same conditions, the transfer efficiency of a system without electromagnetic metamaterials was as low as 30% when lateral migration occurred, and less than 25% when the angle changed. This comparison shows that the stability of the WPT system loaded with electromagnetic metamaterials was significantly enhanced.

Maximum efficiency tracking control of underwater wireless power transfer system using artificial neural networks

In the underwater wireless power transfer system for the marine vehicle, the system transfer efficiency is influenced by factors including coupling state and load condition. To solve the problem of transfer efficiency decrease caused by the dynamic changes of coupling coefficient and load conditions, a maximum efficiency tracking method based on the dynamic identification of optimal output voltage and coupling coefficient is proposed. Moreover, the approximation characteristic to the nonlinear function of artificial neural networks is used to dynamically adjust the output voltage of DC/DC converter, and the deviation between the output voltage and optimal voltage can be kept within the allowable error range leading to maximum efficiency tracking. The experimental results show that the control method can calculate the optimal output voltage correctly, adjust the output voltage quickly and accurately, and achieve the maximum efficiency of the wireless power transfer system when the coupling coefficient and load conditions change dynamically.

Prior exposure of agriculture cephalosporin ceftiofur impaired conjugation of blaCTX-M-65 gene-bearing plasmid in Salmonella Saintpaul.

Although a link between agricultural cephalosporin use and resistance in Salmonella has been demonstrated with the drug ceftiofur, the underlying mechanism of the correlation is unclear. This study investigated the impact of ceftiofur exposure in S. Saintpaul on ceftriaxone resistance, the gene expression and the conjugative transfer of the blaCTX-M-65 gene. Prior ceftiofur exposure caused a twofold increase in MIC from 1024 to 2048µgml-1 towards ceftriaxone and increased the enzymatic activity of BlaCTX-M-65 2·2 folds from 3·46 to 7·67nmol nitrocefin hydrolysed min-1 . A threefold upregulation in gene expression of the blaCTX-M-65 gene was also observed. Donors exposed to ceftiofur subsequently demonstrated a 2·5-fold decrease in transfer efficiency. Prior exposure of S. Saintpaul to ceftiofur led to increased phenotypic resistance towards ceftriaxone while its ability to spread the cephalosporin resistance through conjugation, conversely, was impaired. Findings from this study shed light on one possible mechanism in which agricultural cephalosporin exposure in Salmonella may subsequently impact clinical treatment. The finding that cephalosporin exposure in donors may hinder the subsequent spread of resistance instead of aiding it up was counter-intuitive.

Design and optimization of hybrid resonant loops for efficient wireless power transfer

SummaryFrequency splitting, caused by magnetic overcoupling, is a great challenge in resonant wireless power transfer, which leads to decrease of transfer efficiency. In this paper, to avoid the frequency splitting, a new design of hybrid resonant loops with an inner coil positioned in the transmitter is proposed for efficient power transfer. It is shown to suppress dramatic variation of mutual inductance when the distance between transmitter and receiver decreases. Analytical expressions of the mutual inductance and the transfer efficiency for the proposed resonant wireless power transfer system are calculated. To obtain a relatively uniform mutual inductance with respect to the distance, the proposed resonant loops are optimized. Simulation and experiments are also performed to validate the effectiveness of the proposed resonant loops in eliminating the frequency splitting. The transfer efficiency remains higher than 80% when the transfer distance decreases below a critical value where frequency splitting occurs for conventional resonant loops. Furthermore, lateral and angular misalignments between the resonant loops are also considered and investigated. The results indicate that the proposed resonant loops are also applicable in suppressing the frequency splitting even in case of misalignments.

An NFC on Two-Coil WPT Link for Implantable Biomedical Sensors under Ultra-Weak Coupling.

The inductive link is widely used in implantable biomedical sensor systems to achieve near-field communication (NFC) and wireless power transfer (WPT). However, it is tough to achieve reliable NFC on an inductive WPT link when the coupling coefficient is ultra-low (0.01 typically), since the NFC signal (especially for the uplink from the in-body part to the out-body part) could be too weak to be detected. Traditional load shift keying (LSK) requires strong coupling to pass the load modulation information to the power source. Instead of using LSK, we propose a dual-carrier NFC scheme for the weak-coupled inductive link; using binary phase shift keying (BPSK) modulation, its downlink data are modulated on the power carrier (2 MHz), while its uplink data are modulated on another carrier (125 kHz). The two carriers are transferred through the same coil pair. To overcome the strong interference of the power carrier, dedicated circuits are introduced. In addition, to minimize the power transfer efficiency decrease caused by adding NFC, we optimize the inductive link circuit parameters and approach the receiver sensitivity limit. In the prototype experiments, even though the coupling coefficient is as low as 0.008, the in-body transmitter costs only 0.61 mW power carrying 10 kbps of data, and achieves a 1 × 10 bit error rate under the strong interference of WPT. This dual-carrier NFC scheme could be useful for small-sized implantable biomedical sensor applications.

2 상 유동 및 물질전달 특성에 미치는 오리피스 노즐형상과 소요동력의 영향

Abstract : It is necessary to investigate the input power as well as the mass transfer characteristics of the aeration process in order to improve the energy efficiency of an aerobic water treatment. The objective of this study is to experimentally investigate the effect of orifice nozzle design and input power on the flow and mass transfer characteristics of a vertical two-phase flow. The mass ratio, input power, volumetric mass transfer coefficient, and mass transfer efficiency were calculated using the measured data. It was found that as the input power increases the volumetric mass transfer coefficient increases, while the mass ratio and mass transfer efficiency decrease. The mass ratio, volumetric mass transfer coefficient, and mass transfer efficiency were higher for the orifice configuration with a smaller orifice nozzle area ratio. An empirical correlation was proposed to estimate the effect of mass ratio, input power, and Froude number on the volumetric mass transfer coefficient.

Extending DNA‐Based Molecular Photonic Wires with Homogeneous Förster Resonance Energy Transfer

Molecular photonic wires (MPWs) precisely position dyes using structural DNA methodologies where they exploit Förster resonance energy transfer (FRET) to direct photonic energy over nm distances with potential applications in light harvesting, biosensing, and molecular electronics. Although versatile, the number of donor–acceptor dye pairs available and the downhill nature of FRET combine to limit the size and efficiency of current MPWs. HomoFRET between identical dyes should provide zero energy loss but at the cost of random transfer directionality. Here, it has been investigated what HomoFRET has to offer as a means to extend MPWs. Steady‐state‐, lifetime‐, and fluorescence anisotropy measurements along with mathematical models are utilized to experimentally examine various 3‐, 4‐, and 5‐dye MPW constructs containing from 1 to 6 HomoFRET repeat sections. Results show that HomoFRET can be extended up to 6 repeat dyes/5 steps with only a ≈55% energy transfer efficiency decrease while doubling the longest MPW length to a remarkable 30 nm. Critically, analogous constructs lacking the HomoFRET portion are unable to deliver any energy over the same lengths. Even with nondirectionality, the introduction of a repeated‐optimized HomoFRET transfer dye is preferable compared to additional less efficient dye species. HomoFRET further provides the benefit of having a higher energy output.

Inductor array for minimising transfer efficiency decrease of wireless power transmission components at misalignment

A secondary coil design is reported for the stable transmission of wireless power in a misalignment situation. A coil array is applied to a secondary coil instead of typical single coil. When a misalignment occurs, the misalignment distance between an individual coil in the array and the primary coil is decreased relatively. Therefore, the sudden reduction in the inductive wireless power transmission (WPT) efficiency is mitigated. When the fabricated coil array transmits power, the maximum WPT efficiency improves by 56.45% compared with the typical single coil. The frequency band of the proposed array is wider, and this system can stably transmit power.

Carotenoid Excited-State Properties in Photosynthetic Purple Bacterial Reaction Centers: Effects of the Protein Environment

Carotenoid excited-state properties are characterized and compared in reaction centers (RCs) of wild-type (WT) Rhodobacter (Rb.) sphaeroides , and a mutant VR(L157), in which the near-infrared absorbance band associated with the primary electron donor, P, is missing. Energy transfer from the carotenoid (spheroidenone) S(2) and relaxed S(1) excited states to an adjacent monomeric-bacteriochlorophyll is unchanged between WT and the mutant RC samples. However, two other excited states, including a vibrationally hot S(1) state and a state referred to as S*, have distinct properties in the two RCs. The lifetime of the hot S(1) state is significantly shortened in the P-less mutant compared to WT RCs (450 fs vs 800 fs, respectively), and there is a nearly 2-fold decrease in the efficiency of energy transfer from the carotenoid to bacteriochlorophyll in the P-less mutant relative to WT RCs. The fact that both the observed hot S(1) excited state lifetime and the energy transfer efficiency decrease in the mutant implies that the intrinsic lifetime of the hot S(1) state in the P-less mutant has decreased. Interestingly, the S* state is observed only in the P-less mutant, and it is not present in the WT. The change in the hot S(1) lifetime between WT and mutant RCs, and the formation of the S* state only in the mutant, suggests that the carotenoid binding pocket in the P-less mutant is substantially altered. The excited-state behavior of spheroidene in WT RCs isolated from anaerobically grown cells was also characterized and compared with previous studies of spheroidene in the light-harvesting complex II (LH2) from Rb. sphaeroides . Differences in the photophysical properties of spheroidene between WT RCs and LH2 parallel those observed for spheroidenone between WT and VR(L157) mutant RCs. On the basis of the structural information available for both RCs and LH2, it appears that the hot S(1) state and the S* state are sensitive to the structural constraints imposed by protein-carotenoid interactions. Finally, in the VR(L157) mutant, it is possible to directly observe the carotenoid triplet state, likely formed via quenching of the bacteriochlorophyll triplet state. This provides direct experimental evidence for triplet energy transfer to the carotenoid, a process that is integral to the photoprotective role of carotenoids in bacterial RCs.

Evaluation of frequency characteristics of transformer with bulk HTSs shielding

In a conventional transformer, secondary voltage and power transfer efficiency decrease when the magnetic flux leaks from the magnetic circuit of the transformer and the leakage reactance increases. Magnetic shielding of the magnetic circuit of the transformer with plural bulk high temperature superconductors (HTSs) was evaluated as a method of improving transformer characteristics. In our previous research, transformer characteristics were evaluated with a constant secondary load at each frequency. In this research, appropriate secondary loads were connected for each frequency to evaluate the characteristics in conformity with the actual transformer operation. The frequency characteristics of transformers with and without bulk HTSs shielding were evaluated with a constant magnetic flux density in the magnetic circuit. An increase in the secondary voltage and power transfer efficiency was confirmed for a transformer with bulk HTSs shielding at all frequencies, as dispersion of the magnetic flux was controlled by bulk HTSs shielding.

Energy Transfer by a Hopping Mechanism in Dinuclear IrIII/RuII Complexes: A Molecular Wire?

The synthesis and electrochemical and photophysical properties of a series of heterodinuclear ruthenium-iridium complexes linked by a modular para-phenylene bridge [Ir-ph(n)-Ru]3+ (Ir=Ir(ppyFF)2bpy, Ru=Ru(bpy)3, ppyFF=2-(2,4-difluorophenyl)pyridine), bpy=2,2'-bipyridine, ph=phenylene, n=2, 3, 4, 5) are reported. The use of a high-energy iridium complex, which can act as an energy donor when coupled to the lower energy ruthenium-based component, allows the investigation of photoinduced energy transfer from the excited iridium-centre to the ruthenium fragment (energy acceptor). The rate constants of the energy-transfer processes are determined by time-resolved emission and sub-picosecond transient absorption spectroscopy. Interestingly, there is almost no decrease in transfer efficiency or rates as the length between the two chromophores (number of spacers) is increased. This "molecular wire" behavior indicates the dominance of the incoherent hopping mechanism, allowing a very fast energy transfer over long distances (with n = 5 the metal-to-metal distance is estimated to be 32.5 Angstrom). This is the first case in which such behavior is observed for metal complexes, and could lead to new development in molecular electronics.

Proposal of Transformer Using Magnetic Shielding With Bulk High<tex>$T_rm c$</tex>Superconductors

As for a general transformer using a ferromagnetic core, the magnetic flux may leak by using the high frequency and the overload. When the magnetic flux leaks from the core, the secondary voltage and its power transfer efficiency decrease. Bulk high T/sub c/ superconductors (HTS's) with the high critical current density have the strong magnetic shielding characteristic at the static magnetic field and the AC magnetic field. Thus, we examined to surround a magnetic circuit of a transformer with bulk HTS's. From this research, when the magnetic circuit of the transformer was surrounded with plural HTS's, it was confirmed that the secondary voltage and the power transfer efficiency of the transformer increased especially in the high frequency range.

Clarifying Behavior of Prallethrin Evaporated from an Electric Vaporizer on the Floor and Estimating Associated Dermal Exposure

The behavior of prallethrin evaporated from an electric vaporizer was investigated through three experiments to determine: 1) distribution of residue levels on the floor, 2) floor levels during prolonged daily evaporation and 3) amount of residue transferable from the floor. Results of the third experiment suggest a regular decrease of transfer efficiency denoted by the function of time (t)−0.5. From the measured values, dermal exposure was estimated for Japanese sub-groups using a new methodology based on the US EPA procedure, taking into account periodic application, a body-specific transfer factor, the transition rate through clothes, and the ratio of bodily deposition to floor deposition. © Pesticide Science Society of Japan

Molecular basis for low temperature compartment formation by transitional endoplasmic reticulum of rat liver

The molecular basis for temperature compartment formation was investigated using a cell-free system from rat liver. The donor was from liver slices prelabeled with [ 3H]acetate. Unlabeled Golgi apparatus membranes were immobilized on nitrocellulose as the acceptor. When transfer was determined as a function of temperature, a transition in transfer activity was observed at low temperatures (≤ 20°C) similar to that seen in vivo. The decrease in transfer efficiency correlated with a decrease in phosphatidylethanolamine and phosphatidylserine content of the transition vesicles formed. By adding lipid mixtures enriched in these lipids to the vesicles, their ability to fuse with the cis Golgi apparatus was reconstituted. These findings provide evidence for a role for lipids in low temperature compartment formation.