Low Energy Loss Research Articles

A novel Fontan Y-graft for interrupted inferior vena cava and azygos continuation.

OBJECTIVESTo evaluate the hemodynamicdynamic advantage of a new Fontan surgical template that is intended for complex single-ventricle patients with interrupted inferior vena cava-azygos and hemi-azygos continuation. The new technique has emerged from a comprehensive pre-surgical simulation campaign conducted to facilitate a balanced hepatic flow and somatic Fontan pathway growth after Kawashima procedure.METHODSFor 9 patients, aged 2 to18 years, majority having poor preoperative oxygen saturation, a pre-surgical computational fluid dynamics customization is conducted. Both the traditional Fontan pathways and the proposed novel Y-graft templates are considered. Numerical model was validated against in vivo phase-contrast magnetic resonance imaging data and in vitro experiments.RESULTSThe proposed template is selected and executed for 6 out of the 9 patients based on its predicted superior hemodynamic performance. Pre-surgical simulations performed for this cohort indicated that flow from the hepatic veins (HEP) do not reach to the desired lung. The novel Y-graft template, customized via a right- or left-sided displacement of the total cavopulmonary connection anastomosis location resulted a drastic increase in HEP flow to the desired lung. Orientation of HEP to azygos direct shunt is found to be important as it can alter the flow pattern from 38% in the caudally located direct shunt to 3% in the cranial configuration with significantly reversed flow. The postoperative measurements prove that oxygen saturation increased significantly (P-value = 0.00009) to normal levels in 1 year follow-up.CONCLUSIONSThe new Y-graft template, if customized for the individual patient, is a viable alternative to the traditional surgical pathways. This template addresses the competing hemodynamic design factors of low physiological venous pressure, high postoperative oxygen saturation, low energy loss and balanced hepatic growth factor distribution possibly assuring adequate lung development.Date and number of IRB approval25 October 2019, 280011928-604.01.01.

Strengthening the Intermolecular Interaction of Prototypical Semicrystalline Conjugated Polymer Enables Improved Photocurrent Generation at the Heterojunction.

The intra and intermolecular interactions (J- and H-type aggregation) in the conjugated polymer films are found to readily facilitate the electron and hole transport, respectively. However, how those different aggregation types influence the photocurrent generation at the heterojunction is still mysterious, especially for the newly developed semicrystalline conjugated polymers. Here, the prototypical copolymer PM6 is used to tune the relative content of aggregation types with various halogen-free processing solvents. Various measurements reveal that the toluene-processed PM6 film exhibits the increased H-aggregates and crystallinity in the π-π stacking direction compared to its o-xylene- and trimethylbenzene (TMB)-processed counterparts. This is partly resulted from the weak steric effect and good solubility in the PM6 solution prepared with toluene, which strengthens the intermolecular interaction of adjacent polymer segments. After analyzing the photovoltaic properties of PM6/Y6 bilayer devices, the faster charge carrier transport, smaller charge recombination, lower energy losses, and interfacial energetic disorder can be observed in the toluene-processed device, leading to the synergistically improved short-circuit current density (JSC ) and open-circuit voltage (VOC ). These findings indicate the control of the molecular packing structure in terms of aggregation types is a powerful strategy to promote the photocurrent generation process at the conjugated polymer-based heterojunction.

Charge Utilization Efficiency and Side Reactions in the Electrochemical Mechanical Polishing of 4H-SiC (0001)

Slurryless electrochemical mechanical polishing (ECMP) is very effective in the polishing of silicon carbide (SiC) wafers. To achieve a high material removal rate (MRR) of SiC wafer using ECMP with low electrical energy loss, charge utilization efficiency in the anodic oxidation of the SiC surface was investigated and the underlying mechanism was clarified by modeling the anodic oxidation system of SiC in 1 wt% NaCl aqueous solution. The charge utilization efficiency in the anodic oxidation of SiC was found to be constant when the current density was less than 20 mA cm−2 and significantly decreased when the current density was greater than 30 mA cm−2, resulting in a significant reduction in the MRR. Modeling of the anodic oxidation system indicates that the charge utilization efficiency depended on the potential applied on the SiC surface: the oxidation of SiC occupied the dominant position in the anodizing system when the potential is lower than 25 V vs Ag∣AgCl, charge utilization efficiency greatly decreased when the applied potential was greater than 25 V owing to the occurrence of oxidations of the H2O and Cl−. This research provides both a theoretical and practical foundation for using ECMP to polish SiC wafers.

Evaluation of trashrack replacement design for malalo intake of singkarak hydro power plant in west Sumatera

Singkarak hydro power plant (SHPP) with the capacity of 175 MW provide essential supply to Sumatera Interconnection System thus reliable and efficient operation of the hydro power plant component must be maintained. With the damaged experienced by the trash rack during Padang earthquake, the operation of the power plant was disturbed and replacement of trash rack need to be executed. This study evaluate the modification of trash rack replacement in terms of head loss, potential energy and revenue losses. This simple evaluation finds that the replacement design gives lower head loss which translated to lower energy and revenue losses. The potential energy and revenue losses also increase exponentially with the increase of trash rack blockage. This result amplify the importance of trash rack design and cleaning during operation of a hydro power plant.

Novel Oligomer Enables Green Solvent Processed 17.5% Ternary Organic Solar Cells: Synergistic Energy Loss Reduction and Morphology Fine-Tuning.

The large non-radiative recombination is the main factor that limits state-of-the-art organic solar cells (OSCs). In this work, two novel structurally similar oligomers (named 5BDTBDD and 5BDDBDT) with D-A-D-A-D and A-D-A-D-A configuration are synthesized for high-performance ternary OSCs with low energy loss. As third components, these PM6 analogue oligomers effectively suppress the non-radiative recombination in OSCs. Although the highest occupied molecular orbital (HOMO) levels of 5BDTBDD and 5BDDBDT are higher than that of PM6, the oligomers enabled ultra-high electroluminescence quantum efficiency (EQEEL ) of 0.05% and improved VOC , indicating suppressing non-radiative recombination overweighs the common belief of deeper HOMO requirement in third component selection. Moreover, the different compatibility of 5BDTBDD and 5BDDBDT with PM6 and BTP-BO4Cl fine-tunes the active layer morphology with synergistic effects. The ternary devices based on PM6:5BDTBDD:BTPBO4Cl and PM6:5BDDBDT:BTP-BO4Cl achieve a significantly improved PCEs of 17.54% and 17.32%, representing the state-of-the art OSCs processed by green solvent of o-xylene. The strategy using novel oligomer as third component also has very wide composition tolerance in ternary OSCs. This is the first work that demonstrates novel structurally compatible D-A type oligomers are effective third components, and provides new understanding of synergetic energy loss mechanisms towards high performance OSCs.

Minimization of Energy Losses in the BLDC Motor for Improved Control and Power Supply of the System under Static Load.

In this article we present the optimal method of controlling and supplying a BLDC motor under static load, proposed and implemented as a result of the research. A research infrastructure was developed to measure and analyze variants of the motor control. In the research we determine possible losses of electric energy released in the form of heat in the tested engine elements. The test results showed that the lowest energy losses are provided by the variant where the control signals are obtained from an external magnetic disc and the motor is powered by an additional DC/DC converter. The conclusions from the analyses allowed for the selection of the best variant of motor control and power supply, which minimizes energy losses during the BLDC motor operation.

Efficient organic solar cells with small energy losses based on a wide-bandgap trialkylsilyl-substituted donor polymer and a non-fullerene acceptor

Efficient organic solar cells based on a blend of PBDS-T as a donor polymer and BTP-eC9 as non-fullerene acceptor are presented and characterized. PBDS-T is an alternating copolymer that comprises easily accessible electron-rich trialkylsilyl-substituted benzodithiophene and electron-deficient benzodithiophene-4,8-dione units and that can be efficiently and reproducibly synthesized in high molecular weights, while keeping good solubility. PBDS-T exhibits a strong absorption between 450 and 700 nm and combines a wide optical bandgap of 1.86 eV, with low-lying energy levels, and a face-on molecular orientation in thin films. Organic solar cells prepared by blending PBDS-T with BTP-eC9 show considerable performance when as-cast films are annealed in solvent vapor and present a high open-circuit voltage of 0.86 V, a low photon-energy loss of 0.53 eV, and an internal quantum efficiency of 93%. The power conversion efficiency reaches 16.4%, which − to the best of our knowledge − is the highest for a conjugated polymer comprising trialkylsilyl side chains in combination with a Y6-based non-fullerene acceptor. Specifically, the trialkylsilyl side-chains of PBDS-T reduce synthetic complexity, result in a low energy loss by ensuring low energetic disorder, and provide competitive device performance.

Recent review of using nanofluid based composite PCM for various evacuated tube solar collector types

ABSTRACT Recently, solar thermal energy has been considered the main type of renewable energy used widely to provide heat energy and produce electrical power. Evacuated tube solar collectors (ETSCs) are used in various weather circumstances such as clear, cloudy, windy, hot, and cold weather, and their efficient system supplies latent heat storage fluid with higher temperature and lower heat energy loss compared to the flat-plate solar collectors (FPSCs). This review paper is considered an investigation on adding nanofluid particles to the evacuated tube solar collector-PCM, indicating future evacuated tube solar collector designs and predicting the suitable high- or low-temperature PCM for various types of applications. Also, three main types of ETSCs, heat pipe, Thermosyphon, and U-pipe, with their applications are reviewed, and the factors that influence the collector performance and efficiency are discussed. Moreover, the properties that affect the selection of the PCM and the usage of various types, sizes, and volumetric concentrations of nanofluid as a working fluid for each ETSC are investigated with their enhancements for each type. Lastly, this paper provides future ideas for using additive nanofluid materials as a working fluid to improve the performance and efficiency of ETSCs.

Figure of Merit Enhancement of Laterally Vibrating RF-MEMS Resonators via Energy-Preserving Addendum Frame.

This paper examines a new technique to improve the figure of merit of laterally vibrating RF-MEMS resonators through an energy-preserving suspended addendum frame structure using finite element analysis. The proposed suspended addendum frame on the sides of the resonant plate helps as a mechanical vibration isolator from the supporting substrate. This enables the resonator to have a low acoustic energy loss, resulting in a higher quality factor. The simulated attenuation characteristics of the suspended addendum frame are up to an order of magnitude larger than those achieved with the conventional structure. Even though the deployed technique does not have a significant impact on increasing the effective electromechanical coupling coefficient, due to a gigantic improvement in the unloaded quality factor, from 4106 to 51,136, the resonator with the suspended frame achieved an 11-folds improvement in the figure of merit compared to that of the conventional resonator. Moreover, the insertion loss was improved from 5 dB down to a value as low as 0.7 dB. Furthermore, a method of suppressing spurious mode is demonstrated to remove the one incurred by the reflected waves due to the proposed energy-preserving structure.

Low nonradiative energy losses within 0.2 eV in efficient non-fullerene all-small-molecule organic solar cells

All-small-molecule organic solar cells with high photovoltaic performance and low non-radiative energy losses ≤ 0.2 eV.

An acceptor with an asymmetric and extended conjugated backbone for high-efficiency organic solar cells with low nonradiative energy loss

An asymmetric acceptor NQF is designed to minimize the nonradiative loss. Using this acceptor, a binary OSC is fabricated and offers an efficiency of 17.57% with a low nonradiative energy loss (ΔEnr) of 0.177 eV.

Visible and Online Detection of Near‐Infrared Optical Vortices via Nonlinear Photonic Crystals (Advanced Optical Materials 1/2022)

A novel scheme of visible-detection method for near-infrared optical vortices, based on asymmetrically engineered nonlinear photonic crystals is theoretically proposed and experimentally demonstrated by Yanqing Lu, Wei Chen, Yuan Liu, and co-workers (see article number 2101098). This work provides a large-broadband wavelength, low energy loss, and multi-processing channels platform for the visible detection of near-infrared optical vortices, promising to be applied in optical communication systems.

Low energy loss (0.42 eV) and efficiency over 15% enabled by non-fullerene acceptors containing N-bis(trifluoromethyl)phenylbenzotriazole as the core in binary solar cells

Binary OSCs with an efficiency as high as 15.17% are prepared using a new acceptor with a 3,5-bis(trifluoromethyl)phenyl as the N-substituent in a benzotriazole core and a donor polymer.

Perspective on interface engineering for capacitive energy storage polymer nanodielectrics.

Polymer nanodielectrics with high breakdown strength (Eb), high energy density (Ue) and low energy loss have great potential to be used as capacitive energy storage materials of high-voltage film capacitors in modern electrical and electronic equipment, such as smart grids, new energy vehicles and pulse powered weapons. Usually, inorganic nanoparticles with high dielectric constant (εr) are added into a high Eb polymer matrix to achieve simultaneously enhanced εr and Eb, thus leading to nanodielectrics with high Ue. However, this strategy was seriously hampered by the uneven distribution of electric fields and inhomogeneous microstructures of the multi-phased nanodielectrics until increasing research work was focused on interface engineering. Recent progress in nanocomposites suggests that interface engineering plays a critical role in regulating the polarization and breakdown behaviors of the nanodielectrics, such as balancing εr and Eb, enhancing Ue and energy discharge efficiency (η). This article highlights the recent advances in the interface engineering of polymer nanodielectrics, including theoretical models, interface engineering strategies, and the latest characterization and fabrication techniques of high performance nanodielectrics. Finally, the challenges and opportunities in the interface engineering of the nanodielectrics in film capacitors are discussed and predicted from a practical point of view.

Low-temperature Electrical Properties and Correlated Barrier Hopping Conduction Mechanism in CdTiO3

CdTiO3 nanoparticles were synthesized by solid-state reaction technique. X-ray diffraction (XRD) confirms the formation of rhombohedral CdTiO3 nanoparticles and scanning electron microscopy (SEM) shows the irregularly shaped nanoparticles. The ac conductivity data was fitted using Jonscher’s power law to find the frequency exponent "s". Correlated barrier hopping (CBH) is found to be prevailing conduction mechanism from 300 K to 160 K. The density of states (DOS) calculated by applying CBH model lie in the range of 2.89 x 1020 eV-1cm-3 to 2.96 x 1021 eV-1cm-3. The calculated minimum hopping distance (Rmin) was 2.13 x 10-9 m. The low values of tangent loss (< 1) at all temperatures suggest CdTiO3 as a potential material in electrical devices with low energy losses. The shifting of maxima towards higher frequencies with the decrease in temperature in imaginary modulus plots suggests the thermally triggered hopping process in CdTiO3 nanoparticles. The modulus studies confirm that hopping is the dominant conduction mechanism in CdTiO3 nanoparticles as suggested by ac conductivity studies

Low optical diffraction random hexagonal structure metallic network conductive films

Traditional metallic meshes are a two-dimensional square structure with high optical transmittance loss, and the diffraction of light seriously interferes with the imaging quality of the detection system. In this work a metallic network conductive film with a random hexagonal surface structure is designed. This structure has a higher optical transmittance than conventional square metallic meshes. As a result of the random variables in the structure, it can also suppress the stray light of high-order diffraction. Then we prepare a metallic network conductive film on a ZnS optical window with a line width of 4 μm and a period of 100 μm. The metal lines of the sample are clear, the line width is uniform, and there is no dotted line. The transmission loss of the ZnS optical window is 10.5% in the long-wave infrared band (LWIR) band but only 6.8% in the visible band, which has low energy loss. At the same time, it can achieve uniform optical diffraction, thus reducing the imaging interference to the photoelectric detection system. The numerical simulation results show that the average EMI shielding efficiency is 37.9db, which is in an electromagnetic spectrum range from 0.2 GHz to 20 GHz, and its minimum shielding efficiency is 29.6 dB, which is 3.2 dB higher than the traditional square mesh’s. The random hexagonal structure metallic network conductive films designed and prepared in this paper have excellent optical properties and EMI shielding efficiencies, which is of great significance in improving the comprehensive performance of the graphical optical window.

Aryl-substituted-indanone end-capped nonfullerene acceptors for organic solar cells with a low nonradiative loss.

Three nonfullerene acceptors with different aryl-substituted terminal groups were designed and synthesized. The optimal device obtained a PCE of 11.42%, with a nonradiative energy loss ≤0.16 eV. Non-rigid π-extension of terminal groups is proved to be a feasible strategy to modulate the molecular packing behaviour and reduce nonradiative recombination loss.

Multi-Energy Gamma-Ray Attenuations for Non-Destructive Detection of Hazardous Materials

We present a non-destructive method (NDM) to identify minute quantities of high atomic number (Z) elements in containers such as passenger baggage, goods carrying transport trucks, and environmental samples. This method relies on the fact that photon attenuation varies with its energy and properties of the absorbing medium. Low-energy gamma-ray intensity loss is sensitive to the atomic number of the absorbing medium, while that of higher-energies vary with the density of the medium. To verify the usefulness of this feature for NDM, we carried out simultaneous measurements of intensities of multiple gamma rays of energies 81 to 1408 keV emitted by sources 133Ba (half-life = 10.55 y) and 152Eu (half-life = 13.52 y). By this arrangement, we could detect minute quantities of lead and copper in a bulk medium from energy dependent gamma-ray attenuations. It seems that this method will offer a reliable, low-cost, low-maintenance alternative to X-ray or accelerator-based techniques for the NDM of high-Z materials such as mercury, lead, uranium, and transuranic elements etc.

High energy storage density and low energy loss achieved by inserting charge traps in all organic dielectric materials

An innovative strategy of introducing space charge traps to dielectric materials is developed by copolymerization of MMA with conjugated VK, which enables superior energy storage performance (Ue = 15.7 J cm−3 @ 750 MV m−1, η = 88%).

Fiber reinforced SiC ceramic helical spring for high elasticity and large deformation at high temperature

AbstractCeramic spring devices play a significant role in mechanical systems, developing advanced ceramic helical spring with combination of high toughness and good elasticity still remains challenging. Herein, C/SiC composite helical springs with good elastic response to temperatures were fabricated by chemical vapor infiltration method. The C/SiC springs with rectangular and circular coil structures show high densities of 2.04 ± 0.162 and 1.96 ± 0.132 g/cm3, respectively. In contrast, C/SiC spring with circular coil structure can achieve high toughness of 0.92 ± 0.004 N/mm and low energy loss of 9.13 × 10−3 J at room temperature, while also exhibit an ideal spring constant of 0.35 N/mm and low energy loss of 7.82 × 10−2 J at 1000°C, which are highly comparable with those reported traditional ceramic springs. Furthermore, through finite element simulations, the stress distribution shows that both springs generate residual stresses at different temperatures after several cycles. The more uniform stress distribution and small irreversible deformation can be responsible for the superior elasticity of C/SiC spring with circular coil structure. The proposed strategy holds promising potential for developing C/SiC composite helical spring for future elastic devices used in complex and extreme service environments.