Low Loss Research Articles

Multi-scenario refractive index sensor based on merging BIC in an all-dielectric metasurface

In recent years, bound states in the continuum (BICs) in the all-dielectric metasurfaces have attracted considerable attention due to the low radiation loss and large quality factor (Q-factor). In this study, we design a highly sensitive refractive index sensor working in multi-scenario based on merging quasi-BIC in the silicon nitride metasurface. By adjusting the thickness of the metasurface and keeping the structural symmetry, nine BICs distributed in momentum space form the merging BIC at the Γ point with significantly enhanced Q-factor. The transmission spectra of the metasurface sensor disperse with the refractive index in multi-scenario. The modulation depth of the Fano resonance spectrum can exceed 99.9%. The sensitivity and figure of merit of the refractive index sensor based on the merging quasi-BIC can reach 41.35 nm/RIU and 13,389.1 RIU-1 for gas, 59.05 nm/RIU and 8,415.9 RIU-1 for blood, and 66.08 nm/RIU and 8,845.8 RIU-1 for cerebrospinal fluid, respectively. Furthermore, we investigate the influence of the structural deviations on the Q-factor, which of the merging quasi-BIC maintains higher than that of the isolated quasi-BIC. Our work offers a method for designing high-sensitivity sensors working in multi-scenarios, which may hold significant potential for enhancing device performance in gas and biological detection.

Multiple morcelloma of the peritoneal cavity: a case report

Introduction. Uterine fibroids are benign monoclonal hormone-sensitive tumors arising from smooth muscle cells of the cervix or body uterus. Myomectomyhas become a treatment «golden standard» upon transition to the strategy of organ-preserving surgery. The introduction of morcellation into wide clinical practice allowed to expand the indications for laparoscopic myomectomy, which is usually much better tolerated by patients due to lower invasiveness, short period of rehabilitation and low blood loss. However, the use of morcellators along with the obvious advantages has also specific complications particularly emergence of iatrogenic parasitic fibroids of the abdominal cavity upon improper surgery technique.Aim: analysis of a clinical case of multiple morcelloma.Case presentation. Female patient I., 57 years old, underwent laparoscopic myomectomy in 2003. In 2023 during a routine examination at the Central Clinical Hospital «RZD-Medicine» multiple asymptomatic iatrogenic fibroids of the abdominal cavity were revealed. The patient underwent planned surgical intervention to remove all abnormal masses.Results. During the revision upon surgical intervention, a node of 1.5×1.5 cm was found on the parietal peritoneum along the left anterior wall, as well as a node of 1.5×1.5 cm on the parietal peritoneum along the right anterior wall. There was also observed a 2×3 cm node at the edge of the omentum. In the left and right side of peritoneum of the sacro-uterine ligament, there were found nodes of up to 1 cm in size. In the area of the small intestinal mesentery, a dense node of 4.5 cm was observed 70 cm away from the ileocecal valve. Due to small size, all the fibroids were extirpated and removed from the abdominal cavity without morcellation, complete hemostasis was performed. No complications were noted during postoperative period.Conclusion. Iatrogenic fibroids are quite rare but nevertheless a potential complication of laparoscopic myomectomy. Gynecologists should pay special attention to follow proper technique upon surgical intervention. Morcellation and subsequent extraction of fibroids should be performed strictly with use of airtight container to avoid ingress of myomatous tissue into the abdominal cavity followed by emergence of iatrogenic fibroids.

An Overview of the R&D of Flywheel Energy Storage Technologies in China

The literature written in Chinese mainly and in English with a small amount is reviewed to obtain the overall status of flywheel energy storage technologies in China. The theoretical exploration of flywheel energy storage (FES) started in the 1980s in China. The experimental FES system and its components, such as the flywheel, motor/generator, bearing, and power electronic devices, were researched around thirty years ago. About twenty organizations devote themselves to the R&D of FES technology, which is developing from theoretical and laboratory research to the stage of engineering demonstration and commercial application. After the research and accumulation in the past 30 years, the initial FES products were developed by some companies around 10 years ago. Today, the overall technical level of China’s flywheel energy storage is no longer lagging behind that of Western advanced countries that started FES R&D in the 1970s. The reported maximum tip speed of the new 2D woven fabric composite flywheel arrived at 900 m/s in the spin test. A steel alloy flywheel with an energy storage capacity of 125 kWh and a composite flywheel with an energy storage capacity of 10 kWh have been successfully developed. Permanent magnet (PM) motors with power of 250–1000 kW were designed, manufactured, and tested in many FES assemblies. The lower loss is carried out through innovative stator and rotor configuration, optimizing magnetic flux and winding arrangement for harmonic magnetic field suppression. Permanent magnetic bearings with high load ability up to 50–100 kN were developed both for a 1000 kW/16.7 kWh flywheel used for the drilling practice application in hybrid power of an oil well drilling rig and for 630 kW/125 kWh flywheels used in the 22 MW flywheel array applied to the flywheel and thermal power joint frequency modulation demonstration project. It is expected that the FES demonstration application power stations with a total cumulative capacity of 300 MW will be built in the next five years.

Mid‐Infrared Sensing Using a Hollow–Core Fiber in a Nonlinear Interferometer

AbstractIncreasing the interaction path length is a well‐known method for enhancing the sensitivity of the optical detection system. Hollow–core fibers (HCFs) represent a viable alternative to the traditional multi‐path cells offering low optical losses and strong confinement of the optical field. Here, the incorporation of an Antiresonant Hollow–core Fiber (AR‐HCF) section into a nonlinear interferometer, where the AR‐HCF section serves as a gas‐sensing cell operating in the IR range is presented. By exploiting the effect of nonlinear interference, the detection is brought into the more operation‐friendly visible range. The detection of methane (CH4) gas at mid‐IR wavelengths within a half‐meter section of AR‐HCF, with an estimated concentration accuracy of 200 ppm·m is demonstrated. These results represent the combination of two research fields within a single instrument and pave the way for further advancement of quantum‐inspired gas sensing techniques.

Enhanced Energy Storage Performance of Lead-Free Sr0.7Bi0.2TiO3 Ceramics via Tape Casting.

Abstract The development of pulsed power technology demands high energy storage density dielectric materials. In this study, Sr0.7Bi0.2TiO3 relaxor ferroelectric ceramic thick films were prepared using a tape-casting process. The ceramics exhibit a dense structure and typical relaxor ferroelectric hysteresis curves, achieving an energy storage density of 4.77 J/cm³ and efficiency of 94.4%, attributed to the high polarization intensity, low remnant polarization, and low hysteresis loss of relaxor ferroelectrics. Additionally, the material demonstrates good temperature stability. Moreover, the Sr0.7Bi0.2TiO3 ceramic thick films show advantages in charge-discharge performance, capable of discharging within hundreds of nanoseconds and achieving a power density of 137 MW/cm³. Overall, the Sr0.7Bi0.2TiO3 ceramic thick film exhibits a comprehensive performance advantage in terms of energy storage density, efficiency, and power density. Additionally, the material was fabricated using the tape-casting process, which is compatible with subsequent multilayer ceramic capacitor (MLCC) production, indicating potential for further performance enhancement.

Photothermal Induced Dual-Interface: Accelerating Sustainable Hydrogen Evolution from Formic Acid.

Formic acid (FA), a liquid hydrogen storage carrier, can release hydrogen via photothermal catalysis, providing a clean and sustainable solution toward a carbon-neutral energy cycle. Despite recent advances in the design of efficient catalysts, the development of advanced systems with high H2 yield, stability, and durability remains challenging due to the inefficient photothermal conversion and mass transfer in the traditional liquid-solid bulk system, as well as the trade-off between hydrogen storage density and dehydrogenation rate. Here, we address these challenges by creating a photothermal-induced dual-interface characterized by high spectral absorption and low heat loss, a facile supply of FA, and vaporization of FA to minimize the energy barrier of the reaction. As a result, a record hydrogen evolution rate (200.9 mmol g-1 h-1) is achieved in a high concentration (26 M) of FA, which is about 15 times higher than the liquid-solid bulk system. In addition, it can be operated continuously for more than 192 h without additive addition and energy consumption, providing a strategy for accelerating interfacial mass transfer to improve catalytic activity, and also presents a reference for sustainable hydrogen production.

A microstrip bandpass filter using coupled lines loaded by open stubs

A compact simple structure bandpass filter based on terminated three coupled line structures with high selectivity is introduced through odd and even-mode analysis. The proposed filter consists of three coupled lines loaded by open and short circuit stubs. The parallel-coupled lines structure is used to obtain high selectivity with transmission zeros near the passband. Meanwhile, simultaneously tuning on bandwidth and center frequency are introduced by coupled line. One type of bandpass filter based on terminated coupled line structure is theoretically analyzed, simulated, and measured. The stepped impedance structures at the input and output ports have been used to improve the attenuation level at the stopband region and create the multiple attenuation poles. The center frequency of 1.3 GHz, the fractional bandwidth (FBW) of about 65%, the low insertion loss of 0.25 dB, and the high return loss of 30 dB are obtained. Also, a flat group delay lower than 1.4 ns is achieved. Experimental and simulated results are presented, which are in good agreement.

Leaf Identification in High-Density LiDAR-RGB Data

Abstract. Leaf detection through automated segmentation of 3D data is becoming a crucial technique in many applications of digital agriculture. Some 3D segmentation techniques that can be mentioned are based on normal differences and median normalised vector growth. However, applying these approaches to high canopy density data remains challenging. In this study, we propose a processing flow for leaf detection in high canopy density LiDAR-RGB point clouds. First, a noise removal technique inspired by Moving Least Squares (MLS) was applied to the LiDAR point cloud, and a RGB colour was assigned to each point by combining computer vision and photogrammetric methods. Moreover, once the data were suitable for leaf detection, the branches were filtered using the Statistical Outlier Removal (SOR) filter based on an analysis of the statistical behaviour of the neighbourhood. Afterwards, an unsupervised DBSCAN (Density-Based Clustering Non-Parametric Algorithm) method was used to segment similar points. Finally, the points within each cluster were identified as leaf or non-leaf using the RGB values implemented by our method; ground points were filtered out using a maximum height threshold. As a result, the leaf, non-leaf, and ground point identifiers were correct in 98.9% of cases, with the branch filtering technique SOR proving effectiveness in removing branches with low information loss and without additional complex point densification steps in reconstruction. This SOR-based solution overcomes major challenges in semantic segmentation (leaves and branches) in high-density data and potentially contributes to precision agriculture.

Local adaptive insulation in amorphous powder cores with low core loss and high DC bias via ultrasonic rheomolding

Amorphous powder cores are promising components for next-generation power electronics. However, they present inherent challenges of internal air gaps and stresses during cold compaction, which significantly deteriorate soft magnetic properties. Here, we report the formation of a local adaptive insulation structure of biconcave lens in amorphous powder cores by ultrasonic rheomolding. Consequently, compared with conventional cold-compacted powder cores, the ultrasonic rheomolded powder cores offer significant simultaneous improvements in the permeability from 31.3–32.4 to 41.8–43.3 and the direct-current bias performance from 69.4–69.7% to 87.4–87.8% (7960 A/m), thereby overcoming the trade-off between permeability and direct-current bias performance. In particular, their core losses are as low as 13.73–15.45 kW/m3, approximately one twentieth of that of the cold-compacted powder cores (282.84–304.03 kW/m3) at a magnetic field of 100 mT and 100 kHz. The biconcave-lens insulation structure can effectively buffer the impact of high mechanical stress on the magnetization of magnetic powder particles, allowing for the ultrasonic rheomolded powder cores to maintain better magnetization efficiency and consequently resulting in excellent soft magnetic properties under the cooperative effect of very low internal stresses and low porosity. The ultrasonic rheomolded powder cores can be used as alternative core components in next generation miniaturized power electronics.

Is Endoscopic Surgery a Safe and Effective Treatment for Lumbar Disc Herniation? A Meta-Analysis of Randomized Controlled Trials.

Systematic Review. This meta-analysis systematically evaluates the safety and effectiveness of endoscopic techniques in the treatment of lumbar disc herniation (LDH). A comprehensive computerized search was conducted on PubMed, Embase, Cochrane Library, China National Biomedical Literature Database (CBM), VIP Database, China National Knowledge Infrastructure (CNKI) and Wanfang Database. Randomized controlled trials (RCTs) comparing endoscopic techniques with non-endoscopic techniques for the treatment of LDH were identified. Meta-analysis was performed using RevMan 5.4 software. Seventeen RCTs involving 1748 LDH patients were analyzed. The meta-analysis revealed that, compared to the non-endoscopic discectomy (NED) group, the endoscopic discectomy (ED) group exhibited significantly lower intraoperative blood loss [MD = -74.45mL, 95% CI (-124.88, -24.02), P = .004], shorter hospitalization duration [MD = -4.07days, 95% CI (-6.67, -1.48), P = .002], lower Visual Analogue Scale (VAS) pain scores at the last follow-up [MD = -.35, 95% CI (-.63, -.07), P = .01], and a lower incidence of complications [RR = .35, 95% CI (.25, .48), P < .00001]. Moreover, the ED group exhibited a higher ratio of excellent and good therapeutic effects postoperatively [RR = 1.05, 95% CI (1.01, 1.10), P = .01]. However, there were no statistically significant differences between the 2 groups in terms of the Oswestry Disability Index (ODI) scores at the last follow-up [SMD = -.49, 95% CI (-1.14, .17), P = .14] and operation time [MD = -10.17min, 95% CI (-27.05, 6.71), P = .24]. Endoscopic techniques in the treatment of LDH exhibit significant superiority in intraoperative blood loss, hospitalization duration, postoperative pain, complication rates, and postoperative therapeutic effects. This provides patients with a safer and more effective treatment option.

Lower Blood Loss with Bicruciate-Retaining Total Knee Arthroplasty Compared with Bicruciate-Stabilized Total Knee Arthroplasty.

Total knee arthroplasty (TKA) is a common surgical procedure to treat end-stage knee osteoarthritis. This study compared blood loss volume and other clinical outcomes between bicruciate-retaining (BCR) and bicruciate-stabilized (BCS) TKA. Ninety-seven participants who underwent unilateral TKA were enrolled. The BCS-TKA and BCR-TKA groups comprised 78 and 19 participants, respectively. Blood loss was calculated using preoperative and postoperative hematocrit values, height, weight, and sex. Measurements were taken immediately after surgery, on days 1 and 7, and total blood loss was calculated up to day 7. Operation time, range of motion at 7 and 14 days postoperatively, blood transfusion requirement, and postoperative complications such as infection, hematoma, and deep vein thrombosis were compared between the groups. Blood loss was comparable between groups at all time points (125.7 vs. 105.4 mL, 57.9 vs. 43.5 mL, and 68.2 vs. 41.7 mL for immediate, day 1, and day 7 postoperatively, respectively; all p > 0.05) except for total blood loss, which was significantly lower in the BCR group compared with the BCS group (190.7 vs. 251.1 mL; p < 0.05). The BCR group also had a longer operation time than the BCS group (131.2 vs. 112.4 minutes; p < 0.05). No other significant differences were observed in other outcomes. Total blood loss up to 7 days postoperatively was significantly lower in the BCR group than in the BCS group despite a longer operation time. This may be attributed to the reduced bone resection and greater soft tissue preservation, including the anterior cruciate and posterior cruciate ligaments, in the BCR technique.

Cyanate Ester/TiO2 Composites for High‐Temperature and Miniaturized Microwave Substrate Applications

High‐temperature‐withstanding TiO2‐reinforced cyanate ester composites are developed by mechanical stirring, followed by curing at elevated temperatures. The uniform dispersion of the filler is confirmed using scanning electron microscopy and electron dispersive spectroscopy. All composites, up to a filler fraction of 30 vol%, exhibit a density of more than 90% while it reduces significantly after that. A high relative permittivity of 7.6 and a low loss tangent of 0.0112 are observed for the optimally filled 30 vol%. The addition of the filler further improves the temperature‐withstanding capability of the cyanate ester matrix. Moreover, a high thermal conductivity of 0.543 W mK−1, improved hardness of 24.88 HV, ultimate tensile strength of 11.68 MPa, and a low coefficient of thermal expansion of 36.44 ppm °C−1 are also shown by the optimally filled sample. A moisture absorption of 0.072 vol% observed for the optimal filled sample comes within the limit for microwave substrate applications. Thus, the developed composites are suitable candidates for high‐temperature microwave electronic applications.

Halogenated Polycyclic Aromatic Hydrocarbon for Hole Selective Layer/Perovskite Interface Modification and Passivation for Efficient Perovskite‐Organic Tandem Solar Cells with Record Fill Factor

AbstractPerovskite whentandemed with organic photovoltaics (OPV) for double‐junctions have efficiencypotentials over 40%. However, there is still room for improvement suchas better current matching, higher fill factor, as well as lower voltage and fill factor losses in the top perovskite cell. Here weaddress the issue associated with the top perovskite cell by utilising anovel halogenated polycyclic aromatic hydrocarbon compound, 1‐naphthylammoniumchloride (NA─Cl) playing dual roles of surface modification for the hole selectivelayer (HSL) and passivation of HSL/perovskiteinterface. Results of X‐ray photoelectron spectroscopy and density functionaltheory calculations reveal that NA─Cl retains self‐assembly property for the HSLwhile demonstrating high dipole moment and polarizability. This induces asurface dipole at the HSL/perovskite interface reducing the energetic barrierfor hole extraction by 210 meV thereby enhancing voltage output and fill factorof the device. Such scheme when implemented in a high bandgap (1.78 eV)perovskite solar cell, results in a respectable efficiency of 19.7% and thehighest fill factor of 85.4% amongst those of 1.78 eV perovskite cells reported.We have also achieved 23% cell efficient monolithic perovskite‐OPV tandem withan impressive fill factor of 84%, which is the highest for perovskite‐OPVtandem cells reported to‐date.

Enhanced Thermal and Flexural Properties of Alkalized Date Palm/Kenaf Fiber-Reinforced Epoxy Hybrid Composites: A Comparative Study of Untreated and Treated Fibers

ABSTRACT This study evaluates the thermal and mechanical behavior of hybrid composites made from date palm (DP) and kenaf fibers (KF) in an epoxy thermoset matrix. Both DP and KF fibers are abundant and renewable, reducing environmental impact. KF offers high tensile strength and stiffness, improving composite strength and rigidity, while DP fibers offer toughness and impact resistance, enhancing durability. The composites were developed in 30%, 50%, and 70% DP-KF compositions using layup and hot-pressing methods. Fiber treatment through alkalization was analyzed for its impact on mechanical and thermal properties to find the optimal fiber ratio. The hybrid composites were subjected to DMA, TGA, and flexural tests. The treated composites exhibited fewer impurities and increased cellulose content, resulting in enhanced flexural performance. This improvement was evident through higher storage modulus, lower loss modulus, and reduced tan δ when exposed to thermal stress. The 30% DP and 70% KF composites exhibited best performance. The treated 30DP-70KF exhibited improvement in the flexural strength and modulus by 13.8% and 2.7%, respectively. TGA demonstrated that treated 30DP-70KF composites had a higher glass transition temperature (Tg) and better thermal degradation resistance. These findings highlight the potential of natural fiber hybrids in creating sustainable, high-performance composite materials for construction and industrial applications.

PARMS coating technology for UV to IR laser applications

AbstractReactive sputtering using a medium frequency (MF) dual magnetron source is an advanced technique widely employed in various thin film deposition applications. For the production of high‐quality optical filters based on oxides with low losses, it is crucial to exclude any form of arcing, including both strong arcs and microarcs. These requirements are solved by plasmaassisted reactive magnetron sputtering (PARMS), which also provides a high deposition rate contributing to the economically efficient production of high‐end optical filters.

Polymer nanocomposites based on flexible BaTiO3 networks anchored with gold nanoparticles towards simultaneous high dielectric permittivity and low loss

Polymer nanocomposites based on flexible BaTiO3 networks anchored with gold nanoparticles towards simultaneous high dielectric permittivity and low loss

First Principle Study of Electronic, Optoelectronic, and Thermoelectric Properties of Zintl Phase Alloys BaAg2X2 (X = S, Se, Te) for Renewable Energy

Novel Zintl phases exhibiting promising thermoelectric properties have garnered considerable traction, largely attributed to the accuracy of computational estimates. In the present investigation, the density functional theory-based WIEN2k code is employed to analyze the structural, optoelectronic, and transport behavior of the BaAg2X2 (X = S, Se, Te) Zintl phase. All these compositions belong to the stable trigonal phase with nominal expansion in the unit cell with the replacement of S with Se and Te. A negative value of enthalpy of formation of -2.30, -2.0, and -1.80 for BaAg2S2, BaAg2Se2, and BaAg2Te2, respectively, assures their thermodynamic stability. These compositions demonstrate dynamic stability, as evidenced by the nonexistence of negative (-ve) frequency values in their phonon spectra. Increasing the size of chalcogens enhances the spin-orbit coupling and reduces the bandgap value from 2.10 - 1.55 eV. The examination of optical response suggests that studied compositions display high absorption and low energy loss in the visible range, rendering them suitable for optoelectronic devices. The temperature-dependent transport behavior is computed using BoltzTrap code, and the RT value of power factor is recorded as 0.89 × 1011, 0.65 × 1011, and 0.54 × 1011 Wm− 1K− 2 for BaAg2X2 (X = S, Se, Te). A high power factor value at elevated temperatures indicates the promising efficacy of studied compositions in thermoelectric device applications.

Borosilicate glass with low dielectric loss and low permittivity for 5G/6G electronic packaging applications

A phase-separated borosilicate glass, with a relative permittivity ranging from 3 to 3.5 and a loss tangent as low as 5.6 × 10−4, is presented for packaging applications for the next generation of mobile communications. Ionic polarizability for each borosilicate composition was calculated from the Clausius–Mossotti relationship for both the vitreous and crystalline structures, and the polarizability difference between the two is proportional to the dielectric loss. Small amounts of alkali modifier were added to improve the glass processability, and the loss tangent increased to the 1–7 × 10−3 range. The resulting glass is phase-separated, which has no impact in the millimeter-wave spectrum, as the wavelengths are considerably greater than the length scale of each immiscible phase.

Towards sustainable electronics: High-performance biodegradable polymer-based dielectric composite utilizing hydroxyapatite from cattle bone waste

Polymer-based film capacitors find widespread use in electronics and electrical systems, but the utilization of non-biodegradable dielectric materials contributes to excessive electronic waste. To address this issue, a biodegradable composite of hydroxyapatite (HAp) and poly (butylene adipate-co-terephthalate) (PBAT) was prepared and extensively characterized. HAp, as a filler, was synthesized via biomass-derived bone waste pyrolysis. The analyses confirmed successful HAp synthesis with high crystallinity and well-defined grain boundaries, which promote interfacial polarization and charge storage capability. The composite exhibited remarkable dielectric properties, with high dielectric constant, low dielectric loss, and good breakdown strength at low filler content. The PBAT/HAp-3 % composite showed significant energy storage density improvement (3.56 J/cm3), 43.55 % higher than pure PBAT (2.48 J/cm3), alongside enhanced mechanical properties and thermal stability. This study presents a cost-effective, eco-friendly route for next-generation high-performance disposable electronics.

AgNWs self-assembly along coaxially electrospun SEBS-PVP core-sheath fibers for stretchable conductive membranes with low interfacial losses

AgNWs self-assembly along coaxially electrospun SEBS-PVP core-sheath fibers for stretchable conductive membranes with low interfacial losses