Conventional Ring Research Articles

Clar's Aromatic π‐Sextet Rule for the Construction of Red Multiple Resonance Emitter

AbstractDespite the proliferation of multiple resonance (MR) materials in the blue to green spectral ranges, red MR emitters remain scarce in the literature, an area that certainly warrants attention for future applications. Here, through a clever application of classic Clar's aromatic π‐sextet rule, we triumphantly constructed the first red MR emitter by substituting the conventional benzene ring core with anthracene (fewer π‐sextets). Theoretical studies indicate that the quantity of π‐sextets ultimately determines the optical band gap of a molecule, rather than the number of fused benzene rings. Benefiting from the high photoluminescence quantum yield of ~94 % and horizontal dipole ratio of ~90 %, the corresponding narrowband red (luminescence wavelength: 608 nm) organic light‐emitting diode shows a high external quantum efficiency of 27.3 %, with only a slight decrease of 3.7 % at an elevated luminance level of 100,000 cd/m2.

Excitation of high-quality quasi-BIC toroidal mode in a lattice perturbed terahertz metasurface

The bound state in continuum (BIC) is a phenomenon that describes the existence of nonradiative modes (dark modes) embedded in the continuum frequency range. However, an ideal BIC cannot be detected experimentally. The BIC can be transformed into a quasi-BIC by establishing a leaky channel to the radiation continuum. In this study, instead of the conventional asymmetric split ring resonator structure, a sharp quasi-BIC mode is excited in a symmetric split ring resonator (SRR) metasurface by the perturbation of the lattice constant of the unit cell via changing the interspacing distance between two adjacent SRRs. The quality factor of the quasi-BIC mode can be tuned by varying the interspacing of two SRRs, while the resonance frequency of the quasi-BIC mode remains stable. An eigenmode analysis confirms the presence of the quasi-BIC mode, while the ab initio Fano theory and a coupled oscillator model elucidate the radiative and nonradiative coupling mechanisms. The influence of geometric perturbations on the quasi-BIC mode is quantitatively assessed through the extracted fitting parameters, providing insights into the transition from the dark mode (ideal BIC) to the quasi-BIC mode. The terahertz time domain spectroscopy measurement demonstrates a signature of the quasi-BIC resonance mode as a result of the band folding in the first Brillouin zone induced by the doubling of the lattice constant.

Dose calculation accuracy of a new high-performance ring-gantry CBCT imaging system for prostate and lung cancer patients

Background and purposeThe recently introduced high-performance CBCT imaging system called HyperSight offers improved Hounsfield units (HU) accuracy, a larger CBCT field-of-view and improved image quality compared to conventional ring gantry CBCT, possibly enabling treatment planning on CBCT imaging directly. In this study, we evaluated whether the dose calculation accuracy on HyperSight CBCT was sufficient for treatment planning in prostate and lung cancer patients. Materials and methodsHyperSight CBCT was compared to planning CT in terms of HU-to-mass density (MD) calibration curves. For twenty prostate patients and twenty lung patients, differences in DVH parameters, and 3D global gamma between dose distributions calculated on planning CT and free breathing HyperSight CBCT were evaluated. For this purpose, HyperSight CBCT acquired at the first fraction was rigidly registered to the pCT, delineations from the CT were propagated and the dose was recalculated on the HyperSight CBCT. ResultsFor each insert of the HU-to-MD calibration phantom, the HU values of HyperSight CBCT and pCT agreed within 35 HU. For prostate maximum deviations in PTV Dmean, V95% and V107% were 1.8 %, −1.1 % and < 0.1 % respectively. For lung PTV V95% was generally lower (median −1.1 %) and PTV V107% was generally higher (median 1.1 %) on HyperSight CBCT due to breathing motion artifacts. The average (±SD) 2 %/2mm gamma pass rate was 98.7 %±1.2 % for prostate cancer patients and 96.2 %±2.1 % for lung cancer patients. ConclusionHyperSight CBCT enabled accurate dose calculation for prostate cancer patients, without implementation of a specific HyperSight CBCT-to-MD curve. For lung cancer patients, breathing motion hampered accurate dose calculations.

Clar's Aromatic π-Sextet Rule for the Construction of Red Multiple Resonance Emitter.

Despite the proliferation of multiple resonance (MR) materials in the blue to green spectral ranges, red MR emitters remain scarce in the literature, an area that certainly warrants attention for future applications. Here, through a clever application of classic Clar's aromatic π-sextet rule, we triumphantly constructed the first red MR emitter by substituting the conventional benzene ring core with anthracene (fewer π-sextets). Theoretical studies indicate that the quantity of π-sextets ultimately determines the optical bandgap of a molecule, rather than the number of fused benzene rings. Benefiting from the high photoluminescence quantum yield of ~94% and horizontal dipole ratio of ~90%, the corresponding narrowband red (luminescence wavelength: 608 nm) organic light-emitting diode shows a high external quantum efficiency of 27.3%, with only a slight decrease of 3.7% at an elevated luminance level of 100,000 cd/m2.

Design Optimisation of a Flat-Panel, Limited-Angle TOF-PET Scanner: A Simulation Study.

In time-of-flight positron emission tomography (TOF-PET), a coincidence time resolution (CTR) below 100 ps reduces the angular coverage requirements and, thus, the geometric constraints of the scanner design. Among other possibilities, this opens the possibility of using flat-panel PET detectors. Such a design would be more cost-accessible and compact and allow for a higher degree of modularity than a conventional ring scanner. However, achieving adequate CTR is a considerable challenge and requires improvements at every level of detection. Based on recent results in the ongoing development of optimised TOF-PET photodetectors and electronics, we expect that within a few years, a CTR of about 75 ps will be be achievable at the system level. In this work, flat-panel scanners with four panels and various design parameters were simulated, assessed and compared to a reference scanner based on the Siemens Biograph Vision using NEMA NU 2-2018 metrics. Point sources were also simulated, and a method for evaluating spatial resolution that is more appropriate for flat-panel geometry is presented. We also studied the effects of crystal readout strategies, comparing single-crystal and module readout levels. The results demonstrate that with a CTR below 100 ps, a flat-panel scanner can achieve image quality comparable to that of a reference clinical scanner, with considerable savings in scintillator material.

Early Cracking of Cementitious Materials Based on Stress Concentration Method

Abstract The traditional ring constraint shrinkage test method for detecting shrinkage cracking of cementitious materials has been found to have low cracking sensitivity and random occurrence of cracks. To address these problems, this study proposed an improvement ring constraint shrinkage test apparatus. The apparatus was used to analyze the stress distribution at key nodes and cross sections by theoretical and finite element methods. The study also counted the cracking time and crack location distribution of the improvement ring constraint specimens by test results. The findings showed that the average cracking time of the cement mortar that improved ring specimens was 52.4 % shorter than that of the conventional ring specimen. This significant reduction in the test observation period indicates that the improvement ring constraint shrinkage test method is highly efficient. Moreover, 98 % of the crack offset was within 27.35 mm of the expected cracking location, and the offset distance was negligible compared with the conductive coating length. These results suggest that the improvement ring constraint shrinkage test method can effectively limit the location of specimen cracking.

Mechanical behavior of unsaturated soils from suction controlled ring shear tests

The shear strength behavior associated with a large shear deformation of both the fine- and coarse-grained unsaturated soils is important in interpreting and forecasting the initiation and movement of landslides. For this reason, a suction-controlled ring shear apparatus was designed by introducing modifications to the conventional Bromhead ring apparatus extending the axis translation technique. A series of suction-controlled ring shear tests were performed on fine- and coarse-grained unsaturated soil specimens subjecting to large shear deformation. The experimental results are presented and interpreted for highlighting: (i) the shear stress/void ratio-shear displacement relationships; (ii) the envelopes of the residual shear strength; (iii) the void ratio, water ratio and degree of saturation of the fine-grained soil specimens sheared to the residual state under different net normal stresses and matric suctions. These results provide valuable information toward understanding and interpreting the behaviors of landslides in unsaturated soils that experience the first failure and the reactivation along a pre-sheared slip surface.

The added value of a new high-performance ring-gantry CBCT imaging system for prostate cancer patients

Background and purposeA novel Cone-Beam Computed Tomography (CBCT) named HyperSight provides superior CBCT image quality compared to conventional ring gantry CBCT imaging, and it is suitable for dose calculations for prostate cancer, but it comes with considerable additional costs. The aim of this study was to determine the added value of HyperSight CBCT imaging compared to conventional CBCT imaging in terms of organ visibility in the male pelvic region. Materials and methodsTwenty prostate cancer patients were included in this prospective clinical study. For each patient three CBCT pairs, consisting of HyperSight and conventional CBCT scans acquired on consecutive days, were included. CBCT scans were evaluated by four observers in terms of visibility of the prostate, bladder, rectum and seminal vesicles. Visibility was scored on a 1-to-5 scale and by annotating axial slices where the organs were hard to delineate. Lastly, observers indicated whether the CBCT scans were of sufficient quality for an online adaptive radiation therapy workflow. ResultsAll four organs were better visible on HyperSight CBCT scans compared to conventional CBCT scans. The mean visibility scores increased from 3.1 to 4.5 on a 1––5 scale of and the mean number of annotated slices reduced from 4.5 to 1.1. 99% Of the HyperSight CBCT scans were considered suitable for an online adaptive workflow vs 25–83% for the conventional CBCT scans. ConclusionHyperSight CBCT scans yielded a visibility of prostate, bladder, rectum and seminal vesicles comparable to planning CT scans and, can replace a repeat planning CT scan in case of anatomical changes requiring a new treatment plan.

Analysis of a passive vibration damper for high-speed superconducting magnetic bearings

Superconducting magnetic bearings (SMB) based on a combination of high temperature superconductors and permanent magnets enable the realization of self-stabilized high-speed devices with significantly reduced friction. However, external vibration might couple in the bearing resulting in large amplitude oscillations due to a resonance case. A dedicated eddy current damper (ECD) might be used to eliminate these oscillations for a stable operation. The influence of such damping elements was studied for a frictionless SMB twisting system designed to speed up the conventional ring spinning process. Therefore, conductive copper rings with different thicknesses were implemented at different positions into the bearing setup as ECD. Afterward, the SMB setup was analyzed during acceleration using an array of laser distance sensors to record the displacement of the levitating permanent magnet ring in radial and axial direction, respectively. Simultaneously, a numerical model was developed to investigate the influence of the ECDs on the dynamic and static behavior of the SMB in more detail. It was shown that the simulated damping coefficients are in good agreement with the measured values, which allows further optimization of the ECD with the developed numerical model.

Ultrahigh Q surface lattice resonance supported by a U-shaped resonant ring nanoarray.

We achieved an ultrahigh Q surface lattice resonance (SLR) using a conventional U-shaped split ring resonator (U-SRR) array. Numerical results confirmed by semi-analytical analysis show that with the transmission resonance amplitude up to 0.8, the Q-factor of the SLR can still surpass 104. The physical mechanisms of the ultrahigh Q-factor were also investigated. Besides the radiation suppression provided by conventional SLR, the unique geometry of the U-SRR can further offer dual radiation suppression mechanisms: reduction of the dipole moment and excitation of the in-plane quadrupole. We expect that the proposed ultrahigh Q SLR platform will be explored for more flexible and advanced nanoscale devices.

High-performance anti-series diode ring amplifier for switched capacitor circuits

Ring amplifiers enable efficient amplification with less power consumption. These are characterized by fairly power requirements, and innate rail-to-rail output swing and are robust against PVT variations. In this paper, we are presenting an improved self-biased anti-series diode-based ring amplifier (ASD-RAMP) design, implemented on 45-nm CMOS technology. The design uses two diode-connected PMOS transistors that are connected in an anti-series manner to generate a large resistance because of which a high dead-zone voltage is generated. The ASD-RAMP has a settling time of only 4.05 ns, which is nearly half of the conventional self-biased ring amplifier (CSB-RAMP). In comparison to CSB-RAMP, the proposed ASD-RAMP improves the dead-zone voltage by 1.1× while requiring 6.76% less power. The circuit is durable and suitable for high-performance applications since it exhibits great resilience to PVT variations in addition to the improved dead zone voltage and reduced settling time.

Comparison of 5G‐IoT antenna performance by using four distinct dielectric materials to verify their efficiencies

SummaryThe characterization of four different materials, Taconic (D1), FR4 (D2), Lab material (D3), and Created material (D4) using the ring resonator technique, is presented in this study along with a comparison of antenna performance using standard and measured dielectric constant ( ) and loss tangent ( ) values. This article discussed the comparison of antenna performances on four distinct dielectric materials to verify their efficiencies. Standard values of for the reported materials are 2.20, 4.40, 2.33, and 10.45 for D1, D2, D3, and D4, respectively, with corresponding values of 0.0009, 0.02, 0.0012, and 0.00032. The and for the materials D1, D2, D3, and D4 are calculated as 2.10, 4.56, 2.51, and 9.89 and 0.00094, 0.01927, 0.0013, and 0.0003025, respectively, using a ring resonator. The materials are utilized as the substrate for a printed single layer Y‐Shape 5G‐IoT antenna in order to validate the measured results. According to the findings of this study, the measurement of using the resonator approach exhibited errors of 4.54%, 3.63%, 7.82%, and 5.33%, respectively, while the has errors of 04.44%, 03.65%, 08.33%, and 5.47% for materials D1, D2, D3, and D4, respectively. The outcomes of this work include the numerical calculation of the and of four materials and the validation of the measured values using a Y‐Shape 5G‐IoT antenna in the millimeter‐wave 5G frequency bands. Additionally, the values calculated mathematically are compared with the values obtained from the conventional ring resonator.

Opportunities to reduce environmental burden by recycling fabric waste in a woollen fabric company

PurposeWool fiber is accepted as one of the natural and renewable sources and has been used in the apparel and textile industry since ancient times. However, wool fiber has the highest global warming potential value among conventional fibres due to its high land use and high methane gas generation. This study aimed to recycle the wool fabric wastes and also to create a mini eco-collection by using the produced yarns.Design/methodology/approachThis manuscript aimed to evaluate the fabric wastes of a woolen fabric producer company. Fabric wastes were opened with two different opening systems and fiber properties were determined. First, conventional ring yarns were produced in the company’s own spinning mill by mixing the opened fibres with the long fiber wastes of the company. In addition, opening wastes were mixed with different fibres (polyester, long wool waste, and Tencel fibres) between 25% and 70% in the short-staple yarn spinning mill and used in the production of conventional ring and OE-rotor yarns. Most of the yarns contained waste fibres at 50%. Recycled and virgin yarns were used as a weft and warp yarn and a total of 270 woven fabric samples were obtained and fabric properties were examined. Also, a fabric collection was created. A life cycle assessment (LCA) was made for one of the selected yarns.FindingsAt the end of the study, it was determined that it was possible to produce yarn and fabric samples from fiber blends containing high waste fiber ratios beyond 50%. All the woven fabric samples produced from conventional ring and OE-rotor yarns gave higher breaking, tearing and stitch slip strength values in the weft and warp direction than limit quality values of the company. In addition, abrasion resistance and WIRA steam stability properties of the fabric samples were also sufficient. Environmental analysis of the recycling of the wastes showed a possible decrease of about 9940034.3 kg CO2e per year in the global warming potential. In addition, fiber raw material expenses reduced yarn production cost about 50% in case of opened fabric waste usage. However, due to insufficient pilling resistance results, it was decided to evaluate the woven fabrics for the product groups such as shawls and blankets, where pilling resistance is less sought.Originality/valueThe original aspects of the article can be summarized under two headings. First, there are limited studies on the evaluation of wool wastes compared to cotton and polyester fibres and the number of samples examined was limited. However, this study was quite comprehensive in terms of opening type (rag and tearing), spinning systems (long and short spinning processes), fiber blends (waste 100% and blends with polyester, long wool waste and Tencel fibres) and yarn counts (coarser and finer). Recycled and virgin yarns were used as a weft and warp yarn and a total of 270 woven fabric samples were obtained using different colour combinations and weave types. All processes from fabric waste to product production were followed and evaluated. Life cycle assessment (LCA) and cost analysis was also done. The second unique aspect is that the problem of a real wool company was handled by taking the waste of the woolen company and a collection was created for the customer group of the company. Production was made under real production conditions. Therefore, this study will provide important findings to the research field about recycling, sustainability etc.

Investigating the impact of fiber and yarn structure on yarn tensile properties: A computational approach with artificial neural networks

The properties of yarns strongly depend on the fibers and spinning techniques used to manufacture them. It is imperative to investigate the influence of diverse fibers and yarn structures on the tensile properties of the yarns. Simultaneously, it is equally important to forecast these properties to mitigate costs, reduce waste, prevent faults, and achieve the desired performance in the final products. This study used three different fibers, namely conventional polyester, coolmax, and thermolite, and four different spinning techniques, namely conventional ring, compact, siro, and siro-compact spinning, to develop ring-spun yarns. The effect of fiber and spinning technique was investigated on lea strength (usually taken as count of yarn × lea strength (CLSP)), single yarn strength, and breaking elongation of the developed yarns. An artificial neural network model (ANN) was designed to predict the properties of the yarns using varying fiber types and spinning techniques. The yarns made of conventional polyester fibers resulted in the highest strength of the yarns, whereas coolmax fibers imparted maximum breaking elongation to the yarn compared with other fibers. Conventional ring spun yarns showed minimum strength, whereas siro yarns showed the highest strength among all the yarn samples. The ANN model predicted the CLSP, single yarn strength as well, and breaking elongation of the yarn with the highest accuracy as indicated by the R2-value, which suggests the model can be used reliably and accurately for the prediction of tensile properties of the yarns for different fibers and yarn structures.

734: Ethos HyperSight: what is the added value compared to conventional ring gantry cone-beam CT

734: Ethos HyperSight: what is the added value compared to conventional ring gantry cone-beam CT

A novel chain-like conjugated donor-π-acceptor molecular additive for highly efficient and stable perovskite solar cells

In donor-π-acceptor (D-π-A) molecules, the coordination ability of the acceptor can be enhanced by the directed movement of delocalized electrons (DEs) on the π-bridge. However, the conventional aromatic ring as π-bridge limits the number of DEs due to the structural characteristic, which restrict the coordination ability of the acceptor, and there is still a lack of research on this issue. Herein, we proposed a chain-like conjugated π-bridge design strategy to address this issue. The Astaxanthin with eleven contiguous C − C = C fragments was selected as a chain-like D-π-A additive for perovskite films. Twenty-two DEs in such chain-like bridge can move towards the C = O group by the D-π-A effect within Astaxanthin, which increases the electron cloud density of C = O group so that enhances its coordination capacity with cations. Ultimately, the Astaxanthin-based device achieved a champion power conversion efficiency (PCE) of 24.43 % and maintained more than 95 % and 91 % of initial PCE for aging 1000 h in dry air (RH < 1 %) and atmosphere (RH = 20 ∼ 30 %), respectively. This work provides a novel strategy to break the restriction of aromatic rings to DEs, which provides theoretical and experimental guidance for further designing chain-like D-π-A additives with strong defect passivation ability to boost photovoltaic performance of PSCs.

Mechanical Response of New Configurations Formed After Rotation of Triple Intermittent Nested Ring

Nested ring energy absorbers absorb most of the kinetic energy of an impact in an irreversible manner, reducing the damage to the human body or cargo inside the carrier in a collision. Compared to conventional single ring, nested ring can greatly increase the specific energy absorption (SEA) without significantly increasing the cost. This paper proposes a new design idea for the nested ring structure, which forms a new design by rotating the traditional configuration. Since the symmetry is broken, the deformation mode is asymmetric. Both experimental tests and finite element simulations are performed. The experimental results match the simulation results with less than 5% deviation, demonstrating the new design improves energy absorption capacity by 7% compared to previous nested ring designs.

&lt;i&gt;In Situ&lt;/i&gt; Measurement of Twist Propagation and Yarn Tension with Superconducting Magnetic Bearing Twisting Element for Ring Spinning Process

The twisting of yarn in one of the most widely used conventional ring spinning processes is based on the ring/traveler system. The existing limitation of productivity in the ring spinning process lies on the prevailing force relation between ring, traveler and yarn as well as the frictional heat between traveler and ring, principally in the ring traveler system. Recently, a frictional free twisting element based on a superconducting magnetic bearing (SMB) was developed to increase the productivity of ring spinning drastically, which was patented by ITM and Leibniz IFW Dresden. This SMB consists of a circular superconductor and a permanent magnet (PM) ring. In the superconducting state, the PM ring levitates and can freely rotate even up to an angular speed of 50.000 rpm. It is connected with the spindle via the yarn through a guide attached to the PM ring to impart yarn twist. Through the rotation of the PM ring, the twist propagates to the nip point of the delivery rollers. The twist propagation rate depends on different parameters, e.g., spindle speed, balloon geometry, and friction between yarn and yarn guides. A change in the level of twist affects the process, yarn tension, yarn breakage rate, and yarn properties. Hence, it is important to investigate the twist distribution to derive effective measures for improving the twist propagation especially at higher angular spindle speeds and thus eliminate weak points to increase process stability and yarn quality. The aim of these measurements is to analyze the twist distribution along the yarn path to understand the causes of yarn breakages. In this study, the yarn path was traced at different regions by in-situ measuring the helix angle of twisted yarn using a high-speed camera. From the recorded images, the number of twists per unit length was determined using the image processing software ‘Image J’. Thus, the measurement method allows a new insight into the problem of yarn breakages originating from twist propagation in order to take optimized measures at higher angular spindle speeds.

Implanted Rhombus Ring Partial Inset-Fed Circularly Polarized Microstrip Monopole Antenna for WBAN Applications

In the present article, a design approach to accomplish circular polarization-based rhombus ring microstrip-fed monopole antenna working at 5.8 GHz for wireless body area network (WBAN) applications is proposed. The input impedance calculation using an electromagnetic theory of transmission line in a travelling wave coupled to the parallel-plate inductor model is conducted. Radiated electric field pattern calculation of the conventional square ring microstrip patch antenna (MSPA) using Biot and Savart’s law is reported. The circular polarization of the proposed antenna is accomplished by loading the radiating path with a capacitive element sectioned in the neighbourhood of the feed line. The proposed planar monopole antenna of volume 0.38λ0×0.38λ0×0.029λ0 (λ0 is evaluated at the resonant frequency of 5.8 GHz) achieves a -10 dB impedance bandwidth of 86.20% in the band (3-8 GHz) with a stable real gain of 8.29 dBic in circular polarization at the resonant frequency of 5.8 GHz and axial ration bandwidth of about 32.75% in the (5-6.9 GHz) band. Specific absorption rate (SAR) evaluation of the studied antenna is computed numerically on a part of the human phantom model to justify its use in WBAN applications. It is noted that the maximum amount of radiation absorbed by a part of the human phantom model is limited to a maximum SAR value of 1.45 W/kg and 0.754 W/kg on 1 g and 10 g of tissue mass, respectively. The prospective design has been fabricated and tested, and the experimental results are in good agreement with the simulation outcomes.

Compact spinning: a comprehensive review of the revolution in yarn manufacturing

Compact spinning has emerged as a contemporary spinning technology that has garnered significant attention due to its capacity to produce yarns with excellent properties. The strategy is a variation of conventional ring spinning that seeks to get rid of the spinning triangle while improving the uniformity, strength, and hairiness of the yarn. In compact spinning, fiber condensation is achieved by negative pressure airflow, which compresses the fibers and reduces their thickness. This results in a higher packing density of the fibers, leading to stronger and more uniform yarns. In this article, we provide a comprehensive overview of compact spinning technology, covering its principle, fiber condensation method, and the types of machines used. The quality of the yarn is greatly influenced by various systems and parameters such as lattice apron, air suction slot geometry, airflow fields, and twist mechanism employed in compact spinning. We present a compendium of the various developments established in studies on compact spinning, which could serve as a platform for developing new techniques in compact spinning for the production of high-quality yarns with low economic burdens. This review discusses compact spinning, two main systems, machines, influential parameters/peripherals, disadvantages, and the future prospects of compact spinning. Additionally, we provide a summary of previous research on compact spinning, highlighting its benefits and advantages over traditional ring spinning. Furthermore, we discuss the impact of guiding devices and lattice apron type on yarn quality. We also explore the potential of three-dimensional (3D) printing technology in enhancing the performance and design of compact spinning machines.