Minimal Insertion Research Articles

Investigating the stability of chimeric murine polyomavirus VP1 Capsomeres via molecular dynamics simulations and experimental analysis

The development of modular virus-like particle (VLP) vaccine platforms with genetically inserted antigens in viral structural proteins shows great promise for advancing vaccine technology. However, the instability of many constructs leads to trial-and-error approaches, and the challenge of predicting stability based solely on amino acid sequences remains unresolved, yet highly appealing. This study evaluates the stability of wild-type murine polyomavirus (MPV) VP1 capsomeres and three engineered chimeric variants using molecular dynamics (MD) simulations and laboratory experiments. MD simulations, based on AlphaFold2 predictions and up-to-date all-atom force fields, accurately predicted the thermal stability and hydrophobicity of VP1-based capsomeres. Thermodynamic analysis revealed that binding energies from simulations reliably indicate thermal stability. Experiments and simulation results showed that inserts influence the stability of capsomeres differently, with larger insertions generally having a greater impact on the structures of capsomeres. This leads to increased intra-subunit distances and a higher proportion of flexible regions in the capsomere chassis. Capsomeres with less compact structures were found to have lower thermal stability. Specifically, the thermal transitional temperature (Tm) of the wild-type capsomeres was 46.9 °C, while the Tm values of the three chimeric derivatives were 42.0 °C, 38.8 °C, and 37.7 °C, reflecting a correlation between decreased thermal stability and reduced structural compactness. This research presents a robust approach for predicting the stability of novel VLP constructs based on amino acid sequences, potentially enhancing vaccine design by reducing failures, and suggests a shift towards minimal epitope insertions for improved stability.

Single- and dual-band high-order polarization rotating frequency selective surface

Abstract This work presents the design and development of dual- and single-band polarization rotating frequency selective surfaces (PR-FSSs) based on aperture-coupled patch multimode resonators. Initially, an open-loop slot is incorporated into the patch of a second-order resonator to design a dual-band second-order PR-FSS (DPR-FSS), which enables effective polarization rotation and frequency selection across two distinct passbands. Then, to develop a single-band fourth-order PR-FSS (SPR-FSS), we introduce a metallic via into the DPR-FSS. This modification results in a single-band fourth-order response. The SPR-FSS offers a bandwidth of 41% with minimal insertion loss and high roll-off characteristics. Finally, experiments are conducted to verify the performance of the proposed structures. Good agreement can be observed between simulation and measurement.

Graphene modulator and 2-bit encoder based on plasma induced transparency effect

Within this study, a periodic metasurface structure made up of two graphene strips, two fan-shaped graphene and a square ring graphene with notches is introduced to achieve plasma-induced transparency (PIT). The PIT effect is analyzed utilizing the Lorentz oscillatory coupling model, and it has been discovered that the theoretical values closely match the simulated values. The role of the Fermi level adjustments in graphene on the PIT effect was examined, and the PIT window was dynamically modified as the Fermi level changed, which was used to realize a 2-bit graphene encoder at 5.78 THz and 7.18 THz. The encoder boasts a greatest modulation depth of 80.9 % and exhibits a minimal insertion loss of 0.17 dB. By controlling the polarization direction of the incident photoelectric field, a high performance dual-channel switching modulator is successfully realized. Moreover, by increasing carrier mobility, the depth of modulation for the modulator at 11.22 THz is increased from 97.5 % to 99.5 %, and the insertion loss has dropped from 0.075 dB to 0.06 dB. In addition, the structure has superior sensing properties and slow light properties, featuring a sensitivity reaching up to 1.07 THz/RIU and a maximum group index of 293. The outcomes of our study contribute novel insights for the advancement of modulator, encoder, sensor technology and slow-light devices.

Silicon nitride directional coupler-based polarization beam splitter utilizing shallow ridge waveguides for improved fabrication tolerance

This study presents the design and fabrication of a silicon nitride (Si3N4) asymmetrical directional coupler (DC)-based polarization beam splitter (PBS) utilizing a shallow ridge waveguide structure. The use of Si3N4 with a moderate refractive index contrast and the design of a shallow ridge waveguide enables the DC structure to have a wider coupling gap of approximately 600 nm, which can be readily achieved with standard I-line lithography. The simulation results indicate that the polarization splitting is highly efficient with minimal insertion loss. This is corroborated by the experimental measurements, which show consistent broadband performance. The fabricated polarization beam splitter (PBS) exhibits a high polarization extinction ratio (PER) of over 20 dB for both transverse electric (TE) and transverse magnetic (TM) modes across a broad bandwidth of 120 nm (1500–1620 nm). This work demonstrates the potential of shallow ridge Si3N4 waveguides to enhance the fabrication tolerance and performance of integrated photonic devices.

Ionogels, Promising Exploration for Flexible Optically Transparent Tunable All‐Dielectric Electromagnetic Metamaterials

AbstractIonogels, as a novel class of environmentally friendly electronic materials, have received extensive attention. This study successfully prepared P(AM‐co‐AA) ionogel with optical transparency and flexibility via chemical polymerization. Experimental outcomes reveal that the dispersion of anions and cations within the ionogel is effectively controlled by the polymer network, resulting in distinct dispersive dielectric property, which is suitable for applications in electromagnetic metamaterials. Leveraging these properties, two distinct electromagnetic metamaterial devices are developed: An Ionogel‐based Broadband Absorber achieves over 90% absorption across 10.9–25.36 GHz, and An Ionogel‐based Frequency Selective Rasorber (FSR) transmits within 4.62–5.86 GHz, exhibiting minimal insertion loss −1.45 dB and achieves greater than 90% absorption from 13 to 17.8 GHz. High agreement between experimental results and simulations validates the feasibility of utilizing ionogel in electromagnetic metamaterial applications and introduces a novel paradigm and methodology for designing and fabricating flexible electromagnetic metamaterial devices.

Extra-Articular Distal Femoral Fractures Retrograde Nailing Versus Locked Plating A Systematic Review and Meta-Analysis

Abstract Background Extra-articular Distal femoral fractures remain a challenging matter due to the high energy trauma causing the injury and the association with soft tissue injury, vascular injury and physical disability. Different methods of fixation exist depending on a lot of factors; patient related factors, type of fractures, surgeon’s preferences. Aim of the Work to evaluate the outcome & complications of retrograde intramedullary nailing versus locked plating in management of extra-articular distal femur fractures. Patients and Methods The standard method of management of extra-articular distal femur fractures including either internal fixation by intramedullary nailing (Antegrade or Retrograde) or distal femur locked plate (LP). Results Retrograde nailing shows superiority over the Antegrade nailing especially the very distal fractures and the associated intra-articular extension. However every methods comes with its own advantage and disadvantage. Retrograde nailing gaining its popularity due to minimal insertion point and maintaining the fracture hematoma. Distal femur locked plate witnessed a lot of development including; multidirectional locking mechanism which comes very handy especially with osteoporotic bone and intra-articular extension; also the development of minimally invasive percutaneous osteosynthesis technique and system reducing time, blood loss and soft tissue dissection. Conclusion The present review shows lesser mean fracture union time and a lesser overall complication favoring the Retrograde Intramedullary Nailing (RIMN) over the Locked Plating (LP). We didn’t find a statistical significant difference between the two groups in non-union, delayed-union, mal-union, knee stiffness, knee pain, superficial/deep infection; implant related complication, re-operation rate and duration of surgery. But a less intra- operative blood loss and a better post-operative knee range of movement was seen in the LP group. Both the options of fixation appear to be feasible options, and specific indications should be considered for making the final choice.

A High Q Lamb Wave Resonator with Dummy Toes Based on 20% ScAlN Film

Abstract The lamb wave resonator (LWR) based on aluminum nitride (AlN) films are preferred strategy for high-frequency filters in 5G communication due to the tunable electromechanical coupling and high Q value. However, since the low electromechanical coupling and piezoelectric coefficient of AlN films, conventional lamb filters are difficult to meet the requirements of high bandwidth and low loss. This work proposes a lamb wave resonator with dummy toes (DT-LWR) based on scandium-doped aluminum nitride (ScAlN) film to improve the quality factor(Q) meanwhile suppress the spurious modes. The processed DT-LWR was tested using a vector network analyser (VNA, Keysight N5222B), and the MBVD model was used to fit the Z parameters. The Q value of DT-LWR is 1437.23, while that of LWR is 1250.09. It is increased by 14.97%. The enhancements make the DT-IWR as an ideal for filters with minimal insertion loss.

Evaluation of a Slim Modiolar Electrode Array: A Temporal Bone Study.

Evaluation of the Slim Modiolar (SM) electrode in temporal bones (TB) will elucidate the electrode's insertion outcomes. The SM electrode was designed for atraumatic insertion into the scala tympani, for ideal perimodiolar positioning and with a smaller caliber to minimize interference with cochlear biological processes. The SM electrode was inserted into TBs via a cochleostomy. First, the axial force of insertion was measured. Next, TBs were inserted under fluoroscopy to study insertion dynamics, followed by histologic evaluation of electrode placement and cochlear trauma. A subset of TBs were inserted with the Contour Advance (CA) electrode for comparison. Sixteen of 22 insertions performed to measure the axial force of insertion had flat or near zero insertion force profiles. Six insertions had increased insertion forces, which were attributed to improper sheath depth before electrode insertion. Under real-time fluoroscopy, 23 of 25 TBs had uneventful insertion and good perimodiolar placement. There was 1 scala vestibuli insertion due to suboptimal cochleostomy position and 1 tip roll over related to premature electrode deployment. When compared with the CA electrode, 14 of 15 insertions with the SM electrode resulted in a more perimodiolar electrode position. No evidence of trauma was found in histologic evaluation of the 24 TBs with scala tympani insertions. TB evaluation revealed that the SM electrode exerts minimal insertion forces on cochlear structures, produces no histologic evidence of trauma, and reliably assumes the perimodiolar position. Nonstandard cochleostomy location, improper sheath insertion depth, or premature deployment of the electrode may lead to suboptimal outcomes.

FACTFINDERS FOR PATIENT SAFETY: Minimizing risks with cervical epidural injections

This series of FactFinders presents a brief summary of the evidence and outlines recommendations to minimize risks associated with cervical epidural injections.Evidence in support of the following facts is presented.Minimizing Risks with Cervical Interlaminar Epidural Steroid Injections – 1) CILESIs should be performed at C6-C7 or below, with C7-T1 as the preferred access point due to the more generous dorsal epidural space at this level compared to the more cephalad interlaminar segments. This reduces the risk of the minor complication of dural puncture and the major complication of spinal cord injury due to inadvertent needle placement. 2) LF gaps are most prevalent in the midline cervical spine. This can result in diminished tactile feedback with loss of resistance (LOR), increasing the risk for inadvertent dural puncture or spinal cord injury. Based on current evidence, needle placement in the paramedian portion of the interlaminar space is safest to avoid LF gaps. 3) An optimal AP trajectory view and the physician's ability to discern engagement in the LF and subsequent LOR are crucial. Confirmation of minimal needle insertion depth relative to the ventral margin of the lamina with either a lateral or contralateral oblique (CLO) safety view is critical to minimize the risk of inadvertently inserting the needle too ventral. 4) There have been closed claims and case reports of patients who have suffered catastrophic neurologic injuries while receiving CILESIs under deep sedation. If sedation is administered, the least amount necessary should be utilized to ensure the patient can provide verbal feedback during the procedure. 5) CILESIs are an elective procedure; therefore, necessity and likelihood of benefit must be foremost considerations. Current guidelines recommend holding ACAP therapy before CILESIs due to the potentially catastrophic complications associated with epidural hematoma (EH) formation. However, there is also a risk of severe systemic complications with ceasing ACAP in specific clinical scenarios. The treating physician is obligated to determine if the procedure is indicated and can ultimately decide to delay the intervention or not perform the procedure if the benefit does not outweigh the risks.Minimizing Risks with Cervical Transforaminal Epidural Steroid Injections – the Role of Preprocedural Review of Advanced Imaging -- Variations in vascular anatomy may warrant a modified approach to CTFESI. Preprocedural review of cross-sectional imaging can provide critical information for safe injection angle planning specific to individual patients and may help to decrease the risk of unintended vascular events with potentially catastrophic outcomes.Safety of Multi-level or Bilateral Fluoroscopically-Guided Cervical Transforaminal Epidural Steroid Injections -- Safe performance of a CTFESI procedure requires the ability to detect inadvertent arterial injection. Contrast medium placed into the epidural space and/or along the exiting spinal nerves during an initial CTFESI may obscure the detection of inadvertent cannulation of a radiculomedullary artery by a subsequent CTFESI. While no available literature directly addresses the potential risk that exists with a multi-level or bilateral CTFESI, caution is still warranted.

Filter cable design with defected conductor transmission structures

Electrical cables, as the industry’s blood vessels and nervous system, require evolving distributed filtering for complex electromagnetic environment adaptability. This article introduces a filter cable design featuring an insulated cylinder coated with a defected conductor transmission structure (DCTS). The DCTS, with a well-designed etched pattern, functions as a boundary condition for transmitting specific frequency electromagnetic waves, similar to a lumped filter circuit. To validate this method, a low-pass filter cable is proposed with six-slot-ring defected structures, utilizing polytetrafluoroethylene as the inner dielectric, encased within a flexible printed circuit board (FPCB)-manufactured DCTS. The proposed cable, with precise dimensions (2.4 mm diameter, 340 mm length), demonstrates minimal insertion loss ( < 0.38 dB below 6 GHz) in the passband and rejection exceeding 23 dB at 7.7-25 GHz in the stopband. Further enhancements achieve attenuation exceeding 50 dB in the stopband (7.1 GHz to 20 GHz). Compared to traditional cables, this filter cable addresses electromagnetic compatibility (EMC) by cutting off the interference coupling path.

Automated fiber switch with path verification enabled by an AI-powered multi-task mobile robot

As the capacity of optical transport networks undergoes significant growth, there is an ongoing discussion on how to effectively leverage both spectral and spatial degrees of freedom to scale future network capacity. This paper presents an artificial intelligence (AI)-powered multi-task robot comprising a collaborative robotic arm and a mobile robotic base designed for optical network automation. The robot demonstrates the capability of direct fiber switching, establishing static fiber links that consume zero power and have minimal insertion loss from fiber connectors. As a precautionary measure before physically switching fiber cables, the robot performs path verification by detecting robot-driven events using real-time coherent receivers, aiming to avoid accidental unplugging. Additionally, the robot showcases its mobility by efficiently navigating between different network racks and rooms while executing various tasks. Implementing the automation of network operations using robots has the potential to reduce both capital and operational expenditures.

An Ultra-Selective OLR – based Microstrip Diplexer with Minimal Insertion Loss for Wireless Communication System

An Ultra-Selective OLR – based Microstrip Diplexer with Minimal Insertion Loss for Wireless Communication System

Polymer-based three-waveguide polarization beam splitter with reduced crosstalk for optical circuitry

Polarization beam splitters are pivotal in manipulating polarized light within photonic integrated circuits for various optical applications. This study introduces a single-mode polarization beam splitter comprising three waveguides realized with polymer materials. The device optimization process employed the beam propagation method, explicitly using the RSoft CAD BeamProp solver. Our proposed beam splitter performs exceptionally well with 99% complete and null light transmission efficiency. In particular, it demonstrates minimal insertion loss (0.04 dB for complete transmission and 0.07 dB for null transmission) and low coupling loss (0.03 dB and 0.04 dB for complete transmission, 21.9 dB and 36.3 dB for null transmission from input to bridge and bridge to output waveguides, respectively). Additionally, the beam splitter showcases significantly reduced crosstalk: −27dB and −26.98dB for TE modes during complete light transfer, and −36.28dB and −33.61dB for TM modes during null light transfer. These results underscore its potential for advancing integrated optical systems.

A New 1 Bit Electronically Reconfigurable Transmitarray

This article proposes a novel 1 bit electronically reconfigurable transmitarray, designed to facilitate digital two-dimensional beam scanning, boasting both high gain and a slim profile. The fundamental phase shifting unit of the transmitarray unit cell consists of a resonant cavity composed of a pair of orthogonal metal gates and dielectric layers, with a cross-sectional height of 0.17 λ. The middle layer of the phase-shifting unit is composed of circular gaps and C-shaped patches, and two diodes with opposite directions are loaded. By turning the diodes ON and OFF, current reversal is accomplished, allowing the unit to transition between its 0 and 1 states and achieve transmission-phase quantization. The unit’s minimal insertion loss is 0.37 dB in state 0 and 0.35 dB in state 1, respectively. In order to verify our design, we designed and processed a 16 × 16 transmitarray in the C-band. The simulated results are consistent with the experimental results. The experimental results show that the transmitarray can achieve ± 45° beam scanning on both the E-plane and H-plane, and the maximum gain is 20.59 dBi at 5 GHz, with an aperture efficiency of 20.5%.

Real-time tunable notched waveguide based on voltage controllable ferroelectric resonator.

In the present study, we have devised and conducted an investigation into a real-time tunable notched waveguide, employing a voltage-controllable plasmonic resonator. This plasmonic resonator is meticulously engineered from a ferroelectric substrate featuring a compound multilayer structure, thereby conferring it with the remarkable capability of flexible permittivity control. Furthermore, we have implemented two non-intersecting Archimedean spiral electrodes on the surface of the ferroelectric substrate, dedicated to applying the bias field onto the controllable plasmonic ferroelectric resonator (CPFR). Notably, our system affords the capability to finely tune both the magnetic and electric modes, achieving precise adjustments of 8.7% and 11%, respectively. The performance is complemented by minimal insertion loss, rapid response times, and a broad range of potential applications, positioning it as a candidate for a diverse array of notched waveguide scenarios.

Incorporating surfactants into PCL microneedles for sustained release of a hydrophilic model drug

Polymeric microneedles (MNs) are widely used for sustained drug release due to their distinct advantages over other types of MNs. Poly-ε-caprolactone (PCL) stands out as a biodegradable and biocompatible hydrophobic polymer commonly employed in drug delivery applications. This study explores the impact of surfactants on the encapsulation and release rate of a model hydrophilic drug, minoxidil (MXD), from PCL MNs. Three nonionic surfactants, Tween 80, Span 60, and polyethylene glycol (PEG), were integrated into PCL MNs at varying concentrations. Compared to the other types of surfactants, PEG-containing PCL MNs exhibit enhanced insertion capabilities into a skin-simulant parafilm model and increased mechanical strength, suggesting facile penetration into the stratum corneum. Furthermore, MXD-PEG MNs show the highest encapsulation efficiency and are further characterized using FTIR, DSC and XRD. Their mechanical strength against different static forces was measured. The MNs exhibit a sustained release pattern over 20 days. Eventually, MXD-PEG MNs were subjected to penetration testing using chicken skin and required minimal insertion forces with no observed MN failure during experimentation even after compression with the maximum force applied (32 N per patch). Taken together, the present work demonstrates the feasibility of incorporating nonionic surfactants like PEG into the tips of hydrophobic PCL MNs for sustained delivery of a model hydrophilic drug. This formulation strategy can be used to improve patient compliance by allowing self-administration and achieving prolonged drug release.

Compact simply-connected SOI spot size converters for TE and TM polarizations

Spot size converters (SSCs) are pivotal building blocks of silicon on insulator (SOI) on-chip optical systems, which enable efficient coupling of modes between waveguides of different widths. In this paper, we propose two SSCs for TE and TM polarizations based on level-set and adjoint methods, which can convert modes between 0.5 µm and 10 µm wide waveguides. The devices’ lengths are 22.4 µm and 23.7 µm, respectively, with simply-connected structures and the 200 nm minimum feature size. The simulation results demonstrate minimal insertion losses of 0.04 dB and 0.12 dB for the two SSCs, with respective 1 dB bandwidths exceeding 170 nm and 250 nm. Within the wavelength range of 1520–1590 nm, the insertion losses are below 0.42 dB and 0.24 dB. Experimental results, normalized with a referenced 250 µm length adiabatic linear taper, indicates insertion losses of less than dB and dB within the 1520–1590 nm wavelength range for the proposed SSCs, demonstrating a ten-fold reduction in length while maintaining comparable performance to the reference taper. Our devices hold the potential to facilitate the utilization of grating couplers in high-efficiency and high integration applications.

Nonreciprocal reflection based on asymmetric graphene metasurfaces.

We propose a scheme to achieve controllable nonreciprocal behavior in asymmetric graphene metasurfaces composed of a continuous graphene sheet and a poly crystalline silicon slab with periodic grooves of varying depths on each side. The proposed structure exhibits completely asymmetric reflection in opposite directions in the near-infrared range, which is attributed to the pronounced structural asymmetry and its accompanying nonlinear effects. The obtained nonreciprocal reflection ratio, reaching an impressive value of 21.27 dB, combined with a minimal insertion loss of just -0.76 dB, highlights the remarkable level of nonreciprocal efficiency achieved by this design compared to others in its category. More importantly, the proposed design can achieve dynamic tunability by controlling the incident field intensity and the graphene Fermi level. Our design highlights a potential means for creating miniaturized and integratable nonreciprocal optical components in reflection mode, which can promote the development of the integrated isolators, optical logic circuits, and bias-free nonreciprocal photonics.

Antiresonant hollow-core fiber Bragg grating design.

Fiber Bragg gratings (FBGs) inscribed in hollow-core fibers hold a potential to revolutionize the field of gas photonics by enhancing the performance and versatility of hollow-core fiber-based matter cells. By effectively transforming these cells into cavities, FBGs can significantly extend the effective length of light-matter interactions. Traditional FBG inscription methods cannot be extended to hollow-core fibers, because light in the fundamental mode is predominantly confined to the hollow region where an index change cannot be induced. In this Letter, we propose a bi-thickness dual-ring hollow-core antiresonant fiber (DRHCF) design that achieves substantial overlap between the fundamental mode and cladding glass in a well-controlled manner, ensuring a strong FBG response with a minimal insertion loss. Through detailed numerical investigations, we demonstrate the feasibility of creating a high reflection FBG in the DRHCF using standard FBG inscription techniques. The proposed device is expected to have a length of <1 cm and the insertion loss of <0.3 dB, including splice loss.

Air-filled SIW technology for mass-manufacturable and energy-efficient terahertz systems

To accommodate the ever-growing data requirements in densely populated areas and address the need for high-resolution sensing in diverse next-generation applications, there is a noticeable trend towards utilizing large unallocated frequency bands above 100 GHz. To overcome the harsh propagation conditions, large-scale antenna arrays are crucial and urge the need for cost-effective, mass-manufacturable technologies. A dedicated Any-Layer High Density Interconnect PCB technology for highly efficient wireless D-band (110–170 GHz) systems is proposed. Specifically, the adapted stack accommodates broadband air-filled substrate-integrated-waveguide components for efficient long-range signal distribution and low-loss passives. The viability of the suggested technology platform is demonstrated by designing, fabricating and measuring several essential low-loss air-filled substrate-integrated-waveguide components, such as a dual rectangular filter, with a minimal insertion loss of 0.87 dB and 10 dB-matching within the (132.8–139.2 GHz) frequency band, and an air-filled waveguide with a routing loss of only 0.08 dB/mm and a flat amplitude variation within 0.01 dB/mm over the (115–155 GHz) frequency range. A broadband transition towards stripline, with a limited loss of 1.1 dB, is described to interface these waveguides with compactly integrated chips. A tolerance analysis is included as well as a comparison to the state of the art.