Silicon Ring Research Articles

The structural and electronic configuration of an amorphous silica surface, from its liquid to glassy state

Through classical molecular dynamics computational simulations, the surface of amorphous silica (vitreous silica) was generated for a system comprising 64 SiO2 molecules (192 atoms) via the classical three-body glass potential. Starting from the liquid state of silica at 3400 K, it was cooled in three different ways at intervals of 200, 400, and 2000 K, with a cooling rate of 4.4 K/ps and establishing relaxation at intermediate temperatures, yielding three groups of surfaces from 3400 to 1400 K. Subsequently, these systems underwent sudden cooling from 1400 to 300 K via the Andersen and Nosé‒Hoover thermostats, followed by relaxation at 300 K via a microcanonical ensemble (NVE constant). Each surface that underwent relaxation was analyzed through ab initio molecular dynamics for the following three physical properties, which are temperature dependent. The average electric charges of oxygen and silicon. Microstructures on the outermost part of the surface were observed and comprised nonbridging oxygen atoms, undercoordinated silicon, and N-membered rings (3 ≤ N ≤ 5). The radial distribution functions were analyzed for all surfaces. Below 2000 K, a type of freezing is observed in all the structures because of the glass transition. All analyses were performed at zero pressure.

Manipulating the Substituent Sphere of a Bicyclic Silicon(I) Ring Compound Results in Anionic Cubane-Type Clusters and a Tetrahedral Silanide.

The reaction of the bicyclic silicon(I) ring compound Si4{N(SiMe3)Mes}4 1 with strong zwitterionic character and moderate sterical demand of the amido substituents with two equivalents of KC8 was investigated. This resulted in the unexpected abstraction of two amido substituents from 1 and additionally in dimerization to a dianionic Si8 cluster compound 2 with four unsubstituted silicon atoms and two [K([18]crown-6)]+ counter cations. Performing this reaction in the absence of [18]crown-6 results in release of only one amido substituent from 1 and dimerization to a dianionic Si8 cluster compound 3 with only two unsubstituted silicon atoms. This reaction with KC8 was repeated and trapping agents such as SiMe3Cl and tBuCl were added in-situ whereupon the second isolated homocyclic silylene 4 and a monoanionic hydride and tBu substituted Si8 cluster 5 with one unsubstituted silicon atom were isolated. Furthermore, 1 was reacted with KOtBu which resulted in the selective abstraction of one SiMe3 group and formation of the tetrahedral silanide 6 with one imido substituent bridging an edge of the tetrahedron.

Hybrid Fibers with Subwavelength-Scale Liquid Core for Highly Sensitive Sensing and Enhanced Nonlinearity.

Interest grows in designing silicon-on-insulator slot waveguides to trap optical fields in subwavelength-scale slots and developing their optofluidic devices. However, it is worth noting that the inherent limitations of the waveguide structures may result in high optical losses and short optical paths, which challenge the device's performance in optofluidics. Incorporating the planar silicon-based slot waveguide concept into a silica-based hollow-core fiber can provide a perfect solution to realize an efficient optofluidic waveguide. Here, we propose a subwavelength-scale liquid-core hybrid fiber (LCHF), where the core is filled with carbon disulfide and surrounded by a silicon ring in a silica background. The waveguide properties and the Stimulated Raman Scattering (SRS) effect in the LCHF are investigated. The fraction of power inside the core of 56.3% allows for improved sensitivity in optical sensing, while the modal Raman gain of 23.60 m-1·W-1 is two times larger than that generated around a nanofiber with the interaction between the evanescent optical field and the surrounding Raman media benzene-methanol, which enables a significant low-threshold SRS effect. Moreover, this in-fiber structure features compactness, robustness, flexibility, ease of implementation in both trace sample consumption and reasonable liquid filling duration, as well as compatibility with optical fiber systems. The detailed analyses of the properties and utilizations of the LCHF suggest a promising in-fiber optofluidic platform, which provides a novel insight into optofluidic devices, optical sensing, nonlinear optics, etc.

Hyperelastic material models for simulating deformation of silicone ring pessaries

Pessaries are removable gynecological prosthetic devices that provide mechanical support for temporary or long-term symptom relief of pelvic floor disorders, such as pelvic organ prolapse and stress urinary incontinence. To date, limited mechanical tests have been performed on physical pessary designs to characterize their behaviour under load; however, custom pessary manufacturing is expensive and time consuming. As an alternative, finite element (FE) modeling can provide detailed numerical insight into the response of a pessary design under load but to date has seen limited application, with little data available for pessary silicone materials. This study aimed to identify hyperelastic material models for two silicone materials used in custom pessary cocoon moulded manufacturing towards FE analysis of ring with support (RWS) pessaries. It was hypothesized that hyperelastic material models could be identified to capture the force and deformation response of multiple RWS sizes under different boundary conditions and silicone materials (Shore 60A and 40A). To understand the material characteristics of pessary silicone, uniaxial tension and compression tests were performed then the experimental data was fit with Mooney-Rivlin (MR) material models. To ensure the material models characterize the pessary behaviour, data from mechanical tests representing the RWS pessary folding and modified 3-point bending were compared to FE recreations (FEBio) of the same tests with the MR materials applied to the pessaries. The FE model results demonstrated good agreement in the force-displacement response for the fold and 3-point bending models for different pessary sizes and silicone stiffnesses. This work demonstrates the hyperelastic material models’ efficacy and will enable future studies to improve biomechanical analysis of silicone pessary designs.

Gastrogastric Intussusception 10 Years After Laparoscopic Gastric Greater Curvature Plication: a Case Report

The use of a nonadjustable silicone band around the gastric pouch of Rouxen-Y gastric bypass (RYGB) to reduce the recurrence of obesity is still being debated in the literature. The primary objective of this study was to evaluate banded and non-banded RYGB regarding % total weight loss (%TWL) and complications up to 10years postoperatively and regarding the removal rate of the silicone band. A retrospective study of the medical records of all patients submitted to banded and non-banded RYGB between 2000 and 2020 was conducted. Clinical data (age, gender, weight, body mass index-BMI, comorbidities, %TWL, and the prevalence of vomiting) and laboratory data (hemoglobin, serum iron, albumin, and vitamin B12) were obtained preoperatively and at six months, 1, 2, 3, 5, 7, and 10years for both groups and at 12, 15, and 20years after banded RYGB. In total, 858 patients underwent RYGB: 409 underwent banded RYGB and 449 underwent non-banded RYGB. In the preoperative period, banded RYGB patients were heavier and had higher rates of hypertension and dyslipidemia. The %TWL was higher in the banded RYGB group up to 7years. The prevalence of vomiting is much higher in this group, which also had lower laboratory test values. Of the banded RYGB patients, 9.53% had to have the silicone ring removed after presenting complications. Banded RYGB promotes significantly higher rates of TWL at the expense of a higher frequency of vomiting.

A High-Speed Silicon Ring Modulator with a Large Working Wavelength Range

With the advantages of high speed, small size, and easy integration, the silicon photonic resonant ring modulator has gradually become a critical device for emerging integrated optical platforms. Ring modulators are primarily used in optical communications, optical computing, artificial intelligence, and other fields. In this work, the proposed ring modulator can operate in both the O- and C-bands. The 3 dB electro-optical (EO) bandwidth of the ring modulator is 39 GHz and 34 GHz at −4 V in the O-band and C-band, respectively. The modulation efficiency of the device is 0.92 V·cm and 0.95 V·cm in the O-band and C-band, respectively. The eye diagram of an optical output signal from the device is tested using a 100 Gbit/s non-return-to-zero (NRZ) input signal with a 2.5 Vpp in both the O-band and C-band. The modulation speed can reach 140 Gb/s and 120 Gb/s in the O-band and C-band with four-level pulse amplitude modulation (PAM-4) formats at a voltage swing of 2.5 Vpp, respectively.

Theoretical evaluation of M/H-magadiite and Al modified M/H-[Al]-magadiites single-atom catalysts (M = Ag, Au, Pd, and Pt)

This work intends to simulate the interaction of metal single-atom(s) supported on surfaces of H-magadiite (H4Si14O30) and Al substituted H-[Al]-magadiites (H5AlSi13O30), hereafter called M/H-magadiite and M/H-[Al]-magadiite (M = Ag, Au, Pt, Pd), using DFT calculations (PBE and PBE-D3 functionals). Three distinct positions were defined in all surfaces to optimize each simulated model: “hydroxyl”, “edge” and “cavity”. The Au/H-magadiite and Ag/H-magadiite models were more stable at the “hydroxyl” sites. Meanwhile, in the aluminated surfaces, the presence of an extra hydrogen atom (here called Hextra, located in the “edge” region) was responsible for a more stable situation of these metal atoms. On the other hand, the Pd and Pt single-atoms present in H-magadiite and H-[Al]-magadiites showed greater interaction with all the sites, compared to the Au- and Ag- models. Based on the binding energies and other electronic calculations, the aluminol site at H-[Al]-magadiites has the best capacity to support metal species. For example, the Pt/H-[Al]-magadiite showed the lowest binding energy (-2.64 eV for PBE and -2.93 eV for PBE-D3), the strongest charge interaction and the smallest Pt – Hextra distance (1.55 Å). The migration barriers (PBE) in Ag/H-magadiite, Au/H-magadiite, and Pd/H-magadiite were lower than 21.50 kJ·mol−1, suggesting the high possibility of metal sintering. For all the cases, the PBE-D3 overestimated the barriers. Contrarily, the Pt/H-magadiite structures stabilized in the “cavity” region, inside the silicon rings of the silicate, and presented a migration barrier greater than 200 kJ·mol−1. These calculations offered the first indications of the behavior of single-atoms, which will serve as the basis for a broader description, in future works, of the migration of metal species in the Al-models simulated here, as well as for modeling single-atom catalysts that can be used in stable conditions.

Long-term Comparative Evaluation of Weight Loss and Complications of Banded and Non-banded Roux-en-Y Gastric Bypass.

The use of a nonadjustable silicone band around the gastric pouch of Roux-en-Y gastric bypass (RYGB) to reduce the recurrence of obesity is still being debated in the literature. The primary objective of this study was to evaluate banded and non-banded RYGB regarding % total weight loss (%TWL) and complications up to 10years postoperatively and regarding the removal rate of the silicone band. A retrospective study of the medical records of all patients submitted to banded and non-banded RYGB between 2000 and 2020 was conducted. Clinical data (age, gender, weight, body mass index-BMI, comorbidities, %TWL, and the prevalence of vomiting) and laboratory data (hemoglobin, serum iron, albumin, and vitamin B12) were obtained preoperatively and at 6months, 1, 2, 3, 5, 7, and 10years for both groups and at 12, 15, and 20years after banded RYGB. In total, 858 patients underwent RYGB: 409 underwent banded RYGB and 449 underwent non-banded RYGB. In the preoperative period, banded RYGB patients were heavier and had higher rates of hypertension and dyslipidemia. The %TWL was higher in the banded RYGB group up to 7years. The prevalence of vomiting is much higher in this group, which also had lower laboratory test values. Of the banded RYGB patients, 9.53% had to have the silicone ring removed after presenting complications. Banded RYGB promotes significantly higher rates of TWL at the expense of a higher frequency of food intolerance and vomiting.

Dual port high gain frequency reconfigurable THz graphene–silicon ring ceramic antenna with polarization and pattern diversity features

Dual port high gain frequency reconfigurable THz graphene–silicon ring ceramic antenna with polarization and pattern diversity features

All-Silicon Polarization-Insensitive Metamaterial Absorber in the Terahertz Range.

All-silicon terahertz absorbers have attracted considerable interest. We present a design and numerical study of an all-silicon polarization-insensitive terahertz metamaterial absorber. The meta-atoms of the metamaterial absorber are square silicon rings which can be viewed as gratings. By properly optimizing the structure of the meta-atom, we achieve a broadband absorptivity that is above 90% ranging from 0.77 THz to 2.53 THz, with a relative bandwidth of 106.7%. Impedance matching reduces the reflection of the terahertz waves and the (0, ±1)-order diffraction induce the strong absorption. The absorption of this absorber is insensitive to the polarization of the terahertz wave and has a large incident angle tolerance of up to 60 degrees. The all-silicon metamaterial absorber proposed here provides an effective way to obtain broadband absorption in the terahertz regime. Metamaterial absorbers have outstanding applications in terahertz communication and imaging.

Strong field enhancement and ultra-narrow linewidth based on the coupling of anapole/gap modes in silicon nanodimer-ring arrays

All-dielectric metamaterials have recently received significant attention in the field of nanophotonics, due to their negligible dissipative losses and strong polariton response compared with metallic metamaterials. However, simultaneously achieving an ultra-narrow resonance linewidth and a significant field enhancement in the all-dielectric metamaterials is still a great challenge, limiting their further practical application. In this work, a novel nanostructure composed of silicon ring and nanodimer arrays is theoretically proposed and numerically simulated. Through introducing the coupling between the anapole mode originating from the ring arrays and the gap mode deriving from the nanodimer arrays, the as-designed dielectric metamaterial manifests dual-band high-quality resonance characteristics with strong electric field enhancement reaching up to 300 times, an ultra-narrow linewidth as narrow as 0.35 nm, and a large Q-factor of 4223.43 synchronously. Benefiting from the exceptional optical spectral characteristics, the proposed dielectric nanodimer-ring metamaterial can work as a high-available refractive index sensor, whose sensitivity can reach 307.69 nm RIU−1 with its figure of merit attaining 879.11 RIU−1, efficiently distinguishing an index change of less than 0.01. This research opens up a promising path for achieving extremely narrow spectral linewidth and significant enhancement of the electric field, exhibiting immense possibilities in applications such as biochemical sensing, nonlinear optics, and surface enhanced spectroscopy.

Universal silicon ring resonator for error-free transmission links

We report the design, fabrication, and characterization of a universal silicon PN junction ring resonator for C band error-free communication links operated up to 50 Gb/s with co-designed optical modulation and detection performance. The universal p-n junction ring device shows co-designed detection responsivity up to 0.84 A/W, in conjunction with a modulation efficiency of ∼4 V·mm and >8 dB optical modulation extinction ratio, enabling C band 50 Gb/s NRZ communication link with a bit error rate ≤3×10−12. Individually, the speed of modulation and detection is measured up to 112 Gb/s and 80 Gb/s, respectively. The principle of co-designing the PN junction ring modulator and detector performance required for error-free communication links can significantly ease the fabrication yield challenges of ring structures by reducing the number of types of devices. The principle can also be applied to O band wavelengths. To the best of our knowledge, for the first time, a device of this type has achieved both error-free modulation and detection operation up to 50 Gb/s in the C band individually or in conjugation as an error-free communication link, which paves the way to realize a >1.6 Tb/s all-silicon WDM-based error-free optical transceiver link in the future and is essential for future programmable photonics circuits.

Convincing 10-Year Follow-up Results of the Banded Roux-en-Y Gastric Bypass

IntroductionSeveral studies have shown the positive effect on weight loss of the banded Roux-en-Y gastric bypass (BRYGB). Thus far, studies describing the 10-year post-operative results are scarce. Therefore, the aim of this study was to describe the weight loss results, effect on associated medical problems, and complication rates during 10 years of follow-up after BRYGB.MethodData were collected from patients who underwent laparoscopic BRYGB with a non-adjustable silicone gastric ring between January 2011 and March 2013. All patients were included when found to be eligible according to the IFSO criteria.ResultsOne hundred forty-nine patients were included, 110 received a primary BRYGB and 39 received a conversional BRYGB. The primary BRYGB group consisted of 68% female patients with a mean BMI of 44.5 kg/m2 and a mean age of 46 years old. The conversional group consisted of 77% females and had a mean BMI of 34.8 kg/m2 and a mean age of 48 years. At 10-year follow-up, 67.1% of the data was available. Ten-year post-operative 30% total weight loss was seen in the primary group, and 7% in the conversional group. In 10 years, 23% of the patients had complications of which half were ring-related.ConclusionThe addition of a silicon ring to the Roux-en-Y gastric bypass may result in substantial and stable weight loss maintenance 10 years post-operative. Furthermore, the number of patients with long-term complications was low and the number of associated medical problems was significantly reduced.Graphical

Design and Study the Performance of a CMOS-Based Ring Oscillator Architecture for 5G Mobile Communication

Oscillator circuits are used to make accurate and reliable clock signals for systems as simple as a wristwatch and as complicated as satellites, which are important for long-distance communication. There are many ways to build an oscillator circuit, using either passive or active parts. Each option has pros and cons, but at the current level of mobile communication development, the most important things are interoperability and low power use. This need has driven the development of compact, battery-operated electronics, and Very Large-Scale Integration (VLSI)-based ring oscillators provide the ideal solution. These oscillators ought to dissipate less power, have a large tuning range, and be compact. The paper presents a novel Complementary Metal Oxide Silicon (CMOS) ring oscillator that serves as a Voltage Controlled Oscillator. The suggested architecture utilizes the advantages of both a current-starved ring oscillator and a negative-skewed delay by combining their constituent parts. The proposed architecture has a control voltage of 1.15 V and a supply voltage of 2 V, generating a 9.35 GHz dominant frequency with a 13.82% harmonic distortion between the inputs and outputs. The proposed architecture can implement 5G-based applications that require high frequency and low power by carefully selecting the passive components within the design. Doi: 10.28991/ESJ-2024-08-01-020 Full Text: PDF

Clock gene Per2 modulates epidermal tissue repair in vivo.

Wound healing can be influenced by genes that control the circadian cycle, including Per2and BMAL1, which coordinate the functions of several organs, including the skin. The aim of the study was to evaluate the role of PER2 during experimental skin wound healing. Two groups (control and Per2-KO), consisting of 14 male mice each, were anesthetized by inhalation, and two 6 mm wounds were created on their dorsal skin using a punch biopsy. A silicone ring was sutured around the wound perimeter to restrict contraction. The wound healing process was clinically measured daily (closure index) until complete wound repair. On Day 6, histomorphometric analysis was performed using the length and thickness of the epithelial migration tongue, in addition to counting vessels underlying the lesion by immunofluorescence assay and maturation of collagen fibers through picrosirius staining. Bromodeoxyuridine(BrdU) incorporation and quantification were performed using the subcutaneous injection technique 2 h before euthanasia and through immunohistochemical analysis of the proliferative index. In addition, the qualitative analysis of myofibroblasts and periostin distribution in connective tissue was performed by immunofluorescence. Statistically significant differences were observed in the healing time between the experimental groups (means: 15.5 days for control mice and 13.5 days for Per2-KO; p = 0.001). The accelerated healing observed in the Per2-KO group (p < 0.05) was accompanied by statistical differences in wound diameter and length of the migrating epithelial tongue (p = 0.01) compared to the control group. Regarding BrdU immunoreactivity, higher expression was observed in the intact epithelium of Per2-KO animals (p = 0.01), and this difference compared to control was also present, to a lesser extent, at the wound site (p = 0.03). Immunofluorescence in the connective tissue underlying the wound showed a higher angiogenic potential in the Per2-KO group in the intact tissue area and the wound region (p < 0.01), where increased expression of myofibroblasts was also observed. Qualitative analysis revealed the distribution of periostin protein and collagen fibers in the connective tissue underlying the wound, with greater organization and maturation during the analyzed period. Our research showed that the absence of the Per2 gene positively impacts the healing time of the skin in vivo.This acceleration depends on the increase of epithelial proliferative and angiogenic capacity of cells carrying the Per2 deletion.

Quantum interference of pulsed time-bin entanglement generated from silicon ring resonator

We demonstrate a pulsed operation of an entangled photon pair source that is based on a silicon ring resonator. Time-bin entangled photon pairs at telecommunication wavelengths are generated via spontaneous four-wave mixing, which is excited by a pulsed pump laser. The entanglement between the generated photon pair is analyzed by using asymmetric Mach–Zehnder interferometers followed by single-photon detectors, resulting in non-classical interference with a visibility exceeding a classical limit. The reason for the degradation of the interference visibility is discussed using the theoretical model with experimental parameters. Our experimental results show successful pulsed generation of entanglement, which represents an important step towards a synchronized quantum network based on silicon photonics.

Silicon ring resonator with ZIF-8/PDMS cladding for sensing dissolved CO2 gas in perfluorocarbon solutions

Precise measurement of dissolved CO2 gas concentration in perfluorocarbon (PFC) solution is essential to the implementation and understanding of extra-pulmonary gas exchange with liquid ventilation. While electrochemical and optochemical sensing methods are widely used for dissolved CO2 sensing in aqueous solution, dissolved CO2 sensing in the PFC solution remains largely unexplored. We report a refractive index-based silicon photonic sensor for monitoring dissolved CO2 gas in the PFC solution. The sensor employs a high-Q silicon ring resonator with ZIF-8 cladding for selective and sensitive detection of dissolved CO2 gas. Further, a gas-permeable PDMS coating layer is applied to the ZIF-8 cladding for enabling gas diffusion between the PFC solution and the ZIF-8. The PDMS layer does not dissolve in PFC and its hydrophobic properties help protect the ZIF-8 from potential damage caused by aqueous body fluids in the PFC solution during the liquid ventilation process. The fabricated sensor exhibits stable and repeatable responses in the PFC solution with a fine resolution of ∼0.16 CO2 vol%, good selectivity for dissolved CO2 over dissolved O2, and a fast response time of ∼1.9 min, enabling reliable monitoring of dissolved CO2 gas level changes in the PFC solution.

O-band Silicon Ring Modulators with Highly Efficient Electro- and Thermo-Optic Modulation

O-band Silicon Ring Modulators with Highly Efficient Electro- and Thermo-Optic Modulation

A study of traction endoscopic submucosal dissection using a unique traction device with a ring and a clip with an obtuse tip.

Appropriate use of traction devices is important in Endoscopic Submucosal Dissection (ESD). The Sure-Clip Traction Band (Microtec: "traction band") is a disposable clip with a series of three small silicone rings, which can be used as a traction device by inserting the clip through two holes. The SB clip long with a 125-degree tip claw angle (SB Kawasumi: hereafter referred to as SB clip) has an obtuse angle tip, can be re-gripped and is considered to cause less damage to the digestive tract wall when withdrawn after clipping. We performed traction ESD using a traction band and SB clip. These were used for gastric ESD in 4 cases and colorectal ESD in 3 cases.

Silicon Chalcogenide Cage Compounds: New Structures Derived from the Bicyclic Silicon(I) Ring Compound Si4 {N(SiMe3 )Mes}4.

The bicyclic silicon(I) ring compound Si4 {N(SiMe3 )Mes}4 (2) was used as starting material in reactions with chalcogens and chalcogen transfer agents at low temperatures. This resulted in the selective formation of new cage compounds. With Me3 NO, a silicon oxide with adamantane-type cage 3 was isolated that represents the first isolated T4 silsesquioxane. Reactions with propylenesulfide and red selenium gave direct access to defect heterocubane-type cages 4 and 5 with three Si-Si bonds wherein the silicon atoms adopt different low oxidation states of +I and +III. A reaction with elemental tellurium even occurs below room temperature to provide ditelluro-tetrasila-tricyclohexane 6.