Metal Disk Research Articles

Atmospheric Plasma Sources as Potential Tools for Surface and Hand Disinfection

Good hand hygiene has proven to be essential in reducing the uncontrolled spread of human pathogens. Cold atmospheric plasma (CAP) may provide an alternative to disinfecting hands with ethanol-based handrubs when handwashing facilities are unavailable. CAP can be safely applied to the skin if the energy is well controlled. In this study, radio frequency (RF) and direct current (DC) plasma sources were built with a pin-to-mesh electrodes configuration inside a fused silica tube with a 5 mm inner diameter. Microbiological assays based on EN 13697:2015+A1:2019 using Escherichia coli DSM 682 or Staphylococcus epidermidis DSM 20044 were used to examine the antimicrobial effect of various plasma conditions. Metal and silicone disks that model skin were used as inoculation matrices. The prototype air RF CAP achieved significant disinfection in the MHz range on stainless steel and silicone substrates. This is equivalent to half the performance of direct current CAP, which is only effective on conductive substrates. Using only electricity and air CAP could, with further optimization to increase its efficacy, replace or complement current hand disinfection methods, and mitigate the economic burden of public health crises in the future.

Selective plasmonic trapping of nano-particles by Archimedes metalens.

Optical tweezer is a non-invasive method for optical force tool applied in various fields like biology, physics, and lab on chip manipulation. The Archimedean helix shape is ideal for creating chiral nanostructures, and being able to generate plasmonic focused hotspot field for optical trapping. Here we design a metal disk with the Archimedean shape to own the ability of selective trapping nanoparticles based on the spin-orbit interactions with circularly polarized light. The plasmonic near field on the metalens can be designed by adjusting the geometric parameter flexibly. We numerically analyze the optimal size and screw pitch of the metal disk to realize the switch modulation of hotspot generation, and then demonstrate the novel switchable optical trapping ability in the view of optical force and potential well analysis under the circularly polarized light excitation by a 532 nm laser. The work shows significant potential for on-chip optical trapping in various fields.

Design of Ka‐band, broadband, omnidirectional, with a top metal disk antenna

AbstractIn this report, a Ka‐band, broadband, omnidirectional, with a top metal disk antenna is proposed. The antenna is fed by an air waveguide. The TE10 mode of the waveguide can efficiently be converted into an air coaxial TEM mode by a compact waveguide air coaxial transition. After matching and adjusting, the dielectric substrate is loaded and then transited to the metal radiation structure loaded with a top metal disc to obtain omnidirectional electromagnetic waves efficiently converted to free space. By optimizing the sizes of waveguide to air‐coaxial transition structure and disk, and so on, a good broadband omnidirectional antenna performance is finally achieved. The measured fractional impedance bandwidth is larger than 30% with the reference of S11 dB, which fully verifies the rationality of the design. In addition, measured patterns at the plane of different azimuth angles almost coincide with each other, which shows an excellent omnidirectional pattern.

Low-Profile Ultra-Wideband Dual-Polarized Omnidirectional Antenna for Indoor Base Station

A low-profile ultra-wideband omnidirectional antenna with dual polarizations for indoor mobile communication is presented. The horizontally polarized (HP) omnidirectional element is introduced by using twelve I-shaped slot antennas, which are arranged in a circle-shaped array and excited by a 1-to-12 power divider. The vertically polarized (VP) omnidirectional performance is introduced by using a dual-M-shaped monopole with a small ground plane. To enhance the impedance matching within an ultra-wide bandwidth, a top metal disk with four chunks, a bottom metal loop and a ring slot embedded in the ground plane are employed for the design of the VP element. After replacing the metal disk of the VP element with the designed HP element, the omnidirectional antenna with dual polarizations is then simply achieved. By utilizing this new method, an ultra-wideband dual-polarized omnidirectional antenna for indoor mobile communications is designed, manufactured and measured. It has an ultra-wide bandwidth of 117% (1.44-5.5 GHz), a high isolation of 30 dB, and a low profile of 0.16λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> (λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> denotes the wavelength at the lowest frequency of the operating band). Good omnidirectional radiation performance with gain variation < 2.6 dBi is obtained for both HP and VP ports over the ultra-wide operating band.

Applicability limits of the DAX test in plastic bonded explosives

The Disc Acceleration eXperiment (DAX) is one of the most recent experimental methods of performance characterization of new energetic materials. A cylindrical explosive charge accelerates a thin metallic disc and its velocity is measured continuously using photonic Doppler velocimetry. The detonation velocity is measured simultaneously. The DAX test can be used to obtain the Chapman-Jouguet (CJ) detonation pressure and to describe detonation products expansion using reduced amount of explosive. A series of DAX tests was performed at various charge diameters and disc thicknesses with Semtex 1 A plastic bonded explosive and sensitized nitromethane. The DAX-like evaluation was also applied to previously measured data of Semtex 1A and A-IX-1 explosives. The optimum disc thickness is determined by the disc to explosive mass ratio of 0.01–0.08. The repeatability of the Semtex 1 A detonation pressure results is about four times lower compared to the pressed and liquid explosives.

Local density of states above a disk—Geometrical vs thermal boundary conditions

We analytically calculate the contribution to the local density of states due to thermal sources in a disk-like patch within the framework of fluctuational electrodynamics. We further introduce a wavevector cutoff method to approximate this contribution. We compare the results obtained with the source and cutoff method with the numerical exact local density of states above a metal disk attained by SCUFF-EM calculations. By this comparison, we highlight the difference and resemblance of thermal and geometrical boundary conditions which are both relevant for near-field scanning microscope measurements. Finally, we give an outlook to general lateral temperature profiles and compare it with surface profiles.

Designs of Corrosion Modules for Long-Term Corrosion Tests of Canister Materials in Aerobic and Anaerobic Underground Water

Corrosion modules simulating the engineered barrier system were designed in this study for long-term-corrosion (LTC) testing of canister materials under aerobic and anaerobic conditions. The LTC module for aerobic conditions was designed as a bath-type container with flowing underground water extracted from the Korea Underground Research Tunnel. Five types of metallic disks, that is, rolled Cu, Type 304 stainless steel (SS), Titanium Grade 2 (Ti-G2), cast iron (CI), and Cu coating, were embedded into bentonite and maintained at different temperatures. After 3 years of testing under aerobic conditions, the corrosion rates of CI and Cu were estimated to be 1.9 μm/year and 550 nm/year, respectively. The SS and Ti-G2 exhibited a better corrosion rate of 6 nm/year. The LTC module for anaerobic conditions was developed in a vessel-type cylindrical container to allow it to settle in the boreholes. Four coin-shaped disks of each metal were embedded in bentonite, which was subsequently stacked in the cylindrical vessel. The vessels were placed in boreholes at a depth of 300 m. The Cu corrosion rate after 6 months of LTC testing under anaerobic conditions was 280 nm/year. Longer LTC tests will provide a more exact corrosion rate.

Multibeam Antenna with a Full Azimuth Field Angle Based on a Layered Metal-Dielectric Cylindrical Lens

A multibeam antenna based on a layered lens with axial symmetry in the form of a set of dielectric disks with a refractive index gradient along the radius, which are located between metal disks, is proposed and investigated. A layered lens converts the fields of feeds located on a circle centered on the axis of the lens in the plane of its base into highly directed beams in the same plane. A synthesis of a layered lens is carried out, the layers of which are made in the form of a set of dielectric rings of variable thickness. The analysis of a multibeam lens antenna with metal-dielectric feeds was carried out by numerical simulation using the finite element method.

Design and manufacturing of fertilizer spreader machine

Indian economy is based on agricultural products. In India, 58% of people are farmers. The most common crops planted by farmers are wheat, rice, corn oil crops, pulses millets, sugarcane, tea coffee, cotton and jute. India produces the majority of the world's sugarcane because of its expanding sugar demand. Our main aim is to reduce the farmer's effort in spreading fertilizer. This paper aims to reduce the human effort in spreading the chemical and dung manure fertilizer on the farm. The fertilizer is dropped through the metallic impeller disc, creating a means for applying chemical and dung manure fertilizer to fallow land. There are three layers to the product design: the top, middle, and bottom. Hopper is on the top level, an impeller disc is in the middle, and tires are on the bottom level. A frame and column support the whole design. The issue with manual fertilizer spreading equipment and the conventional method of fertilization has been resolved by this project. Due to its one-person operation, this machine fulfils the requirements of farmers who are struggling with the rising cost of fertilizer, labour costs, and unavailability of labour. This approach reduces the problems in the spreader models that are currently in use and cuts the time needed for conventional fertilizations by more than half. This approach has some drawbacks, including the inability to be employed in conditions of severe rainfall and when crops are taller than four feet.

Emergent tricriticality in magnetic metamaterials

Metallic discs engineered on the 100 nm scale have an internal magnetic texture which varies from a fully magnetized state to a vortex state with zero moment. The interplay between this internal structure and the inter-disc interactions is studied in magnetic metamaterials made of square arrays of the magnetic discs. The texture is modeled by a mesospin of varying length with O(2) symmetry and the inter-disc interaction by a nearest neighbour coupling between mesospins. The thermodynamic properties of the model are studied numerically and an ordering transition is found which varies from Kosterlitz-Thouless to first order via an apparent tri-critical point. The effective critical exponent characterising the finite size magnetization evolves from the value for the 2D-XY model to less than half this value at the tri-critical point. The consequences for future experiments both in and out of equilibrium are discussed.

The Treasure of Coricancha

This essay ties the return of a pre-Columbian metal disk from the Smithsonian Institution to Peru in 2021 to the sacking of the Inca's principal residence of the sun in Cusco, known as Coricancha, in 1533. The disk's legendary (and un-substantiated) provenance from Cusco is analyzed in light of ongoing yearnings both to extract the hidden treasures of Coricancha and to recover the lost sun deities of Coricancha. The essay reviews the archeological and art historical literature concerning the disk and recommends that the artwork be (re)connected both to the site of Coricancha and to the region of Lake Titicaca.

Experimental investigation of liquid metal droplet flow affected by a time-dependent magnetic field

Abstract The present study investigates experimentally the effects of a time-dependent and spatially inhomogeneous magnetic field on liquid metal droplet flow down an inclined substrate. The flow is solely excited by the electromagnetic interactions between the electrically conducting melt and the applied magnetic field. The metal droplet consists of the eutectic alloy GaInSn which is liquid at room temperature. The magnetic field is generated in the gap between two metallic disks that are equipped with a special geometric arrangement of permanent magnets and put into a measured rotation. During the experiments, a droplet of a measured volume is positioned on an electrically non-conducting substrate that is slightly inclined against the horizontal direction. Droplet and substrate are placed in between the two rotating magnetic disks. In our experiments, we record the electromagnetically excited flow of the droplet downwards onto the substrate using a high-speed camera system. Applying standard techniques of digital image processing, we measure both the displacement position and velocity of the droplet as a function of time. We observe that, depending on the rotation rate of the disks and angle of inclination, the magnetic field eventually triggers this spreading process. In more detail, by evaluating the recorded data, we find that the magnetic field excites capillary waves at the free surface of the droplet. These surface waves contribute to a redistribution of volume towards the contact line formed at the downward-facing end tip of the droplet. This mode of transport steepens the contact angle, allowing the droplet to move. Besides the fundamental aspect of this work, the present study may contribute to the electromagnetic control of both the production of metallic microfibers and metallurgic coating processes as well as to the non-contact electromagnetic flow measurement technique of Lorentz force velocimetry applied to liquid metal free-surface flows.

The Novel Approach of Oil Separator from Sea Water to Prevent Pollution in Ocean

Ocean pollution is the major concern among all types of pollution. Oil floats on water and moves over aluminium discs considerably more slowly than water does throughout work because oil has a higher viscosity than water. This makes it easier to separate the water and oil. The objective of the present study is to design and develop the oil separator model in order to prevent pollution in ocean. The viscosity difference is the basic inspiration for this research. Oil floats on the surface because water is denser than oil. The qualities of this oil and water provide the foundation for this oil separation operation. The model uses four metal discs connected to a motor shaft to speed up the process of separating oil from water. The 12V DC battery powers the motor. The methods for recovering oil that were previously employed were ineffective and severely damaging to the environment. Burning any oil that had leaked onto the water was one of the most popular techniques. It produces a lot of harmful chemicals, such carbon monoxide (CO) and carbon dioxide (CO2) which is harmful for marine life. The results show that in order to utilise this oil, the oil separator model recovers around 85–90% of the oil, and produces no pollution.

Antibacterial Surgical Sutures Developed Using Electrostatic Yarn Wrapping Technology.

A significant amount of research has been conducted on applying functional materials as surgical sutures. Therefore, research on how to solve the shortcomings of surgical sutures through available materials has been given increasing attention. In this study, hydroxypropyl cellulose (HPC)/PVP/zinc acetate nanofibers were coated on absorbable collagen sutures using an electrostatic yarn winding technique. The metal disk of an electrostatic yarn spinning machine gathers nanofibers between two needles with positive and negative charges. By adjusting the positive and negative voltage, the liquid in the spinneret is stretched into fibers. The selected materials are toxicity free and have high biocompatibility. Test results indicate that the nanofiber membrane comprises evenly formed nanofibers despite the presence of zinc acetate. In addition, zinc acetate can effectively kill 99.9% of E. coli and S. aureus. Cell assay results indicate that HPC/PVP/Zn nanofiber membranes are not toxic; moreover, they improve cell adhesion, suggesting that the absorbable collagen surgical suture is profoundly wrapped in a nanofiber membrane that exerts antibacterial efficacy and reduces inflammation, thus providing a suitable environment for cell growth. The employment of electrostatic yarn wrapping technology is proven effective in providing surgical sutures with antibacterial efficacy and a more flexible range of functions.

Double broadband enhanced absorber based on graphene-coupled metal disk resonator structure

A double broadband terahertz absorber based on nonstructured graphene with a dielectric coupled gold disk structure was investigated in this paper. The results show that one absorption band can be switched from reflection state (“OFF”) to absorption state (“ON”), and the other absorption band can be switched from reflection state (“OFF”) to absorption state (“ON”), with bandwidths of over 90% absorption ranging from 0.46 to 1.4 THz and 2.38 to 3.35 THz, respectively. Furthermore, the double broadband terahertz absorber has polarization and background refractive index insensitivity. The Fabry Perot resonance between the graphene sheet and the bottom gold reflector is primarily responsible for the double broadband absorption in graphene, which can be enhanced by the addition of a gold disk resonator. Because of the aforementioned properties, the proposed absorber has potential applications in multiple optical switches, terahertz photoelectric detectors, modulators, and sensors.

Broadband terahertz absorber based on the coupling between Au and graphene

A simply designed broadband meta-absorber (MA) that works in terahertz (THz) band is proposed and investigated. The reflector substrate of the MA is composed of nickel. The middle layer of this structure is made of dielectric Al2O3, which serves as a dielectric layer between the nickel and the metasurface layer. The metasurface layer comprises a graphene ring with a disk-like Au in the center. The wideband absorption mechanism benefits from the hybridized surface plasmonic modes caused by the coupling between the Au disk and the graphene ring. Besides, with the adhesion of the top Au metal disk, Fabry-Perot cavities formed by the top Au and the bottom metal produce the continuous cavity resonant modes also to enhance surface hybridization plasmons. Because the proposed broadband MA is symmetrical, it is insensitive to polarization and has a good bearing angle of 0 deg to 70 deg. The results of our study may inspire specific applications of wave modulation, including THz imaging, detecting, modulation, and sensing.

Comparison of two surface sealants on surface roughness and color stability of a commercially available denture base material – An in vitro study

Comparison of two surface sealants on surface roughness and color stability of a commercially available denture base material. Metallic discs were invested in a denture flask using dental stone to prepare a mold space. The denture base polymer and monomer were mixed in a ratio of 3:1 by volume and processed to form disc disc-shaped specimen. All the samples were finished, polished and checked for surface roughness. Sealants were applied on denture base material and cured using light-curing unit. All the 120 samples were divided into Group I(n=60) – Lucitone 199 and Optiglaze, and Group II(n=60) – Lucitone 199 and Easy Glaze. All the specimens were further subdivided into three groups based on the solution they were immersed i.e, coffee (n=20), tea (n=20), and distilled water (n=20). The specimens were checked for surface roughness and color stability for one week, one month, two months, three months, and four months. Samples were checked for surface roughness using optical profilometer and colour change using a spectrophotometer. The surface roughness of all the samples was within the normal range and tea-stained higher compared to coffee samples for color stability. The study concluded that Optiglaze is a better sealant compared to Easy Glaze with better properties like less surface roughness and good color stability of commercially available denture base materials. All groups had surface roughness less than the plaque accumulation threshold (0.20 µm). Beverages affected color stability of commercially available denture base materials after the application of two different surface sealants.

Improvement of Response Time and Heat-Transfer Capacity of Metamaterial Absorber for Terahertz Detector Applications

We have introduced a THz metamaterial absorber (MMA) system that consists of a metal disk antenna connected to successive dielectric and metal layers via a metal rod. The heat-transfer speed and capacity of the proposed platform with a metal rod inserted through the dielectric layer have been numerically studied for the first time in this work. The proposed THz MMA system can improve the heat-transfer capacity of 0.7 K/s compared to without a metal rod situation. The simulation proves that heat transfer can be achieved in the proposed absorber less than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10 ~\mu \text{s}$ </tex-math></inline-formula> times compared to without a metal rod case. The simulation results indicate that the absorption strength of the MMA is almost independent of the rod depth. This detector system will be remarkably beneficial for imaging applications where fast heat-signal conversion is necessary.

Frequency-Domain Analysis and Design of Thomson-Coil Actuators

Thomson coil actuators consist of an electric coil repelling a metallic disk. They are considered the fastest electromagnetic actuators for short displacements and for this reason are favored for DC circuit breakers. Although the basic physics are understood, the actuator's minimal components are very interdependent, making analysis difficult. Actuator design so far has thus been limited to trial and error based on finite-element models. In this paper, a novel approach is presented based on the electromagnetic frequency response of the actuator. This method is shown to be an intriguing analysis tool and various actuator design directions are presented. Experimental results provide a confirmation of the analysis.

Medial wall reconstruction using metal disc augments in revision total hip arthroplasty.

Medial acetabular bone defects are frequently encountered in revision total hip arthroplasty (THA), but few studies have focused on their reconstruction. This study aimed to report the radiographic and clinical results after medial acetabular wall reconstruction using metal disc augments in revision THA. Forty consecutive revision THA cases using metal disc augments for medial acetabular wall reconstruction were identified. Post-operative cup orientation, the centre of rotation (COR), stability of acetabular components and peri-augments osseointegration were measured. The pre-operative and post-operative Harris Hip Score (HHS) and Western Ontario and McMaster Universities Arthritis Index (WOMAC) were compared. The mean post-operative inclination and anteversion were 41.88 ± 6.70° and 16.73 ± 5.35°, respectively. The median vertical and lateral distance between the reconstructed CORs and the anatomic CORs were -3.45 mm (interquartile range [IQR]: -11.30 mm, -0.02 mm) and 3.18 mm (IQR: -0.03 mm, 6.99 mm). Thirty-eight cases completed the minimum twoyear clinical follow-up, whereas 31 had a minimum twoyear radiographic follow-up. Acetabular components were radiographically stable with bone ingrowth in 30 cases (30/31, 96.8%) while one case was classified as radiographic failure. Osseointegration around disc augments was observed in 25 of 31 cases (80.6%). The median HHS improved from 33.50 (IQR: 27.50-40.25) pre-operatively to 90.00 (IQR: 86.50-96.25) (p < 0.001), whereas the median WOMAC significantly improved from 38.02 (IQR: 29.17-46.09) to 85.94 (IQR: 79.43-93.75) (p < 0.001). In revision THA with severe medial acetabular bone defect, disc augments could provide favorable cup position and stability, peri-augments osseointegration, with satisfactory clinical scores.