Gold Plating Research Articles

Assaying the Gold Plating: Comparing the Potential Income from Defined Benefit and Defined Contribution Pensions

Assaying the Gold Plating: Comparing the Potential Income from Defined Benefit and Defined Contribution Pensions

Highly Sensitive Fiber-Optic SPR Urea Sensor Based on ZIF-8/Urease

A highly-sensitive fiber-optic urea sensor was designed and experimentally demonstrated based on surface plasmon resonance (SPR) effect and metal-organic zeolite framework (ZIF-8)/urease modification. The SPR effect was excited by plating gold film on the thin core fiber in multimode-thin core-multimode fiber structure, which behaved high refractive index sensitivity. The ZIF-8/urease composite film was grown on the gold film by rapid aqueous phase synthesis method, in which the ZIF-8 could immobilize more urease and made urease and urea fully contact. Since the urease catalyzed urea hydrolysis would change the refractive index, the measurement of urea concentration was realized with high sensitivity and good selectivity. Experimental results showed that the urea measurement sensitivity of the proposed sensor could reach 6 nm/mM within the concentration range of 1-7 mM, which has great application potential in the field of human health monitoring.

Terahertz Hybrid Topological Chip for 10-Gbps Full-Duplex Communications

Terahertz photonic chips play an important role in next-generation information systems, such as high-speed inter/intrachip connections. Here we report a hybrid hollow-core terahertz topological planar waveguide where topological silicon pillars (assembled as expanded and compressed hexagonal clusters) are sandwiched between parallel gold plates. Assisted by numerical optimization of topological waveguide unit cells and supercells, we achieve a wide topological bandgap (relative bandwidth of 16.1%) in which two low-loss (below 0.1 dB/mm) topological pseudospin states exist and cover 81.8% of the bandgap. The dual unidirectional channel in a single waveguide path can be used for short-range (below 100 mm) 10-Gbps full-duplex on-chip transmissions under the forward error correction limit (bit error rate less than 10−3). Simulation results reveal that the communication performance of the proposed topological waveguide is largely group velocity dispersion dependent. This work may pave an avenue for high-speed integrated circuit design and applications in both electric and photonic fields.

Design and Implementation of Graphene-Based Tunable Microwave Filter for THz Applications.

A reconfigurable Substrate-Integrated Waveguide (SIW) filter operating in the THz region was designed in this work. Two SIW resonators were coupled through a magnetic iris to form a second-order filter with a double-layer substrate. The first substrate was silicon of permittivity 11.9; on top of it, silicon dioxide of permittivity 3.9 was placed. The ground and upper plane were composed of gold plates. Graphene material was then used for the tunability of the filter. A thin graphene sheet was sandwiched between the silicon dioxide substrate and the upper gold plate. An external DC bias voltage was then applied to change the chemical potential of graphene, which, in turn, managed to change the operational center frequency of the filter within the range of 1.289 THz to 1.297 THz, which translated to a bandwidth range of 8 GHz. The second part of this work centered on changing the aspect ratio of the graphene patch to change the center frequency. It was observed that the frequency changed within the range of 1.2908 THz to 1.2929 THz, which gave a bandwidth of 2.1 GHz change.

The Production of the Book of Mormon in Light of a Tibetan Buddhist Parallel

The Production of the Book of Mormon in Light of a Tibetan Buddhist Parallel

Light-induced vacuum micromotors based on an antimony telluride microplate

Manipulating motion of microobjects with light is indispensable in various technologies. On solid interfaces, its realizations, however, are hampered by surface friction. To resolve this difficulty, light-induced elastic waves have been recently proposed to drive microobjects against friction. Despite its expected applicability for arbitrary optical-absorptive objects, the new principle has only been tested with microsized gold plates. Herein, we validate this principle using a new material and report directional and continuous movements of a two-dimensional topological insulator (Sb2Te3) plate on an untreated microfiber surface driven by nanosecond laser pulses. The motion performance of the Sb2Te3 plate is characterized by a scanning electron microscope. We observe that the motion velocity can be controlled by tuning the average power of laser pulses. Further, by intentionally increasing the pulse repetition rate and exploiting the low thermal conductivity of Sb2Te3, we examine the thermal effects on actuation and reveal the motion instability induced by formations of microbumps on Sb2Te3 surfaces due to the Marangoni effects. Moreover, as the formed microbumps are heated to viscoelasticity states, liquid-like motion featuring asymmetry in contact angles is observed and characterized, which expands the scope of light-induced actuation of microobjects.

Analysis and study of the problems on the wires used in the MEG CDCH and the construction of the new drift chamber

In the MEG II detector, the measurement of the momentum of the charged particle is performed by a high transparency single volume, full stereo cylindrical Drift Chamber (CDCH). It is composed by 9 concentric layers, each consisting of 192 drift cells. The single drift cell is approximately squared, with a 20 μm gold plate tungsten sense wire surrounded by 40 μm/50 μm silver plated aluminum field wires in a ratio of 5:1. During the construction of the first CDCH, we observed the breaking of about hundred cathode wires: 97 of these were 40 μm aluminum wires, while 10 were 50 μm wires. Since the number of broken cathodes is less than 1% of the total, one can expect the influence on the track reconstruction efficiency to be not so dramatic. We verified by means of simulations that the loss of one cathode does not change the cell electric field appreciably. Here we present the results of the analysis of the effects of mechanical stress and chemical corrosion observed on these broken wires. Finally, we show the studies carried out on new wires to overcome the weaknesses found and the process that will be used for the construction of the new drift chamber (CDCH2). It will be built with the same modular technique, as for the previous one, the use of the wiring robot will be optimized to improve some weaker step in the procedure, new wires will be adopted with a 25% thicker diameter, which has very little effects on the resolution and efficiency of the detector. Furthermore these wires are made with a manufacturing process different from that used previously.

Accurate estimation of peak vertical ground reaction force using the duty factor in level treadmill running.

This study aimed to (1) construct a statistical model (SMM) based on the duty factor (DF) to estimate the peak vertical ground reaction force ( ) and (2) to compare the estimated to force plate gold standard (GSM). One hundred and fifteen runners ran at 9, 11, and 13 km/h. Force (1000 Hz) and kinematic (200 Hz) data were acquired with an instrumented treadmill and an optoelectronic system, respectively, to assess force-plate and kinematic based DFs. SMM linearly relates to the inverse of DF because DF was analytically associated with the inverse of the average vertical force during ground contact time and the latter was very highly correlated to . No systematic bias and a 4% root mean square error (RMSE) were reported between GSM and SMM using force-plate based DF values when considering all running speeds together. Using kinematic based DF values, SMM reported a systematic but small bias (0.05BW) and a 5% RMSE when considering all running speeds together. These findings support the use of SMM to estimate during level treadmill runs at endurance speeds if underlying DF values are accurately measured.

Rapid and Scalable Fabrication of Low Impedance, 3D Dry Electrodes for Physiological Sensing (Adv. Mater. Technol. 11/2022)

Electrophysiological Sensors In article number 2200342, Ryan Kaveh, Ana C. Arias, and co-workers present a fabrication method for rapidly producing low impedance, anatomically fit dry electrodes that do not require hydrogels. By using electroless copper and gold plating with 3D printing, biocompatible electrodes can be optimized for individuals at a fraction of the cost of existing vacuum deposition-based techniques.

Fiber-Optic Vector-Magnetic-Field Sensor Based on Gold-Clad Bent Multimode Fiber and Magnetic Fluid Materials.

A kind of bent multimode fiber (MMF) vector magnetic sensor based on surface plasmon resonance (SPR) was proposed. By plating gold film on the curved part of the bent multimode fiber, the surface plasmon mode (SPM) was excited via a whispering gallery mode (WGM). Fabricating the structure only required bending the fiber and plating it with gold, which perfectly ensured the integrity of the fiber and made it more robust compared with other structures. The sensor used magnetic fluid (MF) as the magnetically sensitive material. Through monitoring the shift of the surface plasmon resonance dip, the as-fabricated sensor not only had a high magnetic field intensity sensitivity of 9749 pm/mT but could also measure the direction of a magnetic field with a high sensitivity of 546.5 pm/°. The additional advantages of the proposed sensor lay in its easy fabrication and good integrity, which make it attractive in the field of vector-magnetic-field sensing.

Electroless Deposition of 4 μm High Ni/Au Bumps for 8 μm Pitch Interconnection

We propose that electroless plating is a superb approach to preparing metallic bumps with an ultrafine pitch for the integration of a micro light-emitting diode (micro-LED). Electroless plating does not suffer from lift-off-related issues, which are ubiquitous in thermal evaporation. Besides, it can result in much more uniform bumps than electroplating because the bump height is not affected by the current distribution. This study reports ultrafine pitch Ni/Au bumps fabricated by electroless nickel immersion gold (ENIG) plating. Furthermore, cheap metals iron and nickel are selected to catalyze the electroless nickel process. The results indicate that uniform and consistent Ni/Au bumps can be obtained through the iron sheet and nickel layer method. Besides, no voids and impurities are found inside the bumps, which is beneficial for the following interconnection process. Moreover, the change in Ni bump height values with the electroless plating time is also provided.

Pioneer Mother

Pioneer Mother

До інтерпретації образів на амулетах-підвісках IV ст. до н. е. з Пісочинського могильника

The paper provides an analysis of the iconography and semantics of two ancient Egyptian amulets-pendants made of “Egyptian faience” found in the Scythian female burial No. 1 of mound No. 8 of the Pisochynsky burial ground (Kharkiv region). The burial dates to the end of the 4th century BC. Currently, these objects are stored in the basement of the M. F. Sumtsov Kharkiv Historical Museum (inv. nos. M-2759 and M-2760). Faience amulets were suspended from earrings in the form of a ring made of gold wire. They made up a single ensemble of the headdress of the buried woman, together with a rich headdress decorated with gold plates. Amulets have different sizes and differences in style, but schematically depict the same zoomorphic creature. This is a picture of a pig. In ancient Egypt, amulets in the shape of a pig did not become widespread and are known from finds of the New Kingdom and the Late Period. In the Late Period, one of the centers of their production was the Greek settlement of Naukratis, which produced various products from “Egyptian faience” for export. They are known both in the Mediterranean and Black Sea regions. Despite considerable sketchiness, the amulets from the Pisochynsky burial ground can be reliably identified precisely as the image of a pig, which is proved by comparison with the amulet inv. no. AN1896-1908-EA.889, Oxford, Ashmolean Museum. The authors believe that the population of Forest-Steppe and Steppe Scythia did not know the authentic meaning of these and similar Egyptian amulets. They could be perceived as images of the Otherworld creatures, which, firstly, introduced them into the circle of priestly attributes, and secondly, gave them a meditative function in the funeral rite.

Narrowband metamaterial absorbers based on interlaced T-shaped all-dielectric resonators for sensing application

In this paper, a narrowband metamaterial absorber and its complementary structure absorber are proposed, which can be used for refractive index sensing in the terahertz (THz) band. The proposed two absorbers are composed of complementary rotating interlaced T-shaped all-dielectric resonators located on gold plates. It is demonstrated that the interlaced T-shaped absorber has a narrow single absorption peak with absorptivity of 99.4% at 2.987 THz; its full width at half maximum (FWHM) is 0.0219 THz, and the relative bandwidth is 0.73%. The complementary absorber has two narrow absorption peaks at 3.171 THz and 3.409 THz with absorptivity of 99.3% and 99.8%, corresponding FWHMs of 0.0133 THz and 0.0074 THz, and relative bandwidths of 0.42% and 0.22%, respectively. Based on the narrowband absorption characteristics of the absorbers, the sensing applications for different refractive indices of analyte layers are studied. The sensing sensitivity of the two absorbers can reach 1030 GHz/RIU and 3190 GHz/RIU, respectively. The proposed absorbers are promising in the fields of electromagnetic detection, imaging, and sensing.

Modified blink dynamic index predicts activity and severity in patient with facial nerve palsy.

We analyzed the dynamics of blink and defined the blink index in facial nerve palsy (FNP) patients using an ocular surface interferometer associated with clinical characteristics and clinical progress. In total, 49 patients were enrolled this study. All patients were tested using an ocular surface interferometer which is used to measure blink patterns (total blink (TB), partial blink rate (PBR)) and blink dynamics (blink time (BT), lid closing time (LCT), closure time (CT), lid opening time (LOT), interblink time (IBT), closing speed (CS), and opening speed (OS)) using 600 frames recorded over 20 s. The distance of lagophthalmos and modified interpalpebral fissure (IPF), which was defined as the actual moving distance of the upper eyelid, subtracting the distance of lagophthalmos from IPF, was measured using the ImageJ program. The types of FNP were "idiopathic" (Bell's palsy) and "surgical" (following the neurosurgery). Patients were classified into "acute" and "chronic" based on the duration of 6 months from the onset time of FNP. The clinical characteristics were classified into mild or severe according to the severe degree of exposure keratopathy-as "severe" if treatment such as tarsorrhaphy and gold plate insertion was required. Reduced MRD1, brow height, and modified IPF and increased lagophthalmos were noted in the palsy side. LCT was longer and CS, modified CS, and modified OS were shorter in the palsy side. The LCT was longer and the modified CS was shorter in idiopathic patients with acute onset and with clinically severe. IBT was increased in idiopathic patients with clinically severe. Analyzing the blink patterns and blink dynamics, this study suggests meaningful indicators among blink profiles and dynamics, LCT, and modified CS based on modified IPF. It was more associated in the idiopathic type than in the surgical type of FNP patients. The modified CS can be a useful tool for evaluating the activity and severity indicator of FNP.

Floatability and calculated reactivity of sulfide minerals and gold

The paper provides the results of theoretical reactivity calculations for gold, molybdenum, stibnite, galena, chalcopyrite, arsenopyrite and pyrite in comparison with such experimental data as the floatability of monomineral fractions with butyl xanthate, wetting angle values, changes in the kinetics of the mineral electrode potential. The following calculation series in terms of reactivity and oxidizing ability were established by calculation: Au < Sb2S3 < MoS2 < PbS < CuFeS2 < FeAsS < FeS2. During the Hallimond tube flotation, natural gold grains demonstrated the highest recovery (70 %) in the рН = 5÷7 range compared to all the studied sulfides. Molybdenite and stibnite are floated at the level of 50 % under the same conditions. As pH increases towards the alkaline region, a decrease in the floatability of all sulfides except for chalcopyrite is observed. It was established that the highest recovery is achieved when the required time of conditioning with the collector is the inverse of their reactivity. The measured wetting angle of a drop of water on an untreated surface has the highest value (78°) for a gold plate, and the lowest one (67°) for pyrite, but the latter features the greatest increase in the wetting angle (by 15°) after treatment with butyl xanthate at a concentration of 10–4 mol/l and pH = 6. For molybdenite, treatment with butyl xanthate has practically no effect on the measured wetting angle. The Sb2S3 < PbS < CuFeS2 < FeAsS < FeS2 series is determined according to the electrode potential in the рН = 2.0÷5.6 range. Theoretical calculations and experimental data obtained when studying monofractions of sulfides and gold showed that experimental conditions (pH, conditioning time, collector concentration) significantly affect the floatability. The calculated reactivity of chemical sulfide compounds and gold in comparison with experimental results proved the importance of maintaining certain flotation conditions to create contrast in the floatability of minerals.

Study of citrate gold plating by different pulse modes with and without vibration

PurposeThe purpose of this paper is to explore the optimum average current density and pulse width for electrodeposition of gold in citrate electrolyte, and it is verified that the uniformity of film thickness can be effectively improved by periodic pulse reverse electroplating.Design/methodology/approachApply forward pulse current, forward group pulse current and periodic pulse reverse current to the electrolyte and compare the film quality. High-frequency group pulses are used in both forward and reverse directions of the periodic pulse reverse current.FindingsIt is verified by experiments that periodic pulse reverse plating is superior to forward pulse plating and forward group pulse plating in terms of particle size, compactness, impurity content and thickness uniformity of the film. Add low-frequency vibration to the cathode under the same pulse electrical parameters as a comparative experiment to prove the beneficial effect of vibration on the allowable limiting current density and plating rate.Originality/valueGold film is often used as the sealing layer of precision parts. Increasing the thickness uniformity and improving the compactness of gold film will help to reduce the size error, improve the subsequent assembly accuracy and increase the service life of wear-resistant layer. Citrate gold plating electrolyte combines the advantages of cyanide electrolyte and cyanide-free electrolyte. Hence, this research focuses on the characteristics of periodic pulse reverse plating in terms of particle size, compactness, impurity content and thickness uniformity of the film and compare it with forward pulse plating and forward group pulse plating.

Binary droplet interactions in shear water-in-oil emulsion: A molecular dynamics study

The shear field and binary droplet interaction regimes of water-in-oil emulsions between parallel gold plates were investigated by molecular dynamics (MD) methods. The developed MD model was subjected to dimensional analysis and the dimensionless numbers that guarantee the similarity between the model and the actual system were identified as the capillary number (Ca), Reynolds number (Re), Weber number (We), and dimensionless time (τ). The effects of different pressures were compared by applying different forces perpendicular to the shear direction to the parallel plates. The heptane formed adsorbed layers on the gold plates, exhibited a shear thinning characteristic, and formed a no-slip uniform shear field driven by the parallel plates. The interactions between gold atoms and a heptane molecule have been investigated in depth by quantum chemical methods and it has been found that the nature of the adsorption is a van der Waals interaction. Three main binary droplet interaction regimes are produced in the presence of shear fields: coalescence, a temporary bridge formation, and sliding. The effects of capillary forces and shear effects on liquid bridges were discussed. Droplet trajectories and deformations under different pressure were analyzed. Finally, the effect of initial offset (ΔYin/2R) and Ca on the droplet interaction regime was investigated through regime maps. It was found that the coalescence regime has upper critical points for ΔYin/2R and Ca; droplet slipping occurs mainly at higher ΔYin/2R; the temporary bridge formation regime appears mainly at higher Ca. This study provides a new idea for understanding binary droplet interactions in shear emulsions.

The Cation Role in Ion Transport Selectivity of Gold-Plated Nanotubes

Ion permselectivity is an important ionic transport property exhibited in nanopores and nanotubes. Permselectivity develops due to the strong interactions between ions in solution and the nanopore/nanotube surfaces. Here, we study the ion permselectivity of gold-plated nanotube membranes. Gold-plated membranes were obtained by using an electroless gold plating method to deposit gold nanotubes into the pores and on the faces of track-etched polycarbonate membranes. These membranes have the potential to display cation permselectivity due to the excess surface charge density present on the membrane from chemisorbed Cl- anions. The cation permselectivity of membranes with 9.9 + 0.6 nm diameter nanotubes was studied potentiometrically by using a concentration cell. A new Debye-sphere based model was presented here to describe the extent of permselectivity. However, some ion specific effects with the gold-plated membrane are observed that cannot be interpreted by Debye theory. These ion-specific surface interactions lead to a reduction in the negative surface charge, causing no permselectivity for some cations as demonstrated by their lower than ideal cation transference numbers. Quantification of the surface charge density by XPS indicated the gold-plated membranes are highly charged due to Cl- chemisorption with a surface charge density of ~ 5.3 uC per cm2 corresponding to 3.3 x 1013 Cl--ions per cm2.

W‐Band High‐Efficiency Waveguide Slot Array Antenna with Low Sidelobe Levels Based on Silicon Micromachining Technology

A high-efficiency waveguide slot array antenna with low sidelobe level (SLL) is investigated for W-band applications. The silicon micromachining technology is utilized to realize multilayer antenna architecture by three key steps of selective etching, gold plating and Au-Au bonding. The radiating slot based on this technique becomes thick with a minimum thickness of 0.2 mm and accompanies with the decrease of slot's radiation ability. To overcome this weakness, a stepped radiation cavity is loaded on the slot. The characteristic of cavity-loaded slot is investigated to synthesize the low-SLL array antenna. The unequal hybrid corporate feeding network is constructed to achieve sidelobe suppression in the E-plane. A pair of 16 × 8 low-SLL and high-effciency slot arrays is fashioned and confirmed experimentally. The bandwidth with the radiation effciency higher than 80% is 92.3–96.3 GHz. The SLLs in both E- and H-planes are below −19 dB.