Copper Wire Research Articles

Nanocomposites based on Cu2O coated silver nanowire networks for high-performance oxygen evolution reaction.

The development of highly active, low-cost, and robust electrocatalysts for the oxygen evolution reaction (OER) is a crucial endeavor for the clean and economically viable production of hydrogen via electrochemical water splitting. Herein, cuprous oxide (Cu2O) thin films are deposited on silver nanowire (AgNW) networks by atmospheric-pressure spatial atomic layer deposition (AP-SALD). AgNW@Cu2O nanocomposites supported on conductive copper electrodes exhibited superior OER activity as compared to bare copper substrate and bare AgNWs. Moreover, a relationship between Cu2O thickness and OER activity was established. Notably, the most effective catalyst (AgNW@50nm-thick Cu2O) demonstrated very high OER activity with a low overpotential of 409 mV to deliver a current density of 10 mA cm-2 (η 10), a Tafel slope of 47 mV dec-1, a turnover frequency (TOF) of 4.2 s-1 at 350 mV, and good durability in alkaline media (1 M KOH). This highlights the potential of AgNWs as a powerful platform for the formation of highly efficient copper oxide catalysts towards OER. This work provides a foundation for the development of nanostructured Cu-based electrocatalysts for future clean energy conversion and storage systems.

Forensic Investigation of Electrical Conduct Copper Bead Microstructure as an Effort to Identify Causes of Fire

The purpose of this study was to evaluate the characteristics of the bead formed due to short circuit, overload and direct flame treatment on NYM 3x1.5 copper power cable. Handling of short circuit and overload is carried out at a current load of 800% of the current carrying capacity (144 Amperes) and direct flame treatment is carried out at a temperature of 960 degrees Celsius. The bead specimens formed from each treatment were examined and tested in the laboratory: chemical composition examination, visual inspection, macro and micro structural examination, hardness testing, and SEM-EDS examination. The difference in the characteristics of the arc bead that is formed under short circuit conditions and overload is that in short circuit conditions the damage point is localized at a certain point, namely at the short circuit contact point, while under overload conditions the point damage is localized at one or several specific locations along the wire. The macro characteristic of arc beads formed under short-circuit and overload conditions is that they contain many cavities and a clear transition boundary between the melted/ re-solidified material and the non-melted material. While the characteristics of the granules in the form of globular formed in the direct flame treatment, do not show sharp transitions between melting/ re-solidified materials. The micro structure of NYM 3x1.5 beads of electrically conducting copper wire material under the treatment conditions: short circuit, overload and direct ignition, is an alpha (α) phase dendritic structure.

Aynı anma gerilimlerine sahip farklı iletkenlerden oluşan yüksek gerilim kabloları üzerine bir araştırma

Aluminum and copper conductors are commonly used in the transport of energy. In this work, high-voltage cables occurring aluminum and copper conductors exposed to the same rated voltage values were analyzed. In order to obtain the same current carrying capacity for copper and aluminum conductors, the relationship between the cross-sections has been determined and then the most appropriate cross-sectional values for each conductor were identified. Three different cross-sectional values have been selected for each conductor type and the calculations for the cables were carried out by using the Cable Ampacity Calculations Program (CYMCAP) within the framework of the International Electrotechnical Commission (IEC) standards. The performance of the cables has been compared in terms of material losses, cable structures and the cable costs. It is seen from the simulation results that aluminum conductor cables have lower cost and higher electrical loses than the copper conductor cables.

ОБЕСПЕЧЕНИЕ КАЧЕСТВА ПРОЕКТИРОВАНИЯ РЕЗИСТИВНОГО НАГРЕВАТЕЛЬНОГО КАБЕЛЯ НА ОСНОВЕ РАЗРАБОТКИ МЕТОДИКИ МАТЕМАТИЧЕСКОГО РАСЧЕТА

The article is devoted to developing a mathematical model for calculating the electrical and design parameters of a resistive heating cable. The aim of the work is to consider the main stages of designing a heating cable and to develop a methodology for calculating its main parameters and design, which will ensure the quality and performance characteristics of the future product that meets all modern technical, technological and economic requirements. The main stages of the heating cable design process are described and recommendations are given on selecting materials, calculating the electrical and design parameters, namely: rated power, electrical resistance, diameters and mass of conductors, insulation, shield and shell. Based on the electrically conductive shield design the paper examines in detail methods for calculating the weight and size parameters of shields in the form of a copper grounding conductor with foil, as well as in the form of a screening braid made of copper wires. The proposed methodology for calculating a resistive heating cable allows considering the design process in more detail. It is at this stage that the future product quality is determined, while ensuring the required characteristics and parameters, as well as reliability and consistency of the performance throughout the product entire life cycle.

Study on wear properties of high hardness and high thermal conductivity copper alloy for crystallization roller

The crystallization roller in thin strip continuous casting combines the cooling function of the plate crystallizer with the rolling function of the roll, thereby significantly enhancing process efficiency. This also imposes higher demands on the thermal conductivity and hardness of the crystallization roller. During the utilization of the crystallization roller, as it comes into contact with the billet, the base material must exhibit exceptional wear resistance. The thermal conductivity and mechanical properties of high-strength beryllium copper alloy C17200 and traditional crystallization material CrZrCu alloy C18150 were assessed at various temperatures using a laser thermal conductivity meter (LFA-427) and microhardness meter (ZD-HVZHT-10), respectively. Detailed analysis confirms the potential suitability of C17200 as an alternative material for crystallization rollers. The hardness of C17200 was twice that of C18150 while maintaining the original thermal conductivity. The wear characteristics of C17200 were investigated at room temperature (25 °C) and simulated operating conditions (300 °C) using a reciprocating wear tester (MZF-1). Additionally, the wear mechanism of C17200 at different temperatures was studied using scanning electron microscopy (SEM). The findings demonstrated that C17200 exhibited favorable wear resistance even at a temperature of 300 °C, thereby satisfying the performance criteria for the crystallization roller during operational usage.

Microstructure evolution of melt-extracted copper alloy wires

Copper alloy wires are regarded as essential for bonding in semiconductor packaging. However, the existing single-crystal copper wires are susceptible to oxidize, resulting in connection failure. And the current production process of multi-pass cold-drawing is complicated. In this study, nickel-aluminum-bronze (NAB) alloy wires by the melt-extracted method were investigated to avoid the problems mentioned above. The results showed that the microstructure of the copper alloy wire differs depending on the region. The nano-Ni3Al phase precipitates on the lath martensitic β' phase in the concave area, while the interior of the copper alloy wires contains a large number of reflection-twin of the β' phase. As the melt-extracted process continues, the cooling speed increases until the formation of the stable lamellar αw + β' structure. These results will shed new light on the formation mechanism of copper alloy bonding wires.

Effect of drawing speed on the deformation characteristics, microstructure and properties of copper wire rod

Currently, copper-based wire has been extensively applied in the information industry and for signal transmission due to its excellent performance in practice. Drawing speed, as a key parameter of the drawing process, has a significant impact on the production and quality of the wire. In this study, both simulation and experiment are performed to explore the evolution of deformation and damage behavior of copper wire and its microstructural properties during the process of multi-pass continuous drawing, with the drawing speed set to the range from 60 to 300 m/min. This provides guidance on the production and process optimization of the wire. It is revealed in the study that the surface of the pure copper wire is deformed more significantly than the core region, and that there is a rise in the equivalent strain and damage occurring at different locations in the longitudinal section of the wire as the number of passes increases. With the drawing speed increasing, the strain and damage occurring in the core region are reduced, while the damage caused by severe deformation on the surface shows nonlinearity. When the drawing speed increases, there is a significant improvement in the strength of the dominant texture component <101> in the copper wire, and the grain size of the wire is significantly refined. In the meantime, there is an increase in the density of dislocation within the wire. The severity of distortion caused to the grain tends to decrease, and the grain boundary is gradually blurred. By increasing the drawing speed, the surface quality of the wire is improved. Apart from that, there is a slight increase in the tensile strength, DC resistance and electrical resistivity of the copper wire, despite a decline in the conductivity of the wire.

A Flexible Sensor for Vancomycin Fabricated By Depositing Molecularly Imprinted Carbon Paste on a Wire

1. Introduction Vancomycin (VCM), an antibacterial drug, has a narrow effective blood concentration range, requiring therapeutic drug monitoring (TDM) to measure blood levels and optimize dosing regimens . Neonates, in particular, have large individual differences in the rate of drug metabolism, so strict TDM is necessary, but the dilemma is that the amount of blood drawn must be kept to a minimum. Therefore, we decided to develop a method of TDM without blood sampling by implanting a sensor that detects VCM under the skin. The sensor must be flexible enough not to damage the subcutaneous tissue. We have developed a sensor using a MIP carbon paste (MIP-CP) electrode, in which graphite particles with molecularly imprinted polymers are mixed with oil. Since higher mechanical strength is required for indwelling sensors, we fabricated MIP-carbon dough (MIP-CD) electrodes by mixing MIP with a thermosetting silicon resin prepolymer and thermosetting it. This was applied to a wire to develop a flexible wire-type sensor, and its performance was evaluated. 2. 2. experimental method 2-1. MIP graft polymerization /MIP-CD fabricationMethacrylic acid, ethylene glycol dimethacrylate, and allylamine carboxypropionic-3-ferrocene were graft copolymerized on the surface of graphite particles with fixed polymerization initiator in the presence of template VCM. Then, after washing and drying with sodium chloride solution and distilled water, the uncured MIP-CD was mixed with thermosetting silicone resin at a weight ratio of 7:3. Non-imprinted polymer (NIP)-CD, which was prepared by the same procedure without adding a template during synthesis, was also prepared for comparison.2-2. Fabrication of MIP-CD sensor Carbon ink was applied to a 20 mm tip of a 50 mm tin-plated copper wire, and uncured MIP-CD was applied on top. Then, silicon resin was applied for insulation to limit the effective area of the MIP-CD electrode, and both the insulation and MIP-CD were heat-cured in a dryer to fabricate the wire electrode shown in Fig. 1.2-3. measurement methodDifferential pulse voltammetry was performed on the MIP (or NIP)-CD sensor in phosphate buffer containing VCM or teicoplanin (TEIC), which has a similar structure, and the relationship between current and concentration was plotted. 3. Results and Discussion A comparison of the sensitivity of MIP-CD and NIP-CD electrodes to VCM is shown in Fig. 2: the current at MIP-CD increased linearly with increasing VCM concentration, while that at NIP-CD was insensitive. This result indicates that the current at the MIP-CD electrode reflects the specific binding of VCM to the imprinted binding site. As shown in Fig. 3, the MIP-CD electrode was not sensitive to TEIC and showed high selectivity. Conclusion The electrode with MIP-CD fixed on a wire is strong and flexible, yet has a specific response to VCM, and is expected to be used as an indwelling subcutaneous sensor.*This work was supported by the Bridging Research Program of the Japan Agency for Medical Research and Development (Keio University Center). Figure 1

(Invited) Gravitational Level Effects on Electrochemical Interfacial Phenomena

Electrochemical copper refining technology invented in Niagara area made a great progress over more than 100 years through better understanding of natural convection phenomena. Ionic mass-transfer rate enhanced by natural convection developing along 1m high vertical electrode surfaces has been unconsciously utilized by trial-and-error method. As the local electrolyte composition is partly stratified in an electrolytic cell (roughly 5m long x 1.3m wide x 1.3m depth). The industrial electrolytic tank house is composed of about 1000 cells through which the electrolyte is continuously supplied. Thus, the electrolyte circulation is a key technology in industrial copper refining processes as well as appropriate selection of effective additive and stable sedimentation of anode slime containing precious metals on the electrolytic tank bottom.On the other hand, Cu nanowire arrays were electrodeposited potentiostatically with PC filter template in two kinds of electrolytic cell configurations: cathode over anode (C/A) and anode over cathode (A/C). The effect of gravitational level on the coupling phenomena between the morphological variation and the ionic mass transfer rate in nanosized pores(a mesoscopic scale of a fewμm high and 30nm in diameter) was also found. Hitherto, the coupling phenomena accompanied with the electrochemical interfacial reactions confined in such a mesoscopic space has not been studies in spite of the great technological interest for the production of micro- or meso-scale fabrication techniques encountered in microelectronics and energy conversion & storage technology field. The initial stage including nucleation and growth process during electrochemical phase transformation reactions must be at first focused to profoundly comprehend the present subject in order to reasonably design such an advanced device technology.Fundamental aspects in electrochemical processes in microgravity environments have not been frequently reported. However, Artemis projects may provide the large opportunities on the energy storage and power generation, as well as materials processing. The effects of gravitational level and magnetic field gradient on the electrochemical interfacial phenomena should be understood. The drop tower facility surely offers the appropriate & “unique” experimental opportunities to propose such research program in the future space engineering fields. Electrocrystallization of metals is selected as a good subject for starting direction of research. Its reaction mechanism is relatively simple, the deposition rate can be easily varied by changing the current density or potential, and a smooth copper film is deposited so long as it is not too thick.By the way, the damascene process has been introduced to copper wiring process in ULSI field by IBM almost 25 years ago. It is important to control the nucleation and crystal growth in the initial stages of electrodeposition process. For this purpose, many effects of additive have been intensively examined. However, few quantitative examinations have been reported on the coupling phenomena of ionic mass transfer and nucleation and crystal growth. In the present work, we introduce various gravitational levels as new parameters into the nonequilibrium electrochemical processing in order to create or tailor the unique physical properties in nano space field. It is fruitful in terms of physicochemical hydrodynamics that the experiments are done under various gravitational levels. In fact, it has been confirmed that the gravitational levels as well as the magnetic field introduce the intensified effects from that under 1 G normal environment. Here is a report to analyze the effect of gravitational level on the initial stages of Cu electrodeposition on TaN or TiN substrate.

Dynamic Electrochemical Impedance Spectroscopy for Characterization of the State of Health of Graphite Electrodes

Graphitic carbon is the most used material as anode in lithium-ion batteries since the last 30 years. To make batteries cost-effective for mobility or stationary applications the optimization of every aspect is crucial. Advanced techniques can be implied to undercover or demonstrate the main chemical processes at the graphite electrode such as the Electrochemical Impedance Spectroscopy (EIS). EIS is a powerful technique able to reveal and separate resistive and capacitive properties of an interface in a non-destructive way. It has been applied for the characterization of graphite in order to quantify the charge transfer resistance on the intercalation process, to study the mechanism of formation of solid-electrolyte-interface (SEI), and reveal the lithium plating process [1]. There are high requirements for the collection of impedance spectra on a broad range of frequencies (typically from kHz to tens of mHz) at different electrode potentials regarding measurement time and the condition of a system in equilibrium. To overcome these requirements a technique has been developed called Dynamic Electrochemical Impedance Spectroscopy (DEIS). For DEIS a multi-frequency signal, containing all frequencies to probe in a form of summed sine waves, is superimposed to the galvanostatic current. Using this method, it is possible to measure the time-varying impedance while the system is drifting through non-equilibrium states, e.g. during charge/discharge cycling.In this study we propose DEIS measurements performed on a freshly assembled graphite/lithium half-cell cycled at current rates of C/10 and C/5 and 1C (for aging). Figure 1 A shows the working electrode voltage profile of the first 16 cycles. The chosen geometry for the cell is a three-electrode pouch cell with 2x2cm square electrodes and an insulated copper wire with lithium plated at the tip as micro-reference electrode (see Figure 1 B).The novelty of the proposed method is the fully automatized procedure to acquire the dynamic impedance on a wide frequency band (1kHz-10mHz) continuously over an arbitrary number of cycles to investigate the degradation of the electrode. The experimental set-up is shown as a scheme in Figure 1 C [2]. On base of the recorded current and voltage signals, we computed the time-varying impedance using the Dynamic Multi-Frequencies Analysis (DMFA). This method allows to calculate the impedance at the low frequency band by filtering of the sine components in the Fourier domain; the voltage drift is calculate in the same way [3]. An example of the computed time-varying impedance and the respective potential profile for the first cycle is reported in Figure 1 D.

N-Heterocyclic Carbene Based Nanolayer for Copper Film Oxidation Mitigation

The wide use of copper is limited by its rapid oxidation. Main oxidation mitigation approaches involve alloying or surface passivation technologies. However, surface alloying often modifies the physical properties of copper, while surface passivation is characterized by limited thermal and chemical stability. Herein, we demonstrate an electrochemical approach for surface-anchoring of an N-heterocyclic carbene (NHC) nanolayer on a copper electrode by electro-deposition of alkyne-functionalized imidazolium cations. Water reduction reaction generated a high concentration of hydroxide ions that induced deprotonation of imidazolium cations and self-assembly of NHCs on the copper electrode. In addition, alkyne group deprotonation enabled on-surface polymerization by coupling surface-anchored and solvated NHCs, which resulted in a 2 nm thick NHC-nanolayer. Copper film coated with a NHC-nanolayer demonstrated high oxidation resistance at elevated temperatures and under alkaline conditions.The ease of preparation and well-controlled growth process of electrochemically-induced NHC nanolayer make it an easily-applicable method for large-scale coating to provide thin and effective passivation layer for copper surfaces. Moreover, the electro-induced mechanism of NHC-nanolayer formation makes it possible to selectively deposit the protective layer on conducting copper wires without changing the optical properties of the entire device. These advantages make the presented technology highly suitable for applications that require high transparency, such as solar cells and electroluminescence devices.

Control of Crystallographic Growth Orientation and Twinning Structure in Copper Nanowires by Template-Assisted Electrodeposition

Synthesis and characterization of noble metal nanowires have been a popular topic in the field of microelectronic devices and catalysts. Nanotwinned copper nanowires (nt-CuNWs) possess high mechanical strength, excellent electromigration resistance and low electrical resistivity, which have been considered as a promising interconnect material in ultra-large scale integrated circuits (ICs). Here, we deposited nt-CuNWs in two different anodic aluminum oxide (AAO) templates with respective pore sizes of 70 nm and 35 nm pore by pulse electrodeposition. The influence of thermal treatment on the Cu seed layer deposited on AAO membranes prior to electrodeposition is investigated. Both coarse and thin nt-CuNWs mainly grew in <111> crystallographic direction with (111) texture coefficients (TC(111)) > 2.5, and an aspect ratio (AR) > 100 according to x-ray diffraction analysis. An addition of gelatin (14 ppm) in the copper sulfate electrolyte is found to suppress the growth of (220)-oriented Cu grains in the AAO by forming copper nanowires with large TC(111) > 2.65 and high-density nanotwin structure. This study provides a simple route to tailoring microstructure and physical properties of nanoscale copper wires, which is beneficial for the interconnect technology development in semiconductor IC devices.

Recycling of enamelled copper wire from end-of-life electric motor via room temperature methanolysis

Polyester enamelled copper wire plays an important role in the manufacturing of electric motors. In line with the electrification of transport, the demand for electric motors and the future waste generated from their end-of-life cannot be ignored. The waste from the polyester enamelled copper wire is expected to increase steadily. Methods proposed by researchers are mainly focused on thermal treatment to either pyrolyse or burn off the polyester enamel. However, thermal treatments fail to consider the potential risk of air pollution and to recover the polyester enamel.In this manuscript, we propose two-stage processes comprised of methanol washing and room temperature methanolysis with dichloromethane as co-solvent and K2CO3 as catalyst to delaminate multilayered type enamelled copper wire. The methanol washing recovers polyvinyl butyral as it is, via dissolution. Whereas the methanolysis products are dimethyl terephthalate (DMT) and dimethyl isophthalate (DMI) which are precursors to the polyester and could be used to make new polyester. At room temperature, the parameters of solid to liquid, DCM to methanol, and K2CO3 to Cuwire ratio, of 500 g/L, 1.00 mol/mol, and 0.10 wt%, respectively, allow complete removal of polyester enamel in 24 h. The methanolysis parameters described manage to give a modest DMT and DMI yield of 86.0% and 92.2%, respectively. The reaction time can be sped up by increasing the temperature by 10 °C, leading to complete depolymerisation in 4 h. Compared to thermal treatment, the proposed method requires 80.7% lower energy with the products contained within the solution.

Effects of Copper(II) Oxide on the Co-Pyrolysis of Waste Polyester Enameled Wires and Poly(vinyl chloride).

The emission of chlorinated pollutants is one of the main problems when recovering copper (Cu) via pyrolysis from waste enameled wires. This is mainly attributed to other wastes which possess high poly(vinyl chloride) content, such as electrical wires and cables, which are often recycled together with enameled copper wires. In this research, to control the chlorinated pollutants, copper(II) oxide (CuO) was chosen and demonstrated to be an efficient dechlorinating agent, and CuO did not introduce any impurities that influence the quality of the recovered Cu. The pyrolysis and co-pyrolysis of polyester enameled wires, PVC, and CuO were investigated, and special attention was paid to chlorinated compounds in released pyrolytic products. In particular, the co-pyrolysis of this ternary mixture was studied for the first time, and some new pyrolysis behaviors were discovered. For example, the results of Py-GC/MS analyses showed that the addition of CuO removed about 75% of the chloro-organic products, the main types of which were chloroaromatic compounds rather than the more toxic chloroesters. Moreover, pyrolysis gases were collected and characterized via ion chromatography, and the results showed that the chlorine content in the pyrolysis gases decreased by about 71%. TG analysis indicated that CuO only minimally affected the pyrolysis of polyester paint. However, through the chlorine fixation effect, CuO influenced the dechlorination and dehydrochlorination of PVC, as well as secondary reactions between HCl and pyrolysis products of polyester paint, therefore changing the products and behaviors of co-pyrolysis. Mechanism of reducing chlorine-containing pollutants and reaction mechanism of forming typical pyrolysis products closely correlated to the effects of CuO were also proposed, providing theoretical guidance for the recycling of waste enameled wires.

Secondary electron yield (SEY) evolution of laser processed oxygen-free high conductivity copper induced by different ultrasonic cleaning durations

Laser treated material surface has highly regular curves and greatly reduces the secondary electron yield of surface. As one of the most typically used materials in the vacuum system of particle accelerators, the surface of oxygen-free high conductivity copper (OFHC) is processed by laser. Moreover, ultrasonic cleaning can effectively remove powders and impurities produced by laser ablation. The secondary electron yield (SEY), surface morphology and surface composition of laser treated oxygen-free copper samples before and after ultrasonic cleaning were compared. Experiments were conducted by using the secondary electron yield test device, X-ray diffractometer, X-ray photoelectron spectroscopy, and scanning electron microscope to characterize the SEY, crystal structures, surface composition and surface morphology of laser-treated oxygen-free copper samples, respectively. The SEY evolution of the samples was investigated and analyzed at electron doses of 7.6 × 10−6 C mm−2: after 15-min ultrasonic cleaning, the δmax of sample #1, #2 and #3 increased from 1.09, 1.23, and 1.38 to 1.19, 1.2, and 1.63, respectively, with the maximum increase of 18.12 %. Ultrasonic cleaning could greatly reduce the accumulation of spherical particles and the fibrous or flocculent structures produced by laser processing, thereby reducing the capture of secondary electrons.

Development of a microelectrode for simultaneous &lt;i&gt;in vivo&lt;/i&gt; calcium and electrophysiological recording of hippocampal neuronal activity

Calcium (Ca2+) imaging is a commonly utilized neuroscience technique for in vivo recording of neuronal activity. It involves the optical measurement of calcium concentration using genetically encoded calcium indicators (GECI) [1]. However, the kinetics of changes in the fluorescence of GECI are relatively slow and limited by the biophysics of the calcium binding [2]. In response to single action potentials (APs) in pyramidal neurons, most of the widely used GECI have a fluorescence half-life of approximately 100 ms [3]. As a result, GECI cannot provide complete information about the dynamics of neural ensembles. To address this issue, new variants of GECI, such as jGCaMP7 [3], and jGCaMP8 [4], have been developed, or genetically encoded voltage indicators (GEVI), such as JEDI-2P [5], have been utilized. However, the speed of GECI or GEVI is still lower than that of electrophysiological registration methods. Thus, we have designed a microelectrode that can be utilized with a gradient lens for in vivo calcium imaging with a miniscope. The miniscope is a miniature microscope for single photon epifluorescence Ca2+ imaging, which enables recording of neuronal activity in freely moving laboratory animals, unlike the traditionally used two-photon imaging technique. The miniscope utilizes gradient-index (GRIN) lenses that are implanted directly into the brain of a laboratory animal, instead of a conventional lens. The gradient lens is a transparent cylinder with a diameter of 1.8 mm and a length of 3.8 mm. To facilitate electrophysiological recording, we developed a microelectrode that can be aligned with a GRIN lens. The microelectrode is a three-layer structure consisting of: 1) a polyimide film, 2) conductive copper tracks deposited through thermoforming, and 3) a polyimide film with cutouts for pads. On one side of the microelectrode, there are 12 gold-plated conductive contacts for registering local field potentials, while on the other side, a similar number of conductive tracks are present for connecting to a connector that transmits data to the processing board. The flexible microelectrode is wrapped around a gradient lens and fixed using thermoforming, after which it is implanted in the animal's brain. Using the developed microelectrode, our aim is to perform a comparative analysis of the calcium and electrophysiological activity of hippocampal neurons in freely moving wild-type mice and in a mouse model of Alzheimer's disease. This study will enable the identification of any abnormalities in Alzheimer's disease at the level of neural ensembles and may suggest new treatment approaches or mechanisms for the development of the progressive memory loss pathology associated with this disease. We would like to express our gratitude to Anastasia Viktorovna Bolshakova for her administrative assistance, and to the staff of the Laboratory of Molecular Neurodegeneration for their invaluable help and advices.

THE DESIGN OF THE POWER SUPPLY CURRENT LEADS TO A HIGH-TEMPERATURE SUPERCONDUCTING ELECTROMAGNET

The paper presents a theoretical and experimental analysis of thermal conditions imposed on the power supply conductor for an HTS YBCO-type high magnetic field electromagnet. For thermal stability during the operation of the electromagnet, it is essential to lower the heat flux from outside the system. The heat from the surrounding environment to the HTS winding is limited by using an adequately sized cryogenic system and the proper design of the current leads. The HTS winding and current leads are cooled with a two-stage GM cryocooler. If the power supply conductor's conductive heat flux exceeds the cryocooler’s heat load, the temperature of the HTS winding will increase, and system instability may occur. The power supply conductors are of two types: copper conductors and mixed HTS conductors. This work analyzes HTS conductors and junctions of HTS tape with copper terminals and their contribution to the cryocooler’s total heat load. Using HTS conductors reduces Joule heat when current passes through them (approx. 300 A) and the conductive heat flux to the HTS windings. Resistance for various soldering alloys was experimentally evaluated to evaluate the Joule heat of the junctions between HTS conductors and copper terminals.

A computational investigation of electron transport in defected Cu thin films

Interconnects are a key component of integrated circuits (IC) and play a major role in the speed and power consumption of an IC. While surface roughness is essential for ensuring adhesion to other components in an IC, it also increases electron scattering at the surface, which can dramatically increase resistivity. Barrier layers have been introduced to mitigate the effect of rough Cu surfaces, but explanations of their behavior are varied. Using a combination of density functional theory (DFT) and the non-equilibrium Green’s function technique in conjunction with DFT (NEGF-DFT), our work aims to identify key tradeoffs between surface roughness profiles and electronic performance in copper wire interconnects, and how barrier layer atoms affect conductance across the Cu surface. We find that by removing atoms from the surface, the current allowed across the film is reduced to that of a thinner pristine film, but that as the voltage is increased the defected film recovers some of the conductance of the pristine system. By replacing the vacancy with a substituent atom (Ag, Al, Au, Co, Ir, Ni, Pd, Rh, Sn, Zn, Zr) we find that conductance across the film is intimately related to the periodic table group of the substituent atom relative to Cu.

3‐D woven rectangular hollow structure conformal bearing microstrip antenna with different heights: Design, preparation, performance, and simulation

AbstractTraditional microstrip antennas have problems with heavy weight and poor gain. In order to reduce the weight of the antenna itself and improve its gain, the preforms of the 3‐D woven rectangular hollow structure conformal bearing microstrip antenna (3DWRHS‐CB‐MA)with different heights were woven from ultra‐high molecular weight polyethylene (UHMWPE) filament yarns and copper wires on a common loom through reasonable design. The preform was used as the reinforcement and epoxy resin was used as the matrix, four different heights (2, 4, 6, and 8 mm) of 3DWRHS‐CB‐MA were prepared by vacuum‐assisted resin transfer molding (VARTM) process. Finally, the electromagnetic performance was analyzed by high‐frequency structure simulator (HFSS) and experimental testing. The results showed that the frequency deviation of the 2 mm height microstrip antenna was minimal; while the 4 mm height microstrip antenna had better gain efficiency and directional diagram compared to others. The 4 mm height microstrip antenna has good radiation performance with a weight of only 35 g which shows that 3DWRHS‐CB‐MA are potential candidates for future intelligent textile materials and wireless communication fields.Highlights Weaving with UHMWPE filament yarns and copper wires on common looms. The preform was used as the reinforcement, and epoxy resin was used as the matrix. Simulation of electromagnetic characteristics of antennas using HFSS software. Proving the effectiveness of the electromagnetic simulation model. Revealing the electromagnetic radiation mechanisms.

Unprecedented electrical performance of friction-extruded copper-graphene composites

Copper-graphene composites show remarkable electrical performance surpassing traditional copper conductors albeit at a micron scale; there are several challenges in demonstrating similar performance at the bulk scale. In this study, we used shear assisted processing and extrusion (ShAPE) to synthesize macro-scale copper-graphene composites with a simultaneously lower temperature coefficient of resistance (TCR) and improved electrical conductivity over copper-only samples. We showed that the addition of 18 ppm of graphene decreased the TCR of C11000 alloy by nearly 11 %. A suite of characterization tools involving scanning and transmission electron microscopy along with atom probe tomography were used to characterize the grain size, crystallographic orientation, structure, and composition of copper grains and graphene additives in the feedstock and processed samples. We posit that the shear extrusion process may have transformed some of the feedstock graphene additives into higher defect-density agglomerates while retaining the structure of others as mono-to-tri-layer flakes with lower defect density. The combination of these additives with heterogeneous structures may have been responsible for the simultaneous decrease in TCR and enhanced electrical conductivity of the copper-graphene ShAPE composites.