Size Of Cu Research Articles

Unraveling the regulation of Mn in Cu-ZnOx formation during methanol synthesis from syngas over Cu/ZnO/Al2O3-Mn catalysts

This study unravels the regulation of Mn promoter in catalytic activity and surface identities of Cu/ZnO/Al2O3 catalysts by reaction kinetics, TPR/TPD, N2O titration experiments and in situ spectra techniques. The methanol formation EA of Cu/ZnO/Al2O3 catalyst almost remained unchanged with the addition of Mn, confirming the methanol synthesis pathways were not affected. With an increase in the content of Mn, the sizes of Cu and ZnO decreased whereas the reduction degree of ZnO to Zn0 on the catalyst surface increased, forming more Cu-ZnOx active sites in CAZ-2%Mn. TPSR confirmed that the amount of the surface CO and H species were highest in CAZ-2%Mn. Therefore, more Cu-ZnOx active site and surface species in CAZ-2%Mn accounts for the higher methanol formation activity. A detailed understanding of the regulation of Mn in the Cu-ZnOx sites formation is expected for the precise design of the CuZnAl catalysts for methanol synthesis.

Elucidation of the effect of hybrid copper/selenium nanofiller on the optical, thermal, electrical, mechanical properties and antibacterial activity of polyvinyl alcohol/carboxymethyl cellulose blend

AbstractPolymer nanocomposite samples of a polyvinyl alcohol (PVA)/carboxymethyl cellulose (CMC) blend doped with copper nanoparticles and selenium nanoparticles (Cu NPs/Se NPs) were prepared by the casting method. X‐ray diffraction analysis (XRD) patterns showed an increase in the degree of amorphous nature of the host polymeric matrix with increasing content of Cu/Se nanoparticles. The addition of 1.60 wt.%, Cu/Se NPs narrowed the indirect optical energy gap value of the nanocomposite from 3.97 to 2.39 eV. In addition, the differential scanning calorimetry (DSC) curve of the pure blend displays the miscibility of the blend components, confirmed by the presence of a single glass transition. Transmission electron microscopy (TEM) micrographs showed that the average sizes of Cu and Se nanoparticles are about 11 and 41 nm, respectively. The maximum values of AC and DC conductivity were 6.76 × 10−6 S.cm−1 and 5.49 × 10−10 for a PVA/CMC film filled with 1.60 wt.% of Cu‐Se NPs. The mechanical properties of the PVA/CMC blend improved after adding the hybrid NPs. Moreover, the antibacterial activity of the prepared samples was increased due to the filling of Cu‐Se nanoparticles to the films. Therefore, these results indicate the multifunctionality of PVA/CMC/Cu‐Se nanocomposite samples for use in electrical energy storage, solid‐polymer electrolytes, and food packaging industry.

Determining the Particle Size of Cu and Ni in Thin Cu/Ni Films using the Williamson-Hall Method

This research focuses on analyzing the particle size of a thin Cu/Ni layer produced through electroplating by varying the input voltage. The Williamson-Hall method is used to determine the particle size of the layer, and an X-ray diffractometer is used to characterize the layer. The study finds that the particle size of Cu and Ni layers with different applied voltages has different values due to various factors. The optimum voltage for the Ni layer is found to be 7.5 volts, and its overall particle size is 4.13 × 10^(-10) nm, while the particle size of Cu is 5.00 × 10^(-9) nm. The applied voltage affects the particle size produced, and the research identifies an optimum voltage at 7.5 volts.

Probing the roles of S atom and nanoparticle size over different sizes of S-modified Cu and Pd nanoparticles in regulating catalytic performance of acetylene Semi-hydrogenation

Probing the roles of S atom and nanoparticle size over different sizes of S-modified Cu and Pd nanoparticles in regulating catalytic performance of acetylene Semi-hydrogenation

Copper/carbon nanotube catalysts prepared by ion-exchange/electroreduction for electrocatalytic nitrate reduction: Enhanced performance and mechanism insight

Carbon-supported copper is a well-known catalyst for the electrocatalytic reduction of nitrate to ammonium/ammonia (ECRNA). However, relatively low Cu utilisation and/or restricted ECRNA performance currently limit its practical applications. Here, we report a novel carbon nanotubes (CNTs)-supported Cu catalyst (IE–Cu/CNTs) for ECRNA fabricated through ion-exchange/electroreduction method. Versus traditional CNTs-supported Cu catalysts, the IE–Cu/CNTs have a small particle size of Cu. Moreover, an increased electrochemical surface area and improved electron transfer were observed for the IE–Cu/CNTs, resulting in a 2.22-fold increase in the mass activity of the ECRNA, indicating enhanced Cu utilisation and ECRNA performance. In addition, the IE–Cu/CNTs exhibited high stability for ECRNA. Electrokinetic analysis, scavenging experiments, and online electrochemical mass spectrometry measurements confirmed that ECRNA is regulated over the IE–Cu/CNTs by both direct electron transfer reduction and indirect atomic hydrogen reduction, with the former being the main regulator. This work offers new suggestions for the design of high-performance catalysts for ECRNA and deepens the understanding of the ECRNA mechanism on Cu-based catalysts.

An adaptive CU size decision algorithm based on gradient boosting machines for 3D-HEVC inter-coding

An adaptive CU size decision algorithm based on gradient boosting machines for 3D-HEVC inter-coding

Effect of Cu Alloying on Mechanical Properties of Medium-C Steel after Long-Time Tempering at 500 °C

This research studies the influence of the copper alloying of medium-carbon steel on mechanical properties after quenching and tempering at 500 °C. The microstructure was characterised using SEM, EBSD, TEM, and XRD analysis. The mechanical properties were comprehensively investigated using hardness measurements, tensile and Charpy impact tests and solid solution, grain boundary, dislocation, and precipitation strengthening contributions were estimated. Higher yield strength for Cu-alloyed steel was confirmed at about 35-73 MPa. The precipitation strengthening contribution from Cu precipitates in the range of 11-49 MPa was calculated. The interaction between Cu precipitates and dislocations retards the decrease in dislocation density. Similar values of effective grain size of martensite crystals were measured for Cu-alloyed and Cu-free steel as well. Copper alloyed steel exhibited significantly deteriorated impact toughness, total plastic elongation, and reduction of area. The size of Cu precipitates ranged from 8.3 nm after tempering at 500 °C for 6 h to 13.9 nm after tempering for 48 h.

Combining ultrafiltration and diffusive gradients in thin films techniques for speciation/fractionation of Cu and Zn in cytosol of liver of Nile tilapia (Oreochromis niloticus).

This work aims to evaluate the size and lability of Cu and Zn bound to proteins in the cytosol of fish liver of Oreochromis niloticus by employing solid-phase extraction (SPE), diffusive gradients in thin films (DGT), and ultrafiltration (UF). SPE was carried out using Chelex-100. DGT containing Chelex-100 as binding agent was employed. Analyte concentrations were determined by ICP-MS. Total Cu and Zn concentrations in cytosol (1g of fish liver in 5ml of Tris-HCl) ranged from 39.6 to 44.3ng ml-1 and 1498 to 2106ng ml-1, respectively. Data from UF (10-30kDa) suggested that Cu and Zn in cytosol were associated with ∼70% and 95%, respectively, with high-molecular-weight proteins. Cu-metallothionein was not selectively detected (although 28% of Cu was associated with low-molecular-weight proteins). However, information about the specific proteins in the cytosol will require coupling UF with organic mass spectrometry. Data from SPE showed the presence of labile Cu species of ∼17%, while the fraction of labile Zn species was >55%. However, data from DGT suggested a fraction of labile Cu species only of 7% and a labile Zn fraction of 5%. This data, as compared with previous data from literature, suggests that the DGT technique gave a more plausible estimation of the labile pool of Zn and Cu in cytosol. The combination of results from UF and DGT is capable of contributing to the knowledge about the labile and low-molecular pool of Cu and Zn.

Understanding heavy metal distribution in timberline vegetations: A case from the Gongga Mountain, eastern Tibetan Plateau

To quantify impacts of vegetation and topographic factors on heavy metal accumulation in montane forests, we assessed the spatial distribution and determined the sources of mercury (Hg), cadmium (Cd), lead (Pb), chromium (Cr), copper (Cu) and zinc (Zn) in timberline forests of Gongga Mountain. Our results show that vegetation type has little impact on the soil Hg, Cd and Pb concentrations. The soil concentrations of Cr, Cu and Zn are controlled by litter return, moss and lichen biomass, and canopy interception, with the highest concentrations in shrub forest. In contrast to other forests, the soil Hg pool in coniferous forest is significantly high due to the elevated Hg concentration and greater biomass production in litter. However, the soil pool sizes of Cd, Cr, Cu and Zn show a distinct increase along the elevation, which are attributed to the elevated heavy metal inputs from litter and moss, as well as the greater cloud water-induced atmospheric heavy metal depositions. The highest Hg concentrations of the aboveground parts of plant are in the foliage and bark, while the concentrations of Cd, Pb, Cr, Cu and Zn in the branch and bark are the highest. The decreased biomass density leads to a downward trend in the total vegetation pool sizes of Hg, Cd, Pb, Cr, Cu and Zn by 0.4–4.4 times with increasing elevation. The statistical analysis finally suggests that Hg, Cd and Pb mainly originate from anthropogenic atmospheric deposition, whereas Cr, Cu and Zn are mainly from natural sources. Our results highlight the importance of vegetation types and terrain conditions on distribution patterns of heavy metal in alpine forests.

Influence of microalloying with B on the microstructure and properties of brazed joints with Ag–Cu–Zn–Sn filler metal

Abstract Processing and formation of Ag–Cu–Zn–Sn filler metals with high Sn content are difficult owing to their high brittleness. A composite flux-cored silver (Ag) filler metal of a CuSn + XB alloy powder was designed using the principle of in situ synthesis. Copper–Copper (Cu–Cu) joints were obtained using a novel Ag-based filler metal (at B contents of 0, 2, and 3%). The microstructure and evolution of the mechanical properties of the Cu–Cu brazed joints were studied by field emission scanning electron microscopy, electron probe microscope, electron backscattering diffraction, tensile testing, and nanoindentation tester. The brazed joints mainly consisted of Ag-based solid solution (Ag(s.s)) and Cu-based solid solution (Cu(s.s)). Due to the addition of 3% B, (Ag + Cu) eutectic network structures were formed in the brazing seam. At the same time, the grain size, texture strength, misorientation distribution, and deformation of Ag(s.s) and Cu(s.s) in the brazing seam changed significantly. The overall microhardness of the brazing seam significantly increased as the B content increased in the filler metals. The tensile strength of the joints followed a parabola. At the B content of 2%, the ultimate tensile strength of the Cu–Cu joints was 248.0 MPa. The brazed joints featured intergranular, dimple, and cleavage fractures.

Properties of Composite Electrodes for All-solid-state Fluoride-ion Secondary Batteries Processed by High-pressure Torsion

All-solid-state fluoride-ion batteries (FIBs) using metal/metal fluorides are expected to be the next generation of storage batteries because they exhibit high volumetric energy densities by utilizing multielectron reactions, compared to the current lithium-ion batteries. However, method of fabricating a composite electrode for all-solid-state fluoride-ion batteries has not yet been established. A fabrication method for a composite electrode that disperses the active material and solid electrolyte is required. To approach this problem, in this study, we employed a high-pressure torsion (HPT) method, in which an active material, solid electrolyte, and conductive agent can be mixed with size reduction, as a new process and prepared Cu (active material)/PbSnF4 (solid electrolyte)/acetylene black (conductive agent) cathode composites. The crystalline sizes of Cu and PbSnF4 were significantly reduced. The apparent grain boundary resistance was also reduced owing to the more homogeneous distribution in the cathode composites after HPT processing. These structural and morphological changes led to high electrochemical performances, compared to a cathode composite without HPT.

Fast CU size decision algorithm for VVC intra coding

Fast CU size decision algorithm for VVC intra coding

Analysis of size and concentration of nanoparticles contained in cutting fluid during turning of 316L steel in minimum quantity lubrication conditions

The paper presents an important issue concerning the size and concentration of copper nanoparticles in a nanofluid. The influence of nanoparticles on the stabilization of the nanofluid, tool vibrations during turning of 316L stainless steel and the machined surface topography were described. Four sizes of Cu nanoparticles were used: 22 nm, 35 nm, 65 nm, 80 nm and four types of concentration: 0.25 %, 0.5 %, 0.75 % and 1 %. For all prepared types of nanoliquids, the ultrasonic dispersion was obtained after 50 min, and the nanoliquids with smaller nanoparticle sizes were the most stable. The lowest values of the initial parameters, both vibrations and selected parameters of 3D surface topography, were observed for the smallest size of Cu (22 nm) and a concentration of 0.5 %. The article presents how important is the problem of determination both the size and concentration of copper nanoparticles in the MQL method.

Fast CU Partitioning Algorithm for VVC Based on Multi-Stage Framework and Binary Subnets

VVC is the latest video compression technology available, and while the coding efficiency has improved significantly over the previous generation of standards, it has also led to a dramatic increase in coding complexity. As VVC uses a QTMT division structure, the more flexible division structure also allows for a significant increase in coding time. We have built a multi-stage network framework to solve the above problem by dividing the CU into different stages according to the size of the blocks. The desired features are extracted by dynamically adjusting to the size of the input CU. Secondly, we construct a binary classification subnet to perform the classification task at each stage and can determine the QT and MT division decisions. Finally, the resulting experimental results can demonstrate that our novel two-threshold decision scheme can achieve a balance between RD performance and TS. Our method succeeds in reducing the coding time by 49.08% to 52.56%, while the complexity of the negligible BD-BR increases by only 1.10% to 1.42%.

Recyclable Cu–Ag bimetallic nanocatalyst for radical scavenging, dyes removal and antimicrobial applications

An ecofriendly and cost effective green method has been used for the synthesis of recyclable, high functional nanoparticles. Bimetallic nanoparticles (BmNPs), Cu–Ag, have been synthesized using beetroot extract as reducing and capping agent. Formation of BmNPs was initially confirmed by UV–visible analysis, having distinct peaks of Ag at 429 nm and Cu at 628 nm. FTIR analysis also confirmed the association of bioactive phytochemicals with Cu–Ag nanoparticles. Crystallinity and morphology of BmNPs was determined through X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), dynamic light scattering (DLS) and energy dispersion X-ray spectroscopy (EDAX). The size of spherical shape Cu–Ag BmNPs was found to be 75.58 nm and EDAX studies confirmed the percent elemental composition of Cu and Ag in synthesized nanocatalyst. Results of different analysis provided supported evidences regarding the formation of BmNPs. Catalytic potential of BmNPs was tested for the degradation of rhodamine B (Rh–B), methylene blue (MB) and methyl orange (MO) dyes. Cu–Ag BmNPs exhibited outstanding catalytic activity for the degradation of selected organic dyes and percent degradation was recorded more than 90% for each dye. In addition, antiradical property of BmNPs was tested employing DPPH● and ABTS●+ assays and it was found to be promising. Synthesized BmNPs also exhibited strong antimicrobial activity against Salmonella typhimurium and Bacillus subtilis. Recyclability of nanoparticles was also evaluated and recovery from dye degradation reaction mixture was successfully achieved. The recovered nanoparticles exhibited same catalytic potential for the degradation of Rh–B. The objective of the current study was to synthesize BmNPs Cu–Ag employing a cost effective green method having promising catalytic, antiradical and antimicrobial potential. Further, BmNPs were reused after recovery from catalytic reactions, proving that BmNPs can be recycled having the same efficiency as that of a freshly prepared Cu–Ag BmNPs.

Identification and evolution of ultrafine precipitates in Fe-Cu alloys by first-principles modeling of positron annihilation

Understanding the formation and evolution of Cu precipitates in Fe-based alloys is crucial as they are key factors responsible for hardening and embrittlement. Dilute FeCu alloys are model materials for structural components in various application areas, including that of reactor pressure vessel steels for light water nuclear reactors. Positron annihilation spectroscopy (PAS) is a powerful tool to study the nucleation stage of both homogeneous and heterogeneous Cu precipitation, which are beyond the reach of most other experimental techniques. In this work, we present a first-principles study of positron annihilation in Fe-Cu systems. The positron annihilation characteristics (positron lifetimes, Doppler broadening spectra) are calculated for both homogeneous vacancy-free Cu clusters and heterogeneous vacancy-Cu complexes using two-component density functional theory. The theoretical results excellently agree with the available reference PAS experimental results. Our calculations show that the types of Cu precipitates can be clearly distinguished by positron annihilation, and the sizes of Cu precipitates can also be reasonably well estimated with our calculations. Moreover, we also successfully analyze the evolution of the experimental signals during isochronal annealing where the small Cu clusters change character. This work improves the understanding of the early-stage Cu precipitation in Fe matrix.

Fast Decision Algorithm of CU Size for HEVC Intra-Prediction Based on a Kernel Fuzzy SVM Classifier

High Efficiency Video Coding (HEVC) achieves a significant improvement in compression efficiency at the cost of extremely high computational complexity. Therefore, large-scale and wide deployment applications, especially mobile real-time video applications under low-latency and power-constrained conditions, are more challenging. In order to solve the above problems, a fast decision method for intra-coding unit size based on a new fuzzy support vector machine classifier is proposed in this paper. The relationship between the depth levels of coding units is accurately expressed by defining the cost evaluation criteria of texture and non-texture rate-distortion cost. The fuzzy support vector machine is improved by using the information entropy measure to solve the negative impact of data noise and the outliers problem. The proposed method includes three stages: the optimal coded depth level “0” early decision, coding unit depth early skip, and optimal coding unit early terminate. In order to further improve the rate-distortion complexity optimization performance, more feature vectors are introduced, including features such as space complexity, the relationship between coding unit depths, and rate-distortion cost. The experimental results showed that, compared with the HEVC reference test model HM16.5, the proposed algorithm can reduce the encoding time of various test video sequences by more than 53.24% on average, while the Bjontegaard Delta Bit Rate (BDBR) only increases by 0.82%. In addition, the proposed algorithm is better than the existing algorithms in terms of comprehensively reducing the computational complexity and maintaining the rate-distortion performance.

Morphological Control of Nanoporous Copper Formed from Conversion Reaction Synthesis

The pore architecture of nanoporous copper (NP-Cu) plays a vital role in its technological applications. The synthesis of NP-Cu by the conversion reaction has been reported, where an ionic Cu precursor (salt or oxide) is chemically reduced with n-butyllithium to form a Cu metal nanocomposite, from which the Li-containing product is removed to form NP-Cu. Anions in the Cu compound precursors significantly affect the size of Cu in the nanocomposite due to the effect of lithium salt on Cu diffusion. Thermal annealing of the nanocomposites reveals that the activation energy for diffusion correlates with the melting point of the lithium salt, which is used as a proxy for their tendencies of forming defects, indicating that Cu diffusion takes place through the bulk phase of the salt rather than the Cu/salt interfaces. This experimentally observed behavior is consistent with the results from density functional theory calculations. Further, doping the lithium salt with Mg2+ increases the defect concentration and facilitates enhanced Cu diffusion. The choice of anion in the Cu salt precursor thus provides an effective tool to enable control of the nanoscale size of Cu and the resultant NP porosity.

Microstructure evolution and mechanical behavior of copper through‑silicon via structure under thermal cyclic loading

The through‑silicon via (TSV) technique is widely applied in the latest highly integrated circuits packaging. However, one of the prevalent failure modes is caused by thermal cyclic loading from power fluctuations of the chip. Different thermal expansion coefficients of Cu and Si could cause a mismatch of thermal stresses under temperature cycling, which will lead to thermal fatigue failure of structure. In the current study, thermal cycling experiments are performed on Cu-TSV samples to investigate the effect of temperature cycling on microstructure evolution and mechanical behavior. The electron backscatter diffraction analysis is conducted to investigate the grain size, local texture and microstructure evolution of Cu. Based on the crystal plasticity theory, a constitutive model considering temperature and grain size effect is developed, and the parameters are calibrated. Combining crystal plasticity theory and finite element analysis, the effects of grain orientation and different grain sizes on the stress distribution and plastic work evolution of TSV structure under thermal cyclic loading are investigated.

Densification, microstructure, and properties of W-Mo-Cu alloys prepared with nano-sized Cu powders via large electric current sintering

• The sintering densification of W-Mo-Cu alloy was achieved with a short time and relatively low temperature. • The densification of W-Mo-Cu alloy was significantly improved using nano-sized Cu powders. • W-Mo-Cu alloy contained three new phases aside from W, Mo, and Cu phases. This study rapidly fabricated a novel W-Mo-Cu alloy by large current electric field sintering at a relatively low temperature, and the effects of the powder size of Cu on the densification, microstructure, and properties were comprehensively investigated. The particle size of Cu did not influence the phase type but significantly affected the densification, microstructure, and properties. XRD and TEM results showed that the alloy contained three new phases aside from W, Mo, and Cu phases, i.e., Mo-W ordered phase, Mo-Cu solid solution, and Cu 0.4 W 0.6 intermetallic compound. Copper powders with smaller sizes were beneficial to improving the distributional homogeneity of elements and the sintering densification. Therefore, the alloy prepared with 100 nm Cu powders had a denser and more homogeneous microstructure and better comprehensive properties than that prepared with 5 μm Cu powders. Overall, the W-Mo-Cu alloy prepared with 100 nm Cu powders at 980 °C proposed the best comprehensive properties, and its relative density can reach 98% approximately.