Thermal and Electrical Conductivity of Copper-Graphene Heterosystem: An Effect of Strain and Thickness

Copper-graphene (Cu/Gr) composite carries high thermal (κ) and electrical (σ) conductivities compared with pristine copper film/surface. For further improvement, strain is applied (compressive and tensile) and thickness is changed (of both copper and graphene). It is observed that electronic thermal conductivity (κ_e) and σ enhance from 320.72 to 869.765 W mK⁻¹ and 5.28 × 10⁷ to 23.01 × 10⁷ S m⁻¹, respectively, by applying 0.20% compressive strain. With the increase in copper thickness (three to seven layers) in Cu(111)/single-layer-graphene (SLG) heterosystem, κ_e increases from 320.72 to 571.81 W mK⁻¹ while electrical resistivity (ρ ∝ (1/σ)) decreases from 0.189 × 10⁻⁷ to 0.117 × 10⁻⁷ Ωm. Furthermore, with the increase in graphene thickness (one to four layers) in seven-layer Cu(111)/multilayer-graphene (MLG) heterosystem, κ_e enhances upto 126% while ρ decreases upto 70% compared with the three-layer Cu(111)/SLG. A large available state near Fermi level (of Cu/Gr heterosystem) offers the conduction of more electrons from valence to conduction bands. The increasing thickness broadens this state and enhances conduction electrons. The electron localization function decreases with increasing thickness, suggesting electrons are delocalized at copper-graphene junction, resulting in an increase of free electrons that enhance κ_e and σ. Herein, it is useful in advancing the thermal management of electronic chips and in applying hybrid copper-graphene interconnects.     

Electrochemical biosensor based on gold coated iron nanoparticles/chitosan composite bound xanthine oxidase for detection of xanthine in fish meat

A xanthine oxidase was immobilized covalently onto chitosan bound gold coated iron nanoparticles (CHIT/Fe-NPs@Au) electrodeposited on the surface of pencil graphite electrode (PGE). A xanthine biosensor was fabricated using XOD/CHIT/Fe-NPs@Au/PGE as working, Ag/AgCl as reference and Pt as auxiliary electrode connected through potentiostat. The enzyme electrode was characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and electrochemical impedance spectroscopy (EIS). The biosensor exhibited optimum current response within 3 s at pH 7.4, 35 °C and working range 0.1–300 μM, when polarized at 0.5 V vs Ag/AgCl. The sensitivity of the biosensor was 0.001169 mAμ M^–1 cm^–2 with detection limit of 0.1 μM (S/N = 3). The biosensor showed only 25% loss in its initial activity after its 100 uses over 100 days, when stored at 4 °C.     

Effect of lamina orientation,crack severity,and fillers on dynamic parameters of hybrid composite cantilever beam with double transverse cracks

Modern-day research in composite material development primarily focuses on tailoring combinations by proportions of constituent materials and monitoring the changes in their targeted properties. In line with this trend, a new class of glass fiber reinforced polymer hybrid composite beam of size 600 mm×50 mm×6 mm is fabricated by adding graphene (average particle size:10 μm), and flyash (average particle size: 60 μm). The dynamic behavior of the hybrid beam by introducing two transverse cracks at different positions with varying crack depths is studied by employing analytical, finite-element, and experimental approaches. The dimensionless relative natural frequencies of the cracked/faulty hybrid beam obtained by the proposed methods are compared with the intact hybrid beam. Also, a comparison is made for the hybrid beam with a single crack. An increase in relative crack depth resulted in an increase in values of dimensionless compliances. Further, the effect of fiber orientation and lamina stacking sequence on the dynamic parameters of the hybrid beam are also analyzed. The introduction of the second crack induces higher nonlinearity in bending modes of vibration.     

The Effect of Dual Dummy Gate in the Drift Region on the on-State Performance of SOI-LDMOS Transistor for Power Amplifier Application

Silicon - The present work proposes a novel dual dummy gate Silicon-on-Insulator Laterally Double Diffused Metal-Oxide-Semiconductor (SOI-LDMOS) transistor. TCAD simulation shows considerable...     

Machinability and surface morphology investigations of multiwall carbon nanotube reinforced aluminium 7075 metal matrix composite during electrical discharge machining: A grey relational approach

Multiwall carbon nanotube buttressed aluminium 7075 metal matrix composite was synthesized through an amended liquid metallurgy method, which consisted semisolid stirring, ultrasonic treatment and squeeze casting. Aim was to investigate its machinability and surface morphology during electrical discharge machining. Variable machining factors were peak current, pulse-on time and gap voltage, whereas the responses under investigation were electrode wear rate, material removal rate and average surface roughness. Results revealed electrode wear rate, material wear rate and average surface roughness increased on increasing peak current and pulse-on time, but all these responses behaved inversely with the increase of gap voltage. Average surface roughness reduced by around 44 % on reducing the peak current from 10 A to 4 A and increasing gap voltage from 55 V to 80 V at constant pulse-on time of 300 μs; however, it increased by around 25 % on reducing the gap voltage from 80 V to 55 V and increasing the pulse-on time from 100 μs to 300 μs at constant peak current of 10 A. Significance of the process parameters were verified, regression models were developed and morphology of the machined surfaces was studied. Finally, multiple response optimization was conducted following grey relational approach.     

Engineering the Protective Oxide Chemistry for Enhanced Corrosion Protection Performance of FeCuCrNiCo-CNT Composite Coatings in 3.5 M NaCl Solution Corrosive Media

Metallurgical and Materials Transactions A - Direct electrodeposition method was used to co-electrodeposit different volume fractions of carbon nanotubes in FeCuCrNiCo high entropy alloy matrix....     

Recent trends in the total characterization of new‐generation base fluids

The quality of lubricating base oils used worldwide is changing rapidly as a result of stringent environmental regulation and the pressing need for oils to perform well under severe operating conditions. For example, although the base oil market in India now depends entirely on conventional group I base oils, group II and III base oils will soon be mandatory in lubrication formulation. These oils are generally more stable towards oxidation due to the virtual absence of heteroatom‐containing compounds and to their low aromatic content. The analytical procedures developed over the years for the characterization of new and used group I mineral base oils will not be successful for all the requirements of these new oils. Thus, a systematic study is required to test the universal validity of characterisation methodology for these new‐generation base fluids. This paper focuses on the use of various analytical techniques for base oil characterization and the methodology required for the total characterization of new‐generation base oils.