Thermal resistance of CNTs-based thermal interface material for high power solid state device packages

Vertically aligned carbon nanotubes (VACNTs) were synthesized over copper substrate. The diameter and length of the CNTs were 100 nm and 2–3 μm, respectively. Synthesis of CNTs was confirmed by Raman spectrum and verified by TEM as multi walled CNTs. SEM images showed the vertically aligned CNTs over Cu substrate. Strengthening of CNTs was performed by filling with Cu and SU-8 epoxy sealant in gap between the CNTs. The observed density was high for epoxy sealed CNTs. The bending ability of CNTs was checked and observed as low for epoxy sealed CNTs. The thermal resistance of the samples was measured by JESD51-2 standard for various loads. The observed resistance was low (0.277 cm²?K/W) for epoxy sealed CNTs at 1100 kPa. The calculated resistance of CNTs alone was 0.097 cm²?K/W for epoxy sealed at 900 kPa.     

Nonlinear dynamics and performance analysis of modified snap-through vibration energy harvester with time-varying potential function

Vibration energy harvesting has emerged as a promising method to harvest energy for small-scale applications. Enhancing the performance of a vibration energy harvester(VEH) incorporating nonlinear techniques, for example, the snap-through VEH with geometric non-linearity, has gained attention in recent years. A conventional snap-through VEH is a bi-stable system with a time-invariant potential function, which was investigated extensively in the past. In this work, a modified snap-through VEH wit...     

Two crystalline modifications of 1,1′‐thiobis(2‐naphthol)

The title compound, C₂₀H₁₄O₂S, has been obtained in two monoclinic forms, which differ in their unit‐cell dimensions, compactness of packing and conformation. Pairwise association of molecules occurs via complementary O—H...O hydrogen bonding.     

Selective CH Functionalization of Methane,Ethane, and Propane by a Perfluoroarene Iodine(III) Complex

Direct partial oxidation of methane, ethane, and propane to their respective trifluoroacetate esters is achieved by a homogeneous hypervalent iodine(III) complex in non‐superacidic (trifluoroacetic acid) solvent. The reaction is highly selective for ester formation (>99 %). In the case of ethane, greater than 0.5 M EtTFA can be achieved. Preliminary kinetic analysis and density functional calculations support a nonradical electrophilic CH activation and iodine alkyl functionalization mechanism.     

Mean amplitudes of vibration and related quantities for methyl cyanide

Mean amplitudes of vibration for CH₃CN and CD₃CN have been calculated from spectroscopic data and a normal coordinate analysis. The linear shrinkage effects and perpendicular amplitude correction coefficients are also reported.     

Structural and photoluminescence properties of excited state intramolecular proton transfer capable compounds-potential emissive and electron transport materials

Electronic factors influencing the photoluminescence properties and rates of excited state intramolecular proton transfer (ESIPT) reaction of o-hydroxy derivatives of 2,5-diphenyl-1,3,4-oxadiazole have been studied. The potential of these molecules as emissive and electron transport materials in designing improved organic light emitting diodes (OLEDs) has been studied by analyzing possible reasons for the unusually high Stokes shifts and ESIPT reaction rates. Time-dependent density functional theory (TDDFT) methods have been used to calculate the ground and excited state properties of the phototautomers that are the ESIPT reaction products. We study the relative effect of electron-withdrawing substituents on the proton-acceptor moiety and predict that the lowest ESIPT rate (1.9 x 10(11) s(-1)) is achieved with a dimethylamino substituent and that the Stokes shifts are around 11 000 cm(-1) for all three derivatives.     

Ab initio DFT study of Z–E isomerization pathways of <Emphasis Type="Italic">N</Emphasis>–benzylideneaniline

The ground state properties and absorption spectra of N-benzylideneaniline (NBA) have been studied at the density functional (DFT) and at the time-dependent density functional (TD-DFT) level of the theory. The equilibrium geometries of the E and Z isomers in the ground state and their vibrational frequencies have been computed. Furthermore, the excitation energies of the lowest excited singlet and triplet states and the potential energy curves along the torsion and the inversion isomerization coordinates were evaluated. The results are discussed in light of the available experimental data.     

A few characterization studies on some poly(methyl aryloxymethacrylates)

High polydispersity values obtained for the molecular weights, as determined by light scattering, osmometry, and GPC, of polymers prepared by different methods from the monomers recently synthesised indicate the presence of large quantities of low molecular weight species besides the high molecular weight species besides the high molecular weight species. Intrinsic viscosity data were used to evaluate Mark–Houwink constants K and “a” for this new series of monomers. DSC analyses show that the polymers have low T_g. X-ray diffraction studies made on the fibers show a high percentage of crystallinity in poly(methyl α-phenoxymethacrylate).