Modeling and design of a tuned liquid damper using triangular-bottom tank by a concentrated mass model

Nonlinear Dynamics - Rectangular flat-bottom liquid tanks known as tuned liquid dampers (TLDs) are often used as passive mechanical dampers. Sloped- and triangular-bottom TLDs have been reported to...     

Cross‐sectional structural characterization of the surface of exfoliated HOPG using HRTEM‐EELS

We analyzed the surface atomic structure of highly oriented pyrolytic graphite (HOPG) substrate exfoliated with adhesive tape, using high‐resolution transmission electron microscopy and scanning transmission electron microscopy‐electron energy‐loss spectroscopy (STEM‐EELS). The surface step height of the exfoliated HOPG substrate was determined using high‐angle annular dark‐field‐scanning transmission electron microscopy (HAADF‐STEM) images and the depth profiles of the EELS spectra of a cross‐sectioned thin foil specimen prepared via focused ion beam milling. The exfoliated surface of the HOPG substrate presented disordered and curved graphene layers. The STEM‐EELS measurements indicated that upon exfoliation, the surface of the HOPG substrate reacted with atmospheric water and oxygen molecules.     

CO2 laser drives extreme ultraviolet nano-lithography — second life of mature laser technology

It was shown both theoretically and experimentally that nanosecond order laser pulses at 10.6 micron wavelength were superior for driving the Sn plasma extreme ultraviolet (EUV) source for nano-lithography for the reasons of higher conversion efficiency, lower production of debris and higher average power levels obtainable in CO₂ media without serious problems of beam distortions and nonlinear effects occurring in competing solid-state lasers at high intensities. The renewed interest in such pulse format, wavelength, repetition rates in excess of 50 kHz and average power levels in excess of 18 kiloWatt has sparked new opportunities for a matured multi-kiloWatt CO₂ laser technology. The power demand of EUV source could be only satisfied by a Master-Oscillator-Power-Amplifier system configuration, leading to a development of a new type of hybrid pulsed CO₂ laser employing a whole spectrum of CO₂ technology, such as fast flow systems and diffusion-cooled planar waveguide lasers, and relatively recent quantum cascade lasers. In this paper we review briefly the history of relevant pulsed CO₂ laser technology and the requirements for multi-kiloWatt CO₂ laser, intended for the laser-produced plasma EUV source, and present our recent advances, such as novel solid-state seeded master oscillator and efficient multi-pass amplifiers built on planar waveguide CO₂ lasers.     

Synthesis of 3′-allylindoline spirobenzopyrans derived from 3-allyl-3H-indoles

In this study, 8 new spirobenzopyrans were synthesized. A novel, three-step, facile route for the synthesis of 3′-allylindoline spirobenzopyrans via 3-allyl-3H-indoles was developed. The newly synthesized spirobenzopyrans were evaluated for their photochromic properties. The presence of an allyl moiety at the 3′ position did not disturb the photochromic response. The steric effects of the diallyl groups at the 3′ position affected the interconversion between colored and colorless forms. Therefore, the allyl chain in 3′-allylindoline spirobenzopyrans can be utilized to attach these compounds to a molecular matrix. Consequently, this synthetic methodology could be readily applied to the creation of new photo-switchable materials.     

Adsorption structure and work function of dicarboxylic acid on Cu(1 1 0) surface

We investigated the relation between work function and the adsorption structure of dicarboxylic acids (organic molecules) such as succinic acid (HOOC-CH₂-CH₂-COOH) and an adipic acid (HOOC-(CH₂)₄-COOH) on a Cu(1 1 0) surface (electrode) as a function of the surface temperature using a Kelvin probe (KP). The work function changes of the two acids are similar. The work function increases by adsorption at room temperature due to ionization of molecules and then decreases with increasing temperature until 450 K due to the effects of change in the dipole moment of the conformational change of the molecule. From 450 to 600 K, the work function is constant because of competition between desorption and change in the dipole moment of molecules. It then reached the clean-surface value. Experiments clarified that the work function was affected by the adsorbed difference in conformation of molecules.     

Monte Carlo simulation of magnetic nanostructured thin films

Using Monte Carlo simulation, we have compared the magnetic properties between nanostructured thin films and two-dimensional crystalline solids. The dependence of nanostructured properties on the interaction between particles that constitute the nanostructured thin films is also studied. The result shows that the parameters in the interaction potential have an important effect on the properties of nanostructured thin films at the transition temperatures.     

Composition spread metal thin film fabrication technique based on ion beam sputter deposition

A composition spread metal thin film fabrication technique based on ion beam sputter deposition method was developed. The technique enables us to fabricate any desired part or a complete binary/ternary composition spread metal thin films onto a single substrate by sequentially sputtering different target materials. Composition spread metal thin films can be deposited directly on a dielectric film in patterned electrode shape for C-V and I-V measurements. The system could be especially useful in the search for new multi-component metal gate materials.