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In this study, gold-loaded titanium dioxide was prepared by an impregnation method to investigate the effect of surface plasmon resonance (SPR) on photoactivity. The deposited gold nanoparticles (NPs) absorb visible light because of SPR. The effects of both the gold content and the TiO2 size of Au/TiO2 on SPR and the photocatalytic efficiency were investigated. The morphology, crystal structure, light absorption, emission from the recombination of a photoexcited electron and hole, and the degree of aggregation were investigated using transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-visible-diffuse reflectance spectra (UV-VIS-DRS), photoluminescence (PL) spectroscopy, and turbidimetry, respectively. Photocatalytic activity was evaluated by the decolorization of methyl orange solution over modified titania under UV and UV/GLED (green light emitting diode) illumination. Au/TiO2 NPs exhibited an absorption peak (530-570 nm) because of SPR. The results of our photocatalytic experiments indicated that the UV-inducedly photocatalytic reaction rate was improved by simultaneously using UV and green light illumination; this corresponds to the adsorption region of SPR. Au/TiO2 could use the enhanced electric field amplitude on the surface of the Au particle in the spectral vicinity of its plasmon resonance and thus improve the photoactivity. Experimental results show that the synergistic effect between UV and green light for the improvement of photoactivity increases with increasing the SPR absorption, which in turn is affected by the Au content and TiO2 size.

We have developed a simple approach for generating peptide-conjugated gold nanoparticles (AuNPs) from the Rev peptide and gold aqueous solution. The peptide functions as both a reducing agent and a capping molecule. AuNPs of various sizes (20-300 nm) and shapes (spheres, triangular plates, and polygons) can be obtained upon modulating the ratio of gold ions to the Rev peptide. Transmission electron microscopy, X-ray diffraction, and UV-vis spectroscopy were utilized to characterize these nanoparticles. Fourier-transform infrared and X-ray photoelectron spectroscopy measurements were performed to investigate chemical interactions between the Rev peptide and AuNPs. Lactate dehydrogenase and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays revealed that the Rev peptide-AuNP nanocomposites exhibited exceptionally high cytotoxic effects toward mouse ovarian surface epithelial cell lines, relative to the effects of equal doses of the free Rev peptide. Our study suggests a new way of utilizing biomolecule-conjugated AuNPs as potentially effective anticancer drugs.

Nowadays, thinner and slimmer smartphones have been widely applied in daily life. In most portable devices, liquid-crystal display driver integrated circuit (IC) or new touch display driver IC are critical components, in which the gold bumping process is used as an essential interconnection technology and usually outsources to out-sourced assembly and testing factories. In semiconductor packaging manufacturing, due to popular high-definition requirements of display devices, gold bumping processes require very low fraction of nonconformities. For this reason, accurately evaluating the manufacturing yield is very important to guarantee the quality requirements being met. To evaluate the yield of gold bumping processes, the most popular yield index $C_{\textrm {pk}} $ is widely employed in outsourcing contract arrangements. However, the typical existing nature estimator is a biased estimator and more conservative. In this paper, we provide an unbiased estimator to evaluate the gold bumping manufacturing yield more accurately. Based on the new estimator, we further propose a weighted parametric bootstrap method to obtain a reliable lower confidence bound that is closer to the true manufacturing yield. The new yield assessment can avoid underestimating the gold bumping manufacturing yield and can make more reliable decisions. [ABSTRACT FROM AUTHOR]

Portable devices have been popularly used nowadays. Liquid crystal display driver integrated circuit is an essential component in portable devices in which gold bumping process is a critical interconnection technology. To enhance bargaining power and to reduce cost, group suppliers are commonly selected from multiple suppliers. For high-definition display devices, a very low fraction of defectives is the basic quality requirement in gold bumping processes. Unfortunately, conventional yield measurement methods for supplier selection no longer work since any sample of reasonable size probably contains no defective gold bump product items. In this paper, we propose a group supplier selection procedure for multiple suppliers with multiple-line processes that are quite common due to high demands in semiconductor industry. For various significance levels, the number of suppliers, the number of manufacturing lines, predetermined capability requirements, and sample sizes, different selected suppliers are suggested based on the multiple-line yield index Cpk^{M} . In addition, the power comparisons between different methods are also discussed. For the illustration purpose, real-world applications in a gold bumping factory that is located in the Science-Based Industrial Park in Hsinchu, Taiwan, are included. [ABSTRACT FROM PUBLISHER]

Development of touch display driver IC (TDDI) has enabled slimmer smartphone design by virtue of the integration of touch controller and display driver ICs (DDIs) into a single chip. TDDI plays an important role in touch integrated display panels. Compared to conventional DDI, TDDI requires more bonding pads for touch applications, thus increasing the usage of gold. The requirement to keep costs down forces manufacturers to look for ways to reduce the usage of gold. In order to reduce the usage of gold, gold bumping processes with asymmetric tolerances are considered, in which deviations from the target are less tolerable in lower specification limits than in upper specification limits. In addition, due to economies of scale considerations, gold bumping processes involving multiple manufacturing lines are commonly considered in Taiwan. However, no yield index has been developed for multiple-line gold bumping processes with asymmetric tolerances. In this paper, we propose a new yield index C^\prime \prime M{pk} and derive an approximate distribution of $\hat {{C}}^{{\prime \prime M}}_{ {pk}} $ . In addition, the lower confidence bounds and critical values are provided for the multiple-line gold bumping processes with asymmetric tolerances. For illustration purposes, a real-world application in a gold bumping factory which is located in the Science-Based Industrial Park in Hsinchu, Taiwan, is presented. [ABSTRACT FROM AUTHOR]

We have previously reported the fabrication of a nanocomposite from dodecanethiol-capped Au nanoparticles (average diameter 2.6 nm) and a silica aerogel. It was found that the Au particles were efficiently adsorbed on a silica wet-gel in organic solvents. In this paper, surface analysis of the silica surface and evaluation of adsorption rates for various solvents, performed to elucidate the nature of the interaction between the capped nanoparticles and the silica gel, are described. These observations indicate that dipole-induced dipole interaction between OH groups on the silica surface and metal cores of the nanoparticles is probably important for the adsorption. It was demonstrated that, by changing the solvent polarity, spatial distribution of the nanoparticles inside the gel can be controlled. [ABSTRACT FROM AUTHOR]

We have prepared titania aerogel and titania-coated silica aerogel incorporating thiol-capped Au nanoparticles. Both composite materials showed high CO oxidation activity after they were calcined at 673 K. Compositional and morphological changes driven by calcination were evaluated with thermogravimetry and X-ray diffractometry. From the results, it was suggested that the nanoparticles transformed from a faulted to a near-regular FCC structure presumably in concert with the formation of firm contacts between the nanoparticles and the gel substrates. While the diameters of the Au particles in the titania aerogel considerably increased upon calcination, those in the titania-coated silica aerogel were almost unchanged. As a consequence, the latter composite aerogel showed higher activity for oxidation of CO. [ABSTRACT FROM AUTHOR]

Organic non-volatile memory devices were fabricated by embedding Au nanoparticle (NP)/ZnO nanorods (NRs) composite in an insulating poly (vinylpyrrolidone) as the active layer. The complete active materials were synthesized with an entire aqua solution process. Transmission electron microscopy images revealed that the Au NP/ZnO NRs composite exhibits an aster-like structure where Au NP is at the center while ZnO NRs are surrounding. Current-voltage (I-V) measurements of such device demonstrated electrical bistability with excellent on/off ratio of 4 × 103 under 1 V reading voltage. We attributed the high on/off ratio of the memory device to the large surface area of the Au NP/ZnO NRs composite where large amount of charges can be stored. In addition, the surrounding ZnO NRs act as spacers, which can effectively prevent the center gold nanoparticles from aggregation. Consequently, a low current leakage can be expected. Our study paved a way of employing a nanocomposite as a material for high performance organic memory devices. [ABSTRACT FROM AUTHOR]

Abstract: Radiation damage of self-assembled monolayers (SAMs), which are prototypes of thin organic layers and highly organized biological systems, has been investigated with synchrotron radiation at variable temperature. For the prototypes alkanethiolates on polycrystalline Au(111), and alkyls on monocrystalline Si(111), we have measured X-ray photoelectron spectroscopy (XPS), X-ray absorption (XAS), and stimulated desorption of ions and neutrals at 50 and at 300K. We find that the damage induced has a strong dependence on temperature. Two limiting cases can be identified. Reactions involving movement or transport of single atoms (e.g., desorption of H+) and local rearrangement (Crmation) proceed nearly independently of temperature. On the other hand, reactions requiring transport of heavy fragments (desorption of large neutral chain fragments, total material loss, formation of disulfide species requiring movement of large chains) are efficiently quenched by cooling. Probable mechanistic reasons will be discussed. In our opinion, these findings have broader implications as well. We foresee the combined use of temperature and irradiation by electrons or photons for advanced tailoring of self-assembled monolayers on surfaces. In addition, our results have direct bearing on cryogenic approaches in advanced electron and X-ray microscopy and spectroscopy of biological macromolecules and cells. [Copyright &y& Elsevier]