Advanced Dicing Technology for Semiconductor Wafer—Stealth Dicing

ldquoStealth dicing (SD)rdquo was developed to solve inherent problems of a dicing process such as debris contaminants and unnecessary thermal damages on a work wafer. A completely dry process is another big advantage over other dicing methods. In SD, the laser beam power of transmissible wavelength is absorbed only around focal point in the wafer by utilizing the temperature dependence of the absorption coefficient of the wafer. The absorbed power forms a modified layer in the wafer, which functions as the origin of separation in the separation process. In this paper, we applied this method for an ultra-thin wafer. The reliability of devices that is diced by SD was confirmed.     

Natural Killer T Cells Are Involved in Atherosclerotic Plaque Instability in Apolipoprotein-E Knockout Mice

The infiltration and activation of macrophages as well as lymphocytes within atherosclerotic lesion contribute to the pathogenesis of plaque rupture. We have demonstrated that invariant natural killer T (iNKT) cells, a unique subset of T lymphocytes that recognize glycolipid antigens, play a crucial role in atherogenesis. However, it remained unclear whether iNKT cells are also involved in plaque instability. Apolipoprotein E (apoE) knockout mice were fed a standard diet (SD) or a high-fat diet (HFD) for 8 weeks. Moreover, the SD- and the HFD-fed mice were divided into two groups according to the intraperitoneal injection of α-galactosylceramide (αGC) that specifically activates iNKT cells or phosphate-buffered saline alone (PBS). ApoE/Jα18 double knockout mice, which lack iNKT cells, were also fed an SD or HFD. Plaque instability was assessed at the brachiocephalic artery by the histological analysis. In the HFD group, αGC significantly enhanced iNKT cell infiltration and exacerbated atherosclerotic plaque instability, whereas the depletion of iNKT cells attenuated plaque instability compared to PBS-treated mice. Real-time PCR analyses in the aortic tissues showed that αGC administration significantly increased expressional levels of inflammatory genes such as IFN-γ and MMP-2, while the depletion of iNKT cells attenuated these expression levels compared to those in the PBS-treated mice. Our findings suggested that iNKT cells are involved in the exacerbation of plaque instability via the activation of inflammatory cells and upregulation of MMP-2 in the vascular tissues.     

Combinational use of antibody affinities in an immunoassay for extension of dynamic range and detection of multiple analytes

Here, we describe the coordinated use of two antibodies with different affinities in a single immunoassay to extend the dynamic range and to enable detection of multiple analytes. The combination of dual antibodies was permitted with a flow-based assay at the antibody concentration below the dissociation constant, enabling affinity to govern the antibody-antigen binding. Both high and low affinity antibodies to estriol were used in combination to extend the range. The binding of each antibody was mutually independent and individually occurred over concentration ranges of 10 pM(-1) nM and 100 pM(-1) microM. The wide dynamic range of 10 pM(-1) microM was thus achieved as summation of the proportional signals to the total binding. When a combination of antibodies toward different antigens was used, it effectively detected multiple analytes within a mixture. In simultaneous analysis of a mixture of estradiol and estriol, the total signal was the sum of the binding signals from anti-estradiol and anti-estriol antibodies. In a further refinement, the individual antibodies were flowed through the flow cell sequentially, allowing the quantification of each binding signal within the combination. With this sequential format, measurement of the individual hormones in the range of 1.6 pM(-1) nM was shown. Furthermore, the same flow format was successfully applied to assay estriol and estradiol hormones in mixtures of six related compounds.     

Gel permeation chromatography using controlled-porosity glass. I. Polyacrylamide–formamide solution

The process of characterizing polyacrylamide and its partially hydrolyzed materials by gel permeation chromatography was examined. The use of controlled-porosity glass and formamide as the stationary phase and the eluent, respectively, resulted in chromatographic behavior in accord with the hydrodynamic volume concept for polyacrylamide fractions. The addition of a salt (KCl) to the eluent was found to retard the elution of the hydrolyzed polyacrylamide.     

ESTIMATION OF SERVICE LOADING FROM THE WIDTH AND HEIGHT OF FATIGUE STRIATIONS OF 2017-T4 A1 ALLOY

A case-study method is proposed to determine service loading from fracture surface striations. Although it is well known that striation spacing relates to the crack growth rate, it is considered impossible to determine maximum and minimum loads under service loading conditions, and which define the stress ratio R, from an analysis of the striation spacing. This paper presents a new method of determining the maximum and minimum loads which is based on the experimental fact that the relative height of a striation H to striation spacing s is strongly influenced by the stress ratio. The results of fatigue tests on 2017-T4 A1 alloy showed a definite correlation between these parameters. The difficulty of measuring striation height was overcome by taking the measurements in a scanning electron microscope after sectioning the specimens at a large inclined angle. Striations under a stress ratio R=?1 are compressed and flat, and the ratio H/s is small. With increasing R, the value of H/s becomes large. Therefore a standard laboratory test that determines the relationship between s and ΔK, and also between H/s and R enables one to estimate service loadings from fatigue fracture surfaces.     

High temperature fatigue crack growth in a cobalt base superalloy

The rates of fatigue crack propagation of a cobalt base superalloy (HS 188) were measured at 75, 1112, 1400 and 1600°F as a function of the range of the stress intensity factor ΔK. Test frequencies were 0.01, 0.1, 1 and 10 Hz. At each elevated temperature there is a critical frequency below which the crack growth rate is oxidation and creep dependent, increasing with decreasing frequency. The mode of fracture changes from transgranular at high frequencies to intergranular at low frequencies.     

Matrix metalloproteinase-2 inhibition and Zn2+-chelating activities of pyoverdine-type siderophores

Pyoverdine-type siderophores from fluorescent Pseudomonas species were purified by Zn2+-chelate chromatography, and their matrix metalloproteinase-2 (MMP-2) inhibition and metal-ion-chelating activities were studied. Structurally different pyoverdines showed different MMP-2 inhibition activities, and the inhibition activity was correlated with Zn2+-chelating activity. The IC50 value of a pyoverdine ((P113A1)-2, MW 1187) for MMP-2 was 0.27 microg/ml (0.23 microM).     

An immunoassay for small analytes with theoretical detection limits

A flow-based immunoassay that uses microspheres as the solid phase accomplished the theoretical limit of detectability achievable with the antibody. An equilibrated mixture of anti-estriol monoclonal antibody and estriol was briefly exposed to a bead pack containing immobilized estriol in a flow cell. A small portion of free antibody was separated rapidly from the mixture by binding it to immobilized hormone, but the antibody-hormone complex was kinetically excluded from binding. This rapid separation prevented shift in the equilibrium of the liquid phase binding. Signals were generated by labeling the separated antibodies on the beads with a Cy5-conjugated antispecies secondary antibody. By labeling after the separation step, perturbing the liquid-phase or solid-phase binding was prevented. This assay allowed the reduction of the concentration of primary antibody by continuously accumulating free antibody onto the beads prior to quantification and, thus, offered ideal conditions to achieve theoretical limits of detectability. The optimum achievable dynamic range of this immunoassay was 4-300 pM. Because the proportion of free anti-estriol antibody in the mixture was controlled by the Kd of the antibody-estriol interaction, when the concentration of the antibody was below the Kd, the smallest detectable estriol concentration approached the theoretical limit of detectability achievable with this antibody.