Dynamic properties of a suspension bridge constructed with trapezoidal steel box girders

Dynamic loads caused by wind and earthquakes are a critical issue when planning and designing large bridges. Studies on wind loads normally involved using wind-tunnel tests to investigate wind-resistance measures, including the section shape of stiffening girders for suspension bridges. Although some reports present the results of follow-up studies on completed bridges, so far a sufficient quantity of data has not accumulated to enable practical estimation of the oscillation properties of bridges.

This paper reports on the oscillation properties of an actual bridge, such as the damping factor and natural frequency, which were investigated by wind-tunnel tests of a scale model of the Ohshima Ohashi Bridge (one of a series of spans which form a link between Honshu and Shikoku in Japan) and oscillation tests of the actual bridge. The effects of center-stay cables, which are considered effective for improving wind resistance, were also investigated.     

Amorphous nanosilica induce endocytosis-dependent ROS generation and DNA damage in human keratinocytes

Background

The alveolar macrophage (AM) - first line of innate immune defence against pathogens and environmental irritants - constitutively expresses peroxisome-proliferator activated receptor γ (PPARγ). PPARγ ligand-induced activation keeps the AM quiescent, and thereby contributes to combat invaders and resolve inflammation by augmenting the phagocytosis of apoptotic neutrophils and inhibiting an excessive expression of inflammatory genes. Because of these presumed anti-inflammatory functions of PPARγ we tested the hypothesis, whether reduced functional receptor availability in mutant mice resulted in increased cellular and molecular inflammatory response during acute inflammation and/or in an impairment of its resolution.

Methods

To address this hypothesis we examined the effects of a carbon-nanoparticle (CNP) lung challenge, as surrogate for non-infectious environmental irritants, in a murine model carrying a dominant-negative point mutation in the ligand-binding domain of PPARγ (P465L/wt). Animals were instilled intratracheally with Printex 90 CNPs and bronchoalveolar lavage (BAL) was gained 24 h or 72 h after instillation to investigate its cellular and protein composition.

Results

Higher BAL cell numbers - due to higher macrophage counts - were found in mutants irrespective of treatment. Neutrophil numbers in contrast were slightly lower in mutants. Intratracheal CNP instillation resulted in a profound recruitment of inflammatory neutrophils into the alveolus, but genotype related differences at acute inflammation (24 h) and resolution (72 h) were not observed. There were no signs for increased alveolar-capillary membrane damage or necrotic cell death in mutants as determined by BAL protein and lactate-dehydrogenase content. Pro-inflammatory macrophage-derived cytokine osteopontin was higher, but galectin-3 lower in female mutants. CXCL5 and lipocalin-2 markers, attributed to epithelial cell stimulation did not differ.

Conclusions

Despite general genotype-related differences, we had to reject our hypothesis of an increased CNP induced lung inflammation and an impairment of its resolution in PPARγ defective mice. Although earlier studies showed ligand-induced activation of nuclear receptor PPARγ to promote resolution of lung inflammation, its reduced activity did not provide signs of resolution impairment in the settings investigated here.     

Polymeric ionic liquid membranes as electrolytes for lithium battery applications

A new kind of polymeric ionic liquid (PIL) membrane based on guanidinium ionic liquid (IL) with ester and alkyl groups was synthesized. On addition of guanidinium IL, lithium salt, and nano silica in the PIL, a gel PIL electrolyte was prepared. The chemical structure of the PIL and the properties of gel electrolytes were characterized. The ionic conductivity of the gel electrolyte was 5.07 × 10⁻⁶ and 1.92 × 10⁻⁴ S cm⁻¹ at 30 and 80 °C, respectively. The gel electrolyte had a low glass transition temperature (T _g ) under −60 °C and a high decomposition temperature of 310 °C. When the gel polymer electrolyte was used in the Li/LiFePO₄ cell, the cell delivered 142 mAh g⁻¹ after 40 cycles at the current rates of 0.1 C and 80 °C.     

Co2+-Substitution Effect in Ce-TZP/La M-type Hexaferrite Composites

A Ce-TZP/platelike La(Co(Fe_0.9Al_0.1)₁₁)O₁₉ composite was synthesized in situ while sintering from a mixture of Ce-TZP, La(Fe_0.9Al_0.1)O₃, Fe₂O₃, Al₂O₃, and CoO powders. Platelike La(Co(Fe_0.9Al_0.1)₁₁)O₁₉ crystals were grown in a dense Ce-TZP matrix after sintering at temperatures of 1200°–1350°C. The temperature range for sintering Ce-TZP/La(Fe,Al)₁₂O₁₉ composites was expanded widely by substituting Co²⁺ ions for Fe²⁺ ions in its structure. The highest value of the bending strength of the Ce-TZP/La(Co(Fe_0.9Al_0.1)₁₁)O₁₉ composites was 880 MPa, which was higher than that of the Ce-TZP/La(Fe,Al)₁₂O₁₉ composite (780 MPa) and Ce-TZP (513 MPa). The saturation magnetization of the Ce-TZP/La(Co(Fe_0.9Al_0.1)₁₁)O₁₉ composite was a constant value of 7.7 emu/g after the composite was sintered at 1200°–1350°C.     

Characterization of Schottky barrier diodes on a 0.5-inch single-crystalline CVD diamond wafer

In this study, Schottky barrier diodes were fabricated on a 0.5-inch single-crystalline diamond wafer, and the quality of the wafer as well as the performance of the devices were characterized. A rocking curve map indicated that the FWHM of the central 8 × 8-mm region was 10–50 arc sec, which is similar to that of high-quality HPHT single-crystalline diamond. The fabricated pVSBDs on the p^?/p⁺ stacked layer showed a high operation limit for the electrical field, with the mean value of this limit being higher than 2.5 MV/cm when the electrode was smaller than 300 µm. The performance of the devices seemed to be associated with the quality of the wafer. This indicates that the leakage current of a device is determined by the quality of the diamond wafer on which it is fabricated.     

Mechanism of N2O decomposition over a Rh black catalyst studied by a tracer method: The reaction of N2O with O(a)

N₂O decomposition on an unsupported Rh catalyst has been studied using tracer technique in order to reveal the reaction mechanism. N₂¹⁶O was pulsed onto ¹⁸O/oxidized Rh catalyst at 220°C and desorbed O₂ molecules (m/e=32,34,36) were monitored by means of mass spectrometer. The ¹⁸O fraction in the desorbed dioxygen was the same value as that on the surface oxygen. The result shows that the O₂ molecules desorb via Langmuir–Hinshelwood mechanism, i.e., the desorption of dioxygen through the recombination of adsorbed oxygen. On the other hand, TPD measurements in He showed that desorption of oxygen from the Rh black catalyst occurred at the higher temperatures. Therefore, reaction-assisted desorption of oxygen during N₂O decomposition reaction at the low temperature was proposed.     

Wear properties of silicon nitride in rolling contact

The wear properties of silicon nitride were examined in dry rolling contact.

The wear coefficient of silicon nitride in pure rolling was of the order of 10⁻⁶ at the initial stage of wear and of the order of 10⁻⁸ at the steady stage of wear under hertzian pressures of 1.06, 1.30, 1.50 and 1.83 GPa.

The wear coefficient of silicon nitride in rolling-sliding was of the order of 10⁻³ under hertzian pressures of 1.06, 1.50 and 1.83 GPa.

The original grinding marks were decreased by the initial wear. Then a very smooth surface appeared in the steady state and its centre-line average roughness R_a was 0.02 μm.

In contrast, pitting and the adhesive accumulation of thin film debris on the surface started to occur in the steady stage of wear.

Three typical types of wear debris were distinguished. One of these, which was a glassy film, was confirmed to have an SiO₂ structure.     

An 8-bit 2-ns monolithic DAC

An 8-bit resolution ultrahigh-speed monolithic digital-to-analog converter (DAC) is fabricated using super self-aligned process technology. In order to improve dynamic accuracy, which is determined by settling speed, clock feedthrough noise, and glitch, a number of circuit technologies are developed including a rise- and fall-time control switch driver, a low-noise flip-flop, and a differential buffer configuration. In addition, a chip assembly technology using a multilayer ceramic substrate is developed. The DAC exhibits a settling time to 8-bit accuracy of about 2 ns, a maximum conversion rate of 1 GHz, a glitch energy of 2 ps-V, and a 10-bit linearity error accuracy without trimming     

Transient photoinduced 'hidden' phase in a manganite

Photoinduced phase transitions are of special interest in condensed matter physics because they can be used to change complex macroscopic material properties on the ultrafast timescale. Cooperative interactions between microscopic degrees of freedom greatly enhance the number and nature of accessible states, making it possible to switch electronic, magnetic or structural properties in new ways. Photons with high energies, of the order of electron volts, in particular are able to access electronic states that may differ greatly from states produced with stimuli close to equilibrium. In this study we report the photoinduced change in the lattice structure of a charge and orbitally ordered Nd(0.5)Sr(0.5)MnO(3) thin film using picosecond time-resolved X-ray diffraction. The photoinduced state is structurally ordered, homogeneous, metastable and has crystallographic parameters different from any thermodynamically accessible state. A femtosecond time-resolved spectroscopic study shows the formation of an electronic gap in this state. In addition, the threshold-like behaviour and high efficiency in photo-generation yield of this gapped state highlight the important role of cooperative interactions in the formation process. These combined observations point towards a 'hidden insulating phase' distinct from that found in the hitherto known phase diagram.