Apodized surface-corrugated gratings with varying duty cycles

We present the first realization of a Bragg grating apodization based on a concatenation of different duty cycles. The gratings were fabricated in SiON planar waveguides. The reflected signal exhibits a sidelobe suppression better than -20 dB outside a bandwidth of 1.36 nm. At the same time the reflection is stronger than 99.9%, i.e., the resonant light is suppressed better than -30 dB in transmission over 0.22 nm. The gratings are perfectly suited to serve as the wavelength-selective element of a Mach-Zehnder add/drop filter     

Antitumor Effects of Orally Administered Rare Sugar D-Allose in Bladder Cancer

D-allose is a rare sugar that has been reported to up-regulate thioredoxin-interacting protein (TXNIP) expression and affect the production of intracellular reactive oxygen species (ROS). However, the antitumor effect of D-allose is unknown. This study aimed to determine whether orally administered D-allose could be a candidate drug against bladder cancer (BC). To this end, BC cell lines were treated with varying concentrations of D-allose (10, 25, and 50 mM). Cell viability and intracellular ROS levels were assessed using cell viability assay and flow cytometry. TXNIP expression was evaluated using Western blotting. The antitumor effect of orally administered D-allose was assessed using a xenograft mouse model. D-allose reduced cell viability and induced intracellular ROS production in BC cells. Moreover, D-allose stimulated TXNIP expression in a dose-dependent manner. Co-treatment of D-allose and the antioxidant L-glutathione canceled the D-allose-induced reduction in cell viability and intracellular ROS elevation. Furthermore, oral administration of D-allose inhibited tumor growth without adverse effects (p < 0.05). Histopathological findings in tumor tissues showed that D-allose decreased the nuclear fission rate from 4.1 to 1.1% (p = 0.004). Oral administration of D-allose suppressed BC growth in a preclinical mouse model, possibly through up-regulation of TXNIP expression followed by an increase in intracellular ROS. Therefore, D-allose is a potential therapeutic compound for the treatment of BC.     

Optimization‐based stability analysis of structures under unilateral constraints

This paper discusses an optimization‐based technique for determining the stability of a given equilibrium point of the unilaterally constrained structural system, which is subjected to the static load. We deal with the three problems in mechanics sharing the common mathematical properties: (i) structures containing no‐compression cables; (ii) frictionless contacts; and (iii) elastic–plastic trusses with non‐negative hardening. It is shown that the stability of a given equilibrium point of these structures can be determined by solving a maximization problem of a convex function over a convex set. On the basis of the difference of convex functions optimization, we propose an algorithm to solve the stability determination problem, at each iteration of which a second‐order cone programming problem is to be solved. The problems presented are solved for various structures to determine the stability of given equilibrium points. Copyright © 2008 John Wiley & Sons, Ltd.     

Group Selective Linear Polymerization of Vinyl Acrylate Using 19-Borabicyclo[3.3.1]nonane

Vinyl acrylate (VA) was polymerized with 9-borabicyclo[3.3.1]nonane (9-BBN) in tetrahydrofuran under argon at low temperatures (to -60°C). Hydroquinone and 2,6-di-tert-butyl-p-cresol had little effect on the polymerization. Addition of tetrachloromethane as a radical chain transfer agent did not lead to decrease in molecular weight of the polymer obtained. The initial rate of polymerization was proportional to [9-BBN]^0·91 and [VA]^1·37. The experimental results were indicative of non-radical properties of the propagating chain end. The polymer was soluble in organic solvents such as toluene, chloroform and N,N-dimethylformamide. The nuclear magnetic resonance measurements showed the presence of pendant vinyl groups in the polymer, indicating that only the acrylic double bond of VA reacted for polymerization to yield a linear polymer. Aniline retarded the polymerization and no polymer was formed in the presence of triethylamine. These inhibitory effects were explained on the basis of complex formation of 9-BBN with amines. This polymerization is discussed in terms of a non-radical mechanism. © of SCI.     

Polymerization of – Phenylmaleimide Initiated by 9-Borabicyclo[3.3.1]nonane

N-Phenylmaleimide (N-PMI) was polymerized by 9-borabicyclo[3.3.1] nonane (9-BBN) in tetrahydrofuran under argon at 0°C. The molecular weight distributions of the resulting polymers were around 1·1. The rate of poly-merization was proportional to [9-BBN]^1·18 and [N-PMI]^1·24. Hydroquinone had little effect on the rate of polymerization and on the molecular weight of the polymers obtained. Triethylamine completely inhibited the polymerization, and aniline with a relatively small pK_a value and zinc iodide effectively retarded the polymerization. The polymerization did not proceed either in polar dimethylformamide or in non-polar toluene. In polymerizations at temperatures higher than 60°C the conversions decreased. On the basis of the results, a non-radical mechanism was proposed for this polymerization. © of SCI.     

Relationship between surface chemistry and electrochemical behavior of LiNi1/2Mn1/2O2 positive electrode in a lithium-ion battery

The formation and the evolution of lithium-containing species on the surface of grains of a layered 4 V material such as LiNi_1/2Mn_1/2O₂ along the electrochemical cycling have been followed using ⁷Li MAS NMR, electrochemical impedance spectroscopy (EIS) and XPS. Materials displaying different specific surface areas and stored in different atmospheres have been investigated in order to study the influence of the surface/volume ratio and the influence of the initial surface state, respectively. It is shown that the presence of an initial interphase of Li₂CO₃ influences the electrochemical behavior of the electrode, emphasizing the importance of the history of the electrode prior cycling. ⁷Li MAS NMR experiments performed upon cycling indicate the formation of interphase species in reduction and their partial removal in oxidation, indicating the dynamic character of the interphase upon cycling. Combined NMR, EIS and XPS experiments show the strong influence of the electrode/electrolyte interphase evolution on the electrochemical performance. Such results lead us to draw conclusions on the optimal storage conditions of layered 4 V materials for Li-ion batteries such as LiNi_1/2Mn_1/2O₂.     

A mixed integer programming for robust truss topology optimization with stress constraints

This paper presents a mixed integer programming (MIP) formulation for robust topology optimization of trusses subjected to the stress constraints under the uncertain load. A design‐dependent uncertainty model of the external load is proposed for dealing with the variation of truss topology in the course of optimization. For a truss with the discrete member cross‐sectional areas, it is shown that the robust topology optimization problem can be reduced to an MIP problem, which is solved globally. Numerical examples illustrate that the robust optimal topology of a truss depends on the magnitude of uncertainty. Copyright © 2010 John Wiley & Sons, Ltd.     

POLYCYCLIC AROMATIC HYDROCARBONS OF DIESEL AND GASOLINE EXHAUST AND DNA ADDUCT DETECTION IN CALF THYMUS DNA AND LYMPHOCYTE DNA OF WORKERS EXPOSED TO DIESEL EXHAUST

Particles present in urban air pollution are mainly derived from diesel- and gasoline-fueled vehicles. Exhaust emission is able to cause several health effects in humans including mutagenicity and carcinogenicity. Polycyclic aromatic hydrocarbons (PAHs) were measured in diesel and gasoline particulate extracts and DNA binding to CT DNA (±S9 and ±XO) was investigated. A large difference in content of 14 PAHs in diesel and gasoline extracts was observed, showing higher concentration of 14 PAHs, 6 carcinogenic PAHs, benzo[a]pyrene (B[a]P) in diesel than in gasoline extracts. Selected PAH standards of B[a]P, benzo[c]fluoranthene (B[c]F), and 3-nitrobenzanthrone (NBA) were used in ³²P-postlabeling/polyacrylamide gel electrophoresis (PAGE) technique to identify CT DNA adducts formed by diesel particulate extracts. CT DNA adduct formation was higher for diesel extracts in comparison with gasoline extracts; however, no clear origin of DNA adducts derived from B[c]F-, 3-NBA-, B[a]P was detected. ³²P-postlabeling/PAGE was a useful assay for analyzing and identifying PAH-DNA adducts. Occupational exposure to particulate and volatile PAH concentrations were evaluated using personal air samples and lymphocyte DNA adducts as markers of exposure. Overall air PAH concentrations were low in all eight workplaces, consisting of 97% of vapor phase compounds. DNA adducts analyzed by ³²P-postlabeling assay were compared between the butanol and nuclease P1 enrichment procedures. Only in winter samples of exposed workers, butanol extraction revealed significantly higher adduct levels in comparison with those of control persons. No differences in adduct levels between exposed and control persons in summer were detected by using either butanol extraction or nuclease P1 treatment. Total concentrations of particulate and volatile PAHs measured in eight workplaces in winter showed a significant correlation with total DNA adducts analyzed in workers' lymphocytes (r = 0.852N = 8, p = .007).     

Development of OLED with high stability and luminance efficiency by co-doping methods for full color displays

We propose co-doping systems in emission layers of red and green organic light-emitting diodes (OLEDs). The luminance-voltage, luminous and power efficiency-voltage characteristics, operational stability, and the energy bands of materials were measured. In red OLED devices, we propose an emitting assist (EA) dopant for better luminance efficiency and power efficiency with pure red emission and improved operational stability. The EA dopant (rubrene) did not emit itself but assisted the energy transfer from a host (Alq) to an emitting dopant (DCJTB). By doping rubrene, the luminance efficiency increased from 1.7 to 4.3 cd/A (from 0.6 to 1.9 lm/W) with chromaticity of (x=0.64, y=0.36) unchanged. An improved lifetime was also observed. In green OLED devices, we introduced hole transporting material (NPB) into an emission layer for better charge injection balance. The green devices with the emitting dopant (C545T) achieved the luminance efficiency of 8.5 cd/A compared with 6.9 cd/A without NPB. We studied the co-doping methods and use of this approach for active-matrix full color display. The power consumption of white emission at 100 cd/m/sup 2/ was reduced by 32%. The effectiveness of these co-doping methods was demonstrated for practical applications.