Quantitative trait loci associated with promoting effects of sodium L-ascorbate on two-stage bladder carcinogenesis in rats

In the two-stage rat bladder carcinogenesis model using N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) as an initiator and sodium L-ascorbate (SA) as a promoter, we found a notable strain difference between F344/DuCrj (F344) and WS/Shi (WS) rats in susceptibility to the promoting effect of SA. Twenty each of F344, WS and reciprocal F1 hybrid rats were given 0.05% BBN in their drinking water for 4 weeks and then a basal diet with (BBN-SA group) or without (BBN group) a 5% SA supplement for 32 weeks. In F344 and also in reciprocal F1 hybrids, the number of tumors per rat was significantly higher in the BBN-SA group than in the BBN group (P < 0.0001). In contrast, WS rats were not significantly affected by either treatment (P = 0.8). These findings indicate that F344 rats are highly susceptible to the promoter effect of SA, but WS rats are not. Linkage analysis of 108 WSx (WS x F344) F1 backcrosses revealed that this difference was related to a quantitative trait locus mapped on rat Chr. 17 (maximum LOD score, 3.86) named Bladder Tumor Susceptible-1 and possibly another locus on Chr. 5 (maximum LOD score, 2.39). This study has provided the first evidence that host genes influence the risk of bladder cancer development.     

Regeneration across preserved peripheral nerve grafts

The potential to store nerve grafts for a prolonged period of time was assessed in a rat sciatic nerve model. Three-centimeter syngeneic nerve grafts were stored in Belzer/University of Wisconsin cold storage solution at different temperatures (5 degrees C, 22 degrees C, or 37 degrees C) for varying time periods (6 h, 24 h, or 3 weeks) prior to transplantation. Functional assessment using serial walking track analyses revealed no difference between storage times and temperatures. At 14 months postengraftment, the conduction velocities and the number of myelinated fibers that had regenerated across all grafts stored at 5 degrees C for all time periods tested were superior to grafts stored at either 22 degrees C or 37 degrees C. Nerve grafts stored for up to 3 weeks at 5 degrees C acted as effective conduits for proximal regenerating fibers and resulted in histologic, electrophysiologic, and functional results equivalent to fresh nerve grafts. Nerve graft storage may be applicable to nerve allografts and potentially provide allograft material that requires reduced or no associated host immunosuppression.     

Analytical formulas for modulation responses of semiconductor DFBlasers

Analytical expressions for the modulation responses of semiconductor DFB lasers are derived from a rigorous standing-wave rate equation formulations. With proper approximations, these expressions are reduced to simple and insightful formulas, similar to those obtained from the conventional rate equations. Salient features of the DFB lasers, such as complex-couplings, phase-shifts, facet conditions, as well as variations of carrier and photon densities along the cavity caused by the longitudinal hole-burning, are considered in these approximate formulas. It is demonstrated that the modulation responses, predicted by the simple formulas are in excellent agreement with the exact solutions     

Side-mode suppression mechanism of gain-coupled DFB lasers with periodically etched quantum wells

The effect of the gain and index coupling on the side-mode suppression ratio (SMSR) is studied for gain-coupled DFB lasers with periodically etched quantum wells. An accurate expression for the SMSR based on the amplified spontaneous emission model is used with the local-normal-mode transfer-matrix method. The mechanism for the strong single-mode stability of the gain-coupled DFB lasers is explained by the difference between the effective gain and loss of the Bloch waves in the grating structures. This new view clearly shows the advantage of the gain-coupled DFB lasers in terms of single-mode stability.     

1.3-μm GaInAsP/InP transverse-mode stabilized buried-crescentlasers by a new fabrication technique using a reactive ion beam etching

Transverse-mode-stabilized, 1.3-μm, GaInAsP/InP, buried-crescent (BC) lasers fabricated using a reactive ion beam etching (RIBE) technique are presented. Yields of single-transverse-mode operation as high as 95% are achieved with low threshold currents of 11-25 mA. Transverse-mode stability under both high-power and long-term operation (50°C, 20 mW, 1000 h) is demonstrated. A coupling efficiency into a single-mode fiber of 63% and a coupled power of 40 mW at 160 mA are achieved. Stable continuous-wave operation is also confirmed under a constant power of 5 mW (50 and 70°C) and 20 mW (50°C) in an aging test     

Prevention of small black spots on sugar-coated tablets containing aluminum acetylsalicylic acid

Sugar-coated tablets containing aluminum acetylsalicylate gradually developed black spots on their surface. A factorial experiment was performed based on an L32 orthogonal array table in an attempt to halt this phenomenon. The factor responsible proved to be talc used to formulate the smooth coating layer over the subcoating layer containing aluminum acetylsalicylate. When HCl-treated talc was used as a filler for the smoothing layer, the black spots were markedly decreased. The spotting mechanism was considered to be due to hydrolysis of aluminum acetylsalicylate in the subcoating layer to salicylic acid and acetic acid, which sublimated into the pores of the smoothing layer. Then, ferrous ion substituted from magnesium ion in the talc molecule center was extracted by salicylic acid, acetic acid, and moisture. Finally, the ferrous ion was oxidized to ferric ion, and this produced an Fe³⁺ chelate compound together with salicylic acid.     

Highly conductive ZnO films with high near infrared transparency

We present an approach for deposition of highly conductive nominally undoped ZnO films that are suitable for the n‐type window of low band gap solar cells. We demonstrate that low‐voltage radio frequency (RF) biasing of growing ZnO films during their deposition by non‐reactive sputtering makes them as conductive as when doped by aluminium (ρ≤1·10⁻³Ω cm). The films prepared with additional RF biasing possess lower free‐carrier concentration and higher free‐carrier mobility than Al‐doped ZnO (AZO) films of the same resistivity, which results in a substantially higher transparency in the near infrared region (NIR). Furthermore, these films exhibit good ambient stability and lower high‐temperature stability than the AZO films of the same thickness. We also present the characteristics of Cu(InGa)Se₂, CuInSe₂ and Cu₂ZnSnSe₄‐based solar cells prepared with the transparent window bilayer formed of the isolating and conductive ZnO films and compare them to their counterparts with a standard ZnO/AZO bilayer. We show that the solar cells with nominally undoped ZnO as their transparent conductive oxide layer exhibit an improved quantum efficiency for λ > 900 nm, which leads to a higher short circuit current density J_SC. This aspect is specifically beneficial in preparation of the Cu₂ZnSnSe₄ solar cells with band gap down to 0.85 eV; our champion device reached a J_SC of nearly 39 mAcm⁻², an open circuit voltage of 378mV, and a power conversion efficiency of 8.4 %. Copyright © 2015 John Wiley & Sons, Ltd.     

Introduction to the Special Issue on Causal Discovery

Many empirical sciences, including the social sciences and life sciences, aim to study causal relationships. Researchers in these fields need computational methods for analyzing observed data and identifying causal structures among a set of variables. Such computational methods enable researchers to draw conclusions on the basis of both their assumptions and the observed data. Moreover, these methods are useful for developing hypotheses on causal relations, designing future observational studies, and planning future experimental studies that can potentially provide stronger evidence of estimated causal relations.

The objective of this special issue is to present an up-to-date overview of causal discovery methods, which have witnessed rapid advancements in recent years. The chief editor and guest editors invited the following three survey papers on various hot topics related to causal discovery:

     

IR Practical Extinction Coefficients of Water in Alkali Lime Silicate Glasses Determined by Nuclear Reaction Analysis

Infrared spectroscopy (IR) is widely used to determine the water concentration in glasses, whereas determination of the IR practical extinction coefficient is necessary to deduce the absolute water concentration of glasses on the basis of Beer–Lambert law. From the nuclear reaction analysis data, the IR practical extinction coefficients of water were successfully determined for the alkali lime silicate glasses with different levels of sodium/potassium cation (Na/K) ratio. The two‐band method is well‐known to be useful for the determination of the water concentration in some alkali lime silicate glasses. It is proved here that the two‐band method is not applicable to the variety of composition for alkali lime silicate and soda lime aluminosilicate glasses, whereas it is valid for the similar composition of soda lime silicate glasses [SLS: Composition (in mol%) 16Na₂O·10CaO·74SiO₂]. The single‐band procedure with the IR practical extinction coefficient is crucial for the determination of the precise water concentration in the wide variety of glass composition although the determination of the IR practical extinction coefficient is troublesome. It also appears that the ion radius of alkali affects the IR practical extinction coefficient and the chemical state of OH group in glasses.