Synergism between 2,3,7,8-tetrachlorodibenzo-p-dioxin and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone on lung tumor incidence in mice

Although 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is classified as a human carcinogen, TCDD only induced oxidative DNA damages. In our present study, we combined TCDD with 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) to investigate their tumorigenic effects on lung tumor formation in A/J mice. Application of NNK at a tumorigenic dose (2 mg/mouse) induced lung adenoma in both male and female A/J mice. Neither application of NNK at a non-tumorigenic dose (1 mg/mouse) nor repeated application of TCDD alone increased tumor incidence. Following the single injection of NNK at a non-tumorigenic dose (1 mg/mouse), repeated application of TCDD significantly increased the lung tumor incidence in female, but not in male, A/J mice 24 weeks later. Utilizing the real-time RT-PCR array, we found that P16 mRNA was significantly reduced in female lung, but not male lung, of NNK/TCDD co-treated A/J mice. With immunohistochemical staining, we confirmed that nuclear P16 protein was reduced in the lungs of NNK/TCDD co-treated female mice. These data suggest that P16 reduction at least partially contributed to synergistic effects of TCDD in lung tumorigenesis.     

Thermal Spray Maps: Material Genomics of Processing Technologies

There is currently no method whereby material properties of thermal spray coatings may be predicted from fundamental processing inputs such as temperature-velocity correlations. The first step in such an important understanding would involve establishing a foundation that consolidates the thermal spray literature so that known relationships could be documented and any trends identified. This paper presents a method to classify and reorder thermal spray data so that relationships and correlations between competing processes and materials can be identified. Extensive data mining of published experimental work was performed to create thermal spray property-performance maps, known as “TS maps” in this work. Six TS maps will be presented. The maps are based on coating characteristics of major importance; i.e., porosity, microhardness, adhesion strength, and the elastic modulus of thermal spray coatings.     

Biodegradable Blends Prepared from Polycaprolactone and Poly(glutamic acid): Structure,Thermal Properties,and Biodegradability

Biodegradable polycaprolactone/poly(glutamic acid) (PCL/PGA) blends were prepared by a melt blending method. Additionally, acrylic acid-grafted polycaprolactone (PCL-g-AA) was studied as an alternative to PCL. The samples were characterized using Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), an Instron mechanical tester, and scanning electron microscopy (SEM). Because of poor compatibility between PCL and PGA, the mechanical properties of PCL/PGA blends were worse than of PCL alone. The PCL-g-AA/PGA blends had obviously improved mechanical properties over PCL/PGA ones, and the former provided a plateau tensile strength at break when the PGA content was up to 20 wt%. Biodegradation tests of blends were also conducted in a soil environment; the results showed that the mass of blends declined by about the PGA content within 4 weeks.     

Resonant‐Enhanced Full‐Color Emission of Quantum‐Dot‐Based Display Technology Using a Pulsed Spray Method

Colloidal quantum‐dot light‐emitting diodes (QDLEDs) with the HfO₂/SiO₂‐distributed Bragg reflector (DBR) structure are fabricated using a pulsed spray coating method. Pixelated RGB arrays, 2‐in. wafer‐scale white light emission, and an integrated small footprint white light device are demonstrated. The experimental results show that the intensity of red, green, and blue (RGB) emission exhibited considerable enhancement because of the high reflectivity in the UV region by the DBR structure, which subsequently increases the use in the UV optical pumping of RGB QDs. A pulsed spray coating method is crucial in providing uniform RGB layers, and the polydimethylsiloxane (PDMS) film is used as the interface layer between each RGB color to avoid cross‐contamination and self‐assembly of QDs. Furthermore, the chromaticity coordinates of QDLEDs with the DBR structure remain constant under various pumping powers in the large area sample, whereas a larger shift toward high color temperatures is observed in the integrated device. The resulting color gamut of the proposed QDLEDs covers an area 1.2 times larger than that of the NTSC standard, which is favorable for the next generation of high‐quality display technology.     

Linear regression‐based delay‐bounded routing protocols for VANETs

Routing protocols for vehicular ad hoc networks (VANETs) have attracted a lot of attention recently. Most of the researches emphasize on minimizing the end‐to‐end delay without paying attention to reducing the usage of radio. This paper focuses on delay‐bounded routing, whose goal is to deliver messages to the destination within user‐defined delay and to minimize the usage of radio because radio spectrum is a limited resource. The messages can be delivered to the destination by the hybrid of data muling (carried by the vehicle) and forwarding (transmitted through radio). In the existing protocol, a vehicle may only switch the delivery strategy (muling or forwarding) at an intersection according to the available time of the next road segment, which is between the current intersection and the next intersection. To improve previous works, our protocol uses linear regression to predict the available time and the traveling distance, and thus, the vehicle can switch to a proper delivery strategy at a proper moment and can reduce the number of relays by radio. Our protocol contains two schemes: the greedy and centralized schemes. The greedy scheme uses only the current sampling data to predict the available time and decide when to switch the delivery strategy, whereas the centralized scheme uses the global statistical information to choose a minimum‐cost path. Simulation results justify the efficiency of the proposed protocol. Copyright © 2011 John Wiley & Sons, Ltd.     

Organo-soluble phosphinated polyimides from asymmetric diamines

Two new asymmetric diamines (1-2) were prepared via a facile, one-pot procedure. Based on diamine (1-2), a series of asymmetric polyimides (3-4) were prepared in NMP/xylene by high-temperature solution polymerization. The resulting polyimides are readily soluble in some organic solvents, and can be solution casted into flexible and creasable films. An intramolecular charge complex mechanism was proposed to the structure-optical transparency relationship. Polyimides 3-4 display high-Tg (319-401 °C), high moduli (2.40-7.20 GPa), moderate coefficient of thermal expansion (38-53 ppm/°C), and excellent flame retardancy. These results show that the introduction of the asymmetric structure is an effective way to improve organo-solubility while maintaining thermal properties. Because of these properties, polyimides 3-4 can be considered as excellent high-Tg and flame-retardant materials for microelectronic applications.     

Kirkendall porosity in barium titanate–strontium titanate diffusion couple

Inter-diffusion between perovskites BaTiO₃ and SrTiO₃ diffusion couple has been studied by determining the crystalline phases and analyzing the microchemistry and microstructure of undoped BaTiO₃–SrTiO₃ stacks sintered at 1250 °C in air. The Kirkendall effect manifested by: (1) an inter-diffusion zone containing (Ba_1−xSr_x)TiO₃ and (Sr_1−xBa_x)TiO₃ solid solutions, (2) the migration of the initial BaTiO₃–SrTiO₃ interface, and (3) the Kirkendall porosity was observed. The inter-diffused regions on both sides of the initial interface contain grains exhibiting the characteristic core–shell structure with distinctive solute contents between core and shell. TiO₂-rich polytitanates, notably Ba₄Ti₁₃O₃₀ and Ba₆Ti₁₇O₄₀ containing a minor amount of Sr from inter-diffusion, have been detected at the BaTiO₃ side near the initial BaTiO₃–SrTiO₃ interface. An analogy between the BaTiO₃–SrTiO₃ diffusion couple and Kirkendall's original α-brass-Cu couple is presented.     

Gallium Phosphide Solar Cell Structures with Improved Quantum Efficiencies

Journal of Electronic Materials - Gallium phosphide (GaP) solar cell structures with improved quantum efficiencies were realized using a modified liquid phase epitaxy (LPE) technique and diodes...     

Solar water oxidation in sputter-deposited nanocrystalline WO3 photoanodes via tuning of Ar:O2 flow rate combinations

Thin film WO₃ photoanodes were prepared by reactive sputtering in Ar and O₂ gas mixtures of various flow rate combinations. Furnace annealed films were nanocrystalline monoclinic WO₃ with (002), (020) and (200) plane orientations. Water oxidation in 0.33 M H₂SO₄ electrolyte under simulated solar illumination showed that photoanodes deposited in highest Ar and O₂ flow rate combinations exhibited highest photocurrent of 4.1 mA cm⁻² (at 1.3 V vs Ag/AgCl) compared to 3–3.8 mA cm⁻² for photoanodes deposited in lower flow rate combinations. The higher photocurrents were ascribed to lower bulk resistivity and charge transfer resistance at the WO₃/electrolyte interface. These photoanodes consisted of randomly oriented (002), (020) and (200) planes in contrast to the preferentially orientated (002) and (200) planes of photoanodes which were highly resistive with poorer photocurrent responses. These results were interpreted in terms of the effects of Ar:O₂ flow rate combinations on the distribution of oxygen vacancies and formation of crystallographic shear planes in the sputtered films.     

Katanin-Dependent Microtubule Ordering in Association with ABA Is Important for Root Hydrotropism

Root hydrotropism refers to root directional growth toward soil moisture. Cortical microtubule arrays are essential for determining the growth axis of the elongating cells in plants. However, the role of microtubule reorganization in root hydrotropism remains elusive. Here, we demonstrate that the well-ordered microtubule arrays and the microtubule-severing protein KATANIN (KTN) play important roles in regulating root hydrotropism in Arabidopsis. We found that the root hydrotropic bending of the ktn1 mutant was severely attenuated but not root gravitropism. After hydrostimulation, cortical microtubule arrays in cells of the elongation zone of wild-type (WT) Col-0 roots were reoriented from transverse into an oblique array along the axis of cell elongation, whereas the microtubule arrays in the ktn1 mutant remained in disorder. Moreover, we revealed that abscisic acid (ABA) signaling enhanced the root hydrotropism of WT and partially rescued the oryzalin (a microtubule destabilizer) alterative root hydrotropism of WT but not ktn1 mutants. These results suggest that katanin-dependent microtubule ordering is required for root hydrotropism, which might work downstream of ABA signaling pathways for plant roots to search for water.