2,397 research outputs found
Syntheses, Structures, and Electroluminescence of New Blue/Green Luminescent Chelate Compounds: Zn(2-py-in)<sub>2</sub>(THF), BPh<sub>2</sub>(2-py-in), Be(2-py-in)<sub>2</sub>, and BPh<sub>2</sub>(2-py-aza) [2-py-in = 2-(2-pyridyl)indole; 2-py-aza = 2-(2-pyridyl)-7-azaindole]
No full textFour novel blue/green luminescent compounds, Zn(2-py-in)2(THF) (1), BPh2(2-py-in) (2), Be(2-py-in)2 (3), and BPh2(2-py-aza) (4), where 2-py-in = 2-(2-pyridyl)indole and 2-py-aza = 2-(2-pyridyl)-7-azaindole, have been synthesized and fully characterized. The 2-py-in ligand and 2-py-aza ligand in the new
compounds are chelated to the central atom. Compounds 2−4 are air stable and readily sublimable, with a
melting point above 250 °C. In the solid state, compounds 1−4 have an emission maximum at λ 488, 516,
490, and 476 nm, respectively. The structures of compounds 2 and 4 are similar. The blue shift of emission
energy displayed by compound 4, in comparison to that of 2, is attributed to the presence of an extra nitrogen
atom in the 2-py-aza ligand as confirmed by ab initio calculations on compounds 2 and 4. Electroluminescent
devices of compounds 3 and 4 were fabricated by using N,N‘-di-1-naphthyl-N,N‘-diphenylbenzidine (NPB) as
the hole transporting layer, Alq3 (q = 8-hydroxyquinolato) as the electron transporting layer, and compound
3 or 4 as the light emitting layer. At 20 mA/cm2 the EL device of 3 has an external efficiency of 1.06 cd/A
while the EL device of 4 has an external efficiency of 2.34 cd/A, demonstrating that compounds 3 and 4 are
efficient and promising emitters in electroluminescent devices
Performance Enhancement of Conventional Polymer Solar Cells with TTF-py-Modified PEDOT:PSS Film as the Hole Transport Layer
No full textA thin
TTF-py film combined with PEDOT:PSS film was introduced
to enhance the device performance of conventional polymer solar cells.
The origin of the enhanced Jsc and fill
factor was systematically studied by SEM, AFM, contact angle, and
electrochemical impedance spectroscopy measurements. The morphological
improvement of TTF-py-modified film contributed to the decrease of
series loss. In addition, the charge recombination was effectively
suppressed as the interfacial contact of the modified transport layer
with the photoactive layer was enhanced as well. Being consistent
with the hole mobility test results, the calculated effective carrier
mass of TTF-py fitting to the band edge indicates high hole mobility
in the organic molecule direction and organic molecule accumulational
direction. The results indicate a promising approach by inserting
a TTF-py as a modified layer of PEDOT:PSS to promote the performance
of conventional polymer solar cells
rwest/RMG-Py: RMG-Cat version 1.0
No full text<p>This is the first release of the version of RMG-Py for Heterogeneous Catalysis, with the relevant modifications being made by C. Franklin Goldsmith and Richard H. West. It corresponds to a similar release of the RMG-database repository.</p>
Significance of early changes in the serum CA-125 antigen level on overall survival in advanced ovarian cancer
No full textObjective. The relationship between survival and early changes in the serum level of the CA-125 antigen in patients with advanced ovarian cancer remains poorly defined. Methods. To explore this issue, the serum CA-125 values from 101 patients with advanced ovarian cancer who participated in a Southwest Oncology Group trial (SWOG 8412), which compared the systemic delivery of cisplatin/cyclophosphamide vs. carboplatin/cyclophosphamide (both delivered every 28 days for 6 cycles) in suboptimal residual stage III and IV ovarian cancer, were evaluated. All patients in this analysis had CA-125 values available for at least 8 weeks following initiation of chemotherapy. Cox proportional hazards regression was used in multivariate analysis to determine the prognostic significance of the CA-125 concentration. Results. While pretreatment CA-125 values did not correlate with survival, the concentration of this tumor marker 8 weeks after initiation of therapy was a powerful independent prognostic factor. The median survivals for patients (n = 51) with a CA-125 35 U/ml, at this time point, were 26 months and 15 months, respectively (P = 0.0001). Further, women with serum CA-125 values 50% of their baseline value (P = 0.0003). Conclusion. Reduction in the serum CA-125 concentration over the initial two cycles of platinum-based chemotherapy is a powerful independent predictor of survival for patients with suboptimal stage III or IV ovarian cancer. Patients without significant declines in CA-125 after two cycles of platinum-based chemotherapy have a particularly poor prognosis. (c) 2006 Elsevier Inc. All rights reserved
Dynamic Compression Modulates Chondrocyte Proliferation and Matrix Biosynthesis in Chitosan/Gelatin Scaffolds
No full textAdaptive relevance feedback model selection for content-based image retrieval
No full text[[abstract]]Owing to the rapid development in computer and network technologies, the volumes of modern image repositories have been overwhelming. In this context, traditional image retrieval based on textual indexing is laborious, thus inviting the implementation of content-based image retrieval (CBIR). Relevance feedback (RF) is an iterative procedure which refines the content-based retrievals utilizing the user's RF marked on retrieved results. Recent research has focused on RF model space optimisation. In this paper, we propose an adaptive RF model selection framework which automatically chooses the best RF model with proper parameter values for the given query. The proposed method combines the visual space and model space approaches in order to simultaneously perform two learning tasks, namely, the query optimisation and model optimisation. The particle swarm optimisation (PSO) paradigm is applied to assist the learning tasks. Experimental results tested on a real-world image database reveal that the proposed method outperforms several existing RF approaches using different techniques. The convergence behaviour of the proposed method is empirically analysed.[[note]]SC
Microstrain in pyrope-grossular garnet solid solution at high pressure: a case study of Py(90)Gr(10) and Py(10)Gr(90) up to 15 GPa
No full textSingle-phase, well-sintered, translucent polycrystalline garnets with compositions of Py(90)Gr(10) and Py(10)Gr(90) were synthesized at 6 GPa and 1400 degrees C using a multi-anvil apparatus. X-ray diffraction (XRD) data for these garnet solid solutions were collected with both high-resolution synchrotron X-ray and standard laboratory X-ray sources. Analysis of the FWHM of the XRD peaks using Williamson-Hall plot yields microstrains around 0.12% for Py(90)Gr(10) and 0.09% for Py(10)Gr(90). The FWHM of Py(10)Gr(90) garnet as well as the derived microstrain remains constant up to 11 GPa, followed by a continuous increase to the experimental peak pressure 15 GPa caused by elastic strain in response to deviatoric/anisotropic stresses. The FWHM and microstrain for Py(90)Gr(10) remain constant to the measurement limit at 7 GPa. The microstrain of pyrope-grossular garnets exhibits a nonlinear dependence on composition, showing two peaks near Py(20)Gr(80) and Py(80)Gr(20), which may be associated with local structural heterogeneities arising from Mg and Ca substitution. Using a third-order Birch-Murnaghan equation of state, the bulk modulus is constrained to be Ie (0) = 171.8 +/- 2.1 GPa (with K-0(') fixed to 5.92) for Py(10)Gr(90) and Ie (0) = 174.3 +/- 2.5 GPa (with K-0(') fixed to 4.4) for Py(90)Gr(10), both of which are much larger than that for intermediate composition close to Py(50)Gr(50) but comparable to that for their corresponding end members. The relatively larger microstrain and higher bulk moduli for Py(10)Gr(90) and Py(90)Gr(10) garnets could be related to short-range ordering of Mg and Ca cations in garnet structure due to substitution, which results in different local environments for Mg and Ca cations along the pyrope-grossular solid solution.DOE/NNSA [DE-NA0002907]; NSF [EAR1524078]SCI(E)ARTICLE6377-3884
A new relevance feedback technique for iconic image retrieval based on spatial relationships
No full text[[abstract]]Due to the popularity of Internet and the growing demand of image access, the volume of image databases is exploding. Hence, we need a more efficient and effective image searching technology. Relevance feedback technique has been popularly used with content-based image retrieval (CBIR) to improve the precision performance, however, it has never been used with the retrieval systems based on spatial relationships. Hence, we propose a new relevance feedback framework to deal with spatial relationships represented by a specific data structure, called the 2D B(e)-string. The notions of relevance estimation and query reformulation are embodied in our method to exploit the relevance knowledge. The irrelevance information is collected in an irrelevant set to rule out undesired pictures and to expedite the convergence speed of relevance feedback. Our system not only handles picture-based relevance feedback, but also deals with region-based feedback mechanism, such that the efficacy and effectiveness of our retrieval system are both satisfactory. (C) 2008 Elsevier Inc. All rights reserved.[[note]]SC
Physicochemical Properties of Ionic Liquids [C(3)py][NTf2] and [C(6)py][NTf2]
No full textAir- and water-stable hydrophobic ionic liquids N-alkylpyridinium bis(trifluoromethylsulfonyl)imide ([C(n)py][NTf2], n = 3, 6) were synthesized. The density, surface tension, dynamic viscosity, and electrical conductivity of [C(6)py][NTf2] were measured in the range of T = (283.15 to 338.15) K. The density, dynamic viscosity, and electrical conductivity of [C(3)py][NTf2] were measured in the range of T = (308.15 to 338.15) K. The melting and glass transition temperatures of the two ILs were determined according to the differential scanning calorimetry (DSC). The physicochemical properties, including molecular volume, standard molar entropy, lattice energy, parachor, molar enthalpy of vaporization, interstice volume, interstice fraction, and thermal expansion coefficient, were estimated in terms of empirical and semiempirical equations, as well as the interstice model theory on the base of the experimental values. The dynamic viscosity and electrical conductivity values were fitted by Vogel-Fulcher-Tammann (VFT) and Arrhenius equations for [C(6)py][NTf2] and the Arrhenius equation for [C(3)py][NTE2]
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