Efficient one-pot synthesis of α-aminophosphonates from aldehydes and ketones catalyzed by ytterbium(III) triflate

An efficient three component one-pot synthesis of N-silylated α-aminophosphonates and α,α-disubstituted α-aminophosphonates was developed using Yb(OTf)₃ as a catalyst at room temperature under mild conditions.     

A Q2Q1 finite element/level‐set method for simulating two‐phase flows with surface tension

A Q2Q1 (quadratic velocity/linear pressure) finite element/level‐set method was proposed for simulating incompressible two‐phase flows with surface tension. The Navier–Stokes equations were solved using the Q2Q1 integrated FEM, and the level‐set variable was linearly interpolated using a ‘pseudo’ Q2Q1 finite element when calculating the density and viscosity of a fluid to avoid an unbounded density/viscosity. The advection of the level‐set function was calculated through the Taylor–Galerkin method, and the direct approach method is employed for reinitialization. The proposed method was tested by solving several benchmark problems including rising bubbles exhibiting a large density difference and the surface tension effect. The numerical results of the rising bubbles were compared with the existing results to validate the benchmark quantities such as the centroid, circularity, and rising velocity. Furthermore, we focused our attention mainly on mass conservation and time‐step. We observed that the present method represented a convergence rate between 1.0 and 1.5 orders in terms of mass conservation and provided more stable solutions even when using a larger time‐step than the critical time‐step that was imposed because of the explicit treatment of surface tension. Copyright © 2011 John Wiley & Sons, Ltd.     

Large-area graphene synthesis and its application to interface-engineered field effect transistors

This article reviews recent advances in the large-area synthesis of graphene sheets and the applications of such sheets to graphene-based transistors. Graphene is potentially useful in a wide range of practical applications that could benefit from its exceptional electrical, optical, and mechanical properties. Tremendous effort has been devoted to overcoming several fundamental limitations of graphene, such as a zero band gap and a low direct current conductivity-to-optical conductivity ratio. The intrinsic properties of graphene depend on the synthetic and transfer route, and this dependence has been intensively investigated. Several representative reports describing the application of graphene as a channel and electrode material for use in flexible transparent transistor devices are discussed. A fresh perspective on the optimization of graphene as a 2D framework for crystalline organic semiconductor growth is introduced, and its effects on transistor performance are discussed. This critical review provides insights and a new perspective on the development of high-quality large-area graphene and the optimization of graphene-based transistors.     

Unified Noncrossing Multiple Quantile Regressions Tree

In this article, we consider the estimation problem of a tree model for multiple conditional quantile functions of the response. Using the generalized, unbiased interaction detection and estimation algorithm, the quantile regression tree (QRT) method has been developed to construct a tree model for an individual quantile function. However, QRT produces different tree models across quantile levels because it estimates several QRT models separately. Furthermore, the estimated quantile functions from QRT often cross each other and consequently violate the basic properties of quantiles. This undesirable phenomenon reduces prediction accuracy and makes it difficult to interpret the resulting tree models. To overcome such limitations, we propose the unified noncrossing multiple quantile regressions tree (UNQRT) method, which constructs a common tree structure across all interesting quantile levels for better data visualization and model interpretation. Furthermore, the UNQRT estimates noncrossing multiple quantile functions simultaneously by enforcing noncrossing constraints, resulting in the improvement of prediction accuracy. The numerical results are presented to demonstrate the competitive performance of the proposed UNQRT over QRT. Supplementary materials for this article are available online.     

Efficient evaluation of Casimir force in arbitrary three-dimensional geometries by integral equation methods

In this Letter, we generalized the surface integral equation method for the evaluation of Casimir force in arbitrary three-dimensional geometries. Similar to the two-dimensional case, the evaluation of the mean Maxwell stress tensor is cast into solving a series of three-dimensional scattering problems. The formulation and solution of the three-dimensional scattering problems are well-studied in classical computational electromagnetics. This Letter demonstrates that this quantum electrodynamic phenomenon can be studied using the knowledge and techniques of classical electrodynamics.     

An improved synthesis of quinolines from β‐bromovinyl aldehydes and primary arylamines in the presence of a palladium catalyst

β‐Bromovinyl aldehydes are effectively cyclized with primary arylamines in DMF at 110 °C in the presence of a catalytic amount of a palladium catalyst to give the corresponding quinolines in high yields. Copyright © 2010 John Wiley & Sons, Ltd.     

Portable capillary electrophoresis system for identification of cattle breeds based on DNA mobility

A portable CE system was developed for the identification of cattle breeds. The system had a width of 44 cm, depth of 27 cm, height of 13 cm, and a weight of only ∼8 kg and included an LIF detector, with everything integrated into a small box. The specific sizes of genes were quickly separated and detected with a high sensitivity based on the difference in the DNA mobility using a diode‐pumped solid‐state LIF detector. Using this system, the 100‐bp DNA ladder was analyzed under a 1.0% PVP (M_r=300 000) sieving gel matrix in a fused silica capillary with LODs of 4.4–13.0 pg/μL (S/N=3) for 100–3000 bp DNAs, which indicates ten times improved value than other commercialized portable CE system. The migration times and the peak areas showed good reproducibilities with relative standard deviations that were less than 0.49 and 1.3% (n=5), respectively. Based on the difference in the DNA mobility of the microsatellite and SNP markers, Korean cattle and Holstein were exactly identified as the model cattle breeds within 32 and 3.5 min, respectively.     

A new approach to desketoraloxifene analogs from oxygen-bearing 3-iodobenzo[b]thiophenes prepared via iodocyclization

A formal total synthesis of the benzothiophene selective estrogen receptor modulator (SERM) desketoraloxifene and analogs has been accomplished from alkynes bearing electron-rich aromatic rings by electrophilic cyclization using I₂. This approach affords oxygen-bearing 3-iodobenzo[b]thiophenes in excellent yields, which are easily further elaborated using a two-step approach involving Suzuki-Miyaura and Mitsunobu coupling reactions.     

High power LiCoO2 cathode materials with ultra energy density for Li-ion cells

Hydrothermally prepared 100 nm-sized LiCoO₂ with a plate morphology packed in a crucible resulted in 40 μm-sized particles that consisted of aggregated < 1 micron-sized particles after annealing at 900 °C for 3 h. In the condition where the optimized electrode pore volume was 20%, 4.1 g/cc of electrode density was obtained, which corresponded to 3 Wh/cc, which is the highest value among the cathode materials. Furthermore, the LiCoO₂ showed excellent capacity retention of 78% after 290 cycles in a Li-ion cell under 7 C rate cycling.