Characterization of MOVPE-grown p-InGaAs/n-InP interfaces

The low-pressure MOVPE-grown p-InGaAs-on-n-InP and n-InP-on-p-InGaAs diodes were characterized by I–V and C–V measurements to study the effects of the growth conditions on the heterointerface. The obtained band discontinuity in the conduction band ΔE_c ranged from 0.19 to 0.32 eV. It was found that ΔE_c was very sensitive to the growth interruption at the InP/InGaAs heterointerface. The n-InP-on-p-InGaAs diodes tend to show higher ΔE_c than the p-InGaAs-on-n-InP diodes. The decreased ΔE_c at InGaAs-on-InP heterointerface might be attributed to the graded layer of InGaAsP formed by intermixing at the interface. It is concluded from the estimated ΔE_c that the InP-on-InGaAs heterointerface is more abrupt than the InGaAs-on-InP heterointerface. An improvement of the InGaAs-on-InP heterointerface is mandatory for fabrication of high-performance double heterojunction bipolar transistors with InP collector layers.     

Non-parametric kernel regression for multinomial data

This paper presents a kernel smoothing method for multinomial regression. A class of estimators of the regression functions is constructed by minimizing a localized power-divergence measure. These estimators include the bandwidth and a single parameter originating in the power-divergence measure as smoothing parameters. An asymptotic theory for the estimators is developed and the bias-adjusted estimators are obtained. A data-based algorithm for selecting the smoothing parameters is also proposed. Simulation results reveal that the proposed algorithm works efficiently.     

An explicit formula for Koecher-Maaß Dirichlet series for Eisenstein series of Klingen type

We give a reasonable expression of the Koecher-Maaß Dirichlet series for the Klingen-Eisenstein lift of an elliptic cusp form.     

An asymmetric synthesis of α-tocopherol side chain

A stereospecific synthesis of (3R,7R)?3,7,11-trimethyldodecanal (2) with highly optical purity was achieved by utilizing the coupling reaction of the amino sulfone (9) with(R)?3,7-dimethyloctyl magnesium bromide (7), and the asymmetric isomerization of the resulting(E)-allylic amine (10).     

Novel generation of selenoaldehydes through stannic chloride-induced unsymmetrical C-Se bond cleavage of bis(N,N-dimethylcarbamoylseleno)methanes

Treatment of a benzene or a CH₂Cl₂ solution of bis(N,N-dimethylcarbamoylseleno)methanes with SnCl₄ afforded β-1,3,5-triselenanes, and the key intermediates, acylselonium ions and selenoaldehydes, were successfully trapped by using allyltrimethylsilane or 2,3-dimethyl-1,3-butadiene to obtain the allylation products or the cycloadducts, respectively.     

Rhodium-catalyzed [2 + 2 + 2] cyclotrimerization in an aqueous-organic biphasic system

Macrocyclization via rhodium-catalyzed intramolecular [2 + 2 + 2] annulation of triynes has been explored in an aqueous-organic biphasic system. The biphasic system controls the concentration of hydrophobic substrates in the aqueous reaction phase and offers diluted reaction conditions without the use of a slow addition technique. The system also achieves selective cross-annulation between hydrophobic diynes and hydrophilic alkynes.     

Preparation of functionally Pegylated gold nanoparticles with narrow distribution through autoreduction of auric cation by alpha-biotinyl-PEG-block-[poly(2- (N,N-dimethylamino)ethyl methacrylate)

PEGylated gold nanoparticles with biotin moieties installed at the distal end of the PEG tethered chains were prepared by the autoreduction of HAuCl4 catalyzed by alpha-biotinyl-PEG-block-poly[2-(N,N-dimethylamino)ethyl methacrylate] (biotinyl-PEG/PAMA) in aqueous medium at room temperature. The size of the gold nanoparticles was controllable in a range of 6-13 nm by changing the initial Au3+/polymer ratio, while retaining their narrow size distribution. The dispersion stability of the nanoparticles in aqueous medium was extremely high even under the condition of salt concentration as high as I = 2.0. Biotinyl-PEG/PAMA-anchored gold nanoparticles underwent specific aggregation in the presence of streptavidin, revealing their promising utility as colloidal sensing systems applicable under biological condition.     

Titanium N-heterocyclic carbene complexes incorporating an imidazolium-linked bis(phenol)

The synthesis and characterization of titanium complexes of the aryloxido-functionalized N-heterocyclic carbene ligand (L) is reported, in which the tridentate L ligand meridionally coordinates to the metal center.     

Enantiospecific synthesis of an indolizidine alkaloid, (+)-ipalbidine

Enantiospecific total synthesis of an indolizidine alkaloid, ipalbidine, was achieved starting from (−)-pyroglutamic acid by employing an intramolecular McMurry coupling reaction with a low-valent titanium, as a key step.