Formosadimers A, B, and C from the Bark of Calocedrus macrolepis var. formosana

Formosadimers A, B, and C, together with one known compound, sugikurojin B, have been isolated from the bark of Calocedrus macrolepis var. formosana. Formosadimers A, B, and C, and sugikurojin B are dimers of the abietane-O-abietane type. Their structures were elucidated principally based on spectroscopic data.     

Blind phase retrieval and source separation of electromagnetic fields

Blind source separation of two electromagnetic fields is investigated. The difficulty of this task lies in the fact that only the power, which is the square of the sum of the electromagnetic fields, can be directly measured; the cross term of the electromagnetic fields is inevitable, and a strong correlation occurs in blind deconvolution. However, the relative phase is physically different from the field intensities, and, hence, extracting the phase during separation seems inconceivable. Our results demonstrate that the intensities and the relative phase of two electromagnetic waves can be determined with eigenvalue problem formalism even when the mixing processes are completely unknown.     

Convergence rate analysis of an asynchronous space decomposition method for convex minimization

We analyze the convergence rate of an asynchronous space decomposition method for constrained convex minimization in a reflexive Banach space. This method includes as special cases parallel domain decomposition methods and multigrid methods for solving elliptic partial differential equations. In particular, the method generalizes the additive Schwarz domain decomposition methods to allow for asynchronous updates. It also generalizes the BPX multigrid method to allow for use as solvers instead of as preconditioners, possibly with asynchronous updates, and is applicable to nonlinear problems. Applications to an overlapping domain decomposition for obstacle problems are also studied. The method of this work is also closely related to relaxation methods for nonlinear network flow. Accordingly, we specialize our convergence rate results to the above methods. The asynchronous method is implementable in a multiprocessor system, allowing for communication and computation delays among the processors.

     

Long range 31P?1H couplings in phosphorylated iminothiazolines and iminooxazolines

Long range ³¹P? ¹H coupling constants of 21 phosphorylated iminothiazolines and two phosphorylated iminooxazolines have been studied. The size of the ³¹P? ¹H coupling in the H? C? N? C?N? P framework is larger than that in the H? C? S? C?N? P framework which is in turn larger than the H? C? O? C?N? P framework. The value of the ³¹P? ¹H coupling through the H? C? N? C?N? P framework decreases in the order of P > PS > PO, whereas a reverse trend is observed for the H? C? S? C?N? P framework. A planar zig-zag configuration has been proposed for the long range ³¹P? ¹H couplings.     

Capillary electrophoresis using immobilized whole cells with overexpressed endothelin receptor for specific ligand screening

A new capillary electrophoresis method using immobilized cells as the stationary phase has been developed. The power of this method is demonstrated by the separation and identification of endothelin antagonists on a capillary column coated by the transfected Chinese hamster ovary (CHO) cells with overexpressing endothelin receptors. The screening results are validated by functional assays suppressing the increase of intracellular calcium concentration induced by endothelin-1. Instead of making efforts in isolating protein receptors, the easily prepared whole-cell capillary column provides a superior tool on the basis of ligand/receptor affinity for a rapid screening of potent drug candidates from compound libraries.     

Double-quantum NMR spectroscopy based on finite pulse RFDR

We demonstrate that the finite pulse RFDR sequence (J. Chem. Phys. 114 (2001) 8473) can be used effectively for ³¹P double-quantum NMR spectroscopy at a spinning frequency of 10 kHz. The ³¹P NMR data measured for hydroxyapatite and octacalcium phosphate show that sizable double-quantum excitation efficiency can be obtained with the ratio of the recoupling field to spinning frequency set equal to 1.67.     

A note on activity floats in activity-on-arrow networks

In project scheduling, the free float (slack) of an activity represents the leeway for scheduling the activity without affecting any subsequent activity. In the context of activity-on-arrow (AOA) network representation, textbooks on project management, based on our survey, have for decades been using a popular formula to calculate free floats that may lead to erroneous results in the presence of dummy arcs. In this note, we present a correct version of the formula. Extensions of the proposed formula to other floats such as safety float and interference float are also discussed.     

悖论与数学基础问题(Ⅱ)

在本文中,主要讨论悖论定义问题,此外,还将对‘悖论的起源’、‘数学三次危机’和‘Zermelo解决悖论的方案’等内容作简要的综述和评论。至于Russell对悖论的解决方案与悖论成因等内容的讨论将在本文的续篇中给出。     

Uniform polymer particles by dispersion polymerization in alcohol

Uniform polystyrene particles in 1–10 μm size range and up to 40% solid contents have been prepared by polymerizing styrene in ethyl alcohol with azo-type initiators and a polymeric stabilizer polyvinylpyrrolidone along with an anionic, nonionic, or comonomeric co-stabilizer. Effects of polymerization parameters, such as monomer concentration, type of co-stabilizer, initiator type and concentration, crosslinking monomer, and diluent on average particle size and size distribution have been studied. Functional groups such as hydroxyl, carboxyl, amine, amide, silane, polydimethylsiloxane, and silacrown have been successfully incorporated onto the particles by copolymerization. A mechanism for particle formation and growth in dispersion polymerization is presented.