Cytotoxic Components from the Leaves of Schefflera Taiwaniana

The isolation and identification of eighteen components from the leaves of Schefflera taiwaniana are presented. Their structures were determined on the basis of spectral data as well as direct comparison with authentic samples. These compounds include two polyacetylenes, one carotenoid‐like, three sesquiterpenes, one diterpene, four triterpenes, two tocopherols, and five alkyl 4‐hydroxycinnamate mixtures. Among these, 4‐hydroxy‐trans‐cinnamic acid docosyl ester and 4‐hydroxy‐cis‐cinnamic acid tetracosyl ester are new compounds. Some of these components exhibit cytotoxic activity.     

Response of bilateral breasts to the endogenous hormonal fluctuation in a menstrual cycle evaluated using 3D MRI

The normal breast tissue responds to the fluctuation of endogenous hormones during a menstrual cycle (MC) and shows changes in breast density. The changes between left and right breasts of the same women were compared to evaluate the symmetrical response. Twenty-four healthy women were recruited in this study. Four weekly magnetic resonance imaging (MRI) studies were performed during one MC. A computer algorithm was used to segment the breast and the fibroglandular tissue to measure the fibroglandular tissue volume (FV) and three morphological parameters: circularity, convexity and irregularity. The coefficient of variation (CV) for each parameter measured among four MRI studies was calculated; also, the maximal percent change between two MRI studies that show the highest and the lowest FV was calculated. These parameters measured from left and right breasts were compared using Pearson correlation.     

Crystal Structure of Lanthanide‐oxalate‐pyridine‐2,4‐dicarboxylate Coordination Polymers Suggesting the Reductive Coupling of Carbon Dioxide to Oxalate

Under the hydrothermal conditions, Nd(NO₃)₃·6H₂O reacted with pyridine‐2,4‐dicarboxylic acid (2,4‐pydcH₂) to give a 2D co‐ordination polymer with the empirical formula of C₁₆H₁₈N₂Nd₂O₁₈×H₂O ( 1 ). Pr(NO₃)₃·6H₂O also reacted with 2,4‐pydcH₂ to give another 2D coordination polymer (C₈H₉NO₉Pr)₂·H₂O ( 2 ). The structure of both polymers have been determined by X‐ray diffraction. X‐ray structural analyses show that both polymers contain bridging oxalate (C₂O₄^2?) ligands, which might have been formed by the coupling of two CO₂^?× radicals, released from pydc^2? ligands.     

Practice makes perfect on the blackboard: A cultural analysis of mathematics instructional patterns in Taiwan

Studies show a sharp difference in math achievement between students in the U.S. and students in several East Asian countries, amongst them Taiwan. It is suggested that the patterns of math instruction applied by teachers may have contributed to these differences. This study intends to investigate the patterns of math instruction applied by the Taiwanese teachers and to delve into the cultural roots of these patterns. Data source includes videotaping of instruction by three middle school math teachers and a questionnaire survey of 297 eighth-graders. It was found that the Taiwanese math instruction pattern may be summarized as a cultural activity of “practice makes perfect, on the blackboard”. The underlying cultural beliefs are further explored, including the incremental view of human intelligence, self-improvement through diligent effort, and the teacher's role as an authority figure.     

Bioactive Components from the Mycelium of Antrodia Salmonea

Three new compounds, 2,4‐dimethoxy‐6‐methylbenzene‐1,3‐diol ( 1 ), salmoquinone ( 2 ), and 3‐(4‐hydroxyphenyl)‐4‐isobutyl‐1H‐pyrrole‐2,5‐dione ( 3 ), together with six known compounds, 2‐methoxy‐6‐methyl‐p‐benzoquinone ( 4 ), 2,3‐dimethoxy‐5‐methyl‐p‐benzoquinone ( 5 ), 2‐hydroxy‐5‐methoxy‐3‐methyl‐p‐benzoquinone ( 6 ), eburcoic acid ( 7 ), fomefficinic acid C ( 8 ), and a pyrroledione ( 9 ), were isolated from the mycelium of Antrodia salmonea. The structures of these compounds were elucidated by spectrometric analyses including IR, NMR, and MS. Among these compounds, 4 and 5 exhibited cytotoxicity against KB, HepG2, and H2058 cell lines.     

Synthesis of β-Disubstituted Enones from Ynones. An Alternative Route to 1,4-Addition of Cuprate to the Ynone System

A one-pot reaction of 4-phenyl-3-butyn-2-one with hydrogen iodide generated in situ gave a hydroiodinated product that underwent cross coupling with organozinc compounds in the presence of palladium catalyst to provide a simple preparation of 4-disubstituted-3-alken-2-ones in fair to good yields.     

Characterization of ring‐opening polymerization of genipin and pH‐dependent cross‐linking reactions between chitosan and genipin

In this study, a novel chitosan‐based polymeric network was synthesized by crosslinking with a naturally occurring crosslinking agent—genipin. The results showed that the crosslinking reactions were pH‐dependent. Under basic conditions, genipin underwent a ring‐opening polymerization prior to crosslinking with chitosan. The crosslink bridges consisted of polymerized genipin macromers or oligomers (7 ～ 88 monomer units). This ring‐opening polymerization of genipin was initiated by extracting proton from the hydroxyl groups at C‐1 of deoxyloganin aglycone, followed by opening the dihydropyran ring to conduct an aldol condensation. At neutral and acidic conditions, genipin reacted with primary amino groups on chitosan to form heterocyclic amines. The heterocyclic amines were further associated to form crosslinked networks with short chains of dimmer, trimer, and tetramer bridges. An accompanied reaction of nucleophilic substitution of the ester group on genipin by the primary amine group on chitosan would occur in the presence of an acid catalysis. The extent in which chitosan gels crosslinked with genipin was significantly dependent on the crosslinking pH values: 39.9 ± 3.8% at pH 5.0, 96.0 ± 1.9% at pH 7.4, 45.4 ± 1.8% at pH 9.0, and 1.4 ± 1.0% at pH 13.6 (n = 5, p < 0.05). Owing to the different crosslinking extents and different chain lengths of crosslink bridges, the genipin‐crosslinked chitosan gels showed significant difference in their swelling capability and their resistance against enzymatic hydrolysis, depending on the pH conditions for crosslinking. These results indicated a direct relationship between the mode of crosslinking reaction, and the swelling and enzymatic hydrolysis properties of the genipin‐crosslinked chitosan gels. The ring‐opening polymerization of genipin and the pH‐dependent crosslinking reactions may provide a novel way for the preparation and exploitation of chitosan‐based gels for biomedical applications. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1985–2000, 2005     

Monotone variations of the first eigenvalue for doubly connected domains

The first Dirichlet eigenvalue for the Laplace operator of a doubly connected plane domain varies with the relative position of the inner hole. Under certain mild hypothesis it decreases as the two boundary curves get closer along some specific direction. We made this observation by analyzing level curves and rearrangement technique.     

Lignans and anthraquinones from the fruits of Morinda citrifolia

Two new anthraquinones, 1,6-dihydroxy-5-methoxy-2-methoxymethylanthraquinone (1) and 1,5,7-trihydroxy-6-methoxy-2-methoxymethylanthraquinone (2), and one new lignan isoamericanoic acid A (3) were isolated from the fruits of Morinda citrifolia along with 11 known compounds scopoletin, luteolin, americanin A, americanin D, 3,3'-bisdemethylpinoresinol, p-cresol, p-hydroxybenzoic acid, p-hydroxybenzaldehyde, 4-hydroxy-3-methoxybenzaldehyde, 4-hydroxy-3-methoxycinnamaldehyde, and 2,5-dihydroxy-4-methoxybenzaldehyde. The structures of all compounds were elucidated by spectroscopic analysis.