A Nifedipine Coground Mixture with Sodium Deoxycholate. I. Colloidal Particle Formation and Solid-State Analysis

Sodium deoxycholate (DCNa) is a bile salt that forms multimolecular inclusion compounds with a variety of organic substances. In this study, complex formulation of DCNa with nifedipine, a poorly water soluble drug, by grinding was investigated. The coground mixture was prepared with a vibration rod mill, and its solid state was characterized using powder X-ray diffraction, differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy. A laser diffraction particle size analyzer was also used to determine the particle size distribution curve in solution. When a nifedipine-DCNa (1:2 w/w) mixture coground for 30 min was dispersed into water and a pH 6.8 buffer solution, a semitransparent colloidal solution occurred immediately; 90% of the total particles formed in solution had a diameter less than 600 nm. Both powder X-ray diffraction peaks and DSC endothermic peak of nifedipine crystals were not found for the coground mixture, whereas a new exothermic peak was observed on DSC thermograms. The magnitude of this exothermic peak depended on the weight fraction of DCNa and the grinding time, indicating that nifedipine crystals changed into an amorphous state by complex formation with DCNa during the grinding process. In the FTIR spectrum of the coground mixture, the peaks of aromatic CH out-of-plane bend and dihydropyridine NH stretch of nifedipine were considerably weakened, suggesting that van der Waals interaction may be present between the drug and DCNa molecules. From these results, it is clear that the cogrinding method with DCNa is very useful for the formation of amorphous nifedipine in the solid state and the production of colloidal particles of the drug in solution.     

Realization of a triple-tail cell with high input resistance for low-voltage application

An operational transconductance amplifier (OTA) is a useful function block for analogue signal processing. A triple-tail cell possesses a wider linear input voltage range than an emitter-coupled pair, in spite of its simple configuration. In practical implementation of the triple-tail cell, the maintenance of the intrinsic linearity necessitates a voltage divider which has low resistance. This lowers the input resistance of the triple-tail cell. This paper describes a method of realizing high input resistance of the triple-tail cell. An active voltage divider composed of two OTAs is connected to the triple-tail cell. The linearity of the triple-tail cell with the divider deteriorates little. The whole circuit can operate at a low supply voltage. Although an emitter-coupled pair is employed as the OTA in the active divider, the linearity of the divider is good. Simulation results of an OTA-C filter that consists of the triple-tail cell and capacitors show that satisfactory characteristics are obtained.     

Striking effects of cobalt (III) nuclearity in fused salphen complexes on their electroconductivity and thin film transistor activity

Dinuclear and trinuclear cobalt (III) complexes were prepared using fused salphen ligands that have the same number of benzene rings along the major axis of the molecules. The two compounds were used as organic thin film formed on a glass or a SiO₂/n-Si substrate for investigating electronic conductivity and transistor characteristics, respectively. The conductivity of di- and trinuclear complexes were 8.5 × 10⁻⁵ and 5.8 × 10⁻³ S cm⁻¹, meaning that the increment of the nuclearity from two to three resulted in multiplication of 70 times. The thin film of the trinuclear complex showed a faint transistor activity, where the thin film act as n-type semiconductor. In contrast, the dinuclear complex did not afford a detectable response to the gate voltage.     

A novel trans-4-hydroxycinnamic acid derivative from Meyer lemon (Citrus meyeri)

Isolation and structural elucidation of a new trans-4-hydroxycinnamic acid derivative from Meyer lemon (Citrus meyeri hort. ex Y. Tanaka) was carried out. The derivative exhibited the antioxidative activity by ORAC (oxygen radical absorbance capacity) assay and was found in the flavedo and alvedo of Meyer lemon peel.     

Asian American psychology meets the twenty-first century.

Reviews the book, Asian American psychology: Current perspectives edited by Nita Tewari and Alvin Alvarez (2007). Drs. Nita Tewari and Alvin Alvarez have compiled and edited a well-organized, comprehensive, user-friendly textbook on Asian American psychology. The 58 contributing authors represent the breadth and diversity of this growing field of study. The reader who is looking for simple answers about Asian America will be frustrated by the book, as the complex texture and nuance within “Asian America” is well represented. The 650-page volume is divided into six sections: Foundations and Roots, Balancing Multiple Worlds, Gender and Intimate Relationships, Next Generation, Social and Life Issues, and Health and Well-Being. The book is oriented toward the subfields of personality, counseling, and clinical psychology. Readers will have to look beyond this text to learn about the contributions of our colleagues in social psychology. This text is suitable for undergraduates and beginning graduate students. It contains a goldmine of information that faculty can use very flexibly. Faculty and instructors teaching classes such as Asian American Psychology, Cross-Cultural Psychology, or Asian American Families will be able to use this book as a primary text. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inhibitory Effects of Pomegranate Extracts on Recombinant Human Maltase–Glucoamylase

α‐Glucosidase inhibitors are currently used in the treatment of type 2 diabetes. In this study, we investigated the inhibitory activities of aril and pericarp extracts from pomegranates obtained various regions against recombinant human maltase–glucoamylase (MGAM). The inhibitory activities of the aril extracts tended to be stronger than those of the pericarp extracts. The Iranian aril extract was the most effective inhibitor. We investigated the polyphenol content of the pomegranate extracts using the Folin–Ciocalteu method. Among the aril extracts, the Iranian aril extract showed the highest polyphenol content. We further evaluated inhibitory activity against α‐glucosidase from the rat small intestine. Pomegranate extract used in this study showed slightly different inhibitory activities according to α‐glucosidase origin. Iranian aril extract was the most effective inhibitor of α‐glucosidases, especially recombinant human MGAM. Bioassay‐guided fractionation of the pomegranate arils led to identification of punicalagin and oenothein B as potent inhibitors of α‐glucosidase. Oenothein B showed inhibitory activity with a half‐maximal inhibitory concentration (IC₅₀) value of 174 μM. Its potency was comparable to that of the α‐glucosidase inhibitor acarbose with an IC₅₀ value of 170 μM. Dixon plot kinetic analysis of oenothein B showed a noncompetitive inhibition with a K_i value of 102 μM. These results suggest that pomegranate arils would be useful for suppressing postprandial hyperglycemia.     

Carbon-nanotube-based triode-field-emission displays using gatedemitter structure

We fabricated a carbon-nanotube-based triode-field-emission display with a gated emitter structure made up of a gate layer, a thin insulating layer, and a carbon nanotube layer. A low threshold voltage of 20 V and a total anode current of 0.5 mA at 80 V were observed for 30×30 pixel panels. We also demonstrated highly efficient and homogeneous emission from all pixels at voltages lower than 100 V. Based on simulation of electric fields in gate holes, further improvement of the emission properties is expected by optimizing its structural parameters, such as the gate-hole diameter