A new tomato pregnane glycoside from the overripe fruits

A new pregnane glycoside has been isolated from the overripe fruits of Cherry tomato (Mini tomato), Lycopersicon esculentum var. cerasiforme (DUNAL) ALEF. The structure was determined to be 3-O-beta-lycotetraosyl 3beta-hydroxy-5alpha-pregn-16-en-20-one on the basis of spectroscopic analysis. The seasonal variation of the tomato saponin is discussed.     

Relation between the Landau-Migdal interaction and the separable interaction

The Landau-Migdal interaction has been used widely in analyses of the quenching of spinisospin transitions. The separable interaction, on the other hand, has been used for studies of electric giant resonances and low-lying vibrational states, and recently for those of spin-isospin polarizations. The relation between these two interactions in the spin-isospin channel is studied. Quantitative comparison of these interactions in the spin-isospin L = 1 channel shows good correspondence between the nuclear matrix elements of the two types of interactions.     

Asymptotic analysis for an extended discrete Lotka–Volterra system related to matrix eigenvalues

The integrable discrete hungry Lotka–Volterra (dhLV) system is easily transformed to the qd-type dhLV system, which resembles the recursion formula of the qd algorithm for computing matrix eigenvalues. Some of the qd-type dhLV variables play a role for assisting the time evolution of the others. This property does not appear in the original dhLV system. In this article, we first show the existence of a centre manifold for the qd-type dhLV system. With the help of the centre manifold theory, we next investigate the local convergence of the qd-type dhLV system, and then clarify the monotonicity related to the qd-type dhLV variables at the final phase of the convergence.     

Variational Calculation of 4He Tetramer Ground and Excited States Using Realistic 4He–4He Potentials

We calculated binding energies and wave functions of the ⁴He tetramer ground and excited states employing various realistic ⁴He?⁴He potentials which includes the currently most accurate one with the adiabatic, relativistic, QED and residual retardation corrections. We used our Gaussian expansion method (GEM) for ab initio variational calculations of few-body systems. We found that precisely the same shape of the short-range correlation (r _ij < 4Å) in the dimer appear in the ground and excited states of trimer and tetramer. The four kinds of the binding energies of the trimer and tetramer ground and excited states, ${B_3^{(0)}, B_3^{(1)}, B_4^{(0)}}$ and ${B_4^{(1)}}$ , for the different potentials exhibit perfect linear correlations over the range of binding energies relevant for ⁴He atoms; namely, six types of the generalized atomic Tjon lines were observed.     

Odd-even effect and metal induced structural convergence in self-assembled monolayers of bipyridine derivatives

Scanning tunneling microscopy (STM) observations reveal that bipyridine derivatives which exhibit various two-dimensional structures due to the odd-even chain length effect are converged into a lamellar structure upon metal coordination.     

Electrostatic Retention Mechanism of 2,2'-Dihydroxyazobenzene-Metal chelates on Octadecylsilanized Silica Stationary Phase

The chelating agent 2,2'-dihydroxyazobenzene (DHAB), as shown in Fig. 1, was superior to the determination of trace metal ions by HPLC with ion-pair partition mode. Among the DHAB-metal chelates, only the cationic DHAB-aluminium 1:lchelate,[AIL]⁺, is fluorescent. Thus this chelate is expected to be applicable for selective and sensitive determination of aluminium ion by HPLC. However, the retention behavior of[AlL]⁺ on octadecylsilanized silica stationary phase was not well understood. The interaction between[A1L]⁺ and octadecylsilanized silica stationary phase has been investigated.     

Polycondensations of dicarboxylic acids and diols derived from optically active amino alcohols

Polycondensations of dicarboxylic acids with diols having amide moieties derived from optically active amino alcohols were carried out. Polymers with M _ns 8,700–17,400 were obtained by the polycondensations using 1.2 eq. of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC·HCl) in DMF at room temperature for 8 h in satisfactory yields. The T_g of the polymer rose with decrease of the methylene chain length of the dicarboxylic acid. In the T_gs of the polymers from L-leucinol, even-odd effect was observed with increase of the methylene chain length of the dicarboxylic acid. The molecular rotation values of the polymers were constant except for the polymer from succinic acid, which showed the negatively largest one. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2925–2934, 1997     

Ion-pair adsorption film colorimetry — A new simple method for ppb level of aluminum ion in water sample

A new, highly sensitive and simple colorimetric method for trace aluminum(III) with 2,2-dihydroxyazobenzene, H₂L, is described, based on the ion-pair adsorption of the anionic Al chelate, [A1L₂ ^–, with crystal violet cation, CV⁺, on the surface of Polyvinylchloride film plasticized with dioctylphthalate. The blue violet species, CV⁺[A1L₂]^–, is enriched onto the transparent film, leading to a remarkable enhancement of the sensitivity, and the detection limits are 3 ng/ml by spectrophotometry and 5 ng/ml by visual colorimetry, respectively. Using spectrophotometer, a linear calibration curve is obtained over the concentration range of 0 to 50 ng/ml of Al. Further, the color system, consisting of red ([A1L₂]^–), yellow (H₂L), and blue violet (CV⁺), gave clear color changes suitable for visual determination of aluminum with an applicable range of 0 to above 3000 ng/ml. The four different color zones are khaki for 0–5 ng/ml, reddish-brown for 5–200 ng/ml, blue violet for 200 ng/ml-3g/ml, and colorless for more than 3g/ml. The proposed method has been successfully applied for the determination of aluminum in tap waters.     

LC–UV Methodology for Simultaneous Determination of Lamivudine and Zidovudine in Plasma by Liquid–Liquid Extraction

This study describes an accurate, sensitive, and specific chromatographic method for the simultaneous quantitative determination of lamivudine and zidovudine in human blood plasma, using stavudine as an internal standard. The chromatographic separation was performed using a C8 column (150 × 4.6 mm, 5 μm), and ultraviolet absorbency detection at 270 nm with gradient elution. Two mobile phases were used. Phase A contained 10 mM potassium phosphate and 3% acetonitrile, whereas Phase B contained methanol. A linear gradient was used with a variability of A-B phase proportion from 98–2% to 72–28%, respectively. The drug extraction was performed with two 4 mL aliquots of ethyl acetate.     

An enzyme-encapsulated microreactor for efficient theanine synthesis

A flow-type microreactor containing glutaminase-mesoporous silica composites with 10.6 nm pore diameter (TMPS10.6) was developed for the continuous synthesis of theanine, a unique amino acid. High enzymatic activity was exhibited by the local control of the reaction temperature.