[reaction: see text] A new method for preparation of 3(I)-O-substituted beta-cyclodextrin derivatives was developed. Cinnamyl bromide reacts with beta-cyclodextrin to form predominantly the 3(I)-O-cinnamyl derivative (30% isolated yield, >90% regioselectivity). After protection of the remaining cyclodextrin hydroxyls by acetylation, the cinnamyl group can be easily transformed to many other groups (exemplified by transformation to 3(I)-O-carboxymethyl derivative). Substitution pattern in singly modified CDs was unambiguously determined by a combination of 2D NMR techniques. 相似文献
High-spin states in the 97Tc nucleus have been studied by in-beam γ-ray spectroscopy with the reaction 82Se(19F,4nγ) at 68 MeV incident energy. Excited states have been observed up to about 8 MeV excitation and spin 43/2. The observed
level scheme is compared with results of shell model calculations.
Received: 22 November 2002 / Accepted: 23 December 2002 / Published online: 18 March 2003
RID="a"
ID="a"e-mail: bucurescu@tandem.nipne.ro
RID="b"
ID="b"Present address: INFN, Laboratori Nazionali di Legnaro, Legnaro, Italy.
RID="b"
ID="b"Present address: INFN, Laboratori Nazionali di Legnaro, Legnaro, Italy.
RID="b"
ID="b"Present address: INFN, Laboratori Nazionali di Legnaro, Legnaro, Italy.
RID="c"
ID="c"Present address: Università di Padova, Padova, Italy.
Communicated by C. Signorini 相似文献
Mean lives and excitation energies of the lowest levels in64Ni,66Zn and68Zn were measured with the aid of the (α, α′γ) and (α, pγ) reactions. The γ-rays were detected in coincidence with the outgoing particles. The following mean lives were determined from DSA measurements: 400 ± 150 fs for the level at Ex = 1.35 MeV in 64Ni; 270 ± 100, 210 ± 110, 330 ± 200, 80 ± 70 fs for the levels at Ex = 1.87, 2.45, 2.83, 2.94 MeV in 66Zn, and 1300 ± 300, > 160, 600 ± 200 fs for the levels at Ex = 1.08, 1.89 and 2.76 MeV in 68Zn, respectively. 相似文献
The arginase enzyme was bound to porous silica using a reactive polymer where two types of nanomaterials were entrapped, i.e., carbon nanotubes (CNTs) and boron nitride nanotubes (BNNTs). For the first time, it was shown that BNNTs were highly efficient for increasing the performance of a particulate bioactive support. Also, we demonstrated that BNNTs enhanced more strongly this effect in comparison with CNTs. In addition, with this novel bioactive support, the relative IC50 values of the well-known arginase inhibitors were found to be in agreement with those derived by the conventional spectrometric method. It was shown the ethylacetate extract of the roots of Spirotropis longifolia (SL) and of the ethanol extract of sunflower (Helianthus annuus) seed (SS) and Lonicera japonica Thunb, i.e., honeysuckle (H) on the arginase activity inhibited the enzyme activity.
We developed a new type of three-layered skin tissue phantom using silicone material. This phantom maintains its optical properties in a certain period of time, typically about three months, which is much longer than about 30 min with our previous agar-type phantom. Experiments on spectral reflectance measurements and color analysis indicate the possibility of silicone-type skin tissue phantom. 相似文献
Eight hydrochlorides of 3-{2-[(2/4-fluorophenoxy)-ethylamino]}-2-hydroxypropyl-4-alkoxybenzoates and four hydrochlorides of 3-tert-butylamino-2-hydroxypropyl-4-butoxybenzoates were prepared as potential antagonists of the β1-adrenergic receptor (beta-blockers). A multistep synthesis of these compounds is described as well as their detailed analytical characterization. The pharmacokinetic properties of these weak base compounds are significantly influenced by their acid-base dissociation constant, pKa. The knowledge of this value is crucial for new drug development. This paper is aimed at developing a methodology that utilizes pH-dependent 1H NMR spectroscopy for its routine analysis. The selected predicted physico-chemical parameters of the new (arylcarbonyloxy)aminopropanols (i.e., aryloxyaminopropanol derivatives) were compared with the model drugs esmolol and flestolol. 相似文献
Doxorubicin (DOX) belongs to the group of anthracycline antibiotics with very effective anticancer properties. On the other hand, the cardiotoxic effects limit its application over the maximum cumulative dose. To overcome this obstacle, encapsulation of this drug into the protective nanotransporter such as apoferritin is beneficial. In this study, fluorescent behavior of DOX in various solvents was determined by fluorescence spectrometry, demonstrating the fluorescence quenching effect of water, which is often used as a solvent. It was found that by increasing the amount of the organic phase in the DOX solvent the dynamic quenching is significantly suppressed. Ethanol, acetonitrile and dimethyl sulfoxide were tested and the best linearity of the calibration curve was obtained when above 50 % of the solvent was present in the binary mixture with water. Moreover, pH influence on the DOX fluorescence was also observed within the range of 4–10. Two times higher fluorescence intensity was observed at pH 4 compared to pH 10. Further, the DOX behavior in capillary electrophoresis (CE) was investigated. Electrophoretic mobilities (CE) in various pH of the background electrolyte were determined within the range from 16.3 to −13.3 × 10 −9 m−2 V−1 s−1. Finally, CE was also used to monitor the encapsulation of DOX into the cavity of apoferritin as well as the pH-triggered release.