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271.
A previous study on spray-drying demonstrated that it could promote the solubility of poorly water-soluble drugs using water-soluble polymers. Here, the preparation of composite particles of salbutamol sulfate (Sb) with water-insoluble polymers, such as Eudragit RS (RS) or Eudragit RL (RL) as a carrier, was examined. Despite the water insolubility of both polymers, the permeability of water was low in the former but high in the latter. We attempted to prepare controlled release composite particles by exploiting the characteristics of these carriers. The composite particles of the three components (Sb, RS, and RL) were prepared using a 4-fluid nozzle spray-dryer, and their physico-chemical and dissolution properties were compared with physical mixtures. Examination of particle morphology by scanning electron microscopy (SEM) revealed that the particles from the spray-drying process had atomized to several microns and were spherical. Analysis by X-ray diffraction and differential scanning calorimetry revealed that diffraction peaks and heat of fusion of Sb in the spray-dried samples decreased, indicating that the drug was amorphous and formed a solid dispersion. FT-IR analysis suggested that the amino group of Sb and a carbonyl group of the polymers formed a hydrogen bond. A dissolution test of Sb-RS-RL particles prepared using the 4-fluid nozzle spray-drying method showed that release rates were depressed significantly compared to the physical mixture at pH 1.2 and 6.8, and the depression was greater when RS was used instead of RL, presumably because of the permeability difference. The compression of these particles into tablets revealed that desirable controlled released dosage forms could be prepared. In addition, Sb was used to simulate an anti-asthmatic drug. For this an Andersen cascade impactor for dry powder inhalers was used to investigate delivery to the lungs. 相似文献
272.
Dr. Junhao Wang Jakub J. Zakrzewski Mikolaj Zychowicz Yue Xin Prof. Hiroko Tokoro Dr. Szymon Chorazy Prof. Shin-ichi Ohkoshi 《Angewandte Chemie (International ed. in English)》2023,62(35):e202306372
A conjunction of Single-Molecule Magnet (SMM) behavior and luminescence thermometry is an emerging research line aiming at contactless read-out of temperature in future SMM-based devices. The shared working range between slow magnetic relaxation and the thermometric response is typically narrow or absent. We report TbIII-based emissive SMMs formed in a cyanido-bridged framework whose properties are governed by the reversible structural transformation from [TbIII(H2O)2][CoIII(CN)6] ⋅ 2.7H2O ( 1 ) to its dehydrated phase, TbIII[CoIII(CN)6] ( 2 ). The 8-coordinated complexes in 1 show the moderate SMM effect but it is enhanced for trigonal-prismatic TbIII complexes in 2 , showing the SMM features up to 42 K. They are governed by the combination of QTM, Raman, and Orbach relaxation with the energy barrier of 594(18) cm−1 (854(26) K), one of the highest among the TbIII-based molecular nanomagnets. Both systems exhibit emission related to the f–f electronic transitions, with the temperature variations resulting in the optical thermometry below 100 K. The dehydration leads to a wide temperature overlap between the SMM behavior and thermometry, from 6 K to 42 K. These functionalities are further enriched after the magnetic dilution. The role of post-synthetic formation of high-symmetry TbIII complexes in achieving the SMM effect and hot-bands-based optical thermometry is discussed. 相似文献
273.
Synthesis of Silaphenalenes by Ruthenium‐Catalyzed Annulation between 1‐Naphthylsilanes and Internal Alkynes through CH Bond Cleavage
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Dr. Yuichiro Tokoro Kengo Sugita Prof. Dr. Shin‐ichi Fukuzawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(38):13229-13232
Ruthenium‐catalyzed annulation of 1‐naphthylsilanes with internal alkynes afforded silaphenalenes through cleavage of the C?H bond at the 8‐position of the naphthalene. [RuH2(CO){P(p‐FC6H4)3}3] efficiently catalyzed the reaction. The use of 1‐naphthyldiphenylsilane as a substrate resulted in a better yield of the annulation product compared to the use of silanes with alkyl groups on the silicon atom. Internal alkynes with both aryl and alkyl groups were tolerated in this reaction. 相似文献
274.
Watanabe Kazumi 《International Journal of Solids and Structures》1977,13(1):75-78
In this paper the transient behaviour of a contact shear stress in a layered elastic quarter space subjected to anti-plane shear loads is investigated. The loads are suddenly applied to upper and side edges of the layer. The effects of the reflected waves, the loaded position and the material properties to the contact shear stress are shown graphically. 相似文献
275.
Eiji Fujimori Tatsuya Hayashi Kazumi Inagaki H. Haraguchi 《Fresenius' Journal of Analytical Chemistry》1999,363(3):277-282
An analytical method for the determination of lanthanide elements in the bovine whole blood reference material (IAEA A-13)
has been investigated by inductively coupled plasma mass spectrometry (ICP-MS). The bovine whole blood reference material
was digested with HNO3 and HClO4, and then the pH of the digested solution was adjusted to 12 with 3 M sodium hydroxide aqueous solution. In this experimental
procedure, lanthanide elements in the blood sample were coprecipitated with iron mainly derived from heme-iron in blood itself.
In order to minimize matrix effects due to iron, excess iron in the analysis solution was removed by solvent extraction using
methyl isobutyl ketone (MIBK) prior to the determination of lanthanide elements by ICP-MS. The recoveries of all lanthanide
elements were almost quantitative in the recovery test. In consequence, it has been found that all lanthanide elements in
bovine whole blood reference material are at the wide concentration range of 0.90 pg/g for Tm ∼1880 pg/g for Ce.
Received: 2 May 1998 / Revised: 27 July 1998 / Accepted: 30 July 1998 相似文献
276.
Eiji Fujimori Tatsuya Hayashi Kazumi Inagaki H. Haraguchi 《Analytical and bioanalytical chemistry》1999,363(3):277-282
An analytical method for the determination of lanthanide elements in the bovine whole blood reference material (IAEA A-13)
has been investigated by inductively coupled plasma mass spectrometry (ICP-MS). The bovine whole blood reference material
was digested with HNO3 and HClO4, and then the pH of the digested solution was adjusted to 12 with 3 M sodium hydroxide aqueous solution. In this experimental
procedure, lanthanide elements in the blood sample were coprecipitated with iron mainly derived from heme-iron in blood itself.
In order to minimize matrix effects due to iron, excess iron in the analysis solution was removed by solvent extraction using
methyl isobutyl ketone (MIBK) prior to the determination of lanthanide elements by ICP-MS. The recoveries of all lanthanide
elements were almost quantitative in the recovery test. In consequence, it has been found that all lanthanide elements in
bovine whole blood reference material are at the wide concentration range of 0.90 pg/g for Tm ∼1880 pg/g for Ce.
Received: 2 May 1998 / Revised: 27 July 1998 / Accepted: 30 July 1998 相似文献
277.
Mamoru Nomura Xiang Liu Fumihiko Mizutani Syuzaemon Sato Kazumi Fujita 《Macromolecular Symposia》1995,92(1):233-242
Effects of various operating variables on the kinetic behavior of the seeded emulsion copolymerization of styrene and acrylonitrile and on the monomer concentration in the copolymer particles were examined. Applicability of high-performance liquid adsorption chromatography to determination of the average composition and composition distribution of the resulting copolymer was also examined. 相似文献
278.
Kei Kobayashi Hirofumi Yamada Toshihisa Horiuchi Kazumi Matsushige 《Applied Surface Science》1999,140(3-4):281-286
We demonstrated the high resolution imaging of the organic molecules using noncontact atomic force microscopy in ultrahigh vacuum. The sample was C60 molecules deposited on the Si(111)-7×7 reconstructed surface. When the thickness of the C60 film was submonolayer, we could image some isolated C60 molecules and the reconstructed Si surface simultaneously. However, the imaging was highly unstable not only because of the large structure but also due to the large difference between the interaction forces on the molecules and on the Si surface. On the other hand, when the thickness of the C60 molecules was almost monolayer, individual molecules could be stably imaged. 相似文献
279.
Diffusion is a spontaneous process and one of the physicochemical phenomena responsible for molecular transport, the rate of which is governed mainly by the diffusion coefficient; however, few coefficients are available because the measurement of diffusion rates is not straightforward. The translational diffusion coefficient is related by the Stokes–Einstein equation to the approximate radius of the diffusing molecule. Therefore, the stable conformations of small molecules were first calculated by molecular modeling. A simple radius rs and an effective radius re were then proposed and estimated using the stable conformers with the van der Waals radii of atoms. The diffusion coefficients were finally calculated with the Stokes–Einstein equation. The results showed that, for the molecules with strong hydration ability, the diffusion coefficients are best given by re and for other compounds, rs provided the best coefficients, with a reasonably small deviation of ~0.3 × 10−6 cm2/s from the experimental data. This demonstrates the effectiveness of the theoretical estimation approach, suggesting that diffusion coefficients have potential use as an additional molecular property in drug screening. 相似文献
280.