Evaluation of enteric coated tablet sensitive to pancreatic lipase. I. In vitro disintegration test.

We designed a new enteric coated preparation which is pH independent and functions by pancreatic lipase activity in the duodenum. Triolein (TO) and trilaurin (TL) were selected as lipase sensitive components and ethylcellulose (EC) was used as the support film for TO and TL. Tablets (330 mg, d = 10 mm) containing a model drug, sulfamethizole (SMZ), were coated with 1% each of TO, TL and EC solution by the fluidized bed coating technique. Disintegration tests were carried out in the media including JPXI 1st fluid (pH 1.2, JP-1), 2nd fluid (pH 6.8, JP-2) and JP-2 with gall powder and pancreatic lipase (JP-2-GL). The lag time of disintegration of the tablet (TOTL-Tab) coated 5-7 mg/tab with TO, TL and EC was about 10 min and all of the tablets disintegrated completely within 30 min in JP-2-GL. However, in the other media, which did not contain lipase, TOTL-Tab did not disintegrate for at least 2 h. It was confirmed that TO and TL in the coating film were digested by lipase. In addition, the tensil strength of the film decreased quickly after incubation in JP-2-GL. These results suggest that the application of TO, TL and EC to tablet coating is useful for an enteric release preparation sensitive to pancreatic lipase, even if patients have low gastric acidity or are taking antacids.     

Relation between the Fukui function and the Coulomb hole

By using a coarse-grain representation of the molecular electronic density, we demonstrate that the value of the condensed Fukui function at an atomic site is directly related to the polarization charge (Coulomb hole) induced by a test electron removed (or added) from (at) the atom. The link between the formation of an electron-hole pair and the condensed Fukui function provides insights on the possible negativity of the Fukui function which is interpreted in terms of two phenomena: overscreening and over-strengthening.     

Relation between aggregation kinetics and the structure of kaolinite aggregates

Dynamic and static light scattering were applied to the determination of the stability ratio and fractal dimension of kaolinite (KGa-2) at different kaolinite or/and electrolyte concentrations at pH 9.5. Dynamic light scattering was used to measure the kinetics of early stage aggregation to determine the stability ratio, W, as well as the cluster sizes which determine the fractal regime. Static light scattering was used to measure the fractal dimension, D(f). Results show that the two classes of "universality" (Lin et al. Nature 1989, 339, 360) characterizing the diffusion- and reaction-limited regimes of cluster-cluster aggregation do apply to colloidal kaolinite as limit cases when W approximately 1 or W > 100, respectively. In the intermediate regime where 5 < W < 100, the growth of the aggregate radius showed a power-law behavior similar to diffusion-limited cluster aggregation. For the intermediate aggregation regime, a scaling relation between fractal dimension and stability ratio, reflecting a continuous increase in particle packing density in the aggregate as the sticking probability of particles was reduced, was demonstrated.     

Correlations between structure and accelerated artificial ageing of XLPE

The elucidation of the structural and morphological changes that occur during the crosslinking of polyethylene and the correlation of these changes with the physical, chemical and ageing resistance is very important to forecast the properties and the performance of the final material.The accelerated ageing of XLPE samples with various degrees of crosslinking has been carried out using two types of artificial weathering equipments, with UV or Xenon light bulbs with different cycles of temperature and humidity, varying time of exposition for both systems. The changes in the properties of the materials have been analyzed by Tensile Tests, Scanning Electron Microscopy (SEM), Dynamic-Mechanical Analysis (DMA), X-Ray Diffraction (XRD). The main degradation effects for each level of crosslinking is presented for the pristine XLPE.     

Relation between the structure and extracting power of higher tertiary amines

The effect of the structure of some tertiary amines on the processes of the separation of cerium and neodymium nitrates by extraction has been examined. It was found that the changes in extracting power of these amines owing to their different structures can not be explained by only the inductive effects of the substituents on the nitrogen atom. The steric factors in extraction of rare earth elements (REE) by tertiary amines are of primary importance, the extraction mechanism of these elements vary with the change of the amine structure. It has been shown that the methyldialkylamines are the most effective extractants among the investigated amines for both the extraction and the separation of REE. This can be explained by the considerable reduction of the hydrocarbon part of the molecules of these extractants and by the consequent change of the extracting mechanism.     

Relation between the structure and extracting power of higher tertiary amines

The effect of the composition and structure of higher tertiary amines on their efficiency in extracting nitric acid has been examined. The ionization constants of the amines in methanol have been determined by potentiometric titration. The extraction constants for nitric acid have been determined at constant ionic strength in the aqueous phase (μ=1). The dependence of these constants upon the concentrations and the degree of association of the amine salts in the organic phase has been examined. For the cases in which the role of steric factors is negligible it has been shown that at low amine salt concentrations in the organic phase there are quantitative regularities between the ionization constants of the amines in methanol, their extraction constants for nitric acid and the inductive effects of the substituents on the nitrogen atom.     

交联聚乙烯醇膜材料中水的状态及其分离特性

以DCS分析了不同交联度的马来酸交联PVA模材料中结晶结合水的凝固点,及其交联度大小对高分子链与水分子间氢键强弱的影响,研究了不同交联度的PVA／PAN复合膜对乙醇一水的渗透汽化分离性能影响。结果表明,结晶结合水的凝固点越低,水分子与高分子链间的氢键作用越强;PVA／PAN复合膜的渗透通量随PVA交联度的增大而降低,分离系数则随交联度的增大而提高。     

Analysis of the equations for the temperature dependence of the retention index. I. Relation between equations.

The relation between the parameters of several equations for the retention index temperature dependence was established, taking the hyperbola deduced from the retention theory as starting point. The transformation factors depend only on methylene contributions to the thermodynamic functions of solution and temperature. Their evolution with the mean temperature of the range was illustrated for SE-30 and Carbowax-20M glass capillary columns. On this basis the post-run standardisation of dI/dT values at a reference mean temperature is possible. Examples and statistical correlation between series of parameters from different equations for perfumery solutes were shown.     

催化剂分子结构及共聚物配体的交替结构与其催化活性关系的理论研究

采用以ＡＳＥＤ－ＭＯ为基础的结构自动优化的ＥＨＴＯＰＴ法及Ｍｏｎｔｅ－Ｃａｒｌｏ法，对甲醇羰基化制乙酸的催化剂分子结构及共聚物配体的交替结构进行了理论研究。     

Relation between melting behavior and physical structure in polymers

The phenomenon of double melting, as manifested by two characteristic endotherms in the melting region on a differential thermal analysis (DTA) scan, has been studied in nylon 66 and polystyrene as a function of sample treatment by annealing or drawing. A variety of techniques were used in these studies including DTA, x-ray diffraction, electron microscopy, and mechanical testing. It is shown that the two endotherms are not caused by a bimodal crystal size distribution, by recrystallization, by orientation changes, or by phase changes. It is proposed that one endotherm is caused by the melting of foldedchain crystals, while the other is due to the melting of less perfect bundle crystals. This view is well supported by the results, especially by the DTA measurements made at different heating rates. Published data on the thermal behavior of annealed and drawn poly(ethylene terephthalate) and on polyethylene crystallized at various pressures may also be explained on this basis if it is allowed that in polyethylene the chains may be more extended.