Apparent density and tensile strength of materials for facially butted porcelain margins

The study focused on comparison of the as-fired density and tensile strength of unmodified and modified porcelains used for construction of facially butted porcelain margins. The respective densities and tensile strengths of unmodified body and shoulder porcelains were found to be comparable. Also statistically equivalent were the measured properties of specimens made from either an unmodified shoulder-porcelain formulation or shoulder-porcelain powder--aqueous sodium silicate solution mixtures. On the other hand, the respective densities and tensile strengths of body porcelain-resin and shoulder porcelain-wax combinations were significantly lower (p less than 0.05) than those of their unmodified counterparts. Low density and tensile strength limit the rational use of wax or resin-modified porcelains to final bakes for correcting small, troublesome labiogingival discrepancies.     

Effect of medial arch-heel support in inserts on reducing ankle eversion: a biomechanics study

Background  

Excessive pronation (or eversion) at ankle joint in heel-toe running correlated with lower extremity overuse injuries. Orthotics and inserts are often prescribed to limit the pronation range to tackle the problem. Previous studies revealed that the effect is product-specific. This study investigated the effect of medial arch-heel support in inserts on reducing ankle eversion in standing, walking and running.     

Inulin as filler-binder for tablets prepared by direct compaction.

The tabletting properties of a number of different amorphous inulin types were investigated. The types varied with respect to chain length, particle size and amount of included air in the particles. Powder flow properties and densities of the different types were investigated. Just as expected, it was found that the flow properties improved with increased particle size of the material. Compactibility was investigated by compression of tablets on a compaction simulator, simulating the compression on high-speed tabletting machines. The bonding capacity of all inulins was high. However, the lubricant sensitivity strongly varied among the different types of inulin. Generally, amorphous materials such as starches are highly lubricant sensitive, because they show ductile behaviour upon compaction. On the other hand, crystalline materials such as dicalcium phosphate dihydrate have a low lubricant sensitivity, because they fragment during compaction. A high lubricant sensitivity was indeed found for amorphous inulins with a low amount of entrapped air. In contrast, the lubricant sensitivity of the amorphous inulin was low when particles containing large amounts of air were compressed. Obviously entrapped air induces fragmentation of the powder particles by which the lubricant film, covering the particles, was destroyed. Tablets prepared from inulin did not disintegrate but they dissolved when incubated in water. The disintegration/dissolution time increased with decreasing chain length of the inulin. The addition of a disintegrant reduced the disintegration time. The somewhat slower dissolution of the longer chain inulin can be an advantage for chewable tablets or lozenges. It was concluded that inulin with large amounts of entrapped air is a good filler-binder and an attractive alternative to commonly used filler-binders.     

苦楝化学成份的研究

从苦楝(Melia azedarach L.)果中分得苦楝新醇(Ⅰ),苦楝醇(Ⅱ)、苦楝酮(Ⅲ)、苦楝二醇(Ⅳ)、香草醛(Ⅴ)和香草酸(Ⅵ)。根据波谱(IR,MS,¹HNMR,¹³CNMR)分析和理化常数测定,确定了它们的结构。其中苦楝新醇(Ⅰ)为新化合物,对菜青小虫有一定的拒食活性。     

多波长系数法的研究与应用

在多组分光度分析的方法中,最小二乘法、Kalman滤波、因子分析等虽已能成功的消除组分间的相互干扰,不经分离直接定量,但均需有微机配套进行矩阵运算。而双波长、三波长法,虽然简单,但对于吸收光谱重叠严重的混合组分,则难以选出满足要求的波长;