Major advances in laser technology at LLE have included the demonstration of high-efficiency frequency doubling and tripling of fusion lasers1 and the development of short-pulse, chirped-pulse-amplification (CPA) lasers2 These technologies were combined a few years ago with the demonstration of 75% efficient frequency doubling of 1.6-ps laser pulses on the CPA T~ (table-top terawatt) system at ...

In this study, calcium phosphate nanoparticles with two phases, fluorapatite (FA; Ca(10)(PO(4))(6)F(2)) and hydroxyapatite (HA; Ca(10)(PO(4))(6)(OH)(2)), were prepared using the solgel method. Ethyl phosphate, hydrated calcium nitrate, and ammonium fluoride were used, respectively, as P, Ca, and F precursors with a Ca:P ratio of 1:72. Powders obtained from the sol-gel process were studied after...

Preliminary studies of the wear of fluorapatite single crystals subjected to sliding neglected the possible influence of crystallographic direction on the frictional behavior and surface failure of the basal plane.1-3 In these studies, possible anisotropic effects were considered to contribute to the experimental error in the analysis of the data. Buckley4 has observed that friction coefficient...

Historically, the study of the wear of hard dental tissues in modern man has been limited to clinical observation of physiologic and pathologic conditions that lead to wear, and to attempts to duplicate the effects of hygienic procedures such as the use of toothbrush and dentifrice on hard dental tissues in the laboratory. However, several fundamental investigations have been reported in which ...

The process of enamel biomineralization is multi-step, complex and mediated by organic molecules. The lack of cells in mature enamel leaves it unable to regenerate and hence novel ways of growing enamel-like structures are currently being investigated. Recently, elastin-like protein (ELP) with the analog N-terminal sequence of statherin (STNA15-ELP) has been used to regenerate mineralized tissu...

Microgastropod fauna from the Upper Devonian Cephalopod Bed and overlying Lower Tournaisian strata of the original reference section of the Shishtu Formation have been examined. Twenty genera and one unknown genus have been identified. The original aragonite shells have been replaced either by pyrite or fluorapatite

The teeth of two different shark species (Isurus oxyrinchus and Galeocerdo cuvier) and a geological fluoroapatite single crystal were structurally and chemically characterized. In contrast to dentin, enameloid showed sharp diffraction peaks which indicated a high crystallinity of the enameloid. The lattice parameters of enameloid were close to those of the geological fluoroapatite single crysta...

Various authors have shown that the caries decline in the industrialized countries during recent decades is based on the use of fluorides, of which local fluoride application in the form of fluoridated toothpastes is of primary importance. The caries-protective potential of fluorapatite is quite low; in contrast, dissolved fluorides in the vicinity of enamel are effective both in promoting remi...