Collagen membrane preparations were manufactured with the aim of enhancing wound healing following periodontal surgery. After crosslinking by various processing methods (with ultraviolet and hexamethylenediisocyanate) and to various extents, two types of collagen (atelocollagen and tendon collagen) were implanted into a dissection site within palatal gingival tissue. The time course of healing responses was investigated histologically. Collagen implantation was found to accelerate fibrous connective tissue attachment to the root surface and inhibit apical migration of the junctional epithelium. Cross-linked atelocollagen was superior in biocompatibility to the other collagen membranes studied.

planet in our Solar System is Jupiter and why there are none more massive is not understood. The lifetime of our gaseous proto-planetary disk may have been short 28 or the disk may have been tidally truncated by the growing planet itself 29 • Good statistics on the population of EGPs will better constrain protoplanetary disk processes. The absence of a Jupiter-class planet in a planetary system would imply a very different population of cometary-sized planetesimals than exists in our own Solar System, and this may have important implications for the origin, evolution and survival of life on rocky 'terrestrial' planets 30 .Only sensitive and systematic searches, such as those we anticipate over the next decade, will directly address these important issues of planet formation. D RECENT work 1 ' 2 has shown that superconducting copper oxyhalides can be synthesized, with the La 2 Cu0 4 structure but with no oxygen in the 'apical' positions outside the Cu0 2 planes. For these materials to be rendered superconducting, charge carriers must be introduced into the Cu0 2 planes; in previous work, positive carriers (holes) have been introduced by the incorporation of interstitial fluorine in Sr 2 Cu0 2 F z+O (transition temperature Tc = 46 K) 1 , or by the substitution of sodium for calcium in (Ca,Na)zCuOzCiz (Tc = 26 K) 2 . Here we present an alternative doping approach for this copper oxyhalide family: holes are introduced by partially replacing the (monovalent) halogen that occupies the apical sites with (divalent) oxygen. We have obtained bulk superconductivity with Tc above 77 K in a new double-layer compound (Sr,Ca) 3 Cuz0 4 +0Ciz-y, which is isostructural with (La,Sr)z-CaCu206 (ref.3), with (Sr,Ca) at the (La,Sr) orCa sites, and Cl at the apical sites outside the Cu02 planes.We synthesized Sr 3 -xCaxCu 2 0 4 +5Cl 2 -y compounds using a high-pressure, high-temperature technique, which has proven effective in searching for new homologous series of high-Tc superconducting copper oxides 4 -6 . The precursors Sr 2 Cu0 3 , SrCu0 2 and Ca 2 Cu0 3 were prepared by solid-state reaction between CuO and SrC0 3 or CaC0 3 (each 99.9% pure). Precursor Sr 2 Cu0 2 CI 2 (CI source of the sample) was obtained by the reaction between CuO and fully dehydrated SrCI 2 (99% pure)

Our results suggest that osteoblasts, as well as cells in periodontal ligament and gingival epithelium, respond to mechanical stress loaded by low-intensity pulsed ultrasound, and that ultrasound accelerates periodontal wound healing and bone repair.

Both the Young`s modulus sound velocity (VE) and the internal friction (Q-1) have been measured for a polycrystalline sample of LiMn2O4 in the temperature range between 35 and 350 K, using a vibrating-reed technique. The resonance frequency (fr) employed for the measurement ranged from 0.81 kHz to 2.69 kHz at 300 K. At fr(300 K)=0.81 kHz, as temperature is lowered from 350 K, VE decreases down to 225 K (TA) Then, VE increases rapidly but monotonically with lowering temperature, though the magnitude of the slope (-dVE/dT) reduces. The overall increase in the velocity between TA and 100 K is about 68%. In the Q-1-versus-T curve, a large peak is clearly observed at around 210 K, as is the forming of a large shoulder on the low-temperature side; additionally, there exists a small Q-1 peak at around 120 K, though VE indicates no significant change at around 120 K. Furthermore, both the VE-versus-T curve and the Q-1-versus-T curve shift toward the higher-temperature side, by ~45 K and ~25 K, as fr(300 K) is increased from 1.32 kHz to 2.69 kHz. The observed elastic anomalies suggest that a phase transition occurs at temperatures below 290 K. This phase transition is probably due to an ordering of Mn3+ and Mn4+ ions on the octahedral 16d site in the spinel lattice. On the other hand, the origin of the Q-1 peak is considered to lie in a stress-induced relaxation of the distributions of Mn ions or Li ions.

We analyzed nutrient levels in amniotic fluid obtained during the second trimester of normal, uncomplicated pregnancies from 221 women who delivered apparently healthy infants and from 8 with neural tube defect (NTD) pregnancies. Folate was measured by microbiological assay, vitamin B₁₂ by a radiobinding method, and zinc, copper and iron by atomic absorption spectrophotometry. We found that the mean amniotic fluid nutrient levels of normal pregnancies were 24.7nmol/l for folate, 600pmol/l for vitamin B₁₂, and 1.7, 1.9, and 9.0 μmol/l for zinc, copper and iron, respectively. Amniotic fluid folate, zinc, copper and iron levels of NTD pregnancies were similar to those found during normal pregnancy, however, vitamin B₁₂ levels were markedly lower than those of normal pregnancies.