[Characteristics of particle size structure of plankton community in turbidity zone of near-shore waters, Liaoning Province of Northeast China].

Estuary and nearshore waters have complicated environment, where plankton community has a frequent feedback regulation and a very unstable particle size structure. In this paper, an investigation was made on the particle size structure of plankton in the turbidity zone of nearshore and port area waters in Liaoning Province of Northeast China. In the waters with high concentration inorganic nitrogen, phytoplankton biomass was mainly of small particle sizes, with the equivalent sphere diameter (ESD) being primarily 20-100 micro m, while in low nutrient waters, the phytoplankton biomass was mainly of larger size particles, with the ESD>100 micro m, indicating that the phytoplankton feedback regulation caused the phytoplankton community to be comprised of small sized organisms as part of the biological responses to high concentration suspended solids, which reduced the individual number of larger organisms such as Coscinodiscus. sp. and other species, and in turn, directly affected the fisheries resources, including a variety of fish and shrimp larvae fed on phytoplankton. A normalized biomass size spectrum with the characteristics of nearshore shallow aquatic oceanic ecosystems exhibiting eutrophication was constructed. The spectrum slope indicated that the plankton community biomass would gradually increase in size. The feasibility of using dinoflagellates and cladocerans as the bio-indicators for eutrophication was discussed.

Three new dammarane-type triterpene saponins from the leaves of Panax ginseng C.A. Meyer.

Three new dammarane-type triterpene ginsenosides, together with six known ginsenosides, were isolated from the leaves of Panax ginseng C.A. Meyer. The new saponins were named as ginsenoside Rh11, ginsenoside Rh12, and ginsenoside Rh13. Their structures were elucidated as (20S)-3ß,6α,12ß,20-tetrahydroxydammara-25-ene-24-one 20-O-ß-d-glucopyranoside (1), (20S)-3ß,12ß,20,24,25-pentahydroxydammarane 20-O-ß-d-glucopyranoside (2), and (20S,23E)-3ß,12ß,20,25-tetrahydroxydammara-23-ene 20-O-ß-d-glucopyranoside (3) on the basis of 1D and 2D NMR experiments and mass spectra. The known ginsenosides were identified as ginsenoside M(7cd), ginsenoside Rg6, ginsenoside Rb3, gypenoside XVII, gypenoside IX, and 20-(E)-ginsenoside F4.

[Effects of expansion fashion and expansion quantity on retention of cement-expanded composite screw post].

OBJECTIVE: To study the effects of expansion fashion and expansion quantity on retention of cement-expanded composition screw post (CECSP). METHODS: Ninety simulated tooth roots made of polymethylmethacrylate were divided into ten groups, each fashion induded five groups. The expanded plastic sheath of tricuspid valve was made with the special separated valve device and cemented and tightened up into root with the screw post at the same time by ZPC. Then the root and screw post-core system was tested by the speed of 10 mm/min on the INSTRON 4302 and the retention force was recorded. RESULTS: It appeared that the difference between different expansion fashion and different expansion quantity were significantly (P < 0.05). The retention of expansion fashion one was significantly greater than those of fashion two. The retention was best when expansion quantity was within 10%. CONCLUSION: During clinic operation, we should apply definite fashion and control the expansion quantity within 10%, and the screw post should tighten up to the bottom of prepared root.

[Fracture resistence force of the cement-expanded composite screw post-core system].

OBJECTIVE: This is a study comparing the effects of different post designs on the fracture resistence. METHODS: Twenty-seven simulated tooth roots made of polymethyl methacrylate (PMMA) were divided into three groups, then the cement-expanded composite screw post-core system (CECSP), cement screw post-core system (CSP) and cast metal post-core system (CMP) were manufactured. The root and post-core system was compressed by the speed of 1 mm/min on the Instron 4302 and the fracture resistence force was recorded. RESULTS: Statistical analysis of the measured values showed the fracture resistence force of CECSP and CMP to be significantly greater than that of CSP (P < 0.05), but there was no significant difference between the fracture resistence force of CECSP and CMP (P > 0.05). CONCLUSION: The fracture mechanical properties of CECSP are much better than those of cement screw post-core system and are similar to cast metal post-core system. Therefore, it is possible to find a new way for restoration of endodontally treated teeth.