Biomedical subjects

Zhimin Zhu

Publications and source records attributed to Zhimin Zhu.

6 recordsLinked to original sources

PubMed2006

Population dynamics of the water mite Unionicola arcuata (Unionicolidae) in the freshwater bivalve Cristaria plicata (Unionidae) in Poyang Lake, eastern China.

Population dynamics of the water mite Unionicola arcuata were investigated in the freshwater bivalve Cristaria plicata during the period from January to December 2002 in Poyang Lake, East China. A pattern of seasonal variation was observed, with prevalence and abundance peaking in early spring and autumn. The number of mites in individual hosts was significantly correlated with the size, but not with the sex, of bivalves. The change in infection level of mites on different infection sites in C. plicata was significant, with >58% of the mites found on the outer and inner gills, indicating that U. arcuata shows site preference.

Acari↗

PubMed2005

[Effect of erosion on strength of dental infiltrated Al2O3 ceramics].

The objective of the research is to investigate the elements of routine sandblast technique on the evolution of bending strength of dental infiltrated Al2O3 ceramics and the underlying erosion mechanism. The plane specimens of an infiltrated ceramic were manufactured, polished and then tested under the modified pen-like sandblasting apparatus (90 degrees erosive angle and 10 mm sandblasting distance), with different grit sizes, working pressure and disposing time. Half of samples were selected randomly and sintered subsequently with Vitadur alpha veneering porcelain. Before and after sintering, the three-point-bending strengths was measured, and the surfaces of dental porcelain were observed with SEM and LCSM. The bending strength of ceramics decreased significantly after sandblast as compared with that of empty control group. After the procedure of sintering the veneering porcelain, the descending evolution of bending strength slowed down. Under the present manufacturing conditions, grit size effect is prominent among those correlative elements of sand grit size, working pressure and disposing time. And fatigue cracking characterizes the mechanism of erosion of dental infiltrated Al2O3 ceramics.

Aluminum Oxide↗

PubMed2003

[The effect of cryotreat on the wear resistance of the medium melting-point castable alloy].

OBJECTIVE: The purpose of this study was to introduce cryotreat technique into prosthetic dentistry by investigating the wear resistance changes of SDA-II medium melting-point castable alloy before and after cryotreat. METHODS: 15 samples were divided into three groups, i.e. control group, cryotreat group, cryotreated plus post-cryogenic treat group. Weight loss measurement was used to examine the wear resistance. RESULTS: For SDA-II medium melting-point castable alloy, cryotreat effectively improved its wearing resistance; so far as the wear resistance was concerned, the post-cryogenic treatment was unnecessary. CONCLUSION: The results obtained above suggest that cryotreat was an effective method in enhancing the wear resistance of SDA-II medium melting-point castable alloy.

Cold Temperature↗

PubMed2003

[The influences of metal-ceramic restoration margins on gingival health].

OBJECTIVE: Today metal-ceramic restorations are widely accepted in dental practice because of their good aesthetic and biocompatible properties, but there are still several problems to be resolved, among which the influences of their margins on gingival health is noticeable. The purpose of this study was to investigate the influences of metal-ceramic restoration margin on gingival health. METHODS: 129 abutments of metal-ceramic restorations, including their margins' fitness, location and smoothness were examined and their influences on gingival health were analyzed. RESULTS: There was a close relation between the metal-ceramic restorations' margins and the gingival health. CONCLUSION: In order to maintain the gingival health, the margins should be smooth, closely fitted, no overhanging and in a moderate location (i.e. not below the gingival more than 1 mm).

Female↗

PubMed2002

Common developmental requirement for Olig function indicates a motor neuron/oligodendrocyte connection.

The oligodendrocyte lineage genes Olig1 and Olig2 encode related bHLH proteins that are coexpressed in neural progenitors. Targeted disruption of these two genes sheds light on the ontogeny of oligodendroglia and genetic requirements for their development from multipotent CNS progenitors. Olig2 is required for oligodendrocyte and motor neuron specification in the spinal cord. Olig1 has roles in development and maturation of oligodendrocytes, evident especially within the brain. Both Olig genes contribute to neural pattern formation. Neither Olig gene is required for astrocytes. These findings, together with fate mapping analysis of Olig-expressing cells, indicate that oligodendrocytes are derived from Olig-specified progenitors that give rise also to neurons.

Animals↗

PubMed2002

[Effects of cryotreat on the corrosion resistance of the medium melting-point castable alloy].

OBJECTIVE: The purpose of this study was to investigate effects of cryotreat on the corrosion resistance of SDA-II medium melting-point castable alloy. METHODS: 12 samples were divided into three groups, including the control group, the cryotreated group and the cryotreated & post-cryogenic treated group. The cryotreating process was firstly dropping the temperature from room temperature to -170 degrees C with dropping rate 3 degrees C/min, maintaining -170 degrees C for 2 hrs, and then returning to ambient temperature with an increasing rate of 1 degree C/min. The post-cryogenic process was maintaining the samples in 300 degrees C for 1 hr. Finally, all samples were subjected to the electrochemical potentiodynamic polarization after immersed in the artificial saliva (ISO/TR 10271: 1993 (E), pH 6.8) for 24 hrs at ambient temperature. The exposing area of each sample was 10 mm x 10 mm. The electrochemical tests were carried out in the artificial saliva under 37 degrees C, with the scanning rate of 20 mV/min, starting potential -200 mV below OCP and stopping current 10(-3) A. The corrosion currents (Icorr), the pitting corrosion potentials (Eb) and the potentiodynamic polarization curves were observed using the 283 electrochemical corrosion measuring system automatically. RESULTS: For SDA-II medium melting-point castable alloy, cryotreat reduced corrosion rate of the alloy, but had no effect on the pitting corrosion potential. As far as the post-cryogenic treatment, it didn't affect the corrosion resistance. CONCLUSION: The results suggested that cryotreat was an effective procedure in enhancing the corrosion resistance of SDA-II medium melting-point castable alloy, and it may be applicable in prosthetic dentistry.

Cold Temperature↗