Objective:To study the effects of different ratios between adhesive and solidification agent on the investment of titanium and to investigate the physical properties of the adhesive on different time intervals.Methods:Mixed adhesive with solidification agent according to different ratio:14∶1,14.5∶1,15∶1.Twelve wax sheet patterns(10 mm?10 mm?0.8 mm)were invested,and then the castings were fabricated.Manipulation performance,appearance of the casting mold,and color of the castings as well as their integrity and edge clarity were observed.The more ideal proportion was selected and determined.Dynamic viscosity,density and pH value of the adhesive were measured on different days(1,3,5 and 7 days).Results:With a adhesive or solidification agent ratio of 14∶1,the solidified time was comparatively short and unable to operate,while with a ratio of 15∶1,the solidified time was too long to solidify and led to the distorted castings.In group with a ratio of 14.5∶1,the primary gel time,intact mold and cast gate were appropriate.The surface of the castings showed bright,metal color after sand blasting.Dynamic viscosity,consistency and pH value of different days for the adhesive had no significant difference.Conclusion:Favorable casting can be fabricated for adhesive mixing with solidification agent when the ratio was 14.5∶1.The adhesive has steady capability in 7 days in practical condition.

Objective:To study the technical operation of self-developed investment (FUS-invest) for titanium crown and bridge. Methods:Orthogonal design was done. Four factors were taken into account, i.e. water/powder ratio, adhesive/hardener ratio, fine powder proportion in refractory and agitation time. And each factor was ranked into three levels. Slurry fluidity, initial setting time and setting time of every experiment group were studied. Grain size graduation of the best group was measured.Results:Fluidity, initial setting time and setting time were most greatly affected by water/powder ratio and secondly by fine powder proportion in refractory. When water/powder ratio was 7.5∶1 and the content of fine powder was 35%, slurry fluidity was better and initial setting time and setting time were appropriate. When the content of fine powder of AFS fineness number 300 was 31.31%, fineness number 100 was (40.09%), fineness number 70 was 18.05% and adhesive/hardness ratio was 200∶1, the perfect titanium castings could be fabricated. Conclution:The best rules of technical operation for perfect titanium castings are water/powder ratio (7.5)∶1, the content of fine powder 35% and adhesive/hardener ratio 200∶1.

Objective To optimize the process of extracting total saponins from Platycodon grandiflorum by orthogonal experimental design and central composite design-response surface method. Methods Independent variables were concentration of ethanol, reflux extraction time, reflux time and solvent fold. Dependent variables were extraction rate of total saponins in Platycodon grandiflorum and the yield of dry extract.Linear or nonlinear mathematic models were used to estimate the relationship between independent and dependent variables. Results The result of the orthogonal experimental design was 70%ethanol, 180 min for reflux, 6 fold of solvent and 2 times for extraction. The result of central composite design-response surface method was 70% ethanol, 140 min for reflux, 10 fold of solvent and 2 times for extraction. Conclusion The central composite design-response surface method is better than orthogonal experimental design in studying extraction process of Platycodon grandiflorum, which provides basis for feasibility of application of central composite design-response surface method in optimization of extraction process of Chinese traditional medicine.

Objective To observe the effect of pravastatin on the expression of heat shock protein B7 (HSPB7) in acute myocardial infarction (AMI) rats. Methods A total of 80 AMI rats were randomly divided into AMI group and pravas-tatin (P) group. Forty SD rats were used as sham operation (SH) group. Rats were then subdivided into 1 h, 3 h, 6 h and 12 h subgroups (10 for each group). Rats were not ligated after thoracotomy in SH group. The 1eft anterior descending coronary ar-tery was ligated in rats of AMI group. The 1eft anterior descending coronary artery was ligated in P group and given intragas-tric administration of 0.5 mg/(kg · d) pravastatin. The other groups were given the same amount of normal saline via gavage. The left ventricle infarcted myocardial tissues were taken at each time intervals. The corresponding myocardial tissues were harvested in sham-operated rats. The HSPB7 mRNA and protein expressions were measured by RT-PCR and immunohisto-chemistry respectively.Results The expression levels of HSPB7 mRNA and protein were significantly higher in the AMI group and P group than those of SH group(P<0.01). The expression levels of HSPB7 mRNA and protein were significantly increased 1 h after AMI and reached the peak value at 3 h after AMI. The expression levels of HSPB7 mRNA and protein were still higher in 6-h group and 12-h group than those of SH group. The expression levels of HSPB7 were higher in differ-ent time points of P group than those of AMI group. Conclusion HSPB7 could express in the early stage of acute myocardi-al infarction in rats. Pravastatin could promote the upregulation of HSPB7 in myocardial infarcted border zone after AMI, which may play a protective role in early myocardial infarction.