一种新的耦合GTN模型以精确识别金属板料极限应变的三维M-K模型

为了精确识别金属板料的极限应变并提高成形极限预测精度,建立了一种新的耦合GTN模型的三维M-K模型,并命名为三维M-K-GTN模型。首先,通过引入摩擦应力和沿厚度方向上的法向应力,对经典M-K模型进行修正以使其适用于三维应力状态。随后,嵌入GTN模型以取代经验失效准则,将凹槽内孔洞体积分数累积到临界值时的应变作为极限应变。此外,考虑法向应力和摩擦应力,修正了孔洞形核与长大表达式。最后,预测成形极限曲线与实验获得的AA6016-T4板料极限应变的对比结果表明,三维M-K-GTN模型解决了大应变路径下预测结果明显高估的问题,且在每个给定的应变路径下都具有较高的预测精度。

High-level Expression and Purification of Human Zona Pellucida huZP3a^(22-176) and huZP3b^(177-348) Peptides in Escherichia coli

Objective To try making huZP3a^22-176 and huZP3b^177-348 polypeptides （representing an intact huZP^322-348 protein without its N-terminal signal peptide and C-terminal transmembrane domain ） express in E. coli at a higher level Methods The cDNAs encoding huZP3a and huZP3b were obtained with PCR method. The pBV221 plasmid was used to construct thermo-inducible recombinant expression vector. Purification of two target expression products employed an improved method of preparative gel polyacrylamide gel electrophoresis. Results Two polypeptides of recombinant huZP3a （rhuZP3a） and recombinant huZP3b （rhuZP3b） were all expressed respectively in an E. coli BL21（DE3）pLysS strain at a higher level, which were recognized by two specific polyclonal antisera in Western blotting test which recognize a linear B cell epitope present in rhuZP3a or rhuZP3b respectively. Using the shake-flask method, approximately 5 mg of rhuZP3a and rhuZP3b with more than 95% relative homogeneity were harvested from 1 L culture respectively. Conclusion The availability of two rhuZP3 polypeptides will help in detecting the immunogenicities of rhuZP3a and rhuZP3b through animal experiments and confirming the function domain of non-glycosylated huZP3 to induce acrosome reaction in vitro.

Correlation Analysis of the Results of Double Fluorescence(AO/PI) Staining and Clinical Outcomes

Objective To estimate the predictive value of double fluorescence [acridine orange （AO）/propidium iodide （PI）] staining results for fertilization rate and clinical outcomes and analyze the correlation between the results of AO/P1 staining and sperm apoptosis. Methods A prospective study was carried out, 235 infertile couples remedied using traditional in vitro fertilization （IVF） were included. Semen collected from 235 patients were stained by fluorescence dye, AO and PL at the same time the spermatozoa apoptosis rate was calculated by using flow cytometry to detect the rate of Annexin V＋/ PI- . The result of fluorescence was divided into 3 groups as green （G）, yellow （Y） and red （R） according to the color of fluorescence. The correlation between the percent of the 3 colors and clinical outcomes and spermatozoa apoptosis rate was evaluated. Results Significant negative correlation was observed between the percentage of Y and fertilization rate （r= -0.42, P=0.04）, no significant correlation was observed between the percentage of G, R and fertilization rate. The percentage of G, Y, R was not significantly different between pregnant patients and non-pregnant patients, respectiw,ly, while the percentage of Y was significant different between miscarriage patients and liveborn patients （r=0.6L P=0.01） and no significant difference exist in the percentage of G and R between liveborn patients and miscarriage patients. There was a significant positive correlation between the percentage of Y and the rate of Annexin V＋/ PI （r=0.53, P=0.04）, and no significant correlation was shown between the percentage of G, R and the rate of Annexin V＋/ PI-.Conclusion The percentage of yellow group of double fluorescence （AO/PI） staining will affect the fertilization rate and the miscarriage rate, and this group of spermatozoa may be connected with the spermatozoa apoptosis.

Effect of Spermatozoa Apoptosis on the Clinical Outcomes with Human in vitro Fertilization

Objective To analyze the effect of spermatozoa apoptosis on the clinical outcomes during in vitro Fertilization （IVF-ET）. Methods A prospective analysis was carried out, 519 infertile couples were divided into 3 groups according to the clinical outcomes with IVF, including pregnancy and birth （liveborn group）, pregnancy but abortion （miscarriage group）, failure to pregnancy （failure group）. Spermatozoa collected from 519 male partners were processed through density gradient centrifugation （DGC） and swim-up and the apoptosis of the spermatozoa, in ejaculated/processed semen, were evaluated using flow cytometry by determining the levels of disruption of mitochondrial membrane potential （d-MMP） and activation of caspase-3（CP3）Results For ejaculated semen, apoptosis was significantly different among .4 groups individually, the result was as follows： liveborn group 〈 failure group 〈 miscarriage group （P〈0.05）. For processed semen, miscarriage had the highest apoptosis level （P〈0.05）, and there was no significant difference between liveborn group and failure group （P〉0.05）. Compared with the d-MMP, the activation of CP3, either in ejaculated or processed semen, showed more powerful predictive value for miscarriage other than liveborn and failure. The cutoff value of CP3 in ejaculated semen was 42.0%, with sensitivity： 0.931, specificity： 0.804.Conclusion The level of apoptosis of spermatozoa played a strongly impact on the clinical outcomes with IVF and the activation of CP3 in ejaculated semen possessed a high predictive value for miscarriage.