RESUMO
In order to examine the mechanical properties and rotational bending fatigue performance of 40CrNi2MoE steel subsequent to tempering at varying temperatures, the steel specimen was subjected to tempering within the range of 400~460 °C. SEM, EBSD, and TEM were used to analyze the microstructure as well as precipitates. The strain hardening law was studied using the modified Crussard-Jaoult method. Investigations were undertaken to reveal the rotational bending fatigue life with respect to the tempering temperature. The findings indicate that the strength and fatigue life of the examined steels exhibit a decline as the tempering temperature increases, with the primary factor affecting this trend being the alteration in dislocation density. No notable impact on the fatigue fracture morphology exerted by tempering temperature was found within the range of the experiment. The C-J model analysis reveals that the work-hardening behavior of the trial steels is influenced by dislocations and the second phase.
RESUMO
OBJECTIVE: To evaluate the curative effect of electroacupuncture(EA) of Zigong (EX-CA 1) and Tianshu (ST 25) and acupuncture of Sanyinjiao (SP 6) and Guanyuan (CV 4) for perimenopausal syndrome(PMS). METHODS: Fifty-eight PMS patients were equally and randomized into acupuncture group and medication group. EA (10 Hz/50 Hz, 30 min in duration) was applied at Zigong (EX-CA 1) and Tianshu (ST 25) in combination with manual acupuncture stimulation of Sanyinjiao (SP 6) and Guanyuan (CV 4) by twirling the acupuncture needles with small amplitude and till deqi. The treatment was conducted once every other day, three times a week, 8 weeks altogether. The patients of the medication group were asked to take estradiol valerate (1 mg/time, qd) for 3 weeks, then, to have one week's rest and continuously took estradiol valerate(1 mg/d) and medroxyprogesterone 17-acetate (8 mg/d) for 10 days. The therapeutic effects were assessed by Menopause Rating Scale Questionnaire[MRS, composing of 3 areas:somatic (4 items), psychological(4 items) and urogenital (3 items) domain]. Serum estradiol (E2), follicle stimulating hormone(FSH) and luteotrophic hormone (LH) contents were assayed using ELISA. RESULTS: After the treatment, the scores of the MRS and the contents of serum FSH and LH were significantly decreased in both the acupuncture and medication groups (P<0.01), and serum E2 contents significantly increased in the two groups (P<0.01). No significant differences were found between the two groups in the total effective rates (P>0.05). Eight weeks' follow-up showed that the MRS score of the acupuncture group was significantly lower than that of the medication group (P<0.05). Of the two 29 PMS patients in the medication and acupuncture groups, 3 (10.3%) and 2 (6.9%) cases were under control, 22 (75.9%) and 21 (72.4%) experienced a marked improvement in their symptoms, 3 (10.3%) and 4(13.8%) were effective, 1 (3.4%) and 2(6.9%) invalid, with the effective rates being 96.6% and 93.1%, respectively. Eight weeks' follow-up showed that the long-term effect of the acupuncture therapy was obviously superior to that of the medication (P<0.05) according to MRS score. CONCLUSIONS: Acupuncture therapy is effective in relieving clinical symptoms of PMS women by regulating endocrine hormones, being similar to medication.
