Assisted Hatching in Couples with Advanced Maternal Age： A Systematic Review and Meta-analysis

This systematic review aimed to evaluate the efficacy and safety of assisted hatching （AH） performed in couples with advanced maternal age. We searched for randomized controlled trials （RCTs） in electronic databases, including MEDLINE, EMBASE and CENTRAL （from inception to January 2018）; in addition, we hand-searched the reference lists of included studies and similar reviews. We included RCTs comparing AH versus no treatment （control）. The meta-analysis was performed by RevMan 5.3 software. The search retrieved 943 records and 8 RCTs were included, comprising 870 cycles （n=440 for AH, and n=430 for control）. There was no significant difference in the rates of live birth （RR 0.88, 95% CI 0.65 to 1.18, 3 RCTs, n-427,I^2=0%）, clinical pregnancy （RR 1.00, 95% CI 0.83 to 1.19, 8 RCTs, n=870, I^2=22%）, implantation （RR 1.07, 95% CI 0.83 to 1.39, 4 RCTs, n=1359, I^2=0%）, miscarriage （RR 1.13, 95% CI 0.66 to 1.94, 2 RCTs, n=116, I^2=0%） and multiple pregnancy （RR 0.89, 95% CI 0.31 to 2.52, 1 RCT, n=97,I^2=not applicable） between the treatment group and control group. No reasonable conclusions could be drawn regarding reproductive outcomes after AH in patients with advanced maternal age due to the small sample pooled in meta-analyses. Studies of high methodological quality and with adequate power are necessary to further investigate the value of AH in assisted conception of those patients.

Enhanced mechanical performance of gradient-structured CoCrFeMnNi high-entropy alloys induced by industrial shot-blasting

In this study,CoCrFeMnNi high-entropy alloys(HEAs)with a surface gradient nanostructure were produced using industrial shot blasting,which improved their mechanical properties compared to the untreated alloy.The severely plastically deformed(SPD)surface layer had a multi-scale hierarchical structure with a high density of stacking faults,deformation nanotwins,and amorphous domains.The depth of the SPD layer steadily increased as the shot-blasting time increased.The differences in the microhardness and tensile strength before and after shotblasting demonstrated the significant effect of the SPD layer on the mechanical performance.The microhardness of the homogenized HEA was~5 GPa.In comparison,the maximum microhardness of the specimens after 20 min of shot blasting was~8.0 GPa at the surface.The yield strength also improved by 178%,and a large ductility of~36%was retained.Additional nanograin boundary,stacking fault,and twin strengthening within the gradientnanostructured surface layer caused the strength to increase.During tensile deformation,strain concentration began at the surface of the specimen and gradually spread to the interior.Thus,the gradient-nanostructured surface layer with improved strain hardening can prevent early necking and ensure steady plastic deformation so that high toughness is achieved.

Pair production in inhomogeneous electric fields with phase modulation

Electron-positron pair production in spatial inhomogeneous electric fields with sinusoidal phase modulation is studied within the Dirac-Heisenberg-Wigner formalism.The focus is on discussing the effects of the modulation parameters on the momentum spectrum and the reduced particle number at various spatial scales.For the momentum spectrum,the interference effect becomes more and more remarkable with the increase of modulated amplitude or frequency,while the symmetry is severely destroyed with modulated amplitude.For the reduced particle number,it is greatly enhanced by about a few times and evenly one order of magnitude when modulation parameters are applied.Moreover,the effect of spatial scales on the reduced particle number is carefully examined,and it is found that it increases rapidly at small spatial scales,while it tends to be a constant at large spatial scales.We also obtain the optimal pair production that can be achieved through different modulations.These results can provide a possibility for realizing the optimal pair production by combining the advantages of field spatial inhomogeneity with different choices of phase modulation.

Proportion of Uterine Malignant Tumors in Patients with Laparoscopic Myomectomy： A National Multicenter Study in China

Background： The Food and Drug Administration recently announced that the use of morcellation may cause fibroids or pelvic dissemination and metastasis of uterine sarcoma; therefore, the use of morcellation is limited in the USA. A large sample study is necessary to assess the proportion of uterine malignant tumors found in patients with laparoscopic myomectomy. Methods： A national multicenter study was performed in China. From 2002 to 2014, 33,723 cases were retrospectively selected. We calculated the prevalence and recorded the clinical characteristics of the patients with malignancy after morcellation application. A total of 62 cases were finally pathologically confirmed as malignant postoperatively. Additionally, the medical records of the 62 patients were analyzed in details. Results： The proportion of postoperative malignancy after morcellation application was 0.18% （62/33,723） for patients who underwent laparoscopic myomectomy. Nearly 62.9% （39/62） of patients had demonstrated blood flow signals in the uterine fibroids before surgery. And, 23 （37.1%） patients showed rapid growth at the final preoperative ultrasound. With respect to the pathological types, 38 （61.3%） patients had detectable endometrial stromal sarcoma, 13 （21.0%） had detectable uterine leiomyosarcoma, only 3 （3.2%） had detectable carcinosarcoma, and 5 （8.1%） patients with leiomyoma had an undetermined malignant potential. Conclusions： The proportion of malignancy is low after using moreellation in patients who undergo laparoscopie myomectomy. Patients with fast-growing uterine fibroids and abnormal ultrasonic tumor blood flow should be considered for malignant potential, and morcellation should be avoided.

Microstructural Features and Mechanical Behaviors of Al_(0.5)Cr_(0.8)CoFeNi_(2.5)V_(0.2) High-Entropy Alloys Fabricated by Selective Laser Melting Technique

In this work,high strength and ductile Al_(0.5)Cr_(0.8)CoFeNi_(2.5)V_(0.2) high-entropy alloys(HEAs)were fabricated by the selective laser melting(SLM)technique.After orthogonal experiments,it was verified that a wide SLM processing parameter window can be used to produce crack-free samples for the investigated HEAs.All the printed HEA samples exhibit good densification higher than 98.3%.It was found that obvious epitaxial growth leads to the formation of the cylindrical and equiaxed ordered face-centered cubic(FCC)crystals,displaying the characteristics of sub-cylindrical and sub-cellular microstructures.The low-angle grain boundaries(LAGBs)prefer appearing around subgrain structures,while the high-angle grain boundaries(HAGBs)tend to form around coarse grains.Two HEA samples with high and low apparent densities were selected to observe their mechanical properties,which exhibit Vickers hardness higher than 263 HV and do not fail during compression.With increasing densification,the strength gradually rises.According to the engineering stress–strain curves during compression,the yield strength is higher than 530 MPa,while the strength near 40%engineering strain is larger than 1840 MPa.During deformation,a large density of dislocations becomes popular within subgrain structures together with the pre-existing dislocations from rapid solidification,leading to the formation of planar and cross slip bands.Within coarse cylindrical crystals,some deformation twins are also induced together with the appearance of a distinct copper-type texture during deformation.As a result,the as-printed samples display better mechanical properties than the as-cast counterpart.The present studies provide a very good HEA candidate for the SLM process,but more work should be conducted to achieve excellent comprehensive properties.

Chinese Expert Consensus on Clinical Application of Female Contraceptive Methods

Unintended pregnancy is a global issue, with approximately 85,000,000 women around the world having unintended pregnancy annually. The contents of clinical application of women’s contraceptive methods are very wide, involving multiple areas. This consensus deeply discusses the specific contraceptive needs at different statuses, combined with gynecological diseases, postabortion contraception, and postpartum family planning, ensuring the correct use of contraceptive methods under the corresponding status. The top priority of the consensus is the specific contraception consensus section for women combined with gynecological diseases because medical treatment effect as well as side effects should be weighed carefully. The consensus is to make high-efficiency and individual contraceptive strategy for different groups based on multidisciplinary(gynecology, obstetrics, and family planning) and multidimensional aspects, which can provide uniform guidance for medical and health organizations under the condition as relevant global guidance or consensus is still lacking.