检索结果-南通市图书馆

Single-metal-atom site with high-spin state embedded in defective BN nanosheet promotes electrocatalytic nitrogen reduction

引用

Nano Research 2021年第11期14卷 4211-4219页

作者： cong fang Wei An College of Chemistry and Chemical Engineering Shanghai University of Engineering ScienceShanghai201620China

Single-atom catalysts (SACs) especially supported on two-dimensional nitrogen-doped carbon substrate have been widely reported to be able to effectively promote electrocatalytic N_(2) reduction reaction (eNRR). The precise design of single-metal-atom active site (SMAS) calls for fundamental understanding of its working mechanism for enhanced eNRR performance. Herein, by means of density functional theory calculations, we theoretically investigate the eNRR performance of nine prototypical SMAS, namely, MN_(2)B_(2) (M: transition metals of IIIB, IVB and VB groups) which comprises of asymmetric ligands of N_(2)B_(2) embedded in defective BN nanosheet. Our results reveal the significant role of spin state of SMAS in tuning the potential-determining steps of eNRR, in which MN_(2)B_(2) site with higher spin magnetic moment (μ) is beneficial to reducing limiting potentials (U_(L)) of eNRR. Specially, CrN_(2)B_(2) (μ = 4μB), VN_(2)B_(2) (μ = 3μB) and MoN_(2)B_(2) (μ = 2μB) demonstrate high activity and selectivity to eNRR. The asymmetric ligands of N_(2)B_(2) are deemed to be superior over mono-symmetric ligands. More importantly, our results demonstrate that breaking (or deviating) of the scaling relations between key N-containing intermediates (*N_(2)H/*N_(2) and *NH2/*N_(2)) on MN_(2)B_(2) can be realized by enhancing spin state of SMAS which renders the active site a balanced N-affinity critical for efficient eNRR. This observation is validated by the calculated Sabatier volcano-shape relation between eNRR limiting potentials and N_(2) adsorption energy. Our study develops the guidance for catalyst design to boost eNRR performance by tuning the spin state of an active site.

关键词： electrocatalysis N_(2)reduction BN nanosheet spin state single-atom catalyst jdensity functional theory(DFT)

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Clinical application of the endometrial microbiota test combined with personalized treatment in patients with repeated implantation failure

引用

生殖与发育医学(英文) 2024年第1期08卷 18-23页

作者： Chen Rou-Zhu Wang Yan-fang Chen Pei-Gen fang cong Li Ting-Ting Reproductive Medicine Center The Sixth Affiliated Hospital 3. Sun Yat-sen University 4. Guangzhou 510655 5. China

Objective: The objective of this study was to investigate the clinical value of the endometrial microbiota test (EMT) combined with personalized treatment in patients with repeated implantation failure (RIF).Methods: From March 2019 to August 2022, the clinical data of patients with RIF at the Reproductive Medicine Research Center of the Sixth Affiliated Hospital of Sun Yat-sen University were retrospectively analyzed. A total of 356 patients underwent the EMT using 16S rRNA sequencing and were included in the EMT group. The SPSS statistical software propensity score was set at 1:1 to match the age, anti-Müllerian hormone (AMH), antral follicle count (AFC), years of infertility, and body mass index (BMI) of the women who had not undergone the EMT; subsequently, 354 patients were classified in the non-EMT group. We compared the clinical characteristics of the two groups and analyzed the clinical pregnancy outcomes after personalized treatment.Results: The clinical pregnancy rate (CPR) of the EMT group was significantly higher than that of the non-EMT group (47.81%vs. 13.38%,P <0.05). Among 356 patients who underwent the EMT, 55 patients (15.45%) in group A with normal endometrial microbiota composition did not test positive for the pathogenic bacteria causing chronic endometritis, 34 patients (9.55%) in group B with abnormal endometrial microbiota composition did not test positive for the pathogenic bacteria causing chronic endometritis, 35 patients (9.83%) in group C with normal endometrial microbiota composition tested positive for the pathogenic bacteria causing chronic endometritis, and 232 patients (65.17%) in group D with abnormal endometrial microbiota composition tested positive for the pathogenic bacteria causing chronic endometritis. After administration of probiotics or antibiotic plus probiotics treatment, the pregnancy rates of groups C and D were higher than those of group A (44.00%vs. 20.00% and 55.03%vs. 20.00%, respectively; bothP <0.05).Conclusion: The EMT combined with personalized treatment in

关键词： Endometrial microbiota test Assisted reproductive technology Repeated implantation failure Personalized treatment

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Machine learning-based prediction of pregnancy outcomes in couples with non-obstructive azoospermia using micro-TESE for ICSI: a retrospective cohort study

引用

生殖与发育医学(英文) 2024年第1期08卷 24-31页

作者： Jia Lei Chen Pei-Gen Chen Li-Na fang cong Zhang Jing Chen Pan-Yu Reproductive Medicine Center The Sixth Affiliated Hospital 3. Sun Yat-sen University 4. Guangzhou 510275 5. China

Objective: To develop a clinically applicable tool for predicting clinical pregnancy, providing individualized patient counseling, and helping couples with non-obstructive azoospermia (NOA) decide whether to use fresh or cryopreserved spermatozoa for oocyte insemination before microdissection testicular sperm extraction (mTESE).Methods: A total of 240 couples with NOA who underwent mTESE-ICSI were divided into two groups based on the type of spermatozoa used for intracytoplasmic sperm injection (ICSI): the fresh and cryopreserved groups. After evaluating several machine learning algorithms, logistic regression was selected. Using LASSO regression and 10-fold cross-validation, the factors associated with clinical pregnancy were analyzed.Results: The area under the curves (AUCs) for the fresh and cryopreserved groups in the Logistic Regression-based prediction model were 0.977 and 0.759, respectively. Compared with various modeling algorithms, Logistic Regression outperformed machine learning in both groups, with an AUC of 0.945 for the fresh group and 0.788 for the cryopreserved group.Conclusion: The model accurately predicted clinical pregnancies in NOA couples.

关键词： Cryopreserved spermatozoa Fresh spermatozoa Logistic regression Microdissection testicular sperm extraction

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

基于软电离质谱技术的金属纳米团簇合成、结构解析与催化反应机理研究的进展

引用

质谱学报 2024年第1期45卷 69-89,I0003页

作者：张丽丽周健房聪孙晓岩中国科学院青岛生物能源与过程研究所山东青岛266101 中国科学院大学北京100049 山东能源研究院山东青岛266101 青岛新能源山东省实验室山东青岛266101

原子数精确的金属纳米团簇为研究纳米材料的结构演化和构效关系提供了绝佳模型,然而,由于团簇生长过程的不确定性、结晶过程的复杂性以及自身稳定性较差等因素,使其在精准合成、结构解析以及催化机理研究方面面临挑战。质谱技术具有高... 详细信息

原子数精确的金属纳米团簇为研究纳米材料的结构演化和构效关系提供了绝佳模型,然而,由于团簇生长过程的不确定性、结晶过程的复杂性以及自身稳定性较差等因素,使其在精准合成、结构解析以及催化机理研究方面面临挑战。质谱技术具有高分辨率、高灵敏度、快速响应的特性,尤其是结合软电离技术(主要包括电喷雾电离和基质辅助激光解吸电离),近年来在凝聚相团簇研究中发挥着重要作用。例如,通过监测中间体的变化可以解析团簇的生长过程,使用串联质谱技术可以推测团簇结构特征,利用离子-分子反应方法以及在线反应监测技术能够揭示催化反应微观机理等。本文主要总结了2种软电离质谱技术在金属团簇合成、结构解析以及催化反应机理研究的进展,并展望其应用前景。

关键词：金属纳米团簇质谱实时监测反应中间体

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Basal Serum Anti-Miillerian Hormone Level as a Predictor of Clinical Outcomes in Freezing-all Embryo Transfer Program

引用

Current Medical Science 2018年第5期38卷 861-867页

作者： Xiao-lan LI Rui HUANG cong fang Xiao-yan LIANG Reproductive Medicine Research Center Sixth Affiliated HospitalSun Yat-sen UniversityGuangzhou 510655China

As a novel biomarker,there is inconsistent evidence regarding the association between anti-Miillerian hormone (AMH) and live birth rate in freezing-all embryo transfer cycles.We aim to assess the prognostic effect of baseline AMH on clinical outcomes,especially live birth rate in freezing-all embryo transfer cycles.A total of 828 non-polycystic ovary patients that underwent their first frozen-thawed embryo transfers in our center between January 2010 and January 2015 were recruited in this retrospective analysis.Patients were stratified into three groups based on their baseline AMH concentration:low AMH group (5.8 ng/mL).The results showed that low AMH level was associated With adverse clinical outcomes.The differences in implantation rate (21.9% vs.43.2% vs.58.8%,P<0.001),clinical pregnancy rate (32.0% vs.55.2% vs.65.7%, P<0.001),live birth delivery rate (21.8% vs.43.6% vs.52.7%,P<0.001)and miscarriage rate (31.8% vs.17.5% vs.15.4%,P=0.014)among the three groups were statistically significant.After adjusting confounders (i.***.age,baseline FSH level,AFC,endometrium thickness,endometriurn preparation protocols,number of embryos transferred,etiologies of infertility),differences in live birth rate,clinical pregnancy rate and implantation rate between groups remained significant.The further age subgroup analysis demonstrated that low AMH concentration was significantly associated with poor outcomes both in young and advanced patients.The area under the curve for serum AMH,age,AFC and FSH were 0.635,0.634,0.615 and 0.543 respectively,for predicting live birth.In conclusion, baseline AMH was an independent prognostic factor of live birth rate of freezing-all embryo transfers,but its predictive value on live birth rate was of limited clinical value.

关键词： anti-Miillerian hormone freezing-all embryo transfer live birth rate

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Effects of MⅡ stage oocytes zona pellucida birefringence on pregnancy outcome

引用

Asian Pacific Journal of Tropical Medicine 2013年第7期6卷 578-582页

作者： Jia Luo Yan-Wen Xu Ming-fang Zhang Ling Gao cong fang Can-Quan Zhou Reproductive Center of the First Affiliated Hospital of Sun Yat-sen University

Objective:To explore the effects of different MⅡstage oocytes zona pellucida birefringence on pregnancy outcome.Methods:A total of 46 couples with infertile which induced by single cause received in-vitro fertilization treatment were analyzed retrospectively,and randomly divided into the high zona birefringence(HZB)/HZB group.HZB/low zona birefringeuce(LZB) group and LZB/LZB group according to different oocytes zona pellucida birefringence.Intracytoplasmic sperm injection outcome was analyzed and compared.Results:The proportion of HZB oocytes, implantation rate and the pregnancy rate were decreased in three groups(HZB/HZB group>HZB/ LZB group>LZB/LZB group)(P0.05).Logistic regression analysis showed that factors allecl MⅡstage oocytes zona pellucida birefringence were age.basal FSH level and the LH level on the day of HCG injection.Age and KSH levels were negatively correlated with the single oocyte zona pellucida birefringence:While the LH level on the day of hCC injection was positively correlated with the single oocylc zona pellucida birefringence.Conclusions:The primary influence factors on MⅡstage oocytes zona pellucida are age.basal FSH level and the LH level on the day of hCG injection.The birefringence value of zona pellucida can affect the pregnancy outcome.

关键词： Oocytes Zona pellucida Intracytoplasmic sperm injection Implantation Pregnancy

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Logistic Regression Analysis of Risk Factors Associated with Spontaneous Abortion after In Vitro Fertilization/Intracytoplasmic Sperm Injection-Embryo Transfer in Polycystic Ovary Syndrome Patients

引用

Reproductive and Developmental Medicine 2018年第2期2卷 105-110页

作者： Xiao-Lan Li Rui Huang cong fang Yan-fang Wang Xiao-Yan Liang Reproductive Medicine Center The Sixth Affiliated Hospital of Sun Yat‑Sen UniversityGuangzhou 510655China

Objective:To analyze spontaneous abortion rate and its associated risk factors in patients with polycystic ovary syndrome(PCOS)after in vitro fertilization/intracytoplasmic sperm injection-embryo transfer(IVF/ICSI-ET).Methods:This was a retrospective cohort study on 2,231 PCOS patients undergoing IVF/ICSI treatment.For comparison,we enrolled another 2,231 patients with tubular factors in control group.Spontaneous abortion rate and chromosomal abnormality rate were compared between the two groups.Furthermore,clinical data were compared between the patients with spontaneous abortion and those with ongoing pregnancy using univariate and multivariate analysis for risk factors of spontaneous abortion in PCOS patients.Results:Patients in the PCOS group had significantly higher spontaneous abortion rate(24.15%)than that in the control group(12.75%,P<0.001).Chromosomal abnormality rate was significantly lower in the PCOS group(36.05%,31/86)than in the control group(55.56%,50/90,P=0.009).In the PCOS group,patients with spontaneous abortion had significantly elder age,higher body mass index(BMI),and homeostasis model assessment for insulin resistance(HOMA-IR)than those with ongoing pregnancy.The logistic regression analysis confirmed that the age,BMI,and HOMA-IR were the risk factors of spontaneous abortion in the PCOS patients.There were no significant differences between groups in the type of cycles,the quality of embryos transferred,the number of embryos transferred,fasting blood glucose,fasting insulin,and so on.Conclusions:Compared with non-PCOS patients,PCOS patients had higher spontaneous abortion rate,but the chromosomal abnormality was not a major factor for the high spontaneous abortion rate in the PCOS patients.Age,BMI,and HOMA-IR were risk factors for spontaneous abortion after IVF/ICSI-ET in PCOS patients.

关键词： Polycystic Ovary Syndrome Risk Factors Spontaneous Abortion

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

The Clinical Outcomes of Mosaic Embryo Transfer in Preimplantation Genetic Testing Cycles

引用

Advances in Sexual Medicine 2023年第2期13卷 11-20页

作者： Shujing He Linan Xu Huiling Pan Kuan Cheng Zhiqiang Zhang cong fang Zi Ren Reproductive Medicine Research Center The Sixth Affiliated Hospital Sun Yat-sen University Guangzhou China Biomedical Innovation Center The Sixth Affiliated Hospital Sun Yat-sen University Guangzhou China Guangdong Engineering Technology Research Center of Fertility Preservation Guangzhou China

Purpose: We aimed to analyze the pregnancy outcomes and perinatal follow-up of mosaic embryo transfer in the preimplantation genetic testing (PGT) cycles. Method: We retrospectively selected 27 mosaic embryo transfer cycles as the study group and 97 euploid embryo transfer cycles as the control group after propensity score matching, which were performed in the reproductive medicine center of the Sixth Affiliated Hospital, Sun Yat-sen University, from March 2019 to September 2023. The biopsy cells from blastocyst were undertaken next generation sequencing (NGS). Results: No significant difference in pregnancy outcomes compared between the two groups. According to the size of aneuploid, fragment the level of mosaicism or blastocyst morphological gradings, there were no significant difference in mosaic embryo transfers. Conclusion: Mosaic embryo detected in the PGT cycle can lead to clinical pregnancy and live birth of healthy offspring, which can be considerate suitable for transfer.

关键词： Mosaic Embryo PGT Pregnancy Outcomes Perinatal Follow-Up

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

A mumps model with seasonality in China

引用

Infectious Disease Modelling 2017年第1期2卷 1-11页

作者： Qianqian Qu cong fang Le Zhang Wanru Jia Jie Weng Yong Li School of Information and Mathematics Yangtze UniversityJingzhou 434023China School of Mechanical Engineering Yangtze UniversityJingzhou 434023China Institute of Applied Mathematics Yangtze UniversityJingzhou 434023China

Background:Mumps,an infectious viral disease,classically manifested by inflammation of salivary glands and is best known as a common childhood viral disease with no specific treatment.Although it can be protected by vaccine,there are more than 100,000 reported mumps cases according to the Chinese Center for Disease Control and Prevention.However,the factors and mechanisms behind the persistence and prevalence of mumps have not been well understood.Methods:A mumps model with seasonal fluctuation is formulated and investigated.We evaluate the basic reproduction numberℛ0 and analyze the dynamical behavior of the model.We also use the model to simulate the monthly data of mumps cases and carry out some sensitivity analysis ofℛ0 in terms of various model parameters.Results:It is shown that there exists only disease-free solution which is globally asymptotically stable ifℛ01.ℛ0 is a threshold parameter,and its magnitude determines the extinction or persistence of the disease.Conclusion:Our analysis shows that vaccination rate and invalid vaccination rate play important roles in the spread of mumps.Hence,Our study suggests to increase the vaccine coverage and make two doses of MMR(Measles,mumps and rubella vaccine)vaccine freely available in China.

关键词： Mumps Basic reproduction number Periodic solution Vaccination

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Analysis of reflected signal of quad rotor UAV based on model fitting in mobile communication system

引用

Journal of Systems Engineering and Electronics 2022年第1期33卷 97-104页

作者： LI Xiaohui fang cong FAN Tao School of Telecommunication Engineering Xidian UniversityXi’an 710071China Guangzhou Institute of Technology Xidian UniversityGuangzhou 510555China

In view of the many scenes of unmanned aerial vehicle(UAV)detection,a third-party signal source is used to design a receiver to monitor the UAV.It is of great significance to understand the reflection of the signal illuminating the UAV.Taking the communication base station(BS)signal as the third-party signal source,and considering the complete transmission link,reflection changes and loss fading of the communication signal,this study conducts model fitting for irregular UAV targets,simplifying complex targets into a combination of simple targets.Furthermore,the influence of the dielectric constant of the target surface and the signal irradiation angle on the signal reflection is analyzed.The analysis shows that the simulation results of this model fitting method are consistent with the results of other literature,which provides theoretical support for the detection of low and slow small targets such as UAVs.

关键词： mobile communication signal quad rotor unmanned aerial vehicle(UAV) signal reflection model fitting

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：