Publications by authors named "Bi Jiang"

6 Publications

  • Page 1 of 1

History of IUD utilization and the risk of preterm birth: a cohort study.

Arch Gynecol Obstet 2021 Jul 30. Epub 2021 Jul 30.

Dongguan Maternal and Child Health Care Hospital, No.99 Zhenxing Road, Dongcheng District, Dongguan City, 523112, Guangdong Province, China.

Objective: To explore whether a history of IUD use could increase the risk of subsequent preterm birth.

Methods: We performed a cohort study of 24,496 multipara aged 19-48 years in Dongguan City. Each subject was followed up for 1 year, and 12,508 women obtained pregnancy outcomes. They were divided into 2 groups: 2130 subjects with IUD use history (exposure group), and 10,378 subjects without IUD use history (control group). The exposure group will remove the IUD before pregnancy. The primary outcomes were preterm birth (less than 37 weeks of gestation) and early preterm birth (less than 34 weeks of gestation). We used log-binomial regression to estimate adjusted risk ratios (aRR) of preterm birth and early preterm birth for women with a history of IUD. According to the different adjusted baseline data, three regression models were established, and the propensity matching score method was also used to verify the stability of the results.

Results: The delivery rate of women with IUD history was 51.24%, and that of women without IUD was 51.03% ( = 0.063, P = 0.802). Six hundred and eighty-five women had preterm birth (5.48%, 95% CI 5.08-5.88) and 133 women had early preterm birth (1.06%, 95% CI 0.83-1.24). Compared with the control group, the incidence of preterm birth and early preterm birth in the exposure group were significantly lower. The results are stable in all four models. Subgroup analysis also supported the result. This study also found that the longer the women used IUD before pregnancy, the younger the age of first using IUD, and the shorter the time from condom removal to pregnancy, the lower the incidence of premature birth.

Conclusion: The women with a history of IUD use are less likely to have premature birth after the IUD is removed. More prospective studies are needed to confirm it.
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http://dx.doi.org/10.1007/s00404-021-06158-9DOI Listing
July 2021

Effect of Laser Beam Oscillation on Laser Welding-Brazing of Ti/Al Dissimilar Metals.

Materials (Basel) 2019 Dec 11;12(24). Epub 2019 Dec 11.

State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China.

Ti4Al6V and 6061 Al dissimilar metals were butt welded by the laser oscillating welding method. The effects of laser offset, oscillation frequency, and energy distribution on the formation, microstructure, and tensile properties of dissimilar metal joints are discussed in detail. The experimental results show that the Ti6Al4V was micro melted with a laser offset of 1.1 mm, and a large number of intermetallic compounds (IMCs) were formed on the side of the Ti6Al4V. Additionally, there were some porosity defects in the fusion zone (FZ) due to an inappropriate laser oscillation frequency. When the laser offset was increased to 1.2 mm, the IMC distribution was uniform and the thickness was controlled below 2 μm. The porosity defects in the FZ decreased and the tensile strength of the joints increased significantly. The maximum value of tensile strength reached 173 MPa at a laser frequency of 28 Hz.
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http://dx.doi.org/10.3390/ma12244165DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6947189PMC
December 2019

Microstructure and Mechanical Properties of Laser Welded Al-Si Coated Hot-Press-Forming Steel Joints.

Materials (Basel) 2019 Oct 11;12(20). Epub 2019 Oct 11.

State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China.

High strength steel has attracted a lot of attention due to its excellent advantage of weight reduction. A thin Al-Si coating covered on the surface of hot-press-forming (HPF) steel offers functions of antioxidation and decarburization under high temperature processing conditions. In this study, the microstructure characteristic, phase, microhardness, and tensile strength of laser welded Al-Si coated HPF steel joints were investigated at different laser powers. Experimental results show that the welding process becomes unstable because of metallic vapor generated by ablation of the coating. Some of the white bright rippled Fe-Al phase was observed to be distributed in the fusion zone randomly. It is found that microhardness, tensile strength, and cupping test qualification rate decreases with the increase of the laser power. For the 1.1 kW laser power, the sound weld performs the best mechanical properties: Microhardness of 466.53 HV and tensile strength of 1349.9 MPa.
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http://dx.doi.org/10.3390/ma12203294DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6829890PMC
October 2019

The effects of preconception examinations on birth defects: a population-based cohort study in Dongguan City, China.

J Matern Fetal Neonatal Med 2020 Aug 7;33(16):2691-2696. Epub 2019 Jan 7.

Dongguan Maternal and Child Health Care Hospital, Dongguan, China.

To evaluate the effect of preconception examinations programs on the prevention of birth defects in Dongguan City during 2013-2017. The data were from preconception examinations system and the birth defects surveillance system during 2013-2017. The study population included 63,175 infants born to mothers accepted preconception examinations during pregnancy (the screening group) and 649,862 infants whose mother did not check (the control group). The infants included for stillbirth, dead fetus, live birth between 28 weeks of gestation and 7 days after birth and legal pregnancy termination. The risk ratios (RRs) and 95% confidence intervals (CIs) were calculated to examine for the association between birth defects and preconception examinations. We also conducted a stratified analysis based on infant gender and disease classification, and maternal age and region. The incidence of birth defects in the screening group was 134.55/10,000, while that in the control group was 241.53/10,000. Preconception examinations can effectively reduce the incidence of birth defects (BDs) (RR: 0.557, 95%CI: 0.520-0.597). Bifid spine (RR: 0.076, 95%CI: 0.011-0.545), anencephalia (RR: 0.134, 95%CI: 0.033-0.543) and anorectal atresia or stenosis (RR: 0.151, 95%CI: 0.048-0.471) were controlled best, and Down syndrome (RR: 0.684, 95%CI: 0.435-1.075) was no effect. Young maternal age (14-19 years) and old maternal age will increase the risk of birth defects. Preconception examinations had the best effect for pregnant women under 25 years of age (RR: 0.465, 95%CI: 0.387-0.559), and were relatively poor for women aged 30-34 years (RR: 0.678, 95%CI: 0.593-0.776). The incidence of the urban was significantly higher than that of the rural. The effect of preconception examinations to prevent birth defects was more effective in urban areas (RR: 0.453, 95%CI: 0.391-0.525) than in rural areas (RR: 0.577, 95%CI: 0.533-0.625). The incidence of BDs in males was higher than that in females. By implementing preconception examinations project, birth defects in Dongguan have been well controlled. This can provide reference for other developing countries to prevent birth defects.
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http://dx.doi.org/10.1080/14767058.2018.1557141DOI Listing
August 2020

Mechanistic investigations of the iridium(III)-catalyzed aerobic oxidation of primary and secondary alcohols.

J Am Chem Soc 2008 Nov 9;130(44):14462-4. Epub 2008 Oct 9.

Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, North Carolina 27695-8204, USA.

The commercially available catalysts [(Cp*IrCl2)2] is employed with O2 as the terminal oxidant in the presence of catalytic amounts of Et3N for the aerobic oxidation of primary and secondary alcohols. A new mechanism for the Ir-catalyzed aerobic oxidation is also presented that suggests that the transition metal maintains its +3 oxidation state throughout the entire catalytic cycle.
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http://dx.doi.org/10.1021/ja8049595DOI Listing
November 2008

Nanosized rigid pi-conjugated molecular heterojunctions with multi[60]fullerenes: facile synthesis and photophysical properties.

J Org Chem 2006 Jun;71(12):4400-10

Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.

A series of large, rigid, new, well-defined, D-pi-B-A compounds with three chromophores (truxene moieties at the core, conjugated oligothiophenes as the branch bridges, and [60]pyrrolidinofullerene (C60) segments as the end-capped groups) have been facilely developed in this contribution. Oligothiophene-functionalized truxene derivatives 1-29 are prepared by the Suzuki, the Sonogashira, and the Negishi cross-coupling reactions catalyzed by Pd(PPh3)4 as well as the McMurry reaction, respectively. The 1,3-dipolar cycloaddition of the oligomers with C60 and N-methylglycine yields a new family of star-shaped D-pi-B-A derivatives end-capped with pyrrolidinofullerene moieties as the active materials for photovoltaic devices in which one, two, three, or four C60 moieties are allocated at the peripheral position of well-defined compounds, respectively. We also investigate the UV-vis and photoluminescence behaviors of these pyrrolidinofullerene-functionalized derivatives. The emission is obviously quenched after the inducement of the C60 moieties. We also observe that the emission intensity is decreased with the increase in the number of C60 moieties.
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http://dx.doi.org/10.1021/jo060097tDOI Listing
June 2006
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