A review of pre-implantation genetic testing technologies and applications

The first practice of pre-implantation genetic testing(PGT)was reported more than 30 years ago.PGT,originally named preimplantation genetic screening(PGS)and pre-implantation genetic diagnosis(PGD),is now categorized as PGT for aneuploidies(PGT-A),PGT for monogenic/single-gene defects(PGT-M),and PGT for chromosomal structural rearrangements(PGT-SR).Patients with fertility issues caused by advanced maternal age,carrier status of chromosomal abnormalities,or harboring pathogenic variant(s)are recommended to undergo PGT to increase the possibility of successful live birth and avoid potentially affected newborns.High-throughput techniques,such as DNA microarrays and next-generation sequencing(NGS),have enabled comprehensive screening of all 24 chromosomes,instead of few loci at a time.Furthermore,as a comprehensive PGT,PGT-Plus was enabled by the rapid development of a genome-wide single-cell haplotyping technique to detect embryo aneuploidy,single-gene disorders,and chromosomal aberrations simultaneously using a single universal protocol.In addition,non-invasive approaches enable a more intact embryo during the biopsy procedure,which may avoid potential mosaicism issues at a certain scale by testing spent culture media(SCM).As a novel PGT application,PGT-P detects genome-wide variations in polygenic diseases,which account for a large proportion of premature human deaths and affect a markedly larger population than monogenic diseases,using polygenic risk score calculation to decrease the potential of affecting complex conditions.Owing to the emergence of new technologies recruited to PGTs,more couples with infertility issues have a promising chance of conceiving a healthy baby,ultimately facilitating the human species to live more prosper.

Thermostable α-Diimine Nickel Complexes with Substituents on Acenaphthequinone-backbone for Ethylene Polymerization

In order to promote the thermostability of a-diimine nickel complex by ligand backbone structure,a series of α-diimine nickel complexes with substituents on acenaphthequinone backbone were synthesized and used as catalysts for ethylene polymerization.When the hydroxyethyl phenoxyl group was introduced to the acenaphthequinone-backbone,the thermal stability and activity of the catalyst could be significantly improved.The catalytic activity of complex C2[5-(4-(2-hydroxyethyl)phenoxyl)-N,N-bis(2,6-diisopropyl)acenaphthylene-1,2-diimine]nickel(Ⅱ)dibromide with isopropyl substituents on N-aryl reached 8.2×10^6g/(molNi·h)at 70℃and 2 MPa.The activity of[5-(4-(2-hydroxyethyl)phenoxyl)-N,N-bis(2,6-dibenzhydryl-4-menthylphenyl)acenaphthylene-1,2-diimine]nickel(Ⅱ)dibromide(C3)still maintained at 6.7×10^5 g/(molNi·h)at 120℃.Compared with C3 containing bulky dibenzhydryl substituents,the activity of C2 was sensitive to the change of the polymerization pressure.However,the polyethylenes obtained from complex C3 had lower branching density.Meanwhile,the molecular weight could reach 971 kg/mol,which is almost 5 times as much as that of the polyethylene obtained from complex C2.

Linear/branched Block Polyethylene Produced by a-Diimine Nickel(Ⅱ)Catalyst and Bis(phenoxy-imine)Zirconium Binary Catalyst System in the Presence of Diethyl Zinc

In order to promote development of linear/branched block polyethylenes based on new catalytic systems,we synthesized a novel a.dimine nickel(Ⅱ)complex with isopropyl substituents on ortho-N-aryl and hydroxymethyl phenyl substituents on para-Naryl structures.The activity of a-dimine nickl(Ⅱ)catalyst was 3.02x10^(6)g-mol_(ni)^(-1)·h^(-1) at 70℃,and resultant polyethylene possessed 135/1000C branches.The linear/branched block polyethylenes were synthesized from ethylene polymerization catalyzed by the a-dimine nicke(Ⅱ)complex/bis(phenoxy-imine)zirconium in the presence of diethyI zinc.With the addition of ZnEtz(from 0 to 400),the melting peak of resultant polyethylene changed from a single melting peak to bimodal melting peaks.The molecular weights of resultant polyethylene ranging from 26.8 kg/mol to 17.1 kg/mol and PDI values varying gradually from 24.4 to 15.2 were obtained vla adjusting ZnEt;equiv.and molar ratio of two catalysts.In addition,the branching degree of the polyethylene increased from 13/1000C to 56/1000 with the increase of the proportion of a dimine nickel(Ⅱ)catalyst.Using this binary catalyst system,the reaction temperature of chain shutting polymerization can be carried out at 70℃,which is more conducive to industrial application.