Hafnium and Zirconium Complexes Bearing SNN-Ligands Enhancing Catalytic Performances toward Ethylene/1-Octene Copolymerization

The development of efficient catalysts is an ongoing pursuit in the field of olefin polymerization in order to synthesize desired polyolefins and to advance the present polymerization processes. In this contribution, the synthesis and characterization of a class of Hf and Zr complexes bearing SNN-tridentate ligands were described. The Hf (Hf1 and Hf2) and Zr (Zr1 and Zr2) trimethyl complexes were synthesized by one-pot reactions of thio-imino-quinoline ligands with in situ formed MMe4 (M = Hf, Zr). Both NMR analysis and X-ray diffraction study suggest the formation of thio-amido-quinoline metal complexes via methyl migration from Hf (or Zr) to the carbon of imine. These Hf and Zr complexes exhibited high activity and excellent thermal stability toward ethylene/1-octene copolymerization and an activity as high as 2.57 × 106 g(PE)·mol–1(cat)·h–1 was obtained by Hf1 even at 150 °C. The resultant polymers had moderate to high molecular weights (6.1–41.3 × 104 g·mol–1) with very broad distributions (D̵ = 6.8–34.7). NMR study revealed that multiple active species were formed when Hf1 was activated by 1 equiv. of [Ph3C][B(C6F5)4]

Rare-Earth Metal Complexes Supported by A Tridentate Amidinate Ligand: Synthesis, Characterization, and Catalytic Comparison in Isoprene Polymerization

To systematically investigate the dependence of the initiating group and metal size on polymerization performance, a family of rare-earth metal bis(alkyl)/bis(benzyl)/bis(amide) complexes supported by a monoanionic tridentate amidinate ligand [(2,6-iPr2C6H3)NC(Ph)N(C6H4-2-OMe]− (HL) were synthesized and well-characterized. Treatment of rare-earth metal tris(alkyl)/tris(benzyl)/tris(amide) complexes Y(CH2C6H4NMe2-o)3 or Y(CH2SiMe3)3(THF)2 or Ln[N(SiHMe2)2]3(THF)x (Ln = Sc, x = 1; Ln = Y, La, Sm, Lu, x = 2) with 1 equiv of HL gave the corresponding mono(amidinate) rare-earth metal bis(alkyl)/bis(benzyl)/bis(amide) complexes [(2,6-iPr2C6H4)NC(Ph)N(C6H4-2-OMe)]Y(CH2C6H4NMe2-o)2 (1), [(2,6-iPr2C6H4)NC(Ph)N(C6H4-2-OMe)]Y(CH2SiMe3)2(THF) (2), and [(2,6-iPr2C6H4)NC(Ph)N(C6H4-2-OMe)]Ln[N(SiHMe2)2]2(THF)n (Ln = Y, n = 1 (3); Ln = La, n = 1 (4); Ln = Sc, n = 0 (5); Ln = Lu, n = 0 (6); Ln = Sm, n = 0 (7)) in good isolated yields. These complexes were characterized by elemental analysis, NMR spectroscopy, and single-crystal X-ray diffraction. In the presence of excess AlMe3 and on treatment with 1 equiv of [Ph3C][B(C6F5)4], these complexes could serve as precatalysts for cationic polymerization of isoprene, in which the dependence of the polymerization activity and regioselectivity on the initiating group and metal size was observed

Gelation of Vesicles and Nanoparticles Using Water-Soluble Hydrophobically Modified Chitosan

Hydrophobically modified chitosan (hmC) is a self-assembling polymer that has attracted recent attention for many applications, including as a hemostatic agent. One limitation with chitosan and its derivatives like hmC is that these polymers are soluble in water only under acidic conditions (because the pKa of chitosan is about 6.5), which could be undesirable for biomedical applications. To circumvent this limitation, we have synthesized a derivative of a C12-tailed hmC that is soluble in water at neutral pH. This water-soluble hmC (ws-hmC) is obtained by grafting O-carboxymethyl groups onto some of the primary hydroxyls on hmC. The solubility of ws-hmC at neutral pH is shown to be the result of a net anionic character for the polymer due to ionization of the carboxymethyl groups (in comparison, hmC is cationic). We also demonstrate that ws-hmC retains the self-assembling properties of hmC. Specifically, ws-hmC is able to induce gelation at neutral pH in dispersions of anionic surfactant vesicles as well as polymethylmethacrylate latex nanoparticles. Gelation is attributed to hydrophobic interactions between the hydrophobes on ws-hmC with vesicle bilayers and nanoparticle surfaces. In each case, gelation can be reversed by the addition of α-cyclodextrin, a supramolecule with a hydrophobic cavity that sequesters the hydrophobes on the polymer

Additional file 3 of Population structure analysis to explore genetic diversity and geographical distribution characteristics of wild tea plant in Guizhou Plateau

Additional file 3: Table S1. Sampling localities of 159 wild tea accessions

Plasmids used for host cell reactivation assays.

(A) pSF-tdTomato-END (for NHEJ, left) and pSF-tdTomato-HOM (for SSA, right) plasmids used for DSB repair assays. XhoI+ApaI double-digestion (= DSB) generated in vitro is repaired by either NHEJ or SSA after transfection in cells, thereby restoring EYFP expression. The common sequence between the two overlapping halves of EYFP in the SSA template (“YF” in grey) is 350bp long. Repair is measured by the percentage of EYFP+ cells among tdTomato+ cells. (B) pM1-Luc plasmid (left) and pRL-CMV (right) plasmids. Oxidative (8-oxoG) or UV damage (pyrimidine dimers) generated in vitro on pM1-Luc plasmid impairs expression of firefly luciferase (FL) that is then restored by BER or NER, respectively, once transfected in cells. Repair is measured by the FL activity after normalization to renilla luciferase (RL) activity (transfection control) and in comparison to the undamaged FL template (100% expression) in the same cells.</p

Additional file 2 of Population structure analysis to explore genetic diversity and geographical distribution characteristics of wild tea plant in Guizhou Plateau

Additional file 2: Figure S1. Geographic distribution of 159 materials collected at different altitudes and rock types. Note: (A) Geographical position. (B) Distribution map of altitude, rock type and sample point in Guizhou Plateau. Figure S2. Graph for CV error in the range of K=1-9 of 159 wild tea accessions. Figure S3. ML tree of four geologically suitable areas. Note: I Dolomite sub-suitable area, II Dolomitic limestone suitable area, III Clastic rock most suitable area, IV Purple clastic rock suitable area

Additional file 1 of Population structure analysis to explore genetic diversity and geographical distribution characteristics of wild tea plant in Guizhou Plateau

Additional file 1: Table S1. Information of 159 wild tea accessions used in this study. Table S2. The quality control data of 159 wild tea accessions. Table S3. Statistics of Heterozygosity Rate of 98,241 SNPs in 159 wild tea accessions. Table S4. SNP density. Table S5. Statistics of the number and ratio of the accessions of species, rock classes and geologically suitable area in three inferred populations. Table S6. Statistics of the number and ratio of the accessions of altitude gradient in three inferred populations. Table S7. The soil nutrient content and altitude factor of 159 wild tea accessions

Terrace-Rich Ultrathin PtCu Surface on Earth-Abundant Metal for Oxygen Reduction Reaction

The activity and stability of the platinum electrode toward the oxygen reduction reaction are size-dependent. Although small nanoparticles have high Pt utilization, the undercoordinated Pt sites on their surface are assumed to have too strong oxygen binding strength, thus often leading to compromised activity and surface instability. Herein, we report an extended nanostructured PtCu ultrathin surface to reduce the number of low-coordination sites without sacrificing the electrochemical active surface area (ECSA). The surface shows (111)-oriented characteristics, as proven by electrochemical probe reactions and spectroscopies. The PtCu surface brings over an order of magnitude increase in specific activity relative to commercial Pt/C and nearly 4-fold enhancement in ECSA compared to traditional thin films. Moreover, due to the weak absorption of air impurities (e.g., SO2, NO, CO) on highly coordinated sites, the catalyst displays enhanced contaminant tolerance compared with nanoparticulate Pt/C. This work promises a broad screening of extended nanostructured surface catalysts for electrochemical conversions

Association between the Polymorphisms in Intercellular Adhesion Molecule-1 and the Risk of Coronary Atherosclerosis: A Case-Controlled Study

<div><p>Intercellular adhesion molecule-1 (ICAM-1), an important immune adhesion molecule, is related to the atherosclerosis. We explored the association between the polymorphisms of the ICAM-1 gene and coronary atherosclerotic stenosis to determine whether any risk factors correlate with genetic polymorphisms in Chinese patients with coronary atherosclerosis. Using the SNaPshot assay, we examined six SNPs of rs5491, rs281428, rs281432, rs5496, rs5498 and rs281437 in 604 patients diagnosed with coronary atherosclerotic stenosis by angiography and in 468 controls. We found that AG genotype of rs5498 had higher frequency in the coronary atherosclerotic stenosis patients (41.56% to 34.19%, P = 0.017, OR = 1.368,95%CI 1.057–1.770) and that the haplotype A_rs5491C_rs281428G_rs281432 had higher frequency in patients (13.8% to 12.1%, P = 0.048). When analyzing the clinical risk factors for coronary atherosclerosis, we found that the rs5498 locus was associated with the levels of apolipoprotein A (APOA) (P = 0.0002) and triglycerides (TG) (P = 0.002). Furthermore, the levels of triglycerides (TG) were also associated with rs281432 (P = 0.040). Additionally, the TT genotype of rs281437 was associated with a higher level of apolipoprotein A (APOA) (P = 0.039) and apolipoprotein B (APOB) (P = 0.003). Finally, among those with coronary atherosclerosis, we found no differences in the haplotype analysis of polymorphisms of the ICAM-1 gene from individuals with hypertension or those who smoked. According to our results, the ICAM-1 polymorphisms were associated with risk of coronary atherosclerotic stenosis in Chinese individuals.</p></div

DSB repair capacity in lymphocytes and LCLs of healthy individuals.

<p><b>(A)</b> NHEJ and <b>(B)</b> SSA repair in purified T cells of 2 healthy individuals either non-induced or induced to proliferate for 3 to 9 days <b>(C)</b> Correlation between SSA and NHEJ repair in non-induced unpurified lymphocytes (red triangles) and in 3–5 weeks old early LCLs (black circles). The linear regression trend lines with 95% confidence intervals are indicated, as well as the value of the slopes (a).</p