Shedding light on the elusive role of endothelial cells in cytomegalovirus dissemination.

Cytomegalovirus (CMV) is frequently transmitted by solid organ transplantation and is associated with graft failure. By forming the boundary between circulation and organ parenchyma, endothelial cells (EC) are suited for bidirectional virus spread from and to the transplant. We applied Cre/loxP-mediated green-fluorescence-tagging of EC-derived murine CMV (MCMV) to quantify the role of infected EC in transplantation-associated CMV dissemination in the mouse model. Both EC- and non-EC-derived virus originating from infected Tie2-cre(+) heart and kidney transplants were readily transmitted to MCMV-naïve recipients by primary viremia. In contrast, when a Tie2-cre(+) transplant was infected by primary viremia in an infected recipient, the recombined EC-derived virus poorly spread to recipient tissues. Similarly, in reverse direction, EC-derived virus from infected Tie2-cre(+) recipient tissues poorly spread to the transplant. These data contradict any privileged role of EC in CMV dissemination and challenge an indiscriminate applicability of the primary and secondary viremia concept of virus dissemination

Vital Rates from the Action of Mutation Accumulation

New models for evolutionary processes of mutation accumulation allow hypotheses about the age-specificity of mutational effects to be translated into predictions of heterogeneous population hazard functions. We apply these models to questions in the biodemography of longevity, including proposed explanations of Gompertz hazards and mortality plateaus

New group 4 organometallic and imido compounds of diamide-diamine and related dianionic O2N2-donor ligands

New group 4 compounds supported by the tetradentate diamide-diamine ligand N2NN′ are reported (N2NN′ = (2-C 5H4N)CH2N(CH2CH 2NSiMe3)2) along with some comparative studies with the new bis(alkoxide)-diamine ligand O2NN′ (O 2NN′ = (2-C5H4N)CH2N(CH 2-CMe2O)2). Reaction of the previously described ZrCl2(N2NN′) (1) with 2 equiv of MeLi or PhCH2MgCl gave ZrR2(N2NN′) (R = Me (2) or CH2Ph (3)). Reaction of 1 with 1 equiv of RCH2MgCl gave the monoalkyl analogues ZrCl(R)(N2NN′) (R = CH2Ph (6) or CH2SiMe3 (7)). Reaction of Zr(CH2R) 4 (R = SiMe3 or CMe3) with H2N 2NN′ in C6D6 gave the corresponding Zr(CH2R)2(N2NN′), but these decomposed over several hours. Reaction of 1 with allylmagnesium chloride gave ZrCl{(2-NC5(6-C3H5)H4)CH 2N(CH2CH2NSiMe3)2}, in which the pyridyl group has undergone nucleophilic attack. Reaction of 2 with BArF3 (ArF = C6F5) in benzene led to the cyclometalated cation [Zr{(2-NC5H 4)CH2N(CH2CH2NSiMe 3)(CH2CH2NSiMe2CH 2-)}]+ via SiMe3 group C-H activation, but in the presence of THF the methyl cation [ZrMe-(THF)(N2NN′)] + was formed. Reaction of 6 with BAr3F gave the chloride cation [ZrCl(N2-NN′)]+. Reaction of Li2N2NN′ with Ti(NR)Cl2(py)3 gave the five-coordinate imides Ti(NR)(N2NN′) (R = tBu or Ar (15), Ar = 2,6-C6H3iPr2). Zirconium imides Zr(NAr)(N2NN′) and Zr(NtBu)-(py)(N2NN′) (18) were prepared by sequential reaction of 1 with LiCH2SiMe3 (2 equiv) and the appropriate amine and pyridine for the latter. Reaction of 1 with LiNH tBu (2 equiv) gave Zr(NHtBu)2(N 2NN′). Reaction of 18 with piperidine gave Zr(NH tBu)(NC5H10)(N2NN′) (19) via N-H bond activation. For comparative purposes the group 5 imides M(N tBu)Cl(N2NN′) (M = Nb (20) or Ta (21)) were prepared from Li2N2NN′ and the corresponding M(N t-Bu)Cl3(py)2. Reaction of 2- aminomethylpyridine with an excess of isobutylene oxide afforded H 2O2NN′ (22). Reaction of H2O 2NN′ (1 or 2 equiv) with Ti(NMe2)4 gave Ti(O2NN′)2, which reacted with TiCl 4(THF)2 to form TiCl2(O2NN′). Reaction of H2O2NN′ with Zr(CH2SiMe 3)2-Cl2(Et2O)2, Zr(NMe2)4, or Zr(CH2SiMe3) 4 gave ZrX2(O2NN′) (X = Cl, NMe 2, or CH2SiMe3 (27)). Reaction of 27 with BAr3F in the presence of THF formed [Zr(CH 2SiMe3)(THF)(O2NN′)]+, but in the absence of a Lewis base the μ-alkoxide-bridged dimer [Zr 2(CH2SiMe3)2(O2NN′) 2]2+ was formed. The compounds 3, 6, 15, 19, 21, 22, and 27 were crystallographically characterized. © 2005 American Chemical Society

Zirconium complexes of diamine-bis(phenolate) ligands: Synthesis, structures, and solution dynamics

A study was performed on the synthesis, structures and solution dynamics of zirconium complexes of diamine-bis(phenolate) ligands. A series of six- or eight-coordinate derivatives were prepared and crystallographically characterized. It was found that attempts to generate catalytically active systems for the polymerization of ethylene were unsuccessful, although THF-stabilized benzyl cations were identified

Design of Dye-Sensitized Solar triphenodioxazine using TiO2 as a semiconductor

The present work deals with the synthesis of multichromophores which strongly absorb the solar spectrum to functionalize the nanoparticle oxide semiconductor used in the hybrid cells. At first, we developed a material that forms a chromophore triphenodioxazine. We obtained some triphenodioxazines with high yields up to 70 percent. On the other hand, we have carried out many tests such as UV-Visible, Cyclic voltammetry for our molecules to check their electronic and optical properties. The results confirmed that these chromophores meet the criteria for use in photovoltaic cells. Finally, we have successfully realized photovoltaic cells with triphenodioxazine. The findings were very interesting since the photovoltaic conversion efficiencies ranged from 4.30% to 6.30%. The new synthesis strategy of these chromophores opens a way for the development of organic materials used for photovoltaics

New group 4 organometallic and imido compounds of diamide-diamine and related dianionic O2N2-donor ligands

New group 4 compounds supported by the tetradentate diamide-diamine ligand N2NN′ are reported (N2NN′ = (2-C 5H4N)CH2N(CH2CH 2NSiMe3)2) along with some comparative studies with the new bis(alkoxide)-diamine ligand O2NN′ (O 2NN′ = (2-C5H4N)CH2N(CH 2-CMe2O)2). Reaction of the previously described ZrCl2(N2NN′) (1) with 2 equiv of MeLi or PhCH2MgCl gave ZrR2(N2NN′) (R = Me (2) or CH2Ph (3)). Reaction of 1 with 1 equiv of RCH2MgCl gave the monoalkyl analogues ZrCl(R)(N2NN′) (R = CH2Ph (6) or CH2SiMe3 (7)). Reaction of Zr(CH2R) 4 (R = SiMe3 or CMe3) with H2N 2NN′ in C6D6 gave the corresponding Zr(CH2R)2(N2NN′), but these decomposed over several hours. Reaction of 1 with allylmagnesium chloride gave ZrCl{(2-NC5(6-C3H5)H4)CH 2N(CH2CH2NSiMe3)2}, in which the pyridyl group has undergone nucleophilic attack. Reaction of 2 with BArF3 (ArF = C6F5) in benzene led to the cyclometalated cation [Zr{(2-NC5H 4)CH2N(CH2CH2NSiMe 3)(CH2CH2NSiMe2CH 2-)}]+ via SiMe3 group C-H activation, but in the presence of THF the methyl cation [ZrMe-(THF)(N2NN′)] + was formed. Reaction of 6 with BAr3F gave the chloride cation [ZrCl(N2-NN′)]+. Reaction of Li2N2NN′ with Ti(NR)Cl2(py)3 gave the five-coordinate imides Ti(NR)(N2NN′) (R = tBu or Ar (15), Ar = 2,6-C6H3iPr2). Zirconium imides Zr(NAr)(N2NN′) and Zr(NtBu)-(py)(N2NN′) (18) were prepared by sequential reaction of 1 with LiCH2SiMe3 (2 equiv) and the appropriate amine and pyridine for the latter. Reaction of 1 with LiNH tBu (2 equiv) gave Zr(NHtBu)2(N 2NN′). Reaction of 18 with piperidine gave Zr(NH tBu)(NC5H10)(N2NN′) (19) via N-H bond activation. For comparative purposes the group 5 imides M(N tBu)Cl(N2NN′) (M = Nb (20) or Ta (21)) were prepared from Li2N2NN′ and the corresponding M(N t-Bu)Cl3(py)2. Reaction of 2- aminomethylpyridine with an excess of isobutylene oxide afforded H 2O2NN′ (22). Reaction of H2O 2NN′ (1 or 2 equiv) with Ti(NMe2)4 gave Ti(O2NN′)2, which reacted with TiCl 4(THF)2 to form TiCl2(O2NN′). Reaction of H2O2NN′ with Zr(CH2SiMe 3)2-Cl2(Et2O)2, Zr(NMe2)4, or Zr(CH2SiMe3) 4 gave ZrX2(O2NN′) (X = Cl, NMe 2, or CH2SiMe3 (27)). Reaction of 27 with BAr3F in the presence of THF formed [Zr(CH 2SiMe3)(THF)(O2NN′)]+, but in the absence of a Lewis base the μ-alkoxide-bridged dimer [Zr 2(CH2SiMe3)2(O2NN′) 2]2+ was formed. The compounds 3, 6, 15, 19, 21, 22, and 27 were crystallographically characterized. © 2005 American Chemical Society

A general route to alkylene-, arylene-, or benzylene-bridged ditin hexachlorides and hexaalkynides

The preparation of alkylene-, arylene-, or benzylene-bridged ditin hexachlorides in high yields from the reaction of the corresponding hexacyclohexylated compounds with tin tetrachloride is described. The tetragonal geometry of the tin atom of 1,4-bis(trichlorostannyl)-butane in the solid state indicates that no intramolecular or intermolecular interaction involving either end of the molecule exists in this compound. The ditin hexachlorides were successfully transformed in the corresponding hexaalkynides, precursors of hybrid materials

Pinning of the Fermi Level in CuFeO2 by Polaron Formation Limiting the Photovoltage for Photochemical Water Splitting

CuFeO2 is recognized as a potential photocathode for photo(electro)chemical water splitting. However, photocurrents with CuFeO2-based systems are rather low so far. In order to optimize charge carrier separation and water reduction kinetics, defined CuFeO2/Pt, CuFeO2/Ag, and CuFeO2/NiOx(OH)y heterostructures are made in this work through a photodeposition procedure based on a 2H CuFeO2 hexagonal nanoplatelet shaped powder. However, water splitting performance tests in a closed batch photoreactor show that these heterostructured powders exhibit limited water reduction efficiencies. To test whether Fermi level pinning intrinsically limits the water reduction capacity of CuFeO2, the Fermi level tunability in CuFeO2 is evaluated by creating CuFeO2/ITO and CuFeO2/H2O interfaces and analyzing the electronic and chemical properties of the interfaces through photoelectron spectroscopy. The results indicate that Fermi level pinning at the Fe3+/Fe2+ electron polaron formation level may intrinsically prohibit CuFeO2 from acquiring enough photovoltage to reach the water reduction potential. This result is complemented with density functional theory calculations as well. © 2020 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei