Search

A pair of isomers, IDT‐BOF containing S⋅⋅⋅O/F⋅⋅⋅H noncovalently configurational locks and IDT‐BFO containing F⋅⋅⋅H/O⋅⋅⋅H noncovalently configurational locks, with an acceptor‐π‐donor‐π‐acceptor (A‐π‐D‐π‐A) structure have been designed and synthesized by choosing 4,9‐dihydro‐s‐indaceno[1,2‐b : 5,6‐b′]dithiophene (IDT) as the D unit, an F/n‐hexyloxy substituted phenyl ring as π bridge, and 3‐(dicyanomethylidene)indan‐1‐one as the A unit. Owing to the S⋅⋅⋅O/F⋅⋅⋅H or F⋅⋅⋅H/O⋅⋅⋅H noncovalently configurational locks, both IDT‐BOF and IDT‐BFO have a completely planar structure. IDT‐BOF exhibits a similar LUMO to IDT‐BFO, but higher HOMO energy levels, leading to a smaller optical bandgap and red‐shifted absorption. However, IDT‐BOF‐based bulk‐heterojunction organic solar cells (BHJ‐OSCs) coupled with PBDB‐T, and PCE‐10 as donor materials both exhibited a lower PCE than that of IDT‐BFO (PBDB‐T: 5.2 vs. 6.1 %; PCE‐10: 1.7 vs. 3.2 %). Comprehensively comparing and investigating IDT‐BOF : PBDB‐T and IDT‐BFO : PBDB‐T OSCs suggested that the large phase separation and serious charge recombination of IDT‐BOF‐based OSCs contributed to its lower power conversion efficiency. Importantly, ternary solar cells based on PBDB‐T : Y5 as control devices with an additional 10 % IDT‐BFO exhibited a 5 % enhancement in the PCE compared to the control device (14.3 vs. 13.46 %). [ABSTRACT FROM AUTHOR]

A high-melt-strength polypropylene (HMSPP) was prepared using a twin-screw reactive extruder from a commercial isotactic polypropylene through two stages, first, maleic anhydride is grafted to polypropylene to obtain a maleic anhydride-grafted polypropylene (PP-g-MA), and then the grafted polymer is reacted with epoxy to extend the branched chain. Fourier transformed infrared spectroscopy indicated that ma leic anhydride was grafted on polypropylene and reacted with epoxy. Melt flow rate and sag resistance test showed that the melt strength of the HMSPP improved considerably. Differential scanning calorimetry test showed that the long chain branches (LCBs) act as a nucleating agent in the crystallization of the HMSPP, which leads to a high crystallization temperature and crystallinity. Furthermore, the LCB efficiency of the HMSPP can also be calculated by analyzing its rheological property. POLYM. ENG. SCI., 48:1339-1344, 2008. (C) 2008 Society of Plastics Engineers, INTRODUCTION Isotactic polypropylene has many desirable and beneficial physical properties such as high mechanical strength, inertness to various chemical reagents, nontoxicity, high transparency, high glossiness, and so forth. However, as [...]

Abstract In this paper an improved mathematical model of a hydro-pneumatic tensioner (HPT) system for top tensioned riser (TTR) is derived by consideration of friction, mass of piston and piston rod, tension loss in hydraulic oil piping, and compressibility of hydraulic oil. The vertical motion of the riser string is also considered. Subsequently, the proposed detailed model and the conventional simplified model are comparatively studied. Finally, the tension characteristic and performance parameters of the HPT are analyzed based on the proposed model. Results show that the conventional simplified model indeed overestimates the tension of tensioner as it neglects some performance parameters resulting in tension loss. The diameters of piston and piston rod and the initial pressure of high pressure (HP) gas have the most significant influence on the tension of the tensioner. The initial volume of HP gas and the initial pressure of low pressure (LP) gas also have some impact. The influence of the initial volume of LP gas and the inner diameter and length of the piping is relatively small. The research has some reference value for HPT and TTR design. [ABSTRACT FROM AUTHOR]

Reactions of cobalt(II) nitrate or zinc(II) nitrate, tetrasodium p-sulfonatothiacalix[4]arene (Na4H4TCAS), and methylviologen dihexafluorophosphate (MV(PF6)2) afforded two isomorphous complexes, {[M(H2O)6]2 + [MV]2 + [(MV)2M2(H2O)4(H2TCAS)2]4 - }·14H2O (M = Co, 1; Zn, 2). In these two complexes, each two thiacalixarenes form a dimer with Ci symmetry through the coordination of sulfonate groups, and the above dimers further extend their structures through second-sphere coordination and π...π stacking interactions into three-dimension nets. [ABSTRACT FROM AUTHOR]

Abstract: The assembly of Ni(II) ions with linear spacers trans,trans-muconic acid (H2L) and 4,4′-bipyridine (4,4′-bpy) has afforded a compound, [Ni(L)(4,4′-bpy)(H2O)2] n (1). Single crystal X-ray diffraction analysis reveals that both 4,4′-bpy and deprotonated H2L act as linear bridges to bind square-planar Ni(II) nodes. Achiral ligands 4,4′-bpy induced in a chiral configuration link metal nodes into chiral chains, which are further bound into homochiral sheets by rigid L. Finally, a novel 3D chiral framework forms through three-fold slantwise interpenetration of those chiral (4,4) nets. The magnetic studies in the range 2–300K show that magnetic behavior of 1 possesses a large zero-field splitting of Ni(II) ions and an anti-ferromagnetic interaction between metal centers. [Copyright &y& Elsevier]

Biomass-derived acetic acid (HAc) is an alternative resource for hydrogen production, and heat self-sustained auto-thermal reforming (ATR) of HAc shows potential for practical application, while robust and stable catalysts remain as a key factor. Ca–Al layered double hydroxides (LDHs)-derived Ni-based catalysts were synthesized by co-precipitation, and tested in ATR of HAc for hydrogen production. Over the LDHs-derived Ca 2.55 Ni 0.45 AlO 4.5 catalyst, active sites of Ni–CaO–Ca 12 Al 14 O 33 were formed, and interaction among Ni, CaO and Ca 12 Al 14 O 33 was proved to be a pivotal role for 1) thermal stability, 2) resistance to oxidation of Ni0 species, and 3) inhibiting coke deposition through catalytic cycle, CaO + CO 2 ↔CaCO 3 and CaCO 3 +*C↔CaO+2CO, for gasification of coking precursors. Hence, the Ca 2.55 Ni 0.45 AlO 4.5 catalyst showed enhanced activity with no obvious deactivation in ATR: the acetic acid conversion rate was 100%, and the hydrogen yield remained stable near 2.75 mol-H 2 /mol-HAc at a rate of 40.34 mmol-H 2 /s/g-catalyst. Over the Ni–CaO–Ca 12 Al 14 O 33 active sites, the acetic acid conversion rate was 100%, and the hydrogen yield remained stable near 2.75 mol-H 2 /mol-HAc at a rate of 40.34 mmol-H 2 /s/g-catalyst during auto-thermal reforming of acetic acid. Image 1 • Auto-thermal reforming of acetic acid was used for hydrogen production. • Ca–Al LDHs with hydrocalumite was synthesized via co-precipitation. • Active sites of Ni–CaO–Ca 12 Al 14 O 33 produced H 2 at 40.34 mmol-H 2 /s/g-catalyst. • Coking precursors were gasified with CaO within active sites. • Sintering and oxidation were constrained within Ni–CaO–Ca 12 Al 14 O 33. [ABSTRACT FROM AUTHOR]

[Display omitted] Spin-delocalization and steric protection are commonly used and effective strategies to realize stable organic radicals. A bisheptamido-functionalized triarylamines derivative(T1) can enhance the stability of TPA photo-generated radical cations in air by supramolecular self-assembly and "push-pull" dipole structure to expand conjugation, so as to obtain air-stable solid free radicals with a lifetime of more than 60 days, which is based on the best record of the air-stabilized solid TPA radical cations. The preliminary studies demonstrate that T1 may be a promising candidate for organic semiconductor radical materials. [ABSTRACT FROM AUTHOR]