4 research outputs found
2-(1-(Arylimino)ethyl)-8-arylimino-5,6,7-trihydroquinolylcobalt dichloride: Synthesis and polyethylene wax formation
A series of 2-(1-(arylimino)ethyl)-8-arylimino-5,6,7-trihydroquinolylcobalt dichloride (aryl = 2,6-R1-4-R2C6H2) pre-catalysts were synthesized and structurally characterized by FT-IR and elemental analyses. The molecular structures of Co1 (R1 = Me, R 2 = H), Co2 (R1 = Et, R2 = H) and Co5 (R 1 = Et, R2 = Me) were determined by single-crystal X-ray diffraction analysis, and confirmed Co1 as a distorted trigonal bipyramidal geometry at the metal, whilst in Co2 and Co5 the metal is square-pyramidal. Upon treatment with either MAO or MMAO, all cobalt pre-catalysts exhibited highest activities at 60 °C for ethylene polymerization. The resultant polyethylenes, under optimization reaction parameters, possessed low molecular weight (waxes) and narrow polydispersity. © 2012 Elsevier B.V
Collagen–Hyaluronic Acid Composite Hydrogels with Applications for Chronic Diabetic Wound Repair
Chronic diabetic wounds have become a major healthcare
challenge
worldwide. Improper treatment may lead to serious complications. Current
treatment methods including biological and physical methods and skin
grafting have limitations and disadvantages, such as poor efficacy,
inconvenience of use, and high cost. Therefore, developing a more
effective and feasible treatment is of great significance for the
repair of chronic diabetic wounds. Hydrogels can be designed to serve
multiple functions to promote the repair of chronic diabetic wounds.
Furthermore, 3D bioprinting enables hydrogel customization to fit
chronic diabetic wounds, thus facilitating the healing process. This
paper reports a study of 3D printing of a collagen–hyaluronic
acid composite hydrogels with application for chronic diabetic wound
repair. In situ printed hydrogels were developed by a macromolecular
crosslinking network using methacrylated recombinant human collagen
(RHCMA) and methacrylated hyaluronic acid (HAMA), both of which can
respond to ultraviolet (UV) irradiation. The hydrogels were also loaded
with silver nanoclusters (AgNCs) with ultra-small-size nanoparticles,
which have the advantages of deep penetration ability and broad-spectrum
high-efficiency antibacterial properties. The results of this study
show that the developed RHCMA, HAMA, and AgNCs (RHAg) composite hydrogels
present good UV responsiveness, porosity, mechanical properties, printability,
and biocompatibility, all of which are beneficial to wound healing.
The results of this study further show that the developed RHAg hydrogels
not only effectively inhibited Staphylococcus aureus and Pseudomonas aeruginosa but also
promoted the proliferation and migration of fibroblasts in vitro and
tissue regeneration and collagen deposition in vivo, thus producing
a desirable wound repair effect and can be used as an effective functional
biomaterial to promote chronic diabetic wound repair
Enhancing the Activity and Thermal Stability of Nickel Complex Precatalysts Using 1‑[2,6-Bis(bis(4-fluorophenyl)methyl)-4-methyl phenylimino]-2-aryliminoacenaphthylene Derivatives
The
series of acenaphthylene-1-[2,6-bisÂ(bisÂ(4-fluorophenyl)Âmethyl)-4-methylphenylimino]-2-arylimine
derivatives and their dichloronickel complexes were synthesized and
fully characterized as well as the single-crystal X-ray diffraction
of representative nickel complexes, revealing a distorted tetrahedral
geometry. Upon activation with either MAO or Et<sub>2</sub>AlCl, all
nickel complexes showed high activities in ethylene polymerization;
moreover, their catalytic systems showed better thermal stabilities
on being manipulated at 80 °C as the industrial operating temperature