Wenxi Wang

In this study, we developed a pH-responsive shape-memory polymer nanocomposite by blending poly(ethylene glycol)-poly(ε-caprolactone)-based polyurethane (PECU) with functionalized cellulose nanocrystals (CNCs). CNCs were functionalized with pyridine moieties (CNC-C6H4NO2) through hydroxyl substitution of CNCs with pyridine-4-carbonyl chloride and with carboxyl groups (CNC-CO2H) via 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) mediated surface oxidation, respectively. At a high pH value, the CNC-C6H4NO2 had attractive interactions from the hydrogen bonding between pyridine groups and hydroxyl moieties; at a low pH value, the interactions reduced or disappeared due to the protonation of pyridine groups, which are a Lewis base. The CNC-CO2H responded to pH variation in an opposite manner. The hydrogen bonding interactions of both CNC-C6H4NO2 and CNC-CO2H can be readily disassociated by altering pH values, endowing the pH-responsiveness of CNCs. When these functionalized CNCs were added in PECU polymer matrix to form nanocomposite network which was confirmed with rheological measurements, the mechanical properties of PECU were not only obviously improved but also the pH-responsiveness of CNCs could be transferred to the nanocomposite network. The pH-sensitive CNC percolation network in polymer matrix served as the switch units of shape-memory polymers (SMPs). Furthermore, the modified CNC percolation network and polymer molecular chains also had strong hydrogen bonding interactions among hydroxyl, carboxyl, pyridine moieties, and isocyanate groups, which could be formed or destroyed through changing pH value. The shape memory function of the nanocomposite network was only dependent on the pH variation of the environment. Therefore, this pH-responsive shape-memory nancomposite could be potentially developed into a new smart polymer material.

In Brief Objective To evaluate the safety of donors who have donated the middle hepatic vein in right lobe live donor liver transplantation (LDLT) and to determine whether such inclusion is necessary for optimum graft function. Summary Background Data The necessity to include the middle hepatic vein in a right lobe graft in adult-to-adult LDLT is controversial. Inclusion of the middle hepatic vein in the graft provides uniform hepatic venous drainage but may lead to congestion of segment IV in the donor. Methods From 1996 to 2002, 93 right-lobe LDLTs were performed. All right-lobe grafts except 1 contained the middle hepatic vein. In the donor operation, attention was paid to preserve the segment IV hepatic artery and to avoid prolonged rotation of the right lobe. The middle hepatic vein was transected proximal to a major segment IVb hepatic vein whereas possible to preserve the venous drainage in the liver remnant. Results There was no donor death. Two donors had intraoperative complications (accidental left hepatic vein occlusion and portal vein thrombosis) and were well after immediate rectification. Twenty-four donors (26%) had postoperative complications, mostly minor wound infection. The postoperative international normalized ratio on day 1 was better in the donors with preservation of segment IVb hepatic vein than those without the preservation, but, in all donors, the liver function was largely normal by postoperative day 7. The first recipient had severe graft congestion as the middle hepatic vein was not reconstructed before reperfusion. In 7 other recipients, the middle hepatic vein was found occluded intraoperatively owing to technical errors. The postoperative hepatic and renal function of the recipients with an occluded or absent middle hepatic vein was worse than those with a patent middle hepatic vein. The hospital mortality rate was also higher in those with an occluded middle hepatic vein (3/9 vs. 5/84, P = 0.028). Conclusions Inclusion of the middle hepatic vein in right-lobe LDLT is safe and is essential for optimum graft function and patient survival. In 93 consecutive right lobe live-donor liver transplantations (LDLTs), the middle hepatic vein was included in all except one graft. There was no donor death. The liver function of the donors returned to nearly normal levels by postoperative day 7. After reperfusion, the graft showed congestion because the middle hepatic vein was not reconstructed (n = 1), not present (n = 1) or occluded (n = 7). The recipients with occluded or absent middle hepatic vein had worse postoperative hepatic and renal function than those with a patent middle hepatic vein. The hospital mortality rate was also higher.

The stabilization of black phosphorous quantum dots (BPQDs) for optical application under ambient conditions is highly challenging. Here, a facile approach is presented to substantially stabilize BPQDs by making a uniform BPQDs/polymethyl methacrylate (PMMA) composite nanofiber film via an electrospinning technique. As verified by femtosecond laser Z‐scan measurement, the BPQDs/PMMA composite nanofiber film that has been stored for three months exhibits almost the same nonlinear optical properties as the fresh BPQDs. Additionally, the BPQDs/PMMA composite nanofiber film demonstrates broadband nonlinear optical response ranging from the visible bandwidth (400 nm) to the mid‐IR bandwidth (at least 1930 nm). By employing the BPQDs/PMMA composite nanofiber film as an optical saturable absorber, an ultrashort pulse with the pulse duration of ≈1.07 ps centered at the wavelength of 1567.6 nm is generated in a mode‐locked fiber laser. These results suggest that the BPQDs/PMMA composite nanofiber film can combine the advantage of convenient integration and mitigation of the drawback of the easy oxidation of black phosphorous and pave the way for BP‐based practical optoelectronic devices.