Effects of tin phosphate nanosheet addition on proton-conducting properties of sulfonated poly(ether sulfone) membranes

Organic/inorganic composite membranes were prepared by dispersing nanosheets of layered tin phosphate hydrate [Sn(HPO4)2·nH2O (SnP)] in sulfonated poly(ether sulfone) (SPES) at SnP contents of 0–40 vol.%. The stabilities and proton conductivities of SPES/SnP nanosheet (SnP-NS) composite membraneswere investigated and comparedwith those of SPES/SnP particle (SnP-P) composite membranes. The chemical stabilities as evaluated by thermogravimetry, differential thermal analysis, and diffuse reflectance Fourier-transform infrared spectroscopy were improved in both composite membranes. The improvement in the structural stability of SPES/SnP-NS composite membranes was more evident than that in SPES/SnP-P. The results suggest that exfoliation of SnP increases the area of the SPES–SnP interface and extends the connectivity of the network of hydrogen bonds. A composite membrane containing 10 vol.% SnP-NS (SPES/SnP-NS10vol.%) showed a high conductivity of 5.9×10−2 S cm−1 at 150 °C under saturated water vapor pressure. Although less water was present in SPES/SnP-NS10vol.% than in SPES/SnP-P10vol.% or pure SPES, the conductivity of SnP-NS10vol.% was the highest among these samples at 130 °C under a high relative humidity (RH). However at a low RH, the proton-conducting property was not improved by changing the composition of the SnP-NS. These results suggest that the hydrogen-bond network operates effectively for proton conduction at a high RH, but at a low RH, the network fails to conduct as a result of a decrease in water content accompanied by structural stabilization

Sulfonated polyether ether ketone-based composite membranes doped with a tungsten-based inorganic proton conductor for fuel cell applications

Sulfonated polyether ether ketone (SPEEK)-based composite membranes doped with hydrated tungsten oxide were prepared and studied for proton exchange membrane applications. Hydrated tungsten oxide (W O3 ·2 H2 O) was synthesized via acidic hydrolysis of sodium tungstate and its structure and physicochemical features were investigated by thermogravimetric analysis (TG), X-ray diffraction (XRD), and electrochemical impedance spectroscopy (EIS). SPEEK/ W O3 ·2 H2 O composite membranes were prepared by mixing proper amounts of SPEEK and hydrated W O3 in dimethylacetamide as casting solvent. The composite membranes were characterized by XRD, TG-DTA, EIS, and water uptake measurements as a function of the oxide content in the membrane. In particular, XRD patterns as well as TG measurements indicated the existence of a coordinative interaction between the water molecules of tungsten oxide and the SPEEK sulfonic acid groups. This interaction lead to the enhancement of the membrane proton conductivity, as well as of their properties, from the point of view of heat resistance and water solubility. In fact, the addition of tungsten oxide resulted in higher proton conductivity, improved heat resistance, and lower water solubility. © 2006 The Electrochemical Society. All rights reserved

3D ToF-SIMS imaging of polymer multilayer films using argon cluster sputter depth profiling

ToF-SIMS imaging with argon cluster sputter depth profiling has provided detailed insight into the three-dimensional (3D) chemical composition of a series of polymer multilayer structures. Depths of more than 15 μm were profiled in these samples while maintaining uniform sputter rates. The 3D chemical images provide information regarding the structure of the multilayer systems that could be used to inform future systems manufacturing and development. This also includes measuring the layer homogeneity, thickness, and interface widths. The systems analyzed were spin-cast multilayers comprising alternating polystyrene (PS) and polyvinylpyrrolidone (PVP) layers. These included samples where the PVP and PS layer thickness values were kept constant throughout and samples where the layer thickness was varied as a function of depth in the multilayer. The depth profile data obtained was observed to be superior to that obtained for the same materials using alternative ion sources such as C60 n+. The data closely reflected the “as manufactured” sample specification, exhibiting good agreement with ellipsometry measurements of layer thickness, while also maintaining secondary ion intensities throughout the profiling regime. The unprecedented quality of the data allowed a detailed analysis of the chemical structure of these systems, revealing some minor imperfections within the polymer layers and demonstrating the enhanced capabilities of the argon cluster depth profiling technique

Hepatocelluar nodules in liver cirrhosis: hemodynamic evaluation (angiography-assisted CT) with special reference to multi-step hepatocarcinogenesis

To understand the hemodynamics of hepatocellular carcinoma (HCC) is important for the precise imaging diagnosis and treatment, because there is an intense correlation between their hemodynamics and pathophysiology. Angiogenesis such as sinusoidal capillarization and unpaired arteries shows gradual increase during multi-step hepatocarcinogenesis from high-grade dysplastic nodule to classic hypervascular HCC. In accordance with this angiogenesis, the intranodular portal supply is decreased, whereas the intranodular arterial supply is first decreased during the early stage of hepatocarcinogenesis and then increased in parallel with increasing grade of malignancy of the nodules. On the other hand, the main drainage vessels of hepatocellular nodules change from hepatic veins to hepatic sinusoids and then to portal veins during multi-step hepatocarcinogenesis, mainly due to disappearance of the hepatic veins from the nodules. Therefore, in early HCC, no perinodular corona enhancement is seen on portal to equilibrium phase CT, but it is definite in hypervascular classical HCC. Corona enhancement is thicker in encapsulated HCC and thin in HCC without pseudocapsule. To understand these hemodynamic changes during multi-step hepatocarcinogenesis is important, especially for early diagnosis and treatment of HCCs

COMMD1-Mediated Ubiquitination Regulates CFTR Trafficking

The CFTR (cystic fibrosis transmembrane conductance regulator) protein is a large polytopic protein whose biogenesis is inefficient. To better understand the regulation of CFTR processing and trafficking, we conducted a genetic screen that identified COMMD1 as a new CFTR partner. COMMD1 is a protein associated with multiple cellular pathways, including the regulation of hepatic copper excretion, sodium uptake through interaction with ENaC (epithelial sodium channel) and NF-kappaB signaling. In this study, we show that COMMD1 interacts with CFTR in cells expressing both proteins endogenously. This interaction promotes CFTR cell surface expression as assessed by biotinylation experiments in heterologously expressing cells through regulation of CFTR ubiquitination. In summary, our data demonstrate that CFTR is protected from ubiquitination by COMMD1, which sustains CFTR expression at the plasma membrane. Thus, increasing COMMD1 expression may provide an approach to simultaneously inhibit ENaC absorption and enhance CFTR trafficking, two major issues in cystic fibrosis

Prophylactic Embolization of the Cystic Artery Before Radioembolization: Feasibility, Safety, and Outcomes

PurposeTo evaluate the safety and efficacy of two different methods of proximal cystic artery embolization in patients undergoing yttrium-90 radioembolization.Materials and methodsForty-six patients had cystic artery embolization performed immediately before yttrium-90 radioembolization, either by using Gelfoam pledgets (n = 35) or coils (n = 11). Clinical symptomatology during the admission and angiographic findings at 1-month follow-up were retrospectively reviewed. Rates of collateralization or recanalization of the cystic artery were compared, as well as the frequency of postprocedural abdominal pain and need for cholecystectomy.ResultsTechnical success was achieved in all patients, and there were no procedural complications related to cystic artery embolization. Of the 11 coil-embolized patients, 5 (45%) demonstrated collateralization of the cystic artery at 1 month, and 1 (9%) demonstrated recanalization of the cystic artery. Of the 35 Gelfoam-embolized cases, 2 (6%) had collateralized at 1 month, and 14 (40%) had recanalized. Two patients (one from each group) had self-limited right upper quadrant pain after the procedure, and one patient in the coil embolization group required cholecystectomy.ConclusionProximal cystic artery embolization is safe and feasible and may be performed during liver-directed embolotherapy to minimize the exposure of the gallbladder to particulate, chemoembolic, or radioembolic agents