Home About us Contact
|
Home About us Contact | ||
|
|
||
Hydrophilic Components (hydrophilic + component)
Selected AbstractsPartitioning of copper at concentrations below the marine water quality criteria,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2001Anthony J. Paulson Abstract Partitioning of Cu between the aqueous and particulate phases and among their components was examined in six ambient Puget Sound, Washington State, USA, samples (6,10 nM Cu). Most of the particulate Cu (4,12% of the total Cu) was associated with particulate organic matter, and resulted in distribution coefficients (Kd) ranging between 104,55 and 105,1. For the dissolved phase, the portion of Cu extracted by C18 -packed cartridges averaged 44% (+ 11%). Radioactive 64Cu was added to these samples to total stable Cu concentrations (17,33 nM). After 24 h of equilibration, the portion of 64Cu associated with the particulate matter in five of the six samples (Kd between 1047 and 1053) was an average of 70% higher than that of natural Cu in the ambient samples. In contrast, only 19 ± 7% of the 64Cu was extracted by C18 -packed cartridges. The partitioning of natural Cu and 64Cu onto particles was not significantly different when the equilibria were based on dissolved Cu passing through the C18 cartridges. Further research is warranted on utilizing the hydrophilic component of the dissolved phase as a parameter on which water quality criteria are based. [source] Synthesis and properties of novel sulfonated polyimides containing binaphthyl groups as proton-exchange membranes for fuel cellsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 2 2007Yuhan Li Abstract A novel sulfonated diamine monomer, 2,2,-bis(p -aminophenoxy)-1,1,-binaphthyl-6,6,-disulfonic acid (BNDADS), was synthesized. A series of sulfonated polyimide copolymers containing 30,80 mol % BNDADS as a hydrophilic component were prepared. The copolymers showed excellent solubility and good film-forming capability. Atomic force microscopy phase images clearly showed hydrophilic/hydrophobic microphase separation. The relationship between the proton conductivity and degree of sulfonation was examined. The sulfonated polyimide copolymer with 60 mol % BNDADS showed higher proton conductivity (0.0945,0.161 S/cm) at 20,80 °C in liquid water. The membranes exhibited methanol permeability from 9 × 10,8 to 5 × 10,7 cm2/s at 20 °C, which was much lower than that of Nafion (2 × 10,6cm2/s). The copolymers were thermally stable up to 300 °C. The sulfonated polyimide copolymers with 30,60 mol % BNDADS showed reasonable mechanical strength; for example, the maximum tensile strength at break of the sulfonated polyimide copolymer with 40 mol % BNDADS was 80.6 MPa under high moisture conditions. The optimum concentration of BNDADS was found to be 60 mol % from the viewpoint of proton conductivity, methanol permeability, and membrane stability. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 222,231, 2007 [source] Phase Segregation in Thin Films of Conjugated Polyrotaxane, Poly(ethylene oxide) Blends: A Scanning Force Microscopy Study,ADVANCED FUNCTIONAL MATERIALS, Issue 6 2007L. Sardone Abstract Scanning force microscopy (SFM) is used to study the surface morphology of spin-coated thin films of the ion-transport polymer poly(ethylene oxide) (PEO) blended with either cyclodextrin (CD)-threaded conjugated polyrotaxanes based on poly(4,4,-diphenylene-vinylene) (PDV), ,-CD,PDV, or their uninsulated PDV analogues. Both the polyrotaxanes and their blends with PEO are of interest as active materials in light-emitting devices. The SFM analysis of the blended films supported on mica and on indium tin oxide (ITO) reveals in both cases a morphology that reflects the substrate topography on the (sub-)micrometer scale and is characterized by an absence of the surface structure that is usually associated with phase segregation. This observation confirms a good miscibility of the two hydrophilic components, when deposited by using spin-coating, as suggested by the luminescence data on devices and thin films. Clear evidence of phase segregation is instead found when blending PEO with a new organic-soluble conjugated polymer such as a silylated poly(fluorene)- alt -poly(para -phenylene) based polyrotaxane (THS,,-CD,PF,PPP). The results obtained are relevant to the understanding of the factors influencing the interfacial and the intermolecular interactions with a view to optimizing the performance of light-emitting diodes, and light-emitting electrochemical cells based on supramolecularly engineered organic polymers. [source] Chemical modification of polyethersulfone nanofiltration membranes: A reviewJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2009B. Van der Bruggen Abstract Polysulfone (PS) and poly(ether)sulfone (PES) are often used for synthesis of nanofiltration membranes, due to their chemical, thermal, and mechanical stability. The disadvantage for applying PS/PES is their high hydrophobicity, which increases membrane fouling. To optimize the performance of PS/PES nanofiltration membranes, membranes can be modified. An increase in membrane hydrophilicity is a good method to improve membrane performance. This article reviews chemical (and physicochemical) modification methods applied to increase the hydrophilicity of PS/PES nanofiltration membranes. Modification of poly(ether)sulfone membranes in view of increasing hydrophilicity can be carried out in several ways. Physical or chemical membrane modification processes after formation of the membrane create more hydrophilic surfaces. Such modification processes are (1) graft polymerization that chemically attaches hydrophilic monomers to the membrane surface; (2) plasma treatment, that introduces different functional groups to the membrane surface; and (3) physical preadsorption of hydrophilic components to the membrane surface. Surfactant modification, self-assembly of hydrophilic nanoparticles and membrane nitrification are also such membrane modification processes. Another approach is based on modification of polymers before membrane formation. This bulk modification implies the modification of membrane materials before membrane synthesis of the incorporation of hydrophilic additives in the membrane matrix during membrane synthesis. Sulfonation, carboxylation, and nitration are such techniques. To conclude, polymer blending also results in membranes with improved surface characteristics. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Assessment of a semi-quantitative method for estimation of the rejection of organic compounds in aqueous solution in nanofiltrationJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 7 2006Bart Van der Bruggen Abstract A large number of different mechanisms describing the retention of dissolved organic compounds in nanofiltration have been proposed. A recent review identified the parameters possibly involved in the separation performance and suggested a qualitative classification of dissolved compounds. Continuing this approach, a semi-quantitative assessment of the observed rejections in nanofiltration is given in this paper, based on threshold values of key parameters such as molecular weight and molecular weight cut-off (MWCO), molecular size, pH and pKa, hydrophobicity (logKow) and membrane charge. Experimental values and literature data were used to provide a broad basis for comparison. It was concluded that (a) all categories that contain hydrophobic components are badly defined, in particular for small components, with rejections varying from low to very high, (b) all components that contain hydrophilic components have relatively high rejections and (c) all categories that contain charged components have well-defined, high rejections (intermediate for membranes with low surface charge). In all cases, the average rejection is higher when the component's molecular weight is larger than the MWCO of the membrane and when the molecular size is larger than the pore size of the membrane. Copyright © 2006 Society of Chemical Industry [source] Simple and simultaneous determination of sulphapyridine and acetylsulphapyridine in human serum by column-switching high-performance liquid chromatographyJOURNAL OF CLINICAL PHARMACY & THERAPEUTICS, Issue 6 2002D. Teshima PhD Summary Objective:, A high-performance liquid chromatography (HPLC) with an automated on-line column-switching system was used for the simultaneous determination of sulphapyridine and acetylsulphapyridine, two major active metabolites related to the adverse effects of sulphasalazine, in human serum. Methods:, Serum samples were directly injected into the HPLC, with the valve automatically switched on to remove serum proteins and other hydrophilic components remaining in the pre-column after elution of sulphapyridine and acetylsulphapyridine to the analytical column. Results:, Serum proteins did not interfere with the analysis of either compound. The recoveries of SLP and Ac-SLP from drug-free human serum were 93·03,99·18% and CV were 2·88,4·34%. The within-run reproducibility of assays was excellent with relative standard deviations (RSD) of 1·01,3·90% (SLP) and 0·77,5·56% (Ac-SLP). The limit of quantification of sulphapyridine and acetylsulphapyridine was 3·13 ,g/mL and 0·50 ,g/mL, respectively. The serum concentrations in a patient with ulcerative colitis, who took 1·0 g sulphasalazine twice daily, were 31·20 ,g/mL for sulphapyridine and 14·64 ,g/mL for acetylsulphapyridine at 7 h after ingestion. Conclusion:, The present simple and reproducible assay was useful for the monitoring of serum sulphapyridine and acetylsulphapyridine. [source] Three-Dimensional Polycaprolactone Hierarchical Scaffolds Supplemented with Natural Biomaterials to Enhance Mesenchymal Stem Cell ProliferationMACROMOLECULAR RAPID COMMUNICATIONS, Issue 19 2009Hyeon Yoon Abstract A hybrid technology that combines a three-dimensional (3-D) dispensing system with an electrospinning process was used to produce a hierarchical 3-D scaffold consisting of micro-sized polycaprolactone (PCL) strands and micro/nano-sized fibres. The micro/nanofibre biocomposites electrospun with PCL/small intestine submucosa (SIS) and PCL/Silk fibroin were layered between melt-plotted micro-strands. The scaffold containing SIS exhibited a stronger hydrophilic property than other scaffolds due to the various hydrophilic components in SIS. The 3-D hierarchical scaffold having biocomposites exhibited an incredibly enhanced initial cell attachment and proliferation of bone marrow-derived mesenchymal stem cells relative to the normally designed 3-D scaffold. [source] | ||||||||||