Microwave-assisted synthesis of anion-exchange resins for sorption of noble metals: how to boost sorption capacity using a proper reaction environment

In the present studies a series of anion-exchange resins was synthesized in a microwave field. The 1,6-diaminohexane functionalized resins were obtained in presence of selected organic solvents, N,N-dimethyl formamide, dimethyl sulfoxide and 1-methyl-2-pyrrolidone. The resins were employed in batch and dynamic processes of Au(III), Pt(IV) and Pd(II) sorption from tricomponent systems in 0.1 M HCl. The experiment was designed in a way that allowed to determine the use of a specific solvent in the microwave field and how it impacts on properties of the anion exchangers. An influence of a reaction environment was discussed taking into account i.e., dielectric characteristics of the specific solvent, efficiency of the syntheses processes as well as the maximum sorption capacity of the resins. Ultimately the application of a specific reaction environment was set together with sorption of noble metals ability and evaluated using infrared spectroscopy. The proceeded analyzes allowed to determine which organic solvent from the selected ones is the most suitable for microwave-assisted synthesis of the anion-exchange resins.     

Analysis of wet oxidation process after initial thermohydrolysis of excess sewage sludge

The authors propose a new technique to analyse a complex process of wet oxidation of excess sewage sludge by separating thermohydrolysis that results in the separation of sewage sludge into hydrolysates: solid and liquid products, from the basic process of oxidation of the two products. Wet oxidation kinetics was studied at different temperatures of both products based on the measurement of total organic carbon during the process with the use of a PARR high-pressure reactor. Decomposition of the liquid product leads to the formation of non-degradable and gaseous final products, while degradation of the solid product-via an intermediate liquid product-also leads to the formation of final and gaseous products. Solution of the kinetic equations that describe the dependence of relative organic carbon concentration on time is well illustrated by experimental results. On the basis of fitting theoretical curves to the experimental results, the kinetic parameters of the process were determined.     

Three-dimensional nonwoven scaffolds from a novel biodegradable poly(ester amide) for tissue engineering applications

Biodegradable polyesters are established biomaterials in medicine due to their chemical characteristics and options for material processing. A main problem, however, is the release of acid degradation products during biodegradation with severe local pH-drops and inflammatory reactions. Polyesteramides, in contrast, show a less prominent pH-drop during degradation. In this study, we developed a simple, reproducible synthesis of the poly(ester amide) (PEA) type C starting from ε-caprolactame, 1,4-butanediol, and adipic acid in a one-batch two-step reaction and conducted the manufacturing of PEA-derived 3D textile scaffolds applicable for tissue engineering purposes. The thermal and mechanical properties of PEA-type C were analysed and the structural conformity of different batches was confirmed by NMR spectroscopy and size exclusion chromatography. The polymer was formed into nonwovens by textile manufacturing. Cytotoxicity tests and X-ray photoelectron spectroscopy (XPS) were used to analyze the effect of scaffold extraction before cell seeding. The manufactured carriers were seeded with human preadipocytes and examined for cellular proliferation and differentiation. The production of PEA type C successfully occurred via simultaneous ring-opening polymerization of ε-caprolactame and polycondensation with 1,4-butanediol and adipic acid at 250 °C under high-vacuum. Soxhlet extraction allowed optimal cleaning of nonwoven scaffolds. Extracted PEA-derived matrices were capable of allowing good adherence, proliferation, and differentiation of preadipocytes. These results are encouraging and guidance towards an optimally prepared nonwoven carrier applicable for clinical use. K. Hemmrich and J. Salber have contributed equally.     

Glycol-modified silanes: novel possibilities for the synthesis of hierarchically organized (hybrid) porous materials

The preparation of porous hierarchical architectures that have structural features spanning from the nanometer to micrometer and even larger dimensions and that exhibit certain functionalities is one of the new challenging frontiers in materials chemistry. The sol-gel process is one of the most promising synthesis routes toward such materials because it not only offers the possibility to incorporate organic functions into the porous host but also offers the possibility to deliberately tailor the pore structure. In this Account, the opportunities given by the application of novel diol-modified silanes are discussed for the synthesis of hierarchically organized inorganic and also inorganic-organic porous monoliths.     

Nanocrystalline diamond--an excellent platform for life science applications

Nanocrystalline diamond (NCD) has recently been successfully utilized in a variety of life science applications. NCD films are favorable and salubrious substrates for cells during cultivation. Therefore NCD has also been employed in tissue engineering strategies. NCD as reported in this contribution was grown by means of a modified hot-filament chemical vapor deposition technique, which results in less than 3% sp2-hybridization and yields grain sizes of 5-20 nm. After production the NCD surface was rather hydrophobic, however it could be efficiently refined to exhibit more hydrophilic properties. Changing of the surface structure was found to be an efficient means to influence growth and differentiation capacity of a variety of cells. The particular needs for any given cell type has to be proven empirically. Yet flexible features of NCD appear to be superior to plastic surfaces which can be hardly changed in quality. Besides its molecular properties, crystal structural peculiarities of NCD appear to influence cell growth as well. In our attempt to facilitate, highly specialized applications in biomedicine, we recently discovered that growth factors can be tightly bound to NCD by mere physisorption. Hence, combination of surface functionalization together with further options to coat NCD with any kind of three-dimensional structure opens up new avenues for many more applications. In fact, high through-put protein profiling of early disease stages may become possible from serum samples, because proteins bound to NCD can now be efficiently analyzed by MALDI/TOF-MS. Given these results, it is to be presumed that the physical properties and effective electrochemical characteristics of NCD will allow tailoring devices suitable for many more diagnostic as well as therapeutic applications.     

Effect of multiblock copolymers in polymer blends

The use of multiblock copolymers for the compatibilization of immiscible polymer blends is controversially discussed in the literature. Investigations have been carried out to estimate the effect of multiblock copolymers containing segments of a liquid crystalline polyester (LCP) and polysulfone (PSU) segments in blends of the based homopolymers. One goal was to determine whether multiblock copolymers provide an opportunity for compatibilizing PSU/LCP blends. By using PSU/LCP multiblock copolymers with different molecular weights of the blocks in the appropriate binary, solution-casted blends, it was shown that the interpenetration of the polysulfone phase of the block copolymer and the PSU matrix leads to an improved miscibility of the blend. This effect is retained in ternary blends of PSU, LCP, and the multiblock copolymer, assuming a certain critical molecular weight of the multiblock copolymer segments. In addition, some mechanical characteristics of PSU/LCP melt blends such as the E-modulus and fracture strength are improved by adding long-segmented multiblock copolymers. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2293–2309, 1997     

Major bridge development in Hong Kong,China—past,present and future

The first “modern” type of vehicular bridge was built in Hong Kong China in the 1920s. The need for an efficient transportation system to cope with population growth and enable economic development has demanded the construction of more and more bridges since the middle of the 20th century. By 2007, Hong Kong had a total of about 1300 vehicular bridges. Four of these bridges, including the Tsing Ma Bridge, Kap Shui Mun Bridge, Ting Kau Bridge, and the cable-stayed bridge on the Hong Kong- Shenzhen Western Corridor, are considered to be major bridges supported by cables. Currently, the Stonecutters Bridge on Route No. 8 is under construction and is expected to be completed in late 2009. At the same time, the Hong Kong-Zhuhai-Macao Bridge will be in its detailed design stage soon. While efforts have been made by bridge builders to construct these giant structures, the upkeeping of these valuable assets at a high standard and ensuring their continuous functioning and performance during their intended lifespans will be another important task for bridge engineers. Wind and structural health monitoring system (WASHMS) will play a key role in this respect.