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601.
Viktoria Weber Marion Ettenauer Ingrid Linsberger Fritz Loth Katrin Thümmler Andreas Feldner Steffen Fischer Dieter Falkenhagen 《Macromolecular Symposia》2010,294(2):90-95
Therapeutic apheresis is established as supportive therapy for various diseases, such as hypercholesterolemia, autoimmune diseases, liver failure, and sepsis. In combined membrane-adsorption systems, the patient's plasma is continuously separated from whole blood by means of a hollow fiber filter, and pathogenic factors are removed from the plasma by selective or specific adsorbents. While adsorbent particles with a size range of 300–800 µm are used in conventional systems, we are currently developing a system based on adsorbent microparticles (1–5 µm), the Microspheres-Based Detoxification System (MDS). The characteristics of the matrix used for immobilization of specific ligands influence the performance of the resulting adsorbents. Desirable matrix characteristics are an open porous structure with an inner surface accessible for target molecules, mechanical stability, narrow particle size distribution, and ease of derivatization. In addition, biocompatibility is a critical issue, since the particles are in direct contact with the patient's plasma. Cellulose represents an ideal support matrix, as it combines all the above-mentioned features, and cellulosic polymers are widely applied in medicine and generally regarded as biocompatible. Cellulose microparticles can be activated using e.g. sodium periodate and functionalized with Polymyxin B or anti-tumor necrosis factor (TNF) antibodies to generate specific adsorbents for endotoxins or TNF. In summary, cellulose microparticles represent an excellent matrix as basis for adsorbent development in blood purification. 相似文献
602.
Padma Ambalam Kanthi Kiran Kondepudi Ingrid Nilsson Torkel Wadström Åsa Ljungh 《Applied biochemistry and biotechnology》2014,172(4):1970-1981
Twenty-four human bifidobacterial strains were analysed for cell surface hydrophobicity (CSH) using a salt aggregation test (SAT) and a Congo red binding (CRB) assay. Three strains were selected for a systematic study on the CSH and biofilm formation: Bifidobacterium breve 46, Bifidobacterium animalis ssp. lactis 8:8 and a reference strain B. animalis ssp. lactis JCM 10602. CRB of the B. breve 46 and B. animalis ssp. lactis JCM 10602 was significantly enhanced (P?<?0.05) when grown in deMan–Rogosa–Sharpe cysteine (MRSC) broth supplemented with taurocholic acid (TA) or native porcine bile (PB). An enhanced CSH of the strains grown with PB and gastric mucin correlated with an increased mucin binding and an enhanced biofilm formation in prebiotic oligosaccharide-supplemented cultures. The three strains showed late bile-induced biofilm (72 h) under an anaerobic growth condition, and both B. animalis ssp. lactis strains showed a late bile-induced biofilm formation under aerobic conditions shown by crystal violet staining. These two strains were thus considered to be oxygen tolerant and more robust. Furthermore, enhanced biofilm formation of these robust bifidobacterial strains in the presence of prebiotics may allow for strong colonisation in the gastrointestinal tract when administered to in vivo models as a “synbiotic supplement”. 相似文献
603.
Deshayes G Poelmans K Verbruggen I Camacho-Camacho C Degée P Pinoie V Martins JC Piotto M Biesemans M Willem R Dubois P 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(15):4552-4561
Dialkyltin dichloride grafted to a cross-linked polystyrene, with the formula [P-H]((1-t))[P-(CH2)nSnBuCl2]t (P=[CH2CH(pC6H4)], t=the degree of functionalization, and n=6 or 11), is investigated as a recyclable catalyst in the ring-opening polymerization (ROP) of epsilon-caprolactone (CL). It is demonstrated that high-resolution magic-angle-spinning (HR-MAS) NMR spectroscopy is an invaluable tool to characterize completely the supported catalyst. The 2D 1H-13C HSQC HR-MAS spectrum, in particular, allowed extensive assignment of the 1H and 13C resonances, as well as accurate measurement of the (n)J((1)H-(117/119)Sn) and (n)J((13)C-(117/119)Sn) coupling constants. 1H and 119Sn HR-MAS NMR spectroscopy is presented as a monitoring tool for catalytic processes based on organotin compounds, particularly for the investigation of the extent to which polymerization residues are observable in situ in the material pores and for the assessment of the chemical integrity and recycling conditions of the grafted catalyst. From polymerization experiments with CL, initiated by n-propanol and with [P-H]((1-t))[P-(CH2)nSnBuCl2]t of various compositions as the supported catalyst, it appears that a partial 'burst' of the polystyrene support occurs when the length of the alkyl spacer is limited to n=6, as a result of polymer chains growing within the pores of the support. However, extension of the length of the aliphatic polymethylene spacer from 6 to 11 carbon atoms preserves the support integrity and allows the production of catalyst-deprived poly(epsilon-caprolactone) (PCL) oligomers. A preliminary attempt to recycle the heterogeneous catalyst has shown that very good reproducibility can be obtained, in terms of both catalyst activity and molecular-weight parameters of the as-recovered PCL polyester chains. 相似文献
604.
Wu D Lenhardt JM Black AL Akhremitchev BB Craig SL 《Journal of the American Chemical Society》2010,132(45):15936-15938
Single-molecule force spectroscopy is used to observe the irreversible extension of a gem-dibromocyclopropane (gDBC)-functionalized polybutadiene under tension, a process akin to polymer necking at a single-molecule level. The extension of close to 28% in the contour length of the polymer backbone occurs at roughly 1.2 nN (tip velocity of 3 μm/s) and is attributed to the force-induced isomerization of the gDBCs into 2,3-dibromoalkenes. The rearrangement represents a possible new mechanism for localized stress relief in polymers and polymer networks under load, and the quantification of the force dependency provides a benchmark value for further studies of mechanically triggered chemistry in bulk polymers. 相似文献
605.
Ingrid M. Dittert Jessee S.A. Silva Rennan G.O. Araujo Adilson J. Curtius Bernhard Welz Helmut Becker-Ross 《Spectrochimica Acta Part B: Atomic Spectroscopy》2009
A simple, fast and sensitive direct method for the simultaneous determination of Cr and Fe in crude oil samples is proposed using high-resolution continuum source graphite furnace atomic absorption spectrometry. No sample preparation is used except for a 10-minute homogenization in an ultrasonic bath. Aliquots of 0.1–4 mg of the samples are weighed onto solid sampling platforms and analyzed directly using aqueous standards for calibration. The simultaneous determination was possible because there is a secondary Fe line at 358.120 nm in the vicinity of the most sensitive Cr line at 357.868 nm, and both absorption lines were within the wavelength interval covered by the linear charge-coupled device array detector. It has also been of advantage that the sensitivity ratio between the two analytical lines corresponded roughly to the concentration ratio of the two elements found in crude oil, and that both analytes have very similar volatility, so that no compromises had to be made regarding pyrolysis and atomization temperatures. Two oil reference materials have been analyzed and the results were in agreement with the certified or reported values. Characteristic masses of 3.6 pg and 0.5 ng were obtained for Cr and Fe, respectively. The limits of detection (3σ, n = 10) were 1 µg kg− 1 for Cr and 0.6 mg kg− 1 for Fe, and the precision, expressed as the relative standard deviation, ranged from 4 to 20%, which is often acceptable for a rapid direct analytical procedure. Five crude oils samples were analyzed. 相似文献
606.
Lenhardt JM Ogle JW Ong MT Choe R Martinez TJ Craig SL 《Journal of the American Chemical Society》2011,133(10):3222-3225
Tension along a polymer chain traps neighboring s-trans/s-trans-1,3-diradicals from the mechanically induced ring opening of gem-difluorocyclopropanes (gDFCs). The diradicals correspond to the transition states of the force-free thermal isomerization reactions of gDFCs, and the tension trapping allows a new disproportionation reaction between two simultaneously trapped diradicals to take place. 相似文献
607.
608.
Hechun Lin Peter W. de Oliveira Ingrid Grobelsek Aude Haettich Prof. Dr. Dr. h. c. Michael Veith 《无机化学与普通化学杂志》2010,636(11):1947-1954
The solvothermal reactions of Ti(OiPr)4 in alcohol using ionic liquid as additive were investigated. In the presence of [BMIM][Cl], [BMIM][Br], [BMIM][NTf2], [BMIM][SO3Me], [BMIM][SO4Me], or [BMIM][OTf] (BMIM = 1‐Butyl‐3‐methylimidazolium), pure anatase nanoparticles were obtained. The controlled hydrolysis of Ti(OiPr)4 in the presence of ionic liquids to form titanium oxo clusters plays a key role in the formation of anatase nanostructures, and ionic liquids can be repeatedly used to synthesise anatase nanoparticles. However, in the presence of [BMIM][PF6], [BMIM]2[Ti(OH)6] was obtained by an anion exchange reaction. 相似文献
609.
Loerting T Schustereder W Winkel K Salzmann CG Kohl I Mayer E 《Physical review letters》2006,96(2):025702
On compressing low-density amorphous ice (LDA) at 125 K up to 1.6 GPa, two distinct density steps accompanied by heat evolution are observable in pressure-density curves. Samples recovered to 77 K and 1 bar after the first and second steps show the x-ray diffraction pattern of high-density amorphous ice (HDA) and very HDA (VHDA), respectively. The compression of the once formed HDA takes place linearly in density up to 0.95 GPa, where nonlinear densification and HDA --> VHDA conversion is initiated. This implies a stepwise formation process LDA--> HDA --> VHDA at 125 K, which is to the best of our knowledge the first observation of a stepwise amorphous-amorphous-amorphous transformation sequence. We infer that the relation of HDA and VHDA is very similar to the relation between LDA and HDA except for a higher activation barrier between the former. We discuss the two options of thermodynamic versus kinetic origin of the phenomenon. 相似文献
610.