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991.
Analysis of proteoglycans derived sulphated disaccharides by liquid chromatography/mass spectrometry
A method has been developed for the identification and quantitative determination of sulphated disaccharides derived from chondroitin sulphate (CS) and dermatan sulphate (DS) chains attached to proteoglycans (PGs). After digestion with Chondroitinase ABC, the pool of disaccharides can be directly separated by liquid chromatography on a porous graphitized carbon (PGC) column and identified by on-line electrospray mass spectrometry under negative ionization conditions. The relative intensities of the fragment ions obtained by MS/MS allow to distinguish the sulphate position. Calibration with standard disaccharides allows the quantification of the different isomers. The method showed good repeatability in terms of relative standard deviation (RSD < 2%) and linearity between 0.5 and 50 ng (total injected amount) for both 4- and 6-sulphated disaccharides. The limit of detection achieved in full scan mode was 0.1 ng. The methodology was applied to different types of biological samples obtained from patients suffering from chronic lung inflammation such as: lung tissue, bronchoalveolar lavage fluid (BALF), induced sputum and urine. 相似文献
992.
The strength characteristics of composites based on four types of modified epoxy resins and reinforced with carbon fabric were studied as influenced by the filler content. The experimental and theoretical strength parameters of the composites were compared. The correlation between the adhesion strength at the polymeric binder-filler boundary and the impact resilience of the composites was evaluated; a procedure was proposed for predicting the impact resilience of the reinforced composites. 相似文献
993.
Alan V Chadwick Shelley L P Savin Ricardo Alcántara Diego Fernández Lisbona Pedro Lavela Gregorio F Ortiz José L Tirado 《Chemphyschem》2006,7(5):1086-1091
Lithium cobalt oxide (LiCoO(2)) particles are modified using rotor blade grinding and re-annealing and used as the active electrode material versus lithium in the 3-0 V potential interval, in which a maximum capacity of 903 mA h g(-1) is achieved. X-ray absorption near edge structure spectra reveal the complete reduction of Co(3+) to Co metal at 0 V. Cell recharge leads to an incomplete reoxidation of cobalt. A maximum reversible capacity of 812 mA h g(-1) is obtained, although a poor capacity retention upon prolonged cycling may limit its application. 相似文献
994.
Liviu Sacarescu Rodinel Ardeleanu Gabriela Sacarescu Mihaela Simionescu 《European Polymer Journal》2004,40(1):57-62
This paper presents the synthesis of new polysilane with pendant crown ether groups. The polymer was obtained through the addition reaction of 4′-allylbenzo-15-crown-5 to poly[methyl(H)-co-methylphenylsilane] copolymer in anhydrous toluene solution using hexachloroplatinic acid as a catalyst. The allyl functionalization of the crown ether was achieved by the coupling of the crown ether bromide with allyl magnesium chloride. The availability of the crown ether sites in complexation reactions with Cu(II) cations was tested.The chemical structures of all products and intermediates were studied using spectral methods (IR, 1H-NMR, 13C-NMR, UV), gel permeation chromatography (GPC) and thermogravimetric analysis (TGA). 相似文献
995.
Mihaela Prajinaru Natalia Hurduc Silvia Alazaroaie Otilia Catanescu Nicolae Hurduc 《Central European Journal of Chemistry》2003,1(4):387-401
The paper presents a study of the thermal properties of some aromatic polyethers obtained by phase trasfer catalysis technique.
The polymes were synthesized starting from 1,8-dichloro-octane and various bisphenols: 4,4′-dihydroxyazobenzene, 4,4′-dihydroxydiphenyl,
bisphenol A and 2,7-dihydroxynaphthalene. Molecular simulations were performed in order to obtain supplementary information
concerning the chain conformation and inter-chain interactions. The presence of azobenzenic moieties induces high phase transition
values, situated near the thermal stability limit. Therefore, the thermogravimetrical study of these polymers is very important
for establishing the temperature limits for DSC and optical microscopy studies. All the polymers present a good thermal stability
situated above the isotropization values. In these circumstances no special precautions are necessary for the characterization
methods of the liquid crystalline behavior. The kinetic characteristics suggest a similar degradation mechanism by successive
reactions. The inter-chain interactions do not influence the thermostability of the samples if the polar surface of the polymer
is situated below a certain value. 相似文献
996.
Mureseanu M Galarneau A Renard G Fajula F 《Langmuir : the ACS journal of surfaces and colloids》2005,21(10):4648-4655
A new mesoporous micelle-templated silica (MTS) route for enzyme encapsulation is presented. The pore structure is given by a new association oflecithin (double chain surfactant) and dodecylamine as cosurfactant. To enhance and to well protect the enzyme activity, lactose was loaded in the synthesis. The mixed-micelles give after the addition of tetraethyl orthosilicate a well-ordered mesoporous material with a spongelike rigid structure stable after calcination at 550 degrees C. The size of the pores lies between 30 and 40 A, matching well with the size of the lipases. The activity of this heterogeneous catalyst was tested in the hydrolysis of the ethylthiodecanoate. These new biocatalysts were very active, more than hydrophobic sol-gel materials and commercially available sol-gel encapsulated lipase. This new MTS synthesis route allows one to encapsulate in one-step various enzymes, even those that are very fragile. 相似文献
997.
Some new poly(amide-imide) siloxane copolymers have been synthesized by solution polycondensation of some aromatic diamines with siloxanic diacids having preformed imide rings. Two polycondensation techniques were used: polycondensation of aromatic diamines with diacid chlorides and direct polycondensation of aromatic diamines with diacids in the presence of organic phosphites, following the Yamazaki-Higashi phosphorylation technique. In all cases the reactions were carried out using equimolecular amounts of the two monomers, in polar aprotic solvents and inert atmosphere.The obtained compounds were characterized by elemental C, H and Si analysis, solubility tests, IR and 1H-NMR spectrometry. Thermogravimetric curves were also recorded. All data agree with the proposed structures. 相似文献
998.
Iulian Corneliu AlupeiMarcel Popa Mihaela HamcerencuM.J.M. Abadie 《European Polymer Journal》2002,38(11):2313-2320
The swelling properties of some superabsorbant composite hydrogels, based on xanthan and poly(vinyl alcohol) and crosslinked with epichlorohydrin, were studied. The maximum swelling degree of the hydrogels and the swelling rate constant were determined as a function of the hydrogel's composition (the % of poly(vinyl alcohol) in the polymer mixture and the amount of crosslinking agent), the crosslinking reaction conditions (the time and the temperature of the crosslinking reaction), and the composition of the swelling solutions (the glycerin/water ratio and the concentration of the electrolyte). 相似文献
999.
Armin Burkhardt Ulrich Wedig Hans Georg von Schnering Andreas Savin 《无机化学与普通化学杂志》1993,619(3):437-441
The Electron Localization Function in closo Boron Clusters The structure and the electron density in the closo boron clusters B4X4 (X = H, Cl, Br, I), B6X62? (X = H, Cl, Br, I) and B12H122? were determined by pseudopotential Hartree-Fock calculations. The Electron Localization Function (ELF) was used to interpret the bonding characteristics. The regions of high ELF values in all cases have the form of the dual polyhedron of the boron cage. They show perfectly the 3 center 2 electron bonds. The comparison between Hartree-Fock and Extended Hückel calculations point out that semiempirical calculations can also be a good basis for ELF interpretations. 相似文献
1000.
This paper reports the investigation of the thermal
stability of a series of new complexes with azo and azomethinic chromophores
of the type [Er(HL)2(H2O)2](HO);
((B) H2L: o,o’-dihydroxy-azobenzene (A);
(D) H2L: N-(2-hydroxy-1-naphthalidene)aminophenol
(C); (F)
H2L: N-(2-hydroxy-1-naphthalidene)anthranilic acid
(E)). The complexes thermal behaviour steps
were investigated and comparatively presented with those of corresponding
ligand. The thermal transformations are complex processes according to TG
and DTG curves including phenol elimination, oxidative condensation and thermolysis
processes. The final product of complexes decomposition is Er2O3. 相似文献