Results 1 - 10 of 7182
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[en] Mathematical methods of calculation of the critical conversion (gel point) in the formation of cross-linked polymers by polycondensation, cross-linking of macromolecules and three-dimensional polymerisation are considered. The results obtained using the statistical approach ('ideal' polycondensation), the concept of bond blocks (the 'non-ideal' or 'non-statistical' polycondensation) and kinetic calculations that allowed the determination of the gel point in three-dimensional polymerisation processes are discussed.
[en] Non-Hodgkin lymphoma symbolizes a heterogeneous group of diseases resulting from malignant transformation of lymphocytes with differing patterns of behavior and responses to treatment. The potential curability of non-Hodgkin lymphoma differs among the various histologic subtypes and is associated in part with the stage at presentation. CD19 antigen is a type I transmembrane glycoprotein belonging to the immunoglobulin Ig superfamily. CD19 is specifically expressed in normal and neoplastic B-cells. Recent study showed that in a mouse model, CD19 and c-Myc synergize functionally to accelerate B-cell lymphomagenesis, which is associated with increased disease severity. Specificity is the most important challenge in cancer therapeutics. Antibody–drug conjugates have the prospect of enhancing the therapeutic efficacy over unconjugated monoclonal antibodies through the selective delivery of cytotoxic agents to cancer cells. The ubiquitous expression of CD19 in these tumors, especially at an earlier stage and the property of efficient internalization, makes CD19 an attractive and affective target for antibody–drug conjugate therapy as compared to CD20. SAR3419 (huB4-DM4) is a novel antibody–drug conjugate that is composed of a humanized monoclonal IgG1 anti-CD19 antibody (huB4) attached to the potent cytotoxic drug, a maytansine derivative (DM4), through a cleavable disulfide cross-linking agent N-Succinimidyl-4-2-pyridyldithio butanoic acid (SPDB). The preclinical efficacy of maytansine derivative–anti-CD19 conjugate was demonstrated in our laboratory, and SAR3419 was found to be more effective than CHOP in a xenograft model. Phase I trials have also been conducted on the basis of preclinical studies that demonstrated promising antitumor activity with acceptable safety results in human B-cell lymphoma models. Additional trials are ongoing and will provide additional insight into the full potential of this novel drug
[en] In this work, proton exchange membranes (PEMs) based on chitosan (CS) and cellulose (CL) have been prepared using a solution-casting technique with sulfosuccinic acid (SSA) as an ionic cross linker. The characteristics of these CS-CL biocomposite membranes were studied using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), electrochemical impedance spectroscopy (EIS) in addition to the measurement of the water uptake rate (WUR) and the ion exchange capacity (IEC). The results indicate that the amount of SSA used in this study played a significant role in the proton conduction of the membrane. The proton conductivity of a cross-linked CS-CL membrane was on the order of 10-5 S cm-1, which is greater than the proton conductivity of a pure CS membrane. (author)
[en] By examining the effect of silicon gum and some additions mixed with high pressure polyethylene on the radiation cross-linking it was shown, that mechanical and electrical properties of plastic materials mixed with silicon gum has been greatly improved. Tin-organic compound itself does not give effect on the process of the radiation cross-linking, but it was established, that, when used with another stabilizer, it was protected from thermal oxidation. (author)
[en] Highlights: • Cross-linked (CL) laccase-metal hybrid nanoflower (NF) was prepared. • The catalytic efficiency of CL-NF laccase was 2.2-fold higher than that of free laccase. • CL-NF laccase showed 2.6-fold higher oxidation potential than free laccase towards phenolic compounds. • Under repeated batch conditions, it retained high decolorization efficiency for synthetic dyes. - Abstract: Herein, we report the preparation of a cross-linked protein-metal hybrid nanoflower (NF) system for laccase immobilization. The immobilized laccase showed effective encapsulation yield and activity recovery of 78.1% and 204%, respectively. The catalytic efficiency (kcatVmax-1) of cross-linked NF (CL-NF) was 2.2-fold more than that of free laccase. The CL-NF also exhibited significantly higher stability towards pH and temperature changes. It exhibited excellent storage stability and tolerance towards solvents and inhibitors as compared with the free enzyme. After 10 cycles of reuses, the NF and CL-NF laccase showed 41.2% and 92.3% residual activity, respectively. The CL-NF showed high oxidation potential, 265% that of the free enzyme, towards phenolic compounds. The CL-NF laccase retained the residual decolorization efficiency of up to 84.6% for synthetic dyes under repeated batch conditions of 10 cycles. These results suggested that the preparation of CL-NF is an effective approach to enhance the enzymatic properties and has great potential in many industrial applications.
[en] In our previous work, linear polyelectrolyte cross-linker-bridged hydrogel showed fast gelation within hours, which constrained in-depth deployment of such gels. In the present report, precipitation polymerization of bifunctional VBCTHt monomers in ethanol and acetonitrile generated the nano-gel cross-linkers bearing cyclic sulfonium moieties. The addition of nano-gels cross-linkers to partially hydrolyzed poly(acrylamide) formed covalently cross-linked in situ gels at the temperatures greater than 25 °C. As the morphology of the cross-linker changed from linear form to nano-gel in the state of sphere, the gelation time was controlled from 3 to 40 h. Nano-gel–HPAM system showed three orders of magnitude of delayed gelation while maintaining comparable mechanical integrity in comparison with conventional metallic cross-linked in situ gel, where sulfonium-functionalized nano-gel cross-linkers acting as covalent gelator were utilized for in situ gel formation. The change in cross-linker morphology and bonding nature of the gels dramatically extended gelation time. The mechanics of nano-gel cross-linker-derived covalently cross-linked HPAM in situ gels could be tuned by nano-gel cross-linkers concentration. The viscosity of HPAM and ionic cross-linker gelant had lower viscosity compared to conventional Cr3+–HPAM gel system as confirmed by rheological measurements. The gelant showed excellent salt and pH resistance, rendering it applicable to reservoir conditions. We believe this pioneer work in examination of cross-linker morphology to dictate hydrogel gelation offered the possibility to deploy mechanically tunable gels with delayed gelation for in-depth treatment of reservoir formation to improve fossil energy recovery.
[en] Restriction fragments of pUC19 DNA were irradiated by various doses of UV light and analyzed by denaturing (alkaline) agarose gel electrophoresis. The irradiation generated retarded species whose mobility indicated two crosslinked DNA strands. Quantitative analysis of the experimental data provided an empirical equation relating the fraction of crosslinked DNA molecules to their length and to the dose of their irradiation by UV light. This equation can be used to predict the crosslinking behavior of pUC19-like DNA molecules whose primary structures do not much differ from a random nucleotide sequence. The amount of interstrand crosslinks increased with the (A + T) content of the pUC19 DNA fragments but the dependence was not clear-cut to indicate that oligonucleotide composition of DNA played a significant role as well. (author)
[en] The behaviour of slightly crosslinked gels and their linear analogues under interaction with metal ions is compared. Complexes of poly-2-methyl-vinylpyridine (PVP) with LiClO4, AgNO3 and Cu(NO3)2 obtained on the boundary of two immiscible solvents benzene and water was studied. The composition of polymer-metal complexes which have been determined by means of viscosimeter method is found to be different depending upon the nature of metal ions. The ratio [PVP]:[salt] are equal to 2:1. 4:1 and 4:1 for AgNO3, LiClO4 and Cu(NO3)2 respectively. Both the TG and DTA evidence support an ordered structure of the polymer-metal complexes synthesis at the benzyne-water interface. Complex formation of mechanism of a linear and weakly cross-linked poly vinylpyridine with NaClO4 in methanol has been discussed. Both for viscometer and swelling coefficient data of the linear and cross-linked polymers evidence for the existence of two maximums, that can suggest of two different composition complexes are formed. Some important featuries of polymer behaviour depending on a condition of their existence in the system: either as free macromolecules with maximum conformational freedom of the chains or as moderately cross-linked gels with some limitation of chain flexibility