Incorporation methods for cholic acid chitosan-g-mPEG self-assembly micellar system containing camptothecin

A water-insoluble anticancer agent, camptothecin (CPT) was incorporated to a polymeric micelle carrier system preparing from cholic acid chitosan-grafted poly (ethylene glycol) methyl ether (CS-mPEG-CA). CS-mPEG-CA formed a core–shell micellar structure with a critical micelle concentration (CMC) of 7.08 μg/ml. Incorporation efficiency was investigated by varying physical incorporation method and initial drug loading. Among three incorporation methods (dialysis, emulsion and evaporation methods), an emulsion method showed the highest CPT incorporation efficiency. Increasing the initial CPT loading from 5 to 40%, the incorporation efficiency decreased. In all examined CPT-loaded CS-mPEG-CA micelles, 5% initial drug loading showed the highest drug incorporation efficiency. Release of CPT from the micelles was sustained when increasing the initial CPT loading. This indicates the importance of incorporation method and the initial drug loading to obtain the optimum particle size with high drug loading and sustained drug release. When compared to the unprotected CPT, CPT-loaded CS-mPEG-CA micelles were able to prevent the hydrolysis of the lactone group of the drug. This novel CS-mPEG-CA polymer presents considerable potential interest in the further development of CPT carrier.     

Simplified computations for standard-addition methods in ion-selective potentiometry

A fast iterative procedure is described for calculating the initial concentration or the slope of the calibration plot on the basis of two standard additions. An iterative non-linear least-squares procedure is reported for evaluation of the unknown concentration, slope and standard potential in the Nernst equation and the Basic program has only 56 statements.     

Effect of jute fibers on morphological characteristics and properties of thermoplastic starch/biodegradable polyester blend

Cellulose - The current work aims to study the effect of jute fiber (JF) on the characteristics and performance of a thermoplastic starch/poly(lactic acid)/poly(butylene adipate-co-terephthalate)...     

Transition temperature of anisotropic superconductors with kondo impurities

The Matsuura-Ichinose-Nagoako (MIN) model for Kondo impurities in a superconductor has been generalized to include the effect of gap anisotropy. Analytic results are obtained for the change in the transition temperature. It is shown that, in appropriate limits, one recovers the recent results of Schachinger and Carbotte and Okabe and Nagi. The resulting formulae yield corrections to those of MIN in the BCS isotropic model.     

Anomalous specific heat and nuclear spin relaxation in Al-transition metal alloys

A mechanism involving dislocation pinning by impurities is proposed to explain the anomalous lattice specific heat and the nuclear spin—lattice relaxation in Al—transition metal alloys.     

Superconducting composites: Calculation of the localized single-particle excitations

The problem of localized single-particle excitations for the geometry of a superconducting sphere embedded in another superconductor has been investigated. Assuming constant order parameters in both materials Bogoliubov equations are solved for the s-state. The dependence of the excitation energy on the particle size and the ratio of the order parameters is shown.     

Spatial variations of the order parameter around a Kondo impurity for T ⩽ Tc

Analytic expressions for the spatial variations of the order parameter around a Kondo impurity are obtained. The oscillatory contribution due to impurity scattering is calculated using the t-matrix of Matsuura which conveniently yields the general results below T_c. Differences between our values and those of Schlottmann are reported.     

Upper critical fields of ferromagnet/superconductor layered structures

The temperature dependence of the upper critical fields, both perpendicular H_c2 and parallel H_c2 to layer planes of ferromagnet/superconductor bi- and multilayers, is theoretically investigated. The secular equation of the superconducting order parameter for determining the phase diagram (H, T) is obtained by solving exactly the linearized Usadel equations in the multimode method taking into account the material parameter values. For the bilayers system, the influence of the boundary resistivity on the critical fields, and the dimensional crossover behavior of H_c2(T) are studied in details. For the multilayered structure, the effects of the π-phase state on both the superconducting transition temperature T_c and the upper critical fields (H_c2, and H_c2) are also considered. The nonmonotonic T_c behaviors are predicted. The interplay between 0- and π-phases leading to the strong oscillations of T_c as well as the temperature dependence of the zero temperature critical fields on the ferromagnetic layer thickness are investigated theoretically.     

Monte carlo method in calculation of the melting temperatures of silicate glasses

Numerical constants for the various oxides for calculating the melting temperature of silicate glasses are re-determined by using a simple Monte Carlo method. These constants are used to calculate the melting temperatures of 60 glass compositions; the deviations of the calculated values from the practical melting temperatures are small compared with those obtained with an earlier method.     

Controlled hydrophobic/hydrophilic chitosan: colloidal phenomena and nanosphere formation

N-Phthaloylchitosan-grafted poly(ethylene glycol) methyl ether (mPEG) gives a milky solution when dispersed in water and a series of solvents. The appearance of turbidity depends on the types of solvents, i.e., protic and aprotic solvents. N-Phthaloylchitosan-grafted mPEG shows an aggregation of sphere-like particles as observed by scanning electron microscopy. Transmission electron microscopy indicates that the spheres are at the nano level. When the chain length of mPEG is as high as 5×10³ Da the sphere size becomes as small as 80–100 nm on average as observed by transmission electron microscopy. By simply adjusting the hydrophobicity/hydrophilicity of the chitosan chain, a stable nanosphere can be obtained directly.