Temperature responsive DDSs

Dang JM, Sun DD, Shin-Ya Y, Sieber AN, Kostuik JP, Leong KW. Temperature-responsive hydroxylbutyl chitosan for the culture of mesenchymal stem cells and intervertebral stem cells. Biomaterials 2006 27 406 18. 

The cure reactions, the viscosity-time-temperature profile, the processing conditions, the resultant epoxy chemical and physical structure, and the mechanical response of a C-fiber/TGDDM-DDS cured epoxy composite are modified by the presence of a BF3-amine complex catalyst within the prepreg. These factors also will be modified... 

Thus, at room temperature, the molecular motions responsible for the mechanical losses of poly(cyclopentyl methacrylate) and poly(cycloheptyl methacrylate) are very rapid processes, having too-high a frequency to broaden the line widths of MAS CP DD 13C NMR spectra, in agreement with the absence of observable motional broadening in the spectra of these two polymers (Fig. 8a and c). 

Cross-linked polymer gels that switch on and off the supply of drug or biomolecules in response to changes in temperature and/or pH have been developed [36-41], An electrically controlled DDS has also been developed. For example, insulin was entrapped in a poly(dimethylaminopropyl acrylamide) (PDMAPAA) gel and the delivery was controlled by electrical stimulation. As seen in Fig. 15, periodic on and off release of the protein molecule was obtained with numerous alternating applications of an electric field [42]. The response of the gel is quite sharp, and no leakage of the insulin during the off time was observed. Similarly, endrophonium chloride was released in an of-off pattern from poly(AMPS) copolymers with electric stimuli [43]. 

The major material inputs to the DD simulations include the elastic constants and the Burgers vector at the chosen pressure and temperature conditions, as well as the pressure-dependent parameters used in the mobility functions. All of these quantities are explicitly calculated at the atomistic level, as described in Sections 3 and 4 of this paper. The loading condition for the DD simulations is typically constant strain rate. The major outputs are stress-strain response and the dislocation density changes. In Section 5.2, we discuss the details of the simulation of high-pressure yield streugths for Ta and Mo single crystals. 

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