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Cellulose ethers are important materials with numerous applications in pharmaceutical industry. They are widely employed as stabilizers and viscosity enhancers for dispersed systems, binders in granulation process and as film formers for tablets. These polymers, however, exhibit challenge during preparation of their aqueous dispersions. Rapid hydration of their surfaces causes formation of a gel that prevents water from reaching the inner core of the particle. Moreover, the surfaces of these particles become sticky, thus leading to agglomeration, eventually reducing their dispersion kinetics. Numerous procedures have been tested to improve dispersibility of cellulose ethers. These include the use of cross-linking agents, alteration in the synthesis process, adjustment of water content of cellulose ether, modification by attaching hydrophobic substituents and co-processing using various excipients. Among these, co-processing has provided the most encouraging results. This review focuses on the molecular mechanisms responsible for the poor dispersibility of cellulose ethers and the role of co-processing technologies in overcoming the challenge. An attempt has been made to highlight various co-processing techniques and specific role of excipients used for co-processing.

Due to overexploitation of renewable resources, we have observed that some species are already extinct. So, the time demands conservation, reproduction and optimal utilization of these resources and the study of such problems. In this paper, a delayed stage-structured self-dependent two compartment (compartment-I contains immature fishes and compartment-II contains mature fishes) commercial fishery model with impulsive harvesting is proposed and analyzed mathematically as well as numerically. The aim is to manage the fishery resource system and that to extract maximum profit without the species become extinct. The proposed system is proved to have positive periodic solutions which are bounded, locally stable and permanent with certain conditions. Then by using optimal impulsive harvesting theory, the optimal harvesting time and optimal harvesting level have been obtained. At last, numerical simulation has been done to support the analytic results, along with comparative plots drawn for different values of harvesting effort E, maturation delay τ and impulsive period T .

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