Ge-on-insulator lateral p-i-n waveguide photodetectors for optical communication.

We report high-performance lateral p-i-n Ge waveguide photodetectors (WGPDs) on a Ge-on-insulator (GOI) platform that could be integrated with electronic-photonic integrated circuits (EPICs) for communication applications. The high-quality Ge layer affords a low absolute dark current. A tensile strain of 0.144% in the Ge active layers narrows the direct bandgap to enable efficient photodetection over the entire range of C- and L-bands. The low-index insulator layer enhances optical confinement, resulting in a good optical responsivity. These results demonstrate the feasibility of planar Ge WGPDs for monolithic GOI-based EPICs.

Analysis of aroma compounds and nutrient contents of mabolo (Diospyros blancoi A. DC.), an ethnobotanical fruit of Austronesian Taiwan.

Diospyros blancoi A. DC. is an evergreen tree species of high-quality wood. Mabolo, the fruit of this plant, is popular among the natives in Taiwan, but its potential in economic use has not been fully explored. Mabolo has a rich aroma. Of the 39 different volatile compounds isolated, its intact fruit and peel were found to both contain 24 compounds, whereas the pulp contained 28 compounds. The most important aroma compounds were esters and α-farnesene. Our data show that mabolo is rich in dietary fiber (3.2%), and the contents of other nutrients such as malic acid, vitamin B2, vitamin B3, folic acid, pantothenic acid, and choline chloride were 227.1 mg/100 g, 0.075 mg/100 g, 0.157 mg/100 g, 0.623 mg/100 g, 0.19 mg/100 g, and 62.52 mg/100 g, respectively. Moreover, it is rich in calcium and zinc; the contents of which were found to be 42.8 mg/100 g and 3.6 mg/100 g, respectively. Our results show that D. blancoi has the potential to be bred for a novel fruit.

Formulation and process optimization of multiparticulate pulsatile system delivered by osmotic pressure-activated rupturable membrane.

In this study, a multiparticulate pulsatile drug delivery system activated by a rupturable controlled-release membrane (Eudragit(®) RS) via osmotic pressure (with NaCl as the osmogent) was developed and characterized for omeprazole, omeprazole sodium, and propranolol HCl which have different water solubilities. Multiparticulates in pellet form for incorporation with or without the osmogent were manufactured by three methods and then used to coat a polymeric membrane. Results demonstrated that drug/osmogent-containing pellets manufactured by the extrusion/spheronization method with incorporation of the osmogent were optimal. The lag time (tL) to initiate pulsatile release is regulated by tL=l(2)/(6×D), which is dependent on the coating levels (l(2)) and plasticizer content (D). The pulsatile release pattern was found to be dependent on the osmotic pressure (osmogent), drug solubility, and mechanical properties of the polymeric membrane (elasticity and toughness). Omeprazole with lower water solubility could not generate sufficient osmotic pressure to create a crack in the membrane to activate pulsatile release, whereas the two other model drugs with higher solubilities could. But adsorption of omeprazole sodium on Eudragit(®) RS via charge-charge interactions led the its incomplete release. Finally, with 4% osmogent of NaCl added, a lag time in a range from 0 to 12h proportionally regulated by varying both the membrane thickness and plasticizer level initiated the complete pulsatile release of propranolol HCl. In conclusion, a multiparticulate pulsatile drug delivery system activated by a rupturable controlled-release membrane via osmotic pressure was successfully developed, and clinical applications of chronotherapy with drugs like propranolol HCl are expected.

Characterizations of plasticized polymeric film coatings for preparing multiple-unit floating drug delivery systems (muFDDSs) with controlled-release characteristics.

Effervescent multiple-unit floating drug delivery systems (muFDDSs) consisting of drug (lorsartan)- and effervescent (sodium bicarbonate)-containing pellets were characterized in this study. The mechanical properties (stress and strain at rupture, Young's modulus, and toughness) of these plasticized polymeric films of acrylic (Eudragit RS, RL, and NE) and cellulosic materials (ethyl cellulose (EC), and Surelease) were examined by a dynamic mechanical analyzer. Results demonstrated that polymeric films prepared from Surelease and EC were brittle with less elongation compared to acrylic films. Eudragit NE films were very flexible in both the dry and wet states. Because plasticizer leached from polymeric films during exposure to the aqueous medium, plasticization of wet Eudragit RS and RL films with 15% triethyl citrate (TEC) or diethyl phthalate (DEP) resulted in less elongation. DEP might be the plasticizer of choice among the plasticizers examined in this study for Eudragit RL to provide muFDDSs with a short time for all pellets to float (TPF) and a longer period of floating. Eudragit RL and RS at a 1∶1 ratio plasticized with 15% DEP were optimally selected as the coating membrane for the floating system. Although the release of losartan from the pellets was still too fast as a result of losartan being freely soluble in water, muFDDSs coated with Eudragit RL and RS at a 1∶1 ratio might have potential use for the sustained release of water-insoluble or the un-ionized form of drugs from gastroretentive drug delivery systems.