A novel design of two-way multimedia loudspeaker
A multimedia loudspeaker usually stands on a desk, so the reflected sound from the desk interferes with the direct sound from the loudspeaker. Reflected sound from the desk must be taken into consideration in the designing process in order to obtain the flattest possible resultant frequency response in the listening position. This paper introduces a novel design of a two-way multimedia loudspeaker, which gives flat frequency response at broad range of distances from the listener.
A High Fidelity Small-sized Loudspeaker
Although bass sound reproduction through a small-sized loudspeaker requires large diaphragm displacement, the conventional supporting system cannot vibrate at an amplitude large enough for high-quality bass sound reproduction. A new supporting system is proposed which solves the problem of the conventional supporting system and focuses on the high excursion supporting system in terms of structure and displacement mechanism, in comparison with the conventional system. Using the supporting system with improved amplitude linearity and a driving system with a high force factor, a small-sized loudspeaker 8 cm in diameter has been developed. Despite the small diameter, this loudspeaker provides a large diaphragm displacement of /spl plusmn/8 mm, and therefore has superior bass sound reproduction characteristics.
Improved Skin Penetration Using In Situ Nanoparticulate Diclofenac Diethylamine in Hydrogel Systems: In Vitro and In Vivo Studies
Delivering diclofenac diethylamine transdermally by means of a hydrogel is an approach to reduce or avoid systemic toxicity of the drug while providing local action for a prolonged period. In the present investigation, a process was developed to produce nanosize particles (about 10 nm) of diclofenac diethylamine in situ during the development of hydrogel, using simple mixing technique. Hydrogel was developed with polyvinyl alcohol (PVA) (5.8% w/w) and carbopol 71G (1.5% w/w). The formulations were evaluated on the basis of field emission scanning electron microscopy, texture analysis, and the assessment of various physiochemical properties. Viscosity (163–165 cps for hydrogel containing microsize drug particles and 171–173 cps for hydrogel containing nanosize drug particles, respectively) and swelling index (varied between 0.62 and 0.68) data favor the hydrogels for satisfactory topical applications. The measured hardness of the different hydrogels was uniform indicating a uniform spreadability. Data of in vitro skin (cadaver) permeation for 10 h showed that the enhancement ratios of the flux of the formulation containing nanosize drug (without the permeation enhancer) were 9.72 and 1.30 compared to the formulation containing microsized drug and the marketed formulations, respectively. In vivo plasma level of the drug increased predominantly for the hydrogel containing nanosize drug-clusters. The study depicts a simple technique for preparing hydrogel containing nanosize diclofenac diethylamine particles in situ, which can be commercially viable. The study also shows the advantage of the experimental transdermal hydrogel with nanosize drug particles over the hydrogel with microsize drug particles.