Microfluidic devices, which consist of networks of channels with micrometer dimensions, have attracted considerable attention in a wide range of applications including analytical systems, biomedical devices, and as tools for chemistry and biochemistry based experiments 1 5 . These devices can produce monodisperse droplets with exceptional precision, which are useful as individual compartments for chemical reactions and templates for preparation of monodisperse functional particles 6 11 . To date, several types of microfluidic devices have been developed. For example, capillary microfluidic devices consist of coaxial assemblies of tapered glass capillaries on glass slides 12,13 .Although the device can be fabricated at low cost, it is cumbersome to set the positions and sizes of the capillaries precisely. There are also polydimethylsiloxane PDMS devices, which consist of patterned microchannels in a silicone elastomer of PDMS fabricated by soft lithography techniques 14 16 . Although using soft lithography facilitates accurate control of the positions and sizes of the channels in the device through the design of mask patterns, it is difficult to fabricate flow channels in three dimensions, which would limit the utility of the device for many applications. 21 , could be prepared by polymerization of a gelation reagent dissolved in the monodisperse water droplets. Although stereolithography is a promising method for fabricating three-dimensional microfluidic devices, the default properties of the resin are inappropriate for many applications. For example, the device cannot produce oilin-water O/W emulsions and double emulsions, consisting of drops of oil and water assembled into a core-shell structure, owing to the hydrophobic surface properties of the flow channels 22,23 . To broaden the applicability of the devices, control of the wetting characteristics of the surface of channels is necessary. In this paper, we report on the surface treatment of the NOTE Abstract: A microfluidic device with three-dimensional flow channels was fabricated by stereolithography, and hydrophilic surface treatment of the flow channel was performed by coating the wall of the channel with a silica layer. After the treatment, the device produced monodisperse oil-in-water (O/W) emulsions. The silica layer on the channel surface was then coated with a fluorinated silane coupling agent to make it hydrophobic, thus enabling the treated device to produce monodisperse inverted water-in-oil (W/O) emulsions.

Karyotypes and reproductive isolation were studied in two allopatric populations of Drosophila tsigana, one from Guizhou Province in southern China and the other from Hokkaido in northern Japan, and in one population of a closely related species, D. longiserrata, from Guizhou. In metaphase plates of larval brain cells, both geographic strains of Drosophila tsigana showed 2n=10 chromosomes, with 2 pairs of metacentric (V-shape), 2 pairs of acrocentric (R-shape), and 1 pair of dot-liked (D-shape) chromosomes. Drosophila longiserrata showed the same number, 10 chromosomes, comprising 2V, 1J (sub-metacentric chromosome), 1R, and 1D. X chromosomes of both species were acrocentric, the presumed ancestral form. Premating isolation was complete between D. tsigana and D. longiserrata, and successful mating was also limited in crosses between the two geographic populations of D. tsigana, especially in crosses between Japanese (JP) females and Guizhou (GZ) males. F1 hybrids were obtained only from crosses between GZ females and JP males, and fertilities of both F1 females and males were quite incomplete. The results of morphological observations, karyotypic analyses, and crossing experiments clearly showed that the GZ and JP populations of "D. tsigana" were highly divergent from each other and that each population should be recognized as a biologically valid species. The present morphological observations and chromosomal analyses, together with the original descriptions, strongly suggest that "Guizhou D. tsigana" might be conspecific with D. bisetata Toda, 1988 from Myanmar, and that D. longiserrata might be conspecific with D. afer Tan, Hsu, and Sheng, 1949 from Meitan, Guizhou.

A microfluidic device with three-dimensional flow channels is fabricated by stereolithography according to a computer-aided design (CAD) model. By injecting water and oil phases into the device, a monodisperse water-in-oil emulsion is formed. We show that monodisperse thermosensitive poly(N-isopropylacrylamide) gel particles can be prepared by photopolymerization of a gelation reagent dissolved in the water phase.

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