Thinking about sprouting at home? MOM’s Organic Market sells home sprouters, and seeds and sprouters are available via online retailers such as Sproutpeople and Sproutman. Gil Frishman and Lori Tooker, who run Sproutpeople, keep their site stocked with tips for home sprouters, particularly when it comes to avoiding mold and bacteria. In general, sterilize your equipment, rinse and drain well, and be sure the water you use is no warmer than 60 to 70 degrees Fahrenheit, unless otherwise specified for a particular seed.
Fresh sprouts generally keep for a week in the refrigerator, but be mindful of “best by” dates if sourcing at the supermarket. Shelf-stable sprouted grains such as quinoa and rice will keep in the pantry for one year. Sprouted flours will keep in airtight containers for six months at room temperature. To extend their shelf life up to one year, freeze.
Fresh-baked sprouted flour bread can develop mold after four days or so. Peter Reinhart suggests pre-slicing, wrapping in film or a plastic bag, and then freezing to extend the shelf life.
2011年6月14日星期二
2011年4月26日星期二
Machining Injection Molds with Ultrashort Laser Pulses
Systems for homogeneous LED lighting have in the past used a large number of LEDs and optical diffuser panels for distributing the high spot-luminance. As an alternative, ever compacter optical waveguides, adjusted to the lighting requirements, are increasingly being used, in which the light is diverted and distributed with refractive outcoupling by roughening or structuring. Refractive light outcoupling is performed with microlens arrays. Such an array may consist of several hundred thousand microlenses with geometries in the micrometer range. Producing such structures by injection molding requires a high, uniform quality. It is determined by the precision of the molds.
At the Fraunhofer-Institute of Laser Technology (ILT) Aachen, Germany, injection molds were machined with ultrashort laser pulses. This could significantly improve the process. New, industrial ultrashort pulse lasers reduce machining times to a few hours, compared with conventional methods, which take at least a week. Moreover, the ultrashort pulse lasers permit high precision for machining steel molds. The picosecond laser pulses are about a thousand times shorter than a conventional quality-switched solid-state laser, like that used, e.g., for marking. While melt expulsion still occurs with conventional lasers, the ultrashort pulse laser evaporates the material with high precision and no residues. Subsequent laser polishing permits a smooth and uniform surface on the molds down to the submicrometer range (Ra > 100 nm).
For the tests, commercial systems with a focus diameter of 20 µm, several 10 µJ of pulse energy and a repetition rate of >100 kHz were used. The mold insert microstructure generated by laser texturing has depressions with a diameter of 50 µm and more. While commercial systems have so far only been available in the range below 100 W, prototypes of over 1,000 W average output have already been developed at the Fraunhofer ILT.
At the Fraunhofer-Institute of Laser Technology (ILT) Aachen, Germany, injection molds were machined with ultrashort laser pulses. This could significantly improve the process. New, industrial ultrashort pulse lasers reduce machining times to a few hours, compared with conventional methods, which take at least a week. Moreover, the ultrashort pulse lasers permit high precision for machining steel molds. The picosecond laser pulses are about a thousand times shorter than a conventional quality-switched solid-state laser, like that used, e.g., for marking. While melt expulsion still occurs with conventional lasers, the ultrashort pulse laser evaporates the material with high precision and no residues. Subsequent laser polishing permits a smooth and uniform surface on the molds down to the submicrometer range (Ra > 100 nm).
For the tests, commercial systems with a focus diameter of 20 µm, several 10 µJ of pulse energy and a repetition rate of >100 kHz were used. The mold insert microstructure generated by laser texturing has depressions with a diameter of 50 µm and more. While commercial systems have so far only been available in the range below 100 W, prototypes of over 1,000 W average output have already been developed at the Fraunhofer ILT.
订阅：
博文 (Atom)