快速学习英语超声波能提高生物燃料的生产率

海量资料下载 免费 学习英语 /xinlw.htm （申请网址）洛基国际英语 竭诚为您服务All chefs know that “you have to break some eggs to make an omelet（煎蛋卷）,“ and that includes engineers at Iowa State University who are using high-frequency sound waves to break down plant materials in order to cook up a better batch of biofuel. Research by David Grewell, associate professor of agricultural and biosystems engineering, and his colleagues Melissa Montalbo-Lomboy and Priyanka Chand, has shown that “pretreating“ a wide variety of feedstocks (including switch grass, corn stover, and soft wood) with ultrasound consistently enhances the chemical reactions necessary to convert the biomass into high-value fuels and chemicals. The team will present its findings at the 21st International Congress on Acoustics (ICA 2013), held June 2-7 in Montreal.In one example of ultrasounds positive impact on biofuel production, the Iowa State researchers found that they could significantly increase the efficiency of removing lignin（木质素） from biomass in solution. Lignin is the chemical compound that binds cellulose（纤维素） and hemicellulose（半纤维素） together in plant cell walls. Commonly, enzymes or chemicals are used to remove it from biomass and allow the freed sugars to be dissolved for further processing into biofuel. Grewell and his colleagues found that pretreating instead with ultrasound makes lignin removal so efficient that sugar dissolution occurs in minutes rather than the hours needed with traditional mixing systems.Grewells team also found that hydrolysis of corn starch could be greatly accelerated using ultrasonics. In a conventional ethanol plant, ground corn is steamed with jet cookers at boiling point temperatures. This breaks down the corn, leaving a starch mash that is then cooled and treated with enzymes in a process known as hydrolysis to release glucose forfermentation（发酵）. The Iowa State team replaced the initial steaming with ultrasound, sonically smashing the corn into tiny particles in the same way physicians use ultrasound to shatter kidney stones. The smaller corn fragments provided more surface area for enzymatic action, and therefore, resulted in fermentation yields comparable to jet cooking.The potential cost savings for this method, says Grewell, are very encouraging. “Economic models,“ he explains, “have shown that once implemented, this technology could have a payback period of less than one year.“Grewell and his colleagues report a third application for ultrasound in biofuel production, showing that they can accelerate transesterification, the main chemical reaction for converting oil to biodiesel. In one case, the researchers found that subjecting soybean oil to ultrasound transformed it into biodiesel in less than a minute, rather than the 45 minutes it normally takes. Similarly, Grewells team found that yeast populated with sugar and starved with glycerin, a co-product of biodiesel production, could prodfuce 海量资料下载 免费 学习英语 /xinlw.htm （申请网址）洛基国际英语 竭诚为您服务high yields of oil that could be extracted and simultaneously converted to biodiesel with ultrasonics in less than a minute. This is a dramatically faster and less complicated method than traditional techniques requiring multiple steps and relatively long cycle times.所有的厨师都知道，“你必须打破一些鸡蛋，煎蛋（煎蛋卷） “，而且包括在爱荷华州立大学的工程师正在使用高频声波为了编造一个更好的打破植物材料一批生物燃料。大卫 Grewell，农业和生物工程副教授，和他的同事梅利莎 Montalbo Lomboy 和普里昌德，研究表明， “预处理”超声一贯多种原料（包括柳枝稷，玉米秸秆，和软木材）增强要转换成高价值的生物质转化为燃料和化学品的化学反应。该小组将其研究结果提交第 21 届国际声学大会（含 2013 年）， 6 月 2-7 在蒙特利尔举行。超声波对生物燃料生产的积极影响的一个例子，爱荷华州立大学的研究人员发现，他们可以大大提高工作效率去除木质素（木质素）在溶液中的生物量。木质素的化学化合物，结合纤维素（纤维素），半纤维素（半纤维素）一起在植物细胞壁。通常，酶或化学品的使用，将其从生物量和允许被溶解释放的糖进一步加工成生物燃料。Grewell 和他的同事们发现，预处理，而不是用超声波使如此高效去除木质素，糖溶解发生在几分钟内，而不是与传统的混合系统所需的时间。Grewell 的研究小组还发现，玉米淀粉的水解可以大大加速使用超声波。在传统的乙醇生产厂，地里的玉米是在沸点温度下喷射电饭煲蒸。这打破了玉米，离开醪淀粉酶的过程称为水解释放葡萄糖发酵（发酵），然后将其冷却并用。衣阿华州立大学队取代了最初的热气腾腾的超声，声音粉碎成极小颗粒，玉米以同样的方式，医生用超声波粉碎肾结石。玉米的小的片段为酶的作用提供了更大的表面积，因此，导致与喷射蒸煮发酵产量。这种方法潜在的成本节约，说 Grewell，是非常令人鼓舞的。“经济模型，”他解释说，“ 已经表明，一旦实施，这项技术可以有一个投资回收期不到一年。”Grewell 和他的同事报告了第三个应用超声生物燃料的生产，表明他们可以加速酯交换反应，油转化生物柴油的主要化学反应。在一个案例中，研究人员发现，超声豆油转化成生物柴油，在不到一分钟，而不是 45 分钟，一般需要。同样，Grewell 的团队发现酵母人口糖和甘油饿