Sonochemistry: the ultrasound and the fury.
Sonochemistry: The ultrasound and the fury
The scene is downright hellish: Millions of tiny gas bubbles continuously form, grow and implode To link component pieces to a major assembly. It may also refer to compressing data using a particular technique. Contrast with explode. with such rapidity and force that their contents reach temperatures common at the sun's surface. Shock waves radiating from the miniature depth-charges create localized pressures approaching those of the deepest ocean trench. Hieronymus Bosch Noun 1. Hieronymus Bosch - Dutch painter (1450-1516)
Bosch, Jerom Bos would have loved it.
Chemists Kenneth S. Suslick and Stephen J. Doktycz do. Working at the University of Illinois University of Illinois may refer to:
In the March 2 SCIENCE, Suslick and Doktycz report some details underlying these swift "sonochemical" reactions. "This set of experiments allowed us for the first time to get at least a rough feeling for the conditions that occur when ultrasound irradiates a liquid containing solid powder," Suslick told SCIENCE NEWS.
The ultrasonic shock waves force particles to collide, much as a huge ocean wave might smash two surfers together. By examining fine dissolved particles of transition metals--zinc, tin, nickel, chromium, tungsten and others, which collide and can melt together during ultrasonic irradiation -- the researchers have inferred just how fast and hot particle collisions can get.
Tiny metallic "necks" that bridge the fused particles provide the empirical clue for reconstructing the unseen collisions. A neck's volume, ranging from about one-half of six-trillionths of a cubic centimeter cu·bic centimeter
Abbr. cc A unit of volume equal to one thousandth (10-3) of a liter or to one milliliter. , indicates how much metal melts during the collisions and therefore how much energy is needed to drive the melting process. Presumably pre·sum·a·ble
That can be presumed or taken for granted; reasonable as a supposition: presumable causes of the disaster. the particles carried this energy into the collisions in the form of kinetic energy kinetic energy: see energy.
Form of energy that an object has by reason of its motion. The kind of motion may be translation (motion along a path from one place to another), rotation about an axis, vibration, or any combination of . The researchers calculate that particles with diameters in the 5-to-10-micron range attain velocities ranging from 100 to 500 meters per second.
They also found that metals with melting temperatures below molybdenum's 2,617 [degrees]C form well-defined necks, while tungsten particles, which melt at 3,410 [degrees]C show no signs of fusing. Collisions between molybdenum molybdenum (məlĭb`dənəm) [Gr.,=leadlike], metallic chemical element; symbol Mo; at. no. 42; at. wt. 95.94; m.p. about 2,617°C;; b.p. about 4,612°C;; sp. gr. 10.22 at 20°C;; valence +2, +3, +4, +5, or +6. particles result in less-pronounced links, which the researchers describe as "spot welds." They conclude that peak temperatures during interparticle collisions fall between 2,600 [degrees]C and 3,400 [degrees]C and that some of the molten necks must cool at rates of more than 1 billion [degrees]C per second, since the particles would otherwise separate as they recoil recoil /re·coil/ (re´koil) a quick pulling back.
elastic recoil the ability of a stretched object or organ, such as the bladder, to return to its resting position. after the collision.
Such findings should help scientists uncover the mechanisms by which ultrasound enhances the catalytic power of metal particles, says sonochemist Philip Boudjouk of North Dakota State University North Dakota State University, at Fargo; land-grant and state supported; coeducational; chartered and opened 1890 as North Dakota Agricultural College, achieved university status in 1960. in Fargo.