Google, upping the stakes in the mobile computing market wars with Apple and Amazon, has unveiled a sleeker version of its Nexus 7 tablet. The more powerful second-generation tablet comes with a high price; a 16-gigabyte version will cost $229, a $30 bump from the original Nexus 7 of a year ago but still below the $329 Apple Inc. asks for its comparable iPad Mini. A comparable Kindle Fire HD tablet from Amazon comes in under both at $199. The new Nexus 7, thinner lighter and more narrow than its predecessor, features a 7-inch display with a higher resolution than the original and a processor Google said would be nearly twice as fast. The display\'s 1,920 by 1,200 pixel resolution and a 323 pixel density is the highest of any tablet, Google said. The first device to run Google newest version of Android, 4.3, it also sports stereo speaker and battery life said to be an hour better. The new Nexus 7 devices will go on sale in the United States July 30, Google said at an announcement event in San Francisco Wednesday.