How to make water run uphill

A surface having a spatial gradient in its surface free energy was capable of causing drops of water placed on it to move uphill. This motion was the result of an imbalance in the forces due to surface tension acting on the liquid-solid contact line on the two opposite sides ("uphill" or "downhill") of the drop. The required gradient in surface free energy was generated on the surface of a polished silicon wafer by exposing it to the diffusing front of a vapor of decyltrichlorosilane, Cl(3)Si(CH(2))(9)CH(3). The resulting surface displayed a gradient of hydrophobicity (with the contact angle of water changing from 97 degrees to 25 degrees ) over a distance of 1 centimeter. When the wafer was tilted from the horizontal plane by 15 degrees , with the hydrophobic end lower than the hydrophilic, and a drop of water (1 to 2 microliters) was placed at the hydrophobic end, the drop moved toward the hydrophilic end with an average velocity of approximately 1 to 2 millimeters per second. In order for the drop to move, the hysteresis in contact angle on the surface had to be low (相似文献   

Council of U.S. Academy of Sciences Expresses Concern to Soviet Counterparts over Sakharov Harrassment

National Academy of Sciences (NAS) president Philip Handler has made public a cable to his opposite number in the Soviet Union expressing the "deep concern" of the NAS Council for the welfare of dissenting Soviet physicist Andrei Sakharov and warning that, if further measures were taken against Sakharov, "it would be extremely difficult to imagine successful fulfillment of American pledges of binational scientific cooperation . . . ." Handler's message is the strongest public expression to date of NAS concern over treatment of Soviet scientists and other intellectuals (Science, 6 April). The cable, addressed to M. V. Keldysh, president of the Soviet Academy of Sciences, is given in full below.     

团结务实开拓创新努力办好农业广播电视教育

津南区农广校开展多层次、多形式、多渠道的学历教育和技术培训，主要方法是：一在全市首家加挂“津南区农民科技教育培训中心”的牌子，全面承担政府对农民实施科技教育培训职能；二是加强队伍建设，提高管理水平。三是承担“跨世纪青年农民科技培训工程”项目，措施得当、效果突出。同时紧紧抓住产业结构调整及农民需要这条主线，采用技术推动模式、政策推动模式、园区推动模式、示范户推动模式和信息推动模式等5种培训模式，以点带面，有效地促进了“培训”工作的深入开展。     

Oak leaf quality declines in response to defoliation by gypsy moth larvae

Leaves of red oak trees that had been defoliated by gypsy moth larvae during the previous year and again during the period of the study had higher values of tanning coefficients, total phenolics, hydrolyzable and condensed tannins, dry matter contents, and toughness than did leaves of undamaged trees. These changes may influence larval growth and alter the course of further outbreaks.