But his first two attempts on her behalf proved unproductive.
Mediation efforts led by Ugandan President Yoweri Museveni have so far proved unproductive.
Though his attempts proved unproductive, they stimulated him to explore the use of radioactive isotopes as tracers.
Christopher A. Viehbacher, Sanofi's chief executive, said on Monday that while he had met with Henri A. Termeer, his counterpart at Genzyme, for several hours last month, the talks proved unproductive.
Since the days of the Soviet Union, the Kremlin has been eager to exploit giant nonporous rock fields in western Siberia, but the fields have proved unproductive using conventional vertical drilling techniques.
The talks with Glasgow's Old Firm proved unproductive, Carter recalled, and the self-styled elite of English clubs – intent upon exerting greater influence and enjoying revenue to match – approached the Football Association about their ideas.
Frelimo's agricultural undertakings proved unproductive and unmanageable, however, and, in combination with the flight of South Asian merchants and the instability caused by guerrilla warfare, much of the country's agricultural production, commerce, and distribution system collapsed.
But this would not lower a company's rating unless the assets proved unproductive, because the formula measures trends over such a long period of time.
But these conventional methods proved unproductive due to their technical or economical constraints (Demir and Arisoy 2007; Cibati et al. 2013; Verma et al. 2015).
Observation of the Earth's surface proved unproductive, however, because of heavy cloud cover and bad photographic exposures.
Recording sessions initially proved unproductive due to Steven Adler's struggle with drug addiction, which made him unable to perform and caused sessions to abort for several days at a time.
