5 resultados para press forming

em Bucknell University Digital Commons - Pensilvania - USA


Relevância:

20.00% 20.00%

Publicador:

Resumo:

The Gaussian-2, Gaussian-3, complete basis set- (CBS-) QB3, and CBS-APNO methods have been used to calculate ΔH° and ΔG° values for neutral clusters of water, (H2O)n, where n = 2−6. The structures are similar to those determined from experiment and from previous high-level calculations. The thermodynamic calculations by the G2, G3, and CBS-APNO methods compare well against the estimated MP2(CBS) limit. The cyclic pentamer and hexamer structures release the most heat per hydrogen bond formed of any of the clusters. While the cage and prism forms of the hexamer are the lowest energy structures at very low temperatures, as temperature is increased the cyclic structure is favored. The free energies of cluster formation at different temperatures reveal interesting insights, the most striking being that the cyclic trimer, cyclic tetramer, and cyclic pentamer, like the dimer, should be detectable in the lower troposphere. We predict water dimer concentrations of 9 × 1014 molecules/cm3, water trimer concentrations of 2.6 × 1012 molecules/cm3, tetramer concentrations of approximately 5.8 × 1011 molecules/cm3, and pentamer concentrations of approximately 3.5 × 1010 molecules/cm3 in saturated air at 298 K. These results have important implications for understanding the gas-phase chemistry of the lower troposphere.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Solo Exhibition of prints and drawings at The Ink Shop Olive Branch Press in Ithaca, New York November 2012-January 2013

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Nettie Honeyball and Florence Dixie founded the British Ladies Football Club (BLFC) in 1894 with the aim to provide football-playing opportunities for girls and young women, but also as a means of making money. Theirs, in effect, was an attempt to create a professional football league for women. Public interest in 'the lady footballers' was enormous, at least in its early stages, and generated considerable attention from the press. Overall, press coverage of the BLFC was negative (football is a man's sport; football is a working-class sport; women are physically incapable of playing the game; women shouldn't appear publicly in bifurcated garments, etc.), with only a few notable exceptions. Did the stance adopted depend on the political leaning of the newspaper? Or were the reporters simply reflecting the social and economic realities of their time, struggling to 'explain' a marginal group - women athletes, or more specifically, middle-class women football players - engaging in a working-class male game? This article examines the press coverage of the BLFC. The double standard evident in the newspaper coverage was, on the surface, as one might expect: if a woman played well, she was a freak, possibly a man in disguise; if she didn't play well, it proved that women shouldn't play football. But on closer examination, the double standard was actually rather nuanced: if she played well and looked the part of a woman, she could be subject to praise; yet if she played well and didn't conform to the standard of feminine beauty, she faced ridicule, and her gender called into question.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

ABSTRACT FOR PART I: PHOSPHA-MICHAEL ADDITIONS TO ACTIVATED INTERNAL ALKENES: STERIC AND ELECTRONIC EFFECTS A method for the phospha-Michael addition of bis(4-methyl)phenyl phosphine oxide to activated internal alkenes has been developed. Michael acceptors including cinnamates, crotonates, chalcones, and internal alkenes containing multiple activating groups were all successfully utilized in this reaction. The reaction was fairly tolerant of electron-donating and electron-withdrawing substituents on the Michael acceptor, and moderate to excellent yields (49-96%) of the adducts were isolated. When steric bulk was increased by a second substituent on the -position of the Michael-acceptor the reaction was suppressed. This was usually overcome by adding a second activating substituent to the -position. ABSTRACT FOR PART II: MICROWAVE-ASSISTED ARYLGOLD BOND FORMATION A microwave-assisted method was developed for the formation of arylgold complexes containing (2-Biphenyl)di-tert-butylphosphine (JohnPhos) as the supporting phosphine ligand. Arylboronic acids with increasingly bulky aromatic groups were screened to determine the steric limitations of the reaction. Arylgold complexes (JohnPhos)Au(p-methoxyphenyl), (JohnPhos)Au(2,4,6-trimethylphenyl), and (JohnPhos)Au(4-bromo-10-anthracene) were all synthesized by microwave irradiation at 70ºC in the presence of Cs2CO3 in either THF or iPrOH. Reactions performed with arylboronic acids containing unhindered ortho positions were carried out in THF. Arylboronic acids with substituents on the ortho position required iPrOH as the reaction solvent. Arylboronic acids with extreme steric hindrance on the ortho position of the aryl substituent, 2,4,6-triisopropylpphenylboronic acid, were unreactive. It was determined that increasing the irradiation temperature increased the formation of side products, therefore to promote conversion to the arylgold complex the duration of the reaction time was increased while maintaining a temperature of 70ºC. Arylgold complexes (JohnPhos)Au(p-methoxyphenyl), (JohnPhos)Au(2,4,6-trimethylphenyl), and (JohnPhos)Au(4-bromo-10-anthracene) were synthesized with moderate yields (40-69%).