On the origin of the extremely different solubilities of polyethers in water

The solubilities of polyethers are surprisingly counter-intuitive. The best-known example is the difference between polyethylene glycol ([–CH2–CH2–O–]n) which is infinitely soluble, and polyoxymethylene ([–CH2–O–]n) which is completely insoluble in water, exactly the opposite of what one expects from the C/O ratios of these molecules. Similar anomalies exist for oligomeric and cyclic polyethers. To solve this apparent mystery, we use femtosecond vibrational and GHz dielectric spectroscopy with complementary ab initio calculations and molecular dynamics simulations. We find that the dynamics of water molecules solvating polyethers is fundamentally different depending on their C/O composition. The ab initio calculations and simulations show that this is not because of steric effects (as is commonly believed), but because the partial charge on the O atoms depends on the number of C atoms by which they are separated. Our results thus show that inductive effects can have a major impact on aqueous solubilities

A voltage-tunable three-terminal Gunn device

Newly developed Gunn oscillator is three-terminal device which consists of piece of gallium arsenide with source, drain, and gate contacts. Voltage tunable three-terminal device does not require bulky resonant cavity and allows oscillation frequency to be rapidly tuned with simple circuitry

Transparent polymeric laminates

Laminate prepared from epoxy-boroxine and phenolphthalein polycarbonate has high mechanical strength at elevated temperature and is resistant to impact, fire, and high-energy thermal radiation. Polycarbonate is prepared by reaction of phenolphthalein with phosgene in presence of amine catalyst and immiscible organic solvent phase

Do In-State Tuition Benefits Affect the Enrollment of Non-Citizens? Evidence from Universities in Texas

In 2001, the Texas state legislature passed House Bill 1403 and became the first state to offer in-state tuition rates at public universities for non-citizens who attended high school in the state for three years. As a result of the policy change, the cost of attending college at public universities in Texas fell dramatically for non-citizens. Using administrative data from six universities in Texas, we employ a quasi-experimental design to identify the effects of the policy change on the probability of enrollment. The results demonstrate a large and significant positive effect of lowering tuition on the enrollment of non-citizens at the University of Texas at Pan American and a positive and marginally significant effect on the probability of enrollment at the University of Texas at San Antonio. The results also suggest that the policy had a negative effect on enrollment at Southern Methodist University, a private university whose tuition was unchanged by the policy.financial aid; non-citizens; in-state tuition benefits.