We report a simple process to solubilize high weight fraction single-wall carbon nanotubes in water by the nonspecific physical adsorption of sodium dodecylbenzene sulfonate. The diameter distribution of nanotubes in the dispersion, measured by atomic force microscopy, showed that even at 20 mg/mL ∼63 ± 5% of single-wall carbon nanotube bundles exfoliated into single tubes. A measure of the length distribution of the nanotubes showed that our dispersion technique reduced nanotube fragmentation.

This paper analyzes the impact of student loans for higher education on enrollment, dropout decisions, and earnings. We investigate the massive State Guaranteed Loan (SGL) program implemented in Chile in 2006. Our empirical analysis is based on the estimation of a sequential schooling decision model with unobserved heterogeneity. We supplement this model with labor market outcomes. The model is estimated using rich longitudinal data generated from administrative records.Our findings show that the SGL program increased the probability of enrollment and reduced the probability of dropping out from tertiary education: SGL reduced the first year dropout rate by 6.8% for students enrolled in five-year colleges and by 64.3% for those enrolled in institutions offering twoor four-year degrees. Moreover, we document that the SGL program has been more effective in reducing the probability of dropping out for low-skilled individuals from low-income families. When analyzing labor market outcomes, we find that SGL beneficiaries have lower wages (up to 6.4% less) than those who did not "benefit'' from the program. We attribute this negative result to the design of the SGL program, which has incentivized higher education institutions to retain students at the expense of not securing the quality of education

"Liability dollarization,'' namely intermediation of capital inflows in units of tradables into domestic loans in units of aggregate consumption, adds three important effects driven by realexchange-rate fluctuations that alter standard models of Sudden Stops significantly: Changes on the debt repayment burden, on the price of new debt, and on a risk-taking incentive (i.e. a negative premium on domestic debt). Under perfect foresight, the first effect makes Sudden Stops milder and multiple equilibria harder to obtain. The three effects add an ``intermediation externality'' to the macroprudential externality of standard models, which is present even without credit constraints. Optimal policy under commitment can be decentralized equally by taxing domestic credit or capital inflows, and hence capital controls as a separate instrument are not justified. This optimal policy is time-inconsistent and follows a complex, non-linear schedule. Quantitatively, an optimized pair of constant taxes on domestic debt and capital inflows makes crises slightly less likely and yields a small welfare gain, but other pairs reduce welfare sharply. For high effective debt taxes, capital controls and domestic debt taxes are again equivalent, and for low ones welfare is higher with higher taxes on domestic debt than on capital inflows.

No abstract