For products such as tobacco and junk food, where policy interventions are often designed to decrease consumption, affected consumers gain utility from improvements in lifetime health and longevity but also lose utility associated with the activity of consuming the product. In the case of anti-smoking policies, even though published estimates of gross health and longevity benefits are up to 900 times higher than the net consumer benefits suggested by a more direct willingness-to-pay estimation approach, there is little recognition in the cost-benefit and cost-effectiveness literature that gross estimates will overstate intrapersonal welfare improvements when utility losses are not netted out. This paper presents a general framework for analyzing policies that are designed to reduce inefficiently high consumption and provides a rule of thumb for the relationship between net and gross consumer welfare effects: where there exists a plausible estimate of the tax that would allow consumers to fully internalize health costs, the ratio of the tax to the per-unit long-term cost can provide an upper bound on the ratio of net to gross benefits.

Block copolymer directed self‐assembly (BCP) with chemical epitaxy is a promising lithographic solution for patterning features with critical dimensions under 20 nm. In this work, we study the extent to which lamellae‐forming poly(styrene‐b‐methyl methacrylate) can be directed with chemical contrast patterns when the pitch of the block copolymer is slightly compressed or stretched compared to the equilibrium pitch observed in unpatterned films. Critical dimension small angle X‐ray scattering complemented with SEM analysis was used to quantify the shape and roughness of the line/space features. It was found that the BCP was more lenient to pitch compression than to pitch stretching, tolerating at least 4.9% pitch compression, but only 2.5% pitch stretching before disrupting into dislocation or disclination defects. The more tolerant range of pitch compression is explained by considering the change in free energy with template mismatch, which suggests a larger penalty for pitch stretching than compressing. Additionally, the effect of width mismatch between chemical contrast pattern and BCP is considered for two different pattern transfer techniques. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 595–603

Engineering the thermal conductivity of amorphous materials is highly essential for the thermal management of future electronic devices. Here, we demonstrate the impact of ultrafine nanostructuring on the thermal conductivity reduction of amorphous silicon nitride (a-Si3N4) thin films, in which the thermal transport is inherently impeded by the atomic disorders. Ultrafine nanostructuring with feature sizes below 20 nm allows us to fully suppress contribution of the propagating vibrational modes (propagons), leaving only the diffusive vibrational modes (diffusons) to contribute to thermal transport in a-Si3N4. A combination of the phonon-gas kinetics model and the Allen-Feldmann theory reproduced the measured results without any fitting parameters. The thermal conductivity reduction was explained as extremely strong diffusive boundary scattering of both propagons and diffusons. These findings give rise to substantial tunability of thermal conductivity of amorphous materials, which enables us to provide better thermal solutions in microelectronic devices.

Studies have demonstrated that the thermal conductivity (κ) of crystalline semiconductor materials can be reduced by phonon scattering in periodic nanostructures formed using templates fabricated from self-assembled block copolymers (BCPs). Compared to crystalline materials, the heat transport mechanisms in amorphous inorganic materials differ significantly and have been explored far less extensively. However, thermal management of amorphous inorganic solids is crucial for a broad range of semiconductor devices. Here we present the fabrication of freestanding amorphous silicon nitride (SiN x ) membranes for studying κ in an amorphous solid. To form a periodic nanostructure, directed self-assembly of cylinder-forming BCPs is used to pattern in the SiN x highly ordered, hexagonally close packed nanopores with pitch and neck width down to 37.5 and 12 nm, respectively. The κ of the nanoporous SiN x membranes is 60% smaller than the classically predicted value based on just the membrane porosity. In comparison, holes with much larger neck widths and pitches patterned by e-beam lithography lead to only a slight reduction in κ, which is closer to the classical porosity-based prediction. These results demonstrate that κ of amorphous SiN x can be reduced by introducing periodic nanostructures that behave as a phononic crystal, where the relationship between the smallest dimension of the nanostructure and the length scale of the mean-free paths of the dominant, heat-carrying phonons is critical. Additionally, changing the orientation of the hexagonal array of nanopores relative to the primary direction of heat flow has a smaller impact on amorphous SiN x than was previously observed in silicon.