Simulation study of the effect of molar mass dispersity on domain interfacial roughness in lamellae forming block copolymers for directed self-assembly.

A coarse-grained molecular dynamics model was used to study the thin film self-assembly and resulting pattern properties of block copolymer (BCP) systems with various molar mass dispersities. Diblock copolymers (i.e. A-b-B type) were simulated in an aligned lamellar state, which is one of the most common patterns of potential use for integrated circuit fabrication via directed self-assembly of BCPs. Effects of the molar mass dispersity (Ð) on feature pitch and interfacial roughness, which are critical lithographic parameters that have a direct impact on integrated circuit performance, were simulated. It was found that for a realistic distribution of polymer molecular weights, modeled by a Wesslau distribution, both line edge roughness (LER) and line width roughness (LWR) increase approximately linearly with increasing Ð, up to ∼45% of the monodisperse value at Р= 1.5. Mechanisms of compensation for increased A-A and B-B roughness were considered. It was found that long and short chain positions were not correlated, and that long chains were significantly deformed in shape. The increase in LWR was due to the increase in LER and a constant correlation between the line edges. Unaligned systems show a correlation between domain width and local molecular weight, while systems aligned on an alternating pattern of A and B lines did not show any correlation. When the volume fraction of individual chains was allowed to vary, similar results were found when considering the Ð of the block as opposed to the Ð of the entire system.

Creating graphene p-n junctions using self-assembled monolayers.

3-Aminopropyltriethoxysilane (APTES) and perfluorooctyltriethoxysilane (PFES) were used to modify the interface between transferred CVD graphene films and its supporting dielectric to create n-type and p-type graphene, respectively. A graphene p-n junction was obtained by patterning both modifiers on the same dielectric and verified through the creation of a field effect transistor (FET). Characteristic I-V curves indicate the presence of two separate Dirac points which confirms an energy separation of neutrality points within the complementary regions. This method minimizes doping-induced defects and results in thermally stable graphene p-n junctions for temperatures up to 200 °C.

Drug-induced subacute cutaneous lupus erythematosus: a paradigm for bedside-to-bench patient-oriented translational clinical investigation.

At least 71 patients have been reported in which their otherwise typical subacute cutaneous lupus erythematosus (SCLE) skin lesions were felt to have been temporally associated with the systemic administration of a drug. The mean age of this cohort of drug-induced SCLE (DI-SCLE) patients was 59 years of age which is somewhat older than the mean age of previously reported idiopathic SCLE patient cohorts. Patients had been taking the suspected triggering drug for weeks to years before the onset of SCLE skin lesions. In addition, it was not unusual for 2-3 months to be required for resolution of the SCLE skin lesions following discontinuation of the triggering drug. A relatively large number of drugs representing different pharmacological classes have been implicated in the induction of SCLE. The drug classes that were more frequently encountered were those used for the treatment of cardiovascular disease, especially hypertension. Calcium channel blockers were especially common in this regard. Elderly individuals being treated for hypertension are often taking multiple classes of drugs that have been implicated in triggering SCLE (thiazide diuretics, calcium channel blockers, angiotensin converting enzyme (ACE) inhibitors, beta-blockers). An approach to the management of DI-SCLE is presented. Ro/SS-A autoantibodies tended to remain present in the blood after resolution of drug-induced SCLE skin lesions. A common link between the disparate group of drug structures implicated in triggering SCLE is their tendencies to produce photosensitivity and lichenoid drug reactions. This leads to the speculation that DI-SCLE could represent a photo-induced isomorphic/Köebner response in an immunogenetically predisposed host.

Sarcoidal alopecia as a mimic of discoid lupus erythematosus.

Cicatricial alopecia presents a diagnostic challenge to clinicians. In particular, lesions of cutaneous sarcoidosis of the scalp may resemble discoid lupus erythematosus (DLE). We report two cases of sarcoidal alopecia originally thought to represent DLE scarring plaques of the scalp. A subsequent histopathologic diagnosis of sarcoidal alopecia was made. These cases highlight the importance of making the correct diagnosis of sarcoidal alopecia versus DLE so that a patient can receive the correct work-up and definitive treatment. These cases illustrate the fact that there should be a low threshold for biopsy of cicatricial plaques on the scalp.