The electronic structures of two-dimensional materials are strongly dependent on their thicknesses; for example, there is an indirect to direct band gap transition from multilayer to single-layer MoS2. A simple, efficient, and nondestructive way to control the thickness of MoS2 is highly desirable for the study of thickness-dependent properties as well as for applications. Here, we present layer-by-layer thinning of MoS2 nanosheets down to monolayer by using Ar(+) plasma. Atomic force microscopy, high-resolution transmission electron microscopy, optical contrast, Raman, and photoluminescence spectra suggest that the top layer MoS2 is totally removed by plasma while the bottom layer remains almost unaffected. The evolution of Raman and photoluminescence spectra of MoS2 with thickness change is also investigated. Finally, we demonstrate that this method can be used to prepare two-dimensional heterostructures with periodical single-layer and bilayer MoS2. The plasma thinning of MoS2 is very reliable (with almost 100% success rate), can be easily scaled up, and is compatible with standard semiconductor process to generate heterostructures/patterns at nanometer scale, which may bring out interesting properties and new physics.

The content validity ratio (Lawshe) is one of the earliest and most widely used methods for quantifying content validity. To correct and expand the table, critical values in unit steps and at multiple alpha levels were computed. Implications for content validation are discussed.

Patients with diabetes must incorporate a complicated regimen of self-management into their daily lives (e.g., taking medication, diet, exercise). Diabetes self-management (DSM) is the cornerstone for controlling diabetes and preventing diabetic complications. The purpose of this study was to test a model describing the effects of individual and environmental factors on DSM in a sample of patients with diabetes in Beijing, China. Survey data were gathered from a convenience sample of 201 Chinese adults with type 2 diabetes during outpatient visits. Data were analyzed using structural equation modeling. Model fit indices indicated a good fit to the data. In the final model, belief in treatment effectiveness and diabetes self-efficacy were proximate factors affecting DSM. Knowledge, social support, and provider-patient communication affected self-management indirectly via beliefs and self-efficacy. The findings provide a theoretical basis to direct the development of interventions for improving DSM in Chinese individuals with diabetes.