Chemical Conversions within the Mo-Ga-C System: Layered Solids with Variable Ga Content.

Layered carbides are fascinating compounds due to their enormous structural and chemical diversity, as well as their potential to possess useful and tunable functional properties. Their preparation, however, is challenging and forces synthesis scientists to develop creative and innovative strategies to access high-quality materials. One unique compound among carbides is Mo2Ga2C. Its structure is related to the large and steadily growing family of 211 MAX phases that crystallize in a hexagonal structure (space group P63/mmc) with alternating layers of edge-sharing M6X octahedra and layers of the A-element. Mo2Ga2C also crystallizes in the same space group, with the difference that the A-element layer is occupied by two A-elements, here Ga, that sit right on top of each other (hence named "221" compound). Here, we propose that the Ga content in this compound is variable between 2:2, 2:1, and 2: ≤1 (and 2:0) Mo/Ga ratios. We demonstrate that one Ga layer can be selectively removed from Mo2Ga2C without jeopardizing the hexagonal P63/mmc structure. This is realized by chemical treatment of the 221 phase Mo2Ga2C with a Lewis acid, leading to the "conventional" 211 MAX phase Mo2GaC. Upon further reaction with CuCl2, more Ga is removed and replaced with Cu (instead of fully exfoliating into the Ga-free Mo2CTx MXene), leading to Mo2Ga1-xCuxC still crystallizing with space group P63/mmc, however, with a significantly larger c-lattice parameter. Furthermore, 211 Mo2GaC can be reacted with Ga to recover the initial 221 Mo2Ga2C. All three reaction pathways have not been reported previously and are supported by powder X-ray diffraction (PXRD), electron microscopy, X-ray spectroscopy, and density functional theory (DFT) calculations.

An Updated Review of Pemphigus Diseases.

Clinicians may encounter a variety of skin conditions that present with vesiculobullous lesions in their everyday practice. Pemphigus vulgaris, pemphigus foliaceus, IgA pemphigus, and paraneoplastic pemphigus represent the spectrum of autoimmune bullous dermatoses of the pemphigus family. The pemphigus family of diseases is characterized by significant morbidity and mortality. Considering the risks associated with a delayed diagnosis or misdiagnosis and the potential for overlap in clinical features and treatment, evaluation for suspected pemphigus disease often requires thorough clinical assessment and laboratory testing. Diagnosis is focused on individual biopsies for histopathology and direct immunofluorescence. Additional laboratory methods used for diagnosis include indirect immunofluorescence and enzyme-linked immunosorbent assay. Recent advancements, including anti-CD20 therapy, have improved the efficacy and reduced the morbidity of pemphigus treatment. This contribution presents updates on the pathophysiology, clinical features, diagnostic work-up, and medical management of pemphigus. Improved strategies for diagnosis and clinical assessment are reviewed, and newer treatment options are discussed.

Experimental and theoretical investigation of the chemical exfoliation of Cr-based MAX phase particles.

Two-dimensional carbides/nitrides, typically called MXenes, are an emerging member of the ever-growing family of two-dimensional materials. The prediction of a ferromagnetic groundstate in chromium-containing MXenes has triggered growing interest in their chemical exfoliation from Cr-based MAX phases. However, the exfoliation poses serious difficulties using standard etching agents such as hydrofluoric acid (HF). Here, we investigate the exfoliability of Cr2GaC particles by chemical etching with aqueous HF both experimentally and theoretically. Structural and microstructural analyses show that the Cr2GaC particles decompose into chromium carbide and oxide without the formation of a Cr-based MXene. A thermodynamic analysis based on ab initio electronic structure calculations reveals that the exfoliation of Cr-based MXene from Cr2GaC by HF-etching is inhibited by more favorable competing reactions. This result confirms the experimental finding and suggests that HF is an unsuitable etching agent for a successful exfoliation of Cr2GaC.

Considerations of Privacy and Confidentiality in Developing a Clinical Support Tool for Adolescent Tobacco Prevention: Qualitative Study.

BACKGROUND: Electronic clinical support tools show promise for facilitating tobacco screening and counseling in adolescent well-care. However, the application of support tools in pediatric settings has not been thoroughly studied. Successfully implementing support tools in local settings requires an understanding of barriers and facilitators from the perspective of both patients and providers. OBJECTIVE: This paper aimed to present the findings of a qualitative study conducted to inform the development and implementation of a support tool for adolescent tobacco screening and counseling in 3 pediatric clinics in North Florida. The primary objective of the study was to test and collect information needed to refine a tablet-based support tool with input from patients and providers in the study clinics. METHODS: A tablet prototype was designed to collect information from adolescents on tobacco susceptibility and use before their well-care visit and to present tobacco prevention videos based on their responses. Information collected from adolescents by the support tool would be available to providers during the visit to facilitate and streamline tobacco use assessment and counseling components of well-care. Focus groups with providers and staff from 3 pediatric clinics (n=24) identified barriers and facilitators to implementation of the support tool. In-depth interviews with racially and ethnically diverse adolescent patients who screened as susceptible to tobacco use (n=16) focused on acceptability and usability of the tool. All focus groups and interviews were audio-recorded and transcribed for team-based coding using thematic analysis. RESULTS: Privacy and confidentiality of information was a salient theme. Both groups expressed concerns that the tool's audio and visual components would impede privacy and that parents may read their child's responses or exert control over the process. Nearly all adolescents stated they would be comfortable with the option to complete the tool at home via a Web portal. Most adolescents stated they would feel comfortable discussing tobacco with their doctor. Adolescent interviews elicited 3 emergent themes that added context to perspectives on confidentiality and had practical implications for implementation: (1) purity: an expressed lack of concern for confidentiality among adolescents with no reported history of tobacco use; (2) steadfast honesty: a commitment to being honest with parents and providers about tobacco use, regardless of the situation; and (3) indifference: a perceived lack of relevance of confidentiality, based on the premise that others will "find out anyway" if adolescents are using tobacco. CONCLUSIONS: This study informed several modifications to the intervention to address confidentiality and introduce efficiency to well-care visits. The support tool was integrated into the electronic health record system used by the study clinics and modified to offer videos to all adolescents regardless of their tobacco use or susceptibility. Future studies will further test the acceptability of the intervention in practice.