The effect of oxygen impurities on the stability and structural properties of vacancy-ordered and -disordered ZrCx

Theoretical calculations predict several long-range ordered sub-stoichiometric zirconium carbide phases to be stable at low temperature, rather than a random (disordered solution) distribution of vacancies. However, experimental synthesis of vacancy-ordered phases is extremely challenging and not all predicted phases have been experimentally observed. It has been hypothesised that the inevitable oxygen contamination in experimental samples may affect the vacancy ordering. In this work, the stability and structural properties of the vacancy-ordered and vacancy-disordered phases are investigated as a function of oxygen defect concentration using first-principles calculations. The observed trends are explained in terms of changes to the local bonding in the presence of varying amounts of oxygen and vacancies. It is found that the relative stability of the ordered phases (compared to the disordered phase at the same composition) decreases as oxygen concentration increases, and some vacancy-ordered phases are destabilised by the level of oxygen impurities found in experimental samples. This suggests that oxygen contamination is a contributing factor to the challenge of synthesising ordered zirconium carbides, and gives insight that may assist fabrication in the future. The volume of all ZrC_x (x ≤ 1) phases was found to decrease with increasing oxygen concentration, which can be attributed to the different ionocovalent nature of the C–Zr and O–Zr bonds. The volume of the vacancy-ordered phases within the expected oxygen solubility limit is greater than the disordered phase of the same composition, which is explained in terms of the relative bond strengths surrounding different vacancy distributions.

First-principles calculations are used to explore vacancy ordering in zirconium carbide at various stoichiometries as affected by oxygen impurities. Atomic bonding and electronic charge distribution are linked to stability and volume trends as a function of O concentration.     

Lupus education for physicians and patients in a resource-limited setting

Clinical Rheumatology - Systemic lupus erythematosus (SLE) is a chronic autoimmune disease with a wide range of manifestations and potential to affect several organ systems. Complications arise...     

Influence of gender,BMI and body shape on theoretical injection outcome at the ventrogluteal and dorsogluteal sites

Aims and objectives

This study aimed to determine the influences of gender, BMI and observed body shape on subcutaneous fat and muscle thicknesses, and theoretical injection outcome, at the ventrogluteal and dorsogluteal intramuscular injection sites.

Background

Debate continues as to whether the dorsogluteal or ventrogluteal injection site is more reliable for a successful intramuscular injection outcome. Subcutaneous fat and muscle thicknesses at the injection site are direct determinants of intramuscular injection outcome. BMI and observed body shape influence gluteal subcutaneous fat and muscle thicknesses, and therefore injection outcome, with potentially distinct effects at the ventrogluteal and dorsogluteal sites.

Design

This was a cross‐sectional study.

Methods

Demographic data were collected, and subcutaneous fat and muscle thicknesses were quantified bilaterally at the dorsogluteal and ventrogluteal injection sites using ultrasound, for 145 participants (57% female).

Results

Subcutaneous fat and muscle were significantly thicker at the dorsogluteal than the ventrogluteal site, and 75% and 86% of participants would receive a successful intramuscular injection at these sites, respectively. There were significant effects of gender, BMI and observed body shape on subcutaneous fat thickness and theoretical injection outcome at both sites. Females, obese individuals and endomorph individuals had thicker subcutaneous fat and were more likely to have a subcutaneous injection outcome.

Conclusions

Gender, BMI and observed body shape could be used to guide site and needle length selection when administering gluteal intramuscular injections to increase the likelihood of a successful intramuscular injection outcome.

Relevance to clinical practice

Both gluteal injection sites should be avoided in obese individuals and endomorph individuals. An intramuscular injection will be successful: using a 32‐mm needle at the ventrogluteal site for all males and normal‐weight females and using a 38‐mm needle for all females at the ventrogluteal site, and for all males and at least 98% of females at the dorsogluteal site.     

Three differentiation states risk-stratify bladder cancer into distinct subtypes

Current clinical judgment in bladder cancer (BC) relies primarily on pathological stage and grade. We investigated whether a molecular classification of tumor cell differentiation, based on a developmental biology approach, can provide additional prognostic information. Exploiting large preexisting gene-expression databases, we developed a biologically supervised computational model to predict markers that correspond with BC differentiation. To provide mechanistic insight, we assessed relative tumorigenicity and differentiation potential via xenotransplantation. We then correlated the prognostic utility of the identified markers to outcomes within gene expression and formalin-fixed paraffin-embedded (FFPE) tissue datasets. Our data indicate that BC can be subclassified into three subtypes, on the basis of their differentiation states: basal, intermediate, and differentiated, where only the most primitive tumor cell subpopulation within each subtype is capable of generating xenograft tumors and recapitulating downstream populations. We found that keratin 14 (KRT14) marks the most primitive differentiation state that precedes KRT5 and KRT20 expression. Furthermore, KRT14 expression is consistently associated with worse prognosis in both univariate and multivariate analyses. We identify here three distinct BC subtypes on the basis of their differentiation states, each harboring a unique tumor-initiating population.     

Identifying inadequate response among patients with ankylosing spondylitis and psoriatic arthritis prescribed advanced therapy in a real-world,commercially insured adult population in the USA

Clinical Rheumatology - This study aimed to assess treatment patterns and frequency of inadequate response associated with advanced therapy initiation among patients with ankylosing spondylitis...