High-throughput quantification of quasistatic, dynamic and spall strength of materials across 10 orders of strain rates.

The response of metals and their microstructures under extreme dynamic conditions can be markedly different from that under quasistatic conditions. Traditionally, high strain rates and shock stresses are achieved using cumbersome and expensive methods such as the Kolsky bar or large spall experiments. These methods are low throughput and do not facilitate high-fidelity microstructure-property linkages. In this work, we combine two powerful small-scale testing methods, custom nanoindentation, and laser-driven microflyer (LDMF) shock, to measure the dynamic and spall strength of metals. The nanoindentation system is configured to test samples from quasistatic to dynamic strain-rate regimes. The LDMF shock system can test samples through impact loading, triggering spall failure. The model material used for testing is magnesium alloys, which are lightweight, possess high-specific strengths, and have historically been challenging to design and strengthen due to their mechanical anisotropy. We adopt two distinct microstructures, solutionized (no precipitates) and peak-aged (with precipitates) to demonstrate interesting upticks in strain-rate sensitivity and evolution of dynamic strength. At high shock-loading rates, we unravel an interesting paradigm where the spall strength vs. strain rate of these materials converges, but the failure mechanisms are markedly different. Peak aging, considered to be a standard method to strengthen metallic alloys, causes catastrophic failure, faring much worse than solutionized alloys. Our high-throughput testing framework not only quantifies strength but also teases out unexplored failure mechanisms at extreme strain rates, providing valuable insights for the rapid design and improvement of materials for extreme environments.

Reproducible graphene synthesis by oxygen-free chemical vapour deposition.

Chemical vapour deposition (CVD) synthesis of graphene on copper has been broadly adopted since the first demonstration of this process1. However, widespread use of CVD-grown graphene for basic science and applications has been hindered by challenges with reproducibility2 and quality3. Here we identify trace oxygen as a key factor determining the growth trajectory and quality for graphene grown by low-pressure CVD. Oxygen-free chemical vapour deposition (OF-CVD) synthesis is fast and highly reproducible, with kinetics that can be described by a compact model, whereas adding trace oxygen leads to suppressed nucleation and slower/incomplete growth. Oxygen affects graphene quality as assessed by surface contamination, emergence of the Raman D peak and decrease in electrical conductivity. Epitaxial graphene grown in oxygen-free conditions is contamination-free and shows no detectable D peak. After dry transfer and boron nitride encapsulation, it shows room-temperature electrical-transport behaviour close to that of exfoliated graphene. A graphite-gated device shows well-developed integer and fractional quantum Hall effects. By highlighting the importance of eliminating trace oxygen, this work provides guidance for future CVD system design and operation. The increased reproducibility and quality afforded by OF-CVD synthesis will broadly influence basic research and applications of graphene.

Performance measurement part I: Foundational knowledge for measure development.

As medicine is moving toward performance and outcome-based payment and is transitioning away from productivity-based systems, value is now being appraised in healthcare through "performance measures." Over the past few decades, assessment of clinical performance in health care has been essential in ensuring safe and cost-effective patient care. The Centers for Medicare & Medicaid Services is further driving this change with measurable, outcomes-based national payer incentive payment systems. With the continually evolving requirements in health care reform focused on value-based care, there is a growing concern that clinicians, particularly dermatologists, may not understand the scientific rationale of health care quality measurement. As such, in order to help dermatologists understand the health care measurement science landscape to empower them to engage in the performance measure development and implementation process, the first article in this 2-part continuing medical education series reviews the value equation, historic and evolving policy issues, and the American Academy of Dermatology's approach to performance measurement development to provide the required foundational knowledge for performance measure developers.

Performance measurement part II: A guide to developing dermatology performance measures.

Throughout the 21st century, national and local governments, private health sectors, health insurance companies, healthcare professionals, labor unions, and consumers have been striving to develop an effective approach to evaluate, report, and improve the quality of healthcare. As medicine improves and health systems grow to meet patient needs, the performance measurement system of care effectiveness must also evolve. Continual efforts should be undertaken to effectively measure quality of care to create a more informed public, improve health outcomes, and reduce healthcare costs. As such, recent policy reform has necessitated that performance systems be implemented in healthcare, with the "performance measure" being the foundation of the system in which all of healthcare must be actively engaged in to ensure optimal care for patients. The development of performance measures can be highly complex, particularly when creating specialty-specific performance measures. To help dermatologists understand the process of creating dermatology-specific performance measures to engage in creating or implementing performance measures at the local or national levels, this article in the two-part continuing medical education series reviews the types, components, and process of developing, reviewing, and implementing performance measures.

"Kissing" basaloid follicular hamartomas of the eyelid.

Basaloid follicular hamartomas (BFHs) are rare, benign, cutaneous adnexal tumors characterized by branching cords and anastomosing strands of basaloid cells in a loose, fibrous stroma. BFHs exhibit variable clinical presentations although they are commonly observed as skin-colored papules and are diagnosed based on histopathological features. Common systemic diseases associated with BFH include alopecia, myasthenia gravis, and palmoplantar pitting. BFH of the eyelid is extremely rare with only five cases reported in the literature to date. Congenital "kissing" lesions have only previously been reported with nevi. Here, we present a novel case of congenital "kissing" BFH of the right upper and right lower eyelid, and histopathological examination revealed intradermal nodules of basaloid cells forming reticulated strands, pseudohorn cysts, mucinous stroma, and palisading with CD34 and Bcl-2 expression in the stromal fibroblasts and periphery, respectively.

Secondary Syphilis With Elastophagocytosis: An Unusual Histologic Finding.

ABSTRACT: Elastophagocytosis is a characteristic finding of granulomatous and elastolytic disorders. It is defined by phagocytosed elastic fibers within histiocytes, multinucleated giant cells, or both. This finding has also been associated with certain medications, malignancies, inflammatory conditions, and infectious disorders. Although Drs Ragaz and Ackerman reported elastophagocytosis in a secondary syphilis lesion in a review of actinic granuloma in 1979, more recent publications have not recognized this finding. We present a case of elastophagocytosis within a lesion of secondary syphilis in a 65-year-old man. Biopsy from his left forearm demonstrated features of secondary syphilis including subtle vacuolar alteration with mild superficial and mid perivascular lymphoplasmacytic inflammation. There were interstitial giant cells with phagocytosed elastic fibers within the superficial dermis. Spirochete immunostain was positive with confirmatory Treponema pallidum IgG antibody and RPR titer. In this report, we present a unique case of secondary syphilis.

Optical conductivity-based ultrasensitive mid-infrared biosensing on a hybrid metasurface.

Optical devices are highly attractive for biosensing as they can not only enable quantitative measurements of analytes but also provide information on molecular structures. Unfortunately, typical refractive index-based optical sensors do not have sufficient sensitivity to probe the binding of low-molecular-weight analytes. Non-optical devices such as field-effect transistors can be more sensitive but do not offer some of the significant features of optical devices, particularly molecular fingerprinting. We present optical conductivity-based mid-infrared (mid-IR) biosensors that allow for sensitive and quantitative measurements of low-molecular-weight analytes as well as the enhancement of spectral fingerprints. The sensors employ a hybrid metasurface consisting of monolayer graphene and metallic nano-antennas and combine individual advantages of plasmonic, electronic and spectroscopic approaches. First, the hybrid metasurface sensors can optically detect target molecule-induced carrier doping to graphene, allowing highly sensitive detection of low-molecular-weight analytes despite their small sizes. Second, the resonance shifts caused by changes in graphene optical conductivity is a well-defined function of graphene carrier density, thereby allowing for quantification of the binding of molecules. Third, the sensor performance is highly stable and consistent thanks to its insensitivity to graphene carrier mobility degradation. Finally, the sensors can also act as substrates for surface-enhanced infrared spectroscopy. We demonstrated the measurement of monolayers of sub-nanometer-sized molecules or particles and affinity binding-based quantitative detection of glucose down to 200 pM (36 pg/mL). We also demonstrated enhanced fingerprinting of minute quantities of glucose and polymer molecules.

Real-Time Monitoring of Insulin Using a Graphene Field-Effect Transistor Aptameric Nanosensor.

This paper presents an approach to the real-time, label-free, specific, and sensitive monitoring of insulin using a graphene aptameric nanosensor. The nanosensor is configured as a field-effect transistor, whose graphene-based conducting channel is functionalized with a guanine-rich IGA3 aptamer. The negatively charged aptamer folds into a compact and stable antiparallel or parallel G-quadruplex conformation upon binding with insulin, resulting in a change in the carrier density, and hence the electrical conductance, of the graphene. The change in the electrical conductance is then measured to enable the real-time monitoring of insulin levels. Testing has shown that the nanosensor offers an estimated limit of detection down to 35 pM and is functional in Krebs-Ringer bicarbonate buffer, a standard pancreatic islet perfusion medium. These results demonstrate the potential utility of this approach in label-free monitoring of insulin and in timely prediction of accurate insulin dosage in clinical diagnostics.

Pemphigus: Pathogenesis to Treatment.

Pemphigus vulgaris (PV), pemphigus foliaceus (PF), and paraneoplastic pemphigus (PNP) are a group of rare and fatal blistering diseases involving autoantibodies that target desmosomal proteins. The pathogenesis of pemphigus involves the production of activated B-cells and IgG with stimulation by IL-4 by T-helper 2 cells. Clinically these diseases present most often with epidermal erosions of the mucosae and skin caused by rapid rupturing of flaccid bullae. These lesions correlate histologically with splits forming in the epidermis, leaving a blister roof composed of a few cell layers. Standard treatment of pemphigus involves oral corticosteroids, often with the addition of adjuvant therapies, to improve disease control, minimize corticosteroids side-effects, and increase the odds of remission. [Full article available at http://rimed.org/rimedicaljournal-2016-12.asp].