International Interlaboratory Comparison of Thermogravimetric Analysis of Graphene-Related Two-Dimensional Materials.

Research on graphene-related two-dimensional (2D) materials (GR2Ms) in recent years is strongly moving from academia to industrial sectors with many new developed products and devices on the market. Characterization and quality control of the GR2Ms and their properties are critical for growing industrial translation, which requires the development of appropriate and reliable analytical methods. These challenges are recognized by International Organization for Standardization (ISO 229) and International Electrotechnical Commission (IEC 113) committees to facilitate the development of these methods and standards which are currently in progress.

Thickness measurements of graphene oxide flakes using atomic force microscopy: results of an international interlaboratory comparison.

Flake thickness is one of the defining properties of graphene-related 2D materials (GR2Ms), and therefore requires reliable, accurate, and reproducible measurements with well-understood uncertainties. This is needed regardless of the production method or manufacturer because it is important for all GR2M products to be globally comparable. An international interlaboratory comparison on thickness measurements of graphene oxide flakes using atomic force microscopy has been completed in technical working area 41 of versailles project on advanced materials and standards.

Development challenges in challenging contexts: A 3-stage curriculum framework design approach for Education in Emergencies.

There is a pressing need to develop processes to facilitate the organization of education responses in time-pressured emergency situations. As part of a joint Learning Passport (LP) partnership project with UNICEF, researchers along with curriculum and subject specialists at the University of Cambridge, UK, developed a curriculum framework that could be used as a resource for coordinating the actions of education specialists and practitioners in Education in Emergencies (EiE) situations. This article outlines the curriculum framework design approach they developed for the Maths and Science components of the LP framework.

Compartment specific regulation of sleep by mushroom body requires GABA and dopaminergic signaling.

Sleep is a fundamental behavioral state important for survival and is universal in animals with sufficiently complex nervous systems. As a highly conserved neurobehavioral state, sleep has been described in species ranging from jellyfish to humans. Biogenic amines like dopamine, serotonin and norepinephrine have been shown to be critical for sleep regulation across species but the precise circuit mechanisms underlying how amines control persistence of sleep, arousal and wakefulness remain unclear.

New Multiscale Characterization Methodology for Effective Determination of Isolation-Structure-Function Relationship of Extracellular Vesicles.

Extracellular vesicles (EVs) have been lauded as next-generation medicines, but very few EV-based therapeutics have progressed to clinical use. Limited clinical translation is largely due to technical barriers that hamper our ability to mass produce EVs, i.e.

Does gas supersaturation by a chemical reaction produce bulk nanobubbles?

Hypothesis: Supersaturation of dissolved gas is the most commonly reported method for generating long-lived bulk nanobubbles. However, these reports are treated with skepticism because of the lack of techniques that directly show that these particles are gas filled bubbles. Therefore, this work has tested the hypothesis that supersaturation obtained by a chemical reaction produces long-lived nanosized bubbles in bulk using an established protocol that relies on evaluating the density of nanoparticles and measuring their response to external pressure.

Size and shape distributions of primary crystallites in titania aggregates.

The primary crystallite size of titania powder relates to its properties in a number of applications. Transmission electron microscopy was used in this interlaboratory comparison (ILC) to measure primary crystallite size and shape distributions for a commercial aggregated titania powder. Data of four size descriptors and two shape descriptors were evaluated across nine laboratories.

Quantification of nanoparticle concentration in colloidal suspensions by a non-destructive optical method.

The estimation of nanoparticle number concentration in colloidal suspensions is a prerequisite in many procedures, and in particular in multi-stage, low-yield reactions. Here, we describe a rapid, non-destructive method based on optical extinction and dynamic light scattering (DLS), which combines measurements using common bench-top instrumentation with a numerical algorithm to calculate the particle size distribution (PSD) and concentration. These quantities were derived from Mie theory applied to measurements of the optical extinction spectrum of homogeneous, non-absorbing nanoparticles, and the relative PSD of a colloidal suspension.

Improved Metrological Traceability of Particle Size Values Measured with Line-Start Incremental Centrifugal Liquid Sedimentation.

Line-start incremental centrifugal liquid sedimentation (disc-CLS) is a powerful method to determine particle size based on the principles of Stokes' law. Because several of the input quantities of the Stokes equation cannot be easily determined for this case of a rotating disc, the disc-CLS approach relies on calibrating the sedimentation time scale with reference particles. To use these calibrant particles for establishing metrological traceability, they must fulfill the same requirements as those imposed on a certified reference material, i.

Challenges in the size analysis of a silica nanoparticle mixture as candidate certified reference material.

A new certified reference material for quality control of nanoparticle size analysis methods has been developed and produced by the Institute for Reference Materials and Measurements of the European Commission's Joint Research Centre. The material, ERM-FD102, consists of an aqueous suspension of a mixture of silica nanoparticle populations of distinct particle size and origin. The characterisation relied on an interlaboratory comparison study in which 30 laboratories of demonstrated competence participated with a variety of techniques for particle size analysis.

A comparative study of submicron particle sizing platforms: accuracy, precision and resolution analysis of polydisperse particle size distributions.

The particle size distribution (PSD) of a polydisperse or multimodal system can often be difficult to obtain due to the inherent limitations in established measurement techniques. For this reason, the resolution, accuracy and precision of three new and one established, commercially available and fundamentally different particle size analysis platforms were compared by measuring both individual and a mixed sample of monodisperse, sub-micron (220, 330, and 410 nm - nominal modal size) polystyrene particles. The platforms compared were the qNano Tunable Resistive Pulse Sensor, Nanosight LM10 Particle Tracking Analysis System, the CPS Instruments's UHR24000 Disc Centrifuge, and the routinely used Malvern Zetasizer Nano ZS Dynamic Light Scattering system.

Single particle inductively coupled plasma-mass spectrometry: a performance evaluation and method comparison in the determination of nanoparticle size.

Sizing engineered nanoparticles in simple, laboratory systems is now a robust field of science; however, application of available techniques to more complex, natural systems is hindered by numerous challenges including low nanoparticle number concentrations, polydispersity from aggregation and/or dissolution, and interference from other incidental particulates. A new emerging technique, single particle inductively coupled plasma-mass spectrometry (spICPMS), has the potential to address many of these analytical challenges when sizing inorganic nanoparticles in environmental matrices. However, to date, there is little beyond the initial feasibility studies that investigates the performance characteristics and validation of spICPMS as a nanoparticle sizing technique.

Tissue distribution of inhaled micro- and nano-sized cerium oxide particles in rats: results from a 28-day exposure study.

In order to obtain more insight into the tissue distribution, accumulation, and elimination of cerium oxide nanoparticles after inhalation exposure, blood and tissue kinetics were investigated during and after a 28-day inhalation study in rats with micro- and nanocerium oxide particles (nominal primary particle size: < 5000, 40, and 5-10 nm). Powder aerosolization resulted in comparable mass median aerodynamic diameter (1.40, 1.

Evaluation of a droplet digital polymerase chain reaction format for DNA copy number quantification.

Droplet digital polymerase chain reaction (ddPCR) is a new technology that was recently commercialized to enable the precise quantification of target nucleic acids in a sample. ddPCR measures absolute quantities by counting nucleic acid molecules encapsulated in discrete, volumetrically defined, water-in-oil droplet partitions. This novel ddPCR format offers a simple workflow capable of generating highly stable partitioning of DNA molecules.

Determining transport efficiency for the purpose of counting and sizing nanoparticles via single particle inductively coupled plasma mass spectrometry.

Currently there are few ideal methods for the characterization of nanoparticles in complex, environmental samples, leading to significant gaps in toxicity and exposure assessments of nanomaterials. Single particle-inductively coupled plasma-mass spectrometry (spICPMS) is an emerging technique that can both size and count metal-containing nanoparticles. A major benefit of the spICPMS method is its ability to characterize nanoparticles at concentrations relevant to the environment.

Glucocorticoid inhibition in the treatment of depression: can we think outside the endocrine hypothalamus?

Background: Major depressive disorder affects a substantial percentage of the U.S. population, and can be highly debilitating.

United States obstetrician-gynecologists' accuracy in the simulation of diagnosing anxiety disorders and depression during pregnancy.

The objective of this study was to examine obstetrician-gynecologists' diagnostic accuracy for mental health issues during pregnancy through utilization of clinical vignettes describing depressive and anxiety symptoms, as well as to explore factors associated with increased diagnostic accuracy and related practice patterns. Questionnaires were mailed to 1193 American College of Obstetricians and Gynecologists Fellows and Junior Fellows. The response rate was 44% after three mailings.

Obstetrician-gynecologists and primary care: training during obstetrics-gynecology residency and current practice patterns.

Purpose: To assess obstetrician-gynecologists' perceptions of their residency training in primary care, document health issues assessed at annual visits, and identify practice patterns of both generalist and specialist obstetrician-gynecologists.

Method: Questionnaires were mailed to a random sample of 1,711 American College of Obstetricians and Gynecologists Young Fellows in September 2005. Information was gathered on perceptions about adequacy of residency training, how well training prepared obstetrician-gynecologists for current practice, and typical practice patterns for various medical diagnoses.

Obstetrician-gynecologists' screening patterns for anxiety during pregnancy.

As obstetrician-gynecologists (ob-gyns) take on a greater role in women's healthcare, it is important that they are aware of the high prevalence of anxiety disorders in their patient population. Anxiety disorders present during pregnancy can have detrimental effects on both mother and child. In this study, we queried 1,193 ob-gyns on their screening rates, practice patterns, training, and knowledge as they relate to anxiety disorders during pregnancy.

Cesarean delivery on maternal request: obstetrician-gynecologists' knowledge, perception, and practice patterns.

Objective: To examine obstetrician-gynecologists' knowledge, opinions, and practice patterns related to cesarean delivery on maternal request.

Methods: Questionnaires were mailed to 1,031 American College of Obstetricians and Gynecologists Fellows in February 2006, with a response rate of 68%. The questionnaire queried respondents' demographic characteristics, practices and attitudes surrounding vaginal and cesarean deliveries, knowledge and beliefs regarding the risks and benefits of elective and nonelective cesarean delivery, and counseling practices and department policies for cesarean delivery on maternal request.