Cements in the 21st Century: Challenges, Perspectives, and Opportunities.

In a book published in 1906, Richard Meade outlined the history of portland cement up to that point1. Since then there has been great progress in portland cement-based construction materials technologies brought about by advances in the materials science of composites and the development of chemical additives (admixtures) for applications. The resulting functionalities, together with its economy and the sheer abundance of its raw materials, have elevated ordinary portland cement (OPC) concrete to the status of most used synthetic material on Earth. While the 20th century was characterized by the emergence of computer technology, computational science and engineering, and instrumental analysis, the fundamental composition of portland cement has remained surprisingly constant. And, although our understanding of ordinary portland cement (OPC) chemistry has grown tremendously, the intermediate steps in hydration and the nature of calcium silicate hydrate (C-S-H), the major product of OPC hydration, remain clouded in uncertainty. Nonetheless, the century also witnessed great advances in the materials technology of cement despite the uncertain understanding of its most fundamental components. Unfortunately, OPC also has a tremendous consumption-based environmental impact, and concrete made from OPC has a poor strength-to-weight ratio. If these challenges are not addressed, the dominance of OPC could wane over the next 100 years. With this in mind, this paper envisions what the 21st century holds in store for OPC in terms of the driving forces that will shape our continued use of this material. Will a new material replace OPC, and concrete as we know it today, as the preeminent infrastructure construction material?

Multiplex single molecule counting technology used to generate interleukin 4, interleukin 6, and interleukin 10 reference limits.

Detecting biomarkers at pg/ml concentrations or below is, in many situations, critical for quantifying levels in healthy individuals as well as the changes that can occur in the progression of disease states. The ability to detect multiple biomarkers from the same sample allows for better diagnoses, more efficient testing, and lower volumes of sample required. Based on single molecule counting technology, a multiplex instrument was designed and built that is capable of detecting cytokines and other low-abundance proteins at sub-pg/ml quantities in human plasma samples. The multiplex single molecule counting instrument was used to generate 95% reference limits for interleukin 4 (IL-4, <0.61 pg/ml), interleukin 6 (IL-6, <6.53 pg/ml), and interleukin 10 (IL-10, <1.08 pg/ml) from 100 healthy human donor plasma samples, with more than 90% of IL-4 concentrations and 100% of IL-6 and IL-10 concentrations above the limit of detection.

Our House Is on Fire: Child and Adolescent Psychiatrists in the Era of the Climate Crisis.

The global climate crisis has arrived and is impacting pediatric mental health in the form of children facing more frequent and severe weather-related trauma, experiencing climate-related deprivation and displacement, and experiencing anxiety and grief related to inevitable losses to come. Child and adolescent psychiatrists must respond: we are care providers to individuals and families in distress; we are contributors to the crisis through our own emissions; and we are potential mediators of the crisis, somewhat uniquely, as we work to instill agency and hope.

Open-source automated chemical vapor deposition system for the production of two- dimensional nanomaterials.

The study of two- dimensional (2D) materials is a rapidly growing area within nanomaterials research. However, the high equipment costs, which include the processing systems necessary for creating these materials, can be a barrier to entry for some researchers interested in studying these novel materials. Such process systems include those used for chemical vapor deposition, a preferred method for making these materials. To address this challenge, this article presents the first open-source design for an automated chemical vapor deposition system that can be built for less than a third of the cost for a comparable commercial system. The materials and directions for the system are divided by subsystems, which allows the system to be easily built, customized and upgraded, depending upon the needs of the user. We include the details for the specific hardware that will be needed, instructions for completing the build, and the software needed to automate the system. With a chemical vapor deposition system built as described, a variety of 2D nanomaterials and their heterostructures can be grown. Specifically, the experimental results clearly demonstrate the capability of this open-source design in producing high quality, 2D nanomaterials such as graphene and tungsten disulfide, which are at the forefront of research in emerging semiconductor devices, sensors, and energy storage applications.

No Indians to Spare: Depression and Suicide in Indigenous American Children and Youth.

This article summarizes current knowledge and consensus about depression and suicide among the indigenous young people of the United States. American Indians represent more than 500 tribes and also vary among settings-reservations, urban, suburban, and rural-but as a group, remain at high risk for suicide and possibly for depressive syndromes. Particular risk factors and correlates, as well as approaches to treatment, are discussed.

Ultrasensitive quantification of cardiac troponin I by a Single Molecule Counting method: analytical validation and biological features.

AIM: To evaluate analytical and biological characteristics of the Singulex Clarity® cTnI assay, based upon Single Molecule Counting technology. METHODS: Assay's analytical sensitivity, precision, linearity, hook effect, cross-reactivity or interference by endogenous and exogenous substances, stability, 99th reference percentile [p99th] in EDTA plasma were evaluated in single or multi-site studies. RESULTS: Detection limit was 0.12 ng/L. Sensitivity was 0.14 ng/L at 20% CV (functional sensitivity) and 0.53 ng/L at 10% CV. Imprecision was 3.16%-10.0% in a multi-lot, single-site study, and 5.5%-12.0% in a single-lot, multi-site study; assay was linear from 0.08 to 25,000 ng/L. No hook effect was observed; any cross-reactivity/interference exceeded the 10%. Healthy subjects were recruited using clinical history, normal NT-proBNP and eGFR (n = 560) or plasma creatinine (n = 535) as inclusion criteria. cTnI was detectable in 96.8% of healthy subjects. The p99th were 8.01 (eGFR used) and 8.15 ng/L (plasma creatinine); both were measured with ≤5.7% CV. Median cTnI were significantly higher in older and male than in young and female subjects. CONCLUSIONS: The Singulex Clarity cTnI assay show analytical features and % detection in healthy subjects that improve the corresponding values of most of the existing high-sensitivity cTnI assays.

Hydration of tricalcium and dicalcium silicate mixtures studied using quasielastic neutron scattering.

Quasielastic neutron scattering was used to study the hydration reaction of tricalcium and dicalcium silicate mixtures by following the fixation of hydrogen into the reaction products, and by applying hydration models to the data. The reaction kinetics were well-described by an Avrami-derived model for the nucleation and growth regime during early hydration times and a diffusion-limited model for later periods. This study showed that the hydration reaction is not a simple linear combination of the reactions for the individual components. Compressive strength tests correlated with the neutron scattering data, suggesting that the details of the interaction affect the microstructure and therefore the strength of the product. Results suggest that favorable reaction mechanics provide optimal strength when an 80-95% tricalcium silicate and 20-5% dicalcium silicate mixture is used.

Clinical effects of nitrous oxide conscious sedation in children.

PURPOSE: This study examined the clinical effects of nitrous oxide conscious sedation on children. METHODS: Fifty-nine healthy children (ages 4 to 13, mean age=7.7 yrs.) requiring dental restorative treatment with nitrous oxide sedation were studied. The behavior and clinical effects were assessed before and 5 minutes after 50% nitrous oxide sedation. In addition, the children were instructed to draw 4 selected figures from the Bender Visual Motor Gestalt Test to evaluate psychomotor performance and report on their perceived feelings with nitrous oxide. The total sample was divided into various groups for analysis by age, gender, and prior nitrous oxide experience. RESULTS: The most common effects of nitrous oxide sedation were open hands (90%), limp legs (81%), and facial smile (66%). Almost all of the children (95%) liked the nitrous oxide, and 86% reported feeling different. In the measure of psychomotor performance, 75% of the children had 2 or less errors initially and 5 or less errors with nitrous oxide. CONCLUSIONS: There are observable signs and perceived symptoms of nitrous oxide conscious sedation in children. In addition, nitrous oxide at a concentration of 50% has a small but significant effect on the psychomotor ability of children.

Medical risks and benefits of the sweat lodge.

BACKGROUND: The ancient practice of the sweat lodge is increasingly common as part of healing practice in substance abuse and other programs for American Indians. It is popular outside Indian culture as well. Reported deaths of four whites in sweat-type ceremonies, however, suggest a need for medical caution. OBJECTIVES: This review of the available literature summarizes psychologic, spiritual, and medical benefits and risks, using Finnish sauna as the nearest physiologic model for some aspects. CONCLUSIONS: Alcohol use just before, ischemic heart disease, and sweating alone appear to be major risk factors.

Numerical simulation of the PGNA signal from chlorine diffusion gradients in concrete.

A nondestructive test method for detecting chlorides in concrete has been developed based on prompt gamma neutron activation (PGNA). Its performance has been modeled using a hybrid MCNP/optical ray tracing approach. Since the chlorides often come from de-icing salts applied to the concrete surface, the Cl concentration has a non-linear depth profile which is typically modeled by the erfc function. The signals from this distribution have been simulated for several significant Cl capture peaks to estimate the erfc function parameters.

Ultrasensitive flow-based immunoassays using single-molecule counting.

BACKGROUND: Immunoassay (IA) technology has expanded the clinical utility of protein biomarkers, but demands for increased sensitivity, dynamic reporting ranges, and small sample volumes have limited the potential clinical usefulness of many biomarkers. We assessed the performance, including limits of detection (LODs) and the dynamic reporting range, of an IA-based technology, Erenna Immunoassay System, for a series of biomarkers, including cardiac troponin I (cTnI). METHODS: Erenna IAs were used with 10 different and clinically important biomarkers to ascertain the LOD with various sample sizes (10 microL to 200 microL). RESULTS: The Erenna Immunoassay System generated LODs of 10-100 pg/L using 100 microL of sample. For cTnI, the LOD was 0.2 ng/L and a 10% CV was seen between 0.78 and 1.6 ng/L. CONCLUSIONS: The Erenna IA-based technology reproducibly measures protein biomarkers with detection limits of 10-100 pg/L, with a dynamic range of >4.5 logs in sample volumes of 50-150 microL.