Ceramics have some of the highest strength- and stiffness-to-weight ratios of any material but are suboptimal for use as structural materials because of their brittleness and sensitivity to flaws. We ...demonstrate the creation of structural metamaterials composed of nanoscale ceramics that are simultaneously ultralight, strong, and energy-absorbing and can recover their original shape after compressions in excess of 50% strain. Hollow-tube alumina nanolattices were fabricated using two-photon lithography, atomic layer deposition, and oxygen plasma etching. Structures were made with wall thicknesses of 5 to 60 nanometers and densities of 6.3 to 258 kilograms per cubic meter. Compression experiments revealed that optimizing the wall thickness-to-radius ratio of the tubes can suppress brittle fracture in the constituent solid in favor of elastic shell buckling, resulting in ductile-like deformation and recoverability.
Recent studies of human respiratory secretions using culture-independent techniques have found a surprisingly diverse array of microbes. Interactions among these community members can profoundly ...impact microbial survival, persistence and antibiotic susceptibility and, consequently, disease progression. Studies of polymicrobial interactions in the human microbiota have shown that the taxonomic and structural compositions, and resulting behaviours, of microbial communities differ substantially from those of the individual constituent species and in ways of clinical importance. These studies primarily involved oral and gastrointestinal microbiomes. While the field of polymicrobial respiratory disease is relatively young, early findings suggest that respiratory tract microbiota members also compete and cooperate in ways that may influence disease outcomes. Ongoing efforts therefore focus on how these findings can inform more 'enlightened', rational approaches to combat respiratory infections. Among the most common respiratory diseases involving polymicrobial infections are cystic fibrosis (CF), non-CF bronchiectasis, COPD and ventilator-associated pneumonia. While respiratory microbiota can be diverse, two of the most common and best-studied members are
and
, which exhibit a range of competitive and cooperative interactions. Here, we review the state of research on pulmonary coinfection with these pathogens, including their prevalence, combined and independent associations with patient outcomes, and mechanisms of those interactions that could influence lung health. Because
coinfection is common and well studied in CF, this disease serves as the paradigm for our discussions on these two organisms and inform our recommendations for future studies of polymicrobial interactions in pulmonary disease.
Creating lightweight, mechanically robust materials has long been an engineering pursuit. Many siliceous skeleton species--such as diatoms, sea sponges and radiolarians--have remarkably high ...strengths when compared with man-made materials of the same composition, yet are able to remain lightweight and porous. It has been suggested that these properties arise from the hierarchical arrangement of different structural elements at their relevant length scales. Here, we report the fabrication of hollow ceramic scaffolds that mimic the length scales and hierarchy of biological materials. The constituent solids attain tensile strengths of 1.75 GPa without failure even after multiple deformation cycles, as revealed by in situ nanomechanical experiments and finite-element analysis. We discuss the high strength and lack of failure in terms of stress concentrators at surface imperfections and of local stresses within the microstructural landscape. Our findings suggest that the hierarchical design principles offered by hard biological organisms can be applied to create damage-tolerant lightweight engineering materials.
New neurons continue to be generated in the dentate gyrus throughout life, providing this region of the hippocampus with exceptional structural plasticity, but the function of this ongoing ...neurogenesis is unknown. Inhibition of adult neurogenesis produces some behavioral impairments that suggest a role for new neurons in learning and memory; however, other behavioral changes appear inconsistent with this function. A review of studies investigating the function of the hippocampus going back several decades reveals many ideas that seem to converge on a critical role for the hippocampus in stress response and emotion. These potential hippocampal functions provide new avenues for investigating the behavioral functions of adult neurogenesis. And, conversely, studies in animals lacking adult neurogenesis, which are likely to have more limited and more specific impairments than are seen with lesions, may provide valuable new insights into the function of the hippocampus. A complete understanding of the function of the hippocampus must explain its role in emotion and the relationship between its emotional and memory functions.
In 1903, Alexander Graham Bell developed a design principle to generate lightweight, mechanically robust lattice structures based on triangular cells; this has since found broad application in ...lightweight design. Over one hundred years later, the same principle is being used in the fabrication of nanolattice materials, namely lattice structures composed of nanoscale constituents. Taking advantage of the size‐dependent properties typical of nanoparticles, nanowires, and thin films, nanolattices redefine the limits of the accessible material‐property space throughout different disciplines. Herein, the exceptional mechanical performance of nanolattices, including their ultrahigh strength, damage tolerance, and stiffness, are reviewed, and their potential for multifunctional applications beyond mechanics is examined. The efficient integration of architecture and size‐affected properties is key to further develop nanolattices. The introduction of a hierarchical architecture is an effective tool in enhancing mechanical properties, and the eventual goal of nanolattice design may be to replicate the intricate hierarchies and functionalities observed in biological materials. Additive manufacturing and self‐assembly techniques enable lattice design at the nanoscale; the scaling‐up of nanolattice fabrication is currently the major challenge to their widespread use in technological applications.
Nanolattices are highly ordered three‐dimensional architectures composed of nanoscale constituents, and have, in the recent past, redefined the limits of the accessible material‐property space throughout different disciplines. The exceptional mechanical properties of nanolattices, including their ultrahigh strength, damage tolerance, and stiffness, are reviewed, and their potential for multifunctional applications beyond mechanics, relevant fabrication methods, and future directions are discussed.
Background:
Anxiety, depression and fatigue are commonly reported by persons with multiple sclerosis (PwMS).
Objectives:
We estimated the prevalence of each factor in a representative sample of PwMS, ...and in subgroups defined by age, sex and disease duration, at cohort entry and over time. We further examined whether and how these factors clustered together.
Methods:
A population-based longitudinal cohort of 198 PwMS was followed 6-monthly for 2.5 years. The Hospital Anxiety and Depression Scale (HADS) was used to measure anxiety (cut-point >7) and depression (>7) and the Fatigue Severity Scale (FSS) to measure fatigue (≥5).
Results:
At cohort entry, prevalence of anxiety was 44.5% (95%CI 37–51%), depression 18.5% (95%CI 12.6–23.4%), and fatigue 53.7% (95%CI 47–61%). Fatigue was more common in males than females (RR 1.29, p=0.01), with attenuation of the effect after adjustment for Expanded Disability Status Scale (adjusted RR 1.18, p=0.13). Prevalence of anxiety (but not depression or fatigue) decreased by 8.1% per year of cohort observation (RR 0.92, 95%CI 0.86–0.98, p=0.009), with the effect more pronounced in women (14.6%, RR 0.85, 95%CI 0.79–0.93, –<0.001) than men (2.6%, RR 1.03, 95%CI 0.90–1.17, p=0.77). There was no apparent seasonal variation in the prevalence of any of the three factors (p>0.05). All three factors occurred contemporaneously at cohort entry in a higher proportion of the cohort than expected by chance (p<0.001).
Conclusions:
Anxiety, depression and fatigue are common in PwMS and tend to cluster together. The findings are important for clinical management of PwMS and to the exploration of possible shared causal biological pathways.
On-road emissions sources degrade air quality, and these sources have been highly regulated. Epidemiological and environmental justice studies often use road proximity as a proxy for traffic-related ...air pollution (TRAP) exposure, and other studies employ air quality models or satellite observations. To assess these metrics’ abilities to reproduce observed near-road concentration gradients and changes over time, we apply a hierarchical linear regression to ground-based observations, long-term air quality model simulations using Community Multiscale Air Quality (CMAQ), and satellite products. Across 1980–2019, observed TRAP concentrations decreased, and road proximity was positively correlated with TRAP. For all pollutants, concentrations decreased fastest at locations with higher road proximity, resulting in “flatter” concentration fields in recent years. This flattening unfolded at a relatively constant rate for NO x , whereas the flattening of CO concentration fields has slowed. CMAQ largely captures observed spatial–temporal NO2 trends across 2002–2010 but overstates the relationships between CO and elemental carbon fine particulate matter (EC) road proximity. Satellite NO x measures overstate concentration reductions near roads. We show how this perspective provides evidence that California’s on-road vehicle regulations led to substantial decreases in NO2, NO x , and EC in California, with other states that adopted California’s light-duty automobile standards showing mixed benefits over states that did not adopt these standards.
Stem cells mechanosense the stiffness of their microenvironment, which impacts differentiation. Although tissue hydration anti-correlates with stiffness, extracellular matrix (ECM) stiffness is ...clearly transduced into gene expression via adhesion and cytoskeleton proteins that tune fates. Cytoskeletal reorganization of ECM can create heterogeneity and influence fates, with fibrosis being one extreme.
The production of force and power are inherent properties of skeletal muscle, and regulated by contractile proteins within muscle fibers. However, skeletal muscle integrity and function also require ...strong connections between muscle fibers and their extracellular matrix (ECM). A well-organized and pliant ECM is integral to muscle function and the ability for many different cell populations to efficiently migrate through ECM is critical during growth and regeneration. For many neuromuscular diseases, genetic mutations cause disruption of these cytoskeletal-ECM connections, resulting in muscle fragility and chronic injury. Ultimately, these changes shift the balance from myogenic pathways toward fibrogenic pathways, culminating in the loss of muscle fibers and their replacement with fatty-fibrotic matrix. Hence a common pathological hallmark of muscular dystrophy is prominent fibrosis. This review will cover the salient features of muscular dystrophy pathogenesis, highlight the signals and cells that are important for myogenic and fibrogenic actions, and discuss how fibrosis alters the ECM of skeletal muscle, and the consequences of fibrosis in developing therapies.
•Muscular dystrophy pathology creates an imbalance between myogenic and fibrogenic pathways within skeletal muscle.•Signaling mechanisms promoting fibrosis include TGFβ, myostatin, hypoxia, and mechanical stiffness.•Fibrosis compromises coordination amid satellite cells, inflammatory cells, and fibro/adipogenic progenitors in regeneration.•A major consequence of fibrosis is that it is a barrier to efficient cell-based therapies for muscle disease.•Collagen cross-linking and tissue strain limit extracellular matrix degradation to promote fibrotic progression.
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•A simple and affordable protocol to fabricate μPADs was proposed based on the use of a 3D pen.•Hydrophobic barriers were effectively created with an acrylate-based resin.•The ...barriers revealed good chemical resistance when exposed to organic solvents.•The reported protocol allows the creation of zones with 2 mm diameter and channels with 3 mm width.•Clinical and environmental applications were successfully reported.
This paper describes for the first time the use of a 3D pen to fabricate paper-based analytical devices. 3D pens are usually commercialized as “toy for children” and a kit containing four units and a handheld flashlight can be found at cost of US$ 10−15. The protocol involves the 3D pen drawing of the desirable layout on paper using an acrylic resin followed by a curing stage through a handheld flashlight. The barriers created with 3D pen revealed good chemical resistance when exposed to acid and alkaline solutions, surfactants and organic solvents, except ethanol. The proposed approach enabled the creation of zones with 2 mm diameter and channels with 3 mm wide. The analytical feasibility of the devices created with 3D pen was investigated through colorimetric measurements of clinically and environmentally relevant analytes using a free application for image capture and analysis. Considering the instrumental simplicity and the satisfactory analytical performance, we believe the reported approach exhibits potentiality to be implemented in laboratories or research centers with limited resources, opening possibilities to create the desirable devices for the point-of-need applications using only a pen and a flashlight.
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