Micro-/Nanostructured Mechanical Metamaterials Lee, Jae-Hwang; Singer, Jonathan P.; Thomas, Edwin L.
Advanced materials (Weinheim),
September 18, 2012, Letnik:
24, Številka:
36
Journal Article
Recenzirano
Mechanical properties of materials have long been one of the most fundamental and studied areas of materials science for a myriad of applications. Recently, mechanical metamaterials have been shown ...to possess extraordinary effective properties, such as negative dynamic modulus and/or density, phononic bandgaps, superior thermoelectric properties, and high specific energy absorption. To obtain such materials on appropriate length scales to enable novel mechanical devices, it is often necessary to effectively design and fabricate micro‐/nano‐ structured materials. In this Review, various aspects of the micro‐/nano‐structured materials as mechanical metamaterials, potential tools for their multidimensional fabrication, and selected methods for their structural and performance characterization are described, as well as some prospects for the future developments in this exciting and emerging field.
We review mechanical metamaterials made from micro‐/nano‐structured materials that possess extraordinary effective properties, such as negative dynamic modulus, phononic bandgaps, high specific energy absorption, and unusual heat transport. Potential fabrication tools and selected characterization methods are described as well as some prospects for the future developments in this exciting and emerging field.
The engineering of optical and acoustic material functionalities via construction of ordered local and global architectures on various length scales commensurate with and well below the ...characteristic length scales of photons and phonons in the material is an indispensable and powerful means to develop novel materials. In the current mature status of photonics, polymers hold a pivotal role in various application areas such as light‐emission, sensing, energy, and displays, with exclusive advantages despite their relatively low dielectric constants. Moreover, in the nascent field of phononics, polymers are expected to be a superior material platform due to the ability for readily fabricated complex polymer structures possessing a wide range of mechanical behaviors, complete phononic bandgaps, and resonant architectures. In this review, polymer‐centric photonic and phononic crystals and metamaterials are highlighted, and basic concepts, fabrication techniques, selected functional polymers, applications, and emerging ideas are introduced.
Polymer‐centric photonic and phononic crystals are reviewed focusing on basic concepts, design and fabrication techniques, functional polymers, applications, and emerging ideas. Polymer‐based photonic crystals will become more critical in sensing, energy, and display applications while polymer‐based phononic crystals are expected to be a superior materials platform for manipulating elastic waves over many length scales due to the wide range of applications and relative ease of opening complete bandgaps.
Frailty in Pulmonary and Critical Care Medicine Singer, Jonathan P; Lederer, David J; Baldwin, Matthew R
Annals of the American Thoracic Society,
08/2016, Letnik:
13, Številka:
8
Journal Article
Recenzirano
Odprti dostop
Conceptualized first in the field of geriatrics, frailty is a syndrome characterized by a generalized vulnerability to stressors resulting from an accumulation of physiologic deficits across multiple ...interrelated systems. This accumulation of deficits results in poorer functional status and disability. Frailty is a "state of risk" for subsequent disproportionate declines in health status following new exposure to a physiologic stressor. Two predominant models have emerged to operationalize the measurement of frailty. The phenotype model defines frailty as a distinct clinical syndrome that includes conceptual domains such as strength, activity, wasting, and mobility. The cumulative deficit model defines frailty by enumerating the number of age-related things wrong with a person. The biological pathways driving frailty include chronic systemic inflammation, sarcopenia, and neuroendocrine dysregulation, among others. In adults with chronic lung disease, frailty is independently associated with more frequent exacerbations of lung disease, all-cause hospitalization, declines in functional status, and all-cause mortality. In addition, frail adults who become critically ill are more likely develop chronic critical illness or severe disability and have higher in-hospital and long-term mortality rates. The evaluation of frailty appears to provide important prognostic information above and beyond routinely collected measures in adults with chronic lung disease and the critically ill. The study of frailty in these populations, however, requires multipronged efforts aimed at refining clinical assessments, understanding the mechanisms, and developing therapeutic interventions.
Frailty is associated with increased mortality among lung transplant candidates. We sought to determine the association between frailty, as measured by the Short Physical Performance Battery (SPPB), ...and mortality after lung transplantation. In a multicenter prospective cohort study of adults who underwent lung transplantation, preoperative frailty was assessed with the SPPB (n = 318) and, in a secondary analysis, the Fried Frailty Phenotype (FFP; n = 299). We tested the association between preoperative frailty and mortality following lung transplantation with propensity score–adjusted Cox models. We calculated postestimation marginalized standardized risks for 1‐year mortality by frailty status using multivariate logistic regression. SPPB frailty was associated with an increased risk of both 1‐ and 4‐year mortality (adjusted hazard ratio aHR: 7.5; 95% confidence interval CI: 1.6‐36.0 and aHR 3.8; 95%CI: 1.8‐8.0, respectively). Each 1‐point worsening in SPPB was associated with a 20% increased risk of death (aHR: 1.20; 95%CI: 1.08‐1.33). Frail subjects had an absolute increased risk of death within the first year after transplantation of 12.2% (95%CI: 3.1%‐21%). In secondary analyses, FFP frailty was associated with increased risk of death within the first postoperative year (aHR: 3.8; 95%CI: 1.1‐13.2) but not over longer follow‐up. Preoperative frailty is associated with an increased risk of death after lung transplantation.
In this multicenter prospective cohort study, preoperative physical frailty is independently associated with a substantially higher risk of mortality after lung transplantation.
Although non-vitamin K antagonist oral anticoagulants (NOACs) do not require frequent laboratory monitoring, each compound requires dose adjustments on the basis of certain clinical criteria.
This ...study assessed the frequency of off-label NOAC doses among AF patients and the associations between off-label dose therapy and clinical outcomes in community practice.
We evaluated 5,738 patients treated with a NOAC at 242 ORBIT-AF II (Outcomes Registry for Better Informed Treatment of Atrial Fibrillation phase II) sites. NOAC doses were classified as either underdosed or overdosed, consistent with Food and Drug Administration labeling. Longitudinal outcomes (median follow-up: 0.99 years) included stroke or systemic embolism, myocardial infarction, major bleeding (International Society of Thrombosis and Haemostasis criteria), cause-specific hospitalization, and all-cause mortality.
Overall, 541 NOAC-treated patients (9.4%) were underdosed, 197 were overdosed (3.4%), and 5,000 were dosed according to U.S. labeling (87%). Compared with patients receiving the recommended dose, those who were receiving off-label doses were older (median: 79 and 80 years of age vs. 70 years of age, respectively; p < 0.0001), more likely female (48% and 67% vs. 40%, respectively; p < 0.0001), less likely to be treated by an electrophysiologist (18% and 19% vs. 27%, respectively; p < 0.0001), and had higher CHA
DS
-VASc scores (96% and 97% ≥2 vs. 86%, respectively; p < 0.0001) and higher ORBIT bleeding scores (25% and 31% >4 vs. 11%, respectively; p < 0.0001). After dose adjustment, NOAC overdosing was associated with increased all-cause mortality compared with recommended doses (adjusted hazard ratio: 1.91; 95% confidence interval CI: 1.02 to 3.60; p = 0.04). Underdosing was associated with increased cardiovascular hospitalization (adjusted hazard ratio: 1.26; 95% CI: 1.07 to 1.50; p = 0.007).
A significant minority (almost 1 in 8) of U.S. patients in the community received NOAC doses inconsistent with labeling. NOAC over- and underdosing are associated with increased risk for adverse events. (Outcomes Registry for Better Informed Treatment of Atrial Fibrillation II ORBIT-AF II; NCT01701817).
Objectives This study sought to investigate the outcomes following cardioversion or catheter ablation in patients with atrial fibrillation (AF) treated with warfarin or rivaroxaban. Background There ...are limited data on outcomes following cardioversion or catheter ablation in AF patients treated with factor Xa inhibitors. Methods We compared the incidence of electrical cardioversion (ECV), pharmacologic cardioversion (PCV), or AF ablation and subsequent outcomes in patients in a post hoc analysis of the ROCKET AF (Efficacy and Safety Study of Rivaroxaban With Warfarin for the Prevention of Stroke and Non-Central Nervous System Systemic Embolism in Patients With Non-Valvular Atrial Fibrillation) trial. Results Over a median follow-up of 2.1 years, 143 patients underwent ECV, 142 underwent PCV, and 79 underwent catheter ablation. The overall incidence of ECV, PCV, or AF ablation was 1.45 per 100 patient-years (n = 321; 1.44 n = 161 in the warfarin arm, 1.46 n = 160 in the rivaroxaban arm). The crude rates of stroke and death increased in the first 30 days after cardioversion or ablation. After adjustment for baseline differences, the long-term incidence of stroke or systemic embolism (hazard ratio HR: 1.38; 95% confidence interval CI: 0.61 to 3.11), cardiovascular death (HR: 1.57; 95% CI: 0.69 to 3.55), and death from all causes (HR: 1.75; 95% CI: 0.90 to 3.42) were not different before and after cardioversion or AF ablation. Hospitalization increased after cardioversion or AF ablation (HR: 2.01; 95% CI: 1.51 to 2.68), but there was no evidence of a differential effect by randomized treatment (p value for interaction = 0.58). The incidence of stroke or systemic embolism (1.88% vs. 1.86%) and death (1.88% vs. 3.73%) were similar in the rivaroxaban-treated and warfarin-treated groups. Conclusions Despite an increase in hospitalization, there were no differences in long-term stroke rates or survival following cardioversion or AF ablation. Outcomes were similar in patients treated with rivaroxaban or warfarin. (An Efficacy and Safety Study of Rivaroxaban With Warfarin for the Prevention of Stroke and Non-Central Nervous System Systemic Embolism in Patients With Non-Valvular Atrial Fibrillation ROCKET AF; NCT00403767 )
Background: There is broad consensus regarding the health impact of tobacco use and secondhand smoke exposure, yet considerable ambiguity exists about the nature and consequences of thirdhand smoke ...(THS). Objectives: We introduce definitions of THS and THS exposure and review recent findings about constituents, indoor sorption—desorption dynamics, and transformations of THS; distribution and persistence of THS in residential settings; implications for pathways of exposure; potential clinical significance and health effects; and behavioral and policy issues that affect and are affected by THS. Discussion: Physical and chemical transformations of tobacco smoke pollutants take place over time scales ranging from seconds to months and include the creation of secondary pollutants that in some cases are more toxic (e.g., tobacco-specific nitrosamines). THS persists in real-world residential settings in the air, dust, and surfaces and is associated with elevated levels of nicotine on hands and cotinine in urine of nonsmokers residing in homes previously occupied by smokers. Much still needs to be learned about the chemistry, exposure, toxicology, health risks, and policy implications of THS. Conclusion: The existing evidence on THS provides strong support for pursuing a programmatic research agenda to close gaps in our current understanding of the chemistry, exposure, toxicology, and health effects of THS, as well as its behavioral, economic, and sociocultural considerations and consequences. Such a research agenda is necessary to illuminate the role of THS in existing and future tobacco control efforts to decrease smoking initiation and smoking levels, to increase cessation attempts and sustained cessation, and to reduce the cumulative effects of tobacco use on morbidity and mortality.
Summary Background Digoxin is a widely used drug for ventricular rate control in patients with atrial fibrillation (AF), despite a scarcity of randomised trial data. We studied the use and outcomes ...of digoxin in patients in the Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared with Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET AF). Methods For this retrospective analysis, we included and classified patients from ROCKET AF on the basis of digoxin use at baseline and during the study. Patients in ROCKET AF were recruited from 45 countries and had AF and risk factors putting them at moderate-to-high risk of stroke, with or without heart failure. We used Cox proportional hazards regression models adjusted for baseline characteristics and drugs to investigate the association of digoxin with all-cause mortality, vascular death, and sudden death. ROCKET AF was registered with ClinicalTrials.gov , number NCT00403767. Findings In 14 171 randomly assigned patients, digoxin was used at baseline in 5239 (37%). Patients given digoxin were more likely to be female (42% vs 38%) and have a history of heart failure (73% vs 56%), diabetes (43% vs 38%), and persistent AF (88% vs 77%; p<0·0001 for each comparison). After adjustment, digoxin was associated with increased all-cause mortality (5·41 vs 4·30 events per 100 patients-years; hazard ratio 1·17; 95% CI 1·04–1·32; p=0·0093), vascular death (3·55 vs 2·69 per 100 patient-years; 1·19; 1·03–1·39, p=0·0201), and sudden death (1·68 vs 1·12 events per 100 patient-years; 1·36; 1·08–1·70, p=0·0076). Interpretation Digoxin treatment was associated with a significant increase in all-cause mortality, vascular death, and sudden death in patients with AF. This association was independent of other measured prognostic factors, and although residual confounding could account for these results, these data show the possibility of digoxin having these effects. A randomised trial of digoxin in treatment of AF patients with and without heart failure is needed. Funding Janssen Research & Development and Bayer HealthCare AG.
The COVID-19 pandemic has caused acute lung injury in millions of individuals worldwide. Some patients develop COVID-related acute respiratory distress syndrome (CARDS) and cannot be liberated from ...mechanical ventilation. Others may develop post-COVID fibrosis, resulting in substantial disability and need for long-term supplemental oxygen. In both of these situations, treatment teams often inquire about the possibility of lung transplantation. In fact, lung transplantation has been successfully employed for both CARDS and post-COVID fibrosis in a limited number of patients worldwide. Lung transplantation after COVID infection presents a number of unique challenges that transplant programs must consider. In those with severe CARDS, the inability to conduct proper psychosocial evaluation and pretransplantation education, marked deconditioning from critical illness, and infectious concerns regarding viral reactivation are major hurdles. In those with post-COVID fibrosis, our limited knowledge about the natural history of recovery after COVID-19 infection is problematic. Increased knowledge of the likelihood and degree of recovery after COVID-19 acute lung injury is essential for appropriate decision-making with regard to transplantation. Transplant physicians must weigh the risks and benefits of lung transplantation differently in a post-COVID fibrosis patient who is likely to remain stable or gradually improve in comparison with a patient with a known progressive fibrosing interstitial lung disease (fILD). Clearly lung transplantation can be a life-saving therapeutic option for some patients with severe lung injury from COVID-19 infection. In this review, we discuss how lung transplant providers from a number of experienced centers approach lung transplantation for CARDS or post-COVID fibrosis.
Background The prevalence of both atrial fibrillation (AF) and diabetes mellitus (DM) are rising, and these conditions often occur together. Also, DM is an independent risk factor for stroke in ...patients with AF. We aimed to examine the safety and efficacy of rivaroxaban vs warfarin in patients with nonvalvular AF and DM in a prespecified secondary analysis of the ROCKET AF trial. Methods We stratified the ROCKET AF population by DM status, assessed associations with risk of outcomes by DM status and randomized treatment using Cox proportional hazards models, and tested for interactions between randomized treatments. For efficacy, primary outcomes were stroke (ischemic or hemorrhagic) or non–central nervous system embolism. For safety, the primary outcome was major or nonmajor clinically relevant bleeding. Results The 5,695 patients with DM (40%) in ROCKET AF were younger, were more obese, and had more persistent AF, but fewer had previous stroke (the CHADS2 score includes DM and stroke). The relative efficacy of rivaroxaban and warfarin for prevention of stroke and systemic embolism was similar in patients with (1.74 vs 2.14/100 patient-years, hazard ratio HR 0.82) and without (2.12 vs 2.32/100 patient-years, HR 0.92) DM (interaction P = .53). The safety of rivaroxaban vs warfarin regarding major bleeding (HRs 1.00 and 1.12 for patients with and without DM, respectively; interaction P = .43), major or nonmajor clinically relevant bleeding (HRs 0.98 and 1.09; interaction P = .17), and intracerebral hemorrhage (HRs 0.62 and 0.72; interaction P = .67) was independent of DM status. Adjusted exploratory analyses suggested 1.3-, 1.5-, and 1.9-fold higher 2-year rates of stroke, vascular mortality, and myocardial infarction in DM patients. Conclusions and Relevance The relative efficacy and safety of rivaroxaban vs warfarin was similar in patients with and without DM, supporting use of rivaroxaban as an alternative to warfarin in diabetic patients with AF.
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