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Autohesion is a unique class of adhesion that enables the bonding of two identical surfaces by establishing intimate contact at interfaces. Creating intimacy between two identical surfaces poses a challenging task, often constrained by the presence of surface roughness and chemical heterogeneity. To surmount this challenge, we document a variety of autohesive traits in polypropylene-based meltblown nonwovens, accomplished through a facile, scalable, energy-efficient, and cost-effective ultrasonic bonding process. The mean work of autohesion for a single polypropylene bond, serving as a figure of merit, has been computed by extending the classical Johnson−Kendall−Roberts (JKR) theory by factoring in peel strength along with key fiber and structural parameters of nonwoven materials. Achieving a high figure of merit in ultrasonically bonded nonwovens hinges on the synergistic interplay of key process parameters, including static force, power, and welding speed, with the fiber and structural properties acting in concert. In this regard, peel-off force analysis has also been conducted on a series of twenty-seven ultrasonically bonded meltblown nonwovens prepared using a 33 full factorial design by systematically varying process parameters (static force, power, and welding speed) across three levels and extension rate. X-ray microcomputed tomography (microCT) analysis has been performed on select ultrasonically bonded nonwoven samples to discern their bulk characteristics. A broad spectrum of mean work of autohesion for a single polypropylene bond, ranging from 1.88 to 9.93 J/m², has been ascertained by modulating key process parameters.

Abstract Filtering facepiece respirators (FFRs) provide effective protection against diseases spread through airborne infectious droplets and particles. The widespread use of FFRs during the COVID-19 pandemic has not only led to supply shortages, but the disposal of single-use facemasks also threatens the environment with a new kind of plastic pollution. While limited reuse of filtering facepiece respirators has been permitted as a crisis capacity strategy, there are currently no standard test methods available for decontamination before their repeated use. The decontamination of respirators can compromise the structural and functional integrity by reducing the filtration efficiency and breathability. Digital segmentation of X-ray microcomputed tomography (microCT) scans of the meltblown nonwoven layers of a specific N95 respirator model (Venus-4400) after treatment with one and five cycles of liquid hydrogen peroxide, ultraviolet radiation, moist heat, and aqueous soap solution enabled us to perform filtration simulations of decontaminated respirators. The computed filtration efficiencies for 0.3 µm particles agreed well with experimental measurements, and the distribution of particle penetration depths was correlated with the structural changes resulting from decontamination. The combination of X-ray microCT imaging with numerical simulations thus provides a strategy for quantitative evaluation of the effectiveness of decontamination treatments for a specific respirator model.

Objective: At a large public university, we aimed to evaluate an intervention designed to increase serogroup B meningococcal (MenB) vaccine uptake and awareness. Methods: Using a pretest-posttest design with a double posttest, we evaluated an intervention conducted by a local foundation and the Florida Department of Health that distributed MenB vaccine on campus and conducted an educational campaign. Prior to intervention activities, we recruited students to complete a survey about their MenB knowledge and attitudes. For survey participants who provided contact information, we sent two follow-up surveys and assessed MenB vaccine records. We used chi-square tests, adjusted for nonindependence, to compare preintervention to postintervention (three-month and one-year) vaccination and attitudes. Results: Among the 686 students with accessible vaccine records, MenB vaccine initiation increased 9% (from 24% to 33%) and completion increased 8% (from 13% to 21%) from before the intervention to one year after the intervention. When restricting to students who completed the relevant follow-up surveys, the percentage of students who heard of the MenB vaccine increased by 15% (p > .001) from before the intervention to three months after (n = 188 students) and maintained a 10% increase (p > .001) one year after the intervention (n = 261 students). Among students that heard of the MenB vaccine, the percentage of students who thought they needed the MenB vaccine even though they received the MenACWY increased 14% (p = .03) by the three-month postintervention survey and up to 18% by the one-year follow-up (p = .002). Conclusions: A university-wide, on-campus vaccination and educational campaign increased college students’ MenB vaccine initiation, completion, and knowledge. Clinicaltrials.gov ID: NCT02975596.

Investigations of the “fat-face” illusion have unanimously agreed that the illusion is face-specific. Here, we offer several manipulations to highlight that the fat-face illusion is not restricted to the bottom image, isn’t a property of internal features, facial contour/texture, and in general isn’t even specific to faces. We propose the axis of horizontal asymmetry account to contextualize fat-face illusion as a geometry-led illusion.

Simultaneous hemorrhagic and ischemic strokes have been previously reported in the literature. Typically, these occur in patients secondary to dialysis, cerebral amyloid angiopathy, or thrombotic thrombocytopenic purpura. 1, 2, 3 However, this is the unique case of a 62-year-old Asian female who presented with a hemorrhagic stroke suspected to be secondary to refractory hypertension from intracranial large vessel atherosclerotic flow limiting stenosis, with rapid subsequent large vessel occlusion and ischemic stroke. Questions arise such as ideal blood pressure parameters for dual management, timeliness of computed tomography angiography imaging in the emergency department for detection of large vessel occlusion during intracranial hemorrhage, and subsequent selection of treatment plan in the dual-lesion patient population.

Fiber orientation is a key parameter affecting the geometrical, hydraulic and mechanical properties of nonwoven materials. The effect of fiber orientation on the pore size has been experimentally investigated based on air‐laid, parallel‐laid, and cross‐laid structures following through‐air bonding. It was evident that there is a discernible difference between the mean flow and maximum pore sizes of these nonwoven materials. The influence on pore size was further elucidated by evaluating experimental and theoretical models based on sieving‐percolation pore network theory including a model that incorporates directional parameter to account for the effect of fiber orientation. It was established that good agreement with experimental data can be obtained using such a model. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [ABSTRACT FROM AUTHOR]