Thermoregulated gas transport through electrospun nanofiber membranes

Thermoregulation of gas transport using electrospun fiber membranes is demonstrated experimentally for the first time. The fiber membranes comprise three layers: a middle layer of electrospun polystyrene sandwiched between two outer layers of electrospun cellulose acetate mat as supports, bonded together by hot pressing. The electrospun polystyrene layer serves as a phase change material that blocks transport of gases though the membrane when the fibers de-vitrify. The membrane exhibited a reduction in oxygen flux at temperatures in excess of 140 °C. Using a blend of polysulfone and polystyrene resulted in an upward shift of the transition temperature to 250 °C. Modeling of transport was performed to estimate the impact of the morphological properties of the membranes such as tortuosity, fiber diameter, and porosity.Philip Morris Internationa

Mechanisms and modeling of white layer formation in orthogonal machining of steels

The research objectives of this thesis are as follows: (1) Investigate the effects of carbon content, alloying, and heat treatment of steels on white layer formation, (2) Prove/disprove that the temperature for phase transformation in machining is the same as the nominal phase transformation temperature of the steel, (3) Quantify the contributions of thermal and mechanical effects to white layer generation in machining, (4) Develop a semi-empirical procedure for prediction of white layer formation that accounts for both thermal and mechanical effects. These research objectives are realized through experimental and modeling efforts on steels. Depth and hardness measurements of the white layers formed in steels show the importance of heat treatment and carbon content on white layer formation. Measurements of workpiece surface temperature and X-Ray Diffraction characterization of the machined surfaces show that phase transformation occurs below the nominal As temperature suggesting that mechanical effects play an important role in white layer formation. The maximum workpiece surface temperature, the effective stress, and plastic strain on the workpiece surface are measured and/or calculated and shown to affect the white layer depth and amount of retained austenite. A semi-empirical procedure is developed by correlating the maximum workpiece temperature and the unit thrust force increase with white layer formation.Ph.D.Committee Chair: Shreyes Melkote; Committee Member: Hamid Garmestani; Committee Member: Paul Griffin; Committee Member: Steven Liang; Committee Member: Thomas Kurfes

Robust SVD Made Easy: A fast and reliable algorithm for large-scale data analysis

The singular value decomposition (SVD) is a crucial tool in machine learning and statistical data analysis. However, it is highly susceptible to outliers in the data matrix. Existing robust SVD algorithms often sacrifice speed for robustness or fail in the presence of only a few outliers. This study introduces an efficient algorithm, called Spherically Normalized SVD, for robust SVD approximation that is highly insensitive to outliers, computationally scalable, and provides accurate approximations of singular vectors. The proposed algorithm achieves remarkable speed by utilizing only two applications of a standard reduced-rank SVD algorithm to appropriately scaled data, significantly outperforming competing algorithms in computation times. To assess the robustness of the approximated singular vectors and their subspaces against data contamination, we introduce new notions of breakdown points for matrix-valued input, including row-wise, column-wise, and block-wise breakdown points. Theoretical and empirical analyses demonstrate that our algorithm exhibits higher breakdown points compared to standard SVD and its modifications. We empirically validate the effectiveness of our approach in applications such as robust low-rank approximation and robust principal component analysis of high-dimensional microarray datasets. Overall, our study presents a highly efficient and robust solution for SVD approximation that overcomes the limitations of existing algorithms in the presence of outliers

Delirium prevention and treatment in the emergency department (ED): A systematic review protocol

INTRODUCTION: Delirium is a dangerous syndrome of acute brain dysfunction that is common in the emergency department (ED), especially among the geriatric population. Most systematic reviews of interventions for delirium prevention and treatment have focused on inpatient settings. Best practices of effective delirium care in ED settings have not been established. The primary objective of this study is to identify pharmacologic and non-pharmacologic interventions as applied by physicians, nursing staff, pharmacists and other ED personnel to prevent incident delirium and to shorten the severity and duration of prevalent delirium in a geriatric population within the ED. METHODS AND ANALYSIS: Searches using subject headings and keywords will be conducted from database inception through June 2020 in MEDLINE, EMBASE, Web of Science, PsychINFO, CINAHL, ProQuest Dissertations and Theses Global and Cochrane CENTRAL as well as grey literature. Database searches will not be limited by date or language. Two reviewers will identify studies describing any interventions for delirium prevention and/or treatment in the ED. Disagreements will be settled by a third reviewer. Pooled data analysis will be performed where possible using Review Manager. Risk ratios and weighted difference of means will be used for incidence of delirium and other binary outcomes related to delirium, delirium severity or duration of symptoms, along with 95% CIs. Heterogeneity will be measured by calculating ETHICS AND DISSEMINATION: This is a systematic review of previously conducted research; accordingly, it does not constitute human subjects research needing ethics review. This review will be prepared as a manuscript and submitted for publication to a peer-reviewed journal, and the results will be presented at conferences. PROSPERO TRIAL REGISTRATION NUMBER: CRD42020169654

Learning to Quantize Deep Networks by Optimizing Quantization Intervals with Task Loss

Reducing bit-widths of activations and weights of deep networks makes it efficient to compute and store them in memory, which is crucial in their deployments to resource-limited devices, such as mobile phones. However, decreasing bit-widths with quantization generally yields drastically degraded accuracy. To tackle this problem, we propose to learn to quantize activations and weights via a trainable quantizer that transforms and discretizes them. Specifically, we parameterize the quantization intervals and obtain their optimal values by directly minimizing the task loss of the network. This quantization-interval-learning (QIL) allows the quantized networks to maintain the accuracy of the full-precision (32-bit) networks with bit-width as low as 4-bit and minimize the accuracy degeneration with further bit-width reduction (i.e., 3 and 2-bit). Moreover, our quantizer can be trained on a heterogeneous dataset, and thus can be used to quantize pretrained networks without access to their training data. We demonstrate the effectiveness of our trainable quantizer on ImageNet dataset with various network architectures such as ResNet-18, -34 and AlexNet, on which it outperforms existing methods to achieve the state-of-the-art accuracy

Removal of volatile organic compounds from air using activated carbon impregnated cellulose acetate electrospun mats

Volatile organic compounds (VOCs) are released from various sources and are unsafe for human health. Porous materials are promising candidates for the adsorption of VOCs owing to their increased ratio of surface area to volume. In this study, activated carbon (AC) impregnated cellulose acetate (CA) electrospun mats were synthesized using electrospinning for the removal of VOCs from the air mixture of ACs, and CA solution was electrospun at different proportions (5%, 10%, and 15%) in a single nozzle system. The different AC amounts in the electrospun mats were distributed within the AC fibers. The adsorption capacities were measured for acetone, benzene, and dichloromethane, using quartz crystal microbalance. The results elicited an increasing adsorption capacity trend as a function of the impregnation of ACs in the electrospun mats, while their capacities increased as a function of the AC concentration. Dichloromethane resulted in a faster adsorption process than acetone and benzene owing to its smaller molecular size. VOCs were desorbed with the N-2 gas purging, while VOCs were adsorbed at higher temperatures owing to the increased vapor pressures. The adsorption analysis using Dubinin-Astakhov equation showed that dichloromethane is more strongly adsorbed on mats

Reducing fine-grain communication overhead in multithread code generation for heterogeneous MPSoC

Heterogeneous MPSoCs present unique opportunities for emerging embedded applications, which require both high-performance and programmability. Although, software programming for these MPSoC architectures requires tedious and error-prone tasks, thereby automatic code generation tools are required. A code generation method based on fine-grain specification can provide more design space and optimization opportunities, such as exploiting fine-level parallelism and more efficient partitions. However, when partitioned, fine-grain models may require a large number of inter-processor communications, decreasing the overall system performance. This paper presents a Simulink-based multithread code generation method, which applies Message Aggregation optimization technique to reduce the number of interprocessor communications. This technique reduces the communication overheads in terms of execution time by reduction on the number of messages exchanged and in terms of memory size by the reduction on the number of channels. The paper also presents experiment results for one multimedia application, showing performance improvements and memory reduction obtained with Message Aggregation technique

Small-molecule inhibitors of ferrochelatase are antiangiogenic agents

Activity of the heme synthesis enzyme ferrochelatase (FECH) is implicated in multiple diseases. In particular, it is a mediator of neovascularization in the eye and thus an appealing therapeutic target for preventing blindness. However, no drug-like direct FECH inhibitors are known. Here, we set out to identify small-molecule inhibitors of FECH as potential therapeutic leads using a high-throughput screening approach to identify potent inhibitors of FECH activity. A structure-activity relationship study of a class of triazolopyrimidinone hits yielded drug-like FECH inhibitors. These compounds inhibit FECH in cells, bind the active site in cocrystal structures, and are antiangiogenic in multiple in vitro assays. One of these promising compounds was antiangiogenic in vivo in a mouse model of choroidal neovascularization. This foundational work may be the basis for new therapeutic agents to combat not only ocular neovascularization but also other diseases characterized by FECH activity

Troponin Is Unrelated to Outcomes in Heart Failure Patients Discharged From the Emergency Department

Background: Prior data has demonstrated increased mortality in hospitalized patients with acute heart failure (AHF) and troponin elevation. No data has specifically examined the prognostic significance of troponin elevation in patients with AHF discharged after emergency department (ED) management. Objective: Evaluate the relationship between troponin elevation and outcomes in patients with AHF who are treated and released from the ED. Methods: This was a secondary analysis of the Get with the Guidelines to Reduce Disparities in AHF Patients Discharged from the ED (GUIDED-HF) trial, a randomized, controlled trial of ED patients with AHF who were discharged. Patients with elevated conventional troponin not due to acute coronary syndrome (ACS) were included. Our primary outcome was a composite endpoint: time to 30-day cardiovascular death and/or heart failure-related events. Results: Of the 491 subjects included in the GUIDED-HF trial, 418 had troponin measured during the ED evaluation and 66 (16%) had troponin values above the 99th percentile. Median age was 63 years (interquartile range, 54-70), 62% (n = 261) were male, 63% (n = 265) were Black, and 16% (n = 67) experienced our primary outcome. There were no differences in our primary outcome between those with and without troponin elevation (12/66, 18.1% vs 55/352, 15.6%; P = 0.60). This effect was maintained regardless of assignment to usual care or the intervention arm. In multivariable regression analysis, there was no association between our primary outcome and elevated troponin (hazard ratio, 1.00; 95% confidence interval, 0.49-2.01, P = 0.994). Conclusion: If confirmed in a larger cohort, these findings may facilitate safe ED discharge for a group of patients with AHF without ACS when an elevated troponin is the primary reason for admission