Entity

Time filter

Source Type


Wang X.,Harbin Institute of Technology | Lyu J.,Northwestern Polytechnical University | Kotov N.A.,University of Michigan | Kotov N.A.,Michigan Center for Integrative Research in Critical Care
ACS Nano | Year: 2016

Beam steering devices represent an essential part of an advanced optics toolbox and are needed in a spectrum of technologies ranging from astronomy and agriculture to biosensing and networked vehicles. Diffraction gratings with strain-tunable periodicity simplify beam steering and can serve as a foundation for light/laser radar (LIDAR/LADAR) components of robotic systems. However, the mechanical properties of traditional materials severely limit the beam steering angle and cycle life. The large strain applied to gratings can severely impair the device performance both in respect of longevity and diffraction pattern fidelity. Here, we show that this problem can be resolved using micromanufactured kirigami patterns from thin film nanocomposites based on high-performance stiff plastics, metals, and carbon nanotubes, etc. The kirigami pattern of microscale slits reduces the stochastic concentration of strain in stiff nanocomposites including those made by layer-by-layer assembly (LBL). The slit patterning affords reduction of strain by 2 orders of magnitude for stretching deformation and consequently enables reconfigurable optical gratings with over a 100% range of period tunability. Elasticity of the stiff nanocomposites and plastics makes possible cyclic reconfigurability of the grating with variable time constant that can also be referred to as 4D kirigami. High-contrast, sophisticated diffraction patterns with as high as fifth diffraction order can be obtained. The angular range of beam steering can be as large as 6.5° for a 635 nm laser beam compared to ∼1° in surface-grooved elastomer gratings and ∼0.02° in MEMS gratings. The versatility of the kirigami patterns, the diversity of the available nanocomposite materials, and their advantageous mechanical properties of the foundational materials open the path for engineering of reconfigurable optical elements in LIDARs essential for autonomous vehicles and other optical devices with spectral range determined by the kirigami periodicity. © 2016 American Chemical Society. Source


Hsu Y.-Y.,University of Colorado at Boulder | Bortz D.M.,University of Colorado at Boulder | Younger J.G.,Michigan Center for Integrative Research in Critical Care | Younger J.G.,University of Michigan
Journal of Innate Immunity | Year: 2013

Opsonization and anaphylatoxin production are early events in the innate response to bacterial pathogens. Opsonization alone is frequently not lethal and production of anaphy-latoxins, especially C5a, allows for recruitment of cellular defenses. Complement biochemistry is extensively studied and computational models have been reported previously. However, a critical feature of complement-mediated attack is its spatial dependence: diffusion of mediators into and away from a bacterium is central to understanding C5a generation. Spatial dependence is especially important in biofilms, where diffusion limitation is crucial to bacterial counterdefense. Here we develop a model of opsonization and C5a production in the presence of a common blood-borne pathogen, Staphylococcus epidermidis. Our results indicate that when complement attacks a single cell, diffusion into the extracellular polymeric substance (EPS) is complete within 10 ms and that production of C5a peaks over the next 15 min. When longer diffusion lengths (as in an EPS-rich biofilm) are incorporated, diffusion limitation appears such that the intensity and duration of C5a production is increased. However, the amount of C5a produced under several likely clinical scenarios where single cells or sparse biofilms are present is below the kD of the C5a receptor suggesting that complement activation by a single bacterium may be difficult to detect when diffusion is taken into account. Copyright © 2013 S. Karger AG, Basel. Source


Dehghannasiri R.,Texas A&M University | Soroushmehr S.M.R.,Michigan Center for Integrative Research in Critical Care | Shirani S.,McMaster University
2014 IEEE International Conference on Image Processing, ICIP 2014 | Year: 2014

In some applications such as digital video broadcasting, video is transmitted over a low capacity channel with lower frame rates. The lower the frame rate, the jerkier or unevener the video motion would be noticed. To solve this problem, frame rate up conversion (FRUC) is employed to increase the frame rate. In this paper, we propose a new FRUC method using the nonlocal-means estimator. In this method, a pixel is reconstructed as a weighted linear combination of pixel pairs in its adjacent frames. The pixels of each pair are temporally symmetric from the view point of the pixel being interpolated. The weights are calculated based on the self-similarity assumption. To reduce the computational complexity, we calculate the weights of linear combination for each super-pixel. Experimental results show the superior performance of our proposed method in comparison to the existing methods. © 2014 IEEE. Source


Aghazadeh B.S.,Massachusetts Eye and Ear Infirmary | Aghazadeh B.S.,Worcester Polytechnic Institute | Ansari S.,Virginia Commonwealth University | Pidaparti R.,Virginia Commonwealth University | Najarian K.,Michigan Center for Integrative Research in Critical Care
Biomedical Engineering Letters | Year: 2013

Purpose: This paper aims to estimate the intracranial pressure (ICP) in patients with traumatic brain injuries (TBI) noninvasively using directional features obtained from the texture of brain CT image and support vector regression (SVR) method. Methods: A fully anisotropic Morlet wavelet transform is performed on brain CT images and optimal feature vectors have been extracted to classify the images into two groups of mild and severe TBI. Genetic algorithms with the fitness functions of support vector machines (SVM) classification accuracy rates have been used to find the optimal feature vector. Finally, SVR is implemented to estimate the ICP of patients with TBI. The results are compared to the ones obtained using Dual Tree complex wavelet transform based directional features. Results: Features obtained from anisotropic continuous complex wavelet transform are shown to be effective in separating data from two classes of mild and severe TBI. The highest classification accuracy rate of 94.43 percent is achieved. Also, using SVR, the ICP estimation results demonstrate that the proposed algorithm yields excellent performance with a mean absolute error of 4.25 mmHg compared to Dual Tree complex wavelet transform features with the mean absolute error of 5.48 mmHg. Conclusions: The severity of TBI is assessed non-invasively using brain CT images, and the directional textural features of brain tissue. The proposed algorithm using anisotropic Morlet wavelet features, GA-SVM based feature selection and SVR methods achieves an excellent performance in ICP estimation for TBI severity assessment. © 2013 Korean Society of Medical and Biological Engineering and Springer. Source


McGuffie M.J.,Michigan Center for Integrative Research in Critical Care | McGuffie M.J.,University of Michigan | Hong J.,China Pharmaceutical University | Glynos E.,University of Michigan | And 5 more authors.
Nanomedicine: Nanotechnology, Biology, and Medicine | Year: 2016

Despite a decade of engineering and process improvements, bacterial infection remains the primary threat to implanted medical devices. Zinc oxide nanoparticles (ZnO-NPs) have demonstrated antimicrobial properties. Their microbial selectivity, stability, ease of production, and low cost make them attractive alternatives to silver NPs or antimicrobial peptides. Here we sought to (1) determine the relative efficacy of ZnO-NPs on planktonic growth of medically relevant pathogens; (2) establish the role of bacterial surface chemistry on ZnO-NP effectiveness; (3) evaluate NP shape as a factor in the dose-response; and (4) evaluate layer-by-layer (LBL) ZnO-NP surface coatings on biofilm growth. ZnO-NPs inhibited bacterial growth in a shape-dependent manner not previously seen or predicted. Pyramid shaped particles were the most effective and contrary to previous work, larger particles were more effective than smaller particles. Differential susceptibility of pathogens may be related to their surface hydrophobicity. LBL ZnO-NO coatings reduced staphylococcal biofilm burden by >. 95%. From the Clinical Editor: The use of medical implants is widespread. However, bacterial colonization remains a major concern. In this article, the authors investigated the use of zinc oxide nanoparticles (ZnO-NPs) to prevent bacterial infection. They showed in their experiments that ZnO-NPs significantly inhibited bacterial growth. This work may present a new alternative in using ZnO-NPs in medical devices. © 2015 Elsevier Inc. Source

Discover hidden collaborations