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Articles 1 - 17 of 17
Full-Text Articles in Engineering
Quantitative, Spectrally-Resolved Intraoperative Fluorescence Imaging, Pablo A. Valdés, Frederic Leblond, Valerie L. Jacobs, Brian C. Wilson, Keith D. Paulsen, David W. Roberts
Quantitative, Spectrally-Resolved Intraoperative Fluorescence Imaging, Pablo A. Valdés, Frederic Leblond, Valerie L. Jacobs, Brian C. Wilson, Keith D. Paulsen, David W. Roberts
Dartmouth Scholarship
Intraoperative visual fluorescence imaging (vFI) has emerged as a promising aid to surgical guidance, but does not fully exploit the potential of the fluorescent agents that are currently available. Here, we introduce a quantitative fluorescence imaging (qFI) approach that converts spectrally-resolved data into images of absolute fluorophore concentration pixel-by-pixel across the surgical field of view (FOV). The resulting estimates are linear, accurate, and precise relative to true values, and spectral decomposition of multiple fluorophores is also achieved. Experiments with protoporphyrin IX in a glioma rodent model demonstrate in vivo quantitative and spectrally-resolved fluorescence imaging of infiltrating tumor margins for the …
Characterization Of Xylan Utilization And Discovery Of A New Endoxylanase In Thermoanaerobacterium Saccharolyticum Through Targeted Gene Deletions, Kara K. Podkaminer, Adam M. Guss, Heather L. Trajano, David A. Hogsett, Lee R. Lynd
Characterization Of Xylan Utilization And Discovery Of A New Endoxylanase In Thermoanaerobacterium Saccharolyticum Through Targeted Gene Deletions, Kara K. Podkaminer, Adam M. Guss, Heather L. Trajano, David A. Hogsett, Lee R. Lynd
Dartmouth Scholarship
The economical production of fuels and commodity chemicals from lignocellulose requires the utilization of both the cellulose and hemicellulose fractions. Xylanase enzymes allow greater utilization of hemicellulose while also increasing cellulose hydrolysis. Recent metabolic engineering efforts have resulted in a strain of Thermoanaerobacterium saccharolyticum that can convert C5 and C6 sugars, as well as insoluble xylan, into ethanol at high yield. To better understand the process of xylan solubilization in this organism, a series of targeted deletions were constructed in the homoethanologenic T. saccharolyticum strain M0355 to characterize xylan hydrolysis and xylose utilization in this organism. While the deletion of …
Image-Based Quantification Of Benzoporphyrin Derivative Uptake, Localization, And Photobleaching In 3d Tumor Models, For Optimization Of Pdt Parameters, Michael D. Glidden, Jonathan P. Celli, Iqbal Massodi, Imran Rizvi, Brian Pogue, Tayyaba Hasan
Image-Based Quantification Of Benzoporphyrin Derivative Uptake, Localization, And Photobleaching In 3d Tumor Models, For Optimization Of Pdt Parameters, Michael D. Glidden, Jonathan P. Celli, Iqbal Massodi, Imran Rizvi, Brian Pogue, Tayyaba Hasan
Dartmouth Scholarship
Photodynamic therapy (PDT) is a light-based treatment modality in which wavelength specific activation of a photosensitizer (PS) generates cytotoxic response in the irradiated region. PDT response is critically dependent on several parameters including light dose, PS dose, uptake time, fluence rate, and the mode of light delivery. While the systematic optimization of these treatment parameters can be complex, it also provides multiple avenues for en- hancement of PDT efficacy under diverse treatment conditions, provided that a rational framework is established to quantify the impact of parameter selection upon treatment re- sponse. Here we present a theranostic technique, combining the inherent …
Multichannel Diffuse Optical Raman Tomography For Bone Characterization In Vivo: A Phantom Study, Jennifer-Lynn H. Demers, Scott C. Davis, Brian W. Pogue, Michael D. Morris
Multichannel Diffuse Optical Raman Tomography For Bone Characterization In Vivo: A Phantom Study, Jennifer-Lynn H. Demers, Scott C. Davis, Brian W. Pogue, Michael D. Morris
Dartmouth Scholarship
Raman spectroscopy is used to gather information on the mineral and organic components of bone tissue to analyze their composition. By measuring the Raman signal of bone through spatially offset Raman spectroscopy the health of the bone can be determined. We’ve customized a system with 8 collection channels that consist of individual fibers, which are coupled to separate spectrometers and cooled CCDs. This parallel detection system was used to scan gelatin phantoms with Teflon inclusions of two sizes. Raman signals were decoupled from the autofluorescence background using channel specific polynomial fitting. Images with high contrast to background ratios of Raman …
A Digital X-Ray Tomosynthesis Coupled Near Infrared Spectral Tomography System For Dual-Modality Breast Imaging, Venkataramanan Krishnaswamy, Kelly E. Michaelsen, Brian W. Pogue, Steven P. Poplack, Ian Shaw, Ken Defrietas, Ken Brooks, Keith D. Paulsen
A Digital X-Ray Tomosynthesis Coupled Near Infrared Spectral Tomography System For Dual-Modality Breast Imaging, Venkataramanan Krishnaswamy, Kelly E. Michaelsen, Brian W. Pogue, Steven P. Poplack, Ian Shaw, Ken Defrietas, Ken Brooks, Keith D. Paulsen
Dartmouth Scholarship
A Near Infrared Spectral Tomography (NIRST) system has been developed and integrated into a commercial Digital Breast Tomosynthesis (DBT) scanner to allow structural and functional imaging of breast in vivo. The NIRST instrument uses an 8-wavelength continuous wave (CW) laser-based scanning source assembly and a 75-element silicon photodiode solid-state detector panel to produce dense spectral and spatial projection data from which spectrally constrained 3D tomographic images of tissue chromophores are produced. Integration of the optical imaging system into the DBT scanner allows direct co-registration of the optical and DBT images, while also facilitating the synergistic use of x-ray contrast as …
Measurement Of The Oxidation State Of Mitochondrial Cytochrome C From The Neocortex Of The Mammalian Brain, Y. Sakata, M. Abajian, M. O. Ripple, R. Springett
Measurement Of The Oxidation State Of Mitochondrial Cytochrome C From The Neocortex Of The Mammalian Brain, Y. Sakata, M. Abajian, M. O. Ripple, R. Springett
Dartmouth Scholarship
Diffuse optical remission spectra from the mammalian neocortex at visible wavelengths contain spectral features originating from the mitochondria. A new algorithm is presented, based on analytically relating the first differential of the attenuation spectrum to the first differential of the chromophore spectra, that can separate and calculate the oxidation state of cytochrome c as well as the absolute concentration and saturation of hemoglobin. The algorithm is validated in phantoms and then tested on the neocortex of the rat during an anoxic challenge. Implementation of the algorithm will provide detailed information of mitochondrial oxygenation and mitochondrial function in physiological studies of …
Integrated Analysis Of Hydrothermal Flow Through Pretreatment, Veronique Archambault-Leger, Xiongjun Shao, Lee R. Lynd
Integrated Analysis Of Hydrothermal Flow Through Pretreatment, Veronique Archambault-Leger, Xiongjun Shao, Lee R. Lynd
Dartmouth Scholarship
Background:
The impact of hydrothermal flowthrough (FT) pretreatment severity on pretreatment and solubilization performance metrics was evaluated for three milled feedstocks (corn stover, bagasse, and poplar) and two conversion systems (simultaneous saccharification and fermentation using yeast and fungal cellulase, and fermentation by Clostridium thermocellum).
Results:
Compared to batch pretreatment, FT pretreatment consistently resulted in higher XMG recovery, higher removal of non-carbohydrate carbon and higher glucan solubilization by simultaneous saccharification and fermentation (SSF). XMG recovery was above 90% for FT pretreatment below 4.1 severity but decreased at higher severities, particularly for bagasse. Removal of non-carbohydrate carbon during FT pretreatment increased …
Joint Diagonalization Applied To The Detection And Discrimination Of Unexploded Ordnance, Fridon Shubitidze, Juan Pablo Fernández, Irma Shamatava, Benjamin Barrowes, Kevin O’Neill
Joint Diagonalization Applied To The Detection And Discrimination Of Unexploded Ordnance, Fridon Shubitidze, Juan Pablo Fernández, Irma Shamatava, Benjamin Barrowes, Kevin O’Neill
Dartmouth Scholarship
Efforts to discriminate buried unexploded ordnance from harmless surrounding clutter are often hampered by the uncertainty in the number of buried targets that produce a given detected signal. We present a technique that helps determine that number with no need for data inversion. The procedure is based on the joint diagonalization of a set of multistatic response (MSR) matrices measured at different time gates by a time-domain electromagnetic induction sensor. In particular, we consider the Naval Research Laboratory’s Time-Domain Electromagnetic Multisensor Towed Array Detection System (TEMTADS), which consists of a 5×5 square grid of concentric transmitter/receiver pairs. The diagonalization process …
Using Life Cycle Assessment Methods To Guide Architectural Decision-Making For Sustainable Prefabricated Modular Buildings, Jeremy Faludi, Michael Lepech, George Loisos
Using Life Cycle Assessment Methods To Guide Architectural Decision-Making For Sustainable Prefabricated Modular Buildings, Jeremy Faludi, Michael Lepech, George Loisos
Dartmouth Scholarship
Within this work, life cycle assessment modeling is used to determine top design priorities and quantitatively inform sustainable design decision-making for a prefabricated modular building. A case-study life-cycle assessment was performed for a 5,000 ft2 prefabricated commercial building constructed in San Francisco, California, and scenario analysis was run examining the life cycle environmental impacts of various energy and material design substitutions, and a structural design change. Results show that even for a highly energy-efficient modular building, the top design priority is still minimizing operational energy impacts, since this strongly dominates the building life cycle's environmental impacts. However, as an …
Ethanol And Anaerobic Conditions Reversibly Inhibit Commercial Cellulase Activity In Thermophilic Simultaneous Saccharification And Fermentation (Tssf), Kara K. Podkaminer, William R. Kenealy, Christopher D. Herring, David A. Hogsett, Lee R. Lynd
Ethanol And Anaerobic Conditions Reversibly Inhibit Commercial Cellulase Activity In Thermophilic Simultaneous Saccharification And Fermentation (Tssf), Kara K. Podkaminer, William R. Kenealy, Christopher D. Herring, David A. Hogsett, Lee R. Lynd
Dartmouth Scholarship
A previously developed mathematical model of low solids thermophilic simultaneous saccharification and fermentation (tSSF) with Avicel was unable to predict performance at high solids using a commercial cellulase preparation (Spezyme CP) and the high ethanol yield Thermoanaerobacterium saccharolyticum strain ALK2. The observed hydrolysis proceeded more slowly than predicted at solids concentrations greater than 50 g/L Avicel. Factors responsible for this inaccuracy were investigated in this study.
Computational Design And Characterization Of A Temperature-Sensitive Plasmid Replicon For Gram Positive Thermophiles, Daniel G. Olson, Lee R. Lynd
Computational Design And Characterization Of A Temperature-Sensitive Plasmid Replicon For Gram Positive Thermophiles, Daniel G. Olson, Lee R. Lynd
Dartmouth Scholarship
Temperature-sensitive (Ts) plasmids are useful tools for genetic engineering, but there are currently none compatible with the gram positive, thermophilic, obligate anaerobe, Clostridium thermocellum. Traditional mutagenesis techniques yield Ts mutants at a low frequency, and therefore requires the development of high-throughput screening protocols, which are also not available for this organism. Recently there has been progress in the development of computer algorithms which can predict Ts mutations. Most plasmids currently used for genetic modification of C. thermocellum are based on the replicon of plasmid pNW33N, which replicates using the RepB replication protein. To address this problem, we set out …
Improved Tumor Contrast Achieved By Single Time Point Dual-Reporter Fluorescence Imaging, Kenneth M. Tichauer, Kimberley S. Samkoe, Kristian J. Sexton, Jason R. Gunn, Tayyaba Hasan, Brian W. Pogue
Improved Tumor Contrast Achieved By Single Time Point Dual-Reporter Fluorescence Imaging, Kenneth M. Tichauer, Kimberley S. Samkoe, Kristian J. Sexton, Jason R. Gunn, Tayyaba Hasan, Brian W. Pogue
Dartmouth Scholarship
In this study, we demonstrate a method to quantify biomarker expression that uses an exogenous dual-reporter imaging approach to improve tumor signal detection. The uptake of two fluorophores, one nonspecific and one targeted to the epidermal growth factor receptor (EGFR), were imaged at 1 h in three types of xenograft tumors spanning a range of EGFR expression levels (n = 6 in each group). Using this dual-reporter imaging methodology, tumor contrast-to-noise ratio was amplified by >6 times at 1 h postinjection and >2 times at 24 h. Furthermore, by as early as 20 min postinjection, the dual-reporter imaging signal …
Scattering Phase Function Spectrum Makes Reflectance Spectrum Measured From Intralipid Phantoms And Tissue Sensitive To The Device Detection Geometry, S. C. Kanick, V. Krishnaswamy, U. A. Gamm, H. J.C.M Sterenborg, D. J. Robinson, A. Amelink, B. W. Pogue
Scattering Phase Function Spectrum Makes Reflectance Spectrum Measured From Intralipid Phantoms And Tissue Sensitive To The Device Detection Geometry, S. C. Kanick, V. Krishnaswamy, U. A. Gamm, H. J.C.M Sterenborg, D. J. Robinson, A. Amelink, B. W. Pogue
Dartmouth Scholarship
Reflectance spectra measured in Intralipid (IL) close to the source are sensitive to wavelength -dependent changes in reduced scattering coefficient (μs′)and scattering phase function (PF). Experiments and simulations were performed using device designs with either single or separate optical fibers for delivery and collection of light in varying concentrations of IL. Spectral reflectance is not consistentl y linear with varying IL concentration, with PF -dependent effects observed for single fiber devices with diameters smaller than ten transport lengths and for separate source- detector devices that collected light at less than half of a transport length from the source. …
Developing Unique Engineering Solutions To Improve Patient Safety, Bradley Watts, Douglas Van Citters, Brian Shiner, Peter Mills
Developing Unique Engineering Solutions To Improve Patient Safety, Bradley Watts, Douglas Van Citters, Brian Shiner, Peter Mills
Dartmouth Scholarship
Many efforts to improve healthcare safety have focused on redesigning processes of care or retraining clinicians. Far less attention has been focused on the use of new technologies to improve safety. We present the results of a unique collaboration between the VA National Center for Patient Safety (NCPS) and the Thayer School of Engineering at Dartmouth College. Each year, the NCPS identifies safety problems across the VA that could be addressed with newly-engineered devices. Teams of Thayer students and faculty participating in a senior design course evaluate and engineer a solution for one of the problems. Exemplar projects have targeted …
Quantitative Cherenkov Emission Spectroscopy For Tissue Oxygenation Assessment, Johan Axelsson, Adam K. Glaser, David J. Gladstone, Brian W. Pogue
Quantitative Cherenkov Emission Spectroscopy For Tissue Oxygenation Assessment, Johan Axelsson, Adam K. Glaser, David J. Gladstone, Brian W. Pogue
Dartmouth Scholarship
Measurements of Cherenkov emission in tissue during radiation therapy are shown to enable estimation of hemoglobin oxygen saturation non-invasively, through spectral fitting of the spontaneous emissions from the treated tissue. Tissue oxygenation plays a critical role in the efficacy of radiation therapy to kill tumor tissue. Yet in-vivo measurement of this has remained elusive in routine use because of the complexity of oxygen measurement techniques. There is a spectrally broad emission of Cherenkov light that is induced during the time of irradiation, and as this travels through tissue from the point of the radiation deposition, the tissue absorption and scatter …
Ecological Payback Time Of An Energy-Efficient Modular Building, Jeremy Faludi, Michael Lepech
Ecological Payback Time Of An Energy-Efficient Modular Building, Jeremy Faludi, Michael Lepech
Dartmouth Scholarship
Ecological payback time was calculated for demolishing an existing commercial building with average energy performance and replacing it with an energy-efficient, prefabricated building. A life-cycle assessment was performed for a 5,000 ft2 commercial building designed by Project Frog and prefabricated in San Francisco, California, and compared to the impacts of annual energy consumption and continued status quo operation of a comparable average commercial building. Scenarios were run both with and without rooftop solar panels intended to make the prefabricated building net zero energy. The analysis considers the materials and mof the existing building, compared to continued annual energy use of …
Complete Genome Sequence Of Clostridium Clariflavum Dsm 19732, Javier A. Izquierdo, Lynne Goodwin, Karen W. Davenport, Hazuki Teshima
Complete Genome Sequence Of Clostridium Clariflavum Dsm 19732, Javier A. Izquierdo, Lynne Goodwin, Karen W. Davenport, Hazuki Teshima
Dartmouth Scholarship
Clostridium clariflavum is a Cluster III Clostridium within the family Clostridiaceae isolated from thermophilic anaerobic sludge (Shiratori et al, 2009). This species is of interest because of its similarity to the model cellulolytic organism Clostridium thermocellum and for the ability of environmental isolates to break down cellulose and hemicellulose. Here we describe features of the 4,897,678 bp long genome and its annotation, consisting of 4,131 protein-coding and 98 RNA genes, for the type strain DSM 19732.