Physical Sciences and Mathematics Commons^™

Mechanistic Insights Into The Reaction Of Chlorination Of Tryptophan Catalyzed By Tryptophan 7-Halogenase., Tatyana Karabencheva-Christova, Juan Torras, Adrian J Mulholland, Alessio Lodola, Christo Christov

Michigan Tech Publications

Tryptophan 7-halogenase catalyzes chlorination of free tryptophan to 7-chlorotryptophan, which is the first step in the antibiotic pyrrolnitrin biosynthesis. Many biologically and pharmaceutically active natural products contain chlorine and thus, an understanding of the mechanism of its introduction into organic molecules is important. Whilst enzyme-catalyzed chlorination is accomplished with ease, it remains a difficult task for the chemists. Therefore, utilizing enzymes in the synthesis of chlorinated organic compounds is important, and providing atomistic mechanistic insights about the reaction mechanism of tryptophan 7-halogenase is vital and timely. In this work, we examined a mechanism for the reaction of tryptophan chlorination, performed …

Cloudsat-Based Assessment Of Gpm Microwave Imager Snowfall Observation Capabilities, Giulia Panegrossi, Jean-François Rysman, Daniele Casella, Anna Cinzia Marra, Mark Kulie

Department of Geological and Mining Engineering and Sciences Publications

The sensitivity of Global Precipitation Measurement (GPM) Microwave Imager (GMI) high-frequency channels to snowfall at higher latitudes (around 60^◦N/S) is investigated using coincident CloudSat observations. The 166 GHz channel is highlighted throughout the study due to its ice scattering sensitivity and polarization information. The analysis of three case studies evidences the important combined role of total precipitable water (TPW), supercooled cloud water,and background surface composition on the brightness temperature (TB) behavior for different snow-producing clouds. A regression tree statistical analysis applied to the entire GMI-CloudSat snowfall dataset indicates which variables influence the 166 GHz polarization difference (166∆TB)and its …

Room Temperature Tunneling Switches And Methods Of Making And Using The Same, Yoke Khin Yap

Michigan Tech Patents

The tunneling channel of a field effect transistor comprising a plurality of tunneling elements contacting a channel substrate. Applying a source-drain voltage of greater than a turn-on voltage produces a source-drain current of greater than about 10 pA. Applying a source-drain voltage of less than a turn-on voltage produces a source-drain current of less than about 10 pA. The turn-on voltage at room temperature is between about 0.1V and about 40V.

Global Association Of Aerosol With Flash Density Of Intense Lightning, Orit Altaratz, Beata Kucienska, Alexander Kostinski, Graciela B. Raga, Ilan Koren

Department of Physics Publications

A global scale study of the association between aerosol loading and lightning production was conducted, using a full year’s data for 2012 (as well as seasonal data) of the cloud-to-ground lightning record from the world wide lightning location network and aerosol optical depth measured by MODIS. 70% of all grid squares examined and 94% of the statistically significant ones had higher flash densities under polluted conditions than the clean ones. This trend is evident for large continental regions in North, Central and South America, Europe, southern Africa and north-east Australia. A detailed examination of the link to the meteorology was …

Wearete: A Scalable Wearable E-Textile Triboelectric Energy Harvesting System For Human Motion Scavenging, Xian Li, Ye Sun

Michigan Tech Publications

In this paper, we report the design, experimental validation and application of a scalable, wearable e-textile triboelectric energy harvesting (WearETE) system for scavenging energy from activities of daily living. The WearETE system features ultra-low-cost material and manufacturing methods, high accessibility, and high feasibility for powering wearable sensors and electronics. The foam and e-textile are used as the two active tribomaterials for energy harvester design with the consideration of flexibility and wearability. A calibration platform is also developed to quantify the input mechanical power and power efficiency. The performance of the WearETE system for human motion scavenging is validated and calibrated …

Evolution Of Multispectral Aerosol Absorption Properties In A Biogenically-Influenced Urban Environment During The Cares Campaign, Madhu Gyawali, W. Patrick Arnott, Rahul A. Zaveri, Chen Song, Bradley Flowers, Manvendra K. Dubey, Swarup China, Claudio Mazzoleni, Kyle Gorkowski, Et Al.

Michigan Tech Publications

We present the evolution of multispectral optical properties through urban aerosols that have aged and interacted with biogenic emissions, resulting in stronger short wavelength absorption and the formation of moderately brown secondary organic aerosols. Ground-based aerosol measurements were made in June 2010 within the Sacramento urban area (site T0) and at a 40-km downwind location (site T1) in the forested Sierra Nevada foothills area. Data on black carbon (BC) and non-refractory aerosol mass and composition were collected at both sites. In addition, photoacoustic (PA) instruments with integrating nephelometers were used to measure spectral absorption and scattering coefficients for wavelengths ranging …

Satellite Observed Water Quality Changes In The Laurentian Great Lakes Due To Invasive Species, Anthropogenic Forcing, And Climate Change, Robert A. Shuchman, Karl Bosse, Michael J. Sayers, Gary L. Fahnenstiel, George Leshkevich

Michigan Tech Research Institute Publications

Long time series of ocean and land color satellite data can be used to measure Laurentian Great Lakes water quality parameters including chlorophyll, suspended minerals, harmful algal blooms (HABs), photic zone and primary productivity on weekly, monthly and annual observational intervals. The observed changes in these water quality parameters over time are a direct result of the introduction of invasive species such as the Dreissena mussels as well as anthropogenic forcing and climate change. Time series of the above mentioned water quality parameters have been generated based on a range of satellite sensors, starting with Landsat in the 1970s and …

All-Dielectric Metamaterials: Irrelevance Of Negative Refraction To Overlapped Mie Resonances, Navid Gandji, George Semouchkin, Elena Semouchkina

Michigan Tech Publications

All-dielectric metamaterials comprised of identical resonators draw a lot of attention as low-loss media providing for negative refraction, which is commonly attributed to the double negativity of effective material parameters caused by overlapping of Mie resonances. We study dispersion diagrams of such metamaterials composed of dielectric rod arrays and show that bandwidths of positive and negative refraction and its type are irrelevant to the negativity of effective parameters; instead, they are unambiguously defined by the shape and the location of the second transmission branch in dispersion diagrams and thus can be controlled by the lattice constants.

Computational Chemical Biology: From Atomistic Insights Towards Drug Design, Christo Christov

TechTalks

No abstract provided.

Deniable Encryption Storage For Mobile Devices, Bo Chen

TechTalks

I will introduce the progress of our work in building deniable storage systems for mobile devices. Generally, we rely on encryption to protect confidentiality of sensitive data. This conventional approach, however, is vulnerable to a coercive attack, in which the attacker may capture the device’s owner and coerce the owner to disclose the decryption key. We mitigate such a coercive attack by leveraging deniable encryption, to deny the existence of sensitive data even though the decryption key is compromised. This is extremely useful when a professional journalist or human rights worker collects criminal evidence using his/her mobile device in a …

Eureka! Discovering A New Mineral: Meralaniite, John A. Jaszczak

TechTalks

A series of serendipitous events and four years of collaborative research has led to the discovery and description of a new mineral- merelaniite. It is a natural nanocomposite composed primarily of MoS2 and PbS layers from the famous tanzanite gem mines in northern Tanzania. It's crystal structure and chemistry is unusual and complex, and forms unusual silvery, scroll-like whiskers. It was selected by the International Mineralogical Association as the 2016 Mineral of the Year.

Numerical Methods Of Miscible Displacements In Porous Media, Yang Yang

TechTalks

For miscible displacements in porous media, the volume fraction of the concentration is between 0 and 1. The main idea of my current work is to numerically preserve the two bound and keep the high-order accuracy. Then the numerical scheme is stable. The idea can be applied to other similar areas such as seawater intrusion, and contaminant transportation, etc.

Modelling Parallel Overhead From Simple Run-Time Records, Siegfried Höfinger, Ernst Haunschmid

Michigan Tech Publications

A number of scientific applications run on current HPC systems would benefit from an approximate assessment of parallel overhead. In many instances a quick and simple method to obtain a general overview on the subject is regarded useful auxiliary information by the routine HPC user. Here we present such a method using just execution times for increasing numbers of parallel processing cores. We start out with several common scientific applications and measure the fraction of time spent in MPI communication. Forming the ratio of MPI time to overall execution time we obtain a smooth curve that can be parameterized by …

Copper Isotope Constraints On The Genesis Of The Keweenaw Peninsula Native Copper District, Michigan, Usa, T. J. Bornhorst, Ryan Mathur

A. E. Seaman Mineral Museum Publications

The Keweenaw Peninsula native copper district of Michigan, USA is the largest concentration of native copper in the world. The copper isotopic composition of native copper was measured from stratabound and vein deposits, hosted by multiple rift-filling basalt-dominated stratigraphic horizons over 110 km of strike length. The δ⁶⁵Cu of the native copper has an overall mean of +0.28‰ and a range of −0.32‰ to +0.80‰ (excluding one anomalous value). The data appear to be normally distributed and unimodal with no substantial differences between the native copper isotopic composition from the wide spread of deposits studied here. This suggests …

Cross-Correlation-Based Structural System Identification Using Unmanned Aerial Vehicles., Hyungchul Yoon, Vedhus Hoskere, Jong-Woong Park, Billie F. Spencer

Michigan Tech Publications

Computer vision techniques have been employed to characterize dynamic properties of structures, as well as to capture structural motion for system identification purposes. All of these methods leverage image-processing techniques using a stationary camera. This requirement makes finding an effective location for camera installation difficult, because civil infrastructure (i.e., bridges, buildings, etc.) are often difficult to access, being constructed over rivers, roads, or other obstacles. This paper seeks to use video from Unmanned Aerial Vehicles (UAVs) to address this problem. As opposed to the traditional way of using stationary cameras, the use of UAVs brings the issue of the camera …

Robustness And Mode Selectivity In Parity-Time (Pt) Symmetric Lasers, M. H. Teimourpour, M. Khajavikhan, Demetrios N. Christodoulides, Ramy El-Ganainy

Department of Physics Publications

We investigate two important aspects of PT symmetric photonic molecule lasers, namely the robustness of their single longitudinal mode operation against instabilities triggered by spectral hole burning effects, and the possibility of more versatile mode selectivity. Our results, supported by numerically integrating the nonlinear rate equations and performing linear stability analysis, reveals the following: (1) In principle a second threshold exists after which single mode operation becomes unstable, signaling multimode oscillatory dynamics, (2) For a wide range of design parameters, single mode operation of PT lasers having relatively large free spectral range (FSR) can be robust even at higher gain …

Climate, Wildfire, And Erosion Ensemble Foretells More Sediment In Western Usa Watersheds, John B. Sankey, Jason Kreitler, Todd J. Hawbaker, Jason L. Mcvay, Mary Ellen Miller, Erich R. Mueller, Nicole M. Vaillant, Scott E. Lowe, Temuulen T. Sankey

Michigan Tech Research Institute Publications

The area burned annually by wildfires is expected to increase worldwide due to climate change. Burned areas increase soil erosion rates within watersheds, which can increase sedimentation in downstream rivers and reservoirs. However, which watersheds will be impacted by future wildfires is largely unknown. Using an ensemble of climate, fire, and erosion models, we show that postfire sedimentation is projected to increase for nearly nine tenths of watersheds by >10% and for more than one third of watersheds by >100% by the 2041 to 2050 decade in the western USA. The projected increases are statistically significant for more than eight …

Reference Data Set Of Volcanic Ash Physicochemical And Optical Properties, A. Vogel, S. Diplas, A. J. Durant, A. S. Azar, M. F. Sunding, William I. Rose, A. Sytchkova, C. Bonadonna, K. Krüger, A. Stohl

Department of Geological and Mining Engineering and Sciences Publications

Uncertainty in the physicochemical and optical properties of volcanic ash particles creates errors in the detection and modeling of volcanic ash clouds and in quantification of their potential impacts. In this study, we provide a data set that describes the physicochemical and optical properties of a representative selection of volcanic ash samples from nine different volcanic eruptions covering a wide range of silica contents (50–80 wt % SiO₂). We measured and calculated parameters describing the physical (size distribution, complex shape, and dense-rock equivalent mass density), chemical (bulk and surface composition), and optical (complex refractive index from ultraviolet to …

Effect Of Thermodenuding On The Structure Of Nascent Flame Soot Aggregates, Janarjan Bhandari, Swarup China, Timothy Onasch, Lindsay Wolff, Andrew Lambe, Paul Davidovits, Claudio Mazzoleni, Et Al.

Michigan Tech Publications

The optical properties (absorption and scattering) of soot particles depend on soot size and index of refraction, but also on the soot complex morphology and the internal mixing with materials that can condense on a freshly emitted (nascent) soot particle and coat it. This coating can affect the soot optical properties by refracting light, or by changing the soot aggregate structure. A common approach to studying the effect of coating on soot optical properties is to measure the absorption and scattering coefficients in ambient air, and then measure them again after removing the coating using a thermodenuder. In this approach, …

Enrollment Decision-Making In U.S. Forestry And Related Natural Resource Degree Programs, Mark Rouleau, Terry Sharik, Samantha Whitens, Adam Wellstead

Michigan Tech Publications

This article investigates enrollment decision-making trends among students currently enrolled in forestry and related natural resource (FRNR) degree programs in the United States. We conducted an online survey administered to all student participants attending the Society of American Foresters (SAF) National Convention in Salt Lake City, UT, in 2014 to obtain our enrollment decision-making data. Students were asked to rank the enrollment factors they considered most important to their decision to enroll, and factors that caused them to hesitate when enrolling in their degree program. We found that the “typical” FRNR enrollee was a person who enjoyed being outdoors and …

Cloud Droplets To Drizzle: Contribution Of Transition Drops To Microphysical And Optical Properties Of Marine Stratocumulus Clouds, S Glienke, A. Kostinski, J P. Fugal, R. A. Shaw, S Borrmann, J Stith

Department of Physics Publications

Aircraft measurements of the ubiquitous marine stratocumulus cloud type, with over 3000 km of in situ data from the Pacific during the Cloud System Evolution in the Trades experiment, show the ability of the Holographic Detector for Clouds (HOLODEC) instrument to smoothly interpolate the small and large droplet data collected with Cloud Droplet Probe and 2DC instruments. The combined, comprehensive instrument suite reveals a surprisingly large contribution in the predrizzle size range of 40–80 μm (transition droplets, or drizzlets), a range typically not measured and assumed to reside in a condensation‐to‐collision minimum between cloud droplet and drizzle modes. Besides shedding …

Effect Of Label Noise On The Machine-Learned Classification Of Earthquake Damage, Jared Frank, Umaa Rebbapragada, James Bialas, Thomas Oommen, Timothy C. Havens

Michigan Tech Publications

Automated classification of earthquake damage in remotely-sensed imagery using machine learning techniques depends on training data, or data examples that are labeled correctly by a human expert as containing damage or not. Mislabeled training data are a major source of classifier error due to the use of imprecise digital labeling tools and crowdsourced volunteers who are not adequately trained on or invested in the task. The spatial nature of remote sensing classification leads to the consistent mislabeling of classes that occur in close proximity to rubble, which is a major byproduct of earthquake damage in urban areas. In this study, …

Two-Dimensional Electronics And Optoelectronics: Present And Future, Zhixian Zhou, Yoke Khin Yap

Department of Physics Publications

Since the successful isolation of graphene a little over a decade ago, a wide variety of two-dimensional (2D) layered materials have been studied. They cover a broad spectrum of electronic properties, including metals, semimetals, semiconductors, and insulators. Many of these 2D materials have demonstrated promising potential for electronic and optoelectronic applications.

Non-Hermitian Matter-Wave Mixing In Bose-Einstein Condensates: Dissipation-Induced Amplification, S. Wuster, Ramy El-Ganainy

Department of Physics Publications

We investigate the nonlinear scattering dynamics in interacting atomic Bose-Einstein condensates under non-Hermitian dissipative conditions. We show that, by carefully engineering a momentum-dependent atomic loss profile, one can achieve matter-wave amplification through four-wave mixing in a quasi-one-dimensional nearly-free-space setup—a process that is forbidden in the counterpart Hermitian systems due to energy mismatch. Additionally, we show that similar effects lead to rich nonlinear dynamics in higher dimensions. Finally, we propose a physical realization for selectively tailoring the momentum-dependent atomic dissipation. Our strategy is based on a two-step process: (i) exciting atoms to narrow Rydberg or metastable excited states, and (ii) introducing …

Harmonic Distortion Minimization In Power Grids With Wind And Electric Vehicles, Ritam Misra, Sumit Paudyal, Oguzhan Ceylan, Paras Mandal

Michigan Tech Publications

Power-electronic interfacing based devices such as wind generators (WGs) and electrical vehicles (EVs) cause harmonic distortions on the power grid. Higher penetration and uncoordinated operation of WGs and EVs can lead to voltage and current harmonic distortions, which may exceed IEEE limits. It is interesting to note that WGs and EVs have some common harmonic profiles. Therefore, when EVs are connected to the grid, the harmonic pollution EVs impart onto the grid can be reduced to some extent by the amount of wind power injecting into the grid and vice versa. In this context, this work studies the impact of …

Recent Advances In Electronic And Optoelectronic Devices Based On Two-Dimensional Transition Metal Dichalcogenides, Mingxiao Ye, Dongyan Zhang, Yoke Khin Yap

Department of Physics Publications

Two-dimensional transition metal dichalcogenides (2D TMDCs) offer several attractive features for use in next-generation electronic and optoelectronic devices. Device applications of TMDCs have gained much research interest, and significant advancement has been recorded. In this review, the overall research advancement in electronic and optoelectronic devices based on TMDCs are summarized and discussed. In particular, we focus on evaluating field effect transistors (FETs), photovoltaic cells, light-emitting diodes (LEDs), photodetectors, lasers, and integrated circuits (ICs) using TMDCs.

Terrestrial Glint Seen From Deep Space: Oriented Ice Crystals Detected From The Lagrangian Point, Alexander Marshak, Tamas Varnai, Alexander Kostinski

Department of Physics Publications

The Deep Space Climate Observatory (DSCOVR) spacecraft resides at the first Lagrangian point about one million miles from Earth. A polychromatic imaging camera onboard delivers nearly hourly observations of the entire sunlit face of the Earth. Many images contain unexpected bright flashes of light over both ocean and land. We construct a yearlong time series of flash latitudes, scattering angles, and oxygen absorption to demonstrate conclusively that the flashes over land are specular reflections off tiny ice platelets floating in the air nearly horizontally. Such deep space detection of tropospheric ice can be used to constrain the likelihood of oriented …

Fluorescent Conjugated Polymers With A Bodipy-Based Backbone And Uses Thereof, Haiying Liu

Michigan Tech Patents

The present invention provides various fluorescent conjugated polymers with a BODIPY-based backbone. The invention also provides methods of using the polymers of the invention, such as for imaging and detection of cells, tumors, bacteria and viruses.

Topological Tight-Binding Models From Nontrivial Square Roots, J. Arkinstall, M. H. Teimourpour, L. Feng, Ramy El-Ganainy, H. Schomerus

Department of Physics Publications

We describe a versatile mechanism that provides tight-binding models with an enriched, topologically nontrivial band structure. The mechanism is algebraic in nature, and leads to tight-binding models that can be interpreted as a nontrivial square root of a parent lattice Hamiltonian—in analogy to the passage from a Klein-Gordon equation to a Dirac equation. In the tight-binding setting, the square-root operation admits to induce spectral symmetries at the expense of broken crystal symmetries. As we illustrate in detail for a simple one-dimensional example, the emergent and inherited spectral symmetries equip the energy gaps with independent topological quantum numbers that control the …

Volcanology - Multidisciplinary Science For A Versatile Campus, Simon Carn

Distinguished Lecture Series

Dr. Simon Carn was nominated by Dr. John Gierke and selected from a highly competitive pool of candidates as the Spring 2017 Distinguished Lecturer. His lecture, Volcanology — Multidisciplinary Science for a Versatile Campus, was presented in April 2017.

Volcanology – the study of volcanoes – is a truly multidisciplinary endeavor that encompasses numerous fields including geology, physics, chemistry, material science and social science. Arguably, Michigan Tech owes its very existence to volcanic activity, which is ultimately responsible for the area’s rich copper deposits and the development of mining in the Keweenaw.