Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons™

Open Access. Powered by Scholars. Published by Universities.®

2019

Publications and Research

Articles 1 - 30 of 81

Full-Text Articles in Physical Sciences and Mathematics

Dark-Binding Process Relevant To Preventing Photosensitized Oxidation: Conformation-Dependent Light And Dark Mechanisms By A Dual-Functioning Diketone, Sarah J. Belh, Niluksha Walalawela, Stas Lekhtman, Alexander Greer Dec 2019

Dark-Binding Process Relevant To Preventing Photosensitized Oxidation: Conformation-Dependent Light And Dark Mechanisms By A Dual-Functioning Diketone, Sarah J. Belh, Niluksha Walalawela, Stas Lekhtman, Alexander Greer

Publications and Research

Few photosensitizers function in both light and dark processes as they usually have no function when the lights are turned off. We hypothesized that light and dark mechanisms in an α-diketone will be decoupled by dihedral rotation in a conformation- dependent binding process. Successful decoupling of these two functions is now shown. Namely, anti- and syn-skewed conformations of 4,4′-dimethylbenzil promote photosensitized alkoxy radical production, whereas the syn conformation promotes a binding shutoff reaction with trimethyl phosphite. Less rotation of the diketone is better suited to the photosensitizing function since phosphite binding arises through the syn conformer of lower stability. The …

Go to article

Building Mof Nanocomposites With Oxidized Graphitic Carbon Nitride Nanospheres: The Effect Of Framework Geometry On The Structural Heterogeneity, Dimitrios A. Giannakoudakis, Teresa J. Bandosz Dec 2019

Building Mof Nanocomposites With Oxidized Graphitic Carbon Nitride Nanospheres: The Effect Of Framework Geometry On The Structural Heterogeneity, Dimitrios A. Giannakoudakis, Teresa J. Bandosz

Publications and Research

Composite of two MOFs, copper-based Cu-BTC (HKUST-1) and zirconium-based Zr-BDC (UiO-66), with oxidized graphitic carbon nitride nanospheres were synthesized. For comparison, pure MOFs were also obtained. The surface features were analyzed using x-ray diffraction (XRD), sorption of nitrogen, thermal analysis, and scanning electron microscopy (SEM). The incorporation of oxidized g-C3N4 to the Cu-BTC framework caused the formation of a heterogeneous material of a hierarchical pores structure, but a decreased surface area when compared to that of the parent MOF. In the case of UiO-66, functionalized nanospheres were acting as seeds around which the crystals grew. Even though the MOF phases …

Go to article

Determinism Of Stochastic Processes Through The Relationship Between The Heat Equation And Random Walks, Gurmehar Singh Makker Dec 2019

Determinism Of Stochastic Processes Through The Relationship Between The Heat Equation And Random Walks, Gurmehar Singh Makker

Publications and Research

We study the deterministic characteristics of stochastic processes through investigation of random walks and the heat equation. The relationship is confirmed by discretizing the heat equation in time and space and determining the probability distribution function for random walks in dimension d = 1, 2. The existence of the relationship is presented both through theoretical analysis and numerical computation.

Go to article

The Privacy Preserving Framework With Virtual Ring And Identity-Based Cryptography For Smart Grid, Leonard Sutanto Dec 2019

The Privacy Preserving Framework With Virtual Ring And Identity-Based Cryptography For Smart Grid, Leonard Sutanto

Publications and Research

One of the main challenges in the smart grid is how to efficiently manage the high-volume data from smart meters and sensors and preserve the privacy from the consumption data to avoid potential attacks (e.g., identity theft) for the involved prosumers, retail electricity providers and other clusters of distributed energy resources. This poster proposes a two-layer framework with the cloud computing infrastructure. The virtual ring and identity-based cryptography are utilized in each layer to preserve privacy efficiently. The methods of the virtual ring and identity-based cryptography are introduced. The purposes and needs are discussed at the end of this poster.

Go to article

An Application Of The Ising Model, Juliano A. Everett Dec 2019

An Application Of The Ising Model, Juliano A. Everett

Publications and Research

Understanding how the Ising model works,what it represents, and how it can be applied to neurology. Given that an Ising model is an Entropy model that could be representative of the firing of neurons, some assumptions of the system are made and then the process is simulated through Monte Carlo methods.

Go to article

Static Solid Relaxation Ordered Spectroscopy: Ss-Rosy, Gregory S. Boutis, Ravinath Kausik Nov 2019

Static Solid Relaxation Ordered Spectroscopy: Ss-Rosy, Gregory S. Boutis, Ravinath Kausik

Publications and Research

A two-dimensional pulse sequence is introduced for correlating nuclear magnetic resonance anisotropic chemical shifts to a relaxation time (e.g., T1) in solids under static conditions. The sequence begins with a preparatory stage for measuring relaxation times, and is followed by a multiple pulse sequence for homonuclear dipolar decoupling. Data analysis involves the use of Fourier transform, followed by a one-dimensional inverse Laplace transform for each frequency index. Experimental results acquired on solid samples demonstrate the general approach, and additional variations involving heteronuclear decoupling and magic angle spinning are discussed.

Go to article

Graded Quivers, Generalized Dimer Models And Toric Geometry, Sebastián Franco, Azeem Hasan Nov 2019

Graded Quivers, Generalized Dimer Models And Toric Geometry, Sebastián Franco, Azeem Hasan

Publications and Research

The open string sector of the topological B-model on CY (m+2)-folds is described by m-graded quivers with superpotentials. This correspondence extends to general m the well known connection between CY (m+2)-folds and gauge theories on the world-volume of D(5-2m)-branes for m = 0, ..., 3. We introduce m-dimers, which fully encode the m-graded quivers and their superpotentials, in the case in which the CY (m+2)-folds are toric. Generalizing the well known m = 1,2 cases, m-dimers significantly simplify the connection between geometry and m-graded quivers. A key …

Go to article

A Note On Graphs With Prescribed Orbit Structure, Abbe Mowshowitz, Matthias Dehmer, Frank Emmert-Streib Nov 2019

A Note On Graphs With Prescribed Orbit Structure, Abbe Mowshowitz, Matthias Dehmer, Frank Emmert-Streib

Publications and Research

No abstract provided.

Go to article

Residential Household Yard Care Practices Along Urban-Exurban Gradients In Six Climatically-Diverse U.S. Metropolitan Areas, Dexter H. Locke, Colin Polsky, J. Morgan Grove, Peter M. Groffman, Kristen C. Nelson, Kelli L. Larson, Jeannine Cavender-Bares, James B. Heffernan, Rinku Roy Chowdhury, Sarah E. Hobbie, Neil D. Bettez, Sharon J. Hall, Christopher Neill, Laura Ogden, Jarlath O'Neil-Dunne Nov 2019

Residential Household Yard Care Practices Along Urban-Exurban Gradients In Six Climatically-Diverse U.S. Metropolitan Areas, Dexter H. Locke, Colin Polsky, J. Morgan Grove, Peter M. Groffman, Kristen C. Nelson, Kelli L. Larson, Jeannine Cavender-Bares, James B. Heffernan, Rinku Roy Chowdhury, Sarah E. Hobbie, Neil D. Bettez, Sharon J. Hall, Christopher Neill, Laura Ogden, Jarlath O'Neil-Dunne

Publications and Research

Residential land is expanding in the United States, and lawn now covers more area than the country’s leading irrigated crop by area. Given that lawns are widespread across diverse climatic regions and there is rising concern about the environmental impacts associated with their management, there is a clear need to understand the geographic variation, drivers, and outcomes of common yard care practices. We hypothesized that 1) income, age, and the number of neighbors known by name will be positively associated with the odds of having irrigated, fertilized, or applied pesticides in the last year, 2) irrigation, fertilization, and pesticide application …

Go to article

Land Surface Temperature Variability Across India: A Remote Sensing Satellite Perspective, Satya Prakash, Hamidreza Norouzi Nov 2019

Land Surface Temperature Variability Across India: A Remote Sensing Satellite Perspective, Satya Prakash, Hamidreza Norouzi

Publications and Research

Land surface temperature (LST) plays a key role in the surface energy budget computation and land surface process studies. The Moderate Resolution Imaging Spectroradiometer (MODIS) sensors onboard the Aqua and Terra satellites provide comprehensive global LST estimates at a fine spatial resolution. The MODIS products were recently upgraded to Collection 6, and shown to be more accurate than its predecessor Collection 5 products. In this study, LST and its variability have been examined across India from Collection 6 of the Aqua MODIS data at 0.05° spatial resolution for the period of 2003 to 2017. All-India mean LST characteristics show distinctive …

Go to article

Planck's And Callendar's Blackbody Radiation Formulas And Their Fitness To Experimental Data, Max Tran Nov 2019

Planck's And Callendar's Blackbody Radiation Formulas And Their Fitness To Experimental Data, Max Tran

Publications and Research

In this paper, we compare the blackbody radiation density formula obtained with classical physics by Hugh L Callendar and the formula obtained by Max Planck using quantization of energy. We use R and Maxima to analyze their fitness on coordinating experimental data and indicate some limitations with experiments in this area.

Go to article

From The Human To The Planetary: Speculative Futures Of Care, Miriam Ticktin Oct 2019

From The Human To The Planetary: Speculative Futures Of Care, Miriam Ticktin

Publications and Research

This is largely a theoretical, speculative essay that takes on the question of what ‘care’ looks like at a moment when climate change is increasingly taking center stage in public and political discussions. Starting with two new practices, namely, humanitarian care for nonhumans and One Health collaborations, I seek to determine what forms of political care can incorporate the well-being of future generations and future iterations of the earth. After an exploration of One Health as an approach to planetary care, I ask what its parts enable us to think, despite its limitations; I focus on the new human-nonhuman assemblages …

Go to article

Evaluation Of Approaches For Mapping Tidal Wetlands Of The Chesapeake And Delaware Bays, Brian T. Lamb, Maria A. Tzortziou, Kyle C. Mcdonald Oct 2019

Evaluation Of Approaches For Mapping Tidal Wetlands Of The Chesapeake And Delaware Bays, Brian T. Lamb, Maria A. Tzortziou, Kyle C. Mcdonald

Publications and Research

The spatial extent and vegetation characteristics of tidal wetlands and their change are among the biggest unknowns and largest sources of uncertainty in modeling ecosystem processes and services at the land-ocean interface. Using a combination of moderate-high spatial resolution (

Go to article

Tio2/S-Doped Carbons Hybrids: Analysis Of Their Interfacial And Surface Features, Teresa Bandosz, Alfonso Policicchio, Marc Florent, Po S. Poon, Juan Matos Oct 2019

Tio2/S-Doped Carbons Hybrids: Analysis Of Their Interfacial And Surface Features, Teresa Bandosz, Alfonso Policicchio, Marc Florent, Po S. Poon, Juan Matos

Publications and Research

Hybrids containing approximately equal amounts of P25 TiO2 and S-doped porous carbons were prepared using a water-based slurry mixing method. The materials were extensively characterized by adsorption of nitrogen, potentiometric titration, thermal analysis in air and in helium, XRD, XPS and SEM. The collected results showed the significant blockage of carbon micropores by TiO2 particles deposited on their outer surface. The formation of a new interface, especially for the S-rich samples, might also contribute to the porosity alteration. Analysis of surface chemistry suggested the presence of Ti-S bonds with an involvement of sulfur from thiophenic species in the carbon phase. …

Go to article

An Engineering Geological Anatomy Of The Padma River Bank Failure And Erosion, 2018: A Case Study Of Naria Bank Section, Bangladesh, Mir Fazlul Karim, Nazrul I. Khandaker, Shahidul Haque, M. Zillur Rahman, Muhammad Qumrul Hassan, Asm Maksud Kamal, Masud Ahmed, Belal A. Sayeed Sep 2019

An Engineering Geological Anatomy Of The Padma River Bank Failure And Erosion, 2018: A Case Study Of Naria Bank Section, Bangladesh, Mir Fazlul Karim, Nazrul I. Khandaker, Shahidul Haque, M. Zillur Rahman, Muhammad Qumrul Hassan, Asm Maksud Kamal, Masud Ahmed, Belal A. Sayeed

Publications and Research

The Naria town of Bangladesh is developed on the right bank of the Padma River. The bank is an old natural levee of Meghna River. The Holocene-Recent geology of Naria is actively dominated by the fluvial processes of Ganges-Brahmaputra-Meghna River system where the deltaic sediments are characterized as unconsolidated fine sand and silt, covered by thin veneer of clayey silt and loam. The annual volume of water discharge and flow dynamics are dependent on the intensity of the rainfall, runoff and the length of dry winter. Excessive river bank erosion, channel avulsion, renewed submergence of floodplains, and formation of natural …

Go to article

Utilizing Dplot, Sedlog, And Arcgis Pro To Enhance Geologic Field Skills: Rosendale, Ulster County New York, Malek Shami, Nazrul I. Khandaker, Stanley Schleifer, Zarine Ali, Leonardo Sanchez, Gugu Ginindza, Tyn Tyn Nai Sep 2019

Utilizing Dplot, Sedlog, And Arcgis Pro To Enhance Geologic Field Skills: Rosendale, Ulster County New York, Malek Shami, Nazrul I. Khandaker, Stanley Schleifer, Zarine Ali, Leonardo Sanchez, Gugu Ginindza, Tyn Tyn Nai

Publications and Research

Capstone geologic field mapping courses in undergraduate geoscience programs aim to compliment the academic knowledge with technical field skills. As a pilot study, these tools were used to collect field data using folded lower Paleozoic to mid-Paleozoic sedimentary outcrops consisting of clastic, non-clastic and occasional mixed siliciclastics in Rosendale, Ulster County, New York. Rosendale is known for its classic geological outcrops with variable structural, stratigraphic, paleontological and sedimentological complexities – ideal for a field mapping course. Traditionally, students’ data acquisition in the field and its subsequent laboratory analysis to produce a final geologic field report utilized acetate overlays to produce …

Go to article

Paleoenvironment Of The Devonian Fossiliferous Glenerie Limestone, Rosendale, Upstate New York, Gugu Ginindza, B'Jorn K. Forde, Sebastian R. Agustin, Nazrul I. Khandaker, Malek Shami, Stanley Schleifer Sep 2019

Paleoenvironment Of The Devonian Fossiliferous Glenerie Limestone, Rosendale, Upstate New York, Gugu Ginindza, B'Jorn K. Forde, Sebastian R. Agustin, Nazrul I. Khandaker, Malek Shami, Stanley Schleifer

Publications and Research

The Devonian Glenerie limestone outcrops throughout the Hudson Valley and is believed to correlate with the glauconite-rich Oriskany sandstone elsewhere in upstate New York. Field inspection of well-preserved outcrops in Rosendale, upstate New York, indicated the Glenerie formation to be composed of both thin and thickly-bedded chert, interbedded shale, and both calcareous to arenaceous limestone. The Glenerie formation is dominated by spirifer arenosis fossil, which is the index fossil for this formation. The goal of this research is to determine the conditions of the paleoenvironment prevalent to the deposition of the Glenerie formation. Within the arenaceous layers are the spirifer …

Go to article

Positive Outcomes Of Involving Undergraduate And High School Students In Broader Aspect Of Earth System Science Through Peer Mentoring And Research Activities, Nazrul I. Khandaker, Shuayb Siddique, Matthew Khargie, Juanpablo Rodriguez, Adacia Teemal, Krishna Mahabir, Michael Robinson, Ality Aghedo, Zachary A. Sanichar, Sol De Leon, Tamzid Mubin, Elton Selby Sep 2019

Positive Outcomes Of Involving Undergraduate And High School Students In Broader Aspect Of Earth System Science Through Peer Mentoring And Research Activities, Nazrul I. Khandaker, Shuayb Siddique, Matthew Khargie, Juanpablo Rodriguez, Adacia Teemal, Krishna Mahabir, Michael Robinson, Ality Aghedo, Zachary A. Sanichar, Sol De Leon, Tamzid Mubin, Elton Selby

Publications and Research

The importance of involving undergraduates and high school students in field-and-laboratory research investigations at an early stage through peer mentoring has been clearly demonstrated as a critical tool for essential training to fully comprehend academic content and a deeper understanding of the various STEM, geoscience-and- environmental science related topics. As far as we are concerned, student presenters/participants (over 1000) in our topical sessions since 2004 have always found face-to-face presentation through poster sessions to be an ideal scientific venue where exchange of knowledge and discussion are fruitful, constructive and encouraging. It is quite revealing to note that among the student …

Go to article

Using Water Quality Index To Assess Groundwater Suitability At Gazipur District, Bangladesh, Muhammad Qumrul Hassan, Jowaher Raza, Mir F. Karim, Nazrul I. Khandaker Sep 2019

Using Water Quality Index To Assess Groundwater Suitability At Gazipur District, Bangladesh, Muhammad Qumrul Hassan, Jowaher Raza, Mir F. Karim, Nazrul I. Khandaker

Publications and Research

This study targeted to the suitability of groundwater for drinking purpose at Gazipur District undergoing rapid urbanization and increasing industrialization. The District has an area of 1741.53 km2, located in between 23°53' and 24°21' north latitudes and in between 90°09' and 92°39' east longitudes. From six Upazilas in Gazipur District, a total of 130 groundwater samples were collected, which are, Gazipur Sadar Upazila, Sreepur Upazila, Kaliakoir Upazila, Kapasia Upazila, and Kaligonj Upazila. A recent field observation review of industrial sludge found that heavy metal concentration was above the acceptable limit for agricultural soil. Gazipur being adjacent to Dhaka …

Go to article

Amazon Alexa + Linked Open Data: Theorizing Concerning Relationships Between (Surveillant) Smart-Home Voice Assistants And Linked Open Data, Michelle Nitto Sep 2019

Amazon Alexa + Linked Open Data: Theorizing Concerning Relationships Between (Surveillant) Smart-Home Voice Assistants And Linked Open Data, Michelle Nitto

Publications and Research

No abstract provided.

Go to article

Deep Machine Learning Techniques For The Detection And Classification Of Sperm Whale Bioacoustics, Peter C. Bermant, Michael M. Bronstein, Robert J. Wood, Shane Gero, David F. Gruber Aug 2019

Deep Machine Learning Techniques For The Detection And Classification Of Sperm Whale Bioacoustics, Peter C. Bermant, Michael M. Bronstein, Robert J. Wood, Shane Gero, David F. Gruber

Publications and Research

We implemented Machine Learning (ML) techniques to advance the study of sperm whale (Physeter macrocephalus) bioacoustics. This entailed employing Convolutional Neural Networks (CNNs) to construct an echolocation click detector designed to classify spectrograms generated from sperm whale acoustic data according to the presence or absence of a click. The click detector achieved 99.5% accuracy in classifying 650 spectrograms. The successful application of CNNs to clicks reveals the potential of future studies to train CNN-based architectures to extract finer-scale details from cetacean spectrograms. Long short-term memory and gated recurrent unit recurrent neural networks were trained to perform classification tasks, including (1) …

Go to article

Going Big: A Large-Scale Study On What Big Data Developers Ask, Mehdi Bagherzadeh, Raffi T. Khatchadourian Aug 2019

Going Big: A Large-Scale Study On What Big Data Developers Ask, Mehdi Bagherzadeh, Raffi T. Khatchadourian

Publications and Research

Software developers are increasingly required to write big data code. However, they find big data software development challenging. To help these developers it is necessary to understand big data topics that they are interested in and the difficulty of finding answers for questions in these topics. In this work, we conduct a large-scale study on Stackoverflow to understand the interest and difficulties of big data developers. To conduct the study, we develop a set of big data tags to extract big data posts from Stackoverflow; use topic modeling to group these posts into big data topics; group similar topics into …

Go to article

Yields Of Weakly Bound Light Nuclei As A Probe Of The Statistical Hadronization Model, Yiming Cai, Thomas D. Cohen, Boris A. Gelman, Yukari Yamauchi Aug 2019

Yields Of Weakly Bound Light Nuclei As A Probe Of The Statistical Hadronization Model, Yiming Cai, Thomas D. Cohen, Boris A. Gelman, Yukari Yamauchi

Publications and Research

The statistical hadronization model successfully describes the yields of hadrons and light nuclei from central heavy-ion collisions over a wide range of energies. It is a simple and efficient phenomenological framework in which the relative yields for very high energy collisions are essentially determined by a single model parameter—the chemical freeze-out temperature. Recent measurements of yields of hadrons and light nuclei covering over nine orders of magnitudes from the ALICE collaboration at the Large Hadron Collider were described by the model with remarkable accuracy with a chemical freeze-out temperature of 156.5 ± 1.5 MeV. A key physical question is whether …

Go to article

Hidden Bias In The Dud-E Dataset Leads To Misleading Performance Of Deep Learning In Structure-Based Virtual Screening, Lieyang Chen, Anthony Cruz, Steven Ramsey, Callum J. Dickson, Jose S. Duca, Viktor Hornak, David R. Koes, Tom Kurtzman Aug 2019

Hidden Bias In The Dud-E Dataset Leads To Misleading Performance Of Deep Learning In Structure-Based Virtual Screening, Lieyang Chen, Anthony Cruz, Steven Ramsey, Callum J. Dickson, Jose S. Duca, Viktor Hornak, David R. Koes, Tom Kurtzman

Publications and Research

Recently much effort has been invested in using convolutional neural network (CNN) models trained on 3D structural images of protein-ligand complexes to distinguish binding from non-binding ligands for virtual screening. However, the dearth of reliable protein-ligand x-ray structures and binding affinity data has required the use of constructed datasets for the training and evaluation of CNN molecular recognition models. Here, we outline various sources of bias in one such widely-used dataset, the Directory of Useful Decoys: Enhanced (DUDE). We have constructed and performed tests to investigate whether CNN models developed using DUD-E are properly learning the underlying physics of molecular …

Go to article

Hidden Bias In The Dud-E Dataset Leads To Misleading Performance Of Deep Learning In Structure-Based Virtual Screening, Lieyang Chen, Anthony Cruz, Steven Ramsey, Callum J. Dickson, Jose S. Duca, Viktor Hornak, David R. Koes, Tom Kurtzman Aug 2019

Hidden Bias In The Dud-E Dataset Leads To Misleading Performance Of Deep Learning In Structure-Based Virtual Screening, Lieyang Chen, Anthony Cruz, Steven Ramsey, Callum J. Dickson, Jose S. Duca, Viktor Hornak, David R. Koes, Tom Kurtzman

Publications and Research

Recently much effort has been invested in using convolutional neural network (CNN) models trained on 3D structural images of protein-ligand complexes to distinguish binding from non-binding ligands for virtual screening. However, the dearth of reliable protein-ligand x-ray structures and binding affinity data has required the use of constructed datasets for the training and evaluation of CNN molecular recognition models. Here, we outline various sources of bias in one such widely-used dataset, the Directory of Useful Decoys: Enhanced (DUDE). We have constructed and performed tests to investigate whether CNN models developed using DUD-E are properly learning the underlying physics of molecular …

Go to article

A Note On Distance-Based Entropy Of Dendrimers, Modjtaba Ghorbani, Matthias Dehmer, Samaneh Zangi, Abbe Mowshowitz, Frank Emmert-Streib Aug 2019

A Note On Distance-Based Entropy Of Dendrimers, Modjtaba Ghorbani, Matthias Dehmer, Samaneh Zangi, Abbe Mowshowitz, Frank Emmert-Streib

Publications and Research

This paper introduces a variant of entropy measures based on vertex eccentricity and applies it to all graphs representing the isomers of octane. Taking into account the vertex degree as well (degree-ecc-entropy), we find a good correlation with the acentric factor of octane isomers. In particular, we compute the degree-ecc-entropy for three classes of dendrimer graphs.

Go to article

Master Integrals For The Two-Loop, Non-Planar Qcd Corrections To Top-Quark Pair Production In The Quark-Annihilation Channel, Matteo Becchetti, Roberto Bonciani, Valerio Casconi, Andrea Ferroglia, Simone Lavacca, Andreas Von Manteuffel Aug 2019

Master Integrals For The Two-Loop, Non-Planar Qcd Corrections To Top-Quark Pair Production In The Quark-Annihilation Channel, Matteo Becchetti, Roberto Bonciani, Valerio Casconi, Andrea Ferroglia, Simone Lavacca, Andreas Von Manteuffel

Publications and Research

We present the analytic calculation of the Master Integrals for the two-loop, non-planar topologies that enter the calculation of the amplitude for top-quark pair hadroproduction in the quark-annihilation channel. Using the method of differential equations, we expand the integrals in powers of the dimensional regulator ε and determine the expansion coefficients in terms of generalized harmonic polylogarithms of two dimensionless variables through to weight four.

Go to article

Synthesis And Evaluations Of “1,4-Triazolyl Combretacoumarins” And Desmethoxy Analogs, Tashrique A. Khandaker, Jessica D. Hess, Renato Aguilera, Graciela Andrei, Robert Snoeck, Dominique Schols, Padmanava Pradhan, Mahesh K. Lakshman Aug 2019

Synthesis And Evaluations Of “1,4-Triazolyl Combretacoumarins” And Desmethoxy Analogs, Tashrique A. Khandaker, Jessica D. Hess, Renato Aguilera, Graciela Andrei, Robert Snoeck, Dominique Schols, Padmanava Pradhan, Mahesh K. Lakshman

Publications and Research

1,4-Triazolyl combretacoumarins have been prepared by linking the trimethoxyarene unit of combretastatin A4 with coumarins, via a 1,2,3-triazole. For this, 4-azidocoumarins were accessed by a sequential two-step, one-pot reaction of 4-hydroxycoumarins with (benzotriazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate (BOP), followed by reaction with NaN3. In the reaction with BOP, a coumarin-derived phosphonium ion intermediate seems to form, leading to an O4-(benzotriazolyl)coumarin derivative. For the CuAAC reaction of azidocoumarins with 5-ethynyl-1,2,3-trimethoxybenzene, catalytic [(MeCN)4Cu]PF6 in CH2Cl2/MeOH with 2,6-lutidine, at 50 oC, was suitable. The 4-azidocoumarins were less reactive as compared to PhN3 and …

Go to article

An Optimized Encoding Algorithm For Systematic Polar Codes, Xiumin Wang, Zhihong Zhang, Jun Li, Yu Wang, Haiyan Cao, Zhengquan Li, Liang Shan Aug 2019

An Optimized Encoding Algorithm For Systematic Polar Codes, Xiumin Wang, Zhihong Zhang, Jun Li, Yu Wang, Haiyan Cao, Zhengquan Li, Liang Shan

Publications and Research

Many different encoding algorithms for systematic polar codes (SPC) have been introduced since SPC was proposed in 2011. However, the number of the computing units of exclusive OR (XOR) has not been optimized yet. According to an iterative property of the generator matrix and particular lower triangular structure of the matrix, we propose an optimized encoding algorithm (OEA) of SPC that can reduce the number of XOR computing units compared with existing non-recursive algorithms. We also prove that this property of the generator matrix could extend to different code lengths and rates of the polar codes. Through the matrix segmentation …

Go to article

Rocketry And Observability Predictions For Cubesat, Juliano A. Everett Aug 2019

Rocketry And Observability Predictions For Cubesat, Juliano A. Everett

Publications and Research

Estimating the visibility of Sunlight reflected by the holographic retro-reflector of Cubesat Alpha, and to convert this to star apparent magnitude to learn more about the visibility of these sails through reflected sunlight, to in turn determine if glints of these holograms are visible by terrestrial observers.

Go to article

Next Last