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Articles 149881 - 149910 of 294521

Full-Text Articles in Physical Sciences and Mathematics

Gambling Problems In The General Danish Population: Survey Evidence, Morten Lau, Don Ross Jun 2016

Gambling Problems In The General Danish Population: Survey Evidence, Morten Lau, Don Ross

International Conference on Gambling & Risk Taking

We develop surveys of gambling problems in the general Danish population. We compare several popular survey instruments of gambling behavior and gambling propensity to assess if they differ in their classification of individuals. We also examine correlations with standard survey instruments for alcohol use, anxiety, depression and impulsiveness. A feature of our design is that nobody was excluded on the basis of their response to a “trigger,” “gateway” or “diagnostic item” question about previous gambling history, allowing us to check for sample selection bias. Our sample consists of 8,405 adult Danes, which is 12.8% of the sample frame of 65,592 …


Generational Differences In Gambling Behavior And Attitudes, Don Feeney, Todd Maki Jun 2016

Generational Differences In Gambling Behavior And Attitudes, Don Feeney, Todd Maki

International Conference on Gambling & Risk Taking

The five generations that make up the adult population of North America and Europe differ greatly in their gambling behavior and their beliefs and attitudes towards gambling. This presentation will discuss data that demonstrate the extent of these differences as well as the cultural background and formative experiences that led to them. It will conclude with a discussion of implications for the gambling industry, responsible gambling, public policy, and for those concerned with the prevention and treatment of gambling problems.


Well I'Ll Be Damned - Insights Into Predictive Value Of Pedigree Information In Horse Racing, Timothy Baker Mr, Ming-Chien Sung, Johnnie Johnson Professor, Tiejun Ma Jun 2016

Well I'Ll Be Damned - Insights Into Predictive Value Of Pedigree Information In Horse Racing, Timothy Baker Mr, Ming-Chien Sung, Johnnie Johnson Professor, Tiejun Ma

International Conference on Gambling & Risk Taking

Fundamental form characteristics like how fast a horse ran at its last start, are widely used to help predict the outcome of horse racing events. The exception being in races where horses haven’t previously competed, such as Maiden races, where there is little or no publicly available past performance information. In these types of events bettors need only consider a simplified suite of factors however this is offset by a higher level of uncertainty. This paper examines the inherent information content embedded within a horse’s ancestry and the extent to which this information is discounted in the United Kingdom bookmaker …


Stationary And Time-Dependent Optimization Of The Casino Floor Slot Machine Mix, Anastasia D. Baran, Jason D. Fiege Jun 2016

Stationary And Time-Dependent Optimization Of The Casino Floor Slot Machine Mix, Anastasia D. Baran, Jason D. Fiege

International Conference on Gambling & Risk Taking

Modeling and optimizing the performance of a mix of slot machines on a gaming floor can be addressed at various levels of coarseness, and may or may not consider time-dependent trends. For example, a model might consider only time-averaged, aggregate data for all machines of a given type; time-dependent aggregate data; time-averaged data for individual machines; or fully time dependent data for individual machines. Fine-grained, time-dependent data for individual machines offers the most potential for detailed analysis and improvements to the casino floor performance, but also suffers the greatest amount of statistical noise. We present a theoretical analysis of single …


Psychiatric Comorbidities In Gambling And The Clubsnsw Chaplaincy Program (Australia), Melanie Hartmann, Alex Blaszczynski, Rowan Cameron Jun 2016

Psychiatric Comorbidities In Gambling And The Clubsnsw Chaplaincy Program (Australia), Melanie Hartmann, Alex Blaszczynski, Rowan Cameron

International Conference on Gambling & Risk Taking

A recent systematic review of population studies conducted over the last 12 years indicated that 57.5% of individuals meeting criteria for a gambling disorder have a comorbid substance use disorder, 60.1% a nicotine dependence, 57.5% a mood disorder, and 37.4%, any anxiety disorder. In a proportion of these, the comorbid condition predates the onset of gambling disorders suggesting these might represent a vulnerability factor. These findings suggest important implications for gambling prevention and treatments. Instead of promoting only gambling specific interventions and treatments, the emphasis needs to be on a more holistic approach that includes screening for and treating comorbid …


Privacy-Preserving Data Mining On Hospitality Big Data, Mandana Bozorgi, Yoohwan Kim Jun 2016

Privacy-Preserving Data Mining On Hospitality Big Data, Mandana Bozorgi, Yoohwan Kim

International Conference on Gambling & Risk Taking

In this paper we present a summary of our activity associated with the security and encryption the big data on the hotels big data. We give a brief introduction to some techniques for security the data set in large scale, we then look into the homomorphism and Map Reduce environment. With the advances in computer architecture and silicon technology, processing large data set becomes possible after some fundamental data storage and processing algorithm been proposed and implemented. Analyzing the big data opened many opportunities for scientists in different research and application areas. Hospitality industry, for example, collects and keeps customers …


Survival And Cause-Specific Mortality Of Female Eastern Wild Turkeys In Two Frequently-Burned Longleaf Pine Savannas, Andrew R. Little, John F. Benson, Michael J. Chamberlain, L. Mike Conner, Robert J. Warren Jun 2016

Survival And Cause-Specific Mortality Of Female Eastern Wild Turkeys In Two Frequently-Burned Longleaf Pine Savannas, Andrew R. Little, John F. Benson, Michael J. Chamberlain, L. Mike Conner, Robert J. Warren

School of Natural Resources: Faculty Publications

Longleaf pine savannas have declined throughout the southeastern United States due to land-use change. Fortunately, natural resource professionals are currently restoring these ecologically and economically important savannas. Although efforts are underway to restore longleaf pine savannas, little information exists on female eastern wild turkey Meleagris gallopavo silvestris population dynamics in these systems. Therefore, we evaluated survival and cause-specific mortality of female eastern wild turkeys in two longleaf pine savannas in southwestern Georgia. We radio-marked 126 female wild turkeys during 2010–2013 and monitored their survival; 66 (52.4%) radio-marked females died during the study. We estimated causes of death for 37 mortality …


Aggieair Published In Nature Conservancy Utah, Aggieair Jun 2016

Aggieair Published In Nature Conservancy Utah, Aggieair

News

AggieAir was contracted by Nature Conservancy to Fly Yellow Creek, a tributary of the Bear River.

AggieAir provided them with 35 river miles of RGB and thermal imagery in order to develop an ecological integrity map for Northern Leatherside chub habitat. Doing so provides the Nature Conservancy with high quality data that enables them to delineate/see areas of substandard, average, and excellent quality habitats and how to better manage those habitats.


Analytic Models Of Brown Dwarfs And The Substellar Mass Limit, Sree Ram Valluri, Shantanu Basu, Sayantan Auddy Jun 2016

Analytic Models Of Brown Dwarfs And The Substellar Mass Limit, Sree Ram Valluri, Shantanu Basu, Sayantan Auddy

Physics and Astronomy Publications

We present the analytic theory of brown dwarf evolution and the lower mass limit of the hydrogen burning main-sequence stars and introduce some modifications to the existing models. We give an exact expression for the pressure of an ideal nonrelativistic Fermi gas at a finite temperature, therefore allowing for nonzero values of the degeneracy parameter. We review the derivation of surface luminosity using an entropy matching condition and the first-order phase transition between the molecular hydrogen in the outer envelope and the partially ionized hydrogen in the inner region.We also discuss the results of modern simulations of the plasma phase …


Rotamer-Restricted Fluorogenicity Of The Bis-Arsenical Reash, A. S. Walker, Paul R. Rablen, A. Schepartz Jun 2016

Rotamer-Restricted Fluorogenicity Of The Bis-Arsenical Reash, A. S. Walker, Paul R. Rablen, A. Schepartz

Chemistry & Biochemistry Faculty Works

Fluorogenic dyes such as FlAsH and ReAsH are used widely to localize, monitor, and characterize proteins and their assemblies in live cells. These bis-arsenical dyes can become fluorescent when bound to a protein containing four proximal Cys thiols—a tetracysteine (Cys4) motif. Yet the mechanism by which bis-arsenicals become fluorescent upon binding a Cys4 motif is unknown, and this nescience limits more widespread application of this tool. Here we probe the origins of ReAsH fluorogenicity using both computation and experiment. Our results support a model in which ReAsH fluorescence depends on the relative orientation of the aryl chromophore and the appended …


Image Spam Analysis, Annapurna Sowmya Annadatha Jun 2016

Image Spam Analysis, Annapurna Sowmya Annadatha

Master's Projects

Image spam is unsolicited bulk email, where the message is embedded in an image. This technique is used to evade text-based spam lters. In this research, we analyze and compare two novel approaches for detecting spam images. Our rst approach focuses on the extraction of a broad set of image features and selection of an optimal subset using a Support Vector Machine (SVM). Our second approach is based on Principal Component Analysis (PCA), where we determine eigenvectors for a set of spam images and compute scores by projecting images onto the resulting eigenspace. Both approaches provide high accuracy with low …


Defeating N-Gram Scores For Http Attack Detection, Samyuktha Sridharan Jun 2016

Defeating N-Gram Scores For Http Attack Detection, Samyuktha Sridharan

Master's Projects

Web applications that generate malicious HTTP requests provide a platform that attackers use to exploit vulnerable machines. Such malicious traffic should be identified by network intrusion detection systems, based on traffic analysis. Previous research has shown that n-gram techniques can be successfully applied to detect HTTP attacks. In this research, we analyze the robustness of these n-gram techniques. We show that n-gram scores are surprisingly robust, but can be defeated using certain obfuscation strategies. We also consider the need for a more costlier HMM-based intrusion detection system.


Machine Learning On The Cloud For Pattern Recognition, Tien Nguyen Jun 2016

Machine Learning On The Cloud For Pattern Recognition, Tien Nguyen

Master's Projects

Pattern recognition is a field of machine learning with applications to areas such as text recognition and computer vision. Machine learning algorithms, such as convolutional neural networks, may be trained to classify images. However, such tasks may be computationally intensive for a commercial computer for larger volumes or larger sizes of images. Cloud computing allows one to overcome the processing and memory constraints of average commercial computers, allowing computations on larger amounts of data. In this project, we developed a system for detection and tracking of moving human and vehicle objects in videos in real time or near real time. …


How Did We Wind Up In Such An Unlikely Universe?, Michael Bass Jun 2016

How Did We Wind Up In Such An Unlikely Universe?, Michael Bass

UCF Forum

Not long ago the Public Broadcasting Service program NOVA presented an episode called “The Great Math Mystery.” It dealt with the many ways mathematical relationships and special numbers crop up when investigating the physical and natural world.


VigenèRe Score For Malware Detection, Suchita Deshmukh Jun 2016

VigenèRe Score For Malware Detection, Suchita Deshmukh

Master's Projects

Previous research has applied classic cryptanalytic techniques to the malware detection problem. Speci cally, scores based on simple substitution cipher cryptanal- ysis and various generalizations have been considered. In this research, we analyze two new malware scoring techniques based on classic cryptanalysis. Our rst ap- proach relies on the Index of Coincidence, which is used, for example, to determine the length of the keyword in a Vigenère ciphertext. We also consider a score based on a more complete cryptanalysis of a Vigenère cipher. We nd that the Vigenère score is competitive with previous statistical-based malware scores.


Alumni Narratives On Computational Geology (Spring 1997 – Fall 2013), Victor J. Ricchezza Jun 2016

Alumni Narratives On Computational Geology (Spring 1997 – Fall 2013), Victor J. Ricchezza

USF Tampa Graduate Theses and Dissertations

Recent meetings and publications have discussed what geoscience undergraduates should learn for professional success, and among other items, have identified several quantitative skills and habits of mind as being necessary for geoscience students; many of these items are commonly associated with Quantitative Literacy (QL). The Computational Geology course in the geology department has been evolving at USF for 20 years. The course teaches QL in a geologic setting independent of specific core geology topics. This course has long preceded the national acknowledgment of the need for what it teaches within the field. As the first of a series of related …


Static And Dynamic Analysis For Android Malware Detection, Ankita Kapratwar Jun 2016

Static And Dynamic Analysis For Android Malware Detection, Ankita Kapratwar

Master's Projects

Static analysis relies on features extracted without executing code, while dynamic analysis extracts features based on code execution (or emulation). In general, static analysis is more e cient, while static analysis is often more informative, particularly in cases of highly obfuscated code. Static analysis of an Android application can rely on features extracted from the manifest le or the Java bytecode, while dynamic analysis of Android applications can deal with features involving dynamic code loading and system calls that are collected while the application is running. In this research, we analyzed the e ectiveness of combining static and dynamic features …


Determining The Effectiveness Of Soil Treatment On Plant Stress Using Smart-Phone Cameras, Anurag Panwar Jun 2016

Determining The Effectiveness Of Soil Treatment On Plant Stress Using Smart-Phone Cameras, Anurag Panwar

USF Tampa Graduate Theses and Dissertations

Plants are vital to the health of our biosphere, and effectively sustaining their growth is fundamental to the existence of life on this planet. A critical aspect, which decides the sustainability of plant growth is the quality of soil. All other things being fixed, the quality of soil greatly impacts the plant stress, which in turn impacts overall health. Although plant stress manifests in many ways, one of the clearest indicators are colors of the leaves. In this thesis, we conducted an experimental study in a greenhouse for detecting plant stress caused by nutrient deficienceies in soil using smartphone cameras, …


Responsible Gaming Certification Standards, Dietmar Hoscher Jun 2016

Responsible Gaming Certification Standards, Dietmar Hoscher

International Conference on Gambling & Risk Taking

The European Casino Association (ECA) is representing the licensed European Casino industry in Brussels. It represents some 900 casinos form 24 European countires which employ around 70.000 staff.

In 2013 the ECA launched a project among its members concerning Responsible Gaming. A Working Group headed by Prof. Hoscher a Board Mamber of Casinos Austria AG was formed. The members where Resposnible Gaming Experts fom the different companies and associations within the ECA network.

The working group established a Responsible Gaming Framework that represents a collection of measures to presevent gambling addictions and identify vulonerable persons. The collection of measures are …


The Economics Of Lotto, Ian Walker, Robert E. Pryce, Rhys Wheeler, Nick Powdathvee Jun 2016

The Economics Of Lotto, Ian Walker, Robert E. Pryce, Rhys Wheeler, Nick Powdathvee

International Conference on Gambling & Risk Taking

No abstract provided.


Characterization Of Cumulus Cloud Fields Using Trajectories In The Center Of Gravity Versus Water Mass Phase Space: 2. Aerosol Effects On Warm Convective Clouds, Reuven H. Heiblum, Orit Altaratz, Ilan Koren, Graham Feingold, Alexander Kostinski, Alexander Khain, Mikhail S. Ovchinnikov, Guy Dagan, Lital Pinto, Ricki Yaish, Qian Chen Jun 2016

Characterization Of Cumulus Cloud Fields Using Trajectories In The Center Of Gravity Versus Water Mass Phase Space: 2. Aerosol Effects On Warm Convective Clouds, Reuven H. Heiblum, Orit Altaratz, Ilan Koren, Graham Feingold, Alexander Kostinski, Alexander Khain, Mikhail S. Ovchinnikov, Guy Dagan, Lital Pinto, Ricki Yaish, Qian Chen

Department of Physics Publications

In Part I of this work a 3‐D cloud tracking algorithm and phase space of center of gravity altitude versus cloud liquid water mass (CvM space) were introduced and described in detail. We showed how new physical insight can be gained by following cloud trajectories in the CvM space. Here this approach is used to investigate aerosol effects on cloud fields of warm cumuli. We show a clear effect of the aerosol loading on the shape and size of CvM clusters. We also find fundamental differences in the CvM space between simulations using bin versus bulk microphysical schemes, with the …


Characterization Of Cumulus Cloud Fields Using Trajectories In The Center Of Gravity Versus Water Mass Phase Space: 1. Cloud Tracking And Phase Space Description, Reuven H. Heiblum, Orit Altaratz, Ilan Koren, Graham Feingold, Alexander Kostinski, Alexander Khain, Mikhail S. Ovchinnikov, Erick Fredj, Lital Pinto, Ricki Yaish, Qian Chen Jun 2016

Characterization Of Cumulus Cloud Fields Using Trajectories In The Center Of Gravity Versus Water Mass Phase Space: 1. Cloud Tracking And Phase Space Description, Reuven H. Heiblum, Orit Altaratz, Ilan Koren, Graham Feingold, Alexander Kostinski, Alexander Khain, Mikhail S. Ovchinnikov, Erick Fredj, Lital Pinto, Ricki Yaish, Qian Chen

Department of Physics Publications

We study the evolution of warm convective cloud fields using large eddy simulations of continental and trade cumulus. Individual clouds are tracked a posteriori from formation to dissipation using a 3‐D cloud‐tracking algorithm, and results are presented in the phase space of center of gravity altitude versus cloud liquid water mass (CvM space). The CvM space is shown to contain rich information on cloud field characteristics, cloud morphology, and common cloud development pathways, together facilitating a comprehensive understanding of the cloud field. In this part we show how the meteorological (thermodynamic) conditions that determine the cloud properties are projected on …


U.S. Drought Monitor, June 7, 2016, Deborah J. Bathke Jun 2016

U.S. Drought Monitor, June 7, 2016, Deborah J. Bathke

United States Agricultural Commodities in Drought Archive

Drought map of U.S. for June 7, 2016 (6/7/16) plus: U.S. crop areas experiencing drought (map), Approximate percentage of crop located in drought, by state (bar graph), Percent of crop area located in drought, past 52 weeks (line graph) for: Corn, Soybeans, Hay, Cattle, Winter wheat.


Hst Imaging Of The Dusty Filaments And Nucleus Swirl In Ngc4696 At The Centre Of The Centaurus Cluster, A. C. Fabian, S. A. Walker, H. R. Russell, C. Pinto, R. E. A. Canning, P. Salome, J. S. Sanders, G. B. Taylor, E. G. Zweibel, C. J. Conselice, F. Combes, C. S. Crawford, Gary J. Ferland, J. S. Gallagher Iii, N. A. Hatch, R. M. Johnstone, C. S. Reynolds Jun 2016

Hst Imaging Of The Dusty Filaments And Nucleus Swirl In Ngc4696 At The Centre Of The Centaurus Cluster, A. C. Fabian, S. A. Walker, H. R. Russell, C. Pinto, R. E. A. Canning, P. Salome, J. S. Sanders, G. B. Taylor, E. G. Zweibel, C. J. Conselice, F. Combes, C. S. Crawford, Gary J. Ferland, J. S. Gallagher Iii, N. A. Hatch, R. M. Johnstone, C. S. Reynolds

Physics and Astronomy Faculty Publications

Narrow-band HST imaging has resolved the detailed internal structure of the 10 kpc diameter H α+[N II] emission line nebulosity in NGC4696, the central galaxy in the nearby Centaurus cluster, showing that the dusty, molecular, filaments have a width of about 60 pc. Optical morphology and velocity measurements indicate that the filaments are dragged out by the bubbling action of the radio source as part of the active galactic nucleus feedback cycle. Using the drag force we find that the magnetic field in the filaments is in approximate pressure equipartition with the hot gas. The filamentary nature of the …


Gw150914: First Results From The Search For Binary Black Hole Coalescence With Advanced Ligo, B. P. Abbott, R. Abbott, T. D. Abbott, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov Jun 2016

Gw150914: First Results From The Search For Binary Black Hole Coalescence With Advanced Ligo, B. P. Abbott, R. Abbott, T. D. Abbott, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov

Physics & Astronomy Faculty Publications

On September 14, 2015, at 0950:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) simultaneously observed the binary black hole merger GW150914. We report the results of a matched-filter search using relativistic models of compact-object binaries that recovered GW150914 as the most significant event during the coincident observations between the two LIGO detectors from September 12 to October 20, 2015 GW150914 was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203000 years, equivalent to a significance greater than 5.1 σ.


Galaxies Probing Galaxies At High Resolution: Co-Rotating Gas Associated With A Milky Way Analog At Z = 0.4, Aleksandar M. Diamond-Stanic, Alison L. Coil, John Moustakas, Christy A. Tremonti, Paul H. Sell, Alexander J. Mendez, Ryan C. Hickox, Greg H. Rudnick Jun 2016

Galaxies Probing Galaxies At High Resolution: Co-Rotating Gas Associated With A Milky Way Analog At Z = 0.4, Aleksandar M. Diamond-Stanic, Alison L. Coil, John Moustakas, Christy A. Tremonti, Paul H. Sell, Alexander J. Mendez, Ryan C. Hickox, Greg H. Rudnick

Dartmouth Scholarship

We present results on gas flows in the halo of a Milky-Way-like galaxy at z = 0.413 based on high-resolution spectroscopy of a background galaxy. This is the first study of circumgalactic gas at high spectral resolution toward an extended background source (i.e., a galaxy rather than a quasar). Using long-slit spectroscopy of the foreground galaxy, we observe spatially extended Hα emission with a circular rotation velocity v circ ≈ 270 km s−1. Using echelle spectroscopy of the background galaxy, we detect and absorption lines at an impact parameter ρ= 27 kpc that are blueshifted from systemic …


Plasma Trimethylamine N-Oxide, A Gut Microbe–Generated Phosphatidylcholine Metabolite, Is Associated With Atherosclerotic Burden, Vichai Senthong, Xinmin S. Li, Timothy Hudec, John Coughlin, Yuping Wu, Bruce Levison, Zeneng Wang, Stanley L. Hazen, W.H. Wilson Tang Jun 2016

Plasma Trimethylamine N-Oxide, A Gut Microbe–Generated Phosphatidylcholine Metabolite, Is Associated With Atherosclerotic Burden, Vichai Senthong, Xinmin S. Li, Timothy Hudec, John Coughlin, Yuping Wu, Bruce Levison, Zeneng Wang, Stanley L. Hazen, W.H. Wilson Tang

Mathematics and Statistics Faculty Publications

Background: Trimethylamine N-oxide (TMAO), a gut microbiota metabolite from dietary phosphatidylcholine, has mechanistic links to atherosclerotic coronary artery disease (CAD) pathogenesis and is associated with adverse outcomes. Objectives: This study sought to examine the relationship between plasma TMAO levels and the complexity and burden of CAD and degree of subclinical myonecrosis. Methods: We studied 353 consecutive stable patients with evidence of atherosclerotic CAD detected by elective coronary angiography between 2012 and 2014. Their high-sensitivity cardiac troponin T (hs-cTnT) levels were measured. SYNTAX (Synergy Between Percutaneous Coronary Intervention With Taxus and Cardiac Surgery) scores and lesion characteristics were used to quantify …


The Design And Testing Of A Novel Batch Photocatalytic Reactor And Photocatalyst, Shawn Sasser Jun 2016

The Design And Testing Of A Novel Batch Photocatalytic Reactor And Photocatalyst, Shawn Sasser

USF Tampa Graduate Theses and Dissertations

With an ever-increasing human population, the importance in having sustainable energy resources is becoming increasingly evident, as the current energy habits have brought about massive atmospheric pollution in the form of CO2 emissions, resulting in a rise in the average global temperature. To battle the effects of climate change, many alternative energy resources have been investigated. Among these, photocatalytic conversion of CO2 to renewable hydrocarbon fuels such as methane and methanol is one of the most desirable, as it provides the opportunity to utilize the sun’s energy to convert CO2 to renewable fuels. The work in this …


Observing Gravitational-Wave Transient Gw150914 With Minimal Assumptions, B. P. Abbott, K. Gill, B. Hughey, M. Szczepańczyk, M. Zanolin, Et Al. Jun 2016

Observing Gravitational-Wave Transient Gw150914 With Minimal Assumptions, B. P. Abbott, K. Gill, B. Hughey, M. Szczepańczyk, M. Zanolin, Et Al.

Publications

The gravitational-wave signal GW150914 was first identified on September 14, 2015, by searches for short-duration gravitational-wave transients. These searches identify time-correlated transients in multiple detectors with minimal assumptions about the signal morphology, allowing them to be sensitive to gravitational waves emitted by a wide range of sources including binary black hole mergers. Over the observational period from September 12 to October 20, 2015, these transient searches were sensitive to binary black hole mergers similar to GW150914 to an average distance of ∼600  Mpc. In this paper, we describe the analyses that first detected GW150914 as well as the parameter estimation …


Effect Of Polymer Concentration Rotational Speed And Solvent Mixture On Fiber Formation Using Forcespinning®, Nancy Obregon, Victor Agubra, Madhab Pokhrel, Howard Campos, David Flores, David De La Garza, Yuanbing Mao, Javier Macossay-Torres, Mataz Alcoutlabi Jun 2016

Effect Of Polymer Concentration Rotational Speed And Solvent Mixture On Fiber Formation Using Forcespinning®, Nancy Obregon, Victor Agubra, Madhab Pokhrel, Howard Campos, David Flores, David De La Garza, Yuanbing Mao, Javier Macossay-Torres, Mataz Alcoutlabi

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Polycaprolactone (PCL) fibers were produced using Forcespinning® (FS). The effects of PCL concentration, solvent mixture, and the spinneret rotational speed on fiber formation were evaluated. The concentration of the polymer in the solvents was a critical determinant of the solution viscosity. Lower PCL concentrations resulted in low solution viscosities with a correspondingly low fiber production rate with many beads. Bead-free fibers with high production rate and uniform fiber diameter distribution were obtained from the optimum PCL concentration (i.e., 12.5 wt%) with tetrahydrofuran (THF) as the solvent. The addition of N, N-dimethylformamide (DMF) to the THF solvent promoted the gradual formation …