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Early Detection Of Mountain Pine Beetle Damage In Ponderosa Pine Forests Of The Black Hills Using Hyperspectral And Worldview-2 Data, Kyle Edward Mullen Jan 2016

Early Detection Of Mountain Pine Beetle Damage In Ponderosa Pine Forests Of The Black Hills Using Hyperspectral And Worldview-2 Data, Kyle Edward Mullen

All Graduate Theses, Dissertations, and Other Capstone Projects

A leading cause for mortality in the pine forests of western North America, the mountain pine beetle, has impacted over 400,000 acres of ponderosa pine forest in the Black Hills of South Dakota since 1996. Methods aimed at earlier detection, prior to visual manifestation of a mountain pine beetle damage in the tree crown, have not been successful because of the overlap and variability of spectral response between the initial stages of attack (green-attacked) and non-attacked tree crowns. Needle-level reflectance spectra was measured from green-attack and non-attack ponderosa pine trees in early spring following an infestation and analyzed using a …


The Role Of Amino Acids In The Nitrogen Cycle Of Peatlands, Tia Scarpelli Jan 2016

The Role Of Amino Acids In The Nitrogen Cycle Of Peatlands, Tia Scarpelli

Dissertations, Master's Theses and Master's Reports

Future release of carbon from peatlands in response to climate change may be impacted by nitrogen limitation. The current study considers the role of amino acids as a nitrogen source in peatlands. The total free amino acid (TFAA) concentration for peats ranged from 0-2.3 µM, and leucine was the primary contributor. The dominance of sedge or ericaceous shrub plant types did not significantly impact the TFAA pool. Ammonium concentrations were much greater than TFAA and nitrate concentrations. TFAA concentrations were greatest in spring and least in fall. The springtime maxima and summer decrease in concentrations were simulated in a modeling …


The Implications Of Climate Change For Nebraska: Summary Report Of Sector-Based Roundtable Discussions, Donald A. Wilhite, Kimberly Morrow Jan 2016

The Implications Of Climate Change For Nebraska: Summary Report Of Sector-Based Roundtable Discussions, Donald A. Wilhite, Kimberly Morrow

National Drought Mitigation Center: Faculty Publications

This report is the result of the work of many individuals that contributed to the success of the series of eight sector-based roundtable events that were held in September and October of 2015. First and foremost, we would like to thank the organizers and the organizations they represent for their leadership in bringing together a diverse set of key stakeholders to discuss the implications of climate change on their sector. It was such a pleasure to work with such a dedicated group of individuals. Second, we would like to thank the more than 350 people who participated in these discussions …


Effects Of Epichloë Coenophiala−Tall Fescue Symbiosis On Plant-Microbe-Soil Interactions In A Temperate Pasture, Lindsey C. Slaughter Jan 2016

Effects Of Epichloë Coenophiala−Tall Fescue Symbiosis On Plant-Microbe-Soil Interactions In A Temperate Pasture, Lindsey C. Slaughter

Theses and Dissertations--Plant and Soil Sciences

Plants interact in myriad ways with microorganisms to influence ecosystem processes such as nutrient cycling, which can regulate ecosystem response to global change. One important plant-microbe symbiosis occurs between cool-season grasses and asexual fungal Epichloë endophytes, such as tall fescue (Schedonorus arundinaceus) and Epichloë coenophiala. Because the common toxic strain of the endophyte (CTE) harms grazing livestock, non-livestock toxic endophyte (NTE) strains have been developed and are increasingly deployed in pastures. Little is known about how these symbioses impact other plant-microbe interactions and microbe-mediated soil processes in grassland ecosystems. I conducted three studies to determine how E. …


Hopper Bands: Locust Aggregation, Ryan C. Jones Jan 2016

Hopper Bands: Locust Aggregation, Ryan C. Jones

HMC Senior Theses

Locust swarms cause famine and hunger in parts of Sub-Saharan Africa as they travel across croplands and eat vegetation. Current models start with biological properties of locusts and analyze the macroscopic behavior of the system. These models exhibit the desired migratory behavior, but do so with too many parameters. To account for this, a new model, the Alignment and Intermittent Motion (AIM) model, is derived with minimal assumptions. AIM is constructed with regards to locust biology, allowing it to elicit biologically correct locust behavior: the most noteworthy being the fingering of hopper bands. A Particle-in-Cell method is used to optimize …


Modern And Fossil Callianassid Burrows Of The Bahamas: Comparisons And Implications For Paleoenvironmental Analysis, H. Allen Curran, Koji Seike Jan 2016

Modern And Fossil Callianassid Burrows Of The Bahamas: Comparisons And Implications For Paleoenvironmental Analysis, H. Allen Curran, Koji Seike

Geosciences: Faculty Publications

Reprinted from: Bosiljka Glumac & Michael Savarese (eds.), Proceedings of the 16th Symposium on the Geology of the Bahamas and Other Carbonate Regions:San Salvador, Gerace Research Center


Banning Metal Mining In Guatemala, Randall S. Abate, Raquel Aldana Jan 2016

Banning Metal Mining In Guatemala, Randall S. Abate, Raquel Aldana

Journal Publications

Metal mining is unsustainable for Guatemala and its harms insurmountable for its people. Guatemalans who oppose metal mining have been fighting for decades domestically and internationally against the environmental degradation and other human rights abuses from metal mining activities in the country with little to show for their efforts. The State is too weak and corrupt to offer much hope for reform. Guatemala requires extensive governance reforms to become the type of strong democracy capable of reaping the potential benefits of metal mining in its territory. This is a long-term project. Most Guatemalans opposed to metal mining already know this, …


Geochemical Processes And Controls Affecting Water Quality Of The Karst Area Of Big Creek Near Mt. Judea, Arkansas, V. Brahana, J. Nix, C. Kuyper, T. Turk, F. Usrey, S. Hodges, C. Bitting, K. Ficco, E. Pollock, R. Quick, B. Thompson, J. Murdoch Jan 2016

Geochemical Processes And Controls Affecting Water Quality Of The Karst Area Of Big Creek Near Mt. Judea, Arkansas, V. Brahana, J. Nix, C. Kuyper, T. Turk, F. Usrey, S. Hodges, C. Bitting, K. Ficco, E. Pollock, R. Quick, B. Thompson, J. Murdoch

Journal of the Arkansas Academy of Science

Karst regions typically are considered to be vulnerable with respect to various land-use activities, owing to the intimate association of surface and groundwater and lack of contaminant attenuation provided by most karst aquifers. Inasmuch as the soluble rocks of the karst landscape can be dissolved to create large, rapid-flow zones that compete successfully with surface streams, groundwater and subsurface flow represent a much larger component of the hydrologic budget in karst regions than in areas where non-soluble rocks predominate. Karst areas typically are distinguished by being unique, but some general approaches can be applied to characterize the hydrology of the …


The Impact Of Multiple Imputation On The Type Ii Error Rate Of The T Test, Tammy A. Grace Jan 2016

The Impact Of Multiple Imputation On The Type Ii Error Rate Of The T Test, Tammy A. Grace

Wayne State University Dissertations

ABSTRACT

THE IMPACT OF MULTIPLE IMPUTATION ON THE TYPE II ERROR RATE OF

THE T TEST

by

TAMMY A. GRACE

August 2016

Advisor: Shlomo Sawilowsky, PhD

Major: Evaluation and Research

Degree: Doctor of Philosophy

The National Academy of Science identified numerous high priority areas for missing data research. This study addresses several of those areas by systematically investigating the impact of multiple imputation on the rejection rate of the independent samples t test under varying conditions of sample size, effect size, fraction of missing data, distribution shape, and alpha. In addition to addressing gaps in the missing data literature, this …


Water Management Efficiency In The Food And Beverage Industry, Maria Del C Reyes Torres Jan 2016

Water Management Efficiency In The Food And Beverage Industry, Maria Del C Reyes Torres

Walden Dissertations and Doctoral Studies

Water is critical for food production, food security, and health. Water quality management influences freshwater sustainability, land, and energy administration. Global agriculture accounts for more than 70% of all water consumption; the fertilizer, manure, and pesticide overspills are chief sources of water pollution worldwide. On a global scale, food-related waste directly impacts local food production and water resource management. The purpose of this multiple-case study on the food and beverage (FB) industry in the State of Georgia was to identify successful strategies for improving water management efficiency. The concepts of systems thinking, adaptive resource management, and integrated water resource management …


Methylmercury Exposure Via Canned Tuna Fish Consumption And Breast Cancer, Jennifer Bodenrader Jan 2016

Methylmercury Exposure Via Canned Tuna Fish Consumption And Breast Cancer, Jennifer Bodenrader

Walden Dissertations and Doctoral Studies

Widespread consumption of canned tuna fish since the 1950s may explain some of the increase in breast cancer prevalence in the United States and Europe. Although canned tuna is the primary source of human exposure to methylmercury, its role as an estrogen activating metalloestrogen has been overlooked in the etiology and incidence of breast cancer. Carcinogenic theory asserts that increased exposure to estrogen elevates the risk of breast cancer. The purpose of this population-based, case control study was to examine the association between canned tuna consumption, total blood mercury, and breast cancer in the NHANES 2003-2006 surveys. A multivariable logistic …


Mechanisms Of Antixenosis And Antibiosis Of Ash Against Emerald Ash Borer, Chad Michael Rigsby Jan 2016

Mechanisms Of Antixenosis And Antibiosis Of Ash Against Emerald Ash Borer, Chad Michael Rigsby

Browse all Theses and Dissertations

Emerald ash borer (EAB), Agrilus planipennis (Coleoptera: Buprestidae), is an invasive forest pest causing widespread mortality of ash (Fraxinus spp.) in North America. Host resistance research and the development of resistant hosts offers a promising strategy for the long-term conservation of ash and management of EAB. Manchurian ash (F. mandshurica) shares an evolutionary history with EAB in Asia, resulting in its greater resistance relative to naive North American ashes. In the following studies I investigate antixenosis and antibiosis mechanisms of resistant and susceptible ashes. Antixenosis in Manchurian ash was demonstrated by quantifying substantially lower oviposition on this species relative to …


Benthic Marine Calcifiers Coexist With Caco3-Undersaturated Seawater Worldwide, Mario Lebrato, Andreas J. Andersson, Justin Baker Ries, Richard B. Aronson, Miles D. Lamare, Wolfgang Koeve, Andreas Oschlies, Maria Débora Iglesias-Rodríguez, Sven Thatje, M. Amsler, Stephanie C. Vos, D. O. B. Jones, H. A. Ruhl, A. R. Gates, J. B. Mcclintock Jan 2016

Benthic Marine Calcifiers Coexist With Caco3-Undersaturated Seawater Worldwide, Mario Lebrato, Andreas J. Andersson, Justin Baker Ries, Richard B. Aronson, Miles D. Lamare, Wolfgang Koeve, Andreas Oschlies, Maria Débora Iglesias-Rodríguez, Sven Thatje, M. Amsler, Stephanie C. Vos, D. O. B. Jones, H. A. Ruhl, A. R. Gates, J. B. Mcclintock

Ocean Engineering and Marine Sciences Faculty Publications

Ocean acidification and decreasing seawater saturation state with respect to calcium carbonate (CaCO3) minerals have raised concerns about the consequences to marine organisms that build CaCO3 structures. A large proportion of benthic marine calcifiers incorporate Mg2+ into their skeletons (Mg-calcite), which, in general, reduces mineral stability. The relative vulnerability of some marine calcifiers to ocean acidification appears linked to the relative solubility of their shell or skeletal mineralogy, although some organisms have sophisticated mechanisms for constructing and maintaining their CaCO3 structures causing deviation from this dependence. Nevertheless, few studies consider seawater saturation state with respect to the actual Mg-calcite mineralogy …


Using Satellite Vegetation And Compound Topographic Indices To Maphighly Erodible Cropland Buffers For Cellulosic Biofuel Cropdevelopments In Eastern Nebraska, Usa, Yingxin Gu, Bruce K. Wylie Jan 2016

Using Satellite Vegetation And Compound Topographic Indices To Maphighly Erodible Cropland Buffers For Cellulosic Biofuel Cropdevelopments In Eastern Nebraska, Usa, Yingxin Gu, Bruce K. Wylie

United States Geological Survey: Staff Publications

Cultivating annual row crops in high topographic relief waterway buffers has negative environmental effects and can be environmentally unsustainable. Growing perennial grasses such as switchgrass(Panicum virgatum L.) for biomass (e.g., cellulosic biofuel feedstocks) instead of annual row crops in these high relief waterway buffers can improve local environmental conditions (e.g., reduce soil erosion and improve water quality through lower use of fertilizers and pesticides) and ecosystem services (e.g.,minimize drought and flood impacts on production; improve wildlife habitat, plant vigor, and nitro-gen retention due to post-senescence harvest for cellulosic biofuels; and serve as carbon sinks). The main objectives of this …


Amino Acid Specific Stable Nitrogen Isotope Values In Avian Tissues: Insights From Captive American Kestrels And Wild Herring Gulls, C.E. Hebert, B.N. Popp, K.J. Fernie, C. Ka’Apu-Lyons, B.A. Rattner, N. Wallsgrove Jan 2016

Amino Acid Specific Stable Nitrogen Isotope Values In Avian Tissues: Insights From Captive American Kestrels And Wild Herring Gulls, C.E. Hebert, B.N. Popp, K.J. Fernie, C. Ka’Apu-Lyons, B.A. Rattner, N. Wallsgrove

United States Geological Survey: Staff Publications

Through laboratory and field studies, the utility of amino acid compound-specific nitrogen isotope analysis (AA-CSIA) in avian studies is investigated. Captive American kestrels (Falco sparverius) were fed an isotopically characterized diet and patterns in δ15N values of amino acids (AAs) were compared to those in their tissues (muscle and red blood cells) and food. Based upon nitrogen isotope discrimination between diet and kestrel tissues, AAs could mostly be categorized as source AAs (retaining baseline δ15N values) and trophic AAs (showing 15N enrichment). Trophic discrimination factors based upon the source (phenylalanine, Phe) and trophic (glutamic acid, Glu) AAs were 4.1 (muscle) …


Amino Acid Specific Stable Nitrogen Isotope Values In Avian Tissues: Insights From Captive American Kestrels And Wild Herring Gulls, C.E. Hebert, B.N. Popp, K.J. Fernie, C. Ka’Apu-Lyons, B.A. Rattner, N. Wallsgrove Jan 2016

Amino Acid Specific Stable Nitrogen Isotope Values In Avian Tissues: Insights From Captive American Kestrels And Wild Herring Gulls, C.E. Hebert, B.N. Popp, K.J. Fernie, C. Ka’Apu-Lyons, B.A. Rattner, N. Wallsgrove

United States Geological Survey: Staff Publications

Through laboratory and field studies, the utility of amino acid compound-specific nitrogen isotope analysis (AA-CSIA) in avian studies is investigated. Captive American kestrels (Falco sparverius) were fed an isotopically characterized diet and patterns in δ15N values of amino acids (AAs) were compared to those in their tissues (muscle and red blood cells) and food. Based upon nitrogen isotope discrimination between diet and kestrel tissues, AAs could mostly be categorized as source AAs (retaining baseline δ15N values) and trophic AAs (showing 15N enrichment). Trophic discrimination factors based upon the source (phenylalanine, Phe) and trophic (glutamic acid, Glu) AAs were 4.1 (muscle) …


Computer-Assisted Cobb Angle Measurement From Posteroanterior Radiographs By A Curve Fitting Method, İbrahi̇m Yildiz Jan 2016

Computer-Assisted Cobb Angle Measurement From Posteroanterior Radiographs By A Curve Fitting Method, İbrahi̇m Yildiz

Turkish Journal of Electrical Engineering and Computer Sciences

Incorrect determination of the top or end vertebrae of a scoliotic curve causes measurement errors when using the Cobb method. Such problems are due to subjectivity. This study was performed to minimize subjectivity by using a curve fitting method. A digitally scanned posteroanterior radiographic image was used for each patient. User-defined midpoints of the curvature, which indicate the midpoints of the vertebrae, were used to fit the polynomial equation. The locations of the top and end vertebrae were calculated using the first derivative of the fitted polynomial equation to obtain the analytical Cobb angle. The interobserver technical error of measurements …


The Evolution Of The Sugarcoated American Food Market And The Paradox Of Artificial Sweeteners, Mary Moses Hitt Jan 2016

The Evolution Of The Sugarcoated American Food Market And The Paradox Of Artificial Sweeteners, Mary Moses Hitt

Honors Theses

Living in present-day America makes it hard to imagine an era when sugar was not as inexpensive and readily available as it is now. It is in little colorful packets on restaurant tables, filled to the brim in jars at coffee shops, or mixed into candy products located at the beginning of every cash register. Today, sugar is one of, if not, the most widely consumed food products in the world, but our love for sugar is nothing new. Humans have been experiencing the bliss triggered by sweet-tasting foods since their earliest diets, which included fruits and honey. Our diets …


Paleolithic Protection In A Western World: A Look Into Preagricultural Nutrition As A Remedy For The Diseases Of Civilization, Emilie R. Caron Jan 2016

Paleolithic Protection In A Western World: A Look Into Preagricultural Nutrition As A Remedy For The Diseases Of Civilization, Emilie R. Caron

Honors Theses

The aim of this investigation is to discover the associations of the Western diet to noncommunicable diseases and to determine if a reversion to a Paleolithic diet will provide treatment and prevention of these diseases. Noncommunicable diseases, otherwise known as Diseases of Civilization, are lifestyle influenced diseases and encompass obesity, diabetes mellitus, cardiovascular disease, and associated cancers. Incidences of these diseases have skyrocketed in the past century and show no signs of decline. Since 1900, the death rates due to heart disease and cancer have risen to account for 47% of total deaths in the United States in 2010. (Tippett, …


Effects Of Citric Acid Coated And Uncoated Cerium Oxide Nanoparticles In Tomato (Solanum Lycopersicum) Plants, Ana Cecilia Barrios Jan 2016

Effects Of Citric Acid Coated And Uncoated Cerium Oxide Nanoparticles In Tomato (Solanum Lycopersicum) Plants, Ana Cecilia Barrios

Open Access Theses & Dissertations

This research was performed to examine the physiological and biochemical effects of bare (nCeO2) and citric acid coated (nCeO2+CA) cerium oxide nanoparticles in tomato (Solanum lycopersicum). Plants were germinated and grown to full maturity in soil amended with 0-500 mg/kg and periodically analyzed using ICP-OES/MS and other spectroscopic and biochemical techniques. Although Ce in tissues increased as the external nCeO2 increased, there were no visible signs of toxicity. In mature plants, nCeO2 induced developmental changes and altered nutritional quality (essential elements) in fruits. On the other hand, nCeO2+CA affected fruit carbohydrate composition (sugars and starch). This study gives insights on …


Modulation Of The Physiological And Biochemical Effects Of Copper Nanoparticles In Kidney Beans (Phaseouls Vulgaris) Treated By Kinetin, Suzanne Annette Apodaca Jan 2016

Modulation Of The Physiological And Biochemical Effects Of Copper Nanoparticles In Kidney Beans (Phaseouls Vulgaris) Treated By Kinetin, Suzanne Annette Apodaca

Open Access Theses & Dissertations

It is imperative to not only understand the impact of engineered nanomaterials (ENMs) in edible plants, but also the interactions they have with various additives used in agriculture. In this study, kidney bean plants were grown in potting soil treated with nano copper (nCu), bulk copper (bCu), and copper chloride (CuCl2) at concentrations of 0, 50, and 100 mg/kg for 55 and 90 days. At 15 days of growth, 0, 10, and 100 μm of kinetin (KN) were applied to plants. Plant tissue samples were harvested at 55 days and seeds were reaped at 90 days. Physiological and biochemical parameters …


Identifying Non-Classical Active Sites As A Tool For Enzyme Inhibition, Marisol Serrano Jan 2016

Identifying Non-Classical Active Sites As A Tool For Enzyme Inhibition, Marisol Serrano

Open Access Theses & Dissertations

Chagas disease, caused by the parasite Trypanosoma cruzi, is an endemic life-threatening disease that affects mainly the heart. It remains the leading cause of heart failure in Latin American countries. Since current treatments against this parasite are highly toxic and somewhat ineffective, novel and more efficacious types of interventions are desired. Cruzain, identified as the major cathepsin for T. cruzi, plays a major role in the parasite's life cycle; making this enzyme very attractive for potential trypanocidal drugs discovery. The recombinant cruzain is synthesized as a zymogenic pro-protein (PCZN) which possesses a pro domain and a catalytic domain. In this …


Bioavailability Of Metal/Metal Oxide Nanomaterials And Their Effects On The Physiology Of Plants, Nubia Zuverza Mena Jan 2016

Bioavailability Of Metal/Metal Oxide Nanomaterials And Their Effects On The Physiology Of Plants, Nubia Zuverza Mena

Open Access Theses & Dissertations

Nanoparticles (NPs) contained in consumer products will undoubtedly reach the environment. Engineered nanomaterials (ENMs) may cause physiological and biochemical alterations in plants and, therefore, have noteworthy effects on their growth and proliferation. Edible plants are a means through which NPs can reach organisms of higher trophic levels that feed on them. Previous studies have demonstrated that there are strong interactions between NPs and terrestrial plants. This project intends to evaluate the impacts that various commercially available NPs have on plants. Copper (Cu) nanomaterials and conventional Cu compounds were compared in cilantro plants (Chapter 2). In addition, changes in radish sprouts …


Pro-Fit: Exercise With Friends, Saumil Dharia, Vijesh Jain, Jvalant Patel, Jainikkumar Vora, Rizen Yamauchi, Magdalini Eirinaki, Iraklis Varlamis Jan 2016

Pro-Fit: Exercise With Friends, Saumil Dharia, Vijesh Jain, Jvalant Patel, Jainikkumar Vora, Rizen Yamauchi, Magdalini Eirinaki, Iraklis Varlamis

Faculty Publications

The advancements in wearable technology, where embedded accelerometers, gyroscopes and other sensors enable the users to actively monitor their activity have made it easier for individuals to pursue a healthy lifestyle. However, most of the existing applications expect continuous commitment from the end users, who need to proactively interact with the application in order to connect with friends and attain their goals. These applications fail to engage and motivate users who have busy schedules, or are not as committed and self-motivated. In this work, we present PRO-Fit, a personalized fitness assistant application that employs machine learning and recommendation algorithms in …


Chromium Redox Speciation In Food Samples, Krystyna Pyrzynska Jan 2016

Chromium Redox Speciation In Food Samples, Krystyna Pyrzynska

Turkish Journal of Chemistry

Chromium is an element with important biological characteristics, depending on its different species. Cr(III) is considered as essential; however, the Cr(VI) form is classified as carcinogenic.~For this reason, speciation analysis in food samples is a very important question. The proposed data procedures for chromium redox speciation in the literature can be divided into those with the use of online hyphenated techniques and those where appropriate sample pretreatment is necessary. The strategies for nonchromatographic speciation are mainly based on selective liquid--liquid extraction procedures, coprecipitation, selective separation of chromium species using a solid phase extraction column, or complexation reactions. In this paper, …


Falls And Related Injuries Based On Surveillance Data: U.S. Hospital Emergency Departments, George K. Quarranttey Jan 2016

Falls And Related Injuries Based On Surveillance Data: U.S. Hospital Emergency Departments, George K. Quarranttey

Walden Dissertations and Doctoral Studies

Falls can lead to unintentional injuries and possibly death, making falls an important public health problem in terms of related health care cost, incurred disabilities, and years of life lost. Approximately 1 in every 3 Americans ages 65 years and older is at risk of falling at least once every year. Children, young adults, and middle-aged adults are also vulnerable to falls. The purpose of this study was to examine the epidemiology of falls and fall-related injuries using surveillance data from nationally representative samples of hospital emergency departments in United States. The study was guided by a social-ecological model on …


Comparative Density Functional Study Of Antioxidative Activity Of The Hydroxybenzoic Acids And Their Anions, Zoran Markovic, Jelena Djorovic, Jasmina M. Dimitric Markovic, Radomir Biocanin, Dragan Amic Jan 2016

Comparative Density Functional Study Of Antioxidative Activity Of The Hydroxybenzoic Acids And Their Anions, Zoran Markovic, Jelena Djorovic, Jasmina M. Dimitric Markovic, Radomir Biocanin, Dragan Amic

Turkish Journal of Chemistry

Hydroxybenzoic acids (HBAs) and their anions play an important role in the food and pharmaceutical industries because of their antioxidant activity. In this study, we examined the mechanisms of the free radical scavenging action of HBAs and their anions using density functional theory (DFT) methods. Reaction enthalpies related to the mechanisms of free radical scavenging by the investigated species were calculated by DFT methods in water, DMSO, pentylethanoate, and benzene. Hydrogen atom transfer (HAT) is a preferred reaction pathway in benzene, while sequential proton loss electron transfer (SPLET) is a predominant reaction pathway in polar solvents, water, and DMSO for …


Speciation Of Inorganic Selenium By Solid Phase Extraction Using Nanozirconium Oxide/Boron Oxide Composite Material, Hakan Erdoğan, Özcan Yalçinkaya, Ali̇ Rehber Türker Jan 2016

Speciation Of Inorganic Selenium By Solid Phase Extraction Using Nanozirconium Oxide/Boron Oxide Composite Material, Hakan Erdoğan, Özcan Yalçinkaya, Ali̇ Rehber Türker

Turkish Journal of Chemistry

The speciation and preconcentration of selenium were carried out by solid phase extraction using nanozirconium oxide/boron oxide (ZrO$_{2}$/B$_{2}$O$_{3})$. Electrothermal atomic absorption spectrometry (ETAAS) was used for detection. This preconcentration and/or speciation method depends on the retention of Se(IV) ions selectively as its ammonium pyrrolidine dithiocarbamate (APDC) complex on the sorbent. The effects of pH, flow rate, and volume of sample solution and eluent type were investigated for determining the optimum preconcentration and speciation conditions. The effects of other ions that may interfere with the determination and speciation of selenium were also investigated. Moreover, the analytical performance criteria of the method …


Mn-Doped Zns Quantum Dots As A Room-Temperature Phosphorescent Probe For Analysis Of Glutamic Acid In Foodstuffs, Hayri̇ye Eda Şatana Kara, Burak Demi̇rhan, Buket Er Demi̇rhan Jan 2016

Mn-Doped Zns Quantum Dots As A Room-Temperature Phosphorescent Probe For Analysis Of Glutamic Acid In Foodstuffs, Hayri̇ye Eda Şatana Kara, Burak Demi̇rhan, Buket Er Demi̇rhan

Turkish Journal of Chemistry

L-cysteine-capped Mn-doped ZnS quantum dots (QDs) were used for the determination of glutamic acid in foodstuffs. This method is based on measurement of the quenching of the phosphorescence intensity of the QDs after interacting with glutamic acid. A linear response was observed from 50 to 500 ng mL$^{-1}$ glutamic acid with a limit of detection of 6.79 ng mL$^{-1}$. Room temperature phosphorescence (RTP) intensity of the QDs was quenched rapidly upon the addition of the quencher and the reaction reached equilibrium within 2 min. The quenching mechanism of phosphorescence of Mn-doped ZnS QDs by glutamic acid is dynamic and the …


Determination Of Hexavalent Chromium In Aqueous And Alkaline Soil Extracts, Tsvetomil Voyslavov, Stefan Tsakovski, Sonya Ganeva Jan 2016

Determination Of Hexavalent Chromium In Aqueous And Alkaline Soil Extracts, Tsvetomil Voyslavov, Stefan Tsakovski, Sonya Ganeva

Turkish Journal of Chemistry

A fast, simple, and reliable method for determination of hexavalent chromium species in soil aqueous and alkaline extracts has been developed. The procedure is based on the ion-pair extraction of Cr(VI) with methyltrioctylammonium chloride (Aliquat 336) into xylene. The extract is analyzed by flame (FAAS) or electrothermal atomic absorption spectrometry (ETAAS). The method allows the detection of up to 2 mg kg$^{-1}$ Cr(VI) by FAAS and up to 25 $\mu $g kg$^{-1}$ Cr(VI) by ETAAS. The relative standard deviation varied in the range 2%-12% depending on the Cr(VI) levels in the samples. The analysis of certified reference material CRM041-30G Chromium …