Physical Sciences and Mathematics Commons^™

The Carriers Of The Interstellar Unidentified Infrared Emission Features: Constraints From The Interstellar C-H Stretching Features At 3.2-3.5 Μm, Xuejuan Yang, Rainer Glaser, Aigen Li, Jianxin Zhong

Chemistry Faculty Research & Creative Works

The unidentified infrared emission (UIE) features at 3.3, 6.2, 7.7, 8.6, and 11.3 μm, commonly attributed to polycyclic aromatic hydrocarbon (PAH) molecules, have recently been ascribed to mixed aromatic/aliphatic organic nanoparticles. More recently, an upper limit of <9% was placed on the aliphatic fraction (i.e., the fraction of carbon atoms in aliphatic form) of the UIE carriers based on the observed intensities of the 3.4 μm and 3.3 μm emission features by attributing them to aliphatic and aromatic C-H stretching modes, respectively, and assuming A _3.4/A _3.3 ≈ 0.68 derived from a small set of aliphatic and aromatic compounds, where A _3.4 and A _3.3 are, respectively, the band strengths of the 3.4 μm aliphatic and 3.3 μm aromatic C-H bonds. To improve the estimate of the aliphatic fraction of the UIE carriers, here we analyze 35 UIE sources exhibiting both the 3.3 μm and …

Structural And Magnetic Properties Of La₀.₇Sr₀.₃Mn₁₋ₓniₓo₃ (X ≤ 0.4), Thomas F. Creel, Jinbo Yang, Mehmet Kahveci, Satish K. Malik, Sylvio Quezado, Oran Allan Pringle, William B. Yelon, William Joseph James

Physics Faculty Research & Creative Works

We have studied the structural and magnetic properties of La_0.7Sr_0.3Mn_1-xNi_xO₃ (x = 0.05, 0.1, 0.20, 0.30, and 0.40) perovskites using x-ray and neutron diffraction and magnetic measurements. Our data consist of neutron (γ = 1.479Å) and x-ray (γ = 1.5481Å; Cu Kα) powder diffraction and magnetization measurements. We previously suggested these systems transition from ferromagnetic to antiferromagnetic ordering with the intermediate concentrations containing coexisting domains of ferromagnetically and antiferromagnetically ordered states. Upon further detailed examination, we find that the samples are homogeneous and that neutron data can be fitted to a …

Synthesis And Fading Of Eighteenth-Century Prussian Blue Pigments: A Combined Study By Spectroscopic And Diffractive Techniques Using Laboratory And Synchrotron Radiation Sources, Louise Samain, Fernande Grandjean, Gary J. Long, Pauline Martinetto, Pierre Bordet, Jana Sanyova, David Strivay

Chemistry Faculty Research & Creative Works

Prussian blue, a hydrated iron(III) hexacyanoferrate(II) complex, is a synthetic pigment discovered in Berlin in 1704. Because of both its highly intense color and its low cost, Prussian blue was widely used as a pigment in paintings until the 1970s. The early preparative methods were rapidly recognized as a contributory factor in the fading of the pigment, a fading already known by the mid-eighteenth century. Herein two typical eighteenth-century empirical recipes have been reproduced and the resulting pigment analyzed to better understand the reasons for this fading. X-ray absorption and Mössbauer spectroscopy indicated that the early syntheses lead to Prussian …

Site-Specific Inter-Strand Cross-Links Of Dna Duplexes, Miao Ye, Johan Guillame, Yu Liu, Ruojie Sha, Risheng Wang, Nadrian C. Seeman, James W. Canary

Chemistry Faculty Research & Creative Works

We report the development of technology that allows inter-strand coupling across various positions within one turn of DNA. Four 2'-modified nucleotides were synthesized as protected phosphoramidites and incorporated into DNA oligonucleotides. The modified nucleotides contain either 5-atom or 16-atom linker components, with either amine or carboxylic acid functional groups at their termini, forming 10 or 32 atom (11 or 33 bond) linkages. Chemical coupling of the amine and carboxylate groups in designed strands resulted in the formation of an amide bond. Coupling efficiency as a function of trajectory distance between the individual linker components was examined. For those nucleotides capable …

Link Between Cancer And Alzheimer Disease Via Oxidative Stress Induced By Nitric Oxide-Dependent Mitochondrial Dna Overproliferation And Deletion, Gjumrakch Aliev, Mark E. Obrenovich, Shams Tabrez, Nasimudeen R. Jabir, Prakash Reddy, Yi Li, Geoffrey Burnstock, Ramon Cacabelos, Mohammad Amjad Kamal

Chemistry Faculty Research & Creative Works

Nitric oxide- (NO-) dependent oxidative stress results in mitochondrial ultrastructural alterations and DNA damage in cases of Alzheimer disease (AD). However, little is known about these pathways in human cancers, especially during the development as well as the progression of primary brain tumors and metastatic colorectal cancer. One of the key features of tumors is the deficiency in tissue energy that accompanies mitochondrial lesions and formation of the hypoxic smaller sized mitochondria with ultrastructural abnormalities. We speculate that mitochondrial involvement may play a significant role in the etiopathogenesis of cancer. Recent studies also demonstrate a potential link between AD and …

Sector Expansion And Elliptical Modeling Of Blue-Gray Ovoids For Basal Cell Carcinoma Discrimination In Dermoscopy Images, Pelin Guvenc, Robert W. Leander, Serkan Kefel, William V. Stoecker, Ryan K. Rader, Kristen A. Hinton, Sherea Monica Stricklin, Harold S. Rabinovitz, Margaret C. Oliviero, Randy Hays Moss

Chemistry Faculty Research & Creative Works

Background: Blue-gray ovoids (B-GOs), a critical dermoscopic structure for basal cell carcinoma (BCC), offer an opportunity for automatic detection of BCC. Due to variation in size and color, B-GOs can be easily mistaken for similar structures in benign lesions. Analysis of these structures could afford accurate characterization and automatic recognition of B-GOs, furthering the goal of automatic BCC detection. This study utilizes a novel segmentation method to discriminate B-GOs from their benign mimics.

Methods: Contact dermoscopy images of 68 confirmed BCCs with B-GOs were obtained. Another set of 131 contact dermoscopic images of benign lesions possessing B-GO mimics provided a …

Surface Temperature Effects On The Dynamics Of N₂ Eley-Rideal Recombination On W(100), Ernesto Quintas-Sánchez, C. Crespos, P. Larrégaray, J. C. Rayez, L. Martin-Gondre, J. Rubayo-Soneira

Chemistry Faculty Research & Creative Works

Quasiclassical trajectories simulations are performed to study the influence of surface temperature on the dynamics of a N atom colliding a N-preadsorbed W(100) surface under normal incidence. A generalized Langevin surface oscillator scheme is used to allow energy transfer between the nitrogen atoms and the surface. The influence of the surface temperature on the N₂ formed molecules via Eley-Rideal recombination is analyzed at T = 300, 800, and 1500 K. Ro-vibrational distributions of the N₂ molecules are only slightly affected by the presence of the thermal bath whereas kinetic energy is rather strongly decreased when going from a …

Intercalation And Delamination Of Layered Carbides And Carbonitrides, Olha Mashtalir, Michael Naguib, Vadym Mochalin, Yohan Dall'agnese, Min Heon, Michel W. Barsoum, Yury G. Gogotsi

Chemistry Faculty Research & Creative Works

Intercalation and delamination of two-dimensional solids in many cases is a requisite step for exploiting their unique properties. Herein we report on the intercalation of two-dimensional Ti₃C₂, Ti₃ CN and TiNbC - so called MXenes. Intercalation of hydrazine, and its co-intercalation with N,N-dimethylformamide, resulted in increases of the c-lattice parameters of surface functionalized f-Ti₃C₂, from 19.5 to 25.48 and 26.8 Å, respectively. Urea is also intercalated into f-Ti₃C₂. Molecular dynamics simulations suggest that a hydrazine monolayer intercalates between f-Ti₃C₂ layers. Hydrazine is also intercalated …

In Vivo Ultrasonic Detection Of Polyurea Crosslinked Silica Aerogel Implants, Firouzeh Sabri, Merry E. Sebelik, Ryan K. Meacham, John Dudley Boughter, Mitchell J. Challis, Nicholas Leventis

Chemistry Faculty Research & Creative Works

Background:Polyurea crosslinked silica aerogels are highly porous, lightweight, and mechanically strong materials with great potential for in vivo applications. Recent in vivo and in vitro studies have demonstrated the biocompatibility of this type of aerogel. the highly porous nature of aerogels allows for exceptional thermal, electric, and acoustic insulating capabilities that can be taken advantage of for non-invasive external imaging techniques. Sound-based detection of implants is a low cost, non-invasive, portable, and rapid technique that is routinely used and readily available in major clinics and hospitals.Methodology:In this study the first in vivo ultrasound response of polyurea crosslinked silica aerogel implants …

Luminescent Laf₃:Ce-Doped Organically Modified Nanoporous Silica Xerogels, Mingzhen Yao, Ryan Hall, Wei Chen, Dhairyashil Mohite, Nicholas Leventis, N. Lu, J. Wang, M. J. Kim, H. Luo, Hongbing Lu

Chemistry Faculty Research & Creative Works

Organically modified silica compounds (ORMOSILs) were synthesized by a sol-gel method from amine-functionalized 3-aminopropyl triethoxylsilane and tetramethylorthosilicate and were doped in situ with LaF₃:Ce nanoparticles, which in turn were prepared either in water or in ethanol. Doped ORMOSILs display strong photoluminescence either by UV or X-ray excitation and maintain good transparency up to a loading level of 15.66% w/w. The TEM observations demonstrate that ORMOSILs remain nanoporous with pore diameters in the 5-10 nm range. LaF₃:Ce nanoparticles doped into the ORMOSILs are rod-like, 5 nm in diameter and 10-15 nm in length. Compression testing indicates that …

Polybenzoxazine Aerogels: Synthesis, Characterization, Conversion To Porous Carbons, And Energetic Composites, Shruti Mahadik-Khanolkar

Doctoral Dissertations

"Aerogels are nanoporous, low-density bulk objects, consisting of three-dimensional assemblies of nanoparticle. Structured similarly, polymeric aerogels are emerging as a mechanically strong alternative to traditional silica aerogels, which are fragile. Amongst polymeric aerogels, those based on polybenzoxazine (PBO - a type of phenolic resin), are extremely robust and comprise an economic alternative to resorcinol-formaldehyde aerogels, also a class of phenolic resins, as the main source of carbon aerogels. The drawback of the PBO chemistry has been the long (days) processing time at high-temperatures (>130 ºC). Herewith, we have developed an energy- and time-efficient process to PBO aerogels by inducing …

Creating New Superconducting & Semiconducting Nanomaterials And Investingating The Effect Of Reduced Dimensionality On Their Properties, Sukhada Mishra

Doctoral Dissertations

"The field of nanomaterials has continued to attract researchers to understand the fundamentals and to investigate potential applications in the fields of semiconductor physics, microfabrication, nanomedicine, surface sciences etc. One of the most critical aspects of the nanomaterials research is to establish synthetic protocols, which can address the underlying product requirements of reproducibility, homogenous morphology and controlled elemental composition. We have focused our research in exploring synthetic routes for the synthesis of superconducting and semiconducting nanomaterials and analyze their structure--property relationship through detailed characterizations. The first part of dissertation is focused on the synthesis of superconducting FeSe nanostructures using catalyst …

Isocyanate-Derived Organic Aerogels: Polyurethanes, Polyureas, Polyamides And Polyimides, Chakkaravarthy Chidambareswarapattar

Doctoral Dissertations

"Aerogels are 3D assemblies of nanoparticles with high open porosity and high surface area, and are pursued for their low density, low thermal conductivity, low dielectric constant and high acoustic attenuation. The foundation for those exceptional properties is their complex hierarchical solid framework (agglomerates of porous, fractal secondary nanoparticles). On the down side, however, aerogels are also fragile materials. The mechanical strength of silica aerogels has been improved by crosslinking the framework with organic polymers. The crosslinking polymer has been assumed to form a conformal coating on the surface of the skeletal framework bridging covalently the elementary building blocks. However, …

Fundamental Properties Of Colloidal Unimolecular Polymer Particles, Minghang Chen

Doctoral Dissertations

"Colloidal Unimolecular Polymer (CUP) particles are a new genre of material formed by self-assembly into spheroidal particles due to the effect of hydrophilic/hydrophobic interactions of the polymer with a change in the solvent. The particle sizes were characterized by means of Dynamic Light Scattering with corrected viscosities instead of water's viscosity. The distribution of particle size agreed well with the distribution of molecular weight proving that the polymer had undergone unimolecular collapse. The rheology study shows the presence of surface water and its significant effect on the rheology. The primary and secondary electroviscous effects were also found to play roles …

Comparative Evaluation Of N-Acetylcysteine And N-Acetylcysteine Amide In Acetaminophen-Induced Oxidative Stress, Ahdab Naeem Khayyat

Masters Theses

"Acetaminophen (APAP) is the most widely used pharmaceutical analgesic-antipyretic agent in the world, but its toxicity is a common cause of drug-induced hepatotoxicity. With APAP toxicity, cellular glutathione (GSH) is depleted. This results in the availability of N-acetyl-p-benzoquinone imine (NAPQI), is a toxic metabolite of APAP that binds to cellular macromolecules, which leads to cell necrosis. N-acetyl cysteine (NAC), a GSH precursor, is the only approved antidote for an acetaminophen overdose. It is a negatively charged molecule that diminishes its penetration into the cells, thereby requiring fairly high doses that increase the severity of side effects. In addition, oral and …

Role Of Nicotine In Oxidative Stress, Rakesh Kacham

Masters Theses

"Nicotine, a major alkaloid, is present in tobacco products as well as in smaller amounts in potatoes, tomatoes, and eggplants. Although it is the addictive compound in cigarettes, nicotine is believed to play a protective role in neurodegenerative disorders such as Parkinson's disease. Researchers have found that the short-term administration of nicotine may help improve the memory process by reducing oxidative stress in the brain. Our studies have shown that, by blocking Fenton's reaction, nicotine is able to inhibit free radical generation, so this research has focused on the antioxidant properties of nicotine. The cell lines of the alveoli, blood …

Part I: Increased Leaching Of Arsenic, Selenium, Molybdenum, And Vanadium From High Calcium Coal Ash Containing Trona Reaction Products. Part Ii: Using Agricultural Byproduct Rice Hull As Biosorbent To Remove And Recover Metal Ions In Water, Yongbo Dan

Masters Theses

"Part I. The trona is being injected to control SO_x emission from coal-fired power plants. The results showed that trona ash leached significantly more As, Se, Mo, and V than the control fly ash did, especially under the natural pH condition. In addition, trona ash had a significantly greater soluble fraction than the control ash. Further investigation indicated that greater amounts of the studied anionic elements in the trona ash were associated with the soluble, trona reaction products. Moreover, the insoluble fraction of the trona ash lost its capability to adsorb these elements under the natural pH condition. The …