Chemistry Commons^™

Hydrophobically Modified Isosorbide Dimethacrylates As Biomaterials For Bisphenol A Free Dental Fillings, Bilal Marie

Dissertations

Amalgam and Bisphenol A glycerolate dimethacrylate (BisGMA) are the main dental filling materials in use today. Because of the negative perception of amalgam and its lower esthetic appeal, as well as the desire to replace the endocrine disruptor Bisphenol A, which is the building block of BisGMA, there has been a critical need to search for safer alternatives to these dental filling materials.

Isosorbide is a sugar-based molecule generally recognized as safe. It has been extensively studied as a replacement to the Bisphenol A core in various materials. However, isosorbide is extremely hygroscopic, and water uptake in dental fillings causes …

Fluorescence Probes For Bioimaging: Synthesis, Photophysical Properties And Applications, Mehrun Nahar Uddin

Dissertations

Fluorescent probes are a vital tool in the study of cell imaging. There are many types of fluorescent probes ranging from inorganic and organic nanoparticles to organic molecules. When used judiciously, they can help provide essential information on cellular structure and function. The introduction of two-photon microscopy has expanded the need for new probes, in particular near-infrared (NIR) absorbing and emitting fluorescent probes. The photochemical and photophysical properties of NIR probes play a crucial role in their effectiveness in cell imaging by both conventional and two-photon excitation (2PE) microscopy. In this research, the synthesis, photophysical properties, and two-photon absorption (2PA) …

Bodipy Based Photodynamic Therapy And Potassium Probes, Xiangshan Liu

Dissertations

Boron dipyrromethene (BODIPY) has become more and more popular in photophysical and biological applications. BODIPY based fluorescence compounds have numerous advantage properties including low toxicity, high absorption extinction coefficients, high fluorescence quantum yields, sharp fluorescence emissions, and resistance to photobleaching. All the good properties lead to the wide applications of BODIPY based compounds. In this research, two different kinds of BODIPY are synthesized. Firstly, BDBrC containing carbazole and BODIPY core is synthesized. Cellular uptake research shows BDBrC can target on lysosome and singlet oxygen generation research result indicates that BDBrC can be used in photodynamic therapy. BDBrC also shows pH-sensitive …

Characterization Of The Ch Addition Product From Meta- And Ortho-Xylene + Ch Reaction And Direct Experimental Observation Of The Tetrabromine Cluster Br4 Using Synchrotron Photoionization Mass Spectrometry, Rory R. Mcclish

Master's Theses

This thesis is centered on the use of a unique gas-phase spectroscopy technique to characterize products and elucidate reaction mechanisms. Experiments were carried out at the Chemical Dynamics Beamline 9.0.2 of the Advanced Light Source located at the Lawrence Berkeley National Laboratory in Berkeley, CA. Computational work was performed on the scientific supercomputer at USF to supplement experimental findings. Chapter 1 contextualizes the work spurred in response to the deleterious interactions of anthropogenic emissions on Earth’s climate. Chapter 2 describes the theoretical manipulations foundational to the experimental design and interpretation. Chapter 3 delves into the physical details of the experimental …

Optical And Chemical Properties Of Fragaria Ananassa And Galena: Potential Photosensitizers In A Natural Dye-Sensitized Solar Cell, Ibukun S Akinsola, Aderemi B Alabi, Coppede Nicola

Tanzania Journal of Science

Dye is one of the major components for high power conversion efficiency in a dye-sensitized solar cell. There are challenges natural dyes encounter, especially with quick degradation of the dye molecules. This work considered mineral dye in comparison with plant dye to address the challenge of degradation of natural plant dyes. The optical properties and functional groups of the two natural dyes were studied in this work. The absorption spectra, the optical band gaps and the absorption coefficients of the dyes were reported and found to be suitable for use as photosensitizers in a dye-sensitized solar cell (DSSC), as they …

Physico-Chemical Properties Of Mechanically Extracted Banana Juice At Different Ripening Stages, Mathayo G Mathias, Lilian D Kaale, Oscar Kibazohi

Tanzania Journal of Science

This paper presents the findings of a study on physico-chemical properties of low viscosity banana juice from five banana cultivars: Pisang Awak (PSA) an ABB genome, Yangambi km5 (YKM5) an AAA genome and cultivars from AAA-EA genome, namely Mbilabile, Ndeshi and Mlonga. Low viscosity banana juice was extracted using improved mechanical method at five ripening stages. The physico-chemical properties significantly varied according to cultivars and ripening stages (p < 0.05). Yields, total soluble solids (TSS), titratable acidity (TA) and pH were in the range of 19.50–74.03%, 7.33–27.64 ºBrix, 0.37–0.76% malic acid equivalent and 4.09–4.70, respectively. Yields decreased in the order of Mbilabile > Ndeshi > Mlonga > YKM5 > PSA whereas the total soluble solids increased as follows Mlonga < Mbilabile < Ndeshi < YKM5 < PSA. Furthermore, ashes and mineral contents decreased with ripening stages whereas the low viscosity banana juice was rich in potassium and magnesium. Finally, the study recommends stage 5 of the ripeness as ideal for producing low viscosity banana juice. Keywords: Mechanical extraction, Banana cultivar, Ripening stage, Tannin, Banana juice.

Effects Of Ripeness And Blending Speed On The Extraction Yield And Physical Chemical Properties Of Low Viscosity Banana Juice, Oscar Kibazohi, Victor V Matabura

Tanzania Journal of Science

Low viscosity banana juice can be extracted from banana by blending and pressing the resulted semi-solid pulp to separate the juice. This juice extraction technology is relatively new and further studies to understand key parameters for juice release is vital for scaling up production and commercialisation. This study, investigated the influence of blending speed and ripeness stage on banana juice yield using two banana cultivars; the East African highland banana (Mbile) and the exotic banana (Pisang awak). Types of sugars and organic acids in the juice were analysed using an HPLC. Changes with ripening of fruit firmness, juice pH and …

Mathematical Characterization Of Biological Control Of Cassava Pests Model, Yidiat O. Aderinto, Faith O. Ibiwoye, Michael O. Oke, Folashade M. Jimoh

Tanzania Journal of Science

Pests are major constraints to the effective growth and development of every crop through their damage, and can be controlled effectively by the use of their natural enemies which is referred to as the biological pest control. In this study, the biological control model of cassava pests through optimal control theory was presented in order to minimize the population of the pests and stabilize the natural enemies population so as not to affect the crop negatively. A mathematical model was formulated via the Lotka-Volterra model, and the model was characterized. The optimality system was established, the equilibrium point with its …

Temperature Effects On The Corrosion Inhibition Of Mild Steel In Sulfuric Acid Solution By Acacia Senegal Gum With Halide Ions, Jovine Emmanuel, Joseph Buchweishaija

Tanzania Journal of Science

The effects of temperature on the inhibitive effect of naturally occurring Acacia senegal gum exudate on the corrosion of mild steel in sulfuric acid was studied between 35 and 70 °C using electrochemical impedance spectroscopy and potentiodynamic polarization methods. Findings showed that Acacia senegal gum exudate decreases the corrosion rate of mild steel. The inhibition efficiency declined with raising temperature above 35 °C. The increase in the corrosion rate with increasing temperature was observed for both uninhibited and inhibited systems. Addition of halide ions to the Acacia senegal gum exudate solution enhanced the corrosion inhibition efficiency because of synergistic effects, …

The Inhibition Activity Of Tert-Butylhydroquinone Towards Corrosion Of Aluminum, Copper And Stainless Steel In Biodiesel Blend B20 Alternative Fuel, Chaza Joumaa, Ibtissam Saad, Ghassan Younes

BAU Journal - Science and Technology

Tert-butylhydroquinone (TBHQ) has been investigated as corrosion inhibitor for aluminum; copper and stainless steel in biodiesel blend B20 by using electrochemical impedance spectroscopy (EIS) method. The results showed that the inhibition efficiency increases with an increase in the concentration of TBHQ but decreases with increasing temperature from 30℃ to 60℃. A maximum inhibition efficiency of about 61.52% for aluminum was recorded for THBQ in biodiesel blend B20 at temperature 30℃ and at a concentration of 4x10^-6 M which is the lowest concentration used compared to the concentrations of TBHQ used for the other metals (copper and stainless steel). Theoretical …

Self-Assembly Of Black Cumin Oil-Based Nanoemulsion On Various Surfactants: A Molecular Dynamics Study, Aulia Fikri Hidayat, Taufik Muhammad Fakih

Makara Journal of Science

Black cumin is commonly used as traditional medicine due to its wide range of pharmacological potential. Black cumin oil (BCO) was often prepared as nanoemulsion to improve its solubility, stability, and bioavailability. This study was conducted to investigate the molecular behavior as well as structural evolution of BCO-surfactant systems during self-assembly micellization using molecular dynamics (MD) simulations. Several BCO constituents and variations of surfactants were employed to model BCO-surfactant systems. 50 ns of MD simulations were performed to elucidate their evolution of structures and physicochemical properties during formation. Results showed that BCO-tween20 and BCO-lecithin were able to form spherical-shaped micelles …

Exploring The Relationships Among Stoichiometric Coefficients, Number Of Transferred Electrons, Mean Oxidation Number Of Carbons, And Oxidative Ratio In Organic Combustion Reactions, Pong Kau Yuen, Cheng Man Diana Lau

Faculty Publications

Combustion reactions, stoichiometry, and redox reactions are some of the basic contents in chemistry curriculum. Although the counting of transferred electrons is critical in redox reactions, assigning mean oxidation number of organic carbons (ONc) is not always easy. Even though the relationship between the oxidative ratio (OR) and ONc is known, the relationship between the number of transferred electrons (Te−) and OR has not been thoroughly studied. The H-atom method has already been developed to balance and deduct organic combustion reactions. It can be used further to help establish the relationships among the stoichiometric coefficients (SC), the number of transferred …

Influence Of Heat Treatment Time On Cathode Material Cr8O21 For Lithium Battery, Jiu-Kang Teng, Qing-Jie Wang, Liang Zhang, Hong-Mei Zhang, Xiao-Tao Chen, Peng Zhang, Jin-Bao Zhao

Journal of Electrochemistry

Chromium oxide (Cr₈O₂₁) cathode material for lithium batteries was synthesized by thermal decomposition of chromium trioxide (CrO₃) at high temperature. The electrochemical properties of chromium oxide depended on the time and temperature during the heat treatment. Pure phase chromium oxide was prepared, and the effects of heat treatment time on the structures and electrochemical properties of Cr₈O₂₁ were systematically studied. The first discharge mechanism of chromium oxide in lithium batteries was explored, and the results were similar to that in lithium-sulfur batteries. The crystal phases and electrochemical properties of the prepared …

Study On The Uniformity Of Microgrooves In Through-Mask Electrochemical Micromachining With Moving Cathode, Li-Qun Du, Yi-Kui Wen, Fa-Long Guan, Ke Zhai, Zuo-Yan Ye, Chao Wang

Journal of Electrochemistry

As a typical surface texture, microgrooves have broad prospects in the fields of mechanical engineering, bio-medicine, new energy and efficient heat dissipation of electronic products. Through-mask electrochemical micromachining (TMEMM) is widely used in the fabrication of micro-structures because of high processing efficiency and no residual stress. However, due to the edge effect of current distribution, there is often a serious dimension discrepancy problem in electrochemical machining of micro-structures. In order to weaken the influence of edge effect on the uniformity of microgrooves, the method that TMEMM with a moving cathode is presented. The current distribution in the electrochemical machining is …

Nitrogen-Sulfur Co-Doped Porous Carbon Preparation And Its Application In Lithium-Sulfur Batteries, Gui-Xiang Zhao, Wail Hafiz Zaki Ahmed, Fu-Liang Zhu

Journal of Electrochemistry

In recent years, lithium-sulfur (Li-S) batteries have been considered as a promising candidate for the next generation of energy storage system due to their ultrahigh theoretical capacity (1675 mAh·g^-1) and energy density (2600 Wh·kg^-1). However, the practical application of Li-S batteries is seriously limited by their insulating nature of sulfur, the shuttle effect of polysulfides (LiPSs), and volume expansion during charging and discharging. To overcome those disadvantages, one of the commonly methods is to infiltrate sulfur into porous conductive carbon framework, such as porous carbon, hollow carbon spheres, graphene, carbon nanotubes and some composites of the …

Formation And Morphological Evolution Of Nanoporous Anodized Iron Oxide Films, Jin-Wei Cao, Nan Gao, Zhao-Qing Gao, Chen Wang, Sheng-Yan Shang, Yun-Peng Wang, Hai-Tao Ma

Journal of Electrochemistry

The preparation of iron oxide films with nanoporous structure by anodization has attracted much attention for its potential applications. However, the formation mechanism of porous structure during anodization is still unclear. In this paper, the composition of anodic current during the formation of nanoporous anodized iron oxide film was analyzed in combination with the current density-potential response (I-V curve) and the derivation of Faraday’s law. The results showed that the anodic current consisted of an ionic current (leading to the migration of ions to form oxide) and an electronic current (leading to the oxygen evolution), and the …

Carbon-Based Nanostructured Materials For Energy And Water Purification Applications, Daniel Nde

Theses and Dissertations

High demand of energy consumption and a decline in available water sources are two critical issues our growing world is facing today. There are urgent needs to develop efficient ways to convert and store renewable energy and to remove contaminants from wastewater to obtain clean water. To solve the energy issue, hydrogen production from water splitting using renewable energy is one of the solutions, which calls for highly efficient water-splitting electrocatalysts. To solve the clean water issue, filtration membranes using graphene-based nanostructures have received increased attention. In the first project of this work, we use two approaches to synthesize the …

Photoelectrochemical Sensing Based On Zr-Mofs For Homocysteine Detection, Wen-Xia Dong, Guang-Ming Wen, Bin Liu, Zhong-Ping Li

Journal of Electrochemistry

Due to the independent form of the light source and detection system, photoelectrochemical (PEC) sensor has the advantages of low background, high sensitivity and simple operation. So far, PEC systems have been widely used in the fields including the actual detection of metal ions, biological antibodies or antigens in environmental pollutants. When the photosensitive material is irradiated by a light source with an energy being equal to or greater than its band gap, electrons (e^-) transition occurs from the valence band to the conduction band, leaving a hole (h⁺), at the same time, the generated electron-hole …

Functional Sulfate Electrolytes Enable The Enhanced Cycling Stability Of Nati2(Po4)3/C Anode Material For Aqueous Sodium-Ion Batteries, Shu-Jin Li, Zhi-Kang Cao, Wen-Kai Wang, Xiao-Han Zhang, Xing-De Xiang

Journal of Electrochemistry

Aqueous sodium-ion batteries show promising application in fields of large-scale storage of intermittent renewable energies owing to the earth-abundant sodium resources and incombustible aqueous electrolytes. Primary factors determining whether they can be commercially utilized are low cost and long lifetime. Among current electrode materials, NASICON-type NaTi₂(PO₄)₃ arouses wide interests as an anode material for aqueous sodium-ion batteries as it offers a high specific capacity, fast Na-transport ability and reasonable working potential, however, suffering from insufficient cycling performance caused by severe dissolution of active materials in traditional aqueous electrolytes. In this work, a functional sulfate electrolyte …

Effect Of Glycol Based Coolant Pollution On Pem Fuel Cells Stack And Recovery Measures, Cong-Yi Zhu, Xiao-Hui Li, Quan-Quan Gan

Journal of Electrochemistry

As the heat conduction medium of fuel cell cooling system, coolant is very important for the thermal management of fuel cell stack. In practical application, coolant leakage into the stack often occurs. Due to the randomness of fault location of components, the location of coolant leakage is uncertain, which may occur on the cathode side or anode side of some or all single cells. The main effects of coolant pollution on fuel cell stack are as follows: the output of open circuit voltage decreases sharply, the consistency of single cells voltage decreases and so on, which seriously affects the normal …

Structure Analysis Of Pemfc Cathode Catalyst Layer, Rui-Qing Wang, Sheng Sui

Journal of Electrochemistry

The sluggish oxygen reduction reaction (ORR) on the cathode of the proton exchange membrane fuel cell (PEMFC) has always been one of the key factors limiting its commercialization. The optimization of the cathode catalytic layer structure plays an important role in improving fuel cell performance and reducing production costs. In this paper, two different catalysts (platinum nanoparticles (Pt-NPs) and platinum nanowires (Pt-NWs)) were prepared by using catalyst coated substrate (CCS) method. By constructing a double-layer catalytic layer structure, we analyzed the effect of different catalytic layer structures by performing a single cell test. The results showed that the dense platinum …

Copper Nanoparticles In-Situ Anchored On Nitrogen-Doped Carbon For High-Efficiency Oxygen Reduction Reaction Electrocatalyst, Hui-Fang Yuan, Yue Zhang, Xing-Wu Zhai, Li-Bing Hu, Gui-Xian Ge, Gang Wang, Feng Yu, Bin Dai

Journal of Electrochemistry

Compared with noble metal platinum (Pt)-based catalysts, inexpensive non-noble metal electrocatalysts have attracted extensive attention for oxygen reduction reaction (ORR). Herein, chitosan as a kind of biomass resource rich in nitrogen and carbon was used to prepare nitrogen-doped carbon (N-C) and N-C in-situ anchored by copper nanoparticles (Cu/N-C). The as-obtained N-C and Cu/N-C nanoparticles were successfully used as non-noble eletrocatalysts tested for ORR. Compared with the N-C, the Cu/N-C showed the high surface area of 607.3 m ²·g^-1 with the mean pore size of 2.5 nm and the pore volume of 0.40 cm³·g^{-1 …}

Cyclic Voltammetric Simulations On Batteries With Porous Electrodes, Xue-Fan Cai, Sheng Sun

Journal of Electrochemistry

Lithium-ion batteries (LIBs) are among the most widely used energy storage devices. Whole-cell modeling and simulations of LIBs can optimize the design of batteries with lower costs and higher speeds. The Pseudo-Two-Dimensional (P2D) electrochemical model is among the most famous whole-cell models and widely applied in LIB simulations. P2D model consists of a series of kinetic equations to model Li⁺/Li diffusion in working/counter electrodes and electrolytes, which are filled in the porous electrodes and separator, and reactions at the interface of electrolyte and active particles. The traditional applications of P2D model, however, are limited to the cases where …

Effect Of Aluminum Alloy Surface Modification On Adhesion Of The Modified Polyurethane Coating And Its Corrosion Protective Performance, Xian-Yin Kuang, Shao-Qiang Jin, Yan-Hui Cao, Yan-Mei Zhang, Shi-Gang Dong, Long-Hui Zhu, Li-Wen Lin, Chang-Jian Lin

Journal of Electrochemistry

The ordinary organic coatings on aluminum alloy usually encounter a problem of low adhesion to the substrate, which results in destruction and failure of the long-term protective performance of the anticorrosion systems. The surface modification of aluminum alloy is able to enhance the adhesion of organic coating on aluminum alloys, and to improve their protective performance. In this work, a combined surface modification of anodic oxidation and mussel adhesion protein/CeO₂/3-aminopropyltriethoxysilane composite film (MCA) was developed on the aluminum alloy. The adhesion of modified polyurethane coated on the treated aluminum alloy and its corrosion protective performance were evaluated comprehensively …

A Nanoscale Shape-Discovery Framework Supporting Systematic Investigations Of Shape-Dependent Biological Effects And Immunomodulation, Wei Zhang, Hender Lopez, Luca Boselli, Paolo Bigini, André Perez-Potti, Zengchun Xie, Valentina Castagnola, Qi Cai, Camila P. Silveira, Joao M. De Araujo, Laura Talamini, Nicolò Panini, Giuseppe Ristagno, Martina B. Violatto, Stéphanie Devineau, Marco P. Monopoli, Mario Salmona, Valeria A. Giannone, Sandra Lara, Kenneth A. Dawson, Yan Yan

Articles

Since it is now possible to make, in a controlled fashion, an almost unlimited variety of nanostructure shapes, it is of increasing interest to understand the forms of biological control that nanoscale shape allows. However, a priori rational investigation of such a vast universe of shapes appears to present intractable fundamental and practical challenges. This has limited the useful systematic investigation of their biological interactions and the development of innovative nanoscale shape-dependent therapies. Here, we introduce a concept of biologically relevant inductive nanoscale shape discovery and evaluation that is ideally suited to, and will ultimately become, a vehicle for machine …

Splashing Of Large Helium Nanodroplets Upon Surface Collisions, Paul Martini, Simon Albertini, Felix Laimer, Miriam Meyer, Michael Gatchell, Olof E. Echt, Fabio Zappa, Paul Scheier

Faculty Publications

In the present work we observe that helium nanodroplets colliding with surfaces can exhibit splashing in a way that is analogous to classical liquids. We use transmission electron microscopy and mass spectrometry to demonstrate that neutral and ionic dopants embedded in the droplets are efficiently backscattered in such events. High abundances of weakly bound He-tagged ions of both polarities indicate a gentle extraction mechanism of these ions from the droplets upon collision with a solid surface. This backscattering process is observed for dopant particles with masses up to 400 kilodaltons, indicating an unexpected mechanism that effectively lowers deposition rates of …

High-Resolution Cryo-Electron Microscopy Structure Of Photosystem Ii From The Mesophilic Cyanobacterium, Synechocystis Sp. Pcc 6803, Christopher J. Gisriel, Jimin Wang, Jinchan Liu, David A. Flesher, Krystle M. Reiss, Hao-Li Huang, Ke R. Yang, William H. Armstrong, M. R. Gunner, Victor S. Batista, Richard J. Debus, Gary W. Brudvig

Publications and Research

Photosystem II (PSII) enables global-scale, light-driven water oxidation. Genetic manipulation of PSII from the mesophilic cyanobacterium Synechocystis sp. PCC 6803 has provided insights into the mechanism of water oxidation; however, the lack of a highresolution structure of oxygen-evolving PSII from this organism has limited the interpretation of biophysical data to models based on structures of thermophilic cyanobacterial PSII. Here, we report the cryo-electron microscopy structure of PSII from Synechocystis sp. PCC 6803 at 1.93-Å resolution. A number of differences are observed relative to thermophilic PSII structures, including the following: the extrinsic subunit PsbQ is maintained, the C terminus of the …

Exploration Of Carbon-Oxygen And Carbon-Nitrogen Bond Formation Utilizing Trichloroacetimidates And Investigations Of New Reactions Mediated By Oxoammonium Salts, Rowan Meador

Dissertations - ALL

Mono-O-alkylated 1,1′-bi-2-naphthols (BINOLs) are often used as the source of chirality for catalysts or ligand systems that are employed in asymmetric organic transformations. However, these BINOLs can be hard to synthesize. The O-alkylation of BINOL can be accomplished with primary and secondary alkyl halides or under Mitsunobu conditions, the yields of these alkylations with tertiary halides or alcohols are very low. A new protocol was developed utilizing trichloroacetamide electrophiles to install bulky groups onto one of the phenolic oxygens. Trichloroacetimidates are also shown to be useful reactions for the synthesis of esters. These reagents proceeded through a symbiotic activation pathway. …

The Phase Behavior Of Ubqln Proteins And Implications For Protein Quality Control, Yiran Yang

Dissertations - ALL

The ubiquitin-proteasome system (UPS) and autophagy are essential pathways for maintaining protein quality control (PQC) in cells. Misfolded proteins and large aggregates are cleared by UPS and autophagy signaled by ubiquitin (Ub) or polyubiquitin (polyUb) chains. Shuttle proteins facilitate cargo transporting by interacting with both ubiquitin and degradation machineries. Previously, our lab discovered that the shuttle protein Ubiquilin-2 (UBQLN2) is recruited to stress granules in cells and undergoes liquid-liquid phase separation (LLPS) in vitro. LLPS is a biophysical process by which proteins separate themselves from the surrounding aqueous solution by forming protein-rich droplets. The overarching goals of this work are …

Formation Of Pyrroloindolines And Alkylation Of N-Heterocycles With Trichloroacetimidates And Synthesis Of Quinoline Based Small Molecule Inhibitors Of Ghrelin O-Acyltransferase (Goat), Bhaskar Joshi

Dissertations - ALL

Pyrroloindolines and related systems are present in a large number of complex natural products. These core structures have generated considerable synthetic interest, as many of the compounds possess challenging, elaborate structures and interesting biological properties. Recently we have focused on using trichloroacetimidates for the synthesis of these fascinating molecules. Trichloroacetimidates can be used an electrophilic source of an alkyl group to form the pyrroloindoline directly from tryptamine derivatives. In this manner trichloroacetimidates provide a flexible solution to accessing highly functionalized pyrroloindoline core structures, needing only a catalytic amount of a Lewis acid to effect the requisite transformations.

Isatin (1H-indol-2,3-dione) based …