jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Scott Crawford
Source: D-Scholarship@Pitt (University of Pittsburgh) (article, 2019-09-26)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Surface Chemistry-Mediated Photoluminescence of Small Diameter Coinage Metal Nanoparticles From size-dependent luminescence to localized surface plasmon resonances, the optical properties that emerge from materials with nanoscale dimensions have been revolutionary. As nanomaterials get smaller, they approach molecular electronic structures, and this transition from bulk to molecular electronic properties is a subject of far-reaching impact. One class of nanomaterials that exhibit particularly interesting optoelectronic features at this size transition are coinage metal (i.e., group 11 elements copper, silver, and gold) nanoparticles with core diameters between approximately 1 to 3 nm (∼25–200 atoms). Coinage metal nanoparticles can exhibit near-infrared photoluminescence features that are not seen in either their molecular or larger nanoscale counterparts. This emission has been exploited as a probe of electronic behavior at the nanoscale and in applications including biological imaging and sensing. Interestingly, photoluminescence figures of merit including quantum yield, energy, and lifetime are largely independent of particle diameter. Instead, coinage metal nanoparticle emission depends on particle surface chemistry, including both metallic composition and capping ligand architecture. The influence of surface chemistry on emergent optoelectronic phenomena has powerful implications for the study and use of these particles due to the theoretically limitless possible surface ligand architectures and metallic compositions. This dissertation discusses the distinct roles of the ligand binding moiety and substituent structure, which are responsible for the “turn on” and fine-tuning of nanoparticle emission properties, respectively. Specifically, the use of ligand exchange strategies on non-luminescent phosphine-capped gold nanoparticles are used to contrast the impacts of strongly-binding (i.e. thiols and sulfides, Chapter 2), intermediate-binding (alkynes, Chapter 3) and weakly-binding (sulfoxides, Chapter 4) ligands on nanoparticle optoelectronic features. The influence of core parameters on photoluminescence is then probed, including the number of valence electrons in the nanoparticle core (Chapter 5) and the metal composition (i.e. gold, silver, or copper, Chapter 6). This dissertation concludes by discussing how surface-mediated nanoparticle emission may be used for downstream applications, demonstrating efficient energy transfer from emissive gold nanoparticles to pendant ytterbium (Chapter 7). These materials are anticipated be foundational both in understanding the unique transition from molecular to bulk electronic structures and in the development of nanomaterials that leverage this transition. Photoluminescence ; Nanoparticle ; Nanomaterials ; Nanotechnology ; Chemistry ; Ligand (biochemistry) ; Luminescence ; Materials science ; Optoelectronics Gold and Silver Nanoparticles Synthesis and Applications ; Nanocluster Synthesis and Applications
Authors: Steven J. Knauss | Samuel A. Brennan | Mark A. Atwater
Source: MRS Advances (article, 2019-07-01)
Field: Materials Science — Materials Chemistry

In-Situ Formation of Carbon Nanofiber Hybrid Architectures for Functional Devices Materials science ; Nanotechnology ; Carbon nanofiber ; Carbon fibers ; Nanomaterials ; Process engineering ; Carbon nanotube ; Composite material ; Composite number Carbon Nanotubes in Composites ; Graphene research and applications ; Supercapacitor Materials and Fabrication
Authors: Shalmali Hui
Source: International Journal of Chemical and Environmental Sciences (article, 2019-11-01)
Field: Materials Science — Polymers and Plastics

Effect of both Modified &amp; Unmodified Nanosilica on Morphological and Thermal Properties of Model TPE Blend Systems A comparative study between the modified and unmodified nanosilica to fine tune the morphological and thermal properties of a model low-density polyethylene (LDPE) – ethylene vinyl acetate copolymer (EVA) thermoplastic elastomer blend system is explored in this article. The nanosilica particles were melt-blended with the LDPE/EVA system through the variation of the sequence of addition. The blends were compression molded, and their morphological and thermal properties were evaluated. The incorporation of nanosilica particles produced a drastic improvement in thermal stability as compared to the control blend. The morphological studies clearly indicated that modified nanosilica had a homogeneous dispersion in the bi -component polymer matrix leading to strengthening of silica-polymer interface. Interestingly, after modification the sequence did not play a major role in affecting the morphology of this system. Overall, although the properties of the unmodified nanosilica filled blends are strong functions of the sequence of addition, but, interestingly, the properties of the modified nanosilica filled blends do not depend much on the preparation procedure. Materials science ; Low-density polyethylene ; Thermal stability ; Copolymer ; Polymer ; Polymer blend ; Ethylene-vinyl acetate ; Composite material ; Morphology (biology) ; Elastomer ; Thermoplastic elastomer ; Chemical engineering Polymer Nanocomposites and Properties ; Polymer crystallization and properties ; biodegradable polymer synthesis and properties
Authors: Baolin Zhang | Yu Chen | Shisheng Xiong
Source: Journal of Microelectronic Manufacturing (article, 2019-01-01)
Field: Materials Science — Materials Chemistry

Self-assembly of Blended PS-b-P2VP Block Copolymers Directed Self-Assembly (DSA) of block copolymers (BCPs) is a promising technique for sub-10 nm nanofabrication, which is highly compatible with conventional lithography. DSA relies on the microphase separation of block copolymers to form nanostructures of different morphologies. The pitch size of the obtained nanostructure depends largely on the intrinsic properties of BCPs and is usually fixed when BCPs are produced. One effective way of tuning the pitch size of BCPs is by blending BCPs of different molecular weight. In this paper, we have demonstrated the pitch tuning capability by blending the triblock poly (2-vinyl pyridine-b-polystyrene-b-poly 2-vinyl) pyridine (P2VP-b-PS-b-P2VP) with another triblock P2VP-b-PS-b-P2VP or diblock copolymer (PS-b-P2VP) at various volume ratios by solvent annealing. The nanopatterns of blended BCPs after sequential infiltration synthesis (SIS) and plasma etching process, were characterized by scanning electron microscopy. It’s observed that the blended BCPs can form highly ordered lamellar nanostructures of different pitch sizes at different blending ratios. The method of blending BCPs of varying molecular weights greatly extends the functionality of existing BCPs, with the capability of fine-tuning nanopatterning pitch at nanometer resolution. Copolymer ; Block (permutation group theory) ; Polymer science ; Materials science ; Composite material ; Mathematics ; Combinatorics ; Polymer Block Copolymer Self-Assembly ; Advanced Polymer Synthesis and Characterization ; Advanced Battery Materials and Technologies
Authors: Liam Connah | Vincent Truffault | Goran Angelovski
Source: ChemRxiv (preprint, 2019-05-21)
Field: Materials Science — Materials Chemistry

Investigations into the Effects of Linker Length Elongation on the Behaviour of Calcium-responsive MRI Probes Understanding the relationship between chemical structure and the effectiveness of bioresponsive magnetic resonance imaging contrast agents can offer help to identify key components required for the future development of such probes. Here, we report the development and characteristion of two novel monomeric bifunctional chelators, whose paramagnetic metal complexes can serve as calcium-responsive smart contrast agent (SCA). Specifically, relaxometric titrations, luminescence lifetime measurements, NMR studies and NMR diffusion experiments were carried out to assess the behaviour of each system. Overall, our findings demonstrate the impact of subtle changes to the structure of such probes, affecting a range of properties and their coordination behaviour. Through the understanding of such changes, fine tuning of future SCA designs which show optimal changes in relaxivity can be achieved. Bifunctional ; Calcium ; Titration ; Linker ; Chemistry ; Nuclear magnetic resonance ; Materials science ; Computer science ; Physical chemistry ; Biochemistry ; Physics ; Organic chemistry Lanthanide and Transition Metal Complexes ; Advanced MRI Techniques and Applications ; Magnetism in coordination complexes
Authors: Liam Connah | Vincent Truffault | Goran Angelovski
Source: ChemRxiv (preprint, 2019-05-21)
Field: Materials Science — Materials Chemistry

Investigations into the Effects of Linker Length Elongation on the Behaviour of Calcium-responsive MRI Probes Understanding the relationship between chemical structure and the effectiveness of bioresponsive magnetic resonance imaging contrast agents can offer help to identify key components required for the future development of such probes. Here, we report the development and characteristion of two novel monomeric bifunctional chelators, whose paramagnetic metal complexes can serve as calcium-responsive smart contrast agent (SCA). Specifically, relaxometric titrations, luminescence lifetime measurements, NMR studies and NMR diffusion experiments were carried out to assess the behaviour of each system. Overall, our findings demonstrate the impact of subtle changes to the structure of such probes, affecting a range of properties and their coordination behaviour. Through the understanding of such changes, fine tuning of future SCA designs which show optimal changes in relaxivity can be achieved. Bifunctional ; Linker ; Chemistry ; Calcium ; Titration ; Nuclear magnetic resonance ; Computer science ; Physical chemistry ; Biochemistry ; Physics Lanthanide and Transition Metal Complexes ; Advanced MRI Techniques and Applications ; Magnetism in coordination complexes
Authors: Drew Edelberg
Source:  (article, 2019-01-01)
Field: Materials Science — Materials Chemistry

Systems of Transition Metal Dichalcogenides : Controlling Applied Strain and Defect Density With Direct Impact on Material Properties Transition metal dichalcogenides (TMDs) are crystalline layered materials that have significantly impacted the field of condensed matter physics. These materials were the first exfoliatable semiconductors to be discovered after the advent of graphene. The focus of this dissertation is utilizing multiple imaging and characterization techniques to improve and understand the impact of strain and lattice defects in these materials. These inclusions to the lattice, alter the semiconducting performance in controllable ways. A comprehensive study using scanning tunneling spectroscopy (STM), spectroscopy (STS), scanning transmission electron microscopy (STEM), and photoluminescence (PL) in this work will provide a breadth of ways to pinpoint and cross-examine the impact of these factors on these materials. In the first half of this work we focus on the control of lattice defects through two growth processes: chemical vapor transport (CVT) and self-flux. By fine tuning the growth procedure we are both able to determine the intrinsic defects of the material, their electronics, and consistently diminish their density. The second half uses an in-situ strain device to reversibly control and examine the effects of applied strain on transition metal dichalcogenide layers. Utilizing the scanning tunneling microscope to image the lattice, we characterize the change of lattice parameters and observe the formation of strain solitons within the lattice. Measuring these solitons directly we look at the dynamics of a special class of line defects, folds within the top layer of the material, that occur naturally as strain is relieved within the monolayer. With the available imaging techniques and theoretical models we uncover a host of properties of these materials that are only accessible within the high strain regime Transition metal ; Materials science ; Strain (injury) ; Metallurgy ; Chemistry 2D Materials and Applications ; Chalcogenide Semiconductor Thin Films ; ZnO doping and properties
Authors: Fang Chen | Gao Liu
Source: ECS Meeting Abstracts (article, 2019-09-01)
Field: Materials Science — Polymers and Plastics

Electrolyte Additive Effects Observed By Gradient Polarity Solvent Wash The fast evolution of electrical transportation system and smart grid desires advanced energy storage systems. Lithium-ion battery (LIB) is the primary option for energy storage in the global market, but its performance is still subject to improvement. Solid electrolyte interphase (SEI) plays a crucial role in LIB behavior, and electrolyte additives provide a convenient approach for fine-tuning the properties of SEI. It is crucial to obtain detailed structural and chemical information of SEIs and electrolyte soluble byproducts to promote mechanism understanding of the electrolyte additives and formation and function of SEI. Here, we propose to use gradient polarity solvent wash in combination with spectroscopic analysis to characterize both the composition of the electrolyte and layered structure of SEI. A series of model cells with a metal cathode, a lithium anode, and various additives are analyzed to reveal the electrolyte decomposition products in the electrolyte and the SEIs on the electrodes from these test cells. Electrolyte ; Anode ; Cathode ; Solvent ; Chemical engineering ; Battery (electricity) ; Lithium (medication) ; Chemistry ; Interphase ; Energy storage ; Polarity (international relations) ; Decomposition ; Lithium-ion battery ; Materials science ; Electrode ; Inorganic chemistry ; Organic chemistry ; Thermodynamics ; Physical chemistry Conducting polymers and applications ; Fuel Cells and Related Materials
Authors: Yumiao Ma
Source: ChemRxiv (preprint, 2019-12-13)
Field: Chemistry — Organic Chemistry

Toward Thermodynamically Stable Triplet Carbenes In sharp contrast to the widely studied and applied stable singlet carbenes, only several kinetically persistent triplet carbenes have been studied, and thermodynamically stable triplet carbenes are much less developed. With the Gibbs free energy of C-H bond insertion into methane as a probe, DFT calculations were employed to examine a variety of candidate molecules for stable triplet carbenes. Guided by these calculations, some molecules with significant stability against C-H insertion were designed by fine tuning of geometry and electronic structures. These compounds might be potential candidates for experimental development of stable triplet carbenes. Singlet state ; Triplet state ; Chemistry ; Molecule ; Gibbs free energy ; Computational chemistry ; Singlet fission ; Chemical physics ; Physics ; Atomic physics ; Thermodynamics ; Excited state ; Organic chemistry Cyclopropane Reaction Mechanisms ; Chemical Reactions and Mechanisms ; Chemical Reactions and Isotopes
Authors: Stella M. Luo | Kellie A. Stellmach | Stella Ikuzwe | Dennis Cao
Source: ChemRxiv (preprint, 2019-06-07)
Field: Materials Science — Materials Chemistry

Redox-Active Heteroacene Chromophores Derived from a Non-Linear Aromatic Diimide &lt;div&gt;This work describes a three-step chromatography-free protocol for the synthesis of a novel organic materials&lt;/div&gt;&lt;div&gt;building block, dichlorinated mellophanic diimide (MDI), that is shown to undergo nucleophilic substitution&lt;/div&gt;&lt;div&gt;with a variety of ortho disubstituted benzenes to yield a series of chromophores. Furthermore, 1,2,4,5-&lt;/div&gt;&lt;div&gt;tetrasubstituted benzenes can be used to synthesize tetraimide heteropentacene derivatives endcapped by&lt;/div&gt;&lt;div&gt;MDI motifs. The fine-tuning effects of heteroatom identity were investigated by UV-Vis and fluorescence&lt;/div&gt;&lt;div&gt;spectroscopy, cyclic and differential pulse voltammetries, and density functional theory calculations. Oxidation&lt;/div&gt;&lt;div&gt;of diamino MDI derivatives yields di- and tetraimide functionalized azaacenes with significantly lowered LUMO&lt;/div&gt;&lt;div&gt;levels (down to –4.49 eV), narrowed bandgaps (down to 1.81 eV), and high molar absorptivities (up to 84,000&lt;/div&gt;&lt;div&gt;M&lt;sup&gt;–1&lt;/sup&gt; cm&lt;sup&gt;–1&lt;/sup&gt;).&lt;/div&gt; Chemistry ; Chromophore ; HOMO/LUMO ; Diimide ; Redox ; Stereochemistry ; Medicinal chemistry ; Photochemistry ; Molecule ; Organic chemistry Photochromic and Fluorescence Chemistry ; Synthesis and biological activity ; Luminescence and Fluorescent Materials
Authors: Samrat Ghosh | Akinobu Nakada | Maximilian A. Springer | Takahiro Kawaguchi | Katsuaki Suzuki | Hironori Kaji | Igor A. Baburin | Agnieszka Kuc | Thomas Heine | Ryu Abe | Shu Seki
Source: ChemRxiv (preprint, 2019-07-22)
Field: Materials Science — Materials Chemistry

Identification of Prime Factors for Efficient Photocatalytic Hydrogen Evolution of Covalent Organic Frameworks via Molecular Engineering Visible light driven hydrogen (H2) production from water is a promising strategy to convert and store solar energy as chemical energy. Covalent organic frameworks (COFs) are front runners among different classes of organic photocatalyst, owing to their tunable porosity, crystallinity, optical and electronic properties. Photocatalytic activity of COFs depends on numerous factors such as band gap, crystallinity, porosity, exciton migration, charge separation and transport, stability etc. However, it is challenging to fine tune all these factors simultaneously to enhance the photocatalytic activity. Hence, in this report, we have prioritized the key factors for efficient photocatalytic H2 production through structure–property–activity relationship combined with microwave spectroscopy and first–principles calculations. Careful molecular engineering allowed us to tune the light absorption (i.e. band gap), crystallinity, porosity, layer stacking and charge carrier generation and transport of a series of isoreticular COFs. We have assessed how these properties and the interplay between them impact photocatalytic activity of studied COFs. From the structure–property–activity relationship, we found that light absorption and charge carrier generation and transport are the prime factors, which influence the photocatalytic H2 production of COFs in much greater extent than other factors. Photocatalysis ; Crystallinity ; Materials science ; Hydrogen production ; Stacking ; Covalent bond ; Absorption (acoustics) ; Porosity ; Photocatalytic water splitting ; Charge carrier ; Band gap ; Chemical engineering ; Nanotechnology ; Photochemistry ; Hydrogen ; Optoelectronics ; Chemistry ; Water splitting ; Catalysis ; Composite material ; Organic chemistry Covalent Organic Framework Applications ; Advanced Photocatalysis Techniques ; Metal-Organic Frameworks: Synthesis and Applications
Authors: Luke D. Lavis
Source: Biophysical Journal (article, 2019-02-01)
Field: Chemistry — Organic Chemistry

Building Brighter Fluorophores for Advanced Biological Imaging Biomolecule ; Fluorescence ; Biological imaging ; Chemistry ; Quantum yield ; Photobleaching ; Nanotechnology ; Biophysics ; Fluorescence-lifetime imaging microscopy ; Palette (painting) ; Biological system ; Materials science ; Computer science ; Biology Click Chemistry and Applications ; Advanced Fluorescence Microscopy Techniques ; Advanced Biosensing Techniques and Applications
Authors: Aya Samra | Christopher Gulgas
Source: Undergraduate Scholarly Showcase (article, 2019-04-16)
Field: Chemistry — Physical and Theoretical Chemistry

Dehydration of menthol: Development of an undergraduate organic laboratory experiment By Aya Samra, Pre-pharmacy Advisor: Christopher Gulgas Presentation ID: PM_C11 Abstract: Menthol is a naturally occurring molecule containing an alcohol functional group which can be readily dehydrated to form a variety of alkene products. The goals of this project were to (1) customize and fine tune the dehydration procedure and (2) characterize the product mixture using infrared (IR) and nuclear magnetic resonance (NMR) spectroscopies as well as gas chromatography (GC). The reaction was successful in producing a mixture of menthene products which was analyzed to identify major products. The procedure was then adapted to be employed at the microscale level in the organic laboratories at UC Blue Ash. The reaction procedure and characterization methods shall be presented. Menthol ; Chemistry ; Dehydration ; Alkene ; Microscale chemistry ; Organic chemistry ; Alcohol ; Dehydration reaction ; Catalysis Various Chemistry Research Topics ; Analytical Chemistry and Chromatography
Authors: Yumiao Ma
Source: ChemRxiv (preprint, 2019-12-13)
Field: Chemistry — Organic Chemistry

Toward Thermodynamically Stable Triplet Carbenes &lt;p&gt;In sharp contrast to the widely studied and applied stable singlet carbenes, only several kinetically persistent triplet carbenes have been studied, and thermodynamically stable triplet carbenes are much less developed. With the Gibbs free energy of C-H bond insertion into methane as a probe, DFT calculations were employed to examine a variety of candidate molecules for stable triplet carbenes. Guided by these calculations, some molecules with significant stability against C-H insertion were designed by fine tuning of geometry and electronic structures. These compounds might be potential candidates for experimental development of stable triplet carbenes.&lt;/p&gt; Singlet state ; Chemistry ; Triplet state ; Molecule ; Gibbs free energy ; Computational chemistry ; Singlet fission ; Chemical physics ; Atomic physics ; Thermodynamics ; Excited state ; Physics ; Organic chemistry Cyclopropane Reaction Mechanisms ; Chemical Reactions and Mechanisms ; Chemical Reactions and Isotopes
Authors: Wen-Jong Ma | Leng-Wei Huang | Shih‐Chieh Wang | Ján Buša | Natália Tomašovičová | M. Timko | P. Kopčanský | Katarína Šipošová | Chin‐Kun Hu
Source: arXiv (Cornell University) (preprint, 2019-12-29)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Nematic and smectic liquid crystals modeling with stiff and free-joint Lennard-Jones chain molecules Liquid crystals (LCs) composed of mesogens play important roles in various scientific and engineering problems. How a system with many mesogens can enter a LC state is an interesting and important problem. Using stiff and free-joint Lennard-Jones chain molecules as mesogens, we study the conditions under which the mesogens can enter various LC phases. The guideline is to eliminate the unwanted translational orders under a controlled fine-tuning procedure across a sequence of systems. Instead of monitoring the growth of order out of the disorder, we prepare a configuration of high orientation ordering and find out where it relaxes to. Such a procedure begins with a reference system, consisting of short chains of homogeneous soft spheres, in a liquid-vapor coexistence situation, at which the thermodynamic instability triggers a fast spontaneous growing process. By applying a short pulse of auxiliary field to align the dispersedly oriented clusters, followed by reducing the volume and, finally, changing the homogeneous molecules into heterogeneous chains, we are able to obtain a range of systems, including nematic and smectic LCs, at their stable ordered states. The model can be extended to study the influence of nanoparticles or external field on the LC structure. Liquid crystal ; Materials science ; Chemical physics ; Molecule ; Homogeneous ; Biaxial nematic ; Chain (unit) ; Field (mathematics) ; Thermodynamics ; Chemistry ; Organic chemistry ; Physics Liquid Crystal Research Advancements ; Nonlinear Dynamics and Pattern Formation ; Material Dynamics and Properties