jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Numan Gözübenli
Source: Academic Platform Journal of Engineering and Smart Systems (article, 2020-01-12)
Field: Materials Science — Materials Chemistry

Döner (Spin) Kaplama ile İki Boyutlu Polimerik Nanokompozitlerin Geniş Alanlı Üretimleri Bu almann amac, dner-kaplama teknii kullanlarak yksek kristal kalite kolloidal ablonlarn eldesi ve bu ablonlardan retilen nanokompozitlerin retim koullarnn belirlenmesidir. Bu amala, hazrlanan akrilat monomeri ierisine homojen dalm silika kolloidleri kullanarak eitli yzeyler zerine dner Physics ; Molecular biology ; Nuclear chemistry ; Chemistry ; Biology Mesoporous Materials and Catalysis ; Photonic Crystals and Applications ; Block Copolymer Self-Assembly
Authors: Pei-Fei Liu
Source: SPIRE - Sciences Po Institutional REpository (preprint, 2020-09-21)
Field: Chemistry — Organic Chemistry

Synthèse hélicosélective de dioxa[6]hélicènes et design d’organocatalyseurs acides de brønsted P-stéréogènes originaux. Cette thèse est composée de deux parties principales. Premièrement, l'accès synthétique hélicosélectif à une nouvelle série de dioxa[6]hélicènes dioxa configurationnellement stables à partir de précurseurs achiraux simples a été développé. L’hélice est créée et contrôlée au cours d'une réaction domino organocatalysée comprenant une alkylation de Michael suivie d’un couplage C–O, qui fournit les 2-nitrodihydrofuranes chiraux sous forme d’uniques stéréoisomères présentant à la fois une chiralité centrale (deux atomes de carbone stéréogènes) et une chiralité hélicoïdale. Il s’agit du premier cas d'une transformation chimique dans laquelle les chiralités centrales et hélicoïdales sont contrôlées simultanément. Ceci donne accès à des molécules chirales très originales pour la synthèse d'hétérohelicènes optiquement actifs par élimination de HNO2 avec une excellente rétention la chiralité hélicoïdale dans la plupart des cas. Dans une second partie, une nouvelle classe d’organocatalyseurs de type acides de Brønsted a été développée dans laquelle la chiralité est centrée sur l'atome de phosphore. Les acides thiophosphiniques P-stéréogènes chiraux optiquement actifs ont été synthétisés., ce qui ouvre de nouvelles opportunités en l’organocatalyse énantiosélective. Ces nouveaux organocatalyseurs ont notamment été utilisés dans la réaction de Pictet-Spengler et les produits ont été obtenus avec de bons rendements et énantiosélectivité modérée (jusqu'à 47% ee). Cette première étape valide le concept initial mais une optimisation supplémentaire est nécessaire pour atteindre des excès énantiomériques plus élevés et pour rendre ces organocatalyseurs plus généraux. Stereocenter ; Chemistry ; Brønsted–Lowry acid–base theory ; Enantioselective synthesis ; Humanities ; Stereochemistry ; Medicinal chemistry ; Philosophy ; Catalysis ; Organic chemistry Synthesis and Properties of Aromatic Compounds ; Origins and Evolution of Life ; Molecular spectroscopy and chirality
Authors: Tamae Seo | Koji Kubota | Hajime Ito
Source: Institutional Repositories DataBase (IRDB) (article, 2020-06-03)
Field: Chemistry — Physical and Theoretical Chemistry

Selective Mechanochemical Monoarylation of Unbiased Dibromoarenes by in Situ Crystallization Palladium-catalyzed Suzuki-Miyaura cross-coupling reactions of liquid, unbiased dibromoarenes under mechanochemical conditions selectively afford the monoarylated products. The lower reactivity of the crystalline monoarylated products relative to the liquid starting materials should be attributed predominantly to the low diffusion efficiency of the former in the reaction mixture, which results in a selective monoarylation. The present study sheds light on a novel approach using in situ phase transitions in solids to design selective organic transformations that are difficult to achieve via conventional solution-based synthesis. Crystallization ; In situ ; Mechanochemistry ; Reactivity (psychology) ; Phase (matter) ; Diffusion Crystallography and molecular interactions ; Catalytic Cross-Coupling Reactions ; Luminescence and Fluorescent Materials
Authors: Mariza Mone
Source: Chalmers Research (Chalmers University of Technology) (article, 2020-01-01)
Field: Materials Science — Polymers and Plastics

Colors of Life and Optoelectronics: Zinc Porphyrins for Light-Emitting Electrochemical Cells and Organic Photodetectors The field of organic optoelectronics constitutes an interdisciplinary field that covers chemistry, physics, materials science and biology. The technological promises of the organic materials over their inorganic counterparts include a lower production cost and the feasibility to be processed through solution-based techniques on large-area and/or flexible substrates. Among organic optoelectronic devices, two technologies are discussed in this thesis. Those are light emitting electrochemical cells (LECs) and photomultiplication (PM) type organic photodetectors (OPDs). The LEC is a light emitting technology that has attracted a lot of scientific interest due to its simple device architecture and fabrication. A category of LECs that is of high interest, are those LECs consisting of materials emitting near-infrared (NIR) light. This specific field is highly alluring, due to the unique applications NIR light can generate in a wide range of fields from medicine to optical communications. However, organic NIR emitters are inherently of lower efficiency when compared to other wavelengths, thus posing a challenge in material design. Hereof, an attempt was made in the context of this work to design and synthesize emitters that will produce light in the deep NIR region and in a functional LEC. The problem of high aggregation of NIR emitters was tackled by blending with appropriate host materials. On the other side, PM type OPDs aim in sensing and not in the production of light. The characteristic of this special category of OPDs is the possibility of enhancing the received weak signal without the need of external components in the device, like photomultiplier tubes. However, since this specific field is not mature yet, there is not adequate knowledge in material design. Thus, there is a need in discovering the materials that will lead to photomultiplication enabling the construction of more efficient devices in the future. In order to achieve all the accomplishments that will be discussed in this thesis, there was a category of molecules that was the heart of all studies. These molecules, often called as colors of life, due to their importance in many processes occurring in nature were porphyrins. Porphyrins are highly versatile motifs and were the tools that led both into production of deep NIR light but also into improving the detection of weak light. Photodetector ; Optoelectronics ; Materials science ; Context (archaeology) ; Nanotechnology ; Fabrication Conducting polymers and applications ; Organic Electronics and Photovoltaics ; Gas Sensing Nanomaterials and Sensors
Authors: Ruining Wang
Source: eScholarship (California Digital Library) (article, 2020-01-01)
Field: Materials Science — Biomaterials

Multifunctional mesoporous silica nanoparticles for drug and large molecule delivery This thesis involves synthesis, derivatization and biomedical applications of mesoporous silica nanoparticles (MSNs) based delivery systems. Chapter 1 introduces the background of MSNs including the advantages of MSNs, modification on MSNs for multifunctionality; formation mechanism, a typical synthesis condition for MCM-41 and following characterizaitons. In chapter 2 &amp;amp; 3, the synthesis and application of target moiety functionalized MSNs for gene therapy in vitro and in vivo are introduced. Chapters 4, &amp;amp; 5 introduce the relevant studies of utilizing MSN based delivery system for the treatment of infectious disease, from a pharmacokinetic study of moxifloxacin delivered by MSNs via different routes, to the enhanced efficacy of MSN based treatment by materials optimizations via inhalation administration route. Chapter 6 discusses the study of a general synthesis method for pore enlargement in various types of MSNs. In Chapter 7, the design and preparation of a thin film consist of ultra large pore-sized mesoporous silica spheres and polymer template macropores is illustrated. Overall, these chapters demonstrate the successful engineering of mesoporous silica nanoparticles and materials optimization and their enhanced performance in biological applications from in vivo tumor shrinkage by gene delivery to antibiotics delivery for enhanced bacterial killing efficacy in mouse model. Mesoporous silica ; Drug delivery ; Nanotechnology ; Nanoparticle ; Materials science ; Nanocarriers ; In vivo ; Chemistry ; Mesoporous material ; Organic chemistry Nanoparticle-Based Drug Delivery
Authors: Artem Badasyan
Source: RUNG (article, 2020-07-20)
Field: Materials Science — Materials Chemistry

Water reveals non-Arrhenius kinetics in protein folding experiments Statistical theories describe systems in equilibrium, and cannot be used to study kinetics. However, the theo- ries are based on coarse-grained parameters, that include assumptions regarding the underlying kinetics. If such assumptions are incorrect, the theoretical expressions, used to process the experimental data, will not fit. I report on one such case we have met within the application of Zimm-Bragg [1] theory to process folding experiments, and discuss the reasons and consequences. Studies of relaxation phenomena in glass-forming liquids by default account for the shift in temperature by some value, corresponding to the glass formation temperature, .In particular, temperature shift appears in hydrated proteins because of the presence of partially glassy states giving rise to non- Arrhenius relaxation times log τ ~ [2]. A phenomenological approach was suggested by Adam and Gibbs as early as in 1965 to describe the sudden increase of viscosity and the slowing down of the collective modes in super-cooled liquids as the temperature is approaching[3]. The key idea of Adam-Gibbs theory was to consider the supercooled liquid as a set of clusters (cooperatively rearranging regions) of different sizes that change with temperature, giving rise to the shift in re- laxation time. The temperature shift factor is present in many theories describing properties of water. Thus, Truskett and Dill had to include the Adamm-Gibbs temperature shift into their simple analytical model of water to achieve the agreement with experimental data on the tem- perature dependence of self-diffusion coefficient [4]. Later, Schiro and Weik have summarised recent in vitro and in silico experimental results regarding the role of hydration water in the onset of protein structural dy- namics, and have reported the presence of super-Arrhenius relaxation region above the ”protein dynamic transition” temperature [4]. Recently, Mallamace et al have used the Adam-Gibbs theory in their NMR meas- urements of protein folding-unfolding in water [4] and to rationalise the complicated pressure-temperature diagrams in these glass-forming systems. Motivated by the considerations above, and taking into account the relationship between the unimolecular rate of folding in water and the relaxation time 45 , we introduce the tem- perature shift into the formulas used to fit experimental data on hydrated polypeptides. By doing so we resolve the paradox and complete the new method of processing the Circular Dichroism ex- perimental data on protein folding Supercooling ; Relaxation (psychology) ; Arrhenius equation ; Non-equilibrium thermodynamics ; Folding (DSP implementation) ; Viscosity ; Kinetics ; Work (physics) Material Dynamics and Properties ; Protein Structure and Dynamics ; Enzyme Structure and Function
Authors: Saurabh Acharya
Source: Deep Blue (University of Michigan) (article, 2020-01-01)
Field: Materials Science — Materials Chemistry

Fundamental and Applied Electrochemistry for Photonic Applications Photonic devices that selectively transmit or reflect light are highly desirable in a wide variety of applications, including energy harvesting, aesthetic decorations and optical displays. However, most of these high optical-quality devices demonstrated to date involve complex patterns or expensive fabrication processes, which limits high volume production. In comparison, electrochemical methods can be simultaneously performed under mild conditions and with the unique advantage of being applicable to objects of arbitrary shape and size. This dissertation is focused on using two ambient condition approaches to fabricate photonic devices with the capacity for scaling up. First, the electrochemical liquid-liquid-solid (ec-LLS) growth technique is used to grow crystalline semiconductor micro/nanowires at T < 80 C and Ge nanowire-based broadband absorbers on thermally sensitive substrates. The low temperature aspect of ec-LLS makes this process compatible with a wide variety of substrates ranging from metals to semiconductors to conducting polymers. This thesis provides a detailed study on the critical factors affecting ec-LLS crystal growth, and the scope for implementation of this growth method for practical applications is detailed. Additionally, electrical and optical characterization of ec-LLS grown Ge micro/nanowires are presented. Second, electrochemical techniques are used to fabricate angle-insensitive structural color filters by sequential electrodeposition of tri-layer asymmetric metal/dielectric/metal Fabry-Pérot cavities. Additionally, low-power consumption tunable color filters are achieved by employing an electrochemical effect into the structural color design. It is shown that the proposed structures offer advantages over existing colorant-based filters in terms of high efficiency, lifetime and switching stability. The benchtop electrodeposition method utilized avoids any reliance on vacuum systems and ancillary equipment. To have a finer control over the electrodeposition processes explored above, it is imperative to understand electrochemical processes and electron transfer processes at semiconductor/liquid junctions. In the last part of the thesis, theoretical and experimental studies on semiconductor-liquid interfaces using individual ultra-micro electrodes are presented, which test the accuracy of Marcus theory at these interfaces. The intent is to develop methodologies that test the extent that classical Marcus theory describes charge transfer at semiconductor/liquid interfaces, and to afford more reproducible and precise measurements of heterogeneous electron transfer rates than are currently available in the literature. Electrochemistry ; Photonics ; Nanotechnology ; Materials science ; Computer science ; Optoelectronics ; Chemistry ; Electrode ; Physical chemistry Anodic Oxide Films and Nanostructures ; Electrochemical Analysis and Applications ; Conducting polymers and applications
Authors: Huda Usman | Shanna-Leigh Davidson | Nithil H. Manimaran | Jenna Nguyen | Aissatou Kenda Bah | Rishabh Seth | Eric J. Beckman | Tagbo H. R. Niepa
Source: ChemRxiv (preprint, 2020-10-20)
Field: Materials Science — Biomaterials

Design of a Well-Defined Poly(Dimethylsiloxane)-Based Microbial Nanoculture System &lt;p&gt;Organosilanes contain hydrocarbon-like backbones, allowing them to react with silicone-based agents in the presence of a catalyst and polymerize into membranes with tunable transport and mechanical properties. Owing to their high hydrophobicity, Poly(dimethylsiloxane) (PDMS) membranes, and more particularly, Sylgard® 184, have been used for applications including drug delivery, gas separation, and microfluidics fabrication. However, the undefined composition of the material and its ability to leach out uncured oligomers make its functionalization and usage challenging for many biological applications. This article presents the design of a novel culture system generated using PDMS-based membranes to study microbial dynamics. The microbial culture system that is referred to as “nanoculture” serves to encapsulate and grow microbes in semipermeable membranes. The mechanical properties of the membranes are reinforced through osmotic annealing, which enable the nanocultures to withstand high shear stress similar to environmental conditions while maintaining transport properties essential to microbial communication and growth. The present study lays the foundation for a novel microbial culture system that would enable the cultivation of microorganisms in environments other than laboratory conditions.&lt;/p&gt; Membrane ; Silicone ; Drug delivery ; Materials science ; Polymeric membrane ; Nanotechnology ; Semipermeable membrane ; Chemical engineering ; Microfluidics ; Chemistry ; Engineering ; Composite material Electrospun Nanofibers in Biomedical Applications
Authors: Benjamin J. Bridge
Source: Scholarship@Western (Western University) (article, 2020-01-01)
Field: Chemistry — Inorganic Chemistry

Iron(II) Metal-Ligand Cooperative Catalysts for Endo-Selective Intramolecular Hydrofunctionalization Two new cationic Fe(II) PR2NR'2 complexes, [Fe(Cp*)(PR2NPh2)(MeCN)]PF6 (R = cyclohexyl, 3a) and [Fe(Cp*)(PR2NPh2)(MeCN)]PF6 (R = phenyl, 3b), were synthesized and characterized. The catalytic activity for intramolecular hydrofunctionalization was tested using the benchmark substrate 2-ethynylaniline (EA) and both catalysts effectively produced indole (Ind). The selectivity of catalysis was also tested using 2-ethynylbenzyl alcohol (EBA) and both catalysts formed only the endo product isochromene (IC). These complexes represent the first well-defined Fe(II) catalysts that are endo selective for the hydrofunctionalization of alkynes. An Fe(II) vinylidene complex, [Fe(Cp*)(PR2NPh2)(=C=CHPh)]PF6 (R = cyclohexyl, 7), was also characterized that suggests an analogous intermediate is responsible for catalytic selectivity. Catalyst decomposition was also probed and a likely off-cycle deactivation product was identified. On-cycle intermediates were potentially identified and proposed as resting-state species in the catalytic cycle. Preliminary studies were attempted to assess activity and selectivity on a small scope of substrates, but more optimization will be required. Catalysis ; Intramolecular force ; Ligand (biochemistry) ; Chemistry ; Metal ; Combinatorial chemistry ; Stereochemistry ; Receptor ; Biochemistry ; Organic chemistry Asymmetric Hydrogenation and Catalysis ; Catalytic C–H Functionalization Methods ; Cyclopropane Reaction Mechanisms
Authors: Elizabeth Barrios
Source: Journal of International Crisis and Risk Communication Research (article, 2020-01-01)
Field: Materials Science — Materials Chemistry

Integrating Graphene into Polymer Derived Ceramics Towards the Development of New Thermoelectric Materials Radioisotope thermoelectric generators (RTGs) have been an enabling technology for the exploration of deep space since the dawn of the Space Age. Since its first deployment in a meteorological satellite in the late 1960's, RTGs have been used to provide solid-state, maintenance-free power to 27 American spacecraft and scientific instruments. While showing great success in the past, the future usage of thermoelectric devices is limited by the low operating efficiencies and the use of hazardous or expensive materials, limiting the use of thermoelectric technologies to niche applications such as space exploration. Current research efforts that address these disadvantages have focused on the creation of nanostructured materials, where the thermoelectric properties can be finely tuned and quantum mechanics can offer properties not observed in traditional materials. The present work begins to look at the prospects of nanostructured polymer-derived ceramic (PDC) systems for their future use in thermoelectric devices. Such a system could provide not only a lightweight, environmentally friendly alternative to the aerospace industry, but it could also find application on Earth in renewable energy technologies. To begin the process of developing such a polymer-based system for bulk thermoelectric materials, this dissertation has investigated the prospects of utilizing graphene networks encased in a silicon oxycarbide (SiOC) matrix. The effects of graphene content and synthesis route on the resulting material properties of SiOC nanocomposites are explored. The structural, thermal, electrical, and mechanical properties of these systems are presented and discussed. This early-stage research on the development of SiOC ceramics for thermoelectric materials concludes with lessons learned and future directions that can be taken towards the successful development of polymer derived ceramics for thermoelectric applications. Materials science ; Ceramic ; Graphene ; Thermoelectric effect ; Thermoelectric materials ; Nanotechnology ; Engineering physics ; Metallurgy ; Composite material ; Engineering ; Physics ; Thermal conductivity ; Thermodynamics Advanced Thermoelectric Materials and Devices
Authors: Yun Hang Hu | Jessica M. Roberts | Henry R. Kilgore | Amirah S. Mat Lani | Ronald T. Raines | Jennifer M. Schomaker
Source: ChemRxiv (preprint, 2020-06-24)
Field: Chemistry — Organic Chemistry

Triple, Mutually Orthogonal Cycloadditions Through the Design of Electronically Activated SNO-OCTs Interest in mutually exclusive pairs of bioorthogonal labeling reagents continues to drive the design of new compounds capable of fast and predictable reactions. The ability to easily modify heterocyclic strained cyclooctynes containing sulfamate backbones (SNO-OCTs) enables electronic tuning of the relative rates of reactions of SNO-OCTs in cycloadditions with Type I–III dipoles. As opposed to optimizations based on just one specific dipole class, the electrophilicity of the alkynes in SNO-OCTs can be manipulated to achieve divergent reactivities and furnish mutually orthogonal dual ligation systems. Significant rate enhancements for reactions of a difluorinated SNO-OCT derivative compared to the parent scaffold were noted, with the second-order rate constant in cycloadditions with diazoacetamides exceeding 1 M−1 s −1 . Computational and experimental studies were employed to inform the design of triple ligation systems that encompass three orthogonal reactivities. Finally, polar SNO-OCTs are rapidly internalized by mammalian cells and remain functional in the cytosol for live-cell labeling, highlighting their potential for diverse in vitro and in vivo applications. Bioorthogonal chemistry ; Electrophile ; Reagent ; Chemistry ; Combinatorial chemistry ; Nanotechnology ; Materials science ; Organic chemistry ; Catalysis ; Click chemistry Click Chemistry and Applications ; Cyclopropane Reaction Mechanisms