jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Hamed J. Jaffer | Hawra`a Sarhan Reshan
Source: Journal of Al-Nahrain University-Science (article, 2018-09-01)
Field: Materials Science — Polymers and Plastics

Synthesis and Characterization of Polymers Bearing Thiourea Moiety and StudyTheir Efficiency in Removing Heavy Metal Ions from Aqueous Solutions Two new polymers were synthesized poly [5-amino-1,3,4-thiadiazol-2-yl (6-methanethioamido-6-oxohexanoyl)carbamodithioate] and Poly[N 1 -((6-aminopyridin-2-yl) carbamothioyl)-N 6thioformyladipamide]. These polymers were characterized by FTIR, 1 H and 13 C NMR spectra. These polymers were tested in removing some heavy metal ions (Cu(II), Cd(II), Zn(II), and Co(II)) from water. The adsorption behavior of these polymers has been studied using different parameters such as, contact time, initial metal ion concentration, weight of the polymer, pH of the solution and temperature. This study reveals that the two polymers have high adsorption capacity for mentioning metal ions. Langmuir, and Freundlich isotherm models were used to fit the experimental data. The experimental data of the adsorption equilibrium correlates well with the isotherm equations. Polymer ; Adsorption ; Metal ions in aqueous solution ; Freundlich equation ; Aqueous solution ; Moiety ; Metal ; Langmuir adsorption model ; Langmuir ; Chemistry ; Polymer chemistry ; Inorganic chemistry ; Materials science ; Organic chemistry Polymer Synthesis and Characterization ; Synthesis and Characterization of Heterocyclic Compounds ; Inorganic and Organometallic Chemistry
Authors: Yu‐Chen Hsu
Source: OakTrust (Texas A&M University Libraries) (article, 2018-05-08)
Field: Chemistry — Inorganic Chemistry

Molecular Sieve Zeolitic-Imidazolate Framework ZIF-90 Thin Films and Membranes for Gas Separation Applications Hydrocarbon separation in the industry is challenging and currently achieved by well-established relative energy intensive and multi-column distillation processes. Even if many promising membrane-based separation technologies were developed to deal with the issues in hydrocarbon separations, we could find limited practical applications by polymeric membranes because of low selectivity and stability in separation process of industry. \n\nZeolitic-imidazolate frameworks (ZIFs) have large potential owing to their well-defined aperture size, robustness, and excellent thermal/chemical stability. Recently, ZIF-90 membranes with effective aperture size ~ 5.0 Å have been investigated to have a large potential to separate C4 hydrocarbons such as n-butane/i-butane mixture which cannot be effectively separated by ZIF-8 membranes. However, there are limited numbers of reports about ZIF-90 membrane fabrication and C4 hydrocarbon separation performance of ZIF-90 membranes.\n \nHerein, we proposed a new method to fabricate thin ZIF-90 membranes (thickness ~ 3 – 5 µm) for C4 hydrocarbon separation via Microwave (MW) assisted seeding of ZIF-8 on alumina supports, solvent-assisted linker exchange, and tertiary growth. Even though the cracks formed after drying, saturated drying technique was applied to reduce the formation of cracks efficiently. In addition, several binary gas permeation measurements have been conducted to obtain the performance of the as-synthesized ZIF-90 membranes. The gas permeation measurement for our targeted C4 hydrocarbons is still waiting until the equipment and C4 hydrocarbon were ready for permeation measurement. Zeolitic imidazolate framework ; Molecular sieve ; Gas separation ; Membrane ; Chemical engineering ; Materials science ; Separation (statistics) ; Imidazolate ; Chemistry ; Metal-organic framework ; Adsorption ; Organic chemistry ; Computer science ; Engineering Metal-Organic Frameworks: Synthesis and Applications
Authors: Annikka Jensen
Source: UNM’s Digital Repository (University of New Mexico) (article, 2018-01-01)
Field: Materials Science — Materials Chemistry

Shape and Surface Chemistry Dictate Cellular Internalization Pathways of Mesoporous Silica Nanoparticles. Advances in the field of nanoparticle biomedical applications have made large strides towards achieving targeted deliver­y of therapeutics and imaging agents. However, less is understood on how the shape of a targeted nanoparticle will alter the level of cellular internalization. The research conducted herein demonstrated that by encasing the bare MSNP with a zwitterionic supported lipid bilayer, referred to as a protocell, the aspect ratio of the MSNP was maintained. However, the non-targeted protocell’s conformal coating drastically diminished the ability of the cell’s active sensory system to recognize the protocell. This finding indicates the cell envokes non-specific macropinocytosis in response to interaction with the silanols present on the bare MSNP surface. Thus, the cell's active shape sensory system is controlled by non-covalent electrostatic and hydrogen bonding interactions with the biomolecular mechanosensitive components of the cell membrane. Additionally, we establish a selective, shape enhanced internalization pathway for the targeted rod shaped protocell AR~1.8-2.3 by conjugation of the SLB with the ligand GE 11, which binds to EGF receptors highly over-expressed on A549 cells. Flow cytometry studies of the effects of chemical inhibitors on nanoparticle cell uptake, along with confocal microscopy colocalization, and TEM studies were performed with A549 cells. The outcomes from these studies showed a shift in the shape-stimulated internalization pathway from non-specific macropinocytosis for anionic bare rod-shaped MSNP to a selective, shape-stimulated, predominantly caveolae-dependent pathway with highly preferential uptake of zwitterionic EGFR-targeted rod shaped protocells in comparison to zwitterionic EGFR-targeted spherical shaped protocells. Internalization ; Nanoparticle ; Mesoporous silica ; Chemistry ; Nanotechnology ; Mesoporous material ; Chemical engineering ; Biophysics ; Materials science ; Biochemistry ; Cell ; Engineering ; Biology Mesoporous Materials and Catalysis
Authors: Pavel Linkov
Source: theses.fr (ABES) (article, 2018-12-19)
Field: Materials Science — Materials Chemistry

Synthesis, physico-chemical and optical characterisation of fluorescent nanocrystals for biomedical applications. Le développement des nanoparticules fluorescentes, appelées quantum dots (QDs) est devenu l'un des domaines les plus prometteurs de la science des matériaux. Dans cette étude une procédure de synthèse de QDs a été mise au point, comprenant la synthèse de noyaux ultra-minces de CdSe, la purification de noyau haute performance, le revêtement central avec une coquille épitaxiale en ZnS. Cette approche a permis d’obtenir des QDs d’une taille de 3,7 nm possédant un rendement quantique supérieur à 70%. Les QDs développés ont été utilisés pour concevoir des conjugués de QDs compacts avec les nouveaux dérivés d'acridine, ayant une affinité élevée pour le G-quadruplex des télomères, ainsi que leur effet inhibiteur sur la télomérase, une cible importante du traitement du cancer. Les résultats de cette étude ouvrent la voie à l'ingénierie de nanosondes multifonctionnelles possédant une meilleure pénétration intracellulaire, une plus forte brillance et une stabilité colloïdale plus importante. Quantum dot ; Fluorescence ; Agrégation ; Atomic force microscopy Quantum Dots Synthesis And Properties ; Carbon and Quantum Dots Applications ; Cancer Research and Treatment
Authors: Antonio Gaetano Ricciardulli
Source: Gutenberg Open Science (article, 2018-01-01)
Field: Materials Science — Polymers and Plastics

Solution-Processed Two-Dimensional Materials for Organic Optoelectronics 97 Seiten Materials science ; Optoelectronics ; Nanotechnology Conducting polymers and applications ; Synthesis and properties of polymers ; Perovskite Materials and Applications
Authors: 一馬 間瀬
Source: Kyushu University Institutional Repository (QIR) (Kyushu University) (article, 2018-03-20)
Field: Materials Science — Materials Chemistry

Development of Triplet-Triplet Annihilation Based Photon Upconversion in Condensed Systems Annihilation ; Photon upconversion ; Photon ; Physics ; Nuclear physics ; Quantum mechanics ; Excitation Luminescence Properties of Advanced Materials ; Radiation Detection and Scintillator Technologies ; Photorefractive and Nonlinear Optics
Authors: Jin Gu Kang
Source: IDEALS (University of Illinois Urbana-Champaign) (article, 2018-12-02)
Field: Materials Science — Materials Chemistry

Thermal, electrical and mechanical properties of three-dimensional functional materials Colloidal assembly is a dynamic phenomenon where the particulates dispersed in fluids, with the size over tens of nms to several μms, form into specific spatial organization resulting from the variations in the surroundings. The general hard sphere colloids with charged surfaces can be self-assembled into the periodic arrays during the drying process of the fluids. These static periodic arrays, namely, colloidal crystals do not possess any dynamic functionalities, but serve as a sacrificial template for the fabrication of various classes of 3D functional materials. On the other hand, some colloids themselves have their own dynamic functionalities, so that they can be directed-assembled in response to external triggering forces. These particles serve as an active element that offers dynamic changes in the properties of the material systems.\nThe inorganic 3D functional meso/nanostructures were developed for the potential uses in thermal management applications using the self-assembled colloidal crystals as the template. Especially, the Fe3O4 was epitaxially grown through the complex 3D colloidal templates, after which the single crystal Fe3O4 3D porous structures were obtained. These materials have the multiple nanosized 3D interfaces to deter the phonon transport, and at the same time consist of the single crystals to enhance the electron transport. Through various kinds of analysis tools, we thoroughly characterized the materials, particularly focusing on the crystallinity, the density, the thermal conductivity, and the electrical conductivity. The epitaxial Fe3O4 nanoporous structures including the pores with 40 nm in diameter were identified to be thermally insulating and electrically conductive at the same time.\nThe dynamically reconfigurable colloidal assembly in the viscoelastic fluids was investigated with the ultimate goals of the energy harvesting. As the first step, two different methods of integrating the colloids into the viscoelastic media were developed. The PNIPAM colloids, which intrinsically possess the thermo-responsive functionality, were synthesized by two kinds of polymerization routes, and then incorporated into the fibrin networks hydrogels using the method developed. The PNIPAM microgels/fibrin networks hydrogel composites demonstrated the reversibly switchable mechanical property, which is multifold jump in the storage modulus due to the strain-stiffening of fibrin networks, in response to the external temperature changes. Thermal ; Materials science ; Physics ; Thermodynamics Thermal properties of materials
Authors: Alex Farnsworth
Source: ScholarsArchive  (Brigham Young University) (article, 2018-01-01)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Nonlinear Optical Characterization of Solids Vibrational Sum Frequency Generation (VSFG) and the similar Second Harmonic Generation (SHG) are both classified as nonlinear optical phenomena, with the hallmark trait being that the input and output frequencies are different. Both of these systems are remarkable tools due to their surface specific nature. Still, there is much that is not known about the response from these systems, especially the nonresonant SFG response. We have worked to better understand SFG signal, specifically the nonresonant temporal profile. We have also collected results that call into question some underlying assumptions about time-based suppression methods when working with single crystal substrates. As an extension of this work we have also investigated the limits of SHG as a possible method for stress testing. Nondestructive testing (NDT) is the assessment of a component to determine its viability of use without damaging the component itself. Early results have shown that SHG has the capability to be used as an NDT platform. SHG sensitivity to surface and interface changes has been shown in mechanical deformation in aerospace grade aluminum, and in chemical changes in naval grade aluminum. SHG signals from a metal surface change as the chemical or physical makeup of the surface changes. Results show that SHG has the potential to be dramatically more sensitive than current methods and allows us to identify the earliest stages of material response to mechanical and chemical stress. Characterization (materials science) ; Nonlinear system ; Computer science ; Environmental science ; Mathematics ; Physics ; Optics Nonlinear Optical Materials Research ; Photonic and Optical Devices ; Semiconductor Lasers and Optical Devices
Authors: Lassi Hällström
Source: Aaltodoc (Aalto University) (article, 2018-02-12)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Simulations and measurements of GaAs-based photoelectrochemical cells The photoelectrochemical cell offers a way to use solar power to efficiently split water into hydrogen and oxygen. A semiconductor electrode is used to generate electrical power from sunlight and drive the hydrogen and oxygen evolution reactions in aqueous environment. The work in this thesis aims to improve the understanding of the dynamics of the semiconductor electrode in a photoelectrochemical cell by implementing a numerical model of the system. The model is used to solve the carrier densities during the operation, when the charge carriers in the semiconductor are not in thermal equilibrium due to the incident radiation generating electron-hole pairs. The simulated results are compared to experimental study of different GaAs-based photoelectrodes.&#13;\n&#13;\nFor the experimental study both p- and n-type GaAs photoelectrodes were fabricated. In addition, a sample with a thin epitaxial n-type layer on a p-type substrate was studied. Chopped light voltammetry and electrochemical impedance spectroscopy measurements were used to characterize the samples. The results show that p-type GaAs is not effective as a photoelectrode due to large overpotential required before any photocurrent was observed. The n--type layer was found to slightly improve the results. The current from the n-type sample was observed to be significantly better, but this is likely to be attributed to dissolving of the sample instead of water splitting reaction. The implementation of the numerical model was successful, but the accuracy of the simulated results leaves room for improvement. The implementation of drift-diffusion model used for the simulation cannot explain all of the measured results, and a more sophisticated model would be required for predictive simulations. Based on the results, key issues are identified and future development ideas suggested. Optoelectronics ; Materials science ; Environmental science ; Computer science Ga2O3 and related materials ; Electron and X-Ray Spectroscopy Techniques ; solar cell performance optimization
Authors: Vladimir Kh. Kozlovskiy
Source: World Journal of Condensed Matter Physics (article, 2018-01-01)
Field: Chemistry — Physical and Theoretical Chemistry

Model of Cubic Cell for Description of Some Phase Transitions in Crystals The purpose of the research is to develop a dynamical theory of phase transitions in crystalline structures, when except for temperature, the pressure is acting. So, the phase diagram temperature-pressure (dimensions) must be constructed. In general case, it is a complicated question, which can be solved for simple models of crystal, as three atomic models, introduced in the work of Frenkel [1]. In this model, three identical atoms are placed on the straight line and interact with the forces, which can be described by the expression, given in the article of Lennard-Jones [2]. Such simple model may have success, when the crystalline structure is simple, which consists of one type of atoms, for example: carbon. The model was generalized to cubic cell model with a moving atom in the inner part of the cell. The rigorous calculation of phase diagram for transition graphite-diamond shows some similarity with results of numerous experimental investigations (which are not discussed here). So, the way of phase diagram calculation may attract attention. Phase diagram ; Simple (philosophy) ; Atom (system on chip) ; Phase transition ; Diagram ; Phase (matter) ; Crystal (programming language) ; Diamond ; Cubic crystal system ; Graphite ; Work (physics) ; Statistical physics ; Materials science ; Condensed matter physics ; Physics ; Thermodynamics ; Quantum mechanics ; Mathematics ; Computer science Advanced Physical and Chemical Molecular Interactions
Authors: Guillaume Paradis
Source:  (article, 2018-01-01)
Field: Materials Science — Materials Chemistry

Étude du mécanisme de croissance du filament bactérien Plusieurs types de bactéries peuvent se déplacer dans leur milieu à l’aide de flagelles rotatifs. Ces flagelles sont composés d’un moteur rotatif ainsi que d’un filament long qui peut atteindre plusieurs fois la longueur du corps (10-15 μm) à l’extérieur de la cellule. Ceux-ci sont composés d’un assemblage de plusieurs milliers de protéines identiques appelées flagelline (FliC). Chaque filament croît par auto-assemblage des unités de FliC à son extrémité extérieure. Chaque FliC doit donc être transportée, partiellement dépliées dans un mince canal à l’intérieur du filament. Au bout du filament se trouve une structure, nommée le cap, composée de 5 protéines FliD essentielles à la polymérisation de la flagelline. Le travail réalisé au cours de cette thèse porte sur deux aspects particuliers de l’assemblage d’un filament. Premièrement, un filament peutil continuer à s’assembler s’il est cassé ? Deuxièmement, quel est le taux de croissance d’un filament et est-ce que ce taux varie avec la longueur du filament ? En utilisant des impulsions laser ultrabrèves, nous avons coupé des filaments marqués d’un fluorophore pour observer s’ils continuaient à s’assembler. Suivant une période de croissance de 2 heures, les filaments étaient marqués de fluorophores différents et observées sous un microscope en épifluorescence. Une souche de Salmonella enterica génétiquement modifiée pour n’exprimer en moyenne qu’un seul filament par cellule a été utilisée. Cette modification assure que chaque filament revisité a bien été coupé auparavant. La même expérience fut aussi réalisée à l’aide d’une souche surexprimant la protéine FliD. En tout, 82 filaments bactériens furent ainsi coupés, puis observés après une période de croissance et aucune reprise de croissance ne fut observée. Ces résultats peuvent sembler surprenants à la lumière de récentes études qui ont rapporté que les filaments continuent de s’assembler lorsqu’ils sont cassés mécaniquement par des forces de cisaillement (”shearing”). En utilisant des marquages de couleurs différentes, nous avons aussi mesurer le taux de croissance du filament en fonction de sa longueur. Nos résultats démontrent que le taux de croissance diminue graduellement avec la longueur, allant de ∼ 4μm/h à 1μm jusqu’à ∼ 1μm/h à 10 μm. Ces résultats contrastent avec le taux constant de 2.3m/3h rapporté récemment dans la littérature. Les expériences décritent dans cette thèse ont donc permis d’élaborer un modèle novateur décrivant le mécanisme de croissance du filament bactérien combinant la simple diffusion avec un mécanisme actif qui introduit les flagellines à la base du filament. Geology Pickering emulsions and particle stabilization ; Enzyme Production and Characterization
Authors: Matthew Caputo
Source: OhioLink ETD Center (Ohio Library and Information Network) (article, 2018-01-01)
Field: Materials Science — Materials Chemistry

4-Dimensional Printing and Characterization of Net-Shaped Porous Parts Made from Magnetic Ni-Mn-Ga Shape Memory Alloy Powders Net (polyhedron) ; Materials science ; Alloy ; Characterization (materials science) ; Metallurgy ; Porosity ; Shape-memory alloy ; Nanotechnology ; Composite material ; Geometry ; Mathematics Shape Memory Alloy Transformations ; Additive Manufacturing and 3D Printing Technologies
Authors: Michael Stolle | Cécile Fradin
Source: bioRxiv (Cold Spring Harbor Laboratory) (preprint, 2018-06-29)
Field: Chemistry — Spectroscopy

Anomalous diffusion in inverted variable-lengthscale fluorescence correlation spectroscopy Abstract Using fluorescence correlation spectroscopy (FCS) to distinguish between different types of diffusion processes is often a perilous undertaking, as the analysis of the resulting autocorrelation data is model-dependant. Two recently introduced strategies, however, can help move towards a model-independent interpretation of FCS experiments: 1) the obtention of correlation data at different length-scales and 2) its inversion to retrieve the mean-squared displacement associated with the process under study. We use computer simulations to examine the signature of several biologically relevant diffusion processes (simple diffusion, continuous-time random walk, caged diffusion, obstructed diffusion, two-state diffusion and diffusing diffusivity) in variable-lengthscale FCS. We show that, when used in concert, lengthscale variation and data inversion permit to identify non-Gaussian processes and, regardless of Gaussianity, to retrieve their mean-squared displacement over several orders of magnitude in time. This makes unbiased discrimination between different classes of diffusion models possible. Anomalous diffusion ; Statistical physics ; Diffusion ; Fluorescence correlation spectroscopy ; Autocorrelation ; Diffusion process ; Random walk ; Mean squared displacement ; Thermal diffusivity ; Gaussian ; Algorithm ; Statistics ; Physics ; Mathematics ; Computer science ; Chemistry ; Optics ; Fluorescence ; Thermodynamics ; Computational chemistry ; Innovation diffusion Diffusion Coefficients in Liquids ; NMR spectroscopy and applications ; Advanced Neuroimaging Techniques and Applications
Authors: Ashish B. George | Kirill S. Korolev
Source: PLoS Computational Biology (preprint, 2018-12-27)
Field: Chemistry — Physical and Theoretical Chemistry

Chirality provides a direct fitness advantage and facilitates intermixing in cellular aggregates Chirality in shape and motility can evolve rapidly in microbes and cancer cells. To determine how chirality affects cell fitness, we developed a model of chiral growth in compact aggregates such as microbial colonies and solid tumors. Our model recapitulates previous experimental findings and shows that mutant cells can invade by increasing their chirality or switching their handedness. The invasion results either in a takeover or stable coexistence between the mutant and the ancestor depending on their relative chirality. For large chiralities, the coexistence is accompanied by strong intermixing between the cells, while spatial segregation occurs otherwise. We show that the competition within the aggregate is mediated by bulges in regions where the cells with different chiralities meet. The two-way coupling between aggregate shape and natural selection is described by the chiral Kardar-Parisi-Zhang equation coupled to the Burgers' equation with multiplicative noise. We solve for the key features of this theory to explain the origin of selection on chirality. Overall, our work suggests that chirality could be an important ecological trait that mediates competition, invasion, and spatial structure in cellular populations. Chirality (physics) ; Mutant ; Competition (biology) ; Coupling (piping) ; Biology ; Biophysics ; Chemical physics ; Physics ; Ecology ; Materials science ; Genetics ; Gene ; Quantum mechanics ; Spontaneous symmetry breaking ; Symmetry breaking thermodynamics and calorimetric analyses ; Photoreceptor and optogenetics research ; Origins and Evolution of Life