Letteratura scientifica selezionata sul tema "One-surface chemistry"
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Articoli di riviste sul tema "One-surface chemistry"
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Liu, Zhangshuan, Liming Fang, Guillaume Delaittre, Yu Ke e Gang Wu. "Heparinized Polyurethane Surface Via a One-Step Photografting Method". Molecules 24, n. 4 (20 febbraio 2019): 758. http://dx.doi.org/10.3390/molecules24040758.
Testo completoAbstract (sommario):
Traditional methods using coupling chemistry for surface grafting of heparin onto polyurethane (PU) are disadvantageous due to their generally low efficiency. In order to overcome this problem, a quick one-step photografting method is proposed here. Three heparin derivatives incorporating 0.21, 0.58, and 0.88 wt% pendant aryl azide groups were immobilized onto PU surfaces, leading to similar grafting densities of 1.07, 1.17, and 1.13 μg/cm2, respectively, yet with increasing densities of anchoring points. The most negatively charged surface and the maximum binding ability towards antithrombin III were found for the heparinized PU with the lowest amount of aryl azide/anchor sites. Furthermore, decreasing the density of anchoring points was found to inhibit platelet adhesion to a larger extent and to prolong plasma recalcification time, prothrombin time, thrombin time, and activated partial thromboplastin time to a larger extent. This was also found to enhance the bioactivity of immobilized heparin from 22.9% for raw heparin to 36.9%. This could be explained by the enhanced molecular mobility of immobilized heparin when it is more loosely anchored to the PU surface, as well as a higher surface charge.
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Brandhuber, Doris, Nicola Huesing, Christina K. Raab, Viktoria Torma e Herwig Peterlik. "Cellular mesoscopically organized silica monoliths with tailored surface chemistry by one-step drying/extraction/surface modification processes". Journal of Materials Chemistry 15, n. 18 (2005): 1801. http://dx.doi.org/10.1039/b417675h.
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Mirkin, Chad A. "Dip-Pen Nanolithography: Automated Fabrication of Custom Multicomponent Sub-100-Nanometer Surface Architectures". MRS Bulletin 26, n. 7 (luglio 2001): 535–38. http://dx.doi.org/10.1557/mrs2001.126.
Testo completoAbstract (sommario):
As physical processes for generating miniaturized structures increase in resolution, the types of scientific questions one can ask and answer become increasingly refined. Indeed, if one had the capability to control surface architecture on the 1–100-nm length scale with reasonable speed and accuracy, one could ask and answer some of the most important questions in science and, in the process, develop technologies that could allow for major advances in surface science, chemistry, biology, and human health. This length scale, which is exceedingly difficult to control, comprises the length scale of much of chemistry and most of biology. Indeed, chemical and biochemical recognition events are essentially sophisticated examples of pattern-recognition processes. Therefore, if one could pattern on this length scale with control over feature size, shape, registration, and composition, one could systematically uncover the secrets of recognition processes involving extraordinarily complex molecules. Arecent invention, dip-pen nanolithography (DPN), may provide access to this type of control over surface architecture and entry into a new realm of structure-versus-function studies for chemists, biologists, physicists, and materials scientists.
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Wang, Zixiao, Feichen Cui, Yang Sui e Jiajun Yan. "Radical chemistry in polymer science: an overview and recent advances". Beilstein Journal of Organic Chemistry 19 (18 ottobre 2023): 1580–603. http://dx.doi.org/10.3762/bjoc.19.116.
Testo completoAbstract (sommario):
Radical chemistry is one of the most important methods used in modern polymer science and industry. Over the past century, new knowledge on radical chemistry has both promoted and been generated from the emergence of polymer synthesis and modification techniques. In this review, we discuss radical chemistry in polymer science from four interconnected aspects. We begin with radical polymerization, the most employed technique for industrial production of polymeric materials, and other polymer synthesis involving a radical process. Post-polymerization modification, including polymer crosslinking and polymer surface modification, is the key process that introduces functionality and practicality to polymeric materials. Radical depolymerization, an efficient approach to destroy polymers, finds applications in two distinct fields, semiconductor industry and environmental protection. Polymer chemistry has largely diverged from organic chemistry with the fine division of modern science but polymer chemists constantly acquire new inspirations from organic chemists. Dialogues on radical chemistry between the two communities will deepen the understanding of the two fields and benefit the humanity.
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Morsbach, Eva, Markus Nesselberger, Jonas Warneke, Philipp Harz, Matthias Arenz, Marcus Bäumer e Sebastian Kunz. "1-Naphthylamine functionalized Pt nanoparticles: electrochemical activity and redox chemistry occurring on one surface". New Journal of Chemistry 39, n. 4 (2015): 2557–64. http://dx.doi.org/10.1039/c4nj02040e.
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Li, Siqi, Songwei Zhang, Dejun Dai e Tao Li. "Facile One-Step Metal–Organic Framework Surface Polymerization Method". Inorganic Chemistry 60, n. 16 (18 giugno 2021): 11750–55. http://dx.doi.org/10.1021/acs.inorgchem.1c00949.
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Shen, Jie, Rui Chen, Jinghong Wang, Ziqing Zhao, Rong Gu, John L. Brash e Hong Chen. "One-step surface modification strategy with composition-tunable microgels: From bactericidal surface to cell-friendly surface". Colloids and Surfaces B: Biointerfaces 212 (aprile 2022): 112372. http://dx.doi.org/10.1016/j.colsurfb.2022.112372.
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Li, Shang, Mi Gu, Sara Garzandat, Xiao Wei Sun e Renaud Bachelot. "8‐2: The micro‐scale adsorption of QDs on select surface by click chemistry". SID Symposium Digest of Technical Papers 55, S1 (aprile 2024): 80–82. http://dx.doi.org/10.1002/sdtp.17001.
Testo completoAbstract (sommario):
QDs’ adsorption on multi‐surface is one of the key points to achieve on‐chip nano‐source. By click chemistry between surface functionalization layer and QDs, QDs were adsorbed on the target surface. This method could achieve small size, stable performance and high efficiency at the same time. Two kinds of surface functionalization material, with similar structure, were used to compare the QDs adsorption ability. DCOOH, the material with click chemistry possibility, exhibit 3‐time stronger adsorption ability comparing the DNO2.
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Machová, Dita, Anna Oberle, Lucie Zárybnická, Jakub Dohnal, Vít Šeda, Jakub Dömény, Veronika Vacenovská et al. "Surface Characteristics of One-Sided Charred Beech Wood". Polymers 13, n. 10 (12 maggio 2021): 1551. http://dx.doi.org/10.3390/polym13101551.
Testo completoAbstract (sommario):
The aim of this paper was to analyze selected properties of beech wood (Fagus sylvatica L.) treated by one-sided surface charring. Specimens were one-side charred with a hot plate using several time-temperature combinations (from 200 to 400 °C). Characteristics such as colour, discoloration, surface roughness, fire resistance, total carbohydrate content at several wood layers and decay resistance were evaluated. Surface charring was applied to the radial and tangential surfaces. Colour measurements showed that the surface of the wood turned grey due to charring. In addition to colour measurements, other experiments showed significant differences between radial and tangential specimens due to their different structures. The higher the temperature used in treating them, the lower the roughness values for radial specimens, while the trend for tangential specimens was the opposite. A smoother surface is more fire resistant, so radial specimens are generally better in this regard. Tangential specimens are more susceptible during preparation to forming cracks that impair flame resistance because a continuous protective densified layer is not formed. The determination of total carbohydrates revealed significant changes at various wood depths after surface charring. These changes were more predictable in radial specimens due to the annual ring orientation, because each layer consisted of a similar earlywood/latewood ratio. Finally, when decay resistance was assessed, weight loss was found to be lower in all specimens than in the references. The results suggest that charring at a particular combination of temperature and time improved the investigated properties of the surface-modified beech.
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Pytskii, Ivan S., Irina V. Minenkova, Elena S. Kuznetsova, Rinad Kh Zalavutdinov, Aleksei V. Uleanov e Aleksei K. Buryak. "Surface chemistry of structural materials subjected to corrosion". Pure and Applied Chemistry 92, n. 8 (25 settembre 2020): 1227–37. http://dx.doi.org/10.1515/pac-2019-1219.
Testo completoAbstract (sommario):
AbstractThe article describes a comprehensive mass spectrometric approach to the study of surfaces of structural materials. The combined use of thermal desorption mass spectrometry, gas and liquid chromatography, and laser desorption/ionization mass spectrometry (LDI) to provide information about the surface and surface layers of materials is proposed. The suggested method allows one to determine the thermodynamic characteristics of compounds and surface contaminants adsorbed on surfaces, as well as surface layers, to determine the composition of volatile and non-volatile contaminants on the surface, and to determine the nature of the distribution over the surface of these compounds. The method allows to obtain the most complete information about the surface condition and can be used to predict the life of structural materials.
Tesi sul tema "One-surface chemistry"
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Christensen, Dana James II. "Composition Effects on Sheen and Spread Rate of an Interior Flat, One Coat Latex Paint Formulation". DigitalCommons@CalPoly, 2015. https://digitalcommons.calpoly.edu/theses/1489.
Testo completoAbstract (sommario):
Interior flat, white latex paint is a common coating applied to walls around the world. Development of a coating with one coat hide capability is a pinnacle achievement for paint formulators as it has the potential to save consumers both time and money. One coat paints already exist on the market, but they are limited in color, coverage, and often have many disclaimers. Work done was part of a project initiated by ChemoursTM Titanium Technologies.
The goal of the project presented in this article was to create an interior flat, white latex paint that yields a spread rate of greater than 400 ft2/gal., which is advertised by many below critical pigment volume concentration (CPVC) commercial paints. In order to achieve this goal, an above CPVC paint with a high TiO2 content was created and continuously improved. Improvement of the formulation involved numerous experimental variations including adjustments to the hydroxyethylcellulose (HEC) molecular weight, dispersant chemistry, latex chemistry, TiO2 concentration, extender package, and rheology modifier type. The sheen value, relative light scattering, and spread rate were the main measurements conducted in order to judge formulation improvement.
Complications with the spread rate procedure forced its adaptation in order to collect less variable data with the high density, shear thinning formulations. It was found that shorter opacity charts yielded more precise spread rate data than the longer opacity charts. An attempt at correlating rheology with sheen development resulted in the conclusion that the pigment and extender particle package is the greatest driving factor behind sheen reduction. The rheology modifier type and dispersant chemistry did not affect the flatness of the paint nearly as much. A Keyence VR-3000 series One-Shot 3D Measuring Macroscope was used to show that surface roughness does not directly correlate to the sheen value when a number of flat paints with different sheens were analyzed.
This project is an ongoing effort and the information contained in this document will substantially help future development.
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Qu, Haiou. "Surface Functionalized Water-Dispersible Magnetite Nanoparticles: Preparation, Characterization and the Studies of Their Bioapplications". ScholarWorks@UNO, 2012. http://scholarworks.uno.edu/td/1536.
Testo completoAbstract (sommario):
Iron oxide magnetic nanoparticle synthesis and their surface functionalization hold a crucial position in the design and fabrication of functional materials for a variety of biomedical applications. Non-uniform nanoparticles with poor crystallinity, prepared by conventional methods, have only limited value in biological areas. Large scale synthesis methods that are able to produce high quality, mono-dispersed iron oxide nanoparticles using low cost and environment friendly chemicals are highly desirable. Following synthesis, appropriate surface functionalization is necessary to direct the dispersibility of nanoparticles in aqueous solution in order to provide them with acceptable colloidal stability against the ion strength and many biomolecules that nanoparticles may encounter under physiological conditions. Poorly stabilized nanoparticles that easily aggregate and form large size agglomerates would be quickly cleared by the liver and other organs and are not suitable for clinical purposes. Additionally, many interesting functionalities such as fluorescence, targeting and anti-cancer properties can be immobilized onto the surface of iron oxide magnetic nanoparticles during the surface functionalization process so as to build multifunctional platforms for disease diagnosis and treatment.
Polyol method can be an effective way to prepare magnetite nanoparticles that are suitable for biological applications. In a polyol system, selected surface functionalities were introduced to the nanoparticle surface via a hot injection technique. The morphology, uniformity, crystallinity and magnetic properties were examined to understand the effect of different ligand molecules on the final product. Their surface chemistry, colloidal properties and surface reactivity were also studied to evaluate their practicability in different applications.
A high efficiency in-situ method for the preparation of magnetite nanoparticles attached to silica nanospheres was also developed in a polyol system. This approach eliminates several time-consuming processing steps that are in the conventional fabrication route and directly produces water-stable magnetite-silica hybrid materials with surface availability for subsequent modifications.
In addition to polyalcohol, the potential of polyamine in the preparation of water-soluble magnetite nanoparticles with amine surface functionalities was also evaluated. And it is suggested that polyamine acts as solvent, stabilizing agent and reducing agent simultaneously during the synthesis. The characterization of polyamine coated nanoparticles, their surface functionalization, and subsequent application for bioseparation and drug delivery were reported.
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Liu, Kai. "Theoretical Characterization of Optical Processes in Modecular Complexes". Doctoral thesis, Stockholm : Bioteknologi, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4629.
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Hamadeh, Ali. "Supramolecular networks and on-surface chemical reactions studied by STM under UHV conditions". Electronic Thesis or Diss., Bourgogne Franche-Comté, 2024. http://www.theses.fr/2024UBFCD027.
Testo completoAbstract (sommario):
Le travail présenté dans cette thèse est centré sur l'exploration des réseaux supramoléculaires et des réactions chimiques en surface sur diverses surfaces solides, en examinant des cas jusqu'alors inexplorés afin d'enrichir les connaissances dans ce domaine. La principale méthode utilisée pour étudier les phénomènes chimiques de surface est la microscopie à effet tunnel, réalisée sous ultra-haut-vide. Le premier chapitre fait un état de l'art en mettant en lumière les principes fondamentaux des réactions chimiques sur surface à travers quelques travaux illustratifs de la littérature. Le deuxième chapitre présente les techniques expérimentales et les équipements utilisés pour réaliser et surveiller les expériences sous UHV. De plus, je donne une brève présentation des surfaces utilisées et les différentes techniques de caractérisation employées pour mener nos expériences. La première partie du chapitre III se concentre sur l'utilisation de la surface Si(111)-7x7 sous UHV, pour promouvoir la dissociation des molécules inertes de N2 par collision à température ambiante et à basse pression. La seconde partie décrira l'exposition de l'hydrogène atomique sur la surface Si(111)-7x7 sur laquelle des atomes d’azote sont adsorbés. Le chapitre IV se focalise sur l'expansion des monocouches en multicouches bien ordonnées pour améliorer la fonctionnalité et la complexité des auto-assemblages. Dans cette étude, nous présentons l'évolution de la conformation moléculaire des réseaux supramoléculaires en 2D à 3D adsorbés sur une surface de HOPG. Le cinquième chapitre s'intéresse à la comparaison des processus de polymérisation en surface induits par des méthodes thermiques et photochimiques sur Au(111) en utilisant quatre blocs de construction moléculaires distincts. Le dernier chapitre résume les résultats de l'ensemble des travaux de thèse et présente des perspectives pour des travaux futurs dans ce domaineThe work in this thesis is focused on exploring supramolecular networks and on-surface chemical reactions on various solid surfaces, examining previously unstudied cases to enhance the field's knowledge base. The primary method employed to investigate surface chemical phenomena is scanning tunneling microscopy, conducted under ultra-high vacuum environment. The first chapter reviews the state-of-the-art by highlighting the basic keys of on-surface chemical reactions through some illustrative works from the literature. The second chapter represents the experimental techniques and equipment that are used for performing and monitoring experiments under UHV. As well, we give a brief presentation of used surfaces concerning their crystalline structures and the different used characterization techniques to conduct our experiments. Chapter III in the first part concentrates on the usage of highly reactive reconstructed Si(111)-7x7 surface, under UHV, to promote a facile dissociation of inert N2 molecules upon soft collision at room temperature and low gas pressure. The second part will be depicted to promote the exposure of atomic hydrogen over the N-adsorbed Si(111)-7x7 surface. Chapter IV focuses on the expansion of monolayers to well-ordered multilayers to enhance the functionality and complexity of self-assemblies. In this study, we present the evolution of molecular conformation from 2D to 3D supramolecular networks adsorbed onto an HOPG surface. The fifth chapter will delve into comparing the on-surface polymerization processes induced by thermal and photochemical methods on Au(111) using four distinct molecular building blocks. The last chapter summarizes the results of the whole thesis work and presents perspectives for future related work
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Hill, Gavin T. H. "The preparation and testing of novel biodegradable surfactants using poly(lactic acid) as the backbone, by a one-step ring opening polymerisation reaction". Thesis, University of St Andrews, 2009. http://hdl.handle.net/10023/746.
Testo completoAbstract (sommario):
A review of the chemistry of poly(lactic acid) was carried out with a focus on techniques and applications of PLA polymer and copolymers with reference to some of the work that has been accomplished over the last 20 years or so. A review of the characterisation techniques used to analyse PLA polymers and copolymers was also carried out giving reference to the equipment and methods used herein. An investigation into the potential of PLA as the hydrophilic portion of a polymeric surfactant was carried out. To develop PLA based surfactants, the ring opening polymerisation of lactide was carried out in a melt in the presence of a long chain alcohol (C₇ to C₂₀) or diol (C₄ & C₆) to produce AB or ABA type polymers that follow the traditional surfactant template. Stannous octanoate and 4-dimethylaminopyridine were typically used as catalysts due to their high activity and relative cheapness. PLA only shows good hydrophilicity with up to 12 lactic acid units in the chain. Above this the electrostatic interactions between polymer chains reduced water solubility. It was also noted that D,L-lactide produced more water soluble polymers (syndiotactic) than the enantiomerically pure L-lactide (isotactic polymer chains). An investigation of the hydrophobic properties of PLA was carried out to evaluate their usefulness for other biodegradable surfactant applications. To this end an investigation of sugars as the hydrophilic portion of the molecule was carried out. Due to problems with solubilising sugars, they were deemed unsuitable for use as initiatiors within the scope of this research. Choline chloride was then investigated as a potential hydrophilic initiator and indeed has produced some of the most water soluble of PLA polymers. Choline chloride presented several challenges as an initiator, its high melting point resulted in polar solvents such as t-butanol being employed. Alternatively, more success was achieved by preparation of a choline chloride eutectic mixture prior to the polymerisation. It was discovered that a choline chloride/urea eutectic mixture was capable of self initiation, thus required no further addition of catalyst, this result shows a potential step forward in PLA green chemistry. A final investigation into producing surface-active PLA in a one-pot process that required only a hydroxycarboxylate initiator was carried out. The production of PLA sodium or potassium salts was carried out in a melt polymerisation and the results show some promise. Initiators that have been employed include a range of a, b and g-hydroxycarboxylic acids. These work through tautomerisation to the alkoxide, which then initiates a living type polymerisation of lactide to produce surface-active polymers. As well as the synthesis of these polymers some analysis of the physical and aqueous properties of these materials was carried out. PLA sodium salts were shown to have reasonable surfactant ability (~45 mNm⁻¹) and low CMC values of around 5x10⁻⁹ mol cm⁻³. They were also shown to have some properties as emulsifiers, and in some cases showed non-Newtonian fluid behaviour such as shear-thinning (thixotropy) and shear-thickening (dilatant). The thermal characteristics of the polymers such as T[subscript]g and stability were assessed as well as their ability to retain water.
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Chen, Haoxin. "Development and Application of A SERS Needle for One-step Multi-phase Analysis". 2018. https://scholarworks.umass.edu/masters_theses_2/713.
Testo completoAbstract (sommario):
Surface-enhanced Raman spectroscopy (SERS) is an emerging and sensitive technique in food analysis providing advantages of rapid detection, simple sample preparation and on-site detection capability over GC and LC methods. Most SERS applications focus on detecting trace amount of analyte in liquid as an alternative approach to HPLC. Herein, we invented an innovative SERS-active needle which is composed with an injection needle and a gold-nanoparticles coated fiber inside the injection needle. The gold nanoparticles-coated fiber was fabricated by reducing gold (III) on a chemically etched stainless wire. The SERS needle can be used to insert into the headspace and liquid sample for simultaneous multiphase sample detection, or a soft tissue like a tomato fruit to detect the analyte inside of the tissue with minimum invasion. Using this needle, we can detect as low as 5 ppb of fonofos in the headspace of water and apple juice samples, compared with the dip method, which cannot detect lower than 10 ppb in water and 50 ppb in apple juice. The SERS needle was also applied in real time pesticide translocation study to monitor internalized thiabendazole in tomato fruit after root uptake. The SERS needle detected thiabendazole inside tomato fruits 30 days after the pesticide exposure in a hydroponic planting environment. Moreover, realizing the advantage of detecting volatile components in the headspace of food sample, we applied the SERS needle in a ground beef spoilage study to detect the spoilage biomarkers in the headspace of the raw beef. As a result, the SERS needle detected volatile spoilage compounds produced by bacteria Lactobacillus. Overall, this invention opens a new field of SERS strategy for broad analytical applications.
Libri sul tema "One-surface chemistry"
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Soghier, Lamia, Katherine Pham e Sara Rooney, a cura di. Reference Range Values for Pediatric Care. American Academy of Pediatrics, 2014. http://dx.doi.org/10.1542/9781581108545.
Testo completoAbstract (sommario):
Here’s the one place to look for normal values and related need-to-know data! Now you no longer have to search through multiple resources for reference ranges and other critical values you need to optimize patient assessment and management. The new Reference Range Values for Pediatric Care brings all the most vital range data - plus diverse clinical evaluation and calculation tools - all together in one concise, compact handbook. Indispensable pediatric reference ranges - right at your fingertips Custom-designed for today’s busy practitioners, this quick-access resource provides commonly used ranges and values spanning birth through adolescence. Data needed for management of preterm newborns and other neonates is highlighted throughout. Look here for practice-focused help with: - Blood pressure ranges - Body surface area calculation - Bone age metrics - Hematology values - Cerebrospinal fluid values - Lymphocyte subset counts - Clinical chemistry ranges - Thyroid function - Umbilical vein and artery catheterization measurements - Caloric intake values - And more! Also includes assessment and management tools you’ll use again and again Save time and simplify clinical problem-solving with a full set of easy-to-use tools from the AAP and other authoritative sources: - APGAR and Ballard newborn screening - Growth charts - Metric conversion tables - Pain scales - Blood pressure nomograms - Hyperbilirubinemia nomograms - Enternal formulas - GIR calculators - AAP immunization schedules - AAP periodicity schedule Drug administration and monitoring guidelines The handbook includes must-know basics on commonly used antibiotics and antiseizure medications - complete with recommended dosages and serum target levels.
Capitoli di libri sul tema "One-surface chemistry"
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Schöllkopf, Wieland. "Grating Diffraction of Molecular Beams: Present Day Implementations of Otto Stern’s Concept". In Molecular Beams in Physics and Chemistry, 575–93. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-63963-1_25.
Testo completoAbstract (sommario):
AbstractWhen Otto Stern embarked on molecular-beam experiments in his new lab at Hamburg University a century ago, one of his interests was to demonstrate the wave-nature of atoms and molecules that had been predicted shortly before by Louis de Broglie. As the effects of diffraction and interference provide conclusive evidence for wave-type behavior, Otto Stern and his coworkers conceived two matter-wave diffraction experiments employing their innovative molecular-beam method. The first concept assumed the molecular ray to coherently scatter off a plane ruled grating at grazing incidence conditions, while the second one was based on the coherent scattering from a cleaved crystal surface. The latter concept allowed Stern and his associates to demonstrate the wave behavior of atoms and molecules and to validate de Broglie’s formula. The former experiment, however, fell short of providing evidence for diffraction of matter waves. It was not until 2007 that the grating diffraction experiment was retried with a modern molecular-beam apparatus. Fully resolved matter-wave diffraction patterns were observed, confirming the viability of Otto Stern’s experimental concept. The correct explanation of the experiment accounts for quantum reflection, another wave effect incompatible with the particle picture, which was not foreseen by Stern and his contemporaries.
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Kakkar, Harjasnoor, Berta Martínez-Bachs e Albert Rimola. "An Ab Initio Computational Study of Binding Energies of Interstellar Complex Organic Molecules on Crystalline Water Ice Surface Models". In Computational Science and Its Applications – ICCSA 2022 Workshops, 281–92. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-10562-3_21.
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AbstractThe interstellar medium is extremely heterogeneous in terms of physical environments and chemical composition. Spectroscopic observations in the recent decades have revealed the presence of gaseous material and dust grains covered in ices predominantly of water in interstellar clouds, the interplay of which may elucidate the existence of more than 250 molecular species. Of these species of varied complexity, several terrestrial carbon-containing compounds have been discovered, known as interstellar complex organic molecules (iCOMs) in the astrochemical argot. In order to investigate the formation of iCOMs, it is crucial to explore gas-grain chemistry and in this regard, one of the fundamental parameters is the binding energy (BE), which is an essential input in astrochemical models. In this work, the BEs of 13 iCOMs on a crystalline H2O-ice surface have been computed by means of quantum chemical periodic calculations. The hybrid B3LYP-D3 DFT method was used for the geometry optimizations of the adsorbate/ice systems and for computing the BEs. Furthermore, to refine the BE values, an ONIOM2-like approximation has been employed to obtain them at CCSD(T), which correlate well with those obtained at B3LYP-D3. Additionally, aiming to lower the computational cost, structural optimizations were carried out using the HF-3c level of theory, followed by single point energy calculations at B3LYP-D3 in order to obtain BE values comparable to the full DFT treatment.
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Spruell, Jason M. "A One-Pot Synthesis of Constitutionally Unsymmetrical Rotaxanes Using Sequential Cu(I)-Catalyzed Azide–Alkyne Cycloadditions". In The Power of Click Chemistry for Molecular Machines and Surface Patterning, 35–51. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-9647-3_3.
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Law, D. W., C. Gunasekara e S. Setunge. "Use of Brown Coal Ash as a Replacement of Cement in Concrete Masonry Bricks". In Lecture Notes in Civil Engineering, 23–25. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-3330-3_4.
Testo completoAbstract (sommario):
AbstractPortland cement production is not regarded as environmentally friendly, because of its associated high carbon emissions, which are responsible for 5% of global emissions. An alternative is to substitute fly ash for Portland cement. Australia has an abundance of brown coal fly ash, as it is the main source of primary energy in the State of Victoria. Currently, the majority of this material is stored in landfills and currently there is no commercial use for it in the cement industry because brown coal fly ash cannot be used as a direct replacement material for Portland cement due to the high sulfur and calcium content and low aluminosilicate content. However, the potential exists to use brown coal fly ash as a geopolymeric material, but there remains a significant amount of research needed to be conducted. One possible application is the production of geopolymer concrete bricks. A research project was undertaken to investigate the use of brown coal fly ash from Latrobe Valley power stations in the manufacture of geopolymer masonry bricks. The research developed a detailed understanding of the fundamental chemistry behind the activation of the brown coal fly ash and the reaction mechanisms involved to enable the development of brown coal fly ash geopolymer concrete bricks. The research identified suitable manufacturing techniques to investigate relationships between compressive strength and processing parameters and to understand the reaction kinetics and microstructural developments. The first phase of the research determined the physical, chemical, and mineralogical properties of the Loy Yang and Yallourn fly ash samples to produce a 100% fly ash-based geopolymer mortar. Optimization of the Loy Yang and Yallourn geopolymer mortars was conducted to identify the chemical properties that were influential in the production of satisfactory geopolymer strength. The Loy Yang mortars were able to produce characteristic compressive strengths acceptable in load-bearing bricks (15 MPa), whereas the Yallourn mortars produced characteristic compressive strengths only acceptable as non-load-bearing bricks (5 MPa). The second phase of the research transposed the optimal geopolymer mortar mix designs into optimal geopolymer concrete mix designs while merging the mix design with the optimal Adbri Masonry (commercial partner) concrete brick mix design. The reference mix designs allowed for optimization of both the Loy Yang and Yallourn geopolymer concrete mix designs, with the Loy Yang mix requiring increased water content because the original mix design was deemed to be too dry. The key factors that influenced the compressive strength of the geopolymer mortars and concrete were identified. The amorphous content was considered a vital aspect during the initial reaction process of the fly ash geopolymers. The amount of unburnt carbon content contained in the fly ash can hinder the reactive process, and ultimately, the compressive strength because unburnt carbon can absorb the activating solution, thus reducing the particle to liquid interaction ratio in conjunction with lowering workability. Also, fly ash with a higher surface area showed lower flowability than fly ash with a smaller surface area. It was identified that higher quantity of fly ash particles <45 microns increased reactivity whereas primarily angular-shaped fly ash suffered from reduced workability. The optimal range of workability lay between the 110–150 mm slump, which corresponded with higher strength displayed for each respective precursor fly ash. Higher quantities of aluminum incorporated into the silicate matrix during the reaction process led to improved compressive strengths, illustrated by the formation of reactive aluminosilicate bonds in the range of 800–1000 cm–1 after geopolymerization, which is evidence of a high degree of reaction. In addition, a more negative fly ash zeta potential of the ash was identified as improving the initial deprotonation and overall reactivity of the geopolymer, whereas a less negative zeta potential of the mortar led to increased agglomeration and improved gel development. Following geopolymerization, increases in the quantity of quartz and decreases in moganite correlated with improved compressive strength of the geopolymers. Overall, Loy Yang geopolymers performed better, primarily due to the higher aluminosilicate content than its Yallourn counterpart. The final step was to transition the optimal geopolymer concrete mix designs to producing commercially acceptable bricks. The results showed that the structural integrity of the specimens was reduced in larger batches, indicating that reactivity was reduced, as was compressive strength. It was identified that there was a relationship between heat transfer, curing regimen and structural integrity in a large-volume geopolymer brick application. Geopolymer bricks were successfully produced from the Loy Yang fly ash, which achieved 15 MPa, suitable for application as a structural brick. Further research is required to understand the relationship between the properties of the fly ash, mixing parameters, curing procedures and the overall process of brown coal geopolymer concrete brick application. In particular, optimizing the production process with regard to reducing the curing temperature to ≤80 °C from the current 120 °C and the use of a one-part solid activator to replace the current liquid activator combination of sodium hydroxide and sodium silicate.
5
McCash, Elaine M. "Surface reactions and reactivity". In Surface Chemistry. Oxford University Press, 2001. http://dx.doi.org/10.1093/hesc/9780198503286.003.0004.
Testo completoAbstract (sommario):
This chapter focuses on surface reactions and reactivity, starting with an explanation of transition state theory. One of the major motivations for studying surface reactions has been to apply the knowledge to the field of catalysis. However, studies of surface reactions are also highly important in fields other than catalysis. In particular, two of the most important are the semiconductor industry and environmental chemistry, where the study of heterogeneous processes in the atmosphere has proved enormously valuable. The chapter details the mechanisms of surface reactions, discussing single molecular species and reactions involving more than one. It also looks at surface photochemistry.
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Shchukin, Eugene D., Alexandr V. Pertsov, Elena A. Amelina e Andrei S. Zelenev. "Surface Phenomena and the Structure of Interfaces in One-Component Systems". In Colloid and Surface Chemistry, 1–63. Elsevier, 2001. http://dx.doi.org/10.1016/s1383-7303(01)80003-x.
Testo completo
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McCash, Elaine M. "Ultrathin films and interfaces". In Surface Chemistry. Oxford University Press, 2001. http://dx.doi.org/10.1093/hesc/9780198503286.003.0005.
Testo completoAbstract (sommario):
This chapter assesses ultrathin films and the interfaces between two different materials. In this case, the adsorbate–adsorbate interactions are often just as or even more important than the substrate–adsorbate interactions. The driving force behind work in this area is the application of surface science in the microelectronics industry. In recent years, it has been found that if a complete layer of one material is grown on another, the competition between adsorbate–adsorbate interaction and substrate–adsorbate interaction leads to some very interesting properties for the overlayer film that are quite different to those observed for the bulk material. These different properties can be electronic, structural, chemical, and/or magnetic and may be significant in terms of catalysis.
8
Juo, Anthony S. R., e Kathrin Franzluebbers. "Soil Chemistry". In Tropical Soils. Oxford University Press, 2003. http://dx.doi.org/10.1093/oso/9780195115987.003.0006.
Testo completoAbstract (sommario):
Soil chemistry deals with the chemical properties and reactions of soils. It is essentially the application of electrochemistry and colloid chemistry to soil systems. Major topics include surface charge properties of soil colloids, cation and anion sorption and exchange, soil acidity, soil alkalinity, soil salinity, and the effects of these chemical properties and processes on soil biological activity, plant growth, and environmental quality. The ability of the electrically charged surface of soil colloids to retain nutrient cations and anions is an important chemical property affecting the fertility status of the soil. There are two major sources of electrical charges on soil organic and inorganic colloids, namely, permanent or constant charges and variable or pH-dependent charges. Permanent or constant charges are the result of the charge imbalance brought about by isomorphous substitution in a mineral structure of one cation by another of similar size but differing valence (see also section 2.3.2). For example, the substitution of Mg2+ for Al3+ that occurs in Al-dominated octahedral sheets of 2:1 clay minerals results in a negative surface charge in smectite, vermiculite, and chlorite. The excess negative charges are then balanced by adsorbed cations to maintain electrical neutrality. Permanent negative charges of all 2:1 silicate minerals arise from isomorphous substitutions. The l:l-type clay mineral, kaolinite, has only a minor amount of permanent charge due to isomorphic substitution. The negative charges on kaolinite originate from surface hydroxyl groups on the edge of the mineral structure and are pH-dependent. Variable or pH-dependent charges occur on the surfaces of Fe and Al oxides, allophanes, and organic soil colloids. This type of surface charge originates from hydroxyl groups and other functional groups by releasing or accepting H+ ions, resulting in either negative or positive charges. Other functional groups are hydroxyl (OH) groups of Fe and/or Al oxides and allophanes and the COOH and OH groups of soil organic matter. Variable-charge soil colloids bear either a positive or a negative net surface charge depending on the pH of the soil. The magnitude of the charge varies with the electrolyte concentration of the soil solution.
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Sleight, Arthur W. "Introduction to Heterogeneous Catalysts". In Solid State Chemistry, 166–81. Oxford University PressOxford, 1992. http://dx.doi.org/10.1093/oso/9780198551669.003.0005.
Testo completoAbstract (sommario):
Abstract An aspect of inorganic solids that has frequently been neglected by solid state chemists is the catalytic property. The reason for this neglect can be primarily attributed to the great difficulty of achieving a detailed understanding of surface structure and reactivity. Certainly, it has been true that reliable mechanistic information on heterogeneously catalysed reactions is rarely achieved. Even on an empirical level, good correlations between catalytic properties and the chemistry of the catalyst itself have been largely lacking. Fortunately, advanced techniques and instrumentation for microstructure and surface studies are now allowing rapid strides to be made in the area of heterogeneous catalysis. Indeed, many obvious and potentially highly revealing experiments within our grasp are waiting to be done. Surface properties of solids are of paramount importance for heterogeneous catalysis. One would like to know the active site density on each crystallographic surface of a solid, and one would also like to know if these active sites are related to dangling bonds due to coordinatively unsaturated surface sites or if they are related to special defects. In a few cases, we are beginning to obtain answers to these questions, and the rate of progress is increasing.
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Jolivet, Jean-Pierre. "Surface Chemistry and Physicochemistry of Oxides". In Metal Oxide Nanostructures Chemistry. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780190928117.003.0008.
Testo completoAbstract (sommario):
Oxide particles resulting from precipitation have at least one dimension less than a few nanometers. Therefore, as their specific area (surface-to-mass ratio) may reach several hundred square meters per gram, the behavior of these particles is closely related to their surface physical-chemical characteristics. Thus, the dispersion state of particles in solution is dependent on attractive and repulsive forces between surfaces. The balance control of these forces limits the aggregation of particles and promotes the formation of sols or gels, or, contrariwise, flocculates the particles and separates them from a suspension. The divison state of solids resulting from precipitation is ruled by forces that exert themselves onto the surface (interfacial—or surface—tension). They determine the extent of the surface area and, therefore, the particle size. Adsorption of ions or molecules within the dispersion depends on forces exerting between soluble species and the surface. These forces may be due to electrostatic charges on the surface. They may also be due to the ability of the surface cations to be coordinated by soluble species and/or the ability of surface oxygenated groups to coordinate cations from solution. The attachment of various species on the surface of oxide particles plays a major role in various fields—for instance, the transport of matter in natural or industrial waters, catalysis and corrosion phenomena, formation of stable and homogeneous dispersions. It is somewhat difficult to characterize the surface of nanometer-sized objects from structural as well as chemical standpoints. The geometry of such small particles is not easily defined with precision, and the surface often includes defects such as steps, truncations, and stacking faults. These sites are difficult to recognize but exhibit largely variable chemical reactivities. In addition, the study of the oxide– solution interface is complicated because few of its physical quantities are experimentally accessible. These quantities are treated as fitting parameters in more or less complex modelings. The current state of the art, however, allows suitable interpretation of experimental data.
Atti di convegni sul tema "One-surface chemistry"
1
Cao, Liang, Qi Xue, Yi Zheng, Yuan Tian, Tao Hang, Yunwen Wu e Ming Li. "Grafting low-k organic films onto copper surface by one-step electrografting method via aryldiazonium chemistry". In 2022 23rd International Conference on Electronic Packaging Technology (ICEPT). IEEE, 2022. http://dx.doi.org/10.1109/icept56209.2022.9873160.
Testo completo
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Pemberton, Jeanne E. "Surface Raman Scattering as a Probe of Metal Surface Chemistry". In Laser Applications to Chemical Analysis. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/laca.1992.thb1.
Testo completoAbstract (sommario):
Raman scattering is an attractive probe of surface and interfacial chemistry at metals due to the high degree of molecular specificity inherent in the results. One aspect of Raman scattering that enhances its utility for the study of metal surfaces is the ability to deduce orientational information about molecules at these metal surfaces from the presence of oriented electric fields at these surfaces with which selective vibrational modes can couple. These "surface selection rules" have been both theoretically described and experimentally validated for a variety of metal surfaces. Given the wealth of information available from such studies, potential applications for surface Raman scattering span the range from electrochemical to catalytic systems. Thus, considerable effort has been expended in an attempt to develop Raman scattering for the study of surface and interfacial phenomena. These efforts have largely been focused on overcoming problems attendant to sensitivity and selectivity for the interface in the presence of the bulk environment.
3
Bakshi, Shrishty, Kezheng Li, Pin Dong, Steven Johnson e Thomas Krauss. "Mussel inspired polydopamine surface chemistry as a one step method for bioreceptor immobilisation on silicon photonic biosensors". In 2023 IEEE BioSensors Conference (BioSensors). IEEE, 2023. http://dx.doi.org/10.1109/biosensors58001.2023.10280885.
Testo completo
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Johzuka, Junko, e Toshihiro Ona. "One hour <em>in vivo</em>-like phenotypic screening system for anti-cancer drugs using a high precision surface plasmon resonance device". In 6th International Electronic Conference on Medicinal Chemistry. Basel, Switzerland: MDPI, 2020. http://dx.doi.org/10.3390/ecmc2020-07366.
Testo completo
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Altfeder, I. B., D. M. Chen e K. A. Matveev. "Electron Interference Fringes on a Pb Quantum Wedge". In Chemistry and Physics of Small-Scale Structures. Washington, D.C.: Optica Publishing Group, 1997. http://dx.doi.org/10.1364/cps.1997.ctub.1.
Testo completoAbstract (sommario):
Optical Fizeau fringes appear when a monochromatic light illuminates the surface of a thin optically transparent wedge. As the wavelength of the Fermi electrons in a metal is by a factor of 1000 smaller then the wavelength of light, one could expect to observe the similar phenomenon of electron interference fringes on a nanometer thickness metal wedge. The perfect tool to detect the electron interference pattern is a scanning tunneling microscope (STM), as it can probe the local density of states (LDOS), and test the interference conditions for the Fermi electrons. Indeed, the STM has been used successfully to reveal different surface interference phenomena (1-4).
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Liu, Zilong, Hayati Onay, Fengzhi Guo e Pegah Hedayati. "Electrochemically Assisted Deposition of Calcium Carbonate Surfaces for Anionic Surfactant Adsorption: Implications for Enhanced Oil Recovery". In SPE International Conference on Oilfield Chemistry. SPE, 2021. http://dx.doi.org/10.2118/204283-ms.
Testo completoAbstract (sommario):
Abstract Surface roughness of rocks had a significant influence on surfactant adsorption in enhanced oil recovery (EOR), both in terms of the total amount adsorbed as well as of the kinetics of adsorption. Combining electrochemical techniques and quartz crystal microbalance with dissipation monitoring (QCM) into one analysis setup opens up new avenues for depositing model rock surfaces and investigating the adsorption behavior. Using electrochemically assisted deposition, uniform and well-covered metal-CaCO3 sensors were obtained to simulate rough carbonate rocks and characterized by scanning electron microscope with energy dispersive X-ray analysis (SEM-EDX). The deposition process was controlled by the nitrate and oxygen electroreduction reactions in the presence of bicarbonate and calcium ions. The deposited mass of CaCO3 was calculated and the coverages for Au-CaCO3 and Pt-CaCO3 sensors were between 20 - 60%. It is observed that mostly cubic-like CaCO3 crystals were formed with crystal sizes around 20 to 50 µm from the SEM micrographs. The bigger crystals were surrounded by bare regions of Pt surface, suggesting the existence of Ostwald ripening process. Prior to the investigation of the deposited CaCO3 surfaces, the adsorption of anionic surfactant alcohol alkoxy sulfate (AAS) was studied on a smooth commercial CaCO3 surface with varying pH and CaCl2concentrations using QCM. Subsequently, surfactant adsorption was performed on the rough deposited CaCO3 surfaces and their adsorption behavior were compared. On a smooth CaCO3 surface, a fast adsorption of AAS surfactant was observed, whereas the desorption process was characterized as a two-step process. Compared to the smooth CaCO3surface, an increase of the frequency shift of about 5 times was observed on the deposited CaCO3 surfaces. This observation was mainly ascribed to the rougher surfaces, having more adsorption sites for AAS binding, and also the liquid trapping effect, resulting in more frequency shifts. It is suggested that a rough model mineral surface could be a better representation of a rock surface, presenting the implications of the new understanding for surfactant adsorption on different rock surfaces in EOR.
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Yu, Fuwei, Lida Wang, Ben Liu, Mengqi Ma, Fan Liu, Lixia Kang, Hanqiao Jiang e Junjian Li. "Flow Dynamics of Microemulsion-Forming Surfactants and its Implications for Enhanced Oil Recovery: A Microfluidic Study". In SPE International Conference on Oilfield Chemistry. SPE, 2021. http://dx.doi.org/10.2118/204378-ms.
Testo completoAbstract (sommario):
Abstract The microfluidic experiments were conducted in this paper to clarify the flow dynamics of in situ microemulsion and further understand its EOR performances. Two kinds of 2.5D glass micromodel with varied depths of pore and throat are fabricated. One is designed for the imbibition tests, which consists of two fractures and a tight matrix. Another one is a fractured micromodel designed for the flooding tests. The micromodels are originally water wet, and can be altered to oil wet through the surface modification. At the same time, three microemulsion-forming surfactant solutions at the salinity of type I, II or III were prepared, respectively. Then the flow dynamics of these three surfactant solutions during imbibition and flooding process were visualized by the microfluidic experiments. Results show that the type I surfactant solution realizes the highest oil recovery rate in both water-wet and oil-wet imbibition micromodels. Meanwhile, the type III surfactant solution realize the highest oil recovery in both water-wet and oil-wet fractured micromodels.
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Eryiğit, Resul, e Irving P. Herman. "Optical Response of GaAs(001) Surfaces for Monitoring and Control of Atomic-Layer-Defined Processing". In Chemistry and Physics of Small-Scale Structures. Washington, D.C.: Optica Publishing Group, 1997. http://dx.doi.org/10.1364/cps.1997.csud.1.
Testo completoAbstract (sommario):
Progress in the miniaturization of electronic devices, the emergence of compound semiconductors in optoelectronics applications, and the development of quantum device structures based on nanostructures can continue only with an improved understanding and control of surfaces and interfacial regions. One important way to achieve such control is by real-time measurements during growth and etching. In addition to the standard surface-analysis techniques that require near ultrahigh vacuum (UHV) conditions (such as XPS, LEED, and EELS), there is a need for noninvasive real-time surface probes with submonolayer sensitivity that will be applicable to either the UHV environment of a molecular beam epitaxy (MBE) chamber or the atmospheric-pressure environment of an organometallic vapor phase epitaxy (OMVPE) reactor. Optical probes can be used during either type of processing.
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Luo, Zhaoyu, Parvez Sukheswalla, Scott A. Drennan, Mingjie Wang e P. K. Senecal. "3D Numerical Simulations of Selective Catalytic Reduction of NOx With Detailed Surface Chemistry". In ASME 2017 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/icef2017-3658.
Testo completoAbstract (sommario):
Environmental regulations have put stringent requirements on NOx emissions in the transportation industry, essentially requiring the use of exhaust after-treatment on diesel fueled light and heavy-duty vehicles. Urea-Water-Solution (UWS) based Selective Catalytic Reduction (SCR) for NOx is one the most widely adopted methods for achieving these NOx emissions requirements. Improved understanding and optimization of SCR after-treatment systems is therefore vital, and numerical investigations can be employed to facilitate this process. For this purpose, detailed and numerically accurate models are desired for in-cylinder combustion and exhaust after-treatment. The present paper reports on 3-D numerical modeling of the Urea-Water-Solution SCR system using Computational Fluid Dynamics (CFD). The entire process of Urea injection, evaporation, NH3 formation and NOx reduction is numerically investigated. The simulation makes use of a detailed kinetic surface chemistry mechanism to describe the catalytic reactions. A multi-component spray model is applied to account for the urea evaporation and decomposition process. The CFD approach also employs an automatic meshing technique using Adaptive Mesh Refinement (AMR) to refine the mesh in regions of high gradients. The detailed surface chemistry NOx reduction mechanism validated by Olsson et al. (2008) is applied in the SCR region. The simulations are run using both transient and steady-state CFD solvers. While transient simulations are necessary to reveal sufficient details to simulate catalytic oxidation during transient engine processes or under cyclic variations, the steady-state solver offers fast and accurate emission solutions. The simulation results are compared to available experimental data, and good agreement between experimental data and model results is observed.
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Spicka, Kevin, Lisa Holding Eagle, Chris Longie, Kyle Dahlgren, AJ Gerbino, Alex Koerner e Greg Loder. "Theories and Work Towards Understanding a Mysterious Case of Severe Bakken Brine Incompatibility". In SPE International Conference on Oilfield Chemistry. SPE, 2021. http://dx.doi.org/10.2118/204358-ms.
Testo completoAbstract (sommario):
Abstract The Bakken formation is well known for producing brine very high in total dissolved solids (TDS). Halite, calcium carbonate, and barium sulfate scales all can pose substantial production challenges. Trademarks of Bakken produced brine include elevated concentrations of sodium (>90,000 mg/L), chloride (>200,000 mg/L), and calcium (>30,000 mg/L), contrasted against low concentration of bicarbonate (50-500 mg/L). In the past 3 years, operators have experienced unexpected instances of severe calcium carbonate scale on surface where produced fluids from the production tubing commingled with the gas produced up the casing. Initially treated as one-off scale deposits despite the application of scale inhibitor, acid remediation jobs or surface line replacement were typical solutions. As time has passed, this issue has become more and more prevalent across the Bakken. Investigation of this surface issue discovered a most unexpected culprit: a low TDS, high alkalinity brine (up to 92,000 mg/L alkalinity measured to date) produced up the casing with the gas. When mixing with the high calcium brine typically produced in the Bakken, the resulting incompatibility posed remarkable scale control challenges. The uniqueness of this challenge required thorough analytical work to confirm the species and concentrations of the dissolved ions in the brine produced with the gas. Scale control products were tested to evaluate their abilities and limitations regarding adequate control of this massive incompatibility. The theory that corrosion contributed to this situation has been supported by a unique modelling approach. Once corrosion was identified as the likely source of the high alkalinity brine, corrosion programs were instituted to help address the surface scaling. This paper highlights the evaluations conducted to fully grasp the severity of the incompatibility, the theories put forth to date, work conducted to try to replicate the phenomena in the lab and in models, and chemical programs used in the field to address corrosion and scale. While not known to exist in other oilfield basins, conventional or unconventional, this discovery may have implications for the broader industry if similar situations occur. The possible explanations for why this may be happening may have implications for scale control, asset integrity, and potentially even the methods by which wells are produced.
Rapporti di organizzazioni sul tema "One-surface chemistry"
1
Hinrichs, Claudia, e Judith Hauck. Report on skill of CMIP6 models to simulate alkalinity and improved parameterizations for large scale alkalinity distribution. OceanNets, giugno 2022. http://dx.doi.org/10.3289/oceannets_d4.4.
Testo completoAbstract (sommario):
In part one of this deliverable, an ensemble of 14 CMIP6 Earth System Models is evaluated regarding their performance in simulating alkalinity and related parameters. The majority of the models and the multi-model-mean underestimate surface alkalinity compared to climatological observations. Alkalinity biases stemming from the parametrization of calcium carbonate formation and dissolution can be as big as biases stemming from model physics. In part two, we test the sensitivity of parametrizations concerning the carbonate chemistry in the FESOM2.1-REcoM3 and give recommendations for addressing alkalinity biases.
2
Husson, Scott M., Viatcheslav Freger e Moshe Herzberg. Antimicrobial and fouling-resistant membranes for treatment of agricultural and municipal wastewater. United States Department of Agriculture, gennaio 2013. http://dx.doi.org/10.32747/2013.7598151.bard.
Testo completoAbstract (sommario):
This research project introduced a novel membrane coating strategy to combat biofouling, which is a major problem for the membrane-based treatment of agricultural and municipal wastewaters. The novelty of the strategy is that the membrane coatings have the unique ability to switch reversibly between passive (antifouling) and active (antimicrobial) fouling control mechanisms. This dual-mode approach differs fundamentally from other coating strategies that rely solely on one mode of fouling control. The research project had two complementary objectives: (1) preparation, characterization, and testing of dual-mode polymer nanolayers on planar surfaces and (2) evaluation of these nanolayers as membrane modifiers. The first objective was designed to provide a fundamental understanding of how polymer nanolayer chemistry and structure affect bacterial deposition and to demonstrate the reversibility of chemical switching. The second objective, which focused on membrane development, characterization, and testing, was designed to demonstrate methods for the production of water treatment membranes that couple passive and active biofouling control mechanisms. Both objectives were attained through synergistic collaboration among the three research groups. Using planar silicon and glass surfaces, we demonstrated using infrared spectroscopy that this new polymer coating can switch reversibly between the anti-fouling, zwitterion mode and an anti-microbial, quaternary amine mode. We showed that switching could be done more than 50 times without loss of activity and that the kinetics for switching from a low fouling zwitterion surface to an antimicrobial quaternary amine surface is practical for use. While a low pH was required for switching in the original polymer, we illustrated that by slightly altering the chemistry, it is possible to adjust the pH at which the switching occurs. A method was developed for applying the new zwitterionic surface chemistry onto polyethersulfone (PES) ultrafiltration membranes. Bacteria deposition studies showed that the new chemistry performed better than other common anti-fouling chemistries. Biofilm studies showed that PESultrafiltration membranes coated with the new chemistry accumulated half the biomass volume as unmodified membranes. Biofilm studies also showed that PES membranes coated with the new chemistry in the anti-microbial mode attained higher biofilm mortality than PES membranes coated with a common, non-switchablezwitterionic polymer. Results from our research are expected to improve membrane performance for the purification of wastewaters prior to use in irrigation. Since reduction in flux due to biofouling is one of the largest costs associated with membrane processes in water treatment, using dual-mode nanolayer coatings that switch between passive and active control of biofouling and enable detachment of attached biofoulants would have significant economic and societal impacts. Specifically, this research program developed and tested advanced ultrafiltration membranes for the treatment of wastewaters. Such membranes could find use in membrane bioreactors treating municipal wastewater, a slightly upgraded version of what presently is used in Israel for irrigation. They also may find use for pretreatment of agricultural wastewaters, e.g., rendering facility wastewater, prior to reverse osmosis for desalination. The need to desalinate such impaired waters water for unlimited agricultural use is likely in the near future.
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Shannon. L51584 Effect of Water Chemistry on Internal Corrosion Rates in Offshore Pipelines.pdf. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), marzo 1988. http://dx.doi.org/10.55274/r0010643.
Testo completoAbstract (sommario):
This work is an extension of a program reported in 1984 to establish factors which control corrosion of API line pipe in gas containing carbon dioxide and water. In this phase of the program, there were four objectives. One was to establish the temperature of maximum corrosion in the range of 75�, 100� and 175�F at 1000 psi in water saturated with carbon dioxide at partial pressures of 15 and 50 psia. The next was to explore the role of carbon content and microstructure in the steel, iron carbonate film formation, and resulting corrosion rates. The third was to examine the role of pre-existing mill scale and corrosion films on accelerating pitting attack. The final objective was to extend a spread sheet computer model to calculate corrosion rates from field data. Tests were run in a refreshed, recirculating autoclave at a total pressure of 1000 psi in water saturated with CO2 at partial pressures of 15 and 50 psia, and containing bicarbonate ion to adjust the pH either to 5 or 6. Six materials were tested: ASTM-A53B, two lots of API5LX-X52 and three lots of API5LX-X60. Samples were pulled at intervals for weight loss corrosion and to examine the surface films by electron microscope and metallography. After plotting the weight loss results, corrosion rates in mils per year (MPY) were calculated. The microstructure of the metal, the corrosion films of iron carbonate, and the weight loss results were then examined. The corrosion data were incorporated into a spread sheet computer model for users to calculate their own pipe line corrosion rates.
4
Kidder, J. A., M. B. McClenaghan, M I Leybourne, M. W. McCurdy, P. Pelchat, D. Layton-Matthews, C. E. Beckett-Brown e A. Voinot. Geochemical data for stream and groundwaters around the Casino Cu-Au-Mo porphyry deposit, Yukon (NTS 115 J/10 and 115 J/15). Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/328862.
Testo completoAbstract (sommario):
This open file reports geochemical data for stream and groundwater samples collected around the Casino porphyry Cu-Au-Mo deposit, one of the largest and highest-grade deposits of its kind in Canada. The calc-alkaline porphyry is hosted in a Late Cretaceous quartz monzonite and associated breccias in the unglaciated region of west central Yukon. Water chemistry around the deposit was investigated because: (i) the deposit has not yet been disturbed by mining; (ii) the deposit was known to have metal-rich waters in local streams; and (iii) the deposit has atypically preserved ore zones. Stream water samples were collected at 22 sites and groundwater samples were collected from eight sites. Surface and groundwaters around the Casino deposit are anomalous with respect to Cd (up to 5.4 µg/L), Co (up to 64 µg/L), Cu (up to 1657 µg/L), Mo (up to 25 µg/L), As (up to 17 µg/L), Re (up to 0.7 µg/L), and Zn (up to 354 µg/L) concentrations. The stable isotopes of O and H of the groundwaters are essentially identical to the surface waters and plot close to the local and global meteoric water lines, indicating that the waters represent modern recharge, consistent with the generally low salinities of all the waters (total dissolved solids range from 98 to 1320 mg/L). Sulfur and Sr isotopes are consistent with proximal waters interacting with the Casino rocks and mineralization; a sulfide-rich bedrock sample from the deposit has delta-34S = -1.2 permille and proximal groundwaters are only slightly heavier (-0.3 to 3.1 permille). These geochemical and isotopic results indicate that surface water geochemistry is a suitable medium for mineral exploration for porphyry-style mineralization in the Yukon, and similar unglaciated regions in Canada. The atypical geochemical signature (Mo, Se, Re, As, Cu) of these types of deposits are typically reflected in the water chemistry and S isotopes provide a more local vectoring tool.
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Watson, Mark, Martyn Wilmott e Brian Erno. GRI-96-0452_2 Stress Corrosion Cracking Under Field Simulated Conditions II. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), novembre 1997. http://dx.doi.org/10.55274/r0011974.
Testo completoAbstract (sommario):
The pH of solutions found under disbonded polyethylene tape coatings in the field is generally in the range of 6.5 to 7.5. Electrochemically determining corrosion rates for pipeline steels exposed to neutral pH solutions in this pH range indicate that corrosion rates are too low to account for the observed crack growth rates from field excavation programs. This suggests that for the SCC process to be based on a simple dissolution mechanism then the pH at the crack tip would have to be lower than the bulk solution pH. A computer model was developed to determine solution chemistry changes within an SCC crack under anaerobic conditions as a function of time The numerical simulation model showed that the pH at a crack tip is lower by at least one pH unit than the trapped electrolyte outside the crack. A second thermodynamic model was used to show that under appropriate conditions dilute groundwater can be converted to a concentrated carl ornately bicarbonate solution. High temperatures were not required to concentrate on this solution. The concentration of this electrolyte under coal tar or asphalt coatings can occur by a cyclical process in which groundwater levels fluctuate and in tum influence the ability of cathodic protection to reach the steel surface. The high pH is generated by effective cathodic protection and the carbonate concentration is developed by absorption of CO2 from soil gases.
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Raymond, Kara, Laura Palacios, Cheryl McIntyre e Evan Gwilliam. Status of climate and water resources at Saguaro National Park: Water year 2019. A cura di Alice Wondrak Biel. National Park Service, dicembre 2021. http://dx.doi.org/10.36967/nrr-2288717.
Testo completoAbstract (sommario):
Climate and hydrology are major drivers of ecosystems. They dramatically shape ecosystem structure and function, particularly in arid and semi-arid ecosystems. Understanding changes in climate, groundwater, and water quality and quantity is central to assessing the condition of park biota and key cultural resources. The Sonoran Desert Network collects data on climate, groundwater, and surface water at 11 National Park Service units in south-ern Arizona and New Mexico. This report provides an integrated look at climate, groundwater, and springs conditions at Saguaro National Park (NP) during water year 2019 (October 2018–September 2019). Annual rainfall in the Rincon Mountain District was 27.36" (69.49 cm) at the Mica Mountain RAWS station and 12.89" (32.74 cm) at the Desert Research Learning Center Davis station. February was the wettest month, accounting for nearly one-quarter of the annual rainfall at both stations. Each station recorded extreme precipitation events (>1") on three days. Mean monthly maximum and minimum air temperatures were 25.6°F (-3.6°C) and 78.1°F (25.6°C), respectively, at the Mica Mountain station, and 37.7°F (3.2°C) and 102.3°F (39.1°C), respectively, at the Desert Research Learning Center station. Overall temperatures in WY2019 were cooler than the mean for the entire record. The reconnaissance drought index for the Mica Mountain station indicated wetter conditions than average in WY2019. Both of the park’s NOAA COOP stations (one in each district) had large data gaps, partially due to the 35-day federal government shutdown in December and January. For this reason, climate conditions for the Tucson Mountain District are not reported. The mean groundwater level at well WSW-1 in WY2019 was higher than the mean for WY2018. The water level has generally been increasing since 2005, reflecting the continued aquifer recovery since the Central Avra Valley Storage and Recovery Project came online, recharging Central Arizona Project water. Water levels at the Red Hills well generally de-clined starting in fall WY2019, continuing through spring. Monsoon storms led to rapid water level increases. Peak water level occurred on September 18. The Madrona Pack Base well water level in WY2019 remained above 10 feet (3.05 m) below measuring point (bmp) in the fall and winter, followed by a steep decline starting in May and continuing until the end of September, when the water level rebounded following a three-day rain event. The high-est water level was recorded on February 15. Median water levels in the wells in the middle reach of Rincon Creek in WY2019 were higher than the medians for WY2018 (+0.18–0.68 ft/0.05–0.21 m), but still generally lower than 6.6 feet (2 m) bgs, the mean depth-to-water required to sustain juvenile cottonwood and willow trees. RC-7 was dry in June–September, and RC-4 was dry in only September. RC-5, RC-6 and Well 633106 did not go dry, and varied approximately 3–4 feet (1 m). Eleven springs were monitored in the Rincon Mountain District in WY2019. Most springs had relatively few indications of anthropogenic or natural disturbance. Anthropogenic disturbance included spring boxes or other modifications to flow. Examples of natural disturbance included game trails and scat. In addition, several sites exhibited slight disturbance from fires (e.g., burned woody debris and adjacent fire-scarred trees) and evidence of high-flow events. Crews observed 1–7 taxa of facultative/obligate wetland plants and 0–3 invasive non-native species at each spring. Across the springs, crews observed four non-native plant species: rose natal grass (Melinis repens), Kentucky bluegrass (Poa pratensis), crimson fountaingrass (Cenchrus setaceus), and red brome (Bromus rubens). Baseline data on water quality and chemistry were collected at all springs. It is likely that that all springs had surface water for at least some part of WY2019. However, temperature sensors to estimate surface water persistence failed...