Chemistry Transition Research Articles

Modeling Complex Systems by Structural Invariants Approach

When modeling complex systems, we usually encounter the following difficulties: partiality, large amount of data, and uncertainty of conclusions. It can be said that none of the known approaches solves these difficulties perfectly, especially in cases where we expect emergences in the complex system. The most common is the physical approach, sometimes reinforced by statistical procedures. The physical approach to modeling leads to a complicated description of phenomena associated with a relatively simple geometry. If we assume emergences in the complex system, the physical approach is not appropriate at all. In this article, we apply the approach of structural invariants, which has the opposite properties: a simple description of phenomena associated with a more complicated geometry (in our case pregeometry). It does not require as much data and the calculations are simple. The price paid for the apparent simplicity is a qualitative interpretation of the results, which carries a special type of uncertainty. Attention is mainly focused (in this article) on the invariant matroid and bases of matroid (M, BM) in combination with the Ramsey graph theory. In addition, this article introduces a calculus that describes the emergent phenomenon using two quantities—the power of the emergent phenomenon and the complexity of the structure that is associated with this phenomenon. The developed method is used in the paper for modeling and detecting emergent situations in cases of water floods, traffic jams, and phase transition in chemistry.

Student success and the high school-university transition: 100 years of chemistry education research

The 100th anniversary of the first article (published in 1921) examining student success and the high school to university transition in chemistry provides an excellent opportunity to consider what has – and has not – changed in chemistry education. This review details the development and findings of chemistry education research specifically as it relates to student learning and success over this extended time period. After considering the changing educational context and definition of success, this research will be described under three main themes: different ways of knowing (learning objectives and outcomes), thinking (scientific reasoning and problem solving), and learning (preferences and approaches to studying). A key finding is that while our understanding of effective teaching and learning has advanced significantly since the early 1900s, so too have the curriculum expectations and cognitive demands placed upon students increased significantly. Thus despite the many advances and innovations in chemistry education, an achievement gap persists between high school and post-secondary education for many students to this day. A comprehensive picture of the factors influencing student success developed from the research literature not only helps understand this disconnect; it also provides an opportunity to reflect on lessons learned for teaching, learning, and directions for future research.

Phase Transition as an Emergent Phenomenon Analysed by Violation of Structural Invariant (M, BM)

When modeling complex systems, we usually encounter the following difficulties: partiality, large amounts of data and uncertainty of conclusions. The most common approach used for modeling is the physical approach, sometimes reinforced by statistical procedures. If we assume emergences in the complex system, a physical approach is not appropriate at all. Instead, we build here the approach of structural invariants. In this paper, we show that another plane can be built above the plane of physical description, which is responsible for violation of structural invariants. Main attention is concentrated (in this article) on the invariant matroid and bases of matroid (M, BM) in combination with Ramsey graph theory. In addition, the article introduces a calculus that describes the emergent phenomena using two quantities - the power of the emergent phenomenon and the complexity of the structure of the considered complex system. We show the application of the method for modeling phase transition in chemistry.

Kinetic modeling investigation on the coupling effects of H2 and CO2 addition on the laminar flame speed of hydrogen enriched biogas mixture

The numerical simulation was conducted to investigate the coupling effects of H2 and CO2 on the laminar flame speed and reaction pathways of the biogas-hydrogen mixtures. The same proportions of H2 and CO2 were considered in the study. The dilution effects, chemical effects and thermal effects of H2 and CO2 were isolated, while the contributions of different effects were also calculated to identify the dominating factor. The results show that H radical pool plays the important role in the variation of laminar flame speed of biogas-hydrogen mixture. The coupling dilution effects of H2 and CO2 lead to the considerable decrease of H radical and dominate the decreased laminar flame speed. The H2 chemical effects improve R84 (OH + H2 = H2O + H) and R3 (O + H2 = H + OH) quite effectively, which results in the reduced dropping trends of H radical and laminar flame speed from BG60H40 to BG40H60. The CO2 chemical effects suppress the major H radical production reactions of R84, R3, R99 (OH + CO = H + CO2) and R10 (O + CH3 = H + CH2O) more apparently at the fuel-rich condition, while importance of major consumption reactions (R53: H + CH4 = CH3+H2, R52: H + CH3(+M) = CH4(+M) and R58: H + CH2O = HCO + H2) are higher at the fuel-rich condition. This dominates the more evident decrease of H radical and laminar flame speed at the fuel-rich condition. Based on the ROP analysis, R3, R46 (H + HO2 = 2OH), R52, R84, R99 and R158 (2CH3(+M) = C2H6(+M)) have the major contributions on the chemistry transition caused by the coupling effects of H2 and CO2. The decreased contribution of R158 and R99 indicate the weakened CH4-related chemistry while the increased contributions of R3, R46, R52 and R84 indicate the improved H2-related chemistry in the biogas-hydrogen flame. Furthermore, coupling effects of H2 and CO2 or H2/CO2-related chemistry can be monitored by the contribution variations of R84 and R99 on the OH radical concentration.

The interplay of spatial organization and biochemistry in building blocks of cellular signalling pathways.

Biochemical pathways and networks are central to cellular information processing. While a broad range of studies have dissected multiple aspects of information processing in biochemical pathways, the effect of spatial organization remains much less understood. It is clear that space is central to intracellular organization, plays important roles in cellular information processing and has been exploited in evolution; additionally, it is being increasingly exploited in synthetic biology through the development of artificial compartments, in a variety of ways. In this paper, we dissect different aspects of the interplay between spatial organization and biochemical pathways, by focusing on basic building blocks of these pathways: covalent modification cycles and two-component systems, with enzymes which may be monofunctional or bifunctional. Our analysis of spatial organization is performed by examining a range of 'spatial designs': patterns of localization or non-localization of enzymes/substrates, theoretically and computationally. Using these well-characterized in silico systems, we analyse the following. (i) The effect of different types of spatial organization on the overall kinetics of modification, and the role of distinct modification mechanisms therein. (ii) How different information processing characteristics seen experimentally and studied from the viewpoint of kinetics are perturbed, or generated. (iii) How the activity of enzymes (bifunctional enzymes in particular) may be spatially manipulated, and the relationship between localization and activity. (iv) How transitions in spatial organization (encountered either through evolution or through the lifetime of cells, as seen in multiple model organisms) impacts the kinetic module (and pathway) behaviour, and how transitions in chemistry may be impacted by prior spatial organization. The basic insights which emerge are central to understanding the role of spatial organization in biochemical pathways in both bacteria and eukaryotes, and are of direct relevance to engineering spatial organization of pathways in bottom-up synthetic biology in cellular and cell-free systems.

Reactive Wetting of Atomic Layer Deposition Al2O3 By Molten Lithium Metal

Oxide coating presents a promising methodology to enable reactive wetting of solid-state garnet electrolyte by molten lithium metal. The resulting intimate contact allows effective lithium-ion migration at the garnet/lithium metal interface. Although changing in coating composition by the interfacial reaction has been previously revealed, the transition in chemistry, structure, topography and mechanical performance of the contact coating area remain unclear. Here, a combination of impedance spectroscopy, scanning electron microscope, time-of-flight secondary ion mass spectrometry and nanoindentation is devoted to illustrating and discussing the effect of the interfacial reaction in altering the properties of atomic layer deposition alumina coating layer. These findings provide unique insight into the mechanism of the reactive wetting of oxide coating by molten lithium metal, thereby, enabling design of more effective lithium metal-solid electrolyte interfaces.

Needs and Gaps for Catalysis in Addressing Transitions in Chemistry and Energy from a Sustainability Perspective.

Catalysis is undergoing a major transition resulting from significant changes in chemical and energy production. To honor the 50th anniversary of establishing the Jerzy Haber Institute of Catalysis and Surface Chemistry, this Essay discusses, from a forward-looking, personal and somewhat provocative perspective, the needs and gaps of catalysis to address the ongoing transition in chemistry and energy from a sustainability perspective. The focus is on a few selected aspects identified as crucial: i) The precise synthesis of catalytic materials, particularly focusing on mesoporous molecular sieves, metal-organic frameworks, and zeolites (particularly two-dimensional type); ii) advanced catalyst characterization methods; iii) new concepts and approaches needed in catalysis to meet the demands of a field of energy and chemistry in transition.

Filling the Space of Possibilities: Eighteenth-Century Chemistry's Transition from Art to Science

The ArgumentThis paper charts eighteenth-century chemistry's transition from its definition as an art to its proclaimed status as a science. Both the general concept of art and specific practices of eighteenth-century chemists are explored to account for this transition. As a disciplined activity, art orients practitioners' attention toward particular directions and away from others, providing a structured space of possibilities within which their discipline develops. Consequently, while chemists throughout the eighteenth century aspired to reveal nature's “true voice,” the path of their investigations was directed by and toward their laboratory manipulations. So long as the chemical community maintained an ethos of polite cooperation and eschewed theoretical wrangling, this point was hidden by a rhetoric of “matter of fact” reporting. But as “facts” mounted in the 1770s and 1780s, especially in pneumatic chemistry, cooperation gave way to contention as chemists sought to name and organize their findings without the guidance of a communally accepted “natural” system. Lavoisier and his fellow “new” chemists offered a forceful solution to this dilemma by introducing a revolutionary network of theories, nomenclature, and instruments that unabashedly fused the productive manipulation of their laboratory work with what they claimed as the structure and activity of nature.

A Word and the World: The Significance of Naming the Calorimeter

Previous articleNext article No AccessA Word and the World: The Significance of Naming the CalorimeterLissa RobertsLissa Roberts Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by Isis Volume 82, Number 2Jun., 1991 Publication of the History of Science Society Article DOIhttps://doi.org/10.1086/355725 Views: 10Total views on this site Citations: 8Citations are reported from Crossref Copyright 1991 History of Science Society, Inc.PDF download Crossref reports the following articles citing this article:Leonidas G. Ioannou, Josh Foster, Nathan B. Morris, Jacob F. Piil, George Havenith, Igor B. Mekjavic, Glen P. Kenny, Lars Nybo, Andreas D. Flouris Occupational heat strain in outdoor workers: A comprehensive review and meta-analysis, Temperature 9, no.11 (Apr 2022): 67–102.https://doi.org/10.1080/23328940.2022.2030634Mi Gyung Kim From phlogiston to caloric: chemical ontologies, Foundations of Chemistry 13, no.33 (Oct 2011): 201–222.https://doi.org/10.1007/s10698-011-9116-yDavid C. Frankenfield On heat, respiration, and calorimetry, Nutrition 26, no.1010 (Oct 2010): 939–950.https://doi.org/10.1016/j.nut.2010.01.002Yujing Li, Lars Wadsö, Lennart Larsson, Jonny Bjurman Correlating two methods of quantifying fungal activity: Heat production by isothermal calorimetry and ergosterol amount by gas chromatography–tandem mass spectrometry, Thermochimica Acta 458, no.1-21-2 (Jun 2007): 77–83.https://doi.org/10.1016/j.tca.2007.01.005Ruth Benschop What Is a Tachistoscope? Historical Explorations of an Instrument, Science in Context 11, no.11 (Sep 2008): 23–50.https://doi.org/10.1017/S0269889700002908 Bibliography, Osiris 9, no.11 (Oct 2015): 237–242.https://doi.org/10.1086/368738Theodore M. Porter Making Things Quantitative, Science in Context 7, no.33 (Sep 2008): 389–407.https://doi.org/10.1017/S0269889700001757Lissa Roberts Filling the Space of Possibilities: Eighteenth-Century Chemistry's Transition from Art to Science, Science in Context 6, no.22 (Sep 2008): 511–553.https://doi.org/10.1017/S0269889700001496

Oxidation of small boron cluster ions (B+1–13) by oxygen

Absolute cross sections for all ionic products formed in reactions of B+1–13 with oxygen have been measured under single collision conditions, at collision energies from 0.25 to 10 eV. Three main reaction mechanisms appear to be important: oxidative fragmentation, collision induced dissociation, and boron atom abstraction. The dominant oxidation process are exoergic for all cluster sizes, but appear to have bottlenecks or activation barriers for the larger cluster ions. Clusters smaller than B+6 have similar chemistry, then there is a sharp transition in chemistry for clusters larger than B+6 . Correlations are explored between cluster reactivity and cluster stability, and the oxidation chemistry is compared to the similar results found for aluminum cluster ion oxidation.

Zur Sozialgeschichte des chemischen Hochschulfaches im 18. Jahrhundert

AbstractThe social history of chemistry as an academic discipline is dealt with in terms of competing programs of research and institutionalization, focussing on chemistry's transition from a medical curriculum to an economic and scientific context, as exemplified by universities such as Greifswald, Halle, Göttingen, and Jena in the late eighteenth century. Special attention is given to those factors that constitute, stabilize, and, eventually, re‐formulate disciplinary identity.

Essay Review: Transition in Chemistry: The English Paracelsians

Essay Review: Transition in Chemistry: The English Paracelsians