Littérature scientifique sur le sujet « Diverse Thermodynamics Properties »
Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres
Consultez les listes thématiques d’articles de revues, de livres, de thèses, de rapports de conférences et d’autres sources académiques sur le sujet « Diverse Thermodynamics Properties ».
À côté de chaque source dans la liste de références il y a un bouton « Ajouter à la bibliographie ». Cliquez sur ce bouton, et nous générerons automatiquement la référence bibliographique pour la source choisie selon votre style de citation préféré : APA, MLA, Harvard, Vancouver, Chicago, etc.
Vous pouvez aussi télécharger le texte intégral de la publication scolaire au format pdf et consulter son résumé en ligne lorsque ces informations sont inclues dans les métadonnées.
Articles de revues sur le sujet "Diverse Thermodynamics Properties"
1
Bonilla, Steve L., Sarah K. Denny, John H. Shin, Aurora Alvarez-Buylla, William J. Greenleaf et Daniel Herschlag. « High-throughput dissection of the thermodynamic and conformational properties of a ubiquitous class of RNA tertiary contact motifs ». Proceedings of the National Academy of Sciences 118, no 33 (9 août 2021) : e2109085118. http://dx.doi.org/10.1073/pnas.2109085118.
Texte intégralRésumé :
Despite RNA’s diverse secondary and tertiary structures and its complex conformational changes, nature utilizes a limited set of structural “motifs”—helices, junctions, and tertiary contact modules—to build diverse functional RNAs. Thus, in-depth descriptions of a relatively small universe of RNA motifs may lead to predictive models of RNA tertiary conformational landscapes. Motifs may have different properties depending on sequence and secondary structure, giving rise to subclasses that expand the universe of RNA building blocks. Yet we know very little about motif subclasses, given the challenges in mapping conformational properties in high throughput. Previously, we used “RNA on a massively parallel array” (RNA-MaP), a quantitative, high-throughput technique, to study thousands of helices and two-way junctions. Here, we adapt RNA-MaP to study the thermodynamic and conformational properties of tetraloop/tetraloop receptor (TL/TLR) tertiary contact motifs, analyzing 1,493 TLR sequences from different classes. Clustering analyses revealed variability in TL specificity, stability, and conformational behavior. Nevertheless, natural GAAA/11ntR TL/TLRs, while varying in tertiary stability by ∼2.5 kcal/mol, exhibited conserved TL specificity and conformational properties. Thus, RNAs may tune stability without altering the overall structure of these TL/TLRs. Furthermore, their stability correlated with natural frequency, suggesting thermodynamics as the dominant selection pressure. In contrast, other TL/TLRs displayed heterogenous conformational behavior and appear to not be under strong thermodynamic selection. Our results build toward a generalizable model of RNA-folding thermodynamics based on the properties of isolated motifs, and our characterized TL/TLR library can be used to engineer RNAs with predictable thermodynamic and conformational behavior.
2
Soni, Surbhi, Gunjan Chauhan, Bhawna Pareek, Pankaj Sharma et Rajan Chopra. « Binary Liquid Mixtures Nonanol and Decanol with their Thermodynamic and Transport Behavior : A Review ». Research Journal of Chemistry and Environment 26, no 9 (25 août 2022) : 167–74. http://dx.doi.org/10.25303/2609rjce1670174.
Texte intégralRésumé :
The extensive knowledge about structural phenomena of mixtures is of indispensable importance in the development of theories in liquid state. The information about structural and molecular interactions of liquid mixtures is quite vital from both fundamental and engineering point of view and can be utilized for further studies. For a better understanding of the non-ideal behavior of complex systems, fundamental thermodynamic and thermo-physical properties are the varied sources in which information is required. The excess thermodynamic properties are very sensitive to variables such as size, shape, composition, temperature and pressure, therefore an important information about the differences in the intermolecular interactions was obtained using these binary liquid mixtures under a range of physiochemical conditions. By using thermodynamics quantities, we can calculate the deviation of thermodynamics properties from those of an ideal mixture. These properties are necessary for the development of thermodynamic models required in optimized processes of the chemical, petrochemical, pharmaceutical and other industries. Along with diverse industrial applications, binary liquid mixtures can have hazardous effects such as pollutants causing air, water and soil contamination and some of them may have cancerous features. Their organic compounds and derivatives prepared from them are employed in a range of industrial and consumer applications such as perfumes, cosmetics, paints, varnishes, drugs, fuels, explosives, fats, dyes, waxes, resins, plastics, rubber, detergents, DDT etc. making them commercially important.
3
Gujrati, Purushottam Das. « Foundations of Nonequilibrium Statistical Mechanics in Extended State Space ». Foundations 3, no 3 (23 août 2023) : 419–548. http://dx.doi.org/10.3390/foundations3030030.
Texte intégralRésumé :
The review provides a pedagogical but comprehensive introduction to the foundations of a recently proposed statistical mechanics (μNEQT) of a stable nonequilibrium thermodynamic body, which may be either isolated or interacting. It is an extension of the well-established equilibrium statistical mechanics by considering microstates mk in an extended state space in which macrostates (obtained by ensemble averaging A^) are uniquely specified so they share many properties of stable equilibrium macrostates. The extension requires an appropriate extended state space, three distinct infinitessimals dα=(d,de,di) operating on various quantities q during a process, and the concept of reduction. The mechanical process quantities (no stochasticity) like macrowork are given by A^dαq, but the stochastic quantities C^αq like macroheat emerge from the commutator C^α of dα and A^. Under the very common assumptions of quasi-additivity and quasi-independence, exchange microquantities deqk such as exchange microwork and microheat become nonfluctuating over mk as will be explained, a fact that does not seem to have been appreciated so far in diverse branches of modern statistical thermodynamics (fluctuation theorems, quantum thermodynamics, stochastic thermodynamics, etc.) that all use exchange quantities. In contrast, dqk and diqk are always fluctuating. There is no analog of the first law for a microstate as the latter is a purely mechanical construct. The second law emerges as a consequence of the stability of the system, and cannot be violated unless stability is abandoned. There is also an important thermodynamic identity diQ≡diW≥0 with important physical implications as it generalizes the well-known result of Count Rumford and the Gouy-Stodola theorem of classical thermodynamics. The μNEQT has far-reaching consequences with new results, and presents a new understanding of thermodynamics even of an isolated system at the microstate level, which has been an unsolved problem. We end the review by applying it to three different problems of fundamental interest.
4
Mei, Baicheng, Yuxing Zhou et Kenneth S. Schweizer. « Experimental test of a predicted dynamics–structure–thermodynamics connection in molecularly complex glass-forming liquids ». Proceedings of the National Academy of Sciences 118, no 18 (26 avril 2021) : e2025341118. http://dx.doi.org/10.1073/pnas.2025341118.
Texte intégralRésumé :
Understanding in a unified manner the generic and chemically specific aspects of activated dynamics in diverse glass-forming liquids over 14 or more decades in time is a grand challenge in condensed matter physics, physical chemistry, and materials science and engineering. Large families of conceptually distinct models have postulated a causal connection with qualitatively different “order parameters” including various measures of structure, free volume, thermodynamic properties, short or intermediate time dynamics, and mechanical properties. Construction of a predictive theory that covers both the noncooperative and cooperative activated relaxation regimes remains elusive. Here, we test using solely experimental data a recent microscopic dynamical theory prediction that although activated relaxation is a spatially coupled local–nonlocal event with barriers quantified by local pair structure, it can also be understood based on the dimensionless compressibility via an equilibrium statistical mechanics connection between thermodynamics and structure. This prediction is found to be consistent with observations on diverse fragile molecular liquids under isobaric and isochoric conditions and provides a different conceptual view of the global relaxation map. As a corollary, a theoretical basis is established for the structural relaxation time scale growing exponentially with inverse temperature to a high power, consistent with experiments in the deeply supercooled regime. A criterion for the irrelevance of collective elasticity effects is deduced and shown to be consistent with viscous flow in low-fragility inorganic network-forming melts. Finally, implications for relaxation in the equilibrated deep glass state are briefly considered.
5
Nashed, Gamal. « General form of the analytic function f(T) in diverse dimension for a static planar spacetime ». International Journal of Modern Physics D 28, no 12 (septembre 2019) : 1950158. http://dx.doi.org/10.1142/s021827181950158x.
Texte intégralRésumé :
We derive an exact static solution in diverse dimension, without any constraints, to the field equations of [Formula: see text] gravitational theory using a planar spacetime with two unknown functions, i.e. [Formula: see text] and [Formula: see text]. The black hole solution is characterized by two constants, [Formula: see text] and [Formula: see text], one is related to the mass of the black hole, [Formula: see text], and the other is responsible to make the solution deviate from the teleparallel equivalent of general relativity (TEGR). We show that the analytic function [Formula: see text] depends on the constant [Formula: see text] and becomes constant function when [Formula: see text] which corresponds to the TEGR case. The interesting property of this solution is the fact that it makes the singularity of the Kretschmann invariant much softer than the TEGR case. We calculate the energy of this black hole and show that it is equivalent to ADM mass. Applying a coordinate transformation, we derive a rotating black hole with nontrivial values of the torsion scalar and [Formula: see text]. Finally, we examine the physical properties of this black hole solution using the laws of thermodynamics and show that it has thermodynamical stability.
6
Guvench, Olgun, Devon Martin et Megan Greene. « Pyranose Ring Puckering Thermodynamics for Glycan Monosaccharides Associated with Vertebrate Proteins ». International Journal of Molecular Sciences 23, no 1 (31 décembre 2021) : 473. http://dx.doi.org/10.3390/ijms23010473.
Texte intégralRésumé :
The conformational properties of carbohydrates can contribute to protein structure directly through covalent conjugation in the cases of glycoproteins and proteoglycans and indirectly in the case of transmembrane proteins embedded in glycolipid-containing bilayers. However, there continue to be significant challenges associated with experimental structural biology of such carbohydrate-containing systems. All-atom explicit-solvent molecular dynamics simulations provide a direct atomic resolution view of biomolecular dynamics and thermodynamics, but the accuracy of the results depends on the quality of the force field parametrization used in the simulations. A key determinant of the conformational properties of carbohydrates is ring puckering. Here, we applied extended system adaptive biasing force (eABF) all-atom explicit-solvent molecular dynamics simulations to characterize the ring puckering thermodynamics of the ten common pyranose monosaccharides found in vertebrate biology (as represented by the CHARMM carbohydrate force field). The results, along with those for idose, demonstrate that the CHARMM force field reliably models ring puckering across this diverse set of molecules, including accurately capturing the subtle balance between 4C1 and 1C4 chair conformations in the cases of iduronate and of idose. This suggests the broad applicability of the force field for accurate modeling of carbohydrate-containing vertebrate biomolecules such as glycoproteins, proteoglycans, and glycolipids.
7
Casanellas, Jordi, et Ilídio Lopes. « The Sun and stars : Giving light to dark matter ». Modern Physics Letters A 29, no 37 (4 décembre 2014) : 1440001. http://dx.doi.org/10.1142/s021773231440001x.
Texte intégralRésumé :
During the last century, with the development of modern physics in such diverse fields as thermodynamics, statistical physics, and nuclear and particle physics, the basic principles of the evolution of stars have been successfully well understood. Nowadays, a precise diagnostic of the stellar interiors is possible with the new fields of helioseismology and astroseismology. Even the measurement of solar neutrino fluxes, once a problem in particle physics, is now a powerful probe of the core of the Sun. These tools have allowed the use of stars to test new physics, in particular the properties of the hypothetical particles that constitute the dark matter (DM) of the Universe. Here we present recent results obtained using this approach.
8
Hassan, Mohsan, Sajid Ali, Walid Aich, Faical Khlissa, Badreddine Ayadi et Lioua Kolsi. « Transport pattern of Non-Newtonian mass and thermal energy under two diverse flow conditions by using modified models for thermodynamics properties ». Case Studies in Thermal Engineering 29 (janvier 2022) : 101714. http://dx.doi.org/10.1016/j.csite.2021.101714.
Texte intégral
9
Hofmeister, Anne M. « Dependence of Heat Transport in Solids on Length-Scale, Pressure, and Temperature : Implications for Mechanisms and Thermodynamics ». Materials 14, no 2 (18 janvier 2021) : 449. http://dx.doi.org/10.3390/ma14020449.
Texte intégralRésumé :
Accurate laser-flash measurements of thermal diffusivity (D) of diverse bulk solids at moderate temperature (T), with thickness L of ~0.03 to 10 mm, reveal that D(T) = D∞(T)[1 − exp(−bL)]. When L is several mm, D∞(T) = FT−G + HT, where F is constant, G is ~1 or 0, and H (for insulators) is ~0.001. The attenuation parameter b = 6.19D∞−0.477 at 298 K for electrical insulators, elements, and alloys. Dimensional analysis confirms that D → 0 as L → 0, which is consistent with heat diffusion, requiring a medium. Thermal conductivity (κ) behaves similarly, being proportional to D. Attenuation describing heat conduction signifies that light is the diffusing entity in solids. A radiative transfer model with 1 free parameter that represents a simplified absorption coefficient describes the complex form for κ(T) of solids, including its strong peak at cryogenic temperatures. Three parameters describe κ with a secondary peak and/or a high-T increase. The strong length dependence and experimental difficulties in diamond anvil studies have yielded problematic transport properties. Reliable low-pressure data on diverse thick samples reveal a new thermodynamic formula for specific heat (∂ln(cP)/∂P = −linear compressibility), which leads to ∂ln(κ)/∂P = linear compressibility + ∂lnα/∂P, where α is thermal expansivity. These formulae support that heat conduction in solids equals diffusion of light down the thermal gradient, since changing P alters the space occupied by matter, but not by light.
10
Currie, Simon L., et Michael K. Rosen. « Using quantitative reconstitution to investigate multicomponent condensates ». RNA 28, no 1 (12 novembre 2021) : 27–35. http://dx.doi.org/10.1261/rna.079008.121.
Texte intégralRésumé :
Many biomolecular condensates are thought to form via liquid–liquid phase separation (LLPS) of multivalent macromolecules. For those that form through this mechanism, our understanding has benefitted significantly from biochemical reconstitutions of key components and activities. Reconstitutions of RNA-based condensates to date have mostly been based on relatively simple collections of molecules. However, proteomics and sequencing data indicate that natural RNA-based condensates are enriched in hundreds to thousands of different components, and genetic data suggest multiple interactions can contribute to condensate formation to varying degrees. In this Perspective, we describe recent progress in understanding RNA-based condensates through different levels of biochemical reconstitutions as a means to bridge the gap between simple in vitro reconstitution and cellular analyses. Complex reconstitutions provide insight into the formation, regulation, and functions of multicomponent condensates. We focus on two RNA–protein condensate case studies: stress granules and RNA processing bodies (P bodies), and examine the evidence for cooperative interactions among multiple components promoting LLPS. An important concept emerging from these studies is that composition and stoichiometry regulate biochemical activities within condensates. Based on the lessons learned from stress granules and P bodies, we discuss forward-looking approaches to understand the thermodynamic relationships between condensate components, with the goal of developing predictive models of composition and material properties, and their effects on biochemical activities. We anticipate that quantitative reconstitutions will facilitate understanding of the complex thermodynamics and functions of diverse RNA–protein condensates.
Thèses sur le sujet "Diverse Thermodynamics Properties"
1
Hajji, Mohammed Saïd. « Etude comparative de l'association hydrophobe en solution aqueuse de tensioactifs anioniques et cationiques et de divers alcane-diols et alcane-triols par mesures des masses volumiques, de la diffusion élastique et quasi-élastique de la lumière et des ». Paris 13, 1987. http://www.theses.fr/1987PA132016.
Texte intégralChapitres de livres sur le sujet "Diverse Thermodynamics Properties"
1
Chimowitz, Eldred H. « Thermodynamic Scaling Near the Critical Point ». Dans Introduction to Critical Phenomena in Fluids. Oxford University Press, 2005. http://dx.doi.org/10.1093/oso/9780195119305.003.0005.
Texte intégralRésumé :
Thermodynamic scaling near the critical point is a signature of critical phenomena, and many useful applications of supercritical solvent fluids depend upon exploiting this behavior in some technologically interesting way. Near the critical point, many transport and thermodynamic properties show anomalous behavior which is usually linked to the divergence of certain thermodynamic properties, such as the fluid’s isothermal compressibility. In figures 3.1 and 3.2 we depict the near-critical behavior of both the density of xenon and the thermal conductivity of carbon dioxide, respectively, adapted from published data [1, 2]. The onset of what appear to be critical singularities in these properties is clearly evident in both instances. In this chapter, we focus upon the thermodynamic basis for this type of behavior. In the theory of critical phenomena, the limiting behavior of certain thermodynamic properties near the critical point assumes special significance. In particular, properties that diverge at the critical point are of interest, and this divergence is usually described in terms of scaling laws.
2
Latora, Vito, et Massimo Marchiori. « The Architecture of Complex Systems ». Dans Nonextensive Entropy. Oxford University Press, 2004. http://dx.doi.org/10.1093/oso/9780195159769.003.0027.
Texte intégralRésumé :
At the present time, the most commonly accepted definition of a complex system is that of a system containing many interdependent constituents which interact nonlinearly. Therefore, when we want to model a complex system, the first issue has to do with the connectivity properties of its network, the architecture of the wirings between the constituents. In fact, we have recently learned that the network structure can be as important as the nonlinear interactions between elements, and an accurate description of the coupling architecture and a characterization of the structural properties of the network can be of fundamental importance also in understanding the dynamics of the system. In the last few years the research on networks has taken different directions producing rather unexpected and important results. Researchers have: (1) proposed various global variables to describe and characterize the properties of realworld networks and (2) developed different models to simulate the formation and the growth of networks such as the ones found in the real world. The results obtained can be summed up by saying that statistical physics has been able to capture the structure of many diverse systems within a few common frameworks, though these common frameworks are very different from the regular array, or capture the random connectivity, previously used to model the network of a complex system. Here we present a list of some of the global quantities introduced to characterize a network: the characteristic path length L, the clustering coefficient C, the global efficiency E<sub>glob</sub>, the local efficiency E<sub>loc</sub>, the cost Cost, and the degree distribution P(k). We also review two classes of networks proposed: smallworld and scale-free networks. We conclude with a possible application of the nonextensive thermodynamics formalism to describe scale-free networks. Watts and Strogatz [17] have shown that the connection topology of some biological, social, and technological networks is neither completely regular nor completely random. These networks, that are somehow in between regular and random networks, have been named small worlds in analogy with the smallworld phenomenon empirically observed in social systems more than 30 years ago [11, 12].
3
Irzhak, Tamara F., et Vadim I. Irzhak. « Synthesis of Epoxy Nanocomposites ». Dans Nanotechnology in Aerospace and Structural Mechanics, 34–79. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-7921-2.ch002.
Texte intégralRésumé :
The formation processes of epoxy nanocomposites with carbon (nanotubes, graphene, and graphite), metal-containing, and aluminosilicate (montmorillonite and halloysite tubes) fillers are considered. A high reactivity of epoxy groups and a thermodynamic miscibility of epoxy oligomers with many substances make it possible to use diverse curing agents and to accomplish curing reactions under various technological conditions. Epoxy nanocomposites are designed to realize to the same extent the unique functional properties of nanoparticles: electric, magnetic, optical, chemical, and biological. The mutual effect of both a matrix and nanoparticles on the composite formation is discussed.
4
Irzhak, Tamara F., et Vadim I. Irzhak. « Synthesis of Epoxy Nanocomposites ». Dans Research Anthology on Synthesis, Characterization, and Applications of Nanomaterials, 225–60. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-8591-7.ch010.
Texte intégralRésumé :
The formation processes of epoxy nanocomposites with carbon (nanotubes, graphene, and graphite), metal-containing, and aluminosilicate (montmorillonite and halloysite tubes) fillers are considered. A high reactivity of epoxy groups and a thermodynamic miscibility of epoxy oligomers with many substances make it possible to use diverse curing agents and to accomplish curing reactions under various technological conditions. Epoxy nanocomposites are designed to realize to the same extent the unique functional properties of nanoparticles: electric, magnetic, optical, chemical, and biological. The mutual effect of both a matrix and nanoparticles on the composite formation is discussed.
5
Zinn-Justin, Jean. « Critical phenomena : General considerations. Mean-field theory (MFT) ». Dans Quantum Field Theory and Critical Phenomena, 324–56. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198834625.003.0014.
Texte intégralRésumé :
This chapter is devoted to a brief review of general properties of phase transitions in macroscopic physics and, in particular in lattice models. Some of these lattice models actually appear as lattice regularizations of Euclidean (imaginary time) quantum physics theory (QFT). Most of the transitions considered in this work have the following character: spins on the lattice, or macroscopic particles in the continuum, interact through short-range forces, assumed, for simplicity, to decay exponentially. For simple systems, it is possible to find a local observable, called order parameter, whose expectation values depend on the phase in the several phase region, for example, the spin in ferromagnetic systems. In the disordered phase, the connected two-point function decreases exponentially at large distance, at a rate characterized by the correlation length (the inverse of the smallest physical mass in particle physics). In continuous transitions, the correlation length diverges at the critical temperature. Within the mean-field approximation (consistent with Landau's theory of critical phenomena), it can be shown that the singular behaviour of thermodynamic quantities at the critical temperature is universal. These properties can also be reproduced by calculating correlation functions with a perturbed Gaussian measure. It is then shown that the leading corrections to the mean-field approximation, in Ising-like systems, diverge at the critical temperature for dimensions smaller than or equal to $4$.
Actes de conférences sur le sujet "Diverse Thermodynamics Properties"
1
El-Sadi, Haifa. « Using Engineering Equation Solver (EES) to Solve Engineering Problems in Mechanical Engineering ». Dans ASME 2018 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/imece2018-86078.
Texte intégralRésumé :
This paper studies the use of an engineering equation solver (EES) software to improve the students’ perceptive of the Air conditioning and Nozzle analysis in courses such as heat transfer and applied gas dynamics. EES lets students to concentrate on design engineering applications. Also the students will have the skill to see instant results to differences of the design circumstances as well as diverse parameters that would touch diverse categories of engineering projects. The proposed tool also gives students the ability to determine thermodynamics properties of any fluid, solve different mathematical equations with many variables and perform optimization and analysis. In this paper, condenser of air conditioning as a heat transfer project was used as an example to demonstrate EES to the students. The student’s feedback shows that the use of the proposed tool significantly improves the student learning experience in thermodynamics and heat transfer courses and other mechanical engineering courses such as thermal design analysis, make the course more dynamic, and motivate the students to learn the material fast and effectively.
2
Pahari, Swagata, Prasenjit Ghosh et Rabindra Mukhopadhyay. « Prediction of Thermodynamic and Viscoelastic Properties of Rubber Using Molecular Simulations ». Dans International Conference on Automotive Materials and Manufacturing AMM 2023. 400 Commonwealth Drive, Warrendale, PA, United States : SAE International, 2023. http://dx.doi.org/10.4271/2023-28-1312.
Texte intégralRésumé :
<div class="section abstract"><div class="htmlview paragraph">Rubber is one of the most versatile materials and finds numerous applications in diverse areas. The application of rubber is mostly determined by its physico-mechanical and viscoelastic properties. Rubber properties play an essential role in performing its functional requirement, which is crucial for designing a good rubber product. Therefore, the estimation and prediction of the properties of rubber and rubber composites are central to the material developers. However, many factors, such as temperature, environmental effects, and rubber formulation can influence rubber properties and make it highly non-linear. Computer simulation plays a vital role in our understanding of complex dynamics in rubber materials and provide structure-property relationship at the nanoscopic and microscopic level. An understanding of this relationship can reduce the expensive trial experiments and provide a benchmark for novel material design. Additionally, simulations at atomic and molecular levels provide the mechanism of action and the underlying physics which finally helps in designing of new materials. In the present work, all atomistic Molecular Dynamics (MD) simulation technique is utilized to predict various thermodynamic and viscoelastic properties of raw rubbers. The effect of key structural factors, that govern the properties of rubber at the molecular level, is examined using MD. In this work, we have developed the classical atomistic models for several raw rubbers and implemented methodologies for calculating their properties from MD simulations. The predicted properties using our model and methodologies are in close agreement with the experimental and available literature values. Our results establish that MD simulations are an effective tool to predict quantitatively thermodynamic and viscoelastic properties of rubber. Eventually, the same technique can be used to predict properties for crosslinked rubber, rubber composites, blends, and silica/carbon black reinforced rubbers and thus, designing a novel rubber material.</div></div>