Thermodynamics Research Papers - Academia.edu (original) (raw)

Organisms inherit a set of environmental regularities as well as genes, and these two inheritances repeatedly encounter each other across generations. This repetition drives natural selection to coordinate the interplay of stably replicated genes with stably persisting environmental regularities, so that this web of interactions produces the reliable development of a functionally organized design. Selection is the only known counterweight to the tendency of physical systems to lose rather than grow functional organization. This means that the individually unique and unpredictable factors in the web of developmental interactions are a disordering threat to normal development. Selection built anti-entropic mechanisms into organisms to orchestrate transactions with environments so that they have some chance of being organization-building and reproduction-enhancing rather than disordering. Evolutionary psychology was founded on a new theory of development that encompasses, reformulates, and (we believe) logically reconciles other views such as nativism, environmentalism, interactionism, developmental systems theory, and others. Readers who want to understand what evolutionary psychologists actually think about development need to consult the original sources (see, e.g., Tooby & Cosmides, 1990, 1992) rather than relying on critics' misconceptions. Below, we address several confusions. Deficiencies in Basic Biology Because developmental systems theorists are psychologists rather than a more interdisciplinarily inclusive team, it is not surprising that they also provide questionable characterizations of fields outside of psychology, such as genetics, developmental biology, and evolutionary biology (e.g.

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- Marketing, Genetics, Psychology, Cognitive Science

The goal of this study was to experimentally test the additivity of the electrostatic substituent effects (SEs) for the aromatic stacking interaction. The additivity of the SEs was assessed using a small molecule model system that could adopt an offset face-to-face aromatic stacking geometry. The intramolecular interactions of these molecular torsional balances were quantitatively measured via the changes in a folded/unfolded conformational equilibrium. Five different types of substituents were examined (CH 3 , OCH 3 , Cl, CN, and NO 2 ) that ranged from electron-donating to electron-withdrawing. The strength of the intramolecular stacking interactions was measured for 21 substituted aromatic stacking balances and 21 control balances in chloroform solution. The observed stability trends were consistent with additive SEs. Specifically, additive SE models could predict SEs with an accuracy from ±0.01 to ±0.02 kcal/mol. The additive SEs were consistent with Wheeler and Houk's direct SE model. However, the indirect or polarization SE model cannot be ruled out as it shows similar levels of additivity for two to three substituent systems, which were the number of substituents in our model system. SE additivity also has practical utility as the SEs can be accurately predicted. This should aid in the rational design and optimization of systems that utilize aromatic stacking interactions.

The paper focused on linking the theory of thermodynamics with the factors of the stock market. The paper tried to show the working of the financial system, considering the stock market, by creating an analogy with the elements of the thermodynamics with the stock market. The four laws of thermodynamics universally accepted in the theory of physics. The zeroth law can determine the return from the market by the eagerness or participation of investors and the volume of shares traded in the market. The first law can measure the efficiency of the market. The second law can determine the randomness of the market, and finally, the third law can determine the randomness using the market capitalization for a specific time.

- by Rashesh Vaidya
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- Thermodynamics, Econophysics/ Math Modelling/ Physics

O presente trabalho teve por objetivos avaliar a composição de rizomas do lírio-do-bejo (Hedychium coronarium) e isolar e caracterizar seu amido, por meio de análises físicas e físico-químicas. A composição química dos grânulos de amido isolados dos rizomas também foi determinada, bem como o formato, tamanho, distribuição de tamanho de partícula por difração a laser, viscosidade de pasta em analisador rápido de viscosidade, poder de inchamento, índice de solubilidade em água, propriedade térmica por calorimetria diferencial de varredura e cristalinidade por difração de raios X. Observou-se que os rizomas apresentaram elevado teor de água e baixos teores de matéria graxa, carboidratos, cinzas, proteínas e fibras. Os rizomas de lírio-do-brejo apresentam-se inadequados para produção de amido, devido ao baixo teor de matéria seca (17,3%), com 21,97% de amido, bem como fibras longas e látex, que dificultam a extração do amido. O amido extraído apresentou pureza de 99,2%, com 37,2% de ami...

- by Wellington F E R R E I R A Moura
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- Mathematics, Physics, Thermodynamics, Chemistry

Two thermodynamically based, theoretical models are developed to predict the selectivity coefficients for Ca 2 + / Cu 2 + and Pb 2 + /Cu 2 + in ion flotation with sodium dodecylsulfate (SDS) as the collector. Pseudo selectivity coefficients predicted from surface tension measurements are 1.12 and 1.69 for Ca 2 + /Cu 2 + and Pb 2 + /Cu 2 + . This agrees rather poorly with experimentally measured selectivity coefficients of 1.44 and 2.14, but does predict the order of selectivity Cu 2 + BCa 2 + BPb 2 + . The selectivity coefficients estimated by the dehydration model are 1.55 and 2.07 for Ca 2 + /Cu 2 + and Pb 2 + /Cu 2 + , respectively, which agrees well with the experimentally measured values.

- by Fiona Doyle
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- Engineering, Thermodynamics, Physical sciences, CHEMICAL SCIENCES

Most industrially applied polymer resins and composites have low surface free energy and lack polar functional groups on their surface, resulting in inherently poor adhesion properties. A strong research momentum to understand polymer adhesion in the last decade has been motivated by the growing needs of the automotive and aerospace industries for better adhesion of components and surface coatings. This paper reviews the recent research efforts on polymer adhesion with a special focus on adhesion mechanisms. It starts with an introduction to adhesion with explanatory notes on adhesion phenomena. Recent research on the adhesion mechanisms of mechanical coupling, chemical bonding and thermodynamic adhesion is then discussed. The area of adhesion promoters is reviewed with the focus on plasma and chemical treatments, along with direct methods for adhesion measurement. The topics of polymer blends and reactive polymerization are considered and the interactions with adhesion mechanisms are reported. The concluding section provides recommendations regarding future research on the contentious aspects of currently accepted adhesion mechanisms and on strategies for enhancing polymer adhesion strength.

- by Bronwyn Fox
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- Engineering, Thermodynamics, Adhesion, Diffusion

Quantitative analysis of the composition dependence of the concentration gradient of each species of macromolecule within a solution mixture at sedimentation equilibrium permits the quantitative characterization of self-and heterointeractions between sedimenting solutes. Sedimentation equilibrium experiments were conducted on solutions containing a trace concentration of FITClabeled BSA in varying concentrations of Ficoll 70 and on solutions containing a trace concentration of FITC-labeled Ficoll 70 in varying concentrations of BSA. The equilibrium gradient of each solute component in each mixture was measured independently. Analysis of the resulting gradients resulted in evaluation of the dependence of the activity coefficient of Ficoll upon the concentrations of Ficoll and BSA at concentrations of up to 100 g/L and the dependence of the activity coefficient of BSA upon the concentrations of Ficoll and BSA at concentrations of up to 100 g/L. The activity coefficients of both species increase significantly with increasing Ficoll and BSA concentration and do not vary with temperature, to within the precision of measurement, over the temperature range of 5-37 °C, indicating that the dominant interaction between Ficoll molecules and between BSA and Ficoll molecules is repulsive and probably due to steric volume exclusion. The measured dependences may be accounted for quantitatively by a simple model in which BSA and Ficoll 70 are represented by equivalent rigid particles.

- by Allen Minton
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- Engineering, Thermodynamics, Fluorescent Dyes and Reagents, Physical sciences

In 1961, Rolf Landauer argued that the erasure of information is a dissipative process 1 . A minimal quantity of heat, proportional to the thermal energy and called the Landauer bound, is necessarily produced when a classical bit of information is deleted. A direct consequence of this logically irreversible transformation is that the entropy of the environment increases by a finite amount. Despite its fundamental importance for information theory and computer science 2-5 , the erasure principle has not been verified experimentally so far, the main obstacle being the difficulty of doing single-particle experiments in the low-dissipation regime. Here we experimentally show the existence of the Landauer bound in a generic model of a one-bit memory. Using a system of a single colloidal particle trapped in a modulated double-well potential, we establish that the mean dissipated heat saturates at the Landauer bound in the limit of long erasure cycles. This result demonstrates the intimate link between information theory and thermodynamics. It further highlights the ultimate physical limit of irreversible computation.

- by Artyom Petrosyan
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- Thermodynamics, Multidisciplinary, Nature

The concentration and transport of metals in hydrothermal solutions depend on how metals ions combine with ligands to form complexes, and experimental methods are necessary to identify the important complexes. UV-Vis-NIR spectrophotometry was used to study the formation of Cu(II)-chloride complexes in LiCl brines up to very high chlorinities (18 m LiCl), at temperatures between 25°C and 90°C. The number of Cu(II)-chloride complexes necessary to account for the variation in spectra with varying chloride molality at each temperature was estimated using principal component analysis. The molar absorptivity coefficients and concentrations of each complex were then determined using a "model-free" analysis, which does not require any assumption about the chemistry of the system, other than the number of absorbing species present. Subsequently, the results from the "model-free" analysis were integrated with independent experimental evidence to develop a thermodynamic speciation model, where the logarithms of the equilibrium constants for Cu(II)-chloride formation reactions were fitted to the data using a non-linear least-squares approach. Maps of the residual function were used to estimate uncertainties in the fitted equilibrium constants.

- by Leone Spiccia
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- Geology, Geochemistry, Thermodynamics, Principal Component Analysis
- by Rashid Abu Al-Rub
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- Thermodynamics, Atomistic Simulation, Finite Element, Shear bands

A continuación se obtiene la solución de tres ecuaciones diferenciales por medio de la utilización de transformada directa e inversa de Laplace con el objeto de establecer las técnicas básicas para la aplicación de la herramienta en esta... more

- by orlando cabrales
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- Thermodynamics

Partial or full solidification of metallurgical slags occurs in many industrial pyrometallurgical processes. To enhance the fundamental knowledge of this phenomenon, this research focuses on the simulation and in-situ observation of crystallizing minerals in oxide melts. The isothermal crystallization of Wollastonite (CaO.SiO 2 ) in a ternary CaO-Al 2 O 3 -SiO 2 melt is investigated. We used a confocal laser microscope (CLSM) to observe the dendritic crystallization and measured the dendrite tip radius and its velocity as a function of undercooling. The phase field method is chosen to model and simulate the crystallization, because it has proven its power for phase transformations in metals. The phase field model uses a vast number of physical input data, such as Gibbs energies of the phases, diffusion coefficients of the components and the interfacial energy of the solid-liquid interface. The thermodynamic data is retrieved from the FACTSage database for oxide systems. Diffusion coefficients are taken from literature, while surface energies are varied through the simulations. By comparing experimental values for the dendrite tip velocity with values obtained with simulations, the influence of surface energy and diffusion coefficients on the crystallization behavior can be assessed.

- by Nele Moelans
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- Materials Science, Thermodynamics, Crystallization, Diffusion

We review structure and dynamic measurements of biomembranes by atomic force microscopy (AFM). We focus mainly on studies involving supported lipid bilayers (SLBs), particularly formation by vesicle rupture on flat and corrugated surfaces, nucleation and growth of domains in phase-separated systems, anesthetic-lipid interactions, and protein/peptide interactions in multicomponent systems. We show that carefully designed experiments along with real-time AFM imaging with superior lateral and z resolution (0.1 nm) have revealed quantitative details of the mechanisms and factors controlling vesicle rupture, domain shape and size, phase transformations, and some model biological interactions. The AFM tip can also be used as a mechanical transducer and incorporated in electrochemical measurements of membrane components; therefore, we touch on these important applications in both model and cell membranes.

- by Marjorie Longo and +1
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- Chemical Engineering, Thermodynamics, Atomic Force Microscopy, Biological Sciences

We develop a geometric approach to complexity based on the principle that complexity requires interactions at different scales of description. Complex systems are more than the sum of their parts of any size, and not just more than the sum of their elements. Using information geometry, we therefore analyze the decomposition of a system in terms of an interaction hierarchy. In mathematical terms, we present a theory of complexity measures for finite random fields using the geometric framework of hierarchies of exponential families. Within our framework, previously proposed complexity measures find their natural place and gain a new interpretation.

- by Jürgen Jost
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- Applied Mathematics, Probability Theory, Stochastic Process, Thermodynamics

The shape of a differential thermal analysis (DTA) curve depends on the sample and the reference, the heating or cooling rates used in the experiment as also the thermal resistance to heat¯ow from the heat source to the cell containing the sample (or the reference), R a (R r). Having access to a database that contains the values of the sample heat capacity, C p , and those of the enthalpy of transformation, H, and calculating the parameters that depend on the apparatus, the cells and the reference, as well as the heating rate used, it is possible to determine the ÁT (T a À T r) values through the equation T a À T r R a dH dt R r C r dT r dt À R a C a dT a dt where C a is the heat capacity of the cell sample system and C b the heat capacity of the cell reference system. The comparison between the calculated and experimental values for ÁT enables an assessment to be made as to whether the modelled parameters are in agreement with the experimental information. This procedure enables a deeper perception of the thermal analysis in general and of the apparatus used in particular.

Molar excess volumes, VE, for pyridine (A) + a-picoline (B), + P-picoline (B) and + y-picoline (B) and benzene (A) + toluene (B), + o-xylene (B) and + p-xylene (B) and carbon tetrachloride (A) + n-heptane (B) have been measured dilatometrically as a function of temperature and composition and have been utilized to study B-B and B-B-B interactions in the presence of A via the Mayer-McMillan approach. A model has also been presented to account for these B-B and B-B-B interactions. The VE data at 308.15 K have also been analysed in terms of the "graph theoretical" approach which describes the I" data well for all these mixtures at 308.15 K. The "graph theoretical" approach has further been extended to successfully evaluate VE data for a mixture at any temperature, T,, when the VE data at T, are known.

- by PRANAY RAJ SINGH
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- Thermodynamics, Analytical Chemistry, Molecular Interactions

This paper discusses the sorption properties for U(VI) by alginate coated CaSO 4. 2H 2 O sepiolite and calcined diatomite earth (Kieselguhr) (ACSD). The removal of U(VI) from aqueous solution by sorption onto ACSF in a single component system with various contact times, pH, temperatures, and initial concentrations of U(VI) was investigated. The sorption patterns of uranium on the composite adsorbent followed the Langmuir, Freundlich and Dubinin-Radushkhevic (D-R) isotherms. The Freundlich, Langmuir, and D-R models have been applied and the data correlated well with Freundlich model and that the sorption was physical in nature (sorption energy, E a = 17.05 kJ/mol). The thermodynamic parameters such as variation of enthalpy ∆H, variation of entropy ∆S and variation of Gibbs free energy ∆G were calculated from the slope and intercept of lnK 0 vs. 1/T plots. Thermodynamic parameters (∆H ads = 31.83 kJ/mol, ∆S ads = 167 J/mol. K, ∆G°a ds (293.15 K) = −17.94 kJ/mol) showed the endothermic heat of sorption and the feasibility of the process. The thermodynamics of U(VI) ion/ACSD system indicates the spontaneous and endothermic nature of the process. It was noted that an increase in temperature resulted in a higher uranium loading per unit weight of the adsorbent.

- by Ramazan Donat
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- Thermodynamics, Analytical Chemistry, Inorganic Chemistry, Gibbs Free Energy

An efficient molecular simulation methodology has been developed to determine the positioning of water molecules in the binding site of a protein or protein-ligand complex. Occupancies and absolute binding free energies of water molecules are computed using a statistical thermodynamics approach. The methodology, referred to as JAWS, features "θ-water" molecules that can appear and disappear on a binding-site grid. Key approximations render the technique far more efficient than conventional free energy simulations. Testing of JAWS on five diverse examples (neuraminidase, scytalone dehydratase, major urinary protein 1, β-lactoglobulin, and COX-2) demonstrates its accuracy in locating hydration sites in comparison to results from high-resolution crystal structures. Possible applications include aid in refinement of protein crystal structures, drug lead optimization, setup of docking calculations and simulations of protein-ligand complexes.

- by Julian Tirado-rives
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- Engineering, Thermodynamics, Water, Computer Simulation

The modeling of the severe acute respiratory syndrome coronavirus helicase ATPase catalytic domain was performed using the protein structure prediction Meta Server and the 3D Jury method for model selection, which resulted in the identification of 1JPR, 1UAA and 1W36 PDB structures as suitable templates for creating a full atom 3D model. This model was further utilized to design small molecules that are expected to block an ATPase catalytic pocket thus inhibit the enzymatic activity. Binding sites for various functional groups were identified in a series of molecular dynamics calculation. Their positions in the catalytic pocket were used as constraints in the Cam-bridge structural database search for molecules having the pharmacophores that interacted most strongly with the enzyme in a desired position. The subsequent MD simulations followed by calculations of binding energies of the designed molecules were compared to ATP identifying the most successful candidates, for likely inhibitors-molecules possessing two phosphonic acid moieties at distal ends of the molecule.

A comprehensive model is developed for interfacial polymerization (IP), which provides new insights into the kinetics of film formation, the molecular weight distribution of the polymer as well as the mechanism of polymer precipitation. We incorporate a more general reaction scheme as well as polymer phase separation both by nucleation of the polymer-rich phase as well as by spinodal decomposition. The model predictions are verified against experimental data for unstirred Nylon 6-10 system. The model predicts that spinodal decomposition is the dominant mechanism of polymer phase separation at short reaction times. Film growth by nucleation of the polymer-rich phase dominates at larger times. The model also predicts the dominance of the nucleation mode of film growth with dilution of the organic phase. This model provides a further step towards a rational design and prediction of properties of membranes/capsules produced by interfacial polymerization.

- by Sudhir KULKARNI
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- Mechanical Engineering, Chemical Engineering, Thermodynamics, Kinetics

Hydrogen gas can be recovered from the microbial fermentation of organic substrates at high concentrations when interspecies hydrogen transfer to methanogens is prevented. Two techniques that have been used to limit methanogenesis in mixed cultures are heat treatment, to remove nonsporeforming methanogens from an inoculum, and low pH during culture growth. We found that high hydrogen gas concentrations (57-72%) were produced in all tests and that heat treatment (HT) of the inoculum (pH 6.2 or 7.5) produced greater hydrogen yields than low pH (6.2) conditions with a nonheat-treated inoculum (NHT). Conversion efficiencies of glucose to hydrogen (based on a theoretical yield of 4 mol-H 2 /mol-glucose) were as follows: 24.2% (HT, pH ) 6.2), 18.5% (HT, pH ) 7.5), 14.9% (NHT, pH ) 6.2), and 12.1% (NHT, pH ) 7.5). The main products of glucose (3 g-COD/L) utilization (g99%) in batch tests were acetate (3.4-24.1%), butyrate (6.4-29.4%), propionate (0.3-12.8%), ethanol (15.4-28.8%), and hydrogen (4.0-8.1%), with lesser amounts of acetone, propanol, and butanol (COD basis). Hydrogen gas phase concentrations in all batch cultures reached a maximum of 57-72% after 30 h but thereafter rapidly declined to nondetectable levels within 80 h. Separate experiments showed substantial hydrogen losses could occur via acetogenesis and that heat treatment did not prevent acetogenesis. Heat treatment consistently eliminated the production of measurable concentrations of methane. The disappearance of ethanol produced during hydrogen production was likely due to acetic acid production as thermodynamic calculations show that this reaction is spontaneous once hydrogen is depleted. Overall, these results show that low pH was, without heat treatment, sufficient to control hydrogen losses to methanogens in mixed batch cultures and suggest that methods will need to be found to limit acetogenesis in order to increase hydrogen gas yields by batch cultures.

- by Steven Van Ginkel
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- Environmental Science, Thermodynamics, Hydrogen, Heat Treatment

This paper is directed towards the development of safe, and thermally stable solid polymer electrolytes. Linear phosphorus-containing (co)polyesters are described, including their synthesis, thermal analysis, conductivity, and non-flammability. Polycondensation of phenylphosphonic dichloride (PPD) with poly(ethylene glycol) (PEG 12000) with and without bisphenol A (BA) was carried out using solid-liquid phase transfer catalysis. Potassium phosphate is used as base. Yields in the range of 85.0-88.0%, and inherent viscosities in the range of 0.32-0.58 dL/g were obtained. The polymers were characterized by gel permeation chromatography, FT-IR, 1 H-and 31 P-NMR spectroscopy and thermal analysis. Their flammability was investigated by measuring limiting oxygen index values. The polymers are flame retardants and begin to lose weight in the 190 °C-231 °C range. Solid phosphorus-containing (co)polyesters were complexed with lithium triflate and the resulting ionic conductivity was determined. Conductivities in the range of 10 −7 -10 −8 S cm −1 were obtained.

- by GHEORGHE ILIA
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- Thermodynamics, Organic Chemistry, Electrochemistry, Catalysis

This paper explores the self-organising principles of horizontally-integrated innovation networks. It is shown that such networks can self-organising in environments where the co-ordination and production of new knowledge is itself a complex, dynamic and highly non-linear processes. The paper argues the development of a self-organisation perspective of innovation networks has two advantages. First, it provides a general framework of dynamic systems in which different strands of a highly fragmented literature can be drawn together. Second, formal self-organisation modelling techniques can provide interesting new insights into the micro-macro processes driving dynamic innovation systems.

- by Andreas Pyka
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- Thermodynamics, Scientific, Research and Development, Publication
- by Alessandro Ponti and +2
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- Algorithms, Thermodynamics, Magnetic Resonance Spectroscopy, Circular Dichroism

Objective: Biodegradable polycaprolactone/starch composites can be used for bone tissue engineering applications. The effect of the ratio of components on composite properties is of tremendous importance. Methods: Polycaprolactone/starch composite of 80/20 and 70/30 ratios were fabricated by dissolving them in chloroform followed by evaporation of the solvent. Results: The composites were characterized by fourier transform infrared spectroscopy. Their bioactivity was evaluated by studying the apatite formation ability after immersing the specimens in simulated body fluid. The results of compressive test on samples showed that the composite's modulus and strength approximated that of human trabecular bone. Mass loss in distilled water and starch degradation rate in PBS was evaluated, which showed that the starch ratio was effective in composite degradation. MTT analysis and alkaline phosphatase levels showed that this composite had no toxicity and could increase G-299 cell line osteoblastic activities. Conclusion: The increase in cellular osteoblastic activities and the ability for apatite formation on the composite surface, in addition to the polycaprolactone/starch samples' mechanical properties shows their capability to be used as substitutes for bone. Because this composite degradation rate is controlled by changing the starch ratio, it has the potential for use in bone tissue engineering applications. Samples that have a 70/30 ratio are considered optimal due to their enhanced cellular response and better mechanical properties.

- by Mehran Solati-Hashjin
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- Engineering, Materials Engineering, Chemical Engineering, Thermodynamics

ABSTRACT A Green-function method is employed within a random phase approximation to study the one-dimensional quantum Heisenberg model with long-range ferromagnetic interaction proportional to r-p. We have shown that for... more

- by N. Benzakour
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- Thermodynamics, Phase transition, Specific Heat, Spin Wave

Type 316L stainless steel (316L SS), commonly used as pot roll material, was tested in an industrial Zn-Al galvanizing bath, with an effective Al content of 0.2 wt.%. Samples welded to the supporting roll arms and sides of the sink roll experienced heavy dross buildup. Samples placed at locations away from the incoming strip generally experienced much less dross buildup. Dross particles within the buildup on samples attached to supporting roll arms were small in size but numerous while particles on samples welded to the sides of the sink roll were much larger. SEM-EDS analyses indicated that the buildup consisted of two layers. The inner layer was the product of the corrosive reaction of 316L SS with the bath metal, and the outer layer was formed by dross particles built up on the inner reaction layer. The intermetallic phase, which formed at the reaction front of the samples was the inhibition compound Fe 2 Al 5 containing some Mo and Cr. The formation of this intermetallic layer provided a thermodynamically favourable base for the attachment and further buildup of suspended dross particles on the sample surfaces.

- by Frank Goodwin
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- Engineering, Materials Science, Thermodynamics, Metallurgy

We report here a robust automated active site detection, docking, and scoring (AADS) protocol for proteins with known structures. The active site finder identifies all cavities in a protein and scores them based on the physicochemical properties of functional groups lining the cavities in the protein. The accuracy realized on 620 proteins with sizes ranging from 100 to 600 amino acids with known drug active sites is 100% when the top ten cavity points are considered. These top ten cavity points identified are then submitted for an automated docking of an input ligand/candidate molecule. The docking protocol uses an all atom energy based Monte Carlo method. Eight low energy docked structures corresponding to different locations and orientations of the candidate molecule are stored at each cavity point giving 80 docked structures overall which are then ranked using an effective free energy function and top five structures are selected. The predicted structure and energetics of the complexes agree quite well with experiment when tested on a data set of 170 proteinÀligand complexes with known structures and binding affinities. The AADS methodology is implemented on an 80 processor cluster and presented as a freely accessible, easy to use tool at http://www.scfbio-iitd.res.in/ dock/ActiveSite_new.jsp.

- by Tanya Singh
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- Computer Science, Algorithms, Thermodynamics, Chemistry
- by Riccardo Rigon
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- Thermodynamics, Chemistry, Porous Medium

The interaction of leech-derived tryptase inhibitor (LDTI) with bovine liver capsule tryptase (BLCT) and bovine trypsin has been studied using both thermo-dynamic and kinetic approaches. Several differences were detected: (i) the equilibrium affinity of LDTI for BLCT (Ka = 8.9 105 M–1) is about 600-fold lower than that for bovine trypsin (Ka = 5.1 108 M–1); (ii) LDTI be-haves as a purely non-competitive inhibitor of BLCT, while it is a purely competitive inhibitor of bovine tryp-sin. These functional data are compared with those previously reported for the LDTI binding to human tryptase, where tight inhibition occurs at two of the four active sites of the tetramer (Ka = 7.1 108 M–1). Amino acid sequence alignment of BLCT, human II-tryptase and bovine trypsin allows us to infer some possible structural basis for the observed functional differences.

- by Fulvio Erba
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- Thermodynamics, Kinetics, Biological Chemistry, Trypsin

AbstractThis paper reports on the control structure of the pneumatic biped Lucy. The robot is actuated with pleated pneumatic artificial muscles, which have interesting characteristics that can be exploited for legged machines. They have... more

- by ronald van ham
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- Thermodynamics, Dynamic control, Qualitative evaluation, Dynamic Simulation

A thermodynamic equilibrium analysis on the multi-reaction system for carbon dioxide reforming of methane in view of carbon formation was performed with Aspen plus based on direct minimization of Gibbs free energy method. The effects of CO 2 /CH 4 ratio (0.5–3), reaction temperature (573–1473 K) and pressure (1–25 atm) on equilibrium conversions, product compositions and solid carbon were studied. Numerical analysis revealed that the optimal working conditions for syngas production in Fischer–Tropsch synthesis were at temperatures higher than 1173 K for CO 2 /CH 4 ratio being 1 at which about 4 mol of syngas (H 2 /CO = 1) could be produced from 2 mol of reactants with negligible amount of carbon formation. Although temperatures above 973 K had suppressed the carbon formation, the moles of water formed increased especially at higher CO 2 /CH 4 ratios (being 2 and 3). The increment could be attributed to RWGS reaction attested by the enhanced number of CO moles, declined H 2 moles and...

- by mohammad jafarbegloo
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- Chemical Engineering, Thermodynamics, Carbon Dioxide, Numerical Analysis
- by John Markley
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- Relational Database, Information Retrieval, Thermodynamics, Chemistry

The adsorption properties of pyridine on H-ZSM-5 zeolites have been investigated by cluster calculations with the ONIOM scheme and with an embedded-ONIOM scheme. The active site has been modeled with cluster sizes of up to 46 tetrahedra. Two different types of pyridine adsorption complexes on the zeolite models are found. If Zeolite is modeled by a small 3T quantum cluster, the adsorption energy of the hydrogen-bonded pyridine complex (Py-Hz), is found to be À18.5 kcal/mol. When a larger cluster or the ONIOM models are employed, the optimized geometries show the formation of pyrdinium cation [PyH + ] bound as an ion-pair complex [PyH + ][Z À ]. The calculated energy of formation for this ion-pair complex is À36.8 kcal/mol in the ONIOM (B3LYP/6-31G(d,p):UFF) model. Both values are considerably lower than the experimentally estimated heat of adsorption of pyridine in ZSM-5 zeolite of À47.6 kcal/mol. Inclusion of the electrostatic effects of the zeolite crystal lattice via the embedded ONIOM model increases the adsorption energy to À44.4 kcal/mol. Performing the quantum-chemical treatment at the MP2/6-31G(d,p) level instead of the B3LYP/6-31G(d,p) leads to a slightly lower adsorption energy to À45.9 kcal/mol. These data suggest that the embedded ONIOM scheme provides an accurate method of studying the interaction of small organic molecules with zeolites.

- by Jarun Lomratsiri
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- Thermodynamics, Adsorption, Zeolites, Computer Software

A simple climate model has been developed to investigate the existence of the small ice cap instability in the Southern Hemisphere. The model consists of four coupled components: an atmospheric energy balance model, a thermodynamic snow-sea ice model, an oceanic mixed layer model and a terrestrial ice model. Results from a series of experiments involving different degrees of coupling in the model show that the instability appears only in those cases when an explicit representation of the Antarctic ice sheet is not included in the model. In order to determine which physical processes in the ice sheet model lead to a stabilization of the system we have conducted several sensitivity experiments in each of which a given ice sheet process has been removed from the control formulation of the model. Results from these experiments suggest that the feedback between the elevation of the ice sheet and the snow accumulation-ice ablation balance is responsible for the disappearance of the small ice cap instability in our simulation. In the model, the mass balance of the ice sheet depends on the air temperature at sea level corrected for altitude and it is, therefore, a function of surface elevation. This altitudemass balance feedback effectively decouples the location of the ice edge from any specific sea level isotherm, thus decreasing the model sensitivity to the albedotemperature feedback, which is responsible for the appearance of the instability. It is also shown that M. A. Morales Maqueda ()) A

- by Miguel Angel Morales Maqueda
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- Oceanography, Thermodynamics, Sea Level, Sea Ice

Thermodynamics of the hydrophobic effect in su rfact a n t sol u t ions-m ice1 I ization and adsorption

- by Rebecca Silveston-Keith
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- Engineering, Thermodynamics, Physical sciences, CHEMICAL SCIENCES

Like our previous work with imidazolium-and phosphonium-based ionic liquids, we report diffusivities over a range of viscosities (71-532 cP) and develop a predictive diffusivity correlation. Reported are the permeability, solubility, and diffusivity data for nine gases in nine ammonium RTILs liquids at 30 • C, as determined with a lag-time technique. The gas solubilities and diffusivities of the ammonium RTILs are of the same magnitude as those for the phosphonium and imidazolium RTILs. The ammonium RTILs used, in this study, included cations with both N-alkyl groups and branched alkyl groups. We also report on ammonium-based RTILs derived from quaternary ammonium surfactants. These surfactantsderived ammonium-based RTILs offer a relatively inexpensive alternative to imidazolium-based RTILs. We compare and contrast the thermodynamic (solubility) and transport (diffusivities) phenomena in the ammonium-based RTILs with both the imidazolium and the phosphonium RTILs in the context of being working fluids in a chemical process. From this comparison came certain "universal" trends for diffusivity in RTILs. Specifically, diffusivity scales roughly with the inverse of the square-root of viscosity and inversely with solute molar volume to the power of 1-1.3. This means that diffusivity, in RTILs, is less dependent on viscosity, and more dependent on solute size than predicted by the conventional Stokes-Einstein model. The gases tested were carbon dioxide, nitrogen, oxygen, methane, ethylene, propylene, 1-butene, butane, and 1,3-butadiene.

- by Paul Scovazzo
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- Chemical Engineering, Thermodynamics, Carbon Dioxide, Modeling

The phonon densities of states (DOS) of insulating BaBi03 and superconducting Bap 6Kp 4Bi03 and the variation of the phonon spectrum of the superconducting compound upon oxygen-isotope (' 0, ' 0) substitution are determined by inelastic neutron scattering (INS) and molecular-dynamics (MD) simulations. The MD simulations are carried out with an effective interaction potential which includes steric effects, Coulomb interactions, and the charge-dipole interactions due to the electronic polarizability of 0 The MD results are in good agreement with the INS experiments and electron-tunneling measurements. Partial DOS of Ba, K, Bi, and 0 in BaBi03 and Bap 6Kp 4Bi03 are also determined from MD simulations. In the superconducting material, the phonon spectrum softens and is comprised of broad bands around 15, 30, and 60 meV. The partial DOS reveal that phonons above 20 meV are due to oxygen vibrations, whereas phonons below 20 meV are due to Ba, K, and Bi. The reference oxygen-isotope-effect exponent, ao, =-t}ln(cp)/t)lnMo, of Bap 6Kp 4BiO, is determined to be ao"=0. 42+0.05 from the mass (Mo) 16O 180 variation of the first moment of the phonon DOS, (cp) and c(cp). This value is close to the oxygenisotope-effect exponent, ao, determined from the variation of T, (0.41+0.03 by Hinks et al. and 0.35+0.05 by Kondoh et al.), indicating that Bap 6Kp 4BiO, is a weak-to moderate-coupling BCS-like superconductor and that the high T, (-30 K) results from large electron-phonon matrix elements involving high-energy oxygen-related phonons.

- by Marcos Degani
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- Thermodynamics, Inelastic Neutron Scattering, Superconductors, Alkali Metals

Experimental and theoretical flux models have been developed to reveal the influence of sun flecks and increasing CO 2 concentrations on the energy and entropy balances of the leaf. The rapid and wide range of fluctuations in light intensity under field conditions were simulated in a climatic gas exchange chamber and we determined the energy and entropy balance of the leaf based on radiation and gas exchange measurements. It was estimated that the energy of photosynthetic active radiation (PAR) accounts for half of transpiration, which is the main factor responsible for the exportation of the entropy generated in photosynthesis (S g) out of the leaf in order to maintain functional the photosynthetic machinery. Although the response of net photosynthetic production to increasing concentrations of CO 2 under fluctuating light is similar to that under continuous light, rates of transpiration respond slowly to changes of light intensity and are barely affected by the concentration of CO 2 in the range of 260-495 ppm, in which net photosynthesis increases by more than 100%. The analysis of the results confirms that future increases of CO 2 will improve the efficiency of the conversion of radiant energy into biomass, but will not reduce the contribution of plant transpiration to the leaf thermal balance.

- by Dolores Marín
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- Engineering, Thermodynamics, Carbon Dioxide, Photosynthesis

Background: The effectiveness of aerosol therapy is significantly reduced by the mucus layer covering the airways of the tracheobronchial tree. According to the present concept, drug particles are delivered to the lung together with the functional carrier particle that facilitates both the drug transport into the lungs and the penetration of deposited particles through the mucus. The approach of manufacturing multicomponent powders with mucoactive compounds and anti-asthmatic medicines (DSCG) bound together in a single particle is additionally considered. Methods: Powders were produced with the spray-drying technique from aqueous precursor solutions containing pure low molecular weight dextran, pure mannitol and dextran/mannitol-N-acetyl cysteine (NAC) mixtures (4:1 and 1:1). NAC has been selected for this purpose as a compound, which is known to be mucolytic. Dextran and mannitol are potentially applicable in the field of inhalation drug delivery. They have been used as stabilizers of functional carrier particles. Powders were characterized for their yield and physicochemical properties including: morphology (SEM), moisture content and thermal properties (DSC). Aerosol performance was determined with NGI impactor after standardized aerosolization of the produced powders in a commercial DPI. Results: Particle size distributions of dextran-NAC powders were characterized by high fine particle fraction (45-62%), which assures good particle deposition in the lower airways. The thermodynamic properties of the powders based on the temperature of the glass transition T g (50-63 • C) suggest the required stability during storage at moderate humidity. Conclusions: Preliminary examination of the required properties of these particles confirms their potential as functional carriers for pulmonary drug delivery.

- by Tomasz Sosnowski
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- Thermodynamics, Scanning Electron Microscopy, Aerosols, Pharmaceutics

Density Functional calculations have proven to be a powerful tool to study the ground state of many materials. For finite temperatures the situation is less ideal and one is often forced to rely on models with parameters either fitted to zero temperature first principles calculations or experimental results. This approach is especially unsatisfactory in inhomogeneous systems, nano particles, or other systems where the model parameters could vary significantly from one site to another. Here we describe a possible solution to this problem by combining classical Monte Carlo calculations-the Wang-Landau method[2] in this case-with a firs principles electronic structure calculation, specifically our locally selfconsistent multiple scattering code (LSMS)[3]. The combined code shows superb scaling behavior on massively parallel computers. The code sustained 1.836 Petaflop/s on 223,232 cores of the Cray XT5 jaguar system at Oak Ridge.

- by Donald Nicholson
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- Thermodynamics, Monte Carlo, Parallel Processing, Density-functional theory

meso-Tetraphenylporphyrin N-oxide (1) and meso-tetraphenyl-21,23-dithiaporphyrin S-oxide (3) possess optical spectra that are distinctly different from their parent porphyrins, meso-tetraphenylporphyrin (2) and meso-tetraphenyl-21,23-dithiaporphyrin (4), respectively. The hyperporphyrin spectra were reproduced and classified using TD CAM-B3LYP and SCS-CC2 computational methods. Calculations revealed the electronic and conformational influences of the N- and S-oxide functionalities. While the N-oxide under acidic conditions forms a dication with a UV-vis spectrum that is nearly indistinguishable from that of the diprotonated parent porphyrin, the diprotonated S-oxide possesses a much different UV-vis spectrum from diprotonated parent dithiaporphyrin. A computational study of the protonation events revealed the site and degree of protonation and rationalized the regular and hyperporphyrin UV-vis spectra of the neutral and protonated species, respectively. The study illuminates the ele...

- by Torsten Bruhn
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- Thermodynamics, Quantum Theory, Porphyrins, Physical sciences

The biosorption of food dyes FD&C red no. 40 and acid blue 9 onto Spirulina platensis nanoparticles was studied at different conditions of pH and temperature. Four isotherm models were used to evaluate the biosorption equilibrium and the thermodynamic parameters were estimated. Infra red analysis (FT-IR) and energy dispersive X-ray spectroscopy (EDS) were used to verify the biosorption behavior. The maximum biosorption capacities of FD&C red no. 40 and acid blue 9 were found at pH 4 and 298 K, and the values were 468.7 mg g À1 and 1619.4 mg g À1 , respectively. The Sips model was more adequate to fit the equilibrium experimental data (R 2 > 0.99 and ARE < 5%). Thermodynamic study showed that the biosorption was exothermic, spontaneous and favorable. FT-IR and EDS analysis suggested that at pH 4 and 298 K, the biosorption of both dyes onto nanoparticles occurred by chemisorption.

- by Luiz Pinto and +1
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- Thermodynamics, Nanoparticles, Multidisciplinary, Adsorption

Background: 1E10 monoclonal antibody is a murine anti-idiotypic antibody that mimics N-glycolyl-GM3 gangliosides. This antibody has been tested as an anti-idiotypic cancer vaccine, adjuvated in Al(OH) 3 , in several clinical trials for melanoma, breast, and lung cancer. During early clinical development this mAb was obtained in vivo from mice ascites fluid. Currently, the production process of 1E10 is being transferred from the in vivo to a bioreactor-based method.

- by Adolfo Castillo
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- Engineering, Thermodynamics, Organic Chemistry, Physical Chemistry

Several approaches to the matter creation problem in the context of cosmological models are summarily reviewed. A covariant formulation of the general relativistic imperfect simple fluid endowed with a process of matter creation is presented. By considering the standard big bang model, it is shown how the recent results of Prigogine et alii \cite{1} can be recovered and, at the same time their limits of validity are explicited.

- by Mauricio Calvao
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- Thermodynamics, Big Bang

The constructal law of generation of flow structure is used to predict the main features of global circulation and climate. The flow structure is the atmospheric and oceanic circulation. This feature is modelled as convection loops, and added to the earth model as a heat engine heated by the Sun and cooled by the background. It is shown that the dissipation of the power produced by the earth engine can be maximized by selecting the proper balance between the hot and cold zones of the Earth, and by optimizing the thermal conductance of the circulation loops. The optimized features agree with the main characteristics of global circulation and climate. The robustness of these predictions, and the place of the constructal law as a selfstanding principle in thermodynamics, are discussed.

- by Antonio Heitor Reis
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- Mechanical Engineering, Chemical Engineering, Earth Sciences, Geophysics

In the present paper an attempt has been made for the comparative study of different equations of state for silicon (Phase-1, cubic diamond structure) in the pressure range of 0-11 GPa. We compare the results of different equations of state (EOS) with available experimental data. The Kwon and Kim EOS is found to give far better agreement with the available experimental data. Results obtained by Poirier-Tarantola, Vinet, Tait and Suzuki's equations of state are not giving satisfactory agreement with the available experimental data. In the present study simple methods based on thermodynamic functions are presented to investigate the temperature dependence of thermal expansivity and bulk modulus for silicon. The results are reported for silicon. The calculated values of thermal expansivity are in good agreement with experimental data.

- by Apoorva Bhatt
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- Engineering, Thermodynamics, Physical sciences, Bulk Modulus

It is shown experimentally that the desorption of sodium decyl sulphate from the liquid/air interface is purely diffusion controlled, while the desorption of higher surface active surfactants such as the non-ionic surfactants Triton X-100 and tridecyl dimethyl phosphine oxide obeys a mixed mechanism. The desorption kinetics of β-lactoglobulin (BLG) and β-casein is, however, determined by a barrier mechanism. From the analysis of the BLG and β-casein desorption kinetics at different temperatures the activation energy of desorption is calculated. The values obtained are rather close to the free energy of adsorption. The theoretical model of desorption kinetics predicts that these two energetic parameters are similar if the adsorption activation energy is low. This explains why substances with a higher adsorption activity have a lower desorption rate. Adsorption kinetics studies for β-casein with and without forced convection show the same equilibrium surface tension values. This leads to the conclusion that the protein adsorption at liquid interfaces is thermodynamically reversible, although the slow desorption kinetics would allow to assume it to be an irreversible process.

- by Heribert Watzke
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- Engineering, Thermodynamics, Protein adsorption, Kinetics

This work shows the experimental data of excess properties at several temperatures and the vapor–liquid equilibria (VLE) obtained for four binary systems of alkyl methanoates (methyl to butyl) with decane, all measured at constant pressure of 101.32kPa. The isobaric VLE data were thermodynamically consistent according to the Fredenslund test and did not present an azeotrope. The experimental data of HmE

- by juan ortega
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- Chemical Engineering, Thermodynamics, VLE, Classical Physics