scholarly journals Enzymic Approach to Eurythermalism of Alvinella pompejana and Its Episymbionts

2007 ◽  
Vol 74 (3) ◽  
pp. 774-782 ◽  
Author(s):  
Charles K. Lee ◽  
S. Craig Cary ◽  
Alison E. Murray ◽  
Roy M. Daniel
Keyword(s):  
Equilibrium Model ◽  
Enzyme Stability ◽  
Active Form ◽  
Thermal Adaptation ◽  
Thermal Characteristics ◽  
Dorsal Surface ◽  
Thermal Conditions ◽  
Temperature Adaptation ◽  
Model Parameters ◽  
Alvinella Pompejana

ABSTRACT The equilibrium model, which describes the influence of temperature on enzyme activity, has been established as a valid and useful tool for characterizing enzyme eurythermalism and thermophily. By introducing K eq, a temperature-dependent equilibrium constant for the interconversion between Eact, the active form of enzyme, and Einact, a reversibly inactive form of enzyme, the equilibrium model currently provides the most complete description of the enzyme-temperature relationship; its derived parameters are intrinsic and apparently universal and, being derived under reaction conditions, potentially have physiological significance. One of these parameters, T eq, correlates with host growth temperature better than enzyme stability does. The vent-dwelling annelid Alvinella pompejana has been reported as an extremely eurythermal organism, and the symbiotic complex microbial community associated with its dorsal surface is likely to experience similar environmental thermal conditions. The A. pompejana episymbiont community, predominantly composed of epsilonproteobacteria, has been analyzed metagenomically, enabling direct retrieval of genes coding for enzymes suitable for equilibrium model applications. Two such genes, coding for isopropylmalate dehydrogenase and glutamate dehydrogenase, have been isolated from the A. pompejana episymbionts, heterologously expressed, and shown by reverse transcription-quantitative PCR to be actively expressed. The equilibrium model parameters of characterized expression products suggested that enzyme eurythermalism constitutes part of the thermal adaptation strategy employed by the episymbionts. Moreover, the enzymes' thermal characteristics correspond to their predicted physiological roles and the abundance and expression of the corresponding genes. This paper demonstrates the use of the equilibrium model as part of a top-down metagenomic approach to studying temperature adaptation of uncultured organisms.

scholarly journals Generalized second-order slip for unsteady convective flow of a nanofluid: a utilization of Buongiorno’s two-component nonhomogeneous equilibrium model

2020 ◽  
Vol 9 (1) ◽  
pp. 156-168
Author(s):  
Seyed Mahdi Mousavi ◽  
Saeed Dinarvand ◽  
Mohammad Eftekhari Yazdi
Keyword(s):  
Boundary Layer ◽  
Equilibrium Model ◽  
Second Order ◽  
Model Parameters ◽  
Slip Parameter ◽  
Two Phase ◽  
Convective Boundary ◽  
First Order ◽  
Special Cases ◽  
Two Component

AbstractThe unsteady convective boundary layer flow of a nanofluid along a permeable shrinking/stretching plate under suction and second-order slip effects has been developed. Buongiorno’s two-component nonhomogeneous equilibrium model is implemented to take the effects of Brownian motion and thermophoresis into consideration. It can be emphasized that, our two-phase nanofluid model along with slip concentration at the wall shows better physical aspects relative to taking the constant volume concentration at the wall. The similarity transformation method (STM), allows us to reducing nonlinear governing PDEs to nonlinear dimensionless ODEs, before being solved numerically by employing the Keller-box method (KBM). The graphical results portray the effects of model parameters on boundary layer behavior. Moreover, results validation has been demonstrated as the skin friction and the reduced Nusselt number. We understand shrinking plate case is a key factor affecting non-uniqueness of the solutions and the range of the shrinking parameter for which the solution exists, increases with the first order slip parameter, the absolute value of the second order slip parameter as well as the transpiration rate parameter. Besides, the second-order slip at the interface decreases the rate of heat transfer in a nanofluid. Finally, the analysis for no-slip and first-order slip boundary conditions can also be retrieved as special cases of the present model.

scholarly journals Assessment of model validation outcomes of a new recursive spatial equilibrium model for the Greater Beijing

2017 ◽  
Vol 46 (5) ◽  
pp. 805-825 ◽  
Author(s):  
Li Wan ◽  
Ying Jin
Keyword(s):  
Model Validation ◽  
Equilibrium Model ◽  
Expert Assessment ◽  
Model Parameters ◽  
Multiple Time ◽  
Spatial Equilibrium ◽  
Beijing City ◽  
Spatial Equilibrium Model ◽  
Recursive Equilibrium ◽  
Validation Strategy

Robust calibration and validation of applied urban models are prerequisites for their successful, policy-cogent use. This is particularly important today when expert assessment is questioned and closely scrutinized. This paper proposes a new model calibration-validation strategy based on a spatial equilibrium model that incorporates multiple time horizons, such that the predictive capabilities of the model can be empirically tested. The model is implemented for the Greater Beijing city region and the model validation strategy is demonstrated over the Census years 2000 to 2010. Through forward/backward forecasting, the model validation helps to verify the stability of the model parameters as well as the predictive capabilities of the recursive equilibrium framework. The proposed modelling strategy sets a new standard for verifying and validating recursive equilibrium models. We also consider the wider implications of the approach.

scholarly journals The dependence of enzyme activity on temperature: determination and validation of parameters

2007 ◽  
Vol 402 (2) ◽  
pp. 331-337 ◽  
Author(s):  
Michelle E. Peterson ◽  
Roy M. Daniel ◽  
Michael J. Danson ◽  
Robert Eisenthal
Keyword(s):  
Enzyme Activity ◽  
Equilibrium Model ◽  
Thermal Inactivation ◽  
Accurate Determination ◽  
Active Form ◽  
Thermal Parameter ◽  
Temperature Dependent ◽  
Inactive Form ◽  
Dependent Behaviour

Traditionally, the dependence of enzyme activity on temperature has been described by a model consisting of two processes: the catalytic reaction defined by ΔGDaggercat, and irreversible inactivation defined by ΔGDaggerinact. However, such a model does not account for the observed temperature-dependent behaviour of enzymes, and a new model has been developed and validated. This model (the Equilibrium Model) describes a new mechanism by which enzymes lose activity at high temperatures, by including an inactive form of the enzyme (Einact) that is in reversible equilibrium with the active form (Eact); it is the inactive form that undergoes irreversible thermal inactivation to the thermally denatured state. This equilibrium is described by an equilibrium constant whose temperature-dependence is characterized in terms of the enthalpy of the equilibrium, ΔHeq, and a new thermal parameter, Teq, which is the temperature at which the concentrations of Eact and Einact are equal; Teq may therefore be regarded as the thermal equivalent of Km. Characterization of an enzyme with respect to its temperature-dependent behaviour must therefore include a determination of these intrinsic properties. The Equilibrium Model has major implications for enzymology, biotechnology and understanding the evolution of enzymes. The present study presents a new direct data-fitting method based on fitting progress curves directly to the Equilibrium Model, and assesses the robustness of this procedure and the effect of assay data on the accurate determination of Teq and its associated parameters. It also describes simpler experimental methods for their determination than have been previously available, including those required for the application of the Equilibrium Model to non-ideal enzyme reactions.

scholarly journals Thermographic Analysis of Joints of Supporting Structures

2021 ◽  
Vol 51 (1) ◽  
pp. 94-103
Author(s):  
Laima Skridailaitė ◽  
Loreta Kelpšienė ◽  
Edita Mockienė
Keyword(s):  
Theoretical Calculations ◽  
Thermal Characteristic ◽  
Thermal Characteristics ◽  
Residential Building ◽  
Thermal Conditions ◽  
Energy Class ◽  
Thermographic Analysis ◽  
Residential House ◽  
Building Walls ◽  
The Heat Transfer Coefficient

The external partitions of a building (walls, roof, etc.) in addition to their supporting functions must also ensure an internal microclimate suitable for comfortable human work, recreation and other activities. This article analyzes the thermal characteristics of the external walls of a residential house and thermographically examines the joints of the different structures of the building. Thermographical examination may be performed either passively or actively. In the former case, the object of the examination ir heated up to a given temperature, after which thermographical images of the object are taken and analyzed. In the latter case, thermographical analysis is made of the object in its naturally established thermal conditions. This article examines the thermal characteristics of the partition structures of a residential building. The values of the thermal properties of the materials are taken from the documentation provided by their manufacturers, and in their absence, the data of the technical building regulations is used. Calculated analytically: the wall of the western annex only meets the C energy class requirements, the insulation of the old part of the building raised the heat transfer coefficient of the partition to class A, the thermal characteristic of the eastern annex wall corresponds to the A + energy class. This thermographic examination showed that the facade covered by the fibrous cement siding absorbed less heat compared to the masonry facades. Based on theoretical calculations and the thermographic analysis, it is recommended to additionally insulate the western annex from the inside. If possible, it is also recommended to additionally insulate both facade joints with polyurethane foam and to seal them with waterproofing mastic to prevent the sunrays from reaching the foam.

scholarly journals Patterns of thermal adaptation in a worldwide plant pathogen: local diversity and plasticity reveal two-tier dynamics

2019 ◽  
Author(s):  
Anne-Lise Boixel ◽  
Michaël Chelle ◽  
Frédéric Suffert
Keyword(s):  
Plant Pathogen ◽  
Natural Populations ◽  
Thermal Adaptation ◽  
Thermal Conditions ◽  
List Type ◽  
Zymoseptoria Tritici ◽  
Local Conditions ◽  
Temperature Conditions ◽  
Spatiotemporal Scales ◽  
Pathogen Populations

SummaryPlant pathogen populations inhabit patchy environments with contrasting, variable thermal conditions. We investigated the diversity of thermal responses in populations sampled over contrasting spatiotemporal scales, to improve our understanding of their dynamics of adaptation to local conditions.Samples of natural populations of the wheat pathogen Zymoseptoria tritici were collected from sites within the Euro-Mediterranean region subject to a broad range of environmental conditions. We tested for local adaptation, by accounting for the diversity of responses at the individual and population levels on the basis of key thermal performance curve parameters and ‘thermotype’ (groups of individuals with similar thermal responses) composition.The characterisation of phenotypic responses and genotypic structure revealed: (i) a high degree of individual plasticity and variation in sensitivity to temperature conditions across spatiotemporal scales and populations; (ii) geographic adaptation to local mean temperature conditions, with major alterations due to seasonal patterns over the wheat-growing season.The seasonal shifts in functional composition suggest that populations are locally structured by selection, contributing to shape adaptation patterns. Further studies combining selection experiments and modelling are required to determine how functional group selection drives population dynamics and adaptive potential in response to thermal heterogeneity.

scholarly journals Modelling of wood chips gasification process in ASPEN Plus with multiple validation approach

2019 ◽  
Vol 25 (3) ◽  
pp. 217-228
Author(s):  
Ivana Cekovic ◽  
Nebojsa Manic ◽  
Dragoslava Stojiljkovic ◽  
Marta Trninic ◽  
Dusan Todorovic ◽  
...  
Keyword(s):  
Experimental Work ◽  
Equilibrium Model ◽  
Beech Wood ◽  
Aspen Plus ◽  
Model Verification ◽  
Wood Chips ◽  
Small Scale ◽  
Model Parameters ◽  
Producer Gas ◽  
Heating Value

A thermochemical equilibrium model is formulated for wood chips downdraft gasification. Steady state ASPEN Plus simulator was utilized to evaluate producer gas composition and low heating value. Three cases are considered, due to mathematical model developed issues, and described in details. Experimental work was carried out within commercial small-scale CHP system where twelve beech wood samples were taken. Equivalence ratio is between 0.32 and 0.38 and air-fuel ratio ranges from 1.49 to 1.81, when gasifier capacity is optimal, at 250 kW. Mole fractions of CO2, H2, CO, CH4 and N2, in dry producer gas, are respectively, 16.06-17.64, 17.98-20.33, 13.71-17.26, 1.65-2.89 and 43.21-48.36. Multiple validation approach was applied for model verification. The results are in reasonable agreement with different literature sources (experimental work and modeling) and in a great agreement with the modified equilibrium model developed in Engineering Equation Solver found in the literature. Result deviations are explained by two major facts: wood downdraft gasification experiments are to a certain extent different and the model parameters could not be adjusted enough to fully minimize differences between model results. Predicted low heating value of dry producer gas is between 4.67-5.61 MJ/Nm3.

GAME MODEL FOR ONLINE AND OFFLINE RETAILERS UNDER BUY-ONLINE AND PICK-UP-IN-STORE MODE WITH DELIVERY COST AND RANDOM DEMAND

2020 ◽  
Vol 62 (1) ◽  
pp. 62-88
Author(s):  
YING OUYANG ◽  
ZHAOMAN WAN ◽  
ZHONG WAN
Keyword(s):  
Equilibrium Model ◽  
Optimal Allocation ◽  
Incentive Compatibility ◽  
Consumer Surplus ◽  
Equilibrium Strategy ◽  
Model Parameters ◽  
Game Model ◽  
Selling Price ◽  
Loss Ratio ◽  
Online Retailer

Online retailers are increasingly adding buy-online and pick-up-in-store (BOPS) modes to order fulfilment. In this paper, we study a system of BOPS by developing a stochastic Nash equilibrium model with incentive compatibility constraints, where the online retailer seeks optimal online sale prices and an optimal delivery schedule in an order cycle, and the offline retailer pursues a maximal rate of sharing the profit owing to the consignment from the online retailer. By an expectation method and optimality conditions, the equilibrium model is first transformed into a system of constrained nonlinear equations. Then, by a case study and sensitivity analysis, the model is validated and the following practical insights are revealed. (I) Our method can reliably provide an equilibrium strategy for the online and offline retailers under BOPS mode, including the optimal online selling price, the optimal delivery schedule, the optimal inventory and the optimal allocation of profits. (II) Different model parameters, such as operational cost, price sensitivity coefficient, cross-sale factor, opportunity loss ratio and loss ratio of unsold goods, generate distinct impacts on the equilibrium solution and the profits of the BOPS system. (III) Optimization of the delivery schedule can generate greater consumer surplus, and makes the offline retailer share less sale profit from the online retailer, even if the total profit of the BOPS system becomes higher. (IV) Inventory subsidy is an indispensable factor to improve the applicability of the game model in BOPS mode.

scholarly journals Characterization of a Novel Spirochete Associated with the Hydrothermal Vent Polychaete Annelid, Alvinella pompejana

2001 ◽  
Vol 67 (1) ◽  
pp. 110-117 ◽  
Author(s):  
Barbara J. Campbell ◽  
S. Craig Cary
Keyword(s):  
High Temperature ◽  
Hydrothermal Vent ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Pcr Amplification ◽  
Dorsal Surface ◽  
Specific Primers ◽  
Gradient Gel Electrophoresis ◽  
Polychaetous Annelid ◽  
Alvinella Pompejana

ABSTRACT A highly integrated, morphologically diverse bacterial community is associated with the dorsal surface of Alvinella pompejana, a polychaetous annelid that inhabits active high-temperature deep-sea hydrothermal vent sites along the East Pacific Rise (EPR). Analysis of a previously prepared bacterial 16S ribosomal DNA (rDNA) library identified a spirochete most closely related to an endosymbiont of the oligochete Olavius loisae. This spirochete phylotype (spirochete A) comprised only 2.2% of the 16S rDNA clone library but appeared to be much more dominant when the same sample was analyzed by denaturing gradient gel electrophoresis (DGGE) and the terminal restriction fragment length polymorphism procedure (12 to 18%). PCR amplification of the community with spirochete-specific primers used in conjunction with DGGE analysis identified two spirochete phylotypes. The first spirochete was identical to spirochete A but was present in only one A. pompejana specimen. The second spirochete (spirochete B) was 84.5% similar to spirochete A and, more interestingly, was present in the epibiont communities of all of theA. pompejana specimens sampled throughout the geographic range of the worm (13°N to 32°S along the EPR). The sequence variation of the spirochete B phylotype was less than 3% for the range of A. pompejana specimens tested, suggesting that a single spirochete species was present in the A. pompejanaepibiotic community. Additional analysis of the environments surrounding the worm revealed that spirochetes are a ubiquitous component of high-temperature vents and may play an important role in this unique ecosystem.

Thermal and Optical Analysis of a Stacked Photobioreactor Design

2013 ◽  
Author(s):  
Aadhar Jain ◽  
Erica E. Jung ◽  
Michael Kalontarov ◽  
David Erickson
Keyword(s):  
Thermal Characteristics ◽  
Thermal Conditions ◽  
Close Packing ◽  
Significant Loss ◽  
Design Parameters ◽  
Optical Analysis ◽  
Optimal Range ◽  
Slab Waveguides ◽  
Localized Delivery ◽  
Photobioreactor Design

In this work, we present thermal and optical analysis of a stacked photobioreactor design for growth of fuel producing photosynthetic cyanobacteria to achieve significantly higher volume and energy efficiency as compared to traditional photobioreactor designs. Our photobioreactor design incorporates racks of propagating slab waveguides [1], stacked over each other with spacing of a few hundred microns, in order to optimize light, fluid and gas delivery — the three essential ingredients for cyanobacterial growth — to the cyanobacteria growing in between the racks. The use of propagating slab waveguides provides a mechanism for efficient localized delivery of light to the cyanobacteria. However, it is important to analyze the light distribution of such waveguide systems in the photobioreactors to ensure they always remain within the optimal range for the bacteria. Further, the close packing of cyanobacteria in a closed system raises concerns regarding heat entrapment within the reactor, due to the heat produced as waste by the cyanobacteria. Higher temperatures can lead to a significant loss in efficiency in fuel producing and growth centers of the bacteria. Therefore it is important to design the reactor with appropriate thermal conditions for constraining the temperatures within optimal range for the bacteria. Here we attempt to simulate the thermal characteristics of such a system and estimate the temperature map of the system, and use these to dictate the design parameters and characteristics of the photobioreactor.

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