Modelling the structure and function of extracellular polymeric substances in biofilms with new numerical techniques

2001 ◽  
Vol 43 (6) ◽  
pp. 121-127 ◽  
Author(s):  
H. Horn ◽  
T. R. Neu ◽  
M. Wulkow
Keyword(s):  
Extracellular Polymeric Substances ◽  
Volume Fraction ◽  
Structure And Function ◽  
Biofilm Growth ◽  
Biofilm Model ◽  
The Matrix ◽  
Substrate Conversion ◽  
The One ◽  
And Function ◽  
Biofilm Structure

The objective of this study is the mathematical description of the structure and function of the extracellular polymeric substances (EPS) in biofilms. The basic assumptions of the EPS biofilm model are:the production of EPS in biofilms is coupled to the growth of micro-organismsthe production of EPS is additionally coupled to the substrate conditions-the EPS represent a considerable volume fraction of the matrix in biofilms and thus the density of the biofilms is strongly influenced by the EPS-sorption of biocides and pollutants in biofilms occurs mainly to EPSthe EPS can be used as an energy source during substrate limited phases. The mathematical model has been derived as a system of partial differential equations. The numerical solution of these complex balance equations has been done by a self-adaptive Galerkin-h-p-method. It can be shown, that on the one hand the simulation of substrate conversion and biofilm growth with the EPS-biofilm model yields similar results as the known biofilm models without consideration of the EPS fraction. On the other hand the advantage of the EPS-biofilm model is a better understanding of biofilm structure, which is mainly influenced by the EPS fraction in the biofilm. Furthermore, the sorption of pollutants, such as heavy metals and chlorinated organic substances, can be simulated in more detail.

Effect of EPS on biofilm structure and function as revealed by an individual-based model of biofilm growth

2001 ◽  
Vol 43 (6) ◽  
pp. 135-135 ◽  
Author(s):  
J.-U. Kreft ◽  
J. W. Wimpenny
Keyword(s):  
Dimensional Space ◽  
Three Dimensional ◽  
Structure And Function ◽  
Individual Based Model ◽  
Biofilm Growth ◽  
Rate Dependent ◽  
Binding Forces ◽  
The Individual ◽  
And Function ◽  
Biofilm Structure

We have simulated a nitrifying biofilm with one ammonia and one nitrite oxidising species in order to elucidate the effect of various extracellular polymeric substance (EPS) production scenarios on biofilm structure and function. The individual-based model (IbM) BacSim simulates diffusion of all substrates on a two-dimensional lattice. Each bacterium is individually simulated as a sphere of given size in a continuous, three-dimensional space. EPS production kinetics was described by a growth rate dependent and an independent term (Luedeking-Piret equation). The structure of the biofilm was dramatically influenced by EPS production or capsule formation. EPS production decreased growth of producers and stimulated growth of non-producers because of the energy cost involved. For the same reason, EPS accumulation can fall as its rate of production increases. The patchiness and roughness of the biofilm decreased and the porosity increased due to EPS production. EPS density was maximal in the middle of the vertical profile. Introduction of binding forces between like cells increased clustering.

Preparation of Electron Transparent Metal-Matrix Composites

1968 ◽  
Vol 26 ◽  
pp. 334-335 ◽  
Author(s):  
M. R. Pinnel ◽  
A. Lawley
Keyword(s):  
Stainless Steel ◽  
Load Transfer ◽  
Volume Fraction ◽  
Steel Wire ◽  
Initial Step ◽  
Interfacial Region ◽  
Matrix Composites ◽  
Specific Test ◽  
The Matrix ◽  
The One

Numerous phenomenological descriptions of the mechanical behavior of composite materials have been developed. There is now an urgent need to study and interpret deformation behavior, load transfer, and strain distribution, in terms of micromechanisms at the atomic level. One approach is to characterize dislocation substructure resulting from specific test conditions by the various techniques of transmission electron microscopy. The present paper describes a technique for the preparation of electron transparent composites of aluminum-stainless steel, such that examination of the matrix-fiber (wire), or interfacial region is possible. Dislocation substructures are currently under examination following tensile, compressive, and creep loading. The technique complements and extends the one other study in this area by Hancock.The composite examined was hot-pressed (argon atmosphere) 99.99% aluminum reinforced with 15% volume fraction stainless steel wire (0.006″ dia.).Foils were prepared so that the stainless steel wires run longitudinally in the plane of the specimen i.e. the electron beam is perpendicular to the axes of the wires. The initial step involves cutting slices ∼0.040″ in thickness on a diamond slitting wheel.

scholarly journals Testing the light:nutrient hypothesis: Insights into biofilm structure and function using metatranscriptomics

2018 ◽  
Vol 27 (14) ◽  
pp. 2909-2912 ◽  
Author(s):  
Allison M. Veach ◽  
Natalie A. Griffiths
Keyword(s):  
Structure And Function ◽  
And Function ◽  
Biofilm Structure

scholarly journals The Development of E-Atlas Learning Media Based on Mobile Learning on Cells Structure Material in SMA N 1 Kandangserang

2019 ◽  
Vol 8 (1) ◽  
pp. 15-25
Author(s):  
Diah Agung Setiawati ◽  
Ning Setiati ◽  
Tyas Agung Pribadi
Keyword(s):  
Learning Outcomes ◽  
Mobile Learning ◽  
Cell Structure ◽  
Structure And Function ◽  
Sampling Techniques ◽  
The Media ◽  
The One ◽  
Teaching Learning ◽  
And Function ◽  
Academic Year

Cells are the one of hard-to-understand material for students, because it cannot be seen directly by students therefore it requires detailed visualization of images to explain the structure and processes that occur in it. Adequate visualization is needed to study better the structure and function of cells. This is the reason why we need to develop a mobile learning media. The media is an E-atlas of cell structure and function. This product is then analyzed its suitability as a learning media in SMA N 1 Kandangserang. Students of classes XI MIA 1 and XI MIA 2 academic year 2018/2019 were selected as the samples of this research using saturated sampling techniques. This is a research and development (R & D). Research shows that E-atlas is suitable as learning media. E-atlas affects the learning outcomes, where the N-gain value shows an increase with an average of 0.72 (categorized as high) with classical completeness of 83%. It is concluded that E-atlas mobile learning is suitable as a teaching learning medium for students.

scholarly journals Universal rules of life: metabolic rates, biological times and the equal fitness paradigm

2021 ◽  
Author(s):  
Joseph Burger ◽  
Chen Hou ◽  
Charles Hall ◽  
James Brown
Keyword(s):  
Structure And Function ◽  
The Other ◽  
Metabolic Rates ◽  
Synthetic Theory ◽  
Evolutionary Patterns ◽  
Single Origin ◽  
The One ◽  
Patterns And Processes ◽  
And Function ◽  
Dynamics Of Populations

Here we review and extend the equal fitness paradigm (EFP) as an important step in developing and testing a synthetic theory of ecology and evolution based on energy and metabolism. The EFP states that all organisms are equally fit at steady state, because they allocate the same quantity of energy, ~22.4 kJ/g/generation to production of offspring. On the one hand, the EFP may seem tautological, because equal fitness is necessary for the origin and persistence of biodiversity. On the other hand, the EFP reflects universal laws of life: how biological metabolism – the uptake, transformation and allocation of energy – links ecological and evolutionary patterns and processes across levels of organization from: i) structure and function of individual organisms, ii) life history and dynamics of populations, iii) interactions and coevolution of species in ecosystems. The physics and biology of metabolism have facilitated the evolution of millions of species with idiosyncratic anatomy, physiology, behavior and ecology but also with many shared traits and tradeoffs that reflect the single origin and universal rules of life.

The musculoskeletal system: structure and function

2011 ◽  
Author(s):  
Parminder J. Singh ◽  
Rohit Kotnis
Keyword(s):  
Composite Material ◽  
Bone Formation ◽  
Blood Supply ◽  
Musculoskeletal System ◽  
Endochondral Ossification ◽  
Structure And Function ◽  
System Structure ◽  
Inorganic Component ◽  
The Matrix ◽  
And Function

♦ Structure of bone is comprised of cells, matrix, and water♦ Bone consists broadly of three surfaces (periosteal, endosteal, and Haversian) and two membranes (periosteum and endosteum)♦ The blood supply of bone is derived from four main routes (nutrient, metaphyseal, epiphyseal, and periosteal arteries)♦ There are three main types of cells in bone (osteoblast, osteocyte, and osteoclast)♦ The matrix is a composite material consisting of an organic and an inorganic component♦ Two types of bone formation are intramembranous and endochondral ossification♦ The skeleton is also involved in the vital homeostasis of calcium and phosphate.

scholarly journals Structure and Function of 4-Hydroxyphenylacetate Decarboxylase and Its Cognate Activating Enzyme

2016 ◽  
Vol 26 (1-3) ◽  
pp. 76-91 ◽  
Author(s):  
Brinda Selvaraj ◽  
Wolfgang Buckel ◽  
Bernard T. Golding ◽  
G. Matthias Ullmann ◽  
Berta M. Martins
Keyword(s):  
Small Subunit ◽  
Structure And Function ◽  
Binding Motif ◽  
Prosthetic Group ◽  
New Class ◽  
Glycyl Radical ◽  
Open Questions ◽  
Substrate Conversion ◽  
And Function ◽  
A Site

4-Hydroxyphenylacetate decarboxylase (4Hpad) is the prototype of a new class of Fe-S cluster-dependent glycyl radical enzymes (Fe-S GREs) acting on aromatic compounds. The two-enzyme component system comprises a decarboxylase responsible for substrate conversion and a dedicated activating enzyme (4Hpad-AE). The decarboxylase uses a glycyl/thiyl radical dyad to convert 4-hydroxyphenylacetate into <i>p</i>-cresol (4-methylphenol) by a biologically unprecedented Kolbe-type decarboxylation. In addition to the radical dyad prosthetic group, the decarboxylase unit contains two [4Fe-4S] clusters coordinated by an extra small subunit of unknown function. 4Hpad-AE reductively cleaves S-adenosylmethionine (SAM or AdoMet) at a site-differentiated [4Fe-4S]<sup>2+/+</sup> cluster (RS cluster) generating a transient 5′-deoxyadenosyl radical that produces a stable glycyl radical in the decarboxylase by the abstraction of a hydrogen atom. 4Hpad-AE binds up to two auxiliary [4Fe-4S] clusters coordinated by a ferredoxin-like insert that is C-terminal to the RS cluster-binding motif. The ferredoxin-like domain with its two auxiliary clusters is not vital for SAM-dependent glycyl radical formation in the decarboxylase, but facilitates a longer lifetime for the radical. This review describes the 4Hpad and cognate AE families and focuses on the recent advances and open questions concerning the structure, function and mechanism of this novel Fe-S-dependent class of GREs.

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