Anomalous Diffusion in Membranes

1998 ◽  
Vol 543 ◽  
Author(s):  
R. Granek ◽  
S. Pierrat ◽  
A. G. Zilman
Keyword(s):  
Anomalous Diffusion ◽  
Active Sites ◽  
The Other ◽  
Chemical Energy ◽  
Enhanced Diffusion ◽  
Transverse Diffusion

AbstractWe study the undulations and the transverse diffusion of a tagged membrane point in both physical (passive) membranes and active biomembranes. In physical membranes thermal undulations generate a transverse subdiffusive motion, 〈r2〉 ∼ t2/3. Active biomembranes include active sites that use chemical energy to pump ions or molecules from one side to the other. In this case we find a few regimes which show a strongly enhanced diffusion, 〈r2〉 ∼ tα with 1 < α > 2.

scholarly journals Metals in Calluna vulgaris, Empetrum nigrum, Festuca vivipara and Thymus praecox ssp. arcticus in the geothermal areas of Iceland

2021 ◽  
Author(s):  
Adam Rajsz ◽  
Bronisław Wojtuń ◽  
Aleksandra Samecka-Cymerman ◽  
Paweł Wąsowicz ◽  
Lucyna Mróz ◽  
...  
Keyword(s):  
Active Sites ◽  
Calluna Vulgaris ◽  
Bioaccumulation Factor ◽  
The Other ◽  
Extreme Situation ◽  
Empetrum Nigrum ◽  
Geothermal Activity ◽  
High Concentrations ◽  
And Control ◽  
Festuca Vivipara

AbstractThis investigation was conducted to identify the content of metals in Calluna vulgaris (family Ericaceae), Empetrum nigrum (family Ericaceae), Festuca vivipara (family Poaceae) and Thymus praecox subsp. arcticus (family Lamiaceae), as well as in the soils where they were growing in eight geothermal heathlands in Iceland. Investigation into the vegetation of geothermal areas is crucial and may contribute to their proper protection in the future and bring more understanding under what conditions the plants respond to an ecologically more extreme situation. Plants from geothermally active sites were enriched with metals as compared to the same species from non-geothermal control sites (at an average from about 150 m from geothermal activity). The enriched metals consisted of Cd, Co, Cu, Fe and Ni in C. vulgaris; Cd, Mn and Ti in E. nigrum; Hg and Pb in F. vivipara; and Cd, Fe and Hg in T. praecox. Notably, C. vulgaris, E. nigrum, F. vivipara and T. praecox had remarkably high concentrations of Ti at levels typical of toxicity thresholds. Cd and Pb (except for C. vulgaris and F. vivipara) were not accumulated in the shoots of geothermal plants. C. vulgaris from geothermal and control sites was characterised by the highest bioaccumulation factor (BF) of Ti and Mn; E. nigrum and F. vivipara by the highest BF of Ti and Cr; and T. praecox by the highest BF of Ti and Zn compared to the other elements. In comparison with the other examined species, F. vivipara from geothermal sites had the highest concentration of Ti in above-ground parts at any concentration of plant-available Ti in soil.

scholarly journals Caputo Fractional Derivative and Quantum-Like Coherence

Entropy ◽  
2021 ◽  
Vol 23 (2) ◽  
pp. 211
Author(s):  
Garland Culbreth ◽  
Mauro Bologna ◽  
Bruce J. West ◽  
Paolo Grigolini
Keyword(s):  
Diffusion Equation ◽  
Fractional Derivative ◽  
Anomalous Diffusion ◽  
Caputo Fractional Derivative ◽  
Quantum Coherence ◽  
Time Derivative ◽  
The Other ◽  
Diffusion Equations ◽  
Self Organization ◽  
Ordinary Time

We study two forms of anomalous diffusion, one equivalent to replacing the ordinary time derivative of the standard diffusion equation with the Caputo fractional derivative, and the other equivalent to replacing the time independent diffusion coefficient of the standard diffusion equation with a monotonic time dependence. We discuss the joint use of these prescriptions, with a phenomenological method and a theoretical projection method, leading to two apparently different diffusion equations. We prove that the two diffusion equations are equivalent and design a time series that corresponds to the anomalous diffusion equation proposed. We discuss these results in the framework of the growing interest in fractional derivatives and the emergence of cognition in nature. We conclude that the Caputo fractional derivative is a signature of the connection between cognition and self-organization, a form of cognition emergence different from the other source of anomalous diffusion, which is closely related to quantum coherence. We propose a criterion to detect the action of self-organization even in the presence of significant quantum coherence. We argue that statistical analysis of data using diffusion entropy should help the analysis of physiological processes hosting both forms of deviation from ordinary scaling.

scholarly journals Involvement of loop 5 lysine residues and the N-terminal β-hairpin of the ribotoxin hirsutellin A on its insecticidal activity

2016 ◽  
Vol 397 (2) ◽  
pp. 135-145 ◽  
Author(s):  
Miriam Olombrada ◽  
Lucía García-Ortega ◽  
Javier Lacadena ◽  
Mercedes Oñaderra ◽  
José G. Gavilanes ◽  
...  
Keyword(s):  
Active Sites ◽  
Structural Changes ◽  
The Other ◽  
Spatial Proximity ◽  
Ribonucleolytic Activity ◽  
The Family ◽  
Lysine Residues ◽  
Hirsutella Thompsonii ◽  
Close Spatial Proximity ◽  
High Degree

Abstract Ribotoxins are cytotoxic members of the family of fungal extracellular ribonucleases best represented by RNase T1. They share a high degree of sequence identity and a common structural fold, including the geometric arrangement of their active sites. However, ribotoxins are larger, with a well-defined N-terminal β-hairpin, and display longer and positively charged unstructured loops. These structural differences account for their cytotoxic properties. Unexpectedly, the discovery of hirsutellin A (HtA), a ribotoxin produced by the invertebrate pathogen Hirsutella thompsonii, showed how it was possible to accommodate these features into a shorter amino acid sequence. Examination of HtA N-terminal β-hairpin reveals differences in terms of length, charge, and spatial distribution. Consequently, four different HtA mutants were prepared and characterized. One of them was the result of deleting this hairpin [Δ(8-15)] while the other three affected single Lys residues in its close spatial proximity (K115E, K118E, and K123E). The results obtained support the general conclusion that HtA active site would show a high degree of plasticity, being able to accommodate electrostatic and structural changes not suitable for the other previously known larger ribotoxins, as the variants described here only presented small differences in terms of ribonucleolytic activity and cytotoxicity against cultured insect cells.

3D hollow-out TiO2 nanowire cluster/GOx as an ultrasensitive photoelectrochemical glucose biosensor

2020 ◽  
Vol 8 (11) ◽  
pp. 2363-2370 ◽  
Author(s):  
Wenke Yang ◽  
Xiaohong Wang ◽  
Wanjun Hao ◽  
Qiang Wu ◽  
Juan Peng ◽  
...  
Keyword(s):  
Active Sites ◽  
Glucose Biosensor ◽  
Diffusion Effect ◽  
Enhanced Diffusion ◽  
Tio2 Nanowire ◽  
Higher Sensitivity ◽  
Sensitivity Performance

A reticulate TiO2 nanowire cluster electrode demonstrated higher sensitivity performance due to enhanced diffusion effect and more number of active sites.

Impurity Diffusion During RTA

1984 ◽  
Vol 35 ◽  
Author(s):  
R.B. Fair
Keyword(s):  
Anomalous Diffusion ◽  
Solubility Enhancement ◽  
Impurity Diffusion ◽  
High Dose ◽  
Dopant Diffusion ◽  
Enhanced Diffusion ◽  
Intrinsic Diffusivity ◽  
Physical Phenomena ◽  
Induced Dislocation ◽  
Dislocation Formation

ABSTRACTEnhanced dopant diffusion during RTA depends upon whether the following physical phenomena occur individually or in combination: (1) amorphization of the Si, (2) damage-induced dislocation formation, (3) damage annealing, (4) self-interstitial trapping, (5) solubility enhancement. RTA of B in crystalline or preamorphized Si presents significantly different environments for enhanced diffusion. In preamorphized Si, enhanced B diffusion is modeled as increased B solubility following SPE. In addition, a different intrinsic diffusivity is observed which corresponds to B diffusion in preamorphized Si. Anomalous diffusion of B and As from high dose implants can be modeled with the same mechanism -- self-interstitial trapping following SPE.

Analysis of a Model for Anomalous-Diffusion Behavior of CO2 in the Macromolecular-Network Structure of Coal

SPE Journal ◽  
2010 ◽  
Vol 16 (04) ◽  
pp. 856-863 ◽  
Author(s):  
Saikat Mazumder ◽  
Fred Vermolen ◽  
Johannes Bruining
Keyword(s):  
Anomalous Diffusion ◽  
Intermediate Phase ◽  
Time Behavior ◽  
Enhanced Diffusion ◽  
Coal Swelling ◽  
Pure Diffusion ◽  
Macromolecular Network ◽  
Diffusion In Polymers ◽  
Saturation Effects ◽  
Stress Induced Diffusion

Summary This paper gives an analysis of the Thomas and Windle model (Thomas and Windle 1982) to determine its usefulness for describing anomalous diffusion of CO2 in coal and its relation to matrix swelling. In addition, a finite-element description for this model is derived. For reasons of easy reference, a shortened derivation of the Thomas and Windle model is presented, which was originally derived to describe diffusion in polymers. The derivation includes the surface saturation effects proposed by Hui et al. (1987a, 1987b). Because the cumulative sorption showed tα behavior with α &gt; 0.5, the behavior was described as enhanced diffusion or even superdiffusion. Analysis of the model equation shows no evidence for superdiffusion even if non-Fickian behavior is observed [i.e., there is (1) an initial phase in which the coal surface gets saturated with a slope &gt; 0.5 in a log-log plot of cumulative sorption vs. time, (2) an intermediate phase that shows the typical square-root-of-time behavior of an ordinary diffusion process, and (3) a final phase with a slope &lt; 0.5 toward equilibrium]. The cumulative mass is for all times less than what would have been obtained for pure diffusion in a particle characterized by a rubber diffusion coefficient. The slow saturation at the surface masks a process where fast stress-induced diffusion dominates, which indeed can be faster than Fickian. The cumulative sorption rates give behavior similar to the Rückenstein model (Rückenstein et al. 1971), but the advantage of the Thomas and Windle model is that it can also calculate the resulting coal-swelling effects.

scholarly journals Perinatal developmental changes in hepatic UDP-glucuronyltransferase

1980 ◽  
Vol 186 (3) ◽  
pp. 841-845 ◽  
Author(s):  
R B Goldstein ◽  
D A Vessey ◽  
D Zakim ◽  
N Mock ◽  
M Thaler
Keyword(s):  
Kinetic Analysis ◽  
Active Sites ◽  
Glucuronic Acid ◽  
Membrane Lipid ◽  
The Other ◽  
Phospholipase A ◽  
Developmental Changes ◽  
Adult Liver ◽  
Allosteric Effector ◽  
Lipid Environment

Postnatal developmental changes in hapatic microsomal UDP-glucuronyltransferase were studied in the rat. The previously reported postnatal decline in the capacity of microsomal fractions to glucuronidate p-nitrophenol was found to be observable in unperturbed preparations only at non-saturating concentrations of the substrate UDP-glucuronic acid. At saturating concentrations of UDP-glucuronic acid, activity is identical in newborns and adults. Kinetic analysis revealed that the enzyme from liver of newborns has a much higher affinity for UDP-glucuronic acid than does the enzyme in adults, but the same activity at Vmax. On the other hand, the enzyme from adult liver microsomal fractions can be activated by the physiological allosteric effector UDP-N-acetylglucosamine, whereas the enzyme from newborns is largely unaffected by it. Thus it appears that the number of enzyme active sites is not changing; rather, the enzyme is maturing to a more highly regulable form. There were also differences between the enzymes in newborns and adults in their response to perturbation of the membrane-lipid environment by detergent and phospholipase A. Possible interpretations of these differences are discussed.

scholarly journals Control of anomalous diffusion of a Bose polaron

Quantum ◽  
2020 ◽  
Vol 4 ◽  
pp. 232
Author(s):  
Christos Charalambous ◽  
Miguel Ángel García-March ◽  
Gorka Muñoz-Gil ◽  
Przemysław Ryszard Grzybowski ◽  
Maciej Lewenstein
Keyword(s):  
Anomalous Diffusion ◽  
Coupling Strength ◽  
Rabi Frequency ◽  
Einstein Condensate ◽  
The Other ◽  
One Dimensional ◽  
Bose Einstein Condensate ◽  
Coherent Coupling ◽  
Two Component ◽  
Bose Einstein

We study the diffusive behavior of a Bose polaron immersed in a coherently coupled two-component Bose-Einstein Condensate (BEC). We assume a uniform, one-dimensional BEC. Polaron superdiffuses if it couples in the same manner to both components, i.e. either attractively or repulsively to both of them. This is the same behavior as that of an impurity immersed in a single BEC. Conversely, the polaron exhibits a transient nontrivial subdiffusive behavior if it couples attractively to one of the components and repulsively to the other. The anomalous diffusion exponent and the duration of the subdiffusive interval can be controlled with the Rabi frequency of the coherent coupling between the two components, and with the coupling strength of the impurity to the BEC.

scholarly journals The Demonstration Model of an Electromagnetic Accelerator Gun

2018 ◽  
Vol 10 (1) ◽  
pp. 77-89
Author(s):  
Andras Molnar
Keyword(s):  
Energy Release ◽  
The Other ◽  
Chemical Energy ◽  
The Internet ◽  
Muzzle Velocity ◽  
Other Hand ◽  
Experimental Tool ◽  
Muzzle Energy ◽  
Serious Injury ◽  
Electromagnetic Accelerator

Abstract These days a lot can be heard about special weapons which accelerate the projectile not based on the traditional, chemical energy release, but providing the muzzle velocity with the help of electromagnets. In English terminology, many descriptions can be read about these devices, referred to as “coilgun”. There are so many hobbyist and amateurs who make these devices [1,2] and publish their results on the internet [3,4]. The purpose of the project is dual. On one hand, features, advantages, disadvantages and the limits of the electromagnetically accelerated weapons can be found by building an experimental tool. On the other hand, it was intended to point out the fact that anybody can build such a tool using commercially available commercial components. Although the muzzle energy of the device presented in this paper is not more than 6.8J, but it can cause serious injury. The paper also points out that in a similar way, still not using special components, a weapon can be made with a larger (10-20J) muzzle energy.

scholarly journals Allosteric regulation in CRISPR/Cas1-Cas2 protospacer acquisition mediated by DNA in association with Cas2

2020 ◽  
Author(s):  
Chunhong Long ◽  
Liqiang Dai ◽  
Chao E ◽  
Lin-Tai Da ◽  
Jin Yu
Keyword(s):  
Active Site ◽  
Active Sites ◽  
High Efficiency ◽  
Allosteric Regulation ◽  
The Other ◽  
Complementary Sequence ◽  
Protospacer Adjacent Motif ◽  
Association Reaction ◽  
Dynamics Simulations ◽  
Recognition And Response

ABSTRACTCas1 and Cas2 are highly conserved proteins across CRISPR-Cas systems and play a significant role in protospacer acquisition. Here we study the protospacer (or ps) DNA binding, recognition, and response to cleavage on the protospacer-adjacent-motif complementary sequence or PAMc by Cas1-Cas2, implementing all-atom molecular dynamics simulations. First, we noticed that two active sites of Cas1&1’ bind asymmetrically to two identical PAMc in the simulation. For psDNA containing only one PAMc to be recognized, it is then found that the non-PAMc association site remains destabilized until after the bound PAMc being cleaved. Thus, correlation appears to exist between the two active sites, which can be allosterically mediated by psDNA and Cas2&2’ in bridging. To substantiate such findings, we further simulated Cas1-Cas2 in complex with synthesized psDNA sequences psL and psH, which have been measured with low and high efficiency in acquisition, respectively. Notably, such inter-site correlation becomes largely enhanced for Cas1-Cas2 in complex with psH, and remains low with psL. Hence, our studies demonstrate that PAMc recognition and cleavage in one active site of Cas1-Cas2 allosterically regulates non-PAMc association/reaction in the other site, and such allosteric regulation is mediated by non-catalytic Cas 2 and DNA protospacer in acquisition.

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