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natural fractals

Anna Marie Sokac
In this issue of Developmental Cell, Goudarzi et al. (2017) examine the membrane source that allows bleb-based cell migration in vivo. Their work reminds us of the fractal nature of cell surfaces and highlights how the unfolding of these convoluted surfaces contributes to physiologically relevant cell shape change in intact organisms.
December 4, 2017: Developmental Cell
Quentin Chevalier, Hind El Hadri, Patrice Petitjean, Martine Bouhnik-Le Coz, Stéphanie Reynaud, Bruno Grassl, Julien Gigault
Cigarette butts (CGB) are equivalent to plastic litter in terms of number of pieces released directly into the environment. Due to their small size and social use, CGB are commonly found in natural systems, and several questions have been raised concerning the contaminants that are released with CGB, including metals, organic species, and nanoparticles. The aim of the present study is to investigate the release of nanoscale particles from CGB by leaching with rainwater. After seven days of passive stirring of both smoked and unsmoked CGB in synthetic rainwater, the solutions were treated and analyzed by specific nano-analytical methods...
November 27, 2017: Chemosphere
Frédéric Dierick, Anne-Laure Nivard, Olivier White, Fabien Buisseret
Locomotion is a natural task that has been assessed for decades and used as a proxy to highlight impairments of various origins. So far, most studies adopted classical linear analyses of spatio-temporal gait parameters. Here, we use more advanced, yet not less practical, non-linear techniques to analyse gait time series of healthy subjects. We aimed at finding more sensitive indexes related to spatio-temporal gait parameters than those previously used, with the hope to better identify abnormal locomotion. We analysed large-scale stride interval time series and mean step width in 34 participants while altering walking direction (forward vs...
2017: PloS One
K Lopez-de-Ipina, U Martinez-de-Lizarduy, P M Calvo, Jiri Mekyska, B Beitia, N Barroso, A Estanga, M Tainta, M Ecay-Torres
Nowadays proper detection of cognitive impairment has become a challenge for the scientific community. Alzheimer's Disease (AD), the most common cause of dementia, has a high prevalence that is increasing at a fast pace towards epidemic level. In the not-so-distant future this fact could have a dramatic social and economic impact. In this scenario, an early and accurate diagnosis of AD could help to decrease its effects on patients, relatives and society. Over the last decades there have been useful advances not only in classic assessment techniques, but also in novel non-invasive screening methodologies...
November 20, 2017: Current Alzheimer Research
Di Wu, Tai Min, Jian Zhou, Chen Li, Guobin Ma, Gaotian Lu, Minggang Xia, Zhengbin Gu
In van der Waals epitaxial growth, the substrate plays a particularly important role in the crystal morphology. Here, we synthesized MoS2 by chemical vapour deposition on silicon carbide (SiC). The obtained MoS2 dendritic crystals show six-fold symmetry, which are different from the conventional triangular shapes on SiO2 substrate and from those with three-fold symmetry on SrTiO3 substrate. Interestingly, these MoS2 dendritic crystals on SiC exhibit an average fractal dimension 1.76, which is slightly larger than the classical Diffusion-limited-Aggregation fractal dimension 1...
November 9, 2017: Scientific Reports
Viraj P Modak, Andrew J Amaya, Barbara E Wyslouzil
Whether crystallization starts at the liquid-vapor interface or randomly throughout the bulk has been the subject of intense debate. In our earlier work, we investigated the freezing of supercooled nanodroplets of short chain (C8, C9) n-alkanes formed by homogeneous condensation in a supersonic nozzle. The rate at which the solid appeared suggested freezing starts at the droplet surface well before the rest of the droplet freezes. Experiments were, however, limited to a single condition for each compound and it was not clear whether freezing of n-alkanes always occurs in this two step manner...
November 6, 2017: Physical Chemistry Chemical Physics: PCCP
R Jain, R Pitchumani
Superhydrophobic surfaces have myriad industrial applications, yet their practical utilization has been limited by their poor mechanical durability and longevity. We present a low-cost, facile process to develop superhydrophobic copper-based coatings via an electrodeposition route, that addresses this limitation. Through electrodeposition, a stable, multiscale, cauliflower shaped fractal morphology was obtained and upon modification by stearic acid, the prepared coatings show extreme water repellency with contact angle of 162 ± 2° and roll-off angle of about 3°...
November 17, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Rosendo Pérez-Isidoro, A D Reyes-Figueroa, J C Ruiz-Suárez
We sought to understand why saline drops produce intriguing patterns when drying in the presence of zwitterionic liposomes. Specifically, we would like to comprehend why the nature of such patterns is hierarchically driven by the Hofmeister series. The liposome suspension is made of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) with alkali metal chlorides. A complexity analysis of the patterns gives a fractal dimension around 1.71, which means that the drying process resembles a DLA mechanism. A physicochemical study, including the determination of zeta potential, molecular dynamics simulations, microrheology, and calorimetry, supports the fact that electrostatic interactions among head groups of phospholipids with alkali cations are the driven forces behind the assembling of the observed structures...
September 12, 2017: Colloids and Surfaces. B, Biointerfaces
A M Samarakoon, M Takahashi, D Zhang, J Yang, N Katayama, R Sinclair, H D Zhou, S O Diallo, G Ehlers, D A Tennant, S Wakimoto, K Yamada, G-W Chern, T J Sato, S-H Lee
Glassiness is ubiquitous and diverse in characteristics in nature. Understanding their differences and classification remains a major scientific challenge. Here, we show that scaling of magnetic memories with time can be used to classify magnetic glassy materials into two distinct classes. The systems studied are high temperature superconductor-related materials, spin-orbit Mott insulators, frustrated magnets, and dilute magnetic alloys. Our bulk magnetization measurements reveal that most densely populated magnets exhibit similar memory behavior characterized by a relaxation exponent of [Formula: see text]...
September 21, 2017: Scientific Reports
Soibam Shyamchand Singh, Dineshchandra Haobijam, Md Zubbair Malik, Romana Ishrat, R K Brojen Singh
We study brain network data of three species, namely, C. elegans, cat and macaque monkey within the framework of network theory and Potts Hamiltonian model, and explore rich fractal nature in it, which could be an important signature of self-organization, and a simple rule to be obeyed in complex patterns of brain networks. Further, this fractal behaviors in topological parameters of brain networks at various network levels could be an indicator of systems level organization in complicated brain functionality...
September 18, 2017: Journal of Theoretical Biology
Misha Ross, Georgia J Mason
Exposure to certain natural stimuli improves people's moods, reduces stress, enhances stress resilience, and promotes mental and physical health. Laboratory studies and real estate prices also reveal that humans prefer environments containing a broad range of natural stimuli. Potential mediators of these outcomes include: 1) therapeutic effects of specific natural products; 2) positive affective responses to stimuli that signalled safety and resources to our evolutionary ancestors; 3) attraction to environments that satisfy innate needs to explore and understand; and 4) ease of sensory processing, due to the stimuli's "evolutionary familiarity" and/or their fractal, self-repeating properties...
September 12, 2017: Neuroscience and Biobehavioral Reviews
Clara Llorens-Quintana, Maryam Mousavi, Dorota Szczesna-Iskander, D Robert Iskander
PURPOSE: To evaluate the effect of two types of daily contact lenses (delefilcon A and omafilcon A) on the tear film and establish whether it is dependent on pre-corneal tear film characteristics using a new method to analyse high-speed videokeratoscopy recordings, as well as to determine the sensitivity of the method in differentiating between contact lens materials on eye. METHODS: High-speed videokeratoscopy recordings were analysed using a custom made automated algorithm based on a fractal dimension approach that provides a set of parameters directly related to tear film stability...
August 29, 2017: Contact Lens & Anterior Eye: the Journal of the British Contact Lens Association
Sergio Kogikoski, Soma Khanra, Wendel A Alves, Suchismita Guha
Enhancing Raman signatures of molecules by self-assembled metal nanoparticles, nanolithography patterning, or by designing plasmonic nanostructures is widely used for detection of low abundance biological systems. Self-assembled peptide nanostructures provide a natural template for tethering Au and Ag nanoparticles due to its fractal surface. Here, we show the use of L,L-diphenylalanine micro-nanostructures (FF-MNSs) for the organization of Ag and Au nanoparticles (Nps) and its potential as surface-enhanced Raman scattering (SERS)-active substrates...
August 28, 2017: Journal of Chemical Physics
Miki U Kobayashi, Yoshitaka Saiki
A chaotic motion can be considered an irregular transition process near unstable periodic orbits embedded densely in a chaotic set. Therefore, unstable periodic orbits have been used to characterize properties of chaos. Statistical quantities of chaos such as natural measures and fractal dimensions can be determined in terms of unstable periodic orbits. Unstable periodic orbits that can provide good approximations to averaged quantities of chaos or turbulence are also known to exist. However, it is not clear what type of unstable periodic orbits can capture them...
August 2017: Chaos
Shixiong Yi, Fangyin Dai, Cunyi Zhao, Yang Si
Enzyme-immobilized nanoparticles that are both catalysis effective and recyclable would have wide applications ranging from bioengineering and food industry to environmental fields; however, creating such materials has proven extremely challenging. Herein, we present a scalable methodology to create Candida rugosa lipase-immobilized magnetic nanoparticles (L-MNPs) by the combination of nonionic reverse micelle method and Fe3O4 nanoparticles. Our approach causes the naturally abundant and sustainable Candida rugose lipase to ordered-assemble into nanoparticles with high catalytic activity and durability...
August 29, 2017: Scientific Reports
Rui Zhang, Shimin Liu, Yang Wang
Coalbed methane (CBM) and shale gas become two most important unconventional natural gas resources in US. The fractal dimension, known as the degree of self-similarity or irregularity, is an important parameter to quantitatively characterize gas storage capacity and gas transport properties in pores of rock matrix. In this study, two coal and two shale samples were evaluated to estimate fractal dimensions using combined small angle X-ray scattering (SAXS), small angle neutron scattering (SANS) and low-pressure N2 adsorption techniques...
August 21, 2017: Scientific Reports
Hana Koorehdavoudi, Paul Bogdan, Guopeng Wei, Radu Marculescu, Jiang Zhuang, Rika Wright Carlsen, Metin Sitti
To add to the current state of knowledge about bacterial swimming dynamics, in this paper, we study the fractal swimming dynamics of populations of Serratia marcescens bacteria both in vitro and in silico, while accounting for realistic conditions like volume exclusion, chemical interactions, obstacles and distribution of chemoattractant in the environment. While previous research has shown that bacterial motion is non-ergodic, we demonstrate that, besides the non-ergodicity, the bacterial swimming dynamics is multi-fractal in nature...
July 2017: Proceedings. Mathematical, Physical, and Engineering Sciences
Małgorzata Franus, Grzegorz Jozefaciuk, Lidia Bandura, Krzysztof Lamorski, Mieczysław Hajnos, Wojciech Franus
An admixture of lightweight aggregate substrates (beidellitic clay containing 10 wt % of natural clinoptilolite or Na-P1 zeolite) with used motor oil (1 wt %-8 wt %) caused marked changes in the aggregates' microstructure, measured by a combination of mercury porosimetry (MIP), microtomography (MT), and scanning electron microscopy. Maximum porosity was produced at low (1%-2%) oil concentrations and it dropped at higher concentrations, opposite to the aggregates' bulk density. Average pore radii, measured by MIP, decreased with an increasing oil concentration, whereas larger (MT) pore sizes tended to increase...
October 18, 2016: Materials
Sergio Bianchi, Massimiliano Frezza
The last systemic financial crisis has reawakened the debate on the efficient nature of financial markets, traditionally described as semimartingales. The standard approaches to endow the general notion of efficiency of an empirical content turned out to be somewhat inconclusive and misleading. We propose a topological-based approach to quantify the informational efficiency of a financial time series. The idea is to measure the efficiency by means of the pointwise regularity of a (stochastic) function, given that the signature of a martingale is that its pointwise regularity equals 12...
July 2017: Chaos
Xiang Cai, Liguo Shen, Meijia Zhang, Jianrong Chen, Huachang Hong, Hongjun Lin
Quantitatively evaluating interaction energy between two randomly rough surfaces is the prerequisite to quantitatively understand and control membrane fouling in membrane bioreactors (MBRs). In this study, a new unified approach to construct rough topographies and to quantify interaction energy between a randomly rough particle and a randomly rough membrane was proposed. It was found that, natural rough topographies of both foulants and membrane could be well constructed by a modified two-variable Weierstrass-Mandelbrot (WM) function included in fractal theory...
November 2017: Bioresource Technology
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