Journal articles: 'Mechanochemical patterns'

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Liu, Aibo, and Changchun Liu. "ASYMPTOTIC DYNAMICS OF A NEW MECHANOCHEMICAL MODEL IN BIOLOGICAL PATTERNS." Mathematical Modelling and Analysis 22, no. 2 (March 18, 2017): 252–69. http://dx.doi.org/10.3846/13926292.2017.1292324.

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In this paper, we prove the existence of attractor for a new mechanochemical model with Neumann boundary conditions on a bounded domain of space dimension n ≤ 3. Based on the regularity estimates for the semigroups and the classical existence theorem of global attractors, we prove that the mechanochemical model possesses a global attractor and Hk attractor.

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Can, Musa Mutlu, Yeşim Akbaba, and Satoru Kaneko. "Synthesis of Iron Gallate (FeGa2O4) Nanoparticles by Mechanochemical Method." Coatings 12, no. 4 (March 22, 2022): 423. http://dx.doi.org/10.3390/coatings12040423.

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The study was focused on optimizing the procedure of synthesizing iron gallate (FeGa2O4) nanoparticles by mechanochemical techniques. Due to a lack of information in the literature about the sequence of synthesis procedures of FeGa2O4 structures, the study is based on the establishment of a recipe for FeGa2O4 synthesis using mechanochemical techniques. Rotation speed, grinding media, and milling durations were the optimized parameters. At the end of each step, the structure of the resulting samples was investigated using the X-ray diffraction (XRD) patterns of samples. At the end of the processes, the XRD patterns of the samples milled under an air atmosphere were coherent with the XRD pattern of the FeGa2O4 structure. XRD patterns were analyzed employing Rietveld refinements to determine lattice parameters under the assumption of an inverse spinel crystal formation. Furthermore, a fluctuation at band gap values in the range of 2.39 to 2.55 eV was realized and associated with the excess Fe atoms in the lattice, which settled as defects in the crystal structures.

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Recho, Pierre, Adrien Hallou, and Edouard Hannezo. "Theory of mechanochemical patterning in biphasic biological tissues." Proceedings of the National Academy of Sciences 116, no. 12 (February 28, 2019): 5344–49. http://dx.doi.org/10.1073/pnas.1813255116.

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The formation of self-organized patterns is key to the morphogenesis of multicellular organisms, although a comprehensive theory of biological pattern formation is still lacking. Here, we propose a minimal model combining tissue mechanics with morphogen turnover and transport to explore routes to patterning. Our active description couples morphogen reaction and diffusion, which impact cell differentiation and tissue mechanics, to a two-phase poroelastic rheology, where one tissue phase consists of a poroelastic cell network and the other one of a permeating extracellular fluid, which provides a feedback by actively transporting morphogens. While this model encompasses previous theories approximating tissues to inert monophasic media, such as Turing’s reaction–diffusion model, it overcomes some of their key limitations permitting pattern formation via any two-species biochemical kinetics due to mechanically induced cross-diffusion flows. Moreover, we describe a qualitatively different advection-driven Keller–Segel instability which allows for the formation of patterns with a single morphogen and whose fundamental mode pattern robustly scales with tissue size. We discuss the potential relevance of these findings for tissue morphogenesis.

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Ajmi, A., K. Karoui, K. Khirouni, and A. Ben Rhaiem. "Optical and dielectric properties of NaCoPO4 in the three phases α, β and γ." RSC Advances 9, no. 26 (2019): 14772–81. http://dx.doi.org/10.1039/c9ra01558b.

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In this work, we are interested in the synthesis of monophosphate α-NaCoPO₄, β-NaCoPO₄ and γ-NaCoPO₄ compounds by mechanochemical method and their characterization by X-ray powder diffraction patterns.

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Dewers, T., and Peter Ortoleva. "Self-organization of mineralization patterns in metamorphic rocks through mechanochemical coupling." Journal of Physical Chemistry 93, no. 7 (April 1989): 2842–48. http://dx.doi.org/10.1021/j100344a028.

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Liu, Changchun, and Xiaoli Zhang. "Optimal distributed control for a new mechanochemical model in biological patterns." Journal of Mathematical Analysis and Applications 478, no. 2 (October 2019): 825–63. http://dx.doi.org/10.1016/j.jmaa.2019.05.057.

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Staddon, Michael F., Edwin M. Munro, and Shiladitya Banerjee. "Pulsatile contractions and pattern formation in excitable actomyosin cortex." PLOS Computational Biology 18, no. 3 (March 30, 2022): e1009981. http://dx.doi.org/10.1371/journal.pcbi.1009981.

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The actin cortex is an active adaptive material, embedded with complex regulatory networks that can sense, generate, and transmit mechanical forces. The cortex exhibits a wide range of dynamic behaviours, from generating pulsatory contractions and travelling waves to forming organised structures. Despite the progress in characterising the biochemical and mechanical components of the actin cortex, the emergent dynamics of this mechanochemical system is poorly understood. Here we develop a reaction-diffusion model for the RhoA signalling network, the upstream regulator for actomyosin assembly and contractility, coupled to an active actomyosin gel, to investigate how the interplay between chemical signalling and mechanical forces regulates stresses and patterns in the cortex. We demonstrate that mechanochemical feedback in the cortex acts to destabilise homogeneous states and robustly generate pulsatile contractions. By tuning active stress in the system, we show that the cortex can generate propagating contraction pulses, form network structures, or exhibit topological turbulence.

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Wu, Hao, Cheng Chen, Dan Yu Jiang, Tao Feng, and Qiang Li. "Mechanochemical Synthesis and Characteristics of Pb(Mg_1/3Nb_2/3)O₃." Advanced Materials Research 177 (December 2010): 29–31. http://dx.doi.org/10.4028/www.scientific.net/amr.177.29.

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This paper presents a novel mechanochemical synthesis technique for making nano-structured Pb(Mg1/3Nb2/3)O3 (PMN) ferroelectric material without annealing treatment in a much shorter time and at much lower temperature than those reported in the literature, by using the starting precursors MgO, PbO, and Nb2O5. Specimens of various milling time (3-6h) are characterized from XRD patterns to track and analyze the synthesizing procedure of this mechanochemical processing route. The time used to make the desired PMN powders varies with different milling power. When the constituent oxides were mechanically activated at 1.8KW milling power for 6h, the perovskite phase PMN powder was obtained; while it was formed when milling at 3KW for only 3h. Typical SEM images of the as-received PMN powders show that the powders are aggregated of nano-particles of about 100nm in size.

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Noguchi, Hiroshi, and Naoki Tamemoto. "Nonequilibrium dynamics of a fluid vesicle: Turing patterns and traveling waves." Journal of Physics: Conference Series 2207, no. 1 (March 1, 2022): 012017. http://dx.doi.org/10.1088/1742-6596/2207/1/012017.

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Abstract In living cells, the shapes of biomembranes are dynamically regulated by proteins. We briefly review our recent studies on the membrane dynamics coupled with reaction-diffusion dynamics of curvature-inducing proteins. We simulated a vesicle in a fluid phase using a dynamically triangulated membrane model combined with a modified Brusselator model. The mechanochemical feedback of curvature-inducing proteins changes the condition of Turing patterns relative to those that occur on a non-deformable curved surface. Budding and multi-spindle shapes are also stabilized by Turing patterns. The speed of traveling waves increases or decreases with increasing local membrane curvature depending on the condition. Moreover, the reaction-diffusion waves can induce the self-oscillation of vesicle shapes.

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Baláž, Peter, Parviz Pourghahramani, Erika Dutková, Martin Fabián, Jaroslav Kováč, and Alexander Šatka. "PbS nanostructures synthesized via surfactant assisted mechanochemical route." Open Chemistry 7, no. 2 (June 1, 2009): 215–21. http://dx.doi.org/10.2478/s11532-009-0005-3.

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AbstractPbS nanocrystals using surfactant assisted mechanochemical route has been successfully prepared. The methods of XRD, SEM, surface area and particle size measurements were used for nanocrystals characterization. The XRD patterns confirmed the presence of galena PbS (JCPDS 5–592) whatever treatment conditions were applied. The strong observable peaks indicate the highly crystalline nature in formation of PbS nanostructures where preferential crystal growth in the (200) direction after chelating agent (EDTANa2•2H2O) addition has been observed. The mean volume weighted crystallite size 4.9 nm and 35 nm has been calculated from XRD data using Williamson-Hall method for PbS synthesized without and/or with chelating agent, respectively corresponding with surface weighted crystallites sizes of 2.9 and 18.8 nm. The sample prepared without surfactant yields the smaller crystallites and the higher microstrain compared with surfactant assisted synthesis. The obtained results illustrate a possibility to manipulate crystal morphology by combining effect of milling and surfactant application.

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Rueda-Contreras, Mara D., José R. Romero-Arias, José L. Aragón, and Rafael A. Barrio. "Curvature-driven spatial patterns in growing 3D domains: A mechanochemical model for phyllotaxis." PLOS ONE 13, no. 8 (August 16, 2018): e0201746. http://dx.doi.org/10.1371/journal.pone.0201746.

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Radszuweit, Markus, Harald Engel, and Markus Bär. "An Active Poroelastic Model for Mechanochemical Patterns in Protoplasmic Droplets of Physarum polycephalum." PLoS ONE 9, no. 6 (June 13, 2014): e99220. http://dx.doi.org/10.1371/journal.pone.0099220.

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Shokuhfar, Ali, Bahman Nasiri-Tabrizi, Omid Gashti, and Reza Ebrahimi-Kahrizsangi. "Effect of Polymeric Milling Media on the Mechanosynthesis and Structural Properties of Nanocrystalline Hydroxyapatite." Defect and Diffusion Forum 283-286 (March 2009): 98–105. http://dx.doi.org/10.4028/www.scientific.net/ddf.283-286.98.

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Mechanochemical process in polymeric vials has been carried out successfully to produce nanocrystalline hydroxyapatite (HAp) through two different reactions R1 and R2. Morphological properties and structural evaluation of obtained materials are studied by X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM). The obtained data show that the increase in milling time leads the increasing in lattice strain and decreasing in crystallite size. The average crystallite size of HAp is below 20 and 23 nm for R1 and R2 reactions, respectively. Based on XRD patterns and SEM/TEM micrographs, the possible formation mechanism of nanocrystalline hydroxyapatite by mechanochemical process in polymeric milling media is confirmed. Final results indicate that the nanocrystalline hydroxyapatite with low chemically stable contaminations and suitable morphology can be produced in Polyamide6 vials similar to stainless steel vials, therefore it seems that using polymeric vials could lead to a new way for the mass production of nanocrystalline hydroxyapatite with high performance, low contamination and cost and also suitable morphology.

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Kanno, Yoshinori. "Tetragonal-orthorhombic phase transformation and sintering behavior of KSbOSiO4 (isomorphous derivative of KTP)." Journal of Materials Research 9, no. 9 (September 1994): 2323–29. http://dx.doi.org/10.1557/jmr.1994.2323.

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Fine KSbOSiO4 (KSS) powders have been prepared by a sol-gel method starting from the system of TEOS, KSb(OH)6, H2O, C2H5OH, or mechanochemical mixing method with a stoichiometric mixture of amorphous silica and KSb(OH)6. The KSS crystallized sluggishly into a tetragonal symmetry in low temperature and transformed into an orthorhombic one in higher temperature, indicating the amorphous-like powder patterns in the intermediate step. This amorphization process could be related to some redistribution of the polysilicate network structures. The mechanochemical activation energy stored in the powder surface, as well as the coexisting matrix (KSbO3), retards the transformation. It was concluded that the KSS powders composed of high molecular weight siloxane polymers, which were formed by hydrolysis in the presence of a small amount of NH3 aqueous solution, showed higher sinterability. The sintering, where the calcining process was omitted, enabled the dense tetragonal-type ceramics stabilized at lower temperature, rather than higher temperature, to fabricate.

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Park, JinSeok, William R. Holmes, Sung Hoon Lee, Hong-Nam Kim, Deok-Ho Kim, Moon Kyu Kwak, Chiaochun Joanne Wang, Leah Edelstein-Keshet, and Andre Levchenko. "Mechanochemical feedback underlies coexistence of qualitatively distinct cell polarity patterns within diverse cell populations." Proceedings of the National Academy of Sciences 114, no. 28 (June 27, 2017): E5750—E5759. http://dx.doi.org/10.1073/pnas.1700054114.

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Cell polarization and directional cell migration can display random, persistent, and oscillatory dynamic patterns. However, it is not clear whether these polarity patterns can be explained by the same underlying regulatory mechanism. Here, we show that random, persistent, and oscillatory migration accompanied by polarization can simultaneously occur in populations of melanoma cells derived from tumors with different degrees of aggressiveness. We demonstrate that all of these patterns and the probabilities of their occurrence are quantitatively accounted for by a simple mechanism involving a spatially distributed, mechanochemical feedback coupling the dynamically changing extracellular matrix (ECM)–cell contacts to the activation of signaling downstream of the Rho-family small GTPases. This mechanism is supported by a predictive mathematical model and extensive experimental validation, and can explain previously reported results for diverse cell types. In melanoma, this mechanism also accounts for the effects of genetic and environmental perturbations, including mutations linked to invasive cell spread. The resulting mechanistic understanding of cell polarity quantitatively captures the relationship between population variability and phenotypic plasticity, with the potential to account for a wide variety of cell migration states in diverse pathological and physiological conditions.

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Moreo, P., E. A. Gaffney, J. M. García-Aznar, and M. Doblaré. "On the Modelling of Biological Patterns with Mechanochemical Models: Insights from Analysis and Computation." Bulletin of Mathematical Biology 72, no. 2 (November 14, 2009): 400–431. http://dx.doi.org/10.1007/s11538-009-9452-4.

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Beraldo da Silveira Balestrin, Lia, Douglas Del Duque, Douglas Soares da Silva, and Fernando Galembeck. "Triboelectricity in insulating polymers: evidence for a mechanochemical mechanism." Faraday Discuss. 170 (2014): 369–83. http://dx.doi.org/10.1039/c3fd00118k.

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Transfer of reaction products formed on the surfaces of two mutually rubbed dielectric solids makes an important if not dominating contribution to triboelectricity. New evidence in support of this statement is presented in this report, based on analytical electron microscopy coupled to electrostatic potential mapping techniques. Mechanical action on contacting surface asperities transforms them into hot-spots for free-radical formation, followed by electron transfer producing cationic and anionic polymer fragments, according to their electronegativity. Polymer ions accumulate creating domains with excess charge because they are formed at fracture surfaces of pulled-out asperities. Another factor for charge segregation is the low polymer mixing entropy, following Flory and Huggins. The formation of fractal charge patterns that was previously described is thus the result of polymer fragment fractal scatter on both contacting surfaces. The present results contribute to the explanation of the centuries-old difficulties for understanding the “triboelectric series” and triboelectricity in general, as well as the dissipative nature of friction, and they may lead to better control of friction and its consequences.

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Hongbo, Y., C. Meiling, W. Xiuhui, and G. Hong. "Synthesis Of Magnesium-Aluminum Layered Double Hydroxides By Mechanochemical Method And Its Solid State Reaction Kinetics." Archives of Metallurgy and Materials 60, no. 2 (June 1, 2015): 1455–57. http://dx.doi.org/10.1515/amm-2015-0152.

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Abstract A mechanochemical method is developed in preparing magnesium-aluminum-layered double hydroxides (MgAl-LDHs). This approach includes activation process and diffusion process. In order to verify the LDHs structure and study the reaction kinetics, X-ray diffraction (XRD) patterns, inductively coupled plasma(ICP) and physical adsorption instrument were characterized. The results show that activation time can change the surface of particles and affect the reaction grade. During the diffusion process, reaction time is the most important factor. The reaction energy (ΔQ) was calculated that is 6kJ/mol.

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Geyer, Veikko F., Jonathon Howard, and Pablo Sartori. "Ciliary beating patterns map onto a low-dimensional behavioural space." Nature Physics 18, no. 3 (January 10, 2022): 332–37. http://dx.doi.org/10.1038/s41567-021-01446-2.

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AbstractBiological systems are robust to perturbations at both the genetic and environmental levels, although these same perturbations can elicit variation in behaviour. The interplay between functional robustness and behavioural variability is exemplified at the organellar level by the beating of cilia and flagella. Cilia are motile despite wide genetic diversity between and within species, differences in intracellular concentrations of ATP and calcium, and considerable environment fluctuations in temperature and viscosity. At the same time, these perturbations result in a variety of spatio-temporal patterns that span a rich behavioural space. To investigate this behavioural space we analysed the dynamics of isolated cilia from the unicellular algae Chlamydomonas reinhardtii under many different environmental and genetic conditions. We found that, despite large changes in beat frequency and amplitude, the space of waveform shapes is low-dimensional in the sense that two features account for 80% of the observed variation. The geometry of this behavioural space accords with the predictions of a simple mechanochemical model in the low-viscosity regime. This allowed us to associate waveform shape variability with changes in only the curvature response coefficients of the dynein motors.

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Jia, Yu, Yuji Hotta, Kimiyasu Sato, Koji Watari, and Yoshinori Kanno. "Gelcasting of Mechanochemically Synthesized Hydroxyapatite." Key Engineering Materials 280-283 (February 2007): 1555–58. http://dx.doi.org/10.4028/www.scientific.net/kem.280-283.1555.

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Hydroxyapatite powders were prepared via mechanochemical synthesis method. The starting reagents for HAP powders were vibration ball milled for 2 h and then calcined at 800°C for 1 h. X-ray diffraction patterns and IR spectrum shown that pure crystalline apatite powder (HAP) was obtained. The as-synthesized powders were gelcasted and then sintered at 1200°C for 2 h. It was observed from SEM micrographs that the prepared green body has uniform microstructure. The bending strength of the dried green body was as high as 18 MPa that is enough to be machined into required form before sintering. The sintered ceramics has a density of 2.5 g/cm3 and a flexural strength of 72 MPa with a homogenous microstructure.

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Sorescu, Monica, L. Diamandescu, A. Sanns, D. Proch, J. Wood, and V. S. Teodorescu. "Synthesis and Characterization of Ceramic Nanoparticles System Based on Anatase-Doped Hematite." Research Letters in Materials Science 2007 (2007): 1–5. http://dx.doi.org/10.1155/2007/48962.

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ThexTiO2-(1−x)α-Fe2O3ceramic nanoparticles system has been obtained by mechanochemical activation forx= 0.1 and 0.5 and for ball milling times ranging from 2 to 12 hours. Structural and morphological characteristics of the anatase-doped hematite system were investigated by X-ray diffraction (XRD), Mössbauer spectroscopy, and transmission electron microscopy (TEM) combined with electron diffraction (ED). In the XRD patterns, we could evidence the dissolution of anatase in hematite, more pronounced forx= 0.1. The Rietveld structure of the XRD patterns yielded the dependence of the particle size and lattice constants on the amountxof Ti substitutions and as function of the ball milling time. Forx= 0.1, we observed line broadening of the Mössbauer resonances and corresponding fit with several subspectra. Forx= 0.5, it can be observed that the central doublet corresponding to superparamagnetic particles becomes more prominent. The ball milling route allowed us to reach nanometric particle dimensions, which would make the materials very promising for catalytic and gas sensing applications.

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Halim, Nadiah, Noor Izzati Nadzri, and Vannajan Sanghiran Lee. "Active Pharmaceutical Ingredients co-crystals via solvent-free reactions." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C1786. http://dx.doi.org/10.1107/s205327331408214x.

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Dual-drug co-crystals comprising of active pharmaceutical ingredients (APIs); uracil and 5-fluorouracil with urea have been obtained by mechanochemical reactions. The formation of these co-crystals is typically towards drug design which is to help enhancing the solubility, stability and bioactivity in pharmaceutical development without changing the chemical composition of the APIs. These organic molecules undergo molecular recognition process to obtain a range of two dimensional networks through persistent hydrogen-bonding patterns adopted by certain functional groups, which acts as template and rely on the robustness of such motifs to create new solid- state structures. Hence, here we report the characterization, structural studies, binding energy and also the CDOCKER interaction of the co-crystals.

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Morales, M. A., J. F. Rojas, J. Oliveros, and A. A. Hernández S. "A new mechanochemical model: Coupled Ginzburg–Landau and Swift–Hohenberg equations in biological patterns of marine animals." Journal of Theoretical Biology 368 (March 2015): 37–54. http://dx.doi.org/10.1016/j.jtbi.2014.12.005.

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RAMEZANALIZADEH, H., and S. HESHMATI-MANESH. "MECHANOCHEMICAL REDUCTION OF MoO3 POWDER BY Al AND Si TO SYNTHESIZE NANOCRYSTALLINE MoSi2." International Journal of Modern Physics: Conference Series 05 (January 2012): 119–26. http://dx.doi.org/10.1142/s2010194512001924.

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In this study, mechanical alloying was used to produce MoSi 2 powder directly from molybdenum trioxide. Mixture of MoO 3, Si and Al powders were exposed to high mechanical activation in a planetary ball mill. The ball to powder mass ratio was constant at 33:1 and the rotation speed (cup speed) was 290 rpm during the milling operations. Phase compositions and structural evolutions during milling were investigated by X-ray diffraction analysis. The morphology of the mechanically alloyed powders was evaluated with scanning electron microscope (SEM). From XRD results, it was observed that within 3 hours of milling, MoO 3 was completely reduced and a MoSi 2- Al 2 O 3 composite powder was produced. Further milling resulted in transformation of β- MoSi 2 phase to α- MoSi 2. Mean crystallite sizes in product phases in the sample milled for 30 hours calculated by Scherer method using XRD patterns were found to be less than 100 nm.

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Patel, Kirtan D., Alison YY Tang, Ashik DJ Zala, Rakesh Patel, Kishan R. Parmar, and Saroj Das. "Referral patterns for catheter-directed thrombolysis for iliofemoral deep venous thrombosis." Phlebology: The Journal of Venous Disease 36, no. 7 (January 11, 2021): 562–69. http://dx.doi.org/10.1177/0268355520977281.

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Objectives Post thrombotic syndrome (PTS) is a serious complication of deep venous thromboses (DVTs). PTS occurs more frequently and severely following iliofemoral DVT compared to distal DVTs. Catheter directed thrombolysis (CDT) of iliofemoral DVTs may reduce PTS incidence and severity. We aimed to determine the rate of iliofemoral DVT within our institution, their subsequent management, and compliance with NICE guidelines. Methods Retrospective review of all DVTs diagnosed over a 3-year period was conducted. Cases of iliofemoral DVT were identified using ICD-10 codes from patient notes, and radiology reports of Duplex scans. Further details were retrieved, such as patient demographics and referrals to vascular services. NICE guidance was applied to determine if patients would have been suitable for CDT. A survey was sent to clinicians within medicine to identify awareness of CDT and local guidelines for iliofemoral DVT management. Results 225 patients with lower limb DVTs were identified. Of these, 96 were radiographically confirmed as iliofemoral DVTs. The median age was 77. 67.7% of iliofemoral DVTs affected the left leg. Right leg DVTs made up 30.2% and 2.1% were bilateral DVTs. Of the 96 iliofemoral DVTs, 21 were deemed eligible for CDT. Only 3 patients (14.3%) were referred to vascular services, and 3 received thrombolysis. From our survey, 95.5% of respondents suggested anticoagulation alone as management for iliofemoral DVT. Only one respondent recommended referral to vascular services. There was a knowledge deficiency regarding venous anatomy, including superficial versus deep veins. Conclusions CDT and other mechanochemical procedures have been shown to improve outcomes of patients post-iliofemoral DVT, however a lack of awareness regarding CDT as a management option results in under-referral to vascular services. We suggest closer relations between vascular services and their “tributary” DVT clinics, development of guidelines and robust care pathways in the management of iliofemoral DVT.

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Reems, Jo Anna, Wenjing Wang, Ken Tsubata, Birgitta Sundell, and Diana M. Gilligan. "Dynamin 3 Is Differentially Expressed during Human Megakaryocyte Development." Blood 108, no. 11 (November 16, 2006): 4162. http://dx.doi.org/10.1182/blood.v108.11.4162.4162.

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Abstract We found that expression of dynamin 3 (DNM3) is increased significantly when human CD34+/CD38lo cells are induced to develop along the megakaryocyte (MK) lineage. DNM3 is a member of a family of mechanochemical enzymes which participate in membrane dynamics. Of the 3 family members (DNM1, DNM2 and DNM3), cDNA microarray analysis showed that only DNM3 significantly increased by 9.5±1.8-fold (mean±SEM; p≤0.001). mRNAs for DNM1 and DNM2 were detectable, but their expression levels remained essentially unchanged during MK differentiation. Consistent with our microarray data, real time quantitative RT-PCR confirmed that DNM3 expression levels increased by as much as 20.0±7.3 fold during megakaryocytopoiesis. Western Blot analysis showed that protein expression patterns for each of the 3 dynamins differ in MKs/platelets. DNM3 protein expression levels are greater in MKs than in platelets. DNM1 was not detectable in MKs, but was present in platelets. Although DNM2 protein was detectable in both MKs and platelets, the relative mobility for DNM2 was slightly lower in platelets than MKs. Indirect immunofluorescent microscopy showed that DNM3 was predominantly in the cytoplasm with localization to sites that appear to be regions of pro-platelet formation. The cDNA encoding DNM3 was amplified from culture derived human MKs, cloned and sequenced. Sequence analysis revealed that the cloned product matched a DNM3 transcriptional splice variant in the Ensemble Human GeneView database (i.e. ENST00000367731). Together these results are the first evidence indicating that members of the dynamin family of mechanochemical proteins are present in human MKs and suggest that they may play an important role in MK membrane dynamics.

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Han, Joo Hyeong, and Won Bin Im. "Mechanochemical Synthesis As a Green Route: Cs₃Cu₂X₅ (X = Cl, Br, I) and CsCu₂I₃ and Their Reversible Phase Transitions." ECS Meeting Abstracts MA2022-02, no. 51 (October 9, 2022): 1986. http://dx.doi.org/10.1149/ma2022-02511986mtgabs.

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Cesium copper halides (CCHs) show promise for optoelectronic applications, and their syntheses usually involve high-temperatures and hazard solvents. Herein, the synthesis of highly luminescent and phase-pure Cs3Cu2X5 (X = Cl, Br, and I) and CsCu2I3 via a solvent-free mechanochemical approach through manual grinding is demonstrated. This cost-effective approach can produce CCHs on a scale of tens to hundreds of grams. Rietveld refinement analysis of the X-ray diffraction patterns of the as-synthesized CCHs reveals their structural details. Notably, the emission characteristics of green-emitting, chloride-based CCHs remain stable even at elevated temperatures──maintaining 80% of initial PL efficiency at 150 °C. Lastly, a postsynthetic reversible transformation between zero- and one-dimensional CCH materials is demonstrated, indicating the labile nature of their crystal structure. The proposed study suggests that mechanochemistry can be an alternative and promising synthetic tool for fabricating high-quality lead-free metal halides.

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Helmlinger, G., B. C. Berk, and R. M. Nerem. "Calcium responses of endothelial cell monolayers subjected to pulsatile and steady laminar flow differ." American Journal of Physiology-Cell Physiology 269, no. 2 (August 1, 1995): C367—C375. http://dx.doi.org/10.1152/ajpcell.1995.269.2.c367.

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The vascular endothelium is the primary transducer of hemodynamically imposed mechanochemical events. In this study, we measured the intracellular free calcium concentration ([Ca2+]i) using the fluorescent probe fura 2 and ratiometric digital imaging in cultured bovine aortic endothelial cells (BAEC) subjected to various laminar flow patterns. These were steady shear stress (0.2-70 dyn/cm2) and three types of sinusoidal pulsatile shear stress (nonreversing: 40 +/- 20 dyn/cm2; reversing: 20 +/- 40 dyn/cm2; and purely oscillatory: 0 +/- 20 dyn/cm2; flow frequencies: 0.4, 1.0, and 2.0 Hz) in a serum-containing medium. The most dramatic finding was failure of a purely oscillatory flow to increase [Ca2+]i in BAEC monolayers. In contrast, steady flow, as well as nonreversing and reversing pulsatile flows, increased [Ca2+]i. The dynamics of the response were dependent on the flow pattern. Both internal Ca2+ release and extracellular Ca2+ entry were involved in these [Ca2+]i increases. Also, switching from either a steady nonreversing pulsatile or reversing pulsatile flow back to a static condition resulted in a [Ca2+]i increase. However, switching from an oscillatory flow to a static condition did not induce any changes in average [Ca2+]i. This study shows that endothelial cells are able to sense different flow environments in terms of [Ca2+]i signaling and is relevant to further studies of the influence of hemodynamic forces on vascular pathophysiology.

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Julien, Jean-Daniel, and Karen Alim. "Oscillatory fluid flow drives scaling of contraction wave with system size." Proceedings of the National Academy of Sciences 115, no. 42 (October 3, 2018): 10612–17. http://dx.doi.org/10.1073/pnas.1805981115.

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Flows over remarkably long distances are crucial to the functioning of many organisms, across all kingdoms of life. Coordinated flows are fundamental to power deformations, required for migration or development, or to spread resources and signals. A ubiquitous mechanism to generate flows, particularly prominent in animals and amoebas, is actomyosin cortex-driven mechanical deformations that pump the fluid enclosed by the cortex. However, it is unclear how cortex dynamics can self-organize to give rise to coordinated flows across the largely varying scales of biological systems. Here, we develop a mechanochemical model of actomyosin cortex mechanics coupled to a contraction-triggering, soluble chemical. The chemical itself is advected with the flows generated by the cortex-driven deformations of the tubular-shaped cell. The theoretical model predicts a dynamic instability giving rise to stable patterns of cortex contraction waves and oscillatory flows. Surprisingly, simulated patterns extend beyond the intrinsic length scale of the dynamic instability—scaling with system size instead. Patterns appear randomly but can be robustly generated in a growing system or by flow-generating boundary conditions. We identify oscillatory flows as the key for the scaling of contraction waves with system size. Our work shows the importance of active flows in biophysical models of patterning, not only as a regulating input or an emergent output, but also as a full part of a self-organized machinery. Contractions and fluid flows are observed in all kinds of organisms, so this concept is likely to be relevant for a broad class of systems.

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Ramezanalizadeh, H., and Saeed Heshmati-Manesh. "Mechanochemical Reduction of MoO₃ Powder by Silicone to Synthesize Nanocrystalline MoSi₂." Advanced Materials Research 264-265 (June 2011): 1364–69. http://dx.doi.org/10.4028/www.scientific.net/amr.264-265.1364.

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Molybdenum disiliside is known as a ceramic material with attractive properties for high temperature structural applications. In this study, mechanical alloying was used to produce MoSi2 powder directly from molybdenum oxide. Mixture of MoO3 and Si powders with commercial purity were exposed to high mechanical activation in a planetary ball mill. The ball to powder mass ratio was selected to be constant at 33:1 and the rotation speed (cup speed) was 600 rpm during the milling operations. Crystallite sizes and structural evolutions during milling were investigated by Xray diffraction analysis. The morphology of the mechanically alloyed powders was evaluated with scanning electron microscope (SEM). From XRD results, it was observed that within 6 hours of milling MoO3 was reduced and fully converted to MoO2. After 17 hours of milling MoO2 also began to reduce and peaks of MoSi2 (both and phases) and Mo were detected. Further milling resulted in a gradual decrease in MoO2 peak intensities because of its continuous reduction. Peaks of MoO2 were also broadened due to refinement of MoO2 crystallite sizes. Scherrer and Williamson-Hall methods using XRD patterns were employed to calculate the mean crystallite size. Calculations indicated that in the sample ball milled for 50 hours, MoSi2 crystallite sizes were less than 100 nm.

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Molla, Md, Mai Furukawa, Ikki Tateishi, Hideyuki Katsumata, and Satoshi Kaneco. "Studies of Effects of Calcination Temperature on the Crystallinity and Optical Properties of Ag-Doped ZnO Nanocomposites." Journal of Composites Science 3, no. 1 (February 14, 2019): 18. http://dx.doi.org/10.3390/jcs3010018.

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Ag-doped ZnO nanocomposites are successfully synthesized at different calcination temperatures and times through a simple, effective, high-yield and low-cost mechanochemical combustion technique. Effects of calcination temperature on the crystallinity and optical properties of Ag/ZnO nanocomposites have been studied by X-ray diffraction (XRD), UV−visible diffuse reflectance spectroscopy (UV-DRS), photoluminescence spectroscopy (PL) and X-ray photoelectron spectroscopy (XPS). The XRD patterns of the synthesized Ag/ZnO exhibit a well-crystalline wurtzite ZnO crystal structure. The grain size of Ag/ZnO nanocomposites is found to be 19 and 46 nm at calcination temperatures of 400 °C and 700 °C, respectively. The maximum absorption in the UV region is obtained for Ag/ZnO nanocomposites synthesized at a calcination temperature of 500 °C for 3 h. The peak position of blue emissions is almost the same for the nanocomposites obtained at 300–700 °C calcination temperatures. The usual band edge emission in the UV is not obtained at 330 nm excitation. Band edge and blue band emissions are observed for the use of low excitation energy at 335–345 nm.

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Zhang, Shuwen, and Youdong Mao. "AAA+ ATPases in Protein Degradation: Structures, Functions and Mechanisms." Biomolecules 10, no. 4 (April 18, 2020): 629. http://dx.doi.org/10.3390/biom10040629.

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Adenosine triphosphatases (ATPases) associated with a variety of cellular activities (AAA+), the hexameric ring-shaped motor complexes located in all ATP-driven proteolytic machines, are involved in many cellular processes. Powered by cycles of ATP binding and hydrolysis, conformational changes in AAA+ ATPases can generate mechanical work that unfolds a substrate protein inside the central axial channel of ATPase ring for degradation. Three-dimensional visualizations of several AAA+ ATPase complexes in the act of substrate processing for protein degradation have been resolved at the atomic level thanks to recent technical advances in cryogenic electron microscopy (cryo-EM). Here, we summarize the resulting advances in structural and biochemical studies of AAA+ proteases in the process of proteolysis reactions, with an emphasis on cryo-EM structural analyses of the 26S proteasome, Cdc48/p97 and FtsH-like mitochondrial proteases. These studies reveal three highly conserved patterns in the structure–function relationship of AAA+ ATPase hexamers that were observed in the human 26S proteasome, thus suggesting common dynamic models of mechanochemical coupling during force generation and substrate translocation.

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SADEGHI-NIARAKI, S., S. A. SEYYED EBRAHIM, and SH RAYGAN. "THE EFFECT OF HIGH ENERGY MILLING ON THE SR-HEXAFERRITE NANOCRYSTALLINE POWDER SYNTHESIZED BY A SOL-GEL AUTOCOMBUSTION METHOD." International Journal of Modern Physics: Conference Series 05 (January 2012): 765–70. http://dx.doi.org/10.1142/s2010194512002735.

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In this research SrFe 12 O 19 nanocrystalline synthesized by sol-gel auto-combustion method and subsequent annealing at 1000°C for 1h subjected to mechanochemical treatment in a high-energy ball mill and then re-annealing. A planetary ball mill (Fritsch Pulveristte 6) was used to mill the strontium hexaferrite powder at 300 rpm in air for 10, 20 and 40 hours. The process was studied by X-ray diffraction technique and scanning electron microscopy. The X-ray study showed that SrFe 12 O 19 phase was decomposed by milling. Strontium hexaferrite and α- Fe 2 O 3 were obtained with 10 hours milling. There were α- Fe 2 O 3 and strontium hexaferrite in XRD patterns of 20 hours milled sample. With increasing of the milling time to 40 hours, strontium hexaferrite was decomposed completely. The annealing of the 20 and 40 h milled powders at 900°C for 1h led to the formation of single phase strontium hexaferrite with smaller crystallite size compare to that of the hexaferrite powder before milling and subsequent annealing.

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Kul’pina, Yuliya N., Valery Yu Prokof’ev, Natalia E. Gordina, Olga E. Khmylova, Nina V. Petukhova, and Sevil I. Gazakhova. "USE OF IR SPECTROSCOPY FOR STUDY OF STRUCTURE OF LOW-MODULUS ZEOLITES." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 60, no. 5 (June 23, 2017): 44. http://dx.doi.org/10.6060/tcct.2017605.5405.

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A brief description of the low-modulus zeolites structure is given. Constructions of "building" units were discussed. Namely, the structures of TO4 tetrahedron, a simple four-membered ring (S4R), a double four-membered ring (D4R), a simple six-membered ring (S6R), a double six-membered ring (D6R), α-cell and β-cell were described in details. IR spectroscopy and X-ray diffraction were used to study the structure of zeolites. The types of interatomic bonds vibrations (stretching and deformation) were represented. The reasons of the absorption bands appearance in the IR spectra were described. The literature data for IR spectroscopy studies of zeolites structure were summarized. The ranges of localization of absorption bands on IR spectra for aluminosilicate frameworks as well as for OH groups and molecular water were identified. The absorption bands which correspond to the stretching and deformation vibrations of TO4, S4R, D4R, S6R and D6R were revealed. The examples of X-ray patterns and infrared spectra for the LTA and SOD samples were given. These samples were prepared from mixtures of metakaolin and sodium hydroxide with an atomic ratio Si: Al equals to 1: 1 and 1: 1⅓ using mechanochemical activation or ultrasonic treatment and calcined at various temperatures. It was shown that in the IR spectrum of SOD, absorption bands of TO4 and S4R were distinctly identified. The effect of mechanochemical and ultrasonic treatment of raw ingredients on the intensity of absorption bands was established. Also, the change in the IR spectrum of the LTA zeolite after calcination was demonstrated. It was found that with increasing calcination temperature, the intensity of the absorption bands of S4R, D4R decreases, which indicates the destruction of the zeolite framework.For citation:Kul’pina Yu.N., Prokof’ev V.Yu., Gordina N.E., Khmylova O.E., Petukhova N.V., Gazakhova S.I. Use of ir spectroscopy for study of structure of low-modulus zeolites. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 5. P. 44-50.

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Alonso, Sergio, Ulrike Strachauer, Markus Radszuweit, Markus Bär, and Marcus J. B. Hauser. "Oscillations and uniaxial mechanochemical waves in a model of an active poroelastic medium: Application to deformation patterns in protoplasmic droplets of Physarum polycephalum." Physica D: Nonlinear Phenomena 318-319 (April 2016): 58–69. http://dx.doi.org/10.1016/j.physd.2015.09.017.

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Xing, Haoran, and Varoujan Yaylayan. "Mechanochemical generation of Schiff bases and Amadori products and utilization of diagnostic MS/MS fragmentation patterns in negative ionization mode for their analysis." Carbohydrate Research 495 (September 2020): 108091. http://dx.doi.org/10.1016/j.carres.2020.108091.

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Liman, James, Carlos Bueno, Yossi Eliaz, Nicholas P. Schafer, M. Neal Waxham, Peter G. Wolynes, Herbert Levine, and Margaret S. Cheung. "The role of the Arp2/3 complex in shaping the dynamics and structures of branched actomyosin networks." Proceedings of the National Academy of Sciences 117, no. 20 (April 30, 2020): 10825–31. http://dx.doi.org/10.1073/pnas.1922494117.

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Actomyosin networks give cells the ability to move and divide. These networks contract and expand while being driven by active energy-consuming processes such as motor protein walking and actin polymerization. Actin dynamics is also regulated by actin-binding proteins, such as the actin-related protein 2/3 (Arp2/3) complex. This complex generates branched filaments, thereby changing the overall organization of the network. In this work, the spatiotemporal patterns of dynamical actin assembly accompanying the branching-induced reorganization caused by Arp2/3 were studied using a computational model (mechanochemical dynamics of active networks [MEDYAN]); this model simulates actomyosin network dynamics as a result of chemical reactions whose rates are modulated by rapid mechanical equilibration. We show that branched actomyosin networks relax significantly more slowly than do unbranched networks. Also, branched networks undergo rare convulsive movements, “avalanches,” that release strain in the network. These avalanches are associated with the more heterogeneous distribution of mechanically linked filaments displayed by branched networks. These far-from-equilibrium events arising from the marginal stability of growing actomyosin networks provide a possible mechanism of the “cytoquakes” recently seen in experiments.

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Balema, Viktor P., Jerzy W. Wiench, Marek Pruski, and Vitalij K. Pecharsky. "Solvent-free mechanochemical synthesis of phosphonium saltsElectronic supplementary information (ESI) available: X-ray diffraction patterns of 1. See http://www.rsc.org/suppdata/cc/b1/b111515d/." Chemical Communications, no. 7 (March 6, 2002): 724–25. http://dx.doi.org/10.1039/b111515d.

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39

Fry, Donald L. "Arterial intimal-medial permeability and coevolving structural responses to defined shear-stress exposures." American Journal of Physiology-Heart and Circulatory Physiology 283, no. 6 (December 1, 2002): H2341—H2355. http://dx.doi.org/10.1152/ajpheart.00219.2001.

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The purpose of this research was to examine the evolution of arterial shear stress-induced intimal albumin permeability and coevolving structural responses in swine arteries. Uniform laminar shear-stress responses were compared with those of a simulated “flow separation” stress field. These fields were created using specially designed flow-configuring devices in an experimentally controlled, metabolically supported, ex vivo thoracoabdominal aorta preparation. The Evans blue dye-albumin complex (EBD-alb) permeability patterns that evolved were measured by a reflectometric method. The corresponding tissue structural responses were evaluated by histological, immunostaining, and ultrastructural microscopic techniques. It was shown that when a previously in vivo-adapted artery is challenged by a new mechanochemical environment, it undergoes a sequence of adaptive processes over the ensuing 95 h. Intimal regions of laminar shear-stress exposure (∼16 dyn/cm2) responded initially (23 h) with an increase in permeability. With continued stress exposure, intimal-medial structural changes ensued that restored the artery to a physiologically normal permeability. Over this same period, adjacent endothelial regions exposed to simulated flow separation stress fields (∼0.03–0.27 dyn/cm2) developed early and progressively increasing permeability. This was associated with formation of local intimal edema, loss of intimal matrix material, and development of distinctively raised, gelatinous-appearing intimal lesions having a potentially preatheromatous architecture.

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Okuda, Satoru, Yasuhiro Inoue, Tadashi Watanabe, and Taiji Adachi. "Coupling intercellular molecular signalling with multicellular deformation for simulating three-dimensional tissue morphogenesis." Interface Focus 5, no. 2 (April 6, 2015): 20140095. http://dx.doi.org/10.1098/rsfs.2014.0095.

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During morphogenesis, three-dimensional (3D) multicellular structures emerge from biochemical and mechanical interplays among cells. In particular, by organizing their gradient within tissues, the diffusible signalling molecules play an essential role in producing the spatio-temporal patterns of cell status such as the differentiation states. Notably, this biochemical patterning can be dynamically coupled with multicellular deformations by signal-dependent cell activities such as contraction, adhesion, migration, proliferation and apoptosis. However, the mechanism by which these cellular activities mediate the interactions between multicellular deformations and patterning is still unknown. Herein, we propose a novel framework of a 3D vertex model to express molecular signalling among the mechanically deforming cells. By specifying a density of signalling molecules for each cell, we express their transport between neighbouring cells. By simulating signal-dependent epithelial growth, we found various types of tissue morphogenesis such as arrest, expansion, invagination and evagination. In the expansion phase, growth molecules were widely diffused with increasing tissue volume, which diluted the growth molecules in order to support the autonomous suppression of tissue growth. These results indicate that the proposed model successfully expresses 3D multicellular deformations dynamically coupled with biochemical patterning. We expect our proposed model to be a useful tool for predicting new phenomena emerging from mechanochemical coupling in multicellular morphogenesis.

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Zaharieva, Joana, Maria Milanova, and Dimitar Todorovsky. "Mechanochemical synthesis of thenoyltrifluoroacetone-1,10-phenanthroline europium complex." Open Chemistry 10, no. 6 (December 1, 2012): 1907–12. http://dx.doi.org/10.2478/s11532-012-0115-1.

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AbstractThe paper considers the possibilities for mechanochemical synthesis of rare earth complexes. The complex Eu(TTA)3·phen (HTTA — 2-thenoyltrifluoroacetone, phen — 1,10-phenanthroline) is synthesized by mechanical treatment of a mixture of EuCl3.6H2O, HTTA, phen and NaOH in planetary ball mill Pulverisette 7 for 30 min at 800 min−1. The non reacted starting reagents and reaction side products are separated by treating activated mixture with water-ethanol solution following a procedure proposed in the literature. The elemental composition, X-ray diffraction pattern, IR spectra, optical properties (excitation and emission spectra, luminescence lifetime) and morphology of the mechanochemically synthesized complex are compared with those of the complex prepared from solution by the conventional method. The results confirm close similarity in the molecular structure and identity of the elemental composition, X-ray diffractograms and fluorescence properties of the compounds prepared by both methods.

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42

Winatapura, Didin Sahidin, Ade Mulyawan, Ari Adi Wisnu, and Yunasfi. "Synthesis, Structure, Magnetic and Absorption Properties of Nd Doped Y₃Fe₅O₁₂ Garnets Prepared by Mechanochemical Method." Key Engineering Materials 855 (July 2020): 52–57. http://dx.doi.org/10.4028/www.scientific.net/kem.855.52.

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Neodymium substituted yttrium iron garnet (YIG) nanoparticles with compositional variation of NdxY3−xFe5O12 where x = 0.0, 0.2, 0.5 and 0.8 was prepared by mechanochemicals method using high energy milling (HEM). The characterization was done using X-rays diffractometer (XRD), scanning electron microscope (SEM), vibrating sample magnetometer (VSM) and vector network analyzer (VNA). It was found that the mechanical milling followed by sintering promotes the complete structural formation of the yttrium iron garnet (YIG) structure. The XRD patterns confirm the complete introduction of Nd3+ ion into the YIG with an addition of Nd doping concentration. nanocrystalline particles with high purity and sizes ranging from 0.12μm to 0.16μm were obtained. The magnetization value, Ms from all Nd-doped samples were obtained in the range between 34 to 37emu.g-1. The magnetic coercivity (Hc) was achieved of 0.012kOe (12Oe) for the non-doped sample (YNd-0) and then increase with the addition of neodymium concentration. The increase in Hc for all the sample series can be attributed to an enhancement of the magnetocrystalline anisotropy with anisotropic Fe2+. The variation of the reflection loss (RL) versus frequency was observed in Nd doped YIG, Y1-xNdxFe5O12 with x = 0.0 – 0.8 in the frequency range of 7 –12 GHz. The optimum reflection loss (RL) was found to be 8.66(-dB) at 9.5GHz in Y2.2Nd0.8Fe5O12 (YNd-08) for x = 0.8.

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Asim, Muhammad, Akbar Hussain, Safia Khan, Javeria Arshad, Tehmeena Maryum Butt, Amina Hana, Mehwish Munawar, et al. "Sol-Gel Synthesized High Entropy Metal Oxides as High-Performance Catalysts for Electrochemical Water Oxidation." Molecules 27, no. 18 (September 13, 2022): 5951. http://dx.doi.org/10.3390/molecules27185951.

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Hexanary high-entropy oxides (HEOs) were synthesized through the mechanochemical sol-gel method for electrocatalytic water oxidation reaction (WOR). As-synthesized catalysts were subjected to characterization, including X-ray diffraction (XRD), Fourier transforms infrared (FTIR) analysis, and scanning electron microscopy (SEM). All the oxide systems exhibited sharp diffraction peaks in XRD patterns indicating the defined crystal structure. Strong absorption between 400–700 cm−1 in FTIR indicated the formation of metal-oxide bonds in all HEO systems. WOR was investigated via cyclic voltammetry using HEOs as electrode platforms, 1M KOH as the basic medium, and 1M methanol (CH3OH) as the facilitator. Voltammetric profiles for both equiatomic (EHEOs) and non-equiatomic (NEHEOs) were investigated, and NEHEOs exhibited the maximum current output for WOR. Moreover, methanol addition improved the current profiles, thus leading to the electrode utility in direct methanol fuel cells as a sequential increase in methanol concentration from 1M to 2M enhanced the OER current density from 61.4 to 94.3 mA cm−2 using NEHEO. The NEHEOs comprising a greater percentage of Al, ([Al0.35(Mg, Fe, Cu, Ni, Co)0.65]3O4) displayed high WOR catalytic performance with the maximum diffusion coefficient, D° (10.90 cm2 s−1) and heterogeneous rate constant, k° (7.98 cm s−1) values. These primary findings from the EC processes for WOR provide the foundation for their applications in high-energy devices. Conclusively, HEOs are proven as novel and efficient catalytic platforms for electrochemical water oxidation.

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Rivera, Augusto, Jicli José Rojas, John Sadat-Bernal, Jaime Ríos-Motta, and Michael Bolte. "Mechanochemical synthesis and X-ray structural characterization of three 3-nitrophenol cocrystals with three aminal cage azaadamantanes: the role of the stereoelectronic effect on intermolecular hydrogen-bonding patterns." Acta Crystallographica Section C Structural Chemistry 75, no. 12 (November 22, 2019): 1635–43. http://dx.doi.org/10.1107/s205322961901516x.

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The structures of the cocrystalline adducts of 3-nitrophenol (3-NP) with 1,3,5,7-tetraazatricyclo[3.3.1.13,7]decane [HMTA, (1)] as the 2:1:1 hydrate, 2C6H5NO3·C6H12N4·H2O, (1a), with 1,3,6,8-tetraazatricyclo[4.3.1.13,8]undecane [TATU (2)] as the 2:1 cocrystal, 2C6H5NO3·C7H14N4, (2a), and with 1,3,6,8-tetraazatricyclo[4.4.1.13,8]dodecane [TATD, (3)] as the 2:1 cocrystal, 2C6H5NO3·C8H16N4, (3a), are reported. In the binary crystals (2a) and (3a), the 3-nitrophenol molecules are linked via O—H...N hydrogen bonds into aminal cage azaadamantanes. In (1a), the structure is stabilized by O—H...N and O—H...O hydrogen bonds, and generates ternary cocrystals. There are C—H...O hydrogen bonds present in all three cocrystals, and in (1a), there are also C—H...O and C—H...π interactions present. The presence of an ethylene bridge in the structures of (2) and (3) defines the formation of a hydrogen-bonded motif in the supramolecular architectures of (2a) and (3a). The differences in the C—N bond lengths of the aminal cage structures, as a result of hyperconjugative interactions and electron delocalization, were analysed. These three cocrystals were obtained by the solvent-free assisted grinding method. Crystals suitable for single-crystal X-ray diffraction were grown by slow evaporation from a mixture of hexanes.

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Houliston, E. "Microtubule translocation and polymerisation during cortical rotation in Xenopus eggs." Development 120, no. 5 (May 1, 1994): 1213–20. http://dx.doi.org/10.1242/dev.120.5.1213.

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The development of dorsal axial structures in frogs depends on a process of cortical rotation in which the cortex of the fertilised egg becomes displaced with respect to the cytoplasm. An array of aligned microtubules that develops between the vegetal cortex and cytoplasm is implicated in generating movement. Rhodamine-tubulin was injected into eggs to allow patterns of microtubule movement and polymerisation in the vegetal array to be examined. Time-lapse video microscopy of living eggs showed that mo st of these microtubules move with the vegetal cytoplasm relative to the cortex, at the same speed as cytoplasmic pigment granules. This implies that movement is generated between the microtubules of the vegetal array and the cortex. A few microtubules we re also detected that appeared immobile with respect to the cortex. Rhodamine-tubulin became incorporated into vegetal microtubules when injected at any time during the period of cortical rotation. The newly formed microtubules connected the vegetal array and internal cytoplasm. This indicates that local outward-direct ed polymerisation continues in this region as the cortex translocates. Experiments with low doses of nocodazole showed that this continuing polymerisation does not contribute to the rotation. Concentrations of the drug that prevented tubulin polymerisatio n had no effect on the speed of rotation if applied after the vegetal array had formed. The same doses prevented movement if applied early enough to prevent the formation of the array. These observations support the idea that mechanochemical enzymes assoc iated with the vegetal microtubules translocate the cortex along microtubules anchored in the subcortical cytoplasm.

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Sani, Salihu, Ibrahim Tajo Siraj, Mukhtar Atiku Kurawa, and Siti Nadiah Abdul Halim. "An efficient synthetic route, characterization and antimicrobial evaluation of Co(II), Ni(II), Cu(II) and Zn(II) Schiff base complexes." Bulletin of the Chemical Society of Ethiopia 36, no. 4 (August 30, 2022): 801–13. http://dx.doi.org/10.4314/bcse.v36i4.7.

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ABSTRACT. The synthesis of Schiff base compound derived from 2-hydroxy-3-methoxybenzaldehyde and o-phenylenediamine via solvent-assisted mechanochemical synthesis in the presence of a small amount of dimethylformamide as liquid-assisted solvent was reported. The Co(II), Ni(II), Cu(II) and Zn(II) Schiff base complexes were synthesized and characterized by powder x-ray diffraction, infra-red spectroscopy, differential scanning colorimetry, thermogrametric analysis, energy dispersive X-ray analysis and CHNS/O macro-analysis. According to infrared spectral analysis, a strong band in the spectra of Schiff base at 1617 cm-1 was assigned to the azomethine v(C=N) stretching vibration. In the complexes, it shifted to lower frequency regions, indicating the formation of desired compounds. The DSC thermogram of Schiff base showed a single sharp peak at 158 oC, which is attributed to the melting or the phase transition. As revealed by TGA, the complexes were obtained as solid compounds containing some amounts of water molecules. The powder-XRD analysis showed that the patterns of the synthesized compounds were different from the starting materials, indicating that the starting constituents were changed into product. The antimicrobial activity results for selected bacteria and fungi revealed that complexes have higher activity than the Schiff base. Furthermore, the synthesized compounds were found to be more effective against fungal isolates than those of bacteria. KEY WORDS: Schiff base, Solvent-assisted mechanochemistry, Azomethine, Complexes Bull. Chem. Soc. Ethiop. 2022, 36(4), 801-813. DOI: https://dx.doi.org/10.4314/bcse.v36i4.7

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Chong-Canto, Sayuri, Efrén V. García-Báez, Francisco J. Martínez-Martínez, Angel A. Ramos-Organillo, and Itzia I. Padilla-Martínez. "Mechanochemical Synthesis and Structure of the Tetrahydrate and Mesoporous Anhydrous Metforminium(2+)-N,N′-1,4-Phenylenedioxalamic Acid (1:2) Salt: The Role of Hydrogen Bonding and n→π * Charge Assisted Interactions." Pharmaceutics 12, no. 10 (October 21, 2020): 998. http://dx.doi.org/10.3390/pharmaceutics12100998.

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A new organic salt of metformin, an antidiabetic drug, and N,N′-(1,4-phenylene)dioxalamic acid, was mechanochemically synthesized, purified by crystallization from solution and characterized by single X-ray crystallography. The structure revealed a salt-type crystal hydrate composed of one dicationic metformin unit, two monoanionic units of the acid and four water molecules, namely H2Mf(HpOXA)2∙4H2O. X-ray powder, IR, 13C-CPMAS, thermal and BET adsorption–desorption analyses were performed to elucidate the structure of the molecular and supramolecular structure of the anhydrous microcrystalline mesoporous solid H2Mf(HpOXA)2. The results suggest that their structures, conformation and hydrogen bonding schemes are very similar. To the best of our knowledge, the selective formation of the monoanion HpOXA−, as well as its structure in the solid, is herein reported for the first time. Regular O(δ−)∙∙∙C(δ), O(δ−)∙∙∙N+ and bifacial O(δ−)∙∙∙C(δ)∙∙∙O(δ−) of n→π * charge-assisted interactions are herein described in H2MfA organic salts which could be responsible of the interactions of metformin in biologic systems. The results support the participation of n→π * charge-assisted interactions independently, and not just as a short contact imposed by the geometric constraint due to the hydrogen bonding patterns.

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Wu, E., S. J. Campbell, W. A. Kaczmarek, M. Hofmann, and S. J. Kennedy. "Nanostructured (Co_xFe_{1– x})_3–yO₄ spinel – mechanochemical synthesis." International Journal of Materials Research 94, no. 10 (October 1, 2003): 1127–33. http://dx.doi.org/10.1515/ijmr-2003-0204.

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Abstract The effects of wet-milling mixtures of α-Fe2O3 and cobalt hydroxide Co(OH)2 over a range of Co/Fe ratios for 215 h have been investigated by neutron diffraction and Mössbauer spectroscopy. The starting materials were mixed according to the stoichiometric formula (Co x Fe1 –x )3O4 for values of x = 0.037, 0.071, 0.133, 0.234 and 0.380 (i. e., from ≈ Co0.1Fe2.9O4 to the cobalt spinel CoFe2O4). These studies reveal the formation of a nanostructured, mixed Co–Fe spinel phase with non-stoichiometric composition (Co x Fe1– x )3 –y O4; the defect spinels have refined values x c = 0.04, 0.08 and 0.14 for the mixtures with the lowest Co content (x = 0.037, 0.071 and 0.133) and defect concentrations in the range y ≈ 0.1 –0.2. Both the spinel phase and un-reacted α-Fe2O3 are found to occur in the neutron diffraction patterns and Mössbauer spectra for the high Co content mixtures x = 0.234 and x = 0.380. Rietveld refinements of the neutron data indicate that the Co atoms predominantly occupy the octahedral B sites with vacancies also found to be located on the octahedral B sites. Analyses of the Mössbauer spectra of the milled samples confirm the existence of vacancy defects in the B sites and reveal that the vacancies cause similar effects to those of the Co ions, leading to a higher average charge state per iron atom.

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Lazarevic, Zorica, B. D. Stojanovic, M. J. Romcevic, and N. Z. Romcevic. "Mechanochemical activation assisted synthesis of bismuth Layered-Perovskite Bi4Ti4O12." Science of Sintering 41, no. 1 (2009): 19–26. http://dx.doi.org/10.2298/sos0901019l.

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A powder mixture of Bi2O3 and TiO2, both monoclinic, was mechanochemically treated in a planetary ball mill in air atmosphere for different time, using zirconium balls as the milling medium. Mechanochemical reaction leads to the gradual formation of an amorphous phase. After 1 h of milling the starting oxides were transformed fully a nanocrystalline Bi4Ti4O12 phase. With increasing the milling time from 3 to 12h, the particle size of formed Bi4Ti3O12 did not reduced significantly. That was confirmed by IR and TEM analysis. The electron diffraction pattern indicates that Bi4Ti3O12 crystalline powder is embedded in an amorphous phase of bismuth titanate. Phase composition and atom ratio in BIT ceramics were determined by X-ray diffraction and EDS analysis. After milling for various times the powders were compacted by pressing and isothermal sintering. The dielectric permittivity of the sintered samples significantly depends on the milling time. Sample milled for 12 h and subsequently sintered at 1000?C for 24 h exhibit a hysteresis loop, confirming that the synthesized material possesses ferroelectric properties.

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Raić, Matea, Lara Mikac, Ivan Marić, Goran Štefanić, Marko Škrabić, Marijan Gotić, and Mile Ivanda. "Nanostructured Silicon as Potential Anode Material for Li-Ion Batteries." Molecules 25, no. 4 (February 17, 2020): 891. http://dx.doi.org/10.3390/molecules25040891.

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Commercial micrometer silicon (Si) powder was investigated as a potential anode material for lithium ion (Li-ion) batteries. The characterization of this powder showed the mean particle size of approx.75.2 nm, BET surface area of 10.6 m2/g and average pore size of 0.56 nm. Its band gap was estimated to 1.35 eV as determined using UV-Vis diffuse reflectance spectra. In order to increase the surface area and porosity which is important for Li-ion batteries, the starting Si powder was ball-milled and threatened by metal-assisted chemical etching. The mechanochemical treatment resulted in decrease of the particle size from 75 nm to 29 nm, an increase of the BET surface area and average pore size to 16.7 m2/g and 1.26 nm, respectively, and broadening of the X-ray powder diffraction (XRD) lines. The XRD patterns of silver metal-assisted chemical etching (MACE) sample showed strong and narrow diffraction lines typical for powder silicon and low-intensity diffraction lines typical for silver. The metal-assisted chemical etching of starting Si material resulted in a decrease of surface area to 7.3 m2/g and an increase of the average pore size to 3.44 nm. These three materials were used as the anode material in lithium-ion cells, and their electrochemical properties were investigated by cyclic voltammetry and galvanostatic charge-discharge cycles. The enhanced electrochemical performance of the sample prepared by MACE is attributed to increase in pore size, which are large enough for easy lithiation. These are the positive aspects of the application of MACE in the development of an anode material for Li-ion batteries.

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Journal articles on the topic 'Mechanochemical patterns'

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