scholarly journals Synthesis of Half-Sphere/Half-Funnel-Shaped Silica Structures by Reagent Localization and the Role of Water in Shape Control

2016 ◽  
Vol 22 (52) ◽  
pp. 18700-18704 ◽  
Author(s):  
Panos Datskos ◽  
Georgios Polizos ◽  
David A. Cullen ◽  
Mahabir Bhandari ◽  
Jaswinder Sharma
Keyword(s):  
Shape Control

scholarly journals Synthesis of Platinum Nanocrystals within Iodine Ions Mediated

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Jiamao Li ◽  
Jingwei Hou ◽  
Yu Gong ◽  
Chengjian Xiao ◽  
Lei Yue ◽  
...  
Keyword(s):  
Shape Control ◽  
Growth Process ◽  
Growth Stage ◽  
Nucleation Stage ◽  
Platinum Nanocrystals ◽  
High Resolution Tem ◽  
Pt Nanocrystals ◽  
High Concentrations ◽  
Insight Into

A liquid-phase reducing method of synthesizing Pt nanocrystals was demonstrated, and dendrite-, cube-, and cuboctahedron-shaped Pt nanocrystals (NCs) with well-defined monomorphic were successfully synthesized through iodine ions mediated with the CTAB agent. When the KI concentration was increased to thirty times of K2PtCl4 at the nucleation stage, the high-quality Pt nanodendrites could be obtained. However, no matter how many KI were added at the growth age, only cube- and cuboctahedron-shaped Pt nanocrystals formed. The results of high-resolution TEM, EDX, and XRD indicated that the size and shape of Pt NCs could be turned by changing the concentration and time of KI. In the nucleation stage, it might be due to that some iodine ions adsorb on the surfaces of Pt NCs, which probably cause the rapid growth process resulting in the formation of Pt nanodendrites. In the growth stage, although high concentrations of I− ions could contribute to the shape control and generate bigger particles of Pt NCs, small Pt particles do not grow into dendrites. The insight into the role of I− ions in synthesis of Pt NCs reported here provided a viewpoint for clearly understanding the formation mechanism of anisotropic platinum nanostructures.

Altering the cellular mechanical force balance results in integrated changes in cell, cytoskeletal and nuclear shape

1992 ◽  
Vol 103 (4) ◽  
pp. 1215-1222 ◽  
Author(s):  
J.R. Sims ◽  
S. Karp ◽  
D.E. Ingber
Keyword(s):  
Shape Control ◽  
Nuclear Shape ◽  
Force Balance ◽  
Dependent Manner ◽  
Integrin Receptors ◽  
Permeabilized Cells ◽  
Capillary Endothelial Cells ◽  
Shape Determination ◽  
Dose Dependent

Studies were carried out with capillary endothelial cells cultured on fibronectin (FN)-coated dishes in order to analyze the mechanism of cell and nuclear shape control by extracellular matrix (ECM). To examine the role of the cytoskeleton in shape determination independent of changes in transmembrane osmotic pressure, membranes of adherent cells were permeabilized with saponin (25 micrograms/ml) using a buffer that maintains the functional integrity of contractile microfilaments. Real-time videomicroscopic studies revealed that addition of 250 microM ATP resulted in time-dependent retraction and rounding of permeabilized cells and nuclei in a manner similar to that observed in intact living cells following detachment using trypsin-EDTA. Computerized image analysis confirmed that permeabilized cells remained essentially rigid in the absence of ATP and that retraction was stimulated in a dose-dependent manner as the concentration of ATP was raised from 10 to 250 microM. Maximal rounding occurred by 30 min with projected cell and nuclear areas being reduced by 69 and 41%, respectively. ATP-induced rounding was also accompanied by a redistribution of microfilaments resulting in formation of a dense net of F-actin surrounding retracted nuclei. Importantly, ATP-stimulated changes in cell, cytoskeletal, and nuclear form were prevented in permeabilized cells using a synthetic myosin peptide (IRICRKG) that has been previously shown to inhibit actomyosin filament sliding in muscle. In contrast, both the rate and extent of cell and nuclear rounding were increased in permeabilized cells exposed to ATP when the soluble FN peptide, GRGDSP, was used to dislodge immobilized FN from cell surface integrin receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Distributed Versus Concentrated Flexibility in Shape Control of Lifting Surfaces: The “Belt-Rib” Structural Concept

1999 ◽  
Author(s):  
Lucio Flavio Campanile ◽  
Delf Sachau
Keyword(s):  
Shape Control ◽  
Aircraft Design ◽  
Experimental Tests ◽  
Structural Flexibility ◽  
Short Introduction ◽  
Structural Concept ◽  
Structure Adaptation ◽  
Structure Geometry ◽  
Lifting Surfaces

Abstract The “mechatronic” way of dealing with the issue of structure geometry control, based on mechanical systems with hinges, bearing and discrete actuators, cannot easily cope with the strict requirements of aircraft design. In this paper a “structronic” concept for airfoils with variable camber is presented, in which the desired geometry changes are achieved through structural flexibility and no moveable parts are needed. A short introduction to the “structronic” approach to structure adaptation in general and to airfoil shape control in particular opens the paper, with some emphasis on the role of solid-state actuators. The description of the new structural concept (the belt-rib concept) follows, with the application to the case of a landing flap with variable camber. Some results of FEM simulations as well as of experimental tests on different prototypes — one of them equipped with shape memory wires as actuators — are also included in the paper. The results provide a first feasibility proof of the new concept and encourage further work.

The role of glutathione on shape control and photoelectrical property of cadmium sulfide nanorod arrays

2013 ◽  
Vol 393 ◽  
pp. 58-65 ◽  
Author(s):  
Chunyan Yang ◽  
Sheng Liu ◽  
Mingrun Li ◽  
Xiuli Wang ◽  
Jian Zhu ◽  
...  
Keyword(s):  
Cadmium Sulfide ◽  
Shape Control ◽  
Nanorod Arrays ◽  
Photoelectrical Property

scholarly journals Formation of trigons in a metal–organic framework: The role of metal–organic polyhedron subunits as meta-atoms

2019 ◽  
Vol 10 (24) ◽  
pp. 6157-6161 ◽  
Author(s):  
Jiyoung Lee ◽  
Jae Sun Choi ◽  
Nak Cheon Jeong ◽  
Wonyoung Choe
Keyword(s):  
Shape Control ◽  
Organic Materials ◽  
Metal Organic Framework ◽  
Metal Organic ◽  
Organic Framework

Shape control of metal–organic materials on the meso- and macroscale has been an important theme due to emerging properties.

scholarly journals Timing matters: the underappreciated role of temperature ramp rate for shape control and reproducibility of quantum dot synthesis

Nanoscale ◽  
2012 ◽  
Vol 4 (12) ◽  
pp. 3625 ◽  
Author(s):  
William J. Baumgardner ◽  
Zewei Quan ◽  
Jiye Fang ◽  
Tobias Hanrath
Keyword(s):  
Quantum Dot ◽  
Shape Control ◽  
Ramp Rate ◽  
Temperature Ramp

scholarly journals Understanding the Role of AgNO3 Concentration and Seed Morphology to Achieve Tunable Shape Control in Gold Nanostars

2018 ◽  
Author(s):  
Supriya Atta ◽  
Laura Fabris
Keyword(s):  
Shape Control ◽  
Experimental Studies ◽  
Seed Morphology ◽  
High Yield ◽  
Metallic Silver ◽  
High Concentration ◽  
Gold Nanostars ◽  
Triton X ◽  
Branched Nanostructures

<div>Gold nanostars are one of the most fascinating anisotropic nanoparticles. Nanostar morphology can be controlled by changing various synthetic parameters; however, the detailed</div><div>growth mechanisms are not fully understood. Herein, we investigate this process in six-branched nanostars, focusing first on the properties of the single crystalline seed, which evolves to include penta-twinned defects as the gateway to anisotropic growth into 6-branched nanostars. In particular, we report on a high-yield seed-mediated protocol for the synthesis of these particles with high monodispersity in the presence of Triton-X, ascorbic acid, and AgNO3. Detailed</div><div>spectroscopic and microscopic analyses have allowed the identification of several key intermediates in the growth process, revealing that it proceeds via penta-twinned intermediate seeds. Importantly, we report the first experimental evidence tracking the location of silver with</div><div>sub-nanometer resolution and prove its role as stabilizing agent in these highly branched nanostructures. Our results indicate that metallic silver on the spikes stabilizes the nanostar morphology, and that the remaining silver, present when AgNO3 is added at high concentration, deposits on the core and between the base of neighboring spikes. Importantly, we also demonstrate the possibility to achieve monodispersity, reproducibility, and tunability in colloidal gold nanostars that are substantially higher than previously reported, which could be leveraged to carry out holistic computational-experimental studies to understand, predict, and tailor their plasmonic response.</div><div><br></div>

Abstract 51: Nucleostemin Induced by Pim-1 Kinase Is Critical to Maintain Pluripotency and Enhance Regenerative Potential of Cardiac Progenitor Cells

2012 ◽  
Vol 111 (suppl_1) ◽  
Author(s):  
Nirmala Hariharan ◽  
Anya Y Joyo ◽  
Kaitlen M Samse ◽  
Daniele Avitabile ◽  
Brandi Bailey ◽  
...  
Keyword(s):  
Progenitor Cells ◽  
Shape Control ◽  
Kinase Inhibitor ◽  
Cardiac Regeneration ◽  
Stem Cell Marker ◽  
Cardiac Progenitor Cells ◽  
Protein Levels ◽  
Regulation Of Cell Cycle ◽  
Factor C

Myocardial regeneration and repair in response to injury are governed in part by cell survival, proliferation and pluripotency. Proliferation and survival in cardiac progenitor cells (CPCs) are mediated by Pim-1, a serine threonine kinase, and nucleostemin (NS), a nucleolar stress sensor protein. The role of NS in regulating CPC pluripotency and the molecular mechanism of NS induction and action is largely unknown. The hypothesis of the study is that NS, induced by Pim-1 mediated stabilization of transcription factor c-Myc is critical to maintain CPC pluripotency and inhibits senescence. NS and c-Myc protein levels are increased in cultured CPCs overexpressing Pim-1 (3.1 and 5.5 fold, p<0.01) while knockdown of Pim-1 using sh-RNA decreases c-Myc and NS expression (-60%, -54%, p<0.05), similar to effects mediated by a Pim-1 kinase inhibitor (p<0.01), indicating that Pim-1 regulates both c-Myc and NS. c-Myc is necessary and sufficient for NS regulation, as indicated by the increase (3.1 fold, p<0.01) and decrease (-60.2%, p<0.01) in NS expression upon lentiviral mediated over-expression or knockdown of c-Myc, respectively. Regulation of NS promoter by c-Myc is evident from loss of GFP expression and fluorescence following knock down of c-Myc in CPCs isolated from transgenic mice expressing eGFP driven by the NS promoter. The role of NS in regulating CPC pluripotency is determined by silencing NS. Change in morphology (flat, round cells vs spindle shape control CPCs), decreased expression of stem cell marker c-Kit (-55%, p<0.05), up-regulation of cell cycle inhibitors p53 and p16 (4.2, 3.8 fold, p<0.01) and decreased proliferation (p<0.05) result from loss of NS in CPCs, suggestive of increased senescence and loss of pluripotency. NS-mediated regulation of CPC senescence is p53 dependent, as silencing p53 reverses CPC morphology and pluripotency lost by NS depletion. In conclusion, NS which is induced downstream of Pim-1 kinase maintains pluripotency and enhances regenerative potential in CPCs. These findings are consistent with cumulative evidence that Pim-1 induced cardiac regeneration is mediated in part by NS, providing an additional mechanistic basis for benefits of genetic engineering with Pim-1 to enhance NS expression in cardiac stem cells.

scholarly journals Size/shape control of gold nanoparticles synthesized by alternating current glow discharge over liquid: the role of pH

2019 ◽  
Vol 6 (9) ◽  
pp. 095074 ◽  
Author(s):  
Phuoc Van Thai ◽  
Shinnosuke Abe ◽  
Kenichiro Kosugi ◽  
Nobuo Saito ◽  
Kazumasa Takahashi ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Glow Discharge ◽  
Shape Control ◽  
Alternating Current
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