Templated nanofiber synthesis via chemical vapor polymerization into liquid crystalline films

Science ◽  
2018 ◽  
Vol 362 (6416) ◽  
pp. 804-808 ◽  
Author(s):  
Kenneth C. K. Cheng ◽  
Marco A. Bedolla-Pantoja ◽  
Young-Ki Kim ◽  
Jason V. Gregory ◽  
Fan Xie ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystalline ◽  
Chemical Vapor ◽  
Low Concentrations ◽  
Wide Range ◽  
Crystalline Films ◽  
Organized Assemblies ◽  
Fibrous Polymer ◽  
Induced Changes ◽  
Lateral Organization

Extrusion, electrospinning, and microdrawing are widely used to create fibrous polymer mats, but these approaches offer limited access to oriented arrays of nanometer-scale fibers with controlled size, shape, and lateral organization. We show that chemical vapor polymerization can be performed on surfaces coated with thin films of liquid crystals to synthesize organized assemblies of end-attached polymer nanofibers. The process uses low concentrations of radical monomers formed initially in the vapor phase and then diffused into the liquid-crystal template. This minimizes monomer-induced changes to the liquid-crystal phase and enables access to nanofiber arrays with complex yet precisely defined structures and compositions. The nanofiber arrays permit tailoring of a wide range of functional properties, including adhesion that depends on nanofiber chirality.

Properties of ER Fluids Comprised of Liquid Crystalline Polymers

1999 ◽  
Vol 13 (14n16) ◽  
pp. 1966-1974 ◽  
Author(s):  
Akio Inoue ◽  
Yoichiroh Ide ◽  
Shyunji Maniwa ◽  
Hiroyuki Yamada ◽  
Hiroji Oda
Keyword(s):  
Liquid Crystal ◽  
Electric Field ◽  
Liquid Crystalline ◽  
Morphological Changes ◽  
Particle Dispersion ◽  
Step Response ◽  
Large Temperature ◽  
Wide Range ◽  
Stress Curve ◽  
Generation Mechanisms

Side-chain liquid crystalline polysiloxanes (LCS) diluted with solvents show a large increase in viscosity and a newtonian flow under an electric field. Two types of solvent-diluted LCSs, A and B, are presented and their properties are described in this paper. Type A shows a large temperature-dependent ER effect a quick response of msec. order to an electric field and a dynamic behavior similar to that of a low molecular weight liquid crystal. Type B shows a stable ER effect throughout a wide range of temperatures up to 150°C, a two-step response of shear stress curve upon application of DC electric field and a micron-sized droplets structure which deforms with the electric field. The generation mechanisms of ER effect on the two types were discussed with the data of dynamic and morphological changes, referring those on a low molecular liquid crystal and a particle dispersion type ER fluid.

scholarly journals Identifying a Unique Communication Mechanism of Thermochromic Liquid Crystal Printing Ink

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 876
Author(s):  
Maja Strižić Jakovljević ◽  
Branka Lozo ◽  
Marta Klanjšek Gunde
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystalline ◽  
Intrinsic Property ◽  
Integrating Sphere ◽  
Thermochromic Liquid Crystal ◽  
Liquid Crystal Material ◽  
Communication Mechanism ◽  
Wide Range ◽  
And Control ◽  
Printing Ink

Thermochromic liquid crystal materials are commonly used in printing inks, opening up a wide range of possible applications. In order to ensure and control the most accurate application, the occurrence of the so-called colour play effect, i.e., the appearance of iridescent (rainbow) colours as a function of temperature, must be determined precisely. For this purpose, the temperature-dependent reflection of a sample must be measured using a spectrometer with an integrating sphere. The same values should be obtained for each sample containing the same thermochromic liquid crystalline material, irrespective of the spectrometer used, integrating sphere, layer thickness and the surface properties of the substrate. To describe this intrinsic property of the thermochromic liquid crystal material, the term communication mechanism might be considered. The research has shown how this mechanism is obtained experimentally.

Photochromic reaction-induced changes of ordering in liquid crystalline films

2008 ◽  
Vol 516 (24) ◽  
pp. 8899-8904 ◽  
Author(s):  
K. Matczyszyn ◽  
A. Chwialkowska ◽  
J. Sworakowski
Keyword(s):  
Liquid Crystalline ◽  
Crystalline Films ◽  
Induced Changes ◽  
Photochromic Reaction

scholarly journals Vanadium Toxicity Induced Changes in Growth, Antioxidant Profiling, and Vanadium Uptake in Pepper (Capsicum annum L.) Seedlings

Horticulturae ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 28
Author(s):  
Muhammad Ahsan Altaf ◽  
Huangying Shu ◽  
Yuanyuan Hao ◽  
Yan Zhou ◽  
Muhammad Ali Mumtaz ◽  
...  
Keyword(s):  
Heavy Metal Contamination ◽  
Leaf Gas Exchange ◽  
Anthropogenic Activities ◽  
Photosynthetic Performance ◽  
Antioxidant Enzyme Activities ◽  
Growth Status ◽  
Low Concentrations ◽  
Wide Range ◽  
Vanadium Toxicity ◽  
Induced Changes

Heavy metal contamination is one of the current serious environmental and agricultural soil issues, and it is mainly due to anthropogenic activities. Vanadium (V) is found in low concentrations in a wide range of plants and is widely distributed in soils. The current study aimed to determine how pepper seedlings responded to various V concentrations, as well as the detrimental effects of V on growth, root morphological traits, photosynthetic performance, reactive oxygen species (ROS), osmolytes production, antioxidant enzyme activities, and V uptake. Pepper seedlings (5 weeks old) were grown in hydroponic culture with six V levels (0, 10, 20, 30, 40, and 50 mg L−1 NH4VO3). After two weeks of V treatment, low level of V (10, 20 mg L−1) enhanced the growth status, conversely higher V (30, 40, and 50 mg L−1) level reduced the growth. The leaf gas exchange elements, pigments molecules, and root growth characteristics are also affected by higher V concentrations. Moreover, V uptake was higher in roots than in the shoot of pepper seedlings. Similarly, osmolytes content, ROS production, and antioxidant enzymes activities were significantly improved under V stress. Concluding, lower V (10, 20 mg L−1) concentration positively affected pepper growth, and higher V (30, 40, and 50 mg L−1) concentration had a detrimental effect on pepper physiological and biochemical mechanisms.

Polarized Fluorescence from Vitrified Liquid Crystalline Films

1996 ◽  
Vol 425 ◽  
Author(s):  
Brooke M. Conger ◽  
H. Shi ◽  
S. H. Chen ◽  
T. Tsutsui
Keyword(s):  
Liquid Crystal ◽  
Linear Polarization ◽  
Order Parameter ◽  
Liquid Crystalline ◽  
Emission Spectra ◽  
Polarized Fluorescence ◽  
Circularly Polarized ◽  
Chiral Nematic ◽  
Polarization Factor ◽  
Crystalline Films

AbstractLinearly and circularly polarized photoluminescence (PL) were observed from neat vitrified liquid crystal (LC) films. Electronic properties of the compounds were investigated through measurement of absorption and emission spectra in solution and in film. The nematic film exhibited a polarization factor (linear polarization) of 2.8 at an order parameter of 0.70, whereas the chiral nematic film gave rise to an absolute dissymmetry factor (circular polarization) of 0.27 at an order parameter of 0.54.

Structural and electronic properties of defects in semiconductors

1995 ◽  
Vol 53 ◽  
pp. 4-5
Author(s):  
J.L. Batstone
Keyword(s):  
Semiconductor Device ◽  
Chemical Vapor ◽  
Misfit Strain ◽  
Organic Chemical ◽  
Extended Defects ◽  
Transmission Electron ◽  
Semiconductor Thin Films ◽  
Wide Range ◽  
Metal Organic ◽  
Film Substrate

The development of growth techniques such as metal organic chemical vapor deposition (MOCVD) and molecular beam epitaxy during the last fifteen years has resulted in the growth of high quality epitaxial semiconductor thin films for the semiconductor device industry. The III-V and II-VI semiconductors exhibit a wide range of fundamental band gap energies, enabling the fabrication of sophisticated optoelectronic devices such as lasers and electroluminescent displays. However, the radiative efficiency of such devices is strongly affected by the presence of optically and electrically active defects within the epitaxial layer; thus an understanding of factors influencing the defect densities is required.Extended defects such as dislocations, twins, stacking faults and grain boundaries can occur during epitaxial growth to relieve the misfit strain that builds up. Such defects can nucleate either at surfaces or thin film/substrate interfaces and the growth and nucleation events can be determined by in situ transmission electron microscopy (TEM).

Triply-periodic nanostructures in surfactant, block copolymer, and biomembrane systems, and simulation of TEMs

1993 ◽  
Vol 51 ◽  
pp. 884-885
Author(s):  
David M. Anderson ◽  
Tomas Landh
Keyword(s):  
Liquid Crystalline ◽  
Diblock Copolymers ◽  
Cubic Phase ◽  
List Type ◽  
Interpenetrating Networks ◽  
Triply Periodic ◽  
Wide Range ◽  
Bicontinuous Cubic ◽  
Phase Liquid ◽  
Dividing Surface

First discovered in surfactant-water liquid crystalline systems, so-called ‘bicontinuous cubic phases’ have the property that hydropnilic and lipophilic microdomains form interpenetrating networks conforming to cubic lattices on the scale of nanometers. Later these same structures were found in star diblock copolymers, where the simultaneous continuity of elastomeric and glassy domains gives rise to unique physical properties. Today it is well-established that the symmetry and topology of such a morphology are accurately described by one of several triply-periodic minimal surfaces, and that the interface between hydrophilic and hydrophobic, or immiscible polymer, domains is described by a triply-periodic surface of constant, nonzero mean curvature. One example of such a dividing surface is shown in figure 5.The study of these structures has become of increasing importance in the past five years for two reasons:1)Bicontinuous cubic phase liquid crystals are now being polymerized to create microporous materials with monodispersed pores and readily functionalizable porewalls; figure 3 shows a TEM from a polymerized surfactant / methylmethacrylate / water cubic phase; and2)Compelling evidence has been found that these same morphologies describe biomembrane systems in a wide range of cells.

Solvent-Free Powder Synthesis and MOF-CVD Thin Films of the Mesoporous Metal-Organic Framework MAF-6

2019 ◽  
Author(s):  
Timothée Stassin ◽  
Ivo Stassen ◽  
Joao Marreiros ◽  
Alexander John Cruz ◽  
Rhea Verbeke ◽  
...  
Keyword(s):  
Vapor Phase ◽  
Metal Organic Framework ◽  
Chemical Vapor ◽  
Uptake Capacity ◽  
Powder Synthesis ◽  
Crystalline Films ◽  
Metal Organic ◽  
Mesoporous Metal ◽  
First Time ◽  
Organic Framework

A simple solvent- and catalyst-free method is presented for the synthesis of the mesoporous metal-organic framework (MOF) MAF-6 (RHO-Zn(eIm)2) based on the reaction of ZnO with 2-ethylimidazole vapor at temperatures ≤ 100 °C. By translating this method to a chemical vapor deposition (CVD) protocol, mesoporous crystalline films could be deposited for the first time entirely from the vapor phase. A combination of PALS and Kr physisorption measurements confirmed the porosity of these MOF-CVD films and the size of the MAF-6 supercages (diam. ~2 nm), in close agreement with powder data and calculations. MAF-6 powders and films were further characterized by XRD, TGA, SEM, FTIR, PDF and EXAFS. The exceptional uptake capacity of the mesoporous MAF-6 in comparison to the microporous ZIF-8 is demonstrated by vapor-phase loading of a molecule larger than the ZIF-8 windows.

Antimicrobial Peptides - Small but Mighty Weapons for Plants to Fight Phytopathogens

2019 ◽  
Vol 26 (10) ◽  
pp. 720-742 ◽  
Author(s):  
Kaushik Das ◽  
Karabi Datta ◽  
Subhasis Karmakar ◽  
Swapan K. Datta
Keyword(s):  
Antimicrobial Peptides ◽  
Durable Resistance ◽  
Defense Responses ◽  
Defense System ◽  
Biotechnological Potential ◽  
Functional Aspects ◽  
Low Concentrations ◽  
Wide Range ◽  
Vital Component ◽  
Pathogen Entry

Antimicrobial Peptides (AMPs) have diverse structures, varied modes of actions, and can inhibit the growth of a wide range of pathogens at low concentrations. Plants are constantly under attack by a wide range of phytopathogens causing massive yield losses worldwide. To combat these pathogens, nature has armed plants with a battery of defense responses including Antimicrobial Peptides (AMPs). These peptides form a vital component of the two-tier plant defense system. They are constitutively expressed as part of the pre-existing first line of defense against pathogen entry. When a pathogen overcomes this barrier, it faces the inducible defense system, which responds to specific molecular or effector patterns by launching an arsenal of defense responses including the production of AMPs. This review emphasizes the structural and functional aspects of different plant-derived AMPs, their homology with AMPs from other organisms, and how their biotechnological potential could generate durable resistance in a wide range of crops against different classes of phytopathogens in an environmentally friendly way without phenotypic cost.

The Influence of Ultra-Low Concentrations of Potassium Anphen on the Bioenergetic Characteristics of Mitochondria

2020 ◽  
Vol 16 (4) ◽  
pp. 537-542
Author(s):  
Zhigacheva Irina ◽  
Volodkin Aleksandr ◽  
Rasulov Maksud
Keyword(s):  
Functional State ◽  
Membrane Lipids ◽  
Biological Effects ◽  
Dose Dependence ◽  
Stress Factors ◽  
Mitochondrial Membranes ◽  
Oxidation Rates ◽  
Pea Seedlings ◽  
Low Concentrations ◽  
Wide Range

Background: One of the main sources of ROS in stress conditions is the mitochondria. Excessive generation of ROS leads to oxidation of thiol groups of proteins, peroxidation of membrane lipids and swelling of the mitochondria. In this regard, there is a need to search for preparationsadaptogens that increase the body's resistance to stress factors. Perhaps, antioxidants can serve as such adaptogens. This work aims at studying the effect of antioxidant; the potassium anphen in a wide range of concentrations on the functional state of 6 day etiolated pea seedlings mitochondria (Pisum sativum L). Methods: The functional state of mitochondria was studied per rates of mitochondria respiration, by the level of lipid peroxidation and study of fatty acid composition of mitochondrial membranes by chromatography technique. Results: Potassium anphen in concentrations of 10-5 - 10-8 M and 10-13-10-16 prevented the activation of LPO in the mitochondrial membranes of pea seedlings, increased the oxidation rates of NAD-dependent substrates and succinate in the respiratory chain of mitochondria that probably pointed to the anti-stress properties of the drug. Indeed, the treatment of pea seeds with the preparation in concentrations of 10-13 M prevented the inhibition of growth of seedlings in conditions of water deficiency. Conclusion: It is assumed that the dose dependence of the biological effects of potassium anphen and the manifestation of these effects in ultra-low concentrations are due to its ability in water solutions to form a hydrate containing molecular ensembles (structures).

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