scholarly journals Structural Characterization of an Archaeal Lipid Bilayer as a Function of Hydration and Temperature

2020 ◽  
Vol 21 (5) ◽  
pp. 1816
Author(s):  
Marta Salvador-Castell ◽  
Bruno Demé ◽  
Philippe Oger ◽  
Judith Peters
Keyword(s):  
Phase Transition ◽  
Relative Humidity ◽  
Lipid Bilayers ◽  
Self Assembly ◽  
Structural Characteristics ◽  
Scattering Length ◽  
Structural Parameters ◽  
Hydrophobic Region ◽  
Lamellar Phases

Archaea, the most extremophilic domain of life, contain ether and branched lipids which provide extraordinary bilayer properties. We determined the structural characteristics of diether archaeal-like phospholipids as functions of hydration and temperature by neutron diffraction. Hydration and temperature are both crucial parameters for the self-assembly and physicochemical properties of lipid bilayers. In this study, we detected non-lamellar phases of archaeal-like lipids at low hydration levels, and lamellar phases at levels of 90% relative humidity or more exclusively. Moreover, at 90% relative humidity, a phase transition between two lamellar phases was discernible. At full hydration, lamellar phases were present up to 70 °C and no phase transition was observed within the temperature range studied (from 25 °C to 70 °C). In addition, we determined the neutron scattering length density and the bilayer’s structural parameters from different hydration and temperature conditions. At the highest levels of hydration, the system exhibited rearrangements on its corresponding hydrophobic region. Furthermore, the water uptake of the lipids examined was remarkably high. We discuss the effect of ether linkages and branched lipids on the exceptional characteristics of archaeal phospholipids.

Characterization of β-cyclodextrin Self-Aggregates for Eugenol Encapsulation

2012 ◽  
Vol 8 (2) ◽  
Author(s):  
Ji-Yeon Chun ◽  
Sung-Kyu You ◽  
Mi-Yeon Lee ◽  
Mi-Jung Choi ◽  
Sang-Gi Min
Keyword(s):  
Relative Humidity ◽  
Self Assembly ◽  
Retention Rate ◽  
Thick Layer ◽  
Storage Duration ◽  
Aggregation Behaviour ◽  
Induced Decomposition ◽  
And Storage ◽  
Oxidation Loss

Abstract The application of β-cyclodextrin(CD)-assisted molecular encapsulation of neutraceutical ingredients, functional food in food products, hydrophobic drugs, and volatile substances helps protect the active ingredients against oxidation, loss of volatile compounds and light-induced decomposition and increases the solubility of hydrophobic medicines. Self-assembly aggregation of CDs has been extensively investigated from the aggregation of native CDs to high-order complex aggregates. The increasing complex order of the aggregates is dependent on some parameters such as pH, temperature, time and concentration. The aim of this study was to investigate the effects of the aggregation behaviour of β-cyclodextrin (CD)-eugenol complexes induced at shaking times on the release characteristic at various relative humidity and storage temperatures. The particle size started to increase after shaking for 8 h at 650 nm, and then, significant aggregation (1,110 nm) was observed after 24 h. The retention rate of eugenol significantly increased according to storage duration under various relative humidity and temperature conditions. Prolonged shaking time enhanced the self-aggregation of β-CD-eugenol complexes resulting in eugenol release behavior due to their effect on the aggregation mechanism, as assessed by TEM observation. The aggregation of β-CD-eugenol complexes could be attributed to the slow release of eugenol owing to the presence of a thick layer of β-CD aggregates.

Age Related Variation in BMD and Trabecular Architecture Differs Between the Proximal Femur and Calcaneus in Men

2011 ◽  
Author(s):  
Hanna Isaksson ◽  
Viktoria Prantner ◽  
Jukka S. Jurvelin
Keyword(s):  
Structural Characteristics ◽  
Structural Parameters ◽  
Fragility Fractures ◽  
Mineral Density ◽  
Predictive Capacity ◽  
Age Related ◽  
Overall Resistance ◽  
Status Differences ◽  
Insight Into

Fragility fractures due to degradation of the bone tissue during aging or development of osteoporosis are responsible for significant morbidity and mortality in elderly patients. A variety of factors contribute to the overall resistance of bones to fracture, e.g. the bone quality. Traditionally, bone mineral density (BMD) as assessed by the dual energy x-ray absorptiometry (DXA) is the gold standard for osteoporosis diagnostics 1. However, BMD alone is insufficient to explain fracture risk in patients 2. Additional characterization of bone structural parameters may provide more insight into the predictive capacity of BMD with respect to bone structural parameters. Further, as various skeletal sites are used to assess bone status, differences in structural characteristics of skeletal sites should be addressed.

Preparation and Characterization of Oligopeptide/M-Pluronic F127 Composite Membranes

2020 ◽  
Vol 996 ◽  
pp. 59-63
Author(s):  
Chuan Jun Xia ◽  
Ping Deng Ming ◽  
Ya Song Hu ◽  
Cong Cong Zhan ◽  
An Duo Zhou ◽  
...  
Keyword(s):  
Self Assembly ◽  
Structural Parameters ◽  
Composite Films ◽  
Composite Membranes ◽  
Intermolecular Forces ◽  
Pluronic F127 ◽  
Scanning Calorimetry ◽  
Dsc Measurements ◽  
Assembly Behavior

In the present study, oligopeptide (TEA) and modified Pluronic F127 (M-Pluronic F127) with different mass fraction composited by intermolecular forces. And the oligopeptide/M-Pluronic F127 composite membranes were prepared and investigated. The structural parameters of the membranes were characterized by fourier transform-infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) measurements. It was found that there had strong interaction between TEA and M-Pluronic F127 and the composite films with different proportions had different surface morphology and thermal stability. The characteristics of the membranes were related to the significant changes of the self-assembly behavior of the TEA modified by M-Pluronic F127.

A Possible Basis for Nondestructive Characterization of Ropes of Nylon 6

1997 ◽  
Vol 503 ◽  
Author(s):  
H. Jiang ◽  
M. K. Davis ◽  
R. K. Eby ◽  
P. Arsenovic
Keyword(s):  
Tensile Strength ◽  
Service Life ◽  
Fiber Diameter ◽  
Structural Parameters ◽  
Crystal Form ◽  
Nylon 6 ◽  
Remaining Service Life ◽  
Nondestructive Characterization ◽  
Fractional Content

ABSTRACTPhysical properties and structural parameters have been measured for ropes of nylon 6 as a function of the number of use operations. The fractional content of the α crystal form, sound velocity, birefringence, tensile strength and length all increase systematically and significantly with increasing the number of use operations. The fractional content of the γ crystal form and fiber diameter decrease with use. These trends indicate that the measurement of such properties and structural parameters, especially the length, provide a possible basis for establishing a reliable, rapid, and convenient nondestructive characterization method to predict the remaining service life of nylon 6 ropes.

Reversible microscale assembly of nanoparticles driven by the phase transition of a thermotropic liquid crystal

2017 ◽  
Author(s):  
Niamh Mac Fhionnlaoich ◽  
Stephen Schrettl ◽  
Nicholas B. Tito ◽  
Ye Yang ◽  
Malavika Nair ◽  
...  
Keyword(s):  
Phase Transition ◽  
Liquid Crystal ◽  
Self Assembly ◽  
Nematic Phase ◽  
Hierarchical Control ◽  
Building Blocks ◽  
Model System ◽  
Microscopic Level ◽  
Reversible Process ◽  
Thermotropic Liquid Crystal

The arrangement of nanoscale building blocks into patterns with microscale periodicity is challenging to achieve via self-assembly processes. Here, we report on the phase transition-driven collective assembly of gold nanoparticles in a thermotropic liquid crystal. A temperature-induced transition from the isotropic to the nematic phase leads to the assembly of individual nanometre-sized particles into arrays of micrometre-sized aggregates, whose size and characteristic spacing can be tuned by varying the cooling rate. This fully reversible process offers hierarchical control over structural order on the molecular, nanoscopic, and microscopic level and is an interesting model system for the programmable patterning of nanocomposites with access to micrometre-sized periodicities.

Small angle X-ray scattering study of porosity variation in a styrene-divinylbenzene copolymer

1981 ◽  
Vol 46 (7) ◽  
pp. 1675-1681 ◽  
Author(s):  
Josef Baldrian ◽  
Božena N. Kolarz ◽  
Henrik Galina
Keyword(s):  
Small Angle ◽  
Structural Parameters ◽  
Two Phase ◽  
X Ray ◽  
Porosity Variation ◽  
Swelling Agent ◽  
X Ray Scattering ◽  
Styrene Divinylbenzene ◽  
Ray Scattering

Porosity variations induced by swelling agent exchange were studied in a styrene-divinylbenzene copolymer. Standard methods were used in the characterization of copolymer porosity in the dry state and the results were compared with related structural parameters derived from small angle X-ray scattering (SAXS) measurements as developed for the characterization of two-phase systems. The SAXS method was also used for porosity determination in swollen samples. The differences in the porosity of dry samples were found to be an effect of the drying process, while in the swollen state the sample swells and deswells isotropically.

scholarly journals Electrochemical Properties of Lipid Membranes Self-Assembled from Bicelles

Membranes ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 11
Author(s):  
Damian Dziubak ◽  
Kamil Strzelak ◽  
Slawomir Sek
Keyword(s):  
Electrochemical Properties ◽  
Self Assembly ◽  
Lipid Membranes ◽  
Lipid Membrane ◽  
Membrane Resistance ◽  
Electrochemical Characteristics ◽  
Freeze Thaw ◽  
Lipid Films ◽  
Supported Lipid Membranes

Supported lipid membranes are widely used platforms which serve as simplified models of cell membranes. Among numerous methods used for preparation of planar lipid films, self-assembly of bicelles appears to be promising strategy. Therefore, in this paper we have examined the mechanism of formation and the electrochemical properties of lipid films deposited onto thioglucose-modified gold electrodes from bicellar mixtures. It was found that adsorption of the bicelles occurs by replacement of interfacial water and it leads to formation of a double bilayer structure on the electrode surface. The resulting lipid assembly contains numerous defects and pinholes which affect the permeability of the membrane for ions and water. Significant improvement in morphology and electrochemical characteristics is achieved upon freeze–thaw treatment of the deposited membrane. The lipid assembly is rearranged to single bilayer configuration with locally occurring patches of the second bilayer, and the number of pinholes is substantially decreased. Electrochemical characterization of the lipid membrane after freeze–thaw treatment demonstrated that its permeability for ions and water is significantly reduced, which was manifested by the relatively high value of the membrane resistance.

scholarly journals Coupled Fluid–Solid Numerical Simulation for Flow Field Characteristics and Supporting Performance of Flexible Support Cylindrical Gas Film Seal

Aerospace ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 97
Author(s):  
Junfeng Sun ◽  
Meihong Liu ◽  
Zhen Xu ◽  
Taohong Liao ◽  
Xiangping Hu ◽  
...  
Keyword(s):  
Flow Field ◽  
Film Thickness ◽  
Fluid Dynamic ◽  
Structural Characteristics ◽  
Structural Parameters ◽  
Equivalent Stress ◽  
Three Dimensional ◽  
High Rotational Speed ◽  
Flexible Support ◽  
Flow Field Characteristics

A new type of cylindrical gas film seal (CGFS) with a flexible support is proposed according to the working characteristics of the fluid dynamic seal in high-rotational-speed fluid machinery, such as aero-engines and centrifuges. Compared with the CGFS without a flexible support, the CGFS with flexible support presents stronger radial floating characteristics since it absorbs vibration and reduces thermal deformation of the rotor system. Combined with the structural characteristics of a film seal, an analytical model of CGFS with a flexible wave foil is established. Based on the fluid-structure coupling analysis method, the three-dimensional flow field of a straight-groove CGFS model is simulated to study the effects of operating and structural parameters on the steady-state characteristics and the effects of gas film thickness, eccentricity, and the number of wave foils on the equivalent stress of the flexible support. Simulation results show that the film stiffness increases significantly when the depth of groove increases. When the gas film thickness increases, the average equivalent stress of the flexible support first decreases and then stabilizes. Furthermore, the number of wave foils affects the average foils thickness. Therefore, when selecting the number of wave foils, the support stiffness and buffer capacity should be considered simultaneously.

scholarly journals Exploiting the Amazing Diversity of Natural Source-Derived Polysaccharides: Modern Procedures of Isolation, Engineering, and Optimization of Antiviral Activities

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 136
Author(s):  
Bimalendu Ray ◽  
Martin Schütz ◽  
Shuvam Mukherjee ◽  
Subrata Jana ◽  
Sayani Ray ◽  
...  
Keyword(s):  
Structural Characteristics ◽  
Antiviral Drug ◽  
Natural Source ◽  
Target Interaction ◽  
Charge Densities ◽  
Linkage Pattern ◽  
Naturally Occurring ◽  
Antiviral Activities ◽  
One Step

Naturally occurring polysaccharide sulfates are highly diverse, owning variations in the backbone structure, linkage pattern and stereochemistry, branching diversity, sulfate content and positions of sulfate group(s). These structural characteristics bring about diverse sulfated polymers with dissimilar negative charge densities and structure–activity relationships. Herein, we start with a short discussion of techniques needed for extraction, purification, chemical sulfation, and structural characterization of polysaccharides. Processes of isolation and sulfation of plant-derived polysaccharides are challenging and usually involve two steps. In this context, we describe an integrated extraction-sulfation procedure that produces polysaccharide sulfates from natural products in one step, thereby generating additional pharmacological activities. Finally, we provide examples of the spectrum of natural source-derived polysaccharides possessing specific features of bioactivity, in particular focusing on current aspects of antiviral drug development and drug–target interaction. Thus, the review presents a detailed view on chemically engineered polysaccharides, especially sulfated derivatives, and underlines their promising biomedical perspectives.

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