Perturbation of lecithin bilayer structure by globoside

1976 ◽  
Vol 54 (3) ◽  
pp. 209-218 ◽  
Author(s):  
D. O. Tinker ◽  
L. Pinteric ◽  
J. C. Hsia ◽  
R. P. Rand
Keyword(s):  
Electron Microscopy ◽  
Phase Transition ◽  
Lipid Bilayers ◽  
Esr Spectroscopy ◽  
Repulsive Force ◽  
Spectroscopic Techniques ◽  
Bilayer Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Spin Resonance

The ultrastructure of aggregates formed by mixtures of pig erythrocyte lecithin, cholesterol and globoside in aqueous systems was studied by electron microscopy and X-ray diffraction. Globoside and lecithin in up to equimolar amounts formed a lamellar mesophase, although the structure of the lamellae was perturbed. Mixtures containing excess globoside formed complex tubular or reticular aggregates. Cholesterol appeared to promote mixing of lecithin and globoside. The flexibility gradient of the hydrocarbon (hc) region of the lipid bilayers was studied using electron spin resonance (esr) spectroscopy of various nitroxide-labelled stearic acid probes. Globoside in equimolar amounts greatly perturbed the order parameters of lecithin bilayers, reducing the fluidity of the hc region and flattening the flexibility gradient near the polar (p) surface. The effect of globoside on lecithin–cholesterol bilayers was not so pronounced, since the latter was already more ordered than lecithin bilayers. A phase transition of pure globoside at 55 °C, involving 'melting' of the hc chains was also detected using X-ray and esr spectroscopic techniques. The interbilayer spacing, dw, of equimolar lecithin–globoside lamellar phase increased by 42% from that of lecithin bilayers, indicating that the glycolipid p group may increase the net repulsive force between bilayers, as was previously predicted theoretically.

Structural Characterization of Gallbladder Stones Using Energy Dispersive X-ray Spectroscopy and X-ray Diffraction

2018 ◽  
Vol 21 (7) ◽  
pp. 495-500 ◽  
Author(s):  
Hassan A. Almarshad ◽  
Sayed M. Badawy ◽  
Abdalkarem F. Alsharari
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Energy Dispersive ◽  
Spectroscopic Techniques ◽  
X Ray Diffraction ◽  
Major Health Problem ◽  
X Ray ◽  
Gallbladder Stones ◽  
Pure Cholesterol ◽  
Scanning Electron

Aim and Objective: Formation of the gallbladder stones is a common disease and a major health problem. The present study aimed to identify the structures of the most common types of gallbladder stones using X-ray spectroscopic techniques, which provide information about the process of stone formation. Material and Method: Phase and elemental compositions of pure cholesterol and mixed gallstones removed from gallbladders of patients were studied using energy-dispersive X-ray spectroscopy combined with scanning electron microscopy analysis and X-ray diffraction. Results: The crystal structures of gallstones which coincide with standard patterns were confirmed by X-ray diffraction. Plate-like cholesterol crystals with laminar shaped and thin layered structures were clearly observed for gallstone of pure cholesterol by scanning electron microscopy; it also revealed different morphologies from mixed cholesterol stones. Elemental analysis of pure cholesterol and mixed gallstones using energy-dispersive X-ray spectroscopy confirmed the different formation processes of the different types of gallstones. Conclusion: The method of fast and reliable X-ray spectroscopic techniques has numerous advantages over the traditional chemical analysis and other analytical techniques. The results also revealed that the X-ray spectroscopy technique is a promising technique that can aid in understanding the pathogenesis of gallstone disease.

W-Doped VO2 (M) with Tunable Phase Transition Temperature

2013 ◽  
Vol 320 ◽  
pp. 483-487 ◽  
Author(s):  
Ming Li ◽  
Deng Bing Li ◽  
Jing Pan ◽  
Guang Hai Li
Keyword(s):  
Electron Microscopy ◽  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Variable Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Infrared Transmittance ◽  
Transmission Electron ◽  
Potential Applications

W-doped VO2 (B) nanoneedles were successfully synthesized by solgel combing with hydrothermal treatment, in which the polyethylene glycol (PEG) was used as both surfactant and reducing. The metastable VO2 (B) was completely transformed to thermochromic VO2 (M) after annealing at high purity N2 atmosphere. The DSC results exhibit a strong crystallographic transition, and the phase transition temperature of VO2 (M) can be reduced to about 38 °C by W-doping. Field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM) were used to characterize the morphology and crystalline structure of the samples. The variable-temperature infrared transmittance spectra of VO2 (M) demonstrate their potential applications in energy saving field.

Metal-Insulator and Structural Phase Transition Observed by ESR Spectroscopy and X-Ray Diffraction inKC60

2001 ◽  
Vol 86 (19) ◽  
pp. 4346-4349 ◽  
Author(s):  
C. Coulon ◽  
A. Pénicaud ◽  
R. Clérac ◽  
R. Moret ◽  
P. Launois ◽  
...  
Keyword(s):  
Phase Transition ◽  
Structural Phase Transition ◽  
Esr Spectroscopy ◽  
Structural Phase ◽  
X Ray Diffraction ◽  
Metal Insulator ◽  
X Ray

scholarly journals Effects of annealing parameters on phase, structure and thermochromic properties of VO2 (M) derived from nanostructured VO2(B)

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Hamdi Muhyuddin Barra ◽  
Soo Kien Chen ◽  
Nizam Tamchek ◽  
Zainal Abidin Talib ◽  
Oon Jew Lee ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Phase Transition ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Sem Images ◽  
X Ray ◽  
Thermogravimetric Analyzer ◽  
Different Temperatures ◽  
Thermochromic Properties ◽  
Scanning Electron

Abstract Synthesis of thermochromic VO2 (M) was successfully done by annealing hydrothermally-prepared VO2 (B) at different temperatures and times. Conversion of the metastable VO2 (B) to the thermochromic VO2 polymorph was studied using thermogravimetric analyzer (TGA) under N2 atmosphere. Moreover, the phase and morphology of the synthesized samples were studied using X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM), respectively. Accordingly, the XRD scans of all the annealed samples exhibited the presence of monoclinic VO2 (M), while the FE-SEM images of the samples showed the formation of nanorods and nanospheres, particularly those heated at high temperatures (650 °C and 700 °C). Meanwhile, differential scanning calorimetry (DSC) was used to measure the phase transition temperature (τc), hysteresis, and enthalpy of the prepared VO2. Based on these results, all samples displayed a τc of about 66 °C. However, the hysteresis was high for the samples annealed at lower temperatures (550 °C and 600 °C), while the enthalpy was very low for samples heated at lower annealing time (1.5 h and 1 h). These findings showed that crystallinity and nanostructure formation affected the thermochromic properties of the samples. In particular, the sample annealed at 650 °C showed better crystallinity and improved thermochromic behavior.

Thermotropic lipid clustering in endoplasmic reticulum membranes of tetrahymena

1978 ◽  
Vol 36 (2) ◽  
pp. 284-285
Author(s):  
F. Wunderlich ◽  
W. Kreutz
Keyword(s):  
Electron Microscopy ◽  
Nuclear Magnetic Resonance ◽  
Endoplasmic Reticulum ◽  
Proton Nuclear Magnetic Resonance ◽  
Resonance Fluorescence ◽  
Total Lipids ◽  
X Ray Diffraction ◽  
X Ray ◽  
Spin Resonance ◽  
Microsomal Membranes

Freeze-etch electron microscopy detects lipid-protein-segregations in endoplasmic reticulum membranes directly within Tetrahymena cells. This manifests in the emergence of smooth areas on the fracture faces at ˜12°C upon cooling the cells from their suboptimal growth temperature of 18°C to 0°C (Figs.1,2). The membrane-intercalating-particles do not become laterally aggregated, but rather appear to be displaced perpendicularly to the membrane plane. Our previous studies using electron spin resonance, fluorescence spectroscopy, proton nuclear magnetic resonance, and differential thermal calorimetry have indicated that these lipid-protein-segregations are induced by a thermotropic lateral lipid clustering.In order to support this suggestion we have now analyzed the thermotropism of the lipids gxtracted from microsomal membranes isolated from cells grov/n at 18°C by wide- and small-angle X-ray diffraction. Our data show that total lipids undergo a broad thermotropic fluid→ ordered phase separation (Figs. 3-5).

Phase Transition and Electrical Properties of Ba0.8Sr0.2TiO3: Comparison of Different Preparation Techniques

2017 ◽  
Vol 866 ◽  
pp. 287-290
Author(s):  
Thanawat Kytae ◽  
Krit Sutjarittangtham ◽  
Theerapol Thurakitseree ◽  
Wilaiwan Leenakul
Keyword(s):  
Electron Microscopy ◽  
Phase Transition ◽  
Electrical Properties ◽  
Molten Salt ◽  
Preparation Technique ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lcr Meter ◽  
Preparation Techniques ◽  
Scanning Electron

This research studied the effect of the different preparation technique on phase transition and electrical properties of Ba0.8Sr0.2TiO3. The samples compared 3 preparation technique, there are conventional mix-oxide, molten-salt and seed-induced method. The samples prepared by molten-salt calcined at 800 °C, the samples prepared by conventional mix-oxide and seed-induced method was calcined at 1200 °C for 3 h. All of samples sintered at 1400 °C for 3 h. The phase formation and morphology of samples were characterized via X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The dielectric properties of the samples were measurement by LCR-meter.

The fcc to hcp transition induced by mechanical deformations in the Ni–Ru system

1992 ◽  
Vol 7 (9) ◽  
pp. 2412-2417 ◽  
Author(s):  
A. Van Neste ◽  
A. Lamarre ◽  
M.L. Trudeau ◽  
R. Schulz
Keyword(s):  
Electron Microscopy ◽  
Phase Transition ◽  
Thermal Analysis ◽  
Transition Point ◽  
Structural Transition ◽  
Crystalline Solid ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mechanical Deformations ◽  
Transmission Electron

The structural transition between the metastable fcc and hcp crystalline solid solutions in the Ni–Ru system has been studied as a function of composition using the mechanical alloying technique. At the transition point, the spacings between the close-packed planes of the metastable fcc and hcp phases are the same. No amorphization is observed at the interfaces. This mechanically induced phase transition has been studied by x-ray diffraction, transmission electron microscopy, and differential thermal analysis.

Effect of Cooling Rates on the Solidification and Microstructure of Rapidly Solidified Mg70.8Zn28Nd1.2 Quasicrystal Alloy

2017 ◽  
Vol 898 ◽  
pp. 246-253
Author(s):  
Xing Jing Ge ◽  
Xin Ying Teng ◽  
Shu Min Xu ◽  
Jin Yang Zhang
Keyword(s):  
Electron Microscopy ◽  
Phase Transition ◽  
Thermal Analysis ◽  
Energy Dispersive Spectrometer ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Cooling Rates ◽  
X Ray ◽  
Rapidly Solidified ◽  
Scanning Electron

The influence of cooling rates on the solidification and microstructure of rapidly solidified quasicrystal alloy Mg70.8Zn28Nd1.2(at.%) was investigated. The microstructure, phase constitution, phase transition and phase structure of the alloys were examined by means of scanning electron microscopy, x-ray diffraction, energy dispersive spectrometer, differential scanning calorimetry. The experimental results showed that the phase composition of as-cast Mg70.8Zn28Nd1.2 alloy includes quasicrystal I-phase and Mg7Zn3 phase. For the rapidly solidified alloy ribbons, when the speed is not higher than 400 r/min, the microstructure includes I-phase, Mg7Zn3 phase and α-Mg phase. When the speed is at the range of 400-2000r/min, the Mg7Zn3 phase disappears and only quasicrystal with α-Mg phase exist. With the increase of cooling rate, the grain size decreases and there are a large number of microcrystals in the microstructure. When the speed reaches higher than 2500 r/min, amorphous phase appeared. Differential thermal analysis showed that quasicrystal exist at about 340°C.

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