scholarly journals Synthesis, Structural, Electrical, and Thermal Studies of ( and ) Ferroelectric Ceramics

ISRN Ceramics ◽  
2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Shiv K. Barbar ◽  
M. Roy
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Thermal Studies ◽  
Activation Energies ◽  
Ferroelectric Ceramics ◽  
Scanning Calorimetry ◽  
Conventional Solid State Reaction ◽  
Modulated Differential Scanning Calorimetry ◽  
Orthorhombic Crystal Structure

The polycrystalline ceramic samples of lead barium niobate with general formula ( and 0.4) were prepared by conventional solid state reaction method. The room temperature X-ray diffraction patterns reveal that both of the samples have orthorhombic crystal structure with space group Cm2m. The dielectric constant and dissipation factor were measured as a function of frequency (100 Hz-2 MHz) and temperature (RT-660K). The DC electrical conductivity of both the samples was measured from RT to 660 K. The activation energies calculated from log σ versus 1000/T curves in ferroelectric phase of the compounds are 1.09 eV for pure () sample and 1.36 eV for Ba-substituted () sample. The values of activation energies show that the substitution of Ba2+ ion on Pb2+ ion site increases the resistivity of pure PbNb2O6 () ceramic. The modulated differential scanning calorimetry (MDSC) has been used to investigate the phase transition temperature of both the compounds and also to see the effect of Ba2+ ion substitution on the phase transition temperature, specific heat, and other thermal parameters of the compound.

Bilayer stabilizing peptides and the inhibition of viral infection: antimeasles activity of carbobenzoxy-Ser-Leu-amide

1987 ◽  
Vol 7 (9) ◽  
pp. 745-749 ◽  
Author(s):  
Richard M. Epand ◽  
Thomas J. Lobl ◽  
H. E. Renis
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Measles Virus ◽  
Cytopathic Effect ◽  
Hexagonal Phase ◽  
Vero Cells ◽  
Time Parameter ◽  
Scanning Calorimetry ◽  
Hplc Retention Time

A number of carbobenzoxy-dipeptide-amides raise the bilayer to hexagonal phase transition temperature of dielaidoylphosphatidylethanolamine (stabilizes the bilayer). The potency of the peptides in stabilizing the bilayer phase is Z-Tyr-Leu-NH2>Z-Gly-Phe-NH2>Z-Ser-Leu-NH2>Z-Gly-Leu-NH2>Z-Gly-Gly-NH2. A linear correlation was found between the respective HPLC retention time parameter k′ for the peptide and the slope of the bilayer stabilization curve determined with model membranes by differential scanning calorimetry. One dipeptide, Z-Ser-Leu-NH2, reduces measles virus cytopathic effect (CPE) in Vero cells. The mechanism by which this peptide reduces the CPE is not known, although some peptides which raise the bilayer to hexagonal phase transition temperature of phospholipids inhibit membrane fusion.

Liquid–solid transition of water confined in nanoporous titanium dioxide

2016 ◽  
Vol 30 (19) ◽  
pp. 1650250
Author(s):  
Xin Gao ◽  
Qiang Wang ◽  
Gang Sun ◽  
Chenxi Li ◽  
Lin Hu
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Titanium Dioxide ◽  
Transition Temperature ◽  
Pore Size ◽  
Phase Transition Temperature ◽  
Porous Titanium ◽  
Molar Enthalpy ◽  
Scanning Calorimetry ◽  
Filling Fraction

In this work, we performed differential scanning calorimetry (DSC) experiments to investigate the phase transition temperature and the molar enthalpy of the absorbed water confined in porous titanium dioxide. The porous titanium dioxide with three different pore size distribution and different filling fraction of the absorbed water were examined. We found that both the pore size of the examined samples and the filling fraction of the absorbed water affected the water’s phase transition temperature and its molar enthalpy.

Study on the Microstructure and Storage Heat Performance of Mg-25Al-15Zn-xCu Alloys

2015 ◽  
Vol 1120-1121 ◽  
pp. 1104-1108
Author(s):  
Hong Yan Wen ◽  
Xiao Ming Fan ◽  
Xiao Min Cheng
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Change ◽  
Latent Heat ◽  
Phase Transition Temperature ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Optical Microstructure ◽  
Solid Solution Matrix ◽  
And Storage

With the help of optical microstructure(OM), X-ray diffraction(XRD) and differential scanning calorimetry(DSC), the microstructure and storage heat performance of Mg-based phase change thermal storage alloys were investigated.The results show that the microstructure of Mg-25Al-15Zn-xCu (x=0, 2%, 8% and 14%, respectivly) alloys are mainly composed of primary crystal α (Mg) solid solution matrix, β-Mg17Al12, CuZn, MgAl2Cu and Mg32(Al,Zn)49 phases. The phase transition temperature of Mg-25Al-15Zn and Mg-25Al-15Zn-8Cu alloys ​​are 412.1 °C and 405.9 °C respectively; and phase change latent heat values of that were 175.4 J/g and 209.3 J/g. The addition of Cu led to the formation of new phase, reducing the phase transition temperature and increasing the value of phase change latent heat.

Large electrostrain near the phase transition temperature of (Bi0.5Na0.5)TiO3–SrTiO3 ferroelectric ceramics

2008 ◽  
Vol 92 (26) ◽  
pp. 262904 ◽  
Author(s):  
Yuji Hiruma ◽  
Yoshitaka Imai ◽  
Yoshinori Watanabe ◽  
Hajime Nagata ◽  
Tadashi Takenaka
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Ferroelectric Ceramics

scholarly journals Physical studies on phosphonium phosphatidylcholine. A unique [31P]phosphorus nuclear-magnetic-resonance probe for model and biological membranes

1975 ◽  
Vol 151 (3) ◽  
pp. 555-560 ◽  
Author(s):  
E Sim ◽  
P R Cullis ◽  
R E Richards
Keyword(s):  
Phase Transition ◽  
Nuclear Magnetic Resonance ◽  
Transition Temperature ◽  
Magnetic Resonance ◽  
Temperature Dependence ◽  
Phase Transition Temperature ◽  
Shift Reagent ◽  
Scanning Calorimetry ◽  
Distearoyl Phosphatidylcholine ◽  
Nuclear Magnetic

1. Distearoyl phosphatidylcholine and the phosphonium analogue, in which the nitrogen atom is replaced by phosphorus, show similar gel-liquid crystalline transition temperatures as detected by differential scanning calorimetry. 2. The temperature-dependence of the 31P n.m.r. (nuclear-magnetic-resonance) linewidths of the phosphate resonances of sonicated vesicles of distearoyl phosphatidylcholine and the phosphonium analogue are similar. Below the phase-transition temperature the linewidths decrease as the temperature is raised. Above the phase-transition temperature the phosphate resonances are relatively temperature-independent. The phosphonium 31P n.m.r. signal exhibits the same pattern of temperature-dependence. 3. The 31P n.m.r. phosphonium resonance is sensitive to the paramagnetic shift reagent, K3Fe(CN)6. Use of K3Fe(CN)6, together with Nd(NO3)3, enabled the determination of the trans-bilayer distribution of egg-yolk phosphatidylcholine and its phosphonium analogue in co-sonicated vesicles. Both are distributed comparably across the bilayer of the vesicles. 4. The phosphonium 31P n.m.r. signal is much sharper than the corresponding phosphate resonance in both sonicated and unsonicated dispersions of the phosphatidylcholine analogue. 5. The properties of the phosphonium analogue of phosphatidylcholine are discussed in terms of its suitability as a probe of membrane structure.

Effect of HPC on the Thermo-Sensitive and Hydrophilicity of PAN Films

2011 ◽  
Vol 287-290 ◽  
pp. 2793-2796
Author(s):  
Guo Li Gong ◽  
Hui Li
Keyword(s):  
Phase Transition ◽  
Contact Angle ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Scanning Calorimetry ◽  
Blend Films ◽  
Surface Image ◽  
Sensitive Property

In this paper, a series of blending films were prepared based on Polyacrylonitrile (PAN) and hydroxypropylcellulose (HPC). The phase transition temperature of these blend films was investigated by warming UV-vis spectrophotometer and Differential Thermal Scanning Calorimetry (DSC). The results showed that the phase transition temperature of HPC/PAN blend films was lower than that of HPC when adding PAN into HPC and the more PAN contents the lower LCST of blend films. The contact angle and surface image of HPC/APN blend films were studied. It was indicated that HPC could endow PAN film with not only thermo-sensitive property but also great hydrophilicity.

The structure of membranes and membrane proteins embedded in amorphous ice

1992 ◽  
Vol 50 (1) ◽  
pp. 432-433
Author(s):  
Uwe Lücken ◽  
Joachim Jäger
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Membrane Proteins ◽  
Phase Transition Temperature ◽  
Lipid Vesicles ◽  
Freezing Stress ◽  
Amorphous Ice ◽  
Different Temperatures ◽  
Band Pass ◽  
Lipid Polymorphism

TEM imaging of frozen-hydrated lipid vesicles has been done by several groups Thermotrophic and lyotrophic polymorphism has been reported. By using image processing, computer simulation and tilt experiments, we tried to learn about the influence of freezing-stress and defocus artifacts on the lipid polymorphism and fine structure of the bilayer profile. We show integrated membrane proteins do modulate the bilayer structure and the morphology of the vesicles.Phase transitions of DMPC vesicles were visualized after freezing under equilibrium conditions at different temperatures in a controlled-environment vitrification system. Below the main phase transition temperature of 24°C (Fig. 1), vesicles show a facetted appearance due to the quasicrystalline areas. A gradual increase in temperature leads to melting processes with different morphology in the bilayer profile. Far above the phase transition temperature the bilayer profile is still present. In the band-pass-filtered images (Fig. 2) no significant change in the width of the bilayer profile is visible.

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