scholarly journals Methods to determine the pressure dependence of the molecular order parameter in (bio)macromolecular fibres

Soft Matter ◽  
2015 ◽  
Vol 11 (6) ◽  
pp. 1158-1164 ◽  
Author(s):  
Arthur Markus Anton ◽  
Christof Gutsche ◽  
Wilhelm Kossack ◽  
Friedrich Kremer
Keyword(s):  
Ftir Spectroscopy ◽  
Optical Microscopy ◽  
Pressure Dependence ◽  
Order Parameter ◽  
Pressure Effects ◽  
Molecular Order ◽  
Macroscopic Orientation

Combining FTIR spectroscopy and optical microscopy enables to correct the measured dichroism for the fibres' macroscopic orientation, and hence, separating pressure effects on macroscopic and microscopic scales.

scholarly journals Comparative Study of Roman Iron Slags Discovered in the Roman Auxiliary Fort and Settlement of Călugăreni

2018 ◽  
Vol 1 (2) ◽  
pp. 65-72 ◽  
Author(s):  
Enikő Bitay ◽  
Irén Kacsó ◽  
Szilamér Péter Pánczél ◽  
Erzsébet Veress
Keyword(s):  
Comparative Study ◽  
Ftir Spectroscopy ◽  
Optical Microscopy ◽  
Mineralogical Composition ◽  
Iron Slag ◽  
Eastern Border ◽  
The Military ◽  
Archaeological Excavations

Abstract Iron slag samples unearthed at the eastern border of Roman Dacia, in the auxiliary fort and the military settlement of Călugăreni (Mikháza) are investigated by macroscopic inspection, optical microscopy (OM) and FTIR spectroscopy in order to comparatively characterize their macro- and microstructure as well as their mineralogical composition. During the recent archaeological excavations, a large number of iron artefacts were discovered together with a great quantity of iron slag fragments. The present paper focuses on the data obtained from 17 slag samples.

scholarly journals Phospholipase C activation by ethanol in rat hepatocytes is unaffected by chronic ethanol feeding

1990 ◽  
Vol 272 (1) ◽  
pp. 59-64 ◽  
Author(s):  
J B Hoek ◽  
T F Taraschi ◽  
K Higashi ◽  
E Rubin ◽  
A P Thomas
Keyword(s):  
Phospholipase C ◽  
Order Parameter ◽  
Plasma Membranes ◽  
Structural Changes ◽  
Rat Hepatocytes ◽  
Maximal Response ◽  
Molecular Order ◽  
Transient Activation ◽  
Ethanol Feeding

The activation of phosphoinositide-specific phospholipase C by ethanol was compared in hepatocytes isolated from ethanol-fed rats and from pair-fed control animals. Ethanol (100-300 mM) caused a dose-dependent transient increase in cytosolic free Ca2+ levels in indo-1-loaded hepatocytes from both groups of animals. The rate of Ca2+ increase was similar in hepatocytes from control and ethanol-fed rats, but the decay of the Ca2+ increase was somewhat slower in the latter preparation. The ethanol-induced Ca2+ increase caused activation of glycogen phosphorylase, with 50% response at 50 mM-ethanol and a maximal response at 150-200 mM-ethanol, not significantly different in hepatocytes from control and ethanol-fed animals. Ins(1,4,5)P3 formation in response to ethanol (300 mM) or vasopressin (2 nM or 40 nM) was also similar in the two preparations. It is concluded that long-term ethanol feeding does not lead to an adaptive response with respect to the ethanol-induced phospholipase C activation in rat hepatocytes. The ability of ethanol in vitro to decrease membrane molecular order in liver plasma membranes from ethanol-fed and control rats was measured by e.s.r. Membranes from ethanol-fed animals had a significantly lower baseline order parameter compared with control preparations (0.313 and 0.327 respectively), indicative of decreased membrane molecular order. Addition of 100 mM-ethanol significantly decreased the order parameter in control preparations by 2.1%, but had no effect on the order parameter of plasma membranes from ethanol-fed rats, indicating that the plasma membranes had developed tolerance to ethanol, similar to other membranes in the liver. Thus the membrane structural changes associated with this membrane tolerance do not modify the ethanol-induced activation of phospholipase C. The transient activation of phospholipase C by ethanol in hepatocytes may play a role in maintaining an adaptive phenotype in rat liver.

Pressure Dependence of Chlorine NQR in Strontium Chlorate and Barium Chlorate Monohydrate

1986 ◽  
Vol 41 (1-2) ◽  
pp. 338-340 ◽  
Author(s):  
V. Krishnan ◽  
T. V. Krishna Moorthy ◽  
J. Ramakrishna
Keyword(s):  
Electric Field ◽  
Electric Field Gradient ◽  
Field Gradient ◽  
Pressure Dependence ◽  
Pressure Effects ◽  
Volume Dependence ◽  
Torsional Frequency

The pressure dependence of the 35Cl-NQR frequencies in barium chlorate monohydrate and strontium chlorate, has been investigated up to 7000 kg cm-2. Ba(ClO3)2 · H2O shows a single 35Cl-NQR line at 29.337 MHz (T = 297 K, p = 1 bar). ν(35Cl) increases linearly with pressure in the range studied, with (1/ν )(∂ν/∂p)T = + 0.409 x 10-6 kg-1 cm2 which is much smaller than observed in NaClO3 and KCIO3. Sr(ClO3)2 also gave a single 35Cl-NQR frequency at 20.105 MHz (T = 297 K, p = 1 bar). The pressure dependence is very small and negative in this case. The data in both cases have been analysed to obtain the volume dependence of the torsional frequency. It is pointed out that explicit pressure effects on the electric field gradient have to be taken into account to provide an explanation for the observed pressure dependence of ν (35Cl).

Dissociation and reassociation of enzyme-treated caseins under high pressure

1989 ◽  
Vol 56 (3) ◽  
pp. 435-442 ◽  
Author(s):  
Kunio Ohmiya ◽  
Tsutomu Kajino ◽  
Shoichi Shimizu ◽  
Kunihiko Gekko
Keyword(s):  
High Pressure ◽  
Volume Change ◽  
Pressure Dependence ◽  
Critical Pressure ◽  
Pressure Effects ◽  
Pressure Curve ◽  
Immobilized Trypsin

SummaryThe effects of pressure on the association states of enzyme-treated casein molecules were studied by monitoring the turbidity of the solutions under pressures up to 3000 kg/cm2. β-Casein polymers, partly degraded with immobilized trypsin, dissociated with increasing pressure up to a critical pressure (e.g. 1200 kg/cm2) and then reassociated under the higher pressure up to 3000 kg/cm2, following a parabolic turbidity-pressure curve. In the case of chymosin-treated κ-casein, a similar pressure dependence of turbidity was found under the same pressure conditions. Based on these results, the pressure effects on dissociation and reassociation of casein molecules were discussed in terms of the volume change of water around their hydrophobic moieties.

Pressure Effects upon the Rates of Aquation of Halopentaamminechromium(III) Ions: Evidence for an Associative Mechanism

1973 ◽  
Vol 51 (6) ◽  
pp. 821-827 ◽  
Author(s):  
G. Guastalla ◽  
T. W. Swaddle
Keyword(s):  
Transition State ◽  
Molar Volume ◽  
Pressure Dependence ◽  
Ground State ◽  
Pressure Effects ◽  
Water Molecules ◽  
Associative Mechanism

For the replacement of X− by H2O in Cr(NH3)5X2+, ΔVo* (the value of the volume of activation ΔV* at zero pressure) at 25.0° in 0.1 m NH4ClO4 is −10.8, −10.2, and − 9.4 cm3 mol−1 respectively for X− = Cl−, Br−, and I−, while ΔV, the molar volume of reaction, is −8.4, −7.2 and −6.0 cm3 mol−1. The pressure-dependence of ΔV* can be expressed in terms of the number x of water-molecules which are electrostricted as the systems go from ground-state to transition-state; for X− = Cl−, Br−, and I−, x = 1.9, 2.0, and 1.7. These data, combined with ΔV* = −5.8 cm3 mol−1 for the aquo-exchange of Cr(NH3)5OH23+, indicate an associative mechanism for these reactions, as does the contrast with ΔV0* data for the formally analogous, but dissociatively-activated, reactions of Co(NH3)5X(3−n)+.

scholarly journals Pressure Effects on the Optical Properties of NdVO4

Crystals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 237 ◽  
Author(s):  
Enrico Bandiello ◽  
Josu Sánchez-Martín ◽  
Daniel Errandonea ◽  
Marco Bettinelli
Keyword(s):  
Phase Transition ◽  
Optical Properties ◽  
Absorption Band ◽  
Phase Change ◽  
Band Gap ◽  
Pressure Dependence ◽  
Structural Changes ◽  
Pressure Effects ◽  
Absorption Bands ◽  
Fundamental Absorption Band

We report on optical spectroscopic measurements in pure NdVO4 crystals at pressures up to 12 GPa. The influence of pressure on the fundamental absorption band gap and Nd3+ absorption bands has been correlated with structural changes in the crystal. The experiments indicate that a phase transition takes place between 4.7 and 5.4 GPa. We have also determined the pressure dependence of the band-gap and discussed the behavior of the Nd3+ absorption lines under compression. Important changes in the optical properties of NdVO4 occur at the phase transition, which, according to Raman measurements, corresponds to a zircon to monazite phase change. In particular, in these conditions a collapse of the band gap occurs, changing the color of the crystal. The changes are not reversible. The results are analyzed in comparison with those deriving from previous studies on NdVO4 and related vanadates.

scholarly journals Inducing nematic ordering of cellulose nanofibers using osmotic dehydration

Nanoscale ◽  
2018 ◽  
Vol 10 (48) ◽  
pp. 23157-23163 ◽  
Author(s):  
Valentina Guccini ◽  
Shun Yu ◽  
Michael Agthe ◽  
Korneliya Gordeyeva ◽  
Yulia Trushkina ◽  
...  
Keyword(s):  
Optical Microscopy ◽  
Small Angle ◽  
Order Parameter ◽  
Osmotic Dehydration ◽  
Cellulose Nanofibers ◽  
Polarized Optical Microscopy ◽  
X Ray ◽  
Rheological Measurements ◽  
Nematic Ordering ◽  
X Ray Scattering

The formation of nematically-ordered cellulose nanofiber (CNF) suspensions with an order parameter fmax ≈ 0.8 is studied by polarized optical microscopy, small-angle X-ray scattering (SAXS), and rheological measurements as a function of CNF concentration.

Pressure Dependence of the Dielectric Anisotropy of 5CB and 6CB

1995 ◽  
Vol 50 (9) ◽  
pp. 826-830
Author(s):  
Stanislaw Urban
Keyword(s):  
Magnetic Field ◽  
High Pressure ◽  
Magnetic Materials ◽  
Pressure Dependence ◽  
Order Parameter ◽  
Nematic Phase ◽  
Correlation Factor ◽  
Dielectric Anisotropy ◽  
High Pressure Chamber ◽  
Electronic Polarization

Abstract The pressure-dependence of the dielectric anisotropy, Δε = ε0|| - ε0⊥, of two nematogens, n-pentyl-and n-hexyl-cyanobiphenyl (5CB and 6CB) has been measured at constant temperature. For this purpose a high pressure chamber made of non-magnetic materials was constructed, allowing for the orientation of the samples by a magnetic field. The pressure dependencies of ΔεT were analyzed in the frame of the Maier-Meier equations for the principal permittivity components in the nematic phase. It was found that the relation between Δε and the order parameter S is not properly described by these equations. The Kirkwood correlation factor calculated on the basis of the present results and the Maier-Meier equations is smaller than 0.5, whereas it increases to a more realistic value (~0.7) if the electronic polarization is incorporated in the equations.

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