Screening for pre-eclampsia by maternal factors and biomarkers at 11-13 weeks' gestation

Objective: To examine the performance of screening for early-, preterm- and term-preeclampsia (PE) at 11 13 weeks’ gestation by maternal factors and combinations of mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI), serum placental growth factor (PLGF) and serum pregnancy associated plasma protein A (PAPP A). Methods The data for this study were derived from three previously reported prospective non intervention screening studies at 11+0 – 13+6 weeks’ gestation in a combined total of 61,174 singleton pregnancies, including 1,770 (2.9%) that developed PE. Bayes theorem was used to combine the prior distribution of the gestational age at delivery with PE, obtained from maternal characteristics, with various combinations of biomarker multiple of the median (MoM) values to derive the p patient specific risks of delivery with PE at <37 weeks’ gestation. The performance of such screening was estimated. Results In pregnancies that develop ed PE , compared to those without PE, the MoM values of UtA-PI and MAP were increased and PAPP A and PLGF were decreased and the deviation from normal was greater for early than late PE for all four biomarkers. Combined screening by maternal factors, UtA-PI, MAP and PLGF predicted 90% of early PE, 75% of preterm PE and 4 1 % of term PE, at screen positive rate of 10%; inclusion of PAPP A did not improve the performance of screening The performance of screening depended on the racial origin of the women; in screening by a combination of maternal factors, MAP, UtA-PI and PLGF and use of the risk cut off of 1 in 10 0 for PE at <37 weeks in Caucasian women, the screen positive rate was 10% and detection rates for early --, preterm and term PE were 88%, 69% and 40%, respectively. With the same method of screening and risk cut off in women of Afro Caribbean racial origin, the screen positive rate was 34% and detection rates for early --, preterm and term PE were 100%, 92% and 75%, respectively. Conclusion Screening by maternal factors and biomarkers at 11-13 weeks’ gestation can identify a high proportion of pregnancies that develop early- and preterm-PE

Dielectric relaxation of β-cyclodextrin-polyiodide complexes (β-cyclodextrin)2·LiI7 · 8H 2O and (β-cyclodextrin)2 · KI7 · 8H2O

The frequency and temperature dependence of real (ε′) and imaginary (ε″) parts of the dielectric constant of polycrystalline complexes (β-CD)2 ·LiI7 · 8H 2O and (β-CD)2 · KI7 · 8H2O (β-CD = β-cyclodextrin) have been investigated over the frequency and temperature ranges of 0-100 kHz and 120-300 K. The temperature dependence of ε′, ε′ and phase shift φ showing two steps, two peaks and two minima respectively, reveals the existence of two kinds of water molecule, the tightly bound and the easily movable water molecules, in both complexes. The first peak of φ″(T) or the first minimum of ′(T) present the transformation of flip-flop hydrogen bonds to the normal state. The second ε″(T) peak or φ(T) minimum correspond to the easily movable water molecules or to a partial transformation of tightly bound to easily movable water molecules. Both samples for T &amp;gt; 275 K show semiconductive behaviour with energy gaps 0.72 eV for the (β-CD) 2 · LiI7 · 8H2and 0.58 eV for the (β-CD)2 · KI7 · 8H2O complex. The conductivity at temperatures T&amp;gt;220K is greater for the Li complex and at T&amp;lt;220K both complexes have similar conductivity values The relaxation time varies in a A-like curve (from 180 K to 260 K) and rises rapidly for temperatures greater than 260 K, indicating the process of ionic movements. The activation energies around the transition temperature 0.40-0.50k BTtrans for the (β-CD)2 · LiI 7 · 8H2O and 0.78-1.00kBT trans for the (β-CD)2 · KI7 · 8H2O reveal the greater stability of the β-K complex against that of the β-Li complex

A comparative dielectric spectroscopy investigation of beta-cyclodextrin polymer and carboxymethyl beta-cyclodextrin polymer cross-linked by epichlorohydrin

The β-cyclodextrin polymer (β-CDP) and the carboxymethyl-β-cyclodextrin polymer (CM-β-CDP) cross-linked by epichlorohydrin were investigated by dielectric spectroscopy over the frequency range 0.1–100 kHz in the temperature ranges 132.6–464.8 K and 132.9–500.9 K, respectively. The β-CDP reveals a reversible order-disorder transformation of some normal hydrogen bonds to flip-flop type at T trans = 220.1 K, whereas the CM-β-CDP doesn&apos;t show any transformation of hydrogen bonds. The ac-conductivity plot of β-CDP (lnσ vs 1/T) shows a linear part obeying the Arrhenius equation in the range 289.8–268.8 K with E α = 0.71 eV during cooling and 0.77 eV during heating. A deformed bell-shaped curve with maximum values at T trans = 222.7 K during cooling and 223.8 K during heating in the range 132.6–268.8 K, is due to the hydrogen-bonded transformation. At 328.9 &amp;lt; T &amp;lt; 407 K the ac-conductivity presents a bell-shaped curve with maximum value located at 363.1 K, revealing a new order-disorder transformation. The breaking and the restoration of more stable hydrogen bonds are confirmed by the temperature variation of relaxation time, as three successive topical maxima with values 8.9 μs (223.8 K), 8.9 μs (307.6 K) and 11.9 μs (369.7 K). Above 407.0 K, lnσ increases linearly according to Arrhenius law with E α = 0.26 eV because of the newly-formed hydrogen-bonded chains. In the case of CM-β-CDP the lnσ vs 1/T plot reveals two linear regions where the Arrhenius equation is valid. Τhe first in the range 252.3–288.2 K (E α = 0.28 eV cooling or Ε α = 0.33 eV heating) is due to the protons originated from the β-CD hydroxyl groups and water molecules while the second in the range 316–349 K (E α = 0.78 eV heating) is due to the carboxymethyl moieties dissociation. The relaxation time τ of CM-β-CDP increases from 7.5 μs (132.9 K) to 9.5 μs (285.4 K) and then rapidly reaches the value 11.8 μs at 293.7 K denoting the no breaking of hydrogen bonds. Cole-Cole plots of both samples are presented at selective temperatures. © 2019 Elsevier B.V

Dielectric behavior of gamma-cyclodextrin polymer and carboxymethyl gamma-cyclodextrin polymer cross-linked both by epichlorohydrin

The γ-cyclodextrin polymer (γ-CDP) and carboxymethyl-γ-cyclodextrin polymer (CM-γ-CDP) cross-linked both by epichlorohydrin were investigated via dielectric spectroscopy over the frequency range 0.1–100 kHz and the temperature ranges 122.0–472.4 K and 123.6–460.3 K, respectively. The γ-CDP reveals a thermally reversible transformation of some normal hydrogen bonds to flip-flop type at Ttrans = 199.1 K, whereas the CM-γ-CDP doesn&apos;t show any transformation of hydrogen bonds. Both systems present in the lnσ vs 1/T plot two linear parts following the Arrhenius equation. In the case of γ-CDP, the first linear part during cooling (a) has activation energy Eα = 0.41 eV and during heating (b) has Eα = 0.42 eV in the range 259.7–310.0 K. The second linear part (c) in the range 316.5–357.1 K has Eα = 0.36 eV. The corresponding values of CM-γ-CDP are Eα = 0.32 eV (a), Eα = 0.33 eV (b) in the range 242.1–295.1 K and Eα = 0.91 eV (c) in the range 307–366.1 K. The linear parts (a) and (b) of both polymers are related to the accumulation of protons in the grain-boundary regions as it is depicted in the Cole-Cole plots. The linear part (c) is related to the proton migration from the grain-boundary region to the electrodes and the dehydration process taking place. The ac-conductivity of CM-γ-CDP is considerably higher than that of γ-CDP as the partial hydrogen replacement of some hydroxyl groups by carboxymethyl moiety, renders numerous protons more flexible to move along the hydrogen-bonded network, contributing to the conductivity. Both systems after the dehydration process, presented a newly-formed hydrogen bonded network due to the reorientation of hydrogen bonded chains at T &amp;gt; 397.0 K for γ-CDP and T &amp;gt; 420.9 K for CM-γ-CDP. © 2020 Elsevier B.V

Correlation of dielectric properties, Raman spectra and calorimetric measurements of β-cyclodextrin-polyiodide complexes (β-cyclodextrin) 2·BaI7·11H2O and (β-cyclodextrin)2· CdI7·15H 2O

The frequency and temperature dependence of real and imaginary parts of the dielectric constant (ε′, ε″), the phase shift (φ) and the ac-conductivity (σ) of polycrystalline complexes (β-CD) 2·BaI7-11H2O and (β-CD) 2·CdI7·15H2O (β-CD = β-cyclodextrin) has been investigated over the frequency and temperature ranges 0-100kHz and 140-420 K in combination with their Raman spectra, DSC traces and XRD patterns. The ε′(T), ε″(T) and φ(T) values at frequency 300 Hz in the range T &amp;lt; 330 K show two sigmoids, two bell-shaped curves and two minima respectively revealing the existence of two kinds of water molecule, the tightly bound and the easily movable. Both complexes show the transition of normal hydrogen bonds to flip-flop type at 201 K. In the β-Ba complex most of the eleven water molecules remain tightly bound and only a small number of them are easily movable. On the contrary, in the β-Cd case the tightly bound water molecules are transformed gradually to easily movable. Their DSC traces show endothermic peaks with onset temperatures 118°C, 128°C for β-Ba and 106°C, 123°C, 131°C for β-Cd. The peaks 118°C, 106°C, 123°C are related to the easily movable and the tightly bound water molecules, while the peaks at 128°C, 131°C are caused by the sublimation of iodine. The activation energy of Ba2+ ions is 0.52eV when all the water molecules exist in the sample and 0.99eV when the easily movable water molecules have been removed. In the case of β-Cd the corresponding activation energies are 0.57eV and 0.33eV. The Raman peaks at 179cm-1, 170cm-1 and 165-166cm-1 are due to the charge transfer interactions in the polyiodide chains. © 2005 Taylor &amp;amp; Francis Group Ltd

Dielectric relaxation of α-cyclodextrin-polyiodide complexes (α-cyclodextrin)2 · LiI3 · I2 · 8H2O and (α-cyclodextrin)2 · Cd0.5 · I5 · 26H2O

The frequency and temperature dependence of real and imaginary parts of the polycrystalline complexes was discussed. The transition temperature was indicated by a peak in the imaginary part of the dielectric constant and by a minimum in the phase shift component. Results for both samples η′ and η″ showed thermal hysteresis during a cooling-heating cycle, for all frequencies examined

Dipole relaxation and proton transport in polycrystalline γ-cyclodextrin hydrate: A dielectric spectroscopy study

The polycrystalline γ-cyclodextrin hydrate (γ-CD•12. 2H2O) has been investigated via dielectric spectroscopy over a frequency range of 0-100 kHz and the temperature ranges of 108.0-298.5 K (cooling) and 109.0-433.0 K (heating). At T &amp;lt; 250.0 K, the electrical properties of the sample accept a great contribution from the flip-flop proton orientational disorder and a much lesser one from the positional fluctuations of the water molecules. Moreover, a strong synergy is observed between the stability of the γ-CD molecules and the dynamic disorder of the infinite flip-flop chains. This type of disorder disappears upon cooling (T trans = 186.7 K) and reappears upon heating (Ttrans = 194.5 K). At T &amp;gt; 250.0 K, the dielectric permittivity ε′ and loss ε″ increase abruptly due to the proton dc-conductance of γ-CD•12.2H2O which has been interpreted in terms of a theoretical model (Pnevmatikos, 1988) being consistent with the generation of ionic defects and their combination with the dipole reorientations in a collective motion of soliton-type. The influence of the simultaneous dehydration process on this charge transport mechanism relies on the very sensitive balance between the diffusive motion of water molecules (exchange between symmetry related positions) and their removal from the crystal lattice. The Arrhenius semiconductive behavior of the ac-conductivity in the ranges of 257.1-313.2 K (Ea = 0.42 eV) and 331.2-385.1 K (Ea = 0.39 eV) implies the dominance of water diffusion which conserves the structural integrity of the endless hydrogen-bonded chains and the proton transfer along them. The limited decrease of the ac-conductivity from 313.2 to 331.2 K along with its rapid decrease above 385.1 K, indicates that the removal of the water molecules rules out their diffusive motion. The Cole-Cole diagrams (ε″ vs. ε′) make clear that during the heating process the grain boundary polarization gradually becomes more significant than the grain interior one. In the range of 348.0-385.1 K, the constrictive grain boundary resistances are totally eliminated allowing the extensive proton transport through the grains of the polycrystalline specimen. © 2011 Published by Elsevier B.V

High density flip-flop hydrogen-bonding networks in the β-cyclodextrin heptaiodide inclusion complexes with Bi3+ and Te4+ ions. Combined dielectric relaxation, Raman scattering and thermal analysis

The polycrystalline inclusion complexes (β-CD)2·TeI7·17H2O and (β-CD)2·BiI7·17H2O have been investigated via dielectric spectroscopy over a frequency range of 0-100 kHz and the temperature range of 140-425 K. Furthermore, a DSC study was carried out in the range of 273-423 K, whereas the Raman spectra (303-393 K) of β-Te were compared to the previously examined ones of β-Bi. In the case of β-Te an important percentage of normal H-bonds is transformed into flip-flop ones (Ttrans = 216.8 K) as it comes out by the corresponding ε′ (T), ε″ (T) and φ(T) variations at T &amp;lt; 250 K (Δε′ = 18.6, ε″max = 4.8, φmin = 69.9°). In β-Bi the greatest percentage of normal H-bonds is transformed into those of the flip-flop type (Ttrans = 223.6 K, Δε′ = 49.6, ε″max = 16, φmin = 58.6ο) producing a disordered H-bonding network of a much higher density than that of β-Te. At T &amp;gt; 250 K, the ac-conductivity (lnσ vs. 1 / T) of these systems follows an Arrhenius behaviour with activation energies 0.54 and 0.46 eV for β-Te and 0.38, 0.68 and 0.58 eV for β-Bi. This exponential increment reflects the combined contributions of the water network, the oscillating cations and the dehydration process. The abrupt increase of the ac-conductivity at T &amp;gt; 398.5 K is caused by the sublimation of iodine. The temperature-dependent Raman spectra of β-Te exhibit the band shift of 178 → 172 cm- 1 which is identical to that of β-Bi, implying a similar elongation of their I2 units. The high density flip-flop hydrogen-bonding network in the latter complex seems to play a key role in limiting the Lewis base character of I-3. © 2008 Elsevier B.V. All rights reserved

Impedance spectroscopy study of nickel electrodeposits

Nickel electrodeposits prepared in NiSO4 and NiCl2 electrolytes with thicknesses of 43-49.4 μm were examined by the impedance spectroscopy (IS) method for a-c frequencies 1 Hz-100 kHz. The Nyquist diagrams were single, almost perfect semicircles, suggesting the applicability of the in parallel combination of the Ra-Ca elements characterised by a single relaxation time, 8.27 × 10-6 s, combined in series with another Rb element, Rb ≪ Ra. This relaxation time predicted that the incorporated hydrogen atoms are involved in the process of conduction by a hopping/diffusion mechanism, which is differentiated in the cases of NiSO4-Ni and NiCl2-Ni deposits. The diffusion coefficient of hydrogen, 1.25 × 10-11 cm2 s-1, was determined. The microstructure of Ni electrodeposits was also studied and characterised by electron microscopy. Finally, a general model for the microstructure of Ni electrodeposits, consistent with the results of impedance spectroscopy, was formulated. © 2002 Elsevier Science B.V. All rights reserved