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A method that allows the investigation of discharge transport mechanism in dielectric films used in MEMS capacitive switches or MIM capacitors or even bare dielectric films is presented. The method is based on monitoring the dielectric film surface or MIM top electrode potential decay rate and the dependence of conductivity on surface potential. The method has been applied in MEMS and MIMs with simultaneously deposited dielectric film to confirm the closeness of transport data in MIM and MEMS devices. The impact of non-uniform charging on local discharge rate and different dielectric film stoichiometry has been also assessed. Finally, the effect of surface leakage due to environment humidity has been also investigated. [2019-0159]

Background/Aim: To characterize global microRNA (miRNA) expression profile in the first trimester maternal plasma of women who subsequently develop late-onset preeclampsia (LOPE) compared to uncomplicated pregnancies. Materials and Methods: Five first trimester plasma samples from women who developed LOPE and 5 controls were analyzed using next generation sequencing technology (NGS) followed by target prediction, Gene Ontology analysis and pathway identification. Quantitative real-time polymerase chain reaction (qRT-PCR) was performed for confirmation in an independent cohort of 12 LOPE cases and 12 controls. Results: miR-23b-5p and miR-99b-5p were down-regulated by >1.5 fold in LOPE complicated pregnancies (p value

Here, we use a simple and effective method to accomplish energy level alignment and thus electron injection barrier control in organic light emitting diodes (OLEDs) with a conventional architecture based on a green emissive copolymer. In particular, a series of functionalized zinc porphyrin compounds bearing π-delocalized triazine electron withdrawing spacers for efficient intramolecular electron transfer and different terminal groups such as glycine moieties in their peripheral substitutes are employed as thin interlayers at the emissive layer/Al (cathode) interface to realize efficient electron injection/transport. The effects of spatial (i.e., assembly) configuration, molecular dipole moment and type of peripheral group termination on the optical properties and energy level tuning are investigated by steady-state and time-resolved photoluminescence spectroscopy in F8BT/porphyrin films, by photovoltage measurements in OLED devices and by surface work function measurements in Al electrodes modified with the functionalized zinc porphyrins. The performance of OLEDs is significantly improved upon using the functionalized porphyrin interlayers with the recorded luminance of the devices to reach values 1 order of magnitude higher than that of the reference diode without any electron injection/transport interlayer.

In the present work, we effectively modify the TiO2 electron transport layer of organic solar cells with an inverted architecture using appropriately engineered porphyrin molecules. The results show that the optimized porphyrin modifier bearing two carboxylic acids as the anchoring groups and a triazine electron-withdrawing spacer significantly reduces the work function of TiO2, thereby reducing the electron extraction barrier. Moreover, the lower surface energy of the porphyrin-modified substrate results in better physical compatibility between the latter and the photoactive blend. Upon employing porphyrin-modified TiO2 electron transport layers in PTB7:PC71BM-based organic solar cells we obtained an improved average power conversion efficiency up to 8.73%. Importantly, porphyrin modification significantly increased the lifetime of the devices, which retained 80% of their initial efficiency after 500 h of storage in the dark. Because of its simplicity and efficacy, this approach should give tantalizing g...

Objective To report the incidence of preterm pre-eclampsia (PE) in women who are screen positive according to the criteria of the National Institute for Health and Care Excellence (NICE) and the American College of Obstetricians and Gynecologists (ACOG), and compare the incidence with that in those who are screen positive or screen negative by The Fetal Medicine Foundation (FMF) algorithm. Methods This was a secondary analysis of data from the ASPRE study. The study population consisted of women with singleton pregnancy who underwent prospective screening for preterm PE by means of the FMF algorithm, which combines maternal factors and biomarkers at 11-13 weeks' gestation. The incidence of preterm PE in women fulfilling the NICE and ACOG criteria was estimated; in these patients the incidence of preterm PE was then calculated in those who were screen negative relative to those who were screen positive by the FMF algorithm. Results A total of 34 573 women with singleton pregnancy delivering at ≥ 24 weeks' gestation underwent prospective screening for preterm PE, of which 239 (0.7%) cases developed preterm PE. At least one of the ACOG criteria was fulfilled in 22 287 (64.5%) pregnancies and the incidence of preterm PE was 0.97% (95% CI, 0.85-1.11%); in the subgroup that was screen positive by the FMF algorithm the incidence of preterm PE was 4.80% (95% CI, 4.14-5.55%), and in those that were screen negative it was 0.25% (95% CI, 0.18-0.33%), with a relative incidence in FMF screen negative to FMF screen positive of 0.051 (95% CI, 0.037-0.071). In 1392 (4.0%) pregnancies, at least one of the NICE high-risk criteria was fulfilled, and in this group the incidence of preterm PE was 5.17% (95% CI, 4.13-6.46%); in the subgroups of screen positive and screen negative by the FMF algorithm, the incidence of preterm PE was 8.71% (95% CI, 6.93-10.89%) and 0.65% (95% CI, 0.25-1.67%), respectively, and the relative incidence was 0.075 (95% CI, 0.028-0.205). In 2360 (6.8%) pregnancies fulfilling at least two of the NICE moderate-risk criteria, the incidence of preterm PE was 1.74% (95% CI, 1.28-2.35%); in the subgroups of screen positive and screen negative by the FMF algorithm the incidence was 4.91% (95% CI, 3.54-6.79%) and 0.42% (95% CI, 0.20-0.86%), respectively, and the relative incidence was 0.085 (95% CI, 0.038-0.192). Conclusion In women who are screen positive for preterm PE by the ACOG or NICE criteria but screen negative by the FMF algorithm, the risk of preterm PE is reduced to within or below background levels. The results provide further evidence to support the personalized risk-based screening method that combines maternal factors and biomarkers. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Pregnant women are at an increased risk of mortality and morbidity owing to COVID-19. Many studies have reported on the association of COVID-19 with pregnancy-specific adverse outcomes, but prediction models utilizing large cohorts of pregnant women are still lacking for estimating the risk of maternal morbidity and other adverse events.The main aim of this study was to develop a prediction model to quantify the risk of progression to critical COVID-19 and intensive care unit admission in pregnant women with symptomatic infection.This was a multicenter retrospective cohort study including 8 hospitals from 4 countries (the United Kingdom, Austria, Greece, and Turkey). The data extraction was from February 2020 until May 2021. Included were consecutive pregnant and early postpartum women (within 10 days of birth); reverse transcriptase polymerase chain reaction confirmed SARS-CoV-2 infection. The primary outcome was progression to critical illness requiring intensive care. The secondary outcomes included maternal death, preeclampsia, and stillbirth. The association between the primary outcome and 12 candidate predictors having a known association with severe COVID-19 in pregnancy was analyzed with log-binomial mixed-effects regression and reported as adjusted risk ratios. All the potential predictors were evaluated in 1 model and only the baseline factors in another. The predictive accuracy was assessed by the area under the receiver operating characteristic curves.Of the 793 pregnant women who were positive for SARS-CoV-2 and were symptomatic, 44 (5.5%) were admitted to intensive care, of whom 10 died (1.3%). The 'mini-COvid Maternal Intensive Therapy' model included the following demographic and clinical variables available at disease onset: maternal age (adjusted risk ratio, 1.45; 95% confidence interval, 1.07-1.95; P=.015); body mass index (adjusted risk ratio, 1.34; 95% confidence interval, 1.06-1.66; P=.010); and diagnosis in the third trimester of pregnancy (adjusted risk ratio, 3.64; 95% confidence interval, 1.78-8.46; P=.001). The optimism-adjusted area under the receiver operating characteristic curve was 0.73. The 'full-COvid Maternal Intensive Therapy' model included body mass index (adjusted risk ratio, 1.39; 95% confidence interval, 1.07-1.95; P=.015), lower respiratory symptoms (adjusted risk ratio, 5.11; 95% confidence interval, 1.81-21.4; P=.007), neutrophil to lymphocyte ratio (adjusted risk ratio, 1.62; 95% confidence interval, 1.36-1.89; P.001); and serum C-reactive protein (adjusted risk ratio, 1.30; 95% confidence interval, 1.15-1.44; P.001), with an optimism-adjusted area under the receiver operating characteristic curve of 0.85. Neither model showed signs of a poor fit. Categorization as high-risk by either model was associated with a shorter diagnosis to intensive care unit admission interval (log-rank test P.001, both), higher maternal death (5.2% vs 0.2%; P.001), and preeclampsia (5.7% vs 1.0%; P.001). A spreadsheet calculator is available for risk estimation.At presentation with symptomatic COVID-19, pregnant and recently postpartum women can be stratified into high- and low-risk for progression to critical disease, even where resources are limited. This can support the nature and place of care. These models also highlight the independent risk for severe disease associated with obesity and should further emphasize that even in the absence of other comorbidities, vaccination is particularly important for these women. Finally, the model also provides useful information for policy makers when prioritizing national vaccination programs to quickly protect those at the highest risk of critical and fatal COVID-19.

The present paper provides a novel, inexpensive and non-destructive method to assess the surface charge density variance in capacitive RF-MEMS switches. The charge variance evolution can be monitored during charging and discharging processes by measuring the up-state capacitance, in addition to the mean value, providing results directly related to charging failure mechanisms and the prediction of the devices lifetime for unipolar/bipolar actuation. Also, the experimental results can be used to engineer the dielectric film electrical properties in order to control the surface and bulk conductivities according to needed application.

This paper presents a systematic investigation of the effect of stressing bias polarity to the discharge process of plasma enhanced chemical vapor deposition SiN films that have been fabricated under different deposition conditions. Dielectric charging asymmetry has been observed on the utilized films of metal-insulator-metal capacitors and microelectromechanical systems capacitive switches, since charging is enhanced when negative polarization bias is applied to the top electrode. In addition, it is shown that deposition conditions play a key issue role on the degree of this asymmetry. Finally, a physical model which assumes that hopping dominates the discharging process is used in order to gain a better understanding of the processes that are responsible for the appearance of asymmetric dielectric charging and the results correlate with the material’s electrical properties.

This work presents an investigation of the electrical behavior of below percolation threshold CNTs-filled PDMS nanocomposites. Fabricated films were assessed with the aid of current-voltage characteristic and charging/discharging current transient method. The obtained results revealed the presence of a non-negligible hysteresis and the electrical conduction is found to be dominated by internal field emission processes. Finally, the role of change of direction of the applied voltage on the conduction processes has been investigated for the first time. Display Omitted Electrical properties of PDMS/MWCNTs nanocomposites were studied.Results revealed the presence of a non-negligible hysteresis in I-V characteristics.Nanocomposites exhibit asymmetrical counterclockwise hysteresis in I-V curves.Electrical behavior during voltage ascending differs from the one during descending.Low field conductivity increases after each I-V loop measurement.

The paper presents a new method to determine and monitor the surface charge density of dielectric film in capacitive MEMS switches which experience a significant interference from substrate parasitic MOS capacitors coupling. The method is based on the analysis of composite MEMS device and bridge-less back-to-back substrate MOS capacitors. The difference of the derivatives of the two device C-V characteristics allows the calculation of dielectric film charge density. The method has been applied to monitor the charging build-up during device stress. Display Omitted Dielectric charging is assessed in MEMS switches with substrate interference.A new method is proposed to investigate dielectric charging.Assessment separates the contribution of the substrate network.The method has been applied to monitor the charging build-up during device stress.

The field emission and resulting breakdown induced damage in the actuation paths of MEMS capacitive switches are investigated. The effect of asperities burning due to Joule heating and the resulting explosive break down are presented. The breakdown gives rise to almost mirror craters formation on the cathode and anode electrodes. A linear relation between crater diameter and the breakdown current is found when breakdown occurs in vacuum. In ambient atmosphere the breakdown leads to large amplitude current oscillations and the formation of extended damage on both electrodes.

A more realistic approach of the discharging process in MEMS capacitive switches is presented with the introduction of the effective temperature in order to determine the behavior of the microscopic parameters of hopping conduction, which dominates the process. The use of Kelvin Probe method in MIM capacitors that simulates the discharging process in MEMS switches during up-state revealed that both the increase of temperature and stressing field intensity results the decrease of mean hopping length. This result arises from the simultaneous contribution of the transport energy levels associated with the impact of the stressing field and temperature. Also, a correlation was found experimentally between the stretched exponential decay and the hopping process. The proposed method was also applied in MEMS switches where a similar behavior of the hopping parameters was found, providing evidence that the control of the hopping length to an optimum value can provide fast discharging and low leakage currents, increasing the device lifetime.

This work presents an in depth investigation regarding the effect of PECVD silicon nitride (SiNx) stoichiometry on its charging mechanisms. The investigation took place in SiNx dielectric films with different Si-content (x = 0.47–1.04) with the aid of Metal-Insulator-Metal capacitors. The experimental assessment involved a single-point Kelvin probe System, the monitoring of Current – Voltage characteristics and the employment of Thermally Stimulated Depolarization Currents technique. The results indicate that when Si-content increases the injected charge distribution is expected to extend deeper in the dielectric films and charges are displaced faster through the bulk material and towards the bottom electrode. The effective temperature is used in order to investigate hopping conduction that dominates charge transport in the bulk material and thus a more realistic approach of the discharging process is presented. Finally, the increase of Si-content seems to introduce defect states in SiNx, which are probably associated to Si-dangling bonds, and the presence of discrete depolarization mechanisms are investigated, the characteristics of which are analytically described taking into consideration the effect of stoichiometry. These results that can be useful in material engineering in order to improve the lifetime of RF MEMS capacitive switches.

Metal-insulator-metal (MIM) capacitors with single TiO2 and a TiO2/Y2O3 stack are used as insulator films in MIM and MEMS, respectively, are explored. It is found that, under electron injection from bottom electrode, the TiO2 MIM capacitors demonstrate resistive switching with a magnitude of leakage currents not usable for MEMS application. The deposition of a stacked TiO2/Y2O3 dielectric film improves the MEMS performance without compromising the low dielectric charging of TiO2 single layer.