Preparation and Device Applications of Ferroelectric β-PVDF Films

Organic ferroelectric materials have unique characters comparing to their inorganic counterparts in electronics because they show the advantages such as low cost, lightweight, small thermal budget, flexible and nontoxic characteristics. The ferroelectric poly(vinylidene fluoride) (PVDF) is mostly desired for memory devices due to its polar phase. To obtain the ferroelectric memory devices for data storage, ultrathin PVDF films are required to allow for low operation voltages with both small roughness and free of pin-holes. Micron-meter thick films of ferroelectric phase PVDF can be easily achieved by many preparation methods. But the nanofilms could be mainly fabricated by coating method and Langmuir–Blodgett deposition technique. Meanwhile, according to the structure of devices, four types of organic memory cells using ferroelectric phase PVDF films were introduced, such as memory based on metal/organic semiconductor/metal ferroelectric tunnel junctions, organic capacitors, field effect transistor and organic diodes. The research has been mainly done in Zhang’s laboratory from September 2016 to explore the preparation and potential applications of ferroelectric PVDF films. In this chapter, we summarize several device investigations and show the PVDF films have the promising memory applications

Effect of bedtime administration of blood-pressure lowering agents on ambulatory blood pressure monitoring results: A meta-analysis

Background: Bedtime administration of antihypertensive drugs currently receives more at­tention, but no clear consensus has been reached on the blood pressure (BP)-lowering effect of this strategy. Methods: We systematically searched literature for clinical trials of ingestion time of anti­hypertensive drugs evaluated by ambulatory blood pressure monitoring (ABPM) to perform a meta-analysis which aimed at determining the difference in diurnal, nocturnal, and 24-h mean of systolic BP (SBP) and diastolic BP (DBP), absolute BP reduction from baseline between bedtime administration group (experimental group) and morning (awaking) administration group (control group). Results: The synthesis analysis showed that the level of BP in bedtime administration group was lower than the morning administration group, which reduced diurnal SBP/DBP by 1.67/1.13 mm Hg (p = 0.36/0.48), 24-h SBP/DBP by 2.78/0.36 mm Hg (p = 0.09/0.62), nocturnal SBP/DBP by 6.32/3.17 mm Hg (p = 0.03/0.007). Furthermore, there was lack of statistically significant differences in the diurnal mean of SBP/DBP reduction from baseline between the two groups (p = 0.94/0.85), but bedtime administration resulted in significant reduction from baseline in the nocturnal mean of SBP/DBP, by –4.72/–3.57 mm Hg (p = 0.01/0.05). Funnel plot demonstrated that there was no evidence of publication bias. Conclusions: Administration of ≥ 1 antihypertensive drugs at bedtime or evening results in a greater reduction of nocturnal hypertension than dosing in the morning without loss of efficacy of diurnal and 24 h mean BP reduction

The Changing Landscape for Stroke\ua0Prevention in AF: Findings From the GLORIA-AF Registry Phase 2

Background GLORIA-AF (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients with Atrial Fibrillation) is a prospective, global registry program describing antithrombotic treatment patterns in patients with newly diagnosed nonvalvular atrial fibrillation at risk of stroke. Phase 2 began when dabigatran, the first non\u2013vitamin K antagonist oral anticoagulant (NOAC), became available. Objectives This study sought to describe phase 2 baseline data and compare these with the pre-NOAC era collected during phase 1. Methods During phase 2, 15,641 consenting patients were enrolled (November 2011 to December 2014); 15,092 were eligible. This pre-specified cross-sectional analysis describes eligible patients\u2019 baseline characteristics. Atrial fibrillation disease characteristics, medical outcomes, and concomitant diseases and medications were collected. Data were analyzed using descriptive statistics. Results Of the total patients, 45.5% were female; median age was 71 (interquartile range: 64, 78) years. Patients were from Europe (47.1%), North America (22.5%), Asia (20.3%), Latin America (6.0%), and the Middle East/Africa (4.0%). Most had high stroke risk (CHA2DS2-VASc [Congestive heart failure, Hypertension, Age  6575 years, Diabetes mellitus, previous Stroke, Vascular disease, Age 65 to 74 years, Sex category] score  652; 86.1%); 13.9% had moderate risk (CHA2DS2-VASc = 1). Overall, 79.9% received oral anticoagulants, of whom 47.6% received NOAC and 32.3% vitamin K antagonists (VKA); 12.1% received antiplatelet agents; 7.8% received no antithrombotic treatment. For comparison, the proportion of phase 1 patients (of N = 1,063 all eligible) prescribed VKA was 32.8%, acetylsalicylic acid 41.7%, and no therapy 20.2%. In Europe in phase 2, treatment with NOAC was more common than VKA (52.3% and 37.8%, respectively); 6.0% of patients received antiplatelet treatment; and 3.8% received no antithrombotic treatment. In North America, 52.1%, 26.2%, and 14.0% of patients received NOAC, VKA, and antiplatelet drugs, respectively; 7.5% received no antithrombotic treatment. NOAC use was less common in Asia (27.7%), where 27.5% of patients received VKA, 25.0% antiplatelet drugs, and 19.8% no antithrombotic treatment. Conclusions The baseline data from GLORIA-AF phase 2 demonstrate that in newly diagnosed nonvalvular atrial fibrillation patients, NOAC have been highly adopted into practice, becoming more frequently prescribed than VKA in Europe and North America. Worldwide, however, a large proportion of patients remain undertreated, particularly in Asia and North America. (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients With Atrial Fibrillation [GLORIA-AF]; NCT01468701

Interaction between gas flow and a Lamb waves based sensors

International audienceThe interaction between the gas flow and Lamb waves is investigated in this paper. Depending on the fact that the phase velocity is higher or lower than the gas sound velocity, we will get evanescent waves (EW) or leaky Lamb waves (LLW) in the gas along the solid–gas interface. In the LLW case, experiments showed that gas flow had not evident effects on Lamb waves’ propagations. In the EW case, the interaction between the gas flow and the Lamb waves was observed clearly when the Lamb wave phase velocity is close to the gas sound velocity. This interaction is related with the gas flow velocity profile within the boundary layer. The experimental results show that this sensor is very promising for many experiments involving gas flows such in wind tunnels, micro channels characterization, and can lead to multi-parameters measurements

Influence of gases on Lamb waves propagations in resonator

International audienceWe investigate gases effects on the Lamb wave resonant modes. Various frequency ranges are studied for the antisymmetric mode considering wave velocities either higher or lower than the gas sound velocity. We observe that the relative frequency shifts in the low frequency range of the antisymmetric mode is rather important; in the high frequency range of this mode, the quality factor decreases quickly when the Lamb wave phase velocity approaches the gas sound velocity. We find a good agreement between calculations and experiments in air and helium. The results suggest the possibility to get aerodynamics parameters of gas flow

A Multi-Parameter Decoupling Method with a Lamb Wave Sensor for Improving the Selectivity of Label-Free Liquid Detection †

sensor

A review of perovskite photovoltaic materials' synthesis and applications via chemical vapor deposition method

Perovskite photovoltaic materials (PPMs) have emerged as one of superstar object for applications in photovoltaics due to their excellent properties-such as band-gap tunability, high carrier mobility, high optical gain, astrong nonlinear response-as well as simplicity of their integration with other types of optical and electronic structures. Meanwhile, PPMS and their constructed devices still present many challenges, such as stability, repeatability, and large area fabrication methods and so on. The key issue is: how can PPMs be prepared using an effective way which most of the readers care about. Chemical vapor deposition (CVD) technology with high efficiency, controllability, and repeatability has been regarded as a cost-effective road for fabricating high quality perovskites. This paper provides an overview of the recent progress in the synthesis and application of various PPMs via the CVD method. We mainly summarize the influence of different CVD technologies and important experimental parameters (temperature, pressure, growth environment, etc.) on the stabilization, structural design, and performance optimization of PPMS and devices. Furthermore, current challenges in the synthesis and application of PPMS using the CVD method are highlighted with suggested areas for future research.Published versio

Properties and Applications of the β Phase Poly(vinylidene fluoride)

Poly(vinylidene fluoride), PVDF, as one of important polymeric materials with extensively scientific interests and technological applications, shows five crystalline polymorphs with α, β, γ, δ and ε phases obtained by different processing methods. Among them, β phase PVDF presents outstanding electrical characteristics including piezo-, pyro-and ferroelectric properties. These electroactive properties are increasingly important in applications such as energy storage, spin valve devices, biomedicine, sensors and smart scaffolds. This article discusses the basic knowledge and character methods for PVDF fabrication and provides an overview of recent advances on the phase modification and recent applications of the β phase PVDF are reported. This study may provide an insight for the development and utilization for β phase PVDF nanofilms in future electronics

Magnetoresistance Effect and the Applications for Organic Spin Valves Using Molecular Spacers

Organic spin devices utilizing the properties of both spin and charge inherent in electrons have attracted extensive research interest in the field of future electronic device development. In the last decade, magnetoresistance effects, including giant magetoresistance and tunneling magnetoresistance, have been observed in organic spintronics. Significant progress has been made in understanding spin-dependent transport phenomena, such as spin injection or tunneling, manipulation, and detection in organic spintronics. However, to date, materials that are effective for preparing organic spin devices for commercial applications are still lacking. In this report, we introduce basic knowledge of the fabrication and evaluation of organic spin devices, and review some remarkable applications for organic spin valves using molecular spacers. The current bottlenecks that hinder further enhancement for the performance of organic spin devices is also discussed. This report presents some research ideas for designing organic spin devices operated at room temperature