Bending Stability of Ferroelectric Gated Graphene Field Effect Transistor for Flexible Electronics.

In this work, we explored the potential of the ferroelectric gate of (Pb0.92La0.08)(Zr0.30Ti0.70)O3 (PLZT(8/30/70)) for flexible graphene field effect transistor (GFET) devices. Based on the deep understanding of the VDirac of PLZT(8/30/70) gate GFET, which determines the application of the flexible GFET devices, the polarization mechanisms of PLZT(8/30/70) under bending deformation were analyzed. It was found that both flexoelectric polarization and piezoelectric polarization exist under bending deformation, and their polarization direction is opposite under the same bending deformation. Thus, a relatively stable of VDirac is obtained due to the combination of these two effects. In contrast to the relatively good linear movement of VDirac under bending deformation of relaxor ferroelectric (Pb0.92La0.08)(Zr0.52Ti0.48)O3 (PLZT(8/52/48)) gated GFET, these stable properties of the PLZT(8/30/70) gate GFETs make them have great potential for applications in flexible devices.

Improved Leakage Behavior at High Temperature via Engineering of Ferroelectric Sandwich Structures.

The leakage behavior of ferroelectric film has an important effect on energy storage characteristics. Understanding and controlling the leakage mechanism of ferroelectric film at different temperatures can effectively improve its wide-temperature storage performance. Here, the structures of a 1 mol% SiO2-doped BaZr0.35Ti0.65O3 (BZTS) layer sandwiched between two undoped BaZr0.35Ti0.65O3 (BZT35) layers was demonstrated, and the leakage mechanism was analyzed compared with BZT35 and BZTS single-layer film. It was found that interface-limited conduction of Schottky (S) emission and the Fowler-Nordheim (F-N) tunneling existing in BZT35 and BZTS films under high temperature and a high electric field are the main source of the increase of leakage current and the decrease of energy storage efficiency at high temperature. Only an ohmic conductive mechanism exists in the whole temperature range of BZT35/BZTS/BZT35(1:1:1) sandwich structure films, indicating that sandwich multilayer films can effectively simulate the occurrence of interface-limited conductive mechanisms and mention the energy storage characteristics under high temperature.

Early Prediction Model of Acute Aortic Syndrome Mortality in Emergency Departments.

Purpose: Acute aortic syndrome is a constellation of life-threatening medical conditions for which rapid assessment and targeted intervention are important for the prognosis of patients who are at high risk of in-hospital death. The current study aims to develop and externally validate an early prediction mortality model that can be used to identify high-risk patients with acute aortic syndrome in the emergency department. Patients and Methods: This retrospective multi-center observational study enrolled 1088 patients with acute aortic syndrome admitted to the emergency departments of two hospitals in China between January 2017 and March 2021 for model development. A total of 210 patients with acute aortic syndrome admitted to the emergency departments of Peking University Third Hospital between January 2007 and December 2021 was enrolled for model validation. Demographics and clinical factors were collected at the time of emergency department admission. The predictive variables were determined by referring to the results of previous studies and the baseline analysis of this study. The study's endpoint was in-hospital death. To assess internal validity, we used a fivefold cross-validation method. Model performance was validated internally and externally by evaluating model discrimination using the area under the receiver-operating characteristic curve (AUC). A nomogram was developed based on the binary regression results. Results: In the development cohort, 1088 patients with acute aortic syndromes were included, and 88 (8.1%) patients died during hospitalization. In the validation cohort, 210 patients were included, and 20 (9.5%) patients died during hospitalization. The final model included the following variables: digestive system symptoms (OR=2.25; P=0.024), any pulse deficit (OR=7.78; P<0.001), creatinine (µmol/L)(OR=1.00; P=0.018), lesion extension to iliac vessels (OR=4.49; P<0.001), pericardial effusion (OR=2.67; P=0.008), and Stanford type A (OR=10.46; P<0.001). The model's AUC was 0.838 (95% CI 0.784-0.892) in the development cohort and 0.821 (95% CI 0.750-0.891) in the validation cohort, and the Hosmer-Lemeshow test showed p=0.597. The fivefold cross-validation demonstrated a mean accuracy of 0.94, a mean precision of 0.67, and a mean recall of 0.13. Conclusion: This risk prediction tool uses simple variables to provide robust prediction of the risk of in-hospital death from acute aortic syndrome and validated well in an independent cohort. The tool can help emergency clinicians quickly identify high-risk acute aortic syndrome patients, although further studies are needed for verifying the prospective data and the results of our study.

Ultrahigh Temperature Lead-Free Film Capacitors via Strain and Dielectric Constant Double Gradient Design.

With the development of miniaturization, lightweight and integration of electronic devices, the demand for high-temperature dielectric capacitors is becoming urgent. Nevertheless, the breakdown strength and polarization are deteriorated at high temperatures due to the thermal energy assisting the electron transport and impeding the dipole alignment. Here, a structure of capacitor with double gradients of dielectric constant gradient and strain gradient is designed to achieve high breakdown strength, high working temperature, and high energy storage density simultaneously. It is found that the designed structure of BaHf0.17 Ti0.83 O3 /1mol% SiO2 doped BaZr0.35 Ti0.65 O3 /0.85BaTiO3 -0.15Bi(Mg0.5 Zr0.5 )O3 exhibits excellent energy storage performance. The energy storage density of 127.3 J cm-3 with an energy storage efficiency of 79.6% is realized in the up-sequence multilayer with period N = 2 at room temperature. Moreover, when the working temperature varies from -100 to 200 °C, the energy storage density of the N = 4 capacitor keeps stably at 84.62 J cm-3 with an energy storage efficiency 78.42% at 6.86 MV cm-1 . All these properties promise great potential applications of the designed multilayer capacitors with the double gradients in harsh environments, and the design principle can be applicable to other systems to boost working temperature.

Increased Serum Neuropeptide Galanin Level Is a Predictor of Cognitive Dysfunction in Patients with Hip Fracture.

BACKGROUND: Hip fracture is a common occurrence in elderly populations and is frequently followed by various levels of cognitive dysfunction, leading to adverse functional outcomes. Risk stratification of hip fracture patients to identify high-risk subsets can enable improved strategies to mitigate cognitive complications. The neuropeptide galanin has multiple neurological functions, and altered levels are documented in dementia-type and depression disorders. The present study investigated the association of serum neuropeptide galanin levels in hip fracture patients with the occurrence of cognitive dysfunction during the first week of admission. METHODS: 276 hip fracture patients without preexisting delirium, cognitive impairment, or severe mental disorders were included in a cross-sectional study. Serum galanin levels were assessed by ELISA on the second day of admission. Routine clinical and laboratory variables were documented. MoCA was performed within 1 week, and those with a score < 26 were categorized with "cognitive decline." Inferential statistics including multiple linear regression analysis were applied to determine the association of serum galanin level and cognitive status. RESULTS: 141 patients were categorized with "cognitive decline," and 135 patients were categorized as "cognitively normal." Serum galanin was highly significantly increased in the "cognitive decline" group (34.2 ± 4.8, pg/ml) compared to the "cognitively normal" group (28.9 ± 3.7, pg/ml) and showed significant negative correlation with MoCA scores (r = -0.229, p = 0.016). Regression analysis showed serum galanin as the sole significant independent predictor of lower MoCA scores (ß = 0.231, p = 0.035) while age, gender, blood pressure, cholesterol, and blood glucose levels had no significant association. CONCLUSION: Higher serum galanin predicted the development of cognitive dysfunction and worse MoCA scores in a cohort of hip fracture patients without preexisting cognitive impairment or delirium at admission, thus warranting large-scale studies investigating galanin as a candidate biomarker to identify hip fracture patients at risk of cognitive decline.

Multilayer Structured Poly(vinylidene fluoride)-Based Composite Film with Ultrahigh Breakdown Strength and Discharged Energy Density.

Poly(vinylidene fluoride)-based (PVDF) composites with high discharged energy density (Ue) have been considered as advanced dielectric materials for pulsed power systems and electrical weapon systems. However, further improvement of the Ue of PVDF-based composites with higher breakdown strength (Eb) is of utmost importance. Based on the principle of voltage distribution in the multilayer structure, the multilayer structure (five-layer structure) ceramic/polymer composite films consisting of pristine PVDF layers with high breakdown strength and PVDF layers doped with one-dimensional 0.15SrTiO3-0.85Na0.5Bi0.5TiO3 (1D SNBT) fibers where the two kinds of layers stacked alternately has been designed and fabricated. Accordingly, a series of analyses of the dielectric properties and energy storage performances are presented, and the related results are tentatively explained by finite element simulation. The energy storage characteristics of the composite films are greatly improved due to the newly designed structure. An excellent Ue of 20.82 J cm-3 is achieved at an ultrahigh electric field of 640 MV m-1 with the PVDF layers containing 6 vol % SNBT fibers. Therefore, this work provides a new strategy to design and fabricate advanced polymer-based energy storage materials.

Self-Organization of Ions at the Interface between Graphene and Ionic Liquid DEME-TFSI.

Electrochemical effects manifest as nonlinear responses to an applied electric field in electrochemical devices, and are linked intimately to the molecular orientation of ions in the electric double layer (EDL). Herein, we probe the origin of the electrochemical effect using a double-gate graphene field effect transistor (GFET) of ionic liquid N,N-diethyl-N-(2-methoxyethyl)-N-methylammonium bis(trifluoromethylsulfonyl)imide (DEME-TFSI) top-gate, paired with a ferroelectric Pb0.92La0.08Zr0.52Ti0.48O3 (PLZT) back-gate of compatible gating efficiency. The orientation of the interfacial molecular ions can be extracted by measuring the GFET Dirac point shift, and their dynamic response to ultraviolet-visible light and a gate electric field was quantified. We have observed that the strong electrochemical effect is due to the TFSI anions self-organizing on a treated GFET surface. Moreover, a reversible order-disorder transition of TFSI anions self-organized on the GFET surface can be triggered by illuminating the interface with ultraviolet-visible light, revealing that it is a useful method to control the surface ion configuration and the overall performance of the device.

Detecting Electric Dipoles Interaction at the Interface of Ferroelectric and Electrolyte Using Graphene Field Effect Transistors.

Graphene was inserted into the interface between electric dipole layers from DEME-TFSI ionic liquid (top-gate) and ferroelectric Pb0.92La0.08Zr0.52Ti0.48O3 (PLZT, back-gate) to probe the interface dipole-dipole interaction in response to DC and pulsed gate voltages. A highly complicated behavior of the interface dipole-dipole interaction has been revealed as a combination of electrostatic and electrochemical effects. The interfacial polar molecules in the DEME-TFSI electrical double layer are pinned with assistance from the PLZT back-gate in response to a DC top-gate pump, leading to strong nonlinear electrochemical behavior. In contrast, depinning of these molecules can be facilitated by a faster pulsed top-gate pump, which results in a characteristic linear electrostatic behavior. This result not only sheds light on the dynamic dipole-dipole interactions on the interface between functional materials but also prototypes a unique pump and probe approach using graphene field effect transistors to detect the interface dipole-dipole interaction.

Anti-wear properties of the molluscan shell Scapharca subcrenata: influence of surface morphology, structure and organic material on the elementary wear process.

As a typical natural biological mineralisation material, molluscan shells have excellent wear-resistance properties that result from the interactions amongst biological coupling elements such as morphology, structure and material. The in-depth study of the wear-resistance performance of shells and the contribution made by each coupling element may help to promote the development of new bionic wear-resistant devices. The objective of this study was to investigate the influence of surface morphology (rib distribution on the shell), structure (rib coupled with nodules) and material (organic matter) on the anti-wear performance of the molluscan Scapharca subcrenata shell. The effect and contribution of each of these biological coupling elements were systematically investigated using the comparative experiment method. All three were found to exert significant effects on the shell's wear-resistance ability, and their individual contributions to that ability were revealed. Organic material can be classified as the principal coupling element, rib morphology as the secondary coupling element and the combined rib-nodule structure as the general coupling element.

[Flavectomy of cervical vertebrae in treating cervical spinal canal stenosis].

OBJECTIVE: To investigate the operational method of cervical vertebral flavectomy and its clinical application in the management of cervical canal stenosis. METHODS: From June 1997 to June 2007, 25 patients suffering from cervical spinal canal stenosis caused by obvious flaval ligament hypertrophy were given flavectomy. There were 22 males and 3 females, with an age range of 32 to 68 years (average 54 years). The course of disease was from 3 weeks to 7 years, with an average of 3 years and 7 months. All patients had degenerative cervical canal stenosis; of them, 5 cases had a history of cervical injury 2 to 3 weeks before operation (3 cases of falling injury and 2 cases of traffic accident injury). The X-ray film, CT, and MRI examinations showed that the compression locations were C4-7 in 12 cases, C3-7 in 9 cases, C5-7 in 3 cases, and C6,7 in 1 case. Spinous process and vertebral lamella were exposed by central posterior approach. The insertions of flaval ligaments were cut off at the superior vertebral lamella border, then the starting points of which were cut down from the anterior side of the upper vertebral lamella at their inferior border after lifting up the flaval ligaments. The residual flaval ligaments in front of the vertebral lamella were scraped off by slope rongeur, the dura mater then could be seen to inflate from the intervertebral lamella space, showing the compression having been relieved. Twenty-five cases were all given posterior flavectomy. At 1 week to 3 months after operation, 12 patients received anterior cervical discectomy or vertebral gaining decompression with fusion by bone graft. RESULTS: The time for flavectomy was from 60 to 180 minutes, with an average of 95 minutes. The blood loss during operation was from 90 to 360 mL, with an average of 210 mL. The dura matters were lacerated by knife tips during operation with the cervical vertebrae in hyperflexion in 2 cases. Immediate suture and repair were performed and there were no postoperative cerebrospinal fluid leakage. All the incisions healed by first intension after operation. All of the 25 cases were followed up from 2 to 10 years, with an average of 3 years and 9 months. All patients had no complication of axial symptoms, and no restenosis at their operation site of cervical canal stenosis. The section area ratios of functional spinal canal to spinal cord were 1.12 +/- 0.07 before operation and 2.11 +/- 0.19 at 24 months after operation, showing significant difference (P < 0.05). The range of motion of cervical vertebrae was (39.4 +/- 3.2) degrees before operation and (42.1 +/- 2.9) degrees at 24 months after operation in 13 cases without anterior cervical discectomy fusion, showing no significant difference (P > 0.05); was (34.3 +/- 3.4) degrees before operation and (29.2 +/- 3.6) degrees at 24 months after operation in 12 cases with anterior cervical discectomy fusion, showing significant difference (P < 0.05). The bone graft achieved bony union 3-5 months after operation (average 3.8 months). The Japanese Orthopaedic Association (JOA) scores were 7.9 +/- 2.2 before operation and 15.6 +/- 1.4 at 24 months after operation, showing significant difference (P < 0.05), with an average improvement rate of 86.3%. CONCLUSION: Cervical flavectomy could relieve compression to spinal cord and nerves caused by the flaval ligament hypertrophy without damaging the normal integrality of bony canal, thus avoiding the complication of axial symptoms and so on which are encountered in open-door expansile cervical laminoplasty.