Interface-induced dual-pinning mechanism enhances low-frequency electromagnetic wave loss.

Improving the absorption of electromagnetic waves at low-frequency bands (2-8 GHz) is crucial for the increasing electromagnetic (EM) pollution brought about by the innovation of the fifth generation (5G) communication technology. However, the poor impedance matching and intrinsic attenuation of material in low-frequency bands hinders the development of low-frequency electromagnetic wave absorbing (EMWA) materials. Here we propose an interface-induced dual-pinning mechanism and establish a magnetoelectric bias interface by constructing bilayer core-shell structures of NiFe2O4 (NFO)@BiFeO3 (BFO)@polypyrrole (PPy). Such heterogeneous interface could induce distinct magnetic pinning of the magnetic moment in the ferromagnetic NFO and dielectric pinning of the dipole rotation in PPy. The establishment of the dual-pinning effect resulted in optimized impedance and enhanced attenuation at low-frequency bands, leading to better EMWA performance. The minimum reflection loss (RLmin) at thickness of 4.43 mm reaches -65.30 dB (the optimal absorption efficiency of 99.99997%), and the effective absorption bandwidth (EAB) can almost cover C-band (4.72 ~ 7.04 GHz) with low filling of 15.0 wt.%. This work proposes a mechanism to optimize low-frequency impedance matching with electromagnetic wave (EMW) loss and pave an avenue for the research of high-performance low-frequency absorbers.

Plasmonic nanosensor and pressure-induced transparency based on coupled resonator in a nanoscale system.

Plasmonic nanosensors and the dynamic control of light fields are of the utmost significance in the field of micro- and nano-optics. Here, our study successfully demonstrates a plasmonic nanosensor in a compact coupled resonator system and obtains the pressure-induced transparency phenomenon for the first time to our knowledge. The proposed structure consists of a groove and slot cavity coupled in the metal-insulator-metal waveguide, whose mechanical and optical characteristics are investigated in detail using the finite element method. Simulation results show that we construct a quantitative relationship among the resonator deformation quantity, the applied pressure variation, and the resonant wavelength offset by combining the mechanical and optical properties of the proposed system. The physical features contribute to highly efficient plasmonic nanosensors for refractive index and optical pressure sensing with sensitivity of 1800 nm/RIU and 7.4 nm/MPa, respectively. Furthermore, the light waves are coupled to each other in the resonators, which are detuned due to the presence of pressure, resulting in the pressure-induced transparency phenomenon. It is noteworthy to emphasize that, unlike previously published works, our numerical results take structural deformation-induced changes in optical properties into account, making them trustworthy and practical. The proposed structure introduces a novel, to the best of our knowledge, approach for the dynamic control of light fields and has special properties that can be utilized for the realization of various integrated components.

[Effect of High-Concentration Uric Acid on Nitric Oxide].

Uric acid (UA) is the final product of purine metabolism in human body,and its metabolic disorder will induce hyperuricemia (HUA).The occurrence and development of HUA are associated with a variety of pathological mechanisms such as oxidative stress injury,activation of inflammatory cytokines,and activation of renin-angiotensin-aldosterone system.These mechanisms directly or indirectly affect the bioavailability of endogenous nitric oxide (NO).The decrease in NO bioavailability is common in the diseases with high concentration of UA as an independent risk factor.In this review,we summarize the mechanisms by which high concentrations of UA affect the endogenous NO bioavailability,with a focus on the mechanisms of high-concentration UA in decreasing the synthesis and/or increasing the consumption of NO.This review aims to provide references for alleviating the multisystem symptoms and improving the prognosis of HUA,and lay a theoretical foundation for in-depth study of the correlations between HUA and other metabolic diseases.

A Novel Strategy for Detecting Permittivity and Loss Tangent of Low-Loss Materials Based on Cylindrical Resonant Cavity.

Accurate measurement of the permittivity and loss tangent of low-loss materials is essential due to their special applications in the field of ultra large scale integrated circuits and microwave devices. In this study, we developed a novel strategy that can accurately detect the permittivity and loss tangent of low-loss materials based on a cylindrical resonant cavity supporting the TE111 mode in X band (8-12 GHz). Based on an electromagnetic field simulation calculation of the cylindrical resonator, permittivity is precisely retrieved by exploring and analyzing the perturbation of the coupling hole and sample size on the cutoff wavenumber. A more precise approach to measuring the loss tangent of samples with various thicknesses has been proposed. The test results of the standard samples verify that this method can accurately measure the dielectric properties of samples that have smaller sizes than the high Q cylindrical cavity method.

Fascinating Electrical Transport Behavior of Topological Insulator Bi2 Te3 Nanorods: Toward Electrically Responsive Smart Materials.

Electrical conductivity and dielectric parameters are general inherent features of materials. Controlling these characteristics through applied bias will add a new dimension to regulate the dynamic response of smart materials. Here, a fascinating electrical transport behavior is observed in topological insulator (TI) Bi2 Te3 nanorods, which will play a vital role in intelligent materials or devices as a unit for information reception, processing or feedback. The Bi2 Te3 nanorod aggregates exhibit a monotonic resistance response to voltage, with observed four-fold change of electrical conductivity in a small range electric field of 1 V mm-1 . The dielectric constant and dielectric loss of Bi2 Te3 nanorod composites also show strong dependences on bias voltage due to the unique electrical transport characteristics. The unique voltage-controlled electrical responses are attributed to the change of Fermi levels within the band structure of disordered TI nanorods, which are non-parallel to the applied electric field. The excellent controllable inherent characteristics through electric field endows Bi2 Te3 nanomaterials bright prospects for applications in smart devices and resistive random access memories.

A highly conductive self-assembled multilayer graphene nanosheet film for electronic tattoos in the applications of human electrophysiology and strain sensing.

Highly conductive, conformable and gel-free electrodes are desirable in human electrophysiology. Besides, intimately coupling with human skin, wearable strain sensors can detect numerous physiological signals, such as wrist pulse and breath. In this study, a multilayer graphene nanosheet film (MGNF) with high conductivity was prepared by the Marangoni self-assembly for using in tattoo dry electrodes (TDEs) and in a graphene tattoo strain sensor (GTSS). Compared to commercial Ag/AgCl gel electrodes, TDEs have lower skin-electrode contact impedance and could detect human electrocardiogram for 24-hour wearing more accurately as well as electromyogram. Through designing a slim serpentine ribbon structure, a resistance-type GTSS, without deterioration even after 2000 cycles, is well demonstrated for human wrist pulse and breath sensing. With the advantages of high conductivity and conformability, MGNF provides support to fabricate low-cost, customizable, and high-performance electronic tattoos for human electrophysiology and strain sensing.

High-Sensitivity and Ultrafast-Response Ethanol Sensors Based on Graphene Oxide.

Ethanol sensors with ultrafast response and high sensitivity have attracted much attention to be applied to daily industrial production processes. In this work, graphene oxide-aniline (GOA) sensors are proposed to meet the requirements of detecting ethanol concentration. Graphene oxide is an outstanding material that has excellent electrical and thermal conductivity, large specific surface area, and high carrier mobility. Because of its special bonding reactions, GOA has advantages of good dispersibility, good electrical conductivity, insolubility in water, and strong plasticity. When testing ethanol concentration with sensors, there will be a lag time, which determines the sensitivity of the sensors. To the best of our knowledge, the GOA sensors in this work have the fastest response time, which is only 27 ms. The GOA ethanol sensors show a good ethanol sensing performance, including excellent sensitivity, cycle stability, and long-term stability.

Effectiveness of electroacupuncture for pain after osteosarcoma post surgery: A study protocol of systematic review of randomized controlled trial.

BACKGROUND: This study will assess the effectiveness of electroacupuncture (EA) for pain in patients with osteosarcoma post surgery (OSPS). METHODS: In this study, we will comprehensively search the following electronic databases from inception to the present without language restrictions: Cochrane Library, EMBASE, MEDLINE, the Cumulative Index to Nursing and Allied Health Literature, the Allied and Complementary Medicine Database, and Chinese Biomedical Literature Database. Two authors will independently carry out study selection, data extraction, and methodological assessments. RevMan 5.3 software will be used for statistical analysis. RESULTS: The primary outcome is pain intensity. The secondary outcomes consist of event-free survival, overall survival, quality of life, and adverse events. CONCLUSION: The findings of this study will provide helpful evidence of EA treatment for patients with OSPS. PROSPERO REGISTRATION NUMBER: PROSPERO CRD42019146696.

Ultrathin Topological Insulator Absorber: Unique Dielectric Behavior of Bi2Te3 Nanosheets Based on Conducting Surface States.

Topological insulators exhibit great potential in the fields of electronics and semiconductors for their gapless surface states. Intriguingly, most topological insulators are possibly excellent microwave-absorbing materials because of easy adjustment of electrical transport based on conducting surface states in the nanostructure. Herein, topological insulator Bi2Te3 nanosheets are synthesized by a simple solvothermal method. The material demonstrates a unique dielectric behavior based on conducting surface states, resulting in excellent microwave-absorbing performance. Benefiting from the outstanding impedance matching, Bi2Te3 nanosheets exhibit an ultrathin microwave absorption with the qualified frequency bandwidth of 3.0 GHz at only 0.77 mm thickness, which is thinner than other absorbers in reported references. Moreover, a strong reflection loss of -41 dB at 0.8 mm is achieved. The result provides a new approach for developing ultrathin microwave absorption materials at the submillimeter scale.

Efficacy of Duohuojisheng decoction monotherapy for the treatment of knee osteoarthritis: A protocol of a systematic review of randomized controlled trials.

BACKGROUND: This systematic review investigates the efficacy and safety of Duohuojisheng decoction (DHJSD) monotherapy for the treatment of patients with knee osteoarthritis (KOA). METHODS: We searched relevant studies on DHJSD monotherapy for KOA from the databases of CENTRAL, EMBASE, MEDLINE, Cumulative Index to Nursing and Allied Health Literature, Allied and Complementary Medicine Database, Chinese Biomedical Literature Database, China National Knowledge Infrastructure, VIP Information, and Wanfang Data from the inception to January 1, 2019. Two researchers independently selected studies, collected data, and assessed the methodology quality by using Cochrane risk of bias tool. RESULTS: This study evaluates the efficacy and safety of DHJSD monotherapy for KOA by assessing the pain intensity, stiffness, and disability of affected knee joints, and quality of life, as well as the adverse events. CONCLUSION: The results of this study provide latest updated evidence of DHJSD monotherapy alone for KOA. ETHICS AND DISSEMINATION: No ethical approval is required for this systematic review, because it is based on the published data, and not on individual patient data. Its findings is published in a peer-reviewed journal. PROSPERO REGISTRATION NUMBER: PROSPERO CRD42019120405.

Efficacy of methotrexate, doxorubicin, and cisplatin for osteosarcoma: Study protocol for a systematic review of randomized controlled trial.

BACKGROUND: This systematic review will address the efficacy and safety of methotrexate, doxorubicin, and cisplatin (MAP) for the treatment of patients with osteosarcoma. METHODS: We will retrieve the studies from the following 9 electronic databases: Cochrane Central Register of Controlled Trials, EMBASE, MEDLINE, the Cumulative Index to Nursing and Allied Health Literature, the Allied and Complementary Medicine Database, and Chinese Biomedical Literature Database, China National Knowledge Infrastructure, VIP Information, and Wanfang Data. Two independent researchers will screen and select the relevant papers for eligibility after the search strategies have been conducted. All articles up to the present in any language, region will be considered in this study. A systematic review and data synthesis will be performed of randomized controlled trials of MAP for the treatment of patients with osteosarcoma. The primary outcome includes event-free survival. The secondary outcomes consist of overall survival, quality of life, and toxicity. In addition, 2 independent researchers will extract data, and will assess the quality of included studies by using Cochrane risk of bias tool. Results data will be pooled and meta-analysis will be conducted if >2 eligible studies will be included. RESULTS: This systematic review will evaluate the efficacy and safety of MAP for the treatment of patients with osteosarcoma. CONCLUSION: The findings of this study will summarize the up-to-date evidence of MAP for osteosarcoma, and may provide the guidance for the clinical practice, as well as the health policy maker. PROSPERO REGISTRATION NUMBER: PROSPERO CRD42018120004.

Effect of knee joint function training on joint functional rehabilitation after knee replacement.

This retrospective study investigated the effect of knee joint function training (KJFT) on joint functional rehabilitation after knee replacement in Chinese patients with severe knee osteoarthritis (KOA).Eighty-six eligible patients with severe KOA were included. Of those, 43 patients in the intervention group received KJFT and educational program, while the other 43 patients received educational program only. Primary outcome was measured by the Western Ontario and McMaster Universities Arthritis Index (WOMAC). Secondary outcomes were measured by the visual analogue scale (VAS), and Knee Injury and Osteoarthritis Outcome Score (KOOS). All outcomes were assessed at baseline, 1 week before and 3 months after the surgery.Patients in the intervention group showed encouraging benefit neither at 1 week before nor 3 months after the surgery in all outcome measurements, including WOMAC, VAS, and KOOS, when compared with the patients in the control group.The results of this study did not show promising effect of KJFT for joint functional rehabilitation in Chinese patients with KOA after KJR.

Flexible Semitransparent Energy Harvester with High Pressure Sensitivity and Power Density Based on Laterally Aligned PZT Single-Crystal Nanowires.

A flexible semitransparent energy harvester is assembled based on laterally aligned Pb(Zr0.52Ti0.48)O3 (PZT) single-crystal nanowires (NWs). Such a harvester presents the highest open-circuit voltage and a stable area power density of up to 10 V and 0.27 µW/cm2, respectively. A high pressure sensitivity of 0.14 V/kPa is obtained in the dynamic pressure sensing, much larger than the values reported in other energy harvesters based on piezoelectric single-crystal NWs. Furthermore, theoretical and finite element analyses also confirm that the piezoelectric voltage constant g33 of PZT NWs is competitive to the lead-based bulk single crystals and ceramics, and the enhanced pressure sensitivity and power density are substantially linked to the flexible structure with laterally aligned PZT NWs. The energy harvester in this work holds great potential in flexible and transparent sensing and self-powered systems.

Construction of three-dimensional graphene interfaces into carbon fiber textiles for increasing deposition of nickel nanoparticles: flexible hierarchical magnetic textile composites for strong electromagnetic shielding.

Since manipulating electromagnetic waves with electromagnetic active materials for environmental and electric engineering is a significant task, here a novel prototype is reported by introducing reduced graphene oxide (RGO) interfaces in carbon fiber (CF) networks for a hierarchical carbon fiber/reduced graphene oxide/nickel (CF-RGO-Ni) composite textile. Upon charaterizations of the microscopic morphologies, electrical and magnetic properties, the presence of three-dimensional RGO interfaces and bifunctional nickel nanoparticles substantially influences the related physical properties in the resulting hierarchical composite textiles. Eletromagnetic interference (EMI) shielding performance suggests that the hierarchical composite textiles hold a strong shielding effectiveness greater than 61 dB, showing greater advantages than conventional polymeric and foamy shielding composites. As a polymer-free lightweight structure, flexible CF-RGO-Ni composites of all electromagnetic active components offer unique understanding of the multi-scale and multiple mechanisms in electromagnetic energy consumption. Such a novel prototype of shielding structures along with convenient technology highlight a strategy to achieve high-performance EMI shielding, coupled with a universal approach for preparing advanced lightweight composites with graphene interfaces.

Unusual continuous dual absorption peaks in Ca-doped BiFeO3 nanostructures for broadened microwave absorption.

Electromagnetic absorption materials have received increasing attention owing to their wide applications in aerospace, communication and the electronics industry, and multiferroic materials with both polarization and magnetic properties are considered promising ceramics for microwave absorption application. However, the insufficient absorption intensity coupled with the narrow effective absorption bandwidth has limited the development of high-performance multiferroic materials for practical microwave absorption. To address such issues, in the present work, we utilize interfacial engineering in BiFeO3 nanoparticles via Ca doping, with the purpose of tailoring the phase boundary. Upon Ca-substitution, the co-existence of both R3c and P4mm phases has been confirmed to massively enhance both dielectric and magnetic properties via manipulating the phase boundary and the destruction of the spiral spin structure. Unlike the commonly reported magnetic/dielectric hybrid microwave absorption composites, Bi0.95Ca0.05FeO3 has been found to deliver unusual continuous dual absorption peaks at a small thickness (1.56 mm), which has remarkably broadened the effective absorption bandwidth (8.7-12.1 GHz). The fundamental mechanisms based on the phase boundary engineering have been discussed, suggesting a novel platform for designing advanced multiferroic materials with wide applications.

Enhanced Fluorescence Properties of Carbon Dots in Polymer Films.

Carbon dots of small carbon nanoparticles surface-functionalized with 2,2'-(ethylenedioxy)bis(ethylamine) (EDA) were synthesized, and the as-synthesized sample was separated on an aqueous gel column to obtain fractions of the EDA-carbon dots with different fluorescence quantum yields. As already discussed in the literature, the variations in fluorescence performance among the fractions were attributed to the different levels and/or effectiveness of the surface functionalization-passivation in the carbon dots. These fractions, as well as carbon nanoparticles without any deliberate surface functionalization, were dispersed into poly(vinyl alcohol) (PVA) for composite films. In the PVA film matrix, the carbon dots and nanoparticles exhibited much enhanced fluorescence emissions in comparison with their corresponding aqueous solutions. The increased fluorescence quantum yields in the films were determined quantitatively by using a specifically designed and constructed film sample holder in the emission spectrometer. The observed fluorescence decays of the EDA-carbon dots in film and in solution were essentially the same, suggesting that the significant enhancement in fluorescence quantum yields from solution to film is static in nature. Mechanistic implications of the results, including a rationalization in terms of the compression effect on the surface passivation layer (similar to a soft corona) in carbon dots when embedded in the more restrictive film environment resulting in more favorable radiative recombinations of the carbon particle surface-trapped electrons and holes, and also potential technological applications of the brightly fluorescent composite films are highlighted and discussed.

Flexible graphene-graphene composites of superior thermal and electrical transport properties.

Graphene is known for high thermal and electrical conductivities. In the preparation of neat carbon materials based on graphene, a common approach has been the use of well-exfoliated graphene oxides (GOs) as the precursor, followed by conversion to reduced GOs (rGOs). However, rGOs are more suitable for the targeted high electrical conductivity achievable through percolation but considerably less effective in terms of efficient thermal transport dictated by phonon progression. In this work, neat carbon films were fabricated directly from few-layer graphene sheets, avoiding rGOs completely. These essentially graphene-graphene composites were of a metal-like appearance and mechanically flexible, exhibiting superior thermal and electrical transport properties. The observed thermal and electrical conductivities are higher than 220 W/m · K and 85000 S/m, respectively. Some issues in the further development of these mechanically flexible graphene-graphene nanocomposite materials are discussed and so are the associated opportunities.

Alignment of graphene sheets in wax composites for electromagnetic interference shielding improvement.

Rapid advancements in carbon-based fillers have enabled a new and more promising platform in the development of electromagnetic attenuation composites. Alignment of fillers in composites with specific structures and morphologies has been widely pursued to achieve high performance based on taking advantage of unique filler characteristics. In this work, few-layer graphene (FLG), obtained from direct exfoliation of graphite, was fabricated into paraffin wax to prepare FLG/wax composites and investigate their electromagnetic interference (EMI) shielding performance. The as-exfoliated FLG/wax samples have shown much improved EMI performance compared to the commercial graphite/wax ones. For further improvement of EMI shielding performance, split-press-merge approaches were applied to align the FLG fillers to achieve anisotropic characteristics in the plane perpendicular to the pressing direction. Much enhanced EMI shielding performance coupled with an improvement in absorption and reflection was observed in the post-alignment FLG/wax composites. An average interparticle distance model associated with improved electrically conducting interconnection and enlarged effective reflection regions with respect to enhanced reflection efficiency were discussed. The results suggest a platform and promising opportunities for preparing high-performance EMI shielding composites.

Ferroferric oxide/multiwalled carbon nanotube vs polyaniline/ferroferric oxide/multiwalled carbon nanotube multiheterostructures for highly effective microwave absorption.

Light-weight nanocomposites filled with carbon nanotubes (CNTs) are developed for their significant potentials in electromagnetic shielding and attenuation for wide applications in electronics, communication devices, and specific parts in aircrafts and vehicles. Specifically, the introduction of a second phase into/onto CNTs for achieving CNT-based heterostructures has been widely pursued due to the enhancement in either dielectric loss or magnetic loss. In this work, ferroferric oxide (Fe(3)O(4)) was selected as the phase in multiwalled carbon nanotube (MWCNT)-based composites for enhancing magnetic properties to obtain improved electromagnetic attenuation. A direct comparison between the two-phase heterostructures (Fe(3)O(4)/MWCNTs) and polyaniline (PANI) coated Fe(3)O(4)/MWCNTs, namely, three-phase heterostructures (PANI/Fe(3)O(4)/MWCNTs), was made to investigate the interface influences of Fe(3)O(4) and PANI on the complex permittivity and permeability separately. Compared to PANI/Fe(3)O(4)/MWCNTs, Fe(3)O(4)/MWCNTs exhibited enhanced magnetic properties coupled with increased dielectric properties. Interfaces between MWCNTs and heterostructures were found to play a role in the corresponding properties. The evaluation of microwave absorption of their wax composites was carried out, and the comparison between Fe(3)O(4)/MWCNTs and PANI/Fe(3)O(4)/MWCNTs with respect to highly efficient microwave absorption and effective absorption bandwidth was discussed.

Electronic scattering leads to anomalous thermal conductivity of n-type cubic silicon carbide in the high-temperature region.

This study simulates thermal conductivity via a carrier scattering mechanism and the related parameters are obtained based on first principles for intrinsic and doped silicon carbide (SiC) over a temperature range of 300-1450 K. The theoretical analysis results show that the thermal conductivity decreases with increasing temperature along each orientation for both cubic SiC (3C-SiC) and doped SiC. Compared with traditional calculations, the thermal conductivity of doped SiC is larger than that of intrinsic SiC in the high-temperature region. In particular, the n-type thermal conductivity is higher than the p-type thermal conductivity because of the scattering probability between electrons and the ionization impurity increasing with the temperature. Our studies are important to a further understanding of thermal transportation.