Carbon black-based conductive rubber composites have important impacts on electromagnetic interference(EMI) shielding applications. However, an excessive amount of carbon black in the recipes of ...these conductive rubbers has caused their weak elasticity. Herein, hollow carbon black(HCB) particles were used to tune the elasticity of conductive rubber composites. Unique hollow morphology produced a better compression recovery of HCB than other solid carbon black, such as acetylene black. When the coupling agent was bonded to HCB, their conductive silicone rubber composites were featured by high stretching resilience, a fast compression recovery and excellent conductivity to satisfy the electromagnetic interference shielding requirements. Importantly, the rubber composites with coupling HCB had extremely low variations of mechanical property, conductivity and EMI shielding effectiveness after thermal accelerated aging tests. It is therefore revealed that the elasticity of HCB and its interfacial chemical coupling with rubber chains both play crucial roles in adjusting the elasticity of conductive rubber to sever long-term EMI protection.
Few studies have been conducted on the crack propagation law and failure characteristics of coal-rock combined body (CRCB) with prefabricated fissure. A sliding crack model was firstly presented to ...analyze the failure law of rock with a single fracture and the influence of the inclination angle of the fracture on the strength of the rock. The RFPA numerical models of the CRCB with different inclination angles of prefabricated fracture were then established to simulate the dynamic change process of crack propagation and shear stress of the CRCB with prefabricated fracture under uniaxial compression. The influence of the inclination angle of the fracture in the rock on the fracture expansion and failure characteristics of CRCB was further analyzed based on the acoustic emission data. The results showed that (1) when 2β=arctan1/μ, σcw takes the minimum value, and crack initiation is most likely to occur; (2) the strength of coal-rock assemblage shows different changing trends with the fracture inclination angle; (3) the secondary cracks of CRCB with prefabricated fracture of 0°, 15°, and 30° initiated and expanded near the tip of the main crack, and the secondary cracks of 45°, 60°, and 75° initiated and expanded from the tip of the main crack; (4) there are three failure modes of CRCB with prefabricated crack, the double-shear failure mode Λ, the tensile-shear composite failure mode along the fracture surface, and the tensile failure mode along the fracture surface; and (5) intact CRCB and CRCB with prefabricated crack when α=75° and α=90° have strong brittleness, and other CRCB with different prefabricated fracture inclination angles show a certain degree of postpeak plasticity. The results on the mechanical properties and damage characteristics of CRCB are of great significance for the safety and efficient mining of deep coal resources.
Background: Most studies of allograft versus autograft for anterior cruciate ligament reconstruction have been of bone–patellar tendon–bone; outcome reports evaluating anterior cruciate ligament ...reconstruction with hamstring tendon autograft versus allograft are rare.
Purpose: This study was undertaken to compare the clinical outcome of arthroscopic anterior cruciate ligament reconstruction with hamstring tendon autograft versus allograft.
Study Design: Randomized controlled trial; Level of evidence, 2.
Methods: Between 2000 and 2004, 208 patients who met the inclusion and exclusion criteria of the study were prospectively randomized into autograft (n = 104) or allograft (n = 104) groups. All hamstring tendon allografts were fresh-frozen and obtained from a single certified tissue bank. All the operations were done by the same surgeon with the same surgical technique. Femoral and tibial fixation was by means of an EndoButton and a bioabsorbable interference screw augmented with a staple, respectively. Patients were evaluated preoperatively and postoperatively. Evaluations included detailed history, physical examination, functional knee ligament testing, KT-2000 arthrometer testing, Harner vertical jump and Daniel 1-legged hop tests, Lysholm score, Tegner score, the International Knee Documentation Committee (IKDC) standard evaluation form, Cincinnati knee score, and radiographs.
Results: Of these patients, 186 (autograft, n = 91; allograft, n = 95) were available for full evaluation. Demographic data were comparable between groups. The mean follow-up was 7.8 years for both groups. There were no statistically significant differences according to the evaluations of the outcome aforementioned between the 2 groups except that patients in the allograft group had a shorter operation time than the autograft group. Seven patients (7.7%) in the autograft group and 8 (8.4%) in the allograft group had a side-to-side difference >5 mm. Eighty-five patients (93.4%) in the autograft group and 86 (90.5%) in the allograft group were normal or nearly normal according to the overall IKDC. According to the subjective IKDC, the average scores were 89 and 90 points, respectively, for the autograft and allograft groups. The mean Lysholm and Tegner scores were 89 points and 7.7 points, respectively, for the autograft group and 90 points and 7.6 points, respectively, for the allograft group. For the Cincinnati knee score, the average scores were 90 and 91 points, respectively, for the autograft and allograft groups.
Conclusion: Both groups of patients achieved almost the same satisfactory outcome at an average of 7.8 years of follow-up. Fresh-frozen hamstring tendon allograft is a reasonable alternative choice to autograft for anterior cruciate ligament reconstruction.
Circular RNAs (circRNAs) play an important role in the occurrence and development of diseases. However, the role of circRNAs in male smokers with chronic obstructive pulmonary disease (COPD) remains ...unclear.BackgroundCircular RNAs (circRNAs) play an important role in the occurrence and development of diseases. However, the role of circRNAs in male smokers with chronic obstructive pulmonary disease (COPD) remains unclear.Stable COPD patients and healthy controls were recruited. Peripheral blood mononuclear cells (PBMCs) were extracted. After high-throughput RNA sequencing (RNA-Seq) of PBMCs, a bioinformatics method was used to analyse differentially expressed (DE) circRNAs (DEcircRNAs) and mRNAs (DEmRNAs).MethodsStable COPD patients and healthy controls were recruited. Peripheral blood mononuclear cells (PBMCs) were extracted. After high-throughput RNA sequencing (RNA-Seq) of PBMCs, a bioinformatics method was used to analyse differentially expressed (DE) circRNAs (DEcircRNAs) and mRNAs (DEmRNAs).Total of 114 DEcircRNAs and 58 DEmRNAs were identified. Functional enrichment analysis showed that processes related to COPD include the regulation of interleukin (IL)-18, IL-5 and the NLRP3 inflammasome; differentiation of T helper type 1 (Th1), Th2, and Th17 cells, and the AMPK, Wnt, JAK-STAT, and PI3K-Akt signalling pathways. In the protein-protein interaction (PPI) network, the core genes were MYO16, MYL4, SCN4A, NRCAM, HMCN1, MYOM2, and IQSEC3. Small-molecule prediction results revealed potential drugs for the COPD treatment. Additionally, the circRNA-miRNA-mRNA competitive endogenous RNA (ceRNA) regulatory network was constructed.ResultsTotal of 114 DEcircRNAs and 58 DEmRNAs were identified. Functional enrichment analysis showed that processes related to COPD include the regulation of interleukin (IL)-18, IL-5 and the NLRP3 inflammasome; differentiation of T helper type 1 (Th1), Th2, and Th17 cells, and the AMPK, Wnt, JAK-STAT, and PI3K-Akt signalling pathways. In the protein-protein interaction (PPI) network, the core genes were MYO16, MYL4, SCN4A, NRCAM, HMCN1, MYOM2, and IQSEC3. Small-molecule prediction results revealed potential drugs for the COPD treatment. Additionally, the circRNA-miRNA-mRNA competitive endogenous RNA (ceRNA) regulatory network was constructed.This study identified a set of dysregulated circRNAs and mRNAs and revealed potentially important genes, pathways, new small-molecule drugs and ceRNA regulatory networks in male smokers with COPD. These circRNAs might be prospective biomarkers or potential molecular targets of the ceRNA mechanism for COPD.ConclusionThis study identified a set of dysregulated circRNAs and mRNAs and revealed potentially important genes, pathways, new small-molecule drugs and ceRNA regulatory networks in male smokers with COPD. These circRNAs might be prospective biomarkers or potential molecular targets of the ceRNA mechanism for COPD.
Metasurfaces have been widely used to control beam propagation e.g. transmission, reflection, and absorption on an interface through a thin layer of nanoantennas with the thickness smaller than the ...wavelength. However, previous study of metasurfaces typically focused on controlling only one form of these propagations. In this work, we propose and demonstrate a multipolar plasmonic metasurface that can simultaneously realize antireflection (AR) and antitransmission (AT) in the visible and near-infrared regions. The AR and AT arise from destructive multipolar interferences in the backward and forward directions, respectively, i.e., through the generalized Kerker effect. By engineering the multipolar interference, we show that the AR and AT can happen at different or similar wavelength ranges, which can be used for low-absorption spectral filters due to off-resonance operation or inversely strong optical absorbers through near-resonance operation, respectively. We also present a simple two-dimensional design of the multipolar metasurface that supports AT for one polarization and AR for another polarization over a broadband, which is applicable to broadband transmissive polarizers with efficiency over 90% and the extinction ratio over 18 dB. By tuning the dimension and thus the multipolar interference, the transmitted polarization and operation wavelength are both controllable.
Sum frequency generation (SFG) has multiple applications, from optical sources to imaging, where efficient conversion requires either long interaction distances or large field concentrations in a ...quadratic nonlinear material. Metasurfaces provide an essential avenue to enhanced SFG due to resonance with extreme field enhancements with an integrated ultrathin platform. In this work, we formulate a general theoretical framework for multi-objective topology optimization of nanopatterned metasurfaces that facilitate high-efficiency SFG and simultaneously select the emitted direction and tailor the metasurface polarization response. Based on this framework, we present novel metasurface designs showcasing ultimate flexibility in transforming the outgoing nonlinearly generated light for applications spanning from imaging to polarimetry. For example, one of our metasurfaces produces highly polarized and directional SFG emission with an efficiency of over 0.2 cm
GW
in a 10 nm signal operating bandwidth.
Detailed experimental studies of the dynamics of self-trapped beams of white light (400−800 nm) in a photosensitive organosiloxane medium are presented. Self-trapped white light beams with similar ...spatial profiles formed in the organosiloxane at intensities ranging across an order of magnitude (2.7−22.0 W·cm-2). Beam-profiling measurements showed that these spatially and temporally incoherent wave packets propagate without diffracting (broadening) by initiating free-radical polymerization of methacrylate groups and corresponding refractive index changes in the organosiloxane medium. Analyses of their temporal evolution showed that the intensity-dependent behavior of self-trapped white light is similar to that of self-trapped laser light despite the extreme differences in their phase structure and chromaticity; the self-trapped incoherent beams even show the complementary oscillations of width and intensity that is characteristic of self-trapped coherent light. Furthermore, the dynamics of the self-trapped white light beams was found to be strongly correlated to the kinetics of free-radical polymerization and corresponding rates of refractive index changes in the organosiloxane. These studies provide accessible photochemical routes to self-trapped incoherent wave packets, which are extremely difficult to generate in conventional nonlinear optical media that owe their responses to higher-order dielectric susceptibility tensors. This could enable the experimental verification of theoretical models developed for the nonlinear propagation of white light and stimulate research into more complex self-trapping phenomena such as the interactions of self-trapped incoherent beams and spontaneous pattern formation due to modulation instability in a uniform incoherent optical field. These findings also carry potential for the development of self-induced waveguide, optical solder and interconnect technology for incoherent light emitted by incandescent sources or LEDs.
To address the large deformation of the surrounding rock of deep gob-side entry retaining under high stress, lithological characteristics of the surrounding rock and failure model of support body and ...their evolutionary processes are analyzed through field investigation and theoretical analysis. Failure mechanisms of surrounding rock and the technology to control it are studied systematically. The results show that the causes of the large deformation of the surrounding rock are weak thick mudstones with softening property and water absorption behavior, as well as its fragmentation, dilatancy, and long-term creep during strong disturbance and highly centralized stress states. The cross-section shape of the roadway after deformation and failure of the surrounding rock is obviously asymmetric in both the horizontal and vertical directions. Since the original system supporting the surrounding rock is unable to completely bear the load, each part of the supporting system is destroyed one after the other. The failure sequences of the surrounding rock are as follows: (1) roadway roof fracture in the filling area, (2) filling body fracture under eccentric load, (3) rapid subsidence of the roadway roof, and (4) external crack drum and rib spalling at the solid coal side. Due to this failure sequence, the entire surrounding rock becomes unstable. A partitioned coupling support and a quaternity control technology to support the surrounding rock are proposed, in which the roof of the filling area plays a key role. The technology can improve the overall stability of gob-side entry retaining, prevent support structure instability caused by local failure of the surrounding rock, and ensure the safety and smoothness of roadways.
Bismuth-based cubic pyrochlore thin films, such as Bi1.5ZnNb1.5O7 (BZN) and Bi1.5MgNb1.5O7 (BMN) thin films show attractive properties for microwave tunable system due to their medium dielectric ...constant, low dielectric loss, and high dielectric tunability. Several deposition technologies are used for preparing bismuth-based cubic pryochlore thin films. The effects of different thin film deposition approaches on the structure and dielectric properties of BZN/BMN thin films are summarized. The advantages and limitations of bismuth-based cubic pyrochlore thin films deposited by different deposition technologies are also discussed from the viewpoint of dielectric properties.
Ring-opening metathesis polymerization of a series of 3-substituted cyclooctenes (3-MeCOE, 3-HexCOE, and 3-PhCOE) initiated by various Mo and W MAP complexes leads to cis,HT-poly(3-RCOE) polymers. ...The apparent rate of polymerization of 3-HexCOE by W(N-t-Bu)(CH-t-Bu)(Pyr)(OHMT) (1c; Pyr = pyrrolide; OHMT = O-2,6-Mesityl2C6H3) is greater than the rate of polymerization by Mo(N-t-Bu)(CH-t-Bu)(Pyr)(OHMT) (1b), but both gave the same cis,HT polymer structures. Formation of HT-poly(3-RCOE) employing 1c takes place via propagating species in which the R group (methyl, hexyl, or phenyl) is on C2 of the propagating alkylidene chain, a type of intermediate that has been modeled through the preparation of W(N-t-Bu)(CHCHMeEt)(Pyr)(OHMT). The rate of ROMP is exceedingly sensitive to steric factors: e.g., W(N-t-Bu)(CH-t-Bu)(Me2Pyr)(OHMT), the dimethylpyrrolide analogue of 1c, essentially did not polymerize 3-HexCOE at 22 °C. When a sample of W(N-t-Bu)(CHCHMeEt)(Pyr)(OHMT) and 3-methyl-1-pentene in CDCl3 is cooled to −20 °C, the alkylidene resonances for W(N-t-Bu)(CHCHMeEt)(Pyr)(OHMT) disappear and resonances that can be ascribed to protons in a syn α /syn α′ disubstituted trigonal bipyramidal metallacyclobutane complex appear. 3-Methyl-1-pentene is readily lost from this metallacycle on the NMR time scale at room temperature.
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