Bridging Effect Research Articles

Pencil drawn meter bridge

Abstract This study investigates the application of a Wheatstone bridge, specifically through the utilization of a meter bridge constructed on chart paper using pencil graphite. Employing the Wheatstone bridge principle, this study aims to achieve precise measurements of an unknown resistance. Results indicate an error margin between measured and calculated values of less than 10%, highlighting the efficiency and accuracy of this approach. The demonstrated effectiveness of the meter bridge serves as an educational resource, particularly beneficial for K-12 students, providing practical understanding and hands-on experience with the meter bridge concept. This research contributes to enhancing STEAM education by offering a tangible and accessible tool for teaching electrical circuit principles.

TiO2-loaded phosphogypsum-modified biochar for the removal of ofloxacin and Cu2+: Performance, mechanisms, and toxicity assessment

The combined contamination of antibiotics and heavy metals usually occurs in aquaculture wastewater and has high ecological toxicity. Currently, most research only focuses on the removal of a single heavy metal or antibiotics, and there is little research on the simultaneous removal of both. Therefore, to effectively treat them, this study prepared TiO2-loaded phosphogypsum-modified biochar (TYBC450) for adsorption and photocatalytic removal of ofloxacin (OFL) and copper (Cu2+). The removal performance and mechanisms of OFL and Cu2+ were explored, and their ecological toxicity was assessed through zebrafish acute toxicity experiments. The results suggested a synergistic effect between OFL and Cu2+. The adsorption efficiencies of TYBC450 for OFL and Cu2+ were 88.16% and 90.87% (the adsorption capacities were 1.75 and 3.65 mg/g, respectively). Bridging, precipitation, and complexation effects were the main co-adsorption mechanisms. The photocatalytic efficiencies of OFL and Cu2+ were 91.23% and 72.09% (the rate constants were 0.0101 and 0.0045 min-1, respectively). OFL acted as a hole-trapping agent, while Cu2+ acted as an electron acceptor, hindering the combination of e- and h+. There were 12 intermediates in the OFL degradation process, which had lower toxicity than the mother organism. Both the cyclic regeneration and actual aquaculture wastewater application tests indicated that TYBC450 had potential application prospects.

Molecular modeling to elucidate the dynamic interaction process and aggregation mechanism between natural organic matters and nanoplastics

The interactions of nanoplastics (NPs) with natural organic materials (NOMs) dominate the environmental fate of both substances and the organic carbon cycle. Their binding and aggregation mechanisms at the molecular level remain elusive due to the high structural complexity of NOMs and aged NPs. Molecular modeling was used to understand the detailed dynamic interaction mechanism between NOMs and NPs. Advanced humic acid models were used, and three types of NPs, i.e., polyethylene (PE), polyvinyl chloride (PVC), and polystyrene (PS), were investigated. Molecular dynamics (MD) simulations revealed the geometrical change of the spontaneous formation of NOMs-NPs supramolecular assemblies. The results showed that pristine NPs initially tend to aggregate homogeneously due to their hydrophobic nature, and then NOM fragments are bound to the formed NP aggregates mainly by vdW interaction. Homo- and hetero-aggregation between NOMs and aged NPs occur simultaneously through various mechanisms, including intermolecular forces and Ca2+ bridging effect, eventually resulting in a mixture of supramolecular structures. Density functional theory calculations were employed to characterize the surface properties and reactivity of the NP monomers. The molecular polarity indices for unaged PE, PS, and PVC were 3.1, 8.5, and 22.2 ​kcal/mol, respectively, which increased to 43.2, 51.6, and 42.2 ​kcal/mol for aged NPs, respectively, indicating the increase in polarity after aging. The vdW and electrostatic potentials of NP monomers were visualized. These results clarified the fundamental aggregation processes, and mechanisms between NPs and NOMs, providing a complete molecular picture of the interactions of nanoparticles in the natural aquatic environment.

Investigation of machining performance of waspaloy using copper-graphite composite electrodes in electric discharge machining

Abstract This study endeavoured to investigate the machining of Waspaloy using Electric Discharge Machining (EDM), utilizing copper-graphite composites as the tool material. Given the limited existing research on machining Waspaloy with composite tools, this study aims to address this gap by employing a copper-graphite composite tool. In this work, pure copper electrode and three composite electrodes with varying graphite percentages in copper, viz. copper containing 5%, 10%, and 15% graphite (CuGr-5, CuGr-10, and CuGr-15), are utilized for experimentation. Composite electrodes are fabricated by the stir-casting process. The scanning electron microscope reveals that the graphite specks are homogeneously disseminated over the matrix material. The Taguchi mixed orthogonal array was used for developing experimental runs. By varying the current, polarity, pulse on and off times, tool materials, and gap, machining performance was measured in terms of Material Removal Rate (MRR), Tool Wear Rate (TWR), and Surface Roughness (Ra). It was observed that CuGr-5 provides an enhancement in MRR due to the improved electric conductivity, bridging effect, and increased energy concentration at the spark gap. Diverse characteristics witnessed on the surface morphology include black dots, globules, remelted layers, micro-cracks, and scratches. When machined with a CuGr5 electrode, the surface quality improved owing to the completed flushing and uniform distribution of generated heat as confirmed through worn surface morphology. The parameters were optimized utilizing the PROMETHEE optimization technique; it was found that the CuGr-5 electrode with the assessment value 0.02458 was optimal for machining of Waspaloy.

Enhancing interlaminar fracture toughness and shear strength of carbon fiber composite laminates via orientation of nickel-plated short carbon fibers in a magnetic field

This study aimed to enhance the interlaminar mechanical properties of carbon fiber composites by incorporating nickel-plated short carbon fibers (Ni@SCFs) between adjacent layers in a magnetic field. Herein, non-flocked composites, flocked composites with unoriented Ni@SCFs, and flocked composites with oriented Ni@SCFs using a magnetic field were fabricated to investigate the impact of fiber orientation on the mode I interlaminar fracture toughness (GIC) and interlaminar shear strength (ILSS) of the composite laminates. It was observed that Ni@SCFs were distributed at varying vertical angles between adjacent layers under the influence of the magnetic field. The areal density of oriented Ni@SCFs was systematically increased, resulting in notable enhancements in both initiation and propagation of GIC for flocked composites. At a flocking density of 6 g/m2, maximum values reached 533 J/m2 and 769 J/m2 respectively, representing a substantial increase of 52 % and 63 % compared to non-flocked composites. Additionally, the ILSS of flocked composites with oriented Ni@SCFs significantly improved to 55.83 MPa at a flocking density of 2 g/m2, indicating an increase of 27 % over non-flocked composites. The oriented Ni@SCFs played a crucial role in inhibiting crack propagation through the fiber bridging effect.

Enhancing EMI learning through L1 use and ESP: A mixed-methods study in a Chinese transnational education context

This paper employs a mixed-methods design to investigate the supportive roles of the translanguaging practice, specifically the use of students' First Language (L1), and English for Specific Purposes (ESP) courses within the context of English Medium Instruction (EMI) in a Transnational Education (TNE) program in China. It involved collecting questionnaire responses from 268 undergraduate Chemical Engineering students and conducting 17 follow-up semi-structured interviews. The hierarchical multiple regression analysis revealed students' academic language-related challenges and ESP course performance were two statistically significant predictors of their EMI academic success; academic linguistic challenges and students' L1 use attitudes emerged as significant indicators of their EMI learning self-efficacy. Qualitative data analysis further uncovered students' positive beliefs regarding the bridging effects of L1 use on facilitating their EMI learning and the foundational role of ESP courses in linguistic preparation. These empirical findings lead to significant pedagogical implications, aiming to scaffold effective EMI learning in the investigated context.

Experimental and numerical buckling analysis of CNT reinforced polymer composite plates

A combined experimental and numerical buckling analysis is performed for Carbon nanotube-reinforced composite (CNTRC) laminates under uniaxial in-plane compressive load. A finite element simulation program is developed in MATLAB environment and the recorded buckling responses are verified with the experimental results. Closely aligned numerical and experimental results exhibits that inclusion of 0.3% CNT increases buckling strengths of CNTRC composite laminates, regardless of their geometrical parameters. Clamped edge laminates exhibit higher buckling mode shapes, influenced by aspect ratio and edge restraint. Microscopic analysis of CNTRC's fractured surface under compression shows enhanced buckling strength attributed to CNTs’ bridging and pullout effects in the matrix, suppressing crack initiation and propagation. Field Emission Scanning Electronic Microscope (FESEM) is utilized for this investigation.

Unification of thermal conductivity, electrical insulation, and electromagnetic shielding: A bulk thermal conductive polymer from solid waste

In the context of the ongoing advancements in high-performance chips, heat dissipation, and electromagnetic shielding within electrical and electronic equipment are becoming increasingly intricate. Plastics have garnered widespread usage in electrical and electronic equipment as prevalent framework materials. However, the challenge persists in achieving a unification of electromagnetic interference (EMI) shielding, thermal conductivity (TC), and electrical insulation performance for plastics. Herein, we capitalize on the styrene–butadiene–styrene (SBS) copolymer to integrate the merits of polymers and magnetic minerals. Utilizing pyrrhotite (Pyr) tailings and waste polystyrene (PS) as raw materials, a formable block material denoted as PS-S@SBS/Pyr has been formulated. This material exhibits commendable performance in terms of TC, electrical insulation, and EMI shielding performance concurrently. The bidirectional bridging effect of SBS effectively reduces the interfacial thermal resistance between PS and Pyr. The TC of PS-S@SBS/Pyr can reach a maximum of 1.36 W/m‧K with a resistivity greater than 108 Ω‧m. Moreover, PS-S@SBS/Pyr consistently demonstrates a stable EMI shielding effectiveness of 33.1 dB within the 8–12 GHz frequency range, with absorption shielding predominating as the underlying mechanism. This green preparation method makes efficient utilization of two main solid wastes while increasing the added value of the material.

Synthesis of suspension stabilizers for isolation fluids by response surface methodology and study of their properties

In order to solve the problem of unstable settling of isolation fluid at high temperatures, high-temperature-resistant suspension stabilizers for isolation fluids were prepared. Using the free radical aqueous solution method with 2-acrylamido-2-methylpropanesulfonic acid (AMPS), YX-1 (a monomer containing an amide group) as the main chain of the molecule, and N-Vinylpyrrolidone (NVP) and DX-2 (monomer containing hydrophobic groups) as the side chains of the molecule. We innovate the suspension stabilizer synthesis process, the synthesis conditions of the suspension stabilizer were optimized by using the one-factor experimental design and response surface analysis. The elemental composition and structure of the polymer suspension stabilizers were tested and analyzed by using X-ray spectroscopy (XPS), infrared spectroscopy (FTIR) and nuclear magnetic resonance hydrogen spectroscopy (H NMR). The hydrophobic aggregation behaviour of the polymer molecular chains was demonstrated from a microscopic point of view using fluorescence spectroscopy tests and size analysis of polymer molecular aggregates. Oscillation experiments on the isolation solution with suspension stabiliser showed that the hydrophobic groups contained in the polymers can undergo the effect of joining and bridging, and can also form a strong spatial network structure at 220°C, leading to the enhanced elasticity of the isolation fluid, which helps to alleviate the sedimentation of barite. Sedimentation stability and compatibility were evaluated for the isolation fluid containing suspension stabilizers. It was found that the isolation solution suspension performance is good under the condition of 90–220℃, its density difference is less than 0.10 g/cm3. It can also effectively prevent the contact contamination of the drilling fluid cement slurry, which is conducive to the improvement of the quality of the deep well cementing.

Enhanced interface bonding of hydrophobic encapsulated hydrogel fibers by mechanical interlocking structure: Toward anti-drying and anti-swelling strain sensors

Conductive hydrogel fibers with superior mechanical and electrical performance have been developed for flexible wearable electronics, but the inherent properties of hydrogels for dehydration in the atmosphere and underwater swelling limit its widespread application. In this work, a silicone rubber encapsulated hydrogel fiber with enhanced interface bonding, excellent mechanical and electrical properties was successfully developed, in which the core polyvinyl alcohol/sodium alginate hydrogel fiber was prepared by a continuous wet-spinning and the following freeze-thawing. The interlocking dual-network structure and the improved ion transport by negatively charged sodium alginate gave the core hydrogel fiber excellent strength of 4.15 MPa, elongation-at-break of 1531 % and electrical conductivity of 17.01 S·m−1. After encapsulation using a silicone rubber, the composite hydrogel fiber showed a low expansion rate underwater for 7 days of 1.00 ± 0.21 % and low weight loss in the air over 36 h of 38.67 ± 0.38 %. And the interface bonding of the core hydrogel fiber and silicone layer was enhanced by the bridging effect of amphiphilic stearic acid. Therefore, the composite hydrogel fiber demonstrated a great potential as a strain sensor for underwater communication to ensure the safety of individuals in an underwater environment.

The analysis for fatigue caused by vibration of railway composite beam considering time-dependent effect

The time-dependent effects in steel-concrete composite beam bridges can intensify track irregularities, subsequently leading to amplified train-bridge coupling vibrations. This phenomenon may increase the stress amplitudes in the bridge steel, thereby impacting the fatigue performance of the composite structures. This paper employs multiple rigid body dynamics to construct a high-speed train model and utilizes the finite element method to develop a steel-concrete composite beam element model that accounts for time-dependent effects, interfacial slip, and shear hysteresis. This approach enables the computational analysis of the train-bridge coupling system, facilitating an investigation into the influence of concrete’s time-dependent effects on the fatigue performance of railway steel-concrete composite bridges. Focusing on a 40-m simply supported composite bridge, the train-bridge coupling dynamic responses were computed for each operational year within a decade of the completion of construction. Applying the P-M linear fatigue damage accumulation theory, statistical analysis of stress history data across various operational periods was conducted to quantify the fatigue damage induced by a single eight-car high-speed train on the lower flange of the mid-span steel beam and the beam-end studs. The findings reveal that the beam-end studs sustain greater damage than the mid-span steel beam. Moreover, the detrimental impact of time-dependent effects diminishes with the increase of operational years. Notably, compared to the initial year, the fatigue damage to the lower flange of the mid-span steel beam by an eight-car train in the tenth year has surged by 39.3%. Conversely, the damage to the beam-end studs has decreased by 47.5%.

Changes in the Aggregation Behaviour of Zinc Oxide Nanoparticles Influenced by Perfluorooctanoic Acid, Salts, and Humic Acid in Simulated Waters.

The increasing utilization of zinc oxide nanoparticles (ZnO-NPs) in many consumer products is of concern due to their eventual release into the natural environment and induction of potentially adverse impacts. The behaviour and environmental impacts of ZnO-NPs could be altered through their interactions with environmentally coexisting substances. This study investigated the changes in the behaviour of ZnO-NPs in the presence of coexisting organic pollutants (such as perfluorooctanoic acid [PFOA]), natural organic substances (i.e., humic acid [HA]), and electrolytes (i.e., NaCl and CaCl2) in simulated waters. The size, shape, purity, crystallinity, and surface charge of the ZnO-NPs in simulated water after different interaction intervals (such as 1 day, 1 week, 2 weeks, and 3 weeks) at a controlled pH of 7 were examined using various characterization techniques. The results indicated alterations in the size (such as 162.4 nm, 1 day interaction to >10 µm, 3 weeks interaction) and zeta potential (such as -47.2 mV, 1 day interaction to -0.2 mV, 3 weeks interaction) of the ZnO-NPs alone and when PFOA, electrolytes, and HA were present in the suspension. Different influences on the size and surface charge of the nanoparticles were observed for fixed concentrations (5 mM) of the different electrolytes. The presence of HA-dispersed ZnO-NPs affected the zeta potential. Such dispersal effects were also observed in the presence of both PFOA and salts due to their large aliphatic carbon content and complex structure. Cation bridging effects, hydrophobic interactions, hydrogen bonding, electrostatic interactions, and van der Waals forces could be potential interaction forces responsible for the adsorption of PFOA. The presence of organic pollutants (PFOA) and natural organic substances (HA) can transform the surface characteristics and fate of ZnO-NPs in natural and sea waters.

Coadsorption mechanisms of copper and sulfamethoxazole by functionalized cellulose: A kinetic and DFT study

In order to address the issue of compound pollution from heavy metals and antibiotics in aquatic environments, multibranched functionalized cellulose materials (DACS) with abundant adsorption affinity groups (such as amino, carboxyl and imine groups) were prepared by oxidation, etherification and grafting. The maximum adsorption capacities of DACS for copper (Cu) and sulfamethoxazole (SMZ) were 42.27 and 117.92 mg/g, respectively. In addition, its excellent pH buffering capacity, resistance to coexisting interfering substances and great regeneration performance of up to 91 % after 5 cycles. In the coadsorption experiment, the multibranched structure strengthened the bridge effect during the coadsorption process, and weakened the inhibition of SMZ adsorption caused by competition. Kinetic models and error functions analysis showed that PNO model and F&S model were the most consistent with the adsorption process, and the limiting step of adsorption was the external diffusion of Cu and SMZ around the surface of DACS. Moreover, the density functional theory (DFT) was used to quantitatively calculate the adsorption binding energy of multiple sites on DACS, and clarified the adsorption tendency of DACS as electron donors for Cu and as acceptor for SMZ. In addition, the binding energy of sequential adsorption was greater than that of single and binary adsorption, and the binding stability of SMZ was significantly increased in sequential adsorption for the increasing of binding energy. The electron exchange process in the adsorption showed that SMZ played a bridging role in the binary adsorption, while Cu was the main reaction part of the complex adsorption.

Microstructure evolution and mechanical behavior of foamed cement-based tail backfills under varying fiber types and concentrations.

Industrial solid waste (mine tailings) management has emerged as the key universal ecological challenge as a result of the unceasing creation of rising waste by-products. Employing tailings makes mine fill production economical and assists resolve disposal problems. Foamed cement-based tailings backfill (FCTB) is a mine fill consisting of tailing, cement, water, and foaming agents. It provides certain advantages such as lightweight, good fluidity, and thermal insulation yet is relatively weak in strength. Additionally, FCTB's strength properties can be intensely improved by adding fibers. A total of three diverse fibers: polypropylene (PP), glass (G), and basalt (B) as well as dodecyltrimethylammonium bromide (DTAB) as a foaming agent were used to prepare fiber-reinforced foamed cementitious tailings backfill (FR-FCTB). The mechanical properties, energy evolution, ductility, and microstructure of FR-FCTB were elaborately investigated by uniaxial compression tests (UCS) and SEM. Laboratory findings demonstrate the reinforcing effect of three fibers on FCTB specimens: glass > polypropylene > basalt. FR-FCTB showed the best strength features as a fiber content of 0.3% was adopted in FCTB. At this time, the UCS performance of glass fiber-reinforced FCTBs was 0.85MPa increased by 18.1%. The addition of fibers can increase the fill's energy storage limit, slow down the discharge of elastic strain energy within the backfill, and enhance the fill's ductility and toughness. The ductility factor evaluates the degree of deterioration of filling in terms of post-peak drop, with all FR-FCTB values being greater than CTB. FR-FCTB's chief hydration product is the C-S-H gel. Fiber's bridging effect significantly rallies crack extension and thus fill's strength features. Lastly, the study's main results are instructive for the industrial application of FR-FCTB used in metallic mines.

Hybrid fiber reinforced ultra-high performance coal gangue geopolymer concrete (UHPGC): Mechanical properties, enhancement mechanism, carbon emission and economic analysis

The low carbonization of ultra-high performance concrete (UHPC) has become a hot topic for sustainable development in the construction industry. Calcined coal gangue was used as aggregate and binder to prepare ultra-high performance coal gangue geopolymer concrete (UHPGC) in this paper. The hybrid reinforcement effect of steel fibers, calcium carbonate whiskers (CW), and carbon nanotubes (CNTs) on UHPGC was studied in the experiment. The results indicated that when the mixing ratio of straight steel fibers and hooked-end steel fibers was 2:1, the 28 d-compressive strength of UHPGC reached 145.94 MPa. However, excessive hooked-end steel fibers deteriorated the reinforcement effect of adjacent fibers and reduced the mechanical properties of UHPGC. CW and CNTs had a more significant improvement in the flexural properties of UHPGC. The bridging effect of CNTs and CW dispersed the stress on the matrix and delayed the formation and development of micro-nano cracks. Meanwhile, CNTs and CW improved the fiber bridging energy dissipation, thereby improving the flexural properties of UHPGC. The UHPGC had the highest flexural strength and flexural deflection of 13.59 MPa and 4.12 mm, respectively. The UHPGC prepared in this paper had lower carbon emissions and economic costs compared to traditional UHPC. Overall, this study provided valuable references for the resource utilization of coal gangue and the multi-scale strengthening and toughening of UHPGC.

Study on High-Ductility Geopolymer Concrete: The Influence of Oven Heat Curing Conditions on Mechanical Properties and Microstructural Development.

Low carbon and high performance have become key trends in the development of construction materials. Understanding the mechanism by which curing conditions affect the mechanical properties of high-ductility geopolymer concrete (HDGC) is of significant importance. This study investigated three sealing curing temperatures (room temperature, 45 °C, and 60 °C) and four curing durations (1 day, 3 days, 5 days, and 7 days), while considering two final curing ages (7 days and 28 days) to explore their effects on the axial tensile and compressive properties of HDGC. The results showed that both 45 °C and 60 °C could improve the brittle failure of HDGC under axial compressive loading. However, curing at 60 °C and for durations longer than 1 day in an oven would catalyze the formation of eight-faced zeolite crystals within the slag-fly ash geopolymer matrix, and it could weaken the matrix's pore structure and subsequently affect the material's later strength development. Nevertheless, oven heat curing enhanced the bridging effect between the fibers and the matrix, partially compensating for the reduction in the initial tensile strength of HDGC. This follows the pseudo-strain-hardening material's saturation cracking criterion to enhance the strain-hardening behavior of HDGC and improve its tensile energy absorption capacity. A curing condition of 45 °C for 5 days is recommended to maximize the ductility of HDGC. This study provides important theoretical support for the design and promotion of green, low-carbon, high-ductility composite materials.

Unusual Electrical Conductivity Enhancement in Stable n-Type Carbon Nanotube Networks.

Organic molecule-doped n-type single-walled carbon nanotube (SWCNT) networks are promising candidates for advanced energy applications, such as flexible thermoelectrics and photovoltaics. Yet charge transport in n-type SWCNTs is limited by two factors: i) charge localization impeding inter-tube transport caused by disordered mesostructure of randomly oriented SWCNTs and ii) reduction of charge carrier concentration driven by oxidation. Herein, studied the relationship between the mesostructure and thermoelectric properties of n-type SWCNTs obtained by surfactant-functionalization and polymer-dopant grafting. Surprisingly, the electrical conductivity of the polymer-doped SWCNTs keeps increasing with increasing polymer content, even after the saturation of carrier concentration, resulting in 12x higher conductivity on polymer-doping compared to surfactant-functionalization. While hopping transport typically dominates in disordered systems, it is shown that a bridging effect from the polymer causes unusual band-like conduction in polymer-doped SWCNTs. Additionally, since surfactants are essential to prevent oxidation and retain n-type over a long duration, shows that SWCNTs obtained through a dual-functionalization strategy using both polymer-dopant and surfactant, demonstrates a long-term stable high n-type thermoelectric power factor, when the surfactant amount is carefully controlled. Besides thermoelectrics, the findings are of general interest to developing stable and conductive n-type SWCNTs for various energy and electronic applications.

Development of self-sensing cement composites by incorporating hybrid biochar and nano carbon black

The self-sensing cement composites (SSCC) containing traditional conductive carbon materials are of great significance but cause serious pollution. In this study, the green SSCC is innovatively developed utilizing the synergistic effects of nano carbon black and biochar from coconut shell. The SSCC mixtures are compared in terms of fluidity, mechanical properties, resistivity, microstructure and comprehensive properties. The results indicate that in SSCC containing nano carbon black, the addition of biochar can obtain comparable compressive strength for its internal curing, interlocking and bridging effects. Besides, 4.5 % carbon material prolongs the crack initiation stage during compression, and 9 % carbon material causes the multiple cracks. Moreover, the addition of 4.5 % biochar can reduce the 35-day resistivity of sample with 1.5 % biochar and 3 % nano carbon black by 35.6 % owing to the increasing tunneling effect and contact conduction. It is also found that in conductive SSCC, the slope Kc of the non-contact resistivity curve is dominated by the conductive additives rather than cement hydration. And the self-sensing cement composites exhibit excellent piezoresistivity. The rates of change in resistivity of samples after cycle loading are exponentially related to residual damages, with R2 values greater than 0.95. Finally, multi-indicator evaluation analyses show that the sample containing more biochar is more environmentally friendly. This study provides a new pathway for the sustainable development of SSCC.

Myocardial ischemia caused by the synergistic effect of myocardial bridge and moderate stenosis: case report

BackgroundClinical events such as angina pectoris, acute coronary syndrome, and sudden death caused by myocardial bridge (MB) have attracted increasing attention. It is still a challenge to diagnose whether MB can cause the symptoms of patients with MB. For most MB patients, medication remains the primary treatment.Case presentationThis article reports a case of chest pain in a patient with MB in the middle segment of the left anterior descending artery (LADm) with moderate stenosis in the proximal segment (LADp). Through functional assessment, we found that neither MB nor fixed stenosis had sufficient effect on coronary blood flow to cause myocardial ischemia, but their synergistic effect resulted in myocardial ischemia. Finally, a stent was implanted in LADp and good clinical results were achieved.ConclusionsFor symptomatic patients with MB combined with fixed stenosis, functional evaluation may be necessary, which has significant guiding significance for treatment strategy selection. For asymptomatic patients, early detection of myocardial ischemia may also improve the prognosis of patients.

Improved thermal conductivity of high‐density polyethylene by incorporating hybrid fillers of copper powders and silicon carbide whiskers

AbstractIn this paper, highly electrically and thermally conductive copper powders (Cu) and electrically insulative yet thermally conductive silicon carbide whiskers (SiCw) were selected as functional fillers and high‐density polyethylene (HDPE) was used as the matrix to prepare thermal conductive composites. By controlling the amount of Cu at 30 vol% which is below percolation threshold, the volume resistivity of the composites is maintained above 1014 Ω cm. The results showed that SiCws entered the area which was not occupied by Cu particles and they played a bridging effect among Cu particles, thereby promoting the formation of intact thermal conductive pathways that contributed to improving the thermal conductivity of corresponding composites. The combination of SiCw:Cu = 3:1 at a filler content of 30 vol% resulted in a thermal conductivity as high as 1.921 W/mK, which is 380% higher than pure HDPE.