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The paper proposes a temperature-compensated sensor for microfluidic application. The sensor consists of a splitter/combiner section with two symmetrical complementary split-ring resonators (CSRR). A polydimethylsiloxane substrate is attached with the microfluidic channel aligned to the meander slot of the CSRR. A split-ring resonator (SRR) with peripheral circuit is added to detect environmental temperature. The water-methanol mixtures with various water fractions are measured at temperature ranging from 20°C to 50°C. The environmental temperature is firstly measured by the resonant frequency shift produced by SRR. Then, the variations in the resonant frequency and quality factor of the differential splitter/combiner section, as well as the temperature, are used as the input data for training the neural network. In comparison with previous designs, the proposed sensor is capable of not only suppressing the influences of environmental factors, but also retrieving the permittivity and loss tangent of liquid sample at specific temperature, thereby identifying the liquid accurately.

The paper proposes an ultrahigh sensitivity microwave sensor for retrieving the complex permittivity of the liquid sample. The proposed sensor originally evolves from the complementary split-ring resonator-based sensor, which confines the electric field in the slot of the resonator. A complementary electric-LC resonator structure is applied to substitute the CSRR due to its excellent ability of concentrating the electric field. To further improve the field confinement, a meander slot is embedded in the central arm of the resonator. Then, two etched complementary split-ring resonators are added on both sides of the central meander arm of the modified complementary electric-LC resonator. A polydimethylsiloxane microfluidic channel substrate is placed on the meander arm, and a mixture of water-ethanol is injected. The variations in the resonant frequency and peak attenuation are used to retrieve the complex permittivity of the injected liquid sample. The developed sensors are fabricated and tested, and a good agreement is observed between measured data and reference values. The peak sensitivities in retrieving the relative permittivity achieve 2.5% and 2.71% with the proposed sensors, which are much higher than previously reported designs.

The essence of the hydraulic fracturing method for enhancing oil recovery is described. The definition of proppants is given and their average chemical composition is determined. In the process of an analytical review, the article presents proppants that are widely used in the oil industry. For each type of proppant, the main technical characteristics (bulk density and compressive strength) required when using the hydraulic fracturing method have been determined. In the course of the analysis, it was found that all proppant technologies are expensive and it is necessary to select high-quality cheap and affordable materials to reduce the cost of their production. Drilling cuttings from the Morozovskoye field were chosen as one of these materials. Physical and chemical studies of drill cuttings were carried out, on the basis of which a conclusion was made about the possibility of its use in the synthesis of high-quality aluminosilicate proppants.

Cr1-xAlxN/CrN/Cr multilayer films with a range of different Al contents were deposited on 9–12% Cr heat-resistant steel using direct current magnetron sputtering (DCMS). The chemical composition, roughness, cross-sectional structure, oxidation resistance and kinetic model of oxidation of the resulting films were investigated using various techniques. We discovered that Al atoms substituted for Cr atoms, while the crystal structure remained unchanged. Since Al doping decreases the lattice constants and hinders grain growth, the roughness of the film decreases, and the microstructure becomes denser, which is beneficial to the enhancement of oxidation resistance. According to the kinetic model, internal diffusion is the main restrictive step in this process. Increasing the Al content aids in the formation of an amorphous oxide surface layer that is abundant in Al. When the Al content is sufficiently high, the diffusion of oxygen into the 9–12% Cr steel substrates is prevented by the oxide surface layer of the film, which protects the substrates from further oxidation.

In this study, the mechanical model of the circumferentially distributed rods and the nonlinear contact stiffness matrix which characterizes the contact effect between the disks are established. The contact stiffness matrix is composed of seven stiffness coefficients that characterize the lateral stiffness, shear stiffness, bending stiffness, and torsional stiffness of the contact interface. Then the influence of pre-tightening load, rod diameter, contact surface roughness, deformation phase and uneven pre-tightening load on stiffness coefficients is analyzed. Finally, combined with the experimentally verified nonlinear oil film force model based on short bearing theory, the dynamic model of the rod-fastening rotor-bearing system is established. By means of spectrum cascades and Campbell diagrams, the influence of the pre-tightening load, rod diameter, contact surface roughness and uneven pre-tightening load on the nonlinear dynamic characteristics of the rod-fastening rotor-bearing system is numerically analyzed. The results show that increasing the pre-tightening load can increase the contact stiffness, and make the dynamic characteristics of the rod-fastening rotor bearing system closer to that of the complete rotor bearing system. The increase in the diameters of rods significantly delay the partial separation of the contact surfaces. The smooth contact surface provides higher contact stiffness, but it is not conducive to maintaining the full contact state of the contact surfaces. The stiffness coefficients fluctuate with the deformation of the rotor, and the process is significantly affected by uneven pre-tightening load. Moreover, a self-excited vibration frequency $$f_{l}$$ accompanied by a combination frequency $$f_{b} = 3f_{l}$$ appears when the uneven pre-tightening load is caused by individual faulty rod. The number of rods, rod diameter, and contact surface roughness have similar effects on the dynamic characteristics of rod-fastening rotor bearing systems, which lead to fluent whirl and fluent whip appear in advance, reducing the stability of the system.

Numerous experiments reveal that the dynamics of glass-forming polymer melts are profoundly influenced by the application of pressure, but a fundamental microscopic understanding of these observations remains incomplete. We explore the structural relaxation of a model glass-forming polymer melt over a wide range of pressures (P) by molecular dynamics simulation. In accord with experiments for nonassociating polymer melts and the generalized entropy theory, we find that the P dependence of the structural relaxation time (τα) can be described by a pressure analog of the Vogel–Fulcher–Tammann equation and that the characteristic temperatures of glass formation increase with P, while the fragility decreases with P. Further, we demonstrate that τα for various P can quantitatively be described by the string model of glass formation, where the enthalpy and entropy of activation are found to be proportional, an effect that is expected to apply to polymeric materials under various applied fields.

Li-CO2 batteries have recently attracted attention as promising candidates for next-generation energy storage devices due to their extremely high theoretical energy density. The real application of Li-CO2 cells involves addressing several drawbacks, including high charging potential, poor coulombic efficiency, and low rechargeability. Molybdenum disulfide supported on carbon nanotubes (MoS2/CNT) with various ratios functioned as a cathode catalyst for Li-CO2 batteries. The optimal MoS2/CNT composite achieved a maximum discharge capacity of 8551 mAh g-1 with a coulombic efficiency of 96.7%. This hybrid also obtained an initial charging plateau of 3.87 V at a current density of 100 mA g-1 with a cutoff capacity of 500 mAh g-1. It provided ideal electrochemical stability of 142 cycles at the current densities of 100 mA g-1, which was comparable with that of some precious metal catalysts. This optimized MoS2/CNT was also cycled at 200 and 400 mA g-1 for 112 and 55 times, respectively. Density functional theory calculations demonstrated that the sulfided Mo-edge (s-Mo-edge) on MoS2 materials showed appropriate adsorption strengths of Li, CO2, and Li2CO3. Moreover, joint results of Raman profiles and extended X-ray absorption fine structure spectra elucidated that the catalytic efficiencies of MoS2/CNT hybrids were proportional to the quantities of exposed s-Mo-edge active sites.

The hot deformation behavior of as-cast 9Cr3W3Co oxide dispersion-strengthened (ODS) steel was investigated by Gleeble 3500 facility in the temperature range of 900–1,150℃ and at strain rates range of 0.01–10 s−1. The constitutive equation and processing maps were established to describe this complex hot deformation process. The true stress–strain curves showed that the softening effects of dynamic recovery and dynamic recrystallization are stronger than the effect of work hardening with further increasing the temperature and strain. The optimal hot working parameters of 9Cr3W3Co-ODS steel are suggested to be T = 1,050–1,100°C and ε ̇ \dot{\varepsilon } = 0.03–0.3 s−1.

Aggregation-induced emission (AIE)-active switchable [2]rotaxane TR2 with two different molecular stations and arm-terminated TPE units at both ends, and their derivatives were synthesized by means of threading, followed by the stoppering tactic via click chemistry. The AIE behavior of thread A1 and [2]rotaxanes (TR1, TR2, and TR3) in CH3CN were activated by tuning water fractions (fw), which induced the development of various well-defined nanostructures including spheres, nanorods, truncated cubes, and nanocubes via the self-assembly of scaffolds. These AIE changes and distinct nanostructures formation verify that the reported analogous rotaxanes were controlled by the shuttling movements of the macrocycle along with wide ranges of multi-non-covalent interactions. The anion-templated construction of [2]rotaxane TR2 with a high level of structurally complex design always encounters more challenging tasks. Evidently, the key to the design involved encoding flexible arms on both triazolium motifs, and exhibited an impressive selectivity and sensitivity (with a detection limit of 0.20 μM) towards the complementary H2PO4− ion species. The specific mechanical molecular motion and host–guest interactions of mechanically interlocked molecules (MIMs) were also further explored by quantum mechanical calculations. Importantly, the AIE changes of [2]rotaxanes TR1, TR2, and TR3 were further supported by their bioimaging applications and specifically, [2]rotaxane TR2 could be applied to in vitro imaging with H2PO4− at subcellular levels. This flexible multi-component synthetic strategy affords access to the systematic tuning of molecular structures and self-assembled architectures, and it will inspire further studies on the self-assembly of TPE-containing MIMs for materials science and biological applications.

Graphite has been widely used as the anode material in lithium-ion batteries (LIBs) due to its good conductivity, layered crystal structure, high charging–discharge potential, and other characteristics. With the rapid development of the LIB industry, the graphite industry has also developed into a mode of high production capacity. The anode graphite of spent LIBs has the characteristics of large layer spacing and ease of being intercalated and peeled due to the reduction of the interlamination force after repeated charge and discharge cycles. In this study, we present a facile freeze–thaw ultrasonic assisted circulation method to prepare two-dimensional low-layer graphite flakes (GFs) using anode graphite from spent LIBs. Characterizations of GFs were carried out by SEM, TEM, XRD and Raman spectroscopy. The results indicate that GFs prepared by graphite of spent LIBs have a better morphology than that prepared by purchased graphite. Furthermore, the GF-filled ethylene glycol (EG) nanofluids exhibit higher thermal conductivity and conductive heat transfer coefficient than base fluids, of which the maximum enhancements are 10.5% and 30%, respectively. The freeze–thaw ultrasonic assisted circulation method is not only an effective method for the reuse of anode graphite from spent LIBs, but also a reference for the synthesis of two-dimensional materials. Furthermore, GF-filled nanofluids could be a potential heat transfer working medium.

This study investigates the possibility of the carbon nanotube (CNT)‐based through‐silicon vias (TSVs) for improving power integrity of 3‐D integrated circuits (3‐D ICs). The circuit model is developed for 2‐bit CNT TSV and validated through the full‐wave electromagnetic simulator HFSS simulations. The 2‐bit CNT TSV is applied to power distribution networks (PDNs) by combining the validated equivalent‐circuit model and that TSV‐based PDN impedance is compared with the traditional one. By virtue of the large capacitance and low inductance of the 2‐bit CNT TSV, the PDN impedance of the 3‐D IC can be suppressed significantly and the anti‐resonant frequency can be increased.

This work shows an ultrahigh sensitivity microwave sensor for microfluidic applications. The proposed sensor is made of a microstrip line loaded with a complementary split-ring resonator (CSRR). The meander slot is adopted in the CSRR to achieve high field confinement and is therefore covered with a polydimethylsiloxane (PDMS) microfluidic channel to enable strong interaction between the field and the liquid sample. The complex permittivity of the liquid sample can be retrieved by the variations in the resonant frequency and peak attenuation. The proposed design requires a very small liquid volume of $\sim 0.5~\mu \text{L}$ while offering a high sensitivity. A prototype is fabricated and tested, with a good agreement achieved between the extracted values and the reference data.

The deepwater cable bending restrictor is an important protective device for risers, umbilicals and cables in offshore engineering, protecting cable structure by controlling minimum bending radius. Its mechanical properties are analysed based on the numerical analysis model and finite element analysis (FEM) of ø175. The sensitivity analysis of using quantity of bending restrictors is also performed to show the effect of the quantity on bending stiffness. A testing scheme of bending stiffness of the bending restrictor is then formulated based on its structure. From numerical analysis results through test simulation, the tolerance is less than 3 %, which verifies the reliability of the numerical analysis model. Performance of the bending restrictor and dynamic response are analysed according to environmental parameters that occur once per 100 years from offshore wind power farms and pipein-pipe models, respectively. The results show the bending restrictor can effectively protect cable structure, and the pipein-pipe model is suitable for calculating mechanical properties of interaction between the bending restrictor and cable.

The influence of the monomer chemical structure and architecture on polymer glass formation has been long appreciated to be dominated by two principal molecular factors, namely, cohesive energy and...

Hetero-structure of AlxGa1-xN/GaN exhibits important applications in high frequency and large power devices. In this paper, AlN/GaN is adopted to optimal design the large power impact avalanche transit time (IMPATT) and mixed tunneling avalanche transit time (MITATT) diodes operating at the atmospheric low loss window frequency of 0.85 THz. The static state and large signal characteristics of the devices are numerically simulated. The values of peak electric field strength, break-down voltage, avalanche voltage, the maximum generation rates of avalanche and tunneling, admittance-frequency relation, output power, conversion efficiency, quality factor of the proposed hetero-structural IMPATT and MITATT diodes are calculated, respectively. Via comparing the obtained results of (n)AlN/(p)GaN and (n)GaN/(p)AlN IMPATT diodes to those of the MITATT counterparts, there exists little performance difference between IMPATT and MITATT devices while implies significant difference between the (n)AlN/(p)GaN and (n)GaN/(p)AlN diodes.

Successes of GaN and SiC electronics in high frequency, large power realm indicate that, the GaN/SiC hetero-structures can be used to design the impact avalanche transit time (IMPATT) diodes operating at Terahertz range, of which holds advantages over homo-structural counterparts in lower noise and reduced tunnel current. Here, the (n)GaN/(p)SiC and (p)GaN/(n)SiC double drift region (DDR) IMPATT diodes operating at 0.85 THz are proposed based on the quantum corrected drift-diffusion (QCDD) model, the performance parameters of static state, large signal and noise properties of the studied devices such as peak electric field intensity, breakdown voltage, optimal negative conductance, output power, conversion efficiency, admittance-frequency relation, quality factor, noise electric field, mean-square noise voltage per band-width and noise measure were numerically calculated and analyzed, which can guide to optimize the GaN/SiC IMPATT diodes.

The performance of gas sensors based on micro-heater is highly dependent on the environment temperature, heater temperature, and gas flow rate. The performance fluctuation of gas sensors induced by environment temperature drift can be reduced in different ways. In this article, different sizes and shapes of obstacles are placed around the sensitive component of the thermal conductivity gas sensor to study the effect of gas flow rate on the gas sensor performance. Both the simulation and experiment results indicate that the obstacle design can reduce the interference of gas flow rate on gas sensor performance. As the obstacle size increases, the influence of gas flow rate decreases and the dynamic detection accuracy of the gas sensor increases at the same gas flow rate, and the voltage variation of the sensor with quadrangular prism obstacle shape is minimal, and the gas velocity reduction effect is 1.77% better than cylinder obstacle shape. The effect of gas flow rate on the gas response is also investigated by detecting the voltage response of the MG811 gas sensor with and without thermostatical control. The result shows that the gas flow rate not only reduces the temperature of the sensor (direct influence), but also promotes the chemical reaction of the sensor, which releases a large amount of heat (indirect influence). The corresponding relationship between voltage response and gas flow rate is obtained through controlling the temperature of sensitive components thermostatically. This article provides a new angle for improving the accuracy of the gas sensor in different gas flow rate environments, which can improve the detection rate of the wireless monitoring system.

We adopt Langevin dynamics to explore the stress-structure relationship of telechelic reversible associating polymer gel during startup shear flow, with shear strengths varying from Wi = 12.6 to Wi = 12640. At weak shear flow Wi = 12.6, the shear stress proportionally increases with shear strain at short times, followed by a strain hardening behavior and then passes through a maximum (σmax, γmax) and finally decreases until it reaches the steady state. During the evolution of stress, the gel network is only slightly broken and essentially maintains its framework, and the strain hardening behavior originates from the excessive stretching of chains. On the other hand, the stress-strain curve at intermediate shear flow Wi = 505.6 shows two differences from that at Wi = 12.6, namely, the absence of strain hardening and a dramatic increase of stress at large strains, which is caused by the rupture of gel network at small strains and the network recovery at large strains, respectively. Finally, at very strong shear flow Wi = 6319.7, the gel network is immediately broken by shear flow and the stress-strain curve exhibits similar behaviors to those of classical polymeric liquids.

The directional structure of Ni60/high-aluminum bronze composite coating was formed using induction remelting and forced cooling. The microstructural evolution and the characteristics of interface growth were studied. The results showed that the remelted coating formed metallurgical bonding with the substrate. The microstructures changed from plane crystal to dendrite, cellular dendrite, fine cellular dendrite, and then to dendrite again with the increase in the cooling rate. The crystal grew along the heat flow direction and had (111) and (200) preferred orientations when the cooling rate was 1.886 ml·min−1·mm−2. The plane crystal, dendrite and cellular dendrite were mainly composed of compounds and solid solutions with Ni, Fe and Cu, and they were surrounded by strengthening phases composed of Cr, C and B. The grain boundary of directional structure coatings showed the characteristic of regular eutectic growth, but grain boundary of remelted coating presented characteristic of divorced eutectic growth. The wear resistance of directional structure coatings is better than that of remelted coating.

The generalized entropy theory (GET) of glass formation provides an analytic framework for the structural relaxation time and thermodynamic properties of glass-forming polymers in terms of molecula...

Motivated by empirical observations suggesting that changes in the activation volume ΔV# upon varying temperature (T), determined from the pressure (P) dependence of the segmental structural relaxa...

The hot deformation behavior and microstructure evolution of Al-3.5Cu-1.0Li-0.4Mg- 0.6Zn-0.3Ag aluminum lithium alloy were investigated by hot tensile tests on Gleeble-1500 thermal simulator at 480-510 °C and strain rates 0.0001-0.1 s-1. The results show that obvious flow steady-state phenomena occur during hot stretching and the main mechanism changes from dynamic recovery to dynamic recrystallization with the increase of temperature and decrease of strain rate. The constitutive equation was calculated using the true stress-strain curve obtained by the hyperbolic sinusoidal pair of deformation activation energy Q and temperature T proposed by Sellars and Tegart. The deformation heat activation energy is 226.783 KJ/mol.

The hybridization of 1,4-bis(isoquinoline)butane (BIQBT2+) cation with iodobismuthate under different solvents produce two isomers α-[(BIQBT)(BiI4)2]n (α-1, in CH3OH/H2O mixed solvent, Triclinic system with P-1 space group) and β-[(BIQBT)(BiI4)2]n (β-1, in CH3OH, Monoclinic system with P21/c space group). The 1-D (BiI4) n n− chains are constructed from the opposite edge-sharing BiI6 octahedra. The (BIQBT)2+ in α-isomer adopts the planar configuration, and that in β-isomer presents the chair-like configuration, as a result, different packing modes (intercalating quasi-3-D mode for α-1 and interlocking 2-D mode for β-1) are observed. Interestingly, from α-1 to β-1, distortion degree of BiI6 octahedron and π–π stacking interaction decrease, but hydrogen bonds number increase. Consequently, due to different packing mode, photoluminescence/thermochromisms can be found in α-1, but those of β-1 are vanished, Theoretical calculation was conducted to disclose the structure/thermochromism correlation.

The key role of chain flexibility in polymer glass formation has long been appreciated, but a fundamental understanding of how chain stiffness influences polymer glass formation remains elusive. In...

This paper presents a differential microwave microfluidic sensor based on the microstrip complementary split-ring resonator (MCSRR) structure for liquid characterization. At the resonance, the electric field concentrates along the slot, where the microfluidic channel is located. As the liquid sample is injected, the corresponding reflection coefficient is changed, while the reference response is unaffected. The relative permittivity and loss tangent of the liquid can be extracted from the variations in the resonant frequency and quality factor. A prototype of the proposed sensor is fabricated and measured for functionality validation. The proposed sensor exhibits a high sensitivity of 0.626% on average and is capable of suppressing unwanted environmental influences.

Exploring active Pt catalysts is essential both in academic and economic for glycerol oxidation. In this paper, a method for the synthesis of highly efficient Pt@Co-NC catalyst for glycerol oxidation was studied. Pt@Co-NC was synthesized by pyrolyzing the composite of Pt nanoparticles (NPs) encapsulated in ZIF-67 (Pt@ZIF-67). Transmission electron microscopy analysis showed that Pt existed in the form of PtCo NPs and PtCo alloys, and X-ray photoelectron spectra analysis demonstrated the interaction of Pt and Co-NC. These results indicated that the activity of Pt@Co-NC by this work was superior to that of Pt/Co-NC by conventional methods, including the polyol reduction method, galvanic replacement method, and sol-gel method. Pt@Co-NC was used five times without deactivation, suggesting its high reusability. The high reusability and activity of Pt@Co-NC were attributed to its structure caused by the synthetic methods. The pore confinement and the interaction of Pt and Co-NC played a key role in the high reusability and activity of Pt@Co-NC.

A nickel alloy matrix high-temperature self-lubricating coating (77.5 wt% (Ni–Cr–Mo–Al)–12.5 wt% Ag–10 wt% BaF2/CaF2) was prepared by plasma spraying technique. Results show that the Vickers microhardness of coating is (2.9 ± 0.5) GPa, and the average bonding strength is about (35.6 ± 0.5) MPa. The coating rubbing against Inconel 718 superalloy pin exhibits superior tribological performance with coefficient of friction (COF) of below 0.25 and wear rate of 8.2 × 10–5–15.2 × 10–5 mm3·N−1·m−1 at a wide temperature range from 25 to 800 °C, and the COF and the wear rate are slightly reduced with temperature increasing. The low COF and wear rate were attributed to the synergistic effects of Ag, BaF2/CaF2, Ag2MoO4 and BaMoO4.

A series of aggregation-induced emission (AIE) active polysiloxanes (P7-1~P7-2, P29-1~P29-6) were prepared through hydrosilylation between polymethylhydrosiloxane (PMHS, DP=7 or 29) and AIE-active vinyl monomer 1-(4'-allyloxy-biphenyl)-2,5-diphenyl pyrrole (M-TPP), or with optical active monomer cholesteryl allyloxy ether (M-Chol*). Monomer M-TPP and all of the polymers exhibits aggeragation-induced emission enhancement properties. The fluorescence intensity of M-TPP in THF/H2O mixtures increases when the water fraction is higher than 60%, while is over 20% for polysiloxanes, which mainly because the entanglement of the flexible polysiloxane main-chain can restrict the molecular motion of triphenylpyrrole (TPP) derivates and induce the increasing of the fluorescence intensity. Moreover, the maximum relative fluorescence intensity (I/I0) is equal to 4 for M-TPP and 1.4~4.9 for polysiloxanes, and the grafted degree of the TPP derivative has effect on the AIE properties of polymers. The specific optical rotations of the chiral polymers increase with increasing the content of chiral cholesteryl ether moieties. All the target polymers possess good thermal stabilities and their decomposition points (Td) are greater than 320°C.

Numerical simulation was carried out to investigate the gas-liquid two-phase flow-induced corrosion in high productivity gas wells containing carbon dioxide. The Eulerian-Eulerian multiphase model combined with the electrochemical corrosion model was applied to simulate the corrosion rate at the tubing thread connection induced by corrosive medium containing carbon dioxide. The predicted corrosion rate was compared with the field data in the literature. It is shown that the predicted results were conservative when merely considering the phase distribution. Qualitative analysis between the predicted phase distribution, flow characteristics, erosion-corrosion position and the field data was made.

The optimal design of repeaters for current-mode (CM) nano-interconnects is conducted and compared with that for voltage-mode (VM) ones. Both Cu and carbon nanotube (CNT) nano-interconnects are considered and studied, with the contact resistance treated appropriately. In comparison with the VM ones, the CM nano-interconnects can not only demonstrate better electrical performance, but also require fewer repeaters, thereby saving more valuable chip area. In the delay-optimal repeater design of multi-walled CNT interconnects, for instance, the optimal number of repeaters can be reduced by 120% with the implementation of CM signalling scheme.

By the virtue of multibit through-silicon via (TSV), which consists of carbon-nanotube (CNT)-filled TSV with separate metal pads, design of compact differential multibit CNT TSVs (DMC-TSVs) is proposed and studied. For modeling such DMC-TSVs, an equivalent circuit model is introduced, in which the partial-element equivalent circuit (PEEC) method is adopted to extract the impedance. Moreover, the circuit model is simplified as an odd-mode half-circuit and is used to design passive resistor–inductor ( RL ) equalizer.

For a closed working environment, the CO2 content in the air in a closed space will rise continuously due to personnel breathing and some equipment or electronic devices, and even exceed the allowable content in the normal working environment. In order to prevent the CO2 content from exceeding the standard in the closed working environment, the method of low temperature liquefaction is used to separate the CO2 in the air. Through simulation calculation and comparison of key parameters of the process of using cascade liquefaction and nitrogen expansion liquefaction to reduce CO2 concentration in air, it is concluded that it is feasible to use cryogenic liquefaction method to separate carbon dioxide from air to purify air and improve air quality in confined space.

This paper presents two complementary split-ring resonator (CSRR)-based sensors for full characterization of magneto-dielectric materials. The first proposed sensor is designed by loading the microstrip line with a CSRR, while the second one is by loading the microstrip line with two CSRRs. To distinguish the effects of permittivity and permeability on the shift of resonant frequency, the electric and magnetic fields are designed to be located at two separate zones in the CSRR. Two 50Ω resistors are mounted at the ends of the microstrip line to increase the quality factor. In addition, the second sensor can perform measurements of complex permittivity and complex permeability of the magneto-dielectric materials in a single run, thereby making the measurement faster, easier, and in a more cost-effective way. The prototypes of two proposed sensors are fabricated and tested for validation of their functionality. A good agreement can be achieved between the measured data and the reference values from the manufacturers' datasheet, thereby demonstrating the applicability of the proposed sensors for full characterization of the magneto-dielectric materials.

We present an analytical protocol for in situ U–Pb isotope dating of wolframite series minerals [(Fe,Mn)WO4], the main ore mineral for tungsten, by LA-SF-ICP-MS. Precision and accuracy of the protocol was intensively assessed using our newly developed well-characterized U–Pb wolframite reference material. The tungsten oxide interference on Hg and Pb was investigated in detail. The matrix effect between ferberite and hübnerite during laser ablation was thoroughly examined for wolframite series minerals with a different Mn/(Mn + Fe) ratio. The closure temperature of wolframite, with respect to the U–Pb system, was evaluated. The application of eleven wolframite samples, with ages from ∼1780 Ma to ∼26 Ma, robustly demonstrated the feasibility of our approach. Most studied wolframite series minerals yielded U–Pb concordant or subconcordant ages. Samples with a relatively high U content and negligible common Pb content typically had a 206Pb/238U age precision of ca. 1%. The new in situ data agree well with published cassiterite or wolframite ages from the same locations. LA-SF-ICP-MS, with the advantages of high sensitivity, rapidity, and relatively low cost, as well as moderate spatial resolution (i.e., 32 or 44 μm) that is sufficiently high to avoid sulfide inclusions, is the method of choice for in situ wolframite U–Pb microanalysis.

This article proposes a novel differential through-silicon via (D-TSV) structure, which is filled with vertically aligned carbon nanotube (VACNT) array. Two metal pads are deposited on the sides of the surface of the proposed D-TSV to form differential signal transmission paths. The equivalent circuit model is established for the proposed D-TSV, with the frequency-dependent impedance extracted using partial-element equivalent-circuit (PEEC) method. By virtue of the equivalent circuit model, the electrical performance of the proposed D-TSV is investigated, with some design guidance presented.

Rechargeable Na–CO2 batteries are promising energy storage devices as they not only provide high energy density but also utilize earth-abundant Na and the greenhouse gas CO2. However, Na–CO2 battery development is deterred due to the sluggish electrochemical reactions at the cathode. The cathode catalyst is unable to decompose the insulating discharge product Na2CO3, thereby leading to increasing charge overpotential and poor cycle performance of the Na–CO2 battery. Herein, we report spinel ZnCo2O4 porous nanorods with multiwall carbon nanotubes (ZnCo2O4@CNT) as a cathode composite in the Na–CO2 batteries to effectively decompose Na2CO3 and improve the cycle performance. The battery shows stable discharge–charge for at least 150 cycles with a limited capacity of 500 mA h g−1 at 100 mA g−1. Moreover, the battery with the ZnCo2O4@CNT cathode catalyst exhibits a reversible discharge–charge capacity of 12 475 mA h g−1. Theoretical simulations suggest that the adsorption energies of CO2, Na, and Na2CO3 on the three surfaces of ZnCo2O4 are favorable for the CO2RR and CO2ER during the charge–discharge of the Na–CO2 battery. The surfaces of ZnCo2O4 investigated for catalytic activity include the [001] surface, the [111] surface with only exposed Co atoms, and the [111] surface with exposed Co and Zn atoms. The density of states calculation results further reveal that Co atoms on these three surfaces are possibly the catalytic active sites for the CO2RR and CO2ER during the charge–discharge of the Na–CO2 battery.

Numerical simulation of fully coupled electrothermal processes in phase-change memory (PCM) arrays is performed in this article. For realizing the ability in simulating the electrothermal responses of large-scale PCM arrays, an in-house parallel simulator based on domain decomposition method (DDM) and time-domain finite element method (FETD) is developed, with its performance evaluated in terms of accuracy and scalability. Then, thermal crosstalk in the PCM array is investigated using the developed simulator, and a diamond layer is introduced to suppress thermal crosstalk. Furthermore, the scaling effects of PCM arrays on their electrothermal performance are examined. A scheme for multibit PCM design is proposed, and the electrothermal characteristics of proposed 2-bit PCM cells and arrays are studied numerically.

Effects of slag composition and alloy content as well as temperature on the deoxidation and desulfurization of Inconel 718 superalloy by CaF2-CaO-Al2O3-MgO-TiO2 ESR-type slag without the addition of a deoxidizer were systematically investigated by laboratory-scale experiments and the developed mass transfer model. The model predictions were verified through comparison with experimental results in a double-layer crucible. The results showed that the oxygen content decreased with an increase of CaO, MgO and CaF2 content in the slag at 1773 K, and CaO has a great influence on the deoxidation of Inconel 718 alloy compared with MgO and CaF2 in slag, which was responsible for the decrease in equilibrium content of sulfur in the Inconel 718 alloy. The total oxygen and sulfur content decreased from 33.2 and 20 ppm in master alloys to about 10 and 6 ppm in alloy ingots at 1773 K, respectively. Properly increasing the Al and Ti content only lowered the oxygen and sulfur content in the nickel-based alloy to a limited extent when satisfying the mechanical properties of the Inconel 718 alloy. The interfacial oxygen content increased with increasing temperature, giving rise to a decrease in the desulfurization ratio $$ \left( {{{[{\text{pct S}}]_{t = t} } \mathord{\left/ {\vphantom {{[{\text{pct S}}]_{t = t} } {[{\text{pct S}}]_{t = 0} }}} \right. \kern-0pt} {[{\text{pct S}}]_{t = 0} }}} \right) $$. These results show that the lower temperature favored desulfurization of the nickel-based alloy.

The mechanical performance of cemented paste backfill (CPB) placed in deep stopes often differs from laboratory-predicted performance, and the strength of CPB is generally determined to the uniaxial compressive strength (UCS) after the predetermined curing ages in laboratory. However, in situ backfilled stopes, the CPB is enclosed by the orebody and surrounding rocks usually, and the mechanical performance of CPB should not only be determined by the UCS. To investigate the mechanical performance of CPB in deep stopes during long-term service, the physical and mechanical conditions of CPB in situ backfilled stopes were simulated by the confined high-stress consolidation (CHSC), and the microstructure of CPB made by scanning electron microscopy was analyzed, and the strength regeneration mechanism of CPB was investigated from the microscopic point of view. The results showed that the strength of CPB in deep stopes could be excited to various degrees during long-term service, and the degree of excitation was closely related to the curing ages of CPB. The degree of excitation of the CPB strength was determined by the maximum confined consolidation stress, and the consolidated CPB was more beneficial to its supporting role in engineering. The macroscopic strength of CPB after CHSC can be increased by the increase of bond strength at the interfacial transition zone and the improvement of overall compactness of CPB. The re-filling and re-cementation of micro-cracks result in the strengthening of CPB during the re-curing ages. Compression consolidation (primary consolidation) and chemical consolidation (sub-consolidation) of CPB in the backfilled stopes occur simultaneously, and this is obviously different from the process of the compression consolidation of soil.

Hydrogels are cross-linked polymers suitable for various applications, but the thermal conductivities of hydrogel-based composites have not been thoroughly investigated. In this study, agarose hydrogel-based composites with various boron nitride (BN) fillers were synthesized and their thermal conductivities were systematically investigated. With the increase in the agarose content from 1.5 wt% to 3.0 wt%, the thermal conductivity of the composite decreased. The composites with BN micropowder had larger thermal conductivities than those of the composites with BN nanopowder at the same filler loading, as the BN micropowder provided better thermal conduction pathways in the hydrogel matrix than those provided by the nanopowder. The maximum thermal conductivity of 2.69 W·m−1·K−1 was achieved when 15 wt% microscale BN fillers were added into 1.5 wt% agarose hydrogel, which was 3.5 times larger than that of the pure agarose hydrogel. Additionally, a theoretical model was used to calculate the thermal conductivities of the BN/agarose hydrogel composites; a good agreement was achieved between the experimental and fitting ones. This study demonstrated that the thermal conductivities of hydrogel-based materials can be efficiently and significantly enhanced using BN fillers.

The macro- and microstructures, chemical compositions, microsegregations, and nonmetallic inclusion characteristics at different positions of the as-cast IN718 ingots produced by a laboratory-scale electroslag remelting (ESR) furnace under four remelting currents (150, 200, 250, and 300 A) were compared and investigated comprehensively. The results indicate that the average melting rate increases with the increasing remelting current, and the molten pool tends to be deeper. Thus, at the same position of the ESR ingots, the volume fraction of the segregated phase, the degree of elemental segregation, and the secondary dendrite arm spacing have the same tendency to increase with the increasing remelting current and show an increasing trend from the bottom to the top along the height of each ingot. If the current is set relatively low, the oxygen and nitrogen levels in the ingots increase, the conditions that make the contents and distributions of Al and Ti become unstable. In addition, the major nonmetallic inclusions in the IN718 ESR ingots are MgO·Al2O3 complex oxide inclusions with a three-layer structure and (Nb,Ti)N nitrides. The volume fractions and mean equivalent diameters display a downward trend with the increasing remelting current. The size and quantity of these inclusions are always larger in the upper portions of the ingots than those in the lower portions.

Single-layered FePt films of 30 nm thickness with random orientation are produced by direct current magnetron sputtering (DCMS) deposited directly onto Corning 1737 glass substrates and then post-annealed at 700 °C for 30 min. In films produced by high power impulse magnetron sputtering (HiPIMS) however, a strong (001) texture of L10 FePt film with isolated island structure is achieved and presents high perpendicular magnetic anisotropy after post-annealing under the same conditions. This is due to the compressive stress in as-deposited FePt films being enhanced greatly by HiPIMS. The films achieved by HiPIMS possess perpendicular coercivity, saturation magnetization and perpendicular squareness of 14.2 kOe, 620 emu/cm3 and 0.98, respectively, which reveal HiPIMS as a good technique to produce single-layered FePt films with high perpendicular magnetic properties.