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This article presents an accurate analytical model to compute the magnetic field in a short moving-magnet linear motor with any pole and slot combinations. Two kinds of end effects caused by the finite length of the stator and mover are considered. The stator end effect is addressed by an equivalent slotting subdomain based on the subdomain analytical method. The mover end effect is analyzed with a virtual mover consisting of the mover and two additional virtual units. The length of virtual unit is given according to the effective motion stroke and magnetic circuit, and the remanence of permanent magnets in virtual units is specified as zero. A linear motor with 8 poles/6 slots and a Halbach array is used to verify the correctness of the proposed analytical model. Compared with the results from the finite-element analysis and previous subdomain analytical model, the proposed analytical model shows high accuracy on the calculations of the magnetic flux density, cogging force, and normal magnetic force.

By direct calcination of Cu2+-doped ZIF-8 in oxygen atmosphere, a new photoelectric material, CuO–ZnO heterojunction, was prepared. The morphology and structure were investigated in detail by several methods, such as scanning electron microscopy, transmission electron microscopy, nitrogen adsorption-desorption method and X-ray diffraction. Under visible light irradiation, CuO–ZnO heterojunction exhibits excellent PEC behavior in aqueous media with the presence of ascorbic acid (AA) and dissolved oxygen at −0.3 V. Taking the CA125-antibody functionalized CuO–ZnO heterojunction (CuO–ZnO-Ab2) as a signal source, a novel photoelectrochemical (PEC) immunosensing platform was developed for ultrasensitive assay of CA125. Because of the target-induced introduction of photoelectric material to the sensing platform, the proposed PEC immunosensor has excellent performance for CA125 assay: near-zero background noise, wide linear response range (1 × 10−5 U/mL to 100 U/mL) and low detection limit (3.16 × 10−6 U/mL). The developed CuO–ZnO heterojunction and the related PEC sensing platform may have promising applications in ultrasensitive and highly accurate monitoring of various proteins in bioanalysis and disease diagnosis.

NiFe LDH (layered double hydroxide) is currently attracting increasing attention as a type of promising electrocatalyst for oxygen evolution reaction (OERs); however, the biggest obstacle to its large-scale practical application is its poor conductivity and limited active sites. Herein, we report a three-dimensional NiFe LDH with high conductivity and dense active sites, where amorphous NiFe LDH nanosheets are directly electrodeposited on the surface of a hierarchical porous NiCoP@NC derived from the calcination and phosphorization of metal-organic frameworks (ZIF-67) in situ grown on nickel foam. Based on the 3D porous structure, abundant exposed active sites, fast electron and mass transfer rates and strong synergetic effects between NiCoP@NC and NiFe LDH, the resultant NiFe LDH/NiCoP@NC/NF catalysts exhibited significantly enhanced OER catalytic performances compared with NiFe LDH on nickel foam and most of the reported NiFe LDH-based catalysts: a low overpotential of 210 mV for yielding a current density of 10 mA cm-2, an extremely small Tafel slope (35 mV dec-1) and excellent durability. For overall water splitting, with NiFe LDH/NiCoP@NC/NF as the anode and NiCoP@NC/NF as the cathode, the assembled two-electrode system only required 1.54 V to obtain a stable current density of 10 mA cm-2 in 1 M KOH for at least 40 h. This research provided a simple and facile way to develop non-noble-metal oxygen evolution catalysts for replacing high-cost noble metal catalysts.

Jianmiao Wang,1 Yuping Zhang,1 Yuanyuan Chen,2 Mei Li,1 Hongyan Yang,2 Jinhua Chen,2 Qiaomin Tang,2 Jingfen Jin1,3 1Nursing Department, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, People’s Republic of China; 2Neurology Department, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, People’s Republic of China; 3Changxing Branch Hospital, The Second Affiliated Hospital of Zhejiang University School of Medicine, Huzhou, Zhejiang Province, People’s Republic of ChinaCorrespondence: Jingfen JinThe Second Affiliated Hospital of Zhejiang University School of Medicine, No. 88 Jiefang Road, Shangcheng District, Hangzhou, Zhejiang Province, 310009, People’s Republic of ChinaFax +86-0571-87783778Email zrjzkhl@zju.edu.cnPurpose: To determine the effectiveness of rehabilitation nursing program interventions in patients with acute ischemic stroke.Patients and Methods: An assessment-blinded randomized controlled trial was conducted at a tertiary referral hospital in China. Eligible patients were stratified according to their weighted corticospinal tract lesion load and then randomly assigned to an experimental group (n = 121) or a control group (n = 103). The experimental group received rehabilitation nursing from well-trained, qualified nurses (30 minutes per session, two sessions per day for seven consecutive days). The control group received therapist-led rehabilitation with the same timing and frequency. Comparative analysis of the primary outcomes was performed to determine non-inferiority with a predetermined non-inferiority margin. The primary outcomes were the Motor Assessment Scale, Fugl-Meyer Assessment, and the Action Research Arm Test assessed at baseline and after seven days of treatment. The secondary outcomes were the modified Barthel Index, the National Institutes of Health Stroke Scale, and the modified Rankin Scale, evaluated before and after the intervention and at 4 and 12 weeks of follow-up.Results: Two hundred participants completed the trial. In both groups, all outcomes improved significantly after seven days and at follow-ups. The rehabilitation nursing program was non-inferior to therapist-led treatment with lower 95% confidence limits beyond the margins for primary outcomes (P < 0.001).Conclusion: Both treatments had comparable effects; however, no definite conclusion could be drawn. Adequately powered studies are required.Keywords: rehabilitation, nursing, acute ischemic stroke, motor function

In this paper, the transmission performances are studied in cognitive radio networks with primary user emulator and relay existence. In the proposed network, the users include primary users, secondary users and primary user emulators. The decreasing access priority of the users are primary users, primary user emulators and secondary users. Different user access to the network results in different transmission effects. We impose interference power constraints on the secondary users to protect the primary users from being interfered. We also adopt the transmission mechanism that transits among more than one secondary transmitters, secondary receivers and relays. The transition models of the transmission states are proposed to describe the transmission mechanism. To investigate the transmission performances, the theory of effective capacity is adopted. The transmission performances in terms of effective capacity are expressed and demonstrated under different transmission policies. The overall effective capacity, as the overall data traffic in the cognitive radio network, is calculated. Besides, the overall effective capacity is demonstrated under different transmission strategies. The results show the greedy transmission strategy outperforms the rest of the transmission policies in the overall effective capacity. For a larger number of the users, the effective capacity converges to a certain value.

This paper presents the magnetic field analysis for the double layer Halbach array voice coil actuator (VCA). This VCA is composed of a stator and a mover supported by the flexure-based bearings. The mover gets three coils winded on the skeleton. The stator comprises the closed yoke and the double layer Halbach array permanent magnets (PMs). The boundary condition of the quadrangularly surrounded yoke and the aperiodic distribution of the Halbach array PMs complicate the magnetic analysis process. An equivalent VCA structure that has almost identical air-gap flux distribution to the original one is, therefore, proposed. For the equivalent structure, the boundary condition is simple and the Halbach array PMs is periodically distributed, thus the analysis process of air-gap flux density distribution via Fourier analysis is simplified. The equivalence between these two structures is validated by finite-element analysis (FEA). The analytical model is built by adopting Fourier analysis. The results of the FEA and experiments confirm the correctness of the developed model and prove the feasibility of the analytic method with the equivalent structure.

To investigate an air distribution system with the potential to provide a comfortable thermal environment and efficient ventilation performance in heating mode, this study compared the numerical results of the RNG k-[Formula: see text] model, realizable k-[Formula: see text] model and SST k-ω model with experimental data obtained from a typical office with wall confluent jets ventilation (WCJV) for heating. The SST k-ω model was chosen for numerical study of WCJV. The findings showed that the WCJV performed better than mixing ventilation (MV) in the heating mode because WCJV could entrain less ambient air and maintain the jets’ momentum and energy to reach the occupied zone. The effects of supply air temperature difference (in the range of 2.00°C to 7.79°C) and supply air velocity (in the range of 2.20 m/s to 8.50 m/s) on the jet velocity profiles and ventilation performance of WCJV were also quantified. The results showed that the jet velocity profile was more sensitive to the supply air velocity than to the supply air temperature difference. Accordingly, reducing the supply air velocity might result in poorer thermal environment and air quality in the occupied zone because the warm air jets cannot spread out over the floor area. The results can be helpful in understanding WCJV used for ventilation under heating mode.

The development of non-platinum catalysts for the oxygen reduction reaction (ORR) to substitute state-of-the-art but expensive Pt catalysts is essential for the development and practical application of fuel cells. Here, combining the self-assembly and coordination interaction between graphene oxide (GO) with g-C3N4 and iron phthalocyanine (FePc), FeNx atom clusters supported on three-dimensional porous nitrogen-enriched graphene carbon aerogels were successfully prepared by one facile solution method. The obtained FeNx atom cluster catalyst (FeNx-CN/g-GEL) exhibited superb catalytic performance (E1/2 = 0.90 V) toward the ORR, which is superior to that of commercial Pt/C (E1/2 = 0.835 V) and the currently reported non-noble nanocatalysts. Additionally, the catalyst displayed a high metal utilization rate with a mass specific activity of 840 mA mgFe−1 at 0.80 V, excellent long-term stability with only a little decline after the 28 000 s test and remarkable tolerance to methanol and SCN−.

A modified Gilbert down-conversion mixer for 77-GHz automotive radar application is presented in this paper. By replacing the resistive loads with active loads composed of resistors and PMOSs, the output DC voltage becomes stabler, and the suppression of even-order components is improved. Fabricated in 40-nm CMOS technology, the proposed mixer occupies a core chip area of $0.25 \times 0.26$ mm2. The DC power consumption is only 1.5 mW with a 1-V supply. The measured maximum voltage conversion gain is 4.8 dB at LO frequency of 78.5 GHz and IF frequency of 20 MHz. The input 1-dB compression point is 0.8 dBm. Measured results also show that the reflection coefficient of the RF port is less than -11 dB from 74 to 83 GHz.

In this paper, Hilbert-Huang transform(HHT) is used to study the HHT method of feature extraction from rotor vibration signals. Firstly, HHT signal analysis program is established by Matlab. Secondly, rotor unbalanced vibration experiment is carried out on the DH Rotor Experiment Platform. Besides, the collected rotor vibration signal is processed by HHT and the processing results are analyzed. Experimental results show that the HHT method can distinguish the unbalanced default characteristic spectrum in the rotor vibration signal effectively

Nitrogen doped porous carbon nanopolyhedra (N-PCNPs) were prepared from direct carbonization of ZIF-8 nanopolyhedra. The N-PCNPs showed uniform morphology, narrow pore-size distribution centered at 3.7 nm, high surface area (2221 m2 g−1) and good electrochemical properties and were used to modify a glassy carbon electrode to electrochemically detect ascorbic acid (AA), dopamine (DA) and uric acid (UA). Compared with the bare GC electrode and reduced graphene oxide modified glassy carbon (rGO/GC) electrode, the N-PCNPs modified GC electrode (N-PCNPs/GC) was found to perform better toward electrocatalytic oxidation of AA, DA and UA. For simultaneous sensing of three analytes, three well-separated voltammetry peaks were obtained using the N-PCNPs/GC electrode in differential pulse voltammetry measurements, and the corresponding peak separations between AA and DA, DA and UA were 228 mV, 124 mV respectively. The linear response ranges for the determination of AA, DA and UA were 80–2000 μM, 0.5–30 μM and 4–50 μM, respectively, and the detection limits (S/N = 3) were 740 nM, 11 nM and 21 nM, respectively. Furthermore, the N-PCNPs/GC electrode showed good reproducibility and stability. The attractive features of N-PCNPs provided potential applications in the simultaneous determination of UA, AA and DA.

Chinese and Indian medical tradition, each had its own merits and their exchange dated back to ancient times and lasted over centuries. And their encounters often produced unexpected fruitful outco...

In this work, high-performance non-enzymatic catalysts based on 3D hierarchical hollow porous Co3O4 nanododecahedras in situ decorated on carbon nanotubes (3D Co3O4-HPND/CNTs) were successfully prepared via direct carbonizing metal-organic framework-67 in situ grown on carbon nanotubes. The morphology, microstructure, and composite of 3D Co3O4-HPND/CNTs were characterized by scanning electron microscopy, transmission electron microscopy, micropore and chemisorption analyzer, and X-ray diffraction. The electrochemical characterizations indicated that 3D Co3O4-HPND/CNTs present considerably catalytic activity toward glucose oxidation and could be promising for constructing high-performance electrochemical non-enzymatic glucose sensors and glucose/O2 biofuel cell. When used for non-enzymatic glucose detection, the 3D Co3O4-HPND/CNTs modified glassy carbon electrode (3D Co3O4-HPND/CNTs/GCE) exhibited excellent analytical performance with high sensitivity (22.21 mA mM−1 cm−2), low detection limit of 0.35 μM (S/N = 3), fast response (less than 5 s) and good stability. On the other hand, when the 3D Co3O4-HPND/CNTs/GCE worked as an anode of a biofuel cell, a maximum power density of 210 μW cm−2 at 0.15 V could be obtained, and the open circuit potential was 0.68 V. The attractive 3D hierarchical porous structural features, the large surface area, and the excellent conductivity based on the continuous and effective electron transport network in 3D Co3O4-HPND/CNTs endow 3D Co3O4-HPND/CNTs with the enhanced electrochemical performance and promising applications in electrochemical sensing, biofuel cell, and other energy storage and conversion devices such as supercapacitor.

The recently emerging renewable energy industry has boosted a research hot in searching for bifunctional electrocatalysts for water splitting. CoSe2, as one of transition-metal chalcogenides, has attracted particular attention because of its abundant resource, low cost, high efficiency and stability. However, further enhancing catalytic activity of CoSe2 to meet the large-scale application requirements of hydrogen energy remains an important challenge. Herein, three-dimension (3D) Mo-doped porous CoSe2 nanosheet array was directly formed on commercial Ni foam (Mo-CoSe2 NS@NF) electrode through a three-step process including electrodeposition, hydrothermal and subsequent selenylation. Systematically experimental research and density functional theory calculations confirmed that, based on active site and intermediate modulation effect of Mo doping, the obtained 3D Mo-CoSe2 NS@NF electrodes were provided with enlarged electrochemical active surface area, improved charge transport capability and significantly optimized binding energy for active intermediates of the potential-limiting step, thus exhibiting remarkably boosted bifunctional electrocatalytic ability with a low overpotential of 89 and 234 mV to drive a current density of 10 mA cm−2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline media, respectively. When the Mo-CoSe2 NS@NF electrode was employed as both a cathode and an anode, an advanced water electrolyzer was fabricated, and a 10 mA cm−2 water splitting current density in 1 M KOH solution could be acquired at a minimal cell voltage of 1.54 V. In addition, we also inferred that the active surface for the OER was O* covered CoSe2, and OER occurred through direct recombination mechanism according to the present first-principles simulation. This work offers an atomistic understanding on the boosted HER and OER electrocatalytical activity of CoSe2 by Mo doping, and develops a promising strategy for exploring advanced low-cost and earth-abundant water splitting electrocatalysts to substitute for the precious-metallic catalysts as well.

This paper presents an analytical model of the electromagnetic vibration and noise for a High Speed Amorphous Alloy Permanent Magnet Synchronous Motor (HSAAPMSM) whose stator cores are made from amorphous alloy magnetic material. Firstly, air gap flux density of HSAAPMSM with different slot width is calculated by two methods of Finite Element Analysis (FEA) and analytical. By comparison, accuracy of the modeling is validated. Then, through the finite element coupling analysis, the electromagnetic force acting on the surface of the stator teeth is obtained. In addition, the space harmonic analysis of air gap flux density and electromagnetic force is carried out. The electromagnetic vibration and noise of HSAAPMSM with different slot width are calculated respectively and the influence of laminating effect is taken into account.

This paper proposes a novel opposite-rotation dual-rotor axial flux permanent-magnet machine (ORDR-AFPM) for underwater vehicle counter-rotation propeller propulsion system. The structure of the machine mainly consists of dual identical surface-mounted PM rotors, dual sets of concentrated windings and single stator sandwiched in between the dual rotors. The dual rotors operate independently like dual conventional machines but toward opposite directions. For the purpose of exploring the interaction between the dual rotors and verify the feasibility of the machine, the flux distribution in the dual air gaps is analyzed by magnetic equivalent circuit (MEC). Meanwhile, finite-element method (FEM) is also used to confirm the validity of the theoretical analysis. During the process of machine design, the axial magnetic force is analyzed by using Maxwell stress tensor and the main design parameters of the machine get optimized.

According to the complexity of using two or more single DOF motors and links for two-degree-of-freedom (2-DOF) drive application, this paper presents a novel 2-DOF linear and rotary machine (LRM) as an electromagnetic actuator that can move in rotary and linear direction. Two units of the machine share the same unipolar permanent magnet stator, which can not only reduce the amounts of permanent magnets to save costs, but also shorten the axial length of the motor effectively on the basis of reducing the electromagnetic coupling between two parts of the actuator. The Linear and rotating armature windings and the unipolar permanent magnet stator of the actuator are designed comprehensively to obtain a reasonable electromagnetic scheme. Characteristics of the actuator are analyzed by Finite Element Analysis (FEA). As a result, the actuator meets the design requirements that 1Nm of the torque in rotary motion and the average thrust is 23.8 N in linear motion.

Platinum is the most active and commonly used electrocatalyst for hydrogen evolution reaction (HER). However, its expensive price and scarce supply limit its world-wide use for mass production of H2 by water electrolysis. Promising candidates for high-performance hydrogen evolution reaction with exceptionally low Pt loading are urgently required to obtain clean and sustainable chemical fuels. Herein, yolk-shell Pt-CoP polyhedra were prepared to realize low Pt loading on low-cost CoP polyhedral substrates via low-temperature calcination and phosphorization of ZIF-67 combined with a subsequent microwave-assisted platinum reduction process. Owing to the unique yolk-shell structure, large surface area, numerous active sites, trace Pt modification and improved conductivity, the resultant catalyst exhibits highly efficient electrocatalytic activities for the HER with the low overpotentials of only 48 mV and 88 mV at 10 mA cm-2 and excellent stability in the 1 M KOH and 1 M PBS solution, superior to most of the newly reported noble metal-based or transition metal-based catalysts, even the state-of-art Pt/C catalysts.

Owing to the hydrophobic inner cavity and hydrophilic exterior of cyclodextrins (CDs), CDs molecules could exhibit excellent properties in water solubility, molecular recognition and enrichment capability, and CDs-based materials attracted considerable attentions in electrochemical sensing. This review shows the unique advantages and detecting mechanism of electrochemical sensors based on CDs functionalized materials, and recent advances for CDs-based materials (including CDs/carbon nanotubes, CDs/graphene, CDs/conducting polymers and other CDs-based nanomaterials) in electrochemical sensing. Finally, we also discussed some critical challenges and prospects in this field.

The electrochemical properties of graphene-based supercapacitor electrode materials are closely related to their architecture and chemical nature. Herein, the siloxene-reduced graphene oxide composite hydrogel (SGH) with modified three-dimensional (3D) hierarchical architecture and increased oxygen-containing functional groups are developed via intercalating small amount of layered siloxene between the reduced graphene oxide sheets by a one-step hydrothermal process. Siloxene serves as the “spacers” to form a three-dimensional structure with graphene, resulting in increased specific surface area. More importantly, siloxene is used to modify the surface chemical nature of graphene sheets by introducing additional oxygen-containing functional groups. The abundant oxygen-containing functional groups on SGH contribute to the pseudocapacitance and improve the wettability. Consequently, the proposed SGH exhibits a high specific capacitance of 520 F g−1 at 1 A g−1 in a three-electrode system in 1 M H2SO4 electrolyte, which can be maintained for 76.9% even as the discharging current density increases up to 100 A g−1. Moreover, excellent stability is achieved for SGH with approximately 96.3% retention of the initial specific capacitance value after 15,000 cycles at a high current density of 50 A g−1. Furthermore, the assembled symmetrical supercapacitor of SGH//SGH delivers a high energy density of 24.5 Wh kg−1 at the power density of 399.6 W kg−1. These imply that the siloxene-reduced graphene oxide composite hydrogel may be a promising electrode material for high-performance supercapacitors.

Depended on the target-induced formation of a DNA-linked CdSe quantum dots/amino-functionalized graphene quantum dots (denoted as CdSe QDs/AGQDs) “Z-scheme” system, an ultrasensitive and highly selective PEC sensing platform has been constructed for DNA assay. Firstly, the indium tin oxide (ITO) electrode was modified with the poly(diallyldimethylammonium chloride) (PDDA)-decorated reduced graphene oxide (PDDA-rGO) to fix and disperse CdSe QDs. The obtained ITO/PDDA-rGO/CdSe QDs electrode generated an anode photocurrent. After catalytic hairpin assembly (CHA) and hybridization chain reaction (HCR) processes triggered by target DNA (T-DNA), abundant and long double-strand DNA (dsDNA) were introduced to the sensing platform. And then, numerous AGQDs were intercalated into the dsDNA strands, resulting in the formation of DNA-linked CdSe QDs/AGQDs “Z-scheme” system and the change of the response signal from anodic to cathode photocurrents. Because of the negative background signal and DNA-based amplification strategy, T-DNA was detected sensitively (linear range, 1 aM - 100 pM; detectable limit, 0.1 aM). Importantly, the developed PEC sensing platform can avoid the effects of the initial signal and background noise, and has the enhanced sensitivity and anti-interference ability, which make it may have promising application in bioanalysis and disease diagnosis.

DNA methylation catalyzed by M.SssI methyltransferases (MTase) has important roles in gene expression and other cellular activities, and relates to some diseases, especially cancers. Therefore, it is important to develop a sensitive sensing platform for M.SssI MTase activity assay. Here, taking zeolitic imidazolate framework-8 (ZIF-8) polyhedra as the carriers of graphene quantum dots (GQDs), GQDs-embedded ZIF-8 polyhedra (denoted as GQDs@ZIF-8 polyhedra) were successfully prepared and used as the multi-functional signal quencher to construct a novel signal-off photoelectrochemical (PEC) biosensor for M.SssI MTase activity assay. Firstly, the indium tin oxide (ITO) slice was modified with TiO2, poly(diallyldimethylammonium chloride) and CdTe quantum dots (QDs). The obtained electrode was used as the photoelectrode and labeled as ITO/TiO2/CdTe QDs. Then, single-stranded DNA (S1) was anchored on the photoelectrode surface via S-Cd bond. After hybridization between S1 and biotinylated single-stranded DNA (S2), the streptavidin (SA)-labeled GQDs@ZIF-8 polyhedra were introduced to the modified electrode via the specific reaction between biotin and SA. As the signal quencher, GQDs@ZIF-8 polyhedra could not only inhibit the photocurrent signal of the ITO/TiO2/CdTe QDs electrode due to the steric hindrance effect, but also act as peroxidase mimetics to catalyze precipitation reaction of 4-chloro-1-naphthol, resulting in the evident depression of the photocurrent signal. For the specially designed S1/S2 double-strand DNA, the decreased photocurrent was quantitatively correlated with the M.SssI MTase activity (linear response range, 0.005-150 U mL-1; detection limit, 0.004 U mL-1). The developed GQDs@ZIF-8 polyhedra and related PEC biosensor may have potential applications in clinical research and disease diagnosis.

Taking beta-cyclodextrin (β-CD) as reducting agent and dispersant, PtRh nanoparticles with varied metal composition were uniformly deposited on the β-CD functionalized carbon nanotubes (β-CD-CNTs) by one-pot hydrothermal synthesis method. Fourier transform infrared spectroscopy and thermogravimetric analysis were used to demonstrate the successful modification of CNTs with β-CD. The morphology, chemical composition and structure of the β-CD-CNTs supported PtRh catalysts (PtRh/β-CD-CNTs) have been characterized by transmission electron microscopy, X-ray diffraction and energy dispersive X-ray spectroscopy, respectively. Their electrochemical performances were investigated by typical electrochemical technologies. The results indicate that PtRh/β-CD-CNTs catalyst with 1:1 atomic ratio of Pt/Rh (Pt1Rh1/β-CD-CNTs) shows superior electrocatalytic properties towards methanol oxidation. In addition, compared with the acid-treatment CNTs (AO-CNTs) supported PtRh nanoparticles (PtRh/AO-CNTs) prepared by typical NaBH4 reduction, Pt1Rh1/β-CD-CNTs exhibits more excellent electrocatalytic performance for methanol electro-oxidation due to the smaller particle size and more uniform deposition of PtRh nanoparticles.

A ratiometric electrochemical sensor has been developed for highly sensitive and selective detection of bisphenol A. The assay strategy was based on the competitive host–guest interaction between poly- β -cyclodextrin/electroreduced graphene (P β -CD/EG) and Rhodamine B (RhB) probe or bisphenol A (BPA) target molecules. RhB can enter into the hydrophobic inner cavity of β -CD and shows an obvious oxidation peak on the P β -CD/EG modified glassy carbon electrode. In the presence of BPA, the RhB molecules are displaced by BPA because the host–guest interaction between β -CD and BPA is stronger than that between β -CD and RhB. As a result, the oxidation peak current of RhB ( I RhB ) decreases and the oxidation peak current of BPA ( I BPA ) increases correspondingly. The logarithmic value of I BPA / I RhB is linear with the logarithm of BPA concentration in the range of 1–6000 nM and the detection limit is 52 pM (S/N = 3). This strategy provides a new approach for sensitive detection of BPA, and has promising applications in the detection of organic pollutants in real environmental samples.

Based on the superior electrocatalytic property of graphene (GN) toward ascorbic acid (AA) oxidation, a new electrochemical aptasensor has been developed. Here, adenosine triphosphate (ATP) is used as the model to demonstrate the performance of the developed aptasensor. Briefly, GN is attached to the thiolated ATP binding aptamer (ABA) modified gold electrode through π-π stacking interaction, resulting in a significant oxidation signal of AA. In the presence of ATP, the formation of ATP-ABA complex leads to the release of GN from sensing interface, resulting in a sharp decrease of the oxidation peak current of AA and an obviously positive shift of the related peak potential. Taking both the change values of the peak current and peak potential of AA oxidation as the response signals, ATP can be detected sensitively. This is the first time to demonstrate the application of GN as the nanocatalyst in an amplified aptasensor. It can be expected that GN, as nanocatalyst, should become the very promising amplifying-elements in DNA-based electrochemical biosensors.

This paper presents a numerical heat transfer model for vertical U-tube Ground Heat Exchangers (GHE). This model is uniquely able to take into to account different initial soil temperatures and physical properties at different depths. The model has been validated based on an experimental case study and has been used to simulate the thermal performance of GHEs. The simulation results show that for a 100-m vertical GHE, the first 70 m of the vertically buried GHE has a higher heat transfer capability than its last 30-m section. In addition, the validated model is used to investigate the optimal depth of vertical GHEs in five case studies ranging from 60 to 100 m length. Among them, the simulation results demonstrate that the GHE with buried depth of 70 m is able to provide the highest heat exchange rate per unit depth (54.1 and 47.0 W/m under heat rejection/extraction mode). It consequently results in shortest total GHE length of 11,388 m and the minimum cost of 1.82 million Yuan. However, a larger area is needed for boreholes and GHEs installation. Therefore, the optimal buried depth of the vertical U-tube GHEs for the studied case is 70 m on the condition of allocation of an abundant area to set up the boreholes.

Because of its advantages such as large power density, small size and high efficiency, high-speed machine has been widely used in aerospace, industrial production and other fields. However, it is easy to cause irreversible permanent magnet demagnetization because of high density and difficult heat dissipation. In view of the above problems, the fluid field simulations of two ventilation systems are carried out, and a detailed fluid field analysis is carried out for the better middle ventilation system. High-speed permanent magnet machine rotor surface speed is very fast, resulting in the friction of the air can not be ignored. But its numerical value is related to many factors, such as machine speed, ventilation system, inlet wind velocity and surface roughness of the rotor. It is difficult to calculate accurately by analytic method. We simulated the 3D fluid model of rotor air friction loss and many factors influence on the high-speed permanent magnet machine is analyzed, and summarizes the corresponding high-speed permanent magnet machine rotor air friction loss law.

The external-rotor permanent magnet torque motor is widely used in electric vehicles and mobile robots. In order to improve its working accuracy, the cogging torque needs to be reduced. Cogging torque results from the interaction of permanent magnet magnetomotive force harmonics and air-gap permeance harmonics due to slotting. In this paper, the finite element analysis (FEA) has been conducted on the external-rotor surface-mounted permanent magnet motor. Cogging torque can be reduced by optimizing the shape of the permanent magnet (PM) according to the theoretical analysis. And three types of PM pole shape are adopt to reduce the cogging torque. By optimizing the dimension parameters of PMs, each of these three shapes can reduce the cogging torque effectively.

The direct feed system is prone to generate vibration due to insufficient damping in the direction of movement. In order to suppress the vibration of direct drive feed system, this paper presents a novel hybrid-excitated eddy current damper functioned as the damping compensation mechanism, which has non-contact mechanical structure and approximate linear damping characteristics. In this work, the characteristics of damper are investigated by Finite Element Analysis (FEA). The motion controller of the system was designed as a cascaded feedback structure with feedforward compensation. The control parameters are adjusted based on the identification of motor dynamic by the unbiased least square (ULS). Finally, the eddy current damper is installed in the motion direction of the direct drive feed system, and the vibration suppression experiments are implemented with 4.5g maximum acceleration. The results show that the root mean square value (RMS) value is reduced by 66% with the proposed method.

Based on the ultrasonic cavitation assisted hydrogen implosion method, Pt nanoparticles (NPs)/nitrogen-doped graphene nanohybrid scrolls (Pt NPs/N-GNSs) were synthesized. As the results of the N-doping and high reduction degree of graphene, and scroll structure of the nanohybrids, the Pt NPs/N-GNSs electrocatalyst shows excellent performance in the direct oxidation of methanol: low onset and peak potentials, high oxidation current, and good long-term cycle stability. The Pt NPs/N-GNSs should have great promising applications in heterogeneous catalysis and fuel cells.

In this paper, a new electrochemical method for the highly-selective determination of catechol (CC) has been fabricated based on the 3-aminophenylboronic acid-3,4,9,10-perylene tetracarboxylic acid functionalized carbon nanotubes (3-APBA–PTCA–CNTs) modified glassy carbon (GC) electrode. The 3-APBA–PTCA–CNTs hybrids and the related electrode were characterized by Fourier transform infrared spectroscopy, differential pulse voltammetry and electrochemical impedance spectroscopy. Due to the highly-selective bonding of 3-APBA with 1,2-diols to form a pinacol ester, the 3-APBA–PTCA–CNTs/GC electrode showed high selectivity for the determination of CC from dihydroxybenzene isomers with a linear response range of 0.5 to 30 μM and a detection limit of 0.1 μM (S/N = 3). Furthermore, the developed 3-APBA–PTCA–CNTs/GC electrode was successfully applied to selectively detect CC in local river water samples with the co-existence of hydroquinone (HQ), CC and resorcinol (RE).

The inductive reaction sphere (RS) brings the benefit of simple, economical, and miniaturized design, and it is capable of multi-DOF torque generation. Thus, it is a suitable choice for the angular momentum exchange actuator in attitude control of micro-spacecrafts. To synthesize symmetric distribution of eddy currents and improve the speed and stability of rotation, a novel 4-pole winding design is proposed. However, the developed simplified analytical model shows that reduced pole number degrades the torque generation. To enhance the output torque of 4-pole RS, its curved cores and electromagnets are redesigned to enable the side teeth to be functional. As the analytical torque model for the RS with the slotted cores is not available, a constrained optimization problem is formulated, and the optimized parameters are calculated based on the prediction model from supported vector machine and finite element analysis. The lab prototypes are developed to validate the proposed design and test the speed performance. The experimental results show that the 4-pole RS prototype obtains a stable rotation over 700 rpm about X, Y and Z axis respectively with the angular momentum of 0.08 kg·m 2 /s, being superior to the 6-pole counterpart.

Objectives In a variety of experimental models, propofol has been shown to protect the brain. It was hypothesized that a clinically achievable high dose of propofol would induce cerebral protective effects in patients undergoing cardiac surgery with cardiopulmonary bypass (CPB). The authors investigated the effects of different target plasma concentrations of propofol on cerebral injury by measuring serum S-100β protein and neuron-specific enolase (NSE) levels in patients undergoing single-valve replacement with CPB. Design A prospective, randomized study. Setting A university hospital. Participants Forty-two patients undergoing single-valve replacement with CPB. Interventions Patients were randomly divided into 3 groups (n = 14 each). Each group received a target-controlled infusion of propofol with plasma concentrations of 1.8 μg/mL (low dose, Group-L), 2.4 μg/mL (medium dose, Group-M), or 3.2 μg/mL (high dose, Group-H). The propofol target concentrations were unchanged throughout the surgery. Measurements and Main Results In all 3 groups of patients, at all time points after CPB, the plasma S-100β protein and NSE levels, which served as biochemical markers of brain damage, were significantly higher than the preoperative levels (p Conclusion In the range of commonly used clinical concentrations, administration of a high dose of propofol during CPB attenuated the biochemical markers of brain damage as compared with low-dose propofol anesthesia.

Based on the competitive host-guest interaction between a β-cyclodextrin/poly(N-acetylaniline)/electrogenerated-graphene (β-CD/PNAANI/EG) film and probe or target molecules, a new dual-signalling electrochemical sensing method has been developed for the sensitive and selective determination of organic pollutants. As a model system, rhodamine B (RhB) and 1-aminopyrene (1-AP) were adopted as the probe and target molecules, respectively. Due to the host-guest interaction, RhB molecules can enter into the hydrophobic inner cavity of β-CD, and the β-CD/PNAANI/EG-modified glassy carbon electrode displays a remarkable oxidation peak due to RhB. In the presence of 1-AP, competitive association to β-CD occurs and the RhB molecules are displaced by 1-AP. This results in a decreased oxidation peak current of RhB and the appearance of an oxidation peak current for 1-AP, and the changes of these signals correlate linearly with the concentration of 1-AP. When the value ΔI(1-AP)+∣ΔI(RhB)∣ (ΔI(1-AP) and ΔI(RhB) are the change values of the oxidation peak currents of 1-AP and RhB, respectively) is used as the response signal to quantitatively determine the concentration of 1-AP, the detection limit is much lower than that given by using ΔI(1-AP) or ΔI(RhB) as the response signal. This dual-signalling sensor can provide more sensitive target recognition and will have important applications in the sensitive and selective electrochemical determination of electroactive organic pollutants.

A novel eddy current damper with hybrid excitation is presented in this paper. The eddy current damper contains two hybrid excitation components and a moving conductor plate. The hybrid excitation component is consisted of primary coil, the primary iron core and permanent magnet. The conductor plate is sandwiched between two excitation components. Analyses of the proposed damper are conducted with analytical method and FEA respectively. The analysis results validate the feasibility of the design and the correctness of the developed analytical model. The optimization method of the damping effect is studied based on numerical computation with the employment of the Taguchi optimization method. The simulation results stated that the damping force was increased by 32.16% with the proposed method.

This paper introduces three-type voice coil motors (VCMs) for nano-positioning system. These VCMs all consists dual-magnet stator and coil mover which is sandwiched between these two-layer magnets with different topology structures of the stators and movers. The motor structures, magnetic field distribution, thrust force and force ripple of these VCMs are studied and compared. Equivalent magnetic circuit method and the finite element analysis (FEA) are employed to analyze the performance of these VCMs. The results show that the VCM with Halbach array permanent magnets and three-segment coil mover has the largest force constant and smallest force ripple. A prototype of the Halbach VCM is manufactured and tested. The experimental results accord well with which of the simulation.

This paper proposes a recovery control strategy of a two-stroke free-piston linear generator. The recovery process is implemented through switching the linear electric machine into motoring mode once certain unstable operation like misfire occurs during stable cycles. Various operation states are illustrated. Both the steady operation strategy and the fault recovery strategy are analyzed and simulated. The analysis experiments results show that the proposed recovering strategy is feasible and easy to be implemented. The unstable situation can be effectively recovered during 20ms or less, and has no negative influence on the next stable operation.

This paper is aimed at studying the breakdown voltage and minimum ignition energy of sparking system for the free-piston linear generator (FPLG). Combing the ignition characteristics and demands specifically for the FPLG system, the breakdown voltage and conduction duration of the primary coil are determined theoretically with the Townsend and Paschen Laws. A computational fluid dynamics (CFD) mode is developed to investigate the in-cylinder pressure and temperature at various igniting moments. The theoretical minimum ignition energy is determined with the laminar combustion theory, which contributes to the design and optimization of the sparking system. The effects of the ignition points and initial in-cylinder temperature on the breakdown voltage and minimum ignition energy are analyzed. The results show that advanced ignition contributes to decreasing the breakdown voltage and the conduction duration of the primary coil, meanwhile has no negative influence on the minimum ignition energy. However, rising initial in-cylinder temperature lowers the breakdown voltage, shortens the conduction duration of the primary coil and reduces the minimum ignition energy.

Based on the theoretical and experimental studies of natural ventilation, the performance of natural ventilators has been analysed. Four types of natural window ventilators and three types of wall ventilators were studied. Experimental results show that the natural ventilators have a greater ventilation effect whilst meeting national and local standards of ventilation for residential buildings in heating or cooling seasons. The installation of such devices can be a compromise between ventilation and energy loss. Compared with natural window ventilators, wall ventilators are more efficient. The discharge coefficients of the ventilators were calculated, which can guide the design of natural ventilation for residential buildings. However, these coefficients are small on the whole, which indicates that the structure and design of ventilators should be improved because ventilators still have large resistances to airflow. The CO2 concentrations in a room with different numbers of ventilators were calcul...

Polythiophene (PTh) was electropolymerized onto multi-walled carbon nanotubes (MWCNT) modified glassy carbon (GC) electrode in ionic liquid bmimPF6 solution successfully. The different electrochemical behavior of thiophene in bmimPF6 solution was studied by cyclic voltammetry. The different morphologies of PTh films on MWCNT/GC and GC electrodes were characterized by scanning electron microscopy. Cyclic voltammetry test displays that PTh/MWCNT composites have better capacitive property than pure MWCNT and pure PTh. The galvanostatic charge–discharge and electrochemical impedance microscopy tests show that the PTh/MWCNT composites possess good capacitive characteristics. The specific capacitance of the supercapacitor is 110 F g−1. The long-term stability of the supercapacitor was also tested, and the result indicates that the specific capacitance still keeps 90% of the initial capacitance after 1000 consecutive charge–discharge cycles.

A facile method for one-pot synthesis of highly dispersed palladium nanoparticles on acetylenic ionic liquid polymer functionalized carbon nanotubes (PdNPs-AILP-CNTs) has been developed in this paper. The nanohybrids are prepared by polymerization of acetylenic ionic liquid monomers catalyzed by PdCl2, which is further reduced to PdNPs by NaBH4 on CNTs in one pot and characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, thermogravimetric analysis, and transmission electron microscopy. The electrocatalytic oxidation of glucose on the PdNPs-AILP-CNT nanohybrids is also investigated by cyclic voltammetry and chronoamperometry. The results show that the PdNPs with a particle size of around 3.5 nm disperse uniformly on CNTs, and PdNPs-AILP-CNT nanohybrids have good electrocatalytic performance for glucose oxidation.

Summary We briefly review the recent advances in the synthesis of noble metal nanoparticles/carbon nanotubes nanohybrids and their applications in heterogeneous catalysis, fuel cells, and chemo/biosensors.

A new kind of supercapacitor by using chemical reduced graphene (CRG) as electrode material and ionic liquid with addition of acetonitrile as electrolyte is assembled and investigated. CRG materials with high surface area are prepared by chemical reduction of graphene oxide. The capacitive properties of the supercapacitor composed of the CRG and ionic liquid electrolyte are studied by electrical impedance spectroscopy, cyclic voltammetry and galvanostatic charge–discharge. With the combined advantages of graphene and ionic liquid, the supercapacitor shows perfect performance. The supercapacitor possesses wide cell voltage and good stability. The specific capacitance, energy density, and specific power density of the present supercapacitor are 132 Fg−1, 143.7 Wh kg−1, and 2.8 kW kg−1, respectively. The results demonstrate the potential application of electrical energy storage devices with high performance based on this new kind of supercapacitor.

Graphene oxide (GO) and Au(Ш) are electrochemically co-reduced in ionic liquid to prepare graphene/Au nanocomposites. The electrochemical reduction processes were recorded by I–t curves, which indicate that the simultaneous reduction of GO and Au(Ш) is favorable to each other. The X-ray diffraction patterns confirm the complete reduction of GO. The scanning electron microscopy and transmission electron microscopy results reveal that Au particles with a diameter of about 10 nm are dispersed uniformly on the electrochemically reduced graphene (ER-G). Furthermore, the electrochemical activity of ER-G/Au nanocomposites was evaluated and the ER-G/Au nanocomposites electrode demonstrates great electrochemical catalytic activity and stability.

The bimetallic Ag/Au nanoparticles were prepared by underpotential deposition-redox replacement technique on the basis of Au nanoparticles modified glassy carbon (GC) electrode. The as-prepared Ag/Au nanoparticles were characterized by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The Ag/Au bimetallic nanoparticles modified GC electrode with low-Ag loading exhibits much better catalytic activity for the reduction of benzyl chloride than Ag nanoparticles modified GC electrode. The result is attributed to the synergic effect between Ag and Au in the reduction process. The chronoamperometry test shows that the Ag/Au nanoparticles possess long-term performance in the electrolysis. Keywords: Bimetallic, Nanoparticles, Underpotential deposition, Electroreduction, Benzyl chloride

Graphene nanosheets, synthesized by a modified Hummers method, have been functionalized by PMo12, and used as the supports of the PtRu nanoparticles. The electrocatalytic properties of the resultant nanocatalysts (PtRu/PMo12-Graphene) for methanol electro-oxidation have been evaluated by cyclic voltammetry and chronoamperometry. The micrograph and the elemental composition have also been investigated by transmission electron microscopy and energy dispersive X-ray spectroscopy. The results suggest that the addition of PMo12 benefits the high dispersion of graphene nanosheets in the water and the uniform dispersion of the PtRu nanoparticles on the graphene nanosheets, and the PtRu/PMo12-Graphene catalysts have higher electrocatalytic activity and better electrochemical stability for methanol oxidation compared to the PtRu/Graphene catalysts.

Two kinds of functionalized graphene sheets were produced by thermal exfoliation of graphite oxide. The first kind of functionalized graphene sheets was obtained by thermal exfoliation of graphite oxide at low temperature in air. The second kind was prepared by carbonization of the first kind of functionalized graphene sheets at higher temperature in N2. Scanning electron microscopy images show that both two kinds of samples possess nanoporous structures. The results of N2 adsorption–desorption analysis indicate that both of two kinds of samples have high BET surface areas. Moreover, the second kind of functionalized graphene sheets has a relatively higher BET surface area. The results of electrochemical tests is as follows: the specific capacitance values of the first kind of functionalized graphene sheets in aqueous KOH electrolyte are about 230 F g−1; the specific capacitance values of the second kind of functionalized graphene sheets with higher BET surface areas are only about 100 F g−1; however, compared with the first kind of functionalized graphene sheets, the second kind has a higher capacitance retention at large current density because of its good conductive behaviors; furthermore, in non-aqueous EC/DEC electrolyte, the specific capacitance values of the first kind sample and the second kind sample are about 73 F g−1 and 36 F g−1, respectively.

A new amperometric glucose biosensor has been developed based on platinum (Pt) nanoparticles/polymerized ionic liquid-carbon nanotubes (CNTs) nanocomposites (PtNPs/PIL-CNTs). The CNTs was functionalized with polymerized ionic liquid (PIL) through directly polymerization of the ionic liquid, 1-vinyl-3-ethylimidazolium tetrafluoroborate ([VEIM]BF 4 ), on carbon nanotubes and then used as the support for the highly dispersed Pt nanoparticles. The electrochemical performance of the PtNPs/PIL-CNTs modified glassy carbon (PtNPs/PIL-CNTs/GC) electrode has been investigated by typical electrochemical methods. The PtNPs/PIL-CNTs/GC electrode shows high electrocatalytic activity towards the oxidation of hydrogen peroxide. Taking glucose oxidase (GOD) as the model, the resulting amperometric glucose biosensor shows good analytical characteristics, such as a high sensitivity (28.28 μA mM −1 cm −2 ), wide linear range (up to 12 mM) and low detection limit (10 μM).

Small beginnings: Metal nanoparticle/CNT nanohybrids are synthesized from carbon nanotubes (CNTs) functionalized with an ionic-liquid polymer. The Pt and PtRu nanoparticles with narrow size distribution (average diameter: (1.3+/-0.4) nm for PtRu, (1.9+/-0.5) nm for Pt) are dispersed uniformly on the CNTs (see images) and show good performance in methanol electrooxidation.