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In order to improve the performance of the active vibration isolation system (AVIS) with electromagnetic actuator, several problems of vibration control are studied. Position control is a critical component in suspension systems, and the position sensor noise can extremely affect the stability of the system, so a tracking differentiator (TD) is proposed to obtain effective differential signal from relative position sensor. In vibration control, the feedback of acceleration combined with PD position feedback is presented to suppress transmission of periodic vibrations. Then, taking the acceleration transmission as the evaluation index, the acceleration transmission under the presented control method is derived, and the influence of control parameters on vibration isolation performance is discussed in detail. The vibration isolation performance is improved from 24.47 dB to 2.4 dB at resonance frequency, and −34 dB attenuation is achieved at 100 Hz with respect to vibration isolation mount system tested on the ground. The experimental results demonstrate that the performance of active vibration isolation system are improved by the proposed acceleration feedback control.

The colour centre platform holds promise for quantum technologies, and hexagonal boron nitride has attracted attention due to the high brightness and stability, optically addressable spin states and wide wavelength coverage discovered in its emitters. However, its application is hindered by the typically random defect distribution and complex mesoscopic environment. Here, employing cathodoluminescence, we demonstrate on-demand activation and control of colour centre emission at the twisted interface of two hexagonal boron nitride flakes. Further, we show that colour centre emission brightness can be enhanced by two orders of magnitude by tuning the twist angle. Additionally, by applying an external voltage, nearly 100% brightness modulation is achieved. Our ab initio GW and GW plus Bethe-Salpeter equation calculations suggest that the emission is correlated to nitrogen vacancies and that a twist-induced moiré potential facilitates electron-hole recombination. This mechanism is further exploited to draw nanoscale colour centre patterns using electron beams.

Rigid, solid-state components represent the current paradigm for electronic systems, but they lack post-production reconfigurability and pose ever-increasing challenges to efficient end-of-life recycling. Liquid electronics may overcome these limitations by offering flexible in-the-field redesign and separation at end-of-life via simple liquid phase chemistries. Up to now, preliminary work on liquid electronics has focused on liquid metal components, but these devices still require an encapsulating polymer and typically use alloys of rare elements like indium. Here, using the self-assembly of jammed two-dimensional titanium carbide (Ti

The low mass density and high mechanical strength of graphene make it an attractive candidate for suspended-membrane energy transducers. Typically, the membrane size dictates the operational frequency and bandwidth. However, in many cases it would be desirable to both lower the resonance frequency and increase the bandwidth, while maintaining overall membrane size. We employ focused ion beam milling or laser ablation to create kirigami-like modification of suspended pure-graphene membranes ranging in size from microns to millimeters. Kirigami engineering successfully reduces the resonant frequency, increases the displacement amplitude, and broadens the effective bandwidth of the transducer. Our results present a promising route to miniaturized wide-band energy transducers with enhanced operational parameter range and efficiency.

The photocatalytic CO

In order to accurately predict the key dangerous parts of the polygonal pressure pipeline in a corrosive environment, based on the stress fatigue theory, a stainless steel pipeline damage calculation model coupled with the coupling of fatigue and corrosion is established, and the cold and operating conditions are carried out for the polygonal pressure pipeline. The analysis of stress and damage fields shows that the fatigue life of the square-shaped pipeline is reduced from 9225 to 42 years after the influence of the stress concentration factor of pitting corrosion. Based on the results of the damage analysis, by defining the dangerous concentration parameters, it is predicted that the key dangerous parts of the zigzag pressure pipeline are mainly the elbow and the long side abdomen. The greater the dangerous concentration parameter is, the more concentrated the dangerous parts are. When the dangerous concentration parameter is greater than 0.5, the elbow of the pipe shoulder and the long side joint are not critical dangerous parts anymore.

Constructing direct Z-scheme system is a promising strategy to boost the photocatalytic performance for pollution waters restoration, but it is of great challenge because of the requirement of appropriately staggered energy band alignment and intimate interfacial interaction between semiconductors. Herein, a class of core-shell structured Ag

The pursuing of photosensitizers (PSs) with efficient reactive oxygen species (ROS) especially type I ROS generation in aggregate is always in high demand for photodynamic therapy (PDT) and photoimmunotherapy but remains to be a big challenge. Herein, we report a cationization molecular engineering strategy to boost both singlet oxygen and radical generation for PDT. Cationization could convert the neutral donor-acceptor (D-A) typed molecules with the dicyanoisophorone-triphenylamine core (DTPAN, DTPAPy) to their A-D-A′ typed cationic counterparts (DTPANPF6 and DTPAPyPF6). Our experiment and simulation results reveal that such cationization could enhance the aggregation-induced emission (AIE) feature, promote the intersystem crossing (ISC) processes, and increase the charge transfer and separation ability, all of which work collaboratively to promote the efficient generation of ROS especially hydroxyl and superoxide radicals in aggregates. Moreover, these cationic AIE PSs also possess specific cancer cell mitochondrial targeting capability, which could further promote the PDT efficacy both in vitro and in vivo. Therefore, we expect this delicate molecular design represents an attractive paradigm to guide the design of type I AIE PSs for the further development of PDT.

Conjugated polymers have recently been under active investigation as promising alternatives to traditional inorganic semiconductors for photocatalysis. This is due to their unique advantages of low cost, high chemical stability, and molecularly tunable optoelectronic properties. This critical review summarizes the recent advancements in π-conjugated polymers for visible-light-driven photocatalytic applications including water splitting, CO2 reduction, organic transformation and degradation of organic dyes. Special emphasis is placed on how the changes in the polymer structure could influence their physicochemical properties and photocatalytic activities. This structure–activity relationship analysis should guide rational molecular design of conjugated polymers for improved photocatalytic activity.

Current graphene-based plasmonic devices are restricted to 2D patterns defined on planar substrates; thus, they suffer from spatially limited 2D plasmon fields. Here, 3D graphene forming freestanding nanocylinders realized by a plasma-triggered self-assembly process are introduced. The graphene-based nanocylinders induce hybridized edge (in-plane) and radial (out-of-plane) coupled 3D plasmon modes stemming from their curvature, resulting in a four orders of magnitude stronger field at the openings of the cylinders than in rectangular 2D graphene ribbons. For the characterization of the 3D plasmon modes, synchrotron nanospectroscopy measurements are performed, which provides the evidence of preservation of the hybridized 3D graphene plasmons in the high precision curved nanocylinders. The distinct 3D modes introduced in this paper, provide an insight into geometry-dependent 3D coupled plasmon modes and their ability to achieve non-surface-limited (volumetric) field enhancements.

The relative position sensor of a high-speed maglev train is an important part of train location and speed detection for motor traction, but its output signal is not only related to position but also related to the suspension gap of the maglev train. The fluctuation of the suspension gap will affect the amplitude of the output signal of the sensor (i.e., the suspension wave signal is coupled with the output signal). The prediction normalization method currently used can eliminate the effect of the suspension fluctuation to a certain extent, but there is a limitation. Aiming at this problem, this paper analyzes the frequency characteristics of the suspension gap fluctuation caused by track irregularities and proposes a gap estimation algorithm based on the adaptive filter. The Kalman filter is used to estimate the gap and then the output signal is compensated according to the numerical relationship between the gap and the output signal of the sensor, so as to achieve the decoupling between the gap and the position measurement. Finally, the effectiveness of the method is proved by the comparison experiments.

Organic π-conjugated polymers (CPs) have been intensively explored for a variety of critical photocatalytic applications in the past few years. Nevertheless, CPs for efficient CO2 photoreduction have been rarely reported, which is mainly due to the lack of suitable polymers with sufficient solar light harvesting ability, appropriate energy level alignment and good activity and selectivity in multi-electron-transfer photoreduction of CO2 reaction. We report here the rational design and synthesis of two novel triphenylamine (TPA) based conjugated microporous polymers (CMPs), which can efficiently catalyze the reduction of CO2 to CO using water vapor as an electron donor under ambient conditions without adding any co-catalyst. Nearly 100% selectivity and a high CO production rate of 37.15 μmol h−1 g−1 are obtained for OXD-TPA, which is significantly better than that for BP-TPA (0.9 μmol h−1 g−1) as a result of co-monomer change from biphenyl to 2,5-diphenyl-1,3,4-oxadiazole. This difference could be mainly ascribed to the synergistic effect of a decreased optical band gap, improved interface charge transfer and increased CO2 uptake for OXD-TPA. This contribution is expected to spur further interest in the rational design of porous conjugated polymers for CO2 photoreduction. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) Accepted version

In marine nuclear power plants based on molten salt reactors, the complexity of core nuclear reactions, fuel fluidity, and the “false” water level characteristics of the steam generator water level make it unrealistic to establish an accurate mathematical model, so it is difficult to implement traditional PID control methods. This has increased substantially. The fuzzy control has a good solution to this feature. Therefore, combined with the fuzzy control that does not depend on the precise mathematical model of the controlled object, the fuzzy controller of the nuclear power plant is designed, and the control research of the core power is obtained respectively through MATLAB/Simulink simulation. It shows that the designed fuzzy controller can achieve good control of nuclear power plants.

Within a total residence time of 9 min, the sodium salt of ciprofloxacin was prepared from simple building blocks via a linear sequence of six chemical reactions in five flow reactors. Sequential offline acidifications and filtrations afforded ciprofloxacin and ciprofloxacin hydrochloride. The overall yield of the eight‐step sequence was 60 %. No separation of intermediates was required throughout the synthesis when a single acylation reaction was applied to remove the main byproduct, dimethylamine., United States. Defense Advanced Research Projects Agency (Grant N666001-11-C-4005)

A series of Sn2+ doped MgIn2S4 photocatalysts were prepared via a facial hydrothermal method. The Sn dopants substitute the sites of Mg atom in MgIn2S4 unit cell, but not alter the crystal structure, demonstrated by the results of XRD and XPS. Compared to pristine MgIn2S4, Sn-doped MgIn2S4 samples exhibit significantly enhanced photocatalytic CO2 reduction activity. With increasing the Sn dopant content, the CO2 conversion rate first ascends, achieving the maximum rate at Sn-MgIn2S4-2 sample, and then decreases. After illumination for 4 h, the highest yield of CO and CH4 for Sn-MgIn2S4-2 sample reaches about 3.35 and 3.33 times higher than that of pristine MgIn2S4. The theoretical results based on density functional theory calculations reveal that Sn doping in MgIn2S4 tunes the band structure from the direct-transition of MgIn2S4 to indirect-transition, diminishes band gap and extends the light absorption range, reduces the effective masses of holes and promotes the migration of photoinduced carriers. The experimental results also demonstrate the positive role of Sn dopant in accelerating the separation and transportation of charges, and improving CO2 adsorption ability. This work systematically investigates and discusses the Sn2+ doping effect in MgIn2S4 on crystal structure, lattice variations, electronic band structures, CO2 adsorption ability, and photocatalytic CO2 reduction activity, which can provide a new hint for the fabrication of efficient photocatalyst by metal ion doping.

The numerical simulation analysis of the fluid-solid coupling of the ship’s boring water-lubricated bearing is carried out to study the influence law of the inclination and eccentricity of the rotating shaft on the pressure distribution and fluid flow state in the bearing. The results show that the tilt of the rotating shaft changes the shape of the inner flow passage of the water-lubricated bearing, resulting in unstable flow in the bearing. When rotating shaft is in normal, the pressure value in the water-lubricated bearing decreases first and then increases in the axial direction. However, after the rotation of the shaft is tilted, the change of the pressure value is the opposite; the stress of the rubber layer generally shows an increasing trend with the increase of the inclination angle.

Photoelectrochemical water splitting over semiconductors offers a sustainable solar light conversion technique capable of alleviating worldwide energy crisis. Conjugated polymers have recently received increasing attention as a class of promising photoelectrode materials due to their advantages of earth-abundance, non-toxicity, light weight, and molecularly tunable functionalities, etc. However, the development of highly efficient organic photoelectrodes remains a big challenge. In this study, two covalent organic frameworks (COFs) incorporated 2,4,6-triphenyl-1,3,5-triazine are demonstrated as excellent photocathodes for H production. By introducing 2,4,6-triphenylbenene to properly create donor/acceptor pairs within COF, a significantly enhanced visible-light photocurrent of TAPB-TTB COF (110 µA cm ) compared to TTA-TTB COF (35 µA cm ) at 0 V versus reversible hydrogen electrode (RHE) is obtained without adding organic sacrificial agent and metal cocatalysts (>420 nm). The enhanced photocurrent density is attributed to the narrowed bandgap and improved charge transfer by intramolecular donor–acceptor combination. This work highlights the great promising applications of crystalline donor–acceptor COFs as high-efficiency organic photoelectrode for water splitting. Ministry of Education (MOE) National Research Foundation (NRF) Accepted version Financial work was provided by the Singapore National Research Foundation (grant no. R279-000-444-281), the National 11 University of Singapore (grant no. R279-000-482-133), Research Foundation for Advanced Talents of East China University of Technology (No. DHBK201927), National Science Foundation for Young Scientists of China (grant no. 21905122), National Science Foundation of Jiangxi province of China (No. 20202BAB203007). D. J. acknowledges supports by MOE tier 1 grant (R-143-000-A71-114) and NUS start-up grant (R-143-000-A28-133). C. X. thanks the support from the Ministry of Education, Singapore, under AcRF-Tier2 (MOE2018-T2-1- 017) and AcRF-Tier1 (MOE2019-T1-002-012, RG102/19).

Binary metal oxides have been considered as promising anode materials, which exhibit much better performances than single metal oxides in view of their variable oxidation state and fairly high electrical conductivity. In this research, NiCo2O4 nanocrystals are prepared from a facile procedure including microemulsion-solvothermal reaction and subsequent calcination at 400 °C for 4 hours. The as-prepared NiCo2O4 nanocrystals are characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). When applied as an anode for a lithium ion battery, it demonstrates excellent cycling and rate stability. The initial charge/discharge efficiency is as high as 75.41% at a current density of 100 mA g−1. After 45 cycles, the discharge capacity still retains up to 1175.9 mA h g−1, which is even much higher than that of the initial discharge capacity. Meanwhile, the reversible capacity remains over 644.9 mA h g−1 at a large current density of 1600 mA g−1, ascribed to the dispersed nanoparticles, which will help to improve the conductivity of the electrode material during the lithium-ion insertion/deintercalation process, shorten the ion diffusion path and reduce the charge transfer resistance (Rct).

Cleavage of carbon–halogen bonds via either single-electron reduction or atom transfer is a powerful transformation in the construction of complex molecules. In particular, mild, selective hydrodehalogenations provide an excellent follow-up to the application of halogen atoms as directing groups or the utilization of atom transfer radical addition (ATRA) chemistry for the production of hydrocarbons. Here we combine the mechanistic properties of photoredox catalysis and silane-mediated atom transfer chemistry to accomplish the hydrodebromination of carbon–bromide bonds. The resulting method is performed under visible light irradiation in an open vessel and is capable of the efficient reduction of a variety of unactivated alkyl and aryl substrates.

This paper presents a double-tube once-through steam generator (DOTSG), whose tube unit includes an outer straight tube and an inner helical tube, in an integral pressurized water reactor (IPWR). To obtain the optimum structure of the inner helical tube and the arrangement of DOTSGs in the reactor pressure vessel, a two-level optimization method is used, aiming at the lower pumping power needed, and a smaller reactor pressure vessel volume is used. The pitch of inner helical tubes and the central distance of outer tubes are considered design parameters when minimizing the pumping power with the genetic algorithm in the bottom level, while the number of tube units in a single DOTSG and the number of DOTSGs in the reactor pressure vessel (RPV) are optimized to obtain the minimum volume of the IPWR, which is conducted in the top level. The optimum pitch of the helical tube varies in the sub-cooled region, boiling region and superheated region. The results show that the smaller pitch brings a shorter tube length and a higher pressure drop, and the effects are strong in the sub-cooled region and the superheated region but weak in the boiling region. In this way, the optimal structure of the inner helical tube is a small pitch in the single-phase region and a large pitch in the boiling region. According to the bottom level results, the optimum arrangement of DOTSGs in the pressure vessel is determined.

In order to improve the efficiency of ship pipeline vibration isolation, an optimized design scheme of coated rubber vibration isolator was proposed. The natural frequency was calculated and a test bench was established for vibration isolation performance test. The results show that the dynamic and static stiffness of the optimized vibration isolator is significantly lower than the traditional design value at the natural frequency. The natural frequency of the vibration isolator is reduced from about 35Hz to about 9.7Hz from the initial design scheme, and the vibration isolation efficiency is increased from about 20dB to about 33dB as well.

Pre-treatment of graphitic carbon nitride (GCN) with H2O2 introduces active C–OH groups that can react with HAuCl4 to immobilize single atom Au(I) in the GCN matrix through creating robust Au(I)–O coordination bonds. This strong bonding can effectively restrict the diffusion of intermediate Au(0) towards the formation of Au particles during the photocatalytic hydrogen evolution process. As such, the single atom Au(I) incorporated GCN maintained superior activities with excellent stabilities for photocatalytic hydrogen generation. Accepted version

Conjugated polymer-based photocatalysts have shown great potential in H2 production via water splitting, but an intrinsic drawback of conventional hydrophobic polymer photocatalysts is their poor wettability and relatively large particle size in aqueous media, which is favorable for charge recombination with limited interfacial reaction efficiency. Herein, a well-dispersed organic water reduction system using cationic conjugated polyelectrolyte as the photocatalyst has been reported for the first time. In comparison to a model polymer (PFBT) bearing the same conjugated backbone, the polyelectrolyte exhibits significantly enhanced photocatalytic efficiency due to the extended light absorption and improved charge separation of the polymer aggregates. Ministry of Education (MOE) National Research Foundation (NRF) Accepted version This work was financially supported by the Singapore National Research Foundation (R279-000-444-281 and R279-000-483-281), National Univer- sity of Singapore (R279-000-482-133), Singapore MOE AcRF-Tier1 (RG 12/15), Singapore MOE AcRF-Tier1 (2016-T1-002-087, RG 120/16), and AcRF-Tier2 (MOE2016-T2-2-056).

The assembly of two-dimensional (2D) graphene into three-dimensional (3D) polyhedral structures while preserving the graphene's excellent inherent properties has been of great interest for the development of novel device applications. Here, fabrication of 3D, microscale, hollow polyhedrons (cubes) consisting of a few layers of 2D graphene or graphene oxide sheets via an origami-like self-folding process is described. This method involves the use of polymer frames and hinges, and aluminum oxide/chromium protection layers that reduce tensile, spatial, and surface tension stresses on the graphene-based membranes when the 2D nets are transformed into 3D cubes. The process offers control of the size and shape of the structures as well as parallel production. In addition, this approach allows the creation of surface modifications by metal patterning on each face of the 3D cubes. Raman spectroscopy studies show the method allows the preservation of the intrinsic properties of the graphene-based membranes, demonstrating the robustness of our method.

Three dibenzothiophene-S,S-dioxide-based alternating copolymers were synthesized by facile Suzuki polymerization for visible light-responsive hydrogen production from water (> 420 nm). Without addition of any cocatalyst, FluPh2-SO showed a photocatalytic efficiency of 3.48 mmol h-1 g-1 , while a larger hydrogen evolution rate (HER) of 4.74 mmol h-1 g-1 was achieved for Py-SO, which was ascribed to the improved coplanarity of the polymer that facilitated both intermolecular packing and charge transport. To minimize the possible steric hindrance of FluPh2-SO by replacing 9,9'-diphenylfluorene with fluorene, Flu-SO exhibited a more red-shifted absorption than FluPh2-SO and yielded the highest HER of 5.04 mmol h-1 g-1 . This work highlights the potential of dibenzothiophene-S,S-dioxide as a versatile building block and the rational design strategy for achieving high photocatalytic efficiency. NRF (Natl Research Foundation, S’pore) ASTAR (Agency for Sci., Tech. and Research, S’pore) MOE (Min. of Education, S’pore)

A filtering algorithm and direction identification method are presented for the positioning system of the mid-speed maglev train. Considering the special structure of the mid-speed maglev train, the ground position estimation method is adopted for its traction system. As the train is running, the induction loop-cable receives the signal sent by the on-board antenna to detect the position and direction of the train. But the height of the on-board antenna relative to the loop-cable is highly vulnerable to the change of the suspension height and the magnetic field produced by the traction during traveling, which may lead to amplitude fluctuation of the received signal. Consequently, the position estimation may be inaccurate. Therefore, a discrete second-order nonlinear trackdifferentiator is proposed based on the boundary characteristic curves, and the new differentiator could also extract the running direction of the train for the traction system. The experimental results show that the tracking differentiator can effectively filter out the signal interference and can provide accurate direction signal.

Flow chemistry has attracted significant interest in pharmaceutical development, where substantial efforts have been directed toward the design of continuous processes. Here, we report a total synthesis of atropine in flow that features an unusual hydroxymethylation and separation of several byproducts with high structural similarity to atropine. Using a combination of careful pH control in three sequential liquid-liquid extractions and a functionalized resin, atropine is delivered by the flow system with >98% purity., United States. Defense Advanced Research Projects Agency (DARPA N66001-11-C-4147)

Three conjugated polymers (CPs) bearing a common fluorene-dibenzothiophene-S,S-dioxide backbone were designed and synthesized for photoelectrochemical (PEC) water oxidation upon visible-light irradiation (>420 nm). Without the assistance of additional sacrificial agents or co-catalysts, a good photocurrent response of 4.1 μA cm−2 at +0.6 V (vs. Ag/AgCl) was achieved through facile molecular modulation of the polymer, which improved the uniformity and crystallinity of the film and facilitated charge transport among polymer chains. Moreover, C12 was used for preparation of a composite film with TiO2 nanorod arrays via spin-coating to yield an approximately 11-fold higher anodic PEC activity than that of pure TiO2. Our results demonstrated the great potential of solution-processable conjugated polymers for facile construction of highly efficient PEC devices for water splitting. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore)

As a demonstration of an alternative to the challenges faced with batch pharmaceutical manufacturing including the large production footprint and lengthy time-scale, we previously reported a refrigerator-sized continuous flow system for the on-demand production of essential medicines. Building on this technology, herein we report a second-generation, reconfigurable and 25 % smaller (by volume) continuous flow pharmaceutical manufacturing platform featuring advances in reaction and purification equipment. Consisting of two compact [0.7 (L)×0.5 (D)×1.3 m (H)] stand-alone units for synthesis and purification/formulation processes, the capabilities of this automated system are demonstrated with the synthesis of nicardipine hydrochloride and the production of concentrated liquid doses of ciprofloxacin hydrochloride, neostigmine methylsulfate and rufinamide that meet US Pharmacopeia standards.

A novel conjugated polymer (PDBDBM) was developed by the polymerization of 1,4-dioctyloxy-2,5-diethynylbenzene with 1,3-bis(4-bromophenyl)propane-1,3-dione based on Pd-catalyzed Sonogashira-coupling reaction. The obtained polymer PDBDBM exhibited bright green photoluminescence under UV irradiation. According to the metal ion titration experiments, PDBDBM showed high sensitivity and selectivity for detection of Cu2+ and Fe3+ over other metal ions. The fluorescent detection limits of PDBDBM were calculated to be 5 nM for Cu2+ and 0.4 μM for Fe3+ and the Stern–Volmer quenching constant for Cu2+ and Fe3+ were found to be 1.28 × 108 M−1 and 2.40 × 104 M−1, respectively. These results indicated that the polymer can be used as a potential probe for Cu2+ and Fe3+ detection.

For power machine pipeline, a pipeline isolator with integrated pipeline surrounding rubber and base vibration isolating rubber is designed. Adjusting the rubber parameters of the pipeline mainly changes the impedance of the isolator and adjusting the base rubber mainly changes the force transfer rate. Thus the optimal vibration isolation effect can be achieved by increasing the rubber hardness of the pipe surrouding rubber and reducing the rubber hardness of the base rubber. The analysis also shows that the base rubber structure has a decisive influence on the low-frequency vibration isolation performance of the integrated pipeline isolator compared to the pipeline rubber.