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Efficient blue-light-excitable broadband cyan-emitting phosphors may yield full-visible-spectrum white light-emitting diodes (WLEDs) with ultrahigh color rendering (Ra > 95). However, this requires closing the “cyan gap” in the 480–520 nm region of the visible spectrum, which is challenging. Herein, a well-performed cyan-emitting garnet phosphor Ca2LuAlGa2Si2O12:Ce3+(CLAGSO:Ce3+) is reported. Under 430 nm excitation, the optimal CLAGSO:5%Ce3+compound exhibits a broadband cyan emission (peak, 496 nm; bandwidth, 102 nm) with a high internal quantum efficiency of 85.6% and an excellent thermal resistance performance (69.1% at 423 K). Importantly, this as-prepared cyan-emitting phosphor provides sufficient cyan emission and enables filling the well-known so-called “cyan gap” between the blue LED chip and the commercial Y3Al5O12:Ce3+(YAG:Ce3+) yellow phosphor. Impressively, a WLED device fabricated with the optimal CLAGSO:5%Ce3+sample shows a low correlated color temperature (4053 K) and an ultrahigh color rendering index (Ra = 96.6), as well as an excellent luminous efficacy (74.09 lm W–1). These results highlight the importance of blue-excited broadband cyan-emitting phosphors in closing the cyan gap and enabling human-centric full-visible-spectrum warm WLED devices for high-quality solid-state lighting.

Phosphate compounds with outstanding chemical and physical satbility are attractive materials for the development of inorganic phosphors toward phosphor-converted white light-emitting diodes (pc-WLEDs). Herein, we demonstrate efficient, high-color-purity, red-emitting Ca8MEu(PO4)7(M = Mg and Zn) phosphate-type phosphors for near-ultraviolet (near-UV)-pumped pc-WLEDs. These samples were synthesized by using a high-temperature solid-state reaction method, and X-ray diffraction (XRD), XRD Rietveld refinements, scanning electron microscopy (SEM), SEM mapping, energy-dispersive X-ray spectroscopy (EDS), diffuse reflection spectra, photoluminescence excitation and emission, luminescence lifetimes, CIE chromaticity coordinates, temperature-dependent emission spectra were used to characterize them. The Rietveld refinement results demonstrate that the as-prepared phosphor samples crystallize in the hexagonal system, space group of R3cwith lattice parameters of a = 10.35813 Å, b = 10.35813 Å, c = 37.10859 Å, V = 3448.002(0.310) Å3for Ca8MgEu(PO4)7while a = 10.36894 Å, b = 10.36894 Å, c = 37.13377 Å, V = 3457.551(0.102) Å3for Ca8ZnEu(PO4)7. Upon near-UV excitation at 395 nm, Ca8MEu(PO4)7phosphors produce bright characteristic red emissions of Eu3+ions in the 550–750 nm wavelength range with peaks around 593, 620, 655 and 702 nm corresponding to 5D0→7FJ(J = 1, 2, 3, 4) transitions. Impressively, the CIE color coordinates of Ca8MEu(PO4)7are calculated to be (0.6699, 0.3298) for M = Mg and (0.6680, 0.3318) for M = Zn, which are very close to ideal red light (0.6700, 0.3300), and thus ultrahigh color purity values are obtained (94.4 % for M = Mg; 92.3 % for M = Zn). Moreover, the emission intensity and CIE color coordinates of Ca8MEu(PO4)7phosphors are better compared with commercial Y2O3:Eu3+red phosphor. Furthermore, the Ca8MEu(PO4)7red phosphors also exhibit good thermal stability at high temperature. Finally, the fabricated WLED device demonstrates a bright white-light emission with CIE color coordinates of (0.3637, 0.3751), high color rendering index of 80.7, low correlated color temperature of 4473 K and luminous efficiency of 20.40 lm W−1when upon a 80 mA driving current.

AbstractGreen growth is deliberated as an effective way for attaining environmental sustainability, but the nexus between fiscal spending and green growth is ignored in highly polluted Asian economies. To fill this gap, this study attempts to investigate the impact of public sector education and research and development expenditures on green economic growth for selected Asian economies for the period 1991–2019. The study employed FMOLS and DOLS methods to assess the association between public expenditures on education and research and development sectors and green economic growth. The study found that education and research and development expenditures both contribute significantly to enhancing green economic growth in most of the selected Asian economies. The study proposed some important policy implications for fostering green economic growth and environmental sustainability by mitigation of pollution emissions.

Antibiotic treatment failure against life-threatening bacterial pathogens is typically caused by the rapid emergence and dissemination of antibiotic resistance. The current lack of antibiotic discovery and development urgently calls for new strategies to combat multidrug-resistant (MDR) bacteria, especially those that survive in host cells. Functional nanoparticles are promising intracellular drug delivery systems whose advantages include their high biocompatibility and tunable surface modifications. Inspired by the fact that the rigidity of nanoparticles potentiates their cellular uptake, rigidity-functionalized nanoparticles (RFNs) coated with bacteria-responsive phospholipids were fabricated to boost endocytosis, resulting in the increased accumulation of intracellular antibiotics. Precise delivery and high antibacterial efficacy were demonstrated by the clearing of 99% of MDR bacteria in 4 h using methicillin-resistant Staphylococcus aureus(MRSA) and pathogenic Bacillus cereusas models. In addition, the subcellular distribution of the RFNs was modulated by altering the phospholipid composition on the surface, thereby adjusting the electrostatic effects and reprograming the intracellular behavior of the RFNs by causing them to accurately target lysosomes. Finally, the RFNs showed high efficacy against MRSA-associated infections in animal models of wound healing and bacteremia. These findings provide a controllable rigidity-regulated delivery platform with responsive properties for precisely reprograming the accumulation of cytosolic antibiotics, shedding light on precision antimicrobial therapeutics against intracellular bacterial pathogens in the future.

Phosphor-containing white light-emitting diodes (LEDs) with low color-correlated temperatures (CCTs) and high color rendering indexes (CRIs) are highly desirable for energy-efficient and environmentally friendly solid-state light sources. Here, we report a new and efficient blue light-excited, green-emitting Ce3+-activated CaY2ZrScAl3O12phosphor, which underpins the fabrication of high-color quality and full-visible-spectrum warm-white LED devices with ultrahigh CRI values (Ra > 96 and R9 > 96). A family of CaY2ZrScAl3O12:Ce3+phosphors with different Ce3+dopant concentrations were prepared by high-temperature solid-state synthesis. X-ray diffraction and corresponding Rietveld refinement reveal a garnet structure with an Ia3̅dspace group and crystallographic parameters a= b= c= 12.39645(8) Å, α = β = γ = 90°, and V= 1904.99(4) Å3. Luminescence properties were studied in detail as a function of Ce3+with the optimal concentration 1% mol. Impressively, CaY2ZrScAl3O12:1%Ce3+exhibits a broad excitation band from 370 to 500 nm, peaking at ∼421 nm, which is well matched with emission from commercial blue LED chips. Under 421 nm excitation, the CaY2ZrScAl3O12:1%Ce3+phosphor produces dazzling green light in a wide emission band from 435 to 750 nm (emission peak: 514 nm; full width at half-maximum: 113 nm), with a high internal quantum efficiency of 63.1% and good resistance to thermal quenching (activation energy of 0.28 eV). A white LED device combining a 450 nm blue LED chip with CaY2ZrScAl3O12:1%Ce3+green phosphor and commercial CaAlSiN3:Eu2+red phosphor as color converters demonstrates bright warm-white light with excellent CIE color coordinates of (0.3938, 0.3819), low CCT of 3696 K, high CRI (Ra = 96.9, R9 = 98.2), and high luminous efficacy of 45.04 lm W–1under a 20 mA driving current. New green phosphors enable the design and implementation of efficient luminescent materials for healthy solid-state lighting.

High-color-rendering full-spectrum warm-white light-emitting diodes (LEDs) are in great demand in the field of high-end solid-state white lighting. However, the so-called cyan gap (480–520 nm) in conventional white LEDs always limits their color rendering index (CRI) values, and thus there is a pressing need for cyan phosphors to fabricate full-spectrum white LEDs. Herein, we report on an efficient violet-excited blue-cyan-emitting Ca2YHf2GaAl2O12:Ce3+(CYHGA:Ce3+) garnet phosphor, which is capable of realizing full-spectrum warm-white LEDs with superior CRI (Ra = 98.2, R12 = 96, R9 = 95) and low correlated color temperature (CCT) of 3735 K. Importantly, when excited at 398 nm, the optimal CYHGA:2%Ce3+sample exhibits a strong broadband blue-cyan emission (emission peak: 473 nm; emission bandwidth: 92 nm) with high luminescence efficiency (internal quantum efficiency: 69.9 %; external quantum efficiency: 43.3 %), which perfectly covers both blue and cyan spectral region and enables to close the so-called cyan gap. The fabricated warm-white LED device based on CYHGA:2%Ce3+blue-cyan phosphor generates bright warm-white lights with ultra-high CRI values (Ra ≥96.5; R12 ≥ 94; R9 ≥ 93) and low CCT values (3674–3845 K) upon 20–320 mA driving currents. Thus, blue-cyan-emitting CYHGA:Ce3+garnet phosphors possess a bright application prospect in high-quality full-spectrum LED lighting.

We, the Editors and Publisher of Economic Research-Ekonomska Istraživanja, have retracted the following article:Xiaoyong Huang, Guorong Li, Jiayu Zhang, Liheng Li & Xiangyun Xu, ‘Rise in house prices and industrial growth: evidence from city-level data of China’, Economic Research-Ekonomska Istraživanja, 2020, 10.1080/1331677X.2020.1804969This article has been retracted at the request of the authors due to a major error found post-publication in the definition of the variables within the data which could invalidate the conclusions.

Friction is a kind of inherent and nonlinear disturbance in feed systems, which inevitably deteriorates motion accuracy at velocity reversal. Position error caused by friction is integrally effected by three aspects of feed drives, including command, control, and mechanical subsystems. Unfortunately, the traditional analyses hardly consider all mentioned aspects. Especially, no research has been reported on control characteristic at reverse motion. The purpose of this paper is to reveal the generation mechanism of friction error of a feed drive based on the commercial computer numerical control with three-loop control structure and velocity feedforward and proportional–proportional–integral controllers. Firstly, the generation process of the friction error at velocity reversal is profoundly investigated. Based on it, a simplified control model is conducted to explain transition from presliding to sliding regimes. It is the bond of analyzing friction error from command, control, and mechanical subsystems. Subsequently, the processes of presliding, acceleration, and adjustment stages are analyzed. Moreover, analytical formulas are derived to predict the durations of three stages and describe the shape of friction error. Then, the contour errors of linear and circular motion caused by friction can be predicted online. Experiments are introduced to verify the effectiveness of the proposed methods and formulations.

ABSTRACTHere, we investigated the effects and molecular mechanisms of metabotropic glutamate receptor 6 (mGluR6) on rat embryonic neural stem cells (NSCs). Overexpression of mGluR6 significantly promoted the proliferation of NSCs and increased the diameter of neutrospheres after treatment for 24 h, 48 h and 72 h. Overexpression of mGluR6 promoted G1 to S phase transition, with significantly decreased cell ratio in G1/G0 phase but significantly increased cell ratio in S phase. Additionally, mGluR6 overexpression for 48 h decreased the early and late apoptosis significantly. Moreover, overexpression of mGluR6 significantly increased the expression of p-ERK1/2, Cyclin D1 and CDK2, while the expression of p-p38 was significantly decreased. On the contrary, these effects of mGluR6 overexpression were reversed by mGluR6 knockdown. In conclusion, mGluR6 promotes the proliferation of NSCs by activation of ERK1/2-Cyclin D1/CDK2 signaling pathway and inhibits the apoptosis of NSCs by blockage of the p38 MAPK signaling pathway.

Graphical abstract Highlights • Internal electric field induced photocatalytic properties. • Improved photo generated electron hole separation. • Piezo, Pyro and Ferroelectric semiconductor for photocatalyst. Abstract Photocatalysis denotes as an environmental friendly chemical transformation technique. The rate of photoinduced electron–hole recombination is one of the difficulties encountered in semiconductor photocatalysis. Different alternative systems were suggested to overcome this problem and thereby improve the efficiency of the photocatalyst. Extensively investigated methods were not effective to achieve the required efficiency of the catalyst, because the catalyst charge carrier separation is poor. Among the explored methods, the electron–hole separation using built-in electric field attracts considerable attention as a new concept. A spontaneous potential from the ferroelectric material strongly minimizes the number of photoinduced electron–hole recombination. On the other hand, the spontaneous potential was compensated by the external and internal charge and to alternate the electric field, thermal, mechanical and electric field were applied as an external force. The external force was exerted by different methods, including passage of ultrasound waves, fluid eddy, flowing water, mechanical distribution and changing the temperature. Preliminary work has been carried out using semiconductor-Ferroelectric nanohybrid piezophotocatalyst in environmental remediation for the removal of an organic color and non-colored pollutants. Later, the application was extended to hydrogen production from water splitting and antibacterial material development. Furthermore, the light free catalysts such as piezocatalyst, dark catalyst and vibration catalyst are also examined for last decades. In this review, we summarize the work carried out by the internal electric field induced photocatalyst electron–hole separation (Piezo photocatalyst) and temperature triggered catalyst (Pyrocatalyst). Light free or vibration catalyst (piezocatalyst) work also briefly covered in this review. Overall, the manuscript was discussed in four categories of materials, including BaTiO 3 , ZnO, other ABO3 structures and two-dimensional nanostructures including MoS 2 , WS 2 , MoSe 2. The challenges encountered, and the present and future scope of the work is also discussed in this review. [ABSTRACT FROM AUTHOR]

This article investigates the control of attitude stabilization for a rigid spacecraft using non-singular terminal sliding mode control (NTSMC). A new problem with the traditional NTSMC has been pointed out. This issue is that the mathematical expression of the upper bound of convergence time will approach infinity as the angular velocity approaches zero. In order to address this issue in the traditional NTSMC, a new control method is proposed. This method utilizes the technique of “adding a power integrator” (AAPI), and provides a bounded expression for convergence time. When considering external disturbances, control input limitations, and actuator faults, the attitude and angular velocity can eventually stabilize to a residual set of equilibrium within a finite time. The simulation results demonstrate that the proposed controllers achieve highly accurate and resilient attitude control performance.

Phosphor-converted white-light-emitting diodes (WLEDs) with superhigh color rendering index (CRI) are the ongoing pursuit of next-generation solid-state lighting. One of the most important challenges is the limited improvement in CRI on account of the absence of a cyan component in the typical commercial combination. Here, a bright broad-band cyan-green-emitting phosphor with cubic garnet structure, SrLu2Al3ScSiO12:Ce3+(SLASSO:Ce3+), was successfully reported, which can compensate for the absence of cyan cavity in the 480–520 nm blue-green emission region. With 439 nm blue-light irradiation, the as-fabricated SLASSO:Ce3+phosphor yields a broad-band cyan-green emission with the maximum emission peak positioned at 525 nm and an appropriate full width at half-maximum (fwhm) of 111 nm, capable of providing more cyan emission component without sacrificing green emission. Meanwhile, the optimal SLASSO:2%Ce3+phosphor features CIE color coordinates of (0.3254, 0.5470) with cyan-green hue, along with a high internal quantum efficiency of up to 93%. Additionally, thermal stability measurements at different temperatures reveal that the luminescence emission intensity of the proposed phosphor retains 44% of its original integral emission intensity at 423 K with respect to room temperature, while also demonstrating an excellent color stability (ΔE= 5.4 × 10–3). This work shows that the highly efficient SLASSO:Ce3+garnet phosphor can be utilized as a potential cyan-green-emitting phosphor for filling the cyan gap, resulting in the construction of a high-quality warm WLED with high CRI for “human-centric” sunlight-like full-spectrum solid-state illumination.

Many primary-tumor subregions have low levels of molecular oxygen, termed hypoxia. Hypoxic tumors are at elevated risk for local failure and distant metastasis, but the molecular hallmarks of tumor hypoxia remain poorly defined. To fill this gap, we quantified hypoxia in 8,006 tumors across 19 tumor types. In ten tumor types, hypoxia was associated with elevated genomic instability. In all 19 tumor types, hypoxic tumors exhibited characteristic driver-mutation signatures. We observed widespread hypoxia-associated dysregulation of microRNAs (miRNAs) across cancers and functionally validated miR-133a-3p as a hypoxia-modulated miRNA. In localized prostate cancer, hypoxia was associated with elevated rates of chromothripsis, allelic loss of PTENand shorter telomeres. These associations are particularly enriched in polyclonal tumors, representing a constellation of features resembling tumor nimbosus, an aggressive cellular phenotype. Overall, this work establishes that tumor hypoxia may drive aggressive molecular features across cancers and shape the clinical trajectory of individual tumors.

In this Letter, we report a novel NaLaMgWO_6:Mn^4+ double-perovskite phosphor. Under the excitation at 342 nm, this phosphor showed a high-efficiency far-red emission at approximately 700 nm with internal quantum efficiency of up to 60%. Moreover, it exhibited a high thermal stability; the emission intensity at 423 k was approximately 57% of that at room temperature. Finally, a prototype light-emitting diode (LED) device was fabricated using the combination of a NaLaMgWO_6:Mn^4+ far-red-emitting phosphor and 365-nm LED chip.

A 38-year-old right-handed woman presented to the hospital with subtle right facial palsy and global aphasia of 4 days’ duration. She found that she had aphasia when she suddenly woke up at midnight and reported a headache lasting for several hours. She had no fever, vomiting, seizures, or limb paralysis. She had had migraines with an occasional visual aura for > 10 years. She was not taking any medication and was a nondrinker and nonsmoker. She had no other significant medical background and family history.

In this work, we reported on high-brightness Eu^3+-activated Ca_3Lu(AlO)_3(BO_3)_4 (CLAB) red-emitting phosphors. Under 397 nm excitation, the CLAB:Eu^3+ phosphors showed intense red emissions at around 621 nm with CIE coordinates of (0.657, 0.343). The optimal doping concentration of Eu^3+ ions was found to be 30 mol. %, and the CLAB:0.3Eu^3+ sample possessed high-color purity of 93% and ultra-high internal quantum efficiency as great as 98.5%. Importantly, the CLAB:0.3Eu^3+ also had good thermal stability. Finally, a white-light-emitting diode (WLED) lamp with good color-rendering index was fabricated by using a 365 nm ultraviolet chip and the phosphor blends of CLAB:0.3Eu^3+ red-emitting phosphors, (Ba,Sr)_2SiO_4:Eu^2+ green-emitting phosphors, and BaMgAl_10O_7:Eu^2+ blue-emitting phosphors.

Friction is one of the disadvantages to obtain high speed and high accuracy in servo feed system. A new optimal method based on ant colony algorithm is proposed to overcome the problem of time-consuming and poor result when determining friction compensation pulse sequences parameters at reverse points in this paper. The intelligent process can be rapidly realized by evaluating fitness function, which is composed of peak and mean errors of quadrant friction errors. An improved version of roulette strategy is introduced to improve search efficiency and avoid encountering local optimization, called improved ant colony algorithm (IACO). In addition, because of its openness and universality, it is easily embedded in CNC System. The experimental result is presented to illustrate the effectiveness of this approach in suppressing mean and peak errors at the reverse point. It is shown that the improved method has advantages of strong convergence, remarkable effect and better robustness, which promotes contour accuracy around reverse points.

To study the problem of the optimal production decision of risk-neutral company and risk-averse farmer under the 'company + farmer' rental model, this paper is based on the traditional newsboy model from the perspective of supply chain coordination. By introducing a leasing model, the optimal production decision of supply chain is analysed in case of considering expected rents. For the case of considering the expected rent, the risk-averse farmer's production decision-making problem is discussed by introducing conditional value-at-risk (CVaR) and the conclusion is drawn that when facing the lower labour costs of agricultural products, the farmer can effectively avoid risks by using rental model under the 'company + peasant household'.

•A stent-assisted thrombectomy can use in symptomatic intracranial hemorrhage.•Contact aspiration plus stent retriever catheters have high chances of reperfusion.•Contact aspiration + stent retriever has fewer disease-related adverse effects.•The reperfusion parameter should be used to evaluate mechanical thrombectomy.•Failure attempts increased procedural time and procedural-adverse effects.

High-efficiency far-red emitting phosphors with emission peak around 730 nm are urgently needed for indoor plant growth light-emitting diode (LED) lighting. In this article, we report on the synthesis, crystal structure and luminescence properties of a new highly efficient Mn4+ion activated Li3La3W2O12(LLWO) far-red emitting phosphor. A group of LLWO:Mn4+phosphors doped with different Mn4+ion concentrations have been prepared via the conventional high-temperature solid-state reaction route. X-ray diffraction Rietveld refinement reveals that the LLWO:Mn4+phosphor has the monoclinic structure with space group P21/n, along with lattice parameters of a= 5.5396 Å, b= 5.6026 Å, c= 7.8802 Å, α= γ= 90°, β= 90.0988°, and V= 244.57 Å3. Interestingly, LLWO:Mn4+phosphors can generate bright narrowband far-red emission in the 650-800 nm wavelength range peaking at 719 nm due to the spin- and parity-forbidden 2Eg→4A2gtransition of Mn4+ions, matching well with the absorption spectrum of phytochrome PFR. The excitation spectrum monitored at 719 nm has a broad excitation band with the range from 250 to 550 nm centered at 339 nm and 472 nm, indicating that LLWO:Mn4+phosphors could be efficiently pumped by both ultraviolet and blue LED chips. The highest far-red emission is achieved for the sample doped with 1.2 mol% Mn4+ion, and this optimal LLWO:1.2%Mn4+sample shows a high internal quantum efficiency of 88.4% and a decay lifetime of 2.289 ms. CIE color coordinates of Li3La3W2O12:1.2%Mn4+are determined to be (0.7326, 0.2674). Besides, the crystal field analysis and temperature-dependent spectra of the as-prepared samples have been investigated in detail. The emission intensity of LLWO:1.2%Mn4+sample at 423 K remains about 40% of that at 303 K. Finally, a LED device is fabricated by integrating the LLWO:1.2%Mn4+phosphors and a 460 nm blue LED chip, which shows bright blue and far-red dual emission bands under 20-300 mA driving currents. This work demonstrates that these newly developed far-red emitting LLWO:Mn4+phosphors have excellent application prospects in plant growth LED lighting.

Online monitoring and source tracing of machining error is of great significance for ensuring machining quality and improving machining efficiency. For an open numerical controller, the built-in sensors signals can be captured through driver interface in machining process. These signals contain various information of machining conditions of machine tool. The capture and analysis of the built-in sensors signals can be used for the online monitoring and source tracing of machining error. In this paper, an novel approach is developed for machining error monitoring and source tracing based on built-in sensor signal analysis and multi-body system theory. A ball screw grinding process was monitored, and the analysis results show the validity of the approach.

To improve dynamic performance of servo feed system and aim at automatically calculating optimal controller parameters to increase contour accuracy and manufacturing efficiency. An improved particle swarm algorithm (IPSO) is adapted to optimize control parameters on line, and to match the control parameters of bi-axial servo feed system in this paper. Linearly decreasing acceleration weights is introduced to improve global searching ability in early stage and converge to global optimization at the end of the search. At the same time, adaptive maximum speed limit is introduced to control the scale of search and improve convergence efficiency. The experimental results demonstrate that the novel method is effective at reducing the follow error and contour error.

In this Letter, I present a versatile strategy to enhance the near-infrared to near-infrared (NIR-to-NIR) upconversion luminescence from sub-10-nm ultra-small LaF_3:Yb^3+/Tm^3+ colloidal nanoparticles through lanthanide doping under 980 nm laser excitation. It is interesting that the NIR-to-NIR upconversion emission at 801 nm of LaF_3:Yb^3+/Tm^3+ nanoparticles can be improved by increasing the Tm^3+ doping concentration or by introducing another lanthanide activator (Er^3+ or Ho^3+) as a sensitizer. The luminescence enhancement effect showed a strong dependence on the doping concentrations of activator ions (Tm^3+, Er^3+, or Ho^3+). Particularly, adding 1 mol. % Ho^3+ ions into LaF_3:Yb^3+/Tm^3+ nanoparticles induced a 2.85-fold enhancement in NIR 801 nm emission of Tm^3+ ions. The related upconversion emission mechanisms were investigated and discussed.

In this work, colloidal hexagonal-phase (NaYF_4:Nd^3+/Yb^3+/Ho^3+)/(NaYF_4:Nd^3+/Yb^3+) core/shell nanoparticles with intense visible upconversion emissions under 808-nm laser excitation were prepared. Compared with the core-only nanoparticles, a maximum 990-fold overall enhancement in the emission intensity of Ho^3+ ions was achieved with the help of active-shell coating design, due to the significant increase in the near-infrared absorption and efficient energy transfer from Nd^3+ primary-sensitizers to Ho^3+ activators via Yb^3+ bridging sensitizers. The luminescence-enhancement effect exhibited a strong dependence on the doping concentrations of NaYF_4:Nd^3+/Yb^3+ active-shell. The optimal concentrations of Nd^3+ and Yb^3+ ions in the active-shell layer were found to be 30 and 5 mol. %, respectively. Moreover, the upconversion emission intensity of NaYF_4:Nd^3+/Yb^3+-coated nanoparticles was about 2.5 times higher than the one coated with a NaYF_4:Nd^3+ active-shell.

A novel controller parameter optimisation method to effectively improve the motion accuracy of a servomechanism is proposed in this article. This method overcomes the drawbacks of conventional controller parameter optimisation methods, such as inefficiency and dependence on experience. The servomechanism model was established, and a performance analysis was performed. Moreover, the design requirements were developed. The robust stability was adopted to solve the problem induced by great variations in the modelling elements. Subsequently, a multi-objective nonlinear optimisation problem was developed and solved by an intelligent optimisation algorithm. To achieve the desired performance, the multi-objective optimisation function adopted a comprehensive command response performance function and an external disturbance rejection response function. To validate the effectiveness and feasibility of this method by simulation and experiment, an open servomechanism platform was established. The simulated and experimental results show that the tracking error, protrusion error and performance indicators are all reduced greatly under different working conditions. This method can effectively improve the motion accuracy and has the advantages of high efficiency, high practicality and high flexibility.