Tuning electronic structure ofδ-MnO_(2) by the alkali-ion(K,Na,Li)associated manganese vacancies for high-rate supercapacitors

Cation vacancies can bring numerous surprising characters due to its multifarious electron and orbit distribution.In this work,d-MnO_(2) with alkali-ion(K,Na,Li)associated manganese(Mn)vacancies is fabricated by a simple hydrothermal reaction,and the correlation between their electronic structure and pseudocapacitance are systematically investigated.FESEM/TEM images have shown that the morphology of MnO_(2) is obviously changed after the introducing of cation vacancies.The position of alkali-ion in MnO_(2) structure can be controlled by adjusting the ion concentration.XRD patterns and Raman spectra demonstrate that the alkali-ion is embedded in Mn vacancies at low concentration,while entered the interlayer of MnO_(2) at high concentration.The existence of Mn vacancies will resulting in the distortion of neighboring atoms,leading to the electronic delocalization,and thus enhancing the conductivity,pseudocapacitance and rate capability of MnO_(2).Accordingly,the specific capacitances of optimized 0.4 KMO,0.4 NaMO and 0.4 LiMO samples are enhanced about 1.9,1.6 and 1.6 times compared to pure MnO_(2).Meanwhile,the rate performance has also been improved about 76%,46%and 42%,respectively.Theoretical calculations further confirm that the Mn vacancies can generate additional occupancy states and cause an increase in carrier concentration,which will improve the conductivity and further boost the pseudocapacitance of MnO_(2).This result open up a promising approach to explore active and durable electrode materials.

Polymorphism identification of carotenoid binding protein gene transcription in the silkworm, <i>Bombyx mori</i>

Carotenoids play important and diverse roles in insects and their uptake and transport rely on carotenoid binding protein (CBP). The study excavated a cluster of CBP-like transcripts, including full CBP from all of the six yellow cocoon Bombyx strains investigated. Sequencing of 54 cDNA clones revealed 17 different types of transcripts which derived from alternative splicing of CBP gene locus. Five of the novel transcripts were similar with spatial and temporal distribution patterns to CBP, but their expression levels were relatively lower. The author disclosed two more novel alternative spliced transcripts with different transcription start sites from CBP in the 5’ UTRs as well as 11 SNP sites neighboring intron 1 after amplification and sequencing. qRT-PCR analysis gave evidence that relatively more mRNA was transcribed from A-type CBP gene than that from B-type in tissues like silk gland and midgut. Sequences of A- and B-type CBP genes were different in length of domains neighboring the 5’ UTR, thus their mRNA varied both in quantity and transcript types. The SNPs surrounding intron 1 can serve as stable markers to distinguish transcripts from the two isoforms, and they can be used for molecular marker assisted selection.

Self-monitored Nd-doped MoSe_(2) nanosheets with near-infrared luminescent sensing for photothermal therapy

The acquisition of real-time temperature monitoring during photothermal therapy is significant to prevent unnecessary damage to healthy tissues.However,owing to complexity and diverse factors in microenvironment of cells,there still remain considerable challenges in achieving noninvasive temperature measurement and manipulation in therapeutic process.Herein,biocompatible Nd-doped MoSe_(2) nanosheets have been developed on the premise of excellent photothermal effect,which manifest desirable photoluminescence and distinct temperature self-monitored capability in near-infrared Ⅰ and Ⅱ bio-windows.Based on thermally coupled energy levels of Nd ions,the real-time monitoring on temperature changes in intracellular environment can be realized which provide instant temperature feedbacks to avoid side effects from hyperthermia.Exclusive of detrimental elements such as F and Pb,the objective nanosheets manifest satisfactory biosafety and can induce effective tumor ablation under near-infrared irradiation with photothermal conversion efficiency up to 40.8%,providing an innovative vision for developing more precisely and safely photothermal approaches.

Correlating O-deficiency and luminescence property of Tb^(3+)þdoped SrO

Cubic rock salt can lower down or break the rare earth transition barrier through interstitial or vacancy defects owing to its great deformation and rotationflexibility.Here,we demonstrate that oxygen vacancies in SrO are induced by proper oxidization and atmosphere adjustment,resulting in defects with various depths and crystalfield distortion.The thermally assisted tunneling from defects to 5 D_(4) state and electronic population decrease on 5 D_(3) state of Tb^(3+)þare observed by the deformation of adjacent oxygen octahedral structure.Finally,the asprepared SrO:0.01 Tb^(3+)þphosphors,commercial BaMgAl10O17:Eu^(2+)þblue phosphor,and CaAlSiN3:Eu^(2+)þred phosphor are mixed and coated onto 280 nm deep-ultraviolet LED chip to assemble white light-emitting LED device.The LEDs show CCT of 3850 K,4136 K,and 4741 K,with color rendering index of 90.3,90.8,and 92.1,respectively.These insights will advance the fundamental knowledge of crystal engineering in cubic rock salt,and enable new ways to manipulate energy transfer and electronic transition via defects.

Lanthanide near-infrared emission and energy transfer in layered WS2/MoS2 heterostructure

Lanthanide ions have attracted great attention due to their distinct photonic properties.The optoelectronic properties and device performance are greatly affected by the interfacial coupling between the layered van der Waals heterostructure,fabricated with two or more transition metal dichalcogenide(TMD)layers.In this work,lanthanide-doped WS2/MoS2 layered heterostructures have been constructed through two synthesis steps.The doped thin films are highly textured nanosheets on wafers.Importantly,the as-prepared heterostructure exhibits efficient near-infrared emission in the range of the telecommunication window,owing to energy transfer between lanthanide ions in the two TMD layers.The use of the layered heterostructure allows the decrease of deleterious cross-relaxation due to homogeneous doping or concentration quenching.The energy transfer process was further elaborated in this work.The results suggest that lanthanide ions can effectively extend the emission band of TMD thin films and their heterostructures.The doped TMD heterostructure is highly favourable for constructing atomically thin near-infrared photonic devices.

Reversible enhanced upconversion luminescence by thermal and electric fields in lanthanide ions doped ferroelectric nanocomposites

Luminescence modification of lanthanide ions has attracted great attention due to its applications in sensing,colorful display, information transmission and anti-counterfeiting. Traditional methods of tuning fluorescence typically employ tuning compositions that are not conducive to the development of multi-environment detection and anti-counterfeiting. In this study, lanthanide ions doped ferroelectric nanocomposite was exploited with external stimuli. The upconversion luminescence modification was preformed via both the thermal and electric fields. The anti-thermal quenching phenomenon was observed in the prepared nanocomposite, which could effectively enhance the upconversion luminescence of lanthanide ions. Based on the electromechanical softness of the ferroelectric lattice, exceptional luminescence modification was realized through electric polarization. The luminescence modifications by thermal and electric fields exhibited excellent reversibility and non-volatility. These results provide unique insights into the development of integrated stimulus responsive smart devices, colorful display and advanced multi-mode sensing materials.

Luminescent and thermometric properties of dual emitting Eu^(2+)/Sm^(3+) co-doped Sr_(4)La(PO_(4))_(3)O phosphor based on energy transfer

Eu^(2+)/Sm^(3+)co-doped dual-emitting Sr_(4)La(PO_(4))_(3)O phosphors were synthesized through a convenient high temperature solid state reaction in reductive atmosphere.The structure,luminescence,energy transfer and temperature-dependent luminescence properties of Eu^(2+)/Sm^(3+)co-doped Sr_(4)La(PO_(4))_(3)O phosphors were researched and analyzed in detail.The blue emission of Eu^(2+)and the red emission of Sm^(3+)can work together as FIR signals.Based on the different response characteristics of these two ion emissions to temperature,Sr_(4)La(PO_(4))_(3)O:Eu^(2+)/Sm^(^(3+))phosphor achieves the relative sensitivity of0.48384%/K and a wide range of temperature measurements from room temperature to 573 K.The results reveal that the Sr_(4)La(PO_(4))_(3)O:Eu^(2+)/Sm^(3+)phosphor has application prospect in the field of high temperature optical thermometry.The energy transfer mechanism is proved to be the dipole-dipole interaction between Eu^(2+)and Sm^(3+)ions.

Sintering Behavior and Microwave Dielectric Properties of MgTiO_3 Ceramics Doped with B_2O_3 by Sol-Gel Method

The B2O3-doped MgTiO3 powders and ceramics have been prepared by sol-gel method using Mg（NO3）2-6H2O, Ti（C4H9O）4 and H3BO3 as the starting materials. The sintering behavior and microwave dielectric properties of ceramics prepared from powders with different particle sizes were investigated. The gels were calcined at 650, 700, 750, 800, 850 and 900 ℃ and the derived particle sizes of powders were 20-30 nm, 30-40 nm, 40-60 nm, 60-90 nm, 90-120 nm and 120-150 nm, respectively. The nanoparticles with the size of 30-60 nm benefited the sintering process with high surface energy whereas nanoparticles with the size of 20-30 nm damaged the microwave dielectric properties due to the pores in the ceramics. The addition of B203 used as a liquid sintering aid reduced the sintering temperature of MgTiO3 ceramic, which was supposed to enter the MgTi03 lattice and resulted in the formation of （MgTi）2（BO3）O phase. The B203-doped MgTiO3 ceramic sintered at 1100℃ and prepared from the nanoparticles of 40-60 nm had compact structure and exhibited good microwave dielectric properties： εr=17.63, Q x f=33,768 GHz and Tf=-48X 10-6 ℃-1.

Thermal and luminescent properties of 2 μm emission in thulium-sensitized holmium-doped silicate-germanate glass

In this paper, we present the luminescent properties of Tm^(3+)∕Ho^(3+)co-doped new glass. A series of silicategermanate glass was prepared by the conventional melt-quenching method. In the Tm^(3+)∕Ho^(3+)co-doped silicategermanate glass, a strong emission of 2 μm originating from the Ho^(3+):~5I_7→~5I_8transition can be observed under conventional 808 nm pumping. The characteristic temperatures, structure, and absorption spectra have been measured. The radiative properties of Ho^(3+)in the prepared glass were calculated. The emission cross section of Ho^(3+)ions transition can reach 4.78 × 10^(-21)cm^2 around 2 μm, and the FWHM is as high as 153 nm. The energy transfer efficiency between Ho^(3+)and Tm^(3+)has a large value(52%), which indicates the Tm^(3+)∕Ho^(3+)co-doped silicategermanate glass is a suitable candidate for the 2 μm laser. Moreover, the energy transfer mechanism between Tm^(3+)and Ho^(3+)ions was investigated.

SrAl_(2)O_(4) crystallite embedded inorganic medium with super-long persistent luminescence,thermoluminescence, and photostimulable luminescence for smart optical information storage

As a leader of long persistent luminescence(LPL) materials, the optical properties of aluminate phosphor have remained unsurpassed for many years. As a powder material, its practical application will always be limited to the field of security signs. In this paper, the SrAl_(2)O_(4)∶Eu^(2+), Dy^(3+)inorganic solid material with comparable LPL properties to powder materials was obtained. The crystallization mechanism and crystallite micro-morphology of inorganic glass materials have been studied, and a new opinion is put forward that the large-size SrAl_(2)O_(4)crystallites in the glass matrix are stacked by rod-shaped crystals arranged in a regular direction. In addition,the SrAl_(2)O_(4)∶Eu^(2+), Dy^(3+)glass obtained cannot only collect high-energy photons but also is sensitive to lowenergy sunlight. The results show that the material exhibits superior performance in LPL, thermoluminescence,and photostimulable luminescence. Based on this property, a new application of this material in the field of information storage was explored. This paper has a certain reference value for the development and application of aluminate LPL materials in the field of smart optical information storage.

Emission tunable of Mg_(0.695)Si_(0.695)Al_(1.39)O_(3.65)N_(0.35):Eu^(2+),Mn^(2+) oxynitride phosphors via energy transfer for WLEDs

A series of Eu^(2+)doped and Eu^(2+)/Mn^(2+) co-doped Mg_(0.695)Si_(0.695)Al_(1.39)O_(3.65)N_(0.35)(MSAON) phosphors were synthesized by solid-state reaction at a lower temperature of 1500℃.The crystal morphology and structure of MSAON host were characterized by SEM,TEM and XRD.The quantum yield(QY) for Eu^(2+)doped MSAON phosphors was measured as high as 62%,indicating the excellent luminous efficiency.For the Eu^(2+)/Mn^(2+)co-doped MSAON phosphor,the photoluminescence spectrum and delay curves reveal the efficient energy transfer(ET) process from Eu^(2+)to Mn^(2+)ions.Meanwhile,the corresponding energy transfer efficiency,critical distance and mechanism are discussed in detail.Temperature-dependent emission spectrum shows the thermal and color stabilities.The emission color of MSAON:Eu^(2+),Mn^(2+)phosphors could be tuned from blue through white to red via varying the concentration of Mn^(2+) ions.White-light-emitting diodes(WLEDs) were successfully fabricated by encapsulating the phosphors in nUV LED(365 nm) devices obtaining white light with color rendering index(CRI) as high as 87.7.The results reveal that the MSAON:Eu^(2+),Mn^(2+)phosphors could have potential application in the field of n-UV WLEDs.

An optical thermometer with high sensitivity and superior signal discriminability based on dual-emitting Ce^(3+)/Eu^(2+)co-doped La5Si2BO13 thermochromic phosphor

A novel non-contact optical thermometer,qualified with high sensitivity and temperature resolution,is urgently needed for temperature measuring of micro devices,moving objects and specific severe environments.Hence,a series of dual-emitting La_(5)Si_(2)BO_(13):Ce^(3+),Eu^(2+)phosphors were synthesized.The two ions show diverse responses with the changing in temperature.The variational emissions of Ce^(3+)and Eu^(2+)can be converted to FIR(fluorescence intensity ratio)signals.The maximal absolute sensitivity Sa and relative sensitivity Sr reach up to 0.07526%/K and 3.2241%/K,respectively.It is worthy noting that the Sa and Sr possess the same variation tendency and both have high values in the low temperature region(293-373 K),showing the great temperature measuring property especially in low temperature region.The temperature sensing characteristics are superior to the results of most previous reports.The energy transfer(ET)process is certified to occur from Ce^(3+)to Eu^(2+)ions.These studies indicate that La_(5)Si_(2)BO_(13):Ce^(3+),Eu^(2+)phosphor could have a good prospect for optical thermometry.

Energy transfer and 2 μm emission in Tm^(3+)/Ho^(3+) co-doped(Y_(0.87)La_(0.1)Zr_(0.03))_2O_3 nanopowders

（Y0.87La0.1Zr0.03）2O3 nanopowders doped with various concentrations of Tm^3＋ and Ho^3＋ were prepared by the citrate method. The standard cubic Y2O3 phase can be matched in the Tm^3＋/Ho^3＋ co-doped（Y0.87La0.1Zr0.03）2 O3 nanopowders. The nanopowders exhibit average particle sizes of 40,60, 80 and 100 nm after calcinated at 900,1000,1100 and 1200℃,respectively. The energy transfer from Tm^3＋ to Ho^3＋ and the optimum fluorescence emission around 2 μm were investigated. Results indicate that the emission bands at around 1.86 and 1.95 μm correspond to 3 F4→3 H6 transition of Tm^3＋ and 5 I7→5 I8 transition of Ho^3＋, respectively.Better spectral properties were achieved in Tm^3＋/Ho^3＋ co-doped（Y0.87La0.1Zr0.03）2O3 nanopowders with the average size of 100 nm obtained at the conditions of the treatment of precursors calcinated at 1200 ℃ for 2 h doped with 1.5 mol% Tm^3＋ and 1 mol% Ho^3＋.

Effect of Li＋ ion concentration on upconversion emission and temperature sensing behavior of La2O3：Er3＋ phosphors

The effects of Li~＋ co-doping concentration on the structure, upconversion luminescence and temperature sensing behavior of Er^（3＋）：La_2O_3 phosphors were investigated. X-ray diffraction and scanning electron microscopy observations reveal that Li~＋ ion co-doping can change the lattice parameter of La_2O_3 host and increase the particle size of the samples. The optical investigation shows that co-doping of Li~＋ ions can enhance the upconversion emission of Er^（3＋） ions in La_2O_3 matrix effectively. Most importantly, the temperature sensing sensitivity of the samples is found to be dependent on Li~＋ co-doping concentration,when the emission intensity ratio of the（~2H_（11/2）→~4 I_（15/2）） and（~4 S_（3/2）→~4 I_（15/2）） transitions of Er^（3＋） is chosen as the thermometric index. Both of the optimum upconversion luminescence and temperature sensing sensitivity are obtained for 7 mol% Li~＋ co-doped sample. When the Li~＋ concentration is beyond 7 mol%,both the quenching in upconversion intensity and the degradation of temperature sensitivity are observed, which may be due to the serious distortion in local crystal field around Er^（3＋） ions caused by the excess Li~＋ ions.

Next generation lanthanide doped nanoscintillators and photon converters

Scintillators are of significance for the realization of indirect X-ray detection and X-ray excited optical luminescence(XEOL)imaging.However,commercial bulk scintillators not only require complex fabrication procedures,but also exhibit non-tunable XEOL wavelength and poor device processability.Moreover,thick crystals usually generate light scattering followed by evident signal crosstalk in a photodiode array.Lanthanide doped fluoride nanoscintillators(NSs)prepared with low-temperature wet-chemical method possess several advantages,such as low toxicity,cheap fabrication cost,convenient device processability and adjustable emission wavelengths from ultraviolet to visible and extending to second near infrared window.In addition,they exhibit X-ray excited long persistent luminescence(XEPL)making them suitable for broadening the scope of their applications.This review discusses and summarizes the XEOL and XEPL characteristics of lanthanide doped fluoride NSs.We discuss design strategies and nanostructures that allow manipulation of excitation dynamics in a core-shell geometry to simultaneously produce XEOL,XEPL,as well as photon upconversion and downshifting,enabling emission at multiple wavelengths with a varying time scale profile.The review ends with a discussion of the existing challenges for advancing this field,and presents our subjective insight into areas of further multidisciplinary opportunities.

Light-driven soft actuator based on graphene and WSe2 nanosheets composite for multimodal motion and remote manipulation

Remote controlled soft actuators have attracted ever-increasing interest in industrial,medical,robotics,and engineering fields.Soft actuators are charming than normal tools in executing dedicate tasks due to small volume and flexible body they have.However,it remains a challenge to design soft actuator that can adapt to multi-environments under remote stimuli with promising nano materials.Herein,we have developed a kind of near-infrared laser driven soft actuators with multi locomotive modes based on WSe2 and graphene nanosheets heterojunction.Different locomotion modes are driven by photothermal effect induced deformation to adapt to different working conditions.Moreover,the specially designed gripper driven by pulsed laser can lift a heavy load which is four times of its weight.This work broadens the choice of advanced nanomaterials for photothermal conversion of soft actuators.It is promising to realize applications including photothermal therapy and complex environment detection through the combination of the intelligent robot design and optical fiber system.

Enhancing light yield of Tb^(3+)-doped fluoride nanoscintillator with restricted positive hysteresis for low-dose high-resolution X-ray imaging

Developing scintillators with high light yield(LY),superior irradiation stability,and weak afterglow is of significance for the realization of low-dose high-resolution X-ray excited optical luminescence(XEOL)imaging.Lanthanide doped fluoride nanoparticles possess low toxicity,superior environmental stability,facial fabrication process,and tunable emissions,which are appropriate candidates for the next generation nanoscintillators(NSs).However,the low LY and strong positive hysteresis greatly restrict their practical application.Here,we propose an effective strategy that engineers energy gap to significantly enhance the LY.Our results verify that the tetragonal LiLuF4 host benefits the crystal level splitting of Tb^(3+)ions,which greatly promotes the electrons population on the Tb^(3+):5D4 level followed by the enhanced LY.The LY of LiLuF4:Tb@LiLuF4 NSs is calculated to be~31,169 photons/MeV,which is much higher than the lead halide perovskite colloidal CsPbBr3(~21,000 photons/MeV)and LuAG:Ce(~22,000 photons/MeV)scintillators.Moreover,the positive hysteresis is remarkably restricted after coating a thin shell.The X-ray detection limit and spatial resolution are measured to be~21.27 nGy/s and~7.2 lp/mm,respectively.We further verify that this core/shell NS can be employed as scintillating screen to realize XEOL imaging under the low dose rate of 13.86μGy/s.Our results provide an effective route to develop high performance NSs,which will promote great opportunities for the development of low-dose high-resolution XEOL imaging devices.

Sunlight activated ultra-stable long persistent luminescence glass ceramic for outdoor information display

Natural sunlight activated persistent luminescence(PeL)is ideal candidate for optical information display in outdoors without the requirement of electric supply.Except the brightness and duration,the stability especially water resistance of the PeL materials is of significant importance for practical application,which remains a great obstacle up to date.Herein,we report a new sunlight activated PeL glass ceramic containing hexagonal Sr_(13)Al_(22)Si_(10)O_(66):Eu^(2+)crystals,which exhibits strong blue PeL and can last more than 200 h.The PeL can be charged by the full wavelengths located in AM 1.5G due to the broad distribution of traps in the crystal structure.The PeL is clearly observed by the naked eye even after 24 h upon sunlight irradiation irrespective of the weather,and the photoluminescence intensity only decreased~3.3%after storing in water for 365 d.We demonstrate its potential application for thermal and stress responsive display as well as long-term continuous security indication upon sunlight irradiation,which not only save vast energy and reduce environment pollution,but also are appropriate for outdoor usage.

Empowering perovskite PbTiO_(3) nanoparticles with enhanced up-conversion luminescence and thermal sensitivity by introducing Er^(3+) dopant

Up-convertion(UC)perovskite Er^(3+)-doped Pb TiO3(Er-PTO)nanoparticles with green and red emissions were synthesized via the hydrothermal method.The UC properties were manipulated by adjusting the concentration of Er^(3+) ions dopant.The green emission intensity was decreased as the doping concentration increased from 1% to 4%(mole fraction),whereas the red emission intensity was increased.The influences of Er^(3+) ions on the temperature-sensing performance were further investigated.The results demonstrated that Er-PTO nanoparticles with doping 1% Er^(3+) ions possessed a sensitivity of3.1×10^(-3) K^(-1) at 475 K,presenting a high potential in optical heating devices.

Novel ultra-wideband fluorescence material:Defect state control based on nickel-doped semiconductor QDs embedded in inorganic glasses

In recent years,the development of an environmentally friendly quantum dots(QDs)embedded luminous solid by a simple method has attracted considerable attention.In this study,semiconductor ZnS QDs were successfully prepared in an inorganic matrix of amorphous glass,which yielded beneficial broadband emission in the long-wavelength region of the visible range.The strong red emission belonged to the defect state energy level of the ZnS QDs,which could be enhanced by incorporation of nickel ions into the fixed matrix to regulate the defects state.The novel material had a small self-absorption,wide excitation and emission ranges,and thus potential applications in light-conversion devices,luminescent solar concentrators,and solar cell cover glasses.