BACKGROUND Photoaging,a result of chronic sun exposure,leads to skin damage and pigmentation changes.Traditional treatments may have limitations in high-altitude areas like Yunnan Province.Intradermal Col Ⅰ injection...BACKGROUND Photoaging,a result of chronic sun exposure,leads to skin damage and pigmentation changes.Traditional treatments may have limitations in high-altitude areas like Yunnan Province.Intradermal Col Ⅰ injections stimulate collagen production,potentially improving skin quality.This study aims to assess the efficacy and safety of this treatment for photoaging.AIM To evaluate the efficacy and safety of intradermal typeΙcollagen(ColΙ)injection for treating photoaging.METHODS This prospective,self-controlled study investigated the impact of intradermal injections of ColΙon skin photodamage in 20 patients from the Yunnan Province.Total six treatment sessions were conducted every 4 wk±3 d.Before and after each treatment,facial skin characteristics were quantified using a VISIA skin detector.Skin thickness data were assessed using the ultrasound probes of the Dermalab skin detector.The Face-Q scale was used for subjective evaluation of the treatment effect by the patients.RESULTS The skin thickness of the right cheek consistently increased after each treatment session compared with baseline.The skin thickness of the left cheek significantly increased after the third through sixth treatment sessions compared with baseline.The skin thickness of the right zygomatic region increased after the second to sixth treatment sessions,whereas that of the left zygomatic region showed a significant increase after the fourth through sixth treatment sessions.The skin thickness of both temporal regions significantly increased after the fifth and sixth treatment sessions compared with baseline(P<0.05).These findings were also supported by skin ultrasound images.The feature count for the red areas and wrinkle feature count decreased following the treatment(P<0.05).VISIA assessments also revealed a decrease in the red areas after treatment.The Face-QSatisfaction with Facial Appearance Overall and Face-Q-Satisfaction with Skin scores significantly increased after each treatment session.The overall appearance of the patients improved after treatment.CONCLUSION Intradermal ColΙinjection improves photoaging,with higher patient satisfaction and fewer adverse reactions,and could be an effective treatment method for populations residing in high-altitude areas.展开更多
In the diagnosis and treatment of plastic surgery,there are structural processing problems,such as positioning,moving,and reconstructing complex threedimensional structures.Doctors operate according to their own exper...In the diagnosis and treatment of plastic surgery,there are structural processing problems,such as positioning,moving,and reconstructing complex threedimensional structures.Doctors operate according to their own experience,and the inability to accurately locate these structures is an important problem in plastic surgery.Emerging digital technologies such as virtual reality,augmented reality,and three-dimensional printing are widely used in the medical field,particularly in plastic surgery.This article reviews the development of these three technical concepts,introduces the technical elements and specific applications required in plastic surgery,summarizes the application status of the three technologies in plastic surgery,and summarizes prospects for future development.展开更多
Background: Coronary artery disease (CAD) is frequently observed in aging end-stage liver disease (ESLD) patients who require orthotopic liver transplantation (OLT). This situation is challenging for both the pa- tien...Background: Coronary artery disease (CAD) is frequently observed in aging end-stage liver disease (ESLD) patients who require orthotopic liver transplantation (OLT). This situation is challenging for both the pa- tients and the medical staff. Methods: We retrospectively studied the case records of 26 ESLD patients with CAD who underwent OLT with total clamping of the inferior vena cava between 2014 and 2018. We analyzed the details of the pre-operative evaluation, intraoperative anesthetic management and post-operative prognosis of these patients. Results: All patients tolerated the anhepatic stage well. Post-reperfusion syndrome (PRS) was observed in 13 patients (50%) and 2 of them were severe but corrected well. ST-segment depression was frequently observed during the anhepatic stage and reperfusion stage. No mortality due to cardiac-related events occurred among the patients during hospitalization. OLT with the modi ed piggyback technique could successfully be performed in ESLD patients with mild and moderate CAD. Conclusions: A thorough evaluation and optimization of recipients, strict monitoring and optimized man-agement of circulation, knowledge of the complicated changes during OLT procedures, and strategies to ameliorate post-reperfusion syndrome favorite the outcomes.展开更多
The COVID-19 has brought us unprecedented difficulties and thousands of companies have closed down.The general public has responded to call of the government to stay at home.Offline retail stores have been severely af...The COVID-19 has brought us unprecedented difficulties and thousands of companies have closed down.The general public has responded to call of the government to stay at home.Offline retail stores have been severely affected.Therefore,in order to transform a traditional offline sales model to the B2C model and to improve the shopping experience,this study aims to utilize historical sales data for exploring,building sales prediction and recommendation models.A novel data science life-cycle and process model with Recency,Frequency,and Monetary(RFM)analysis method with the combination of various analytics algorithms are utilized in this study for sales prediction and product recommendation through user behavior analytics.RFM analysis method is utilized for segmenting customer levels in the company to identify the importance of each level.For the purchase prediction model,XGBoost and Random Forest machine learning algorithms are used to build prediction models and 5-fold Cross-Validation method is utilized to evaluate their.For the product recommendation model,the association rules theory and Apriori algorithm are used to complete basket analysis and recommend products according to the outcomes.Moreover,some suggestions are proposed for the marketing department according to the outcomes.Overall,the XGBoost model achieved better performance and better accuracy with F1-score around 0.789.The proposed recommendation model provides good recommendation results and sales combinations for improving sales and market responsiveness.Furthermore,it recommend specific products to new customers.This study offered a very practical and useful business transformation case that assists companies in similar situations to transform their business models.展开更多
Trans-4- (N-2-hydroxyethyl-N-ethyl amino)-4ˊ-(diethyl amino)stilbene (DEAHAS) has been synthesized and characterized by 1H NMR, IR and elemental analysis. Linear absorption, single-photon induced fluorescence and tw...Trans-4- (N-2-hydroxyethyl-N-ethyl amino)-4ˊ-(diethyl amino)stilbene (DEAHAS) has been synthesized and characterized by 1H NMR, IR and elemental analysis. Linear absorption, single-photon induced fluorescence and two-photon induced fluorescence are experimentally studied. DEAHAS has an effective two-photon absorption cross-sections ofσ2 = 1.19×10-46 cm4·s/photon at 532 nm by using an open aperture Z-scan technique and exhibits a strong two-photon induced blue fluorescence of 430 nm when pumped with 800 nm laser irradiation.展开更多
Three dye-doped polymer rods in different matrices were synthesized in which weak hydrogen bond, strong hydrogen bond and covalent bond existed between the dye and the polymer chain. And the two-photon up-conversion...Three dye-doped polymer rods in different matrices were synthesized in which weak hydrogen bond, strong hydrogen bond and covalent bond existed between the dye and the polymer chain. And the two-photon up-conversion luminescent properties of HMASPS and HEASPS1 in three different microenvironments were studied.展开更多
We present our efforts towards power scaling of Er:Lu_(2)O_(3)lasers at 2.85μm.By applying a dual-end diode-pumped resonator scheme,we achieve an output power of 14.1 W at an absorbed pump power of 59.7 W with a slop...We present our efforts towards power scaling of Er:Lu_(2)O_(3)lasers at 2.85μm.By applying a dual-end diode-pumped resonator scheme,we achieve an output power of 14.1 W at an absorbed pump power of 59.7 W with a slope efficiency of 26%.In a single-end pumped resonator scheme,an output power of 10.1 W is reached under 41.9 W of absorbed pump power.To the best of our knowledge,this is the first single crystalline mid-infrared rare-earth-based solid-state laser with an output power exceeding 10 W at room temperature.展开更多
Dynamic infrared thermal camouflage technology has attracted extensive attention due to its ability to thermally conceal targets in various environmental backgrounds by tuning thermal emission.The use of phase change ...Dynamic infrared thermal camouflage technology has attracted extensive attention due to its ability to thermally conceal targets in various environmental backgrounds by tuning thermal emission.The use of phase change materials(PCMs)offers numerous advantages,including zero static power,rapid modulation rate,and large emissivity tuning range.However,existing PCM solutions still encounter several practical application challenges,such as temperature uniformity,amorphization achievement,and adaptability to different environments.In this paper,we present the design of an electrically controlled metal-insulator-metal thermal emitter based on a PCM metasurface,and numerically investigate its emissivity tunability,physical mechanisms,heat conduction,and thermal camouflage performance across different backgrounds.Furthermore,the influence of the quench rate on amorphization was studied to provide a guidance for evaluating and optimizing device structures.Simulation results reveal that the thermal emitter exhibits a wide spectral emissivity tuning range between 8 and 14μm,considerable quench rates for achieving amorphization,and the ability to provide thermal camouflage across a wide background temperature range.Therefore,it is anticipated that this contribution will promote the development of PCM-based thermal emitters for practical dynamic infrared thermal camouflage technology with broad applications in both civilian and military domains.展开更多
Guided-wave-based structural health monitoring(SHM)technology is of great importance for real-time inspection of high-temperature structures.The fundamental shear horizontal(SH_(0))wave is believed to be an ideal wave...Guided-wave-based structural health monitoring(SHM)technology is of great importance for real-time inspection of high-temperature structures.The fundamental shear horizontal(SH_(0))wave is believed to be an ideal wave mode for developing SHM systems due to its nondispersive characteristics.However,currently very limited SH_(0)wave transducers can be used for SHM of high-temperature structures due to the limitation of materials.Herein,a novel YSr_(3)(PO_(4))_(3)(YSP)piezoelectric crystal in the space group I43d was grown.Experiments show that the face-shear piezoelectric coefficient d_(14)(d_(14)=d_(25)=d_(36))is 9.7 pC/N and varies little from 25 to 800℃.Then a beam-focused SH_(0)wave piezoelectric transducer is developed based on face-shear-mode YSP wafers.Both finite element simulations and experimental results indicate that the YSP-based transducer can excite pure SH_(0)wave and focus the wave energy along two opposite main directions.Especially,the obtained SH_(0)wave beam is highly concentrated with a small divergence angle of less than 30°,originating from the high working frequency range from 300 to 400 kHz.The excellent temperature stability of the as-grown YSP crystal makes the proposed SH_(0)wave piezoelectric transducer very suitable for SHM of high-temperature structures.展开更多
Two-dimensional(2D)XY ferromagnets have drawn pronounced interest in recent years,but the characteristic of easy-plane magnetization restricts their application in spintronics to some extent.Here,we propose a general ...Two-dimensional(2D)XY ferromagnets have drawn pronounced interest in recent years,but the characteristic of easy-plane magnetization restricts their application in spintronics to some extent.Here,we propose a general strategy for constructing multiferroic van der Waals heterostructures,aiming to achieve electrical control over the magnetic anisotropy in 2D XY ferromagnets.The validity of this strategy is verified by the heterostructure composed of ferromagnetic VBi_(2)Te_(4) and ferroelectric In_(2)Se_(3) monolayers.By manipulating the polarized states of In_(2)Se_(3),the VBi_(2)Te_(4) can be reversibly transformed between 2D XY and Heisenberg ferromagnets,characterized by the switching of easy magnetization axis between in-plane and out-of-plane directions.More interestingly,accompanied by the changes in magnetic anisotropy,the VBi_(2)Te_(4) also demonstrates a phase transition from a semiconductor to a half-metal state,which can be ascribed to the band alignment and interfacial charge transfer.The switchable magnetic and electronic properties enable the heterostructure to be utilized in nonvolatile memory and logic devices.Additionally,the half-metallicity and magnetocrystalline anisotropy energy of the heterostructure can be effectively tuned by biaxial strain.These findings not only pave the way for electrically nonvolatile control of 2D XY ferromagnet,but also facilitate the development of interfacial magnetoelectric physics and applications.展开更多
Disordered-structure crystals have drawn increasing attention as promising ultrashort laser material hosts owing to their broad linewidth.Herein,a novel disordered Nd:YSr_(3)(PO_(4))_(3)(Nd:YSP)crystal with good quali...Disordered-structure crystals have drawn increasing attention as promising ultrashort laser material hosts owing to their broad linewidth.Herein,a novel disordered Nd:YSr_(3)(PO_(4))_(3)(Nd:YSP)crystal with good quality was successfully grown via the Czochralski pulling technique.The absorption and fluorescence spectra of the Nd:YSP single crystal were recorded at ambient temperature.The maximum absorption cross section for Nd:YSP single crystal is found to be approximately 3.89×10^(-20) cm^(2).The stimulated emission cross section for Nd:YSP crystal at~1060 nm was determined to be 7.64×10^(20) cm^(2) with the full width half maximum value of 22 nm.The fluorescence lifetime of the Nd3+ions in the Nd:YSP crystal is fitted to be 288μs.Diode-pumped continuous-wave laser operation is firstly realized at approximately 1060 nm.The maximum output power value from the Nd:YSP crystal is 714 mW,corresponding to a slope efficiency of-12.8%.The results indicate that the Nd:YSP crystal with a disordered structure may be a promising disordered laser host.展开更多
Single-pixel imaging(SPI)can capture 2D images of the target with only a nonpixelated detector,showing promising application potential in nonvisible spectral imaging,low-photon imaging,lidar,and other extreme imaging ...Single-pixel imaging(SPI)can capture 2D images of the target with only a nonpixelated detector,showing promising application potential in nonvisible spectral imaging,low-photon imaging,lidar,and other extreme imaging fields.However,the imaging mechanism of traditional SPI makes it difficult to achieve high imaging speed,which is a primary barrier for its widespread application.To address this issue,in this work,we propose and demonstrate a novel high-speed 2D and 3D imaging scheme based on traditional SPI,termed time-resolved single-pixel imaging(TRSPI).Previous SPI works mainly utilize correlation between a stable target and iterative illumination masks to reconstruct a single image.In TRSPI,by further exploiting correlation information between a dynamic scene and every static mask,we can reconstruct a series of time-varying images of the dynamic scene,given the dynamic scene is repetitive or reproducible.Experimentally,we conducted 2D and 3D imaging on a rotating chopper with a speed of 4800 revolutions per minute(rpm),and imaging speeds up to 2,000,000 fps.It is believed that this technology not only opens up a novel application direction for SPI,but also will provide a powerful solution for high-speed imaging.展开更多
Lithium niobate(LiNbO_(3),LN)crystal is a multi-functional material with favorable piezoelectric,nonlinear optical and electro-optic properties.In this study,the electromechanical properties of the radial extensional(...Lithium niobate(LiNbO_(3),LN)crystal is a multi-functional material with favorable piezoelectric,nonlinear optical and electro-optic properties.In this study,the electromechanical properties of the radial extensional(RE)and the thickness extensional(TE)modes of the congruent LN are studied and the temperature dependent behaviors are revealed.The RE mode electromechanical coupling factors(kp)for the Y-and Z-oriented discs are calculated and found to be 3.8%and 24.7%,respectively,which are nearly the same as the experimental results of 3.8%and 25.2%,respectively.The maximum RE and thickness shear(TS)modes electromechanical coupling factors are obtained to be 47.6%and 68.5%for the Yx/25and Yx/167crystal cuts,respectively.The LN crystal possesses good temperature stability of the electromechanical coupling factors(RE and TE modes)from 20℃ to 500℃,where the variations of kp and kt for the Y-oriented discs are<8.0%and<1.8%,respectively.展开更多
Batch adsorption experiments were conducted to explore the adsorption of Cr(VI) in aqueous solutions by fl-FeOOH-coated sand. We investigated the key factors which affected the adsorption process such as adsorbent d...Batch adsorption experiments were conducted to explore the adsorption of Cr(VI) in aqueous solutions by fl-FeOOH-coated sand. We investigated the key factors which affected the adsorption process such as adsorbent dosage, initial pH, initial Cr(VI) ion concentration, contact time and temperature. The uptake of Cr(VI) was very rapid and 44.3%, 51.6%, 58.9% of the adsorption happened during the first 180minutes at 293K, 303K and 313K, respectively. The pseudo-second-order rate equation successfully described the adsorption kinetics. To study the adsorption isotherm, two equilibrium models, the Langmuir and Freundlich isotherms, were adopted. At 293K, 303K and 313K, the adsorption capacities obtained from the Langmuir isotherm were 0.060, 0.070 and 0.076 mg Cr(VI) per gram of the adsorbent, respectively. Thermodynamic parameters such as the change of energy, enthalpy and entropy were calculated using the equilibrium constants. The negative value of AGO and the positive value of △H^0 showed that the adsorption of Cr(VI) in aqueous solutions by β-FeOOH-coated sand was spontaneous, endothermic and occurred by physisorption.展开更多
Two-photon absorption (TPA) and frequency-upconversion properties of a new upconversion laser dye trans-4-[p-(N-hydroxyethyl-N-methyl-amino)styryl]-N-meth-ylpyridinium toluene-p-sulfonate (abbreviated to HMASPS) were ...Two-photon absorption (TPA) and frequency-upconversion properties of a new upconversion laser dye trans-4-[p-(N-hydroxyethyl-N-methyl-amino)styryl]-N-meth-ylpyridinium toluene-p-sulfonate (abbreviated to HMASPS) were reported in this note. The linear absorption, TPA, single-photon induced fluorescence, TPA induced fluorescence and TPA induced upconverted lasing spectra of HMASPS solution in dimethyl formamide (abbreviated to DMF) were measured at room temperature. The red shift for the central wavelength of TPA induced fluorescence peak, which was compared with that of the single-photon induced fluorescence peak, and the blue shift for that of TPA induced up-converted lasing compared with that of TPA induced fluorescence, were explained by using re-absorption effect. TPA peak was at 930 nm. There is an 11 nm blue shift for two-photon energy of TPA peak compared with the linear absorption peak. The molecular TPA cross-section σ’2 at1064 nm was measured to be 6.0×10-48 cm4 .s/photon by using the open展开更多
The yttrium calcium oxyborate crystal(YCa_(4)O(BO_(3))_(3),YCOB)has been actively studied for hightemperature piezoelectric sensing applications.In this work,the stability of electric properties of YCOB crystal anneal...The yttrium calcium oxyborate crystal(YCa_(4)O(BO_(3))_(3),YCOB)has been actively studied for hightemperature piezoelectric sensing applications.In this work,the stability of electric properties of YCOB crystal annealed in critical conditions(high-temperatures of 900-1100℃ with a low oxygen partial pressure of 4×10^(-6) atm for 24 h)was investigated and the recovery mechanism for the electrical resisitivity,dielectric permittivity and dielectric loss were studied,taking advantage of the X-ray photoelectron spectra and the first principle calculations.The electrical resistivity of the annealed YCOB crystal was slightly decreased when compared to the pristine counterpart,being(2-5)×10^(7) Ω·cm at 850C.The dielectric permittivity and dielectric loss were found to increase after annealing,showing recoverable behaviours after thermal treatment above 650℃ in air.The calculated vacancy formation energy indicates that the oxygen vacancy is the dominant defects in YCOB.The formation of oxygen vacancy weakens the chemical bonding strength between B(Ca or Y)and O atoms,introduces extra donor levels in the band gap,which excites the electrons to conduction band more easily thus enhances the electrical conductivity and dielectric loss.The recovered electrical properties are believed to be associated with the reduced vacancy defects at elevated temperatures in air.展开更多
文摘BACKGROUND Photoaging,a result of chronic sun exposure,leads to skin damage and pigmentation changes.Traditional treatments may have limitations in high-altitude areas like Yunnan Province.Intradermal Col Ⅰ injections stimulate collagen production,potentially improving skin quality.This study aims to assess the efficacy and safety of this treatment for photoaging.AIM To evaluate the efficacy and safety of intradermal typeΙcollagen(ColΙ)injection for treating photoaging.METHODS This prospective,self-controlled study investigated the impact of intradermal injections of ColΙon skin photodamage in 20 patients from the Yunnan Province.Total six treatment sessions were conducted every 4 wk±3 d.Before and after each treatment,facial skin characteristics were quantified using a VISIA skin detector.Skin thickness data were assessed using the ultrasound probes of the Dermalab skin detector.The Face-Q scale was used for subjective evaluation of the treatment effect by the patients.RESULTS The skin thickness of the right cheek consistently increased after each treatment session compared with baseline.The skin thickness of the left cheek significantly increased after the third through sixth treatment sessions compared with baseline.The skin thickness of the right zygomatic region increased after the second to sixth treatment sessions,whereas that of the left zygomatic region showed a significant increase after the fourth through sixth treatment sessions.The skin thickness of both temporal regions significantly increased after the fifth and sixth treatment sessions compared with baseline(P<0.05).These findings were also supported by skin ultrasound images.The feature count for the red areas and wrinkle feature count decreased following the treatment(P<0.05).VISIA assessments also revealed a decrease in the red areas after treatment.The Face-QSatisfaction with Facial Appearance Overall and Face-Q-Satisfaction with Skin scores significantly increased after each treatment session.The overall appearance of the patients improved after treatment.CONCLUSION Intradermal ColΙinjection improves photoaging,with higher patient satisfaction and fewer adverse reactions,and could be an effective treatment method for populations residing in high-altitude areas.
文摘In the diagnosis and treatment of plastic surgery,there are structural processing problems,such as positioning,moving,and reconstructing complex threedimensional structures.Doctors operate according to their own experience,and the inability to accurately locate these structures is an important problem in plastic surgery.Emerging digital technologies such as virtual reality,augmented reality,and three-dimensional printing are widely used in the medical field,particularly in plastic surgery.This article reviews the development of these three technical concepts,introduces the technical elements and specific applications required in plastic surgery,summarizes the application status of the three technologies in plastic surgery,and summarizes prospects for future development.
文摘Background: Coronary artery disease (CAD) is frequently observed in aging end-stage liver disease (ESLD) patients who require orthotopic liver transplantation (OLT). This situation is challenging for both the pa- tients and the medical staff. Methods: We retrospectively studied the case records of 26 ESLD patients with CAD who underwent OLT with total clamping of the inferior vena cava between 2014 and 2018. We analyzed the details of the pre-operative evaluation, intraoperative anesthetic management and post-operative prognosis of these patients. Results: All patients tolerated the anhepatic stage well. Post-reperfusion syndrome (PRS) was observed in 13 patients (50%) and 2 of them were severe but corrected well. ST-segment depression was frequently observed during the anhepatic stage and reperfusion stage. No mortality due to cardiac-related events occurred among the patients during hospitalization. OLT with the modi ed piggyback technique could successfully be performed in ESLD patients with mild and moderate CAD. Conclusions: A thorough evaluation and optimization of recipients, strict monitoring and optimized man-agement of circulation, knowledge of the complicated changes during OLT procedures, and strategies to ameliorate post-reperfusion syndrome favorite the outcomes.
基金This research is funded by the School of Computer Sciences,and Division of Research&Innovation,Universiti Sains Malaysia,Short Term Grant(304/PKOMP/6315435)granted to Pantea Keikhosrokiani.
文摘The COVID-19 has brought us unprecedented difficulties and thousands of companies have closed down.The general public has responded to call of the government to stay at home.Offline retail stores have been severely affected.Therefore,in order to transform a traditional offline sales model to the B2C model and to improve the shopping experience,this study aims to utilize historical sales data for exploring,building sales prediction and recommendation models.A novel data science life-cycle and process model with Recency,Frequency,and Monetary(RFM)analysis method with the combination of various analytics algorithms are utilized in this study for sales prediction and product recommendation through user behavior analytics.RFM analysis method is utilized for segmenting customer levels in the company to identify the importance of each level.For the purchase prediction model,XGBoost and Random Forest machine learning algorithms are used to build prediction models and 5-fold Cross-Validation method is utilized to evaluate their.For the product recommendation model,the association rules theory and Apriori algorithm are used to complete basket analysis and recommend products according to the outcomes.Moreover,some suggestions are proposed for the marketing department according to the outcomes.Overall,the XGBoost model achieved better performance and better accuracy with F1-score around 0.789.The proposed recommendation model provides good recommendation results and sales combinations for improving sales and market responsiveness.Furthermore,it recommend specific products to new customers.This study offered a very practical and useful business transformation case that assists companies in similar situations to transform their business models.
基金This work was supported by the National Natural Science Foundation of China (NNSFC, No. 20473048, 50272036, 50302005, 90206042)Key Project of Science & Technology Research of Ministry of Education (KPSTR)Specialized Research Fund for the Doctoral Program of Higher Education (SRFDP, No. 20020422057).
文摘Trans-4- (N-2-hydroxyethyl-N-ethyl amino)-4ˊ-(diethyl amino)stilbene (DEAHAS) has been synthesized and characterized by 1H NMR, IR and elemental analysis. Linear absorption, single-photon induced fluorescence and two-photon induced fluorescence are experimentally studied. DEAHAS has an effective two-photon absorption cross-sections ofσ2 = 1.19×10-46 cm4·s/photon at 532 nm by using an open aperture Z-scan technique and exhibits a strong two-photon induced blue fluorescence of 430 nm when pumped with 800 nm laser irradiation.
基金This work was supported by the grant for State Key Program of China.
文摘Three dye-doped polymer rods in different matrices were synthesized in which weak hydrogen bond, strong hydrogen bond and covalent bond existed between the dye and the polymer chain. And the two-photon up-conversion luminescent properties of HMASPS and HEASPS1 in three different microenvironments were studied.
基金supported by the National Natural Science Foundation of China(Nos.62175132,61605100,and 12174212)the Natural Science Foundation of Shandong Province(Nos.ZR2020MF116 and ZR2019MF061)the Young Scholars Program of Shandong University。
文摘We present our efforts towards power scaling of Er:Lu_(2)O_(3)lasers at 2.85μm.By applying a dual-end diode-pumped resonator scheme,we achieve an output power of 14.1 W at an absorbed pump power of 59.7 W with a slope efficiency of 26%.In a single-end pumped resonator scheme,an output power of 10.1 W is reached under 41.9 W of absorbed pump power.To the best of our knowledge,this is the first single crystalline mid-infrared rare-earth-based solid-state laser with an output power exceeding 10 W at room temperature.
基金Natural Science Foundation of Shandong Province(ZR2023QF078)Natural Science Foundation of Jiangsu Province(BK20230246)+1 种基金Shandong Higher School Youth Innovation Team Technology ProgramQilu Young Scholars Program of Shandong University。
文摘Dynamic infrared thermal camouflage technology has attracted extensive attention due to its ability to thermally conceal targets in various environmental backgrounds by tuning thermal emission.The use of phase change materials(PCMs)offers numerous advantages,including zero static power,rapid modulation rate,and large emissivity tuning range.However,existing PCM solutions still encounter several practical application challenges,such as temperature uniformity,amorphization achievement,and adaptability to different environments.In this paper,we present the design of an electrically controlled metal-insulator-metal thermal emitter based on a PCM metasurface,and numerically investigate its emissivity tunability,physical mechanisms,heat conduction,and thermal camouflage performance across different backgrounds.Furthermore,the influence of the quench rate on amorphization was studied to provide a guidance for evaluating and optimizing device structures.Simulation results reveal that the thermal emitter exhibits a wide spectral emissivity tuning range between 8 and 14μm,considerable quench rates for achieving amorphization,and the ability to provide thermal camouflage across a wide background temperature range.Therefore,it is anticipated that this contribution will promote the development of PCM-based thermal emitters for practical dynamic infrared thermal camouflage technology with broad applications in both civilian and military domains.
基金supported by the National Natural Science Foundation of China(12192212,12172310)the young elite scientists sponsorship program by CAST(YESS20210342)the Primary Research&Development Plan of Shandong Province(2019JZZY010313).
文摘Guided-wave-based structural health monitoring(SHM)technology is of great importance for real-time inspection of high-temperature structures.The fundamental shear horizontal(SH_(0))wave is believed to be an ideal wave mode for developing SHM systems due to its nondispersive characteristics.However,currently very limited SH_(0)wave transducers can be used for SHM of high-temperature structures due to the limitation of materials.Herein,a novel YSr_(3)(PO_(4))_(3)(YSP)piezoelectric crystal in the space group I43d was grown.Experiments show that the face-shear piezoelectric coefficient d_(14)(d_(14)=d_(25)=d_(36))is 9.7 pC/N and varies little from 25 to 800℃.Then a beam-focused SH_(0)wave piezoelectric transducer is developed based on face-shear-mode YSP wafers.Both finite element simulations and experimental results indicate that the YSP-based transducer can excite pure SH_(0)wave and focus the wave energy along two opposite main directions.Especially,the obtained SH_(0)wave beam is highly concentrated with a small divergence angle of less than 30°,originating from the high working frequency range from 300 to 400 kHz.The excellent temperature stability of the as-grown YSP crystal makes the proposed SH_(0)wave piezoelectric transducer very suitable for SHM of high-temperature structures.
基金supported by the National Natural Science Foundation of China(Grant No.12004137)the Taishan Scholar Program of Shandong Province(Grant No.ts20190939)+1 种基金the Natural Science Foundation of Shandong Province(Grant Nos.ZR2020QA052 and ZR2020ZD35)the Young Scholars Program of Shandong University(No.2018WLJH65).
文摘Two-dimensional(2D)XY ferromagnets have drawn pronounced interest in recent years,but the characteristic of easy-plane magnetization restricts their application in spintronics to some extent.Here,we propose a general strategy for constructing multiferroic van der Waals heterostructures,aiming to achieve electrical control over the magnetic anisotropy in 2D XY ferromagnets.The validity of this strategy is verified by the heterostructure composed of ferromagnetic VBi_(2)Te_(4) and ferroelectric In_(2)Se_(3) monolayers.By manipulating the polarized states of In_(2)Se_(3),the VBi_(2)Te_(4) can be reversibly transformed between 2D XY and Heisenberg ferromagnets,characterized by the switching of easy magnetization axis between in-plane and out-of-plane directions.More interestingly,accompanied by the changes in magnetic anisotropy,the VBi_(2)Te_(4) also demonstrates a phase transition from a semiconductor to a half-metal state,which can be ascribed to the band alignment and interfacial charge transfer.The switchable magnetic and electronic properties enable the heterostructure to be utilized in nonvolatile memory and logic devices.Additionally,the half-metallicity and magnetocrystalline anisotropy energy of the heterostructure can be effectively tuned by biaxial strain.These findings not only pave the way for electrically nonvolatile control of 2D XY ferromagnet,but also facilitate the development of interfacial magnetoelectric physics and applications.
基金Project supported by the National Natural Science Foundation of China(51872165)the Primary Research&Development Plan of Shandong Province(2019JZZY010313)。
文摘Disordered-structure crystals have drawn increasing attention as promising ultrashort laser material hosts owing to their broad linewidth.Herein,a novel disordered Nd:YSr_(3)(PO_(4))_(3)(Nd:YSP)crystal with good quality was successfully grown via the Czochralski pulling technique.The absorption and fluorescence spectra of the Nd:YSP single crystal were recorded at ambient temperature.The maximum absorption cross section for Nd:YSP single crystal is found to be approximately 3.89×10^(-20) cm^(2).The stimulated emission cross section for Nd:YSP crystal at~1060 nm was determined to be 7.64×10^(20) cm^(2) with the full width half maximum value of 22 nm.The fluorescence lifetime of the Nd3+ions in the Nd:YSP crystal is fitted to be 288μs.Diode-pumped continuous-wave laser operation is firstly realized at approximately 1060 nm.The maximum output power value from the Nd:YSP crystal is 714 mW,corresponding to a slope efficiency of-12.8%.The results indicate that the Nd:YSP crystal with a disordered structure may be a promising disordered laser host.
基金Shandong Key Research and Development Programs(2019GGX104002,2020CXGC010104)Shandong University Inter-discipline Research Grant+1 种基金SinoGerman Center Mobility Programs(M-0044)Shandong Joint Funds of Natural Science(ZR2019LLZ003-1)。
文摘Single-pixel imaging(SPI)can capture 2D images of the target with only a nonpixelated detector,showing promising application potential in nonvisible spectral imaging,low-photon imaging,lidar,and other extreme imaging fields.However,the imaging mechanism of traditional SPI makes it difficult to achieve high imaging speed,which is a primary barrier for its widespread application.To address this issue,in this work,we propose and demonstrate a novel high-speed 2D and 3D imaging scheme based on traditional SPI,termed time-resolved single-pixel imaging(TRSPI).Previous SPI works mainly utilize correlation between a stable target and iterative illumination masks to reconstruct a single image.In TRSPI,by further exploiting correlation information between a dynamic scene and every static mask,we can reconstruct a series of time-varying images of the dynamic scene,given the dynamic scene is repetitive or reproducible.Experimentally,we conducted 2D and 3D imaging on a rotating chopper with a speed of 4800 revolutions per minute(rpm),and imaging speeds up to 2,000,000 fps.It is believed that this technology not only opens up a novel application direction for SPI,but also will provide a powerful solution for high-speed imaging.
基金the Primary Research&Development Plan of Shandong Province(2017CXGC0413)the National Natural Science Foundation of China(Grant No.51872165).
文摘Lithium niobate(LiNbO_(3),LN)crystal is a multi-functional material with favorable piezoelectric,nonlinear optical and electro-optic properties.In this study,the electromechanical properties of the radial extensional(RE)and the thickness extensional(TE)modes of the congruent LN are studied and the temperature dependent behaviors are revealed.The RE mode electromechanical coupling factors(kp)for the Y-and Z-oriented discs are calculated and found to be 3.8%and 24.7%,respectively,which are nearly the same as the experimental results of 3.8%and 25.2%,respectively.The maximum RE and thickness shear(TS)modes electromechanical coupling factors are obtained to be 47.6%and 68.5%for the Yx/25and Yx/167crystal cuts,respectively.The LN crystal possesses good temperature stability of the electromechanical coupling factors(RE and TE modes)from 20℃ to 500℃,where the variations of kp and kt for the Y-oriented discs are<8.0%and<1.8%,respectively.
文摘Batch adsorption experiments were conducted to explore the adsorption of Cr(VI) in aqueous solutions by fl-FeOOH-coated sand. We investigated the key factors which affected the adsorption process such as adsorbent dosage, initial pH, initial Cr(VI) ion concentration, contact time and temperature. The uptake of Cr(VI) was very rapid and 44.3%, 51.6%, 58.9% of the adsorption happened during the first 180minutes at 293K, 303K and 313K, respectively. The pseudo-second-order rate equation successfully described the adsorption kinetics. To study the adsorption isotherm, two equilibrium models, the Langmuir and Freundlich isotherms, were adopted. At 293K, 303K and 313K, the adsorption capacities obtained from the Langmuir isotherm were 0.060, 0.070 and 0.076 mg Cr(VI) per gram of the adsorbent, respectively. Thermodynamic parameters such as the change of energy, enthalpy and entropy were calculated using the equilibrium constants. The negative value of AGO and the positive value of △H^0 showed that the adsorption of Cr(VI) in aqueous solutions by β-FeOOH-coated sand was spontaneous, endothermic and occurred by physisorption.
基金The authors would like to thank Yang Zhaohe for the measurement of spectrum This work was supported by the State Key Program of China.
文摘Two-photon absorption (TPA) and frequency-upconversion properties of a new upconversion laser dye trans-4-[p-(N-hydroxyethyl-N-methyl-amino)styryl]-N-meth-ylpyridinium toluene-p-sulfonate (abbreviated to HMASPS) were reported in this note. The linear absorption, TPA, single-photon induced fluorescence, TPA induced fluorescence and TPA induced upconverted lasing spectra of HMASPS solution in dimethyl formamide (abbreviated to DMF) were measured at room temperature. The red shift for the central wavelength of TPA induced fluorescence peak, which was compared with that of the single-photon induced fluorescence peak, and the blue shift for that of TPA induced up-converted lasing compared with that of TPA induced fluorescence, were explained by using re-absorption effect. TPA peak was at 930 nm. There is an 11 nm blue shift for two-photon energy of TPA peak compared with the linear absorption peak. The molecular TPA cross-section σ’2 at1064 nm was measured to be 6.0×10-48 cm4 .s/photon by using the open
基金financially supported by the Primary Research&Development Plan of Shandong Province(2017CXGC0413)the National Natural Science Foundation of China(51872165).
文摘The yttrium calcium oxyborate crystal(YCa_(4)O(BO_(3))_(3),YCOB)has been actively studied for hightemperature piezoelectric sensing applications.In this work,the stability of electric properties of YCOB crystal annealed in critical conditions(high-temperatures of 900-1100℃ with a low oxygen partial pressure of 4×10^(-6) atm for 24 h)was investigated and the recovery mechanism for the electrical resisitivity,dielectric permittivity and dielectric loss were studied,taking advantage of the X-ray photoelectron spectra and the first principle calculations.The electrical resistivity of the annealed YCOB crystal was slightly decreased when compared to the pristine counterpart,being(2-5)×10^(7) Ω·cm at 850C.The dielectric permittivity and dielectric loss were found to increase after annealing,showing recoverable behaviours after thermal treatment above 650℃ in air.The calculated vacancy formation energy indicates that the oxygen vacancy is the dominant defects in YCOB.The formation of oxygen vacancy weakens the chemical bonding strength between B(Ca or Y)and O atoms,introduces extra donor levels in the band gap,which excites the electrons to conduction band more easily thus enhances the electrical conductivity and dielectric loss.The recovered electrical properties are believed to be associated with the reduced vacancy defects at elevated temperatures in air.