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Changing vegetation affects microclimates, groundwater tables, desertification, and biodiversity at the landscape level. The objective of this study is to assess the land cover dynamics and local perception of the influence of land use on vegetation change in Katsina State, Nigeria. Remote sensing and Geographic Information System (GIS)-based analysis, key informant interviews, and a semi-structured questionnaire covering 400 households were used to examine the driving forces behind vegetation change across Katsina State. As a result of the household survey, 86.5% (n = 400) of respondents reported a decline in vegetation in the study area, aligning with the Land Use Land Cover analysis phase of the study. The key drivers behind the observed vegetation depletion in the study area include firewood collection, charcoal production, and population growth. There has been an increasing awareness that education has emerged as one of the most significant socioeconomic factors influencing respondents' perceptions of these drivers. In spite of this, the unsustainable vegetation changes observed in this study have a negative impact on rural livelihoods and the management of natural resources in rural areas. This study recommends the implementation of sustainable land use policies that promote land-use practises that support economic growth and development.

During the past decade, interest has grown significantly in developing ultrasensitive widefield diamond magnetometry for various applications. Despite attempts to improve the adoption of conventional frame-based sensors, achieving high temporal resolution and sensitivity simultaneously remains a key challenge. This is largely due to the transfer and processing of massive amounts of sensor data to capture the widefield fluorescence intensity changes of spin defects in diamonds. In this study, we adopt a neuromorphic vision sensor to address this issue. This sensor pre-processes the detected signals in optically detected magnetic resonance (ODMR) measurements for quantum sensing, employing a working principle that closely resembles the operation of the human vision system. By encoding the changes of light intensity into spikes, this approach results in a vast dynamic range, high temporal resolution, and exceptional signal-to-background ratio. After a thorough evaluation of theoretical feasibility, our experiment with an off-the-shelf event camera demonstrated a 13x improvement in temporal resolution with comparable precision of detecting ODMR resonance frequencies compared with the state-of-the-art highly specialized frame-based approach. A specialized camera system with the same mechanism has the potential to enhance these benefits further. This performance improvement is primarily attributable to orders of magnitude smaller data volumes and, thus, reduced latency. We further showcase the deployment of this technology in monitoring dynamically modulated laser heating of gold nanoparticles coated on a diamond surface, a recognizably difficult task using existing approaches. The current development provides new insights for high-precision and low-latency widefield quantum sensing, with possibilities for integration with emerging memory devices for more efficient event-based data processing., Comment: 21 pages, 4 figures

Highly effective photothermal conversion performance coupled with high resolution temperature detection in real time is urgently needed for photothermal therapy (PTT). Herein, ultra-small Cu2S nanoparticles (NPs) were designed to absorb on the surface of NaScF4: Yb3+/Er3+/Mn2+@NaScF4@SiO2 NPs to form a central-satellite system, in which the Cu2S NPs play the role of providing significant light-to-heat conversion ability and the Er3+ ions in the NaScF4: Yb3+/Er3+/Mn2+ cores act as a thermometric probe based on the fluorescence intensity ratio (FIR) technology operating in the biological windows. A wavelength of 915 nm is used instead of the conventional 980 nm excitation wavelength to eliminate the laser induced overheating effect for the bio-tissues, by which Yb3+ can also be effectively excited. The temperature resolution of the FIR-based optical thermometer is determined to be better than 0.08 K over the biophysical temperature range with a minimal value of 0.06 K at 298 K, perfectly satisfying the requirements of biomedicine. Under the radiation of 915 nm light, the Cu2S NPs exhibit remarkable light-to-heat conversion capacity, which is proved by photothermal ablation testing of E. coli. The results reveal the enormous potential of the present NPs for PTT integrated with real-time temperature sensing with high resolution.

Monoclinic ZrO2 (m-ZrO2) is an attractive material for photonic applications due to its low site symmetry and phonon energy. In this paper, we present detailed studies on the luminescence properties of Ti4+ and Eu3+ in m-ZrO2. In view of the continuing controversy over the origin of “intrinsic” white-blue luminescence in pristine m-ZrO2, more spectroscopic information obtained by characterizing m-ZrO2 intentionally doped with Ti4+, Ti3+ and other metal ions and extensive discussions on the general characteristics of different luminescence processes were provided to evidence the luminescence as the Ti3+ → O− charge transfer transition in the [Ti(IV)O7]10− complex due to the trace amount of Ti4+ impurity in ZrO2 reagent. Competitive absorption was observed between host exciton and oxygen–metal charge transfer processes (O2−–Ti4+, O2−–Eu3+), and even between the two types of charge transfer process because of the sharing of electrons at the top of the valence band, which greatly influenced the absorption and excitation processes. The spectral components comprising the broad excitation band of O2−–Ti4+ white-blue or Eu3+ red emissions in different phosphors were identified, and their evolutions with doping concentration were explained. The energy state locations of oxygen defects produced by intrinsic charge compensation in m-ZrO2:Eu3+ were proposed to be ∼2.41 eV above the top of the valence band by using Eu3+ for the luminescent probe. Efficient energy transfer from the [Ti(IV)O7]10− complex to Eu3+ was first observed in m-ZrO2:Ti4+,Eu3+ phosphors, which were demonstrated to be high performance ratiometric self-referencing optical thermometric materials based on the dual-emitting combination strategy, with the relative sensitivity amounting to ∼3.84% K−1. Optical thermometry not only covering the physiological temperature range but also with high relative sensitivity could be achieved upon appropriate doping.

The indispensable broad-band red phosphors for LED lighting generally show a long emission tail for wavelengths longer than 650 nm, which consumes excitation energy but contributes little luminance. Here, we report, for the first time, a broad red emission band with a steep falling edge at 652 nm, formed of widely distributed 1D2 → 3H4 emission lines of Pr3+ in Y3Si6N11 due to a large Stark splitting of the 3H4 (930 cm-1) and 1D2 (725 cm-1) levels. The red emission exhibits a 43 nm bandwidth, which is the widest in Pr3+-doped phosphors reported so far. The red Y3Si6N11:Pr3+ phosphor was applied for the fabrication of 310 nm UV chip-based white LEDs, and a high color rendering index of 96 at a low correlated color temperature of 4188 K was achieved. Furthermore, a temperature-sensing scheme was proposed based on the temperature-dependent intensity ratios of the emission lines from the thermally coupled and large Stark splitting levels of the 1D2 state. Relative sensitivities as a function of temperature were studied in the range of 93-473 K. The findings of this study indicate that Y3Si6N11:Pr3+ is an attractive broad-band red phosphor for both high color rendering white LEDs and temperature sensing applications.

As phosphor-converted white light emitting diodes have emerged as new-generation light sources, developing phosphors with both high quantum efficiency (QE) and thermal stability is urgently required. One of the effective strategies is exploiting the nonradiative energy transfer to simultaneously improve the absorption of the activator and tune the emission of the sensitizer. In this work, we report a series of color-tunable phosphors by constructing an energy transfer system by co-doping Ce3+ and Tb3+ into Ca3Gd2Si6O18 (CGSO). We show that CGSO:Ce3+,Tb3+ not only exhibits color-tunable emission from violet (395 nm) to green (543 nm), but also possesses high internal QE (90.1%). Furthermore, we demonstrate that thermal stability can be significantly improved via efficient energy transfer from Ce3+ to Tb3+, which is mainly attributed to the fast energy transfer within the nearest Ce3+–Tb3+ pairs. Our results indicate that energy transfer from Ce3+ to Tb3+ provides a promising way to develop new green phosphors with high QE and superior thermal stability.

Developing a conceptual “write”/“read” technology for optical information storage of persistent phosphors is necessary but often underestimated. Here we demonstrate a “write”/“read” approach of traps upon illumination by using a blue light-emitting diode (LED) in persistent phosphors such as LaMgGa11O19:Cr3+. Our investigation indicates that the phosphor can be charged upon high-power illumination (e.g., incident power density of 0.5 W cm−2) but discharged upon low-power illumination (e.g., 0.1 W cm−2). An appealing feature of the present approach is that the charging and discharging share the same illumination wavelength, which offers an interesting technical advantage and apparent convenience for applications. Moreover, such a manipulation technique is generally applicable for many existing phosphors.

Carrier dynamics between singlet fission molecules and a perovskite were studied using transient absorption measurements on TIPS-pentacene/CH3NH3PbI3 (MAPbI3) bilayer, pristine MAPbI3 and TIPS-pentacene films. Ultrafast electron transfer within 1.5 ps is verified to proceed directly from the correlated bound triplet pair states of TIPS-pentacene generated by a singlet fission process to the MAPbI3 conduction band. Hole transfer from MAPbI3 to TIPS-pentacene proceeds on a much longer time scale of tens of ns. Our study not only unveils the charge carrier dynamics in a singlet fission molecule/perovskite bilayer structure, but also provides new insights on the design of singlet fission sensitized perovskite solar cells with enhanced performance.

SLC13A4 is a sodium sulfate co-transporter, which is expressed in brains, placentas, thymes and other tissues, plays an essential role in maintaining the metabolic balance of sulfate in vivo. The TCGA database shows that it is differentially expressed in a variety of tumors, but its prognostic value in tumors has not been clarified. TCGA, Oncomine and Timer databases were used to analyze SLC13A4 mRNA expression in cancer tissues and normal tissues, and its correlation with clinical prognosis in head and neck tumor. The CIBERSORT database was used to analyze the correlation between SLC13A4 expression and the infiltration of immune cells. SLC13A4 enrichment analysis was carried out by GSEA. SLC13A4 mRNA levels were significantly lower in head and neck tumors than in paracancer tissues. SLC13A4 expression in Head and neck squamous cell carcinoma (HNSCC) was closely related to tumor pathological grade and clinical stage. Decreased SLC13A4 expression was associated with poor overall survival (OS), progression free survival (PFS), disease specific survival (DSS) and recurrence free survival (RFS) in HNSCC patients. The expression of SLC13A4 was negatively correlated with Monocytes, M1 macrophages, M2 macrophages, resting CD4+ memory T cells, resting NK cells and activated NK cells, but positively correlated with neutrophils, plasma cells, T follicular helper cells, gamma delta T cells, regulatory T cells and naive B cells. In addition, the genes in SLC13A4 low-expression group were mainly concentrated in immunity-related activities, viral diseases, typical tumor pathways and metabolism. The SLC13A4 high expression group was mainly enriched in metabolic pathways. These suggest that SLC13A4 may be a potential prognostic biomarker in HNSC and correlated with immune infiltrates.

Femtosecond optical pump–probe spectroscopy is employed to elucidate the ultrafast carrier nonradiative relaxation dynamics of bare GaAs and a core–shell GaAs/AlGaAs semiconductor nanowire array. Different from the single nanowire conventionally used for the study of ultrafast dynamics, a simple spin coating and peeling off method was performed to prepare transparent organic films containing a vertical oriented nanowire array for transient absorption measurement. The transient experiment provides the direct observation of carrier thermalization, carrier cooling, thermal dissipation and band-gap energy evolutions along with the carrier relaxations. Carrier thermalization occurs within sub-0.5 ps and proceeds almost independently on the AlGaAs-coating, while the time constants of carrier cooling and thermal dissipation are increased by an order of magnitude due to the AlGaAs-coating effect. The concomitant band-gap evolutions in GaAs and GaAs/AlGaAs include an initial rapid red-shift in thermalization period, followed by a slow blue and/or red shift in carrier cooling, and then by an even slower blue shift in thermal dissipation. The evolution is explained by the competition of band-gap renormalization, plasma screening and band-filling. These findings are significant for understanding the basic physics of carrier scattering, and also for the development of flexible optoelectronic devices.

If there is the uncertain travel time in the material supply of a JIT assembly line, a shortage of material in the station will be caused, which has an important impact on production. In this paper, the uncertain travel time is represented by the interval number according to the actual situation. By using robust optimization method and introducing a route-dependent the uncertain parameter, the uncertain travel time is considered into the material supply optimization model for minimizing the largest possible vehicle trip time. A genetic algorithm is designed to solve this model. Through the analysis of the relationship between the line stoppage probability and the route-dependent the uncertain parameter, by the Monte Carlo simulation, the final solution can be obtained. The material supply planning for an engine assembly line is taken an example. The solution which can resist the uncertain travel time is gained by using the proposed method; hence the effectiveness of the method is proved.

The Ba3Y4O9 host matrix with a low cutoff phonon energy of 585 cm−1 is first applied to upconversion (UC) luminescence (UCL) by codoping Er3+/Yb3+. The new phosphor shows an intense red UC emission which is 6.8-fold and 5.9-fold stronger than that of Y2O3 and β-NaYF4, respectively, under 980 nm GaAs laser diode (LD) excitation at a low density. A broad absorption band centered at 976 nm is observed, meaning a high adaptability to the GaAs LD required in actual applications. The optical thermometry behaviors based on the temperature dependent fluorescence intensity ratios of thermally coupled green UC bands 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 as well as the thermally coupled red UC emission bands originating from the Stark sublevels of 4F9/2 manifold have been explored. The results show that green emissions are suitable for temperatures above 350 K with the maximum sensitivity of 0.00248 K−1 at 563 K and the red emissions are appropriate for temperatures below 350 K with the maximum sensitivity of 0.00371 K−1 at 143 K in our experimental range, indicating their complementary temperature sensing ranges. Moreover, a new method is proposed for evaluating the radiative lifetime of the Er3+ 4F9/2 state based on the analysis of photoluminescence (PL) spectra and fluorescence decay curves. The radiative lifetime of 879 μs for the red emitting level in Ba3Y4O9 is achieved. Thereby, the emission efficiency of 4F9/2 in the new UCP is a little higher than that in Y2O3. Our results imply that Ba3Y4O9:Er3+/Yb3+ is a promising UCP, which could be applied to wide scope optical thermometry using a dual-color scheme.

The garnet Ca2LuZr2Al3O12 (CLZA) is a promising broad-band NIR phosphor for blue LED chips when it is doped with Cr3+. The photoelectric efficiency of the pc-LED fabricated from CLZA:Cr3+ and a 460 nm LED chip, in the 750–820 nm spectral range, was 4.1%, which was superior to the efficiency of a tungsten lamp (2.9%). In CLZA’s structure, Cr3+ occupied Ca2+/Lu3+ and Zr4+ sites and showed two luminescence centers. The crystal strength parameters of Ce3+ and Cr3+ were calculated to show the coordination environment of the dodecahedral and octahedral sites in CLZA. Low absorbance of Cr3+ was the main constraint on quantum efficiency. Ce3+ was thus introduced as a sensitizer to improve the absorbance. An efficient energy transfer process can be observed between Ce3+ and Cr3+ in CLZA. The temperature dependent properties of CLZA:Cr3+ were also studied. Two thermal processes (thermal quenching and thermal ionization) were observed and discussed in detail.

The most common yellow phosphor for wLEDs, Y3Al5O12:Ce3+ (YAG:Ce3+), suffers from a deficiency of red in its spectral content of light. In this paper, a new strategy is provided to tailor the Ce3+ spectral profile through surface-located dye molecules of ATTO-Rho101, which feature intense, broad absorption in the green-yellow spectral region of Ce3+ emission as well as bright red emission. Sphere-shaped and highly dispersed micrometer and nanometer-sized YAG:Ce3+ (micro/nano-YAG:Ce3+) was synthesized through a modified solvothermal method. Surface SiO2 coating and simultaneous dye embedding were performed on the solvothermally derived YAG:Ce3+, heat-treated micro-YAG:Ce3+ and commercial phosphors. Efficient radiative transfer/reabsorption from Ce3+ in the inner core of YAG to the dye molecules in the SiO2 outer shell, irrespective of the size of the phosphors, was demonstrated in the accumulated YAG:Ce3+@SiO2 + dye powder upon blue light excitation; this enhanced its red emission. Fluorescence microscopy was demonstrated to be a powerful tool to identify the reabsorption phenomenon of the powdered materials. Packaging the heat-treated micro-YAG:Ce3+@SiO2 + dye phosphors on blue LED chips yielded a warm wLED (Ra∼ 93), but an Ra of only ∼79 was obtained for the wLED with commercial YAG:Ce3+@(SiO2 + dye)5 due to the low concentration of phosphors dispersed in the epoxy resin and the resulting decreased reabsorption by dye molecules. Surface-protonated amine species were found to induce Ce3+→ Ce4+ oxidation upon activation by heating or photoirradiation and then quench the photoluminescence (PL) of micro-YAG:Ce3+ even after surface modification by SiO2, YAG or being embedded in an epoxy resin matrix. High calcination temperatures greatly improved the PL stability of micro-YAG:Ce3+ through the removal of surface-capped species. The dye in the silica matrix showed high stability against heating and irradiation due to the so-called "caging effects"; however, decreased photo-stability was found in commercial YAG:Ce3+@(SiO2 + dye)5 due to the incomplete and/or loose SiO2 layer grown during multiple surface modifications.

Green phosphors codoped with Ce3+ and Tb3+ have been studied extensively for application in UV-based white LEDs, but only few of them show both high luminescence efficiency and thermal stability. This study reports a new green phosphor of Ce3+ and Tb3+-codoped Ba2Lu5B5O17 prepared by a solid-state reaction. Emission color tuning from blue to green was studied as a function of Tb3+ concentration under UV excitation and well-described based on energy transfer from Ce3+ to Tb3+. The Tb3+ emission endowed the green phosphor with a high quantum yield of 86%, and a high thermal stability over the 303–483 K range was achieved. A model has been proposed to explain a general phenomenon observed in Ce3+ and Tb3+-codoped phosphors that Tb3+ emission is thermally more stable than the Ce3+ emission. A relationship between the temperature dependencies of Tb3+ and Ce3+ emissions was obtained in connection with room temperature energy transfer efficiency. The thermally stable Tb3+ emission was well-predicated using the obtained relationship. The new phosphor was employed for fabricating a UV-based white LED. A high color-rendering index of 91.4 at a low correlated color temperature of 3809 K is obtained, indicating promising application of Ba2Lu5B5O17:Ce3+,Tb3+ in solid-state lighting.

The Y3Si6N11:Ce3+ yellow phosphor shows a well-known ∼150 nm broad emission band, exhibiting a potential application in UV or blue based white LEDs. We report the observation of two Ce3+ emitting centers, the superposition of which forms the broad emission band. One center has a green emission band peaked at 539 nm (Ce1) with the first excitation band at 420 nm. The other has a red emission band peaked at 600 nm (Ce2) with the first excitation band at 485 nm. The two Ce3+ centers are assigned to the substitution for two Y sites in Y3Si6N11. It was found that the Ce2 emission intensity is continuously enhanced relative to that of Ce1 with an increasing Ce3+ concentration, thus leading to a redshift of the broadband. Meanwhile, a more notable fluorescence lifetime shortening of Ce1 compared to Ce2 with an increasing Ce3+ concentration was observed. These results suggest the occurrence of energy transfer from Ce1 to Ce2. The temperature-dependent luminescence intensity of Y3Si6N11:Ce3+ was also studied in the range of 93 to 473 K.

Assembly line balancing and sequencing are two main problems in the planning of a mixed-model assembly line. In recent years, the un-paced buffered mixed-model assembly line with buffers between workstations has been widely used in industry. In order to solve the balancing and sequencing problem and ensure the efficient operation of the assembly line, an integrated method for the balancing and sequencing of unpaced buffered mixed-model assembly line is proposed. A combined precedence diagram is used to transform the mixedmodel assembly line balancing problem into a single model balancing problem. The objective of the balancing problem is to minimize cycle time under given the number of the workstations. A combined priority rule is adopted to find a solution. Based on the result of the balancing problem, the NEH (Nawaz-Enscore-Ham) algorithm is implemented for the sequencing problem to minimize the makespan considering the blocking owing to the buffers. The effectiveness of the method is verified by three cases.

Based on the analysis of the equivalent models of the traction transformer and the train in the existing metro power supply system (MPSS), this paper embeds the coupling relation between the metro traction power supply system (MTPSS) and the train operation into the model and combines with the corresponding range of the output current, the voltage and the resistance of the 6 section type equivalent external characteristic curve of the 12-pulse rectifier unit to research and design the AC/DC power flow calculation method for the MPSS, this paper analyzes the operation efficiency and the power flow calculation error of the method. The result shows that this method can effectively improve the accuracy of the power flow value calculation and has the advantages of the fast calculation speed and the good real-time performance, besides the model can describe coupling relations between the train and traction network more accurately.

The coupling relation between the Metro Traction Power Supply System (MTSPS) and the Metro Train Traction Drive System (MTTDS) was rarely considered in the existing Metro Traction Power Supply Simulation System (MTSPSS), so the system could not describe the train-network real-time electrical coupling phenomenon of multi-train operation on the actual line of the metro site accurately and effectively. Therefore, in this paper, the trains model are added into the MTSPS to build a train-network simulation model of the MTSPS, combining the traction characteristic of the MTTDS and the relation of train-network, then this paper analyses the influence of the trains on the Traction Power Supply Network (TPSN) and the TPSN on the trains performance, and discusses what effect the multi-train operation and the different departure intervals have on the whole traction network voltage fluctuation. The experimental results indicates that the train-network coupling model built in this paper can describe the coupling relation between the trains and the traction network in the actual system of metro more accurately, which has some certain guidance functions on the capacity design of the MTSPS and the schedule of the timetable.

Leaf area index (LAI) is a crucial variable in all kinds of ecosystem, climate and crop yield models, describing the fluxes of energy, mass and momentum between the surface and the planetary boundary layer. To accurately determine the corn LAI, several methods of LAI, estimation have been evaluated in this investigation, including vegetation indices, principal component analysis (PCA), the neural network method (NN), the look-up table (LUT) inversion from PROSAIL model and the Hybrid model. Comparisons were conducted based on field-measured corn canopy hyperspectral reflectance and LAI data over northeastern China. In order to fairly compare the LAI estimation performance of different methods, the ground-measured data were separated into two sets (modeling data and validation data), except the LUT and hybrid methods of PROSAIL-based. The results indicated that the PCA method delivered the best performance for corn LAI estimation (with maximum R-2=0.814 and minimum RMSE=0.501) in this study. The hybrid model and EVI provided moderate results. Comparatively, the LUT and NN methods were less successful and NDVI provided the worst corn LAI estimation performance in this study. The PCA method shows great potential for performing well on corn LAI estimation from hyperspectral information. PCA can avoid the reflectance saturation defect of dense canopy in a certain extent, can utilize hyperspectral reflectance data much more effectively than other methods, and is not limited by the band numbers, it can also reduce noise and provide an great correlation with LAI from the hyper-bands or the multi-bands reflectance. (C) 2011 Elsevier B.V. All rights reserved.

Plant phenology refers to the emergence of an annual cycle of natural phenomena in plants affected by climate and other environmental factors.Information of crop phenology can directly reflect the effect of temperature and precipitation on the crop,which is essential for evaluating crop growth,productivity and crop management.Remote sensing technique is an important method to detect vegetation phenology with high spatial-temporal scales.Vegetation index generated by infrared and near-infrared band based on satellite remotely sensed data can reflect the status of vegetation growth and coverage more accurately.The Northeast China includes Liaoning,Jilin and Heilongjiang provinces,which rice area accounts for about 10% of total rice area and its rice yield accounts for 11% of total rice yield in China.Rice planting in Northeast China plays an important role in China′s food safety.In this study,we developed a method for detecting phenological stages of rice in Northeast China based on the EOS-MODIS multi-temporal remote sensing data,including MOD09A1 and MCD12Q1 in 2008.The rice crop phenological stages were detected by using EOS-MODIS Enhanced Vegetation Index(EVI) data,and compared with the observed rice phenological stages in 24 selected agro-meteorological sites in Northeast China.The method consists of four procedures:(1) calculating the EVI value and extracting time profile from the location where 24 selected sites through MODIS-EVI data;(2) filtering the noise in EVI time profile by wavelet transform with twenty six types of wavelets;(3) identifying the rice planting date,heading date and ripening date by the variation characteristics in the smoothed EVI time profile;(4) comparing the result calculated by this method with the observed data from the 24 agro-meteorological sites in study area in 2008 and calculating the root mean square error(RMSE),then choosing the best type of wavelets.Due to the temporal resolution of the MODIS/Terra is 8 days,there will be missing data in the EVI time profile.The cubic spline interpolated(CSI) method(more smoother and stabler) was applied to repair the missing data,which can reflect the missing data more authentic.The twenty six types of wavelet: Daubechies(7—20),Coiflet(3—5) and Symlet(7—15) were used when filtering EVI time profile.The results showed that,the case using Symlet11 shows a remarkably good result in determining phenological stages,which is compared with the observed data.Most of the RMSE in planting date were less than 16 days.Most of the RMSE in heading date and ripening date were less than 8 days.It was shown that the Symlet11 filtering is the best method,which can be used to detect rice phenology in Northeast China.Furthermore,the Symlet11 filtering can be used to analyze variations and distribution of rice phenology with high-spatial scale in the whole Northeast China.

Triply doped Y_3Al_5O_(12):Ce~(3+),Pr~(3+),Cr~(3+)phosphors with Ce~(3+)and Pr~(3+)substituting for Y~(3+)sites and Cr~(3+)substituting for Al~(3+)site are prepared by solid state reaction.A broad emission spectrum composed a yellow emission band from Ce~(3+),a light red emission line from Pr~(3+)and a deep red emission line from Cr~(3+), which are generated through energy transfer among the dopant ions.The study of photoluminescence and fluorescence decay indicates that there exist energy transfers from Ce~(3+)→Cr~(3+)and Ce~(3+)→Pr~(3+)→Cr~(3+).The effect of energy transfer on relative intensities of the three emissions is analyzed.A white LED is fabricated using a blue LED chip coated with the triply doped phosphor and shows a color rendering index of 81.4 and 80.4, respectively.It is higher than that either using Ce~(3+)and Cr~(3+)doubly doped phosphor or Ce~(3+)singly doped phosphors.

Duan’s simple model is extended to analyze the mixing of the 4fN − 15d configuration with the 4fN states. The explicit static coupling and traditional dynamic coupling are considered, and the parameters are fitted according to the absorption spectrum in LiYF4: Nd3+. The parameter values obtained are as follows: T32 = −28i × 10−7, T52 = −1151i × 10−7, A322 = 192i × 10−12 cm, A524 = i × 10−12 cm, A726 = 54i × 10−12 cm, and A766 = −680i × 10−12 cm. Compared to the experimental measurements, the present model yields better results than those obtained from the Judd-Ofelt theory.

Although all normal tissue cells, including stem cells, are genetically homologous, variation in gene expression patterns has already determined the distinct roles for individual cells in the physiological process due to the occurrence of epigenetic modification. This is of special importance for the existence of tissue stem cells because they are exclusively immortal within the body, capable of self-replicating and differentiating by which tissues renew and repair itself and the total tissue cell population maintains a steady-state. Impairment of tissue stem cells is usually accompanied by a reduction in cell number, slows down the repair process and causes hypofunction. For instance, chemotherapy usually leads to depression of bone marrow and hair loss. Cellular aging is closely associated with the continuous erosion of the telomere while activation of telomerase repairs and maintains telomeres, thus slowing the aging process and prolonging cell life. In normal adults, telomerase activation mainly presents in tissue stem cells and progenitor cells giving them unlimited growth potential. Despite the extensive demonstration of telomerase activation in malignancy (> 80%), scientists found that heterogeneity also exists among the tumor cells and only minorities of cells, designated as cancer stem cells, undergo processes analogous to the self-renewal and differentiation of normal stem cells while the rest have limited lifespans. In this study, telomerase activity was measured and compared in breast cancer stem cells and non-stem cells that were phenotypically sorted by examining surface marker expression. The results indicated that cancer stem cells show a higher level of enzyme activity than non-stem cells. In addition, associated with the repair of cancer tissue (or relapse) after chemotherapy, telomerase activity in stem cells was markedly increased.

Daily actual evapotranspiration is estimated based on surface net radiation, vegetation index, average air temperature and daily air temperature range using satellite remote sensing data and routine meteorological data. Also, the estimated actual evapotranspiration (ET) is compared and validated with measured ET using eddy covariance method at luancheng station. Besides, the temporal and spatial variation of actual evapotranspiration and its impact factors are analysed qualitatively. According to the evapotranspiration through the ET model correlates well with the measured ET and the estimation is acceptable for assessing the drought conditions at large area of scales. In addition, the EDI anomaly can reflect a higher spatial resolution of drought pattern and is reliable in the indication and judgment of drought. Keywords-actual evapotranspiration; evapotranspiration drought index; North China; remote sensing

Yuanmousaurus jiangyiensis gen. et sp. nov. is erected based on an incomplete skeleton. It is characterized by more complex structures of the neural arches in the dorsal vertebrae than those in Omeisaurus, but less complex than those of Euhelopus; the dorsal vertebra bears 9 laminae, forming three cavities on the lateral surface of the neural arch; the dorsal vertebral neural spines with dorsoventrally-oriented cavities are similar to those of Omeisaurus and Patagosaurus. Yuanmousaurus is more primitive than Euhelopus, but more derived than Omeisaurus. The similar dorsal vertebral structure between Yuanmousaurus and Patagosaurus may indicate that they have a close relationship to each other.

The niobate phosphate glasses containing Eu3+ ions were fabricated by the melting method. The fluorescence characteristics of the glass at temperatures from 77 K to 700 K were investigated under the excitation of 488 nm light. The results show that the fluorescence intensity of Eu3+ ions first increases and then decreases as temperature increases. The temperature-dependent parameters of the crystal fields and the local structure surrounding Eu3+ ions were investigated and discussed from the situation of splitting energy level of 5D0-7F1. The results indicate that the distance of europium and oxygen become shorter with increasing temperature and the coordination number of Eu3+ ion is near 8, which does not change with temperature.

Using the multi-temporal Landsat data and survey data of national resources, the authors studied the dynamics of cultivated land and landcover changes of typical ecological regions in China. The results of investigation showed that the whole distribution of the cultivated land shifted to Northeast and Northwest China, and as a result, the ecological quality of cultivated land dropped down. The seacoast and cultivated land in the area of Yellow River Mouth expanded by an increasing rate of 0.73 km·a−1, with a depositing rate of 2.1 km·a−1. The desertification area of the dynamic of Horqin Sandy Land increased from 60.02% of the total land area in 1970s to 64.82% in 1980s but decreased to 54.90% in early 1990s. As to the change of North Tibet lakes, the water area of the Namu Lake decreased by 38.58 km2 from year 1970 to 1988, with a decreasing rate of 2.14 km2·a−1.

Basic structure and algorithm of leaf mechanism photosynthesis model were described in first part of this study based on former researcher results. Then, considering some environmental factors influencing on leaf photosynthesis, three numerical sensitivity experiments were carried out. We simulated the single leaf net CO2 assimilation, which acts as a function of different light, carbon dioxide and temperature conditions. The relationships between leaf net photosynthetic rate of C3 and C4 plant with CO2 concentration intercellular, leaf temperature, and photosynthetic active radiation (PAR) were presented, respectively. The results show the numerical experiment may indicate the main characteristic of plant photosynthesis in C3 and C4 plant, and further can be used to integrate with the regional climate model and act as land surface process scheme, and better understand the interaction between vegetation and atmosphere.

A theoretical description of shear instability is presented in a system of equations. It is shown that two types of instability may exist. One of them is dominated by pore pressure softening while the other by strain softening. A criterion combining pore pressure softening, strain hardening, and volume strain coefficient is obtained and practical implications are discussed.

The development of the shear bands of saturated soil in coupling-rate- and pore-pressure-dependent simple shear has been discussed, using a simple model and a matching technique at the moving boundary of a shear band. It is shown that the development of shear bands are dominated by the coupling-rate and pore-pressure effect of the material. The strength of the soil acts as a destabilizer, whilst pore pressure diffusion makes the band expand. The theory is discussed and some computational solutions have been presented.

A theoretical description of instability of saturated soil under axial load is presented with a set of equations describing the deformation based on the two-phase continuous media theory. It is shown that all parameters of water and soil influence the instability and two types of instability may exist. One of them is dominated by pore pressure softening, while the other by strain softening. Finally, a practical application is discussed.

The structural transition of bulk and nano-size Gd2O3:Eu are studied by high pressure energy disperse x-ray diffraction (XRD) and high pressure photoluminescence. Our results show that in spite of different size of Gd2O3 particles, the cubic structure turns into a possible hexagonal one above 13.4 GPa. When the pressure is released, the sample reverses to the monoclinic structure. No cubic structure presents in the released samples. That is to say, the compression and relaxation of the sample leads to the cubic Gd2O3:Eu then turns into the monoclinic one.

It is shown that uranium-238 together with its whole family of derived nuclides at equilibrium saturate concentration under reactor neutron flux irradiation constitute a new type of unstable nuclide series.

We report random lasing achieved in a MEH-PPV/glass waveguide with the TiO2 scatterers in diameter 20 nm that is significantly smaller than submicrometre of TiO2 scatterers in the films or suspensions previously reported on random lasing. The spectral lines are dramatically narrowed by almost two orders of magnitude compared with those excited by a xenon lamp. The amplified spontaneous emission is identified as the dominant mechanism in our system. Light localization might be achieved in a broad class of random materials based on the features of the mean free path l* = 5.4×105 nm, kl**>>1 and the Thouless number 6.73×10−5 with k being the wave number.

Optical waveguides and micro-mirrors have been successfully induced inside fused silica glass and k9 glass, respectively, by focusing a 800 nm femtosecond (fs) pulsed laser with a repetition rate of 1 kHz. The change of refractive index was determined to be 0.001-0.008 in the fused silica glass and 0.006 in the k9 glass. The refractive index change is dependent on both the dose of irradiation and the power density of the fs pulsed laser. Photoluminescence was observed in the irradiated region, and was attributed to the defects induced by fs laser irradiation. We discuss the relationship between the optical property and the luminescent property of the irradiated region.

When an automobile works on rapid steering condition, it tends to occur side slip and side tumbling under centrifugal force, the threshold condition at the different steering speed, steering radius, and the different road conditions are derived based on the rapid steering automobile’s stress analyzes. In this paper, the maximum allowable speed of automobile rapid steering without occurring side slip and side tumbling is present. It provides a theory foundation for studying safety and the automobile rapid steering control.

The accurate prediction of crop yield is of great help for grain policy making as the importance of food in human life. By assuming a homogeneous and vertical laminar structure and introducing a multilayer-two-big-leaf model, we developed a radiative transfer equation for winter wheat canopy and a model named RS-P-YEC (Remote Sensing — Photosynthesis — Yield Estimation for Crop) for winter wheat yield estimation. In this model, we converted the net primary productivity to winter wheat yield using harvest index. In this study, we estimated yield of winter wheat in North China Plain using the RS-P-YEC model. The simulated yield agrees well with observations from agro-meteorological stations and the R2 reaches to 0.817. This study demonstrates that RS-P-YEC model is useful in the yield estimation of winter wheat in North China Plain with widely available remotely sensed images.

Based on snow depth data of Special Sensor Microwave Imager (SSM/I), snow cover data of NOAA/AVHRR, and snow depth and snow cover data of six weather stations over Northern Tibet Plateau (NTP), we studied snow cover distribution in temporal and spatial scales, and analyzed the influencing factors of snow in the NTP region. The results shown that, in the seasonal cycle, the snow over extent increased rapidly in autumn and winter seasons in the NTP regions over past 40 years. In interannual cycle, the snow cover variation indicated a reducing-increasing -reducing dynamic process in the study area from 1960 to 2003. The wavelet analyses shown that there were oscillation periods of quasi-2~3 yr, quasi-9 yr, quasi-13 yr for temporal distributions of annual cumulative snow cover. In spatial scale, the snow cover (exceeded 15 ten-days over each half-year) mainly occurred in the east part of the NTP region. The greatest variance of snow cover was found in middle and eastern part of the NTP, i.e., Andu and Nierong regions. The analysis of snow cover influencing factors revealed that the temperature and precipitation are the main factors.

We demonstrate a method to precisely calibrate the relative position between an optical dipole trap and a magnetic quadrupole potential in making a Bose-Einstein condensate via the hybrid trap. We measure the displacement by the dipole oscillation in the gravity direction, where the oscillation frequency can be adjusted through an additional bias magnetic field. One frequency corresponds to the case of the mode matching while two frequencies are not, and the great consistency between theoretical simulation and experimental results indicates its usefulness.

To investigate the characteristics of dynamic color processing, we adopted two patterns of visual stimulus that were "onset-offset" which reflected static color stimulus and "sustained moving" without abrupt mode which reflected dynamic color stimulus to evoke event-related brain potentials (ERPs) of both normal and abnormal subjects. ERPs were recorded by neuroscan system and analyzed to uncover the follow results. In normal group, ERPs in response to dynamic red stimulus were characterized by frontal positive amplitudes with a latency of about 180 ms and the peak latency of the late positive potential (LPP) in a time window between 290 and 580 ms. In abnormal group and singularly individual of normal group, ERPs in response to dynamic red stimulus were fully lost and characterized by vanished amplitudes between 0 and 800 ms. ERPs of two groups in response to dynamic green and blue stimulus were the same as ERPs of the normal group in response to red stimulus. In comparison with, ERPs of the two groups in response to static red, green and blue stimulus were not different, which were only characterized by a peak latency of LPP in a time window between 350 and 650 ms. Our results firstly pointed to the view that a novel phenomena that the above some subjects could not completely apperceive a sort of dynamic red stimulus by ERPs was observed and called "dynamic red blindness". Furthermore, our results also suggested that low-frequency ERPs induced by "sustained moving" maybe a good and new method for testing dynamic color perception competence.

By using the Hamiltonian included in the static Su-Schrieffer-Heeger model and the Coulomb potential of solitons and ions, we investigated the insulator-metal transition mechanism in Na-doped trans-polyacetylene and gave the dependence of the Pauli susceptibility for 8.33% Na doping on the various widths and arrangements of the solitons.

We synthesize MAl12O19 (M = Ca, Sr, Ba) singly doped with Eu2+ or Cr3+ and co-doped with Eu2+ and Cr3+ by high-temperature solid-state reaction under reducing atmosphere. It is observed that there exit energy transfers from Eu2+ to Cr3+ in MAl12O19 (M = Ca, Sr, Ba) hosts. Although the MAl12O19 (M= Ca, Sr, Ba) hosts have similar crystal structures, the energy transfer efficienies and the conversion rates of the blue light to the red light are different. Both experiment and calculation show that the energy transfer from Eu to Cr in CaAl12O19 host is most efficient, and the ratio of the red emission to the blue emission in CaAl12O19 host is the highest among the three different hosts.

The spectral properties of nanoparticles Gd2O3:Eu3+ have been investigated by using Judd Ofelt theory at 77K. Intensity parameters Ωλ(λ＝2，4) were calculated using the experimental data of 5D0→7F2 and 5D0→7F4 transitions by taking the magnetic dipole transition 5D0→7F1 as reference. The intensity of the transition is almost completely unaffected by the local environment. It is indicated that intensity parameter Ωλ changes with the variation of diameter of nanoparticles Gd2O3:Eu3+,dramatically different from that of the bulk material.With decreasing diameter of the nanoparticles Gd2O3:Eu3+ from 135 to 15nm,the quantum efficiency of the emitting level 5D0 reduces from 23.6% to 4.6%. The smaller the diameter of nanoparticles Gd2O3:Eu3+, the bigger the ratio of surface to volume and the more the surface defect.It is the enhancing of the non radiation channels that results in the decrease of the quantum efficiency. The other two non radiation channels, charge (Eu3+-O2-) transfer state and multiphonon nonradiative re excitaton, were also studied.

The exchange interaction is considered to play the dominant role in the quenching of 5D0—7F2 emission of Eu3+ in Y2O3 nanocrystals.Luminescence decay curves of 5D0-7F2 of Eu3+ in two sizes of nanocrystals were measured.We fit the luminescence decay curve by the Inokuti-Hirayama theory.The efficiencies of energy transfer of exchange interaction were calculated.The difference between theoretical and experimental curves of efficiency was analyzed.

In this paper, a new mechanism of anti-Stokes fluorescent cooling based on the energy transfer among the centers within the inhomogeneously broadened line is proposed. The dependence of relative cooling efficiency on excitation photon energy and temperature is discussed.

By measuring the excitation spectra of the 4f5d bands and the fluorescent decays of the 5D J 7F 0 (J =2,1,0) transition probability depending on temperature in M yM ′ 1-y F Cl x Br 1-x :Sm 2+ ( M =Mg, Ca, Sr, Ba)series, we have studied the dependence of the energy separation between the 4f5d bands and the 5D J level, the 5D J 7F 0(J=2,1,0 ) transition probability on the composition grade ( x ) and ( y ) and the effect on hole burning efficiency. We draw conclusions as below: In M yM ′ 1-y FCl x Br 1-x :Sm 2+ series, the 4f5d bands will be more close to the 5D J level with the increase of the Br concentration and the concentration of small radium alkaline earth ion, and this situation makes the 5D J 7F 0 electron transition probability increase. By reasoning, the hole burning efficiency of Sm 2+ are expected to be enhanced.