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Developing highly crystalline, single-phase and copper-poor Cu2ZnSnSe4 nanoparticles for solar cell application
摘要： In this study, we report the synthesis of Cu(Zn,Sn)Se2 (CZTSe) nanoparticles by hot-injection method for application to the absorber layer in solar cells. The composition of elements in the CZTSe nanoparticles depends mainly on the injection speed of the Se precursor. By controlling the injection speed, we obtained complete single-phase CZTSe nanoparticles with high crystallinity and copper-poor composition. The nanoparticle diameter mainly ranged from ~ 7 nm to 18 nm. The obtained CZTSe nanoparticles were used to fabricate a light absorber layer in the CZTSe solar cells. The cell exhibited performance, with short-circuit current density of ~ 30.8 mA/cm2, open-circuit voltage of 0.39 V, ?ll factor of 0.47 and conversion ef?ciency of 5.8%.
关键词： Hot-injection method,Single phase,CZTSe nanoparticles,Copper-poor composition
更新于2025-09-23 15:19:57
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a??Blind timea?? a?? current limitations on laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) for ultra-transient signal isotope ratio analysis and application to individual sub-micron sized uranium particles
摘要： The application of laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) to the isotope ratio analysis of UOx particles has the potential to improve the isotopic determination of these particles when compared to currently utilised ICP-MS techniques. To investigate this a high-speed, integrated ablation cell and dual concentric injector design, was tested in the expectation that the resulting increase in signal to noise ratio and sample ion yield would improve the determination of 234U/238U, 235U/238U and 236U/238U for such materials. However, when compared to a slower washout, more established low-volume cell design, the highly transient signals of the new design proved challenging for the mixed detector array of the multi-collector mass spectrometer, introducing a new bias. We describe a major component of this bias, referred to as ‘blind time’, and model its impact on UOx particle analysis. After accounting for blind time, average precisions for the uranium isotopic composition of sub-micron sized UOx particles using LA-MC-ICP-MS were 3 % 1RSD for 235U/238U and 8 % 1RSD for 234U/238U. When ablating a glass rather than a UOx particle, uncertainties of 1.3 % 1RSD for 235U/238U were achieved for 150 nm equivalent particle sizes using LA-MC-ICP-MS.
关键词： isotope ratio analysis,UOx particles,uranium isotopic composition,LA-MC-ICP-MS,blind time
更新于2025-09-23 15:19:57
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Measurement and Analysis of Calcium Content in Wild Chinese Dwarf Cherry (<em>Prunus humilis</em>) Fruits by Inductively Coupled Plasma-optical Emission Spectrometer
摘要： Different forms of calcium in wild Chinese dwarf cherry (Prunus humilis) fruits (two genotypes, small-fruit-type and big-fruit-type) were sequential extracted and measured by Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES). The calcium content variation after postharvest storage was also studied, to provide the theory basis for the active nutritional ingredient evaluation of Chinese dwarf cherry (Prunus humilis). The results showed that, wild Chinese dwarf cherry (Prunus humilis) fruits in mature stage were rich in calcium nutrition element and mainly composed by water soluble calcium and calcium phosphate which absorbable to human. Absorbable calcium (including water soluble calcium and calcium phosphate) content in small-fruit-type (63.79%) was significantly higher than that of big-fruit-type (54.97%). After postharvest storage, the water soluble calcium content was increased while the calcium pectate and calcium oxalate content dropped. Especially to the big-fruit-type, the absorbable calcium content increased to 75.49% compared with just picking 54.97% (small-fruit-type increased from 63.79% to 68.86%). The study suggested that Chinese dwarf cherry (Prunus humilis) was a natural and biological calcium supplement to people; meanwhile, small-fruit-type was more suitable, especially after postharvest storage.
关键词： ICP-OES,calcium content,fruit,Calcium composition,chinese dwarf cherry (Prunus humilis)
更新于2025-09-23 15:19:57
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A Tightly Coupled VLC-Inertial Localization System by EKF
摘要： Spurred by Web technologies and service computing paradigm, more and more Web services have been delivered via standardized interfaces on the Internet. Mashup is exactly an enabling technology for end-users to combine these services into applications. However, there are some issues of end-user service development with mashup techniques. It not only requires users that develop application logics equipped with more or less programming skills, but also lacks a lightweight mashup model and systematic development approach in the existing mashup tools. To address these issues, we propose a data-driven service creation approach to facilitate application development and deployment. In the approach, we propose the service data model (SDM) for adaptation of heterogeneous Web services, the service relation model (SRM) for representation and re?nement of data interaction between services, and the service process graph (SPG) for describing business logics of mashup applications. We develop an IFrame implementation for SDM that can facilitate service providers to wrap heterogeneous Web services in a uni?ed way and display a visual element for the service. Meanwhile, we implement a pipeline as an intuitive form of SRM that can be used by end-users to develop business logic more effectively. To adapt the dynamic application scenarios, we also construct an event-driven execution mechanism for SPG. A lightweight service creation environment is then implemented to support end-users to develop applications in a simulative way, and a corresponding development methodology is introduced for this tool. Finally, the end-user evaluation and performance evaluation are conducted to evaluate our platform.
关键词： service composition,dataflow,Lightweight service creation,mashup,end-user development
更新于2025-09-23 15:19:57
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Effects of variation in background mixing ratios of N<sub>2</sub>, O<sub>2</sub>, and Ar on the measurement of <i>δ</i><sup>18</sup>O–H<sub>2</sub>O and <i>δ</i><sup>2</sup>H–H<sub>2</sub>O values by cavity ring-down spectroscopy
摘要： Cavity ring-down spectrometers have generally been designed to operate under conditions in which the background gas has a constant composition. However, there are a number of observational and experimental situations of interest in which the background gas has a variable composition. In this study, we examine the effect of background gas composition on a cavity ring-down spectrometer that measures δ18O–H2O and δ2H–H2O values based on the amplitude of water isotopologue absorption features around 7184 cm?1 (L2120-i, Picarro, Inc.). For background mixtures balanced with N2, the apparent δ18O values deviate from true values by ?0.50 ± 0.001 ‰ O2 %?1 and ?0.57 ± 0.001 ‰ Ar %?1, and apparent δ2H values deviate from true values by 0.26 ± 0.004 ‰ O2 %?1 and 0.42 ± 0.004 ‰ Ar %?1. The artifacts are the result of broadening, narrowing, and shifting of both the target absorption lines and strong neighboring lines. While the background-induced isotopic artifacts can largely be corrected with simple empirical or semi-mechanistic models, neither type of model is capable of completely correcting the isotopic artifacts to within the inherent instrument precision. The development of strategies for dynamically detecting and accommodating background variation in N2, O2, and/or Ar would facilitate the application of cavity ring-down spectrometers to a new class of observations and experiments.
关键词： background gas composition,correction models,Cavity ring-down spectroscopy,water isotopologues,isotopic artifacts
更新于2025-09-23 15:19:57
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Electrodynamic influence on the diurnal behaviour of neutral daytime airglow emissions
摘要： The diurnal variations in daytime airglow emission intensity measurements at three wavelengths OI 777.4 nm, OI 630.0 nm, and OI 557.7 nm made from a low-latitude location, Hyderabad (17.5? N, 78.4? E; 8.9? N MLAT) in India have been investigated. The intensity patterns showed both symmetric and asymmetric behaviour in their respective diurnal emission variability with respect to local noon. The asymmetric diurnal behaviour is not expected considering the photochemical nature of the production mechanisms. The reason for this observed asymmetric diurnal behaviour has been found to be predominantly the temporal variation in the equatorial electrodynamics. The plasma that is transported across latitudes due to the action of varying electric field strengths over the magnetic equator in the daytime contributes to the asymmetric diurnal behaviour in the neutral daytime airglow emissions. Independent magnetic and radio measurements support this finding. It is also noted that this asymmetric diurnal behaviour in the neutral emission intensities has a solar cycle dependence with a greater number of days during high solar activity period showing asymmetric diurnal behaviour compared to those during a low solar activity epoch. These intensity variations over a long timescale demonstrate that the daytime neutral optical emissions are extremely sensitive to the changes in the eastward electric field over low and equatorial latitudes.
关键词： Ionosphere (equatorial ionosphere–atmosphere interactions),Atmospheric composition and structure (airglow and aurora)
更新于2025-09-23 15:19:57
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Excellent electrostrictive coefficient in bismuth sodium titanate-based ceramics via regulating degree of diffuseness and phase composition
摘要： Herein, the strain (S) with low hysteresis can be achieved in [Bi0.5(Na0.72K0.18Li0.10)0.5]0.995Sr0.005(Ti0.995Ta0.005)O3-BaZrO3-NaNbO3 ceramics by an electrostrictive effect, and an excellent electrostrictive coefficient (Q33) of ～0.037 m4/C2 can be obtained under an electric field of 60 kV/cm. The enhancement of the degree of diffuseness regulated by phase compositions can effectively promote the electrostrictive response and increase the Q33 value. A higher ratio of P4bm and a larger Ps in P4bm guarantee the good linear relationship between S and P2 (P represents polarization), where a larger Ps (P4bm) can effectively restrict the expression of ferroelectric state with the increase of electric fields (E). Consequently, high Q33 values (0.033–0.037 m4/C2) are nearly independent of the applied electric fields. Although the strain from the electrostrictive effect is not tremendous, the good linear relationship between S and P2 is meaningful to the accurate displacement control in displacement actuators.
关键词： phase composition,degree of diffuseness,electrostrictive coefficient,bismuth sodium titanate-based ceramics
更新于2025-09-23 15:19:57
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Effects of TiO <sub/>2</sub> crystallinity and oxygen composition on forming characteristics in Pt/TiO <sub/>2</sub> /Pt resistive switching cells
摘要： “Forming” is a stage in resistive switching (RS) devices that occurs before switching and represents an important physical phenomenon in the universal operating mechanism of such devices. Forming in a resistance change material appears to be a kind of dielectric breakdown. In this study, we performed time-dependent forming (TDF) characterization of Pt/TiO2/Pt resistive switching cells with TiO2 layers of different crystallinities and oxygen compositions. We prepared two samples in which the grain boundary density and the density of oxygen vacancies differ, while both the TiO2 layers exhibited the similar crystal structures. Our results reveal that the Weibull slope and variation of time to forming are determined by the deposition method of the Pt bottom electrode (BE) ?lms. Moreover, the initial cell resistance and distribution of the TDF characteristics depend not only on the crystallinity but also on the oxygen composition of the TiO2 layers. The variation of time to forming increases as the distribution of initial resistance is reduced in Pt/NiO/Pt resistive switching cells with different NiO crystallinities. Conversely, the variation of time to forming decreases as the distribution of the initial resistance is reduced in the case of the Pt/TiO2/Pt cells. These results re?ect differences in both the grain boundary density (crystallinity) and the density of oxygen vacancies (oxygen composition) of resistance change materials used in the resistive switching cells. The clear difference of crystallinities and oxygen compositions might originate from differences in the oxide deposition mode during reactive sputtering.
关键词： oxygen composition,TiO2,forming,resistive switching,crystallinity
更新于2025-09-23 15:19:57
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Iron and the other metal species as phase-composition controllers the photocatalytic activity of TiO2 materials
摘要： The goal of the work is to verify which properties of TiO2-based materials, influenced by small amounts of Fe, Co, Ga, Bi, W, Mo, V and Ni species used as modifiers, play the predominant role in changing the photoactivity of TiO2. Two groups of materials were studied: TiO2 synthesized in the presence of nanocrystalline metal oxide and dissolved metal ions (cations or oxyanions). Sols were calcined at 450, 600 or 900°C. Physicochemical properties of the materials were characterized by XRD, DRS, SEM, EPR, porosimetry and photocurrent measurements. The most detailed studies were focused on modifications by iron species. TiO2 doping was achieved for both Fe3+ and Fe2O3 modifiers after calcination at temperatures equal to or higher than 450 and 900°C, respectively. Morphology of the materials (phase composition, specific surface area, etc.) were influenced by iron species even if they were not introduced into the crystal lattice of TiO2. Comparison of activity of photocatalysts and elucidation of the role of various reactive oxygen species were based on photooxidation tests involving Azure B and terephthalic acid. In general, iron species improved photocatalytic activity, nevertheless, doping of the materials appeared detrimental. A particular improvement of the activity was achieved for composites with low iron contents (ca. 0.01%mol Fe:Ti). The studies revealed, that beside the widely discussed mechanisms (photo-Fenton processes, charge separation, photosensitization, etc.) iron species can indirectly influence the photocatalytic activity of TiO2 acting as phase-composition controllers (PCC) during the synthesis of this oxide, which determine morphology of the resulting photocatalyst. To support this hypothesis, several sets of other TiO2 materials were modified with Co, Ga, Bi, W, Mo, V and Ni species. We show, that the use of these modifiers in small amounts can influence indirectly the activity of photocatalysts regardless to the type of modifier. Therefore different photoactivity of the tested materials should be attributed rather to these modifier-induced structural and electronic changes of the photocatalysts than to any other function of dopants, including photosensitization, enhanced charge separation, catalytic activity, at which most of studies are focused.
关键词： phase composition,photocatalysis,synthesis of photocatalysts,modified titanium dioxide
更新于2025-09-19 17:15:36
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MOPSS. I. Flat Optical Spectra for the Hot Jupiters WASP-4 b and WASP-52b
摘要： We present the first results from MOPSS, The Michigan Optical Planetary Spectra Survey, aimed at creating a database of optical planetary transmission spectra all observed, reduced, and analyzed with a uniform method for the benefit of enabling comparative exoplanet studies. We discuss our methods, and present results for our first two targets observed with the Magellan Baade 6.5 m telescope, one transit of the Hot Jupiter WASP-4b and two transits of the Hot Saturn WASP-52b. Both targets present flat, featureless spectra, corresponding to the presence of aerosols. We find that the cloud decks must begin no lower than 10?4 bar for both planets. For WASP-52b, we also consider the effects of star spots on the transmission spectrum, including unocculted spots and spots on the stellar limb influencing the light curve limb-darkening parameters. We discuss the usefulness of this program in the coming James Webb Space Telescope era.
关键词： planets and satellites: individual (WASP-52b, WASP-4b),planets and satellites: gaseous planets,planets and satellites: atmospheres,starspots,planets and satellites: composition
更新于2025-09-19 17:15:36