纳米光触媒降解低浓度氨气效能检测方法开发

开发了一种低成本快速创新的检测方法,主要装置为紫外线/可见光分光光度计及石英比色槽,较以往使用气相层析/质谱仪、傅立叶转换红外线光谱仪检测光触媒材料对气体降解效能简单又快速.实验时先将特定浓度气体注入一个密闭的石英比色槽中,再将比色槽置入紫外线/可见光分光光度计内进行检测,以获得特定浓度气体吸收光谱图及制备检量线,氨气检量线浓度范围为1×10-6～4×10-5.在光触媒材料进行异相光催化降解氨气效能分析检测时,将两种TiO2纳米触媒材料定量在石英基板上,置入比色槽内并注入氨气.同时将比色槽用UV光照射,进行降解实验,随后再将比色槽用紫外线/可见光分光光谱仪进行测试,由吸收光谱图中吸收强度,比对检量线,获得气体浓度变化以及光触媒材料对气体的降解效率.实验结果显示,真空潜弧合成系统自制的SANSS-TiO2光触媒,可将氨气的浓度降至原有的10.18%,商用纳米TiO2,仅能降至原有的49.7%.本研究已成功的建立简单,快速可靠的解低浓度氨气效能检测技术.     

Iron oxide-impregnated filter paper (Pi test): II. A review of its application

The iron oxide impregnated filter paper test (P_i test) is a recently developed soil test for phosphorus (P) in which the FeO paper acts as an infinite sink for P mobilized in a soil solution. Several papers have been published evaluating the effectiveness of the test for predicting plant availability of P under different soil conditions. The use of FeO paper to predict algal availability of P in water bodies and runoffs has also been studied.The purpose of this paper is to review studies on the use of the P_i test to evaluate plant availability of P in soils, and predict availability of P to algae in an aquatic environment. Phosphorus extracted by the FeO paper is primarily physically bound extractable (resin P) and correlates significantly with Bray I and Mehlich P in acid soils and Olsen P in calcareous soils. Dry-matter yield and P uptake by maize (Zea mays L), kidney beans (Phaseolus vulgaris L), and upland rice (Oryza sativa L) grown in acidic soils correlated well with P_i-P. Likewise, in calcareous soils, P_i-P was as good as Olsen-P in predicting crop response. Field trials have shown that the P_i test is a good predictor of plant yield in soils with wide ranging properties. Compared to the standard method to measure bioavailable P to algae in waters and agricultural runoffs involving lengthy algal essays culturing selenastrum capricornutum with sediment samples, the P_i method is a faster and easier method to estimate P that may be potentially available for uptake by algae.     

Soil testing for available phosphorus in soils where phosphate rock-based fertilizers are used

Traditional soil tests for phosphorus (P) were developed to arrive at fertilizer recommendations when water-soluble P fertilizers have been used. When slowly water-soluble fertilizers such as phosphate rock (PR) have been used, soil tests using acidic extractants overestimate bioavailability of P, whereas alkaline extractants underestimate it. Therefore, separate calibration curves are needed for soluble and PR-based fertilizers. There are two soil tests that show promise as suitable tests in soils fertilized with soluble as well as PR-based fertilizers. These are the iron oxide impregnated paper (P _i ) test and the ion exchange resin paper test. In both cases, the strips act as a sink for P mobilized in a soil solution, and P measured depends only on the concentration of P mobilized in the solution and not on the source of P or properties of the soil. Both tests somewhat simulate the sorption of P by plant roots without disturbing the chemical equilibrium, unlike other tests that extract P by the destructive dissolution of specific soil P compounds. In both cases, P measured from soils fertilized with PR-based fertilizers has shown very good correlation with plant response. Field calibration with crops under different pedological and agroecological regimes is needed for using these soil tests in developing fertilizer recommendations.     

MIMO‐UWB smart antenna communication characteristics for different antenna arrays of transmitters

The channel capacity of indoor multiple‐input multiple‐output ultra‐wide band (MIMO‐UWB) transmission for smart antenna is presented. The genetic algorithm (GA) is used to synthesize the radiation pattern of the directional antenna array to maximize the capacity performance in indoor MIMO‐UWB communication system. Three types of antenna arrays such as circular shape, L shape and Y shape arrays are used in the transmitter and their corresponding capacity on several paths in the indoor environment are calculated. The UWB impulse responses of the indoor channel for any transmitter‐receiver location are computed by applying shooting and bouncing ray/image (SBR/image) techniques, inverse fast Fourier transform and Hermitian processing. By using the calculated frequency response, the capacity performance of the synthesized antenna pattern on MIMO‐UWB system can be computed. Based on the topography of the antenna array and the capacity formula, the array pattern synthesis problem can be reformulated into an optimization problem and solved by the GA algorithm. The GA algorithm optimization is applied to a high order nonlinear optimization problem. The novelties of our approach is not only choosing capacity as the cost function instead of sidelobe level of the antenna pattern, but also considering the antenna feed length effect of each array element. The cost function for the problem is nonsmooth and discontinuous with respect to the antenna pattern. It is difficult to solve by gradient methods, since the derivative is hard to derive. The GA algorithm is employed to optimize the excitation voltages and feed lengths for these antenna arrays to increase the capacity. The strong point of the GA is that it can find out the solution even if the performance index cannot be formulated by simple equations. Numerical results show that the synthesized antenna array pattern is effective to focus maximum gain to the LOS path for these antenna arrays. In other words, the receiver can increase the received signal energy to noise ratio. The synthesized array pattern also can mitigate severe multipath fading in complex propagation environment. As a result, the capacity can be increased substantially in indoor MIMO‐UWB communication system. The investigated results can help communication engineers improve their planning and design of indoor wireless communication. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.     

A spectral collocation method for a rotating Bose–Einstein condensation in optical lattices

We extend the study of spectral collocation methods (SCM) in Li et al. (2009) [1] for semilinear elliptic eigenvalue problems to that for a rotating Bose–Einstein condensation (BEC) and a rotating BEC in optical lattices. We apply the Lagrange interpolants using the Legendre–Gauss–Lobatto points to derive error bounds for the SCM. The optimal error bounds are derived for both H¹-norm and L²-norm. Extensive numerical experiments on a rotating Bose–Einstein condensation and a rotating BEC in optical lattices are reported. Our numerical results show that the convergence rate of the SCM is exponential, and is independent of the collocation points we choose.     

Note: Development of a high resolution six-degrees-of-freedom optical vibrometer for precision stage

A high resolution six degrees of freedom (6-DOF) optical vibrometer is proposed. 6-DOF vibrations can be simultaneously measured using the proposed optical vibrometer, which reduces measurement time and number. The performance of the proposed vibrometer is verified by experiments. The results show that the accuracy of the proposed optical vibrometer is ±30 nm∕200 nm and ±0.04 arcsec∕0.1 arcsec at 1000 Hz.     

Effects of molecular weight on electroluminescence of nanogold‐bonded poly(9,9‐dioctylfluorene‐alt‐thiophene) at a constant polymer‐to‐gold weight ratio

The effects of molecular weight on electroluminescent properties of the light emitting polymeric nanocomposite, poly(9,9‐dioctylfluorene‐alt‐thiophene) with chemically bonded gold nanoparticles (PDOFT‐Au), have been studied under a condition of constant polymer‐to‐gold weight ratio. The polymer, PDOFT, was first synthesized via the Suzuki cross‐coupling reaction and then bonded to in situ‐formed gold nanoparticles (AuNPs) via terminal thiol functional groups which had been generated during the quenching of polymerization. A series of PDOFT‐Au's of various molecular weights have thus been synthesized. At a constant polymer‐to‐gold weight ratio, the average size of gold nanoparticles (AuNPs) increased with an increase in the molecular weight of PDOFT. Although an increased molecular weight led to a red shift in UV‐absorption and PL spectra as well as an increased PL quantum efficiencies (?_PL) for all samples (both PDOFT and PDOFT‐Au), the effect of AuNPs bonding became more noticeable when the molecular weight was higher. As for light emitting diode (LED) device fabrication, an increase in the molecular weight of PDOFT also led to a red shift in the EL spectra of the fabricated LED devices. Nevertheless, PDOFT‐Au, compared with PDOFT, had a lower threshold voltage, an increased brightness and current density, and an improved photometric efficiency. Moreover, the photometric efficiency increased with an increase in the molecular weight of the polymer, from 0.298 cd/A for PDOFT‐Au3 up to 0.645 cd/A for PDOFT‐Au1. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Fun and Accurate Static Balance Training to Enhance Fall Prevention Ability of Aged Adults: A Preliminary Study

Fall prevention is critical for aged adults as falling down has been cited as the number one cause of accidental death in aged adults. Static balance training is an effective method of increasing the balancing capacity in aged adults and reducing their fall risk. This article discusses a method that combines virtual reality (VR) technology with motion‐capture devices for aged adults to practice static balance training in a fun and accurate environment. The aged adults wore motion‐capture devices to interactively manipulate a three‐dimensional (3D) human model (HM) in a virtual environment to follow a 3D posture model (PM). The proposed method was implemented using commercial, off‐the‐shelf 3D tools. A preliminary usability study was conducted, and the results show that the parameters of PM design will affect the aged adult's posture control performance. Our method has several advantages over the currently existing approaches. First, by adjusting the PM parameters, different posture control programs could be designed to support customized static balance training. Second, collision detections between the HM and PM could be used to accurately monitor the posture control process and to interactively provide feedback to the trainee. Third, posture control quality could be quantitatively evaluated by analyzing the collision data between the HM and PM. The proposed method could be used to develop a fun, accurate, and customized static balancing capacity training environment for aged adults. © 2012 Wiley Periodicals, Inc.