Removal of heavy metals from kaolin using an upward electrokinetic soil remedial (UESR) technology

An upward electrokinetic soil remedial (UESR) technology was proposed to remove heavy metals from contaminated kaolin. Unlike conventional electrokinetic treatment that uses boreholes or trenches for horizontal migration of heavy metals, the UESR technology, applying vertical non-uniform electric fields, caused upward transportation of heavy metals to the top surface of the treated soil. The effects of current density, treatment duration, cell diameter, and different cathode chamber influent (distilled water or 0.01 M nitric acid) were studied. The removal efficiencies of heavy metals positively correlated to current density and treatment duration. Higher heavy metals removal efficiency was observed for the reactor cell with smaller diameter. A substantial amount of heavy metals was accumulated in the nearest to cathode 2 cm layer of kaolin when distilled water was continuously supplied to the cathode chamber. Heavy metals accumulated in this layer of kaolin can be easily excavated and disposed off. The main part of the removed heavy metals was dissolved in cathode chamber influent and moved away with cathode chamber effluent when 0.01 M nitric acid was used, instead of distilled water. Energy saving treatment by UESR technology with highest metal removal efficiencies was provided by two regimes: (1) by application of 0.01 M nitric acid as cathode chamber influent, cell diameter of 100 mm, duration of 18 days, and constant voltage of 3.5 V (19.7 k Wh/m(3) of kaolin) and (2) by application of 0.01 M nitric acid as cathode chamber influent, cell diameter of 100 cm, duration of 6 days, and constant current density of 0.191 mA/cm(2) (19.1 k Wh/m(3) of kaolin).     

Quantum dot encapsulation in viral capsids

Incorporation of CdSe/ZnS semiconductor quantum dots (QDs) into viral particles provides a new paradigm for the design of intracellular microscopic probes and vectors. Several strategies for the incorporation of QDs into viral capsids were explored; those functionalized with poly(ethylene glycol) (PEG) can be self-assembled into viral particles with minimal release of photoreaction products and enhanced stability against prolonged irradiation.     

Comparison of airflow and particulate matter transport in multi-room buildings for different natural ventilation patterns

This study numerically investigates airflow characteristics and particulate matter (PM) transport in multi-room buildings for different natural ventilation patterns with the same air change rate. Four typical natural ventilation patterns (full-open, pass-through, right short-circuit and left short-circuit), representing the ratios of the outlet-to-inlet opening size ranging from 1.67 to 0.17, are considered to study multi-room airflow characteristics. A measured indoor PM₁₀ profile in Taipei Metropolis is input into the above four ventilation patterns as the initial condition of the PM size distribution. The time variation of indoor PM₁₀/PM_2.5/PM₁ concentrations in each room for various ventilation patterns is next investigated. The effect of ventilation pattern on particle removal mechanism is emphasized. The results show that although the air change rate of the building is the same, airflow characteristics and PM transport behaviors are quite different for various ventilation patterns. The removal efficiencies of PM₁₀ for the four ventilation patterns are all found to be much better than those of PM_2.5 and PM₁. Particle escape is the major mechanism to remove PM for rooms with double-sided ventilation, whereas particle deposition is important for single-sided ventilation rooms.     

High dielectric constant terbium oxide (Tb2O3) dielectric deposited on strained-Si:C

High-k Tb₂O₃ films deposited on strained-Si:C and treated with different post-rapid thermal annealing temperatures were formed as alternative gate dielectrics in metal oxide semiconductor devices. The dielectrics were investigated by X-ray diffraction, X-ray photoelectron spectroscopy, atomic force microscopy, and electrical measurements. It was found that Tb₂O₃ dielectrics properly annealed at 800 °C form well-crystallized Tb₂O₃ structures with few defects.     

The characteristics of transparent conducting Al-doped zinc oxide thin films deposited on polymer substrates

Al-doped zinc oxide (AZO) transparent, conductive thin films were deposited on inexpensive polyethylene terephthalate substrates, using radio frequency (rf) magnetron sputtering, with an AZO ceramic target (the Al₂O₃ content is approximately 2 wt%). This paper presents an effective method for the optimization of the parameters for the deposition process for AZO thin films with multiple performance characteristics, using the Taguchi method, combined with grey relational analysis. Using the Taguchi quality design concept, an L₉ orthogonal array was chosen for the experiments. The effects of various process parameters (rf power, substrate-to-target distance, substrate temperature and deposition time) on the electrical, structural, morphological and optical properties of AZO films were investigated. In the confirmation runs, using grey relational analysis, the electrical resistivity of the AZO films was found to have decreased from 5.0?×?10^?3 to 1.6?×?10^?3?Ω-cm and the optical transmittance was found to have increased from 74.39 to 79.40%. The results demonstrate that the Taguchi method combined with grey relational analysis is an economical way to obtain the multiple performance characteristics of AZO films with the fewest experimental data. Additionally, by applying an Al buffer layer, of thickness 10?nm, the results show that the electrical resistivity was 3.1?×?10^?4?Ω-cm and the average optical transmittance, in the visible part of the spectrum, was approximately 79.12%.     

流态化炉内物料停留时间分布的数学模型

在分析流化床内的气固流动特性和各种流化床的流体动力学数学模型的基础上,建立KLDH数学模型,以此可计算流态化炉内密相段与悬浮段的物料停留时间分布。结合流态化炉的实际操作参数,计算炉内物料的停留时间。     

Seamless Streaming Media for Heterogeneous Mobile Networks

As the mobile networking technologies evolve, people are able to access the Internet through heterogeneous wireless access networks, such as WLAN, GPRS, 3G and Beyond 3G networks. For the coverage, bandwidth and cost of these heterogeneous mobile access networks are quite different, a mobile host may hand over among them, and this is called vertical handoffs. One of the most important issues for heterogeneous mobile networks is that vertical handoffs may degrade the quality of the time-sensitive streaming media services, even interrupt them. To overcome the problem, in the paper a multicast-based redundant streaming architecture is proposed. The proposed architecture is implemented in the all-IPv6 heterogeneous mobile networks. Five experiments are performed to evaluate the performance of the proposed architecture. The experimental results and the analysis show that the proposed architecture is capable of providing seamless streaming services even if the vertical handoffs or the traffic congestion occurs. Moreover, it is found that the traffic overhead is only 1.0368% per vertical handoff for each mobile access network, and thus the feasibility of the proposed architecture is demonstrated.

Low-power fully integrated and tunable CMOS RF wireless receiver for ISM band consumer applications

A 0.25-/spl mu/m single-chip CMOS single-conversion tunable low intermediate frequency (IF) receiver operated in the 902-928-MHz industrial, scientific, and medical band is proposed. A new 10.7-MHz IF section that contains a limiting amplifier and a frequency modulated/frequency-shift-key demodulator is designed. The frequency to voltage conversion gain of the demodulator is 15 mV/kHz and the dynamic range of the limiting amplifier is around 80 dB. The sensitivity of the IF section including the demodulator and limiting amplifier is -72 dBm. With on-chip tunable components in the low-power low-noise amplifier (LNA) and LC-tank voltage-controlled oscillator circuit, the receiver measures an RF gain of 15 dB at 915 MHz, a sensitivity of -80 dBm at 0.1% bit-error rate, an input referred third-order intercept point of -9 dBm, and a noise figure of 5 dB with a current consumption of 33 mA and a 2450 /spl mu/m/spl times/ 2450 /spl mu/m chip area.     

The Effects of Drain-Bias on the Threshold Voltage Instability in Organic TFTs

In this letter, the influence of drain bias on the threshold voltage instability in pentacene-based organic thin-film transistors (OTFTs) was studied. By applying different drain biases to adjust the channel carrier concentration in linear mode, the threshold voltage shift was found to be proportional to the carrier concentration. The experimental data can be well quantitatively explained by the drain bias-stress theory developed for a-Si TFTs. The outcome gives the insight of the degradation mechanism of OTFTs and is important for the design of OTFT pixel circuit, OTFT analog amplifiers, or OTFT active loads.