Biofiltration and inhibitory interactions of gaseous benzene, toluene, xylene, and methyl tert-butyl ether

This study evaluated the individual and combined removal capacities of benzene, toluene, and xylene (B, T, and X) in the presence and absence of methyl tert-butyl ether (MTBE) in a polyurethane biofilter inoculated with a BTX-degrading microbial consortium, and further examined their interactive effects in various mixtures. In addition, Polymerase chain reaction-denaturing gradient gel electrophoresis and phylogenetic analysis of 16S rRNA gene sequences were used to compare the microbial community structures found in biofilters exposed to the various gases and gas mixtures. The maximum individual elimination capacities (MECs) of B, T, and X were 200, 238, and 400 g m(-3) h(-1), respectively. There was no significant elimination of MTBE alone. Addition of MTBE decreased the MECs of B,T, and X to 75, 100, and 300 g m(-3) h(-1), respectively, indicating that benzene was most strongly inhibited by MTBE. When the three gases were mixed (B + T + X), the removal capacities of individual B, T, and X were 50, 90, and 200 g m(-3) h(-1), respectively. These capacities decreased to 40, 50, and 100 g m(-3) h(-1) when MTBE was added to the mix. The MEC of the three-gas mixture (B + T + X) was 340 g m(-3) h(-1), and that of the four-gas mixture was 200 g m(-3) h(-1). Although MTBE alone was not degraded by the biofilter, it could be co-metabolically degraded in the presence of toluene, benzene, or xylene with the MECs of 34, 23, and 14 g m(-3) h(-1), respectively. The microbial community structure analysis revealed that two large groups could be distinguished based on the presence or absence of MTBE, and many of the dominant bacteria in the consortia were closely related to bacteria isolated from aromatic hydrocarbon-contaminated sites and/ or oil wastewaters. These findings provide important new insights into biofiltration and may be used to improve the rational design of biofilters for remediation of petroleum gas-contaminated airstreams according to composition types of mixed gases.     

Error analysis of a parallel mechanism considering link stiffness and joint clearances

In order to utilize a parallel mechanism as a machine tool component, it is important to estimate the errors of its end-effector due to the uncertainties in parts. This study proposes an error analysis for a new parallel device, a cubic parallel mechanism. For the parallel device, we consider two kinds of errors. One is a static error due to link stiffness and the other is a dynamic error due to clearances in the parts. In this study, we propose a stiffness model for the cubic parallel mechanism under the assumption that the link stiffness is a linear function of the link length. Also, from the fact that the errors of u-joints and spherical joints are changed with the direction of force acting on the link, they are regarded as a part of link errors, and then the error model is derived using forward kinematics. Lastly, both the error models are integrated into the total error, which is analyzed with a test example that the platform moves along a circular path. This analysis can be used in predicting the accuracy of other parallel devices.     

A 12-bit 10-MS/s SAR ADC with a weighted sampling time technique applied to C-DAC

This paper presents a low power 12-bit 10-MS/s successive approximation register (SAR) analog-to-digital convert (ADC) for bio-signal signal processing in wearable sensor systems. A weighted sampling time technique applied to a capacitor digital to analog converter (C-DAC) is employed to reduce the power consumption of the conventional SAR ADC with minimum performance sacrifice. The proposed technique helped reduce its energy consumed by MSB, MSB-1, MSB-6, and MSB-7 capacitors by more than 40% compared with that of the conventional C-DAC. Another technique, a voltage scaling method is also employed to lower the power supply voltage from 1.2 to 0.6 V for all the digital logics except the output registers, such that it results in a power reduction of 70%. The proposed ADC is implemented with the standard CMOS 65 nm 1-poly 6-metal n-well process. The ADC achieves DNL/INL of?±?1.2LSB/?±?1.5LSB, ENOB of 10.3-b, power consumption of 31.2 μW, and Walden FoM of 2.7fJ/step.

     

The Impact of LTE UE on Audio Devices

In this letter, the acoustic noise due to long term evolution (LTE) user equipment (UE) is investigated with various transmitting powers of the LTE UE by using the Monte Carlo method in a practical acoustic noise experiment.     

An optical surveillance technique based on cavity mode analysis of SL-RSOA for GPON

An optical in-service surveillance technique based on cavity mode analysis of self-injection locked reflective semiconductor optical amplifier (SL-RSOA) for gigabit-capable passive optical network (GPON) is proposed. At each optical network unit (ONU), an upstream transmitter utilizing SL-RSOA can generate both upstream data signal and surveillance signal due to presence of external cavity. We can able to detect both upstream data and surveillance signals from all ONUs simultaneously at the optical line terminal (OLT) by assigning a distinct cavity mode frequency to each upstream transmitter. We also estimate the power penalty induced by the surveillance signals on the upstream data channel during simultaneous detection mechanism. Further, we propose an alternative method to detect the surveillance signals by allocating a separate monitoring time slot in upstream GPON transmission convergence (GTC) frame so as to reduce the influence of surveillance signals on the upstream data channel.     

An asymptotic solution of EM backscattering from a conducting sphere coated with a composite material

An asymptotic high frequency solution for the electromagnetic (EM) backscattered field produced by a plane wave incident on a perfectly conducting sphere coated with a thin composite material is derived in this paper. For the formulation of the incident and the reflected field the characteristics of the wave transformation and the line integral via the stationary phase method were applied, respectively, and the obtained results are cast in the ordinary ray formats of a geometrical optics field. Based on the Watson transform technique, the diffracted field is also formulated from the residue series solution of the problem and presented in a form suitable for the numerical calculation. The numerical results obtained from the derived asymptotic solution show excellent agreement with those from the rigorous eigenfunction solution.     

Improved Electrical Contact Properties of MoS2‐Graphene Lateral Heterostructure

2D materials have been extensively investigated in view of their excellent electrical/optical properties, with particular attention directed at the fabrication of vertical or lateral heterostructures. Although such heterostructures exhibit unexpected or enhanced properties compared to those of singly used 2D materials, their fabrication is challenged by the difficulty of realizing spatial control and large area integration. Herein, MoS₂ is grown on patterned graphene at variable temperatures, combining the concept of lateral heterostructure with chemical vapor deposition to realize large area growth with precise spatial control, and probe the spatial distribution of graphene and MoS₂ by a number of instrumental techniques. The prepared MoS₂‐graphene lateral heterostructure is employed to construct field effect transistors with graphene as the source/drain and MoS₂ as the channel, and the performance of these transistors (on/off ratio ≈10⁹, maximum field effect mobility = 8.5 cm² V^?1 s^?1) is shown to exceed that of their MoS₂‐only counterparts.     

Spectrally efficient modulation and spreading scheme for CDMAsystems

A novel modulation and spreading scheme is proposed based on the orthogonal complex rotator that outperforms the traditional PN (pseudo noise) complex QPSK method in terms of adjacent channel power. This scheme is important for hand-held terminals because it increases battery life and capacity due to reduced interference. A mathematical analysis and adjacent channel power simulation results are provided and discussed     

Dealloyed AuNi Dendrite Anchored on a Functionalized Conducting Polymer for Improved Catalytic Oxygen Reduction and Hydrogen Peroxide Sensing in Living Cells

Dealloyed‐AuNi dendrite anchored on carboxylic acid groups of a conducting polymer is prepared and demonstrated for the catalysis of the oxygen reduction reaction (ORR) and detection of hydrogen peroxide (H₂O₂) released from living cells. The dendrite formation is initiated on a poly(benzoic acid‐2,2′:5′,2′′‐terthiophene) (pTBA) layer, where the polymer layer acts as a stable substrate to improve the long‐term stability and catalytic activity of the alloy electrode. A co‐deposition of Au and Ni is performed to produce a Ni‐rich Au surface at first; subsequent removal of the surface Ni atoms through electrochemical dealloying enhances the performance of the catalyst because of an increase in the electrochemically active area by 12 times. The hydrodynamic voltammetry of dealloyed‐AuNi@pTBA shows a half‐wave potential at –0.08 V, which is a large shift towards more positive potential when compared to those on AuNi@pTBA (?0.14 V) and commercial Pt/C (–0.12 V) electrodes. The proposed catalytic electrode achieved a superior analytical performance for the detection of trace H₂O₂ (at –0.15 V) released from cancer and normal cells with a very low detection limit (ca. 5 nM). In addition, the in vitro studies suggest no significant cytotoxicity effect for the dealloyed sample and the viability of the cells are more than 85% even after 48 h of incubation.