Back surface reflectors with periodic textures fabricated by self-ordering process for light trapping in thin-film microcrystalline silicon solar cells

Back surface reflectors (BSRs) with grating structures have been developed to enhance light trapping in thin-film hydrogenated microcrystalline Si (μc-Si:H) solar cells. As a grating structure, a periodic honeycomb-like dimple pattern with a period of ～450 nm has been fabricated on Al substrates by a self-ordering process using anodic oxidation of Al. The clear diffraction effect has been confirmed on the patterned Al from the angle-dependent reflection. From quantum efficiency measurements, we found that the periodically patterned BSR can confine the incident light more effectively than the random textured BSR, especially at longer wavelengths.     

Removal of selected pharmaceuticals by chlorination, coagulation-sedimentation and powdered activated carbon treatment

Removal property of nine pharmaceuticals (clofibric acid, diclofenac, fenoprofen, gemfibrozil, ibuprofen, indomethacin, ketoprofen, naproxen and propyphenazone) by chlorination, coagulation-sedimentation and powdered activated carbon treatment was examined by laboratory-scale experiments under the conditions close to actual drinking water treatment processes. Indomethacin and propyphenazone were completely degraded by chlorination within 30 minutes, but others remained around 30% (naproxen and diclofenac) or more than 80% of the initial concentration after 24 hours. A couple of unidentified peaks in a chromatogram of the chlorinated samples suggested the formation of unknown chlorination by-products. Competitive adsorption was observed when the mixed solution of the target pharmaceuticals was subjected to batch adsorption test with powdered activated carbon. Clofibric acid and ibuprofen, which were relatively less hydrophobic among the nine compounds, persisted around 60% of the initial concentration after 3 hours of contact time. Removal performance in actual drinking water treatment would become lower due to existence of other competitive substances in raw water (e.g. natural organic matter). Coagulation-sedimentation using polyaluminium chloride hardly removed most of the pharmaceuticals even under its optimal dose for turbidity removal. It is suggested that the most part of pharmaceuticals in raw water might persist in the course of conventional drinking water treatments.     

Fluorescence EXAFS analysis of ErP grown on InP by organometallic vapor phase epitaxy using a new organometal Er(EtCp)3

We have investigated local structures of ErP grown by organometallic vapor phase epitaxy Er source: tris(ethylcyclopentadienyl)erbium (Er(EtCp)₃ by extended X-ray absorption fine structure (EXAFS) measurement. The EXAFS analysis revealed that NaCl-type ErP and Er–O(–C) compounds coexisted in the case of ErP growth by using Er(EtCp)₃. The NaCl-type ErP was preferentially formed on InP(1 1 1)A compared with InP(0 0 1) and InP(1 1 1)B. It is considered that formation of unexpected Er–O(–C) compounds is due to low but significant concentration of residual O and/or C in Er(EtCp)₃.     

Calculation of magnetic near field generated by the contact discharge of an ESD gun

An ESD (electrostatic discharge) testing is specified in the IEC 61000‐4‐2, in which the detailed waveform of the discharge current injected by an ESD gun is prescribed. However, due to lack of understanding of the discharge process, it is difficult to confirm whether or not the IEC current waveform can be injected onto actual equipment. We thus previously proposed an equivalent circuit model for the ESD gun based on its geometrical structure, and showed decisive factors for the discharge current. In this study, in order to confirm the feasibility of the above equivalent circuit model, we measured with a 6‐GHz wide‐band digital oscilloscope the discharge current through an SMA connector and the resultant magnetic near field for the contact discharge of an ESD gun. As a result, we found that both measured waveforms approximately agree with those calculated from our equivalent circuit model. We then measured with respect to charge voltages the magnetic near fields for the contact discharge of the ESD gun to the ground, which revealed that the measured waveform around the first peak is in fair agreement with the calculated one. Furthermore, we found that the magnetic field peak increases with increasing charge voltage, whose dependence can be predicted from our equivalent model. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 153(1): 17–24, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20194     

Growth and poliovirus production of Vero cells on a novel microcarrier with artificial cell adhesive protein under serum-free conditions

A microcarrier is used for the three-dimensional (3D) culture of adhesion-dependent mammalian cells. We developed a novel microcarrier by binding ProNectin F, an artificial cell adhesive protein synthesized by genetically engineered Escherichia coli to a polyacrylic superabsorbent polymer. The microcarrier is characterized by containing no animal-derived components. The serum-free culture of Vero cells for vaccine production using the microcarrier increased the number of Vero cells by approximately 30% compared with the existing dextran beads coated with porcine Type I collagen, which resulted in approximately a 30% to 40% increase in the infectivity titer of the Sabin 2 strain of poliovirus. These results suggested that the developed microcarrier should be unprecedented in permitting high-yield vaccine production by means of a serum-free culture.     

Nonmechanical transverse scanning laser Doppler velocimeter using wavelength change

A transverse scanning laser Doppler velocimeter (LDV) that does not require any moving mechanism in its sensor probe is proposed, and the scanning function is demonstrated theoretically and experimentally. In the proposed scanning LDV, the measurement position is transversely scanned on the basis of a wavelength change induced by a tunable laser and a combination of a grating and a Dove prism. To demonstrate the scanning function in the transverse direction, an experiment was carried out using a setup of the sensor probe consisting of bulk optical components. The experimental results indicate that a transverse scanning function was successfully obtained. The scanning range in the vertical direction is estimated to be 11.3 mm over wavelengths of 1520 to 1570 nm.     

High-speed cross-sectional imaging of valuable documents using common-path swept-source optical coherence tomography

A common-path swept-source optical coherence tomography (SS-OCT) is a promising scheme for implementing a high-speed and stable OCT system. We investigate the capability of a common-path SS-OCT system to perform the cross-sectional imaging of valuable documents translated at high speed for the check of its security feature. The influence of transport speeds, up to 2000 mm/s, on the depth resolution and the signal intensity is experimentally evaluated using a SS-OCT system equipped with a swept source at a center wavelength of 1335 nm and with a sweep repetition rate of 50 kHz. The degradation of the measured signal is in good agreement with theory.