Distributed-index planar microlens array prepared from deep electromigration

Monolithic fabrication of a new distributed index planar microlens array by means of a deep electromigration technique in a glass substrate is reported. The array consists of distributed index lenses of 1.2 mm in diameter with 6.8 mm focal length. The focused spot is as small as 16 ?m for ?=0.63 ?m. The coupling efficiency of 60% to a multimode VAD fibre has been obtained.     

Optoelectronic integrated four-channel transmitter arrayincorporating AlGaAs/GaAs quantum-well lasers

A four-channel optoelectronic integrated transmitter array which is fabricated on a single GaAs substrate and operates at 834 nm is described. Each of the circuits incorporates a laser, a photodiode for laser power monitoring, and a laser driver circuit consisting of three GaAs field-effect transistors and a resistor. Laser threshold current of 15-21 mA, transmitter conversion efficiency of approximately 6 mW/V and high-speed operation at a bit rate of more than 1.5-Gb/s NRZ with allowable crosstalk have been demonstrated. A preliminary aging test of the lasers indicated that their stability is comparable to that of discrete devices. The results have demonstrated the feasibility of applying the transmitter array to optical components that process multichannel optical signals at high speed     

A co-channel interference cancellation technique using orthogonalconvolutional codes on multipath Rayleigh fading channel

This paper proposes and evaluates a new co-channel interference cancellation technique that utilizes orthogonal convolutional codes on a multipath Raleigh fading channel. In a spread spectrum multiple access environment co-channel interference (CCI) limits the performance of the communication link. To remove this interference, several CCI cancellation techniques have been proposed, including a technique that does not require the receiver to have knowledge of the cross-correlation between user sequences. This method leaves residual interference after the cancellation caused by errors in the initial decisions. To reduce the residual interference and improve the initial decisions, the proposed scheme utilizes the error-correcting capability of orthogonal convolutional codes. This paper evaluates the performance of this scheme. Our results show that the proposed CCI canceller offers an improvement in capacity of a factor of 1.5~3 as compared with a conventional canceller on a multipath Rayleigh fading channel. The proposed canceller works in the presence of residual interference due to imperfect cancellation. The proposed canceller also has a capacity improvement with the use of soft handoff in a multicell configuration     

Purification and properties of alpha-amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase (ACMSD), key enzyme of niacin synthesis from tryptophan, from hog kidney

alpha-Amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase (ACMSD) (EC 4.1.1.45) was purified to a homogeneous state from hog kidney cytosol by ammonium sulfate fractionation, Butyl-Toyopearl 650, hydroxyapatite, DEAE-Sephadex, Toyopearl HW55, Superdex 200 and TSK-gel G3000SW chromatographies. The molecular weight of the enzyme was estimated to be 58,000 by TSK-gel G3000SW gel filtration. The optimum pH (constant concentration) was 7.5. The Km for alpha-amino-beta-carboxymuconate-epsilon-semialdehyde was 1.61 x 10(-5) M. The activity of purified enzyme was inhibited by some chemical modifying reagents such as monoiodoacetic acid and p-(chloromercuri) benzoic acid. A sulfhydryl group was deduced to exist in the active site of the enzyme.     

Antioxidant activity of ferulic acid beta-glucuronide in the LDL oxidation system

Antioxidant activity of ferulic acid beta-glucuronide, which is prepared from the plasma of feruloyl arabinose fed rats, in the CuSO4- induced LDL autoxidation system was studied. It has been found that absorbed ferulic acid occurred as the beta-glucuronide and that the antioxidant activity of ferulic acid beta-glucuronide, which has not only the hydrophobic ferulic acid moiety but also a hydrophilic sugar moiety, is stronger than ferulic acid in the LDL oxidation system.     

High-speed monolithic coherent optical receiver integrated on InP substrate

A monolithic coherent receiver have a directional waveguide coupler and a balanced pair of lateral pin photodiodes was fabricated. The lateral pin photodiode has an improved structure, exhibiting a 3 dB bandwidth of 2 GHz. Heterodyne detection with this monolithic receiver was demonstrated at 1.8 GHz and 2.3 GHz.<>     

A Software Defined Radio Platform with Direct Conversion: SOPRANO

In this paper, a new software defined radio platform with direct conversionisintroduced.The platform is named SOPRANO, which stands for Software Programmableand Hardware Reconfigurable Architecture for Network.Main features of SOPRANO include a high-level design methodologyfor digital circuits, direct conversion based on six-port technology, andnovel digital signal processingalgorithms for multi-band and multi-mode operation.The first prototype of the SOPRANO platform has been built and was ableto receive M-ary PSK (Phase Shift Keying)and QAM (Quadrature Amplitude Modulation) signals,with two different carrier frequencies at 2.45 GHz and 5.25 GHz,by changing signal-processing software.     

Assessment of the activities of catalysts for the hydrocracking of coal by means of hydrogen evolution

A close relation has been found between hydrogen evolution from coal-catalyst and pitch-catalyst systems and catalytic activities of liquefaction reactions. A MoO₃?TiO₂ catalyst has the highest activity and the order of activity of the catalysts for hydrogen evolution is: MoO₃?TiO₃> MoO₃?SiO₂>10% $\text{Fe}{}_2\text{O}{}_3\text{TiO}{}_2\text{?AI}{}_2\text{O}{}_3\text{>}\text{coal alone}$. The same trend was observed for benzene-soluble materials for the hydrocracking of Akabira Coal.     

Atomic structure of nanoscale quasicrystal-forming Zr–noble metal binary metallic glasses

We report the results of the local structural evaluation and mechanism of QC formation in the Zr₇₀Pd₃₀ and Zr₈₀Pt₂₀ glassy alloys. Voronoi analysis indicates the difference of local environment between two alloys. The perfect icosahedron frequently exists around Zr atom and major polyhedra have prism-like structure around Pd in Zr₇₀Pd₃₀. In contrast, icosahedral-like distorted polyhedra formation is favorable around Pt as well as Zr in Zr₈₀Pt₂₀. It is therefore, concluded that the quasicrystallization originates from the medium-range order based on the Zr-centered perfect icosahedron and the Pd-centered prism-like ones remain during the QC phase formation in Zr₇₀Pd₃₀. Icosahedral-like local structure around Zr and Pt might contribute together to the nucleation of QC phase in Zr₈₀Pt₂₀. This feature with a different mechanism of QC formation in the two alloys may correlate to the difference of solute concentration and the structure of stable crystalline phase after the decomposition of QC phase.